1 files changed, 0 insertions, 1 deletions
diff --git a/internal/complex.h b/internal/complex.h
index 9eae804ddb..42151652b7 100644
--- a/internal/complex.h
+++ b/internal/complex.h
@@ -1,7 +1,6 @@
 #ifndef INTERNAL_COMPLEX_H                               /*-*-C-*-vi:se ft=c:*/
 #define INTERNAL_COMPLEX_H
 /**
- * @file
  * @author     Ruby developers <ruby-core@ruby-lang.org>
  * @copyright  This  file  is   a  part  of  the   programming  language  Ruby.
  *             Permission  is hereby  granted,  to  either redistribute  and/or
diff --git a/lib/English.gemspec b/lib/English.gemspec
new file mode 100644
index 0000000000..9c09555ca1
--- /dev/null
+++ b/lib/English.gemspec
@@ -0,0 +1,27 @@
+Gem::Specification.new do |spec|
+  spec.name          = "english"
+  spec.version       = "0.8.1"
+  spec.authors       = ["Yukihiro Matsumoto"]
+  spec.email         = ["matz@ruby-lang.org"]
+
+  spec.summary       = %q{Require 'English.rb' to reference global variables with less cryptic names.}
+  spec.description   = %q{Require 'English.rb' to reference global variables with less cryptic names.}
+  spec.homepage      = "https://github.com/ruby/English"
+  spec.required_ruby_version = Gem::Requirement.new(">= 2.3.0")
+  spec.licenses       = ["Ruby", "BSD-2-Clause"]
+
+  spec.metadata["homepage_uri"] = spec.homepage
+  spec.metadata["source_code_uri"] = spec.homepage
+
+  # Specify which files should be added to the gem when it is released.
+  # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
+  excludes = %W[
+    :^/test :^/spec :^/feature :^/bin
+    :^/Rakefile :^/Gemfile\* :^/.git*
+    :^/#{File.basename(__FILE__)}
+  ]
+  spec.files = IO.popen(%W[git ls-files -z --] + excludes, err: IO::NULL) do |f|
+    f.readlines("\x0", chomp: true)
+  end
+  spec.require_paths = ["lib"]
+end
diff --git a/lib/English.rb b/lib/English.rb
index 4fd53c5ec6..bf7896dcd6 100644
--- a/lib/English.rb
+++ b/lib/English.rb
@@ -1,113 +1,127 @@
+# frozen_string_literal: true
 #  Include the English library file in a Ruby script, and you can
-#  reference the global variables such as \VAR{\$\_} using less
-#  cryptic names, listed in the following table.% \vref{tab:english}.
+#  reference the global variables such as <code>$_</code> using less
+#  cryptic names, listed below.
 #
 #  Without 'English':
 #
 #      $\ = ' -- '
 #      "waterbuffalo" =~ /buff/
-#      print $", $', $$, "\n"
+#      print $', $$, "\n"
 #
-#  With English:
+#  With 'English':
 #
 #      require "English"
 #
 #      $OUTPUT_FIELD_SEPARATOR = ' -- '
 #      "waterbuffalo" =~ /buff/
-#      print $LOADED_FEATURES, $POSTMATCH, $PID, "\n"
-
+#      print $POSTMATCH, $PID, "\n"
+#
+#  Below is a full list of descriptive aliases and their associated global
+#  variable:
+#
+#  <tt>$ERROR_INFO</tt>::              <tt>$!</tt>
+#  <tt>$ERROR_POSITION</tt>::          <tt>$@</tt>
+#  <tt>$FS</tt>::                      <tt>$;</tt>
+#  <tt>$FIELD_SEPARATOR</tt>::         <tt>$;</tt>
+#  <tt>$OFS</tt>::                     <tt>$,</tt>
+#  <tt>$OUTPUT_FIELD_SEPARATOR</tt>::  <tt>$,</tt>
+#  <tt>$RS</tt>::                      <tt>$/</tt>
+#  <tt>$INPUT_RECORD_SEPARATOR</tt>::  <tt>$/</tt>
+#  <tt>$ORS</tt>::                     <tt>$\</tt>
+#  <tt>$OUTPUT_RECORD_SEPARATOR</tt>:: <tt>$\</tt>
+#  <tt>$NR</tt>::                      <tt>$.</tt>
+#  <tt>$INPUT_LINE_NUMBER</tt>::       <tt>$.</tt>
+#  <tt>$LAST_READ_LINE</tt>::          <tt>$_</tt>
+#  <tt>$DEFAULT_OUTPUT</tt>::          <tt>$></tt>
+#  <tt>$DEFAULT_INPUT</tt>::           <tt>$<</tt>
+#  <tt>$PID</tt>::                     <tt>$$</tt>
+#  <tt>$PROCESS_ID</tt>::              <tt>$$</tt>
+#  <tt>$CHILD_STATUS</tt>::            <tt>$?</tt>
+#  <tt>$LAST_MATCH_INFO</tt>::         <tt>$~</tt>
+#  <tt>$ARGV</tt>::                    <tt>$*</tt>
+#  <tt>$MATCH</tt>::                   <tt>$&</tt>
+#  <tt>$PREMATCH</tt>::                <tt>$`</tt>
+#  <tt>$POSTMATCH</tt>::               <tt>$'</tt>
+#  <tt>$LAST_PAREN_MATCH</tt>::        <tt>$+</tt>
+#
+module English end if false
 
 # The exception object passed to +raise+.
 alias $ERROR_INFO              $!
 
 # The stack backtrace generated by the last
-# exception. <tt>See Kernel.caller</tt> for details. Thread local.
+# exception. See Kernel#caller for details. Thread local.
 alias $ERROR_POSITION          $@
 
-# The default separator pattern used by <tt>String.split</tt>.  May be
-# set from the command line using the <tt>-F</tt> flag.
+# The default separator pattern used by String#split.  May be set from
+# the command line using the <code>-F</code> flag.
 alias $FS                      $;
-
-# The default separator pattern used by <tt>String.split</tt>.  May be
-# set from the command line using the <tt>-F</tt> flag.
 alias $FIELD_SEPARATOR         $;
 
 # The separator string output between the parameters to methods such
-# as <tt>Kernel.print</tt> and <tt>Array.join</tt>. Defaults to +nil+,
-# which adds no text.
-alias $OFS                     $,
+# as Kernel#print and Array#join. Defaults to +nil+, which adds no
+# text.
 
 # The separator string output between the parameters to methods such
-# as <tt>Kernel.print</tt> and <tt>Array.join</tt>. Defaults to +nil+,
-# which adds no text.
+# as Kernel#print and Array#join. Defaults to +nil+, which adds no
+# text.
+alias $OFS                     $,
 alias $OUTPUT_FIELD_SEPARATOR  $,
 
 # The input record separator (newline by default). This is the value
-# that routines such as <tt>Kernel.gets</tt> use to determine record
+# that routines such as Kernel#gets use to determine record
 # boundaries. If set to +nil+, +gets+ will read the entire file.
 alias $RS                      $/
-
-# The input record separator (newline by default). This is the value
-# that routines such as <tt>Kernel.gets</tt> use to determine record
-# boundaries. If set to +nil+, +gets+ will read the entire file.
 alias $INPUT_RECORD_SEPARATOR  $/
 
 # The string appended to the output of every call to methods such as
-# <tt>Kernel.print</tt> and <tt>IO.write</tt>. The default value is
-# +nil+.
+# Kernel#print and IO#write. The default value is +nil+.
 alias $ORS                     $\
-
-# The string appended to the output of every call to methods such as
-# <tt>Kernel.print</tt> and <tt>IO.write</tt>. The default value is
-# +nil+.
 alias $OUTPUT_RECORD_SEPARATOR $\
 
 # The number of the last line read from the current input file.
-alias $INPUT_LINE_NUMBER       $.
-
-# The number of the last line read from the current input file.
 alias $NR                      $.
+alias $INPUT_LINE_NUMBER       $.
 
-# The last line read by <tt>Kernel.gets</tt> or
-# <tt>Kernel.readline</tt>. Many string-related functions in the
-# +Kernel+ module operate on <tt>$_</tt> by default. The variable is
+# The last line read by Kernel#gets or
+# Kernel#readline. Many string-related functions in the
+# Kernel module operate on <code>$_</code> by default. The variable is
 # local to the current scope. Thread local.
 alias $LAST_READ_LINE          $_
 
-# The destination of output for <tt>Kernel.print</tt>
-# and <tt>Kernel.printf</tt>. The default value is
-# <tt>$stdout</tt>.
+# The destination of output for Kernel#print
+# and Kernel#printf. The default value is
+# <code>$stdout</code>.
 alias $DEFAULT_OUTPUT          $>
 
 # An object that provides access to the concatenation
 # of the contents of all the files
-# given as command-line arguments, or <tt>$stdin</tt>
+# given as command-line arguments, or <code>$stdin</code>
 # (in the case where there are no
-# arguments). <tt>$<</tt> supports methods similar to a
-# +File+ object:
+# arguments). <code>$<</code> supports methods similar to a
+# File object:
 # +inmode+, +close+,
-# <tt>closed?</tt>, +each+,
-# <tt>each_byte</tt>, <tt>each_line</tt>,
-# +eof+, <tt>eof?</tt>, +file+,
+# <code>closed?</code>, +each+,
+# <code>each_byte</code>, <code>each_line</code>,
+# +eof+, <code>eof?</code>, +file+,
 # +filename+, +fileno+,
 # +getc+, +gets+, +lineno+,
-# <tt>lineno=</tt>, +path+,
-# +pos+, <tt>pos=</tt>,
+# <code>lineno=</code>, +path+,
+# +pos+, <code>pos=</code>,
 # +read+, +readchar+,
 # +readline+, +readlines+,
 # +rewind+, +seek+, +skip+,
-# +tell+, <tt>to_a</tt>, <tt>to_i</tt>,
-# <tt>to_io</tt>, <tt>to_s</tt>, along with the
-# methods in +Enumerable+. The method +file+
-# returns a +File+ object for the file currently
-# being read. This may change as <tt>$<</tt> reads
+# +tell+, <code>to_a</code>, <code>to_i</code>,
+# <code>to_io</code>, <code>to_s</code>, along with the
+# methods in Enumerable. The method +file+
+# returns a File object for the file currently
+# being read. This may change as <code>$<</code> reads
 # through the files on the command line. Read only.
 alias $DEFAULT_INPUT           $<
 
 # The process number of the program being executed. Read only.
 alias $PID                     $$
-
-# The process number of the program being executed. Read only.
 alias $PROCESS_ID              $$
 
 # The exit status of the last child process to terminate. Read
@@ -115,18 +129,13 @@ alias $PROCESS_ID              $$
 alias $CHILD_STATUS            $?
 
 # A +MatchData+ object that encapsulates the results of a successful
-# pattern match. The variables <tt>$&</tt>, <tt>$`</tt>, <tt>$'</tt>,
-# and <tt>$1</tt> to <tt>$9</tt> are all derived from
-# <tt>$~</tt>. Assigning to <tt>$~</tt> changes the values of these
+# pattern match. The variables <code>$&</code>, <code>$`</code>, <code>$'</code>,
+# and <code>$1</code> to <code>$9</code> are all derived from
+# <code>$~</code>. Assigning to <code>$~</code> changes the values of these
 # derived variables.  This variable is local to the current
-# scope. Thread local.
+# scope.
 alias $LAST_MATCH_INFO         $~
 
-# If set to any value apart from +nil+ or +false+, all pattern matches
-# will be case insensitive, string comparisons will ignore case, and
-# string hash values will be case insensitive. Deprecated
-alias $IGNORECASE              $=
-
 # An array of strings containing the command-line
 # options from the invocation of the program. Options
 # used by the Ruby interpreter will have been
@@ -135,21 +144,21 @@ alias $ARGV                    $*
 
 # The string matched by the last successful pattern
 # match. This variable is local to the current
-# scope. Read only. Thread local.
+# scope. Read only.
 alias $MATCH                   $&
 
 # The string preceding the match in the last
 # successful pattern match. This variable is local to
-# the current scope. Read only. Thread local.
+# the current scope. Read only.
 alias $PREMATCH                $`
 
 # The string following the match in the last
 # successful pattern match. This variable is local to
-# the current scope. Read only. Thread local.
+# the current scope. Read only.
 alias $POSTMATCH               $'
 
 # The contents of the highest-numbered group matched in the last
-# successful pattern match. Thus, in <tt>"cat" =~ /(c|a)(t|z)/</tt>,
-# <tt>$+</tt> will be set to "t".  This variable is local to the
-# current scope. Read only. Thread local.
+# successful pattern match. Thus, in <code>"cat" =~ /(c|a)(t|z)/</code>,
+# <code>$+</code> will be set to "t".  This variable is local to the
+# current scope. Read only.
 alias $LAST_PAREN_MATCH        $+
diff --git a/lib/README b/lib/README
deleted file mode 100644
index cfe7145307..0000000000
--- a/lib/README
+++ /dev/null
@@ -1,91 +0,0 @@
-English.rb	lets Perl'ish global variables have English names
-README		this file
-abbrev.rb	abbreviation calculator
-base64.rb	Base64 de- and encoder
-benchmark.rb	a benchmark utility
-cgi.rb		CGI support library
-cgi/session.rb	CGI session class
-cmath.rb	math support for complex numbers
-complex.rb	includes cmath and set complex arithemtic as default (obsolete)
-csv.rb		CSV parser/generator
-debug.rb	ruby debugger
-delegate.rb	delegates messages to other object
-drb.rb		distributed Ruby
-e2mmap.rb	exception utilities
-erb.rb		tiny eRuby library
-fileutils.rb	file utilities
-find.rb		traverses directory tree
-forwardable.rb	explicit delegation library
-gauntlet_rubygems.rb 	Gem package validator
-getoptlong.rb	GNU getoptlong compatible
-gserver.rb	general TCP server
-ipaddr.rb	defines the IPAddr class
-irb.rb		interactive ruby
-logger.rb	simple logging utility
-mathn.rb	extended math operation (obsolete)
-matrix.rb	matrix calculation library
-minitest/unit	minimal drop-in replacement for test-unit
-mkmf.rb		Makefile maker
-monitor.rb	exclusive region monitor for thread
-mutex_m.rb	mutex mixin
-net/ftp.rb	ftp access
-net/http.rb	HTTP access
-net/https.rb	HTTPS access
-net/imap.rb	IMAP4 access
-net/pop.rb	POP3 access
-net/protocol.rb	abstract class for net library (DO NOT USE)
-net/smtp.rb	SMTP access
-net/telnet.rb	telnet library
-observer.rb	observer desing pattern library (provides Observable)
-open-uri.rb	easy-to-use network interface using URI and Net
-open3.rb	opens subprocess connection stdin/stdout/stderr
-optparse.rb	command line option analysis
-ostruct.rb	python style object
-pathname.rb	Object-Oriented Pathname Class
-pp.rb		pretty print objects
-prettyprint.rb	pretty printing algorithm
-prime.rb        prime numbers and factorization
-profile.rb	runs ruby profiler
-profiler.rb	ruby profiler module
-pstore.rb	persistent object strage using marshal
-racc/parser.rb	racc (Ruby yACC) runtime
-rake.rb		Ruby Make
-rational.rb	rational number support (obsolete)
-rdoc		source-code documentation tool
-resolv-replace.rb	replace Socket DNS by resolve.rb
-resolv.rb	DNS resolver in Ruby
-rexml		an XML parser for Ruby, in Ruby
-rinda/rinda.rb	Linda distributed computing paradigm for drb
-rinda/ring.rb	RingServer for tuplespace
-rinda/tuplespace.rb	tuplespace for drb
-rss.rb		RSS parser/generator
-rubygems	Ruby package management system
-scanf.rb	scanf for Ruby
-securerandom.rb	Secure random number generator interface
-set.rb		defines the Set class
-shell.rb	runs commands and does pipeline operations like shell
-shellwords.rb	split into words like shell
-singleton.rb	singleton design pattern library
-sync.rb		2 phase lock
-tempfile.rb	temporary file with automatic removal
-test/unit	Ruby Unit Testing Framework
-thread.rb	thread support
-thwait.rb	thread syncronization class
-time.rb		RFC2822, RFC2616, ISO8601 style time formatting/parsing
-timeout.rb	provides timeout
-tmpdir.rb	retrieve temporary directory path
-tracer.rb	execution tracer
-tsort.rb	topological sorting
-ubygems.rb	command line shortcut for RubyGems
-un.rb		Utilities to replace common UNIX commands in Makefiles etc
-uri.rb		URI support
-uri/ftp.rb	ftp scheme support
-uri/http.rb	http scheme support
-uri/https.rb	https scheme support
-uri/ldap.rb	ldap scheme support
-uri/ldaps.rb	ldaps scheme support
-uri/mailto.rb	mailto scheme support
-weakref.rb	weak reference class
-webrick.rb	WEB server toolkit
-xmlrpc		XML-RPC implementation
-yaml.rb		YAML implementation
diff --git a/lib/abbrev.rb b/lib/abbrev.rb
deleted file mode 100644
index aa7e33a65d..0000000000
--- a/lib/abbrev.rb
+++ /dev/null
@@ -1,102 +0,0 @@
-#!/usr/bin/env ruby
-#--
-# Copyright (c) 2001,2003 Akinori MUSHA <knu@iDaemons.org>
-#
-# All rights reserved.  You can redistribute and/or modify it under
-# the same terms as Ruby.
-#
-# $Idaemons: /home/cvs/rb/abbrev.rb,v 1.2 2001/05/30 09:37:45 knu Exp $
-# $RoughId: abbrev.rb,v 1.4 2003/10/14 19:45:42 knu Exp $
-# $Id$
-#++
-
-# Calculate the set of unique abbreviations for a given set of strings.
-#
-#   require 'abbrev'
-#   require 'pp'
-#
-#   pp Abbrev::abbrev(['ruby', 'rules']).sort
-#
-# <i>Generates:</i>
-#
-#   [["rub", "ruby"],
-#    ["ruby", "ruby"],
-#    ["rul", "rules"],
-#    ["rule", "rules"],
-#    ["rules", "rules"]]
-#
-# Also adds an +abbrev+ method to class +Array+.
-
-module Abbrev
-
-  # Given a set of strings, calculate the set of unambiguous
-  # abbreviations for those strings, and return a hash where the keys
-  # are all the possible abbreviations and the values are the full
-  # strings. Thus, given input of "car" and "cone", the keys pointing
-  # to "car" would be "ca" and "car", while those pointing to "cone"
-  # would be "co", "con", and "cone".
-  #
-  # The optional +pattern+ parameter is a pattern or a string. Only
-  # those input strings matching the pattern, or begging the string,
-  # are considered for inclusion in the output hash
-
-  def abbrev(words, pattern = nil)
-    table = {}
-    seen = Hash.new(0)
-
-    if pattern.is_a?(String)
-      pattern = /^#{Regexp.quote(pattern)}/  # regard as a prefix
-    end
-
-    words.each do |word|
-      next if (abbrev = word).empty?
-      while (len = abbrev.rindex(/[\w\W]\z/)) > 0
-        abbrev = word[0,len]
-
-        next if pattern && pattern !~ abbrev
-
-        case seen[abbrev] += 1
-        when 1
-          table[abbrev] = word
-        when 2
-          table.delete(abbrev)
-        else
-          break
-        end
-      end
-    end
-
-    words.each do |word|
-      next if pattern && pattern !~ word
-
-      table[word] = word
-    end
-
-    table
-  end
-
-  module_function :abbrev
-end
-
-class Array
-  # Calculates the set of unambiguous abbreviations for the strings in
-  # +self+. If passed a pattern or a string, only the strings matching
-  # the pattern or starting with the string are considered.
-  #
-  #   %w{ car cone }.abbrev   #=> { "ca" => "car", "car" => "car",
-  #                                 "co" => "cone", "con" => cone",
-  #                                 "cone" => "cone" }
-  def abbrev(pattern = nil)
-    Abbrev::abbrev(self, pattern)
-  end
-end
-
-if $0 == __FILE__
-  while line = gets
-    hash = line.split.abbrev
-
-    hash.sort.each do |k, v|
-      puts "#{k} => #{v}"
-    end
-  end
-end
diff --git a/lib/base64.rb b/lib/base64.rb
deleted file mode 100644
index a240b730b4..0000000000
--- a/lib/base64.rb
+++ /dev/null
@@ -1,91 +0,0 @@
-#
-# = base64.rb: methods for base64-encoding and -decoding strings
-#
-
-# The Base64 module provides for the encoding (#encode64, #strict_encode64,
-# #urlsafe_encode64) and decoding (#decode64, #strict_decode64,
-# #urlsafe_decode64) of binary data using a Base64 representation.
-#
-# == Example
-#
-# A simple encoding and decoding.
-#
-#     require "base64"
-#
-#     enc   = Base64.encode64('Send reinforcements')
-#                         # -> "U2VuZCByZWluZm9yY2VtZW50cw==\n"
-#     plain = Base64.decode64(enc)
-#                         # -> "Send reinforcements"
-#
-# The purpose of using base64 to encode data is that it translates any
-# binary data into purely printable characters.
-
-module Base64
-  module_function
-
-  # Returns the Base64-encoded version of +bin+.
-  # This method complies with RFC 2045.
-  # Line feeds are added to every 60 encoded charactors.
-  #
-  #    require 'base64'
-  #    Base64.encode64("Now is the time for all good coders\nto learn Ruby")
-  #
-  # <i>Generates:</i>
-  #
-  #    Tm93IGlzIHRoZSB0aW1lIGZvciBhbGwgZ29vZCBjb2RlcnMKdG8gbGVhcm4g
-  #    UnVieQ==
-  def encode64(bin)
-    [bin].pack("m")
-  end
-
-  # Returns the Base64-decoded version of +str+.
-  # This method complies with RFC 2045.
-  # Characters outside the base alphabet are ignored.
-  #
-  #   require 'base64'
-  #   str = 'VGhpcyBpcyBsaW5lIG9uZQpUaGlzIG' +
-  #         'lzIGxpbmUgdHdvClRoaXMgaXMgbGlu' +
-  #         'ZSB0aHJlZQpBbmQgc28gb24uLi4K'
-  #   puts Base64.decode64(str)
-  #
-  # <i>Generates:</i>
-  #
-  #    This is line one
-  #    This is line two
-  #    This is line three
-  #    And so on...
-  def decode64(str)
-    str.unpack("m").first
-  end
-
-  # Returns the Base64-encoded version of +bin+.
-  # This method complies with RFC 4648.
-  # No line feeds are added.
-  def strict_encode64(bin)
-    [bin].pack("m0")
-  end
-
-  # Returns the Base64-decoded version of +str+.
-  # This method complies with RFC 4648.
-  # ArgumentError is raised if +str+ is incorrectly padded or contains
-  # non-alphabet characters.  Note that CR or LF are also rejected.
-  def strict_decode64(str)
-    str.unpack("m0").first
-  end
-
-  # Returns the Base64-encoded version of +bin+.
-  # This method complies with ``Base 64 Encoding with URL and Filename Safe
-  # Alphabet'' in RFC 4648.
-  # The alphabet uses '-' instead of '+' and '_' instead of '/'.
-  def urlsafe_encode64(bin)
-    strict_encode64(bin).tr("+/", "-_")
-  end
-
-  # Returns the Base64-decoded version of +str+.
-  # This method complies with ``Base 64 Encoding with URL and Filename Safe
-  # Alphabet'' in RFC 4648.
-  # The alphabet uses '-' instead of '+' and '_' instead of '/'.
-  def urlsafe_decode64(str)
-    strict_decode64(str.tr("-_", "+/"))
-  end
-end
diff --git a/lib/benchmark.rb b/lib/benchmark.rb
deleted file mode 100644
index 6a00da1359..0000000000
--- a/lib/benchmark.rb
+++ /dev/null
@@ -1,569 +0,0 @@
-#--
-# benchmark.rb - a performance benchmarking library
-#
-# $Id$
-#
-# Created by Gotoken (gotoken@notwork.org).
-#
-# Documentation by Gotoken (original RD), Lyle Johnson (RDoc conversion), and
-# Gavin Sinclair (editing).
-#++
-#
-# == Overview
-#
-# The Benchmark module provides methods for benchmarking Ruby code, giving
-# detailed reports on the time taken for each task.
-#
-
-# The Benchmark module provides methods to measure and report the time
-# used to execute Ruby code.
-#
-# * Measure the time to construct the string given by the expression
-#   <tt>"a"*1_000_000</tt>:
-#
-#       require 'benchmark'
-#
-#       puts Benchmark.measure { "a"*1_000_000 }
-#
-#   On my machine (FreeBSD 3.2 on P5, 100MHz) this generates:
-#
-#       1.166667   0.050000   1.216667 (  0.571355)
-#
-#   This report shows the user CPU time, system CPU time, the sum of
-#   the user and system CPU times, and the elapsed real time. The unit
-#   of time is seconds.
-#
-# * Do some experiments sequentially using the #bm method:
-#
-#       require 'benchmark'
-#
-#       n = 50000
-#       Benchmark.bm do |x|
-#         x.report { for i in 1..n; a = "1"; end }
-#         x.report { n.times do   ; a = "1"; end }
-#         x.report { 1.upto(n) do ; a = "1"; end }
-#       end
-#
-#   The result:
-#
-#              user     system      total        real
-#          1.033333   0.016667   1.016667 (  0.492106)
-#          1.483333   0.000000   1.483333 (  0.694605)
-#          1.516667   0.000000   1.516667 (  0.711077)
-#
-# * Continuing the previous example, put a label in each report:
-#
-#       require 'benchmark'
-#
-#       n = 50000
-#       Benchmark.bm(7) do |x|
-#         x.report("for:")   { for i in 1..n; a = "1"; end }
-#         x.report("times:") { n.times do   ; a = "1"; end }
-#         x.report("upto:")  { 1.upto(n) do ; a = "1"; end }
-#       end
-#
-# The result:
-#
-#                     user     system      total        real
-#        for:     1.050000   0.000000   1.050000 (  0.503462)
-#        times:   1.533333   0.016667   1.550000 (  0.735473)
-#        upto:    1.500000   0.016667   1.516667 (  0.711239)
-#
-#
-# * The times for some benchmarks depend on the order in which items
-#   are run.  These differences are due to the cost of memory
-#   allocation and garbage collection. To avoid these discrepancies,
-#   the #bmbm method is provided.  For example, to compare ways to
-#   sort an array of floats:
-#
-#       require 'benchmark'
-#
-#       array = (1..1000000).map { rand }
-#
-#       Benchmark.bmbm do |x|
-#         x.report("sort!") { array.dup.sort! }
-#         x.report("sort")  { array.dup.sort  }
-#       end
-#
-#   The result:
-#
-#        Rehearsal -----------------------------------------
-#        sort!  11.928000   0.010000  11.938000 ( 12.756000)
-#        sort   13.048000   0.020000  13.068000 ( 13.857000)
-#        ------------------------------- total: 25.006000sec
-#
-#                    user     system      total        real
-#        sort!  12.959000   0.010000  12.969000 ( 13.793000)
-#        sort   12.007000   0.000000  12.007000 ( 12.791000)
-#
-#
-# * Report statistics of sequential experiments with unique labels,
-#   using the #benchmark method:
-#
-#       require 'benchmark'
-#       include Benchmark         # we need the CAPTION and FORMAT constants
-#
-#       n = 50000
-#       Benchmark.benchmark(CAPTION, 7, FORMAT, ">total:", ">avg:") do |x|
-#         tf = x.report("for:")   { for i in 1..n; a = "1"; end }
-#         tt = x.report("times:") { n.times do   ; a = "1"; end }
-#         tu = x.report("upto:")  { 1.upto(n) do ; a = "1"; end }
-#         [tf+tt+tu, (tf+tt+tu)/3]
-#       end
-#
-#   The result:
-#
-#                     user     system      total        real
-#        for:     1.016667   0.016667   1.033333 (  0.485749)
-#        times:   1.450000   0.016667   1.466667 (  0.681367)
-#        upto:    1.533333   0.000000   1.533333 (  0.722166)
-#        >total:  4.000000   0.033333   4.033333 (  1.889282)
-#        >avg:    1.333333   0.011111   1.344444 (  0.629761)
-
-module Benchmark
-
-  BENCHMARK_VERSION = "2002-04-25" #:nodoc"
-
-  # Invokes the block with a <tt>Benchmark::Report</tt> object, which
-  # may be used to collect and report on the results of individual
-  # benchmark tests. Reserves <i>label_width</i> leading spaces for
-  # labels on each line. Prints _caption_ at the top of the
-  # report, and uses _format_ to format each line.
-  # Returns an array of Benchmark::Tms objects.
-  #
-  # If the block returns an array of
-  # <tt>Benchmark::Tms</tt> objects, these will be used to format
-  # additional lines of output. If _label_ parameters are
-  # given, these are used to label these extra lines.
-  #
-  # _Note_: Other methods provide a simpler interface to this one, and are
-  # suitable for nearly all benchmarking requirements.  See the examples in
-  # Benchmark, and the #bm and #bmbm methods.
-  #
-  # Example:
-  #
-  #     require 'benchmark'
-  #     include Benchmark          # we need the CAPTION and FORMAT constants
-  #
-  #     n = 50000
-  #     Benchmark.benchmark(CAPTION, 7, FORMAT, ">total:", ">avg:") do |x|
-  #       tf = x.report("for:")   { for i in 1..n; a = "1"; end }
-  #       tt = x.report("times:") { n.times do   ; a = "1"; end }
-  #       tu = x.report("upto:")  { 1.upto(n) do ; a = "1"; end }
-  #       [tf+tt+tu, (tf+tt+tu)/3]
-  #     end
-  #
-  # <i>Generates:</i>
-  #
-  #                     user     system      total        real
-  #        for:     1.016667   0.016667   1.033333 (  0.485749)
-  #        times:   1.450000   0.016667   1.466667 (  0.681367)
-  #        upto:    1.533333   0.000000   1.533333 (  0.722166)
-  #        >total:  4.000000   0.033333   4.033333 (  1.889282)
-  #        >avg:    1.333333   0.011111   1.344444 (  0.629761)
-  #
-
-  def benchmark(caption = "", label_width = nil, format = nil, *labels) # :yield: report
-    sync = STDOUT.sync
-    STDOUT.sync = true
-    label_width ||= 0
-    label_width += 1
-    format ||= FORMAT
-    print ' '*label_width + caption
-    report = Report.new(label_width, format)
-    results = yield(report)
-    Array === results and results.grep(Tms).each {|t|
-      print((labels.shift || t.label || "").ljust(label_width), t.format(format))
-    }
-    report.list
-  ensure
-    STDOUT.sync = sync unless sync.nil?
-  end
-
-
-  # A simple interface to the #benchmark method, #bm is generates sequential reports
-  # with labels.  The parameters have the same meaning as for #benchmark.
-  #
-  #     require 'benchmark'
-  #
-  #     n = 50000
-  #     Benchmark.bm(7) do |x|
-  #       x.report("for:")   { for i in 1..n; a = "1"; end }
-  #       x.report("times:") { n.times do   ; a = "1"; end }
-  #       x.report("upto:")  { 1.upto(n) do ; a = "1"; end }
-  #     end
-  #
-  # <i>Generates:</i>
-  #
-  #                     user     system      total        real
-  #        for:     1.050000   0.000000   1.050000 (  0.503462)
-  #        times:   1.533333   0.016667   1.550000 (  0.735473)
-  #        upto:    1.500000   0.016667   1.516667 (  0.711239)
-  #
-
-  def bm(label_width = 0, *labels, &blk) # :yield: report
-    benchmark(CAPTION, label_width, FORMAT, *labels, &blk)
-  end
-
-
-  # Sometimes benchmark results are skewed because code executed
-  # earlier encounters different garbage collection overheads than
-  # that run later. #bmbm attempts to minimize this effect by running
-  # the tests twice, the first time as a rehearsal in order to get the
-  # runtime environment stable, the second time for
-  # real. <tt>GC.start</tt> is executed before the start of each of
-  # the real timings; the cost of this is not included in the
-  # timings. In reality, though, there's only so much that #bmbm can
-  # do, and the results are not guaranteed to be isolated from garbage
-  # collection and other effects.
-  #
-  # Because #bmbm takes two passes through the tests, it can
-  # calculate the required label width.
-  #
-  #       require 'benchmark'
-  #
-  #       array = (1..1000000).map { rand }
-  #
-  #       Benchmark.bmbm do |x|
-  #         x.report("sort!") { array.dup.sort! }
-  #         x.report("sort")  { array.dup.sort  }
-  #       end
-  #
-  # <i>Generates:</i>
-  #
-  #        Rehearsal -----------------------------------------
-  #        sort!  11.928000   0.010000  11.938000 ( 12.756000)
-  #        sort   13.048000   0.020000  13.068000 ( 13.857000)
-  #        ------------------------------- total: 25.006000sec
-  #
-  #                    user     system      total        real
-  #        sort!  12.959000   0.010000  12.969000 ( 13.793000)
-  #        sort   12.007000   0.000000  12.007000 ( 12.791000)
-  #
-  # #bmbm yields a Benchmark::Job object and returns an array of
-  # Benchmark::Tms objects.
-  #
-  def bmbm(width = 0, &blk) # :yield: job
-    job = Job.new(width)
-    yield(job)
-    width = job.width + 1
-    sync = STDOUT.sync
-    STDOUT.sync = true
-
-    # rehearsal
-    puts 'Rehearsal '.ljust(width+CAPTION.length,'-')
-    ets = job.list.inject(Tms.new) { |sum,(label,item)|
-      print label.ljust(width)
-      res = Benchmark.measure(&item)
-      print res.format
-      sum + res
-    }.format("total: %tsec")
-    print " #{ets}\n\n".rjust(width+CAPTION.length+2,'-')
-
-    # take
-    print ' '*width + CAPTION
-    job.list.map { |label,item|
-      GC.start
-      print label.ljust(width)
-      Benchmark.measure(label, &item).tap { |res| print res }
-    }
-  ensure
-    STDOUT.sync = sync unless sync.nil?
-  end
-
-  #
-  # Returns the time used to execute the given block as a
-  # Benchmark::Tms object.
-  #
-  def measure(label = "") # :yield:
-    t0, r0 = Process.times, Time.now
-    yield
-    t1, r1 = Process.times, Time.now
-    Benchmark::Tms.new(t1.utime  - t0.utime,
-                       t1.stime  - t0.stime,
-                       t1.cutime - t0.cutime,
-                       t1.cstime - t0.cstime,
-                       r1.to_f - r0.to_f,
-                       label)
-  end
-
-  #
-  # Returns the elapsed real time used to execute the given block.
-  #
-  def realtime # :yield:
-    r0 = Time.now
-    yield
-    Time.now - r0
-  end
-
-  module_function :benchmark, :measure, :realtime, :bm, :bmbm
-
-  #
-  # A Job is a sequence of labelled blocks to be processed by the
-  # Benchmark.bmbm method.  It is of little direct interest to the user.
-  #
-  class Job # :nodoc:
-    #
-    # Returns an initialized Job instance.
-    # Usually, one doesn't call this method directly, as new
-    # Job objects are created by the #bmbm method.
-    # _width_ is a initial value for the label offset used in formatting;
-    # the #bmbm method passes its _width_ argument to this constructor.
-    #
-    def initialize(width)
-      @width = width
-      @list = []
-    end
-
-    #
-    # Registers the given label and block pair in the job list.
-    #
-    def item(label = "", &blk) # :yield:
-      raise ArgumentError, "no block" unless block_given?
-      label = label.to_s
-      w = label.length
-      @width = w if @width < w
-      @list << [label, blk]
-      self
-    end
-
-    alias report item
-
-    # An array of 2-element arrays, consisting of label and block pairs.
-    attr_reader :list
-
-    # Length of the widest label in the #list.
-    attr_reader :width
-  end
-
-  #
-  # This class is used by the Benchmark.benchmark and Benchmark.bm methods.
-  # It is of little direct interest to the user.
-  #
-  class Report # :nodoc:
-    #
-    # Returns an initialized Report instance.
-    # Usually, one doesn't call this method directly, as new
-    # Report objects are created by the #benchmark and #bm methods.
-    # _width_ and _format_ are the label offset and
-    # format string used by Tms#format.
-    #
-    def initialize(width = 0, format = nil)
-      @width, @format, @list = width, format, []
-    end
-
-    #
-    # Prints the _label_ and measured time for the block,
-    # formatted by _format_. See Tms#format for the
-    # formatting rules.
-    #
-    def item(label = "", *format, &blk) # :yield:
-      print label.to_s.ljust(@width)
-      @list << res = Benchmark.measure(label, &blk)
-      print res.format(@format, *format)
-      res
-    end
-
-    alias report item
-
-    # An array of Benchmark::Tms objects representing each item.
-    attr_reader :list
-  end
-
-
-
-  #
-  # A data object, representing the times associated with a benchmark
-  # measurement.
-  #
-  class Tms
-
-    # Default caption, see also Benchmark::CAPTION
-    CAPTION = "      user     system      total        real\n"
-
-    # Default format string, see also Benchmark::FORMAT
-    FORMAT = "%10.6u %10.6y %10.6t %10.6r\n"
-
-    # User CPU time
-    attr_reader :utime
-
-    # System CPU time
-    attr_reader :stime
-
-    # User CPU time of children
-    attr_reader :cutime
-
-    # System CPU time of children
-    attr_reader :cstime
-
-    # Elapsed real time
-    attr_reader :real
-
-    # Total time, that is _utime_ + _stime_ + _cutime_ + _cstime_
-    attr_reader :total
-
-    # Label
-    attr_reader :label
-
-    #
-    # Returns an initialized Tms object which has
-    # _utime_ as the user CPU time, _stime_ as the system CPU time,
-    # _cutime_ as the children's user CPU time, _cstime_ as the children's
-    # system CPU time, _real_ as the elapsed real time and _label_ as the label.
-    #
-    def initialize(utime = 0.0, stime = 0.0, cutime = 0.0, cstime = 0.0, real = 0.0, label = nil)
-      @utime, @stime, @cutime, @cstime, @real, @label = utime, stime, cutime, cstime, real, label.to_s
-      @total = @utime + @stime + @cutime + @cstime
-    end
-
-    #
-    # Returns a new Tms object whose times are the sum of the times for this
-    # Tms object, plus the time required to execute the code block (_blk_).
-    #
-    def add(&blk) # :yield:
-      self + Benchmark.measure(&blk)
-    end
-
-    #
-    # An in-place version of #add.
-    #
-    def add!(&blk)
-      t = Benchmark.measure(&blk)
-      @utime  = utime + t.utime
-      @stime  = stime + t.stime
-      @cutime = cutime + t.cutime
-      @cstime = cstime + t.cstime
-      @real   = real + t.real
-      self
-    end
-
-    #
-    # Returns a new Tms object obtained by memberwise summation
-    # of the individual times for this Tms object with those of the other
-    # Tms object.
-    # This method and #/() are useful for taking statistics.
-    #
-    def +(other); memberwise(:+, other) end
-
-    #
-    # Returns a new Tms object obtained by memberwise subtraction
-    # of the individual times for the other Tms object from those of this
-    # Tms object.
-    #
-    def -(other); memberwise(:-, other) end
-
-    #
-    # Returns a new Tms object obtained by memberwise multiplication
-    # of the individual times for this Tms object by _x_.
-    #
-    def *(x); memberwise(:*, x) end
-
-    #
-    # Returns a new Tms object obtained by memberwise division
-    # of the individual times for this Tms object by _x_.
-    # This method and #+() are useful for taking statistics.
-    #
-    def /(x); memberwise(:/, x) end
-
-    #
-    # Returns the contents of this Tms object as
-    # a formatted string, according to a format string
-    # like that passed to Kernel.format. In addition, #format
-    # accepts the following extensions:
-    #
-    # <tt>%u</tt>::     Replaced by the user CPU time, as reported by Tms#utime.
-    # <tt>%y</tt>::     Replaced by the system CPU time, as reported by #stime (Mnemonic: y of "s*y*stem")
-    # <tt>%U</tt>::     Replaced by the children's user CPU time, as reported by Tms#cutime
-    # <tt>%Y</tt>::     Replaced by the children's system CPU time, as reported by Tms#cstime
-    # <tt>%t</tt>::     Replaced by the total CPU time, as reported by Tms#total
-    # <tt>%r</tt>::     Replaced by the elapsed real time, as reported by Tms#real
-    # <tt>%n</tt>::     Replaced by the label string, as reported by Tms#label (Mnemonic: n of "*n*ame")
-    #
-    # If _format_ is not given, FORMAT is used as default value, detailing the
-    # user, system and real elapsed time.
-    #
-    def format(format = nil, *args)
-      str = (format || FORMAT).dup
-      str.gsub!(/(%[-+\.\d]*)n/) { "#{$1}s" % label }
-      str.gsub!(/(%[-+\.\d]*)u/) { "#{$1}f" % utime }
-      str.gsub!(/(%[-+\.\d]*)y/) { "#{$1}f" % stime }
-      str.gsub!(/(%[-+\.\d]*)U/) { "#{$1}f" % cutime }
-      str.gsub!(/(%[-+\.\d]*)Y/) { "#{$1}f" % cstime }
-      str.gsub!(/(%[-+\.\d]*)t/) { "#{$1}f" % total }
-      str.gsub!(/(%[-+\.\d]*)r/) { "(#{$1}f)" % real }
-      format ? str % args : str
-    end
-
-    #
-    # Same as #format.
-    #
-    def to_s
-      format
-    end
-
-    #
-    # Returns a new 6-element array, consisting of the
-    # label, user CPU time, system CPU time, children's
-    # user CPU time, children's system CPU time and elapsed
-    # real time.
-    #
-    def to_a
-      [@label, @utime, @stime, @cutime, @cstime, @real]
-    end
-
-    protected
-    
-    #
-    # Returns a new Tms object obtained by memberwise operation +op+
-    # of the individual times for this Tms object with those of the other
-    # Tms object.
-    #
-    # +op+ can be a mathematical operation such as <tt>+</tt>, <tt>-</tt>,
-    # <tt>*</tt>, <tt>/</tt>
-    #
-    def memberwise(op, x)
-      case x
-      when Benchmark::Tms
-        Benchmark::Tms.new(utime.__send__(op, x.utime),
-                           stime.__send__(op, x.stime),
-                           cutime.__send__(op, x.cutime),
-                           cstime.__send__(op, x.cstime),
-                           real.__send__(op, x.real)
-                           )
-      else
-        Benchmark::Tms.new(utime.__send__(op, x),
-                           stime.__send__(op, x),
-                           cutime.__send__(op, x),
-                           cstime.__send__(op, x),
-                           real.__send__(op, x)
-                           )
-      end
-    end
-  end
-
-  # The default caption string (heading above the output times).
-  CAPTION = Benchmark::Tms::CAPTION
-
-  # The default format string used to display times.  See also Benchmark::Tms#format.
-  FORMAT = Benchmark::Tms::FORMAT
-end
-
-if __FILE__ == $0
-  include Benchmark
-
-  n = ARGV[0].to_i.nonzero? || 50000
-  puts %Q([#{n} times iterations of `a = "1"'])
-  benchmark("       " + CAPTION, 7, FORMAT) do |x|
-    x.report("for:")   {for _ in 1..n; _ = "1"; end} # Benchmark.measure
-    x.report("times:") {n.times do   ; _ = "1"; end}
-    x.report("upto:")  {1.upto(n) do ; _ = "1"; end}
-  end
-
-  benchmark do
-    [
-      measure{for _ in 1..n; _ = "1"; end},  # Benchmark.measure
-      measure{n.times do   ; _ = "1"; end},
-      measure{1.upto(n) do ; _ = "1"; end}
-    ]
-  end
-end
diff --git a/lib/bundled_gems.rb b/lib/bundled_gems.rb
new file mode 100644
index 0000000000..a287c49a34
--- /dev/null
+++ b/lib/bundled_gems.rb
@@ -0,0 +1,275 @@
+# -*- frozen-string-literal: true -*-
+
+module Gem # :nodoc:
+  # TODO: the nodoc above is a workaround for RDoc's Prism parser handling stopdoc differently, we may want to use
+  # stopdoc/startdoc pair like before
+end
+
+module Gem::BUNDLED_GEMS # :nodoc:
+  SINCE = {
+    "racc" => "3.3.0",
+    "abbrev" => "3.4.0",
+    "base64" => "3.4.0",
+    "bigdecimal" => "3.4.0",
+    "csv" => "3.4.0",
+    "drb" => "3.4.0",
+    "getoptlong" => "3.4.0",
+    "mutex_m" => "3.4.0",
+    "nkf" => "3.4.0",
+    "observer" => "3.4.0",
+    "resolv-replace" => "3.4.0",
+    "rinda" => "3.4.0",
+    "syslog" => "3.4.0",
+    "ostruct" => "4.0.0",
+    "pstore" => "4.0.0",
+    "rdoc" => "4.0.0",
+    "win32ole" => "4.0.0",
+    "fiddle" => "4.0.0",
+    "logger" => "4.0.0",
+    "benchmark" => "4.0.0",
+    "irb" => "4.0.0",
+    "reline" => "4.0.0",
+    # "readline" => "4.0.0", # This is wrapper for reline. We don't warn for this.
+    "tsort" => "4.1.0",
+  }.freeze
+
+  EXACT = {
+    "kconv" => "nkf",
+  }.freeze
+
+  WARNED = {}                   # unfrozen
+
+  conf = ::RbConfig::CONFIG
+  LIBDIR = (conf["rubylibdir"] + "/").freeze
+  ARCHDIR = (conf["rubyarchdir"] + "/").freeze
+  dlext = [conf["DLEXT"], "so"].uniq
+  DLEXT = /\.#{Regexp.union(dlext)}\z/
+  LIBEXT = /\.#{Regexp.union("rb", *dlext)}\z/
+
+  def self.replace_require(specs)
+    return if [::Kernel.singleton_class, ::Kernel].any? {|klass| klass.respond_to?(:no_warning_require) }
+
+    spec_names = specs.to_a.each_with_object({}) {|spec, h| h[spec.name] = true }
+
+    [::Kernel.singleton_class, ::Kernel].each do |kernel_class|
+      kernel_class.send(:alias_method, :no_warning_require, :require)
+      kernel_class.send(:define_method, :require) do |name|
+        if message = ::Gem::BUNDLED_GEMS.warning?(name, specs: spec_names)
+          Kernel.warn message, uplevel: ::Gem::BUNDLED_GEMS.uplevel
+        end
+        kernel_class.send(:no_warning_require, name)
+      end
+      if kernel_class == ::Kernel
+        kernel_class.send(:private, :require)
+      else
+        kernel_class.send(:public, :require)
+      end
+    end
+  end
+
+  def self.uplevel
+    frame_count = 0
+    require_labels = ["replace_require", "require"]
+    uplevel = 0
+    require_found = false
+    Thread.each_caller_location do |cl|
+      frame_count += 1
+
+      if require_found
+        unless require_labels.include?(cl.base_label)
+          return uplevel
+        end
+      else
+        if require_labels.include?(cl.base_label)
+          require_found = true
+        end
+      end
+      uplevel += 1
+      # Don't show script name when bundle exec and call ruby script directly.
+      if cl.path.end_with?("bundle")
+        return
+      end
+    end
+    require_found ? 1 : (frame_count - 1).nonzero?
+  end
+
+  def self.warning?(name, specs: nil)
+    # name can be a feature name or a file path with String or Pathname
+    feature = File.path(name).sub(LIBEXT, "")
+
+    # The actual checks needed to properly identify the gem being required
+    # are costly (see [Bug #20641]), so we first do a much cheaper check
+    # to exclude the vast majority of candidates.
+    subfeature = if feature.include?("/")
+      # bootsnap expands `require "csv"` to `require "#{LIBDIR}/csv.rb"`,
+      # and `require "syslog"` to `require "#{ARCHDIR}/syslog.so"`.
+      feature.delete_prefix!(ARCHDIR)
+      feature.delete_prefix!(LIBDIR)
+      # 1. A segment for the EXACT mapping and SINCE check
+      # 2. A segment for the SINCE check for dashed names
+      # 3. A segment to check if there's a subfeature
+      segments = feature.split("/", 3)
+      name = segments.shift
+      name = EXACT[name] || name
+      if !SINCE[name]
+        name = "#{name}-#{segments.shift}"
+        return unless SINCE[name]
+      end
+      segments.any?
+    else
+      name = EXACT[feature] || feature
+      return unless SINCE[name]
+      false
+    end
+
+    if suppress_list = Thread.current[:__bundled_gems_warning_suppression]
+      return if suppress_list.include?(name) || suppress_list.include?(feature)
+    end
+
+    return if specs.include?(name)
+
+    # Don't warn if a hyphenated gem provides this feature
+    # (e.g., benchmark-ips provides benchmark/ips, benchmark/timing, etc.)
+    if subfeature
+      prefix = feature.split("/").first + "-"
+      return if specs.any? { |spec, _| spec.start_with?(prefix) }
+
+      # Don't warn if the feature is found outside the standard library
+      # (e.g., benchmark-ips's lib dir is on $LOAD_PATH but not in specs)
+      resolved = $LOAD_PATH.resolve_feature_path(feature) rescue nil
+      if resolved && !resolved[1].start_with?(LIBDIR, ARCHDIR)
+        return
+      end
+    end
+
+    return if WARNED[name]
+    WARNED[name] = true
+
+    level = RUBY_VERSION < SINCE[name] ? :warning : :error
+
+    if subfeature
+      "#{feature} is found in #{name}, which"
+    else
+      "#{feature} #{level == :warning ? "was loaded" : "used to be loaded"} from the standard library, but"
+    end + build_message(name, level)
+  end
+
+  def self.build_message(name, level)
+    msg = if level == :warning
+      " will no longer be part of the default gems starting from Ruby #{SINCE[name]}"
+    else
+      " is not part of the default gems since Ruby #{SINCE[name]}."
+    end
+
+    if defined?(Bundler)
+      motivation = level == :warning ? "silence this warning" : "fix this error"
+      msg += "\nYou can add #{name} to your Gemfile or gemspec to #{motivation}."
+
+      # We detect the gem name from caller_locations. First we walk until we find `require`
+      # then take the first frame that's not from `require`.
+      #
+      # Additionally, we need to skip Bootsnap and Zeitwerk if present, these
+      # gems decorate Kernel#require, so they are not really the ones issuing
+      # the require call users should be warned about. Those are upwards.
+      frames_to_skip = 3
+      location = nil
+      require_found = false
+      Thread.each_caller_location do |cl|
+        if frames_to_skip >= 1
+          frames_to_skip -= 1
+          next
+        end
+
+        if require_found
+          if cl.base_label != "require"
+            location = cl.path
+            break
+          end
+        else
+          if cl.base_label == "require"
+            require_found = true
+          end
+        end
+      end
+
+      if location && File.file?(location) && !location.start_with?(Gem::BUNDLED_GEMS::LIBDIR)
+        caller_gem = nil
+        Gem.path.each do |path|
+          if location =~ %r{#{path}/gems/([\w\-\.]+)}
+            caller_gem = $1
+            break
+          end
+        end
+        if caller_gem
+          msg += "\nAlso please contact the author of #{caller_gem} to request adding #{name} into its gemspec."
+        end
+      end
+    else
+      msg += " Install #{name} from RubyGems."
+    end
+
+    msg
+  end
+
+  def self.force_activate(gem)
+    require "bundler"
+    Bundler.reset!
+
+    # Build and activate a temporary definition containing the original gems + the requested gem
+    builder = Bundler::Dsl.new
+
+    lockfile = nil
+    if Bundler::SharedHelpers.in_bundle? && Bundler.definition.gemfiles.size > 0
+      Bundler.definition.gemfiles.each {|gemfile| builder.eval_gemfile(gemfile) }
+      lockfile = begin
+        Bundler.default_lockfile
+      rescue Bundler::GemfileNotFound
+        nil
+      end
+    else
+      # Fake BUNDLE_GEMFILE and BUNDLE_LOCKFILE to let checks pass
+      orig_gemfile = ENV["BUNDLE_GEMFILE"]
+      orig_lockfile = ENV["BUNDLE_LOCKFILE"]
+      Bundler::SharedHelpers.set_env "BUNDLE_GEMFILE", "Gemfile"
+      Bundler::SharedHelpers.set_env "BUNDLE_LOCKFILE", "Gemfile.lock"
+    end
+
+    builder.gem gem
+
+    definition = builder.to_definition(lockfile, nil)
+    definition.validate_runtime!
+
+    begin
+      orig_ui = Bundler.ui
+      orig_no_lock = Bundler::Definition.no_lock
+
+      ui = Bundler::UI::Shell.new
+      ui.level = "silent"
+      Bundler.ui = ui
+      Bundler::Definition.no_lock = true
+
+      Bundler::Runtime.new(nil, definition).setup
+    rescue Bundler::GemNotFound
+      warn "Failed to activate #{gem}, please install it with 'gem install #{gem}'"
+    ensure
+      ENV['BUNDLE_GEMFILE'] = orig_gemfile if orig_gemfile
+      ENV['BUNDLE_LOCKFILE'] = orig_lockfile if orig_lockfile
+      Bundler.ui = orig_ui
+      Bundler::Definition.no_lock = orig_no_lock
+    end
+  end
+end
+
+# for RubyGems without Bundler environment.
+# If loading library is not part of the default gems and the bundled gems, warn it.
+class LoadError
+  def message # :nodoc:
+    return super unless path
+
+    name = path.tr("/", "-")
+    if !defined?(Bundler) && Gem::BUNDLED_GEMS::SINCE[name] && !Gem::BUNDLED_GEMS::WARNED[name]
+      warn name + Gem::BUNDLED_GEMS.build_message(name, :error), uplevel: Gem::BUNDLED_GEMS.uplevel
+    end
+    super
+  end
+end
diff --git a/lib/bundler.rb b/lib/bundler.rb
new file mode 100644
index 0000000000..12dde90fc5
--- /dev/null
+++ b/lib/bundler.rb
@@ -0,0 +1,692 @@
+# frozen_string_literal: true
+
+require_relative "bundler/rubygems_ext"
+require_relative "bundler/vendored_fileutils"
+autoload :Pathname, "pathname" unless defined?(Pathname)
+require "rbconfig"
+
+require_relative "bundler/errors"
+require_relative "bundler/environment_preserver"
+require_relative "bundler/plugin"
+require_relative "bundler/rubygems_integration"
+require_relative "bundler/version"
+require_relative "bundler/current_ruby"
+require_relative "bundler/build_metadata"
+
+# Bundler provides a consistent environment for Ruby projects by
+# tracking and installing the exact gems and versions that are needed.
+#
+# Bundler is a part of Ruby's standard library.
+#
+# Bundler is used by creating _gemfiles_ listing all the project dependencies
+# and (optionally) their versions and then using
+#
+#   require 'bundler/setup'
+#
+# or Bundler.setup to setup environment where only specified gems and their
+# specified versions could be used.
+#
+# See {Bundler website}[https://bundler.io/docs.html] for extensive documentation
+# on gemfiles creation and Bundler usage.
+#
+# As a standard library inside project, Bundler could be used for introspection
+# of loaded and required modules.
+#
+module Bundler
+  environment_preserver = EnvironmentPreserver.from_env
+  ORIGINAL_ENV = environment_preserver.restore
+  environment_preserver.replace_with_backup
+  SUDO_MUTEX = Thread::Mutex.new
+
+  autoload :Checksum,               File.expand_path("bundler/checksum", __dir__)
+  autoload :CLI,                    File.expand_path("bundler/cli", __dir__)
+  autoload :CIDetector,             File.expand_path("bundler/ci_detector", __dir__)
+  autoload :CompactIndexClient,     File.expand_path("bundler/compact_index_client", __dir__)
+  autoload :Definition,             File.expand_path("bundler/definition", __dir__)
+  autoload :Dependency,             File.expand_path("bundler/dependency", __dir__)
+  autoload :Deprecate,              File.expand_path("bundler/deprecate", __dir__)
+  autoload :Digest,                 File.expand_path("bundler/digest", __dir__)
+  autoload :Dsl,                    File.expand_path("bundler/dsl", __dir__)
+  autoload :EndpointSpecification,  File.expand_path("bundler/endpoint_specification", __dir__)
+  autoload :Env,                    File.expand_path("bundler/env", __dir__)
+  autoload :Fetcher,                File.expand_path("bundler/fetcher", __dir__)
+  autoload :FeatureFlag,            File.expand_path("bundler/feature_flag", __dir__)
+  autoload :FREEBSD,                File.expand_path("bundler/constants", __dir__)
+  autoload :GemHelper,              File.expand_path("bundler/gem_helper", __dir__)
+  autoload :GemVersionPromoter,     File.expand_path("bundler/gem_version_promoter", __dir__)
+  autoload :Index,                  File.expand_path("bundler/index", __dir__)
+  autoload :Injector,               File.expand_path("bundler/injector", __dir__)
+  autoload :Installer,              File.expand_path("bundler/installer", __dir__)
+  autoload :LazySpecification,      File.expand_path("bundler/lazy_specification", __dir__)
+  autoload :LockfileParser,         File.expand_path("bundler/lockfile_parser", __dir__)
+  autoload :MatchRemoteMetadata,    File.expand_path("bundler/match_remote_metadata", __dir__)
+  autoload :Materialization,        File.expand_path("bundler/materialization", __dir__)
+  autoload :NULL,                   File.expand_path("bundler/constants", __dir__)
+  autoload :Override,               File.expand_path("bundler/override", __dir__)
+  autoload :ProcessLock,            File.expand_path("bundler/process_lock", __dir__)
+  autoload :RemoteSpecification,    File.expand_path("bundler/remote_specification", __dir__)
+  autoload :Resolver,               File.expand_path("bundler/resolver", __dir__)
+  autoload :Retry,                  File.expand_path("bundler/retry", __dir__)
+  autoload :RubyDsl,                File.expand_path("bundler/ruby_dsl", __dir__)
+  autoload :RubyVersion,            File.expand_path("bundler/ruby_version", __dir__)
+  autoload :Runtime,                File.expand_path("bundler/runtime", __dir__)
+  autoload :SelfManager,            File.expand_path("bundler/self_manager", __dir__)
+  autoload :Settings,               File.expand_path("bundler/settings", __dir__)
+  autoload :SharedHelpers,          File.expand_path("bundler/shared_helpers", __dir__)
+  autoload :Source,                 File.expand_path("bundler/source", __dir__)
+  autoload :SourceList,             File.expand_path("bundler/source_list", __dir__)
+  autoload :SourceMap,              File.expand_path("bundler/source_map", __dir__)
+  autoload :SpecSet,                File.expand_path("bundler/spec_set", __dir__)
+  autoload :StubSpecification,      File.expand_path("bundler/stub_specification", __dir__)
+  autoload :UI,                     File.expand_path("bundler/ui", __dir__)
+  autoload :URICredentialsFilter,   File.expand_path("bundler/uri_credentials_filter", __dir__)
+  autoload :URINormalizer,          File.expand_path("bundler/uri_normalizer", __dir__)
+  autoload :WINDOWS,                File.expand_path("bundler/constants", __dir__)
+  autoload :SafeMarshal,            File.expand_path("bundler/safe_marshal", __dir__)
+
+  class << self
+    def configure
+      @configure ||= configure_gem_home_and_path
+    end
+
+    def ui
+      (defined?(@ui) && @ui) || (self.ui = UI::Shell.new)
+    end
+
+    def ui=(ui)
+      Bundler.rubygems.ui = UI::RGProxy.new(ui)
+      @ui = ui
+    end
+
+    # Returns absolute path of where gems are installed on the filesystem.
+    def bundle_path
+      @bundle_path ||= Pathname.new(configured_bundle_path.path).expand_path(root)
+    end
+
+    def create_bundle_path
+      mkdir_p(bundle_path) unless bundle_path.exist?
+
+      @bundle_path = bundle_path.realpath
+    rescue Errno::EEXIST
+      raise PathError, "Could not install to path `#{bundle_path}` " \
+        "because a file already exists at that path. Either remove or rename the file so the directory can be created."
+    end
+
+    def configured_bundle_path
+      @configured_bundle_path ||= Bundler.settings.path.tap(&:validate!)
+    end
+
+    # Returns absolute location of where binstubs are installed to.
+    def bin_path
+      @bin_path ||= begin
+        path = Bundler.settings[:bin] || "bin"
+        path = Pathname.new(path).expand_path(root).expand_path
+        mkdir_p(path)
+        path
+      end
+    end
+
+    # Turns on the Bundler runtime. After +Bundler.setup+ call, all +load+ or
+    # +require+ of the gems would be allowed only if they are part of
+    # the Gemfile or Ruby's standard library. If the versions specified
+    # in Gemfile, only those versions would be loaded.
+    #
+    # Assuming Gemfile
+    #
+    #    gem 'first_gem', '= 1.0'
+    #    group :test do
+    #      gem 'second_gem', '= 1.0'
+    #    end
+    #
+    # The code using Bundler.setup works as follows:
+    #
+    #    require 'third_gem' # allowed, required from global gems
+    #    require 'first_gem' # allowed, loads the last installed version
+    #    Bundler.setup
+    #    require 'fourth_gem' # fails with LoadError
+    #    require 'second_gem' # loads exactly version 1.0
+    #
+    # +Bundler.setup+ can be called only once, all subsequent calls are no-op.
+    #
+    # If _groups_ list is provided, only gems from specified groups would
+    # be allowed (gems specified outside groups belong to special +:default+ group).
+    #
+    # To require all gems from Gemfile (or only some groups), see Bundler.require.
+    #
+    def setup(*groups)
+      # Return if all groups are already loaded
+      return @setup if defined?(@setup) && @setup
+
+      configure_custom_gemfile
+      definition.validate_runtime!
+
+      SharedHelpers.print_major_deprecations!
+
+      if groups.empty?
+        # Load all groups, but only once
+        @setup = load.setup
+      else
+        load.setup(*groups)
+      end
+    end
+
+    def auto_switch
+      self_manager.restart_with_locked_bundler_if_needed
+    end
+
+    # Automatically install dependencies if <tt>settings[:auto_install]</tt> exists.
+    # This is set through config cmd `bundle config set --global auto_install 1`.
+    #
+    # Note that this method `nil`s out the global Definition object, so it
+    # should be called first, before you instantiate anything like an
+    # `Installer` that'll keep a reference to the old one instead.
+    def auto_install
+      return unless Bundler.settings[:auto_install]
+
+      begin
+        definition.specs
+      rescue GemNotFound, GitError
+        ui.info "Automatically installing missing gems."
+        reset!
+        CLI::Install.new({}).run
+        reset!
+      end
+    end
+
+    # Setups Bundler environment (see Bundler.setup) if it is not already set,
+    # and loads all gems from groups specified. Unlike ::setup, can be called
+    # multiple times with different groups (if they were allowed by setup).
+    #
+    # Assuming Gemfile
+    #
+    #    gem 'first_gem', '= 1.0'
+    #    group :test do
+    #      gem 'second_gem', '= 1.0'
+    #    end
+    #
+    # The code will work as follows:
+    #
+    #    Bundler.setup # allow all groups
+    #    Bundler.require(:default) # requires only first_gem
+    #    # ...later
+    #    Bundler.require(:test)   # requires second_gem
+    #
+    def require(*groups)
+      setup(*groups).require(*groups)
+    end
+
+    def load
+      @load ||= Runtime.new(root, definition)
+    end
+
+    def environment
+      SharedHelpers.feature_removed! "Bundler.environment has been removed in favor of Bundler.load"
+    end
+
+    # Returns an instance of Bundler::Definition for given Gemfile and lockfile
+    #
+    # @param unlock [Hash, Boolean, nil] Gems that have been requested
+    #   to be updated or true if all gems should be updated
+    # @param lockfile [Pathname] Path to Gemfile.lock
+    # @return [Bundler::Definition]
+    def definition(unlock = nil, lockfile = default_lockfile)
+      @definition = nil if unlock
+      @definition ||= begin
+        configure
+        Definition.build(default_gemfile, lockfile, unlock)
+      end
+    end
+
+    def frozen_bundle?
+      frozen = Bundler.settings[:frozen]
+      return frozen unless frozen.nil?
+
+      Bundler.settings[:deployment]
+    end
+
+    def locked_gems
+      @locked_gems ||=
+        if defined?(@definition) && @definition
+          definition.locked_gems
+        elsif Bundler.default_lockfile.file?
+          lock = Bundler.read_file(Bundler.default_lockfile)
+          LockfileParser.new(lock)
+        end
+    end
+
+    def ruby_scope
+      "#{Bundler.rubygems.ruby_engine}/#{RbConfig::CONFIG["ruby_version"]}"
+    end
+
+    def user_home
+      @user_home ||= begin
+        home = Bundler.rubygems.user_home
+        bundle_home = home ? File.join(home, ".bundle") : nil
+
+        warning = if home.nil?
+          "Your home directory is not set."
+        elsif !File.directory?(home)
+          "`#{home}` is not a directory."
+        elsif !File.writable?(home) && (!File.directory?(bundle_home) || !File.writable?(bundle_home))
+          "`#{home}` is not writable."
+        end
+
+        if warning
+          Bundler.ui.warn "#{warning}\n"
+          user_home = tmp_home_path
+          Bundler.ui.warn "Bundler will use `#{user_home}' as your home directory temporarily.\n"
+          user_home
+        else
+          Pathname.new(home)
+        end
+      end
+    end
+
+    def user_bundle_path(dir = "home")
+      env_var, fallback = case dir
+                          when "home"
+                            ["BUNDLE_USER_HOME", proc { Pathname.new(user_home).join(".bundle") }]
+                          when "cache"
+                            ["BUNDLE_USER_CACHE", proc { user_bundle_path.join("cache") }]
+                          when "config"
+                            ["BUNDLE_USER_CONFIG", proc { user_bundle_path.join("config") }]
+                          when "plugin"
+                            ["BUNDLE_USER_PLUGIN", proc { user_bundle_path.join("plugin") }]
+                          else
+                            raise BundlerError, "Unknown user path requested: #{dir}"
+      end
+      # `fallback` will already be a Pathname, but Pathname.new() is
+      # idempotent so it's OK
+      Pathname.new(ENV.fetch(env_var, &fallback))
+    end
+
+    def user_cache
+      user_bundle_path("cache")
+    end
+
+    def home
+      bundle_path.join("bundler")
+    end
+
+    def install_path
+      home.join("gems")
+    end
+
+    def specs_path
+      bundle_path.join("specifications")
+    end
+
+    def root
+      @root ||= begin
+                  SharedHelpers.root
+                rescue GemfileNotFound
+                  bundle_dir = default_bundle_dir
+                  raise GemfileNotFound, "Could not locate Gemfile or .bundle/ directory" unless bundle_dir
+                  Pathname.new(File.expand_path("..", bundle_dir))
+                end
+    end
+
+    def app_config_path
+      if app_config = ENV["BUNDLE_APP_CONFIG"]
+        app_config_pathname = Pathname.new(app_config)
+
+        if app_config_pathname.absolute?
+          app_config_pathname
+        else
+          app_config_pathname.expand_path(root)
+        end
+      else
+        root.join(".bundle")
+      end
+    end
+
+    def app_cache(custom_path = nil)
+      path = custom_path || root
+      Pathname.new(path).join(Bundler.settings.app_cache_path)
+    end
+
+    def tmp(name = Process.pid.to_s)
+      Kernel.send(:require, "tmpdir")
+      Pathname.new(Dir.mktmpdir(["bundler", name]))
+    end
+
+    def rm_rf(path)
+      FileUtils.remove_entry_secure(path) if path && File.exist?(path)
+    end
+
+    def settings
+      @settings ||= Settings.new(app_config_path)
+    rescue GemfileNotFound
+      @settings = Settings.new
+    end
+
+    # @return [Hash] Environment present before Bundler was activated
+    def original_env
+      ORIGINAL_ENV.clone
+    end
+
+    def clean_env
+      removed_message =
+        "`Bundler.clean_env` has been removed in favor of `Bundler.unbundled_env`. " \
+        "If you instead want the environment before bundler was originally loaded, use `Bundler.original_env`"
+      Bundler::SharedHelpers.feature_removed!(removed_message)
+    end
+
+    # @return [Hash] Environment with all bundler-related variables removed
+    def unbundled_env
+      unbundle_env(original_env)
+    end
+
+    # Remove all bundler-related variables from ENV
+    def unbundle_env!
+      ENV.replace(unbundle_env(ENV))
+    end
+
+    # Run block with environment present before Bundler was activated
+    def with_original_env
+      with_env(original_env) { yield }
+    end
+
+    def with_clean_env
+      removed_message =
+        "`Bundler.with_clean_env` has been removed in favor of `Bundler.with_unbundled_env`. " \
+        "If you instead want the environment before bundler was originally loaded, use `Bundler.with_original_env`"
+      Bundler::SharedHelpers.feature_removed!(removed_message)
+    end
+
+    # Run block with all bundler-related variables removed
+    def with_unbundled_env
+      with_env(unbundled_env) { yield }
+    end
+
+    # Run subcommand with the environment present before Bundler was activated
+    def original_system(*args)
+      with_original_env { Kernel.system(*args) }
+    end
+
+    def clean_system(*args)
+      removed_message =
+        "`Bundler.clean_system` has been removed in favor of `Bundler.unbundled_system`. " \
+        "If you instead want to run the command in the environment before bundler was originally loaded, use `Bundler.original_system`"
+      Bundler::SharedHelpers.feature_removed!(removed_message)
+    end
+
+    # Run subcommand in an environment with all bundler related variables removed
+    def unbundled_system(*args)
+      with_unbundled_env { Kernel.system(*args) }
+    end
+
+    # Run a `Kernel.exec` to a subcommand with the environment present before Bundler was activated
+    def original_exec(*args)
+      with_original_env { Kernel.exec(*args) }
+    end
+
+    def clean_exec(*args)
+      removed_message =
+        "`Bundler.clean_exec` has been removed in favor of `Bundler.unbundled_exec`. " \
+        "If you instead want to exec to a command in the environment before bundler was originally loaded, use `Bundler.original_exec`"
+      Bundler::SharedHelpers.feature_removed!(removed_message)
+    end
+
+    # Run a `Kernel.exec` to a subcommand in an environment with all bundler related variables removed
+    def unbundled_exec(*args)
+      with_env(unbundled_env) { Kernel.exec(*args) }
+    end
+
+    def local_platform
+      return Gem::Platform::RUBY if Bundler.settings[:force_ruby_platform]
+      Gem::Platform.local
+    end
+
+    def generic_local_platform
+      Gem::Platform.generic(local_platform)
+    end
+
+    def default_gemfile
+      SharedHelpers.default_gemfile
+    end
+
+    def default_lockfile
+      SharedHelpers.default_lockfile
+    end
+
+    def default_bundle_dir
+      SharedHelpers.default_bundle_dir
+    end
+
+    def system_bindir
+      # Gem.bindir doesn't always return the location that RubyGems will install
+      # system binaries. If you put '-n foo' in your .gemrc, RubyGems will
+      # install binstubs there instead. Unfortunately, RubyGems doesn't expose
+      # that directory at all, so rather than parse .gemrc ourselves, we allow
+      # the directory to be set as well, via `bundle config set --local bindir foo`.
+      Bundler.settings[:system_bindir] || Bundler.rubygems.gem_bindir
+    end
+
+    def preferred_gemfile_name
+      Bundler.settings[:init_gems_rb] ? "gems.rb" : "Gemfile"
+    end
+
+    def use_system_gems?
+      configured_bundle_path.use_system_gems?
+    end
+
+    def mkdir_p(path)
+      SharedHelpers.filesystem_access(path, :create) do |p|
+        FileUtils.mkdir_p(p)
+      end
+    end
+
+    def which(executable)
+      executable_path = find_executable(executable)
+      return executable_path if executable_path
+
+      if (paths = ENV["PATH"])
+        quote = '"'
+        paths.split(File::PATH_SEPARATOR).find do |path|
+          path = path[1..-2] if path.start_with?(quote) && path.end_with?(quote)
+          executable_path = find_executable(File.expand_path(executable, path))
+          return executable_path if executable_path
+        end
+      end
+    end
+
+    def find_executable(path)
+      extensions = RbConfig::CONFIG["EXECUTABLE_EXTS"]&.split
+      extensions = [RbConfig::CONFIG["EXEEXT"]] unless extensions&.any?
+      candidates = extensions.map {|ext| "#{path}#{ext}" }
+
+      candidates.find {|candidate| File.file?(candidate) && File.executable?(candidate) }
+    end
+
+    def read_file(file)
+      SharedHelpers.filesystem_access(file, :read) do
+        File.open(file, "r:UTF-8", &:read)
+      end
+    end
+
+    def safe_load_marshal(data)
+      if Gem.respond_to?(:load_safe_marshal)
+        Gem.load_safe_marshal
+        begin
+          Gem::SafeMarshal.safe_load(data)
+        rescue Gem::SafeMarshal::Reader::Error, Gem::SafeMarshal::Visitors::ToRuby::Error => e
+          raise MarshalError, "#{e.class}: #{e.message}"
+        end
+      else
+        load_marshal(data, marshal_proc: SafeMarshal.proc)
+      end
+    end
+
+    def load_gemspec(file, validate = false)
+      @gemspec_cache ||= {}
+      key = File.expand_path(file)
+      @gemspec_cache[key] ||= load_gemspec_uncached(file, validate)
+      # Protect against caching side-effected gemspecs by returning a
+      # new instance each time.
+      @gemspec_cache[key]&.dup
+    end
+
+    def load_gemspec_uncached(file, validate = false)
+      path = Pathname.new(file)
+      contents = read_file(file)
+      spec = eval_gemspec(path, contents)
+      return unless spec
+      spec.loaded_from = path.expand_path.to_s
+      Bundler.rubygems.validate(spec) if validate
+      spec
+    end
+
+    def clear_gemspec_cache
+      @gemspec_cache = {}
+    end
+
+    def git_present?
+      return @git_present if defined?(@git_present)
+      @git_present = Bundler.which("git")
+    end
+
+    def feature_flag
+      @feature_flag ||= FeatureFlag.new(Bundler.settings[:simulate_version] || VERSION)
+    end
+
+    def reset!
+      reset_paths!
+      Plugin.reset!
+      reset_rubygems!
+    end
+
+    def reset_settings_and_root!
+      @settings = nil
+      @root = nil
+    end
+
+    def reset_paths!
+      @bin_path = nil
+      @bundle_path = nil
+      @configure = nil
+      @configured_bundle_path = nil
+      @definition = nil
+      @load = nil
+      @locked_gems = nil
+      @root = nil
+      @settings = nil
+      @setup = nil
+      @user_home = nil
+    end
+
+    def reset_rubygems!
+      return unless defined?(@rubygems) && @rubygems
+      rubygems.undo_replacements
+      rubygems.reset
+      @rubygems = nil
+    end
+
+    def configure_gem_home_and_path(path = bundle_path)
+      configure_gem_path
+      configure_gem_home(path)
+      Bundler.rubygems.clear_paths
+    end
+
+    def configure_custom_gemfile(custom_gemfile = nil)
+      custom_gemfile ||= Bundler.settings[:gemfile]
+
+      if custom_gemfile && !custom_gemfile.empty?
+        Bundler::SharedHelpers.set_env "BUNDLE_GEMFILE", File.expand_path(custom_gemfile)
+        reset_settings_and_root!
+      end
+    end
+
+    def self_manager
+      @self_manager ||= begin
+                          require_relative "bundler/self_manager"
+                          Bundler::SelfManager.new
+                        end
+    end
+
+    private
+
+    def unbundle_env(env)
+      if env.key?("BUNDLER_ORIG_MANPATH")
+        env["MANPATH"] = env["BUNDLER_ORIG_MANPATH"]
+      end
+
+      env.delete_if {|k, _| k[0, 7] == "BUNDLE_" }
+      env.delete("BUNDLER_SETUP")
+
+      if env.key?("RUBYOPT")
+        rubyopt = env["RUBYOPT"].split(" ")
+        rubyopt.delete("-r#{File.expand_path("bundler/setup", __dir__)}")
+        rubyopt.delete("-rbundler/setup")
+        env["RUBYOPT"] = rubyopt.join(" ")
+      end
+
+      if env.key?("RUBYLIB")
+        rubylib = env["RUBYLIB"].split(File::PATH_SEPARATOR)
+        rubylib.delete(__dir__)
+        env["RUBYLIB"] = rubylib.join(File::PATH_SEPARATOR)
+      end
+
+      env
+    end
+
+    def load_marshal(data, marshal_proc: nil)
+      Marshal.load(data, marshal_proc)
+    rescue TypeError => e
+      raise MarshalError, "#{e.class}: #{e.message}"
+    end
+
+    def eval_yaml_gemspec(path, contents)
+      Kernel.require "psych"
+
+      Gem::Specification.from_yaml(contents)
+    end
+
+    def eval_gemspec(path, contents)
+      if contents.start_with?("---") # YAML header
+        eval_yaml_gemspec(path, contents)
+      else
+        # Eval the gemspec from its parent directory, because some gemspecs
+        # depend on "./" relative paths.
+        SharedHelpers.chdir(path.dirname.to_s) do
+          eval(contents, TOPLEVEL_BINDING.dup, path.expand_path.to_s)
+        end
+      end
+    rescue ScriptError, StandardError => e
+      msg = "There was an error while loading `#{path.basename}`: #{e.message}"
+
+      raise GemspecError, Dsl::DSLError.new(msg, path.to_s, e.backtrace, contents)
+    end
+
+    def configure_gem_path
+      unless use_system_gems?
+        # this needs to be empty string to cause
+        # PathSupport.split_gem_path to only load up the
+        # Bundler --path setting as the GEM_PATH.
+        Bundler::SharedHelpers.set_env "GEM_PATH", ""
+      end
+    end
+
+    def configure_gem_home(path)
+      Bundler::SharedHelpers.set_env "GEM_HOME", path.to_s
+    end
+
+    def tmp_home_path
+      Kernel.send(:require, "tmpdir")
+      SharedHelpers.filesystem_access(Dir.tmpdir) do
+        path = Bundler.tmp
+        at_exit { Bundler.rm_rf(path) }
+        path
+      end
+    end
+
+    # @param env [Hash]
+    def with_env(env)
+      backup = ENV.to_hash
+      ENV.replace(env)
+      yield
+    ensure
+      ENV.replace(backup)
+    end
+  end
+end
diff --git a/lib/bundler/.document b/lib/bundler/.document
new file mode 100644
index 0000000000..238bbd8705
--- /dev/null
+++ b/lib/bundler/.document
@@ -0,0 +1 @@
+# not in RDoc
diff --git a/lib/bundler/build_metadata.rb b/lib/bundler/build_metadata.rb
new file mode 100644
index 0000000000..49d2518078
--- /dev/null
+++ b/lib/bundler/build_metadata.rb
@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+module Bundler
+  # Represents metadata from when the Bundler gem was built.
+  module BuildMetadata
+    # begin ivars
+    @built_at = nil
+    # end ivars
+
+    # A hash representation of the build metadata.
+    def self.to_h
+      {
+        "Timestamp" => timestamp,
+        "Git SHA" => git_commit_sha,
+      }
+    end
+
+    # A timestamp representing the date the bundler gem was built, or the
+    # current time if never built
+    def self.timestamp
+      @timestamp ||= @built_at || Time.now.utc.strftime("%Y-%m-%d").freeze
+    end
+
+    # A string representing the date the bundler gem was built.
+    def self.built_at
+      @built_at
+    end
+
+    # The SHA for the git commit the bundler gem was built from.
+    def self.git_commit_sha
+      return @git_commit_sha if instance_variable_defined? :@git_commit_sha
+
+      # If Bundler has been installed without its .git directory and without a
+      # commit instance variable then we can't determine its commits SHA.
+      git_dir = File.expand_path("../../../.git", __dir__)
+      if File.directory?(git_dir)
+        return @git_commit_sha = IO.popen(%w[git rev-parse --short HEAD], { chdir: git_dir }, &:read).strip.freeze
+      end
+
+      @git_commit_sha ||= "unknown"
+    end
+  end
+end
diff --git a/lib/bundler/bundler.gemspec b/lib/bundler/bundler.gemspec
new file mode 100644
index 0000000000..49319e81b4
--- /dev/null
+++ b/lib/bundler/bundler.gemspec
@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+begin
+  require_relative "lib/bundler/version"
+rescue LoadError
+  # for Ruby core repository
+  require_relative "version"
+end
+
+Gem::Specification.new do |s|
+  s.name        = "bundler"
+  s.version     = Bundler::VERSION
+  s.license     = "MIT"
+  s.authors     = [
+    "André Arko", "Samuel Giddins", "Colby Swandale", "Hiroshi Shibata",
+    "David Rodríguez", "Grey Baker", "Stephanie Morillo", "Chris Morris", "James Wen", "Tim Moore",
+    "André Medeiros", "Jessica Lynn Suttles", "Terence Lee", "Carl Lerche",
+    "Yehuda Katz"
+  ]
+  s.email       = ["team@bundler.io"]
+  s.homepage    = "https://bundler.io"
+  s.summary     = "The best way to manage your application's dependencies"
+  s.description = "Bundler manages an application's dependencies through its entire life, across many machines, systematically and repeatably"
+
+  s.metadata = {
+    "bug_tracker_uri" => "https://github.com/ruby/rubygems/issues?q=is%3Aopen+is%3Aissue+label%3ABundler",
+    "changelog_uri" => "https://github.com/ruby/rubygems/blob/master/bundler/CHANGELOG.md",
+    "homepage_uri" => "https://bundler.io/",
+    "source_code_uri" => "https://github.com/ruby/rubygems/tree/master/bundler",
+  }
+
+  s.required_ruby_version     = ">= 3.2.0"
+
+  # It should match the RubyGems version shipped with `required_ruby_version` above
+  s.required_rubygems_version = ">= 3.4.1"
+
+  s.files = Dir.glob("lib/bundler{.rb,/**/*}", File::FNM_DOTMATCH).reject {|f| File.directory?(f) }
+
+  # include the gemspec itself because warbler breaks w/o it
+  s.files += %w[lib/bundler/bundler.gemspec]
+
+  s.bindir        = "exe"
+  s.executables   = %w[bundle bundler]
+  s.require_paths = ["lib"]
+end
diff --git a/lib/bundler/capistrano.rb b/lib/bundler/capistrano.rb
new file mode 100644
index 0000000000..6d2437d895
--- /dev/null
+++ b/lib/bundler/capistrano.rb
@@ -0,0 +1,4 @@
+# frozen_string_literal: true
+
+require_relative "shared_helpers"
+Bundler::SharedHelpers.feature_removed! "The Bundler task for Capistrano. Please use https://github.com/capistrano/bundler"
diff --git a/lib/bundler/checksum.rb b/lib/bundler/checksum.rb
new file mode 100644
index 0000000000..ce05818bb0
--- /dev/null
+++ b/lib/bundler/checksum.rb
@@ -0,0 +1,270 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Checksum
+    ALGO_SEPARATOR = "="
+    DEFAULT_ALGORITHM = "sha256"
+    private_constant :DEFAULT_ALGORITHM
+    DEFAULT_BLOCK_SIZE = 16_384
+    private_constant :DEFAULT_BLOCK_SIZE
+
+    class << self
+      def from_gem_package(gem_package, algo = DEFAULT_ALGORITHM)
+        return if Bundler.settings[:disable_checksum_validation]
+        return unless source = gem_package.instance_variable_get(:@gem)
+        return unless source.respond_to?(:with_read_io)
+
+        source.with_read_io do |io|
+          from_gem(io, source.path)
+        ensure
+          io.rewind
+        end
+      end
+
+      def from_gem(io, pathname, algo = DEFAULT_ALGORITHM)
+        digest = Bundler::SharedHelpers.digest(algo.upcase).new
+        buf = String.new(capacity: DEFAULT_BLOCK_SIZE)
+        digest << io.readpartial(DEFAULT_BLOCK_SIZE, buf) until io.eof?
+        Checksum.new(algo, digest.hexdigest!, Source.new(:gem, pathname))
+      end
+
+      def from_api(digest, source_uri, algo = DEFAULT_ALGORITHM)
+        return if Bundler.settings[:disable_checksum_validation]
+
+        Checksum.new(algo, to_hexdigest(digest, algo), Source.new(:api, source_uri))
+      end
+
+      def from_lock(lock_checksum, lockfile_location)
+        algo, digest = lock_checksum.strip.split(ALGO_SEPARATOR, 2)
+        Checksum.new(algo, to_hexdigest(digest, algo), Source.new(:lock, lockfile_location))
+      end
+
+      def to_hexdigest(digest, algo = DEFAULT_ALGORITHM)
+        return digest unless algo == DEFAULT_ALGORITHM
+        return digest if digest.match?(/\A[0-9a-f]{64}\z/i)
+
+        if digest.match?(%r{\A[-0-9a-z_+/]{43}={0,2}\z}i)
+          digest = digest.tr("-_", "+/") # fix urlsafe base64
+          digest.unpack1("m0").unpack1("H*")
+        else
+          raise ArgumentError, "#{digest.inspect} is not a valid SHA256 hex or base64 digest"
+        end
+      end
+    end
+
+    attr_reader :algo, :digest, :sources
+
+    def initialize(algo, digest, source)
+      @algo = algo
+      @digest = digest
+      @sources = [source]
+    end
+
+    def ==(other)
+      match?(other) && other.sources == sources
+    end
+
+    alias_method :eql?, :==
+
+    def same_source?(other)
+      sources.include?(other.sources.first)
+    end
+
+    def match?(other)
+      other.is_a?(self.class) && other.digest == digest && other.algo == algo
+    end
+
+    def hash
+      digest.hash
+    end
+
+    def to_s
+      "#{to_lock} (from #{sources.first}#{", ..." if sources.size > 1})"
+    end
+
+    def to_lock
+      "#{algo}#{ALGO_SEPARATOR}#{digest}"
+    end
+
+    def merge!(other)
+      return nil unless match?(other)
+
+      @sources.concat(other.sources).uniq!
+      self
+    end
+
+    def formatted_sources
+      sources.join("\n    and ").concat("\n")
+    end
+
+    def removable?
+      sources.all?(&:removable?)
+    end
+
+    def removal_instructions
+      msg = +""
+      i = 1
+      sources.each do |source|
+        msg << "  #{i}. #{source.removal}\n"
+        i += 1
+      end
+      msg << "  #{i}. run `bundle install`\n"
+    end
+
+    def inspect
+      abbr = "#{algo}#{ALGO_SEPARATOR}#{digest[0, 8]}"
+      from = "from #{sources.join(" and ")}"
+      "#<#{self.class}:#{object_id} #{abbr} #{from}>"
+    end
+
+    class Source
+      attr_reader :type, :location
+
+      def initialize(type, location)
+        @type = type
+        @location = location
+      end
+
+      def removable?
+        [:lock, :gem].include?(type)
+      end
+
+      def ==(other)
+        other.is_a?(self.class) && other.type == type && other.location == location
+      end
+
+      # phrased so that the usual string format is grammatically correct
+      #   rake (10.3.2) sha256=abc123 from #{to_s}
+      def to_s
+        case type
+        when :lock
+          "the lockfile CHECKSUMS at #{location}"
+        when :gem
+          "the gem at #{location}"
+        when :api
+          "the API at #{location}"
+        else
+          "#{location} (#{type})"
+        end
+      end
+
+      # A full sentence describing how to remove the checksum
+      def removal
+        case type
+        when :lock
+          "remove the matching checksum in #{location}"
+        when :gem
+          "remove the gem at #{location}"
+        when :api
+          "checksums from #{location} cannot be locally modified, you may need to update your sources"
+        else
+          "remove #{location} (#{type})"
+        end
+      end
+    end
+
+    class Store
+      attr_reader :store
+      protected :store
+
+      def initialize
+        @store = {}
+        @store_mutex = Mutex.new
+      end
+
+      def inspect
+        "#<#{self.class}:#{object_id} size=#{store.size}>"
+      end
+
+      # Replace when the new checksum is from the same source.
+      # The primary purpose is registering checksums from gems where there are
+      # duplicates of the same gem (according to full_name) in the index.
+      #
+      # In particular, this is when 2 gems have two similar platforms, e.g.
+      # "darwin20" and "darwin-20", both of which resolve to darwin-20.
+      # In the Index, the later gem replaces the former, so we do that here.
+      #
+      # However, if the new checksum is from a different source, we register like normal.
+      # This ensures a mismatch error where there are multiple top level sources
+      # that contain the same gem with different checksums.
+      def replace(spec, checksum)
+        return unless checksum
+
+        lock_name = spec.lock_name
+        @store_mutex.synchronize do
+          existing = fetch_checksum(lock_name, checksum.algo)
+          if !existing || existing.same_source?(checksum)
+            store_checksum(lock_name, checksum)
+          else
+            merge_checksum(lock_name, checksum, existing)
+          end
+        end
+      end
+
+      def missing?(spec)
+        @store[spec.lock_name].nil?
+      end
+
+      def empty?(spec)
+        return false unless spec.source.is_a?(Bundler::Source::Rubygems)
+
+        @store[spec.lock_name].empty?
+      end
+
+      def register(spec, checksum)
+        register_checksum(spec.lock_name, checksum)
+      end
+
+      def merge!(other)
+        other.store.each do |lock_name, checksums|
+          checksums.each do |_algo, checksum|
+            register_checksum(lock_name, checksum)
+          end
+        end
+      end
+
+      def to_lock(spec)
+        lock_name = spec.lock_name
+        checksums = @store[lock_name]
+        if checksums&.any?
+          "#{lock_name} #{checksums.values.map(&:to_lock).sort.join(",")}"
+        else
+          lock_name
+        end
+      end
+
+      private
+
+      def register_checksum(lock_name, checksum)
+        @store_mutex.synchronize do
+          if checksum
+            existing = fetch_checksum(lock_name, checksum.algo)
+            if existing
+              merge_checksum(lock_name, checksum, existing)
+            else
+              store_checksum(lock_name, checksum)
+            end
+          else
+            init_checksum(lock_name)
+          end
+        end
+      end
+
+      def merge_checksum(lock_name, checksum, existing)
+        existing.merge!(checksum) || raise(ChecksumMismatchError.new(lock_name, existing, checksum))
+      end
+
+      def store_checksum(lock_name, checksum)
+        init_checksum(lock_name)[checksum.algo] = checksum
+      end
+
+      def init_checksum(lock_name)
+        @store[lock_name] ||= {}
+      end
+
+      def fetch_checksum(lock_name, algo)
+        @store[lock_name]&.fetch(algo, nil)
+      end
+    end
+  end
+end
diff --git a/lib/bundler/ci_detector.rb b/lib/bundler/ci_detector.rb
new file mode 100644
index 0000000000..e5fedbdea8
--- /dev/null
+++ b/lib/bundler/ci_detector.rb
@@ -0,0 +1,75 @@
+# frozen_string_literal: true
+
+module Bundler
+  module CIDetector
+    # NOTE: Any changes made here will need to be made to both lib/rubygems/ci_detector.rb and
+    # bundler/lib/bundler/ci_detector.rb (which are enforced duplicates).
+    # TODO: Drop that duplication once bundler drops support for RubyGems 3.4
+    #
+    # ## Recognized CI providers, their signifiers, and the relevant docs ##
+    #
+    # Travis CI   - CI, TRAVIS            https://docs.travis-ci.com/user/environment-variables/#default-environment-variables
+    # Cirrus CI   - CI, CIRRUS_CI         https://cirrus-ci.org/guide/writing-tasks/#environment-variables
+    # Circle CI   - CI, CIRCLECI          https://circleci.com/docs/variables/#built-in-environment-variables
+    # Gitlab CI   - CI, GITLAB_CI         https://docs.gitlab.com/ee/ci/variables/
+    # AppVeyor    - CI, APPVEYOR          https://www.appveyor.com/docs/environment-variables/
+    # CodeShip    - CI_NAME               https://docs.cloudbees.com/docs/cloudbees-codeship/latest/pro-builds-and-configuration/environment-variables#_default_environment_variables
+    # dsari       - CI, DSARI             https://github.com/rfinnie/dsari#running
+    # Jenkins     - BUILD_NUMBER          https://www.jenkins.io/doc/book/pipeline/jenkinsfile/#using-environment-variables
+    # TeamCity    - TEAMCITY_VERSION      https://www.jetbrains.com/help/teamcity/predefined-build-parameters.html#Predefined+Server+Build+Parameters
+    # Appflow     - CI_BUILD_ID           https://ionic.io/docs/appflow/automation/environments#predefined-environments
+    # TaskCluster - TASKCLUSTER_ROOT_URL  https://docs.taskcluster.net/docs/manual/design/env-vars
+    # Semaphore   - CI, SEMAPHORE         https://docs.semaphoreci.com/ci-cd-environment/environment-variables/
+    # BuildKite   - CI, BUILDKITE         https://buildkite.com/docs/pipelines/environment-variables
+    # GoCD        - GO_SERVER_URL         https://docs.gocd.org/current/faq/dev_use_current_revision_in_build.html
+    # GH Actions  - CI, GITHUB_ACTIONS    https://docs.github.com/en/actions/learn-github-actions/variables#default-environment-variables
+    #
+    # ### Some "standard" ENVs that multiple providers may set ###
+    #
+    # * CI - this is set by _most_ (but not all) CI providers now; it's approaching a standard.
+    # * CI_NAME - Not as frequently used, but some providers set this to specify their own name
+
+    # Any of these being set is a reasonably reliable indicator that we are
+    # executing in a CI environment.
+    ENV_INDICATORS = [
+      "CI",
+      "CI_NAME",
+      "CONTINUOUS_INTEGRATION",
+      "BUILD_NUMBER",
+      "CI_APP_ID",
+      "CI_BUILD_ID",
+      "CI_BUILD_NUMBER",
+      "RUN_ID",
+      "TASKCLUSTER_ROOT_URL",
+    ].freeze
+
+    # For each CI, this env suffices to indicate that we're on _that_ CI's
+    # containers. (A few of them only supply a CI_NAME variable, which is also
+    # nice). And if they set "CI" but we can't tell which one they are, we also
+    # want to know that - a bare "ci" without another token tells us as much.
+    ENV_DESCRIPTORS = {
+      "TRAVIS" => "travis",
+      "CIRCLECI" => "circle",
+      "CIRRUS_CI" => "cirrus",
+      "DSARI" => "dsari",
+      "SEMAPHORE" => "semaphore",
+      "JENKINS_URL" => "jenkins",
+      "BUILDKITE" => "buildkite",
+      "GO_SERVER_URL" => "go",
+      "GITLAB_CI" => "gitlab",
+      "GITHUB_ACTIONS" => "github",
+      "TASKCLUSTER_ROOT_URL" => "taskcluster",
+      "CI" => "ci",
+    }.freeze
+
+    def self.ci?
+      ENV_INDICATORS.any? {|var| ENV.include?(var) }
+    end
+
+    def self.ci_strings
+      matching_names = ENV_DESCRIPTORS.select {|env, _| ENV[env] }.values
+      matching_names << ENV["CI_NAME"].downcase if ENV["CI_NAME"]
+      matching_names.reject(&:empty?).sort.uniq
+    end
+  end
+end
diff --git a/lib/bundler/cli.rb b/lib/bundler/cli.rb
new file mode 100644
index 0000000000..9d8a68fff9
--- /dev/null
+++ b/lib/bundler/cli.rb
@@ -0,0 +1,830 @@
+# frozen_string_literal: true
+
+require_relative "vendored_thor"
+
+module Bundler
+  class CLI < Thor
+    require_relative "cli/common"
+    require_relative "cli/install"
+
+    package_name "Bundler"
+
+    AUTO_INSTALL_CMDS = %w[show binstubs outdated exec open console licenses clean].freeze
+    PARSEABLE_COMMANDS = %w[check config help exec platform show version].freeze
+    EXTENSIONS = ["c", "rust", "go"].freeze
+
+    COMMAND_ALIASES = {
+      "check" => "c",
+      "install" => "i",
+      "plugin" => "",
+      "list" => "ls",
+      "exec" => ["e", "ex", "exe"],
+      "cache" => ["package", "pack"],
+      "version" => ["-v", "--version"],
+    }.freeze
+
+    def self.start(*)
+      check_invalid_ext_option(ARGV) if ARGV.include?("--ext")
+
+      super
+    ensure
+      Bundler::SharedHelpers.print_major_deprecations!
+    end
+
+    def self.dispatch(*)
+      super do |i|
+        i.send(:print_command)
+        i.send(:warn_on_outdated_bundler)
+      end
+    end
+
+    def self.all_aliases
+      @all_aliases ||= begin
+                         command_aliases = {}
+
+                         COMMAND_ALIASES.each do |name, aliases|
+                           Array(aliases).each do |one_alias|
+                             command_aliases[one_alias] = name
+                           end
+                         end
+
+                         command_aliases
+                       end
+    end
+
+    def self.aliases_for(command_name)
+      COMMAND_ALIASES.select {|k, _| k == command_name }.invert
+    end
+
+    def initialize(*args)
+      super
+
+      current_cmd = args.last[:current_command].name
+
+      # `bundle config` manages stored settings, so avoid promoting settings
+      # like `gemfile` or `lockfile` to environment variables before it runs.
+      unless current_cmd == "config"
+        Bundler.configure_custom_gemfile(options[:gemfile])
+
+        # lock --lockfile works differently than install --lockfile
+        unless current_cmd == "lock"
+          custom_lockfile = options[:lockfile] || ENV["BUNDLE_LOCKFILE"] || Bundler.settings[:lockfile]
+          if custom_lockfile && !custom_lockfile.empty?
+            Bundler::SharedHelpers.set_env "BUNDLE_LOCKFILE", File.expand_path(custom_lockfile)
+            reset_settings = true
+          end
+        end
+      end
+
+      Bundler.reset_settings_and_root! if reset_settings
+
+      Bundler.auto_switch
+
+      Bundler.settings.set_command_option_if_given :retry, options[:retry]
+
+      Bundler.auto_install if AUTO_INSTALL_CMDS.include?(current_cmd)
+    rescue UnknownArgumentError => e
+      raise InvalidOption, e.message
+    ensure
+      self.options ||= {}
+      unprinted_warnings = Bundler.ui.unprinted_warnings
+      Bundler.ui = UI::Shell.new(options)
+      Bundler.ui.level = "debug" if options[:verbose] || Bundler.settings[:verbose]
+      unprinted_warnings.each {|w| Bundler.ui.warn(w) }
+    end
+
+    check_unknown_options!(except: [:config, :exec])
+    stop_on_unknown_option! :exec
+
+    desc "cli_help", "Prints a summary of bundler commands", hide: true
+    def cli_help
+      version
+      Bundler.ui.info "\n"
+
+      primary_commands = ["install", "update", "cache", "exec", "config", "help"]
+
+      list = self.class.printable_commands(true)
+      by_name = list.group_by {|name, _message| name.match(/^bundler? (\w+)/)[1] }
+      utilities = by_name.keys.sort - primary_commands
+      primary_commands.map! {|name| (by_name[name] || raise("no primary command #{name}")).first }
+      utilities.map! {|name| by_name[name].first }
+
+      shell.say "Bundler commands:\n\n"
+
+      shell.say "  Primary commands:\n"
+      shell.print_table(primary_commands, indent: 4, truncate: true)
+      shell.say
+      shell.say "  Utilities:\n"
+      shell.print_table(utilities, indent: 4, truncate: true)
+      shell.say
+      self.class.send(:class_options_help, shell)
+    end
+
+    desc "install_or_cli_help", "Deprecated alias of install", hide: true
+    def install_or_cli_help
+      Bundler.ui.warn <<~MSG
+        `bundle install_or_cli_help` is a deprecated alias of `bundle install`.
+        It might be called due to the 'default_cli_command' being set to 'install_or_cli_help',
+        if so fix that by running `bundle config set default_cli_command install --global`.
+      MSG
+      invoke_other_command("install")
+    end
+
+    def self.default_command(meth = nil)
+      return super if meth
+
+      unless Bundler.settings[:default_cli_command]
+        Bundler.ui.info <<~MSG
+          In a future version of Bundler, running `bundle` without argument will no longer run `bundle install`.
+          Instead, the `cli_help` command will be displayed. Please use `bundle install` explicitly for scripts like CI/CD.
+          You can use the future behavior now with `bundle config set default_cli_command cli_help --global`,
+          or you can continue to use the current behavior with `bundle config set default_cli_command install --global`.
+          This message will be removed after a default_cli_command value is set.
+
+        MSG
+      end
+
+      Bundler.settings[:default_cli_command] || "install"
+    end
+
+    class_option "no-color", type: :boolean, desc: "Disable colorization in output"
+    class_option "retry", type: :numeric, aliases: "-r", banner: "NUM",
+                          desc: "Specify the number of times you wish to attempt network commands"
+    class_option "verbose", type: :boolean, desc: "Enable verbose output mode", aliases: "-V"
+
+    def help(cli = nil)
+      cli = self.class.all_aliases[cli] if self.class.all_aliases[cli]
+
+      if Bundler.settings[:plugins] && Bundler::Plugin.command?(cli) && !self.class.all_commands.key?(cli)
+        return Bundler::Plugin.exec_command(cli, ["--help"])
+      end
+
+      case cli
+      when "gemfile" then command = "gemfile"
+      when nil       then command = "bundle"
+      else command = "bundle-#{cli}"
+      end
+
+      man_path = File.expand_path("man", __dir__)
+      man_pages = Hash[Dir.glob(File.join(man_path, "**", "*")).grep(/.*\.\d*\Z/).collect do |f|
+        [File.basename(f, ".*"), f]
+      end]
+
+      if man_pages.include?(command)
+        man_page = man_pages[command]
+        if Bundler.which("man") && !man_path.match?(%r{^(?:file:/.+!|uri:classloader:)/META-INF/jruby.home/.+})
+          Kernel.exec("man", man_page)
+        else
+          puts File.read("#{man_path}/#{File.basename(man_page)}.ronn")
+        end
+      elsif command_path = Bundler.which("bundler-#{cli}")
+        Kernel.exec(command_path, "--help")
+      else
+        super
+      end
+    end
+
+    def self.handle_no_command_error(command, has_namespace = $thor_runner)
+      if Bundler.settings[:plugins] && Bundler::Plugin.command?(command)
+        return Bundler::Plugin.exec_command(command, ARGV[1..-1])
+      end
+
+      return super unless command_path = Bundler.which("bundler-#{command}")
+
+      Kernel.exec(command_path, *ARGV[1..-1])
+    end
+
+    desc "init [OPTIONS]", "Generates a Gemfile into the current working directory"
+    long_desc <<-D
+      Init generates a default Gemfile in the current working directory. When adding a
+      Gemfile to a gem with a gemspec, the --gemspec option will automatically add each
+      dependency listed in the gemspec file to the newly created Gemfile.
+    D
+    method_option "gemspec", type: :string, banner: "Use the specified .gemspec to create the Gemfile"
+    method_option "gemfile", type: :string, banner: "Use the specified name for the gemfile instead of 'Gemfile'"
+    def init
+      require_relative "cli/init"
+      Init.new(options.dup).run
+    end
+
+    desc "check [OPTIONS]", "Checks if the dependencies listed in Gemfile are satisfied by currently installed gems"
+    long_desc <<-D
+      Check searches the local machine for each of the gems requested in the Gemfile. If
+      all gems are found, Bundler prints a success message and exits with a status of 0.
+      If not, the first missing gem is listed and Bundler exits status 1.
+    D
+    method_option "dry-run", type: :boolean, default: false, banner: "Lock the Gemfile"
+    method_option "gemfile", type: :string, banner: "Use the specified gemfile instead of Gemfile"
+    method_option "path", type: :string, banner: "Specify a different path than the system default, namely, $BUNDLE_PATH or $GEM_HOME (removed)"
+    def check
+      remembered_flag_deprecation("path")
+
+      require_relative "cli/check"
+      Check.new(options).run
+    end
+
+    map aliases_for("check")
+
+    desc "remove [GEM [GEM ...]]", "Removes gems from the Gemfile"
+    long_desc <<-D
+      Removes the given gems from the Gemfile while ensuring that the resulting Gemfile is still valid. If the gem is not found, Bundler prints a error message and if gem could not be removed due to any reason Bundler will display a warning.
+    D
+    method_option "install", type: :boolean, banner: "Runs 'bundle install' after removing the gems from the Gemfile (removed)"
+    def remove(*gems)
+      if ARGV.include?("--install")
+        removed_message = "The `--install` flag has been removed. `bundle install` is triggered by default."
+        raise InvalidOption, removed_message
+      end
+
+      require_relative "cli/remove"
+      Remove.new(gems, options).run
+    end
+
+    desc "install [OPTIONS]", "Install the current environment to the system"
+    long_desc <<-D
+      Install will install all of the gems in the current bundle, making them available
+      for use. In a freshly checked out repository, this command will give you the same
+      gem versions as the last person who updated the Gemfile and ran `bundle update`.
+
+      Passing [DIR] to install (e.g. vendor) will cause the unpacked gems to be installed
+      into the [DIR] directory rather than into system gems.
+
+      If the bundle has already been installed, bundler will tell you so and then exit.
+    D
+    method_option "binstubs", type: :string, lazy_default: "bin", banner: "Generate bin stubs for bundled gems to ./bin (removed)"
+    method_option "clean", type: :boolean, banner: "Run bundle clean automatically after install (removed)"
+    method_option "deployment", type: :boolean, banner: "Install using defaults tuned for deployment environments (removed)"
+    method_option "frozen", type: :boolean, banner: "Do not allow the Gemfile.lock to be updated after this install (removed)"
+    method_option "full-index", type: :boolean, banner: "Fall back to using the single-file index of all gems"
+    method_option "gemfile", type: :string, banner: "Use the specified gemfile instead of Gemfile"
+    method_option "jobs", aliases: "-j", type: :numeric, banner: "Specify the number of jobs to run in parallel"
+    method_option "local", type: :boolean, banner: "Do not attempt to fetch gems remotely and use the gem cache instead"
+    method_option "lockfile", type: :string, banner: "Use the specified lockfile instead of the default."
+    method_option "prefer-local", type: :boolean, banner: "Only attempt to fetch gems remotely if not present locally, even if newer versions are available remotely"
+    method_option "no-cache", type: :boolean, banner: "Don't update the existing gem cache."
+    method_option "no-lock", type: :boolean, banner: "Don't create a lockfile."
+    method_option "force", type: :boolean, aliases: "--redownload", banner: "Force reinstalling every gem, even if already installed"
+    method_option "no-prune", type: :boolean, banner: "Don't remove stale gems from the cache (removed)."
+    method_option "path", type: :string, banner: "Specify a different path than the system default, namely, $BUNDLE_PATH or $GEM_HOME (removed)."
+    method_option "quiet", type: :boolean, banner: "Only output warnings and errors."
+    method_option "shebang", type: :string, banner: "Specify a different shebang executable name than the default, usually 'ruby' (removed)"
+    method_option "standalone", type: :array, lazy_default: [], banner: "Make a bundle that can work without the Bundler runtime"
+    method_option "system", type: :boolean, banner: "Install to the system location ($BUNDLE_PATH or $GEM_HOME) even if the bundle was previously installed somewhere else for this application (removed)"
+    method_option "trust-policy", alias: "P", type: :string, banner: "Gem trust policy (like gem install -P). Must be one of #{Bundler.rubygems.security_policy_keys.join("|")}"
+    method_option "target-rbconfig", type: :string, banner: "Path to rbconfig.rb for the deployment target platform"
+    method_option "without", type: :array, banner: "Exclude gems that are part of the specified named group (removed)."
+    method_option "with", type: :array, banner: "Include gems that are part of the specified named group (removed)."
+    method_option "cooldown", type: :numeric, banner: "Only consider gem versions published at least N days ago. Use 0 to disable."
+    def install
+      %w[clean deployment frozen no-prune path shebang without with].each do |option|
+        remembered_flag_deprecation(option)
+      end
+
+      print_remembered_flag_deprecation("--system", "path.system", "true") if ARGV.include?("--system")
+
+      remembered_flag_deprecation("deployment", negative: true)
+
+      if ARGV.include?("--binstubs")
+        removed_message = "The --binstubs option has been removed in favor of `bundle binstubs --all`"
+        raise InvalidOption, removed_message
+      end
+
+      require_relative "cli/install"
+      options = self.options.dup
+      options["lockfile"] ||= ENV["BUNDLE_LOCKFILE"]
+      Bundler.settings.temporary(no_install: false) do
+        Install.new(options).run
+      end
+    rescue GemfileNotFound => error
+      invoke_other_command("cli_help")
+      raise error # re-raise to show the error and get a failing exit status
+    end
+
+    map aliases_for("install")
+
+    desc "update [OPTIONS]", "Update the current environment"
+    long_desc <<-D
+      Update will install the newest versions of the gems listed in the Gemfile. Use
+      update when you have changed the Gemfile, or if you want to get the newest
+      possible versions of the gems in the bundle.
+    D
+    method_option "full-index", type: :boolean, banner: "Fall back to using the single-file index of all gems"
+    method_option "gemfile", type: :string, banner: "Use the specified gemfile instead of Gemfile"
+    method_option "group", aliases: "-g", type: :array, banner: "Update a specific group"
+    method_option "jobs", aliases: "-j", type: :numeric, banner: "Specify the number of jobs to run in parallel"
+    method_option "local", type: :boolean, banner: "Do not attempt to fetch gems remotely and use the gem cache instead"
+    method_option "quiet", type: :boolean, banner: "Only output warnings and errors."
+    method_option "source", type: :array, banner: "Update a specific source (and all gems associated with it)"
+    method_option "force", type: :boolean, aliases: "--redownload", banner: "Force reinstalling every gem, even if already installed"
+    method_option "ruby", type: :boolean, banner: "Update ruby specified in Gemfile.lock"
+    method_option "bundler", type: :string, lazy_default: "> 0.a", banner: "Update the locked version of bundler"
+    method_option "patch", type: :boolean, banner: "Prefer updating only to next patch version"
+    method_option "minor", type: :boolean, banner: "Prefer updating only to next minor version"
+    method_option "major", type: :boolean, banner: "Prefer updating to next major version (default)"
+    method_option "pre", type: :boolean, banner: "Always choose the highest allowed version when updating gems, regardless of prerelease status"
+    method_option "strict", type: :boolean, banner: "Do not allow any gem to be updated past latest --patch | --minor | --major"
+    method_option "conservative", type: :boolean, banner: "Use bundle install conservative update behavior and do not allow shared dependencies to be updated."
+    method_option "all", type: :boolean, banner: "Update everything."
+    method_option "cooldown", type: :numeric, banner: "Only consider gem versions published at least N days ago. Use 0 to disable."
+    def update(*gems)
+      require_relative "cli/update"
+      Bundler.settings.temporary(no_install: false) do
+        Update.new(options, gems).run
+      end
+    end
+
+    desc "show GEM [OPTIONS]", "Shows all gems that are part of the bundle, or the path to a given gem"
+    long_desc <<-D
+      Show lists the names and versions of all gems that are required by your Gemfile.
+      Calling show with [GEM] will list the exact location of that gem on your machine.
+    D
+    method_option "paths", type: :boolean, banner: "List the paths of all gems that are required by your Gemfile."
+    method_option "outdated", type: :boolean, banner: "Show verbose output including whether gems are outdated (removed)."
+    def show(gem_name = nil)
+      if ARGV.include?("--outdated")
+        removed_message = "the `--outdated` flag to `bundle show` has been removed in favor of `bundle show --verbose`"
+        raise InvalidOption, removed_message
+      end
+      require_relative "cli/show"
+      Show.new(options, gem_name).run
+    end
+
+    desc "list", "List all gems in the bundle"
+    method_option "name-only", type: :boolean, banner: "print only the gem names"
+    method_option "only-group", type: :array, default: [], banner: "print gems from a given set of groups"
+    method_option "without-group", type: :array, default: [], banner: "print all gems except from a given set of groups"
+    method_option "format", type: :string, banner: "format output ('json' is the only supported format)"
+    method_option "paths", type: :boolean, banner: "print the path to each gem in the bundle"
+    def list
+      require_relative "cli/list"
+      List.new(options).run
+    end
+
+    map aliases_for("list")
+
+    desc "info GEM [OPTIONS]", "Show information for the given gem"
+    method_option "path", type: :boolean, banner: "Print full path to gem"
+    method_option "version", type: :boolean, banner: "Print gem version"
+    def info(gem_name)
+      require_relative "cli/info"
+      Info.new(options, gem_name).run
+    end
+
+    desc "binstubs GEM [OPTIONS]", "Install the binstubs of the listed gem"
+    long_desc <<-D
+      Generate binstubs for executables in [GEM]. Binstubs are put into bin,
+      or the --binstubs directory if one has been set. Calling binstubs with [GEM [GEM]]
+      will create binstubs for all given gems.
+    D
+    method_option "force", type: :boolean, default: false, banner: "Overwrite existing binstubs if they exist"
+    method_option "path", type: :string, lazy_default: "bin", banner: "Binstub destination directory, `bin` by default (removed)"
+    method_option "shebang", type: :string, banner: "Specify a different shebang executable name than the default (usually 'ruby')"
+    method_option "standalone", type: :boolean, banner: "Make binstubs that can work without the Bundler runtime"
+    method_option "all", type: :boolean, banner: "Install binstubs for all gems"
+    method_option "all-platforms", type: :boolean, default: false, banner: "Install binstubs for all platforms"
+    def binstubs(*gems)
+      remembered_flag_deprecation("path", option_name: "bin")
+
+      require_relative "cli/binstubs"
+      Binstubs.new(options, gems).run
+    end
+
+    desc "add GEM VERSION", "Add gem to Gemfile and run bundle install"
+    long_desc <<-D
+      Adds the specified gem to Gemfile (if valid) and run 'bundle install' in one step.
+    D
+    method_option "version", aliases: "-v", type: :string
+    method_option "group", aliases: "-g", type: :string
+    method_option "source", aliases: "-s", type: :string
+    method_option "require", aliases: "-r", type: :string, banner: "Adds require path to gem. Provide false, or a path as a string."
+    method_option "path", type: :string
+    method_option "git", type: :string
+    method_option "github", type: :string
+    method_option "branch", type: :string
+    method_option "ref", type: :string
+    method_option "glob", type: :string, banner: "The location of a dependency's .gemspec, expanded within Ruby (single quotes recommended)"
+    method_option "quiet", type: :boolean, banner: "Only output warnings and errors."
+    method_option "skip-install", type: :boolean, banner: "Adds gem to the Gemfile but does not install it"
+    method_option "optimistic", type: :boolean, banner: "Ignored (now default behavior)"
+    method_option "pessimistic", type: :boolean, banner: "Adds pessimistic declaration of version to gem"
+    method_option "strict", type: :boolean, banner: "Adds strict declaration of version to gem"
+    method_option "cooldown", type: :numeric, banner: "Only consider gem versions published at least N days ago. Use 0 to disable."
+    def add(*gems)
+      require_relative "cli/add"
+      Add.new(options.dup, gems).run
+    end
+
+    desc "outdated GEM [OPTIONS]", "List installed gems with newer versions available"
+    long_desc <<-D
+      Outdated lists the names and versions of gems that have a newer version available
+      in the given source. Calling outdated with [GEM [GEM]] will only check for newer
+      versions of the given gems. Prerelease gems are ignored by default. If your gems
+      are up to date, Bundler will exit with a status of 0. Otherwise, it will exit 1.
+
+      For more information on patch level options (--major, --minor, --patch,
+      --strict) see documentation on the same options on the update command.
+    D
+    method_option "group", type: :string, banner: "List gems from a specific group"
+    method_option "groups", type: :boolean, banner: "List gems organized by groups"
+    method_option "local", type: :boolean, banner: "Do not attempt to fetch gems remotely and use the gem cache instead"
+    method_option "pre", type: :boolean, banner: "Check for newer pre-release gems"
+    method_option "source", type: :array, banner: "Check against a specific source"
+    method_option "filter-strict", type: :boolean, aliases: "--strict", banner: "Only list newer versions allowed by your Gemfile requirements"
+    method_option "update-strict", type: :boolean, banner: "Strict conservative resolution, do not allow any gem to be updated past latest --patch | --minor | --major"
+    method_option "minor", type: :boolean, banner: "Prefer updating only to next minor version"
+    method_option "major", type: :boolean, banner: "Prefer updating to next major version (default)"
+    method_option "patch", type: :boolean, banner: "Prefer updating only to next patch version"
+    method_option "filter-major", type: :boolean, banner: "Only list major newer versions"
+    method_option "filter-minor", type: :boolean, banner: "Only list minor newer versions"
+    method_option "filter-patch", type: :boolean, banner: "Only list patch newer versions"
+    method_option "parseable", aliases: "--porcelain", type: :boolean, banner: "Use minimal formatting for more parseable output"
+    method_option "only-explicit", type: :boolean, banner: "Only list gems specified in your Gemfile, not their dependencies"
+    method_option "cooldown", type: :numeric, banner: "Only consider gem versions published at least N days ago. Use 0 to disable."
+    def outdated(*gems)
+      require_relative "cli/outdated"
+      Outdated.new(options, gems).run
+    end
+
+    desc "fund [OPTIONS]", "Lists information about gems seeking funding assistance"
+    method_option "group", aliases: "-g", type: :array, banner: "Fetch funding information for a specific group"
+    def fund
+      require_relative "cli/fund"
+      Fund.new(options).run
+    end
+
+    desc "cache [OPTIONS]", "Locks and then caches all of the gems into vendor/cache"
+    method_option "all", type: :boolean, default: Bundler.settings[:cache_all], banner: "Include all sources (including path and git) (removed)."
+    method_option "all-platforms", type: :boolean, banner: "Include gems for all platforms present in the lockfile, not only the current one"
+    method_option "cache-path", type: :string, banner: "Specify a different cache path than the default (vendor/cache)."
+    method_option "gemfile", type: :string, banner: "Use the specified gemfile instead of Gemfile"
+    method_option "no-install", type: :boolean, banner: "Don't install the gems, only update the cache."
+    method_option "no-prune", type: :boolean, banner: "Don't remove stale gems from the cache (removed)."
+    method_option "path", type: :string, banner: "Specify a different path than the system default, namely, $BUNDLE_PATH or $GEM_HOME (removed)."
+    method_option "quiet", type: :boolean, banner: "Only output warnings and errors."
+    method_option "frozen", type: :boolean, banner: "Do not allow the Gemfile.lock to be updated after this bundle cache operation's install (removed)"
+    long_desc <<-D
+      The cache command will copy the .gem files for every gem in the bundle into the
+      directory ./vendor/cache. If you then check that directory into your source
+      control repository, others who check out your source will be able to install the
+      bundle without having to download any additional gems.
+    D
+    def cache
+      print_remembered_flag_deprecation("--all", "cache_all", "true") if ARGV.include?("--all")
+      print_remembered_flag_deprecation("--no-all", "cache_all", "false") if ARGV.include?("--no-all")
+
+      %w[frozen no-prune].each do |option|
+        remembered_flag_deprecation(option)
+      end
+
+      if flag_passed?("--path")
+        removed_message =
+          "The `--path` flag has been removed because its semantics were unclear. " \
+          "Use `bundle config cache_path` to configure the path of your cache of gems, " \
+          "and `bundle config path` to configure the path where your gems are installed, " \
+          "and stop using this flag"
+        raise InvalidOption, removed_message
+      end
+
+      require_relative "cli/cache"
+      Cache.new(options).run
+    end
+
+    map aliases_for("cache")
+
+    desc "exec [OPTIONS]", "Run the command in context of the bundle"
+    method_option :keep_file_descriptors, type: :boolean, default: true, banner: "Passes all file descriptors to the new processes. Default is true, and setting it to false is not permitted (removed)."
+    method_option :gemfile, type: :string, required: false, banner: "Use the specified gemfile instead of Gemfile"
+    long_desc <<-D
+      Exec runs a command, providing it access to the gems in the bundle. While using
+      bundle exec you can require and call the bundled gems as if they were installed
+      into the system wide RubyGems repository.
+    D
+    def exec(*args)
+      if ARGV.include?("--no-keep-file-descriptors")
+        removed_message = "The `--no-keep-file-descriptors` has been removed. `bundle exec` no longer mess with your file descriptors. Close them in the exec'd script if you need to"
+        raise InvalidOption, removed_message
+      end
+
+      require_relative "cli/exec"
+      Exec.new(options, args).run
+    end
+
+    map aliases_for("exec")
+
+    desc "config NAME [VALUE]", "Retrieve or set a configuration value"
+    long_desc <<-D
+      Retrieves or sets a configuration value. If only one parameter is provided, retrieve the value. If two parameters are provided, replace the
+      existing value with the newly provided one.
+
+      By default, setting a configuration value sets it for all projects
+      on the machine.
+
+      If a global setting is superseded by local configuration, this command
+      will show the current value, as well as any superseded values and
+      where they were specified.
+    D
+    require_relative "cli/config"
+    subcommand "config", Config
+
+    desc "open GEM", "Opens the source directory of the given bundled gem"
+    method_option "path", type: :string, lazy_default: "", banner: "Open relative path of the gem source."
+    def open(name)
+      require_relative "cli/open"
+      Open.new(options, name).run
+    end
+
+    desc "console [GROUP]", "Opens an IRB session with the bundle pre-loaded"
+    def console(group = nil)
+      require_relative "cli/console"
+      Console.new(options, group).run
+    end
+
+    desc "version", "Prints Bundler version information"
+    def version
+      cli_help = current_command.name == "cli_help"
+      if cli_help || ARGV.include?("version")
+        build_info = " (#{BuildMetadata.timestamp} commit #{BuildMetadata.git_commit_sha})"
+      end
+
+      if !cli_help
+        Bundler.ui.info "#{Bundler.verbose_version}#{build_info}"
+      else
+        Bundler.ui.info "Bundler version #{Bundler.verbose_version}#{build_info}"
+      end
+    end
+
+    map aliases_for("version")
+
+    desc "licenses", "Prints the license of all gems in the bundle"
+    def licenses
+      Bundler.load.specs.sort_by {|s| s.license.to_s }.reverse_each do |s|
+        gem_name = s.name
+        license  = s.license || s.licenses
+
+        if license.empty?
+          Bundler.ui.warn "#{gem_name}: Unknown"
+        else
+          Bundler.ui.info "#{gem_name}: #{license}"
+        end
+      end
+    end
+
+    desc "viz [OPTIONS]", "Generates a visual dependency graph", hide: true
+    def viz
+      SharedHelpers.feature_removed! "The `viz` command has been renamed to `graph` and moved to a plugin. See https://github.com/rubygems/bundler-graph"
+    end
+
+    desc "gem NAME [OPTIONS]", "Creates a skeleton for creating a rubygem"
+    method_option :exe, type: :boolean, default: false, aliases: ["--bin", "-b"], banner: "Generate a binary executable for your library."
+    method_option :coc, type: :boolean, banner: "Generate a code of conduct file. Set a default with `bundle config set --global gem.coc true`."
+    method_option :edit, type: :string, aliases: "-e", required: false, lazy_default: [ENV["BUNDLER_EDITOR"], ENV["VISUAL"], ENV["EDITOR"]].find {|e| !e.nil? && !e.empty? }, banner: "Open generated gemspec in the specified editor (defaults to $EDITOR or $BUNDLER_EDITOR)"
+    method_option :ext, type: :string, banner: "Generate the boilerplate for C extension code.", enum: EXTENSIONS
+    method_option :git, type: :boolean, default: true, banner: "Initialize a git repo inside your library."
+    method_option :mit, type: :boolean, banner: "Generate an MIT license file. Set a default with `bundle config set --global gem.mit true`."
+    method_option :rubocop, type: :boolean, banner: "Add rubocop to the generated Rakefile and gemspec. Set a default with `bundle config set --global gem.rubocop true` (removed)."
+    method_option :changelog, type: :boolean, banner: "Generate changelog file. Set a default with `bundle config set --global gem.changelog true`."
+    method_option :test, type: :string, lazy_default: Bundler.settings["gem.test"] || "", aliases: "-t", banner: "Use the specified test framework for your library", enum: %w[rspec minitest test-unit], desc: "Generate a test directory for your library, either rspec, minitest or test-unit. Set a default with `bundle config set --global gem.test (rspec|minitest|test-unit)`."
+    method_option :ci, type: :string, lazy_default: Bundler.settings["gem.ci"] || "", enum: %w[github gitlab circle], banner: "Generate CI configuration, either GitHub Actions, GitLab CI or CircleCI. Set a default with `bundle config set --global gem.ci (github|gitlab|circle)`"
+    method_option :linter, type: :string, lazy_default: Bundler.settings["gem.linter"] || "", enum: %w[rubocop standard], banner: "Add a linter and code formatter, either RuboCop or Standard. Set a default with `bundle config set --global gem.linter (rubocop|standard)`"
+    method_option :github_username, type: :string, default: Bundler.settings["gem.github_username"], banner: "Set your username on GitHub", desc: "Fill in GitHub username on README so that you don't have to do it manually. Set a default with `bundle config set --global gem.github_username <your_username>`."
+    method_option :bundle, type: :boolean, default: Bundler.settings["gem.bundle"], banner: "Automatically run `bundle install` after creation. Set a default with `bundle config set --global gem.bundle true`"
+
+    def gem(name)
+      require_relative "cli/gem"
+
+      raise InvalidOption, "--rubocop has been removed, use --linter=rubocop" if ARGV.include?("--rubocop")
+      raise InvalidOption, "--no-rubocop has been removed, use --no-linter" if ARGV.include?("--no-rubocop")
+
+      cmd_args = args + [self]
+      cmd_args.unshift(options)
+
+      Gem.new(*cmd_args).run
+    end
+
+    def self.source_root
+      File.expand_path("templates", __dir__)
+    end
+
+    desc "clean [OPTIONS]", "Cleans up unused gems in your bundler directory"
+    method_option "dry-run", type: :boolean, default: false, banner: "Only print out changes, do not clean gems"
+    method_option "force", type: :boolean, default: false, banner: "Forces cleaning up unused gems even if Bundler is configured to use globally installed gems. As a consequence, removes all system gems except for the ones in the current application."
+    def clean
+      require_relative "cli/clean"
+      Clean.new(options.dup).run
+    end
+
+    desc "platform [OPTIONS]", "Displays platform compatibility information"
+    method_option "ruby", type: :boolean, default: false, banner: "only display ruby related platform information"
+    def platform
+      require_relative "cli/platform"
+      Platform.new(options).run
+    end
+
+    desc "inject GEM VERSION", "Add the named gem, with version requirements, to the resolved Gemfile", hide: true
+    def inject(*)
+      SharedHelpers.feature_removed! "The `inject` command has been replaced by the `add` command"
+    end
+
+    desc "lock", "Creates a lockfile without installing"
+    method_option "update", type: :array, lazy_default: true, banner: "ignore the existing lockfile, update all gems by default, or update list of given gems"
+    method_option "local", type: :boolean, default: false, banner: "do not attempt to fetch remote gemspecs and use the local gem cache only"
+    method_option "print", type: :boolean, default: false, banner: "print the lockfile to STDOUT instead of writing to the file system"
+    method_option "gemfile", type: :string, banner: "Use the specified gemfile instead of Gemfile"
+    method_option "lockfile", type: :string, default: nil, banner: "the path the lockfile should be written to"
+    method_option "full-index", type: :boolean, default: false, banner: "Fall back to using the single-file index of all gems"
+    method_option "add-checksums", type: :boolean, default: false, banner: "Adds checksums to the lockfile"
+    method_option "add-platform", type: :array, default: [], banner: "Add a new platform to the lockfile"
+    method_option "remove-platform", type: :array, default: [], banner: "Remove a platform from the lockfile"
+    method_option "normalize-platforms", type: :boolean, default: false, banner: "Normalize lockfile platforms"
+    method_option "patch", type: :boolean, banner: "If updating, prefer updating only to next patch version"
+    method_option "minor", type: :boolean, banner: "If updating, prefer updating only to next minor version"
+    method_option "major", type: :boolean, banner: "If updating, prefer updating to next major version (default)"
+    method_option "pre", type: :boolean, banner: "If updating, always choose the highest allowed version, regardless of prerelease status"
+    method_option "strict", type: :boolean, banner: "If updating, do not allow any gem to be updated past latest --patch | --minor | --major"
+    method_option "conservative", type: :boolean, banner: "If updating, use bundle install conservative update behavior and do not allow shared dependencies to be updated"
+    method_option "bundler", type: :string, lazy_default: "> 0.a", banner: "Update the locked version of bundler"
+    def lock
+      require_relative "cli/lock"
+      Lock.new(options).run
+    end
+
+    desc "env", "Print information about the environment Bundler is running under"
+    def env
+      Env.write($stdout)
+    end
+
+    desc "doctor [OPTIONS]", "Checks the bundle for common problems"
+    require_relative "cli/doctor"
+    subcommand("doctor", Doctor)
+
+    desc "issue", "Learn how to report an issue in Bundler"
+    def issue
+      require_relative "cli/issue"
+      Issue.new.run
+    end
+
+    desc "pristine [GEMS...]", "Restores installed gems to pristine condition"
+    long_desc <<-D
+      Restores installed gems to pristine condition from files located in the
+      gem cache. Gems installed from a git repository will be issued `git
+      checkout --force`.
+    D
+    def pristine(*gems)
+      require_relative "cli/pristine"
+      Bundler.settings.temporary(no_install: false) do
+        Pristine.new(gems).run
+      end
+    end
+
+    if Bundler.settings[:plugins]
+      require_relative "cli/plugin"
+      desc "plugin", "Manage the bundler plugins"
+      subcommand "plugin", Plugin
+    end
+
+    # Reformat the arguments passed to bundle that include a --help flag
+    # into the corresponding `bundle help #{command}` call
+    def self.reformatted_help_args(args)
+      bundler_commands = (COMMAND_ALIASES.keys + COMMAND_ALIASES.values).flatten
+
+      help_flags = %w[--help -h]
+      exec_commands = ["exec"] + COMMAND_ALIASES["exec"]
+
+      help_used = args.index {|a| help_flags.include? a }
+      exec_used = args.index {|a| exec_commands.include? a }
+
+      command = args.find {|a| bundler_commands.include? a }
+
+      if exec_used && help_used
+        if exec_used + help_used == 1
+          %w[help exec]
+        else
+          args
+        end
+      elsif help_used
+        args = args.dup
+        args.delete_at(help_used)
+        ["help", command || args].flatten.compact
+      else
+        args
+      end
+    end
+
+    def self.check_invalid_ext_option(arguments)
+      # when invalid version of `--ext` is called
+      if invalid_ext_value?(arguments)
+        removed_message = "Extensions can now be generated using C or Rust, so `--ext` with no arguments has been removed. Please select a language, e.g. `--ext=rust` to generate a Rust extension."
+        raise InvalidOption, removed_message
+      end
+    end
+
+    def self.invalid_ext_value?(arguments)
+      index = arguments.index("--ext")
+      next_argument = arguments[index + 1]
+
+      # it is ok when --ext is followed with valid extension value
+      # for example `bundle gem hello --ext c`
+      return false if EXTENSIONS.include?(next_argument)
+
+      # invalid call when --ext is called with no value in last position
+      # for example `bundle gem hello_gem --ext`
+      return true if next_argument.nil?
+
+      # invalid call when --ext is followed by other parameter
+      # for example `bundle gem --ext --no-ci hello_gem`
+      return true if next_argument.start_with?("-")
+
+      # invalid call when --ext is followed by gem name
+      # for example `bundle gem --ext hello_gem`
+      return true if next_argument
+
+      false
+    end
+
+    private
+
+    def current_command
+      _, _, config = @_initializer
+      config[:current_command]
+    end
+
+    def invoke_other_command(name)
+      _, _, config = @_initializer
+      original_command = config[:current_command]
+      command = self.class.all_commands[name]
+      config[:current_command] = command
+      send(name)
+    ensure
+      config[:current_command] = original_command
+    end
+
+    def current_command=(command)
+    end
+
+    def print_command
+      return unless Bundler.ui.debug?
+      cmd = current_command
+      command_name = cmd.name
+      return if PARSEABLE_COMMANDS.include?(command_name)
+      command = ["bundle", command_name] + args
+      options_to_print = options.dup
+      options_to_print.delete_if do |k, v|
+        next unless o = cmd.options[k]
+        o.default == v
+      end
+      command << Thor::Options.to_switches(options_to_print.sort_by(&:first)).strip
+      command.reject!(&:empty?)
+      Bundler.ui.info "Running `#{command * " "}` with bundler #{Bundler.verbose_version}"
+    end
+
+    def warn_on_outdated_bundler
+      return if Bundler.settings[:disable_version_check]
+
+      command_name = current_command.name
+      return if PARSEABLE_COMMANDS.include?(command_name)
+
+      return unless SharedHelpers.md5_available?
+
+      require_relative "vendored_uri"
+      remote = Source::Rubygems::Remote.new(Gem::URI("https://rubygems.org"))
+      cache_path = Bundler.user_cache.join("compact_index", remote.cache_slug)
+      latest = Bundler::CompactIndexClient.new(cache_path).latest_version("bundler")
+      return unless latest
+
+      current = Gem::Version.new(VERSION)
+      return if current >= latest
+
+      Bundler.ui.warn \
+        "The latest bundler is #{latest}, but you are currently running #{current}.\n" \
+        "To update to the most recent version, run `bundle update --bundler`"
+    rescue RuntimeError
+      nil
+    end
+
+    def remembered_flag_deprecation(name, negative: false, option_name: nil)
+      option = current_command.options[name]
+      flag_name = option.switch_name
+      flag_name = "--no-" + flag_name.gsub(/\A--/, "") if negative
+      return unless flag_passed?(flag_name)
+
+      value = options[name]
+      value = value.join(" ").to_s if option.type == :array
+      value = "'#{value}'" unless option.type == :boolean
+
+      print_remembered_flag_deprecation(flag_name, option_name || name.tr("-", "_"), value)
+    end
+
+    def print_remembered_flag_deprecation(flag_name, option_name, option_value)
+      removed_message =
+        "The `#{flag_name}` flag has been removed because it relied on being " \
+        "remembered across bundler invocations, which bundler no longer does. " \
+        "Instead please use `bundle config set #{option_name} #{option_value}`, " \
+        "and stop using this flag"
+      raise InvalidOption, removed_message
+    end
+
+    def flag_passed?(name)
+      ARGV.any? {|arg| name == arg.split("=")[0] }
+    end
+  end
+end
diff --git a/lib/bundler/cli/add.rb b/lib/bundler/cli/add.rb
new file mode 100644
index 0000000000..20f76b59d1
--- /dev/null
+++ b/lib/bundler/cli/add.rb
@@ -0,0 +1,62 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Add
+    attr_reader :gems, :options, :version
+
+    def initialize(options, gems)
+      @gems = gems
+      @options = options
+      @options[:group] = options[:group].split(",").map(&:strip) unless options[:group].nil?
+      @version = options[:version].split(",").map(&:strip) unless options[:version].nil?
+    end
+
+    def run
+      Bundler.ui.level = "warn" if options[:quiet]
+
+      Bundler::CLI::Common.validate_cooldown!(options[:cooldown])
+      Bundler.settings.set_command_option_if_given :cooldown, options[:cooldown]
+
+      validate_options!
+      inject_dependencies
+      perform_bundle_install unless options["skip-install"]
+    end
+
+    private
+
+    def perform_bundle_install
+      Installer.install(Bundler.root, Bundler.definition)
+      Bundler.load.cache if Bundler.app_cache.exist?
+    end
+
+    def inject_dependencies
+      dependencies = gems.map {|g| Bundler::Dependency.new(g, version, options) }
+
+      Injector.inject(dependencies,
+        conservative_versioning: options[:version].nil?, # Perform conservative versioning only when version is not specified
+        pessimistic: options[:pessimistic],
+        strict: options[:strict])
+    end
+
+    def validate_options!
+      raise InvalidOption, "You cannot specify `--git` and `--github` at the same time." if options["git"] && options["github"]
+
+      unless options["git"] || options["github"]
+        raise InvalidOption, "You cannot specify `--branch` unless `--git` or `--github` is specified." if options["branch"]
+
+        raise InvalidOption, "You cannot specify `--ref` unless `--git` or `--github` is specified." if options["ref"]
+      end
+
+      raise InvalidOption, "You cannot specify `--branch` and `--ref` at the same time." if options["branch"] && options["ref"]
+
+      raise InvalidOption, "You cannot specify `--strict` and `--pessimistic` at the same time." if options[:strict] && options[:pessimistic]
+
+      # raise error when no gems are specified
+      raise InvalidOption, "Please specify gems to add." if gems.empty?
+
+      version.to_a.each do |v|
+        raise InvalidOption, "Invalid gem requirement pattern '#{v}'" unless Gem::Requirement::PATTERN.match?(v.to_s)
+      end
+    end
+  end
+end
diff --git a/lib/bundler/cli/binstubs.rb b/lib/bundler/cli/binstubs.rb
new file mode 100644
index 0000000000..8ce138df96
--- /dev/null
+++ b/lib/bundler/cli/binstubs.rb
@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Binstubs
+    attr_reader :options, :gems
+    def initialize(options, gems)
+      @options = options
+      @gems = gems
+    end
+
+    def run
+      Bundler.definition.validate_runtime!
+      path_option = options["path"]
+      path_option = nil if path_option&.empty?
+      Bundler.settings.set_command_option :bin, path_option if options["path"]
+      Bundler.settings.set_command_option_if_given :shebang, options["shebang"]
+      installer = Installer.new(Bundler.root, Bundler.definition)
+
+      installer_opts = {
+        force: options[:force],
+        binstubs_cmd: true,
+        all_platforms: options["all-platforms"],
+      }
+
+      if options[:all]
+        raise InvalidOption, "Cannot specify --all with specific gems" unless gems.empty?
+        @gems = Bundler.definition.specs.map(&:name)
+        installer_opts.delete(:binstubs_cmd)
+      elsif gems.empty?
+        Bundler.ui.error "`bundle binstubs` needs at least one gem to run."
+        exit 1
+      end
+
+      gems.each do |gem_name|
+        spec = Bundler.definition.specs.find {|s| s.name == gem_name }
+        unless spec
+          raise GemNotFound, Bundler::CLI::Common.gem_not_found_message(
+            gem_name, Bundler.definition.specs
+          )
+        end
+
+        if options[:standalone]
+          if gem_name == "bundler"
+            Bundler.ui.warn("Sorry, Bundler can only be run via RubyGems.") unless options[:all]
+            next
+          end
+
+          Bundler.settings.temporary(path: Bundler.settings[:path] || Bundler.root) do
+            installer.generate_standalone_bundler_executable_stubs(spec, installer_opts)
+          end
+        else
+          installer.generate_bundler_executable_stubs(spec, installer_opts)
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/cli/cache.rb b/lib/bundler/cli/cache.rb
new file mode 100644
index 0000000000..59605df847
--- /dev/null
+++ b/lib/bundler/cli/cache.rb
@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Cache
+    attr_reader :options
+
+    def initialize(options)
+      @options = options
+    end
+
+    def run
+      Bundler.ui.level = "warn" if options[:quiet]
+      Bundler.settings.set_command_option_if_given :cache_path, options["cache-path"]
+
+      install
+
+      Bundler.settings.temporary(cache_all_platforms: options["all-platforms"]) do
+        Bundler.load.cache
+      end
+    end
+
+    private
+
+    def install
+      require_relative "install"
+      options = self.options.dup
+      options["local"] = false if Bundler.settings[:cache_all_platforms]
+      options["no-cache"] = true
+      Bundler::CLI::Install.new(options).run
+    end
+  end
+end
diff --git a/lib/bundler/cli/check.rb b/lib/bundler/cli/check.rb
new file mode 100644
index 0000000000..493eb3ec6a
--- /dev/null
+++ b/lib/bundler/cli/check.rb
@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Check
+    attr_reader :options
+
+    def initialize(options)
+      @options = options
+    end
+
+    def run
+      Bundler.settings.set_command_option_if_given :path, options[:path]
+
+      definition = Bundler.definition
+      definition.validate_runtime!
+
+      begin
+        definition.check!
+        not_installed = definition.missing_specs
+      rescue GemNotFound, GitError, SolveFailure
+        Bundler.ui.error "Bundler can't satisfy your Gemfile's dependencies."
+        Bundler.ui.warn "Install missing gems with `bundle install`."
+        exit 1
+      end
+
+      if not_installed.any?
+        Bundler.ui.error "The following gems are missing"
+        not_installed.each {|s| Bundler.ui.error " * #{s.name} (#{s.version})" }
+        Bundler.ui.warn "Install missing gems with `bundle install`"
+        exit 1
+      elsif !Bundler.default_lockfile.file? && Bundler.frozen_bundle?
+        Bundler.ui.error "This bundle has been frozen, but there is no #{SharedHelpers.relative_lockfile_path} present"
+        exit 1
+      else
+        definition.lock(true) unless options[:"dry-run"]
+        Bundler.ui.info "The Gemfile's dependencies are satisfied"
+      end
+    end
+  end
+end
diff --git a/lib/bundler/cli/clean.rb b/lib/bundler/cli/clean.rb
new file mode 100644
index 0000000000..c6b0968e3e
--- /dev/null
+++ b/lib/bundler/cli/clean.rb
@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Clean
+    attr_reader :options
+
+    def initialize(options)
+      @options = options
+    end
+
+    def run
+      require_path_or_force unless options[:"dry-run"]
+      Bundler.load.clean(options[:"dry-run"])
+    end
+
+    protected
+
+    def require_path_or_force
+      return unless Bundler.use_system_gems? && !options[:force]
+      raise InvalidOption, "Cleaning all the gems on your system is dangerous! " \
+        "If you're sure you want to remove every system gem not in this " \
+        "bundle, run `bundle clean --force`."
+    end
+  end
+end
diff --git a/lib/bundler/cli/common.rb b/lib/bundler/cli/common.rb
new file mode 100644
index 0000000000..b44fbc3096
--- /dev/null
+++ b/lib/bundler/cli/common.rb
@@ -0,0 +1,161 @@
+# frozen_string_literal: true
+
+module Bundler
+  module CLI::Common
+    def self.validate_cooldown!(value)
+      return if value.nil?
+      return if value.is_a?(Integer) && value >= 0
+      raise InvalidOption, "Expected `--cooldown` to be a non-negative integer, got #{value.inspect}"
+    end
+
+    def self.output_post_install_messages(messages)
+      return if Bundler.settings["ignore_messages"]
+      messages.to_a.each do |name, msg|
+        print_post_install_message(name, msg) unless Bundler.settings["ignore_messages.#{name}"]
+      end
+    end
+
+    def self.print_post_install_message(name, msg)
+      Bundler.ui.confirm "Post-install message from #{name}:"
+      Bundler.ui.info msg
+    end
+
+    def self.output_fund_metadata_summary
+      return if Bundler.settings["ignore_funding_requests"]
+      definition = Bundler.definition
+      current_dependencies = definition.requested_dependencies
+      current_specs = definition.specs
+
+      count = current_dependencies.count {|dep| current_specs[dep.name].first.metadata.key?("funding_uri") }
+
+      return if count.zero?
+
+      intro = count > 1 ? "#{count} installed gems you directly depend on are" : "#{count} installed gem you directly depend on is"
+      message = "#{intro} looking for funding.\n  Run `bundle fund` for details"
+      Bundler.ui.info message
+    end
+
+    def self.output_without_groups_message(command)
+      return if Bundler.settings[:without].empty?
+      Bundler.ui.confirm without_groups_message(command)
+    end
+
+    def self.without_groups_message(command)
+      command_in_past_tense = command == :install ? "installed" : "updated"
+      groups = Bundler.settings[:without]
+      "Gems in the #{verbalize_groups(groups)} were not #{command_in_past_tense}."
+    end
+
+    def self.verbalize_groups(groups)
+      groups.map! {|g| "'#{g}'" }
+      group_list = [groups[0...-1].join(", "), groups[-1..-1]].
+        reject {|s| s.to_s.empty? }.join(" and ")
+      group_str = groups.size == 1 ? "group" : "groups"
+      "#{group_str} #{group_list}"
+    end
+
+    def self.select_spec(name, regex_match = nil)
+      specs = []
+      regexp = Regexp.new(name) if regex_match
+
+      Bundler.definition.specs.each do |spec|
+        return spec if spec.name == name
+        specs << spec if regexp && spec.name.match?(regexp)
+      end
+
+      default_spec = default_gem_spec(name)
+      specs << default_spec if default_spec
+
+      case specs.count
+      when 0
+        dep_in_other_group = Bundler.definition.current_dependencies.find {|dep|dep.name == name }
+
+        if dep_in_other_group
+          raise GemNotFound, "Could not find gem '#{name}', because it's in the #{verbalize_groups(dep_in_other_group.groups)}, configured to be ignored."
+        else
+          raise GemNotFound, gem_not_found_message(name, Bundler.definition.dependencies)
+        end
+      when 1
+        specs.first
+      else
+        ask_for_spec_from(specs)
+      end
+    rescue RegexpError
+      raise GemNotFound, gem_not_found_message(name, Bundler.definition.dependencies)
+    end
+
+    def self.default_gem_spec(name)
+      gem_spec = Gem::Specification.find_all_by_name(name).last
+      gem_spec if gem_spec&.default_gem?
+    end
+
+    def self.ask_for_spec_from(specs)
+      specs.each_with_index do |spec, index|
+        Bundler.ui.info "#{index.succ} : #{spec.name}", true
+      end
+      Bundler.ui.info "0 : - exit -", true
+
+      num = Bundler.ui.ask("> ").to_i
+      num > 0 ? specs[num - 1] : nil
+    end
+
+    def self.gem_not_found_message(missing_gem_name, alternatives)
+      message = "Could not find gem '#{missing_gem_name}'."
+      alternate_names = alternatives.map {|a| a.respond_to?(:name) ? a.name : a }
+      if alternate_names.include?(missing_gem_name.downcase)
+        message += "\nDid you mean '#{missing_gem_name.downcase}'?"
+      elsif defined?(DidYouMean::SpellChecker)
+        suggestions = DidYouMean::SpellChecker.new(dictionary: alternate_names).correct(missing_gem_name)
+        message += "\nDid you mean #{word_list(suggestions)}?" unless suggestions.empty?
+      end
+      message
+    end
+
+    def self.ensure_all_gems_in_lockfile!(names, locked_gems = Bundler.locked_gems)
+      return unless locked_gems
+
+      locked_names = locked_gems.specs.map(&:name).uniq
+      names.-(locked_names).each do |g|
+        raise GemNotFound, gem_not_found_message(g, locked_names)
+      end
+    end
+
+    def self.configure_gem_version_promoter(definition, options)
+      patch_level = patch_level_options(options)
+      patch_level << :patch if patch_level.empty? && Bundler.settings[:prefer_patch]
+      raise InvalidOption, "Provide only one of the following options: #{patch_level.join(", ")}" unless patch_level.length <= 1
+
+      definition.gem_version_promoter.tap do |gvp|
+        gvp.level = patch_level.first || :major
+        gvp.strict = options[:strict] || options["filter-strict"]
+        gvp.pre = options[:pre]
+      end
+    end
+
+    def self.patch_level_options(options)
+      [:major, :minor, :patch].select {|v| options.keys.include?(v.to_s) }
+    end
+
+    def self.clean_after_install?
+      clean = Bundler.settings[:clean]
+      return clean unless clean.nil?
+      clean ||= Bundler.feature_flag.bundler_5_mode? && Bundler.settings[:path].nil?
+      clean &&= !Bundler.use_system_gems?
+      clean
+    end
+
+    def self.word_list(words)
+      if words.empty?
+        return ""
+      end
+
+      words = words.map {|word| "'#{word}'" }
+
+      if words.length == 1
+        return words[0]
+      end
+
+      [words[0..-2].join(", "), words[-1]].join(" or ")
+    end
+  end
+end
diff --git a/lib/bundler/cli/config.rb b/lib/bundler/cli/config.rb
new file mode 100644
index 0000000000..976cda7484
--- /dev/null
+++ b/lib/bundler/cli/config.rb
@@ -0,0 +1,208 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Config < Thor
+    class_option :parseable, type: :boolean, banner: "Use minimal formatting for more parseable output"
+
+    def self.scope_options
+      method_option :global, type: :boolean, banner: "Only change the global config"
+      method_option :local, type: :boolean, banner: "Only change the local config"
+    end
+    private_class_method :scope_options
+
+    desc "base NAME [VALUE]", "The Bundler 1 config interface", hide: true
+    scope_options
+    method_option :delete, type: :boolean, banner: "delete"
+    def base(name = nil, *value)
+      new_args =
+        if ARGV.size == 1
+          ["config", "list"]
+        elsif ARGV.include?("--delete")
+          ARGV.map {|arg| arg == "--delete" ? "unset" : arg }
+        elsif ARGV.include?("--global") || ARGV.include?("--local") || ARGV.size == 3
+          ["config", "set", *ARGV[1..-1]]
+        else
+          ["config", "get", ARGV[1]]
+        end
+
+      message = "Using the `config` command without a subcommand [list, get, set, unset] is deprecated and will be removed in the future. Use `bundle #{new_args.join(" ")}` instead."
+      SharedHelpers.feature_deprecated! message
+
+      Base.new(options, name, value, self).run
+    end
+
+    desc "list", "List out all configured settings"
+    def list
+      Base.new(options, nil, nil, self).run
+    end
+
+    desc "get NAME", "Returns the value for the given key"
+    def get(name)
+      Base.new(options, name, nil, self).run
+    end
+
+    desc "set NAME VALUE", "Sets the given value for the given key"
+    scope_options
+    def set(name, value, *value_)
+      Base.new(options, name, value_.unshift(value), self).run
+    end
+
+    desc "unset NAME", "Unsets the value for the given key"
+    scope_options
+    def unset(name)
+      options[:delete] = true
+      Base.new(options, name, nil, self).run
+    end
+
+    default_task :base
+
+    class Base
+      attr_reader :name, :value, :options, :scope, :thor
+
+      def initialize(options, name, value, thor)
+        @options = options
+        @name = name
+        value = Array(value)
+        @value = value.empty? ? nil : value.join(" ")
+        @thor = thor
+        validate_scope!
+      end
+
+      def run
+        unless name
+          warn_unused_scope "Ignoring --#{scope}"
+          confirm_all
+          return
+        end
+
+        if options[:delete]
+          if !explicit_scope? || scope != "global"
+            Bundler.settings.set_local(name, nil)
+          end
+          if !explicit_scope? || scope != "local"
+            Bundler.settings.set_global(name, nil)
+          end
+          return
+        end
+
+        if value.nil?
+          warn_unused_scope "Ignoring --#{scope} since no value to set was given"
+          current_value = Bundler.settings[name]
+
+          if options[:parseable]
+            if value = Bundler.settings[name]
+              Bundler.ui.info("#{name}=#{value}")
+            end
+          else
+            confirm(name)
+          end
+
+          if current_value.nil?
+            exit 1
+          else
+            return
+          end
+        end
+
+        Bundler.ui.info(message) if message
+        Bundler.settings.send("set_#{scope}", name, new_value)
+      end
+
+      def confirm_all
+        if @options[:parseable]
+          thor.with_padding do
+            Bundler.settings.all.each do |setting|
+              val = Bundler.settings[setting]
+              Bundler.ui.info "#{setting}=#{val}"
+            end
+          end
+        else
+          Bundler.ui.confirm "Settings are listed in order of priority. The top value will be used.\n"
+          Bundler.settings.all.each do |setting|
+            Bundler.ui.confirm setting
+            show_pretty_values_for(setting)
+            Bundler.ui.confirm ""
+          end
+        end
+      end
+
+      def confirm(name)
+        Bundler.ui.confirm "Settings for `#{name}` in order of priority. The top value will be used"
+        show_pretty_values_for(name)
+      end
+
+      def new_value
+        pathname = Pathname.new(value)
+        if name.start_with?("local.") && pathname.directory?
+          pathname.expand_path.to_s
+        else
+          value
+        end
+      end
+
+      def message
+        locations = Bundler.settings.locations(name)
+        if @options[:parseable]
+          "#{name}=#{new_value}" if new_value
+        elsif scope == "global"
+          if !locations[:local].nil?
+            "Your application has set #{name} to #{locations[:local].inspect}. " \
+              "This will override the global value you are currently setting"
+          elsif locations[:env]
+            "You have a bundler environment variable for #{name} set to " \
+              "#{locations[:env].inspect}. This will take precedence over the global value you are setting"
+          elsif !locations[:global].nil? && locations[:global] != value
+            "You are replacing the current global value of #{name}, which is currently " \
+              "#{locations[:global].inspect}"
+          end
+        elsif scope == "local" && !locations[:local].nil? && locations[:local] != value
+          "You are replacing the current local value of #{name}, which is currently " \
+            "#{locations[:local].inspect}"
+        end
+      end
+
+      def show_pretty_values_for(setting)
+        thor.with_padding do
+          Bundler.settings.pretty_values_for(setting).each do |line|
+            Bundler.ui.info line
+          end
+        end
+      end
+
+      def explicit_scope?
+        @explicit_scope
+      end
+
+      def warn_unused_scope(msg)
+        return unless explicit_scope?
+        return if options[:parseable]
+
+        Bundler.ui.warn(msg)
+      end
+
+      def validate_scope!
+        @explicit_scope = true
+        scopes = %w[global local].select {|s| options[s] }
+        case scopes.size
+        when 0
+          @scope = inside_app? ? "local" : "global"
+          @explicit_scope = false
+        when 1
+          @scope = scopes.first
+        else
+          raise InvalidOption,
+            "The options #{scopes.join " and "} were specified. Please only use one of the switches at a time."
+        end
+      end
+
+      private
+
+      def inside_app?
+        Bundler.root
+        true
+      rescue GemfileNotFound
+        false
+      end
+    end
+  end
+end
diff --git a/lib/bundler/cli/console.rb b/lib/bundler/cli/console.rb
new file mode 100644
index 0000000000..2d1a2ce458
--- /dev/null
+++ b/lib/bundler/cli/console.rb
@@ -0,0 +1,47 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Console
+    attr_reader :options, :group
+    def initialize(options, group)
+      @options = options
+      @group = group
+    end
+
+    def run
+      group ? Bundler.require(:default, *group.split(" ").map!(&:to_sym)) : Bundler.require
+      ARGV.clear
+
+      console = get_console(Bundler.settings[:console] || "irb")
+      console.start
+    end
+
+    def get_console(name)
+      require name
+      get_constant(name)
+    rescue LoadError
+      if name == "irb"
+        if defined?(Gem::BUNDLED_GEMS) && Gem::BUNDLED_GEMS.respond_to?(:force_activate)
+          Gem::BUNDLED_GEMS.force_activate "irb"
+          require name
+          return get_constant(name)
+        end
+        Bundler.ui.error "#{name} is not available"
+        exit 1
+      else
+        Bundler.ui.error "Couldn't load console #{name}, falling back to irb"
+        name = "irb"
+        retry
+      end
+    end
+
+    def get_constant(name)
+      const_name = {
+        "pry" => :Pry,
+        "ripl" => :Ripl,
+        "irb" => :IRB,
+      }[name]
+      Object.const_get(const_name)
+    end
+  end
+end
diff --git a/lib/bundler/cli/doctor.rb b/lib/bundler/cli/doctor.rb
new file mode 100644
index 0000000000..5fd6a73d91
--- /dev/null
+++ b/lib/bundler/cli/doctor.rb
@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Doctor < Thor
+    default_command(:diagnose)
+
+    desc "diagnose [OPTIONS]", "Checks the bundle for common problems"
+    long_desc <<-D
+      Doctor scans the OS dependencies of each of the gems requested in the Gemfile. If
+      missing dependencies are detected, Bundler prints them and exits status 1.
+      Otherwise, Bundler prints a success message and exits with a status of 0.
+    D
+    method_option "gemfile", type: :string, banner: "Use the specified gemfile instead of Gemfile"
+    method_option "quiet", type: :boolean, banner: "Only output warnings and errors."
+    method_option "ssl", type: :boolean, default: false, banner: "Diagnose SSL problems."
+    def diagnose
+      require_relative "doctor/diagnose"
+      Diagnose.new(options).run
+    end
+
+    desc "ssl [OPTIONS]", "Diagnose SSL problems"
+    long_desc <<-D
+      Diagnose SSL problems, especially related to certificates or TLS version while connecting to https://rubygems.org.
+    D
+    method_option "host", type: :string, banner: "The host to diagnose."
+    method_option "tls-version", type: :string, banner: "Specify the SSL/TLS version when running the diagnostic. Accepts either <1.1> or <1.2>"
+    method_option "verify-mode", type: :string, banner: "Specify the mode used for certification verification. Accepts either <peer> or <none>"
+    def ssl
+      require_relative "doctor/ssl"
+      SSL.new(options).run
+    end
+  end
+end
diff --git a/lib/bundler/cli/doctor/diagnose.rb b/lib/bundler/cli/doctor/diagnose.rb
new file mode 100644
index 0000000000..a878025dda
--- /dev/null
+++ b/lib/bundler/cli/doctor/diagnose.rb
@@ -0,0 +1,167 @@
+# frozen_string_literal: true
+
+require "rbconfig"
+require "shellwords"
+
+module Bundler
+  class CLI::Doctor::Diagnose
+    DARWIN_REGEX = /\s+(.+) \(compatibility /
+    LDD_REGEX = /\t\S+ => (\S+) \(\S+\)/
+
+    attr_reader :options
+
+    def initialize(options)
+      @options = options
+    end
+
+    def otool_available?
+      Bundler.which("otool")
+    end
+
+    def ldd_available?
+      Bundler.which("ldd")
+    end
+
+    def dylibs_darwin(path)
+      output = `/usr/bin/otool -L #{path.shellescape}`.chomp
+      dylibs = output.split("\n")[1..-1].filter_map {|l| l.match(DARWIN_REGEX)&.match(1) }.uniq
+      # ignore @rpath and friends
+      dylibs.reject {|dylib| dylib.start_with? "@" }
+    end
+
+    def dylibs_ldd(path)
+      output = `/usr/bin/ldd #{path.shellescape}`.chomp
+      output.split("\n").filter_map do |l|
+        match = l.match(LDD_REGEX)
+        next if match.nil?
+        match.captures[0]
+      end
+    end
+
+    def dylibs(path)
+      case RbConfig::CONFIG["host_os"]
+      when /darwin/
+        return [] unless otool_available?
+        dylibs_darwin(path)
+      when /(linux|solaris|bsd)/
+        return [] unless ldd_available?
+        dylibs_ldd(path)
+      else # Windows, etc.
+        Bundler.ui.warn("Dynamic library check not supported on this platform.")
+        []
+      end
+    end
+
+    def bundles_for_gem(spec)
+      Dir.glob("#{spec.full_gem_path}/**/*.bundle")
+    end
+
+    def lookup_with_fiddle(path)
+      require "fiddle"
+      Fiddle.dlopen(path)
+      false
+    rescue Fiddle::DLError
+      true
+    end
+
+    def check!
+      require_relative "../check"
+      Bundler::CLI::Check.new({}).run
+    end
+
+    def diagnose_ssl
+      require_relative "ssl"
+      Bundler::CLI::Doctor::SSL.new({}).run
+    end
+
+    def run
+      Bundler.ui.level = "warn" if options[:quiet]
+      Bundler.settings.validate!
+      check!
+      diagnose_ssl if options[:ssl]
+
+      definition = Bundler.definition
+      broken_links = {}
+
+      definition.specs.each do |spec|
+        bundles_for_gem(spec).each do |bundle|
+          bad_paths = dylibs(bundle).select do |f|
+            lookup_with_fiddle(f)
+          end
+          if bad_paths.any?
+            broken_links[spec] ||= []
+            broken_links[spec].concat(bad_paths)
+          end
+        end
+      end
+
+      permissions_valid = check_home_permissions
+
+      if broken_links.any?
+        message = "The following gems are missing OS dependencies:"
+        broken_links.flat_map do |spec, paths|
+          paths.uniq.map do |path|
+            "\n * #{spec.name}: #{path}"
+          end
+        end.sort.each {|m| message += m }
+        raise ProductionError, message
+      elsif permissions_valid
+        Bundler.ui.info "No issues found with the installed bundle"
+      end
+    end
+
+    private
+
+    def check_home_permissions
+      require "find"
+      files_not_readable = []
+      files_not_readable_and_owned_by_different_user = []
+      files_not_owned_by_current_user_but_still_readable = []
+      broken_symlinks = []
+      Find.find(Bundler.bundle_path.to_s).each do |f|
+        if !File.exist?(f)
+          broken_symlinks << f
+        elsif !File.readable?(f)
+          if File.stat(f).uid != Process.uid
+            files_not_readable_and_owned_by_different_user << f
+          else
+            files_not_readable << f
+          end
+        elsif File.stat(f).uid != Process.uid
+          files_not_owned_by_current_user_but_still_readable << f
+        end
+      end
+
+      ok = true
+
+      if broken_symlinks.any?
+        Bundler.ui.warn "Broken links exist in the Bundler home. Please report them to the offending gem's upstream repo. These files are:\n - #{broken_symlinks.join("\n - ")}"
+
+        ok = false
+      end
+
+      if files_not_owned_by_current_user_but_still_readable.any?
+        Bundler.ui.warn "Files exist in the Bundler home that are owned by another " \
+          "user, but are still readable. These files are:\n - #{files_not_owned_by_current_user_but_still_readable.join("\n - ")}"
+
+        ok = false
+      end
+
+      if files_not_readable_and_owned_by_different_user.any?
+        Bundler.ui.warn "Files exist in the Bundler home that are owned by another " \
+          "user, and are not readable. These files are:\n - #{files_not_readable_and_owned_by_different_user.join("\n - ")}"
+
+        ok = false
+      end
+
+      if files_not_readable.any?
+        Bundler.ui.warn "Files exist in the Bundler home that are not " \
+          "readable by the current user. These files are:\n - #{files_not_readable.join("\n - ")}"
+
+        ok = false
+      end
+
+      ok
+    end
+  end
+end
diff --git a/lib/bundler/cli/doctor/ssl.rb b/lib/bundler/cli/doctor/ssl.rb
new file mode 100644
index 0000000000..21fc4edf2d
--- /dev/null
+++ b/lib/bundler/cli/doctor/ssl.rb
@@ -0,0 +1,249 @@
+# frozen_string_literal: true
+
+require "rubygems/remote_fetcher"
+require "uri"
+
+module Bundler
+  class CLI::Doctor::SSL
+    attr_reader :options
+
+    def initialize(options)
+      @options = options
+    end
+
+    def run
+      return unless openssl_installed?
+
+      output_ssl_environment
+      bundler_success = bundler_connection_successful?
+      rubygem_success = rubygem_connection_successful?
+
+      return unless net_http_connection_successful?
+
+      Explanation.summarize(bundler_success, rubygem_success, host)
+    end
+
+    private
+
+    def host
+      @options[:host] || "rubygems.org"
+    end
+
+    def tls_version
+      @options[:"tls-version"].then do |version|
+        "TLS#{version.sub(".", "_")}".to_sym if version
+      end
+    end
+
+    def verify_mode
+      mode = @options[:"verify-mode"] || :peer
+
+      @verify_mode ||= mode.then {|mod| OpenSSL::SSL.const_get("verify_#{mod}".upcase) }
+    end
+
+    def uri
+      @uri ||= URI("https://#{host}")
+    end
+
+    def openssl_installed?
+      require "openssl"
+
+      true
+    rescue LoadError
+      Bundler.ui.warn(<<~MSG)
+        Oh no! Your Ruby doesn't have OpenSSL, so it can't connect to #{host}.
+        You'll need to recompile or reinstall Ruby with OpenSSL support and try again.
+      MSG
+
+      false
+    end
+
+    def output_ssl_environment
+      Bundler.ui.info(<<~MESSAGE)
+        Here's your OpenSSL environment:
+
+        OpenSSL:       #{OpenSSL::VERSION}
+        Compiled with: #{OpenSSL::OPENSSL_VERSION}
+        Loaded with:   #{OpenSSL::OPENSSL_LIBRARY_VERSION}
+      MESSAGE
+    end
+
+    def bundler_connection_successful?
+      Bundler.ui.info("\nTrying connections to #{uri}:\n")
+
+      bundler_uri = Gem::URI(uri.to_s)
+      Bundler::Fetcher.new(
+        Bundler::Source::Rubygems::Remote.new(bundler_uri)
+      ).send(:connection).request(bundler_uri)
+
+      Bundler.ui.info("Bundler:       success")
+
+      true
+    rescue StandardError => error
+      Bundler.ui.warn("Bundler:       failed     (#{Explanation.explain_bundler_or_rubygems_error(error)})")
+
+      false
+    end
+
+    def rubygem_connection_successful?
+      Gem::RemoteFetcher.fetcher.fetch_path(uri)
+      Bundler.ui.info("RubyGems:      success")
+
+      true
+    rescue StandardError => error
+      Bundler.ui.warn("RubyGems:      failed     (#{Explanation.explain_bundler_or_rubygems_error(error)})")
+
+      false
+    end
+
+    def net_http_connection_successful?
+      ::Gem::Net::HTTP.new(uri.host, uri.port).tap do |http|
+        http.use_ssl = true
+        http.min_version = tls_version
+        http.max_version = tls_version
+        http.verify_mode = verify_mode
+      end.start
+
+      Bundler.ui.info("Ruby net/http: success")
+      warn_on_unsupported_tls12
+
+      true
+    rescue StandardError => error
+      Bundler.ui.warn(<<~MSG)
+        Ruby net/http: failed
+
+        Unfortunately, this Ruby can't connect to #{host}.
+
+        #{Explanation.explain_net_http_error(error, host, tls_version)}
+      MSG
+
+      false
+    end
+
+    def warn_on_unsupported_tls12
+      ctx = OpenSSL::SSL::SSLContext.new
+      supported = true
+
+      if ctx.respond_to?(:min_version=)
+        begin
+          ctx.min_version = ctx.max_version = OpenSSL::SSL::TLS1_2_VERSION
+        rescue OpenSSL::SSL::SSLError, NameError
+          supported = false
+        end
+      else
+        supported = OpenSSL::SSL::SSLContext::METHODS.include?(:TLSv1_2) # rubocop:disable Naming/VariableNumber
+      end
+
+      Bundler.ui.warn(<<~EOM) unless supported
+
+        WARNING: Although your Ruby can connect to #{host} today, your OpenSSL is very old!
+        WARNING: You will need to upgrade OpenSSL to use #{host}.
+
+      EOM
+    end
+
+    module Explanation
+      extend self
+
+      def explain_bundler_or_rubygems_error(error)
+        case error.message
+        when /certificate verify failed/
+          "certificate verification"
+        when /read server hello A/
+          "SSL/TLS protocol version mismatch"
+        when /tlsv1 alert protocol version/
+          "requested TLS version is too old"
+        else
+          error.message
+        end
+      end
+
+      def explain_net_http_error(error, host, tls_version)
+        case error.message
+        # Check for certificate errors
+        when /certificate verify failed/
+          <<~MSG
+            #{show_ssl_certs}
+            Your Ruby can't connect to #{host} because you are missing the certificate files OpenSSL needs to verify you are connecting to the genuine #{host} servers.
+          MSG
+        # Check for TLS version errors
+        when /read server hello A/, /tlsv1 alert protocol version/
+          if tls_version.to_s == "TLS1_3"
+            "Your Ruby can't connect to #{host} because #{tls_version} isn't supported yet.\n"
+          else
+            <<~MSG
+              Your Ruby can't connect to #{host} because your version of OpenSSL is too old.
+              You'll need to upgrade your OpenSSL install and/or recompile Ruby to use a newer OpenSSL.
+            MSG
+          end
+        # OpenSSL doesn't support TLS version specified by argument
+        when /unknown SSL method/
+          "Your Ruby can't connect because #{tls_version} isn't supported by your version of OpenSSL."
+        else
+          <<~MSG
+            Even worse, we're not sure why.
+
+            Here's the full error information:
+            #{error.class}: #{error.message}
+              #{error.backtrace.join("\n  ")}
+
+            You might have more luck using Mislav's SSL doctor.rb script. You can get it here:
+            https://github.com/mislav/ssl-tools/blob/8b3dec4/doctor.rb
+
+            Read more about the script and how to use it in this blog post:
+            https://mislav.net/2013/07/ruby-openssl/
+          MSG
+        end
+      end
+
+      def summarize(bundler_success, rubygems_success, host)
+        guide_url = "http://ruby.to/ssl-check-failed"
+
+        message = if bundler_success && rubygems_success
+          <<~MSG
+            Hooray! This Ruby can connect to #{host}.
+            You are all set to use Bundler and RubyGems.
+
+          MSG
+        elsif !bundler_success && !rubygems_success
+          <<~MSG
+            For some reason, your Ruby installation can connect to #{host}, but neither RubyGems nor Bundler can.
+            The most likely fix is to manually upgrade RubyGems by following the instructions at #{guide_url}.
+            After you've done that, run `gem install bundler` to upgrade Bundler, and then run this script again to make sure everything worked. ❣
+
+          MSG
+        elsif !bundler_success
+          <<~MSG
+            Although your Ruby installation and RubyGems can both connect to #{host}, Bundler is having trouble.
+            The most likely way to fix this is to upgrade Bundler by running `gem install bundler`.
+            Run this script again after doing that to make sure everything is all set.
+            If you're still having trouble, check out the troubleshooting guide at #{guide_url}.
+
+          MSG
+        else
+          <<~MSG
+            It looks like Ruby and Bundler can connect to #{host}, but RubyGems itself cannot.
+            You can likely solve this by manually downloading and installing a RubyGems update.
+            Visit #{guide_url} for instructions on how to manually upgrade RubyGems.
+
+          MSG
+        end
+
+        Bundler.ui.info("\n#{message}")
+      end
+
+      private
+
+      def show_ssl_certs
+        ssl_cert_file = ENV["SSL_CERT_FILE"] || OpenSSL::X509::DEFAULT_CERT_FILE
+        ssl_cert_dir  = ENV["SSL_CERT_DIR"]  || OpenSSL::X509::DEFAULT_CERT_DIR
+
+        <<~MSG
+          Below affect only Ruby net/http connections:
+          SSL_CERT_FILE: #{File.exist?(ssl_cert_file) ? "exists     #{ssl_cert_file}" : "is missing #{ssl_cert_file}"}
+          SSL_CERT_DIR:  #{Dir.exist?(ssl_cert_dir)   ? "exists     #{ssl_cert_dir}"  : "is missing #{ssl_cert_dir}"}
+        MSG
+      end
+    end
+  end
+end
diff --git a/lib/bundler/cli/exec.rb b/lib/bundler/cli/exec.rb
new file mode 100644
index 0000000000..2fdc416286
--- /dev/null
+++ b/lib/bundler/cli/exec.rb
@@ -0,0 +1,114 @@
+# frozen_string_literal: true
+
+require_relative "../current_ruby"
+
+module Bundler
+  class CLI::Exec
+    attr_reader :options, :args, :cmd
+
+    TRAPPED_SIGNALS = %w[INT].freeze
+
+    def initialize(options, args)
+      @options = options
+      @cmd = args.shift
+      @args = args
+      @args << { close_others: !options.keep_file_descriptors? } unless Bundler.current_ruby.jruby?
+    end
+
+    def run
+      validate_cmd!
+      SharedHelpers.set_bundle_environment
+      if bin_path = Bundler.which(cmd)
+        if !Bundler.settings[:disable_exec_load] && directly_loadable?(bin_path)
+          bin_path.delete_suffix!(".bat") if Gem.win_platform?
+          kernel_load(bin_path, *args)
+        else
+          bin_path = "./" + bin_path unless File.absolute_path?(bin_path)
+          kernel_exec(bin_path, *args)
+        end
+      else
+        # exec using the given command
+        kernel_exec(cmd, *args)
+      end
+    end
+
+    private
+
+    def validate_cmd!
+      return unless cmd.nil?
+      Bundler.ui.error "bundler: exec needs a command to run"
+      exit 128
+    end
+
+    def kernel_exec(*args)
+      Kernel.exec(*args)
+    rescue Errno::EACCES, Errno::ENOEXEC
+      Bundler.ui.error "bundler: not executable: #{cmd}"
+      exit 126
+    rescue Errno::ENOENT
+      Bundler.ui.error "bundler: command not found: #{cmd}"
+      Bundler.ui.warn "Install missing gem executables with `bundle install`"
+      exit 127
+    end
+
+    def kernel_load(file, *args)
+      args.pop if args.last.is_a?(Hash)
+      ARGV.replace(args)
+      $0 = file
+      Process.setproctitle(process_title(file, args)) if Process.respond_to?(:setproctitle)
+      require_relative "../setup"
+      TRAPPED_SIGNALS.each {|s| trap(s, "DEFAULT") }
+      Kernel.load(file)
+    rescue SystemExit, SignalException
+      raise
+    rescue Exception # rubocop:disable Lint/RescueException
+      Bundler.ui.error "bundler: failed to load command: #{cmd} (#{file})"
+      Bundler::FriendlyErrors.disable!
+      raise
+    end
+
+    def process_title(file, args)
+      "#{file} #{args.join(" ")}".strip
+    end
+
+    def directly_loadable?(file)
+      if Gem.win_platform?
+        script_wrapper?(file)
+      else
+        ruby_shebang?(file)
+      end
+    end
+
+    def script_wrapper?(file)
+      script_file = file.delete_suffix(".bat")
+      return false unless File.exist?(script_file)
+
+      if File.zero?(script_file)
+        Bundler.ui.warn "#{script_file} is empty"
+        return false
+      end
+
+      header = File.open(file, "r") {|f| f.read(32) }
+      ruby_exe = "#{RbConfig::CONFIG["RUBY_INSTALL_NAME"]}#{RbConfig::CONFIG["EXEEXT"]}"
+      ruby_exe = "ruby.exe" if ruby_exe.empty?
+      header.include?(ruby_exe)
+    end
+
+    def ruby_shebang?(file)
+      possibilities = [
+        "#!/usr/bin/env ruby\n",
+        "#!/usr/bin/env jruby\n",
+        "#!/usr/bin/env truffleruby\n",
+        "#!#{Gem.ruby}\n",
+      ]
+
+      if File.zero?(file)
+        Bundler.ui.warn "#{file} is empty"
+        return false
+      end
+
+      first_line = File.open(file, "rb") {|f| f.read(possibilities.map(&:size).max) }
+      possibilities.any? {|shebang| first_line.start_with?(shebang) }
+    end
+  end
+end
diff --git a/lib/bundler/cli/fund.rb b/lib/bundler/cli/fund.rb
new file mode 100644
index 0000000000..ad7f31f3d6
--- /dev/null
+++ b/lib/bundler/cli/fund.rb
@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Fund
+    attr_reader :options
+
+    def initialize(options)
+      @options = options
+    end
+
+    def run
+      Bundler.definition.validate_runtime!
+
+      groups = Array(options[:group]).map(&:to_sym)
+
+      deps = if groups.any?
+        Bundler.definition.dependencies_for(groups)
+      else
+        Bundler.definition.requested_dependencies
+      end
+
+      fund_info = deps.each_with_object([]) do |dep, arr|
+        spec = Bundler.definition.specs[dep.name].first
+        if spec.metadata.key?("funding_uri")
+          arr << "* #{spec.name} (#{spec.version})\n  Funding: #{spec.metadata["funding_uri"]}"
+        end
+      end
+
+      if fund_info.empty?
+        Bundler.ui.info "None of the installed gems you directly depend on are looking for funding."
+      else
+        Bundler.ui.info fund_info.join("\n")
+      end
+    end
+  end
+end
diff --git a/lib/bundler/cli/gem.rb b/lib/bundler/cli/gem.rb
new file mode 100644
index 0000000000..c8c24c8e66
--- /dev/null
+++ b/lib/bundler/cli/gem.rb
@@ -0,0 +1,476 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI
+    Bundler.require_thor_actions
+    include Thor::Actions
+  end
+
+  class CLI::Gem
+    DEFAULT_GITHUB_USERNAME = "[USERNAME]"
+
+    attr_reader :options, :gem_name, :thor, :name, :target, :extension
+
+    def initialize(options, gem_name, thor)
+      @options = options
+      @gem_name = resolve_name(gem_name)
+
+      @thor = thor
+      thor.behavior = :invoke
+      thor.destination_root = nil
+
+      @name = @gem_name
+      @target = Pathname.new(SharedHelpers.pwd).join(gem_name)
+
+      @extension = options[:ext]
+
+      validate_ext_name if @extension
+    end
+
+    def run
+      Bundler.ui.confirm "Creating gem '#{name}'..."
+
+      underscored_name = name.tr("-", "_")
+      namespaced_path = name.tr("-", "/")
+      constant_name = name.gsub(/-[_-]*(?![_-]|$)/) { "::" }.gsub(/([_-]+|(::)|^)(.|$)/) { $2.to_s + $3.upcase }
+      constant_array = constant_name.split("::")
+      minitest_constant_name = constant_array.clone.tap {|a| a[-1] = "Test#{a[-1]}" }.join("::") # Foo::Bar => Foo::TestBar
+
+      use_git = Bundler.git_present? && options[:git]
+
+      git_author_name = use_git ? `git config user.name`.chomp : ""
+      git_username = use_git ? `git config github.user`.chomp : ""
+      git_user_email = use_git ? `git config user.email`.chomp : ""
+      github_username = github_username(git_username)
+
+      if github_username.empty?
+        homepage_uri = "TODO: Put your gem's website or public repo URL here."
+        source_code_uri = "TODO: Put your gem's public repo URL here."
+        changelog_uri = "TODO: Put your gem's CHANGELOG.md URL here."
+      else
+        homepage_uri = "https://github.com/#{github_username}/#{name}"
+        source_code_uri = "https://github.com/#{github_username}/#{name}"
+        changelog_uri = "https://github.com/#{github_username}/#{name}/blob/main/CHANGELOG.md"
+      end
+
+      config = {
+        name: name,
+        underscored_name: underscored_name,
+        namespaced_path: namespaced_path,
+        makefile_path: "#{underscored_name}/#{underscored_name}",
+        constant_name: constant_name,
+        constant_array: constant_array,
+        author: git_author_name.empty? ? "TODO: Write your name" : git_author_name,
+        email: git_user_email.empty? ? "TODO: Write your email address" : git_user_email,
+        test: options[:test],
+        ext: extension,
+        exe: options[:exe],
+        bundle: options[:bundle],
+        bundler_version: bundler_dependency_version,
+        git: use_git,
+        github_username: github_username.empty? ? DEFAULT_GITHUB_USERNAME : github_username,
+        required_ruby_version: required_ruby_version,
+        rust_builder_required_rubygems_version: rust_builder_required_rubygems_version,
+        minitest_constant_name: minitest_constant_name,
+        ignore_paths: %w[bin/],
+        homepage_uri: homepage_uri,
+        source_code_uri: source_code_uri,
+        changelog_uri: changelog_uri,
+      }
+      ensure_safe_gem_name(name, constant_array)
+
+      templates = {
+        "Gemfile.tt" => Bundler.preferred_gemfile_name,
+        "lib/newgem.rb.tt" => "lib/#{namespaced_path}.rb",
+        "lib/newgem/version.rb.tt" => "lib/#{namespaced_path}/version.rb",
+        "sig/newgem.rbs.tt" => "sig/#{namespaced_path}.rbs",
+        "newgem.gemspec.tt" => "#{name}.gemspec",
+        "Rakefile.tt" => "Rakefile",
+        "README.md.tt" => "README.md",
+        "bin/console.tt" => "bin/console",
+        "bin/setup.tt" => "bin/setup",
+      }
+
+      executables = %w[
+        bin/console
+        bin/setup
+      ]
+
+      case Bundler.preferred_gemfile_name
+      when "Gemfile"
+        config[:ignore_paths] << "Gemfile"
+      when "gems.rb"
+        config[:ignore_paths] << "gems.rb"
+        config[:ignore_paths] << "gems.locked"
+      end
+
+      if use_git
+        templates.merge!("gitignore.tt" => ".gitignore")
+        config[:ignore_paths] << ".gitignore"
+      end
+
+      if test_framework = ask_and_set_test_framework
+        config[:test] = test_framework
+
+        case test_framework
+        when "rspec"
+          templates.merge!(
+            "rspec.tt" => ".rspec",
+            "spec/spec_helper.rb.tt" => "spec/spec_helper.rb",
+            "spec/newgem_spec.rb.tt" => "spec/#{namespaced_path}_spec.rb"
+          )
+          config[:test_task] = :spec
+          config[:ignore_paths] << ".rspec"
+          config[:ignore_paths] << "spec/"
+        when "minitest"
+          # Generate path for minitest target file (FileList["test/**/test_*.rb"])
+          #   foo     => test/test_foo.rb
+          #   foo-bar => test/foo/test_bar.rb
+          #   foo_bar => test/test_foo_bar.rb
+          paths = namespaced_path.rpartition("/")
+          paths[2] = "test_#{paths[2]}"
+          minitest_namespaced_path = paths.join("")
+
+          templates.merge!(
+            "test/minitest/test_helper.rb.tt" => "test/test_helper.rb",
+            "test/minitest/test_newgem.rb.tt" => "test/#{minitest_namespaced_path}.rb"
+          )
+          config[:test_task] = :test
+          config[:ignore_paths] << "test/"
+        when "test-unit"
+          templates.merge!(
+            "test/test-unit/test_helper.rb.tt" => "test/test_helper.rb",
+            "test/test-unit/newgem_test.rb.tt" => "test/#{namespaced_path}_test.rb"
+          )
+          config[:test_task] = :test
+          config[:ignore_paths] << "test/"
+        end
+      end
+
+      config[:ci] = ask_and_set_ci
+      case config[:ci]
+      when "github"
+        templates.merge!("github/workflows/main.yml.tt" => ".github/workflows/main.yml")
+        if extension == "rust"
+          templates.merge!("github/workflows/build-gems.yml.tt" => ".github/workflows/build-gems.yml")
+        end
+        config[:ignore_paths] << ".github/"
+      when "gitlab"
+        templates.merge!("gitlab-ci.yml.tt" => ".gitlab-ci.yml")
+        config[:ignore_paths] << ".gitlab-ci.yml"
+      when "circle"
+        templates.merge!("circleci/config.yml.tt" => ".circleci/config.yml")
+        config[:ignore_paths] << ".circleci/"
+      end
+
+      if ask_and_set(:mit, "Do you want to license your code permissively under the MIT license?",
+        "Using a MIT license means that any other developer or company will be legally allowed " \
+        "to use your code for free as long as they admit you created it. You can read more about " \
+        "the MIT license at https://choosealicense.com/licenses/mit.")
+        config[:mit] = true
+        Bundler.ui.info "MIT License enabled in config"
+        templates.merge!("LICENSE.txt.tt" => "LICENSE.txt")
+      end
+
+      if ask_and_set(:coc, "Do you want to include a code of conduct in gems you generate?",
+        "Codes of conduct can increase contributions to your project by contributors who " \
+        "prefer safe, respectful, productive, and collaborative spaces. \n" \
+        "See https://github.com/ruby/rubygems/blob/master/CODE_OF_CONDUCT.md")
+        config[:coc] = true
+        Bundler.ui.info "Code of conduct enabled in config"
+        templates.merge!("CODE_OF_CONDUCT.md.tt" => "CODE_OF_CONDUCT.md")
+      end
+
+      if ask_and_set(:changelog, "Do you want to include a changelog?",
+        "A changelog is a file which contains a curated, chronologically ordered list of notable " \
+        "changes for each version of a project. To make it easier for users and contributors to" \
+        " see precisely what notable changes have been made between each release (or version) of" \
+        " the project. Whether consumers or developers, the end users of software are" \
+        " human beings who care about what's in the software. When the software changes, people " \
+        "want to know why and how. see https://keepachangelog.com")
+        config[:changelog] = true
+        Bundler.ui.info "Changelog enabled in config"
+        templates.merge!("CHANGELOG.md.tt" => "CHANGELOG.md")
+      end
+
+      config[:linter] = ask_and_set_linter
+      case config[:linter]
+      when "rubocop"
+        Bundler.ui.info "RuboCop enabled in config"
+        templates.merge!("rubocop.yml.tt" => ".rubocop.yml")
+        config[:ignore_paths] << ".rubocop.yml"
+      when "standard"
+        Bundler.ui.info "Standard enabled in config"
+        templates.merge!("standard.yml.tt" => ".standard.yml")
+        config[:ignore_paths] << ".standard.yml"
+      end
+
+      if config[:exe]
+        templates.merge!("exe/newgem.tt" => "exe/#{name}")
+        executables.push("exe/#{name}")
+      end
+
+      if extension == "c"
+        templates.merge!(
+          "ext/newgem/extconf-c.rb.tt" => "ext/#{name}/extconf.rb",
+          "ext/newgem/newgem.h.tt" => "ext/#{name}/#{underscored_name}.h",
+          "ext/newgem/newgem.c.tt" => "ext/#{name}/#{underscored_name}.c"
+        )
+      end
+
+      if extension == "rust"
+        templates.merge!(
+          "Cargo.toml.tt" => "Cargo.toml",
+          "ext/newgem/Cargo.toml.tt" => "ext/#{name}/Cargo.toml",
+          "ext/newgem/build.rs.tt" => "ext/#{name}/build.rs",
+          "ext/newgem/extconf-rust.rb.tt" => "ext/#{name}/extconf.rb",
+          "ext/newgem/src/lib.rs.tt" => "ext/#{name}/src/lib.rs",
+        )
+      end
+
+      if extension == "go"
+        templates.merge!(
+          "ext/newgem/go.mod.tt" => "ext/#{name}/go.mod",
+          "ext/newgem/extconf-go.rb.tt" => "ext/#{name}/extconf.rb",
+          "ext/newgem/newgem.h.tt" => "ext/#{name}/#{underscored_name}.h",
+          "ext/newgem/newgem.go.tt" => "ext/#{name}/#{underscored_name}.go",
+          "ext/newgem/newgem-go.c.tt" => "ext/#{name}/#{underscored_name}.c",
+        )
+
+        config[:go_module_username] = config[:github_username] == DEFAULT_GITHUB_USERNAME ? "username" : config[:github_username]
+      end
+
+      if target.exist? && !target.directory?
+        Bundler.ui.error "Couldn't create a new gem named `#{gem_name}` because there's an existing file named `#{gem_name}`."
+        exit Bundler::BundlerError.all_errors[Bundler::GenericSystemCallError]
+      end
+
+      if use_git
+        Bundler.ui.info "\nInitializing git repo in #{target}"
+        require "shellwords"
+        `git init #{target.to_s.shellescape}`
+
+        config[:git_default_branch] = File.read("#{target}/.git/HEAD").split("/").last.chomp
+      end
+
+      templates.each do |src, dst|
+        destination = target.join(dst)
+        thor.template("newgem/#{src}", destination, config)
+      end
+
+      executables.each do |file|
+        path = target.join(file)
+        executable = (path.stat.mode | 0o111)
+        path.chmod(executable)
+      end
+
+      if use_git
+        IO.popen(%w[git add .], { chdir: target }, &:read)
+      end
+
+      if config[:bundle]
+        Bundler.ui.info "Running bundle install in the new gem directory."
+        Dir.chdir(target) do
+          system("bundle install")
+        end
+      end
+
+      # Open gemspec in editor
+      open_editor(options["edit"], target.join("#{name}.gemspec")) if options[:edit]
+
+      Bundler.ui.info "\nGem '#{name}' was successfully created. " \
+        "For more information on making a RubyGem visit https://guides.rubygems.org/make-your-own-gem/"
+    end
+
+    private
+
+    def resolve_name(name)
+      Pathname.new(SharedHelpers.pwd).join(name).basename.to_s
+    end
+
+    def ask_and_set(key, prompt, explanation)
+      choice = options[key]
+      choice = Bundler.settings["gem.#{key}"] if choice.nil?
+
+      if choice.nil?
+        Bundler.ui.info "\n#{explanation}"
+        choice = Bundler.ui.yes? "#{prompt} y/(n):"
+        Bundler.settings.set_global("gem.#{key}", choice)
+      end
+
+      choice
+    end
+
+    def validate_ext_name
+      return unless gem_name.index("-")
+
+      Bundler.ui.error "You have specified a gem name which does not conform to the \n" \
+                       "naming guidelines for C extensions. For more information, \n" \
+                       "see the 'Extension Naming' section at the following URL:\n" \
+                       "https://guides.rubygems.org/gems-with-extensions/\n"
+      exit 1
+    end
+
+    def ask_and_set_test_framework
+      return if skip?(:test)
+      test_framework = options[:test] || Bundler.settings["gem.test"]
+
+      if test_framework.to_s.empty?
+        Bundler.ui.info "\nDo you want to generate tests with your gem?"
+        Bundler.ui.info hint_text("test")
+
+        result = Bundler.ui.ask "Enter a test framework. rspec/minitest/test-unit/(none):"
+        if /rspec|minitest|test-unit/.match?(result)
+          test_framework = result
+        else
+          test_framework = false
+        end
+      end
+
+      if Bundler.settings["gem.test"].nil?
+        Bundler.settings.set_global("gem.test", test_framework)
+      end
+
+      if options[:test] == Bundler.settings["gem.test"]
+        Bundler.ui.info "#{options[:test]} is already configured, ignoring --test flag."
+      end
+
+      test_framework
+    end
+
+    def skip?(option)
+      options.key?(option) && options[option].nil?
+    end
+
+    def hint_text(setting)
+      if Bundler.settings["gem.#{setting}"] == false
+        "Your choice will only be applied to this gem."
+      else
+        "Future `bundle gem` calls will use your choice. " \
+        "This setting can be changed anytime with `bundle config gem.#{setting}`."
+      end
+    end
+
+    def ask_and_set_ci
+      return if skip?(:ci)
+      ci_template = options[:ci] || Bundler.settings["gem.ci"]
+
+      if ci_template.to_s.empty?
+        Bundler.ui.info "\nDo you want to set up continuous integration for your gem? " \
+          "Supported services:\n" \
+          "* CircleCI:       https://circleci.com/\n" \
+          "* GitHub Actions: https://github.com/features/actions\n" \
+          "* GitLab CI:      https://docs.gitlab.com/ee/ci/\n"
+        Bundler.ui.info hint_text("ci")
+
+        result = Bundler.ui.ask "Enter a CI service. github/gitlab/circle/(none):"
+        if /github|gitlab|circle/.match?(result)
+          ci_template = result
+        else
+          ci_template = false
+        end
+      end
+
+      if Bundler.settings["gem.ci"].nil?
+        Bundler.settings.set_global("gem.ci", ci_template)
+      end
+
+      if options[:ci] == Bundler.settings["gem.ci"]
+        Bundler.ui.info "#{options[:ci]} is already configured, ignoring --ci flag."
+      end
+
+      ci_template
+    end
+
+    def ask_and_set_linter
+      return if skip?(:linter)
+      linter_template = options[:linter] || Bundler.settings["gem.linter"]
+
+      if linter_template.to_s.empty?
+        Bundler.ui.info "\nDo you want to add a code linter and formatter to your gem? " \
+          "Supported Linters:\n" \
+          "* RuboCop:       https://rubocop.org\n" \
+          "* Standard:      https://github.com/standardrb/standard\n"
+        Bundler.ui.info hint_text("linter")
+
+        result = Bundler.ui.ask "Enter a linter. rubocop/standard/(none):"
+        if /rubocop|standard/.match?(result)
+          linter_template = result
+        else
+          linter_template = false
+        end
+      end
+
+      if Bundler.settings["gem.linter"].nil?
+        Bundler.settings.set_global("gem.linter", linter_template)
+      end
+
+      # Once gem.linter safely set, unset the deprecated gem.rubocop
+      unless Bundler.settings["gem.rubocop"].nil?
+        Bundler.settings.set_global("gem.rubocop", nil)
+      end
+
+      if options[:linter] == Bundler.settings["gem.linter"]
+        Bundler.ui.info "#{options[:linter]} is already configured, ignoring --linter flag."
+      end
+
+      linter_template
+    end
+
+    def bundler_dependency_version
+      v = Gem::Version.new(Bundler::VERSION)
+      req = v.segments[0..1]
+      req << "a" if v.prerelease?
+      req.join(".")
+    end
+
+    def ensure_safe_gem_name(name, constant_array)
+      if /^\d/.match?(name)
+        Bundler.ui.error "Invalid gem name #{name} Please give a name which does not start with numbers."
+        exit 1
+      end
+
+      if /[A-Z]/.match?(name)
+        Bundler.ui.warn "Gem names with capital letters are not recommended. Please use only lowercase letters, numbers, and hyphens."
+      end
+
+      constant_name = constant_array.join("::")
+
+      existing_constant = constant_array.inject(Object) do |c, s|
+        defined = begin
+          c.const_defined?(s)
+        rescue NameError
+          Bundler.ui.error "Invalid gem name #{name} -- `#{constant_name}` is an invalid constant name"
+          exit 1
+        end
+        (defined && c.const_get(s)) || break
+      end
+
+      return unless existing_constant
+      Bundler.ui.error "Invalid gem name #{name} constant #{constant_name} is already in use. Please choose another gem name."
+      exit 1
+    end
+
+    def open_editor(editor, file)
+      thor.run(%(#{editor} "#{file}"))
+    end
+
+    def rust_builder_required_rubygems_version
+      "3.3.11"
+    end
+
+    def required_ruby_version
+      "3.2.0"
+    end
+
+    def github_username(git_username)
+      if options[:github_username].nil?
+        git_username
+      elsif options[:github_username] == false
+        ""
+      else
+        options[:github_username]
+      end
+    end
+  end
+end
diff --git a/lib/bundler/cli/info.rb b/lib/bundler/cli/info.rb
new file mode 100644
index 0000000000..cd01d4949b
--- /dev/null
+++ b/lib/bundler/cli/info.rb
@@ -0,0 +1,83 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Info
+    attr_reader :gem_name, :options
+    def initialize(options, gem_name)
+      @options = options
+      @gem_name = gem_name
+    end
+
+    def run
+      Bundler.ui.silence do
+        Bundler.definition.validate_runtime!
+        Bundler.load.lock
+      end
+
+      spec = spec_for_gem(gem_name)
+
+      if spec
+        return print_gem_path(spec) if @options[:path]
+        return print_gem_version(spec) if @options[:version]
+        print_gem_info(spec)
+      end
+    end
+
+    private
+
+    def spec_for_gem(name)
+      Bundler::CLI::Common.select_spec(name, :regex_match)
+    end
+
+    def print_gem_version(spec)
+      Bundler.ui.info spec.version.to_s
+    end
+
+    def print_gem_path(spec)
+      name = spec.name
+      if name == "bundler"
+        path = File.expand_path("../../..", __dir__)
+      else
+        path = spec.full_gem_path
+        if spec.installation_missing?
+          return Bundler.ui.warn "The gem #{name} is missing. It should be installed at #{path}, but was not found"
+        end
+      end
+
+      Bundler.ui.info path
+    end
+
+    def print_gem_info(spec)
+      metadata = spec.metadata
+      name = spec.name
+      gem_info = String.new
+      gem_info << "  * #{name} (#{spec.version}#{spec.git_version})\n"
+      gem_info << "\tSummary: #{spec.summary}\n" if spec.summary
+      gem_info << "\tHomepage: #{spec.homepage}\n" if spec.homepage
+      gem_info << "\tDocumentation: #{metadata["documentation_uri"]}\n" if metadata.key?("documentation_uri")
+      gem_info << "\tSource Code: #{metadata["source_code_uri"]}\n" if metadata.key?("source_code_uri")
+      gem_info << "\tFunding: #{metadata["funding_uri"]}\n" if metadata.key?("funding_uri")
+      gem_info << "\tWiki: #{metadata["wiki_uri"]}\n" if metadata.key?("wiki_uri")
+      gem_info << "\tChangelog: #{metadata["changelog_uri"]}\n" if metadata.key?("changelog_uri")
+      gem_info << "\tBug Tracker: #{metadata["bug_tracker_uri"]}\n" if metadata.key?("bug_tracker_uri")
+      gem_info << "\tMailing List: #{metadata["mailing_list_uri"]}\n" if metadata.key?("mailing_list_uri")
+      gem_info << "\tPath: #{spec.full_gem_path}\n"
+      gem_info << "\tDefault Gem: yes\n" if spec.respond_to?(:default_gem?) && spec.default_gem?
+      gem_info << "\tReverse Dependencies: \n\t\t#{gem_dependencies.join("\n\t\t")}" if gem_dependencies.any?
+
+      if name != "bundler" && spec.installation_missing?
+        return Bundler.ui.warn "The gem #{name} is missing. Gemspec information is still available though:\n#{gem_info}"
+      end
+
+      Bundler.ui.info gem_info
+    end
+
+    def gem_dependencies
+      @gem_dependencies ||= Bundler.definition.specs.filter_map do |spec|
+        dependency = spec.dependencies.find {|dep| dep.name == gem_name }
+        next unless dependency
+        "#{spec.name} (#{spec.version}) depends on #{gem_name} (#{dependency.requirements_list.join(", ")})"
+      end.sort
+    end
+  end
+end
diff --git a/lib/bundler/cli/init.rb b/lib/bundler/cli/init.rb
new file mode 100644
index 0000000000..246b9d6460
--- /dev/null
+++ b/lib/bundler/cli/init.rb
@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Init
+    attr_reader :options
+    def initialize(options)
+      @options = options
+    end
+
+    def run
+      if File.exist?(gemfile)
+        Bundler.ui.error "#{gemfile} already exists at #{File.expand_path(gemfile)}"
+        exit 1
+      end
+
+      unless File.writable?(Dir.pwd)
+        Bundler.ui.error "Can not create #{gemfile} as the current directory is not writable."
+        exit 1
+      end
+
+      if options[:gemspec]
+        gemspec = File.expand_path(options[:gemspec])
+        unless File.exist?(gemspec)
+          Bundler.ui.error "Gem specification #{gemspec} doesn't exist"
+          exit 1
+        end
+
+        spec = Bundler.load_gemspec_uncached(gemspec)
+
+        File.open(gemfile, "wb") do |file|
+          file << "# Generated from #{gemspec}\n"
+          file << spec.to_gemfile
+        end
+      else
+        File.open(File.expand_path("../templates/Gemfile", __dir__), "r") do |template|
+          File.open(gemfile, "wb") do |destination|
+            IO.copy_stream(template, destination)
+          end
+        end
+      end
+
+      puts "Writing new #{gemfile} to #{SharedHelpers.pwd}/#{gemfile}"
+    end
+
+    private
+
+    def gemfile
+      @gemfile ||= options[:gemfile] || Bundler.preferred_gemfile_name
+    end
+  end
+end
diff --git a/lib/bundler/cli/install.rb b/lib/bundler/cli/install.rb
new file mode 100644
index 0000000000..69affd1a10
--- /dev/null
+++ b/lib/bundler/cli/install.rb
@@ -0,0 +1,127 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Install
+    attr_reader :options
+    def initialize(options)
+      @options = options
+    end
+
+    def run
+      Bundler.ui.level = "warn" if options[:quiet]
+
+      warn_if_root
+
+      if options[:local]
+        Bundler.self_manager.restart_with_locked_bundler_if_needed
+      else
+        Bundler.self_manager.install_locked_bundler_and_restart_with_it_if_needed
+      end
+
+      Bundler::SharedHelpers.set_env "RB_USER_INSTALL", "1" if Gem.freebsd_platform?
+
+      if target_rbconfig_path = options[:"target-rbconfig"]
+        Bundler.rubygems.set_target_rbconfig(target_rbconfig_path)
+      end
+
+      check_trust_policy
+
+      if Bundler.frozen_bundle? && !Bundler.default_lockfile.exist?
+        flag = "deployment setting" if Bundler.settings[:deployment]
+        flag = "frozen setting" if Bundler.settings[:frozen]
+        raise ProductionError, "The #{flag} requires a lockfile. Please make " \
+                               "sure you have checked your #{SharedHelpers.relative_lockfile_path} into version control " \
+                               "before deploying."
+      end
+
+      normalize_settings
+
+      Bundler::Fetcher.disable_endpoint = options["full-index"]
+
+      Plugin.gemfile_install(Bundler.default_gemfile) if Bundler.settings[:plugins]
+
+      # For install we want to enable strict validation
+      # (rather than some optimizations we perform at app runtime).
+      definition = Bundler.definition(strict: true)
+      definition.validate_runtime!
+      definition.lockfile = options["lockfile"] if options["lockfile"]
+      definition.lockfile = false if options["no-lock"]
+
+      installer = Installer.install(Bundler.root, definition, options)
+
+      Bundler.settings.temporary(cache_all_platforms: options[:local] ? false : Bundler.settings[:cache_all_platforms]) do
+        Bundler.load.cache(nil, options[:local]) if Bundler.app_cache.exist? && !options["no-cache"] && !Bundler.frozen_bundle?
+      end
+
+      Bundler.ui.confirm "Bundle complete! #{dependencies_count_for(definition)}, #{gems_installed_for(definition)}."
+      Bundler::CLI::Common.output_without_groups_message(:install)
+
+      if Bundler.use_system_gems?
+        Bundler.ui.confirm "Use `bundle info [gemname]` to see where a bundled gem is installed."
+      else
+        relative_path = Bundler.configured_bundle_path.base_path_relative_to_pwd
+        Bundler.ui.confirm "Bundled gems are installed into `#{relative_path}`"
+      end
+
+      Bundler::CLI::Common.output_post_install_messages installer.post_install_messages
+
+      if CLI::Common.clean_after_install?
+        require_relative "clean"
+        Bundler::CLI::Clean.new(options).run
+      end
+
+      Bundler::CLI::Common.output_fund_metadata_summary
+    rescue Gem::InvalidSpecificationException
+      Bundler.ui.warn "You have one or more invalid gemspecs that need to be fixed."
+      raise
+    end
+
+    private
+
+    def warn_if_root
+      return if Bundler.settings[:silence_root_warning] || Gem.win_platform? || !Process.uid.zero?
+      Bundler.ui.warn "Don't run Bundler as root. Installing your bundle as root " \
+                      "will break this application for all non-root users on this machine.", wrap: true
+    end
+
+    def dependencies_count_for(definition)
+      count = definition.dependencies.count
+      "#{count} Gemfile #{count == 1 ? "dependency" : "dependencies"}"
+    end
+
+    def gems_installed_for(definition)
+      count = definition.specs.count {|spec| spec.name != "bundler" }
+      "#{count} #{count == 1 ? "gem" : "gems"} now installed"
+    end
+
+    def check_trust_policy
+      trust_policy = options["trust-policy"]
+      unless Bundler.rubygems.security_policies.keys.unshift(nil).include?(trust_policy)
+        raise InvalidOption, "RubyGems doesn't know about trust policy '#{trust_policy}'. " \
+          "The known policies are: #{Bundler.rubygems.security_policies.keys.join(", ")}."
+      end
+      Bundler.settings.set_command_option_if_given :"trust-policy", trust_policy
+    end
+
+    def normalize_settings
+      if options["standalone"] && Bundler.settings[:path].nil? && !options["local"]
+        Bundler.settings.set_command_option :path, "bundle"
+      end
+
+      Bundler.settings.set_command_option_if_given :shebang, options["shebang"]
+
+      Bundler.settings.set_command_option_if_given :jobs, options["jobs"]
+
+      Bundler::CLI::Common.validate_cooldown!(options["cooldown"])
+      Bundler.settings.set_command_option_if_given :cooldown, options["cooldown"]
+
+      Bundler.settings.set_command_option_if_given :no_prune, options["no-prune"]
+
+      Bundler.settings.set_command_option_if_given :no_install, options["no-install"]
+
+      Bundler.settings.set_command_option_if_given :clean, options["clean"]
+
+      options[:force] = options[:redownload] if options[:redownload]
+    end
+  end
+end
diff --git a/lib/bundler/cli/issue.rb b/lib/bundler/cli/issue.rb
new file mode 100644
index 0000000000..cbfb7da2d8
--- /dev/null
+++ b/lib/bundler/cli/issue.rb
@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+require "rbconfig"
+
+module Bundler
+  class CLI::Issue
+    def run
+      Bundler.ui.info <<~EOS
+        Did you find an issue with Bundler? Before filing a new issue,
+        be sure to check out these resources:
+
+        1. Check out our troubleshooting guide for quick fixes to common issues:
+        https://github.com/ruby/rubygems/blob/master/doc/bundler/TROUBLESHOOTING.md
+
+        2. Instructions for common Bundler uses can be found on the documentation
+        site: https://bundler.io/
+
+        3. Information about each Bundler command can be found in the Bundler
+        man pages: https://bundler.io/man/bundle.1.html
+
+        Hopefully the troubleshooting steps above resolved your problem!  If things
+        still aren't working the way you expect them to, please let us know so
+        that we can diagnose and help fix the problem you're having, by filling
+        in the new issue form located at
+        https://github.com/ruby/rubygems/issues/new?labels=Bundler&template=bundler-related-issue.md,
+        and copy and pasting the information below.
+
+      EOS
+
+      Bundler.ui.info Bundler::Env.report
+
+      Bundler.ui.info "\n## Bundle Doctor"
+      doctor
+    end
+
+    def doctor
+      require_relative "doctor/diagnose"
+      Bundler::CLI::Doctor::Diagnose.new({}).run
+    end
+  end
+end
diff --git a/lib/bundler/cli/list.rb b/lib/bundler/cli/list.rb
new file mode 100644
index 0000000000..6a467f45a9
--- /dev/null
+++ b/lib/bundler/cli/list.rb
@@ -0,0 +1,97 @@
+# frozen_string_literal: true
+
+require "json"
+
+module Bundler
+  class CLI::List
+    def initialize(options)
+      @options = options
+      @without_group = options["without-group"].map(&:to_sym)
+      @only_group = options["only-group"].map(&:to_sym)
+      @format = options["format"]
+    end
+
+    def run
+      raise InvalidOption, "The `--only-group` and `--without-group` options cannot be used together" if @only_group.any? && @without_group.any?
+
+      raise InvalidOption, "The `--name-only` and `--paths` options cannot be used together" if @options["name-only"] && @options[:paths]
+
+      specs = if @only_group.any? || @without_group.any?
+        filtered_specs_by_groups
+      else
+        begin
+          Bundler.load.specs
+        rescue GemNotFound => e
+          Bundler.ui.error e.message
+          Bundler.ui.warn "Install missing gems with `bundle install`."
+          exit 1
+        end
+      end.reject {|s| s.name == "bundler" }.sort_by(&:name)
+
+      case @format
+      when "json"
+        print_json(specs: specs)
+      when nil
+        print_human(specs: specs)
+      else
+        raise InvalidOption, "Unknown option`--format=#{@format}`. Supported formats: `json`"
+      end
+    end
+
+    private
+
+    def print_json(specs:)
+      gems = if @options["name-only"]
+        specs.map {|s| { name: s.name } }
+      else
+        specs.map do |s|
+          {
+            name: s.name,
+            version: s.version.to_s,
+            git_version: s.git_version&.strip,
+          }.tap do |h|
+            h[:path] = s.full_gem_path if @options["paths"]
+          end
+        end
+      end
+      Bundler.ui.info({ gems: gems }.to_json)
+    end
+
+    def print_human(specs:)
+      return Bundler.ui.info "No gems in the Gemfile" if specs.empty?
+
+      return specs.each {|s| Bundler.ui.info s.name } if @options["name-only"]
+      return specs.each {|s| Bundler.ui.info s.full_gem_path } if @options["paths"]
+
+      Bundler.ui.info "Gems included by the bundle:"
+
+      specs.each {|s| Bundler.ui.info "  * #{s.name} (#{s.version}#{s.git_version})" }
+
+      Bundler.ui.info "Use `bundle info` to print more detailed information about a gem"
+    end
+
+    def verify_group_exists(groups)
+      (@without_group + @only_group).each do |group|
+        raise InvalidOption, "`#{group}` group could not be found." unless groups.include?(group)
+      end
+    end
+
+    def filtered_specs_by_groups
+      definition = Bundler.definition
+      groups = definition.groups
+
+      verify_group_exists(groups)
+
+      show_groups =
+        if @without_group.any?
+          groups.reject {|g| @without_group.include?(g) }
+        elsif @only_group.any?
+          groups.select {|g| @only_group.include?(g) }
+        else
+          groups
+        end.map(&:to_sym)
+
+      definition.specs_for(show_groups)
+    end
+  end
+end
diff --git a/lib/bundler/cli/lock.rb b/lib/bundler/cli/lock.rb
new file mode 100644
index 0000000000..2f78868936
--- /dev/null
+++ b/lib/bundler/cli/lock.rb
@@ -0,0 +1,94 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Lock
+    attr_reader :options
+
+    def initialize(options)
+      @options = options
+    end
+
+    def run
+      unless Bundler.default_gemfile
+        Bundler.ui.error "Unable to find a Gemfile to lock"
+        exit 1
+      end
+
+      check_for_conflicting_options
+
+      print = options[:print]
+      previous_output_stream = Bundler.ui.output_stream
+      Bundler.ui.output_stream = :stderr if print
+
+      Bundler::Fetcher.disable_endpoint = options["full-index"]
+
+      update = options[:update]
+      conservative = options[:conservative]
+      bundler = options[:bundler]
+
+      if update.is_a?(Array) # unlocking specific gems
+        Bundler::CLI::Common.ensure_all_gems_in_lockfile!(update)
+        update = { gems: update, conservative: conservative }
+      elsif update && conservative
+        update = { conservative: conservative }
+      elsif update && bundler
+        update = { bundler: bundler }
+      end
+
+      Bundler.settings.temporary(frozen: false) do
+        definition = Bundler.definition(update, Bundler.default_lockfile)
+        definition.add_checksums if options["add-checksums"]
+
+        Bundler::CLI::Common.configure_gem_version_promoter(definition, options) if options[:update]
+
+        options["remove-platform"].each do |platform_string|
+          platform = Gem::Platform.new(platform_string)
+          definition.remove_platform(platform)
+        end
+
+        options["add-platform"].each do |platform_string|
+          platform = Gem::Platform.new(platform_string)
+          if platform.to_s == "unknown"
+            Bundler.ui.error "The platform `#{platform_string}` is unknown to RubyGems and can't be added to the lockfile."
+            exit 1
+          end
+          definition.add_platform(platform)
+        end
+
+        if definition.platforms.empty?
+          raise InvalidOption, "Removing all platforms from the bundle is not allowed"
+        end
+
+        definition.remotely! unless options[:local]
+
+        if options["normalize-platforms"]
+          definition.normalize_platforms
+        end
+
+        if print
+          puts definition.to_lock
+        else
+          file = options[:lockfile]
+          file = file ? Pathname.new(file).expand_path : Bundler.default_lockfile
+
+          puts "Writing lockfile to #{file}"
+          definition.write_lock(file, false)
+        end
+      end
+
+      Bundler.ui.output_stream = previous_output_stream
+    end
+
+    private
+
+    def check_for_conflicting_options
+      if options["normalize-platforms"] && options["add-platform"].any?
+        raise InvalidOption, "--normalize-platforms can't be used with --add-platform"
+      end
+
+      if options["normalize-platforms"] && options["remove-platform"].any?
+        raise InvalidOption, "--normalize-platforms can't be used with --remove-platform"
+      end
+    end
+  end
+end
diff --git a/lib/bundler/cli/open.rb b/lib/bundler/cli/open.rb
new file mode 100644
index 0000000000..f24693b843
--- /dev/null
+++ b/lib/bundler/cli/open.rb
@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Open
+    attr_reader :options, :name, :path
+    def initialize(options, name)
+      @options = options
+      @name = name
+      @path = options[:path] unless options[:path].nil?
+    end
+
+    def run
+      raise InvalidOption, "Cannot specify `--path` option without a value" if !@path.nil? && @path.empty?
+      editor = [ENV["BUNDLER_EDITOR"], ENV["VISUAL"], ENV["EDITOR"]].find {|e| !e.nil? && !e.empty? }
+      return Bundler.ui.info("To open a bundled gem, set $EDITOR or $BUNDLER_EDITOR") unless editor
+      return unless spec = Bundler::CLI::Common.select_spec(name, :regex_match)
+      if spec.default_gem?
+        Bundler.ui.info "Unable to open #{name} because it's a default gem, so the directory it would normally be installed to does not exist."
+      else
+        root_path = spec.full_gem_path
+        require "shellwords"
+        command = Shellwords.split(editor) << File.join([root_path, path].compact)
+        Bundler.with_original_env do
+          system(*command, { chdir: root_path })
+        end || Bundler.ui.info("Could not run '#{command.join(" ")}'")
+      end
+    end
+  end
+end
diff --git a/lib/bundler/cli/outdated.rb b/lib/bundler/cli/outdated.rb
new file mode 100644
index 0000000000..465e56ada2
--- /dev/null
+++ b/lib/bundler/cli/outdated.rb
@@ -0,0 +1,337 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Outdated
+    attr_reader :options, :gems, :options_include_groups, :filter_options_patch, :sources, :strict
+    attr_accessor :outdated_gems
+
+    def initialize(options, gems)
+      @options = options
+      @gems = gems
+      @sources = Array(options[:source])
+
+      @filter_options_patch = options.keys & %w[filter-major filter-minor filter-patch]
+
+      @outdated_gems = []
+
+      @options_include_groups = [:group, :groups].any? do |v|
+        options.keys.include?(v.to_s)
+      end
+
+      # the patch level options imply strict is also true. It wouldn't make
+      # sense otherwise.
+      @strict = options["filter-strict"] || Bundler::CLI::Common.patch_level_options(options).any?
+    end
+
+    def run
+      check_for_deployment_mode!
+
+      Bundler::CLI::Common.validate_cooldown!(options[:cooldown])
+      Bundler.settings.set_command_option_if_given :cooldown, options[:cooldown]
+
+      Bundler.definition.validate_runtime!
+      current_specs = Bundler.ui.silence { Bundler.definition.resolve }
+
+      gems.each do |gem_name|
+        if current_specs[gem_name].empty?
+          raise GemNotFound, "Could not find gem '#{gem_name}'."
+        end
+      end
+
+      current_dependencies = Bundler.ui.silence do
+        Bundler.load.dependencies.map {|dep| [dep.name, dep] }.to_h
+      end
+
+      definition = if gems.empty? && sources.empty?
+        # We're doing a full update
+        Bundler.definition(true)
+      else
+        Bundler.definition(gems: gems, sources: sources)
+      end
+
+      Bundler::CLI::Common.configure_gem_version_promoter(
+        Bundler.definition,
+        options.merge(strict: @strict)
+      )
+
+      definition_resolution = proc do
+        options[:local] ? definition.resolve_with_cache! : definition.resolve_remotely!
+      end
+
+      if options[:parseable]
+        Bundler.ui.progress(&definition_resolution)
+      else
+        definition_resolution.call
+      end
+
+      Bundler.ui.info ""
+
+      # Loop through the current specs
+      gemfile_specs, dependency_specs = current_specs.partition do |spec|
+        current_dependencies.key? spec.name
+      end
+
+      specs = if options["only-explicit"]
+        gemfile_specs
+      else
+        gemfile_specs + dependency_specs
+      end
+
+      specs.sort_by(&:name).uniq(&:name).each do |current_spec|
+        next unless gems.empty? || gems.include?(current_spec.name)
+
+        active_spec = retrieve_active_spec(definition, current_spec)
+        next unless active_spec
+
+        next unless filter_options_patch.empty? || update_present_via_semver_portions(current_spec, active_spec, options)
+
+        gem_outdated = Gem::Version.new(active_spec.version) > Gem::Version.new(current_spec.version)
+        next unless gem_outdated || (current_spec.git_version != active_spec.git_version)
+
+        dependency = current_dependencies[current_spec.name]
+        groups = ""
+        if dependency && !options[:parseable]
+          groups = dependency.groups.join(", ")
+        end
+
+        outdated_gems << {
+          active_spec: active_spec,
+          current_spec: current_spec,
+          dependency: dependency,
+          groups: groups,
+        }
+      end
+
+      relevant_outdated_gems = if options_include_groups
+        outdated_gems.group_by {|g| g[:groups] }.sort.flat_map do |groups, gems|
+          contains_group = groups.split(", ").include?(options[:group])
+          next unless options[:groups] || contains_group
+
+          gems
+        end.compact
+      else
+        outdated_gems
+      end
+
+      if relevant_outdated_gems.empty?
+        unless options[:parseable]
+          Bundler.ui.info(nothing_outdated_message)
+        end
+      else
+        if options[:parseable]
+          print_gems(relevant_outdated_gems)
+        else
+          print_gems_table(relevant_outdated_gems)
+        end
+
+        exit 1
+      end
+    end
+
+    private
+
+    def loaded_from_for(spec)
+      return unless spec.respond_to?(:loaded_from)
+
+      spec.loaded_from
+    end
+
+    def groups_text(group_text, groups)
+      "#{group_text}#{groups.split(",").size > 1 ? "s" : ""} \"#{groups}\""
+    end
+
+    def nothing_outdated_message
+      if filter_options_patch.any?
+        display = filter_options_patch.map do |o|
+          o.sub("filter-", "")
+        end.join(" or ")
+
+        "No #{display} updates to display.\n"
+      else
+        "Bundle up to date!\n"
+      end
+    end
+
+    def retrieve_active_spec(definition, current_spec)
+      active_spec = definition.resolve.find_by_name_and_platform(current_spec.name, current_spec.platform)
+      return unless active_spec
+
+      return active_spec if strict
+
+      active_specs = active_spec.source.specs.search(current_spec.name).select {|spec| spec.installable_on_platform?(current_spec.platform) }.sort_by(&:version)
+      if !current_spec.version.prerelease? && !options[:pre] && active_specs.size > 1
+        active_specs.delete_if {|b| b.respond_to?(:version) && b.version.prerelease? }
+      end
+      active_specs.last
+    end
+
+    def print_gems(gems_list)
+      gems_list.each do |gem|
+        print_gem(
+          gem[:current_spec],
+          gem[:active_spec],
+          gem[:dependency],
+          gem[:groups],
+        )
+      end
+    end
+
+    def print_gems_table(gems_list)
+      data = gems_list.map do |gem|
+        gem_column_for(
+          gem[:current_spec],
+          gem[:active_spec],
+          gem[:dependency],
+          gem[:groups],
+        )
+      end
+
+      print_indented([table_header] + data)
+    end
+
+    def print_gem(current_spec, active_spec, dependency, groups)
+      spec_version = "#{active_spec.version}#{active_spec.git_version}"
+      if Bundler.ui.debug?
+        loaded_from = loaded_from_for(active_spec)
+        spec_version += " (from #{loaded_from})" if loaded_from
+      end
+      current_version = "#{current_spec.version}#{current_spec.git_version}"
+
+      if dependency&.specific?
+        dependency_version = %(, requested #{dependency.requirement})
+      end
+
+      spec_outdated_info = "#{active_spec.name} (newest #{spec_version}, " \
+        "installed #{current_version}#{dependency_version}"
+
+      release_date = release_date_for(active_spec)
+      spec_outdated_info += ", released #{release_date}" unless release_date.empty?
+
+      remaining = cooldown_days_remaining(active_spec)
+      spec_outdated_info += ", in cooldown for #{remaining} more day#{"s" if remaining > 1}" if remaining
+
+      spec_outdated_info += ")"
+
+      output_message = if options[:parseable]
+        spec_outdated_info.to_s
+      elsif options_include_groups || groups.empty?
+        "  * #{spec_outdated_info}"
+      else
+        "  * #{spec_outdated_info} in #{groups_text("group", groups)}"
+      end
+
+      Bundler.ui.info output_message.rstrip
+    end
+
+    def gem_column_for(current_spec, active_spec, dependency, groups)
+      current_version = "#{current_spec.version}#{current_spec.git_version}"
+      spec_version = "#{active_spec.version}#{active_spec.git_version}"
+      remaining = cooldown_days_remaining(active_spec)
+      spec_version += " (cooldown #{remaining}d)" if remaining
+      dependency = dependency.requirement if dependency
+
+      ret_val = [active_spec.name, current_version, spec_version, dependency.to_s, groups.to_s]
+      ret_val << release_date_for(active_spec)
+      ret_val << loaded_from_for(active_spec).to_s if Bundler.ui.debug?
+      ret_val
+    end
+
+    def cooldown_days_remaining(spec, now = Time.now)
+      return nil unless spec.respond_to?(:created_at) && spec.created_at
+      return nil unless spec.respond_to?(:remote) && spec.remote
+      days = spec.remote.effective_cooldown
+      return nil if days.nil? || days <= 0
+      remaining = days - ((now - spec.created_at) / 86_400.0)
+      remaining > 0 ? remaining.ceil : nil
+    end
+
+    def check_for_deployment_mode!
+      return unless Bundler.frozen_bundle?
+      suggested_command = if Bundler.settings.locations("frozen").keys.&([:global, :local]).any?
+        "bundle config unset frozen"
+      elsif Bundler.settings.locations("deployment").keys.&([:global, :local]).any?
+        "bundle config unset deployment"
+      end
+      raise ProductionError, "You are trying to check outdated gems in " \
+        "deployment mode. Run `bundle outdated` elsewhere.\n" \
+        "\nIf this is a development machine, remove the " \
+        "#{Bundler.default_gemfile} freeze" \
+        "\nby running `#{suggested_command}`."
+    end
+
+    def update_present_via_semver_portions(current_spec, active_spec, options)
+      current_major = current_spec.version.segments.first
+      active_major = active_spec.version.segments.first
+
+      update_present = false
+      update_present = active_major > current_major if options["filter-major"]
+
+      if !update_present && (options["filter-minor"] || options["filter-patch"]) && current_major == active_major
+        current_minor = get_version_semver_portion_value(current_spec, 1)
+        active_minor = get_version_semver_portion_value(active_spec, 1)
+
+        update_present = active_minor > current_minor if options["filter-minor"]
+
+        if !update_present && options["filter-patch"] && current_minor == active_minor
+          current_patch = get_version_semver_portion_value(current_spec, 2)
+          active_patch = get_version_semver_portion_value(active_spec, 2)
+
+          update_present = active_patch > current_patch
+        end
+      end
+
+      update_present
+    end
+
+    def get_version_semver_portion_value(spec, version_portion_index)
+      version_section = spec.version.segments[version_portion_index, 1]
+      version_section.to_a[0].to_i
+    end
+
+    def print_indented(matrix)
+      header = matrix[0]
+      data = matrix[1..-1]
+
+      column_sizes = Array.new(header.size) do |index|
+        matrix.max_by {|row| row[index].length }[index].length
+      end
+
+      Bundler.ui.info justify(header, column_sizes)
+
+      data.sort_by! {|row| row[0] }
+
+      data.each do |row|
+        Bundler.ui.info justify(row, column_sizes)
+      end
+    end
+
+    def table_header
+      header = ["Gem", "Current", "Latest", "Requested", "Groups", "Release Date"]
+      header << "Path" if Bundler.ui.debug?
+      header
+    end
+
+    def release_date_for(spec)
+      return "" unless spec.respond_to?(:date)
+
+      date = spec.date
+      return "" unless date
+
+      return "" unless Gem.const_defined?(:DEFAULT_SOURCE_DATE_EPOCH)
+      default_date = Time.at(Gem::DEFAULT_SOURCE_DATE_EPOCH).utc
+      default_date = Time.utc(default_date.year, default_date.month, default_date.day)
+
+      date = date.utc if date.respond_to?(:utc)
+
+      return "" if date == default_date
+
+      date.strftime("%Y-%m-%d")
+    end
+
+    def justify(row, sizes)
+      row.each_with_index.map do |element, index|
+        element.ljust(sizes[index])
+      end.join("  ").strip + "\n"
+    end
+  end
+end
diff --git a/lib/bundler/cli/platform.rb b/lib/bundler/cli/platform.rb
new file mode 100644
index 0000000000..32d68abbb1
--- /dev/null
+++ b/lib/bundler/cli/platform.rb
@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Platform
+    attr_reader :options
+    def initialize(options)
+      @options = options
+    end
+
+    def run
+      ruby_version = if Bundler.locked_gems
+        Bundler.locked_gems.ruby_version&.gsub(/p\d+\Z/, "")
+      else
+        Bundler.definition.ruby_version&.single_version_string
+      end
+
+      output = []
+
+      if options[:ruby]
+        if ruby_version
+          output << ruby_version
+        else
+          output << "No ruby version specified"
+        end
+      else
+        platforms = Bundler.definition.platforms.map {|p| "* #{p}" }
+
+        output << "Your platform is: #{Gem::Platform.local}"
+        output << "Your app has gems that work on these platforms:\n#{platforms.join("\n")}"
+
+        if ruby_version
+          output << "Your Gemfile specifies a Ruby version requirement:\n* #{ruby_version}"
+
+          begin
+            Bundler.definition.validate_runtime!
+            output << "Your current platform satisfies the Ruby version requirement."
+          rescue RubyVersionMismatch => e
+            output << e.message
+          end
+        else
+          output << "Your Gemfile does not specify a Ruby version requirement."
+        end
+      end
+
+      Bundler.ui.info output.join("\n\n")
+    end
+  end
+end
diff --git a/lib/bundler/cli/plugin.rb b/lib/bundler/cli/plugin.rb
new file mode 100644
index 0000000000..32fa660fe0
--- /dev/null
+++ b/lib/bundler/cli/plugin.rb
@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+require_relative "../vendored_thor"
+module Bundler
+  class CLI::Plugin < Thor
+    desc "install PLUGINS", "Install the plugin from the source"
+    long_desc <<-D
+      Install plugins either from the rubygems source provided (with --source option), from a git source provided with --git, or a local path provided with --path. If no sources are provided, it uses Gem.sources
+   D
+    method_option "source", type: :string, default: nil, banner: "URL of the RubyGems source to fetch the plugin from"
+    method_option "version", type: :string, default: nil, banner: "The version of the plugin to fetch"
+    method_option "git", type: :string, default: nil, banner: "URL of the git repo to fetch from"
+    method_option "local_git", type: :string, default: nil, banner: "Path of the local git repo to fetch from (removed)"
+    method_option "branch", type: :string, default: nil, banner: "The git branch to checkout"
+    method_option "ref", type: :string, default: nil, banner: "The git revision to check out"
+    method_option "path", type: :string, default: nil, banner: "Path of a local gem to directly use"
+    def install(*plugins)
+      if options.key?(:local_git)
+        raise InvalidOption, "--local_git has been removed, use --git"
+      end
+
+      Bundler::Plugin.install(plugins, options)
+    end
+
+    desc "uninstall PLUGINS", "Uninstall the plugins"
+    long_desc <<-D
+      Uninstall given list of plugins. To uninstall all the plugins, use -all option.
+    D
+    method_option "all", type: :boolean, default: nil, banner: "Uninstall all the installed plugins. If no plugin is installed, then it does nothing."
+    def uninstall(*plugins)
+      Bundler::Plugin.uninstall(plugins, options)
+    end
+
+    desc "list", "List the installed plugins and available commands"
+    def list
+      Bundler::Plugin.list
+    end
+  end
+end
diff --git a/lib/bundler/cli/pristine.rb b/lib/bundler/cli/pristine.rb
new file mode 100644
index 0000000000..f463f0bce8
--- /dev/null
+++ b/lib/bundler/cli/pristine.rb
@@ -0,0 +1,64 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Pristine
+    def initialize(gems)
+      @gems = gems
+    end
+
+    def run
+      CLI::Common.ensure_all_gems_in_lockfile!(@gems)
+      definition = Bundler.definition
+      definition.validate_runtime!
+      installer = Bundler::Installer.new(Bundler.root, definition)
+      git_sources = []
+
+      ProcessLock.lock do
+        installed_specs = definition.specs.reject do |spec|
+          next if spec.name == "bundler" # Source::Rubygems doesn't install bundler
+          next if !@gems.empty? && !@gems.include?(spec.name)
+
+          gem_name = "#{spec.name} (#{spec.version}#{spec.git_version})"
+          gem_name += " (#{spec.platform})" if !spec.platform.nil? && spec.platform != Gem::Platform::RUBY
+
+          case source = spec.source
+          when Source::Rubygems
+            cached_gem = spec.cache_file
+            unless File.exist?(cached_gem)
+              Bundler.ui.error("Failed to pristine #{gem_name}. Cached gem #{cached_gem} does not exist.")
+              next
+            end
+
+            FileUtils.rm_rf spec.full_gem_path
+          when Source::Git
+            if source.local?
+              Bundler.ui.warn("Cannot pristine #{gem_name}. Gem is locally overridden.")
+              next
+            end
+
+            source.remote!
+            if extension_cache_path = source.extension_cache_path(spec)
+              FileUtils.rm_rf extension_cache_path
+            end
+            FileUtils.rm_rf spec.extension_dir
+            FileUtils.rm_rf spec.full_gem_path
+
+            next if git_sources.include?(source)
+            git_sources << source
+          else
+            Bundler.ui.warn("Cannot pristine #{gem_name}. Gem is sourced from local path.")
+            next
+          end
+
+          true
+        end.map(&:name)
+
+        jobs = Bundler.settings.installation_parallelization
+        pristine_count = definition.specs.count - installed_specs.count
+        # allow a pristining a single gem to skip the parallel worker
+        jobs = [jobs, pristine_count].min
+        ParallelInstaller.call(installer, definition.specs, jobs, false, true, skip: installed_specs)
+      end
+    end
+  end
+end
diff --git a/lib/bundler/cli/remove.rb b/lib/bundler/cli/remove.rb
new file mode 100644
index 0000000000..44a4d891dd
--- /dev/null
+++ b/lib/bundler/cli/remove.rb
@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Remove
+    def initialize(gems, options)
+      @gems = gems
+      @options = options
+    end
+
+    def run
+      raise InvalidOption, "Please specify gems to remove." if @gems.empty?
+
+      Injector.remove(@gems, {})
+      Installer.install(Bundler.root, Bundler.definition)
+    end
+  end
+end
diff --git a/lib/bundler/cli/show.rb b/lib/bundler/cli/show.rb
new file mode 100644
index 0000000000..67fdcc797e
--- /dev/null
+++ b/lib/bundler/cli/show.rb
@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Show
+    attr_reader :options, :gem_name, :latest_specs
+    def initialize(options, gem_name)
+      @options = options
+      @gem_name = gem_name
+      @verbose = options[:verbose]
+      @latest_specs = fetch_latest_specs if @verbose
+    end
+
+    def run
+      Bundler.ui.silence do
+        Bundler.definition.validate_runtime!
+        Bundler.load.lock
+      end
+
+      if gem_name
+        if gem_name == "bundler"
+          path = File.expand_path("../../..", __dir__)
+        else
+          spec = Bundler::CLI::Common.select_spec(gem_name, :regex_match)
+          return unless spec
+          path = spec.full_gem_path
+          unless File.directory?(path)
+            return Bundler.ui.warn "The gem #{gem_name} is missing. It should be installed at #{path}, but was not found"
+          end
+        end
+        return Bundler.ui.info(path)
+      end
+
+      if options[:paths]
+        Bundler.load.specs.sort_by(&:name).map do |s|
+          Bundler.ui.info s.full_gem_path
+        end
+      else
+        Bundler.ui.info "Gems included by the bundle:"
+        Bundler.load.specs.sort_by(&:name).each do |s|
+          desc = "  * #{s.name} (#{s.version}#{s.git_version})"
+          if @verbose
+            latest = latest_specs.find {|l| l.name == s.name }
+            Bundler.ui.info <<~END
+              #{desc.lstrip}
+              \tSummary:  #{s.summary || "No description available."}
+              \tHomepage: #{s.homepage || "No website available."}
+              \tStatus:   #{outdated?(s, latest) ? "Outdated - #{s.version} < #{latest.version}" : "Up to date"}
+            END
+          else
+            Bundler.ui.info desc
+          end
+        end
+      end
+    end
+
+    private
+
+    def fetch_latest_specs
+      definition = Bundler.definition(true)
+      Bundler.ui.info "Fetching remote specs for outdated check...\n\n"
+      Bundler.ui.silence { definition.remotely! }
+      Bundler.reset!
+      definition.specs
+    end
+
+    def outdated?(current, latest)
+      return false unless latest
+      Gem::Version.new(current.version) < Gem::Version.new(latest.version)
+    end
+  end
+end
diff --git a/lib/bundler/cli/update.rb b/lib/bundler/cli/update.rb
new file mode 100644
index 0000000000..d92ffd995f
--- /dev/null
+++ b/lib/bundler/cli/update.rb
@@ -0,0 +1,125 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Update
+    attr_reader :options, :gems
+    def initialize(options, gems)
+      @options = options
+      @gems = gems
+    end
+
+    def run
+      Bundler.ui.level = "warn" if options[:quiet]
+
+      update_bundler = options[:bundler]
+
+      Bundler.self_manager.update_bundler_and_restart_with_it_if_needed(update_bundler) if update_bundler
+
+      Plugin.gemfile_install(Bundler.default_gemfile) if Bundler.settings[:plugins]
+
+      sources = Array(options[:source])
+      groups  = Array(options[:group]).map(&:to_sym)
+
+      full_update = gems.empty? && sources.empty? && groups.empty? && !options[:ruby] && !update_bundler
+
+      if full_update && !options[:all]
+        if Bundler.settings[:update_requires_all_flag]
+          raise InvalidOption, "To update everything, pass the `--all` flag."
+        end
+        SharedHelpers.feature_deprecated! "Pass --all to `bundle update` to update everything"
+      elsif !full_update && options[:all]
+        raise InvalidOption, "Cannot specify --all along with specific options."
+      end
+
+      conservative = options[:conservative]
+
+      if full_update
+        if conservative
+          Bundler.definition(conservative: conservative)
+        else
+          Bundler.definition(true)
+        end
+      else
+        unless Bundler.default_lockfile.exist?
+          raise GemfileLockNotFound, "This Bundle hasn't been installed yet. " \
+            "Run `bundle install` to update and install the bundled gems."
+        end
+        Bundler::CLI::Common.ensure_all_gems_in_lockfile!(gems)
+
+        if groups.any?
+          deps = Bundler.definition.dependencies.select {|d| (d.groups & groups).any? }
+          gems.concat(deps.map(&:name))
+        end
+
+        Bundler.definition(gems: gems, sources: sources, ruby: options[:ruby],
+                           conservative: conservative,
+                           bundler: update_bundler)
+      end
+
+      Bundler::CLI::Common.configure_gem_version_promoter(Bundler.definition, options)
+
+      Bundler::Fetcher.disable_endpoint = options["full-index"]
+
+      opts = options.dup
+      opts["update"] = true
+      opts["local"] = options[:local]
+      opts["force"] = options[:redownload] if options[:redownload]
+
+      Bundler.settings.set_command_option_if_given :jobs, opts["jobs"]
+      Bundler::CLI::Common.validate_cooldown!(options[:cooldown])
+      Bundler.settings.set_command_option_if_given :cooldown, options[:cooldown]
+
+      Bundler.definition.validate_runtime!
+
+      if locked_gems = Bundler.definition.locked_gems
+        previous_locked_info = locked_gems.specs.reduce({}) do |h, s|
+          h[s.name] = { spec: s, version: s.version, source: s.source.identifier }
+          h
+        end
+      end
+
+      installer = Installer.install Bundler.root, Bundler.definition, opts
+      Bundler.load.cache if Bundler.app_cache.exist?
+
+      if CLI::Common.clean_after_install?
+        require_relative "clean"
+        Bundler::CLI::Clean.new(options).run
+      end
+
+      if locked_gems
+        gems.each do |name|
+          locked_info = previous_locked_info[name]
+          next unless locked_info
+
+          locked_spec = locked_info[:spec]
+          new_spec = Bundler.definition.specs[name].first
+          unless new_spec
+            unless locked_spec.installable_on_platform?(Bundler.local_platform)
+              Bundler.ui.warn "Bundler attempted to update #{name} but it was not considered because it is for a different platform from the current one"
+            end
+
+            next
+          end
+
+          locked_source = locked_info[:source]
+          new_source = new_spec.source.identifier
+          next if locked_source != new_source
+
+          new_version = new_spec.version
+          locked_version = locked_info[:version]
+          if new_version < locked_version
+            Bundler.ui.warn "Note: #{name} version regressed from #{locked_version} to #{new_version}"
+          elsif new_version == locked_version
+            Bundler.ui.warn "Bundler attempted to update #{name} but its version stayed the same"
+          end
+        end
+      end
+
+      Bundler.ui.confirm "Bundle updated!"
+      Bundler::CLI::Common.output_without_groups_message(:update)
+      Bundler::CLI::Common.output_post_install_messages installer.post_install_messages
+
+      Bundler::CLI::Common.output_fund_metadata_summary
+    end
+  end
+end
diff --git a/lib/bundler/compact_index_client.rb b/lib/bundler/compact_index_client.rb
new file mode 100644
index 0000000000..6865e30dbc
--- /dev/null
+++ b/lib/bundler/compact_index_client.rb
@@ -0,0 +1,92 @@
+# frozen_string_literal: true
+
+require "set"
+
+module Bundler
+  # The CompactIndexClient is responsible for fetching and parsing the compact index.
+  #
+  # The compact index is a set of caching optimized files that are used to fetch gem information.
+  # The files are:
+  # - names: a list of all gem names
+  # - versions: a list of all gem versions
+  # - info/[gem]: a list of all versions of a gem
+  #
+  # The client is instantiated with:
+  # - `directory`: the root directory where the cache files are stored.
+  # - `fetcher`: (optional) an object that responds to #call(uri_path, headers) and returns an http response.
+  # If the `fetcher` is not provided, the client will only read cached files from disk.
+  #
+  # The client is organized into:
+  # - `Updater`: updates the cached files on disk using the fetcher.
+  # - `Cache`: calls the updater, caches files, read and return them from disk
+  # - `Parser`: parses the compact index file data
+  # - `CacheFile`: a concurrency safe file reader/writer that verifies checksums
+  #
+  # The client is intended to optimize memory usage and performance.
+  # It is called 100s or 1000s of times, parsing files with hundreds of thousands of lines.
+  # It may be called concurrently without global interpreter lock in some Rubies.
+  # As a result, some methods may look more complex than necessary to save memory or time.
+  class CompactIndexClient
+    SUPPORTED_DIGESTS = { "sha-256" => :SHA256 }.freeze
+    DEBUG_MUTEX = Thread::Mutex.new
+
+    # info returns an Array of INFO Arrays. Each INFO Array has the following indices:
+    INFO_NAME = 0
+    INFO_VERSION = 1
+    INFO_PLATFORM = 2
+    INFO_DEPS = 3
+    INFO_REQS = 4
+
+    def self.debug
+      return unless ENV["DEBUG_COMPACT_INDEX"]
+      DEBUG_MUTEX.synchronize { warn("[#{self}] #{yield}") }
+    end
+
+    class Error < StandardError; end
+
+    require_relative "compact_index_client/cache"
+    require_relative "compact_index_client/cache_file"
+    require_relative "compact_index_client/parser"
+    require_relative "compact_index_client/updater"
+
+    def initialize(directory, fetcher = nil)
+      @cache = Cache.new(directory, fetcher)
+      @parser = Parser.new(@cache)
+    end
+
+    def names
+      Bundler::CompactIndexClient.debug { "names" }
+      @parser.names
+    end
+
+    def versions
+      Bundler::CompactIndexClient.debug { "versions" }
+      @parser.versions
+    end
+
+    def dependencies(names)
+      Bundler::CompactIndexClient.debug { "dependencies(#{names})" }
+      names.map {|name| info(name) }
+    end
+
+    def info(name)
+      Bundler::CompactIndexClient.debug { "info(#{name})" }
+      @parser.info(name)
+    end
+
+    def latest_version(name)
+      Bundler::CompactIndexClient.debug { "latest_version(#{name})" }
+      @parser.info(name).map {|d| Gem::Version.new(d[INFO_VERSION]) }.max
+    end
+
+    def available?
+      Bundler::CompactIndexClient.debug { "available?" }
+      @parser.available?
+    end
+
+    def reset!
+      Bundler::CompactIndexClient.debug { "reset!" }
+      @cache.reset!
+    end
+  end
+end
diff --git a/lib/bundler/compact_index_client/cache.rb b/lib/bundler/compact_index_client/cache.rb
new file mode 100644
index 0000000000..3bae6c9efd
--- /dev/null
+++ b/lib/bundler/compact_index_client/cache.rb
@@ -0,0 +1,96 @@
+# frozen_string_literal: true
+
+require "rubygems/resolver/api_set/gem_parser"
+
+module Bundler
+  class CompactIndexClient
+    class Cache
+      attr_reader :directory
+
+      def initialize(directory, fetcher = nil)
+        @directory = Pathname.new(directory).expand_path
+        @updater = Updater.new(fetcher) if fetcher
+        @mutex = Thread::Mutex.new
+        @endpoints = Set.new
+
+        @info_root = mkdir("info")
+        @special_characters_info_root = mkdir("info-special-characters")
+        @info_etag_root = mkdir("info-etags")
+      end
+
+      def names
+        fetch("names", names_path, names_etag_path)
+      end
+
+      def versions
+        fetch("versions", versions_path, versions_etag_path)
+      end
+
+      def info(name, remote_checksum = nil)
+        path = info_path(name)
+
+        if remote_checksum && remote_checksum != SharedHelpers.checksum_for_file(path, :MD5)
+          fetch("info/#{name}", path, info_etag_path(name))
+        else
+          Bundler::CompactIndexClient.debug { "update skipped info/#{name} (#{remote_checksum ? "versions index checksum is nil" : "versions index checksum matches local"})" }
+          read(path)
+        end
+      end
+
+      def reset!
+        @mutex.synchronize { @endpoints.clear }
+      end
+
+      private
+
+      def names_path = directory.join("names")
+      def names_etag_path = directory.join("names.etag")
+      def versions_path = directory.join("versions")
+      def versions_etag_path = directory.join("versions.etag")
+
+      def info_path(name)
+        name = name.to_s
+        # TODO: converge this into the info_root by hashing all filenames like info_etag_path
+        if /[^a-z0-9_-]/.match?(name)
+          name += "-#{SharedHelpers.digest(:MD5).hexdigest(name).downcase}"
+          @special_characters_info_root.join(name)
+        else
+          @info_root.join(name)
+        end
+      end
+
+      def info_etag_path(name)
+        name = name.to_s
+        @info_etag_root.join("#{name}-#{SharedHelpers.digest(:MD5).hexdigest(name).downcase}")
+      end
+
+      def mkdir(name)
+        directory.join(name).tap do |dir|
+          SharedHelpers.filesystem_access(dir) do
+            FileUtils.mkdir_p(dir)
+          end
+        end
+      end
+
+      def fetch(remote_path, path, etag_path)
+        if already_fetched?(remote_path)
+          Bundler::CompactIndexClient.debug { "already fetched #{remote_path}" }
+        else
+          Bundler::CompactIndexClient.debug { "fetching #{remote_path}" }
+          @updater&.update(remote_path, path, etag_path)
+        end
+
+        read(path)
+      end
+
+      def already_fetched?(remote_path)
+        @mutex.synchronize { !@endpoints.add?(remote_path) }
+      end
+
+      def read(path)
+        return unless path.file?
+        SharedHelpers.filesystem_access(path, :read, &:read)
+      end
+    end
+  end
+end
diff --git a/lib/bundler/compact_index_client/cache_file.rb b/lib/bundler/compact_index_client/cache_file.rb
new file mode 100644
index 0000000000..299d683438
--- /dev/null
+++ b/lib/bundler/compact_index_client/cache_file.rb
@@ -0,0 +1,148 @@
+# frozen_string_literal: true
+
+require_relative "../vendored_fileutils"
+require "rubygems/package"
+
+module Bundler
+  class CompactIndexClient
+    # write cache files in a way that is robust to concurrent modifications
+    # if digests are given, the checksums will be verified
+    class CacheFile
+      DEFAULT_FILE_MODE = 0o644
+      private_constant :DEFAULT_FILE_MODE
+
+      class Error < RuntimeError; end
+      class ClosedError < Error; end
+
+      class DigestMismatchError < Error
+        def initialize(digests, expected_digests)
+          super "Calculated checksums #{digests.inspect} did not match expected #{expected_digests.inspect}."
+        end
+      end
+
+      # Initialize with a copy of the original file, then yield the instance.
+      def self.copy(path, &block)
+        new(path) do |file|
+          file.initialize_digests
+
+          SharedHelpers.filesystem_access(path, :read) do
+            path.open("rb") do |s|
+              file.open {|f| IO.copy_stream(s, f) }
+            end
+          end
+
+          yield file
+        end
+      end
+
+      # Write data to a temp file, then replace the original file with it verifying the digests if given.
+      def self.write(path, data, digests = nil)
+        return unless data
+        new(path) do |file|
+          file.digests = digests
+          file.write(data)
+        end
+      end
+
+      attr_reader :original_path, :path
+
+      def initialize(original_path, &block)
+        @original_path = original_path
+        @perm = original_path.file? ? original_path.stat.mode : DEFAULT_FILE_MODE
+        @path = original_path.sub(/$/, ".#{$$}.tmp")
+        return unless block_given?
+        begin
+          yield self
+        ensure
+          close
+        end
+      end
+
+      def size
+        path.size
+      end
+
+      # initialize the digests using CompactIndexClient::SUPPORTED_DIGESTS, or a subset based on keys.
+      def initialize_digests(keys = nil)
+        @digests = keys ? SUPPORTED_DIGESTS.slice(*keys) : SUPPORTED_DIGESTS.dup
+        @digests.transform_values! {|algo_class| SharedHelpers.digest(algo_class).new }
+      end
+
+      # reset the digests so they don't contain any previously read data
+      def reset_digests
+        @digests&.each_value(&:reset)
+      end
+
+      # set the digests that will be verified at the end
+      def digests=(expected_digests)
+        @expected_digests = expected_digests
+
+        if @expected_digests.nil?
+          @digests = nil
+        elsif @digests
+          @digests = @digests.slice(*@expected_digests.keys)
+        else
+          initialize_digests(@expected_digests.keys)
+        end
+      end
+
+      def digests?
+        @digests&.any?
+      end
+
+      # Open the temp file for writing, reusing original permissions, yielding the IO object.
+      def open(write_mode = "wb", perm = @perm, &block)
+        raise ClosedError, "Cannot reopen closed file" if @closed
+        SharedHelpers.filesystem_access(path, :write) do
+          path.open(write_mode, perm) do |f|
+            yield digests? ? Gem::Package::DigestIO.new(f, @digests) : f
+          end
+        end
+      end
+
+      # Returns false without appending when no digests since appending is too error prone to do without digests.
+      def append(data)
+        return false unless digests?
+        open("a") {|f| f.write data }
+        verify && commit
+      end
+
+      def write(data)
+        reset_digests
+        open {|f| f.write data }
+        commit!
+      end
+
+      def commit!
+        verify || raise(DigestMismatchError.new(@base64digests, @expected_digests))
+        commit
+      end
+
+      # Verify the digests, returning true on match, false on mismatch.
+      def verify
+        return true unless @expected_digests && digests?
+        @base64digests = @digests.transform_values!(&:base64digest)
+        @digests = nil
+        @base64digests.all? {|algo, digest| @expected_digests[algo] == digest }
+      end
+
+      # Replace the original file with the temp file without verifying digests.
+      # The file is permanently closed.
+      def commit
+        raise ClosedError, "Cannot commit closed file" if @closed
+        SharedHelpers.filesystem_access(original_path, :write) do
+          FileUtils.mv(path, original_path)
+        end
+        @closed = true
+      end
+
+      # Remove the temp file without replacing the original file.
+      # The file is permanently closed.
+      def close
+        return if @closed
+        FileUtils.remove_file(path) if @path&.file?
+        @closed = true
+      end
+    end
+  end
+end
diff --git a/lib/bundler/compact_index_client/parser.rb b/lib/bundler/compact_index_client/parser.rb
new file mode 100644
index 0000000000..ad0d17ed4a
--- /dev/null
+++ b/lib/bundler/compact_index_client/parser.rb
@@ -0,0 +1,87 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CompactIndexClient
+    class Parser
+      # `compact_index` - an object responding to #names, #versions, #info(name, checksum),
+      #                   returning the file contents as a string
+      def initialize(compact_index)
+        @compact_index = compact_index
+        @info_checksums = nil
+        @versions_by_name = nil
+        @available = nil
+        @gem_parser = nil
+      end
+
+      def names
+        lines(@compact_index.names)
+      end
+
+      def versions
+        @versions_by_name ||= Hash.new {|hash, key| hash[key] = [] }
+        @info_checksums = {}
+
+        lines(@compact_index.versions).each do |line|
+          name, versions_string, checksum = line.split(" ", 3)
+          @info_checksums[name] = checksum || ""
+          versions_string.split(",") do |version|
+            delete = version.delete_prefix!("-")
+            version = version.split("-", 2).unshift(name)
+            if delete
+              @versions_by_name[name].delete(version)
+            else
+              @versions_by_name[name] << version
+            end
+          end
+        end
+
+        @versions_by_name
+      end
+
+      def info(name)
+        data = @compact_index.info(name, info_checksums[name])
+        lines(data).map {|line| gem_parser.parse(line).unshift(name) }
+      end
+
+      def available?
+        return @available unless @available.nil?
+        @available = !info_checksums.empty?
+      end
+
+      private
+
+      def info_checksums
+        @info_checksums ||= lines(@compact_index.versions).each_with_object({}) do |line, checksums|
+          parse_version_checksum(line, checksums)
+        end
+      end
+
+      def lines(data)
+        return [] if data.nil? || data.empty?
+        lines = data.split("\n")
+        header = lines.index("---")
+        header ? lines[header + 1..-1] : lines
+      end
+
+      def gem_parser
+        @gem_parser ||= Gem::Resolver::APISet::GemParser.new
+      end
+
+      # This is mostly the same as `split(" ", 3)` but it avoids allocating extra objects.
+      # This method gets called at least once for every gem when parsing versions.
+      def parse_version_checksum(line, checksums)
+        return unless (name_end = line.index(" ")) # Artifactory bug causes blank lines in artifactor index files
+        checksum_start = line.index(" ", name_end + 1)
+        return unless checksum_start
+        checksum_start += 1
+
+        checksum_end = line.size - checksum_start
+
+        line.freeze # allows slicing into the string to not allocate a copy of the line
+        name = line[0, name_end]
+        checksum = line[checksum_start, checksum_end]
+        checksums[name.freeze] = checksum # freeze name since it is used as a hash key
+      end
+    end
+  end
+end
diff --git a/lib/bundler/compact_index_client/updater.rb b/lib/bundler/compact_index_client/updater.rb
new file mode 100644
index 0000000000..6066fdc7c4
--- /dev/null
+++ b/lib/bundler/compact_index_client/updater.rb
@@ -0,0 +1,105 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CompactIndexClient
+    class Updater
+      class MismatchedChecksumError < Error
+        def initialize(path, message)
+          super "The checksum of /#{path} does not match the checksum provided by the server! Something is wrong. #{message}"
+        end
+      end
+
+      def initialize(fetcher)
+        @fetcher = fetcher
+      end
+
+      def update(remote_path, local_path, etag_path)
+        append(remote_path, local_path, etag_path) || replace(remote_path, local_path, etag_path)
+      rescue CacheFile::DigestMismatchError => e
+        raise MismatchedChecksumError.new(remote_path, e.message)
+      rescue Zlib::GzipFile::Error
+        raise Bundler::HTTPError
+      end
+
+      private
+
+      def append(remote_path, local_path, etag_path)
+        return false unless local_path.file? && local_path.size.nonzero?
+
+        CacheFile.copy(local_path) do |file|
+          etag = etag_path.read.tap(&:chomp!) if etag_path.file?
+
+          # Subtract a byte to ensure the range won't be empty.
+          # Avoids 416 (Range Not Satisfiable) responses.
+          response = @fetcher.call(remote_path, request_headers(etag, file.size - 1))
+          break true if response.is_a?(Gem::Net::HTTPNotModified)
+
+          file.digests = parse_digests(response)
+          # server may ignore Range and return the full response
+          if response.is_a?(Gem::Net::HTTPPartialContent)
+            tail = response.body.byteslice(1..-1)
+            break false unless tail && file.append(tail)
+          else
+            file.write(response.body)
+          end
+          CacheFile.write(etag_path, etag_from_response(response))
+          true
+        end
+      end
+
+      # request without range header to get the full file or a 304 Not Modified
+      def replace(remote_path, local_path, etag_path)
+        etag = etag_path.read.tap(&:chomp!) if etag_path.file?
+        response = @fetcher.call(remote_path, request_headers(etag))
+        return true if response.is_a?(Gem::Net::HTTPNotModified)
+        CacheFile.write(local_path, response.body, parse_digests(response))
+        CacheFile.write(etag_path, etag_from_response(response))
+      end
+
+      def request_headers(etag, range_start = nil)
+        headers = {}
+        headers["Range"] = "bytes=#{range_start}-" if range_start
+        headers["If-None-Match"] = %("#{etag}") if etag
+        headers
+      end
+
+      def etag_for_request(etag_path)
+        etag_path.read.tap(&:chomp!) if etag_path.file?
+      end
+
+      def etag_from_response(response)
+        return unless response["ETag"]
+        etag = response["ETag"].delete_prefix("W/")
+        return if etag.delete_prefix!('"') && !etag.delete_suffix!('"')
+        etag
+      end
+
+      # Unwraps and returns a Hash of digest algorithms and base64 values
+      # according to RFC 8941 Structured Field Values for HTTP.
+      # https://www.rfc-editor.org/rfc/rfc8941#name-parsing-a-byte-sequence
+      # Ignores unsupported algorithms.
+      def parse_digests(response)
+        return unless header = response["Repr-Digest"] || response["Digest"]
+        digests = {}
+        header.split(",") do |param|
+          algorithm, value = param.split("=", 2)
+          algorithm.strip!
+          algorithm.downcase!
+          next unless SUPPORTED_DIGESTS.key?(algorithm)
+          next unless value = byte_sequence(value)
+          digests[algorithm] = value
+        end
+        digests.empty? ? nil : digests
+      end
+
+      # Unwrap surrounding colons (byte sequence)
+      # The wrapping characters must be matched or we return nil.
+      # Also handles quotes because right now rubygems.org sends them.
+      def byte_sequence(value)
+        return if value.delete_prefix!(":") && !value.delete_suffix!(":")
+        return if value.delete_prefix!('"') && !value.delete_suffix!('"')
+        value
+      end
+    end
+  end
+end
diff --git a/lib/bundler/constants.rb b/lib/bundler/constants.rb
new file mode 100644
index 0000000000..9564771e78
--- /dev/null
+++ b/lib/bundler/constants.rb
@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+require "rbconfig"
+
+module Bundler
+  WINDOWS = RbConfig::CONFIG["host_os"] =~ /(msdos|mswin|djgpp|mingw)/
+  deprecate_constant :WINDOWS
+
+  FREEBSD = RbConfig::CONFIG["host_os"].to_s.include?("bsd")
+  deprecate_constant :FREEBSD
+
+  NULL = File::NULL
+  deprecate_constant :NULL
+end
diff --git a/lib/bundler/current_ruby.rb b/lib/bundler/current_ruby.rb
new file mode 100644
index 0000000000..17c7655adb
--- /dev/null
+++ b/lib/bundler/current_ruby.rb
@@ -0,0 +1,94 @@
+# frozen_string_literal: true
+
+require_relative "rubygems_ext"
+
+module Bundler
+  # Returns current version of Ruby
+  #
+  # @return [CurrentRuby] Current version of Ruby
+  def self.current_ruby
+    @current_ruby ||= CurrentRuby.new
+  end
+
+  class CurrentRuby
+    ALL_RUBY_VERSIONS = [*18..27, *30..34, *40..41].freeze
+    KNOWN_MINOR_VERSIONS = ALL_RUBY_VERSIONS.map {|v| v.digits.reverse.join(".") }.freeze
+    KNOWN_MAJOR_VERSIONS = ALL_RUBY_VERSIONS.map {|v| v.digits.last.to_s }.uniq.freeze
+    PLATFORM_MAP = {
+      ruby: [Gem::Platform::RUBY, CurrentRuby::ALL_RUBY_VERSIONS],
+      mri: [Gem::Platform::RUBY, CurrentRuby::ALL_RUBY_VERSIONS],
+      rbx: [Gem::Platform::RUBY],
+      truffleruby: [Gem::Platform::RUBY],
+      jruby: [Gem::Platform::JAVA, [18, 19]],
+      windows: [Gem::Platform::WINDOWS, CurrentRuby::ALL_RUBY_VERSIONS],
+      # deprecated
+      mswin: [Gem::Platform::MSWIN, CurrentRuby::ALL_RUBY_VERSIONS],
+      mswin64: [Gem::Platform::MSWIN64, CurrentRuby::ALL_RUBY_VERSIONS - [18]],
+      mingw: [Gem::Platform::UNIVERSAL_MINGW, CurrentRuby::ALL_RUBY_VERSIONS],
+      x64_mingw: [Gem::Platform::UNIVERSAL_MINGW, CurrentRuby::ALL_RUBY_VERSIONS - [18, 19]],
+    }.each_with_object({}) do |(platform, spec), hash|
+      hash[platform] = spec[0]
+      spec[1]&.each {|version| hash[:"#{platform}_#{version}"] = spec[0] }
+    end.freeze
+
+    def ruby?
+      return true if Bundler::MatchPlatform.generic_local_platform_is_ruby?
+
+      !windows? && (RUBY_ENGINE == "ruby" || RUBY_ENGINE == "rbx" || RUBY_ENGINE == "maglev" || RUBY_ENGINE == "truffleruby")
+    end
+
+    def mri?
+      !windows? && RUBY_ENGINE == "ruby"
+    end
+
+    def rbx?
+      ruby? && RUBY_ENGINE == "rbx"
+    end
+
+    def jruby?
+      RUBY_ENGINE == "jruby"
+    end
+
+    def maglev?
+      removed_message =
+        "`CurrentRuby#maglev?` was removed with no replacement. Please use the " \
+        "built-in Ruby `RUBY_ENGINE` constant to check the Ruby implementation you are running on."
+      SharedHelpers.feature_removed!(removed_message)
+    end
+
+    def truffleruby?
+      RUBY_ENGINE == "truffleruby"
+    end
+
+    def windows?
+      Gem.win_platform?
+    end
+    alias_method :mswin?, :windows?
+    alias_method :mswin64?, :windows?
+    alias_method :mingw?, :windows?
+    alias_method :x64_mingw?, :windows?
+
+    (KNOWN_MINOR_VERSIONS + KNOWN_MAJOR_VERSIONS).each do |version|
+      trimmed_version = version.tr(".", "")
+      define_method(:"on_#{trimmed_version}?") do
+        RUBY_VERSION.start_with?("#{version}.")
+      end
+
+      PLATFORM_MAP.keys.each do |platform|
+        define_method(:"#{platform}_#{trimmed_version}?") do
+          send(:"#{platform}?") && send(:"on_#{trimmed_version}?")
+        end
+      end
+
+      define_method(:"maglev_#{trimmed_version}?") do
+        removed_message =
+          "`CurrentRuby##{__method__}` was removed with no replacement. Please use the " \
+          "built-in Ruby `RUBY_ENGINE` and `RUBY_VERSION` constants to perform a similar check."
+
+        SharedHelpers.feature_removed!(removed_message)
+
+        send(:"maglev?") && send(:"on_#{trimmed_version}?")
+      end
+    end
+  end
+end
diff --git a/lib/bundler/definition.rb b/lib/bundler/definition.rb
new file mode 100644
index 0000000000..7a95671471
--- /dev/null
+++ b/lib/bundler/definition.rb
@@ -0,0 +1,1329 @@
+# frozen_string_literal: true
+
+require_relative "lockfile_parser"
+require_relative "worker"
+
+module Bundler
+  class Definition
+    class << self
+      # Do not create or modify a lockfile (Makes #lock a noop)
+      attr_accessor :no_lock
+    end
+
+    attr_writer :lockfile, :overrides
+
+    attr_reader(
+      :dependencies,
+      :locked_checksums,
+      :locked_deps,
+      :locked_gems,
+      :overrides,
+      :platforms,
+      :ruby_version,
+      :lockfile,
+      :gemfiles,
+      :sources
+    )
+
+    # Given a gemfile and lockfile creates a Bundler definition
+    #
+    # @param gemfile [Pathname] Path to Gemfile
+    # @param lockfile [Pathname,nil] Path to Gemfile.lock
+    # @param unlock [Hash, Boolean, nil] Gems that have been requested
+    #   to be updated or true if all gems should be updated
+    # @return [Bundler::Definition]
+    def self.build(gemfile, lockfile, unlock)
+      unlock ||= {}
+      gemfile = Pathname.new(gemfile).expand_path
+
+      raise GemfileNotFound, "#{gemfile} not found" unless gemfile.file?
+
+      Plugin.hook(Plugin::Events::GEM_BEFORE_EVAL, gemfile, lockfile)
+      Dsl.evaluate(gemfile, lockfile, unlock).tap do |definition|
+        Plugin.hook(Plugin::Events::GEM_AFTER_EVAL, definition)
+      end
+    end
+
+    #
+    # How does the new system work?
+    #
+    # * Load information from Gemfile and Lockfile
+    # * Invalidate stale locked specs
+    #  * All specs from stale source are stale
+    #  * All specs that are reachable only through a stale
+    #    dependency are stale.
+    # * If all fresh dependencies are satisfied by the locked
+    #  specs, then we can try to resolve locally.
+    #
+    # @param lockfile [Pathname] Path to Gemfile.lock
+    # @param dependencies [Array(Bundler::Dependency)] array of dependencies from Gemfile
+    # @param sources [Bundler::SourceList]
+    # @param unlock [Hash, Boolean, nil] Gems that have been requested
+    #   to be updated or true if all gems should be updated
+    # @param ruby_version [Bundler::RubyVersion, nil] Requested Ruby Version
+    # @param optional_groups [Array(String)] A list of optional groups
+    def initialize(lockfile, dependencies, sources, unlock, ruby_version = nil, optional_groups = [], gemfiles = [], overrides = [])
+      unlock ||= {}
+
+      if unlock == true
+        @unlocking_all = true
+        strict = false
+        @unlocking_bundler = false
+        @unlocking = unlock
+        @sources_to_unlock = []
+        @unlocking_ruby = false
+        @explicit_unlocks = []
+        conservative = false
+      else
+        @unlocking_all = false
+        strict = unlock.delete(:strict)
+        @unlocking_bundler = unlock.delete(:bundler)
+        @unlocking = unlock.any? {|_k, v| !Array(v).empty? }
+        @sources_to_unlock = unlock.delete(:sources) || []
+        @unlocking_ruby = unlock.delete(:ruby)
+        @explicit_unlocks = unlock.delete(:gems) || []
+        conservative = unlock.delete(:conservative)
+      end
+
+      @dependencies    = dependencies
+      @sources         = sources
+      @optional_groups = optional_groups
+      @prefer_local    = false
+      @specs           = nil
+      @ruby_version    = ruby_version
+      @gemfiles        = gemfiles
+      @overrides       = overrides
+
+      @lockfile               = lockfile
+      @lockfile_contents      = String.new
+
+      @locked_bundler_version = nil
+      @resolved_bundler_version = nil
+
+      @locked_ruby_version = nil
+      @new_platforms = []
+      @removed_platforms = []
+      @originally_invalid_platforms = []
+
+      if lockfile_exists?
+        @lockfile_contents = Bundler.read_file(lockfile)
+        @locked_gems = LockfileParser.new(@lockfile_contents, strict: strict)
+        @locked_platforms = @locked_gems.platforms
+        @most_specific_locked_platform = @locked_gems.most_specific_locked_platform
+        @platforms = @locked_platforms.dup
+        @locked_bundler_version = @locked_gems.bundler_version
+        @locked_ruby_version = @locked_gems.ruby_version
+        @locked_deps = @locked_gems.dependencies
+        Override.attach(@locked_gems.specs, @overrides)
+        @originally_locked_specs = SpecSet.new(@locked_gems.specs)
+        @originally_locked_sources = @locked_gems.sources
+        @locked_checksums = @locked_gems.checksums
+
+        if @unlocking_all
+          @locked_specs   = SpecSet.new([])
+          @locked_sources = []
+        else
+          @locked_specs   = @originally_locked_specs
+          @locked_sources = @originally_locked_sources
+        end
+
+        locked_gem_sources = @originally_locked_sources.select {|s| s.is_a?(Source::Rubygems) }
+        multisource_lockfile = locked_gem_sources.size == 1 && locked_gem_sources.first.multiple_remotes?
+
+        if multisource_lockfile
+          msg = "Your lockfile contains a single rubygems source section with multiple remotes, which is insecure. Make sure you run `bundle install` in non frozen mode and commit the result to make your lockfile secure."
+
+          Bundler::SharedHelpers.feature_removed! msg
+        end
+      else
+        @locked_gems = nil
+        @locked_platforms = []
+        @most_specific_locked_platform = nil
+        @platforms      = []
+        @locked_deps    = {}
+        @locked_specs   = SpecSet.new([])
+        @locked_sources = []
+        @originally_locked_specs = @locked_specs
+        @originally_locked_sources = @locked_sources
+        @locked_checksums = Bundler.settings[:lockfile_checksums]
+      end
+
+      @unlocking_ruby ||= if @ruby_version && locked_ruby_version_object
+        @ruby_version.diff(locked_ruby_version_object)
+      end
+      @unlocking ||= @unlocking_ruby ||= (!@locked_ruby_version ^ !@ruby_version)
+
+      @current_platform_missing = add_current_platform unless Bundler.frozen_bundle?
+
+      @source_changes = converge_sources
+      @path_changes = converge_paths
+
+      if conservative
+        @gems_to_unlock = @explicit_unlocks.any? ? @explicit_unlocks : @dependencies.map(&:name)
+      else
+        eager_unlock = @explicit_unlocks.map {|name| Dependency.new(name, ">= 0") }
+        @gems_to_unlock = @locked_specs.for(eager_unlock, platforms).map(&:name).uniq
+      end
+
+      @dependency_changes = converge_dependencies
+      @local_changes = converge_locals
+
+      check_lockfile
+    end
+
+    def gem_version_promoter
+      @gem_version_promoter ||= GemVersionPromoter.new
+    end
+
+    def check!
+      # If dependencies have changed, we need to resolve remotely. Otherwise,
+      # since we'll be resolving with a single local source, we may end up
+      # locking gems under the wrong source in the lockfile, and missing lockfile
+      # checksums
+      resolve_remotely! if @dependency_changes
+
+      # Now do a local only resolve, to verify if any gems are missing locally
+      sources.local_only!
+      resolve
+    end
+
+    #
+    # Setup sources according to the given options and the state of the
+    # definition.
+    #
+    # @return [Boolean] Whether fetching remote information will be necessary or not
+    #
+    def setup_domain!(options = {})
+      prefer_local! if options[:"prefer-local"]
+
+      sources.cached!
+
+      if options[:add_checksums] || (!options[:local] && install_needed?)
+        sources.remote!
+        true
+      else
+        Bundler.settings.set_command_option(:jobs, 1) unless install_needed? # to avoid the overhead of Bundler::Worker
+        sources.local!
+        false
+      end
+    end
+
+    def resolve_with_cache!
+      with_cache!
+
+      resolve
+    end
+
+    def with_cache!
+      sources.local!
+      sources.cached!
+    end
+
+    def resolve_remotely!
+      remotely!
+
+      resolve
+    end
+
+    def remotely!
+      sources.cached!
+      sources.remote!
+    end
+
+    def prefer_local!
+      @prefer_local = true
+
+      sources.prefer_local!
+    end
+
+    # For given dependency list returns a SpecSet with Gemspec of all the required
+    # dependencies.
+    #  1. The method first resolves the dependencies specified in Gemfile
+    #  2. After that it tries and fetches gemspec of resolved dependencies
+    #
+    # @return [Bundler::SpecSet]
+    def specs
+      @specs ||= materialize(requested_dependencies)
+    end
+
+    def new_specs
+      specs - @locked_specs
+    end
+
+    def removed_specs
+      @locked_specs - specs
+    end
+
+    def missing_specs
+      preload_git_sources
+      resolve.missing_specs_for(requested_dependencies)
+    end
+
+    def missing_specs?
+      missing = missing_specs
+      return false if missing.empty?
+      Bundler.ui.debug "The definition is missing #{missing.map(&:full_name)}"
+      true
+    rescue BundlerError => e
+      @resolve = nil
+      @resolver = nil
+      @resolution_base = nil
+      @source_requirements = nil
+      @specs = nil
+
+      Bundler.ui.debug "The definition is missing dependencies, failed to resolve & materialize locally (#{e})"
+      true
+    end
+
+    def requested_specs
+      specs_for(requested_groups)
+    end
+
+    def requested_dependencies
+      dependencies_for(requested_groups)
+    end
+
+    def current_dependencies
+      filter_relevant(dependencies)
+    end
+
+    def current_locked_dependencies
+      filter_relevant(locked_dependencies)
+    end
+
+    def filter_relevant(dependencies)
+      dependencies.select do |d|
+        relevant_deps?(d)
+      end
+    end
+
+    def relevant_deps?(dep)
+      platforms_array = [Bundler.generic_local_platform].freeze
+
+      dep.should_include? && !dep.gem_platforms(platforms_array).empty?
+    end
+
+    def locked_dependencies
+      @locked_deps.values
+    end
+
+    def new_deps
+      @new_deps ||= @dependencies - locked_dependencies
+    end
+
+    def deleted_deps
+      @deleted_deps ||= locked_dependencies - @dependencies
+    end
+
+    def specs_for(groups)
+      return specs if groups.empty?
+      deps = dependencies_for(groups)
+      materialize(deps)
+    end
+
+    def dependencies_for(groups)
+      groups.map!(&:to_sym)
+      deps = current_dependencies # always returns a new array
+      deps.select! do |d|
+        d.groups.intersect?(groups)
+      end
+      deps
+    end
+
+    # Resolve all the dependencies specified in Gemfile. It ensures that
+    # dependencies that have been already resolved via locked file and are fresh
+    # are reused when resolving dependencies
+    #
+    # @return [SpecSet] resolved dependencies
+    def resolve
+      @resolve ||= if Bundler.frozen_bundle?
+        Bundler.ui.debug "Frozen, using resolution from the lockfile"
+        @locked_specs
+      elsif no_resolve_needed?
+        if deleted_deps.any?
+          Bundler.ui.debug "Some dependencies were deleted, using a subset of the resolution from the lockfile"
+          SpecSet.new(filter_specs(@locked_specs, @dependencies - deleted_deps))
+        else
+          Bundler.ui.debug "Found no changes, using resolution from the lockfile"
+          if @removed_platforms.any? || @locked_gems.may_include_redundant_platform_specific_gems?
+            SpecSet.new(filter_specs(@locked_specs, @dependencies))
+          else
+            @locked_specs
+          end
+        end
+      else
+        Bundler.ui.debug resolve_needed_reason
+
+        start_resolution
+      end
+    end
+
+    def spec_git_paths
+      sources.git_sources.filter_map {|s| File.realpath(s.path) if File.exist?(s.path) }
+    end
+
+    def groups
+      dependencies.flat_map(&:groups).uniq
+    end
+
+    def lock(file_or_preserve_unknown_sections = false, preserve_unknown_sections_or_unused = false)
+      if [true, false, nil].include?(file_or_preserve_unknown_sections)
+        target_lockfile = lockfile
+        preserve_unknown_sections = file_or_preserve_unknown_sections
+      else
+        target_lockfile = file_or_preserve_unknown_sections
+        preserve_unknown_sections = preserve_unknown_sections_or_unused
+
+        suggestion = if target_lockfile == lockfile
+          "To fix this warning, remove it from the `Definition#lock` call."
+        else
+          "Instead, instantiate a new definition passing `#{target_lockfile}`, and call `lock` without a file argument on that definition"
+        end
+
+        msg = "`Definition#lock` was passed a target file argument. #{suggestion}"
+
+        Bundler::SharedHelpers.feature_removed! msg
+      end
+
+      write_lock(target_lockfile, preserve_unknown_sections)
+    end
+
+    def write_lock(file, preserve_unknown_sections)
+      return if Definition.no_lock || !lockfile || file.nil?
+
+      contents = to_lock
+
+      # Convert to \r\n if the existing lock has them
+      # i.e., Windows with `git config core.autocrlf=true`
+      contents.gsub!(/\n/, "\r\n") if @lockfile_contents.match?("\r\n")
+
+      if @locked_bundler_version
+        locked_major = @locked_bundler_version.segments.first
+        current_major = bundler_version_to_lock.segments.first
+
+        updating_major = locked_major < current_major
+      end
+
+      preserve_unknown_sections ||= !updating_major && (Bundler.frozen_bundle? || !(unlocking? || @unlocking_bundler))
+
+      if File.exist?(file) && lockfiles_equal?(@lockfile_contents, contents, preserve_unknown_sections)
+        return if Bundler.frozen_bundle?
+        SharedHelpers.filesystem_access(file) { FileUtils.touch(file) }
+        return
+      end
+
+      if Bundler.frozen_bundle?
+        Bundler.ui.error "Cannot write a changed lockfile while frozen."
+        return
+      end
+
+      begin
+        SharedHelpers.filesystem_access(file) do |p|
+          File.open(p, "wb") {|f| f.puts(contents) }
+        end
+      rescue ReadOnlyFileSystemError
+        raise ProductionError, lockfile_changes_summary("file system is read-only")
+      end
+    end
+
+    def locked_ruby_version
+      return unless ruby_version
+      if @unlocking_ruby || !@locked_ruby_version
+        Bundler::RubyVersion.system
+      else
+        @locked_ruby_version
+      end
+    end
+
+    def locked_ruby_version_object
+      return unless @locked_ruby_version
+      @locked_ruby_version_object ||= begin
+        unless version = RubyVersion.from_string(@locked_ruby_version)
+          raise LockfileError, "The Ruby version #{@locked_ruby_version} from " \
+            "#{@lockfile} could not be parsed. " \
+            "Try running bundle update --ruby to resolve this."
+        end
+        version
+      end
+    end
+
+    def bundler_version_to_lock
+      @resolved_bundler_version || Bundler.gem_version
+    end
+
+    def to_lock
+      require_relative "lockfile_generator"
+      LockfileGenerator.generate(self)
+    end
+
+    def ensure_equivalent_gemfile_and_lockfile(explicit_flag = false)
+      return unless Bundler.frozen_bundle?
+
+      raise ProductionError, "Frozen mode is set, but there's no lockfile" unless lockfile_exists?
+
+      msg = lockfile_changes_summary("frozen mode is set")
+      return unless msg
+
+      unless explicit_flag
+        suggested_command = unless Bundler.settings.locations("frozen").keys.include?(:env)
+          "bundle config set frozen false"
+        end
+        msg << "\n\nIf this is a development machine, remove the #{SharedHelpers.relative_lockfile_path} " \
+               "freeze by running `#{suggested_command}`." if suggested_command
+      end
+
+      raise ProductionError, msg
+    end
+
+    def validate_runtime!
+      validate_ruby!
+      validate_platforms!
+    end
+
+    def validate_ruby!
+      return unless ruby_version
+
+      if diff = ruby_version.diff(Bundler::RubyVersion.system)
+        problem, expected, actual = diff
+
+        msg = case problem
+              when :engine
+                "Your Ruby engine is #{actual}, but your Gemfile specified #{expected}"
+              when :version
+                "Your Ruby version is #{actual}, but your Gemfile specified #{expected}"
+              when :engine_version
+                "Your #{Bundler::RubyVersion.system.engine} version is #{actual}, but your Gemfile specified #{ruby_version.engine} #{expected}"
+        end
+
+        raise RubyVersionMismatch, msg
+      end
+    end
+
+    def validate_platforms!
+      return if current_platform_locked? || @platforms.include?(Gem::Platform::RUBY)
+
+      raise ProductionError, "Your bundle only supports platforms #{@platforms.map(&:to_s)} " \
+        "but your local platform is #{Bundler.local_platform}. " \
+        "Add the current platform to the lockfile with\n`bundle lock --add-platform #{Bundler.local_platform}` and try again."
+    end
+
+    def normalize_platforms
+      resolve.normalize_platforms!(current_dependencies, platforms)
+
+      @resolve = SpecSet.new(resolve.for(current_dependencies, @platforms))
+    end
+
+    def add_platform(platform)
+      return if @platforms.include?(platform)
+
+      @new_platforms << platform
+      @platforms << platform
+    end
+
+    def remove_platform(platform)
+      raise InvalidOption, "Unable to remove the platform `#{platform}` since the only platforms are #{@platforms.join ", "}" unless @platforms.include?(platform)
+
+      @removed_platforms << platform
+      @platforms.delete(platform)
+    end
+
+    def nothing_changed?
+      !something_changed?
+    end
+
+    def no_resolve_needed?
+      !resolve_needed?
+    end
+
+    def unlocking?
+      @unlocking
+    end
+
+    def add_checksums
+      require "rubygems/package"
+
+      @locked_checksums = true
+
+      setup_domain!(add_checksums: true)
+
+      # force materialization to real specifications, so that checksums are fetched
+      specs.each do |spec|
+        next unless spec.source.is_a?(Bundler::Source::Rubygems)
+        # Checksum was fetched from the compact index API.
+        next if !spec.source.checksum_store.missing?(spec) && !spec.source.checksum_store.empty?(spec)
+        # The gem isn't installed, can't compute the checksum.
+        next unless spec.loaded_from
+
+        package = Gem::Package.new(spec.source.cached_built_in_gem(spec))
+        checksum = Checksum.from_gem_package(package)
+        spec.source.checksum_store.register(spec, checksum)
+      end
+    end
+
+    private
+
+    def lockfile_changes_summary(update_refused_reason)
+      added =   []
+      deleted = []
+      changed = []
+
+      added.concat @new_platforms.map {|p| "* platform: #{p}" }
+      deleted.concat @removed_platforms.map {|p| "* platform: #{p}" }
+
+      added.concat new_deps.map {|d| "* #{pretty_dep(d)}" } if new_deps.any?
+      deleted.concat deleted_deps.map {|d| "* #{pretty_dep(d)}" } if deleted_deps.any?
+
+      both_sources = Hash.new {|h, k| h[k] = [] }
+      current_dependencies.each {|d| both_sources[d.name][0] = d }
+      current_locked_dependencies.each {|d| both_sources[d.name][1] = d }
+
+      both_sources.each do |name, (dep, lock_dep)|
+        next if dep.nil? || lock_dep.nil?
+
+        gemfile_source = dep.source || default_source
+        lock_source = lock_dep.source || default_source
+        next if lock_source.include?(gemfile_source)
+
+        gemfile_source_name = dep.source ? gemfile_source.to_gemfile : "no specified source"
+        lockfile_source_name = lock_dep.source ? lock_source.to_gemfile : "no specified source"
+        changed << "* #{name} from `#{lockfile_source_name}` to `#{gemfile_source_name}`"
+      end
+
+      return unless added.any? || deleted.any? || changed.any? || resolve_needed?
+
+      msg = String.new("#{change_reason[0].upcase}#{change_reason[1..-1].strip}, but ")
+      msg << "the lockfile " unless msg.start_with?("Your lockfile")
+      msg << "can't be updated because #{update_refused_reason}"
+      msg << "\n\nYou have added to the Gemfile:\n" << added.join("\n") if added.any?
+      msg << "\n\nYou have deleted from the Gemfile:\n" << deleted.join("\n") if deleted.any?
+      msg << "\n\nYou have changed in the Gemfile:\n" << changed.join("\n") if changed.any?
+      msg << "\n\nRun `bundle install` elsewhere and add the updated #{SharedHelpers.relative_lockfile_path} to version control.\n" unless unlocking?
+      msg
+    end
+
+    def install_needed?
+      resolve_needed? || missing_specs?
+    end
+
+    def something_changed?
+      return true unless lockfile_exists?
+
+      @source_changes ||
+        @dependency_changes ||
+        @current_platform_missing ||
+        @new_platforms.any? ||
+        @path_changes ||
+        @local_changes ||
+        @missing_lockfile_dep ||
+        @unlocking_bundler ||
+        @locked_spec_with_missing_checksums ||
+        @locked_spec_with_empty_checksums ||
+        @locked_spec_with_missing_deps ||
+        @locked_spec_with_invalid_deps
+    end
+
+    def resolve_needed?
+      unlocking? || something_changed?
+    end
+
+    def should_add_extra_platforms?
+      !lockfile_exists? && Bundler::MatchPlatform.generic_local_platform_is_ruby? && !Bundler.settings[:force_ruby_platform]
+    end
+
+    def lockfile_exists?
+      lockfile && File.exist?(lockfile)
+    end
+
+    def resolver
+      @resolver ||= new_resolver(resolution_base)
+    end
+
+    def expanded_dependencies
+      apply_overrides_to(dependencies_with_bundler) + metadata_dependencies
+    end
+
+    def apply_overrides_to(deps)
+      return deps if @overrides.empty?
+      deps.map {|dep| apply_override_to(dep) }
+    end
+
+    def apply_override_to(dep)
+      override = Override.find_for(@overrides, dep.name, :version)
+      return dep unless override
+      new_dep = dep.dup
+      new_dep.instance_variable_set(:@requirement, override.apply_to(dep.requirement))
+      new_dep
+    end
+
+    def dependencies_with_bundler
+      return dependencies unless @unlocking_bundler
+      return dependencies if dependencies.any? {|d| d.name == "bundler" }
+
+      [Dependency.new("bundler", @unlocking_bundler)] + dependencies
+    end
+
+    def resolution_base
+      @resolution_base ||= begin
+        last_resolve = converge_locked_specs
+        remove_invalid_platforms!
+        base = new_resolution_base(last_resolve: last_resolve, unlock: @unlocking_all || @gems_to_unlock)
+        base = additional_base_requirements_to_prevent_downgrades(base)
+        base = additional_base_requirements_to_force_updates(base)
+        base
+      end
+    end
+
+    def filter_specs(specs, deps, skips: [])
+      SpecSet.new(specs).for(deps, platforms, skips: skips)
+    end
+
+    def materialize(dependencies)
+      specs = begin
+        resolve.materialize(dependencies)
+      rescue IncorrectLockfileDependencies => e
+        raise if Bundler.frozen_bundle?
+
+        reresolve_without([e.spec])
+        retry
+      end
+
+      missing_specs = resolve.missing_specs
+
+      if missing_specs.any?
+        missing_specs.each do |s|
+          locked_gem = @locked_specs[s.name].last
+          next if locked_gem.nil? || locked_gem.version != s.version || sources.local_mode?
+
+          message = if sources.implicit_global_source?
+            "Because your Gemfile specifies no global remote source, your bundle is locked to " \
+            "#{locked_gem} from #{locked_gem.source}. However, #{locked_gem} is not installed. You'll " \
+            "need to either add a global remote source to your Gemfile or make sure #{locked_gem} is " \
+            "available locally before rerunning Bundler."
+          else
+            "Your bundle is locked to #{locked_gem} from #{locked_gem.source}, but that version can " \
+            "no longer be found in that source. That means the author of #{locked_gem} has removed it. " \
+            "You'll need to update your bundle to a version other than #{locked_gem} that hasn't been " \
+            "removed in order to install."
+          end
+
+          raise GemNotFound, message
+        end
+
+        missing_specs_list = missing_specs.group_by(&:source).map do |source, missing_specs_for_source|
+          "#{missing_specs_for_source.map(&:full_name).join(", ")} in #{source}"
+        end
+
+        raise GemNotFound, "Could not find #{missing_specs_list.join(" nor ")}"
+      end
+
+      partially_missing_specs = resolve.partially_missing_specs
+
+      if partially_missing_specs.any? && !sources.local_mode?
+        Bundler.ui.warn "Some locked specs have possibly been yanked (#{partially_missing_specs.map(&:full_name).join(", ")}). Ignoring them..."
+
+        resolve.delete(partially_missing_specs)
+      end
+
+      incomplete_specs = resolve.incomplete_specs
+      loop do
+        break if incomplete_specs.empty?
+
+        Bundler.ui.debug("The lockfile does not have all gems needed for the current platform though, Bundler will still re-resolve dependencies")
+        sources.remote!
+        reresolve_without(incomplete_specs)
+        specs = resolve.materialize(dependencies)
+
+        still_incomplete_specs = resolve.incomplete_specs
+
+        if still_incomplete_specs == incomplete_specs
+          resolver.raise_incomplete! incomplete_specs
+        end
+
+        incomplete_specs = still_incomplete_specs
+      end
+
+      insecurely_materialized_specs = resolve.insecurely_materialized_specs
+
+      if insecurely_materialized_specs.any?
+        Bundler.ui.warn "The following platform specific gems are getting installed, yet the lockfile includes only their generic ruby version:\n" \
+                        " * #{insecurely_materialized_specs.map(&:full_name).join("\n * ")}\n" \
+                        "Please run `bundle lock --normalize-platforms` and commit the resulting lockfile.\n" \
+                        "Alternatively, you may run `bundle lock --add-platform <list-of-platforms-that-you-want-to-support>`"
+      end
+
+      bundler = sources.metadata_source.specs.search(["bundler", Bundler.gem_version]).last
+      specs["bundler"] = bundler
+
+      specs
+    end
+
+    def reresolve_without(incomplete_specs)
+      resolution_base.delete(incomplete_specs)
+      @resolve = start_resolution
+    end
+
+    def start_resolution
+      local_platform_needed_for_resolvability = @most_specific_non_local_locked_platform && !@platforms.include?(Bundler.local_platform)
+      @platforms << Bundler.local_platform if local_platform_needed_for_resolvability
+
+      result = SpecSet.new(resolver.start)
+
+      @resolved_bundler_version = result.find {|spec| spec.name == "bundler" }&.version
+
+      @new_platforms.each do |platform|
+        incomplete_specs = result.incomplete_specs_for_platform(current_dependencies, platform)
+
+        if incomplete_specs.any?
+          resolver.raise_incomplete! incomplete_specs
+        end
+      end
+
+      if @most_specific_non_local_locked_platform
+        if result.incomplete_for_platform?(current_dependencies, @most_specific_non_local_locked_platform)
+          @platforms.delete(@most_specific_non_local_locked_platform)
+        elsif local_platform_needed_for_resolvability
+          @platforms.delete(Bundler.local_platform)
+        end
+      end
+
+      if should_add_extra_platforms?
+        result.add_extra_platforms!(platforms)
+      elsif @originally_invalid_platforms.any?
+        result.add_originally_invalid_platforms!(platforms, @originally_invalid_platforms)
+      end
+
+      SpecSet.new(result.for(dependencies, @platforms | [Gem::Platform::RUBY]))
+    end
+
+    def precompute_source_requirements_for_indirect_dependencies?
+      if sources.non_global_rubygems_sources.all?(&:dependency_api_available?)
+        true
+      else
+        non_dependency_api_warning
+        false
+      end
+    end
+
+    def non_dependency_api_warning
+      non_api_sources = sources.non_global_rubygems_sources.reject(&:dependency_api_available?)
+      non_api_source_names = non_api_sources.map {|d| "  * #{d}" }.join("\n")
+
+      msg = String.new
+      msg << "Your Gemfile contains scoped sources that don't implement a dependency API, namely:\n\n"
+      msg << non_api_source_names
+      msg << "\n\nUsing the above gem servers may result in installing unexpected gems. " \
+        "To resolve this warning, make sure you use gem servers that implement dependency APIs, " \
+        "such as gemstash or geminabox gem servers."
+      Bundler.ui.warn msg
+    end
+
+    def current_platform_locked?
+      @platforms.any? do |bundle_platform|
+        Bundler.generic_local_platform == bundle_platform || Bundler.local_platform === bundle_platform
+      end
+    end
+
+    def add_current_platform
+      return if @platforms.include?(Bundler.local_platform)
+
+      @most_specific_non_local_locked_platform = find_most_specific_locked_platform
+      return if @most_specific_non_local_locked_platform
+
+      @platforms << Bundler.local_platform
+      true
+    end
+
+    def find_most_specific_locked_platform
+      return unless current_platform_locked?
+
+      @most_specific_locked_platform
+    end
+
+    def resolve_needed_reason
+      if lockfile_exists?
+        if unlocking?
+          "Re-resolving dependencies because #{unlocking_reason}"
+        else
+          "Found changes from the lockfile, re-resolving dependencies because #{lockfile_changed_reason}"
+        end
+      else
+        "Resolving dependencies because there's no lockfile"
+      end
+    end
+
+    def change_reason
+      if resolve_needed?
+        if unlocking?
+          unlocking_reason
+        else
+          lockfile_changed_reason
+        end
+      else
+        "some dependencies were deleted from your gemfile"
+      end
+    end
+
+    def unlocking_reason
+      unlock_targets = if @gems_to_unlock.any?
+        ["gems", @gems_to_unlock]
+      elsif @sources_to_unlock.any?
+        ["sources", @sources_to_unlock]
+      end
+
+      unlock_reason = if unlock_targets
+        "#{unlock_targets.first}: (#{unlock_targets.last.join(", ")})"
+      else
+        @unlocking_ruby ? "ruby" : ""
+      end
+
+      "bundler is unlocking #{unlock_reason}"
+    end
+
+    def lockfile_changed_reason
+      [
+        [@source_changes, "the list of sources changed"],
+        [@dependency_changes, "the dependencies in your gemfile changed"],
+        [@current_platform_missing, "your lockfile is missing the current platform"],
+        [@new_platforms.any?, "you are adding a new platform to your lockfile"],
+        [@path_changes, "the gemspecs for path gems changed"],
+        [@local_changes, "the gemspecs for git local gems changed"],
+        [@missing_lockfile_dep, "your lockfile is missing \"#{@missing_lockfile_dep}\""],
+        [@unlocking_bundler, "an update to the version of Bundler itself was requested"],
+        [@locked_spec_with_missing_checksums, "your lockfile is missing a CHECKSUMS entry for \"#{@locked_spec_with_missing_checksums}\""],
+        [@locked_spec_with_empty_checksums, "your lockfile has an empty CHECKSUMS entry for \"#{@locked_spec_with_empty_checksums}\""],
+        [@locked_spec_with_missing_deps, "your lockfile includes \"#{@locked_spec_with_missing_deps}\" but not some of its dependencies"],
+        [@locked_spec_with_invalid_deps, "your lockfile does not satisfy dependencies of \"#{@locked_spec_with_invalid_deps}\""],
+      ].select(&:first).map(&:last).join(", ")
+    end
+
+    def pretty_dep(dep)
+      SharedHelpers.pretty_dependency(dep)
+    end
+
+    # Check if the specs of the given source changed
+    # according to the locked source.
+    def specs_changed?(source)
+      locked = @locked_sources.find {|s| s == source }
+
+      !locked || dependencies_for_source_changed?(source, locked) || specs_for_source_changed?(source)
+    end
+
+    def dependencies_for_source_changed?(source, locked_source)
+      deps_for_source = @dependencies.select {|dep| dep.source == source }
+      locked_deps_for_source = locked_dependencies.select {|dep| dep.source == locked_source }
+
+      deps_for_source.uniq.sort != locked_deps_for_source.sort
+    end
+
+    def specs_for_source_changed?(source)
+      locked_index = Index.new
+      locked_index.use(@locked_specs.select {|s| s.replace_source_with!(source) })
+
+      !locked_index.subset?(source.specs)
+    rescue PathError, GitError => e
+      Bundler.ui.debug "Assuming that #{source} has not changed since fetching its specs errored (#{e})"
+      false
+    end
+
+    # Get all locals and override their matching sources.
+    # Return true if any of the locals changed (for example,
+    # they point to a new revision) or depend on new specs.
+    def converge_locals
+      locals = []
+
+      Bundler.settings.local_overrides.map do |k, v|
+        spec   = @dependencies.find {|s| s.name == k }
+        source = spec&.source
+        if source&.respond_to?(:local_override!)
+          source.unlock! if @gems_to_unlock.include?(spec.name)
+          locals << [source, source.local_override!(v)]
+        end
+      end
+
+      sources_with_changes = locals.select do |source, changed|
+        changed || specs_changed?(source)
+      end.map(&:first)
+      !sources_with_changes.each {|source| @sources_to_unlock << source.name }.empty?
+    end
+
+    def check_lockfile
+      @locked_spec_with_invalid_deps = nil
+      @locked_spec_with_missing_deps = nil
+      @locked_spec_with_missing_checksums = nil
+      @locked_spec_with_empty_checksums = nil
+
+      missing_deps = []
+      missing_checksums = []
+      empty_checksums = []
+      invalid = []
+
+      @locked_specs.each do |s|
+        if @locked_checksums
+          checksum_store = s.source.checksum_store
+
+          if checksum_store.missing?(s)
+            missing_checksums << s
+          elsif checksum_store.empty?(s)
+            empty_checksums << s
+          end
+        end
+
+        validation = @locked_specs.validate_deps(s)
+
+        missing_deps << s if validation == :missing
+        invalid << s if validation == :invalid
+      end
+
+      @locked_spec_with_missing_checksums = missing_checksums.first.name if missing_checksums.any?
+      @locked_spec_with_empty_checksums = empty_checksums.first.name if empty_checksums.any?
+
+      if missing_deps.any?
+        @locked_specs.delete(missing_deps)
+
+        @locked_spec_with_missing_deps = missing_deps.first.name
+      end
+
+      if invalid.any?
+        @locked_specs.delete(invalid)
+
+        @locked_spec_with_invalid_deps = invalid.first.name
+      end
+    end
+
+    def converge_paths
+      sources.path_sources.any? do |source|
+        specs_changed?(source)
+      end
+    end
+
+    def converge_sources
+      # Replace the sources from the Gemfile with the sources from the Gemfile.lock,
+      # if they exist in the Gemfile.lock and are `==`. If you can't find an equivalent
+      # source in the Gemfile.lock, use the one from the Gemfile.
+      changes = sources.replace_sources!(@locked_sources)
+
+      sources.all_sources.each do |source|
+        # has to be done separately, because we want to keep the locked checksum
+        # store for a source, even when doing a full update
+        if @locked_checksums && @locked_gems && locked_source = @originally_locked_sources.find {|s| s == source && !s.equal?(source) }
+          source.checksum_store.merge!(locked_source.checksum_store)
+        end
+        # If the source is unlockable and the current command allows an unlock of
+        # the source (for example, you are doing a `bundle update <foo>` of a git-pinned
+        # gem), unlock it. For git sources, this means to unlock the revision, which
+        # will cause the `ref` used to be the most recent for the branch (or master) if
+        # an explicit `ref` is not used.
+        if source.respond_to?(:unlock!) && @sources_to_unlock.include?(source.name)
+          source.unlock!
+          changes = true
+        end
+      end
+
+      sources.metadata_source.checksum_store.merge!(@locked_gems.metadata_source.checksum_store) if @locked_gems
+
+      changes
+    end
+
+    def converge_dependencies
+      @missing_lockfile_dep = nil
+      @changed_dependencies = []
+
+      @dependencies.each do |dep|
+        if dep.source
+          dep.source = sources.get(dep.source)
+        end
+        next unless relevant_deps?(dep)
+
+        name = dep.name
+
+        dep_changed = @locked_deps[name].nil?
+
+        unless name == "bundler"
+          locked_specs = @originally_locked_specs[name]
+
+          if locked_specs.empty?
+            @missing_lockfile_dep = name if dep_changed == false
+          else
+            if locked_specs.map(&:source).uniq.size > 1
+              @locked_specs.delete(locked_specs.select {|s| s.source != dep.source })
+            end
+
+            unless apply_override_to(dep).matches_spec?(locked_specs.first)
+              @gems_to_unlock << name
+              dep_changed = true
+            end
+          end
+        end
+
+        @changed_dependencies << name if dep_changed
+      end
+
+      converge_overrides_outside_dependencies
+
+      @changed_dependencies.any?
+    end
+
+    def converge_overrides_outside_dependencies
+      @overrides.each do |override|
+        # :all overrides are intentionally not pre-unlocked. They take effect on
+        # fresh resolution (no lockfile) or when the user runs `bundle update`.
+        # Forcing a full re-resolve from a single :all directive would surprise
+        # users with unrelated dependency churn.
+        next unless override.target.is_a?(String)
+
+        name = override.target
+        next if @changed_dependencies.include?(name)
+        next if @originally_locked_specs[name].empty?
+        # version: overrides on direct deps are detected in the per-dep
+        # converge_dependencies loop via apply_override_to + matches_spec?.
+        # Other fields are not visible there, so they always reach here.
+        next if override.field == :version && @dependencies.any? {|d| d.name == name }
+
+        @gems_to_unlock << name
+        @changed_dependencies << name
+      end
+    end
+
+    # Remove elements from the locked specs that are expired. This will most
+    # commonly happen if the Gemfile has changed since the lockfile was last
+    # generated
+    def converge_locked_specs
+      converged = converge_specs(@locked_specs)
+
+      resolve = SpecSet.new(converged)
+
+      diff = nil
+
+      # Now, we unlock any sources that do not have anymore gems pinned to it
+      sources.all_sources.each do |source|
+        next unless source.respond_to?(:unlock!)
+
+        unless resolve.any? {|s| s.source == source }
+          diff ||= @locked_specs.to_a - resolve.to_a
+          source.unlock! if diff.any? {|s| s.source == source }
+        end
+      end
+
+      resolve
+    end
+
+    def converge_specs(specs)
+      converged = []
+      deps = []
+
+      specs.each do |s|
+        name = s.name
+        next if @gems_to_unlock.include?(name)
+
+        dep = @dependencies.find {|d| s.satisfies?(d) }
+        lockfile_source = s.source
+
+        if dep
+          replacement_source = dep.source
+
+          deps << dep if !replacement_source || lockfile_source.include?(replacement_source) || new_deps.include?(dep)
+        else
+          parent_dep = @dependencies.find do |d|
+            next unless d.source && d.source != lockfile_source
+            next if d.source.is_a?(Source::Gemspec)
+
+            parent_locked_specs = @originally_locked_specs[d.name]
+
+            parent_locked_specs.any? do |parent_spec|
+              parent_spec.runtime_dependencies.any? {|rd| rd.name == s.name }
+            end
+          end
+
+          if parent_dep && parent_dep.source.is_a?(Source::Path) && parent_dep.source.specs[s]&.any?
+            replacement_source = parent_dep.source
+          else
+            replacement_source = sources.get(lockfile_source)
+          end
+        end
+
+        # Replace the locked dependency's source with the equivalent source from the Gemfile
+        s.source = replacement_source || default_source
+        next if s.source_changed?
+
+        source = s.source
+        next if @sources_to_unlock.include?(source.name)
+
+        # Path sources have special logic
+        if source.is_a?(Source::Path)
+          new_spec = source.specs[s].first
+          if new_spec
+            s.runtime_dependencies.replace(new_spec.runtime_dependencies)
+          else
+            # If the spec is no longer in the path source, unlock it. This
+            # commonly happens if the version changed in the gemspec
+            @gems_to_unlock << name
+          end
+        end
+
+        converged << s
+      end
+
+      filter_specs(converged, deps, skips: @gems_to_unlock)
+    end
+
+    def metadata_dependencies
+      @metadata_dependencies ||= [
+        Dependency.new("Ruby\0", Bundler::RubyVersion.system.gem_version),
+        Dependency.new("RubyGems\0", Gem::VERSION),
+      ]
+    end
+
+    def source_requirements
+      @source_requirements ||= find_source_requirements
+    end
+
+    def preload_git_source_worker
+      workers = Bundler.settings.installation_parallelization
+
+      @preload_git_source_worker ||= Bundler::Worker.new(workers, "Git source preloading", ->(source, _) { source.specs })
+    end
+
+    def preload_git_sources
+      if Gem.ruby_version < Gem::Version.new("3.3")
+        # Ruby 3.2 has a bug that incorrectly triggers a circular dependency warning. This version will continue to
+        # fetch git repositories one by one.
+        return
+      end
+
+      begin
+        needed_git_sources.each {|source| preload_git_source_worker.enq(source) }
+      ensure
+        preload_git_source_worker.stop
+      end
+    end
+
+    # Git sources needed for the requested groups (excludes sources only used by --without groups)
+    def needed_git_sources
+      needed_deps = dependencies_for(requested_groups)
+      sources.git_sources.select do |source|
+        needed_deps.any? {|d| d.source == source }
+      end
+    end
+
+    # Git sources that should be excluded (only used by --without groups)
+    def excluded_git_sources
+      sources.git_sources - needed_git_sources
+    end
+
+    def find_source_requirements
+      preload_git_sources
+
+      # Only safe to exclude when locked_requirements (merged below) backfills the gap.
+      nothing_changed = nothing_changed?
+      excluded = nothing_changed ? excluded_git_sources : []
+
+      # Record the specs available in each gem's source, so that those
+      # specs will be available later when the resolver knows where to
+      # look for that gemspec (or its dependencies)
+      source_requirements = if precompute_source_requirements_for_indirect_dependencies?
+        all_requirements = source_map.all_requirements(excluded)
+        { default: default_source }.merge(all_requirements)
+      else
+        { default: Source::RubygemsAggregate.new(sources, source_map, excluded) }.merge(source_map.direct_requirements)
+      end
+      source_requirements.merge!(source_map.locked_requirements) if nothing_changed
+      metadata_dependencies.each do |dep|
+        source_requirements[dep.name] = sources.metadata_source
+      end
+
+      default_bundler_source = source_requirements["bundler"] || default_source
+
+      if @unlocking_bundler
+        default_bundler_source.add_dependency_names("bundler")
+      else
+        source_requirements[:default_bundler] = default_bundler_source
+        source_requirements["bundler"] = sources.metadata_source # needs to come last to override
+      end
+
+      source_requirements
+    end
+
+    def default_source
+      sources.default_source
+    end
+
+    def requested_groups
+      values = groups - Bundler.settings[:without] - @optional_groups + Bundler.settings[:with]
+      values &= Bundler.settings[:only] unless Bundler.settings[:only].empty?
+      values
+    end
+
+    def lockfiles_equal?(current, proposed, preserve_unknown_sections)
+      if preserve_unknown_sections
+        sections_to_ignore = LockfileParser.sections_to_ignore(@locked_bundler_version)
+        sections_to_ignore += LockfileParser.unknown_sections_in_lockfile(current)
+        sections_to_ignore << LockfileParser::RUBY
+        sections_to_ignore << LockfileParser::BUNDLED unless @unlocking_bundler
+        pattern = /#{Regexp.union(sections_to_ignore)}\n(\s{2,}.*\n)+/
+        whitespace_cleanup = /\n{2,}/
+        current = current.gsub(pattern, "\n").gsub(whitespace_cleanup, "\n\n").strip
+        proposed = proposed.gsub(pattern, "\n").gsub(whitespace_cleanup, "\n\n").strip
+      end
+      current == proposed
+    end
+
+    def additional_base_requirements_to_prevent_downgrades(resolution_base)
+      return resolution_base unless @locked_gems
+      @originally_locked_specs.each do |locked_spec|
+        next if locked_spec.source.is_a?(Source::Path) || locked_spec.source_changed?
+
+        name = locked_spec.name
+        next if @changed_dependencies.include?(name)
+
+        resolution_base.base_requirements[name] = Gem::Requirement.new(">= #{locked_spec.version}")
+      end
+      resolution_base
+    end
+
+    def additional_base_requirements_to_force_updates(resolution_base)
+      return resolution_base if @explicit_unlocks.empty?
+      full_update = SpecSet.new(new_resolver_for_full_update.start)
+      @explicit_unlocks.each do |name|
+        version = full_update.version_for(name)
+        resolution_base.base_requirements[name] = Gem::Requirement.new("= #{version}") if version
+      end
+      resolution_base
+    end
+
+    def remove_invalid_platforms!
+      return if Bundler.frozen_bundle?
+
+      skips = (@new_platforms + [Bundler.local_platform]).uniq
+
+      # We should probably avoid removing non-ruby platforms, since that means
+      # lockfile will no longer install on those platforms, so a error to give
+      # heads up to the user may be better. However, we have tests expecting
+      # non ruby platform autoremoval to work, so leaving that in place for
+      # now.
+      skips |= platforms - [Gem::Platform::RUBY] if @dependency_changes
+
+      @originally_invalid_platforms = @originally_locked_specs.remove_invalid_platforms!(current_dependencies, platforms, skips: skips)
+    end
+
+    def source_map
+      @source_map ||= SourceMap.new(sources, dependencies, @locked_specs)
+    end
+
+    def new_resolver_for_full_update
+      new_resolver(unlocked_resolution_base)
+    end
+
+    def unlocked_resolution_base
+      new_resolution_base(last_resolve: SpecSet.new([]), unlock: true)
+    end
+
+    def new_resolution_base(last_resolve:, unlock:)
+      new_resolution_platforms = @current_platform_missing ? @new_platforms + [Bundler.local_platform] : @new_platforms
+      Resolver::Base.new(source_requirements, expanded_dependencies, last_resolve, @platforms, locked_specs: @originally_locked_specs, unlock: unlock, prerelease: gem_version_promoter.pre?, prefer_local: @prefer_local, new_platforms: new_resolution_platforms, overrides: @overrides)
+    end
+
+    def new_resolver(base)
+      Resolver.new(base, gem_version_promoter, @most_specific_locked_platform)
+    end
+  end
+end
diff --git a/lib/bundler/dependency.rb b/lib/bundler/dependency.rb
new file mode 100644
index 0000000000..cb9c7a76ea
--- /dev/null
+++ b/lib/bundler/dependency.rb
@@ -0,0 +1,151 @@
+# frozen_string_literal: true
+
+require "rubygems/dependency"
+require_relative "shared_helpers"
+
+module Bundler
+  class Dependency < Gem::Dependency
+    def initialize(name, version, options = {}, &blk)
+      type = options["type"] || :runtime
+      super(name, version, type)
+
+      @options = options
+    end
+
+    def groups
+      @groups ||= Array(@options["group"] || :default).map(&:to_sym)
+    end
+
+    def source
+      return @source if defined?(@source)
+
+      @source = @options["source"]
+    end
+
+    def path
+      return @path if defined?(@path)
+
+      @path = @options["path"]
+    end
+
+    def git
+      return @git if defined?(@git)
+
+      @git = @options["git"]
+    end
+
+    def github
+      return @github if defined?(@github)
+
+      @github = @options["github"]
+    end
+
+    def branch
+      return @branch if defined?(@branch)
+
+      @branch = @options["branch"]
+    end
+
+    def ref
+      return @ref if defined?(@ref)
+
+      @ref = @options["ref"]
+    end
+
+    def glob
+      return @glob if defined?(@glob)
+
+      @glob = @options["glob"]
+    end
+
+    def platforms
+      @platforms ||= Array(@options["platforms"])
+    end
+
+    def env
+      return @env if defined?(@env)
+
+      @env = @options["env"]
+    end
+
+    def should_include
+      @should_include ||= @options.fetch("should_include", true)
+    end
+
+    def gemfile
+      return @gemfile if defined?(@gemfile)
+
+      @gemfile = @options["gemfile"]
+    end
+
+    def force_ruby_platform
+      return @force_ruby_platform if defined?(@force_ruby_platform)
+
+      @force_ruby_platform = @options["force_ruby_platform"]
+    end
+
+    def autorequire
+      return @autorequire if defined?(@autorequire)
+
+      @autorequire = Array(@options["require"] || []) if @options.key?("require")
+    end
+
+    RUBY_PLATFORM_ARRAY = [Gem::Platform::RUBY].freeze
+    private_constant :RUBY_PLATFORM_ARRAY
+
+    # Returns the platforms this dependency is valid for, in the same order as
+    # passed in the `valid_platforms` parameter
+    def gem_platforms(valid_platforms)
+      return RUBY_PLATFORM_ARRAY if force_ruby_platform
+      return valid_platforms if platforms.empty?
+
+      valid_platforms.select {|p| expanded_platforms.include?(Gem::Platform.generic(p)) }
+    end
+
+    def expanded_platforms
+      @expanded_platforms ||= platforms.filter_map {|pl| CurrentRuby::PLATFORM_MAP[pl] }.flatten.uniq
+    end
+
+    def should_include?
+      should_include && current_env? && current_platform?
+    end
+
+    def gemspec_dev_dep?
+      @gemspec_dev_dep ||= @options.fetch("gemspec_dev_dep", false)
+    end
+
+    def gemfile_dep?
+      !gemspec_dev_dep?
+    end
+
+    def current_env?
+      return true unless env
+      if env.is_a?(Hash)
+        env.all? do |key, val|
+          ENV[key.to_s] && (val.is_a?(String) ? ENV[key.to_s] == val : ENV[key.to_s] =~ val)
+        end
+      else
+        ENV[env.to_s]
+      end
+    end
+
+    def current_platform?
+      return true if platforms.empty?
+      platforms.any? do |p|
+        Bundler.current_ruby.send("#{p}?")
+      end
+    end
+
+    def to_lock
+      out = super
+      out << "!" if source
+      out
+    end
+
+    def specific?
+      super
+    rescue NoMethodError
+      requirement != ">= 0"
+    end
+  end
+end
diff --git a/lib/bundler/deployment.rb b/lib/bundler/deployment.rb
new file mode 100644
index 0000000000..3344449e82
--- /dev/null
+++ b/lib/bundler/deployment.rb
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+require_relative "shared_helpers"
+Bundler::SharedHelpers.feature_removed! "Bundler no longer integrates with " \
+  "Capistrano, but Capistrano provides its own integration with " \
+  "Bundler via the capistrano-bundler gem. Use it instead."
diff --git a/lib/bundler/deprecate.rb b/lib/bundler/deprecate.rb
new file mode 100644
index 0000000000..f59533630e
--- /dev/null
+++ b/lib/bundler/deprecate.rb
@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+begin
+  require "rubygems/deprecate"
+rescue LoadError
+  # it's fine if it doesn't exist on the current RubyGems...
+  nil
+end
+
+module Bundler
+  # If Bundler::Deprecate is an autoload constant, we need to define it
+  if defined?(Bundler::Deprecate) && !autoload?(:Deprecate)
+    # nothing to do!
+  elsif defined? ::Deprecate
+    Deprecate = ::Deprecate
+  elsif defined? Gem::Deprecate
+    Deprecate = Gem::Deprecate
+  else
+    class Deprecate
+    end
+  end
+
+  unless Deprecate.respond_to?(:skip_during)
+    def Deprecate.skip_during
+      original = skip
+      self.skip = true
+      yield
+    ensure
+      self.skip = original
+    end
+  end
+
+  unless Deprecate.respond_to?(:skip)
+    def Deprecate.skip
+      @skip ||= false
+    end
+  end
+
+  unless Deprecate.respond_to?(:skip=)
+    def Deprecate.skip=(skip)
+      @skip = skip
+    end
+  end
+end
diff --git a/lib/bundler/digest.rb b/lib/bundler/digest.rb
new file mode 100644
index 0000000000..158803033d
--- /dev/null
+++ b/lib/bundler/digest.rb
@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+# This code was extracted from https://github.com/Solistra/ruby-digest which is under public domain
+module Bundler
+  module Digest
+    # The initial constant values for the 32-bit constant words A, B, C, D, and
+    # E, respectively.
+    SHA1_WORDS = [0x67452301, 0xEFCDAB89, 0x98BADCFE, 0x10325476, 0xC3D2E1F0].freeze
+
+    # The 8-bit field used for bitwise `AND` masking. Defaults to `0xFFFFFFFF`.
+    SHA1_MASK = 0xFFFFFFFF
+
+    class << self
+      def sha1(string)
+        unless string.is_a?(String)
+          raise TypeError, "can't convert #{string.class.inspect} into String"
+        end
+
+        buffer = string.b
+
+        words = SHA1_WORDS.dup
+        generate_split_buffer(buffer) do |chunk|
+          w = []
+          chunk.each_slice(4) do |a, b, c, d|
+            w << (((a << 8 | b) << 8 | c) << 8 | d)
+          end
+          a, b, c, d, e = *words
+          (16..79).each do |i|
+            w[i] = SHA1_MASK & rotate(w[i - 3] ^ w[i - 8] ^ w[i - 14] ^ w[i - 16], 1)
+          end
+          0.upto(79) do |i|
+            case i
+            when  0..19
+              f = ((b & c) | (~b & d))
+              k = 0x5A827999
+            when 20..39
+              f = (b ^ c ^ d)
+              k = 0x6ED9EBA1
+            when 40..59
+              f = ((b & c) | (b & d) | (c & d))
+              k = 0x8F1BBCDC
+            when 60..79
+              f = (b ^ c ^ d)
+              k = 0xCA62C1D6
+            end
+            t = SHA1_MASK & rotate(a, 5) + f + e + k + w[i]
+            a, b, c, d, e = t, a, SHA1_MASK & rotate(b, 30), c, d # rubocop:disable Style/ParallelAssignment
+          end
+          mutated = [a, b, c, d, e]
+          words.map!.with_index {|word, index| SHA1_MASK & (word + mutated[index]) }
+        end
+
+        words.pack("N*").unpack1("H*")
+      end
+
+      private
+
+      def generate_split_buffer(string, &block)
+        size   = string.bytesize * 8
+        buffer = string.bytes << 128
+        buffer << 0 while buffer.size % 64 != 56
+        buffer.concat([size].pack("Q>").bytes)
+        buffer.each_slice(64, &block)
+      end
+
+      def rotate(value, spaces)
+        value << spaces | value >> (32 - spaces)
+      end
+    end
+  end
+end
diff --git a/lib/bundler/dsl.rb b/lib/bundler/dsl.rb
new file mode 100644
index 0000000000..6e2638a8be
--- /dev/null
+++ b/lib/bundler/dsl.rb
@@ -0,0 +1,698 @@
+# frozen_string_literal: true
+
+require_relative "dependency"
+require_relative "ruby_dsl"
+
+module Bundler
+  class Dsl
+    include RubyDsl
+
+    def self.evaluate(gemfile, lockfile, unlock)
+      builder = new
+      builder.lockfile(lockfile)
+      builder.eval_gemfile(gemfile)
+      builder.to_definition(builder.lockfile_path, unlock)
+    end
+
+    VALID_PLATFORMS = Bundler::CurrentRuby::PLATFORM_MAP.keys.freeze
+
+    VALID_KEYS = %w[group groups git path glob name branch ref tag require submodules
+                    platform platforms source install_if force_ruby_platform].freeze
+
+    GITHUB_PULL_REQUEST_URL = %r{\Ahttps://github\.com/([A-Za-z0-9_\-\.]+/[A-Za-z0-9_\-\.]+)/pull/(\d+)\z}
+    GITLAB_MERGE_REQUEST_URL = %r{\Ahttps://gitlab\.com/([A-Za-z0-9_\-\./]+)/-/merge_requests/(\d+)\z}
+
+    attr_reader :gemspecs, :gemfile, :overrides
+    attr_accessor :dependencies
+
+    def initialize
+      @source               = nil
+      @sources              = SourceList.new
+      @git_sources          = {}
+      @dependencies         = []
+      @groups               = []
+      @install_conditionals = []
+      @optional_groups      = []
+      @platforms            = []
+      @env                  = nil
+      @ruby_version         = nil
+      @gemspecs             = []
+      @gemfile              = nil
+      @gemfiles             = []
+      @lockfile             = nil
+      @overrides            = []
+      add_git_sources
+    end
+
+    def eval_gemfile(gemfile, contents = nil)
+      with_gemfile(gemfile) do |current_gemfile|
+        contents ||= Bundler.read_file(current_gemfile)
+        instance_eval(contents, current_gemfile, 1)
+      rescue GemfileEvalError => e
+        message = "There was an error evaluating `#{File.basename current_gemfile}`: #{e.message}"
+        raise DSLError.new(message, current_gemfile, e.backtrace, contents)
+      rescue GemfileError, InvalidArgumentError, InvalidOption, DeprecatedError, ScriptError => e
+        message = "There was an error parsing `#{File.basename current_gemfile}`: #{e.message}"
+        raise DSLError.new(message, current_gemfile, e.backtrace, contents)
+      rescue StandardError => e
+        raise unless e.backtrace_locations.first.path == current_gemfile
+        message = "There was an error parsing `#{File.basename current_gemfile}`: #{e.message}"
+        raise DSLError.new(message, current_gemfile, e.backtrace, contents)
+      end
+    end
+
+    def gemspec(opts = nil)
+      opts ||= {}
+      path              = opts[:path] || "."
+      glob              = opts[:glob]
+      name              = opts[:name]
+      development_group = opts[:development_group] || :development
+      expanded_path     = gemfile_root.join(path)
+
+      gemspecs = Gem::Util.glob_files_in_dir("{,*}.gemspec", expanded_path).filter_map {|g| Bundler.load_gemspec(g) }
+      gemspecs.reject! {|s| s.name != name } if name
+      specs_by_name_and_version = gemspecs.group_by {|s| [s.name, s.version] }
+
+      case specs_by_name_and_version.size
+      when 1
+        specs = specs_by_name_and_version.values.first
+        spec = specs.find {|s| s.installable_on_platform?(Bundler.local_platform) } || specs.first
+
+        @gemspecs << spec
+
+        path path, "glob" => glob, "name" => spec.name, "gemspec" => spec do
+          add_dependency spec.name
+        end
+
+        spec.development_dependencies.each do |dep|
+          add_dependency dep.name, dep.requirement.as_list, "gemspec_dev_dep" => true, "group" => development_group
+        end
+      when 0
+        raise InvalidOption, "There are no gemspecs at #{expanded_path}"
+      else
+        raise InvalidOption, "There are multiple gemspecs at #{expanded_path}. " \
+          "Please use the :name option to specify which one should be used"
+      end
+    end
+
+    def gem(name, *args)
+      options = args.last.is_a?(Hash) ? args.pop.dup : {}
+      version = args || [">= 0"]
+
+      normalize_options(name, version, options)
+
+      add_dependency(name, version, options)
+    end
+
+    # For usage in Dsl.evaluate, since lockfile is used as part of the Gemfile.
+    def lockfile_path
+      @lockfile
+    end
+
+    def lockfile(file)
+      @lockfile = file
+    end
+
+    def source(source, *args, &blk)
+      options = args.last.is_a?(Hash) ? args.pop.dup : {}
+      options = normalize_hash(options)
+      source = normalize_source(source)
+      cooldown = options["cooldown"]
+      if cooldown && !(cooldown.is_a?(Integer) && cooldown >= 0)
+        raise InvalidOption, "Expected `cooldown` to be a non-negative integer, got #{cooldown.inspect}"
+      end
+
+      if options.key?("type")
+        options["type"] = options["type"].to_s
+        unless Plugin.source?(options["type"])
+          raise InvalidOption, "No plugin sources available for #{options["type"]}"
+        end
+
+        unless block_given?
+          raise InvalidOption, "You need to pass a block to #source with :type option"
+        end
+
+        source_opts = options.merge("uri" => source)
+        with_source(@sources.add_plugin_source(options["type"], source_opts), &blk)
+      elsif block_given?
+        with_source(@sources.add_rubygems_source("remotes" => source, "cooldown" => cooldown), &blk)
+      else
+        @sources.add_global_rubygems_remote(source, cooldown: cooldown)
+      end
+    end
+
+    def git_source(name, &block)
+      unless block_given?
+        raise InvalidOption, "You need to pass a block to #git_source"
+      end
+
+      if valid_keys.include?(name.to_s)
+        raise InvalidOption, "You cannot use #{name} as a git source. It " \
+          "is a reserved key. Reserved keys are: #{valid_keys.join(", ")}"
+      end
+
+      @git_sources[name.to_s] = block
+    end
+
+    def path(path, options = {}, &blk)
+      source_options = normalize_hash(options).merge(
+        "path" => Pathname.new(path),
+        "root_path" => gemfile_root
+      )
+
+      source_options["global"] = true unless block_given?
+
+      source = @sources.add_path_source(source_options)
+      with_source(source, &blk)
+    end
+
+    def git(uri, options = {}, &blk)
+      unless block_given?
+        msg = "You can no longer specify a git source by itself. Instead, \n" \
+              "either use the :git option on a gem, or specify the gems that \n" \
+              "bundler should find in the git source by passing a block to \n" \
+              "the git method, like: \n\n" \
+              "  git 'git://github.com/rails/rails.git' do\n" \
+              "    gem 'rails'\n" \
+              "  end"
+        raise DeprecatedError, msg
+      end
+
+      with_source(@sources.add_git_source(normalize_hash(options).merge("uri" => uri)), &blk)
+    end
+
+    def github(repo, options = {})
+      raise InvalidArgumentError, "GitHub sources require a block" unless block_given?
+      github_uri  = @git_sources["github"].call(repo)
+      git_options = normalize_hash(options).merge("uri" => github_uri)
+      git_source  = @sources.add_git_source(git_options)
+      with_source(git_source) { yield }
+    end
+
+    SUPPORTED_OVERRIDE_FIELDS = [:version, :required_ruby_version, :required_rubygems_version].freeze
+    SUPPORTED_OVERRIDE_SYMBOL_OPERATIONS = [:ignore_upper].freeze
+
+    def override(target, **operations)
+      validate_override_target!(target)
+
+      if target == :all && operations.key?(:version)
+        raise ArgumentError, "`override :all, version:` is not allowed; version requirements are per-gem"
+      end
+
+      operations.each do |field, operation|
+        validate_override_field!(field)
+        validate_override_operation!(operation)
+        validate_override_uniqueness!(target, field)
+      end
+
+      source_location = caller_locations(1, 1)&.first
+      operations.each do |field, operation|
+        @overrides << Override.new(target, field, operation, source_location: source_location)
+      end
+    end
+
+    def to_definition(lockfile, unlock)
+      check_primary_source_safety
+      lockfile = @lockfile unless @lockfile.nil?
+      Definition.new(lockfile, @dependencies, @sources, unlock, @ruby_version, @optional_groups, @gemfiles, @overrides)
+    end
+
+    def group(*args, &blk)
+      options = args.last.is_a?(Hash) ? args.pop.dup : {}
+      normalize_group_options(options, args)
+
+      @groups.concat args
+
+      if options["optional"]
+        optional_groups = args - @optional_groups
+        @optional_groups.concat optional_groups
+      end
+
+      yield
+    ensure
+      args.each { @groups.pop }
+    end
+
+    def install_if(*args)
+      @install_conditionals.concat args
+      yield
+    ensure
+      args.each { @install_conditionals.pop }
+    end
+
+    def platforms(*platforms)
+      @platforms.concat platforms
+      yield
+    ensure
+      platforms.each { @platforms.pop }
+    end
+    alias_method :platform, :platforms
+
+    def env(name)
+      old = @env
+      @env = name
+      yield
+    ensure
+      @env = old
+    end
+
+    def plugin(*args)
+      # Pass on
+    end
+
+    def method_missing(name, *args)
+      raise GemfileError, "Undefined local variable or method `#{name}' for Gemfile"
+    end
+
+    def check_primary_source_safety
+      check_path_source_safety
+      check_rubygems_source_safety
+    end
+
+    private
+
+    def validate_override_target!(target)
+      return if target == :all
+      return if target.is_a?(String)
+      raise ArgumentError, "override target must be :all or a gem name string, got #{target.inspect}"
+    end
+
+    def validate_override_field!(field)
+      return if SUPPORTED_OVERRIDE_FIELDS.include?(field)
+      supported = SUPPORTED_OVERRIDE_FIELDS.map {|f| "`#{f}:`" }.join(", ")
+      raise ArgumentError, "unsupported override field `#{field}:`; supported fields: #{supported}"
+    end
+
+    def validate_override_operation!(operation)
+      case operation
+      when String
+        Gem::Requirement.new(operation)
+      when nil
+        # ok
+      when Symbol
+        return if SUPPORTED_OVERRIDE_SYMBOL_OPERATIONS.include?(operation)
+        raise ArgumentError, "unsupported override operation: #{operation.inspect}"
+      else
+        raise ArgumentError, "override operation must be a String, Symbol, or nil, got #{operation.inspect}"
+      end
+    rescue Gem::Requirement::BadRequirementError => e
+      raise ArgumentError, "invalid override version requirement #{operation.inspect}: #{e.message}"
+    end
+
+    def validate_override_uniqueness!(target, field)
+      return unless @overrides.any? {|o| o.target == target && o.field == field }
+      raise ArgumentError, "duplicate override for #{target.inspect} `#{field}:`"
+    end
+
+    def add_dependency(name, version = nil, options = {})
+      options["gemfile"] = @gemfile
+      options["source"] ||= @source
+      options["env"] ||= @env
+
+      dep = Dependency.new(name, version, options)
+
+      # if there's already a dependency with this name we try to prefer one
+      if current = @dependencies.find {|d| d.name == name }
+        if current.requirement != dep.requirement
+          current_requirement_open = current.requirements_list.include?(">= 0")
+
+          gemspec_dep = [dep, current].find(&:gemspec_dev_dep?)
+          if gemspec_dep
+            require_relative "vendor/pub_grub/lib/pub_grub/version_range"
+            require_relative "vendor/pub_grub/lib/pub_grub/version_constraint"
+            require_relative "vendor/pub_grub/lib/pub_grub/version_union"
+            require_relative "vendor/pub_grub/lib/pub_grub/rubygems"
+
+            current_gemspec_range = PubGrub::RubyGems.requirement_to_range(current.requirement)
+            next_gemspec_range = PubGrub::RubyGems.requirement_to_range(dep.requirement)
+
+            if current_gemspec_range.intersects?(next_gemspec_range)
+              dep = Dependency.new(name, current.requirement.as_list + dep.requirement.as_list, options)
+            else
+              gemfile_dep = [dep, current].find(&:gemfile_dep?)
+
+              if gemfile_dep
+                raise GemfileError, "The #{name} dependency has conflicting requirements in Gemfile (#{gemfile_dep.requirement}) and gemspec (#{gemspec_dep.requirement})"
+              else
+                raise GemfileError, "Two gemspec development dependencies have conflicting requirements on the same gem: #{dep} and #{current}"
+              end
+            end
+          else
+            update_prompt = ""
+
+            if File.basename(@gemfile) == Injector::INJECTED_GEMS
+              if dep.requirements_list.include?(">= 0") && !current_requirement_open
+                update_prompt = ". Gem already added"
+              else
+                update_prompt = ". If you want to update the gem version, run `bundle update #{name}`"
+
+                update_prompt += ". You may also need to change the version requirement specified in the Gemfile if it's too restrictive." unless current_requirement_open
+              end
+            end
+
+            raise GemfileError, "You cannot specify the same gem twice with different version requirements.\n" \
+                           "You specified: #{name} (#{current.requirement}) and #{name} (#{dep.requirement})" \
+                           "#{update_prompt}"
+          end
+        end
+
+        unless current.gemspec_dev_dep? && dep.gemspec_dev_dep?
+          # Always prefer the dependency from the Gemfile
+          if current.gemspec_dev_dep?
+            @dependencies.delete(current)
+          elsif dep.gemspec_dev_dep?
+            return
+          elsif current.source.to_s != dep.source.to_s
+            raise GemfileError, "You cannot specify the same gem twice coming from different sources.\n" \
+                            "You specified that #{name} (#{dep.requirement}) should come from " \
+                            "#{current.source || "an unspecified source"} and #{dep.source}\n"
+          else
+            Bundler.ui.warn "Your Gemfile lists the gem #{name} (#{current.requirement}) more than once.\n" \
+                            "You should probably keep only one of them.\n" \
+                            "Remove any duplicate entries and specify the gem only once.\n" \
+                            "While it's not a problem now, it could cause errors if you change the version of one of them later."
+          end
+        end
+      end
+
+      @dependencies << dep
+    end
+
+    def with_gemfile(gemfile)
+      expanded_gemfile_path = Pathname.new(gemfile).expand_path(@gemfile&.parent)
+      original_gemfile = @gemfile
+      @gemfile = expanded_gemfile_path
+      @gemfiles << expanded_gemfile_path
+      yield @gemfile.to_s
+    ensure
+      @gemfile = original_gemfile
+    end
+
+    def add_git_sources
+      git_source(:github) do |repo_name|
+        if repo_name =~ GITHUB_PULL_REQUEST_URL
+          {
+            "git" => "https://github.com/#{$1}.git",
+            "branch" => nil,
+            "ref" => "refs/pull/#{$2}/head",
+            "tag" => nil,
+          }
+        else
+          repo_name = "#{repo_name}/#{repo_name}" unless repo_name.include?("/")
+          "https://github.com/#{repo_name}.git"
+        end
+      end
+
+      git_source(:gist) do |repo_name|
+        "https://gist.github.com/#{repo_name}.git"
+      end
+
+      git_source(:bitbucket) do |repo_name|
+        user_name, repo_name = repo_name.split("/")
+        repo_name ||= user_name
+        "https://#{user_name}@bitbucket.org/#{user_name}/#{repo_name}.git"
+      end
+
+      git_source(:gitlab) do |repo_name|
+        if repo_name =~ GITLAB_MERGE_REQUEST_URL
+          {
+            "git" => "https://gitlab.com/#{$1}.git",
+            "branch" => nil,
+            "ref" => "refs/merge-requests/#{$2}/head",
+            "tag" => nil,
+          }
+        else
+          repo_name = "#{repo_name}/#{repo_name}" unless repo_name.include?("/")
+          "https://gitlab.com/#{repo_name}.git"
+        end
+      end
+    end
+
+    def with_source(source)
+      old_source = @source
+      if block_given?
+        @source = source
+        yield
+      end
+      source
+    ensure
+      @source = old_source
+    end
+
+    def normalize_hash(opts)
+      opts.keys.each do |k|
+        opts[k.to_s] = opts.delete(k) unless k.is_a?(String)
+      end
+      opts
+    end
+
+    def valid_keys
+      @valid_keys ||= VALID_KEYS
+    end
+
+    def normalize_options(name, version, opts)
+      if name.is_a?(Symbol)
+        raise GemfileError, %(You need to specify gem names as Strings. Use 'gem "#{name}"' instead)
+      end
+      if /\s/.match?(name)
+        raise GemfileError, %('#{name}' is not a valid gem name because it contains whitespace)
+      end
+      raise GemfileError, %(an empty gem name is not valid) if name.empty?
+
+      normalize_hash(opts)
+
+      git_names = @git_sources.keys.map(&:to_s)
+      validate_keys("gem '#{name}'", opts, valid_keys + git_names)
+
+      groups = @groups.dup
+      opts["group"] = opts.delete("groups") || opts["group"]
+      groups.concat Array(opts.delete("group"))
+      groups = [:default] if groups.empty?
+
+      install_if = @install_conditionals.dup
+      install_if.concat Array(opts.delete("install_if"))
+      install_if = install_if.reduce(true) do |memo, val|
+        memo && (val.respond_to?(:call) ? val.call : val)
+      end
+
+      platforms = @platforms.dup
+      opts["platforms"] = opts["platform"] || opts["platforms"]
+      platforms.concat Array(opts.delete("platforms"))
+      platforms.map!(&:to_sym)
+      platforms.each do |p|
+        next if VALID_PLATFORMS.include?(p)
+        raise GemfileError, "`#{p}` is not a valid platform. The available options are: #{VALID_PLATFORMS.inspect}"
+      end
+
+      windows_platforms = platforms.select {|pl| pl.to_s.match?(/mingw|mswin/) }
+      if windows_platforms.any?
+        windows_platforms = windows_platforms.map! {|pl| ":#{pl}" }.join(", ")
+        deprecated_message = "Platform #{windows_platforms} will be removed in the future. Please use platform :windows instead."
+        Bundler::SharedHelpers.feature_deprecated! deprecated_message
+      end
+
+      # Save sources passed in a key
+      if opts.key?("source")
+        source = normalize_source(opts["source"])
+        opts["source"] = @sources.add_rubygems_source("remotes" => source)
+      end
+
+      git_name = (git_names & opts.keys).last
+      if @git_sources[git_name]
+        git_opts = @git_sources[git_name].call(opts[git_name])
+        git_opts = { "git" => git_opts } if git_opts.is_a?(String)
+        opts.merge!(git_opts) do |key, _gemfile_value, _git_source_value|
+          raise GemfileError, %(The :#{key} option can't be used with `#{git_name}: #{opts[git_name].inspect}`)
+        end
+      end
+
+      %w[git path].each do |type|
+        next unless param = opts[type]
+        if version.first && version.first =~ /^\s*=?\s*(\d[^\s]*)\s*$/
+          options = opts.merge("name" => name, "version" => $1)
+        else
+          options = opts.dup
+        end
+        source = send(type, param, options) {}
+        opts["source"] = source
+      end
+
+      opts["platforms"]      = platforms.dup
+      opts["group"]          = groups
+      opts["should_include"] = install_if
+    end
+
+    def normalize_group_options(opts, groups)
+      normalize_hash(opts)
+
+      groups = groups.map {|group| ":#{group}" }.join(", ")
+      validate_keys("group #{groups}", opts, %w[optional])
+
+      opts["optional"] ||= false
+    end
+
+    def validate_keys(command, opts, valid_keys)
+      if opts["branch"] && !(opts["git"] || opts["github"] || (opts.keys & @git_sources.keys.map(&:to_s)).any?)
+        raise GemfileError, %(The `branch` option for `#{command}` is not allowed. Only gems with a git source can specify a branch)
+      end
+
+      invalid_keys = opts.keys - valid_keys
+      return true unless invalid_keys.any?
+
+      message = String.new
+      message << "You passed #{invalid_keys.map {|k| ":" + k }.join(", ")} "
+      message << if invalid_keys.size > 1
+        "as options for #{command}, but they are invalid."
+      else
+        "as an option for #{command}, but it is invalid."
+      end
+
+      message << " Valid options are: #{valid_keys.join(", ")}."
+      message << " You may be able to resolve this by upgrading Bundler to the newest version."
+      raise InvalidOption, message
+    end
+
+    def normalize_source(source)
+      case source
+      when :gemcutter, :rubygems, :rubyforge
+        removed_message =
+          "The source :#{source} is disallowed because HTTP requests are insecure.\n" \
+          "Please change your source to 'https://rubygems.org' if possible, or 'http://rubygems.org' if not."
+        Bundler::SharedHelpers.feature_removed! removed_message
+      when String
+        source
+      else
+        raise GemfileError, "Unknown source '#{source}'"
+      end
+    end
+
+    def check_path_source_safety
+      return if @sources.global_path_source.nil?
+
+      msg = "You can no longer specify a path source by itself. Instead, \n" \
+              "either use the :path option on a gem, or specify the gems that \n" \
+              "bundler should find in the path source by passing a block to \n" \
+              "the path method, like: \n\n" \
+              "    path 'dir/containing/rails' do\n" \
+              "      gem 'rails'\n" \
+              "    end\n\n"
+
+      SharedHelpers.feature_removed! msg.strip
+    end
+
+    def check_rubygems_source_safety
+      multiple_global_source_warning if @sources.aggregate_global_source?
+    end
+
+    def multiple_global_source_warning
+      msg = "This Gemfile contains multiple global sources. " \
+        "Each source after the first must include a block to indicate which gems " \
+        "should come from that source"
+      raise GemfileEvalError, msg
+    end
+
+    class DSLError < GemfileError
+      # @return [String] the description that should be presented to the user.
+      #
+      attr_reader :description
+
+      # @return [String] the path of the dsl file that raised the exception.
+      #
+      attr_reader :dsl_path
+
+      # @return [Exception] the backtrace of the exception raised by the
+      #         evaluation of the dsl file.
+      #
+      attr_reader :backtrace
+
+      # @param [Exception] backtrace @see backtrace
+      # @param [String]    dsl_path  @see dsl_path
+      #
+      def initialize(description, dsl_path, backtrace, contents = nil)
+        @status_code = $!.respond_to?(:status_code) && $!.status_code
+
+        @description = description
+        @dsl_path    = dsl_path
+        @backtrace   = backtrace
+        @contents    = contents
+      end
+
+      def status_code
+        @status_code || super
+      end
+
+      # @return [String] the contents of the DSL that cause the exception to
+      #         be raised.
+      #
+      def contents
+        @contents ||= dsl_path && File.exist?(dsl_path) && File.read(dsl_path)
+      end
+
+      # The message of the exception reports the content of podspec for the
+      # line that generated the original exception.
+      #
+      # @example Output
+      #
+      #   Invalid podspec at `RestKit.podspec` - undefined method
+      #   `exclude_header_search_paths=' for #<Pod::Specification for
+      #   `RestKit/Network (0.9.3)`>
+      #
+      #       from spec-repos/master/RestKit/0.9.3/RestKit.podspec:36
+      #       -------------------------------------------
+      #           # because it would break: #import <CoreData/CoreData.h>
+      #    >      ns.exclude_header_search_paths = 'Code/RestKit.h'
+      #         end
+      #       -------------------------------------------
+      #
+      # @return [String] the message of the exception.
+      #
+      def to_s
+        @to_s ||= begin
+          trace_line, description = parse_line_number_from_description
+
+          m = String.new("\n[!] ")
+          m << description
+          m << ". Bundler cannot continue.\n"
+
+          return m unless backtrace && dsl_path && contents
+
+          trace_line = backtrace.find {|l| l.include?(dsl_path) } || trace_line
+          return m unless trace_line
+          line_number = trace_line.split(":")[1].to_i - 1
+          return m unless line_number
+
+          lines      = contents.lines.to_a
+          indent     = " #  "
+          indicator  = indent.tr("#", ">")
+          first_line = line_number.zero?
+          last_line  = (line_number == (lines.count - 1))
+
+          m << "\n"
+          m << "#{indent}from #{trace_line.gsub(/:in.*$/, "")}\n"
+          m << "#{indent}-------------------------------------------\n"
+          m << "#{indent}#{lines[line_number - 1]}" unless first_line
+          m << "#{indicator}#{lines[line_number]}"
+          m << "#{indent}#{lines[line_number + 1]}" unless last_line
+          m << "\n" unless m.end_with?("\n")
+          m << "#{indent}-------------------------------------------\n"
+        end
+      end
+
+      private
+
+      def parse_line_number_from_description
+        description = self.description
+        if dsl_path && description =~ /((#{Regexp.quote File.expand_path(dsl_path)}|#{Regexp.quote dsl_path}):\d+)/
+          trace_line = Regexp.last_match[1]
+          description = description.sub(/\n.*\n(\.\.\.)? *\^~+$/, "").sub(/#{Regexp.quote trace_line}:\s*/, "").sub("\n", " - ")
+        end
+        [trace_line, description]
+      end
+    end
+
+    def gemfile_root
+      @gemfile ||= Bundler.default_gemfile
+      @gemfile.dirname
+    end
+  end
+end
diff --git a/lib/bundler/endpoint_specification.rb b/lib/bundler/endpoint_specification.rb
new file mode 100644
index 0000000000..7c7ce107e2
--- /dev/null
+++ b/lib/bundler/endpoint_specification.rb
@@ -0,0 +1,184 @@
+# frozen_string_literal: true
+
+module Bundler
+  # used for Creating Specifications from the Gemcutter Endpoint
+  class EndpointSpecification < Gem::Specification
+    include MatchRemoteMetadata
+
+    attr_reader :name, :version, :platform, :checksum, :created_at
+    attr_writer :dependencies
+    attr_accessor :remote, :locked_platform
+
+    def initialize(name, version, platform, spec_fetcher, dependencies, metadata = nil)
+      super()
+      @name         = name
+      @version      = Gem::Version.create version
+      @platform     = Gem::Platform.new(platform)
+      @spec_fetcher = spec_fetcher
+      @dependencies = nil
+      @unbuilt_dependencies = dependencies
+
+      @loaded_from          = nil
+      @remote_specification = nil
+      @locked_platform = nil
+
+      parse_metadata(metadata)
+    end
+
+    def insecurely_materialized?
+      @locked_platform.to_s != @platform.to_s
+    end
+
+    def fetch_platform
+      @platform
+    end
+
+    def dependencies
+      @dependencies ||= @unbuilt_dependencies.map! {|dep, reqs| build_dependency(dep, reqs) }
+    end
+    alias_method :runtime_dependencies, :dependencies
+
+    # needed for standalone, load required_paths from local gemspec
+    # after the gem is installed
+    def require_paths
+      if @remote_specification
+        @remote_specification.require_paths
+      elsif _local_specification
+        _local_specification.require_paths
+      else
+        super
+      end
+    end
+
+    # needed for inline
+    def load_paths
+      # remote specs aren't installed, and can't have load_paths
+      if _local_specification
+        _local_specification.load_paths
+      else
+        super
+      end
+    end
+
+    # needed for binstubs
+    def executables
+      if @remote_specification
+        @remote_specification.executables
+      elsif _local_specification
+        _local_specification.executables
+      else
+        super
+      end
+    end
+
+    # needed for bundle clean
+    def bindir
+      if @remote_specification
+        @remote_specification.bindir
+      elsif _local_specification
+        _local_specification.bindir
+      else
+        super
+      end
+    end
+
+    # needed for post_install_messages during install
+    def post_install_message
+      if @remote_specification
+        @remote_specification.post_install_message
+      elsif _local_specification
+        _local_specification.post_install_message
+      else
+        super
+      end
+    end
+
+    # needed for "with native extensions" during install
+    def extensions
+      if @remote_specification
+        @remote_specification.extensions
+      elsif _local_specification
+        _local_specification.extensions
+      else
+        super
+      end
+    end
+
+    # needed for `bundle fund`
+    def metadata
+      if @remote_specification
+        @remote_specification.metadata
+      elsif _local_specification
+        _local_specification.metadata
+      else
+        super
+      end
+    end
+
+    def _local_specification
+      return unless @loaded_from && File.exist?(local_specification_path)
+      eval(File.read(local_specification_path), nil, local_specification_path).tap do |spec|
+        spec.loaded_from = @loaded_from
+      end
+    end
+
+    def __swap__(spec)
+      SharedHelpers.ensure_same_dependencies(self, dependencies, spec.dependencies)
+      @remote_specification = spec
+    end
+
+    def inspect
+      "#<#{self.class} @name=\"#{name}\" (#{full_name.delete_prefix("#{name}-")})>"
+    end
+
+    private
+
+    def _remote_specification
+      @_remote_specification ||= @spec_fetcher.fetch_spec([@name, @version, @platform])
+    end
+
+    def local_specification_path
+      "#{base_dir}/specifications/#{full_name}.gemspec"
+    end
+
+    def parse_metadata(data)
+      unless data
+        @required_ruby_version = nil
+        @required_rubygems_version = nil
+        @created_at = nil
+        return
+      end
+
+      data.each do |k, v|
+        next unless v
+        case k.to_s
+        when "checksum"
+          begin
+            @checksum = Checksum.from_api(v.last, @spec_fetcher.uri)
+          rescue ArgumentError => e
+            raise ArgumentError, "Invalid checksum for #{full_name}: #{e.message}"
+          end
+        when "rubygems"
+          @required_rubygems_version = Gem::Requirement.new(v)
+        when "ruby"
+          @required_ruby_version = Gem::Requirement.new(v)
+        when "created_at"
+          value = v.is_a?(Array) ? v.last : v
+          if value.is_a?(String)
+            @created_at = begin
+              Time.new(value)
+            rescue ArgumentError
+              nil
+            end
+          end
+        end
+      end
+    rescue StandardError => e
+      raise GemspecError, "There was an error parsing the metadata for the gem #{name} (#{version}): #{e.class}\n#{e}\nThe metadata was #{data.inspect}"
+    end
+
+    def build_dependency(name, requirements)
+      Dependency.new(name, requirements)
+    end
+  end
+end
diff --git a/lib/bundler/env.rb b/lib/bundler/env.rb
new file mode 100644
index 0000000000..2b29705060
--- /dev/null
+++ b/lib/bundler/env.rb
@@ -0,0 +1,129 @@
+# frozen_string_literal: true
+
+require_relative "rubygems_integration"
+require_relative "source/git/git_proxy"
+
+module Bundler
+  class Env
+    def self.write(io)
+      io.write report
+    end
+
+    def self.report(options = {})
+      print_gemfile = options.delete(:print_gemfile) { true }
+      print_gemspecs = options.delete(:print_gemspecs) { true }
+
+      out = String.new
+      append_formatted_table("Environment", environment, out)
+      append_formatted_table("Bundler Build Metadata", BuildMetadata.to_h, out)
+
+      unless Bundler.settings.all.empty?
+        out << "\n## Bundler settings\n\n```\n"
+        Bundler.settings.all.each do |setting|
+          out << setting << "\n"
+          Bundler.settings.pretty_values_for(setting).each do |line|
+            out << "  " << line << "\n"
+          end
+        end
+        out << "```\n"
+      end
+
+      return out unless SharedHelpers.in_bundle?
+
+      if print_gemfile
+        gemfiles = [Bundler.default_gemfile]
+        begin
+          gemfiles = Bundler.definition.gemfiles
+        rescue GemfileNotFound
+          nil
+        end
+
+        out << "\n## Gemfile\n"
+        gemfiles.each do |gemfile|
+          out << "\n### #{SharedHelpers.relative_path_to(gemfile)}\n\n"
+          out << "```ruby\n" << read_file(gemfile).chomp << "\n```\n"
+        end
+
+        out << "\n### #{SharedHelpers.relative_path_to(Bundler.default_lockfile)}\n\n"
+        out << "```\n" << read_file(Bundler.default_lockfile).chomp << "\n```\n"
+      end
+
+      if print_gemspecs
+        dsl = Dsl.new.tap {|d| d.eval_gemfile(Bundler.default_gemfile) }
+        out << "\n## Gemspecs\n" unless dsl.gemspecs.empty?
+        dsl.gemspecs.each do |gs|
+          out << "\n### #{File.basename(gs.loaded_from)}"
+          out << "\n\n```ruby\n" << read_file(gs.loaded_from).chomp << "\n```\n"
+        end
+      end
+
+      out
+    end
+
+    def self.read_file(filename)
+      Bundler.read_file(filename.to_s).strip
+    rescue Errno::ENOENT
+      "<No #{filename} found>"
+    rescue RuntimeError => e
+      "#{e.class}: #{e.message}"
+    end
+
+    def self.ruby_version
+      "#{RUBY_VERSION}p#{RUBY_PATCHLEVEL} (#{RUBY_RELEASE_DATE} revision #{RUBY_REVISION}) [#{Gem::Platform.local}]"
+    end
+
+    def self.git_version
+      Bundler::Source::Git::GitProxy.new(nil, nil).full_version
+    rescue Bundler::Source::Git::GitNotInstalledError
+      "not installed"
+    end
+
+    def self.environment
+      out = []
+
+      out << ["Bundler", Bundler::VERSION]
+      out << ["  Platforms", Gem.platforms.join(", ")]
+      out << ["Ruby", ruby_version]
+      out << ["  Full Path", Gem.ruby]
+      out << ["  Config Dir", Pathname.new(Gem::ConfigFile::SYSTEM_WIDE_CONFIG_FILE).dirname]
+      out << ["RubyGems", Gem::VERSION]
+      out << ["  Gem Home", Gem.dir]
+      out << ["  Gem Path", Gem.path.join(File::PATH_SEPARATOR)]
+      out << ["  User Home", Gem.user_home]
+      out << ["  User Path", Gem.user_dir]
+      out << ["  Bin Dir", Gem.bindir]
+      if defined?(OpenSSL::SSL)
+        out << ["OpenSSL"]
+        out << ["  Compiled", OpenSSL::OPENSSL_VERSION] if defined?(OpenSSL::OPENSSL_VERSION)
+        out << ["  Loaded", OpenSSL::OPENSSL_LIBRARY_VERSION] if defined?(OpenSSL::OPENSSL_LIBRARY_VERSION)
+        out << ["  Cert File", OpenSSL::X509::DEFAULT_CERT_FILE] if defined?(OpenSSL::X509::DEFAULT_CERT_FILE)
+        out << ["  Cert Dir", OpenSSL::X509::DEFAULT_CERT_DIR] if defined?(OpenSSL::X509::DEFAULT_CERT_DIR)
+      end
+      out << ["Git", git_version]
+
+      if (exe = caller_locations.last.absolute_path)&.match? %r{(exe|bin)/bundler?\z}
+        shebang = File.read(exe).lines.first
+        shebang.sub!(/^#!\s*/, "")
+        unless shebang.start_with?(Gem.ruby, "/usr/bin/env ruby")
+          out << ["Gem.ruby", Gem.ruby]
+          out << ["bundle #!", shebang]
+        end
+      end
+
+      out
+    end
+
+    def self.append_formatted_table(title, pairs, out)
+      return if pairs.empty?
+      out << "\n" unless out.empty?
+      out << "## #{title}\n\n```\n"
+      ljust = pairs.map {|k, _v| k.to_s.length }.max
+      pairs.each do |k, v|
+        out << "#{k.to_s.ljust(ljust)}  #{v}\n"
+      end
+      out << "```\n"
+    end
+
+    private_class_method :read_file, :ruby_version, :git_version, :append_formatted_table
+  end
+end
diff --git a/lib/bundler/environment_preserver.rb b/lib/bundler/environment_preserver.rb
new file mode 100644
index 0000000000..bf9478a299
--- /dev/null
+++ b/lib/bundler/environment_preserver.rb
@@ -0,0 +1,69 @@
+# frozen_string_literal: true
+
+module Bundler
+  class EnvironmentPreserver
+    INTENTIONALLY_NIL = "BUNDLER_ENVIRONMENT_PRESERVER_INTENTIONALLY_NIL"
+    BUNDLER_KEYS = %w[
+      BUNDLE_BIN_PATH
+      BUNDLE_GEMFILE
+      BUNDLE_LOCKFILE
+      BUNDLER_VERSION
+      BUNDLER_SETUP
+      GEM_HOME
+      GEM_PATH
+      MANPATH
+      PATH
+      RB_USER_INSTALL
+      RUBYLIB
+      RUBYOPT
+    ].map(&:freeze).freeze
+    BUNDLER_PREFIX = "BUNDLER_ORIG_"
+
+    def self.from_env
+      new(ENV.to_hash, BUNDLER_KEYS)
+    end
+
+    # @param env [Hash]
+    # @param keys [Array<String>]
+    def initialize(env, keys)
+      @original = env
+      @keys = keys
+      @prefix = BUNDLER_PREFIX
+    end
+
+    # Replaces `ENV` with the bundler environment variables backed up
+    def replace_with_backup
+      ENV.replace(backup)
+    end
+
+    # @return [Hash]
+    def backup
+      env = @original.clone
+      @keys.each do |key|
+        value = env[key]
+        if !value.nil?
+          env[@prefix + key] ||= value
+        else
+          env[@prefix + key] ||= INTENTIONALLY_NIL
+        end
+      end
+      env
+    end
+
+    # @return [Hash]
+    def restore
+      env = @original.clone
+      @keys.each do |key|
+        value_original = env[@prefix + key]
+        next if value_original.nil?
+        if value_original == INTENTIONALLY_NIL
+          env.delete(key)
+        else
+          env[key] = value_original
+        end
+        env.delete(@prefix + key)
+      end
+      env
+    end
+  end
+end
diff --git a/lib/bundler/errors.rb b/lib/bundler/errors.rb
new file mode 100644
index 0000000000..dff5d93128
--- /dev/null
+++ b/lib/bundler/errors.rb
@@ -0,0 +1,306 @@
+# frozen_string_literal: true
+
+module Bundler
+  class BundlerError < StandardError
+    def self.status_code(code)
+      define_method(:status_code) { code }
+      if match = BundlerError.all_errors.find {|_k, v| v == code }
+        error, _ = match
+        raise ArgumentError,
+          "Trying to register #{self} for status code #{code} but #{error} is already registered"
+      end
+      BundlerError.all_errors[self] = code
+    end
+
+    def self.all_errors
+      @all_errors ||= {}
+    end
+  end
+
+  class GemfileError < BundlerError; status_code(4); end
+  class InstallError < BundlerError; status_code(5); end
+
+  # Internal error, should be rescued
+  class SolveFailure < BundlerError; status_code(6); end
+
+  class GemNotFound < BundlerError; status_code(7); end
+  class InstallHookError < BundlerError; status_code(8); end
+  class RemovedError < BundlerError; status_code(9); end
+  class GemfileNotFound < BundlerError; status_code(10); end
+  class GitError < BundlerError; status_code(11); end
+  class DeprecatedError < BundlerError; status_code(12); end
+  class PathError < BundlerError; status_code(13); end
+  class GemspecError < BundlerError; status_code(14); end
+  class InvalidOption < BundlerError; status_code(15); end
+  class ProductionError < BundlerError; status_code(16); end
+
+  class HTTPError < BundlerError
+    status_code(17)
+    def filter_uri(uri)
+      URICredentialsFilter.credential_filtered_uri(uri)
+    end
+  end
+
+  class RubyVersionMismatch < BundlerError; status_code(18); end
+  class SecurityError < BundlerError; status_code(19); end
+  class LockfileError < BundlerError; status_code(20); end
+  class CyclicDependencyError < BundlerError; status_code(21); end
+  class GemfileLockNotFound < BundlerError; status_code(22); end
+  class PluginError < BundlerError; status_code(29); end
+  class ThreadCreationError < BundlerError; status_code(33); end
+  class APIResponseMismatchError < BundlerError; status_code(34); end
+  class APIResponseInvalidDependenciesError < BundlerError; status_code(35); end
+  class GemfileEvalError < GemfileError; end
+  class MarshalError < StandardError; end
+
+  class ChecksumMismatchError < SecurityError
+    def initialize(lock_name, existing, checksum)
+      @lock_name = lock_name
+      @existing = existing
+      @checksum = checksum
+    end
+
+    def message
+      <<~MESSAGE
+        Bundler found mismatched checksums. This is a potential security risk.
+          #{@lock_name} #{@existing.to_lock}
+            from #{@existing.sources.join("\n    and ")}
+          #{@lock_name} #{@checksum.to_lock}
+            from #{@checksum.sources.join("\n    and ")}
+
+        #{mismatch_resolution_instructions}
+        To ignore checksum security warnings, disable checksum validation with
+          `bundle config set --local disable_checksum_validation true`
+      MESSAGE
+    end
+
+    def mismatch_resolution_instructions
+      removable, remote = [@existing, @checksum].partition(&:removable?)
+      case removable.size
+      when 1
+        msg = +"If you trust #{remote.first.sources.first}, to resolve this issue you can:\n"
+        msg << removable.first.removal_instructions
+      when 2
+        msg = +"To resolve this issue you can either:\n"
+        msg << @checksum.removal_instructions
+        msg << "or if you are sure that the new checksum from #{@checksum.sources.first} is correct:\n"
+        msg << @existing.removal_instructions
+      end
+    end
+
+    status_code(37)
+  end
+
+  class PermissionError < BundlerError
+    def initialize(path, permission_type = :write)
+      @path = path
+      @permission_type = permission_type
+    end
+
+    def action
+      case @permission_type
+      when :read then "read from"
+      when :write then "write to"
+      when :executable, :exec then "execute"
+      else @permission_type.to_s
+      end
+    end
+
+    def permission_type
+      case @permission_type
+      when :create
+        "executable permissions for all parent directories and write permissions for `#{parent_folder}`"
+      else
+        "#{@permission_type} permissions for that path"
+      end
+    end
+
+    def parent_folder
+      File.dirname(@path)
+    end
+
+    def message
+      "There was an error while trying to #{action} `#{@path}`. " \
+      "It is likely that you need to grant #{permission_type}."
+    end
+
+    status_code(23)
+  end
+
+  class GemRequireError < BundlerError
+    attr_reader :orig_exception
+
+    def initialize(orig_exception, msg)
+      full_message = msg + "\nGem Load Error is:
+                      #{orig_exception.full_message(highlight: false)}\n"\
+                      "Backtrace for gem load error is:\n"\
+                      "#{orig_exception.backtrace.join("\n")}\n"\
+                      "Bundler Error Backtrace:\n"
+      super(full_message)
+      @orig_exception = orig_exception
+    end
+
+    status_code(24)
+  end
+
+  class YamlSyntaxError < BundlerError
+    attr_reader :orig_exception
+
+    def initialize(orig_exception, msg)
+      super(msg)
+      @orig_exception = orig_exception
+    end
+
+    status_code(25)
+  end
+
+  class TemporaryResourceError < PermissionError
+    def message
+      "There was an error while trying to #{action} `#{@path}`. " \
+      "Some resource was temporarily unavailable. It's suggested that you try" \
+      "the operation again."
+    end
+
+    status_code(26)
+  end
+
+  class VirtualProtocolError < BundlerError
+    def message
+      "There was an error relating to virtualization and file access. " \
+      "It is likely that you need to grant access to or mount some file system correctly."
+    end
+
+    status_code(27)
+  end
+
+  class OperationNotSupportedError < PermissionError
+    def message
+      "Attempting to #{action} `#{@path}` is unsupported by your OS."
+    end
+
+    status_code(28)
+  end
+
+  class NoSpaceOnDeviceError < PermissionError
+    def message
+      "There was an error while trying to #{action} `#{@path}`. " \
+      "There was insufficient space remaining on the device."
+    end
+
+    status_code(31)
+  end
+
+  class ReadOnlyFileSystemError < PermissionError
+    def message
+      "There was an error while trying to #{action} `#{@path}`. " \
+      "File system is read-only."
+    end
+
+    status_code(42)
+  end
+
+  class OperationNotPermittedError < PermissionError
+    def message
+      "There was an error while trying to #{action} `#{@path}`. " \
+      "Underlying OS system call raised an EPERM error."
+    end
+
+    status_code(43)
+  end
+
+  class GenericSystemCallError < BundlerError
+    attr_reader :underlying_error
+
+    def initialize(underlying_error, message)
+      @underlying_error = underlying_error
+      super("#{message}\nThe underlying system error is #{@underlying_error.class}: #{@underlying_error}")
+    end
+
+    status_code(32)
+  end
+
+  class DirectoryRemovalError < BundlerError
+    def initialize(orig_exception, msg)
+      full_message = "#{msg}.\n" \
+                     "The underlying error was #{orig_exception.class}:
+                     #{orig_exception.full_message(highlight: false)},
+                     with backtrace:\n" \
+                     "  #{orig_exception.backtrace.join("\n  ")}\n\n" \
+                     "Bundler Error Backtrace:"
+      super(full_message)
+    end
+
+    status_code(36)
+  end
+
+  class InsecureInstallPathError < BundlerError
+    def initialize(name, path)
+      @name = name
+      @path = path
+    end
+
+    def message
+      "Bundler cannot reinstall #{@name} because there's a previous installation of it at #{@path} that is unsafe to remove.\n" \
+      "The parent of #{@path} is world-writable and does not have the sticky bit set, making it insecure to remove due to potential vulnerabilities.\n" \
+      "Please change the permissions of #{File.dirname(@path)} or choose a different install path."
+    end
+
+    status_code(38)
+  end
+
+  class CorruptBundlerInstallError < BundlerError
+    def initialize(loaded_spec)
+      @loaded_spec = loaded_spec
+    end
+
+    def message
+      "The running version of Bundler (#{Bundler::VERSION}) does not match the version of the specification installed for it (#{@loaded_spec.version}). " \
+      "This can be caused by reinstalling Ruby without removing previous installation, leaving around an upgraded default version of Bundler. " \
+      "Reinstalling Ruby from scratch should fix the problem."
+    end
+
+    status_code(39)
+  end
+
+  class InvalidArgumentError < BundlerError; status_code(40); end
+
+  class IncorrectLockfileDependencies < BundlerError
+    attr_reader :spec, :actual_dependencies, :lockfile_dependencies
+
+    def initialize(spec, actual_dependencies = nil, lockfile_dependencies = nil)
+      @spec = spec
+      @actual_dependencies = actual_dependencies
+      @lockfile_dependencies = lockfile_dependencies
+    end
+
+    def message
+      lines = ["Bundler found incorrect dependencies in the lockfile for #{spec.full_name}", ""]
+
+      if @actual_dependencies && @lockfile_dependencies
+        actual_by_name = @actual_dependencies.each_with_object({}) {|d, h| h[d.name] = d }
+        lockfile_by_name = @lockfile_dependencies.each_with_object({}) {|d, h| h[d.name] = d }
+
+        (actual_by_name.keys | lockfile_by_name.keys).sort.each do |name|
+          actual = actual_by_name[name]
+          lockfile = lockfile_by_name[name]
+          next if actual && lockfile && actual.requirement == lockfile.requirement
+
+          if actual && lockfile
+            lines << "  #{name}: gemspec specifies #{actual.requirement}, lockfile has #{lockfile.requirement}"
+          elsif actual
+            lines << "  #{name}: gemspec specifies #{actual.requirement}, not in lockfile"
+          else
+            lines << "  #{name}: not in gemspec, lockfile has #{lockfile.requirement}"
+          end
+        end
+
+        lines << ""
+      end
+
+      lines << "Please run `bundle install` to regenerate the lockfile."
+      lines.join("\n")
+    end
+
+    status_code(41)
+  end
+end
diff --git a/lib/bundler/feature_flag.rb b/lib/bundler/feature_flag.rb
new file mode 100644
index 0000000000..dea8abedba
--- /dev/null
+++ b/lib/bundler/feature_flag.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+module Bundler
+  class FeatureFlag
+    (1..10).each {|v| define_method("bundler_#{v}_mode?") { @major_version >= v } }
+
+    def removed_major?(target_major_version)
+      @major_version > target_major_version
+    end
+
+    def deprecated_major?(target_major_version)
+      @major_version >= target_major_version
+    end
+
+    def initialize(bundler_version)
+      @bundler_version = Gem::Version.create(bundler_version)
+      @major_version = @bundler_version.segments.first
+    end
+  end
+end
diff --git a/lib/bundler/fetcher.rb b/lib/bundler/fetcher.rb
new file mode 100644
index 0000000000..0b6ced6f39
--- /dev/null
+++ b/lib/bundler/fetcher.rb
@@ -0,0 +1,361 @@
+# frozen_string_literal: true
+
+require_relative "vendored_persistent"
+require_relative "vendored_timeout"
+require_relative "vendored_securerandom"
+require "zlib"
+
+module Bundler
+  # Handles all the fetching with the rubygems server
+  class Fetcher
+    autoload :Base, File.expand_path("fetcher/base", __dir__)
+    autoload :CompactIndex, File.expand_path("fetcher/compact_index", __dir__)
+    autoload :Downloader, File.expand_path("fetcher/downloader", __dir__)
+    autoload :Dependency, File.expand_path("fetcher/dependency", __dir__)
+    autoload :Index, File.expand_path("fetcher/index", __dir__)
+
+    # This error is raised when it looks like the network is down
+    class NetworkDownError < HTTPError; end
+    # This error is raised if we should rate limit our requests to the API
+    class TooManyRequestsError < HTTPError; end
+    # This error is raised if the API returns a 413 (only printed in verbose)
+    class FallbackError < HTTPError; end
+
+    # This is the error raised if OpenSSL fails the cert verification
+    class CertificateFailureError < HTTPError
+      def initialize(remote_uri)
+        remote_uri = filter_uri(remote_uri)
+        super "Could not verify the SSL certificate for #{remote_uri}.\nThere" \
+          " is a chance you are experiencing a man-in-the-middle attack, but" \
+          " most likely your system doesn't have the CA certificates needed" \
+          " for verification. For information about OpenSSL certificates, see" \
+          " https://railsapps.github.io/openssl-certificate-verify-failed.html."
+      end
+    end
+
+    # This is the error raised when a source is HTTPS and OpenSSL didn't load
+    class SSLError < HTTPError
+      def initialize(msg = nil)
+        super "Could not load OpenSSL.\n" \
+          "You must recompile Ruby with OpenSSL support.\n" \
+          "original error: #{msg}\n"
+      end
+    end
+
+    # This error is raised if HTTP authentication is required, but not provided.
+    class AuthenticationRequiredError < HTTPError
+      def initialize(remote_uri)
+        remote_uri = filter_uri(remote_uri)
+        super "Authentication is required for #{remote_uri}.\n" \
+          "Please supply credentials for this source. You can do this by running:\n" \
+          "`bundle config set --global #{remote_uri} username:password`\n" \
+          "or by storing the credentials in the `#{Settings.key_for(remote_uri)}` environment variable"
+      end
+    end
+
+    # This error is raised if HTTP authentication is provided, but incorrect.
+    class BadAuthenticationError < HTTPError
+      def initialize(remote_uri)
+        remote_uri = filter_uri(remote_uri)
+        super "Bad username or password for #{remote_uri}.\n" \
+          "Please double-check your credentials and correct them."
+      end
+    end
+
+    # This error is raised if HTTP authentication is correct, but lacks
+    # necessary permissions.
+    class AuthenticationForbiddenError < HTTPError
+      def initialize(remote_uri)
+        remote_uri = filter_uri(remote_uri)
+        super "Access token could not be authenticated for #{remote_uri}.\n" \
+          "Make sure it's valid and has the necessary scopes configured."
+      end
+    end
+
+    HTTP_ERRORS = (Downloader::HTTP_RETRYABLE_ERRORS + Downloader::HTTP_NON_RETRYABLE_ERRORS).freeze
+    deprecate_constant :HTTP_ERRORS
+
+    NET_ERRORS = [
+      :HTTPBadGateway,
+      :HTTPBadRequest,
+      :HTTPFailedDependency,
+      :HTTPForbidden,
+      :HTTPInsufficientStorage,
+      :HTTPMethodNotAllowed,
+      :HTTPMovedPermanently,
+      :HTTPNoContent,
+      :HTTPNotFound,
+      :HTTPNotImplemented,
+      :HTTPPreconditionFailed,
+      :HTTPRequestEntityTooLarge,
+      :HTTPRequestURITooLong,
+      :HTTPUnauthorized,
+      :HTTPUnprocessableEntity,
+      :HTTPUnsupportedMediaType,
+      :HTTPVersionNotSupported,
+    ].freeze
+    deprecate_constant :NET_ERRORS
+
+    # Exceptions classes that should bypass retry attempts. If your password didn't work the
+    # first time, it's not going to the third time.
+    FAIL_ERRORS = [
+      AuthenticationRequiredError,
+      BadAuthenticationError,
+      AuthenticationForbiddenError,
+      FallbackError,
+      SecurityError,
+      Gem::Requirement::BadRequirementError,
+      Gem::Net::HTTPBadGateway,
+      Gem::Net::HTTPBadRequest,
+      Gem::Net::HTTPFailedDependency,
+      Gem::Net::HTTPForbidden,
+      Gem::Net::HTTPInsufficientStorage,
+      Gem::Net::HTTPMethodNotAllowed,
+      Gem::Net::HTTPMovedPermanently,
+      Gem::Net::HTTPNoContent,
+      Gem::Net::HTTPNotFound,
+      Gem::Net::HTTPNotImplemented,
+      Gem::Net::HTTPPreconditionFailed,
+      Gem::Net::HTTPRequestEntityTooLarge,
+      Gem::Net::HTTPRequestURITooLong,
+      Gem::Net::HTTPUnauthorized,
+      Gem::Net::HTTPUnprocessableEntity,
+      Gem::Net::HTTPUnsupportedMediaType,
+      Gem::Net::HTTPVersionNotSupported,
+    ].freeze
+
+    class << self
+      attr_accessor :disable_endpoint, :api_timeout, :redirect_limit, :max_retries
+    end
+
+    self.redirect_limit = Bundler.settings[:redirect] # How many redirects to allow in one request
+    self.api_timeout    = Bundler.settings[:timeout] # How long to wait for each API call
+    self.max_retries    = Bundler.settings[:retry] # How many retries for the API call
+
+    def initialize(remote)
+      @cis = nil
+      @remote = remote
+
+      Socket.do_not_reverse_lookup = true
+      connection # create persistent connection
+    end
+
+    def uri
+      @remote.anonymized_uri
+    end
+
+    # fetch a gem specification
+    def fetch_spec(spec)
+      spec -= [nil, "ruby", ""]
+      spec_file_name = "#{spec.join "-"}.gemspec"
+
+      uri = Gem::URI.parse("#{remote_uri}#{Gem::MARSHAL_SPEC_DIR}#{spec_file_name}.rz")
+      spec = if uri.scheme == "file"
+        path = Gem::Util.correct_for_windows_path(uri.path)
+        Bundler.safe_load_marshal Bundler.rubygems.inflate(Gem.read_binary(path))
+      elsif cached_spec_path = gemspec_cached_path(spec_file_name)
+        Bundler.load_gemspec(cached_spec_path)
+      else
+        Bundler.safe_load_marshal Bundler.rubygems.inflate(downloader.fetch(uri).body)
+      end
+      raise MarshalError, "is #{spec.inspect}" unless spec.is_a?(Gem::Specification)
+      spec
+    rescue MarshalError
+      raise HTTPError, "Gemspec #{spec} contained invalid data.\n" \
+        "Your network or your gem server is probably having issues right now."
+    end
+
+    # return the specs in the bundler format as an index with retries
+    def specs_with_retry(gem_names, source)
+      Bundler::Retry.new("fetcher", FAIL_ERRORS).attempts do
+        specs(gem_names, source)
+      end
+    end
+
+    # return the specs in the bundler format as an index
+    def specs(gem_names, source)
+      index = Bundler::Index.new
+
+      fetch_specs(gem_names).each do |name, version, platform, dependencies, metadata|
+        spec = if dependencies
+          EndpointSpecification.new(name, version, platform, self, dependencies, metadata).tap do |es|
+            source.checksum_store.replace(es, es.checksum)
+          end
+        else
+          RemoteSpecification.new(name, version, platform, self)
+        end
+        spec.source = source
+        spec.remote = @remote
+        index << spec
+      end
+
+      index
+    rescue CertificateFailureError
+      Bundler.ui.info "" if gem_names && api_fetcher? # newline after dots
+      raise
+    end
+
+    def user_agent
+      @user_agent ||= begin
+        ruby = Bundler::RubyVersion.system
+
+        agent = String.new("bundler/#{Bundler::VERSION}")
+        agent << " rubygems/#{Gem::VERSION}"
+        agent << " ruby/#{ruby.versions_string(ruby.versions)}"
+        agent << " (#{ruby.host})"
+        agent << " command/#{ARGV.first}"
+
+        if ruby.engine != "ruby"
+          # engine_version raises on unknown engines
+          engine_version = begin
+                             ruby.engine_versions
+                           rescue RuntimeError
+                             "???"
+                           end
+          agent << " #{ruby.engine}/#{ruby.versions_string(engine_version)}"
+        end
+
+        agent << " options/#{Bundler.settings.all.join(",")}"
+
+        agent << " ci/#{cis.join(",")}" if cis.any?
+
+        # add a random ID so we can consolidate runs server-side
+        agent << " " << Gem::SecureRandom.hex(8)
+
+        # add any user agent strings set in the config
+        extra_ua = Bundler.settings[:user_agent]
+        agent << " " << extra_ua if extra_ua
+
+        agent
+      end
+    end
+
+    def http_proxy
+      return unless uri = connection.proxy_uri
+      uri.to_s
+    end
+
+    def inspect
+      "#<#{self.class}:0x#{object_id} uri=#{uri}>"
+    end
+
+    def api_fetcher?
+      fetchers.first.api_fetcher?
+    end
+
+    def gem_remote_fetcher
+      @gem_remote_fetcher ||= begin
+        require_relative "fetcher/gem_remote_fetcher"
+        fetcher = GemRemoteFetcher.new Gem.configuration[:http_proxy]
+        fetcher.headers["User-Agent"] = user_agent
+        fetcher.headers["X-Gemfile-Source"] = @remote.original_uri.to_s if @remote.original_uri
+        fetcher
+      end
+    end
+
+    private
+
+    def available_fetchers
+      if Bundler::Fetcher.disable_endpoint
+        [Index]
+      elsif remote_uri.scheme == "file"
+        Bundler.ui.debug("Using a local server, bundler won't use the CompactIndex API")
+        [Index]
+      else
+        [CompactIndex, Dependency, Index]
+      end
+    end
+
+    def fetchers
+      @fetchers ||= available_fetchers.map {|f| f.new(downloader, @remote, uri, gem_remote_fetcher) }.drop_while {|f| !f.available? }
+    end
+
+    def fetch_specs(gem_names)
+      fetchers.reject!(&:api_fetcher?) unless gem_names
+      fetchers.reject! do |f|
+        specs = f.specs(gem_names)
+        return specs if specs
+        true
+      end
+      []
+    end
+
+    def cis
+      @cis ||= Bundler::CIDetector.ci_strings
+    end
+
+    def connection
+      @connection ||= begin
+        needs_ssl = remote_uri.scheme == "https" ||
+                    Bundler.settings[:ssl_verify_mode] ||
+                    Bundler.settings[:ssl_client_cert]
+        if needs_ssl
+          begin
+            require "openssl"
+          rescue StandardError, LoadError => e
+            raise SSLError.new(e.message)
+          end
+        end
+
+        con = Gem::Net::HTTP::Persistent.new name: "bundler", proxy: :ENV
+        if gem_proxy = Gem.configuration[:http_proxy]
+          con.proxy = Gem::URI.parse(gem_proxy) if gem_proxy != :no_proxy
+        end
+
+        if remote_uri.scheme == "https"
+          con.verify_mode = (Bundler.settings[:ssl_verify_mode] ||
+            OpenSSL::SSL::VERIFY_PEER)
+          con.cert_store = bundler_cert_store
+        end
+
+        ssl_client_cert = Bundler.settings[:ssl_client_cert] ||
+                          (Gem.configuration.ssl_client_cert if
+                            Gem.configuration.respond_to?(:ssl_client_cert))
+        if ssl_client_cert
+          pem = File.read(ssl_client_cert)
+          con.cert = OpenSSL::X509::Certificate.new(pem)
+          con.key  = OpenSSL::PKey::RSA.new(pem)
+        end
+
+        con.read_timeout = Fetcher.api_timeout
+        con.open_timeout = Fetcher.api_timeout
+        con.override_headers["User-Agent"] = user_agent
+        con.override_headers["X-Gemfile-Source"] = @remote.original_uri.to_s if @remote.original_uri
+        con
+      end
+    end
+
+    # cached gem specification path, if one exists
+    def gemspec_cached_path(spec_file_name)
+      paths = Bundler.rubygems.spec_cache_dirs.map {|dir| File.join(dir, spec_file_name) }
+      paths.find {|path| File.file? path }
+    end
+
+    def bundler_cert_store
+      store = OpenSSL::X509::Store.new
+      ssl_ca_cert = Bundler.settings[:ssl_ca_cert] ||
+                    (Gem.configuration.ssl_ca_cert if
+                      Gem.configuration.respond_to?(:ssl_ca_cert))
+      if ssl_ca_cert
+        if File.directory? ssl_ca_cert
+          store.add_path ssl_ca_cert
+        else
+          store.add_file ssl_ca_cert
+        end
+      else
+        store.set_default_paths
+        require "rubygems/request"
+        Gem::Request.get_cert_files.each {|c| store.add_file c }
+      end
+      store
+    end
+
+    def remote_uri
+      @remote.uri
+    end
+
+    def downloader
+      @downloader ||= Downloader.new(connection, self.class.redirect_limit)
+    end
+  end
+end
diff --git a/lib/bundler/fetcher/base.rb b/lib/bundler/fetcher/base.rb
new file mode 100644
index 0000000000..cfec2f8e94
--- /dev/null
+++ b/lib/bundler/fetcher/base.rb
@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Fetcher
+    class Base
+      attr_reader :downloader
+      attr_reader :display_uri
+      attr_reader :remote
+      attr_reader :gem_remote_fetcher
+
+      def initialize(downloader, remote, display_uri, gem_remote_fetcher)
+        raise "Abstract class" if self.class == Base
+        @downloader = downloader
+        @remote = remote
+        @display_uri = display_uri
+        @gem_remote_fetcher = gem_remote_fetcher
+      end
+
+      def remote_uri
+        @remote.uri
+      end
+
+      def fetch_uri
+        @fetch_uri ||= if remote_uri.host == "rubygems.org"
+          uri = remote_uri.dup
+          uri.host = "index.rubygems.org"
+          uri
+        else
+          remote_uri
+        end
+      end
+
+      def available?
+        true
+      end
+
+      def api_fetcher?
+        false
+      end
+
+      private
+
+      def log_specs(&block)
+        if Bundler.ui.debug?
+          Bundler.ui.debug yield
+        else
+          Bundler.ui.info ".", false
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/fetcher/compact_index.rb b/lib/bundler/fetcher/compact_index.rb
new file mode 100644
index 0000000000..52168111fe
--- /dev/null
+++ b/lib/bundler/fetcher/compact_index.rb
@@ -0,0 +1,120 @@
+# frozen_string_literal: true
+
+require_relative "base"
+require_relative "../worker"
+
+module Bundler
+  class Fetcher
+    class CompactIndex < Base
+      def self.compact_index_request(method_name)
+        method = instance_method(method_name)
+        undef_method(method_name)
+        define_method(method_name) do |*args, &blk|
+          method.bind_call(self, *args, &blk)
+        rescue NetworkDownError, CompactIndexClient::Updater::MismatchedChecksumError => e
+          raise HTTPError, e.message
+        rescue AuthenticationRequiredError, BadAuthenticationError
+          # Fail since we got a 401 from the server.
+          raise
+        rescue HTTPError => e
+          Bundler.ui.trace(e)
+          nil
+        end
+      end
+
+      def specs(gem_names)
+        specs_for_names(gem_names)
+      end
+      compact_index_request :specs
+
+      def specs_for_names(gem_names)
+        gem_info = []
+        complete_gems = []
+        remaining_gems = gem_names.dup
+
+        until remaining_gems.empty?
+          log_specs { "Looking up gems #{remaining_gems.inspect}" }
+          deps = fetch_gem_infos(remaining_gems).flatten(1)
+          next_gems = deps.flat_map {|d| d[CompactIndexClient::INFO_DEPS].flat_map(&:first) }.uniq
+          deps.each {|dep| gem_info << dep }
+          complete_gems.concat(deps.map(&:first)).uniq!
+          remaining_gems = next_gems - complete_gems
+        end
+        @bundle_worker&.stop
+        @bundle_worker = nil # reset it.  Not sure if necessary
+
+        gem_info
+      end
+
+      def available?
+        unless SharedHelpers.md5_available?
+          Bundler.ui.debug("FIPS mode is enabled, bundler can't use the CompactIndex API")
+          return nil
+        end
+        # Read info file checksums out of /versions, so we can know if gems are up to date
+        compact_index_client.available?
+      rescue CompactIndexClient::Updater::MismatchedChecksumError => e
+        Bundler.ui.debug(e.message)
+        nil
+      end
+      compact_index_request :available?
+
+      def api_fetcher?
+        true
+      end
+
+      private
+
+      def compact_index_client
+        @compact_index_client ||=
+          SharedHelpers.filesystem_access(cache_path) do
+            CompactIndexClient.new(cache_path, client_fetcher)
+          end
+      end
+
+      def fetch_gem_infos(names)
+        in_parallel(names) {|name| compact_index_client.info(name) }
+      rescue TooManyRequestsError # rubygems.org is rate limiting us, slow down.
+        @bundle_worker&.stop
+        @bundle_worker = nil # reset it.  Not sure if necessary
+        compact_index_client.reset!
+        names.map {|name| compact_index_client.info(name) }
+      end
+
+      def in_parallel(inputs, &blk)
+        func = lambda {|object, _index| blk.call(object) }
+        worker = bundle_worker(func)
+        inputs.each {|input| worker.enq(input) }
+        inputs.map { worker.deq }
+      end
+
+      def bundle_worker(func = nil)
+        @bundle_worker ||= begin
+          worker_name = "Compact Index (#{display_uri.host})"
+          Bundler::Worker.new(Bundler.settings.processor_count, worker_name, func)
+        end
+        @bundle_worker.tap do |worker|
+          worker.instance_variable_set(:@func, func) if func
+        end
+      end
+
+      def cache_path
+        Bundler.user_cache.join("compact_index", remote.cache_slug)
+      end
+
+      def client_fetcher
+        ClientFetcher.new(self, Bundler.ui)
+      end
+
+      ClientFetcher = Struct.new(:fetcher, :ui) do
+        def call(path, headers)
+          fetcher.downloader.fetch(fetcher.fetch_uri + path, headers)
+        rescue NetworkDownError => e
+          raise unless headers["If-None-Match"]
+          ui.warn "Using the cached data for the new index because of a network error: #{e}"
+          Gem::Net::HTTPNotModified.new(nil, nil, nil)
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/fetcher/dependency.rb b/lib/bundler/fetcher/dependency.rb
new file mode 100644
index 0000000000..4f2414e33d
--- /dev/null
+++ b/lib/bundler/fetcher/dependency.rb
@@ -0,0 +1,85 @@
+# frozen_string_literal: true
+
+require_relative "base"
+require "cgi/escape"
+require "cgi/util" unless defined?(CGI::EscapeExt)
+
+module Bundler
+  class Fetcher
+    class Dependency < Base
+      def available?
+        @available ||= fetch_uri.scheme != "file" && downloader.fetch(dependency_api_uri)
+      rescue NetworkDownError => e
+        raise HTTPError, e.message
+      rescue AuthenticationRequiredError
+        # Fail since we got a 401 from the server.
+        raise
+      rescue HTTPError
+        false
+      end
+
+      def api_fetcher?
+        true
+      end
+
+      def specs(gem_names, full_dependency_list = [], last_spec_list = [])
+        query_list = gem_names.uniq - full_dependency_list
+
+        log_specs { "Query List: #{query_list.inspect}" }
+
+        return last_spec_list if query_list.empty?
+
+        spec_list, deps_list = Bundler::Retry.new("dependency api", FAIL_ERRORS).attempts do
+          dependency_specs(query_list)
+        end
+
+        returned_gems = spec_list.map(&:first).uniq
+        specs(deps_list, full_dependency_list + returned_gems, spec_list + last_spec_list)
+      rescue MarshalError, HTTPError, GemspecError
+        Bundler.ui.info "" unless Bundler.ui.debug? # new line now that the dots are over
+        Bundler.ui.debug "could not fetch from the dependency API, trying the full index"
+        nil
+      end
+
+      def dependency_specs(gem_names)
+        Bundler.ui.debug "Query Gemcutter Dependency Endpoint API: #{gem_names.join(",")}"
+
+        gem_list = unmarshalled_dep_gems(gem_names)
+        get_formatted_specs_and_deps(gem_list)
+      end
+
+      def unmarshalled_dep_gems(gem_names)
+        gem_list = []
+        gem_names.each_slice(api_request_size) do |names|
+          marshalled_deps = downloader.fetch(dependency_api_uri(names)).body
+          gem_list.concat(Bundler.safe_load_marshal(marshalled_deps))
+        end
+        gem_list
+      end
+
+      def get_formatted_specs_and_deps(gem_list)
+        deps_list = []
+        spec_list = []
+
+        gem_list.each do |s|
+          deps_list.concat(s[:dependencies].map(&:first))
+          deps = s[:dependencies].map {|n, d| [n, d.split(", ")] }
+          spec_list.push([s[:name], s[:number], s[:platform], deps])
+        end
+        [spec_list, deps_list]
+      end
+
+      def dependency_api_uri(gem_names = [])
+        uri = fetch_uri + "api/v1/dependencies"
+        uri.query = "gems=#{CGI.escape(gem_names.sort.join(","))}" if gem_names.any?
+        uri
+      end
+
+      private
+
+      def api_request_size
+        Bundler.settings[:api_request_size]&.to_i || Source::Rubygems::API_REQUEST_SIZE
+      end
+    end
+  end
+end
diff --git a/lib/bundler/fetcher/downloader.rb b/lib/bundler/fetcher/downloader.rb
new file mode 100644
index 0000000000..179eed8340
--- /dev/null
+++ b/lib/bundler/fetcher/downloader.rb
@@ -0,0 +1,116 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Fetcher
+    class Downloader
+      HTTP_NON_RETRYABLE_ERRORS = [
+        SocketError,
+        Errno::EADDRNOTAVAIL,
+        Errno::ENETDOWN,
+        Errno::ENETUNREACH,
+        Gem::Net::HTTP::Persistent::Error,
+        Errno::EHOSTUNREACH,
+      ].freeze
+
+      HTTP_RETRYABLE_ERRORS = [
+        Gem::Timeout::Error,
+        EOFError,
+        Errno::EINVAL,
+        Errno::ECONNRESET,
+        Errno::ETIMEDOUT,
+        Errno::EAGAIN,
+        Gem::Net::HTTPBadResponse,
+        Gem::Net::HTTPHeaderSyntaxError,
+        Gem::Net::ProtocolError,
+        Zlib::BufError,
+      ].freeze
+
+      attr_reader :connection
+      attr_reader :redirect_limit
+
+      def initialize(connection, redirect_limit)
+        @connection = connection
+        @redirect_limit = redirect_limit
+      end
+
+      def fetch(uri, headers = {}, counter = 0)
+        raise HTTPError, "Too many redirects" if counter >= redirect_limit
+
+        filtered_uri = URICredentialsFilter.credential_filtered_uri(uri)
+
+        response = request(uri, headers)
+        Bundler.ui.debug("HTTP #{response.code} #{response.message} #{filtered_uri}")
+
+        case response
+        when Gem::Net::HTTPSuccess, Gem::Net::HTTPNotModified
+          response
+        when Gem::Net::HTTPRedirection
+          new_uri = Gem::URI.parse(response["location"])
+          if new_uri.host == uri.host
+            new_uri.user = uri.user
+            new_uri.password = uri.password
+          end
+          fetch(new_uri, headers, counter + 1)
+        when Gem::Net::HTTPRequestedRangeNotSatisfiable
+          new_headers = headers.dup
+          new_headers.delete("Range")
+          fetch(uri, new_headers)
+        when Gem::Net::HTTPRequestEntityTooLarge
+          raise FallbackError, response.body
+        when Gem::Net::HTTPTooManyRequests
+          raise TooManyRequestsError, response.body
+        when Gem::Net::HTTPUnauthorized
+          raise BadAuthenticationError, uri.host if uri.userinfo
+          raise AuthenticationRequiredError, uri.host
+        when Gem::Net::HTTPForbidden
+          raise AuthenticationForbiddenError, uri.host
+        when Gem::Net::HTTPNotFound
+          raise FallbackError, "Gem::Net::HTTPNotFound: #{filtered_uri}"
+        else
+          message = "Gem::#{response.class.name.gsub(/\AGem::/, "")}"
+          message += ": #{response.body}" unless response.body.empty?
+          raise HTTPError, message
+        end
+      end
+
+      def request(uri, headers)
+        validate_uri_scheme!(uri)
+
+        filtered_uri = URICredentialsFilter.credential_filtered_uri(uri)
+
+        Bundler.ui.debug "HTTP GET #{filtered_uri}"
+        req = Gem::Net::HTTP::Get.new uri.request_uri, headers
+        if uri.user
+          user = CGI.unescape(uri.user)
+          password = uri.password ? CGI.unescape(uri.password) : nil
+          req.basic_auth(user, password)
+        end
+        connection.request(uri, req)
+      rescue OpenSSL::SSL::SSLError
+        raise CertificateFailureError.new(uri)
+      rescue *HTTP_NON_RETRYABLE_ERRORS => e
+        Bundler.ui.trace e
+
+        host = uri.host
+        host_port = "#{host}:#{uri.port}"
+        host = host_port if filtered_uri.to_s.include?(host_port)
+        raise NetworkDownError, "Could not reach host #{host}. Check your network " \
+          "connection and try again."
+      rescue *HTTP_RETRYABLE_ERRORS => e
+        Bundler.ui.trace e
+
+        raise HTTPError, "Network error while fetching #{filtered_uri}" \
+            " (#{e})"
+      end
+
+      private
+
+      def validate_uri_scheme!(uri)
+        return if /\Ahttps?\z/.match?(uri.scheme)
+        raise InvalidOption,
+          "The request uri `#{uri}` has an invalid scheme (`#{uri.scheme}`). " \
+          "Did you mean `http` or `https`?"
+      end
+    end
+  end
+end
diff --git a/lib/bundler/fetcher/gem_remote_fetcher.rb b/lib/bundler/fetcher/gem_remote_fetcher.rb
new file mode 100644
index 0000000000..3159e05688
--- /dev/null
+++ b/lib/bundler/fetcher/gem_remote_fetcher.rb
@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+require "rubygems/remote_fetcher"
+
+module Bundler
+  class Fetcher
+    class GemRemoteFetcher < Gem::RemoteFetcher
+      def initialize(*)
+        super
+
+        @pool_size = Bundler.settings.installation_parallelization
+      end
+
+      def request(*args)
+        super do |req|
+          req.delete("User-Agent") if headers["User-Agent"]
+          yield req if block_given?
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/fetcher/index.rb b/lib/bundler/fetcher/index.rb
new file mode 100644
index 0000000000..6e37e1e5d1
--- /dev/null
+++ b/lib/bundler/fetcher/index.rb
@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+require_relative "base"
+
+module Bundler
+  class Fetcher
+    class Index < Base
+      def specs(_gem_names)
+        Bundler.rubygems.fetch_all_remote_specs(remote, gem_remote_fetcher)
+      rescue Gem::RemoteFetcher::FetchError => e
+        case e.message
+        when /certificate verify failed/
+          raise CertificateFailureError.new(display_uri)
+        when /401/
+          raise BadAuthenticationError, remote_uri if remote_uri.userinfo
+          raise AuthenticationRequiredError, remote_uri
+        when /403/
+          raise AuthenticationForbiddenError, remote_uri
+        else
+          raise HTTPError, "Could not fetch specs from #{display_uri} due to underlying error <#{e.message}>"
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/force_platform.rb b/lib/bundler/force_platform.rb
new file mode 100644
index 0000000000..7af33218cb
--- /dev/null
+++ b/lib/bundler/force_platform.rb
@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+module Bundler
+  module ForcePlatform
+    # The `:force_ruby_platform` value used by dependencies for resolution, and
+    # by locked specifications for materialization is `false` by default, except
+    # for TruffleRuby. TruffleRuby generally needs to force the RUBY platform
+    # variant unless the name is explicitly allowlisted.
+
+    def default_force_ruby_platform
+      return false unless RUBY_ENGINE == "truffleruby"
+
+      !Gem::Platform::REUSE_AS_BINARY_ON_TRUFFLERUBY.include?(name)
+    end
+  end
+end
diff --git a/lib/bundler/friendly_errors.rb b/lib/bundler/friendly_errors.rb
new file mode 100644
index 0000000000..5e8eaee6bb
--- /dev/null
+++ b/lib/bundler/friendly_errors.rb
@@ -0,0 +1,127 @@
+# frozen_string_literal: true
+
+require_relative "vendored_thor"
+
+module Bundler
+  module FriendlyErrors
+    module_function
+
+    def enable!
+      @disabled = false
+    end
+
+    def disabled?
+      @disabled
+    end
+
+    def disable!
+      @disabled = true
+    end
+
+    def log_error(error)
+      case error
+      when YamlSyntaxError
+        Bundler.ui.error error.message
+        Bundler.ui.trace error.orig_exception
+      when Dsl::DSLError, GemspecError
+        Bundler.ui.error error.message
+      when GemRequireError
+        Bundler.ui.error error.message
+        Bundler.ui.trace error.orig_exception
+      when BundlerError
+        if Bundler.ui.debug?
+          Bundler.ui.trace error
+        else
+          Bundler.ui.error error.message, wrap: true
+        end
+      when Thor::Error
+        Bundler.ui.error error.message
+      when Interrupt
+        Bundler.ui.error "\nQuitting..."
+        Bundler.ui.trace error
+      when Gem::InvalidSpecificationException
+        Bundler.ui.error error.message, wrap: true
+      when SystemExit
+      when *[defined?(Java::JavaLang::OutOfMemoryError) && Java::JavaLang::OutOfMemoryError].compact
+        Bundler.ui.error "\nYour JVM has run out of memory, and Bundler cannot continue. " \
+          "You can decrease the amount of memory Bundler needs by removing gems from your Gemfile, " \
+          "especially large gems. (Gems can be as large as hundreds of megabytes, and Bundler has to read those files!). " \
+          "Alternatively, you can increase the amount of memory the JVM is able to use by running Bundler with jruby -J-Xmx1024m -S bundle (JRuby defaults to 500MB)."
+      else request_issue_report_for(error)
+      end
+    end
+
+    def exit_status(error)
+      case error
+      when BundlerError then error.status_code
+      when Thor::Error then 15
+      when SystemExit then error.status
+      else 1
+      end
+    end
+
+    def request_issue_report_for(e)
+      Bundler.ui.error <<~EOS, nil, nil
+        --- ERROR REPORT TEMPLATE -------------------------------------------------------
+
+        ```
+        #{exception_message(e)}
+        ```
+
+        #{Bundler::Env.report}
+        --- TEMPLATE END ----------------------------------------------------------------
+
+      EOS
+
+      Bundler.ui.error "Unfortunately, an unexpected error occurred, and Bundler cannot continue."
+
+      Bundler.ui.error <<~EOS, nil, :yellow
+
+        First, try this link to see if there are any existing issue reports for this error:
+        #{issues_url(e)}
+
+        If there aren't any reports for this error yet, please fill in the new issue form located at #{new_issue_url}. Make sure to copy and paste the full output of this command under the "What happened instead?" section.
+      EOS
+    end
+
+    def exception_message(error)
+      message = serialized_exception_for(error)
+      cause = error.cause
+      return message unless cause
+
+      message + serialized_exception_for(cause)
+    end
+
+    def serialized_exception_for(e)
+      <<~EOS
+        #{e.class}: #{e.message}
+          #{e.backtrace&.join("\n          ")&.chomp}
+      EOS
+    end
+
+    def issues_url(exception)
+      message = exception.message.lines.first.tr(":", " ").chomp
+      message = message.split("-").first if exception.is_a?(Errno)
+      require "cgi/escape"
+      require "cgi/util" unless defined?(CGI::EscapeExt)
+      "https://github.com/ruby/rubygems/search?q=" \
+        "#{CGI.escape(message)}&type=Issues"
+    end
+
+    def new_issue_url
+      "https://github.com/ruby/rubygems/issues/new?labels=Bundler&template=bundler-related-issue.md"
+    end
+  end
+
+  def self.with_friendly_errors
+    FriendlyErrors.enable!
+    yield
+  rescue SignalException
+    raise
+  rescue Exception => e # rubocop:disable Lint/RescueException
+    raise if FriendlyErrors.disabled?
+
+    FriendlyErrors.log_error(e)
+    exit FriendlyErrors.exit_status(e)
+  end
+end
diff --git a/lib/bundler/gem_helper.rb b/lib/bundler/gem_helper.rb
new file mode 100644
index 0000000000..5ce0ef6280
--- /dev/null
+++ b/lib/bundler/gem_helper.rb
@@ -0,0 +1,237 @@
+# frozen_string_literal: true
+
+require_relative "../bundler"
+require "shellwords"
+
+module Bundler
+  class GemHelper
+    include Rake::DSL if defined? Rake::DSL
+
+    class << self
+      # set when install'd.
+      attr_accessor :instance
+
+      def install_tasks(opts = {})
+        new(opts[:dir], opts[:name]).install
+      end
+
+      def tag_prefix=(prefix)
+        instance.tag_prefix = prefix
+      end
+
+      def gemspec(&block)
+        gemspec = instance.gemspec
+        block&.call(gemspec)
+        gemspec
+      end
+    end
+
+    attr_reader :spec_path, :base, :gemspec
+
+    attr_writer :tag_prefix
+
+    def initialize(base = nil, name = nil)
+      @base = File.expand_path(base || SharedHelpers.pwd)
+      gemspecs = name ? [File.join(@base, "#{name}.gemspec")] : Gem::Util.glob_files_in_dir("{,*}.gemspec", @base)
+      raise "Unable to determine name from existing gemspec. Use :name => 'gemname' in #install_tasks to manually set it." unless gemspecs.size == 1
+      @spec_path = gemspecs.first
+      @gemspec = Bundler.load_gemspec(@spec_path)
+      @tag_prefix = ""
+    end
+
+    def install
+      built_gem_path = nil
+
+      desc "Build #{name}-#{version}.gem into the pkg directory."
+      task "build" do
+        built_gem_path = build_gem
+      end
+
+      desc "Generate SHA512 checksum of #{name}-#{version}.gem into the checksums directory."
+      task "build:checksum" => "build" do
+        build_checksum(built_gem_path)
+      end
+
+      desc "Build and install #{name}-#{version}.gem into system gems."
+      task "install" => "build" do
+        install_gem(built_gem_path)
+      end
+
+      desc "Build and install #{name}-#{version}.gem into system gems without network access."
+      task "install:local" => "build" do
+        install_gem(built_gem_path, :local)
+      end
+
+      desc "Create tag #{version_tag} and build and push #{name}-#{version}.gem to #{gem_push_host}\n" \
+           "To prevent publishing in RubyGems use `gem_push=no rake release`"
+      task "release", [:remote] => ["build", "release:guard_clean",
+                                    "release:source_control_push", "release:rubygem_push"] do
+      end
+
+      task "release:guard_clean" do
+        guard_clean
+      end
+
+      task "release:source_control_push", [:remote] do |_, args|
+        tag_version { git_push(args[:remote]) } unless already_tagged?
+      end
+
+      task "release:rubygem_push" => "build" do
+        rubygem_push(built_gem_path) if gem_push?
+      end
+
+      GemHelper.instance = self
+    end
+
+    def build_gem
+      file_name = nil
+      sh([*gem_command, "build", "-V", spec_path]) do
+        file_name = File.basename(built_gem_path)
+        SharedHelpers.filesystem_access(File.join(base, "pkg")) {|p| FileUtils.mkdir_p(p) }
+        FileUtils.mv(built_gem_path, "pkg")
+        Bundler.ui.confirm "#{name} #{version} built to pkg/#{file_name}."
+      end
+      File.join(base, "pkg", file_name)
+    end
+
+    def install_gem(built_gem_path = nil, local = false)
+      built_gem_path ||= build_gem
+      cmd = [*gem_command, "install", built_gem_path.to_s]
+      cmd << "--local" if local
+      sh(cmd)
+      Bundler.ui.confirm "#{name} (#{version}) installed."
+    end
+
+    def build_checksum(built_gem_path = nil)
+      built_gem_path ||= build_gem
+      SharedHelpers.filesystem_access(File.join(base, "checksums")) {|p| FileUtils.mkdir_p(p) }
+      file_name = "#{File.basename(built_gem_path)}.sha512"
+      require "digest/sha2"
+      checksum = ::Digest::SHA512.file(built_gem_path).hexdigest
+      target = File.join(base, "checksums", file_name)
+      File.write(target, checksum + "\n")
+      Bundler.ui.confirm "#{name} #{version} checksum written to checksums/#{file_name}."
+    end
+
+    protected
+
+    def rubygem_push(path)
+      cmd = [*gem_command, "push", path]
+      cmd << "--key" << gem_key if gem_key
+      cmd << "--host" << allowed_push_host if allowed_push_host
+      sh_with_input(cmd)
+      Bundler.ui.confirm "Pushed #{name} #{version} to #{gem_push_host}"
+    end
+
+    def built_gem_path
+      Gem::Util.glob_files_in_dir("#{name}-*.gem", base).sort_by {|f| File.mtime(f) }.last
+    end
+
+    def git_push(remote = nil)
+      remote ||= default_remote
+      sh("git push #{remote} refs/heads/#{current_branch}".shellsplit)
+      sh("git push #{remote} refs/tags/#{version_tag}".shellsplit)
+      Bundler.ui.confirm "Pushed git commits and release tag."
+    end
+
+    def default_remote
+      remote_for_branch, status = sh_with_status(%W[git config --get branch.#{current_branch}.remote])
+      return "origin" unless status.success?
+
+      remote_for_branch.strip
+    end
+
+    def current_branch
+      # We can replace this with `git branch --show-current` once we drop support for git < 2.22.0
+      sh(%w[git rev-parse --abbrev-ref HEAD]).gsub(%r{\Aheads/}, "").strip
+    end
+
+    def allowed_push_host
+      @gemspec.metadata["allowed_push_host"] if @gemspec.respond_to?(:metadata)
+    end
+
+    def gem_push_host
+      env_rubygems_host = ENV["RUBYGEMS_HOST"]
+      env_rubygems_host = nil if env_rubygems_host&.empty?
+
+      allowed_push_host || env_rubygems_host || "rubygems.org"
+    end
+
+    def already_tagged?
+      return false unless sh(%w[git tag]).split(/\n/).include?(version_tag)
+      Bundler.ui.confirm "Tag #{version_tag} has already been created."
+      true
+    end
+
+    def guard_clean
+      clean? && committed? || raise("There are files that need to be committed first.")
+    end
+
+    def clean?
+      sh_with_status(%w[git diff --exit-code])[1].success?
+    end
+
+    def committed?
+      sh_with_status(%w[git diff-index --quiet --cached HEAD])[1].success?
+    end
+
+    def tag_version
+      sh %W[git tag -m Version\ #{version} #{version_tag}]
+      Bundler.ui.confirm "Tagged #{version_tag}."
+      yield if block_given?
+    rescue RuntimeError
+      Bundler.ui.error "Untagging #{version_tag} due to error."
+      sh_with_status %W[git tag -d #{version_tag}]
+      raise
+    end
+
+    def version
+      gemspec.version
+    end
+
+    def version_tag
+      "#{@tag_prefix}v#{version}"
+    end
+
+    def name
+      gemspec.name
+    end
+
+    def sh_with_input(cmd)
+      Bundler.ui.debug(cmd)
+      SharedHelpers.chdir(base) do
+        abort unless Kernel.system(*cmd)
+      end
+    end
+
+    def sh(cmd, &block)
+      out, status = sh_with_status(cmd, &block)
+      unless status.success?
+        raise("Running `#{cmd.shelljoin}` failed with the following output:\n\n#{out}\n")
+      end
+      out
+    end
+
+    def sh_with_status(cmd, &block)
+      Bundler.ui.debug(cmd)
+      SharedHelpers.chdir(base) do
+        outbuf = IO.popen(cmd, err: [:child, :out], &:read)
+        status = $?
+        block&.call(outbuf) if status.success?
+        [outbuf, status]
+      end
+    end
+
+    def gem_key
+      Bundler.settings["gem.push_key"].to_s.downcase if Bundler.settings["gem.push_key"]
+    end
+
+    def gem_push?
+      !%w[n no nil false off 0].include?(ENV["gem_push"].to_s.downcase)
+    end
+
+    def gem_command
+      ENV["GEM_COMMAND"]&.shellsplit || ["gem"]
+    end
+  end
+end
diff --git a/lib/bundler/gem_tasks.rb b/lib/bundler/gem_tasks.rb
new file mode 100644
index 0000000000..bc725d3602
--- /dev/null
+++ b/lib/bundler/gem_tasks.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+require "rake/clean"
+CLOBBER.include "pkg"
+
+require_relative "gem_helper"
+Bundler::GemHelper.install_tasks
diff --git a/lib/bundler/gem_version_promoter.rb b/lib/bundler/gem_version_promoter.rb
new file mode 100644
index 0000000000..d64dbacfdb
--- /dev/null
+++ b/lib/bundler/gem_version_promoter.rb
@@ -0,0 +1,147 @@
+# frozen_string_literal: true
+
+module Bundler
+  # This class contains all of the logic for determining the next version of a
+  # Gem to update to based on the requested level (patch, minor, major).
+  # Primarily designed to work with Resolver which will provide it the list of
+  # available dependency versions as found in its index, before returning it to
+  # to the resolution engine to select the best version.
+  class GemVersionPromoter
+    attr_reader :level
+    attr_accessor :pre
+
+    # By default, strict is false, meaning every available version of a gem
+    # is returned from sort_versions. The order gives preference to the
+    # requested level (:patch, :minor, :major) but in complicated requirement
+    # cases some gems will by necessity be promoted past the requested level,
+    # or even reverted to older versions.
+    #
+    # If strict is set to true, the results from sort_versions will be
+    # truncated, eliminating any version outside the current level scope.
+    # This can lead to unexpected outcomes or even VersionConflict exceptions
+    # that report a version of a gem not existing for versions that indeed do
+    # existing in the referenced source.
+    attr_accessor :strict
+
+    # Creates a GemVersionPromoter instance.
+    #
+    # @return [GemVersionPromoter]
+    def initialize
+      @level = :major
+      @strict = false
+      @pre = false
+    end
+
+    # @param value [Symbol] One of three Symbols: :major, :minor or :patch.
+    def level=(value)
+      v = case value
+          when String, Symbol
+            value.to_sym
+      end
+
+      raise ArgumentError, "Unexpected level #{v}. Must be :major, :minor or :patch" unless [:major, :minor, :patch].include?(v)
+      @level = v
+    end
+
+    # Given a Resolver::Package and an Array of Specifications of available
+    # versions for a gem, this method will return the Array of Specifications
+    # sorted in an order to give preference to the current level (:major, :minor
+    # or :patch) when resolution is deciding what versions best resolve all
+    # dependencies in the bundle.
+    # @param package [Resolver::Package] The package being resolved.
+    # @param specs [Specification] An array of Specifications for the package.
+    # @return [Specification] A new instance of the Specification Array sorted.
+    def sort_versions(package, specs)
+      locked_version = package.locked_version
+
+      result = specs.sort do |a, b|
+        unless package.prerelease_specified? || pre?
+          a_pre = a.prerelease?
+          b_pre = b.prerelease?
+
+          next 1 if a_pre && !b_pre
+          next -1 if b_pre && !a_pre
+        end
+
+        if major? || locked_version.nil?
+          b <=> a
+        elsif either_version_older_than_locked?(a, b, locked_version)
+          b <=> a
+        elsif segments_do_not_match?(a, b, :major)
+          a <=> b
+        elsif !minor? && segments_do_not_match?(a, b, :minor)
+          a <=> b
+        else
+          b <=> a
+        end
+      end
+      post_sort(result, package.unlock?, locked_version)
+    end
+
+    # @return [bool] Convenience method for testing value of level variable.
+    def major?
+      level == :major
+    end
+
+    # @return [bool] Convenience method for testing value of level variable.
+    def minor?
+      level == :minor
+    end
+
+    # @return [bool] Convenience method for testing value of pre variable.
+    def pre?
+      pre == true
+    end
+
+    # Given a Resolver::Package and an Array of Specifications of available
+    # versions for a gem, this method will truncate the Array if strict
+    # is true. That means filtering out downgrades from the version currently
+    # locked, and filtering out upgrades that go past the selected level (major,
+    # minor, or patch).
+    # @param package [Resolver::Package] The package being resolved.
+    # @param specs [Specification] An array of Specifications for the package.
+    # @return [Specification] A new instance of the Specification Array
+    #   truncated.
+    def filter_versions(package, specs)
+      return specs unless strict
+
+      locked_version = package.locked_version
+      return specs if locked_version.nil? || major?
+
+      specs.select do |spec|
+        gsv = spec.version
+
+        must_match = minor? ? [0] : [0, 1]
+
+        all_match = must_match.all? {|idx| gsv.segments[idx] == locked_version.segments[idx] }
+        all_match && gsv >= locked_version
+      end
+    end
+
+    private
+
+    def either_version_older_than_locked?(a, b, locked_version)
+      a.version < locked_version || b.version < locked_version
+    end
+
+    def segments_do_not_match?(a, b, level)
+      index = [:major, :minor].index(level)
+      a.segments[index] != b.segments[index]
+    end
+
+    # Specific version moves can't always reliably be done during sorting
+    # as not all elements are compared against each other.
+    def post_sort(result, unlock, locked_version)
+      if unlock || locked_version.nil?
+        result
+      else
+        move_version_to_beginning(result, locked_version)
+      end
+    end
+
+    def move_version_to_beginning(result, version)
+      move, keep = result.partition {|s| s.version.to_s == version.to_s }
+      move.concat(keep)
+    end
+  end
+end
diff --git a/lib/bundler/index.rb b/lib/bundler/index.rb
new file mode 100644
index 0000000000..9aef2dfa12
--- /dev/null
+++ b/lib/bundler/index.rb
@@ -0,0 +1,203 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Index
+    include Enumerable
+
+    def self.build
+      i = new
+      yield i
+      i
+    end
+
+    attr_reader :specs, :duplicates, :sources
+    protected :specs, :duplicates
+
+    RUBY = "ruby"
+    NULL = "\0"
+
+    def initialize
+      @sources = []
+      @cache = {}
+      @specs = {}
+      @duplicates = {}
+    end
+
+    def initialize_copy(o)
+      @sources = o.sources.dup
+      @cache = {}
+      @specs = {}
+      @duplicates = {}
+
+      o.specs.each do |name, hash|
+        @specs[name] = hash.dup
+      end
+      o.duplicates.each do |name, array|
+        @duplicates[name] = array.dup
+      end
+    end
+
+    def inspect
+      "#<#{self.class}:0x#{object_id} sources=#{sources.map(&:inspect)} specs.size=#{specs.size}>"
+    end
+
+    def empty?
+      each { return false }
+      true
+    end
+
+    # Search this index's specs, and any source indexes that this index knows
+    # about, returning all of the results.
+    def search(query)
+      results = local_search(query)
+      return results unless @sources.any?
+
+      @sources.each do |source|
+        results = safe_concat(results, source.search(query))
+      end
+      results.uniq!(&:full_name) unless results.empty? # avoid modifying frozen EMPTY_SEARCH
+      results
+    end
+
+    alias_method :[], :search
+
+    def local_search(query)
+      case query
+      when Gem::Specification, RemoteSpecification, LazySpecification, EndpointSpecification then search_by_spec(query)
+      when String then specs_by_name(query)
+      when Array then specs_by_name_and_version(*query)
+      else
+        raise "You can't search for a #{query.inspect}."
+      end
+    end
+
+    def add(spec)
+      (@specs[spec.name] ||= {}).store(spec.full_name, spec)
+    end
+    alias_method :<<, :add
+
+    def each(&blk)
+      return enum_for(:each) unless blk
+      specs.values.each do |spec_sets|
+        spec_sets.values.each(&blk)
+      end
+      sources.each {|s| s.each(&blk) }
+      self
+    end
+
+    def spec_names
+      names = specs.keys + sources.map(&:spec_names)
+      names.uniq!
+      names
+    end
+
+    def unmet_dependency_names
+      dependency_names.select do |name|
+        search(name).empty?
+      end
+    end
+
+    def dependency_names
+      names = []
+      each do |spec|
+        spec.dependencies.each do |dep|
+          next if dep.type == :development
+          names << dep.name
+        end
+      end
+      names.uniq
+    end
+
+    # Combines indexes proritizing existing specs, like `Hash#reverse_merge!`
+    # Duplicate specs found in `other` are stored in `@duplicates`.
+    def use(other)
+      return unless other
+      other.each do |spec|
+        exist?(spec) ? add_duplicate(spec) : add(spec)
+      end
+      self
+    end
+
+    # Combines indexes proritizing specs from `other`, like `Hash#merge!`
+    # Duplicate specs found in `self` are saved in `@duplicates`.
+    def merge!(other)
+      return unless other
+      other.each do |spec|
+        if existing = find_by_spec(spec)
+          unless dependencies_eql?(existing, spec)
+            Bundler.ui.warn "Local specification for #{spec.full_name} has different dependencies than the remote gem, ignoring it"
+            next
+          end
+
+          add_duplicate(existing)
+        end
+        add spec
+      end
+      self
+    end
+
+    def size
+      @sources.inject(@specs.size) do |size, source|
+        size += source.size
+      end
+    end
+
+    # Whether all the specs in self are in other
+    def subset?(other)
+      all? do |spec|
+        other_spec = other[spec].first
+        other_spec && dependencies_eql?(spec, other_spec) && spec.source == other_spec.source
+      end
+    end
+
+    def dependencies_eql?(spec, other_spec)
+      deps       = spec.runtime_dependencies
+      other_deps = other_spec.runtime_dependencies
+      deps.sort == other_deps.sort
+    end
+
+    def add_source(index)
+      raise ArgumentError, "Source must be an index, not #{index.class}" unless index.is_a?(Index)
+      @sources << index
+      @sources.uniq! # need to use uniq! here instead of checking for the item before adding
+    end
+
+    private
+
+    def safe_concat(a, b)
+      return a if b.empty?
+      return b if a.empty?
+      a.concat(b)
+    end
+
+    def add_duplicate(spec)
+      (@duplicates[spec.name] ||= []) << spec
+    end
+
+    def specs_by_name_and_version(name, version)
+      results = @specs[name]&.values
+      return EMPTY_SEARCH unless results
+      results.select! {|spec| spec.version == version }
+      results
+    end
+
+    def specs_by_name(name)
+      @specs[name]&.values || EMPTY_SEARCH
+    end
+
+    EMPTY_SEARCH = [].freeze
+
+    def search_by_spec(spec)
+      spec = find_by_spec(spec)
+      spec ? [spec] : EMPTY_SEARCH
+    end
+
+    def find_by_spec(spec)
+      @specs[spec.name]&.fetch(spec.full_name, nil)
+    end
+
+    def exist?(spec)
+      @specs[spec.name]&.key?(spec.full_name)
+    end
+  end
+end
diff --git a/lib/bundler/injector.rb b/lib/bundler/injector.rb
new file mode 100644
index 0000000000..6aa9179024
--- /dev/null
+++ b/lib/bundler/injector.rb
@@ -0,0 +1,284 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Injector
+    INJECTED_GEMS = "injected gems"
+
+    def self.inject(new_deps, options = {})
+      injector = new(new_deps, options)
+      injector.inject(Bundler.default_gemfile, Bundler.default_lockfile)
+    end
+
+    def self.remove(gems, options = {})
+      injector = new(gems, options)
+      injector.remove(Bundler.default_gemfile, Bundler.default_lockfile)
+    end
+
+    def initialize(deps, options = {})
+      @deps = deps
+      @options = options
+    end
+
+    # @param [Pathname] gemfile_path The Gemfile in which to inject the new dependency.
+    # @param [Pathname] lockfile_path The lockfile in which to inject the new dependency.
+    # @return [Array]
+    def inject(gemfile_path, lockfile_path)
+      Bundler.definition.ensure_equivalent_gemfile_and_lockfile(true)
+
+      # temporarily unfreeze
+      Bundler.settings.temporary(deployment: false, frozen: false) do
+        # evaluate the Gemfile we have now
+        builder = Dsl.new
+        builder.eval_gemfile(gemfile_path)
+
+        # don't inject any gems that are already in the Gemfile
+        @deps -= builder.dependencies
+
+        # add new deps to the end of the in-memory Gemfile
+        # Set conservative versioning to false because
+        # we want to let the resolver resolve the version first
+        builder.eval_gemfile(INJECTED_GEMS, build_gem_lines(false)) if @deps.any?
+
+        # resolve to see if the new deps broke anything
+        @definition = builder.to_definition(lockfile_path, {})
+        @definition.remotely!
+
+        # since nothing broke, we can add those gems to the gemfile
+        append_to(gemfile_path, build_gem_lines(@options[:conservative_versioning])) if @deps.any?
+
+        # since we resolved successfully, write out the lockfile
+        @definition.lock
+
+        # invalidate the cached Bundler.definition
+        Bundler.reset_paths!
+
+        # return an array of the deps that we added
+        @deps
+      end
+    end
+
+    # @param [Pathname] gemfile_path The Gemfile from which to remove dependencies.
+    # @param [Pathname] lockfile_path The lockfile from which to remove dependencies.
+    # @return [Array]
+    def remove(gemfile_path, lockfile_path)
+      # remove gems from each gemfiles we have
+      Bundler.definition.gemfiles.each do |path|
+        deps = remove_deps(path)
+
+        show_warning("No gems were removed from the gemfile.") if deps.empty?
+
+        deps.each {|dep| Bundler.ui.confirm "#{SharedHelpers.pretty_dependency(dep)} was removed." }
+      end
+
+      # Invalidate the cached Bundler.definition.
+      # This prevents e.g. `bundle remove ...` from using outdated information.
+      Bundler.reset_paths!
+    end
+
+    private
+
+    def conservative_version(spec)
+      version = spec.version
+      return ">= 0" if version.nil?
+      seg_end_index = version >= Gem::Version.new("1.0") ? 1 : 2
+
+      prerelease_suffix = version.to_s.delete_prefix(version.release.to_s) if version.prerelease?
+      "#{version_prefix}#{version.segments[0..seg_end_index].join(".")}#{prerelease_suffix}"
+    end
+
+    def version_prefix
+      if @options[:strict]
+        "= "
+      elsif @options[:pessimistic]
+        "~> "
+      else
+        ">= "
+      end
+    end
+
+    def build_gem_lines(conservative_versioning)
+      @deps.map do |d|
+        name = d.name.dump
+
+        requirement = if conservative_versioning
+          ", \"#{conservative_version(@definition.specs[d.name][0])}\""
+        else
+          ", #{d.requirement.as_list.map(&:dump).join(", ")}"
+        end
+
+        if d.groups != Array(:default)
+          group = d.groups.size == 1 ? ", group: #{d.groups.first.inspect}" : ", groups: #{d.groups.inspect}"
+        end
+
+        source = ", source: \"#{d.source}\"" unless d.source.nil?
+        path = ", path: \"#{d.path}\"" unless d.path.nil?
+        git = ", git: \"#{d.git}\"" unless d.git.nil?
+        github = ", github: \"#{d.github}\"" unless d.github.nil?
+        branch = ", branch: \"#{d.branch}\"" unless d.branch.nil?
+        ref = ", ref: \"#{d.ref}\"" unless d.ref.nil?
+        glob = ", glob: \"#{d.glob}\"" unless d.glob.nil?
+        require_path = ", require: #{convert_autorequire(d.autorequire)}" unless d.autorequire.nil?
+
+        %(gem #{name}#{requirement}#{group}#{source}#{path}#{git}#{github}#{branch}#{ref}#{glob}#{require_path})
+      end.join("\n")
+    end
+
+    def append_to(gemfile_path, new_gem_lines)
+      gemfile_path.open("a") do |f|
+        f.puts
+        f.puts new_gem_lines
+      end
+    end
+
+    # evaluates a gemfile to remove the specified gem
+    # from it.
+    def remove_deps(gemfile_path)
+      initial_gemfile = File.readlines(gemfile_path)
+
+      Bundler.ui.info "Removing gems from #{gemfile_path}"
+
+      # evaluate the Gemfile we have
+      builder = Dsl.new
+      builder.eval_gemfile(gemfile_path)
+
+      removed_deps = remove_gems_from_dependencies(builder, @deps, gemfile_path)
+
+      # abort the operation if no gems were removed
+      # no need to operate on gemfile further
+      return [] if removed_deps.empty?
+
+      cleaned_gemfile = remove_gems_from_gemfile(@deps, gemfile_path)
+
+      SharedHelpers.write_to_gemfile(gemfile_path, cleaned_gemfile)
+
+      # check for errors
+      # including extra gems being removed
+      # or some gems not being removed
+      # and return the actual removed deps
+      cross_check_for_errors(gemfile_path, builder.dependencies, removed_deps, initial_gemfile)
+    end
+
+    # @param [Dsl]      builder Dsl object of current Gemfile.
+    # @param [Array]    gems Array of names of gems to be removed.
+    # @param [Pathname] gemfile_path Path of the Gemfile.
+    # @return [Array]   Array of removed dependencies.
+    def remove_gems_from_dependencies(builder, gems, gemfile_path)
+      removed_deps = []
+
+      gems.each do |gem_name|
+        deleted_dep = builder.dependencies.find {|d| d.name == gem_name }
+
+        if deleted_dep.nil?
+          raise GemfileError, "`#{gem_name}` is not specified in #{gemfile_path} so it could not be removed."
+        end
+
+        builder.dependencies.delete(deleted_dep)
+
+        removed_deps << deleted_dep
+      end
+
+      removed_deps
+    end
+
+    # @param [Array] gems            Array of names of gems to be removed.
+    # @param [Pathname] gemfile_path The Gemfile from which to remove dependencies.
+    def remove_gems_from_gemfile(gems, gemfile_path)
+      patterns = /gem\s+(['"])#{Regexp.union(gems)}\1|gem\s*\((['"])#{Regexp.union(gems)}\2.*\)/
+      new_gemfile = []
+      multiline_removal = false
+      File.readlines(gemfile_path).each do |line|
+        match_data = line.match(patterns)
+        if match_data && is_not_within_comment?(line, match_data)
+          multiline_removal = line.rstrip.end_with?(",")
+          # skip lines which match the regex
+          next
+        end
+
+        # skip followup lines until line does not end with ','
+        new_gemfile << line unless multiline_removal
+        multiline_removal = line.rstrip.end_with?(",") if multiline_removal
+      end
+
+      # remove line \n and append them with other strings
+      new_gemfile.each_with_index do |_line, index|
+        if new_gemfile[index + 1] == "\n"
+          new_gemfile[index] += new_gemfile[index + 1]
+          new_gemfile.delete_at(index + 1)
+        end
+      end
+
+      %w[group source env install_if].each {|block| remove_nested_blocks(new_gemfile, block) }
+
+      new_gemfile.join.chomp
+    end
+
+    # @param [String] line          Individual line of gemfile content.
+    # @param [MatchData] match_data Data about Regex match.
+    def is_not_within_comment?(line, match_data)
+      match_start_index = match_data.offset(0).first
+      !line[0..match_start_index].include?("#")
+    end
+
+    # @param [Array] gemfile       Array of gemfile contents.
+    # @param [String] block_name   Name of block name to look for.
+    def remove_nested_blocks(gemfile, block_name)
+      nested_blocks = 0
+
+      # count number of nested blocks
+      gemfile.each_with_index {|line, index| nested_blocks += 1 if !gemfile[index + 1].nil? && gemfile[index + 1].include?(block_name) && line.include?(block_name) }
+
+      while nested_blocks >= 0
+        nested_blocks -= 1
+
+        gemfile.each_with_index do |line, index|
+          next unless !line.nil? && line.strip.start_with?(block_name)
+          if /^\s*end\s*$/.match?(gemfile[index + 1])
+            gemfile[index] = nil
+            gemfile[index + 1] = nil
+          end
+        end
+
+        gemfile.compact!
+      end
+    end
+
+    # @param [Pathname] gemfile_path   The Gemfile from which to remove dependencies.
+    # @param [Array] original_deps     Array of original dependencies.
+    # @param [Array] removed_deps      Array of removed dependencies.
+    # @param [Array] initial_gemfile   Contents of original Gemfile before any operation.
+    def cross_check_for_errors(gemfile_path, original_deps, removed_deps, initial_gemfile)
+      # evaluate the new gemfile to look for any failure cases
+      builder = Dsl.new
+      builder.eval_gemfile(gemfile_path)
+
+      # record gems which were removed but not requested
+      extra_removed_gems = original_deps - builder.dependencies
+
+      # if some extra gems were removed then raise error
+      # and revert Gemfile to original
+      unless extra_removed_gems.empty?
+        SharedHelpers.write_to_gemfile(gemfile_path, initial_gemfile.join)
+
+        raise InvalidOption, "Gems could not be removed. #{extra_removed_gems.join(", ")} would also have been removed. Bundler cannot continue."
+      end
+
+      # record gems which could not be removed due to some reasons
+      errored_deps = builder.dependencies.select {|d| d.gemfile == gemfile_path } & removed_deps.select {|d| d.gemfile == gemfile_path }
+
+      show_warning "#{errored_deps.map(&:name).join(", ")} could not be removed." unless errored_deps.empty?
+
+      # return actual removed dependencies
+      removed_deps - errored_deps
+    end
+
+    def show_warning(message)
+      Bundler.ui.info Bundler.ui.add_color(message, :yellow)
+    end
+
+    def convert_autorequire(autorequire)
+      autorequire = autorequire.first
+      return autorequire if autorequire == "false"
+      autorequire.inspect
+    end
+  end
+end
diff --git a/lib/bundler/inline.rb b/lib/bundler/inline.rb
new file mode 100644
index 0000000000..a1b8e0475e
--- /dev/null
+++ b/lib/bundler/inline.rb
@@ -0,0 +1,146 @@
+# frozen_string_literal: true
+
+# Allows for declaring a Gemfile inline in a ruby script, installing any gems
+# that aren't already installed on the user's system.
+#
+# @note Every gem that is specified in this 'Gemfile' will be `require`d, as if
+#       the user had manually called `Bundler.require`. To avoid a requested gem
+#       being automatically required, add the `:require => false` option to the
+#       `gem` dependency declaration.
+#
+# @param force_latest_compatible [Boolean] Force installing the *latest*
+#                                          compatible versions of the gems,
+#                                          even if compatible versions are
+#                                          already installed locally.
+#                                          This also logs output if the
+#                                          `:quiet` option is not set.
+#                                          Defaults to `false`.
+#
+# @param gemfile [Proc]    a block that is evaluated as a `Gemfile`.
+#
+# @example Using an inline Gemfile
+#
+#          #!/usr/bin/env ruby
+#
+#          require 'bundler/inline'
+#
+#          gemfile do
+#            source 'https://rubygems.org'
+#            gem 'json', require: false
+#            gem 'nap', require: 'rest'
+#            gem 'cocoapods', '~> 0.34.1'
+#          end
+#
+#          puts Pod::VERSION # => "0.34.4"
+#
+def gemfile(force_latest_compatible = false, options = {}, &gemfile)
+  require_relative "../bundler"
+  Bundler.reset!
+
+  opts = options.dup
+  ui = opts.delete(:ui) { Bundler::UI::Shell.new }
+  ui.level = "silent" if opts.delete(:quiet) || !force_latest_compatible
+  Bundler.ui = ui
+  raise ArgumentError, "Unknown options: #{opts.keys.join(", ")}" unless opts.empty?
+
+  old_gemfile = ENV["BUNDLE_GEMFILE"]
+  old_lockfile = ENV["BUNDLE_LOCKFILE"]
+
+  Bundler.unbundle_env!
+
+  begin
+    Bundler.instance_variable_set(:@bundle_path, Pathname.new(Gem.dir))
+    Bundler::SharedHelpers.set_env "BUNDLE_GEMFILE", "Gemfile"
+    Bundler::SharedHelpers.set_env "BUNDLE_LOCKFILE", "Gemfile.lock"
+
+    Bundler::Plugin.gemfile_install(&gemfile) if Bundler.settings[:plugins]
+    builder = Bundler::Dsl.new
+    builder.instance_eval(&gemfile)
+
+    Bundler.settings.temporary(deployment: false, frozen: false) do
+      definition = builder.to_definition(nil, true)
+      definition.validate_runtime!
+
+      if force_latest_compatible || definition.missing_specs?
+        do_install = -> do
+          Bundler.settings.temporary(inline: true, no_install: false) do
+            installer = Bundler::Installer.install(Bundler.root, definition, system: true)
+            installer.post_install_messages.each do |name, message|
+              Bundler.ui.info "Post-install message from #{name}:\n#{message}"
+            end
+          end
+        end
+
+        # When possible we do the install in a subprocess because to install
+        # gems we need to require some default gems like `securerandom` etc
+        # which may later conflict with the Gemfile requirements.
+        installed_in_fork = false
+        if Process.respond_to?(:fork)
+          Gem.load_yaml # Avoid NameError on Ruby 3.2's safe_yaml.rb after Gem::Specification.reset
+          _, status = Process.waitpid2(Process.fork do
+                                         $VERBOSE = nil
+                                         do_install.call end)
+          exit(status.exitstatus || status.to_i) unless status.success?
+
+          installed_in_fork = true
+
+          Bundler.reset!
+          Gem::Specification.reset
+          Bundler.instance_variable_set(:@bundle_path, Pathname.new(Gem.dir))
+
+          builder = Bundler::Dsl.new
+          builder.instance_eval(&gemfile)
+          builder.check_primary_source_safety
+
+          definition = builder.to_definition(nil, true)
+          definition.validate_runtime!
+        else
+          do_install.call
+        end
+      end
+
+      configure_forked_definition = ->(d) do
+        d.sources.rubygems_sources.each(&:remote!)
+        d.sources.git_sources.each do |source|
+          source.cached!
+          source.instance_variable_set(:@copied, true)
+        end
+        def d.lock(*); end
+      end
+      configure_forked_definition.call(definition) if installed_in_fork
+
+      begin
+        runtime = Bundler::Runtime.new(nil, definition).setup
+      rescue Gem::LoadError => e
+        name = e.name
+        version = e.requirement.requirements.first[1]
+        activated_version = Gem.loaded_specs[name].version
+
+        Bundler.ui.info \
+          "The #{name} gem was resolved to #{version}, but #{activated_version} was activated by Bundler while installing it, causing a conflict. " \
+          "Bundler will now retry resolving with #{activated_version} instead."
+
+        builder.dependencies.delete_if {|d| d.name == name }
+        builder.instance_eval { gem name, activated_version }
+        definition = builder.to_definition(nil, true)
+        configure_forked_definition.call(definition) if installed_in_fork
+
+        retry
+      end
+
+      runtime.require
+    end
+  ensure
+    if old_gemfile
+      ENV["BUNDLE_GEMFILE"] = old_gemfile
+    else
+      ENV["BUNDLE_GEMFILE"] = ""
+    end
+
+    if old_lockfile
+      ENV["BUNDLE_LOCKFILE"] = old_lockfile
+    else
+      ENV["BUNDLE_LOCKFILE"] = ""
+    end
+  end
+end
diff --git a/lib/bundler/installer.rb b/lib/bundler/installer.rb
new file mode 100644
index 0000000000..87d9a75627
--- /dev/null
+++ b/lib/bundler/installer.rb
@@ -0,0 +1,236 @@
+# frozen_string_literal: true
+
+require_relative "worker"
+require_relative "installer/parallel_installer"
+require_relative "installer/standalone"
+require_relative "installer/gem_installer"
+
+module Bundler
+  class Installer
+    attr_reader :post_install_messages, :definition
+
+    # Begins the installation process for Bundler.
+    # For more information see the #run method on this class.
+    def self.install(root, definition, options = {})
+      installer = new(root, definition)
+      Plugin.hook(Plugin::Events::GEM_BEFORE_INSTALL_ALL, definition.dependencies)
+      installer.run(options)
+      Plugin.hook(Plugin::Events::GEM_AFTER_INSTALL_ALL, definition.dependencies)
+      installer
+    end
+
+    def initialize(root, definition)
+      @root = root
+      @definition = definition
+      @post_install_messages = {}
+    end
+
+    # Runs the install procedures for a specific Gemfile.
+    #
+    # Firstly, this method will check to see if `Bundler.bundle_path` exists
+    # and if not then Bundler will create the directory. This is usually the same
+    # location as RubyGems which typically is the `~/.gem` directory
+    # unless other specified.
+    #
+    # Secondly, it checks if Bundler has been configured to be "frozen".
+    # Frozen ensures that the Gemfile and the Gemfile.lock file are matching.
+    # This stops a situation where a developer may update the Gemfile but may not run
+    # `bundle install`, which leads to the Gemfile.lock file not being correctly updated.
+    # If this file is not correctly updated then any other developer running
+    # `bundle install` will potentially not install the correct gems.
+    #
+    # Thirdly, Bundler checks if there are any dependencies specified in the Gemfile.
+    # If there are no dependencies specified then Bundler returns a warning message stating
+    # so and this method returns.
+    #
+    # Fourthly, Bundler checks if the Gemfile.lock exists, and if so
+    # then proceeds to set up a definition based on the Gemfile and the Gemfile.lock.
+    # During this step Bundler will also download information about any new gems
+    # that are not in the Gemfile.lock and resolve any dependencies if needed.
+    #
+    # Fifthly, Bundler resolves the dependencies either through a cache of gems or by remote.
+    # This then leads into the gems being installed, along with stubs for their executables,
+    # but only if the --binstubs option has been passed or Bundler.options[:bin] has been set
+    # earlier.
+    #
+    # Sixthly, a new Gemfile.lock is created from the installed gems to ensure that the next time
+    # that a user runs `bundle install` they will receive any updates from this process.
+    #
+    # Finally, if the user has specified the standalone flag, Bundler will generate the needed
+    # require paths and save them in a `setup.rb` file. See `bundle standalone --help` for more
+    # information.
+    def run(options)
+      Bundler.create_bundle_path
+
+      ProcessLock.lock do
+        # Invalidate any stale gem specification cache from before we acquired the lock.
+        # Another process may have installed gems while we were waiting.
+        Gem::Specification.reset
+        @definition.sources.clear_cache
+
+        @definition.ensure_equivalent_gemfile_and_lockfile(options[:deployment])
+
+        if @definition.dependencies.empty?
+          Bundler.ui.warn "The Gemfile specifies no dependencies"
+          lock
+          return
+        end
+
+        if @definition.setup_domain!(options)
+          ensure_specs_are_compatible!
+          load_plugins
+        end
+        install(options)
+
+        Gem::Specification.reset # invalidate gem specification cache so that installed gems are immediately available
+
+        lock
+        Standalone.new(options[:standalone], @definition).generate if options[:standalone]
+      end
+    end
+
+    def generate_bundler_executable_stubs(spec, options = {})
+      if spec.name == "bundler"
+        Bundler.ui.warn "Bundler itself does not use binstubs because its version is selected by RubyGems"
+        return
+      end
+
+      if options[:binstubs_cmd] && spec.executables.empty?
+        options = {}
+        spec.runtime_dependencies.each do |dep|
+          bins = @definition.specs[dep].first.executables
+          options[dep.name] = bins unless bins.empty?
+        end
+        if options.any?
+          Bundler.ui.warn "#{spec.name} has no executables, but you may want " \
+            "one from a gem it depends on."
+          options.each {|name, bins| Bundler.ui.warn "  #{name} has: #{bins.join(", ")}" }
+        else
+          Bundler.ui.warn "There are no executables for the gem #{spec.name}."
+        end
+        return
+      end
+
+      # double-assignment to avoid warnings about variables that will be used by ERB
+      bin_path = Bundler.bin_path
+      bin_path = bin_path
+      relative_gemfile_path = Bundler.default_gemfile.relative_path_from(bin_path)
+      relative_gemfile_path = relative_gemfile_path
+      ruby_command = Thor::Util.ruby_command
+      ruby_command = ruby_command
+      template_path = File.expand_path("templates/Executable", __dir__)
+      template = File.read(template_path)
+
+      exists = []
+      spec.executables.each do |executable|
+        binstub_path = "#{bin_path}/#{executable}"
+        if File.exist?(binstub_path) && !options[:force]
+          exists << executable
+          next
+        end
+
+        mode = Gem.win_platform? ? "wb:UTF-8" : "w"
+        require "erb"
+        content = ERB.new(template, trim_mode: "-").result(binding)
+
+        File.write(binstub_path, content, mode: mode, perm: 0o777 & ~File.umask)
+        if Gem.win_platform? || options[:all_platforms]
+          prefix = "@ruby -x \"%~f0\" %*\n@exit /b %ERRORLEVEL%\n\n"
+          File.write("#{binstub_path}.cmd", prefix + content, mode: mode)
+        end
+      end
+
+      if options[:binstubs_cmd] && exists.any?
+        case exists.size
+        when 1
+          Bundler.ui.warn "Skipped #{exists[0]} since it already exists."
+        when 2
+          Bundler.ui.warn "Skipped #{exists.join(" and ")} since they already exist."
+        else
+          items = exists[0...-1].empty? ? nil : exists[0...-1].join(", ")
+          skipped = [items, exists[-1]].compact.join(" and ")
+          Bundler.ui.warn "Skipped #{skipped} since they already exist."
+        end
+        Bundler.ui.warn "If you want to overwrite skipped stubs, use --force."
+      end
+    end
+
+    def generate_standalone_bundler_executable_stubs(spec, options = {})
+      # double-assignment to avoid warnings about variables that will be used by ERB
+      bin_path = Bundler.bin_path
+      unless path = Bundler.settings[:path]
+        raise "Can't standalone without an explicit path set"
+      end
+      standalone_path = Bundler.root.join(path).relative_path_from(bin_path)
+      standalone_path = standalone_path
+      template = File.read(File.expand_path("templates/Executable.standalone", __dir__))
+      ruby_command = Thor::Util.ruby_command
+      ruby_command = ruby_command
+
+      spec.executables.each do |executable|
+        next if executable == "bundle"
+        executable_path = Pathname(spec.full_gem_path).join(spec.bindir, executable).relative_path_from(bin_path)
+        executable_path = executable_path
+
+        mode = Gem.win_platform? ? "wb:UTF-8" : "w"
+        require "erb"
+        content = ERB.new(template, trim_mode: "-").result(binding)
+
+        File.write("#{bin_path}/#{executable}", content, mode: mode, perm: 0o755)
+        if Gem.win_platform? || options[:all_platforms]
+          prefix = "@ruby -x \"%~f0\" %*\n@exit /b %ERRORLEVEL%\n\n"
+          File.write("#{bin_path}/#{executable}.cmd", prefix + content, mode: mode)
+        end
+      end
+    end
+
+    private
+
+    # the order that the resolver provides is significant, since
+    # dependencies might affect the installation of a gem.
+    # that said, it's a rare situation (other than rake), and parallel
+    # installation is SO MUCH FASTER. so we let people opt in.
+    def install(options)
+      standalone = options[:standalone]
+      force = options[:force]
+      local = options[:local] || options[:"prefer-local"]
+      jobs = Bundler.settings.installation_parallelization
+      spec_installations = ParallelInstaller.call(self, @definition.specs, jobs, standalone, force, local: local)
+      spec_installations.each do |installation|
+        post_install_messages[installation.name] = installation.post_install_message if installation.has_post_install_message?
+      end
+    end
+
+    def load_plugins
+      Gem.load_plugins
+
+      requested_path_gems = @definition.specs.select {|s| s.source.is_a?(Source::Path) }
+      path_plugin_files = requested_path_gems.flat_map do |spec|
+        spec.matches_for_glob("rubygems_plugin#{Bundler.rubygems.suffix_pattern}")
+      rescue TypeError
+        error_message = "#{spec.name} #{spec.version} has an invalid gemspec"
+        raise Gem::InvalidSpecificationException, error_message
+      end
+      Gem.load_plugin_files(path_plugin_files)
+      Gem.load_env_plugins
+    end
+
+    def ensure_specs_are_compatible!
+      overrides = @definition.overrides
+      @definition.specs.each do |spec|
+        unless spec.matches_current_ruby_with_overrides?(overrides)
+          raise InstallError, "#{spec.full_name} requires ruby version #{spec.required_ruby_version}, " \
+            "which is incompatible with the current version, #{Gem.ruby_version}"
+        end
+        unless spec.matches_current_rubygems_with_overrides?(overrides)
+          raise InstallError, "#{spec.full_name} requires rubygems version #{spec.required_rubygems_version}, " \
+            "which is incompatible with the current version, #{Gem.rubygems_version}"
+        end
+      end
+    end
+
+    def lock
+      @definition.lock
+    end
+  end
+end
diff --git a/lib/bundler/installer/gem_installer.rb b/lib/bundler/installer/gem_installer.rb
new file mode 100644
index 0000000000..f3b43c31ee
--- /dev/null
+++ b/lib/bundler/installer/gem_installer.rb
@@ -0,0 +1,88 @@
+# frozen_string_literal: true
+
+module Bundler
+  class GemInstaller
+    attr_reader :spec, :standalone, :worker, :force, :local, :installer
+
+    def initialize(spec, installer, standalone = false, worker = 0, force = false, local = false)
+      @spec = spec
+      @installer = installer
+      @standalone = standalone
+      @worker = worker
+      @force = force
+      @local = local
+    end
+
+    def install_from_spec
+      post_install_message = install
+      Bundler.ui.debug "#{worker}:  #{spec.name} (#{spec.version}) from #{spec.loaded_from}"
+      [true, post_install_message]
+    rescue Bundler::InstallHookError, Bundler::SecurityError, Bundler::APIResponseMismatchError, Bundler::InsecureInstallPathError
+      raise
+    rescue Errno::ENOSPC
+      [false, out_of_space_message]
+    rescue Bundler::BundlerError, Gem::InstallError => e
+      [false, specific_failure_message(e)]
+    end
+
+    def download
+      spec.source.download(
+        spec,
+        force: force,
+        local: local,
+        build_args: Array(spec_settings),
+        previous_spec: previous_spec,
+      )
+
+      [true, nil]
+    rescue Bundler::BundlerError => e
+      [false, specific_failure_message(e)]
+    end
+
+    private
+
+    def specific_failure_message(e)
+      message = "#{e.class}: #{e.message}\n"
+      message += "  " + e.backtrace.join("\n  ") + "\n\n"
+      message = message.lines.first + Bundler.ui.add_color(message.lines.drop(1).join, :clear)
+      message + Bundler.ui.add_color(failure_message, :red)
+    end
+
+    def failure_message
+      install_error_message
+    end
+
+    def install_error_message
+      "An error occurred while installing #{spec.name} (#{spec.version}), and Bundler cannot continue."
+    end
+
+    def spec_settings
+      # Fetch the build settings, if there are any
+      if settings = Bundler.settings["build.#{spec.name}"]
+        require "shellwords"
+        Shellwords.shellsplit(settings)
+      end
+    end
+
+    def install
+      spec.source.install(
+        spec,
+        force: force,
+        local: local,
+        build_args: Array(spec_settings),
+        previous_spec: previous_spec,
+      )
+    end
+
+    def previous_spec
+      locked_gems = installer.definition.locked_gems
+      return unless locked_gems
+
+      locked_gems.specs.find {|s| s.name == spec.name }
+    end
+
+    def out_of_space_message
+      "#{install_error_message}\nYour disk is out of space. Free some space to be able to install your bundle."
+    end
+  end
+end
diff --git a/lib/bundler/installer/parallel_installer.rb b/lib/bundler/installer/parallel_installer.rb
new file mode 100644
index 0000000000..fef326ed0a
--- /dev/null
+++ b/lib/bundler/installer/parallel_installer.rb
@@ -0,0 +1,241 @@
+# frozen_string_literal: true
+
+require_relative "../worker"
+require_relative "gem_installer"
+
+module Bundler
+  class ParallelInstaller
+    class SpecInstallation
+      attr_accessor :spec, :name, :full_name, :post_install_message, :state, :error, :dependencies
+      def initialize(spec)
+        @spec = spec
+        @name = spec.name
+        @full_name = spec.full_name
+        @state = :none
+        @post_install_message = ""
+        @error = nil
+      end
+
+      def installed?
+        state == :installed
+      end
+
+      def enqueued?
+        state == :enqueued
+      end
+
+      def enqueue_with_priority?
+        state == :installable && spec.extensions.any?
+      end
+
+      def failed?
+        state == :failed
+      end
+
+      def ready_to_enqueue?
+        state == :none
+      end
+
+      def ready_to_install?(installed_specs)
+        return false unless state == :downloaded
+
+        spec.extensions.none? || dependencies_installed?(installed_specs)
+      end
+
+      def has_post_install_message?
+        !post_install_message.empty?
+      end
+
+      # Recursively checks that all dependencies (direct and transitive) have been installed.
+      def dependencies_installed?(installed_specs)
+        dependencies.all? do |dep|
+          installed_specs.include?(dep.name) && dep.dependencies_installed?(installed_specs)
+        end
+      end
+
+      def to_s
+        "#<#{self.class} #{full_name} (#{state})>"
+      end
+    end
+
+    def self.call(*args, **kwargs)
+      new(*args, **kwargs).call
+    end
+
+    attr_reader :size
+
+    def initialize(installer, all_specs, size, standalone, force, local: false, skip: nil)
+      @installer = installer
+      @size = size
+      @standalone = standalone
+      @force = force
+      @local = local
+      @specs = all_specs.map {|s| SpecInstallation.new(s) }
+      specs_by_name = @specs.to_h {|s| [s.name, s] }
+      @specs.each do |spec_install|
+        spec_install.dependencies = spec_install.spec.dependencies.filter_map do |dep|
+          specs_by_name[dep.name] unless dep.type == :development || dep.name == spec_install.name
+        end
+      end
+      @specs.each do |spec_install|
+        spec_install.state = :installed if skip.include?(spec_install.name)
+      end if skip
+      @spec_set = all_specs
+      @rake = @specs.find {|s| s.name == "rake" unless s.installed? }
+    end
+
+    def call
+      if @rake
+        do_download(@rake, 0)
+        do_install(@rake, 0)
+        Gem::Specification.reset
+      end
+
+      if @size > 1
+        install_with_worker
+      else
+        install_serially
+      end
+
+      handle_error if failed_specs.any?
+      @specs
+    ensure
+      worker_pool&.stop
+    end
+
+    private
+
+    def failed_specs
+      @specs.select(&:failed?)
+    end
+
+    def install_with_worker
+      installed_specs = {}
+      enqueue_specs(installed_specs)
+
+      process_specs(installed_specs) until finished_installing?
+    end
+
+    def install_serially
+      until finished_installing?
+        raise "failed to find a spec to enqueue while installing serially" unless spec_install = @specs.find(&:ready_to_enqueue?)
+        spec_install.state = :enqueued
+        do_download(spec_install, 0)
+        do_install(spec_install, 0)
+      end
+    end
+
+    def worker_pool
+      @worker_pool ||= Bundler::Worker.new @size, "Parallel Installer", lambda {|spec_install, worker_num|
+        case spec_install.state
+        when :enqueued
+          do_download(spec_install, worker_num)
+        when :installable
+          do_install(spec_install, worker_num)
+        else
+          spec_install
+        end
+      }
+    end
+
+    def do_download(spec_install, worker_num)
+      Plugin.hook(Plugin::Events::GEM_BEFORE_INSTALL, spec_install)
+
+      gem_installer = Bundler::GemInstaller.new(
+        spec_install.spec, @installer, @standalone, worker_num, @force, @local
+      )
+
+      success, message = gem_installer.download
+
+      if success
+        spec_install.state = :downloaded
+      else
+        spec_install.error = "#{message}\n\n#{require_tree_for_spec(spec_install.spec)}"
+        spec_install.state = :failed
+      end
+
+      spec_install
+    end
+
+    def do_install(spec_install, worker_num)
+      gem_installer = Bundler::GemInstaller.new(
+        spec_install.spec, @installer, @standalone, worker_num, @force, @local
+      )
+      success, message = gem_installer.install_from_spec
+      if success
+        spec_install.state = :installed
+        spec_install.post_install_message = message unless message.nil?
+      else
+        spec_install.error = "#{message}\n\n#{require_tree_for_spec(spec_install.spec)}"
+        spec_install.state = :failed
+      end
+      Plugin.hook(Plugin::Events::GEM_AFTER_INSTALL, spec_install)
+      spec_install
+    end
+
+    # Dequeue a spec and save its post-install message and then enqueue the
+    # remaining specs.
+    # Some specs might've had to wait til this spec was installed to be
+    # processed so the call to `enqueue_specs` is important after every
+    # dequeue.
+    def process_specs(installed_specs)
+      spec = worker_pool.deq
+
+      if spec.installed?
+        installed_specs[spec.name] = true
+        return
+      elsif spec.failed?
+        return
+      elsif spec.ready_to_install?(installed_specs)
+        spec.state = :installable
+      end
+
+      worker_pool.enq(spec, priority: spec.enqueue_with_priority?)
+    end
+
+    def finished_installing?
+      @specs.all? do |spec|
+        return true if spec.failed?
+        spec.installed?
+      end
+    end
+
+    def handle_error
+      errors = failed_specs.map(&:error)
+      if exception = errors.find {|e| e.is_a?(Bundler::BundlerError) }
+        raise exception
+      end
+      raise Bundler::InstallError, errors.join("\n\n")
+    end
+
+    def require_tree_for_spec(spec)
+      tree = @spec_set.what_required(spec)
+      t = String.new("In #{File.basename(SharedHelpers.default_gemfile)}:\n")
+      tree.each_with_index do |s, depth|
+        t << "  " * depth.succ << s.name
+        unless tree.last == s
+          t << %( was resolved to #{s.version}, which depends on)
+        end
+        t << %(\n)
+      end
+      t
+    end
+
+    # Keys in the remains hash represent uninstalled gems specs.
+    # We enqueue all gem specs that do not have any dependencies.
+    # Later we call this lambda again to install specs that depended on
+    # previously installed specifications. We continue until all specs
+    # are installed.
+    def enqueue_specs(installed_specs)
+      @specs.each do |spec|
+        if spec.installed?
+          installed_specs[spec.name] = true
+          next
+        end
+
+        spec.state = :enqueued
+        worker_pool.enq spec
+      end
+    end
+  end
+end
diff --git a/lib/bundler/installer/standalone.rb b/lib/bundler/installer/standalone.rb
new file mode 100644
index 0000000000..8b4de64df5
--- /dev/null
+++ b/lib/bundler/installer/standalone.rb
@@ -0,0 +1,113 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Standalone
+    def initialize(groups, definition)
+      @specs = definition.specs_for(groups)
+    end
+
+    def generate
+      SharedHelpers.filesystem_access(bundler_path) do |p|
+        FileUtils.mkdir_p(p)
+      end
+      File.open File.join(bundler_path, "setup.rb"), "w" do |file|
+        file.puts "require 'rbconfig'"
+        file.puts prevent_gem_activation
+        file.puts define_path_helpers
+        file.puts reverse_rubygems_kernel_mixin
+        paths.each do |path|
+          if Pathname.new(path).absolute?
+            file.puts %($:.unshift "#{path}")
+          else
+            file.puts %($:.unshift File.expand_path("\#{__dir__}/#{path}"))
+          end
+        end
+      end
+    end
+
+    private
+
+    def paths
+      @specs.flat_map do |spec|
+        next if spec.name == "bundler"
+        Array(spec.require_paths).map do |path|
+          gem_path(path, spec).
+            sub(version_dir, '#{RUBY_ENGINE}/#{Gem.ruby_api_version}').
+            sub(extensions_dir, 'extensions/\k<platform>/#{Gem.extension_api_version}')
+          # This is a static string intentionally. It's interpolated at a later time.
+        end
+      end.compact
+    end
+
+    def version_dir
+      "#{RUBY_ENGINE}/#{Gem.ruby_api_version}"
+    end
+
+    def extensions_dir
+      %r{extensions/(?<platform>[^/]+)/#{Regexp.escape(Gem.extension_api_version)}}
+    end
+
+    def bundler_path
+      Bundler.root.join(Bundler.settings[:path].to_s, "bundler")
+    end
+
+    def gem_path(path, spec)
+      full_path = Pathname.new(path).absolute? ? path : File.join(spec.full_gem_path, path)
+      if spec.source.instance_of?(Source::Path) && spec.source.path.absolute?
+        full_path
+      else
+        SharedHelpers.relative_path_to(full_path, from: Bundler.root.join(bundler_path))
+      end
+    end
+
+    def prevent_gem_activation
+      <<~'END'
+        module Kernel
+          remove_method(:gem) if private_method_defined?(:gem)
+
+          def gem(*)
+          end
+
+          private :gem
+        end
+      END
+    end
+
+    def define_path_helpers
+      <<~'END'
+        unless defined?(Gem)
+          module Gem
+            def self.ruby_api_version
+              RbConfig::CONFIG["ruby_version"]
+            end
+
+            def self.extension_api_version
+              if 'no' == RbConfig::CONFIG['ENABLE_SHARED']
+                "#{ruby_api_version}-static"
+              else
+                ruby_api_version
+              end
+            end
+          end
+        end
+      END
+    end
+
+    def reverse_rubygems_kernel_mixin
+      <<~END
+      if Gem.respond_to?(:discover_gems_on_require=)
+        Gem.discover_gems_on_require = false
+      else
+        [::Kernel.singleton_class, ::Kernel].each do |k|
+          if k.private_method_defined?(:gem_original_require)
+            private_require = k.private_method_defined?(:require)
+            k.send(:remove_method, :require)
+            k.send(:define_method, :require, k.instance_method(:gem_original_require))
+            k.send(:private, :require) if private_require
+          end
+        end
+      end
+      END
+    end
+  end
+end
diff --git a/lib/bundler/lazy_specification.rb b/lib/bundler/lazy_specification.rb
new file mode 100644
index 0000000000..0da621d21f
--- /dev/null
+++ b/lib/bundler/lazy_specification.rb
@@ -0,0 +1,272 @@
+# frozen_string_literal: true
+
+require_relative "force_platform"
+
+module Bundler
+  class LazySpecification
+    include MatchMetadata
+    include MatchPlatform
+    include ForcePlatform
+
+    attr_reader :name, :version, :platform, :materialization
+    attr_accessor :source, :remote, :force_ruby_platform, :dependencies, :required_ruby_version, :required_rubygems_version, :overrides
+
+    #
+    # For backwards compatibility with existing lockfiles, if the most specific
+    # locked platform is not a specific platform like x86_64-linux or
+    # universal-java-11, then we keep the previous behaviour of resolving the
+    # best platform variant at materiliazation time. For previous bundler
+    # versions (before 2.2.0) this was always the case (except when the lockfile
+    # only included non-ruby platforms), but we're also keeping this behaviour
+    # on newer bundlers unless users generate the lockfile from scratch or
+    # explicitly add a more specific platform.
+    #
+    attr_accessor :most_specific_locked_platform
+
+    alias_method :runtime_dependencies, :dependencies
+
+    def self.from_spec(s)
+      lazy_spec = new(s.name, s.version, s.platform, s.source)
+      lazy_spec.dependencies = s.runtime_dependencies
+      lazy_spec.required_ruby_version = s.required_ruby_version
+      lazy_spec.required_rubygems_version = s.required_rubygems_version
+      lazy_spec.overrides = s.overrides if s.is_a?(LazySpecification)
+      lazy_spec
+    end
+
+    def initialize(name, version, platform, source = nil, **materialization_options)
+      @name          = name
+      @version       = version
+      @dependencies  = []
+      @required_ruby_version = Gem::Requirement.default
+      @required_rubygems_version = Gem::Requirement.default
+      @platform = platform || Gem::Platform::RUBY
+
+      @original_source = source
+      @source = source
+      @materialization_options = materialization_options
+
+      @force_ruby_platform = default_force_ruby_platform
+      @most_specific_locked_platform = nil
+      @materialization = nil
+    end
+
+    def missing?
+      @materialization == self
+    end
+
+    def incomplete?
+      @materialization.nil?
+    end
+
+    def source_changed?
+      @original_source != source
+    end
+
+    def full_name
+      @full_name ||= if platform == Gem::Platform::RUBY
+        "#{@name}-#{@version}"
+      else
+        "#{@name}-#{@version}-#{platform}"
+      end
+    end
+
+    def lock_name
+      @lock_name ||= name_tuple.lock_name
+    end
+
+    def name_tuple
+      Gem::NameTuple.new(@name, @version, @platform)
+    end
+
+    def ==(other)
+      full_name == other.full_name
+    end
+
+    def eql?(other)
+      full_name.eql?(other.full_name)
+    end
+
+    def hash
+      full_name.hash
+    end
+
+    ##
+    # Does this locked specification satisfy +dependency+?
+    #
+    # NOTE: Rubygems default requirement is ">= 0", which doesn't match
+    # prereleases of 0 versions, like "0.0.0.dev" or "0.0.0.SNAPSHOT". However,
+    # bundler users expect those to work. We need to make sure that Gemfile
+    # dependencies without explicit requirements (which use ">= 0" under the
+    # hood by default) are still valid for locked specs using this kind of
+    # versions. The method implements an ad-hoc fix for that. A better solution
+    # might be to change default rubygems requirement of dependencies to be ">=
+    # 0.A" but that's a major refactoring likely to break things. Hopefully we
+    # can attempt it in the future.
+    #
+
+    def satisfies?(dependency)
+      effective_requirement = dependency.requirement == Gem::Requirement.default ? Gem::Requirement.new(">= 0.A") : dependency.requirement
+
+      @name == dependency.name && effective_requirement.satisfied_by?(Gem::Version.new(@version))
+    end
+
+    def to_lock
+      out = String.new
+      out << "    #{lock_name}\n"
+
+      dependencies.sort_by(&:to_s).uniq.each do |dep|
+        next if dep.type == :development
+        out << "    #{dep.to_lock}\n"
+      end
+
+      out
+    end
+
+    def materialize_for_cache
+      source.remote!
+
+      materialize(self, &:first)
+    end
+
+    def materialized_for_installation
+      @materialization = materialize_for_installation
+
+      self unless incomplete?
+    end
+
+    def materialize_for_installation
+      source.local!
+
+      if use_exact_resolved_specifications?
+        spec = materialize(self) {|specs| choose_compatible(specs, fallback_to_non_installable: false) }
+        return spec if spec
+
+        # Exact spec is incompatible; in frozen mode, try to find a compatible platform variant
+        # In non-frozen mode, return nil to trigger re-resolution and lockfile update
+        if Bundler.frozen_bundle?
+          materialize([name, version]) {|specs| resolve_best_platform(specs) }
+        end
+      else
+        materialize([name, version]) {|specs| resolve_best_platform(specs) }
+      end
+    end
+
+    def inspect
+      "#<#{self.class} @name=\"#{name}\" (#{full_name.delete_prefix("#{name}-")})>"
+    end
+
+    def to_s
+      lock_name
+    end
+
+    def git_version
+      return unless source.is_a?(Bundler::Source::Git)
+      " #{source.revision[0..6]}"
+    end
+
+    def force_ruby_platform!
+      @force_ruby_platform = true
+    end
+
+    def replace_source_with!(gemfile_source)
+      return unless gemfile_source.can_lock?(self)
+
+      @source = gemfile_source
+
+      true
+    end
+
+    private
+
+    def use_exact_resolved_specifications?
+      !source.is_a?(Source::Path) && ruby_platform_materializes_to_ruby_platform?
+    end
+
+    # Try platforms in order of preference until finding a compatible spec.
+    # Used for legacy lockfiles and as a fallback when the exact locked spec
+    # is incompatible. Falls back to frozen bundle behavior if none match.
+    def resolve_best_platform(specs)
+      find_compatible_platform_spec(specs) || frozen_bundle_fallback(specs)
+    end
+
+    def find_compatible_platform_spec(specs)
+      candidate_platforms.each do |plat|
+        candidates = MatchPlatform.select_best_platform_match(specs, plat)
+        spec = choose_compatible(candidates, fallback_to_non_installable: false)
+        return spec if spec
+      end
+      nil
+    end
+
+    # Platforms to try in order of preference. Ruby platform is last since it
+    # requires compilation, but works when precompiled gems are incompatible.
+    def candidate_platforms
+      target = source.is_a?(Source::Path) ? platform : Bundler.local_platform
+      [target, platform, Gem::Platform::RUBY].uniq
+    end
+
+    # In frozen mode, accept any candidate. Will error at install time.
+    # When target differs from locked platform, prefer locked platform's candidates
+    # to preserve lockfile integrity.
+    def frozen_bundle_fallback(specs)
+      target = source.is_a?(Source::Path) ? platform : Bundler.local_platform
+      fallback_platform = target == platform ? target : platform
+      candidates = MatchPlatform.select_best_platform_match(specs, fallback_platform)
+      choose_compatible(candidates)
+    end
+
+    def ruby_platform_materializes_to_ruby_platform?
+      generic_platform = Bundler.generic_local_platform == Gem::Platform::JAVA ? Gem::Platform::JAVA : Gem::Platform::RUBY
+
+      (most_specific_locked_platform != generic_platform) || force_ruby_platform || Bundler.settings[:force_ruby_platform]
+    end
+
+    def materialize(query)
+      matching_specs = source.specs.search(query)
+      return self if matching_specs.empty?
+
+      yield matching_specs
+    end
+
+    # If in frozen mode, we fallback to a non-installable candidate because by
+    # doing this we avoid re-resolving and potentially end up changing the
+    # lockfile, which is not allowed. In that case, we will give a proper error
+    # about the mismatch higher up the stack, right before trying to install the
+    # bad gem.
+    def choose_compatible(candidates, fallback_to_non_installable: Bundler.frozen_bundle?)
+      override_list = overrides || []
+      search = candidates.reverse.find do |spec|
+        spec.is_a?(StubSpecification) || spec.matches_current_metadata_with_overrides?(override_list)
+      end
+      if search.nil? && fallback_to_non_installable
+        search = candidates.last
+      end
+
+      if search
+        validate_dependencies(search) if search.platform == platform
+
+        search.locked_platform = platform if search.instance_of?(RemoteSpecification) || search.instance_of?(EndpointSpecification)
+      end
+      search
+    end
+
+    # Validate dependencies of this locked spec are consistent with dependencies
+    # of the actual spec that was materialized.
+    #
+    # Note that unless we are in strict mode (which we set during installation)
+    # we don't validate dependencies of locally installed gems but
+    # accept what's in the lockfile instead for performance, since loading
+    # dependencies of locally installed gems would mean evaluating all gemspecs,
+    # which would affect `bundler/setup` performance.
+    def validate_dependencies(spec)
+      if !@materialization_options[:strict] && spec.is_a?(StubSpecification)
+        spec.dependencies = dependencies
+      else
+        if !source.is_a?(Source::Path) && spec.runtime_dependencies.sort != dependencies.sort
+          raise IncorrectLockfileDependencies.new(self, spec.runtime_dependencies, dependencies)
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/lockfile_generator.rb b/lib/bundler/lockfile_generator.rb
new file mode 100644
index 0000000000..2a3ad22480
--- /dev/null
+++ b/lib/bundler/lockfile_generator.rb
@@ -0,0 +1,119 @@
+# frozen_string_literal: true
+
+module Bundler
+  class LockfileGenerator
+    attr_reader :definition
+    attr_reader :out
+
+    # @private
+    def initialize(definition)
+      @definition = definition
+      @out = String.new
+    end
+
+    def self.generate(definition)
+      new(definition).generate!
+    end
+
+    def generate!
+      add_sources
+      add_platforms
+      add_dependencies
+      add_checksums
+      add_locked_ruby_version
+      add_bundled_with
+
+      out
+    end
+
+    private
+
+    def add_sources
+      definition.sources.lock_sources.each_with_index do |source, idx|
+        out << "\n" unless idx.zero?
+
+        # Add the source header
+        out << source.to_lock
+
+        # Find all specs for this source
+        specs = definition.resolve.select {|s| source.can_lock?(s) }
+        add_specs(specs)
+      end
+    end
+
+    def add_specs(specs)
+      # This needs to be sorted by full name so that
+      # gems with the same name, but different platform
+      # are ordered consistently
+      specs.sort_by(&:full_name).each do |spec|
+        next if spec.name == "bundler"
+        out << spec.to_lock
+      end
+    end
+
+    def add_platforms
+      add_section("PLATFORMS", definition.platforms)
+    end
+
+    def add_dependencies
+      out << "\nDEPENDENCIES\n"
+
+      handled = []
+      definition.dependencies.sort_by(&:to_s).each do |dep|
+        next if handled.include?(dep.name)
+        out << dep.to_lock << "\n"
+        handled << dep.name
+      end
+    end
+
+    def add_checksums
+      return unless definition.locked_checksums
+      checksums = definition.resolve.map do |spec|
+        spec.source.checksum_store.to_lock(spec)
+      end
+
+      add_section("CHECKSUMS", checksums + bundler_checksum)
+    end
+
+    def add_locked_ruby_version
+      return unless locked_ruby_version = definition.locked_ruby_version
+      add_section("RUBY VERSION", locked_ruby_version.to_s)
+    end
+
+    def add_bundled_with
+      add_section("BUNDLED WITH", definition.bundler_version_to_lock.to_s)
+    end
+
+    def add_section(name, value)
+      out << "\n#{name}\n"
+      case value
+      when Array
+        value.map(&:to_s).sort.each do |val|
+          out << "  #{val}\n"
+        end
+      when Hash
+        value.to_a.sort_by {|k, _| k.to_s }.each do |key, val|
+          out << "  #{key}: #{val}\n"
+        end
+      when String
+        out << "  #{value}\n"
+      else
+        raise ArgumentError, "#{value.inspect} can't be serialized in a lockfile"
+      end
+    end
+
+    def bundler_checksum
+      return [] if Bundler.gem_version.to_s.end_with?(".dev") || ENV["SKIP_BUNDLER_CHECKSUM"]
+
+      bundler_spec = definition.sources.metadata_source.specs.search(["bundler", Bundler.gem_version]).last
+      return [] unless File.exist?(bundler_spec.cache_file)
+
+      require "rubygems/package"
+
+      package = Gem::Package.new(bundler_spec.cache_file)
+      definition.sources.metadata_source.checksum_store.register(bundler_spec, Checksum.from_gem_package(package))
+
+      [definition.sources.metadata_source.checksum_store.to_lock(bundler_spec)]
+    end
+  end
+end
diff --git a/lib/bundler/lockfile_parser.rb b/lib/bundler/lockfile_parser.rb
new file mode 100644
index 0000000000..852fc631f3
--- /dev/null
+++ b/lib/bundler/lockfile_parser.rb
@@ -0,0 +1,328 @@
+# frozen_string_literal: true
+
+require_relative "shared_helpers"
+
+module Bundler
+  class LockfileParser
+    class Position
+      attr_reader :line, :column
+      def initialize(line, column)
+        @line = line
+        @column = column
+      end
+
+      def advance!(string)
+        lines = string.count("\n")
+        if lines > 0
+          @line += lines
+          @column = string.length - string.rindex("\n")
+        else
+          @column += string.length
+        end
+      end
+
+      def to_s
+        "#{line}:#{column}"
+      end
+    end
+
+    attr_reader(
+      :sources,
+      :metadata_source,
+      :dependencies,
+      :specs,
+      :platforms,
+      :most_specific_locked_platform,
+      :bundler_version,
+      :ruby_version,
+      :checksums,
+    )
+
+    BUNDLED      = "BUNDLED WITH"
+    DEPENDENCIES = "DEPENDENCIES"
+    CHECKSUMS    = "CHECKSUMS"
+    PLATFORMS    = "PLATFORMS"
+    RUBY         = "RUBY VERSION"
+    GIT          = "GIT"
+    GEM          = "GEM"
+    PATH         = "PATH"
+    PLUGIN       = "PLUGIN SOURCE"
+    SPECS        = "  specs:"
+    OPTIONS      = /^  ([a-z]+): (.*)$/i
+    SOURCE       = [GIT, GEM, PATH, PLUGIN].freeze
+
+    SECTIONS_BY_VERSION_INTRODUCED = {
+      Gem::Version.create("1.0") => [DEPENDENCIES, PLATFORMS, GIT, GEM, PATH].freeze,
+      Gem::Version.create("1.10") => [BUNDLED].freeze,
+      Gem::Version.create("1.12") => [RUBY].freeze,
+      Gem::Version.create("1.13") => [PLUGIN].freeze,
+      Gem::Version.create("2.5.0") => [CHECKSUMS].freeze,
+    }.freeze
+
+    KNOWN_SECTIONS = SECTIONS_BY_VERSION_INTRODUCED.values.flatten!.freeze
+
+    ENVIRONMENT_VERSION_SECTIONS = [BUNDLED, RUBY].freeze
+    deprecate_constant(:ENVIRONMENT_VERSION_SECTIONS)
+
+    def self.sections_in_lockfile(lockfile_contents)
+      sections = lockfile_contents.scan(/^\w[\w ]*$/)
+      sections.uniq!
+      sections
+    end
+
+    def self.unknown_sections_in_lockfile(lockfile_contents)
+      sections_in_lockfile(lockfile_contents) - KNOWN_SECTIONS
+    end
+
+    def self.sections_to_ignore(base_version = nil)
+      base_version &&= base_version.release
+      base_version ||= Gem::Version.create("1.0")
+      attributes = []
+      SECTIONS_BY_VERSION_INTRODUCED.each do |version, introduced|
+        next if version <= base_version
+        attributes += introduced
+      end
+      attributes
+    end
+
+    def self.bundled_with
+      lockfile = Bundler.default_lockfile
+      return unless lockfile.file?
+
+      lockfile_contents = Bundler.read_file(lockfile)
+      return unless lockfile_contents.include?(BUNDLED)
+
+      lockfile_contents.split(BUNDLED).last.strip
+    end
+
+    def initialize(lockfile, strict: false, lockfile_path: nil)
+      @platforms    = []
+      @sources      = []
+      @metadata_source = Source::Metadata.new
+      @dependencies = {}
+      @parse_method = nil
+      @specs        = {}
+      @lockfile_path = lockfile_path || begin
+        SharedHelpers.relative_lockfile_path
+      rescue GemfileNotFound
+        "Gemfile.lock"
+      end
+      @pos = Position.new(1, 1)
+      @strict = strict
+
+      if lockfile.match?(/<<<<<<<|=======|>>>>>>>|\|\|\|\|\|\|\|/)
+        raise LockfileError, "Your #{@lockfile_path} contains merge conflicts.\n" \
+          "Run `git checkout HEAD -- #{@lockfile_path}` first to get a clean lock."
+      end
+
+      @valid = lockfile.strip.empty? ||
+               lockfile.split(/(?:\r?\n)+/).any? {|l| KNOWN_SECTIONS.include?(l) }
+
+      unless @valid
+        SharedHelpers.feature_deprecated!(
+          "Your #{@lockfile_path} does not appear to be a valid lockfile. " \
+          "Run `rm #{@lockfile_path}` and then `bundle install` to generate a new lockfile. " \
+          "This will raise a LockfileError in a future version of Bundler."
+        )
+      end
+
+      lockfile.split(/((?:\r?\n)+)/) do |line|
+        # split alternates between the line and the following whitespace
+        next @pos.advance!(line) if line.match?(/^\s*$/)
+
+        if SOURCE.include?(line)
+          @parse_method = :parse_source
+          parse_source(line)
+        elsif line == DEPENDENCIES
+          @parse_method = :parse_dependency
+        elsif line == CHECKSUMS
+          # This is a temporary solution to make this feature disabled by default
+          # for all gemfiles that don't already explicitly include the feature.
+          @checksums = true
+          @parse_method = :parse_checksum
+        elsif line == PLATFORMS
+          @parse_method = :parse_platform
+        elsif line == RUBY
+          @parse_method = :parse_ruby
+        elsif line == BUNDLED
+          @parse_method = :parse_bundled_with
+        elsif /^[^\s]/.match?(line)
+          @parse_method = nil
+        elsif @parse_method
+          send(@parse_method, line)
+        end
+        @pos.advance!(line)
+      end
+
+      if @platforms.include?(Gem::Platform::X64_MINGW_LEGACY)
+        SharedHelpers.feature_deprecated!("Found x64-mingw32 in lockfile, which is deprecated and will be removed in the future.")
+      end
+
+      @most_specific_locked_platform = @platforms.min_by do |bundle_platform|
+        Gem::Platform.platform_specificity_match(bundle_platform, Bundler.local_platform)
+      end
+      @specs = @specs.values.sort_by!(&:full_name).each do |spec|
+        spec.most_specific_locked_platform = @most_specific_locked_platform
+      end
+    rescue ArgumentError => e
+      Bundler.ui.debug(e)
+      raise LockfileError, "Your lockfile is unreadable. Run `rm #{@lockfile_path}` " \
+        "and then `bundle install` to generate a new lockfile. The error occurred while " \
+        "evaluating #{@lockfile_path}:#{@pos}"
+    end
+
+    def may_include_redundant_platform_specific_gems?
+      bundler_version.nil? || bundler_version < Gem::Version.new("1.16.2")
+    end
+
+    def valid?
+      @valid
+    end
+
+    private
+
+    TYPES = {
+      GIT => Bundler::Source::Git,
+      GEM => Bundler::Source::Rubygems,
+      PATH => Bundler::Source::Path,
+      PLUGIN => Bundler::Plugin,
+    }.freeze
+
+    def parse_source(line)
+      case line
+      when SPECS
+        return unless TYPES.key?(@type)
+        @current_source = TYPES[@type].from_lock(@opts)
+        @sources << @current_source
+      when OPTIONS
+        value = $2
+        value = true if value == "true"
+        value = false if value == "false"
+
+        key = $1
+
+        if @opts[key]
+          @opts[key] = Array(@opts[key])
+          @opts[key] << value
+        else
+          @opts[key] = value
+        end
+      when *SOURCE
+        @current_source = nil
+        @opts = {}
+        @type = line
+      else
+        parse_spec(line)
+      end
+    end
+
+    space = / /
+    NAME_VERSION = /
+      ^(#{space}{2}|#{space}{4}|#{space}{6})(?!#{space}) # Exactly 2, 4, or 6 spaces at the start of the line
+      (.*?)                                              # Name
+      (?:#{space}\(([^-]*)                               # Space, followed by version
+      (?:-(.*))?\))?                                     # Optional platform
+      (!)?                                               # Optional pinned marker
+      (?:#{space}([^ ]+))?                               # Optional checksum
+      $                                                  # Line end
+    /xo
+
+    def parse_dependency(line)
+      return unless line =~ NAME_VERSION
+      spaces = $1
+      return unless spaces.size == 2
+      name = -$2
+      version = $3
+      pinned = $5
+
+      version = version.split(",").each(&:strip!) if version
+
+      dep = Bundler::Dependency.new(name, version)
+
+      if pinned && dep.name != "bundler"
+        spec = @specs.find {|_, v| v.name == dep.name }
+        dep.source = spec.last.source if spec
+
+        # Path sources need to know what the default name / version
+        # to use in the case that there are no gemspecs present. A fake
+        # gemspec is created based on the version set on the dependency
+        # TODO: Use the version from the spec instead of from the dependency
+        if version && version.size == 1 && version.first =~ /^\s*= (.+)\s*$/ && dep.source.is_a?(Bundler::Source::Path)
+          dep.source.name    = name
+          dep.source.version = $1
+        end
+      end
+
+      @dependencies[dep.name] = dep
+    end
+
+    def parse_checksum(line)
+      return unless line =~ NAME_VERSION
+
+      spaces = $1
+      return unless spaces.size == 2
+      checksums = $6
+      name = $2
+      version = $3
+      platform = $4
+
+      version = Gem::Version.new(version)
+      platform = platform ? Gem::Platform.new(platform) : Gem::Platform::RUBY
+      full_name = Gem::NameTuple.new(name, version, platform).full_name
+      spec = @specs[full_name]
+
+      if name == "bundler"
+        spec ||= LazySpecification.new(name, version, platform, @metadata_source)
+      end
+      return unless spec
+
+      if checksums
+        checksums.split(",") do |lock_checksum|
+          column = line.index(lock_checksum) + 1
+          checksum = Checksum.from_lock(lock_checksum, "#{@lockfile_path}:#{@pos.line}:#{column}")
+          spec.source.checksum_store.register(spec, checksum)
+        end
+      else
+        spec.source.checksum_store.register(spec, nil)
+      end
+    end
+
+    def parse_spec(line)
+      return unless line =~ NAME_VERSION
+      spaces = $1
+      name = -$2
+      version = $3
+
+      if spaces.size == 4
+        # only load platform for non-dependency (spec) line
+        platform = $4
+
+        version = Gem::Version.new(version)
+        platform = platform ? Gem::Platform.new(platform) : Gem::Platform::RUBY
+        @current_spec = LazySpecification.new(name, version, platform, @current_source, strict: @strict)
+        @current_source.add_dependency_names(name)
+
+        @specs[@current_spec.full_name] = @current_spec
+      elsif spaces.size == 6
+        version = version.split(",").each(&:strip!) if version
+        dep = Gem::Dependency.new(name, version)
+        @current_spec.dependencies << dep
+      end
+    end
+
+    def parse_platform(line)
+      @platforms << Gem::Platform.new($1.strip) if line =~ /^  (.*)$/
+    end
+
+    def parse_bundled_with(line)
+      line.strip!
+      return unless Gem::Version.correct?(line)
+      @bundler_version = Gem::Version.create(line)
+    end
+
+    def parse_ruby(line)
+      line.strip!
+      @ruby_version = line
+    end
+  end
+end
diff --git a/lib/bundler/man/.document b/lib/bundler/man/.document
new file mode 100644
index 0000000000..fb66f13c33
--- /dev/null
+++ b/lib/bundler/man/.document
@@ -0,0 +1 @@
+# Ignore all files in this directory
diff --git a/lib/bundler/man/bundle-add.1 b/lib/bundler/man/bundle-add.1
new file mode 100644
index 0000000000..0956aa83f1
--- /dev/null
+++ b/lib/bundler/man/bundle-add.1
@@ -0,0 +1,82 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-ADD" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-add\fR \- Add gem to the Gemfile and run bundle install
+.SH "SYNOPSIS"
+\fBbundle add\fR \fIGEM_NAME\fR [\-\-group=GROUP] [\-\-version=VERSION] [\-\-source=SOURCE] [\-\-path=PATH] [\-\-git=GIT|\-\-github=GITHUB] [\-\-branch=BRANCH] [\-\-ref=REF] [\-\-cooldown=NUMBER] [\-\-quiet] [\-\-skip\-install] [\-\-strict|\-\-optimistic]
+.SH "DESCRIPTION"
+Adds the named gem to the [\fBGemfile(5)\fR][Gemfile(5)] and run \fBbundle install\fR\. \fBbundle install\fR can be avoided by using the flag \fB\-\-skip\-install\fR\.
+.SH "OPTIONS"
+.TP
+\fB\-\-version=VERSION\fR, \fB\-v=VERSION\fR
+Specify version requirements(s) for the added gem\.
+.TP
+\fB\-\-group=GROUP\fR, \fB\-g=GROUP\fR
+Specify the group(s) for the added gem\. Multiple groups should be separated by commas\.
+.TP
+\fB\-\-source=SOURCE\fR, \fB\-s=SOURCE\fR
+Specify the source for the added gem\.
+.TP
+\fB\-\-require=REQUIRE\fR, \fB\-r=REQUIRE\fR
+Adds require path to gem\. Provide false, or a path as a string\.
+.TP
+\fB\-\-path=PATH\fR
+Specify the file system path for the added gem\.
+.TP
+\fB\-\-git=GIT\fR
+Specify the git source for the added gem\.
+.TP
+\fB\-\-github=GITHUB\fR
+Specify the github source for the added gem\.
+.TP
+\fB\-\-branch=BRANCH\fR
+Specify the git branch for the added gem\.
+.TP
+\fB\-\-ref=REF\fR
+Specify the git ref for the added gem\.
+.TP
+\fB\-\-glob=GLOB\fR
+Specify the location of a dependency's \.gemspec, expanded within Ruby (single quotes recommended)\.
+.TP
+\fB\-\-quiet\fR
+Do not print progress information to the standard output\.
+.TP
+\fB\-\-skip\-install\fR
+Adds the gem to the Gemfile but does not install it\.
+.TP
+\fB\-\-optimistic\fR
+Ignored (now default behavior)
+.TP
+\fB\-\-pessimistic\fR
+Adds pessimistic declaration of version\.
+.TP
+\fB\-\-strict\fR
+Adds strict declaration of version\.
+.TP
+\fB\-\-cooldown=<number>\fR
+Only consider gem versions published at least \fInumber\fR days ago when resolving\. Pass \fB0\fR to disable cooldown for this run\. See \fBcooldown\fR in bundle\-config(1) for precedence rules\.
+.SH "EXAMPLES"
+.IP "1." 4
+You can add the \fBrails\fR gem to the Gemfile without any version restriction\. The source of the gem will be the global source\.
+.IP
+\fBbundle add rails\fR
+.IP "2." 4
+You can add the \fBrails\fR gem with version greater than 1\.1 (not including 1\.1) and less than 3\.0\.
+.IP
+\fBbundle add rails \-\-version "> 1\.1, < 3\.0"\fR
+.IP "3." 4
+You can use the \fBhttps://gems\.example\.com\fR custom source and assign the gem to a group\.
+.IP
+\fBbundle add rails \-\-version ">= 5\.0\.0" \-\-source "https://gems\.example\.com" \-\-group "development"\fR
+.IP "4." 4
+The following adds the \fBgem\fR entry to the Gemfile without installing the gem\. You can install gems later via \fBbundle install\fR\.
+.IP
+\fBbundle add rails \-\-skip\-install\fR
+.IP "5." 4
+You can assign the gem to more than one group\.
+.IP
+\fBbundle add rails \-\-group "development, test"\fR
+.IP "" 0
+.SH "SEE ALSO"
+Gemfile(5) \fIhttps://bundler\.io/man/gemfile\.5\.html\fR, bundle\-remove(1) \fIbundle\-remove\.1\.html\fR
diff --git a/lib/bundler/man/bundle-add.1.ronn b/lib/bundler/man/bundle-add.1.ronn
new file mode 100644
index 0000000000..8c65af0cc0
--- /dev/null
+++ b/lib/bundler/man/bundle-add.1.ronn
@@ -0,0 +1,95 @@
+bundle-add(1) -- Add gem to the Gemfile and run bundle install
+==============================================================
+
+## SYNOPSIS
+
+`bundle add` <GEM_NAME> [--group=GROUP] [--version=VERSION] [--source=SOURCE]
+           [--path=PATH] [--git=GIT|--github=GITHUB] [--branch=BRANCH] [--ref=REF]
+           [--cooldown=NUMBER] [--quiet] [--skip-install] [--strict|--optimistic]
+
+## DESCRIPTION
+
+Adds the named gem to the [`Gemfile(5)`][Gemfile(5)] and run `bundle install`.
+`bundle install` can be avoided by using the flag `--skip-install`.
+
+## OPTIONS
+
+* `--version=VERSION`, `-v=VERSION`:
+  Specify version requirements(s) for the added gem.
+
+* `--group=GROUP`, `-g=GROUP`:
+  Specify the group(s) for the added gem. Multiple groups should be separated by commas.
+
+* `--source=SOURCE`, `-s=SOURCE`:
+  Specify the source for the added gem.
+
+* `--require=REQUIRE`, `-r=REQUIRE`:
+  Adds require path to gem. Provide false, or a path as a string.
+
+* `--path=PATH`:
+  Specify the file system path for the added gem.
+
+* `--git=GIT`:
+  Specify the git source for the added gem.
+
+* `--github=GITHUB`:
+  Specify the github source for the added gem.
+
+* `--branch=BRANCH`:
+  Specify the git branch for the added gem.
+
+* `--ref=REF`:
+  Specify the git ref for the added gem.
+
+* `--glob=GLOB`:
+  Specify the location of a dependency's .gemspec, expanded within Ruby (single quotes recommended).
+
+* `--quiet`:
+  Do not print progress information to the standard output.
+
+* `--skip-install`:
+  Adds the gem to the Gemfile but does not install it.
+
+* `--optimistic`:
+  Ignored (now default behavior)
+
+* `--pessimistic`:
+  Adds pessimistic declaration of version.
+
+* `--strict`:
+  Adds strict declaration of version.
+
+* `--cooldown=<number>`:
+  Only consider gem versions published at least <number> days ago when
+  resolving. Pass `0` to disable cooldown for this run. See `cooldown`
+  in bundle-config(1) for precedence rules.
+
+## EXAMPLES
+
+1. You can add the `rails` gem to the Gemfile without any version restriction.
+   The source of the gem will be the global source.
+
+   `bundle add rails`
+
+2. You can add the `rails` gem with version greater than 1.1 (not including 1.1) and less than 3.0.
+
+   `bundle add rails --version "> 1.1, < 3.0"`
+
+3. You can use the `https://gems.example.com` custom source and assign the gem
+   to a group.
+
+   `bundle add rails --version ">= 5.0.0" --source "https://gems.example.com" --group "development"`
+
+4. The following adds the `gem` entry to the Gemfile without installing the
+   gem. You can install gems later via `bundle install`.
+
+   `bundle add rails --skip-install`
+
+5. You can assign the gem to more than one group.
+
+   `bundle add rails --group "development, test"`
+
+## SEE ALSO
+
+[Gemfile(5)](https://bundler.io/man/gemfile.5.html),
+[bundle-remove(1)](bundle-remove.1.html)
diff --git a/lib/bundler/man/bundle-binstubs.1 b/lib/bundler/man/bundle-binstubs.1
new file mode 100644
index 0000000000..246daeae53
--- /dev/null
+++ b/lib/bundler/man/bundle-binstubs.1
@@ -0,0 +1,30 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-BINSTUBS" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-binstubs\fR \- Install the binstubs of the listed gems
+.SH "SYNOPSIS"
+\fBbundle binstubs\fR \fIGEM_NAME\fR [\-\-force] [\-\-standalone] [\-\-all\-platforms]
+.SH "DESCRIPTION"
+Binstubs are scripts that wrap around executables\. Bundler creates a small Ruby file (a binstub) that loads Bundler, runs the command, and puts it into \fBbin/\fR\. Binstubs are a shortcut\-or alternative\- to always using \fBbundle exec\fR\. This gives you a file that can be run directly, and one that will always run the correct gem version used by the application\.
+.P
+For example, if you run \fBbundle binstubs rspec\-core\fR, Bundler will create the file \fBbin/rspec\fR\. That file will contain enough code to load Bundler, tell it to load the bundled gems, and then run rspec\.
+.P
+This command generates binstubs for executables in \fBGEM_NAME\fR\. Binstubs are put into \fBbin\fR, or the directory specified by \fBbin\fR setting if it has been configured\. Calling binstubs with [GEM [GEM]] will create binstubs for all given gems\.
+.SH "OPTIONS"
+.TP
+\fB\-\-force\fR
+Overwrite existing binstubs if they exist\.
+.TP
+\fB\-\-standalone\fR
+Makes binstubs that can work without depending on Rubygems or Bundler at runtime\.
+.TP
+\fB\-\-shebang=SHEBANG\fR
+Specify a different shebang executable name than the default (default 'ruby')
+.TP
+\fB\-\-all\fR
+Create binstubs for all gems in the bundle\.
+.TP
+\fB\-\-all\-platforms\fR
+Install binstubs for all platforms\.
+
diff --git a/lib/bundler/man/bundle-binstubs.1.ronn b/lib/bundler/man/bundle-binstubs.1.ronn
new file mode 100644
index 0000000000..cbe5983f4d
--- /dev/null
+++ b/lib/bundler/man/bundle-binstubs.1.ronn
@@ -0,0 +1,42 @@
+bundle-binstubs(1) -- Install the binstubs of the listed gems
+=============================================================
+
+## SYNOPSIS
+
+`bundle binstubs` <GEM_NAME> [--force] [--standalone] [--all-platforms]
+
+## DESCRIPTION
+
+Binstubs are scripts that wrap around executables. Bundler creates a
+small Ruby file (a binstub) that loads Bundler, runs the command,
+and puts it into `bin/`. Binstubs are a shortcut-or alternative-
+to always using `bundle exec`. This gives you a file that can be run
+directly, and one that will always run the correct gem version
+used by the application.
+
+For example, if you run `bundle binstubs rspec-core`, Bundler will create
+the file `bin/rspec`. That file will contain enough code to load Bundler,
+tell it to load the bundled gems, and then run rspec.
+
+This command generates binstubs for executables in `GEM_NAME`.
+Binstubs are put into `bin`, or the directory specified by `bin` setting if it
+has been configured. Calling binstubs with [GEM [GEM]] will create binstubs for
+all given gems.
+
+## OPTIONS
+
+* `--force`:
+  Overwrite existing binstubs if they exist.
+
+* `--standalone`:
+  Makes binstubs that can work without depending on Rubygems or Bundler at
+  runtime.
+
+* `--shebang=SHEBANG`:
+  Specify a different shebang executable name than the default (default 'ruby')
+
+* `--all`:
+  Create binstubs for all gems in the bundle.
+
+* `--all-platforms`:
+  Install binstubs for all platforms.
diff --git a/lib/bundler/man/bundle-cache.1 b/lib/bundler/man/bundle-cache.1
new file mode 100644
index 0000000000..38ea047961
--- /dev/null
+++ b/lib/bundler/man/bundle-cache.1
@@ -0,0 +1,56 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-CACHE" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-cache\fR \- Package your needed \fB\.gem\fR files into your application
+.SH "SYNOPSIS"
+\fBbundle cache\fR [\fIOPTIONS\fR]
+.P
+alias: \fBpackage\fR, \fBpack\fR
+.SH "DESCRIPTION"
+Copy all of the \fB\.gem\fR files needed to run the application into the \fBvendor/cache\fR directory\. In the future, when running \fBbundle install(1)\fR \fIbundle\-install\.1\.html\fR, use the gems in the cache in preference to the ones on \fBrubygems\.org\fR\.
+.SH "OPTIONS"
+.TP
+\fB\-\-all\-platforms\fR
+Include gems for all platforms present in the lockfile, not only the current one\.
+.TP
+\fB\-\-cache\-path=CACHE\-PATH\fR
+Specify a different cache path than the default (vendor/cache)\.
+.TP
+\fB\-\-gemfile=GEMFILE\fR
+Use the specified gemfile instead of Gemfile\.
+.TP
+\fB\-\-no\-install\fR
+Don't install the gems, only update the cache\.
+.TP
+\fB\-\-quiet\fR
+Only output warnings and errors\.
+.SH "GIT AND PATH GEMS"
+The \fBbundle cache\fR command can also package \fB:git\fR and \fB:path\fR dependencies besides \.gem files\. This can be disabled setting \fBcache_all\fR to false\.
+.SH "SUPPORT FOR MULTIPLE PLATFORMS"
+When using gems that have different packages for different platforms, Bundler supports caching of gems for other platforms where the Gemfile has been resolved (i\.e\. present in the lockfile) in \fBvendor/cache\fR\. This needs to be enabled via the \fB\-\-all\-platforms\fR option\. This setting will be remembered in your local bundler configuration\.
+.SH "REMOTE FETCHING"
+By default, if you run \fBbundle install(1)\fR \fIbundle\-install\.1\.html\fR after running bundle cache(1) \fIbundle\-cache\.1\.html\fR, bundler will still connect to \fBrubygems\.org\fR to check whether a platform\-specific gem exists for any of the gems in \fBvendor/cache\fR\.
+.P
+For instance, consider this Gemfile(5):
+.IP "" 4
+.nf
+source "https://rubygems\.org"
+
+gem "nokogiri"
+.fi
+.IP "" 0
+.P
+If you run \fBbundle cache\fR under C Ruby, bundler will retrieve the version of \fBnokogiri\fR for the \fB"ruby"\fR platform\. If you deploy to JRuby and run \fBbundle install\fR, bundler is forced to check to see whether a \fB"java"\fR platformed \fBnokogiri\fR exists\.
+.P
+Even though the \fBnokogiri\fR gem for the Ruby platform is \fItechnically\fR acceptable on JRuby, it has a C extension that does not run on JRuby\. As a result, bundler will, by default, still connect to \fBrubygems\.org\fR to check whether it has a version of one of your gems more specific to your platform\.
+.P
+This problem is also not limited to the \fB"java"\fR platform\. A similar (common) problem can happen when developing on Windows and deploying to Linux, or even when developing on OSX and deploying to Linux\.
+.P
+If you know for sure that the gems packaged in \fBvendor/cache\fR are appropriate for the platform you are on, you can run \fBbundle install \-\-local\fR to skip checking for more appropriate gems, and use the ones in \fBvendor/cache\fR\.
+.P
+One way to be sure that you have the right platformed versions of all your gems is to run \fBbundle cache\fR on an identical machine and check in the gems\. For instance, you can run \fBbundle cache\fR on an identical staging box during your staging process, and check in the \fBvendor/cache\fR before deploying to production\.
+.P
+By default, bundle cache(1) \fIbundle\-cache\.1\.html\fR fetches and also installs the gems to the default location\. To package the dependencies to \fBvendor/cache\fR without installing them to the local install location, you can run \fBbundle cache \-\-no\-install\fR\.
+.SH "HISTORY"
+In Bundler 2\.1, \fBcache\fR took in the functionalities of \fBpackage\fR and now \fBpackage\fR and \fBpack\fR are aliases of \fBcache\fR\.
diff --git a/lib/bundler/man/bundle-cache.1.ronn b/lib/bundler/man/bundle-cache.1.ronn
new file mode 100644
index 0000000000..51846c96b4
--- /dev/null
+++ b/lib/bundler/man/bundle-cache.1.ronn
@@ -0,0 +1,95 @@
+bundle-cache(1) -- Package your needed `.gem` files into your application
+=========================================================================
+
+## SYNOPSIS
+
+`bundle cache` [*OPTIONS*]
+
+alias: `package`, `pack`
+
+## DESCRIPTION
+
+Copy all of the `.gem` files needed to run the application into the
+`vendor/cache` directory. In the future, when running [`bundle install(1)`](bundle-install.1.html),
+use the gems in the cache in preference to the ones on `rubygems.org`.
+
+## OPTIONS
+
+* `--all-platforms`:
+  Include gems for all platforms present in the lockfile, not only the current one.
+
+* `--cache-path=CACHE-PATH`:
+  Specify a different cache path than the default (vendor/cache).
+
+* `--gemfile=GEMFILE`:
+  Use the specified gemfile instead of Gemfile.
+
+* `--no-install`:
+  Don't install the gems, only update the cache.
+
+* `--quiet`:
+  Only output warnings and errors.
+
+## GIT AND PATH GEMS
+
+The `bundle cache` command can also package `:git` and `:path` dependencies
+besides .gem files. This can be disabled setting `cache_all` to false.
+
+## SUPPORT FOR MULTIPLE PLATFORMS
+
+When using gems that have different packages for different platforms, Bundler
+supports caching of gems for other platforms where the Gemfile has been resolved
+(i.e. present in the lockfile) in `vendor/cache`.  This needs to be enabled via
+the `--all-platforms` option. This setting will be remembered in your local
+bundler configuration.
+
+## REMOTE FETCHING
+
+By default, if you run [`bundle install(1)`](bundle-install.1.html) after running
+[bundle cache(1)](bundle-cache.1.html), bundler will still connect to `rubygems.org`
+to check whether a platform-specific gem exists for any of the gems
+in `vendor/cache`.
+
+For instance, consider this Gemfile(5):
+
+    source "https://rubygems.org"
+
+    gem "nokogiri"
+
+If you run `bundle cache` under C Ruby, bundler will retrieve
+the version of `nokogiri` for the `"ruby"` platform. If you deploy
+to JRuby and run `bundle install`, bundler is forced to check to
+see whether a `"java"` platformed `nokogiri` exists.
+
+Even though the `nokogiri` gem for the Ruby platform is
+_technically_ acceptable on JRuby, it has a C extension
+that does not run on JRuby. As a result, bundler will, by default,
+still connect to `rubygems.org` to check whether it has a version
+of one of your gems more specific to your platform.
+
+This problem is also not limited to the `"java"` platform.
+A similar (common) problem can happen when developing on Windows
+and deploying to Linux, or even when developing on OSX and
+deploying to Linux.
+
+If you know for sure that the gems packaged in `vendor/cache`
+are appropriate for the platform you are on, you can run
+`bundle install --local` to skip checking for more appropriate
+gems, and use the ones in `vendor/cache`.
+
+One way to be sure that you have the right platformed versions
+of all your gems is to run `bundle cache` on an identical
+machine and check in the gems. For instance, you can run
+`bundle cache` on an identical staging box during your
+staging process, and check in the `vendor/cache` before
+deploying to production.
+
+By default, [bundle cache(1)](bundle-cache.1.html) fetches and also
+installs the gems to the default location. To package the
+dependencies to `vendor/cache` without installing them to the
+local install location, you can run `bundle cache --no-install`.
+
+## HISTORY
+
+In Bundler 2.1, `cache` took in the functionalities of `package` and now
+`package` and `pack` are aliases of `cache`.
diff --git a/lib/bundler/man/bundle-check.1 b/lib/bundler/man/bundle-check.1
new file mode 100644
index 0000000000..6cd474d90a
--- /dev/null
+++ b/lib/bundler/man/bundle-check.1
@@ -0,0 +1,21 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-CHECK" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-check\fR \- Verifies if dependencies are satisfied by installed gems
+.SH "SYNOPSIS"
+\fBbundle check\fR [\-\-dry\-run] [\-\-gemfile=FILE]
+.SH "DESCRIPTION"
+\fBcheck\fR searches the local machine for each of the gems requested in the Gemfile\. If all gems are found, Bundler prints a success message and exits with a status of 0\.
+.P
+If not, the first missing gem is listed and Bundler exits status 1\.
+.P
+If the lockfile needs to be updated then it will be resolved using the gems installed on the local machine, if they satisfy the requirements\.
+.SH "OPTIONS"
+.TP
+\fB\-\-dry\-run\fR
+Locks the [\fBGemfile(5)\fR][Gemfile(5)] before running the command\.
+.TP
+\fB\-\-gemfile=GEMFILE\fR
+Use the specified gemfile instead of the [\fBGemfile(5)\fR][Gemfile(5)]\.
+
diff --git a/lib/bundler/man/bundle-check.1.ronn b/lib/bundler/man/bundle-check.1.ronn
new file mode 100644
index 0000000000..92589159c9
--- /dev/null
+++ b/lib/bundler/man/bundle-check.1.ronn
@@ -0,0 +1,26 @@
+bundle-check(1) -- Verifies if dependencies are satisfied by installed gems
+===========================================================================
+
+## SYNOPSIS
+
+`bundle check` [--dry-run]
+               [--gemfile=FILE]
+
+## DESCRIPTION
+
+`check` searches the local machine for each of the gems requested in the
+Gemfile. If all gems are found, Bundler prints a success message and exits with
+a status of 0.
+
+If not, the first missing gem is listed and Bundler exits status 1.
+
+If the lockfile needs to be updated then it will be resolved using the gems
+installed on the local machine, if they satisfy the requirements.
+
+## OPTIONS
+
+* `--dry-run`:
+  Locks the [`Gemfile(5)`][Gemfile(5)] before running the command.
+
+* `--gemfile=GEMFILE`:
+  Use the specified gemfile instead of the [`Gemfile(5)`][Gemfile(5)].
diff --git a/lib/bundler/man/bundle-clean.1 b/lib/bundler/man/bundle-clean.1
new file mode 100644
index 0000000000..eb90636c17
--- /dev/null
+++ b/lib/bundler/man/bundle-clean.1
@@ -0,0 +1,17 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-CLEAN" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-clean\fR \- Cleans up unused gems in your bundler directory
+.SH "SYNOPSIS"
+\fBbundle clean\fR [\-\-dry\-run] [\-\-force]
+.SH "DESCRIPTION"
+This command will remove all unused gems in your bundler directory\. This is useful when you have made many changes to your gem dependencies\.
+.SH "OPTIONS"
+.TP
+\fB\-\-dry\-run\fR
+Print the changes, but do not clean the unused gems\.
+.TP
+\fB\-\-force\fR
+Forces cleaning up unused gems even if Bundler is configured to use globally installed gems\. As a consequence, removes all system gems except for the ones in the current application\.
+
diff --git a/lib/bundler/man/bundle-clean.1.ronn b/lib/bundler/man/bundle-clean.1.ronn
new file mode 100644
index 0000000000..dae27c21ee
--- /dev/null
+++ b/lib/bundler/man/bundle-clean.1.ronn
@@ -0,0 +1,18 @@
+bundle-clean(1) -- Cleans up unused gems in your bundler directory
+==================================================================
+
+## SYNOPSIS
+
+`bundle clean` [--dry-run] [--force]
+
+## DESCRIPTION
+
+This command will remove all unused gems in your bundler directory. This is
+useful when you have made many changes to your gem dependencies.
+
+## OPTIONS
+
+* `--dry-run`:
+  Print the changes, but do not clean the unused gems.
+* `--force`:
+  Forces cleaning up unused gems even if Bundler is configured to use globally installed gems. As a consequence, removes all system gems except for the ones in the current application.
diff --git a/lib/bundler/man/bundle-config.1 b/lib/bundler/man/bundle-config.1
new file mode 100644
index 0000000000..c055c8a415
--- /dev/null
+++ b/lib/bundler/man/bundle-config.1
@@ -0,0 +1,343 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-CONFIG" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-config\fR \- Set bundler configuration options
+.SH "SYNOPSIS"
+\fBbundle config\fR [list]
+.br
+\fBbundle config\fR [get [\-\-local|\-\-global]] NAME
+.br
+\fBbundle config\fR [set [\-\-local|\-\-global]] NAME VALUE
+.br
+\fBbundle config\fR unset [\-\-local|\-\-global] NAME
+.SH "DESCRIPTION"
+This command allows you to interact with Bundler's configuration system\.
+.P
+Bundler loads configuration settings in this order:
+.IP "1." 4
+Local config (\fB<project_root>/\.bundle/config\fR or \fB$BUNDLE_APP_CONFIG/config\fR)
+.IP "2." 4
+Environmental variables (\fBENV\fR)
+.IP "3." 4
+Global config (\fB~/\.bundle/config\fR)
+.IP "4." 4
+Bundler default config
+.IP "" 0
+.P
+Executing \fBbundle\fR with the \fBBUNDLE_IGNORE_CONFIG\fR environment variable set will cause it to ignore all configuration\.
+.SH "SUB\-COMMANDS"
+.SS "list (default command)"
+Executing \fBbundle config list\fR will print a list of all bundler configuration for the current bundle, and where that configuration was set\.
+.SS "get"
+Executing \fBbundle config get <name>\fR will print the value of that configuration setting, and all locations where it was set\.
+.P
+\fBOPTIONS\fR
+.TP
+\fB\-\-local\fR
+Get configuration from configuration file for the local application, namely, \fB<project_root>/\.bundle/config\fR, or \fB$BUNDLE_APP_CONFIG/config\fR if \fBBUNDLE_APP_CONFIG\fR is set\.
+.TP
+\fB\-\-global\fR
+Get configuration from configuration file global to all bundles executed as the current user, namely, from \fB~/\.bundle/config\fR\.
+.SS "set"
+Executing \fBbundle config set <name> <value>\fR defaults to setting \fBlocal\fR configuration if executing from within a local application, otherwise it will set \fBglobal\fR configuration\.
+.P
+\fBOPTIONS\fR
+.TP
+\fB\-\-local\fR
+Executing \fBbundle config set \-\-local <name> <value>\fR will set that configuration in the directory for the local application\. The configuration will be stored in \fB<project_root>/\.bundle/config\fR\. If \fBBUNDLE_APP_CONFIG\fR is set, the configuration will be stored in \fB$BUNDLE_APP_CONFIG/config\fR\.
+.TP
+\fB\-\-global\fR
+Executing \fBbundle config set \-\-global <name> <value>\fR will set that configuration to the value specified for all bundles executed as the current user\. The configuration will be stored in \fB~/\.bundle/config\fR\. If \fIname\fR already is set, \fIname\fR will be overridden and user will be warned\.
+.SS "unset"
+Executing \fBbundle config unset <name>\fR will delete the configuration in both local and global sources\.
+.P
+\fBOPTIONS\fR
+.TP
+\fB\-\-local\fR
+Executing \fBbundle config unset \-\-local <name>\fR will delete the configuration only from the local application\.
+.TP
+\fB\-\-global\fR
+Executing \fBbundle config unset \-\-global <name>\fR will delete the configuration only from the user configuration\.
+.SH "CONFIGURATION KEYS"
+Configuration keys in bundler have two forms: the canonical form and the environment variable form\.
+.P
+For instance, passing the \fB\-\-without\fR flag to bundle install(1) \fIbundle\-install\.1\.html\fR prevents Bundler from installing certain groups specified in the Gemfile(5)\. Bundler persists this value in \fBapp/\.bundle/config\fR so that calls to \fBBundler\.setup\fR do not try to find gems from the \fBGemfile\fR that you didn't install\. Additionally, subsequent calls to bundle install(1) \fIbundle\-install\.1\.html\fR remember this setting and skip those groups\.
+.P
+The canonical form of this configuration is \fB"without"\fR\. To convert the canonical form to the environment variable form, capitalize it, and prepend \fBBUNDLE_\fR\. The environment variable form of \fB"without"\fR is \fBBUNDLE_WITHOUT\fR\.
+.P
+Any periods in the configuration keys must be replaced with two underscores when setting it via environment variables\. The configuration key \fBlocal\.rack\fR becomes the environment variable \fBBUNDLE_LOCAL__RACK\fR\.
+.SH "LIST OF AVAILABLE KEYS"
+The following is a list of all configuration keys and their purpose\. You can learn more about their operation in bundle install(1) \fIbundle\-install\.1\.html\fR\.
+.IP "\(bu" 4
+\fBapi_request_size\fR (\fBBUNDLE_API_REQUEST_SIZE\fR): Configure how many dependencies to fetch when resolving the specifications\. This configuration is only used when fetching specifications from RubyGems servers that didn't implement the Compact Index API\. Defaults to 100\.
+.IP "\(bu" 4
+\fBauto_install\fR (\fBBUNDLE_AUTO_INSTALL\fR): Automatically run \fBbundle install\fR when gems are missing\.
+.IP "\(bu" 4
+\fBbin\fR (\fBBUNDLE_BIN\fR): If configured, \fBbundle binstubs\fR will install executables from gems in the bundle to the specified directory\. Otherwise it will create them in a \fBbin\fR directory relative to the Gemfile directory\. These executables run in Bundler's context\. If used, you might add this directory to your environment's \fBPATH\fR variable\. For instance, if the \fBrails\fR gem comes with a \fBrails\fR executable, \fBbundle binstubs\fR will create a \fBbin/rails\fR executable that ensures that all referred dependencies will be resolved using the bundled gems\.
+.IP "\(bu" 4
+\fBcache_all\fR (\fBBUNDLE_CACHE_ALL\fR): Cache all gems, including path and git gems\. This needs to be explicitly before bundler 4, but will be the default on bundler 4\.
+.IP "\(bu" 4
+\fBcache_all_platforms\fR (\fBBUNDLE_CACHE_ALL_PLATFORMS\fR): Cache gems for all platforms\.
+.IP "\(bu" 4
+\fBcache_path\fR (\fBBUNDLE_CACHE_PATH\fR): The directory that bundler will place cached gems in when running \fBbundle package\fR, and that bundler will look in when installing gems\. Defaults to \fBvendor/cache\fR\.
+.IP "\(bu" 4
+\fBclean\fR (\fBBUNDLE_CLEAN\fR): Whether Bundler should run \fBbundle clean\fR automatically after \fBbundle install\fR\. Defaults to \fBtrue\fR in Bundler 4, as long as \fBpath\fR is not explicitly configured\.
+.IP "\(bu" 4
+\fBconsole\fR (\fBBUNDLE_CONSOLE\fR): The console that \fBbundle console\fR starts\. Defaults to \fBirb\fR\.
+.IP "\(bu" 4
+\fBcooldown\fR (\fBBUNDLE_COOLDOWN\fR): Number of days a published gem version must age before bundler will resolve to it\. Defaults to unset (no cooldown)\. Pass \fB0\fR to disable cooldown for an individual run\.
+.IP
+The effective cooldown for any given gem is resolved from three layers, highest precedence first:
+.IP "1." 4
+CLI flag \fB\-\-cooldown N\fR on \fBinstall\fR, \fBupdate\fR, \fBadd\fR, and \fBoutdated\fR\.
+.IP "2." 4
+This setting (\fBbundle config set cooldown N\fR or \fBBUNDLE_COOLDOWN=N\fR)\.
+.IP "3." 4
+The per\-source \fBcooldown:\fR keyword in the Gemfile, such as \fBsource "https://rubygems\.org", cooldown: 7\fR\.
+.IP "" 0
+.IP
+The CLI flag and this setting apply uniformly to every source, including ones declared with their own \fBcooldown:\fR value\. To keep a private registry permanently exempt while still cooling down public gems, declare \fBsource "https://internal", cooldown: 0\fR in the Gemfile; remember that \fB\-\-cooldown N\fR on the command line will still override it for that single run\.
+.IP
+Cooldown filtering depends on the gem server providing a per\-version \fBcreated_at\fR timestamp in the v2 compact\-index format\. Versions without that metadata \- older gem servers, historical entries that predate the v2 cutover on \fBrubygems\.org\fR, or private registries that still emit the v1 format \- are treated as outside the cooldown window and remain resolvable\. If you rely on cooldown for supply\-chain protection, confirm that the gem server emits \fBcreated_at\fR in its \fB/info/<gem>\fR responses\.
+.IP "\(bu" 4
+\fBdefault_cli_command\fR (\fBBUNDLE_DEFAULT_CLI_COMMAND\fR): The command that running \fBbundle\fR without arguments should run\. Defaults to \fBcli_help\fR since Bundler 4, but can also be \fBinstall\fR which was the previous default\.
+.IP "\(bu" 4
+\fBdeployment\fR (\fBBUNDLE_DEPLOYMENT\fR): Equivalent to setting \fBfrozen\fR to \fBtrue\fR and \fBpath\fR to \fBvendor/bundle\fR\.
+.IP "\(bu" 4
+\fBdisable_checksum_validation\fR (\fBBUNDLE_DISABLE_CHECKSUM_VALIDATION\fR): Allow installing gems even if they do not match the checksum provided by RubyGems\.
+.IP "\(bu" 4
+\fBdisable_exec_load\fR (\fBBUNDLE_DISABLE_EXEC_LOAD\fR): Stop Bundler from using \fBload\fR to launch an executable in\-process in \fBbundle exec\fR\.
+.IP "\(bu" 4
+\fBdisable_local_branch_check\fR (\fBBUNDLE_DISABLE_LOCAL_BRANCH_CHECK\fR): Allow Bundler to use a local git override without a branch specified in the Gemfile\.
+.IP "\(bu" 4
+\fBdisable_local_revision_check\fR (\fBBUNDLE_DISABLE_LOCAL_REVISION_CHECK\fR): Allow Bundler to use a local git override without checking if the revision present in the lockfile is present in the repository\.
+.IP "\(bu" 4
+\fBdisable_shared_gems\fR (\fBBUNDLE_DISABLE_SHARED_GEMS\fR): Stop Bundler from accessing gems installed to RubyGems' normal location\.
+.IP "\(bu" 4
+\fBdisable_version_check\fR (\fBBUNDLE_DISABLE_VERSION_CHECK\fR): Stop Bundler from checking if a newer Bundler version is available on rubygems\.org\.
+.IP "\(bu" 4
+\fBforce_ruby_platform\fR (\fBBUNDLE_FORCE_RUBY_PLATFORM\fR): Ignore the current machine's platform and install only \fBruby\fR platform gems\. As a result, gems with native extensions will be compiled from source\.
+.IP "\(bu" 4
+\fBfrozen\fR (\fBBUNDLE_FROZEN\fR): Disallow any automatic changes to \fBGemfile\.lock\fR\. Bundler commands will be blocked unless the lockfile can be installed exactly as written\. Usually this will happen when changing the \fBGemfile\fR manually and forgetting to update the lockfile through \fBbundle lock\fR or \fBbundle install\fR\.
+.IP "\(bu" 4
+\fBgem\.github_username\fR (\fBBUNDLE_GEM__GITHUB_USERNAME\fR): Sets a GitHub username or organization to be used in the \fBREADME\fR and \fB\.gemspec\fR files when you create a new gem via \fBbundle gem\fR command\. It can be overridden by passing an explicit \fB\-\-github\-username\fR flag to \fBbundle gem\fR\.
+.IP "\(bu" 4
+\fBgem\.push_key\fR (\fBBUNDLE_GEM__PUSH_KEY\fR): Sets the \fB\-\-key\fR parameter for \fBgem push\fR when using the \fBrake release\fR command with a private gemstash server\.
+.IP "\(bu" 4
+\fBgemfile\fR (\fBBUNDLE_GEMFILE\fR): The name of the file that bundler should use as the \fBGemfile\fR\. This location of this file also sets the root of the project, which is used to resolve relative paths in the \fBGemfile\fR, among other things\. By default, bundler will search up from the current working directory until it finds a \fBGemfile\fR\.
+.IP "\(bu" 4
+\fBglobal_gem_cache\fR (\fBBUNDLE_GLOBAL_GEM_CACHE\fR): Whether Bundler should cache all gems and compiled extensions globally, rather than locally to the configured installation path\.
+.IP "\(bu" 4
+\fBignore_funding_requests\fR (\fBBUNDLE_IGNORE_FUNDING_REQUESTS\fR): When set, no funding requests will be printed\.
+.IP "\(bu" 4
+\fBignore_messages\fR (\fBBUNDLE_IGNORE_MESSAGES\fR): When set, no post install messages will be printed\. To silence a single gem, use dot notation like \fBignore_messages\.httparty true\fR\.
+.IP "\(bu" 4
+\fBinit_gems_rb\fR (\fBBUNDLE_INIT_GEMS_RB\fR): Generate a \fBgems\.rb\fR instead of a \fBGemfile\fR when running \fBbundle init\fR\.
+.IP "\(bu" 4
+\fBjobs\fR (\fBBUNDLE_JOBS\fR): The number of gems Bundler can download and install in parallel\. Defaults to the number of available processors\.
+.IP "\(bu" 4
+\fBlockfile\fR (\fBBUNDLE_LOCKFILE\fR): The path to the lockfile that bundler should use\. By default, Bundler adds \fB\.lock\fR to the end of the \fBgemfile\fR entry\. Can be set to \fBfalse\fR in the Gemfile to disable lockfile creation entirely (see gemfile(5))\.
+.IP "\(bu" 4
+\fBlockfile_checksums\fR (\fBBUNDLE_LOCKFILE_CHECKSUMS\fR): Whether Bundler should include a checksums section in new lockfiles, to protect from compromised gem sources\. Defaults to true\.
+.IP "\(bu" 4
+\fBno_build_extension\fR (\fBBUNDLE_NO_BUILD_EXTENSION\fR): Whether Bundler should skip building native extensions during installation\. When set, gems are installed without compiling their C extensions\. To build extensions later, unset this setting and run \fBbundle pristine <gem>\fR\.
+.IP "\(bu" 4
+\fBno_install\fR (\fBBUNDLE_NO_INSTALL\fR): Whether \fBbundle package\fR should skip installing gems\.
+.IP "\(bu" 4
+\fBno_install_plugin\fR (\fBBUNDLE_NO_INSTALL_PLUGIN\fR): Whether Bundler should skip installing RubyGems plugins during installation\. When set, plugin files are not written to the plugins directory\. To install plugins later, unset this setting and run \fBbundle pristine <gem>\fR\.
+.IP "\(bu" 4
+\fBno_prune\fR (\fBBUNDLE_NO_PRUNE\fR): Whether Bundler should leave outdated gems unpruned when caching\.
+.IP "\(bu" 4
+\fBonly\fR (\fBBUNDLE_ONLY\fR): A space\-separated list of groups to install only gems of the specified groups\. Please check carefully if you want to install also gems without a group, because they get put inside \fBdefault\fR group\. For example \fBonly test:default\fR will install all gems specified in test group and without one\.
+.IP "\(bu" 4
+\fBpath\fR (\fBBUNDLE_PATH\fR): The location on disk where all gems in your bundle will be located regardless of \fB$GEM_HOME\fR or \fB$GEM_PATH\fR values\. Bundle gems not found in this location will be installed by \fBbundle install\fR\. When not set, Bundler install by default to a \fB\.bundle\fR directory relative to repository root in Bundler 4, and to the default system path (\fBGem\.dir\fR) before Bundler 4\. That means that before Bundler 4, Bundler shares this location with Rubygems, and \fBgem install \|\.\|\.\|\.\fR will have gems installed in the same location and therefore, gems installed without \fBpath\fR set will show up by calling \fBgem list\fR\. This will not be the case in Bundler 4\.
+.IP "\(bu" 4
+\fBpath\.system\fR (\fBBUNDLE_PATH__SYSTEM\fR): Whether Bundler will install gems into the default system path (\fBGem\.dir\fR)\.
+.IP "\(bu" 4
+\fBplugins\fR (\fBBUNDLE_PLUGINS\fR): Enable Bundler's experimental plugin system\.
+.IP "\(bu" 4
+\fBprefer_patch\fR (\fBBUNDLE_PREFER_PATCH\fR): Prefer updating only to next patch version during updates\. Makes \fBbundle update\fR calls equivalent to \fBbundler update \-\-patch\fR\.
+.IP "\(bu" 4
+\fBredirect\fR (\fBBUNDLE_REDIRECT\fR): The number of redirects allowed for network requests\. Defaults to \fB5\fR\.
+.IP "\(bu" 4
+\fBretry\fR (\fBBUNDLE_RETRY\fR): The number of times to retry failed network requests\. Defaults to \fB3\fR\.
+.IP "\(bu" 4
+\fBshebang\fR (\fBBUNDLE_SHEBANG\fR): The program name that should be invoked for generated binstubs\. Defaults to the ruby install name used to generate the binstub\.
+.IP "\(bu" 4
+\fBsilence_deprecations\fR (\fBBUNDLE_SILENCE_DEPRECATIONS\fR): Whether Bundler should silence deprecation warnings for behavior that will be changed in the next major version\.
+.IP "\(bu" 4
+\fBsilence_root_warning\fR (\fBBUNDLE_SILENCE_ROOT_WARNING\fR): Silence the warning Bundler prints when installing gems as root\.
+.IP "\(bu" 4
+\fBsimulate_version\fR (\fBBUNDLE_SIMULATE_VERSION\fR): The virtual version Bundler should use for activating feature flags\. Can be used to simulate all the new functionality that will be enabled in a future major version\.
+.IP "\(bu" 4
+\fBssl_ca_cert\fR (\fBBUNDLE_SSL_CA_CERT\fR): Path to a designated CA certificate file or folder containing multiple certificates for trusted CAs in PEM format\.
+.IP "\(bu" 4
+\fBssl_client_cert\fR (\fBBUNDLE_SSL_CLIENT_CERT\fR): Path to a designated file containing a X\.509 client certificate and key in PEM format\.
+.IP "\(bu" 4
+\fBssl_verify_mode\fR (\fBBUNDLE_SSL_VERIFY_MODE\fR): The SSL verification mode Bundler uses when making HTTPS requests\. Defaults to verify peer\.
+.IP "\(bu" 4
+\fBsystem_bindir\fR (\fBBUNDLE_SYSTEM_BINDIR\fR): The location where RubyGems installs binstubs\. Defaults to \fBGem\.bindir\fR\.
+.IP "\(bu" 4
+\fBtimeout\fR (\fBBUNDLE_TIMEOUT\fR): The seconds allowed before timing out for network requests\. Defaults to \fB10\fR\.
+.IP "\(bu" 4
+\fBupdate_requires_all_flag\fR (\fBBUNDLE_UPDATE_REQUIRES_ALL_FLAG\fR): Require passing \fB\-\-all\fR to \fBbundle update\fR when everything should be updated, and disallow passing no options to \fBbundle update\fR\.
+.IP "\(bu" 4
+\fBuser_agent\fR (\fBBUNDLE_USER_AGENT\fR): The custom user agent fragment Bundler includes in API requests\.
+.IP "\(bu" 4
+\fBverbose\fR (\fBBUNDLE_VERBOSE\fR): Whether Bundler should print verbose output\. Defaults to \fBfalse\fR, unless the \fB\-\-verbose\fR CLI flag is used\.
+.IP "\(bu" 4
+\fBversion\fR (\fBBUNDLE_VERSION\fR): The version of Bundler to use when running under Bundler environment\. Defaults to \fBlockfile\fR\. You can also specify \fBsystem\fR or \fBx\.y\.z\fR\. \fBlockfile\fR will use the Bundler version specified in the \fBGemfile\.lock\fR, \fBsystem\fR will use the system version of Bundler, and \fBx\.y\.z\fR will use the specified version of Bundler\.
+.IP "\(bu" 4
+\fBwith\fR (\fBBUNDLE_WITH\fR): A space\-separated or \fB:\fR\-separated list of groups whose gems bundler should install\.
+.IP "\(bu" 4
+\fBwithout\fR (\fBBUNDLE_WITHOUT\fR): A space\-separated or \fB:\fR\-separated list of groups whose gems bundler should not install\.
+.IP "" 0
+.SH "BUILD OPTIONS"
+You can use \fBbundle config\fR to give Bundler the flags to pass to the gem installer every time bundler tries to install a particular gem\.
+.P
+A very common example, the \fBmysql\fR gem, requires Snow Leopard users to pass configuration flags to \fBgem install\fR to specify where to find the \fBmysql_config\fR executable\.
+.IP "" 4
+.nf
+gem install mysql \-\- \-\-with\-mysql\-config=/usr/local/mysql/bin/mysql_config
+.fi
+.IP "" 0
+.P
+Since the specific location of that executable can change from machine to machine, you can specify these flags on a per\-machine basis\.
+.IP "" 4
+.nf
+bundle config set \-\-global build\.mysql \-\-with\-mysql\-config=/usr/local/mysql/bin/mysql_config
+.fi
+.IP "" 0
+.P
+After running this command, every time bundler needs to install the \fBmysql\fR gem, it will pass along the flags you specified\.
+.SH "LOCAL GIT REPOS"
+Bundler also allows you to work against a git repository locally instead of using the remote version\. This can be achieved by setting up a local override:
+.IP "" 4
+.nf
+bundle config set \-\-local local\.GEM_NAME /path/to/local/git/repository
+.fi
+.IP "" 0
+.P
+Important: This feature only works for gems that are specified with a git source in your Gemfile\. It does not work for gems installed from RubyGems or other sources\. The gem must be defined with \fBgit:\fR option pointing to a remote repository\.
+.P
+For example, if your Gemfile contains:
+.IP "" 4
+.nf
+gem "rack", git: "https://github\.com/rack/rack\.git", branch: "main"
+.fi
+.IP "" 0
+.P
+Then you can use a local Rack repository by running:
+.IP "" 4
+.nf
+bundle config set \-\-local local\.rack ~/Work/git/rack
+.fi
+.IP "" 0
+.P
+Now instead of checking out the remote git repository, the local override will be used\. Similar to a path source, every time the local git repository change, changes will be automatically picked up by Bundler\. This means a commit in the local git repo will update the revision in the \fBGemfile\.lock\fR to the local git repo revision\. This requires the same attention as git submodules\. Before pushing to the remote, you need to ensure the local override was pushed, otherwise you may point to a commit that only exists in your local machine\. You'll also need to CGI escape your usernames and passwords as well\.
+.P
+Bundler does many checks to ensure a developer won't work with invalid references\. Particularly, we force a developer to specify a branch in the \fBGemfile\fR in order to use this feature\. If the branch specified in the \fBGemfile\fR and the current branch in the local git repository do not match, Bundler will abort\. This ensures that a developer is always working against the correct branches, and prevents accidental locking to a different branch\.
+.P
+Finally, Bundler also ensures that the current revision in the \fBGemfile\.lock\fR exists in the local git repository\. By doing this, Bundler forces you to fetch the latest changes in the remotes\.
+.P
+If you need to temporarily use a local version of a gem that is normally installed from RubyGems (not from git), use a path source instead:
+.IP "" 4
+.nf
+gem "rack", path: "~/Work/git/rack"
+.fi
+.IP "" 0
+.SH "MIRRORS OF GEM SOURCES"
+Bundler supports overriding gem sources with mirrors\. This allows you to configure rubygems\.org as the gem source in your Gemfile while still using your mirror to fetch gems\.
+.IP "" 4
+.nf
+bundle config set \-\-global mirror\.SOURCE_URL MIRROR_URL
+.fi
+.IP "" 0
+.P
+For example, to use a mirror of https://rubygems\.org hosted at https://example\.org:
+.IP "" 4
+.nf
+bundle config set \-\-global mirror\.https://rubygems\.org https://example\.org
+.fi
+.IP "" 0
+.P
+Each mirror also provides a fallback timeout setting\. If the mirror does not respond within the fallback timeout, Bundler will try to use the original server instead of the mirror\.
+.IP "" 4
+.nf
+bundle config set \-\-global mirror\.SOURCE_URL\.fallback_timeout TIMEOUT
+.fi
+.IP "" 0
+.P
+For example, to fall back to rubygems\.org after 3 seconds:
+.IP "" 4
+.nf
+bundle config set \-\-global mirror\.https://rubygems\.org\.fallback_timeout 3
+.fi
+.IP "" 0
+.P
+The default fallback timeout is 0\.1 seconds, but the setting can currently only accept whole seconds (for example, 1, 15, or 30)\.
+.SH "CREDENTIALS FOR GEM SOURCES"
+Bundler allows you to configure credentials for any gem source, which allows you to avoid putting secrets into your Gemfile\.
+.IP "" 4
+.nf
+bundle config set \-\-global SOURCE_HOSTNAME USERNAME:PASSWORD
+.fi
+.IP "" 0
+.P
+For example, to save the credentials of user \fBclaudette\fR for the gem source at \fBgems\.longerous\.com\fR, you would run:
+.IP "" 4
+.nf
+bundle config set \-\-global gems\.longerous\.com claudette:s00pers3krit
+.fi
+.IP "" 0
+.P
+Or you can set the credentials as an environment variable like this:
+.IP "" 4
+.nf
+export BUNDLE_GEMS__LONGEROUS__COM="claudette:s00pers3krit"
+.fi
+.IP "" 0
+.P
+For gems with a git source with HTTP(S) URL you can specify credentials like so:
+.IP "" 4
+.nf
+bundle config set \-\-global https://github\.com/ruby/rubygems\.git username:password
+.fi
+.IP "" 0
+.P
+Or you can set the credentials as an environment variable like so:
+.IP "" 4
+.nf
+export BUNDLE_GITHUB__COM=username:password
+.fi
+.IP "" 0
+.P
+This is especially useful for private repositories on hosts such as GitHub, where you can use personal OAuth tokens:
+.IP "" 4
+.nf
+export BUNDLE_GITHUB__COM=abcd0123generatedtoken:x\-oauth\-basic
+.fi
+.IP "" 0
+.P
+Note that any configured credentials will be redacted by informative commands such as \fBbundle config list\fR or \fBbundle config get\fR, unless you use the \fB\-\-parseable\fR flag\. This is to avoid unintentionally leaking credentials when copy\-pasting bundler output\.
+.P
+Also note that to guarantee a sane mapping between valid environment variable names and valid host names, bundler makes the following transformations:
+.IP "\(bu" 4
+Any \fB\-\fR characters in a host name are mapped to a triple underscore (\fB___\fR) in the corresponding environment variable\.
+.IP "\(bu" 4
+Any \fB\.\fR characters in a host name are mapped to a double underscore (\fB__\fR) in the corresponding environment variable\.
+.IP "" 0
+.P
+This means that if you have a gem server named \fBmy\.gem\-host\.com\fR, you'll need to use the \fBBUNDLE_MY__GEM___HOST__COM\fR variable to configure credentials for it through ENV\.
+.SH "CONFIGURE BUNDLER DIRECTORIES"
+Bundler's home, cache and plugin directories and config file can be configured through environment variables\. The default location for Bundler's home directory is \fB~/\.bundle\fR, which all directories inherit from by default\. The following outlines the available environment variables and their default values
+.IP "" 4
+.nf
+BUNDLE_USER_HOME : $HOME/\.bundle
+BUNDLE_USER_CACHE : $BUNDLE_USER_HOME/cache
+BUNDLE_USER_CONFIG : $BUNDLE_USER_HOME/config
+BUNDLE_USER_PLUGIN : $BUNDLE_USER_HOME/plugin
+.fi
+.IP "" 0
+
diff --git a/lib/bundler/man/bundle-config.1.ronn b/lib/bundler/man/bundle-config.1.ronn
new file mode 100644
index 0000000000..72f891b428
--- /dev/null
+++ b/lib/bundler/man/bundle-config.1.ronn
@@ -0,0 +1,463 @@
+bundle-config(1) -- Set bundler configuration options
+=====================================================
+
+## SYNOPSIS
+
+`bundle config` [list]<br>
+`bundle config` [get [--local|--global]] NAME<br>
+`bundle config` [set [--local|--global]] NAME VALUE<br>
+`bundle config` unset [--local|--global] NAME
+
+## DESCRIPTION
+
+This command allows you to interact with Bundler's configuration system.
+
+Bundler loads configuration settings in this order:
+
+1. Local config (`<project_root>/.bundle/config` or `$BUNDLE_APP_CONFIG/config`)
+2. Environmental variables (`ENV`)
+3. Global config (`~/.bundle/config`)
+4. Bundler default config
+
+Executing `bundle` with the `BUNDLE_IGNORE_CONFIG` environment variable set will
+cause it to ignore all configuration.
+
+## SUB-COMMANDS
+
+### list (default command)
+
+Executing `bundle config list` will print a list of all bundler
+configuration for the current bundle, and where that configuration
+was set.
+
+### get
+
+Executing `bundle config get <name>` will print the value of that configuration
+setting, and all locations where it was set.
+
+**OPTIONS**
+
+* `--local`:
+  Get configuration from configuration file for the local application, namely,
+  `<project_root>/.bundle/config`, or `$BUNDLE_APP_CONFIG/config` if
+  `BUNDLE_APP_CONFIG` is set.
+
+* `--global`:
+  Get configuration from configuration file global to all bundles executed as
+  the current user, namely, from `~/.bundle/config`.
+
+### set
+
+Executing `bundle config set <name> <value>` defaults to setting `local`
+configuration if executing from within a local application, otherwise it will
+set `global` configuration.
+
+**OPTIONS**
+
+* `--local`:
+  Executing `bundle config set --local <name> <value>` will set that configuration
+  in the directory for the local application. The configuration will be stored in
+  `<project_root>/.bundle/config`. If `BUNDLE_APP_CONFIG` is set, the configuration
+  will be stored in `$BUNDLE_APP_CONFIG/config`.
+
+* `--global`:
+  Executing `bundle config set --global <name> <value>` will set that
+  configuration to the value specified for all bundles executed as the current
+  user. The configuration will be stored in `~/.bundle/config`. If <name> already
+  is set, <name> will be overridden and user will be warned.
+
+### unset
+
+Executing `bundle config unset <name>` will delete the configuration in both
+local and global sources.
+
+**OPTIONS**
+
+* `--local`:
+  Executing `bundle config unset --local <name>` will delete the configuration
+  only from the local application.
+
+* `--global`:
+  Executing `bundle config unset --global <name>` will delete the configuration
+  only from the user configuration.
+
+## CONFIGURATION KEYS
+
+Configuration keys in bundler have two forms: the canonical form and the
+environment variable form.
+
+For instance, passing the `--without` flag to [bundle install(1)](bundle-install.1.html)
+prevents Bundler from installing certain groups specified in the Gemfile(5). Bundler
+persists this value in `app/.bundle/config` so that calls to `Bundler.setup`
+do not try to find gems from the `Gemfile` that you didn't install. Additionally,
+subsequent calls to [bundle install(1)](bundle-install.1.html) remember this setting
+and skip those groups.
+
+The canonical form of this configuration is `"without"`. To convert the canonical
+form to the environment variable form, capitalize it, and prepend `BUNDLE_`. The
+environment variable form of `"without"` is `BUNDLE_WITHOUT`.
+
+Any periods in the configuration keys must be replaced with two underscores when
+setting it via environment variables. The configuration key `local.rack` becomes
+the environment variable `BUNDLE_LOCAL__RACK`.
+
+## LIST OF AVAILABLE KEYS
+
+The following is a list of all configuration keys and their purpose. You can
+learn more about their operation in [bundle install(1)](bundle-install.1.html).
+
+* `api_request_size` (`BUNDLE_API_REQUEST_SIZE`):
+   Configure how many dependencies to fetch when resolving the specifications.
+   This configuration is only used when fetching specifications from RubyGems
+   servers that didn't implement the Compact Index API.
+   Defaults to 100.
+* `auto_install` (`BUNDLE_AUTO_INSTALL`):
+   Automatically run `bundle install` when gems are missing.
+* `bin` (`BUNDLE_BIN`):
+   If configured, `bundle binstubs` will install executables from gems in the
+   bundle to the specified directory. Otherwise it will create them in a `bin`
+   directory relative to the Gemfile directory. These executables run in
+   Bundler's context. If used, you might add this directory to your
+   environment's `PATH` variable. For instance, if the `rails` gem comes with a
+   `rails` executable, `bundle binstubs` will create a `bin/rails` executable
+   that ensures that all referred dependencies will be resolved using the
+   bundled gems.
+* `cache_all` (`BUNDLE_CACHE_ALL`):
+   Cache all gems, including path and git gems. This needs to be explicitly
+   before bundler 4, but will be the default on bundler 4.
+* `cache_all_platforms` (`BUNDLE_CACHE_ALL_PLATFORMS`):
+   Cache gems for all platforms.
+* `cache_path` (`BUNDLE_CACHE_PATH`):
+   The directory that bundler will place cached gems in when running
+   <code>bundle package</code>, and that bundler will look in when installing gems.
+   Defaults to `vendor/cache`.
+* `clean` (`BUNDLE_CLEAN`):
+   Whether Bundler should run `bundle clean` automatically after
+   `bundle install`. Defaults to `true` in Bundler 4, as long as `path` is not
+   explicitly configured.
+* `console` (`BUNDLE_CONSOLE`):
+   The console that `bundle console` starts. Defaults to `irb`.
+* `cooldown` (`BUNDLE_COOLDOWN`):
+   Number of days a published gem version must age before bundler will
+   resolve to it. Defaults to unset (no cooldown). Pass `0` to disable
+   cooldown for an individual run.
+
+   The effective cooldown for any given gem is resolved from three
+   layers, highest precedence first:
+
+     1. CLI flag `--cooldown N` on `install`, `update`, `add`, and
+        `outdated`.
+     2. This setting (`bundle config set cooldown N` or
+        `BUNDLE_COOLDOWN=N`).
+     3. The per-source `cooldown:` keyword in the Gemfile, such as
+        `source "https://rubygems.org", cooldown: 7`.
+
+   The CLI flag and this setting apply uniformly to every source,
+   including ones declared with their own `cooldown:` value. To keep a
+   private registry permanently exempt while still cooling down public
+   gems, declare `source "https://internal", cooldown: 0` in the
+   Gemfile; remember that `--cooldown N` on the command line will
+   still override it for that single run.
+
+   Cooldown filtering depends on the gem server providing a per-version
+   `created_at` timestamp in the v2 compact-index format. Versions
+   without that metadata - older gem servers, historical entries that
+   predate the v2 cutover on `rubygems.org`, or private registries that
+   still emit the v1 format - are treated as outside the cooldown
+   window and remain resolvable. If you rely on cooldown for
+   supply-chain protection, confirm that the gem server emits
+   `created_at` in its `/info/<gem>` responses.
+* `default_cli_command` (`BUNDLE_DEFAULT_CLI_COMMAND`):
+   The command that running `bundle` without arguments should run. Defaults to
+   `cli_help` since Bundler 4, but can also be `install` which was the previous
+   default.
+* `deployment` (`BUNDLE_DEPLOYMENT`):
+   Equivalent to setting `frozen` to `true` and `path` to `vendor/bundle`.
+* `disable_checksum_validation` (`BUNDLE_DISABLE_CHECKSUM_VALIDATION`):
+   Allow installing gems even if they do not match the checksum provided by
+   RubyGems.
+* `disable_exec_load` (`BUNDLE_DISABLE_EXEC_LOAD`):
+   Stop Bundler from using `load` to launch an executable in-process in
+   `bundle exec`.
+* `disable_local_branch_check` (`BUNDLE_DISABLE_LOCAL_BRANCH_CHECK`):
+   Allow Bundler to use a local git override without a branch specified in the
+   Gemfile.
+* `disable_local_revision_check` (`BUNDLE_DISABLE_LOCAL_REVISION_CHECK`):
+   Allow Bundler to use a local git override without checking if the revision
+   present in the lockfile is present in the repository.
+* `disable_shared_gems` (`BUNDLE_DISABLE_SHARED_GEMS`):
+   Stop Bundler from accessing gems installed to RubyGems' normal location.
+* `disable_version_check` (`BUNDLE_DISABLE_VERSION_CHECK`):
+   Stop Bundler from checking if a newer Bundler version is available on
+   rubygems.org.
+* `force_ruby_platform` (`BUNDLE_FORCE_RUBY_PLATFORM`):
+   Ignore the current machine's platform and install only `ruby` platform gems.
+   As a result, gems with native extensions will be compiled from source.
+* `frozen` (`BUNDLE_FROZEN`):
+   Disallow any automatic changes to `Gemfile.lock`. Bundler commands will
+   be blocked unless the lockfile can be installed exactly as written.
+   Usually this will happen when changing the `Gemfile` manually and forgetting
+   to update the lockfile through `bundle lock` or `bundle install`.
+* `gem.github_username` (`BUNDLE_GEM__GITHUB_USERNAME`):
+   Sets a GitHub username or organization to be used in the `README` and `.gemspec` files
+   when you create a new gem via `bundle gem` command. It can be overridden by passing an
+   explicit `--github-username` flag to `bundle gem`.
+* `gem.push_key` (`BUNDLE_GEM__PUSH_KEY`):
+   Sets the `--key` parameter for `gem push` when using the `rake release`
+   command with a private gemstash server.
+* `gemfile` (`BUNDLE_GEMFILE`):
+   The name of the file that bundler should use as the `Gemfile`. This location
+   of this file also sets the root of the project, which is used to resolve
+   relative paths in the `Gemfile`, among other things. By default, bundler
+   will search up from the current working directory until it finds a
+   `Gemfile`.
+* `global_gem_cache` (`BUNDLE_GLOBAL_GEM_CACHE`):
+   Whether Bundler should cache all gems and compiled extensions globally,
+   rather than locally to the configured installation path.
+* `ignore_funding_requests` (`BUNDLE_IGNORE_FUNDING_REQUESTS`):
+   When set, no funding requests will be printed.
+* `ignore_messages` (`BUNDLE_IGNORE_MESSAGES`):
+   When set, no post install messages will be printed. To silence a single gem,
+   use dot notation like `ignore_messages.httparty true`.
+* `init_gems_rb` (`BUNDLE_INIT_GEMS_RB`):
+   Generate a `gems.rb` instead of a `Gemfile` when running `bundle init`.
+* `jobs` (`BUNDLE_JOBS`):
+   The number of gems Bundler can download and install in parallel.
+   Defaults to the number of available processors.
+* `lockfile` (`BUNDLE_LOCKFILE`):
+   The path to the lockfile that bundler should use. By default, Bundler adds
+   `.lock` to the end of the `gemfile` entry. Can be set to `false` in the
+   Gemfile to disable lockfile creation entirely (see gemfile(5)).
+* `lockfile_checksums` (`BUNDLE_LOCKFILE_CHECKSUMS`):
+   Whether Bundler should include a checksums section in new lockfiles, to protect from compromised gem sources. Defaults to true.
+* `no_build_extension` (`BUNDLE_NO_BUILD_EXTENSION`):
+   Whether Bundler should skip building native extensions during installation.
+   When set, gems are installed without compiling their C extensions.
+   To build extensions later, unset this setting and run `bundle pristine <gem>`.
+* `no_install` (`BUNDLE_NO_INSTALL`):
+   Whether `bundle package` should skip installing gems.
+* `no_install_plugin` (`BUNDLE_NO_INSTALL_PLUGIN`):
+   Whether Bundler should skip installing RubyGems plugins during installation.
+   When set, plugin files are not written to the plugins directory.
+   To install plugins later, unset this setting and run `bundle pristine <gem>`.
+* `no_prune` (`BUNDLE_NO_PRUNE`):
+   Whether Bundler should leave outdated gems unpruned when caching.
+* `only` (`BUNDLE_ONLY`):
+   A space-separated list of groups to install only gems of the specified groups.
+   Please check carefully if you want to install also gems without a group, because
+   they get put inside `default` group. For example `only test:default` will install
+   all gems specified in test group and without one.
+* `path` (`BUNDLE_PATH`):
+   The location on disk where all gems in your bundle will be located regardless
+   of `$GEM_HOME` or `$GEM_PATH` values. Bundle gems not found in this location
+   will be installed by `bundle install`. When not set, Bundler install by
+   default to a `.bundle` directory relative to repository root in Bundler 4,
+   and to the default system path (`Gem.dir`) before Bundler 4. That means that
+   before Bundler 4, Bundler shares this location with Rubygems, and `gem
+   install ...` will have gems installed in the same location and therefore,
+   gems installed without `path` set will show up by calling `gem list`. This
+   will not be the case in Bundler 4.
+* `path.system` (`BUNDLE_PATH__SYSTEM`):
+   Whether Bundler will install gems into the default system path (`Gem.dir`).
+* `plugins` (`BUNDLE_PLUGINS`):
+   Enable Bundler's experimental plugin system.
+* `prefer_patch` (`BUNDLE_PREFER_PATCH`):
+   Prefer updating only to next patch version during updates. Makes `bundle update` calls equivalent to `bundler update --patch`.
+* `redirect` (`BUNDLE_REDIRECT`):
+   The number of redirects allowed for network requests. Defaults to `5`.
+* `retry` (`BUNDLE_RETRY`):
+   The number of times to retry failed network requests. Defaults to `3`.
+* `shebang` (`BUNDLE_SHEBANG`):
+   The program name that should be invoked for generated binstubs. Defaults to
+   the ruby install name used to generate the binstub.
+* `silence_deprecations` (`BUNDLE_SILENCE_DEPRECATIONS`):
+   Whether Bundler should silence deprecation warnings for behavior that will
+   be changed in the next major version.
+* `silence_root_warning` (`BUNDLE_SILENCE_ROOT_WARNING`):
+   Silence the warning Bundler prints when installing gems as root.
+* `simulate_version` (`BUNDLE_SIMULATE_VERSION`):
+   The virtual version Bundler should use for activating feature flags. Can be
+   used to simulate all the new functionality that will be enabled in a future
+   major version.
+* `ssl_ca_cert` (`BUNDLE_SSL_CA_CERT`):
+   Path to a designated CA certificate file or folder containing multiple
+   certificates for trusted CAs in PEM format.
+* `ssl_client_cert` (`BUNDLE_SSL_CLIENT_CERT`):
+   Path to a designated file containing a X.509 client certificate
+   and key in PEM format.
+* `ssl_verify_mode` (`BUNDLE_SSL_VERIFY_MODE`):
+   The SSL verification mode Bundler uses when making HTTPS requests.
+   Defaults to verify peer.
+* `system_bindir` (`BUNDLE_SYSTEM_BINDIR`):
+   The location where RubyGems installs binstubs. Defaults to `Gem.bindir`.
+* `timeout` (`BUNDLE_TIMEOUT`):
+   The seconds allowed before timing out for network requests. Defaults to `10`.
+* `update_requires_all_flag` (`BUNDLE_UPDATE_REQUIRES_ALL_FLAG`):
+   Require passing `--all` to `bundle update` when everything should be updated,
+   and disallow passing no options to `bundle update`.
+* `user_agent` (`BUNDLE_USER_AGENT`):
+   The custom user agent fragment Bundler includes in API requests.
+* `verbose` (`BUNDLE_VERBOSE`):
+   Whether Bundler should print verbose output. Defaults to `false`, unless the
+   `--verbose` CLI flag is used.
+* `version` (`BUNDLE_VERSION`):
+   The version of Bundler to use when running under Bundler environment.
+   Defaults to `lockfile`. You can also specify `system` or `x.y.z`.
+   `lockfile` will use the Bundler version specified in the `Gemfile.lock`,
+   `system` will use the system version of Bundler, and `x.y.z` will use
+   the specified version of Bundler.
+* `with` (`BUNDLE_WITH`):
+   A space-separated or `:`-separated list of groups whose gems bundler should install.
+* `without` (`BUNDLE_WITHOUT`):
+   A space-separated or `:`-separated list of groups whose gems bundler should not install.
+
+## BUILD OPTIONS
+
+You can use `bundle config` to give Bundler the flags to pass to the gem
+installer every time bundler tries to install a particular gem.
+
+A very common example, the `mysql` gem, requires Snow Leopard users to
+pass configuration flags to `gem install` to specify where to find the
+`mysql_config` executable.
+
+    gem install mysql -- --with-mysql-config=/usr/local/mysql/bin/mysql_config
+
+Since the specific location of that executable can change from machine
+to machine, you can specify these flags on a per-machine basis.
+
+    bundle config set --global build.mysql --with-mysql-config=/usr/local/mysql/bin/mysql_config
+
+After running this command, every time bundler needs to install the
+`mysql` gem, it will pass along the flags you specified.
+
+## LOCAL GIT REPOS
+
+Bundler also allows you to work against a git repository locally
+instead of using the remote version. This can be achieved by setting
+up a local override:
+
+    bundle config set --local local.GEM_NAME /path/to/local/git/repository
+
+Important: This feature only works for gems that are specified with a git
+source in your Gemfile. It does not work for gems installed from RubyGems
+or other sources. The gem must be defined with `git:` option pointing to a
+remote repository.
+
+For example, if your Gemfile contains:
+
+    gem "rack", git: "https://github.com/rack/rack.git", branch: "main"
+
+Then you can use a local Rack repository by running:
+
+    bundle config set --local local.rack ~/Work/git/rack
+
+Now instead of checking out the remote git repository, the local
+override will be used. Similar to a path source, every time the local
+git repository change, changes will be automatically picked up by
+Bundler. This means a commit in the local git repo will update the
+revision in the `Gemfile.lock` to the local git repo revision. This
+requires the same attention as git submodules. Before pushing to
+the remote, you need to ensure the local override was pushed, otherwise
+you may point to a commit that only exists in your local machine.
+You'll also need to CGI escape your usernames and passwords as well.
+
+Bundler does many checks to ensure a developer won't work with
+invalid references. Particularly, we force a developer to specify
+a branch in the `Gemfile` in order to use this feature. If the branch
+specified in the `Gemfile` and the current branch in the local git
+repository do not match, Bundler will abort. This ensures that
+a developer is always working against the correct branches, and prevents
+accidental locking to a different branch.
+
+Finally, Bundler also ensures that the current revision in the
+`Gemfile.lock` exists in the local git repository. By doing this, Bundler
+forces you to fetch the latest changes in the remotes.
+
+If you need to temporarily use a local version of a gem that is normally
+installed from RubyGems (not from git), use a path source instead:
+
+    gem "rack", path: "~/Work/git/rack"
+
+## MIRRORS OF GEM SOURCES
+
+Bundler supports overriding gem sources with mirrors. This allows you to
+configure rubygems.org as the gem source in your Gemfile while still using your
+mirror to fetch gems.
+
+    bundle config set --global mirror.SOURCE_URL MIRROR_URL
+
+For example, to use a mirror of https://rubygems.org hosted at https://example.org:
+
+    bundle config set --global mirror.https://rubygems.org https://example.org
+
+Each mirror also provides a fallback timeout setting. If the mirror does not
+respond within the fallback timeout, Bundler will try to use the original
+server instead of the mirror.
+
+    bundle config set --global mirror.SOURCE_URL.fallback_timeout TIMEOUT
+
+For example, to fall back to rubygems.org after 3 seconds:
+
+    bundle config set --global mirror.https://rubygems.org.fallback_timeout 3
+
+The default fallback timeout is 0.1 seconds, but the setting can currently
+only accept whole seconds (for example, 1, 15, or 30).
+
+## CREDENTIALS FOR GEM SOURCES
+
+Bundler allows you to configure credentials for any gem source, which allows
+you to avoid putting secrets into your Gemfile.
+
+    bundle config set --global SOURCE_HOSTNAME USERNAME:PASSWORD
+
+For example, to save the credentials of user `claudette` for the gem source at
+`gems.longerous.com`, you would run:
+
+    bundle config set --global gems.longerous.com claudette:s00pers3krit
+
+Or you can set the credentials as an environment variable like this:
+
+    export BUNDLE_GEMS__LONGEROUS__COM="claudette:s00pers3krit"
+
+For gems with a git source with HTTP(S) URL you can specify credentials like so:
+
+    bundle config set --global https://github.com/ruby/rubygems.git username:password
+
+Or you can set the credentials as an environment variable like so:
+
+    export BUNDLE_GITHUB__COM=username:password
+
+This is especially useful for private repositories on hosts such as GitHub,
+where you can use personal OAuth tokens:
+
+    export BUNDLE_GITHUB__COM=abcd0123generatedtoken:x-oauth-basic
+
+Note that any configured credentials will be redacted by informative commands
+such as `bundle config list` or `bundle config get`, unless you use the
+`--parseable` flag. This is to avoid unintentionally leaking credentials when
+copy-pasting bundler output.
+
+Also note that to guarantee a sane mapping between valid environment variable
+names and valid host names, bundler makes the following transformations:
+
+* Any `-` characters in a host name are mapped to a triple underscore (`___`) in the
+  corresponding environment variable.
+
+* Any `.` characters in a host name are mapped to a double underscore (`__`) in the
+  corresponding environment variable.
+
+This means that if you have a gem server named `my.gem-host.com`, you'll need to
+use the `BUNDLE_MY__GEM___HOST__COM` variable to configure credentials for it
+through ENV.
+
+## CONFIGURE BUNDLER DIRECTORIES
+
+Bundler's home, cache and plugin directories and config file can be configured
+through environment variables. The default location for Bundler's home directory is
+`~/.bundle`, which all directories inherit from by default. The following
+outlines the available environment variables and their default values
+
+    BUNDLE_USER_HOME : $HOME/.bundle
+    BUNDLE_USER_CACHE : $BUNDLE_USER_HOME/cache
+    BUNDLE_USER_CONFIG : $BUNDLE_USER_HOME/config
+    BUNDLE_USER_PLUGIN : $BUNDLE_USER_HOME/plugin
diff --git a/lib/bundler/man/bundle-console.1 b/lib/bundler/man/bundle-console.1
new file mode 100644
index 0000000000..5d3f65365f
--- /dev/null
+++ b/lib/bundler/man/bundle-console.1
@@ -0,0 +1,33 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-CONSOLE" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-console\fR \- Open an IRB session with the bundle pre\-loaded
+.SH "SYNOPSIS"
+\fBbundle console\fR [GROUP]
+.SH "DESCRIPTION"
+Starts an interactive Ruby console session in the context of the current bundle\.
+.P
+If no \fBGROUP\fR is specified, all gems in the \fBdefault\fR group in the Gemfile(5) \fIhttps://bundler\.io/man/gemfile\.5\.html\fR are preliminarily loaded\.
+.P
+If \fBGROUP\fR is specified, all gems in the given group in the Gemfile in addition to the gems in \fBdefault\fR group are loaded\. Even if the given group does not exist in the Gemfile, IRB console starts without any warning or error\.
+.P
+The environment variable \fBBUNDLE_CONSOLE\fR or \fBbundle config set console\fR can be used to change the shell from the following:
+.IP "\(bu" 4
+\fBirb\fR (default)
+.IP "\(bu" 4
+\fBpry\fR (https://github\.com/pry/pry)
+.IP "\(bu" 4
+\fBripl\fR (https://github\.com/cldwalker/ripl)
+.IP "" 0
+.P
+\fBbundle console\fR uses irb by default\. An alternative Pry or Ripl can be used with \fBbundle console\fR by adjusting the \fBconsole\fR Bundler setting\. Also make sure that \fBpry\fR or \fBripl\fR is in your Gemfile\.
+.SH "EXAMPLE"
+.nf
+$ bundle config set console pry
+$ bundle console
+Resolving dependencies\|\.\|\.\|\.
+[1] pry(main)>
+.fi
+.SH "SEE ALSO"
+Gemfile(5) \fIhttps://bundler\.io/man/gemfile\.5\.html\fR
diff --git a/lib/bundler/man/bundle-console.1.ronn b/lib/bundler/man/bundle-console.1.ronn
new file mode 100644
index 0000000000..ed842ae1c3
--- /dev/null
+++ b/lib/bundler/man/bundle-console.1.ronn
@@ -0,0 +1,39 @@
+bundle-console(1) -- Open an IRB session with the bundle pre-loaded
+===================================================================
+
+## SYNOPSIS
+
+`bundle console` [GROUP]
+
+## DESCRIPTION
+
+Starts an interactive Ruby console session in the context of the current bundle.
+
+If no `GROUP` is specified, all gems in the `default` group in the [Gemfile(5)](https://bundler.io/man/gemfile.5.html) are
+preliminarily loaded.
+
+If `GROUP` is specified, all gems in the given group in the Gemfile in addition
+to the gems in `default` group are loaded. Even if the given group does not
+exist in the Gemfile, IRB console starts without any warning or error.
+
+The environment variable `BUNDLE_CONSOLE` or `bundle config set console` can be used to change
+the shell from the following:
+
+* `irb` (default)
+* `pry` (https://github.com/pry/pry)
+* `ripl` (https://github.com/cldwalker/ripl)
+
+`bundle console` uses irb by default. An alternative Pry or Ripl can be used with
+`bundle console` by adjusting the `console` Bundler setting. Also make sure that
+`pry` or `ripl` is in your Gemfile.
+
+## EXAMPLE
+
+    $ bundle config set console pry
+    $ bundle console
+    Resolving dependencies...
+    [1] pry(main)>
+
+## SEE ALSO
+
+[Gemfile(5)](https://bundler.io/man/gemfile.5.html)
diff --git a/lib/bundler/man/bundle-doctor.1 b/lib/bundler/man/bundle-doctor.1
new file mode 100644
index 0000000000..4c59871b66
--- /dev/null
+++ b/lib/bundler/man/bundle-doctor.1
@@ -0,0 +1,69 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-DOCTOR" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-doctor\fR \- Checks the bundle for common problems
+.SH "SYNOPSIS"
+\fBbundle doctor [diagnose]\fR [\-\-quiet] [\-\-gemfile=GEMFILE] [\-\-ssl]
+.br
+\fBbundle doctor ssl\fR [\-\-host=HOST] [\-\-tls\-version=TLS\-VERSION] [\-\-verify\-mode=VERIFY\-MODE]
+.br
+\fBbundle doctor\fR help [COMMAND]
+.SH "DESCRIPTION"
+You can diagnose common Bundler problems with this command such as checking gem environment or SSL/TLS issue\.
+.SH "SUB\-COMMANDS"
+.SS "diagnose (default command)"
+Checks your Gemfile and gem environment for common problems\. If issues are detected, Bundler prints them and exits status 1\. Otherwise, Bundler prints a success message and exits status 0\.
+.P
+Examples of common problems caught include:
+.IP "\(bu" 4
+Invalid Bundler settings
+.IP "\(bu" 4
+Mismatched Ruby versions
+.IP "\(bu" 4
+Mismatched platforms
+.IP "\(bu" 4
+Uninstalled gems
+.IP "\(bu" 4
+Missing dependencies
+.IP "" 0
+.P
+\fBOPTIONS\fR
+.TP
+\fB\-\-quiet\fR
+Only output warnings and errors\.
+.TP
+\fB\-\-gemfile=GEMFILE\fR
+The location of the Gemfile(5) which Bundler should use\. This defaults to a Gemfile(5) in the current working directory\. In general, Bundler will assume that the location of the Gemfile(5) is also the project's root and will try to find \fBGemfile\.lock\fR and \fBvendor/cache\fR relative to this location\.
+.TP
+\fB\-\-ssl\fR
+Diagnose common SSL problems when connecting to https://rubygems\.org\.
+.IP
+This flag runs the \fBbundle doctor ssl\fR subcommand with default values underneath\.
+.SS "ssl"
+If you've experienced issues related to SSL certificates and/or TLS versions while connecting to https://rubygems\.org, this command can help troubleshoot common problems\. The diagnostic will perform a few checks such as:
+.IP "\(bu" 4
+Verify the Ruby OpenSSL version installed on your system\.
+.IP "\(bu" 4
+Check the OpenSSL library version used for compilation\.
+.IP "\(bu" 4
+Ensure CA certificates are correctly setup on your machine\.
+.IP "\(bu" 4
+Open a TLS connection and verify the outcome\.
+.IP "" 0
+.P
+\fBOPTIONS\fR
+.TP
+\fB\-\-host=HOST\fR
+Perform the diagnostic on HOST\. Defaults to \fBrubygems\.org\fR\.
+.TP
+\fB\-\-tls\-version=TLS\-VERSION\fR
+Specify the TLS version when opening the connection to HOST\.
+.IP
+Accepted values are: \fB1\.1\fR or \fB1\.2\fR\.
+.TP
+\fB\-\-verify\-mode=VERIFY\-MODE\fR
+Specify the TLS verify mode when opening the connection to HOST\. Defaults to \fBSSL_VERIFY_PEER\fR\.
+.IP
+Accepted values are: \fBCLIENT_ONCE\fR, \fBFAIL_IF_NO_PEER_CERT\fR, \fBNONE\fR, \fBPEER\fR\.
+
diff --git a/lib/bundler/man/bundle-doctor.1.ronn b/lib/bundler/man/bundle-doctor.1.ronn
new file mode 100644
index 0000000000..7495099ff5
--- /dev/null
+++ b/lib/bundler/man/bundle-doctor.1.ronn
@@ -0,0 +1,77 @@
+bundle-doctor(1) -- Checks the bundle for common problems
+=========================================================
+
+## SYNOPSIS
+
+`bundle doctor [diagnose]` [--quiet]
+                           [--gemfile=GEMFILE]
+                           [--ssl]<br>
+`bundle doctor ssl` [--host=HOST]
+                    [--tls-version=TLS-VERSION]
+                    [--verify-mode=VERIFY-MODE]<br>
+`bundle doctor` help [COMMAND]
+
+## DESCRIPTION
+
+You can diagnose common Bundler problems with this command such as checking gem environment or SSL/TLS issue.
+
+## SUB-COMMANDS
+
+### diagnose (default command)
+
+Checks your Gemfile and gem environment for common problems. If issues
+are detected, Bundler prints them and exits status 1. Otherwise,
+Bundler prints a success message and exits status 0.
+
+Examples of common problems caught include:
+
+* Invalid Bundler settings
+* Mismatched Ruby versions
+* Mismatched platforms
+* Uninstalled gems
+* Missing dependencies
+
+**OPTIONS**
+
+* `--quiet`:
+  Only output warnings and errors.
+
+* `--gemfile=GEMFILE`:
+  The location of the Gemfile(5) which Bundler should use. This defaults
+  to a Gemfile(5) in the current working directory. In general, Bundler
+  will assume that the location of the Gemfile(5) is also the project's
+  root and will try to find `Gemfile.lock` and `vendor/cache` relative
+  to this location.
+
+* `--ssl`:
+  Diagnose common SSL problems when connecting to https://rubygems.org.
+
+  This flag runs the `bundle doctor ssl` subcommand with default values
+  underneath.
+
+### ssl
+
+If you've experienced issues related to SSL certificates and/or TLS versions while connecting
+to https://rubygems.org, this command can help troubleshoot common problems.
+The diagnostic will perform a few checks such as:
+
+* Verify the Ruby OpenSSL version installed on your system.
+* Check the OpenSSL library version used for compilation.
+* Ensure CA certificates are correctly setup on your machine.
+* Open a TLS connection and verify the outcome.
+
+**OPTIONS**
+
+* `--host=HOST`:
+  Perform the diagnostic on HOST. Defaults to `rubygems.org`.
+
+* `--tls-version=TLS-VERSION`:
+  Specify the TLS version when opening the connection to HOST.
+
+  Accepted values are: `1.1` or `1.2`.
+
+* `--verify-mode=VERIFY-MODE`:
+  Specify the TLS verify mode when opening the connection to HOST.
+  Defaults to `SSL_VERIFY_PEER`.
+
+  Accepted values are: `CLIENT_ONCE`, `FAIL_IF_NO_PEER_CERT`, `NONE`, `PEER`.
diff --git a/lib/bundler/man/bundle-env.1 b/lib/bundler/man/bundle-env.1
new file mode 100644
index 0000000000..25fcb64891
--- /dev/null
+++ b/lib/bundler/man/bundle-env.1
@@ -0,0 +1,9 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-ENV" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-env\fR \- Print information about the environment Bundler is running under
+.SH "SYNOPSIS"
+\fBbundle env\fR
+.SH "DESCRIPTION"
+Prints information about the environment Bundler is running under\.
diff --git a/lib/bundler/man/bundle-env.1.ronn b/lib/bundler/man/bundle-env.1.ronn
new file mode 100644
index 0000000000..c2df9c29c2
--- /dev/null
+++ b/lib/bundler/man/bundle-env.1.ronn
@@ -0,0 +1,10 @@
+bundle-env(1) -- Print information about the environment Bundler is running under
+=================================================================================
+
+## SYNOPSIS
+
+`bundle env`
+
+## DESCRIPTION
+
+Prints information about the environment Bundler is running under.
diff --git a/lib/bundler/man/bundle-exec.1 b/lib/bundler/man/bundle-exec.1
new file mode 100644
index 0000000000..c3a6a09d57
--- /dev/null
+++ b/lib/bundler/man/bundle-exec.1
@@ -0,0 +1,104 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-EXEC" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-exec\fR \- Execute a command in the context of the bundle
+.SH "SYNOPSIS"
+\fBbundle exec\fR [\-\-gemfile=GEMFILE] \fIcommand\fR
+.SH "DESCRIPTION"
+This command executes the command, making all gems specified in the [\fBGemfile(5)\fR][Gemfile(5)] available to \fBrequire\fR in Ruby programs\.
+.P
+Essentially, if you would normally have run something like \fBrspec spec/my_spec\.rb\fR, and you want to use the gems specified in the [\fBGemfile(5)\fR][Gemfile(5)] and installed via bundle install(1) \fIbundle\-install\.1\.html\fR, you should run \fBbundle exec rspec spec/my_spec\.rb\fR\.
+.P
+Note that \fBbundle exec\fR does not require that an executable is available on your shell's \fB$PATH\fR\.
+.SH "OPTIONS"
+.TP
+\fB\-\-gemfile=GEMFILE\fR
+Use the specified gemfile instead of [\fBGemfile(5)\fR][Gemfile(5)]\.
+.SH "BUNDLE INSTALL \-\-BINSTUBS"
+If you use the \fB\-\-binstubs\fR flag in bundle install(1) \fIbundle\-install\.1\.html\fR, Bundler will automatically create a directory (which defaults to \fBapp_root/bin\fR) containing all of the executables available from gems in the bundle\.
+.P
+After using \fB\-\-binstubs\fR, \fBbin/rspec spec/my_spec\.rb\fR is identical to \fBbundle exec rspec spec/my_spec\.rb\fR\.
+.SH "ENVIRONMENT MODIFICATIONS"
+\fBbundle exec\fR makes a number of changes to the shell environment, then executes the command you specify in full\.
+.IP "\(bu" 4
+make sure that it's still possible to shell out to \fBbundle\fR from inside a command invoked by \fBbundle exec\fR (using \fB$BUNDLE_BIN_PATH\fR)
+.IP "\(bu" 4
+put the directory containing executables (like \fBrails\fR, \fBrspec\fR, \fBrackup\fR) for your bundle on \fB$PATH\fR
+.IP "\(bu" 4
+make sure that if bundler is invoked in the subshell, it uses the same \fBGemfile\fR (by setting \fBBUNDLE_GEMFILE\fR)
+.IP "\(bu" 4
+add \fB\-rbundler/setup\fR to \fB$RUBYOPT\fR, which makes sure that Ruby programs invoked in the subshell can see the gems in the bundle
+.IP "" 0
+.P
+It also modifies Rubygems:
+.IP "\(bu" 4
+disallow loading additional gems not in the bundle
+.IP "\(bu" 4
+modify the \fBgem\fR method to be a no\-op if a gem matching the requirements is in the bundle, and to raise a \fBGem::LoadError\fR if it's not
+.IP "\(bu" 4
+Define \fBGem\.refresh\fR to be a no\-op, since the source index is always frozen when using bundler, and to prevent gems from the system leaking into the environment
+.IP "\(bu" 4
+Override \fBGem\.bin_path\fR to use the gems in the bundle, making system executables work
+.IP "\(bu" 4
+Add all gems in the bundle into Gem\.loaded_specs
+.IP "" 0
+.P
+Finally, \fBbundle exec\fR also implicitly modifies \fBGemfile\.lock\fR if the lockfile and the Gemfile do not match\. Bundler needs the Gemfile to determine things such as a gem's groups, \fBautorequire\fR, and platforms, etc\., and that information isn't stored in the lockfile\. The Gemfile and lockfile must be synced in order to \fBbundle exec\fR successfully, so \fBbundle exec\fR updates the lockfile beforehand\.
+.SS "Loading"
+By default, when attempting to \fBbundle exec\fR to a file with a ruby shebang, Bundler will \fBKernel\.load\fR that file instead of using \fBKernel\.exec\fR\. For the vast majority of cases, this is a performance improvement\. In a rare few cases, this could cause some subtle side\-effects (such as dependence on the exact contents of \fB$0\fR or \fB__FILE__\fR) and the optimization can be disabled by enabling the \fBdisable_exec_load\fR setting\.
+.SS "Shelling out"
+Any Ruby code that opens a subshell (like \fBsystem\fR, backticks, or \fB%x{}\fR) will automatically use the current Bundler environment\. If you need to shell out to a Ruby command that is not part of your current bundle, use the \fBwith_unbundled_env\fR method with a block\. Any subshells created inside the block will be given the environment present before Bundler was activated\. For example, Homebrew commands run Ruby, but don't work inside a bundle:
+.IP "" 4
+.nf
+Bundler\.with_unbundled_env do
+  `brew install wget`
+end
+.fi
+.IP "" 0
+.P
+Using \fBwith_unbundled_env\fR is also necessary if you are shelling out to a different bundle\. Any Bundler commands run in a subshell will inherit the current Gemfile, so commands that need to run in the context of a different bundle also need to use \fBwith_unbundled_env\fR\.
+.IP "" 4
+.nf
+Bundler\.with_unbundled_env do
+  Dir\.chdir "/other/bundler/project" do
+    `bundle exec \./script`
+  end
+end
+.fi
+.IP "" 0
+.P
+Bundler provides convenience helpers that wrap \fBsystem\fR and \fBexec\fR, and they can be used like this:
+.IP "" 4
+.nf
+Bundler\.unbundled_system('brew install wget')
+Bundler\.unbundled_exec('brew install wget')
+.fi
+.IP "" 0
+.SH "RUBYGEMS PLUGINS"
+At present, the Rubygems plugin system requires all files named \fBrubygems_plugin\.rb\fR on the load path of \fIany\fR installed gem when any Ruby code requires \fBrubygems\.rb\fR\. This includes executables installed into the system, like \fBrails\fR, \fBrackup\fR, and \fBrspec\fR\.
+.P
+Since Rubygems plugins can contain arbitrary Ruby code, they commonly end up activating themselves or their dependencies\.
+.P
+For instance, the \fBgemcutter 0\.5\fR gem depended on \fBjson_pure\fR\. If you had that version of gemcutter installed (even if you \fIalso\fR had a newer version without this problem), Rubygems would activate \fBgemcutter 0\.5\fR and \fBjson_pure <latest>\fR\.
+.P
+If your Gemfile(5) also contained \fBjson_pure\fR (or a gem with a dependency on \fBjson_pure\fR), the latest version on your system might conflict with the version in your Gemfile(5), or the snapshot version in your \fBGemfile\.lock\fR\.
+.P
+If this happens, bundler will say:
+.IP "" 4
+.nf
+You have already activated json_pure 1\.4\.6 but your Gemfile
+requires json_pure 1\.4\.3\. Consider using bundle exec\.
+.fi
+.IP "" 0
+.P
+In this situation, you almost certainly want to remove the underlying gem with the problematic gem plugin\. In general, the authors of these plugins (in this case, the \fBgemcutter\fR gem) have released newer versions that are more careful in their plugins\.
+.P
+You can find a list of all the gems containing gem plugins by running
+.IP "" 4
+.nf
+ruby \-e "puts Gem\.find_files('rubygems_plugin\.rb')"
+.fi
+.IP "" 0
+.P
+At the very least, you should remove all but the newest version of each gem plugin, and also remove all gem plugins that you aren't using (\fBgem uninstall gem_name\fR)\.
diff --git a/lib/bundler/man/bundle-exec.1.ronn b/lib/bundler/man/bundle-exec.1.ronn
new file mode 100644
index 0000000000..e51a66a084
--- /dev/null
+++ b/lib/bundler/man/bundle-exec.1.ronn
@@ -0,0 +1,150 @@
+bundle-exec(1) -- Execute a command in the context of the bundle
+================================================================
+
+## SYNOPSIS
+
+`bundle exec` [--gemfile=GEMFILE] <command>
+
+## DESCRIPTION
+
+This command executes the command, making all gems specified in the
+[`Gemfile(5)`][Gemfile(5)] available to `require` in Ruby programs.
+
+Essentially, if you would normally have run something like
+`rspec spec/my_spec.rb`, and you want to use the gems specified
+in the [`Gemfile(5)`][Gemfile(5)] and installed via [bundle install(1)](bundle-install.1.html), you
+should run `bundle exec rspec spec/my_spec.rb`.
+
+Note that `bundle exec` does not require that an executable is
+available on your shell's `$PATH`.
+
+## OPTIONS
+
+* `--gemfile=GEMFILE`:
+  Use the specified gemfile instead of [`Gemfile(5)`][Gemfile(5)].
+
+## BUNDLE INSTALL --BINSTUBS
+
+If you use the `--binstubs` flag in [bundle install(1)](bundle-install.1.html), Bundler will
+automatically create a directory (which defaults to `app_root/bin`)
+containing all of the executables available from gems in the bundle.
+
+After using `--binstubs`, `bin/rspec spec/my_spec.rb` is identical
+to `bundle exec rspec spec/my_spec.rb`.
+
+## ENVIRONMENT MODIFICATIONS
+
+`bundle exec` makes a number of changes to the shell environment,
+then executes the command you specify in full.
+
+* make sure that it's still possible to shell out to `bundle`
+  from inside a command invoked by `bundle exec` (using
+  `$BUNDLE_BIN_PATH`)
+* put the directory containing executables (like `rails`, `rspec`,
+  `rackup`) for your bundle on `$PATH`
+* make sure that if bundler is invoked in the subshell, it uses
+  the same `Gemfile` (by setting `BUNDLE_GEMFILE`)
+* add `-rbundler/setup` to `$RUBYOPT`, which makes sure that
+  Ruby programs invoked in the subshell can see the gems in
+  the bundle
+
+It also modifies Rubygems:
+
+* disallow loading additional gems not in the bundle
+* modify the `gem` method to be a no-op if a gem matching
+  the requirements is in the bundle, and to raise a
+  `Gem::LoadError` if it's not
+* Define `Gem.refresh` to be a no-op, since the source
+  index is always frozen when using bundler, and to
+  prevent gems from the system leaking into the environment
+* Override `Gem.bin_path` to use the gems in the bundle,
+  making system executables work
+* Add all gems in the bundle into Gem.loaded_specs
+
+Finally, `bundle exec` also implicitly modifies `Gemfile.lock` if the lockfile
+and the Gemfile do not match. Bundler needs the Gemfile to determine things
+such as a gem's groups, `autorequire`, and platforms, etc., and that
+information isn't stored in the lockfile. The Gemfile and lockfile must be
+synced in order to `bundle exec` successfully, so `bundle exec`
+updates the lockfile beforehand.
+
+### Loading
+
+By default, when attempting to `bundle exec` to a file with a ruby shebang,
+Bundler will `Kernel.load` that file instead of using `Kernel.exec`. For the
+vast majority of cases, this is a performance improvement. In a rare few cases,
+this could cause some subtle side-effects (such as dependence on the exact
+contents of `$0` or `__FILE__`) and the optimization can be disabled by enabling
+the `disable_exec_load` setting.
+
+### Shelling out
+
+Any Ruby code that opens a subshell (like `system`, backticks, or `%x{}`) will
+automatically use the current Bundler environment. If you need to shell out to
+a Ruby command that is not part of your current bundle, use the
+`with_unbundled_env` method with a block. Any subshells created inside the block
+will be given the environment present before Bundler was activated. For
+example, Homebrew commands run Ruby, but don't work inside a bundle:
+
+    Bundler.with_unbundled_env do
+      `brew install wget`
+    end
+
+Using `with_unbundled_env` is also necessary if you are shelling out to a different
+bundle. Any Bundler commands run in a subshell will inherit the current
+Gemfile, so commands that need to run in the context of a different bundle also
+need to use `with_unbundled_env`.
+
+    Bundler.with_unbundled_env do
+      Dir.chdir "/other/bundler/project" do
+        `bundle exec ./script`
+      end
+    end
+
+Bundler provides convenience helpers that wrap `system` and `exec`, and they
+can be used like this:
+
+    Bundler.unbundled_system('brew install wget')
+    Bundler.unbundled_exec('brew install wget')
+
+
+## RUBYGEMS PLUGINS
+
+At present, the Rubygems plugin system requires all files
+named `rubygems_plugin.rb` on the load path of _any_ installed
+gem when any Ruby code requires `rubygems.rb`. This includes
+executables installed into the system, like `rails`, `rackup`,
+and `rspec`.
+
+Since Rubygems plugins can contain arbitrary Ruby code, they
+commonly end up activating themselves or their dependencies.
+
+For instance, the `gemcutter 0.5` gem depended on `json_pure`.
+If you had that version of gemcutter installed (even if
+you _also_ had a newer version without this problem), Rubygems
+would activate `gemcutter 0.5` and `json_pure <latest>`.
+
+If your Gemfile(5) also contained `json_pure` (or a gem
+with a dependency on `json_pure`), the latest version on
+your system might conflict with the version in your
+Gemfile(5), or the snapshot version in your `Gemfile.lock`.
+
+If this happens, bundler will say:
+
+    You have already activated json_pure 1.4.6 but your Gemfile
+    requires json_pure 1.4.3. Consider using bundle exec.
+
+In this situation, you almost certainly want to remove the
+underlying gem with the problematic gem plugin. In general,
+the authors of these plugins (in this case, the `gemcutter`
+gem) have released newer versions that are more careful in
+their plugins.
+
+You can find a list of all the gems containing gem plugins
+by running
+
+    ruby -e "puts Gem.find_files('rubygems_plugin.rb')"
+
+At the very least, you should remove all but the newest
+version of each gem plugin, and also remove all gem plugins
+that you aren't using (`gem uninstall gem_name`).
diff --git a/lib/bundler/man/bundle-fund.1 b/lib/bundler/man/bundle-fund.1
new file mode 100644
index 0000000000..caee1f81dd
--- /dev/null
+++ b/lib/bundler/man/bundle-fund.1
@@ -0,0 +1,22 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-FUND" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-fund\fR \- Lists information about gems seeking funding assistance
+.SH "SYNOPSIS"
+\fBbundle fund\fR [\fIOPTIONS\fR]
+.SH "DESCRIPTION"
+\fBbundle fund\fR lists information about gems seeking funding assistance\.
+.SH "OPTIONS"
+.TP
+\fB\-\-group=<list>\fR, \fB\-g=<list>\fR
+Fetch funding information for a specific group\.
+.SH "EXAMPLES"
+.nf
+# Lists funding information for all gems
+bundle fund
+
+# Lists funding information for a specific group
+bundle fund \-\-group=security
+.fi
+
diff --git a/lib/bundler/man/bundle-fund.1.ronn b/lib/bundler/man/bundle-fund.1.ronn
new file mode 100644
index 0000000000..faf8b9c4a7
--- /dev/null
+++ b/lib/bundler/man/bundle-fund.1.ronn
@@ -0,0 +1,25 @@
+bundle-fund(1) -- Lists information about gems seeking funding assistance
+=========================================================================
+
+## SYNOPSIS
+
+`bundle fund` [*OPTIONS*]
+
+## DESCRIPTION
+
+**bundle fund** lists information about gems seeking funding assistance.
+
+## OPTIONS
+
+* `--group=<list>`, `-g=<list>`:
+  Fetch funding information for a specific group.
+
+## EXAMPLES
+
+```
+# Lists funding information for all gems
+bundle fund
+
+# Lists funding information for a specific group
+bundle fund --group=security
+```
diff --git a/lib/bundler/man/bundle-gem.1 b/lib/bundler/man/bundle-gem.1
new file mode 100644
index 0000000000..87d7568246
--- /dev/null
+++ b/lib/bundler/man/bundle-gem.1
@@ -0,0 +1,107 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-GEM" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-gem\fR \- Generate a project skeleton for creating a rubygem
+.SH "SYNOPSIS"
+\fBbundle gem\fR \fIGEM_NAME\fR \fIOPTIONS\fR
+.SH "DESCRIPTION"
+Generates a directory named \fBGEM_NAME\fR with a \fBRakefile\fR, \fBGEM_NAME\.gemspec\fR, and other supporting files and directories that can be used to develop a rubygem with that name\.
+.P
+Run \fBrake \-T\fR in the resulting project for a list of Rake tasks that can be used to test and publish the gem to rubygems\.org\.
+.P
+The generated project skeleton can be customized with OPTIONS, as explained below\. Note that these options can also be specified via Bundler's global configuration file using the following names:
+.IP "\(bu" 4
+\fBgem\.coc\fR
+.IP "\(bu" 4
+\fBgem\.mit\fR
+.IP "\(bu" 4
+\fBgem\.test\fR
+.IP "" 0
+.SH "OPTIONS"
+.TP
+\fB\-\-exe\fR, \fB\-\-bin\fR, \fB\-b\fR
+Specify that Bundler should create a binary executable (as \fBexe/GEM_NAME\fR) in the generated rubygem project\. This binary will also be added to the \fBGEM_NAME\.gemspec\fR manifest\. This behavior is disabled by default\.
+.TP
+\fB\-\-no\-exe\fR
+Do not create a binary (overrides \fB\-\-exe\fR specified in the global config)\.
+.TP
+\fB\-\-coc\fR
+Add a \fBCODE_OF_CONDUCT\.md\fR file to the root of the generated project\. If this option is unspecified, an interactive prompt will be displayed and the answer will be saved in Bundler's global config for future \fBbundle gem\fR use\.
+.TP
+\fB\-\-no\-coc\fR
+Do not create a \fBCODE_OF_CONDUCT\.md\fR (overrides \fB\-\-coc\fR specified in the global config)\.
+.TP
+\fB\-\-changelog\fR
+Add a \fBCHANGELOG\.md\fR file to the root of the generated project\. If this option is unspecified, an interactive prompt will be displayed and the answer will be saved in Bundler's global config for future \fBbundle gem\fR use\. Update the default with \fBbundle config set \-\-global gem\.changelog <true|false>\fR\.
+.TP
+\fB\-\-no\-changelog\fR
+Do not create a \fBCHANGELOG\.md\fR (overrides \fB\-\-changelog\fR specified in the global config)\.
+.TP
+\fB\-\-ext=c\fR, \fB\-\-ext=go\fR, \fB\-\-ext=rust\fR
+Add boilerplate for C, Go (currently go\-gem\-wrapper \fIhttps://github\.com/ruby\-go\-gem/go\-gem\-wrapper\fR based) or Rust (currently magnus \fIhttps://docs\.rs/magnus\fR based) extension code to the generated project\. This behavior is disabled by default\.
+.TP
+\fB\-\-no\-ext\fR
+Do not add extension code (overrides \fB\-\-ext\fR specified in the global config)\.
+.TP
+\fB\-\-git\fR
+Initialize a git repo inside your library\.
+.TP
+\fB\-\-github\-username=GITHUB_USERNAME\fR
+Fill in GitHub username on README so that you don't have to do it manually\. Set a default with \fBbundle config set \-\-global gem\.github_username <your_username>\fR\.
+.TP
+\fB\-\-mit\fR
+Add an MIT license to a \fBLICENSE\.txt\fR file in the root of the generated project\. Your name from the global git config is used for the copyright statement\. If this option is unspecified, an interactive prompt will be displayed and the answer will be saved in Bundler's global config for future \fBbundle gem\fR use\.
+.TP
+\fB\-\-no\-mit\fR
+Do not create a \fBLICENSE\.txt\fR (overrides \fB\-\-mit\fR specified in the global config)\.
+.TP
+\fB\-t\fR, \fB\-\-test=minitest\fR, \fB\-\-test=rspec\fR, \fB\-\-test=test\-unit\fR
+Specify the test framework that Bundler should use when generating the project\. Acceptable values are \fBminitest\fR, \fBrspec\fR and \fBtest\-unit\fR\. The \fBGEM_NAME\.gemspec\fR will be configured and a skeleton test/spec directory will be created based on this option\. Given no option is specified:
+.IP
+When Bundler is configured to generate tests, this defaults to Bundler's global config setting \fBgem\.test\fR\.
+.IP
+When Bundler is configured to not generate tests, an interactive prompt will be displayed and the answer will be used for the current rubygem project\.
+.IP
+When Bundler is unconfigured, an interactive prompt will be displayed and the answer will be saved in Bundler's global config for future \fBbundle gem\fR use\.
+.TP
+\fB\-\-no\-test\fR
+Do not use a test framework (overrides \fB\-\-test\fR specified in the global config)\.
+.TP
+\fB\-\-ci\fR, \fB\-\-ci=circle\fR, \fB\-\-ci=github\fR, \fB\-\-ci=gitlab\fR
+Specify the continuous integration service that Bundler should use when generating the project\. Acceptable values are \fBgithub\fR, \fBgitlab\fR and \fBcircle\fR\. A configuration file will be generated in the project directory\. Given no option is specified:
+.IP
+When Bundler is configured to generate CI files, this defaults to Bundler's global config setting \fBgem\.ci\fR\.
+.IP
+When Bundler is configured to not generate CI files, an interactive prompt will be displayed and the answer will be used for the current rubygem project\.
+.IP
+When Bundler is unconfigured, an interactive prompt will be displayed and the answer will be saved in Bundler's global config for future \fBbundle gem\fR use\.
+.TP
+\fB\-\-no\-ci\fR
+Do not use a continuous integration service (overrides \fB\-\-ci\fR specified in the global config)\.
+.TP
+\fB\-\-linter\fR, \fB\-\-linter=rubocop\fR, \fB\-\-linter=standard\fR
+Specify the linter and code formatter that Bundler should add to the project's development dependencies\. Acceptable values are \fBrubocop\fR and \fBstandard\fR\. A configuration file will be generated in the project directory\. Given no option is specified:
+.IP
+When Bundler is configured to add a linter, this defaults to Bundler's global config setting \fBgem\.linter\fR\.
+.IP
+When Bundler is configured not to add a linter, an interactive prompt will be displayed and the answer will be used for the current rubygem project\.
+.IP
+When Bundler is unconfigured, an interactive prompt will be displayed and the answer will be saved in Bundler's global config for future \fBbundle gem\fR use\.
+.TP
+\fB\-\-no\-linter\fR
+Do not add a linter (overrides \fB\-\-linter\fR specified in the global config)\.
+.TP
+\fB\-\-edit=EDIT\fR, \fB\-e=EDIT\fR
+Open the resulting GEM_NAME\.gemspec in EDIT, or the default editor if not specified\. The default is \fB$BUNDLER_EDITOR\fR, \fB$VISUAL\fR, or \fB$EDITOR\fR\.
+.TP
+\fB\-\-bundle\fR
+Run \fBbundle install\fR after creating the gem\.
+.TP
+\fB\-\-no\-bundle\fR
+Do not run \fBbundle install\fR after creating the gem\.
+.SH "SEE ALSO"
+.IP "\(bu" 4
+bundle config(1) \fIbundle\-config\.1\.html\fR
+.IP "" 0
+
diff --git a/lib/bundler/man/bundle-gem.1.ronn b/lib/bundler/man/bundle-gem.1.ronn
new file mode 100644
index 0000000000..488c8113e4
--- /dev/null
+++ b/lib/bundler/man/bundle-gem.1.ronn
@@ -0,0 +1,150 @@
+bundle-gem(1) -- Generate a project skeleton for creating a rubygem
+===================================================================
+
+## SYNOPSIS
+
+`bundle gem` <GEM_NAME> [OPTIONS]
+
+## DESCRIPTION
+
+Generates a directory named `GEM_NAME` with a `Rakefile`, `GEM_NAME.gemspec`,
+and other supporting files and directories that can be used to develop a
+rubygem with that name.
+
+Run `rake -T` in the resulting project for a list of Rake tasks that can be used
+to test and publish the gem to rubygems.org.
+
+The generated project skeleton can be customized with OPTIONS, as explained
+below. Note that these options can also be specified via Bundler's global
+configuration file using the following names:
+
+* `gem.coc`
+* `gem.mit`
+* `gem.test`
+
+## OPTIONS
+
+* `--exe`, `--bin`, `-b`:
+  Specify that Bundler should create a binary executable (as `exe/GEM_NAME`)
+  in the generated rubygem project. This binary will also be added to the
+  `GEM_NAME.gemspec` manifest. This behavior is disabled by default.
+
+* `--no-exe`:
+  Do not create a binary (overrides `--exe` specified in the global config).
+
+* `--coc`:
+  Add a `CODE_OF_CONDUCT.md` file to the root of the generated project. If
+  this option is unspecified, an interactive prompt will be displayed and the
+  answer will be saved in Bundler's global config for future `bundle gem` use.
+
+* `--no-coc`:
+  Do not create a `CODE_OF_CONDUCT.md` (overrides `--coc` specified in the
+  global config).
+
+* `--changelog`:
+  Add a `CHANGELOG.md` file to the root of the generated project. If
+  this option is unspecified, an interactive prompt will be displayed and the
+  answer will be saved in Bundler's global config for future `bundle gem` use.
+  Update the default with `bundle config set --global gem.changelog <true|false>`.
+
+* `--no-changelog`:
+  Do not create a `CHANGELOG.md` (overrides `--changelog` specified in the
+  global config).
+
+* `--ext=c`, `--ext=go`, `--ext=rust`:
+  Add boilerplate for C, Go (currently [go-gem-wrapper](https://github.com/ruby-go-gem/go-gem-wrapper) based) or Rust (currently [magnus](https://docs.rs/magnus) based) extension code to the generated project. This behavior
+  is disabled by default.
+
+* `--no-ext`:
+  Do not add extension code (overrides `--ext` specified in the global
+  config).
+
+* `--git`:
+  Initialize a git repo inside your library.
+
+* `--github-username=GITHUB_USERNAME`:
+  Fill in GitHub username on README so that you don't have to do it manually. Set a default with `bundle config set --global gem.github_username <your_username>`.
+
+* `--mit`:
+  Add an MIT license to a `LICENSE.txt` file in the root of the generated
+  project. Your name from the global git config is used for the copyright
+  statement. If this option is unspecified, an interactive prompt will be
+  displayed and the answer will be saved in Bundler's global config for future
+  `bundle gem` use.
+
+* `--no-mit`:
+  Do not create a `LICENSE.txt` (overrides `--mit` specified in the global
+  config).
+
+* `-t`, `--test=minitest`, `--test=rspec`, `--test=test-unit`:
+  Specify the test framework that Bundler should use when generating the
+  project. Acceptable values are `minitest`, `rspec` and `test-unit`. The
+  `GEM_NAME.gemspec` will be configured and a skeleton test/spec directory will
+  be created based on this option. Given no option is specified:
+
+  When Bundler is configured to generate tests, this defaults to Bundler's
+  global config setting `gem.test`.
+
+  When Bundler is configured to not generate tests, an interactive prompt will
+  be displayed and the answer will be used for the current rubygem project.
+
+  When Bundler is unconfigured, an interactive prompt will be displayed and
+  the answer will be saved in Bundler's global config for future `bundle gem`
+  use.
+
+* `--no-test`:
+  Do not use a test framework (overrides `--test` specified in the global
+  config).
+
+* `--ci`, `--ci=circle`, `--ci=github`, `--ci=gitlab`:
+  Specify the continuous integration service that Bundler should use when
+  generating the project. Acceptable values are `github`, `gitlab`
+  and `circle`. A configuration file will be generated in the project directory.
+  Given no option is specified:
+
+  When Bundler is configured to generate CI files, this defaults to Bundler's
+  global config setting `gem.ci`.
+
+  When Bundler is configured to not generate CI files, an interactive prompt
+  will be displayed and the answer will be used for the current rubygem project.
+
+  When Bundler is unconfigured, an interactive prompt will be displayed and
+  the answer will be saved in Bundler's global config for future `bundle gem`
+  use.
+
+* `--no-ci`:
+  Do not use a continuous integration service (overrides `--ci` specified in
+  the global config).
+
+* `--linter`, `--linter=rubocop`, `--linter=standard`:
+  Specify the linter and code formatter that Bundler should add to the
+  project's development dependencies. Acceptable values are `rubocop` and
+  `standard`. A configuration file will be generated in the project directory.
+  Given no option is specified:
+
+  When Bundler is configured to add a linter, this defaults to Bundler's
+  global config setting `gem.linter`.
+
+  When Bundler is configured not to add a linter, an interactive prompt
+  will be displayed and the answer will be used for the current rubygem project.
+
+  When Bundler is unconfigured, an interactive prompt will be displayed and
+  the answer will be saved in Bundler's global config for future `bundle gem`
+  use.
+
+* `--no-linter`:
+  Do not add a linter (overrides `--linter` specified in the global config).
+
+* `--edit=EDIT`, `-e=EDIT`:
+  Open the resulting GEM_NAME.gemspec in EDIT, or the default editor if not
+  specified. The default is `$BUNDLER_EDITOR`, `$VISUAL`, or `$EDITOR`.
+
+* `--bundle`:
+  Run `bundle install` after creating the gem.
+
+* `--no-bundle`:
+  Do not run `bundle install` after creating the gem.
+
+## SEE ALSO
+
+* [bundle config(1)](bundle-config.1.html)
diff --git a/lib/bundler/man/bundle-help.1 b/lib/bundler/man/bundle-help.1
new file mode 100644
index 0000000000..3bcfd047e5
--- /dev/null
+++ b/lib/bundler/man/bundle-help.1
@@ -0,0 +1,9 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-HELP" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-help\fR \- Displays detailed help for each subcommand
+.SH "SYNOPSIS"
+\fBbundle help\fR [COMMAND]
+.SH "DESCRIPTION"
+Displays detailed help for the given subcommand\. You can specify a single \fBCOMMAND\fR at the same time\. When \fBCOMMAND\fR is omitted, help for \fBhelp\fR command will be displayed\.
diff --git a/lib/bundler/man/bundle-help.1.ronn b/lib/bundler/man/bundle-help.1.ronn
new file mode 100644
index 0000000000..0e144aead7
--- /dev/null
+++ b/lib/bundler/man/bundle-help.1.ronn
@@ -0,0 +1,12 @@
+bundle-help(1) -- Displays detailed help for each subcommand
+============================================================
+
+## SYNOPSIS
+
+`bundle help` [COMMAND]
+
+## DESCRIPTION
+
+Displays detailed help for the given subcommand.
+You can specify a single `COMMAND` at the same time.
+When `COMMAND` is omitted, help for `help` command will be displayed.
diff --git a/lib/bundler/man/bundle-info.1 b/lib/bundler/man/bundle-info.1
new file mode 100644
index 0000000000..49c2295f8c
--- /dev/null
+++ b/lib/bundler/man/bundle-info.1
@@ -0,0 +1,17 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-INFO" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-info\fR \- Show information for the given gem in your bundle
+.SH "SYNOPSIS"
+\fBbundle info\fR [GEM_NAME] [\-\-path] [\-\-version]
+.SH "DESCRIPTION"
+Given a gem name present in your bundle, print the basic information about it such as homepage, version, path and summary\.
+.SH "OPTIONS"
+.TP
+\fB\-\-path\fR
+Print the path of the given gem
+.TP
+\fB\-\-version\fR
+Print gem version
+
diff --git a/lib/bundler/man/bundle-info.1.ronn b/lib/bundler/man/bundle-info.1.ronn
new file mode 100644
index 0000000000..e99db8c614
--- /dev/null
+++ b/lib/bundler/man/bundle-info.1.ronn
@@ -0,0 +1,21 @@
+bundle-info(1) -- Show information for the given gem in your bundle
+===================================================================
+
+## SYNOPSIS
+
+`bundle info` [GEM_NAME]
+              [--path]
+              [--version]
+
+## DESCRIPTION
+
+Given a gem name present in your bundle, print the basic information about it
+ such as homepage, version, path and summary.
+
+## OPTIONS
+
+* `--path`:
+  Print the path of the given gem
+
+* `--version`:
+  Print gem version
diff --git a/lib/bundler/man/bundle-init.1 b/lib/bundler/man/bundle-init.1
new file mode 100644
index 0000000000..63e2376c3f
--- /dev/null
+++ b/lib/bundler/man/bundle-init.1
@@ -0,0 +1,20 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-INIT" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-init\fR \- Generates a Gemfile into the current working directory
+.SH "SYNOPSIS"
+\fBbundle init\fR [\-\-gemspec=FILE]
+.SH "DESCRIPTION"
+Init generates a default [\fBGemfile(5)\fR][Gemfile(5)] in the current working directory\. When adding a [\fBGemfile(5)\fR][Gemfile(5)] to a gem with a gemspec, the \fB\-\-gemspec\fR option will automatically add each dependency listed in the gemspec file to the newly created [\fBGemfile(5)\fR][Gemfile(5)]\.
+.SH "OPTIONS"
+.TP
+\fB\-\-gemspec=GEMSPEC\fR
+Use the specified \.gemspec to create the [\fBGemfile(5)\fR][Gemfile(5)]
+.TP
+\fB\-\-gemfile=GEMFILE\fR
+Use the specified name for the gemfile instead of \fBGemfile\fR
+.SH "FILES"
+Included in the default [\fBGemfile(5)\fR][Gemfile(5)] generated is the line \fB# frozen_string_literal: true\fR\. This is a magic comment supported for the first time in Ruby 2\.3\. The presence of this line results in all string literals in the file being implicitly frozen\.
+.SH "SEE ALSO"
+Gemfile(5) \fIhttps://bundler\.io/man/gemfile\.5\.html\fR
diff --git a/lib/bundler/man/bundle-init.1.ronn b/lib/bundler/man/bundle-init.1.ronn
new file mode 100644
index 0000000000..ab3c427b52
--- /dev/null
+++ b/lib/bundler/man/bundle-init.1.ronn
@@ -0,0 +1,32 @@
+bundle-init(1) -- Generates a Gemfile into the current working directory
+========================================================================
+
+## SYNOPSIS
+
+`bundle init` [--gemspec=FILE]
+
+## DESCRIPTION
+
+Init generates a default [`Gemfile(5)`][Gemfile(5)] in the current working directory. When
+adding a [`Gemfile(5)`][Gemfile(5)] to a gem with a gemspec, the `--gemspec` option will
+automatically add each dependency listed in the gemspec file to the newly
+created [`Gemfile(5)`][Gemfile(5)].
+
+## OPTIONS
+
+* `--gemspec=GEMSPEC`:
+  Use the specified .gemspec to create the [`Gemfile(5)`][Gemfile(5)]
+
+* `--gemfile=GEMFILE`:
+  Use the specified name for the gemfile instead of `Gemfile`
+
+## FILES
+
+Included in the default [`Gemfile(5)`][Gemfile(5)]
+generated is the line `# frozen_string_literal: true`. This is a magic comment
+supported for the first time in Ruby 2.3. The presence of this line
+results in all string literals in the file being implicitly frozen.
+
+## SEE ALSO
+
+[Gemfile(5)](https://bundler.io/man/gemfile.5.html)
diff --git a/lib/bundler/man/bundle-install.1 b/lib/bundler/man/bundle-install.1
new file mode 100644
index 0000000000..801768c7ec
--- /dev/null
+++ b/lib/bundler/man/bundle-install.1
@@ -0,0 +1,178 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-INSTALL" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-install\fR \- Install the dependencies specified in your Gemfile
+.SH "SYNOPSIS"
+\fBbundle install\fR [\-\-cooldown=NUMBER] [\-\-force] [\-\-full\-index] [\-\-gemfile=GEMFILE] [\-\-jobs=NUMBER] [\-\-local] [\-\-lockfile=LOCKFILE] [\-\-no\-cache] [\-\-no\-lock] [\-\-prefer\-local] [\-\-quiet] [\-\-retry=NUMBER] [\-\-standalone[=GROUP[ GROUP\|\.\|\.\|\.]]] [\-\-trust\-policy=TRUST\-POLICY] [\-\-target\-rbconfig=TARGET\-RBCONFIG]
+.SH "DESCRIPTION"
+Install the gems specified in your Gemfile(5)\. If this is the first time you run bundle install (and a \fBGemfile\.lock\fR does not exist), Bundler will fetch all remote sources, resolve dependencies and install all needed gems\.
+.P
+If a \fBGemfile\.lock\fR does exist, and you have not updated your Gemfile(5), Bundler will fetch all remote sources, but use the dependencies specified in the \fBGemfile\.lock\fR instead of resolving dependencies\.
+.P
+If a \fBGemfile\.lock\fR does exist, and you have updated your Gemfile(5), Bundler will use the dependencies in the \fBGemfile\.lock\fR for all gems that you did not update, but will re\-resolve the dependencies of gems that you did update\. You can find more information about this update process below under \fICONSERVATIVE UPDATING\fR\.
+.SH "OPTIONS"
+.TP
+\fB\-\-cooldown=<number>\fR
+Only consider gem versions published at least \fInumber\fR days ago when resolving\. Pass \fB0\fR to disable cooldown for this run, overriding any per\-source or global configuration\. See \fBcooldown\fR in bundle\-config(1) for details on the precedence between the CLI flag, Bundler config, and Gemfile per\-source settings\.
+.TP
+\fB\-\-force\fR, \fB\-\-redownload\fR
+Force reinstalling every gem, even if already installed\.
+.TP
+\fB\-\-full\-index\fR
+Bundler will not call Rubygems' API endpoint (default) but download and cache a (currently big) index file of all gems\. Performance can be improved for large bundles that seldom change by enabling this option\.
+.TP
+\fB\-\-gemfile=GEMFILE\fR
+The location of the Gemfile(5) which Bundler should use\. This defaults to a Gemfile(5) in the current working directory\. In general, Bundler will assume that the location of the Gemfile(5) is also the project's root and will try to find \fBGemfile\.lock\fR and \fBvendor/cache\fR relative to this location\.
+.TP
+\fB\-\-jobs=<number>\fR, \fB\-j=<number>\fR
+The maximum number of parallel download and install jobs\. The default is the number of available processors\.
+.TP
+\fB\-\-local\fR
+Do not attempt to connect to \fBrubygems\.org\fR\. Instead, Bundler will use the gems already present in Rubygems' cache or in \fBvendor/cache\fR\. Note that if an appropriate platform\-specific gem exists on \fBrubygems\.org\fR it will not be found\.
+.TP
+\fB\-\-lockfile=LOCKFILE\fR
+The location of the lockfile which Bundler should use\. This defaults to the Gemfile location with \fB\.lock\fR appended\.
+.TP
+\fB\-\-prefer\-local\fR
+Force using locally installed gems, or gems already present in Rubygems' cache or in \fBvendor/cache\fR, when resolving, even if newer versions are available remotely\. Only attempt to connect to \fBrubygems\.org\fR for gems that are not present locally\.
+.TP
+\fB\-\-no\-cache\fR
+Do not update the cache in \fBvendor/cache\fR with the newly bundled gems\. This does not remove any gems in the cache but keeps the newly bundled gems from being cached during the install\.
+.TP
+\fB\-\-no\-lock\fR
+Do not create a lockfile\. Useful if you want to install dependencies but not lock versions of gems\. Recommended for library development, and other situations where the code is expected to work with a range of dependency versions\.
+.IP
+This has the same effect as using \fBlockfile false\fR in the Gemfile\. See gemfile(5) for more information\.
+.TP
+\fB\-\-quiet\fR
+Do not print progress information to the standard output\.
+.TP
+\fB\-\-retry=[<number>]\fR
+Retry failed network or git requests for \fInumber\fR times\.
+.TP
+\fB\-\-standalone[=<list>]\fR
+Makes a bundle that can work without depending on Rubygems or Bundler at runtime\. A space separated list of groups to install can be specified\. Bundler creates a directory named \fBbundle\fR and installs the bundle there\. It also generates a \fBbundle/bundler/setup\.rb\fR file to replace Bundler's own setup in the manner required\.
+.TP
+\fB\-\-trust\-policy=TRUST\-POLICY\fR
+Apply the Rubygems security policy \fIpolicy\fR, where policy is one of \fBHighSecurity\fR, \fBMediumSecurity\fR, \fBLowSecurity\fR, \fBAlmostNoSecurity\fR, or \fBNoSecurity\fR\. For more details, please see the Rubygems signing documentation linked below in \fISEE ALSO\fR\.
+.TP
+\fB\-\-target\-rbconfig=TARGET\-RBCONFIG\fR
+Path to rbconfig\.rb for the deployment target platform\.
+.SH "DEPLOYMENT MODE"
+Bundler's defaults are optimized for development\. To switch to defaults optimized for deployment and for CI, use the \fBdeployment\fR setting\. Do not activate deployment mode on development machines, as it will cause an error when the Gemfile(5) is modified\.
+.IP "1." 4
+A \fBGemfile\.lock\fR is required\.
+.IP
+To ensure that the same versions of the gems you developed with and tested with are also used in deployments, a \fBGemfile\.lock\fR is required\.
+.IP
+This is mainly to ensure that you remember to check your \fBGemfile\.lock\fR into version control\.
+.IP "2." 4
+The \fBGemfile\.lock\fR must be up to date
+.IP
+In development, you can modify your Gemfile(5) and re\-run \fBbundle install\fR to \fIconservatively update\fR your \fBGemfile\.lock\fR snapshot\.
+.IP
+In deployment, your \fBGemfile\.lock\fR should be up\-to\-date with changes made in your Gemfile(5)\.
+.IP "3." 4
+Gems are installed to \fBvendor/bundle\fR not your default system location
+.IP
+In development, it's convenient to share the gems used in your application with other applications and other scripts that run on the system\.
+.IP
+In deployment, isolation is a more important default\. In addition, the user deploying the application may not have permission to install gems to the system, or the web server may not have permission to read them\.
+.IP
+As a result, when \fBdeployment\fR is configured, \fBbundle install\fR installs gems to the \fBvendor/bundle\fR directory in the application\. This may be overridden using the \fBpath\fR setting\.
+.IP "" 0
+.SH "INSTALLING GROUPS"
+By default, \fBbundle install\fR will install all gems in all groups in your Gemfile(5), except those declared for a different platform\.
+.P
+However, you can explicitly tell Bundler to skip installing certain groups with the \fBwithout\fR setting\. This setting takes a space\-separated list of groups\.
+.P
+While the \fBwithout\fR setting will skip \fIinstalling\fR the gems in the specified groups, \fBbundle install\fR will still \fIdownload\fR those gems and use them to resolve the dependencies of every gem in your Gemfile(5)\.
+.P
+This is so that installing a different set of groups on another machine (such as a production server) will not change the gems and versions that you have already developed and tested against\.
+.P
+\fBBundler offers a rock\-solid guarantee that the third\-party code you are running in development and testing is also the third\-party code you are running in production\. You can choose to exclude some of that code in different environments, but you will never be caught flat\-footed by different versions of third\-party code being used in different environments\.\fR
+.P
+For a simple illustration, consider the following Gemfile(5):
+.IP "" 4
+.nf
+source 'https://rubygems\.org'
+
+gem 'sinatra'
+
+group :production do
+  gem 'rack\-perftools\-profiler'
+end
+.fi
+.IP "" 0
+.P
+In this case, \fBsinatra\fR depends on any version of Rack (\fB>= 1\.0\fR), while \fBrack\-perftools\-profiler\fR depends on 1\.x (\fB~> 1\.0\fR)\.
+.P
+When you configure \fBbundle config without production\fR in development, we look at the dependencies of \fBrack\-perftools\-profiler\fR as well\. That way, you do not spend all your time developing against Rack 2\.0, using new APIs unavailable in Rack 1\.x, only to have Bundler switch to Rack 1\.2 when the \fBproduction\fR group \fIis\fR used\.
+.P
+This should not cause any problems in practice, because we do not attempt to \fBinstall\fR the gems in the excluded groups, and only evaluate as part of the dependency resolution process\.
+.P
+This also means that you cannot include different versions of the same gem in different groups, because doing so would result in different sets of dependencies used in development and production\. Because of the vagaries of the dependency resolution process, this usually affects more than the gems you list in your Gemfile(5), and can (surprisingly) radically change the gems you are using\.
+.SH "THE GEMFILE\.LOCK"
+When you run \fBbundle install\fR, Bundler will persist the full names and versions of all gems that you used (including dependencies of the gems specified in the Gemfile(5)) into a file called \fBGemfile\.lock\fR\.
+.P
+Bundler uses this file in all subsequent calls to \fBbundle install\fR, which guarantees that you always use the same exact code, even as your application moves across machines\.
+.P
+Because of the way dependency resolution works, even a seemingly small change (for instance, an update to a point\-release of a dependency of a gem in your Gemfile(5)) can result in radically different gems being needed to satisfy all dependencies\.
+.P
+As a result, you \fBSHOULD\fR check your \fBGemfile\.lock\fR into version control, in both applications and gems\. If you do not, every machine that checks out your repository (including your production server) will resolve all dependencies again, which will result in different versions of third\-party code being used if \fBany\fR of the gems in the Gemfile(5) or any of their dependencies have been updated\.
+.P
+When Bundler first shipped, the \fBGemfile\.lock\fR was included in the \fB\.gitignore\fR file included with generated gems\. Over time, however, it became clear that this practice forces the pain of broken dependencies onto new contributors, while leaving existing contributors potentially unaware of the problem\. Since \fBbundle install\fR is usually the first step towards a contribution, the pain of broken dependencies would discourage new contributors from contributing\. As a result, we have revised our guidance for gem authors to now recommend checking in the lock for gems\.
+.SH "CONSERVATIVE UPDATING"
+When you make a change to the Gemfile(5) and then run \fBbundle install\fR, Bundler will update only the gems that you modified\.
+.P
+In other words, if a gem that you \fBdid not modify\fR worked before you called \fBbundle install\fR, it will continue to use the exact same versions of all dependencies as it used before the update\.
+.P
+Let's take a look at an example\. Here's your original Gemfile(5):
+.IP "" 4
+.nf
+source 'https://rubygems\.org'
+
+gem 'actionpack', '2\.3\.8'
+gem 'activemerchant'
+.fi
+.IP "" 0
+.P
+In this case, both \fBactionpack\fR and \fBactivemerchant\fR depend on \fBactivesupport\fR\. The \fBactionpack\fR gem depends on \fBactivesupport 2\.3\.8\fR and \fBrack ~> 1\.1\.0\fR, while the \fBactivemerchant\fR gem depends on \fBactivesupport >= 2\.3\.2\fR, \fBbraintree >= 2\.0\.0\fR, and \fBbuilder >= 2\.0\.0\fR\.
+.P
+When the dependencies are first resolved, Bundler will select \fBactivesupport 2\.3\.8\fR, which satisfies the requirements of both gems in your Gemfile(5)\.
+.P
+Next, you modify your Gemfile(5) to:
+.IP "" 4
+.nf
+source 'https://rubygems\.org'
+
+gem 'actionpack', '3\.0\.0\.rc'
+gem 'activemerchant'
+.fi
+.IP "" 0
+.P
+The \fBactionpack 3\.0\.0\.rc\fR gem has a number of new dependencies, and updates the \fBactivesupport\fR dependency to \fB= 3\.0\.0\.rc\fR and the \fBrack\fR dependency to \fB~> 1\.2\.1\fR\.
+.P
+When you run \fBbundle install\fR, Bundler notices that you changed the \fBactionpack\fR gem, but not the \fBactivemerchant\fR gem\. It evaluates the gems currently being used to satisfy its requirements:
+.TP
+\fBactivesupport 2\.3\.8\fR
+also used to satisfy a dependency in \fBactivemerchant\fR, which is not being updated
+.TP
+\fBrack ~> 1\.1\.0\fR
+not currently being used to satisfy another dependency
+.P
+Because you did not explicitly ask to update \fBactivemerchant\fR, you would not expect it to suddenly stop working after updating \fBactionpack\fR\. However, satisfying the new \fBactivesupport 3\.0\.0\.rc\fR dependency of actionpack requires updating one of its dependencies\.
+.P
+Even though \fBactivemerchant\fR declares a very loose dependency that theoretically matches \fBactivesupport 3\.0\.0\.rc\fR, Bundler treats gems in your Gemfile(5) that have not changed as an atomic unit together with their dependencies\. In this case, the \fBactivemerchant\fR dependency is treated as \fBactivemerchant 1\.7\.1 + activesupport 2\.3\.8\fR, so \fBbundle install\fR will report that it cannot update \fBactionpack\fR\.
+.P
+To explicitly update \fBactionpack\fR, including its dependencies which other gems in the Gemfile(5) still depend on, run \fBbundle update actionpack\fR (see \fBbundle update(1)\fR)\.
+.P
+\fBSummary\fR: In general, after making a change to the Gemfile(5) , you should first try to run \fBbundle install\fR, which will guarantee that no other gem in the Gemfile(5) is impacted by the change\. If that does not work, run bundle update(1) \fIbundle\-update\.1\.html\fR\.
+.SH "SEE ALSO"
+.IP "\(bu" 4
+Gem install docs \fIhttps://guides\.rubygems\.org/rubygems\-basics/#installing\-gems\fR
+.IP "\(bu" 4
+Rubygems signing docs \fIhttps://guides\.rubygems\.org/security/\fR
+.IP "" 0
+
diff --git a/lib/bundler/man/bundle-install.1.ronn b/lib/bundler/man/bundle-install.1.ronn
new file mode 100644
index 0000000000..56fd8bdf42
--- /dev/null
+++ b/lib/bundler/man/bundle-install.1.ronn
@@ -0,0 +1,314 @@
+bundle-install(1) -- Install the dependencies specified in your Gemfile
+=======================================================================
+
+## SYNOPSIS
+
+`bundle install` [--cooldown=NUMBER]
+                 [--force]
+                 [--full-index]
+                 [--gemfile=GEMFILE]
+                 [--jobs=NUMBER]
+                 [--local]
+                 [--lockfile=LOCKFILE]
+                 [--no-cache]
+                 [--no-lock]
+                 [--prefer-local]
+                 [--quiet]
+                 [--retry=NUMBER]
+                 [--standalone[=GROUP[ GROUP...]]]
+                 [--trust-policy=TRUST-POLICY]
+                 [--target-rbconfig=TARGET-RBCONFIG]
+
+## DESCRIPTION
+
+Install the gems specified in your Gemfile(5). If this is the first
+time you run bundle install (and a `Gemfile.lock` does not exist),
+Bundler will fetch all remote sources, resolve dependencies and
+install all needed gems.
+
+If a `Gemfile.lock` does exist, and you have not updated your Gemfile(5),
+Bundler will fetch all remote sources, but use the dependencies
+specified in the `Gemfile.lock` instead of resolving dependencies.
+
+If a `Gemfile.lock` does exist, and you have updated your Gemfile(5),
+Bundler will use the dependencies in the `Gemfile.lock` for all gems
+that you did not update, but will re-resolve the dependencies of
+gems that you did update. You can find more information about this
+update process below under [CONSERVATIVE UPDATING][].
+
+## OPTIONS
+
+* `--cooldown=<number>`:
+  Only consider gem versions published at least <number> days ago when
+  resolving. Pass `0` to disable cooldown for this run, overriding any
+  per-source or global configuration. See `cooldown` in bundle-config(1)
+  for details on the precedence between the CLI flag, Bundler config,
+  and Gemfile per-source settings.
+
+* `--force`, `--redownload`:
+  Force reinstalling every gem, even if already installed.
+
+* `--full-index`:
+  Bundler will not call Rubygems' API endpoint (default) but download and cache
+  a (currently big) index file of all gems. Performance can be improved for
+  large bundles that seldom change by enabling this option.
+
+* `--gemfile=GEMFILE`:
+  The location of the Gemfile(5) which Bundler should use. This defaults
+  to a Gemfile(5) in the current working directory. In general, Bundler
+  will assume that the location of the Gemfile(5) is also the project's
+  root and will try to find `Gemfile.lock` and `vendor/cache` relative
+  to this location.
+
+* `--jobs=<number>`, `-j=<number>`:
+  The maximum number of parallel download and install jobs. The default is the
+  number of available processors.
+
+* `--local`:
+  Do not attempt to connect to `rubygems.org`. Instead, Bundler will use the
+  gems already present in Rubygems' cache or in `vendor/cache`. Note that if an
+  appropriate platform-specific gem exists on `rubygems.org` it will not be
+  found.
+
+* `--lockfile=LOCKFILE`:
+  The location of the lockfile which Bundler should use. This defaults
+  to the Gemfile location with `.lock` appended.
+
+* `--prefer-local`:
+  Force using locally installed gems, or gems already present in Rubygems' cache
+  or in `vendor/cache`, when resolving, even if newer versions are available
+  remotely. Only attempt to connect to `rubygems.org` for gems that are not
+  present locally.
+
+* `--no-cache`:
+  Do not update the cache in `vendor/cache` with the newly bundled gems. This
+  does not remove any gems in the cache but keeps the newly bundled gems from
+  being cached during the install.
+
+* `--no-lock`:
+  Do not create a lockfile. Useful if you want to install dependencies but not
+  lock versions of gems. Recommended for library development, and other
+  situations where the code is expected to work with a range of dependency
+  versions.
+
+  This has the same effect as using `lockfile false` in the Gemfile.
+  See gemfile(5) for more information.
+
+* `--quiet`:
+  Do not print progress information to the standard output.
+
+* `--retry=[<number>]`:
+  Retry failed network or git requests for <number> times.
+
+* `--standalone[=<list>]`:
+  Makes a bundle that can work without depending on Rubygems or Bundler at
+  runtime. A space separated list of groups to install can be specified.
+  Bundler creates a directory named `bundle` and installs the bundle there. It
+  also generates a `bundle/bundler/setup.rb` file to replace Bundler's own setup
+  in the manner required.
+
+* `--trust-policy=TRUST-POLICY`:
+  Apply the Rubygems security policy <policy>, where policy is one of
+  `HighSecurity`, `MediumSecurity`, `LowSecurity`, `AlmostNoSecurity`, or
+  `NoSecurity`. For more details, please see the Rubygems signing documentation
+  linked below in [SEE ALSO][].
+
+* `--target-rbconfig=TARGET-RBCONFIG`:
+  Path to rbconfig.rb for the deployment target platform.
+
+## DEPLOYMENT MODE
+
+Bundler's defaults are optimized for development. To switch to
+defaults optimized for deployment and for CI, use the `deployment`
+setting. Do not activate deployment mode on development machines, as it
+will cause an error when the Gemfile(5) is modified.
+
+1. A `Gemfile.lock` is required.
+
+   To ensure that the same versions of the gems you developed with
+   and tested with are also used in deployments, a `Gemfile.lock`
+   is required.
+
+   This is mainly to ensure that you remember to check your
+   `Gemfile.lock` into version control.
+
+2. The `Gemfile.lock` must be up to date
+
+   In development, you can modify your Gemfile(5) and re-run
+   `bundle install` to [conservatively update][CONSERVATIVE UPDATING]
+   your `Gemfile.lock` snapshot.
+
+   In deployment, your `Gemfile.lock` should be up-to-date with
+   changes made in your Gemfile(5).
+
+3. Gems are installed to `vendor/bundle` not your default system location
+
+   In development, it's convenient to share the gems used in your
+   application with other applications and other scripts that run on
+   the system.
+
+   In deployment, isolation is a more important default. In addition,
+   the user deploying the application may not have permission to install
+   gems to the system, or the web server may not have permission to
+   read them.
+
+   As a result, when `deployment` is configured, `bundle install` installs gems
+   to the `vendor/bundle` directory in the application. This may be
+   overridden using the `path` setting.
+
+## INSTALLING GROUPS
+
+By default, `bundle install` will install all gems in all groups
+in your Gemfile(5), except those declared for a different platform.
+
+However, you can explicitly tell Bundler to skip installing
+certain groups with the `without` setting. This setting takes
+a space-separated list of groups.
+
+While the `without` setting will skip _installing_ the gems in the
+specified groups, `bundle install` will still _download_ those gems and use them
+to resolve the dependencies of every gem in your Gemfile(5).
+
+This is so that installing a different set of groups on another
+ machine (such as a production server) will not change the
+gems and versions that you have already developed and tested against.
+
+`Bundler offers a rock-solid guarantee that the third-party
+code you are running in development and testing is also the
+third-party code you are running in production. You can choose
+to exclude some of that code in different environments, but you
+will never be caught flat-footed by different versions of
+third-party code being used in different environments.`
+
+For a simple illustration, consider the following Gemfile(5):
+
+    source 'https://rubygems.org'
+
+    gem 'sinatra'
+
+    group :production do
+      gem 'rack-perftools-profiler'
+    end
+
+In this case, `sinatra` depends on any version of Rack (`>= 1.0`), while
+`rack-perftools-profiler` depends on 1.x (`~> 1.0`).
+
+When you configure `bundle config without production` in development, we
+look at the dependencies of `rack-perftools-profiler` as well. That way,
+you do not spend all your time developing against Rack 2.0, using new
+APIs unavailable in Rack 1.x, only to have Bundler switch to Rack 1.2
+when the `production` group _is_ used.
+
+This should not cause any problems in practice, because we do not
+attempt to `install` the gems in the excluded groups, and only evaluate
+as part of the dependency resolution process.
+
+This also means that you cannot include different versions of the same
+gem in different groups, because doing so would result in different
+sets of dependencies used in development and production. Because of
+the vagaries of the dependency resolution process, this usually
+affects more than the gems you list in your Gemfile(5), and can
+(surprisingly) radically change the gems you are using.
+
+## THE GEMFILE.LOCK
+
+When you run `bundle install`, Bundler will persist the full names
+and versions of all gems that you used (including dependencies of
+the gems specified in the Gemfile(5)) into a file called `Gemfile.lock`.
+
+Bundler uses this file in all subsequent calls to `bundle install`,
+which guarantees that you always use the same exact code, even
+as your application moves across machines.
+
+Because of the way dependency resolution works, even a
+seemingly small change (for instance, an update to a point-release
+of a dependency of a gem in your Gemfile(5)) can result in radically
+different gems being needed to satisfy all dependencies.
+
+As a result, you `SHOULD` check your `Gemfile.lock` into version
+control, in both applications and gems. If you do not, every machine that
+checks out your repository (including your production server) will resolve all
+dependencies again, which will result in different versions of
+third-party code being used if `any` of the gems in the Gemfile(5)
+or any of their dependencies have been updated.
+
+When Bundler first shipped, the `Gemfile.lock` was included in the `.gitignore`
+file included with generated gems.  Over time, however, it became clear that
+this practice forces the pain of broken dependencies onto new contributors,
+while leaving existing contributors potentially unaware of the problem. Since
+`bundle install` is usually the first step towards a contribution, the pain of
+broken dependencies would discourage new contributors from contributing. As a
+result, we have revised our guidance for gem authors to now recommend checking
+in the lock for gems.
+
+## CONSERVATIVE UPDATING
+
+When you make a change to the Gemfile(5) and then run `bundle install`,
+Bundler will update only the gems that you modified.
+
+In other words, if a gem that you `did not modify` worked before
+you called `bundle install`, it will continue to use the exact
+same versions of all dependencies as it used before the update.
+
+Let's take a look at an example. Here's your original Gemfile(5):
+
+    source 'https://rubygems.org'
+
+    gem 'actionpack', '2.3.8'
+    gem 'activemerchant'
+
+In this case, both `actionpack` and `activemerchant` depend on
+`activesupport`. The `actionpack` gem depends on `activesupport 2.3.8`
+and `rack ~> 1.1.0`, while the `activemerchant` gem depends on
+`activesupport >= 2.3.2`, `braintree >= 2.0.0`, and `builder >= 2.0.0`.
+
+When the dependencies are first resolved, Bundler will select
+`activesupport 2.3.8`, which satisfies the requirements of both
+gems in your Gemfile(5).
+
+Next, you modify your Gemfile(5) to:
+
+    source 'https://rubygems.org'
+
+    gem 'actionpack', '3.0.0.rc'
+    gem 'activemerchant'
+
+The `actionpack 3.0.0.rc` gem has a number of new dependencies,
+and updates the `activesupport` dependency to `= 3.0.0.rc` and
+the `rack` dependency to `~> 1.2.1`.
+
+When you run `bundle install`, Bundler notices that you changed
+the `actionpack` gem, but not the `activemerchant` gem. It
+evaluates the gems currently being used to satisfy its requirements:
+
+  * `activesupport 2.3.8`:
+    also used to satisfy a dependency in `activemerchant`,
+    which is not being updated
+  * `rack ~> 1.1.0`:
+    not currently being used to satisfy another dependency
+
+Because you did not explicitly ask to update `activemerchant`,
+you would not expect it to suddenly stop working after updating
+`actionpack`. However, satisfying the new `activesupport 3.0.0.rc`
+dependency of actionpack requires updating one of its dependencies.
+
+Even though `activemerchant` declares a very loose dependency
+that theoretically matches `activesupport 3.0.0.rc`, Bundler treats
+gems in your Gemfile(5) that have not changed as an atomic unit
+together with their dependencies. In this case, the `activemerchant`
+dependency is treated as `activemerchant 1.7.1 + activesupport 2.3.8`,
+so `bundle install` will report that it cannot update `actionpack`.
+
+To explicitly update `actionpack`, including its dependencies
+which other gems in the Gemfile(5) still depend on, run
+`bundle update actionpack` (see `bundle update(1)`).
+
+`Summary`: In general, after making a change to the Gemfile(5) , you
+should first try to run `bundle install`, which will guarantee that no
+other gem in the Gemfile(5) is impacted by the change. If that
+does not work, run [bundle update(1)](bundle-update.1.html).
+
+## SEE ALSO
+
+* [Gem install docs](https://guides.rubygems.org/rubygems-basics/#installing-gems)
+* [Rubygems signing docs](https://guides.rubygems.org/security/)
diff --git a/lib/bundler/man/bundle-issue.1 b/lib/bundler/man/bundle-issue.1
new file mode 100644
index 0000000000..3af277ef86
--- /dev/null
+++ b/lib/bundler/man/bundle-issue.1
@@ -0,0 +1,45 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-ISSUE" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-issue\fR \- Get help reporting Bundler issues
+.SH "SYNOPSIS"
+\fBbundle issue\fR
+.SH "DESCRIPTION"
+Provides guidance on reporting Bundler issues and outputs detailed system information that should be included when filing a bug report\. This command:
+.IP "1." 4
+Displays links to troubleshooting resources
+.IP "2." 4
+Shows instructions for reporting issues
+.IP "3." 4
+Outputs comprehensive environment information needed for debugging
+.IP "" 0
+.P
+The command helps ensure that bug reports include all necessary system details for effective troubleshooting\.
+.SH "OUTPUT"
+The command outputs several sections:
+.IP "\(bu" 4
+Troubleshooting links and resources
+.IP "\(bu" 4
+Link to the GitHub issue template
+.IP "\(bu" 4
+Environment information including: Bundler version and platforms, Ruby version and configuration, RubyGems version and paths, Development tool versions (Git, RVM, rbenv, chruby)
+.IP "\(bu" 4
+Bundler build metadata
+.IP "\(bu" 4
+Current Bundler settings
+.IP "\(bu" 4
+Bundle Doctor output
+.IP "" 0
+.SH "EXAMPLES"
+Get issue reporting information:
+.IP "" 4
+.nf
+$ bundle issue
+.fi
+.IP "" 0
+.SH "SEE ALSO"
+.IP "\(bu" 4
+bundle\-doctor(1)
+.IP "" 0
+
diff --git a/lib/bundler/man/bundle-issue.1.ronn b/lib/bundler/man/bundle-issue.1.ronn
new file mode 100644
index 0000000000..37f676a354
--- /dev/null
+++ b/lib/bundler/man/bundle-issue.1.ronn
@@ -0,0 +1,37 @@
+bundle-issue(1) -- Get help reporting Bundler issues
+====================================================
+
+## SYNOPSIS
+
+`bundle issue`
+
+## DESCRIPTION
+
+Provides guidance on reporting Bundler issues and outputs detailed system information that should be included when filing a bug report. This command:
+
+1. Displays links to troubleshooting resources
+2. Shows instructions for reporting issues
+3. Outputs comprehensive environment information needed for debugging
+
+The command helps ensure that bug reports include all necessary system details for effective troubleshooting.
+
+## OUTPUT
+
+The command outputs several sections:
+
+* Troubleshooting links and resources
+* Link to the GitHub issue template
+* Environment information including: Bundler version and platforms, Ruby version and configuration, RubyGems version and paths, Development tool versions (Git, RVM, rbenv, chruby)
+* Bundler build metadata
+* Current Bundler settings
+* Bundle Doctor output
+
+## EXAMPLES
+
+Get issue reporting information:
+
+    $ bundle issue
+
+## SEE ALSO
+
+* bundle-doctor(1)
diff --git a/lib/bundler/man/bundle-licenses.1 b/lib/bundler/man/bundle-licenses.1
new file mode 100644
index 0000000000..ab5996d2be
--- /dev/null
+++ b/lib/bundler/man/bundle-licenses.1
@@ -0,0 +1,9 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-LICENSES" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-licenses\fR \- Print the license of all gems in the bundle
+.SH "SYNOPSIS"
+\fBbundle licenses\fR
+.SH "DESCRIPTION"
+Prints the license of all gems in the bundle\.
diff --git a/lib/bundler/man/bundle-licenses.1.ronn b/lib/bundler/man/bundle-licenses.1.ronn
new file mode 100644
index 0000000000..91caba6c2a
--- /dev/null
+++ b/lib/bundler/man/bundle-licenses.1.ronn
@@ -0,0 +1,10 @@
+bundle-licenses(1) -- Print the license of all gems in the bundle
+=================================================================
+
+## SYNOPSIS
+
+`bundle licenses`
+
+## DESCRIPTION
+
+Prints the license of all gems in the bundle.
diff --git a/lib/bundler/man/bundle-list.1 b/lib/bundler/man/bundle-list.1
new file mode 100644
index 0000000000..e759e0d449
--- /dev/null
+++ b/lib/bundler/man/bundle-list.1
@@ -0,0 +1,40 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-LIST" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-list\fR \- List all the gems in the bundle
+.SH "SYNOPSIS"
+\fBbundle list\fR [\-\-name\-only] [\-\-paths] [\-\-without\-group=GROUP[ GROUP\|\.\|\.\|\.]] [\-\-only\-group=GROUP[ GROUP\|\.\|\.\|\.]]
+.SH "DESCRIPTION"
+Prints a list of all the gems in the bundle including their version\.
+.P
+Example:
+.P
+bundle list \-\-name\-only
+.P
+bundle list \-\-paths
+.P
+bundle list \-\-without\-group test
+.P
+bundle list \-\-only\-group dev
+.P
+bundle list \-\-only\-group dev test \-\-paths
+.P
+bundle list \-\-format json
+.SH "OPTIONS"
+.TP
+\fB\-\-name\-only\fR
+Print only the name of each gem\.
+.TP
+\fB\-\-paths\fR
+Print the path to each gem in the bundle\.
+.TP
+\fB\-\-without\-group=<list>\fR
+A space\-separated list of groups of gems to skip during printing\.
+.TP
+\fB\-\-only\-group=<list>\fR
+A space\-separated list of groups of gems to print\.
+.TP
+\fB\-\-format=FORMAT\fR
+Format output ('json' is the only supported format)
+
diff --git a/lib/bundler/man/bundle-list.1.ronn b/lib/bundler/man/bundle-list.1.ronn
new file mode 100644
index 0000000000..9ec2b13282
--- /dev/null
+++ b/lib/bundler/man/bundle-list.1.ronn
@@ -0,0 +1,41 @@
+bundle-list(1) -- List all the gems in the bundle
+=================================================
+
+## SYNOPSIS
+
+`bundle list` [--name-only] [--paths] [--without-group=GROUP[ GROUP...]] [--only-group=GROUP[ GROUP...]]
+
+## DESCRIPTION
+
+Prints a list of all the gems in the bundle including their version.
+
+Example:
+
+bundle list --name-only
+
+bundle list --paths
+
+bundle list --without-group test
+
+bundle list --only-group dev
+
+bundle list --only-group dev test --paths
+
+bundle list --format json
+
+## OPTIONS
+
+* `--name-only`:
+  Print only the name of each gem.
+
+* `--paths`:
+  Print the path to each gem in the bundle.
+
+* `--without-group=<list>`:
+  A space-separated list of groups of gems to skip during printing.
+
+* `--only-group=<list>`:
+  A space-separated list of groups of gems to print.
+
+* `--format=FORMAT`:
+  Format output ('json' is the only supported format)
diff --git a/lib/bundler/man/bundle-lock.1 b/lib/bundler/man/bundle-lock.1
new file mode 100644
index 0000000000..396c8ff6ca
--- /dev/null
+++ b/lib/bundler/man/bundle-lock.1
@@ -0,0 +1,75 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-LOCK" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-lock\fR \- Creates / Updates a lockfile without installing
+.SH "SYNOPSIS"
+\fBbundle lock\fR [\-\-update] [\-\-bundler[=BUNDLER]] [\-\-local] [\-\-print] [\-\-lockfile=PATH] [\-\-full\-index] [\-\-gemfile=GEMFILE] [\-\-add\-checksums] [\-\-add\-platform] [\-\-remove\-platform] [\-\-normalize\-platforms] [\-\-patch] [\-\-minor] [\-\-major] [\-\-pre] [\-\-strict] [\-\-conservative]
+.SH "DESCRIPTION"
+Lock the gems specified in Gemfile\.
+.SH "OPTIONS"
+.TP
+\fB\-\-update[=<list>]\fR
+Ignores the existing lockfile\. Resolve then updates lockfile\. Taking a list of gems or updating all gems if no list is given\.
+.TP
+\fB\-\-bundler[=BUNDLER]\fR
+Update the locked version of bundler to the given version or the latest version if no version is given\.
+.TP
+\fB\-\-local\fR
+Do not attempt to connect to \fBrubygems\.org\fR\. Instead, Bundler will use the gems already present in Rubygems' cache or in \fBvendor/cache\fR\. Note that if a appropriate platform\-specific gem exists on \fBrubygems\.org\fR it will not be found\.
+.TP
+\fB\-\-print\fR
+Prints the lockfile to STDOUT instead of writing to the file system\.
+.TP
+\fB\-\-lockfile=LOCKFILE\fR
+The path where the lockfile should be written to\.
+.TP
+\fB\-\-full\-index\fR
+Fall back to using the single\-file index of all gems\.
+.TP
+\fB\-\-gemfile=GEMFILE\fR
+Use the specified gemfile instead of [\fBGemfile(5)\fR][Gemfile(5)]\.
+.TP
+\fB\-\-add\-checksums\fR
+Add checksums to the lockfile\.
+.TP
+\fB\-\-add\-platform=<list>\fR
+Add a new platform to the lockfile, re\-resolving for the addition of that platform\.
+.TP
+\fB\-\-remove\-platform=<list>\fR
+Remove a platform from the lockfile\.
+.TP
+\fB\-\-normalize\-platforms\fR
+Normalize lockfile platforms\.
+.TP
+\fB\-\-patch\fR
+If updating, prefer updating only to next patch version\.
+.TP
+\fB\-\-minor\fR
+If updating, prefer updating only to next minor version\.
+.TP
+\fB\-\-major\fR
+If updating, prefer updating to next major version (default)\.
+.TP
+\fB\-\-pre\fR
+If updating, always choose the highest allowed version, regardless of prerelease status\.
+.TP
+\fB\-\-strict\fR
+If updating, do not allow any gem to be updated past latest \-\-patch | \-\-minor | \-\-major\.
+.TP
+\fB\-\-conservative\fR
+If updating, use bundle install conservative update behavior and do not allow shared dependencies to be updated\.
+.SH "UPDATING ALL GEMS"
+If you run \fBbundle lock\fR with \fB\-\-update\fR option without list of gems, bundler will ignore any previously installed gems and resolve all dependencies again based on the latest versions of all gems available in the sources\.
+.SH "UPDATING A LIST OF GEMS"
+Sometimes, you want to update a single gem in the Gemfile(5), and leave the rest of the gems that you specified locked to the versions in the \fBGemfile\.lock\fR\.
+.P
+For instance, you only want to update \fBnokogiri\fR, run \fBbundle lock \-\-update nokogiri\fR\.
+.P
+Bundler will update \fBnokogiri\fR and any of its dependencies, but leave the rest of the gems that you specified locked to the versions in the \fBGemfile\.lock\fR\.
+.SH "SUPPORTING OTHER PLATFORMS"
+If you want your bundle to support platforms other than the one you're running locally, you can run \fBbundle lock \-\-add\-platform PLATFORM\fR to add PLATFORM to the lockfile, force bundler to re\-resolve and consider the new platform when picking gems, all without needing to have a machine that matches PLATFORM handy to install those platform\-specific gems on\.
+.P
+For a full explanation of gem platforms, see \fBgem help platform\fR\.
+.SH "PATCH LEVEL OPTIONS"
+See bundle update(1) \fIbundle\-update\.1\.html\fR for details\.
diff --git a/lib/bundler/man/bundle-lock.1.ronn b/lib/bundler/man/bundle-lock.1.ronn
new file mode 100644
index 0000000000..6d3e63c982
--- /dev/null
+++ b/lib/bundler/man/bundle-lock.1.ronn
@@ -0,0 +1,115 @@
+bundle-lock(1) -- Creates / Updates a lockfile without installing
+=================================================================
+
+## SYNOPSIS
+
+`bundle lock` [--update]
+              [--bundler[=BUNDLER]]
+              [--local]
+              [--print]
+              [--lockfile=PATH]
+              [--full-index]
+              [--gemfile=GEMFILE]
+              [--add-checksums]
+              [--add-platform]
+              [--remove-platform]
+              [--normalize-platforms]
+              [--patch]
+              [--minor]
+              [--major]
+              [--pre]
+              [--strict]
+              [--conservative]
+
+## DESCRIPTION
+
+Lock the gems specified in Gemfile.
+
+## OPTIONS
+
+* `--update[=<list>]`:
+  Ignores the existing lockfile. Resolve then updates lockfile. Taking a list
+  of gems or updating all gems if no list is given.
+
+* `--bundler[=BUNDLER]`:
+  Update the locked version of bundler to the given version or the latest
+  version if no version is given.
+
+* `--local`:
+  Do not attempt to connect to `rubygems.org`. Instead, Bundler will use the
+  gems already present in Rubygems' cache or in `vendor/cache`. Note that if a
+  appropriate platform-specific gem exists on `rubygems.org` it will not be
+  found.
+
+* `--print`:
+  Prints the lockfile to STDOUT instead of writing to the file system.
+
+* `--lockfile=LOCKFILE`:
+  The path where the lockfile should be written to.
+
+* `--full-index`:
+  Fall back to using the single-file index of all gems.
+
+* `--gemfile=GEMFILE`:
+  Use the specified gemfile instead of [`Gemfile(5)`][Gemfile(5)].
+
+* `--add-checksums`:
+  Add checksums to the lockfile.
+
+* `--add-platform=<list>`:
+  Add a new platform to the lockfile, re-resolving for the addition of that
+  platform.
+
+* `--remove-platform=<list>`:
+  Remove a platform from the lockfile.
+
+* `--normalize-platforms`:
+  Normalize lockfile platforms.
+
+* `--patch`:
+  If updating, prefer updating only to next patch version.
+
+* `--minor`:
+  If updating, prefer updating only to next minor version.
+
+* `--major`:
+  If updating, prefer updating to next major version (default).
+
+* `--pre`:
+  If updating, always choose the highest allowed version, regardless of prerelease status.
+
+* `--strict`:
+  If updating, do not allow any gem to be updated past latest --patch | --minor | --major.
+
+* `--conservative`:
+  If updating, use bundle install conservative update behavior and do not allow shared dependencies to be updated.
+
+## UPDATING ALL GEMS
+
+If you run `bundle lock` with `--update` option without list of gems, bundler will
+ignore any previously installed gems and resolve all dependencies again based
+on the latest versions of all gems available in the sources.
+
+## UPDATING A LIST OF GEMS
+
+Sometimes, you want to update a single gem in the Gemfile(5), and leave the rest of
+the gems that you specified locked to the versions in the `Gemfile.lock`.
+
+For instance, you only want to update `nokogiri`, run `bundle lock --update nokogiri`.
+
+Bundler will update `nokogiri` and any of its dependencies, but leave the rest of the
+gems that you specified locked to the versions in the `Gemfile.lock`.
+
+## SUPPORTING OTHER PLATFORMS
+
+If you want your bundle to support platforms other than the one you're running
+locally, you can run `bundle lock --add-platform PLATFORM` to add PLATFORM to
+the lockfile, force bundler to re-resolve and consider the new platform when
+picking gems, all without needing to have a machine that matches PLATFORM handy
+to install those platform-specific gems on.
+
+For a full explanation of gem platforms, see `gem help platform`.
+
+## PATCH LEVEL OPTIONS
+
+See [bundle update(1)](bundle-update.1.html) for details.
diff --git a/lib/bundler/man/bundle-open.1 b/lib/bundler/man/bundle-open.1
new file mode 100644
index 0000000000..2aab59f14b
--- /dev/null
+++ b/lib/bundler/man/bundle-open.1
@@ -0,0 +1,32 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-OPEN" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-open\fR \- Opens the source directory for a gem in your bundle
+.SH "SYNOPSIS"
+\fBbundle open\fR [GEM] [\-\-path=PATH]
+.SH "DESCRIPTION"
+Opens the source directory of the provided GEM in your editor\.
+.P
+For this to work the \fBEDITOR\fR or \fBBUNDLER_EDITOR\fR environment variable has to be set\.
+.P
+Example:
+.IP "" 4
+.nf
+bundle open 'rack'
+.fi
+.IP "" 0
+.P
+Will open the source directory for the 'rack' gem in your bundle\.
+.IP "" 4
+.nf
+bundle open 'rack' \-\-path 'README\.md'
+.fi
+.IP "" 0
+.P
+Will open the README\.md file of the 'rack' gem source in your bundle\.
+.SH "OPTIONS"
+.TP
+\fB\-\-path[=PATH]\fR
+Specify GEM source relative path to open\.
+
diff --git a/lib/bundler/man/bundle-open.1.ronn b/lib/bundler/man/bundle-open.1.ronn
new file mode 100644
index 0000000000..24dbe97e44
--- /dev/null
+++ b/lib/bundler/man/bundle-open.1.ronn
@@ -0,0 +1,28 @@
+bundle-open(1) -- Opens the source directory for a gem in your bundle
+=====================================================================
+
+## SYNOPSIS
+
+`bundle open` [GEM] [--path=PATH]
+
+## DESCRIPTION
+
+Opens the source directory of the provided GEM in your editor.
+
+For this to work the `EDITOR` or `BUNDLER_EDITOR` environment variable has to
+be set.
+
+Example:
+
+    bundle open 'rack'
+
+Will open the source directory for the 'rack' gem in your bundle.
+
+    bundle open 'rack' --path 'README.md'
+
+Will open the README.md file of the 'rack' gem source in your bundle.
+
+## OPTIONS
+
+* `--path[=PATH]`:
+  Specify GEM source relative path to open.
diff --git a/lib/bundler/man/bundle-outdated.1 b/lib/bundler/man/bundle-outdated.1
new file mode 100644
index 0000000000..c2f8086e24
--- /dev/null
+++ b/lib/bundler/man/bundle-outdated.1
@@ -0,0 +1,106 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-OUTDATED" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-outdated\fR \- List installed gems with newer versions available
+.SH "SYNOPSIS"
+\fBbundle outdated\fR [GEM] [\-\-local] [\-\-pre] [\-\-source] [\-\-filter\-strict | \-\-strict] [\-\-update\-strict] [\-\-parseable | \-\-porcelain] [\-\-group=GROUP] [\-\-groups] [\-\-patch|\-\-minor|\-\-major] [\-\-filter\-major] [\-\-filter\-minor] [\-\-filter\-patch] [\-\-only\-explicit] [\-\-cooldown=NUMBER]
+.SH "DESCRIPTION"
+Outdated lists the names and versions of gems that have a newer version available in the given source\. Calling outdated with [GEM [GEM]] will only check for newer versions of the given gems\. Prerelease gems are ignored by default\. If your gems are up to date, Bundler will exit with a status of 0\. Otherwise, it will exit 1\.
+.SH "OPTIONS"
+.TP
+\fB\-\-local\fR
+Do not attempt to fetch gems remotely and use the gem cache instead\.
+.TP
+\fB\-\-pre\fR
+Check for newer pre\-release gems\.
+.TP
+\fB\-\-source=<list>\fR
+Check against a specific source\.
+.TP
+\fB\-\-filter\-strict\fR, \fB\-\-strict\fR
+Only list newer versions allowed by your Gemfile requirements, also respecting conservative update flags (\-\-patch, \-\-minor, \-\-major)\.
+.TP
+\fB\-\-update\-strict\fR
+Strict conservative resolution, do not allow any gem to be updated past latest \-\-patch | \-\-minor | \-\-major\.
+.TP
+\fB\-\-parseable\fR, \fB\-\-porcelain\fR
+Use minimal formatting for more parseable output\.
+.TP
+\fB\-\-group=GROUP\fR
+List gems from a specific group\.
+.TP
+\fB\-\-groups\fR
+List gems organized by groups\.
+.TP
+\fB\-\-minor\fR
+Prefer updating only to next minor version\.
+.TP
+\fB\-\-major\fR
+Prefer updating to next major version (default)\.
+.TP
+\fB\-\-patch\fR
+Prefer updating only to next patch version\.
+.TP
+\fB\-\-filter\-major\fR
+Only list major newer versions\.
+.TP
+\fB\-\-filter\-minor\fR
+Only list minor newer versions\.
+.TP
+\fB\-\-filter\-patch\fR
+Only list patch newer versions\.
+.TP
+\fB\-\-only\-explicit\fR
+Only list gems specified in your Gemfile, not their dependencies\.
+.TP
+\fB\-\-cooldown=<number>\fR
+Annotate (rather than hide) versions that are still inside the cooldown window of \fInumber\fR days\. The prose output appends "in cooldown for Nd more days" and the table form adds "(cooldown Nd)" to the Latest column\. See \fBcooldown\fR in bundle\-config(1)\.
+.SH "PATCH LEVEL OPTIONS"
+See bundle update(1) \fIbundle\-update\.1\.html\fR for details\.
+.SH "FILTERING OUTPUT"
+The 3 filtering options do not affect the resolution of versions, merely what versions are shown in the output\.
+.P
+If the regular output shows the following:
+.IP "" 4
+.nf
+* Gem       Current  Latest  Requested  Groups              Release Date
+* faker     1\.6\.5    1\.6\.6   ~> 1\.4     development, test   2024\-02\-05
+* hashie    1\.2\.0    3\.4\.6   = 1\.2\.0    default             2023\-11\-10
+* headless  2\.2\.3    2\.3\.1   = 2\.2\.3    test                2022\-08\-19
+.fi
+.IP "" 0
+.P
+\fB\-\-filter\-major\fR would only show:
+.IP "" 4
+.nf
+* Gem       Current  Latest  Requested  Groups   Release Date
+* hashie    1\.2\.0    3\.4\.6   = 1\.2\.0    default  2023\-11\-10
+.fi
+.IP "" 0
+.P
+\fB\-\-filter\-minor\fR would only show:
+.IP "" 4
+.nf
+* Gem       Current  Latest  Requested  Groups  Release Date
+* headless  2\.2\.3    2\.3\.1   = 2\.2\.3    test    2022\-08\-19
+.fi
+.IP "" 0
+.P
+\fB\-\-filter\-patch\fR would only show:
+.IP "" 4
+.nf
+* Gem       Current  Latest  Requested  Groups              Release Date
+* faker     1\.6\.5    1\.6\.6   ~> 1\.4     development, test   2024\-02\-05
+.fi
+.IP "" 0
+.P
+Filter options can be combined\. \fB\-\-filter\-minor\fR and \fB\-\-filter\-patch\fR would show:
+.IP "" 4
+.nf
+* Gem       Current  Latest  Requested  Groups              Release Date
+* faker     1\.6\.5    1\.6\.6   ~> 1\.4     development, test   2024\-02\-05
+.fi
+.IP "" 0
+.P
+Combining all three \fBfilter\fR options would be the same result as providing none of them\.
diff --git a/lib/bundler/man/bundle-outdated.1.ronn b/lib/bundler/man/bundle-outdated.1.ronn
new file mode 100644
index 0000000000..e5badac2e9
--- /dev/null
+++ b/lib/bundler/man/bundle-outdated.1.ronn
@@ -0,0 +1,117 @@
+bundle-outdated(1) -- List installed gems with newer versions available
+=======================================================================
+
+## SYNOPSIS
+
+`bundle outdated` [GEM] [--local]
+                        [--pre]
+                        [--source]
+                        [--filter-strict | --strict]
+                        [--update-strict]
+                        [--parseable | --porcelain]
+                        [--group=GROUP]
+                        [--groups]
+                        [--patch|--minor|--major]
+                        [--filter-major]
+                        [--filter-minor]
+                        [--filter-patch]
+                        [--only-explicit]
+                        [--cooldown=NUMBER]
+
+## DESCRIPTION
+
+Outdated lists the names and versions of gems that have a newer version available
+in the given source. Calling outdated with [GEM [GEM]] will only check for newer
+versions of the given gems. Prerelease gems are ignored by default. If your gems
+are up to date, Bundler will exit with a status of 0. Otherwise, it will exit 1.
+
+## OPTIONS
+
+* `--local`:
+  Do not attempt to fetch gems remotely and use the gem cache instead.
+
+* `--pre`:
+  Check for newer pre-release gems.
+
+* `--source=<list>`:
+  Check against a specific source.
+
+* `--filter-strict`, `--strict`:
+  Only list newer versions allowed by your Gemfile requirements, also respecting conservative update flags (--patch, --minor, --major).
+
+* `--update-strict`:
+  Strict conservative resolution, do not allow any gem to be updated past latest --patch | --minor | --major.
+
+* `--parseable`, `--porcelain`:
+   Use minimal formatting for more parseable output.
+
+* `--group=GROUP`:
+  List gems from a specific group.
+
+* `--groups`:
+  List gems organized by groups.
+
+* `--minor`:
+  Prefer updating only to next minor version.
+
+* `--major`:
+  Prefer updating to next major version (default).
+
+* `--patch`:
+  Prefer updating only to next patch version.
+
+* `--filter-major`:
+  Only list major newer versions.
+
+* `--filter-minor`:
+  Only list minor newer versions.
+
+* `--filter-patch`:
+  Only list patch newer versions.
+
+* `--only-explicit`:
+  Only list gems specified in your Gemfile, not their dependencies.
+
+* `--cooldown=<number>`:
+  Annotate (rather than hide) versions that are still inside the
+  cooldown window of <number> days. The prose output appends "in
+  cooldown for Nd more days" and the table form adds "(cooldown Nd)" to
+  the Latest column. See `cooldown` in bundle-config(1).
+
+## PATCH LEVEL OPTIONS
+
+See [bundle update(1)](bundle-update.1.html) for details.
+
+## FILTERING OUTPUT
+
+The 3 filtering options do not affect the resolution of versions, merely what versions are shown
+in the output.
+
+If the regular output shows the following:
+
+    * Gem       Current  Latest  Requested  Groups              Release Date
+    * faker     1.6.5    1.6.6   ~> 1.4     development, test   2024-02-05
+    * hashie    1.2.0    3.4.6   = 1.2.0    default             2023-11-10
+    * headless  2.2.3    2.3.1   = 2.2.3    test                2022-08-19
+
+`--filter-major` would only show:
+
+    * Gem       Current  Latest  Requested  Groups   Release Date
+    * hashie    1.2.0    3.4.6   = 1.2.0    default  2023-11-10
+
+`--filter-minor` would only show:
+
+    * Gem       Current  Latest  Requested  Groups  Release Date
+    * headless  2.2.3    2.3.1   = 2.2.3    test    2022-08-19
+
+`--filter-patch` would only show:
+
+    * Gem       Current  Latest  Requested  Groups              Release Date
+    * faker     1.6.5    1.6.6   ~> 1.4     development, test   2024-02-05
+
+Filter options can be combined. `--filter-minor` and `--filter-patch` would show:
+
+    * Gem       Current  Latest  Requested  Groups              Release Date
+    * faker     1.6.5    1.6.6   ~> 1.4     development, test   2024-02-05
+
+Combining all three `filter` options would be the same result as providing none of them.
diff --git a/lib/bundler/man/bundle-platform.1 b/lib/bundler/man/bundle-platform.1
new file mode 100644
index 0000000000..39b7111263
--- /dev/null
+++ b/lib/bundler/man/bundle-platform.1
@@ -0,0 +1,49 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-PLATFORM" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-platform\fR \- Displays platform compatibility information
+.SH "SYNOPSIS"
+\fBbundle platform\fR [\-\-ruby]
+.SH "DESCRIPTION"
+\fBplatform\fR displays information from your Gemfile, Gemfile\.lock, and Ruby VM about your platform\.
+.P
+For instance, using this Gemfile(5):
+.IP "" 4
+.nf
+source "https://rubygems\.org"
+
+ruby "3\.1\.2"
+
+gem "rack"
+.fi
+.IP "" 0
+.P
+If you run \fBbundle platform\fR on Ruby 3\.1\.2, it displays the following output:
+.IP "" 4
+.nf
+Your platform is: x86_64\-linux
+
+Your app has gems that work on these platforms:
+* arm64\-darwin\-21
+* ruby
+* x64\-mingw\-ucrt
+* x86_64\-linux
+
+Your Gemfile specifies a Ruby version requirement:
+* ruby 3\.1\.2
+
+Your current platform satisfies the Ruby version requirement\.
+.fi
+.IP "" 0
+.P
+\fBplatform\fR lists all the platforms in your \fBGemfile\.lock\fR as well as the \fBruby\fR directive if applicable from your Gemfile(5)\. It also lets you know if the \fBruby\fR directive requirement has been met\. If \fBruby\fR directive doesn't match the running Ruby VM, it tells you what part does not\.
+.SH "OPTIONS"
+.TP
+\fB\-\-ruby\fR
+It will display the ruby directive information, so you don't have to parse it from the Gemfile(5)\.
+.SH "SEE ALSO"
+.IP "\(bu" 4
+bundle\-lock(1) \fIbundle\-lock\.1\.html\fR
+.IP "" 0
+
diff --git a/lib/bundler/man/bundle-platform.1.ronn b/lib/bundler/man/bundle-platform.1.ronn
new file mode 100644
index 0000000000..744acd1b43
--- /dev/null
+++ b/lib/bundler/man/bundle-platform.1.ronn
@@ -0,0 +1,49 @@
+bundle-platform(1) -- Displays platform compatibility information
+=================================================================
+
+## SYNOPSIS
+
+`bundle platform` [--ruby]
+
+## DESCRIPTION
+
+`platform` displays information from your Gemfile, Gemfile.lock, and Ruby
+VM about your platform.
+
+For instance, using this Gemfile(5):
+
+    source "https://rubygems.org"
+
+    ruby "3.1.2"
+
+    gem "rack"
+
+If you run `bundle platform` on Ruby 3.1.2, it displays the following output:
+
+    Your platform is: x86_64-linux
+
+    Your app has gems that work on these platforms:
+    * arm64-darwin-21
+    * ruby
+    * x64-mingw-ucrt
+    * x86_64-linux
+
+    Your Gemfile specifies a Ruby version requirement:
+    * ruby 3.1.2
+
+    Your current platform satisfies the Ruby version requirement.
+
+`platform` lists all the platforms in your `Gemfile.lock` as well as the
+`ruby` directive if applicable from your Gemfile(5). It also lets you know
+if the `ruby` directive requirement has been met. If `ruby` directive doesn't
+match the running Ruby VM, it tells you what part does not.
+
+## OPTIONS
+
+* `--ruby`:
+  It will display the ruby directive information, so you don't have to
+  parse it from the Gemfile(5).
+
+## SEE ALSO
+
+* [bundle-lock(1)](bundle-lock.1.html)
diff --git a/lib/bundler/man/bundle-plugin.1 b/lib/bundler/man/bundle-plugin.1
new file mode 100644
index 0000000000..d182c7789b
--- /dev/null
+++ b/lib/bundler/man/bundle-plugin.1
@@ -0,0 +1,76 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-PLUGIN" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-plugin\fR \- Manage Bundler plugins
+.SH "SYNOPSIS"
+\fBbundle plugin\fR install PLUGINS [\-\-source=SOURCE] [\-\-version=VERSION] [\-\-git=GIT] [\-\-branch=BRANCH|\-\-ref=REF] [\-\-path=PATH]
+.br
+\fBbundle plugin\fR uninstall PLUGINS [\-\-all]
+.br
+\fBbundle plugin\fR list
+.br
+\fBbundle plugin\fR help [COMMAND]
+.SH "DESCRIPTION"
+You can install, uninstall, and list plugin(s) with this command to extend functionalities of Bundler\.
+.SH "SUB\-COMMANDS"
+.SS "install"
+Install the given plugin(s)\.
+.P
+For example, \fBbundle plugin install bundler\-graph\fR will install bundler\-graph gem from globally configured sources (defaults to RubyGems\.org)\. Note that the global source specified in Gemfile is ignored\.
+.P
+\fBOPTIONS\fR
+.TP
+\fB\-\-source=SOURCE\fR
+Install the plugin gem from a specific source, rather than from globally configured sources\.
+.IP
+Example: \fBbundle plugin install bundler\-graph \-\-source https://example\.com\fR
+.TP
+\fB\-\-version=VERSION\fR
+Specify a version of the plugin gem to install via \fB\-\-version\fR\.
+.IP
+Example: \fBbundle plugin install bundler\-graph \-\-version 0\.2\.1\fR
+.TP
+\fB\-\-git=GIT\fR
+Install the plugin gem from a Git repository\. You can use standard Git URLs like:
+.IP
+\fBssh://[user@]host\.xz[:port]/path/to/repo\.git\fR
+.br
+\fBhttp[s]://host\.xz[:port]/path/to/repo\.git\fR
+.br
+\fB/path/to/repo\fR
+.br
+\fBfile:///path/to/repo\fR
+.IP
+Example: \fBbundle plugin install bundler\-graph \-\-git https://github\.com/rubygems/bundler\-graph\fR
+.TP
+\fB\-\-branch=BRANCH\fR
+When you specify \fB\-\-git\fR, you can use \fB\-\-branch\fR to use\.
+.TP
+\fB\-\-ref=REF\fR
+When you specify \fB\-\-git\fR, you can use \fB\-\-ref\fR to specify any tag, or commit hash (revision) to use\.
+.TP
+\fB\-\-path=PATH\fR
+Install the plugin gem from a local path\.
+.IP
+Example: \fBbundle plugin install bundler\-graph \-\-path \.\./bundler\-graph\fR
+.SS "uninstall"
+Uninstall the plugin(s) specified in PLUGINS\.
+.P
+\fBOPTIONS\fR
+.TP
+\fB\-\-all\fR
+Uninstall all the installed plugins\. If no plugin is installed, then it does nothing\.
+.SS "list"
+List the installed plugins and available commands\.
+.P
+No options\.
+.SS "help"
+Describe subcommands or one specific subcommand\.
+.P
+No options\.
+.SH "SEE ALSO"
+.IP "\(bu" 4
+How to write a Bundler plugin \fIhttps://bundler\.io/guides/bundler_plugins\.html\fR
+.IP "" 0
+
diff --git a/lib/bundler/man/bundle-plugin.1.ronn b/lib/bundler/man/bundle-plugin.1.ronn
new file mode 100644
index 0000000000..b54e0c08b4
--- /dev/null
+++ b/lib/bundler/man/bundle-plugin.1.ronn
@@ -0,0 +1,84 @@
+bundle-plugin(1) -- Manage Bundler plugins
+==========================================
+
+## SYNOPSIS
+
+`bundle plugin` install PLUGINS [--source=SOURCE] [--version=VERSION]
+                              [--git=GIT] [--branch=BRANCH|--ref=REF]
+                              [--path=PATH]<br>
+`bundle plugin` uninstall PLUGINS [--all]<br>
+`bundle plugin` list<br>
+`bundle plugin` help [COMMAND]
+
+## DESCRIPTION
+
+You can install, uninstall, and list plugin(s) with this command to extend functionalities of Bundler.
+
+## SUB-COMMANDS
+
+### install
+
+Install the given plugin(s).
+
+For example, `bundle plugin install bundler-graph` will install bundler-graph
+gem from globally configured sources (defaults to RubyGems.org). Note that the
+global source specified in Gemfile is ignored.
+
+**OPTIONS**
+
+* `--source=SOURCE`:
+  Install the plugin gem from a specific source, rather than from globally configured sources.
+
+  Example: `bundle plugin install bundler-graph --source https://example.com`
+
+* `--version=VERSION`:
+  Specify a version of the plugin gem to install via `--version`.
+
+  Example: `bundle plugin install bundler-graph --version 0.2.1`
+
+* `--git=GIT`:
+  Install the plugin gem from a Git repository. You can use standard Git URLs like:
+
+  `ssh://[user@]host.xz[:port]/path/to/repo.git`<br>
+  `http[s]://host.xz[:port]/path/to/repo.git`<br>
+  `/path/to/repo`<br>
+  `file:///path/to/repo`
+
+  Example: `bundle plugin install bundler-graph --git https://github.com/rubygems/bundler-graph`
+
+* `--branch=BRANCH`:
+  When you specify `--git`, you can use `--branch`  to use.
+
+* `--ref=REF`:
+  When you specify `--git`, you can use `--ref` to specify any tag, or commit
+  hash (revision) to use.
+
+* `--path=PATH`:
+  Install the plugin gem from a local path.
+
+  Example: `bundle plugin install bundler-graph --path ../bundler-graph`
+
+### uninstall
+
+Uninstall the plugin(s) specified in PLUGINS.
+
+**OPTIONS**
+
+* `--all`:
+  Uninstall all the installed plugins. If no plugin is installed, then it does nothing.
+
+### list
+
+List the installed plugins and available commands.
+
+No options.
+
+### help
+
+Describe subcommands or one specific subcommand.
+
+No options.
+
+## SEE ALSO
+
+* [How to write a Bundler plugin](https://bundler.io/guides/bundler_plugins.html)
diff --git a/lib/bundler/man/bundle-pristine.1 b/lib/bundler/man/bundle-pristine.1
new file mode 100644
index 0000000000..f6cc066571
--- /dev/null
+++ b/lib/bundler/man/bundle-pristine.1
@@ -0,0 +1,23 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-PRISTINE" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-pristine\fR \- Restores installed gems to their pristine condition
+.SH "SYNOPSIS"
+\fBbundle pristine\fR
+.SH "DESCRIPTION"
+\fBpristine\fR restores the installed gems in the bundle to their pristine condition using the local gem cache from RubyGems\. For git gems, a forced checkout will be performed\.
+.P
+For further explanation, \fBbundle pristine\fR ignores unpacked files on disk\. In other words, this command utilizes the local \fB\.gem\fR cache or the gem's git repository as if one were installing from scratch\.
+.P
+Note: the Bundler gem cannot be restored to its original state with \fBpristine\fR\. One also cannot use \fBbundle pristine\fR on gems with a 'path' option in the Gemfile, because bundler has no original copy it can restore from\.
+.P
+When is it practical to use \fBbundle pristine\fR?
+.P
+It comes in handy when a developer is debugging a gem\. \fBbundle pristine\fR is a great way to get rid of experimental changes to a gem that one may not want\.
+.P
+Why use \fBbundle pristine\fR over \fBgem pristine \-\-all\fR?
+.P
+Both commands are very similar\. For context: \fBbundle pristine\fR, without arguments, cleans all gems from the lockfile\. Meanwhile, \fBgem pristine \-\-all\fR cleans all installed gems for that Ruby version\.
+.P
+If a developer forgets which gems in their project they might have been debugging, the Rubygems \fBgem pristine [GEMNAME]\fR command may be inconvenient\. One can avoid waiting for \fBgem pristine \-\-all\fR, and instead run \fBbundle pristine\fR\.
diff --git a/lib/bundler/man/bundle-pristine.1.ronn b/lib/bundler/man/bundle-pristine.1.ronn
new file mode 100644
index 0000000000..984debeb3d
--- /dev/null
+++ b/lib/bundler/man/bundle-pristine.1.ronn
@@ -0,0 +1,34 @@
+bundle-pristine(1) -- Restores installed gems to their pristine condition
+=========================================================================
+
+## SYNOPSIS
+
+`bundle pristine`
+
+## DESCRIPTION
+
+`pristine` restores the installed gems in the bundle to their pristine condition
+using the local gem cache from RubyGems. For git gems, a forced checkout will be performed.
+
+For further explanation, `bundle pristine` ignores unpacked files on disk. In other
+words, this command utilizes the local `.gem` cache or the gem's git repository
+as if one were installing from scratch.
+
+Note: the Bundler gem cannot be restored to its original state with `pristine`.
+One also cannot use `bundle pristine` on gems with a 'path' option in the Gemfile,
+because bundler has no original copy it can restore from.
+
+When is it practical to use `bundle pristine`?
+
+It comes in handy when a developer is debugging a gem. `bundle pristine` is a
+great way to get rid of experimental changes to a gem that one may not want.
+
+Why use `bundle pristine` over `gem pristine --all`?
+
+Both commands are very similar.
+For context: `bundle pristine`, without arguments, cleans all gems from the lockfile.
+Meanwhile, `gem pristine --all` cleans all installed gems for that Ruby version.
+
+If a developer forgets which gems in their project they might
+have been debugging, the Rubygems `gem pristine [GEMNAME]` command may be inconvenient.
+One can avoid waiting for `gem pristine --all`, and instead run `bundle pristine`.
diff --git a/lib/bundler/man/bundle-remove.1 b/lib/bundler/man/bundle-remove.1
new file mode 100644
index 0000000000..2ca40e74db
--- /dev/null
+++ b/lib/bundler/man/bundle-remove.1
@@ -0,0 +1,15 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-REMOVE" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-remove\fR \- Removes gems from the Gemfile
+.SH "SYNOPSIS"
+`bundle remove [GEM [GEM \|\.\|\.\|\.]]
+.SH "DESCRIPTION"
+Removes the given gems from the Gemfile while ensuring that the resulting Gemfile is still valid\. If a gem cannot be removed, a warning is printed\. If a gem is already absent from the Gemfile, and error is raised\.
+.P
+Example:
+.P
+bundle remove rails
+.P
+bundle remove rails rack
diff --git a/lib/bundler/man/bundle-remove.1.ronn b/lib/bundler/man/bundle-remove.1.ronn
new file mode 100644
index 0000000000..49cb4dc1fd
--- /dev/null
+++ b/lib/bundler/man/bundle-remove.1.ronn
@@ -0,0 +1,16 @@
+bundle-remove(1) -- Removes gems from the Gemfile
+=================================================
+
+## SYNOPSIS
+
+`bundle remove [GEM [GEM ...]]
+
+## DESCRIPTION
+
+Removes the given gems from the Gemfile while ensuring that the resulting Gemfile is still valid. If a gem cannot be removed, a warning is printed. If a gem is already absent from the Gemfile, and error is raised.
+
+Example:
+
+bundle remove rails
+
+bundle remove rails rack
diff --git a/lib/bundler/man/bundle-show.1 b/lib/bundler/man/bundle-show.1
new file mode 100644
index 0000000000..a2142694b8
--- /dev/null
+++ b/lib/bundler/man/bundle-show.1
@@ -0,0 +1,16 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-SHOW" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-show\fR \- Shows all the gems in your bundle, or the path to a gem
+.SH "SYNOPSIS"
+\fBbundle show\fR [GEM] [\-\-paths]
+.SH "DESCRIPTION"
+Without the [GEM] option, \fBshow\fR will print a list of the names and versions of all gems that are required by your [\fBGemfile(5)\fR][Gemfile(5)], sorted by name\.
+.P
+Calling show with [GEM] will list the exact location of that gem on your machine\.
+.SH "OPTIONS"
+.TP
+\fB\-\-paths\fR
+List the paths of all gems that are required by your [\fBGemfile(5)\fR][Gemfile(5)], sorted by gem name\.
+
diff --git a/lib/bundler/man/bundle-show.1.ronn b/lib/bundler/man/bundle-show.1.ronn
new file mode 100644
index 0000000000..a6a59a1445
--- /dev/null
+++ b/lib/bundler/man/bundle-show.1.ronn
@@ -0,0 +1,21 @@
+bundle-show(1) -- Shows all the gems in your bundle, or the path to a gem
+=========================================================================
+
+## SYNOPSIS
+
+`bundle show` [GEM]
+              [--paths]
+
+## DESCRIPTION
+
+Without the [GEM] option, `show` will print a list of the names and versions of
+all gems that are required by your [`Gemfile(5)`][Gemfile(5)], sorted by name.
+
+Calling show with [GEM] will list the exact location of that gem on your
+machine.
+
+## OPTIONS
+
+* `--paths`:
+  List the paths of all gems that are required by your [`Gemfile(5)`][Gemfile(5)],
+  sorted by gem name.
diff --git a/lib/bundler/man/bundle-update.1 b/lib/bundler/man/bundle-update.1
new file mode 100644
index 0000000000..94161083fc
--- /dev/null
+++ b/lib/bundler/man/bundle-update.1
@@ -0,0 +1,284 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-UPDATE" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-update\fR \- Update your gems to the latest available versions
+.SH "SYNOPSIS"
+\fBbundle update\fR \fI*gems\fR [\-\-all] [\-\-group=NAME] [\-\-source=NAME] [\-\-local] [\-\-ruby] [\-\-bundler[=VERSION]] [\-\-cooldown=NUMBER] [\-\-force] [\-\-full\-index] [\-\-gemfile=GEMFILE] [\-\-jobs=NUMBER] [\-\-quiet] [\-\-patch|\-\-minor|\-\-major] [\-\-pre] [\-\-strict] [\-\-conservative]
+.SH "DESCRIPTION"
+Update the gems specified (all gems, if \fB\-\-all\fR flag is used), ignoring the previously installed gems specified in the \fBGemfile\.lock\fR\. In general, you should use bundle install(1) \fIbundle\-install\.1\.html\fR to install the same exact gems and versions across machines\.
+.P
+You would use \fBbundle update\fR to explicitly update the version of a gem\.
+.SH "OPTIONS"
+.TP
+\fB\-\-all\fR
+Update all gems specified in Gemfile\.
+.TP
+\fB\-\-group=<list>\fR, \fB\-g=<list>\fR
+Only update the gems in the specified group\. For instance, you can update all gems in the development group with \fBbundle update \-\-group development\fR\. You can also call \fBbundle update rails \-\-group test\fR to update the rails gem and all gems in the test group, for example\.
+.TP
+\fB\-\-source=<list>\fR
+The name of a \fB:git\fR or \fB:path\fR source used in the Gemfile(5)\. For instance, with a \fB:git\fR source of \fBhttp://github\.com/rails/rails\.git\fR, you would call \fBbundle update \-\-source rails\fR
+.TP
+\fB\-\-local\fR
+Do not attempt to fetch gems remotely and use the gem cache instead\.
+.TP
+\fB\-\-ruby\fR
+Update the locked version of Ruby to the current version of Ruby\.
+.TP
+\fB\-\-bundler[=BUNDLER]\fR
+Update the locked version of bundler to the invoked bundler version\.
+.TP
+\fB\-\-force\fR, \fB\-\-redownload\fR
+Force reinstalling every gem, even if already installed\.
+.TP
+\fB\-\-full\-index\fR
+Fall back to using the single\-file index of all gems\.
+.TP
+\fB\-\-gemfile=GEMFILE\fR
+Use the specified gemfile instead of [\fBGemfile(5)\fR][Gemfile(5)]\.
+.TP
+\fB\-\-jobs=<number>\fR, \fB\-j=<number>\fR
+Specify the number of jobs to run in parallel\. The default is the number of available processors\.
+.TP
+\fB\-\-retry=[<number>]\fR
+Retry failed network or git requests for \fInumber\fR times\.
+.TP
+\fB\-\-quiet\fR
+Only output warnings and errors\.
+.TP
+\fB\-\-patch\fR
+Prefer updating only to next patch version\.
+.TP
+\fB\-\-minor\fR
+Prefer updating only to next minor version\.
+.TP
+\fB\-\-major\fR
+Prefer updating to next major version (default)\.
+.TP
+\fB\-\-pre\fR
+Always choose the highest allowed version, regardless of prerelease status\.
+.TP
+\fB\-\-strict\fR
+Do not allow any gem to be updated past latest \fB\-\-patch\fR | \fB\-\-minor\fR | \fB\-\-major\fR\.
+.TP
+\fB\-\-conservative\fR
+Use bundle install conservative update behavior and do not allow indirect dependencies to be updated\.
+.TP
+\fB\-\-cooldown=<number>\fR
+Only consider gem versions published at least \fInumber\fR days ago when resolving\. Pass \fB0\fR to disable cooldown for this run, overriding any per\-source or global configuration\. Combine with \fB\-\-conservative\fR to minimize transitive churn when bypassing cooldown for an urgent update\. See \fBcooldown\fR in bundle\-config(1)\.
+.SH "UPDATING ALL GEMS"
+If you run \fBbundle update \-\-all\fR, bundler will ignore any previously installed gems and resolve all dependencies again based on the latest versions of all gems available in the sources\.
+.P
+Consider the following Gemfile(5):
+.IP "" 4
+.nf
+source "https://rubygems\.org"
+
+gem "rails", "3\.0\.0\.rc"
+gem "nokogiri"
+.fi
+.IP "" 0
+.P
+When you run bundle install(1) \fIbundle\-install\.1\.html\fR the first time, bundler will resolve all of the dependencies, all the way down, and install what you need:
+.IP "" 4
+.nf
+Fetching gem metadata from https://rubygems\.org/\|\.\|\.\|\.\|\.\|\.\|\.\|\.\|\.\|\.
+Resolving dependencies\|\.\|\.\|\.
+Installing builder 2\.1\.2
+Installing abstract 1\.0\.0
+Installing rack 1\.2\.8
+Using bundler 1\.7\.6
+Installing rake 10\.4\.0
+Installing polyglot 0\.3\.5
+Installing mime\-types 1\.25\.1
+Installing i18n 0\.4\.2
+Installing mini_portile 0\.6\.1
+Installing tzinfo 0\.3\.42
+Installing rack\-mount 0\.6\.14
+Installing rack\-test 0\.5\.7
+Installing treetop 1\.4\.15
+Installing thor 0\.14\.6
+Installing activesupport 3\.0\.0\.rc
+Installing erubis 2\.6\.6
+Installing activemodel 3\.0\.0\.rc
+Installing arel 0\.4\.0
+Installing mail 2\.2\.20
+Installing activeresource 3\.0\.0\.rc
+Installing actionpack 3\.0\.0\.rc
+Installing activerecord 3\.0\.0\.rc
+Installing actionmailer 3\.0\.0\.rc
+Installing railties 3\.0\.0\.rc
+Installing rails 3\.0\.0\.rc
+Installing nokogiri 1\.6\.5
+
+Bundle complete! 2 Gemfile dependencies, 26 gems total\.
+Use `bundle show [gemname]` to see where a bundled gem is installed\.
+.fi
+.IP "" 0
+.P
+As you can see, even though you have two gems in the Gemfile(5), your application needs 26 different gems in order to run\. Bundler remembers the exact versions it installed in \fBGemfile\.lock\fR\. The next time you run bundle install(1) \fIbundle\-install\.1\.html\fR, bundler skips the dependency resolution and installs the same gems as it installed last time\.
+.P
+After checking in the \fBGemfile\.lock\fR into version control and cloning it on another machine, running bundle install(1) \fIbundle\-install\.1\.html\fR will \fIstill\fR install the gems that you installed last time\. You don't need to worry that a new release of \fBerubis\fR or \fBmail\fR changes the gems you use\.
+.P
+However, from time to time, you might want to update the gems you are using to the newest versions that still match the gems in your Gemfile(5)\.
+.P
+To do this, run \fBbundle update \-\-all\fR, which will ignore the \fBGemfile\.lock\fR, and resolve all the dependencies again\. Keep in mind that this process can result in a significantly different set of the 25 gems, based on the requirements of new gems that the gem authors released since the last time you ran \fBbundle update \-\-all\fR\.
+.SH "UPDATING A LIST OF GEMS"
+Sometimes, you want to update a single gem in the Gemfile(5), and leave the rest of the gems that you specified locked to the versions in the \fBGemfile\.lock\fR\.
+.P
+For instance, in the scenario above, imagine that \fBnokogiri\fR releases version \fB1\.4\.4\fR, and you want to update it \fIwithout\fR updating Rails and all of its dependencies\. To do this, run \fBbundle update nokogiri\fR\.
+.P
+Bundler will update \fBnokogiri\fR and any of its dependencies, but leave alone Rails and its dependencies\.
+.SH "OVERLAPPING DEPENDENCIES"
+Sometimes, multiple gems declared in your Gemfile(5) are satisfied by the same second\-level dependency\. For instance, consider the case of \fBthin\fR and \fBrack\-perftools\-profiler\fR\.
+.IP "" 4
+.nf
+source "https://rubygems\.org"
+
+gem "thin"
+gem "rack\-perftools\-profiler"
+.fi
+.IP "" 0
+.P
+The \fBthin\fR gem depends on \fBrack >= 1\.0\fR, while \fBrack\-perftools\-profiler\fR depends on \fBrack ~> 1\.0\fR\. If you run bundle install, you get:
+.IP "" 4
+.nf
+Fetching source index for https://rubygems\.org/
+Installing daemons (1\.1\.0)
+Installing eventmachine (0\.12\.10) with native extensions
+Installing open4 (1\.0\.1)
+Installing perftools\.rb (0\.4\.7) with native extensions
+Installing rack (1\.2\.1)
+Installing rack\-perftools_profiler (0\.0\.2)
+Installing thin (1\.2\.7) with native extensions
+Using bundler (1\.0\.0\.rc\.3)
+.fi
+.IP "" 0
+.P
+In this case, the two gems have their own set of dependencies, but they share \fBrack\fR in common\. If you run \fBbundle update thin\fR, bundler will update \fBdaemons\fR, \fBeventmachine\fR and \fBrack\fR, which are dependencies of \fBthin\fR, but not \fBopen4\fR or \fBperftools\.rb\fR, which are dependencies of \fBrack\-perftools_profiler\fR\. Note that \fBbundle update thin\fR will update \fBrack\fR even though it's \fIalso\fR a dependency of \fBrack\-perftools_profiler\fR\.
+.P
+In short, by default, when you update a gem using \fBbundle update\fR, bundler will update all dependencies of that gem, including those that are also dependencies of another gem\.
+.P
+To prevent updating indirect dependencies, prior to version 1\.14 the only option was the \fBCONSERVATIVE UPDATING\fR behavior in bundle install(1) \fIbundle\-install\.1\.html\fR:
+.P
+In this scenario, updating the \fBthin\fR version manually in the Gemfile(5), and then running bundle install(1) \fIbundle\-install\.1\.html\fR will only update \fBdaemons\fR and \fBeventmachine\fR, but not \fBrack\fR\. For more information, see the \fBCONSERVATIVE UPDATING\fR section of bundle install(1) \fIbundle\-install\.1\.html\fR\.
+.P
+Starting with 1\.14, specifying the \fB\-\-conservative\fR option will also prevent indirect dependencies from being updated\.
+.SH "PATCH LEVEL OPTIONS"
+Version 1\.14 introduced 4 patch\-level options that will influence how gem versions are resolved\. One of the following options can be used: \fB\-\-patch\fR, \fB\-\-minor\fR or \fB\-\-major\fR\. \fB\-\-strict\fR can be added to further influence resolution\.
+.TP
+\fB\-\-patch\fR
+Prefer updating only to next patch version\.
+.TP
+\fB\-\-minor\fR
+Prefer updating only to next minor version\.
+.TP
+\fB\-\-major\fR
+Prefer updating to next major version (default)\.
+.TP
+\fB\-\-strict\fR
+Do not allow any gem to be updated past latest \fB\-\-patch\fR | \fB\-\-minor\fR | \fB\-\-major\fR\.
+.P
+When Bundler is resolving what versions to use to satisfy declared requirements in the Gemfile or in parent gems, it looks up all available versions, filters out any versions that don't satisfy the requirement, and then, by default, sorts them from newest to oldest, considering them in that order\.
+.P
+Providing one of the patch level options (e\.g\. \fB\-\-patch\fR) changes the sort order of the satisfying versions, causing Bundler to consider the latest \fB\-\-patch\fR or \fB\-\-minor\fR version available before other versions\. Note that versions outside the stated patch level could still be resolved to if necessary to find a suitable dependency graph\.
+.P
+For example, if gem 'foo' is locked at 1\.0\.2, with no gem requirement defined in the Gemfile, and versions 1\.0\.3, 1\.0\.4, 1\.1\.0, 1\.1\.1, 2\.0\.0 all exist, the default order of preference by default (\fB\-\-major\fR) will be "2\.0\.0, 1\.1\.1, 1\.1\.0, 1\.0\.4, 1\.0\.3, 1\.0\.2"\.
+.P
+If the \fB\-\-patch\fR option is used, the order of preference will change to "1\.0\.4, 1\.0\.3, 1\.0\.2, 1\.1\.1, 1\.1\.0, 2\.0\.0"\.
+.P
+If the \fB\-\-minor\fR option is used, the order of preference will change to "1\.1\.1, 1\.1\.0, 1\.0\.4, 1\.0\.3, 1\.0\.2, 2\.0\.0"\.
+.P
+Combining the \fB\-\-strict\fR option with any of the patch level options will remove any versions beyond the scope of the patch level option, to ensure that no gem is updated that far\.
+.P
+To continue the previous example, if both \fB\-\-patch\fR and \fB\-\-strict\fR options are used, the available versions for resolution would be "1\.0\.4, 1\.0\.3, 1\.0\.2"\. If \fB\-\-minor\fR and \fB\-\-strict\fR are used, it would be "1\.1\.1, 1\.1\.0, 1\.0\.4, 1\.0\.3, 1\.0\.2"\.
+.P
+Gem requirements as defined in the Gemfile will still be the first determining factor for what versions are available\. If the gem requirement for \fBfoo\fR in the Gemfile is '~> 1\.0', that will accomplish the same thing as providing the \fB\-\-minor\fR and \fB\-\-strict\fR options\.
+.SH "PATCH LEVEL EXAMPLES"
+Given the following gem specifications:
+.IP "" 4
+.nf
+foo 1\.4\.3, requires: ~> bar 2\.0
+foo 1\.4\.4, requires: ~> bar 2\.0
+foo 1\.4\.5, requires: ~> bar 2\.1
+foo 1\.5\.0, requires: ~> bar 2\.1
+foo 1\.5\.1, requires: ~> bar 3\.0
+bar with versions 2\.0\.3, 2\.0\.4, 2\.1\.0, 2\.1\.1, 3\.0\.0
+.fi
+.IP "" 0
+.P
+Gemfile:
+.IP "" 4
+.nf
+gem 'foo'
+.fi
+.IP "" 0
+.P
+Gemfile\.lock:
+.IP "" 4
+.nf
+foo (1\.4\.3)
+  bar (~> 2\.0)
+bar (2\.0\.3)
+.fi
+.IP "" 0
+.P
+Cases:
+.IP "" 4
+.nf
+#  Command Line                     Result
+\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
+1  bundle update \-\-patch            'foo 1\.4\.5', 'bar 2\.1\.1'
+2  bundle update \-\-patch foo        'foo 1\.4\.5', 'bar 2\.1\.1'
+3  bundle update \-\-minor            'foo 1\.5\.1', 'bar 3\.0\.0'
+4  bundle update \-\-minor \-\-strict   'foo 1\.5\.0', 'bar 2\.1\.1'
+5  bundle update \-\-patch \-\-strict   'foo 1\.4\.4', 'bar 2\.0\.4'
+.fi
+.IP "" 0
+.P
+In case 1, bar is upgraded to 2\.1\.1, a minor version increase, because the dependency from foo 1\.4\.5 required it\.
+.P
+In case 2, only foo is requested to be unlocked, but bar is also allowed to move because it's not a declared dependency in the Gemfile\.
+.P
+In case 3, bar goes up a whole major release, because a minor increase is preferred now for foo, and when it goes to 1\.5\.1, it requires 3\.0\.0 of bar\.
+.P
+In case 4, foo is preferred up to a minor version, but 1\.5\.1 won't work because the \-\-strict flag removes bar 3\.0\.0 from consideration since it's a major increment\.
+.P
+In case 5, both foo and bar have any minor or major increments removed from consideration because of the \-\-strict flag, so the most they can move is up to 1\.4\.4 and 2\.0\.4\.
+.SH "RECOMMENDED WORKFLOW"
+In general, when working with an application managed with bundler, you should use the following workflow:
+.IP "\(bu" 4
+After you create your Gemfile(5) for the first time, run
+.IP
+$ bundle install
+.IP "\(bu" 4
+Check the resulting \fBGemfile\.lock\fR into version control
+.IP
+$ git add Gemfile\.lock
+.IP "\(bu" 4
+When checking out this repository on another development machine, run
+.IP
+$ bundle install
+.IP "\(bu" 4
+When checking out this repository on a deployment machine, run
+.IP
+$ bundle install \-\-deployment
+.IP "\(bu" 4
+After changing the Gemfile(5) to reflect a new or update dependency, run
+.IP
+$ bundle install
+.IP "\(bu" 4
+Make sure to check the updated \fBGemfile\.lock\fR into version control
+.IP
+$ git add Gemfile\.lock
+.IP "\(bu" 4
+If bundle install(1) \fIbundle\-install\.1\.html\fR reports a conflict, manually update the specific gems that you changed in the Gemfile(5)
+.IP
+$ bundle update rails thin
+.IP "\(bu" 4
+If you want to update all the gems to the latest possible versions that still match the gems listed in the Gemfile(5), run
+.IP
+$ bundle update \-\-all
+.IP "" 0
+
diff --git a/lib/bundler/man/bundle-update.1.ronn b/lib/bundler/man/bundle-update.1.ronn
new file mode 100644
index 0000000000..72fbf054d1
--- /dev/null
+++ b/lib/bundler/man/bundle-update.1.ronn
@@ -0,0 +1,367 @@
+bundle-update(1) -- Update your gems to the latest available versions
+=====================================================================
+
+## SYNOPSIS
+
+`bundle update` <*gems> [--all]
+                        [--group=NAME]
+                        [--source=NAME]
+                        [--local]
+                        [--ruby]
+                        [--bundler[=VERSION]]
+                        [--cooldown=NUMBER]
+                        [--force]
+                        [--full-index]
+                        [--gemfile=GEMFILE]
+                        [--jobs=NUMBER]
+                        [--quiet]
+                        [--patch|--minor|--major]
+                        [--pre]
+                        [--strict]
+                        [--conservative]
+
+## DESCRIPTION
+
+Update the gems specified (all gems, if `--all` flag is used), ignoring
+the previously installed gems specified in the `Gemfile.lock`. In
+general, you should use [bundle install(1)](bundle-install.1.html) to install the same exact
+gems and versions across machines.
+
+You would use `bundle update` to explicitly update the version of a
+gem.
+
+## OPTIONS
+
+* `--all`:
+  Update all gems specified in Gemfile.
+
+* `--group=<list>`, `-g=<list>`:
+  Only update the gems in the specified group. For instance, you can update all gems
+  in the development group with `bundle update --group development`. You can also
+  call `bundle update rails --group test` to update the rails gem and all gems in
+  the test group, for example.
+
+* `--source=<list>`:
+  The name of a `:git` or `:path` source used in the Gemfile(5). For
+  instance, with a `:git` source of `http://github.com/rails/rails.git`,
+  you would call `bundle update --source rails`
+
+* `--local`:
+  Do not attempt to fetch gems remotely and use the gem cache instead.
+
+* `--ruby`:
+  Update the locked version of Ruby to the current version of Ruby.
+
+* `--bundler[=BUNDLER]`:
+  Update the locked version of bundler to the invoked bundler version.
+
+* `--force`, `--redownload`:
+  Force reinstalling every gem, even if already installed.
+
+* `--full-index`:
+  Fall back to using the single-file index of all gems.
+
+* `--gemfile=GEMFILE`:
+  Use the specified gemfile instead of [`Gemfile(5)`][Gemfile(5)].
+
+* `--jobs=<number>`, `-j=<number>`:
+  Specify the number of jobs to run in parallel. The default is the number of
+  available processors.
+
+* `--retry=[<number>]`:
+  Retry failed network or git requests for <number> times.
+
+* `--quiet`:
+  Only output warnings and errors.
+
+* `--patch`:
+  Prefer updating only to next patch version.
+
+* `--minor`:
+  Prefer updating only to next minor version.
+
+* `--major`:
+  Prefer updating to next major version (default).
+
+* `--pre`:
+  Always choose the highest allowed version, regardless of prerelease status.
+
+* `--strict`:
+  Do not allow any gem to be updated past latest `--patch` | `--minor` | `--major`.
+
+* `--conservative`:
+  Use bundle install conservative update behavior and do not allow indirect dependencies to be updated.
+
+* `--cooldown=<number>`:
+  Only consider gem versions published at least <number> days ago when
+  resolving. Pass `0` to disable cooldown for this run, overriding any
+  per-source or global configuration. Combine with `--conservative` to
+  minimize transitive churn when bypassing cooldown for an urgent
+  update. See `cooldown` in bundle-config(1).
+
+## UPDATING ALL GEMS
+
+If you run `bundle update --all`, bundler will ignore
+any previously installed gems and resolve all dependencies again
+based on the latest versions of all gems available in the sources.
+
+Consider the following Gemfile(5):
+
+    source "https://rubygems.org"
+
+    gem "rails", "3.0.0.rc"
+    gem "nokogiri"
+
+When you run [bundle install(1)](bundle-install.1.html) the first time, bundler will resolve
+all of the dependencies, all the way down, and install what you need:
+
+    Fetching gem metadata from https://rubygems.org/.........
+    Resolving dependencies...
+    Installing builder 2.1.2
+    Installing abstract 1.0.0
+    Installing rack 1.2.8
+    Using bundler 1.7.6
+    Installing rake 10.4.0
+    Installing polyglot 0.3.5
+    Installing mime-types 1.25.1
+    Installing i18n 0.4.2
+    Installing mini_portile 0.6.1
+    Installing tzinfo 0.3.42
+    Installing rack-mount 0.6.14
+    Installing rack-test 0.5.7
+    Installing treetop 1.4.15
+    Installing thor 0.14.6
+    Installing activesupport 3.0.0.rc
+    Installing erubis 2.6.6
+    Installing activemodel 3.0.0.rc
+    Installing arel 0.4.0
+    Installing mail 2.2.20
+    Installing activeresource 3.0.0.rc
+    Installing actionpack 3.0.0.rc
+    Installing activerecord 3.0.0.rc
+    Installing actionmailer 3.0.0.rc
+    Installing railties 3.0.0.rc
+    Installing rails 3.0.0.rc
+    Installing nokogiri 1.6.5
+
+    Bundle complete! 2 Gemfile dependencies, 26 gems total.
+    Use `bundle show [gemname]` to see where a bundled gem is installed.
+
+As you can see, even though you have two gems in the Gemfile(5), your application
+needs 26 different gems in order to run. Bundler remembers the exact versions
+it installed in `Gemfile.lock`. The next time you run [bundle install(1)](bundle-install.1.html), bundler skips
+the dependency resolution and installs the same gems as it installed last time.
+
+After checking in the `Gemfile.lock` into version control and cloning it on another
+machine, running [bundle install(1)](bundle-install.1.html) will _still_ install the gems that you installed
+last time. You don't need to worry that a new release of `erubis` or `mail` changes
+the gems you use.
+
+However, from time to time, you might want to update the gems you are using to the
+newest versions that still match the gems in your Gemfile(5).
+
+To do this, run `bundle update --all`, which will ignore the `Gemfile.lock`, and resolve
+all the dependencies again. Keep in mind that this process can result in a significantly
+different set of the 25 gems, based on the requirements of new gems that the gem
+authors released since the last time you ran `bundle update --all`.
+
+## UPDATING A LIST OF GEMS
+
+Sometimes, you want to update a single gem in the Gemfile(5), and leave the rest of the
+gems that you specified locked to the versions in the `Gemfile.lock`.
+
+For instance, in the scenario above, imagine that `nokogiri` releases version `1.4.4`, and
+you want to update it _without_ updating Rails and all of its dependencies. To do this,
+run `bundle update nokogiri`.
+
+Bundler will update `nokogiri` and any of its dependencies, but leave alone Rails and
+its dependencies.
+
+## OVERLAPPING DEPENDENCIES
+
+Sometimes, multiple gems declared in your Gemfile(5) are satisfied by the same
+second-level dependency. For instance, consider the case of `thin` and
+`rack-perftools-profiler`.
+
+    source "https://rubygems.org"
+
+    gem "thin"
+    gem "rack-perftools-profiler"
+
+The `thin` gem depends on `rack >= 1.0`, while `rack-perftools-profiler` depends
+on `rack ~> 1.0`. If you run bundle install, you get:
+
+    Fetching source index for https://rubygems.org/
+    Installing daemons (1.1.0)
+    Installing eventmachine (0.12.10) with native extensions
+    Installing open4 (1.0.1)
+    Installing perftools.rb (0.4.7) with native extensions
+    Installing rack (1.2.1)
+    Installing rack-perftools_profiler (0.0.2)
+    Installing thin (1.2.7) with native extensions
+    Using bundler (1.0.0.rc.3)
+
+In this case, the two gems have their own set of dependencies, but they share
+`rack` in common. If you run `bundle update thin`, bundler will update `daemons`,
+`eventmachine` and `rack`, which are dependencies of `thin`, but not `open4` or
+`perftools.rb`, which are dependencies of `rack-perftools_profiler`. Note that
+`bundle update thin` will update `rack` even though it's _also_ a dependency of
+`rack-perftools_profiler`.
+
+In short, by default, when you update a gem using `bundle update`, bundler will
+update all dependencies of that gem, including those that are also dependencies
+of another gem.
+
+To prevent updating indirect dependencies, prior to version 1.14 the only option
+was the `CONSERVATIVE UPDATING` behavior in [bundle install(1)](bundle-install.1.html):
+
+In this scenario, updating the `thin` version manually in the Gemfile(5),
+and then running [bundle install(1)](bundle-install.1.html) will only update `daemons` and `eventmachine`,
+but not `rack`. For more information, see the `CONSERVATIVE UPDATING` section
+of [bundle install(1)](bundle-install.1.html).
+
+Starting with 1.14, specifying the `--conservative` option will also prevent indirect
+dependencies from being updated.
+
+## PATCH LEVEL OPTIONS
+
+Version 1.14 introduced 4 patch-level options that will influence how gem
+versions are resolved. One of the following options can be used: `--patch`,
+`--minor` or `--major`. `--strict` can be added to further influence resolution.
+
+* `--patch`:
+  Prefer updating only to next patch version.
+
+* `--minor`:
+  Prefer updating only to next minor version.
+
+* `--major`:
+  Prefer updating to next major version (default).
+
+* `--strict`:
+  Do not allow any gem to be updated past latest `--patch` | `--minor` | `--major`.
+
+When Bundler is resolving what versions to use to satisfy declared
+requirements in the Gemfile or in parent gems, it looks up all
+available versions, filters out any versions that don't satisfy
+the requirement, and then, by default, sorts them from newest to
+oldest, considering them in that order.
+
+Providing one of the patch level options (e.g. `--patch`) changes the
+sort order of the satisfying versions, causing Bundler to consider the
+latest `--patch` or `--minor` version available before other versions.
+Note that versions outside the stated patch level could still be
+resolved to if necessary to find a suitable dependency graph.
+
+For example, if gem 'foo' is locked at 1.0.2, with no gem requirement
+defined in the Gemfile, and versions 1.0.3, 1.0.4, 1.1.0, 1.1.1, 2.0.0
+all exist, the default order of preference by default (`--major`) will
+be "2.0.0, 1.1.1, 1.1.0, 1.0.4, 1.0.3, 1.0.2".
+
+If the `--patch` option is used, the order of preference will change to
+"1.0.4, 1.0.3, 1.0.2, 1.1.1, 1.1.0, 2.0.0".
+
+If the `--minor` option is used, the order of preference will change to
+"1.1.1, 1.1.0, 1.0.4, 1.0.3, 1.0.2, 2.0.0".
+
+Combining the `--strict` option with any of the patch level options
+will remove any versions beyond the scope of the patch level option,
+to ensure that no gem is updated that far.
+
+To continue the previous example, if both `--patch` and `--strict`
+options are used, the available versions for resolution would be
+"1.0.4, 1.0.3, 1.0.2". If `--minor` and `--strict` are used, it would
+be "1.1.1, 1.1.0, 1.0.4, 1.0.3, 1.0.2".
+
+Gem requirements as defined in the Gemfile will still be the first
+determining factor for what versions are available. If the gem
+requirement for `foo` in the Gemfile is '~> 1.0', that will accomplish
+the same thing as providing the `--minor` and `--strict` options.
+
+## PATCH LEVEL EXAMPLES
+
+Given the following gem specifications:
+
+    foo 1.4.3, requires: ~> bar 2.0
+    foo 1.4.4, requires: ~> bar 2.0
+    foo 1.4.5, requires: ~> bar 2.1
+    foo 1.5.0, requires: ~> bar 2.1
+    foo 1.5.1, requires: ~> bar 3.0
+    bar with versions 2.0.3, 2.0.4, 2.1.0, 2.1.1, 3.0.0
+
+Gemfile:
+
+    gem 'foo'
+
+Gemfile.lock:
+
+    foo (1.4.3)
+      bar (~> 2.0)
+    bar (2.0.3)
+
+Cases:
+
+    #  Command Line                     Result
+    ------------------------------------------------------------
+    1  bundle update --patch            'foo 1.4.5', 'bar 2.1.1'
+    2  bundle update --patch foo        'foo 1.4.5', 'bar 2.1.1'
+    3  bundle update --minor            'foo 1.5.1', 'bar 3.0.0'
+    4  bundle update --minor --strict   'foo 1.5.0', 'bar 2.1.1'
+    5  bundle update --patch --strict   'foo 1.4.4', 'bar 2.0.4'
+
+In case 1, bar is upgraded to 2.1.1, a minor version increase, because
+the dependency from foo 1.4.5 required it.
+
+In case 2, only foo is requested to be unlocked, but bar is also
+allowed to move because it's not a declared dependency in the Gemfile.
+
+In case 3, bar goes up a whole major release, because a minor increase
+is preferred now for foo, and when it goes to 1.5.1, it requires 3.0.0
+of bar.
+
+In case 4, foo is preferred up to a minor version, but 1.5.1 won't work
+because the --strict flag removes bar 3.0.0 from consideration since
+it's a major increment.
+
+In case 5, both foo and bar have any minor or major increments removed
+from consideration because of the --strict flag, so the most they can
+move is up to 1.4.4 and 2.0.4.
+
+## RECOMMENDED WORKFLOW
+
+In general, when working with an application managed with bundler, you should
+use the following workflow:
+
+* After you create your Gemfile(5) for the first time, run
+
+    $ bundle install
+
+* Check the resulting `Gemfile.lock` into version control
+
+    $ git add Gemfile.lock
+
+* When checking out this repository on another development machine, run
+
+    $ bundle install
+
+* When checking out this repository on a deployment machine, run
+
+    $ bundle install --deployment
+
+* After changing the Gemfile(5) to reflect a new or update dependency, run
+
+    $ bundle install
+
+* Make sure to check the updated `Gemfile.lock` into version control
+
+    $ git add Gemfile.lock
+
+* If [bundle install(1)](bundle-install.1.html) reports a conflict, manually update the specific
+  gems that you changed in the Gemfile(5)
+
+    $ bundle update rails thin
+
+* If you want to update all the gems to the latest possible versions that
+  still match the gems listed in the Gemfile(5), run
+
+    $ bundle update --all
diff --git a/lib/bundler/man/bundle-version.1 b/lib/bundler/man/bundle-version.1
new file mode 100644
index 0000000000..751a408312
--- /dev/null
+++ b/lib/bundler/man/bundle-version.1
@@ -0,0 +1,22 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE\-VERSION" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\-version\fR \- Prints Bundler version information
+.SH "SYNOPSIS"
+\fBbundle version\fR
+.SH "DESCRIPTION"
+Prints Bundler version information\.
+.SH "OPTIONS"
+No options\.
+.SH "EXAMPLE"
+Print the version of Bundler with build date and commit hash of the in the Git source\.
+.IP "" 4
+.nf
+bundle version
+.fi
+.IP "" 0
+.P
+shows \fBBundler version 2\.3\.21 (2022\-08\-24 commit d54be5fdd8)\fR for example\.
+.P
+cf\. \fBbundle \-\-version\fR shows \fBBundler version 2\.3\.21\fR\.
diff --git a/lib/bundler/man/bundle-version.1.ronn b/lib/bundler/man/bundle-version.1.ronn
new file mode 100644
index 0000000000..46c6f0b30a
--- /dev/null
+++ b/lib/bundler/man/bundle-version.1.ronn
@@ -0,0 +1,24 @@
+bundle-version(1) -- Prints Bundler version information
+=======================================================
+
+## SYNOPSIS
+
+`bundle version`
+
+## DESCRIPTION
+
+Prints Bundler version information.
+
+## OPTIONS
+
+No options.
+
+## EXAMPLE
+
+Print the version of Bundler with build date and commit hash of the in the Git source.
+
+    bundle version
+
+shows `Bundler version 2.3.21 (2022-08-24 commit d54be5fdd8)` for example.
+
+cf. `bundle --version` shows `Bundler version 2.3.21`.
diff --git a/lib/bundler/man/bundle.1 b/lib/bundler/man/bundle.1
new file mode 100644
index 0000000000..167815631a
--- /dev/null
+++ b/lib/bundler/man/bundle.1
@@ -0,0 +1,93 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "BUNDLE" "1" "May 2026" ""
+.SH "NAME"
+\fBbundle\fR \- Ruby Dependency Management
+.SH "SYNOPSIS"
+\fBbundle\fR COMMAND [\-\-no\-color] [\-\-verbose] [ARGS]
+.SH "DESCRIPTION"
+Bundler manages an \fBapplication's dependencies\fR through its entire life across many machines systematically and repeatably\.
+.P
+See the bundler website \fIhttps://bundler\.io\fR for information on getting started, and Gemfile(5) for more information on the \fBGemfile\fR format\.
+.SH "OPTIONS"
+.TP
+\fB\-\-no\-color\fR
+Print all output without color
+.TP
+\fB\-\-retry\fR, \fB\-r\fR
+Specify the number of times you wish to attempt network commands
+.TP
+\fB\-\-verbose\fR, \fB\-V\fR
+Print out additional logging information
+.SH "BUNDLE COMMANDS"
+We divide \fBbundle\fR subcommands into primary commands and utilities:
+.SH "PRIMARY COMMANDS"
+.TP
+\fBbundle install(1)\fR \fIbundle\-install\.1\.html\fR
+Install the gems specified by the \fBGemfile\fR or \fBGemfile\.lock\fR
+.TP
+\fBbundle update(1)\fR \fIbundle\-update\.1\.html\fR
+Update dependencies to their latest versions
+.TP
+\fBbundle cache(1)\fR \fIbundle\-cache\.1\.html\fR
+Package the \.gem files required by your application into the \fBvendor/cache\fR directory (aliases: \fBbundle package\fR, \fBbundle pack\fR)
+.TP
+\fBbundle exec(1)\fR \fIbundle\-exec\.1\.html\fR
+Execute a script in the current bundle
+.TP
+\fBbundle config(1)\fR \fIbundle\-config\.1\.html\fR
+Specify and read configuration options for Bundler
+.TP
+\fBbundle help(1)\fR \fIbundle\-help\.1\.html\fR
+Display detailed help for each subcommand
+.SH "UTILITIES"
+.TP
+\fBbundle add(1)\fR \fIbundle\-add\.1\.html\fR
+Add the named gem to the Gemfile and run \fBbundle install\fR
+.TP
+\fBbundle binstubs(1)\fR \fIbundle\-binstubs\.1\.html\fR
+Generate binstubs for executables in a gem
+.TP
+\fBbundle check(1)\fR \fIbundle\-check\.1\.html\fR
+Determine whether the requirements for your application are installed and available to Bundler
+.TP
+\fBbundle show(1)\fR \fIbundle\-show\.1\.html\fR
+Show the source location of a particular gem in the bundle
+.TP
+\fBbundle outdated(1)\fR \fIbundle\-outdated\.1\.html\fR
+Show all of the outdated gems in the current bundle
+.TP
+\fBbundle console(1)\fR (deprecated)
+Start an IRB session in the current bundle
+.TP
+\fBbundle open(1)\fR \fIbundle\-open\.1\.html\fR
+Open an installed gem in the editor
+.TP
+\fBbundle lock(1)\fR \fIbundle\-lock\.1\.html\fR
+Generate a lockfile for your dependencies
+.TP
+\fBbundle init(1)\fR \fIbundle\-init\.1\.html\fR
+Generate a simple \fBGemfile\fR, placed in the current directory
+.TP
+\fBbundle gem(1)\fR \fIbundle\-gem\.1\.html\fR
+Create a simple gem, suitable for development with Bundler
+.TP
+\fBbundle platform(1)\fR \fIbundle\-platform\.1\.html\fR
+Display platform compatibility information
+.TP
+\fBbundle clean(1)\fR \fIbundle\-clean\.1\.html\fR
+Clean up unused gems in your Bundler directory
+.TP
+\fBbundle doctor(1)\fR \fIbundle\-doctor\.1\.html\fR
+Display warnings about common problems
+.TP
+\fBbundle remove(1)\fR \fIbundle\-remove\.1\.html\fR
+Removes gems from the Gemfile
+.TP
+\fBbundle plugin(1)\fR \fIbundle\-plugin\.1\.html\fR
+Manage Bundler plugins
+.TP
+\fBbundle version(1)\fR \fIbundle\-version\.1\.html\fR
+Prints Bundler version information
+.SH "PLUGINS"
+When running a command that isn't listed in PRIMARY COMMANDS or UTILITIES, Bundler will try to find an executable on your path named \fBbundler\-<command>\fR and execute it, passing down any extra arguments to it\.
diff --git a/lib/bundler/man/bundle.1.ronn b/lib/bundler/man/bundle.1.ronn
new file mode 100644
index 0000000000..1c2b3df7af
--- /dev/null
+++ b/lib/bundler/man/bundle.1.ronn
@@ -0,0 +1,107 @@
+bundle(1) -- Ruby Dependency Management
+=======================================
+
+## SYNOPSIS
+
+`bundle` COMMAND [--no-color] [--verbose] [ARGS]
+
+## DESCRIPTION
+
+Bundler manages an `application's dependencies` through its entire life
+across many machines systematically and repeatably.
+
+See [the bundler website](https://bundler.io) for information on getting
+started, and Gemfile(5) for more information on the `Gemfile` format.
+
+## OPTIONS
+
+* `--no-color`:
+  Print all output without color
+
+* `--retry`, `-r`:
+  Specify the number of times you wish to attempt network commands
+
+* `--verbose`, `-V`:
+  Print out additional logging information
+
+## BUNDLE COMMANDS
+
+We divide `bundle` subcommands into primary commands and utilities:
+
+## PRIMARY COMMANDS
+
+* [`bundle install(1)`](bundle-install.1.html):
+  Install the gems specified by the `Gemfile` or `Gemfile.lock`
+
+* [`bundle update(1)`](bundle-update.1.html):
+  Update dependencies to their latest versions
+
+* [`bundle cache(1)`](bundle-cache.1.html):
+  Package the .gem files required by your application into the
+  `vendor/cache` directory (aliases: `bundle package`, `bundle pack`)
+
+* [`bundle exec(1)`](bundle-exec.1.html):
+  Execute a script in the current bundle
+
+* [`bundle config(1)`](bundle-config.1.html):
+  Specify and read configuration options for Bundler
+
+* [`bundle help(1)`](bundle-help.1.html):
+  Display detailed help for each subcommand
+
+## UTILITIES
+
+* [`bundle add(1)`](bundle-add.1.html):
+  Add the named gem to the Gemfile and run `bundle install`
+
+* [`bundle binstubs(1)`](bundle-binstubs.1.html):
+  Generate binstubs for executables in a gem
+
+* [`bundle check(1)`](bundle-check.1.html):
+  Determine whether the requirements for your application are installed
+  and available to Bundler
+
+* [`bundle show(1)`](bundle-show.1.html):
+  Show the source location of a particular gem in the bundle
+
+* [`bundle outdated(1)`](bundle-outdated.1.html):
+  Show all of the outdated gems in the current bundle
+
+* `bundle console(1)` (deprecated):
+  Start an IRB session in the current bundle
+
+* [`bundle open(1)`](bundle-open.1.html):
+  Open an installed gem in the editor
+
+* [`bundle lock(1)`](bundle-lock.1.html):
+  Generate a lockfile for your dependencies
+
+* [`bundle init(1)`](bundle-init.1.html):
+  Generate a simple `Gemfile`, placed in the current directory
+
+* [`bundle gem(1)`](bundle-gem.1.html):
+  Create a simple gem, suitable for development with Bundler
+
+* [`bundle platform(1)`](bundle-platform.1.html):
+  Display platform compatibility information
+
+* [`bundle clean(1)`](bundle-clean.1.html):
+  Clean up unused gems in your Bundler directory
+
+* [`bundle doctor(1)`](bundle-doctor.1.html):
+  Display warnings about common problems
+
+* [`bundle remove(1)`](bundle-remove.1.html):
+  Removes gems from the Gemfile
+
+* [`bundle plugin(1)`](bundle-plugin.1.html):
+  Manage Bundler plugins
+
+* [`bundle version(1)`](bundle-version.1.html):
+  Prints Bundler version information
+
+## PLUGINS
+
+When running a command that isn't listed in PRIMARY COMMANDS or UTILITIES,
+Bundler will try to find an executable on your path named `bundler-<command>`
+and execute it, passing down any extra arguments to it.
diff --git a/lib/bundler/man/gemfile.5 b/lib/bundler/man/gemfile.5
new file mode 100644
index 0000000000..64e93c4b15
--- /dev/null
+++ b/lib/bundler/man/gemfile.5
@@ -0,0 +1,547 @@
+.\" generated with Ronn-NG/v0.10.1
+.\" http://github.com/apjanke/ronn-ng/tree/0.10.1
+.TH "GEMFILE" "5" "May 2026" ""
+.SH "NAME"
+\fBGemfile\fR \- A format for describing gem dependencies for Ruby programs
+.SH "SYNOPSIS"
+A \fBGemfile\fR describes the gem dependencies required to execute associated Ruby code\.
+.P
+Place the \fBGemfile\fR in the root of the directory containing the associated code\. For instance, in a Rails application, place the \fBGemfile\fR in the same directory as the \fBRakefile\fR\.
+.SH "SYNTAX"
+A \fBGemfile\fR is evaluated as Ruby code, in a context which makes available a number of methods used to describe the gem requirements\.
+.SH "GLOBAL SOURCE"
+At the top of the \fBGemfile\fR, add a single line for the \fBRubyGems\fR source that contains the gems listed in the \fBGemfile\fR\.
+.IP "" 4
+.nf
+source "https://rubygems\.org"
+.fi
+.IP "" 0
+.P
+You can add only one global source\. In Bundler 1\.13, adding multiple global sources was deprecated\. The \fBsource\fR \fBMUST\fR be a valid RubyGems repository\.
+.P
+To use more than one source of RubyGems, you should use \fI\fBsource\fR block\fR\.
+.P
+A source is checked for gems following the heuristics described in \fISOURCE PRIORITY\fR\.
+.P
+\fBNote about a behavior of the feature deprecated in Bundler 1\.13\fR: If a gem is found in more than one global source, Bundler will print a warning after installing the gem indicating which source was used, and listing the other sources where the gem is available\. A specific source can be selected for gems that need to use a non\-standard repository, suppressing this warning, by using the \fI\fB:source\fR option\fR or \fBsource\fR block\.
+.SS "CREDENTIALS"
+Some gem sources require a username and password\. Use bundle config(1) \fIbundle\-config\.1\.html\fR to set the username and password for any of the sources that need it\. The command must be run once on each computer that will install the Gemfile, but this keeps the credentials from being stored in plain text in version control\.
+.IP "" 4
+.nf
+bundle config gems\.example\.com user:password
+.fi
+.IP "" 0
+.P
+For some sources, like a company Gemfury account, it may be easier to include the credentials in the Gemfile as part of the source URL\.
+.IP "" 4
+.nf
+source "https://user:password@gems\.example\.com"
+.fi
+.IP "" 0
+.P
+Credentials in the source URL will take precedence over credentials set using \fBconfig\fR\.
+.SH "RUBY"
+If your application requires a specific Ruby version or engine, specify your requirements using the \fBruby\fR method, with the following arguments\. All parameters are \fBOPTIONAL\fR unless otherwise specified\.
+.SS "VERSION (required)"
+The version of Ruby that your application requires\. If your application requires an alternate Ruby engine, such as JRuby, TruffleRuby, etc\., this should be the Ruby version that the engine is compatible with\.
+.IP "" 4
+.nf
+ruby "3\.1\.2"
+.fi
+.IP "" 0
+.P
+If you wish to derive your Ruby version from a version file (ie \.ruby\-version), you can use the \fBfile\fR option instead\.
+.IP "" 4
+.nf
+ruby file: "\.ruby\-version"
+.fi
+.IP "" 0
+.P
+The version file should conform to any of the following formats:
+.IP "\(bu" 4
+\fB3\.1\.2\fR (\.ruby\-version)
+.IP "\(bu" 4
+\fBruby 3\.1\.2\fR (\.tool\-versions, read: https://asdf\-vm\.com/manage/configuration\.html#tool\-versions)
+.IP "" 0
+.SS "ENGINE"
+Each application \fImay\fR specify a Ruby engine\. If an engine is specified, an engine version \fImust\fR also be specified\.
+.P
+What exactly is an Engine?
+.IP "\(bu" 4
+A Ruby engine is an implementation of the Ruby language\.
+.IP "\(bu" 4
+For background: the reference or original implementation of the Ruby programming language is called Matz's Ruby Interpreter \fIhttps://en\.wikipedia\.org/wiki/Ruby_MRI\fR, or MRI for short\. This is named after Ruby creator Yukihiro Matsumoto, also known as Matz\. MRI is also known as CRuby, because it is written in C\. MRI is the most widely used Ruby engine\.
+.IP "\(bu" 4
+Other implementations \fIhttps://www\.ruby\-lang\.org/en/about/\fR of Ruby exist\. Some of the more well\-known implementations include JRuby \fIhttps://www\.jruby\.org/\fR and TruffleRuby \fIhttps://www\.graalvm\.org/ruby/\fR\. Rubinius is an alternative implementation of Ruby written in Ruby\. JRuby is an implementation of Ruby on the JVM, short for Java Virtual Machine\. TruffleRuby is a Ruby implementation on the GraalVM, a language toolkit built on the JVM\.
+.IP "" 0
+.SS "ENGINE VERSION"
+Each application \fImay\fR specify a Ruby engine version\. If an engine version is specified, an engine \fImust\fR also be specified\. If the engine is "ruby" the engine version specified \fImust\fR match the Ruby version\.
+.IP "" 4
+.nf
+ruby "2\.6\.8", engine: "jruby", engine_version: "9\.3\.8\.0"
+.fi
+.IP "" 0
+.SS "PATCHLEVEL"
+Each application \fImay\fR specify a Ruby patchlevel\. Specifying the patchlevel has been meaningless since Ruby 2\.1\.0 was released as the patchlevel is now uniquely determined by a combination of major, minor, and teeny version numbers\.
+.P
+This option was implemented in Bundler 1\.4\.0 for Ruby 2\.0 or earlier\.
+.IP "" 4
+.nf
+ruby "3\.1\.2", patchlevel: "20"
+.fi
+.IP "" 0
+.SH "GEMS"
+Specify gem requirements using the \fBgem\fR method, with the following arguments\. All parameters are \fBOPTIONAL\fR unless otherwise specified\.
+.SS "NAME (required)"
+For each gem requirement, list a single \fIgem\fR line\.
+.IP "" 4
+.nf
+gem "nokogiri"
+.fi
+.IP "" 0
+.SS "VERSION"
+Each \fIgem\fR \fBMAY\fR have one or more version specifiers\.
+.IP "" 4
+.nf
+gem "nokogiri", ">= 1\.4\.2"
+gem "RedCloth", ">= 4\.1\.0", "< 4\.2\.0"
+.fi
+.IP "" 0
+.SS "REQUIRE AS"
+Each \fIgem\fR \fBMAY\fR specify files that should be used when autorequiring via \fBBundler\.require\fR\. You may pass an array with multiple files or \fBtrue\fR if the file you want \fBrequired\fR has the same name as \fIgem\fR or \fBfalse\fR to prevent any file from being autorequired\.
+.IP "" 4
+.nf
+gem "redis", require: ["redis/connection/hiredis", "redis"]
+gem "webmock", require: false
+gem "byebug", require: true
+.fi
+.IP "" 0
+.P
+The argument defaults to the name of the gem\. For example, these are identical:
+.IP "" 4
+.nf
+gem "nokogiri"
+gem "nokogiri", require: "nokogiri"
+gem "nokogiri", require: true
+.fi
+.IP "" 0
+.SS "GROUPS"
+Each \fIgem\fR \fBMAY\fR specify membership in one or more groups\. Any \fIgem\fR that does not specify membership in any group is placed in the \fBdefault\fR group\.
+.IP "" 4
+.nf
+gem "rspec", group: :test
+gem "wirble", groups: [:development, :test]
+.fi
+.IP "" 0
+.P
+The Bundler runtime allows its two main methods, \fBBundler\.setup\fR and \fBBundler\.require\fR, to limit their impact to particular groups\.
+.IP "" 4
+.nf
+# setup adds gems to Ruby's load path
+Bundler\.setup                    # defaults to all groups
+require "bundler/setup"          # same as Bundler\.setup
+Bundler\.setup(:default)          # only set up the _default_ group
+Bundler\.setup(:test)             # only set up the _test_ group (but `not` _default_)
+Bundler\.setup(:default, :test)   # set up the _default_ and _test_ groups, but no others
+
+# require requires all of the gems in the specified groups
+Bundler\.require                  # defaults to the _default_ group
+Bundler\.require(:default)        # identical
+Bundler\.require(:default, :test) # requires the _default_ and _test_ groups
+Bundler\.require(:test)           # requires the _test_ group
+.fi
+.IP "" 0
+.P
+The Bundler CLI allows you to specify a list of groups whose gems \fBbundle install\fR should not install with the \fBwithout\fR configuration\.
+.P
+To specify multiple groups to ignore, specify a list of groups separated by spaces\.
+.IP "" 4
+.nf
+bundle config set \-\-local without test
+bundle config set \-\-local without development test
+.fi
+.IP "" 0
+.P
+Also, calling \fBBundler\.setup\fR with no parameters, or calling \fBrequire "bundler/setup"\fR will setup all groups except for the ones you excluded via \fB\-\-without\fR (since they are not available)\.
+.P
+Note that on \fBbundle install\fR, bundler downloads and evaluates all gems, in order to create a single canonical list of all of the required gems and their dependencies\. This means that you cannot list different versions of the same gems in different groups\. For more details, see Understanding Bundler \fIhttps://bundler\.io/rationale\.html\fR\.
+.SS "PLATFORMS"
+If a gem should only be used in a particular platform or set of platforms, you can specify them\. Platforms are essentially identical to groups, except that you do not need to use the \fB\-\-without\fR install\-time flag to exclude groups of gems for other platforms\.
+.P
+There are a number of \fBGemfile\fR platforms:
+.TP
+\fBruby\fR
+C Ruby (MRI), Rubinius, or TruffleRuby, but not Windows
+.TP
+\fBmri\fR
+C Ruby (MRI) only, but not Windows
+.TP
+\fBwindows\fR
+Windows C Ruby (MRI), including RubyInstaller 32\-bit and 64\-bit versions
+.TP
+\fBmswin\fR
+Windows C Ruby (MRI), including RubyInstaller 32\-bit versions
+.TP
+\fBmswin64\fR
+Windows C Ruby (MRI), including RubyInstaller 64\-bit versions
+.TP
+\fBrbx\fR
+Rubinius
+.TP
+\fBjruby\fR
+JRuby
+.TP
+\fBtruffleruby\fR
+TruffleRuby
+.P
+On platforms \fBruby\fR, \fBmri\fR, \fBmswin\fR, \fBmswin64\fR, and \fBwindows\fR, you may additionally specify a version by appending the major and minor version numbers without a delimiter\. For example, to specify that a gem should only be used on platform \fBruby\fR version 3\.1, use:
+.IP "" 4
+.nf
+ruby_31
+.fi
+.IP "" 0
+.P
+As with groups (above), you may specify one or more platforms:
+.IP "" 4
+.nf
+gem "weakling",   platforms: :jruby
+gem "ruby\-debug", platforms: :mri_31
+gem "nokogiri",   platforms: [:windows_31, :jruby]
+.fi
+.IP "" 0
+.P
+All operations involving groups (\fBbundle install\fR \fIbundle\-install\.1\.html\fR, \fBBundler\.setup\fR, \fBBundler\.require\fR) behave exactly the same as if any groups not matching the current platform were explicitly excluded\.
+.P
+The following platform values are deprecated and should be replaced with \fBwindows\fR:
+.IP "\(bu" 4
+\fBmswin\fR, \fBmswin64\fR, \fBmingw32\fR, \fBx64_mingw\fR
+.IP "" 0
+.P
+Note that, while unfortunately using the same terminology, the values of this option are different from the values that \fBbundle lock \-\-add\-platform\fR can take\. The values of this option are more closer to "Ruby Implementation" while the values that \fBbundle lock \-\-add\-platform\fR understands are more related to OS and architecture of the different systems where your lockfile will be used\.
+.SS "FORCE_RUBY_PLATFORM"
+If you always want the pure ruby variant of a gem to be chosen over platform specific variants, you can use the \fBforce_ruby_platform\fR option:
+.IP "" 4
+.nf
+gem "ffi", force_ruby_platform: true
+.fi
+.IP "" 0
+.P
+This can be handy (assuming the pure ruby variant works fine) when:
+.IP "\(bu" 4
+You're having issues with the platform specific variant\.
+.IP "\(bu" 4
+The platform specific variant does not yet support a newer ruby (and thus has a \fBrequired_ruby_version\fR upper bound), but you still want your Gemfile{\.lock} files to resolve under that ruby\.
+.IP "" 0
+.SS "SOURCE"
+You can select an alternate RubyGems repository for a gem using the ':source' option\.
+.IP "" 4
+.nf
+gem "some_internal_gem", source: "https://gems\.example\.com"
+.fi
+.IP "" 0
+.P
+This forces the gem to be loaded from this source and ignores the global source declared at the top level of the file\. If the gem does not exist in this source, it will not be installed\.
+.P
+Bundler will search for child dependencies of this gem by first looking in the source selected for the parent, but if they are not found there, it will fall back on the global source\.
+.P
+\fBNote about a behavior of the feature deprecated in Bundler 1\.13\fR: Selecting a specific source repository this way also suppresses the ambiguous gem warning described above in \fIGLOBAL SOURCE\fR\.
+.P
+Using the \fB:source\fR option for an individual gem will also make that source available as a possible global source for any other gems which do not specify explicit sources\. Thus, when adding gems with explicit sources, it is recommended that you also ensure all other gems in the Gemfile are using explicit sources\.
+.SS "GIT"
+If necessary, you can specify that a gem is located at a particular git repository using the \fB:git\fR parameter\. The repository can be accessed via several protocols:
+.TP
+\fBHTTP(S)\fR
+gem "rails", git: "https://github\.com/rails/rails\.git"
+.TP
+\fBSSH\fR
+gem "rails", git: "git@github\.com:rails/rails\.git"
+.TP
+\fBgit\fR
+gem "rails", git: "git://github\.com/rails/rails\.git"
+.P
+If using SSH, the user that you use to run \fBbundle install\fR \fBMUST\fR have the appropriate keys available in their \fB$HOME/\.ssh\fR\.
+.P
+\fBNOTE\fR: \fBhttp://\fR and \fBgit://\fR URLs should be avoided if at all possible\. These protocols are unauthenticated, so a man\-in\-the\-middle attacker can deliver malicious code and compromise your system\. HTTPS and SSH are strongly preferred\.
+.P
+The \fBgroup\fR, \fBplatforms\fR, and \fBrequire\fR options are available and behave exactly the same as they would for a normal gem\.
+.P
+A git repository \fBSHOULD\fR have at least one file, at the root of the directory containing the gem, with the extension \fB\.gemspec\fR\. This file \fBMUST\fR contain a valid gem specification, as expected by the \fBgem build\fR command\.
+.P
+If a git repository does not have a \fB\.gemspec\fR, bundler will attempt to create one, but it will not contain any dependencies, executables, or C extension compilation instructions\. As a result, it may fail to properly integrate into your application\.
+.P
+If a git repository does have a \fB\.gemspec\fR for the gem you attached it to, a version specifier, if provided, means that the git repository is only valid if the \fB\.gemspec\fR specifies a version matching the version specifier\. If not, bundler will print a warning\.
+.IP "" 4
+.nf
+gem "rails", "2\.3\.8", git: "https://github\.com/rails/rails\.git"
+# bundle install will fail, because the \.gemspec in the rails
+# repository's master branch specifies version 3\.0\.0
+.fi
+.IP "" 0
+.P
+If a git repository does \fBnot\fR have a \fB\.gemspec\fR for the gem you attached it to, a version specifier \fBMUST\fR be provided\. Bundler will use this version in the simple \fB\.gemspec\fR it creates\.
+.P
+Git repositories support a number of additional options\.
+.TP
+\fBbranch\fR, \fBtag\fR, and \fBref\fR
+You \fBMUST\fR only specify at most one of these options\. The default is \fBbranch: "master"\fR\. For example:
+.IP
+gem "rails", git: "https://github\.com/rails/rails\.git", branch: "5\-0\-stable"
+.IP
+gem "rails", git: "https://github\.com/rails/rails\.git", tag: "v5\.0\.0"
+.IP
+gem "rails", git: "https://github\.com/rails/rails\.git", ref: "4aded"
+.TP
+\fBsubmodules\fR
+For reference, a git submodule \fIhttps://git\-scm\.com/book/en/v2/Git\-Tools\-Submodules\fR lets you have another git repository within a subfolder of your repository\. Specify \fBsubmodules: true\fR to cause bundler to expand any submodules included in the git repository
+.P
+If a git repository contains multiple \fB\.gemspecs\fR, each \fB\.gemspec\fR represents a gem located at the same place in the file system as the \fB\.gemspec\fR\.
+.IP "" 4
+.nf
+|~rails                   [git root]
+| |\-rails\.gemspec         [rails gem located here]
+|~actionpack
+| |\-actionpack\.gemspec    [actionpack gem located here]
+|~activesupport
+| |\-activesupport\.gemspec [activesupport gem located here]
+|\|\.\|\.\|\.
+.fi
+.IP "" 0
+.P
+To install a gem located in a git repository, bundler changes to the directory containing the gemspec, runs \fBgem build name\.gemspec\fR and then installs the resulting gem\. The \fBgem build\fR command, which comes standard with Rubygems, evaluates the \fB\.gemspec\fR in the context of the directory in which it is located\.
+.SS "GIT SOURCE"
+A custom git source can be defined via the \fBgit_source\fR method\. Provide the source's name as an argument, and a block which receives a single argument and interpolates it into a string to return the full repo address:
+.IP "" 4
+.nf
+git_source(:stash){ |repo_name| "https://stash\.corp\.acme\.pl/#{repo_name}\.git" }
+gem 'rails', stash: 'forks/rails'
+.fi
+.IP "" 0
+.P
+In addition, if you wish to choose a specific branch:
+.IP "" 4
+.nf
+gem "rails", stash: "forks/rails", branch: "branch_name"
+.fi
+.IP "" 0
+.SS "GITHUB"
+\fBNOTE\fR: This shorthand should be avoided until Bundler 2\.0, since it currently expands to an insecure \fBgit://\fR URL\. This allows a man\-in\-the\-middle attacker to compromise your system\.
+.P
+If the git repository you want to use is hosted on GitHub and is public, you can use the :github shorthand to specify the github username and repository name (without the trailing "\.git"), separated by a slash\. If both the username and repository name are the same, you can omit one\.
+.IP "" 4
+.nf
+gem "rails", github: "rails/rails"
+gem "rails", github: "rails"
+.fi
+.IP "" 0
+.P
+Are both equivalent to
+.IP "" 4
+.nf
+gem "rails", git: "https://github\.com/rails/rails\.git"
+.fi
+.IP "" 0
+.P
+Since the \fBgithub\fR method is a specialization of \fBgit_source\fR, it accepts a \fB:branch\fR named argument\.
+.P
+You can also directly pass a pull request URL:
+.IP "" 4
+.nf
+gem "rails", github: "https://github\.com/rails/rails/pull/43753"
+.fi
+.IP "" 0
+.P
+Which is equivalent to:
+.IP "" 4
+.nf
+gem "rails", github: "rails/rails", branch: "refs/pull/43753/head"
+.fi
+.IP "" 0
+.SS "GIST"
+If the git repository you want to use is hosted as a GitHub Gist and is public, you can use the :gist shorthand to specify the gist identifier (without the trailing "\.git")\.
+.IP "" 4
+.nf
+gem "the_hatch", gist: "4815162342"
+.fi
+.IP "" 0
+.P
+Is equivalent to:
+.IP "" 4
+.nf
+gem "the_hatch", git: "https://gist\.github\.com/4815162342\.git"
+.fi
+.IP "" 0
+.P
+Since the \fBgist\fR method is a specialization of \fBgit_source\fR, it accepts a \fB:branch\fR named argument\.
+.SS "BITBUCKET"
+If the git repository you want to use is hosted on Bitbucket and is public, you can use the :bitbucket shorthand to specify the bitbucket username and repository name (without the trailing "\.git"), separated by a slash\. If both the username and repository name are the same, you can omit one\.
+.IP "" 4
+.nf
+gem "rails", bitbucket: "rails/rails"
+gem "rails", bitbucket: "rails"
+.fi
+.IP "" 0
+.P
+Are both equivalent to
+.IP "" 4
+.nf
+gem "rails", git: "https://rails@bitbucket\.org/rails/rails\.git"
+.fi
+.IP "" 0
+.P
+Since the \fBbitbucket\fR method is a specialization of \fBgit_source\fR, it accepts a \fB:branch\fR named argument\.
+.SS "PATH"
+You can specify that a gem is located in a particular location on the file system\. Relative paths are resolved relative to the directory containing the \fBGemfile\fR\.
+.P
+Similar to the semantics of the \fB:git\fR option, the \fB:path\fR option requires that the directory in question either contains a \fB\.gemspec\fR for the gem, or that you specify an explicit version that bundler should use\.
+.P
+Unlike \fB:git\fR, bundler does not compile C extensions for gems specified as paths\.
+.IP "" 4
+.nf
+gem "rails", path: "vendor/rails"
+.fi
+.IP "" 0
+.P
+If you would like to use multiple local gems directly from the filesystem, you can set a global \fBpath\fR option to the path containing the gem's files\. This will automatically load gemspec files from subdirectories\.
+.IP "" 4
+.nf
+path 'components' do
+  gem 'admin_ui'
+  gem 'public_ui'
+end
+.fi
+.IP "" 0
+.SH "BLOCK FORM OF SOURCE, GIT, PATH, GROUP and PLATFORMS"
+The \fB:source\fR, \fB:git\fR, \fB:path\fR, \fB:group\fR, and \fB:platforms\fR options may be applied to a group of gems by using block form\.
+.IP "" 4
+.nf
+source "https://gems\.example\.com" do
+  gem "some_internal_gem"
+  gem "another_internal_gem"
+end
+
+git "https://github\.com/rails/rails\.git" do
+  gem "activesupport"
+  gem "actionpack"
+end
+
+platforms :ruby do
+  gem "ruby\-debug"
+  gem "sqlite3"
+end
+
+group :development, optional: true do
+  gem "wirble"
+  gem "faker"
+end
+.fi
+.IP "" 0
+.P
+In the case of the group block form the :optional option can be given to prevent a group from being installed unless listed in the \fB\-\-with\fR option given to the \fBbundle install\fR command\.
+.P
+In the case of the \fBgit\fR block form, the \fB:ref\fR, \fB:branch\fR, \fB:tag\fR, and \fB:submodules\fR options may be passed to the \fBgit\fR method, and all gems in the block will inherit those options\.
+.P
+The presence of a \fBsource\fR block in a Gemfile also makes that source available as a possible global source for any other gems which do not specify explicit sources\. Thus, when defining source blocks, it is recommended that you also ensure all other gems in the Gemfile are using explicit sources, either via source blocks or \fB:source\fR directives on individual gems\.
+.SH "INSTALL_IF"
+The \fBinstall_if\fR method allows gems to be installed based on a proc or lambda\. This is especially useful for optional gems that can only be used if certain software is installed or some other conditions are met\.
+.IP "" 4
+.nf
+install_if \-> { RUBY_PLATFORM =~ /darwin/ } do
+  gem "pasteboard"
+end
+.fi
+.IP "" 0
+.SH "GEMSPEC"
+The \fB\.gemspec\fR \fIhttps://guides\.rubygems\.org/specification\-reference/\fR file is where you provide metadata about your gem to Rubygems\. Some required Gemspec attributes include the name, description, and homepage of your gem\. This is also where you specify the dependencies your gem needs to run\.
+.P
+If you wish to use Bundler to help install dependencies for a gem while it is being developed, use the \fBgemspec\fR method to pull in the dependencies listed in the \fB\.gemspec\fR file\.
+.P
+The \fBgemspec\fR method adds any runtime dependencies as gem requirements in the default group\. It also adds development dependencies as gem requirements in the \fBdevelopment\fR group\. Finally, it adds a gem requirement on your project (\fBpath: '\.'\fR)\. In conjunction with \fBBundler\.setup\fR, this allows you to require project files in your test code as you would if the project were installed as a gem; you need not manipulate the load path manually or require project files via relative paths\.
+.P
+The \fBgemspec\fR method supports optional \fB:path\fR, \fB:glob\fR, \fB:name\fR, and \fB:development_group\fR options, which control where bundler looks for the \fB\.gemspec\fR, the glob it uses to look for the gemspec (defaults to: \fB{,*,*/*}\.gemspec\fR), what named \fB\.gemspec\fR it uses (if more than one is present), and which group development dependencies are included in\.
+.P
+When a \fBgemspec\fR dependency encounters version conflicts during resolution, the local version under development will always be selected \-\- even if there are remote versions that better match other requirements for the \fBgemspec\fR gem\.
+.SH "OVERRIDE"
+The \fBoverride\fR directive rewrites a constraint on another gem before resolution runs\. It targets the common case where an upstream gem's published metadata is too narrow on the current project's machine \-\- a stale upper bound, an unwanted floor, or a transitive pin that has to be lifted\.
+.IP "" 4
+.nf
+override <target>, <field>: <operation>
+.fi
+.IP "" 0
+.P
+\fB<target>\fR is a gem name string or \fB:all\fR\. \fB<field>\fR is one of \fBversion:\fR, \fBrequired_ruby_version:\fR, or \fBrequired_rubygems_version:\fR\. \fB<operation>\fR is one of:
+.IP "\(bu" 4
+a version requirement string (e\.g\. \fB">= 8\.0"\fR), which \fBreplaces\fR the target's requirement absolutely\. The original requirement, both direct and transitive, is discarded in favour of the override\.
+.IP "\(bu" 4
+\fB:ignore_upper\fR, which removes upper\-bound operators (\fB<\fR and \fB<=\fR) from the existing requirement and folds \fB~>\fR into its lower bound (\fB~> 1\.5\fR becomes \fB>= 1\.5\fR)\. Other operators, including \fB!=\fR, are preserved\.
+.IP "\(bu" 4
+\fBnil\fR, which collapses the requirement to \fB>= 0\fR (no constraint at all)\.
+.IP "" 0
+.P
+\fB:all\fR only applies to \fBrequired_ruby_version:\fR and \fBrequired_rubygems_version:\fR\. A per\-gem override on the same field takes precedence over an \fB:all\fR override\. \fB:all + version:\fR is rejected: version requirements only make sense per gem\.
+.P
+Multiple \fBoverride\fR calls for distinct targets are allowed; declaring the same \fBtarget\fR and \fBfield\fR twice is an error\.
+.IP "" 4
+.nf
+source "https://rubygems\.org"
+
+# Force every reference to "rails" \-\- direct or transitive \-\- to >= 8\.0\.
+override "rails", version: ">= 8\.0"
+
+# Strip the upper bound on nokogiri\.
+override "nokogiri", version: :ignore_upper
+
+# Drop the version pin on legacy entirely\.
+override "legacy", version: nil
+
+# Loosen every gem's required_ruby_version upper bound\.
+override :all, required_ruby_version: :ignore_upper
+
+# Override one specific gem's required_rubygems_version\.
+override "tricky", required_rubygems_version: nil
+
+gem "rails", "~> 7\.0"
+.fi
+.IP "" 0
+.P
+The override only affects resolution and the install\-time Ruby/RubyGems compatibility checks; \fBGemfile\.lock\fR continues to reflect the resolved versions, not the rewritten requirements\. When resolution still fails, Bundler appends the active overrides (with their Gemfile location) to the error message so it is clear which override shaped the constraint set\.
+.SH "SOURCE PRIORITY"
+When attempting to locate a gem to satisfy a gem requirement, bundler uses the following priority order:
+.IP "1." 4
+The source explicitly attached to the gem (using \fB:source\fR, \fB:path\fR, or \fB:git\fR)
+.IP "2." 4
+For implicit gems (dependencies of explicit gems), any source, git, or path repository declared on the parent\. This results in bundler prioritizing the ActiveSupport gem from the Rails git repository over ones from \fBrubygems\.org\fR
+.IP "3." 4
+If neither of the above conditions are met, the global source will be used\. If multiple global sources are specified, they will be prioritized from last to first, but this is deprecated since Bundler 1\.13, so Bundler prints a warning and will abort with an error in the future\.
+.IP "" 0
+.SH "LOCKFILE"
+By default, Bundler will create a lockfile by adding \fB\.lock\fR to the end of the Gemfile name\. To change this, use the \fBlockfile\fR method:
+.IP "" 4
+.nf
+lockfile "/path/to/lockfile\.lock"
+.fi
+.IP "" 0
+.P
+This is useful when you want to use different lockfiles per ruby version or platform\.
+.P
+To avoid writing a lock file, use \fBfalse\fR as the argument:
+.IP "" 4
+.nf
+lockfile false
+.fi
+.IP "" 0
+.P
+This is useful for library development and other situations where the code is expected to work with a range of dependency versions\.
+.SS "LOCKFILE PRECEDENCE"
+When determining path to the lockfile or whether to create a lockfile, the following precedence is used:
+.IP "1." 4
+The \fBbundle install\fR \fB\-\-no\-lock\fR option (which disables lockfile creation)\.
+.IP "2." 4
+The \fBbundle install\fR \fB\-\-lockfile\fR option\.
+.IP "3." 4
+The \fBBUNDLE_LOCKFILE\fR environment variable\.
+.IP "4." 4
+The \fBlockfile\fR method in the Gemfile\.
+.IP "5." 4
+The default behavior of adding \fB\.lock\fR to the end of the Gemfile name\.
+.IP "" 0
+
diff --git a/lib/bundler/man/gemfile.5.ronn b/lib/bundler/man/gemfile.5.ronn
new file mode 100644
index 0000000000..69fef90654
--- /dev/null
+++ b/lib/bundler/man/gemfile.5.ronn
@@ -0,0 +1,639 @@
+Gemfile(5) -- A format for describing gem dependencies for Ruby programs
+========================================================================
+
+## SYNOPSIS
+
+A `Gemfile` describes the gem dependencies required to execute associated
+Ruby code.
+
+Place the `Gemfile` in the root of the directory containing the associated
+code. For instance, in a Rails application, place the `Gemfile` in the same
+directory as the `Rakefile`.
+
+## SYNTAX
+
+A `Gemfile` is evaluated as Ruby code, in a context which makes available
+a number of methods used to describe the gem requirements.
+
+## GLOBAL SOURCE
+
+At the top of the `Gemfile`, add a single line for the `RubyGems` source that
+contains the gems listed in the `Gemfile`.
+
+    source "https://rubygems.org"
+
+You can add only one global source. In Bundler 1.13, adding multiple global
+sources was deprecated. The `source` `MUST` be a valid RubyGems repository.
+
+To use more than one source of RubyGems, you should use [`source` block
+](#BLOCK-FORM-OF-SOURCE-GIT-PATH-GROUP-and-PLATFORMS).
+
+A source is checked for gems following the heuristics described in
+[SOURCE PRIORITY][].
+
+**Note about a behavior of the feature deprecated in Bundler 1.13**:
+If a gem is found in more than one global source, Bundler
+will print a warning after installing the gem indicating which source was used,
+and listing the other sources where the gem is available. A specific source can
+be selected for gems that need to use a non-standard repository, suppressing
+this warning, by using the [`:source` option](#SOURCE) or `source` block.
+
+### CREDENTIALS
+
+Some gem sources require a username and password. Use [bundle config(1)](bundle-config.1.html) to set
+the username and password for any of the sources that need it. The command must
+be run once on each computer that will install the Gemfile, but this keeps the
+credentials from being stored in plain text in version control.
+
+    bundle config gems.example.com user:password
+
+For some sources, like a company Gemfury account, it may be easier to
+include the credentials in the Gemfile as part of the source URL.
+
+    source "https://user:password@gems.example.com"
+
+Credentials in the source URL will take precedence over credentials set using
+`config`.
+
+## RUBY
+
+If your application requires a specific Ruby version or engine, specify your
+requirements using the `ruby` method, with the following arguments.
+All parameters are `OPTIONAL` unless otherwise specified.
+
+### VERSION (required)
+
+The version of Ruby that your application requires. If your application
+requires an alternate Ruby engine, such as JRuby, TruffleRuby, etc., this
+should be the Ruby version that the engine is compatible with.
+
+    ruby "3.1.2"
+
+If you wish to derive your Ruby version from a version file (ie .ruby-version),
+you can use the `file` option instead.
+
+    ruby file: ".ruby-version"
+
+The version file should conform to any of the following formats:
+
+  - `3.1.2` (.ruby-version)
+  - `ruby 3.1.2` (.tool-versions, read: https://asdf-vm.com/manage/configuration.html#tool-versions)
+
+### ENGINE
+
+Each application _may_ specify a Ruby engine. If an engine is specified, an
+engine version _must_ also be specified.
+
+What exactly is an Engine?
+  - A Ruby engine is an implementation of the Ruby language.
+
+  - For background: the reference or original implementation of the Ruby
+    programming language is called
+    [Matz's Ruby Interpreter](https://en.wikipedia.org/wiki/Ruby_MRI), or  MRI
+    for short. This is named after Ruby creator Yukihiro Matsumoto,
+    also known as Matz. MRI is also known as CRuby, because it is written in C.
+    MRI is the most widely used Ruby engine.
+
+  - [Other implementations](https://www.ruby-lang.org/en/about/) of Ruby exist.
+    Some of the more well-known implementations include
+    [JRuby](https://www.jruby.org/) and [TruffleRuby](https://www.graalvm.org/ruby/).
+    Rubinius is an alternative implementation of Ruby written in Ruby.
+    JRuby is an implementation of Ruby on the JVM, short for Java Virtual Machine.
+    TruffleRuby is a Ruby implementation on the GraalVM, a language toolkit built on the JVM.
+
+### ENGINE VERSION
+
+Each application _may_ specify a Ruby engine version. If an engine version is
+specified, an engine _must_ also be specified. If the engine is "ruby" the
+engine version specified _must_ match the Ruby version.
+
+    ruby "2.6.8", engine: "jruby", engine_version: "9.3.8.0"
+
+### PATCHLEVEL
+
+Each application _may_ specify a Ruby patchlevel. Specifying the patchlevel has
+been meaningless since Ruby 2.1.0 was released as the patchlevel is now
+uniquely determined by a combination of major, minor, and teeny version numbers.
+
+This option was implemented in Bundler 1.4.0 for Ruby 2.0 or earlier.
+
+    ruby "3.1.2", patchlevel: "20"
+
+## GEMS
+
+Specify gem requirements using the `gem` method, with the following arguments.
+All parameters are `OPTIONAL` unless otherwise specified.
+
+### NAME (required)
+
+For each gem requirement, list a single _gem_ line.
+
+    gem "nokogiri"
+
+### VERSION
+
+Each _gem_ `MAY` have one or more version specifiers.
+
+    gem "nokogiri", ">= 1.4.2"
+    gem "RedCloth", ">= 4.1.0", "< 4.2.0"
+
+### REQUIRE AS
+
+Each _gem_ `MAY` specify files that should be used when autorequiring via
+`Bundler.require`. You may pass an array with multiple files or `true` if the file
+you want `required` has the same name as _gem_ or `false` to
+prevent any file from being autorequired.
+
+    gem "redis", require: ["redis/connection/hiredis", "redis"]
+    gem "webmock", require: false
+    gem "byebug", require: true
+
+The argument defaults to the name of the gem. For example, these are identical:
+
+    gem "nokogiri"
+    gem "nokogiri", require: "nokogiri"
+    gem "nokogiri", require: true
+
+### GROUPS
+
+Each _gem_ `MAY` specify membership in one or more groups. Any _gem_ that does
+not specify membership in any group is placed in the `default` group.
+
+    gem "rspec", group: :test
+    gem "wirble", groups: [:development, :test]
+
+The Bundler runtime allows its two main methods, `Bundler.setup` and
+`Bundler.require`, to limit their impact to particular groups.
+
+    # setup adds gems to Ruby's load path
+    Bundler.setup                    # defaults to all groups
+    require "bundler/setup"          # same as Bundler.setup
+    Bundler.setup(:default)          # only set up the _default_ group
+    Bundler.setup(:test)             # only set up the _test_ group (but `not` _default_)
+    Bundler.setup(:default, :test)   # set up the _default_ and _test_ groups, but no others
+
+    # require requires all of the gems in the specified groups
+    Bundler.require                  # defaults to the _default_ group
+    Bundler.require(:default)        # identical
+    Bundler.require(:default, :test) # requires the _default_ and _test_ groups
+    Bundler.require(:test)           # requires the _test_ group
+
+The Bundler CLI allows you to specify a list of groups whose gems `bundle install` should
+not install with the `without` configuration.
+
+To specify multiple groups to ignore, specify a list of groups separated by spaces.
+
+    bundle config set --local without test
+    bundle config set --local without development test
+
+Also, calling `Bundler.setup` with no parameters, or calling `require "bundler/setup"`
+will setup all groups except for the ones you excluded via `--without` (since they
+are not available).
+
+Note that on `bundle install`, bundler downloads and evaluates all gems, in order to
+create a single canonical list of all of the required gems and their dependencies.
+This means that you cannot list different versions of the same gems in different
+groups. For more details, see [Understanding Bundler](https://bundler.io/rationale.html).
+
+### PLATFORMS
+
+If a gem should only be used in a particular platform or set of platforms, you can
+specify them. Platforms are essentially identical to groups, except that you do not
+need to use the `--without` install-time flag to exclude groups of gems for other
+platforms.
+
+There are a number of `Gemfile` platforms:
+
+  * `ruby`:
+    C Ruby (MRI), Rubinius, or TruffleRuby, but not Windows
+  * `mri`:
+    C Ruby (MRI) only, but not Windows
+  * `windows`:
+    Windows C Ruby (MRI), including RubyInstaller 32-bit and 64-bit versions
+  * `mswin`:
+    Windows C Ruby (MRI), including RubyInstaller 32-bit versions
+  * `mswin64`:
+    Windows C Ruby (MRI), including RubyInstaller 64-bit versions
+  * `rbx`:
+    Rubinius
+  * `jruby`:
+    JRuby
+  * `truffleruby`:
+    TruffleRuby
+
+On platforms `ruby`, `mri`, `mswin`, `mswin64`, and `windows`, you may
+additionally specify a version by appending the major and minor version numbers
+without a delimiter. For example, to specify that a gem should only be used on
+platform `ruby` version 3.1, use:
+
+    ruby_31
+
+As with groups (above), you may specify one or more platforms:
+
+    gem "weakling",   platforms: :jruby
+    gem "ruby-debug", platforms: :mri_31
+    gem "nokogiri",   platforms: [:windows_31, :jruby]
+
+All operations involving groups ([`bundle install`](bundle-install.1.html), `Bundler.setup`,
+`Bundler.require`) behave exactly the same as if any groups not
+matching the current platform were explicitly excluded.
+
+The following platform values are deprecated and should be replaced with `windows`:
+
+  * `mswin`, `mswin64`, `mingw32`, `x64_mingw`
+
+Note that, while unfortunately using the same terminology, the values of this
+option are different from the values that `bundle lock --add-platform` can take.
+The values of this option are more closer to "Ruby Implementation" while the
+values that `bundle lock --add-platform` understands are more related to OS and
+architecture of the different systems where your lockfile will be used.
+
+### FORCE_RUBY_PLATFORM
+
+If you always want the pure ruby variant of a gem to be chosen over platform
+specific variants, you can use the `force_ruby_platform` option:
+
+    gem "ffi", force_ruby_platform: true
+
+This can be handy (assuming the pure ruby variant works fine) when:
+
+* You're having issues with the platform specific variant.
+* The platform specific variant does not yet support a newer ruby (and thus has
+  a `required_ruby_version` upper bound), but you still want your Gemfile{.lock}
+  files to resolve under that ruby.
+
+### SOURCE
+
+You can select an alternate RubyGems repository for a gem using the ':source'
+option.
+
+    gem "some_internal_gem", source: "https://gems.example.com"
+
+This forces the gem to be loaded from this source and ignores the global source
+declared at the top level of the file. If the gem does not exist in this source,
+it will not be installed.
+
+Bundler will search for child dependencies of this gem by first looking in the
+source selected for the parent, but if they are not found there, it will fall
+back on the global source.
+
+**Note about a behavior of the feature deprecated in Bundler 1.13**:
+Selecting a specific source repository this way also suppresses the ambiguous
+gem warning described above in [GLOBAL SOURCE](#GLOBAL-SOURCE).
+
+Using the `:source` option for an individual gem will also make that source
+available as a possible global source for any other gems which do not specify
+explicit sources. Thus, when adding gems with explicit sources, it is
+recommended that you also ensure all other gems in the Gemfile are using
+explicit sources.
+
+### GIT
+
+If necessary, you can specify that a gem is located at a particular
+git repository using the `:git` parameter. The repository can be accessed via
+several protocols:
+
+  * `HTTP(S)`:
+    gem "rails", git: "https://github.com/rails/rails.git"
+  * `SSH`:
+    gem "rails", git: "git@github.com:rails/rails.git"
+  * `git`:
+    gem "rails", git: "git://github.com/rails/rails.git"
+
+If using SSH, the user that you use to run `bundle install` `MUST` have the
+appropriate keys available in their `$HOME/.ssh`.
+
+`NOTE`: `http://` and `git://` URLs should be avoided if at all possible. These
+protocols are unauthenticated, so a man-in-the-middle attacker can deliver
+malicious code and compromise your system. HTTPS and SSH are strongly
+preferred.
+
+The `group`, `platforms`, and `require` options are available and behave
+exactly the same as they would for a normal gem.
+
+A git repository `SHOULD` have at least one file, at the root of the
+directory containing the gem, with the extension `.gemspec`. This file
+`MUST` contain a valid gem specification, as expected by the `gem build`
+command.
+
+If a git repository does not have a `.gemspec`, bundler will attempt to
+create one, but it will not contain any dependencies, executables, or
+C extension compilation instructions. As a result, it may fail to properly
+integrate into your application.
+
+If a git repository does have a `.gemspec` for the gem you attached it
+to, a version specifier, if provided, means that the git repository is
+only valid if the `.gemspec` specifies a version matching the version
+specifier. If not, bundler will print a warning.
+
+    gem "rails", "2.3.8", git: "https://github.com/rails/rails.git"
+    # bundle install will fail, because the .gemspec in the rails
+    # repository's master branch specifies version 3.0.0
+
+If a git repository does `not` have a `.gemspec` for the gem you attached
+it to, a version specifier `MUST` be provided. Bundler will use this
+version in the simple `.gemspec` it creates.
+
+Git repositories support a number of additional options.
+
+  * `branch`, `tag`, and `ref`:
+    You `MUST` only specify at most one of these options. The default
+    is `branch: "master"`.  For example:
+
+      gem "rails", git: "https://github.com/rails/rails.git", branch: "5-0-stable"
+
+      gem "rails", git: "https://github.com/rails/rails.git", tag: "v5.0.0"
+
+      gem "rails", git: "https://github.com/rails/rails.git", ref: "4aded"
+
+  * `submodules`:
+    For reference, a [git submodule](https://git-scm.com/book/en/v2/Git-Tools-Submodules)
+    lets you have another git repository within a subfolder of your repository.
+    Specify `submodules: true` to cause bundler to expand any
+    submodules included in the git repository
+
+If a git repository contains multiple `.gemspecs`, each `.gemspec`
+represents a gem located at the same place in the file system as
+the `.gemspec`.
+
+    |~rails                   [git root]
+    | |-rails.gemspec         [rails gem located here]
+    |~actionpack
+    | |-actionpack.gemspec    [actionpack gem located here]
+    |~activesupport
+    | |-activesupport.gemspec [activesupport gem located here]
+    |...
+
+To install a gem located in a git repository, bundler changes to
+the directory containing the gemspec, runs `gem build name.gemspec`
+and then installs the resulting gem. The `gem build` command,
+which comes standard with Rubygems, evaluates the `.gemspec` in
+the context of the directory in which it is located.
+
+### GIT SOURCE
+
+A custom git source can be defined via the `git_source` method. Provide the source's name
+as an argument, and a block which receives a single argument and interpolates it into a
+string to return the full repo address:
+
+    git_source(:stash){ |repo_name| "https://stash.corp.acme.pl/#{repo_name}.git" }
+    gem 'rails', stash: 'forks/rails'
+
+In addition, if you wish to choose a specific branch:
+
+    gem "rails", stash: "forks/rails", branch: "branch_name"
+
+### GITHUB
+
+`NOTE`: This shorthand should be avoided until Bundler 2.0, since it
+currently expands to an insecure `git://` URL. This allows a
+man-in-the-middle attacker to compromise your system.
+
+If the git repository you want to use is hosted on GitHub and is public, you can use the
+:github shorthand to specify the github username and repository name (without the
+trailing ".git"), separated by a slash. If both the username and repository name are the
+same, you can omit one.
+
+    gem "rails", github: "rails/rails"
+    gem "rails", github: "rails"
+
+Are both equivalent to
+
+    gem "rails", git: "https://github.com/rails/rails.git"
+
+Since the `github` method is a specialization of `git_source`, it accepts a `:branch` named argument.
+
+You can also directly pass a pull request URL:
+
+    gem "rails", github: "https://github.com/rails/rails/pull/43753"
+
+Which is equivalent to:
+
+    gem "rails", github: "rails/rails", branch: "refs/pull/43753/head"
+
+### GIST
+
+If the git repository you want to use is hosted as a GitHub Gist and is public, you can use
+the :gist shorthand to specify the gist identifier (without the trailing ".git").
+
+    gem "the_hatch", gist: "4815162342"
+
+Is equivalent to:
+
+    gem "the_hatch", git: "https://gist.github.com/4815162342.git"
+
+Since the `gist` method is a specialization of `git_source`, it accepts a `:branch` named argument.
+
+### BITBUCKET
+
+If the git repository you want to use is hosted on Bitbucket and is public, you can use the
+:bitbucket shorthand to specify the bitbucket username and repository name (without the
+trailing ".git"), separated by a slash. If both the username and repository name are the
+same, you can omit one.
+
+    gem "rails", bitbucket: "rails/rails"
+    gem "rails", bitbucket: "rails"
+
+Are both equivalent to
+
+    gem "rails", git: "https://rails@bitbucket.org/rails/rails.git"
+
+Since the `bitbucket` method is a specialization of `git_source`, it accepts a `:branch` named argument.
+
+### PATH
+
+You can specify that a gem is located in a particular location
+on the file system. Relative paths are resolved relative to the
+directory containing the `Gemfile`.
+
+Similar to the semantics of the `:git` option, the `:path`
+option requires that the directory in question either contains
+a `.gemspec` for the gem, or that you specify an explicit
+version that bundler should use.
+
+Unlike `:git`, bundler does not compile C extensions for
+gems specified as paths.
+
+    gem "rails", path: "vendor/rails"
+
+If you would like to use multiple local gems directly from the filesystem, you can set a global `path` option to the path containing the gem's files. This will automatically load gemspec files from subdirectories.
+
+    path 'components' do
+      gem 'admin_ui'
+      gem 'public_ui'
+    end
+
+## BLOCK FORM OF SOURCE, GIT, PATH, GROUP and PLATFORMS
+
+The `:source`, `:git`, `:path`, `:group`, and `:platforms` options may be
+applied to a group of gems by using block form.
+
+    source "https://gems.example.com" do
+      gem "some_internal_gem"
+      gem "another_internal_gem"
+    end
+
+    git "https://github.com/rails/rails.git" do
+      gem "activesupport"
+      gem "actionpack"
+    end
+
+    platforms :ruby do
+      gem "ruby-debug"
+      gem "sqlite3"
+    end
+
+    group :development, optional: true do
+      gem "wirble"
+      gem "faker"
+    end
+
+In the case of the group block form the :optional option can be given
+to prevent a group from being installed unless listed in the `--with`
+option given to the `bundle install` command.
+
+In the case of the `git` block form, the `:ref`, `:branch`, `:tag`,
+and `:submodules` options may be passed to the `git` method, and
+all gems in the block will inherit those options.
+
+The presence of a `source` block in a Gemfile also makes that source
+available as a possible global source for any other gems which do not specify
+explicit sources. Thus, when defining source blocks, it is
+recommended that you also ensure all other gems in the Gemfile are using
+explicit sources, either via source blocks or `:source` directives on
+individual gems.
+
+## INSTALL_IF
+
+The `install_if` method allows gems to be installed based on a proc or lambda.
+This is especially useful for optional gems that can only be used if certain
+software is installed or some other conditions are met.
+
+    install_if -> { RUBY_PLATFORM =~ /darwin/ } do
+      gem "pasteboard"
+    end
+
+## GEMSPEC
+
+The [`.gemspec`](https://guides.rubygems.org/specification-reference/) file is where
+ you provide metadata about your gem to Rubygems. Some required Gemspec
+ attributes include the name, description, and homepage of your gem. This is
+ also where you specify the dependencies your gem needs to run.
+
+If you wish to use Bundler to help install dependencies for a gem while it is
+being developed, use the `gemspec` method to pull in the dependencies listed in
+the `.gemspec` file.
+
+The `gemspec` method adds any runtime dependencies as gem requirements in the
+default group. It also adds development dependencies as gem requirements in the
+`development` group. Finally, it adds a gem requirement on your project (`path:
+'.'`). In conjunction with `Bundler.setup`, this allows you to require project
+files in your test code as you would if the project were installed as a gem; you
+need not manipulate the load path manually or require project files via relative
+paths.
+
+The `gemspec` method supports optional `:path`, `:glob`, `:name`, and `:development_group`
+options, which control where bundler looks for the `.gemspec`, the glob it uses to look
+for the gemspec (defaults to: `{,*,*/*}.gemspec`), what named `.gemspec` it uses
+(if more than one is present), and which group development dependencies are included in.
+
+When a `gemspec` dependency encounters version conflicts during resolution, the
+local version under development will always be selected -- even if there are
+remote versions that better match other requirements for the `gemspec` gem.
+
+## OVERRIDE
+
+The `override` directive rewrites a constraint on another gem before
+resolution runs. It targets the common case where an upstream gem's
+published metadata is too narrow on the current project's machine -- a stale
+upper bound, an unwanted floor, or a transitive pin that has to be lifted.
+
+    override <target>, <field>: <operation>
+
+`<target>` is a gem name string or `:all`. `<field>` is one of `version:`,
+`required_ruby_version:`, or `required_rubygems_version:`. `<operation>` is
+one of:
+
+  * a version requirement string (e.g. `">= 8.0"`), which **replaces** the
+    target's requirement absolutely. The original requirement, both direct
+    and transitive, is discarded in favour of the override.
+  * `:ignore_upper`, which removes upper-bound operators (`<` and `<=`) from
+    the existing requirement and folds `~>` into its lower bound (`~> 1.5`
+    becomes `>= 1.5`). Other operators, including `!=`, are preserved.
+  * `nil`, which collapses the requirement to `>= 0` (no constraint at all).
+
+`:all` only applies to `required_ruby_version:` and `required_rubygems_version:`.
+A per-gem override on the same field takes precedence over an `:all` override.
+`:all + version:` is rejected: version requirements only make sense per gem.
+
+Multiple `override` calls for distinct targets are allowed; declaring the
+same `target` and `field` twice is an error.
+
+    source "https://rubygems.org"
+
+    # Force every reference to "rails" -- direct or transitive -- to >= 8.0.
+    override "rails", version: ">= 8.0"
+
+    # Strip the upper bound on nokogiri.
+    override "nokogiri", version: :ignore_upper
+
+    # Drop the version pin on legacy entirely.
+    override "legacy", version: nil
+
+    # Loosen every gem's required_ruby_version upper bound.
+    override :all, required_ruby_version: :ignore_upper
+
+    # Override one specific gem's required_rubygems_version.
+    override "tricky", required_rubygems_version: nil
+
+    gem "rails", "~> 7.0"
+
+The override only affects resolution and the install-time Ruby/RubyGems
+compatibility checks; `Gemfile.lock` continues to reflect the resolved
+versions, not the rewritten requirements. When resolution still fails,
+Bundler appends the active overrides (with their Gemfile location) to the
+error message so it is clear which override shaped the constraint set.
+
+## SOURCE PRIORITY
+
+When attempting to locate a gem to satisfy a gem requirement,
+bundler uses the following priority order:
+
+  1. The source explicitly attached to the gem (using `:source`, `:path`, or
+     `:git`)
+  2. For implicit gems (dependencies of explicit gems), any source, git, or path
+     repository declared on the parent. This results in bundler prioritizing the
+     ActiveSupport gem from the Rails git repository over ones from
+     `rubygems.org`
+  3. If neither of the above conditions are met, the global source will be used.
+     If multiple global sources are specified, they will be prioritized from
+     last to first, but this is deprecated since Bundler 1.13, so Bundler prints
+     a warning and will abort with an error in the future.
+
+## LOCKFILE
+
+By default, Bundler will create a lockfile by adding `.lock` to the end of the
+Gemfile name. To change this, use the `lockfile` method:
+
+    lockfile "/path/to/lockfile.lock"
+
+This is useful when you want to use different lockfiles per ruby version or
+platform.
+
+To avoid writing a lock file, use `false` as the argument:
+
+    lockfile false
+
+This is useful for library development and other situations where the code is
+expected to work with a range of dependency versions.
+
+### LOCKFILE PRECEDENCE
+
+When determining path to the lockfile or whether to create a lockfile, the
+following precedence is used:
+
+1. The `bundle install` `--no-lock` option (which disables lockfile creation).
+1. The `bundle install` `--lockfile` option.
+1. The `BUNDLE_LOCKFILE` environment variable.
+1. The `lockfile` method in the Gemfile.
+1. The default behavior of adding `.lock` to the end of the Gemfile name.
diff --git a/lib/bundler/man/index.txt b/lib/bundler/man/index.txt
new file mode 100644
index 0000000000..f610ba852a
--- /dev/null
+++ b/lib/bundler/man/index.txt
@@ -0,0 +1,31 @@
+Gemfile(5)            gemfile.5
+bundle(1)             bundle.1
+bundle-add(1)         bundle-add.1
+bundle-binstubs(1)    bundle-binstubs.1
+bundle-cache(1)       bundle-cache.1
+bundle-check(1)       bundle-check.1
+bundle-clean(1)       bundle-clean.1
+bundle-config(1)      bundle-config.1
+bundle-console(1)     bundle-console.1
+bundle-doctor(1)      bundle-doctor.1
+bundle-env(1)         bundle-env.1
+bundle-exec(1)        bundle-exec.1
+bundle-fund(1)        bundle-fund.1
+bundle-gem(1)         bundle-gem.1
+bundle-help(1)        bundle-help.1
+bundle-info(1)        bundle-info.1
+bundle-init(1)        bundle-init.1
+bundle-install(1)     bundle-install.1
+bundle-issue(1)       bundle-issue.1
+bundle-licenses(1)    bundle-licenses.1
+bundle-list(1)        bundle-list.1
+bundle-lock(1)        bundle-lock.1
+bundle-open(1)        bundle-open.1
+bundle-outdated(1)    bundle-outdated.1
+bundle-platform(1)    bundle-platform.1
+bundle-plugin(1)      bundle-plugin.1
+bundle-pristine(1)    bundle-pristine.1
+bundle-remove(1)      bundle-remove.1
+bundle-show(1)        bundle-show.1
+bundle-update(1)      bundle-update.1
+bundle-version(1)     bundle-version.1
diff --git a/lib/bundler/match_metadata.rb b/lib/bundler/match_metadata.rb
new file mode 100644
index 0000000000..92aeb2e893
--- /dev/null
+++ b/lib/bundler/match_metadata.rb
@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+module Bundler
+  module MatchMetadata
+    def matches_current_metadata?
+      matches_current_ruby? && matches_current_rubygems?
+    end
+
+    def matches_current_ruby?
+      @required_ruby_version.satisfied_by?(Gem.ruby_version)
+    end
+
+    def matches_current_rubygems?
+      @required_rubygems_version.satisfied_by?(Gem.rubygems_version)
+    end
+
+    def matches_current_metadata_with_overrides?(overrides)
+      matches_current_ruby_with_overrides?(overrides) && matches_current_rubygems_with_overrides?(overrides)
+    end
+
+    def matches_current_ruby_with_overrides?(overrides)
+      effective_required_version(@required_ruby_version, :required_ruby_version, overrides).satisfied_by?(Gem.ruby_version)
+    end
+
+    def matches_current_rubygems_with_overrides?(overrides)
+      effective_required_version(@required_rubygems_version, :required_rubygems_version, overrides).satisfied_by?(Gem.rubygems_version)
+    end
+
+    def expanded_dependencies
+      runtime_dependencies + [
+        metadata_dependency("Ruby", @required_ruby_version),
+        metadata_dependency("RubyGems", @required_rubygems_version),
+      ].compact
+    end
+
+    def metadata_dependency(name, requirement)
+      return if requirement.nil? || requirement.none?
+
+      Gem::Dependency.new("#{name}\0", requirement)
+    end
+
+    private
+
+    def effective_required_version(requirement, field, overrides)
+      return requirement if overrides.nil? || overrides.empty?
+      override = Override.find_for(overrides, name, field)
+      override ? override.apply_to(requirement) : requirement
+    end
+  end
+end
diff --git a/lib/bundler/match_platform.rb b/lib/bundler/match_platform.rb
new file mode 100644
index 0000000000..479818e5ec
--- /dev/null
+++ b/lib/bundler/match_platform.rb
@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+module Bundler
+  module MatchPlatform
+    def installable_on_platform?(target_platform) # :nodoc:
+      return true if [Gem::Platform::RUBY, nil, target_platform].include?(platform)
+      return true if Gem::Platform.new(platform) === target_platform
+
+      false
+    end
+
+    def self.select_best_platform_match(specs, platform, force_ruby: false, prefer_locked: false)
+      matching = select_all_platform_match(specs, platform, force_ruby: force_ruby, prefer_locked: prefer_locked)
+
+      Gem::Platform.sort_and_filter_best_platform_match(matching, platform)
+    end
+
+    def self.select_best_local_platform_match(specs, force_ruby: false)
+      local = Bundler.local_platform
+      matching = select_all_platform_match(specs, local, force_ruby: force_ruby).filter_map(&:materialized_for_installation)
+
+      Gem::Platform.sort_best_platform_match(matching, local)
+    end
+
+    def self.select_all_platform_match(specs, platform, force_ruby: false, prefer_locked: false)
+      matching = specs.select {|spec| spec.installable_on_platform?(force_ruby ? Gem::Platform::RUBY : platform) }
+
+      specs.each(&:force_ruby_platform!) if force_ruby
+
+      if prefer_locked
+        locked_originally = matching.select {|spec| spec.is_a?(::Bundler::LazySpecification) }
+        return locked_originally if locked_originally.any?
+      end
+
+      matching
+    end
+
+    def self.generic_local_platform_is_ruby?
+      Bundler.generic_local_platform == Gem::Platform::RUBY
+    end
+  end
+end
diff --git a/lib/bundler/match_remote_metadata.rb b/lib/bundler/match_remote_metadata.rb
new file mode 100644
index 0000000000..601af7e55d
--- /dev/null
+++ b/lib/bundler/match_remote_metadata.rb
@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+module Bundler
+  module FetchMetadata
+    # A fallback is included because the original version of the specification
+    # API didn't include that field, so some marshalled specs in the index have it
+    # set to +nil+.
+    def matches_current_ruby?
+      ensure_required_ruby_version_loaded
+      super
+    end
+
+    def matches_current_rubygems?
+      ensure_required_rubygems_version_loaded
+      super
+    end
+
+    def matches_current_ruby_with_overrides?(overrides)
+      ensure_required_ruby_version_loaded
+      super
+    end
+
+    def matches_current_rubygems_with_overrides?(overrides)
+      ensure_required_rubygems_version_loaded
+      super
+    end
+
+    private
+
+    def ensure_required_ruby_version_loaded
+      @required_ruby_version ||= _remote_specification.required_ruby_version || Gem::Requirement.default # rubocop:disable Naming/MemoizedInstanceVariableName
+    end
+
+    def ensure_required_rubygems_version_loaded
+      @required_rubygems_version ||= _remote_specification.required_rubygems_version || Gem::Requirement.default # rubocop:disable Naming/MemoizedInstanceVariableName
+    end
+  end
+
+  module MatchRemoteMetadata
+    include MatchMetadata
+
+    prepend FetchMetadata
+  end
+end
diff --git a/lib/bundler/materialization.rb b/lib/bundler/materialization.rb
new file mode 100644
index 0000000000..82e48464a7
--- /dev/null
+++ b/lib/bundler/materialization.rb
@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+module Bundler
+  #
+  # This class materializes a set of resolved specifications (`LazySpecification`)
+  # for a given gem into the most appropriate real specifications
+  # (`StubSepecification`, `EndpointSpecification`, etc), given a dependency and a
+  # target platform.
+  #
+  class Materialization
+    def initialize(dep, platform, candidates:)
+      @dep = dep
+      @platform = platform
+      @candidates = candidates
+    end
+
+    def complete?
+      specs.any?
+    end
+
+    def specs
+      @specs ||= if @candidates.nil?
+        []
+      elsif platform
+        MatchPlatform.select_best_platform_match(@candidates, platform, force_ruby: dep.force_ruby_platform)
+      else
+        MatchPlatform.select_best_local_platform_match(@candidates, force_ruby: dep.force_ruby_platform || dep.default_force_ruby_platform)
+      end
+    end
+
+    def dependencies
+      (materialized_spec || specs.first).runtime_dependencies.map {|d| [d, platform] }
+    end
+
+    def materialized_spec
+      specs.reject(&:missing?).first&.materialization
+    end
+
+    def completely_missing_specs
+      return [] unless specs.all?(&:missing?)
+
+      specs
+    end
+
+    def partially_missing_specs
+      specs.select(&:missing?)
+    end
+
+    def incomplete_specs
+      return [] if complete?
+
+      @candidates || LazySpecification.new(dep.name, nil, nil)
+    end
+
+    private
+
+    attr_reader :dep, :platform
+  end
+end
diff --git a/lib/bundler/mirror.rb b/lib/bundler/mirror.rb
new file mode 100644
index 0000000000..494a6d6aef
--- /dev/null
+++ b/lib/bundler/mirror.rb
@@ -0,0 +1,221 @@
+# frozen_string_literal: true
+
+require "socket"
+
+module Bundler
+  class Settings
+    # Class used to build the mirror set and then find a mirror for a given URI
+    #
+    # @param prober [Prober object, nil] by default a TCPSocketProbe, this object
+    #   will be used to probe the mirror address to validate that the mirror replies.
+    class Mirrors
+      def initialize(prober = nil)
+        @all = Mirror.new
+        @prober = prober || TCPSocketProbe.new
+        @mirrors = {}
+      end
+
+      # Returns a mirror for the given uri.
+      #
+      # Depending on the uri having a valid mirror or not, it may be a
+      #   mirror that points to the provided uri
+      def for(uri)
+        if @all.validate!(@prober).valid?
+          @all
+        else
+          fetch_valid_mirror_for(Settings.normalize_uri(uri))
+        end
+      end
+
+      def each
+        @mirrors.each do |k, v|
+          yield k, v.uri.to_s
+        end
+      end
+
+      def parse(key, value)
+        config = MirrorConfig.new(key, value)
+        mirror = if config.all?
+          @all
+        else
+          @mirrors[config.uri] ||= Mirror.new
+        end
+        config.update_mirror(mirror)
+      end
+
+      private
+
+      def fetch_valid_mirror_for(uri)
+        downcased = uri.to_s.downcase
+        mirror = @mirrors[downcased] || @mirrors[Gem::URI(downcased).host] || Mirror.new(uri)
+        mirror.validate!(@prober)
+        mirror = Mirror.new(uri) unless mirror.valid?
+        mirror
+      end
+    end
+
+    # A mirror
+    #
+    # Contains both the uri that should be used as a mirror and the
+    #   fallback timeout which will be used for probing if the mirror
+    #   replies on time or not.
+    class Mirror
+      DEFAULT_FALLBACK_TIMEOUT = 0.1
+
+      attr_reader :uri, :fallback_timeout
+
+      def initialize(uri = nil, fallback_timeout = 0)
+        self.uri = uri
+        self.fallback_timeout = fallback_timeout
+        @valid = nil
+      end
+
+      def uri=(uri)
+        @uri = if uri.nil?
+          nil
+        else
+          Gem::URI(uri.to_s)
+        end
+        @valid = nil
+      end
+
+      def fallback_timeout=(timeout)
+        case timeout
+        when true, "true"
+          @fallback_timeout = DEFAULT_FALLBACK_TIMEOUT
+        when false, "false"
+          @fallback_timeout = 0
+        else
+          @fallback_timeout = timeout.to_i
+        end
+        @valid = nil
+      end
+
+      def ==(other)
+        !other.nil? && uri == other.uri && fallback_timeout == other.fallback_timeout
+      end
+
+      def valid?
+        return false if @uri.nil?
+        return @valid unless @valid.nil?
+        false
+      end
+
+      def validate!(probe = nil)
+        @valid = false if uri.nil?
+        if @valid.nil?
+          @valid = fallback_timeout == 0 || (probe || TCPSocketProbe.new).replies?(self)
+        end
+        self
+      end
+    end
+
+    # Class used to parse one configuration line
+    #
+    # Gets the configuration line and the value.
+    #   This object provides a `update_mirror` method
+    #   used to setup the given mirror value.
+    class MirrorConfig
+      attr_accessor :uri, :value
+
+      def initialize(config_line, value)
+        uri, fallback =
+          config_line.match(%r{\Amirror\.(all|.+?)(\.fallback_timeout)?\/?\z}).captures
+        @fallback = !fallback.nil?
+        @all = false
+        if uri == "all"
+          @all = true
+        else
+          @uri = Gem::URI(uri).absolute? ? Settings.normalize_uri(uri) : uri
+        end
+        @value = value
+      end
+
+      def all?
+        @all
+      end
+
+      def update_mirror(mirror)
+        if @fallback
+          mirror.fallback_timeout = @value
+        else
+          mirror.uri = Settings.normalize_uri(@value)
+        end
+      end
+    end
+
+    # Class used for probing TCP availability for a given mirror.
+    class TCPSocketProbe
+      def replies?(mirror)
+        MirrorSockets.new(mirror).any? do |socket, address, timeout|
+          socket.connect_nonblock(address)
+        rescue Errno::EINPROGRESS
+          wait_for_writtable_socket(socket, address, timeout)
+        rescue RuntimeError # Connection failed somehow, again
+          false
+        end
+      end
+
+      private
+
+      def wait_for_writtable_socket(socket, address, timeout)
+        if IO.select(nil, [socket], nil, timeout)
+          probe_writtable_socket(socket, address)
+        else # TCP Handshake timed out, or there is something dropping packets
+          false
+        end
+      end
+
+      def probe_writtable_socket(socket, address)
+        socket.connect_nonblock(address)
+      rescue Errno::EISCONN
+        true
+      rescue StandardError # Connection failed
+        false
+      end
+    end
+  end
+
+  # Class used to build the list of sockets that correspond to
+  #   a given mirror.
+  #
+  # One mirror may correspond to many different addresses, both
+  #   because of it having many dns entries or because
+  #   the network interface is both ipv4 and ipv5
+  class MirrorSockets
+    def initialize(mirror)
+      @timeout = mirror.fallback_timeout
+      @addresses = Socket.getaddrinfo(mirror.uri.host, mirror.uri.port).map do |address|
+        SocketAddress.new(address[0], address[3], address[1])
+      end
+    end
+
+    def any?
+      @addresses.any? do |address|
+        socket = Socket.new(Socket.const_get(address.type), Socket::SOCK_STREAM, 0)
+        socket.setsockopt(Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1)
+        value = yield socket, address.to_socket_address, @timeout
+        socket.close unless socket.closed?
+        value
+      end
+    end
+  end
+
+  # Socket address builder.
+  #
+  # Given a socket type, a host and a port,
+  #   provides a method to build sockaddr string
+  class SocketAddress
+    attr_reader :type, :host, :port
+
+    def initialize(type, host, port)
+      @type = type
+      @host = host
+      @port = port
+    end
+
+    def to_socket_address
+      Socket.pack_sockaddr_in(@port, @host)
+    end
+  end
+end
diff --git a/lib/bundler/override.rb b/lib/bundler/override.rb
new file mode 100644
index 0000000000..0e0ec59fd7
--- /dev/null
+++ b/lib/bundler/override.rb
@@ -0,0 +1,69 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Override
+    UPPER_BOUND_OPERATORS = ["<", "<="].freeze
+
+    def self.find_for(overrides, name, field)
+      overrides.find {|o| o.target == name && o.field == field } ||
+        overrides.find {|o| o.target == :all && o.field == field }
+    end
+
+    # Attach the given overrides onto every LazySpecification in `specs` so
+    # downstream consumers (LazySpecification#choose_compatible, the install-
+    # time compatibility check, etc.) can read the override list off the spec
+    # itself. Non-LazySpec entries (StubSpecification, Gem::Specification, ...)
+    # are left untouched.
+    def self.attach(specs, overrides)
+      return if overrides.nil? || overrides.empty?
+      specs.each {|s| s.overrides = overrides if s.is_a?(LazySpecification) }
+    end
+
+    attr_reader :target, :field, :operation, :source_location
+
+    def initialize(target, field, operation, source_location: nil)
+      @target = target
+      @field = field
+      @operation = operation
+      @source_location = source_location
+    end
+
+    def source_location_label
+      return nil unless @source_location
+      "#{File.basename(@source_location.path)}:#{@source_location.lineno}"
+    end
+
+    def apply_to(requirement)
+      case operation
+      when nil
+        Gem::Requirement.default
+      when :ignore_upper
+        remove_upper_bounds(requirement)
+      when String
+        Gem::Requirement.new(operation)
+      else
+        raise ArgumentError, "unsupported override operation: #{operation.inspect}"
+      end
+    end
+
+    private
+
+    def remove_upper_bounds(requirement)
+      return Gem::Requirement.default if requirement.nil? || requirement.none?
+
+      preserved = requirement.requirements.filter_map do |op, version|
+        if UPPER_BOUND_OPERATORS.include?(op)
+          nil
+        elsif op == "~>"
+          [">=", version]
+        else
+          [op, version]
+        end
+      end
+
+      return Gem::Requirement.default if preserved.empty?
+
+      Gem::Requirement.new(preserved.map {|op, v| "#{op} #{v}" })
+    end
+  end
+end
diff --git a/lib/bundler/plugin.rb b/lib/bundler/plugin.rb
new file mode 100644
index 0000000000..faca6bea53
--- /dev/null
+++ b/lib/bundler/plugin.rb
@@ -0,0 +1,381 @@
+# frozen_string_literal: true
+
+require_relative "plugin/api"
+
+module Bundler
+  module Plugin
+    autoload :DSL,        File.expand_path("plugin/dsl", __dir__)
+    autoload :Events,     File.expand_path("plugin/events", __dir__)
+    autoload :Index,      File.expand_path("plugin/index", __dir__)
+    autoload :Installer,  File.expand_path("plugin/installer", __dir__)
+    autoload :SourceList, File.expand_path("plugin/source_list", __dir__)
+
+    class MalformattedPlugin < PluginError; end
+    class UndefinedCommandError < PluginError; end
+    class UnknownSourceError < PluginError; end
+    class PluginInstallError < PluginError; end
+
+    PLUGIN_FILE_NAME = "plugins.rb"
+
+    module_function
+
+    def reset!
+      instance_variables.each {|i| remove_instance_variable(i) }
+
+      @sources = {}
+      @commands = {}
+      @hooks_by_event = Hash.new {|h, k| h[k] = [] }
+      @loaded_plugin_names = []
+    end
+
+    reset!
+
+    # Installs a new plugin by the given name
+    #
+    # @param [Array<String>] names the name of plugin to be installed
+    # @param [Hash] options various parameters as described in description.
+    #               Refer to cli/plugin for available options
+    def install(names, options)
+      raise InvalidOption, "You cannot specify `--branch` and `--ref` at the same time." if options["branch"] && options["ref"]
+
+      specs = Installer.new.install(names, options)
+
+      save_plugins names, specs
+    rescue PluginError
+      specs_to_delete = specs.select {|k, _v| names.include?(k) && !index.commands.values.include?(k) }
+      specs_to_delete.each_value {|spec| Bundler.rm_rf(spec.full_gem_path) }
+
+      raise
+    end
+
+    # Uninstalls plugins by the given names
+    #
+    # @param [Array<String>] names the names of plugins to be uninstalled
+    def uninstall(names, options)
+      if names.empty? && !options[:all]
+        Bundler.ui.error "No plugins to uninstall. Specify at least 1 plugin to uninstall.\n"\
+          "Use --all option to uninstall all the installed plugins."
+        return
+      end
+
+      names = index.installed_plugins if options[:all]
+      if names.any?
+        names.each do |name|
+          if index.installed?(name)
+            path = index.plugin_path(name).to_s
+            Bundler.rm_rf(path) if index.installed_in_plugin_root?(name)
+            index.unregister_plugin(name)
+            Bundler.ui.info "Uninstalled plugin #{name}"
+          else
+            Bundler.ui.error "Plugin #{name} is not installed \n"
+          end
+        end
+      else
+        Bundler.ui.info "No plugins installed"
+      end
+    end
+
+    # List installed plugins and commands
+    #
+    def list
+      installed_plugins = index.installed_plugins
+      if installed_plugins.any?
+        output = String.new
+        installed_plugins.each do |plugin|
+          output << "#{plugin}\n"
+          output << "-----\n"
+          index.plugin_commands(plugin).each do |command|
+            output << "  #{command}\n"
+          end
+          output << "\n"
+        end
+      else
+        output = "No plugins installed"
+      end
+      Bundler.ui.info output
+    end
+
+    # Evaluates the Gemfile with a limited DSL and installs the plugins
+    # specified by plugin method
+    #
+    # @param [Pathname] gemfile path
+    # @param [Proc] block that can be evaluated for (inline) Gemfile
+    def gemfile_install(gemfile = nil, &inline)
+      Bundler.settings.temporary(frozen: false, deployment: false) do
+        builder = DSL.new
+        if block_given?
+          builder.instance_eval(&inline)
+        else
+          builder.eval_gemfile(gemfile)
+        end
+        builder.check_primary_source_safety
+        definition = builder.to_definition(nil, true)
+
+        return if definition.dependencies.empty?
+
+        plugins = definition.dependencies.map(&:name)
+        installed_specs = Installer.new.install_definition(definition)
+
+        save_plugins plugins, installed_specs, builder.inferred_plugins
+      end
+    rescue RuntimeError => e
+      unless e.is_a?(GemfileError)
+        Bundler.ui.error "Failed to install plugin: #{e.message}\n  #{e.backtrace[0]}"
+      end
+      raise
+    end
+
+    # The index object used to store the details about the plugin
+    def index
+      @index ||= Index.new
+    end
+
+    # The directory root for all plugin related data
+    #
+    # If run in an app, points to local root, in app_config_path
+    # Otherwise, points to global root, in Bundler.user_bundle_path("plugin")
+    def root
+      @root ||= if SharedHelpers.in_bundle?
+        local_root
+      else
+        global_root
+      end
+    end
+
+    def local_root
+      Bundler.app_config_path.join("plugin")
+    end
+
+    # The global directory root for all plugin related data
+    def global_root
+      Bundler.user_bundle_path("plugin")
+    end
+
+    # The cache directory for plugin stuffs
+    def cache
+      @cache ||= root.join("cache")
+    end
+
+    # To be called via the API to register to handle a command
+    def add_command(command, cls)
+      @commands[command] = cls
+    end
+
+    # Checks if any plugin handles the command
+    def command?(command)
+      !index.command_plugin(command).nil?
+    end
+
+    # To be called from Cli class to pass the command and argument to
+    # appropriate plugin class
+    def exec_command(command, args)
+      raise UndefinedCommandError, "Command `#{command}` not found" unless command? command
+
+      load_plugin index.command_plugin(command) unless @commands.key? command
+
+      @commands[command].new.exec(command, args)
+    end
+
+    # To be called via the API to register to handle a source plugin
+    def add_source(source, cls)
+      @sources[source] = cls
+    end
+
+    # Checks if any plugin declares the source
+    def source?(name)
+      !index.source_plugin(name.to_s).nil?
+    end
+
+    # @return [Class] that handles the source. The class includes API::Source
+    def source(name)
+      raise UnknownSourceError, "Source #{name} not found" unless source? name
+
+      load_plugin(index.source_plugin(name)) unless @sources.key? name
+
+      @sources[name]
+    end
+
+    # @param [Hash] The options that are present in the lockfile
+    # @return [API::Source] the instance of the class that handles the source
+    #                       type passed in locked_opts
+    def from_lock(locked_opts)
+      src = source(locked_opts["type"])
+
+      src.new(locked_opts.merge("uri" => locked_opts["remote"]))
+    end
+
+    # To be called via the API to register a hooks and corresponding block that
+    # will be called to handle the hook
+    def add_hook(event, &block)
+      unless Events.defined_event?(event)
+        raise ArgumentError, "Event '#{event}' not defined in Bundler::Plugin::Events"
+      end
+      @hooks_by_event[event.to_s] << block
+    end
+
+    # Runs all the hooks that are registered for the passed event
+    #
+    # It passes the passed arguments and block to the block registered with
+    # the api.
+    #
+    # @param [String] event
+    def hook(event, *args, &arg_blk)
+      return unless Bundler.settings[:plugins]
+      unless Events.defined_event?(event)
+        raise ArgumentError, "Event '#{event}' not defined in Bundler::Plugin::Events"
+      end
+
+      plugins = index.hook_plugins(event)
+      return unless plugins.any?
+
+      plugins.each {|name| load_plugin(name) }
+
+      @hooks_by_event[event].each {|blk| blk.call(*args, &arg_blk) }
+    end
+
+    # currently only intended for specs
+    #
+    # @return [String, nil] installed path
+    def installed?(plugin)
+      Index.new.installed?(plugin)
+    end
+
+    # @return [true, false] whether the plugin is loaded
+    def loaded?(plugin)
+      @loaded_plugin_names.include?(plugin)
+    end
+
+    # Post installation processing and registering with index
+    #
+    # @param [Array<String>] plugins list to be installed
+    # @param [Hash] specs of plugins mapped to installation path (currently they
+    #               contain all the installed specs, including plugins)
+    # @param [Array<String>] names of inferred source plugins that can be ignored
+    def save_plugins(plugins, specs, optional_plugins = [])
+      plugins.each do |name|
+        spec = specs[name]
+
+        # It's possible that the `plugin` found in the Gemfile don't appear in the specs. For instance when
+        # calling `BUNDLE_WITHOUT=default bundle install`, the plugins will not get installed.
+        next if spec.nil?
+        next if index.up_to_date?(spec)
+
+        save_plugin(name, spec, optional_plugins.include?(name))
+      end
+    end
+
+    # Checks if the gem is good to be a plugin
+    #
+    # At present it only checks whether it contains plugins.rb file
+    #
+    # @param [Pathname] plugin_path the path plugin is installed at
+    # @raise [MalformattedPlugin] if plugins.rb file is not found
+    def validate_plugin!(plugin_path)
+      plugin_file = plugin_path.join(PLUGIN_FILE_NAME)
+      raise MalformattedPlugin, "#{PLUGIN_FILE_NAME} was not found in the plugin." unless plugin_file.file?
+    end
+
+    # Validates and registers a plugin.
+    #
+    # @param [String] name the name of the plugin
+    # @param [Specification] spec of installed plugin
+    # @param [Boolean] optional_plugin, removed if there is conflict with any
+    #                     other plugin (used for default source plugins)
+    #
+    # @raise [PluginInstallError] if validation or registration raises any error
+    def save_plugin(name, spec, optional_plugin = false)
+      validate_plugin! Pathname.new(spec.full_gem_path)
+      installed = register_plugin(name, spec, optional_plugin)
+      Bundler.ui.info "Installed plugin #{name}" if installed
+    rescue PluginError => e
+      raise PluginInstallError, "Failed to install plugin `#{spec.name}`, due to #{e.class} (#{e.message})"
+    end
+
+    # Runs the plugins.rb file in an isolated namespace, records the plugin
+    # actions it registers for and then passes the data to index to be stored.
+    #
+    # @param [String] name the name of the plugin
+    # @param [Specification] spec of installed plugin
+    # @param [Boolean] optional_plugin, removed if there is conflict with any
+    #                     other plugin (used for default source plugins)
+    #
+    # @raise [MalformattedPlugin] if plugins.rb raises any error
+    def register_plugin(name, spec, optional_plugin = false)
+      commands = @commands
+      sources = @sources
+      hooks = @hooks_by_event
+
+      @commands = {}
+      @sources = {}
+      @hooks_by_event = Hash.new {|h, k| h[k] = [] }
+
+      load_paths = spec.load_paths
+      Gem.add_to_load_path(*load_paths)
+      path = Pathname.new spec.full_gem_path
+
+      begin
+        load path.join(PLUGIN_FILE_NAME), true
+      rescue StandardError => e
+        raise MalformattedPlugin, "#{e.class}: #{e.message}"
+      end
+
+      if optional_plugin && @sources.keys.any? {|s| source? s }
+        Bundler.rm_rf(path)
+        false
+      else
+        index.register_plugin(name, path.to_s, load_paths, @commands.keys,
+          @sources.keys, @hooks_by_event.keys)
+        true
+      end
+    ensure
+      @commands = commands
+      @sources = sources
+      @hooks_by_event = hooks
+    end
+
+    # Executes the plugins.rb file
+    #
+    # @param [String] name of the plugin
+    def load_plugin(name)
+      return unless name && !name.empty?
+      return if loaded?(name)
+
+      # Need to ensure before this that plugin root where the rest of gems
+      # are installed to be on load path to support plugin deps. Currently not
+      # done to avoid conflicts
+      path = index.plugin_path(name)
+
+      paths = index.load_paths(name)
+      invalid_paths = paths.reject {|p| File.directory?(p) }
+
+      if invalid_paths.any?
+        Bundler.ui.warn <<~MESSAGE
+          The following plugin paths don't exist: #{invalid_paths.join(", ")}.
+
+          This can happen if the plugin was installed with a different version of Ruby that has since been uninstalled.
+
+          If you would like to reinstall the plugin, run:
+
+          bundler plugin uninstall #{name} && bundler plugin install #{name}
+
+          Continuing without installing plugin #{name}.
+        MESSAGE
+
+        return
+      end
+
+      Gem.add_to_load_path(*paths)
+
+      load path.join(PLUGIN_FILE_NAME)
+
+      @loaded_plugin_names << name
+    rescue RuntimeError => e
+      Bundler.ui.error "Failed loading plugin #{name}: #{e.message}"
+      raise
+    end
+
+    class << self
+      private :load_plugin, :register_plugin, :save_plugins, :validate_plugin!
+    end
+  end
+end
diff --git a/lib/bundler/plugin/api.rb b/lib/bundler/plugin/api.rb
new file mode 100644
index 0000000000..ee2bffe3ab
--- /dev/null
+++ b/lib/bundler/plugin/api.rb
@@ -0,0 +1,81 @@
+# frozen_string_literal: true
+
+module Bundler
+  # This is the interfacing class represents the API that we intend to provide
+  # the plugins to use.
+  #
+  # For plugins to be independent of the Bundler internals they shall limit their
+  # interactions to methods of this class only. This will save them from breaking
+  # when some internal change.
+  #
+  # Currently we are delegating the methods defined in Bundler class to
+  # itself. So, this class acts as a buffer.
+  #
+  # If there is some change in the Bundler class that is incompatible to its
+  # previous behavior or if otherwise desired, we can reimplement(or implement)
+  # the method to preserve compatibility.
+  #
+  # To use this, either the class can inherit this class or use it directly.
+  # For example of both types of use, refer the file `spec/plugins/command.rb`
+  #
+  # To use it without inheriting, you will have to create an object of this
+  # to use the functions (except for declaration functions like command, source,
+  # and hooks).
+  module Plugin
+    class API
+      autoload :Source, File.expand_path("api/source", __dir__)
+
+      # The plugins should declare that they handle a command through this helper.
+      #
+      # @param [String] command being handled by them
+      # @param [Class] (optional) class that handles the command. If not
+      #                 provided, the `self` class will be used.
+      def self.command(command, cls = self)
+        Plugin.add_command command, cls
+      end
+
+      # The plugins should declare that they provide a installation source
+      # through this helper.
+      #
+      # @param [String] the source type they provide
+      # @param [Class] (optional) class that handles the source. If not
+      #                 provided, the `self` class will be used.
+      def self.source(source, cls = self)
+        cls.send :include, Bundler::Plugin::API::Source
+        Plugin.add_source source, cls
+      end
+
+      def self.hook(event, &block)
+        Plugin.add_hook(event, &block)
+      end
+
+      # The cache dir to be used by the plugins for storage
+      #
+      # @return [Pathname] path of the cache dir
+      def cache_dir
+        Plugin.cache.join("plugins")
+      end
+
+      # A tmp dir to be used by plugins
+      # Accepts names that get concatenated as suffix
+      #
+      # @return [Pathname] object for the new directory created
+      def tmp(*names)
+        Bundler.tmp(["plugin", *names].join("-"))
+      end
+
+      def method_missing(name, *args, &blk)
+        return Bundler.send(name, *args, &blk) if Bundler.respond_to?(name)
+
+        return SharedHelpers.send(name, *args, &blk) if SharedHelpers.respond_to?(name)
+
+        super
+      end
+
+      def respond_to_missing?(name, include_private = false)
+        SharedHelpers.respond_to?(name, include_private) ||
+          Bundler.respond_to?(name, include_private) || super
+      end
+    end
+  end
+end
diff --git a/lib/bundler/plugin/api/source.rb b/lib/bundler/plugin/api/source.rb
new file mode 100644
index 0000000000..798326673a
--- /dev/null
+++ b/lib/bundler/plugin/api/source.rb
@@ -0,0 +1,330 @@
+# frozen_string_literal: true
+
+module Bundler
+  module Plugin
+    class API
+      # This class provides the base to build source plugins
+      # All the method here are required to build a source plugin (except
+      # `uri_hash`, `gem_install_dir`; they are helpers).
+      #
+      # Defaults for methods, where ever possible are provided which is
+      # expected to work. But, all source plugins have to override
+      # `fetch_gemspec_files` and `install`. Defaults are also not provided for
+      # `remote!`, `cache!` and `unlock!`.
+      #
+      # The defaults shall work for most situations but nevertheless they can
+      # be (preferably should be) overridden as per the plugins' needs safely
+      # (as long as they behave as expected).
+      # On overriding `initialize` you should call super first.
+      #
+      # If required plugin should override `hash`, `==` and `eql?` methods to be
+      # able to match objects representing same sources, but may be created in
+      # different situation (like form gemfile and lockfile). The default ones
+      # checks only for class and uri, but elaborate source plugins may need
+      # more comparisons (e.g. git checking on branch or tag).
+      #
+      # @!attribute [r] uri
+      #   @return [String] the remote specified with `source` block in Gemfile
+      #
+      # @!attribute [r] options
+      #   @return [String] options passed during initialization (either from
+      #     lockfile or Gemfile)
+      #
+      # @!attribute [r] name
+      #   @return [String] name that can be used to uniquely identify a source
+      #
+      # @!attribute [rw] dependency_names
+      #   @return [Array<String>] Names of dependencies that the source should
+      #     try to resolve. It is not necessary to use this list internally. This
+      #     is present to be compatible with `Definition` and is used by
+      #     rubygems source.
+      module Source
+        attr_reader :uri, :options, :name, :checksum_store
+        attr_accessor :dependency_names
+
+        def initialize(opts)
+          @options = opts
+          @dependency_names = []
+          @uri = opts["uri"]
+          @type = opts["type"]
+          @name = opts["name"] || "#{@type} at #{@uri}"
+          @checksum_store = Checksum::Store.new
+        end
+
+        # This is used by the default `spec` method to constructs the
+        # Specification objects for the gems and versions that can be installed
+        # by this source plugin.
+        #
+        # Note: If the spec method is overridden, this function is not necessary
+        #
+        # @return [Array<String>] paths of the gemspec files for gems that can
+        #                         be installed
+        def fetch_gemspec_files
+          []
+        end
+
+        # Options to be saved in the lockfile so that the source plugin is able
+        # to check out same version of gem later.
+        #
+        # There options are passed when the source plugin is created from the
+        # lockfile.
+        #
+        # @return [Hash]
+        def options_to_lock
+          {}
+        end
+
+        # Download the gem specified by the spec at appropriate path.
+        #
+        # A source plugin can implement this method to split the download and the
+        # installation of a gem.
+        #
+        # @return [Boolean] Whether the download of the gem succeeded.
+        def download(spec, opts); end
+
+        # Install the gem specified by the spec at appropriate path.
+        # `install_path` provides a sufficient default, if the source can only
+        # satisfy one gem,  but is not binding.
+        #
+        # @return [String] post installation message (if any)
+        def install(spec, opts)
+          raise MalformattedPlugin, "Source plugins need to override the install method."
+        end
+
+        # It builds extensions, generates bins and installs them for the spec
+        # provided.
+        #
+        # It depends on `spec.loaded_from` to get full_gem_path. The source
+        # plugins should set that.
+        #
+        # It should be called in `install` after the plugin is done placing the
+        # gem at correct install location.
+        #
+        # It also runs Gem hooks `pre_install`, `post_build` and `post_install`
+        #
+        # Note: Do not override if you don't know what you are doing.
+        def post_install(spec, disable_exts = false)
+          opts = { env_shebang: false, disable_extensions: disable_exts }
+          installer = Bundler::Source::Path::Installer.new(spec, opts)
+          installer.post_install
+        end
+
+        # A default installation path to install a single gem. If the source
+        # servers multiple gems, it's not of much use and the source should one
+        # of its own.
+        def install_path
+          @install_path ||=
+            begin
+              base_name = File.basename(Gem::URI.parse(uri).normalize.path)
+
+              gem_install_dir.join("#{base_name}-#{uri_hash[0..11]}")
+            end
+        end
+
+        # Parses the gemspec files to find the specs for the gems that can be
+        # satisfied by the source.
+        #
+        # Few important points to keep in mind:
+        #   - If the gems are not installed then it shall return specs for all
+        #   the gems it can satisfy
+        #   - If gem is installed (that is to be detected by the plugin itself)
+        #   then it shall return at least the specs that are installed.
+        #   - The `loaded_from` for each of the specs shall be correct (it is
+        #   used to find the load path)
+        #
+        # @return [Bundler::Index] index containing the specs
+        def specs
+          files = fetch_gemspec_files
+
+          Bundler::Index.build do |index|
+            files.each do |file|
+              next unless spec = Bundler.load_gemspec(file)
+              spec.installed_by_version = Gem::VERSION
+
+              spec.source = self
+              Bundler.rubygems.validate(spec)
+
+              index << spec
+            end
+          end
+        end
+
+        # Set internal representation to fetch the gems/specs locally.
+        #
+        # When this is called, the source should try to fetch the specs and
+        # install from the local system.
+        def local!
+        end
+
+        # Set internal representation to fetch the gems/specs from remote.
+        #
+        # When this is called, the source should try to fetch the specs and
+        # install from remote path.
+        def remote!
+        end
+
+        # Set internal representation to fetch the gems/specs from app cache.
+        #
+        # When this is called, the source should try to fetch the specs and
+        # install from the path provided by `app_cache_path`.
+        def cached!
+        end
+
+        # This is called to update the spec and installation.
+        #
+        # If the source plugin is loaded from lockfile or otherwise, it shall
+        # refresh the cache/specs (e.g. git sources can make a fresh clone).
+        def unlock!
+        end
+
+        # Name of directory where plugin the is expected to cache the gems when
+        # #cache is called.
+        #
+        # Also this name is matched against the directories in cache for pruning
+        #
+        # This is used by `app_cache_path`
+        def app_cache_dirname
+          base_name = File.basename(Gem::URI.parse(uri).normalize.path)
+          "#{base_name}-#{uri_hash}"
+        end
+
+        # This method is called while caching to save copy of the gems that the
+        # source can resolve to path provided by `app_cache_app`so that they can
+        # be reinstalled from the cache without querying the remote (i.e. an
+        # alternative to remote)
+        #
+        # This is stored with the app and source plugins should try to provide
+        # specs and install only from this cache when `cached!` is called.
+        #
+        # This cache is different from the internal caching that can be done
+        # at sub paths of `cache_path` (from API). This can be though as caching
+        # by bundler.
+        def cache(spec, custom_path = nil)
+          new_cache_path = app_cache_path(custom_path)
+
+          FileUtils.rm_rf(new_cache_path)
+          FileUtils.cp_r(install_path, new_cache_path)
+          FileUtils.rm_rf(app_cache_path.join(".git"))
+          FileUtils.touch(app_cache_path.join(".bundlecache"))
+        end
+
+        # This shall check if two source object represent the same source.
+        #
+        # The comparison shall take place only on the attribute that can be
+        # inferred from the options passed from Gemfile and not on attributes
+        # that are used to pin down the gem to specific version (e.g. Git
+        # sources should compare on branch and tag but not on commit hash)
+        #
+        # The sources objects are constructed from Gemfile as well as from
+        # lockfile. To converge the sources, it is necessary that they match.
+        #
+        # The same applies for `eql?` and `hash`
+        def ==(other)
+          other.is_a?(self.class) && uri == other.uri
+        end
+
+        # When overriding `eql?` please preserve the behaviour as mentioned in
+        # docstring for `==` method.
+        alias_method :eql?, :==
+
+        # When overriding `hash` please preserve the behaviour as mentioned in
+        # docstring for `==` method, i.e. two methods equal by above comparison
+        # should have same hash.
+        def hash
+          [self.class, uri].hash
+        end
+
+        # A helper method, not necessary if not used internally.
+        def installed?
+          File.directory?(install_path)
+        end
+
+        # The full path where the plugin should cache the gem so that it can be
+        # installed latter.
+        #
+        # Note: Do not override if you don't know what you are doing.
+        def app_cache_path(custom_path = nil)
+          @app_cache_path ||= Bundler.app_cache(custom_path).join(app_cache_dirname)
+        end
+
+        # Used by definition.
+        #
+        # Note: Do not override if you don't know what you are doing.
+        def unmet_deps
+          specs.unmet_dependency_names
+        end
+
+        # Used by definition.
+        #
+        # Note: Do not override if you don't know what you are doing.
+        def spec_names
+          specs.spec_names
+        end
+
+        # Used by definition.
+        #
+        # Note: Do not override if you don't know what you are doing.
+        def add_dependency_names(names)
+          @dependencies |= Array(names)
+        end
+
+        # NOTE: Do not override if you don't know what you are doing.
+        def can_lock?(spec)
+          spec.source == self
+        end
+
+        # Generates the content to be entered into the lockfile.
+        # Saves type and remote and also calls to `options_to_lock`.
+        #
+        # Plugin should use `options_to_lock` to save information in lockfile
+        # and not override this.
+        #
+        # Note: Do not override if you don't know what you are doing.
+        def to_lock
+          out = String.new("#{LockfileParser::PLUGIN}\n")
+          out << "  remote: #{@uri}\n"
+          out << "  type: #{@type}\n"
+          options_to_lock.each do |opt, value|
+            out << "  #{opt}: #{value}\n"
+          end
+          out << "  specs:\n"
+        end
+
+        def to_s
+          "plugin source for #{@type} with uri #{@uri}"
+        end
+        alias_method :identifier, :to_s
+
+        # NOTE: Do not override if you don't know what you are doing.
+        def include?(other)
+          other == self
+        end
+
+        def uri_hash
+          SharedHelpers.digest(:SHA1).hexdigest(uri)
+        end
+
+        # NOTE: Do not override if you don't know what you are doing.
+        def gem_install_dir
+          Bundler.install_path
+        end
+
+        # It is used to obtain the full_gem_path.
+        #
+        # spec's loaded_from path is expanded against this to get full_gem_path
+        #
+        # Note: Do not override if you don't know what you are doing.
+        def root
+          Bundler.root
+        end
+
+        # @private
+        # This API on source might not be stable, and for now we expect plugins
+        # to download all specs in `#specs`, so we implement the method for
+        # compatibility purposes and leave it undocumented (and don't support)
+        # overriding it)
+        def double_check_for(*); end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/plugin/dsl.rb b/lib/bundler/plugin/dsl.rb
new file mode 100644
index 0000000000..da751d1774
--- /dev/null
+++ b/lib/bundler/plugin/dsl.rb
@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+module Bundler
+  module Plugin
+    # Dsl to parse the Gemfile looking for plugins to install
+    class DSL < Bundler::Dsl
+      class PluginGemfileError < PluginError; end
+      alias_method :_gem, :gem # To use for plugin installation as gem
+
+      # So that we don't have to override all there methods to dummy ones
+      # explicitly.
+      # They will be handled by method_missing
+      [:gemspec, :gem, :install_if, :platforms, :env].each {|m| undef_method m }
+
+      # This lists the plugins that was added automatically and not specified by
+      # the user.
+      #
+      # When we encounter :type attribute with a source block, we add a plugin
+      # by name bundler-source-<type> to list of plugins to be installed.
+      #
+      # These plugins are optional and are not installed when there is conflict
+      # with any other plugin.
+      attr_reader :inferred_plugins
+
+      def initialize
+        super
+        @sources = Plugin::SourceList.new
+        @inferred_plugins = [] # The source plugins inferred from :type
+      end
+
+      def plugin(name, *args)
+        _gem(name, *args)
+      end
+
+      def method_missing(name, *args)
+        raise PluginGemfileError, "Undefined local variable or method `#{name}' for Gemfile" unless Bundler::Dsl.method_defined? name
+      end
+
+      def source(source, *args, &blk)
+        options = args.last.is_a?(Hash) ? args.pop.dup : {}
+        options = normalize_hash(options)
+        return super unless options.key?("type")
+
+        plugin_name = "bundler-source-#{options["type"]}"
+
+        return if @dependencies.any? {|d| d.name == plugin_name }
+
+        plugin(plugin_name)
+        @inferred_plugins << plugin_name
+      end
+    end
+  end
+end
diff --git a/lib/bundler/plugin/events.rb b/lib/bundler/plugin/events.rb
new file mode 100644
index 0000000000..3fbf60307e
--- /dev/null
+++ b/lib/bundler/plugin/events.rb
@@ -0,0 +1,127 @@
+# frozen_string_literal: true
+
+module Bundler
+  module Plugin
+    module Events
+      def self.define(const, event)
+        const = const.to_sym.freeze
+        if const_defined?(const) && const_get(const) != event
+          raise ArgumentError, "Attempting to reassign #{const} to a different value"
+        end
+        const_set(const, event) unless const_defined?(const)
+        @events ||= {}
+        @events[event] = const
+      end
+      private_class_method :define
+
+      def self.reset
+        @events.each_value do |const|
+          remove_const(const)
+        end
+        @events = nil
+      end
+      private_class_method :reset
+
+      # Check if an event has been defined
+      # @param event [String] An event to check
+      # @return [Boolean] A boolean indicating if the event has been defined
+      def self.defined_event?(event)
+        @events ||= {}
+        @events.key?(event)
+      end
+
+      # @!parse
+      #   A hook called before the Gemfile is evaluated
+      #   Includes the Gemfile path and the Lockfile path
+      #   GEM_BEFORE_EVAL = "before-eval"
+      define :GEM_BEFORE_EVAL, "before-eval"
+
+      # @!parse
+      #   A hook called after the Gemfile is evaluated
+      #   Includes a Bundler::Definition
+      #   GEM_AFTER_EVAL = "after-eval"
+      define :GEM_AFTER_EVAL, "after-eval"
+
+      # @!parse
+      #   A hook called before any gems install
+      #   Includes an Array of Bundler::Dependency objects
+      #   GEM_BEFORE_INSTALL_ALL = "before-install-all"
+      define :GEM_BEFORE_INSTALL_ALL, "before-install-all"
+
+      # @!parse
+      #   A hook called before each individual gem is downloaded from a remote source.
+      #   Includes a spec-like object responding to the Gem::Specification API
+      #   (for example, a Bundler spec proxy such as Bundler::EndpointSpecification
+      #   or Bundler::RemoteSpecification). Does not fire when the gem is already
+      #   present at the initial download-cache check.
+      #   GEM_BEFORE_FETCH = "before-fetch"
+      define :GEM_BEFORE_FETCH, "before-fetch"
+
+      # @!parse
+      #   A hook called after each individual gem is downloaded from a remote source.
+      #   Includes a spec-like object responding to the Gem::Specification API
+      #   (for example, a Bundler spec proxy such as Bundler::EndpointSpecification
+      #   or Bundler::RemoteSpecification). Does not fire when the gem is already
+      #   present at the initial download-cache check.
+      #   GEM_AFTER_FETCH = "after-fetch"
+      define :GEM_AFTER_FETCH, "after-fetch"
+
+      # @!parse
+      #   A hook called before a git source is fetched or checked out.
+      #   Includes a Bundler::Source::Git reference.
+      #   GIT_BEFORE_FETCH = "before-git-fetch"
+      define :GIT_BEFORE_FETCH, "before-git-fetch"
+
+      # @!parse
+      #   A hook called after a git source is fetched or checked out.
+      #   Includes a Bundler::Source::Git reference.
+      #   GIT_AFTER_FETCH = "after-git-fetch"
+      define :GIT_AFTER_FETCH, "after-git-fetch"
+
+      # @!parse
+      #   A hook called before each individual gem is installed
+      #   Includes a Bundler::ParallelInstaller::SpecInstallation.
+      #   No state, error, post_install_message will be present as nothing has installed yet
+      #   GEM_BEFORE_INSTALL = "before-install"
+      define :GEM_BEFORE_INSTALL, "before-install"
+
+      # @!parse
+      #   A hook called after each individual gem is installed
+      #   Includes a Bundler::ParallelInstaller::SpecInstallation.
+      #     - If state is failed, an error will be present.
+      #     - If state is success, a post_install_message may be present.
+      #   GEM_AFTER_INSTALL = "after-install"
+      define :GEM_AFTER_INSTALL,  "after-install"
+
+      # @!parse
+      #   A hook called after any gems install
+      #   Includes an Array of Bundler::Dependency objects
+      #   GEM_AFTER_INSTALL_ALL = "after-install-all"
+      define :GEM_AFTER_INSTALL_ALL,  "after-install-all"
+
+      # @!parse
+      #   A hook called before any gems require
+      #   Includes an Array of Bundler::Dependency objects.
+      #   GEM_BEFORE_REQUIRE_ALL = "before-require-all"
+      define :GEM_BEFORE_REQUIRE_ALL, "before-require-all"
+
+      # @!parse
+      #   A hook called before each individual gem is required
+      #   Includes a Bundler::Dependency.
+      #   GEM_BEFORE_REQUIRE = "before-require"
+      define :GEM_BEFORE_REQUIRE, "before-require"
+
+      # @!parse
+      #   A hook called after each individual gem is required
+      #   Includes a Bundler::Dependency.
+      #   GEM_AFTER_REQUIRE = "after-require"
+      define :GEM_AFTER_REQUIRE,  "after-require"
+
+      # @!parse
+      #   A hook called after all gems required
+      #   Includes an Array of Bundler::Dependency objects.
+      #   GEM_AFTER_REQUIRE_ALL = "after-require-all"
+      define :GEM_AFTER_REQUIRE_ALL, "after-require-all"
+    end
+  end
+end
diff --git a/lib/bundler/plugin/index.rb b/lib/bundler/plugin/index.rb
new file mode 100644
index 0000000000..1dfb061304
--- /dev/null
+++ b/lib/bundler/plugin/index.rb
@@ -0,0 +1,241 @@
+# frozen_string_literal: true
+
+module Bundler
+  # Manages which plugins are installed and their sources. This also is supposed to map
+  # which plugin does what (currently the features are not implemented so this class is
+  # now a stub class).
+  module Plugin
+    class Index
+      class CommandConflict < PluginError
+        def initialize(plugin, commands)
+          msg = "Command(s) `#{commands.join("`, `")}` declared by #{plugin} are already registered."
+          super msg
+        end
+      end
+
+      class SourceConflict < PluginError
+        def initialize(plugin, sources)
+          msg = "Source(s) `#{sources.join("`, `")}` declared by #{plugin} are already registered."
+          super msg
+        end
+      end
+
+      attr_reader :commands
+
+      def initialize
+        @plugin_paths = {}
+        @commands = {}
+        @sources = {}
+        @hooks = {}
+        @load_paths = {}
+
+        begin
+          load_index(global_index_file, true)
+        rescue PermissionError
+          # no need to fail when on a read-only FS, for example
+          nil
+        rescue ArgumentError => e
+          # ruby 3.4 checks writability in Dir.tmpdir
+          raise unless e.message&.include?("could not find a temporary directory")
+          nil
+        end
+        load_index(local_index_file) if SharedHelpers.in_bundle?
+      end
+
+      # This function is to be called when a new plugin is installed. This
+      # function shall add the functions of the plugin to existing maps and also
+      # the name to source location.
+      #
+      # @param [String] name of the plugin to be registered
+      # @param [String] path where the plugin is installed
+      # @param [Array<String>] load_paths for the plugin
+      # @param [Array<String>] commands that are handled by the plugin
+      # @param [Array<String>] sources that are handled by the plugin
+      def register_plugin(name, path, load_paths, commands, sources, hooks)
+        old_commands = @commands.dup
+
+        common = commands & @commands.keys
+        raise CommandConflict.new(name, common) unless common.empty?
+        commands.each {|c| @commands[c] = name }
+
+        common = sources & @sources.keys
+        raise SourceConflict.new(name, common) unless common.empty?
+        sources.each {|k| @sources[k] = name }
+
+        hooks.each do |event|
+          event_hooks = (@hooks[event] ||= []) << name
+          event_hooks.uniq!
+        end
+
+        @plugin_paths[name] = path
+        @load_paths[name] = load_paths
+        save_index
+      rescue StandardError
+        @commands = old_commands
+        raise
+      end
+
+      def unregister_plugin(name)
+        @commands.delete_if {|_, v| v == name }
+        @sources.delete_if {|_, v| v == name }
+        @hooks.each do |hook, names|
+          names.delete(name)
+          @hooks.delete(hook) if names.empty?
+        end
+        @plugin_paths.delete(name)
+        @load_paths.delete(name)
+        save_index
+      end
+
+      # Path of default index file
+      def index_file
+        Plugin.root.join("index")
+      end
+
+      # Path where the global index file is stored
+      def global_index_file
+        Plugin.global_root.join("index")
+      end
+
+      # Path where the local index file is stored
+      def local_index_file
+        Plugin.local_root.join("index")
+      end
+
+      def plugin_path(name)
+        Pathname.new @plugin_paths[name]
+      end
+
+      def load_paths(name)
+        @load_paths[name]
+      end
+
+      # Fetch the name of plugin handling the command
+      def command_plugin(command)
+        @commands[command]
+      end
+
+      def installed?(name)
+        @plugin_paths[name]
+      end
+
+      def up_to_date?(spec)
+        path = installed?(spec.name)
+
+        path == spec.full_gem_path
+      end
+
+      def installed_plugins
+        @plugin_paths.keys
+      end
+
+      def plugin_commands(plugin)
+        @commands.find_all {|_, n| n == plugin }.map(&:first)
+      end
+
+      def source?(source)
+        @sources.key? source
+      end
+
+      def source_plugin(name)
+        @sources[name]
+      end
+
+      # Returns the list of plugin names handling the passed event
+      def hook_plugins(event)
+        @hooks[event] || []
+      end
+
+      # This plugin is installed inside the .bundle/plugin directory,
+      # and thus is managed solely by Bundler
+      def installed_in_plugin_root?(name)
+        return false unless (path = installed?(name))
+
+        path.start_with?("#{Plugin.root}/")
+      end
+
+      private
+
+      # Reads the index file from the directory and initializes the instance
+      # variables.
+      #
+      # It skips the sources if the second param is true
+      # @param [Pathname] index file path
+      # @param [Boolean] is the index file global index
+      def load_index(index_file, global = false)
+        base = base_for_index(global)
+
+        SharedHelpers.filesystem_access(index_file, :read) do |index_f|
+          valid_file = index_f&.exist? && !index_f.size.zero?
+          break unless valid_file
+
+          data = index_f.read
+
+          require_relative "../yaml_serializer"
+          index = YAMLSerializer.load(data)
+
+          @commands.merge!(index["commands"])
+          @hooks.merge!(index["hooks"])
+          @load_paths.merge!(transform_index_paths(index["load_paths"]) {|p| absolutize_path(p, base) })
+          @plugin_paths.merge!(transform_index_paths(index["plugin_paths"]) {|p| absolutize_path(p, base) })
+          @sources.merge!(index["sources"]) unless global
+        end
+      end
+
+      # Should be called when any of the instance variables change. Stores the
+      # instance variables in YAML format. (The instance variables are supposed
+      # to be only String key value pairs)
+      def save_index
+        base = base_for_index(false)
+
+        index = {
+          "commands" => @commands,
+          "hooks" => @hooks,
+          "load_paths" => transform_index_paths(@load_paths) {|p| relativize_path(p, base) },
+          "plugin_paths" => transform_index_paths(@plugin_paths) {|p| relativize_path(p, base) },
+          "sources" => @sources,
+        }
+
+        require_relative "../yaml_serializer"
+        SharedHelpers.filesystem_access(index_file) do |index_f|
+          FileUtils.mkdir_p(index_f.dirname)
+          File.open(index_f, "w") {|f| f.puts YAMLSerializer.dump(index) }
+        end
+      end
+
+      def base_for_index(global)
+        global ? Plugin.global_root : Plugin.root
+      end
+
+      def transform_index_paths(paths)
+        return {} unless paths
+
+        paths.transform_values do |value|
+          if value.is_a?(Array)
+            value.map {|path| yield path }
+          else
+            yield value
+          end
+        end
+      end
+
+      def relativize_path(path, base)
+        pathname = Pathname.new(path)
+        return path unless pathname.absolute?
+
+        base_path = Pathname.new(base)
+        if pathname == base_path || pathname.to_s.start_with?(base_path.to_s + File::SEPARATOR)
+          pathname.relative_path_from(base_path).to_s
+        else
+          path
+        end
+      end
+
+      def absolutize_path(path, base)
+        pathname = Pathname.new(path)
+        pathname = Pathname.new(base).join(pathname) unless pathname.absolute?
+        pathname.to_s
+      end
+    end
+  end
+end
diff --git a/lib/bundler/plugin/installer.rb b/lib/bundler/plugin/installer.rb
new file mode 100644
index 0000000000..9be8b36843
--- /dev/null
+++ b/lib/bundler/plugin/installer.rb
@@ -0,0 +1,123 @@
+# frozen_string_literal: true
+
+module Bundler
+  # Handles the installation of plugin in appropriate directories.
+  #
+  # This class is supposed to be wrapper over the existing gem installation infra
+  # but currently it itself handles everything as the Source's subclasses (e.g. Source::RubyGems)
+  # are heavily dependent on the Gemfile.
+  module Plugin
+    class Installer
+      autoload :Rubygems, File.expand_path("installer/rubygems", __dir__)
+      autoload :Git,      File.expand_path("installer/git", __dir__)
+      autoload :Path, File.expand_path("installer/path", __dir__)
+
+      def install(names, options)
+        check_sources_consistency!(options)
+
+        version = options[:version] || [">= 0"]
+
+        if options[:git]
+          install_git(names, version, options)
+        elsif options[:path]
+          install_path(names, version, options[:path])
+        else
+          sources = options[:source] || Gem.sources
+          install_rubygems(names, version, sources)
+        end
+      end
+
+      # Installs the plugin from Definition object created by limited parsing of
+      # Gemfile searching for plugins to be installed
+      #
+      # @param [Definition] definition object
+      # @return [Hash] map of names to their specs they are installed with
+      def install_definition(definition)
+        def definition.lock(*); end
+        definition.remotely!
+        specs = definition.specs
+
+        install_from_specs specs
+      end
+
+      private
+
+      def check_sources_consistency!(options)
+        if (options.keys & [:source, :git, :path]).length > 1
+          raise InvalidOption, "Only one of --source, --git, or --path may be specified"
+        end
+
+        if (options.key?(:branch) || options.key?(:ref)) && !options.key?(:git)
+          raise InvalidOption, "--#{options.key?(:branch) ? "branch" : "ref"} can only be used with git sources"
+        end
+
+        if options.key?(:branch) && options.key?(:ref)
+          raise InvalidOption, "--branch and --ref can't be both specified"
+        end
+      end
+
+      def install_git(names, version, options)
+        source_list = SourceList.new
+        source = source_list.add_git_source({ "uri" => options[:git],
+                                              "branch" => options[:branch],
+                                              "ref" => options[:ref] })
+
+        install_all_sources(names, version, source_list, source)
+      end
+
+      def install_path(names, version, path)
+        source_list = SourceList.new
+        source = source_list.add_path_source({ "path" => path, "root_path" => SharedHelpers.pwd })
+
+        install_all_sources(names, version, source_list, source)
+      end
+
+      # Installs the plugin from rubygems source and returns the path where the
+      # plugin was installed
+      #
+      # @param [String] name of the plugin gem to search in the source
+      # @param [Array] version of the gem to install
+      # @param [String, Array<String>] source(s) to resolve the gem
+      #
+      # @return [Hash] map of names to the specs of plugins installed
+      def install_rubygems(names, version, sources)
+        source_list = SourceList.new
+
+        Array(sources).each {|remote| source_list.add_global_rubygems_remote(remote) }
+
+        install_all_sources(names, version, source_list)
+      end
+
+      def install_all_sources(names, version, source_list, source = nil)
+        deps = names.map {|name| Dependency.new(name, version, { "source" => source }) }
+
+        Bundler.configure_gem_home_and_path(Plugin.root)
+
+        Bundler.settings.temporary(deployment: false, frozen: false) do
+          definition = Definition.new(nil, deps, source_list, true)
+
+          install_definition(definition)
+        end
+      end
+
+      # Installs the plugins and deps from the provided specs and returns map of
+      # gems to their paths
+      #
+      # @param specs to install
+      #
+      # @return [Hash] map of names to the specs
+      def install_from_specs(specs)
+        paths = {}
+
+        specs.each do |spec|
+          spec.source.download(spec)
+          spec.source.install(spec)
+
+          paths[spec.name] = spec
+        end
+
+        paths
+      end
+    end
+  end
+end
diff --git a/lib/bundler/plugin/installer/git.rb b/lib/bundler/plugin/installer/git.rb
new file mode 100644
index 0000000000..deec5e99b3
--- /dev/null
+++ b/lib/bundler/plugin/installer/git.rb
@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+module Bundler
+  module Plugin
+    class Installer
+      class Git < Bundler::Source::Git
+        def cache_path
+          @cache_path ||= begin
+            git_scope = "#{base_name}-#{uri_hash}"
+
+            Plugin.cache.join("bundler", "git", git_scope)
+          end
+        end
+
+        def install_path
+          @install_path ||= begin
+            git_scope = "#{base_name}-#{shortref_for_path(revision)}"
+
+            Plugin.root.join("bundler", "gems", git_scope)
+          end
+        end
+
+        def root
+          Plugin.root
+        end
+
+        def generate_bin(spec, disable_extensions = false)
+          # Need to find a way without code duplication
+          # For now, we can ignore this
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/plugin/installer/path.rb b/lib/bundler/plugin/installer/path.rb
new file mode 100644
index 0000000000..58c4924eb0
--- /dev/null
+++ b/lib/bundler/plugin/installer/path.rb
@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+module Bundler
+  module Plugin
+    class Installer
+      class Path < Bundler::Source::Path
+        def root
+          SharedHelpers.in_bundle? ? Bundler.root : Plugin.root
+        end
+
+        def eql?(other)
+          return unless other.class == self.class
+          expanded_original_path == other.expanded_original_path &&
+            version == other.version
+        end
+
+        alias_method :==, :eql?
+
+        def generate_bin(spec, disable_extensions = false)
+          # Need to find a way without code duplication
+          # For now, we can ignore this
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/plugin/installer/rubygems.rb b/lib/bundler/plugin/installer/rubygems.rb
new file mode 100644
index 0000000000..cb5db9c30e
--- /dev/null
+++ b/lib/bundler/plugin/installer/rubygems.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+module Bundler
+  module Plugin
+    class Installer
+      class Rubygems < Bundler::Source::Rubygems
+        private
+
+        def rubygems_dir
+          Plugin.root
+        end
+
+        def cache_path
+          Plugin.cache
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/plugin/source_list.rb b/lib/bundler/plugin/source_list.rb
new file mode 100644
index 0000000000..d929ade29e
--- /dev/null
+++ b/lib/bundler/plugin/source_list.rb
@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+module Bundler
+  # SourceList object to be used while parsing the Gemfile, setting the
+  # approptiate options to be used with Source classes for plugin installation
+  module Plugin
+    class SourceList < Bundler::SourceList
+      def add_git_source(options = {})
+        add_source_to_list Plugin::Installer::Git.new(options), git_sources
+      end
+
+      def add_path_source(options = {})
+        add_source_to_list Plugin::Installer::Path.new(options), path_sources
+      end
+
+      def add_rubygems_source(options = {})
+        add_source_to_list Plugin::Installer::Rubygems.new(options), @rubygems_sources
+      end
+
+      def all_sources
+        path_sources + git_sources + rubygems_sources + [metadata_source]
+      end
+
+      private
+
+      def source_class
+        Plugin::Installer::Rubygems
+      end
+    end
+  end
+end
diff --git a/lib/bundler/process_lock.rb b/lib/bundler/process_lock.rb
new file mode 100644
index 0000000000..784b17e363
--- /dev/null
+++ b/lib/bundler/process_lock.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+module Bundler
+  class ProcessLock
+    def self.lock(bundle_path = Bundler.bundle_path, &block)
+      lock_file_path = File.join(bundle_path, "bundler.lock")
+      base_lock_file_path = lock_file_path.delete_suffix(".lock")
+
+      require "fileutils" if Bundler.rubygems.provides?("< 3.6.0")
+
+      begin
+        SharedHelpers.filesystem_access(lock_file_path, :write) do
+          Gem.open_file_with_lock(base_lock_file_path, &block)
+        end
+      rescue PermissionError
+        block.call
+      end
+    end
+  end
+end
diff --git a/lib/bundler/remote_specification.rb b/lib/bundler/remote_specification.rb
new file mode 100644
index 0000000000..dcaaf6af2e
--- /dev/null
+++ b/lib/bundler/remote_specification.rb
@@ -0,0 +1,126 @@
+# frozen_string_literal: true
+
+module Bundler
+  # Represents a lazily loaded gem specification, where the full specification
+  # is on the source server in rubygems' "quick" index. The proxy object is to
+  # be seeded with what we're given from the source's abbreviated index - the
+  # full specification will only be fetched when necessary.
+  class RemoteSpecification
+    include MatchRemoteMetadata
+    include MatchPlatform
+    include Comparable
+
+    attr_reader :name, :version, :platform
+    attr_writer :dependencies
+    attr_accessor :source, :remote, :locked_platform, :created_at
+
+    def initialize(name, version, platform, spec_fetcher)
+      @name         = name
+      @version      = Gem::Version.create version
+      @original_platform = platform || Gem::Platform::RUBY
+      @platform     = Gem::Platform.new(platform)
+      @spec_fetcher = spec_fetcher
+      @dependencies = nil
+      @locked_platform = nil
+    end
+
+    def insecurely_materialized?
+      @locked_platform.to_s != @platform.to_s
+    end
+
+    # Needed before installs, since the arch matters then and quick
+    # specs don't bother to include the arch in the platform string
+    def fetch_platform
+      @platform = _remote_specification.platform
+    end
+
+    def full_name
+      @full_name ||= if @platform == Gem::Platform::RUBY
+        "#{@name}-#{@version}"
+      else
+        "#{@name}-#{@version}-#{@platform}"
+      end
+    end
+
+    # Compare this specification against another object. Using sort_obj
+    # is compatible with Gem::Specification and other Bundler or RubyGems
+    # objects. Otherwise, use the default Object comparison.
+    def <=>(other)
+      if other.respond_to?(:sort_obj)
+        sort_obj <=> other.sort_obj
+      else
+        super
+      end
+    end
+
+    # Because Rubyforge cannot be trusted to provide valid specifications
+    # once the remote gem is downloaded, the backend specification will
+    # be swapped out.
+    def __swap__(spec)
+      raise APIResponseInvalidDependenciesError unless spec.dependencies.all? {|d| d.is_a?(Gem::Dependency) }
+
+      SharedHelpers.ensure_same_dependencies(self, dependencies, spec.dependencies)
+      @_remote_specification = spec
+    end
+
+    # Create a delegate used for sorting. This strategy is copied from
+    # RubyGems 2.23 and ensures that Bundler's specifications can be
+    # compared and sorted with RubyGems' own specifications.
+    #
+    # @see #<=>
+    # @see Gem::Specification#sort_obj
+    #
+    # @return [Array] an object you can use to compare and sort this
+    #   specification against other specifications
+    def sort_obj
+      [@name, @version, @platform == Gem::Platform::RUBY ? -1 : 1]
+    end
+
+    def to_s
+      "#<#{self.class} name=#{name} version=#{version} platform=#{platform}>"
+    end
+
+    def dependencies
+      @dependencies ||= begin
+        deps = method_missing(:dependencies)
+
+        # allow us to handle when the specs dependencies are an array of array of string
+        # in order to delay the crash to `#__swap__` where it results in a friendlier error
+        # see https://github.com/rubygems/bundler/issues/5797
+        deps = deps.map {|d| d.is_a?(Gem::Dependency) ? d : Gem::Dependency.new(*d) }
+
+        deps
+      end
+    end
+
+    def runtime_dependencies
+      dependencies.select(&:runtime?)
+    end
+
+    def git_version
+      return unless loaded_from && source.is_a?(Bundler::Source::Git)
+      " #{source.revision[0..6]}"
+    end
+
+    private
+
+    def to_ary
+      nil
+    end
+
+    def _remote_specification
+      @_remote_specification ||= @spec_fetcher.fetch_spec([@name, @version, @original_platform])
+      @_remote_specification || raise(GemspecError, "Gemspec data for #{full_name} was" \
+        " missing from the server!")
+    end
+
+    def method_missing(method, *args, &blk)
+      _remote_specification.send(method, *args, &blk)
+    end
+
+    def respond_to?(method, include_all = false)
+      super || _remote_specification.respond_to?(method, include_all)
+    end
+    public :respond_to?
+  end
+end
diff --git a/lib/bundler/resolver.rb b/lib/bundler/resolver.rb
new file mode 100644
index 0000000000..753e9987d5
--- /dev/null
+++ b/lib/bundler/resolver.rb
@@ -0,0 +1,645 @@
+# frozen_string_literal: true
+
+module Bundler
+  #
+  # This class implements the interface needed by PubGrub for resolution. It is
+  # equivalent to the `PubGrub::BasicPackageSource` class provided by PubGrub by
+  # default and used by the most simple PubGrub consumers.
+  #
+  class Resolver
+    require_relative "vendored_pub_grub"
+    require_relative "resolver/base"
+    require_relative "resolver/candidate"
+    require_relative "resolver/incompatibility"
+    require_relative "resolver/root"
+    require_relative "resolver/strategy"
+
+    def initialize(base, gem_version_promoter, most_specific_locked_platform = nil)
+      @source_requirements = base.source_requirements
+      @base = base
+      @gem_version_promoter = gem_version_promoter
+      @most_specific_locked_platform = most_specific_locked_platform
+    end
+
+    def start
+      @requirements = @base.requirements
+      @packages = @base.packages
+
+      root, logger = setup_solver
+
+      Bundler.ui.info "Resolving dependencies...", true
+
+      solve_versions(root: root, logger: logger)
+    end
+
+    def setup_solver
+      root = Resolver::Root.new(name_for_explicit_dependency_source)
+      root_version = Resolver::Candidate.new(0)
+
+      @all_specs = Hash.new do |specs, name|
+        source = source_for(name)
+        matches = source.specs.search(name)
+
+        # Don't bother to check for circular deps when no dependency API are
+        # available, since it's too slow to be usable. That edge case won't work
+        # but resolution other than that should work fine and reasonably fast.
+        if source.respond_to?(:dependency_api_available?) && source.dependency_api_available?
+          matches = filter_invalid_self_dependencies(matches, name)
+        end
+
+        specs[name] = matches.sort_by {|s| [s.version, s.platform.to_s] }
+      end
+
+      @all_versions = Hash.new do |candidates, package|
+        candidates[package] = all_versions_for(package)
+      end
+
+      @sorted_versions = Hash.new do |candidates, package|
+        candidates[package] = filtered_versions_for(package).sort
+      end
+
+      @sorted_versions[root] = [root_version]
+
+      root_dependencies = prepare_dependencies(@requirements, @packages)
+
+      @cached_dependencies = Hash.new do |dependencies, package|
+        dependencies[package] = Hash.new do |versions, version|
+          deps = version.dependencies.reject {|d| d.name == package.name }
+          deps = apply_metadata_overrides(deps, package.name)
+          versions[version] = to_dependency_hash(deps, @packages)
+        end
+      end
+
+      @cached_dependencies[root] = { root_version => root_dependencies }
+
+      logger = Bundler::UI::Shell.new
+      logger.level = debug? ? "debug" : "warn"
+
+      [root, logger]
+    end
+
+    def solve_versions(root:, logger:)
+      solver = PubGrub::VersionSolver.new(source: self, root: root, strategy: Strategy.new(self), logger: logger)
+      result = solver.solve
+      resolved_specs = result.flat_map {|package, version| version.to_specs(package, @most_specific_locked_platform) }
+      Override.attach(resolved_specs, @base.overrides)
+      SpecSet.new(resolved_specs).specs_with_additional_variants_from(@base.locked_specs)
+    rescue PubGrub::SolveFailure => e
+      incompatibility = e.incompatibility
+
+      names_to_unlock, names_to_allow_prereleases_for, names_to_allow_remote_specs_for, extended_explanation = find_names_to_relax(incompatibility)
+
+      names_to_relax = names_to_unlock + names_to_allow_prereleases_for + names_to_allow_remote_specs_for
+
+      if names_to_relax.any?
+        if names_to_unlock.any?
+          Bundler.ui.debug "Found conflicts with locked dependencies. Will retry with #{names_to_unlock.join(", ")} unlocked...", true
+
+          @base.unlock_names(names_to_unlock)
+        end
+
+        if names_to_allow_prereleases_for.any?
+          Bundler.ui.debug "Found conflicts with dependencies with prereleases. Will retry considering prereleases for #{names_to_allow_prereleases_for.join(", ")}...", true
+
+          @base.include_prereleases(names_to_allow_prereleases_for)
+        end
+
+        if names_to_allow_remote_specs_for.any?
+          Bundler.ui.debug "Found conflicts with local versions of #{names_to_allow_remote_specs_for.join(", ")}. Will retry considering remote versions...", true
+
+          @base.include_remote_specs(names_to_allow_remote_specs_for)
+        end
+
+        root, logger = setup_solver
+
+        Bundler.ui.debug "Retrying resolution...", true
+        retry
+      end
+
+      explanation = e.message
+
+      if extended_explanation
+        explanation << "\n\n"
+        explanation << extended_explanation
+      end
+
+      override_summary = override_diagnostic_summary
+      explanation << override_summary if override_summary
+
+      raise SolveFailure.new(explanation)
+    end
+
+    def override_diagnostic_summary
+      return nil if @base.overrides.empty?
+
+      lines = ["Bundler applied the following overrides while resolving:"]
+      @base.overrides.each do |override|
+        target = override.target == :all ? ":all" : override.target.inspect
+        location = override.source_location_label
+        lines << "  override #{target}, #{override.field}: #{override.operation.inspect}" \
+          "#{location ? " (declared at #{location})" : ""}"
+      end
+      "\n\n#{lines.join("\n")}"
+    end
+
+    def find_names_to_relax(incompatibility)
+      names_to_unlock = []
+      names_to_allow_prereleases_for = []
+      names_to_allow_remote_specs_for = []
+      extended_explanation = nil
+
+      while incompatibility.conflict?
+        cause = incompatibility.cause
+        incompatibility = cause.incompatibility
+
+        incompatibility.terms.each do |term|
+          package = term.package
+          name = package.name
+
+          if base_requirements[name]
+            names_to_unlock << name
+          elsif package.ignores_prereleases? && @all_specs[name].any? {|s| s.version.prerelease? }
+            names_to_allow_prereleases_for << name
+          elsif package.prefer_local? && @all_specs[name].any? {|s| !s.is_a?(StubSpecification) }
+            names_to_allow_remote_specs_for << name
+          end
+
+          no_versions_incompat = [cause.incompatibility, cause.satisfier].find {|incompat| incompat.cause.is_a?(PubGrub::Incompatibility::NoVersions) }
+          next unless no_versions_incompat
+
+          extended_explanation = no_versions_incompat.extended_explanation
+        end
+      end
+
+      [names_to_unlock.uniq, names_to_allow_prereleases_for.uniq, names_to_allow_remote_specs_for.uniq, extended_explanation]
+    end
+
+    def parse_dependency(package, dependency)
+      range = if repository_for(package).is_a?(Source::Gemspec)
+        PubGrub::VersionRange.any
+      else
+        requirement_to_range(dependency)
+      end
+
+      PubGrub::VersionConstraint.new(package, range: range)
+    end
+
+    def versions_for(package, range = VersionRange.any)
+      range.select_versions(@sorted_versions[package])
+    end
+
+    def no_versions_incompatibility_for(package, unsatisfied_term)
+      cause = PubGrub::Incompatibility::NoVersions.new(unsatisfied_term)
+      name = package.name
+      constraint = unsatisfied_term.constraint
+      constraint_string = constraint.constraint_string
+      requirements = constraint_string.split(" OR ").map {|req| Gem::Requirement.new(req.split(",")) }
+
+      if name == "bundler" && bundler_pinned_to_current_version?
+        custom_explanation = "the current Bundler version (#{Bundler::VERSION}) does not satisfy #{constraint}"
+        extended_explanation = bundler_not_found_message(requirements)
+      else
+        specs_matching_other_platforms = filter_matching_specs(@all_specs[name], requirements)
+
+        platforms_explanation = specs_matching_other_platforms.any? ? " for any resolution platforms (#{package.platforms.join(", ")})" : ""
+        custom_explanation = "#{constraint} could not be found in #{repository_for(package)}#{platforms_explanation}"
+        if hint = cooldown_hint(specs_matching_other_platforms)
+          custom_explanation += " (#{hint})"
+        end
+
+        label = "#{name} (#{constraint_string})"
+        extended_explanation = other_specs_matching_message(specs_matching_other_platforms, label) if specs_matching_other_platforms.any?
+      end
+
+      Incompatibility.new([unsatisfied_term], cause: cause, custom_explanation: custom_explanation, extended_explanation: extended_explanation)
+    end
+
+    def debug?
+      ENV["BUNDLER_DEBUG_RESOLVER"] ||
+        ENV["BUNDLER_DEBUG_RESOLVER_TREE"] ||
+        ENV["DEBUG_RESOLVER"] ||
+        ENV["DEBUG_RESOLVER_TREE"] ||
+        false
+    end
+
+    def incompatibilities_for(package, version)
+      package_deps = @cached_dependencies[package]
+      sorted_versions = @sorted_versions[package]
+      package_deps[version].map do |dep_package, dep_constraint|
+        low = high = sorted_versions.index(version)
+
+        # find version low such that all >= low share the same dep
+        while low > 0 && package_deps[sorted_versions[low - 1]][dep_package] == dep_constraint
+          low -= 1
+        end
+        low =
+          if low == 0
+            nil
+          else
+            sorted_versions[low]
+          end
+
+        # find version high such that all < high share the same dep
+        while high < sorted_versions.length && package_deps[sorted_versions[high]][dep_package] == dep_constraint
+          high += 1
+        end
+        high =
+          if high == sorted_versions.length
+            nil
+          else
+            sorted_versions[high]
+          end
+
+        range = PubGrub::VersionRange.new(min: low, max: high, include_min: !low.nil?)
+
+        self_constraint = PubGrub::VersionConstraint.new(package, range: range)
+
+        dep_term = PubGrub::Term.new(dep_constraint, false)
+        self_term = PubGrub::Term.new(self_constraint, true)
+
+        custom_explanation = if dep_package.meta? && package.root?
+          "current #{dep_package} version is #{dep_constraint.constraint_string}"
+        end
+
+        PubGrub::Incompatibility.new([self_term, dep_term], cause: :dependency, custom_explanation: custom_explanation)
+      end
+    end
+
+    def all_versions_for(package)
+      name = package.name
+      results = (@base[name] + filter_specs(@all_specs[name], package)).uniq {|spec| [spec.version.hash, spec.platform] }
+
+      if name == "bundler" && !bundler_pinned_to_current_version?
+        bundler_spec = Gem.loaded_specs["bundler"]
+        results << bundler_spec if bundler_spec
+      end
+
+      locked_requirement = base_requirements[name]
+      results = filter_matching_specs(results, locked_requirement) if locked_requirement
+
+      results.group_by(&:version).reduce([]) do |groups, (version, specs)|
+        platform_specs = package.platform_specs(specs)
+
+        # If package is a top-level dependency,
+        #   candidate is only valid if there are matching versions for all resolution platforms.
+        #
+        # If package is not a top-level deependency,
+        #   then it's not necessary that it has matching versions for all platforms, since it may have been introduced only as
+        #   a dependency for a platform specific variant, so it will only need to have a valid version for that platform.
+        #
+        if package.top_level?
+          next groups if platform_specs.any?(&:empty?)
+        else
+          next groups if platform_specs.all?(&:empty?)
+        end
+
+        ruby_specs = MatchPlatform.select_best_platform_match(specs, Gem::Platform::RUBY)
+        ruby_group = Resolver::SpecGroup.new(ruby_specs)
+
+        unless ruby_group.empty?
+          platform_specs.each do |s|
+            ruby_group.merge(Resolver::SpecGroup.new(s))
+          end
+
+          groups << Resolver::Candidate.new(version, group: ruby_group, priority: -1)
+          next groups if package.force_ruby_platform?
+        end
+
+        platform_group = Resolver::SpecGroup.new(platform_specs.flatten.uniq)
+        next groups if platform_group == ruby_group
+
+        groups << Resolver::Candidate.new(version, group: platform_group, priority: 1)
+
+        groups
+      end
+    end
+
+    def source_for(name)
+      @source_requirements[name] || @source_requirements[:default]
+    end
+
+    def default_bundler_source
+      @source_requirements[:default_bundler]
+    end
+
+    def bundler_pinned_to_current_version?
+      !default_bundler_source.nil?
+    end
+
+    def name_for_explicit_dependency_source
+      Bundler.default_gemfile.basename.to_s
+    rescue StandardError
+      "Gemfile"
+    end
+
+    def raise_incomplete!(incomplete_specs)
+      raise_not_found!(@base.get_package(incomplete_specs.first.name))
+    end
+
+    def sort_versions_by_preferred(package, versions)
+      @gem_version_promoter.sort_versions(package, versions)
+    end
+
+    private
+
+    def raise_not_found!(package)
+      name = package.name
+      source = source_for(name)
+      specs = @all_specs[name]
+      matching_part = name
+      requirement_label = SharedHelpers.pretty_dependency(package.dependency)
+      cache_message = begin
+                          " or in gems cached in #{Bundler.settings.app_cache_path}" if Bundler.app_cache.exist?
+                        rescue GemfileNotFound
+                          nil
+                        end
+      specs_matching_requirement = filter_matching_specs(specs, package.dependency.requirement)
+
+      not_found_message = if specs_matching_requirement.any?
+        specs = specs_matching_requirement
+        matching_part = requirement_label
+        platforms = package.platforms
+
+        if platforms.size == 1
+          "Could not find gem '#{requirement_label}' with platform '#{platforms.first}'"
+        else
+          "Could not find gems matching '#{requirement_label}' valid for all resolution platforms (#{platforms.join(", ")})"
+        end
+      else
+        "Could not find gem '#{requirement_label}'"
+      end
+
+      message = String.new("#{not_found_message} in #{source}#{cache_message}.\n")
+
+      if specs.any?
+        message << "\n#{other_specs_matching_message(specs, matching_part)}"
+      end
+
+      if hint = cooldown_hint(specs_matching_requirement)
+        message << "\n\n#{hint}."
+      end
+
+      if specs_matching_requirement.any? && (hint = platform_mismatch_hint)
+        message << "\n\n#{hint}"
+      end
+
+      raise GemNotFound, message
+    end
+
+    def platform_mismatch_hint
+      locked_platforms = Bundler.locked_gems&.platforms
+      return unless locked_platforms
+
+      local_platform = Bundler.local_platform
+      return if locked_platforms.include?(local_platform)
+      return if locked_platforms.any? {|p| p == Gem::Platform::RUBY }
+
+      "Your current platform (#{local_platform}) is not included in the lockfile's platforms (#{locked_platforms.join(", ")}). " \
+        "Add the current platform to the lockfile with\n`bundle lock --add-platform #{local_platform}` and try again."
+    rescue GemfileNotFound
+      nil
+    end
+
+    def filtered_versions_for(package)
+      @gem_version_promoter.filter_versions(package, @all_versions[package])
+    end
+
+    def raise_all_versions_filtered_out!(package)
+      level = @gem_version_promoter.level
+      name = package.name
+      locked_version = package.locked_version
+      requirement = package.dependency
+
+      raise GemNotFound,
+        "#{name} is locked to #{locked_version}, while Gemfile is requesting #{requirement}. " \
+        "--strict --#{level} was specified, but there are no #{level} level upgrades from #{locked_version} satisfying #{requirement}, so version solving has failed"
+    end
+
+    def filter_matching_specs(specs, requirements)
+      Array(requirements).flat_map do |requirement|
+        specs.select {| spec| requirement_satisfied_by?(requirement, spec) }
+      end
+    end
+
+    def filter_specs(specs, package)
+      filter_remote_specs(filter_cooldown(filter_prereleases(specs, package)), package)
+    end
+
+    def filter_prereleases(specs, package)
+      return specs unless package.ignores_prereleases? && specs.size > 1
+
+      specs.reject {|s| s.version.prerelease? }
+    end
+
+    def filter_cooldown(specs)
+      return specs if specs.empty?
+      excluded_versions = cooldown_excluded_versions(specs)
+      return specs if excluded_versions.empty?
+      specs.reject {|s| excluded_versions.include?([s.name, s.version]) }
+    end
+
+    def cooldown_excluded_versions(specs)
+      excluded = {}
+      specs.each do |spec|
+        next unless cooldown_excluded?(spec)
+        excluded[[spec.name, spec.version]] = true
+      end
+      excluded
+    end
+
+    def cooldown_hint(specs)
+      excluded_versions = cooldown_excluded_versions(specs)
+      return nil if excluded_versions.empty?
+      "#{excluded_versions.size} version#{"s" if excluded_versions.size > 1} excluded by the cooldown setting; pass `--cooldown 0` to bypass"
+    end
+
+    def cooldown_excluded?(spec)
+      return false unless spec.respond_to?(:created_at) && spec.created_at
+      return false unless spec.respond_to?(:remote) && spec.remote
+      return false if pinned_by_lockfile_floor?(spec)
+      days = spec.remote.effective_cooldown
+      return false if days.nil? || days <= 0
+      (cooldown_now - spec.created_at) < (days * 86_400)
+    end
+
+    # A spec sitting exactly at a `>= locked_version` prevent-downgrade floor is
+    # the version the lockfile currently pins. `bundle update` and `bundle
+    # outdated` install that floor so resolution never moves a gem backwards.
+    # Filtering it out for cooldown would then make resolution impossible
+    # whenever the locked version is itself inside the cooldown window, which is
+    # exactly what happens to a lockfile written before cooldown was enabled.
+    # Keep it eligible; gems being explicitly updated carry an exact `=`
+    # requirement instead and stay subject to the cooldown filter.
+    def pinned_by_lockfile_floor?(spec)
+      return false unless defined?(@base) && @base
+      requirement = base_requirements[spec.name]
+      return false unless requirement && !requirement.exact?
+      requirement.requirements.any? {|op, version| op == ">=" && version == spec.version }
+    end
+
+    def cooldown_now
+      @cooldown_now ||= Time.now
+    end
+
+    def filter_remote_specs(specs, package)
+      if package.prefer_local?
+        local_specs = specs.select {|s| s.is_a?(StubSpecification) }
+
+        if local_specs.empty?
+          package.consider_remote_versions!
+          specs
+        else
+          local_specs
+        end
+      else
+        specs
+      end
+    end
+
+    # Ignore versions that depend on themselves incorrectly
+    def filter_invalid_self_dependencies(specs, name)
+      specs.reject do |s|
+        s.dependencies.any? {|d| d.name == name && !d.requirement.satisfied_by?(s.version) }
+      end
+    end
+
+    def requirement_satisfied_by?(requirement, spec)
+      requirement.satisfied_by?(spec.version) || spec.source.is_a?(Source::Gemspec)
+    end
+
+    def repository_for(package)
+      source_for(package.name)
+    end
+
+    def base_requirements
+      @base.base_requirements
+    end
+
+    def prepare_dependencies(requirements, packages)
+      to_dependency_hash(requirements, packages).filter_map do |dep_package, dep_constraint|
+        name = dep_package.name
+
+        next [dep_package, dep_constraint] if name == "bundler"
+
+        dep_range = dep_constraint.range
+        versions = versions_for(dep_package, dep_range)
+        if versions.empty?
+          if dep_package.ignores_prereleases? || dep_package.prefer_local?
+            @all_versions.delete(dep_package)
+            @sorted_versions.delete(dep_package)
+          end
+          dep_package.consider_prereleases! if dep_package.ignores_prereleases?
+          dep_package.consider_remote_versions! if dep_package.prefer_local?
+          versions = versions_for(dep_package, dep_range)
+        end
+
+        if versions.empty? && select_all_versions(dep_package, dep_range).any?
+          raise_all_versions_filtered_out!(dep_package)
+        end
+
+        next [dep_package, dep_constraint] unless versions.empty?
+
+        next unless dep_package.current_platform?
+
+        raise_not_found!(dep_package)
+      end.to_h
+    end
+
+    def select_all_versions(package, range)
+      range.select_versions(@all_versions[package])
+    end
+
+    def other_specs_matching_message(specs, requirement)
+      message = String.new("The source contains the following gems matching '#{requirement}':\n")
+      message << specs.map {|s| "  * #{s.full_name}" }.join("\n")
+      message
+    end
+
+    def requirement_to_range(requirement)
+      ranges = requirement.requirements.map do |(op, version)|
+        ver = Resolver::Candidate.new(version, priority: -1)
+        platform_ver = Resolver::Candidate.new(version, priority: 1)
+
+        case op
+        when "~>"
+          name = "~> #{ver}"
+          bump = Resolver::Candidate.new(version.bump.to_s + ".A")
+          PubGrub::VersionRange.new(name: name, min: ver, max: bump, include_min: true)
+        when ">"
+          PubGrub::VersionRange.new(min: platform_ver)
+        when ">="
+          PubGrub::VersionRange.new(min: ver, include_min: true)
+        when "<"
+          PubGrub::VersionRange.new(max: ver)
+        when "<="
+          PubGrub::VersionRange.new(max: platform_ver, include_max: true)
+        when "="
+          PubGrub::VersionRange.new(min: ver, max: platform_ver, include_min: true, include_max: true)
+        when "!="
+          PubGrub::VersionRange.new(min: ver, max: platform_ver, include_min: true, include_max: true).invert
+        else
+          raise "bad version specifier: #{op}"
+        end
+      end
+
+      ranges.inject(&:intersect)
+    end
+
+    def to_dependency_hash(dependencies, packages)
+      apply_overrides(dependencies).inject({}) do |deps, dep|
+        package = packages[dep.name]
+
+        current_req = deps[package]
+        new_req = parse_dependency(package, dep.requirement)
+
+        deps[package] = if current_req
+          current_req.intersect(new_req)
+        else
+          new_req
+        end
+
+        deps
+      end
+    end
+
+    def apply_overrides(dependencies)
+      return dependencies if @base.overrides.empty?
+
+      dependencies.map do |dep|
+        override = Override.find_for(@base.overrides, dep.name, :version)
+        next dep unless override
+        Gem::Dependency.new(dep.name, override.apply_to(dep.requirement))
+      end
+    end
+
+    METADATA_DEP_FIELD = {
+      "Ruby\0" => :required_ruby_version,
+      "RubyGems\0" => :required_rubygems_version,
+    }.freeze
+
+    def apply_metadata_overrides(dependencies, name)
+      return dependencies if @base.overrides.empty?
+
+      dependencies.map do |dep|
+        field = METADATA_DEP_FIELD[dep.name]
+        next dep unless field
+        override = Override.find_for(@base.overrides, name, field)
+        next dep unless override
+        Gem::Dependency.new(dep.name, override.apply_to(dep.requirement))
+      end
+    end
+
+    def bundler_not_found_message(conflict_dependencies)
+      candidate_specs = filter_matching_specs(default_bundler_source.specs.search("bundler"), conflict_dependencies)
+
+      if candidate_specs.any?
+        target_version = candidate_specs.last.version
+        new_command = [File.basename($PROGRAM_NAME), "_#{target_version}_", *ARGV].join(" ")
+        "Your bundle requires a different version of Bundler than the one you're running.\n" \
+        "Install the necessary version with `gem install bundler:#{target_version}` and rerun bundler using `#{new_command}`\n"
+      else
+        "Your bundle requires a different version of Bundler than the one you're running, and that version could not be found.\n"
+      end
+    end
+  end
+end
diff --git a/lib/bundler/resolver/base.rb b/lib/bundler/resolver/base.rb
new file mode 100644
index 0000000000..00bdd08303
--- /dev/null
+++ b/lib/bundler/resolver/base.rb
@@ -0,0 +1,119 @@
+# frozen_string_literal: true
+
+require_relative "package"
+
+module Bundler
+  class Resolver
+    class Base
+      attr_reader :packages, :requirements, :source_requirements, :locked_specs, :overrides
+
+      def initialize(source_requirements, dependencies, base, platforms, options)
+        @overrides = options.delete(:overrides) || []
+        @source_requirements = source_requirements
+        @locked_specs = options[:locked_specs]
+
+        @base = base
+
+        @packages = Hash.new do |hash, name|
+          hash[name] = Package.new(name, platforms, **options)
+        end
+
+        @requirements = dependencies.filter_map do |dep|
+          dep_platforms = dep.gem_platforms(platforms)
+
+          # Dependencies scoped to external platforms are ignored
+          next if dep_platforms.empty?
+
+          name = dep.name
+
+          @packages[name] = Package.new(name, dep_platforms, **options.merge(dependency: dep))
+
+          dep
+        end
+      end
+
+      def [](name)
+        @base[name]
+      end
+
+      def delete(specs)
+        @base.delete(specs)
+      end
+
+      def get_package(name)
+        @packages[name]
+      end
+
+      def base_requirements
+        @base_requirements ||= build_base_requirements
+      end
+
+      def unlock_names(names)
+        indirect_pins = indirect_pins(names)
+
+        if indirect_pins.any?
+          loosen_names(indirect_pins)
+        else
+          pins = pins(names)
+
+          if pins.any?
+            loosen_names(pins)
+          else
+            unrestrict_names(names)
+          end
+        end
+      end
+
+      def include_prereleases(names)
+        names.each do |name|
+          get_package(name).consider_prereleases!
+        end
+      end
+
+      def include_remote_specs(names)
+        names.each do |name|
+          get_package(name).consider_remote_versions!
+        end
+      end
+
+      private
+
+      def indirect_pins(names)
+        names.select {|name| @base_requirements[name].exact? && @requirements.none? {|dep| dep.name == name } }
+      end
+
+      def pins(names)
+        names.select {|name| @base_requirements[name].exact? }
+      end
+
+      def loosen_names(names)
+        names.each do |name|
+          version = @base_requirements[name].requirements.first[1]
+
+          @base_requirements[name] = Gem::Requirement.new(">= #{version}")
+
+          @base.delete_by_name(name)
+        end
+      end
+
+      def unrestrict_names(names)
+        names.each do |name|
+          @base_requirements.delete(name)
+        end
+      end
+
+      def build_base_requirements
+        base_requirements = {}
+        @base.each do |ls|
+          if ls.source_changed? && ls.source.specs.search(ls.name).empty?
+            raise GemNotFound, "Could not find gem '#{ls.name}' in #{ls.source}"
+          end
+
+          req = Gem::Requirement.new(ls.version)
+          base_requirements[ls.name] = req
+        end
+        base_requirements
+      end
+    end
+  end
+end
diff --git a/lib/bundler/resolver/candidate.rb b/lib/bundler/resolver/candidate.rb
new file mode 100644
index 0000000000..5298b2530f
--- /dev/null
+++ b/lib/bundler/resolver/candidate.rb
@@ -0,0 +1,85 @@
+# frozen_string_literal: true
+
+require_relative "spec_group"
+
+module Bundler
+  class Resolver
+    #
+    # This class is a PubGrub compatible "Version" class that takes Bundler
+    # resolution complexities into account.
+    #
+    # Each Resolver::Candidate has a underlying `Gem::Version` plus a set of
+    # platforms. For example, 1.1.0-x86_64-linux is a different resolution candidate
+    # from 1.1.0 (generic). This is because different platform variants of the
+    # same gem version can bring different dependencies, so they need to be
+    # considered separately.
+    #
+    # Some candidates may also keep some information explicitly about the
+    # package they refer to. These candidates are referred to as "canonical" and
+    # are used when materializing resolution results back into RubyGems
+    # specifications that can be installed, written to lockfiles, and so on.
+    #
+    class Candidate
+      include Comparable
+
+      attr_reader :version
+
+      def initialize(version, group: nil, priority: -1)
+        @spec_group = group || SpecGroup.new([])
+        @version = Gem::Version.new(version)
+        @priority = priority
+      end
+
+      def dependencies
+        @spec_group.dependencies
+      end
+
+      def to_specs(package, most_specific_locked_platform)
+        return [] if package.meta?
+
+        @spec_group.to_specs(package.force_ruby_platform?, most_specific_locked_platform)
+      end
+
+      def prerelease?
+        @version.prerelease?
+      end
+
+      def segments
+        @version.segments
+      end
+
+      def <=>(other)
+        return unless other.is_a?(self.class)
+
+        version_comparison = version <=> other.version
+        return version_comparison unless version_comparison.zero?
+
+        priority <=> other.priority
+      end
+
+      def ==(other)
+        return unless other.is_a?(self.class)
+
+        version == other.version && priority == other.priority
+      end
+
+      def eql?(other)
+        return unless other.is_a?(self.class)
+
+        version.eql?(other.version) && priority.eql?(other.priority)
+      end
+
+      def hash
+        [@version, @priority].hash
+      end
+
+      def to_s
+        @version.to_s
+      end
+
+      protected
+
+      attr_reader :priority
+    end
+  end
+end
diff --git a/lib/bundler/resolver/incompatibility.rb b/lib/bundler/resolver/incompatibility.rb
new file mode 100644
index 0000000000..4ac1b2e1ea
--- /dev/null
+++ b/lib/bundler/resolver/incompatibility.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Resolver
+    class Incompatibility < PubGrub::Incompatibility
+      attr_reader :extended_explanation
+
+      def initialize(terms, cause:, custom_explanation: nil, extended_explanation: nil)
+        @extended_explanation = extended_explanation
+
+        super(terms, cause: cause, custom_explanation: custom_explanation)
+      end
+    end
+  end
+end
diff --git a/lib/bundler/resolver/package.rb b/lib/bundler/resolver/package.rb
new file mode 100644
index 0000000000..3906be3f57
--- /dev/null
+++ b/lib/bundler/resolver/package.rb
@@ -0,0 +1,95 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Resolver
+    #
+    # Represents a gem being resolved, in a format PubGrub likes.
+    #
+    # The class holds the following information:
+    #
+    # * Platforms this gem will be resolved on.
+    # * The locked version of this gem resolution should favor (if any).
+    # * Whether the gem should be unlocked to its latest version.
+    # * The dependency explicit set in the Gemfile for this gem (if any).
+    #
+    class Package
+      attr_reader :name, :platforms, :dependency, :locked_version
+
+      def initialize(name, platforms, locked_specs:, unlock:, prerelease: false, prefer_local: false, dependency: nil, new_platforms: [])
+        @name = name
+        @platforms = platforms
+        @locked_version = locked_specs.version_for(name)
+        @unlock = unlock
+        @dependency = dependency || Dependency.new(name, @locked_version)
+        @platforms |= [Gem::Platform::RUBY] if @dependency.default_force_ruby_platform
+        @top_level = !dependency.nil?
+        @prerelease = @dependency.prerelease? || @locked_version&.prerelease? || prerelease ? :consider_first : :ignore
+        @prefer_local = prefer_local
+        @new_platforms = new_platforms
+      end
+
+      def platform_specs(specs)
+        platforms.map do |platform|
+          prefer_locked = @new_platforms.include?(platform) ? false : !unlock?
+          MatchPlatform.select_best_platform_match(specs, platform, prefer_locked: prefer_locked)
+        end
+      end
+
+      def to_s
+        @name.delete("\0")
+      end
+
+      def root?
+        false
+      end
+
+      def top_level?
+        @top_level
+      end
+
+      def meta?
+        @name.end_with?("\0")
+      end
+
+      def ==(other)
+        self.class == other.class && @name == other.name
+      end
+
+      def hash
+        @name.hash
+      end
+
+      def unlock?
+        @unlock == true || @unlock.include?(name)
+      end
+
+      def ignores_prereleases?
+        @prerelease == :ignore
+      end
+
+      def prerelease_specified?
+        @prerelease == :consider_first
+      end
+
+      def consider_prereleases!
+        @prerelease = :consider_last
+      end
+
+      def prefer_local?
+        @prefer_local
+      end
+
+      def consider_remote_versions!
+        @prefer_local = false
+      end
+
+      def force_ruby_platform?
+        @dependency.force_ruby_platform
+      end
+
+      def current_platform?
+        @dependency.current_platform?
+      end
+    end
+  end
+end
diff --git a/lib/bundler/resolver/root.rb b/lib/bundler/resolver/root.rb
new file mode 100644
index 0000000000..e5eb634fb8
--- /dev/null
+++ b/lib/bundler/resolver/root.rb
@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+require_relative "package"
+
+module Bundler
+  class Resolver
+    #
+    # Represents the Gemfile from the resolver's perspective. It's the root
+    # package and Gemfile entries depend on it.
+    #
+    class Root < Package
+      def initialize(name)
+        @name = name
+      end
+
+      def meta?
+        true
+      end
+
+      def root?
+        true
+      end
+    end
+  end
+end
diff --git a/lib/bundler/resolver/spec_group.rb b/lib/bundler/resolver/spec_group.rb
new file mode 100644
index 0000000000..ac6ba86c4c
--- /dev/null
+++ b/lib/bundler/resolver/spec_group.rb
@@ -0,0 +1,74 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Resolver
+    class SpecGroup
+      attr_reader :specs
+
+      def initialize(specs)
+        @specs = specs
+      end
+
+      def empty?
+        @specs.empty?
+      end
+
+      def name
+        @name ||= exemplary_spec.name
+      end
+
+      def version
+        @version ||= exemplary_spec.version
+      end
+
+      def source
+        @source ||= exemplary_spec.source
+      end
+
+      def to_specs(force_ruby_platform, most_specific_locked_platform)
+        @specs.map do |s|
+          lazy_spec = LazySpecification.from_spec(s)
+          lazy_spec.force_ruby_platform = force_ruby_platform
+          lazy_spec.most_specific_locked_platform = most_specific_locked_platform
+          lazy_spec
+        end
+      end
+
+      def to_s
+        sorted_spec_names.join(", ")
+      end
+
+      def dependencies
+        @dependencies ||= @specs.flat_map(&:expanded_dependencies).uniq.sort
+      end
+
+      def ==(other)
+        sorted_spec_names == other.sorted_spec_names
+      end
+
+      def merge(other)
+        return false unless equivalent?(other)
+
+        @specs |= other.specs
+
+        true
+      end
+
+      protected
+
+      def sorted_spec_names
+        @specs.map(&:full_name).sort
+      end
+
+      private
+
+      def equivalent?(other)
+        name == other.name && version == other.version && source == other.source && dependencies == other.dependencies
+      end
+
+      def exemplary_spec
+        @specs.first
+      end
+    end
+  end
+end
diff --git a/lib/bundler/resolver/strategy.rb b/lib/bundler/resolver/strategy.rb
new file mode 100644
index 0000000000..7519d38968
--- /dev/null
+++ b/lib/bundler/resolver/strategy.rb
@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Resolver
+    class Strategy
+      def initialize(source)
+        @source = source
+        @package_priority_cache = {}
+      end
+
+      def next_package_and_version(unsatisfied)
+        package, range = next_term_to_try_from(unsatisfied)
+
+        [package, most_preferred_version_of(package, range).first]
+      end
+
+      private
+
+      def next_term_to_try_from(unsatisfied)
+        unsatisfied.min_by do |package, range|
+          @package_priority_cache[[package, range]] ||= begin
+            matching_versions = @source.versions_for(package, range)
+            higher_versions = @source.versions_for(package, range.upper_invert)
+
+            [matching_versions.count <= 1 ? 0 : 1, higher_versions.count]
+          end
+        end
+      end
+
+      def most_preferred_version_of(package, range)
+        versions = @source.versions_for(package, range)
+
+        # Conditional avoids (among other things) calling
+        # sort_versions_by_preferred with the root package
+        if versions.size > 1
+          @source.sort_versions_by_preferred(package, versions)
+        else
+          versions
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/retry.rb b/lib/bundler/retry.rb
new file mode 100644
index 0000000000..49b0f63838
--- /dev/null
+++ b/lib/bundler/retry.rb
@@ -0,0 +1,92 @@
+# frozen_string_literal: true
+
+module Bundler
+  # General purpose class for retrying code that may fail
+  class Retry
+    attr_accessor :name, :total_runs, :current_run
+
+    class << self
+      attr_accessor :default_base_delay
+
+      def default_attempts
+        default_retries + 1
+      end
+      alias_method :attempts, :default_attempts
+
+      def default_retries
+        Bundler.settings[:retry]
+      end
+    end
+
+    # Set default base delay for exponential backoff
+    self.default_base_delay = 1.0
+
+    def initialize(name, exceptions = nil, retries = self.class.default_retries, opts = {})
+      @name = name
+      @retries = retries
+      @exceptions = Array(exceptions) || []
+      @total_runs = @retries + 1 # will run once, then upto attempts.times
+      @base_delay = opts[:base_delay] || self.class.default_base_delay
+      @max_delay = opts[:max_delay] || 60.0
+      @jitter = opts[:jitter] || 0.5
+    end
+
+    def attempt(&block)
+      @current_run = 0
+      @failed      = false
+      @error       = nil
+      run(&block) while keep_trying?
+      @result
+    end
+    alias_method :attempts, :attempt
+
+    private
+
+    def run(&block)
+      @failed = false
+      @current_run += 1
+      @result = block.call
+    rescue StandardError => e
+      fail_attempt(e)
+    end
+
+    def fail_attempt(e)
+      @failed = true
+      if last_attempt? || @exceptions.any? {|k| e.is_a?(k) }
+        Bundler.ui.info "" unless Bundler.ui.debug?
+        raise e
+      end
+      if name
+        Bundler.ui.info "" unless Bundler.ui.debug? # Add new line in case dots preceded this
+        Bundler.ui.warn "Retrying #{name} due to error (#{current_run.next}/#{total_runs}): #{e.class} #{e.message}", true
+      end
+      backoff_sleep if @base_delay > 0
+      true
+    end
+
+    def backoff_sleep
+      # Exponential backoff: delay = base_delay * 2^(attempt - 1)
+      # Add jitter to prevent thundering herd: random value between 0 and jitter seconds
+      delay = @base_delay * (2**(@current_run - 1))
+      delay = [@max_delay, delay].min
+      jitter_amount = rand * @jitter
+      total_delay = delay + jitter_amount
+      Bundler.ui.debug "Sleeping for #{total_delay.round(2)} seconds before retry"
+      sleep(total_delay)
+    end
+
+    def sleep(duration)
+      Kernel.sleep(duration)
+    end
+
+    def keep_trying?
+      return true  if current_run.zero?
+      return false if last_attempt?
+      true if @failed
+    end
+
+    def last_attempt?
+      current_run >= total_runs
+    end
+  end
+end
diff --git a/lib/bundler/ruby_dsl.rb b/lib/bundler/ruby_dsl.rb
new file mode 100644
index 0000000000..5e52f38c8f
--- /dev/null
+++ b/lib/bundler/ruby_dsl.rb
@@ -0,0 +1,67 @@
+# frozen_string_literal: true
+
+module Bundler
+  module RubyDsl
+    def ruby(*ruby_version)
+      options = ruby_version.pop if ruby_version.last.is_a?(Hash)
+      ruby_version.flatten!
+
+      if options
+        patchlevel = options[:patchlevel]
+        engine = options[:engine]
+        engine_version = options[:engine_version]
+
+        raise GemfileError, "Please define :engine_version" if engine && engine_version.nil?
+        raise GemfileError, "Please define :engine" if engine_version && engine.nil?
+
+        if options[:file]
+          raise GemfileError, "Do not pass version argument when using :file option" unless ruby_version.empty?
+          ruby_version << normalize_ruby_file(options[:file])
+        end
+
+        if engine == "ruby" && engine_version && ruby_version != Array(engine_version)
+          raise GemfileEvalError, "ruby_version must match the :engine_version for MRI"
+        end
+      end
+
+      @ruby_version = RubyVersion.new(ruby_version, patchlevel, engine, engine_version)
+    end
+
+    # Support the various file formats found in .ruby-version files.
+    #
+    #     3.2.2
+    #     ruby-3.2.2
+    #
+    # Also supports .tool-versions files for asdf. Lines not starting with "ruby" are ignored.
+    #
+    #     ruby 2.5.1 # comment is ignored
+    #     ruby   2.5.1# close comment and extra spaces doesn't confuse
+    #
+    # Intentionally does not support `3.2.1@gemset` since rvm recommends using .ruby-gemset instead
+    #
+    # Loads the file relative to the dirname of the Gemfile itself.
+    def normalize_ruby_file(filename)
+      file_content = Bundler.read_file(gemfile.dirname.join(filename))
+      # match "ruby-3.2.2", ruby = "3.2.2", ruby = '3.2.2' or "ruby   3.2.2" capturing version string up to the first space or comment
+      version_match = /^               # Start of line
+                      ruby             # Literal "ruby"
+                      [\s-]*           # Optional whitespace or hyphens (for "ruby-3.2.2" format)
+                      (?:=\s*)?        # Optional equals sign with whitespace (for ruby = "3.2.2" format)
+                      (?:
+                        "([^"]+)"      # Double quoted version
+                        |
+                        '([^']+)'      # Single quoted version
+                        |
+                        ([^\s#"']+)    # Unquoted version
+                      )
+                      /x.match(file_content)
+      if version_match
+        version_match[1] || version_match[2] || version_match[3]
+      else
+        file_content.strip
+      end
+    rescue Errno::ENOENT
+      raise GemfileError, "Could not find version file #{filename}"
+    end
+  end
+end
diff --git a/lib/bundler/ruby_version.rb b/lib/bundler/ruby_version.rb
new file mode 100644
index 0000000000..aeff07582e
--- /dev/null
+++ b/lib/bundler/ruby_version.rb
@@ -0,0 +1,133 @@
+# frozen_string_literal: true
+
+module Bundler
+  class RubyVersion
+    attr_reader :versions,
+      :patchlevel,
+      :engine,
+      :engine_versions,
+      :gem_version,
+      :engine_gem_version
+
+    def initialize(versions, patchlevel, engine, engine_version)
+      # The parameters to this method must satisfy the
+      # following constraints, which are verified in
+      # the DSL:
+      #
+      # * If an engine is specified, an engine version
+      #   must also be specified
+      # * If an engine version is specified, an engine
+      #   must also be specified
+      # * If the engine is "ruby", the engine version
+      #   must not be specified, or the engine version
+      #   specified must match the version.
+
+      @versions = Array(versions).map do |v|
+        normalized_v = normalize_version(v)
+
+        unless Gem::Requirement::PATTERN.match?(normalized_v)
+          raise InvalidArgumentError, "#{v} is not a valid requirement on the Ruby version"
+        end
+
+        op, v = Gem::Requirement.parse(normalized_v)
+        op == "=" ? v.to_s : "#{op} #{v}"
+      end
+
+      @gem_version        = Gem::Requirement.create(@versions.first).requirements.first.last
+      @input_engine       = engine&.to_s
+      @engine             = engine&.to_s || "ruby"
+      @engine_versions    = (engine_version && Array(engine_version)) || @versions
+      @engine_gem_version = Gem::Requirement.create(@engine_versions.first).requirements.first.last
+      @patchlevel         = patchlevel || (@gem_version.prerelease? ? "-1" : nil)
+    end
+
+    def to_s(versions = self.versions)
+      output = String.new("ruby #{versions_string(versions)}")
+      output << " (#{engine} #{versions_string(engine_versions)})" unless engine == "ruby"
+
+      output
+    end
+
+    # @private
+    PATTERN = /
+      ruby\s
+      (\d+\.\d+\.\d+(?:\.\S+)?) # ruby version
+      (?:p(-?\d+))? # optional patchlevel
+      (?:\s\((\S+)\s(.+)\))? # optional engine info
+    /xo
+
+    # Returns a RubyVersion from the given string.
+    # @param [String] the version string to match.
+    # @return [RubyVersion,Nil] The version if the string is a valid RubyVersion
+    #         description, and nil otherwise.
+    def self.from_string(string)
+      new($1, $2, $3, $4) if string =~ PATTERN
+    end
+
+    def single_version_string
+      to_s(gem_version)
+    end
+
+    def ==(other)
+      versions == other.versions &&
+        engine == other.engine &&
+        engine_versions == other.engine_versions
+    end
+
+    def host
+      @host ||= [
+        RbConfig::CONFIG["host_cpu"],
+        RbConfig::CONFIG["host_vendor"],
+        RbConfig::CONFIG["host_os"],
+      ].join("-")
+    end
+
+    # Returns a tuple of these things:
+    #   [diff, this, other]
+    #   The priority of attributes are
+    #   1. engine
+    #   2. ruby_version
+    #   3. engine_version
+    def diff(other)
+      raise ArgumentError, "Can only diff with a RubyVersion, not a #{other.class}" unless other.is_a?(RubyVersion)
+      if engine != other.engine && @input_engine
+        [:engine, engine, other.engine]
+      elsif versions.empty? || !matches?(versions, other.gem_version)
+        [:version, versions_string(versions), versions_string(other.versions)]
+      elsif @input_engine && !matches?(engine_versions, other.engine_gem_version)
+        [:engine_version, versions_string(engine_versions), versions_string(other.engine_versions)]
+      end
+    end
+
+    def versions_string(versions)
+      Array(versions).join(", ")
+    end
+
+    def self.system
+      ruby_engine = RUBY_ENGINE.dup
+      ruby_version = Gem.ruby_version.to_s
+      ruby_engine_version = RUBY_ENGINE == "ruby" ? ruby_version : RUBY_ENGINE_VERSION.dup
+      patchlevel = RUBY_PATCHLEVEL.to_s
+
+      @system ||= RubyVersion.new(ruby_version, patchlevel, ruby_engine, ruby_engine_version)
+    end
+
+    private
+
+    # Ruby's official preview version format uses a `-`: Example: 3.3.0-preview2
+    # However, RubyGems recognizes preview version format with a `.`: Example: 3.3.0.preview2
+    # Returns version string after replacing `-` with `.`
+    def normalize_version(version)
+      version.tr("-", ".")
+    end
+
+    def matches?(requirements, version)
+      # Handles RUBY_PATCHLEVEL of -1 for instances like ruby-head
+      return requirements == version if requirements.to_s == "-1" || version.to_s == "-1"
+
+      Array(requirements).all? do |requirement|
+        Gem::Requirement.create(requirement).satisfied_by?(Gem::Version.create(version))
+      end
+    end
+  end
+end
diff --git a/lib/bundler/rubygems_ext.rb b/lib/bundler/rubygems_ext.rb
new file mode 100644
index 0000000000..4ad2bdf46f
--- /dev/null
+++ b/lib/bundler/rubygems_ext.rb
@@ -0,0 +1,503 @@
+# frozen_string_literal: true
+
+require "rubygems" unless defined?(Gem)
+
+# We can't let `Gem::Source` be autoloaded in the `Gem::Specification#source`
+# redefinition below, so we need to load it upfront. The reason is that if
+# Bundler monkeypatches are loaded before RubyGems activates an executable (for
+# example, through `ruby -rbundler -S irb`), gem activation might end up calling
+# the redefined `Gem::Specification#source` and triggering the `Gem::Source`
+# autoload. That would result in requiring "rubygems/source" inside another
+# require, which would trigger a monitor error and cause the `autoload` to
+# eventually fail. A better solution is probably to completely avoid autoloading
+# `Gem::Source` from the redefined `Gem::Specification#source`.
+require "rubygems/source"
+
+module Gem
+  # Can be removed once RubyGems 3.5.11 support is dropped
+  unless Gem.respond_to?(:freebsd_platform?)
+    def self.freebsd_platform?
+      RbConfig::CONFIG["host_os"].to_s.include?("bsd")
+    end
+  end
+
+  # Can be removed once RubyGems 3.5.18 support is dropped
+  unless Gem.respond_to?(:open_file_with_lock)
+    class << self
+      remove_method :open_file_with_flock if Gem.respond_to?(:open_file_with_flock)
+
+      def open_file_with_flock(path, &block)
+        # read-write mode is used rather than read-only in order to support NFS
+        mode = IO::RDWR | IO::APPEND | IO::CREAT | IO::BINARY
+        mode |= IO::SHARE_DELETE if IO.const_defined?(:SHARE_DELETE)
+
+        File.open(path, mode) do |io|
+          begin
+            io.flock(File::LOCK_EX)
+          rescue Errno::ENOSYS, Errno::ENOTSUP
+          end
+          yield io
+        end
+      end
+
+      def open_file_with_lock(path, &block)
+        file_lock = "#{path}.lock"
+        open_file_with_flock(file_lock, &block)
+      ensure
+        FileUtils.rm_f file_lock
+      end
+    end
+  end
+
+  require "rubygems/platform"
+
+  class Platform
+    # Can be removed once RubyGems 3.6.9 support is dropped
+    unless respond_to?(:generic)
+      JAVA  = Gem::Platform.new("java") # :nodoc:
+      MSWIN = Gem::Platform.new("mswin32") # :nodoc:
+      MSWIN64 = Gem::Platform.new("mswin64") # :nodoc:
+      MINGW = Gem::Platform.new("x86-mingw32") # :nodoc:
+      X64_MINGW_LEGACY = Gem::Platform.new("x64-mingw32") # :nodoc:
+      X64_MINGW = Gem::Platform.new("x64-mingw-ucrt") # :nodoc:
+      UNIVERSAL_MINGW = Gem::Platform.new("universal-mingw") # :nodoc:
+      WINDOWS = [MSWIN, MSWIN64, UNIVERSAL_MINGW].freeze # :nodoc:
+      X64_LINUX = Gem::Platform.new("x86_64-linux") # :nodoc:
+      X64_LINUX_MUSL = Gem::Platform.new("x86_64-linux-musl") # :nodoc:
+
+      GENERICS = [JAVA, *WINDOWS].freeze # :nodoc:
+      private_constant :GENERICS
+
+      GENERIC_CACHE = GENERICS.each_with_object({}) {|g, h| h[g] = g } # :nodoc:
+      private_constant :GENERIC_CACHE
+
+      class << self
+        ##
+        # Returns the generic platform for the given platform.
+
+        def generic(platform)
+          return Gem::Platform::RUBY if platform.nil? || platform == Gem::Platform::RUBY
+
+          GENERIC_CACHE[platform] ||= begin
+            found = GENERICS.find do |match|
+              platform === match
+            end
+            found || Gem::Platform::RUBY
+          end
+        end
+
+        ##
+        # Returns the platform specificity match for the given spec platform and user platform.
+
+        def platform_specificity_match(spec_platform, user_platform)
+          return -1 if spec_platform == user_platform
+          return 1_000_000 if spec_platform.nil? || spec_platform == Gem::Platform::RUBY || user_platform == Gem::Platform::RUBY
+
+          os_match(spec_platform, user_platform) +
+            cpu_match(spec_platform, user_platform) * 10 +
+            version_match(spec_platform, user_platform) * 100
+        end
+
+        ##
+        # Sorts and filters the best platform match for the given matching specs and platform.
+
+        def sort_and_filter_best_platform_match(matching, platform)
+          return matching if matching.one?
+
+          exact = matching.select {|spec| spec.platform == platform }
+          return exact if exact.any?
+
+          sorted_matching = sort_best_platform_match(matching, platform)
+          exemplary_spec = sorted_matching.first
+
+          sorted_matching.take_while {|spec| same_specificity?(platform, spec, exemplary_spec) && same_deps?(spec, exemplary_spec) }
+        end
+
+        ##
+        # Sorts the best platform match for the given matching specs and platform.
+
+        def sort_best_platform_match(matching, platform)
+          matching.sort_by.with_index do |spec, i|
+            [
+              platform_specificity_match(spec.platform, platform),
+              i, # for stable sort
+            ]
+          end
+        end
+
+        private
+
+        def same_specificity?(platform, spec, exemplary_spec)
+          platform_specificity_match(spec.platform, platform) == platform_specificity_match(exemplary_spec.platform, platform)
+        end
+
+        def same_deps?(spec, exemplary_spec)
+          spec.required_ruby_version == exemplary_spec.required_ruby_version &&
+            spec.required_rubygems_version == exemplary_spec.required_rubygems_version &&
+            spec.dependencies.sort == exemplary_spec.dependencies.sort
+        end
+
+        def os_match(spec_platform, user_platform)
+          if spec_platform.os == user_platform.os
+            0
+          else
+            1
+          end
+        end
+
+        def cpu_match(spec_platform, user_platform)
+          if spec_platform.cpu == user_platform.cpu
+            0
+          elsif spec_platform.cpu == "arm" && user_platform.cpu.to_s.start_with?("arm")
+            0
+          elsif spec_platform.cpu.nil? || spec_platform.cpu == "universal"
+            1
+          else
+            2
+          end
+        end
+
+        def version_match(spec_platform, user_platform)
+          if spec_platform.version == user_platform.version
+            0
+          elsif spec_platform.version.nil?
+            1
+          else
+            2
+          end
+        end
+      end
+
+    end
+  end
+
+  require "rubygems/specification"
+
+  # Can be removed once RubyGems 3.5.14 support is dropped
+  VALIDATES_FOR_RESOLUTION = Specification.new.respond_to?(:validate_for_resolution).freeze
+
+  class Specification
+    # Can be removed once RubyGems 3.5.15 support is dropped
+    correct_array_attributes = @@default_value.select {|_k,v| v.is_a?(Array) }.keys
+    unless @@array_attributes == correct_array_attributes
+      @@array_attributes = correct_array_attributes # rubocop:disable Style/ClassVars
+    end
+
+    require_relative "match_metadata"
+    require_relative "match_platform"
+
+    include ::Bundler::MatchMetadata
+
+    attr_accessor :remote, :relative_loaded_from
+
+    module AllowSettingSource
+      attr_writer :source
+
+      def source
+        (defined?(@source) && @source) || super
+      end
+    end
+
+    prepend AllowSettingSource
+
+    alias_method :rg_full_gem_path, :full_gem_path
+    alias_method :rg_loaded_from,   :loaded_from
+
+    def full_gem_path
+      if source.respond_to?(:root)
+        File.expand_path(File.dirname(loaded_from), source.root)
+      else
+        rg_full_gem_path
+      end
+    end
+
+    def loaded_from
+      if relative_loaded_from
+        source.path.join(relative_loaded_from).to_s
+      else
+        rg_loaded_from
+      end
+    end
+
+    def load_paths
+      full_require_paths
+    end
+
+    alias_method :rg_extension_dir, :extension_dir
+    def extension_dir
+      # following instance variable is already used in original method
+      # and that is the reason to prefix it with bundler_ and add rubocop exception
+      @bundler_extension_dir ||= if source.respond_to?(:extension_dir_name) # rubocop:disable Naming/MemoizedInstanceVariableName
+        unique_extension_dir = [source.extension_dir_name, File.basename(full_gem_path)].uniq.join("-")
+        File.expand_path(File.join(extensions_dir, unique_extension_dir))
+      else
+        rg_extension_dir
+      end
+    end
+
+    # Can be removed once RubyGems 3.5.21 support is dropped
+    remove_method :gem_dir if method_defined?(:gem_dir, false)
+
+    def gem_dir
+      full_gem_path
+    end
+
+    def insecurely_materialized?
+      false
+    end
+
+    def groups
+      @groups ||= []
+    end
+
+    def git_version
+      return unless loaded_from && source.is_a?(Bundler::Source::Git)
+      " #{source.revision[0..6]}"
+    end
+
+    def to_gemfile(path = nil)
+      gemfile = String.new("source 'https://rubygems.org'\n")
+      gemfile << dependencies_to_gemfile(nondevelopment_dependencies)
+      unless development_dependencies.empty?
+        gemfile << "\n"
+        gemfile << dependencies_to_gemfile(development_dependencies, :development)
+      end
+      gemfile
+    end
+
+    def nondevelopment_dependencies
+      dependencies - development_dependencies
+    end
+
+    def installation_missing?
+      !default_gem? && !File.directory?(full_gem_path)
+    end
+
+    def lock_name
+      @lock_name ||= name_tuple.lock_name
+    end
+
+    unless VALIDATES_FOR_RESOLUTION
+      def validate_for_resolution
+        SpecificationPolicy.new(self).validate_for_resolution
+      end
+    end
+
+    if Gem.rubygems_version < Gem::Version.new("3.5.22")
+      module FixPathSourceMissingExtensions
+        def missing_extensions?
+          return false if %w[Bundler::Source::Path Bundler::Source::Gemspec].include?(source.class.name)
+
+          super
+        end
+      end
+
+      prepend FixPathSourceMissingExtensions
+    end
+
+    private
+
+    def dependencies_to_gemfile(dependencies, group = nil)
+      gemfile = String.new
+      if dependencies.any?
+        gemfile << "group :#{group} do\n" if group
+        dependencies.each do |dependency|
+          gemfile << "  " if group
+          gemfile << %(gem "#{dependency.name}")
+          req = dependency.requirements_list.first
+          gemfile << %(, "#{req}") if req
+          gemfile << "\n"
+        end
+        gemfile << "end\n" if group
+      end
+      gemfile
+    end
+  end
+
+  unless VALIDATES_FOR_RESOLUTION
+    class SpecificationPolicy
+      def validate_for_resolution
+        validate_required!
+      end
+    end
+  end
+
+  module BetterPermissionError
+    def data
+      super
+    rescue Errno::EACCES
+      raise Bundler::PermissionError.new(loaded_from, :read)
+    end
+  end
+
+  require "rubygems/stub_specification"
+
+  class StubSpecification
+    prepend BetterPermissionError
+  end
+
+  class Dependency
+    require_relative "force_platform"
+
+    include ::Bundler::ForcePlatform
+
+    attr_reader :force_ruby_platform
+
+    attr_accessor :source, :groups
+
+    alias_method :eql?, :==
+
+    unless method_defined?(:encode_with, false)
+      def encode_with(coder)
+        [:@name, :@requirement, :@type, :@prerelease, :@version_requirements].each do |ivar|
+          coder[ivar.to_s.sub(/^@/, "")] = instance_variable_get(ivar)
+        end
+      end
+    end
+
+    def to_lock
+      out = String.new("  #{name}")
+      unless requirement.none?
+        reqs = requirement.requirements.map {|o, v| "#{o} #{v}" }.sort.reverse
+        out << " (#{reqs.join(", ")})"
+      end
+      out
+    end
+
+    if Gem.rubygems_version < Gem::Version.new("3.5.22")
+      module FilterIgnoredSpecs
+        def matching_specs(platform_only = false)
+          super.reject(&:ignored?)
+        end
+      end
+
+      prepend FilterIgnoredSpecs
+    end
+  end
+
+  # On universal Rubies, resolve the "universal" arch to the real CPU arch, without changing the extension directory.
+  class BasicSpecification
+    if /^universal\.(?<arch>.*?)-/ =~ (CROSS_COMPILING || RUBY_PLATFORM)
+      local_platform = Platform.local
+      if local_platform.cpu == "universal"
+        ORIGINAL_LOCAL_PLATFORM = local_platform.to_s.freeze
+
+        local_platform.cpu = if arch == "arm64e" # arm64e is only permitted for Apple system binaries
+          "arm64"
+        else
+          arch
+        end
+
+        def extensions_dir
+          @extensions_dir ||=
+            Gem.default_ext_dir_for(base_dir) || File.join(base_dir, "extensions", ORIGINAL_LOCAL_PLATFORM, Gem.extension_api_version)
+        end
+      end
+    end
+
+    # Can be removed once RubyGems 3.5.22 support is dropped
+    unless new.respond_to?(:ignored?)
+      def ignored?
+        return @ignored unless @ignored.nil?
+
+        @ignored = missing_extensions?
+      end
+    end
+
+    # Can be removed once RubyGems 3.6.9 support is dropped
+    unless new.respond_to?(:installable_on_platform?)
+      include(::Bundler::MatchPlatform)
+    end
+  end
+
+  require "rubygems/name_tuple"
+
+  class NameTuple
+    # Versions of RubyGems before about 3.5.0 don't to_s the platform.
+    unless Gem::NameTuple.new("a", Gem::Version.new("1"), Gem::Platform.new("x86_64-linux")).platform.is_a?(String)
+      alias_method :initialize_with_platform, :initialize
+
+      def initialize(name, version, platform = Gem::Platform::RUBY)
+        if Gem::Platform === platform
+          initialize_with_platform(name, version, platform.to_s)
+        else
+          initialize_with_platform(name, version, platform)
+        end
+      end
+    end
+
+    def lock_name
+      if platform == Gem::Platform::RUBY
+        "#{name} (#{version})"
+      else
+        "#{name} (#{version}-#{platform})"
+      end
+    end
+  end
+
+  unless Gem.rubygems_version >= Gem::Version.new("3.5.19")
+    class Resolver::ActivationRequest
+      remove_method :installed?
+
+      def installed?
+        case @spec
+        when Gem::Resolver::VendorSpecification then
+          true
+        else
+          this_spec = full_spec
+
+          Gem::Specification.any? do |s|
+            s == this_spec && s.base_dir == this_spec.base_dir
+          end
+        end
+      end
+    end
+  end
+
+  unless Gem.rubygems_version >= Gem::Version.new("3.6.7")
+    module UnfreezeCompactIndexParsedResponse
+      def parse(line)
+        version, platform, dependencies, requirements = super
+        [version, platform, dependencies.frozen? ? dependencies.dup : dependencies, requirements.frozen? ? requirements.dup : requirements]
+      end
+    end
+
+    Resolver::APISet::GemParser.prepend(UnfreezeCompactIndexParsedResponse)
+  end
+
+  # RubyGems before 4.0.13 split compact index dependency/requirement entries
+  # on every colon, which mangles metadata values that contain colons such as
+  # the `created_at` timestamps the cooldown feature relies on. Split only on
+  # the first colon so those values survive on older RubyGems.
+  #
+  # The module is defined unconditionally so it stays testable on any RubyGems,
+  # but only prepended when the host RubyGems still has the buggy behavior.
+  module SplitCompactIndexEntryOnFirstColon
+    private
+
+    def parse_dependency(string)
+      dependency = string.split(":", 2)
+      dependency[-1] = dependency[-1].split("&") if dependency.size > 1
+      dependency[0] = -dependency[0]
+      dependency
+    end
+  end
+
+  unless Gem.rubygems_version >= Gem::Version.new("4.0.13")
+    Resolver::APISet::GemParser.prepend(SplitCompactIndexEntryOnFirstColon)
+  end
+
+  if Gem.rubygems_version < Gem::Version.new("3.6.0")
+    class Package; end
+    require "rubygems/package/tar_reader"
+    require "rubygems/package/tar_reader/entry"
+
+    module FixFullNameEncoding
+      def full_name
+        super.force_encoding(Encoding::UTF_8)
+      end
+    end
+
+    Package::TarReader::Entry.prepend(FixFullNameEncoding)
+  end
+end
diff --git a/lib/bundler/rubygems_gem_installer.rb b/lib/bundler/rubygems_gem_installer.rb
new file mode 100644
index 0000000000..fc019f54d2
--- /dev/null
+++ b/lib/bundler/rubygems_gem_installer.rb
@@ -0,0 +1,196 @@
+# frozen_string_literal: true
+
+require "rubygems/installer"
+
+module Bundler
+  class RubyGemsGemInstaller < Gem::Installer
+    def check_executable_overwrite(filename)
+      # Bundler needs to install gems regardless of binstub overwriting
+    end
+
+    def install
+      pre_install_checks
+
+      run_pre_install_hooks
+
+      spec.loaded_from = spec_file
+
+      # Completely remove any previous gem files
+      strict_rm_rf gem_dir
+      strict_rm_rf spec.extension_dir
+
+      SharedHelpers.filesystem_access(gem_dir, :create) do
+        FileUtils.mkdir_p gem_dir
+      end
+
+      SharedHelpers.filesystem_access(gem_dir, :write) do
+        extract_files
+      end
+
+      if options[:build_extension] == false
+        warn_skipped_extensions
+      elsif spec.extensions.any?
+        build_extensions
+      end
+      write_build_info_file
+      run_post_build_hooks
+
+      SharedHelpers.filesystem_access(bin_dir, :write) do
+        generate_bin
+      end
+
+      if options[:install_plugin] == false
+        remove_stale_plugins
+        warn_skipped_plugins
+      else
+        generate_plugins
+      end
+
+      write_spec
+
+      SharedHelpers.filesystem_access("#{gem_home}/cache", :write) do
+        write_cache_file
+      end
+
+      say spec.post_install_message unless spec.post_install_message.nil?
+
+      run_post_install_hooks
+
+      spec
+    end
+
+    if Bundler.rubygems.provides?("< 3.5")
+      def pre_install_checks
+        super
+      rescue Gem::FilePermissionError
+        # Ignore permission checks in RubyGems. Instead, go on, and try to write
+        # for real. We properly handle permission errors when they happen.
+        nil
+      end
+    end
+
+    def ensure_writable_dir(dir)
+      super
+    rescue Gem::FilePermissionError
+      # Ignore permission checks in RubyGems. Instead, go on, and try to write
+      # for real. We properly handle permission errors when they happen.
+      nil
+    end
+
+    def generate_plugins
+      return unless Gem::Installer.method_defined?(:generate_plugins, false)
+
+      ensure_writable_dir @plugins_dir
+
+      if spec.plugins.empty?
+        remove_plugins_for(spec, @plugins_dir)
+      else
+        regenerate_plugins_for(spec, @plugins_dir)
+      end
+    end
+
+    def warn_skipped_extensions
+      return if spec.extensions.empty?
+
+      Bundler.ui.warn "#{spec.full_name} contains native extensions that were not built.\n" \
+                      "To build extensions, unset no_build_extension and run `bundle pristine #{spec.name}`."
+    end
+
+    def warn_skipped_plugins
+      return if spec.plugins.empty?
+
+      Bundler.ui.warn "#{spec.full_name} contains plugins that were not installed.\n" \
+                      "To install plugins, unset no_install_plugin and run `bundle pristine #{spec.name}`."
+    end
+
+    if Bundler.rubygems.provides?("< 3.5.19")
+      def generate_bin_script(filename, bindir)
+        bin_script_path = File.join bindir, formatted_program_filename(filename)
+
+        Gem.open_file_with_lock(bin_script_path) do
+          require "fileutils"
+          FileUtils.rm_f bin_script_path # prior install may have been --no-wrappers
+
+          File.open(bin_script_path, "wb", 0o755) do |file|
+            file.write app_script_text(filename)
+            file.chmod(options[:prog_mode] || 0o755)
+          end
+        end
+
+        verbose bin_script_path
+
+        generate_windows_script filename, bindir
+      end
+    end
+
+    def build_jobs
+      Bundler.settings[:jobs] || super
+    end
+
+    def build_extensions
+      extension_cache_path = options[:bundler_extension_cache_path]
+      extension_dir = spec.extension_dir
+      unless extension_cache_path && extension_dir
+        prepare_extension_build(extension_dir)
+        return super
+      end
+
+      build_complete = SharedHelpers.filesystem_access(extension_cache_path.join("gem.build_complete"), :read, &:file?)
+      if build_complete && !options[:force]
+        SharedHelpers.filesystem_access(File.dirname(extension_dir)) do |p|
+          FileUtils.mkpath p
+        end
+        SharedHelpers.filesystem_access(extension_cache_path) do
+          FileUtils.cp_r extension_cache_path, extension_dir
+        end
+      else
+        prepare_extension_build(extension_dir)
+        super
+        SharedHelpers.filesystem_access(extension_cache_path.parent, &:mkpath)
+        SharedHelpers.filesystem_access(extension_cache_path) do
+          FileUtils.cp_r extension_dir, extension_cache_path
+        end
+      end
+    end
+
+    def spec
+      if Bundler.rubygems.provides?("< 3.3.12") # RubyGems implementation rescues and re-raises errors before 3.3.12 and we don't want that
+        @package.spec
+      else
+        super
+      end
+    end
+
+    def gem_checksum
+      Checksum.from_gem_package(@package)
+    end
+
+    private
+
+    def prepare_extension_build(extension_dir)
+      SharedHelpers.filesystem_access(extension_dir, :create) do
+        FileUtils.mkdir_p extension_dir
+      end
+    end
+
+    def strict_rm_rf(dir)
+      return unless File.exist?(dir)
+      return if Dir.empty?(dir)
+
+      parent = File.dirname(dir)
+      parent_st = File.stat(parent)
+
+      if parent_st.world_writable? && !parent_st.sticky?
+        raise InsecureInstallPathError.new(spec.full_name, dir)
+      end
+
+      begin
+        FileUtils.remove_entry_secure(dir)
+      rescue StandardError => e
+        raise unless File.exist?(dir)
+
+        raise DirectoryRemovalError.new(e, "Could not delete previous installation of `#{dir}`")
+      end
+    end
+  end
+end
diff --git a/lib/bundler/rubygems_integration.rb b/lib/bundler/rubygems_integration.rb
new file mode 100644
index 0000000000..e04ef23259
--- /dev/null
+++ b/lib/bundler/rubygems_integration.rb
@@ -0,0 +1,456 @@
+# frozen_string_literal: true
+
+require "rubygems" unless defined?(Gem)
+
+module Bundler
+  class RubygemsIntegration
+    require "monitor"
+
+    EXT_LOCK = Monitor.new
+
+    def initialize
+      @replaced_methods = {}
+    end
+
+    def version
+      @version ||= Gem.rubygems_version
+    end
+
+    def provides?(req_str)
+      Gem::Requirement.new(req_str).satisfied_by?(version)
+    end
+
+    def build_args
+      require "rubygems/command"
+      Gem::Command.build_args
+    end
+
+    def build_args=(args)
+      require "rubygems/command"
+      Gem::Command.build_args = args
+    end
+
+    def set_target_rbconfig(path)
+      Gem.set_target_rbconfig(path)
+    end
+
+    def loaded_specs(name)
+      Gem.loaded_specs[name]
+    end
+
+    def mark_loaded(spec)
+      if spec.respond_to?(:activated=)
+        current = Gem.loaded_specs[spec.name]
+        current.activated = false if current
+        spec.activated = true
+      end
+      Gem.loaded_specs[spec.name] = spec
+    end
+
+    def validate(spec)
+      Bundler.ui.silence { spec.validate_for_resolution }
+    rescue Gem::InvalidSpecificationException => e
+      error_message = "The gemspec at #{spec.loaded_from} is not valid. Please fix this gemspec.\n" \
+        "The validation error was '#{e.message}'\n"
+      raise Gem::InvalidSpecificationException.new(error_message)
+    rescue Errno::ENOENT
+      nil
+    end
+
+    def stub_set_spec(stub, spec)
+      stub.instance_variable_set(:@spec, spec)
+    end
+
+    def path(obj)
+      obj.to_s
+    end
+
+    def ruby_engine
+      Gem.ruby_engine
+    end
+
+    def read_binary(path)
+      Gem.read_binary(path)
+    end
+
+    def inflate(obj)
+      Gem::Util.inflate(obj)
+    end
+
+    def gem_dir
+      Gem.dir
+    end
+
+    def gem_bindir
+      Gem.bindir
+    end
+
+    def user_home
+      Gem.user_home
+    end
+
+    def gem_path
+      Gem.path
+    end
+
+    def reset
+      Gem::Specification.reset
+    end
+
+    def post_reset_hooks
+      Gem.post_reset_hooks
+    end
+
+    def suffix_pattern
+      Gem.suffix_pattern
+    end
+
+    def gem_cache
+      gem_path.map {|p| File.expand_path("cache", p) }
+    end
+
+    def spec_cache_dirs
+      @spec_cache_dirs ||= begin
+        dirs = gem_path.map {|dir| File.join(dir, "specifications") }
+        dirs << Gem.spec_cache_dir
+        dirs.uniq.select {|dir| File.directory? dir }
+      end
+    end
+
+    def marshal_spec_dir
+      Gem::MARSHAL_SPEC_DIR
+    end
+
+    def clear_paths
+      Gem.clear_paths
+    end
+
+    def bin_path(gem, bin, ver)
+      Gem.bin_path(gem, bin, ver)
+    end
+
+    def loaded_gem_paths
+      loaded_gem_paths = Gem.loaded_specs.map {|_, s| s.full_require_paths }
+      loaded_gem_paths.flatten
+    end
+
+    def ui=(obj)
+      Gem::DefaultUserInteraction.ui = obj
+    end
+
+    def ext_lock
+      EXT_LOCK
+    end
+
+    def spec_from_gem(path)
+      require "rubygems/package"
+      Gem::Package.new(path).spec
+    end
+
+    def build_gem(gem_dir, spec)
+      build(spec)
+    end
+
+    def security_policy_keys
+      %w[High Medium Low AlmostNo No].map {|level| "#{level}Security" }
+    end
+
+    def security_policies
+      @security_policies ||= begin
+        require "rubygems/security"
+        Gem::Security::Policies
+      rescue LoadError, NameError
+        {}
+      end
+    end
+
+    def reverse_rubygems_kernel_mixin
+      # Disable rubygems' gem activation system
+      if Gem.respond_to?(:discover_gems_on_require=)
+        Gem.discover_gems_on_require = false
+      else
+        [::Kernel.singleton_class, ::Kernel].each do |k|
+          if k.private_method_defined?(:gem_original_require)
+            redefine_method(k, :require, k.instance_method(:gem_original_require))
+          end
+        end
+      end
+    end
+
+    def replace_gem(specs_by_name)
+      executables = nil
+
+      [::Kernel.singleton_class, ::Kernel].each do |kernel_class|
+        redefine_method(kernel_class, :gem) do |dep, *reqs|
+          if executables&.include?(File.basename(caller_locations(1, 1).first.path))
+            break
+          end
+
+          reqs.pop if reqs.last.is_a?(Hash)
+
+          unless dep.respond_to?(:name) && dep.respond_to?(:requirement)
+            dep = Gem::Dependency.new(dep, reqs)
+          end
+
+          if spec = specs_by_name[dep.name]
+            return true if dep.matches_spec?(spec)
+          end
+
+          message = if spec.nil?
+            target_file = begin
+                            Bundler.default_gemfile.basename
+                          rescue GemfileNotFound
+                            "inline Gemfile"
+                          end
+            "#{dep.name} is not part of the bundle." \
+            " Add it to your #{target_file}."
+          else
+            "can't activate #{dep}, already activated #{spec.full_name}. " \
+            "Make sure all dependencies are added to Gemfile."
+          end
+
+          e = Gem::LoadError.new(message)
+          e.name = dep.name
+          e.requirement = dep.requirement
+          raise e
+        end
+      end
+    end
+
+    # Used to give better error messages when activating specs outside of the current bundle
+    def replace_bin_path(specs_by_name)
+      redefine_method(gem_class, :find_spec_for_exe) do |gem_name, *args|
+        exec_name = args.first
+        raise ArgumentError, "you must supply exec_name" unless exec_name
+
+        spec_with_name = specs_by_name[gem_name]
+        matching_specs_by_exec_name = specs_by_name.values.select {|s| s.executables.include?(exec_name) }
+        spec = matching_specs_by_exec_name.delete(spec_with_name)
+
+        unless spec || !matching_specs_by_exec_name.empty?
+          message = "can't find executable #{exec_name} for gem #{gem_name}"
+          if spec_with_name.nil?
+            message += ". #{gem_name} is not currently included in the bundle, " \
+                       "perhaps you meant to add it to your #{Bundler.default_gemfile.basename}?"
+          end
+          raise Gem::Exception, message
+        end
+
+        unless spec
+          spec = matching_specs_by_exec_name.shift
+          warn \
+            "Bundler is using a binstub that was created for a different gem (#{spec.name}).\n" \
+            "You should run `bundle binstub #{gem_name}` " \
+            "to work around a system/bundle conflict."
+        end
+
+        unless matching_specs_by_exec_name.empty?
+          conflicting_names = matching_specs_by_exec_name.map(&:name).join(", ")
+          warn \
+            "The `#{exec_name}` executable in the `#{spec.name}` gem is being loaded, but it's also present in other gems (#{conflicting_names}).\n" \
+            "If you meant to run the executable for another gem, make sure you use a project specific binstub (`bundle binstub <gem_name>`).\n" \
+            "If you plan to use multiple conflicting executables, generate binstubs for them and disambiguate their names."
+        end
+
+        spec
+      end
+    end
+
+    # Replace or hook into RubyGems to provide a bundlerized view
+    # of the world.
+    def replace_entrypoints(specs)
+      specs_by_name = add_default_gems_to(specs)
+
+      reverse_rubygems_kernel_mixin
+      begin
+        # bundled_gems only provide with Ruby 3.3 or later
+        require "bundled_gems"
+      rescue LoadError
+      else
+        Gem::BUNDLED_GEMS.replace_require(specs) if Gem::BUNDLED_GEMS.respond_to?(:replace_require)
+      end
+      replace_gem(specs_by_name)
+      stub_rubygems(specs_by_name.values)
+      replace_bin_path(specs_by_name)
+
+      Gem.clear_paths
+    end
+
+    # Add default gems not already present in specs, and return them as a hash.
+    def add_default_gems_to(specs)
+      specs_by_name = specs.reduce({}) do |h, s|
+        h[s.name] = s
+        h
+      end
+
+      Bundler.rubygems.default_stubs.each do |stub|
+        default_spec = stub.to_spec
+        default_spec_name = default_spec.name
+        next if specs_by_name.key?(default_spec_name)
+
+        specs_by_name[default_spec_name] = default_spec
+      end
+
+      specs_by_name
+    end
+
+    def undo_replacements
+      @replaced_methods.each do |(sym, klass), method|
+        redefine_method(klass, sym, method)
+      end
+      post_reset_hooks.reject! {|proc| proc.binding.source_location[0] == __FILE__ }
+      @replaced_methods.clear
+    end
+
+    def redefine_method(klass, method, unbound_method = nil, &block)
+      visibility = method_visibility(klass, method)
+      begin
+        if (instance_method = klass.instance_method(method)) && method != :initialize
+          # doing this to ensure we also get private methods
+          klass.send(:remove_method, method)
+        end
+      rescue NameError
+        # method isn't defined
+        nil
+      end
+      @replaced_methods[[method, klass]] = instance_method
+      if unbound_method
+        klass.send(:define_method, method, unbound_method)
+        klass.send(visibility, method)
+      elsif block
+        klass.send(:define_method, method, &block)
+        klass.send(visibility, method)
+      end
+    end
+
+    def method_visibility(klass, method)
+      if klass.private_method_defined?(method)
+        :private
+      elsif klass.protected_method_defined?(method)
+        :protected
+      else
+        :public
+      end
+    end
+
+    def stub_rubygems(specs)
+      Gem::Specification.all = specs
+
+      Gem.post_reset do
+        Gem::Specification.all = specs
+      end
+
+      redefine_method(gem_class, :finish_resolve) do |*|
+        []
+      end
+
+      redefine_method(gem_class, :load_plugins) do |*|
+        load_plugin_files specs.flat_map(&:plugins)
+      end
+    end
+
+    def plain_specs
+      Gem::Specification._all
+    end
+
+    def plain_specs=(specs)
+      Gem::Specification.all = specs
+    end
+
+    def fetch_specs(remote, name, fetcher)
+      require "rubygems/remote_fetcher"
+      path = remote.uri.to_s + "#{name}.#{Gem.marshal_version}.gz"
+      string = fetcher.fetch_path(path)
+      specs = Bundler.safe_load_marshal(string)
+      raise MarshalError, "Specs #{name} from #{remote} is expected to be an Array but was unexpected class #{specs.class}" unless specs.is_a?(Array)
+      specs
+    rescue Gem::RemoteFetcher::FetchError
+      # it's okay for prerelease to fail
+      raise unless name == "prerelease_specs"
+    end
+
+    def fetch_all_remote_specs(remote, gem_remote_fetcher)
+      specs = fetch_specs(remote, "specs", gem_remote_fetcher)
+      pres = fetch_specs(remote, "prerelease_specs", gem_remote_fetcher) || []
+
+      specs.concat(pres)
+    end
+
+    def download_gem(spec, uri, cache_dir, fetcher)
+      require "rubygems/remote_fetcher"
+      uri = Bundler.settings.mirror_for(uri)
+      redacted_uri = Gem::Uri.redact(uri)
+
+      Bundler::Retry.new("download gem from #{redacted_uri}").attempts do
+        gem_file_name = spec.file_name
+        local_gem_path = File.join cache_dir, gem_file_name
+        return if File.exist? local_gem_path
+
+        begin
+          remote_gem_path = uri + "gems/#{gem_file_name}"
+
+          SharedHelpers.filesystem_access(local_gem_path) do
+            fetcher.cache_update_path remote_gem_path, local_gem_path
+          end
+        rescue Gem::RemoteFetcher::FetchError
+          raise if spec.original_platform == spec.platform
+
+          original_gem_file_name = "#{spec.original_name}.gem"
+          raise if gem_file_name == original_gem_file_name
+
+          gem_file_name = original_gem_file_name
+          retry
+        end
+      end
+    rescue Gem::RemoteFetcher::FetchError => e
+      raise Bundler::HTTPError, "Could not download gem from #{redacted_uri} due to underlying error <#{e.message}>"
+    end
+
+    def build(spec, skip_validation = false)
+      require "rubygems/package"
+      Gem::Package.build(spec, skip_validation)
+    end
+
+    def path_separator
+      Gem.path_separator
+    end
+
+    def all_specs
+      SharedHelpers.feature_removed! "Bundler.rubygems.all_specs has been removed in favor of Bundler.rubygems.installed_specs"
+    end
+
+    def installed_specs
+      Gem::Specification.stubs.reject(&:default_gem?).map do |stub|
+        StubSpecification.from_stub(stub)
+      end
+    end
+
+    def default_specs
+      Gem::Specification.default_stubs.map do |stub|
+        StubSpecification.from_stub(stub)
+      end
+    end
+
+    def find_bundler(version)
+      find_name("bundler").find {|s| s.version.to_s == version.to_s }
+    end
+
+    def find_name(name)
+      Gem::Specification.stubs_for(name).map(&:to_spec)
+    end
+
+    def default_stubs
+      Gem::Specification.default_stubs("*.gemspec")
+    end
+
+    private
+
+    def gem_class
+      class << Gem; self; end
+    end
+  end
+
+  def self.rubygems
+    @rubygems ||= RubygemsIntegration.new
+  end
+end
diff --git a/lib/bundler/runtime.rb b/lib/bundler/runtime.rb
new file mode 100644
index 0000000000..5280e72aa2
--- /dev/null
+++ b/lib/bundler/runtime.rb
@@ -0,0 +1,331 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Runtime
+    include SharedHelpers
+
+    def initialize(root, definition)
+      @root = root
+      @definition = definition
+    end
+
+    def setup(*groups)
+      @definition.ensure_equivalent_gemfile_and_lockfile
+
+      # Has to happen first
+      clean_load_path
+
+      specs = @definition.specs_for(groups)
+
+      SharedHelpers.set_bundle_environment
+      Bundler.rubygems.replace_entrypoints(specs)
+
+      # Activate the specs
+      load_paths = specs.map do |spec|
+        check_for_activated_spec!(spec)
+
+        Bundler.rubygems.mark_loaded(spec)
+        spec.load_paths.reject {|path| $LOAD_PATH.include?(path) }
+      end.reverse.flatten
+
+      Gem.add_to_load_path(*load_paths)
+
+      setup_manpath
+
+      lock(preserve_unknown_sections: true)
+
+      self
+    end
+
+    def require(*groups)
+      groups.map!(&:to_sym)
+      groups = [:default] if groups.empty?
+
+      dependencies = @definition.dependencies.select do |dep|
+        # Select the dependency if it is in any of the requested groups, and
+        # for the current platform, and matches the gem constraints.
+        (dep.groups & groups).any? && dep.should_include?
+      end
+
+      Plugin.hook(Plugin::Events::GEM_BEFORE_REQUIRE_ALL, dependencies)
+
+      dependencies.each do |dep|
+        Plugin.hook(Plugin::Events::GEM_BEFORE_REQUIRE, dep)
+
+        # Loop through all the specified autorequires for the
+        # dependency. If there are none, use the dependency's name
+        # as the autorequire.
+        Array(dep.autorequire || dep.name).each do |file|
+          # Allow `require: true` as an alias for `require: <name>`
+          file = dep.name if file == true
+          required_file = file
+          begin
+            Kernel.require required_file
+          rescue LoadError => e
+            if dep.autorequire.nil? && e.path == required_file
+              if required_file.include?("-")
+                required_file = required_file.tr("-", "/")
+                retry
+              end
+            else
+              raise Bundler::GemRequireError.new e,
+                "There was an error while trying to load the gem '#{file}'."
+            end
+          rescue StandardError => e
+            raise Bundler::GemRequireError.new e,
+              "There was an error while trying to load the gem '#{file}'."
+          end
+        end
+
+        Plugin.hook(Plugin::Events::GEM_AFTER_REQUIRE, dep)
+      end
+
+      Plugin.hook(Plugin::Events::GEM_AFTER_REQUIRE_ALL, dependencies)
+
+      dependencies
+    end
+
+    def self.definition_method(meth)
+      define_method(meth) do
+        raise ArgumentError, "no definition when calling Runtime##{meth}" unless @definition
+        @definition.send(meth)
+      end
+    end
+    private_class_method :definition_method
+
+    definition_method :requested_specs
+    definition_method :specs
+    definition_method :dependencies
+    definition_method :current_dependencies
+    definition_method :requires
+
+    def lock(opts = {})
+      return if @definition.no_resolve_needed?
+      @definition.lock(opts[:preserve_unknown_sections])
+    end
+
+    alias_method :gems, :specs
+
+    def cache(custom_path = nil, local = false)
+      cache_path = Bundler.app_cache(custom_path)
+      SharedHelpers.filesystem_access(cache_path) do |p|
+        FileUtils.mkdir_p(p)
+      end unless File.exist?(cache_path)
+
+      Bundler.ui.info "Updating files in #{Bundler.settings.app_cache_path}"
+
+      specs_to_cache = if Bundler.settings[:cache_all_platforms]
+        @definition.resolve.materialized_for_all_platforms
+      else
+        begin
+          specs
+        rescue GemNotFound
+          if local
+            Bundler.ui.warn "Some gems seem to be missing from your #{Bundler.settings.app_cache_path} directory."
+          end
+
+          raise
+        end
+      end
+
+      specs_to_cache.each do |spec|
+        next if spec.name == "bundler"
+
+        source = spec.source
+        next if source.is_a?(Source::Gemspec)
+
+        if source.respond_to?(:migrate_cache)
+          source.migrate_cache(custom_path, local: local)
+        elsif source.respond_to?(:cache)
+          source.cache(spec, custom_path)
+        end
+      end
+
+      Dir[cache_path.join("*/.git")].each do |git_dir|
+        FileUtils.rm_rf(git_dir)
+        FileUtils.touch(File.expand_path("../.bundlecache", git_dir))
+      end
+
+      prune_cache(cache_path) unless Bundler.settings[:no_prune]
+    end
+
+    def prune_cache(cache_path)
+      SharedHelpers.filesystem_access(cache_path) do |p|
+        FileUtils.mkdir_p(p)
+      end unless File.exist?(cache_path)
+      resolve = @definition.resolve
+      prune_gem_cache(resolve, cache_path)
+      prune_git_and_path_cache(resolve, cache_path)
+    end
+
+    def clean(dry_run = false)
+      gem_bins             = Dir["#{Gem.dir}/bin/*"]
+      git_dirs             = Dir["#{Gem.dir}/bundler/gems/*"]
+      git_cache_dirs       = Dir["#{Gem.dir}/cache/bundler/git/*"]
+      gem_dirs             = Dir["#{Gem.dir}/gems/*"]
+      gem_files            = Dir["#{Gem.dir}/cache/*.gem"]
+      gemspec_files        = Dir["#{Gem.dir}/specifications/*.gemspec"]
+      extension_dirs       = Dir["#{Gem.dir}/extensions/*/*/*"] + Dir["#{Gem.dir}/bundler/gems/extensions/*/*/*"]
+      spec_gem_paths       = []
+      # need to keep git sources around
+      spec_git_paths       = @definition.spec_git_paths
+      spec_git_cache_dirs  = []
+      spec_gem_executables = []
+      spec_cache_paths     = []
+      spec_gemspec_paths   = []
+      spec_extension_paths = []
+      specs_to_keep = Bundler.rubygems.add_default_gems_to(specs).values
+
+      current_bundler = Bundler.rubygems.find_bundler(Bundler.gem_version)
+      if current_bundler
+        specs_to_keep << current_bundler
+      end
+
+      specs_to_keep.each do |spec|
+        spec_gem_paths << spec.full_gem_path
+        # need to check here in case gems are nested like for the rails git repo
+        md = %r{(.+bundler/gems/.+-[a-f0-9]{7,12})}.match(spec.full_gem_path)
+        spec_git_paths << md[1] if md
+        spec_gem_executables << spec.executables.collect do |executable|
+          e = "#{Bundler.rubygems.gem_bindir}/#{executable}"
+          [e, "#{e}.bat"]
+        end
+        spec_cache_paths << spec.cache_file
+        spec_gemspec_paths << spec.spec_file
+        spec_extension_paths << spec.extension_dir if spec.respond_to?(:extension_dir)
+        spec_git_cache_dirs << spec.source.cache_path.to_s if spec.source.is_a?(Bundler::Source::Git)
+      end
+      spec_gem_paths.uniq!
+      spec_gem_executables.flatten!
+
+      stale_gem_bins       = gem_bins - spec_gem_executables
+      stale_git_dirs       = git_dirs - spec_git_paths - ["#{Gem.dir}/bundler/gems/extensions"]
+      stale_git_cache_dirs = git_cache_dirs - spec_git_cache_dirs
+      stale_gem_dirs       = gem_dirs - spec_gem_paths
+      stale_gem_files      = gem_files - spec_cache_paths
+      stale_gemspec_files  = gemspec_files - spec_gemspec_paths
+      stale_extension_dirs = extension_dirs - spec_extension_paths
+
+      removed_stale_gem_dirs = stale_gem_dirs.collect {|dir| remove_dir(dir, dry_run) }
+      removed_stale_git_dirs = stale_git_dirs.collect {|dir| remove_dir(dir, dry_run) }
+      output = removed_stale_gem_dirs + removed_stale_git_dirs
+
+      unless dry_run
+        stale_files = stale_gem_bins + stale_gem_files + stale_gemspec_files
+        stale_files.each do |file|
+          SharedHelpers.filesystem_access(File.dirname(file)) do |_p|
+            FileUtils.rm(file) if File.exist?(file)
+          end
+        end
+
+        stale_dirs = stale_git_cache_dirs + stale_extension_dirs
+        stale_dirs.each do |stale_dir|
+          SharedHelpers.filesystem_access(stale_dir) do |dir|
+            FileUtils.rm_rf(dir) if File.exist?(dir)
+          end
+        end
+      end
+
+      output
+    end
+
+    private
+
+    def prune_gem_cache(resolve, cache_path)
+      cached = Dir["#{cache_path}/*.gem"]
+
+      cached = cached.delete_if do |path|
+        spec = Bundler.rubygems.spec_from_gem path
+
+        resolve.any? do |s|
+          s.name == spec.name && s.version == spec.version && !s.source.is_a?(Bundler::Source::Git)
+        end
+      end
+
+      if cached.any?
+        Bundler.ui.info "Removing outdated .gem files from #{Bundler.settings.app_cache_path}"
+
+        cached.each do |path|
+          Bundler.ui.info "  * #{File.basename(path)}"
+
+          begin
+            File.delete(path)
+          rescue Errno::ENOENT
+          end
+        end
+      end
+    end
+
+    def prune_git_and_path_cache(resolve, cache_path)
+      cached = Dir["#{cache_path}/*/.bundlecache"]
+
+      cached = cached.delete_if do |path|
+        name = File.basename(File.dirname(path))
+
+        resolve.any? do |s|
+          source = s.source
+          source.respond_to?(:app_cache_dirname) && source.app_cache_dirname == name
+        end
+      end
+
+      if cached.any?
+        Bundler.ui.info "Removing outdated git and path gems from #{Bundler.settings.app_cache_path}"
+
+        cached.each do |path|
+          path = File.dirname(path)
+          Bundler.ui.info "  * #{File.basename(path)}"
+          FileUtils.rm_rf(path)
+        end
+      end
+    end
+
+    def setup_manpath
+      # Add man/ subdirectories from activated bundles to MANPATH for man(1)
+      manuals = $LOAD_PATH.filter_map do |path|
+        man_subdir = path.sub(/lib$/, "man")
+        man_subdir unless Dir[man_subdir + "/man?/"].empty?
+      end
+
+      return if manuals.empty?
+      Bundler::SharedHelpers.set_env "MANPATH", manuals.concat(
+        ENV["MANPATH"] ? ENV["MANPATH"].to_s.split(File::PATH_SEPARATOR) : [""]
+      ).uniq.join(File::PATH_SEPARATOR)
+    end
+
+    def remove_dir(dir, dry_run)
+      full_name = Pathname.new(dir).basename.to_s
+
+      parts    = full_name.split("-")
+      name     = parts[0..-2].join("-")
+      version  = parts.last
+      output   = "#{name} (#{version})"
+
+      if dry_run
+        Bundler.ui.info "Would have removed #{output}"
+      else
+        Bundler.ui.info "Removing #{output}"
+        FileUtils.rm_rf(dir)
+      end
+
+      output
+    end
+
+    def check_for_activated_spec!(spec)
+      return unless activated_spec = Bundler.rubygems.loaded_specs(spec.name)
+      return if activated_spec.version == spec.version
+
+      suggestion = if activated_spec.default_gem?
+        "Since #{spec.name} is a default gem, you can either remove your dependency on it" \
+        " or try updating to a newer version of bundler that supports #{spec.name} as a default gem."
+      else
+        "Prepending `bundle exec` to your command may solve this."
+      end
+
+      e = Gem::LoadError.new "You have already activated #{activated_spec.name} #{activated_spec.version}, " \
+                             "but your Gemfile requires #{spec.name} #{spec.version}. #{suggestion}"
+      e.name = spec.name
+      e.requirement = Gem::Requirement.new(spec.version.to_s)
+      raise e
+    end
+  end
+end
diff --git a/lib/bundler/safe_marshal.rb b/lib/bundler/safe_marshal.rb
new file mode 100644
index 0000000000..50aa0f60a6
--- /dev/null
+++ b/lib/bundler/safe_marshal.rb
@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+module Bundler
+  module SafeMarshal
+    ALLOWED_CLASSES = [
+      Array,
+      FalseClass,
+      Gem::Specification,
+      Gem::Version,
+      Hash,
+      String,
+      Symbol,
+      Time,
+      TrueClass,
+    ].freeze
+
+    ERROR = "Unexpected class %s present in marshaled data. Only %s are allowed."
+
+    PROC = proc do |object|
+      object.tap do
+        unless ALLOWED_CLASSES.include?(object.class)
+          raise TypeError, format(ERROR, object.class, ALLOWED_CLASSES.join(", "))
+        end
+      end
+    end
+
+    def self.proc
+      PROC
+    end
+  end
+end
diff --git a/lib/bundler/self_manager.rb b/lib/bundler/self_manager.rb
new file mode 100644
index 0000000000..82efbf56a4
--- /dev/null
+++ b/lib/bundler/self_manager.rb
@@ -0,0 +1,197 @@
+# frozen_string_literal: true
+
+module Bundler
+  #
+  # This class handles installing and switching to the version of bundler needed
+  # by an application.
+  #
+  class SelfManager
+    def restart_with_locked_bundler_if_needed
+      restart_version = find_restart_version
+      return unless restart_version && installed?(restart_version)
+
+      restart_with(restart_version)
+    end
+
+    def install_locked_bundler_and_restart_with_it_if_needed
+      restart_version = find_restart_version
+      return unless restart_version
+
+      if restart_version == lockfile_version
+        Bundler.ui.info \
+          "Bundler #{current_version} is running, but your lockfile was generated with #{lockfile_version}. " \
+          "Installing Bundler #{lockfile_version} and restarting using that version."
+      else
+        Bundler.ui.info \
+          "Bundler #{current_version} is running, but your configuration was #{restart_version}. " \
+          "Installing Bundler #{restart_version} and restarting using that version."
+      end
+
+      install_and_restart_with(restart_version)
+    end
+
+    def update_bundler_and_restart_with_it_if_needed(target)
+      spec = resolve_update_version_from(target)
+      return unless spec
+
+      version = spec.version
+
+      Bundler.ui.info "Updating bundler to #{version}."
+
+      install(spec) unless installed?(version)
+
+      restart_with(version)
+    end
+
+    private
+
+    def install_and_restart_with(version)
+      requirement = Gem::Requirement.new(version)
+      spec = find_latest_matching_spec(requirement)
+
+      if spec.nil?
+        Bundler.ui.warn "Your lockfile is locked to a version of bundler (#{lockfile_version}) that doesn't exist at https://rubygems.org/. Going on using #{current_version}"
+        return
+      end
+
+      install(spec)
+    rescue StandardError => e
+      Bundler.ui.trace e
+      Bundler.ui.warn "There was an error installing the locked bundler version (#{lockfile_version}), rerun with the `--verbose` flag for more details. Going on using bundler #{current_version}."
+    else
+      restart_with(version)
+    end
+
+    def install(spec)
+      spec.source.download(spec)
+      spec.source.install(spec)
+    end
+
+    def restart_with(version)
+      configured_gem_home = ENV["GEM_HOME"]
+      configured_orig_gem_home = ENV["BUNDLER_ORIG_GEM_HOME"]
+      configured_gem_path = ENV["GEM_PATH"]
+      configured_orig_gem_path = ENV["BUNDLER_ORIG_GEM_PATH"]
+
+      argv0 = File.exist?($PROGRAM_NAME) ? $PROGRAM_NAME : Process.argv0
+      cmd = [argv0, *ARGV]
+      cmd.unshift(Gem.ruby) unless File.executable?(argv0)
+
+      Bundler.with_original_env do
+        Kernel.exec(
+          {
+            "GEM_HOME" => configured_gem_home,
+            "BUNDLER_ORIG_GEM_HOME" => configured_orig_gem_home,
+            "GEM_PATH" => configured_gem_path,
+            "BUNDLER_ORIG_GEM_PATH" => configured_orig_gem_path,
+            "BUNDLER_VERSION" => version.to_s,
+          },
+          *cmd
+        )
+      end
+    end
+
+    def needs_switching?(restart_version)
+      autoswitching_applies? &&
+        released?(restart_version) &&
+        !running?(restart_version)
+    end
+
+    def autoswitching_applies?
+      (ENV["BUNDLER_VERSION"].nil? || ENV["BUNDLER_VERSION"].empty?) &&
+        ruby_can_restart_with_same_arguments? &&
+        lockfile_version
+    end
+
+    def resolve_update_version_from(target)
+      requirement = Gem::Requirement.new(target)
+      update_candidate = find_latest_matching_spec(requirement)
+
+      if update_candidate.nil?
+        raise InvalidOption, "The `bundle update --bundler` target version (#{target}) does not exist"
+      end
+
+      resolved_version = update_candidate.version
+      needs_update = requirement.specific? ? !running?(resolved_version) : running_older_than?(resolved_version)
+
+      return unless needs_update
+
+      update_candidate
+    end
+
+    def local_specs
+      @local_specs ||= Bundler::Source::Rubygems.new("allow_local" => true).specs.select {|spec| spec.name == "bundler" }
+    end
+
+    def remote_specs
+      @remote_specs ||= begin
+        source = Bundler::Source::Rubygems.new("remotes" => "https://rubygems.org")
+        source.remote!
+        source.add_dependency_names("bundler")
+        source.specs.select(&:matches_current_metadata?)
+      end
+    end
+
+    def find_latest_matching_spec(requirement)
+      Bundler.configure
+      local_result = find_latest_matching_spec_from_collection(local_specs, requirement)
+      return local_result if local_result && requirement.specific?
+
+      remote_result = find_latest_matching_spec_from_collection(remote_specs, requirement)
+      return remote_result if local_result.nil?
+
+      [local_result, remote_result].max
+    end
+
+    def find_latest_matching_spec_from_collection(specs, requirement)
+      specs.sort.reverse_each.find {|spec| requirement.satisfied_by?(spec.version) }
+    end
+
+    def running?(version)
+      version == current_version
+    end
+
+    def running_older_than?(version)
+      current_version < version
+    end
+
+    def released?(version)
+      !version.to_s.end_with?(".dev")
+    end
+
+    def ruby_can_restart_with_same_arguments?
+      $PROGRAM_NAME != "-e"
+    end
+
+    def installed?(restart_version)
+      Bundler.configure
+
+      Bundler.rubygems.find_bundler(restart_version.to_s)
+    end
+
+    def current_version
+      @current_version ||= Bundler.gem_version
+    end
+
+    def lockfile_version
+      return @lockfile_version if defined?(@lockfile_version)
+
+      parsed_version = Bundler::LockfileParser.bundled_with
+      @lockfile_version = parsed_version ? Gem::Version.new(parsed_version) : nil
+    rescue ArgumentError
+      @lockfile_version = nil
+    end
+
+    def find_restart_version
+      return unless SharedHelpers.in_bundle?
+
+      configured_version = Bundler.settings[:version]
+      return if configured_version == "system"
+
+      restart_version = configured_version == "lockfile" ? lockfile_version : Gem::Version.new(configured_version)
+      return unless needs_switching?(restart_version)
+
+      restart_version
+    end
+  end
+end
diff --git a/lib/bundler/settings.rb b/lib/bundler/settings.rb
new file mode 100644
index 0000000000..fd77c2f7fc
--- /dev/null
+++ b/lib/bundler/settings.rb
@@ -0,0 +1,587 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Settings
+    autoload :Mirror,  File.expand_path("mirror", __dir__)
+    autoload :Mirrors, File.expand_path("mirror", __dir__)
+    autoload :Validator, File.expand_path("settings/validator", __dir__)
+
+    BOOL_KEYS = %w[
+      auto_install
+      cache_all
+      cache_all_platforms
+      clean
+      deployment
+      disable_checksum_validation
+      disable_exec_load
+      disable_local_branch_check
+      disable_local_revision_check
+      disable_shared_gems
+      disable_version_check
+      force_ruby_platform
+      frozen
+      gem.changelog
+      gem.coc
+      gem.mit
+      gem.bundle
+      git.allow_insecure
+      global_gem_cache
+      ignore_messages
+      init_gems_rb
+      inline
+      lockfile_checksums
+      no_build_extension
+      no_install
+      no_install_plugin
+      no_prune
+      path.system
+      plugins
+      prefer_patch
+      silence_deprecations
+      silence_root_warning
+      update_requires_all_flag
+      verbose
+    ].freeze
+
+    NUMBER_KEYS = %w[
+      cooldown
+      jobs
+      redirect
+      retry
+      ssl_verify_mode
+      timeout
+    ].freeze
+
+    ARRAY_KEYS = %w[
+      only
+      with
+      without
+    ].freeze
+
+    STRING_KEYS = %w[
+      bin
+      cache_path
+      console
+      default_cli_command
+      gem.ci
+      gem.github_username
+      gem.linter
+      gem.rubocop
+      gem.test
+      gemfile
+      lockfile
+      path
+      shebang
+      simulate_version
+      system_bindir
+      trust-policy
+      version
+    ].freeze
+
+    DEFAULT_CONFIG = {
+      "BUNDLE_SILENCE_DEPRECATIONS" => false,
+      "BUNDLE_DISABLE_VERSION_CHECK" => true,
+      "BUNDLE_PREFER_PATCH" => false,
+      "BUNDLE_REDIRECT" => 5,
+      "BUNDLE_RETRY" => 3,
+      "BUNDLE_TIMEOUT" => 10,
+      "BUNDLE_VERSION" => "lockfile",
+      "BUNDLE_LOCKFILE_CHECKSUMS" => true,
+      "BUNDLE_CACHE_ALL" => true,
+      "BUNDLE_PLUGINS" => true,
+      "BUNDLE_GLOBAL_GEM_CACHE" => false,
+      "BUNDLE_UPDATE_REQUIRES_ALL_FLAG" => false,
+    }.freeze
+
+    def initialize(root = nil)
+      @root            = root
+      @local_config    = load_config(local_config_file)
+      @local_root      = root || Pathname.new(".bundle").expand_path
+
+      @env_config      = ENV.to_h
+      @env_config.select! {|key, _value| key.start_with?("BUNDLE_") }
+      @env_config.delete("BUNDLE_")
+
+      @global_config   = load_config(global_config_file)
+      @temporary       = {}
+
+      @key_cache = {}
+    end
+
+    def [](name)
+      key = key_for(name)
+
+      value = nil
+      configs.each do |_, config|
+        value = config[key]
+        next if value.nil?
+        break
+      end
+
+      converted_value(value, name)
+    end
+
+    def set_command_option(key, value)
+      temporary(key => value)
+      value
+    end
+
+    def set_command_option_if_given(key, value)
+      return if value.nil?
+      set_command_option(key, value)
+    end
+
+    def set_local(key, value)
+      local_config_file = @local_root.join("config")
+
+      set_key(key, value, @local_config, local_config_file)
+    end
+
+    def temporary(update)
+      existing = Hash[update.map {|k, _| [k, @temporary[key_for(k)]] }]
+      update.each do |k, v|
+        set_key(k, v, @temporary, nil)
+      end
+      return unless block_given?
+      begin
+        yield
+      ensure
+        existing.each {|k, v| set_key(k, v, @temporary, nil) }
+      end
+    end
+
+    def set_global(key, value)
+      set_key(key, value, @global_config, global_config_file)
+    end
+
+    def all
+      keys = @temporary.keys.union(@global_config.keys, @local_config.keys, @env_config.keys)
+
+      keys.map! do |key|
+        key = key.delete_prefix("BUNDLE_")
+        key.gsub!("___", "-")
+        key.gsub!("__", ".")
+        key.downcase!
+        key
+      end.sort!
+      keys
+    end
+
+    def local_overrides
+      repos = {}
+      all.each do |k|
+        repos[k.delete_prefix("local.")] = self[k] if k.start_with?("local.")
+      end
+      repos
+    end
+
+    def mirror_for(uri)
+      if uri.is_a?(String)
+        require_relative "vendored_uri"
+        uri = Gem::URI(uri)
+      end
+
+      gem_mirrors.for(uri.to_s).uri
+    end
+
+    def credentials_for(uri)
+      self[uri.to_s] || self[uri.host]
+    end
+
+    def gem_mirrors
+      all.inject(Mirrors.new) do |mirrors, k|
+        mirrors.parse(k, self[k]) if k.start_with?("mirror.")
+        mirrors
+      end
+    end
+
+    def locations(key)
+      key = key_for(key)
+      configs.keys.inject({}) do |partial_locations, level|
+        value_on_level = configs[level][key]
+        partial_locations[level] = value_on_level unless value_on_level.nil?
+        partial_locations
+      end
+    end
+
+    def pretty_values_for(exposed_key)
+      key = key_for(exposed_key)
+
+      locations = []
+
+      if value = @temporary[key]
+        locations << "Set for the current command: #{printable_value(value, exposed_key).inspect}"
+      end
+
+      if value = @local_config[key]
+        locations << "Set for your local app (#{local_config_file}): #{printable_value(value, exposed_key).inspect}"
+      end
+
+      if value = @env_config[key]
+        locations << "Set via #{key}: #{printable_value(value, exposed_key).inspect}"
+      end
+
+      if value = @global_config[key]
+        locations << "Set for the current user (#{global_config_file}): #{printable_value(value, exposed_key).inspect}"
+      end
+
+      return ["You have not configured a value for `#{exposed_key}`"] if locations.empty?
+      locations
+    end
+
+    def processor_count
+      require "etc"
+      Etc.nprocessors
+    rescue StandardError
+      1
+    end
+
+    # for legacy reasons, in Bundler 2, we do not respect :disable_shared_gems
+    def path
+      configs.each do |_level, settings|
+        path = value_for("path", settings)
+        path_system = value_for("path.system", settings)
+        disabled_shared_gems = value_for("disable_shared_gems", settings)
+        next if path.nil? && path_system.nil? && disabled_shared_gems.nil?
+        system_path = path_system || (disabled_shared_gems == false)
+        return Path.new(path, system_path)
+      end
+
+      path = "vendor/bundle" if self[:deployment]
+
+      Path.new(path, false)
+    end
+
+    Path = Struct.new(:explicit_path, :system_path) do
+      def path
+        path = base_path
+        path = File.join(path, Bundler.ruby_scope) unless use_system_gems?
+        path
+      end
+
+      def use_system_gems?
+        return true if system_path
+        return false if explicit_path
+        !Bundler.feature_flag.bundler_5_mode?
+      end
+
+      def base_path
+        path = explicit_path
+        path ||= ".bundle" unless use_system_gems?
+        path ||= Bundler.rubygems.gem_dir
+        path
+      end
+
+      def base_path_relative_to_pwd
+        base_path = Pathname.new(self.base_path)
+        expanded_base_path = base_path.expand_path(Bundler.root)
+        relative_path = expanded_base_path.relative_path_from(Pathname.pwd)
+        if relative_path.to_s.start_with?("..")
+          relative_path = base_path if base_path.absolute?
+        else
+          relative_path = Pathname.new(File.join(".", relative_path))
+        end
+        relative_path
+      rescue ArgumentError
+        expanded_base_path
+      end
+
+      def validate!
+        return unless explicit_path && system_path
+        path = Bundler.settings.pretty_values_for(:path)
+        path.unshift(nil, "path:") unless path.empty?
+        system_path = Bundler.settings.pretty_values_for("path.system")
+        system_path.unshift(nil, "path.system:") unless system_path.empty?
+        disable_shared_gems = Bundler.settings.pretty_values_for(:disable_shared_gems)
+        disable_shared_gems.unshift(nil, "disable_shared_gems:") unless disable_shared_gems.empty?
+        raise InvalidOption,
+          "Using a custom path while using system gems is unsupported.\n#{path.join("\n")}\n#{system_path.join("\n")}\n#{disable_shared_gems.join("\n")}"
+      end
+    end
+
+    def ignore_config?
+      ENV["BUNDLE_IGNORE_CONFIG"]
+    end
+
+    def app_cache_path
+      @app_cache_path ||= self[:cache_path] || "vendor/cache"
+    end
+
+    def installation_parallelization
+      self[:jobs] || processor_count
+    end
+
+    def validate!
+      all.each do |raw_key|
+        [@local_config, @env_config, @global_config].each do |settings|
+          value = value_for(raw_key, settings)
+          Validator.validate!(raw_key, value, settings.dup)
+        end
+      end
+    end
+
+    def key_for(key)
+      @key_cache[key] ||= self.class.key_for(key)
+    end
+
+    private
+
+    def configs
+      @configs ||= {
+        temporary: @temporary,
+        local: @local_config,
+        env: @env_config,
+        global: @global_config,
+        default: DEFAULT_CONFIG,
+      }
+    end
+
+    def value_for(name, config)
+      converted_value(config[key_for(name)], name)
+    end
+
+    def parent_setting_for(name)
+      split_specific_setting_for(name)[0]
+    end
+
+    def specific_gem_for(name)
+      split_specific_setting_for(name)[1]
+    end
+
+    def split_specific_setting_for(name)
+      name.split(".")
+    end
+
+    def is_bool(name)
+      name = self.class.key_to_s(name)
+      BOOL_KEYS.include?(name) || BOOL_KEYS.include?(parent_setting_for(name))
+    end
+
+    def is_string(name)
+      name = self.class.key_to_s(name)
+      STRING_KEYS.include?(name) || name.start_with?("local.") || name.start_with?("mirror.") || name.start_with?("build.")
+    end
+
+    def to_bool(value)
+      case value
+      when String
+        value.match?(/\A(false|f|no|n|0|)\z/i) ? false : true
+      when nil, false
+        false
+      else
+        true
+      end
+    end
+
+    def is_num(key)
+      NUMBER_KEYS.include?(self.class.key_to_s(key))
+    end
+
+    def is_array(key)
+      ARRAY_KEYS.include?(self.class.key_to_s(key))
+    end
+
+    def is_credential(key)
+      key == "gem.push_key"
+    end
+
+    def is_userinfo(value)
+      value.include?(":")
+    end
+
+    def to_array(value)
+      return [] unless value
+      value.tr(" ", ":").split(":").map(&:to_sym)
+    end
+
+    def array_to_s(array)
+      array = Array(array)
+      return nil if array.empty?
+      array.join(":").tr(" ", ":")
+    end
+
+    def set_key(raw_key, value, hash, file)
+      raw_key = self.class.key_to_s(raw_key)
+      value = array_to_s(value) if is_array(raw_key)
+
+      key = key_for(raw_key)
+
+      return if hash[key] == value
+
+      hash[key] = value
+      hash.delete(key) if value.nil?
+
+      Validator.validate!(raw_key, converted_value(value, raw_key), hash)
+
+      return unless file
+
+      SharedHelpers.filesystem_access(file.dirname, :create) do |p|
+        FileUtils.mkdir_p(p)
+      end
+
+      SharedHelpers.filesystem_access(file) do |p|
+        p.open("w") {|f| f.write(serializer_class.dump(hash)) }
+      end
+    end
+
+    def converted_value(value, key)
+      key = self.class.key_to_s(key)
+
+      if is_array(key)
+        to_array(value)
+      elsif value.nil?
+        nil
+      elsif is_bool(key) || value == "false"
+        to_bool(value)
+      elsif is_num(key)
+        value.to_i
+      else
+        value.to_s
+      end
+    end
+
+    def printable_value(value, key)
+      converted = converted_value(value, key)
+      return converted unless converted.is_a?(String)
+
+      if is_string(key)
+        converted
+      elsif is_credential(key)
+        "[REDACTED]"
+      elsif is_userinfo(converted)
+        username, pass = converted.split(":", 2)
+
+        if pass == "x-oauth-basic"
+          username = "[REDACTED]"
+        else
+          pass = "[REDACTED]"
+        end
+
+        [username, pass].join(":")
+      else
+        converted
+      end
+    end
+
+    def global_config_file
+      if ENV["BUNDLE_CONFIG"] && !ENV["BUNDLE_CONFIG"].empty?
+        Pathname.new(ENV["BUNDLE_CONFIG"])
+      elsif ENV["BUNDLE_USER_CONFIG"] && !ENV["BUNDLE_USER_CONFIG"].empty?
+        Pathname.new(ENV["BUNDLE_USER_CONFIG"])
+      elsif ENV["BUNDLE_USER_HOME"] && !ENV["BUNDLE_USER_HOME"].empty?
+        Pathname.new(ENV["BUNDLE_USER_HOME"]).join("config")
+      elsif Bundler.rubygems.user_home && !Bundler.rubygems.user_home.empty?
+        Pathname.new(Bundler.rubygems.user_home).join(".bundle/config")
+      end
+    end
+
+    def local_config_file
+      Pathname.new(@root).join("config") if @root
+    end
+
+    def load_config(config_file)
+      return {} if !config_file || ignore_config?
+      SharedHelpers.filesystem_access(config_file, :read) do |file|
+        valid_file = file.exist? && !file.size.zero?
+        return {} unless valid_file
+        (serializer_class.load(file.read) || {}).inject({}) do |config, (k, v)|
+          k = k.dup
+          k << "/" if /https?:/i.match?(k) && !k.end_with?("/", "__#{FALLBACK_TIMEOUT_URI_OPTION.upcase}")
+          k.gsub!(".", "__")
+
+          unless k.start_with?("#")
+            if k.include?("-")
+              Bundler.ui.warn "Your #{file} config includes `#{k}`, which contains the dash character (`-`).\n" \
+                "This is deprecated, because configuration through `ENV` should be possible, but `ENV` keys cannot include dashes.\n" \
+                "Please edit #{file} and replace any dashes in configuration keys with a triple underscore (`___`)."
+
+              # string hash keys are frozen
+              k = k.gsub("-", "___")
+            end
+
+            config[k] = v
+          end
+
+          config
+        end
+      end
+    end
+
+    def serializer_class
+      require "rubygems/yaml_serializer"
+      Gem::YAMLSerializer
+    rescue LoadError
+      # TODO: Remove this when RubyGems 3.4 is EOL
+      require_relative "yaml_serializer"
+      YAMLSerializer
+    end
+
+    FALLBACK_TIMEOUT_URI_OPTION = "fallback_timeout"
+
+    NORMALIZE_URI_OPTIONS_PATTERN =
+      /
+        \A
+        (\w+\.)? # optional prefix key
+        (https?.*?) # URI
+        (\.#{FALLBACK_TIMEOUT_URI_OPTION})? # optional suffix key
+        \z
+      /ix
+
+    def self.key_for(key)
+      key = key_to_s(key)
+      key = normalize_uri(key) if key.start_with?("http", "mirror.http")
+      key = key.gsub(".", "__")
+      key.gsub!("-", "___")
+      key.upcase!
+
+      key.gsub(/\A([ #]*)/, '\1BUNDLE_')
+    end
+
+    # TODO: duplicates Rubygems#normalize_uri
+    # TODO: is this the correct place to validate mirror URIs?
+    def self.normalize_uri(uri)
+      uri = uri.to_s
+      if uri =~ NORMALIZE_URI_OPTIONS_PATTERN
+        prefix = $1
+        uri = $2
+        suffix = $3
+      end
+      uri = URINormalizer.normalize_suffix(uri)
+      require_relative "vendored_uri"
+      uri = Gem::URI(uri)
+      unless uri.absolute?
+        raise ArgumentError, format("Gem sources must be absolute. You provided '%s'.", uri)
+      end
+      "#{prefix}#{uri}#{suffix}"
+    end
+
+    # This is a hot method, so avoid respond_to? checks on every invocation
+    if :read.respond_to?(:name)
+      def self.key_to_s(key)
+        case key
+        when String
+          key
+        when Symbol
+          key.name
+        when Gem::URI::HTTP
+          key.to_s
+        else
+          raise ArgumentError, "Invalid key: #{key.inspect}"
+        end
+      end
+    else
+      def self.key_to_s(key)
+        case key
+        when String
+          key
+        when Symbol
+          key.to_s
+        when Gem::URI::HTTP
+          key.to_s
+        else
+          raise ArgumentError, "Invalid key: #{key.inspect}"
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/settings/validator.rb b/lib/bundler/settings/validator.rb
new file mode 100644
index 0000000000..70a0ca36d4
--- /dev/null
+++ b/lib/bundler/settings/validator.rb
@@ -0,0 +1,86 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Settings
+    class Validator
+      class Rule
+        attr_reader :description
+
+        def initialize(keys, description, &validate)
+          @keys = keys
+          @description = description
+          @validate = validate
+        end
+
+        def validate!(key, value, settings)
+          instance_exec(key, value, settings, &@validate)
+        end
+
+        def fail!(key, value, *reasons)
+          reasons.unshift @description
+          raise InvalidOption, "Setting `#{key}` to #{value.inspect} failed:\n#{reasons.map {|r| " - #{r}" }.join("\n")}"
+        end
+
+        def set(settings, key, value, *reasons)
+          hash_key = k(key)
+          return if settings[hash_key] == value
+          reasons.unshift @description
+          Bundler.ui.info "Setting `#{key}` to #{value.inspect}, since #{reasons.join(", ")}"
+          if value.nil?
+            settings.delete(hash_key)
+          else
+            settings[hash_key] = value
+          end
+        end
+
+        def k(key)
+          Bundler.settings.key_for(key)
+        end
+      end
+
+      def self.rules
+        @rules ||= Hash.new {|h, k| h[k] = [] }
+      end
+      private_class_method :rules
+
+      def self.rule(keys, description, &blk)
+        rule = Rule.new(keys, description, &blk)
+        keys.each {|k| rules[k] << rule }
+      end
+      private_class_method :rule
+
+      def self.validate!(key, value, settings)
+        rules_to_validate = rules[key]
+        rules_to_validate.each {|rule| rule.validate!(key, value, settings) }
+      end
+
+      rule %w[path path.system], "path and path.system are mutually exclusive" do |key, value, settings|
+        if key == "path" && value
+          set(settings, "path.system", nil)
+        elsif key == "path.system" && value
+          set(settings, :path, nil)
+        end
+      end
+
+      rule %w[with without], "a group cannot be in both `with` & `without` simultaneously" do |key, value, settings|
+        with = settings.fetch(k(:with), "").split(":").map(&:to_sym)
+        without = settings.fetch(k(:without), "").split(":").map(&:to_sym)
+
+        other_key = key == "with" ? :without : :with
+        other_setting = key == "with" ? without : with
+
+        conflicting = with & without
+        if conflicting.any?
+          fail!(key, value, "`#{other_key}` is current set to #{other_setting.inspect}", "the `#{conflicting.join("`, `")}` groups conflict")
+        end
+      end
+
+      rule %w[default_cli_command], "default_cli_command must be either 'install' or 'cli_help'" do |key, value, _settings|
+        valid_values = %w[install cli_help]
+        if !value.nil? && !valid_values.include?(value.to_s)
+          fail!(key, value, "must be one of: #{valid_values.join(", ")}")
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/setup.rb b/lib/bundler/setup.rb
new file mode 100644
index 0000000000..5a0fd8e0e3
--- /dev/null
+++ b/lib/bundler/setup.rb
@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+require_relative "shared_helpers"
+
+if Bundler::SharedHelpers.in_bundle?
+  require_relative "../bundler"
+
+  # autoswitch to locked Bundler version if available
+  Bundler.auto_switch
+
+  # try to auto_install first before we get to the `Bundler.ui.silence`, so user knows what is happening
+  Bundler.auto_install
+
+  if STDOUT.tty? || ENV["BUNDLER_FORCE_TTY"]
+    begin
+      Bundler.ui.silence { Bundler.setup }
+    rescue Bundler::BundlerError => e
+      Bundler.ui.error e.message
+      Bundler.ui.warn e.backtrace.join("\n") if ENV["DEBUG"]
+      if e.is_a?(Bundler::GemNotFound)
+        default_bundle = Gem.bin_path("bundler", "bundle")
+        current_bundle = Bundler::SharedHelpers.bundle_bin_path
+        suggested_bundle = default_bundle == current_bundle ? "bundle" : current_bundle
+        suggested_cmd = "#{suggested_bundle} install"
+        original_gemfile = Bundler.original_env["BUNDLE_GEMFILE"]
+        suggested_cmd += " --gemfile #{original_gemfile}" if original_gemfile
+        Bundler.ui.warn "Run `#{suggested_cmd}` to install missing gems."
+      end
+      exit e.status_code
+    end
+  else
+    Bundler.ui.silence { Bundler.setup }
+  end
+
+  # We might be in the middle of shelling out to rubygems
+  # (RUBYOPT=-rbundler/setup), so we need to give rubygems the opportunity of
+  # not being silent.
+  Gem::DefaultUserInteraction.ui = nil
+end
diff --git a/lib/bundler/shared_helpers.rb b/lib/bundler/shared_helpers.rb
new file mode 100644
index 0000000000..2aa8abe0a0
--- /dev/null
+++ b/lib/bundler/shared_helpers.rb
@@ -0,0 +1,393 @@
+# frozen_string_literal: true
+
+require_relative "version"
+require_relative "rubygems_integration"
+require_relative "current_ruby"
+
+module Bundler
+  autoload :WINDOWS, File.expand_path("constants", __dir__)
+  autoload :FREEBSD, File.expand_path("constants", __dir__)
+  autoload :NULL, File.expand_path("constants", __dir__)
+
+  module SharedHelpers
+    def root
+      gemfile = find_gemfile
+      raise GemfileNotFound, "Could not locate Gemfile" unless gemfile
+      Pathname.new(gemfile).expand_path.parent
+    end
+
+    def default_gemfile
+      gemfile = find_gemfile
+      raise GemfileNotFound, "Could not locate Gemfile" unless gemfile
+      Pathname.new(gemfile).expand_path
+    end
+
+    def default_lockfile
+      given = ENV["BUNDLE_LOCKFILE"]
+      return Pathname.new(given) if given && !given.empty?
+
+      gemfile = default_gemfile
+
+      case gemfile.basename.to_s
+      when "gems.rb" then Pathname.new(gemfile.sub(/.rb$/, ".locked"))
+      else Pathname.new("#{gemfile}.lock")
+      end
+    end
+
+    def default_bundle_dir
+      bundle_dir = find_directory(".bundle")
+      return nil unless bundle_dir
+
+      bundle_dir = Pathname.new(bundle_dir)
+
+      global_bundle_dir = Bundler.user_home.join(".bundle")
+      return nil if bundle_dir == global_bundle_dir
+
+      bundle_dir
+    end
+
+    def in_bundle?
+      find_gemfile
+    end
+
+    def chdir(dir, &blk)
+      Bundler.rubygems.ext_lock.synchronize do
+        Dir.chdir dir, &blk
+      end
+    end
+
+    def pwd
+      Bundler.rubygems.ext_lock.synchronize do
+        Dir.pwd
+      end
+    end
+
+    def with_clean_git_env(&block)
+      keys    = %w[GIT_DIR GIT_WORK_TREE]
+      old_env = keys.inject({}) do |h, k|
+        h.update(k => ENV[k])
+      end
+
+      keys.each {|key| ENV.delete(key) }
+
+      block.call
+    ensure
+      keys.each {|key| ENV[key] = old_env[key] }
+    end
+
+    def set_bundle_environment
+      set_bundle_variables
+      set_path
+      set_rubyopt
+      set_rubylib
+    end
+
+    # Rescues permissions errors raised by file system operations
+    # (ie. Errno:EACCESS, Errno::EAGAIN) and raises more friendly errors instead.
+    #
+    # @param path [String] the path that the action will be attempted to
+    # @param action [Symbol, #to_s] the type of operation that will be
+    #   performed. For example: :write, :read, :exec
+    #
+    # @yield path
+    #
+    # @raise [Bundler::PermissionError] if Errno:EACCES is raised in the
+    #   given block
+    # @raise [Bundler::TemporaryResourceError] if Errno:EAGAIN is raised in the
+    #   given block
+    #
+    # @example
+    #   filesystem_access("vendor/cache", :create) do
+    #     FileUtils.mkdir_p("vendor/cache")
+    #   end
+    #
+    # @see {Bundler::PermissionError}
+    def filesystem_access(path, action = :write, &block)
+      yield(path.dup)
+    rescue Errno::EACCES => e
+      path_basename = File.basename(path.to_s)
+      raise unless e.message.include?(path_basename) || action == :create
+
+      raise PermissionError.new(path, action)
+    rescue Errno::EAGAIN
+      raise TemporaryResourceError.new(path, action)
+    rescue Errno::EPROTO
+      raise VirtualProtocolError.new
+    rescue Errno::ENOSPC
+      raise NoSpaceOnDeviceError.new(path, action)
+    rescue Errno::ENOTSUP
+      raise OperationNotSupportedError.new(path, action)
+    rescue Errno::EPERM
+      raise OperationNotPermittedError.new(path, action)
+    rescue Errno::EROFS
+      raise ReadOnlyFileSystemError.new(path, action)
+    rescue Errno::EEXIST, Errno::ENOENT
+      raise
+    rescue SystemCallError => e
+      raise GenericSystemCallError.new(e, "There was an error #{[:create, :write].include?(action) ? "creating" : "accessing"} `#{path}`.")
+    end
+
+    def feature_deprecated!(message)
+      return unless prints_major_deprecations?
+
+      Bundler.ui.warn("[DEPRECATED] #{message}")
+    end
+
+    def feature_removed!(message)
+      require_relative "errors"
+      raise RemovedError, "[REMOVED] #{message}"
+    end
+
+    def print_major_deprecations!
+      multiple_gemfiles = search_up(".") do |dir|
+        gemfiles = gemfile_names.select {|gf| File.file? File.expand_path(gf, dir) }
+        next if gemfiles.empty?
+        break gemfiles.size != 1
+      end
+      return unless multiple_gemfiles
+      message = "Multiple gemfiles (gems.rb and Gemfile) detected. " \
+                "Make sure you remove Gemfile and Gemfile.lock since bundler is ignoring them in favor of gems.rb and gems.locked."
+      Bundler.ui.warn message
+    end
+
+    def ensure_same_dependencies(spec, old_deps, new_deps)
+      new_deps = new_deps.reject {|d| d.type == :development }
+      old_deps = old_deps.reject {|d| d.type == :development }
+
+      without_type = proc {|d| Gem::Dependency.new(d.name, d.requirements_list.sort) }
+      new_deps.map!(&without_type)
+      old_deps.map!(&without_type)
+
+      extra_deps = new_deps - old_deps
+      return if extra_deps.empty?
+
+      Bundler.ui.debug "#{spec.full_name} from #{spec.remote} has corrupted API dependencies" \
+        " (was expecting #{old_deps.map(&:to_s)}, but the real spec has #{new_deps.map(&:to_s)})"
+      raise APIResponseMismatchError,
+        "Downloading #{spec.full_name} revealed dependencies not in the API (#{extra_deps.join(", ")})." \
+        "\nRunning `bundle update #{spec.name}` should fix the problem."
+    end
+
+    def pretty_dependency(dep)
+      msg = String.new(dep.name)
+      msg << " (#{dep.requirement})" unless dep.requirement == Gem::Requirement.default
+
+      if dep.is_a?(Bundler::Dependency)
+        platform_string = dep.platforms.join(", ")
+        msg << " " << platform_string if !platform_string.empty? && platform_string != Gem::Platform::RUBY
+      end
+
+      msg
+    end
+
+    def md5_available?
+      return @md5_available if defined?(@md5_available)
+      @md5_available = begin
+        require "openssl"
+        ::OpenSSL::Digest.digest("MD5", "")
+        true
+      rescue LoadError
+        true
+      rescue ::OpenSSL::Digest::DigestError
+        false
+      end
+    end
+
+    def digest(name)
+      require "digest"
+      Digest(name)
+    end
+
+    def checksum_for_file(path, digest)
+      return unless path.file?
+      # This must use File.read instead of Digest.file().hexdigest
+      # because we need to preserve \n line endings on windows when calculating
+      # the checksum
+      SharedHelpers.filesystem_access(path, :read) do
+        File.open(path, "rb") do |f|
+          digest = SharedHelpers.digest(digest).new
+          buf = String.new(capacity: 16_384, encoding: Encoding::BINARY)
+          digest << buf while f.read(16_384, buf)
+          digest.hexdigest
+        end
+      end
+    end
+
+    def write_to_gemfile(gemfile_path, contents)
+      filesystem_access(gemfile_path) {|g| File.open(g, "w") {|file| file.puts contents } }
+    end
+
+    def relative_gemfile_path
+      relative_path_to(Bundler.default_gemfile)
+    end
+
+    def relative_lockfile_path
+      relative_path_to(Bundler.default_lockfile)
+    end
+
+    def relative_path_to(destination, from: pwd)
+      Pathname.new(destination).relative_path_from(from).to_s
+    rescue ArgumentError
+      # on Windows, if source and destination are on different drivers, there's no relative path from one to the other
+      destination
+    end
+
+    private
+
+    def validate_bundle_path
+      path_separator = Bundler.rubygems.path_separator
+      return unless Bundler.bundle_path.to_s.split(path_separator).size > 1
+      message = "Your bundle path contains text matching #{path_separator.inspect}, " \
+                "which is the path separator for your system. Bundler cannot " \
+                "function correctly when the Bundle path contains the " \
+                "system's PATH separator. Please change your " \
+                "bundle path to not match #{path_separator.inspect}." \
+                "\nYour current bundle path is '#{Bundler.bundle_path}'."
+      raise Bundler::PathError, message
+    end
+
+    def find_gemfile
+      given = ENV["BUNDLE_GEMFILE"]
+      return given if given && !given.empty?
+      find_file(*gemfile_names)
+    end
+
+    def gemfile_names
+      ["gems.rb", "Gemfile"]
+    end
+
+    def find_file(*names)
+      search_up(*names) do |filename|
+        return filename if File.file?(filename)
+      end
+    end
+
+    def find_directory(*names)
+      search_up(*names) do |dirname|
+        return dirname if File.directory?(dirname)
+      end
+    end
+
+    def search_up(*names)
+      previous = nil
+      current  = File.expand_path(SharedHelpers.pwd)
+
+      until !File.directory?(current) || current == previous
+        if ENV["BUNDLER_SPEC_RUN"]
+          # avoid stepping above the tmp directory when testing
+          return nil if File.directory?(File.join(current, "tmp"))
+        end
+
+        names.each do |name|
+          filename = File.join(current, name)
+          yield filename
+        end
+        previous = current
+        current = File.expand_path("..", current)
+      end
+    end
+
+    def set_env(key, value)
+      raise ArgumentError, "new key #{key}" unless EnvironmentPreserver::BUNDLER_KEYS.include?(key)
+      orig_key = "#{EnvironmentPreserver::BUNDLER_PREFIX}#{key}"
+      orig = ENV[key]
+      orig ||= EnvironmentPreserver::INTENTIONALLY_NIL
+      ENV[orig_key] ||= orig
+
+      ENV[key] = value
+    end
+    public :set_env
+
+    def set_bundle_variables
+      Bundler::SharedHelpers.set_env "BUNDLE_BIN_PATH", bundle_bin_path
+      Bundler::SharedHelpers.set_env "BUNDLE_GEMFILE", find_gemfile.to_s
+      Bundler::SharedHelpers.set_env "BUNDLE_LOCKFILE", default_lockfile.to_s
+      Bundler::SharedHelpers.set_env "BUNDLER_VERSION", Bundler::VERSION
+      Bundler::SharedHelpers.set_env "BUNDLER_SETUP", File.expand_path("setup", __dir__)
+    end
+
+    def bundle_bin_path
+      # bundler exe & lib folders have same root folder, typical gem installation
+      exe_file = File.join(source_root, "exe/bundle")
+
+      # for Ruby core repository testing
+      exe_file = File.join(source_root, "libexec/bundle") unless File.exist?(exe_file)
+
+      # bundler is a default gem, exe path is separate
+      exe_file = Gem.bin_path("bundler", "bundle", VERSION) unless File.exist?(exe_file)
+
+      exe_file
+    end
+    public :bundle_bin_path
+
+    def gemspec_path
+      # inside a gem repository, typical gem installation
+      gemspec_file = File.join(source_root, "../../specifications/bundler-#{VERSION}.gemspec")
+
+      # for Ruby core repository testing
+      gemspec_file = File.expand_path("bundler.gemspec", __dir__) unless File.exist?(gemspec_file)
+
+      # bundler is a default gem
+      gemspec_file = File.join(Gem.default_specifications_dir, "bundler-#{VERSION}.gemspec") unless File.exist?(gemspec_file)
+
+      gemspec_file
+    end
+    public :gemspec_path
+
+    def source_root
+      File.expand_path("../..", __dir__)
+    end
+
+    def set_path
+      validate_bundle_path
+      paths = (ENV["PATH"] || "").split(File::PATH_SEPARATOR)
+      paths.unshift "#{Bundler.bundle_path}/bin"
+      Bundler::SharedHelpers.set_env "PATH", paths.uniq.join(File::PATH_SEPARATOR)
+    end
+
+    def set_rubyopt
+      rubyopt = [ENV["RUBYOPT"]].compact
+      setup_require = "-r#{File.expand_path("setup", __dir__)}"
+      return if !rubyopt.empty? && rubyopt.first.include?(setup_require)
+      rubyopt.unshift setup_require
+      Bundler::SharedHelpers.set_env "RUBYOPT", rubyopt.join(" ")
+    end
+
+    def set_rubylib
+      rubylib = (ENV["RUBYLIB"] || "").split(File::PATH_SEPARATOR)
+      rubylib.unshift bundler_ruby_lib unless RbConfig::CONFIG["rubylibdir"] == bundler_ruby_lib
+      Bundler::SharedHelpers.set_env "RUBYLIB", rubylib.uniq.join(File::PATH_SEPARATOR)
+    end
+
+    def bundler_ruby_lib
+      File.expand_path("..", __dir__)
+    end
+
+    def clean_load_path
+      loaded_gem_paths = Bundler.rubygems.loaded_gem_paths
+
+      $LOAD_PATH.reject! do |p|
+        resolved_path = resolve_path(p)
+        next if $LOADED_FEATURES.any? {|lf| lf.start_with?(resolved_path) }
+        loaded_gem_paths.delete(p)
+      end
+      $LOAD_PATH.uniq!
+    end
+
+    def resolve_path(path)
+      expanded = File.expand_path(path)
+      return expanded unless File.exist?(expanded)
+
+      File.realpath(expanded)
+    end
+
+    def prints_major_deprecations?
+      return false if Bundler.settings[:silence_deprecations]
+      require_relative "deprecate"
+      return false if Bundler::Deprecate.skip
+      true
+    end
+
+    extend self
+  end
+end
diff --git a/lib/bundler/source.rb b/lib/bundler/source.rb
new file mode 100644
index 0000000000..cf71be8801
--- /dev/null
+++ b/lib/bundler/source.rb
@@ -0,0 +1,120 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Source
+    autoload :Gemspec,  File.expand_path("source/gemspec", __dir__)
+    autoload :Git,      File.expand_path("source/git", __dir__)
+    autoload :Metadata, File.expand_path("source/metadata", __dir__)
+    autoload :Path,     File.expand_path("source/path", __dir__)
+    autoload :Rubygems, File.expand_path("source/rubygems", __dir__)
+    autoload :RubygemsAggregate, File.expand_path("source/rubygems_aggregate", __dir__)
+
+    attr_accessor :dependency_names
+
+    attr_reader :checksum_store
+
+    def unmet_deps
+      specs.unmet_dependency_names
+    end
+
+    def version_message(spec, locked_spec = nil)
+      message = "#{spec.name} #{spec.version}"
+      message += " (#{spec.platform})" if spec.platform != Gem::Platform::RUBY && !spec.platform.nil?
+
+      if locked_spec
+        locked_spec_version = locked_spec.version
+        if locked_spec_version && spec.version != locked_spec_version
+          message += Bundler.ui.add_color(" (was #{locked_spec_version})", version_color(spec.version, locked_spec_version))
+        end
+      end
+
+      message
+    end
+
+    def download(*); end
+
+    def can_lock?(spec)
+      spec.source == self
+    end
+
+    def prefer_local!; end
+
+    def local!; end
+
+    def local_only!; end
+
+    def cached!; end
+
+    def remote!; end
+
+    def add_dependency_names(names)
+      @dependency_names = Array(dependency_names) | Array(names)
+    end
+
+    # it's possible that gems from one source depend on gems from some
+    # other source, so now we download gemspecs and iterate over those
+    # dependencies, looking for gems we don't have info on yet.
+    def double_check_for(*); end
+
+    def dependency_names_to_double_check
+      specs.dependency_names
+    end
+
+    def spec_names
+      specs.spec_names
+    end
+
+    def include?(other)
+      other == self
+    end
+
+    def inspect
+      "#<#{self.class}:0x#{object_id} #{self}>"
+    end
+
+    def identifier
+      to_s
+    end
+
+    def path?
+      instance_of?(Bundler::Source::Path)
+    end
+
+    def extension_cache_path(spec)
+      return unless Bundler.settings[:global_gem_cache]
+      return unless source_slug = extension_cache_slug(spec)
+      Bundler.user_cache.join(
+        "extensions", Gem::Platform.local.to_s, Bundler.ruby_scope,
+        source_slug, spec.full_name
+      )
+    end
+
+    private
+
+    def version_color(spec_version, locked_spec_version)
+      if Gem::Version.correct?(spec_version) && Gem::Version.correct?(locked_spec_version)
+        # display yellow if there appears to be a regression
+        earlier_version?(spec_version, locked_spec_version) ? :yellow : :green
+      else
+        # default to green if the versions cannot be directly compared
+        :green
+      end
+    end
+
+    def earlier_version?(spec_version, locked_spec_version)
+      Gem::Version.new(spec_version) < Gem::Version.new(locked_spec_version)
+    end
+
+    def print_using_message(message)
+      if !message.include?("(was ")
+        Bundler.ui.debug message
+      else
+        Bundler.ui.info message
+      end
+    end
+
+    def extension_cache_slug(_)
+      nil
+    end
+  end
+end
diff --git a/lib/bundler/source/gemspec.rb b/lib/bundler/source/gemspec.rb
new file mode 100644
index 0000000000..ed766dbe74
--- /dev/null
+++ b/lib/bundler/source/gemspec.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Source
+    class Gemspec < Path
+      attr_reader :gemspec
+      attr_writer :checksum_store
+
+      def initialize(options)
+        super
+        @gemspec = options["gemspec"]
+      end
+
+      def to_s
+        "gemspec at `#{@path}`"
+      end
+    end
+  end
+end
diff --git a/lib/bundler/source/git.rb b/lib/bundler/source/git.rb
new file mode 100644
index 0000000000..a002a2570a
--- /dev/null
+++ b/lib/bundler/source/git.rb
@@ -0,0 +1,456 @@
+# frozen_string_literal: true
+
+require_relative "../vendored_fileutils"
+
+module Bundler
+  class Source
+    class Git < Path
+      autoload :GitProxy, File.expand_path("git/git_proxy", __dir__)
+
+      attr_reader :uri, :ref, :branch, :options, :glob, :submodules
+
+      def initialize(options)
+        @options = options
+        @checksum_store = Checksum::Store.new
+        @glob = options["glob"] || DEFAULT_GLOB
+
+        @allow_cached = false
+        @allow_remote = false
+
+        # Stringify options that could be set as symbols
+        %w[ref branch tag revision].each {|k| options[k] = options[k].to_s if options[k] }
+
+        @uri        = URINormalizer.normalize_suffix(options["uri"] || "", trailing_slash: false)
+        @safe_uri   = URICredentialsFilter.credential_filtered_uri(@uri)
+        @branch     = options["branch"]
+        @ref        = options["ref"] || options["branch"] || options["tag"]
+        @submodules = options["submodules"]
+        @name       = options["name"]
+        @version    = options["version"].to_s.strip.gsub("-", ".pre.")
+
+        @copied     = false
+        @local      = false
+      end
+
+      def remote!
+        return if @allow_remote
+
+        @local_specs = nil
+        @allow_remote = true
+      end
+
+      def cached!
+        return if @allow_cached
+
+        @local_specs = nil
+        @allow_cached = true
+      end
+
+      def self.from_lock(options)
+        new(options.merge("uri" => options.delete("remote")))
+      end
+
+      def to_lock
+        out = String.new("GIT\n")
+        out << "  remote: #{@uri}\n"
+        out << "  revision: #{revision}\n"
+        %w[ref branch tag submodules].each do |opt|
+          out << "  #{opt}: #{options[opt]}\n" if options[opt]
+        end
+        out << "  glob: #{@glob}\n" unless default_glob?
+        out << "  specs:\n"
+      end
+
+      def to_gemfile
+        specifiers = %w[ref branch tag submodules glob].map do |opt|
+          "#{opt}: #{options[opt]}" if options[opt]
+        end
+
+        uri_with_specifiers(specifiers)
+      end
+
+      def hash
+        [self.class, uri, ref, branch, name, glob, submodules].hash
+      end
+
+      def eql?(other)
+        other.is_a?(Git) && uri == other.uri && ref == other.ref &&
+          branch == other.branch && name == other.name &&
+          glob == other.glob &&
+          submodules == other.submodules
+      end
+
+      alias_method :==, :eql?
+
+      def include?(other)
+        other.is_a?(Git) && uri == other.uri &&
+          name == other.name &&
+          glob == other.glob &&
+          submodules == other.submodules
+      end
+
+      def to_s
+        begin
+          at = humanized_ref || current_branch
+
+          rev = "at #{at}@#{shortref_for_display(revision)}"
+        rescue GitError
+          ""
+        end
+
+        uri_with_specifiers([rev, glob_for_display])
+      end
+
+      def identifier
+        uri_with_specifiers([humanized_ref, locked_revision, glob_for_display])
+      end
+
+      def uri_with_specifiers(specifiers)
+        specifiers.compact!
+
+        suffix =
+          if specifiers.any?
+            " (#{specifiers.join(", ")})"
+          else
+            ""
+          end
+
+        "#{@safe_uri}#{suffix}"
+      end
+
+      def name
+        File.basename(@uri, ".git")
+      end
+
+      # This is the path which is going to contain a specific
+      # checkout of the git repository. When using local git
+      # repos, this is set to the local repo.
+      def install_path
+        @install_path ||= begin
+          git_scope = "#{base_name}-#{shortref_for_path(revision)}"
+
+          Bundler.install_path.join(git_scope)
+        end
+      end
+
+      alias_method :path, :install_path
+
+      def extension_dir_name
+        "#{base_name}-#{shortref_for_path(revision)}"
+      end
+
+      def unlock!
+        git_proxy.revision = nil
+        options["revision"] = nil
+
+        @unlocked = true
+      end
+
+      def local_override!(path)
+        return false if local?
+
+        original_path = path
+        path = Pathname.new(path)
+        path = path.expand_path(Bundler.root) unless path.relative?
+
+        unless branch || Bundler.settings[:disable_local_branch_check]
+          raise GitError, "Cannot use local override for #{name} at #{path} because " \
+            ":branch is not specified in Gemfile. Specify a branch or run " \
+            "`bundle config unset local.#{override_for(original_path)}` to remove the local override"
+        end
+
+        unless path.exist?
+          raise GitError, "Cannot use local override for #{name} because #{path} " \
+            "does not exist. Run `bundle config unset local.#{override_for(original_path)}` to remove the local override"
+        end
+
+        @local = true
+        set_paths!(path)
+
+        # Create a new git proxy without the cached revision
+        # so the Gemfile.lock always picks up the new revision.
+        @git_proxy = GitProxy.new(path, uri, options)
+
+        if current_branch != branch && !Bundler.settings[:disable_local_branch_check]
+          raise GitError, "Local override for #{name} at #{path} is using branch " \
+            "#{current_branch} but Gemfile specifies #{branch}"
+        end
+
+        changed = locked_revision && locked_revision != revision
+
+        if !Bundler.settings[:disable_local_revision_check] && changed && !@unlocked && !git_proxy.contains?(locked_revision)
+          raise GitError, "The Gemfile lock is pointing to revision #{shortref_for_display(locked_revision)} " \
+            "but the current branch in your local override for #{name} does not contain such commit. " \
+            "Please make sure your branch is up to date."
+        end
+
+        changed
+      end
+
+      def specs(*)
+        set_cache_path!(app_cache_path) if use_app_cache?
+
+        if requires_checkout? && !@copied
+          Plugin.hook(Plugin::Events::GIT_BEFORE_FETCH, self)
+          begin
+            fetch unless use_app_cache?
+            checkout
+          ensure
+            Plugin.hook(Plugin::Events::GIT_AFTER_FETCH, self)
+          end
+        end
+
+        local_specs
+      end
+
+      def install(spec, options = {})
+        return if Bundler.settings[:no_install]
+        force = options[:force]
+
+        print_using_message "Using #{version_message(spec, options[:previous_spec])} from #{self}"
+
+        if (requires_checkout? && !@copied) || force
+          checkout
+        end
+
+        generate_bin_options = { disable_extensions: !spec.missing_extensions?, build_args: options[:build_args] }
+        generate_bin(spec, generate_bin_options)
+
+        requires_checkout? ? spec.post_install_message : nil
+      end
+
+      def migrate_cache(custom_path = nil, local: false)
+        if local
+          cache_to(custom_path, try_migrate: false)
+        else
+          cache_to(custom_path, try_migrate: true)
+        end
+      end
+
+      def cache(spec, custom_path = nil)
+        cache_to(custom_path, try_migrate: false)
+      end
+
+      def load_spec_files
+        super
+      rescue PathError => e
+        Bundler.ui.trace e
+        raise GitError, "#{self} is not yet checked out. Run `bundle install` first."
+      end
+
+      # This is the path which is going to contain a cache
+      # of the git repository. When using the same git repository
+      # across different projects, this cache will be shared.
+      # When using local git repos, this is set to the local repo.
+      def cache_path
+        @cache_path ||= if Bundler.settings[:global_gem_cache]
+          Bundler.user_cache
+        else
+          Bundler.bundle_path.join("cache", "bundler")
+        end.join("git", git_scope)
+      end
+
+      def app_cache_dirname
+        "#{base_name}-#{shortref_for_path(locked_revision || revision)}"
+      end
+
+      def revision
+        git_proxy.revision
+      end
+
+      def current_branch
+        git_proxy.current_branch
+      end
+
+      def allow_git_ops?
+        @allow_remote || @allow_cached
+      end
+
+      def local?
+        @local
+      end
+
+      private
+
+      def cache_to(custom_path, try_migrate: false)
+        return unless Bundler.settings[:cache_all]
+
+        app_cache_path = app_cache_path(custom_path)
+
+        migrate = try_migrate ? bare_repo?(app_cache_path) : false
+
+        set_cache_path!(nil) if migrate
+
+        return if cache_path == app_cache_path
+
+        cached!
+        FileUtils.rm_rf(app_cache_path)
+        git_proxy.checkout if migrate || requires_checkout?
+        git_proxy.copy_to(app_cache_path, @submodules)
+        serialize_gemspecs_in(app_cache_path)
+      end
+
+      def checkout
+        Bundler.ui.debug "  * Checking out revision: #{ref}"
+        if use_app_cache? && !bare_repo?(app_cache_path)
+          SharedHelpers.filesystem_access(install_path.dirname) do |p|
+            FileUtils.mkdir_p(p)
+          end
+          FileUtils.cp_r("#{app_cache_path}/.", install_path)
+        else
+          if use_app_cache? && bare_repo?(app_cache_path)
+            Bundler.ui.warn "Installing from cache in old \"bare repository\" format for compatibility. " \
+                            "Please run `bundle cache` and commit the updated cache to migrate to the new format and get rid of this warning."
+          end
+
+          git_proxy.copy_to(install_path, submodules)
+        end
+        serialize_gemspecs_in(install_path)
+        @copied = true
+      end
+
+      def humanized_ref
+        if local?
+          path
+        elsif user_ref = options["ref"]
+          if /\A[a-z0-9]{4,}\z/i.match?(ref)
+            shortref_for_display(user_ref)
+          else
+            user_ref
+          end
+        elsif ref
+          ref
+        end
+      end
+
+      def serialize_gemspecs_in(destination)
+        destination = destination.expand_path(Bundler.root) if destination.relative?
+        Dir["#{destination}/#{@glob}"].each do |spec_path|
+          # Evaluate gemspecs and cache the result. Gemspecs
+          # in git might require git or other dependencies.
+          # The gemspecs we cache should already be evaluated.
+          spec = Bundler.load_gemspec(spec_path)
+          next unless spec
+          spec.installed_by_version = Gem::VERSION
+          Bundler.rubygems.validate(spec)
+          File.open(spec_path, "wb") {|file| file.write(spec.to_ruby) }
+        end
+      end
+
+      def set_paths!(path)
+        set_cache_path!(path)
+        set_install_path!(path)
+      end
+
+      def set_cache_path!(path)
+        @git_proxy = nil
+        @cache_path = path
+      end
+
+      def set_install_path!(path)
+        @local_specs = nil
+        @install_path = path
+      end
+
+      def has_app_cache?
+        locked_revision && super
+      end
+
+      def use_app_cache?
+        has_app_cache? && !local?
+      end
+
+      def requires_checkout?
+        allow_git_ops? && !local? && !locked_revision_checked_out?
+      end
+
+      def locked_revision_checked_out?
+        locked_revision && locked_revision == revision && installed?
+      end
+
+      def installed?
+        git_proxy.installed_to?(install_path)
+      end
+
+      def base_name
+        File.basename(uri.sub(%r{^(\w+://)?([^/:]+:)?(//\w*/)?(\w*/)*}, ""), ".git")
+      end
+
+      def shortref_for_display(ref)
+        ref[0..6]
+      end
+
+      def shortref_for_path(ref)
+        ref[0..11]
+      end
+
+      def glob_for_display
+        default_glob? ? nil : "glob: #{@glob}"
+      end
+
+      def default_glob?
+        @glob == DEFAULT_GLOB
+      end
+
+      def uri_hash
+        if %r{^\w+://(\w+@)?}.match?(uri)
+          # Downcase the domain component of the URI
+          # and strip off a trailing slash, if one is present
+          input = Gem::URI.parse(uri).normalize.to_s.sub(%r{/$}, "")
+        else
+          # If there is no URI scheme, assume it is an ssh/git URI
+          input = uri
+        end
+        # We use SHA1 here for historical reason and to preserve backward compatibility.
+        # But a transition to a simpler mangling algorithm would be welcome.
+        Bundler::Digest.sha1(input)
+      end
+
+      def locked_revision
+        options["revision"]
+      end
+
+      def cached?
+        cache_path.exist?
+      end
+
+      def git_proxy
+        @git_proxy ||= GitProxy.new(cache_path, uri, options, locked_revision, self)
+      end
+
+      def fetch
+        git_proxy.checkout
+      rescue GitError => e
+        Bundler.ui.warn "Using cached git data because of network errors:\n#{e}"
+      end
+
+      # no-op, since we validate when re-serializing the gemspec
+      def validate_spec(_spec); end
+
+      def load_gemspec(file)
+        dirname = Pathname.new(file).dirname
+        SharedHelpers.chdir(dirname.to_s) do
+          stub = Gem::StubSpecification.gemspec_stub(file, install_path.parent, install_path.parent)
+          stub.full_gem_path = dirname.expand_path(root).to_s
+          StubSpecification.from_stub(stub)
+        end
+      end
+
+      def git_scope
+        "#{base_name}-#{uri_hash}"
+      end
+
+      def extension_cache_slug(_)
+        extension_dir_name
+      end
+
+      def override_for(path)
+        Bundler.settings.local_overrides.key(path)
+      end
+
+      def bare_repo?(path)
+        File.exist?(path.join("objects")) && File.exist?(path.join("HEAD"))
+      end
+    end
+  end
+end
diff --git a/lib/bundler/source/git/git_proxy.rb b/lib/bundler/source/git/git_proxy.rb
new file mode 100644
index 0000000000..8094dcaa9d
--- /dev/null
+++ b/lib/bundler/source/git/git_proxy.rb
@@ -0,0 +1,503 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Source
+    class Git
+      class GitNotInstalledError < GitError
+        def initialize
+          msg = String.new
+          msg << "You need to install git to be able to use gems from git repositories. "
+          msg << "For help installing git, please refer to GitHub's tutorial at https://help.github.com/articles/set-up-git"
+          super msg
+        end
+      end
+
+      class GitNotAllowedError < GitError
+        def initialize(command)
+          msg = String.new
+          msg << "Bundler is trying to run `#{command}` at runtime. You probably need to run `bundle install`. However, "
+          msg << "this error message could probably be more useful. Please submit a ticket at https://github.com/ruby/rubygems/issues/new?labels=Bundler&template=bundler-related-issue.md "
+          msg << "with steps to reproduce as well as the following\n\nCALLER: #{caller.join("\n")}"
+          super msg
+        end
+      end
+
+      class GitCommandError < GitError
+        attr_reader :command
+
+        def initialize(command, path, extra_info = nil)
+          @command = command
+
+          msg = String.new("Git error: command `#{command}`")
+          msg << " in directory #{path}" if path
+          msg << " has failed."
+          msg << "\n#{extra_info}" if extra_info
+          super msg
+        end
+      end
+
+      class MissingGitRevisionError < GitCommandError
+        def initialize(command, destination_path, ref, repo)
+          msg = "Revision #{ref} does not exist in the repository #{repo}. Maybe you misspelled it?"
+          super command, destination_path, msg
+        end
+      end
+
+      class AmbiguousGitReference < GitError
+        def initialize(options)
+          msg = "Specification of branch or ref with tag is ambiguous. You specified #{options.inspect}"
+          super msg
+        end
+      end
+
+      # The GitProxy is responsible to interact with git repositories.
+      # All actions required by the Git source is encapsulated in this
+      # object.
+      class GitProxy
+        attr_accessor :path, :uri, :branch, :tag, :ref, :explicit_ref
+        attr_writer :revision
+
+        def self.version
+          @version ||= full_version[/((\.?\d+)+).*/, 1]
+        end
+
+        def self.full_version
+          @full_version ||= begin
+            raise GitNotInstalledError.new unless Bundler.git_present?
+
+            require "open3"
+            out, err, status = Open3.capture3("git", "--version")
+
+            raise GitCommandError.new("--version", SharedHelpers.pwd, err) unless status.success?
+            Bundler.ui.warn err unless err.empty?
+
+            out.sub(/git version\s*/, "").strip
+          end
+        end
+
+        def self.reset
+          @version = nil
+          @full_version = nil
+        end
+
+        def initialize(path, uri, options = {}, revision = nil, git = nil)
+          @path     = path
+          @uri      = uri
+          @tag      = options["tag"]
+          @branch   = options["branch"]
+          @ref      = options["ref"]
+          if @tag
+            raise AmbiguousGitReference.new(options) if @branch || @ref
+            @explicit_ref = @tag
+          else
+            @explicit_ref = @ref || @branch
+          end
+          @revision = revision
+          @git      = git
+          @commit_ref = nil
+        end
+
+        def revision
+          @revision ||= allowed_with_path { find_local_revision }
+        end
+
+        def current_branch
+          @current_branch ||= with_path do
+            git_local("rev-parse", "--abbrev-ref", "HEAD", dir: path).strip
+          end
+        end
+
+        def contains?(commit)
+          allowed_with_path do
+            result, status = git_null("branch", "--contains", commit, dir: path)
+            status.success? && result.match?(/^\* (.*)$/)
+          end
+        end
+
+        def version
+          self.class.version
+        end
+
+        def full_version
+          self.class.full_version
+        end
+
+        def checkout
+          return if has_revision_cached?
+
+          Bundler.ui.info "Fetching #{credential_filtered_uri}"
+
+          extra_fetch_needed = clone_needs_extra_fetch?
+          unshallow_needed = clone_needs_unshallow?
+          return unless extra_fetch_needed || unshallow_needed
+
+          git_remote_fetch(unshallow_needed ? ["--unshallow"] : depth_args)
+        end
+
+        def copy_to(destination, submodules = false)
+          unless File.exist?(destination.join(".git"))
+            begin
+              SharedHelpers.filesystem_access(destination.dirname) do |p|
+                FileUtils.mkdir_p(p)
+              end
+              SharedHelpers.filesystem_access(destination) do |p|
+                FileUtils.rm_rf(p)
+              end
+              git "clone", "--no-checkout", "--quiet", path.to_s, destination.to_s
+              File.chmod((File.stat(destination).mode | 0o777) & ~File.umask, destination)
+            rescue Errno::EEXIST => e
+              file_path = e.message[%r{.*?((?:[a-zA-Z]:)?/.*)}, 1]
+              raise GitError, "Bundler could not install a gem because it needs to " \
+                "create a directory, but a file exists - #{file_path}. Please delete " \
+                "this file and try again."
+            end
+          end
+
+          ref = @commit_ref || (locked_to_full_sha? && @revision)
+          if ref
+            git "config", "uploadpack.allowAnySHA1InWant", "true", dir: path.to_s if @commit_ref.nil? && needs_allow_any_sha1_in_want?
+
+            git "fetch", "--force", "--quiet", *extra_fetch_args(ref), dir: destination
+          end
+
+          git "reset", "--hard", revision, dir: destination
+
+          if submodules
+            git_retry "submodule", "update", "--init", "--recursive", dir: destination
+          elsif Gem::Version.create(version) >= Gem::Version.create("2.9.0")
+            inner_command = "git -C $toplevel submodule deinit --force $sm_path"
+            git_retry "submodule", "foreach", "--quiet", inner_command, dir: destination
+          end
+        end
+
+        def installed_to?(destination)
+          # if copy_to is interrupted, it may leave a partially installed directory that
+          # contains .git but no other files -- consider this not to be installed
+          Dir.exist?(destination) && (Dir.children(destination) - [".git"]).any?
+        end
+
+        private
+
+        def git_remote_fetch(args)
+          command = fetch_command(args)
+          command_with_no_credentials = check_allowed(command)
+
+          Bundler::Retry.new("`#{command_with_no_credentials}` at #{path}", [MissingGitRevisionError]).attempts do
+            out, err, status = capture(command, path)
+            return out if status.success?
+
+            if err.include?("couldn't find remote ref") || err.include?("not our ref")
+              raise MissingGitRevisionError.new(command_with_no_credentials, path, commit || explicit_ref, credential_filtered_uri)
+            else
+              if shallow?
+                args -= depth_args
+                command = fetch_command(args)
+                command_with_no_credentials = check_allowed(command)
+              end
+              raise GitCommandError.new(command_with_no_credentials, path, err)
+            end
+          end
+        end
+
+        def clone_needs_extra_fetch?
+          return true if path.exist?
+
+          SharedHelpers.filesystem_access(path.dirname) do |p|
+            FileUtils.mkdir_p(p)
+          end
+
+          clone_args = extra_clone_args
+          command = clone_command(clone_args)
+          command_with_no_credentials = check_allowed(command)
+
+          Bundler::Retry.new("`#{command_with_no_credentials}`", [MissingGitRevisionError]).attempts do
+            _, err, status = capture(command, nil)
+            return extra_ref if status.success?
+
+            if err.include?("Could not find remote branch") || # git up to 2.49
+               err.include?("Remote branch #{branch_option} not found") # git 2.49 or higher
+              raise MissingGitRevisionError.new(command_with_no_credentials, nil, explicit_ref, credential_filtered_uri)
+            else
+              if shallow?
+                clone_args -= depth_args
+                command = clone_command(clone_args)
+                command_with_no_credentials = check_allowed(command)
+              end
+              raise GitCommandError.new(command_with_no_credentials, path, err)
+            end
+          end
+        end
+
+        def clone_needs_unshallow?
+          return false unless path.join("shallow").exist?
+          return true unless shallow?
+
+          @revision && @revision != head_revision
+        end
+
+        def extra_ref
+          return false if not_pinned?
+          return true if shallow?
+
+          ref.start_with?("refs/")
+        end
+
+        def depth
+          return @depth if defined?(@depth)
+
+          @depth = if !supports_fetching_unreachable_refs?
+            nil
+          elsif not_pinned? || pinned_to_full_sha?
+            1
+          elsif ref.include?("~")
+            parsed_depth = ref.split("~").last
+            parsed_depth.to_i + 1
+          end
+        end
+
+        def refspec
+          if commit
+            @commit_ref = "refs/#{commit}-sha"
+            return "#{commit}:#{@commit_ref}"
+          end
+
+          reference = fully_qualified_ref
+
+          reference ||= if ref.include?("~")
+            ref.split("~").first
+          elsif ref.start_with?("refs/")
+            ref
+          else
+            "refs/*"
+          end
+
+          "#{reference}:#{reference}"
+        end
+
+        def commit
+          @commit ||= pinned_to_full_sha? ? ref : @revision
+        end
+
+        def fully_qualified_ref
+          if branch
+            "refs/heads/#{branch}"
+          elsif tag
+            "refs/tags/#{tag}"
+          elsif ref.nil?
+            "refs/heads/#{current_branch}"
+          end
+        end
+
+        def not_pinned?
+          branch_option || ref.nil?
+        end
+
+        def pinned_to_full_sha?
+          full_sha_revision?(ref)
+        end
+
+        def locked_to_full_sha?
+          full_sha_revision?(@revision)
+        end
+
+        def full_sha_revision?(ref)
+          ref&.match?(/\A\h{40}\z/)
+        end
+
+        def git_null(*command, dir: nil)
+          check_allowed(command)
+
+          capture(command, dir, ignore_err: true)
+        end
+
+        def git_retry(*command, dir: nil)
+          command_with_no_credentials = check_allowed(command)
+
+          Bundler::Retry.new("`#{command_with_no_credentials}` at #{dir || SharedHelpers.pwd}").attempts do
+            git(*command, dir: dir)
+          end
+        end
+
+        def git(*command, dir: nil)
+          run_command(*command, dir: dir) do |unredacted_command|
+            check_allowed(unredacted_command)
+          end
+        end
+
+        def git_local(*command, dir: nil)
+          run_command(*command, dir: dir) do |unredacted_command|
+            redact_and_check_presence(unredacted_command)
+          end
+        end
+
+        def has_revision_cached?
+          return unless commit && path.exist?
+          git("cat-file", "-e", commit, dir: path)
+          true
+        rescue GitError
+          false
+        end
+
+        def find_local_revision
+          return head_revision if explicit_ref.nil?
+
+          find_revision_for(explicit_ref)
+        end
+
+        def head_revision
+          verify("HEAD")
+        end
+
+        def find_revision_for(reference)
+          verify(reference)
+        rescue GitCommandError => e
+          raise MissingGitRevisionError.new(e.command, path, reference, credential_filtered_uri)
+        end
+
+        def verify(reference)
+          git("rev-parse", "--verify", reference, dir: path).strip
+        end
+
+        # Adds credentials to the URI
+        def configured_uri
+          if /https?:/.match?(uri)
+            remote = Gem::URI(uri)
+            config_auth = Bundler.settings[remote.to_s] || Bundler.settings[remote.host]
+            remote.userinfo ||= config_auth
+            remote.to_s
+          else
+            uri.to_s
+          end
+        end
+
+        # Removes credentials from the URI
+        def credential_filtered_uri
+          URICredentialsFilter.credential_filtered_uri(uri)
+        end
+
+        def allow?
+          allowed = @git ? @git.allow_git_ops? : true
+
+          raise GitNotInstalledError.new if allowed && !Bundler.git_present?
+
+          allowed
+        end
+
+        def with_path(&blk)
+          checkout unless path.exist?
+          blk.call
+        end
+
+        def allowed_with_path
+          return with_path { yield } if allow?
+          raise GitError, "The git source #{uri} is not yet checked out. Please run `bundle install` before trying to start your application"
+        end
+
+        def check_allowed(command)
+          command_with_no_credentials = redact_and_check_presence(command)
+          raise GitNotAllowedError.new(command_with_no_credentials) unless allow?
+          command_with_no_credentials
+        end
+
+        def redact_and_check_presence(command)
+          raise GitNotInstalledError.new unless Bundler.git_present?
+
+          require "shellwords"
+          URICredentialsFilter.credential_filtered_string("git #{command.shelljoin}", uri)
+        end
+
+        def run_command(*command, dir: nil)
+          command_with_no_credentials = yield(command)
+
+          out, err, status = capture(command, dir)
+
+          raise GitCommandError.new(command_with_no_credentials, dir || SharedHelpers.pwd, err) unless status.success?
+
+          Bundler.ui.warn err unless err.empty?
+
+          out
+        end
+
+        def capture(cmd, dir, ignore_err: false)
+          SharedHelpers.with_clean_git_env do
+            require "open3"
+            out, err, status = Open3.capture3(*capture3_args_for(cmd, dir))
+
+            filtered_out = URICredentialsFilter.credential_filtered_string(out, uri)
+            return [filtered_out, status] if ignore_err
+
+            filtered_err = URICredentialsFilter.credential_filtered_string(err, uri)
+            [filtered_out, filtered_err, status]
+          end
+        end
+
+        def capture3_args_for(cmd, dir)
+          # Disable automatic maintenance so a background commit-graph write in
+          # the source repo can't race the hardlinking local clone and fail with
+          # "hardlink different from source".
+          opts = ["-c", "gc.auto=0", "-c", "maintenance.auto=false"]
+
+          return ["git", *opts, *cmd] unless dir
+
+          ["git", "-C", dir.to_s, *opts, *cmd]
+        end
+
+        def extra_clone_args
+          args = depth_args
+          return [] if args.empty?
+
+          args += ["--single-branch"]
+          args.unshift("--no-tags") if supports_cloning_with_no_tags?
+
+          # If there's a locked revision, no need to clone any specific branch
+          # or tag, since we will end up checking out that locked revision
+          # anyways.
+          return args if @revision
+
+          args += ["--branch", branch_option] if branch_option
+          args
+        end
+
+        def fetch_command(args)
+          ["fetch", "--force", "--quiet", "--no-tags", *args, "--", configured_uri, refspec].compact
+        end
+
+        def clone_command(args)
+          ["clone", "--bare", "--no-hardlinks", "--quiet", *args, "--", configured_uri, path.to_s]
+        end
+
+        def depth_args
+          return [] unless shallow?
+
+          ["--depth", depth.to_s]
+        end
+
+        def extra_fetch_args(ref)
+          extra_args = [path.to_s, *depth_args]
+          extra_args.push(ref)
+          extra_args
+        end
+
+        def branch_option
+          branch || tag
+        end
+
+        def shallow?
+          !depth.nil?
+        end
+
+        def needs_allow_any_sha1_in_want?
+          @needs_allow_any_sha1_in_want ||= Gem::Version.new(version) <= Gem::Version.new("2.13.7")
+        end
+
+        def supports_fetching_unreachable_refs?
+          @supports_fetching_unreachable_refs ||= Gem::Version.new(version) >= Gem::Version.new("2.5.0")
+        end
+
+        def supports_cloning_with_no_tags?
+          @supports_cloning_with_no_tags ||= Gem::Version.new(version) >= Gem::Version.new("2.14.0-rc0")
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/source/metadata.rb b/lib/bundler/source/metadata.rb
new file mode 100644
index 0000000000..ecf8895187
--- /dev/null
+++ b/lib/bundler/source/metadata.rb
@@ -0,0 +1,67 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Source
+    class Metadata < Source
+      def specs
+        @specs ||= Index.build do |idx|
+          idx << Gem::Specification.new("Ruby\0", Bundler::RubyVersion.system.gem_version)
+          idx << Gem::Specification.new("RubyGems\0", Gem::VERSION) do |s|
+            s.required_rubygems_version = Gem::Requirement.default
+          end
+
+          if local_spec = Gem.loaded_specs["bundler"]
+            raise CorruptBundlerInstallError.new(local_spec) if local_spec.version.to_s != Bundler::VERSION
+
+            idx << local_spec
+          else
+            idx << Gem::Specification.new do |s|
+              s.name     = "bundler"
+              s.version  = VERSION
+              s.license  = "MIT"
+              s.platform = Gem::Platform::RUBY
+              s.authors  = ["bundler team"]
+              s.bindir   = "exe"
+              s.homepage = "https://bundler.io"
+              s.summary  = "The best way to manage your application's dependencies"
+              s.executables = %w[bundle bundler]
+              s.loaded_from = SharedHelpers.gemspec_path
+            end
+          end
+
+          idx.each {|s| s.source = self }
+        end
+      end
+
+      def options
+        {}
+      end
+
+      def install(spec, _opts = {})
+        print_using_message "Using #{version_message(spec)}"
+        nil
+      end
+
+      def to_s
+        "the local ruby installation"
+      end
+
+      def ==(other)
+        self.class == other.class
+      end
+      alias_method :eql?, :==
+
+      def hash
+        self.class.hash
+      end
+
+      def version_message(spec)
+        "#{spec.name} #{spec.version}"
+      end
+
+      def checksum_store
+        @checksum_store ||= Checksum::Store.new
+      end
+    end
+  end
+end
diff --git a/lib/bundler/source/path.rb b/lib/bundler/source/path.rb
new file mode 100644
index 0000000000..366a23aea7
--- /dev/null
+++ b/lib/bundler/source/path.rb
@@ -0,0 +1,256 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Source
+    class Path < Source
+      autoload :Installer, File.expand_path("path/installer", __dir__)
+
+      attr_reader :path, :options, :root_path, :original_path
+      attr_writer :name
+      attr_accessor :version
+
+      protected :original_path
+
+      DEFAULT_GLOB = "{,*,*/*}.gemspec"
+
+      def initialize(options)
+        @checksum_store = Checksum::Store.new
+        @options = options.dup
+        @glob = options["glob"] || DEFAULT_GLOB
+
+        @root_path = options["root_path"] || root
+
+        if options["path"]
+          @path = Pathname.new(options["path"])
+          expanded_path = expand(@path)
+          @path = if @path.relative?
+            expanded_path.relative_path_from(File.expand_path(root_path))
+          else
+            expanded_path
+          end
+        end
+
+        @name    = options["name"]
+        @version = options["version"]
+
+        # Stores the original path. If at any point we move to the
+        # cached directory, we still have the original path to copy from.
+        @original_path = @path
+      end
+
+      def self.from_lock(options)
+        new(options.merge("path" => options.delete("remote")))
+      end
+
+      def to_lock
+        out = String.new("PATH\n")
+        out << "  remote: #{lockfile_path}\n"
+        out << "  glob: #{@glob}\n" unless @glob == DEFAULT_GLOB
+        out << "  specs:\n"
+      end
+
+      def to_s
+        "source at `#{@path}`"
+      end
+
+      alias_method :identifier, :to_s
+
+      alias_method :to_gemfile, :path
+
+      def hash
+        [self.class, expanded_path, version].hash
+      end
+
+      def eql?(other)
+        [Gemspec, Path].include?(other.class) &&
+          expanded_original_path == other.expanded_original_path &&
+          version == other.version
+      end
+
+      alias_method :==, :eql?
+
+      def name
+        File.basename(expanded_path.to_s)
+      end
+
+      def install(spec, options = {})
+        using_message = "Using #{version_message(spec, options[:previous_spec])} from #{self}"
+        using_message += " and installing its executables" unless spec.executables.empty?
+        print_using_message using_message
+        generate_bin(spec, disable_extensions: true)
+        nil # no post-install message
+      end
+
+      def cache(spec, custom_path = nil)
+        app_cache_path = app_cache_path(custom_path)
+        return unless Bundler.settings[:cache_all]
+        return if expand(@original_path).to_s.index(root_path.to_s + "/") == 0
+
+        unless @original_path.exist?
+          raise GemNotFound, "Can't cache gem #{version_message(spec)} because #{self} is missing!"
+        end
+
+        FileUtils.rm_rf(app_cache_path)
+        FileUtils.cp_r("#{@original_path}/.", app_cache_path)
+        FileUtils.touch(app_cache_path.join(".bundlecache"))
+      end
+
+      def local_specs(*)
+        @local_specs ||= load_spec_files
+      end
+
+      def specs
+        if has_app_cache?
+          @path = app_cache_path
+          @expanded_path = nil # Invalidate
+        end
+        local_specs
+      end
+
+      def app_cache_dirname
+        name
+      end
+
+      def root
+        Bundler.root
+      end
+
+      def expanded_original_path
+        @expanded_original_path ||= expand(original_path)
+      end
+
+      private
+
+      def expanded_path
+        @expanded_path ||= expand(path)
+      end
+
+      def expand(somepath)
+        somepath.expand_path(root_path)
+      rescue ArgumentError => e
+        Bundler.ui.debug(e)
+        raise PathError, "There was an error while trying to use the path " \
+          "`#{somepath}`.\nThe error message was: #{e.message}."
+      end
+
+      def lockfile_path
+        return relative_path(original_path) if original_path.absolute?
+        expand(original_path).relative_path_from(root)
+      end
+
+      def app_cache_path(custom_path = nil)
+        @app_cache_path ||= Bundler.app_cache(custom_path).join(app_cache_dirname)
+      end
+
+      def has_app_cache?
+        SharedHelpers.in_bundle? && app_cache_path.exist?
+      end
+
+      def load_gemspec(file)
+        return unless spec = Bundler.load_gemspec(file)
+        spec.installed_by_version = Gem::VERSION
+        spec
+      end
+
+      def validate_spec(spec)
+        Bundler.rubygems.validate(spec)
+      end
+
+      def load_spec_files
+        index = Index.new
+
+        if File.directory?(expanded_path)
+          # We sort depth-first since `<<` will override the earlier-found specs
+          Gem::Util.glob_files_in_dir(@glob, expanded_path).sort_by {|p| -p.split(File::SEPARATOR).size }.each do |file|
+            next unless spec = load_gemspec(file)
+            spec.source = self
+
+            # The ignore attribute is for ignoring installed gems that don't
+            # have extensions correctly compiled for activation. In the case of
+            # path sources, there's a single version of each gem in the path
+            # source available to Bundler, so we always certainly want to
+            # consider that for activation and never makes sense to ignore it.
+            spec.ignored = false
+
+            # Validation causes extension_dir to be calculated, which depends
+            # on #source, so we validate here instead of load_gemspec
+            validate_spec(spec)
+            index << spec
+          end
+
+          if index.empty? && @name && @version
+            index << Gem::Specification.new do |s|
+              s.name     = @name
+              s.source   = self
+              s.version  = Gem::Version.new(@version)
+              s.platform = Gem::Platform::RUBY
+              s.summary  = "Fake gemspec for #{@name}"
+              s.relative_loaded_from = "#{@name}.gemspec"
+              s.authors = ["no one"]
+              if expanded_path.join("bin").exist?
+                executables = expanded_path.join("bin").children
+                executables.reject! {|p| File.directory?(p) }
+                s.executables = executables.map {|c| c.basename.to_s }
+              end
+            end
+          end
+        else
+          message = String.new("The path `#{expanded_path}` ")
+          message << if File.exist?(expanded_path)
+            "is not a directory."
+          else
+            "does not exist."
+          end
+          raise PathError, message
+        end
+
+        index
+      end
+
+      def relative_path(path = self.path)
+        if path.to_s.start_with?(root_path.to_s)
+          return path.relative_path_from(root_path)
+        end
+        path
+      end
+
+      def generate_bin(spec, options = {})
+        gem_dir = Pathname.new(spec.full_gem_path)
+
+        # Some gem authors put absolute paths in their gemspec
+        # and we have to save them from themselves
+        spec.files = spec.files.filter_map do |path|
+          pathname = Pathname.new(path)
+          next path unless pathname.absolute?
+          next if File.directory?(path)
+          begin
+            pathname.relative_path_from(gem_dir).to_s
+          rescue ArgumentError
+            path
+          end
+        end
+
+        installer = Path::Installer.new(
+          spec,
+          env_shebang: false,
+          disable_extensions: options[:disable_extensions],
+          build_args: options[:build_args],
+          bundler_extension_cache_path: extension_cache_path(spec)
+        )
+        installer.post_install
+      rescue Gem::InvalidSpecificationException => e
+        Bundler.ui.warn "\n#{spec.name} at #{spec.full_gem_path} did not have a valid gemspec.\n" \
+                        "This prevents bundler from installing bins or native extensions, but " \
+                        "that may not affect its functionality."
+
+        if !spec.extensions.empty? && !spec.email.empty?
+          Bundler.ui.warn "If you need to use this package without installing it from a gem " \
+                          "repository, please contact #{spec.email} and ask them " \
+                          "to modify their .gemspec so it can work with `gem build`."
+        end
+
+        Bundler.ui.warn "The validation message from RubyGems was:\n  #{e.message}"
+      end
+    end
+  end
+end
diff --git a/lib/bundler/source/path/installer.rb b/lib/bundler/source/path/installer.rb
new file mode 100644
index 0000000000..39765e5da2
--- /dev/null
+++ b/lib/bundler/source/path/installer.rb
@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+require_relative "../../rubygems_gem_installer"
+
+module Bundler
+  class Source
+    class Path
+      class Installer < Bundler::RubyGemsGemInstaller
+        attr_reader :spec
+
+        def initialize(spec, options = {})
+          @options            = options
+          @spec               = spec
+          @gem_dir            = Bundler.rubygems.path(spec.full_gem_path)
+          @wrappers           = true
+          @env_shebang        = true
+          @format_executable  = options[:format_executable] || false
+          @build_args         = options[:build_args] || Bundler.rubygems.build_args
+          @gem_bin_dir        = "#{Bundler.rubygems.gem_dir}/bin"
+          @disable_extensions = options[:disable_extensions]
+          @bin_dir = @gem_bin_dir
+        end
+
+        def post_install
+          run_hooks(:pre_install)
+
+          unless @disable_extensions || Bundler.settings[:no_build_extension]
+            build_extensions
+            run_hooks(:post_build)
+          end
+
+          generate_bin unless spec.executables.empty?
+
+          run_hooks(:post_install)
+        end
+
+        private
+
+        def run_hooks(type)
+          hooks_meth = "#{type}_hooks"
+          return unless Gem.respond_to?(hooks_meth)
+          Gem.send(hooks_meth).each do |hook|
+            result = hook.call(self)
+            next unless result == false
+            location = " at #{$1}" if hook.inspect =~ /@(.*:\d+)/
+            message = "#{type} hook#{location} failed for #{spec.full_name}"
+            raise InstallHookError, message
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/source/rubygems.rb b/lib/bundler/source/rubygems.rb
new file mode 100644
index 0000000000..ed864604fe
--- /dev/null
+++ b/lib/bundler/source/rubygems.rb
@@ -0,0 +1,598 @@
+# frozen_string_literal: true
+
+require "rubygems/user_interaction"
+
+module Bundler
+  class Source
+    class Rubygems < Source
+      autoload :Remote, File.expand_path("rubygems/remote", __dir__)
+
+      # Ask for X gems per API request
+      API_REQUEST_SIZE = 100
+      REQUIRE_MUTEX = Mutex.new
+
+      attr_accessor :remotes
+
+      def initialize(options = {})
+        @options = options
+        @remotes = []
+        @remote_cooldowns = {}
+        @dependency_names = []
+        @allow_remote = false
+        @allow_cached = false
+        @allow_local = options["allow_local"] || false
+        @prefer_local = false
+        @checksum_store = Checksum::Store.new
+        @gem_installers = {}
+        @gem_installers_mutex = Mutex.new
+
+        cooldown = options["cooldown"]
+        Array(options["remotes"]).reverse_each {|r| add_remote(r, cooldown: cooldown) }
+
+        @lockfile_remotes = @remotes if options["from_lockfile"]
+      end
+
+      def caches
+        @caches ||= [cache_path, *Bundler.rubygems.gem_cache]
+      end
+
+      def prefer_local!
+        @prefer_local = true
+      end
+
+      def local_only!
+        @specs = nil
+        @allow_local = true
+        @allow_cached = false
+        @allow_remote = false
+      end
+
+      def local_only?
+        @allow_local && !@allow_remote
+      end
+
+      def local!
+        return if @allow_local
+
+        @specs = nil
+        @allow_local = true
+      end
+
+      def remote!
+        return if @allow_remote
+
+        @specs = nil
+        @allow_remote = true
+      end
+
+      def cached!
+        return unless File.exist?(cache_path)
+
+        return if @allow_cached
+
+        @specs = nil
+        @allow_cached = true
+      end
+
+      def hash
+        @remotes.hash
+      end
+
+      def eql?(other)
+        other.is_a?(Rubygems) && other.credless_remotes == credless_remotes
+      end
+
+      alias_method :==, :eql?
+
+      def include?(o)
+        o.is_a?(Rubygems) && (o.credless_remotes - credless_remotes).empty?
+      end
+
+      def multiple_remotes?
+        @remotes.size > 1
+      end
+
+      def no_remotes?
+        @remotes.size == 0
+      end
+
+      def can_lock?(spec)
+        return super unless multiple_remotes?
+        include?(spec.source)
+      end
+
+      def options
+        { "remotes" => @remotes.map(&:to_s) }
+      end
+
+      def self.from_lock(options)
+        options["remotes"] = Array(options.delete("remote")).reverse
+        new(options.merge("from_lockfile" => true))
+      end
+
+      def to_lock
+        out = String.new("GEM\n")
+        lockfile_remotes.reverse_each do |remote|
+          out << "  remote: #{remote}\n"
+        end
+        out << "  specs:\n"
+      end
+
+      def to_s
+        if remotes.empty?
+          "locally installed gems"
+        elsif @allow_remote && @allow_cached && @allow_local
+          "rubygems repository #{remote_names}, cached gems or installed locally"
+        elsif @allow_remote && @allow_local
+          "rubygems repository #{remote_names} or installed locally"
+        elsif @allow_remote
+          "rubygems repository #{remote_names}"
+        elsif @allow_cached && @allow_local
+          "cached gems or installed locally"
+        else
+          "locally installed gems"
+        end
+      end
+
+      def identifier
+        if remotes.empty?
+          "locally installed gems"
+        else
+          "rubygems repository #{remote_names}"
+        end
+      end
+      alias_method :name, :identifier
+      alias_method :to_gemfile, :identifier
+
+      def specs
+        @specs ||= begin
+          # remote_specs usually generates a way larger Index than the other
+          # sources, and large_idx.merge! small_idx is way faster than
+          # small_idx.merge! large_idx.
+          index = @allow_remote ? remote_specs.dup : Index.new
+
+          # Snapshot per-version `created_at` from the remote info before installed
+          # / cached specs overwrite the EndpointSpecification objects that carry
+          # it. The cooldown filter consults `created_at` on every candidate, so
+          # local stubs need the published date back-filled to participate.
+          remote_created_at = collect_remote_created_at(index)
+
+          index.merge!(cached_specs) if @allow_cached
+          index.merge!(installed_specs) if @allow_local
+
+          if @allow_local
+            if @prefer_local
+              index.merge!(default_specs)
+            else
+              # complete with default specs, only if not already available in the
+              # index through remote, cached, or installed specs
+              index.use(default_specs)
+            end
+          end
+
+          backfill_created_at(index, remote_created_at) unless remote_created_at.empty?
+
+          index
+        end
+      end
+
+      def download(spec, options = {})
+        if (spec.default_gem? && !cached_built_in_gem(spec, local: options[:local])) || (installed?(spec) && !options[:force])
+          return true
+        end
+
+        installer = rubygems_gem_installer(spec, options)
+
+        if spec.remote
+          s = begin
+            installer.spec
+          rescue Gem::Package::FormatError
+            Bundler.rm_rf(installer.gem)
+            raise
+          rescue Gem::Security::Exception => e
+            raise SecurityError,
+             "The gem #{installer.gem} can't be installed because " \
+             "the security policy didn't allow it, with the message: #{e.message}"
+          end
+
+          spec.__swap__(s)
+        end
+
+        spec
+      end
+
+      def install(spec, options = {})
+        if (spec.default_gem? && !cached_built_in_gem(spec, local: options[:local])) || (installed?(spec) && !options[:force])
+          print_using_message "Using #{version_message(spec, options[:previous_spec])}"
+          return nil # no post-install message
+        end
+
+        return if Bundler.settings[:no_install]
+
+        installer = rubygems_gem_installer(spec, options)
+        spec.source.checksum_store.register(spec, installer.gem_checksum)
+
+        message = "Installing #{version_message(spec, options[:previous_spec])}"
+        message += " with native extensions" if spec.extensions.any?
+        Bundler.ui.confirm message
+
+        installed_spec = nil
+
+        Gem.time("Installed #{spec.name} in", 0, true) do
+          installed_spec = installer.install
+        end
+
+        spec.full_gem_path = installed_spec.full_gem_path
+        spec.loaded_from = installed_spec.loaded_from
+        spec.base_dir = installed_spec.base_dir
+
+        spec.post_install_message
+      end
+
+      def cache(spec, custom_path = nil)
+        cached_path = Bundler.settings[:cache_all_platforms] ? fetch_gem_if_possible(spec) : cached_gem(spec)
+        raise GemNotFound, "Missing gem file '#{spec.file_name}'." unless cached_path
+        return if File.dirname(cached_path) == Bundler.app_cache.to_s
+        Bundler.ui.info "  * #{File.basename(cached_path)}"
+        FileUtils.cp(cached_path, Bundler.app_cache(custom_path))
+      rescue Errno::EACCES => e
+        Bundler.ui.debug(e)
+        raise InstallError, e.message
+      end
+
+      def cached_built_in_gem(spec, local: false)
+        cached_path = cached_gem(spec)
+        if cached_path.nil? && !local
+          remote_spec = remote_specs.search(spec).first
+          if remote_spec
+            cached_path = fetch_gem(remote_spec)
+            spec.remote = remote_spec.remote
+          else
+            Bundler.ui.warn "#{spec.full_name} is built in to Ruby, and can't be cached because your Gemfile doesn't have any sources that contain it."
+          end
+        end
+        cached_path
+      end
+
+      def add_remote(source, cooldown: nil)
+        uri = normalize_uri(source)
+        @remotes.unshift(uri) unless @remotes.include?(uri)
+        @remote_cooldowns[uri] = cooldown if cooldown
+      end
+
+      def cooldown_for(uri)
+        @remote_cooldowns[uri]
+      end
+
+      def spec_names
+        if dependency_api_available?
+          remote_specs.spec_names
+        else
+          []
+        end
+      end
+
+      def unmet_deps
+        if dependency_api_available?
+          remote_specs.unmet_dependency_names
+        else
+          []
+        end
+      end
+
+      def remote_fetchers
+        @remote_fetchers ||= remotes.to_h do |uri|
+          remote = Source::Rubygems::Remote.new(uri, cooldown: cooldown_for(uri))
+          [remote, Bundler::Fetcher.new(remote)]
+        end.freeze
+      end
+
+      def fetchers
+        @fetchers ||= remote_fetchers.values.freeze
+      end
+
+      def double_check_for(unmet_dependency_names)
+        return unless dependency_api_available?
+
+        unmet_dependency_names = unmet_dependency_names.call
+        unless unmet_dependency_names.nil?
+          if api_fetchers.size <= 1
+            # can't do this when there are multiple fetchers because then we might not fetch from _all_
+            # of them
+            unmet_dependency_names -= remote_specs.spec_names # avoid re-fetching things we've already gotten
+          end
+          return if unmet_dependency_names.empty?
+        end
+
+        Bundler.ui.debug "Double checking for #{unmet_dependency_names || "all specs (due to the size of the request)"} in #{self}"
+
+        fetch_names(api_fetchers, unmet_dependency_names, remote_specs)
+
+        specs.use remote_specs
+      end
+
+      def dependency_names_to_double_check
+        names = []
+        remote_specs.each do |spec|
+          case spec
+          when EndpointSpecification, Gem::Specification, StubSpecification, LazySpecification
+            names.concat(spec.runtime_dependencies.map(&:name))
+          when RemoteSpecification # from the full index
+            return nil
+          else
+            raise "unhandled spec type (#{spec.inspect})"
+          end
+        end
+        names
+      end
+
+      def dependency_api_available?
+        @allow_remote && api_fetchers.any?
+      end
+
+      def clear_cache
+        @specs = nil
+        @installed_specs = nil
+        @default_specs = nil
+        @cached_specs = nil
+      end
+
+      protected
+
+      def remote_names
+        remotes.map(&:to_s).join(", ")
+      end
+
+      def credless_remotes
+        remotes.map(&method(:remove_auth))
+      end
+
+      def cached_gem(spec)
+        global_cache_path = download_cache_path(spec)
+        caches << global_cache_path if global_cache_path
+
+        possibilities = caches.map {|p| package_path(p, spec) }
+        possibilities.find {|p| File.exist?(p) }
+      end
+
+      def package_path(cache_path, spec)
+        "#{cache_path}/#{spec.file_name}"
+      end
+
+      def normalize_uri(uri)
+        uri = URINormalizer.normalize_suffix(uri.to_s)
+        require_relative "../vendored_uri"
+        uri = Gem::URI(uri)
+        raise ArgumentError, "The source must be an absolute URI. For example:\n" \
+          "source 'https://rubygems.org'" if !uri.absolute? || (uri.is_a?(Gem::URI::HTTP) && uri.host.nil?)
+        uri
+      end
+
+      def remove_auth(remote)
+        if remote.user || remote.password
+          remote.dup.tap {|uri| uri.user = uri.password = nil }.to_s
+        else
+          remote.to_s
+        end
+      end
+
+      def installed_specs
+        @installed_specs ||= Index.build do |idx|
+          Bundler.rubygems.installed_specs.reverse_each do |spec|
+            spec.source = self
+            next if spec.ignored?
+            idx << spec
+          end
+        end
+      end
+
+      def default_specs
+        @default_specs ||= Index.build do |idx|
+          Bundler.rubygems.default_specs.each do |spec|
+            spec.source = self
+            idx << spec
+          end
+        end
+      end
+
+      def cached_specs
+        @cached_specs ||= begin
+          idx = Index.new
+
+          Dir["#{cache_path}/*.gem"].each do |gemfile|
+            s ||= Bundler.rubygems.spec_from_gem(gemfile)
+            s.source = self
+            idx << s
+          end
+
+          idx
+        end
+      end
+
+      def api_fetchers
+        fetchers.select(&:api_fetcher?)
+      end
+
+      def remote_specs
+        @remote_specs ||= Index.build do |idx|
+          index_fetchers = fetchers - api_fetchers
+
+          if index_fetchers.empty?
+            fetch_names(api_fetchers, dependency_names, idx)
+          else
+            fetch_names(fetchers, nil, idx)
+          end
+        end
+      end
+
+      def fetch_names(fetchers, dependency_names, index)
+        fetchers.each do |f|
+          if dependency_names
+            Bundler.ui.info "Fetching gem metadata from #{URICredentialsFilter.credential_filtered_uri(f.uri)}", Bundler.ui.debug?
+            index.use f.specs_with_retry(dependency_names, self)
+            Bundler.ui.info "" unless Bundler.ui.debug? # new line now that the dots are over
+          else
+            Bundler.ui.info "Fetching source index from #{URICredentialsFilter.credential_filtered_uri(f.uri)}"
+            index.use f.specs_with_retry(nil, self)
+          end
+        end
+      end
+
+      def fetch_gem_if_possible(spec, previous_spec = nil)
+        if spec.remote
+          fetch_gem(spec, previous_spec)
+        else
+          cached_gem(spec)
+        end
+      end
+
+      def fetch_gem(spec, previous_spec = nil)
+        spec.fetch_platform
+
+        cache_path = download_cache_path(spec) || default_cache_path_for(rubygems_dir)
+        gem_path = package_path(cache_path, spec)
+        return gem_path if File.exist?(gem_path)
+
+        SharedHelpers.filesystem_access(cache_path) do |p|
+          FileUtils.mkdir_p(p)
+        end
+        download_gem(spec, cache_path, previous_spec)
+
+        gem_path
+      end
+
+      def installed?(spec)
+        installed_specs[spec].any? && !spec.installation_missing?
+      end
+
+      def rubygems_dir
+        Bundler.bundle_path
+      end
+
+      def default_cache_path_for(dir)
+        "#{dir}/cache"
+      end
+
+      def cache_path
+        Bundler.app_cache
+      end
+
+      private
+
+      def collect_remote_created_at(index)
+        return {} unless @allow_remote
+
+        snapshot = {}
+        index.each do |spec|
+          next unless spec.respond_to?(:created_at) && spec.created_at
+          # Remember the remote that supplied the date too: when a source has
+          # several remotes with different per-URI cooldown settings we must
+          # restore the same one during backfill so `effective_cooldown` agrees.
+          snapshot[[spec.name, spec.version]] = [spec.created_at, spec.remote]
+        end
+        snapshot
+      end
+
+      def backfill_created_at(index, snapshot)
+        index.each do |spec|
+          next unless spec.respond_to?(:created_at=)
+          next if spec.created_at
+          remote_created_at, remote = snapshot[[spec.name, spec.version]]
+          next unless remote_created_at
+          spec.created_at = remote_created_at
+          spec.remote ||= remote if remote && spec.respond_to?(:remote=)
+        end
+      end
+
+      def lockfile_remotes
+        @lockfile_remotes || credless_remotes
+      end
+
+      # Checks if the requested spec exists in the global cache. If it does,
+      # we copy it to the download path, and if it does not, we download it.
+      #
+      # @param  [Specification] spec
+      #         the spec we want to download or retrieve from the cache.
+      #
+      # @param  [String] download_cache_path
+      #         the local directory the .gem will end up in.
+      #
+      # @param  [Specification] previous_spec
+      #         the spec previously locked
+      #
+      def download_gem(spec, download_cache_path, previous_spec = nil)
+        uri = spec.remote.uri
+        Bundler.ui.confirm("Fetching #{version_message(spec, previous_spec)}")
+        gem_remote_fetcher = remote_fetchers.fetch(spec.remote).gem_remote_fetcher
+
+        Plugin.hook(Plugin::Events::GEM_BEFORE_FETCH, spec)
+        begin
+          Gem.time("Downloaded #{spec.name} in", 0, true) do
+            Bundler.rubygems.download_gem(spec, uri, download_cache_path, gem_remote_fetcher)
+          end
+        ensure
+          Plugin.hook(Plugin::Events::GEM_AFTER_FETCH, spec)
+        end
+      end
+
+      # Returns the global cache path of the calling Rubygems::Source object.
+      #
+      # Note that the Source determines the path's subdirectory. We use this
+      # subdirectory in the global cache path so that gems with the same name
+      # -- and possibly different versions -- from different sources are saved
+      # to their respective subdirectories and do not override one another.
+      #
+      # @param  [Gem::Specification] specification
+      #
+      # @return [Pathname] The global cache path.
+      #
+      def download_cache_path(spec)
+        return unless Bundler.settings[:global_gem_cache]
+        return unless remote = spec.remote
+        return unless cache_slug = remote.cache_slug
+
+        if Gem.respond_to?(:global_gem_cache_path)
+          Pathname.new(Gem.global_gem_cache_path).join(cache_slug)
+        else
+          # Fall back to old location for older RubyGems versions
+          Bundler.user_cache.join("gems", cache_slug)
+        end
+      end
+
+      def extension_cache_slug(spec)
+        return unless remote = spec.remote
+        remote.cache_slug
+      end
+
+      # We are using a mutex to read and write from/to the hash.
+      # The reason this double synchronization was added is for performance
+      # and to lock the mutex for the shortest possible amount of time. Otherwise,
+      # all threads are fighting over this mutex and when it gets acquired it gets locked
+      # until a thread finishes downloading a gem, leaving the other threads waiting
+      # doing nothing.
+      def rubygems_gem_installer(spec, options)
+        @gem_installers_mutex.synchronize { @gem_installers[spec.name] } || begin
+          path = fetch_gem_if_possible(spec, options[:previous_spec])
+          raise GemNotFound, "Could not find #{spec.file_name} for installation" unless path
+
+          REQUIRE_MUTEX.synchronize { require_relative "../rubygems_gem_installer" }
+
+          installer = Bundler::RubyGemsGemInstaller.at(
+            path,
+            security_policy: Bundler.rubygems.security_policies[Bundler.settings["trust-policy"]],
+            install_dir: rubygems_dir.to_s,
+            bin_dir: Bundler.system_bindir.to_s,
+            ignore_dependencies: true,
+            wrappers: true,
+            env_shebang: true,
+            build_args: options[:build_args],
+            bundler_extension_cache_path: extension_cache_path(spec),
+            build_extension: Bundler.settings[:no_build_extension] ? false : nil,
+            install_plugin: Bundler.settings[:no_install_plugin] ? false : nil
+          )
+          @gem_installers_mutex.synchronize { @gem_installers[spec.name] ||= installer }
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/source/rubygems/remote.rb b/lib/bundler/source/rubygems/remote.rb
new file mode 100644
index 0000000000..3d847424b7
--- /dev/null
+++ b/lib/bundler/source/rubygems/remote.rb
@@ -0,0 +1,86 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Source
+    class Rubygems
+      class Remote
+        attr_reader :uri, :anonymized_uri, :original_uri, :cooldown
+
+        def initialize(uri, cooldown: nil)
+          orig_uri = uri
+          uri = Bundler.settings.mirror_for(uri)
+          @original_uri = orig_uri if orig_uri != uri
+          fallback_auth = Bundler.settings.credentials_for(uri)
+
+          @uri = apply_auth(uri, fallback_auth).freeze
+          @anonymized_uri = remove_auth(@uri).freeze
+          @cooldown = cooldown
+        end
+
+        # Returns the cooldown days that apply to this remote, resolving the
+        # precedence CLI > config > Gemfile per-source. Returns nil if no
+        # cooldown applies.
+        def effective_cooldown
+          override = Bundler.settings[:cooldown]
+          return override if override
+          @cooldown
+        end
+
+        MAX_CACHE_SLUG_HOST_SIZE = 255 - 1 - 32 # 255 minus dot minus MD5 length
+        private_constant :MAX_CACHE_SLUG_HOST_SIZE
+
+        # @return [String] A slug suitable for use as a cache key for this
+        #         remote.
+        #
+        def cache_slug
+          @cache_slug ||= begin
+            return nil unless SharedHelpers.md5_available?
+
+            cache_uri = original_uri || uri
+
+            host = cache_uri.to_s.start_with?("file://") ? nil : cache_uri.host
+
+            uri_parts = [host, cache_uri.user, cache_uri.port, cache_uri.path]
+            uri_parts.compact!
+            uri_digest = SharedHelpers.digest(:MD5).hexdigest(uri_parts.join("."))
+
+            uri_parts.pop
+            host_parts = uri_parts.join(".")
+            return uri_digest if host_parts.empty?
+
+            shortened_host_parts = host_parts[0...MAX_CACHE_SLUG_HOST_SIZE]
+            [shortened_host_parts, uri_digest].join(".")
+          end
+        end
+
+        def to_s
+          "rubygems remote at #{anonymized_uri}"
+        end
+
+        private
+
+        def apply_auth(uri, auth)
+          if auth && uri.userinfo.nil?
+            uri = uri.dup
+            uri.userinfo = auth
+          end
+
+          uri
+        rescue Gem::URI::InvalidComponentError
+          error_message = "Please CGI escape your usernames and passwords before " \
+                          "setting them for authentication."
+          raise HTTPError.new(error_message)
+        end
+
+        def remove_auth(uri)
+          if uri.userinfo
+            uri = uri.dup
+            uri.user = uri.password = nil
+          end
+
+          uri
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/source/rubygems_aggregate.rb b/lib/bundler/source/rubygems_aggregate.rb
new file mode 100644
index 0000000000..8aeaa375fa
--- /dev/null
+++ b/lib/bundler/source/rubygems_aggregate.rb
@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Source
+    class RubygemsAggregate
+      attr_reader :source_map, :sources
+
+      def initialize(sources, source_map, excluded_sources = [])
+        @sources = sources
+        @source_map = source_map
+        @excluded_sources = excluded_sources
+
+        @index = build_index
+      end
+
+      def specs
+        @index
+      end
+
+      def identifier
+        to_s
+      end
+
+      def to_s
+        "any of the sources"
+      end
+
+      private
+
+      def build_index
+        Index.build do |idx|
+          dependency_names = source_map.pinned_spec_names
+
+          sources.all_sources.each do |source|
+            next if @excluded_sources.include?(source)
+
+            source.dependency_names = dependency_names - source_map.pinned_spec_names(source)
+            idx.add_source source.specs
+            dependency_names.concat(source.unmet_deps).uniq!
+          end
+
+          double_check_for_index(idx, dependency_names)
+        end
+      end
+
+      # Suppose the gem Foo depends on the gem Bar.  Foo exists in Source A.  Bar has some versions that exist in both
+      # sources A and B.  At this point, the API request will have found all the versions of Bar in source A,
+      # but will not have found any versions of Bar from source B, which is a problem if the requested version
+      # of Foo specifically depends on a version of Bar that is only found in source B. This ensures that for
+      # each spec we found, we add all possible versions from all sources to the index.
+      def double_check_for_index(idx, dependency_names)
+        pinned_names = source_map.pinned_spec_names
+
+        names = :names # do this so we only have to traverse to get dependency_names from the index once
+        unmet_dependency_names = lambda do
+          return names unless names == :names
+          new_names = sources.all_sources.map(&:dependency_names_to_double_check)
+          return names = nil if new_names.compact!
+          names = new_names.flatten(1).concat(dependency_names)
+          names.uniq!
+          names -= pinned_names
+          names
+        end
+
+        sources.all_sources.each do |source|
+          source.double_check_for(unmet_dependency_names)
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/source_list.rb b/lib/bundler/source_list.rb
new file mode 100644
index 0000000000..ab7002d6e5
--- /dev/null
+++ b/lib/bundler/source_list.rb
@@ -0,0 +1,232 @@
+# frozen_string_literal: true
+
+module Bundler
+  class SourceList
+    attr_reader :path_sources,
+      :git_sources,
+      :plugin_sources,
+      :global_path_source,
+      :metadata_source
+
+    def global_rubygems_source
+      @global_rubygems_source ||= source_class.new("allow_local" => true)
+    end
+
+    def initialize
+      @path_sources           = []
+      @git_sources            = []
+      @plugin_sources         = []
+      @global_rubygems_source = nil
+      @global_path_source     = nil
+      @rubygems_sources       = []
+      @metadata_source        = Source::Metadata.new
+
+      @local_mode = true
+    end
+
+    def aggregate_global_source?
+      global_rubygems_source.multiple_remotes?
+    end
+
+    def implicit_global_source?
+      global_rubygems_source.no_remotes?
+    end
+
+    def add_path_source(options = {})
+      if options["gemspec"]
+        add_source_to_list Source::Gemspec.new(options), path_sources
+      else
+        path_source = add_source_to_list Source::Path.new(options), path_sources
+        @global_path_source ||= path_source if options["global"]
+        path_source
+      end
+    end
+
+    def add_git_source(options = {})
+      add_source_to_list(Source::Git.new(options), git_sources).tap do |source|
+        warn_on_git_protocol(source)
+      end
+    end
+
+    def add_rubygems_source(options = {})
+      new_source = Source::Rubygems.new(options)
+      return @global_rubygems_source if @global_rubygems_source == new_source
+
+      add_source_to_list new_source, @rubygems_sources
+    end
+
+    def add_plugin_source(source, options = {})
+      add_source_to_list Plugin.source(source).new(options), @plugin_sources
+    end
+
+    def add_global_rubygems_remote(uri, cooldown: nil)
+      global_rubygems_source.add_remote(uri, cooldown: cooldown)
+      global_rubygems_source
+    end
+
+    def local_mode?
+      @local_mode
+    end
+
+    def default_source
+      global_path_source || global_rubygems_source
+    end
+
+    def rubygems_sources
+      non_global_rubygems_sources + [global_rubygems_source]
+    end
+
+    def non_global_rubygems_sources
+      @rubygems_sources
+    end
+
+    def all_sources
+      path_sources + git_sources + plugin_sources + rubygems_sources + [metadata_source]
+    end
+
+    def non_default_explicit_sources
+      all_sources - [default_source, metadata_source]
+    end
+
+    def get(source)
+      source_list_for(source).find {|s| s.include?(source) }
+    end
+
+    def lock_sources
+      lock_other_sources + lock_rubygems_sources
+    end
+
+    def lock_other_sources
+      (path_sources + git_sources + plugin_sources).sort_by(&:identifier)
+    end
+
+    def lock_rubygems_sources
+      rubygems_sources.sort_by(&:identifier)
+    end
+
+    # Returns true if there are changes
+    def replace_sources!(replacement_sources)
+      return false if replacement_sources.empty?
+
+      @rubygems_sources, @path_sources, @git_sources, @plugin_sources = map_sources(replacement_sources)
+      @global_rubygems_source = global_replacement_source(replacement_sources)
+
+      !equivalent_sources?(lock_sources, replacement_sources)
+    end
+
+    def prefer_local!
+      all_sources.each(&:prefer_local!)
+    end
+
+    def local_only!
+      all_sources.each(&:local_only!)
+    end
+
+    def local!
+      all_sources.each(&:local!)
+    end
+
+    def cached!
+      all_sources.each(&:cached!)
+    end
+
+    def remote!
+      @local_mode = false
+
+      all_sources.each(&:remote!)
+    end
+
+    def clear_cache
+      rubygems_sources.each(&:clear_cache)
+    end
+
+    private
+
+    def map_sources(replacement_sources)
+      rubygems = @rubygems_sources.map do |source|
+        replace_rubygems_source(replacement_sources, source)
+      end
+
+      git, plugin = [@git_sources, @plugin_sources].map do |sources|
+        sources.map do |source|
+          replace_source(replacement_sources, source)
+        end
+      end
+
+      path = @path_sources.map do |source|
+        replace_path_source(replacement_sources, source)
+      end
+
+      [rubygems, path, git, plugin]
+    end
+
+    def global_replacement_source(replacement_sources)
+      replace_rubygems_source(replacement_sources, global_rubygems_source, &:local!)
+    end
+
+    def replace_rubygems_source(replacement_sources, gemfile_source)
+      replace_source(replacement_sources, gemfile_source) do |replacement_source|
+        # locked sources never include credentials so always prefer remotes from the gemfile
+        replacement_source.remotes = gemfile_source.remotes
+
+        yield replacement_source if block_given?
+
+        replacement_source
+      end
+    end
+
+    def replace_source(replacement_sources, gemfile_source)
+      replacement_source = replacement_sources.find {|s| s == gemfile_source }
+      return gemfile_source unless replacement_source
+
+      replacement_source = yield(replacement_source) if block_given?
+
+      replacement_source
+    end
+
+    def replace_path_source(replacement_sources, gemfile_source)
+      replace_source(replacement_sources, gemfile_source) do |replacement_source|
+        if gemfile_source.is_a?(Source::Gemspec)
+          gemfile_source.checksum_store = replacement_source.checksum_store
+          gemfile_source
+        else
+          replacement_source
+        end
+      end
+    end
+
+    def source_class
+      Source::Rubygems
+    end
+
+    def add_source_to_list(source, list)
+      list.unshift(source).uniq!
+      source
+    end
+
+    def source_list_for(source)
+      case source
+      when Source::Git          then git_sources
+      when Source::Path         then path_sources
+      when Source::Rubygems     then rubygems_sources
+      when Plugin::API::Source  then plugin_sources
+      else raise ArgumentError, "Invalid source: #{source.inspect}"
+      end
+    end
+
+    def warn_on_git_protocol(source)
+      return if Bundler.settings["git.allow_insecure"]
+
+      if /^git\:/.match?(source.uri)
+        Bundler.ui.warn "The git source `#{source.uri}` uses the `git` protocol, " \
+          "which transmits data without encryption. Disable this warning with " \
+          "`bundle config set --local git.allow_insecure true`, or switch to the `https` " \
+          "protocol to keep your data secure."
+      end
+    end
+
+    def equivalent_sources?(lock_sources, replacement_sources)
+      lock_sources.sort_by(&:identifier) == replacement_sources.sort_by(&:identifier)
+    end
+  end
+end
diff --git a/lib/bundler/source_map.rb b/lib/bundler/source_map.rb
new file mode 100644
index 0000000000..513eb37f8b
--- /dev/null
+++ b/lib/bundler/source_map.rb
@@ -0,0 +1,72 @@
+# frozen_string_literal: true
+
+module Bundler
+  class SourceMap
+    attr_reader :sources, :dependencies, :locked_specs
+
+    def initialize(sources, dependencies, locked_specs)
+      @sources = sources
+      @dependencies = dependencies
+      @locked_specs = locked_specs
+    end
+
+    def pinned_spec_names(skip = nil)
+      direct_requirements.reject {|_, source| source == skip }.keys
+    end
+
+    def all_requirements(excluded_sources = [])
+      requirements = direct_requirements.dup
+
+      explicit_sources = sources.non_default_explicit_sources.reject do |source|
+        excluded_sources.include?(source)
+      end
+
+      unmet_deps = explicit_sources.map do |source|
+        (source.spec_names - pinned_spec_names).each do |indirect_dependency_name|
+          previous_source = requirements[indirect_dependency_name]
+          if previous_source.nil?
+            requirements[indirect_dependency_name] = source
+          else
+            msg = ["The gem '#{indirect_dependency_name}' was found in multiple relevant sources."]
+            msg.concat [previous_source, source].map {|s| "  * #{s}" }.sort
+            msg << "You must add this gem to the source block for the source you wish it to be installed from."
+            msg = msg.join("\n")
+
+            raise SecurityError, msg
+          end
+        end
+
+        source.unmet_deps
+      end
+
+      sources.default_source.add_dependency_names(unmet_deps.flatten - requirements.keys)
+
+      requirements
+    end
+
+    def direct_requirements
+      @direct_requirements ||= begin
+        requirements = {}
+        default = sources.default_source
+        dependencies.each do |dep|
+          dep_source = dep.source || default
+          dep_source.add_dependency_names(dep.name)
+          requirements[dep.name] = dep_source
+        end
+        requirements
+      end
+    end
+
+    def locked_requirements
+      @locked_requirements ||= begin
+        requirements = {}
+        locked_specs.each do |locked_spec|
+          source = locked_spec.source
+          source.add_dependency_names(locked_spec.name)
+          requirements[locked_spec.name] = source
+        end
+        requirements
+      end
+    end
+  end
+end
diff --git a/lib/bundler/spec_set.rb b/lib/bundler/spec_set.rb
new file mode 100644
index 0000000000..ae5e5cbaa9
--- /dev/null
+++ b/lib/bundler/spec_set.rb
@@ -0,0 +1,402 @@
+# frozen_string_literal: true
+
+require_relative "vendored_tsort"
+
+module Bundler
+  class SpecSet
+    include Enumerable
+    include TSort
+
+    def initialize(specs)
+      @specs = specs
+    end
+
+    def for(dependencies, platforms = [nil], legacy_platforms = [nil], skips: [])
+      if [true, false].include?(platforms)
+        Bundler::SharedHelpers.feature_removed! \
+          "SpecSet#for received a `check` parameter, but that's no longer used and deprecated. " \
+          "SpecSet#for always implicitly performs validation. Please remove this parameter"
+      end
+
+      materialize_dependencies(dependencies, platforms, skips: skips)
+
+      @materializations.flat_map(&:specs).uniq
+    end
+
+    def normalize_platforms!(deps, platforms)
+      remove_invalid_platforms!(deps, platforms)
+      add_extra_platforms!(platforms)
+
+      platforms.map! do |platform|
+        next platform if platform == Gem::Platform::RUBY
+
+        begin
+          Integer(platform.version)
+        rescue ArgumentError, TypeError
+          next platform
+        end
+
+        less_specific_platform = Gem::Platform.new([platform.cpu, platform.os, nil])
+        next platform if incomplete_for_platform?(deps, less_specific_platform)
+
+        less_specific_platform
+      end.uniq!
+    end
+
+    def add_originally_invalid_platforms!(platforms, originally_invalid_platforms)
+      originally_invalid_platforms.each do |originally_invalid_platform|
+        platforms << originally_invalid_platform if complete_platform(originally_invalid_platform)
+      end
+    end
+
+    def remove_invalid_platforms!(deps, platforms, skips: [])
+      invalid_platforms = []
+
+      platforms.reject! do |platform|
+        next false if skips.include?(platform)
+
+        invalid = incomplete_for_platform?(deps, platform)
+        invalid_platforms << platform if invalid
+        invalid
+      end
+
+      invalid_platforms
+    end
+
+    def add_extra_platforms!(platforms)
+      if @specs.empty?
+        platforms.concat([Gem::Platform::RUBY]).uniq
+        return
+      end
+
+      new_platforms = all_platforms.select do |platform|
+        next if platforms.include?(platform)
+        next unless Gem::Platform.generic(platform) == Gem::Platform::RUBY
+
+        complete_platform(platform)
+      end
+      return if new_platforms.empty?
+
+      platforms.concat(new_platforms)
+      return if new_platforms.include?(Bundler.local_platform)
+
+      less_specific_platform = new_platforms.find {|platform| platform != Gem::Platform::RUBY && Bundler.local_platform === platform && platform === Bundler.local_platform }
+      platforms.delete(Bundler.local_platform) if less_specific_platform
+    end
+
+    def validate_deps(s)
+      s.runtime_dependencies.each do |dep|
+        next if dep.name == "bundler"
+
+        return :missing unless names.include?(dep.name)
+        return :invalid if none? {|spec| dep.matches_spec?(spec) }
+      end
+
+      :valid
+    end
+
+    def [](key)
+      key = key.name if key.respond_to?(:name)
+      lookup[key]&.reverse || []
+    end
+
+    def []=(key, value)
+      delete_by_name(key)
+
+      add_spec(value)
+    end
+
+    def delete(specs)
+      Array(specs).each {|spec| remove_spec(spec) }
+    end
+
+    def sort!
+      self
+    end
+
+    def to_a
+      sorted.dup
+    end
+
+    def to_hash
+      lookup.dup
+    end
+
+    def materialize(deps)
+      materialize_dependencies(deps)
+
+      SpecSet.new(materialized_specs)
+    end
+
+    # Materialize for all the specs in the spec set, regardless of what platform they're for
+    # @return [Array<Gem::Specification>]
+    def materialized_for_all_platforms
+      @specs.map do |s|
+        next s unless s.is_a?(LazySpecification)
+        spec = s.materialize_for_cache
+        raise GemNotFound, "Could not find #{s.full_name} in any of the sources" unless spec
+        spec
+      end
+    end
+
+    def incomplete_for_platform?(deps, platform)
+      incomplete_specs_for_platform(deps, platform).any?
+    end
+
+    def incomplete_specs_for_platform(deps, platform)
+      return [] if @specs.empty?
+
+      validation_set = self.class.new(@specs)
+      validation_set.for(deps, [platform])
+      validation_set.incomplete_specs
+    end
+
+    def missing_specs_for(deps)
+      materialize_dependencies(deps)
+
+      missing_specs
+    end
+
+    def missing_specs
+      @materializations.flat_map(&:completely_missing_specs)
+    end
+
+    def partially_missing_specs
+      @materializations.flat_map(&:partially_missing_specs)
+    end
+
+    def incomplete_specs
+      @materializations.flat_map(&:incomplete_specs)
+    end
+
+    def insecurely_materialized_specs
+      materialized_specs.select(&:insecurely_materialized?)
+    end
+
+    def -(other)
+      SharedHelpers.feature_removed! "SpecSet#- has been removed with no replacement"
+    end
+
+    def find_by_name_and_platform(name, platform)
+      lookup[name]&.detect {|spec| spec.installable_on_platform?(platform) }
+    end
+
+    def specs_with_additional_variants_from(other)
+      sorted | additional_variants_from(other)
+    end
+
+    def delete_by_name(name)
+      @specs.reject! {|spec| spec.name == name }
+      @sorted&.reject! {|spec| spec.name == name }
+      return if @lookup.nil?
+
+      @lookup[name] = nil
+    end
+
+    def version_for(name)
+      exemplary_spec(name)&.version
+    end
+
+    def what_required(spec)
+      unless req = find {|s| s.runtime_dependencies.any? {|d| d.name == spec.name } }
+        return [spec]
+      end
+      what_required(req) << spec
+    end
+
+    def <<(spec)
+      SharedHelpers.feature_removed! "SpecSet#<< has been removed with no replacement"
+    end
+
+    def length
+      @specs.length
+    end
+
+    def size
+      @specs.size
+    end
+
+    def empty?
+      @specs.empty?
+    end
+
+    def each(&b)
+      sorted.each(&b)
+    end
+
+    def names
+      lookup.keys
+    end
+
+    def valid?(s)
+      s.matches_current_metadata? && valid_dependencies?(s)
+    end
+
+    def to_s
+      map(&:full_name).to_s
+    end
+
+    private
+
+    def materialize_dependencies(dependencies, platforms = [nil], skips: [])
+      handled = ["bundler"].product(platforms).map {|k| [k, true] }.to_h
+      deps = dependencies.product(platforms)
+      @materializations = []
+
+      loop do
+        break unless dep = deps.shift
+
+        dependency = dep[0]
+        platform = dep[1]
+        name = dependency.name
+
+        key = [name, platform]
+        next if handled.key?(key)
+
+        handled[key] = true
+
+        materialization = Materialization.new(dependency, platform, candidates: lookup[name])
+
+        deps.concat(materialization.dependencies) if materialization.complete?
+
+        @materializations << materialization unless skips.include?(name)
+      end
+
+      @materializations
+    end
+
+    def materialized_specs
+      @materializations.filter_map(&:materialized_spec)
+    end
+
+    def complete_platform(platform)
+      new_specs = []
+
+      valid_platform = lookup.all? do |_, specs|
+        spec = specs.first
+        # The matching candidates returned by source.specs.search are remote
+        # specs that do not carry the override list themselves. Borrow it from
+        # the LazySpec we are validating so platform-variant validation honors
+        # the same overrides the install/resolve path already applies.
+        overrides = spec.is_a?(LazySpecification) ? Array(spec.overrides) : []
+        matching_specs = spec.source.specs.search([spec.name, spec.version])
+        platform_spec = MatchPlatform.select_best_platform_match(matching_specs, platform).find do |s|
+          s.matches_current_metadata_with_overrides?(overrides) && valid_dependencies?(s)
+        end
+
+        if platform_spec
+          unless specs.include?(platform_spec)
+            new_lazy = LazySpecification.from_spec(platform_spec)
+            # Carry the overrides forward so a follow-up complete_platform
+            # call that picks this synthesized variant as its exemplar still
+            # honors the user's override list.
+            new_lazy.overrides = overrides if overrides.any?
+            new_specs << new_lazy
+          end
+          true
+        else
+          false
+        end
+      end
+
+      if valid_platform && new_specs.any?
+        new_specs.each {|spec| add_spec(spec) }
+      end
+
+      valid_platform
+    end
+
+    def all_platforms
+      @specs.flat_map {|spec| spec.source.specs.search([spec.name, spec.version]).map(&:platform) }.uniq
+    end
+
+    def additional_variants_from(other)
+      other.select do |other_spec|
+        spec = exemplary_spec(other_spec.name)
+        next unless spec
+
+        selected = spec.version == other_spec.version && valid_dependencies?(other_spec)
+        other_spec.source = spec.source if selected
+        selected
+      end
+    end
+
+    def valid_dependencies?(s)
+      validate_deps(s) == :valid
+    end
+
+    def sorted
+      @sorted ||= ([lookup["rake"]&.first] + tsort).compact.uniq
+    rescue TSort::Cyclic => error
+      cgems = extract_circular_gems(error)
+      raise CyclicDependencyError, "Your bundle requires gems that depend" \
+        " on each other, creating an infinite loop. Please remove either" \
+        " gem '#{cgems[0]}' or gem '#{cgems[1]}' and try again."
+    end
+
+    def extract_circular_gems(error)
+      error.message.scan(/@name="(.*?)"/).flatten
+    end
+
+    def lookup
+      @lookup ||= begin
+        lookup = {}
+        @specs.each do |s|
+          index_spec(lookup, s.name, s)
+        end
+        lookup
+      end
+    end
+
+    def tsort_each_node
+      # MUST sort by name for backwards compatibility
+      @specs.sort_by(&:name).each {|s| yield s }
+    end
+
+    def tsort_each_child(s)
+      s.dependencies.sort_by(&:name).each do |d|
+        next if d.type == :development
+
+        specs_for_name = lookup[d.name]
+        next unless specs_for_name
+
+        specs_for_name.each {|s2| yield s2 }
+      end
+    end
+
+    def add_spec(spec)
+      @specs << spec
+
+      name = spec.name
+
+      @sorted&.insert(@sorted.bsearch_index {|s| s.name >= name } || @sorted.size, spec)
+      return if @lookup.nil?
+
+      index_spec(@lookup, name, spec)
+    end
+
+    def remove_spec(spec)
+      @specs.delete(spec)
+      @sorted&.delete(spec)
+      return if @lookup.nil?
+
+      indexed_specs = @lookup[spec.name]
+      return unless indexed_specs
+
+      if indexed_specs.size > 1
+        @lookup[spec.name].delete(spec)
+      else
+        @lookup[spec.name] = nil
+      end
+    end
+
+    def index_spec(hash, key, value)
+      hash[key] ||= []
+      hash[key] << value
+    end
+
+    def exemplary_spec(name)
+      self[name].first
+    end
+  end
+end
diff --git a/lib/bundler/stub_specification.rb b/lib/bundler/stub_specification.rb
new file mode 100644
index 0000000000..b353642b40
--- /dev/null
+++ b/lib/bundler/stub_specification.rb
@@ -0,0 +1,147 @@
+# frozen_string_literal: true
+
+module Bundler
+  class StubSpecification < RemoteSpecification
+    def self.from_stub(stub)
+      return stub if stub.is_a?(Bundler::StubSpecification)
+      spec = new(stub.name, stub.version, stub.platform, nil)
+      spec.stub = stub
+      spec
+    end
+
+    def insecurely_materialized?
+      false
+    end
+
+    attr_reader :checksum
+    attr_accessor :stub, :ignored
+
+    def source=(source)
+      super
+      # Stub has no concept of source, which means that extension_dir may be wrong
+      # This is the case for git-based gems. So, instead manually assign the extension dir
+      return unless source.respond_to?(:extension_dir_name)
+      unique_extension_dir = [source.extension_dir_name, File.basename(full_gem_path)].uniq.join("-")
+      path = File.join(stub.extensions_dir, unique_extension_dir)
+      stub.extension_dir = File.expand_path(path)
+    end
+
+    def to_yaml
+      _remote_specification.to_yaml
+    end
+
+    # @!group Stub Delegates
+
+    def ignored?
+      return @ignored unless @ignored.nil?
+
+      @ignored = missing_extensions?
+      return false unless @ignored
+
+      warn "Source #{source} is ignoring #{self} because it is missing extensions"
+
+      true
+    end
+
+    def manually_installed?
+      # This is for manually installed gems which are gems that were fixed in place after a
+      # failed installation. Once the issue was resolved, the user then manually created
+      # the gem specification using the instructions provided by `gem help install`
+      installed_by_version == Gem::Version.new(0)
+    end
+
+    # This is defined directly to avoid having to loading the full spec
+    def missing_extensions?
+      return false if RUBY_ENGINE == "jruby"
+      return false if default_gem?
+      return false if extensions.empty?
+      return false if File.exist? gem_build_complete_path
+      return false if manually_installed?
+
+      true
+    end
+
+    def activated?
+      stub.activated?
+    end
+
+    def activated=(activated)
+      stub.instance_variable_set(:@activated, activated)
+    end
+
+    def extensions
+      stub.extensions
+    end
+
+    def gem_build_complete_path
+      stub.gem_build_complete_path
+    end
+
+    def default_gem?
+      stub.default_gem?
+    end
+
+    def full_gem_path
+      stub.full_gem_path
+    end
+
+    def full_gem_path=(path)
+      stub.full_gem_path = path
+    end
+
+    def full_require_paths
+      stub.full_require_paths
+    end
+
+    def require_paths
+      stub.require_paths
+    end
+
+    def base_dir=(path)
+      stub.base_dir = path
+    end
+
+    def load_paths
+      full_require_paths
+    end
+
+    def loaded_from
+      stub.loaded_from
+    end
+
+    def matches_for_glob(glob)
+      stub.matches_for_glob(glob)
+    end
+
+    def raw_require_paths
+      stub.raw_require_paths
+    end
+
+    def inspect
+      "#<#{self.class} @name=\"#{name}\" (#{full_name.delete_prefix("#{name}-")})>"
+    end
+
+    private
+
+    def _remote_specification
+      @_remote_specification ||= begin
+        rs = stub.to_spec
+        if rs.equal?(self) # happens when to_spec gets the spec from Gem.loaded_specs
+          rs = Gem::Specification.load(loaded_from)
+          Bundler.rubygems.stub_set_spec(stub, rs)
+        end
+
+        unless rs
+          raise GemspecError, "The gemspec for #{full_name} at #{loaded_from}" \
+            " was missing or broken. Try running `gem pristine #{name} -v #{version}`" \
+            " to fix the cached spec."
+        end
+
+        rs.source = source
+        rs.base_dir = stub.base_dir
+
+        rs
+      end
+    end
+  end
+end
diff --git a/lib/bundler/templates/.document b/lib/bundler/templates/.document
new file mode 100644
index 0000000000..fb66f13c33
--- /dev/null
+++ b/lib/bundler/templates/.document
@@ -0,0 +1 @@
+# Ignore all files in this directory
diff --git a/lib/bundler/templates/Executable b/lib/bundler/templates/Executable
new file mode 100644
index 0000000000..b085c24da6
--- /dev/null
+++ b/lib/bundler/templates/Executable
@@ -0,0 +1,16 @@
+#!/usr/bin/env <%= Bundler.settings[:shebang] || RbConfig::CONFIG["ruby_install_name"] %>
+# frozen_string_literal: true
+
+#
+# This file was generated by Bundler.
+#
+# The application '<%= executable %>' is installed as part of a gem, and
+# this file is here to facilitate running it.
+#
+
+ENV["BUNDLE_GEMFILE"] ||= File.expand_path("<%= relative_gemfile_path %>", __dir__)
+
+require "rubygems"
+require "bundler/setup"
+
+load Gem.bin_path("<%= spec.name %>", "<%= executable %>")
diff --git a/lib/bundler/templates/Executable.standalone b/lib/bundler/templates/Executable.standalone
new file mode 100644
index 0000000000..3117a27e86
--- /dev/null
+++ b/lib/bundler/templates/Executable.standalone
@@ -0,0 +1,14 @@
+#!/usr/bin/env <%= Bundler.settings[:shebang] || RbConfig::CONFIG["ruby_install_name"] %>
+# frozen_string_literal: true
+
+#
+# This file was generated by Bundler.
+#
+# The application '<%= executable %>' is installed as part of a gem, and
+# this file is here to facilitate running it.
+#
+
+$:.unshift File.expand_path "<%= standalone_path %>", __dir__
+
+require "bundler/setup"
+load File.expand_path "<%= executable_path %>", __dir__
diff --git a/lib/bundler/templates/Gemfile b/lib/bundler/templates/Gemfile
new file mode 100644
index 0000000000..d2403f18b2
--- /dev/null
+++ b/lib/bundler/templates/Gemfile
@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+source "https://rubygems.org"
+
+# gem "rails"
diff --git a/lib/bundler/templates/newgem/CHANGELOG.md.tt b/lib/bundler/templates/newgem/CHANGELOG.md.tt
new file mode 100644
index 0000000000..c9ea96d453
--- /dev/null
+++ b/lib/bundler/templates/newgem/CHANGELOG.md.tt
@@ -0,0 +1,5 @@
+## [Unreleased]
+
+## [0.1.0] - <%= Time.now.strftime('%F') %>
+
+- Initial release
diff --git a/lib/bundler/templates/newgem/CODE_OF_CONDUCT.md.tt b/lib/bundler/templates/newgem/CODE_OF_CONDUCT.md.tt
new file mode 100644
index 0000000000..633baebdd5
--- /dev/null
+++ b/lib/bundler/templates/newgem/CODE_OF_CONDUCT.md.tt
@@ -0,0 +1,10 @@
+# Code of Conduct
+
+<%= config[:name].inspect %> follows [The Ruby Community Conduct Guideline](https://www.ruby-lang.org/en/conduct) in all "collaborative space", which is defined as community communications channels (such as mailing lists, submitted patches, commit comments, etc.):
+
+* Participants will be tolerant of opposing views.
+* Participants must ensure that their language and actions are free of personal attacks and disparaging personal remarks.
+* When interpreting the words and actions of others, participants should always assume good intentions.
+* Behaviour which can be reasonably considered harassment will not be tolerated.
+
+If you have any concerns about behaviour within this project, please contact us at [<%= config[:email].inspect %>](mailto:<%= config[:email].inspect %>).
diff --git a/lib/bundler/templates/newgem/Cargo.toml.tt b/lib/bundler/templates/newgem/Cargo.toml.tt
new file mode 100644
index 0000000000..cd00f97e5a
--- /dev/null
+++ b/lib/bundler/templates/newgem/Cargo.toml.tt
@@ -0,0 +1,13 @@
+# This Cargo.toml is here to let externals tools (IDEs, etc.) know that this is
+# a Rust project. Your extensions dependencies should be added to the Cargo.toml
+# in the ext/ directory.
+
+[workspace]
+members = ["./ext/<%= config[:name] %>"]
+resolver = "2"
+
+[profile.release]
+# By default, debug symbols are stripped from the final binary which makes it
+# harder to debug if something goes wrong. It's recommended to keep debug
+# symbols in the release build so that you can debug the final binary if needed.
+debug = true
diff --git a/lib/bundler/templates/newgem/Gemfile.tt b/lib/bundler/templates/newgem/Gemfile.tt
new file mode 100644
index 0000000000..85dc593b8f
--- /dev/null
+++ b/lib/bundler/templates/newgem/Gemfile.tt
@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+source "https://rubygems.org"
+
+# Specify your gem's dependencies in <%= config[:name] %>.gemspec
+gemspec
+
+gem "irb"
+gem "rake", ">= 13.0"
+<%- if config[:ext] -%>
+
+gem "rake-compiler"
+<%- end -%>
+<%- if config[:test] -%>
+
+gem "<%= config[:test] %>"
+<%- end -%>
+<%- if config[:linter] == "rubocop" -%>
+
+gem "rubocop"
+<%- elsif config[:linter] == "standard" -%>
+
+gem "standard"
+<%- end -%>
diff --git a/lib/bundler/templates/newgem/LICENSE.txt.tt b/lib/bundler/templates/newgem/LICENSE.txt.tt
new file mode 100644
index 0000000000..76ef4b0191
--- /dev/null
+++ b/lib/bundler/templates/newgem/LICENSE.txt.tt
@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) <%= Time.now.year %> <%= config[:author] %>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
diff --git a/lib/bundler/templates/newgem/README.md.tt b/lib/bundler/templates/newgem/README.md.tt
new file mode 100644
index 0000000000..0ec6a12fa7
--- /dev/null
+++ b/lib/bundler/templates/newgem/README.md.tt
@@ -0,0 +1,49 @@
+# <%= config[:constant_name] %>
+
+TODO: Delete this and the text below, and describe your gem
+
+Welcome to your new gem! In this directory, you'll find the files you need to be able to package up your Ruby library into a gem. Put your Ruby code in the file `lib/<%= config[:namespaced_path] %>`. To experiment with that code, run `bin/console` for an interactive prompt.
+
+## Installation
+
+TODO: Replace `UPDATE_WITH_YOUR_GEM_NAME_IMMEDIATELY_AFTER_RELEASE_TO_RUBYGEMS_ORG` with your gem name right after releasing it to RubyGems.org. Please do not do it earlier due to security reasons. Alternatively, replace this section with instructions to install your gem from git if you don't plan to release to RubyGems.org.
+
+Install the gem and add to the application's Gemfile by executing:
+
+```bash
+bundle add UPDATE_WITH_YOUR_GEM_NAME_IMMEDIATELY_AFTER_RELEASE_TO_RUBYGEMS_ORG
+```
+
+If bundler is not being used to manage dependencies, install the gem by executing:
+
+```bash
+gem install UPDATE_WITH_YOUR_GEM_NAME_IMMEDIATELY_AFTER_RELEASE_TO_RUBYGEMS_ORG
+```
+
+## Usage
+
+TODO: Write usage instructions here
+
+## Development
+
+After checking out the repo, run `bin/setup` to install dependencies.<% if config[:test] %> Then, run `rake <%= config[:test_task] %>` to run the tests.<% end %> You can also run `bin/console` for an interactive prompt that will allow you to experiment.<% if config[:bin] %> Run `bundle exec <%= config[:name] %>` to use the gem in this directory, ignoring other installed copies of this gem.<% end %>
+
+To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and the created tag, and push the `.gem` file to [rubygems.org](https://rubygems.org).
+<% if config[:git] -%>
+
+## Contributing
+
+Bug reports and pull requests are welcome on GitHub at https://github.com/<%= config[:github_username] %>/<%= config[:name] %>.<% if config[:coc] %> This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the [code of conduct](https://github.com/<%= config[:github_username] %>/<%= config[:name] %>/blob/<%= config[:git_default_branch] %>/CODE_OF_CONDUCT.md).<% end %>
+<% end -%>
+<% if config[:mit] -%>
+
+## License
+
+The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).
+<% end -%>
+<% if config[:git] && config[:coc] -%>
+
+## Code of Conduct
+
+Everyone interacting in the <%= config[:constant_name] %> project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the [code of conduct](https://github.com/<%= config[:github_username] %>/<%= config[:name] %>/blob/<%= config[:git_default_branch] %>/CODE_OF_CONDUCT.md).
+<% end -%>
diff --git a/lib/bundler/templates/newgem/Rakefile.tt b/lib/bundler/templates/newgem/Rakefile.tt
new file mode 100644
index 0000000000..83f10009c7
--- /dev/null
+++ b/lib/bundler/templates/newgem/Rakefile.tt
@@ -0,0 +1,72 @@
+# frozen_string_literal: true
+
+require "bundler/gem_tasks"
+<% default_task_names = [config[:test_task]].compact -%>
+<% case config[:test] -%>
+<% when "minitest" -%>
+require "minitest/test_task"
+
+Minitest::TestTask.create
+
+<% when "test-unit" -%>
+require "rake/testtask"
+
+Rake::TestTask.new(:test) do |t|
+  t.libs << "test"
+  t.libs << "lib"
+  t.test_files = FileList["test/**/*_test.rb"]
+end
+
+<% when "rspec" -%>
+require "rspec/core/rake_task"
+
+RSpec::Core::RakeTask.new(:spec)
+
+<% end -%>
+<% if config[:linter] == "rubocop" -%>
+<% default_task_names << :rubocop -%>
+require "rubocop/rake_task"
+
+RuboCop::RakeTask.new
+
+<% elsif config[:linter] == "standard" -%>
+<% default_task_names << :standard -%>
+require "standard/rake"
+
+<% end -%>
+<% if config[:ext] -%>
+<% default_task_names.unshift(:compile) -%>
+<% default_task_names.unshift(:clobber) unless config[:ext] == 'rust' -%>
+<% if config[:ext] == 'rust' -%>
+require "rb_sys/extensiontask"
+
+task build: :compile
+
+GEMSPEC = Gem::Specification.load("<%= config[:underscored_name] %>.gemspec")
+
+RbSys::ExtensionTask.new(<%= config[:name].inspect %>, GEMSPEC) do |ext|
+  ext.lib_dir = "lib/<%= config[:namespaced_path] %>"
+end
+<% else -%>
+require "rake/extensiontask"
+
+task build: :compile
+
+GEMSPEC = Gem::Specification.load("<%= config[:underscored_name] %>.gemspec")
+
+Rake::ExtensionTask.new("<%= config[:underscored_name] %>", GEMSPEC) do |ext|
+  ext.lib_dir = "lib/<%= config[:namespaced_path] %>"
+end
+<% end -%>
+
+<% if config[:ext] == "go" -%>
+require "go_gem/rake_task"
+
+GoGem::RakeTask.new("<%= config[:underscored_name] %>")
+<% end -%>
+<% end -%>
+<% if default_task_names.size == 1 -%>
+task default: <%= default_task_names.first.inspect %>
+<% else -%>
+task default: %i[<%= default_task_names.join(" ") %>]
+<% end -%>
diff --git a/lib/bundler/templates/newgem/bin/console.tt b/lib/bundler/templates/newgem/bin/console.tt
new file mode 100644
index 0000000000..c91ee65f93
--- /dev/null
+++ b/lib/bundler/templates/newgem/bin/console.tt
@@ -0,0 +1,11 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require "bundler/setup"
+require "<%= config[:namespaced_path] %>"
+
+# You can add fixtures and/or initialization code here to make experimenting
+# with your gem easier. You can also use a different console, if you like.
+
+require "irb"
+IRB.start(__FILE__)
diff --git a/lib/bundler/templates/newgem/bin/setup.tt b/lib/bundler/templates/newgem/bin/setup.tt
new file mode 100644
index 0000000000..dce67d860a
--- /dev/null
+++ b/lib/bundler/templates/newgem/bin/setup.tt
@@ -0,0 +1,8 @@
+#!/usr/bin/env bash
+set -euo pipefail
+IFS=$'\n\t'
+set -vx
+
+bundle install
+
+# Do any other automated setup that you need to do here
diff --git a/lib/bundler/templates/newgem/circleci/config.yml.tt b/lib/bundler/templates/newgem/circleci/config.yml.tt
new file mode 100644
index 0000000000..c4dd9d0647
--- /dev/null
+++ b/lib/bundler/templates/newgem/circleci/config.yml.tt
@@ -0,0 +1,37 @@
+version: 2.1
+jobs:
+  build:
+    docker:
+      - image: ruby:<%= RUBY_VERSION %>
+<%- if config[:ext] == 'rust' -%>
+    environment:
+      RB_SYS_FORCE_INSTALL_RUST_TOOLCHAIN: 'true'
+<%- end -%>
+<%- if config[:ext] == 'go' -%>
+    environment:
+      GO_VERSION: '1.23.0'
+<%- end -%>
+    steps:
+      - checkout
+<%- if config[:ext] == 'rust' -%>
+      - run:
+          name: Install Rust/Cargo dependencies
+          command: apt-get update && apt-get install -y clang
+      - run:
+          name: Install a RubyGems version that can compile rust extensions
+          command: gem update --system '<%= ::Gem.rubygems_version %>'
+<%- end -%>
+<%- if config[:ext] == 'go' -%>
+      - run:
+          name: Install Go
+          command: |
+            wget https://go.dev/dl/go$GO_VERSION.linux-amd64.tar.gz -O /tmp/go.tar.gz
+            tar -C /usr/local -xzf /tmp/go.tar.gz
+            echo 'export PATH=/usr/local/go/bin:"$PATH"' >> "$BASH_ENV"
+<%- end -%>
+      - run:
+          name: Run the default task
+          command: |
+            gem install bundler -v <%= Bundler::VERSION %>
+            bundle install
+            bundle exec rake
diff --git a/lib/bundler/templates/newgem/exe/newgem.tt b/lib/bundler/templates/newgem/exe/newgem.tt
new file mode 100644
index 0000000000..a8339bb79f
--- /dev/null
+++ b/lib/bundler/templates/newgem/exe/newgem.tt
@@ -0,0 +1,3 @@
+#!/usr/bin/env ruby
+
+require "<%= config[:namespaced_path] %>"
diff --git a/lib/bundler/templates/newgem/ext/newgem/Cargo.toml.tt b/lib/bundler/templates/newgem/ext/newgem/Cargo.toml.tt
new file mode 100644
index 0000000000..a06166aee7
--- /dev/null
+++ b/lib/bundler/templates/newgem/ext/newgem/Cargo.toml.tt
@@ -0,0 +1,22 @@
+[package]
+name = <%= config[:name].inspect %>
+version = "0.1.0"
+edition = "2021"
+authors = ["<%= config[:author] %> <<%= config[:email] %>>"]
+<%- if config[:mit] -%>
+license = "MIT"
+<%- end -%>
+publish = false
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+magnus = { version = "0.8.2" }
+rb-sys = { version = "0.9", features = ["stable-api-compiled-fallback"] }
+
+[build-dependencies]
+rb-sys-env = "0.2.2"
+
+[dev-dependencies]
+rb-sys-test-helpers = { version = "0.2.2" }
diff --git a/lib/bundler/templates/newgem/ext/newgem/build.rs.tt b/lib/bundler/templates/newgem/ext/newgem/build.rs.tt
new file mode 100644
index 0000000000..80a7842753
--- /dev/null
+++ b/lib/bundler/templates/newgem/ext/newgem/build.rs.tt
@@ -0,0 +1,5 @@
+pub fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let _ = rb_sys_env::activate()?;
+
+    Ok(())
+}
diff --git a/lib/bundler/templates/newgem/ext/newgem/extconf-c.rb.tt b/lib/bundler/templates/newgem/ext/newgem/extconf-c.rb.tt
new file mode 100644
index 0000000000..0a0c5a3d09
--- /dev/null
+++ b/lib/bundler/templates/newgem/ext/newgem/extconf-c.rb.tt
@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+require "mkmf"
+
+# Makes all symbols private by default to avoid unintended conflict
+# with other gems. To explicitly export symbols you can use RUBY_FUNC_EXPORTED
+# selectively, or entirely remove this flag.
+append_cflags("-fvisibility=hidden")
+
+create_makefile(<%= config[:makefile_path].inspect %>)
diff --git a/lib/bundler/templates/newgem/ext/newgem/extconf-go.rb.tt b/lib/bundler/templates/newgem/ext/newgem/extconf-go.rb.tt
new file mode 100644
index 0000000000..a689e21ebe
--- /dev/null
+++ b/lib/bundler/templates/newgem/ext/newgem/extconf-go.rb.tt
@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+require "mkmf"
+require "go_gem/mkmf"
+
+# Makes all symbols private by default to avoid unintended conflict
+# with other gems. To explicitly export symbols you can use RUBY_FUNC_EXPORTED
+# selectively, or entirely remove this flag.
+append_cflags("-fvisibility=hidden")
+
+create_go_makefile(<%= config[:makefile_path].inspect %>)
diff --git a/lib/bundler/templates/newgem/ext/newgem/extconf-rust.rb.tt b/lib/bundler/templates/newgem/ext/newgem/extconf-rust.rb.tt
new file mode 100644
index 0000000000..e24566a17a
--- /dev/null
+++ b/lib/bundler/templates/newgem/ext/newgem/extconf-rust.rb.tt
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+require "mkmf"
+require "rb_sys/mkmf"
+
+create_rust_makefile(<%= config[:makefile_path].inspect %>)
diff --git a/lib/bundler/templates/newgem/ext/newgem/go.mod.tt b/lib/bundler/templates/newgem/ext/newgem/go.mod.tt
new file mode 100644
index 0000000000..3f4819d004
--- /dev/null
+++ b/lib/bundler/templates/newgem/ext/newgem/go.mod.tt
@@ -0,0 +1,5 @@
+module github.com/<%= config[:go_module_username] %>/<%= config[:underscored_name] %>
+
+go 1.23
+
+require github.com/ruby-go-gem/go-gem-wrapper latest
diff --git a/lib/bundler/templates/newgem/ext/newgem/newgem-go.c.tt b/lib/bundler/templates/newgem/ext/newgem/newgem-go.c.tt
new file mode 100644
index 0000000000..119c0c96ea
--- /dev/null
+++ b/lib/bundler/templates/newgem/ext/newgem/newgem-go.c.tt
@@ -0,0 +1,2 @@
+#include "<%= config[:underscored_name] %>.h"
+#include "_cgo_export.h"
diff --git a/lib/bundler/templates/newgem/ext/newgem/newgem.c.tt b/lib/bundler/templates/newgem/ext/newgem/newgem.c.tt
new file mode 100644
index 0000000000..bcd5148569
--- /dev/null
+++ b/lib/bundler/templates/newgem/ext/newgem/newgem.c.tt
@@ -0,0 +1,9 @@
+#include "<%= config[:underscored_name] %>.h"
+
+VALUE rb_m<%= config[:constant_array].join %>;
+
+RUBY_FUNC_EXPORTED void
+Init_<%= config[:underscored_name] %>(void)
+{
+  rb_m<%= config[:constant_array].join %> = rb_define_module(<%= config[:constant_name].inspect %>);
+}
diff --git a/lib/bundler/templates/newgem/ext/newgem/newgem.go.tt b/lib/bundler/templates/newgem/ext/newgem/newgem.go.tt
new file mode 100644
index 0000000000..f19b750e58
--- /dev/null
+++ b/lib/bundler/templates/newgem/ext/newgem/newgem.go.tt
@@ -0,0 +1,31 @@
+package main
+
+/*
+#include "<%= config[:underscored_name] %>.h"
+
+VALUE rb_<%= config[:underscored_name] %>_sum(VALUE self, VALUE a, VALUE b);
+*/
+import "C"
+
+import (
+	"github.com/ruby-go-gem/go-gem-wrapper/ruby"
+)
+
+//export rb_<%= config[:underscored_name] %>_sum
+func rb_<%= config[:underscored_name] %>_sum(_ C.VALUE, a C.VALUE, b C.VALUE) C.VALUE {
+	longA := ruby.NUM2LONG(ruby.VALUE(a))
+	longB := ruby.NUM2LONG(ruby.VALUE(b))
+
+	sum := longA + longB
+
+	return C.VALUE(ruby.LONG2NUM(sum))
+}
+
+//export Init_<%= config[:underscored_name] %>
+func Init_<%= config[:underscored_name] %>() {
+	rb_m<%= config[:constant_array].join %> := ruby.RbDefineModule(<%= config[:constant_name].inspect %>)
+	ruby.RbDefineSingletonMethod(rb_m<%= config[:constant_array].join %>, "sum", C.rb_<%= config[:underscored_name] %>_sum, 2)
+}
+
+func main() {
+}
diff --git a/lib/bundler/templates/newgem/ext/newgem/newgem.h.tt b/lib/bundler/templates/newgem/ext/newgem/newgem.h.tt
new file mode 100644
index 0000000000..c6e420b66e
--- /dev/null
+++ b/lib/bundler/templates/newgem/ext/newgem/newgem.h.tt
@@ -0,0 +1,6 @@
+#ifndef <%= config[:underscored_name].upcase %>_H
+#define <%= config[:underscored_name].upcase %>_H 1
+
+#include "ruby.h"
+
+#endif /* <%= config[:underscored_name].upcase %>_H */
diff --git a/lib/bundler/templates/newgem/ext/newgem/src/lib.rs.tt b/lib/bundler/templates/newgem/ext/newgem/src/lib.rs.tt
new file mode 100644
index 0000000000..09ce97682d
--- /dev/null
+++ b/lib/bundler/templates/newgem/ext/newgem/src/lib.rs.tt
@@ -0,0 +1,23 @@
+use magnus::{function, prelude::*, Error, Ruby};
+
+pub fn hello(subject: String) -> String {
+    format!("Hello {subject}, from Rust!")
+}
+
+#[magnus::init]
+fn init(ruby: &Ruby) -> Result<(), Error> {
+    let module = ruby.<%= config[:constant_array].map {|c| "define_module(#{c.dump})?"}.join(".") %>;
+    module.define_singleton_method("hello", function!(hello, 1))?;
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use rb_sys_test_helpers::ruby_test;
+    use super::hello;
+
+    #[ruby_test]
+    fn test_hello() {
+        assert_eq!("Hello world, from Rust!", hello("world".to_string()));
+    }
+}
diff --git a/lib/bundler/templates/newgem/github/workflows/build-gems.yml.tt b/lib/bundler/templates/newgem/github/workflows/build-gems.yml.tt
new file mode 100644
index 0000000000..d49954d2cd
--- /dev/null
+++ b/lib/bundler/templates/newgem/github/workflows/build-gems.yml.tt
@@ -0,0 +1,69 @@
+---
+name: Build gems
+
+on:
+  push:
+    tags:
+      - "v*"
+      - "cross-gem/*"
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  packages: write
+
+jobs:
+  ci-data:
+    runs-on: ubuntu-latest
+    outputs:
+      result: ${{ steps.fetch.outputs.result }}
+    steps:
+      - uses: oxidize-rb/actions/fetch-ci-data@v1
+        id: fetch
+        with:
+          supported-ruby-platforms: |
+            exclude: ["arm-linux", "x64-mingw32"]
+          stable-ruby-versions: |
+            exclude: ["head"]
+
+  source-gem:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+
+      - uses: ruby/setup-ruby@v1
+        with:
+          bundler-cache: true
+
+      - name: Build gem
+        run: bundle exec rake build
+
+      - uses: actions/upload-artifact@v7
+        with:
+          name: source-gem
+          path: pkg/*.gem
+
+  cross-gem:
+    name: Compile native gem for ${{ matrix.platform }}
+    runs-on: ubuntu-latest
+    needs: ci-data
+    strategy:
+      matrix:
+        platform: ${{ fromJSON(needs.ci-data.outputs.result).supported-ruby-platforms }}
+    steps:
+      - uses: actions/checkout@v6
+
+      - uses: ruby/setup-ruby@v1
+        with:
+          bundler-cache: true
+
+      - uses: oxidize-rb/actions/cross-gem@v1
+        id: cross-gem
+        with:
+          platform: ${{ matrix.platform }}
+          ruby-versions: ${{ join(fromJSON(needs.ci-data.outputs.result).stable-ruby-versions, ',') }}
+
+      - uses: actions/upload-artifact@v7
+        with:
+          name: cross-gem
+          path: ${{ steps.cross-gem.outputs.gem-path }}
diff --git a/lib/bundler/templates/newgem/github/workflows/main.yml.tt b/lib/bundler/templates/newgem/github/workflows/main.yml.tt
new file mode 100644
index 0000000000..cc8f04dd33
--- /dev/null
+++ b/lib/bundler/templates/newgem/github/workflows/main.yml.tt
@@ -0,0 +1,48 @@
+name: Ruby
+
+on:
+  push:
+    branches:
+      - <%= config[:git_default_branch] %>
+
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    name: Ruby ${{ matrix.ruby }}
+    strategy:
+      matrix:
+        ruby:
+          - '<%= RUBY_VERSION %>'
+
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          persist-credentials: false
+<%- if config[:ext] == 'rust' -%>
+      - name: Set up Ruby & Rust
+        uses: oxidize-rb/actions/setup-ruby-and-rust@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+          cargo-cache: true
+          rubygems: '<%= ::Gem.rubygems_version %>'
+<%- else -%>
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+<%- end -%>
+<%- if config[:ext] == 'go' -%>
+      - name: Setup Go
+        uses: actions/setup-go@v5
+        with:
+          go-version-file: ext/<%= config[:underscored_name] %>/go.mod
+<%- end -%>
+      - name: Run the default task
+        run: bundle exec rake
diff --git a/lib/bundler/templates/newgem/gitignore.tt b/lib/bundler/templates/newgem/gitignore.tt
new file mode 100644
index 0000000000..9b40ba5a58
--- /dev/null
+++ b/lib/bundler/templates/newgem/gitignore.tt
@@ -0,0 +1,23 @@
+/.bundle/
+/.yardoc
+/_yardoc/
+/coverage/
+/doc/
+/pkg/
+/spec/reports/
+/tmp/
+<%- if config[:ext] -%>
+*.bundle
+*.so
+*.o
+*.a
+mkmf.log
+<%- if config[:ext] == 'rust' -%>
+target/
+<%- end -%>
+<%- end -%>
+<%- if config[:test] == "rspec" -%>
+
+# rspec failure tracking
+.rspec_status
+<%- end -%>
diff --git a/lib/bundler/templates/newgem/gitlab-ci.yml.tt b/lib/bundler/templates/newgem/gitlab-ci.yml.tt
new file mode 100644
index 0000000000..adbd70cbc0
--- /dev/null
+++ b/lib/bundler/templates/newgem/gitlab-ci.yml.tt
@@ -0,0 +1,27 @@
+default:
+  image: ruby:<%= RUBY_VERSION %>
+
+  before_script:
+<%- if config[:ext] == 'rust' -%>
+    - apt-get update && apt-get install -y clang
+    - gem update --system '<%= ::Gem.rubygems_version %>'
+<%- end -%>
+<%- if config[:ext] == 'go' -%>
+    - wget https://go.dev/dl/go$GO_VERSION.linux-amd64.tar.gz -O /tmp/go.tar.gz
+    - tar -C /usr/local -xzf /tmp/go.tar.gz
+    - export PATH=/usr/local/go/bin:$PATH
+<%- end -%>
+    - gem install bundler -v <%= Bundler::VERSION %>
+    - bundle install
+
+example_job:
+<%- if config[:ext] == 'rust' -%>
+  variables:
+    RB_SYS_FORCE_INSTALL_RUST_TOOLCHAIN: 'true'
+<%- end -%>
+<%- if config[:ext] == 'go' -%>
+  variables:
+    GO_VERSION: '1.23.0'
+<%- end -%>
+  script:
+    - bundle exec rake
diff --git a/lib/bundler/templates/newgem/lib/newgem.rb.tt b/lib/bundler/templates/newgem/lib/newgem.rb.tt
new file mode 100644
index 0000000000..3aedee0d25
--- /dev/null
+++ b/lib/bundler/templates/newgem/lib/newgem.rb.tt
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+require_relative "<%= File.basename(config[:namespaced_path]) %>/version"
+<%- if config[:ext] -%>
+require "<%= File.basename(config[:namespaced_path]) %>/<%= config[:underscored_name] %>"
+<%- end -%>
+
+<%- config[:constant_array].each_with_index do |c, i| -%>
+<%= "  " * i %>module <%= c %>
+<%- end -%>
+<%= "  " * config[:constant_array].size %>class Error < StandardError; end
+<%= "  " * config[:constant_array].size %># Your code goes here...
+<%- (config[:constant_array].size-1).downto(0) do |i| -%>
+<%= "  " * i %>end
+<%- end -%>
diff --git a/lib/bundler/templates/newgem/lib/newgem/version.rb.tt b/lib/bundler/templates/newgem/lib/newgem/version.rb.tt
new file mode 100644
index 0000000000..b5cd4cb232
--- /dev/null
+++ b/lib/bundler/templates/newgem/lib/newgem/version.rb.tt
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+<%- config[:constant_array].each_with_index do |c, i| -%>
+<%= "  " * i %>module <%= c %>
+<%- end -%>
+<%= "  " * config[:constant_array].size %>VERSION = "0.1.0"
+<%- (config[:constant_array].size-1).downto(0) do |i| -%>
+<%= "  " * i %>end
+<%- end -%>
diff --git a/lib/bundler/templates/newgem/newgem.gemspec.tt b/lib/bundler/templates/newgem/newgem.gemspec.tt
new file mode 100644
index 0000000000..1ab1c28f46
--- /dev/null
+++ b/lib/bundler/templates/newgem/newgem.gemspec.tt
@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+require_relative "lib/<%=config[:namespaced_path]%>/version"
+
+Gem::Specification.new do |spec|
+  spec.name = <%= config[:name].inspect %>
+  spec.version = <%= config[:constant_name] %>::VERSION
+  spec.authors = [<%= config[:author].inspect %>]
+  spec.email = [<%= config[:email].inspect %>]
+
+  spec.summary = "TODO: Write a short summary, because RubyGems requires one."
+  spec.description = "TODO: Write a longer description or delete this line."
+  spec.homepage = "<%= config[:homepage_uri] %>"
+<%- if config[:mit] -%>
+  spec.license = "MIT"
+<%- end -%>
+  spec.required_ruby_version = ">= <%= config[:required_ruby_version] %>"
+  spec.metadata["allowed_push_host"] = "TODO: Set to your gem server 'https://example.com'"
+  spec.metadata["homepage_uri"] = spec.homepage
+  spec.metadata["source_code_uri"] = "<%= config[:source_code_uri] %>"
+<%- if config[:changelog] -%>
+  spec.metadata["changelog_uri"] = "<%= config[:changelog_uri] %>"
+<%- end -%>
+
+  # Uncomment the line below to require MFA for gem pushes.
+  # This helps protect your gem from supply chain attacks by ensuring
+  # no one can publish a new version without multi-factor authentication.
+  # See: https://guides.rubygems.org/mfa-requirement-opt-in/
+  # spec.metadata["rubygems_mfa_required"] = "true"
+
+  # Specify which files should be added to the gem when it is released.
+  # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
+  gemspec = File.basename(__FILE__)
+  spec.files = IO.popen(%w[git ls-files -z], chdir: __dir__, err: IO::NULL) do |ls|
+    ls.readlines("\x0", chomp: true).reject do |f|
+      (f == gemspec) ||
+        f.start_with?(*%w[<%= config[:ignore_paths].join(" ") %>])
+    end
+  end
+  spec.bindir = "exe"
+  spec.executables = spec.files.grep(%r{\Aexe/}) { |f| File.basename(f) }
+  spec.require_paths = ["lib"]
+<%- if %w(c rust go).include?(config[:ext]) -%>
+  spec.extensions = ["ext/<%= config[:underscored_name] %>/extconf.rb"]
+<%- end -%>
+
+  # Uncomment to register a new dependency of your gem
+  # spec.add_dependency "example-gem", ">= 1.0"
+<%- if config[:ext] == 'rust' -%>
+  spec.add_dependency "rb_sys", ">= 0.9.128"
+<%- end -%>
+<%- if config[:ext] == 'go' -%>
+  spec.add_dependency "go_gem", ">= 0.2"
+<%- end -%>
+
+  # For more information and examples about making a new gem, check out our
+  # guide at: https://guides.rubygems.org/make-your-own-gem/
+end
diff --git a/lib/bundler/templates/newgem/rspec.tt b/lib/bundler/templates/newgem/rspec.tt
new file mode 100644
index 0000000000..34c5164d9b
--- /dev/null
+++ b/lib/bundler/templates/newgem/rspec.tt
@@ -0,0 +1,3 @@
+--format documentation
+--color
+--require spec_helper
diff --git a/lib/bundler/templates/newgem/rubocop.yml.tt b/lib/bundler/templates/newgem/rubocop.yml.tt
new file mode 100644
index 0000000000..3d1c4ee7b2
--- /dev/null
+++ b/lib/bundler/templates/newgem/rubocop.yml.tt
@@ -0,0 +1,8 @@
+AllCops:
+  TargetRubyVersion: <%= ::Gem::Version.new(config[:required_ruby_version]).segments[0..1].join(".") %>
+
+Style/StringLiterals:
+  EnforcedStyle: double_quotes
+
+Style/StringLiteralsInInterpolation:
+  EnforcedStyle: double_quotes
diff --git a/lib/bundler/templates/newgem/sig/newgem.rbs.tt b/lib/bundler/templates/newgem/sig/newgem.rbs.tt
new file mode 100644
index 0000000000..eb7b380bbb
--- /dev/null
+++ b/lib/bundler/templates/newgem/sig/newgem.rbs.tt
@@ -0,0 +1,8 @@
+<%- config[:constant_array].each_with_index do |c, i| -%>
+<%= "  " * i %>module <%= c %>
+<%- end -%>
+<%= "  " * config[:constant_array].size %>VERSION: String
+<%= "  " * config[:constant_array].size %># See the writing guide of rbs: https://github.com/ruby/rbs#guides
+<%- (config[:constant_array].size-1).downto(0) do |i| -%>
+<%= "  " * i %>end
+<%- end -%>
diff --git a/lib/bundler/templates/newgem/spec/newgem_spec.rb.tt b/lib/bundler/templates/newgem/spec/newgem_spec.rb.tt
new file mode 100644
index 0000000000..7c6cde170b
--- /dev/null
+++ b/lib/bundler/templates/newgem/spec/newgem_spec.rb.tt
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+RSpec.describe <%= config[:constant_name] %> do
+  it "has a version number" do
+    expect(<%= config[:constant_name] %>::VERSION).not_to be nil
+  end
+
+<%- if config[:ext] == 'rust' -%>
+  it "can call into Rust" do
+    result = <%= config[:constant_name] %>.hello("world")
+
+    expect(result).to eq("Hello world, from Rust!")
+  end
+<%- else -%>
+  it "does something useful" do
+    expect(false).to eq(true)
+  end
+<%- end -%>
+end
diff --git a/lib/bundler/templates/newgem/spec/spec_helper.rb.tt b/lib/bundler/templates/newgem/spec/spec_helper.rb.tt
new file mode 100644
index 0000000000..70c6d1fcde
--- /dev/null
+++ b/lib/bundler/templates/newgem/spec/spec_helper.rb.tt
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+require "<%= config[:namespaced_path] %>"
+
+RSpec.configure do |config|
+  # Enable flags like --only-failures and --next-failure
+  config.example_status_persistence_file_path = ".rspec_status"
+
+  # Disable RSpec exposing methods globally on `Module` and `main`
+  config.disable_monkey_patching!
+
+  config.expect_with :rspec do |c|
+    c.syntax = :expect
+  end
+end
diff --git a/lib/bundler/templates/newgem/standard.yml.tt b/lib/bundler/templates/newgem/standard.yml.tt
new file mode 100644
index 0000000000..a0696cd2e9
--- /dev/null
+++ b/lib/bundler/templates/newgem/standard.yml.tt
@@ -0,0 +1,3 @@
+# For available configuration options, see:
+#   https://github.com/standardrb/standard
+ruby_version: <%= ::Gem::Version.new(config[:required_ruby_version]).segments[0..1].join(".") %>
diff --git a/lib/bundler/templates/newgem/test/minitest/test_helper.rb.tt b/lib/bundler/templates/newgem/test/minitest/test_helper.rb.tt
new file mode 100644
index 0000000000..e05c387bfa
--- /dev/null
+++ b/lib/bundler/templates/newgem/test/minitest/test_helper.rb.tt
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+$LOAD_PATH.unshift File.expand_path("../lib", __dir__)
+require "<%= config[:namespaced_path] %>"
+
+require "minitest/autorun"
diff --git a/lib/bundler/templates/newgem/test/minitest/test_newgem.rb.tt b/lib/bundler/templates/newgem/test/minitest/test_newgem.rb.tt
new file mode 100644
index 0000000000..844d3aff81
--- /dev/null
+++ b/lib/bundler/templates/newgem/test/minitest/test_newgem.rb.tt
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+class <%= config[:minitest_constant_name] %> < Minitest::Test
+  def test_that_it_has_a_version_number
+    refute_nil ::<%= config[:constant_name] %>::VERSION
+  end
+
+<%- if config[:ext] == 'rust' -%>
+  def test_hello_world
+    assert_equal "Hello world, from Rust!", <%= config[:constant_name] %>.hello("world")
+  end
+<%- else -%>
+  def test_it_does_something_useful
+    assert false
+  end
+<%- end -%>
+end
diff --git a/lib/bundler/templates/newgem/test/test-unit/newgem_test.rb.tt b/lib/bundler/templates/newgem/test/test-unit/newgem_test.rb.tt
new file mode 100644
index 0000000000..5c61094e62
--- /dev/null
+++ b/lib/bundler/templates/newgem/test/test-unit/newgem_test.rb.tt
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+class <%= config[:constant_name] %>Test < Test::Unit::TestCase
+  test "VERSION" do
+    assert do
+      ::<%= config[:constant_name] %>.const_defined?(:VERSION)
+    end
+  end
+
+  test "something useful" do
+    assert_equal("expected", "actual")
+  end
+end
diff --git a/lib/bundler/templates/newgem/test/test-unit/test_helper.rb.tt b/lib/bundler/templates/newgem/test/test-unit/test_helper.rb.tt
new file mode 100644
index 0000000000..6f633c6039
--- /dev/null
+++ b/lib/bundler/templates/newgem/test/test-unit/test_helper.rb.tt
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+$LOAD_PATH.unshift File.expand_path("../lib", __dir__)
+require "<%= config[:namespaced_path] %>"
+
+require "test-unit"
diff --git a/lib/bundler/ui.rb b/lib/bundler/ui.rb
new file mode 100644
index 0000000000..7a4fa03669
--- /dev/null
+++ b/lib/bundler/ui.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+module Bundler
+  module UI
+    autoload :RGProxy, File.expand_path("ui/rg_proxy", __dir__)
+    autoload :Shell,   File.expand_path("ui/shell", __dir__)
+    autoload :Silent,  File.expand_path("ui/silent", __dir__)
+  end
+end
diff --git a/lib/bundler/ui/rg_proxy.rb b/lib/bundler/ui/rg_proxy.rb
new file mode 100644
index 0000000000..b17ca65f53
--- /dev/null
+++ b/lib/bundler/ui/rg_proxy.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+require_relative "../ui"
+require "rubygems/user_interaction"
+
+module Bundler
+  module UI
+    class RGProxy < ::Gem::SilentUI
+      def initialize(ui)
+        @ui = ui
+        super()
+      end
+
+      def say(message)
+        @ui&.debug(message)
+      end
+    end
+  end
+end
diff --git a/lib/bundler/ui/shell.rb b/lib/bundler/ui/shell.rb
new file mode 100644
index 0000000000..b836208da8
--- /dev/null
+++ b/lib/bundler/ui/shell.rb
@@ -0,0 +1,191 @@
+# frozen_string_literal: true
+
+require_relative "../vendored_thor"
+
+module Bundler
+  module UI
+    class Shell
+      LEVELS = %w[silent error warn confirm info debug].freeze
+      OUTPUT_STREAMS = [:stdout, :stderr].freeze
+
+      attr_writer :shell
+      attr_reader :output_stream
+
+      def initialize(options = {})
+        Thor::Base.shell = options["no-color"] ? Thor::Shell::Basic : nil
+        @shell = Thor::Base.shell.new
+        @level = ENV["DEBUG"] ? "debug" : "info"
+        @warning_history = []
+        @output_stream = :stdout
+        @thread_safe_logger_key = "logger_level_#{object_id}"
+      end
+
+      def add_color(string, *color)
+        @shell.set_color(string, *color)
+      end
+
+      def info(msg = nil, newline = nil)
+        return unless info?
+
+        tell_me(msg || yield, nil, newline)
+      end
+
+      def confirm(msg = nil, newline = nil)
+        return unless confirm?
+
+        tell_me(msg || yield, :green, newline)
+      end
+
+      def warn(msg = nil, newline = nil, color = :yellow)
+        return unless warn?
+        return if @warning_history.include? msg
+        @warning_history << msg
+
+        tell_err(msg || yield, color, newline)
+      end
+
+      def error(msg = nil, newline = nil, color = :red)
+        return unless error?
+
+        tell_err(msg || yield, color, newline)
+      end
+
+      def debug(msg = nil, newline = nil)
+        return unless debug?
+
+        tell_me(msg || yield, nil, newline)
+      end
+
+      def info?
+        level("info")
+      end
+
+      def confirm?
+        level("confirm")
+      end
+
+      def warn?
+        level("warn")
+      end
+
+      def error?
+        level("error")
+      end
+
+      def debug?
+        level("debug")
+      end
+
+      def quiet?
+        level("quiet")
+      end
+
+      def ask(msg)
+        @shell.ask(msg, :green)
+      end
+
+      def yes?(msg)
+        @shell.yes?(msg, :green)
+      end
+
+      def no?(msg)
+        @shell.no?(msg)
+      end
+
+      def level=(level)
+        raise ArgumentError unless LEVELS.include?(level.to_s)
+        @level = level.to_s
+      end
+
+      def level(name = nil)
+        current_level = Thread.current.thread_variable_get(@thread_safe_logger_key) || @level
+        return current_level unless name
+
+        unless index = LEVELS.index(name)
+          raise "#{name.inspect} is not a valid level"
+        end
+        index <= LEVELS.index(current_level)
+      end
+
+      def output_stream=(symbol)
+        raise ArgumentError unless OUTPUT_STREAMS.include?(symbol)
+        @output_stream = symbol
+      end
+
+      def trace(e, newline = nil, force = false)
+        return unless debug? || force
+        msg = "#{e.class}: #{e.message}\n#{e.backtrace.join("\n  ")}"
+        tell_err(msg, nil, newline)
+      end
+
+      def silence(&blk)
+        with_level("silent", &blk)
+      end
+
+      def progress(&blk)
+        with_output_stream(:stderr, &blk)
+      end
+
+      def unprinted_warnings
+        []
+      end
+
+      private
+
+      # valimism
+      def tell_me(msg, color = nil, newline = nil)
+        return tell_err(msg, color, newline) if output_stream == :stderr
+
+        msg = word_wrap(msg) if newline.is_a?(Hash) && newline[:wrap]
+        if newline.nil?
+          @shell.say(msg, color)
+        else
+          @shell.say(msg, color, newline)
+        end
+      end
+
+      def tell_err(message, color = nil, newline = nil)
+        return if @shell.send(:stderr).closed?
+
+        newline = !message.to_s.match?(/( |\t)\Z/) if newline.nil?
+        message = word_wrap(message) if newline.is_a?(Hash) && newline[:wrap]
+
+        color = nil if color && !$stderr.tty?
+
+        buffer = @shell.send(:prepare_message, message, *color)
+        buffer << "\n" if newline && !message.to_s.end_with?("\n")
+
+        @shell.send(:stderr).print(buffer)
+        @shell.send(:stderr).flush
+      end
+
+      def strip_leading_spaces(text)
+        spaces = text[/\A\s+/, 0]
+        spaces ? text.gsub(/#{spaces}/, "") : text
+      end
+
+      def word_wrap(text, line_width = Thor::Terminal.terminal_width)
+        strip_leading_spaces(text).split("\n").collect do |line|
+          line.length > line_width ? line.gsub(/(.{1,#{line_width}})(\s+|$)/, "\\1\n").strip : line
+        end * "\n"
+      end
+
+      def with_level(desired_level)
+        old_level = level
+        Thread.current.thread_variable_set(@thread_safe_logger_key, desired_level)
+
+        yield
+      ensure
+        Thread.current.thread_variable_set(@thread_safe_logger_key, old_level)
+      end
+
+      def with_output_stream(symbol)
+        original = output_stream
+        self.output_stream = symbol
+        yield
+      ensure
+        @output_stream = original
+      end
+    end
+  end
+end
diff --git a/lib/bundler/ui/silent.rb b/lib/bundler/ui/silent.rb
new file mode 100644
index 0000000000..83d31d4b55
--- /dev/null
+++ b/lib/bundler/ui/silent.rb
@@ -0,0 +1,96 @@
+# frozen_string_literal: true
+
+module Bundler
+  module UI
+    class Silent
+      attr_writer :shell
+
+      def initialize
+        @warnings = []
+      end
+
+      def add_color(string, color)
+        string
+      end
+
+      def info(message = nil, newline = nil)
+      end
+
+      def confirm(message = nil, newline = nil)
+      end
+
+      def warn(message = nil, newline = nil)
+        @warnings |= [message]
+      end
+
+      def error(message = nil, newline = nil)
+      end
+
+      def debug(message = nil, newline = nil)
+      end
+
+      def confirm?
+        false
+      end
+
+      def error?
+        false
+      end
+
+      def debug?
+        false
+      end
+
+      def info?
+        false
+      end
+
+      def quiet?
+        false
+      end
+
+      def warn?
+        false
+      end
+
+      def output_stream=(_symbol)
+      end
+
+      def output_stream
+        nil
+      end
+
+      def ask(message)
+      end
+
+      def yes?(msg)
+        raise "Cannot ask yes? with a silent shell"
+      end
+
+      def no?(msg)
+        raise "Cannot ask no? with a silent shell"
+      end
+
+      def level=(name)
+      end
+
+      def level(name = nil)
+      end
+
+      def trace(message, newline = nil, force = false)
+      end
+
+      def silence
+        yield
+      end
+
+      def progress
+        yield
+      end
+
+      def unprinted_warnings
+        @warnings
+      end
+    end
+  end
+end
diff --git a/lib/bundler/uri_credentials_filter.rb b/lib/bundler/uri_credentials_filter.rb
new file mode 100644
index 0000000000..6804187433
--- /dev/null
+++ b/lib/bundler/uri_credentials_filter.rb
@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+module Bundler
+  module URICredentialsFilter
+    module_function
+
+    def credential_filtered_uri(uri_to_anonymize)
+      return uri_to_anonymize if uri_to_anonymize.nil?
+      uri = uri_to_anonymize.dup
+      if uri.is_a?(String)
+        return uri if File.exist?(uri)
+
+        require_relative "vendored_uri"
+        uri = Gem::URI(uri)
+      end
+
+      if uri.userinfo
+        # oauth authentication
+        if uri.password == "x-oauth-basic" || uri.password == "x" || uri.password.nil?
+          # URI as string does not display with password if no user is set
+          oauth_designation = uri.password
+          uri.user = oauth_designation
+        end
+        uri.password = nil
+      end
+      return uri.to_s if uri_to_anonymize.is_a?(String)
+      uri
+    rescue Gem::URI::InvalidURIError # uri is not canonical uri scheme
+      uri
+    end
+
+    def credential_filtered_string(str_to_filter, uri)
+      return str_to_filter if uri.nil? || str_to_filter.nil?
+      str_with_no_credentials = str_to_filter.dup
+      anonymous_uri_str = credential_filtered_uri(uri).to_s
+      uri_str = uri.to_s
+      if anonymous_uri_str != uri_str
+        str_with_no_credentials = str_with_no_credentials.gsub(uri_str, anonymous_uri_str)
+      end
+      str_with_no_credentials
+    end
+  end
+end
diff --git a/lib/bundler/uri_normalizer.rb b/lib/bundler/uri_normalizer.rb
new file mode 100644
index 0000000000..ad08593256
--- /dev/null
+++ b/lib/bundler/uri_normalizer.rb
@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+module Bundler
+  module URINormalizer
+    module_function
+
+    # Normalizes uri to a consistent version, either with or without trailing
+    # slash.
+    #
+    # TODO: Currently gem sources are locked with a trailing slash, while git
+    # sources are locked without a trailing slash. This should be normalized but
+    # the inconsistency is there for now to avoid changing all lockfiles
+    # including GIT sources. We could normalize this on the next major.
+    #
+    def normalize_suffix(uri, trailing_slash: true)
+      if trailing_slash
+        uri.end_with?("/") ? uri : "#{uri}/"
+      else
+        uri.end_with?("/") ? uri.delete_suffix("/") : uri
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/.document b/lib/bundler/vendor/.document
new file mode 100644
index 0000000000..0c43bbd6b3
--- /dev/null
+++ b/lib/bundler/vendor/.document
@@ -0,0 +1 @@
+# Vendored files do not need to be documented
diff --git a/lib/bundler/vendor/connection_pool/lib/connection_pool.rb b/lib/bundler/vendor/connection_pool/lib/connection_pool.rb
new file mode 100644
index 0000000000..e8aaf70016
--- /dev/null
+++ b/lib/bundler/vendor/connection_pool/lib/connection_pool.rb
@@ -0,0 +1,233 @@
+require_relative "../../../vendored_timeout"
+require_relative "connection_pool/version"
+
+class Bundler::ConnectionPool
+  class Error < ::RuntimeError; end
+
+  class PoolShuttingDownError < ::Bundler::ConnectionPool::Error; end
+
+  class TimeoutError < ::Gem::Timeout::Error; end
+end
+
+# Generic connection pool class for sharing a limited number of objects or network connections
+# among many threads.  Note: pool elements are lazily created.
+#
+# Example usage with block (faster):
+#
+#    @pool = Bundler::ConnectionPool.new { Redis.new }
+#    @pool.with do |redis|
+#      redis.lpop('my-list') if redis.llen('my-list') > 0
+#    end
+#
+# Using optional timeout override (for that single invocation)
+#
+#    @pool.with(timeout: 2.0) do |redis|
+#      redis.lpop('my-list') if redis.llen('my-list') > 0
+#    end
+#
+# Example usage replacing an existing connection (slower):
+#
+#    $redis = Bundler::ConnectionPool.wrap { Redis.new }
+#
+#    def do_work
+#      $redis.lpop('my-list') if $redis.llen('my-list') > 0
+#    end
+#
+# Accepts the following options:
+# - :size - number of connections to pool, defaults to 5
+# - :timeout - amount of time to wait for a connection if none currently available, defaults to 5 seconds
+# - :auto_reload_after_fork - automatically drop all connections after fork, defaults to true
+#
+class Bundler::ConnectionPool
+  DEFAULTS = {size: 5, timeout: 5, auto_reload_after_fork: true}.freeze
+
+  def self.wrap(options, &block)
+    Wrapper.new(options, &block)
+  end
+
+  if Process.respond_to?(:fork)
+    INSTANCES = ObjectSpace::WeakMap.new
+    private_constant :INSTANCES
+
+    def self.after_fork
+      INSTANCES.values.each do |pool|
+        next unless pool.auto_reload_after_fork
+
+        # We're on after fork, so we know all other threads are dead.
+        # All we need to do is to ensure the main thread doesn't have a
+        # checked out connection
+        pool.checkin(force: true)
+        pool.reload do |connection|
+          # Unfortunately we don't know what method to call to close the connection,
+          # so we try the most common one.
+          connection.close if connection.respond_to?(:close)
+        end
+      end
+      nil
+    end
+
+    if ::Process.respond_to?(:_fork) # MRI 3.1+
+      module ForkTracker
+        def _fork
+          pid = super
+          if pid == 0
+            Bundler::ConnectionPool.after_fork
+          end
+          pid
+        end
+      end
+      Process.singleton_class.prepend(ForkTracker)
+    end
+  else
+    INSTANCES = nil
+    private_constant :INSTANCES
+
+    def self.after_fork
+      # noop
+    end
+  end
+
+  def initialize(options = {}, &block)
+    raise ArgumentError, "Connection pool requires a block" unless block
+
+    options = DEFAULTS.merge(options)
+
+    @size = Integer(options.fetch(:size))
+    @timeout = options.fetch(:timeout)
+    @auto_reload_after_fork = options.fetch(:auto_reload_after_fork)
+
+    @available = TimedStack.new(@size, &block)
+    @key = :"pool-#{@available.object_id}"
+    @key_count = :"pool-#{@available.object_id}-count"
+    @discard_key = :"pool-#{@available.object_id}-discard"
+    INSTANCES[self] = self if @auto_reload_after_fork && INSTANCES
+  end
+
+  def with(options = {})
+    # We need to manage exception handling manually here in order
+    # to work correctly with `Gem::Timeout.timeout` and `Thread#raise`.
+    # Otherwise an interrupted Thread can leak connections.
+    Thread.handle_interrupt(Exception => :never) do
+      conn = checkout(options)
+      begin
+        Thread.handle_interrupt(Exception => :immediate) do
+          yield conn
+        end
+      ensure
+        checkin
+      end
+    end
+  end
+  alias_method :then, :with
+
+  ##
+  # Marks the current thread's checked-out connection for discard.
+  #
+  # When a connection is marked for discard, it will not be returned to the pool
+  # when checked in. Instead, the connection will be discarded.
+  # This is useful when a connection has become invalid or corrupted
+  # and should not be reused.
+  #
+  # Takes an optional block that will be called with the connection to be discarded.
+  # The block should perform any necessary clean-up on the connection.
+  #
+  # @yield [conn]
+  # @yieldparam conn [Object] The connection to be discarded.
+  # @yieldreturn [void]
+  #
+  #
+  # Note: This only affects the connection currently checked out by the calling thread.
+  # The connection will be discarded when +checkin+ is called.
+  #
+  # @return [void]
+  #
+  # @example
+  #   pool.with do |conn|
+  #     begin
+  #       conn.execute("SELECT 1")
+  #     rescue SomeConnectionError
+  #       pool.discard_current_connection  # Mark connection as bad
+  #       raise
+  #     end
+  #   end
+  def discard_current_connection(&block)
+    ::Thread.current[@discard_key] = block || proc { |conn| conn }
+  end
+
+  def checkout(options = {})
+    if ::Thread.current[@key]
+      ::Thread.current[@key_count] += 1
+      ::Thread.current[@key]
+    else
+      ::Thread.current[@key_count] = 1
+      ::Thread.current[@key] = @available.pop(options[:timeout] || @timeout, options)
+    end
+  end
+
+  def checkin(force: false)
+    if ::Thread.current[@key]
+      if ::Thread.current[@key_count] == 1 || force
+        if ::Thread.current[@discard_key]
+          begin
+            @available.decrement_created
+            ::Thread.current[@discard_key].call(::Thread.current[@key])
+          rescue
+            nil
+          ensure
+            ::Thread.current[@discard_key] = nil
+          end
+        else
+          @available.push(::Thread.current[@key])
+        end
+        ::Thread.current[@key] = nil
+        ::Thread.current[@key_count] = nil
+      else
+        ::Thread.current[@key_count] -= 1
+      end
+    elsif !force
+      raise Bundler::ConnectionPool::Error, "no connections are checked out"
+    end
+
+    nil
+  end
+
+  ##
+  # Shuts down the Bundler::ConnectionPool by passing each connection to +block+ and
+  # then removing it from the pool. Attempting to checkout a connection after
+  # shutdown will raise +Bundler::ConnectionPool::PoolShuttingDownError+.
+  def shutdown(&block)
+    @available.shutdown(&block)
+  end
+
+  ##
+  # Reloads the Bundler::ConnectionPool by passing each connection to +block+ and then
+  # removing it the pool. Subsequent checkouts will create new connections as
+  # needed.
+  def reload(&block)
+    @available.shutdown(reload: true, &block)
+  end
+
+  ## Reaps idle connections that have been idle for over +idle_seconds+.
+  # +idle_seconds+ defaults to 60.
+  def reap(idle_seconds = 60, &block)
+    @available.reap(idle_seconds, &block)
+  end
+
+  # Size of this connection pool
+  attr_reader :size
+  # Automatically drop all connections after fork
+  attr_reader :auto_reload_after_fork
+
+  # Number of pool entries available for checkout at this instant.
+  def available
+    @available.length
+  end
+
+  # Number of pool entries created and idle in the pool.
+  def idle
+    @available.idle
+  end
+end
+
+require_relative "connection_pool/timed_stack"
+require_relative "connection_pool/wrapper"
diff --git a/lib/bundler/vendor/connection_pool/lib/connection_pool/timed_stack.rb b/lib/bundler/vendor/connection_pool/lib/connection_pool/timed_stack.rb
new file mode 100644
index 0000000000..026d2c5be2
--- /dev/null
+++ b/lib/bundler/vendor/connection_pool/lib/connection_pool/timed_stack.rb
@@ -0,0 +1,237 @@
+##
+# The TimedStack manages a pool of homogeneous connections (or any resource
+# you wish to manage). Connections are created lazily up to a given maximum
+# number.
+#
+# Examples:
+#
+#    ts = TimedStack.new(1) { MyConnection.new }
+#
+#    # fetch a connection
+#    conn = ts.pop
+#
+#    # return a connection
+#    ts.push conn
+#
+#    conn = ts.pop
+#    ts.pop timeout: 5
+#    #=> raises Bundler::ConnectionPool::TimeoutError after 5 seconds
+class Bundler::ConnectionPool::TimedStack
+  attr_reader :max
+
+  ##
+  # Creates a new pool with +size+ connections that are created from the given
+  # +block+.
+  def initialize(size = 0, &block)
+    @create_block = block
+    @created = 0
+    @que = []
+    @max = size
+    @mutex = Thread::Mutex.new
+    @resource = Thread::ConditionVariable.new
+    @shutdown_block = nil
+  end
+
+  ##
+  # Returns +obj+ to the stack. +options+ is ignored in TimedStack but may be
+  # used by subclasses that extend TimedStack.
+  def push(obj, options = {})
+    @mutex.synchronize do
+      if @shutdown_block
+        @created -= 1 unless @created == 0
+        @shutdown_block.call(obj)
+      else
+        store_connection obj, options
+      end
+
+      @resource.broadcast
+    end
+  end
+  alias_method :<<, :push
+
+  ##
+  # Retrieves a connection from the stack. If a connection is available it is
+  # immediately returned. If no connection is available within the given
+  # timeout a Bundler::ConnectionPool::TimeoutError is raised.
+  #
+  # @option options [Float] :timeout (0.5) Wait this many seconds for an available entry
+  # @option options [Class] :exception (Bundler::ConnectionPool::TimeoutError) Exception class to raise
+  #   if an entry was not available within the timeout period. Use `exception: false` to return nil.
+  #
+  # The +timeout+ argument will be removed in 3.0.
+  # Other options may be used by subclasses that extend TimedStack.
+  def pop(timeout = 0.5, options = {})
+    options, timeout = timeout, 0.5 if Hash === timeout
+    timeout = options.fetch :timeout, timeout
+
+    deadline = current_time + timeout
+    @mutex.synchronize do
+      loop do
+        raise Bundler::ConnectionPool::PoolShuttingDownError if @shutdown_block
+        if (conn = try_fetch_connection(options))
+          return conn
+        end
+
+        connection = try_create(options)
+        return connection if connection
+
+        to_wait = deadline - current_time
+        if to_wait <= 0
+          exc = options.fetch(:exception, Bundler::ConnectionPool::TimeoutError)
+          if exc
+            raise Bundler::ConnectionPool::TimeoutError, "Waited #{timeout} sec, #{length}/#{@max} available"
+          else
+            return nil
+          end
+        end
+        @resource.wait(@mutex, to_wait)
+      end
+    end
+  end
+
+  ##
+  # Shuts down the TimedStack by passing each connection to +block+ and then
+  # removing it from the pool. Attempting to checkout a connection after
+  # shutdown will raise +Bundler::ConnectionPool::PoolShuttingDownError+ unless
+  # +:reload+ is +true+.
+  def shutdown(reload: false, &block)
+    raise ArgumentError, "shutdown must receive a block" unless block
+
+    @mutex.synchronize do
+      @shutdown_block = block
+      @resource.broadcast
+
+      shutdown_connections
+      @shutdown_block = nil if reload
+    end
+  end
+
+  ##
+  # Reaps connections that were checked in more than +idle_seconds+ ago.
+  def reap(idle_seconds, &block)
+    raise ArgumentError, "reap must receive a block" unless block
+    raise ArgumentError, "idle_seconds must be a number" unless idle_seconds.is_a?(Numeric)
+    raise Bundler::ConnectionPool::PoolShuttingDownError if @shutdown_block
+
+    idle.times do
+      conn =
+        @mutex.synchronize do
+          raise Bundler::ConnectionPool::PoolShuttingDownError if @shutdown_block
+
+          reserve_idle_connection(idle_seconds)
+        end
+      break unless conn
+
+      block.call(conn)
+    end
+  end
+
+  ##
+  # Returns +true+ if there are no available connections.
+  def empty?
+    (@created - @que.length) >= @max
+  end
+
+  ##
+  # The number of connections available on the stack.
+  def length
+    @max - @created + @que.length
+  end
+
+  ##
+  # The number of connections created and available on the stack.
+  def idle
+    @que.length
+  end
+
+  ##
+  # Reduce the created count
+  def decrement_created
+    @created -= 1 unless @created == 0
+  end
+
+  private
+
+  def current_time
+    Process.clock_gettime(Process::CLOCK_MONOTONIC)
+  end
+
+  ##
+  # This is an extension point for TimedStack and is called with a mutex.
+  #
+  # This method must returns a connection from the stack if one exists. Allows
+  # subclasses with expensive match/search algorithms to avoid double-handling
+  # their stack.
+  def try_fetch_connection(options = nil)
+    connection_stored?(options) && fetch_connection(options)
+  end
+
+  ##
+  # This is an extension point for TimedStack and is called with a mutex.
+  #
+  # This method must returns true if a connection is available on the stack.
+  def connection_stored?(options = nil)
+    !@que.empty?
+  end
+
+  ##
+  # This is an extension point for TimedStack and is called with a mutex.
+  #
+  # This method must return a connection from the stack.
+  def fetch_connection(options = nil)
+    @que.pop&.first
+  end
+
+  ##
+  # This is an extension point for TimedStack and is called with a mutex.
+  #
+  # This method must shut down all connections on the stack.
+  def shutdown_connections(options = nil)
+    while (conn = try_fetch_connection(options))
+      @created -= 1 unless @created == 0
+      @shutdown_block.call(conn)
+    end
+  end
+
+  ##
+  # This is an extension point for TimedStack and is called with a mutex.
+  #
+  # This method returns the oldest idle connection if it has been idle for more than idle_seconds.
+  # This requires that the stack is kept in order of checked in time (oldest first).
+  def reserve_idle_connection(idle_seconds)
+    return unless idle_connections?(idle_seconds)
+
+    @created -= 1 unless @created == 0
+
+    @que.shift.first
+  end
+
+  ##
+  # This is an extension point for TimedStack and is called with a mutex.
+  #
+  # Returns true if the first connection in the stack has been idle for more than idle_seconds
+  def idle_connections?(idle_seconds)
+    connection_stored? && (current_time - @que.first.last > idle_seconds)
+  end
+
+  ##
+  # This is an extension point for TimedStack and is called with a mutex.
+  #
+  # This method must return +obj+ to the stack.
+  def store_connection(obj, options = nil)
+    @que.push [obj, current_time]
+  end
+
+  ##
+  # This is an extension point for TimedStack and is called with a mutex.
+  #
+  # This method must create a connection if and only if the total number of
+  # connections allowed has not been met.
+  def try_create(options = nil)
+    unless @created == @max
+      object = @create_block.call
+      @created += 1
+      object
+    end
+  end
+end
diff --git a/lib/bundler/vendor/connection_pool/lib/connection_pool/version.rb b/lib/bundler/vendor/connection_pool/lib/connection_pool/version.rb
new file mode 100644
index 0000000000..2e9eebdbb6
--- /dev/null
+++ b/lib/bundler/vendor/connection_pool/lib/connection_pool/version.rb
@@ -0,0 +1,3 @@
+class Bundler::ConnectionPool
+  VERSION = "2.5.5"
+end
diff --git a/lib/bundler/vendor/connection_pool/lib/connection_pool/wrapper.rb b/lib/bundler/vendor/connection_pool/lib/connection_pool/wrapper.rb
new file mode 100644
index 0000000000..dd796d1021
--- /dev/null
+++ b/lib/bundler/vendor/connection_pool/lib/connection_pool/wrapper.rb
@@ -0,0 +1,56 @@
+class Bundler::ConnectionPool
+  class Wrapper < ::BasicObject
+    METHODS = [:with, :pool_shutdown, :wrapped_pool]
+
+    def initialize(options = {}, &block)
+      @pool = options.fetch(:pool) { ::Bundler::ConnectionPool.new(options, &block) }
+    end
+
+    def wrapped_pool
+      @pool
+    end
+
+    def with(&block)
+      @pool.with(&block)
+    end
+
+    def pool_shutdown(&block)
+      @pool.shutdown(&block)
+    end
+
+    def pool_size
+      @pool.size
+    end
+
+    def pool_available
+      @pool.available
+    end
+
+    def respond_to?(id, *args)
+      METHODS.include?(id) || with { |c| c.respond_to?(id, *args) }
+    end
+
+    # rubocop:disable Style/MissingRespondToMissing
+    if ::RUBY_VERSION >= "3.0.0"
+      def method_missing(name, *args, **kwargs, &block)
+        with do |connection|
+          connection.send(name, *args, **kwargs, &block)
+        end
+      end
+    elsif ::RUBY_VERSION >= "2.7.0"
+      ruby2_keywords def method_missing(name, *args, &block)
+        with do |connection|
+          connection.send(name, *args, &block)
+        end
+      end
+    else
+      def method_missing(name, *args, &block)
+        with do |connection|
+          connection.send(name, *args, &block)
+        end
+      end
+    end
+    # rubocop:enable Style/MethodMissingSuper
+    # rubocop:enable Style/MissingRespondToMissing
+  end
+end
diff --git a/lib/bundler/vendor/fileutils/lib/fileutils.rb b/lib/bundler/vendor/fileutils/lib/fileutils.rb
new file mode 100644
index 0000000000..a11fdc7176
--- /dev/null
+++ b/lib/bundler/vendor/fileutils/lib/fileutils.rb
@@ -0,0 +1,2701 @@
+# frozen_string_literal: true
+
+begin
+  require 'rbconfig'
+rescue LoadError
+  # for make rjit-headers
+end
+
+# Namespace for file utility methods for copying, moving, removing, etc.
+#
+# == What's Here
+#
+# First, what’s elsewhere. \Module \Bundler::FileUtils:
+#
+# - Inherits from {class Object}[rdoc-ref:Object].
+# - Supplements {class File}[rdoc-ref:File]
+#   (but is not included or extended there).
+#
+# Here, module \Bundler::FileUtils provides methods that are useful for:
+#
+# - {Creating}[rdoc-ref:FileUtils@Creating].
+# - {Deleting}[rdoc-ref:FileUtils@Deleting].
+# - {Querying}[rdoc-ref:FileUtils@Querying].
+# - {Setting}[rdoc-ref:FileUtils@Setting].
+# - {Comparing}[rdoc-ref:FileUtils@Comparing].
+# - {Copying}[rdoc-ref:FileUtils@Copying].
+# - {Moving}[rdoc-ref:FileUtils@Moving].
+# - {Options}[rdoc-ref:FileUtils@Options].
+#
+# === Creating
+#
+# - ::mkdir: Creates directories.
+# - ::mkdir_p, ::makedirs, ::mkpath: Creates directories,
+#   also creating ancestor directories as needed.
+# - ::link_entry: Creates a hard link.
+# - ::ln, ::link: Creates hard links.
+# - ::ln_s, ::symlink: Creates symbolic links.
+# - ::ln_sf: Creates symbolic links, overwriting if necessary.
+# - ::ln_sr: Creates symbolic links relative to targets
+#
+# === Deleting
+#
+# - ::remove_dir: Removes a directory and its descendants.
+# - ::remove_entry: Removes an entry, including its descendants if it is a directory.
+# - ::remove_entry_secure: Like ::remove_entry, but removes securely.
+# - ::remove_file: Removes a file entry.
+# - ::rm, ::remove: Removes entries.
+# - ::rm_f, ::safe_unlink: Like ::rm, but removes forcibly.
+# - ::rm_r: Removes entries and their descendants.
+# - ::rm_rf, ::rmtree: Like ::rm_r, but removes forcibly.
+# - ::rmdir: Removes directories.
+#
+# === Querying
+#
+# - ::pwd, ::getwd: Returns the path to the working directory.
+# - ::uptodate?: Returns whether a given entry is newer than given other entries.
+#
+# === Setting
+#
+# - ::cd, ::chdir: Sets the working directory.
+# - ::chmod: Sets permissions for an entry.
+# - ::chmod_R: Sets permissions for an entry and its descendants.
+# - ::chown: Sets the owner and group for entries.
+# - ::chown_R: Sets the owner and group for entries and their descendants.
+# - ::touch: Sets modification and access times for entries,
+#   creating if necessary.
+#
+# === Comparing
+#
+# - ::compare_file, ::cmp, ::identical?: Returns whether two entries are identical.
+# - ::compare_stream: Returns whether two streams are identical.
+#
+# === Copying
+#
+# - ::copy_entry: Recursively copies an entry.
+# - ::copy_file: Copies an entry.
+# - ::copy_stream: Copies a stream.
+# - ::cp, ::copy: Copies files.
+# - ::cp_lr: Recursively creates hard links.
+# - ::cp_r: Recursively copies files, retaining mode, owner, and group.
+# - ::install: Recursively copies files, optionally setting mode,
+#   owner, and group.
+#
+# === Moving
+#
+# - ::mv, ::move: Moves entries.
+#
+# === Options
+#
+# - ::collect_method: Returns the names of methods that accept a given option.
+# - ::commands: Returns the names of methods that accept options.
+# - ::have_option?: Returns whether a given method accepts a given option.
+# - ::options: Returns all option names.
+# - ::options_of: Returns the names of the options for a given method.
+#
+# == Path Arguments
+#
+# Some methods in \Bundler::FileUtils accept _path_ arguments,
+# which are interpreted as paths to filesystem entries:
+#
+# - If the argument is a string, that value is the path.
+# - If the argument has method +:to_path+, it is converted via that method.
+# - If the argument has method +:to_str+, it is converted via that method.
+#
+# == About the Examples
+#
+# Some examples here involve trees of file entries.
+# For these, we sometimes display trees using the
+# {tree command-line utility}[https://en.wikipedia.org/wiki/Tree_(command)],
+# which is a recursive directory-listing utility that produces
+# a depth-indented listing of files and directories.
+#
+# We use a helper method to launch the command and control the format:
+#
+#   def tree(dirpath = '.')
+#     command = "tree --noreport --charset=ascii #{dirpath}"
+#     system(command)
+#   end
+#
+# To illustrate:
+#
+#   tree('src0')
+#   # => src0
+#   #    |-- sub0
+#   #    |   |-- src0.txt
+#   #    |   `-- src1.txt
+#   #    `-- sub1
+#   #        |-- src2.txt
+#   #        `-- src3.txt
+#
+# == Avoiding the TOCTTOU Vulnerability
+#
+# For certain methods that recursively remove entries,
+# there is a potential vulnerability called the
+# {Time-of-check to time-of-use}[https://en.wikipedia.org/wiki/Time-of-check_to_time-of-use],
+# or TOCTTOU, vulnerability that can exist when:
+#
+# - An ancestor directory of the entry at the target path is world writable;
+#   such directories include <tt>/tmp</tt>.
+# - The directory tree at the target path includes:
+#
+#   - A world-writable descendant directory.
+#   - A symbolic link.
+#
+# To avoid that vulnerability, you can use this method to remove entries:
+#
+# - Bundler::FileUtils.remove_entry_secure: removes recursively
+#   if the target path points to a directory.
+#
+# Also available are these methods,
+# each of which calls \Bundler::FileUtils.remove_entry_secure:
+#
+# - Bundler::FileUtils.rm_r with keyword argument <tt>secure: true</tt>.
+# - Bundler::FileUtils.rm_rf with keyword argument <tt>secure: true</tt>.
+#
+# Finally, this method for moving entries calls \Bundler::FileUtils.remove_entry_secure
+# if the source and destination are on different file systems
+# (which means that the "move" is really a copy and remove):
+#
+# - Bundler::FileUtils.mv with keyword argument <tt>secure: true</tt>.
+#
+# \Method \Bundler::FileUtils.remove_entry_secure removes securely
+# by applying a special pre-process:
+#
+# - If the target path points to a directory, this method uses methods
+#   {File#chown}[rdoc-ref:File#chown]
+#   and {File#chmod}[rdoc-ref:File#chmod]
+#   in removing directories.
+# - The owner of the target directory should be either the current process
+#   or the super user (root).
+#
+# WARNING: You must ensure that *ALL* parent directories cannot be
+# moved by other untrusted users.  For example, parent directories
+# should not be owned by untrusted users, and should not be world
+# writable except when the sticky bit is set.
+#
+# For details of this security vulnerability, see Perl cases:
+#
+# - {CVE-2005-0448}[https://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-0448].
+# - {CVE-2004-0452}[https://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2004-0452].
+#
+module Bundler::FileUtils
+  # The version number.
+  VERSION = "1.8.0"
+
+  def self.private_module_function(name)   #:nodoc:
+    module_function name
+    private_class_method name
+  end
+
+  #
+  # Returns a string containing the path to the current directory:
+  #
+  #   Bundler::FileUtils.pwd # => "/rdoc/fileutils"
+  #
+  # Related: Bundler::FileUtils.cd.
+  #
+  def pwd
+    Dir.pwd
+  end
+  module_function :pwd
+
+  alias getwd pwd
+  module_function :getwd
+
+  # Changes the working directory to the given +dir+, which
+  # should be {interpretable as a path}[rdoc-ref:FileUtils@Path+Arguments]:
+  #
+  # With no block given,
+  # changes the current directory to the directory at +dir+; returns zero:
+  #
+  #   Bundler::FileUtils.pwd # => "/rdoc/fileutils"
+  #   Bundler::FileUtils.cd('..')
+  #   Bundler::FileUtils.pwd # => "/rdoc"
+  #   Bundler::FileUtils.cd('fileutils')
+  #
+  # With a block given, changes the current directory to the directory
+  # at +dir+, calls the block with argument +dir+,
+  # and restores the original current directory; returns the block's value:
+  #
+  #   Bundler::FileUtils.pwd                                     # => "/rdoc/fileutils"
+  #   Bundler::FileUtils.cd('..') { |arg| [arg, Bundler::FileUtils.pwd] } # => ["..", "/rdoc"]
+  #   Bundler::FileUtils.pwd                                     # => "/rdoc/fileutils"
+  #
+  # Keyword arguments:
+  #
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     Bundler::FileUtils.cd('..')
+  #     Bundler::FileUtils.cd('fileutils')
+  #
+  #   Output:
+  #
+  #     cd ..
+  #     cd fileutils
+  #
+  # Related: Bundler::FileUtils.pwd.
+  #
+  def cd(dir, verbose: nil, &block) # :yield: dir
+    fu_output_message "cd #{dir}" if verbose
+    result = Dir.chdir(dir, &block)
+    fu_output_message 'cd -' if verbose and block
+    result
+  end
+  module_function :cd
+
+  alias chdir cd
+  module_function :chdir
+
+  #
+  # Returns +true+ if the file at path +new+
+  # is newer than all the files at paths in array +old_list+;
+  # +false+ otherwise.
+  #
+  # Argument +new+ and the elements of +old_list+
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments]:
+  #
+  #   Bundler::FileUtils.uptodate?('Rakefile', ['Gemfile', 'README.md']) # => true
+  #   Bundler::FileUtils.uptodate?('Gemfile', ['Rakefile', 'README.md']) # => false
+  #
+  # A non-existent file is considered to be infinitely old.
+  #
+  # Related: Bundler::FileUtils.touch.
+  #
+  def uptodate?(new, old_list)
+    return false unless File.exist?(new)
+    new_time = File.mtime(new)
+    old_list.each do |old|
+      if File.exist?(old)
+        return false unless new_time > File.mtime(old)
+      end
+    end
+    true
+  end
+  module_function :uptodate?
+
+  def remove_trailing_slash(dir)   #:nodoc:
+    dir == '/' ? dir : dir.chomp(?/)
+  end
+  private_module_function :remove_trailing_slash
+
+  #
+  # Creates directories at the paths in the given +list+
+  # (a single path or an array of paths);
+  # returns +list+ if it is an array, <tt>[list]</tt> otherwise.
+  #
+  # Argument +list+ or its elements
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # With no keyword arguments, creates a directory at each +path+ in +list+
+  # by calling: <tt>Dir.mkdir(path, mode)</tt>;
+  # see {Dir.mkdir}[rdoc-ref:Dir.mkdir]:
+  #
+  #   Bundler::FileUtils.mkdir(%w[tmp0 tmp1]) # => ["tmp0", "tmp1"]
+  #   Bundler::FileUtils.mkdir('tmp4')        # => ["tmp4"]
+  #
+  # Keyword arguments:
+  #
+  # - <tt>mode: <i>mode</i></tt> - also calls <tt>File.chmod(mode, path)</tt>;
+  #   see {File.chmod}[rdoc-ref:File.chmod].
+  # - <tt>noop: true</tt> - does not create directories.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     Bundler::FileUtils.mkdir(%w[tmp0 tmp1], verbose: true)
+  #     Bundler::FileUtils.mkdir(%w[tmp2 tmp3], mode: 0700, verbose: true)
+  #
+  #   Output:
+  #
+  #     mkdir tmp0 tmp1
+  #     mkdir -m 700 tmp2 tmp3
+  #
+  # Raises an exception if any path points to an existing
+  # file or directory, or if for any reason a directory cannot be created.
+  #
+  # Related: Bundler::FileUtils.mkdir_p.
+  #
+  def mkdir(list, mode: nil, noop: nil, verbose: nil)
+    list = fu_list(list)
+    fu_output_message "mkdir #{mode ? ('-m %03o ' % mode) : ''}#{list.join ' '}" if verbose
+    return if noop
+
+    list.each do |dir|
+      fu_mkdir dir, mode
+    end
+  end
+  module_function :mkdir
+
+  #
+  # Creates directories at the paths in the given +list+
+  # (a single path or an array of paths),
+  # also creating ancestor directories as needed;
+  # returns +list+ if it is an array, <tt>[list]</tt> otherwise.
+  #
+  # Argument +list+ or its elements
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # With no keyword arguments, creates a directory at each +path+ in +list+,
+  # along with any needed ancestor directories,
+  # by calling: <tt>Dir.mkdir(path, mode)</tt>;
+  # see {Dir.mkdir}[rdoc-ref:Dir.mkdir]:
+  #
+  #   Bundler::FileUtils.mkdir_p(%w[tmp0/tmp1 tmp2/tmp3]) # => ["tmp0/tmp1", "tmp2/tmp3"]
+  #   Bundler::FileUtils.mkdir_p('tmp4/tmp5')             # => ["tmp4/tmp5"]
+  #
+  # Keyword arguments:
+  #
+  # - <tt>mode: <i>mode</i></tt> - also calls <tt>File.chmod(mode, path)</tt>;
+  #   see {File.chmod}[rdoc-ref:File.chmod].
+  # - <tt>noop: true</tt> - does not create directories.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     Bundler::FileUtils.mkdir_p(%w[tmp0 tmp1], verbose: true)
+  #     Bundler::FileUtils.mkdir_p(%w[tmp2 tmp3], mode: 0700, verbose: true)
+  #
+  #   Output:
+  #
+  #     mkdir -p tmp0 tmp1
+  #     mkdir -p -m 700 tmp2 tmp3
+  #
+  # Raises an exception if for any reason a directory cannot be created.
+  #
+  # Bundler::FileUtils.mkpath and Bundler::FileUtils.makedirs are aliases for Bundler::FileUtils.mkdir_p.
+  #
+  # Related: Bundler::FileUtils.mkdir.
+  #
+  def mkdir_p(list, mode: nil, noop: nil, verbose: nil)
+    list = fu_list(list)
+    fu_output_message "mkdir -p #{mode ? ('-m %03o ' % mode) : ''}#{list.join ' '}" if verbose
+    return *list if noop
+
+    list.each do |item|
+      path = remove_trailing_slash(item)
+
+      stack = []
+      until File.directory?(path) || File.dirname(path) == path
+        stack.push path
+        path = File.dirname(path)
+      end
+      stack.reverse_each do |dir|
+        begin
+          fu_mkdir dir, mode
+        rescue SystemCallError
+          raise unless File.directory?(dir)
+        end
+      end
+    end
+
+    return *list
+  end
+  module_function :mkdir_p
+
+  alias mkpath    mkdir_p
+  alias makedirs  mkdir_p
+  module_function :mkpath
+  module_function :makedirs
+
+  def fu_mkdir(path, mode)   #:nodoc:
+    path = remove_trailing_slash(path)
+    if mode
+      Dir.mkdir path, mode
+      File.chmod mode, path
+    else
+      Dir.mkdir path
+    end
+  end
+  private_module_function :fu_mkdir
+
+  #
+  # Removes directories at the paths in the given +list+
+  # (a single path or an array of paths);
+  # returns +list+, if it is an array, <tt>[list]</tt> otherwise.
+  #
+  # Argument +list+ or its elements
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # With no keyword arguments, removes the directory at each +path+ in +list+,
+  # by calling: <tt>Dir.rmdir(path)</tt>;
+  # see {Dir.rmdir}[rdoc-ref:Dir.rmdir]:
+  #
+  #   Bundler::FileUtils.rmdir(%w[tmp0/tmp1 tmp2/tmp3]) # => ["tmp0/tmp1", "tmp2/tmp3"]
+  #   Bundler::FileUtils.rmdir('tmp4/tmp5')             # => ["tmp4/tmp5"]
+  #
+  # Keyword arguments:
+  #
+  # - <tt>parents: true</tt> - removes successive ancestor directories
+  #   if empty.
+  # - <tt>noop: true</tt> - does not remove directories.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     Bundler::FileUtils.rmdir(%w[tmp0/tmp1 tmp2/tmp3], parents: true, verbose: true)
+  #     Bundler::FileUtils.rmdir('tmp4/tmp5', parents: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     rmdir -p tmp0/tmp1 tmp2/tmp3
+  #     rmdir -p tmp4/tmp5
+  #
+  # Raises an exception if a directory does not exist
+  # or if for any reason a directory cannot be removed.
+  #
+  # Related: {methods for deleting}[rdoc-ref:FileUtils@Deleting].
+  #
+  def rmdir(list, parents: nil, noop: nil, verbose: nil)
+    list = fu_list(list)
+    fu_output_message "rmdir #{parents ? '-p ' : ''}#{list.join ' '}" if verbose
+    return if noop
+    list.each do |dir|
+      Dir.rmdir(dir = remove_trailing_slash(dir))
+      if parents
+        begin
+          until (parent = File.dirname(dir)) == '.' or parent == dir
+            dir = parent
+            Dir.rmdir(dir)
+          end
+        rescue Errno::ENOTEMPTY, Errno::EEXIST, Errno::ENOENT
+        end
+      end
+    end
+  end
+  module_function :rmdir
+
+  # Creates {hard links}[https://en.wikipedia.org/wiki/Hard_link].
+  #
+  # Arguments +src+ (a single path or an array of paths)
+  # and +dest+ (a single path)
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # When +src+ is the path to an existing file
+  # and +dest+ is the path to a non-existent file,
+  # creates a hard link at +dest+ pointing to +src+; returns zero:
+  #
+  #   Dir.children('tmp0/')                    # => ["t.txt"]
+  #   Dir.children('tmp1/')                    # => []
+  #   Bundler::FileUtils.ln('tmp0/t.txt', 'tmp1/t.lnk') # => 0
+  #   Dir.children('tmp1/')                    # => ["t.lnk"]
+  #
+  # When +src+ is the path to an existing file
+  # and +dest+ is the path to an existing directory,
+  # creates a hard link at <tt>dest/src</tt> pointing to +src+; returns zero:
+  #
+  #   Dir.children('tmp2')               # => ["t.dat"]
+  #   Dir.children('tmp3')               # => []
+  #   Bundler::FileUtils.ln('tmp2/t.dat', 'tmp3') # => 0
+  #   Dir.children('tmp3')               # => ["t.dat"]
+  #
+  # When +src+ is an array of paths to existing files
+  # and +dest+ is the path to an existing directory,
+  # then for each path +target+ in +src+,
+  # creates a hard link at <tt>dest/target</tt> pointing to +target+;
+  # returns +src+:
+  #
+  #   Dir.children('tmp4/')                               # => []
+  #   Bundler::FileUtils.ln(['tmp0/t.txt', 'tmp2/t.dat'], 'tmp4/') # => ["tmp0/t.txt", "tmp2/t.dat"]
+  #   Dir.children('tmp4/')                               # => ["t.dat", "t.txt"]
+  #
+  # Keyword arguments:
+  #
+  # - <tt>force: true</tt> - overwrites +dest+ if it exists.
+  # - <tt>noop: true</tt> - does not create links.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     Bundler::FileUtils.ln('tmp0/t.txt', 'tmp1/t.lnk', verbose: true)
+  #     Bundler::FileUtils.ln('tmp2/t.dat', 'tmp3', verbose: true)
+  #     Bundler::FileUtils.ln(['tmp0/t.txt', 'tmp2/t.dat'], 'tmp4/', verbose: true)
+  #
+  #   Output:
+  #
+  #     ln tmp0/t.txt tmp1/t.lnk
+  #     ln tmp2/t.dat tmp3
+  #     ln tmp0/t.txt tmp2/t.dat tmp4/
+  #
+  # Raises an exception if +dest+ is the path to an existing file
+  # and keyword argument +force+ is not +true+.
+  #
+  # Related: Bundler::FileUtils.link_entry (has different options).
+  #
+  def ln(src, dest, force: nil, noop: nil, verbose: nil)
+    fu_output_message "ln#{force ? ' -f' : ''} #{[src,dest].flatten.join ' '}" if verbose
+    return if noop
+    fu_each_src_dest0(src, dest) do |s,d|
+      remove_file d, true if force
+      File.link s, d
+    end
+  end
+  module_function :ln
+
+  alias link ln
+  module_function :link
+
+  # Creates {hard links}[https://en.wikipedia.org/wiki/Hard_link].
+  #
+  # Arguments +src+ (a single path or an array of paths)
+  # and +dest+ (a single path)
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # If +src+ is the path to a directory and +dest+ does not exist,
+  # creates links +dest+ and descendents pointing to +src+ and its descendents:
+  #
+  #   tree('src0')
+  #   # => src0
+  #   #    |-- sub0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- sub1
+  #   #        |-- src2.txt
+  #   #        `-- src3.txt
+  #   File.exist?('dest0') # => false
+  #   Bundler::FileUtils.cp_lr('src0', 'dest0')
+  #   tree('dest0')
+  #   # => dest0
+  #   #    |-- sub0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- sub1
+  #   #        |-- src2.txt
+  #   #        `-- src3.txt
+  #
+  # If +src+ and +dest+ are both paths to directories,
+  # creates links <tt>dest/src</tt> and descendents
+  # pointing to +src+ and its descendents:
+  #
+  #   tree('src1')
+  #   # => src1
+  #   #    |-- sub0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- sub1
+  #   #        |-- src2.txt
+  #   #        `-- src3.txt
+  #   Bundler::FileUtils.mkdir('dest1')
+  #   Bundler::FileUtils.cp_lr('src1', 'dest1')
+  #   tree('dest1')
+  #   # => dest1
+  #   #    `-- src1
+  #   #        |-- sub0
+  #   #        |   |-- src0.txt
+  #   #        |   `-- src1.txt
+  #   #        `-- sub1
+  #   #            |-- src2.txt
+  #   #            `-- src3.txt
+  #
+  # If +src+ is an array of paths to entries and +dest+ is the path to a directory,
+  # for each path +filepath+ in +src+, creates a link at <tt>dest/filepath</tt>
+  # pointing to that path:
+  #
+  #   tree('src2')
+  #   # => src2
+  #   #    |-- sub0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- sub1
+  #   #        |-- src2.txt
+  #   #        `-- src3.txt
+  #   Bundler::FileUtils.mkdir('dest2')
+  #   Bundler::FileUtils.cp_lr(['src2/sub0', 'src2/sub1'], 'dest2')
+  #   tree('dest2')
+  #   # => dest2
+  #   #    |-- sub0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- sub1
+  #   #        |-- src2.txt
+  #   #        `-- src3.txt
+  #
+  # Keyword arguments:
+  #
+  # - <tt>dereference_root: false</tt> - if +src+ is a symbolic link,
+  #   does not dereference it.
+  # - <tt>noop: true</tt> - does not create links.
+  # - <tt>remove_destination: true</tt> - removes +dest+ before creating links.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     Bundler::FileUtils.cp_lr('src0', 'dest0', noop: true, verbose: true)
+  #     Bundler::FileUtils.cp_lr('src1', 'dest1', noop: true, verbose: true)
+  #     Bundler::FileUtils.cp_lr(['src2/sub0', 'src2/sub1'], 'dest2', noop: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     cp -lr src0 dest0
+  #     cp -lr src1 dest1
+  #     cp -lr src2/sub0 src2/sub1 dest2
+  #
+  # Raises an exception if +dest+ is the path to an existing file or directory
+  # and keyword argument <tt>remove_destination: true</tt> is not given.
+  #
+  # Related: {methods for copying}[rdoc-ref:FileUtils@Copying].
+  #
+  def cp_lr(src, dest, noop: nil, verbose: nil,
+            dereference_root: true, remove_destination: false)
+    fu_output_message "cp -lr#{remove_destination ? ' --remove-destination' : ''} #{[src,dest].flatten.join ' '}" if verbose
+    return if noop
+    fu_each_src_dest(src, dest) do |s, d|
+      link_entry s, d, dereference_root, remove_destination
+    end
+  end
+  module_function :cp_lr
+
+  # Creates {symbolic links}[https://en.wikipedia.org/wiki/Symbolic_link].
+  #
+  # Arguments +src+ (a single path or an array of paths)
+  # and +dest+ (a single path)
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # If +src+ is the path to an existing file:
+  #
+  # - When +dest+ is the path to a non-existent file,
+  #   creates a symbolic link at +dest+ pointing to +src+:
+  #
+  #     Bundler::FileUtils.touch('src0.txt')
+  #     File.exist?('dest0.txt')   # => false
+  #     Bundler::FileUtils.ln_s('src0.txt', 'dest0.txt')
+  #     File.symlink?('dest0.txt') # => true
+  #
+  # - When +dest+ is the path to an existing file,
+  #   creates a symbolic link at +dest+ pointing to +src+
+  #   if and only if keyword argument <tt>force: true</tt> is given
+  #   (raises an exception otherwise):
+  #
+  #     Bundler::FileUtils.touch('src1.txt')
+  #     Bundler::FileUtils.touch('dest1.txt')
+  #     Bundler::FileUtils.ln_s('src1.txt', 'dest1.txt', force: true)
+  #     FileTest.symlink?('dest1.txt') # => true
+  #
+  #     Bundler::FileUtils.ln_s('src1.txt', 'dest1.txt') # Raises Errno::EEXIST.
+  #
+  # If +dest+ is the path to a directory,
+  # creates a symbolic link at <tt>dest/src</tt> pointing to +src+:
+  #
+  #   Bundler::FileUtils.touch('src2.txt')
+  #   Bundler::FileUtils.mkdir('destdir2')
+  #   Bundler::FileUtils.ln_s('src2.txt', 'destdir2')
+  #   File.symlink?('destdir2/src2.txt') # => true
+  #
+  # If +src+ is an array of paths to existing files and +dest+ is a directory,
+  # for each child +child+ in +src+ creates a symbolic link <tt>dest/child</tt>
+  # pointing to +child+:
+  #
+  #   Bundler::FileUtils.mkdir('srcdir3')
+  #   Bundler::FileUtils.touch('srcdir3/src0.txt')
+  #   Bundler::FileUtils.touch('srcdir3/src1.txt')
+  #   Bundler::FileUtils.mkdir('destdir3')
+  #   Bundler::FileUtils.ln_s(['srcdir3/src0.txt', 'srcdir3/src1.txt'], 'destdir3')
+  #   File.symlink?('destdir3/src0.txt') # => true
+  #   File.symlink?('destdir3/src1.txt') # => true
+  #
+  # Keyword arguments:
+  #
+  # - <tt>force: true</tt> - overwrites +dest+ if it exists.
+  # - <tt>relative: false</tt> - create links relative to +dest+.
+  # - <tt>noop: true</tt> - does not create links.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     Bundler::FileUtils.ln_s('src0.txt', 'dest0.txt', noop: true, verbose: true)
+  #     Bundler::FileUtils.ln_s('src1.txt', 'destdir1', noop: true, verbose: true)
+  #     Bundler::FileUtils.ln_s('src2.txt', 'dest2.txt', force: true, noop: true, verbose: true)
+  #     Bundler::FileUtils.ln_s(['srcdir3/src0.txt', 'srcdir3/src1.txt'], 'destdir3', noop: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     ln -s src0.txt dest0.txt
+  #     ln -s src1.txt destdir1
+  #     ln -sf src2.txt dest2.txt
+  #     ln -s srcdir3/src0.txt srcdir3/src1.txt destdir3
+  #
+  # Related: Bundler::FileUtils.ln_sf.
+  #
+  def ln_s(src, dest, force: nil, relative: false, target_directory: true, noop: nil, verbose: nil)
+    if relative
+      return ln_sr(src, dest, force: force, target_directory: target_directory, noop: noop, verbose: verbose)
+    end
+    fu_output_message "ln -s#{force ? 'f' : ''}#{
+      target_directory ? '' : 'T'} #{[src,dest].flatten.join ' '}" if verbose
+    return if noop
+    fu_each_src_dest0(src, dest, target_directory) do |s,d|
+      remove_file d, true if force
+      File.symlink s, d
+    end
+  end
+  module_function :ln_s
+
+  alias symlink ln_s
+  module_function :symlink
+
+  # Like Bundler::FileUtils.ln_s, but always with keyword argument <tt>force: true</tt> given.
+  #
+  def ln_sf(src, dest, noop: nil, verbose: nil)
+    ln_s src, dest, force: true, noop: noop, verbose: verbose
+  end
+  module_function :ln_sf
+
+  # Like Bundler::FileUtils.ln_s, but create links relative to +dest+.
+  #
+  def ln_sr(src, dest, target_directory: true, force: nil, noop: nil, verbose: nil)
+    cmd = "ln -s#{force ? 'f' : ''}#{target_directory ? '' : 'T'}" if verbose
+    fu_each_src_dest0(src, dest, target_directory) do |s,d|
+      if target_directory
+        parent = File.dirname(d)
+        destdirs = fu_split_path(parent)
+        real_ddirs = fu_split_path(File.realpath(parent))
+      else
+        destdirs ||= fu_split_path(dest)
+        real_ddirs ||= fu_split_path(File.realdirpath(dest))
+      end
+      srcdirs = fu_split_path(s)
+      i = fu_common_components(srcdirs, destdirs)
+      n = destdirs.size - i
+      n -= 1 unless target_directory
+      link1 = fu_clean_components(*Array.new([n, 0].max, '..'), *srcdirs[i..-1])
+      begin
+        real_sdirs = fu_split_path(File.realdirpath(s)) rescue nil
+      rescue
+      else
+        i = fu_common_components(real_sdirs, real_ddirs)
+        n = real_ddirs.size - i
+        n -= 1 unless target_directory
+        link2 = fu_clean_components(*Array.new([n, 0].max, '..'), *real_sdirs[i..-1])
+        link1 = link2 if link1.size > link2.size
+      end
+      s = File.join(link1)
+      fu_output_message [cmd, s, d].flatten.join(' ') if verbose
+      next if noop
+      remove_file d, true if force
+      File.symlink s, d
+    end
+  end
+  module_function :ln_sr
+
+  # Creates {hard links}[https://en.wikipedia.org/wiki/Hard_link]; returns +nil+.
+  #
+  # Arguments +src+ and +dest+
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # If +src+ is the path to a file and +dest+ does not exist,
+  # creates a hard link at +dest+ pointing to +src+:
+  #
+  #   Bundler::FileUtils.touch('src0.txt')
+  #   File.exist?('dest0.txt') # => false
+  #   Bundler::FileUtils.link_entry('src0.txt', 'dest0.txt')
+  #   File.file?('dest0.txt')  # => true
+  #
+  # If +src+ is the path to a directory and +dest+ does not exist,
+  # recursively creates hard links at +dest+ pointing to paths in +src+:
+  #
+  #   Bundler::FileUtils.mkdir_p(['src1/dir0', 'src1/dir1'])
+  #   src_file_paths = [
+  #     'src1/dir0/t0.txt',
+  #     'src1/dir0/t1.txt',
+  #     'src1/dir1/t2.txt',
+  #     'src1/dir1/t3.txt',
+  #     ]
+  #   Bundler::FileUtils.touch(src_file_paths)
+  #   File.directory?('dest1')        # => true
+  #   Bundler::FileUtils.link_entry('src1', 'dest1')
+  #   File.file?('dest1/dir0/t0.txt') # => true
+  #   File.file?('dest1/dir0/t1.txt') # => true
+  #   File.file?('dest1/dir1/t2.txt') # => true
+  #   File.file?('dest1/dir1/t3.txt') # => true
+  #
+  # Optional arguments:
+  #
+  # - +dereference_root+ - dereferences +src+ if it is a symbolic link (+false+ by default).
+  # - +remove_destination+ - removes +dest+ before creating links (+false+ by default).
+  #
+  # Raises an exception if +dest+ is the path to an existing file or directory
+  # and optional argument +remove_destination+ is not given.
+  #
+  # Related: Bundler::FileUtils.ln (has different options).
+  #
+  def link_entry(src, dest, dereference_root = false, remove_destination = false)
+    Entry_.new(src, nil, dereference_root).traverse do |ent|
+      destent = Entry_.new(dest, ent.rel, false)
+      File.unlink destent.path if remove_destination && File.file?(destent.path)
+      ent.link destent.path
+    end
+  end
+  module_function :link_entry
+
+  # Copies files.
+  #
+  # Arguments +src+ (a single path or an array of paths)
+  # and +dest+ (a single path)
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # If +src+ is the path to a file and +dest+ is not the path to a directory,
+  # copies +src+ to +dest+:
+  #
+  #   Bundler::FileUtils.touch('src0.txt')
+  #   File.exist?('dest0.txt') # => false
+  #   Bundler::FileUtils.cp('src0.txt', 'dest0.txt')
+  #   File.file?('dest0.txt')  # => true
+  #
+  # If +src+ is the path to a file and +dest+ is the path to a directory,
+  # copies +src+ to <tt>dest/src</tt>:
+  #
+  #   Bundler::FileUtils.touch('src1.txt')
+  #   Bundler::FileUtils.mkdir('dest1')
+  #   Bundler::FileUtils.cp('src1.txt', 'dest1')
+  #   File.file?('dest1/src1.txt') # => true
+  #
+  # If +src+ is an array of paths to files and +dest+ is the path to a directory,
+  # copies from each +src+ to +dest+:
+  #
+  #   src_file_paths = ['src2.txt', 'src2.dat']
+  #   Bundler::FileUtils.touch(src_file_paths)
+  #   Bundler::FileUtils.mkdir('dest2')
+  #   Bundler::FileUtils.cp(src_file_paths, 'dest2')
+  #   File.file?('dest2/src2.txt') # => true
+  #   File.file?('dest2/src2.dat') # => true
+  #
+  # Keyword arguments:
+  #
+  # - <tt>preserve: true</tt> - preserves file times.
+  # - <tt>noop: true</tt> - does not copy files.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     Bundler::FileUtils.cp('src0.txt', 'dest0.txt', noop: true, verbose: true)
+  #     Bundler::FileUtils.cp('src1.txt', 'dest1', noop: true, verbose: true)
+  #     Bundler::FileUtils.cp(src_file_paths, 'dest2', noop: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     cp src0.txt dest0.txt
+  #     cp src1.txt dest1
+  #     cp src2.txt src2.dat dest2
+  #
+  # Raises an exception if +src+ is a directory.
+  #
+  # Related: {methods for copying}[rdoc-ref:FileUtils@Copying].
+  #
+  def cp(src, dest, preserve: nil, noop: nil, verbose: nil)
+    fu_output_message "cp#{preserve ? ' -p' : ''} #{[src,dest].flatten.join ' '}" if verbose
+    return if noop
+    fu_each_src_dest(src, dest) do |s, d|
+      copy_file s, d, preserve
+    end
+  end
+  module_function :cp
+
+  alias copy cp
+  module_function :copy
+
+  # Recursively copies files.
+  #
+  # Arguments +src+ (a single path or an array of paths)
+  # and +dest+ (a single path)
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # The mode, owner, and group are retained in the copy;
+  # to change those, use Bundler::FileUtils.install instead.
+  #
+  # If +src+ is the path to a file and +dest+ is not the path to a directory,
+  # copies +src+ to +dest+:
+  #
+  #   Bundler::FileUtils.touch('src0.txt')
+  #   File.exist?('dest0.txt') # => false
+  #   Bundler::FileUtils.cp_r('src0.txt', 'dest0.txt')
+  #   File.file?('dest0.txt')  # => true
+  #
+  # If +src+ is the path to a file and +dest+ is the path to a directory,
+  # copies +src+ to <tt>dest/src</tt>:
+  #
+  #   Bundler::FileUtils.touch('src1.txt')
+  #   Bundler::FileUtils.mkdir('dest1')
+  #   Bundler::FileUtils.cp_r('src1.txt', 'dest1')
+  #   File.file?('dest1/src1.txt') # => true
+  #
+  # If +src+ is the path to a directory and +dest+ does not exist,
+  # recursively copies +src+ to +dest+:
+  #
+  #   tree('src2')
+  #   # => src2
+  #   #    |-- dir0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- dir1
+  #   #    |-- src2.txt
+  #   #    `-- src3.txt
+  #   Bundler::FileUtils.exist?('dest2') # => false
+  #   Bundler::FileUtils.cp_r('src2', 'dest2')
+  #   tree('dest2')
+  #   # => dest2
+  #   #    |-- dir0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- dir1
+  #   #    |-- src2.txt
+  #   #    `-- src3.txt
+  #
+  # If +src+ and +dest+ are paths to directories,
+  # recursively copies +src+ to <tt>dest/src</tt>:
+  #
+  #   tree('src3')
+  #   # => src3
+  #   #    |-- dir0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- dir1
+  #   #    |-- src2.txt
+  #   #    `-- src3.txt
+  #   Bundler::FileUtils.mkdir('dest3')
+  #   Bundler::FileUtils.cp_r('src3', 'dest3')
+  #   tree('dest3')
+  #   # => dest3
+  #   #    `-- src3
+  #   #      |-- dir0
+  #   #      |   |-- src0.txt
+  #   #      |   `-- src1.txt
+  #   #      `-- dir1
+  #   #          |-- src2.txt
+  #   #          `-- src3.txt
+  #
+  # If +src+ is an array of paths and +dest+ is a directory,
+  # recursively copies from each path in +src+ to +dest+;
+  # the paths in +src+ may point to files and/or directories.
+  #
+  # Keyword arguments:
+  #
+  # - <tt>dereference_root: false</tt> - if +src+ is a symbolic link,
+  #   does not dereference it.
+  # - <tt>noop: true</tt> - does not copy files.
+  # - <tt>preserve: true</tt> - preserves file times.
+  # - <tt>remove_destination: true</tt> - removes +dest+ before copying files.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     Bundler::FileUtils.cp_r('src0.txt', 'dest0.txt', noop: true, verbose: true)
+  #     Bundler::FileUtils.cp_r('src1.txt', 'dest1', noop: true, verbose: true)
+  #     Bundler::FileUtils.cp_r('src2', 'dest2', noop: true, verbose: true)
+  #     Bundler::FileUtils.cp_r('src3', 'dest3', noop: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     cp -r src0.txt dest0.txt
+  #     cp -r src1.txt dest1
+  #     cp -r src2 dest2
+  #     cp -r src3 dest3
+  #
+  # Raises an exception of +src+ is the path to a directory
+  # and +dest+ is the path to a file.
+  #
+  # Related: {methods for copying}[rdoc-ref:FileUtils@Copying].
+  #
+  def cp_r(src, dest, preserve: nil, noop: nil, verbose: nil,
+           dereference_root: true, remove_destination: nil)
+    fu_output_message "cp -r#{preserve ? 'p' : ''}#{remove_destination ? ' --remove-destination' : ''} #{[src,dest].flatten.join ' '}" if verbose
+    return if noop
+    fu_each_src_dest(src, dest) do |s, d|
+      copy_entry s, d, preserve, dereference_root, remove_destination
+    end
+  end
+  module_function :cp_r
+
+  # Recursively copies files from +src+ to +dest+.
+  #
+  # Arguments +src+ and +dest+
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # If +src+ is the path to a file, copies +src+ to +dest+:
+  #
+  #   Bundler::FileUtils.touch('src0.txt')
+  #   File.exist?('dest0.txt') # => false
+  #   Bundler::FileUtils.copy_entry('src0.txt', 'dest0.txt')
+  #   File.file?('dest0.txt')  # => true
+  #
+  # If +src+ is a directory, recursively copies +src+ to +dest+:
+  #
+  #   tree('src1')
+  #   # => src1
+  #   #    |-- dir0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- dir1
+  #   #        |-- src2.txt
+  #   #        `-- src3.txt
+  #   Bundler::FileUtils.copy_entry('src1', 'dest1')
+  #   tree('dest1')
+  #   # => dest1
+  #   #    |-- dir0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- dir1
+  #   #        |-- src2.txt
+  #   #        `-- src3.txt
+  #
+  # The recursive copying preserves file types for regular files,
+  # directories, and symbolic links;
+  # other file types (FIFO streams, device files, etc.) are not supported.
+  #
+  # Optional arguments:
+  #
+  # - +dereference_root+ - if +src+ is a symbolic link,
+  #   follows the link (+false+ by default).
+  # - +preserve+ - preserves file times (+false+ by default).
+  # - +remove_destination+ - removes +dest+ before copying files (+false+ by default).
+  #
+  # Related: {methods for copying}[rdoc-ref:FileUtils@Copying].
+  #
+  def copy_entry(src, dest, preserve = false, dereference_root = false, remove_destination = false)
+    if dereference_root
+      src = File.realpath(src)
+    end
+
+    Entry_.new(src, nil, false).wrap_traverse(proc do |ent|
+      destent = Entry_.new(dest, ent.rel, false)
+      File.unlink destent.path if remove_destination && (File.file?(destent.path) || File.symlink?(destent.path))
+      ent.copy destent.path
+    end, proc do |ent|
+      destent = Entry_.new(dest, ent.rel, false)
+      ent.copy_metadata destent.path if preserve
+    end)
+  end
+  module_function :copy_entry
+
+  # Copies file from +src+ to +dest+, which should not be directories.
+  #
+  # Arguments +src+ and +dest+
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # Examples:
+  #
+  #   Bundler::FileUtils.touch('src0.txt')
+  #   Bundler::FileUtils.copy_file('src0.txt', 'dest0.txt')
+  #   File.file?('dest0.txt') # => true
+  #
+  # Optional arguments:
+  #
+  # - +dereference+ - if +src+ is a symbolic link,
+  #   follows the link (+true+ by default).
+  # - +preserve+ - preserves file times (+false+ by default).
+  # - +remove_destination+ - removes +dest+ before copying files (+false+ by default).
+  #
+  # Related: {methods for copying}[rdoc-ref:FileUtils@Copying].
+  #
+  def copy_file(src, dest, preserve = false, dereference = true)
+    ent = Entry_.new(src, nil, dereference)
+    ent.copy_file dest
+    ent.copy_metadata dest if preserve
+  end
+  module_function :copy_file
+
+  # Copies \IO stream +src+ to \IO stream +dest+ via
+  # {IO.copy_stream}[rdoc-ref:IO.copy_stream].
+  #
+  # Related: {methods for copying}[rdoc-ref:FileUtils@Copying].
+  #
+  def copy_stream(src, dest)
+    IO.copy_stream(src, dest)
+  end
+  module_function :copy_stream
+
+  # Moves entries.
+  #
+  # Arguments +src+ (a single path or an array of paths)
+  # and +dest+ (a single path)
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # If +src+ and +dest+ are on different file systems,
+  # first copies, then removes +src+.
+  #
+  # May cause a local vulnerability if not called with keyword argument
+  # <tt>secure: true</tt>;
+  # see {Avoiding the TOCTTOU Vulnerability}[rdoc-ref:FileUtils@Avoiding+the+TOCTTOU+Vulnerability].
+  #
+  # If +src+ is the path to a single file or directory and +dest+ does not exist,
+  # moves +src+ to +dest+:
+  #
+  #   tree('src0')
+  #   # => src0
+  #   #    |-- src0.txt
+  #   #    `-- src1.txt
+  #   File.exist?('dest0') # => false
+  #   Bundler::FileUtils.mv('src0', 'dest0')
+  #   File.exist?('src0')  # => false
+  #   tree('dest0')
+  #   # => dest0
+  #   #    |-- src0.txt
+  #   #    `-- src1.txt
+  #
+  # If +src+ is an array of paths to files and directories
+  # and +dest+ is the path to a directory,
+  # copies from each path in the array to +dest+:
+  #
+  #   File.file?('src1.txt') # => true
+  #   tree('src1')
+  #   # => src1
+  #   #    |-- src.dat
+  #   #    `-- src.txt
+  #   Dir.empty?('dest1')    # => true
+  #   Bundler::FileUtils.mv(['src1.txt', 'src1'], 'dest1')
+  #   tree('dest1')
+  #   # => dest1
+  #   #    |-- src1
+  #   #    |   |-- src.dat
+  #   #    |   `-- src.txt
+  #   #    `-- src1.txt
+  #
+  # Keyword arguments:
+  #
+  # - <tt>force: true</tt> - if the move includes removing +src+
+  #   (that is, if +src+ and +dest+ are on different file systems),
+  #   ignores raised exceptions of StandardError and its descendants.
+  # - <tt>noop: true</tt> - does not move files.
+  # - <tt>secure: true</tt> - removes +src+ securely;
+  #   see details at Bundler::FileUtils.remove_entry_secure.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     Bundler::FileUtils.mv('src0', 'dest0', noop: true, verbose: true)
+  #     Bundler::FileUtils.mv(['src1.txt', 'src1'], 'dest1', noop: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     mv src0 dest0
+  #     mv src1.txt src1 dest1
+  #
+  def mv(src, dest, force: nil, noop: nil, verbose: nil, secure: nil)
+    fu_output_message "mv#{force ? ' -f' : ''} #{[src,dest].flatten.join ' '}" if verbose
+    return if noop
+    fu_each_src_dest(src, dest) do |s, d|
+      destent = Entry_.new(d, nil, true)
+      begin
+        if destent.exist?
+          if destent.directory?
+            raise Errno::EEXIST, d
+          end
+        end
+        begin
+          File.rename s, d
+        rescue Errno::EXDEV,
+               Errno::EPERM # move from unencrypted to encrypted dir (ext4)
+          copy_entry s, d, true
+          if secure
+            remove_entry_secure s, force
+          else
+            remove_entry s, force
+          end
+        end
+      rescue SystemCallError
+        raise unless force
+      end
+    end
+  end
+  module_function :mv
+
+  alias move mv
+  module_function :move
+
+  # Removes entries at the paths in the given +list+
+  # (a single path or an array of paths)
+  # returns +list+, if it is an array, <tt>[list]</tt> otherwise.
+  #
+  # Argument +list+ or its elements
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # With no keyword arguments, removes files at the paths given in +list+:
+  #
+  #   Bundler::FileUtils.touch(['src0.txt', 'src0.dat'])
+  #   Bundler::FileUtils.rm(['src0.dat', 'src0.txt']) # => ["src0.dat", "src0.txt"]
+  #
+  # Keyword arguments:
+  #
+  # - <tt>force: true</tt> - ignores raised exceptions of StandardError
+  #   and its descendants.
+  # - <tt>noop: true</tt> - does not remove files; returns +nil+.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     Bundler::FileUtils.rm(['src0.dat', 'src0.txt'], noop: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     rm src0.dat src0.txt
+  #
+  # Related: {methods for deleting}[rdoc-ref:FileUtils@Deleting].
+  #
+  def rm(list, force: nil, noop: nil, verbose: nil)
+    list = fu_list(list)
+    fu_output_message "rm#{force ? ' -f' : ''} #{list.join ' '}" if verbose
+    return if noop
+
+    list.each do |path|
+      remove_file path, force
+    end
+  end
+  module_function :rm
+
+  alias remove rm
+  module_function :remove
+
+  # Equivalent to:
+  #
+  #   Bundler::FileUtils.rm(list, force: true, **kwargs)
+  #
+  # Argument +list+ (a single path or an array of paths)
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # See Bundler::FileUtils.rm for keyword arguments.
+  #
+  # Related: {methods for deleting}[rdoc-ref:FileUtils@Deleting].
+  #
+  def rm_f(list, noop: nil, verbose: nil)
+    rm list, force: true, noop: noop, verbose: verbose
+  end
+  module_function :rm_f
+
+  alias safe_unlink rm_f
+  module_function :safe_unlink
+
+  # Removes entries at the paths in the given +list+
+  # (a single path or an array of paths);
+  # returns +list+, if it is an array, <tt>[list]</tt> otherwise.
+  #
+  # Argument +list+ or its elements
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # May cause a local vulnerability if not called with keyword argument
+  # <tt>secure: true</tt>;
+  # see {Avoiding the TOCTTOU Vulnerability}[rdoc-ref:FileUtils@Avoiding+the+TOCTTOU+Vulnerability].
+  #
+  # For each file path, removes the file at that path:
+  #
+  #   Bundler::FileUtils.touch(['src0.txt', 'src0.dat'])
+  #   Bundler::FileUtils.rm_r(['src0.dat', 'src0.txt'])
+  #   File.exist?('src0.txt') # => false
+  #   File.exist?('src0.dat') # => false
+  #
+  # For each directory path, recursively removes files and directories:
+  #
+  #   tree('src1')
+  #   # => src1
+  #   #    |-- dir0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- dir1
+  #   #        |-- src2.txt
+  #   #        `-- src3.txt
+  #   Bundler::FileUtils.rm_r('src1')
+  #   File.exist?('src1') # => false
+  #
+  # Keyword arguments:
+  #
+  # - <tt>force: true</tt> - ignores raised exceptions of StandardError
+  #   and its descendants.
+  # - <tt>noop: true</tt> - does not remove entries; returns +nil+.
+  # - <tt>secure: true</tt> - removes +src+ securely;
+  #   see details at Bundler::FileUtils.remove_entry_secure.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     Bundler::FileUtils.rm_r(['src0.dat', 'src0.txt'], noop: true, verbose: true)
+  #     Bundler::FileUtils.rm_r('src1', noop: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     rm -r src0.dat src0.txt
+  #     rm -r src1
+  #
+  # Related: {methods for deleting}[rdoc-ref:FileUtils@Deleting].
+  #
+  def rm_r(list, force: nil, noop: nil, verbose: nil, secure: nil)
+    list = fu_list(list)
+    fu_output_message "rm -r#{force ? 'f' : ''} #{list.join ' '}" if verbose
+    return if noop
+    list.each do |path|
+      if secure
+        remove_entry_secure path, force
+      else
+        remove_entry path, force
+      end
+    end
+  end
+  module_function :rm_r
+
+  # Equivalent to:
+  #
+  #   Bundler::FileUtils.rm_r(list, force: true, **kwargs)
+  #
+  # Argument +list+ or its elements
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # May cause a local vulnerability if not called with keyword argument
+  # <tt>secure: true</tt>;
+  # see {Avoiding the TOCTTOU Vulnerability}[rdoc-ref:FileUtils@Avoiding+the+TOCTTOU+Vulnerability].
+  #
+  # See Bundler::FileUtils.rm_r for keyword arguments.
+  #
+  # Related: {methods for deleting}[rdoc-ref:FileUtils@Deleting].
+  #
+  def rm_rf(list, noop: nil, verbose: nil, secure: nil)
+    rm_r list, force: true, noop: noop, verbose: verbose, secure: secure
+  end
+  module_function :rm_rf
+
+  alias rmtree rm_rf
+  module_function :rmtree
+
+  # Securely removes the entry given by +path+,
+  # which should be the entry for a regular file, a symbolic link,
+  # or a directory.
+  #
+  # Argument +path+
+  # should be {interpretable as a path}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # Avoids a local vulnerability that can exist in certain circumstances;
+  # see {Avoiding the TOCTTOU Vulnerability}[rdoc-ref:FileUtils@Avoiding+the+TOCTTOU+Vulnerability].
+  #
+  # Optional argument +force+ specifies whether to ignore
+  # raised exceptions of StandardError and its descendants.
+  #
+  # Related: {methods for deleting}[rdoc-ref:FileUtils@Deleting].
+  #
+  def remove_entry_secure(path, force = false)
+    unless fu_have_symlink?
+      remove_entry path, force
+      return
+    end
+    fullpath = File.expand_path(path)
+    st = File.lstat(fullpath)
+    unless st.directory?
+      File.unlink fullpath
+      return
+    end
+    # is a directory.
+    parent_st = File.stat(File.dirname(fullpath))
+    unless parent_st.world_writable?
+      remove_entry path, force
+      return
+    end
+    unless parent_st.sticky?
+      raise ArgumentError, "parent directory is world writable, Bundler::FileUtils#remove_entry_secure does not work; abort: #{path.inspect} (parent directory mode #{'%o' % parent_st.mode})"
+    end
+
+    # freeze tree root
+    euid = Process.euid
+    dot_file = fullpath + "/."
+    begin
+      File.open(dot_file) {|f|
+        unless fu_stat_identical_entry?(st, f.stat)
+          # symlink (TOC-to-TOU attack?)
+          File.unlink fullpath
+          return
+        end
+        f.chown euid, -1
+        f.chmod 0700
+      }
+    rescue Errno::EISDIR # JRuby in non-native mode can't open files as dirs
+      File.lstat(dot_file).tap {|fstat|
+        unless fu_stat_identical_entry?(st, fstat)
+          # symlink (TOC-to-TOU attack?)
+          File.unlink fullpath
+          return
+        end
+        File.chown euid, -1, dot_file
+        File.chmod 0700, dot_file
+      }
+    end
+
+    unless fu_stat_identical_entry?(st, File.lstat(fullpath))
+      # TOC-to-TOU attack?
+      File.unlink fullpath
+      return
+    end
+
+    # ---- tree root is frozen ----
+    root = Entry_.new(path)
+    root.preorder_traverse do |ent|
+      if ent.directory?
+        ent.chown euid, -1
+        ent.chmod 0700
+      end
+    end
+    root.postorder_traverse do |ent|
+      begin
+        ent.remove
+      rescue
+        raise unless force
+      end
+    end
+  rescue
+    raise unless force
+  end
+  module_function :remove_entry_secure
+
+  def fu_have_symlink?   #:nodoc:
+    File.symlink nil, nil
+  rescue NotImplementedError
+    return false
+  rescue TypeError
+    return true
+  end
+  private_module_function :fu_have_symlink?
+
+  def fu_stat_identical_entry?(a, b)   #:nodoc:
+    a.dev == b.dev and a.ino == b.ino
+  end
+  private_module_function :fu_stat_identical_entry?
+
+  # Removes the entry given by +path+,
+  # which should be the entry for a regular file, a symbolic link,
+  # or a directory.
+  #
+  # Argument +path+
+  # should be {interpretable as a path}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # Optional argument +force+ specifies whether to ignore
+  # raised exceptions of StandardError and its descendants.
+  #
+  # Related: Bundler::FileUtils.remove_entry_secure.
+  #
+  def remove_entry(path, force = false)
+    Entry_.new(path).postorder_traverse do |ent|
+      begin
+        ent.remove
+      rescue
+        raise unless force
+      end
+    end
+  rescue
+    raise unless force
+  end
+  module_function :remove_entry
+
+  # Removes the file entry given by +path+,
+  # which should be the entry for a regular file or a symbolic link.
+  #
+  # Argument +path+
+  # should be {interpretable as a path}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # Optional argument +force+ specifies whether to ignore
+  # raised exceptions of StandardError and its descendants.
+  #
+  # Related: {methods for deleting}[rdoc-ref:FileUtils@Deleting].
+  #
+  def remove_file(path, force = false)
+    Entry_.new(path).remove_file
+  rescue
+    raise unless force
+  end
+  module_function :remove_file
+
+  # Recursively removes the directory entry given by +path+,
+  # which should be the entry for a regular file, a symbolic link,
+  # or a directory.
+  #
+  # Argument +path+
+  # should be {interpretable as a path}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # Optional argument +force+ specifies whether to ignore
+  # raised exceptions of StandardError and its descendants.
+  #
+  # Related: {methods for deleting}[rdoc-ref:FileUtils@Deleting].
+  #
+  def remove_dir(path, force = false)
+    raise Errno::ENOTDIR, path unless force or File.directory?(path)
+    remove_entry path, force
+  end
+  module_function :remove_dir
+
+  # Returns +true+ if the contents of files +a+ and +b+ are identical,
+  # +false+ otherwise.
+  #
+  # Arguments +a+ and +b+
+  # should be {interpretable as a path}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # Bundler::FileUtils.identical? and Bundler::FileUtils.cmp are aliases for Bundler::FileUtils.compare_file.
+  #
+  # Related: Bundler::FileUtils.compare_stream.
+  #
+  def compare_file(a, b)
+    return false unless File.size(a) == File.size(b)
+    File.open(a, 'rb') {|fa|
+      File.open(b, 'rb') {|fb|
+        return compare_stream(fa, fb)
+      }
+    }
+  end
+  module_function :compare_file
+
+  alias identical? compare_file
+  alias cmp compare_file
+  module_function :identical?
+  module_function :cmp
+
+  # Returns +true+ if the contents of streams +a+ and +b+ are identical,
+  # +false+ otherwise.
+  #
+  # Arguments +a+ and +b+
+  # should be {interpretable as a path}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # Related: Bundler::FileUtils.compare_file.
+  #
+  def compare_stream(a, b)
+    bsize = fu_stream_blksize(a, b)
+
+    sa = String.new(capacity: bsize)
+    sb = String.new(capacity: bsize)
+
+    begin
+      a.read(bsize, sa)
+      b.read(bsize, sb)
+      return true if sa.empty? && sb.empty?
+    end while sa == sb
+    false
+  end
+  module_function :compare_stream
+
+  # Copies a file entry.
+  # See {install(1)}[https://man7.org/linux/man-pages/man1/install.1.html].
+  #
+  # Arguments +src+ (a single path or an array of paths)
+  # and +dest+ (a single path)
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments];
+  #
+  # If the entry at +dest+ does not exist, copies from +src+ to +dest+:
+  #
+  #   File.read('src0.txt')    # => "aaa\n"
+  #   File.exist?('dest0.txt') # => false
+  #   Bundler::FileUtils.install('src0.txt', 'dest0.txt')
+  #   File.read('dest0.txt')   # => "aaa\n"
+  #
+  # If +dest+ is a file entry, copies from +src+ to +dest+, overwriting:
+  #
+  #   File.read('src1.txt')  # => "aaa\n"
+  #   File.read('dest1.txt') # => "bbb\n"
+  #   Bundler::FileUtils.install('src1.txt', 'dest1.txt')
+  #   File.read('dest1.txt') # => "aaa\n"
+  #
+  # If +dest+ is a directory entry, copies from +src+ to <tt>dest/src</tt>,
+  # overwriting if necessary:
+  #
+  #   File.read('src2.txt')       # => "aaa\n"
+  #   File.read('dest2/src2.txt') # => "bbb\n"
+  #   Bundler::FileUtils.install('src2.txt', 'dest2')
+  #   File.read('dest2/src2.txt') # => "aaa\n"
+  #
+  # If +src+ is an array of paths and +dest+ points to a directory,
+  # copies each path +path+ in +src+ to <tt>dest/path</tt>:
+  #
+  #   File.file?('src3.txt') # => true
+  #   File.file?('src3.dat') # => true
+  #   Bundler::FileUtils.mkdir('dest3')
+  #   Bundler::FileUtils.install(['src3.txt', 'src3.dat'], 'dest3')
+  #   File.file?('dest3/src3.txt') # => true
+  #   File.file?('dest3/src3.dat') # => true
+  #
+  # Keyword arguments:
+  #
+  # - <tt>group: <i>group</i></tt> - changes the group if not +nil+,
+  #   using {File.chown}[rdoc-ref:File.chown].
+  # - <tt>mode: <i>permissions</i></tt> - changes the permissions.
+  #   using {File.chmod}[rdoc-ref:File.chmod].
+  # - <tt>noop: true</tt> - does not copy entries; returns +nil+.
+  # - <tt>owner: <i>owner</i></tt> - changes the owner if not +nil+,
+  #   using {File.chown}[rdoc-ref:File.chown].
+  # - <tt>preserve: true</tt> - preserve timestamps
+  #   using {File.utime}[rdoc-ref:File.utime].
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     Bundler::FileUtils.install('src0.txt', 'dest0.txt', noop: true, verbose: true)
+  #     Bundler::FileUtils.install('src1.txt', 'dest1.txt', noop: true, verbose: true)
+  #     Bundler::FileUtils.install('src2.txt', 'dest2', noop: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     install -c src0.txt dest0.txt
+  #     install -c src1.txt dest1.txt
+  #     install -c src2.txt dest2
+  #
+  # Related: {methods for copying}[rdoc-ref:FileUtils@Copying].
+  #
+  def install(src, dest, mode: nil, owner: nil, group: nil, preserve: nil,
+              noop: nil, verbose: nil)
+    if verbose
+      msg = +"install -c"
+      msg << ' -p' if preserve
+      msg << ' -m ' << mode_to_s(mode) if mode
+      msg << " -o #{owner}" if owner
+      msg << " -g #{group}" if group
+      msg << ' ' << [src,dest].flatten.join(' ')
+      fu_output_message msg
+    end
+    return if noop
+    uid = fu_get_uid(owner)
+    gid = fu_get_gid(group)
+    fu_each_src_dest(src, dest) do |s, d|
+      st = File.stat(s)
+      unless File.exist?(d) and compare_file(s, d)
+        remove_file d, true
+        if d.end_with?('/')
+          mkdir_p d
+          copy_file s, d + File.basename(s)
+        else
+          mkdir_p File.expand_path('..', d)
+          copy_file s, d
+        end
+        File.utime st.atime, st.mtime, d if preserve
+        File.chmod fu_mode(mode, st), d if mode
+        File.chown uid, gid, d if uid or gid
+      end
+    end
+  end
+  module_function :install
+
+  def user_mask(target)  #:nodoc:
+    target.each_char.inject(0) do |mask, chr|
+      case chr
+      when "u"
+        mask | 04700
+      when "g"
+        mask | 02070
+      when "o"
+        mask | 01007
+      when "a"
+        mask | 07777
+      else
+        raise ArgumentError, "invalid 'who' symbol in file mode: #{chr}"
+      end
+    end
+  end
+  private_module_function :user_mask
+
+  def apply_mask(mode, user_mask, op, mode_mask)   #:nodoc:
+    case op
+    when '='
+      (mode & ~user_mask) | (user_mask & mode_mask)
+    when '+'
+      mode | (user_mask & mode_mask)
+    when '-'
+      mode & ~(user_mask & mode_mask)
+    end
+  end
+  private_module_function :apply_mask
+
+  def symbolic_modes_to_i(mode_sym, path)  #:nodoc:
+    path = File.stat(path) unless File::Stat === path
+    mode = path.mode
+    mode_sym.split(/,/).inject(mode & 07777) do |current_mode, clause|
+      target, *actions = clause.split(/([=+-])/)
+      raise ArgumentError, "invalid file mode: #{mode_sym}" if actions.empty?
+      target = 'a' if target.empty?
+      user_mask = user_mask(target)
+      actions.each_slice(2) do |op, perm|
+        need_apply = op == '='
+        mode_mask = (perm || '').each_char.inject(0) do |mask, chr|
+          case chr
+          when "r"
+            mask | 0444
+          when "w"
+            mask | 0222
+          when "x"
+            mask | 0111
+          when "X"
+            if path.directory?
+              mask | 0111
+            else
+              mask
+            end
+          when "s"
+            mask | 06000
+          when "t"
+            mask | 01000
+          when "u", "g", "o"
+            if mask.nonzero?
+              current_mode = apply_mask(current_mode, user_mask, op, mask)
+            end
+            need_apply = false
+            copy_mask = user_mask(chr)
+            (current_mode & copy_mask) / (copy_mask & 0111) * (user_mask & 0111)
+          else
+            raise ArgumentError, "invalid 'perm' symbol in file mode: #{chr}"
+          end
+        end
+
+        if mode_mask.nonzero? || need_apply
+          current_mode = apply_mask(current_mode, user_mask, op, mode_mask)
+        end
+      end
+      current_mode
+    end
+  end
+  private_module_function :symbolic_modes_to_i
+
+  def fu_mode(mode, path)  #:nodoc:
+    mode.is_a?(String) ? symbolic_modes_to_i(mode, path) : mode
+  end
+  private_module_function :fu_mode
+
+  def mode_to_s(mode)  #:nodoc:
+    mode.is_a?(String) ? mode : "%o" % mode
+  end
+  private_module_function :mode_to_s
+
+  # Changes permissions on the entries at the paths given in +list+
+  # (a single path or an array of paths)
+  # to the permissions given by +mode+;
+  # returns +list+ if it is an array, <tt>[list]</tt> otherwise:
+  #
+  # - Modifies each entry that is a regular file using
+  #   {File.chmod}[rdoc-ref:File.chmod].
+  # - Modifies each entry that is a symbolic link using
+  #   {File.lchmod}[rdoc-ref:File.lchmod].
+  #
+  # Argument +list+ or its elements
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # Argument +mode+ may be either an integer or a string:
+  #
+  # - \Integer +mode+: represents the permission bits to be set:
+  #
+  #     Bundler::FileUtils.chmod(0755, 'src0.txt')
+  #     Bundler::FileUtils.chmod(0644, ['src0.txt', 'src0.dat'])
+  #
+  # - \String +mode+: represents the permissions to be set:
+  #
+  #   The string is of the form <tt>[targets][[operator][perms[,perms]]</tt>, where:
+  #
+  #   - +targets+ may be any combination of these letters:
+  #
+  #     - <tt>'u'</tt>: permissions apply to the file's owner.
+  #     - <tt>'g'</tt>: permissions apply to users in the file's group.
+  #     - <tt>'o'</tt>: permissions apply to other users not in the file's group.
+  #     - <tt>'a'</tt> (the default): permissions apply to all users.
+  #
+  #   - +operator+ may be one of these letters:
+  #
+  #     - <tt>'+'</tt>: adds permissions.
+  #     - <tt>'-'</tt>: removes permissions.
+  #     - <tt>'='</tt>: sets (replaces) permissions.
+  #
+  #   - +perms+ (may be repeated, with separating commas)
+  #     may be any combination of these letters:
+  #
+  #     - <tt>'r'</tt>: Read.
+  #     - <tt>'w'</tt>: Write.
+  #     - <tt>'x'</tt>: Execute (search, for a directory).
+  #     - <tt>'X'</tt>: Search (for a directories only;
+  #       must be used with <tt>'+'</tt>)
+  #     - <tt>'s'</tt>: Uid or gid.
+  #     - <tt>'t'</tt>: Sticky bit.
+  #
+  #   Examples:
+  #
+  #     Bundler::FileUtils.chmod('u=wrx,go=rx', 'src1.txt')
+  #     Bundler::FileUtils.chmod('u=wrx,go=rx', '/usr/bin/ruby')
+  #
+  # Keyword arguments:
+  #
+  # - <tt>noop: true</tt> - does not change permissions; returns +nil+.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     Bundler::FileUtils.chmod(0755, 'src0.txt', noop: true, verbose: true)
+  #     Bundler::FileUtils.chmod(0644, ['src0.txt', 'src0.dat'], noop: true, verbose: true)
+  #     Bundler::FileUtils.chmod('u=wrx,go=rx', 'src1.txt', noop: true, verbose: true)
+  #     Bundler::FileUtils.chmod('u=wrx,go=rx', '/usr/bin/ruby', noop: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     chmod 755 src0.txt
+  #     chmod 644 src0.txt src0.dat
+  #     chmod u=wrx,go=rx src1.txt
+  #     chmod u=wrx,go=rx /usr/bin/ruby
+  #
+  # Related: Bundler::FileUtils.chmod_R.
+  #
+  def chmod(mode, list, noop: nil, verbose: nil)
+    list = fu_list(list)
+    fu_output_message sprintf('chmod %s %s', mode_to_s(mode), list.join(' ')) if verbose
+    return if noop
+    list.each do |path|
+      Entry_.new(path).chmod(fu_mode(mode, path))
+    end
+  end
+  module_function :chmod
+
+  # Like Bundler::FileUtils.chmod, but changes permissions recursively.
+  #
+  def chmod_R(mode, list, noop: nil, verbose: nil, force: nil)
+    list = fu_list(list)
+    fu_output_message sprintf('chmod -R%s %s %s',
+                              (force ? 'f' : ''),
+                              mode_to_s(mode), list.join(' ')) if verbose
+    return if noop
+    list.each do |root|
+      Entry_.new(root).traverse do |ent|
+        begin
+          ent.chmod(fu_mode(mode, ent.path))
+        rescue
+          raise unless force
+        end
+      end
+    end
+  end
+  module_function :chmod_R
+
+  # Changes the owner and group on the entries at the paths given in +list+
+  # (a single path or an array of paths)
+  # to the given +user+ and +group+;
+  # returns +list+ if it is an array, <tt>[list]</tt> otherwise:
+  #
+  # - Modifies each entry that is a regular file using
+  #   {File.chown}[rdoc-ref:File.chown].
+  # - Modifies each entry that is a symbolic link using
+  #   {File.lchown}[rdoc-ref:File.lchown].
+  #
+  # Argument +list+ or its elements
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # User and group:
+  #
+  # - Argument +user+ may be a user name or a user id;
+  #   if +nil+ or +-1+, the user is not changed.
+  # - Argument +group+ may be a group name or a group id;
+  #   if +nil+ or +-1+, the group is not changed.
+  # - The user must be a member of the group.
+  #
+  # Examples:
+  #
+  #   # One path.
+  #   # User and group as string names.
+  #   File.stat('src0.txt').uid # => 1004
+  #   File.stat('src0.txt').gid # => 1004
+  #   Bundler::FileUtils.chown('user2', 'group1', 'src0.txt')
+  #   File.stat('src0.txt').uid # => 1006
+  #   File.stat('src0.txt').gid # => 1005
+  #
+  #   # User and group as uid and gid.
+  #   Bundler::FileUtils.chown(1004, 1004, 'src0.txt')
+  #   File.stat('src0.txt').uid # => 1004
+  #   File.stat('src0.txt').gid # => 1004
+  #
+  #   # Array of paths.
+  #   Bundler::FileUtils.chown(1006, 1005, ['src0.txt', 'src0.dat'])
+  #
+  #   # Directory (not recursive).
+  #   Bundler::FileUtils.chown('user2', 'group1', '.')
+  #
+  # Keyword arguments:
+  #
+  # - <tt>noop: true</tt> - does not change permissions; returns +nil+.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     Bundler::FileUtils.chown('user2', 'group1', 'src0.txt', noop: true, verbose: true)
+  #     Bundler::FileUtils.chown(1004, 1004, 'src0.txt', noop: true, verbose: true)
+  #     Bundler::FileUtils.chown(1006, 1005, ['src0.txt', 'src0.dat'], noop: true, verbose: true)
+  #     Bundler::FileUtils.chown('user2', 'group1', path, noop: true, verbose: true)
+  #     Bundler::FileUtils.chown('user2', 'group1', '.', noop: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     chown user2:group1 src0.txt
+  #     chown 1004:1004 src0.txt
+  #     chown 1006:1005 src0.txt src0.dat
+  #     chown user2:group1 src0.txt
+  #     chown user2:group1 .
+  #
+  # Related: Bundler::FileUtils.chown_R.
+  #
+  def chown(user, group, list, noop: nil, verbose: nil)
+    list = fu_list(list)
+    fu_output_message sprintf('chown %s %s',
+                              (group ? "#{user}:#{group}" : user || ':'),
+                              list.join(' ')) if verbose
+    return if noop
+    uid = fu_get_uid(user)
+    gid = fu_get_gid(group)
+    list.each do |path|
+      Entry_.new(path).chown uid, gid
+    end
+  end
+  module_function :chown
+
+  # Like Bundler::FileUtils.chown, but changes owner and group recursively.
+  #
+  def chown_R(user, group, list, noop: nil, verbose: nil, force: nil)
+    list = fu_list(list)
+    fu_output_message sprintf('chown -R%s %s %s',
+                              (force ? 'f' : ''),
+                              (group ? "#{user}:#{group}" : user || ':'),
+                              list.join(' ')) if verbose
+    return if noop
+    uid = fu_get_uid(user)
+    gid = fu_get_gid(group)
+    list.each do |root|
+      Entry_.new(root).traverse do |ent|
+        begin
+          ent.chown uid, gid
+        rescue
+          raise unless force
+        end
+      end
+    end
+  end
+  module_function :chown_R
+
+  def fu_get_uid(user)   #:nodoc:
+    return nil unless user
+    case user
+    when Integer
+      user
+    when /\A\d+\z/
+      user.to_i
+    else
+      require 'etc'
+      Etc.getpwnam(user) ? Etc.getpwnam(user).uid : nil
+    end
+  end
+  private_module_function :fu_get_uid
+
+  def fu_get_gid(group)   #:nodoc:
+    return nil unless group
+    case group
+    when Integer
+      group
+    when /\A\d+\z/
+      group.to_i
+    else
+      require 'etc'
+      Etc.getgrnam(group) ? Etc.getgrnam(group).gid : nil
+    end
+  end
+  private_module_function :fu_get_gid
+
+  # Updates modification times (mtime) and access times (atime)
+  # of the entries given by the paths in +list+
+  # (a single path or an array of paths);
+  # returns +list+ if it is an array, <tt>[list]</tt> otherwise.
+  #
+  # By default, creates an empty file for any path to a non-existent entry;
+  # use keyword argument +nocreate+ to raise an exception instead.
+  #
+  # Argument +list+ or its elements
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # Examples:
+  #
+  #   # Single path.
+  #   f = File.new('src0.txt') # Existing file.
+  #   f.atime # => 2022-06-10 11:11:21.200277 -0700
+  #   f.mtime # => 2022-06-10 11:11:21.200277 -0700
+  #   Bundler::FileUtils.touch('src0.txt')
+  #   f = File.new('src0.txt')
+  #   f.atime # => 2022-06-11 08:28:09.8185343 -0700
+  #   f.mtime # => 2022-06-11 08:28:09.8185343 -0700
+  #
+  #   # Array of paths.
+  #   Bundler::FileUtils.touch(['src0.txt', 'src0.dat'])
+  #
+  # Keyword arguments:
+  #
+  # - <tt>mtime: <i>time</i></tt> - sets the entry's mtime to the given time,
+  #   instead of the current time.
+  # - <tt>nocreate: true</tt> - raises an exception if the entry does not exist.
+  # - <tt>noop: true</tt> - does not touch entries; returns +nil+.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     Bundler::FileUtils.touch('src0.txt', noop: true, verbose: true)
+  #     Bundler::FileUtils.touch(['src0.txt', 'src0.dat'], noop: true, verbose: true)
+  #     Bundler::FileUtils.touch(path, noop: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     touch src0.txt
+  #     touch src0.txt src0.dat
+  #     touch src0.txt
+  #
+  # Related: Bundler::FileUtils.uptodate?.
+  #
+  def touch(list, noop: nil, verbose: nil, mtime: nil, nocreate: nil)
+    list = fu_list(list)
+    t = mtime
+    if verbose
+      fu_output_message "touch #{nocreate ? '-c ' : ''}#{t ? t.strftime('-t %Y%m%d%H%M.%S ') : ''}#{list.join ' '}"
+    end
+    return if noop
+    list.each do |path|
+      created = nocreate
+      begin
+        File.utime(t, t, path)
+      rescue Errno::ENOENT
+        raise if created
+        File.open(path, 'a') {
+          ;
+        }
+        created = true
+        retry if t
+      end
+    end
+  end
+  module_function :touch
+
+  private
+
+  module StreamUtils_ # :nodoc:
+
+    private
+
+    case (defined?(::RbConfig) ? ::RbConfig::CONFIG['host_os'] : ::RUBY_PLATFORM)
+    when /mswin|mingw/
+      def fu_windows?; true end #:nodoc:
+    else
+      def fu_windows?; false end #:nodoc:
+    end
+
+    def fu_copy_stream0(src, dest, blksize = nil)   #:nodoc:
+      IO.copy_stream(src, dest)
+    end
+
+    def fu_stream_blksize(*streams) #:nodoc:
+      streams.each do |s|
+        next unless s.respond_to?(:stat)
+        size = fu_blksize(s.stat)
+        return size if size
+      end
+      fu_default_blksize()
+    end
+
+    def fu_blksize(st) #:nodoc:
+      s = st.blksize
+      return nil unless s
+      return nil if s == 0
+      s
+    end
+
+    def fu_default_blksize #:nodoc:
+      1024
+    end
+  end
+
+  include StreamUtils_
+  extend StreamUtils_
+
+  class Entry_   #:nodoc: internal use only
+    include StreamUtils_
+
+    def initialize(a, b = nil, deref = false)
+      @prefix = @rel = @path = nil
+      if b
+        @prefix = a
+        @rel = b
+      else
+        @path = a
+      end
+      @deref = deref
+      @stat = nil
+      @lstat = nil
+    end
+
+    def inspect
+      "\#<#{self.class} #{path()}>"
+    end
+
+    def path
+      if @path
+        File.path(@path)
+      else
+        join(@prefix, @rel)
+      end
+    end
+
+    def prefix
+      @prefix || @path
+    end
+
+    def rel
+      @rel
+    end
+
+    def dereference?
+      @deref
+    end
+
+    def exist?
+      begin
+        lstat
+        true
+      rescue Errno::ENOENT
+        false
+      end
+    end
+
+    def file?
+      s = lstat!
+      s and s.file?
+    end
+
+    def directory?
+      s = lstat!
+      s and s.directory?
+    end
+
+    def symlink?
+      s = lstat!
+      s and s.symlink?
+    end
+
+    def chardev?
+      s = lstat!
+      s and s.chardev?
+    end
+
+    def blockdev?
+      s = lstat!
+      s and s.blockdev?
+    end
+
+    def socket?
+      s = lstat!
+      s and s.socket?
+    end
+
+    def pipe?
+      s = lstat!
+      s and s.pipe?
+    end
+
+    S_IF_DOOR = 0xD000
+
+    def door?
+      s = lstat!
+      s and (s.mode & 0xF000 == S_IF_DOOR)
+    end
+
+    def entries
+      opts = {}
+      opts[:encoding] = fu_windows? ? ::Encoding::UTF_8 : path.encoding
+
+      files = Dir.children(path, **opts)
+
+      untaint = RUBY_VERSION < '2.7'
+      files.map {|n| Entry_.new(prefix(), join(rel(), untaint ? n.untaint : n)) }
+    end
+
+    def stat
+      return @stat if @stat
+      if lstat() and lstat().symlink?
+        @stat = File.stat(path())
+      else
+        @stat = lstat()
+      end
+      @stat
+    end
+
+    def stat!
+      return @stat if @stat
+      if lstat! and lstat!.symlink?
+        @stat = File.stat(path())
+      else
+        @stat = lstat!
+      end
+      @stat
+    rescue SystemCallError
+      nil
+    end
+
+    def lstat
+      if dereference?
+        @lstat ||= File.stat(path())
+      else
+        @lstat ||= File.lstat(path())
+      end
+    end
+
+    def lstat!
+      lstat()
+    rescue SystemCallError
+      nil
+    end
+
+    def chmod(mode)
+      if symlink?
+        File.lchmod mode, path() if have_lchmod?
+      else
+        File.chmod mode, path()
+      end
+    rescue Errno::EOPNOTSUPP
+    end
+
+    def chown(uid, gid)
+      if symlink?
+        File.lchown uid, gid, path() if have_lchown?
+      else
+        File.chown uid, gid, path()
+      end
+    end
+
+    def link(dest)
+      case
+      when directory?
+        if !File.exist?(dest) and descendant_directory?(dest, path)
+          raise ArgumentError, "cannot link directory %s to itself %s" % [path, dest]
+        end
+        begin
+          Dir.mkdir dest
+        rescue
+          raise unless File.directory?(dest)
+        end
+      else
+        File.link path(), dest
+      end
+    end
+
+    def copy(dest)
+      lstat
+      case
+      when file?
+        copy_file dest
+      when directory?
+        if !File.exist?(dest) and descendant_directory?(dest, path)
+          raise ArgumentError, "cannot copy directory %s to itself %s" % [path, dest]
+        end
+        begin
+          Dir.mkdir dest
+        rescue
+          raise unless File.directory?(dest)
+        end
+      when symlink?
+        File.symlink File.readlink(path()), dest
+      when chardev?, blockdev?
+        raise "cannot handle device file"
+      when socket?
+        begin
+          require 'socket'
+        rescue LoadError
+          raise "cannot handle socket"
+        else
+          raise "cannot handle socket" unless defined?(UNIXServer)
+        end
+        UNIXServer.new(dest).close
+        File.chmod lstat().mode, dest
+      when pipe?
+        raise "cannot handle FIFO" unless File.respond_to?(:mkfifo)
+        File.mkfifo dest, lstat().mode
+      when door?
+        raise "cannot handle door: #{path()}"
+      else
+        raise "unknown file type: #{path()}"
+      end
+    end
+
+    def copy_file(dest)
+      File.open(path()) do |s|
+        File.open(dest, 'wb', s.stat.mode) do |f|
+          IO.copy_stream(s, f)
+        end
+      end
+    end
+
+    def copy_metadata(path)
+      st = lstat()
+      if !st.symlink?
+        File.utime st.atime, st.mtime, path
+      end
+      mode = st.mode
+      begin
+        if st.symlink?
+          begin
+            File.lchown st.uid, st.gid, path
+          rescue NotImplementedError
+          end
+        else
+          File.chown st.uid, st.gid, path
+        end
+      rescue Errno::EPERM, Errno::EACCES
+        # clear setuid/setgid
+        mode &= 01777
+      end
+      if st.symlink?
+        begin
+          File.lchmod mode, path
+        rescue NotImplementedError, Errno::EOPNOTSUPP
+        end
+      else
+        File.chmod mode, path
+      end
+    end
+
+    def remove
+      if directory?
+        remove_dir1
+      else
+        remove_file
+      end
+    end
+
+    def remove_dir1
+      platform_support {
+        Dir.rmdir path().chomp(?/)
+      }
+    end
+
+    def remove_file
+      platform_support {
+        File.unlink path
+      }
+    end
+
+    def platform_support
+      return yield unless fu_windows?
+      first_time_p = true
+      begin
+        yield
+      rescue Errno::ENOENT
+        raise
+      rescue => err
+        if first_time_p
+          first_time_p = false
+          begin
+            File.chmod 0700, path()   # Windows does not have symlink
+            retry
+          rescue SystemCallError
+          end
+        end
+        raise err
+      end
+    end
+
+    def preorder_traverse
+      stack = [self]
+      while ent = stack.pop
+        yield ent
+        stack.concat ent.entries.reverse if ent.directory?
+      end
+    end
+
+    alias traverse preorder_traverse
+
+    def postorder_traverse
+      if directory?
+        begin
+          children = entries()
+        rescue Errno::EACCES
+          # Failed to get the list of children.
+          # Assuming there is no children, try to process the parent directory.
+          yield self
+          return
+        end
+
+        children.each do |ent|
+          ent.postorder_traverse do |e|
+            yield e
+          end
+        end
+      end
+      yield self
+    end
+
+    def wrap_traverse(pre, post)
+      pre.call self
+      if directory?
+        entries.each do |ent|
+          ent.wrap_traverse pre, post
+        end
+      end
+      post.call self
+    end
+
+    private
+
+    @@fileutils_rb_have_lchmod = nil
+
+    def have_lchmod?
+      # This is not MT-safe, but it does not matter.
+      if @@fileutils_rb_have_lchmod == nil
+        @@fileutils_rb_have_lchmod = check_have_lchmod?
+      end
+      @@fileutils_rb_have_lchmod
+    end
+
+    def check_have_lchmod?
+      return false unless File.respond_to?(:lchmod)
+      File.lchmod 0
+      return true
+    rescue NotImplementedError
+      return false
+    end
+
+    @@fileutils_rb_have_lchown = nil
+
+    def have_lchown?
+      # This is not MT-safe, but it does not matter.
+      if @@fileutils_rb_have_lchown == nil
+        @@fileutils_rb_have_lchown = check_have_lchown?
+      end
+      @@fileutils_rb_have_lchown
+    end
+
+    def check_have_lchown?
+      return false unless File.respond_to?(:lchown)
+      File.lchown nil, nil
+      return true
+    rescue NotImplementedError
+      return false
+    end
+
+    def join(dir, base)
+      return File.path(dir) if not base or base == '.'
+      return File.path(base) if not dir or dir == '.'
+      begin
+        File.join(dir, base)
+      rescue EncodingError
+        if fu_windows?
+          File.join(dir.encode(::Encoding::UTF_8), base.encode(::Encoding::UTF_8))
+        else
+          raise
+        end
+      end
+    end
+
+    if File::ALT_SEPARATOR
+      DIRECTORY_TERM = "(?=[/#{Regexp.quote(File::ALT_SEPARATOR)}]|\\z)"
+    else
+      DIRECTORY_TERM = "(?=/|\\z)"
+    end
+
+    def descendant_directory?(descendant, ascendant)
+      if File::FNM_SYSCASE.nonzero?
+        File.expand_path(File.dirname(descendant)).casecmp(File.expand_path(ascendant)) == 0
+      else
+        File.expand_path(File.dirname(descendant)) == File.expand_path(ascendant)
+      end
+    end
+  end   # class Entry_
+
+  def fu_list(arg)   #:nodoc:
+    [arg].flatten.map {|path| File.path(path) }
+  end
+  private_module_function :fu_list
+
+  def fu_each_src_dest(src, dest)   #:nodoc:
+    fu_each_src_dest0(src, dest) do |s, d|
+      raise ArgumentError, "same file: #{s} and #{d}" if fu_same?(s, d)
+      yield s, d
+    end
+  end
+  private_module_function :fu_each_src_dest
+
+  def fu_each_src_dest0(src, dest, target_directory = true)   #:nodoc:
+    if tmp = Array.try_convert(src)
+      unless target_directory or tmp.size <= 1
+        tmp = tmp.map {|f| File.path(f)} # A workaround for RBS
+        raise ArgumentError, "extra target #{tmp}"
+      end
+      tmp.each do |s|
+        s = File.path(s)
+        yield s, (target_directory ? File.join(dest, File.basename(s)) : dest)
+      end
+    else
+      src = File.path(src)
+      if target_directory and File.directory?(dest)
+        yield src, File.join(dest, File.basename(src))
+      else
+        yield src, File.path(dest)
+      end
+    end
+  end
+  private_module_function :fu_each_src_dest0
+
+  def fu_same?(a, b)   #:nodoc:
+    File.identical?(a, b)
+  end
+  private_module_function :fu_same?
+
+  def fu_output_message(msg)   #:nodoc:
+    output = @fileutils_output if defined?(@fileutils_output)
+    output ||= $stdout
+    if defined?(@fileutils_label)
+      msg = @fileutils_label + msg
+    end
+    output.puts msg
+  end
+  private_module_function :fu_output_message
+
+  def fu_split_path(path) #:nodoc:
+    path = File.path(path)
+    list = []
+    until (parent, base = File.split(path); parent == path or parent == ".")
+      if base != '..' and list.last == '..' and !(fu_have_symlink? && File.symlink?(path))
+        list.pop
+      else
+        list << base
+      end
+      path = parent
+    end
+    list << path
+    list.reverse!
+  end
+  private_module_function :fu_split_path
+
+  def fu_common_components(target, base) #:nodoc:
+    i = 0
+    while target[i]&.== base[i]
+      i += 1
+    end
+    i
+  end
+  private_module_function :fu_common_components
+
+  def fu_clean_components(*comp) #:nodoc:
+    comp.shift while comp.first == "."
+    return comp if comp.empty?
+    clean = [comp.shift]
+    path = File.join(*clean, "") # ending with File::SEPARATOR
+    while c = comp.shift
+      if c == ".." and clean.last != ".." and !(fu_have_symlink? && File.symlink?(path))
+        clean.pop
+        path.sub!(%r((?<=\A|/)[^/]+/\z), "")
+      else
+        clean << c
+        path << c << "/"
+      end
+    end
+    clean
+  end
+  private_module_function :fu_clean_components
+
+  if fu_windows?
+    def fu_starting_path?(path) #:nodoc:
+      path&.start_with?(%r(\w:|/))
+    end
+  else
+    def fu_starting_path?(path) #:nodoc:
+      path&.start_with?("/")
+    end
+  end
+  private_module_function :fu_starting_path?
+
+  # This hash table holds command options.
+  OPT_TABLE = {}    #:nodoc: internal use only
+  (private_instance_methods & methods(false)).inject(OPT_TABLE) {|tbl, name|
+    (tbl[name.to_s] = instance_method(name).parameters).map! {|t, n| n if t == :key}.compact!
+    tbl
+  }
+
+  public
+
+  # Returns an array of the string names of \Bundler::FileUtils methods
+  # that accept one or more keyword arguments:
+  #
+  #   Bundler::FileUtils.commands.sort.take(3) # => ["cd", "chdir", "chmod"]
+  #
+  def self.commands
+    OPT_TABLE.keys
+  end
+
+  # Returns an array of the string keyword names:
+  #
+  #   Bundler::FileUtils.options.take(3) # => ["noop", "verbose", "force"]
+  #
+  def self.options
+    OPT_TABLE.values.flatten.uniq.map {|sym| sym.to_s }
+  end
+
+  # Returns +true+ if method +mid+ accepts the given option +opt+, +false+ otherwise;
+  # the arguments may be strings or symbols:
+  #
+  #   Bundler::FileUtils.have_option?(:chmod, :noop) # => true
+  #   Bundler::FileUtils.have_option?('chmod', 'secure') # => false
+  #
+  def self.have_option?(mid, opt)
+    li = OPT_TABLE[mid.to_s] or raise ArgumentError, "no such method: #{mid}"
+    li.include?(opt)
+  end
+
+  # Returns an array of the string keyword name for method +mid+;
+  # the argument may be a string or a symbol:
+  #
+  #   Bundler::FileUtils.options_of(:rm) # => ["force", "noop", "verbose"]
+  #   Bundler::FileUtils.options_of('mv') # => ["force", "noop", "verbose", "secure"]
+  #
+  def self.options_of(mid)
+    OPT_TABLE[mid.to_s].map {|sym| sym.to_s }
+  end
+
+  # Returns an array of the string method names of the methods
+  # that accept the given keyword option +opt+;
+  # the argument must be a symbol:
+  #
+  #   Bundler::FileUtils.collect_method(:preserve) # => ["cp", "copy", "cp_r", "install"]
+  #
+  def self.collect_method(opt)
+    OPT_TABLE.keys.select {|m| OPT_TABLE[m].include?(opt) }
+  end
+
+  private
+
+  LOW_METHODS = singleton_methods(false) - collect_method(:noop).map(&:intern) # :nodoc:
+  module LowMethods # :nodoc: internal use only
+    private
+    def _do_nothing(*)end
+    ::Bundler::FileUtils::LOW_METHODS.map {|name| alias_method name, :_do_nothing}
+  end
+
+  METHODS = singleton_methods() - [:private_module_function,                  # :nodoc:
+      :commands, :options, :have_option?, :options_of, :collect_method]
+
+  #
+  # This module has all methods of Bundler::FileUtils module, but it outputs messages
+  # before acting.  This equates to passing the <tt>:verbose</tt> flag to
+  # methods in Bundler::FileUtils.
+  #
+  module Verbose
+    include Bundler::FileUtils
+    names = ::Bundler::FileUtils.collect_method(:verbose)
+    names.each do |name|
+      module_eval(<<-EOS, __FILE__, __LINE__ + 1)
+        def #{name}(*args, **options)
+          super(*args, **options, verbose: true)
+        end
+      EOS
+    end
+    private(*names)
+    extend self
+    class << self
+      public(*::Bundler::FileUtils::METHODS)
+    end
+  end
+
+  #
+  # This module has all methods of Bundler::FileUtils module, but never changes
+  # files/directories.  This equates to passing the <tt>:noop</tt> flag
+  # to methods in Bundler::FileUtils.
+  #
+  module NoWrite
+    include Bundler::FileUtils
+    include LowMethods
+    names = ::Bundler::FileUtils.collect_method(:noop)
+    names.each do |name|
+      module_eval(<<-EOS, __FILE__, __LINE__ + 1)
+        def #{name}(*args, **options)
+          super(*args, **options, noop: true)
+        end
+      EOS
+    end
+    private(*names)
+    extend self
+    class << self
+      public(*::Bundler::FileUtils::METHODS)
+    end
+  end
+
+  #
+  # This module has all methods of Bundler::FileUtils module, but never changes
+  # files/directories, with printing message before acting.
+  # This equates to passing the <tt>:noop</tt> and <tt>:verbose</tt> flag
+  # to methods in Bundler::FileUtils.
+  #
+  module DryRun
+    include Bundler::FileUtils
+    include LowMethods
+    names = ::Bundler::FileUtils.collect_method(:noop)
+    names.each do |name|
+      module_eval(<<-EOS, __FILE__, __LINE__ + 1)
+        def #{name}(*args, **options)
+          super(*args, **options, noop: true, verbose: true)
+        end
+      EOS
+    end
+    private(*names)
+    extend self
+    class << self
+      public(*::Bundler::FileUtils::METHODS)
+    end
+  end
+
+end
diff --git a/lib/bundler/vendor/net-http-persistent/lib/net/http/persistent.rb b/lib/bundler/vendor/net-http-persistent/lib/net/http/persistent.rb
new file mode 100644
index 0000000000..93e403a5bb
--- /dev/null
+++ b/lib/bundler/vendor/net-http-persistent/lib/net/http/persistent.rb
@@ -0,0 +1,1153 @@
+require_relative '../../../../../vendored_net_http'
+require_relative '../../../../../vendored_uri'
+begin
+  require 'cgi/escape'
+rescue LoadError
+  require 'cgi/util' # for escaping
+end
+require_relative '../../../../connection_pool/lib/connection_pool'
+
+autoload :OpenSSL, 'openssl'
+
+##
+# Persistent connections for Gem::Net::HTTP
+#
+# Gem::Net::HTTP::Persistent maintains persistent connections across all the
+# servers you wish to talk to.  For each host:port you communicate with a
+# single persistent connection is created.
+#
+# Connections will be shared across threads through a connection pool to
+# increase reuse of connections.
+#
+# You can shut down any remaining HTTP connections when done by calling
+# #shutdown.
+#
+# Example:
+#
+#   require 'bundler/vendor/net-http-persistent/lib/net/http/persistent'
+#
+#   uri = Gem::URI 'http://example.com/awesome/web/service'
+#
+#   http = Gem::Net::HTTP::Persistent.new
+#
+#   # perform a GET
+#   response = http.request uri
+#
+#   # or
+#
+#   get = Gem::Net::HTTP::Get.new uri.request_uri
+#   response = http.request get
+#
+#   # create a POST
+#   post_uri = uri + 'create'
+#   post = Gem::Net::HTTP::Post.new post_uri.path
+#   post.set_form_data 'some' => 'cool data'
+#
+#   # perform the POST, the Gem::URI is always required
+#   response http.request post_uri, post
+#
+# ⚠ Note that for GET, HEAD and other requests that do not have a body,
+# it uses Gem::URI#request_uri as default to send query params
+#
+# == TLS/SSL
+#
+# TLS connections are automatically created depending upon the scheme of the
+# Gem::URI.  TLS connections are automatically verified against the default
+# certificate store for your computer.  You can override this by changing
+# verify_mode or by specifying an alternate cert_store.
+#
+# Here are the TLS settings, see the individual methods for documentation:
+#
+# #certificate        :: This client's certificate
+# #ca_file            :: The certificate-authorities
+# #ca_path            :: Directory with certificate-authorities
+# #cert_store         :: An SSL certificate store
+# #ciphers            :: List of SSl ciphers allowed
+# #extra_chain_cert   :: Extra certificates to be added to the certificate chain
+# #private_key        :: The client's SSL private key
+# #reuse_ssl_sessions :: Reuse a previously opened SSL session for a new
+#                        connection
+# #ssl_timeout        :: Session lifetime
+# #ssl_version        :: Which specific SSL version to use
+# #verify_callback    :: For server certificate verification
+# #verify_depth       :: Depth of certificate verification
+# #verify_mode        :: How connections should be verified
+# #verify_hostname    :: Use hostname verification for server certificate
+#                        during the handshake
+#
+# == Proxies
+#
+# A proxy can be set through #proxy= or at initialization time by providing a
+# second argument to ::new.  The proxy may be the Gem::URI of the proxy server or
+# <code>:ENV</code> which will consult environment variables.
+#
+# See #proxy= and #proxy_from_env for details.
+#
+# == Headers
+#
+# Headers may be specified for use in every request.  #headers are appended to
+# any headers on the request.  #override_headers replace existing headers on
+# the request.
+#
+# The difference between the two can be seen in setting the User-Agent.  Using
+# <code>http.headers['User-Agent'] = 'MyUserAgent'</code> will send "Ruby,
+# MyUserAgent" while <code>http.override_headers['User-Agent'] =
+# 'MyUserAgent'</code> will send "MyUserAgent".
+#
+# == Tuning
+#
+# === Segregation
+#
+# Each Gem::Net::HTTP::Persistent instance has its own pool of connections.  There
+# is no sharing with other instances (as was true in earlier versions).
+#
+# === Idle Timeout
+#
+# If a connection hasn't been used for this number of seconds it will
+# automatically be reset upon the next use to avoid attempting to send to a
+# closed connection.  The default value is 5 seconds. nil means no timeout.
+# Set through #idle_timeout.
+#
+# Reducing this value may help avoid the "too many connection resets" error
+# when sending non-idempotent requests while increasing this value will cause
+# fewer round-trips.
+#
+# === Read Timeout
+#
+# The amount of time allowed between reading two chunks from the socket.  Set
+# through #read_timeout
+#
+# === Max Requests
+#
+# The number of requests that should be made before opening a new connection.
+# Typically many keep-alive capable servers tune this to 100 or less, so the
+# 101st request will fail with ECONNRESET. If unset (default), this value has
+# no effect, if set, connections will be reset on the request after
+# max_requests.
+#
+# === Open Timeout
+#
+# The amount of time to wait for a connection to be opened.  Set through
+# #open_timeout.
+#
+# === Socket Options
+#
+# Socket options may be set on newly-created connections.  See #socket_options
+# for details.
+#
+# === Connection Termination
+#
+# If you are done using the Gem::Net::HTTP::Persistent instance you may shut down
+# all the connections in the current thread with #shutdown.  This is not
+# recommended for normal use, it should only be used when it will be several
+# minutes before you make another HTTP request.
+#
+# If you are using multiple threads, call #shutdown in each thread when the
+# thread is done making requests.  If you don't call shutdown, that's OK.
+# Ruby will automatically garbage collect and shutdown your HTTP connections
+# when the thread terminates.
+
+class Gem::Net::HTTP::Persistent
+
+  ##
+  # The beginning of Time
+
+  EPOCH = Time.at 0 # :nodoc:
+
+  ##
+  # Is OpenSSL available?  This test works with autoload
+
+  HAVE_OPENSSL = defined? OpenSSL::SSL # :nodoc:
+
+  ##
+  # The default connection pool size is 1/4 the allowed open files
+  # (<code>ulimit -n</code>) or 256 if your OS does not support file handle
+  # limits (typically windows).
+
+  if Process.const_defined? :RLIMIT_NOFILE
+    open_file_limits = Process.getrlimit(Process::RLIMIT_NOFILE)
+
+    # Under JRuby on Windows Process responds to `getrlimit` but returns something that does not match docs
+    if open_file_limits.respond_to?(:first)
+      DEFAULT_POOL_SIZE = open_file_limits.first / 4
+    else
+      DEFAULT_POOL_SIZE = 256
+    end
+  else
+    DEFAULT_POOL_SIZE = 256
+  end
+
+  ##
+  # The version of Gem::Net::HTTP::Persistent you are using
+
+  VERSION = '4.0.6'
+
+  ##
+  # Error class for errors raised by Gem::Net::HTTP::Persistent.  Various
+  # SystemCallErrors are re-raised with a human-readable message under this
+  # class.
+
+  class Error < StandardError; end
+
+  ##
+  # Use this method to detect the idle timeout of the host at +uri+.  The
+  # value returned can be used to configure #idle_timeout.  +max+ controls the
+  # maximum idle timeout to detect.
+  #
+  # After
+  #
+  # Idle timeout detection is performed by creating a connection then
+  # performing a HEAD request in a loop until the connection terminates
+  # waiting one additional second per loop.
+  #
+  # NOTE:  This may not work on ruby > 1.9.
+
+  def self.detect_idle_timeout uri, max = 10
+    uri = Gem::URI uri unless Gem::URI::Generic === uri
+    uri += '/'
+
+    req = Gem::Net::HTTP::Head.new uri.request_uri
+
+    http = new 'net-http-persistent detect_idle_timeout'
+
+    http.connection_for uri do |connection|
+      sleep_time = 0
+
+      http = connection.http
+
+      loop do
+        response = http.request req
+
+        $stderr.puts "HEAD #{uri} => #{response.code}" if $DEBUG
+
+        unless Gem::Net::HTTPOK === response then
+          raise Error, "bad response code #{response.code} detecting idle timeout"
+        end
+
+        break if sleep_time >= max
+
+        sleep_time += 1
+
+        $stderr.puts "sleeping #{sleep_time}" if $DEBUG
+        sleep sleep_time
+      end
+    end
+  rescue
+    # ignore StandardErrors, we've probably found the idle timeout.
+  ensure
+    return sleep_time unless $!
+  end
+
+  ##
+  # This client's OpenSSL::X509::Certificate
+
+  attr_reader :certificate
+
+  ##
+  # For Gem::Net::HTTP parity
+
+  alias cert certificate
+
+  ##
+  # An SSL certificate authority.  Setting this will set verify_mode to
+  # VERIFY_PEER.
+
+  attr_reader :ca_file
+
+  ##
+  # A directory of SSL certificates to be used as certificate authorities.
+  # Setting this will set verify_mode to VERIFY_PEER.
+
+  attr_reader :ca_path
+
+  ##
+  # An SSL certificate store.  Setting this will override the default
+  # certificate store.  See verify_mode for more information.
+
+  attr_reader :cert_store
+
+  ##
+  # The ciphers allowed for SSL connections
+
+  attr_reader :ciphers
+
+  ##
+  # Extra certificates to be added to the certificate chain
+
+  attr_reader :extra_chain_cert
+
+  ##
+  # Sends debug_output to this IO via Gem::Net::HTTP#set_debug_output.
+  #
+  # Never use this method in production code, it causes a serious security
+  # hole.
+
+  attr_accessor :debug_output
+
+  ##
+  # Current connection generation
+
+  attr_reader :generation # :nodoc:
+
+  ##
+  # Headers that are added to every request using Gem::Net::HTTP#add_field
+
+  attr_reader :headers
+
+  ##
+  # Maps host:port to an HTTP version.  This allows us to enable version
+  # specific features.
+
+  attr_reader :http_versions
+
+  ##
+  # Maximum time an unused connection can remain idle before being
+  # automatically closed.
+
+  attr_accessor :idle_timeout
+
+  ##
+  # Maximum number of requests on a connection before it is considered expired
+  # and automatically closed.
+
+  attr_accessor :max_requests
+
+  ##
+  # Number of retries to perform if a request fails.
+  #
+  # See also #max_retries=, Gem::Net::HTTP#max_retries=.
+
+  attr_reader :max_retries
+
+  ##
+  # The value sent in the Keep-Alive header.  Defaults to 30.  Not needed for
+  # HTTP/1.1 servers.
+  #
+  # This may not work correctly for HTTP/1.0 servers
+  #
+  # This method may be removed in a future version as RFC 2616 does not
+  # require this header.
+
+  attr_accessor :keep_alive
+
+  ##
+  # The name for this collection of persistent connections.
+
+  attr_reader :name
+
+  ##
+  # Seconds to wait until a connection is opened.  See Gem::Net::HTTP#open_timeout
+
+  attr_accessor :open_timeout
+
+  ##
+  # Headers that are added to every request using Gem::Net::HTTP#[]=
+
+  attr_reader :override_headers
+
+  ##
+  # This client's SSL private key
+
+  attr_reader :private_key
+
+  ##
+  # For Gem::Net::HTTP parity
+
+  alias key private_key
+
+  ##
+  # The URL through which requests will be proxied
+
+  attr_reader :proxy_uri
+
+  ##
+  # List of host suffixes which will not be proxied
+
+  attr_reader :no_proxy
+
+  ##
+  # Test-only accessor for the connection pool
+
+  attr_reader :pool # :nodoc:
+
+  ##
+  # Seconds to wait until reading one block.  See Gem::Net::HTTP#read_timeout
+
+  attr_accessor :read_timeout
+
+  ##
+  # Seconds to wait until writing one block.  See Gem::Net::HTTP#write_timeout
+
+  attr_accessor :write_timeout
+
+  ##
+  # By default SSL sessions are reused to avoid extra SSL handshakes.  Set
+  # this to false if you have problems communicating with an HTTPS server
+  # like:
+  #
+  #   SSL_connect [...] read finished A: unexpected message (OpenSSL::SSL::SSLError)
+
+  attr_accessor :reuse_ssl_sessions
+
+  ##
+  # An array of options for Socket#setsockopt.
+  #
+  # By default the TCP_NODELAY option is set on sockets.
+  #
+  # To set additional options append them to this array:
+  #
+  #   http.socket_options << [Socket::SOL_SOCKET, Socket::SO_KEEPALIVE, 1]
+
+  attr_reader :socket_options
+
+  ##
+  # Current SSL connection generation
+
+  attr_reader :ssl_generation # :nodoc:
+
+  ##
+  # SSL session lifetime
+
+  attr_reader :ssl_timeout
+
+  ##
+  # SSL version to use.
+  #
+  # By default, the version will be negotiated automatically between client
+  # and server.  Ruby 1.9 and newer only. Deprecated since Ruby 2.5.
+
+  attr_reader :ssl_version
+
+  ##
+  # Minimum SSL version to use, e.g. :TLS1_1
+  #
+  # By default, the version will be negotiated automatically between client
+  # and server.  Ruby 2.5 and newer only.
+
+  attr_reader :min_version
+
+  ##
+  # Maximum SSL version to use, e.g. :TLS1_2
+  #
+  # By default, the version will be negotiated automatically between client
+  # and server.  Ruby 2.5 and newer only.
+
+  attr_reader :max_version
+
+  ##
+  # Where this instance's last-use times live in the thread local variables
+
+  attr_reader :timeout_key # :nodoc:
+
+  ##
+  # SSL verification callback.  Used when ca_file or ca_path is set.
+
+  attr_reader :verify_callback
+
+  ##
+  # Sets the depth of SSL certificate verification
+
+  attr_reader :verify_depth
+
+  ##
+  # HTTPS verify mode.  Defaults to OpenSSL::SSL::VERIFY_PEER which verifies
+  # the server certificate.
+  #
+  # If no ca_file, ca_path or cert_store is set the default system certificate
+  # store is used.
+  #
+  # You can use +verify_mode+ to override any default values.
+
+  attr_reader :verify_mode
+
+  ##
+  # HTTPS verify_hostname.
+  #
+  # If a client sets this to true and enables SNI with SSLSocket#hostname=,
+  # the hostname verification on the server certificate is performed
+  # automatically during the handshake using
+  # OpenSSL::SSL.verify_certificate_identity().
+  #
+  # You can set +verify_hostname+ as true to use hostname verification
+  # during the handshake.
+  #
+  # NOTE: This works with Ruby > 3.0.
+
+  attr_reader :verify_hostname
+
+  ##
+  # Creates a new Gem::Net::HTTP::Persistent.
+  #
+  # Set a +name+ for fun.  Your library name should be good enough, but this
+  # otherwise has no purpose.
+  #
+  # +proxy+ may be set to a Gem::URI::HTTP or :ENV to pick up proxy options from
+  # the environment.  See proxy_from_env for details.
+  #
+  # In order to use a Gem::URI for the proxy you may need to do some extra work
+  # beyond Gem::URI parsing if the proxy requires a password:
+  #
+  #   proxy = Gem::URI 'http://proxy.example'
+  #   proxy.user     = 'AzureDiamond'
+  #   proxy.password = 'hunter2'
+  #
+  # Set +pool_size+ to limit the maximum number of connections allowed.
+  # Defaults to 1/4 the number of allowed file handles or 256 if your OS does
+  # not support a limit on allowed file handles.  You can have no more than
+  # this many threads with active HTTP transactions.
+
+  def initialize name: nil, proxy: nil, pool_size: DEFAULT_POOL_SIZE
+    @name = name
+
+    @debug_output     = nil
+    @proxy_uri        = nil
+    @no_proxy         = []
+    @headers          = {}
+    @override_headers = {}
+    @http_versions    = {}
+    @keep_alive       = 30
+    @open_timeout     = nil
+    @read_timeout     = nil
+    @write_timeout    = nil
+    @idle_timeout     = 5
+    @max_requests     = nil
+    @max_retries      = 1
+    @socket_options   = []
+    @ssl_generation   = 0 # incremented when SSL session variables change
+
+    @socket_options << [Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1] if
+      Socket.const_defined? :TCP_NODELAY
+
+    @pool = Gem::Net::HTTP::Persistent::Pool.new size: pool_size do |http_args|
+      Gem::Net::HTTP::Persistent::Connection.new Gem::Net::HTTP, http_args, @ssl_generation
+    end
+
+    @certificate        = nil
+    @ca_file            = nil
+    @ca_path            = nil
+    @ciphers            = nil
+    @private_key        = nil
+    @ssl_timeout        = nil
+    @ssl_version        = nil
+    @min_version        = nil
+    @max_version        = nil
+    @verify_callback    = nil
+    @verify_depth       = nil
+    @verify_mode        = nil
+    @verify_hostname    = nil
+    @cert_store         = nil
+
+    @generation         = 0 # incremented when proxy Gem::URI changes
+
+    if HAVE_OPENSSL then
+      @verify_mode        = OpenSSL::SSL::VERIFY_PEER
+      @reuse_ssl_sessions = OpenSSL::SSL.const_defined? :Session
+    end
+
+    self.proxy = proxy if proxy
+  end
+
+  ##
+  # Sets this client's OpenSSL::X509::Certificate
+
+  def certificate= certificate
+    @certificate = certificate
+
+    reconnect_ssl
+  end
+
+  # For Gem::Net::HTTP parity
+  alias cert= certificate=
+
+  ##
+  # Sets the SSL certificate authority file.
+
+  def ca_file= file
+    @ca_file = file
+
+    reconnect_ssl
+  end
+
+  ##
+  # Sets the SSL certificate authority path.
+
+  def ca_path= path
+    @ca_path = path
+
+    reconnect_ssl
+  end
+
+  ##
+  # Overrides the default SSL certificate store used for verifying
+  # connections.
+
+  def cert_store= store
+    @cert_store = store
+
+    reconnect_ssl
+  end
+
+  ##
+  # The ciphers allowed for SSL connections
+
+  def ciphers= ciphers
+    @ciphers = ciphers
+
+    reconnect_ssl
+  end
+
+  if Gem::Net::HTTP.method_defined?(:extra_chain_cert=)
+    ##
+    # Extra certificates to be added to the certificate chain.
+    # It is only supported starting from Gem::Net::HTTP version 0.1.1
+    def extra_chain_cert= extra_chain_cert
+      @extra_chain_cert = extra_chain_cert
+
+      reconnect_ssl
+    end
+  else
+    def extra_chain_cert= _extra_chain_cert
+      raise "extra_chain_cert= is not supported by this version of Gem::Net::HTTP"
+    end
+  end
+
+  ##
+  # Creates a new connection for +uri+
+
+  def connection_for uri
+    use_ssl = uri.scheme.downcase == 'https'
+
+    net_http_args = [uri.hostname, uri.port]
+
+    # I'm unsure if uri.host or uri.hostname should be checked against
+    # the proxy bypass list.
+    if @proxy_uri and not proxy_bypass? uri.host, uri.port then
+      net_http_args.concat @proxy_args
+    else
+      net_http_args.concat [nil, nil, nil, nil]
+    end
+
+    connection = @pool.checkout net_http_args
+
+    begin
+      http = connection.http
+
+      connection.ressl @ssl_generation if
+        connection.ssl_generation != @ssl_generation
+
+      if not http.started? then
+        ssl   http if use_ssl
+        start http
+      elsif expired? connection then
+        reset connection
+      end
+
+      http.keep_alive_timeout = @idle_timeout  if @idle_timeout
+      http.max_retries        = @max_retries   if http.respond_to?(:max_retries=)
+      http.read_timeout       = @read_timeout  if @read_timeout
+      http.write_timeout      = @write_timeout if
+        @write_timeout && http.respond_to?(:write_timeout=)
+
+      return yield connection
+    rescue Errno::ECONNREFUSED
+      if http.proxy?
+        address = http.proxy_address
+        port    = http.proxy_port
+      else
+        address = http.address
+        port    = http.port
+      end
+
+      raise Error, "connection refused: #{address}:#{port}"
+    rescue Errno::EHOSTDOWN
+      if http.proxy?
+        address = http.proxy_address
+        port    = http.proxy_port
+      else
+        address = http.address
+        port    = http.port
+      end
+
+      raise Error, "host down: #{address}:#{port}"
+    ensure
+      @pool.checkin net_http_args
+    end
+  end
+
+  ##
+  # CGI::escape wrapper
+
+  def escape str
+    CGI.escape str if str
+  end
+
+  ##
+  # CGI::unescape wrapper
+
+  def unescape str
+    CGI.unescape str if str
+  end
+
+
+  ##
+  # Returns true if the connection should be reset due to an idle timeout, or
+  # maximum request count, false otherwise.
+
+  def expired? connection
+    return true  if     @max_requests && connection.requests >= @max_requests
+    return false unless @idle_timeout
+    return true  if     @idle_timeout.zero?
+
+    Time.now - connection.last_use > @idle_timeout
+  end
+
+  ##
+  # Starts the Gem::Net::HTTP +connection+
+
+  def start http
+    http.set_debug_output @debug_output if @debug_output
+    http.open_timeout = @open_timeout if @open_timeout
+
+    http.start
+
+    socket = http.instance_variable_get :@socket
+
+    if socket then # for fakeweb
+      @socket_options.each do |option|
+        socket.io.setsockopt(*option)
+      end
+    end
+  end
+
+  ##
+  # Finishes the Gem::Net::HTTP +connection+
+
+  def finish connection
+    connection.finish
+
+    connection.http.instance_variable_set :@last_communicated, nil
+    connection.http.instance_variable_set :@ssl_session, nil unless
+      @reuse_ssl_sessions
+  end
+
+  ##
+  # Returns the HTTP protocol version for +uri+
+
+  def http_version uri
+    @http_versions["#{uri.hostname}:#{uri.port}"]
+  end
+
+  ##
+  # Adds "http://" to the String +uri+ if it is missing.
+
+  def normalize_uri uri
+    (uri =~ /^https?:/) ? uri : "http://#{uri}"
+  end
+
+  ##
+  # Set the maximum number of retries for a request.
+  #
+  # Defaults to one retry.
+  #
+  # Set this to 0 to disable retries.
+
+  def max_retries= retries
+    retries = retries.to_int
+
+    raise ArgumentError, "max_retries must be positive" if retries < 0
+
+    @max_retries = retries
+
+    reconnect
+  end
+
+  ##
+  # Sets this client's SSL private key
+
+  def private_key= key
+    @private_key = key
+
+    reconnect_ssl
+  end
+
+  # For Gem::Net::HTTP parity
+  alias key= private_key=
+
+  ##
+  # Sets the proxy server.  The +proxy+ may be the Gem::URI of the proxy server,
+  # the symbol +:ENV+ which will read the proxy from the environment or nil to
+  # disable use of a proxy.  See #proxy_from_env for details on setting the
+  # proxy from the environment.
+  #
+  # If the proxy Gem::URI is set after requests have been made, the next request
+  # will shut-down and re-open all connections.
+  #
+  # The +no_proxy+ query parameter can be used to specify hosts which shouldn't
+  # be reached via proxy; if set it should be a comma separated list of
+  # hostname suffixes, optionally with +:port+ appended, for example
+  # <tt>example.com,some.host:8080</tt>.
+
+  def proxy= proxy
+    @proxy_uri = case proxy
+                 when :ENV      then proxy_from_env
+                 when Gem::URI::HTTP then proxy
+                 when nil       then # ignore
+                 else raise ArgumentError, 'proxy must be :ENV or a Gem::URI::HTTP'
+                 end
+
+    @no_proxy.clear
+
+    if @proxy_uri then
+      @proxy_args = [
+        @proxy_uri.hostname,
+        @proxy_uri.port,
+        unescape(@proxy_uri.user),
+        unescape(@proxy_uri.password),
+      ]
+
+      @proxy_connection_id = [nil, *@proxy_args].join ':'
+
+      if @proxy_uri.query then
+        @no_proxy = Gem::URI.decode_www_form(@proxy_uri.query).filter_map { |k, v| v if k == 'no_proxy' }.join(',').downcase.split(',').map { |x| x.strip }.reject { |x| x.empty? }
+      end
+    end
+
+    reconnect
+    reconnect_ssl
+  end
+
+  ##
+  # Creates a Gem::URI for an HTTP proxy server from ENV variables.
+  #
+  # If +HTTP_PROXY+ is set a proxy will be returned.
+  #
+  # If +HTTP_PROXY_USER+ or +HTTP_PROXY_PASS+ are set the Gem::URI is given the
+  # indicated user and password unless HTTP_PROXY contains either of these in
+  # the Gem::URI.
+  #
+  # The +NO_PROXY+ ENV variable can be used to specify hosts which shouldn't
+  # be reached via proxy; if set it should be a comma separated list of
+  # hostname suffixes, optionally with +:port+ appended, for example
+  # <tt>example.com,some.host:8080</tt>. When set to <tt>*</tt> no proxy will
+  # be returned.
+  #
+  # For Windows users, lowercase ENV variables are preferred over uppercase ENV
+  # variables.
+
+  def proxy_from_env
+    env_proxy = ENV['http_proxy'] || ENV['HTTP_PROXY']
+
+    return nil if env_proxy.nil? or env_proxy.empty?
+
+    uri = Gem::URI normalize_uri env_proxy
+
+    env_no_proxy = ENV['no_proxy'] || ENV['NO_PROXY']
+
+    # '*' is special case for always bypass
+    return nil if env_no_proxy == '*'
+
+    if env_no_proxy then
+      uri.query = "no_proxy=#{escape(env_no_proxy)}"
+    end
+
+    unless uri.user or uri.password then
+      uri.user     = escape ENV['http_proxy_user'] || ENV['HTTP_PROXY_USER']
+      uri.password = escape ENV['http_proxy_pass'] || ENV['HTTP_PROXY_PASS']
+    end
+
+    uri
+  end
+
+  ##
+  # Returns true when proxy should by bypassed for host.
+
+  def proxy_bypass? host, port
+    host = host.downcase
+    host_port = [host, port].join ':'
+
+    @no_proxy.each do |name|
+      return true if host[-name.length, name.length] == name or
+         host_port[-name.length, name.length] == name
+    end
+
+    false
+  end
+
+  ##
+  # Forces reconnection of all HTTP connections, including TLS/SSL
+  # connections.
+
+  def reconnect
+    @generation += 1
+  end
+
+  ##
+  # Forces reconnection of only TLS/SSL connections.
+
+  def reconnect_ssl
+    @ssl_generation += 1
+  end
+
+  ##
+  # Finishes then restarts the Gem::Net::HTTP +connection+
+
+  def reset connection
+    http = connection.http
+
+    finish connection
+
+    start http
+  rescue Errno::ECONNREFUSED
+    e = Error.new "connection refused: #{http.address}:#{http.port}"
+    e.set_backtrace $@
+    raise e
+  rescue Errno::EHOSTDOWN
+    e = Error.new "host down: #{http.address}:#{http.port}"
+    e.set_backtrace $@
+    raise e
+  end
+
+  ##
+  # Makes a request on +uri+.  If +req+ is nil a Gem::Net::HTTP::Get is performed
+  # against +uri+.
+  #
+  # If a block is passed #request behaves like Gem::Net::HTTP#request (the body of
+  # the response will not have been read).
+  #
+  # +req+ must be a Gem::Net::HTTPGenericRequest subclass (see Gem::Net::HTTP for a list).
+
+  def request uri, req = nil, &block
+    uri      = Gem::URI uri
+    req      = request_setup req || uri
+    response = nil
+
+    connection_for uri do |connection|
+      http = connection.http
+
+      begin
+        connection.requests += 1
+
+        response = http.request req, &block
+
+        if req.connection_close? or
+          (response.http_version <= '1.0' and
+            not response.connection_keep_alive?) or
+            response.connection_close? then
+          finish connection
+        end
+      rescue Exception # make sure to close the connection when it was interrupted
+        finish connection
+
+        raise
+      ensure
+        connection.last_use = Time.now
+      end
+    end
+
+    @http_versions["#{uri.hostname}:#{uri.port}"] ||= response.http_version
+
+    response
+  end
+
+  ##
+  # Creates a GET request if +req_or_uri+ is a Gem::URI and adds headers to the
+  # request.
+  #
+  # Returns the request.
+
+  def request_setup req_or_uri # :nodoc:
+    req = if req_or_uri.respond_to? 'request_uri' then
+            Gem::Net::HTTP::Get.new req_or_uri.request_uri
+          else
+            req_or_uri
+          end
+
+    @headers.each do |pair|
+      req.add_field(*pair)
+    end
+
+    @override_headers.each do |name, value|
+      req[name] = value
+    end
+
+    unless req['Connection'] then
+      req.add_field 'Connection', 'keep-alive'
+      req.add_field 'Keep-Alive', @keep_alive
+    end
+
+    req
+  end
+
+  ##
+  # Shuts down all connections. Attempting to checkout a connection after
+  # shutdown will raise an error.
+  #
+  # *NOTE*: Calling shutdown for can be dangerous!
+  #
+  # If any thread is still using a connection it may cause an error!  Call
+  # #shutdown when you are completely done making requests!
+
+  def shutdown
+    @pool.shutdown { |http| http.finish }
+  end
+
+  ##
+  # Discard all existing connections. Subsequent checkouts will create
+  # new connections as needed.
+  #
+  # If any thread is still using a connection it may cause an error!  Call
+  # #reload when you are completely done making requests!
+
+  def reload
+    @pool.reload { |http| http.finish }
+  end
+
+  ##
+  # Enables SSL on +connection+
+
+  def ssl connection
+    connection.use_ssl = true
+
+    connection.ciphers     = @ciphers     if @ciphers
+    connection.ssl_timeout = @ssl_timeout if @ssl_timeout
+    connection.ssl_version = @ssl_version if @ssl_version
+    connection.min_version = @min_version if @min_version
+    connection.max_version = @max_version if @max_version
+
+    connection.verify_depth    = @verify_depth
+    connection.verify_mode     = @verify_mode
+    connection.verify_hostname = @verify_hostname if
+      @verify_hostname != nil && connection.respond_to?(:verify_hostname=)
+
+    if OpenSSL::SSL::VERIFY_PEER == OpenSSL::SSL::VERIFY_NONE and
+       not Object.const_defined?(:I_KNOW_THAT_OPENSSL_VERIFY_PEER_EQUALS_VERIFY_NONE_IS_WRONG) then
+      warn <<-WARNING
+                             !!!SECURITY WARNING!!!
+
+The SSL HTTP connection to:
+
+  #{connection.address}:#{connection.port}
+
+                           !!!MAY NOT BE VERIFIED!!!
+
+On your platform your OpenSSL implementation is broken.
+
+There is no difference between the values of VERIFY_NONE and VERIFY_PEER.
+
+This means that attempting to verify the security of SSL connections may not
+work.  This exposes you to man-in-the-middle exploits, snooping on the
+contents of your connection and other dangers to the security of your data.
+
+To disable this warning define the following constant at top-level in your
+application:
+
+  I_KNOW_THAT_OPENSSL_VERIFY_PEER_EQUALS_VERIFY_NONE_IS_WRONG = nil
+
+      WARNING
+    end
+
+    connection.ca_file = @ca_file if @ca_file
+    connection.ca_path = @ca_path if @ca_path
+
+    if @ca_file or @ca_path then
+      connection.verify_mode = OpenSSL::SSL::VERIFY_PEER
+      connection.verify_callback = @verify_callback if @verify_callback
+    end
+
+    if @certificate and @private_key then
+      connection.cert = @certificate
+      connection.key  = @private_key
+    end
+
+    if defined?(@extra_chain_cert) and @extra_chain_cert
+      connection.extra_chain_cert = @extra_chain_cert
+    end
+
+    connection.cert_store = if @cert_store then
+                              @cert_store
+                            else
+                              store = OpenSSL::X509::Store.new
+                              store.set_default_paths
+                              store
+                            end
+  end
+
+  ##
+  # SSL session lifetime
+
+  def ssl_timeout= ssl_timeout
+    @ssl_timeout = ssl_timeout
+
+    reconnect_ssl
+  end
+
+  ##
+  # SSL version to use
+
+  def ssl_version= ssl_version
+    @ssl_version = ssl_version
+
+    reconnect_ssl
+  end
+
+  ##
+  # Minimum SSL version to use
+
+  def min_version= min_version
+    @min_version = min_version
+
+    reconnect_ssl
+  end
+
+  ##
+  # maximum SSL version to use
+
+  def max_version= max_version
+    @max_version = max_version
+
+    reconnect_ssl
+  end
+
+  ##
+  # Sets the depth of SSL certificate verification
+
+  def verify_depth= verify_depth
+    @verify_depth = verify_depth
+
+    reconnect_ssl
+  end
+
+  ##
+  # Sets the HTTPS verify mode.  Defaults to OpenSSL::SSL::VERIFY_PEER.
+  #
+  # Setting this to VERIFY_NONE is a VERY BAD IDEA and should NEVER be used.
+  # Securely transfer the correct certificate and update the default
+  # certificate store or set the ca file instead.
+
+  def verify_mode= verify_mode
+    @verify_mode = verify_mode
+
+    reconnect_ssl
+  end
+
+  ##
+  # Sets the HTTPS verify_hostname.
+
+  def verify_hostname= verify_hostname
+    @verify_hostname = verify_hostname
+
+    reconnect_ssl
+  end
+
+  ##
+  # SSL verification callback.
+
+  def verify_callback= callback
+    @verify_callback = callback
+
+    reconnect_ssl
+  end
+end
+
+require_relative 'persistent/connection'
+require_relative 'persistent/pool'
diff --git a/lib/bundler/vendor/net-http-persistent/lib/net/http/persistent/connection.rb b/lib/bundler/vendor/net-http-persistent/lib/net/http/persistent/connection.rb
new file mode 100644
index 0000000000..8b9ab5cc78
--- /dev/null
+++ b/lib/bundler/vendor/net-http-persistent/lib/net/http/persistent/connection.rb
@@ -0,0 +1,41 @@
+##
+# A Gem::Net::HTTP connection wrapper that holds extra information for managing the
+# connection's lifetime.
+
+class Gem::Net::HTTP::Persistent::Connection # :nodoc:
+
+  attr_accessor :http
+
+  attr_accessor :last_use
+
+  attr_accessor :requests
+
+  attr_accessor :ssl_generation
+
+  def initialize http_class, http_args, ssl_generation
+    @http           = http_class.new(*http_args)
+    @ssl_generation = ssl_generation
+
+    reset
+  end
+
+  def finish
+    @http.finish
+  rescue IOError
+  ensure
+    reset
+  end
+  alias_method :close, :finish
+
+  def reset
+    @last_use = Gem::Net::HTTP::Persistent::EPOCH
+    @requests = 0
+  end
+
+  def ressl ssl_generation
+    @ssl_generation = ssl_generation
+
+    finish
+  end
+
+end
diff --git a/lib/bundler/vendor/net-http-persistent/lib/net/http/persistent/pool.rb b/lib/bundler/vendor/net-http-persistent/lib/net/http/persistent/pool.rb
new file mode 100644
index 0000000000..04a1e754bf
--- /dev/null
+++ b/lib/bundler/vendor/net-http-persistent/lib/net/http/persistent/pool.rb
@@ -0,0 +1,65 @@
+class Gem::Net::HTTP::Persistent::Pool < Bundler::ConnectionPool # :nodoc:
+
+  attr_reader :available # :nodoc:
+  attr_reader :key # :nodoc:
+
+  def initialize(options = {}, &block)
+    super
+
+    @available = Gem::Net::HTTP::Persistent::TimedStackMulti.new(@size, &block)
+    @key = "current-#{@available.object_id}"
+  end
+
+  def checkin net_http_args
+    if net_http_args.is_a?(Hash) && net_http_args.size == 1 && net_http_args[:force]
+      # Bundler::ConnectionPool 2.4+ calls `checkin(force: true)` after fork.
+      # When this happens, we should remove all connections from Thread.current
+      if stacks = Thread.current[@key]
+        stacks.each do |http_args, connections|
+          connections.each do |conn|
+            @available.push conn, connection_args: http_args
+          end
+          connections.clear
+        end
+      end
+    else
+      stack = Thread.current[@key][net_http_args] ||= []
+
+      raise Bundler::ConnectionPool::Error, 'no connections are checked out' if
+        stack.empty?
+
+      conn = stack.pop
+
+      if stack.empty?
+        @available.push conn, connection_args: net_http_args
+
+        Thread.current[@key].delete(net_http_args)
+        Thread.current[@key] = nil if Thread.current[@key].empty?
+      end
+    end
+    nil
+  end
+
+  def checkout net_http_args
+    stacks = Thread.current[@key] ||= {}
+    stack  = stacks[net_http_args] ||= []
+
+    if stack.empty? then
+      conn = @available.pop connection_args: net_http_args
+    else
+      conn = stack.last
+    end
+
+    stack.push conn
+
+    conn
+  end
+
+  def shutdown
+    Thread.current[@key] = nil
+    super
+  end
+end
+
+require_relative 'timed_stack_multi'
+
diff --git a/lib/bundler/vendor/net-http-persistent/lib/net/http/persistent/timed_stack_multi.rb b/lib/bundler/vendor/net-http-persistent/lib/net/http/persistent/timed_stack_multi.rb
new file mode 100644
index 0000000000..034fbe39b8
--- /dev/null
+++ b/lib/bundler/vendor/net-http-persistent/lib/net/http/persistent/timed_stack_multi.rb
@@ -0,0 +1,80 @@
+class Gem::Net::HTTP::Persistent::TimedStackMulti < Bundler::ConnectionPool::TimedStack # :nodoc:
+
+  ##
+  # Returns a new hash that has arrays for keys
+  #
+  # Using a class method to limit the bindings referenced by the hash's
+  # default_proc
+
+  def self.hash_of_arrays # :nodoc:
+    Hash.new { |h,k| h[k] = [] }
+  end
+
+  def initialize(size = 0, &block)
+    super
+
+    @enqueued = 0
+    @ques = self.class.hash_of_arrays
+    @lru = {}
+    @key = :"connection_args-#{object_id}"
+  end
+
+  def empty?
+    (@created - @enqueued) >= @max
+  end
+
+  def length
+    @max - @created + @enqueued
+  end
+
+  private
+
+  def connection_stored? options = {} # :nodoc:
+    !@ques[options[:connection_args]].empty?
+  end
+
+  def fetch_connection options = {} # :nodoc:
+    connection_args = options[:connection_args]
+
+    @enqueued -= 1
+    lru_update connection_args
+    @ques[connection_args].pop
+  end
+
+  def lru_update connection_args # :nodoc:
+    @lru.delete connection_args
+    @lru[connection_args] = true
+  end
+
+  def shutdown_connections # :nodoc:
+    @ques.each_key do |key|
+      super connection_args: key
+    end
+  end
+
+  def store_connection obj, options = {} # :nodoc:
+    @ques[options[:connection_args]].push obj
+    @enqueued += 1
+  end
+
+  def try_create options = {} # :nodoc:
+    connection_args = options[:connection_args]
+
+    if @created >= @max && @enqueued >= 1
+      oldest, = @lru.first
+      @lru.delete oldest
+      connection = @ques[oldest].pop
+      connection.close if connection.respond_to?(:close)
+
+      @created -= 1
+    end
+
+    if @created < @max
+      @created += 1
+      lru_update connection_args
+      return @create_block.call(connection_args)
+    end
+  end
+
+end
+
diff --git a/lib/bundler/vendor/pub_grub/lib/pub_grub.rb b/lib/bundler/vendor/pub_grub/lib/pub_grub.rb
new file mode 100644
index 0000000000..eaaba3fc98
--- /dev/null
+++ b/lib/bundler/vendor/pub_grub/lib/pub_grub.rb
@@ -0,0 +1,31 @@
+require_relative "pub_grub/package"
+require_relative "pub_grub/static_package_source"
+require_relative "pub_grub/term"
+require_relative "pub_grub/version_range"
+require_relative "pub_grub/version_constraint"
+require_relative "pub_grub/version_union"
+require_relative "pub_grub/version_solver"
+require_relative "pub_grub/incompatibility"
+require_relative 'pub_grub/solve_failure'
+require_relative 'pub_grub/failure_writer'
+require_relative 'pub_grub/version'
+
+module Bundler::PubGrub
+  class << self
+    attr_writer :logger
+
+    def logger
+      @logger || default_logger
+    end
+
+    private
+
+    def default_logger
+      require "logger"
+
+      logger = ::Logger.new(STDERR)
+      logger.level = $DEBUG ? ::Logger::DEBUG : ::Logger::WARN
+      @logger = logger
+    end
+  end
+end
diff --git a/lib/bundler/vendor/pub_grub/lib/pub_grub/assignment.rb b/lib/bundler/vendor/pub_grub/lib/pub_grub/assignment.rb
new file mode 100644
index 0000000000..2236a97b5b
--- /dev/null
+++ b/lib/bundler/vendor/pub_grub/lib/pub_grub/assignment.rb
@@ -0,0 +1,20 @@
+module Bundler::PubGrub
+  class Assignment
+    attr_reader :term, :cause, :decision_level, :index
+    def initialize(term, cause, decision_level, index)
+      @term = term
+      @cause = cause
+      @decision_level = decision_level
+      @index = index
+    end
+
+    def self.decision(package, version, decision_level, index)
+      term = Term.new(VersionConstraint.exact(package, version), true)
+      new(term, :decision, decision_level, index)
+    end
+
+    def decision?
+      cause == :decision
+    end
+  end
+end
diff --git a/lib/bundler/vendor/pub_grub/lib/pub_grub/basic_package_source.rb b/lib/bundler/vendor/pub_grub/lib/pub_grub/basic_package_source.rb
new file mode 100644
index 0000000000..491151ec0b
--- /dev/null
+++ b/lib/bundler/vendor/pub_grub/lib/pub_grub/basic_package_source.rb
@@ -0,0 +1,169 @@
+require_relative 'version_constraint'
+require_relative 'incompatibility'
+
+module Bundler::PubGrub
+  # Types:
+  #
+  # Where possible, Bundler::PubGrub will accept user-defined types, so long as they quack.
+  #
+  # ## "Package":
+  #
+  # This class will be used to represent the various packages being solved for.
+  # .to_s will be called when displaying errors and debugging info, it should
+  # probably return the package's name.
+  # It must also have a reasonable definition of #== and #hash
+  #
+  # Example classes: String ("rails")
+  #
+  #
+  # ## "Version":
+  #
+  # This class will be used to represent a single version number.
+  #
+  # Versions don't need to store their associated package, however they will
+  # only be compared against other versions of the same package.
+  #
+  # It must be Comparible (and implement <=> reasonably)
+  #
+  # Example classes: Gem::Version, Integer
+  #
+  #
+  # ## "Dependency"
+  #
+  # This class represents the requirement one package has on another. It is
+  # returned by dependencies_for(package, version) and will be passed to
+  # parse_dependency to convert it to a format Bundler::PubGrub understands.
+  #
+  # It must also have a reasonable definition of #==
+  #
+  # Example classes: String ("~> 1.0"), Gem::Requirement
+  #
+  class BasicPackageSource
+    # Override me!
+    #
+    # This is called per package to find all possible versions of a package.
+    #
+    # It is called at most once per-package
+    #
+    # Returns: Array of versions for a package, in preferred order of selection
+    def all_versions_for(package)
+      raise NotImplementedError
+    end
+
+    # Override me!
+    #
+    # Returns: Hash in the form of { package => requirement, ... }
+    def dependencies_for(package, version)
+      raise NotImplementedError
+    end
+
+    # Override me!
+    #
+    # Convert a (user-defined) dependency into a format Bundler::PubGrub understands.
+    #
+    # Package is passed to this method but for many implementations is not
+    # needed.
+    #
+    # Returns: either a Bundler::PubGrub::VersionRange, Bundler::PubGrub::VersionUnion, or a
+    #   Bundler::PubGrub::VersionConstraint
+    def parse_dependency(package, dependency)
+      raise NotImplementedError
+    end
+
+    # Override me!
+    #
+    # If not overridden, this will call dependencies_for with the root package.
+    #
+    # Returns: Hash in the form of { package => requirement, ... } (see dependencies_for)
+    def root_dependencies
+      dependencies_for(@root_package, @root_version)
+    end
+
+    def initialize
+      @root_package = Package.root
+      @root_version = Package.root_version
+
+      @sorted_versions = Hash.new do |h,k|
+        if k == @root_package
+          h[k] = [@root_version]
+        else
+          h[k] = all_versions_for(k).sort
+        end
+      end
+
+      @cached_dependencies = Hash.new do |packages, package|
+        if package == @root_package
+          packages[package] = {
+            @root_version => root_dependencies
+          }
+        else
+          packages[package] = Hash.new do |versions, version|
+            versions[version] = dependencies_for(package, version)
+          end
+        end
+      end
+    end
+
+    def versions_for(package, range=VersionRange.any)
+      range.select_versions(@sorted_versions[package])
+    end
+
+    def no_versions_incompatibility_for(_package, unsatisfied_term)
+      cause = Incompatibility::NoVersions.new(unsatisfied_term)
+
+      Incompatibility.new([unsatisfied_term], cause: cause)
+    end
+
+    def incompatibilities_for(package, version)
+      package_deps = @cached_dependencies[package]
+      sorted_versions = @sorted_versions[package]
+      package_deps[version].map do |dep_package, dep_constraint_name|
+        low = high = sorted_versions.index(version)
+
+        # find version low such that all >= low share the same dep
+        while low > 0 &&
+            package_deps[sorted_versions[low - 1]][dep_package] == dep_constraint_name
+          low -= 1
+        end
+        low =
+          if low == 0
+            nil
+          else
+            sorted_versions[low]
+          end
+
+        # find version high such that all < high share the same dep
+        while high < sorted_versions.length &&
+            package_deps[sorted_versions[high]][dep_package] == dep_constraint_name
+          high += 1
+        end
+        high =
+          if high == sorted_versions.length
+            nil
+          else
+            sorted_versions[high]
+          end
+
+        range = VersionRange.new(min: low, max: high, include_min: !low.nil?)
+
+        self_constraint = VersionConstraint.new(package, range: range)
+
+        if !@packages.include?(dep_package)
+          # no such package -> this version is invalid
+        end
+
+        dep_constraint = parse_dependency(dep_package, dep_constraint_name)
+        if !dep_constraint
+          # falsey indicates this dependency was invalid
+          cause = Bundler::PubGrub::Incompatibility::InvalidDependency.new(dep_package, dep_constraint_name)
+          return [Incompatibility.new([Term.new(self_constraint, true)], cause: cause)]
+        elsif !dep_constraint.is_a?(VersionConstraint)
+          # Upgrade range/union to VersionConstraint
+          dep_constraint = VersionConstraint.new(dep_package, range: dep_constraint)
+        end
+
+        Incompatibility.new([Term.new(self_constraint, true), Term.new(dep_constraint, false)], cause: :dependency)
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/pub_grub/lib/pub_grub/failure_writer.rb b/lib/bundler/vendor/pub_grub/lib/pub_grub/failure_writer.rb
new file mode 100644
index 0000000000..ee099b23f4
--- /dev/null
+++ b/lib/bundler/vendor/pub_grub/lib/pub_grub/failure_writer.rb
@@ -0,0 +1,182 @@
+module Bundler::PubGrub
+  class FailureWriter
+    def initialize(root)
+      @root = root
+
+      # { Incompatibility => Integer }
+      @derivations = {}
+
+      # [ [ String, Integer or nil ] ]
+      @lines = []
+
+      # { Incompatibility => Integer }
+      @line_numbers = {}
+
+      count_derivations(root)
+    end
+
+    def write
+      return @root.to_s unless @root.conflict?
+
+      visit(@root)
+
+      padding = @line_numbers.empty? ? 0 : "(#{@line_numbers.values.last}) ".length
+
+      @lines.map do |message, number|
+        next "" if message.empty?
+
+        lead = number ? "(#{number}) " : ""
+        lead = lead.ljust(padding)
+        message = message.gsub("\n", "\n" + " " * (padding + 2))
+        "#{lead}#{message}"
+      end.join("\n")
+    end
+
+    private
+
+    def write_line(incompatibility, message, numbered:)
+      if numbered
+        number = @line_numbers.length + 1
+        @line_numbers[incompatibility] = number
+      end
+
+      @lines << [message, number]
+    end
+
+    def visit(incompatibility, conclusion: false)
+      raise unless incompatibility.conflict?
+
+      numbered = conclusion || @derivations[incompatibility] > 1;
+      conjunction = conclusion || incompatibility == @root ? "So," : "And"
+
+      cause = incompatibility.cause
+
+      if cause.conflict.conflict? && cause.other.conflict?
+        conflict_line = @line_numbers[cause.conflict]
+        other_line = @line_numbers[cause.other]
+
+        if conflict_line && other_line
+          write_line(
+            incompatibility,
+            "Because #{cause.conflict} (#{conflict_line})\nand #{cause.other} (#{other_line}),\n#{incompatibility}.",
+            numbered: numbered
+          )
+        elsif conflict_line || other_line
+          with_line    = conflict_line ? cause.conflict : cause.other
+          without_line = conflict_line ? cause.other : cause.conflict
+          line = @line_numbers[with_line]
+
+          visit(without_line);
+          write_line(
+            incompatibility,
+            "#{conjunction} because #{with_line} (#{line}),\n#{incompatibility}.",
+            numbered: numbered
+          )
+        else
+          single_line_conflict = single_line?(cause.conflict.cause)
+          single_line_other    = single_line?(cause.other.cause)
+
+          if single_line_conflict || single_line_other
+            first  = single_line_other ? cause.conflict : cause.other
+            second = single_line_other ? cause.other : cause.conflict
+            visit(first)
+            visit(second)
+            write_line(
+              incompatibility,
+              "Thus, #{incompatibility}.",
+              numbered: numbered
+            )
+          else
+            visit(cause.conflict, conclusion: true)
+            @lines << ["", nil]
+            visit(cause.other)
+
+            write_line(
+              incompatibility,
+              "#{conjunction} because #{cause.conflict} (#{@line_numbers[cause.conflict]}),\n#{incompatibility}.",
+              numbered: numbered
+            )
+          end
+        end
+      elsif cause.conflict.conflict? || cause.other.conflict?
+        derived = cause.conflict.conflict? ? cause.conflict : cause.other
+        ext     = cause.conflict.conflict? ? cause.other : cause.conflict
+
+        derived_line = @line_numbers[derived]
+        if derived_line
+          write_line(
+            incompatibility,
+            "Because #{ext}\nand #{derived} (#{derived_line}),\n#{incompatibility}.",
+            numbered: numbered
+          )
+        elsif collapsible?(derived)
+          derived_cause = derived.cause
+          if derived_cause.conflict.conflict?
+            collapsed_derived = derived_cause.conflict
+            collapsed_ext = derived_cause.other
+          else
+            collapsed_derived = derived_cause.other
+            collapsed_ext = derived_cause.conflict
+          end
+
+          visit(collapsed_derived)
+
+          write_line(
+            incompatibility,
+            "#{conjunction} because #{collapsed_ext}\nand #{ext},\n#{incompatibility}.",
+            numbered: numbered
+          )
+        else
+          visit(derived)
+          write_line(
+            incompatibility,
+            "#{conjunction} because #{ext},\n#{incompatibility}.",
+            numbered: numbered
+          )
+        end
+      else
+        write_line(
+          incompatibility,
+          "Because #{cause.conflict}\nand #{cause.other},\n#{incompatibility}.",
+          numbered: numbered
+        )
+      end
+    end
+
+    def single_line?(cause)
+      !cause.conflict.conflict? && !cause.other.conflict?
+    end
+
+    def collapsible?(incompatibility)
+      return false if @derivations[incompatibility] > 1
+
+      cause = incompatibility.cause
+      # If incompatibility is derived from two derived incompatibilities,
+      # there are too many transitive causes to display concisely.
+      return false if cause.conflict.conflict? && cause.other.conflict?
+
+      # If incompatibility is derived from two external incompatibilities, it
+      # tends to be confusing to collapse it.
+      return false unless cause.conflict.conflict? || cause.other.conflict?
+
+      # If incompatibility's internal cause is numbered, collapsing it would
+      # get too noisy.
+      complex = cause.conflict.conflict? ? cause.conflict : cause.other
+
+      !@line_numbers.has_key?(complex)
+    end
+
+    def count_derivations(incompatibility)
+      if @derivations.has_key?(incompatibility)
+        @derivations[incompatibility] += 1
+      else
+        @derivations[incompatibility] = 1
+        if incompatibility.conflict?
+          cause = incompatibility.cause
+          count_derivations(cause.conflict)
+          count_derivations(cause.other)
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/pub_grub/lib/pub_grub/incompatibility.rb b/lib/bundler/vendor/pub_grub/lib/pub_grub/incompatibility.rb
new file mode 100644
index 0000000000..239eaf3401
--- /dev/null
+++ b/lib/bundler/vendor/pub_grub/lib/pub_grub/incompatibility.rb
@@ -0,0 +1,150 @@
+module Bundler::PubGrub
+  class Incompatibility
+    ConflictCause = Struct.new(:incompatibility, :satisfier) do
+      alias_method :conflict, :incompatibility
+      alias_method :other, :satisfier
+    end
+
+    InvalidDependency = Struct.new(:package, :constraint) do
+    end
+
+    NoVersions = Struct.new(:constraint) do
+    end
+
+    attr_reader :terms, :cause
+
+    def initialize(terms, cause:, custom_explanation: nil)
+      @cause = cause
+      @terms = cleanup_terms(terms)
+      @custom_explanation = custom_explanation
+
+      if cause == :dependency && @terms.length != 2
+        raise ArgumentError, "a dependency Incompatibility must have exactly two terms. Got #{@terms.inspect}"
+      end
+    end
+
+    def hash
+      cause.hash ^ terms.hash
+    end
+
+    def eql?(other)
+      cause.eql?(other.cause) &&
+        terms.eql?(other.terms)
+    end
+
+    def failure?
+      terms.empty? || (terms.length == 1 && Package.root?(terms[0].package) && terms[0].positive?)
+    end
+
+    def conflict?
+      ConflictCause === cause
+    end
+
+    # Returns all external incompatibilities in this incompatibility's
+    # derivation graph
+    def external_incompatibilities
+      if conflict?
+        [
+          cause.conflict,
+          cause.other
+        ].flat_map(&:external_incompatibilities)
+      else
+        [this]
+      end
+    end
+
+    def to_s
+      return @custom_explanation if @custom_explanation
+
+      case cause
+      when :root
+        "(root dependency)"
+      when :dependency
+        "#{terms[0].to_s(allow_every: true)} depends on #{terms[1].invert}"
+      when Bundler::PubGrub::Incompatibility::InvalidDependency
+        "#{terms[0].to_s(allow_every: true)} depends on unknown package #{cause.package}"
+      when Bundler::PubGrub::Incompatibility::NoVersions
+        "no versions satisfy #{cause.constraint}"
+      when Bundler::PubGrub::Incompatibility::ConflictCause
+        if failure?
+          "version solving has failed"
+        elsif terms.length == 1
+          term = terms[0]
+          if term.positive?
+            if term.constraint.any?
+              "#{term.package} cannot be used"
+            else
+              "#{term.to_s(allow_every: true)} cannot be used"
+            end
+          else
+            "#{term.invert} is required"
+          end
+        else
+          if terms.all?(&:positive?)
+            if terms.length == 2
+              "#{terms[0].to_s(allow_every: true)} is incompatible with #{terms[1]}"
+            else
+              "one of #{terms.map(&:to_s).join(" or ")} must be false"
+            end
+          elsif terms.all?(&:negative?)
+            if terms.length == 2
+              "either #{terms[0].invert} or #{terms[1].invert}"
+            else
+              "one of #{terms.map(&:invert).join(" or ")} must be true";
+            end
+          else
+            positive = terms.select(&:positive?)
+            negative = terms.select(&:negative?).map(&:invert)
+
+            if positive.length == 1
+              "#{positive[0].to_s(allow_every: true)} requires #{negative.join(" or ")}"
+            else
+              "if #{positive.join(" and ")} then #{negative.join(" or ")}"
+            end
+          end
+        end
+      else
+        raise "unhandled cause: #{cause.inspect}"
+      end
+    end
+
+    def inspect
+      "#<#{self.class} #{to_s}>"
+    end
+
+    def pretty_print(q)
+      q.group 2, "#<#{self.class}", ">" do
+        q.breakable
+        q.text to_s
+
+        q.breakable
+        q.text " caused by "
+        q.pp @cause
+      end
+    end
+
+    private
+
+    def cleanup_terms(terms)
+      terms.each do |term|
+        raise "#{term.inspect} must be a term" unless term.is_a?(Term)
+      end
+
+      if terms.length != 1 && ConflictCause === cause
+        terms = terms.reject do |term|
+          term.positive? && Package.root?(term.package)
+        end
+      end
+
+      # Optimized simple cases
+      return terms if terms.length <= 1
+      return terms if terms.length == 2 && terms[0].package != terms[1].package
+
+      terms.group_by(&:package).map do |package, common_terms|
+        common_terms.inject do |acc, term|
+          acc.intersect(term)
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/pub_grub/lib/pub_grub/package.rb b/lib/bundler/vendor/pub_grub/lib/pub_grub/package.rb
new file mode 100644
index 0000000000..efb9d3da16
--- /dev/null
+++ b/lib/bundler/vendor/pub_grub/lib/pub_grub/package.rb
@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+module Bundler::PubGrub
+  class Package
+
+    attr_reader :name
+
+    def initialize(name)
+      @name = name
+    end
+
+    def inspect
+      "#<#{self.class} #{name.inspect}>"
+    end
+
+    def <=>(other)
+      name <=> other.name
+    end
+
+    ROOT = Package.new(:root)
+    ROOT_VERSION = 0
+
+    def self.root
+      ROOT
+    end
+
+    def self.root_version
+      ROOT_VERSION
+    end
+
+    def self.root?(package)
+      if package.respond_to?(:root?)
+        package.root?
+      else
+        package == root
+      end
+    end
+
+    def to_s
+      name.to_s
+    end
+  end
+end
diff --git a/lib/bundler/vendor/pub_grub/lib/pub_grub/partial_solution.rb b/lib/bundler/vendor/pub_grub/lib/pub_grub/partial_solution.rb
new file mode 100644
index 0000000000..4c4b8ca844
--- /dev/null
+++ b/lib/bundler/vendor/pub_grub/lib/pub_grub/partial_solution.rb
@@ -0,0 +1,121 @@
+require_relative 'assignment'
+
+module Bundler::PubGrub
+  class PartialSolution
+    attr_reader :assignments, :decisions
+    attr_reader :attempted_solutions
+
+    def initialize
+      reset!
+
+      @attempted_solutions = 1
+      @backtracking = false
+    end
+
+    def decision_level
+      @decisions.length
+    end
+
+    def relation(term)
+      package = term.package
+      return :overlap if !@terms.key?(package)
+
+      @relation_cache[package][term] ||=
+        @terms[package].relation(term)
+    end
+
+    def satisfies?(term)
+      relation(term) == :subset
+    end
+
+    def derive(term, cause)
+      add_assignment(Assignment.new(term, cause, decision_level, assignments.length))
+    end
+
+    def satisfier(term)
+      assignment =
+        @assignments_by[term.package].bsearch do |assignment_by|
+          @cumulative_assignments[assignment_by].satisfies?(term)
+        end
+
+      assignment || raise("#{term} unsatisfied")
+    end
+
+    # A list of unsatisfied terms
+    def unsatisfied
+      @required.keys.reject do |package|
+        @decisions.key?(package)
+      end.map do |package|
+        @terms[package]
+      end
+    end
+
+    def decide(package, version)
+      @attempted_solutions += 1 if @backtracking
+      @backtracking = false;
+
+      decisions[package] = version
+      assignment = Assignment.decision(package, version, decision_level, assignments.length)
+      add_assignment(assignment)
+    end
+
+    def backtrack(previous_level)
+      @backtracking = true
+
+      new_assignments = assignments.select do |assignment|
+        assignment.decision_level <= previous_level
+      end
+
+      new_decisions = Hash[decisions.first(previous_level)]
+
+      reset!
+
+      @decisions = new_decisions
+
+      new_assignments.each do |assignment|
+        add_assignment(assignment)
+      end
+    end
+
+    private
+
+    def reset!
+      # { Array<Assignment> }
+      @assignments = []
+
+      # { Package => Array<Assignment> }
+      @assignments_by = Hash.new { |h,k| h[k] = [] }
+      @cumulative_assignments = {}.compare_by_identity
+
+      # { Package => Package::Version }
+      @decisions = {}
+
+      # { Package => Term }
+      @terms = {}
+      @relation_cache = Hash.new { |h,k| h[k] = {} }
+
+      # { Package => Boolean }
+      @required = {}
+    end
+
+    def add_assignment(assignment)
+      term = assignment.term
+      package = term.package
+
+      @assignments << assignment
+      @assignments_by[package] << assignment
+
+      @required[package] = true if term.positive?
+
+      if @terms.key?(package)
+        old_term = @terms[package]
+        @terms[package] = old_term.intersect(term)
+      else
+        @terms[package] = term
+      end
+      @relation_cache[package].clear
+
+      @cumulative_assignments[assignment] = @terms[package]
+    end
+  end
+end
diff --git a/lib/bundler/vendor/pub_grub/lib/pub_grub/rubygems.rb b/lib/bundler/vendor/pub_grub/lib/pub_grub/rubygems.rb
new file mode 100644
index 0000000000..245c23be22
--- /dev/null
+++ b/lib/bundler/vendor/pub_grub/lib/pub_grub/rubygems.rb
@@ -0,0 +1,45 @@
+module Bundler::PubGrub
+  module RubyGems
+    extend self
+
+    def requirement_to_range(requirement)
+      ranges = requirement.requirements.map do |(op, ver)|
+        case op
+        when "~>"
+          name = "~> #{ver}"
+          bump = ver.class.new(ver.bump.to_s + ".A")
+          VersionRange.new(name: name, min: ver, max: bump, include_min: true)
+        when ">"
+          VersionRange.new(min: ver)
+        when ">="
+          VersionRange.new(min: ver, include_min: true)
+        when "<"
+          VersionRange.new(max: ver)
+        when "<="
+          VersionRange.new(max: ver, include_max: true)
+        when "="
+          VersionRange.new(min: ver, max: ver, include_min: true, include_max: true)
+        when "!="
+          VersionRange.new(min: ver, max: ver, include_min: true, include_max: true).invert
+        else
+          raise "bad version specifier: #{op}"
+        end
+      end
+
+      ranges.inject(&:intersect)
+    end
+
+    def requirement_to_constraint(package, requirement)
+      Bundler::PubGrub::VersionConstraint.new(package, range: requirement_to_range(requirement))
+    end
+
+    def parse_range(dep)
+      requirement_to_range(Gem::Requirement.new(dep))
+    end
+
+    def parse_constraint(package, dep)
+      range = parse_range(dep)
+      Bundler::PubGrub::VersionConstraint.new(package, range: range)
+    end
+  end
+end
diff --git a/lib/bundler/vendor/pub_grub/lib/pub_grub/solve_failure.rb b/lib/bundler/vendor/pub_grub/lib/pub_grub/solve_failure.rb
new file mode 100644
index 0000000000..961a7a7c0c
--- /dev/null
+++ b/lib/bundler/vendor/pub_grub/lib/pub_grub/solve_failure.rb
@@ -0,0 +1,19 @@
+require_relative 'failure_writer'
+
+module Bundler::PubGrub
+  class SolveFailure < StandardError
+    attr_reader :incompatibility
+
+    def initialize(incompatibility)
+      @incompatibility = incompatibility
+    end
+
+    def to_s
+      "Could not find compatible versions\n\n#{explanation}"
+    end
+
+    def explanation
+      @explanation ||= FailureWriter.new(@incompatibility).write
+    end
+  end
+end
diff --git a/lib/bundler/vendor/pub_grub/lib/pub_grub/static_package_source.rb b/lib/bundler/vendor/pub_grub/lib/pub_grub/static_package_source.rb
new file mode 100644
index 0000000000..36ab06254d
--- /dev/null
+++ b/lib/bundler/vendor/pub_grub/lib/pub_grub/static_package_source.rb
@@ -0,0 +1,61 @@
+require_relative 'package'
+require_relative 'rubygems'
+require_relative 'version_constraint'
+require_relative 'incompatibility'
+require_relative 'basic_package_source'
+
+module Bundler::PubGrub
+  class StaticPackageSource < BasicPackageSource
+    class DSL
+      def initialize(packages, root_deps)
+        @packages = packages
+        @root_deps = root_deps
+      end
+
+      def root(deps:)
+        @root_deps.update(deps)
+      end
+
+      def add(name, version, deps: {})
+        version = Gem::Version.new(version)
+        @packages[name] ||= {}
+        raise ArgumentError, "#{name} #{version} declared twice" if @packages[name].key?(version)
+        @packages[name][version] = clean_deps(name, version, deps)
+      end
+
+      private
+
+      # Exclude redundant self-referencing dependencies
+      def clean_deps(name, version, deps)
+        deps.reject {|dep_name, req| name == dep_name && Bundler::PubGrub::RubyGems.parse_range(req).include?(version) }
+      end
+    end
+
+    def initialize
+      @root_deps = {}
+      @packages = {}
+
+      yield DSL.new(@packages, @root_deps)
+
+      super()
+    end
+
+    def all_versions_for(package)
+      @packages[package].keys
+    end
+
+    def root_dependencies
+      @root_deps
+    end
+
+    def dependencies_for(package, version)
+      @packages[package][version]
+    end
+
+    def parse_dependency(package, dependency)
+      return false unless @packages.key?(package)
+
+      Bundler::PubGrub::RubyGems.parse_constraint(package, dependency)
+    end
+  end
+end
diff --git a/lib/bundler/vendor/pub_grub/lib/pub_grub/strategy.rb b/lib/bundler/vendor/pub_grub/lib/pub_grub/strategy.rb
new file mode 100644
index 0000000000..6955655ba4
--- /dev/null
+++ b/lib/bundler/vendor/pub_grub/lib/pub_grub/strategy.rb
@@ -0,0 +1,42 @@
+module Bundler::PubGrub
+  class Strategy
+    def initialize(source)
+      @source = source
+
+      @root_package = Package.root
+      @root_version = Package.root_version
+
+      @version_indexes = Hash.new do |h,k|
+        if k == @root_package
+          h[k] = { @root_version => 0 }
+        else
+          h[k] = @source.all_versions_for(k).each.with_index.to_h
+        end
+      end
+    end
+
+    def next_package_and_version(unsatisfied)
+      package, range = next_term_to_try_from(unsatisfied)
+
+      [package, most_preferred_version_of(package, range)]
+    end
+
+    private
+
+    def most_preferred_version_of(package, range)
+      versions = @source.versions_for(package, range)
+
+      indexes = @version_indexes[package]
+      versions.min_by { |version| indexes[version] }
+    end
+
+    def next_term_to_try_from(unsatisfied)
+      unsatisfied.min_by do |package, range|
+        matching_versions = @source.versions_for(package, range)
+        higher_versions = @source.versions_for(package, range.upper_invert)
+
+        [matching_versions.count <= 1 ? 0 : 1, higher_versions.count]
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/pub_grub/lib/pub_grub/term.rb b/lib/bundler/vendor/pub_grub/lib/pub_grub/term.rb
new file mode 100644
index 0000000000..1d0f763378
--- /dev/null
+++ b/lib/bundler/vendor/pub_grub/lib/pub_grub/term.rb
@@ -0,0 +1,105 @@
+module Bundler::PubGrub
+  class Term
+    attr_reader :package, :constraint, :positive
+
+    def initialize(constraint, positive)
+      @constraint = constraint
+      @package = @constraint.package
+      @positive = positive
+    end
+
+    def to_s(allow_every: false)
+      if positive
+        @constraint.to_s(allow_every: allow_every)
+      else
+        "not #{@constraint}"
+      end
+    end
+
+    def hash
+      constraint.hash ^ positive.hash
+    end
+
+    def eql?(other)
+      positive == other.positive &&
+        constraint.eql?(other.constraint)
+    end
+
+    def invert
+      self.class.new(@constraint, !@positive)
+    end
+    alias_method :inverse, :invert
+
+    def intersect(other)
+      raise ArgumentError, "packages must match" if package != other.package
+
+      if positive? && other.positive?
+        self.class.new(constraint.intersect(other.constraint), true)
+      elsif negative? && other.negative?
+        self.class.new(constraint.union(other.constraint), false)
+      else
+        positive = positive? ? self : other
+        negative = negative? ? self : other
+        self.class.new(positive.constraint.intersect(negative.constraint.invert), true)
+      end
+    end
+
+    def difference(other)
+      intersect(other.invert)
+    end
+
+    def relation(other)
+      if positive? && other.positive?
+        constraint.relation(other.constraint)
+      elsif negative? && other.positive?
+        if constraint.allows_all?(other.constraint)
+          :disjoint
+        else
+          :overlap
+        end
+      elsif positive? && other.negative?
+        if !other.constraint.allows_any?(constraint)
+          :subset
+        elsif other.constraint.allows_all?(constraint)
+          :disjoint
+        else
+          :overlap
+        end
+      elsif negative? && other.negative?
+        if constraint.allows_all?(other.constraint)
+          :subset
+        else
+          :overlap
+        end
+      else
+        raise
+      end
+    end
+
+    def normalized_constraint
+      @normalized_constraint ||= positive ? constraint : constraint.invert
+    end
+
+    def satisfies?(other)
+      raise ArgumentError, "packages must match" unless package == other.package
+
+      relation(other) == :subset
+    end
+
+    def positive?
+      @positive
+    end
+
+    def negative?
+      !positive?
+    end
+
+    def empty?
+      @empty ||= normalized_constraint.empty?
+    end
+
+    def inspect
+      "#<#{self.class} #{self}>"
+    end
+  end
+end
diff --git a/lib/bundler/vendor/pub_grub/lib/pub_grub/version.rb b/lib/bundler/vendor/pub_grub/lib/pub_grub/version.rb
new file mode 100644
index 0000000000..d7984b3863
--- /dev/null
+++ b/lib/bundler/vendor/pub_grub/lib/pub_grub/version.rb
@@ -0,0 +1,3 @@
+module Bundler::PubGrub
+  VERSION = "0.5.0"
+end
diff --git a/lib/bundler/vendor/pub_grub/lib/pub_grub/version_constraint.rb b/lib/bundler/vendor/pub_grub/lib/pub_grub/version_constraint.rb
new file mode 100644
index 0000000000..b71f3eaf53
--- /dev/null
+++ b/lib/bundler/vendor/pub_grub/lib/pub_grub/version_constraint.rb
@@ -0,0 +1,129 @@
+require_relative 'version_range'
+
+module Bundler::PubGrub
+  class VersionConstraint
+    attr_reader :package, :range
+
+    # @param package [Bundler::PubGrub::Package]
+    # @param range [Bundler::PubGrub::VersionRange]
+    def initialize(package, range: nil)
+      @package = package
+      @range = range
+    end
+
+    def hash
+      package.hash ^ range.hash
+    end
+
+    def ==(other)
+      package == other.package &&
+        range == other.range
+    end
+
+    def eql?(other)
+      package.eql?(other.package) &&
+        range.eql?(other.range)
+    end
+
+    class << self
+      def exact(package, version)
+        range = VersionRange.new(min: version, max: version, include_min: true, include_max: true)
+        new(package, range: range)
+      end
+
+      def any(package)
+        new(package, range: VersionRange.any)
+      end
+
+      def empty(package)
+        new(package, range: VersionRange.empty)
+      end
+    end
+
+    def intersect(other)
+      unless package == other.package
+        raise ArgumentError, "Can only intersect between VersionConstraint of the same package"
+      end
+
+      self.class.new(package, range: range.intersect(other.range))
+    end
+
+    def union(other)
+      unless package == other.package
+        raise ArgumentError, "Can only intersect between VersionConstraint of the same package"
+      end
+
+      self.class.new(package, range: range.union(other.range))
+    end
+
+    def invert
+      new_range = range.invert
+      self.class.new(package, range: new_range)
+    end
+
+    def difference(other)
+      intersect(other.invert)
+    end
+
+    def allows_all?(other)
+      range.allows_all?(other.range)
+    end
+
+    def allows_any?(other)
+      range.intersects?(other.range)
+    end
+
+    def subset?(other)
+      other.allows_all?(self)
+    end
+
+    def overlap?(other)
+      other.allows_any?(self)
+    end
+
+    def disjoint?(other)
+      !overlap?(other)
+    end
+
+    def relation(other)
+      if subset?(other)
+        :subset
+      elsif overlap?(other)
+        :overlap
+      else
+        :disjoint
+      end
+    end
+
+    def to_s(allow_every: false)
+      if Package.root?(package)
+        package.to_s
+      elsif allow_every && any?
+        "every version of #{package}"
+      else
+        "#{package} #{constraint_string}"
+      end
+    end
+
+    def constraint_string
+      if any?
+        ">= 0"
+      else
+        range.to_s
+      end
+    end
+
+    def empty?
+      range.empty?
+    end
+
+    # Does this match every version of the package
+    def any?
+      range.any?
+    end
+
+    def inspect
+      "#<#{self.class} #{self}>"
+    end
+  end
+end
diff --git a/lib/bundler/vendor/pub_grub/lib/pub_grub/version_range.rb b/lib/bundler/vendor/pub_grub/lib/pub_grub/version_range.rb
new file mode 100644
index 0000000000..49dcf716a3
--- /dev/null
+++ b/lib/bundler/vendor/pub_grub/lib/pub_grub/version_range.rb
@@ -0,0 +1,423 @@
+# frozen_string_literal: true
+
+module Bundler::PubGrub
+  class VersionRange
+    attr_reader :min, :max, :include_min, :include_max
+
+    alias_method :include_min?, :include_min
+    alias_method :include_max?, :include_max
+
+    class Empty < VersionRange
+      undef_method :min, :max
+      undef_method :include_min, :include_min?
+      undef_method :include_max, :include_max?
+
+      def initialize
+      end
+
+      def empty?
+        true
+      end
+
+      def eql?(other)
+        other.empty?
+      end
+
+      def hash
+        [].hash
+      end
+
+      def intersects?(_)
+        false
+      end
+
+      def intersect(other)
+        self
+      end
+
+      def allows_all?(other)
+        other.empty?
+      end
+
+      def include?(_)
+        false
+      end
+
+      def any?
+        false
+      end
+
+      def to_s
+        "(no versions)"
+      end
+
+      def ==(other)
+        other.class == self.class
+      end
+
+      def invert
+        VersionRange.any
+      end
+
+      def select_versions(_)
+        []
+      end
+    end
+
+    EMPTY = Empty.new
+    Empty.singleton_class.undef_method(:new)
+
+    def self.empty
+      EMPTY
+    end
+
+    def self.any
+      new
+    end
+
+    def initialize(min: nil, max: nil, include_min: false, include_max: false, name: nil)
+      raise ArgumentError, "Ranges without a lower bound cannot have include_min == true" if !min && include_min == true
+      raise ArgumentError, "Ranges without an upper bound cannot have include_max == true" if !max && include_max == true
+
+      @min = min
+      @max = max
+      @include_min = include_min
+      @include_max = include_max
+      @name = name
+    end
+
+    def hash
+      @hash ||= min.hash ^ max.hash ^ include_min.hash ^ include_max.hash
+    end
+
+    def eql?(other)
+      if other.is_a?(VersionRange)
+        !other.empty? &&
+          min.eql?(other.min) &&
+          max.eql?(other.max) &&
+          include_min.eql?(other.include_min) &&
+          include_max.eql?(other.include_max)
+      else
+        ranges.eql?(other.ranges)
+      end
+    end
+
+    def ranges
+      [self]
+    end
+
+    def include?(version)
+      compare_version(version) == 0
+    end
+
+    # Partitions passed versions into [lower, within, higher]
+    #
+    # versions must be sorted
+    def partition_versions(versions)
+      min_index =
+        if !min || versions.empty?
+          0
+        elsif include_min?
+          (0..versions.size).bsearch { |i| versions[i].nil? || versions[i] >= min }
+        else
+          (0..versions.size).bsearch { |i| versions[i].nil? || versions[i] > min }
+        end
+
+      lower = versions.slice(0, min_index)
+      versions = versions.slice(min_index, versions.size)
+
+      max_index =
+        if !max || versions.empty?
+          versions.size
+        elsif include_max?
+          (0..versions.size).bsearch { |i| versions[i].nil? || versions[i] > max }
+        else
+          (0..versions.size).bsearch { |i| versions[i].nil? || versions[i] >= max }
+        end
+
+      [
+        lower,
+        versions.slice(0, max_index),
+        versions.slice(max_index, versions.size)
+      ]
+    end
+
+    # Returns versions which are included by this range.
+    #
+    # versions must be sorted
+    def select_versions(versions)
+      return versions if any?
+
+      partition_versions(versions)[1]
+    end
+
+    def compare_version(version)
+      if min
+        case version <=> min
+        when -1
+          return -1
+        when 0
+          return -1 if !include_min
+        when 1
+        end
+      end
+
+      if max
+        case version <=> max
+        when -1
+        when 0
+          return 1 if !include_max
+        when 1
+          return 1
+        end
+      end
+
+      0
+    end
+
+    def strictly_lower?(other)
+      return false if !max || !other.min
+
+      case max <=> other.min
+      when 0
+        !include_max || !other.include_min
+      when -1
+        true
+      when 1
+        false
+      end
+    end
+
+    def strictly_higher?(other)
+      other.strictly_lower?(self)
+    end
+
+    def intersects?(other)
+      return false if other.empty?
+      return other.intersects?(self) if other.is_a?(VersionUnion)
+      !strictly_lower?(other) && !strictly_higher?(other)
+    end
+    alias_method :allows_any?, :intersects?
+
+    def intersect(other)
+      return other if other.empty?
+      return other.intersect(self) if other.is_a?(VersionUnion)
+
+      min_range =
+        if !min
+          other
+        elsif !other.min
+          self
+        else
+          case min <=> other.min
+          when 0
+            include_min ? other : self
+          when -1
+            other
+          when 1
+            self
+          end
+        end
+
+      max_range =
+        if !max
+          other
+        elsif !other.max
+          self
+        else
+          case max <=> other.max
+          when 0
+            include_max ? other : self
+          when -1
+            self
+          when 1
+            other
+          end
+        end
+
+      if !min_range.equal?(max_range) && min_range.min && max_range.max
+        case min_range.min <=> max_range.max
+        when -1
+        when 0
+          if !min_range.include_min || !max_range.include_max
+            return EMPTY
+          end
+        when 1
+          return EMPTY
+        end
+      end
+
+      VersionRange.new(
+        min: min_range.min,
+        include_min: min_range.include_min,
+        max: max_range.max,
+        include_max: max_range.include_max
+      )
+    end
+
+    # The span covered by two ranges
+    #
+    # If self and other are contiguous, this builds a union of the two ranges.
+    # (if they aren't you are probably calling the wrong method)
+    def span(other)
+      return self if other.empty?
+
+      min_range =
+        if !min
+          self
+        elsif !other.min
+          other
+        else
+          case min <=> other.min
+          when 0
+            include_min ? self : other
+          when -1
+            self
+          when 1
+            other
+          end
+        end
+
+      max_range =
+        if !max
+          self
+        elsif !other.max
+          other
+        else
+          case max <=> other.max
+          when 0
+            include_max ? self : other
+          when -1
+            other
+          when 1
+            self
+          end
+        end
+
+      VersionRange.new(
+        min: min_range.min,
+        include_min: min_range.include_min,
+        max: max_range.max,
+        include_max: max_range.include_max
+      )
+    end
+
+    def union(other)
+      return other.union(self) if other.is_a?(VersionUnion)
+
+      if contiguous_to?(other)
+        span(other)
+      else
+        VersionUnion.union([self, other])
+      end
+    end
+
+    def contiguous_to?(other)
+      return false if other.empty?
+      return true if any?
+
+      intersects?(other) || contiguous_below?(other) || contiguous_above?(other)
+    end
+
+    def contiguous_below?(other)
+      return false if !max || !other.min
+
+      max == other.min && (include_max || other.include_min)
+    end
+
+    def contiguous_above?(other)
+      other.contiguous_below?(self)
+    end
+
+    def allows_all?(other)
+      return true if other.empty?
+
+      if other.is_a?(VersionUnion)
+        return VersionUnion.new([self]).allows_all?(other)
+      end
+
+      return false if max && !other.max
+      return false if min && !other.min
+
+      if min
+        case min <=> other.min
+        when -1
+        when 0
+          return false if !include_min && other.include_min
+        when 1
+          return false
+        end
+      end
+
+      if max
+        case max <=> other.max
+        when -1
+          return false
+        when 0
+          return false if !include_max && other.include_max
+        when 1
+        end
+      end
+
+      true
+    end
+
+    def any?
+      !min && !max
+    end
+
+    def empty?
+      false
+    end
+
+    def to_s
+      @name ||= constraints.join(", ")
+    end
+
+    def inspect
+      "#<#{self.class} #{to_s}>"
+    end
+
+    def upper_invert
+      return self.class.empty unless max
+
+      VersionRange.new(min: max, include_min: !include_max)
+    end
+
+    def invert
+      return self.class.empty if any?
+
+      low = -> { VersionRange.new(max: min, include_max: !include_min) }
+      high = -> { VersionRange.new(min: max, include_min: !include_max) }
+
+      if !min
+        high.call
+      elsif !max
+        low.call
+      else
+        low.call.union(high.call)
+      end
+    end
+
+    def ==(other)
+      self.class == other.class &&
+        min == other.min &&
+        max == other.max &&
+        include_min == other.include_min &&
+        include_max == other.include_max
+    end
+
+    private
+
+    def constraints
+      return ["any"] if any?
+      return ["= #{min}"] if min.to_s == max.to_s
+
+      c = []
+      c << "#{include_min ? ">=" : ">"} #{min}" if min
+      c << "#{include_max ? "<=" : "<"} #{max}" if max
+      c
+    end
+
+  end
+end
diff --git a/lib/bundler/vendor/pub_grub/lib/pub_grub/version_solver.rb b/lib/bundler/vendor/pub_grub/lib/pub_grub/version_solver.rb
new file mode 100644
index 0000000000..000923e99a
--- /dev/null
+++ b/lib/bundler/vendor/pub_grub/lib/pub_grub/version_solver.rb
@@ -0,0 +1,236 @@
+require_relative 'partial_solution'
+require_relative 'term'
+require_relative 'incompatibility'
+require_relative 'solve_failure'
+require_relative 'strategy'
+
+module Bundler::PubGrub
+  class VersionSolver
+    attr_reader :logger
+    attr_reader :source
+    attr_reader :solution
+    attr_reader :strategy
+
+    def initialize(source:, root: Package.root, strategy: Strategy.new(source), logger: Bundler::PubGrub.logger)
+      @logger = logger
+
+      @source = source
+      @strategy = strategy
+
+      # { package => [incompatibility, ...]}
+      @incompatibilities = Hash.new do |h, k|
+        h[k] = []
+      end
+
+      @seen_incompatibilities = {}
+
+      @solution = PartialSolution.new
+
+      add_incompatibility Incompatibility.new([
+        Term.new(VersionConstraint.any(root), false)
+      ], cause: :root)
+
+      propagate(root)
+    end
+
+    def solved?
+      solution.unsatisfied.empty?
+    end
+
+    # Returns true if there is more work to be done, false otherwise
+    def work
+      unsatisfied_terms = solution.unsatisfied
+      if unsatisfied_terms.empty?
+        logger.info { "Solution found after #{solution.attempted_solutions} attempts:" }
+        solution.decisions.each do |package, version|
+          next if Package.root?(package)
+          logger.info { "* #{package} #{version}" }
+        end
+
+        return false
+      end
+
+      next_package = choose_package_version_from(unsatisfied_terms)
+      propagate(next_package)
+
+      true
+    end
+
+    def solve
+      while work; end
+
+      solution.decisions
+    end
+
+    alias_method :result, :solve
+
+    private
+
+    def propagate(initial_package)
+      changed = [initial_package]
+      while package = changed.shift
+        @incompatibilities[package].reverse_each do |incompatibility|
+          result = propagate_incompatibility(incompatibility)
+          if result == :conflict
+            root_cause = resolve_conflict(incompatibility)
+            changed.clear
+            changed << propagate_incompatibility(root_cause)
+          elsif result # should be a Package
+            changed << result
+          end
+        end
+        changed.uniq!
+      end
+    end
+
+    def propagate_incompatibility(incompatibility)
+      unsatisfied = nil
+      incompatibility.terms.each do |term|
+        relation = solution.relation(term)
+        if relation == :disjoint
+          return nil
+        elsif relation == :overlap
+          # If more than one term is inconclusive, we can't deduce anything
+          return nil if unsatisfied
+          unsatisfied = term
+        end
+      end
+
+      if !unsatisfied
+        return :conflict
+      end
+
+      logger.debug { "derived: #{unsatisfied.invert}" }
+
+      solution.derive(unsatisfied.invert, incompatibility)
+
+      unsatisfied.package
+    end
+
+    def choose_package_version_from(unsatisfied_terms)
+      remaining = unsatisfied_terms.map { |t| [t.package, t.constraint.range] }.to_h
+
+      package, version = strategy.next_package_and_version(remaining)
+
+      logger.debug { "attempting #{package} #{version}" }
+
+      if version.nil?
+        unsatisfied_term = unsatisfied_terms.find { |t| t.package == package }
+        add_incompatibility source.no_versions_incompatibility_for(package, unsatisfied_term)
+        return package
+      end
+
+      conflict = false
+
+      source.incompatibilities_for(package, version).each do |incompatibility|
+        if @seen_incompatibilities.include?(incompatibility)
+          logger.debug { "knew: #{incompatibility}" }
+          next
+        end
+        @seen_incompatibilities[incompatibility] = true
+
+        add_incompatibility incompatibility
+
+        conflict ||= incompatibility.terms.all? do |term|
+          term.package == package || solution.satisfies?(term)
+        end
+      end
+
+      unless conflict
+        logger.info { "selected #{package} #{version}" }
+
+        solution.decide(package, version)
+      else
+        logger.info { "conflict: #{conflict.inspect}" }
+      end
+
+      package
+    end
+
+    def resolve_conflict(incompatibility)
+      logger.info { "conflict: #{incompatibility}" }
+
+      new_incompatibility = nil
+
+      while !incompatibility.failure?
+        most_recent_term = nil
+        most_recent_satisfier = nil
+        difference = nil
+
+        previous_level = 1
+
+        incompatibility.terms.each do |term|
+          satisfier = solution.satisfier(term)
+
+          if most_recent_satisfier.nil?
+            most_recent_term = term
+            most_recent_satisfier = satisfier
+          elsif most_recent_satisfier.index < satisfier.index
+            previous_level = [previous_level, most_recent_satisfier.decision_level].max
+            most_recent_term = term
+            most_recent_satisfier = satisfier
+            difference = nil
+          else
+            previous_level = [previous_level, satisfier.decision_level].max
+          end
+
+          if most_recent_term == term
+            difference = most_recent_satisfier.term.difference(most_recent_term)
+            if difference.empty?
+              difference = nil
+            else
+              difference_satisfier = solution.satisfier(difference.inverse)
+              previous_level = [previous_level, difference_satisfier.decision_level].max
+            end
+          end
+        end
+
+        if previous_level < most_recent_satisfier.decision_level ||
+            most_recent_satisfier.decision?
+
+          logger.info { "backtracking to #{previous_level}" }
+          solution.backtrack(previous_level)
+
+          if new_incompatibility
+            add_incompatibility(new_incompatibility)
+          end
+
+          return incompatibility
+        end
+
+        new_terms = []
+        new_terms += incompatibility.terms - [most_recent_term]
+        new_terms += most_recent_satisfier.cause.terms.reject { |term|
+          term.package == most_recent_satisfier.term.package
+        }
+        if difference
+          new_terms << difference.invert
+        end
+
+        new_incompatibility = Incompatibility.new(new_terms, cause: Incompatibility::ConflictCause.new(incompatibility, most_recent_satisfier.cause))
+
+        if incompatibility.to_s == new_incompatibility.to_s
+          logger.info { "!! failed to resolve conflicts, this shouldn't have happened" }
+          break
+        end
+
+        incompatibility = new_incompatibility
+
+        partially = difference ? " partially" : ""
+        logger.info { "! #{most_recent_term} is#{partially} satisfied by #{most_recent_satisfier.term}" }
+        logger.info { "! which is caused by #{most_recent_satisfier.cause}" }
+        logger.info { "! thus #{incompatibility}" }
+      end
+
+      raise SolveFailure.new(incompatibility)
+    end
+
+    def add_incompatibility(incompatibility)
+      logger.debug { "fact: #{incompatibility}" }
+      incompatibility.terms.each do |term|
+        package = term.package
+        @incompatibilities[package] << incompatibility
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/pub_grub/lib/pub_grub/version_union.rb b/lib/bundler/vendor/pub_grub/lib/pub_grub/version_union.rb
new file mode 100644
index 0000000000..bbc10c3804
--- /dev/null
+++ b/lib/bundler/vendor/pub_grub/lib/pub_grub/version_union.rb
@@ -0,0 +1,178 @@
+# frozen_string_literal: true
+
+module Bundler::PubGrub
+  class VersionUnion
+    attr_reader :ranges
+
+    def self.normalize_ranges(ranges)
+      ranges = ranges.flat_map do |range|
+        range.ranges
+      end
+
+      ranges.reject!(&:empty?)
+
+      return [] if ranges.empty?
+
+      mins, ranges = ranges.partition { |r| !r.min }
+      original_ranges = mins + ranges.sort_by { |r| [r.min, r.include_min ? 0 : 1] }
+      ranges = [original_ranges.shift]
+      original_ranges.each do |range|
+        if ranges.last.contiguous_to?(range)
+          ranges << ranges.pop.span(range)
+        else
+          ranges << range
+        end
+      end
+
+      ranges
+    end
+
+    def self.union(ranges, normalize: true)
+      ranges = normalize_ranges(ranges) if normalize
+
+      if ranges.size == 0
+        VersionRange.empty
+      elsif ranges.size == 1
+        ranges[0]
+      else
+        new(ranges)
+      end
+    end
+
+    def initialize(ranges)
+      raise ArgumentError unless ranges.all? { |r| r.instance_of?(VersionRange) }
+      @ranges = ranges
+    end
+
+    def hash
+      ranges.hash
+    end
+
+    def eql?(other)
+      ranges.eql?(other.ranges)
+    end
+
+    def include?(version)
+      !!ranges.bsearch {|r| r.compare_version(version) }
+    end
+
+    def select_versions(all_versions)
+      versions = []
+      ranges.inject(all_versions) do |acc, range|
+        _, matching, higher = range.partition_versions(acc)
+        versions.concat matching
+        higher
+      end
+      versions
+    end
+
+    def intersects?(other)
+      my_ranges = ranges.dup
+      other_ranges = other.ranges.dup
+
+      my_range = my_ranges.shift
+      other_range = other_ranges.shift
+      while my_range && other_range
+        if my_range.intersects?(other_range)
+          return true
+        end
+
+        if !my_range.max || other_range.empty? || (other_range.max && other_range.max < my_range.max)
+          other_range = other_ranges.shift
+        else
+          my_range = my_ranges.shift
+        end
+      end
+    end
+    alias_method :allows_any?, :intersects?
+
+    def allows_all?(other)
+      my_ranges = ranges.dup
+
+      my_range = my_ranges.shift
+
+      other.ranges.all? do |other_range|
+        while my_range
+          break if my_range.allows_all?(other_range)
+          my_range = my_ranges.shift
+        end
+
+        !!my_range
+      end
+    end
+
+    def empty?
+      false
+    end
+
+    def any?
+      false
+    end
+
+    def intersect(other)
+      my_ranges = ranges.dup
+      other_ranges = other.ranges.dup
+      new_ranges = []
+
+      my_range = my_ranges.shift
+      other_range = other_ranges.shift
+      while my_range && other_range
+        new_ranges << my_range.intersect(other_range)
+
+        if !my_range.max || other_range.empty? || (other_range.max && other_range.max < my_range.max)
+          other_range = other_ranges.shift
+        else
+          my_range = my_ranges.shift
+        end
+      end
+      new_ranges.reject!(&:empty?)
+      VersionUnion.union(new_ranges, normalize: false)
+    end
+
+    def upper_invert
+      ranges.last.upper_invert
+    end
+
+    def invert
+      ranges.map(&:invert).inject(:intersect)
+    end
+
+    def union(other)
+      VersionUnion.union([self, other])
+    end
+
+    def to_s
+      output = []
+
+      ranges = self.ranges.dup
+      while !ranges.empty?
+        ne = []
+        range = ranges.shift
+        while !ranges.empty? && ranges[0].min.to_s == range.max.to_s
+          ne << range.max
+          range = range.span(ranges.shift)
+        end
+
+        ne.map! {|x| "!= #{x}" }
+        if ne.empty?
+          output << range.to_s
+        elsif range.any?
+          output << ne.join(', ')
+        else
+          output << "#{range}, #{ne.join(', ')}"
+        end
+      end
+
+      output.join(" OR ")
+    end
+
+    def inspect
+      "#<#{self.class} #{to_s}>"
+    end
+
+    def ==(other)
+      self.class == other.class &&
+        self.ranges == other.ranges
+    end
+  end
+end
diff --git a/lib/bundler/vendor/securerandom/lib/securerandom.rb b/lib/bundler/vendor/securerandom/lib/securerandom.rb
new file mode 100644
index 0000000000..01b7fa15a6
--- /dev/null
+++ b/lib/bundler/vendor/securerandom/lib/securerandom.rb
@@ -0,0 +1,102 @@
+# -*- coding: us-ascii -*-
+# frozen_string_literal: true
+
+require 'random/formatter'
+
+# == Secure random number generator interface.
+#
+# This library is an interface to secure random number generators which are
+# suitable for generating session keys in HTTP cookies, etc.
+#
+# You can use this library in your application by requiring it:
+#
+#   require 'bundler/vendor/securerandom/lib/securerandom'
+#
+# It supports the following secure random number generators:
+#
+# * openssl
+# * /dev/urandom
+# * Win32
+#
+# Bundler::SecureRandom is extended by the Random::Formatter module which
+# defines the following methods:
+#
+# * alphanumeric
+# * base64
+# * choose
+# * gen_random
+# * hex
+# * rand
+# * random_bytes
+# * random_number
+# * urlsafe_base64
+# * uuid
+#
+# These methods are usable as class methods of Bundler::SecureRandom such as
+# +Bundler::SecureRandom.hex+.
+#
+# If a secure random number generator is not available,
+# +NotImplementedError+ is raised.
+
+module Bundler::SecureRandom
+
+  # The version
+  VERSION = "0.4.1"
+
+  class << self
+    # Returns a random binary string containing +size+ bytes.
+    #
+    # See Random.bytes
+    def bytes(n)
+      return gen_random(n)
+    end
+
+    # Compatibility methods for Ruby 3.2, we can remove this after dropping to support Ruby 3.2
+    def alphanumeric(n = nil, chars: ALPHANUMERIC)
+      n = 16 if n.nil?
+      choose(chars, n)
+    end if RUBY_VERSION < '3.3'
+
+    private
+
+    # :stopdoc:
+
+    # Implementation using OpenSSL
+    def gen_random_openssl(n)
+      return OpenSSL::Random.random_bytes(n)
+    end
+
+    # Implementation using system random device
+    def gen_random_urandom(n)
+      ret = Random.urandom(n)
+      unless ret
+        raise NotImplementedError, "No random device"
+      end
+      unless ret.length == n
+        raise NotImplementedError, "Unexpected partial read from random device: only #{ret.length} for #{n} bytes"
+      end
+      ret
+    end
+
+    begin
+      # Check if Random.urandom is available
+      Random.urandom(1)
+      alias gen_random gen_random_urandom
+    rescue RuntimeError
+      begin
+        require 'openssl'
+      rescue NoMethodError
+        raise NotImplementedError, "No random device"
+      else
+        alias gen_random gen_random_openssl
+      end
+    end
+
+    # :startdoc:
+
+    # Generate random data bytes for Random::Formatter
+    public :gen_random
+  end
+end
+
+Bundler::SecureRandom.extend(Random::Formatter)
diff --git a/lib/bundler/vendor/thor/lib/thor.rb b/lib/bundler/vendor/thor/lib/thor.rb
new file mode 100644
index 0000000000..945bdbd551
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor.rb
@@ -0,0 +1,674 @@
+require_relative "thor/base"
+
+class Bundler::Thor
+  $thor_runner ||= false
+  class << self
+    # Allows for custom "Command" package naming.
+    #
+    # === Parameters
+    # name<String>
+    # options<Hash>
+    #
+    def package_name(name, _ = {})
+      @package_name = name.nil? || name == "" ? nil : name
+    end
+
+    # Sets the default command when thor is executed without an explicit command to be called.
+    #
+    # ==== Parameters
+    # meth<Symbol>:: name of the default command
+    #
+    def default_command(meth = nil)
+      if meth
+        @default_command = meth == :none ? "help" : meth.to_s
+      else
+        @default_command ||= from_superclass(:default_command, "help")
+      end
+    end
+    alias_method :default_task, :default_command
+
+    # Registers another Bundler::Thor subclass as a command.
+    #
+    # ==== Parameters
+    # klass<Class>:: Bundler::Thor subclass to register
+    # command<String>:: Subcommand name to use
+    # usage<String>:: Short usage for the subcommand
+    # description<String>:: Description for the subcommand
+    def register(klass, subcommand_name, usage, description, options = {})
+      if klass <= Bundler::Thor::Group
+        desc usage, description, options
+        define_method(subcommand_name) { |*args| invoke(klass, args) }
+      else
+        desc usage, description, options
+        subcommand subcommand_name, klass
+      end
+    end
+
+    # Defines the usage and the description of the next command.
+    #
+    # ==== Parameters
+    # usage<String>
+    # description<String>
+    # options<String>
+    #
+    def desc(usage, description, options = {})
+      if options[:for]
+        command = find_and_refresh_command(options[:for])
+        command.usage = usage             if usage
+        command.description = description if description
+      else
+        @usage = usage
+        @desc = description
+        @hide = options[:hide] || false
+      end
+    end
+
+    # Defines the long description of the next command.
+    #
+    # Long description is by default indented, line-wrapped and repeated whitespace merged.
+    # In order to print long description verbatim, with indentation and spacing exactly
+    # as found in the code, use the +wrap+ option
+    #
+    #   long_desc 'your very long description', wrap: false
+    #
+    # ==== Parameters
+    # long description<String>
+    # options<Hash>
+    #
+    def long_desc(long_description, options = {})
+      if options[:for]
+        command = find_and_refresh_command(options[:for])
+        command.long_description = long_description if long_description
+      else
+        @long_desc = long_description
+        @long_desc_wrap = options[:wrap] != false
+      end
+    end
+
+    # Maps an input to a command. If you define:
+    #
+    #   map "-T" => "list"
+    #
+    # Running:
+    #
+    #   thor -T
+    #
+    # Will invoke the list command.
+    #
+    # ==== Parameters
+    # Hash[String|Array => Symbol]:: Maps the string or the strings in the array to the given command.
+    #
+    def map(mappings = nil, **kw)
+      @map ||= from_superclass(:map, {})
+
+      if mappings && !kw.empty?
+        mappings = kw.merge!(mappings)
+      else
+        mappings ||= kw
+      end
+      if mappings
+        mappings.each do |key, value|
+          if key.respond_to?(:each)
+            key.each { |subkey| @map[subkey] = value }
+          else
+            @map[key] = value
+          end
+        end
+      end
+
+      @map
+    end
+
+    # Declares the options for the next command to be declared.
+    #
+    # ==== Parameters
+    # Hash[Symbol => Object]:: The hash key is the name of the option and the value
+    # is the type of the option. Can be :string, :array, :hash, :boolean, :numeric
+    # or :required (string). If you give a value, the type of the value is used.
+    #
+    def method_options(options = nil)
+      @method_options ||= {}
+      build_options(options, @method_options) if options
+      @method_options
+    end
+
+    alias_method :options, :method_options
+
+    # Adds an option to the set of method options. If :for is given as option,
+    # it allows you to change the options from a previous defined command.
+    #
+    #   def previous_command
+    #     # magic
+    #   end
+    #
+    #   method_option :foo, :for => :previous_command
+    #
+    #   def next_command
+    #     # magic
+    #   end
+    #
+    # ==== Parameters
+    # name<Symbol>:: The name of the argument.
+    # options<Hash>:: Described below.
+    #
+    # ==== Options
+    # :desc     - Description for the argument.
+    # :required - If the argument is required or not.
+    # :default  - Default value for this argument. It cannot be required and have default values.
+    # :aliases  - Aliases for this option.
+    # :type     - The type of the argument, can be :string, :hash, :array, :numeric or :boolean.
+    # :banner   - String to show on usage notes.
+    # :hide     - If you want to hide this option from the help.
+    #
+    def method_option(name, options = {})
+      unless [ Symbol, String ].any? { |klass| name.is_a?(klass) }
+        raise ArgumentError, "Expected a Symbol or String, got #{name.inspect}"
+      end
+      scope = if options[:for]
+        find_and_refresh_command(options[:for]).options
+      else
+        method_options
+      end
+
+      build_option(name, options, scope)
+    end
+    alias_method :option, :method_option
+
+    # Adds and declares option group for exclusive options in the
+    # block and arguments. You can declare options as the outside of the block.
+    #
+    # If :for is given as option, it allows you to change the options from
+    # a previous defined command.
+    #
+    # ==== Parameters
+    # Array[Bundler::Thor::Option.name]
+    # options<Hash>:: :for is applied for previous defined command.
+    #
+    # ==== Examples
+    #
+    #   exclusive do
+    #     option :one
+    #     option :two
+    #   end
+    #
+    # Or
+    #
+    #   option :one
+    #   option :two
+    #   exclusive :one, :two
+    #
+    # If you give "--one" and "--two" at the same time ExclusiveArgumentsError
+    # will be raised.
+    #
+    def method_exclusive(*args, &block)
+      register_options_relation_for(:method_options,
+                                    :method_exclusive_option_names, *args, &block)
+    end
+    alias_method :exclusive, :method_exclusive
+
+    # Adds and declares option group for required at least one of options in the
+    # block of arguments. You can declare options as the outside of the block.
+    #
+    # If :for is given as option, it allows you to change the options from
+    # a previous defined command.
+    #
+    # ==== Parameters
+    # Array[Bundler::Thor::Option.name]
+    # options<Hash>:: :for is applied for previous defined command.
+    #
+    # ==== Examples
+    #
+    #   at_least_one do
+    #     option :one
+    #     option :two
+    #   end
+    #
+    # Or
+    #
+    #   option :one
+    #   option :two
+    #   at_least_one :one, :two
+    #
+    # If you do not give "--one" and "--two" AtLeastOneRequiredArgumentError
+    # will be raised.
+    #
+    # You can use at_least_one and exclusive at the same time.
+    #
+    #    exclusive do
+    #      at_least_one do
+    #        option :one
+    #        option :two
+    #      end
+    #    end
+    #
+    # Then it is required either only one of "--one" or "--two".
+    #
+    def method_at_least_one(*args, &block)
+      register_options_relation_for(:method_options,
+                                    :method_at_least_one_option_names, *args, &block)
+    end
+    alias_method :at_least_one, :method_at_least_one
+
+    # Prints help information for the given command.
+    #
+    # ==== Parameters
+    # shell<Bundler::Thor::Shell>
+    # command_name<String>
+    #
+    def command_help(shell, command_name)
+      meth = normalize_command_name(command_name)
+      command = all_commands[meth]
+      handle_no_command_error(meth) unless command
+
+      shell.say "Usage:"
+      shell.say "  #{banner(command).split("\n").join("\n  ")}"
+      shell.say
+      class_options_help(shell, nil => command.options.values)
+      print_exclusive_options(shell, command)
+      print_at_least_one_required_options(shell, command)
+
+      if command.long_description
+        shell.say "Description:"
+        if command.wrap_long_description
+          shell.print_wrapped(command.long_description, indent: 2)
+        else
+          shell.say command.long_description
+        end
+      else
+        shell.say command.description
+      end
+    end
+    alias_method :task_help, :command_help
+
+    # Prints help information for this class.
+    #
+    # ==== Parameters
+    # shell<Bundler::Thor::Shell>
+    #
+    def help(shell, subcommand = false)
+      list = printable_commands(true, subcommand)
+      Bundler::Thor::Util.thor_classes_in(self).each do |klass|
+        list += klass.printable_commands(false)
+      end
+      sort_commands!(list)
+
+      if defined?(@package_name) && @package_name
+        shell.say "#{@package_name} commands:"
+      else
+        shell.say "Commands:"
+      end
+
+      shell.print_table(list, indent: 2, truncate: true)
+      shell.say
+      class_options_help(shell)
+      print_exclusive_options(shell)
+      print_at_least_one_required_options(shell)
+    end
+
+    # Returns commands ready to be printed.
+    def printable_commands(all = true, subcommand = false)
+      (all ? all_commands : commands).map do |_, command|
+        next if command.hidden?
+        item = []
+        item << banner(command, false, subcommand)
+        item << (command.description ? "# #{command.description.gsub(/\s+/m, ' ')}" : "")
+        item
+      end.compact
+    end
+    alias_method :printable_tasks, :printable_commands
+
+    def subcommands
+      @subcommands ||= from_superclass(:subcommands, [])
+    end
+    alias_method :subtasks, :subcommands
+
+    def subcommand_classes
+      @subcommand_classes ||= {}
+    end
+
+    def subcommand(subcommand, subcommand_class)
+      subcommands << subcommand.to_s
+      subcommand_class.subcommand_help subcommand
+      subcommand_classes[subcommand.to_s] = subcommand_class
+
+      define_method(subcommand) do |*args|
+        args, opts = Bundler::Thor::Arguments.split(args)
+        invoke_args = [args, opts, {invoked_via_subcommand: true, class_options: options}]
+        invoke_args.unshift "help" if opts.delete("--help") || opts.delete("-h")
+        invoke subcommand_class, *invoke_args
+      end
+      subcommand_class.commands.each do |_meth, command|
+        command.ancestor_name = subcommand
+      end
+    end
+    alias_method :subtask, :subcommand
+
+    # Extend check unknown options to accept a hash of conditions.
+    #
+    # === Parameters
+    # options<Hash>: A hash containing :only and/or :except keys
+    def check_unknown_options!(options = {})
+      @check_unknown_options ||= {}
+      options.each do |key, value|
+        if value
+          @check_unknown_options[key] = Array(value)
+        else
+          @check_unknown_options.delete(key)
+        end
+      end
+      @check_unknown_options
+    end
+
+    # Overwrite check_unknown_options? to take subcommands and options into account.
+    def check_unknown_options?(config) #:nodoc:
+      options = check_unknown_options
+      return false unless options
+
+      command = config[:current_command]
+      return true unless command
+
+      name = command.name
+
+      if subcommands.include?(name)
+        false
+      elsif options[:except]
+        !options[:except].include?(name.to_sym)
+      elsif options[:only]
+        options[:only].include?(name.to_sym)
+      else
+        true
+      end
+    end
+
+    # Stop parsing of options as soon as an unknown option or a regular
+    # argument is encountered.  All remaining arguments are passed to the command.
+    # This is useful if you have a command that can receive arbitrary additional
+    # options, and where those additional options should not be handled by
+    # Bundler::Thor.
+    #
+    # ==== Example
+    #
+    # To better understand how this is useful, let's consider a command that calls
+    # an external command.  A user may want to pass arbitrary options and
+    # arguments to that command.  The command itself also accepts some options,
+    # which should be handled by Bundler::Thor.
+    #
+    #   class_option "verbose",  :type => :boolean
+    #   stop_on_unknown_option! :exec
+    #   check_unknown_options!  :except => :exec
+    #
+    #   desc "exec", "Run a shell command"
+    #   def exec(*args)
+    #     puts "diagnostic output" if options[:verbose]
+    #     Kernel.exec(*args)
+    #   end
+    #
+    # Here +exec+ can be called with +--verbose+ to get diagnostic output,
+    # e.g.:
+    #
+    #   $ thor exec --verbose echo foo
+    #   diagnostic output
+    #   foo
+    #
+    # But if +--verbose+ is given after +echo+, it is passed to +echo+ instead:
+    #
+    #   $ thor exec echo --verbose foo
+    #   --verbose foo
+    #
+    # ==== Parameters
+    # Symbol ...:: A list of commands that should be affected.
+    def stop_on_unknown_option!(*command_names)
+      @stop_on_unknown_option = stop_on_unknown_option | command_names
+    end
+
+    def stop_on_unknown_option?(command) #:nodoc:
+      command && stop_on_unknown_option.include?(command.name.to_sym)
+    end
+
+    # Disable the check for required options for the given commands.
+    # This is useful if you have a command that does not need the required options
+    # to work, like help.
+    #
+    # ==== Parameters
+    # Symbol ...:: A list of commands that should be affected.
+    def disable_required_check!(*command_names)
+      @disable_required_check = disable_required_check | command_names
+    end
+
+    def disable_required_check?(command) #:nodoc:
+      command && disable_required_check.include?(command.name.to_sym)
+    end
+
+    # Checks if a specified command exists.
+    #
+    # ==== Parameters
+    # command_name<String>:: The name of the command to check for existence.
+    #
+    # ==== Returns
+    # Boolean:: +true+ if the command exists, +false+ otherwise.
+    def command_exists?(command_name) #:nodoc:
+      commands.keys.include?(normalize_command_name(command_name))
+    end
+
+  protected
+
+    # Returns this class exclusive options array set.
+    #
+    # ==== Returns
+    # Array[Array[Bundler::Thor::Option.name]]
+    #
+    def method_exclusive_option_names #:nodoc:
+      @method_exclusive_option_names ||= []
+    end
+
+    # Returns this class at least one of required options array set.
+    #
+    # ==== Returns
+    # Array[Array[Bundler::Thor::Option.name]]
+    #
+    def method_at_least_one_option_names #:nodoc:
+      @method_at_least_one_option_names ||= []
+    end
+
+    def stop_on_unknown_option #:nodoc:
+      @stop_on_unknown_option ||= []
+    end
+
+    # help command has the required check disabled by default.
+    def disable_required_check #:nodoc:
+      @disable_required_check ||= [:help]
+    end
+
+    def print_exclusive_options(shell, command = nil) # :nodoc:
+      opts = []
+      opts  = command.method_exclusive_option_names unless command.nil?
+      opts += class_exclusive_option_names
+      unless opts.empty?
+        shell.say "Exclusive Options:"
+        shell.print_table(opts.map{ |ex| ex.map{ |e| "--#{e}"}}, indent: 2 )
+        shell.say
+      end
+    end
+
+    def print_at_least_one_required_options(shell, command = nil) # :nodoc:
+      opts = []
+      opts = command.method_at_least_one_option_names unless command.nil?
+      opts += class_at_least_one_option_names
+      unless opts.empty?
+        shell.say "Required At Least One:"
+        shell.print_table(opts.map{ |ex| ex.map{ |e| "--#{e}"}}, indent: 2 )
+        shell.say
+      end
+    end
+
+    # The method responsible for dispatching given the args.
+    def dispatch(meth, given_args, given_opts, config) #:nodoc:
+      meth ||= retrieve_command_name(given_args)
+      command = all_commands[normalize_command_name(meth)]
+
+      if !command && config[:invoked_via_subcommand]
+        # We're a subcommand and our first argument didn't match any of our
+        # commands. So we put it back and call our default command.
+        given_args.unshift(meth)
+        command = all_commands[normalize_command_name(default_command)]
+      end
+
+      if command
+        args, opts = Bundler::Thor::Options.split(given_args)
+        if stop_on_unknown_option?(command) && !args.empty?
+          # given_args starts with a non-option, so we treat everything as
+          # ordinary arguments
+          args.concat opts
+          opts.clear
+        end
+      else
+        args = given_args
+        opts = nil
+        command = dynamic_command_class.new(meth)
+      end
+
+      opts = given_opts || opts || []
+      config[:current_command] = command
+      config[:command_options] = command.options
+
+      instance = new(args, opts, config)
+      yield instance if block_given?
+      args = instance.args
+      trailing = args[Range.new(arguments.size, -1)]
+      instance.invoke_command(command, trailing || [])
+    end
+
+    # The banner for this class. You can customize it if you are invoking the
+    # thor class by another ways which is not the Bundler::Thor::Runner. It receives
+    # the command that is going to be invoked and a boolean which indicates if
+    # the namespace should be displayed as arguments.
+    #
+    def banner(command, namespace = nil, subcommand = false)
+      command.formatted_usage(self, $thor_runner, subcommand).split("\n").map do |formatted_usage|
+        "#{basename} #{formatted_usage}"
+      end.join("\n")
+    end
+
+    def baseclass #:nodoc:
+      Bundler::Thor
+    end
+
+    def dynamic_command_class #:nodoc:
+      Bundler::Thor::DynamicCommand
+    end
+
+    def create_command(meth) #:nodoc:
+      @usage ||= nil
+      @desc ||= nil
+      @long_desc ||= nil
+      @long_desc_wrap ||= nil
+      @hide ||= nil
+
+      if @usage && @desc
+        base_class = @hide ? Bundler::Thor::HiddenCommand : Bundler::Thor::Command
+        relations = {exclusive_option_names: method_exclusive_option_names,
+          at_least_one_option_names: method_at_least_one_option_names}
+        commands[meth] = base_class.new(meth, @desc, @long_desc, @long_desc_wrap, @usage, method_options, relations)
+        @usage, @desc, @long_desc, @long_desc_wrap, @method_options, @hide = nil
+        @method_exclusive_option_names, @method_at_least_one_option_names = nil
+        true
+      elsif all_commands[meth] || meth == "method_missing"
+        true
+      else
+        puts "[WARNING] Attempted to create command #{meth.inspect} without usage or description. " \
+             "Call desc if you want this method to be available as command or declare it inside a " \
+             "no_commands{} block. Invoked from #{caller[1].inspect}."
+        false
+      end
+    end
+    alias_method :create_task, :create_command
+
+    def initialize_added #:nodoc:
+      class_options.merge!(method_options)
+      @method_options = nil
+    end
+
+    # Retrieve the command name from given args.
+    def retrieve_command_name(args) #:nodoc:
+      meth = args.first.to_s unless args.empty?
+      args.shift if meth && (map[meth] || meth !~ /^\-/)
+    end
+    alias_method :retrieve_task_name, :retrieve_command_name
+
+    # receives a (possibly nil) command name and returns a name that is in
+    # the commands hash. In addition to normalizing aliases, this logic
+    # will determine if a shortened command is an unambiguous substring of
+    # a command or alias.
+    #
+    # +normalize_command_name+ also converts names like +animal-prison+
+    # into +animal_prison+.
+    def normalize_command_name(meth) #:nodoc:
+      return default_command.to_s.tr("-", "_") unless meth
+
+      possibilities = find_command_possibilities(meth)
+      raise AmbiguousTaskError, "Ambiguous command #{meth} matches [#{possibilities.join(', ')}]" if possibilities.size > 1
+
+      if possibilities.empty?
+        meth ||= default_command
+      elsif map[meth]
+        meth = map[meth]
+      else
+        meth = possibilities.first
+      end
+
+      meth.to_s.tr("-", "_") # treat foo-bar as foo_bar
+    end
+    alias_method :normalize_task_name, :normalize_command_name
+
+    # this is the logic that takes the command name passed in by the user
+    # and determines whether it is an unambiguous substrings of a command or
+    # alias name.
+    def find_command_possibilities(meth)
+      len = meth.to_s.length
+      possibilities = all_commands.reject { |_k, c| c.hidden? }.merge(map).keys.select { |n| meth == n[0, len] }.sort
+      unique_possibilities = possibilities.map { |k| map[k] || k }.uniq
+
+      if possibilities.include?(meth)
+        [meth]
+      elsif unique_possibilities.size == 1
+        unique_possibilities
+      else
+        possibilities
+      end
+    end
+    alias_method :find_task_possibilities, :find_command_possibilities
+
+    def subcommand_help(cmd)
+      desc "help [COMMAND]", "Describe subcommands or one specific subcommand"
+      class_eval "
+        def help(command = nil, subcommand = true); super; end
+"
+    end
+    alias_method :subtask_help, :subcommand_help
+
+    # Sort the commands, lexicographically by default.
+    #
+    # Can be overridden in the subclass to change the display order of the
+    # commands.
+    def sort_commands!(list)
+      list.sort! { |a, b| a[0] <=> b[0] }
+    end
+  end
+
+  include Bundler::Thor::Base
+
+  map HELP_MAPPINGS => :help
+
+  desc "help [COMMAND]", "Describe available commands or one specific command"
+  def help(command = nil, subcommand = false)
+    if command
+      if self.class.subcommands.include? command
+        self.class.subcommand_classes[command].help(shell, true)
+      else
+        self.class.command_help(shell, command)
+      end
+    else
+      self.class.help(shell, subcommand)
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/actions.rb b/lib/bundler/vendor/thor/lib/thor/actions.rb
new file mode 100644
index 0000000000..ca58182691
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/actions.rb
@@ -0,0 +1,340 @@
+require_relative "actions/create_file"
+require_relative "actions/create_link"
+require_relative "actions/directory"
+require_relative "actions/empty_directory"
+require_relative "actions/file_manipulation"
+require_relative "actions/inject_into_file"
+
+class Bundler::Thor
+  module Actions
+    attr_accessor :behavior
+
+    def self.included(base) #:nodoc:
+      super(base)
+      base.extend ClassMethods
+    end
+
+    module ClassMethods
+      # Hold source paths for one Bundler::Thor instance. source_paths_for_search is the
+      # method responsible to gather source_paths from this current class,
+      # inherited paths and the source root.
+      #
+      def source_paths
+        @_source_paths ||= []
+      end
+
+      # Stores and return the source root for this class
+      def source_root(path = nil)
+        @_source_root = path if path
+        @_source_root ||= nil
+      end
+
+      # Returns the source paths in the following order:
+      #
+      #   1) This class source paths
+      #   2) Source root
+      #   3) Parents source paths
+      #
+      def source_paths_for_search
+        paths = []
+        paths += source_paths
+        paths << source_root if source_root
+        paths += from_superclass(:source_paths, [])
+        paths
+      end
+
+      # Add runtime options that help actions execution.
+      #
+      def add_runtime_options!
+        class_option :force, type: :boolean, aliases: "-f", group: :runtime,
+                             desc: "Overwrite files that already exist"
+
+        class_option :pretend, type: :boolean, aliases: "-p", group: :runtime,
+                               desc: "Run but do not make any changes"
+
+        class_option :quiet, type: :boolean, aliases: "-q", group: :runtime,
+                             desc: "Suppress status output"
+
+        class_option :skip, type: :boolean, aliases: "-s", group: :runtime,
+                            desc: "Skip files that already exist"
+      end
+    end
+
+    # Extends initializer to add more configuration options.
+    #
+    # ==== Configuration
+    # behavior<Symbol>:: The actions default behavior. Can be :invoke or :revoke.
+    #                    It also accepts :force, :skip and :pretend to set the behavior
+    #                    and the respective option.
+    #
+    # destination_root<String>:: The root directory needed for some actions.
+    #
+    def initialize(args = [], options = {}, config = {})
+      self.behavior = case config[:behavior].to_s
+      when "force", "skip"
+        _cleanup_options_and_set(options, config[:behavior])
+        :invoke
+      when "revoke"
+        :revoke
+      else
+        :invoke
+      end
+
+      super
+      self.destination_root = config[:destination_root]
+    end
+
+    # Wraps an action object and call it accordingly to the thor class behavior.
+    #
+    def action(instance) #:nodoc:
+      if behavior == :revoke
+        instance.revoke!
+      else
+        instance.invoke!
+      end
+    end
+
+    # Returns the root for this thor class (also aliased as destination root).
+    #
+    def destination_root
+      @destination_stack.last
+    end
+
+    # Sets the root for this thor class. Relatives path are added to the
+    # directory where the script was invoked and expanded.
+    #
+    def destination_root=(root)
+      @destination_stack ||= []
+      @destination_stack[0] = File.expand_path(root || "")
+    end
+
+    # Returns the given path relative to the absolute root (ie, root where
+    # the script started).
+    #
+    def relative_to_original_destination_root(path, remove_dot = true)
+      root = @destination_stack[0]
+      if path.start_with?(root) && [File::SEPARATOR, File::ALT_SEPARATOR, nil, ""].include?(path[root.size..root.size])
+        path = path.dup
+        path[0...root.size] = "."
+        remove_dot ? (path[2..-1] || "") : path
+      else
+        path
+      end
+    end
+
+    # Holds source paths in instance so they can be manipulated.
+    #
+    def source_paths
+      @source_paths ||= self.class.source_paths_for_search
+    end
+
+    # Receives a file or directory and search for it in the source paths.
+    #
+    def find_in_source_paths(file)
+      possible_files = [file, file + TEMPLATE_EXTNAME]
+      relative_root = relative_to_original_destination_root(destination_root, false)
+
+      source_paths.each do |source|
+        possible_files.each do |f|
+          source_file = File.expand_path(f, File.join(source, relative_root))
+          return source_file if File.exist?(source_file)
+        end
+      end
+
+      message = "Could not find #{file.inspect} in any of your source paths. ".dup
+
+      unless self.class.source_root
+        message << "Please invoke #{self.class.name}.source_root(PATH) with the PATH containing your templates. "
+      end
+
+      message << if source_paths.empty?
+                   "Currently you have no source paths."
+                 else
+                   "Your current source paths are: \n#{source_paths.join("\n")}"
+                 end
+
+      raise Error, message
+    end
+
+    # Do something in the root or on a provided subfolder. If a relative path
+    # is given it's referenced from the current root. The full path is yielded
+    # to the block you provide. The path is set back to the previous path when
+    # the method exits.
+    #
+    # Returns the value yielded by the block.
+    #
+    # ==== Parameters
+    # dir<String>:: the directory to move to.
+    # config<Hash>:: give :verbose => true to log and use padding.
+    #
+    def inside(dir = "", config = {}, &block)
+      verbose = config.fetch(:verbose, false)
+      pretend = options[:pretend]
+
+      say_status :inside, dir, verbose
+      shell.padding += 1 if verbose
+      @destination_stack.push File.expand_path(dir, destination_root)
+
+      # If the directory doesn't exist and we're not pretending
+      if !File.exist?(destination_root) && !pretend
+        require "fileutils"
+        FileUtils.mkdir_p(destination_root)
+      end
+
+      result = nil
+      if pretend
+        # In pretend mode, just yield down to the block
+        result = block.arity == 1 ? yield(destination_root) : yield
+      else
+        require "fileutils"
+        FileUtils.cd(destination_root) { result = block.arity == 1 ? yield(destination_root) : yield }
+      end
+
+      @destination_stack.pop
+      shell.padding -= 1 if verbose
+      result
+    end
+
+    # Goes to the root and execute the given block.
+    #
+    def in_root
+      inside(@destination_stack.first) { yield }
+    end
+
+    # Loads an external file and execute it in the instance binding.
+    #
+    # ==== Parameters
+    # path<String>:: The path to the file to execute. Can be a web address or
+    #                a relative path from the source root.
+    #
+    # ==== Examples
+    #
+    #   apply "http://gist.github.com/103208"
+    #
+    #   apply "recipes/jquery.rb"
+    #
+    def apply(path, config = {})
+      verbose = config.fetch(:verbose, true)
+      is_uri  = path =~ %r{^https?\://}
+      path    = find_in_source_paths(path) unless is_uri
+
+      say_status :apply, path, verbose
+      shell.padding += 1 if verbose
+
+      contents = if is_uri
+        require "open-uri"
+        URI.open(path, "Accept" => "application/x-thor-template", &:read)
+      else
+        File.open(path, &:read)
+      end
+
+      instance_eval(contents, path)
+      shell.padding -= 1 if verbose
+    end
+
+    # Executes a command returning the contents of the command.
+    #
+    # ==== Parameters
+    # command<String>:: the command to be executed.
+    # config<Hash>:: give :verbose => false to not log the status, :capture => true to hide to output. Specify :with
+    #                to append an executable to command execution.
+    #
+    # ==== Example
+    #
+    #   inside('vendor') do
+    #     run('ln -s ~/edge rails')
+    #   end
+    #
+    def run(command, config = {})
+      return unless behavior == :invoke
+
+      destination = relative_to_original_destination_root(destination_root, false)
+      desc = "#{command} from #{destination.inspect}"
+
+      if config[:with]
+        desc = "#{File.basename(config[:with].to_s)} #{desc}"
+        command = "#{config[:with]} #{command}"
+      end
+
+      say_status :run, desc, config.fetch(:verbose, true)
+
+      return if options[:pretend]
+
+      env_splat = [config[:env]] if config[:env]
+
+      if config[:capture]
+        require "open3"
+        result, status = Open3.capture2e(*env_splat, command.to_s)
+        success = status.success?
+      else
+        result = system(*env_splat, command.to_s)
+        success = result
+      end
+
+      abort if !success && config.fetch(:abort_on_failure, self.class.exit_on_failure?)
+
+      result
+    end
+
+    # Executes a ruby script (taking into account WIN32 platform quirks).
+    #
+    # ==== Parameters
+    # command<String>:: the command to be executed.
+    # config<Hash>:: give :verbose => false to not log the status.
+    #
+    def run_ruby_script(command, config = {})
+      return unless behavior == :invoke
+      run command, config.merge(with: Bundler::Thor::Util.ruby_command)
+    end
+
+    # Run a thor command. A hash of options can be given and it's converted to
+    # switches.
+    #
+    # ==== Parameters
+    # command<String>:: the command to be invoked
+    # args<Array>:: arguments to the command
+    # config<Hash>:: give :verbose => false to not log the status, :capture => true to hide to output.
+    #                Other options are given as parameter to Bundler::Thor.
+    #
+    #
+    # ==== Examples
+    #
+    #   thor :install, "http://gist.github.com/103208"
+    #   #=> thor install http://gist.github.com/103208
+    #
+    #   thor :list, :all => true, :substring => 'rails'
+    #   #=> thor list --all --substring=rails
+    #
+    def thor(command, *args)
+      config  = args.last.is_a?(Hash) ? args.pop : {}
+      verbose = config.key?(:verbose) ? config.delete(:verbose) : true
+      pretend = config.key?(:pretend) ? config.delete(:pretend) : false
+      capture = config.key?(:capture) ? config.delete(:capture) : false
+
+      args.unshift(command)
+      args.push Bundler::Thor::Options.to_switches(config)
+      command = args.join(" ").strip
+
+      run command, with: :thor, verbose: verbose, pretend: pretend, capture: capture
+    end
+
+  protected
+
+    # Allow current root to be shared between invocations.
+    #
+    def _shared_configuration #:nodoc:
+      super.merge!(destination_root: destination_root)
+    end
+
+    def _cleanup_options_and_set(options, key) #:nodoc:
+      case options
+      when Array
+        %w(--force -f --skip -s).each { |i| options.delete(i) }
+        options << "--#{key}"
+      when Hash
+        [:force, :skip, "force", "skip"].each { |i| options.delete(i) }
+        options.merge!(key => true)
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/actions/create_file.rb b/lib/bundler/vendor/thor/lib/thor/actions/create_file.rb
new file mode 100644
index 0000000000..6724835b01
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/actions/create_file.rb
@@ -0,0 +1,105 @@
+require_relative "empty_directory"
+
+class Bundler::Thor
+  module Actions
+    # Create a new file relative to the destination root with the given data,
+    # which is the return value of a block or a data string.
+    #
+    # ==== Parameters
+    # destination<String>:: the relative path to the destination root.
+    # data<String|NilClass>:: the data to append to the file.
+    # config<Hash>:: give :verbose => false to not log the status.
+    #
+    # ==== Examples
+    #
+    #   create_file "lib/fun_party.rb" do
+    #     hostname = ask("What is the virtual hostname I should use?")
+    #     "vhost.name = #{hostname}"
+    #   end
+    #
+    #   create_file "config/apache.conf", "your apache config"
+    #
+    def create_file(destination, *args, &block)
+      config = args.last.is_a?(Hash) ? args.pop : {}
+      data = args.first
+      action CreateFile.new(self, destination, block || data.to_s, config)
+    end
+    alias_method :add_file, :create_file
+
+    # CreateFile is a subset of Template, which instead of rendering a file with
+    # ERB, it gets the content from the user.
+    #
+    class CreateFile < EmptyDirectory #:nodoc:
+      attr_reader :data
+
+      def initialize(base, destination, data, config = {})
+        @data = data
+        super(base, destination, config)
+      end
+
+      # Checks if the content of the file at the destination is identical to the rendered result.
+      #
+      # ==== Returns
+      # Boolean:: true if it is identical, false otherwise.
+      #
+      def identical?
+        # binread uses ASCII-8BIT, so to avoid false negatives, the string must use the same
+        exists? && File.binread(destination) == String.new(render).force_encoding("ASCII-8BIT")
+      end
+
+      # Holds the content to be added to the file.
+      #
+      def render
+        @render ||= if data.is_a?(Proc)
+          data.call
+        else
+          data
+        end
+      end
+
+      def invoke!
+        invoke_with_conflict_check do
+          require "fileutils"
+          FileUtils.mkdir_p(File.dirname(destination))
+          File.open(destination, "wb", config[:perm]) { |f| f.write render }
+        end
+        given_destination
+      end
+
+    protected
+
+      # Now on conflict we check if the file is identical or not.
+      #
+      def on_conflict_behavior(&block)
+        if identical?
+          say_status :identical, :blue
+        else
+          options = base.options.merge(config)
+          force_or_skip_or_conflict(options[:force], options[:skip], &block)
+        end
+      end
+
+      # If force is true, run the action, otherwise check if it's not being
+      # skipped. If both are false, show the file_collision menu, if the menu
+      # returns true, force it, otherwise skip.
+      #
+      def force_or_skip_or_conflict(force, skip, &block)
+        if force
+          say_status :force, :yellow
+          yield unless pretend?
+        elsif skip
+          say_status :skip, :yellow
+        else
+          say_status :conflict, :red
+          force_or_skip_or_conflict(force_on_collision?, true, &block)
+        end
+      end
+
+      # Shows the file collision menu to the user and gets the result.
+      #
+      def force_on_collision?
+        base.shell.file_collision(destination) { render }
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/actions/create_link.rb b/lib/bundler/vendor/thor/lib/thor/actions/create_link.rb
new file mode 100644
index 0000000000..fb76fcdbe9
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/actions/create_link.rb
@@ -0,0 +1,61 @@
+require_relative "create_file"
+
+class Bundler::Thor
+  module Actions
+    # Create a new file relative to the destination root from the given source.
+    #
+    # ==== Parameters
+    # destination<String>:: the relative path to the destination root.
+    # source<String|NilClass>:: the relative path to the source root.
+    # config<Hash>:: give :verbose => false to not log the status.
+    #   :: give :symbolic => false for hard link.
+    #
+    # ==== Examples
+    #
+    #   create_link "config/apache.conf", "/etc/apache.conf"
+    #
+    def create_link(destination, *args)
+      config = args.last.is_a?(Hash) ? args.pop : {}
+      source = args.first
+      action CreateLink.new(self, destination, source, config)
+    end
+    alias_method :add_link, :create_link
+
+    # CreateLink is a subset of CreateFile, which instead of taking a block of
+    # data, just takes a source string from the user.
+    #
+    class CreateLink < CreateFile #:nodoc:
+      attr_reader :data
+
+      # Checks if the content of the file at the destination is identical to the rendered result.
+      #
+      # ==== Returns
+      # Boolean:: true if it is identical, false otherwise.
+      #
+      def identical?
+        source = File.expand_path(render, File.dirname(destination))
+        exists? && File.identical?(source, destination)
+      end
+
+      def invoke!
+        invoke_with_conflict_check do
+          require "fileutils"
+          FileUtils.mkdir_p(File.dirname(destination))
+          # Create a symlink by default
+          config[:symbolic] = true if config[:symbolic].nil?
+          File.unlink(destination) if exists?
+          if config[:symbolic]
+            File.symlink(render, destination)
+          else
+            File.link(render, destination)
+          end
+        end
+        given_destination
+      end
+
+      def exists?
+        super || File.symlink?(destination)
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/actions/directory.rb b/lib/bundler/vendor/thor/lib/thor/actions/directory.rb
new file mode 100644
index 0000000000..2f9687c0a5
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/actions/directory.rb
@@ -0,0 +1,108 @@
+require_relative "empty_directory"
+
+class Bundler::Thor
+  module Actions
+    # Copies recursively the files from source directory to root directory.
+    # If any of the files finishes with .tt, it's considered to be a template
+    # and is placed in the destination without the extension .tt. If any
+    # empty directory is found, it's copied and all .empty_directory files are
+    # ignored. If any file name is wrapped within % signs, the text within
+    # the % signs will be executed as a method and replaced with the returned
+    # value. Let's suppose a doc directory with the following files:
+    #
+    #   doc/
+    #     components/.empty_directory
+    #     README
+    #     rdoc.rb.tt
+    #     %app_name%.rb
+    #
+    # When invoked as:
+    #
+    #   directory "doc"
+    #
+    # It will create a doc directory in the destination with the following
+    # files (assuming that the `app_name` method returns the value "blog"):
+    #
+    #   doc/
+    #     components/
+    #     README
+    #     rdoc.rb
+    #     blog.rb
+    #
+    # <b>Encoded path note:</b> Since Bundler::Thor internals use Object#respond_to? to check if it can
+    # expand %something%, this `something` should be a public method in the class calling
+    # #directory. If a method is private, Bundler::Thor stack raises PrivateMethodEncodedError.
+    #
+    # ==== Parameters
+    # source<String>:: the relative path to the source root.
+    # destination<String>:: the relative path to the destination root.
+    # config<Hash>:: give :verbose => false to not log the status.
+    #                If :recursive => false, does not look for paths recursively.
+    #                If :mode => :preserve, preserve the file mode from the source.
+    #                If :exclude_pattern => /regexp/, prevents copying files that match that regexp.
+    #
+    # ==== Examples
+    #
+    #   directory "doc"
+    #   directory "doc", "docs", :recursive => false
+    #
+    def directory(source, *args, &block)
+      config = args.last.is_a?(Hash) ? args.pop : {}
+      destination = args.first || source
+      action Directory.new(self, source, destination || source, config, &block)
+    end
+
+    class Directory < EmptyDirectory #:nodoc:
+      attr_reader :source
+
+      def initialize(base, source, destination = nil, config = {}, &block)
+        @source = File.expand_path(Dir[Util.escape_globs(base.find_in_source_paths(source.to_s))].first)
+        @block  = block
+        super(base, destination, {recursive: true}.merge(config))
+      end
+
+      def invoke!
+        base.empty_directory given_destination, config
+        execute!
+      end
+
+      def revoke!
+        execute!
+      end
+
+    protected
+
+      def execute!
+        lookup = Util.escape_globs(source)
+        lookup = config[:recursive] ? File.join(lookup, "**") : lookup
+        lookup = file_level_lookup(lookup)
+
+        files(lookup).sort.each do |file_source|
+          next if File.directory?(file_source)
+          next if config[:exclude_pattern] && file_source.match(config[:exclude_pattern])
+          file_destination = File.join(given_destination, file_source.gsub(source, "."))
+          file_destination.gsub!("/./", "/")
+
+          case file_source
+          when /\.empty_directory$/
+            dirname = File.dirname(file_destination).gsub(%r{/\.$}, "")
+            next if dirname == given_destination
+            base.empty_directory(dirname, config)
+          when /#{TEMPLATE_EXTNAME}$/
+            base.template(file_source, file_destination[0..-4], config, &@block)
+          else
+            base.copy_file(file_source, file_destination, config, &@block)
+          end
+        end
+      end
+
+      def file_level_lookup(previous_lookup)
+        File.join(previous_lookup, "*")
+      end
+
+      def files(lookup)
+        Dir.glob(lookup, File::FNM_DOTMATCH)
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/actions/empty_directory.rb b/lib/bundler/vendor/thor/lib/thor/actions/empty_directory.rb
new file mode 100644
index 0000000000..c0bca78525
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/actions/empty_directory.rb
@@ -0,0 +1,143 @@
+class Bundler::Thor
+  module Actions
+    # Creates an empty directory.
+    #
+    # ==== Parameters
+    # destination<String>:: the relative path to the destination root.
+    # config<Hash>:: give :verbose => false to not log the status.
+    #
+    # ==== Examples
+    #
+    #   empty_directory "doc"
+    #
+    def empty_directory(destination, config = {})
+      action EmptyDirectory.new(self, destination, config)
+    end
+
+    # Class which holds create directory logic. This is the base class for
+    # other actions like create_file and directory.
+    #
+    # This implementation is based in Templater actions, created by Jonas Nicklas
+    # and Michael S. Klishin under MIT LICENSE.
+    #
+    class EmptyDirectory #:nodoc:
+      attr_reader :base, :destination, :given_destination, :relative_destination, :config
+
+      # Initializes given the source and destination.
+      #
+      # ==== Parameters
+      # base<Bundler::Thor::Base>:: A Bundler::Thor::Base instance
+      # source<String>:: Relative path to the source of this file
+      # destination<String>:: Relative path to the destination of this file
+      # config<Hash>:: give :verbose => false to not log the status.
+      #
+      def initialize(base, destination, config = {})
+        @base = base
+        @config = {verbose: true}.merge(config)
+        self.destination = destination
+      end
+
+      # Checks if the destination file already exists.
+      #
+      # ==== Returns
+      # Boolean:: true if the file exists, false otherwise.
+      #
+      def exists?
+        ::File.exist?(destination)
+      end
+
+      def invoke!
+        invoke_with_conflict_check do
+          require "fileutils"
+          ::FileUtils.mkdir_p(destination)
+        end
+      end
+
+      def revoke!
+        say_status :remove, :red
+        require "fileutils"
+        ::FileUtils.rm_rf(destination) if !pretend? && exists?
+        given_destination
+      end
+
+    protected
+
+      # Shortcut for pretend.
+      #
+      def pretend?
+        base.options[:pretend]
+      end
+
+      # Sets the absolute destination value from a relative destination value.
+      # It also stores the given and relative destination. Let's suppose our
+      # script is being executed on "dest", it sets the destination root to
+      # "dest". The destination, given_destination and relative_destination
+      # are related in the following way:
+      #
+      #   inside "bar" do
+      #     empty_directory "baz"
+      #   end
+      #
+      #   destination          #=> dest/bar/baz
+      #   relative_destination #=> bar/baz
+      #   given_destination    #=> baz
+      #
+      def destination=(destination)
+        return unless destination
+        @given_destination = convert_encoded_instructions(destination.to_s)
+        @destination = ::File.expand_path(@given_destination, base.destination_root)
+        @relative_destination = base.relative_to_original_destination_root(@destination)
+      end
+
+      # Filenames in the encoded form are converted. If you have a file:
+      #
+      #   %file_name%.rb
+      #
+      # It calls #file_name from the base and replaces %-string with the
+      # return value (should be String) of #file_name:
+      #
+      #   user.rb
+      #
+      # The method referenced can be either public or private.
+      #
+      def convert_encoded_instructions(filename)
+        filename.gsub(/%(.*?)%/) do |initial_string|
+          method = $1.strip
+          base.respond_to?(method, true) ? base.send(method) : initial_string
+        end
+      end
+
+      # Receives a hash of options and just execute the block if some
+      # conditions are met.
+      #
+      def invoke_with_conflict_check(&block)
+        if exists?
+          on_conflict_behavior(&block)
+        else
+          yield unless pretend?
+          say_status :create, :green
+        end
+
+        destination
+      rescue Errno::EISDIR, Errno::EEXIST
+        on_file_clash_behavior
+      end
+
+      def on_file_clash_behavior
+        say_status :file_clash, :red
+      end
+
+      # What to do when the destination file already exists.
+      #
+      def on_conflict_behavior
+        say_status :exist, :blue
+      end
+
+      # Shortcut to say_status shell method.
+      #
+      def say_status(status, color)
+        base.shell.say_status status, relative_destination, color if config[:verbose]
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb b/lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb
new file mode 100644
index 0000000000..d8c9863054
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb
@@ -0,0 +1,407 @@
+require "erb"
+
+class Bundler::Thor
+  module Actions
+    # Copies the file from the relative source to the relative destination. If
+    # the destination is not given it's assumed to be equal to the source.
+    #
+    # ==== Parameters
+    # source<String>:: the relative path to the source root.
+    # destination<String>:: the relative path to the destination root.
+    # config<Hash>:: give :verbose => false to not log the status, and
+    #                :mode => :preserve, to preserve the file mode from the source.
+    #
+    # ==== Examples
+    #
+    #   copy_file "README", "doc/README"
+    #
+    #   copy_file "doc/README"
+    #
+    def copy_file(source, *args, &block)
+      config = args.last.is_a?(Hash) ? args.pop : {}
+      destination = args.first || source
+      source = File.expand_path(find_in_source_paths(source.to_s))
+
+      resulting_destination = create_file destination, nil, config do
+        content = File.binread(source)
+        content = yield(content) if block
+        content
+      end
+      if config[:mode] == :preserve
+        mode = File.stat(source).mode
+        chmod(resulting_destination, mode, config)
+      end
+    end
+
+    # Links the file from the relative source to the relative destination. If
+    # the destination is not given it's assumed to be equal to the source.
+    #
+    # ==== Parameters
+    # source<String>:: the relative path to the source root.
+    # destination<String>:: the relative path to the destination root.
+    # config<Hash>:: give :verbose => false to not log the status.
+    #
+    # ==== Examples
+    #
+    #   link_file "README", "doc/README"
+    #
+    #   link_file "doc/README"
+    #
+    def link_file(source, *args)
+      config = args.last.is_a?(Hash) ? args.pop : {}
+      destination = args.first || source
+      source = File.expand_path(find_in_source_paths(source.to_s))
+
+      create_link destination, source, config
+    end
+
+    # Gets the content at the given address and places it at the given relative
+    # destination. If a block is given instead of destination, the content of
+    # the url is yielded and used as location.
+    #
+    # +get+ relies on open-uri, so passing application user input would provide
+    # a command injection attack vector.
+    #
+    # ==== Parameters
+    # source<String>:: the address of the given content.
+    # destination<String>:: the relative path to the destination root.
+    # config<Hash>:: give :verbose => false to not log the status, and
+    #                :http_headers => <Hash> to add headers to an http request.
+    #
+    # ==== Examples
+    #
+    #   get "http://gist.github.com/103208", "doc/README"
+    #
+    #   get "http://gist.github.com/103208", "doc/README", :http_headers => {"Content-Type" => "application/json"}
+    #
+    #   get "http://gist.github.com/103208" do |content|
+    #     content.split("\n").first
+    #   end
+    #
+    def get(source, *args, &block)
+      config = args.last.is_a?(Hash) ? args.pop : {}
+      destination = args.first
+
+      render = if source =~ %r{^https?\://}
+        require "open-uri"
+        URI.send(:open, source, config.fetch(:http_headers, {})) { |input| input.binmode.read }
+      else
+        source = File.expand_path(find_in_source_paths(source.to_s))
+        File.open(source) { |input| input.binmode.read }
+      end
+
+      destination ||= if block_given?
+        block.arity == 1 ? yield(render) : yield
+      else
+        File.basename(source)
+      end
+
+      create_file destination, render, config
+    end
+
+    # Gets an ERB template at the relative source, executes it and makes a copy
+    # at the relative destination. If the destination is not given it's assumed
+    # to be equal to the source removing .tt from the filename.
+    #
+    # ==== Parameters
+    # source<String>:: the relative path to the source root.
+    # destination<String>:: the relative path to the destination root.
+    # config<Hash>:: give :verbose => false to not log the status.
+    #
+    # ==== Examples
+    #
+    #   template "README", "doc/README"
+    #
+    #   template "doc/README"
+    #
+    def template(source, *args, &block)
+      config = args.last.is_a?(Hash) ? args.pop : {}
+      destination = args.first || source.sub(/#{TEMPLATE_EXTNAME}$/, "")
+
+      source  = File.expand_path(find_in_source_paths(source.to_s))
+      context = config.delete(:context) || instance_eval("binding")
+
+      create_file destination, nil, config do
+        capturable_erb = CapturableERB.new(::File.binread(source), trim_mode: "-", eoutvar: "@output_buffer")
+        content = capturable_erb.tap do |erb|
+          erb.filename = source
+        end.result(context)
+        content = yield(content) if block
+        content
+      end
+    end
+
+    # Changes the mode of the given file or directory.
+    #
+    # ==== Parameters
+    # mode<Integer>:: the file mode
+    # path<String>:: the name of the file to change mode
+    # config<Hash>:: give :verbose => false to not log the status.
+    #
+    # ==== Example
+    #
+    #   chmod "script/server", 0755
+    #
+    def chmod(path, mode, config = {})
+      return unless behavior == :invoke
+      path = File.expand_path(path, destination_root)
+      say_status :chmod, relative_to_original_destination_root(path), config.fetch(:verbose, true)
+      unless options[:pretend]
+        require "fileutils"
+        FileUtils.chmod_R(mode, path)
+      end
+    end
+
+    # Prepend text to a file. Since it depends on insert_into_file, it's reversible.
+    #
+    # ==== Parameters
+    # path<String>:: path of the file to be changed
+    # data<String>:: the data to prepend to the file, can be also given as a block.
+    # config<Hash>:: give :verbose => false to not log the status.
+    #
+    # ==== Example
+    #
+    #   prepend_to_file 'config/environments/test.rb', 'config.gem "rspec"'
+    #
+    #   prepend_to_file 'config/environments/test.rb' do
+    #     'config.gem "rspec"'
+    #   end
+    #
+    def prepend_to_file(path, *args, &block)
+      config = args.last.is_a?(Hash) ? args.pop : {}
+      config[:after] = /\A/
+      insert_into_file(path, *(args << config), &block)
+    end
+    alias_method :prepend_file, :prepend_to_file
+
+    # Append text to a file. Since it depends on insert_into_file, it's reversible.
+    #
+    # ==== Parameters
+    # path<String>:: path of the file to be changed
+    # data<String>:: the data to append to the file, can be also given as a block.
+    # config<Hash>:: give :verbose => false to not log the status.
+    #
+    # ==== Example
+    #
+    #   append_to_file 'config/environments/test.rb', 'config.gem "rspec"'
+    #
+    #   append_to_file 'config/environments/test.rb' do
+    #     'config.gem "rspec"'
+    #   end
+    #
+    def append_to_file(path, *args, &block)
+      config = args.last.is_a?(Hash) ? args.pop : {}
+      config[:before] = /\z/
+      insert_into_file(path, *(args << config), &block)
+    end
+    alias_method :append_file, :append_to_file
+
+    # Injects text right after the class definition. Since it depends on
+    # insert_into_file, it's reversible.
+    #
+    # ==== Parameters
+    # path<String>:: path of the file to be changed
+    # klass<String|Class>:: the class to be manipulated
+    # data<String>:: the data to append to the class, can be also given as a block.
+    # config<Hash>:: give :verbose => false to not log the status.
+    #
+    # ==== Examples
+    #
+    #   inject_into_class "app/controllers/application_controller.rb", "ApplicationController", "  filter_parameter :password\n"
+    #
+    #   inject_into_class "app/controllers/application_controller.rb", "ApplicationController" do
+    #     "  filter_parameter :password\n"
+    #   end
+    #
+    def inject_into_class(path, klass, *args, &block)
+      config = args.last.is_a?(Hash) ? args.pop : {}
+      config[:after] = /class #{klass}\n|class #{klass} .*\n/
+      insert_into_file(path, *(args << config), &block)
+    end
+
+    # Injects text right after the module definition. Since it depends on
+    # insert_into_file, it's reversible.
+    #
+    # ==== Parameters
+    # path<String>:: path of the file to be changed
+    # module_name<String|Class>:: the module to be manipulated
+    # data<String>:: the data to append to the class, can be also given as a block.
+    # config<Hash>:: give :verbose => false to not log the status.
+    #
+    # ==== Examples
+    #
+    #   inject_into_module "app/helpers/application_helper.rb", "ApplicationHelper", "  def help; 'help'; end\n"
+    #
+    #   inject_into_module "app/helpers/application_helper.rb", "ApplicationHelper" do
+    #     "  def help; 'help'; end\n"
+    #   end
+    #
+    def inject_into_module(path, module_name, *args, &block)
+      config = args.last.is_a?(Hash) ? args.pop : {}
+      config[:after] = /module #{module_name}\n|module #{module_name} .*\n/
+      insert_into_file(path, *(args << config), &block)
+    end
+
+    # Run a regular expression replacement on a file, raising an error if the
+    # contents of the file are not changed.
+    #
+    # ==== Parameters
+    # path<String>:: path of the file to be changed
+    # flag<Regexp|String>:: the regexp or string to be replaced
+    # replacement<String>:: the replacement, can be also given as a block
+    # config<Hash>:: give :verbose => false to not log the status, and
+    #                :force => true, to force the replacement regardless of runner behavior.
+    #
+    # ==== Example
+    #
+    #   gsub_file! 'app/controllers/application_controller.rb', /#\s*(filter_parameter_logging :password)/, '\1'
+    #
+    #   gsub_file! 'README', /rake/, :green do |match|
+    #     match << " no more. Use thor!"
+    #   end
+    #
+    def gsub_file!(path, flag, *args, &block)
+      config = args.last.is_a?(Hash) ? args.pop : {}
+
+      return unless behavior == :invoke || config.fetch(:force, false)
+
+      path = File.expand_path(path, destination_root)
+      say_status :gsub, relative_to_original_destination_root(path), config.fetch(:verbose, true)
+
+      actually_gsub_file(path, flag, args, true, &block) unless options[:pretend]
+    end
+
+    # Run a regular expression replacement on a file.
+    #
+    # ==== Parameters
+    # path<String>:: path of the file to be changed
+    # flag<Regexp|String>:: the regexp or string to be replaced
+    # replacement<String>:: the replacement, can be also given as a block
+    # config<Hash>:: give :verbose => false to not log the status, and
+    #                :force => true, to force the replacement regardless of runner behavior.
+    #
+    # ==== Example
+    #
+    #   gsub_file 'app/controllers/application_controller.rb', /#\s*(filter_parameter_logging :password)/, '\1'
+    #
+    #   gsub_file 'README', /rake/, :green do |match|
+    #     match << " no more. Use thor!"
+    #   end
+    #
+    def gsub_file(path, flag, *args, &block)
+      config = args.last.is_a?(Hash) ? args.pop : {}
+
+      return unless behavior == :invoke || config.fetch(:force, false)
+
+      path = File.expand_path(path, destination_root)
+      say_status :gsub, relative_to_original_destination_root(path), config.fetch(:verbose, true)
+
+      actually_gsub_file(path, flag, args, false, &block) unless options[:pretend]
+    end
+
+    # Uncomment all lines matching a given regex. Preserves indentation before
+    # the comment hash and removes the hash and any immediate following space.
+    #
+    # ==== Parameters
+    # path<String>:: path of the file to be changed
+    # flag<Regexp|String>:: the regexp or string used to decide which lines to uncomment
+    # config<Hash>:: give :verbose => false to not log the status.
+    #
+    # ==== Example
+    #
+    #   uncomment_lines 'config/initializers/session_store.rb', /active_record/
+    #
+    def uncomment_lines(path, flag, *args)
+      flag = flag.respond_to?(:source) ? flag.source : flag
+
+      gsub_file(path, /^(\s*)#[[:blank:]]?(.*#{flag})/, '\1\2', *args)
+    end
+
+    # Comment all lines matching a given regex.  It will leave the space
+    # which existed before the beginning of the line in tact and will insert
+    # a single space after the comment hash.
+    #
+    # ==== Parameters
+    # path<String>:: path of the file to be changed
+    # flag<Regexp|String>:: the regexp or string used to decide which lines to comment
+    # config<Hash>:: give :verbose => false to not log the status.
+    #
+    # ==== Example
+    #
+    #   comment_lines 'config/initializers/session_store.rb', /cookie_store/
+    #
+    def comment_lines(path, flag, *args)
+      flag = flag.respond_to?(:source) ? flag.source : flag
+
+      gsub_file(path, /^(\s*)([^#\n]*#{flag})/, '\1# \2', *args)
+    end
+
+    # Removes a file at the given location.
+    #
+    # ==== Parameters
+    # path<String>:: path of the file to be changed
+    # config<Hash>:: give :verbose => false to not log the status.
+    #
+    # ==== Example
+    #
+    #   remove_file 'README'
+    #   remove_file 'app/controllers/application_controller.rb'
+    #
+    def remove_file(path, config = {})
+      return unless behavior == :invoke
+      path = File.expand_path(path, destination_root)
+
+      say_status :remove, relative_to_original_destination_root(path), config.fetch(:verbose, true)
+      if !options[:pretend] && (File.exist?(path) || File.symlink?(path))
+        require "fileutils"
+        ::FileUtils.rm_rf(path)
+      end
+    end
+    alias_method :remove_dir, :remove_file
+
+    attr_accessor :output_buffer
+    private :output_buffer, :output_buffer=
+
+  private
+
+    def concat(string)
+      @output_buffer.concat(string)
+    end
+
+    def capture(*args)
+      with_output_buffer { yield(*args) }
+    end
+
+    def with_output_buffer(buf = "".dup) #:nodoc:
+      raise ArgumentError, "Buffer cannot be a frozen object" if buf.frozen?
+      old_buffer = output_buffer
+      self.output_buffer = buf
+      yield
+      output_buffer
+    ensure
+      self.output_buffer = old_buffer
+    end
+
+    def actually_gsub_file(path, flag, args, error_on_no_change, &block)
+      content = File.binread(path)
+      success = content.gsub!(flag, *args, &block)
+
+      if success.nil? && error_on_no_change
+        raise Bundler::Thor::Error, "The content of #{path} did not change"
+      end
+
+      File.open(path, "wb") { |file| file.write(content) }
+    end
+
+    # Bundler::Thor::Actions#capture depends on what kind of buffer is used in ERB.
+    # Thus CapturableERB fixes ERB to use String buffer.
+    class CapturableERB < ERB
+      def set_eoutvar(compiler, eoutvar = "_erbout")
+        compiler.put_cmd = "#{eoutvar}.concat"
+        compiler.insert_cmd = "#{eoutvar}.concat"
+        compiler.pre_cmd = ["#{eoutvar} = ''.dup"]
+        compiler.post_cmd = [eoutvar]
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/actions/inject_into_file.rb b/lib/bundler/vendor/thor/lib/thor/actions/inject_into_file.rb
new file mode 100644
index 0000000000..70526e615f
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/actions/inject_into_file.rb
@@ -0,0 +1,130 @@
+require_relative "empty_directory"
+
+class Bundler::Thor
+  module Actions
+    # Injects the given content into a file. Different from gsub_file, this
+    # method is reversible.
+    #
+    # ==== Parameters
+    # destination<String>:: Relative path to the destination root
+    # data<String>:: Data to add to the file. Can be given as a block.
+    # config<Hash>:: give :verbose => false to not log the status and the flag
+    #                for injection (:after or :before) or :force => true for
+    #                insert two or more times the same content.
+    #
+    # ==== Examples
+    #
+    #   insert_into_file "config/environment.rb", "config.gem :thor", :after => "Rails::Initializer.run do |config|\n"
+    #
+    #   insert_into_file "config/environment.rb", :after => "Rails::Initializer.run do |config|\n" do
+    #     gems = ask "Which gems would you like to add?"
+    #     gems.split(" ").map{ |gem| "  config.gem :#{gem}" }.join("\n")
+    #   end
+    #
+    WARNINGS = {unchanged_no_flag: "File unchanged! Either the supplied flag value not found or the content has already been inserted!"}
+
+    def insert_into_file(destination, *args, &block)
+      data = block_given? ? block : args.shift
+
+      config = args.shift || {}
+      config[:after] = /\z/ unless config.key?(:before) || config.key?(:after)
+
+      action InjectIntoFile.new(self, destination, data, config)
+    end
+    alias_method :inject_into_file, :insert_into_file
+
+    class InjectIntoFile < EmptyDirectory #:nodoc:
+      attr_reader :replacement, :flag, :behavior
+
+      def initialize(base, destination, data, config)
+        super(base, destination, {verbose: true}.merge(config))
+
+        @behavior, @flag = if @config.key?(:after)
+          [:after, @config.delete(:after)]
+        else
+          [:before, @config.delete(:before)]
+        end
+
+        @replacement = data.is_a?(Proc) ? data.call : data
+        @flag = Regexp.escape(@flag) unless @flag.is_a?(Regexp)
+      end
+
+      def invoke!
+        content = if @behavior == :after
+          '\0' + replacement
+        else
+          replacement + '\0'
+        end
+
+        if exists?
+          if replace!(/#{flag}/, content, config[:force])
+            say_status(:invoke)
+          elsif replacement_present?
+            say_status(:unchanged, color: :blue)
+          else
+            say_status(:unchanged, warning: WARNINGS[:unchanged_no_flag], color: :red)
+          end
+        else
+          unless pretend?
+            raise Bundler::Thor::Error, "The file #{ destination } does not appear to exist"
+          end
+        end
+      end
+
+      def revoke!
+        say_status :revoke
+
+        regexp = if @behavior == :after
+          content = '\1\2'
+          /(#{flag})(.*)(#{Regexp.escape(replacement)})/m
+        else
+          content = '\2\3'
+          /(#{Regexp.escape(replacement)})(.*)(#{flag})/m
+        end
+
+        replace!(regexp, content, true)
+      end
+
+    protected
+
+      def say_status(behavior, warning: nil, color: nil)
+        status = if behavior == :invoke
+          if flag == /\A/
+            :prepend
+          elsif flag == /\z/
+            :append
+          else
+            :insert
+          end
+        elsif warning
+          warning
+        elsif behavior == :unchanged
+          :unchanged
+        else
+          :subtract
+        end
+
+        super(status, (color || config[:verbose]))
+      end
+
+      def content
+        @content ||= File.read(destination)
+      end
+
+      def replacement_present?
+        content.include?(replacement)
+      end
+
+      # Adds the content to the file.
+      #
+      def replace!(regexp, string, force)
+        if force || !replacement_present?
+          success = content.gsub!(regexp, string)
+
+          File.open(destination, "wb") { |file| file.write(content) } unless pretend?
+          success
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/base.rb b/lib/bundler/vendor/thor/lib/thor/base.rb
new file mode 100644
index 0000000000..b156899c1e
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/base.rb
@@ -0,0 +1,825 @@
+require_relative "command"
+require_relative "core_ext/hash_with_indifferent_access"
+require_relative "error"
+require_relative "invocation"
+require_relative "nested_context"
+require_relative "parser"
+require_relative "shell"
+require_relative "line_editor"
+require_relative "util"
+
+class Bundler::Thor
+  autoload :Actions,    File.expand_path("actions", __dir__)
+  autoload :RakeCompat, File.expand_path("rake_compat", __dir__)
+  autoload :Group,      File.expand_path("group", __dir__)
+
+  # Shortcuts for help.
+  HELP_MAPPINGS       = %w(-h -? --help -D)
+
+  # Bundler::Thor methods that should not be overwritten by the user.
+  THOR_RESERVED_WORDS = %w(invoke shell options behavior root destination_root relative_root
+                           action add_file create_file in_root inside run run_ruby_script)
+
+  TEMPLATE_EXTNAME = ".tt"
+
+  class << self
+    def deprecation_warning(message) #:nodoc:
+      unless ENV["THOR_SILENCE_DEPRECATION"]
+        warn "Deprecation warning: #{message}\n" +
+          "You can silence deprecations warning by setting the environment variable THOR_SILENCE_DEPRECATION."
+      end
+    end
+  end
+
+  module Base
+    attr_accessor :options, :parent_options, :args
+
+    # It receives arguments in an Array and two hashes, one for options and
+    # other for configuration.
+    #
+    # Notice that it does not check if all required arguments were supplied.
+    # It should be done by the parser.
+    #
+    # ==== Parameters
+    # args<Array[Object]>:: An array of objects. The objects are applied to their
+    #                       respective accessors declared with <tt>argument</tt>.
+    #
+    # options<Hash>:: An options hash that will be available as self.options.
+    #                 The hash given is converted to a hash with indifferent
+    #                 access, magic predicates (options.skip?) and then frozen.
+    #
+    # config<Hash>:: Configuration for this Bundler::Thor class.
+    #
+    def initialize(args = [], local_options = {}, config = {})
+      parse_options = self.class.class_options
+
+      # The start method splits inbound arguments at the first argument
+      # that looks like an option (starts with - or --). It then calls
+      # new, passing in the two halves of the arguments Array as the
+      # first two parameters.
+
+      command_options = config.delete(:command_options) # hook for start
+      parse_options = parse_options.merge(command_options) if command_options
+
+      if local_options.is_a?(Array)
+        array_options = local_options
+        hash_options = {}
+      else
+        # Handle the case where the class was explicitly instantiated
+        # with pre-parsed options.
+        array_options = []
+        hash_options = local_options
+      end
+
+      # Let Bundler::Thor::Options parse the options first, so it can remove
+      # declared options from the array. This will leave us with
+      # a list of arguments that weren't declared.
+      current_command = config[:current_command]
+      stop_on_unknown = self.class.stop_on_unknown_option? current_command
+
+      # Give a relation of options.
+      # After parsing, Bundler::Thor::Options check whether right relations are kept
+      relations = if current_command.nil?
+        {exclusive_option_names: [], at_least_one_option_names: []}
+      else
+        current_command.options_relation
+      end
+
+      self.class.class_exclusive_option_names.map { |n| relations[:exclusive_option_names] << n }
+      self.class.class_at_least_one_option_names.map { |n| relations[:at_least_one_option_names] << n }
+
+      disable_required_check = self.class.disable_required_check? current_command
+
+      opts = Bundler::Thor::Options.new(parse_options, hash_options, stop_on_unknown, disable_required_check, relations)
+
+      self.options = opts.parse(array_options)
+      self.options = config[:class_options].merge(options) if config[:class_options]
+
+      # If unknown options are disallowed, make sure that none of the
+      # remaining arguments looks like an option.
+      opts.check_unknown! if self.class.check_unknown_options?(config)
+
+      # Add the remaining arguments from the options parser to the
+      # arguments passed in to initialize. Then remove any positional
+      # arguments declared using #argument (this is primarily used
+      # by Bundler::Thor::Group). Tis will leave us with the remaining
+      # positional arguments.
+      to_parse  = args
+      to_parse += opts.remaining unless self.class.strict_args_position?(config)
+
+      thor_args = Bundler::Thor::Arguments.new(self.class.arguments)
+      thor_args.parse(to_parse).each { |k, v| __send__("#{k}=", v) }
+      @args = thor_args.remaining
+    end
+
+    class << self
+      def included(base) #:nodoc:
+        super(base)
+        base.extend ClassMethods
+        base.send :include, Invocation
+        base.send :include, Shell
+      end
+
+      # Returns the classes that inherits from Bundler::Thor or Bundler::Thor::Group.
+      #
+      # ==== Returns
+      # Array[Class]
+      #
+      def subclasses
+        @subclasses ||= []
+      end
+
+      # Returns the files where the subclasses are kept.
+      #
+      # ==== Returns
+      # Hash[path<String> => Class]
+      #
+      def subclass_files
+        @subclass_files ||= Hash.new { |h, k| h[k] = [] }
+      end
+
+      # Whenever a class inherits from Bundler::Thor or Bundler::Thor::Group, we should track the
+      # class and the file on Bundler::Thor::Base. This is the method responsible for it.
+      #
+      def register_klass_file(klass) #:nodoc:
+        file = caller[1].match(/(.*):\d+/)[1]
+        Bundler::Thor::Base.subclasses << klass unless Bundler::Thor::Base.subclasses.include?(klass)
+
+        file_subclasses = Bundler::Thor::Base.subclass_files[File.expand_path(file)]
+        file_subclasses << klass unless file_subclasses.include?(klass)
+      end
+    end
+
+    module ClassMethods
+      def attr_reader(*) #:nodoc:
+        no_commands { super }
+      end
+
+      def attr_writer(*) #:nodoc:
+        no_commands { super }
+      end
+
+      def attr_accessor(*) #:nodoc:
+        no_commands { super }
+      end
+
+      # If you want to raise an error for unknown options, call check_unknown_options!
+      # This is disabled by default to allow dynamic invocations.
+      def check_unknown_options!
+        @check_unknown_options = true
+      end
+
+      def check_unknown_options #:nodoc:
+        @check_unknown_options ||= from_superclass(:check_unknown_options, false)
+      end
+
+      def check_unknown_options?(config) #:nodoc:
+        !!check_unknown_options
+      end
+
+      # If you want to raise an error when the default value of an option does not match
+      # the type call check_default_type!
+      # This will be the default; for compatibility a deprecation warning is issued if necessary.
+      def check_default_type!
+        @check_default_type = true
+      end
+
+      # If you want to use defaults that don't match the type of an option,
+      # either specify `check_default_type: false` or call `allow_incompatible_default_type!`
+      def allow_incompatible_default_type!
+        @check_default_type = false
+      end
+
+      def check_default_type #:nodoc:
+        @check_default_type = from_superclass(:check_default_type, nil) unless defined?(@check_default_type)
+        @check_default_type
+      end
+
+      # If true, option parsing is suspended as soon as an unknown option or a
+      # regular argument is encountered.  All remaining arguments are passed to
+      # the command as regular arguments.
+      def stop_on_unknown_option?(command_name) #:nodoc:
+        false
+      end
+
+      # If true, option set will not suspend the execution of the command when
+      # a required option is not provided.
+      def disable_required_check?(command_name) #:nodoc:
+        false
+      end
+
+      # If you want only strict string args (useful when cascading thor classes),
+      # call strict_args_position! This is disabled by default to allow dynamic
+      # invocations.
+      def strict_args_position!
+        @strict_args_position = true
+      end
+
+      def strict_args_position #:nodoc:
+        @strict_args_position ||= from_superclass(:strict_args_position, false)
+      end
+
+      def strict_args_position?(config) #:nodoc:
+        !!strict_args_position
+      end
+
+      # Adds an argument to the class and creates an attr_accessor for it.
+      #
+      # Arguments are different from options in several aspects. The first one
+      # is how they are parsed from the command line, arguments are retrieved
+      # from position:
+      #
+      #   thor command NAME
+      #
+      # Instead of:
+      #
+      #   thor command --name=NAME
+      #
+      # Besides, arguments are used inside your code as an accessor (self.argument),
+      # while options are all kept in a hash (self.options).
+      #
+      # Finally, arguments cannot have type :default or :boolean but can be
+      # optional (supplying :optional => :true or :required => false), although
+      # you cannot have a required argument after a non-required argument. If you
+      # try it, an error is raised.
+      #
+      # ==== Parameters
+      # name<Symbol>:: The name of the argument.
+      # options<Hash>:: Described below.
+      #
+      # ==== Options
+      # :desc     - Description for the argument.
+      # :required - If the argument is required or not.
+      # :optional - If the argument is optional or not.
+      # :type     - The type of the argument, can be :string, :hash, :array, :numeric.
+      # :default  - Default value for this argument. It cannot be required and have default values.
+      # :banner   - String to show on usage notes.
+      #
+      # ==== Errors
+      # ArgumentError:: Raised if you supply a required argument after a non required one.
+      #
+      def argument(name, options = {})
+        is_thor_reserved_word?(name, :argument)
+        no_commands { attr_accessor name }
+
+        required = if options.key?(:optional)
+          !options[:optional]
+        elsif options.key?(:required)
+          options[:required]
+        else
+          options[:default].nil?
+        end
+
+        remove_argument name
+
+        if required
+          arguments.each do |argument|
+            next if argument.required?
+            raise ArgumentError, "You cannot have #{name.to_s.inspect} as required argument after " \
+                                "the non-required argument #{argument.human_name.inspect}."
+          end
+        end
+
+        options[:required] = required
+
+        arguments << Bundler::Thor::Argument.new(name, options)
+      end
+
+      # Returns this class arguments, looking up in the ancestors chain.
+      #
+      # ==== Returns
+      # Array[Bundler::Thor::Argument]
+      #
+      def arguments
+        @arguments ||= from_superclass(:arguments, [])
+      end
+
+      # Adds a bunch of options to the set of class options.
+      #
+      #   class_options :foo => false, :bar => :required, :baz => :string
+      #
+      # If you prefer more detailed declaration, check class_option.
+      #
+      # ==== Parameters
+      # Hash[Symbol => Object]
+      #
+      def class_options(options = nil)
+        @class_options ||= from_superclass(:class_options, {})
+        build_options(options, @class_options) if options
+        @class_options
+      end
+
+      # Adds an option to the set of class options
+      #
+      # ==== Parameters
+      # name<Symbol>:: The name of the argument.
+      # options<Hash>:: Described below.
+      #
+      # ==== Options
+      # :desc::     -- Description for the argument.
+      # :required:: -- If the argument is required or not.
+      # :default::  -- Default value for this argument.
+      # :group::    -- The group for this options. Use by class options to output options in different levels.
+      # :aliases::  -- Aliases for this option. <b>Note:</b> Bundler::Thor follows a convention of one-dash-one-letter options. Thus aliases like "-something" wouldn't be parsed; use either "\--something" or "-s" instead.
+      # :type::     -- The type of the argument, can be :string, :hash, :array, :numeric or :boolean.
+      # :banner::   -- String to show on usage notes.
+      # :hide::     -- If you want to hide this option from the help.
+      #
+      def class_option(name, options = {})
+        unless [ Symbol, String ].any? { |klass| name.is_a?(klass) }
+          raise ArgumentError, "Expected a Symbol or String, got #{name.inspect}"
+        end
+        build_option(name, options, class_options)
+      end
+
+      # Adds and declares option group for exclusive options in the
+      # block and arguments. You can declare options as the outside of the block.
+      #
+      # ==== Parameters
+      # Array[Bundler::Thor::Option.name]
+      #
+      # ==== Examples
+      #
+      #   class_exclusive do
+      #     class_option :one
+      #     class_option :two
+      #    end
+      #
+      # Or
+      #
+      #   class_option :one
+      #   class_option :two
+      #   class_exclusive :one, :two
+      #
+      # If you give "--one" and "--two" at the same time ExclusiveArgumentsError
+      # will be raised.
+      #
+      def class_exclusive(*args, &block)
+        register_options_relation_for(:class_options,
+                                      :class_exclusive_option_names, *args, &block)
+      end
+
+      # Adds and declares option group for required at least one of options in the
+      # block and arguments. You can declare options as the outside of the block.
+      #
+      # ==== Examples
+      #
+      #   class_at_least_one do
+      #     class_option :one
+      #     class_option :two
+      #    end
+      #
+      # Or
+      #
+      #   class_option :one
+      #   class_option :two
+      #   class_at_least_one :one, :two
+      #
+      # If you do not give "--one" and "--two" AtLeastOneRequiredArgumentError
+      # will be raised.
+      #
+      # You can use class_at_least_one and class_exclusive at the same time.
+      #
+      #    class_exclusive do
+      #      class_at_least_one do
+      #        class_option :one
+      #        class_option :two
+      #      end
+      #    end
+      #
+      # Then it is required either only one of "--one" or "--two".
+      #
+      def class_at_least_one(*args, &block)
+        register_options_relation_for(:class_options,
+                                      :class_at_least_one_option_names, *args, &block)
+      end
+
+      # Returns this class exclusive options array set, looking up in the ancestors chain.
+      #
+      # ==== Returns
+      # Array[Array[Bundler::Thor::Option.name]]
+      #
+      def class_exclusive_option_names
+        @class_exclusive_option_names ||= from_superclass(:class_exclusive_option_names, [])
+      end
+
+      # Returns this class at least one of required options array set, looking up in the ancestors chain.
+      #
+      # ==== Returns
+      # Array[Array[Bundler::Thor::Option.name]]
+      #
+      def class_at_least_one_option_names
+        @class_at_least_one_option_names ||= from_superclass(:class_at_least_one_option_names, [])
+      end
+
+      # Removes a previous defined argument. If :undefine is given, undefine
+      # accessors as well.
+      #
+      # ==== Parameters
+      # names<Array>:: Arguments to be removed
+      #
+      # ==== Examples
+      #
+      #   remove_argument :foo
+      #   remove_argument :foo, :bar, :baz, :undefine => true
+      #
+      def remove_argument(*names)
+        options = names.last.is_a?(Hash) ? names.pop : {}
+
+        names.each do |name|
+          arguments.delete_if { |a| a.name == name.to_s }
+          undef_method name, "#{name}=" if options[:undefine]
+        end
+      end
+
+      # Removes a previous defined class option.
+      #
+      # ==== Parameters
+      # names<Array>:: Class options to be removed
+      #
+      # ==== Examples
+      #
+      #   remove_class_option :foo
+      #   remove_class_option :foo, :bar, :baz
+      #
+      def remove_class_option(*names)
+        names.each do |name|
+          class_options.delete(name)
+        end
+      end
+
+      # Defines the group. This is used when thor list is invoked so you can specify
+      # that only commands from a pre-defined group will be shown. Defaults to standard.
+      #
+      # ==== Parameters
+      # name<String|Symbol>
+      #
+      def group(name = nil)
+        if name
+          @group = name.to_s
+        else
+          @group ||= from_superclass(:group, "standard")
+        end
+      end
+
+      # Returns the commands for this Bundler::Thor class.
+      #
+      # ==== Returns
+      # Hash:: An ordered hash with commands names as keys and Bundler::Thor::Command
+      #        objects as values.
+      #
+      def commands
+        @commands ||= Hash.new
+      end
+      alias_method :tasks, :commands
+
+      # Returns the commands for this Bundler::Thor class and all subclasses.
+      #
+      # ==== Returns
+      # Hash:: An ordered hash with commands names as keys and Bundler::Thor::Command
+      #        objects as values.
+      #
+      def all_commands
+        @all_commands ||= from_superclass(:all_commands, Hash.new)
+        @all_commands.merge!(commands)
+      end
+      alias_method :all_tasks, :all_commands
+
+      # Removes a given command from this Bundler::Thor class. This is usually done if you
+      # are inheriting from another class and don't want it to be available
+      # anymore.
+      #
+      # By default it only remove the mapping to the command. But you can supply
+      # :undefine => true to undefine the method from the class as well.
+      #
+      # ==== Parameters
+      # name<Symbol|String>:: The name of the command to be removed
+      # options<Hash>:: You can give :undefine => true if you want commands the method
+      #                 to be undefined from the class as well.
+      #
+      def remove_command(*names)
+        options = names.last.is_a?(Hash) ? names.pop : {}
+
+        names.each do |name|
+          commands.delete(name.to_s)
+          all_commands.delete(name.to_s)
+          undef_method name if options[:undefine]
+        end
+      end
+      alias_method :remove_task, :remove_command
+
+      # All methods defined inside the given block are not added as commands.
+      #
+      # So you can do:
+      #
+      #   class MyScript < Bundler::Thor
+      #     no_commands do
+      #       def this_is_not_a_command
+      #       end
+      #     end
+      #   end
+      #
+      # You can also add the method and remove it from the command list:
+      #
+      #   class MyScript < Bundler::Thor
+      #     def this_is_not_a_command
+      #     end
+      #     remove_command :this_is_not_a_command
+      #   end
+      #
+      def no_commands(&block)
+        no_commands_context.enter(&block)
+      end
+
+      alias_method :no_tasks, :no_commands
+
+      def no_commands_context
+        @no_commands_context ||= NestedContext.new
+      end
+
+      def no_commands?
+        no_commands_context.entered?
+      end
+
+      # Sets the namespace for the Bundler::Thor or Bundler::Thor::Group class. By default the
+      # namespace is retrieved from the class name. If your Bundler::Thor class is named
+      # Scripts::MyScript, the help method, for example, will be called as:
+      #
+      #   thor scripts:my_script -h
+      #
+      # If you change the namespace:
+      #
+      #   namespace :my_scripts
+      #
+      # You change how your commands are invoked:
+      #
+      #   thor my_scripts -h
+      #
+      # Finally, if you change your namespace to default:
+      #
+      #   namespace :default
+      #
+      # Your commands can be invoked with a shortcut. Instead of:
+      #
+      #   thor :my_command
+      #
+      def namespace(name = nil)
+        if name
+          @namespace = name.to_s
+        else
+          @namespace ||= Bundler::Thor::Util.namespace_from_thor_class(self)
+        end
+      end
+
+      # Parses the command and options from the given args, instantiate the class
+      # and invoke the command. This method is used when the arguments must be parsed
+      # from an array. If you are inside Ruby and want to use a Bundler::Thor class, you
+      # can simply initialize it:
+      #
+      #   script = MyScript.new(args, options, config)
+      #   script.invoke(:command, first_arg, second_arg, third_arg)
+      #
+      def start(given_args = ARGV, config = {})
+        config[:shell] ||= Bundler::Thor::Base.shell.new
+        dispatch(nil, given_args.dup, nil, config)
+      rescue Bundler::Thor::Error => e
+        config[:debug] || ENV["THOR_DEBUG"] == "1" ? (raise e) : config[:shell].error(e.message)
+        exit(false) if exit_on_failure?
+      rescue Errno::EPIPE
+        # This happens if a thor command is piped to something like `head`,
+        # which closes the pipe when it's done reading. This will also
+        # mean that if the pipe is closed, further unnecessary
+        # computation will not occur.
+        exit(true)
+      end
+
+      # Allows to use private methods from parent in child classes as commands.
+      #
+      # ==== Parameters
+      #   names<Array>:: Method names to be used as commands
+      #
+      # ==== Examples
+      #
+      #   public_command :foo
+      #   public_command :foo, :bar, :baz
+      #
+      def public_command(*names)
+        names.each do |name|
+          class_eval "def #{name}(*); super end", __FILE__, __LINE__
+        end
+      end
+      alias_method :public_task, :public_command
+
+      def handle_no_command_error(command, has_namespace = $thor_runner) #:nodoc:
+        raise UndefinedCommandError.new(command, all_commands.keys, (namespace if has_namespace))
+      end
+      alias_method :handle_no_task_error, :handle_no_command_error
+
+      def handle_argument_error(command, error, args, arity) #:nodoc:
+        name = [command.ancestor_name, command.name].compact.join(" ")
+        msg = "ERROR: \"#{basename} #{name}\" was called with ".dup
+        msg << "no arguments"               if     args.empty?
+        msg << "arguments " << args.inspect unless args.empty?
+        msg << "\nUsage: \"#{banner(command).split("\n").join("\"\n       \"")}\""
+        raise InvocationError, msg
+      end
+
+      # A flag that makes the process exit with status 1 if any error happens.
+      def exit_on_failure?
+        Bundler::Thor.deprecation_warning "Bundler::Thor exit with status 0 on errors. To keep this behavior, you must define `exit_on_failure?` in `#{self.name}`"
+        false
+      end
+
+    protected
+
+      # Prints the class options per group. If an option does not belong to
+      # any group, it's printed as Class option.
+      #
+      def class_options_help(shell, groups = {}) #:nodoc:
+        # Group options by group
+        class_options.each do |_, value|
+          groups[value.group] ||= []
+          groups[value.group] << value
+        end
+
+        # Deal with default group
+        global_options = groups.delete(nil) || []
+        print_options(shell, global_options)
+
+        # Print all others
+        groups.each do |group_name, options|
+          print_options(shell, options, group_name)
+        end
+      end
+
+      # Receives a set of options and print them.
+      def print_options(shell, options, group_name = nil)
+        return if options.empty?
+
+        list = []
+        padding = options.map { |o| o.aliases_for_usage.size }.max.to_i
+        options.each do |option|
+          next if option.hide
+          item = [option.usage(padding)]
+          item.push(option.description ? "# #{option.description}" : "")
+
+          list << item
+          list << ["", "# Default: #{option.print_default}"] if option.show_default?
+          list << ["", "# Possible values: #{option.enum_to_s}"] if option.enum
+        end
+
+        shell.say(group_name ? "#{group_name} options:" : "Options:")
+        shell.print_table(list, indent: 2)
+        shell.say ""
+      end
+
+      # Raises an error if the word given is a Bundler::Thor reserved word.
+      def is_thor_reserved_word?(word, type) #:nodoc:
+        return false unless THOR_RESERVED_WORDS.include?(word.to_s)
+        raise "#{word.inspect} is a Bundler::Thor reserved word and cannot be defined as #{type}"
+      end
+
+      # Build an option and adds it to the given scope.
+      #
+      # ==== Parameters
+      # name<Symbol>:: The name of the argument.
+      # options<Hash>:: Described in both class_option and method_option.
+      # scope<Hash>:: Options hash that is being built up
+      def build_option(name, options, scope) #:nodoc:
+        scope[name] = Bundler::Thor::Option.new(name, {check_default_type: check_default_type}.merge!(options))
+      end
+
+      # Receives a hash of options, parse them and add to the scope. This is a
+      # fast way to set a bunch of options:
+      #
+      #   build_options :foo => true, :bar => :required, :baz => :string
+      #
+      # ==== Parameters
+      # Hash[Symbol => Object]
+      def build_options(options, scope) #:nodoc:
+        options.each do |key, value|
+          scope[key] = Bundler::Thor::Option.parse(key, value)
+        end
+      end
+
+      # Finds a command with the given name. If the command belongs to the current
+      # class, just return it, otherwise dup it and add the fresh copy to the
+      # current command hash.
+      def find_and_refresh_command(name) #:nodoc:
+        if commands[name.to_s]
+          commands[name.to_s]
+        elsif command = all_commands[name.to_s] # rubocop:disable Lint/AssignmentInCondition
+          commands[name.to_s] = command.clone
+        else
+          raise ArgumentError, "You supplied :for => #{name.inspect}, but the command #{name.inspect} could not be found."
+        end
+      end
+      alias_method :find_and_refresh_task, :find_and_refresh_command
+
+      # Every time someone inherits from a Bundler::Thor class, register the klass
+      # and file into baseclass.
+      def inherited(klass)
+        super(klass)
+        Bundler::Thor::Base.register_klass_file(klass)
+        klass.instance_variable_set(:@no_commands, 0)
+      end
+
+      # Fire this callback whenever a method is added. Added methods are
+      # tracked as commands by invoking the create_command method.
+      def method_added(meth)
+        super(meth)
+        meth = meth.to_s
+
+        if meth == "initialize"
+          initialize_added
+          return
+        end
+
+        # Return if it's not a public instance method
+        return unless public_method_defined?(meth.to_sym)
+
+        return if no_commands? || !create_command(meth)
+
+        is_thor_reserved_word?(meth, :command)
+        Bundler::Thor::Base.register_klass_file(self)
+      end
+
+      # Retrieves a value from superclass. If it reaches the baseclass,
+      # returns default.
+      def from_superclass(method, default = nil)
+        if self == baseclass || !superclass.respond_to?(method, true)
+          default
+        else
+          value = superclass.send(method)
+
+          # Ruby implements `dup` on Object, but raises a `TypeError`
+          # if the method is called on immediates. As a result, we
+          # don't have a good way to check whether dup will succeed
+          # without calling it and rescuing the TypeError.
+          begin
+            value.dup
+          rescue TypeError
+            value
+          end
+
+        end
+      end
+
+      #
+      # The basename of the program invoking the thor class.
+      #
+      def basename
+        File.basename($PROGRAM_NAME).split(" ").first
+      end
+
+      # SIGNATURE: Sets the baseclass. This is where the superclass lookup
+      # finishes.
+      def baseclass #:nodoc:
+      end
+
+      # SIGNATURE: Creates a new command if valid_command? is true. This method is
+      # called when a new method is added to the class.
+      def create_command(meth) #:nodoc:
+      end
+      alias_method :create_task, :create_command
+
+      # SIGNATURE: Defines behavior when the initialize method is added to the
+      # class.
+      def initialize_added #:nodoc:
+      end
+
+      # SIGNATURE: The hook invoked by start.
+      def dispatch(command, given_args, given_opts, config) #:nodoc:
+        raise NotImplementedError
+      end
+
+      # Register a relation of options for target(method_option/class_option)
+      # by args and block.
+      def register_options_relation_for(target, relation, *args, &block) # :nodoc:
+        opt = args.pop if args.last.is_a? Hash
+        opt ||= {}
+        names = args.map{ |arg| arg.to_s }
+        names += built_option_names(target, opt, &block) if block_given?
+        command_scope_member(relation, opt) << names
+      end
+
+      # Get target(method_options or class_options) options
+      # of before and after by block evaluation.
+      def built_option_names(target, opt = {}, &block) # :nodoc:
+        before = command_scope_member(target, opt).map{ |k,v| v.name }
+        instance_eval(&block)
+        after  = command_scope_member(target, opt).map{ |k,v| v.name }
+        after - before
+      end
+
+      # Get command scope member by name.
+      def command_scope_member(name, options = {}) # :nodoc:
+        if options[:for]
+          find_and_refresh_command(options[:for]).send(name)
+        else
+          send(name)
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/command.rb b/lib/bundler/vendor/thor/lib/thor/command.rb
new file mode 100644
index 0000000000..68c8fffedb
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/command.rb
@@ -0,0 +1,151 @@
+class Bundler::Thor
+  class Command < Struct.new(:name, :description, :long_description, :wrap_long_description, :usage, :options, :options_relation, :ancestor_name)
+    FILE_REGEXP = /^#{Regexp.escape(File.dirname(__FILE__))}/
+
+    def initialize(name, description, long_description, wrap_long_description, usage, options = nil, options_relation = nil)
+      super(name.to_s, description, long_description, wrap_long_description, usage, options || {}, options_relation || {})
+    end
+
+    def initialize_copy(other) #:nodoc:
+      super(other)
+      self.options = other.options.dup if other.options
+      self.options_relation = other.options_relation.dup if other.options_relation
+    end
+
+    def hidden?
+      false
+    end
+
+    # By default, a command invokes a method in the thor class. You can change this
+    # implementation to create custom commands.
+    def run(instance, args = [])
+      arity = nil
+
+      if private_method?(instance)
+        instance.class.handle_no_command_error(name)
+      elsif public_method?(instance)
+        arity = instance.method(name).arity
+        instance.__send__(name, *args)
+      elsif local_method?(instance, :method_missing)
+        instance.__send__(:method_missing, name.to_sym, *args)
+      else
+        instance.class.handle_no_command_error(name)
+      end
+    rescue ArgumentError => e
+      handle_argument_error?(instance, e, caller) ? instance.class.handle_argument_error(self, e, args, arity) : (raise e)
+    rescue NoMethodError => e
+      handle_no_method_error?(instance, e, caller) ? instance.class.handle_no_command_error(name) : (raise e)
+    end
+
+    # Returns the formatted usage by injecting given required arguments
+    # and required options into the given usage.
+    def formatted_usage(klass, namespace = true, subcommand = false)
+      if ancestor_name
+        formatted = "#{ancestor_name} ".dup # add space
+      elsif namespace
+        namespace = klass.namespace
+        formatted = "#{namespace.gsub(/^(default)/, '')}:".dup
+      end
+      formatted ||= "#{klass.namespace.split(':').last} ".dup if subcommand
+
+      formatted ||= "".dup
+
+      Array(usage).map do |specific_usage|
+        formatted_specific_usage = formatted
+
+        formatted_specific_usage += required_arguments_for(klass, specific_usage)
+
+        # Add required options
+        formatted_specific_usage += " #{required_options}"
+
+        # Strip and go!
+        formatted_specific_usage.strip
+      end.join("\n")
+    end
+
+    def method_exclusive_option_names #:nodoc:
+      self.options_relation[:exclusive_option_names] || []
+    end
+
+    def method_at_least_one_option_names #:nodoc:
+      self.options_relation[:at_least_one_option_names] || []
+    end
+
+  protected
+
+    # Add usage with required arguments
+    def required_arguments_for(klass, usage)
+      if klass && !klass.arguments.empty?
+        usage.to_s.gsub(/^#{name}/) do |match|
+          match << " " << klass.arguments.map(&:usage).compact.join(" ")
+        end
+      else
+        usage.to_s
+      end
+    end
+
+    def not_debugging?(instance)
+      !(instance.class.respond_to?(:debugging) && instance.class.debugging)
+    end
+
+    def required_options
+      @required_options ||= options.map { |_, o| o.usage if o.required? }.compact.sort.join(" ")
+    end
+
+    # Given a target, checks if this class name is a public method.
+    def public_method?(instance) #:nodoc:
+      !(instance.public_methods & [name.to_s, name.to_sym]).empty?
+    end
+
+    def private_method?(instance)
+      !(instance.private_methods & [name.to_s, name.to_sym]).empty?
+    end
+
+    def local_method?(instance, name)
+      methods = instance.public_methods(false) + instance.private_methods(false) + instance.protected_methods(false)
+      !(methods & [name.to_s, name.to_sym]).empty?
+    end
+
+    def sans_backtrace(backtrace, caller) #:nodoc:
+      saned = backtrace.reject { |frame| frame =~ FILE_REGEXP || (frame =~ /\.java:/ && RUBY_PLATFORM =~ /java/) || (frame =~ %r{^kernel/} && RUBY_ENGINE =~ /rbx/) }
+      saned - caller
+    end
+
+    def handle_argument_error?(instance, error, caller)
+      not_debugging?(instance) && (error.message =~ /wrong number of arguments/ || error.message =~ /given \d*, expected \d*/) && begin
+        saned = sans_backtrace(error.backtrace, caller)
+        saned.empty? || saned.size == 1
+      end
+    end
+
+    def handle_no_method_error?(instance, error, caller)
+      not_debugging?(instance) &&
+        error.message =~ /^undefined method `#{name}' for #{Regexp.escape(instance.to_s)}$/
+    end
+  end
+  Task = Command
+
+  # A command that is hidden in help messages but still invocable.
+  class HiddenCommand < Command
+    def hidden?
+      true
+    end
+  end
+  HiddenTask = HiddenCommand
+
+  # A dynamic command that handles method missing scenarios.
+  class DynamicCommand < Command
+    def initialize(name, options = nil)
+      super(name.to_s, "A dynamically-generated command", name.to_s, nil, name.to_s, options)
+    end
+
+    def run(instance, args = [])
+      if (instance.methods & [name.to_s, name.to_sym]).empty?
+        super
+      else
+        instance.class.handle_no_command_error(name)
+      end
+    end
+  end
+  DynamicTask = DynamicCommand
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/core_ext/hash_with_indifferent_access.rb b/lib/bundler/vendor/thor/lib/thor/core_ext/hash_with_indifferent_access.rb
new file mode 100644
index 0000000000..b16a98f782
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/core_ext/hash_with_indifferent_access.rb
@@ -0,0 +1,107 @@
+class Bundler::Thor
+  module CoreExt #:nodoc:
+    # A hash with indifferent access and magic predicates.
+    #
+    #   hash = Bundler::Thor::CoreExt::HashWithIndifferentAccess.new 'foo' => 'bar', 'baz' => 'bee', 'force' => true
+    #
+    #   hash[:foo]  #=> 'bar'
+    #   hash['foo'] #=> 'bar'
+    #   hash.foo?   #=> true
+    #
+    class HashWithIndifferentAccess < ::Hash #:nodoc:
+      def initialize(hash = {})
+        super()
+        hash.each do |key, value|
+          self[convert_key(key)] = value
+        end
+      end
+
+      def [](key)
+        super(convert_key(key))
+      end
+
+      def []=(key, value)
+        super(convert_key(key), value)
+      end
+
+      def delete(key)
+        super(convert_key(key))
+      end
+
+      def except(*keys)
+        dup.tap do |hash|
+          keys.each { |key| hash.delete(convert_key(key)) }
+        end
+      end
+
+      def fetch(key, *args)
+        super(convert_key(key), *args)
+      end
+
+      def slice(*keys)
+        super(*keys.map{ |key| convert_key(key) })
+      end
+
+      def key?(key)
+        super(convert_key(key))
+      end
+
+      def values_at(*indices)
+        indices.map { |key| self[convert_key(key)] }
+      end
+
+      def merge(other)
+        dup.merge!(other)
+      end
+
+      def merge!(other)
+        other.each do |key, value|
+          self[convert_key(key)] = value
+        end
+        self
+      end
+
+      def reverse_merge(other)
+        self.class.new(other).merge(self)
+      end
+
+      def reverse_merge!(other_hash)
+        replace(reverse_merge(other_hash))
+      end
+
+      def replace(other_hash)
+        super(other_hash)
+      end
+
+      # Convert to a Hash with String keys.
+      def to_hash
+        Hash.new(default).merge!(self)
+      end
+
+    protected
+
+      def convert_key(key)
+        key.is_a?(Symbol) ? key.to_s : key
+      end
+
+      # Magic predicates. For instance:
+      #
+      #   options.force?                  # => !!options['force']
+      #   options.shebang                 # => "/usr/lib/local/ruby"
+      #   options.test_framework?(:rspec) # => options[:test_framework] == :rspec
+      #
+      def method_missing(method, *args)
+        method = method.to_s
+        if method =~ /^(\w+)\?$/
+          if args.empty?
+            !!self[$1]
+          else
+            self[$1] == args.first
+          end
+        else
+          self[method]
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/error.rb b/lib/bundler/vendor/thor/lib/thor/error.rb
new file mode 100644
index 0000000000..928646e501
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/error.rb
@@ -0,0 +1,106 @@
+class Bundler::Thor
+  Correctable = if defined?(DidYouMean::SpellChecker) && defined?(DidYouMean::Correctable) # rubocop:disable Naming/ConstantName
+    Module.new do
+      def to_s
+        super + DidYouMean.formatter.message_for(corrections)
+      end
+
+      def corrections
+        @corrections ||= self.class.const_get(:SpellChecker).new(self).corrections
+      end
+    end
+  end
+
+  # Bundler::Thor::Error is raised when it's caused by wrong usage of thor classes. Those
+  # errors have their backtrace suppressed and are nicely shown to the user.
+  #
+  # Errors that are caused by the developer, like declaring a method which
+  # overwrites a thor keyword, SHOULD NOT raise a Bundler::Thor::Error. This way, we
+  # ensure that developer errors are shown with full backtrace.
+  class Error < StandardError
+  end
+
+  # Raised when a command was not found.
+  class UndefinedCommandError < Error
+    class SpellChecker
+      attr_reader :error
+
+      def initialize(error)
+        @error = error
+      end
+
+      def corrections
+        @corrections ||= spell_checker.correct(error.command).map(&:inspect)
+      end
+
+      def spell_checker
+        DidYouMean::SpellChecker.new(dictionary: error.all_commands)
+      end
+    end
+
+    attr_reader :command, :all_commands
+
+    def initialize(command, all_commands, namespace)
+      @command = command
+      @all_commands = all_commands
+
+      message = "Could not find command #{command.inspect}"
+      message = namespace ? "#{message} in #{namespace.inspect} namespace." : "#{message}."
+
+      super(message)
+    end
+
+    prepend Correctable if Correctable
+  end
+  UndefinedTaskError = UndefinedCommandError
+
+  class AmbiguousCommandError < Error
+  end
+  AmbiguousTaskError = AmbiguousCommandError
+
+  # Raised when a command was found, but not invoked properly.
+  class InvocationError < Error
+  end
+
+  class UnknownArgumentError < Error
+    class SpellChecker
+      attr_reader :error
+
+      def initialize(error)
+        @error = error
+      end
+
+      def corrections
+        @corrections ||=
+          error.unknown.flat_map { |unknown| spell_checker.correct(unknown) }.uniq.map(&:inspect)
+      end
+
+      def spell_checker
+        @spell_checker ||= DidYouMean::SpellChecker.new(dictionary: error.switches)
+      end
+    end
+
+    attr_reader :switches, :unknown
+
+    def initialize(switches, unknown)
+      @switches = switches
+      @unknown = unknown
+
+      super("Unknown switches #{unknown.map(&:inspect).join(', ')}")
+    end
+
+    prepend Correctable if Correctable
+  end
+
+  class RequiredArgumentMissingError < InvocationError
+  end
+
+  class MalformattedArgumentError < InvocationError
+  end
+
+  class ExclusiveArgumentError < InvocationError
+  end
+
+  class AtLeastOneRequiredArgumentError < InvocationError
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/group.rb b/lib/bundler/vendor/thor/lib/thor/group.rb
new file mode 100644
index 0000000000..30bc311294
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/group.rb
@@ -0,0 +1,292 @@
+require_relative "base"
+
+# Bundler::Thor has a special class called Bundler::Thor::Group. The main difference to Bundler::Thor class
+# is that it invokes all commands at once. It also include some methods that allows
+# invocations to be done at the class method, which are not available to Bundler::Thor
+# commands.
+class Bundler::Thor::Group
+  class << self
+    # The description for this Bundler::Thor::Group. If none is provided, but a source root
+    # exists, tries to find the USAGE one folder above it, otherwise searches
+    # in the superclass.
+    #
+    # ==== Parameters
+    # description<String>:: The description for this Bundler::Thor::Group.
+    #
+    def desc(description = nil)
+      if description
+        @desc = description
+      else
+        @desc ||= from_superclass(:desc, nil)
+      end
+    end
+
+    # Prints help information.
+    #
+    # ==== Options
+    # short:: When true, shows only usage.
+    #
+    def help(shell)
+      shell.say "Usage:"
+      shell.say "  #{banner}\n"
+      shell.say
+      class_options_help(shell)
+      shell.say desc if desc
+    end
+
+    # Stores invocations for this class merging with superclass values.
+    #
+    def invocations #:nodoc:
+      @invocations ||= from_superclass(:invocations, {})
+    end
+
+    # Stores invocation blocks used on invoke_from_option.
+    #
+    def invocation_blocks #:nodoc:
+      @invocation_blocks ||= from_superclass(:invocation_blocks, {})
+    end
+
+    # Invoke the given namespace or class given. It adds an instance
+    # method that will invoke the klass and command. You can give a block to
+    # configure how it will be invoked.
+    #
+    # The namespace/class given will have its options showed on the help
+    # usage. Check invoke_from_option for more information.
+    #
+    def invoke(*names, &block)
+      options = names.last.is_a?(Hash) ? names.pop : {}
+      verbose = options.fetch(:verbose, true)
+
+      names.each do |name|
+        invocations[name] = false
+        invocation_blocks[name] = block if block_given?
+
+        class_eval <<-METHOD, __FILE__, __LINE__ + 1
+          def _invoke_#{name.to_s.gsub(/\W/, '_')}
+            klass, command = self.class.prepare_for_invocation(nil, #{name.inspect})
+
+            if klass
+              say_status :invoke, #{name.inspect}, #{verbose.inspect}
+              block = self.class.invocation_blocks[#{name.inspect}]
+              _invoke_for_class_method klass, command, &block
+            else
+              say_status :error, %(#{name.inspect} [not found]), :red
+            end
+          end
+        METHOD
+      end
+    end
+
+    # Invoke a thor class based on the value supplied by the user to the
+    # given option named "name". A class option must be created before this
+    # method is invoked for each name given.
+    #
+    # ==== Examples
+    #
+    #   class GemGenerator < Bundler::Thor::Group
+    #     class_option :test_framework, :type => :string
+    #     invoke_from_option :test_framework
+    #   end
+    #
+    # ==== Boolean options
+    #
+    # In some cases, you want to invoke a thor class if some option is true or
+    # false. This is automatically handled by invoke_from_option. Then the
+    # option name is used to invoke the generator.
+    #
+    # ==== Preparing for invocation
+    #
+    # In some cases you want to customize how a specified hook is going to be
+    # invoked. You can do that by overwriting the class method
+    # prepare_for_invocation. The class method must necessarily return a klass
+    # and an optional command.
+    #
+    # ==== Custom invocations
+    #
+    # You can also supply a block to customize how the option is going to be
+    # invoked. The block receives two parameters, an instance of the current
+    # class and the klass to be invoked.
+    #
+    def invoke_from_option(*names, &block)
+      options = names.last.is_a?(Hash) ? names.pop : {}
+      verbose = options.fetch(:verbose, :white)
+
+      names.each do |name|
+        unless class_options.key?(name)
+          raise ArgumentError, "You have to define the option #{name.inspect} " \
+                              "before setting invoke_from_option."
+        end
+
+        invocations[name] = true
+        invocation_blocks[name] = block if block_given?
+
+        class_eval <<-METHOD, __FILE__, __LINE__ + 1
+          def _invoke_from_option_#{name.to_s.gsub(/\W/, '_')}
+            return unless options[#{name.inspect}]
+
+            value = options[#{name.inspect}]
+            value = #{name.inspect} if TrueClass === value
+            klass, command = self.class.prepare_for_invocation(#{name.inspect}, value)
+
+            if klass
+              say_status :invoke, value, #{verbose.inspect}
+              block = self.class.invocation_blocks[#{name.inspect}]
+              _invoke_for_class_method klass, command, &block
+            else
+              say_status :error, %(\#{value} [not found]), :red
+            end
+          end
+        METHOD
+      end
+    end
+
+    # Remove a previously added invocation.
+    #
+    # ==== Examples
+    #
+    #   remove_invocation :test_framework
+    #
+    def remove_invocation(*names)
+      names.each do |name|
+        remove_command(name)
+        remove_class_option(name)
+        invocations.delete(name)
+        invocation_blocks.delete(name)
+      end
+    end
+
+    # Overwrite class options help to allow invoked generators options to be
+    # shown recursively when invoking a generator.
+    #
+    def class_options_help(shell, groups = {}) #:nodoc:
+      get_options_from_invocations(groups, class_options) do |klass|
+        klass.send(:get_options_from_invocations, groups, class_options)
+      end
+      super(shell, groups)
+    end
+
+    # Get invocations array and merge options from invocations. Those
+    # options are added to group_options hash. Options that already exists
+    # in base_options are not added twice.
+    #
+    def get_options_from_invocations(group_options, base_options) #:nodoc:
+      invocations.each do |name, from_option|
+        value = if from_option
+          option = class_options[name]
+          option.type == :boolean ? name : option.default
+        else
+          name
+        end
+        next unless value
+
+        klass, _ = prepare_for_invocation(name, value)
+        next unless klass && klass.respond_to?(:class_options)
+
+        value = value.to_s
+        human_name = value.respond_to?(:classify) ? value.classify : value
+
+        group_options[human_name] ||= []
+        group_options[human_name] += klass.class_options.values.select do |class_option|
+          base_options[class_option.name.to_sym].nil? && class_option.group.nil? &&
+            !group_options.values.flatten.any? { |i| i.name == class_option.name }
+        end
+
+        yield klass if block_given?
+      end
+    end
+
+    # Returns commands ready to be printed.
+    def printable_commands(*)
+      item = []
+      item << banner
+      item << (desc ? "# #{desc.gsub(/\s+/m, ' ')}" : "")
+      [item]
+    end
+    alias_method :printable_tasks, :printable_commands
+
+    def handle_argument_error(command, error, _args, arity) #:nodoc:
+      msg = "#{basename} #{command.name} takes #{arity} argument".dup
+      msg << "s" if arity > 1
+      msg << ", but it should not."
+      raise error, msg
+    end
+
+    # Checks if a specified command exists.
+    #
+    # ==== Parameters
+    # command_name<String>:: The name of the command to check for existence.
+    #
+    # ==== Returns
+    # Boolean:: +true+ if the command exists, +false+ otherwise.
+    def command_exists?(command_name) #:nodoc:
+      commands.keys.include?(command_name)
+    end
+
+  protected
+
+    # The method responsible for dispatching given the args.
+    def dispatch(command, given_args, given_opts, config) #:nodoc:
+      if Bundler::Thor::HELP_MAPPINGS.include?(given_args.first)
+        help(config[:shell])
+        return
+      end
+
+      args, opts = Bundler::Thor::Options.split(given_args)
+      opts = given_opts || opts
+
+      instance = new(args, opts, config)
+      yield instance if block_given?
+
+      if command
+        instance.invoke_command(all_commands[command])
+      else
+        instance.invoke_all
+      end
+    end
+
+    # The banner for this class. You can customize it if you are invoking the
+    # thor class by another ways which is not the Bundler::Thor::Runner.
+    def banner
+      "#{basename} #{self_command.formatted_usage(self, false)}"
+    end
+
+    # Represents the whole class as a command.
+    def self_command #:nodoc:
+      Bundler::Thor::DynamicCommand.new(namespace, class_options)
+    end
+    alias_method :self_task, :self_command
+
+    def baseclass #:nodoc:
+      Bundler::Thor::Group
+    end
+
+    def create_command(meth) #:nodoc:
+      commands[meth.to_s] = Bundler::Thor::Command.new(meth, nil, nil, nil, nil)
+      true
+    end
+    alias_method :create_task, :create_command
+  end
+
+  include Bundler::Thor::Base
+
+protected
+
+  # Shortcut to invoke with padding and block handling. Use internally by
+  # invoke and invoke_from_option class methods.
+  def _invoke_for_class_method(klass, command = nil, *args, &block) #:nodoc:
+    with_padding do
+      if block
+        case block.arity
+        when 3
+          yield(self, klass, command)
+        when 2
+          yield(self, klass)
+        when 1
+          instance_exec(klass, &block)
+        end
+      else
+        invoke klass, command, *args
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/invocation.rb b/lib/bundler/vendor/thor/lib/thor/invocation.rb
new file mode 100644
index 0000000000..5ce74710ba
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/invocation.rb
@@ -0,0 +1,178 @@
+class Bundler::Thor
+  module Invocation
+    def self.included(base) #:nodoc:
+      super(base)
+      base.extend ClassMethods
+    end
+
+    module ClassMethods
+      # This method is responsible for receiving a name and find the proper
+      # class and command for it. The key is an optional parameter which is
+      # available only in class methods invocations (i.e. in Bundler::Thor::Group).
+      def prepare_for_invocation(key, name) #:nodoc:
+        case name
+        when Symbol, String
+          Bundler::Thor::Util.find_class_and_command_by_namespace(name.to_s, !key)
+        else
+          name
+        end
+      end
+    end
+
+    # Make initializer aware of invocations and the initialization args.
+    def initialize(args = [], options = {}, config = {}, &block) #:nodoc:
+      @_invocations = config[:invocations] || Hash.new { |h, k| h[k] = [] }
+      @_initializer = [args, options, config]
+      super
+    end
+
+    # Make the current command chain accessible with in a Bundler::Thor-(sub)command
+    def current_command_chain
+      @_invocations.values.flatten.map(&:to_sym)
+    end
+
+    # Receives a name and invokes it. The name can be a string (either "command" or
+    # "namespace:command"), a Bundler::Thor::Command, a Class or a Bundler::Thor instance. If the
+    # command cannot be guessed by name, it can also be supplied as second argument.
+    #
+    # You can also supply the arguments, options and configuration values for
+    # the command to be invoked, if none is given, the same values used to
+    # initialize the invoker are used to initialize the invoked.
+    #
+    # When no name is given, it will invoke the default command of the current class.
+    #
+    # ==== Examples
+    #
+    #   class A < Bundler::Thor
+    #     def foo
+    #       invoke :bar
+    #       invoke "b:hello", ["Erik"]
+    #     end
+    #
+    #     def bar
+    #       invoke "b:hello", ["Erik"]
+    #     end
+    #   end
+    #
+    #   class B < Bundler::Thor
+    #     def hello(name)
+    #       puts "hello #{name}"
+    #     end
+    #   end
+    #
+    # You can notice that the method "foo" above invokes two commands: "bar",
+    # which belongs to the same class and "hello" which belongs to the class B.
+    #
+    # By using an invocation system you ensure that a command is invoked only once.
+    # In the example above, invoking "foo" will invoke "b:hello" just once, even
+    # if it's invoked later by "bar" method.
+    #
+    # When class A invokes class B, all arguments used on A initialization are
+    # supplied to B. This allows lazy parse of options. Let's suppose you have
+    # some rspec commands:
+    #
+    #   class Rspec < Bundler::Thor::Group
+    #     class_option :mock_framework, :type => :string, :default => :rr
+    #
+    #     def invoke_mock_framework
+    #       invoke "rspec:#{options[:mock_framework]}"
+    #     end
+    #   end
+    #
+    # As you noticed, it invokes the given mock framework, which might have its
+    # own options:
+    #
+    #   class Rspec::RR < Bundler::Thor::Group
+    #     class_option :style, :type => :string, :default => :mock
+    #   end
+    #
+    # Since it's not rspec concern to parse mock framework options, when RR
+    # is invoked all options are parsed again, so RR can extract only the options
+    # that it's going to use.
+    #
+    # If you want Rspec::RR to be initialized with its own set of options, you
+    # have to do that explicitly:
+    #
+    #   invoke "rspec:rr", [], :style => :foo
+    #
+    # Besides giving an instance, you can also give a class to invoke:
+    #
+    #   invoke Rspec::RR, [], :style => :foo
+    #
+    def invoke(name = nil, *args)
+      if name.nil?
+        warn "[Bundler::Thor] Calling invoke() without argument is deprecated. Please use invoke_all instead.\n#{caller.join("\n")}"
+        return invoke_all
+      end
+
+      args.unshift(nil) if args.first.is_a?(Array) || args.first.nil?
+      command, args, opts, config = args
+
+      klass, command = _retrieve_class_and_command(name, command)
+      raise "Missing Bundler::Thor class for invoke #{name}" unless klass
+      raise "Expected Bundler::Thor class, got #{klass}" unless klass <= Bundler::Thor::Base
+
+      args, opts, config = _parse_initialization_options(args, opts, config)
+      klass.send(:dispatch, command, args, opts, config) do |instance|
+        instance.parent_options = options
+      end
+    end
+
+    # Invoke the given command if the given args.
+    def invoke_command(command, *args) #:nodoc:
+      current = @_invocations[self.class]
+
+      unless current.include?(command.name)
+        current << command.name
+        command.run(self, *args)
+      end
+    end
+    alias_method :invoke_task, :invoke_command
+
+    # Invoke all commands for the current instance.
+    def invoke_all #:nodoc:
+      self.class.all_commands.map { |_, command| invoke_command(command) }
+    end
+
+    # Invokes using shell padding.
+    def invoke_with_padding(*args)
+      with_padding { invoke(*args) }
+    end
+
+  protected
+
+    # Configuration values that are shared between invocations.
+    def _shared_configuration #:nodoc:
+      {invocations: @_invocations}
+    end
+
+    # This method simply retrieves the class and command to be invoked.
+    # If the name is nil or the given name is a command in the current class,
+    # use the given name and return self as class. Otherwise, call
+    # prepare_for_invocation in the current class.
+    def _retrieve_class_and_command(name, sent_command = nil) #:nodoc:
+      if name.nil?
+        [self.class, nil]
+      elsif self.class.all_commands[name.to_s]
+        [self.class, name.to_s]
+      else
+        klass, command = self.class.prepare_for_invocation(nil, name)
+        [klass, command || sent_command]
+      end
+    end
+    alias_method :_retrieve_class_and_task, :_retrieve_class_and_command
+
+    # Initialize klass using values stored in the @_initializer.
+    def _parse_initialization_options(args, opts, config) #:nodoc:
+      stored_args, stored_opts, stored_config = @_initializer
+
+      args ||= stored_args.dup
+      opts ||= stored_opts.dup
+
+      config ||= {}
+      config = stored_config.merge(_shared_configuration).merge!(config)
+
+      [args, opts, config]
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/line_editor.rb b/lib/bundler/vendor/thor/lib/thor/line_editor.rb
new file mode 100644
index 0000000000..5c0c336e7a
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/line_editor.rb
@@ -0,0 +1,17 @@
+require_relative "line_editor/basic"
+require_relative "line_editor/readline"
+
+class Bundler::Thor
+  module LineEditor
+    def self.readline(prompt, options = {})
+      best_available.new(prompt, options).readline
+    end
+
+    def self.best_available
+      [
+        Bundler::Thor::LineEditor::Readline,
+        Bundler::Thor::LineEditor::Basic
+      ].detect(&:available?)
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/line_editor/basic.rb b/lib/bundler/vendor/thor/lib/thor/line_editor/basic.rb
new file mode 100644
index 0000000000..fe3d7c998f
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/line_editor/basic.rb
@@ -0,0 +1,37 @@
+class Bundler::Thor
+  module LineEditor
+    class Basic
+      attr_reader :prompt, :options
+
+      def self.available?
+        true
+      end
+
+      def initialize(prompt, options)
+        @prompt = prompt
+        @options = options
+      end
+
+      def readline
+        $stdout.print(prompt)
+        get_input
+      end
+
+    private
+
+      def get_input
+        if echo?
+          $stdin.gets
+        else
+          # Lazy-load io/console since it is gem-ified as of 2.3
+          require "io/console"
+          $stdin.noecho(&:gets)
+        end
+      end
+
+      def echo?
+        options.fetch(:echo, true)
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/line_editor/readline.rb b/lib/bundler/vendor/thor/lib/thor/line_editor/readline.rb
new file mode 100644
index 0000000000..120eadd06a
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/line_editor/readline.rb
@@ -0,0 +1,88 @@
+class Bundler::Thor
+  module LineEditor
+    class Readline < Basic
+      def self.available?
+        begin
+          require "readline"
+        rescue LoadError
+        end
+
+        Object.const_defined?(:Readline)
+      end
+
+      def readline
+        if echo?
+          ::Readline.completion_append_character = nil
+          # rb-readline does not allow Readline.completion_proc= to receive nil.
+          if complete = completion_proc
+            ::Readline.completion_proc = complete
+          end
+          ::Readline.readline(prompt, add_to_history?)
+        else
+          super
+        end
+      end
+
+    private
+
+      def add_to_history?
+        options.fetch(:add_to_history, true)
+      end
+
+      def completion_proc
+        if use_path_completion?
+          proc { |text| PathCompletion.new(text).matches }
+        elsif completion_options.any?
+          proc do |text|
+            completion_options.select { |option| option.start_with?(text) }
+          end
+        end
+      end
+
+      def completion_options
+        options.fetch(:limited_to, [])
+      end
+
+      def use_path_completion?
+        options.fetch(:path, false)
+      end
+
+      class PathCompletion
+        attr_reader :text
+        private :text
+
+        def initialize(text)
+          @text = text
+        end
+
+        def matches
+          relative_matches
+        end
+
+      private
+
+        def relative_matches
+          absolute_matches.map { |path| path.sub(base_path, "") }
+        end
+
+        def absolute_matches
+          Dir[glob_pattern].map do |path|
+            if File.directory?(path)
+              "#{path}/"
+            else
+              path
+            end
+          end
+        end
+
+        def glob_pattern
+          "#{base_path}#{text}*"
+        end
+
+        def base_path
+          "#{Dir.pwd}/"
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/nested_context.rb b/lib/bundler/vendor/thor/lib/thor/nested_context.rb
new file mode 100644
index 0000000000..7d60cb1c12
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/nested_context.rb
@@ -0,0 +1,29 @@
+class Bundler::Thor
+  class NestedContext
+    def initialize
+      @depth = 0
+    end
+
+    def enter
+      push
+
+      yield
+    ensure
+      pop
+    end
+
+    def entered?
+      @depth.positive?
+    end
+
+  private
+
+    def push
+      @depth += 1
+    end
+
+    def pop
+      @depth -= 1
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/parser.rb b/lib/bundler/vendor/thor/lib/thor/parser.rb
new file mode 100644
index 0000000000..45394732ca
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/parser.rb
@@ -0,0 +1,4 @@
+require_relative "parser/argument"
+require_relative "parser/arguments"
+require_relative "parser/option"
+require_relative "parser/options"
diff --git a/lib/bundler/vendor/thor/lib/thor/parser/argument.rb b/lib/bundler/vendor/thor/lib/thor/parser/argument.rb
new file mode 100644
index 0000000000..ee9db4ad8a
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/parser/argument.rb
@@ -0,0 +1,86 @@
+class Bundler::Thor
+  class Argument #:nodoc:
+    VALID_TYPES = [:numeric, :hash, :array, :string]
+
+    attr_reader :name, :description, :enum, :required, :type, :default, :banner
+    alias_method :human_name, :name
+
+    def initialize(name, options = {})
+      class_name = self.class.name.split("::").last
+
+      type = options[:type]
+
+      raise ArgumentError, "#{class_name} name can't be nil."                         if name.nil?
+      raise ArgumentError, "Type :#{type} is not valid for #{class_name.downcase}s."  if type && !valid_type?(type)
+
+      @name        = name.to_s
+      @description = options[:desc]
+      @required    = options.key?(:required) ? options[:required] : true
+      @type        = (type || :string).to_sym
+      @default     = options[:default]
+      @banner      = options[:banner] || default_banner
+      @enum        = options[:enum]
+
+      validate! # Trigger specific validations
+    end
+
+    def print_default
+      if @type == :array and @default.is_a?(Array)
+        @default.map(&:dump).join(" ")
+      else
+        @default
+      end
+    end
+
+    def usage
+      required? ? banner : "[#{banner}]"
+    end
+
+    def required?
+      required
+    end
+
+    def show_default?
+      case default
+      when Array, String, Hash
+        !default.empty?
+      else
+        default
+      end
+    end
+
+    def enum_to_s
+      if enum.respond_to? :join
+        enum.join(", ")
+      else
+        "#{enum.first}..#{enum.last}"
+      end
+    end
+
+  protected
+
+    def validate!
+      raise ArgumentError, "An argument cannot be required and have default value." if required? && !default.nil?
+      raise ArgumentError, "An argument cannot have an enum other than an enumerable." if @enum && !@enum.is_a?(Enumerable)
+    end
+
+    def valid_type?(type)
+      self.class::VALID_TYPES.include?(type.to_sym)
+    end
+
+    def default_banner
+      case type
+      when :boolean
+        nil
+      when :string, :default
+        human_name.upcase
+      when :numeric
+        "N"
+      when :hash
+        "key:value"
+      when :array
+        "one two three"
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/parser/arguments.rb b/lib/bundler/vendor/thor/lib/thor/parser/arguments.rb
new file mode 100644
index 0000000000..b6f9c9a37a
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/parser/arguments.rb
@@ -0,0 +1,195 @@
+class Bundler::Thor
+  class Arguments #:nodoc:
+    NUMERIC = /[-+]?(\d*\.\d+|\d+)/
+
+    # Receives an array of args and returns two arrays, one with arguments
+    # and one with switches.
+    #
+    def self.split(args)
+      arguments = []
+
+      args.each do |item|
+        break if item.is_a?(String) && item =~ /^-/
+        arguments << item
+      end
+
+      [arguments, args[Range.new(arguments.size, -1)]]
+    end
+
+    def self.parse(*args)
+      to_parse = args.pop
+      new(*args).parse(to_parse)
+    end
+
+    # Takes an array of Bundler::Thor::Argument objects.
+    #
+    def initialize(arguments = [])
+      @assigns = {}
+      @non_assigned_required = []
+      @switches = arguments
+
+      arguments.each do |argument|
+        if !argument.default.nil?
+          @assigns[argument.human_name] = argument.default.dup
+        elsif argument.required?
+          @non_assigned_required << argument
+        end
+      end
+    end
+
+    def parse(args)
+      @pile = args.dup
+
+      @switches.each do |argument|
+        break unless peek
+        @non_assigned_required.delete(argument)
+        @assigns[argument.human_name] = send(:"parse_#{argument.type}", argument.human_name)
+      end
+
+      check_requirement!
+      @assigns
+    end
+
+    def remaining
+      @pile
+    end
+
+  private
+
+    def no_or_skip?(arg)
+      arg =~ /^--(no|skip)-([-\w]+)$/
+      $2
+    end
+
+    def last?
+      @pile.empty?
+    end
+
+    def peek
+      @pile.first
+    end
+
+    def shift
+      @pile.shift
+    end
+
+    def unshift(arg)
+      if arg.is_a?(Array)
+        @pile = arg + @pile
+      else
+        @pile.unshift(arg)
+      end
+    end
+
+    def current_is_value?
+      peek && peek.to_s !~ /^-{1,2}\S+/
+    end
+
+    # Runs through the argument array getting strings that contains ":" and
+    # mark it as a hash:
+    #
+    #   [ "name:string", "age:integer" ]
+    #
+    # Becomes:
+    #
+    #   { "name" => "string", "age" => "integer" }
+    #
+    def parse_hash(name)
+      return shift if peek.is_a?(Hash)
+      hash = {}
+
+      while current_is_value? && peek.include?(":")
+        key, value = shift.split(":", 2)
+        raise MalformattedArgumentError, "You can't specify '#{key}' more than once in option '#{name}'; got #{key}:#{hash[key]} and #{key}:#{value}" if hash.include? key
+        hash[key] = value
+      end
+      hash
+    end
+
+    # Runs through the argument array getting all strings until no string is
+    # found or a switch is found.
+    #
+    #   ["a", "b", "c"]
+    #
+    # And returns it as an array:
+    #
+    #   ["a", "b", "c"]
+    #
+    def parse_array(name)
+      return shift if peek.is_a?(Array)
+
+      array = []
+
+      while current_is_value?
+        value = shift
+
+        if !value.empty?
+          validate_enum_value!(name, value, "Expected all values of '%s' to be one of %s; got %s")
+        end
+
+        array << value
+      end
+      array
+    end
+
+    # Check if the peek is numeric format and return a Float or Integer.
+    # Check if the peek is included in enum if enum is provided.
+    # Otherwise raises an error.
+    #
+    def parse_numeric(name)
+      return shift if peek.is_a?(Numeric)
+
+      unless peek =~ NUMERIC && $& == peek
+        raise MalformattedArgumentError, "Expected numeric value for '#{name}'; got #{peek.inspect}"
+      end
+
+      value = $&.index(".") ? shift.to_f : shift.to_i
+
+      validate_enum_value!(name, value, "Expected '%s' to be one of %s; got %s")
+
+      value
+    end
+
+    # Parse string:
+    # for --string-arg, just return the current value in the pile
+    # for --no-string-arg, nil
+    # Check if the peek is included in enum if enum is provided. Otherwise raises an error.
+    #
+    def parse_string(name)
+      if no_or_skip?(name)
+        nil
+      else
+        value = shift
+
+        validate_enum_value!(name, value, "Expected '%s' to be one of %s; got %s")
+
+        value
+      end
+    end
+
+    # Raises an error if the switch is an enum and the values aren't included on it.
+    #
+    def validate_enum_value!(name, value, message)
+      return unless @switches.is_a?(Hash)
+
+      switch = @switches[name]
+
+      return unless switch
+
+      if switch.enum && !switch.enum.include?(value)
+        raise MalformattedArgumentError, message % [name, switch.enum_to_s, value]
+      end
+    end
+
+    # Raises an error if @non_assigned_required array is not empty.
+    #
+    def check_requirement!
+      return if @non_assigned_required.empty?
+      names = @non_assigned_required.map do |o|
+        o.respond_to?(:switch_name) ? o.switch_name : o.human_name
+      end.join("', '")
+      class_name = self.class.name.split("::").last.downcase
+      raise RequiredArgumentMissingError, "No value provided for required #{class_name} '#{names}'"
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/parser/option.rb b/lib/bundler/vendor/thor/lib/thor/parser/option.rb
new file mode 100644
index 0000000000..72617c7e34
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/parser/option.rb
@@ -0,0 +1,178 @@
+class Bundler::Thor
+  class Option < Argument #:nodoc:
+    attr_reader :aliases, :group, :lazy_default, :hide, :repeatable
+
+    VALID_TYPES = [:boolean, :numeric, :hash, :array, :string]
+
+    def initialize(name, options = {})
+      @check_default_type = options[:check_default_type]
+      options[:required] = false unless options.key?(:required)
+      @repeatable     = options.fetch(:repeatable, false)
+      super
+      @lazy_default   = options[:lazy_default]
+      @group          = options[:group].to_s.capitalize if options[:group]
+      @aliases        = normalize_aliases(options[:aliases])
+      @hide           = options[:hide]
+    end
+
+    # This parse quick options given as method_options. It makes several
+    # assumptions, but you can be more specific using the option method.
+    #
+    #   parse :foo => "bar"
+    #   #=> Option foo with default value bar
+    #
+    #   parse [:foo, :baz] => "bar"
+    #   #=> Option foo with default value bar and alias :baz
+    #
+    #   parse :foo => :required
+    #   #=> Required option foo without default value
+    #
+    #   parse :foo => 2
+    #   #=> Option foo with default value 2 and type numeric
+    #
+    #   parse :foo => :numeric
+    #   #=> Option foo without default value and type numeric
+    #
+    #   parse :foo => true
+    #   #=> Option foo with default value true and type boolean
+    #
+    # The valid types are :boolean, :numeric, :hash, :array and :string. If none
+    # is given a default type is assumed. This default type accepts arguments as
+    # string (--foo=value) or booleans (just --foo).
+    #
+    # By default all options are optional, unless :required is given.
+    #
+    def self.parse(key, value)
+      if key.is_a?(Array)
+        name, *aliases = key
+      else
+        name = key
+        aliases = []
+      end
+
+      name    = name.to_s
+      default = value
+
+      type = case value
+      when Symbol
+        default = nil
+        if VALID_TYPES.include?(value)
+          value
+        elsif required = (value == :required) # rubocop:disable Lint/AssignmentInCondition
+          :string
+        end
+      when TrueClass, FalseClass
+        :boolean
+      when Numeric
+        :numeric
+      when Hash, Array, String
+        value.class.name.downcase.to_sym
+      end
+
+      new(name.to_s, required: required, type: type, default: default, aliases: aliases)
+    end
+
+    def switch_name
+      @switch_name ||= dasherized? ? name : dasherize(name)
+    end
+
+    def human_name
+      @human_name ||= dasherized? ? undasherize(name) : name
+    end
+
+    def usage(padding = 0)
+      sample = if banner && !banner.to_s.empty?
+        "#{switch_name}=#{banner}".dup
+      else
+        switch_name
+      end
+
+      sample = "[#{sample}]".dup unless required?
+
+      if boolean? && name != "force" && !name.match(/\A(no|skip)[\-_]/)
+        sample << ", [#{dasherize('no-' + human_name)}], [#{dasherize('skip-' + human_name)}]"
+      end
+
+      aliases_for_usage.ljust(padding) + sample
+    end
+
+    def aliases_for_usage
+      if aliases.empty?
+        ""
+      else
+        "#{aliases.join(', ')}, "
+      end
+    end
+
+    def show_default?
+      case default
+      when TrueClass, FalseClass
+        true
+      else
+        super
+      end
+    end
+
+    VALID_TYPES.each do |type|
+      class_eval <<-RUBY, __FILE__, __LINE__ + 1
+        def #{type}?
+          self.type == #{type.inspect}
+        end
+      RUBY
+    end
+
+  protected
+
+    def validate!
+      raise ArgumentError, "An option cannot be boolean and required." if boolean? && required?
+      validate_default_type!
+    end
+
+    def validate_default_type!
+      default_type = case @default
+      when nil
+        return
+      when TrueClass, FalseClass
+        required? ? :string : :boolean
+      when Numeric
+        :numeric
+      when Symbol
+        :string
+      when Hash, Array, String
+        @default.class.name.downcase.to_sym
+      end
+
+      expected_type = (@repeatable && @type != :hash) ? :array : @type
+
+      if default_type != expected_type
+        err = "Expected #{expected_type} default value for '#{switch_name}'; got #{@default.inspect} (#{default_type})"
+
+        if @check_default_type
+          raise ArgumentError, err
+        elsif @check_default_type == nil
+          Bundler::Thor.deprecation_warning "#{err}.\n" +
+            "This will be rejected in the future unless you explicitly pass the options `check_default_type: false`" +
+            " or call `allow_incompatible_default_type!` in your code"
+        end
+      end
+    end
+
+    def dasherized?
+      name.index("-") == 0
+    end
+
+    def undasherize(str)
+      str.sub(/^-{1,2}/, "")
+    end
+
+    def dasherize(str)
+      (str.length > 1 ? "--" : "-") + str.tr("_", "-")
+    end
+
+  private
+
+    def normalize_aliases(aliases)
+      Array(aliases).map { |short| short.to_s.sub(/^(?!\-)/, "-") }
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/parser/options.rb b/lib/bundler/vendor/thor/lib/thor/parser/options.rb
new file mode 100644
index 0000000000..fe22d989e5
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/parser/options.rb
@@ -0,0 +1,294 @@
+class Bundler::Thor
+  class Options < Arguments #:nodoc:
+    LONG_RE     = /^(--\w+(?:-\w+)*)$/
+    SHORT_RE    = /^(-[a-z])$/i
+    EQ_RE       = /^(--\w+(?:-\w+)*|-[a-z])=(.*)$/i
+    SHORT_SQ_RE = /^-([a-z]{2,})$/i # Allow either -x -v or -xv style for single char args
+    SHORT_NUM   = /^(-[a-z])#{NUMERIC}$/i
+    OPTS_END    = "--".freeze
+
+    # Receives a hash and makes it switches.
+    def self.to_switches(options)
+      options.map do |key, value|
+        case value
+        when true
+          "--#{key}"
+        when Array
+          "--#{key} #{value.map(&:inspect).join(' ')}"
+        when Hash
+          "--#{key} #{value.map { |k, v| "#{k}:#{v}" }.join(' ')}"
+        when nil, false
+          nil
+        else
+          "--#{key} #{value.inspect}"
+        end
+      end.compact.join(" ")
+    end
+
+    # Takes a hash of Bundler::Thor::Option and a hash with defaults.
+    #
+    # If +stop_on_unknown+ is true, #parse will stop as soon as it encounters
+    # an unknown option or a regular argument.
+    def initialize(hash_options = {}, defaults = {}, stop_on_unknown = false, disable_required_check = false, relations = {})
+      @stop_on_unknown = stop_on_unknown
+      @exclusives = (relations[:exclusive_option_names] || []).select{|array| !array.empty?}
+      @at_least_ones = (relations[:at_least_one_option_names] || []).select{|array| !array.empty?}
+      @disable_required_check = disable_required_check
+      options = hash_options.values
+      super(options)
+
+      # Add defaults
+      defaults.each do |key, value|
+        @assigns[key.to_s] = value
+        @non_assigned_required.delete(hash_options[key])
+      end
+
+      @shorts = {}
+      @switches = {}
+      @extra = []
+      @stopped_parsing_after_extra_index = nil
+      @is_treated_as_value = false
+
+      options.each do |option|
+        @switches[option.switch_name] = option
+
+        option.aliases.each do |name|
+          @shorts[name] ||= option.switch_name
+        end
+      end
+    end
+
+    def remaining
+      @extra
+    end
+
+    def peek
+      return super unless @parsing_options
+
+      result = super
+      if result == OPTS_END
+        shift
+        @parsing_options = false
+        @stopped_parsing_after_extra_index ||= @extra.size
+        super
+      else
+        result
+      end
+    end
+
+    def shift
+      @is_treated_as_value = false
+      super
+    end
+
+    def unshift(arg, is_value: false)
+      @is_treated_as_value = is_value
+      super(arg)
+    end
+
+    def parse(args) # rubocop:disable Metrics/MethodLength
+      @pile = args.dup
+      @is_treated_as_value = false
+      @parsing_options = true
+
+      while peek
+        if parsing_options?
+          match, is_switch = current_is_switch?
+          shifted = shift
+
+          if is_switch
+            case shifted
+            when SHORT_SQ_RE
+              unshift($1.split("").map { |f| "-#{f}" })
+              next
+            when EQ_RE
+              unshift($2, is_value: true)
+              switch = $1
+            when SHORT_NUM
+              unshift($2)
+              switch = $1
+            when LONG_RE, SHORT_RE
+              switch = $1
+            end
+
+            switch = normalize_switch(switch)
+            option = switch_option(switch)
+            result = parse_peek(switch, option)
+            assign_result!(option, result)
+          elsif @stop_on_unknown
+            @parsing_options = false
+            @extra << shifted
+            @stopped_parsing_after_extra_index ||= @extra.size
+            @extra << shift while peek
+            break
+          elsif match
+            @extra << shifted
+            @extra << shift while peek && peek !~ /^-/
+          else
+            @extra << shifted
+          end
+        else
+          @extra << shift
+        end
+      end
+
+      check_requirement! unless @disable_required_check
+      check_exclusive!
+      check_at_least_one!
+
+      assigns = Bundler::Thor::CoreExt::HashWithIndifferentAccess.new(@assigns)
+      assigns.freeze
+      assigns
+    end
+
+    def check_exclusive!
+      opts = @assigns.keys
+      # When option A and B are exclusive, if A and B are given at the same time,
+      # the difference of argument array size will decrease.
+      found = @exclusives.find{ |ex| (ex - opts).size < ex.size - 1 }
+      if found
+        names = names_to_switch_names(found & opts).map{|n| "'#{n}'"}
+        class_name = self.class.name.split("::").last.downcase
+        fail ExclusiveArgumentError, "Found exclusive #{class_name} #{names.join(", ")}"
+      end
+    end
+
+    def check_at_least_one!
+      opts = @assigns.keys
+      # When at least one is required of the options A and B,
+      # if the both options were not given, none? would be true.
+      found = @at_least_ones.find{ |one_reqs| one_reqs.none?{ |o| opts.include? o} }
+      if found
+        names = names_to_switch_names(found).map{|n| "'#{n}'"}
+        class_name = self.class.name.split("::").last.downcase
+        fail AtLeastOneRequiredArgumentError, "Not found at least one of required #{class_name} #{names.join(", ")}"
+      end
+    end
+
+    def check_unknown!
+      to_check = @stopped_parsing_after_extra_index ? @extra[0...@stopped_parsing_after_extra_index] : @extra
+
+      # an unknown option starts with - or -- and has no more --'s afterward.
+      unknown = to_check.select { |str| str =~ /^--?(?:(?!--).)*$/ }
+      raise UnknownArgumentError.new(@switches.keys, unknown) unless unknown.empty?
+    end
+
+  protected
+
+    # Option names changes to swith name or human name
+    def names_to_switch_names(names = [])
+      @switches.map do |_, o|
+        if names.include? o.name
+          o.respond_to?(:switch_name) ? o.switch_name : o.human_name
+        else
+          nil
+        end
+      end.compact
+    end
+
+    def assign_result!(option, result)
+      if option.repeatable && option.type == :hash
+        (@assigns[option.human_name] ||= {}).merge!(result)
+      elsif option.repeatable
+        (@assigns[option.human_name] ||= []) << result
+      else
+        @assigns[option.human_name] = result
+      end
+    end
+
+    # Check if the current value in peek is a registered switch.
+    #
+    # Two booleans are returned.  The first is true if the current value
+    # starts with a hyphen; the second is true if it is a registered switch.
+    def current_is_switch?
+      return [false, false] if @is_treated_as_value
+      case peek
+      when LONG_RE, SHORT_RE, EQ_RE, SHORT_NUM
+        [true, switch?($1)]
+      when SHORT_SQ_RE
+        [true, $1.split("").any? { |f| switch?("-#{f}") }]
+      else
+        [false, false]
+      end
+    end
+
+    def current_is_switch_formatted?
+      return false if @is_treated_as_value
+      case peek
+      when LONG_RE, SHORT_RE, EQ_RE, SHORT_NUM, SHORT_SQ_RE
+        true
+      else
+        false
+      end
+    end
+
+    def current_is_value?
+      return true if @is_treated_as_value
+      peek && (!parsing_options? || super)
+    end
+
+    def switch?(arg)
+      !switch_option(normalize_switch(arg)).nil?
+    end
+
+    def switch_option(arg)
+      if match = no_or_skip?(arg) # rubocop:disable Lint/AssignmentInCondition
+        @switches[arg] || @switches["--#{match}"]
+      else
+        @switches[arg]
+      end
+    end
+
+    # Check if the given argument is actually a shortcut.
+    #
+    def normalize_switch(arg)
+      (@shorts[arg] || arg).tr("_", "-")
+    end
+
+    def parsing_options?
+      peek
+      @parsing_options
+    end
+
+    # Parse boolean values which can be given as --foo=true or --foo for true values, or
+    # --foo=false, --no-foo or --skip-foo for false values.
+    #
+    def parse_boolean(switch)
+      if current_is_value?
+        if ["true", "TRUE", "t", "T", true].include?(peek)
+          shift
+          true
+        elsif ["false", "FALSE", "f", "F", false].include?(peek)
+          shift
+          false
+        else
+          @switches.key?(switch) || !no_or_skip?(switch)
+        end
+      else
+        @switches.key?(switch) || !no_or_skip?(switch)
+      end
+    end
+
+    # Parse the value at the peek analyzing if it requires an input or not.
+    #
+    def parse_peek(switch, option)
+      if parsing_options? && (current_is_switch_formatted? || last?)
+        if option.boolean?
+          # No problem for boolean types
+        elsif no_or_skip?(switch)
+          return nil # User set value to nil
+        elsif option.string? && !option.required?
+          # Return the default if there is one, else the human name
+          return option.lazy_default || option.default || option.human_name
+        elsif option.lazy_default
+          return option.lazy_default
+        else
+          raise MalformattedArgumentError, "No value provided for option '#{switch}'"
+        end
+      end
+
+      @non_assigned_required.delete(option)
+      send(:"parse_#{option.type}", switch)
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/rake_compat.rb b/lib/bundler/vendor/thor/lib/thor/rake_compat.rb
new file mode 100644
index 0000000000..c6a4653fc1
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/rake_compat.rb
@@ -0,0 +1,72 @@
+require "rake"
+require "rake/dsl_definition"
+
+class Bundler::Thor
+  # Adds a compatibility layer to your Bundler::Thor classes which allows you to use
+  # rake package tasks. For example, to use rspec rake tasks, one can do:
+  #
+  #   require 'bundler/vendor/thor/lib/thor/rake_compat'
+  #   require 'rspec/core/rake_task'
+  #
+  #   class Default < Bundler::Thor
+  #     include Bundler::Thor::RakeCompat
+  #
+  #     RSpec::Core::RakeTask.new(:spec) do |t|
+  #       t.spec_opts = ['--options', './.rspec']
+  #       t.spec_files = FileList['spec/**/*_spec.rb']
+  #     end
+  #   end
+  #
+  module RakeCompat
+    include Rake::DSL if defined?(Rake::DSL)
+
+    def self.rake_classes
+      @rake_classes ||= []
+    end
+
+    def self.included(base)
+      super(base)
+      # Hack. Make rakefile point to invoker, so rdoc task is generated properly.
+      rakefile = File.basename(caller[0].match(/(.*):\d+/)[1])
+      Rake.application.instance_variable_set(:@rakefile, rakefile)
+      rake_classes << base
+    end
+  end
+end
+
+# override task on (main), for compatibility with Rake 0.9
+instance_eval do
+  alias rake_namespace namespace
+
+  def task(*)
+    task = super
+
+    if klass = Bundler::Thor::RakeCompat.rake_classes.last # rubocop:disable Lint/AssignmentInCondition
+      non_namespaced_name = task.name.split(":").last
+
+      description = non_namespaced_name
+      description << task.arg_names.map { |n| n.to_s.upcase }.join(" ")
+      description.strip!
+
+      klass.desc description, Rake.application.last_description || non_namespaced_name
+      Rake.application.last_description = nil
+      klass.send :define_method, non_namespaced_name do |*args|
+        Rake::Task[task.name.to_sym].invoke(*args)
+      end
+    end
+
+    task
+  end
+
+  def namespace(name)
+    if klass = Bundler::Thor::RakeCompat.rake_classes.last # rubocop:disable Lint/AssignmentInCondition
+      const_name = Bundler::Thor::Util.camel_case(name.to_s).to_sym
+      klass.const_set(const_name, Class.new(Bundler::Thor))
+      new_klass = klass.const_get(const_name)
+      Bundler::Thor::RakeCompat.rake_classes << new_klass
+    end
+
+    super
+    Bundler::Thor::RakeCompat.rake_classes.pop
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/runner.rb b/lib/bundler/vendor/thor/lib/thor/runner.rb
new file mode 100644
index 0000000000..f0ce6df96c
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/runner.rb
@@ -0,0 +1,335 @@
+require_relative "../thor"
+require_relative "group"
+
+require "digest/sha2"
+require "pathname" unless defined?(Pathname)
+
+class Bundler::Thor::Runner < Bundler::Thor #:nodoc:
+  map "-T" => :list, "-i" => :install, "-u" => :update, "-v" => :version
+
+  def self.banner(command, all = false, subcommand = false)
+    "thor " + command.formatted_usage(self, all, subcommand)
+  end
+
+  def self.exit_on_failure?
+    true
+  end
+
+  # Override Bundler::Thor#help so it can give information about any class and any method.
+  #
+  def help(meth = nil)
+    if meth && !respond_to?(meth)
+      initialize_thorfiles(meth)
+      klass, command = Bundler::Thor::Util.find_class_and_command_by_namespace(meth)
+      self.class.handle_no_command_error(command, false) if klass.nil?
+      klass.start(["-h", command].compact, shell: shell)
+    else
+      super
+    end
+  end
+
+  # If a command is not found on Bundler::Thor::Runner, method missing is invoked and
+  # Bundler::Thor::Runner is then responsible for finding the command in all classes.
+  #
+  def method_missing(meth, *args)
+    meth = meth.to_s
+    initialize_thorfiles(meth)
+    klass, command = Bundler::Thor::Util.find_class_and_command_by_namespace(meth)
+    self.class.handle_no_command_error(command, false) if klass.nil?
+    args.unshift(command) if command
+    klass.start(args, shell: shell)
+  end
+
+  desc "install NAME", "Install an optionally named Bundler::Thor file into your system commands"
+  method_options as: :string, relative: :boolean, force: :boolean
+  def install(name) # rubocop:disable Metrics/MethodLength
+    initialize_thorfiles
+
+    is_uri  = name =~ %r{^https?\://}
+
+    if is_uri
+      base = name
+      package = :file
+      require "open-uri"
+      begin
+        contents = URI.open(name, &:read)
+      rescue OpenURI::HTTPError
+        raise Error, "Error opening URI '#{name}'"
+      end
+    else
+      # If a directory name is provided as the argument, look for a 'main.thor'
+      # command in said directory.
+      begin
+        if File.directory?(File.expand_path(name))
+          base = File.join(name, "main.thor")
+          package = :directory
+          contents = File.open(base, &:read)
+        else
+          base = name
+          package = :file
+          require "open-uri"
+          contents = URI.open(name, &:read)
+        end
+      rescue Errno::ENOENT
+        raise Error, "Error opening file '#{name}'"
+      end
+    end
+
+    say "Your Thorfile contains:"
+    say contents
+
+    unless options["force"]
+      return false if no?("Do you wish to continue [y/N]?")
+    end
+
+    as = options["as"] || begin
+      first_line = contents.split("\n")[0]
+      (match = first_line.match(/\s*#\s*module:\s*([^\n]*)/)) ? match[1].strip : nil
+    end
+
+    unless as
+      basename = File.basename(name)
+      as = ask("Please specify a name for #{name} in the system repository [#{basename}]:")
+      as = basename if as.empty?
+    end
+
+    location = if options[:relative] || is_uri
+      name
+    else
+      File.expand_path(name)
+    end
+
+    thor_yaml[as] = {
+      filename: Digest::SHA256.hexdigest(name + as),
+      location: location,
+      namespaces: Bundler::Thor::Util.namespaces_in_content(contents, base)
+    }
+
+    save_yaml(thor_yaml)
+    say "Storing thor file in your system repository"
+    destination = File.join(thor_root, thor_yaml[as][:filename])
+
+    if package == :file
+      File.open(destination, "w") { |f| f.puts contents }
+    else
+      require "fileutils"
+      FileUtils.cp_r(name, destination)
+    end
+
+    thor_yaml[as][:filename] # Indicate success
+  end
+
+  desc "version", "Show Bundler::Thor version"
+  def version
+    require_relative "version"
+    say "Bundler::Thor #{Bundler::Thor::VERSION}"
+  end
+
+  desc "uninstall NAME", "Uninstall a named Bundler::Thor module"
+  def uninstall(name)
+    raise Error, "Can't find module '#{name}'" unless thor_yaml[name]
+    say "Uninstalling #{name}."
+    require "fileutils"
+    FileUtils.rm_rf(File.join(thor_root, (thor_yaml[name][:filename]).to_s))
+
+    thor_yaml.delete(name)
+    save_yaml(thor_yaml)
+
+    puts "Done."
+  end
+
+  desc "update NAME", "Update a Bundler::Thor file from its original location"
+  def update(name)
+    raise Error, "Can't find module '#{name}'" if !thor_yaml[name] || !thor_yaml[name][:location]
+
+    say "Updating '#{name}' from #{thor_yaml[name][:location]}"
+
+    old_filename = thor_yaml[name][:filename]
+    self.options = options.merge("as" => name)
+
+    if File.directory? File.expand_path(name)
+      require "fileutils"
+      FileUtils.rm_rf(File.join(thor_root, old_filename))
+
+      thor_yaml.delete(old_filename)
+      save_yaml(thor_yaml)
+
+      filename = install(name)
+    else
+      filename = install(thor_yaml[name][:location])
+    end
+
+    File.delete(File.join(thor_root, old_filename)) unless filename == old_filename
+  end
+
+  desc "installed", "List the installed Bundler::Thor modules and commands"
+  method_options internal: :boolean
+  def installed
+    initialize_thorfiles(nil, true)
+    display_klasses(true, options["internal"])
+  end
+
+  desc "list [SEARCH]", "List the available thor commands (--substring means .*SEARCH)"
+  method_options substring: :boolean, group: :string, all: :boolean, debug: :boolean
+  def list(search = "")
+    initialize_thorfiles
+
+    search = ".*#{search}" if options["substring"]
+    search = /^#{search}.*/i
+    group  = options[:group] || "standard"
+
+    klasses = Bundler::Thor::Base.subclasses.select do |k|
+      (options[:all] || k.group == group) && k.namespace =~ search
+    end
+
+    display_klasses(false, false, klasses)
+  end
+
+private
+
+  def thor_root
+    Bundler::Thor::Util.thor_root
+  end
+
+  def thor_yaml
+    @thor_yaml ||= begin
+      yaml_file = File.join(thor_root, "thor.yml")
+      require "yaml"
+      yaml = YAML.load_file(yaml_file) if File.exist?(yaml_file)
+      yaml || {}
+    end
+  end
+
+  # Save the yaml file. If none exists in thor root, creates one.
+  #
+  def save_yaml(yaml)
+    yaml_file = File.join(thor_root, "thor.yml")
+
+    unless File.exist?(yaml_file)
+      require "fileutils"
+      FileUtils.mkdir_p(thor_root)
+      yaml_file = File.join(thor_root, "thor.yml")
+      FileUtils.touch(yaml_file)
+    end
+
+    File.open(yaml_file, "w") { |f| f.puts yaml.to_yaml }
+  end
+
+  # Load the Thorfiles. If relevant_to is supplied, looks for specific files
+  # in the thor_root instead of loading them all.
+  #
+  # By default, it also traverses the current path until find Bundler::Thor files, as
+  # described in thorfiles. This look up can be skipped by supplying
+  # skip_lookup true.
+  #
+  def initialize_thorfiles(relevant_to = nil, skip_lookup = false)
+    thorfiles(relevant_to, skip_lookup).each do |f|
+      Bundler::Thor::Util.load_thorfile(f, nil, options[:debug]) unless Bundler::Thor::Base.subclass_files.keys.include?(File.expand_path(f))
+    end
+  end
+
+  # Finds Thorfiles by traversing from your current directory down to the root
+  # directory of your system. If at any time we find a Bundler::Thor file, we stop.
+  #
+  # We also ensure that system-wide Thorfiles are loaded first, so local
+  # Thorfiles can override them.
+  #
+  # ==== Example
+  #
+  # If we start at /Users/wycats/dev/thor ...
+  #
+  # 1. /Users/wycats/dev/thor
+  # 2. /Users/wycats/dev
+  # 3. /Users/wycats <-- we find a Thorfile here, so we stop
+  #
+  # Suppose we start at c:\Documents and Settings\james\dev\thor ...
+  #
+  # 1. c:\Documents and Settings\james\dev\thor
+  # 2. c:\Documents and Settings\james\dev
+  # 3. c:\Documents and Settings\james
+  # 4. c:\Documents and Settings
+  # 5. c:\ <-- no Thorfiles found!
+  #
+  def thorfiles(relevant_to = nil, skip_lookup = false)
+    thorfiles = []
+
+    unless skip_lookup
+      Pathname.pwd.ascend do |path|
+        thorfiles = Bundler::Thor::Util.globs_for(path).map { |g| Dir[g] }.flatten
+        break unless thorfiles.empty?
+      end
+    end
+
+    files  = (relevant_to ? thorfiles_relevant_to(relevant_to) : Bundler::Thor::Util.thor_root_glob)
+    files += thorfiles
+    files -= ["#{thor_root}/thor.yml"]
+
+    files.map! do |file|
+      File.directory?(file) ? File.join(file, "main.thor") : file
+    end
+  end
+
+  # Load Thorfiles relevant to the given method. If you provide "foo:bar" it
+  # will load all thor files in the thor.yaml that has "foo" e "foo:bar"
+  # namespaces registered.
+  #
+  def thorfiles_relevant_to(meth)
+    lookup = [meth, meth.split(":")[0...-1].join(":")]
+
+    files = thor_yaml.select do |_, v|
+      v[:namespaces] && !(v[:namespaces] & lookup).empty?
+    end
+
+    files.map { |_, v| File.join(thor_root, (v[:filename]).to_s) }
+  end
+
+  # Display information about the given klasses. If with_module is given,
+  # it shows a table with information extracted from the yaml file.
+  #
+  def display_klasses(with_modules = false, show_internal = false, klasses = Bundler::Thor::Base.subclasses)
+    klasses -= [Bundler::Thor, Bundler::Thor::Runner, Bundler::Thor::Group] unless show_internal
+
+    raise Error, "No Bundler::Thor commands available" if klasses.empty?
+    show_modules if with_modules && !thor_yaml.empty?
+
+    list = Hash.new { |h, k| h[k] = [] }
+    groups = klasses.select { |k| k.ancestors.include?(Bundler::Thor::Group) }
+
+    # Get classes which inherit from Bundler::Thor
+    (klasses - groups).each { |k| list[k.namespace.split(":").first] += k.printable_commands(false) }
+
+    # Get classes which inherit from Bundler::Thor::Base
+    groups.map! { |k| k.printable_commands(false).first }
+    list["root"] = groups
+
+    # Order namespaces with default coming first
+    list = list.sort { |a, b| a[0].sub(/^default/, "") <=> b[0].sub(/^default/, "") }
+    list.each { |n, commands| display_commands(n, commands) unless commands.empty? }
+  end
+
+  def display_commands(namespace, list) #:nodoc:
+    list.sort! { |a, b| a[0] <=> b[0] }
+
+    say shell.set_color(namespace, :blue, true)
+    say "-" * namespace.size
+
+    print_table(list, truncate: true)
+    say
+  end
+  alias_method :display_tasks, :display_commands
+
+  def show_modules #:nodoc:
+    info = []
+    labels = %w(Modules Namespaces)
+
+    info << labels
+    info << ["-" * labels[0].size, "-" * labels[1].size]
+
+    thor_yaml.each do |name, hash|
+      info << [name, hash[:namespaces].join(", ")]
+    end
+
+    print_table info
+    say ""
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/shell.rb b/lib/bundler/vendor/thor/lib/thor/shell.rb
new file mode 100644
index 0000000000..265f3ba046
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/shell.rb
@@ -0,0 +1,81 @@
+require "rbconfig"
+
+class Bundler::Thor
+  module Base
+    class << self
+      attr_writer :shell
+
+      # Returns the shell used in all Bundler::Thor classes. If you are in a Unix platform
+      # it will use a colored log, otherwise it will use a basic one without color.
+      #
+      def shell
+        @shell ||= if ENV["THOR_SHELL"] && !ENV["THOR_SHELL"].empty?
+          Bundler::Thor::Shell.const_get(ENV["THOR_SHELL"])
+        elsif RbConfig::CONFIG["host_os"] =~ /mswin|mingw/ && !ENV["ANSICON"]
+          Bundler::Thor::Shell::Basic
+        else
+          Bundler::Thor::Shell::Color
+        end
+      end
+    end
+  end
+
+  module Shell
+    SHELL_DELEGATED_METHODS = [:ask, :error, :set_color, :yes?, :no?, :say, :say_error, :say_status, :print_in_columns, :print_table, :print_wrapped, :file_collision, :terminal_width]
+    attr_writer :shell
+
+    autoload :Basic, File.expand_path("shell/basic", __dir__)
+    autoload :Color, File.expand_path("shell/color", __dir__)
+    autoload :HTML,  File.expand_path("shell/html", __dir__)
+
+    # Add shell to initialize config values.
+    #
+    # ==== Configuration
+    # shell<Object>:: An instance of the shell to be used.
+    #
+    # ==== Examples
+    #
+    #   class MyScript < Bundler::Thor
+    #     argument :first, :type => :numeric
+    #   end
+    #
+    #   MyScript.new [1.0], { :foo => :bar }, :shell => Bundler::Thor::Shell::Basic.new
+    #
+    def initialize(args = [], options = {}, config = {})
+      super
+      self.shell = config[:shell]
+      shell.base ||= self if shell.respond_to?(:base)
+    end
+
+    # Holds the shell for the given Bundler::Thor instance. If no shell is given,
+    # it gets a default shell from Bundler::Thor::Base.shell.
+    def shell
+      @shell ||= Bundler::Thor::Base.shell.new
+    end
+
+    # Common methods that are delegated to the shell.
+    SHELL_DELEGATED_METHODS.each do |method|
+      module_eval <<-METHOD, __FILE__, __LINE__ + 1
+        def #{method}(*args,&block)
+          shell.#{method}(*args,&block)
+        end
+      METHOD
+    end
+
+    # Yields the given block with padding.
+    def with_padding
+      shell.padding += 1
+      yield
+    ensure
+      shell.padding -= 1
+    end
+
+  protected
+
+    # Allow shell to be shared between invocations.
+    #
+    def _shared_configuration #:nodoc:
+      super.merge!(shell: shell)
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/shell/basic.rb b/lib/bundler/vendor/thor/lib/thor/shell/basic.rb
new file mode 100644
index 0000000000..da02b94227
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/shell/basic.rb
@@ -0,0 +1,384 @@
+require_relative "column_printer"
+require_relative "table_printer"
+require_relative "wrapped_printer"
+
+class Bundler::Thor
+  module Shell
+    class Basic
+      attr_accessor :base
+      attr_reader   :padding
+
+      # Initialize base, mute and padding to nil.
+      #
+      def initialize #:nodoc:
+        @base = nil
+        @mute = false
+        @padding = 0
+        @always_force = false
+      end
+
+      # Mute everything that's inside given block
+      #
+      def mute
+        @mute = true
+        yield
+      ensure
+        @mute = false
+      end
+
+      # Check if base is muted
+      #
+      def mute?
+        @mute
+      end
+
+      # Sets the output padding, not allowing less than zero values.
+      #
+      def padding=(value)
+        @padding = [0, value].max
+      end
+
+      # Sets the output padding while executing a block and resets it.
+      #
+      def indent(count = 1)
+        orig_padding = padding
+        self.padding = padding + count
+        yield
+        self.padding = orig_padding
+      end
+
+      # Asks something to the user and receives a response.
+      #
+      # If a default value is specified it will be presented to the user
+      # and allows them to select that value with an empty response. This
+      # option is ignored when limited answers are supplied.
+      #
+      # If asked to limit the correct responses, you can pass in an
+      # array of acceptable answers.  If one of those is not supplied,
+      # they will be shown a message stating that one of those answers
+      # must be given and re-asked the question.
+      #
+      # If asking for sensitive information, the :echo option can be set
+      # to false to mask user input from $stdin.
+      #
+      # If the required input is a path, then set the path option to
+      # true. This will enable tab completion for file paths relative
+      # to the current working directory on systems that support
+      # Readline.
+      #
+      # ==== Example
+      #   ask("What is your name?")
+      #
+      #   ask("What is the planet furthest from the sun?", :default => "Neptune")
+      #
+      #   ask("What is your favorite Neopolitan flavor?", :limited_to => ["strawberry", "chocolate", "vanilla"])
+      #
+      #   ask("What is your password?", :echo => false)
+      #
+      #   ask("Where should the file be saved?", :path => true)
+      #
+      def ask(statement, *args)
+        options = args.last.is_a?(Hash) ? args.pop : {}
+        color = args.first
+
+        if options[:limited_to]
+          ask_filtered(statement, color, options)
+        else
+          ask_simply(statement, color, options)
+        end
+      end
+
+      # Say (print) something to the user. If the sentence ends with a whitespace
+      # or tab character, a new line is not appended (print + flush). Otherwise
+      # are passed straight to puts (behavior got from Highline).
+      #
+      # ==== Example
+      #   say("I know you knew that.")
+      #
+      def say(message = "", color = nil, force_new_line = (message.to_s !~ /( |\t)\Z/))
+        return if quiet?
+
+        buffer = prepare_message(message, *color)
+        buffer << "\n" if force_new_line && !message.to_s.end_with?("\n")
+
+        stdout.print(buffer)
+        stdout.flush
+      end
+
+      # Say (print) an error to the user. If the sentence ends with a whitespace
+      # or tab character, a new line is not appended (print + flush). Otherwise
+      # are passed straight to puts (behavior got from Highline).
+      #
+      # ==== Example
+      #   say_error("error: something went wrong")
+      #
+      def say_error(message = "", color = nil, force_new_line = (message.to_s !~ /( |\t)\Z/))
+        return if quiet?
+
+        buffer = prepare_message(message, *color)
+        buffer << "\n" if force_new_line && !message.to_s.end_with?("\n")
+
+        stderr.print(buffer)
+        stderr.flush
+      end
+
+      # Say a status with the given color and appends the message. Since this
+      # method is used frequently by actions, it allows nil or false to be given
+      # in log_status, avoiding the message from being shown. If a Symbol is
+      # given in log_status, it's used as the color.
+      #
+      def say_status(status, message, log_status = true)
+        return if quiet? || log_status == false
+        spaces = "  " * (padding + 1)
+        status = status.to_s.rjust(12)
+        margin = " " * status.length + spaces
+
+        color  = log_status.is_a?(Symbol) ? log_status : :green
+        status = set_color status, color, true if color
+
+        message = message.to_s.chomp.gsub(/(?<!\A)^/, margin)
+        buffer = "#{status}#{spaces}#{message}\n"
+
+        stdout.print(buffer)
+        stdout.flush
+      end
+
+      # Asks the user a question and returns true if the user replies "y" or
+      # "yes".
+      #
+      def yes?(statement, color = nil)
+        !!(ask(statement, color, add_to_history: false) =~ is?(:yes))
+      end
+
+      # Asks the user a question and returns true if the user replies "n" or
+      # "no".
+      #
+      def no?(statement, color = nil)
+        !!(ask(statement, color, add_to_history: false) =~ is?(:no))
+      end
+
+      # Prints values in columns
+      #
+      # ==== Parameters
+      # Array[String, String, ...]
+      #
+      def print_in_columns(array)
+        printer = ColumnPrinter.new(stdout)
+        printer.print(array)
+      end
+
+      # Prints a table.
+      #
+      # ==== Parameters
+      # Array[Array[String, String, ...]]
+      #
+      # ==== Options
+      # indent<Integer>:: Indent the first column by indent value.
+      # colwidth<Integer>:: Force the first column to colwidth spaces wide.
+      # borders<Boolean>:: Adds ascii borders.
+      #
+      def print_table(array, options = {}) # rubocop:disable Metrics/MethodLength
+        printer = TablePrinter.new(stdout, options)
+        printer.print(array)
+      end
+
+      # Prints a long string, word-wrapping the text to the current width of the
+      # terminal display. Ideal for printing heredocs.
+      #
+      # ==== Parameters
+      # String
+      #
+      # ==== Options
+      # indent<Integer>:: Indent each line of the printed paragraph by indent value.
+      #
+      def print_wrapped(message, options = {})
+        printer = WrappedPrinter.new(stdout, options)
+        printer.print(message)
+      end
+
+      # Deals with file collision and returns true if the file should be
+      # overwritten and false otherwise. If a block is given, it uses the block
+      # response as the content for the diff.
+      #
+      # ==== Parameters
+      # destination<String>:: the destination file to solve conflicts
+      # block<Proc>:: an optional block that returns the value to be used in diff and merge
+      #
+      def file_collision(destination)
+        return true if @always_force
+        options = block_given? ? "[Ynaqdhm]" : "[Ynaqh]"
+
+        loop do
+          answer = ask(
+            %[Overwrite #{destination}? (enter "h" for help) #{options}],
+            add_to_history: false
+          )
+
+          case answer
+          when nil
+            say ""
+            return true
+          when is?(:yes), is?(:force), ""
+            return true
+          when is?(:no), is?(:skip)
+            return false
+          when is?(:always)
+            return @always_force = true
+          when is?(:quit)
+            say "Aborting..."
+            raise SystemExit
+          when is?(:diff)
+            show_diff(destination, yield) if block_given?
+            say "Retrying..."
+          when is?(:merge)
+            if block_given? && !merge_tool.empty?
+              merge(destination, yield)
+              return nil
+            end
+
+            say "Please specify merge tool to `THOR_MERGE` env."
+          else
+            say file_collision_help(block_given?)
+          end
+        end
+      end
+
+      # Called if something goes wrong during the execution. This is used by Bundler::Thor
+      # internally and should not be used inside your scripts. If something went
+      # wrong, you can always raise an exception. If you raise a Bundler::Thor::Error, it
+      # will be rescued and wrapped in the method below.
+      #
+      def error(statement)
+        stderr.puts statement
+      end
+
+      # Apply color to the given string with optional bold. Disabled in the
+      # Bundler::Thor::Shell::Basic class.
+      #
+      def set_color(string, *) #:nodoc:
+        string
+      end
+
+    protected
+
+      def prepare_message(message, *color)
+        spaces = "  " * padding
+        spaces + set_color(message.to_s, *color)
+      end
+
+      def can_display_colors?
+        false
+      end
+
+      def lookup_color(color)
+        return color unless color.is_a?(Symbol)
+        self.class.const_get(color.to_s.upcase)
+      end
+
+      def stdout
+        $stdout
+      end
+
+      def stderr
+        $stderr
+      end
+
+      def is?(value) #:nodoc:
+        value = value.to_s
+
+        if value.size == 1
+          /\A#{value}\z/i
+        else
+          /\A(#{value}|#{value[0, 1]})\z/i
+        end
+      end
+
+      def file_collision_help(block_given) #:nodoc:
+        help = <<-HELP
+        Y - yes, overwrite
+        n - no, do not overwrite
+        a - all, overwrite this and all others
+        q - quit, abort
+        h - help, show this help
+        HELP
+        if block_given
+          help << <<-HELP
+        d - diff, show the differences between the old and the new
+        m - merge, run merge tool
+          HELP
+        end
+        help
+      end
+
+      def show_diff(destination, content) #:nodoc:
+        diff_cmd = ENV["THOR_DIFF"] || ENV["RAILS_DIFF"] || "diff -u"
+
+        require "tempfile"
+        Tempfile.open(File.basename(destination), File.dirname(destination), binmode: true) do |temp|
+          temp.write content
+          temp.rewind
+          system %(#{diff_cmd} "#{destination}" "#{temp.path}")
+        end
+      end
+
+      def quiet? #:nodoc:
+        mute? || (base && base.options[:quiet])
+      end
+
+      def unix?
+        Terminal.unix?
+      end
+
+      def ask_simply(statement, color, options)
+        default = options[:default]
+        message = [statement, ("(#{default})" if default), nil].uniq.join(" ")
+        message = prepare_message(message, *color)
+        result = Bundler::Thor::LineEditor.readline(message, options)
+
+        return unless result
+
+        result = result.strip
+
+        if default && result == ""
+          default
+        else
+          result
+        end
+      end
+
+      def ask_filtered(statement, color, options)
+        answer_set = options[:limited_to]
+        case_insensitive = options.fetch(:case_insensitive, false)
+        correct_answer = nil
+        until correct_answer
+          answers = answer_set.join(", ")
+          answer = ask_simply("#{statement} [#{answers}]", color, options)
+          correct_answer = answer_match(answer_set, answer, case_insensitive)
+          say("Your response must be one of: [#{answers}]. Please try again.") unless correct_answer
+        end
+        correct_answer
+      end
+
+      def answer_match(possibilities, answer, case_insensitive)
+        if case_insensitive
+          possibilities.detect{ |possibility| possibility.downcase == answer.downcase }
+        else
+          possibilities.detect{ |possibility| possibility == answer }
+        end
+      end
+
+      def merge(destination, content) #:nodoc:
+        require "tempfile"
+        Tempfile.open([File.basename(destination), File.extname(destination)], File.dirname(destination)) do |temp|
+          temp.write content
+          temp.rewind
+          system(merge_tool, temp.path, destination)
+        end
+      end
+
+      def merge_tool #:nodoc:
+        @merge_tool ||= ENV["THOR_MERGE"] || "git difftool --no-index"
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/shell/color.rb b/lib/bundler/vendor/thor/lib/thor/shell/color.rb
new file mode 100644
index 0000000000..5d708fadca
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/shell/color.rb
@@ -0,0 +1,112 @@
+require_relative "basic"
+
+class Bundler::Thor
+  module Shell
+    # Inherit from Bundler::Thor::Shell::Basic and add set_color behavior. Check
+    # Bundler::Thor::Shell::Basic to see all available methods.
+    #
+    class Color < Basic
+      # Embed in a String to clear all previous ANSI sequences.
+      CLEAR      = "\e[0m"
+      # The start of an ANSI bold sequence.
+      BOLD       = "\e[1m"
+
+      # Set the terminal's foreground ANSI color to black.
+      BLACK      = "\e[30m"
+      # Set the terminal's foreground ANSI color to red.
+      RED        = "\e[31m"
+      # Set the terminal's foreground ANSI color to green.
+      GREEN      = "\e[32m"
+      # Set the terminal's foreground ANSI color to yellow.
+      YELLOW     = "\e[33m"
+      # Set the terminal's foreground ANSI color to blue.
+      BLUE       = "\e[34m"
+      # Set the terminal's foreground ANSI color to magenta.
+      MAGENTA    = "\e[35m"
+      # Set the terminal's foreground ANSI color to cyan.
+      CYAN       = "\e[36m"
+      # Set the terminal's foreground ANSI color to white.
+      WHITE      = "\e[37m"
+
+      # Set the terminal's background ANSI color to black.
+      ON_BLACK   = "\e[40m"
+      # Set the terminal's background ANSI color to red.
+      ON_RED     = "\e[41m"
+      # Set the terminal's background ANSI color to green.
+      ON_GREEN   = "\e[42m"
+      # Set the terminal's background ANSI color to yellow.
+      ON_YELLOW  = "\e[43m"
+      # Set the terminal's background ANSI color to blue.
+      ON_BLUE    = "\e[44m"
+      # Set the terminal's background ANSI color to magenta.
+      ON_MAGENTA = "\e[45m"
+      # Set the terminal's background ANSI color to cyan.
+      ON_CYAN    = "\e[46m"
+      # Set the terminal's background ANSI color to white.
+      ON_WHITE   = "\e[47m"
+
+      # Set color by using a string or one of the defined constants. If a third
+      # option is set to true, it also adds bold to the string. This is based
+      # on Highline implementation and it automatically appends CLEAR to the end
+      # of the returned String.
+      #
+      # Pass foreground, background and bold options to this method as
+      # symbols.
+      #
+      # Example:
+      #
+      #   set_color "Hi!", :red, :on_white, :bold
+      #
+      # The available colors are:
+      #
+      #   :bold
+      #   :black
+      #   :red
+      #   :green
+      #   :yellow
+      #   :blue
+      #   :magenta
+      #   :cyan
+      #   :white
+      #   :on_black
+      #   :on_red
+      #   :on_green
+      #   :on_yellow
+      #   :on_blue
+      #   :on_magenta
+      #   :on_cyan
+      #   :on_white
+      def set_color(string, *colors)
+        if colors.compact.empty? || !can_display_colors?
+          string
+        elsif colors.all? { |color| color.is_a?(Symbol) || color.is_a?(String) }
+          ansi_colors = colors.map { |color| lookup_color(color) }
+          "#{ansi_colors.join}#{string}#{CLEAR}"
+        else
+          # The old API was `set_color(color, bold=boolean)`. We
+          # continue to support the old API because you should never
+          # break old APIs unnecessarily :P
+          foreground, bold = colors
+          foreground = self.class.const_get(foreground.to_s.upcase) if foreground.is_a?(Symbol)
+
+          bold       = bold ? BOLD : ""
+          "#{bold}#{foreground}#{string}#{CLEAR}"
+        end
+      end
+
+    protected
+
+      def can_display_colors?
+        are_colors_supported? && !are_colors_disabled?
+      end
+
+      def are_colors_supported?
+        stdout.tty? && ENV["TERM"] != "dumb"
+      end
+
+      def are_colors_disabled?
+        !ENV["NO_COLOR"].nil? && !ENV["NO_COLOR"].empty?
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/shell/column_printer.rb b/lib/bundler/vendor/thor/lib/thor/shell/column_printer.rb
new file mode 100644
index 0000000000..56a9e6181b
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/shell/column_printer.rb
@@ -0,0 +1,29 @@
+require_relative "terminal"
+
+class Bundler::Thor
+  module Shell
+    class ColumnPrinter
+      attr_reader :stdout, :options
+
+      def initialize(stdout, options = {})
+        @stdout = stdout
+        @options = options
+        @indent = options[:indent].to_i
+      end
+
+      def print(array)
+        return if array.empty?
+        colwidth = (array.map { |el| el.to_s.size }.max || 0) + 2
+        array.each_with_index do |value, index|
+          # Don't output trailing spaces when printing the last column
+          if ((((index + 1) % (Terminal.terminal_width / colwidth))).zero? && !index.zero?) || index + 1 == array.length
+            stdout.puts value
+          else
+            stdout.printf("%-#{colwidth}s", value)
+          end
+        end
+      end
+    end
+  end
+end
+
diff --git a/lib/bundler/vendor/thor/lib/thor/shell/html.rb b/lib/bundler/vendor/thor/lib/thor/shell/html.rb
new file mode 100644
index 0000000000..a0a8520e5c
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/shell/html.rb
@@ -0,0 +1,81 @@
+require_relative "basic"
+
+class Bundler::Thor
+  module Shell
+    # Inherit from Bundler::Thor::Shell::Basic and add set_color behavior. Check
+    # Bundler::Thor::Shell::Basic to see all available methods.
+    #
+    class HTML < Basic
+      # The start of an HTML bold sequence.
+      BOLD       = "font-weight: bold"
+
+      # Set the terminal's foreground HTML color to black.
+      BLACK      = "color: black"
+      # Set the terminal's foreground HTML color to red.
+      RED        = "color: red"
+      # Set the terminal's foreground HTML color to green.
+      GREEN      = "color: green"
+      # Set the terminal's foreground HTML color to yellow.
+      YELLOW     = "color: yellow"
+      # Set the terminal's foreground HTML color to blue.
+      BLUE       = "color: blue"
+      # Set the terminal's foreground HTML color to magenta.
+      MAGENTA    = "color: magenta"
+      # Set the terminal's foreground HTML color to cyan.
+      CYAN       = "color: cyan"
+      # Set the terminal's foreground HTML color to white.
+      WHITE      = "color: white"
+
+      # Set the terminal's background HTML color to black.
+      ON_BLACK   = "background-color: black"
+      # Set the terminal's background HTML color to red.
+      ON_RED     = "background-color: red"
+      # Set the terminal's background HTML color to green.
+      ON_GREEN   = "background-color: green"
+      # Set the terminal's background HTML color to yellow.
+      ON_YELLOW  = "background-color: yellow"
+      # Set the terminal's background HTML color to blue.
+      ON_BLUE    = "background-color: blue"
+      # Set the terminal's background HTML color to magenta.
+      ON_MAGENTA = "background-color: magenta"
+      # Set the terminal's background HTML color to cyan.
+      ON_CYAN    = "background-color: cyan"
+      # Set the terminal's background HTML color to white.
+      ON_WHITE   = "background-color: white"
+
+      # Set color by using a string or one of the defined constants. If a third
+      # option is set to true, it also adds bold to the string. This is based
+      # on Highline implementation and it automatically appends CLEAR to the end
+      # of the returned String.
+      #
+      def set_color(string, *colors)
+        if colors.all? { |color| color.is_a?(Symbol) || color.is_a?(String) }
+          html_colors = colors.map { |color| lookup_color(color) }
+          "<span style=\"#{html_colors.join('; ')};\">#{Bundler::Thor::Util.escape_html(string)}</span>"
+        else
+          color, bold = colors
+          html_color = self.class.const_get(color.to_s.upcase) if color.is_a?(Symbol)
+          styles = [html_color]
+          styles << BOLD if bold
+          "<span style=\"#{styles.join('; ')};\">#{Bundler::Thor::Util.escape_html(string)}</span>"
+        end
+      end
+
+      # Ask something to the user and receives a response.
+      #
+      # ==== Example
+      #   ask("What is your name?")
+      #
+      # TODO: Implement #ask for Bundler::Thor::Shell::HTML
+      def ask(statement, color = nil)
+        raise NotImplementedError, "Implement #ask for Bundler::Thor::Shell::HTML"
+      end
+
+    protected
+
+      def can_display_colors?
+        true
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/shell/table_printer.rb b/lib/bundler/vendor/thor/lib/thor/shell/table_printer.rb
new file mode 100644
index 0000000000..dee3614753
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/shell/table_printer.rb
@@ -0,0 +1,118 @@
+require_relative "column_printer"
+require_relative "terminal"
+
+class Bundler::Thor
+  module Shell
+    class TablePrinter < ColumnPrinter
+      BORDER_SEPARATOR = :separator
+
+      def initialize(stdout, options = {})
+        super
+        @formats = []
+        @maximas = []
+        @colwidth = options[:colwidth]
+        @truncate = options[:truncate] == true ? Terminal.terminal_width : options[:truncate]
+        @padding = 1
+      end
+
+      def print(array)
+        return if array.empty?
+
+        prepare(array)
+
+        print_border_separator if options[:borders]
+
+        array.each do |row|
+          if options[:borders] && row == BORDER_SEPARATOR
+            print_border_separator
+            next
+          end
+
+          sentence = "".dup
+
+          row.each_with_index do |column, index|
+            sentence << format_cell(column, row.size, index)
+          end
+
+          sentence = truncate(sentence)
+          sentence << "|" if options[:borders]
+          stdout.puts indentation + sentence
+
+        end
+        print_border_separator if options[:borders]
+      end
+
+    private
+
+      def prepare(array)
+        array = array.reject{|row| row == BORDER_SEPARATOR }
+
+        @formats << "%-#{@colwidth + 2}s".dup if @colwidth
+        start = @colwidth ? 1 : 0
+
+        colcount = array.max { |a, b| a.size <=> b.size }.size
+
+        start.upto(colcount - 1) do |index|
+          maxima = array.map { |row| row[index] ? row[index].to_s.size : 0 }.max
+
+          @maximas << maxima
+          @formats << if options[:borders]
+             "%-#{maxima}s".dup
+          elsif index == colcount - 1
+            # Don't output 2 trailing spaces when printing the last column
+            "%-s".dup
+          else
+            "%-#{maxima + 2}s".dup
+          end
+        end
+
+        @formats << "%s"
+      end
+
+      def format_cell(column, row_size, index)
+        maxima = @maximas[index]
+
+        f = if column.is_a?(Numeric)
+          if options[:borders]
+            # With borders we handle padding separately
+            "%#{maxima}s"
+          elsif index == row_size - 1
+            # Don't output 2 trailing spaces when printing the last column
+            "%#{maxima}s"
+          else
+            "%#{maxima}s  "
+          end
+        else
+          @formats[index]
+        end
+
+        cell = "".dup
+        cell << "|" + " " * @padding if options[:borders]
+        cell << f % column.to_s
+        cell << " " * @padding if options[:borders]
+        cell
+      end
+
+      def print_border_separator
+        separator = @maximas.map do |maxima|
+          "+" + "-" * (maxima + 2 * @padding)
+        end
+        stdout.puts indentation + separator.join + "+"
+      end
+
+      def truncate(string)
+        return string unless @truncate
+        chars = string.chars.to_a
+        if chars.length <= @truncate
+          chars.join
+        else
+          chars[0, @truncate - 3 - @indent].join + "..."
+        end
+      end
+
+      def indentation
+        " " * @indent
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/shell/terminal.rb b/lib/bundler/vendor/thor/lib/thor/shell/terminal.rb
new file mode 100644
index 0000000000..2c60684308
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/shell/terminal.rb
@@ -0,0 +1,42 @@
+class Bundler::Thor
+  module Shell
+    module Terminal
+      DEFAULT_TERMINAL_WIDTH = 80
+
+      class << self
+        # This code was copied from Rake, available under MIT-LICENSE
+        # Copyright (c) 2003, 2004 Jim Weirich
+        def terminal_width
+          result = if ENV["THOR_COLUMNS"]
+            ENV["THOR_COLUMNS"].to_i
+          else
+            unix? ? dynamic_width : DEFAULT_TERMINAL_WIDTH
+          end
+          result < 10 ? DEFAULT_TERMINAL_WIDTH : result
+        rescue
+          DEFAULT_TERMINAL_WIDTH
+        end
+
+        def unix?
+          RUBY_PLATFORM =~ /(aix|darwin|linux|(net|free|open)bsd|cygwin|solaris)/i
+        end
+
+      private
+
+        # Calculate the dynamic width of the terminal
+        def dynamic_width
+          @dynamic_width ||= (dynamic_width_stty.nonzero? || dynamic_width_tput)
+        end
+
+        def dynamic_width_stty
+          `stty size 2>/dev/null`.split[1].to_i
+        end
+
+        def dynamic_width_tput
+          `tput cols 2>/dev/null`.to_i
+        end
+
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/shell/wrapped_printer.rb b/lib/bundler/vendor/thor/lib/thor/shell/wrapped_printer.rb
new file mode 100644
index 0000000000..ba88e952db
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/shell/wrapped_printer.rb
@@ -0,0 +1,38 @@
+require_relative "column_printer"
+require_relative "terminal"
+
+class Bundler::Thor
+  module Shell
+    class WrappedPrinter < ColumnPrinter
+      def print(message)
+        width = Terminal.terminal_width - @indent
+        paras = message.split("\n\n")
+
+        paras.map! do |unwrapped|
+          words = unwrapped.split(" ")
+          counter = words.first.length
+          words.inject do |memo, word|
+            word = word.gsub(/\n\005/, "\n").gsub(/\005/, "\n")
+            counter = 0 if word.include? "\n"
+            if (counter + word.length + 1) < width
+              memo = "#{memo} #{word}"
+              counter += (word.length + 1)
+            else
+              memo = "#{memo}\n#{word}"
+              counter = word.length
+            end
+            memo
+          end
+        end.compact!
+
+        paras.each do |para|
+          para.split("\n").each do |line|
+            stdout.puts line.insert(0, " " * @indent)
+          end
+          stdout.puts unless para == paras.last
+        end
+      end
+    end
+  end
+end
+
diff --git a/lib/bundler/vendor/thor/lib/thor/util.rb b/lib/bundler/vendor/thor/lib/thor/util.rb
new file mode 100644
index 0000000000..cd8f9ece87
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/util.rb
@@ -0,0 +1,285 @@
+require "rbconfig"
+
+class Bundler::Thor
+  module Sandbox #:nodoc:
+  end
+
+  # This module holds several utilities:
+  #
+  # 1) Methods to convert thor namespaces to constants and vice-versa.
+  #
+  #   Bundler::Thor::Util.namespace_from_thor_class(Foo::Bar::Baz) #=> "foo:bar:baz"
+  #
+  # 2) Loading thor files and sandboxing:
+  #
+  #   Bundler::Thor::Util.load_thorfile("~/.thor/foo")
+  #
+  module Util
+    class << self
+      # Receives a namespace and search for it in the Bundler::Thor::Base subclasses.
+      #
+      # ==== Parameters
+      # namespace<String>:: The namespace to search for.
+      #
+      def find_by_namespace(namespace)
+        namespace = "default#{namespace}" if namespace.empty? || namespace =~ /^:/
+        Bundler::Thor::Base.subclasses.detect { |klass| klass.namespace == namespace }
+      end
+
+      # Receives a constant and converts it to a Bundler::Thor namespace. Since Bundler::Thor
+      # commands can be added to a sandbox, this method is also responsible for
+      # removing the sandbox namespace.
+      #
+      # This method should not be used in general because it's used to deal with
+      # older versions of Bundler::Thor. On current versions, if you need to get the
+      # namespace from a class, just call namespace on it.
+      #
+      # ==== Parameters
+      # constant<Object>:: The constant to be converted to the thor path.
+      #
+      # ==== Returns
+      # String:: If we receive Foo::Bar::Baz it returns "foo:bar:baz"
+      #
+      def namespace_from_thor_class(constant)
+        constant = constant.to_s.gsub(/^Bundler::Thor::Sandbox::/, "")
+        constant = snake_case(constant).squeeze(":")
+        constant
+      end
+
+      # Given the contents, evaluate it inside the sandbox and returns the
+      # namespaces defined in the sandbox.
+      #
+      # ==== Parameters
+      # contents<String>
+      #
+      # ==== Returns
+      # Array[Object]
+      #
+      def namespaces_in_content(contents, file = __FILE__)
+        old_constants = Bundler::Thor::Base.subclasses.dup
+        Bundler::Thor::Base.subclasses.clear
+
+        load_thorfile(file, contents)
+
+        new_constants = Bundler::Thor::Base.subclasses.dup
+        Bundler::Thor::Base.subclasses.replace(old_constants)
+
+        new_constants.map!(&:namespace)
+        new_constants.compact!
+        new_constants
+      end
+
+      # Returns the thor classes declared inside the given class.
+      #
+      def thor_classes_in(klass)
+        stringfied_constants = klass.constants.map(&:to_s)
+        Bundler::Thor::Base.subclasses.select do |subclass|
+          next unless subclass.name
+          stringfied_constants.include?(subclass.name.gsub("#{klass.name}::", ""))
+        end
+      end
+
+      # Receives a string and convert it to snake case. SnakeCase returns snake_case.
+      #
+      # ==== Parameters
+      # String
+      #
+      # ==== Returns
+      # String
+      #
+      def snake_case(str)
+        return str.downcase if str =~ /^[A-Z_]+$/
+        str.gsub(/\B[A-Z]/, '_\&').squeeze("_") =~ /_*(.*)/
+        Regexp.last_match(-1).downcase
+      end
+
+      # Receives a string and convert it to camel case. camel_case returns CamelCase.
+      #
+      # ==== Parameters
+      # String
+      #
+      # ==== Returns
+      # String
+      #
+      def camel_case(str)
+        return str if str !~ /_/ && str =~ /[A-Z]+.*/
+        str.split("_").map(&:capitalize).join
+      end
+
+      # Receives a namespace and tries to retrieve a Bundler::Thor or Bundler::Thor::Group class
+      # from it. It first searches for a class using the all the given namespace,
+      # if it's not found, removes the highest entry and searches for the class
+      # again. If found, returns the highest entry as the class name.
+      #
+      # ==== Examples
+      #
+      #   class Foo::Bar < Bundler::Thor
+      #     def baz
+      #     end
+      #   end
+      #
+      #   class Baz::Foo < Bundler::Thor::Group
+      #   end
+      #
+      #   Bundler::Thor::Util.namespace_to_thor_class("foo:bar")     #=> Foo::Bar, nil # will invoke default command
+      #   Bundler::Thor::Util.namespace_to_thor_class("baz:foo")     #=> Baz::Foo, nil
+      #   Bundler::Thor::Util.namespace_to_thor_class("foo:bar:baz") #=> Foo::Bar, "baz"
+      #
+      # ==== Parameters
+      # namespace<String>
+      #
+      def find_class_and_command_by_namespace(namespace, fallback = true)
+        if namespace.include?(":") # look for a namespaced command
+          *pieces, command  = namespace.split(":")
+          namespace = pieces.join(":")
+          namespace = "default" if namespace.empty?
+          klass = Bundler::Thor::Base.subclasses.detect { |thor| thor.namespace == namespace && thor.command_exists?(command) }
+        end
+        unless klass # look for a Bundler::Thor::Group with the right name
+          klass = Bundler::Thor::Util.find_by_namespace(namespace)
+          command = nil
+        end
+        if !klass && fallback # try a command in the default namespace
+          command = namespace
+          klass   = Bundler::Thor::Util.find_by_namespace("")
+        end
+        [klass, command]
+      end
+      alias_method :find_class_and_task_by_namespace, :find_class_and_command_by_namespace
+
+      # Receives a path and load the thor file in the path. The file is evaluated
+      # inside the sandbox to avoid namespacing conflicts.
+      #
+      def load_thorfile(path, content = nil, debug = false)
+        content ||= File.read(path)
+
+        begin
+          Bundler::Thor::Sandbox.class_eval(content, path)
+        rescue StandardError => e
+          $stderr.puts("WARNING: unable to load thorfile #{path.inspect}: #{e.message}")
+          if debug
+            $stderr.puts(*e.backtrace)
+          else
+            $stderr.puts(e.backtrace.first)
+          end
+        end
+      end
+
+      def user_home
+        @@user_home ||= if ENV["HOME"]
+          ENV["HOME"]
+        elsif ENV["USERPROFILE"]
+          ENV["USERPROFILE"]
+        elsif ENV["HOMEDRIVE"] && ENV["HOMEPATH"]
+          File.join(ENV["HOMEDRIVE"], ENV["HOMEPATH"])
+        elsif ENV["APPDATA"]
+          ENV["APPDATA"]
+        else
+          begin
+            File.expand_path("~")
+          rescue
+            if File::ALT_SEPARATOR
+              "C:/"
+            else
+              "/"
+            end
+          end
+        end
+      end
+
+      # Returns the root where thor files are located, depending on the OS.
+      #
+      def thor_root
+        File.join(user_home, ".thor").tr("\\", "/")
+      end
+
+      # Returns the files in the thor root. On Windows thor_root will be something
+      # like this:
+      #
+      #   C:\Documents and Settings\james\.thor
+      #
+      # If we don't #gsub the \ character, Dir.glob will fail.
+      #
+      def thor_root_glob
+        files = Dir["#{escape_globs(thor_root)}/*"]
+
+        files.map! do |file|
+          File.directory?(file) ? File.join(file, "main.thor") : file
+        end
+      end
+
+      # Where to look for Bundler::Thor files.
+      #
+      def globs_for(path)
+        path = escape_globs(path)
+        ["#{path}/Thorfile", "#{path}/*.thor", "#{path}/tasks/*.thor", "#{path}/lib/tasks/**/*.thor"]
+      end
+
+      # Return the path to the ruby interpreter taking into account multiple
+      # installations and windows extensions.
+      #
+      def ruby_command
+        @ruby_command ||= begin
+          ruby_name = RbConfig::CONFIG["ruby_install_name"]
+          ruby = File.join(RbConfig::CONFIG["bindir"], ruby_name)
+          ruby << RbConfig::CONFIG["EXEEXT"]
+
+          # avoid using different name than ruby (on platforms supporting links)
+          if ruby_name != "ruby" && File.respond_to?(:readlink)
+            begin
+              alternate_ruby = File.join(RbConfig::CONFIG["bindir"], "ruby")
+              alternate_ruby << RbConfig::CONFIG["EXEEXT"]
+
+              # ruby is a symlink
+              if File.symlink? alternate_ruby
+                linked_ruby = File.readlink alternate_ruby
+
+                # symlink points to 'ruby_install_name'
+                ruby = alternate_ruby if linked_ruby == ruby_name || linked_ruby == ruby
+              end
+            rescue NotImplementedError # rubocop:disable Lint/HandleExceptions
+              # just ignore on windows
+            end
+          end
+
+          # escape string in case path to ruby executable contain spaces.
+          ruby.sub!(/.*\s.*/m, '"\&"')
+          ruby
+        end
+      end
+
+      # Returns a string that has had any glob characters escaped.
+      # The glob characters are `* ? { } [ ]`.
+      #
+      # ==== Examples
+      #
+      #   Bundler::Thor::Util.escape_globs('[apps]')   # => '\[apps\]'
+      #
+      # ==== Parameters
+      # String
+      #
+      # ==== Returns
+      # String
+      #
+      def escape_globs(path)
+        path.to_s.gsub(/[*?{}\[\]]/, '\\\\\\&')
+      end
+
+      # Returns a string that has had any HTML characters escaped.
+      #
+      # ==== Examples
+      #
+      #   Bundler::Thor::Util.escape_html('<div>')   # => "&lt;div&gt;"
+      #
+      # ==== Parameters
+      # String
+      #
+      # ==== Returns
+      # String
+      #
+      def escape_html(string)
+        CGI.escapeHTML(string)
+      end
+    end
+  end
+end
diff --git a/lib/bundler/vendor/thor/lib/thor/version.rb b/lib/bundler/vendor/thor/lib/thor/version.rb
new file mode 100644
index 0000000000..5474a2f71b
--- /dev/null
+++ b/lib/bundler/vendor/thor/lib/thor/version.rb
@@ -0,0 +1,3 @@
+class Bundler::Thor
+  VERSION = "1.4.0"
+end
diff --git a/lib/bundler/vendor/tsort/lib/tsort.rb b/lib/bundler/vendor/tsort/lib/tsort.rb
new file mode 100644
index 0000000000..cf8731f760
--- /dev/null
+++ b/lib/bundler/vendor/tsort/lib/tsort.rb
@@ -0,0 +1,455 @@
+# frozen_string_literal: true
+
+#--
+# tsort.rb - provides a module for topological sorting and strongly connected components.
+#++
+#
+
+#
+# Bundler::TSort implements topological sorting using Tarjan's algorithm for
+# strongly connected components.
+#
+# Bundler::TSort is designed to be able to be used with any object which can be
+# interpreted as a directed graph.
+#
+# Bundler::TSort requires two methods to interpret an object as a graph,
+# tsort_each_node and tsort_each_child.
+#
+# * tsort_each_node is used to iterate for all nodes over a graph.
+# * tsort_each_child is used to iterate for child nodes of a given node.
+#
+# The equality of nodes are defined by eql? and hash since
+# Bundler::TSort uses Hash internally.
+#
+# == A Simple Example
+#
+# The following example demonstrates how to mix the Bundler::TSort module into an
+# existing class (in this case, Hash). Here, we're treating each key in
+# the hash as a node in the graph, and so we simply alias the required
+# #tsort_each_node method to Hash's #each_key method. For each key in the
+# hash, the associated value is an array of the node's child nodes. This
+# choice in turn leads to our implementation of the required #tsort_each_child
+# method, which fetches the array of child nodes and then iterates over that
+# array using the user-supplied block.
+#
+#   require 'bundler/vendor/tsort/lib/tsort'
+#
+#   class Hash
+#     include Bundler::TSort
+#     alias tsort_each_node each_key
+#     def tsort_each_child(node, &block)
+#       fetch(node).each(&block)
+#     end
+#   end
+#
+#   {1=>[2, 3], 2=>[3], 3=>[], 4=>[]}.tsort
+#   #=> [3, 2, 1, 4]
+#
+#   {1=>[2], 2=>[3, 4], 3=>[2], 4=>[]}.strongly_connected_components
+#   #=> [[4], [2, 3], [1]]
+#
+# == A More Realistic Example
+#
+# A very simple `make' like tool can be implemented as follows:
+#
+#   require 'bundler/vendor/tsort/lib/tsort'
+#
+#   class Make
+#     def initialize
+#       @dep = {}
+#       @dep.default = []
+#     end
+#
+#     def rule(outputs, inputs=[], &block)
+#       triple = [outputs, inputs, block]
+#       outputs.each {|f| @dep[f] = [triple]}
+#       @dep[triple] = inputs
+#     end
+#
+#     def build(target)
+#       each_strongly_connected_component_from(target) {|ns|
+#         if ns.length != 1
+#           fs = ns.delete_if {|n| Array === n}
+#           raise Bundler::TSort::Cyclic.new("cyclic dependencies: #{fs.join ', '}")
+#         end
+#         n = ns.first
+#         if Array === n
+#           outputs, inputs, block = n
+#           inputs_time = inputs.map {|f| File.mtime f}.max
+#           begin
+#             outputs_time = outputs.map {|f| File.mtime f}.min
+#           rescue Errno::ENOENT
+#             outputs_time = nil
+#           end
+#           if outputs_time == nil ||
+#              inputs_time != nil && outputs_time <= inputs_time
+#             sleep 1 if inputs_time != nil && inputs_time.to_i == Time.now.to_i
+#             block.call
+#           end
+#         end
+#       }
+#     end
+#
+#     def tsort_each_child(node, &block)
+#       @dep[node].each(&block)
+#     end
+#     include Bundler::TSort
+#   end
+#
+#   def command(arg)
+#     print arg, "\n"
+#     system arg
+#   end
+#
+#   m = Make.new
+#   m.rule(%w[t1]) { command 'date > t1' }
+#   m.rule(%w[t2]) { command 'date > t2' }
+#   m.rule(%w[t3]) { command 'date > t3' }
+#   m.rule(%w[t4], %w[t1 t3]) { command 'cat t1 t3 > t4' }
+#   m.rule(%w[t5], %w[t4 t2]) { command 'cat t4 t2 > t5' }
+#   m.build('t5')
+#
+# == Bugs
+#
+# * 'tsort.rb' is wrong name because this library uses
+#   Tarjan's algorithm for strongly connected components.
+#   Although 'strongly_connected_components.rb' is correct but too long.
+#
+# == References
+#
+# R. E. Tarjan, "Depth First Search and Linear Graph Algorithms",
+# <em>SIAM Journal on Computing</em>, Vol. 1, No. 2, pp. 146-160, June 1972.
+#
+
+module Bundler::TSort
+
+  VERSION = "0.2.0"
+
+  class Cyclic < StandardError
+  end
+
+  # Returns a topologically sorted array of nodes.
+  # The array is sorted from children to parents, i.e.
+  # the first element has no child and the last node has no parent.
+  #
+  # If there is a cycle, Bundler::TSort::Cyclic is raised.
+  #
+  #   class G
+  #     include Bundler::TSort
+  #     def initialize(g)
+  #       @g = g
+  #     end
+  #     def tsort_each_child(n, &b) @g[n].each(&b) end
+  #     def tsort_each_node(&b) @g.each_key(&b) end
+  #   end
+  #
+  #   graph = G.new({1=>[2, 3], 2=>[4], 3=>[2, 4], 4=>[]})
+  #   p graph.tsort #=> [4, 2, 3, 1]
+  #
+  #   graph = G.new({1=>[2], 2=>[3, 4], 3=>[2], 4=>[]})
+  #   p graph.tsort # raises Bundler::TSort::Cyclic
+  #
+  def tsort
+    each_node = method(:tsort_each_node)
+    each_child = method(:tsort_each_child)
+    Bundler::TSort.tsort(each_node, each_child)
+  end
+
+  # Returns a topologically sorted array of nodes.
+  # The array is sorted from children to parents, i.e.
+  # the first element has no child and the last node has no parent.
+  #
+  # The graph is represented by _each_node_ and _each_child_.
+  # _each_node_ should have +call+ method which yields for each node in the graph.
+  # _each_child_ should have +call+ method which takes a node argument and yields for each child node.
+  #
+  # If there is a cycle, Bundler::TSort::Cyclic is raised.
+  #
+  #   g = {1=>[2, 3], 2=>[4], 3=>[2, 4], 4=>[]}
+  #   each_node = lambda {|&b| g.each_key(&b) }
+  #   each_child = lambda {|n, &b| g[n].each(&b) }
+  #   p Bundler::TSort.tsort(each_node, each_child) #=> [4, 2, 3, 1]
+  #
+  #   g = {1=>[2], 2=>[3, 4], 3=>[2], 4=>[]}
+  #   each_node = lambda {|&b| g.each_key(&b) }
+  #   each_child = lambda {|n, &b| g[n].each(&b) }
+  #   p Bundler::TSort.tsort(each_node, each_child) # raises Bundler::TSort::Cyclic
+  #
+  def self.tsort(each_node, each_child)
+    tsort_each(each_node, each_child).to_a
+  end
+
+  # The iterator version of the #tsort method.
+  # <tt><em>obj</em>.tsort_each</tt> is similar to <tt><em>obj</em>.tsort.each</tt>, but
+  # modification of _obj_ during the iteration may lead to unexpected results.
+  #
+  # #tsort_each returns +nil+.
+  # If there is a cycle, Bundler::TSort::Cyclic is raised.
+  #
+  #   class G
+  #     include Bundler::TSort
+  #     def initialize(g)
+  #       @g = g
+  #     end
+  #     def tsort_each_child(n, &b) @g[n].each(&b) end
+  #     def tsort_each_node(&b) @g.each_key(&b) end
+  #   end
+  #
+  #   graph = G.new({1=>[2, 3], 2=>[4], 3=>[2, 4], 4=>[]})
+  #   graph.tsort_each {|n| p n }
+  #   #=> 4
+  #   #   2
+  #   #   3
+  #   #   1
+  #
+  def tsort_each(&block) # :yields: node
+    each_node = method(:tsort_each_node)
+    each_child = method(:tsort_each_child)
+    Bundler::TSort.tsort_each(each_node, each_child, &block)
+  end
+
+  # The iterator version of the Bundler::TSort.tsort method.
+  #
+  # The graph is represented by _each_node_ and _each_child_.
+  # _each_node_ should have +call+ method which yields for each node in the graph.
+  # _each_child_ should have +call+ method which takes a node argument and yields for each child node.
+  #
+  #   g = {1=>[2, 3], 2=>[4], 3=>[2, 4], 4=>[]}
+  #   each_node = lambda {|&b| g.each_key(&b) }
+  #   each_child = lambda {|n, &b| g[n].each(&b) }
+  #   Bundler::TSort.tsort_each(each_node, each_child) {|n| p n }
+  #   #=> 4
+  #   #   2
+  #   #   3
+  #   #   1
+  #
+  def self.tsort_each(each_node, each_child) # :yields: node
+    return to_enum(__method__, each_node, each_child) unless block_given?
+
+    each_strongly_connected_component(each_node, each_child) {|component|
+      if component.size == 1
+        yield component.first
+      else
+        raise Cyclic.new("topological sort failed: #{component.inspect}")
+      end
+    }
+  end
+
+  # Returns strongly connected components as an array of arrays of nodes.
+  # The array is sorted from children to parents.
+  # Each elements of the array represents a strongly connected component.
+  #
+  #   class G
+  #     include Bundler::TSort
+  #     def initialize(g)
+  #       @g = g
+  #     end
+  #     def tsort_each_child(n, &b) @g[n].each(&b) end
+  #     def tsort_each_node(&b) @g.each_key(&b) end
+  #   end
+  #
+  #   graph = G.new({1=>[2, 3], 2=>[4], 3=>[2, 4], 4=>[]})
+  #   p graph.strongly_connected_components #=> [[4], [2], [3], [1]]
+  #
+  #   graph = G.new({1=>[2], 2=>[3, 4], 3=>[2], 4=>[]})
+  #   p graph.strongly_connected_components #=> [[4], [2, 3], [1]]
+  #
+  def strongly_connected_components
+    each_node = method(:tsort_each_node)
+    each_child = method(:tsort_each_child)
+    Bundler::TSort.strongly_connected_components(each_node, each_child)
+  end
+
+  # Returns strongly connected components as an array of arrays of nodes.
+  # The array is sorted from children to parents.
+  # Each elements of the array represents a strongly connected component.
+  #
+  # The graph is represented by _each_node_ and _each_child_.
+  # _each_node_ should have +call+ method which yields for each node in the graph.
+  # _each_child_ should have +call+ method which takes a node argument and yields for each child node.
+  #
+  #   g = {1=>[2, 3], 2=>[4], 3=>[2, 4], 4=>[]}
+  #   each_node = lambda {|&b| g.each_key(&b) }
+  #   each_child = lambda {|n, &b| g[n].each(&b) }
+  #   p Bundler::TSort.strongly_connected_components(each_node, each_child)
+  #   #=> [[4], [2], [3], [1]]
+  #
+  #   g = {1=>[2], 2=>[3, 4], 3=>[2], 4=>[]}
+  #   each_node = lambda {|&b| g.each_key(&b) }
+  #   each_child = lambda {|n, &b| g[n].each(&b) }
+  #   p Bundler::TSort.strongly_connected_components(each_node, each_child)
+  #   #=> [[4], [2, 3], [1]]
+  #
+  def self.strongly_connected_components(each_node, each_child)
+    each_strongly_connected_component(each_node, each_child).to_a
+  end
+
+  # The iterator version of the #strongly_connected_components method.
+  # <tt><em>obj</em>.each_strongly_connected_component</tt> is similar to
+  # <tt><em>obj</em>.strongly_connected_components.each</tt>, but
+  # modification of _obj_ during the iteration may lead to unexpected results.
+  #
+  # #each_strongly_connected_component returns +nil+.
+  #
+  #   class G
+  #     include Bundler::TSort
+  #     def initialize(g)
+  #       @g = g
+  #     end
+  #     def tsort_each_child(n, &b) @g[n].each(&b) end
+  #     def tsort_each_node(&b) @g.each_key(&b) end
+  #   end
+  #
+  #   graph = G.new({1=>[2, 3], 2=>[4], 3=>[2, 4], 4=>[]})
+  #   graph.each_strongly_connected_component {|scc| p scc }
+  #   #=> [4]
+  #   #   [2]
+  #   #   [3]
+  #   #   [1]
+  #
+  #   graph = G.new({1=>[2], 2=>[3, 4], 3=>[2], 4=>[]})
+  #   graph.each_strongly_connected_component {|scc| p scc }
+  #   #=> [4]
+  #   #   [2, 3]
+  #   #   [1]
+  #
+  def each_strongly_connected_component(&block) # :yields: nodes
+    each_node = method(:tsort_each_node)
+    each_child = method(:tsort_each_child)
+    Bundler::TSort.each_strongly_connected_component(each_node, each_child, &block)
+  end
+
+  # The iterator version of the Bundler::TSort.strongly_connected_components method.
+  #
+  # The graph is represented by _each_node_ and _each_child_.
+  # _each_node_ should have +call+ method which yields for each node in the graph.
+  # _each_child_ should have +call+ method which takes a node argument and yields for each child node.
+  #
+  #   g = {1=>[2, 3], 2=>[4], 3=>[2, 4], 4=>[]}
+  #   each_node = lambda {|&b| g.each_key(&b) }
+  #   each_child = lambda {|n, &b| g[n].each(&b) }
+  #   Bundler::TSort.each_strongly_connected_component(each_node, each_child) {|scc| p scc }
+  #   #=> [4]
+  #   #   [2]
+  #   #   [3]
+  #   #   [1]
+  #
+  #   g = {1=>[2], 2=>[3, 4], 3=>[2], 4=>[]}
+  #   each_node = lambda {|&b| g.each_key(&b) }
+  #   each_child = lambda {|n, &b| g[n].each(&b) }
+  #   Bundler::TSort.each_strongly_connected_component(each_node, each_child) {|scc| p scc }
+  #   #=> [4]
+  #   #   [2, 3]
+  #   #   [1]
+  #
+  def self.each_strongly_connected_component(each_node, each_child) # :yields: nodes
+    return to_enum(__method__, each_node, each_child) unless block_given?
+
+    id_map = {}
+    stack = []
+    each_node.call {|node|
+      unless id_map.include? node
+        each_strongly_connected_component_from(node, each_child, id_map, stack) {|c|
+          yield c
+        }
+      end
+    }
+    nil
+  end
+
+  # Iterates over strongly connected component in the subgraph reachable from
+  # _node_.
+  #
+  # Return value is unspecified.
+  #
+  # #each_strongly_connected_component_from doesn't call #tsort_each_node.
+  #
+  #   class G
+  #     include Bundler::TSort
+  #     def initialize(g)
+  #       @g = g
+  #     end
+  #     def tsort_each_child(n, &b) @g[n].each(&b) end
+  #     def tsort_each_node(&b) @g.each_key(&b) end
+  #   end
+  #
+  #   graph = G.new({1=>[2, 3], 2=>[4], 3=>[2, 4], 4=>[]})
+  #   graph.each_strongly_connected_component_from(2) {|scc| p scc }
+  #   #=> [4]
+  #   #   [2]
+  #
+  #   graph = G.new({1=>[2], 2=>[3, 4], 3=>[2], 4=>[]})
+  #   graph.each_strongly_connected_component_from(2) {|scc| p scc }
+  #   #=> [4]
+  #   #   [2, 3]
+  #
+  def each_strongly_connected_component_from(node, id_map={}, stack=[], &block) # :yields: nodes
+    Bundler::TSort.each_strongly_connected_component_from(node, method(:tsort_each_child), id_map, stack, &block)
+  end
+
+  # Iterates over strongly connected components in a graph.
+  # The graph is represented by _node_ and _each_child_.
+  #
+  # _node_ is the first node.
+  # _each_child_ should have +call+ method which takes a node argument
+  # and yields for each child node.
+  #
+  # Return value is unspecified.
+  #
+  # #Bundler::TSort.each_strongly_connected_component_from is a class method and
+  # it doesn't need a class to represent a graph which includes Bundler::TSort.
+  #
+  #   graph = {1=>[2], 2=>[3, 4], 3=>[2], 4=>[]}
+  #   each_child = lambda {|n, &b| graph[n].each(&b) }
+  #   Bundler::TSort.each_strongly_connected_component_from(1, each_child) {|scc|
+  #     p scc
+  #   }
+  #   #=> [4]
+  #   #   [2, 3]
+  #   #   [1]
+  #
+  def self.each_strongly_connected_component_from(node, each_child, id_map={}, stack=[]) # :yields: nodes
+    return to_enum(__method__, node, each_child, id_map, stack) unless block_given?
+
+    minimum_id = node_id = id_map[node] = id_map.size
+    stack_length = stack.length
+    stack << node
+
+    each_child.call(node) {|child|
+      if id_map.include? child
+        child_id = id_map[child]
+        minimum_id = child_id if child_id && child_id < minimum_id
+      else
+        sub_minimum_id =
+          each_strongly_connected_component_from(child, each_child, id_map, stack) {|c|
+            yield c
+          }
+        minimum_id = sub_minimum_id if sub_minimum_id < minimum_id
+      end
+    }
+
+    if node_id == minimum_id
+      component = stack.slice!(stack_length .. -1)
+      component.each {|n| id_map[n] = nil}
+      yield component
+    end
+
+    minimum_id
+  end
+
+  # Should be implemented by a extended class.
+  #
+  # #tsort_each_node is used to iterate for all nodes over a graph.
+  #
+  def tsort_each_node # :yields: node
+    raise NotImplementedError.new
+  end
+
+  # Should be implemented by a extended class.
+  #
+  # #tsort_each_child is used to iterate for child nodes of _node_.
+  #
+  def tsort_each_child(node) # :yields: child
+    raise NotImplementedError.new
+  end
+end
diff --git a/lib/bundler/vendor/uri/lib/uri.rb b/lib/bundler/vendor/uri/lib/uri.rb
new file mode 100644
index 0000000000..57b380c480
--- /dev/null
+++ b/lib/bundler/vendor/uri/lib/uri.rb
@@ -0,0 +1,104 @@
+# frozen_string_literal: false
+# Bundler::URI is a module providing classes to handle Uniform Resource Identifiers
+# (RFC2396[https://www.rfc-editor.org/rfc/rfc2396]).
+#
+# == Features
+#
+# * Uniform way of handling URIs.
+# * Flexibility to introduce custom Bundler::URI schemes.
+# * Flexibility to have an alternate Bundler::URI::Parser (or just different patterns
+#   and regexp's).
+#
+# == Basic example
+#
+#   require 'bundler/vendor/uri/lib/uri'
+#
+#   uri = Bundler::URI("http://foo.com/posts?id=30&limit=5#time=1305298413")
+#   #=> #<Bundler::URI::HTTP http://foo.com/posts?id=30&limit=5#time=1305298413>
+#
+#   uri.scheme    #=> "http"
+#   uri.host      #=> "foo.com"
+#   uri.path      #=> "/posts"
+#   uri.query     #=> "id=30&limit=5"
+#   uri.fragment  #=> "time=1305298413"
+#
+#   uri.to_s      #=> "http://foo.com/posts?id=30&limit=5#time=1305298413"
+#
+# == Adding custom URIs
+#
+#   module Bundler::URI
+#     class RSYNC < Generic
+#       DEFAULT_PORT = 873
+#     end
+#     register_scheme 'RSYNC', RSYNC
+#   end
+#   #=> Bundler::URI::RSYNC
+#
+#   Bundler::URI.scheme_list
+#   #=> {"FILE"=>Bundler::URI::File, "FTP"=>Bundler::URI::FTP, "HTTP"=>Bundler::URI::HTTP,
+#   #    "HTTPS"=>Bundler::URI::HTTPS, "LDAP"=>Bundler::URI::LDAP, "LDAPS"=>Bundler::URI::LDAPS,
+#   #    "MAILTO"=>Bundler::URI::MailTo, "RSYNC"=>Bundler::URI::RSYNC}
+#
+#   uri = Bundler::URI("rsync://rsync.foo.com")
+#   #=> #<Bundler::URI::RSYNC rsync://rsync.foo.com>
+#
+# == RFC References
+#
+# A good place to view an RFC spec is http://www.ietf.org/rfc.html.
+#
+# Here is a list of all related RFC's:
+# - RFC822[https://www.rfc-editor.org/rfc/rfc822]
+# - RFC1738[https://www.rfc-editor.org/rfc/rfc1738]
+# - RFC2255[https://www.rfc-editor.org/rfc/rfc2255]
+# - RFC2368[https://www.rfc-editor.org/rfc/rfc2368]
+# - RFC2373[https://www.rfc-editor.org/rfc/rfc2373]
+# - RFC2396[https://www.rfc-editor.org/rfc/rfc2396]
+# - RFC2732[https://www.rfc-editor.org/rfc/rfc2732]
+# - RFC3986[https://www.rfc-editor.org/rfc/rfc3986]
+#
+# == Class tree
+#
+# - Bundler::URI::Generic (in uri/generic.rb)
+#   - Bundler::URI::File - (in uri/file.rb)
+#   - Bundler::URI::FTP - (in uri/ftp.rb)
+#   - Bundler::URI::HTTP - (in uri/http.rb)
+#     - Bundler::URI::HTTPS - (in uri/https.rb)
+#   - Bundler::URI::LDAP - (in uri/ldap.rb)
+#     - Bundler::URI::LDAPS - (in uri/ldaps.rb)
+#   - Bundler::URI::MailTo - (in uri/mailto.rb)
+# - Bundler::URI::Parser - (in uri/common.rb)
+# - Bundler::URI::REGEXP - (in uri/common.rb)
+#   - Bundler::URI::REGEXP::PATTERN - (in uri/common.rb)
+# - Bundler::URI::Util - (in uri/common.rb)
+# - Bundler::URI::Error - (in uri/common.rb)
+#   - Bundler::URI::InvalidURIError - (in uri/common.rb)
+#   - Bundler::URI::InvalidComponentError - (in uri/common.rb)
+#   - Bundler::URI::BadURIError - (in uri/common.rb)
+#
+# == Copyright Info
+#
+# Author:: Akira Yamada <akira@ruby-lang.org>
+# Documentation::
+#   Akira Yamada <akira@ruby-lang.org>
+#   Dmitry V. Sabanin <sdmitry@lrn.ru>
+#   Vincent Batts <vbatts@hashbangbash.com>
+# License::
+#  Copyright (c) 2001 akira yamada <akira@ruby-lang.org>
+#  You can redistribute it and/or modify it under the same term as Ruby.
+#
+
+module Bundler::URI
+end
+
+require_relative 'uri/version'
+require_relative 'uri/common'
+require_relative 'uri/generic'
+require_relative 'uri/file'
+require_relative 'uri/ftp'
+require_relative 'uri/http'
+require_relative 'uri/https'
+require_relative 'uri/ldap'
+require_relative 'uri/ldaps'
+require_relative 'uri/mailto'
+require_relative 'uri/ws'
+require_relative 'uri/wss'
diff --git a/lib/bundler/vendor/uri/lib/uri/common.rb b/lib/bundler/vendor/uri/lib/uri/common.rb
new file mode 100644
index 0000000000..38339119c5
--- /dev/null
+++ b/lib/bundler/vendor/uri/lib/uri/common.rb
@@ -0,0 +1,922 @@
+# frozen_string_literal: true
+#--
+# = uri/common.rb
+#
+# Author:: Akira Yamada <akira@ruby-lang.org>
+# License::
+#   You can redistribute it and/or modify it under the same term as Ruby.
+#
+# See Bundler::URI for general documentation
+#
+
+require_relative "rfc2396_parser"
+require_relative "rfc3986_parser"
+
+module Bundler::URI
+  # The default parser instance for RFC 2396.
+  RFC2396_PARSER = RFC2396_Parser.new
+  Ractor.make_shareable(RFC2396_PARSER) if defined?(Ractor)
+
+  # The default parser instance for RFC 3986.
+  RFC3986_PARSER = RFC3986_Parser.new
+  Ractor.make_shareable(RFC3986_PARSER) if defined?(Ractor)
+
+  # The default parser instance.
+  DEFAULT_PARSER = RFC3986_PARSER
+  Ractor.make_shareable(DEFAULT_PARSER) if defined?(Ractor)
+
+  # Set the default parser instance.
+  def self.parser=(parser = RFC3986_PARSER)
+    remove_const(:Parser) if defined?(::Bundler::URI::Parser)
+    const_set("Parser", parser.class)
+
+    remove_const(:PARSER) if defined?(::Bundler::URI::PARSER)
+    const_set("PARSER", parser)
+
+    remove_const(:REGEXP) if defined?(::Bundler::URI::REGEXP)
+    remove_const(:PATTERN) if defined?(::Bundler::URI::PATTERN)
+    if Parser == RFC2396_Parser
+      const_set("REGEXP", Bundler::URI::RFC2396_REGEXP)
+      const_set("PATTERN", Bundler::URI::RFC2396_REGEXP::PATTERN)
+    end
+
+    Parser.new.regexp.each_pair do |sym, str|
+      remove_const(sym) if const_defined?(sym, false)
+      const_set(sym, str)
+    end
+  end
+  self.parser = RFC3986_PARSER
+
+  def self.const_missing(const) # :nodoc:
+    if const == :REGEXP
+      warn "Bundler::URI::REGEXP is obsolete. Use Bundler::URI::RFC2396_REGEXP explicitly.", uplevel: 1 if $VERBOSE
+      Bundler::URI::RFC2396_REGEXP
+    elsif value = RFC2396_PARSER.regexp[const]
+      warn "Bundler::URI::#{const} is obsolete. Use Bundler::URI::RFC2396_PARSER.regexp[#{const.inspect}] explicitly.", uplevel: 1 if $VERBOSE
+      value
+    elsif value = RFC2396_Parser.const_get(const)
+      warn "Bundler::URI::#{const} is obsolete. Use Bundler::URI::RFC2396_Parser::#{const} explicitly.", uplevel: 1 if $VERBOSE
+      value
+    else
+      super
+    end
+  end
+
+  module Util # :nodoc:
+    def make_components_hash(klass, array_hash)
+      tmp = {}
+      if array_hash.kind_of?(Array) &&
+          array_hash.size == klass.component.size - 1
+        klass.component[1..-1].each_index do |i|
+          begin
+            tmp[klass.component[i + 1]] = array_hash[i].clone
+          rescue TypeError
+            tmp[klass.component[i + 1]] = array_hash[i]
+          end
+        end
+
+      elsif array_hash.kind_of?(Hash)
+        array_hash.each do |key, value|
+          begin
+            tmp[key] = value.clone
+          rescue TypeError
+            tmp[key] = value
+          end
+        end
+      else
+        raise ArgumentError,
+          "expected Array of or Hash of components of #{klass} (#{klass.component[1..-1].join(', ')})"
+      end
+      tmp[:scheme] = klass.to_s.sub(/\A.*::/, '').downcase
+
+      return tmp
+    end
+    module_function :make_components_hash
+  end
+
+  module Schemes # :nodoc:
+    class << self
+      ReservedChars = ".+-"
+      EscapedChars = "\u01C0\u01C1\u01C2"
+      # Use Lo category chars as escaped chars for TruffleRuby, which
+      # does not allow Symbol categories as identifiers.
+
+      def escape(name)
+        unless name and name.ascii_only?
+          return nil
+        end
+        name.upcase.tr(ReservedChars, EscapedChars)
+      end
+
+      def unescape(name)
+        name.tr(EscapedChars, ReservedChars).encode(Encoding::US_ASCII).upcase
+      end
+
+      def find(name)
+        const_get(name, false) if name and const_defined?(name, false)
+      end
+
+      def register(name, klass)
+        unless scheme = escape(name)
+          raise ArgumentError, "invalid character as scheme - #{name}"
+        end
+        const_set(scheme, klass)
+      end
+
+      def list
+        constants.map { |name|
+          [unescape(name.to_s), const_get(name)]
+        }.to_h
+      end
+    end
+  end
+  private_constant :Schemes
+
+  # Registers the given +klass+ as the class to be instantiated
+  # when parsing a \Bundler::URI with the given +scheme+:
+  #
+  #   Bundler::URI.register_scheme('MS_SEARCH', Bundler::URI::Generic) # => Bundler::URI::Generic
+  #   Bundler::URI.scheme_list['MS_SEARCH']                   # => Bundler::URI::Generic
+  #
+  # Note that after calling String#upcase on +scheme+, it must be a valid
+  # constant name.
+  def self.register_scheme(scheme, klass)
+    Schemes.register(scheme, klass)
+  end
+
+  # Returns a hash of the defined schemes:
+  #
+  #   Bundler::URI.scheme_list
+  #   # =>
+  #   {"MAILTO"=>Bundler::URI::MailTo,
+  #    "LDAPS"=>Bundler::URI::LDAPS,
+  #    "WS"=>Bundler::URI::WS,
+  #    "HTTP"=>Bundler::URI::HTTP,
+  #    "HTTPS"=>Bundler::URI::HTTPS,
+  #    "LDAP"=>Bundler::URI::LDAP,
+  #    "FILE"=>Bundler::URI::File,
+  #    "FTP"=>Bundler::URI::FTP}
+  #
+  # Related: Bundler::URI.register_scheme.
+  def self.scheme_list
+    Schemes.list
+  end
+
+  # :stopdoc:
+  INITIAL_SCHEMES = scheme_list
+  private_constant :INITIAL_SCHEMES
+  Ractor.make_shareable(INITIAL_SCHEMES) if defined?(Ractor)
+  # :startdoc:
+
+  # Returns a new object constructed from the given +scheme+, +arguments+,
+  # and +default+:
+  #
+  # - The new object is an instance of <tt>Bundler::URI.scheme_list[scheme.upcase]</tt>.
+  # - The object is initialized by calling the class initializer
+  #   using +scheme+ and +arguments+.
+  #   See Bundler::URI::Generic.new.
+  #
+  # Examples:
+  #
+  #   values = ['john.doe', 'www.example.com', '123', nil, '/forum/questions/', nil, 'tag=networking&order=newest', 'top']
+  #   Bundler::URI.for('https', *values)
+  #   # => #<Bundler::URI::HTTPS https://john.doe@www.example.com:123/forum/questions/?tag=networking&order=newest#top>
+  #   Bundler::URI.for('foo', *values, default: Bundler::URI::HTTP)
+  #   # => #<Bundler::URI::HTTP foo://john.doe@www.example.com:123/forum/questions/?tag=networking&order=newest#top>
+  #
+  def self.for(scheme, *arguments, default: Generic)
+    const_name = Schemes.escape(scheme)
+
+    uri_class = INITIAL_SCHEMES[const_name]
+    uri_class ||= Schemes.find(const_name)
+    uri_class ||= default
+
+    return uri_class.new(scheme, *arguments)
+  end
+
+  #
+  # Base class for all Bundler::URI exceptions.
+  #
+  class Error < StandardError; end
+  #
+  # Not a Bundler::URI.
+  #
+  class InvalidURIError < Error; end
+  #
+  # Not a Bundler::URI component.
+  #
+  class InvalidComponentError < Error; end
+  #
+  # Bundler::URI is valid, bad usage is not.
+  #
+  class BadURIError < Error; end
+
+  # Returns a 9-element array representing the parts of the \Bundler::URI
+  # formed from the string +uri+;
+  # each array element is a string or +nil+:
+  #
+  #   names = %w[scheme userinfo host port registry path opaque query fragment]
+  #   values = Bundler::URI.split('https://john.doe@www.example.com:123/forum/questions/?tag=networking&order=newest#top')
+  #   names.zip(values)
+  #   # =>
+  #   [["scheme", "https"],
+  #    ["userinfo", "john.doe"],
+  #    ["host", "www.example.com"],
+  #    ["port", "123"],
+  #    ["registry", nil],
+  #    ["path", "/forum/questions/"],
+  #    ["opaque", nil],
+  #    ["query", "tag=networking&order=newest"],
+  #    ["fragment", "top"]]
+  #
+  def self.split(uri)
+    PARSER.split(uri)
+  end
+
+  # Returns a new \Bundler::URI object constructed from the given string +uri+:
+  #
+  #   Bundler::URI.parse('https://john.doe@www.example.com:123/forum/questions/?tag=networking&order=newest#top')
+  #   # => #<Bundler::URI::HTTPS https://john.doe@www.example.com:123/forum/questions/?tag=networking&order=newest#top>
+  #   Bundler::URI.parse('http://john.doe@www.example.com:123/forum/questions/?tag=networking&order=newest#top')
+  #   # => #<Bundler::URI::HTTP http://john.doe@www.example.com:123/forum/questions/?tag=networking&order=newest#top>
+  #
+  # It's recommended to first Bundler::URI::RFC2396_PARSER.escape string +uri+
+  # if it may contain invalid Bundler::URI characters.
+  #
+  def self.parse(uri)
+    PARSER.parse(uri)
+  end
+
+  # Merges the given Bundler::URI strings +str+
+  # per {RFC 2396}[https://www.rfc-editor.org/rfc/rfc2396.html].
+  #
+  # Each string in +str+ is converted to an
+  # {RFC3986 Bundler::URI}[https://www.rfc-editor.org/rfc/rfc3986.html] before being merged.
+  #
+  # Examples:
+  #
+  #   Bundler::URI.join("http://example.com/","main.rbx")
+  #   # => #<Bundler::URI::HTTP http://example.com/main.rbx>
+  #
+  #   Bundler::URI.join('http://example.com', 'foo')
+  #   # => #<Bundler::URI::HTTP http://example.com/foo>
+  #
+  #   Bundler::URI.join('http://example.com', '/foo', '/bar')
+  #   # => #<Bundler::URI::HTTP http://example.com/bar>
+  #
+  #   Bundler::URI.join('http://example.com', '/foo', 'bar')
+  #   # => #<Bundler::URI::HTTP http://example.com/bar>
+  #
+  #   Bundler::URI.join('http://example.com', '/foo/', 'bar')
+  #   # => #<Bundler::URI::HTTP http://example.com/foo/bar>
+  #
+  def self.join(*str)
+    DEFAULT_PARSER.join(*str)
+  end
+
+  #
+  # == Synopsis
+  #
+  #   Bundler::URI::extract(str[, schemes][,&blk])
+  #
+  # == Args
+  #
+  # +str+::
+  #   String to extract URIs from.
+  # +schemes+::
+  #   Limit Bundler::URI matching to specific schemes.
+  #
+  # == Description
+  #
+  # Extracts URIs from a string. If block given, iterates through all matched URIs.
+  # Returns nil if block given or array with matches.
+  #
+  # == Usage
+  #
+  #   require "bundler/vendor/uri/lib/uri"
+  #
+  #   Bundler::URI.extract("text here http://foo.example.org/bla and here mailto:test@example.com and here also.")
+  #   # => ["http://foo.example.com/bla", "mailto:test@example.com"]
+  #
+  def self.extract(str, schemes = nil, &block) # :nodoc:
+    warn "Bundler::URI.extract is obsolete", uplevel: 1 if $VERBOSE
+    PARSER.extract(str, schemes, &block)
+  end
+
+  #
+  # == Synopsis
+  #
+  #   Bundler::URI::regexp([match_schemes])
+  #
+  # == Args
+  #
+  # +match_schemes+::
+  #   Array of schemes. If given, resulting regexp matches to URIs
+  #   whose scheme is one of the match_schemes.
+  #
+  # == Description
+  #
+  # Returns a Regexp object which matches to Bundler::URI-like strings.
+  # The Regexp object returned by this method includes arbitrary
+  # number of capture group (parentheses).  Never rely on its number.
+  #
+  # == Usage
+  #
+  #   require 'bundler/vendor/uri/lib/uri'
+  #
+  #   # extract first Bundler::URI from html_string
+  #   html_string.slice(Bundler::URI.regexp)
+  #
+  #   # remove ftp URIs
+  #   html_string.sub(Bundler::URI.regexp(['ftp']), '')
+  #
+  #   # You should not rely on the number of parentheses
+  #   html_string.scan(Bundler::URI.regexp) do |*matches|
+  #     p $&
+  #   end
+  #
+  def self.regexp(schemes = nil)# :nodoc:
+    warn "Bundler::URI.regexp is obsolete", uplevel: 1 if $VERBOSE
+    PARSER.make_regexp(schemes)
+  end
+
+  TBLENCWWWCOMP_ = {} # :nodoc:
+  256.times do |i|
+    TBLENCWWWCOMP_[-i.chr] = -('%%%02X' % i)
+  end
+  TBLENCURICOMP_ = TBLENCWWWCOMP_.dup.freeze # :nodoc:
+  TBLENCWWWCOMP_[' '] = '+'
+  TBLENCWWWCOMP_.freeze
+  TBLDECWWWCOMP_ = {} # :nodoc:
+  256.times do |i|
+    h, l = i>>4, i&15
+    TBLDECWWWCOMP_[-('%%%X%X' % [h, l])] = -i.chr
+    TBLDECWWWCOMP_[-('%%%x%X' % [h, l])] = -i.chr
+    TBLDECWWWCOMP_[-('%%%X%x' % [h, l])] = -i.chr
+    TBLDECWWWCOMP_[-('%%%x%x' % [h, l])] = -i.chr
+  end
+  TBLDECWWWCOMP_['+'] = ' '
+  TBLDECWWWCOMP_.freeze
+
+  # Returns a URL-encoded string derived from the given string +str+.
+  #
+  # The returned string:
+  #
+  # - Preserves:
+  #
+  #   - Characters <tt>'*'</tt>, <tt>'.'</tt>, <tt>'-'</tt>, and <tt>'_'</tt>.
+  #   - Character in ranges <tt>'a'..'z'</tt>, <tt>'A'..'Z'</tt>,
+  #     and <tt>'0'..'9'</tt>.
+  #
+  #   Example:
+  #
+  #     Bundler::URI.encode_www_form_component('*.-_azAZ09')
+  #     # => "*.-_azAZ09"
+  #
+  # - Converts:
+  #
+  #   - Character <tt>' '</tt> to character <tt>'+'</tt>.
+  #   - Any other character to "percent notation";
+  #     the percent notation for character <i>c</i> is <tt>'%%%X' % c.ord</tt>.
+  #
+  #   Example:
+  #
+  #     Bundler::URI.encode_www_form_component('Here are some punctuation characters: ,;?:')
+  #     # => "Here+are+some+punctuation+characters%3A+%2C%3B%3F%3A"
+  #
+  # Encoding:
+  #
+  # - If +str+ has encoding Encoding::ASCII_8BIT, argument +enc+ is ignored.
+  # - Otherwise +str+ is converted first to Encoding::UTF_8
+  #   (with suitable character replacements),
+  #   and then to encoding +enc+.
+  #
+  # In either case, the returned string has forced encoding Encoding::US_ASCII.
+  #
+  # Related: Bundler::URI.encode_uri_component (encodes <tt>' '</tt> as <tt>'%20'</tt>).
+  def self.encode_www_form_component(str, enc=nil)
+    _encode_uri_component(/[^*\-.0-9A-Z_a-z]/, TBLENCWWWCOMP_, str, enc)
+  end
+
+  # Returns a string decoded from the given \URL-encoded string +str+.
+  #
+  # The given string is first encoded as Encoding::ASCII-8BIT (using String#b),
+  # then decoded (as below), and finally force-encoded to the given encoding +enc+.
+  #
+  # The returned string:
+  #
+  # - Preserves:
+  #
+  #   - Characters <tt>'*'</tt>, <tt>'.'</tt>, <tt>'-'</tt>, and <tt>'_'</tt>.
+  #   - Character in ranges <tt>'a'..'z'</tt>, <tt>'A'..'Z'</tt>,
+  #     and <tt>'0'..'9'</tt>.
+  #
+  #   Example:
+  #
+  #     Bundler::URI.decode_www_form_component('*.-_azAZ09')
+  #     # => "*.-_azAZ09"
+  #
+  # - Converts:
+  #
+  #   - Character <tt>'+'</tt> to character <tt>' '</tt>.
+  #   - Each "percent notation" to an ASCII character.
+  #
+  #   Example:
+  #
+  #     Bundler::URI.decode_www_form_component('Here+are+some+punctuation+characters%3A+%2C%3B%3F%3A')
+  #     # => "Here are some punctuation characters: ,;?:"
+  #
+  # Related: Bundler::URI.decode_uri_component (preserves <tt>'+'</tt>).
+  def self.decode_www_form_component(str, enc=Encoding::UTF_8)
+    _decode_uri_component(/\+|%\h\h/, str, enc)
+  end
+
+  # Like Bundler::URI.encode_www_form_component, except that <tt>' '</tt> (space)
+  # is encoded as <tt>'%20'</tt> (instead of <tt>'+'</tt>).
+  def self.encode_uri_component(str, enc=nil)
+    _encode_uri_component(/[^*\-.0-9A-Z_a-z]/, TBLENCURICOMP_, str, enc)
+  end
+
+  # Like Bundler::URI.decode_www_form_component, except that <tt>'+'</tt> is preserved.
+  def self.decode_uri_component(str, enc=Encoding::UTF_8)
+    _decode_uri_component(/%\h\h/, str, enc)
+  end
+
+  # Returns a string derived from the given string +str+ with
+  # Bundler::URI-encoded characters matching +regexp+ according to +table+.
+  def self._encode_uri_component(regexp, table, str, enc)
+    str = str.to_s.dup
+    if str.encoding != Encoding::ASCII_8BIT
+      if enc && enc != Encoding::ASCII_8BIT
+        str.encode!(Encoding::UTF_8, invalid: :replace, undef: :replace)
+        str.encode!(enc, fallback: ->(x){"&##{x.ord};"})
+      end
+      str.force_encoding(Encoding::ASCII_8BIT)
+    end
+    str.gsub!(regexp, table)
+    str.force_encoding(Encoding::US_ASCII)
+  end
+  private_class_method :_encode_uri_component
+
+  # Returns a string decoding characters matching +regexp+ from the
+  # given \URL-encoded string +str+.
+  def self._decode_uri_component(regexp, str, enc)
+    raise ArgumentError, "invalid %-encoding (#{str})" if /%(?!\h\h)/.match?(str)
+    str.b.gsub(regexp, TBLDECWWWCOMP_).force_encoding(enc)
+  end
+  private_class_method :_decode_uri_component
+
+  # Returns a URL-encoded string derived from the given
+  # {Enumerable}[rdoc-ref:Enumerable@Enumerable+in+Ruby+Classes]
+  # +enum+.
+  #
+  # The result is suitable for use as form data
+  # for an \HTTP request whose <tt>Content-Type</tt> is
+  # <tt>'application/x-www-form-urlencoded'</tt>.
+  #
+  # The returned string consists of the elements of +enum+,
+  # each converted to one or more URL-encoded strings,
+  # and all joined with character <tt>'&'</tt>.
+  #
+  # Simple examples:
+  #
+  #   Bundler::URI.encode_www_form([['foo', 0], ['bar', 1], ['baz', 2]])
+  #   # => "foo=0&bar=1&baz=2"
+  #   Bundler::URI.encode_www_form({foo: 0, bar: 1, baz: 2})
+  #   # => "foo=0&bar=1&baz=2"
+  #
+  # The returned string is formed using method Bundler::URI.encode_www_form_component,
+  # which converts certain characters:
+  #
+  #   Bundler::URI.encode_www_form('f#o': '/', 'b-r': '$', 'b z': '@')
+  #   # => "f%23o=%2F&b-r=%24&b+z=%40"
+  #
+  # When +enum+ is Array-like, each element +ele+ is converted to a field:
+  #
+  # - If +ele+ is an array of two or more elements,
+  #   the field is formed from its first two elements
+  #   (and any additional elements are ignored):
+  #
+  #     name = Bundler::URI.encode_www_form_component(ele[0], enc)
+  #     value = Bundler::URI.encode_www_form_component(ele[1], enc)
+  #     "#{name}=#{value}"
+  #
+  #   Examples:
+  #
+  #     Bundler::URI.encode_www_form([%w[foo bar], %w[baz bat bah]])
+  #     # => "foo=bar&baz=bat"
+  #     Bundler::URI.encode_www_form([['foo', 0], ['bar', :baz, 'bat']])
+  #     # => "foo=0&bar=baz"
+  #
+  # - If +ele+ is an array of one element,
+  #   the field is formed from <tt>ele[0]</tt>:
+  #
+  #     Bundler::URI.encode_www_form_component(ele[0])
+  #
+  #   Example:
+  #
+  #     Bundler::URI.encode_www_form([['foo'], [:bar], [0]])
+  #     # => "foo&bar&0"
+  #
+  # - Otherwise the field is formed from +ele+:
+  #
+  #     Bundler::URI.encode_www_form_component(ele)
+  #
+  #   Example:
+  #
+  #     Bundler::URI.encode_www_form(['foo', :bar, 0])
+  #     # => "foo&bar&0"
+  #
+  # The elements of an Array-like +enum+ may be mixture:
+  #
+  #   Bundler::URI.encode_www_form([['foo', 0], ['bar', 1, 2], ['baz'], :bat])
+  #   # => "foo=0&bar=1&baz&bat"
+  #
+  # When +enum+ is Hash-like,
+  # each +key+/+value+ pair is converted to one or more fields:
+  #
+  # - If +value+ is
+  #   {Array-convertible}[rdoc-ref:implicit_conversion.rdoc@Array-Convertible+Objects],
+  #   each element +ele+ in +value+ is paired with +key+ to form a field:
+  #
+  #     name = Bundler::URI.encode_www_form_component(key, enc)
+  #     value = Bundler::URI.encode_www_form_component(ele, enc)
+  #     "#{name}=#{value}"
+  #
+  #   Example:
+  #
+  #     Bundler::URI.encode_www_form({foo: [:bar, 1], baz: [:bat, :bam, 2]})
+  #     # => "foo=bar&foo=1&baz=bat&baz=bam&baz=2"
+  #
+  # - Otherwise, +key+ and +value+ are paired to form a field:
+  #
+  #     name = Bundler::URI.encode_www_form_component(key, enc)
+  #     value = Bundler::URI.encode_www_form_component(value, enc)
+  #     "#{name}=#{value}"
+  #
+  #   Example:
+  #
+  #     Bundler::URI.encode_www_form({foo: 0, bar: 1, baz: 2})
+  #     # => "foo=0&bar=1&baz=2"
+  #
+  # The elements of a Hash-like +enum+ may be mixture:
+  #
+  #   Bundler::URI.encode_www_form({foo: [0, 1], bar: 2})
+  #   # => "foo=0&foo=1&bar=2"
+  #
+  def self.encode_www_form(enum, enc=nil)
+    enum.map do |k,v|
+      if v.nil?
+        encode_www_form_component(k, enc)
+      elsif v.respond_to?(:to_ary)
+        v.to_ary.map do |w|
+          str = encode_www_form_component(k, enc)
+          unless w.nil?
+            str << '='
+            str << encode_www_form_component(w, enc)
+          end
+        end.join('&')
+      else
+        str = encode_www_form_component(k, enc)
+        str << '='
+        str << encode_www_form_component(v, enc)
+      end
+    end.join('&')
+  end
+
+  # Returns name/value pairs derived from the given string +str+,
+  # which must be an ASCII string.
+  #
+  # The method may be used to decode the body of Net::HTTPResponse object +res+
+  # for which <tt>res['Content-Type']</tt> is <tt>'application/x-www-form-urlencoded'</tt>.
+  #
+  # The returned data is an array of 2-element subarrays;
+  # each subarray is a name/value pair (both are strings).
+  # Each returned string has encoding +enc+,
+  # and has had invalid characters removed via
+  # {String#scrub}[rdoc-ref:String#scrub].
+  #
+  # A simple example:
+  #
+  #   Bundler::URI.decode_www_form('foo=0&bar=1&baz')
+  #   # => [["foo", "0"], ["bar", "1"], ["baz", ""]]
+  #
+  # The returned strings have certain conversions,
+  # similar to those performed in Bundler::URI.decode_www_form_component:
+  #
+  #   Bundler::URI.decode_www_form('f%23o=%2F&b-r=%24&b+z=%40')
+  #   # => [["f#o", "/"], ["b-r", "$"], ["b z", "@"]]
+  #
+  # The given string may contain consecutive separators:
+  #
+  #   Bundler::URI.decode_www_form('foo=0&&bar=1&&baz=2')
+  #   # => [["foo", "0"], ["", ""], ["bar", "1"], ["", ""], ["baz", "2"]]
+  #
+  # A different separator may be specified:
+  #
+  #   Bundler::URI.decode_www_form('foo=0--bar=1--baz', separator: '--')
+  #   # => [["foo", "0"], ["bar", "1"], ["baz", ""]]
+  #
+  def self.decode_www_form(str, enc=Encoding::UTF_8, separator: '&', use__charset_: false, isindex: false)
+    raise ArgumentError, "the input of #{self.name}.#{__method__} must be ASCII only string" unless str.ascii_only?
+    ary = []
+    return ary if str.empty?
+    enc = Encoding.find(enc)
+    str.b.each_line(separator) do |string|
+      string.chomp!(separator)
+      key, sep, val = string.partition('=')
+      if isindex
+        if sep.empty?
+          val = key
+          key = +''
+        end
+        isindex = false
+      end
+
+      if use__charset_ and key == '_charset_' and e = get_encoding(val)
+        enc = e
+        use__charset_ = false
+      end
+
+      key.gsub!(/\+|%\h\h/, TBLDECWWWCOMP_)
+      if val
+        val.gsub!(/\+|%\h\h/, TBLDECWWWCOMP_)
+      else
+        val = +''
+      end
+
+      ary << [key, val]
+    end
+    ary.each do |k, v|
+      k.force_encoding(enc)
+      k.scrub!
+      v.force_encoding(enc)
+      v.scrub!
+    end
+    ary
+  end
+
+  private
+=begin command for WEB_ENCODINGS_
+  curl https://encoding.spec.whatwg.org/encodings.json|
+  ruby -rjson -e 'H={}
+  h={
+    "shift_jis"=>"Windows-31J",
+    "euc-jp"=>"cp51932",
+    "iso-2022-jp"=>"cp50221",
+    "x-mac-cyrillic"=>"macCyrillic",
+  }
+  JSON($<.read).map{|x|x["encodings"]}.flatten.each{|x|
+    Encoding.find(n=h.fetch(n=x["name"].downcase,n))rescue next
+    x["labels"].each{|y|H[y]=n}
+  }
+  puts "{"
+  H.each{|k,v|puts %[  #{k.dump}=>#{v.dump},]}
+  puts "}"
+'
+=end
+  WEB_ENCODINGS_ = {
+    "unicode-1-1-utf-8"=>"utf-8",
+    "utf-8"=>"utf-8",
+    "utf8"=>"utf-8",
+    "866"=>"ibm866",
+    "cp866"=>"ibm866",
+    "csibm866"=>"ibm866",
+    "ibm866"=>"ibm866",
+    "csisolatin2"=>"iso-8859-2",
+    "iso-8859-2"=>"iso-8859-2",
+    "iso-ir-101"=>"iso-8859-2",
+    "iso8859-2"=>"iso-8859-2",
+    "iso88592"=>"iso-8859-2",
+    "iso_8859-2"=>"iso-8859-2",
+    "iso_8859-2:1987"=>"iso-8859-2",
+    "l2"=>"iso-8859-2",
+    "latin2"=>"iso-8859-2",
+    "csisolatin3"=>"iso-8859-3",
+    "iso-8859-3"=>"iso-8859-3",
+    "iso-ir-109"=>"iso-8859-3",
+    "iso8859-3"=>"iso-8859-3",
+    "iso88593"=>"iso-8859-3",
+    "iso_8859-3"=>"iso-8859-3",
+    "iso_8859-3:1988"=>"iso-8859-3",
+    "l3"=>"iso-8859-3",
+    "latin3"=>"iso-8859-3",
+    "csisolatin4"=>"iso-8859-4",
+    "iso-8859-4"=>"iso-8859-4",
+    "iso-ir-110"=>"iso-8859-4",
+    "iso8859-4"=>"iso-8859-4",
+    "iso88594"=>"iso-8859-4",
+    "iso_8859-4"=>"iso-8859-4",
+    "iso_8859-4:1988"=>"iso-8859-4",
+    "l4"=>"iso-8859-4",
+    "latin4"=>"iso-8859-4",
+    "csisolatincyrillic"=>"iso-8859-5",
+    "cyrillic"=>"iso-8859-5",
+    "iso-8859-5"=>"iso-8859-5",
+    "iso-ir-144"=>"iso-8859-5",
+    "iso8859-5"=>"iso-8859-5",
+    "iso88595"=>"iso-8859-5",
+    "iso_8859-5"=>"iso-8859-5",
+    "iso_8859-5:1988"=>"iso-8859-5",
+    "arabic"=>"iso-8859-6",
+    "asmo-708"=>"iso-8859-6",
+    "csiso88596e"=>"iso-8859-6",
+    "csiso88596i"=>"iso-8859-6",
+    "csisolatinarabic"=>"iso-8859-6",
+    "ecma-114"=>"iso-8859-6",
+    "iso-8859-6"=>"iso-8859-6",
+    "iso-8859-6-e"=>"iso-8859-6",
+    "iso-8859-6-i"=>"iso-8859-6",
+    "iso-ir-127"=>"iso-8859-6",
+    "iso8859-6"=>"iso-8859-6",
+    "iso88596"=>"iso-8859-6",
+    "iso_8859-6"=>"iso-8859-6",
+    "iso_8859-6:1987"=>"iso-8859-6",
+    "csisolatingreek"=>"iso-8859-7",
+    "ecma-118"=>"iso-8859-7",
+    "elot_928"=>"iso-8859-7",
+    "greek"=>"iso-8859-7",
+    "greek8"=>"iso-8859-7",
+    "iso-8859-7"=>"iso-8859-7",
+    "iso-ir-126"=>"iso-8859-7",
+    "iso8859-7"=>"iso-8859-7",
+    "iso88597"=>"iso-8859-7",
+    "iso_8859-7"=>"iso-8859-7",
+    "iso_8859-7:1987"=>"iso-8859-7",
+    "sun_eu_greek"=>"iso-8859-7",
+    "csiso88598e"=>"iso-8859-8",
+    "csisolatinhebrew"=>"iso-8859-8",
+    "hebrew"=>"iso-8859-8",
+    "iso-8859-8"=>"iso-8859-8",
+    "iso-8859-8-e"=>"iso-8859-8",
+    "iso-ir-138"=>"iso-8859-8",
+    "iso8859-8"=>"iso-8859-8",
+    "iso88598"=>"iso-8859-8",
+    "iso_8859-8"=>"iso-8859-8",
+    "iso_8859-8:1988"=>"iso-8859-8",
+    "visual"=>"iso-8859-8",
+    "csisolatin6"=>"iso-8859-10",
+    "iso-8859-10"=>"iso-8859-10",
+    "iso-ir-157"=>"iso-8859-10",
+    "iso8859-10"=>"iso-8859-10",
+    "iso885910"=>"iso-8859-10",
+    "l6"=>"iso-8859-10",
+    "latin6"=>"iso-8859-10",
+    "iso-8859-13"=>"iso-8859-13",
+    "iso8859-13"=>"iso-8859-13",
+    "iso885913"=>"iso-8859-13",
+    "iso-8859-14"=>"iso-8859-14",
+    "iso8859-14"=>"iso-8859-14",
+    "iso885914"=>"iso-8859-14",
+    "csisolatin9"=>"iso-8859-15",
+    "iso-8859-15"=>"iso-8859-15",
+    "iso8859-15"=>"iso-8859-15",
+    "iso885915"=>"iso-8859-15",
+    "iso_8859-15"=>"iso-8859-15",
+    "l9"=>"iso-8859-15",
+    "iso-8859-16"=>"iso-8859-16",
+    "cskoi8r"=>"koi8-r",
+    "koi"=>"koi8-r",
+    "koi8"=>"koi8-r",
+    "koi8-r"=>"koi8-r",
+    "koi8_r"=>"koi8-r",
+    "koi8-ru"=>"koi8-u",
+    "koi8-u"=>"koi8-u",
+    "dos-874"=>"windows-874",
+    "iso-8859-11"=>"windows-874",
+    "iso8859-11"=>"windows-874",
+    "iso885911"=>"windows-874",
+    "tis-620"=>"windows-874",
+    "windows-874"=>"windows-874",
+    "cp1250"=>"windows-1250",
+    "windows-1250"=>"windows-1250",
+    "x-cp1250"=>"windows-1250",
+    "cp1251"=>"windows-1251",
+    "windows-1251"=>"windows-1251",
+    "x-cp1251"=>"windows-1251",
+    "ansi_x3.4-1968"=>"windows-1252",
+    "ascii"=>"windows-1252",
+    "cp1252"=>"windows-1252",
+    "cp819"=>"windows-1252",
+    "csisolatin1"=>"windows-1252",
+    "ibm819"=>"windows-1252",
+    "iso-8859-1"=>"windows-1252",
+    "iso-ir-100"=>"windows-1252",
+    "iso8859-1"=>"windows-1252",
+    "iso88591"=>"windows-1252",
+    "iso_8859-1"=>"windows-1252",
+    "iso_8859-1:1987"=>"windows-1252",
+    "l1"=>"windows-1252",
+    "latin1"=>"windows-1252",
+    "us-ascii"=>"windows-1252",
+    "windows-1252"=>"windows-1252",
+    "x-cp1252"=>"windows-1252",
+    "cp1253"=>"windows-1253",
+    "windows-1253"=>"windows-1253",
+    "x-cp1253"=>"windows-1253",
+    "cp1254"=>"windows-1254",
+    "csisolatin5"=>"windows-1254",
+    "iso-8859-9"=>"windows-1254",
+    "iso-ir-148"=>"windows-1254",
+    "iso8859-9"=>"windows-1254",
+    "iso88599"=>"windows-1254",
+    "iso_8859-9"=>"windows-1254",
+    "iso_8859-9:1989"=>"windows-1254",
+    "l5"=>"windows-1254",
+    "latin5"=>"windows-1254",
+    "windows-1254"=>"windows-1254",
+    "x-cp1254"=>"windows-1254",
+    "cp1255"=>"windows-1255",
+    "windows-1255"=>"windows-1255",
+    "x-cp1255"=>"windows-1255",
+    "cp1256"=>"windows-1256",
+    "windows-1256"=>"windows-1256",
+    "x-cp1256"=>"windows-1256",
+    "cp1257"=>"windows-1257",
+    "windows-1257"=>"windows-1257",
+    "x-cp1257"=>"windows-1257",
+    "cp1258"=>"windows-1258",
+    "windows-1258"=>"windows-1258",
+    "x-cp1258"=>"windows-1258",
+    "x-mac-cyrillic"=>"macCyrillic",
+    "x-mac-ukrainian"=>"macCyrillic",
+    "chinese"=>"gbk",
+    "csgb2312"=>"gbk",
+    "csiso58gb231280"=>"gbk",
+    "gb2312"=>"gbk",
+    "gb_2312"=>"gbk",
+    "gb_2312-80"=>"gbk",
+    "gbk"=>"gbk",
+    "iso-ir-58"=>"gbk",
+    "x-gbk"=>"gbk",
+    "gb18030"=>"gb18030",
+    "big5"=>"big5",
+    "big5-hkscs"=>"big5",
+    "cn-big5"=>"big5",
+    "csbig5"=>"big5",
+    "x-x-big5"=>"big5",
+    "cseucpkdfmtjapanese"=>"cp51932",
+    "euc-jp"=>"cp51932",
+    "x-euc-jp"=>"cp51932",
+    "csiso2022jp"=>"cp50221",
+    "iso-2022-jp"=>"cp50221",
+    "csshiftjis"=>"Windows-31J",
+    "ms932"=>"Windows-31J",
+    "ms_kanji"=>"Windows-31J",
+    "shift-jis"=>"Windows-31J",
+    "shift_jis"=>"Windows-31J",
+    "sjis"=>"Windows-31J",
+    "windows-31j"=>"Windows-31J",
+    "x-sjis"=>"Windows-31J",
+    "cseuckr"=>"euc-kr",
+    "csksc56011987"=>"euc-kr",
+    "euc-kr"=>"euc-kr",
+    "iso-ir-149"=>"euc-kr",
+    "korean"=>"euc-kr",
+    "ks_c_5601-1987"=>"euc-kr",
+    "ks_c_5601-1989"=>"euc-kr",
+    "ksc5601"=>"euc-kr",
+    "ksc_5601"=>"euc-kr",
+    "windows-949"=>"euc-kr",
+    "utf-16be"=>"utf-16be",
+    "utf-16"=>"utf-16le",
+    "utf-16le"=>"utf-16le",
+  } # :nodoc:
+  Ractor.make_shareable(WEB_ENCODINGS_) if defined?(Ractor)
+
+  # :nodoc:
+  # return encoding or nil
+  # http://encoding.spec.whatwg.org/#concept-encoding-get
+  def self.get_encoding(label)
+    Encoding.find(WEB_ENCODINGS_[label.to_str.strip.downcase]) rescue nil
+  end
+end # module Bundler::URI
+
+module Bundler
+
+  #
+  # Returns a \Bundler::URI object derived from the given +uri+,
+  # which may be a \Bundler::URI string or an existing \Bundler::URI object:
+  #
+  #   require 'bundler/vendor/uri/lib/uri'
+  #   # Returns a new Bundler::URI.
+  #   uri = Bundler::URI('http://github.com/ruby/ruby')
+  #   # => #<Bundler::URI::HTTP http://github.com/ruby/ruby>
+  #   # Returns the given Bundler::URI.
+  #   Bundler::URI(uri)
+  #   # => #<Bundler::URI::HTTP http://github.com/ruby/ruby>
+  #
+  # You must require 'bundler/vendor/uri/lib/uri' to use this method.
+  #
+  def URI(uri)
+    if uri.is_a?(Bundler::URI::Generic)
+      uri
+    elsif uri = String.try_convert(uri)
+      Bundler::URI.parse(uri)
+    else
+      raise ArgumentError,
+        "bad argument (expected Bundler::URI object or Bundler::URI string)"
+    end
+  end
+  module_function :URI
+end
diff --git a/lib/bundler/vendor/uri/lib/uri/file.rb b/lib/bundler/vendor/uri/lib/uri/file.rb
new file mode 100644
index 0000000000..21dd9ee535
--- /dev/null
+++ b/lib/bundler/vendor/uri/lib/uri/file.rb
@@ -0,0 +1,100 @@
+# frozen_string_literal: true
+
+require_relative 'generic'
+
+module Bundler::URI
+
+  #
+  # The "file" Bundler::URI is defined by RFC8089.
+  #
+  class File < Generic
+    # A Default port of nil for Bundler::URI::File.
+    DEFAULT_PORT = nil
+
+    #
+    # An Array of the available components for Bundler::URI::File.
+    #
+    COMPONENT = [
+      :scheme,
+      :host,
+      :path
+    ].freeze
+
+    #
+    # == Description
+    #
+    # Creates a new Bundler::URI::File object from components, with syntax checking.
+    #
+    # The components accepted are +host+ and +path+.
+    #
+    # The components should be provided either as an Array, or as a Hash
+    # with keys formed by preceding the component names with a colon.
+    #
+    # If an Array is used, the components must be passed in the
+    # order <code>[host, path]</code>.
+    #
+    # A path from e.g. the File class should be escaped before
+    # being passed.
+    #
+    # Examples:
+    #
+    #     require 'bundler/vendor/uri/lib/uri'
+    #
+    #     uri1 = Bundler::URI::File.build(['host.example.com', '/path/file.zip'])
+    #     uri1.to_s  # => "file://host.example.com/path/file.zip"
+    #
+    #     uri2 = Bundler::URI::File.build({:host => 'host.example.com',
+    #       :path => '/ruby/src'})
+    #     uri2.to_s  # => "file://host.example.com/ruby/src"
+    #
+    #     uri3 = Bundler::URI::File.build({:path => Bundler::URI::RFC2396_PARSER.escape('/path/my file.txt')})
+    #     uri3.to_s  # => "file:///path/my%20file.txt"
+    #
+    def self.build(args)
+      tmp = Util::make_components_hash(self, args)
+      super(tmp)
+    end
+
+    # Protected setter for the host component +v+.
+    #
+    # See also Bundler::URI::Generic.host=.
+    #
+    def set_host(v)
+      v = "" if v.nil? || v == "localhost"
+      @host = v
+    end
+
+    # do nothing
+    def set_port(v)
+    end
+
+    # raise InvalidURIError
+    def check_userinfo(user)
+      raise Bundler::URI::InvalidURIError, "cannot set userinfo for file Bundler::URI"
+    end
+
+    # raise InvalidURIError
+    def check_user(user)
+      raise Bundler::URI::InvalidURIError, "cannot set user for file Bundler::URI"
+    end
+
+    # raise InvalidURIError
+    def check_password(user)
+      raise Bundler::URI::InvalidURIError, "cannot set password for file Bundler::URI"
+    end
+
+    # do nothing
+    def set_userinfo(v)
+    end
+
+    # do nothing
+    def set_user(v)
+    end
+
+    # do nothing
+    def set_password(v)
+    end
+  end
+
+  register_scheme 'FILE', File
+end
diff --git a/lib/bundler/vendor/uri/lib/uri/ftp.rb b/lib/bundler/vendor/uri/lib/uri/ftp.rb
new file mode 100644
index 0000000000..f83985fd3d
--- /dev/null
+++ b/lib/bundler/vendor/uri/lib/uri/ftp.rb
@@ -0,0 +1,267 @@
+# frozen_string_literal: false
+# = uri/ftp.rb
+#
+# Author:: Akira Yamada <akira@ruby-lang.org>
+# License:: You can redistribute it and/or modify it under the same term as Ruby.
+#
+# See Bundler::URI for general documentation
+#
+
+require_relative 'generic'
+
+module Bundler::URI
+
+  #
+  # FTP Bundler::URI syntax is defined by RFC1738 section 3.2.
+  #
+  # This class will be redesigned because of difference of implementations;
+  # the structure of its path. draft-hoffman-ftp-uri-04 is a draft but it
+  # is a good summary about the de facto spec.
+  # https://datatracker.ietf.org/doc/html/draft-hoffman-ftp-uri-04
+  #
+  class FTP < Generic
+    # A Default port of 21 for Bundler::URI::FTP.
+    DEFAULT_PORT = 21
+
+    #
+    # An Array of the available components for Bundler::URI::FTP.
+    #
+    COMPONENT = [
+      :scheme,
+      :userinfo, :host, :port,
+      :path, :typecode
+    ].freeze
+
+    #
+    # Typecode is "a", "i", or "d".
+    #
+    # * "a" indicates a text file (the FTP command was ASCII)
+    # * "i" indicates a binary file (FTP command IMAGE)
+    # * "d" indicates the contents of a directory should be displayed
+    #
+    TYPECODE = ['a', 'i', 'd'].freeze
+
+    # Typecode prefix ";type=".
+    TYPECODE_PREFIX = ';type='.freeze
+
+    def self.new2(user, password, host, port, path,
+                  typecode = nil, arg_check = true) # :nodoc:
+      # Do not use this method!  Not tested.  [Bug #7301]
+      # This methods remains just for compatibility,
+      # Keep it undocumented until the active maintainer is assigned.
+      typecode = nil if typecode.size == 0
+      if typecode && !TYPECODE.include?(typecode)
+        raise ArgumentError,
+          "bad typecode is specified: #{typecode}"
+      end
+
+      # do escape
+
+      self.new('ftp',
+               [user, password],
+               host, port, nil,
+               typecode ? path + TYPECODE_PREFIX + typecode : path,
+               nil, nil, nil, arg_check)
+    end
+
+    #
+    # == Description
+    #
+    # Creates a new Bundler::URI::FTP object from components, with syntax checking.
+    #
+    # The components accepted are +userinfo+, +host+, +port+, +path+, and
+    # +typecode+.
+    #
+    # The components should be provided either as an Array, or as a Hash
+    # with keys formed by preceding the component names with a colon.
+    #
+    # If an Array is used, the components must be passed in the
+    # order <code>[userinfo, host, port, path, typecode]</code>.
+    #
+    # If the path supplied is absolute, it will be escaped in order to
+    # make it absolute in the Bundler::URI.
+    #
+    # Examples:
+    #
+    #     require 'bundler/vendor/uri/lib/uri'
+    #
+    #     uri1 = Bundler::URI::FTP.build(['user:password', 'ftp.example.com', nil,
+    #       '/path/file.zip', 'i'])
+    #     uri1.to_s  # => "ftp://user:password@ftp.example.com/%2Fpath/file.zip;type=i"
+    #
+    #     uri2 = Bundler::URI::FTP.build({:host => 'ftp.example.com',
+    #       :path => 'ruby/src'})
+    #     uri2.to_s  # => "ftp://ftp.example.com/ruby/src"
+    #
+    def self.build(args)
+
+      # Fix the incoming path to be generic URL syntax
+      # FTP path  ->  URL path
+      # foo/bar       /foo/bar
+      # /foo/bar      /%2Ffoo/bar
+      #
+      if args.kind_of?(Array)
+        args[3] = '/' + args[3].sub(/^\//, '%2F')
+      else
+        args[:path] = '/' + args[:path].sub(/^\//, '%2F')
+      end
+
+      tmp = Util::make_components_hash(self, args)
+
+      if tmp[:typecode]
+        if tmp[:typecode].size == 1
+          tmp[:typecode] = TYPECODE_PREFIX + tmp[:typecode]
+        end
+        tmp[:path] << tmp[:typecode]
+      end
+
+      return super(tmp)
+    end
+
+    #
+    # == Description
+    #
+    # Creates a new Bundler::URI::FTP object from generic URL components with no
+    # syntax checking.
+    #
+    # Unlike build(), this method does not escape the path component as
+    # required by RFC1738; instead it is treated as per RFC2396.
+    #
+    # Arguments are +scheme+, +userinfo+, +host+, +port+, +registry+, +path+,
+    # +opaque+, +query+, and +fragment+, in that order.
+    #
+    def initialize(scheme,
+                   userinfo, host, port, registry,
+                   path, opaque,
+                   query,
+                   fragment,
+                   parser = nil,
+                   arg_check = false)
+      raise InvalidURIError unless path
+      path = path.sub(/^\//,'')
+      path.sub!(/^%2F/,'/')
+      super(scheme, userinfo, host, port, registry, path, opaque,
+            query, fragment, parser, arg_check)
+      @typecode = nil
+      if tmp = @path.index(TYPECODE_PREFIX)
+        typecode = @path[tmp + TYPECODE_PREFIX.size..-1]
+        @path = @path[0..tmp - 1]
+
+        if arg_check
+          self.typecode = typecode
+        else
+          self.set_typecode(typecode)
+        end
+      end
+    end
+
+    # typecode accessor.
+    #
+    # See Bundler::URI::FTP::COMPONENT.
+    attr_reader :typecode
+
+    # Validates typecode +v+,
+    # returns +true+ or +false+.
+    #
+    def check_typecode(v)
+      if TYPECODE.include?(v)
+        return true
+      else
+        raise InvalidComponentError,
+          "bad typecode(expected #{TYPECODE.join(', ')}): #{v}"
+      end
+    end
+    private :check_typecode
+
+    # Private setter for the typecode +v+.
+    #
+    # See also Bundler::URI::FTP.typecode=.
+    #
+    def set_typecode(v)
+      @typecode = v
+    end
+    protected :set_typecode
+
+    #
+    # == Args
+    #
+    # +v+::
+    #    String
+    #
+    # == Description
+    #
+    # Public setter for the typecode +v+
+    # (with validation).
+    #
+    # See also Bundler::URI::FTP.check_typecode.
+    #
+    # == Usage
+    #
+    #   require 'bundler/vendor/uri/lib/uri'
+    #
+    #   uri = Bundler::URI.parse("ftp://john@ftp.example.com/my_file.img")
+    #   #=> #<Bundler::URI::FTP ftp://john@ftp.example.com/my_file.img>
+    #   uri.typecode = "i"
+    #   uri
+    #   #=> #<Bundler::URI::FTP ftp://john@ftp.example.com/my_file.img;type=i>
+    #
+    def typecode=(typecode)
+      check_typecode(typecode)
+      set_typecode(typecode)
+      typecode
+    end
+
+    def merge(oth) # :nodoc:
+      tmp = super(oth)
+      if self != tmp
+        tmp.set_typecode(oth.typecode)
+      end
+
+      return tmp
+    end
+
+    # Returns the path from an FTP Bundler::URI.
+    #
+    # RFC 1738 specifically states that the path for an FTP Bundler::URI does not
+    # include the / which separates the Bundler::URI path from the Bundler::URI host. Example:
+    #
+    # <code>ftp://ftp.example.com/pub/ruby</code>
+    #
+    # The above Bundler::URI indicates that the client should connect to
+    # ftp.example.com then cd to pub/ruby from the initial login directory.
+    #
+    # If you want to cd to an absolute directory, you must include an
+    # escaped / (%2F) in the path. Example:
+    #
+    # <code>ftp://ftp.example.com/%2Fpub/ruby</code>
+    #
+    # This method will then return "/pub/ruby".
+    #
+    def path
+      return @path.sub(/^\//,'').sub(/^%2F/,'/')
+    end
+
+    # Private setter for the path of the Bundler::URI::FTP.
+    def set_path(v)
+      super("/" + v.sub(/^\//, "%2F"))
+    end
+    protected :set_path
+
+    # Returns a String representation of the Bundler::URI::FTP.
+    def to_s
+      save_path = nil
+      if @typecode
+        save_path = @path
+        @path = @path + TYPECODE_PREFIX + @typecode
+      end
+      str = super
+      if @typecode
+        @path = save_path
+      end
+
+      return str
+    end
+  end
+
+  register_scheme 'FTP', FTP
+end
diff --git a/lib/bundler/vendor/uri/lib/uri/generic.rb b/lib/bundler/vendor/uri/lib/uri/generic.rb
new file mode 100644
index 0000000000..30dab60903
--- /dev/null
+++ b/lib/bundler/vendor/uri/lib/uri/generic.rb
@@ -0,0 +1,1592 @@
+# frozen_string_literal: true
+
+# = uri/generic.rb
+#
+# Author:: Akira Yamada <akira@ruby-lang.org>
+# License:: You can redistribute it and/or modify it under the same term as Ruby.
+#
+# See Bundler::URI for general documentation
+#
+
+require_relative 'common'
+autoload :IPSocket, 'socket'
+autoload :IPAddr, 'ipaddr'
+
+module Bundler::URI
+
+  #
+  # Base class for all Bundler::URI classes.
+  # Implements generic Bundler::URI syntax as per RFC 2396.
+  #
+  class Generic
+    include Bundler::URI
+
+    #
+    # A Default port of nil for Bundler::URI::Generic.
+    #
+    DEFAULT_PORT = nil
+
+    #
+    # Returns default port.
+    #
+    def self.default_port
+      self::DEFAULT_PORT
+    end
+
+    #
+    # Returns default port.
+    #
+    def default_port
+      self.class.default_port
+    end
+
+    #
+    # An Array of the available components for Bundler::URI::Generic.
+    #
+    COMPONENT = [
+      :scheme,
+      :userinfo, :host, :port, :registry,
+      :path, :opaque,
+      :query,
+      :fragment
+    ].freeze
+
+    #
+    # Components of the Bundler::URI in the order.
+    #
+    def self.component
+      self::COMPONENT
+    end
+
+    USE_REGISTRY = false # :nodoc:
+
+    def self.use_registry # :nodoc:
+      self::USE_REGISTRY
+    end
+
+    #
+    # == Synopsis
+    #
+    # See ::new.
+    #
+    # == Description
+    #
+    # At first, tries to create a new Bundler::URI::Generic instance using
+    # Bundler::URI::Generic::build. But, if exception Bundler::URI::InvalidComponentError is raised,
+    # then it does Bundler::URI::RFC2396_PARSER.escape all Bundler::URI components and tries again.
+    #
+    def self.build2(args)
+      begin
+        return self.build(args)
+      rescue InvalidComponentError
+        if args.kind_of?(Array)
+          return self.build(args.collect{|x|
+            if x.is_a?(String)
+              Bundler::URI::RFC2396_PARSER.escape(x)
+            else
+              x
+            end
+          })
+        elsif args.kind_of?(Hash)
+          tmp = {}
+          args.each do |key, value|
+            tmp[key] = if value
+                Bundler::URI::RFC2396_PARSER.escape(value)
+              else
+                value
+              end
+          end
+          return self.build(tmp)
+        end
+      end
+    end
+
+    #
+    # == Synopsis
+    #
+    # See ::new.
+    #
+    # == Description
+    #
+    # Creates a new Bundler::URI::Generic instance from components of Bundler::URI::Generic
+    # with check.  Components are: scheme, userinfo, host, port, registry, path,
+    # opaque, query, and fragment. You can provide arguments either by an Array or a Hash.
+    # See ::new for hash keys to use or for order of array items.
+    #
+    def self.build(args)
+      if args.kind_of?(Array) &&
+          args.size == ::Bundler::URI::Generic::COMPONENT.size
+        tmp = args.dup
+      elsif args.kind_of?(Hash)
+        tmp = ::Bundler::URI::Generic::COMPONENT.collect do |c|
+          if args.include?(c)
+            args[c]
+          else
+            nil
+          end
+        end
+      else
+        component = self.component rescue ::Bundler::URI::Generic::COMPONENT
+        raise ArgumentError,
+              "expected Array of or Hash of components of #{self} (#{component.join(', ')})"
+      end
+
+      tmp << nil
+      tmp << true
+      return self.new(*tmp)
+    end
+
+    #
+    # == Args
+    #
+    # +scheme+::
+    #   Protocol scheme, i.e. 'http','ftp','mailto' and so on.
+    # +userinfo+::
+    #   User name and password, i.e. 'sdmitry:bla'.
+    # +host+::
+    #   Server host name.
+    # +port+::
+    #   Server port.
+    # +registry+::
+    #   Registry of naming authorities.
+    # +path+::
+    #   Path on server.
+    # +opaque+::
+    #   Opaque part.
+    # +query+::
+    #   Query data.
+    # +fragment+::
+    #   Part of the Bundler::URI after '#' character.
+    # +parser+::
+    #   Parser for internal use [Bundler::URI::DEFAULT_PARSER by default].
+    # +arg_check+::
+    #   Check arguments [false by default].
+    #
+    # == Description
+    #
+    # Creates a new Bundler::URI::Generic instance from ``generic'' components without check.
+    #
+    def initialize(scheme,
+                   userinfo, host, port, registry,
+                   path, opaque,
+                   query,
+                   fragment,
+                   parser = DEFAULT_PARSER,
+                   arg_check = false)
+      @scheme = nil
+      @user = nil
+      @password = nil
+      @host = nil
+      @port = nil
+      @path = nil
+      @query = nil
+      @opaque = nil
+      @fragment = nil
+      @parser = parser == DEFAULT_PARSER ? nil : parser
+
+      if arg_check
+        self.scheme = scheme
+        self.hostname = host
+        self.port = port
+        self.userinfo = userinfo
+        self.path = path
+        self.query = query
+        self.opaque = opaque
+        self.fragment = fragment
+      else
+        self.set_scheme(scheme)
+        self.set_host(host)
+        self.set_port(port)
+        self.set_userinfo(userinfo)
+        self.set_path(path)
+        self.query = query
+        self.set_opaque(opaque)
+        self.fragment=(fragment)
+      end
+      if registry
+        raise InvalidURIError,
+          "the scheme #{@scheme} does not accept registry part: #{registry} (or bad hostname?)"
+      end
+
+      @scheme&.freeze
+      self.set_path('') if !@path && !@opaque # (see RFC2396 Section 5.2)
+      self.set_port(self.default_port) if self.default_port && !@port
+    end
+
+    #
+    # Returns the scheme component of the Bundler::URI.
+    #
+    #   Bundler::URI("http://foo/bar/baz").scheme #=> "http"
+    #
+    attr_reader :scheme
+
+    # Returns the host component of the Bundler::URI.
+    #
+    #   Bundler::URI("http://foo/bar/baz").host #=> "foo"
+    #
+    # It returns nil if no host component exists.
+    #
+    #   Bundler::URI("mailto:foo@example.org").host #=> nil
+    #
+    # The component does not contain the port number.
+    #
+    #   Bundler::URI("http://foo:8080/bar/baz").host #=> "foo"
+    #
+    # Since IPv6 addresses are wrapped with brackets in URIs,
+    # this method returns IPv6 addresses wrapped with brackets.
+    # This form is not appropriate to pass to socket methods such as TCPSocket.open.
+    # If unwrapped host names are required, use the #hostname method.
+    #
+    #   Bundler::URI("http://[::1]/bar/baz").host     #=> "[::1]"
+    #   Bundler::URI("http://[::1]/bar/baz").hostname #=> "::1"
+    #
+    attr_reader :host
+
+    # Returns the port component of the Bundler::URI.
+    #
+    #   Bundler::URI("http://foo/bar/baz").port      #=> 80
+    #   Bundler::URI("http://foo:8080/bar/baz").port #=> 8080
+    #
+    attr_reader :port
+
+    def registry # :nodoc:
+      nil
+    end
+
+    # Returns the path component of the Bundler::URI.
+    #
+    #   Bundler::URI("http://foo/bar/baz").path #=> "/bar/baz"
+    #
+    attr_reader :path
+
+    # Returns the query component of the Bundler::URI.
+    #
+    #   Bundler::URI("http://foo/bar/baz?search=FooBar").query #=> "search=FooBar"
+    #
+    attr_reader :query
+
+    # Returns the opaque part of the Bundler::URI.
+    #
+    #   Bundler::URI("mailto:foo@example.org").opaque #=> "foo@example.org"
+    #   Bundler::URI("http://foo/bar/baz").opaque     #=> nil
+    #
+    # The portion of the path that does not make use of the slash '/'.
+    # The path typically refers to an absolute path or an opaque part.
+    # (See RFC2396 Section 3 and 5.2.)
+    #
+    attr_reader :opaque
+
+    # Returns the fragment component of the Bundler::URI.
+    #
+    #   Bundler::URI("http://foo/bar/baz?search=FooBar#ponies").fragment #=> "ponies"
+    #
+    attr_reader :fragment
+
+    # Returns the parser to be used.
+    #
+    # Unless the +parser+ is defined, DEFAULT_PARSER is used.
+    #
+    def parser
+      if !defined?(@parser) || !@parser
+        DEFAULT_PARSER
+      else
+        @parser || DEFAULT_PARSER
+      end
+    end
+
+    # Replaces self by other Bundler::URI object.
+    #
+    def replace!(oth)
+      if self.class != oth.class
+        raise ArgumentError, "expected #{self.class} object"
+      end
+
+      component.each do |c|
+        self.__send__("#{c}=", oth.__send__(c))
+      end
+    end
+    private :replace!
+
+    #
+    # Components of the Bundler::URI in the order.
+    #
+    def component
+      self.class.component
+    end
+
+    #
+    # Checks the scheme +v+ component against the +parser+ Regexp for :SCHEME.
+    #
+    def check_scheme(v)
+      if v && parser.regexp[:SCHEME] !~ v
+        raise InvalidComponentError,
+          "bad component(expected scheme component): #{v}"
+      end
+
+      return true
+    end
+    private :check_scheme
+
+    # Protected setter for the scheme component +v+.
+    #
+    # See also Bundler::URI::Generic.scheme=.
+    #
+    def set_scheme(v)
+      @scheme = v&.downcase
+    end
+    protected :set_scheme
+
+    #
+    # == Args
+    #
+    # +v+::
+    #    String
+    #
+    # == Description
+    #
+    # Public setter for the scheme component +v+
+    # (with validation).
+    #
+    # See also Bundler::URI::Generic.check_scheme.
+    #
+    # == Usage
+    #
+    #   require 'bundler/vendor/uri/lib/uri'
+    #
+    #   uri = Bundler::URI.parse("http://my.example.com")
+    #   uri.scheme = "https"
+    #   uri.to_s  #=> "https://my.example.com"
+    #
+    def scheme=(v)
+      check_scheme(v)
+      set_scheme(v)
+      v
+    end
+
+    #
+    # Checks the +user+ and +password+.
+    #
+    # If +password+ is not provided, then +user+ is
+    # split, using Bundler::URI::Generic.split_userinfo, to
+    # pull +user+ and +password.
+    #
+    # See also Bundler::URI::Generic.check_user, Bundler::URI::Generic.check_password.
+    #
+    def check_userinfo(user, password = nil)
+      if !password
+        user, password = split_userinfo(user)
+      end
+      check_user(user)
+      check_password(password, user)
+
+      return true
+    end
+    private :check_userinfo
+
+    #
+    # Checks the user +v+ component for RFC2396 compliance
+    # and against the +parser+ Regexp for :USERINFO.
+    #
+    # Can not have a registry or opaque component defined,
+    # with a user component defined.
+    #
+    def check_user(v)
+      if @opaque
+        raise InvalidURIError,
+          "cannot set user with opaque"
+      end
+
+      return v unless v
+
+      if parser.regexp[:USERINFO] !~ v
+        raise InvalidComponentError,
+          "bad component(expected userinfo component or user component): #{v}"
+      end
+
+      return true
+    end
+    private :check_user
+
+    #
+    # Checks the password +v+ component for RFC2396 compliance
+    # and against the +parser+ Regexp for :USERINFO.
+    #
+    # Can not have a registry or opaque component defined,
+    # with a user component defined.
+    #
+    def check_password(v, user = @user)
+      if @opaque
+        raise InvalidURIError,
+          "cannot set password with opaque"
+      end
+      return v unless v
+
+      if !user
+        raise InvalidURIError,
+          "password component depends user component"
+      end
+
+      if parser.regexp[:USERINFO] !~ v
+        raise InvalidComponentError,
+          "bad password component"
+      end
+
+      return true
+    end
+    private :check_password
+
+    #
+    # Sets userinfo, argument is string like 'name:pass'.
+    #
+    def userinfo=(userinfo)
+      if userinfo.nil?
+        return nil
+      end
+      check_userinfo(*userinfo)
+      set_userinfo(*userinfo)
+      # returns userinfo
+    end
+
+    #
+    # == Args
+    #
+    # +v+::
+    #    String
+    #
+    # == Description
+    #
+    # Public setter for the +user+ component
+    # (with validation).
+    #
+    # See also Bundler::URI::Generic.check_user.
+    #
+    # == Usage
+    #
+    #   require 'bundler/vendor/uri/lib/uri'
+    #
+    #   uri = Bundler::URI.parse("http://john:S3nsit1ve@my.example.com")
+    #   uri.user = "sam"
+    #   uri.to_s  #=> "http://sam:V3ry_S3nsit1ve@my.example.com"
+    #
+    def user=(user)
+      check_user(user)
+      set_user(user)
+      # returns user
+    end
+
+    #
+    # == Args
+    #
+    # +v+::
+    #    String
+    #
+    # == Description
+    #
+    # Public setter for the +password+ component
+    # (with validation).
+    #
+    # See also Bundler::URI::Generic.check_password.
+    #
+    # == Usage
+    #
+    #   require 'bundler/vendor/uri/lib/uri'
+    #
+    #   uri = Bundler::URI.parse("http://john:S3nsit1ve@my.example.com")
+    #   uri.password = "V3ry_S3nsit1ve"
+    #   uri.to_s  #=> "http://john:V3ry_S3nsit1ve@my.example.com"
+    #
+    def password=(password)
+      check_password(password)
+      set_password(password)
+      # returns password
+    end
+
+    # Protected setter for the +user+ component, and +password+ if available
+    # (with validation).
+    #
+    # See also Bundler::URI::Generic.userinfo=.
+    #
+    def set_userinfo(user, password = nil)
+      unless password
+        user, password = split_userinfo(user)
+      end
+      @user     = user
+      @password = password
+
+      [@user, @password]
+    end
+    protected :set_userinfo
+
+    # Protected setter for the user component +v+.
+    #
+    # See also Bundler::URI::Generic.user=.
+    #
+    def set_user(v)
+      set_userinfo(v, nil)
+      v
+    end
+    protected :set_user
+
+    # Protected setter for the password component +v+.
+    #
+    # See also Bundler::URI::Generic.password=.
+    #
+    def set_password(v)
+      @password = v
+      # returns v
+    end
+    protected :set_password
+
+    # Returns the userinfo +ui+ as <code>[user, password]</code>
+    # if properly formatted as 'user:password'.
+    def split_userinfo(ui)
+      return nil, nil unless ui
+      user, password = ui.split(':', 2)
+
+      return user, password
+    end
+    private :split_userinfo
+
+    # Escapes 'user:password' +v+ based on RFC 1738 section 3.1.
+    def escape_userpass(v)
+      parser.escape(v, /[@:\/]/o) # RFC 1738 section 3.1 #/
+    end
+    private :escape_userpass
+
+    # Returns the userinfo, either as 'user' or 'user:password'.
+    def userinfo
+      if @user.nil?
+        nil
+      elsif @password.nil?
+        @user
+      else
+        @user + ':' + @password
+      end
+    end
+
+    # Returns the user component (without Bundler::URI decoding).
+    def user
+      @user
+    end
+
+    # Returns the password component (without Bundler::URI decoding).
+    def password
+      @password
+    end
+
+    # Returns the authority info (array of user, password, host and
+    # port), if any is set.  Or returns +nil+.
+    def authority
+      return @user, @password, @host, @port if @user || @password || @host || @port
+    end
+
+    # Returns the user component after Bundler::URI decoding.
+    def decoded_user
+      Bundler::URI.decode_uri_component(@user) if @user
+    end
+
+    # Returns the password component after Bundler::URI decoding.
+    def decoded_password
+      Bundler::URI.decode_uri_component(@password) if @password
+    end
+
+    #
+    # Checks the host +v+ component for RFC2396 compliance
+    # and against the +parser+ Regexp for :HOST.
+    #
+    # Can not have a registry or opaque component defined,
+    # with a host component defined.
+    #
+    def check_host(v)
+      return v unless v
+
+      if @opaque
+        raise InvalidURIError,
+          "cannot set host with registry or opaque"
+      elsif parser.regexp[:HOST] !~ v
+        raise InvalidComponentError,
+          "bad component(expected host component): #{v}"
+      end
+
+      return true
+    end
+    private :check_host
+
+    # Protected setter for the host component +v+.
+    #
+    # See also Bundler::URI::Generic.host=.
+    #
+    def set_host(v)
+      @host = v
+    end
+    protected :set_host
+
+    # Protected setter for the authority info (+user+, +password+, +host+
+    # and +port+).  If +port+ is +nil+, +default_port+ will be set.
+    #
+    protected def set_authority(user, password, host, port = nil)
+      @user, @password, @host, @port = user, password, host, port || self.default_port
+    end
+
+    #
+    # == Args
+    #
+    # +v+::
+    #    String
+    #
+    # == Description
+    #
+    # Public setter for the host component +v+
+    # (with validation).
+    #
+    # See also Bundler::URI::Generic.check_host.
+    #
+    # == Usage
+    #
+    #   require 'bundler/vendor/uri/lib/uri'
+    #
+    #   uri = Bundler::URI.parse("http://my.example.com")
+    #   uri.host = "foo.com"
+    #   uri.to_s  #=> "http://foo.com"
+    #
+    def host=(v)
+      check_host(v)
+      set_host(v)
+      set_userinfo(nil)
+      v
+    end
+
+    # Extract the host part of the Bundler::URI and unwrap brackets for IPv6 addresses.
+    #
+    # This method is the same as Bundler::URI::Generic#host except
+    # brackets for IPv6 (and future IP) addresses are removed.
+    #
+    #   uri = Bundler::URI("http://[::1]/bar")
+    #   uri.hostname      #=> "::1"
+    #   uri.host          #=> "[::1]"
+    #
+    def hostname
+      v = self.host
+      v&.start_with?('[') && v.end_with?(']') ? v[1..-2] : v
+    end
+
+    # Sets the host part of the Bundler::URI as the argument with brackets for IPv6 addresses.
+    #
+    # This method is the same as Bundler::URI::Generic#host= except
+    # the argument can be a bare IPv6 address.
+    #
+    #   uri = Bundler::URI("http://foo/bar")
+    #   uri.hostname = "::1"
+    #   uri.to_s  #=> "http://[::1]/bar"
+    #
+    # If the argument seems to be an IPv6 address,
+    # it is wrapped with brackets.
+    #
+    def hostname=(v)
+      v = "[#{v}]" if !(v&.start_with?('[') && v&.end_with?(']')) && v&.index(':')
+      self.host = v
+    end
+
+    #
+    # Checks the port +v+ component for RFC2396 compliance
+    # and against the +parser+ Regexp for :PORT.
+    #
+    # Can not have a registry or opaque component defined,
+    # with a port component defined.
+    #
+    def check_port(v)
+      return v unless v
+
+      if @opaque
+        raise InvalidURIError,
+          "cannot set port with registry or opaque"
+      elsif !v.kind_of?(Integer) && parser.regexp[:PORT] !~ v
+        raise InvalidComponentError,
+          "bad component(expected port component): #{v.inspect}"
+      end
+
+      return true
+    end
+    private :check_port
+
+    # Protected setter for the port component +v+.
+    #
+    # See also Bundler::URI::Generic.port=.
+    #
+    def set_port(v)
+      v = v.empty? ? nil : v.to_i unless !v || v.kind_of?(Integer)
+      @port = v
+    end
+    protected :set_port
+
+    #
+    # == Args
+    #
+    # +v+::
+    #    String
+    #
+    # == Description
+    #
+    # Public setter for the port component +v+
+    # (with validation).
+    #
+    # See also Bundler::URI::Generic.check_port.
+    #
+    # == Usage
+    #
+    #   require 'bundler/vendor/uri/lib/uri'
+    #
+    #   uri = Bundler::URI.parse("http://my.example.com")
+    #   uri.port = 8080
+    #   uri.to_s  #=> "http://my.example.com:8080"
+    #
+    def port=(v)
+      check_port(v)
+      set_port(v)
+      set_userinfo(nil)
+      port
+    end
+
+    def check_registry(v) # :nodoc:
+      raise InvalidURIError, "cannot set registry"
+    end
+    private :check_registry
+
+    def set_registry(v) # :nodoc:
+      raise InvalidURIError, "cannot set registry"
+    end
+    protected :set_registry
+
+    def registry=(v) # :nodoc:
+      raise InvalidURIError, "cannot set registry"
+    end
+
+    #
+    # Checks the path +v+ component for RFC2396 compliance
+    # and against the +parser+ Regexp
+    # for :ABS_PATH and :REL_PATH.
+    #
+    # Can not have a opaque component defined,
+    # with a path component defined.
+    #
+    def check_path(v)
+      # raise if both hier and opaque are not nil, because:
+      # absoluteURI   = scheme ":" ( hier_part | opaque_part )
+      # hier_part     = ( net_path | abs_path ) [ "?" query ]
+      if v && @opaque
+        raise InvalidURIError,
+          "path conflicts with opaque"
+      end
+
+      # If scheme is ftp, path may be relative.
+      # See RFC 1738 section 3.2.2, and RFC 2396.
+      if @scheme && @scheme != "ftp"
+        if v && v != '' && parser.regexp[:ABS_PATH] !~ v
+          raise InvalidComponentError,
+            "bad component(expected absolute path component): #{v}"
+        end
+      else
+        if v && v != '' && parser.regexp[:ABS_PATH] !~ v &&
+           parser.regexp[:REL_PATH] !~ v
+          raise InvalidComponentError,
+            "bad component(expected relative path component): #{v}"
+        end
+      end
+
+      return true
+    end
+    private :check_path
+
+    # Protected setter for the path component +v+.
+    #
+    # See also Bundler::URI::Generic.path=.
+    #
+    def set_path(v)
+      @path = v
+    end
+    protected :set_path
+
+    #
+    # == Args
+    #
+    # +v+::
+    #    String
+    #
+    # == Description
+    #
+    # Public setter for the path component +v+
+    # (with validation).
+    #
+    # See also Bundler::URI::Generic.check_path.
+    #
+    # == Usage
+    #
+    #   require 'bundler/vendor/uri/lib/uri'
+    #
+    #   uri = Bundler::URI.parse("http://my.example.com/pub/files")
+    #   uri.path = "/faq/"
+    #   uri.to_s  #=> "http://my.example.com/faq/"
+    #
+    def path=(v)
+      check_path(v)
+      set_path(v)
+      v
+    end
+
+    #
+    # == Args
+    #
+    # +v+::
+    #    String
+    #
+    # == Description
+    #
+    # Public setter for the query component +v+.
+    #
+    # == Usage
+    #
+    #   require 'bundler/vendor/uri/lib/uri'
+    #
+    #   uri = Bundler::URI.parse("http://my.example.com/?id=25")
+    #   uri.query = "id=1"
+    #   uri.to_s  #=> "http://my.example.com/?id=1"
+    #
+    def query=(v)
+      return @query = nil unless v
+      raise InvalidURIError, "query conflicts with opaque" if @opaque
+
+      x = v.to_str
+      v = x.dup if x.equal? v
+      v.encode!(Encoding::UTF_8) rescue nil
+      v.delete!("\t\r\n")
+      v.force_encoding(Encoding::ASCII_8BIT)
+      raise InvalidURIError, "invalid percent escape: #{$1}" if /(%\H\H)/n.match(v)
+      v.gsub!(/(?!%\h\h|[!$-&(-;=?-_a-~])./n.freeze){'%%%02X' % $&.ord}
+      v.force_encoding(Encoding::US_ASCII)
+      @query = v
+    end
+
+    #
+    # Checks the opaque +v+ component for RFC2396 compliance and
+    # against the +parser+ Regexp for :OPAQUE.
+    #
+    # Can not have a host, port, user, or path component defined,
+    # with an opaque component defined.
+    #
+    def check_opaque(v)
+      return v unless v
+
+      # raise if both hier and opaque are not nil, because:
+      # absoluteURI   = scheme ":" ( hier_part | opaque_part )
+      # hier_part     = ( net_path | abs_path ) [ "?" query ]
+      if @host || @port || @user || @path  # userinfo = @user + ':' + @password
+        raise InvalidURIError,
+          "cannot set opaque with host, port, userinfo or path"
+      elsif v && parser.regexp[:OPAQUE] !~ v
+        raise InvalidComponentError,
+          "bad component(expected opaque component): #{v}"
+      end
+
+      return true
+    end
+    private :check_opaque
+
+    # Protected setter for the opaque component +v+.
+    #
+    # See also Bundler::URI::Generic.opaque=.
+    #
+    def set_opaque(v)
+      @opaque = v
+    end
+    protected :set_opaque
+
+    #
+    # == Args
+    #
+    # +v+::
+    #    String
+    #
+    # == Description
+    #
+    # Public setter for the opaque component +v+
+    # (with validation).
+    #
+    # See also Bundler::URI::Generic.check_opaque.
+    #
+    def opaque=(v)
+      check_opaque(v)
+      set_opaque(v)
+      v
+    end
+
+    #
+    # Checks the fragment +v+ component against the +parser+ Regexp for :FRAGMENT.
+    #
+    #
+    # == Args
+    #
+    # +v+::
+    #    String
+    #
+    # == Description
+    #
+    # Public setter for the fragment component +v+
+    # (with validation).
+    #
+    # == Usage
+    #
+    #   require 'bundler/vendor/uri/lib/uri'
+    #
+    #   uri = Bundler::URI.parse("http://my.example.com/?id=25#time=1305212049")
+    #   uri.fragment = "time=1305212086"
+    #   uri.to_s  #=> "http://my.example.com/?id=25#time=1305212086"
+    #
+    def fragment=(v)
+      return @fragment = nil unless v
+
+      x = v.to_str
+      v = x.dup if x.equal? v
+      v.encode!(Encoding::UTF_8) rescue nil
+      v.delete!("\t\r\n")
+      v.force_encoding(Encoding::ASCII_8BIT)
+      v.gsub!(/(?!%\h\h|[!-~])./n){'%%%02X' % $&.ord}
+      v.force_encoding(Encoding::US_ASCII)
+      @fragment = v
+    end
+
+    #
+    # Returns true if Bundler::URI is hierarchical.
+    #
+    # == Description
+    #
+    # Bundler::URI has components listed in order of decreasing significance from left to right,
+    # see RFC3986 https://www.rfc-editor.org/rfc/rfc3986 1.2.3.
+    #
+    # == Usage
+    #
+    #   require 'bundler/vendor/uri/lib/uri'
+    #
+    #   uri = Bundler::URI.parse("http://my.example.com/")
+    #   uri.hierarchical?
+    #   #=> true
+    #   uri = Bundler::URI.parse("mailto:joe@example.com")
+    #   uri.hierarchical?
+    #   #=> false
+    #
+    def hierarchical?
+      if @path
+        true
+      else
+        false
+      end
+    end
+
+    #
+    # Returns true if Bundler::URI has a scheme (e.g. http:// or https://) specified.
+    #
+    def absolute?
+      if @scheme
+        true
+      else
+        false
+      end
+    end
+    alias absolute absolute?
+
+    #
+    # Returns true if Bundler::URI does not have a scheme (e.g. http:// or https://) specified.
+    #
+    def relative?
+      !absolute?
+    end
+
+    #
+    # Returns an Array of the path split on '/'.
+    #
+    def split_path(path)
+      path.split("/", -1)
+    end
+    private :split_path
+
+    #
+    # Merges a base path +base+, with relative path +rel+,
+    # returns a modified base path.
+    #
+    def merge_path(base, rel)
+
+      # RFC2396, Section 5.2, 5)
+      # RFC2396, Section 5.2, 6)
+      base_path = split_path(base)
+      rel_path  = split_path(rel)
+
+      # RFC2396, Section 5.2, 6), a)
+      base_path << '' if base_path.last == '..'
+      while i = base_path.index('..')
+        base_path.slice!(i - 1, 2)
+      end
+
+      if (first = rel_path.first) and first.empty?
+        base_path.clear
+        rel_path.shift
+      end
+
+      # RFC2396, Section 5.2, 6), c)
+      # RFC2396, Section 5.2, 6), d)
+      rel_path.push('') if rel_path.last == '.' || rel_path.last == '..'
+      rel_path.delete('.')
+
+      # RFC2396, Section 5.2, 6), e)
+      tmp = []
+      rel_path.each do |x|
+        if x == '..' &&
+            !(tmp.empty? || tmp.last == '..')
+          tmp.pop
+        else
+          tmp << x
+        end
+      end
+
+      add_trailer_slash = !tmp.empty?
+      if base_path.empty?
+        base_path = [''] # keep '/' for root directory
+      elsif add_trailer_slash
+        base_path.pop
+      end
+      while x = tmp.shift
+        if x == '..'
+          # RFC2396, Section 4
+          # a .. or . in an absolute path has no special meaning
+          base_path.pop if base_path.size > 1
+        else
+          # if x == '..'
+          #   valid absolute (but abnormal) path "/../..."
+          # else
+          #   valid absolute path
+          # end
+          base_path << x
+          tmp.each {|t| base_path << t}
+          add_trailer_slash = false
+          break
+        end
+      end
+      base_path.push('') if add_trailer_slash
+
+      return base_path.join('/')
+    end
+    private :merge_path
+
+    #
+    # == Args
+    #
+    # +oth+::
+    #    Bundler::URI or String
+    #
+    # == Description
+    #
+    # Destructive form of #merge.
+    #
+    # == Usage
+    #
+    #   require 'bundler/vendor/uri/lib/uri'
+    #
+    #   uri = Bundler::URI.parse("http://my.example.com")
+    #   uri.merge!("/main.rbx?page=1")
+    #   uri.to_s  # => "http://my.example.com/main.rbx?page=1"
+    #
+    def merge!(oth)
+      t = merge(oth)
+      if self == t
+        nil
+      else
+        replace!(t)
+        self
+      end
+    end
+
+    #
+    # == Args
+    #
+    # +oth+::
+    #    Bundler::URI or String
+    #
+    # == Description
+    #
+    # Merges two URIs.
+    #
+    # == Usage
+    #
+    #   require 'bundler/vendor/uri/lib/uri'
+    #
+    #   uri = Bundler::URI.parse("http://my.example.com")
+    #   uri.merge("/main.rbx?page=1")
+    #   # => "http://my.example.com/main.rbx?page=1"
+    #
+    def merge(oth)
+      rel = parser.__send__(:convert_to_uri, oth)
+
+      if rel.absolute?
+        #raise BadURIError, "both Bundler::URI are absolute" if absolute?
+        # hmm... should return oth for usability?
+        return rel
+      end
+
+      unless self.absolute?
+        raise BadURIError, "both Bundler::URI are relative"
+      end
+
+      base = self.dup
+
+      authority = rel.authority
+
+      # RFC2396, Section 5.2, 2)
+      if (rel.path.nil? || rel.path.empty?) && !authority && !rel.query
+        base.fragment=(rel.fragment) if rel.fragment
+        return base
+      end
+
+      base.query = nil
+      base.fragment=(nil)
+
+      # RFC2396, Section 5.2, 4)
+      if authority
+        base.set_authority(*authority)
+        base.set_path(rel.path)
+      elsif base.path && rel.path
+        base.set_path(merge_path(base.path, rel.path))
+      end
+
+      # RFC2396, Section 5.2, 7)
+      base.query = rel.query       if rel.query
+      base.fragment=(rel.fragment) if rel.fragment
+
+      return base
+    end # merge
+    alias + merge
+
+    # :stopdoc:
+    def route_from_path(src, dst)
+      case dst
+      when src
+        # RFC2396, Section 4.2
+        return ''
+      when %r{(?:\A|/)\.\.?(?:/|\z)}
+        # dst has abnormal absolute path,
+        # like "/./", "/../", "/x/../", ...
+        return dst.dup
+      end
+
+      src_path = src.scan(%r{[^/]*/})
+      dst_path = dst.scan(%r{[^/]*/?})
+
+      # discard same parts
+      while !dst_path.empty? && dst_path.first == src_path.first
+        src_path.shift
+        dst_path.shift
+      end
+
+      tmp = dst_path.join
+
+      # calculate
+      if src_path.empty?
+        if tmp.empty?
+          return './'
+        elsif dst_path.first.include?(':') # (see RFC2396 Section 5)
+          return './' + tmp
+        else
+          return tmp
+        end
+      end
+
+      return '../' * src_path.size + tmp
+    end
+    private :route_from_path
+    # :startdoc:
+
+    # :stopdoc:
+    def route_from0(oth)
+      oth = parser.__send__(:convert_to_uri, oth)
+      if self.relative?
+        raise BadURIError,
+          "relative Bundler::URI: #{self}"
+      end
+      if oth.relative?
+        raise BadURIError,
+          "relative Bundler::URI: #{oth}"
+      end
+
+      if self.scheme != oth.scheme
+        return self, self.dup
+      end
+      rel = Bundler::URI::Generic.new(nil, # it is relative Bundler::URI
+                             self.userinfo, self.host, self.port,
+                             nil, self.path, self.opaque,
+                             self.query, self.fragment, parser)
+
+      if rel.userinfo != oth.userinfo ||
+          rel.host.to_s.downcase != oth.host.to_s.downcase ||
+          rel.port != oth.port
+
+        if self.userinfo.nil? && self.host.nil?
+          return self, self.dup
+        end
+
+        rel.set_port(nil) if rel.port == oth.default_port
+        return rel, rel
+      end
+      rel.set_userinfo(nil)
+      rel.set_host(nil)
+      rel.set_port(nil)
+
+      if rel.path && rel.path == oth.path
+        rel.set_path('')
+        rel.query = nil if rel.query == oth.query
+        return rel, rel
+      elsif rel.opaque && rel.opaque == oth.opaque
+        rel.set_opaque('')
+        rel.query = nil if rel.query == oth.query
+        return rel, rel
+      end
+
+      # you can modify `rel', but cannot `oth'.
+      return oth, rel
+    end
+    private :route_from0
+    # :startdoc:
+
+    #
+    # == Args
+    #
+    # +oth+::
+    #    Bundler::URI or String
+    #
+    # == Description
+    #
+    # Calculates relative path from oth to self.
+    #
+    # == Usage
+    #
+    #   require 'bundler/vendor/uri/lib/uri'
+    #
+    #   uri = Bundler::URI.parse('http://my.example.com/main.rbx?page=1')
+    #   uri.route_from('http://my.example.com')
+    #   #=> #<Bundler::URI::Generic /main.rbx?page=1>
+    #
+    def route_from(oth)
+      # you can modify `rel', but cannot `oth'.
+      begin
+        oth, rel = route_from0(oth)
+      rescue
+        raise $!.class, $!.message
+      end
+      if oth == rel
+        return rel
+      end
+
+      rel.set_path(route_from_path(oth.path, self.path))
+      if rel.path == './' && self.query
+        # "./?foo" -> "?foo"
+        rel.set_path('')
+      end
+
+      return rel
+    end
+
+    alias - route_from
+
+    #
+    # == Args
+    #
+    # +oth+::
+    #    Bundler::URI or String
+    #
+    # == Description
+    #
+    # Calculates relative path to oth from self.
+    #
+    # == Usage
+    #
+    #   require 'bundler/vendor/uri/lib/uri'
+    #
+    #   uri = Bundler::URI.parse('http://my.example.com')
+    #   uri.route_to('http://my.example.com/main.rbx?page=1')
+    #   #=> #<Bundler::URI::Generic /main.rbx?page=1>
+    #
+    def route_to(oth)
+      parser.__send__(:convert_to_uri, oth).route_from(self)
+    end
+
+    #
+    # Returns normalized Bundler::URI.
+    #
+    #   require 'bundler/vendor/uri/lib/uri'
+    #
+    #   Bundler::URI("HTTP://my.EXAMPLE.com").normalize
+    #   #=> #<Bundler::URI::HTTP http://my.example.com/>
+    #
+    # Normalization here means:
+    #
+    # * scheme and host are converted to lowercase,
+    # * an empty path component is set to "/".
+    #
+    def normalize
+      uri = dup
+      uri.normalize!
+      uri
+    end
+
+    #
+    # Destructive version of #normalize.
+    #
+    def normalize!
+      if path&.empty?
+        set_path('/')
+      end
+      if scheme && scheme != scheme.downcase
+        set_scheme(self.scheme.downcase)
+      end
+      if host && host != host.downcase
+        set_host(self.host.downcase)
+      end
+    end
+
+    #
+    # Constructs String from Bundler::URI.
+    #
+    def to_s
+      str = ''.dup
+      if @scheme
+        str << @scheme
+        str << ':'
+      end
+
+      if @opaque
+        str << @opaque
+      else
+        if @host || %w[file postgres].include?(@scheme)
+          str << '//'
+        end
+        if self.userinfo
+          str << self.userinfo
+          str << '@'
+        end
+        if @host
+          str << @host
+        end
+        if @port && @port != self.default_port
+          str << ':'
+          str << @port.to_s
+        end
+        if (@host || @port) && !@path.empty? && !@path.start_with?('/')
+          str << '/'
+        end
+        str << @path
+        if @query
+          str << '?'
+          str << @query
+        end
+      end
+      if @fragment
+        str << '#'
+        str << @fragment
+      end
+      str
+    end
+    alias to_str to_s
+
+    #
+    # Compares two URIs.
+    #
+    def ==(oth)
+      if self.class == oth.class
+        self.normalize.component_ary == oth.normalize.component_ary
+      else
+        false
+      end
+    end
+
+    # Returns the hash value.
+    def hash
+      self.component_ary.hash
+    end
+
+    # Compares with _oth_ for Hash.
+    def eql?(oth)
+      self.class == oth.class &&
+      parser == oth.parser &&
+      self.component_ary.eql?(oth.component_ary)
+    end
+
+    # Returns an Array of the components defined from the COMPONENT Array.
+    def component_ary
+      component.collect do |x|
+        self.__send__(x)
+      end
+    end
+    protected :component_ary
+
+    # == Args
+    #
+    # +components+::
+    #    Multiple Symbol arguments defined in Bundler::URI::HTTP.
+    #
+    # == Description
+    #
+    # Selects specified components from Bundler::URI.
+    #
+    # == Usage
+    #
+    #   require 'bundler/vendor/uri/lib/uri'
+    #
+    #   uri = Bundler::URI.parse('http://myuser:mypass@my.example.com/test.rbx')
+    #   uri.select(:userinfo, :host, :path)
+    #   # => ["myuser:mypass", "my.example.com", "/test.rbx"]
+    #
+    def select(*components)
+      components.collect do |c|
+        if component.include?(c)
+          self.__send__(c)
+        else
+          raise ArgumentError,
+            "expected of components of #{self.class} (#{self.class.component.join(', ')})"
+        end
+      end
+    end
+
+    def inspect # :nodoc:
+      "#<#{self.class} #{self}>"
+    end
+
+    #
+    # == Args
+    #
+    # +v+::
+    #    Bundler::URI or String
+    #
+    # == Description
+    #
+    # Attempts to parse other Bundler::URI +oth+,
+    # returns [parsed_oth, self].
+    #
+    # == Usage
+    #
+    #   require 'bundler/vendor/uri/lib/uri'
+    #
+    #   uri = Bundler::URI.parse("http://my.example.com")
+    #   uri.coerce("http://foo.com")
+    #   #=> [#<Bundler::URI::HTTP http://foo.com>, #<Bundler::URI::HTTP http://my.example.com>]
+    #
+    def coerce(oth)
+      case oth
+      when String
+        oth = parser.parse(oth)
+      else
+        super
+      end
+
+      return oth, self
+    end
+
+    # Returns a proxy Bundler::URI.
+    # The proxy Bundler::URI is obtained from environment variables such as http_proxy,
+    # ftp_proxy, no_proxy, etc.
+    # If there is no proper proxy, nil is returned.
+    #
+    # If the optional parameter +env+ is specified, it is used instead of ENV.
+    #
+    # Note that capitalized variables (HTTP_PROXY, FTP_PROXY, NO_PROXY, etc.)
+    # are examined, too.
+    #
+    # But http_proxy and HTTP_PROXY is treated specially under CGI environment.
+    # It's because HTTP_PROXY may be set by Proxy: header.
+    # So HTTP_PROXY is not used.
+    # http_proxy is not used too if the variable is case insensitive.
+    # CGI_HTTP_PROXY can be used instead.
+    def find_proxy(env=ENV)
+      raise BadURIError, "relative Bundler::URI: #{self}" if self.relative?
+      name = self.scheme.downcase + '_proxy'
+      proxy_uri = nil
+      if name == 'http_proxy' && env.include?('REQUEST_METHOD') # CGI?
+        # HTTP_PROXY conflicts with *_proxy for proxy settings and
+        # HTTP_* for header information in CGI.
+        # So it should be careful to use it.
+        pairs = env.reject {|k, v| /\Ahttp_proxy\z/i !~ k }
+        case pairs.length
+        when 0 # no proxy setting anyway.
+          proxy_uri = nil
+        when 1
+          k, _ = pairs.shift
+          if k == 'http_proxy' && env[k.upcase] == nil
+            # http_proxy is safe to use because ENV is case sensitive.
+            proxy_uri = env[name]
+          else
+            proxy_uri = nil
+          end
+        else # http_proxy is safe to use because ENV is case sensitive.
+          proxy_uri = env.to_hash[name]
+        end
+        if !proxy_uri
+          # Use CGI_HTTP_PROXY.  cf. libwww-perl.
+          proxy_uri = env["CGI_#{name.upcase}"]
+        end
+      elsif name == 'http_proxy'
+        if RUBY_ENGINE == 'jruby' && p_addr = ENV_JAVA['http.proxyHost']
+          p_port = ENV_JAVA['http.proxyPort']
+          if p_user = ENV_JAVA['http.proxyUser']
+            p_pass = ENV_JAVA['http.proxyPass']
+            proxy_uri = "http://#{p_user}:#{p_pass}@#{p_addr}:#{p_port}"
+          else
+            proxy_uri = "http://#{p_addr}:#{p_port}"
+          end
+        else
+          unless proxy_uri = env[name]
+            if proxy_uri = env[name.upcase]
+              warn 'The environment variable HTTP_PROXY is discouraged.  Please use http_proxy instead.', uplevel: 1
+            end
+          end
+        end
+      else
+        proxy_uri = env[name] || env[name.upcase]
+      end
+
+      if proxy_uri.nil? || proxy_uri.empty?
+        return nil
+      end
+
+      if self.hostname
+        begin
+          addr = IPSocket.getaddress(self.hostname)
+          return nil if /\A127\.|\A::1\z/ =~ addr
+        rescue SocketError
+        end
+      end
+
+      name = 'no_proxy'
+      if no_proxy = env[name] || env[name.upcase]
+        return nil unless Bundler::URI::Generic.use_proxy?(self.hostname, addr, self.port, no_proxy)
+      end
+      Bundler::URI.parse(proxy_uri)
+    end
+
+    def self.use_proxy?(hostname, addr, port, no_proxy) # :nodoc:
+      hostname = hostname.downcase
+      dothostname = ".#{hostname}"
+      no_proxy.scan(/([^:,\s]+)(?::(\d+))?/) {|p_host, p_port|
+        if !p_port || port == p_port.to_i
+          if p_host.start_with?('.')
+            return false if hostname.end_with?(p_host.downcase)
+          else
+            return false if dothostname.end_with?(".#{p_host.downcase}")
+          end
+          if addr
+            begin
+              return false if IPAddr.new(p_host).include?(addr)
+            rescue IPAddr::InvalidAddressError
+              next
+            end
+          end
+        end
+      }
+      true
+    end
+  end
+end
diff --git a/lib/bundler/vendor/uri/lib/uri/http.rb b/lib/bundler/vendor/uri/lib/uri/http.rb
new file mode 100644
index 0000000000..9b217ee266
--- /dev/null
+++ b/lib/bundler/vendor/uri/lib/uri/http.rb
@@ -0,0 +1,137 @@
+# frozen_string_literal: false
+# = uri/http.rb
+#
+# Author:: Akira Yamada <akira@ruby-lang.org>
+# License:: You can redistribute it and/or modify it under the same term as Ruby.
+#
+# See Bundler::URI for general documentation
+#
+
+require_relative 'generic'
+
+module Bundler::URI
+
+  #
+  # The syntax of HTTP URIs is defined in RFC1738 section 3.3.
+  #
+  # Note that the Ruby Bundler::URI library allows HTTP URLs containing usernames and
+  # passwords. This is not legal as per the RFC, but used to be
+  # supported in Internet Explorer 5 and 6, before the MS04-004 security
+  # update. See <URL:http://support.microsoft.com/kb/834489>.
+  #
+  class HTTP < Generic
+    # A Default port of 80 for Bundler::URI::HTTP.
+    DEFAULT_PORT = 80
+
+    # An Array of the available components for Bundler::URI::HTTP.
+    COMPONENT = %i[
+      scheme
+      userinfo host port
+      path
+      query
+      fragment
+    ].freeze
+
+    #
+    # == Description
+    #
+    # Creates a new Bundler::URI::HTTP object from components, with syntax checking.
+    #
+    # The components accepted are userinfo, host, port, path, query, and
+    # fragment.
+    #
+    # The components should be provided either as an Array, or as a Hash
+    # with keys formed by preceding the component names with a colon.
+    #
+    # If an Array is used, the components must be passed in the
+    # order <code>[userinfo, host, port, path, query, fragment]</code>.
+    #
+    # Example:
+    #
+    #     uri = Bundler::URI::HTTP.build(host: 'www.example.com', path: '/foo/bar')
+    #
+    #     uri = Bundler::URI::HTTP.build([nil, "www.example.com", nil, "/path",
+    #       "query", 'fragment'])
+    #
+    # Currently, if passed userinfo components this method generates
+    # invalid HTTP URIs as per RFC 1738.
+    #
+    def self.build(args)
+      tmp = Util.make_components_hash(self, args)
+      super(tmp)
+    end
+
+    # Do not allow empty host names, as they are not allowed by RFC 3986.
+    def check_host(v)
+      ret = super
+
+      if ret && v.empty?
+        raise InvalidComponentError,
+          "bad component(expected host component): #{v}"
+      end
+
+      ret
+    end
+
+    #
+    # == Description
+    #
+    # Returns the full path for an HTTP request, as required by Net::HTTP::Get.
+    #
+    # If the Bundler::URI contains a query, the full path is Bundler::URI#path + '?' + Bundler::URI#query.
+    # Otherwise, the path is simply Bundler::URI#path.
+    #
+    # Example:
+    #
+    #     uri = Bundler::URI::HTTP.build(path: '/foo/bar', query: 'test=true')
+    #     uri.request_uri #  => "/foo/bar?test=true"
+    #
+    def request_uri
+      return unless @path
+
+      url = @query ? "#@path?#@query" : @path.dup
+      url.start_with?(?/.freeze) ? url : ?/ + url
+    end
+
+    #
+    # == Description
+    #
+    # Returns the authority for an HTTP uri, as defined in
+    # https://www.rfc-editor.org/rfc/rfc3986#section-3.2.
+    #
+    #
+    # Example:
+    #
+    #     Bundler::URI::HTTP.build(host: 'www.example.com', path: '/foo/bar').authority #=> "www.example.com"
+    #     Bundler::URI::HTTP.build(host: 'www.example.com', port: 8000, path: '/foo/bar').authority #=> "www.example.com:8000"
+    #     Bundler::URI::HTTP.build(host: 'www.example.com', port: 80, path: '/foo/bar').authority #=> "www.example.com"
+    #
+    def authority
+      if port == default_port
+        host
+      else
+        "#{host}:#{port}"
+      end
+    end
+
+    #
+    # == Description
+    #
+    # Returns the origin for an HTTP uri, as defined in
+    # https://www.rfc-editor.org/rfc/rfc6454.
+    #
+    #
+    # Example:
+    #
+    #     Bundler::URI::HTTP.build(host: 'www.example.com', path: '/foo/bar').origin #=> "http://www.example.com"
+    #     Bundler::URI::HTTP.build(host: 'www.example.com', port: 8000, path: '/foo/bar').origin #=> "http://www.example.com:8000"
+    #     Bundler::URI::HTTP.build(host: 'www.example.com', port: 80, path: '/foo/bar').origin #=> "http://www.example.com"
+    #     Bundler::URI::HTTPS.build(host: 'www.example.com', path: '/foo/bar').origin #=> "https://www.example.com"
+    #
+    def origin
+      "#{scheme}://#{authority}"
+    end
+  end
+
+  register_scheme 'HTTP', HTTP
+end
diff --git a/lib/bundler/vendor/uri/lib/uri/https.rb b/lib/bundler/vendor/uri/lib/uri/https.rb
new file mode 100644
index 0000000000..e4556e3ecb
--- /dev/null
+++ b/lib/bundler/vendor/uri/lib/uri/https.rb
@@ -0,0 +1,23 @@
+# frozen_string_literal: false
+# = uri/https.rb
+#
+# Author:: Akira Yamada <akira@ruby-lang.org>
+# License:: You can redistribute it and/or modify it under the same term as Ruby.
+#
+# See Bundler::URI for general documentation
+#
+
+require_relative 'http'
+
+module Bundler::URI
+
+  # The default port for HTTPS URIs is 443, and the scheme is 'https:' rather
+  # than 'http:'. Other than that, HTTPS URIs are identical to HTTP URIs;
+  # see Bundler::URI::HTTP.
+  class HTTPS < HTTP
+    # A Default port of 443 for Bundler::URI::HTTPS
+    DEFAULT_PORT = 443
+  end
+
+  register_scheme 'HTTPS', HTTPS
+end
diff --git a/lib/bundler/vendor/uri/lib/uri/ldap.rb b/lib/bundler/vendor/uri/lib/uri/ldap.rb
new file mode 100644
index 0000000000..9811b6e2f5
--- /dev/null
+++ b/lib/bundler/vendor/uri/lib/uri/ldap.rb
@@ -0,0 +1,261 @@
+# frozen_string_literal: false
+# = uri/ldap.rb
+#
+# Author::
+#  Takaaki Tateishi <ttate@jaist.ac.jp>
+#  Akira Yamada <akira@ruby-lang.org>
+# License::
+#   Bundler::URI::LDAP is copyrighted free software by Takaaki Tateishi and Akira Yamada.
+#   You can redistribute it and/or modify it under the same term as Ruby.
+#
+# See Bundler::URI for general documentation
+#
+
+require_relative 'generic'
+
+module Bundler::URI
+
+  #
+  # LDAP Bundler::URI SCHEMA (described in RFC2255).
+  #--
+  # ldap://<host>/<dn>[?<attrs>[?<scope>[?<filter>[?<extensions>]]]]
+  #++
+  class LDAP < Generic
+
+    # A Default port of 389 for Bundler::URI::LDAP.
+    DEFAULT_PORT = 389
+
+    # An Array of the available components for Bundler::URI::LDAP.
+    COMPONENT = [
+      :scheme,
+      :host, :port,
+      :dn,
+      :attributes,
+      :scope,
+      :filter,
+      :extensions,
+    ].freeze
+
+    # Scopes available for the starting point.
+    #
+    # * SCOPE_BASE - the Base DN
+    # * SCOPE_ONE  - one level under the Base DN, not including the base DN and
+    #   not including any entries under this
+    # * SCOPE_SUB  - subtrees, all entries at all levels
+    #
+    SCOPE = [
+      SCOPE_ONE = 'one',
+      SCOPE_SUB = 'sub',
+      SCOPE_BASE = 'base',
+    ].freeze
+
+    #
+    # == Description
+    #
+    # Creates a new Bundler::URI::LDAP object from components, with syntax checking.
+    #
+    # The components accepted are host, port, dn, attributes,
+    # scope, filter, and extensions.
+    #
+    # The components should be provided either as an Array, or as a Hash
+    # with keys formed by preceding the component names with a colon.
+    #
+    # If an Array is used, the components must be passed in the
+    # order <code>[host, port, dn, attributes, scope, filter, extensions]</code>.
+    #
+    # Example:
+    #
+    #     uri = Bundler::URI::LDAP.build({:host => 'ldap.example.com',
+    #       :dn => '/dc=example'})
+    #
+    #     uri = Bundler::URI::LDAP.build(["ldap.example.com", nil,
+    #       "/dc=example;dc=com", "query", nil, nil, nil])
+    #
+    def self.build(args)
+      tmp = Util::make_components_hash(self, args)
+
+      if tmp[:dn]
+        tmp[:path] = tmp[:dn]
+      end
+
+      query = []
+      [:extensions, :filter, :scope, :attributes].collect do |x|
+        next if !tmp[x] && query.size == 0
+        query.unshift(tmp[x])
+      end
+
+      tmp[:query] = query.join('?')
+
+      return super(tmp)
+    end
+
+    #
+    # == Description
+    #
+    # Creates a new Bundler::URI::LDAP object from generic Bundler::URI components as per
+    # RFC 2396. No LDAP-specific syntax checking is performed.
+    #
+    # Arguments are +scheme+, +userinfo+, +host+, +port+, +registry+, +path+,
+    # +opaque+, +query+, and +fragment+, in that order.
+    #
+    # Example:
+    #
+    #     uri = Bundler::URI::LDAP.new("ldap", nil, "ldap.example.com", nil, nil,
+    #       "/dc=example;dc=com", nil, "query", nil)
+    #
+    # See also Bundler::URI::Generic.new.
+    #
+    def initialize(*arg)
+      super(*arg)
+
+      if @fragment
+        raise InvalidURIError, 'bad LDAP URL'
+      end
+
+      parse_dn
+      parse_query
+    end
+
+    # Private method to cleanup +dn+ from using the +path+ component attribute.
+    def parse_dn
+      raise InvalidURIError, 'bad LDAP URL' unless @path
+      @dn = @path[1..-1]
+    end
+    private :parse_dn
+
+    # Private method to cleanup +attributes+, +scope+, +filter+, and +extensions+
+    # from using the +query+ component attribute.
+    def parse_query
+      @attributes = nil
+      @scope      = nil
+      @filter     = nil
+      @extensions = nil
+
+      if @query
+        attrs, scope, filter, extensions = @query.split('?')
+
+        @attributes = attrs if attrs && attrs.size > 0
+        @scope      = scope if scope && scope.size > 0
+        @filter     = filter if filter && filter.size > 0
+        @extensions = extensions if extensions && extensions.size > 0
+      end
+    end
+    private :parse_query
+
+    # Private method to assemble +query+ from +attributes+, +scope+, +filter+, and +extensions+.
+    def build_path_query
+      @path = '/' + @dn
+
+      query = []
+      [@extensions, @filter, @scope, @attributes].each do |x|
+        next if !x && query.size == 0
+        query.unshift(x)
+      end
+      @query = query.join('?')
+    end
+    private :build_path_query
+
+    # Returns dn.
+    def dn
+      @dn
+    end
+
+    # Private setter for dn +val+.
+    def set_dn(val)
+      @dn = val
+      build_path_query
+      @dn
+    end
+    protected :set_dn
+
+    # Setter for dn +val+.
+    def dn=(val)
+      set_dn(val)
+      val
+    end
+
+    # Returns attributes.
+    def attributes
+      @attributes
+    end
+
+    # Private setter for attributes +val+.
+    def set_attributes(val)
+      @attributes = val
+      build_path_query
+      @attributes
+    end
+    protected :set_attributes
+
+    # Setter for attributes +val+.
+    def attributes=(val)
+      set_attributes(val)
+      val
+    end
+
+    # Returns scope.
+    def scope
+      @scope
+    end
+
+    # Private setter for scope +val+.
+    def set_scope(val)
+      @scope = val
+      build_path_query
+      @scope
+    end
+    protected :set_scope
+
+    # Setter for scope +val+.
+    def scope=(val)
+      set_scope(val)
+      val
+    end
+
+    # Returns filter.
+    def filter
+      @filter
+    end
+
+    # Private setter for filter +val+.
+    def set_filter(val)
+      @filter = val
+      build_path_query
+      @filter
+    end
+    protected :set_filter
+
+    # Setter for filter +val+.
+    def filter=(val)
+      set_filter(val)
+      val
+    end
+
+    # Returns extensions.
+    def extensions
+      @extensions
+    end
+
+    # Private setter for extensions +val+.
+    def set_extensions(val)
+      @extensions = val
+      build_path_query
+      @extensions
+    end
+    protected :set_extensions
+
+    # Setter for extensions +val+.
+    def extensions=(val)
+      set_extensions(val)
+      val
+    end
+
+    # Checks if Bundler::URI has a path.
+    # For Bundler::URI::LDAP this will return +false+.
+    def hierarchical?
+      false
+    end
+  end
+
+  register_scheme 'LDAP', LDAP
+end
diff --git a/lib/bundler/vendor/uri/lib/uri/ldaps.rb b/lib/bundler/vendor/uri/lib/uri/ldaps.rb
new file mode 100644
index 0000000000..c786168450
--- /dev/null
+++ b/lib/bundler/vendor/uri/lib/uri/ldaps.rb
@@ -0,0 +1,22 @@
+# frozen_string_literal: false
+# = uri/ldap.rb
+#
+# License:: You can redistribute it and/or modify it under the same term as Ruby.
+#
+# See Bundler::URI for general documentation
+#
+
+require_relative 'ldap'
+
+module Bundler::URI
+
+  # The default port for LDAPS URIs is 636, and the scheme is 'ldaps:' rather
+  # than 'ldap:'. Other than that, LDAPS URIs are identical to LDAP URIs;
+  # see Bundler::URI::LDAP.
+  class LDAPS < LDAP
+    # A Default port of 636 for Bundler::URI::LDAPS
+    DEFAULT_PORT = 636
+  end
+
+  register_scheme 'LDAPS', LDAPS
+end
diff --git a/lib/bundler/vendor/uri/lib/uri/mailto.rb b/lib/bundler/vendor/uri/lib/uri/mailto.rb
new file mode 100644
index 0000000000..ff2e30be86
--- /dev/null
+++ b/lib/bundler/vendor/uri/lib/uri/mailto.rb
@@ -0,0 +1,293 @@
+# frozen_string_literal: false
+# = uri/mailto.rb
+#
+# Author:: Akira Yamada <akira@ruby-lang.org>
+# License:: You can redistribute it and/or modify it under the same term as Ruby.
+#
+# See Bundler::URI for general documentation
+#
+
+require_relative 'generic'
+
+module Bundler::URI
+
+  #
+  # RFC6068, the mailto URL scheme.
+  #
+  class MailTo < Generic
+    include RFC2396_REGEXP
+
+    # A Default port of nil for Bundler::URI::MailTo.
+    DEFAULT_PORT = nil
+
+    # An Array of the available components for Bundler::URI::MailTo.
+    COMPONENT = [ :scheme, :to, :headers ].freeze
+
+    # :stopdoc:
+    #  "hname" and "hvalue" are encodings of an RFC 822 header name and
+    #  value, respectively. As with "to", all URL reserved characters must
+    #  be encoded.
+    #
+    #  "#mailbox" is as specified in RFC 822 [RFC822]. This means that it
+    #  consists of zero or more comma-separated mail addresses, possibly
+    #  including "phrase" and "comment" components. Note that all URL
+    #  reserved characters in "to" must be encoded: in particular,
+    #  parentheses, commas, and the percent sign ("%"), which commonly occur
+    #  in the "mailbox" syntax.
+    #
+    #  Within mailto URLs, the characters "?", "=", "&" are reserved.
+
+    # ; RFC 6068
+    # hfields      = "?" hfield *( "&" hfield )
+    # hfield       = hfname "=" hfvalue
+    # hfname       = *qchar
+    # hfvalue      = *qchar
+    # qchar        = unreserved / pct-encoded / some-delims
+    # some-delims  = "!" / "$" / "'" / "(" / ")" / "*"
+    #              / "+" / "," / ";" / ":" / "@"
+    #
+    # ; RFC3986
+    # unreserved   = ALPHA / DIGIT / "-" / "." / "_" / "~"
+    # pct-encoded  = "%" HEXDIG HEXDIG
+    HEADER_REGEXP  = /\A(?<hfield>(?:%\h\h|[!$'-.0-;@-Z_a-z~])*=(?:%\h\h|[!$'-.0-;@-Z_a-z~])*)(?:&\g<hfield>)*\z/
+    # practical regexp for email address
+    # https://html.spec.whatwg.org/multipage/input.html#valid-e-mail-address
+    EMAIL_REGEXP = /\A[a-zA-Z0-9.!\#$%&'*+\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*\z/
+    # :startdoc:
+
+    #
+    # == Description
+    #
+    # Creates a new Bundler::URI::MailTo object from components, with syntax checking.
+    #
+    # Components can be provided as an Array or Hash. If an Array is used,
+    # the components must be supplied as <code>[to, headers]</code>.
+    #
+    # If a Hash is used, the keys are the component names preceded by colons.
+    #
+    # The headers can be supplied as a pre-encoded string, such as
+    # <code>"subject=subscribe&cc=address"</code>, or as an Array of Arrays
+    # like <code>[['subject', 'subscribe'], ['cc', 'address']]</code>.
+    #
+    # Examples:
+    #
+    #    require 'bundler/vendor/uri/lib/uri'
+    #
+    #    m1 = Bundler::URI::MailTo.build(['joe@example.com', 'subject=Ruby'])
+    #    m1.to_s  # => "mailto:joe@example.com?subject=Ruby"
+    #
+    #    m2 = Bundler::URI::MailTo.build(['john@example.com', [['Subject', 'Ruby'], ['Cc', 'jack@example.com']]])
+    #    m2.to_s  # => "mailto:john@example.com?Subject=Ruby&Cc=jack@example.com"
+    #
+    #    m3 = Bundler::URI::MailTo.build({:to => 'listman@example.com', :headers => [['subject', 'subscribe']]})
+    #    m3.to_s  # => "mailto:listman@example.com?subject=subscribe"
+    #
+    def self.build(args)
+      tmp = Util.make_components_hash(self, args)
+
+      case tmp[:to]
+      when Array
+        tmp[:opaque] = tmp[:to].join(',')
+      when String
+        tmp[:opaque] = tmp[:to].dup
+      else
+        tmp[:opaque] = ''
+      end
+
+      if tmp[:headers]
+        query =
+          case tmp[:headers]
+          when Array
+            tmp[:headers].collect { |x|
+              if x.kind_of?(Array)
+                x[0] + '=' + x[1..-1].join
+              else
+                x.to_s
+              end
+            }.join('&')
+          when Hash
+            tmp[:headers].collect { |h,v|
+              h + '=' + v
+            }.join('&')
+          else
+            tmp[:headers].to_s
+          end
+        unless query.empty?
+          tmp[:opaque] << '?' << query
+        end
+      end
+
+      super(tmp)
+    end
+
+    #
+    # == Description
+    #
+    # Creates a new Bundler::URI::MailTo object from generic URL components with
+    # no syntax checking.
+    #
+    # This method is usually called from Bundler::URI::parse, which checks
+    # the validity of each component.
+    #
+    def initialize(*arg)
+      super(*arg)
+
+      @to = nil
+      @headers = []
+
+      # The RFC3986 parser does not normally populate opaque
+      @opaque = "?#{@query}" if @query && !@opaque
+
+      unless @opaque
+        raise InvalidComponentError,
+          "missing opaque part for mailto URL"
+      end
+      to, header = @opaque.split('?', 2)
+      # allow semicolon as a addr-spec separator
+      # http://support.microsoft.com/kb/820868
+      unless /\A(?:[^@,;]+@[^@,;]+(?:\z|[,;]))*\z/ =~ to
+        raise InvalidComponentError,
+          "unrecognised opaque part for mailtoURL: #{@opaque}"
+      end
+
+      if arg[10] # arg_check
+        self.to = to
+        self.headers = header
+      else
+        set_to(to)
+        set_headers(header)
+      end
+    end
+
+    # The primary e-mail address of the URL, as a String.
+    attr_reader :to
+
+    # E-mail headers set by the URL, as an Array of Arrays.
+    attr_reader :headers
+
+    # Checks the to +v+ component.
+    def check_to(v)
+      return true unless v
+      return true if v.size == 0
+
+      v.split(/[,;]/).each do |addr|
+        # check url safety as path-rootless
+        if /\A(?:%\h\h|[!$&-.0-;=@-Z_a-z~])*\z/ !~ addr
+          raise InvalidComponentError,
+            "an address in 'to' is invalid as Bundler::URI #{addr.dump}"
+        end
+
+        # check addr-spec
+        # don't s/\+/ /g
+        addr.gsub!(/%\h\h/, Bundler::URI::TBLDECWWWCOMP_)
+        if EMAIL_REGEXP !~ addr
+          raise InvalidComponentError,
+            "an address in 'to' is invalid as uri-escaped addr-spec #{addr.dump}"
+        end
+      end
+
+      true
+    end
+    private :check_to
+
+    # Private setter for to +v+.
+    def set_to(v)
+      @to = v
+    end
+    protected :set_to
+
+    # Setter for to +v+.
+    def to=(v)
+      check_to(v)
+      set_to(v)
+      v
+    end
+
+    # Checks the headers +v+ component against either
+    # * HEADER_REGEXP
+    def check_headers(v)
+      return true unless v
+      return true if v.size == 0
+      if HEADER_REGEXP !~ v
+        raise InvalidComponentError,
+          "bad component(expected opaque component): #{v}"
+      end
+
+      true
+    end
+    private :check_headers
+
+    # Private setter for headers +v+.
+    def set_headers(v)
+      @headers = []
+      if v
+        v.split('&').each do |x|
+          @headers << x.split(/=/, 2)
+        end
+      end
+    end
+    protected :set_headers
+
+    # Setter for headers +v+.
+    def headers=(v)
+      check_headers(v)
+      set_headers(v)
+      v
+    end
+
+    # Constructs String from Bundler::URI.
+    def to_s
+      @scheme + ':' +
+        if @to
+          @to
+        else
+          ''
+        end +
+        if @headers.size > 0
+          '?' + @headers.collect{|x| x.join('=')}.join('&')
+        else
+          ''
+        end +
+        if @fragment
+          '#' + @fragment
+        else
+          ''
+        end
+    end
+
+    # Returns the RFC822 e-mail text equivalent of the URL, as a String.
+    #
+    # Example:
+    #
+    #   require 'bundler/vendor/uri/lib/uri'
+    #
+    #   uri = Bundler::URI.parse("mailto:ruby-list@ruby-lang.org?Subject=subscribe&cc=myaddr")
+    #   uri.to_mailtext
+    #   # => "To: ruby-list@ruby-lang.org\nSubject: subscribe\nCc: myaddr\n\n\n"
+    #
+    def to_mailtext
+      to = Bundler::URI.decode_www_form_component(@to)
+      head = ''
+      body = ''
+      @headers.each do |x|
+        case x[0]
+        when 'body'
+          body = Bundler::URI.decode_www_form_component(x[1])
+        when 'to'
+          to << ', ' + Bundler::URI.decode_www_form_component(x[1])
+        else
+          head << Bundler::URI.decode_www_form_component(x[0]).capitalize + ': ' +
+            Bundler::URI.decode_www_form_component(x[1])  + "\n"
+        end
+      end
+
+      "To: #{to}
+#{head}
+#{body}
+"
+    end
+    alias to_rfc822text to_mailtext
+  end
+
+  register_scheme 'MAILTO', MailTo
+end
diff --git a/lib/bundler/vendor/uri/lib/uri/rfc2396_parser.rb b/lib/bundler/vendor/uri/lib/uri/rfc2396_parser.rb
new file mode 100644
index 0000000000..522113fe67
--- /dev/null
+++ b/lib/bundler/vendor/uri/lib/uri/rfc2396_parser.rb
@@ -0,0 +1,547 @@
+# frozen_string_literal: false
+#--
+# = uri/common.rb
+#
+# Author:: Akira Yamada <akira@ruby-lang.org>
+# License::
+#   You can redistribute it and/or modify it under the same term as Ruby.
+#
+# See Bundler::URI for general documentation
+#
+
+module Bundler::URI
+  #
+  # Includes Bundler::URI::REGEXP::PATTERN
+  #
+  module RFC2396_REGEXP
+    #
+    # Patterns used to parse Bundler::URI's
+    #
+    module PATTERN
+      # :stopdoc:
+
+      # RFC 2396 (Bundler::URI Generic Syntax)
+      # RFC 2732 (IPv6 Literal Addresses in URL's)
+      # RFC 2373 (IPv6 Addressing Architecture)
+
+      # alpha         = lowalpha | upalpha
+      ALPHA = "a-zA-Z"
+      # alphanum      = alpha | digit
+      ALNUM = "#{ALPHA}\\d"
+
+      # hex           = digit | "A" | "B" | "C" | "D" | "E" | "F" |
+      #                         "a" | "b" | "c" | "d" | "e" | "f"
+      HEX     = "a-fA-F\\d"
+      # escaped       = "%" hex hex
+      ESCAPED = "%[#{HEX}]{2}"
+      # mark          = "-" | "_" | "." | "!" | "~" | "*" | "'" |
+      #                 "(" | ")"
+      # unreserved    = alphanum | mark
+      UNRESERVED = "\\-_.!~*'()#{ALNUM}"
+      # reserved      = ";" | "/" | "?" | ":" | "@" | "&" | "=" | "+" |
+      #                 "$" | ","
+      # reserved      = ";" | "/" | "?" | ":" | "@" | "&" | "=" | "+" |
+      #                 "$" | "," | "[" | "]" (RFC 2732)
+      RESERVED = ";/?:@&=+$,\\[\\]"
+
+      # domainlabel   = alphanum | alphanum *( alphanum | "-" ) alphanum
+      DOMLABEL = "(?:[#{ALNUM}](?:[-#{ALNUM}]*[#{ALNUM}])?)"
+      # toplabel      = alpha | alpha *( alphanum | "-" ) alphanum
+      TOPLABEL = "(?:[#{ALPHA}](?:[-#{ALNUM}]*[#{ALNUM}])?)"
+      # hostname      = *( domainlabel "." ) toplabel [ "." ]
+      HOSTNAME = "(?:#{DOMLABEL}\\.)*#{TOPLABEL}\\.?"
+
+      # :startdoc:
+    end # PATTERN
+
+    # :startdoc:
+  end # REGEXP
+
+  # Class that parses String's into Bundler::URI's.
+  #
+  # It contains a Hash set of patterns and Regexp's that match and validate.
+  #
+  class RFC2396_Parser
+    include RFC2396_REGEXP
+
+    #
+    # == Synopsis
+    #
+    #   Bundler::URI::RFC2396_Parser.new([opts])
+    #
+    # == Args
+    #
+    # The constructor accepts a hash as options for parser.
+    # Keys of options are pattern names of Bundler::URI components
+    # and values of options are pattern strings.
+    # The constructor generates set of regexps for parsing URIs.
+    #
+    # You can use the following keys:
+    #
+    #   * :ESCAPED (Bundler::URI::PATTERN::ESCAPED in default)
+    #   * :UNRESERVED (Bundler::URI::PATTERN::UNRESERVED in default)
+    #   * :DOMLABEL (Bundler::URI::PATTERN::DOMLABEL in default)
+    #   * :TOPLABEL (Bundler::URI::PATTERN::TOPLABEL in default)
+    #   * :HOSTNAME (Bundler::URI::PATTERN::HOSTNAME in default)
+    #
+    # == Examples
+    #
+    #   p = Bundler::URI::RFC2396_Parser.new(:ESCAPED => "(?:%[a-fA-F0-9]{2}|%u[a-fA-F0-9]{4})")
+    #   u = p.parse("http://example.jp/%uABCD") #=> #<Bundler::URI::HTTP http://example.jp/%uABCD>
+    #   Bundler::URI.parse(u.to_s) #=> raises Bundler::URI::InvalidURIError
+    #
+    #   s = "http://example.com/ABCD"
+    #   u1 = p.parse(s) #=> #<Bundler::URI::HTTP http://example.com/ABCD>
+    #   u2 = Bundler::URI.parse(s) #=> #<Bundler::URI::HTTP http://example.com/ABCD>
+    #   u1 == u2 #=> true
+    #   u1.eql?(u2) #=> false
+    #
+    def initialize(opts = {})
+      @pattern = initialize_pattern(opts)
+      @pattern.each_value(&:freeze)
+      @pattern.freeze
+
+      @regexp = initialize_regexp(@pattern)
+      @regexp.each_value(&:freeze)
+      @regexp.freeze
+    end
+
+    # The Hash of patterns.
+    #
+    # See also #initialize_pattern.
+    attr_reader :pattern
+
+    # The Hash of Regexp.
+    #
+    # See also #initialize_regexp.
+    attr_reader :regexp
+
+    # Returns a split Bundler::URI against +regexp[:ABS_URI]+.
+    def split(uri)
+      case uri
+      when ''
+        # null uri
+
+      when @regexp[:ABS_URI]
+        scheme, opaque, userinfo, host, port,
+          registry, path, query, fragment = $~[1..-1]
+
+        # Bundler::URI-reference = [ absoluteURI | relativeURI ] [ "#" fragment ]
+
+        # absoluteURI   = scheme ":" ( hier_part | opaque_part )
+        # hier_part     = ( net_path | abs_path ) [ "?" query ]
+        # opaque_part   = uric_no_slash *uric
+
+        # abs_path      = "/"  path_segments
+        # net_path      = "//" authority [ abs_path ]
+
+        # authority     = server | reg_name
+        # server        = [ [ userinfo "@" ] hostport ]
+
+        if !scheme
+          raise InvalidURIError,
+            "bad Bundler::URI (absolute but no scheme): #{uri}"
+        end
+        if !opaque && (!path && (!host && !registry))
+          raise InvalidURIError,
+            "bad Bundler::URI (absolute but no path): #{uri}"
+        end
+
+      when @regexp[:REL_URI]
+        scheme = nil
+        opaque = nil
+
+        userinfo, host, port, registry,
+          rel_segment, abs_path, query, fragment = $~[1..-1]
+        if rel_segment && abs_path
+          path = rel_segment + abs_path
+        elsif rel_segment
+          path = rel_segment
+        elsif abs_path
+          path = abs_path
+        end
+
+        # Bundler::URI-reference = [ absoluteURI | relativeURI ] [ "#" fragment ]
+
+        # relativeURI   = ( net_path | abs_path | rel_path ) [ "?" query ]
+
+        # net_path      = "//" authority [ abs_path ]
+        # abs_path      = "/"  path_segments
+        # rel_path      = rel_segment [ abs_path ]
+
+        # authority     = server | reg_name
+        # server        = [ [ userinfo "@" ] hostport ]
+
+      else
+        raise InvalidURIError, "bad Bundler::URI (is not Bundler::URI?): #{uri}"
+      end
+
+      path = '' if !path && !opaque # (see RFC2396 Section 5.2)
+      ret = [
+        scheme,
+        userinfo, host, port,         # X
+        registry,                     # X
+        path,                         # Y
+        opaque,                       # Y
+        query,
+        fragment
+      ]
+      return ret
+    end
+
+    #
+    # == Args
+    #
+    # +uri+::
+    #    String
+    #
+    # == Description
+    #
+    # Parses +uri+ and constructs either matching Bundler::URI scheme object
+    # (File, FTP, HTTP, HTTPS, LDAP, LDAPS, or MailTo) or Bundler::URI::Generic.
+    #
+    # == Usage
+    #
+    #   Bundler::URI::RFC2396_PARSER.parse("ldap://ldap.example.com/dc=example?user=john")
+    #   #=> #<Bundler::URI::LDAP ldap://ldap.example.com/dc=example?user=john>
+    #
+    def parse(uri)
+      Bundler::URI.for(*self.split(uri), self)
+    end
+
+    #
+    # == Args
+    #
+    # +uris+::
+    #    an Array of Strings
+    #
+    # == Description
+    #
+    # Attempts to parse and merge a set of URIs.
+    #
+    def join(*uris)
+      uris[0] = convert_to_uri(uris[0])
+      uris.inject :merge
+    end
+
+    #
+    # :call-seq:
+    #   extract( str )
+    #   extract( str, schemes )
+    #   extract( str, schemes ) {|item| block }
+    #
+    # == Args
+    #
+    # +str+::
+    #    String to search
+    # +schemes+::
+    #    Patterns to apply to +str+
+    #
+    # == Description
+    #
+    # Attempts to parse and merge a set of URIs.
+    # If no +block+ given, then returns the result,
+    # else it calls +block+ for each element in result.
+    #
+    # See also #make_regexp.
+    #
+    def extract(str, schemes = nil)
+      if block_given?
+        str.scan(make_regexp(schemes)) { yield $& }
+        nil
+      else
+        result = []
+        str.scan(make_regexp(schemes)) { result.push $& }
+        result
+      end
+    end
+
+    # Returns Regexp that is default +self.regexp[:ABS_URI_REF]+,
+    # unless +schemes+ is provided. Then it is a Regexp.union with +self.pattern[:X_ABS_URI]+.
+    def make_regexp(schemes = nil)
+      unless schemes
+        @regexp[:ABS_URI_REF]
+      else
+        /(?=(?i:#{Regexp.union(*schemes).source}):)#{@pattern[:X_ABS_URI]}/x
+      end
+    end
+
+    #
+    # :call-seq:
+    #   escape( str )
+    #   escape( str, unsafe )
+    #
+    # == Args
+    #
+    # +str+::
+    #    String to make safe
+    # +unsafe+::
+    #    Regexp to apply. Defaults to +self.regexp[:UNSAFE]+
+    #
+    # == Description
+    #
+    # Constructs a safe String from +str+, removing unsafe characters,
+    # replacing them with codes.
+    #
+    def escape(str, unsafe = @regexp[:UNSAFE])
+      unless unsafe.kind_of?(Regexp)
+        # perhaps unsafe is String object
+        unsafe = Regexp.new("[#{Regexp.quote(unsafe)}]", false)
+      end
+      str.gsub(unsafe) do
+        us = $&
+        tmp = ''
+        us.each_byte do |uc|
+          tmp << sprintf('%%%02X', uc)
+        end
+        tmp
+      end.force_encoding(Encoding::US_ASCII)
+    end
+
+    #
+    # :call-seq:
+    #   unescape( str )
+    #   unescape( str, escaped )
+    #
+    # == Args
+    #
+    # +str+::
+    #    String to remove escapes from
+    # +escaped+::
+    #    Regexp to apply. Defaults to +self.regexp[:ESCAPED]+
+    #
+    # == Description
+    #
+    # Removes escapes from +str+.
+    #
+    def unescape(str, escaped = @regexp[:ESCAPED])
+      enc = str.encoding
+      enc = Encoding::UTF_8 if enc == Encoding::US_ASCII
+      str.gsub(escaped) { [$&[1, 2]].pack('H2').force_encoding(enc) }
+    end
+
+    TO_S = Kernel.instance_method(:to_s) # :nodoc:
+    if TO_S.respond_to?(:bind_call)
+      def inspect # :nodoc:
+        TO_S.bind_call(self)
+      end
+    else
+      def inspect # :nodoc:
+        TO_S.bind(self).call
+      end
+    end
+
+    private
+
+    # Constructs the default Hash of patterns.
+    def initialize_pattern(opts = {})
+      ret = {}
+      ret[:ESCAPED] = escaped = (opts.delete(:ESCAPED) || PATTERN::ESCAPED)
+      ret[:UNRESERVED] = unreserved = opts.delete(:UNRESERVED) || PATTERN::UNRESERVED
+      ret[:RESERVED] = reserved = opts.delete(:RESERVED) || PATTERN::RESERVED
+      ret[:DOMLABEL] = opts.delete(:DOMLABEL) || PATTERN::DOMLABEL
+      ret[:TOPLABEL] = opts.delete(:TOPLABEL) || PATTERN::TOPLABEL
+      ret[:HOSTNAME] = hostname = opts.delete(:HOSTNAME)
+
+      # RFC 2396 (Bundler::URI Generic Syntax)
+      # RFC 2732 (IPv6 Literal Addresses in URL's)
+      # RFC 2373 (IPv6 Addressing Architecture)
+
+      # uric          = reserved | unreserved | escaped
+      ret[:URIC] = uric = "(?:[#{unreserved}#{reserved}]|#{escaped})"
+      # uric_no_slash = unreserved | escaped | ";" | "?" | ":" | "@" |
+      #                 "&" | "=" | "+" | "$" | ","
+      ret[:URIC_NO_SLASH] = uric_no_slash = "(?:[#{unreserved};?:@&=+$,]|#{escaped})"
+      # query         = *uric
+      ret[:QUERY] = query = "#{uric}*"
+      # fragment      = *uric
+      ret[:FRAGMENT] = fragment = "#{uric}*"
+
+      # hostname      = *( domainlabel "." ) toplabel [ "." ]
+      # reg-name      = *( unreserved / pct-encoded / sub-delims ) # RFC3986
+      unless hostname
+        ret[:HOSTNAME] = hostname = "(?:[a-zA-Z0-9\\-.]|%\\h\\h)+"
+      end
+
+      # RFC 2373, APPENDIX B:
+      # IPv6address = hexpart [ ":" IPv4address ]
+      # IPv4address   = 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT
+      # hexpart = hexseq | hexseq "::" [ hexseq ] | "::" [ hexseq ]
+      # hexseq  = hex4 *( ":" hex4)
+      # hex4    = 1*4HEXDIG
+      #
+      # XXX: This definition has a flaw. "::" + IPv4address must be
+      # allowed too.  Here is a replacement.
+      #
+      # IPv4address = 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT
+      ret[:IPV4ADDR] = ipv4addr = "\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}"
+      # hex4     = 1*4HEXDIG
+      hex4 = "[#{PATTERN::HEX}]{1,4}"
+      # lastpart = hex4 | IPv4address
+      lastpart = "(?:#{hex4}|#{ipv4addr})"
+      # hexseq1  = *( hex4 ":" ) hex4
+      hexseq1 = "(?:#{hex4}:)*#{hex4}"
+      # hexseq2  = *( hex4 ":" ) lastpart
+      hexseq2 = "(?:#{hex4}:)*#{lastpart}"
+      # IPv6address = hexseq2 | [ hexseq1 ] "::" [ hexseq2 ]
+      ret[:IPV6ADDR] = ipv6addr = "(?:#{hexseq2}|(?:#{hexseq1})?::(?:#{hexseq2})?)"
+
+      # IPv6prefix  = ( hexseq1 | [ hexseq1 ] "::" [ hexseq1 ] ) "/" 1*2DIGIT
+      # unused
+
+      # ipv6reference = "[" IPv6address "]" (RFC 2732)
+      ret[:IPV6REF] = ipv6ref = "\\[#{ipv6addr}\\]"
+
+      # host          = hostname | IPv4address
+      # host          = hostname | IPv4address | IPv6reference (RFC 2732)
+      ret[:HOST] = host = "(?:#{hostname}|#{ipv4addr}|#{ipv6ref})"
+      # port          = *digit
+      ret[:PORT] = port = '\d*'
+      # hostport      = host [ ":" port ]
+      ret[:HOSTPORT] = hostport = "#{host}(?::#{port})?"
+
+      # userinfo      = *( unreserved | escaped |
+      #                    ";" | ":" | "&" | "=" | "+" | "$" | "," )
+      ret[:USERINFO] = userinfo = "(?:[#{unreserved};:&=+$,]|#{escaped})*"
+
+      # pchar         = unreserved | escaped |
+      #                 ":" | "@" | "&" | "=" | "+" | "$" | ","
+      pchar = "(?:[#{unreserved}:@&=+$,]|#{escaped})"
+      # param         = *pchar
+      param = "#{pchar}*"
+      # segment       = *pchar *( ";" param )
+      segment = "#{pchar}*(?:;#{param})*"
+      # path_segments = segment *( "/" segment )
+      ret[:PATH_SEGMENTS] = path_segments = "#{segment}(?:/#{segment})*"
+
+      # server        = [ [ userinfo "@" ] hostport ]
+      server = "(?:#{userinfo}@)?#{hostport}"
+      # reg_name      = 1*( unreserved | escaped | "$" | "," |
+      #                     ";" | ":" | "@" | "&" | "=" | "+" )
+      ret[:REG_NAME] = reg_name = "(?:[#{unreserved}$,;:@&=+]|#{escaped})+"
+      # authority     = server | reg_name
+      authority = "(?:#{server}|#{reg_name})"
+
+      # rel_segment   = 1*( unreserved | escaped |
+      #                     ";" | "@" | "&" | "=" | "+" | "$" | "," )
+      ret[:REL_SEGMENT] = rel_segment = "(?:[#{unreserved};@&=+$,]|#{escaped})+"
+
+      # scheme        = alpha *( alpha | digit | "+" | "-" | "." )
+      ret[:SCHEME] = scheme = "[#{PATTERN::ALPHA}][\\-+.#{PATTERN::ALPHA}\\d]*"
+
+      # abs_path      = "/"  path_segments
+      ret[:ABS_PATH] = abs_path = "/#{path_segments}"
+      # rel_path      = rel_segment [ abs_path ]
+      ret[:REL_PATH] = rel_path = "#{rel_segment}(?:#{abs_path})?"
+      # net_path      = "//" authority [ abs_path ]
+      ret[:NET_PATH] = net_path = "//#{authority}(?:#{abs_path})?"
+
+      # hier_part     = ( net_path | abs_path ) [ "?" query ]
+      ret[:HIER_PART] = hier_part = "(?:#{net_path}|#{abs_path})(?:\\?(?:#{query}))?"
+      # opaque_part   = uric_no_slash *uric
+      ret[:OPAQUE_PART] = opaque_part = "#{uric_no_slash}#{uric}*"
+
+      # absoluteURI   = scheme ":" ( hier_part | opaque_part )
+      ret[:ABS_URI] = abs_uri = "#{scheme}:(?:#{hier_part}|#{opaque_part})"
+      # relativeURI   = ( net_path | abs_path | rel_path ) [ "?" query ]
+      ret[:REL_URI] = rel_uri = "(?:#{net_path}|#{abs_path}|#{rel_path})(?:\\?#{query})?"
+
+      # Bundler::URI-reference = [ absoluteURI | relativeURI ] [ "#" fragment ]
+      ret[:URI_REF] = "(?:#{abs_uri}|#{rel_uri})?(?:##{fragment})?"
+
+      ret[:X_ABS_URI] = "
+        (#{scheme}):                           (?# 1: scheme)
+        (?:
+           (#{opaque_part})                    (?# 2: opaque)
+        |
+           (?:(?:
+             //(?:
+                 (?:(?:(#{userinfo})@)?        (?# 3: userinfo)
+                   (?:(#{host})(?::(\\d*))?))? (?# 4: host, 5: port)
+               |
+                 (#{reg_name})                 (?# 6: registry)
+               )
+             |
+             (?!//))                           (?# XXX: '//' is the mark for hostport)
+             (#{abs_path})?                    (?# 7: path)
+           )(?:\\?(#{query}))?                 (?# 8: query)
+        )
+        (?:\\#(#{fragment}))?                  (?# 9: fragment)
+      "
+
+      ret[:X_REL_URI] = "
+        (?:
+          (?:
+            //
+            (?:
+              (?:(#{userinfo})@)?       (?# 1: userinfo)
+                (#{host})?(?::(\\d*))?  (?# 2: host, 3: port)
+            |
+              (#{reg_name})             (?# 4: registry)
+            )
+          )
+        |
+          (#{rel_segment})              (?# 5: rel_segment)
+        )?
+        (#{abs_path})?                  (?# 6: abs_path)
+        (?:\\?(#{query}))?              (?# 7: query)
+        (?:\\#(#{fragment}))?           (?# 8: fragment)
+      "
+
+      ret
+    end
+
+    # Constructs the default Hash of Regexp's.
+    def initialize_regexp(pattern)
+      ret = {}
+
+      # for Bundler::URI::split
+      ret[:ABS_URI] = Regexp.new('\A\s*+' + pattern[:X_ABS_URI] + '\s*\z', Regexp::EXTENDED)
+      ret[:REL_URI] = Regexp.new('\A\s*+' + pattern[:X_REL_URI] + '\s*\z', Regexp::EXTENDED)
+
+      # for Bundler::URI::extract
+      ret[:URI_REF]     = Regexp.new(pattern[:URI_REF])
+      ret[:ABS_URI_REF] = Regexp.new(pattern[:X_ABS_URI], Regexp::EXTENDED)
+      ret[:REL_URI_REF] = Regexp.new(pattern[:X_REL_URI], Regexp::EXTENDED)
+
+      # for Bundler::URI::escape/unescape
+      ret[:ESCAPED] = Regexp.new(pattern[:ESCAPED])
+      ret[:UNSAFE]  = Regexp.new("[^#{pattern[:UNRESERVED]}#{pattern[:RESERVED]}]")
+
+      # for Generic#initialize
+      ret[:SCHEME]   = Regexp.new("\\A#{pattern[:SCHEME]}\\z")
+      ret[:USERINFO] = Regexp.new("\\A#{pattern[:USERINFO]}\\z")
+      ret[:HOST]     = Regexp.new("\\A#{pattern[:HOST]}\\z")
+      ret[:PORT]     = Regexp.new("\\A#{pattern[:PORT]}\\z")
+      ret[:OPAQUE]   = Regexp.new("\\A#{pattern[:OPAQUE_PART]}\\z")
+      ret[:REGISTRY] = Regexp.new("\\A#{pattern[:REG_NAME]}\\z")
+      ret[:ABS_PATH] = Regexp.new("\\A#{pattern[:ABS_PATH]}\\z")
+      ret[:REL_PATH] = Regexp.new("\\A#{pattern[:REL_PATH]}\\z")
+      ret[:QUERY]    = Regexp.new("\\A#{pattern[:QUERY]}\\z")
+      ret[:FRAGMENT] = Regexp.new("\\A#{pattern[:FRAGMENT]}\\z")
+
+      ret
+    end
+
+    # Returns +uri+ as-is if it is Bundler::URI, or convert it to Bundler::URI if it is
+    # a String.
+    def convert_to_uri(uri)
+      if uri.is_a?(Bundler::URI::Generic)
+        uri
+      elsif uri = String.try_convert(uri)
+        parse(uri)
+      else
+        raise ArgumentError,
+          "bad argument (expected Bundler::URI object or Bundler::URI string)"
+      end
+    end
+
+  end # class Parser
+
+  # Backward compatibility for Bundler::URI::REGEXP::PATTERN::*
+  RFC2396_Parser.new.pattern.each_pair do |sym, str|
+    unless RFC2396_REGEXP::PATTERN.const_defined?(sym, false)
+      RFC2396_REGEXP::PATTERN.const_set(sym, str)
+    end
+  end
+end # module Bundler::URI
diff --git a/lib/bundler/vendor/uri/lib/uri/rfc3986_parser.rb b/lib/bundler/vendor/uri/lib/uri/rfc3986_parser.rb
new file mode 100644
index 0000000000..d1ff28df23
--- /dev/null
+++ b/lib/bundler/vendor/uri/lib/uri/rfc3986_parser.rb
@@ -0,0 +1,206 @@
+# frozen_string_literal: true
+module Bundler::URI
+  class RFC3986_Parser # :nodoc:
+    # Bundler::URI defined in RFC3986
+    HOST = %r[
+      (?<IP-literal>\[(?:
+          (?<IPv6address>
+            (?:\h{1,4}:){6}
+            (?<ls32>\h{1,4}:\h{1,4}
+            | (?<IPv4address>(?<dec-octet>[1-9]\d|1\d{2}|2[0-4]\d|25[0-5]|\d)
+                \.\g<dec-octet>\.\g<dec-octet>\.\g<dec-octet>)
+            )
+          | ::(?:\h{1,4}:){5}\g<ls32>
+          | \h{1,4}?::(?:\h{1,4}:){4}\g<ls32>
+          | (?:(?:\h{1,4}:)?\h{1,4})?::(?:\h{1,4}:){3}\g<ls32>
+          | (?:(?:\h{1,4}:){,2}\h{1,4})?::(?:\h{1,4}:){2}\g<ls32>
+          | (?:(?:\h{1,4}:){,3}\h{1,4})?::\h{1,4}:\g<ls32>
+          | (?:(?:\h{1,4}:){,4}\h{1,4})?::\g<ls32>
+          | (?:(?:\h{1,4}:){,5}\h{1,4})?::\h{1,4}
+          | (?:(?:\h{1,4}:){,6}\h{1,4})?::
+          )
+        | (?<IPvFuture>v\h++\.[!$&-.0-9:;=A-Z_a-z~]++)
+        )\])
+    | \g<IPv4address>
+    | (?<reg-name>(?:%\h\h|[!$&-.0-9;=A-Z_a-z~])*+)
+    ]x
+
+    USERINFO = /(?:%\h\h|[!$&-.0-9:;=A-Z_a-z~])*+/
+
+    SCHEME = %r[[A-Za-z][+\-.0-9A-Za-z]*+].source
+    SEG = %r[(?:%\h\h|[!$&-.0-9:;=@A-Z_a-z~/])].source
+    SEG_NC = %r[(?:%\h\h|[!$&-.0-9;=@A-Z_a-z~])].source
+    FRAGMENT = %r[(?:%\h\h|[!$&-.0-9:;=@A-Z_a-z~/?])*+].source
+
+    RFC3986_URI = %r[\A
+    (?<seg>#{SEG}){0}
+    (?<Bundler::URI>
+      (?<scheme>#{SCHEME}):
+      (?<hier-part>//
+        (?<authority>
+          (?:(?<userinfo>#{USERINFO.source})@)?
+          (?<host>#{HOST.source.delete(" \n")})
+          (?::(?<port>\d*+))?
+        )
+        (?<path-abempty>(?:/\g<seg>*+)?)
+      | (?<path-absolute>/((?!/)\g<seg>++)?)
+      | (?<path-rootless>(?!/)\g<seg>++)
+      | (?<path-empty>)
+      )
+      (?:\?(?<query>[^\#]*+))?
+      (?:\#(?<fragment>#{FRAGMENT}))?
+    )\z]x
+
+    RFC3986_relative_ref = %r[\A
+    (?<seg>#{SEG}){0}
+    (?<relative-ref>
+      (?<relative-part>//
+        (?<authority>
+          (?:(?<userinfo>#{USERINFO.source})@)?
+          (?<host>#{HOST.source.delete(" \n")}(?<!/))?
+          (?::(?<port>\d*+))?
+        )
+        (?<path-abempty>(?:/\g<seg>*+)?)
+      | (?<path-absolute>/\g<seg>*+)
+      | (?<path-noscheme>#{SEG_NC}++(?:/\g<seg>*+)?)
+      | (?<path-empty>)
+      )
+      (?:\?(?<query>[^#]*+))?
+      (?:\#(?<fragment>#{FRAGMENT}))?
+    )\z]x
+    attr_reader :regexp
+
+    def initialize
+      @regexp = default_regexp.each_value(&:freeze).freeze
+    end
+
+    def split(uri) #:nodoc:
+      begin
+        uri = uri.to_str
+      rescue NoMethodError
+        raise InvalidURIError, "bad Bundler::URI (is not Bundler::URI?): #{uri.inspect}"
+      end
+      uri.ascii_only? or
+        raise InvalidURIError, "Bundler::URI must be ascii only #{uri.dump}"
+      if m = RFC3986_URI.match(uri)
+        query = m["query"]
+        scheme = m["scheme"]
+        opaque = m["path-rootless"]
+        if opaque
+          opaque << "?#{query}" if query
+          [ scheme,
+            nil, # userinfo
+            nil, # host
+            nil, # port
+            nil, # registry
+            nil, # path
+            opaque,
+            nil, # query
+            m["fragment"]
+          ]
+        else # normal
+          [ scheme,
+            m["userinfo"],
+            m["host"],
+            m["port"],
+            nil, # registry
+            (m["path-abempty"] ||
+             m["path-absolute"] ||
+             m["path-empty"]),
+            nil, # opaque
+            query,
+            m["fragment"]
+          ]
+        end
+      elsif m = RFC3986_relative_ref.match(uri)
+        [ nil, # scheme
+          m["userinfo"],
+          m["host"],
+          m["port"],
+          nil, # registry,
+          (m["path-abempty"] ||
+           m["path-absolute"] ||
+           m["path-noscheme"] ||
+           m["path-empty"]),
+          nil, # opaque
+          m["query"],
+          m["fragment"]
+        ]
+      else
+        raise InvalidURIError, "bad Bundler::URI (is not Bundler::URI?): #{uri.inspect}"
+      end
+    end
+
+    def parse(uri) # :nodoc:
+      Bundler::URI.for(*self.split(uri), self)
+    end
+
+    def join(*uris) # :nodoc:
+      uris[0] = convert_to_uri(uris[0])
+      uris.inject :merge
+    end
+
+    # Compatibility for RFC2396 parser
+    def extract(str, schemes = nil, &block) # :nodoc:
+      warn "Bundler::URI::RFC3986_PARSER.extract is obsolete. Use Bundler::URI::RFC2396_PARSER.extract explicitly.", uplevel: 1 if $VERBOSE
+      RFC2396_PARSER.extract(str, schemes, &block)
+    end
+
+    # Compatibility for RFC2396 parser
+    def make_regexp(schemes = nil) # :nodoc:
+      warn "Bundler::URI::RFC3986_PARSER.make_regexp is obsolete. Use Bundler::URI::RFC2396_PARSER.make_regexp explicitly.", uplevel: 1 if $VERBOSE
+      RFC2396_PARSER.make_regexp(schemes)
+    end
+
+    # Compatibility for RFC2396 parser
+    def escape(str, unsafe = nil) # :nodoc:
+      warn "Bundler::URI::RFC3986_PARSER.escape is obsolete. Use Bundler::URI::RFC2396_PARSER.escape explicitly.", uplevel: 1 if $VERBOSE
+      unsafe ? RFC2396_PARSER.escape(str, unsafe) : RFC2396_PARSER.escape(str)
+    end
+
+    # Compatibility for RFC2396 parser
+    def unescape(str, escaped = nil) # :nodoc:
+      warn "Bundler::URI::RFC3986_PARSER.unescape is obsolete. Use Bundler::URI::RFC2396_PARSER.unescape explicitly.", uplevel: 1 if $VERBOSE
+      escaped ? RFC2396_PARSER.unescape(str, escaped) : RFC2396_PARSER.unescape(str)
+    end
+
+    @@to_s = Kernel.instance_method(:to_s)
+    if @@to_s.respond_to?(:bind_call)
+      def inspect
+        @@to_s.bind_call(self)
+      end
+    else
+      def inspect
+        @@to_s.bind(self).call
+      end
+    end
+
+    private
+
+    def default_regexp # :nodoc:
+      {
+        SCHEME: %r[\A#{SCHEME}\z]o,
+        USERINFO: %r[\A#{USERINFO}\z]o,
+        HOST: %r[\A#{HOST}\z]o,
+        ABS_PATH: %r[\A/#{SEG}*+\z]o,
+        REL_PATH: %r[\A(?!/)#{SEG}++\z]o,
+        QUERY: %r[\A(?:%\h\h|[!$&-.0-9:;=@A-Z_a-z~/?])*+\z],
+        FRAGMENT: %r[\A#{FRAGMENT}\z]o,
+        OPAQUE: %r[\A(?:[^/].*)?\z],
+        PORT: /\A[\x09\x0a\x0c\x0d ]*+\d*[\x09\x0a\x0c\x0d ]*\z/,
+      }
+    end
+
+    def convert_to_uri(uri)
+      if uri.is_a?(Bundler::URI::Generic)
+        uri
+      elsif uri = String.try_convert(uri)
+        parse(uri)
+      else
+        raise ArgumentError,
+          "bad argument (expected Bundler::URI object or Bundler::URI string)"
+      end
+    end
+
+  end # class Parser
+end # module Bundler::URI
diff --git a/lib/bundler/vendor/uri/lib/uri/version.rb b/lib/bundler/vendor/uri/lib/uri/version.rb
new file mode 100644
index 0000000000..ad76308e81
--- /dev/null
+++ b/lib/bundler/vendor/uri/lib/uri/version.rb
@@ -0,0 +1,6 @@
+module Bundler::URI
+  # :stopdoc:
+  VERSION = '1.1.1'.freeze
+  VERSION_CODE = VERSION.split('.').map{|s| s.rjust(2, '0')}.join.freeze
+  # :startdoc:
+end
diff --git a/lib/bundler/vendor/uri/lib/uri/ws.rb b/lib/bundler/vendor/uri/lib/uri/ws.rb
new file mode 100644
index 0000000000..10ae6f5834
--- /dev/null
+++ b/lib/bundler/vendor/uri/lib/uri/ws.rb
@@ -0,0 +1,83 @@
+# frozen_string_literal: false
+# = uri/ws.rb
+#
+# Author:: Matt Muller <mamuller@amazon.com>
+# License:: You can redistribute it and/or modify it under the same term as Ruby.
+#
+# See Bundler::URI for general documentation
+#
+
+require_relative 'generic'
+
+module Bundler::URI
+
+  #
+  # The syntax of WS URIs is defined in RFC6455 section 3.
+  #
+  # Note that the Ruby Bundler::URI library allows WS URLs containing usernames and
+  # passwords. This is not legal as per the RFC, but used to be
+  # supported in Internet Explorer 5 and 6, before the MS04-004 security
+  # update. See <URL:http://support.microsoft.com/kb/834489>.
+  #
+  class WS < Generic
+    # A Default port of 80 for Bundler::URI::WS.
+    DEFAULT_PORT = 80
+
+    # An Array of the available components for Bundler::URI::WS.
+    COMPONENT = %i[
+      scheme
+      userinfo host port
+      path
+      query
+    ].freeze
+
+    #
+    # == Description
+    #
+    # Creates a new Bundler::URI::WS object from components, with syntax checking.
+    #
+    # The components accepted are userinfo, host, port, path, and query.
+    #
+    # The components should be provided either as an Array, or as a Hash
+    # with keys formed by preceding the component names with a colon.
+    #
+    # If an Array is used, the components must be passed in the
+    # order <code>[userinfo, host, port, path, query]</code>.
+    #
+    # Example:
+    #
+    #     uri = Bundler::URI::WS.build(host: 'www.example.com', path: '/foo/bar')
+    #
+    #     uri = Bundler::URI::WS.build([nil, "www.example.com", nil, "/path", "query"])
+    #
+    # Currently, if passed userinfo components this method generates
+    # invalid WS URIs as per RFC 1738.
+    #
+    def self.build(args)
+      tmp = Util.make_components_hash(self, args)
+      super(tmp)
+    end
+
+    #
+    # == Description
+    #
+    # Returns the full path for a WS Bundler::URI, as required by Net::HTTP::Get.
+    #
+    # If the Bundler::URI contains a query, the full path is Bundler::URI#path + '?' + Bundler::URI#query.
+    # Otherwise, the path is simply Bundler::URI#path.
+    #
+    # Example:
+    #
+    #     uri = Bundler::URI::WS.build(path: '/foo/bar', query: 'test=true')
+    #     uri.request_uri #  => "/foo/bar?test=true"
+    #
+    def request_uri
+      return unless @path
+
+      url = @query ? "#@path?#@query" : @path.dup
+      url.start_with?(?/.freeze) ? url : ?/ + url
+    end
+  end
+
+  register_scheme 'WS', WS
+end
diff --git a/lib/bundler/vendor/uri/lib/uri/wss.rb b/lib/bundler/vendor/uri/lib/uri/wss.rb
new file mode 100644
index 0000000000..e8db1ceabf
--- /dev/null
+++ b/lib/bundler/vendor/uri/lib/uri/wss.rb
@@ -0,0 +1,23 @@
+# frozen_string_literal: false
+# = uri/wss.rb
+#
+# Author:: Matt Muller <mamuller@amazon.com>
+# License:: You can redistribute it and/or modify it under the same term as Ruby.
+#
+# See Bundler::URI for general documentation
+#
+
+require_relative 'ws'
+
+module Bundler::URI
+
+  # The default port for WSS URIs is 443, and the scheme is 'wss:' rather
+  # than 'ws:'. Other than that, WSS URIs are identical to WS URIs;
+  # see Bundler::URI::WS.
+  class WSS < WS
+    # A Default port of 443 for Bundler::URI::WSS
+    DEFAULT_PORT = 443
+  end
+
+  register_scheme 'WSS', WSS
+end
diff --git a/lib/bundler/vendored_fileutils.rb b/lib/bundler/vendored_fileutils.rb
new file mode 100644
index 0000000000..1be1138ce2
--- /dev/null
+++ b/lib/bundler/vendored_fileutils.rb
@@ -0,0 +1,4 @@
+# frozen_string_literal: true
+
+module Bundler; end
+require_relative "vendor/fileutils/lib/fileutils"
diff --git a/lib/bundler/vendored_net_http.rb b/lib/bundler/vendored_net_http.rb
new file mode 100644
index 0000000000..8ff2ccd1fe
--- /dev/null
+++ b/lib/bundler/vendored_net_http.rb
@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+# This defined? guard can be removed once RubyGems 3.4 support is dropped.
+#
+# Bundler specs load this code from `spec/support/vendored_net_http.rb` to avoid
+# activating the Bundler gem too early. Without this guard, we get redefinition
+# warnings once Bundler is actually activated and
+# `lib/bundler/vendored_net_http.rb` is required. This is not an issue in
+# RubyGems versions including `rubygems/vendored_net_http` since `require` takes
+# care of avoiding the double load.
+#
+unless defined?(Gem::Net)
+  begin
+    require "rubygems/vendored_net_http"
+  rescue LoadError
+    begin
+      require "rubygems/net/http"
+    rescue LoadError
+      require "net/http"
+      Gem::Net = Net
+    end
+  end
+end
diff --git a/lib/bundler/vendored_persistent.rb b/lib/bundler/vendored_persistent.rb
new file mode 100644
index 0000000000..ab985c267f
--- /dev/null
+++ b/lib/bundler/vendored_persistent.rb
@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+module Bundler
+  module Persistent
+    module Net
+      module HTTP
+      end
+    end
+  end
+end
+require_relative "vendor/net-http-persistent/lib/net/http/persistent"
diff --git a/lib/bundler/vendored_pub_grub.rb b/lib/bundler/vendored_pub_grub.rb
new file mode 100644
index 0000000000..b36a996b29
--- /dev/null
+++ b/lib/bundler/vendored_pub_grub.rb
@@ -0,0 +1,4 @@
+# frozen_string_literal: true
+
+module Bundler; end
+require_relative "vendor/pub_grub/lib/pub_grub"
diff --git a/lib/bundler/vendored_securerandom.rb b/lib/bundler/vendored_securerandom.rb
new file mode 100644
index 0000000000..6a704dbd40
--- /dev/null
+++ b/lib/bundler/vendored_securerandom.rb
@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+# Use RubyGems vendored copy when available. Otherwise fallback to Bundler
+# vendored copy. The vendored copy in Bundler can be removed once support for
+# RubyGems 3.5.18 is dropped.
+
+begin
+  require "rubygems/vendored_securerandom"
+rescue LoadError
+  require_relative "vendor/securerandom/lib/securerandom"
+  Gem::SecureRandom = Bundler::SecureRandom
+end
diff --git a/lib/bundler/vendored_thor.rb b/lib/bundler/vendored_thor.rb
new file mode 100644
index 0000000000..0666cfc9b9
--- /dev/null
+++ b/lib/bundler/vendored_thor.rb
@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+module Bundler
+  def self.require_thor_actions
+    require_relative "vendor/thor/lib/thor/actions"
+  end
+end
+require_relative "vendor/thor/lib/thor"
diff --git a/lib/bundler/vendored_timeout.rb b/lib/bundler/vendored_timeout.rb
new file mode 100644
index 0000000000..9b2507c0cc
--- /dev/null
+++ b/lib/bundler/vendored_timeout.rb
@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+begin
+  require "rubygems/vendored_timeout"
+rescue LoadError
+  begin
+    require "rubygems/timeout"
+  rescue LoadError
+    require "timeout"
+    Gem::Timeout = Timeout
+  end
+end
diff --git a/lib/bundler/vendored_tsort.rb b/lib/bundler/vendored_tsort.rb
new file mode 100644
index 0000000000..38aed0b5de
--- /dev/null
+++ b/lib/bundler/vendored_tsort.rb
@@ -0,0 +1,4 @@
+# frozen_string_literal: true
+
+module Bundler; end
+require_relative "vendor/tsort/lib/tsort"
diff --git a/lib/bundler/vendored_uri.rb b/lib/bundler/vendored_uri.rb
new file mode 100644
index 0000000000..2efddc65f9
--- /dev/null
+++ b/lib/bundler/vendored_uri.rb
@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+module Bundler; end
+
+# Use RubyGems vendored copy when available. Otherwise fallback to Bundler
+# vendored copy. The vendored copy in Bundler can be removed once support for
+# RubyGems 3.5 is dropped.
+
+begin
+  require "rubygems/vendor/uri/lib/uri"
+rescue LoadError
+  require_relative "vendor/uri/lib/uri"
+  Gem::URI = Bundler::URI
+
+  module Gem
+    def URI(uri) # rubocop:disable Naming/MethodName
+      Bundler::URI(uri)
+    end
+    module_function :URI
+  end
+end
diff --git a/lib/bundler/version.rb b/lib/bundler/version.rb
new file mode 100644
index 0000000000..ca7bb0719a
--- /dev/null
+++ b/lib/bundler/version.rb
@@ -0,0 +1,21 @@
+# frozen_string_literal: false
+
+module Bundler
+  VERSION = "4.1.0.dev".freeze
+
+  def self.bundler_major_version
+    @bundler_major_version ||= gem_version.segments.first
+  end
+
+  def self.gem_version
+    @gem_version ||= Gem::Version.create(VERSION)
+  end
+
+  def self.verbose_version
+    @verbose_version ||= "#{VERSION}#{simulated_version ? " (simulating Bundler #{simulated_version})" : ""}"
+  end
+
+  def self.simulated_version
+    @simulated_version ||= Bundler.settings[:simulate_version]
+  end
+end
diff --git a/lib/bundler/vlad.rb b/lib/bundler/vlad.rb
new file mode 100644
index 0000000000..c3a3d949a6
--- /dev/null
+++ b/lib/bundler/vlad.rb
@@ -0,0 +1,4 @@
+# frozen_string_literal: true
+
+require_relative "shared_helpers"
+Bundler::SharedHelpers.feature_removed! "The Bundler task for Vlad"
diff --git a/lib/bundler/worker.rb b/lib/bundler/worker.rb
new file mode 100644
index 0000000000..77f4f004aa
--- /dev/null
+++ b/lib/bundler/worker.rb
@@ -0,0 +1,125 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Worker
+    POISON = Object.new
+
+    class WrappedException < StandardError
+      attr_reader :exception
+      def initialize(exn)
+        @exception = exn
+      end
+    end
+
+    # @return [String] the name of the worker
+    attr_reader :name
+
+    # Creates a worker pool of specified size
+    #
+    # @param size [Integer] Size of pool
+    # @param name [String] name the name of the worker
+    # @param func [Proc] job to run in inside the worker pool
+    def initialize(size, name, func)
+      @name = name
+      @request_queue = Thread::Queue.new
+      @request_queue_with_priority = Thread::Queue.new
+      @response_queue = Thread::Queue.new
+      @func = func
+      @size = size
+      @threads = nil
+      @previous_interrupt_handler = nil
+    end
+
+    # Enqueue a request to be executed in the worker pool
+    #
+    # @param obj [String] mostly it is name of spec that should be downloaded
+    def enq(obj, priority: false)
+      queue = priority ? @request_queue_with_priority : @request_queue
+      create_threads unless @threads
+      queue.enq obj
+    end
+
+    # Retrieves results of job function being executed in worker pool
+    def deq
+      result = @response_queue.deq
+      raise result.exception if result.is_a?(WrappedException)
+      result
+    end
+
+    def stop
+      stop_threads
+    end
+
+    private
+
+    def process_queue(i)
+      loop do
+        obj = begin
+          @request_queue_with_priority.deq(true)
+        rescue ThreadError
+          @request_queue.deq(false, timeout: 0.05)
+        end
+
+        next if obj.nil?
+        break if obj.equal? POISON
+        @response_queue.enq apply_func(obj, i)
+      end
+    end
+
+    def apply_func(obj, i)
+      @func.call(obj, i)
+    rescue Exception => e # rubocop:disable Lint/RescueException
+      WrappedException.new(e)
+    end
+
+    # Stop the worker threads by sending a poison object down the request queue
+    # so as worker threads after retrieving it, shut themselves down
+    def stop_threads
+      return unless @threads
+
+      @threads.each { @request_queue.enq POISON }
+      @threads.each(&:join)
+
+      remove_interrupt_handler
+
+      @threads = nil
+    end
+
+    def abort_threads
+      Bundler.ui.debug("\n#{caller.join("\n")}")
+      @threads.each(&:exit)
+      exit 1
+    end
+
+    def create_threads
+      creation_errors = []
+
+      @threads = Array.new(@size) do |i|
+        Thread.start { process_queue(i) }.tap do |thread|
+          thread.name = "#{name} Worker ##{i}"
+        end
+      rescue ThreadError => e
+        creation_errors << e
+        nil
+      end.compact
+
+      add_interrupt_handler unless @threads.empty?
+
+      return if creation_errors.empty?
+
+      message = "Failed to create threads for the #{name} worker: #{creation_errors.map(&:to_s).uniq.join(", ")}"
+      raise ThreadCreationError, message if @threads.empty?
+      Bundler.ui.info message
+    end
+
+    def add_interrupt_handler
+      @previous_interrupt_handler = trap("INT") { abort_threads }
+    end
+
+    def remove_interrupt_handler
+      return unless @previous_interrupt_handler
+
+      trap "INT", @previous_interrupt_handler
+    end
+  end
+end
diff --git a/lib/bundler/yaml_serializer.rb b/lib/bundler/yaml_serializer.rb
new file mode 100644
index 0000000000..ab1eb6dbcf
--- /dev/null
+++ b/lib/bundler/yaml_serializer.rb
@@ -0,0 +1,98 @@
+# frozen_string_literal: true
+
+module Bundler
+  # A stub yaml serializer that can handle only hashes and strings (as of now).
+  module YAMLSerializer
+    module_function
+
+    def dump(hash)
+      yaml = String.new("---")
+      yaml << dump_hash(hash)
+    end
+
+    def dump_hash(hash)
+      yaml = String.new("\n")
+      hash.each do |k, v|
+        yaml << k << ":"
+        if v.is_a?(Hash)
+          yaml << dump_hash(v).gsub(/^(?!$)/, "  ") # indent all non-empty lines
+        elsif v.is_a?(Array) # Expected to be array of strings
+          if v.empty?
+            yaml << " []\n"
+          else
+            yaml << "\n- " << v.map {|s| s.to_s.gsub(/\s+/, " ").inspect }.join("\n- ") << "\n"
+          end
+        else
+          yaml << " " << v.to_s.gsub(/\s+/, " ").inspect << "\n"
+        end
+      end
+      yaml
+    end
+
+    ARRAY_REGEX = /
+      ^
+      (?:[ ]*-[ ]) # '- ' before array items
+      (['"]?) # optional opening quote
+      (.*) # value
+      \1 # matching closing quote
+      $
+    /xo
+
+    HASH_REGEX = /
+      ^
+      ([ ]*) # indentations
+      ([^#]+) # key excludes comment char '#'
+      (?::(?=(?:\s|$))) # :  (without the lookahead the #key includes this when : is present in value)
+      [ ]?
+      (['"]?) # optional opening quote
+      (.*) # value
+      \3 # matching closing quote
+      $
+    /xo
+
+    def load(str)
+      res = {}
+      stack = [res]
+      last_hash = nil
+      last_empty_key = nil
+      str.split(/\r?\n/) do |line|
+        if match = HASH_REGEX.match(line)
+          indent, key, quote, val = match.captures
+          val = strip_comment(val)
+
+          depth = indent.size / 2
+          if quote.empty? && val.empty?
+            new_hash = {}
+            stack[depth][key] = new_hash
+            stack[depth + 1] = new_hash
+            last_empty_key = key
+            last_hash = stack[depth]
+          else
+            val = [] if val == "[]" # empty array
+            stack[depth][key] = val
+          end
+        elsif match = ARRAY_REGEX.match(line)
+          _, val = match.captures
+          val = strip_comment(val)
+
+          last_hash[last_empty_key] = [] unless last_hash[last_empty_key].is_a?(Array)
+
+          last_hash[last_empty_key].push(val)
+        end
+      end
+      res
+    end
+
+    def strip_comment(val)
+      if val.include?("#") && !val.start_with?("#")
+        val.split("#", 2).first.strip
+      else
+        val
+      end
+    end
+
+    class << self
+      private :dump_hash
+    end
+  end
+end
diff --git a/lib/cgi.rb b/lib/cgi.rb
index 31730bd60c..0c403bd19c 100644
--- a/lib/cgi.rb
+++ b/lib/cgi.rb
@@ -1,273 +1,9 @@
-#
-# cgi.rb - cgi support library
-#
-# Copyright (C) 2000  Network Applied Communication Laboratory, Inc.
-#
-# Copyright (C) 2000  Information-technology Promotion Agency, Japan
-#
-# Author: Wakou Aoyama <wakou@ruby-lang.org>
-#
-# Documentation: Wakou Aoyama (RDoc'd and embellished by William Webber)
-#
+# frozen_string_literal: true
 
-raise "Please, use ruby 1.9.0 or later." if RUBY_VERSION < "1.9.0"
+require "cgi/escape"
+warn <<-WARNING, uplevel: Gem::BUNDLED_GEMS.uplevel if $VERBOSE
+CGI library is removed from Ruby 4.0. Please use cgi/escape instead for CGI.escape and CGI.unescape features.
 
-# == Overview
-#
-# The Common Gateway Interface (CGI) is a simple protocol for passing an HTTP
-# request from a web server to a standalone program, and returning the output
-# to the web browser.  Basically, a CGI program is called with the parameters
-# of the request passed in either in the environment (GET) or via $stdin
-# (POST), and everything it prints to $stdout is returned to the client.
-#
-# This file holds the CGI class.  This class provides functionality for
-# retrieving HTTP request parameters, managing cookies, and generating HTML
-# output.
-#
-# The file CGI::Session provides session management functionality; see that
-# class for more details.
-#
-# See http://www.w3.org/CGI/ for more information on the CGI protocol.
-#
-# == Introduction
-#
-# CGI is a large class, providing several categories of methods, many of which
-# are mixed in from other modules.  Some of the documentation is in this class,
-# some in the modules CGI::QueryExtension and CGI::HtmlExtension.  See
-# CGI::Cookie for specific information on handling cookies, and cgi/session.rb
-# (CGI::Session) for information on sessions.
-#
-# For queries, CGI provides methods to get at environmental variables,
-# parameters, cookies, and multipart request data.  For responses, CGI provides
-# methods for writing output and generating HTML.
-#
-# Read on for more details.  Examples are provided at the bottom.
-#
-# == Queries
-#
-# The CGI class dynamically mixes in parameter and cookie-parsing
-# functionality,  environmental variable access, and support for
-# parsing multipart requests (including uploaded files) from the
-# CGI::QueryExtension module.
-#
-# === Environmental Variables
-#
-# The standard CGI environmental variables are available as read-only
-# attributes of a CGI object.  The following is a list of these variables:
-#
-#
-#   AUTH_TYPE               HTTP_HOST          REMOTE_IDENT
-#   CONTENT_LENGTH          HTTP_NEGOTIATE     REMOTE_USER
-#   CONTENT_TYPE            HTTP_PRAGMA        REQUEST_METHOD
-#   GATEWAY_INTERFACE       HTTP_REFERER       SCRIPT_NAME
-#   HTTP_ACCEPT             HTTP_USER_AGENT    SERVER_NAME
-#   HTTP_ACCEPT_CHARSET     PATH_INFO          SERVER_PORT
-#   HTTP_ACCEPT_ENCODING    PATH_TRANSLATED    SERVER_PROTOCOL
-#   HTTP_ACCEPT_LANGUAGE    QUERY_STRING       SERVER_SOFTWARE
-#   HTTP_CACHE_CONTROL      REMOTE_ADDR
-#   HTTP_FROM               REMOTE_HOST
-#
-#
-# For each of these variables, there is a corresponding attribute with the
-# same name, except all lower case and without a preceding HTTP_.
-# +content_length+ and +server_port+ are integers; the rest are strings.
-#
-# === Parameters
-#
-# The method #params() returns a hash of all parameters in the request as
-# name/value-list pairs, where the value-list is an Array of one or more
-# values.  The CGI object itself also behaves as a hash of parameter names
-# to values, but only returns a single value (as a String) for each
-# parameter name.
-#
-# For instance, suppose the request contains the parameter
-# "favourite_colours" with the multiple values "blue" and "green".  The
-# following behaviour would occur:
-#
-#   cgi.params["favourite_colours"]  # => ["blue", "green"]
-#   cgi["favourite_colours"]         # => "blue"
-#
-# If a parameter does not exist, the former method will return an empty
-# array, the latter an empty string.  The simplest way to test for existence
-# of a parameter is by the #has_key? method.
-#
-# === Cookies
-#
-# HTTP Cookies are automatically parsed from the request.  They are available
-# from the #cookies() accessor, which returns a hash from cookie name to
-# CGI::Cookie object.
-#
-# === Multipart requests
-#
-# If a request's method is POST and its content type is multipart/form-data,
-# then it may contain uploaded files.  These are stored by the QueryExtension
-# module in the parameters of the request.  The parameter name is the name
-# attribute of the file input field, as usual.  However, the value is not
-# a string, but an IO object, either an IOString for small files, or a
-# Tempfile for larger ones.  This object also has the additional singleton
-# methods:
-#
-# #local_path():: the path of the uploaded file on the local filesystem
-# #original_filename():: the name of the file on the client computer
-# #content_type():: the content type of the file
-#
-# == Responses
-#
-# The CGI class provides methods for sending header and content output to
-# the HTTP client, and mixes in methods for programmatic HTML generation
-# from CGI::HtmlExtension and CGI::TagMaker modules.  The precise version of HTML
-# to use for HTML generation is specified at object creation time.
-#
-# === Writing output
-#
-# The simplest way to send output to the HTTP client is using the #out() method.
-# This takes the HTTP headers as a hash parameter, and the body content
-# via a block.  The headers can be generated as a string using the #header()
-# method.  The output stream can be written directly to using the #print()
-# method.
-#
-# === Generating HTML
-#
-# Each HTML element has a corresponding method for generating that
-# element as a String.  The name of this method is the same as that
-# of the element, all lowercase.  The attributes of the element are
-# passed in as a hash, and the body as a no-argument block that evaluates
-# to a String.  The HTML generation module knows which elements are
-# always empty, and silently drops any passed-in body.  It also knows
-# which elements require matching closing tags and which don't.  However,
-# it does not know what attributes are legal for which elements.
-#
-# There are also some additional HTML generation methods mixed in from
-# the CGI::HtmlExtension module.  These include individual methods for the
-# different types of form inputs, and methods for elements that commonly
-# take particular attributes where the attributes can be directly specified
-# as arguments, rather than via a hash.
-#
-# == Examples of use
-#
-# === Get form values
-#
-#   require "cgi"
-#   cgi = CGI.new
-#   value = cgi['field_name']   # <== value string for 'field_name'
-#     # if not 'field_name' included, then return "".
-#   fields = cgi.keys            # <== array of field names
-#
-#   # returns true if form has 'field_name'
-#   cgi.has_key?('field_name')
-#   cgi.has_key?('field_name')
-#   cgi.include?('field_name')
-#
-# CAUTION! cgi['field_name'] returned an Array with the old
-# cgi.rb(included in ruby 1.6)
-#
-# === Get form values as hash
-#
-#   require "cgi"
-#   cgi = CGI.new
-#   params = cgi.params
-#
-# cgi.params is a hash.
-#
-#   cgi.params['new_field_name'] = ["value"]  # add new param
-#   cgi.params['field_name'] = ["new_value"]  # change value
-#   cgi.params.delete('field_name')           # delete param
-#   cgi.params.clear                          # delete all params
-#
-#
-# === Save form values to file
-#
-#   require "pstore"
-#   db = PStore.new("query.db")
-#   db.transaction do
-#     db["params"] = cgi.params
-#   end
-#
-#
-# === Restore form values from file
-#
-#   require "pstore"
-#   db = PStore.new("query.db")
-#   db.transaction do
-#     cgi.params = db["params"]
-#   end
-#
-#
-# === Get multipart form values
-#
-#   require "cgi"
-#   cgi = CGI.new
-#   value = cgi['field_name']   # <== value string for 'field_name'
-#   value.read                  # <== body of value
-#   value.local_path            # <== path to local file of value
-#   value.original_filename     # <== original filename of value
-#   value.content_type          # <== content_type of value
-#
-# and value has StringIO or Tempfile class methods.
-#
-# === Get cookie values
-#
-#   require "cgi"
-#   cgi = CGI.new
-#   values = cgi.cookies['name']  # <== array of 'name'
-#     # if not 'name' included, then return [].
-#   names = cgi.cookies.keys      # <== array of cookie names
-#
-# and cgi.cookies is a hash.
-#
-# === Get cookie objects
-#
-#   require "cgi"
-#   cgi = CGI.new
-#   for name, cookie in cgi.cookies
-#     cookie.expires = Time.now + 30
-#   end
-#   cgi.out("cookie" => cgi.cookies) {"string"}
-#
-#   cgi.cookies # { "name1" => cookie1, "name2" => cookie2, ... }
-#
-#   require "cgi"
-#   cgi = CGI.new
-#   cgi.cookies['name'].expires = Time.now + 30
-#   cgi.out("cookie" => cgi.cookies['name']) {"string"}
-#
-# === Print http header and html string to $DEFAULT_OUTPUT ($>)
-#
-#   require "cgi"
-#   cgi = CGI.new("html3")  # add HTML generation methods
-#   cgi.out() do
-#     cgi.html() do
-#       cgi.head{ cgi.title{"TITLE"} } +
-#       cgi.body() do
-#         cgi.form() do
-#           cgi.textarea("get_text") +
-#           cgi.br +
-#           cgi.submit
-#         end +
-#         cgi.pre() do
-#           CGI::escapeHTML(
-#             "params: " + cgi.params.inspect + "\n" +
-#             "cookies: " + cgi.cookies.inspect + "\n" +
-#             ENV.collect() do |key, value|
-#               key + " --> " + value + "\n"
-#             end.join("")
-#           )
-#         end
-#       end
-#     end
-#   end
-#
-#   # add HTML generation methods
-#   CGI.new("html3")    # html3.2
-#   CGI.new("html4")    # html4.01 (Strict)
-#   CGI.new("html4Tr")  # html4.01 Transitional
-#   CGI.new("html4Fr")  # html4.01 Frameset
-#
-
-class CGI
-end
-
-require 'cgi/core'
-require 'cgi/cookie'
-require 'cgi/util'
-CGI.autoload(:HtmlExtension, 'cgi/html')
+If you need to use the full features of CGI library, please add 'gem "cgi"' to your script
+or use Bundler to ensure you are using the cgi gem instead of this file.
+WARNING
diff --git a/lib/cgi/cookie.rb b/lib/cgi/cookie.rb
deleted file mode 100644
index c2526931d5..0000000000
--- a/lib/cgi/cookie.rb
+++ /dev/null
@@ -1,164 +0,0 @@
-class CGI
-  @@accept_charset="UTF-8" unless defined?(@@accept_charset)
-  # Class representing an HTTP cookie.
-  #
-  # In addition to its specific fields and methods, a Cookie instance
-  # is a delegator to the array of its values.
-  #
-  # See RFC 2965.
-  #
-  # == Examples of use
-  #   cookie1 = CGI::Cookie::new("name", "value1", "value2", ...)
-  #   cookie1 = CGI::Cookie::new("name" => "name", "value" => "value")
-  #   cookie1 = CGI::Cookie::new('name'    => 'name',
-  #                              'value'   => ['value1', 'value2', ...],
-  #                              'path'    => 'path',   # optional
-  #                              'domain'  => 'domain', # optional
-  #                              'expires' => Time.now, # optional
-  #                              'secure'  => true      # optional
-  #                             )
-  #
-  #   cgi.out("cookie" => [cookie1, cookie2]) { "string" }
-  #
-  #   name    = cookie1.name
-  #   values  = cookie1.value
-  #   path    = cookie1.path
-  #   domain  = cookie1.domain
-  #   expires = cookie1.expires
-  #   secure  = cookie1.secure
-  #
-  #   cookie1.name    = 'name'
-  #   cookie1.value   = ['value1', 'value2', ...]
-  #   cookie1.path    = 'path'
-  #   cookie1.domain  = 'domain'
-  #   cookie1.expires = Time.now + 30
-  #   cookie1.secure  = true
-  class Cookie < Array
-
-    # Create a new CGI::Cookie object.
-    #
-    # :call-seq:
-    #   Cookie.new(name_string,*value)
-    #   Cookie.new(options_hash)
-    #
-    # +name_string+::
-    #   The name of the cookie; in this form, there is no #domain or
-    #   #expiration.  The #path is gleaned from the +SCRIPT_NAME+ environment
-    #   variable, and #secure is false.
-    # <tt>*value</tt>::
-    #   value or list of values of the cookie
-    # +options_hash+::
-    #   A Hash of options to initialize this Cookie.  Possible options are:
-    #
-    #   name:: the name of the cookie.  Required.
-    #   value:: the cookie's value or list of values.
-    #   path:: the path for which this cookie applies.  Defaults to the
-    #          the value of the +SCRIPT_NAME+ environment variable.
-    #   domain:: the domain for which this cookie applies.
-    #   expires:: the time at which this cookie expires, as a +Time+ object.
-    #   secure:: whether this cookie is a secure cookie or not (default to
-    #            false).  Secure cookies are only transmitted to HTTPS
-    #            servers.
-    #
-    #   These keywords correspond to attributes of the cookie object.
-    def initialize(name = "", *value)
-      @domain = nil
-      @expires = nil
-      if name.kind_of?(String)
-        @name = name
-        %r|^(.*/)|.match(ENV["SCRIPT_NAME"])
-        @path = ($1 or "")
-        @secure = false
-        return super(value)
-      end
-
-      options = name
-      unless options.has_key?("name")
-        raise ArgumentError, "`name' required"
-      end
-
-      @name = options["name"]
-      value = Array(options["value"])
-      # simple support for IE
-      if options["path"]
-        @path = options["path"]
-      else
-        %r|^(.*/)|.match(ENV["SCRIPT_NAME"])
-        @path = ($1 or "")
-      end
-      @domain = options["domain"]
-      @expires = options["expires"]
-      @secure = options["secure"] == true ? true : false
-
-      super(value)
-    end
-
-    # Name of this cookie, as a +String+
-    attr_accessor :name
-    # Path for which this cookie applies, as a +String+
-    attr_accessor :path
-    # Domain for which this cookie applies, as a +String+
-    attr_accessor :domain
-    # Time at which this cookie expires, as a +Time+
-    attr_accessor :expires
-    # True if this cookie is secure; false otherwise
-    attr_reader("secure")
-
-    # Returns the value or list of values for this cookie.
-    def value
-      self
-    end
-
-    # Replaces the value of this cookie with a new value or list of values.
-    def value=(val)
-      replace(Array(val))
-    end
-
-    # Set whether the Cookie is a secure cookie or not.
-    #
-    # +val+ must be a boolean.
-    def secure=(val)
-      @secure = val if val == true or val == false
-      @secure
-    end
-
-    # Convert the Cookie to its string representation.
-    def to_s
-      val = collect{|v| CGI::escape(v) }.join("&")
-      buf = "#{@name}=#{val}"
-      buf << "; domain=#{@domain}" if @domain
-      buf << "; path=#{@path}"     if @path
-      buf << "; expires=#{CGI::rfc1123_date(@expires)}" if @expires
-      buf << "; secure"            if @secure == true
-      buf
-    end
-
-  end # class Cookie
-
-  # Parse a raw cookie string into a hash of cookie-name=>Cookie
-  # pairs.
-  #
-  #   cookies = CGI::Cookie::parse("raw_cookie_string")
-  #     # { "name1" => cookie1, "name2" => cookie2, ... }
-  #
-  def Cookie::parse(raw_cookie)
-    cookies = Hash.new([])
-    return cookies unless raw_cookie
-
-    raw_cookie.split(/[;,]\s?/).each do |pairs|
-      name, values = pairs.split('=',2)
-      next unless name and values
-      name = CGI::unescape(name)
-      values ||= ""
-      values = values.split('&').collect{|v| CGI::unescape(v,@@accept_charset) }
-      if cookies.has_key?(name)
-        values = cookies[name].value + values
-      end
-      cookies[name] = Cookie::new(name, *values)
-    end
-
-    cookies
-  end
-end
-
-
diff --git a/lib/cgi/core.rb b/lib/cgi/core.rb
deleted file mode 100644
index d7ec8981d7..0000000000
--- a/lib/cgi/core.rb
+++ /dev/null
@@ -1,849 +0,0 @@
-#--
-# Methods for generating HTML, parsing CGI-related parameters, and
-# generating HTTP responses.
-#++
-class CGI
-
-  $CGI_ENV = ENV    # for FCGI support
-
-  # String for carriage return
-  CR  = "\015"
-
-  # String for linefeed
-  LF  = "\012"
-
-  # Standard internet newline sequence
-  EOL = CR + LF
-
-  REVISION = '$Id$' #:nodoc:
-
-  # Whether processing will be required in binary vs text
-  NEEDS_BINMODE = File::BINARY != 0
-
-  # Path separators in different environments.
-  PATH_SEPARATOR = {'UNIX'=>'/', 'WINDOWS'=>'\\', 'MACINTOSH'=>':'}
-
-  # HTTP status codes.
-  HTTP_STATUS = {
-    "OK"                  => "200 OK",
-    "PARTIAL_CONTENT"     => "206 Partial Content",
-    "MULTIPLE_CHOICES"    => "300 Multiple Choices",
-    "MOVED"               => "301 Moved Permanently",
-    "REDIRECT"            => "302 Found",
-    "NOT_MODIFIED"        => "304 Not Modified",
-    "BAD_REQUEST"         => "400 Bad Request",
-    "AUTH_REQUIRED"       => "401 Authorization Required",
-    "FORBIDDEN"           => "403 Forbidden",
-    "NOT_FOUND"           => "404 Not Found",
-    "METHOD_NOT_ALLOWED"  => "405 Method Not Allowed",
-    "NOT_ACCEPTABLE"      => "406 Not Acceptable",
-    "LENGTH_REQUIRED"     => "411 Length Required",
-    "PRECONDITION_FAILED" => "412 Precondition Failed",
-    "SERVER_ERROR"        => "500 Internal Server Error",
-    "NOT_IMPLEMENTED"     => "501 Method Not Implemented",
-    "BAD_GATEWAY"         => "502 Bad Gateway",
-    "VARIANT_ALSO_VARIES" => "506 Variant Also Negotiates"
-  }
-
-  # :startdoc:
-
-  # Synonym for ENV.
-  def env_table
-    ENV
-  end
-
-  # Synonym for $stdin.
-  def stdinput
-    $stdin
-  end
-
-  # Synonym for $stdout.
-  def stdoutput
-    $stdout
-  end
-
-  private :env_table, :stdinput, :stdoutput
-
-  # Create an HTTP header block as a string.
-  #
-  # :call-seq:
-  #   headers(content_type_string="text/html")
-  #   headers(headers_hash)
-  #
-  # Includes the empty line that ends the header block.
-  #
-  # +content_type_string+::
-  #   If this form is used, this string is the <tt>Content-Type</tt>
-  # +headers_hash+::
-  #   A Hash of header values. The following header keys are recognized:
-  #
-  #   type:: The Content-Type header.  Defaults to "text/html"
-  #   charset:: The charset of the body, appended to the Content-Type header.
-  #   nph:: A boolean value.  If true, prepend protocol string and status
-  #         code, and date; and sets default values for "server" and
-  #         "connection" if not explicitly set.
-  #   status::
-  #     The HTTP status code as a String, returned as the Status header.  The
-  #     values are:
-  #
-  #     OK:: 200 OK
-  #     PARTIAL_CONTENT:: 206 Partial Content
-  #     MULTIPLE_CHOICES:: 300 Multiple Choices
-  #     MOVED:: 301 Moved Permanently
-  #     REDIRECT:: 302 Found
-  #     NOT_MODIFIED:: 304 Not Modified
-  #     BAD_REQUEST:: 400 Bad Request
-  #     AUTH_REQUIRED:: 401 Authorization Required
-  #     FORBIDDEN:: 403 Forbidden
-  #     NOT_FOUND:: 404 Not Found
-  #     METHOD_NOT_ALLOWED:: 405 Method Not Allowed
-  #     NOT_ACCEPTABLE:: 406 Not Acceptable
-  #     LENGTH_REQUIRED:: 411 Length Required
-  #     PRECONDITION_FAILED:: 412 Precondition Failed
-  #     SERVER_ERROR:: 500 Internal Server Error
-  #     NOT_IMPLEMENTED:: 501 Method Not Implemented
-  #     BAD_GATEWAY:: 502 Bad Gateway
-  #     VARIANT_ALSO_VARIES:: 506 Variant Also Negotiates
-  #
-  #   server:: The server software, returned as the Server header.
-  #   connection:: The connection type, returned as the Connection header (for
-  #                instance, "close".
-  #   length:: The length of the content that will be sent, returned as the
-  #            Content-Length header.
-  #   language:: The language of the content, returned as the Content-Language
-  #              header.
-  #   expires:: The time on which the current content expires, as a +Time+
-  #             object, returned as the Expires header.
-  #   cookie::
-  #     A cookie or cookies, returned as one or more Set-Cookie headers.  The
-  #     value can be the literal string of the cookie; a CGI::Cookie object;
-  #     an Array of literal cookie strings or Cookie objects; or a hash all of
-  #     whose values are literal cookie strings or Cookie objects.
-  #
-  #     These cookies are in addition to the cookies held in the
-  #     @output_cookies field.
-  #
-  #   Other headers can also be set; they are appended as key: value.
-  #
-  # Examples:
-  #
-  #   header
-  #     # Content-Type: text/html
-  #
-  #   header("text/plain")
-  #     # Content-Type: text/plain
-  #
-  #   header("nph"        => true,
-  #          "status"     => "OK",  # == "200 OK"
-  #            # "status"     => "200 GOOD",
-  #          "server"     => ENV['SERVER_SOFTWARE'],
-  #          "connection" => "close",
-  #          "type"       => "text/html",
-  #          "charset"    => "iso-2022-jp",
-  #            # Content-Type: text/html; charset=iso-2022-jp
-  #          "length"     => 103,
-  #          "language"   => "ja",
-  #          "expires"    => Time.now + 30,
-  #          "cookie"     => [cookie1, cookie2],
-  #          "my_header1" => "my_value"
-  #          "my_header2" => "my_value")
-  #
-  # This method does not perform charset conversion.
-  def header(options='text/html')
-    if options.is_a?(String)
-      content_type = options
-      buf = _header_for_string(content_type)
-    elsif options.is_a?(Hash)
-      if options.size == 1 && options.has_key?('type')
-        content_type = options['type']
-        buf = _header_for_string(content_type)
-      else
-        buf = _header_for_hash(options.dup)
-      end
-    else
-      raise ArgumentError.new("expected String or Hash but got #{options.class}")
-    end
-    if defined?(MOD_RUBY)
-      _header_for_modruby(buf)
-      return ''
-    else
-      buf << EOL    # empty line of separator
-      return buf
-    end
-  end # header()
-
-  def _header_for_string(content_type) #:nodoc:
-    buf = ''
-    if nph?()
-      buf << "#{$CGI_ENV['SERVER_PROTOCOL'] || 'HTTP/1.0'} 200 OK#{EOL}"
-      buf << "Date: #{CGI.rfc1123_date(Time.now)}#{EOL}"
-      buf << "Server: #{$CGI_ENV['SERVER_SOFTWARE']}#{EOL}"
-      buf << "Connection: close#{EOL}"
-    end
-    buf << "Content-Type: #{content_type}#{EOL}"
-    if @output_cookies
-      @output_cookies.each {|cookie| buf << "Set-Cookie: #{cookie}#{EOL}" }
-    end
-    return buf
-  end # _header_for_string
-  private :_header_for_string
-
-  def _header_for_hash(options)  #:nodoc:
-    buf = ''
-    ## add charset to option['type']
-    options['type'] ||= 'text/html'
-    charset = options.delete('charset')
-    options['type'] += "; charset=#{charset}" if charset
-    ## NPH
-    options.delete('nph') if defined?(MOD_RUBY)
-    if options.delete('nph') || nph?()
-      protocol = $CGI_ENV['SERVER_PROTOCOL'] || 'HTTP/1.0'
-      status = options.delete('status')
-      status = HTTP_STATUS[status] || status || '200 OK'
-      buf << "#{protocol} #{status}#{EOL}"
-      buf << "Date: #{CGI.rfc1123_date(Time.now)}#{EOL}"
-      options['server'] ||= $CGI_ENV['SERVER_SOFTWARE'] || ''
-      options['connection'] ||= 'close'
-    end
-    ## common headers
-    status = options.delete('status')
-    buf << "Status: #{HTTP_STATUS[status] || status}#{EOL}" if status
-    server = options.delete('server')
-    buf << "Server: #{server}#{EOL}" if server
-    connection = options.delete('connection')
-    buf << "Connection: #{connection}#{EOL}" if connection
-    type = options.delete('type')
-    buf << "Content-Type: #{type}#{EOL}" #if type
-    length = options.delete('length')
-    buf << "Content-Length: #{length}#{EOL}" if length
-    language = options.delete('language')
-    buf << "Content-Language: #{language}#{EOL}" if language
-    expires = options.delete('expires')
-    buf << "Expires: #{CGI.rfc1123_date(expires)}#{EOL}" if expires
-    ## cookie
-    if cookie = options.delete('cookie')
-      case cookie
-      when String, Cookie
-        buf << "Set-Cookie: #{cookie}#{EOL}"
-      when Array
-        arr = cookie
-        arr.each {|c| buf << "Set-Cookie: #{c}#{EOL}" }
-      when Hash
-        hash = cookie
-        hash.each {|name, c| buf << "Set-Cookie: #{c}#{EOL}" }
-      end
-    end
-    if @output_cookies
-      @output_cookies.each {|c| buf << "Set-Cookie: #{c}#{EOL}" }
-    end
-    ## other headers
-    options.each do |key, value|
-      buf << "#{key}: #{value}#{EOL}"
-    end
-    return buf
-  end # _header_for_hash
-  private :_header_for_hash
-
-  def nph?  #:nodoc:
-    return /IIS\/(\d+)/.match($CGI_ENV['SERVER_SOFTWARE']) && $1.to_i < 5
-  end
-
-  def _header_for_modruby(buf)  #:nodoc:
-    request = Apache::request
-    buf.scan(/([^:]+): (.+)#{EOL}/o) do |name, value|
-      warn sprintf("name:%s value:%s\n", name, value) if $DEBUG
-      case name
-      when 'Set-Cookie'
-        request.headers_out.add(name, value)
-      when /^status$/i
-        request.status_line = value
-        request.status = value.to_i
-      when /^content-type$/i
-        request.content_type = value
-      when /^content-encoding$/i
-        request.content_encoding = value
-      when /^location$/i
-        request.status = 302 if request.status == 200
-        request.headers_out[name] = value
-      else
-        request.headers_out[name] = value
-      end
-    end
-    request.send_http_header
-    return ''
-  end
-  private :_header_for_modruby
-
-  # Print an HTTP header and body to $DEFAULT_OUTPUT ($>)
-  #
-  # :call-seq:
-  #   cgi.out(content_type_string='text/html')
-  #   cgi.out(headers_hash)
-  #
-  # +content_type_string+::
-  #   If a string is passed, it is assumed to be the content type.
-  # +headers_hash+::
-  #   This is a Hash of headers, similar to that used by #header.
-  # +block+::
-  #   A block is required and should evaluate to the body of the response.
-  #
-  # <tt>Content-Length</tt> is automatically calculated from the size of
-  # the String returned by the content block.
-  #
-  # If <tt>ENV['REQUEST_METHOD'] == "HEAD"</tt>, then only the header
-  # is output (the content block is still required, but it is ignored).
-  #
-  # If the charset is "iso-2022-jp" or "euc-jp" or "shift_jis" then the
-  # content is converted to this charset, and the language is set to "ja".
-  #
-  # Example:
-  #
-  #   cgi = CGI.new
-  #   cgi.out{ "string" }
-  #     # Content-Type: text/html
-  #     # Content-Length: 6
-  #     #
-  #     # string
-  #
-  #   cgi.out("text/plain") { "string" }
-  #     # Content-Type: text/plain
-  #     # Content-Length: 6
-  #     #
-  #     # string
-  #
-  #   cgi.out("nph"        => true,
-  #           "status"     => "OK",  # == "200 OK"
-  #           "server"     => ENV['SERVER_SOFTWARE'],
-  #           "connection" => "close",
-  #           "type"       => "text/html",
-  #           "charset"    => "iso-2022-jp",
-  #             # Content-Type: text/html; charset=iso-2022-jp
-  #           "language"   => "ja",
-  #           "expires"    => Time.now + (3600 * 24 * 30),
-  #           "cookie"     => [cookie1, cookie2],
-  #           "my_header1" => "my_value",
-  #           "my_header2" => "my_value") { "string" }
-  #      # HTTP/1.1 200 OK
-  #      # Date: Sun, 15 May 2011 17:35:54 GMT
-  #      # Server: Apache 2.2.0
-  #      # Connection: close
-  #      # Content-Type: text/html; charset=iso-2022-jp
-  #      # Content-Length: 6
-  #      # Content-Language: ja
-  #      # Expires: Tue, 14 Jun 2011 17:35:54 GMT
-  #      # Set-Cookie: foo
-  #      # Set-Cookie: bar
-  #      # my_header1: my_value
-  #      # my_header2: my_value
-  #      #
-  #      # string
-  def out(options = "text/html") # :yield:
-
-    options = { "type" => options } if options.kind_of?(String)
-    content = yield
-    options["length"] = content.bytesize.to_s
-    output = stdoutput
-    output.binmode if defined? output.binmode
-    output.print header(options)
-    output.print content unless "HEAD" == env_table['REQUEST_METHOD']
-  end
-
-
-  # Print an argument or list of arguments to the default output stream
-  #
-  #   cgi = CGI.new
-  #   cgi.print    # default:  cgi.print == $DEFAULT_OUTPUT.print
-  def print(*options)
-    stdoutput.print(*options)
-  end
-
-  # Parse an HTTP query string into a hash of key=>value pairs.
-  #
-  #   params = CGI::parse("query_string")
-  #     # {"name1" => ["value1", "value2", ...],
-  #     #  "name2" => ["value1", "value2", ...], ... }
-  #
-  def CGI::parse(query)
-    params = {}
-    query.split(/[&;]/).each do |pairs|
-      key, value = pairs.split('=',2).collect{|v| CGI::unescape(v) }
-      if key && value
-        params.has_key?(key) ? params[key].push(value) : params[key] = [value]
-      elsif key
-        params[key]=[]
-      end
-    end
-    params.default=[].freeze
-    params
-  end
-
-  # Maximum content length of post data
-  ##MAX_CONTENT_LENGTH  = 2 * 1024 * 1024
-
-  # Maximum content length of multipart data
-  MAX_MULTIPART_LENGTH  = 128 * 1024 * 1024
-
-  # Maximum number of request parameters when multipart
-  MAX_MULTIPART_COUNT = 128
-
-  # Mixin module that provides the following:
-  #
-  # 1. Access to the CGI environment variables as methods.  See
-  #    documentation to the CGI class for a list of these variables.  The
-  #    methods are exposed by removing the leading +HTTP_+ (if it exists) and
-  #    downcasing the name.  For example, +auth_type+ will return the
-  #    environment variable +AUTH_TYPE+, and +accept+ will return the value
-  #    for +HTTP_ACCEPT+.
-  #
-  # 2. Access to cookies, including the cookies attribute.
-  #
-  # 3. Access to parameters, including the params attribute, and overloading
-  #    #[] to perform parameter value lookup by key.
-  #
-  # 4. The initialize_query method, for initializing the above
-  #    mechanisms, handling multipart forms, and allowing the
-  #    class to be used in "offline" mode.
-  #
-  module QueryExtension
-
-    %w[ CONTENT_LENGTH SERVER_PORT ].each do |env|
-      define_method(env.sub(/^HTTP_/, '').downcase) do
-        (val = env_table[env]) && Integer(val)
-      end
-    end
-
-    %w[ AUTH_TYPE CONTENT_TYPE GATEWAY_INTERFACE PATH_INFO
-        PATH_TRANSLATED QUERY_STRING REMOTE_ADDR REMOTE_HOST
-        REMOTE_IDENT REMOTE_USER REQUEST_METHOD SCRIPT_NAME
-        SERVER_NAME SERVER_PROTOCOL SERVER_SOFTWARE
-
-        HTTP_ACCEPT HTTP_ACCEPT_CHARSET HTTP_ACCEPT_ENCODING
-        HTTP_ACCEPT_LANGUAGE HTTP_CACHE_CONTROL HTTP_FROM HTTP_HOST
-        HTTP_NEGOTIATE HTTP_PRAGMA HTTP_REFERER HTTP_USER_AGENT ].each do |env|
-      define_method(env.sub(/^HTTP_/, '').downcase) do
-        env_table[env]
-      end
-    end
-
-    # Get the raw cookies as a string.
-    def raw_cookie
-      env_table["HTTP_COOKIE"]
-    end
-
-    # Get the raw RFC2965 cookies as a string.
-    def raw_cookie2
-      env_table["HTTP_COOKIE2"]
-    end
-
-    # Get the cookies as a hash of cookie-name=>Cookie pairs.
-    attr_accessor :cookies
-
-    # Get the parameters as a hash of name=>values pairs, where
-    # values is an Array.
-    attr_reader :params
-
-    # Get the uploaded files as a hash of name=>values pairs
-    attr_reader :files
-
-    # Set all the parameters.
-    def params=(hash)
-      @params.clear
-      @params.update(hash)
-    end
-
-    ##
-    # Parses multipart form elements according to 
-    #   http://www.w3.org/TR/html401/interact/forms.html#h-17.13.4.2
-    #
-    # Returns a hash of multipart form parameters with bodies of type StringIO or 
-    # Tempfile depending on whether the multipart form element exceeds 10 KB
-    #
-    #   params[name => body]
-    #
-    def read_multipart(boundary, content_length)
-      ## read first boundary
-      stdin = stdinput
-      first_line = "--#{boundary}#{EOL}"
-      content_length -= first_line.bytesize
-      status = stdin.read(first_line.bytesize)
-      raise EOFError.new("no content body")  unless status
-      raise EOFError.new("bad content body") unless first_line == status
-      ## parse and set params
-      params = {}
-      @files = {}
-      boundary_rexp = /--#{Regexp.quote(boundary)}(#{EOL}|--)/
-      boundary_size = "#{EOL}--#{boundary}#{EOL}".bytesize
-      boundary_end  = nil
-      buf = ''
-      bufsize = 10 * 1024
-      max_count = MAX_MULTIPART_COUNT
-      n = 0
-      tempfiles = []
-      while true
-        (n += 1) < max_count or raise StandardError.new("too many parameters.")
-        ## create body (StringIO or Tempfile)
-        body = create_body(bufsize < content_length)
-        tempfiles << body if defined?(Tempfile) && body.kind_of?(Tempfile)
-        class << body
-          if method_defined?(:path)
-            alias local_path path
-          else
-            def local_path
-              nil
-            end
-          end
-          attr_reader :original_filename, :content_type
-        end
-        ## find head and boundary
-        head = nil
-        separator = EOL * 2
-        until head && matched = boundary_rexp.match(buf)
-          if !head && pos = buf.index(separator)
-            len  = pos + EOL.bytesize
-            head = buf[0, len]
-            buf  = buf[(pos+separator.bytesize)..-1]
-          else
-            if head && buf.size > boundary_size
-              len = buf.size - boundary_size
-              body.print(buf[0, len])
-              buf[0, len] = ''
-            end
-            c = stdin.read(bufsize < content_length ? bufsize : content_length)
-            raise EOFError.new("bad content body") if c.nil? || c.empty?
-            buf << c
-            content_length -= c.bytesize
-          end
-        end
-        ## read to end of boundary
-        m = matched
-        len = m.begin(0)
-        s = buf[0, len]
-        if s =~ /(\r?\n)\z/
-          s = buf[0, len - $1.bytesize]
-        end
-        body.print(s)
-        buf = buf[m.end(0)..-1]
-        boundary_end = m[1]
-        content_length = -1 if boundary_end == '--'
-        ## reset file cursor position
-        body.rewind
-        ## original filename
-        /Content-Disposition:.* filename=(?:"(.*?)"|([^;\r\n]*))/i.match(head)
-        filename = $1 || $2 || ''
-        filename = CGI.unescape(filename) if unescape_filename?()
-        body.instance_variable_set('@original_filename', filename.taint)
-        ## content type
-        /Content-Type: (.*)/i.match(head)
-        (content_type = $1 || '').chomp!
-        body.instance_variable_set('@content_type', content_type.taint)
-        ## query parameter name
-        /Content-Disposition:.* name=(?:"(.*?)"|([^;\r\n]*))/i.match(head)
-        name = $1 || $2 || ''
-        if body.original_filename.empty?
-          value=body.read.dup.force_encoding(@accept_charset)
-          (params[name] ||= []) << value
-          unless value.valid_encoding?
-            if @accept_charset_error_block
-              @accept_charset_error_block.call(name,value)
-            else
-              raise InvalidEncoding,"Accept-Charset encoding error"
-            end
-          end
-          class << params[name].last;self;end.class_eval do
-            define_method(:read){self}
-            define_method(:original_filename){""}
-            define_method(:content_type){""}
-          end
-        else
-          (params[name] ||= []) << body
-          @files[name]=body
-        end
-        ## break loop
-        break if content_length == -1
-      end
-      raise EOFError, "bad boundary end of body part" unless boundary_end =~ /--/
-      params.default = []
-      params
-    rescue Exception
-      if tempfiles
-        tempfiles.each {|t|
-          if t.path
-            t.unlink
-          end
-        }
-      end
-      raise
-    end # read_multipart
-    private :read_multipart
-    def create_body(is_large)  #:nodoc:
-      if is_large
-        require 'tempfile'
-        body = Tempfile.new('CGI', encoding: "ascii-8bit")
-      else
-        begin
-          require 'stringio'
-          body = StringIO.new("".force_encoding("ascii-8bit"))
-        rescue LoadError
-          require 'tempfile'
-          body = Tempfile.new('CGI', encoding: "ascii-8bit")
-        end
-      end
-      body.binmode if defined? body.binmode
-      return body
-    end
-    def unescape_filename?  #:nodoc:
-      user_agent = $CGI_ENV['HTTP_USER_AGENT']
-      return /Mac/i.match(user_agent) && /Mozilla/i.match(user_agent) && !/MSIE/i.match(user_agent)
-    end
-
-    # offline mode. read name=value pairs on standard input.
-    def read_from_cmdline
-      require "shellwords"
-
-      string = unless ARGV.empty?
-        ARGV.join(' ')
-      else
-        if STDIN.tty?
-          STDERR.print(
-            %|(offline mode: enter name=value pairs on standard input)\n|
-          )
-        end
-        array = readlines rescue nil
-        if not array.nil?
-            array.join(' ').gsub(/\n/n, '')
-        else
-            ""
-        end
-      end.gsub(/\\=/n, '%3D').gsub(/\\&/n, '%26')
-
-      words = Shellwords.shellwords(string)
-
-      if words.find{|x| /=/n.match(x) }
-        words.join('&')
-      else
-        words.join('+')
-      end
-    end
-    private :read_from_cmdline
-
-    # A wrapper class to use a StringIO object as the body and switch
-    # to a TempFile when the passed threshold is passed.
-    # Initialize the data from the query.
-    #
-    # Handles multipart forms (in particular, forms that involve file uploads).
-    # Reads query parameters in the @params field, and cookies into @cookies.
-    def initialize_query()
-      if ("POST" == env_table['REQUEST_METHOD']) and
-         %r|\Amultipart/form-data.*boundary=\"?([^\";,]+)\"?|.match(env_table['CONTENT_TYPE'])
-        raise StandardError.new("too large multipart data.") if env_table['CONTENT_LENGTH'].to_i > MAX_MULTIPART_LENGTH
-        boundary = $1.dup
-        @multipart = true
-        @params = read_multipart(boundary, Integer(env_table['CONTENT_LENGTH']))
-      else
-        @multipart = false
-        @params = CGI::parse(
-                    case env_table['REQUEST_METHOD']
-                    when "GET", "HEAD"
-                      if defined?(MOD_RUBY)
-                        Apache::request.args or ""
-                      else
-                        env_table['QUERY_STRING'] or ""
-                      end
-                    when "POST"
-                      stdinput.binmode if defined? stdinput.binmode
-                      stdinput.read(Integer(env_table['CONTENT_LENGTH'])) or ''
-                    else
-                      read_from_cmdline
-                    end.dup.force_encoding(@accept_charset)
-                  )
-        unless Encoding.find(@accept_charset) == Encoding::ASCII_8BIT
-          @params.each do |key,values|
-            values.each do |value|
-              unless value.valid_encoding?
-                if @accept_charset_error_block
-                  @accept_charset_error_block.call(key,value)
-                else
-                  raise InvalidEncoding,"Accept-Charset encoding error"
-                end
-              end
-            end
-          end
-        end
-      end
-
-      @cookies = CGI::Cookie::parse((env_table['HTTP_COOKIE'] or env_table['COOKIE']))
-    end
-    private :initialize_query
-
-    # Returns whether the form contained multipart/form-data
-    def multipart?
-      @multipart
-    end
-
-    # Get the value for the parameter with a given key.
-    #
-    # If the parameter has multiple values, only the first will be
-    # retrieved; use #params to get the array of values.
-    def [](key)
-      params = @params[key]
-      return '' unless params
-      value = params[0]
-      if @multipart
-        if value
-          return value
-        elsif defined? StringIO
-          StringIO.new("".force_encoding("ascii-8bit"))
-        else
-          Tempfile.new("CGI",encoding:"ascii-8bit")
-        end
-      else
-        str = if value then value.dup else "" end
-        str
-      end
-    end
-
-    # Return all query parameter names as an array of String.
-    def keys(*args)
-      @params.keys(*args)
-    end
-
-    # Returns true if a given query string parameter exists.
-    def has_key?(*args)
-      @params.has_key?(*args)
-    end
-    alias key? has_key?
-    alias include? has_key?
-
-  end # QueryExtension
-
-  # Exception raised when there is an invalid encoding detected
-  class InvalidEncoding < Exception; end
-
-  # @@accept_charset is default accept character set.
-  # This default value default is "UTF-8"
-  # If you want to change the default accept character set
-  # when create a new CGI instance, set this:
-  #
-  #   CGI.accept_charset = "EUC-JP"
-  #
-  @@accept_charset="UTF-8"
-
-  # Return the accept character set for all new CGI instances.
-  def self.accept_charset
-    @@accept_charset
-  end
-
-  # Set the accept character set for all new CGI instances.
-  def self.accept_charset=(accept_charset)
-    @@accept_charset=accept_charset
-  end
-
-  # Return the accept character set for this CGI instance.
-  attr_reader :accept_charset
-
-  # Create a new CGI instance.
-  #
-  # :call-seq:
-  #   CGI.new(tag_maker) { block }
-  #   CGI.new(options_hash = {}) { block }
-  #
-  #
-  # <tt>tag_maker</tt>::
-  #   This is the same as using the +options_hash+ form with the value <tt>{
-  #   :tag_maker => tag_maker }</tt> Note that it is recommended to use the
-  #   +options_hash+ form, since it also allows you specify the charset you
-  #   will accept.
-  # <tt>options_hash</tt>::
-  #   A Hash that recognizes two options:
-  #
-  #   <tt>:accept_charset</tt>::
-  #     specifies encoding of received query string.  If omitted,
-  #     <tt>@@accept_charset</tt> is used.  If the encoding is not valid, a
-  #     CGI::InvalidEncoding will be raised.
-  #
-  #     Example. Suppose <tt>@@accept_charset</tt> is "UTF-8"
-  #
-  #     when not specified:
-  #
-  #         cgi=CGI.new      # @accept_charset # => "UTF-8"
-  #
-  #     when specified as "EUC-JP":
-  #
-  #         cgi=CGI.new(:accept_charset => "EUC-JP") # => "EUC-JP"
-  #
-  #   <tt>:tag_maker</tt>::
-  #     String that specifies which version of the HTML generation methods to
-  #     use.  If not specified, no HTML generation methods will be loaded.
-  #
-  #     The following values are supported:
-  #
-  #     "html3":: HTML 3.x
-  #     "html4":: HTML 4.0
-  #     "html4Tr":: HTML 4.0 Transitional
-  #     "html4Fr":: HTML 4.0 with Framesets
-  #
-  # <tt>block</tt>::
-  #   If provided, the block is called when an invalid encoding is
-  #   encountered. For example:
-  #
-  #     encoding_errors={}
-  #     cgi=CGI.new(:accept_charset=>"EUC-JP") do |name,value|
-  #       encoding_errors[name] = value
-  #     end
-  #
-  # Finally, if the CGI object is not created in a standard CGI call
-  # environment (that is, it can't locate REQUEST_METHOD in its environment),
-  # then it will run in "offline" mode.  In this mode, it reads its parameters
-  # from the command line or (failing that) from standard input.  Otherwise,
-  # cookies and other parameters are parsed automatically from the standard
-  # CGI locations, which varies according to the REQUEST_METHOD.
-  def initialize(options = {}, &block) # :yields: name, value
-    @accept_charset_error_block=block if block_given?
-    @options={:accept_charset=>@@accept_charset}
-    case options
-    when Hash
-      @options.merge!(options)
-    when String
-      @options[:tag_maker]=options
-    end
-    @accept_charset=@options[:accept_charset]
-    if defined?(MOD_RUBY) && !ENV.key?("GATEWAY_INTERFACE")
-      Apache.request.setup_cgi_env
-    end
-
-    extend QueryExtension
-    @multipart = false
-
-    initialize_query()  # set @params, @cookies
-    @output_cookies = nil
-    @output_hidden = nil
-
-    case @options[:tag_maker]
-    when "html3"
-      require 'cgi/html'
-      extend Html3
-      element_init()
-      extend HtmlExtension
-    when "html4"
-      require 'cgi/html'
-      extend Html4
-      element_init()
-      extend HtmlExtension
-    when "html4Tr"
-      require 'cgi/html'
-      extend Html4Tr
-      element_init()
-      extend HtmlExtension
-    when "html4Fr"
-      require 'cgi/html'
-      extend Html4Tr
-      element_init()
-      extend Html4Fr
-      element_init()
-      extend HtmlExtension
-    end
-  end
-
-end   # class CGI
-
-
diff --git a/lib/cgi/escape.rb b/lib/cgi/escape.rb
new file mode 100644
index 0000000000..555d24a5da
--- /dev/null
+++ b/lib/cgi/escape.rb
@@ -0,0 +1,232 @@
+# frozen_string_literal: true
+
+# Since Ruby 4.0, \CGI is a small holder for various escaping methods, included from CGI::Escape
+#
+#    require 'cgi/escape'
+#
+#    CGI.escape("Ruby programming language")
+#    #=> "Ruby+programming+language"
+#    CGI.escapeURIComponent("Ruby programming language")
+#    #=> "Ruby%20programming%20language"
+#
+# See CGI::Escape module for methods list and their description.
+class CGI
+  module Escape; end
+  include Escape
+  extend Escape
+  module EscapeExt; end # :nodoc:
+end
+
+# Web-related escape/unescape functionality.
+module CGI::Escape
+  @@accept_charset = Encoding::UTF_8 unless defined?(@@accept_charset)
+
+  # URL-encode a string into application/x-www-form-urlencoded.
+  # Space characters (<tt>" "</tt>) are encoded with plus signs (<tt>"+"</tt>)
+  #   url_encoded_string = CGI.escape("'Stop!' said Fred")
+  #      # => "%27Stop%21%27+said+Fred"
+  def escape(string)
+    encoding = string.encoding
+    buffer = string.b
+    buffer.gsub!(/([^ a-zA-Z0-9_.\-~]+)/) do |m|
+      '%' + m.unpack('H2' * m.bytesize).join('%').upcase
+    end
+    buffer.tr!(' ', '+')
+    buffer.force_encoding(encoding)
+  end
+
+  # URL-decode an application/x-www-form-urlencoded string with encoding(optional).
+  #   string = CGI.unescape("%27Stop%21%27+said+Fred")
+  #      # => "'Stop!' said Fred"
+  def unescape(string, encoding = @@accept_charset)
+    str = string.tr('+', ' ')
+    str = str.b
+    str.gsub!(/((?:%[0-9a-fA-F]{2})+)/) do |m|
+      [m.delete('%')].pack('H*')
+    end
+    str.force_encoding(encoding)
+    str.valid_encoding? ? str : str.force_encoding(string.encoding)
+  end
+
+  # URL-encode a string following RFC 3986
+  # Space characters (<tt>" "</tt>) are encoded with (<tt>"%20"</tt>)
+  #   url_encoded_string = CGI.escapeURIComponent("'Stop!' said Fred")
+  #      # => "%27Stop%21%27%20said%20Fred"
+  def escapeURIComponent(string)
+    encoding = string.encoding
+    buffer = string.b
+    buffer.gsub!(/([^a-zA-Z0-9_.\-~]+)/) do |m|
+      '%' + m.unpack('H2' * m.bytesize).join('%').upcase
+    end
+    buffer.force_encoding(encoding)
+  end
+  alias escape_uri_component escapeURIComponent
+
+  # URL-decode a string following RFC 3986 with encoding(optional).
+  #   string = CGI.unescapeURIComponent("%27Stop%21%27+said%20Fred")
+  #      # => "'Stop!'+said Fred"
+  def unescapeURIComponent(string, encoding = @@accept_charset)
+    str = string.b
+    str.gsub!(/((?:%[0-9a-fA-F]{2})+)/) do |m|
+      [m.delete('%')].pack('H*')
+    end
+    str.force_encoding(encoding)
+    str.valid_encoding? ? str : str.force_encoding(string.encoding)
+  end
+
+  alias unescape_uri_component unescapeURIComponent
+
+  # The set of special characters and their escaped values
+  TABLE_FOR_ESCAPE_HTML__ = { # :nodoc:
+    "'" => '&#39;',
+    '&' => '&amp;',
+    '"' => '&quot;',
+    '<' => '&lt;',
+    '>' => '&gt;',
+  }
+
+  # \Escape special characters in HTML, namely <tt>'&\"<></tt>
+  #   CGI.escapeHTML('Usage: foo "bar" <baz>')
+  #      # => "Usage: foo &quot;bar&quot; &lt;baz&gt;"
+  def escapeHTML(string)
+    enc = string.encoding
+    unless enc.ascii_compatible?
+      if enc.dummy?
+        origenc = enc
+        enc = Encoding::Converter.asciicompat_encoding(enc)
+        string = enc ? string.encode(enc) : string.b
+      end
+      table = Hash[TABLE_FOR_ESCAPE_HTML__.map {|pair|pair.map {|s|s.encode(enc)}}]
+      string = string.gsub(/#{"['&\"<>]".encode(enc)}/, table)
+      string.encode!(origenc) if origenc
+      string
+    else
+      string = string.b
+      string.gsub!(/['&\"<>]/, TABLE_FOR_ESCAPE_HTML__)
+      string.force_encoding(enc)
+    end
+  end
+
+  # Unescape a string that has been HTML-escaped
+  #   CGI.unescapeHTML("Usage: foo &quot;bar&quot; &lt;baz&gt;")
+  #      # => "Usage: foo \"bar\" <baz>"
+  def unescapeHTML(string)
+    enc = string.encoding
+    unless enc.ascii_compatible?
+      if enc.dummy?
+        origenc = enc
+        enc = Encoding::Converter.asciicompat_encoding(enc)
+        string = enc ? string.encode(enc) : string.b
+      end
+      string = string.gsub(Regexp.new('&(apos|amp|quot|gt|lt|#[0-9]+|#x[0-9A-Fa-f]+);'.encode(enc))) do
+        case $1.encode(Encoding::US_ASCII)
+        when 'apos'                then "'".encode(enc)
+        when 'amp'                 then '&'.encode(enc)
+        when 'quot'                then '"'.encode(enc)
+        when 'gt'                  then '>'.encode(enc)
+        when 'lt'                  then '<'.encode(enc)
+        when /\A#0*(\d+)\z/        then $1.to_i.chr(enc)
+        when /\A#x([0-9a-f]+)\z/i  then $1.hex.chr(enc)
+        end
+      end
+      string.encode!(origenc) if origenc
+      return string
+    end
+    return string unless string.include? '&'
+    charlimit = case enc
+                when Encoding::UTF_8; 0x10ffff
+                when Encoding::ISO_8859_1; 256
+                else 128
+                end
+    string = string.b
+    string.gsub!(/&(apos|amp|quot|gt|lt|\#[0-9]+|\#[xX][0-9A-Fa-f]+);/) do
+      match = $1.dup
+      case match
+      when 'apos'                then "'"
+      when 'amp'                 then '&'
+      when 'quot'                then '"'
+      when 'gt'                  then '>'
+      when 'lt'                  then '<'
+      when /\A#0*(\d+)\z/
+        n = $1.to_i
+        if n < charlimit
+          n.chr(enc)
+        else
+          "&##{$1};"
+        end
+      when /\A#x([0-9a-f]+)\z/i
+        n = $1.hex
+        if n < charlimit
+          n.chr(enc)
+        else
+          "&#x#{$1};"
+        end
+      else
+        "&#{match};"
+      end
+    end
+    string.force_encoding enc
+  end
+
+  alias escape_html escapeHTML
+  alias h escapeHTML
+
+  alias unescape_html unescapeHTML
+
+  # TruffleRuby runs the pure-Ruby variant faster, do not use the C extension there
+  unless RUBY_ENGINE == 'truffleruby'
+    begin
+      require 'cgi/escape.so'
+    rescue LoadError
+    end
+  end
+
+  # \Escape only the tags of certain HTML elements in +string+.
+  #
+  # Takes an element or elements or array of elements.  Each element
+  # is specified by the name of the element, without angle brackets.
+  # This matches both the start and the end tag of that element.
+  # The attribute list of the open tag will also be escaped (for
+  # instance, the double-quotes surrounding attribute values).
+  #
+  #   print CGI.escapeElement('<BR><A HREF="url"></A>', "A", "IMG")
+  #     # "<BR>&lt;A HREF=&quot;url&quot;&gt;&lt;/A&gt"
+  #
+  #   print CGI.escapeElement('<BR><A HREF="url"></A>', ["A", "IMG"])
+  #     # "<BR>&lt;A HREF=&quot;url&quot;&gt;&lt;/A&gt"
+  def escapeElement(string, *elements)
+    elements = elements[0] if elements[0].kind_of?(Array)
+    unless elements.empty?
+      string.gsub(/<\/?(?:#{elements.join("|")})\b[^<>]*+>?/im) do
+        CGI.escapeHTML($&)
+      end
+    else
+      string
+    end
+  end
+
+  # Undo escaping such as that done by CGI.escapeElement
+  #
+  #   print CGI.unescapeElement(
+  #           CGI.escapeHTML('<BR><A HREF="url"></A>'), "A", "IMG")
+  #     # "&lt;BR&gt;<A HREF="url"></A>"
+  #
+  #   print CGI.unescapeElement(
+  #           CGI.escapeHTML('<BR><A HREF="url"></A>'), ["A", "IMG"])
+  #     # "&lt;BR&gt;<A HREF="url"></A>"
+  def unescapeElement(string, *elements)
+    elements = elements[0] if elements[0].kind_of?(Array)
+    unless elements.empty?
+      string.gsub(/&lt;\/?(?:#{elements.join("|")})\b(?>[^&]+|&(?![gl]t;)\w+;)*(?:&gt;)?/im) do
+        unescapeHTML($&)
+      end
+    else
+      string
+    end
+  end
+
+  alias escape_element escapeElement
+
+  alias unescape_element unescapeElement
+
+end
diff --git a/lib/cgi/html.rb b/lib/cgi/html.rb
deleted file mode 100644
index 04e2431735..0000000000
--- a/lib/cgi/html.rb
+++ /dev/null
@@ -1,1021 +0,0 @@
-class CGI
-  # Base module for HTML-generation mixins.
-  #
-  # Provides methods for code generation for tags following
-  # the various DTD element types.
-  module TagMaker # :nodoc:
-
-    # Generate code for an element with required start and end tags.
-    #
-    #   - -
-    def nn_element_def(element)
-      nOE_element_def(element, <<-END)
-          if block_given?
-            yield.to_s
-          else
-            ""
-          end +
-          "</#{element.upcase}>"
-      END
-    end
-
-    # Generate code for an empty element.
-    #
-    #   - O EMPTY
-    def nOE_element_def(element, append = nil)
-      s = <<-END
-          attributes={attributes=>nil} if attributes.kind_of?(String)
-          "<#{element.upcase}" + attributes.collect{|name, value|
-            next unless value
-            " " + CGI::escapeHTML(name.to_s) +
-            if true == value
-              ""
-            else
-              '="' + CGI::escapeHTML(value.to_s) + '"'
-            end
-          }.join + ">"
-      END
-      s.sub!(/\Z/, " +") << append if append
-      s
-    end
-
-    # Generate code for an element for which the end (and possibly the
-    # start) tag is optional.
-    #
-    #   O O or - O
-    def nO_element_def(element)
-      nOE_element_def(element, <<-END)
-          if block_given?
-            yield.to_s + "</#{element.upcase}>"
-          else
-            ""
-          end
-      END
-    end
-
-  end # TagMaker
-
-
-  #
-  # Mixin module providing HTML generation methods.
-  #
-  # For example,
-  #   cgi.a("http://www.example.com") { "Example" }
-  #     # => "<A HREF=\"http://www.example.com\">Example</A>"
-  #
-  # Modules Http3, Http4, etc., contain more basic HTML-generation methods
-  # (:title, :center, etc.).
-  #
-  # See class CGI for a detailed example.
-  #
-  module HtmlExtension
-
-
-    # Generate an Anchor element as a string.
-    #
-    # +href+ can either be a string, giving the URL
-    # for the HREF attribute, or it can be a hash of
-    # the element's attributes.
-    #
-    # The body of the element is the string returned by the no-argument
-    # block passed in.
-    #
-    #   a("http://www.example.com") { "Example" }
-    #     # => "<A HREF=\"http://www.example.com\">Example</A>"
-    #
-    #   a("HREF" => "http://www.example.com", "TARGET" => "_top") { "Example" }
-    #     # => "<A HREF=\"http://www.example.com\" TARGET=\"_top\">Example</A>"
-    #
-    def a(href = "") # :yield:
-      attributes = if href.kind_of?(String)
-                     { "HREF" => href }
-                   else
-                     href
-                   end
-      if block_given?
-        super(attributes){ yield }
-      else
-        super(attributes)
-      end
-    end
-
-    # Generate a Document Base URI element as a String.
-    #
-    # +href+ can either by a string, giving the base URL for the HREF
-    # attribute, or it can be a has of the element's attributes.
-    #
-    # The passed-in no-argument block is ignored.
-    #
-    #   base("http://www.example.com/cgi")
-    #     # => "<BASE HREF=\"http://www.example.com/cgi\">"
-    def base(href = "") # :yield:
-      attributes = if href.kind_of?(String)
-                     { "HREF" => href }
-                   else
-                     href
-                   end
-      if block_given?
-        super(attributes){ yield }
-      else
-        super(attributes)
-      end
-    end
-
-    # Generate a BlockQuote element as a string.
-    #
-    # +cite+ can either be a string, give the URI for the source of
-    # the quoted text, or a hash, giving all attributes of the element,
-    # or it can be omitted, in which case the element has no attributes.
-    #
-    # The body is provided by the passed-in no-argument block
-    #
-    #   blockquote("http://www.example.com/quotes/foo.html") { "Foo!" }
-    #     #=> "<BLOCKQUOTE CITE=\"http://www.example.com/quotes/foo.html\">Foo!</BLOCKQUOTE>
-    def blockquote(cite = {})  # :yield:
-      attributes = if cite.kind_of?(String)
-                     { "CITE" => cite }
-                   else
-                     cite
-                   end
-      if block_given?
-        super(attributes){ yield }
-      else
-        super(attributes)
-      end
-    end
-
-
-    # Generate a Table Caption element as a string.
-    #
-    # +align+ can be a string, giving the alignment of the caption
-    # (one of top, bottom, left, or right).  It can be a hash of
-    # all the attributes of the element.  Or it can be omitted.
-    #
-    # The body of the element is provided by the passed-in no-argument block.
-    #
-    #   caption("left") { "Capital Cities" }
-    #     # => <CAPTION ALIGN=\"left\">Capital Cities</CAPTION>
-    def caption(align = {}) # :yield:
-      attributes = if align.kind_of?(String)
-                     { "ALIGN" => align }
-                   else
-                     align
-                   end
-      if block_given?
-        super(attributes){ yield }
-      else
-        super(attributes)
-      end
-    end
-
-
-    # Generate a Checkbox Input element as a string.
-    #
-    # The attributes of the element can be specified as three arguments,
-    # +name+, +value+, and +checked+.  +checked+ is a boolean value;
-    # if true, the CHECKED attribute will be included in the element.
-    #
-    # Alternatively, the attributes can be specified as a hash.
-    #
-    #   checkbox("name")
-    #     # = checkbox("NAME" => "name")
-    #
-    #   checkbox("name", "value")
-    #     # = checkbox("NAME" => "name", "VALUE" => "value")
-    #
-    #   checkbox("name", "value", true)
-    #     # = checkbox("NAME" => "name", "VALUE" => "value", "CHECKED" => true)
-    def checkbox(name = "", value = nil, checked = nil)
-      attributes = if name.kind_of?(String)
-                     { "TYPE" => "checkbox", "NAME" => name,
-                       "VALUE" => value, "CHECKED" => checked }
-                   else
-                     name["TYPE"] = "checkbox"
-                     name
-                   end
-      input(attributes)
-    end
-
-    # Generate a sequence of checkbox elements, as a String.
-    #
-    # The checkboxes will all have the same +name+ attribute.
-    # Each checkbox is followed by a label.
-    # There will be one checkbox for each value.  Each value
-    # can be specified as a String, which will be used both
-    # as the value of the VALUE attribute and as the label
-    # for that checkbox.  A single-element array has the
-    # same effect.
-    #
-    # Each value can also be specified as a three-element array.
-    # The first element is the VALUE attribute; the second is the
-    # label; and the third is a boolean specifying whether this
-    # checkbox is CHECKED.
-    #
-    # Each value can also be specified as a two-element
-    # array, by omitting either the value element (defaults
-    # to the same as the label), or the boolean checked element
-    # (defaults to false).
-    #
-    #   checkbox_group("name", "foo", "bar", "baz")
-    #     # <INPUT TYPE="checkbox" NAME="name" VALUE="foo">foo
-    #     # <INPUT TYPE="checkbox" NAME="name" VALUE="bar">bar
-    #     # <INPUT TYPE="checkbox" NAME="name" VALUE="baz">baz
-    #
-    #   checkbox_group("name", ["foo"], ["bar", true], "baz")
-    #     # <INPUT TYPE="checkbox" NAME="name" VALUE="foo">foo
-    #     # <INPUT TYPE="checkbox" CHECKED NAME="name" VALUE="bar">bar
-    #     # <INPUT TYPE="checkbox" NAME="name" VALUE="baz">baz
-    #
-    #   checkbox_group("name", ["1", "Foo"], ["2", "Bar", true], "Baz")
-    #     # <INPUT TYPE="checkbox" NAME="name" VALUE="1">Foo
-    #     # <INPUT TYPE="checkbox" CHECKED NAME="name" VALUE="2">Bar
-    #     # <INPUT TYPE="checkbox" NAME="name" VALUE="Baz">Baz
-    #
-    #   checkbox_group("NAME" => "name",
-    #                    "VALUES" => ["foo", "bar", "baz"])
-    #
-    #   checkbox_group("NAME" => "name",
-    #                    "VALUES" => [["foo"], ["bar", true], "baz"])
-    #
-    #   checkbox_group("NAME" => "name",
-    #                    "VALUES" => [["1", "Foo"], ["2", "Bar", true], "Baz"])
-    def checkbox_group(name = "", *values)
-      if name.kind_of?(Hash)
-        values = name["VALUES"]
-        name = name["NAME"]
-      end
-      values.collect{|value|
-        if value.kind_of?(String)
-          checkbox(name, value) + value
-        else
-          if value[-1] == true || value[-1] == false
-            checkbox(name, value[0],  value[-1]) +
-            value[-2]
-          else
-            checkbox(name, value[0]) +
-            value[-1]
-          end
-        end
-      }.join
-    end
-
-
-    # Generate an File Upload Input element as a string.
-    #
-    # The attributes of the element can be specified as three arguments,
-    # +name+, +size+, and +maxlength+.  +maxlength+ is the maximum length
-    # of the file's _name_, not of the file's _contents_.
-    #
-    # Alternatively, the attributes can be specified as a hash.
-    #
-    # See #multipart_form() for forms that include file uploads.
-    #
-    #   file_field("name")
-    #     # <INPUT TYPE="file" NAME="name" SIZE="20">
-    #
-    #   file_field("name", 40)
-    #     # <INPUT TYPE="file" NAME="name" SIZE="40">
-    #
-    #   file_field("name", 40, 100)
-    #     # <INPUT TYPE="file" NAME="name" SIZE="40" MAXLENGTH="100">
-    #
-    #   file_field("NAME" => "name", "SIZE" => 40)
-    #     # <INPUT TYPE="file" NAME="name" SIZE="40">
-    def file_field(name = "", size = 20, maxlength = nil)
-      attributes = if name.kind_of?(String)
-                     { "TYPE" => "file", "NAME" => name,
-                       "SIZE" => size.to_s }
-                   else
-                     name["TYPE"] = "file"
-                     name
-                   end
-      attributes["MAXLENGTH"] = maxlength.to_s if maxlength
-      input(attributes)
-    end
-
-
-    # Generate a Form element as a string.
-    #
-    # +method+ should be either "get" or "post", and defaults to the latter.
-    # +action+ defaults to the current CGI script name.  +enctype+
-    # defaults to "application/x-www-form-urlencoded".
-    #
-    # Alternatively, the attributes can be specified as a hash.
-    #
-    # See also #multipart_form() for forms that include file uploads.
-    #
-    #   form{ "string" }
-    #     # <FORM METHOD="post" ENCTYPE="application/x-www-form-urlencoded">string</FORM>
-    #
-    #   form("get") { "string" }
-    #     # <FORM METHOD="get" ENCTYPE="application/x-www-form-urlencoded">string</FORM>
-    #
-    #   form("get", "url") { "string" }
-    #     # <FORM METHOD="get" ACTION="url" ENCTYPE="application/x-www-form-urlencoded">string</FORM>
-    #
-    #   form("METHOD" => "post", "ENCTYPE" => "enctype") { "string" }
-    #     # <FORM METHOD="post" ENCTYPE="enctype">string</FORM>
-    def form(method = "post", action = script_name, enctype = "application/x-www-form-urlencoded")
-      attributes = if method.kind_of?(String)
-                     { "METHOD" => method, "ACTION" => action,
-                       "ENCTYPE" => enctype }
-                   else
-                     unless method.has_key?("METHOD")
-                       method["METHOD"] = "post"
-                     end
-                     unless method.has_key?("ENCTYPE")
-                       method["ENCTYPE"] = enctype
-                     end
-                     method
-                   end
-      if block_given?
-        body = yield
-      else
-        body = ""
-      end
-      if @output_hidden
-        body += @output_hidden.collect{|k,v|
-          "<INPUT TYPE=\"HIDDEN\" NAME=\"#{k}\" VALUE=\"#{v}\">"
-        }.join
-      end
-      super(attributes){body}
-    end
-
-    # Generate a Hidden Input element as a string.
-    #
-    # The attributes of the element can be specified as two arguments,
-    # +name+ and +value+.
-    #
-    # Alternatively, the attributes can be specified as a hash.
-    #
-    #   hidden("name")
-    #     # <INPUT TYPE="hidden" NAME="name">
-    #
-    #   hidden("name", "value")
-    #     # <INPUT TYPE="hidden" NAME="name" VALUE="value">
-    #
-    #   hidden("NAME" => "name", "VALUE" => "reset", "ID" => "foo")
-    #     # <INPUT TYPE="hidden" NAME="name" VALUE="value" ID="foo">
-    def hidden(name = "", value = nil)
-      attributes = if name.kind_of?(String)
-                     { "TYPE" => "hidden", "NAME" => name, "VALUE" => value }
-                   else
-                     name["TYPE"] = "hidden"
-                     name
-                   end
-      input(attributes)
-    end
-
-    # Generate a top-level HTML element as a string.
-    #
-    # The attributes of the element are specified as a hash.  The
-    # pseudo-attribute "PRETTY" can be used to specify that the generated
-    # HTML string should be indented.  "PRETTY" can also be specified as
-    # a string as the sole argument to this method.  The pseudo-attribute
-    # "DOCTYPE", if given, is used as the leading DOCTYPE SGML tag; it
-    # should include the entire text of this tag, including angle brackets.
-    #
-    # The body of the html element is supplied as a block.
-    #
-    #   html{ "string" }
-    #     # <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><HTML>string</HTML>
-    #
-    #   html("LANG" => "ja") { "string" }
-    #     # <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><HTML LANG="ja">string</HTML>
-    #
-    #   html("DOCTYPE" => false) { "string" }
-    #     # <HTML>string</HTML>
-    #
-    #   html("DOCTYPE" => '<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">') { "string" }
-    #     # <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN"><HTML>string</HTML>
-    #
-    #   html("PRETTY" => "  ") { "<BODY></BODY>" }
-    #     # <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
-    #     # <HTML>
-    #     #   <BODY>
-    #     #   </BODY>
-    #     # </HTML>
-    #
-    #   html("PRETTY" => "\t") { "<BODY></BODY>" }
-    #     # <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
-    #     # <HTML>
-    #     #         <BODY>
-    #     #         </BODY>
-    #     # </HTML>
-    #
-    #   html("PRETTY") { "<BODY></BODY>" }
-    #     # = html("PRETTY" => "  ") { "<BODY></BODY>" }
-    #
-    #   html(if $VERBOSE then "PRETTY" end) { "HTML string" }
-    #
-    def html(attributes = {}) # :yield:
-      if nil == attributes
-        attributes = {}
-      elsif "PRETTY" == attributes
-        attributes = { "PRETTY" => true }
-      end
-      pretty = attributes.delete("PRETTY")
-      pretty = "  " if true == pretty
-      buf = ""
-
-      if attributes.has_key?("DOCTYPE")
-        if attributes["DOCTYPE"]
-          buf += attributes.delete("DOCTYPE")
-        else
-          attributes.delete("DOCTYPE")
-        end
-      else
-        buf += doctype
-      end
-
-      if block_given?
-        buf += super(attributes){ yield }
-      else
-        buf += super(attributes)
-      end
-
-      if pretty
-        CGI::pretty(buf, pretty)
-      else
-        buf
-      end
-
-    end
-
-    # Generate an Image Button Input element as a string.
-    #
-    # +src+ is the URL of the image to use for the button.  +name+
-    # is the input name.  +alt+ is the alternative text for the image.
-    #
-    # Alternatively, the attributes can be specified as a hash.
-    #
-    #   image_button("url")
-    #     # <INPUT TYPE="image" SRC="url">
-    #
-    #   image_button("url", "name", "string")
-    #     # <INPUT TYPE="image" SRC="url" NAME="name" ALT="string">
-    #
-    #   image_button("SRC" => "url", "ALT" => "string")
-    #     # <INPUT TYPE="image" SRC="url" ALT="string">
-    def image_button(src = "", name = nil, alt = nil)
-      attributes = if src.kind_of?(String)
-                     { "TYPE" => "image", "SRC" => src, "NAME" => name,
-                       "ALT" => alt }
-                   else
-                     src["TYPE"] = "image"
-                     src["SRC"] ||= ""
-                     src
-                   end
-      input(attributes)
-    end
-
-
-    # Generate an Image element as a string.
-    #
-    # +src+ is the URL of the image.  +alt+ is the alternative text for
-    # the image.  +width+ is the width of the image, and +height+ is
-    # its height.
-    #
-    # Alternatively, the attributes can be specified as a hash.
-    #
-    #   img("src", "alt", 100, 50)
-    #     # <IMG SRC="src" ALT="alt" WIDTH="100" HEIGHT="50">
-    #
-    #   img("SRC" => "src", "ALT" => "alt", "WIDTH" => 100, "HEIGHT" => 50)
-    #     # <IMG SRC="src" ALT="alt" WIDTH="100" HEIGHT="50">
-    def img(src = "", alt = "", width = nil, height = nil)
-      attributes = if src.kind_of?(String)
-                     { "SRC" => src, "ALT" => alt }
-                   else
-                     src
-                   end
-      attributes["WIDTH"] = width.to_s if width
-      attributes["HEIGHT"] = height.to_s if height
-      super(attributes)
-    end
-
-
-    # Generate a Form element with multipart encoding as a String.
-    #
-    # Multipart encoding is used for forms that include file uploads.
-    #
-    # +action+ is the action to perform.  +enctype+ is the encoding
-    # type, which defaults to "multipart/form-data".
-    #
-    # Alternatively, the attributes can be specified as a hash.
-    #
-    #   multipart_form{ "string" }
-    #     # <FORM METHOD="post" ENCTYPE="multipart/form-data">string</FORM>
-    #
-    #   multipart_form("url") { "string" }
-    #     # <FORM METHOD="post" ACTION="url" ENCTYPE="multipart/form-data">string</FORM>
-    def multipart_form(action = nil, enctype = "multipart/form-data")
-      attributes = if action == nil
-                     { "METHOD" => "post", "ENCTYPE" => enctype }
-                   elsif action.kind_of?(String)
-                     { "METHOD" => "post", "ACTION" => action,
-                       "ENCTYPE" => enctype }
-                   else
-                     unless action.has_key?("METHOD")
-                       action["METHOD"] = "post"
-                     end
-                     unless action.has_key?("ENCTYPE")
-                       action["ENCTYPE"] = enctype
-                     end
-                     action
-                   end
-      if block_given?
-        form(attributes){ yield }
-      else
-        form(attributes)
-      end
-    end
-
-
-    # Generate a Password Input element as a string.
-    #
-    # +name+ is the name of the input field.  +value+ is its default
-    # value.  +size+ is the size of the input field display.  +maxlength+
-    # is the maximum length of the inputted password.
-    #
-    # Alternatively, attributes can be specified as a hash.
-    #
-    #   password_field("name")
-    #     # <INPUT TYPE="password" NAME="name" SIZE="40">
-    #
-    #   password_field("name", "value")
-    #     # <INPUT TYPE="password" NAME="name" VALUE="value" SIZE="40">
-    #
-    #   password_field("password", "value", 80, 200)
-    #     # <INPUT TYPE="password" NAME="name" VALUE="value" SIZE="80" MAXLENGTH="200">
-    #
-    #   password_field("NAME" => "name", "VALUE" => "value")
-    #     # <INPUT TYPE="password" NAME="name" VALUE="value">
-    def password_field(name = "", value = nil, size = 40, maxlength = nil)
-      attributes = if name.kind_of?(String)
-                     { "TYPE" => "password", "NAME" => name,
-                       "VALUE" => value, "SIZE" => size.to_s }
-                   else
-                     name["TYPE"] = "password"
-                     name
-                   end
-      attributes["MAXLENGTH"] = maxlength.to_s if maxlength
-      input(attributes)
-    end
-
-    # Generate a Select element as a string.
-    #
-    # +name+ is the name of the element.  The +values+ are the options that
-    # can be selected from the Select menu.  Each value can be a String or
-    # a one, two, or three-element Array.  If a String or a one-element
-    # Array, this is both the value of that option and the text displayed for
-    # it.  If a three-element Array, the elements are the option value, displayed
-    # text, and a boolean value specifying whether this option starts as selected.
-    # The two-element version omits either the option value (defaults to the same
-    # as the display text) or the boolean selected specifier (defaults to false).
-    #
-    # The attributes and options can also be specified as a hash.  In this
-    # case, options are specified as an array of values as described above,
-    # with the hash key of "VALUES".
-    #
-    #   popup_menu("name", "foo", "bar", "baz")
-    #     # <SELECT NAME="name">
-    #     #   <OPTION VALUE="foo">foo</OPTION>
-    #     #   <OPTION VALUE="bar">bar</OPTION>
-    #     #   <OPTION VALUE="baz">baz</OPTION>
-    #     # </SELECT>
-    #
-    #   popup_menu("name", ["foo"], ["bar", true], "baz")
-    #     # <SELECT NAME="name">
-    #     #   <OPTION VALUE="foo">foo</OPTION>
-    #     #   <OPTION VALUE="bar" SELECTED>bar</OPTION>
-    #     #   <OPTION VALUE="baz">baz</OPTION>
-    #     # </SELECT>
-    #
-    #   popup_menu("name", ["1", "Foo"], ["2", "Bar", true], "Baz")
-    #     # <SELECT NAME="name">
-    #     #   <OPTION VALUE="1">Foo</OPTION>
-    #     #   <OPTION SELECTED VALUE="2">Bar</OPTION>
-    #     #   <OPTION VALUE="Baz">Baz</OPTION>
-    #     # </SELECT>
-    #
-    #   popup_menu("NAME" => "name", "SIZE" => 2, "MULTIPLE" => true,
-    #               "VALUES" => [["1", "Foo"], ["2", "Bar", true], "Baz"])
-    #     # <SELECT NAME="name" MULTIPLE SIZE="2">
-    #     #   <OPTION VALUE="1">Foo</OPTION>
-    #     #   <OPTION SELECTED VALUE="2">Bar</OPTION>
-    #     #   <OPTION VALUE="Baz">Baz</OPTION>
-    #     # </SELECT>
-    def popup_menu(name = "", *values)
-
-      if name.kind_of?(Hash)
-        values   = name["VALUES"]
-        size     = name["SIZE"].to_s if name["SIZE"]
-        multiple = name["MULTIPLE"]
-        name     = name["NAME"]
-      else
-        size = nil
-        multiple = nil
-      end
-
-      select({ "NAME" => name, "SIZE" => size,
-               "MULTIPLE" => multiple }){
-        values.collect{|value|
-          if value.kind_of?(String)
-            option({ "VALUE" => value }){ value }
-          else
-            if value[value.size - 1] == true
-              option({ "VALUE" => value[0], "SELECTED" => true }){
-                value[value.size - 2]
-              }
-            else
-              option({ "VALUE" => value[0] }){
-                value[value.size - 1]
-              }
-            end
-          end
-        }.join
-      }
-
-    end
-
-    # Generates a radio-button Input element.
-    #
-    # +name+ is the name of the input field.  +value+ is the value of
-    # the field if checked.  +checked+ specifies whether the field
-    # starts off checked.
-    #
-    # Alternatively, the attributes can be specified as a hash.
-    #
-    #   radio_button("name", "value")
-    #     # <INPUT TYPE="radio" NAME="name" VALUE="value">
-    #
-    #   radio_button("name", "value", true)
-    #     # <INPUT TYPE="radio" NAME="name" VALUE="value" CHECKED>
-    #
-    #   radio_button("NAME" => "name", "VALUE" => "value", "ID" => "foo")
-    #     # <INPUT TYPE="radio" NAME="name" VALUE="value" ID="foo">
-    def radio_button(name = "", value = nil, checked = nil)
-      attributes = if name.kind_of?(String)
-                     { "TYPE" => "radio", "NAME" => name,
-                       "VALUE" => value, "CHECKED" => checked }
-                   else
-                     name["TYPE"] = "radio"
-                     name
-                   end
-      input(attributes)
-    end
-
-    # Generate a sequence of radio button Input elements, as a String.
-    #
-    # This works the same as #checkbox_group().  However, it is not valid
-    # to have more than one radiobutton in a group checked.
-    #
-    #   radio_group("name", "foo", "bar", "baz")
-    #     # <INPUT TYPE="radio" NAME="name" VALUE="foo">foo
-    #     # <INPUT TYPE="radio" NAME="name" VALUE="bar">bar
-    #     # <INPUT TYPE="radio" NAME="name" VALUE="baz">baz
-    #
-    #   radio_group("name", ["foo"], ["bar", true], "baz")
-    #     # <INPUT TYPE="radio" NAME="name" VALUE="foo">foo
-    #     # <INPUT TYPE="radio" CHECKED NAME="name" VALUE="bar">bar
-    #     # <INPUT TYPE="radio" NAME="name" VALUE="baz">baz
-    #
-    #   radio_group("name", ["1", "Foo"], ["2", "Bar", true], "Baz")
-    #     # <INPUT TYPE="radio" NAME="name" VALUE="1">Foo
-    #     # <INPUT TYPE="radio" CHECKED NAME="name" VALUE="2">Bar
-    #     # <INPUT TYPE="radio" NAME="name" VALUE="Baz">Baz
-    #
-    #   radio_group("NAME" => "name",
-    #                 "VALUES" => ["foo", "bar", "baz"])
-    #
-    #   radio_group("NAME" => "name",
-    #                 "VALUES" => [["foo"], ["bar", true], "baz"])
-    #
-    #   radio_group("NAME" => "name",
-    #                 "VALUES" => [["1", "Foo"], ["2", "Bar", true], "Baz"])
-    def radio_group(name = "", *values)
-      if name.kind_of?(Hash)
-        values = name["VALUES"]
-        name = name["NAME"]
-      end
-      values.collect{|value|
-        if value.kind_of?(String)
-          radio_button(name, value) + value
-        else
-          if value[-1] == true || value[-1] == false
-            radio_button(name, value[0],  value[-1]) +
-            value[-2]
-          else
-            radio_button(name, value[0]) +
-            value[-1]
-          end
-        end
-      }.join
-    end
-
-    # Generate a reset button Input element, as a String.
-    #
-    # This resets the values on a form to their initial values.  +value+
-    # is the text displayed on the button. +name+ is the name of this button.
-    #
-    # Alternatively, the attributes can be specified as a hash.
-    #
-    #   reset
-    #     # <INPUT TYPE="reset">
-    #
-    #   reset("reset")
-    #     # <INPUT TYPE="reset" VALUE="reset">
-    #
-    #   reset("VALUE" => "reset", "ID" => "foo")
-    #     # <INPUT TYPE="reset" VALUE="reset" ID="foo">
-    def reset(value = nil, name = nil)
-      attributes = if (not value) or value.kind_of?(String)
-                     { "TYPE" => "reset", "VALUE" => value, "NAME" => name }
-                   else
-                     value["TYPE"] = "reset"
-                     value
-                   end
-      input(attributes)
-    end
-
-    alias scrolling_list popup_menu
-
-    # Generate a submit button Input element, as a String.
-    #
-    # +value+ is the text to display on the button.  +name+ is the name
-    # of the input.
-    #
-    # Alternatively, the attributes can be specified as a hash.
-    #
-    #   submit
-    #     # <INPUT TYPE="submit">
-    #
-    #   submit("ok")
-    #     # <INPUT TYPE="submit" VALUE="ok">
-    #
-    #   submit("ok", "button1")
-    #     # <INPUT TYPE="submit" VALUE="ok" NAME="button1">
-    #
-    #   submit("VALUE" => "ok", "NAME" => "button1", "ID" => "foo")
-    #     # <INPUT TYPE="submit" VALUE="ok" NAME="button1" ID="foo">
-    def submit(value = nil, name = nil)
-      attributes = if (not value) or value.kind_of?(String)
-                     { "TYPE" => "submit", "VALUE" => value, "NAME" => name }
-                   else
-                     value["TYPE"] = "submit"
-                     value
-                   end
-      input(attributes)
-    end
-
-    # Generate a text field Input element, as a String.
-    #
-    # +name+ is the name of the input field.  +value+ is its initial
-    # value.  +size+ is the size of the input area.  +maxlength+
-    # is the maximum length of input accepted.
-    #
-    # Alternatively, the attributes can be specified as a hash.
-    #
-    #   text_field("name")
-    #     # <INPUT TYPE="text" NAME="name" SIZE="40">
-    #
-    #   text_field("name", "value")
-    #     # <INPUT TYPE="text" NAME="name" VALUE="value" SIZE="40">
-    #
-    #   text_field("name", "value", 80)
-    #     # <INPUT TYPE="text" NAME="name" VALUE="value" SIZE="80">
-    #
-    #   text_field("name", "value", 80, 200)
-    #     # <INPUT TYPE="text" NAME="name" VALUE="value" SIZE="80" MAXLENGTH="200">
-    #
-    #   text_field("NAME" => "name", "VALUE" => "value")
-    #     # <INPUT TYPE="text" NAME="name" VALUE="value">
-    def text_field(name = "", value = nil, size = 40, maxlength = nil)
-      attributes = if name.kind_of?(String)
-                     { "TYPE" => "text", "NAME" => name, "VALUE" => value,
-                       "SIZE" => size.to_s }
-                   else
-                     name["TYPE"] = "text"
-                     name
-                   end
-      attributes["MAXLENGTH"] = maxlength.to_s if maxlength
-      input(attributes)
-    end
-
-    # Generate a TextArea element, as a String.
-    #
-    # +name+ is the name of the textarea.  +cols+ is the number of
-    # columns and +rows+ is the number of rows in the display.
-    #
-    # Alternatively, the attributes can be specified as a hash.
-    #
-    # The body is provided by the passed-in no-argument block
-    #
-    #   textarea("name")
-    #      # = textarea("NAME" => "name", "COLS" => 70, "ROWS" => 10)
-    #
-    #   textarea("name", 40, 5)
-    #      # = textarea("NAME" => "name", "COLS" => 40, "ROWS" => 5)
-    def textarea(name = "", cols = 70, rows = 10)  # :yield:
-      attributes = if name.kind_of?(String)
-                     { "NAME" => name, "COLS" => cols.to_s,
-                       "ROWS" => rows.to_s }
-                   else
-                     name
-                   end
-      if block_given?
-        super(attributes){ yield }
-      else
-        super(attributes)
-      end
-    end
-
-  end # HtmlExtension
-
-
-  # Mixin module for HTML version 3 generation methods.
-  module Html3 # :nodoc:
-
-    # The DOCTYPE declaration for this version of HTML
-    def doctype
-      %|<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">|
-    end
-
-    # Initialise the HTML generation methods for this version.
-    def element_init
-      extend TagMaker
-      methods = ""
-      # - -
-      for element in %w[ A TT I B U STRIKE BIG SMALL SUB SUP EM STRONG
-          DFN CODE SAMP KBD VAR CITE FONT ADDRESS DIV center MAP
-          APPLET PRE XMP LISTING DL OL UL DIR MENU SELECT table TITLE
-          STYLE SCRIPT H1 H2 H3 H4 H5 H6 TEXTAREA FORM BLOCKQUOTE
-          CAPTION ]
-        methods += <<-BEGIN + nn_element_def(element) + <<-END
-          def #{element.downcase}(attributes = {})
-        BEGIN
-          end
-        END
-      end
-
-      # - O EMPTY
-      for element in %w[ IMG BASE BASEFONT BR AREA LINK PARAM HR INPUT
-          ISINDEX META ]
-        methods += <<-BEGIN + nOE_element_def(element) + <<-END
-          def #{element.downcase}(attributes = {})
-        BEGIN
-          end
-        END
-      end
-
-      # O O or - O
-      for element in %w[ HTML HEAD BODY P PLAINTEXT DT DD LI OPTION tr
-          th td ]
-        methods += <<-BEGIN + nO_element_def(element) + <<-END
-          def #{element.downcase}(attributes = {})
-        BEGIN
-          end
-        END
-      end
-      eval(methods)
-    end
-
-  end # Html3
-
-
-  # Mixin module for HTML version 4 generation methods.
-  module Html4 # :nodoc:
-
-    # The DOCTYPE declaration for this version of HTML
-    def doctype
-      %|<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">|
-    end
-
-    # Initialise the HTML generation methods for this version.
-    def element_init
-      extend TagMaker
-      methods = ""
-      # - -
-      for element in %w[ TT I B BIG SMALL EM STRONG DFN CODE SAMP KBD
-        VAR CITE ABBR ACRONYM SUB SUP SPAN BDO ADDRESS DIV MAP OBJECT
-        H1 H2 H3 H4 H5 H6 PRE Q INS DEL DL OL UL LABEL SELECT OPTGROUP
-        FIELDSET LEGEND BUTTON TABLE TITLE STYLE SCRIPT NOSCRIPT
-        TEXTAREA FORM A BLOCKQUOTE CAPTION ]
-        methods += <<-BEGIN + nn_element_def(element) + <<-END
-          def #{element.downcase}(attributes = {})
-        BEGIN
-          end
-        END
-      end
-
-      # - O EMPTY
-      for element in %w[ IMG BASE BR AREA LINK PARAM HR INPUT COL META ]
-        methods += <<-BEGIN + nOE_element_def(element) + <<-END
-          def #{element.downcase}(attributes = {})
-        BEGIN
-          end
-        END
-      end
-
-      # O O or - O
-      for element in %w[ HTML BODY P DT DD LI OPTION THEAD TFOOT TBODY
-          COLGROUP TR TH TD HEAD]
-        methods += <<-BEGIN + nO_element_def(element) + <<-END
-          def #{element.downcase}(attributes = {})
-        BEGIN
-          end
-        END
-      end
-      eval(methods)
-    end
-
-  end # Html4
-
-
-  # Mixin module for HTML version 4 transitional generation methods.
-  module Html4Tr # :nodoc:
-
-    # The DOCTYPE declaration for this version of HTML
-    def doctype
-      %|<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">|
-    end
-
-    # Initialise the HTML generation methods for this version.
-    def element_init
-      extend TagMaker
-      methods = ""
-      # - -
-      for element in %w[ TT I B U S STRIKE BIG SMALL EM STRONG DFN
-          CODE SAMP KBD VAR CITE ABBR ACRONYM FONT SUB SUP SPAN BDO
-          ADDRESS DIV CENTER MAP OBJECT APPLET H1 H2 H3 H4 H5 H6 PRE Q
-          INS DEL DL OL UL DIR MENU LABEL SELECT OPTGROUP FIELDSET
-          LEGEND BUTTON TABLE IFRAME NOFRAMES TITLE STYLE SCRIPT
-          NOSCRIPT TEXTAREA FORM A BLOCKQUOTE CAPTION ]
-        methods += <<-BEGIN + nn_element_def(element) + <<-END
-          def #{element.downcase}(attributes = {})
-        BEGIN
-          end
-        END
-      end
-
-      # - O EMPTY
-      for element in %w[ IMG BASE BASEFONT BR AREA LINK PARAM HR INPUT
-          COL ISINDEX META ]
-        methods += <<-BEGIN + nOE_element_def(element) + <<-END
-          def #{element.downcase}(attributes = {})
-        BEGIN
-          end
-        END
-      end
-
-      # O O or - O
-      for element in %w[ HTML BODY P DT DD LI OPTION THEAD TFOOT TBODY
-          COLGROUP TR TH TD HEAD ]
-        methods += <<-BEGIN + nO_element_def(element) + <<-END
-          def #{element.downcase}(attributes = {})
-        BEGIN
-          end
-        END
-      end
-      eval(methods)
-    end
-
-  end # Html4Tr
-
-
-  # Mixin module for generating HTML version 4 with framesets.
-  module Html4Fr # :nodoc:
-
-    # The DOCTYPE declaration for this version of HTML
-    def doctype
-      %|<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "http://www.w3.org/TR/html4/frameset.dtd">|
-    end
-
-    # Initialise the HTML generation methods for this version.
-    def element_init
-      methods = ""
-      # - -
-      for element in %w[ FRAMESET ]
-        methods += <<-BEGIN + nn_element_def(element) + <<-END
-          def #{element.downcase}(attributes = {})
-        BEGIN
-          end
-        END
-      end
-
-      # - O EMPTY
-      for element in %w[ FRAME ]
-        methods += <<-BEGIN + nOE_element_def(element) + <<-END
-          def #{element.downcase}(attributes = {})
-        BEGIN
-          end
-        END
-      end
-      eval(methods)
-    end
-
-  end # Html4Fr
-end
-
-
diff --git a/lib/cgi/session.rb b/lib/cgi/session.rb
deleted file mode 100644
index 42b5ead81a..0000000000
--- a/lib/cgi/session.rb
+++ /dev/null
@@ -1,531 +0,0 @@
-#
-# cgi/session.rb - session support for cgi scripts
-#
-# Copyright (C) 2001  Yukihiro "Matz" Matsumoto
-# Copyright (C) 2000  Network Applied Communication Laboratory, Inc.
-# Copyright (C) 2000  Information-technology Promotion Agency, Japan
-#
-# Author: Yukihiro "Matz" Matsumoto
-#
-# Documentation: William Webber (william@williamwebber.com)
-
-require 'cgi'
-require 'tmpdir'
-
-class CGI
-
-  # == Overview
-  #
-  # This file provides the CGI::Session class, which provides session
-  # support for CGI scripts.  A session is a sequence of HTTP requests
-  # and responses linked together and associated with a single client.
-  # Information associated with the session is stored
-  # on the server between requests.  A session id is passed between client
-  # and server with every request and response, transparently
-  # to the user.  This adds state information to the otherwise stateless
-  # HTTP request/response protocol.
-  #
-  # == Lifecycle
-  #
-  # A CGI::Session instance is created from a CGI object.  By default,
-  # this CGI::Session instance will start a new session if none currently
-  # exists, or continue the current session for this client if one does
-  # exist.  The +new_session+ option can be used to either always or
-  # never create a new session.  See #new() for more details.
-  #
-  # #delete() deletes a session from session storage.  It
-  # does not however remove the session id from the client.  If the client
-  # makes another request with the same id, the effect will be to start
-  # a new session with the old session's id.
-  #
-  # == Setting and retrieving session data.
-  #
-  # The Session class associates data with a session as key-value pairs.
-  # This data can be set and retrieved by indexing the Session instance
-  # using '[]', much the same as hashes (although other hash methods
-  # are not supported).
-  #
-  # When session processing has been completed for a request, the
-  # session should be closed using the close() method.  This will
-  # store the session's state to persistent storage.  If you want
-  # to store the session's state to persistent storage without
-  # finishing session processing for this request, call the update()
-  # method.
-  #
-  # == Storing session state
-  #
-  # The caller can specify what form of storage to use for the session's
-  # data with the +database_manager+ option to CGI::Session::new.  The
-  # following storage classes are provided as part of the standard library:
-  #
-  # CGI::Session::FileStore:: stores data as plain text in a flat file.  Only
-  #                           works with String data.  This is the default
-  #                           storage type.
-  # CGI::Session::MemoryStore:: stores data in an in-memory hash.  The data
-  #                             only persists for as long as the current ruby
-  #                             interpreter instance does.
-  # CGI::Session::PStore:: stores data in Marshalled format.  Provided by
-  #                        cgi/session/pstore.rb.  Supports data of any type,
-  #                        and provides file-locking and transaction support.
-  #
-  # Custom storage types can also be created by defining a class with
-  # the following methods:
-  #
-  #    new(session, options)
-  #    restore  # returns hash of session data.
-  #    update
-  #    close
-  #    delete
-  #
-  # Changing storage type mid-session does not work.  Note in particular
-  # that by default the FileStore and PStore session data files have the
-  # same name.  If your application switches from one to the other without
-  # making sure that filenames will be different
-  # and clients still have old sessions lying around in cookies, then
-  # things will break nastily!
-  #
-  # == Maintaining the session id.
-  #
-  # Most session state is maintained on the server.  However, a session
-  # id must be passed backwards and forwards between client and server
-  # to maintain a reference to this session state.
-  #
-  # The simplest way to do this is via cookies.  The CGI::Session class
-  # provides transparent support for session id communication via cookies
-  # if the client has cookies enabled.
-  #
-  # If the client has cookies disabled, the session id must be included
-  # as a parameter of all requests sent by the client to the server.  The
-  # CGI::Session class in conjunction with the CGI class will transparently
-  # add the session id as a hidden input field to all forms generated
-  # using the CGI#form() HTML generation method.  No built-in support is
-  # provided for other mechanisms, such as URL re-writing.  The caller is
-  # responsible for extracting the session id from the session_id
-  # attribute and manually encoding it in URLs and adding it as a hidden
-  # input to HTML forms created by other mechanisms.  Also, session expiry
-  # is not automatically handled.
-  #
-  # == Examples of use
-  #
-  # === Setting the user's name
-  #
-  #   require 'cgi'
-  #   require 'cgi/session'
-  #   require 'cgi/session/pstore'     # provides CGI::Session::PStore
-  #
-  #   cgi = CGI.new("html4")
-  #
-  #   session = CGI::Session.new(cgi,
-  #       'database_manager' => CGI::Session::PStore,  # use PStore
-  #       'session_key' => '_rb_sess_id',              # custom session key
-  #       'session_expires' => Time.now + 30 * 60,     # 30 minute timeout
-  #       'prefix' => 'pstore_sid_')                   # PStore option
-  #   if cgi.has_key?('user_name') and cgi['user_name'] != ''
-  #       # coerce to String: cgi[] returns the
-  #       # string-like CGI::QueryExtension::Value
-  #       session['user_name'] = cgi['user_name'].to_s
-  #   elsif !session['user_name']
-  #       session['user_name'] = "guest"
-  #   end
-  #   session.close
-  #
-  # === Creating a new session safely
-  #
-  #   require 'cgi'
-  #   require 'cgi/session'
-  #
-  #   cgi = CGI.new("html4")
-  #
-  #   # We make sure to delete an old session if one exists,
-  #   # not just to free resources, but to prevent the session
-  #   # from being maliciously hijacked later on.
-  #   begin
-  #       session = CGI::Session.new(cgi, 'new_session' => false)
-  #       session.delete
-  #   rescue ArgumentError  # if no old session
-  #   end
-  #   session = CGI::Session.new(cgi, 'new_session' => true)
-  #   session.close
-  #
-  class Session
-
-    class NoSession < RuntimeError #:nodoc:
-    end
-
-    # The id of this session.
-    attr_reader :session_id, :new_session
-
-    def Session::callback(dbman)  #:nodoc:
-      Proc.new{
-        dbman[0].close unless dbman.empty?
-      }
-    end
-
-    # Create a new session id.
-    #
-    # The session id is an MD5 hash based upon the time,
-    # a random number, and a constant string.  This routine
-    # is used internally for automatically generated
-    # session ids.
-    def create_new_id
-      require 'securerandom'
-      begin
-        session_id = SecureRandom.hex(16)
-      rescue NotImplementedError
-        require 'digest/md5'
-        md5 = Digest::MD5::new
-        now = Time::now
-        md5.update(now.to_s)
-        md5.update(String(now.usec))
-        md5.update(String(rand(0)))
-        md5.update(String($$))
-        md5.update('foobar')
-        session_id = md5.hexdigest
-      end
-      session_id
-    end
-    private :create_new_id
-
-    # Create a new CGI::Session object for +request+.
-    #
-    # +request+ is an instance of the +CGI+ class (see cgi.rb).
-    # +option+ is a hash of options for initialising this
-    # CGI::Session instance.  The following options are
-    # recognised:
-    #
-    # session_key:: the parameter name used for the session id.
-    #               Defaults to '_session_id'.
-    # session_id:: the session id to use.  If not provided, then
-    #              it is retrieved from the +session_key+ parameter
-    #              of the request, or automatically generated for
-    #              a new session.
-    # new_session:: if true, force creation of a new session.  If not set,
-    #               a new session is only created if none currently
-    #               exists.  If false, a new session is never created,
-    #               and if none currently exists and the +session_id+
-    #               option is not set, an ArgumentError is raised.
-    # database_manager:: the name of the class providing storage facilities
-    #                    for session state persistence.  Built-in support
-    #                    is provided for +FileStore+ (the default),
-    #                    +MemoryStore+, and +PStore+ (from
-    #                    cgi/session/pstore.rb).  See the documentation for
-    #                    these classes for more details.
-    #
-    # The following options are also recognised, but only apply if the
-    # session id is stored in a cookie.
-    #
-    # session_expires:: the time the current session expires, as a
-    #                   +Time+ object.  If not set, the session will terminate
-    #                   when the user's browser is closed.
-    # session_domain:: the hostname domain for which this session is valid.
-    #                  If not set, defaults to the hostname of the server.
-    # session_secure:: if +true+, this session will only work over HTTPS.
-    # session_path:: the path for which this session applies.  Defaults
-    #                to the directory of the CGI script.
-    #
-    # +option+ is also passed on to the session storage class initializer; see
-    # the documentation for each session storage class for the options
-    # they support.
-    #
-    # The retrieved or created session is automatically added to +request+
-    # as a cookie, and also to its +output_hidden+ table, which is used
-    # to add hidden input elements to forms.
-    #
-    # *WARNING* the +output_hidden+
-    # fields are surrounded by a <fieldset> tag in HTML 4 generation, which
-    # is _not_ invisible on many browsers; you may wish to disable the
-    # use of fieldsets with code similar to the following
-    # (see http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-list/37805)
-    #
-    #   cgi = CGI.new("html4")
-    #   class << cgi
-    #       undef_method :fieldset
-    #   end
-    #
-    def initialize(request, option={})
-      @new_session = false
-      session_key = option['session_key'] || '_session_id'
-      session_id = option['session_id']
-      unless session_id
-        if option['new_session']
-          session_id = create_new_id
-          @new_session = true
-        end
-      end
-      unless session_id
-        if request.key?(session_key)
-          session_id = request[session_key]
-          session_id = session_id.read if session_id.respond_to?(:read)
-        end
-        unless session_id
-          session_id, = request.cookies[session_key]
-        end
-        unless session_id
-          unless option.fetch('new_session', true)
-            raise ArgumentError, "session_key `%s' should be supplied"%session_key
-          end
-          session_id = create_new_id
-          @new_session = true
-        end
-      end
-      @session_id = session_id
-      dbman = option['database_manager'] || FileStore
-      begin
-        @dbman = dbman::new(self, option)
-      rescue NoSession
-        unless option.fetch('new_session', true)
-          raise ArgumentError, "invalid session_id `%s'"%session_id
-        end
-        session_id = @session_id = create_new_id unless session_id
-        @new_session=true
-        retry
-      end
-      request.instance_eval do
-        @output_hidden = {session_key => session_id} unless option['no_hidden']
-        @output_cookies =  [
-          Cookie::new("name" => session_key,
-          "value" => session_id,
-          "expires" => option['session_expires'],
-          "domain" => option['session_domain'],
-          "secure" => option['session_secure'],
-          "path" =>
-          if option['session_path']
-            option['session_path']
-          elsif ENV["SCRIPT_NAME"]
-            File::dirname(ENV["SCRIPT_NAME"])
-          else
-          ""
-          end)
-        ] unless option['no_cookies']
-      end
-      @dbprot = [@dbman]
-      ObjectSpace::define_finalizer(self, Session::callback(@dbprot))
-    end
-
-    # Retrieve the session data for key +key+.
-    def [](key)
-      @data ||= @dbman.restore
-      @data[key]
-    end
-
-    # Set the session date for key +key+.
-    def []=(key, val)
-      @write_lock ||= true
-      @data ||= @dbman.restore
-      @data[key] = val
-    end
-
-    # Store session data on the server.  For some session storage types,
-    # this is a no-op.
-    def update
-      @dbman.update
-    end
-
-    # Store session data on the server and close the session storage.
-    # For some session storage types, this is a no-op.
-    def close
-      @dbman.close
-      @dbprot.clear
-    end
-
-    # Delete the session from storage.  Also closes the storage.
-    #
-    # Note that the session's data is _not_ automatically deleted
-    # upon the session expiring.
-    def delete
-      @dbman.delete
-      @dbprot.clear
-    end
-
-    # File-based session storage class.
-    #
-    # Implements session storage as a flat file of 'key=value' values.
-    # This storage type only works directly with String values; the
-    # user is responsible for converting other types to Strings when
-    # storing and from Strings when retrieving.
-    class FileStore
-      # Create a new FileStore instance.
-      #
-      # This constructor is used internally by CGI::Session.  The
-      # user does not generally need to call it directly.
-      #
-      # +session+ is the session for which this instance is being
-      # created.  The session id must only contain alphanumeric
-      # characters; automatically generated session ids observe
-      # this requirement.
-      #
-      # +option+ is a hash of options for the initializer.  The
-      # following options are recognised:
-      #
-      # tmpdir:: the directory to use for storing the FileStore
-      #          file.  Defaults to Dir::tmpdir (generally "/tmp"
-      #          on Unix systems).
-      # prefix:: the prefix to add to the session id when generating
-      #          the filename for this session's FileStore file.
-      #          Defaults to "cgi_sid_".
-      # suffix:: the prefix to add to the session id when generating
-      #          the filename for this session's FileStore file.
-      #          Defaults to the empty string.
-      #
-      # This session's FileStore file will be created if it does
-      # not exist, or opened if it does.
-      def initialize(session, option={})
-        dir = option['tmpdir'] || Dir::tmpdir
-        prefix = option['prefix'] || 'cgi_sid_'
-        suffix = option['suffix'] || ''
-        id = session.session_id
-        require 'digest/md5'
-        md5 = Digest::MD5.hexdigest(id)[0,16]
-        @path = dir+"/"+prefix+md5+suffix
-        if File::exist? @path
-          @hash = nil
-        else
-          unless session.new_session
-            raise CGI::Session::NoSession, "uninitialized session"
-          end
-          @hash = {}
-        end
-      end
-
-      # Restore session state from the session's FileStore file.
-      #
-      # Returns the session state as a hash.
-      def restore
-        unless @hash
-          @hash = {}
-          begin
-            lockf = File.open(@path+".lock", "r")
-            lockf.flock File::LOCK_SH
-            f = File.open(@path, 'r')
-            for line in f
-              line.chomp!
-              k, v = line.split('=',2)
-              @hash[CGI::unescape(k)] = Marshal.restore(CGI::unescape(v))
-            end
-          ensure
-            f.close unless f.nil?
-            lockf.close if lockf
-          end
-        end
-        @hash
-      end
-
-      # Save session state to the session's FileStore file.
-      def update
-        return unless @hash
-        begin
-          lockf = File.open(@path+".lock", File::CREAT|File::RDWR, 0600)
-          lockf.flock File::LOCK_EX
-          f = File.open(@path+".new", File::CREAT|File::TRUNC|File::WRONLY, 0600)
-          for k,v in @hash
-            f.printf "%s=%s\n", CGI::escape(k), CGI::escape(String(Marshal.dump(v)))
-          end
-          f.close
-          File.rename @path+".new", @path
-        ensure
-          f.close if f and !f.closed?
-          lockf.close if lockf
-        end
-      end
-
-      # Update and close the session's FileStore file.
-      def close
-        update
-      end
-
-      # Close and delete the session's FileStore file.
-      def delete
-        File::unlink @path+".lock" rescue nil
-        File::unlink @path+".new" rescue nil
-        File::unlink @path rescue Errno::ENOENT
-      end
-    end
-
-    # In-memory session storage class.
-    #
-    # Implements session storage as a global in-memory hash.  Session
-    # data will only persist for as long as the ruby interpreter
-    # instance does.
-    class MemoryStore
-      GLOBAL_HASH_TABLE = {} #:nodoc:
-
-      # Create a new MemoryStore instance.
-      #
-      # +session+ is the session this instance is associated with.
-      # +option+ is a list of initialisation options.  None are
-      # currently recognised.
-      def initialize(session, option=nil)
-        @session_id = session.session_id
-        unless GLOBAL_HASH_TABLE.key?(@session_id)
-          unless session.new_session
-            raise CGI::Session::NoSession, "uninitialized session"
-          end
-          GLOBAL_HASH_TABLE[@session_id] = {}
-        end
-      end
-
-      # Restore session state.
-      #
-      # Returns session data as a hash.
-      def restore
-        GLOBAL_HASH_TABLE[@session_id]
-      end
-
-      # Update session state.
-      #
-      # A no-op.
-      def update
-        # don't need to update; hash is shared
-      end
-
-      # Close session storage.
-      #
-      # A no-op.
-      def close
-        # don't need to close
-      end
-
-      # Delete the session state.
-      def delete
-        GLOBAL_HASH_TABLE.delete(@session_id)
-      end
-    end
-
-    # Dummy session storage class.
-    #
-    # Implements session storage place holder.  No actual storage
-    # will be done.
-    class NullStore
-      # Create a new NullStore instance.
-      #
-      # +session+ is the session this instance is associated with.
-      # +option+ is a list of initialisation options.  None are
-      # currently recognised.
-      def initialize(session, option=nil)
-      end
-
-      # Restore (empty) session state.
-      def restore
-        {}
-      end
-
-      # Update session state.
-      #
-      # A no-op.
-      def update
-      end
-
-      # Close session storage.
-      #
-      # A no-op.
-      def close
-      end
-
-      # Delete the session state.
-      #
-      # A no-op.
-      def delete
-      end
-    end
-  end
-end
diff --git a/lib/cgi/session/pstore.rb b/lib/cgi/session/pstore.rb
deleted file mode 100644
index a63d7d3984..0000000000
--- a/lib/cgi/session/pstore.rb
+++ /dev/null
@@ -1,111 +0,0 @@
-#
-# cgi/session/pstore.rb - persistent storage of marshalled session data
-#
-# Documentation: William Webber (william@williamwebber.com)
-#
-# == Overview
-#
-# This file provides the CGI::Session::PStore class, which builds
-# persistent of session data on top of the pstore library.  See
-# cgi/session.rb for more details on session storage managers.
-
-require 'cgi/session'
-require 'pstore'
-
-class CGI
-  class Session
-    # PStore-based session storage class.
-    #
-    # This builds upon the top-level PStore class provided by the
-    # library file pstore.rb.  Session data is marshalled and stored
-    # in a file.  File locking and transaction services are provided.
-    class PStore
-      # Create a new CGI::Session::PStore instance
-      #
-      # This constructor is used internally by CGI::Session.  The
-      # user does not generally need to call it directly.
-      #
-      # +session+ is the session for which this instance is being
-      # created.  The session id must only contain alphanumeric
-      # characters; automatically generated session ids observe
-      # this requirement.
-      #
-      # +option+ is a hash of options for the initializer.  The
-      # following options are recognised:
-      #
-      # tmpdir:: the directory to use for storing the PStore
-      #          file.  Defaults to Dir::tmpdir (generally "/tmp"
-      #          on Unix systems).
-      # prefix:: the prefix to add to the session id when generating
-      #          the filename for this session's PStore file.
-      #          Defaults to the empty string.
-      #
-      # This session's PStore file will be created if it does
-      # not exist, or opened if it does.
-      def initialize(session, option={})
-        dir = option['tmpdir'] || Dir::tmpdir
-        prefix = option['prefix'] || ''
-        id = session.session_id
-        require 'digest/md5'
-        md5 = Digest::MD5.hexdigest(id)[0,16]
-        path = dir+"/"+prefix+md5
-        path.untaint
-        if File::exist?(path)
-          @hash = nil
-        else
-          unless session.new_session
-            raise CGI::Session::NoSession, "uninitialized session"
-          end
-          @hash = {}
-        end
-        @p = ::PStore.new(path)
-        @p.transaction do |p|
-          File.chmod(0600, p.path)
-        end
-      end
-
-      # Restore session state from the session's PStore file.
-      #
-      # Returns the session state as a hash.
-      def restore
-        unless @hash
-          @p.transaction do
-            @hash = @p['hash'] || {}
-          end
-        end
-        @hash
-      end
-
-      # Save session state to the session's PStore file.
-      def update
-        @p.transaction do
-          @p['hash'] = @hash
-        end
-      end
-
-      # Update and close the session's PStore file.
-      def close
-        update
-      end
-
-      # Close and delete the session's PStore file.
-      def delete
-        path = @p.path
-        File::unlink path
-      end
-
-    end
-  end
-end
-
-if $0 == __FILE__
-  # :enddoc:
-  STDIN.reopen("/dev/null")
-  cgi = CGI.new
-  session = CGI::Session.new(cgi, 'database_manager' => CGI::Session::PStore)
-  session['key'] = {'k' => 'v'}
-  puts session['key'].class
-  fail unless Hash === session['key']
-  puts session['key'].inspect
-  fail unless session['key'].inspect == '{"k"=>"v"}'
-end
diff --git a/lib/cgi/util.rb b/lib/cgi/util.rb
index 2bb3b0da78..50a2e91665 100644
--- a/lib/cgi/util.rb
+++ b/lib/cgi/util.rb
@@ -1,194 +1,7 @@
-class CGI
-  @@accept_charset="UTF-8" unless defined?(@@accept_charset)
-  # URL-encode a string.
-  #   url_encoded_string = CGI::escape("'Stop!' said Fred")
-  #      # => "%27Stop%21%27+said+Fred"
-  def CGI::escape(string)
-    string.gsub(/([^ a-zA-Z0-9_.-]+)/) do
-      '%' + $1.unpack('H2' * $1.bytesize).join('%').upcase
-    end.tr(' ', '+')
-  end
+# frozen_string_literal: true
 
-  # URL-decode a string with encoding(optional).
-  #   string = CGI::unescape("%27Stop%21%27+said+Fred")
-  #      # => "'Stop!' said Fred"
-  def CGI::unescape(string,encoding=@@accept_charset)
-    str=string.tr('+', ' ').force_encoding(Encoding::ASCII_8BIT).gsub(/((?:%[0-9a-fA-F]{2})+)/) do
-      [$1.delete('%')].pack('H*')
-    end.force_encoding(encoding)
-    str.valid_encoding? ? str : str.force_encoding(string.encoding)
-  end
-
-  # The set of special characters and their escaped values
-  TABLE_FOR_ESCAPE_HTML__ = {
-    '&' => '&amp;',
-    '"' => '&quot;',
-    '<' => '&lt;',
-    '>' => '&gt;',
-  }
-
-  # Escape special characters in HTML, namely &\"<>
-  #   CGI::escapeHTML('Usage: foo "bar" <baz>')
-  #      # => "Usage: foo &quot;bar&quot; &lt;baz&gt;"
-  def CGI::escapeHTML(string)
-    string.gsub(/[&\"<>]/, TABLE_FOR_ESCAPE_HTML__)
-  end
-
-  # Unescape a string that has been HTML-escaped
-  #   CGI::unescapeHTML("Usage: foo &quot;bar&quot; &lt;baz&gt;")
-  #      # => "Usage: foo \"bar\" <baz>"
-  def CGI::unescapeHTML(string)
-    enc = string.encoding
-    if [Encoding::UTF_16BE, Encoding::UTF_16LE, Encoding::UTF_32BE, Encoding::UTF_32LE].include?(enc)
-      return string.gsub(Regexp.new('&(amp|quot|gt|lt|#[0-9]+|#x[0-9A-Fa-f]+);'.encode(enc))) do
-        case $1.encode("US-ASCII")
-        when 'amp'                 then '&'.encode(enc)
-        when 'quot'                then '"'.encode(enc)
-        when 'gt'                  then '>'.encode(enc)
-        when 'lt'                  then '<'.encode(enc)
-        when /\A#0*(\d+)\z/        then $1.to_i.chr(enc)
-        when /\A#x([0-9a-f]+)\z/i  then $1.hex.chr(enc)
-        end
-      end
-    end
-    asciicompat = Encoding.compatible?(string, "a")
-    string.gsub(/&(amp|quot|gt|lt|\#[0-9]+|\#x[0-9A-Fa-f]+);/) do
-      match = $1.dup
-      case match
-      when 'amp'                 then '&'
-      when 'quot'                then '"'
-      when 'gt'                  then '>'
-      when 'lt'                  then '<'
-      when /\A#0*(\d+)\z/
-        n = $1.to_i
-        if enc == Encoding::UTF_8 or
-          enc == Encoding::ISO_8859_1 && n < 256 or
-          asciicompat && n < 128
-          n.chr(enc)
-        else
-          "&##{$1};"
-        end
-      when /\A#x([0-9a-f]+)\z/i
-        n = $1.hex
-        if enc == Encoding::UTF_8 or
-          enc == Encoding::ISO_8859_1 && n < 256 or
-          asciicompat && n < 128
-          n.chr(enc)
-        else
-          "&#x#{$1};"
-        end
-      else
-        "&#{match};"
-      end
-    end
-  end
-
-  # Synonym for CGI::escapeHTML(str)
-  def CGI::escape_html(str)
-    escapeHTML(str)
-  end
-  
-  # Synonym for CGI::unescapeHTML(str)
-  def CGI::unescape_html(str)
-    unescapeHTML(str)
-  end
-
-  # Escape only the tags of certain HTML elements in +string+.
-  #
-  # Takes an element or elements or array of elements.  Each element
-  # is specified by the name of the element, without angle brackets.
-  # This matches both the start and the end tag of that element.
-  # The attribute list of the open tag will also be escaped (for
-  # instance, the double-quotes surrounding attribute values).
-  #
-  #   print CGI::escapeElement('<BR><A HREF="url"></A>', "A", "IMG")
-  #     # "<BR>&lt;A HREF=&quot;url&quot;&gt;&lt;/A&gt"
-  #
-  #   print CGI::escapeElement('<BR><A HREF="url"></A>', ["A", "IMG"])
-  #     # "<BR>&lt;A HREF=&quot;url&quot;&gt;&lt;/A&gt"
-  def CGI::escapeElement(string, *elements)
-    elements = elements[0] if elements[0].kind_of?(Array)
-    unless elements.empty?
-      string.gsub(/<\/?(?:#{elements.join("|")})(?!\w)(?:.|\n)*?>/i) do
-        CGI::escapeHTML($&)
-      end
-    else
-      string
-    end
-  end
-
-  # Undo escaping such as that done by CGI::escapeElement()
-  #
-  #   print CGI::unescapeElement(
-  #           CGI::escapeHTML('<BR><A HREF="url"></A>'), "A", "IMG")
-  #     # "&lt;BR&gt;<A HREF="url"></A>"
-  #
-  #   print CGI::unescapeElement(
-  #           CGI::escapeHTML('<BR><A HREF="url"></A>'), ["A", "IMG"])
-  #     # "&lt;BR&gt;<A HREF="url"></A>"
-  def CGI::unescapeElement(string, *elements)
-    elements = elements[0] if elements[0].kind_of?(Array)
-    unless elements.empty?
-      string.gsub(/&lt;\/?(?:#{elements.join("|")})(?!\w)(?:.|\n)*?&gt;/i) do
-        CGI::unescapeHTML($&)
-      end
-    else
-      string
-    end
-  end
-
-  # Synonym for CGI::escapeElement(str)
-  def CGI::escape_element(str)
-    escapeElement(str)
-  end
-  
-  # Synonym for CGI::unescapeElement(str)
-  def CGI::unescape_element(str)
-    unescapeElement(str)
-  end
-
-  # Abbreviated day-of-week names specified by RFC 822
-  RFC822_DAYS = %w[ Sun Mon Tue Wed Thu Fri Sat ]
-
-  # Abbreviated month names specified by RFC 822
-  RFC822_MONTHS = %w[ Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec ]
-
-  # Format a +Time+ object as a String using the format specified by RFC 1123.
-  #
-  #   CGI::rfc1123_date(Time.now)
-  #     # Sat, 01 Jan 2000 00:00:00 GMT
-  def CGI::rfc1123_date(time)
-    t = time.clone.gmtime
-    return format("%s, %.2d %s %.4d %.2d:%.2d:%.2d GMT",
-                RFC822_DAYS[t.wday], t.day, RFC822_MONTHS[t.month-1], t.year,
-                t.hour, t.min, t.sec)
-  end
-
-  # Prettify (indent) an HTML string.
-  #
-  # +string+ is the HTML string to indent.  +shift+ is the indentation
-  # unit to use; it defaults to two spaces.
-  #
-  #   print CGI::pretty("<HTML><BODY></BODY></HTML>")
-  #     # <HTML>
-  #     #   <BODY>
-  #     #   </BODY>
-  #     # </HTML>
-  #
-  #   print CGI::pretty("<HTML><BODY></BODY></HTML>", "\t")
-  #     # <HTML>
-  #     #         <BODY>
-  #     #         </BODY>
-  #     # </HTML>
-  #
-  def CGI::pretty(string, shift = "  ")
-    lines = string.gsub(/(?!\A)<.*?>/m, "\n\\0").gsub(/<.*?>(?!\n)/m, "\\0\n")
-    end_pos = 0
-    while end_pos = lines.index(/^<\/(\w+)/, end_pos)
-      element = $1.dup
-      start_pos = lines.rindex(/^\s*<#{element}/i, end_pos)
-      lines[start_pos ... end_pos] = "__" + lines[start_pos ... end_pos].gsub(/\n(?!\z)/, "\n" + shift) + "__"
-    end
-    lines.gsub(/^((?:#{Regexp::quote(shift)})*)__(?=<\/?\w)/, '\1')
-  end
-end
+require "cgi/escape"
+warn <<-WARNING, uplevel: Gem::BUNDLED_GEMS.uplevel if $VERBOSE
+CGI::Util is removed from Ruby 4.0. Please use cgi/escape instead for CGI.escape and CGI.unescape features.
+If you are using CGI.parse, please install and use the cgi gem instead.
+WARNING
diff --git a/lib/cmath.rb b/lib/cmath.rb
deleted file mode 100644
index d613a3f6f9..0000000000
--- a/lib/cmath.rb
+++ /dev/null
@@ -1,402 +0,0 @@
-##
-# = CMath
-#
-# CMath is a library that provides trigonometric and transcendental
-# functions for complex numbers.
-#
-# == Usage
-#
-# To start using this library, simply:
-#
-#   require "cmath"
-#
-# Square root of a negative number is a complex number.
-#
-#   CMath.sqrt(-9)  #=> 0+3.0i
-#
-
-module CMath
-
-  include Math
-
-  alias exp! exp
-  alias log! log
-  alias log2! log2
-  alias log10! log10
-  alias sqrt! sqrt
-  alias cbrt! cbrt
-
-  alias sin! sin
-  alias cos! cos
-  alias tan! tan
-
-  alias sinh! sinh
-  alias cosh! cosh
-  alias tanh! tanh
-
-  alias asin! asin
-  alias acos! acos
-  alias atan! atan
-  alias atan2! atan2
-
-  alias asinh! asinh
-  alias acosh! acosh
-  alias atanh! atanh
-
-  ##
-  # Math::E raised to the +z+ power
-  #
-  #   exp(Complex(0,0))      #=> 1.0+0.0i
-  #   exp(Complex(0,PI))     #=> -1.0+1.2246467991473532e-16i
-  #   exp(Complex(0,PI/2.0)) #=> 6.123233995736766e-17+1.0i
-  def exp(z)
-    begin
-      if z.real?
-	exp!(z)
-      else
-	ere = exp!(z.real)
-	Complex(ere * cos!(z.imag),
-		ere * sin!(z.imag))
-      end
-    rescue NoMethodError
-      handle_no_method_error
-    end
-  end
-
-  ##
-  # Returns the natural logarithm of Complex.  If a second argument is given,
-  # it will be the base of logarithm.
-  #
-  #   log(Complex(0,0)) #=> -Infinity+0.0i
-  def log(*args)
-    begin
-      z, b = args
-      unless b.nil? || b.kind_of?(Numeric)
-	raise TypeError,  "Numeric Number required"
-      end
-      if z.real? and z >= 0 and (b.nil? or b >= 0)
-	log!(*args)
-      else
-	a = Complex(log!(z.abs), z.arg)
-	if b
-	  a /= log(b)
-        end
-        a
-      end
-    rescue NoMethodError
-      handle_no_method_error
-    end
-  end
-
-  ##
-  # returns the base 2 logarithm of +z+
-  def log2(z)
-    begin
-      if z.real? and z >= 0
-	log2!(z)
-      else
-	log(z) / log!(2)
-      end
-    rescue NoMethodError
-      handle_no_method_error
-    end
-  end
-
-  ##
-  # returns the base 10 logarithm of +z+
-  def log10(z)
-    begin
-      if z.real? and z >= 0
-	log10!(z)
-      else
-	log(z) / log!(10)
-      end
-    rescue NoMethodError
-      handle_no_method_error
-    end
-  end
-
-  ##
-  # Returns the non-negative square root of Complex.
-  #   sqrt(-1)            #=> 0+1.0i
-  #   sqrt(Complex(-1,0)) #=> 0.0+1.0i
-  #   sqrt(Complex(0,8))  #=> 2.0+2.0i
-  def sqrt(z)
-    begin
-      if z.real?
-	if z < 0
-	  Complex(0, sqrt!(-z))
-	else
-	  sqrt!(z)
-	end
-      else
-	if z.imag < 0 ||
-	    (z.imag == 0 && z.imag.to_s[0] == '-')
-	  sqrt(z.conjugate).conjugate
-	else
-	  r = z.abs
-	  x = z.real
-	  Complex(sqrt!((r + x) / 2.0), sqrt!((r - x) / 2.0))
-	end
-      end
-    rescue NoMethodError
-      handle_no_method_error
-    end
-  end
-
-  ##
-  # returns the principal value of the cube root of +z+
-  def cbrt(z)
-    z ** (1.0/3)
-  end
-
-  ##
-  # returns the sine of +z+, where +z+ is given in radians
-  def sin(z)
-    begin
-      if z.real?
-	sin!(z)
-      else
-	Complex(sin!(z.real) * cosh!(z.imag),
-		cos!(z.real) * sinh!(z.imag))
-      end
-    rescue NoMethodError
-      handle_no_method_error
-    end
-  end
-
-  ##
-  # returns the cosine of +z+, where +z+ is given in radians
-  def cos(z)
-    begin
-      if z.real?
-	cos!(z)
-      else
-	Complex(cos!(z.real) * cosh!(z.imag),
-		-sin!(z.real) * sinh!(z.imag))
-      end
-    rescue NoMethodError
-      handle_no_method_error
-    end
-  end
-
-  ##
-  # returns the tangent of +z+, where +z+ is given in radians
-  def tan(z)
-    begin
-      if z.real?
-	tan!(z)
-      else
-	sin(z) / cos(z)
-      end
-    rescue NoMethodError
-      handle_no_method_error
-    end
-  end
-
-  ##
-  # returns the hyperbolic sine of +z+, where +z+ is given in radians
-  def sinh(z)
-    begin
-      if z.real?
-	sinh!(z)
-      else
-	Complex(sinh!(z.real) * cos!(z.imag),
-		cosh!(z.real) * sin!(z.imag))
-      end
-    rescue NoMethodError
-      handle_no_method_error
-    end
-  end
-
-  ##
-  # returns the hyperbolic cosine of +z+, where +z+ is given in radians
-  def cosh(z)
-    begin
-      if z.real?
-	cosh!(z)
-      else
-	Complex(cosh!(z.real) * cos!(z.imag),
-		sinh!(z.real) * sin!(z.imag))
-      end
-    rescue NoMethodError
-      handle_no_method_error
-    end
-  end
-
-  ##
-  # returns the hyperbolic tangent of +z+, where +z+ is given in radians
-  def tanh(z)
-    begin
-      if z.real?
-	tanh!(z)
-      else
-	sinh(z) / cosh(z)
-      end
-    rescue NoMethodError
-      handle_no_method_error
-    end
-  end
-
-  ##
-  # returns the arc sine of +z+
-  def asin(z)
-    begin
-      if z.real? and z >= -1 and z <= 1
-	asin!(z)
-      else
-	(-1.0).i * log(1.0.i * z + sqrt(1.0 - z * z))
-      end
-    rescue NoMethodError
-      handle_no_method_error
-    end
-  end
-
-  ##
-  # returns the arc cosine of +z+
-  def acos(z)
-    begin
-      if z.real? and z >= -1 and z <= 1
-	acos!(z)
-      else
-	(-1.0).i * log(z + 1.0.i * sqrt(1.0 - z * z))
-      end
-    rescue NoMethodError
-      handle_no_method_error
-    end
-  end
-
-  ##
-  # returns the arc tangent of +z+
-  def atan(z)
-    begin
-      if z.real?
-	atan!(z)
-      else
-	1.0.i * log((1.0.i + z) / (1.0.i - z)) / 2.0
-      end
-    rescue NoMethodError
-      handle_no_method_error
-    end
-  end
-
-  ##
-  # returns the arc tangent of +y+ divided by +x+ using the signs of +y+ and
-  # +x+ to determine the quadrant
-  def atan2(y,x)
-    begin
-      if y.real? and x.real?
-	atan2!(y,x)
-      else
-	(-1.0).i * log((x + 1.0.i * y) / sqrt(x * x + y * y))
-      end
-    rescue NoMethodError
-      handle_no_method_error
-    end
-  end
-
-  ##
-  # returns the inverse hyperbolic sine of +z+
-  def asinh(z)
-    begin
-      if z.real?
-	asinh!(z)
-      else
-	log(z + sqrt(1.0 + z * z))
-      end
-    rescue NoMethodError
-      handle_no_method_error
-    end
-  end
-
-  ##
-  # returns the inverse hyperbolic cosine of +z+
-  def acosh(z)
-    begin
-      if z.real? and z >= 1
-	acosh!(z)
-      else
-	log(z + sqrt(z * z - 1.0))
-      end
-    rescue NoMethodError
-      handle_no_method_error
-    end
-  end
-
-  ##
-  # returns the inverse hyperbolic tangent of +z+
-  def atanh(z)
-    begin
-      if z.real? and z >= -1 and z <= 1
-	atanh!(z)
-      else
-	log((1.0 + z) / (1.0 - z)) / 2.0
-      end
-    rescue NoMethodError
-      handle_no_method_error
-    end
-  end
-
-  module_function :exp!
-  module_function :exp
-  module_function :log!
-  module_function :log
-  module_function :log2!
-  module_function :log2
-  module_function :log10!
-  module_function :log10
-  module_function :sqrt!
-  module_function :sqrt
-  module_function :cbrt!
-  module_function :cbrt
-
-  module_function :sin!
-  module_function :sin
-  module_function :cos!
-  module_function :cos
-  module_function :tan!
-  module_function :tan
-
-  module_function :sinh!
-  module_function :sinh
-  module_function :cosh!
-  module_function :cosh
-  module_function :tanh!
-  module_function :tanh
-
-  module_function :asin!
-  module_function :asin
-  module_function :acos!
-  module_function :acos
-  module_function :atan!
-  module_function :atan
-  module_function :atan2!
-  module_function :atan2
-
-  module_function :asinh!
-  module_function :asinh
-  module_function :acosh!
-  module_function :acosh
-  module_function :atanh!
-  module_function :atanh
-
-  module_function :frexp
-  module_function :ldexp
-  module_function :hypot
-  module_function :erf
-  module_function :erfc
-  module_function :gamma
-  module_function :lgamma
-
-  private
-  def handle_no_method_error # :nodoc:
-    if $!.name == :real?
-      raise TypeError, "Numeric Number required"
-    else
-      raise
-    end
-  end
-  module_function :handle_no_method_error
-
-end
-
diff --git a/lib/complex.rb b/lib/complex.rb
deleted file mode 100644
index 9c57ecdf7a..0000000000
--- a/lib/complex.rb
+++ /dev/null
@@ -1,28 +0,0 @@
-# :enddoc:
-
-warn('lib/complex.rb is deprecated') if $VERBOSE
-
-require 'cmath'
-
-unless defined?(Math.exp!)
-  Object.instance_eval{remove_const :Math}
-  Math = CMath
-end
-
-def Complex.generic? (other)
-  other.kind_of?(Integer) ||
-  other.kind_of?(Float)   ||
-  other.kind_of?(Rational)
-end
-
-class Complex
-
-  alias image imag
-
-end
-
-class Numeric
-
-  def im() Complex(0, self) end
-
-end
diff --git a/lib/csv.rb b/lib/csv.rb
deleted file mode 100644
index 13f86ec318..0000000000
--- a/lib/csv.rb
+++ /dev/null
@@ -1,2356 +0,0 @@
-# encoding: US-ASCII
-# = csv.rb -- CSV Reading and Writing
-#
-#  Created by James Edward Gray II on 2005-10-31.
-#  Copyright 2005 James Edward Gray II. You can redistribute or modify this code
-#  under the terms of Ruby's license.
-#
-# See CSV for documentation.
-#
-# == Description
-#
-# Welcome to the new and improved CSV.
-#
-# This version of the CSV library began its life as FasterCSV.  FasterCSV was
-# intended as a replacement to Ruby's then standard CSV library.  It was
-# designed to address concerns users of that library had and it had three
-# primary goals:
-#
-# 1.  Be significantly faster than CSV while remaining a pure Ruby library.
-# 2.  Use a smaller and easier to maintain code base.  (FasterCSV eventually
-#     grew larger, was also but considerably richer in features.  The parsing
-#     core remains quite small.)
-# 3.  Improve on the CSV interface.
-#
-# Obviously, the last one is subjective.  I did try to defer to the original
-# interface whenever I didn't have a compelling reason to change it though, so
-# hopefully this won't be too radically different.
-#
-# We must have met our goals because FasterCSV was renamed to CSV and replaced
-# the original library as of Ruby 1.9. If you are migrating code from 1.8 or
-# earlier, you may have to change your code to comply with the new interface.
-#
-# == What's Different From the Old CSV?
-#
-# I'm sure I'll miss something, but I'll try to mention most of the major
-# differences I am aware of, to help others quickly get up to speed:
-#
-# === CSV Parsing
-#
-# * This parser is m17n aware.  See CSV for full details.
-# * This library has a stricter parser and will throw MalformedCSVErrors on
-#   problematic data.
-# * This library has a less liberal idea of a line ending than CSV.  What you
-#   set as the <tt>:row_sep</tt> is law.  It can auto-detect your line endings
-#   though.
-# * The old library returned empty lines as <tt>[nil]</tt>.  This library calls
-#   them <tt>[]</tt>.
-# * This library has a much faster parser.
-#
-# === Interface
-#
-# * CSV now uses Hash-style parameters to set options.
-# * CSV no longer has generate_row() or parse_row().
-# * The old CSV's Reader and Writer classes have been dropped.
-# * CSV::open() is now more like Ruby's open().
-# * CSV objects now support most standard IO methods.
-# * CSV now has a new() method used to wrap objects like String and IO for
-#   reading and writing.
-# * CSV::generate() is different from the old method.
-# * CSV no longer supports partial reads.  It works line-by-line.
-# * CSV no longer allows the instance methods to override the separators for
-#   performance reasons.  They must be set in the constructor.
-#
-# If you use this library and find yourself missing any functionality I have
-# trimmed, please {let me know}[mailto:james@grayproductions.net].
-#
-# == Documentation
-#
-# See CSV for documentation.
-#
-# == What is CSV, really?
-#
-# CSV maintains a pretty strict definition of CSV taken directly from
-# {the RFC}[http://www.ietf.org/rfc/rfc4180.txt].  I relax the rules in only one
-# place and that is to make using this library easier.  CSV will parse all valid
-# CSV.
-#
-# What you don't want to do is feed CSV invalid data.  Because of the way the
-# CSV format works, it's common for a parser to need to read until the end of
-# the file to be sure a field is invalid.  This eats a lot of time and memory.
-#
-# Luckily, when working with invalid CSV, Ruby's built-in methods will almost
-# always be superior in every way.  For example, parsing non-quoted fields is as
-# easy as:
-#
-#   data.split(",")
-#
-# == Questions and/or Comments
-#
-# Feel free to email {James Edward Gray II}[mailto:james@grayproductions.net]
-# with any questions.
-
-require "forwardable"
-require "English"
-require "date"
-require "stringio"
-
-#
-# This class provides a complete interface to CSV files and data.  It offers
-# tools to enable you to read and write to and from Strings or IO objects, as
-# needed.
-#
-# == Reading
-#
-# === From a File
-#
-# ==== A Line at a Time
-#
-#   CSV.foreach("path/to/file.csv") do |row|
-#     # use row here...
-#   end
-#
-# ==== All at Once
-#
-#   arr_of_arrs = CSV.read("path/to/file.csv")
-#
-# === From a String
-#
-# ==== A Line at a Time
-#
-#   CSV.parse("CSV,data,String") do |row|
-#     # use row here...
-#   end
-#
-# ==== All at Once
-#
-#   arr_of_arrs = CSV.parse("CSV,data,String")
-#
-# == Writing
-#
-# === To a File
-#
-#   CSV.open("path/to/file.csv", "wb") do |csv|
-#     csv << ["row", "of", "CSV", "data"]
-#     csv << ["another", "row"]
-#     # ...
-#   end
-#
-# === To a String
-#
-#   csv_string = CSV.generate do |csv|
-#     csv << ["row", "of", "CSV", "data"]
-#     csv << ["another", "row"]
-#     # ...
-#   end
-#
-# == Convert a Single Line
-#
-#   csv_string = ["CSV", "data"].to_csv   # to CSV
-#   csv_array  = "CSV,String".parse_csv   # from CSV
-#
-# == Shortcut Interface
-#
-#   CSV             { |csv_out| csv_out << %w{my data here} }  # to $stdout
-#   CSV(csv = "")   { |csv_str| csv_str << %w{my data here} }  # to a String
-#   CSV($stderr)    { |csv_err| csv_err << %w{my data here} }  # to $stderr
-#   CSV($stdin)     { |csv_in|  csv_in.each { |row| p row } }  # from $stdin
-#
-# == Advanced Usage
-#
-# === Wrap an IO Object
-#
-#   csv = CSV.new(io, options)
-#   # ... read (with gets() or each()) from and write (with <<) to csv here ...
-#
-# == CSV and Character Encodings (M17n or Multilingualization)
-#
-# This new CSV parser is m17n savvy.  The parser works in the Encoding of the IO
-# or String object being read from or written to.  Your data is never transcoded
-# (unless you ask Ruby to transcode it for you) and will literally be parsed in
-# the Encoding it is in.  Thus CSV will return Arrays or Rows of Strings in the
-# Encoding of your data.  This is accomplished by transcoding the parser itself
-# into your Encoding.
-#
-# Some transcoding must take place, of course, to accomplish this multiencoding
-# support.  For example, <tt>:col_sep</tt>, <tt>:row_sep</tt>, and
-# <tt>:quote_char</tt> must be transcoded to match your data.  Hopefully this
-# makes the entire process feel transparent, since CSV's defaults should just
-# magically work for you data.  However, you can set these values manually in
-# the target Encoding to avoid the translation.
-#
-# It's also important to note that while all of CSV's core parser is now
-# Encoding agnostic, some features are not.  For example, the built-in
-# converters will try to transcode data to UTF-8 before making conversions.
-# Again, you can provide custom converters that are aware of your Encodings to
-# avoid this translation.  It's just too hard for me to support native
-# conversions in all of Ruby's Encodings.
-#
-# Anyway, the practical side of this is simple:  make sure IO and String objects
-# passed into CSV have the proper Encoding set and everything should just work.
-# CSV methods that allow you to open IO objects (CSV::foreach(), CSV::open(),
-# CSV::read(), and CSV::readlines()) do allow you to specify the Encoding.
-#
-# One minor exception comes when generating CSV into a String with an Encoding
-# that is not ASCII compatible.  There's no existing data for CSV to use to
-# prepare itself and thus you will probably need to manually specify the desired
-# Encoding for most of those cases.  It will try to guess using the fields in a
-# row of output though, when using CSV::generate_line() or Array#to_csv().
-#
-# I try to point out any other Encoding issues in the documentation of methods
-# as they come up.
-#
-# This has been tested to the best of my ability with all non-"dummy" Encodings
-# Ruby ships with.  However, it is brave new code and may have some bugs.
-# Please feel free to {report}[mailto:james@grayproductions.net] any issues you
-# find with it.
-#
-class CSV
-  # The version of the installed library.
-  VERSION = "2.4.8".freeze
-
-  #
-  # A CSV::Row is part Array and part Hash.  It retains an order for the fields
-  # and allows duplicates just as an Array would, but also allows you to access
-  # fields by name just as you could if they were in a Hash.
-  #
-  # All rows returned by CSV will be constructed from this class, if header row
-  # processing is activated.
-  #
-  class Row
-    #
-    # Construct a new CSV::Row from +headers+ and +fields+, which are expected
-    # to be Arrays.  If one Array is shorter than the other, it will be padded
-    # with +nil+ objects.
-    #
-    # The optional +header_row+ parameter can be set to +true+ to indicate, via
-    # CSV::Row.header_row?() and CSV::Row.field_row?(), that this is a header
-    # row.  Otherwise, the row is assumes to be a field row.
-    #
-    # A CSV::Row object supports the following Array methods through delegation:
-    #
-    # * empty?()
-    # * length()
-    # * size()
-    #
-    def initialize(headers, fields, header_row = false)
-      @header_row = header_row
-
-      # handle extra headers or fields
-      @row = if headers.size > fields.size
-        headers.zip(fields)
-      else
-        fields.zip(headers).map { |pair| pair.reverse }
-      end
-    end
-
-    # Internal data format used to compare equality.
-    attr_reader :row
-    protected   :row
-
-    ### Array Delegation ###
-
-    extend Forwardable
-    def_delegators :@row, :empty?, :length, :size
-
-    # Returns +true+ if this is a header row.
-    def header_row?
-      @header_row
-    end
-
-    # Returns +true+ if this is a field row.
-    def field_row?
-      not header_row?
-    end
-
-    # Returns the headers of this row.
-    def headers
-      @row.map { |pair| pair.first }
-    end
-
-    #
-    # :call-seq:
-    #   field( header )
-    #   field( header, offset )
-    #   field( index )
-    #
-    # This method will fetch the field value by +header+ or +index+.  If a field
-    # is not found, +nil+ is returned.
-    #
-    # When provided, +offset+ ensures that a header match occurrs on or later
-    # than the +offset+ index.  You can use this to find duplicate headers,
-    # without resorting to hard-coding exact indices.
-    #
-    def field(header_or_index, minimum_index = 0)
-      # locate the pair
-      finder = header_or_index.is_a?(Integer) ? :[] : :assoc
-      pair   = @row[minimum_index..-1].send(finder, header_or_index)
-
-      # return the field if we have a pair
-      pair.nil? ? nil : pair.last
-    end
-    alias_method :[], :field
-
-    #
-    # :call-seq:
-    #   []=( header, value )
-    #   []=( header, offset, value )
-    #   []=( index, value )
-    #
-    # Looks up the field by the semantics described in CSV::Row.field() and
-    # assigns the +value+.
-    #
-    # Assigning past the end of the row with an index will set all pairs between
-    # to <tt>[nil, nil]</tt>.  Assigning to an unused header appends the new
-    # pair.
-    #
-    def []=(*args)
-      value = args.pop
-
-      if args.first.is_a? Integer
-        if @row[args.first].nil?  # extending past the end with index
-          @row[args.first] = [nil, value]
-          @row.map! { |pair| pair.nil? ? [nil, nil] : pair }
-        else                      # normal index assignment
-          @row[args.first][1] = value
-        end
-      else
-        index = index(*args)
-        if index.nil?             # appending a field
-          self << [args.first, value]
-        else                      # normal header assignment
-          @row[index][1] = value
-        end
-      end
-    end
-
-    #
-    # :call-seq:
-    #   <<( field )
-    #   <<( header_and_field_array )
-    #   <<( header_and_field_hash )
-    #
-    # If a two-element Array is provided, it is assumed to be a header and field
-    # and the pair is appended.  A Hash works the same way with the key being
-    # the header and the value being the field.  Anything else is assumed to be
-    # a lone field which is appended with a +nil+ header.
-    #
-    # This method returns the row for chaining.
-    #
-    def <<(arg)
-      if arg.is_a?(Array) and arg.size == 2  # appending a header and name
-        @row << arg
-      elsif arg.is_a?(Hash)                  # append header and name pairs
-        arg.each { |pair| @row << pair }
-      else                                   # append field value
-        @row << [nil, arg]
-      end
-
-      self  # for chaining
-    end
-
-    #
-    # A shortcut for appending multiple fields.  Equivalent to:
-    #
-    #   args.each { |arg| csv_row << arg }
-    #
-    # This method returns the row for chaining.
-    #
-    def push(*args)
-      args.each { |arg| self << arg }
-
-      self  # for chaining
-    end
-
-    #
-    # :call-seq:
-    #   delete( header )
-    #   delete( header, offset )
-    #   delete( index )
-    #
-    # Used to remove a pair from the row by +header+ or +index+.  The pair is
-    # located as described in CSV::Row.field().  The deleted pair is returned,
-    # or +nil+ if a pair could not be found.
-    #
-    def delete(header_or_index, minimum_index = 0)
-      if header_or_index.is_a? Integer                 # by index
-        @row.delete_at(header_or_index)
-      elsif i = index(header_or_index, minimum_index)  # by header
-        @row.delete_at(i)
-      else
-        [ ]
-      end
-    end
-
-    #
-    # The provided +block+ is passed a header and field for each pair in the row
-    # and expected to return +true+ or +false+, depending on whether the pair
-    # should be deleted.
-    #
-    # This method returns the row for chaining.
-    #
-    def delete_if(&block)
-      @row.delete_if(&block)
-
-      self  # for chaining
-    end
-
-    #
-    # This method accepts any number of arguments which can be headers, indices,
-    # Ranges of either, or two-element Arrays containing a header and offset.
-    # Each argument will be replaced with a field lookup as described in
-    # CSV::Row.field().
-    #
-    # If called with no arguments, all fields are returned.
-    #
-    def fields(*headers_and_or_indices)
-      if headers_and_or_indices.empty?  # return all fields--no arguments
-        @row.map { |pair| pair.last }
-      else                              # or work like values_at()
-        headers_and_or_indices.inject(Array.new) do |all, h_or_i|
-          all + if h_or_i.is_a? Range
-            index_begin = h_or_i.begin.is_a?(Integer) ? h_or_i.begin :
-                                                        index(h_or_i.begin)
-            index_end   = h_or_i.end.is_a?(Integer)   ? h_or_i.end :
-                                                        index(h_or_i.end)
-            new_range   = h_or_i.exclude_end? ? (index_begin...index_end) :
-                                                (index_begin..index_end)
-            fields.values_at(new_range)
-          else
-            [field(*Array(h_or_i))]
-          end
-        end
-      end
-    end
-    alias_method :values_at, :fields
-
-    #
-    # :call-seq:
-    #   index( header )
-    #   index( header, offset )
-    #
-    # This method will return the index of a field with the provided +header+.
-    # The +offset+ can be used to locate duplicate header names, as described in
-    # CSV::Row.field().
-    #
-    def index(header, minimum_index = 0)
-      # find the pair
-      index = headers[minimum_index..-1].index(header)
-      # return the index at the right offset, if we found one
-      index.nil? ? nil : index + minimum_index
-    end
-
-    # Returns +true+ if +name+ is a header for this row, and +false+ otherwise.
-    def header?(name)
-      headers.include? name
-    end
-    alias_method :include?, :header?
-
-    #
-    # Returns +true+ if +data+ matches a field in this row, and +false+
-    # otherwise.
-    #
-    def field?(data)
-      fields.include? data
-    end
-
-    include Enumerable
-
-    #
-    # Yields each pair of the row as header and field tuples (much like
-    # iterating over a Hash).
-    #
-    # Support for Enumerable.
-    #
-    # This method returns the row for chaining.
-    #
-    def each(&block)
-      @row.each(&block)
-
-      self  # for chaining
-    end
-
-    #
-    # Returns +true+ if this row contains the same headers and fields in the
-    # same order as +other+.
-    #
-    def ==(other)
-      @row == other.row
-    end
-
-    #
-    # Collapses the row into a simple Hash.  Be warning that this discards field
-    # order and clobbers duplicate fields.
-    #
-    def to_hash
-      # flatten just one level of the internal Array
-      Hash[*@row.inject(Array.new) { |ary, pair| ary.push(*pair) }]
-    end
-
-    #
-    # Returns the row as a CSV String.  Headers are not used.  Equivalent to:
-    #
-    #   csv_row.fields.to_csv( options )
-    #
-    def to_csv(options = Hash.new)
-      fields.to_csv(options)
-    end
-    alias_method :to_s, :to_csv
-
-    # A summary of fields, by header, in an ASCII compatible String.
-    def inspect
-      str = ["#<", self.class.to_s]
-      each do |header, field|
-        str << " " << (header.is_a?(Symbol) ? header.to_s : header.inspect) <<
-               ":" << field.inspect
-      end
-      str << ">"
-      begin
-        str.join('')
-      rescue  # any encoding error
-        str.map do |s|
-          e = Encoding::Converter.asciicompat_encoding(s.encoding)
-          e ? s.encode(e) : s.force_encoding("ASCII-8BIT")
-        end.join('')
-      end
-    end
-  end
-
-  #
-  # A CSV::Table is a two-dimensional data structure for representing CSV
-  # documents.  Tables allow you to work with the data by row or column,
-  # manipulate the data, and even convert the results back to CSV, if needed.
-  #
-  # All tables returned by CSV will be constructed from this class, if header
-  # row processing is activated.
-  #
-  class Table
-    #
-    # Construct a new CSV::Table from +array_of_rows+, which are expected
-    # to be CSV::Row objects.  All rows are assumed to have the same headers.
-    #
-    # A CSV::Table object supports the following Array methods through
-    # delegation:
-    #
-    # * empty?()
-    # * length()
-    # * size()
-    #
-    def initialize(array_of_rows)
-      @table = array_of_rows
-      @mode  = :col_or_row
-    end
-
-    # The current access mode for indexing and iteration.
-    attr_reader :mode
-
-    # Internal data format used to compare equality.
-    attr_reader :table
-    protected   :table
-
-    ### Array Delegation ###
-
-    extend Forwardable
-    def_delegators :@table, :empty?, :length, :size
-
-    #
-    # Returns a duplicate table object, in column mode.  This is handy for
-    # chaining in a single call without changing the table mode, but be aware
-    # that this method can consume a fair amount of memory for bigger data sets.
-    #
-    # This method returns the duplicate table for chaining.  Don't chain
-    # destructive methods (like []=()) this way though, since you are working
-    # with a duplicate.
-    #
-    def by_col
-      self.class.new(@table.dup).by_col!
-    end
-
-    #
-    # Switches the mode of this table to column mode.  All calls to indexing and
-    # iteration methods will work with columns until the mode is changed again.
-    #
-    # This method returns the table and is safe to chain.
-    #
-    def by_col!
-      @mode = :col
-
-      self
-    end
-
-    #
-    # Returns a duplicate table object, in mixed mode.  This is handy for
-    # chaining in a single call without changing the table mode, but be aware
-    # that this method can consume a fair amount of memory for bigger data sets.
-    #
-    # This method returns the duplicate table for chaining.  Don't chain
-    # destructive methods (like []=()) this way though, since you are working
-    # with a duplicate.
-    #
-    def by_col_or_row
-      self.class.new(@table.dup).by_col_or_row!
-    end
-
-    #
-    # Switches the mode of this table to mixed mode.  All calls to indexing and
-    # iteration methods will use the default intelligent indexing system until
-    # the mode is changed again.  In mixed mode an index is assumed to be a row
-    # reference while anything else is assumed to be column access by headers.
-    #
-    # This method returns the table and is safe to chain.
-    #
-    def by_col_or_row!
-      @mode = :col_or_row
-
-      self
-    end
-
-    #
-    # Returns a duplicate table object, in row mode.  This is handy for chaining
-    # in a single call without changing the table mode, but be aware that this
-    # method can consume a fair amount of memory for bigger data sets.
-    #
-    # This method returns the duplicate table for chaining.  Don't chain
-    # destructive methods (like []=()) this way though, since you are working
-    # with a duplicate.
-    #
-    def by_row
-      self.class.new(@table.dup).by_row!
-    end
-
-    #
-    # Switches the mode of this table to row mode.  All calls to indexing and
-    # iteration methods will work with rows until the mode is changed again.
-    #
-    # This method returns the table and is safe to chain.
-    #
-    def by_row!
-      @mode = :row
-
-      self
-    end
-
-    #
-    # Returns the headers for the first row of this table (assumed to match all
-    # other rows).  An empty Array is returned for empty tables.
-    #
-    def headers
-      if @table.empty?
-        Array.new
-      else
-        @table.first.headers
-      end
-    end
-
-    #
-    # In the default mixed mode, this method returns rows for index access and
-    # columns for header access.  You can force the index association by first
-    # calling by_col!() or by_row!().
-    #
-    # Columns are returned as an Array of values.  Altering that Array has no
-    # effect on the table.
-    #
-    def [](index_or_header)
-      if @mode == :row or  # by index
-         (@mode == :col_or_row and index_or_header.is_a? Integer)
-        @table[index_or_header]
-      else                 # by header
-        @table.map { |row| row[index_or_header] }
-      end
-    end
-
-    #
-    # In the default mixed mode, this method assigns rows for index access and
-    # columns for header access.  You can force the index association by first
-    # calling by_col!() or by_row!().
-    #
-    # Rows may be set to an Array of values (which will inherit the table's
-    # headers()) or a CSV::Row.
-    #
-    # Columns may be set to a single value, which is copied to each row of the
-    # column, or an Array of values.  Arrays of values are assigned to rows top
-    # to bottom in row major order.  Excess values are ignored and if the Array
-    # does not have a value for each row the extra rows will receive a +nil+.
-    #
-    # Assigning to an existing column or row clobbers the data.  Assigning to
-    # new columns creates them at the right end of the table.
-    #
-    def []=(index_or_header, value)
-      if @mode == :row or  # by index
-         (@mode == :col_or_row and index_or_header.is_a? Integer)
-        if value.is_a? Array
-          @table[index_or_header] = Row.new(headers, value)
-        else
-          @table[index_or_header] = value
-        end
-      else                 # set column
-        if value.is_a? Array  # multiple values
-          @table.each_with_index do |row, i|
-            if row.header_row?
-              row[index_or_header] = index_or_header
-            else
-              row[index_or_header] = value[i]
-            end
-          end
-        else                  # repeated value
-          @table.each do |row|
-            if row.header_row?
-              row[index_or_header] = index_or_header
-            else
-              row[index_or_header] = value
-            end
-          end
-        end
-      end
-    end
-
-    #
-    # The mixed mode default is to treat a list of indices as row access,
-    # returning the rows indicated.  Anything else is considered columnar
-    # access.  For columnar access, the return set has an Array for each row
-    # with the values indicated by the headers in each Array.  You can force
-    # column or row mode using by_col!() or by_row!().
-    #
-    # You cannot mix column and row access.
-    #
-    def values_at(*indices_or_headers)
-      if @mode == :row or  # by indices
-         ( @mode == :col_or_row and indices_or_headers.all? do |index|
-                                      index.is_a?(Integer)         or
-                                      ( index.is_a?(Range)         and
-                                        index.first.is_a?(Integer) and
-                                        index.last.is_a?(Integer) )
-                                    end )
-        @table.values_at(*indices_or_headers)
-      else                 # by headers
-        @table.map { |row| row.values_at(*indices_or_headers) }
-      end
-    end
-
-    #
-    # Adds a new row to the bottom end of this table.  You can provide an Array,
-    # which will be converted to a CSV::Row (inheriting the table's headers()),
-    # or a CSV::Row.
-    #
-    # This method returns the table for chaining.
-    #
-    def <<(row_or_array)
-      if row_or_array.is_a? Array  # append Array
-        @table << Row.new(headers, row_or_array)
-      else                         # append Row
-        @table << row_or_array
-      end
-
-      self  # for chaining
-    end
-
-    #
-    # A shortcut for appending multiple rows.  Equivalent to:
-    #
-    #   rows.each { |row| self << row }
-    #
-    # This method returns the table for chaining.
-    #
-    def push(*rows)
-      rows.each { |row| self << row }
-
-      self  # for chaining
-    end
-
-    #
-    # Removes and returns the indicated column or row.  In the default mixed
-    # mode indices refer to rows and everything else is assumed to be a column
-    # header.  Use by_col!() or by_row!() to force the lookup.
-    #
-    def delete(index_or_header)
-      if @mode == :row or  # by index
-         (@mode == :col_or_row and index_or_header.is_a? Integer)
-        @table.delete_at(index_or_header)
-      else                 # by header
-        @table.map { |row| row.delete(index_or_header).last }
-      end
-    end
-
-    #
-    # Removes any column or row for which the block returns +true+.  In the
-    # default mixed mode or row mode, iteration is the standard row major
-    # walking of rows.  In column mode, interation will +yield+ two element
-    # tuples containing the column name and an Array of values for that column.
-    #
-    # This method returns the table for chaining.
-    #
-    def delete_if(&block)
-      if @mode == :row or @mode == :col_or_row  # by index
-        @table.delete_if(&block)
-      else                                      # by header
-        to_delete = Array.new
-        headers.each_with_index do |header, i|
-          to_delete << header if block[[header, self[header]]]
-        end
-        to_delete.map { |header| delete(header) }
-      end
-
-      self  # for chaining
-    end
-
-    include Enumerable
-
-    #
-    # In the default mixed mode or row mode, iteration is the standard row major
-    # walking of rows.  In column mode, interation will +yield+ two element
-    # tuples containing the column name and an Array of values for that column.
-    #
-    # This method returns the table for chaining.
-    #
-    def each(&block)
-      if @mode == :col
-        headers.each { |header| block[[header, self[header]]] }
-      else
-        @table.each(&block)
-      end
-
-      self  # for chaining
-    end
-
-    # Returns +true+ if all rows of this table ==() +other+'s rows.
-    def ==(other)
-      @table == other.table
-    end
-
-    #
-    # Returns the table as an Array of Arrays.  Headers will be the first row,
-    # then all of the field rows will follow.
-    #
-    def to_a
-      @table.inject([headers]) do |array, row|
-        if row.header_row?
-          array
-        else
-          array + [row.fields]
-        end
-      end
-    end
-
-    #
-    # Returns the table as a complete CSV String.  Headers will be listed first,
-    # then all of the field rows.
-    #
-    # This method assumes you want the Table.headers(), unless you explicitly
-    # pass <tt>:write_headers => false</tt>.
-    #
-    def to_csv(options = Hash.new)
-      wh = options.fetch(:write_headers, true)
-      @table.inject(wh ? [headers.to_csv(options)] : [ ]) do |rows, row|
-        if row.header_row?
-          rows
-        else
-          rows + [row.fields.to_csv(options)]
-        end
-      end.join('')
-    end
-    alias_method :to_s, :to_csv
-
-    # Shows the mode and size of this table in a US-ASCII String.
-    def inspect
-      "#<#{self.class} mode:#{@mode} row_count:#{to_a.size}>".encode("US-ASCII")
-    end
-  end
-
-  # The error thrown when the parser encounters illegal CSV formatting.
-  class MalformedCSVError < RuntimeError; end
-
-  #
-  # A FieldInfo Struct contains details about a field's position in the data
-  # source it was read from.  CSV will pass this Struct to some blocks that make
-  # decisions based on field structure.  See CSV.convert_fields() for an
-  # example.
-  #
-  # <b><tt>index</tt></b>::  The zero-based index of the field in its row.
-  # <b><tt>line</tt></b>::   The line of the data source this row is from.
-  # <b><tt>header</tt></b>:: The header for the column, when available.
-  #
-  FieldInfo = Struct.new(:index, :line, :header)
-
-  # A Regexp used to find and convert some common Date formats.
-  DateMatcher     = / \A(?: (\w+,?\s+)?\w+\s+\d{1,2},?\s+\d{2,4} |
-                            \d{4}-\d{2}-\d{2} )\z /x
-  # A Regexp used to find and convert some common DateTime formats.
-  DateTimeMatcher =
-    / \A(?: (\w+,?\s+)?\w+\s+\d{1,2}\s+\d{1,2}:\d{1,2}:\d{1,2},?\s+\d{2,4} |
-            \d{4}-\d{2}-\d{2}\s\d{2}:\d{2}:\d{2} )\z /x
-
-  # The encoding used by all converters.
-  ConverterEncoding = Encoding.find("UTF-8")
-
-  #
-  # This Hash holds the built-in converters of CSV that can be accessed by name.
-  # You can select Converters with CSV.convert() or through the +options+ Hash
-  # passed to CSV::new().
-  #
-  # <b><tt>:integer</tt></b>::    Converts any field Integer() accepts.
-  # <b><tt>:float</tt></b>::      Converts any field Float() accepts.
-  # <b><tt>:numeric</tt></b>::    A combination of <tt>:integer</tt>
-  #                               and <tt>:float</tt>.
-  # <b><tt>:date</tt></b>::       Converts any field Date::parse() accepts.
-  # <b><tt>:date_time</tt></b>::  Converts any field DateTime::parse() accepts.
-  # <b><tt>:all</tt></b>::        All built-in converters.  A combination of
-  #                               <tt>:date_time</tt> and <tt>:numeric</tt>.
-  #
-  # All built-in converters transcode field data to UTF-8 before attempting a
-  # conversion.  If your data cannot be transcoded to UTF-8 the conversion will
-  # fail and the field will remain unchanged.
-  #
-  # This Hash is intentionally left unfrozen and users should feel free to add
-  # values to it that can be accessed by all CSV objects.
-  #
-  # To add a combo field, the value should be an Array of names.  Combo fields
-  # can be nested with other combo fields.
-  #
-  Converters  = { integer:   lambda { |f|
-                    Integer(f.encode(ConverterEncoding)) rescue f
-                  },
-                  float:     lambda { |f|
-                    Float(f.encode(ConverterEncoding)) rescue f
-                  },
-                  numeric:   [:integer, :float],
-                  date:      lambda { |f|
-                    begin
-                      e = f.encode(ConverterEncoding)
-                      e =~ DateMatcher ? Date.parse(e) : f
-                    rescue  # encoding conversion or date parse errors
-                      f
-                    end
-                  },
-                  date_time: lambda { |f|
-                    begin
-                      e = f.encode(ConverterEncoding)
-                      e =~ DateTimeMatcher ? DateTime.parse(e) : f
-                    rescue  # encoding conversion or date parse errors
-                      f
-                    end
-                  },
-                  all:       [:date_time, :numeric] }
-
-  #
-  # This Hash holds the built-in header converters of CSV that can be accessed
-  # by name.  You can select HeaderConverters with CSV.header_convert() or
-  # through the +options+ Hash passed to CSV::new().
-  #
-  # <b><tt>:downcase</tt></b>::  Calls downcase() on the header String.
-  # <b><tt>:symbol</tt></b>::    The header String is downcased, spaces are
-  #                              replaced with underscores, non-word characters
-  #                              are dropped, and finally to_sym() is called.
-  #
-  # All built-in header converters transcode header data to UTF-8 before
-  # attempting a conversion.  If your data cannot be transcoded to UTF-8 the
-  # conversion will fail and the header will remain unchanged.
-  #
-  # This Hash is intetionally left unfrozen and users should feel free to add
-  # values to it that can be accessed by all CSV objects.
-  #
-  # To add a combo field, the value should be an Array of names.  Combo fields
-  # can be nested with other combo fields.
-  #
-  HeaderConverters = {
-    downcase: lambda { |h| h.encode(ConverterEncoding).downcase },
-    symbol:   lambda { |h|
-      h.encode(ConverterEncoding).downcase.gsub(/\s+/, "_").
-                                           gsub(/\W+/, "").to_sym
-    }
-  }
-
-  #
-  # The options used when no overrides are given by calling code.  They are:
-  #
-  # <b><tt>:col_sep</tt></b>::            <tt>","</tt>
-  # <b><tt>:row_sep</tt></b>::            <tt>:auto</tt>
-  # <b><tt>:quote_char</tt></b>::         <tt>'"'</tt>
-  # <b><tt>:field_size_limit</tt></b>::   +nil+
-  # <b><tt>:converters</tt></b>::         +nil+
-  # <b><tt>:unconverted_fields</tt></b>:: +nil+
-  # <b><tt>:headers</tt></b>::            +false+
-  # <b><tt>:return_headers</tt></b>::     +false+
-  # <b><tt>:header_converters</tt></b>::  +nil+
-  # <b><tt>:skip_blanks</tt></b>::        +false+
-  # <b><tt>:force_quotes</tt></b>::       +false+
-  #
-  DEFAULT_OPTIONS = { col_sep:            ",",
-                      row_sep:            :auto,
-                      quote_char:         '"',
-                      field_size_limit:   nil,
-                      converters:         nil,
-                      unconverted_fields: nil,
-                      headers:            false,
-                      return_headers:     false,
-                      header_converters:  nil,
-                      skip_blanks:        false,
-                      force_quotes:       false }.freeze
-
-  #
-  # This method will return a CSV instance, just like CSV::new(), but the
-  # instance will be cached and returned for all future calls to this method for
-  # the same +data+ object (tested by Object#object_id()) with the same
-  # +options+.
-  #
-  # If a block is given, the instance is passed to the block and the return
-  # value becomes the return value of the block.
-  #
-  def self.instance(data = $stdout, options = Hash.new)
-    # create a _signature_ for this method call, data object and options
-    sig = [data.object_id] +
-          options.values_at(*DEFAULT_OPTIONS.keys.sort_by { |sym| sym.to_s })
-
-    # fetch or create the instance for this signature
-    @@instances ||= Hash.new
-    instance    =   (@@instances[sig] ||= new(data, options))
-
-    if block_given?
-      yield instance  # run block, if given, returning result
-    else
-      instance        # or return the instance
-    end
-  end
-
-  #
-  # This method allows you to serialize an Array of Ruby objects to a String or
-  # File of CSV data.  This is not as powerful as Marshal or YAML, but perhaps
-  # useful for spreadsheet and database interaction.
-  #
-  # Out of the box, this method is intended to work with simple data objects or
-  # Structs.  It will serialize a list of instance variables and/or
-  # Struct.members().
-  #
-  # If you need need more complicated serialization, you can control the process
-  # by adding methods to the class to be serialized.
-  #
-  # A class method csv_meta() is responsible for returning the first row of the
-  # document (as an Array).  This row is considered to be a Hash of the form
-  # key_1,value_1,key_2,value_2,...  CSV::load() expects to find a class key
-  # with a value of the stringified class name and CSV::dump() will create this,
-  # if you do not define this method.  This method is only called on the first
-  # object of the Array.
-  #
-  # The next method you can provide is an instance method called csv_headers().
-  # This method is expected to return the second line of the document (again as
-  # an Array), which is to be used to give each column a header.  By default,
-  # CSV::load() will set an instance variable if the field header starts with an
-  # @ character or call send() passing the header as the method name and
-  # the field value as an argument.  This method is only called on the first
-  # object of the Array.
-  #
-  # Finally, you can provide an instance method called csv_dump(), which will
-  # be passed the headers.  This should return an Array of fields that can be
-  # serialized for this object.  This method is called once for every object in
-  # the Array.
-  #
-  # The +io+ parameter can be used to serialize to a File, and +options+ can be
-  # anything CSV::new() accepts.
-  #
-  def self.dump(ary_of_objs, io = "", options = Hash.new)
-    obj_template = ary_of_objs.first
-
-    csv = new(io, options)
-
-    # write meta information
-    begin
-      csv << obj_template.class.csv_meta
-    rescue NoMethodError
-      csv << [:class, obj_template.class]
-    end
-
-    # write headers
-    begin
-      headers = obj_template.csv_headers
-    rescue NoMethodError
-      headers = obj_template.instance_variables.sort
-      if obj_template.class.ancestors.find { |cls| cls.to_s =~ /\AStruct\b/ }
-        headers += obj_template.members.map { |mem| "#{mem}=" }.sort
-      end
-    end
-    csv << headers
-
-    # serialize each object
-    ary_of_objs.each do |obj|
-      begin
-        csv << obj.csv_dump(headers)
-      rescue NoMethodError
-        csv << headers.map do |var|
-          if var[0] == ?@
-            obj.instance_variable_get(var)
-          else
-            obj[var[0..-2]]
-          end
-        end
-      end
-    end
-
-    if io.is_a? String
-      csv.string
-    else
-      csv.close
-    end
-  end
-
-  #
-  # This method is the reading counterpart to CSV::dump().  See that method for
-  # a detailed description of the process.
-  #
-  # You can customize loading by adding a class method called csv_load() which
-  # will be passed a Hash of meta information, an Array of headers, and an Array
-  # of fields for the object the method is expected to return.
-  #
-  # Remember that all fields will be Strings after this load.  If you need
-  # something else, use +options+ to setup converters or provide a custom
-  # csv_load() implementation.
-  #
-  def self.load(io_or_str, options = Hash.new)
-    csv = new(io_or_str, options)
-
-    # load meta information
-    meta = Hash[*csv.shift]
-    cls  = meta["class".encode(csv.encoding)].split("::".encode(csv.encoding)).
-                                              inject(Object) do |c, const|
-      c.const_get(const)
-    end
-
-    # load headers
-    headers = csv.shift
-
-    # unserialize each object stored in the file
-    results = csv.inject(Array.new) do |all, row|
-      begin
-        obj = cls.csv_load(meta, headers, row)
-      rescue NoMethodError
-        obj = cls.allocate
-        headers.zip(row) do |name, value|
-          if name[0] == ?@
-            obj.instance_variable_set(name, value)
-          else
-            obj.send(name, value)
-          end
-        end
-      end
-      all << obj
-    end
-
-    csv.close unless io_or_str.is_a? String
-
-    results
-  end
-
-  #
-  # :call-seq:
-  #   filter( options = Hash.new ) { |row| ... }
-  #   filter( input, options = Hash.new ) { |row| ... }
-  #   filter( input, output, options = Hash.new ) { |row| ... }
-  #
-  # This method is a convenience for building Unix-like filters for CSV data.
-  # Each row is yielded to the provided block which can alter it as needed.
-  # After the block returns, the row is appended to +output+ altered or not.
-  #
-  # The +input+ and +output+ arguments can be anything CSV::new() accepts
-  # (generally String or IO objects).  If not given, they default to
-  # <tt>ARGF</tt> and <tt>$stdout</tt>.
-  #
-  # The +options+ parameter is also filtered down to CSV::new() after some
-  # clever key parsing.  Any key beginning with <tt>:in_</tt> or
-  # <tt>:input_</tt> will have that leading identifier stripped and will only
-  # be used in the +options+ Hash for the +input+ object.  Keys starting with
-  # <tt>:out_</tt> or <tt>:output_</tt> affect only +output+.  All other keys
-  # are assigned to both objects.
-  #
-  # The <tt>:output_row_sep</tt> +option+ defaults to
-  # <tt>$INPUT_RECORD_SEPARATOR</tt> (<tt>$/</tt>).
-  #
-  def self.filter(*args)
-    # parse options for input, output, or both
-    in_options, out_options = Hash.new, {row_sep: $INPUT_RECORD_SEPARATOR}
-    if args.last.is_a? Hash
-      args.pop.each do |key, value|
-        case key.to_s
-        when /\Ain(?:put)?_(.+)\Z/
-          in_options[$1.to_sym] = value
-        when /\Aout(?:put)?_(.+)\Z/
-          out_options[$1.to_sym] = value
-        else
-          in_options[key]  = value
-          out_options[key] = value
-        end
-      end
-    end
-    # build input and output wrappers
-    input  = new(args.shift || ARGF,    in_options)
-    output = new(args.shift || $stdout, out_options)
-
-    # read, yield, write
-    input.each do |row|
-      yield row
-      output << row
-    end
-  end
-
-  #
-  # This method is intended as the primary interface for reading CSV files.  You
-  # pass a +path+ and any +options+ you wish to set for the read.  Each row of
-  # file will be passed to the provided +block+ in turn.
-  #
-  # The +options+ parameter can be anything CSV::new() understands.  This method
-  # also understands an additional <tt>:encoding</tt> parameter that you can use
-  # to specify the Encoding of the data in the file to be read. You must provide
-  # this unless your data is in Encoding::default_external().  CSV will use this
-  # to determine how to parse the data.  You may provide a second Encoding to
-  # have the data transcoded as it is read.  For example,
-  # <tt>encoding: "UTF-32BE:UTF-8"</tt> would read UTF-32BE data from the file
-  # but transcode it to UTF-8 before CSV parses it.
-  #
-  def self.foreach(path, options = Hash.new, &block)
-    open(path, options) do |csv|
-      csv.each(&block)
-    end
-  end
-
-  #
-  # :call-seq:
-  #   generate( str, options = Hash.new ) { |csv| ... }
-  #   generate( options = Hash.new ) { |csv| ... }
-  #
-  # This method wraps a String you provide, or an empty default String, in a
-  # CSV object which is passed to the provided block.  You can use the block to
-  # append CSV rows to the String and when the block exits, the final String
-  # will be returned.
-  #
-  # Note that a passed String *is* modfied by this method.  Call dup() before
-  # passing if you need a new String.
-  #
-  # The +options+ parameter can be anything CSV::new() understands.  This method
-  # understands an additional <tt>:encoding</tt> parameter when not passed a
-  # String to set the base Encoding for the output.  CSV needs this hint if you
-  # plan to output non-ASCII compatible data.
-  #
-  def self.generate(*args)
-    # add a default empty String, if none was given
-    if args.first.is_a? String
-      io = StringIO.new(args.shift)
-      io.seek(0, IO::SEEK_END)
-      args.unshift(io)
-    else
-      encoding = (args[-1] = args[-1].dup).delete(:encoding) if args.last.is_a?(Hash)
-      str      = ""
-      str.encode!(encoding) if encoding
-      args.unshift(str)
-    end
-    csv = new(*args)  # wrap
-    yield csv         # yield for appending
-    csv.string        # return final String
-  end
-
-  #
-  # This method is a shortcut for converting a single row (Array) into a CSV
-  # String.
-  #
-  # The +options+ parameter can be anything CSV::new() understands.  This method
-  # understands an additional <tt>:encoding</tt> parameter to set the base
-  # Encoding for the output.  This method will try to guess your Encoding from
-  # the first non-+nil+ field in +row+, if possible, but you may need to use
-  # this parameter as a backup plan.
-  #
-  # The <tt>:row_sep</tt> +option+ defaults to <tt>$INPUT_RECORD_SEPARATOR</tt>
-  # (<tt>$/</tt>) when calling this method.
-  #
-  def self.generate_line(row, options = Hash.new)
-    options  = {row_sep: $INPUT_RECORD_SEPARATOR}.merge(options)
-    encoding = options.delete(:encoding)
-    str      = ""
-    if encoding
-      str.force_encoding(encoding)
-    elsif field = row.find { |f| not f.nil? }
-      str.force_encoding(String(field).encoding)
-    end
-    (new(str, options) << row).string
-  end
-
-  #
-  # :call-seq:
-  #   open( filename, mode = "rb", options = Hash.new ) { |faster_csv| ... }
-  #   open( filename, options = Hash.new ) { |faster_csv| ... }
-  #   open( filename, mode = "rb", options = Hash.new )
-  #   open( filename, options = Hash.new )
-  #
-  # This method opens an IO object, and wraps that with CSV.  This is intended
-  # as the primary interface for writing a CSV file.
-  #
-  # You must pass a +filename+ and may optionally add a +mode+ for Ruby's
-  # open().  You may also pass an optional Hash containing any +options+
-  # CSV::new() understands as the final argument.
-  #
-  # This method works like Ruby's open() call, in that it will pass a CSV object
-  # to a provided block and close it when the block terminates, or it will
-  # return the CSV object when no block is provided.  (*Note*: This is different
-  # from the Ruby 1.8 CSV library which passed rows to the block.  Use
-  # CSV::foreach() for that behavior.)
-  #
-  # You must provide a +mode+ with an embedded Encoding designator unless your
-  # data is in Encoding::default_external().  CSV will check the Encoding of the
-  # underlying IO object (set by the +mode+ you pass) to determine how to parse
-  # the data.   You may provide a second Encoding to have the data transcoded as
-  # it is read just as you can with a normal call to IO::open().  For example,
-  # <tt>"rb:UTF-32BE:UTF-8"</tt> would read UTF-32BE data from the file but
-  # transcode it to UTF-8 before CSV parses it.
-  #
-  # An opened CSV object will delegate to many IO methods for convenience.  You
-  # may call:
-  #
-  # * binmode()
-  # * binmode?()
-  # * close()
-  # * close_read()
-  # * close_write()
-  # * closed?()
-  # * eof()
-  # * eof?()
-  # * external_encoding()
-  # * fcntl()
-  # * fileno()
-  # * flock()
-  # * flush()
-  # * fsync()
-  # * internal_encoding()
-  # * ioctl()
-  # * isatty()
-  # * path()
-  # * pid()
-  # * pos()
-  # * pos=()
-  # * reopen()
-  # * seek()
-  # * stat()
-  # * sync()
-  # * sync=()
-  # * tell()
-  # * to_i()
-  # * to_io()
-  # * truncate()
-  # * tty?()
-  #
-  def self.open(*args)
-    # find the +options+ Hash
-    options = if args.last.is_a? Hash then args.pop else Hash.new end
-    # wrap a File opened with the remaining +args+ with no newline
-    # decorator
-    file_opts = {universal_newline: false}.merge(options)
-    begin
-      f = File.open(*args, file_opts)
-    rescue ArgumentError => e
-      raise unless /needs binmode/ =~ e.message and args.size == 1
-      args << "rb"
-      file_opts = {encoding: Encoding.default_external}.merge(file_opts)
-      retry
-    end
-    csv = new(f, options)
-
-    # handle blocks like Ruby's open(), not like the CSV library
-    if block_given?
-      begin
-        yield csv
-      ensure
-        csv.close
-      end
-    else
-      csv
-    end
-  end
-
-  #
-  # :call-seq:
-  #   parse( str, options = Hash.new ) { |row| ... }
-  #   parse( str, options = Hash.new )
-  #
-  # This method can be used to easily parse CSV out of a String.  You may either
-  # provide a +block+ which will be called with each row of the String in turn,
-  # or just use the returned Array of Arrays (when no +block+ is given).
-  #
-  # You pass your +str+ to read from, and an optional +options+ Hash containing
-  # anything CSV::new() understands.
-  #
-  def self.parse(*args, &block)
-    csv = new(*args)
-    if block.nil?  # slurp contents, if no block is given
-      begin
-        csv.read
-      ensure
-        csv.close
-      end
-    else           # or pass each row to a provided block
-      csv.each(&block)
-    end
-  end
-
-  #
-  # This method is a shortcut for converting a single line of a CSV String into
-  # a into an Array.  Note that if +line+ contains multiple rows, anything
-  # beyond the first row is ignored.
-  #
-  # The +options+ parameter can be anything CSV::new() understands.
-  #
-  def self.parse_line(line, options = Hash.new)
-    new(line, options).shift
-  end
-
-  #
-  # Use to slurp a CSV file into an Array of Arrays.  Pass the +path+ to the
-  # file and any +options+ CSV::new() understands.  This method also understands
-  # an additional <tt>:encoding</tt> parameter that you can use to specify the
-  # Encoding of the data in the file to be read. You must provide this unless
-  # your data is in Encoding::default_external().  CSV will use this to determine
-  # how to parse the data.  You may provide a second Encoding to have the data
-  # transcoded as it is read.  For example,
-  # <tt>encoding: "UTF-32BE:UTF-8"</tt> would read UTF-32BE data from the file
-  # but transcode it to UTF-8 before CSV parses it.
-  #
-  def self.read(path, *options)
-    open(path, *options) { |csv| csv.read }
-  end
-
-  # Alias for CSV::read().
-  def self.readlines(*args)
-    read(*args)
-  end
-
-  #
-  # A shortcut for:
-  #
-  #   CSV.read( path, { headers:           true,
-  #                     converters:        :numeric,
-  #                     header_converters: :symbol }.merge(options) )
-  #
-  def self.table(path, options = Hash.new)
-    read( path, { headers:           true,
-                  converters:        :numeric,
-                  header_converters: :symbol }.merge(options) )
-  end
-
-  #
-  # This constructor will wrap either a String or IO object passed in +data+ for
-  # reading and/or writing.  In addition to the CSV instance methods, several IO
-  # methods are delegated.  (See CSV::open() for a complete list.)  If you pass
-  # a String for +data+, you can later retrieve it (after writing to it, for
-  # example) with CSV.string().
-  #
-  # Note that a wrapped String will be positioned at at the beginning (for
-  # reading).  If you want it at the end (for writing), use CSV::generate().
-  # If you want any other positioning, pass a preset StringIO object instead.
-  #
-  # You may set any reading and/or writing preferences in the +options+ Hash.
-  # Available options are:
-  #
-  # <b><tt>:col_sep</tt></b>::            The String placed between each field.
-  #                                       This String will be transcoded into
-  #                                       the data's Encoding before parsing.
-  # <b><tt>:row_sep</tt></b>::            The String appended to the end of each
-  #                                       row.  This can be set to the special
-  #                                       <tt>:auto</tt> setting, which requests
-  #                                       that CSV automatically discover this
-  #                                       from the data.  Auto-discovery reads
-  #                                       ahead in the data looking for the next
-  #                                       <tt>"\r\n"</tt>, <tt>"\n"</tt>, or
-  #                                       <tt>"\r"</tt> sequence.  A sequence
-  #                                       will be selected even if it occurs in
-  #                                       a quoted field, assuming that you
-  #                                       would have the same line endings
-  #                                       there.  If none of those sequences is
-  #                                       found, +data+ is <tt>ARGF</tt>,
-  #                                       <tt>STDIN</tt>, <tt>STDOUT</tt>, or
-  #                                       <tt>STDERR</tt>, or the stream is only
-  #                                       available for output, the default
-  #                                       <tt>$INPUT_RECORD_SEPARATOR</tt>
-  #                                       (<tt>$/</tt>) is used.  Obviously,
-  #                                       discovery takes a little time.  Set
-  #                                       manually if speed is important.  Also
-  #                                       note that IO objects should be opened
-  #                                       in binary mode on Windows if this
-  #                                       feature will be used as the
-  #                                       line-ending translation can cause
-  #                                       problems with resetting the document
-  #                                       position to where it was before the
-  #                                       read ahead. This String will be
-  #                                       transcoded into the data's Encoding
-  #                                       before parsing.
-  # <b><tt>:quote_char</tt></b>::         The character used to quote fields.
-  #                                       This has to be a single character
-  #                                       String.  This is useful for
-  #                                       application that incorrectly use
-  #                                       <tt>'</tt> as the quote character
-  #                                       instead of the correct <tt>"</tt>.
-  #                                       CSV will always consider a double
-  #                                       sequence this character to be an
-  #                                       escaped quote. This String will be
-  #                                       transcoded into the data's Encoding
-  #                                       before parsing.
-  # <b><tt>:field_size_limit</tt></b>::   This is a maximum size CSV will read
-  #                                       ahead looking for the closing quote
-  #                                       for a field.  (In truth, it reads to
-  #                                       the first line ending beyond this
-  #                                       size.)  If a quote cannot be found
-  #                                       within the limit CSV will raise a
-  #                                       MalformedCSVError, assuming the data
-  #                                       is faulty.  You can use this limit to
-  #                                       prevent what are effectively DoS
-  #                                       attacks on the parser.  However, this
-  #                                       limit can cause a legitimate parse to
-  #                                       fail and thus is set to +nil+, or off,
-  #                                       by default.
-  # <b><tt>:converters</tt></b>::         An Array of names from the Converters
-  #                                       Hash and/or lambdas that handle custom
-  #                                       conversion.  A single converter
-  #                                       doesn't have to be in an Array.  All
-  #                                       built-in converters try to transcode
-  #                                       fields to UTF-8 before converting.
-  #                                       The conversion will fail if the data
-  #                                       cannot be transcoded, leaving the
-  #                                       field unchanged.
-  # <b><tt>:unconverted_fields</tt></b>:: If set to +true+, an
-  #                                       unconverted_fields() method will be
-  #                                       added to all returned rows (Array or
-  #                                       CSV::Row) that will return the fields
-  #                                       as they were before conversion.  Note
-  #                                       that <tt>:headers</tt> supplied by
-  #                                       Array or String were not fields of the
-  #                                       document and thus will have an empty
-  #                                       Array attached.
-  # <b><tt>:headers</tt></b>::            If set to <tt>:first_row</tt> or
-  #                                       +true+, the initial row of the CSV
-  #                                       file will be treated as a row of
-  #                                       headers.  If set to an Array, the
-  #                                       contents will be used as the headers.
-  #                                       If set to a String, the String is run
-  #                                       through a call of CSV::parse_line()
-  #                                       with the same <tt>:col_sep</tt>,
-  #                                       <tt>:row_sep</tt>, and
-  #                                       <tt>:quote_char</tt> as this instance
-  #                                       to produce an Array of headers.  This
-  #                                       setting causes CSV#shift() to return
-  #                                       rows as CSV::Row objects instead of
-  #                                       Arrays and CSV#read() to return
-  #                                       CSV::Table objects instead of an Array
-  #                                       of Arrays.
-  # <b><tt>:return_headers</tt></b>::     When +false+, header rows are silently
-  #                                       swallowed.  If set to +true+, header
-  #                                       rows are returned in a CSV::Row object
-  #                                       with identical headers and
-  #                                       fields (save that the fields do not go
-  #                                       through the converters).
-  # <b><tt>:write_headers</tt></b>::      When +true+ and <tt>:headers</tt> is
-  #                                       set, a header row will be added to the
-  #                                       output.
-  # <b><tt>:header_converters</tt></b>::  Identical in functionality to
-  #                                       <tt>:converters</tt> save that the
-  #                                       conversions are only made to header
-  #                                       rows.  All built-in converters try to
-  #                                       transcode headers to UTF-8 before
-  #                                       converting.  The conversion will fail
-  #                                       if the data cannot be transcoded,
-  #                                       leaving the header unchanged.
-  # <b><tt>:skip_blanks</tt></b>::        When set to a +true+ value, CSV will
-  #                                       skip over any rows with no content.
-  # <b><tt>:force_quotes</tt></b>::       When set to a +true+ value, CSV will
-  #                                       quote all CSV fields it creates.
-  #
-  # See CSV::DEFAULT_OPTIONS for the default settings.
-  #
-  # Options cannot be overridden in the instance methods for performance reasons,
-  # so be sure to set what you want here.
-  #
-  def initialize(data, options = Hash.new)
-    # build the options for this read/write
-    options = DEFAULT_OPTIONS.merge(options)
-
-    # create the IO object we will read from
-    @io       = data.is_a?(String) ? StringIO.new(data) : data
-    # honor the IO encoding if we can, otherwise default to ASCII-8BIT
-    @encoding = raw_encoding(nil) ||
-                ( if encoding = options.delete(:internal_encoding)
-                    case encoding
-                    when Encoding; encoding
-                    else Encoding.find(encoding)
-                    end
-                  end ) ||
-                ( case encoding = options.delete(:encoding)
-                  when Encoding; encoding
-                  when /\A[^:]+/; Encoding.find($&)
-                  end ) ||
-                Encoding.default_internal || Encoding.default_external
-    #
-    # prepare for building safe regular expressions in the target encoding,
-    # if we can transcode the needed characters
-    #
-    @re_esc   =   "\\".encode(@encoding) rescue ""
-    @re_chars =   /#{%"[-][\\.^$?*+{}()|# \r\n\t\f\v]".encode(@encoding)}/
-    # @re_chars =   /#{%"[-][\\.^$?*+{}()|# \r\n\t\f\v]".encode(@encoding, fallback: proc{""})}/
-
-    init_separators(options)
-    init_parsers(options)
-    init_converters(options)
-    init_headers(options)
-
-    options.delete(:encoding)
-    options.delete(:internal_encoding)
-    options.delete(:external_encoding)
-    unless options.empty?
-      raise ArgumentError, "Unknown options:  #{options.keys.join(', ')}."
-    end
-
-    # track our own lineno since IO gets confused about line-ends is CSV fields
-    @lineno = 0
-  end
-
-  #
-  # The encoded <tt>:col_sep</tt> used in parsing and writing.  See CSV::new
-  # for details.
-  #
-  attr_reader :col_sep
-  #
-  # The encoded <tt>:row_sep</tt> used in parsing and writing.  See CSV::new
-  # for details.
-  #
-  attr_reader :row_sep
-  #
-  # The encoded <tt>:quote_char</tt> used in parsing and writing.  See CSV::new
-  # for details.
-  #
-  attr_reader :quote_char
-  # The limit for field size, if any.  See CSV::new for details.
-  attr_reader :field_size_limit
-  #
-  # Returns the current list of converters in effect.  See CSV::new for details.
-  # Built-in converters will be returned by name, while others will be returned
-  # as is.
-  #
-  def converters
-    @converters.map do |converter|
-      name = Converters.rassoc(converter)
-      name ? name.first : converter
-    end
-  end
-  #
-  # Returns +true+ if unconverted_fields() to parsed results.  See CSV::new
-  # for details.
-  #
-  def unconverted_fields?() @unconverted_fields end
-  #
-  # Returns +nil+ if headers will not be used, +true+ if they will but have not
-  # yet been read, or the actual headers after they have been read.  See
-  # CSV::new for details.
-  #
-  def headers
-    @headers || true if @use_headers
-  end
-  #
-  # Returns +true+ if headers will be returned as a row of results.
-  # See CSV::new for details.
-  #
-  def return_headers?()     @return_headers     end
-  # Returns +true+ if headers are written in output. See CSV::new for details.
-  def write_headers?()      @write_headers      end
-  #
-  # Returns the current list of converters in effect for headers.  See CSV::new
-  # for details.  Built-in converters will be returned by name, while others
-  # will be returned as is.
-  #
-  def header_converters
-    @header_converters.map do |converter|
-      name = HeaderConverters.rassoc(converter)
-      name ? name.first : converter
-    end
-  end
-  #
-  # Returns +true+ blank lines are skipped by the parser. See CSV::new
-  # for details.
-  #
-  def skip_blanks?()        @skip_blanks        end
-  # Returns +true+ if all output fields are quoted. See CSV::new for details.
-  def force_quotes?()       @force_quotes       end
-
-  #
-  # The Encoding CSV is parsing or writing in.  This will be the Encoding you
-  # receive parsed data in and/or the Encoding data will be written in.
-  #
-  attr_reader :encoding
-
-  #
-  # The line number of the last row read from this file.  Fields with nested
-  # line-end characters will not affect this count.
-  #
-  attr_reader :lineno
-
-  ### IO and StringIO Delegation ###
-
-  extend Forwardable
-  def_delegators :@io, :binmode, :binmode?, :close, :close_read, :close_write,
-                       :closed?, :eof, :eof?, :external_encoding, :fcntl,
-                       :fileno, :flock, :flush, :fsync, :internal_encoding,
-                       :ioctl, :isatty, :path, :pid, :pos, :pos=, :reopen,
-                       :seek, :stat, :string, :sync, :sync=, :tell, :to_i,
-                       :to_io, :truncate, :tty?
-
-  # Rewinds the underlying IO object and resets CSV's lineno() counter.
-  def rewind
-    @headers = nil
-    @lineno  = 0
-
-    @io.rewind
-  end
-
-  ### End Delegation ###
-
-  #
-  # The primary write method for wrapped Strings and IOs, +row+ (an Array or
-  # CSV::Row) is converted to CSV and appended to the data source.  When a
-  # CSV::Row is passed, only the row's fields() are appended to the output.
-  #
-  # The data source must be open for writing.
-  #
-  def <<(row)
-    # make sure headers have been assigned
-    if header_row? and [Array, String].include? @use_headers.class
-      parse_headers  # won't read data for Array or String
-      self << @headers if @write_headers
-    end
-
-    # handle CSV::Row objects and Hashes
-    row = case row
-          when self.class::Row then row.fields
-          when Hash            then @headers.map { |header| row[header] }
-          else                      row
-          end
-
-    @headers =  row if header_row?
-    @lineno  += 1
-
-    output = row.map(&@quote).join(@col_sep) + @row_sep  # quote and separate
-    if @io.is_a?(StringIO)             and
-       output.encoding != raw_encoding and
-       (compatible_encoding = Encoding.compatible?(@io.string, output))
-      @io = StringIO.new(@io.string.force_encoding(compatible_encoding))
-      @io.seek(0, IO::SEEK_END)
-    end
-    @io << output
-
-    self  # for chaining
-  end
-  alias_method :add_row, :<<
-  alias_method :puts,    :<<
-
-  #
-  # :call-seq:
-  #   convert( name )
-  #   convert { |field| ... }
-  #   convert { |field, field_info| ... }
-  #
-  # You can use this method to install a CSV::Converters built-in, or provide a
-  # block that handles a custom conversion.
-  #
-  # If you provide a block that takes one argument, it will be passed the field
-  # and is expected to return the converted value or the field itself.  If your
-  # block takes two arguments, it will also be passed a CSV::FieldInfo Struct,
-  # containing details about the field.  Again, the block should return a
-  # converted field or the field itself.
-  #
-  def convert(name = nil, &converter)
-    add_converter(:converters, self.class::Converters, name, &converter)
-  end
-
-  #
-  # :call-seq:
-  #   header_convert( name )
-  #   header_convert { |field| ... }
-  #   header_convert { |field, field_info| ... }
-  #
-  # Identical to CSV#convert(), but for header rows.
-  #
-  # Note that this method must be called before header rows are read to have any
-  # effect.
-  #
-  def header_convert(name = nil, &converter)
-    add_converter( :header_converters,
-                   self.class::HeaderConverters,
-                   name,
-                   &converter )
-  end
-
-  include Enumerable
-
-  #
-  # Yields each row of the data source in turn.
-  #
-  # Support for Enumerable.
-  #
-  # The data source must be open for reading.
-  #
-  def each
-    if block_given?
-      while row = shift
-        yield row
-      end
-    else
-      to_enum
-    end
-  end
-
-  #
-  # Slurps the remaining rows and returns an Array of Arrays.
-  #
-  # The data source must be open for reading.
-  #
-  def read
-    rows = to_a
-    if @use_headers
-      Table.new(rows)
-    else
-      rows
-    end
-  end
-  alias_method :readlines, :read
-
-  # Returns +true+ if the next row read will be a header row.
-  def header_row?
-    @use_headers and @headers.nil?
-  end
-
-  #
-  # The primary read method for wrapped Strings and IOs, a single row is pulled
-  # from the data source, parsed and returned as an Array of fields (if header
-  # rows are not used) or a CSV::Row (when header rows are used).
-  #
-  # The data source must be open for reading.
-  #
-  def shift
-    #########################################################################
-    ### This method is purposefully kept a bit long as simple conditional ###
-    ### checks are faster than numerous (expensive) method calls.         ###
-    #########################################################################
-
-    # handle headers not based on document content
-    if header_row? and @return_headers and
-       [Array, String].include? @use_headers.class
-      if @unconverted_fields
-        return add_unconverted_fields(parse_headers, Array.new)
-      else
-        return parse_headers
-      end
-    end
-
-    #
-    # it can take multiple calls to <tt>@io.gets()</tt> to get a full line,
-    # because of \r and/or \n characters embedded in quoted fields
-    #
-    in_extended_col = false
-    csv             = Array.new
-
-    loop do
-      # add another read to the line
-      unless parse = @io.gets(@row_sep)
-        return nil
-      end
-
-      parse.sub!(@parsers[:line_end], "")
-
-      if csv.empty?
-        #
-        # I believe a blank line should be an <tt>Array.new</tt>, not Ruby 1.8
-        # CSV's <tt>[nil]</tt>
-        #
-        if parse.empty?
-          @lineno += 1
-          if @skip_blanks
-            next
-          elsif @unconverted_fields
-            return add_unconverted_fields(Array.new, Array.new)
-          elsif @use_headers
-            return self.class::Row.new(Array.new, Array.new)
-          else
-            return Array.new
-          end
-        end
-      end
-
-      parts =  parse.split(@col_sep, -1)
-      if parts.empty?
-        if in_extended_col
-          csv[-1] << @col_sep   # will be replaced with a @row_sep after the parts.each loop
-        else
-          csv << nil
-        end
-      end
-
-      # This loop is the hot path of csv parsing. Some things may be non-dry
-      # for a reason. Make sure to benchmark when refactoring.
-      parts.each do |part|
-        if in_extended_col
-          # If we are continuing a previous column
-          if part[-1] == @quote_char && part.count(@quote_char) % 2 != 0
-            # extended column ends
-            csv.last << part[0..-2]
-            if csv.last =~ @parsers[:stray_quote]
-              raise MalformedCSVError,
-                    "Missing or stray quote in line #{lineno + 1}"
-            end
-            csv.last.gsub!(@quote_char * 2, @quote_char)
-            in_extended_col = false
-          else
-            csv.last << part
-            csv.last << @col_sep
-          end
-        elsif part[0] == @quote_char
-          # If we are staring a new quoted column
-          if part[-1] != @quote_char || part.count(@quote_char) % 2 != 0
-            # start an extended column
-            csv             << part[1..-1]
-            csv.last        << @col_sep
-            in_extended_col =  true
-          else
-            # regular quoted column
-            csv << part[1..-2]
-            if csv.last =~ @parsers[:stray_quote]
-              raise MalformedCSVError,
-                    "Missing or stray quote in line #{lineno + 1}"
-            end
-            csv.last.gsub!(@quote_char * 2, @quote_char)
-          end
-        elsif part =~ @parsers[:quote_or_nl]
-          # Unquoted field with bad characters.
-          if part =~ @parsers[:nl_or_lf]
-            raise MalformedCSVError, "Unquoted fields do not allow " +
-                                     "\\r or \\n (line #{lineno + 1})."
-          else
-            raise MalformedCSVError, "Illegal quoting in line #{lineno + 1}."
-          end
-        else
-          # Regular ole unquoted field.
-          csv << (part.empty? ? nil : part)
-        end
-      end
-
-      # Replace tacked on @col_sep with @row_sep if we are still in an extended
-      # column.
-      csv[-1][-1] = @row_sep if in_extended_col
-
-      if in_extended_col
-        # if we're at eof?(), a quoted field wasn't closed...
-        if @io.eof?
-          raise MalformedCSVError,
-                "Unclosed quoted field on line #{lineno + 1}."
-        elsif @field_size_limit and csv.last.size >= @field_size_limit
-          raise MalformedCSVError, "Field size exceeded on line #{lineno + 1}."
-        end
-        # otherwise, we need to loop and pull some more data to complete the row
-      else
-        @lineno += 1
-
-        # save fields unconverted fields, if needed...
-        unconverted = csv.dup if @unconverted_fields
-
-        # convert fields, if needed...
-        csv = convert_fields(csv) unless @use_headers or @converters.empty?
-        # parse out header rows and handle CSV::Row conversions...
-        csv = parse_headers(csv)  if     @use_headers
-
-        # inject unconverted fields and accessor, if requested...
-        if @unconverted_fields and not csv.respond_to? :unconverted_fields
-          add_unconverted_fields(csv, unconverted)
-        end
-
-        # return the results
-        break csv
-      end
-    end
-  end
-  alias_method :gets,     :shift
-  alias_method :readline, :shift
-
-  #
-  # Returns a simplified description of the key CSV attributes in an
-  # ASCII compatible String.
-  #
-  def inspect
-    str = ["<#", self.class.to_s, " io_type:"]
-    # show type of wrapped IO
-    if    @io == $stdout then str << "$stdout"
-    elsif @io == $stdin  then str << "$stdin"
-    elsif @io == $stderr then str << "$stderr"
-    else                      str << @io.class.to_s
-    end
-    # show IO.path(), if available
-    if @io.respond_to?(:path) and (p = @io.path)
-      str << " io_path:" << p.inspect
-    end
-    # show encoding
-    str << " encoding:" << @encoding.name
-    # show other attributes
-    %w[ lineno     col_sep     row_sep
-        quote_char skip_blanks ].each do |attr_name|
-      if a = instance_variable_get("@#{attr_name}")
-        str << " " << attr_name << ":" << a.inspect
-      end
-    end
-    if @use_headers
-      str << " headers:" << headers.inspect
-    end
-    str << ">"
-    begin
-      str.join('')
-    rescue  # any encoding error
-      str.map do |s|
-        e = Encoding::Converter.asciicompat_encoding(s.encoding)
-        e ? s.encode(e) : s.force_encoding("ASCII-8BIT")
-      end.join('')
-    end
-  end
-
-  private
-
-  #
-  # Stores the indicated separators for later use.
-  #
-  # If auto-discovery was requested for <tt>@row_sep</tt>, this method will read
-  # ahead in the <tt>@io</tt> and try to find one.  +ARGF+, +STDIN+, +STDOUT+,
-  # +STDERR+ and any stream open for output only with a default
-  # <tt>@row_sep</tt> of <tt>$INPUT_RECORD_SEPARATOR</tt> (<tt>$/</tt>).
-  #
-  # This method also establishes the quoting rules used for CSV output.
-  #
-  def init_separators(options)
-    # store the selected separators
-    @col_sep    = options.delete(:col_sep).to_s.encode(@encoding)
-    @row_sep    = options.delete(:row_sep)  # encode after resolving :auto
-    @quote_char = options.delete(:quote_char).to_s.encode(@encoding)
-
-    if @quote_char.length != 1
-      raise ArgumentError, ":quote_char has to be a single character String"
-    end
-
-    #
-    # automatically discover row separator when requested
-    # (not fully encoding safe)
-    #
-    if @row_sep == :auto
-      if [ARGF, STDIN, STDOUT, STDERR].include?(@io) or
-         (defined?(Zlib) and @io.class == Zlib::GzipWriter)
-        @row_sep = $INPUT_RECORD_SEPARATOR
-      else
-        begin
-          #
-          # remember where we were (pos() will raise an axception if @io is pipe
-          # or not opened for reading)
-          #
-          saved_pos = @io.pos
-          while @row_sep == :auto
-            #
-            # if we run out of data, it's probably a single line
-            # (ensure will set default value)
-            #
-            break unless sample = @io.gets(nil, 1024)
-            # extend sample if we're unsure of the line ending
-            if sample.end_with? encode_str("\r")
-              sample << (@io.gets(nil, 1) || "")
-            end
-
-            # try to find a standard separator
-            if sample =~ encode_re("\r\n?|\n")
-              @row_sep = $&
-              break
-            end
-          end
-
-          # tricky seek() clone to work around GzipReader's lack of seek()
-          @io.rewind
-          # reset back to the remembered position
-          while saved_pos > 1024  # avoid loading a lot of data into memory
-            @io.read(1024)
-            saved_pos -= 1024
-          end
-          @io.read(saved_pos) if saved_pos.nonzero?
-        rescue IOError         # not opened for reading
-          # do nothing:  ensure will set default
-        rescue NoMethodError   # Zlib::GzipWriter doesn't have some IO methods
-          # do nothing:  ensure will set default
-        rescue SystemCallError # pipe
-          # do nothing:  ensure will set default
-        ensure
-          #
-          # set default if we failed to detect
-          # (stream not opened for reading, a pipe, or a single line of data)
-          #
-          @row_sep = $INPUT_RECORD_SEPARATOR if @row_sep == :auto
-        end
-      end
-    end
-    @row_sep = @row_sep.to_s.encode(@encoding)
-
-    # establish quoting rules
-    @force_quotes   = options.delete(:force_quotes)
-    do_quote        = lambda do |field|
-      field         = String(field)
-      encoded_quote = @quote_char.encode(field.encoding)
-      encoded_quote                                +
-      field.gsub(encoded_quote, encoded_quote * 2) +
-      encoded_quote
-    end
-    quotable_chars = encode_str("\r\n", @col_sep, @quote_char)
-    @quote         = if @force_quotes
-      do_quote
-    else
-      lambda do |field|
-        if field.nil?  # represent +nil+ fields as empty unquoted fields
-          ""
-        else
-          field = String(field)  # Stringify fields
-          # represent empty fields as empty quoted fields
-          if field.empty? or
-             field.count(quotable_chars).nonzero?
-            do_quote.call(field)
-          else
-            field  # unquoted field
-          end
-        end
-      end
-    end
-  end
-
-  # Pre-compiles parsers and stores them by name for access during reads.
-  def init_parsers(options)
-    # store the parser behaviors
-    @skip_blanks      = options.delete(:skip_blanks)
-    @field_size_limit = options.delete(:field_size_limit)
-
-    # prebuild Regexps for faster parsing
-    esc_row_sep = escape_re(@row_sep)
-    esc_quote   = escape_re(@quote_char)
-    @parsers = {
-      # for detecting parse errors
-      quote_or_nl:    encode_re("[", esc_quote, "\r\n]"),
-      nl_or_lf:       encode_re("[\r\n]"),
-      stray_quote:    encode_re( "[^", esc_quote, "]", esc_quote,
-                                 "[^", esc_quote, "]" ),
-      # safer than chomp!()
-      line_end:       encode_re(esc_row_sep, "\\z"),
-      # illegal unquoted characters
-      return_newline: encode_str("\r\n")
-    }
-  end
-
-  #
-  # Loads any converters requested during construction.
-  #
-  # If +field_name+ is set <tt>:converters</tt> (the default) field converters
-  # are set.  When +field_name+ is <tt>:header_converters</tt> header converters
-  # are added instead.
-  #
-  # The <tt>:unconverted_fields</tt> option is also actived for
-  # <tt>:converters</tt> calls, if requested.
-  #
-  def init_converters(options, field_name = :converters)
-    if field_name == :converters
-      @unconverted_fields = options.delete(:unconverted_fields)
-    end
-
-    instance_variable_set("@#{field_name}", Array.new)
-
-    # find the correct method to add the converters
-    convert = method(field_name.to_s.sub(/ers\Z/, ""))
-
-    # load converters
-    unless options[field_name].nil?
-      # allow a single converter not wrapped in an Array
-      unless options[field_name].is_a? Array
-        options[field_name] = [options[field_name]]
-      end
-      # load each converter...
-      options[field_name].each do |converter|
-        if converter.is_a? Proc  # custom code block
-          convert.call(&converter)
-        else                     # by name
-          convert.call(converter)
-        end
-      end
-    end
-
-    options.delete(field_name)
-  end
-
-  # Stores header row settings and loads header converters, if needed.
-  def init_headers(options)
-    @use_headers    = options.delete(:headers)
-    @return_headers = options.delete(:return_headers)
-    @write_headers  = options.delete(:write_headers)
-
-    # headers must be delayed until shift(), in case they need a row of content
-    @headers = nil
-
-    init_converters(options, :header_converters)
-  end
-
-  #
-  # The actual work method for adding converters, used by both CSV.convert() and
-  # CSV.header_convert().
-  #
-  # This method requires the +var_name+ of the instance variable to place the
-  # converters in, the +const+ Hash to lookup named converters in, and the
-  # normal parameters of the CSV.convert() and CSV.header_convert() methods.
-  #
-  def add_converter(var_name, const, name = nil, &converter)
-    if name.nil?  # custom converter
-      instance_variable_get("@#{var_name}") << converter
-    else          # named converter
-      combo = const[name]
-      case combo
-      when Array  # combo converter
-        combo.each do |converter_name|
-          add_converter(var_name, const, converter_name)
-        end
-      else        # individual named converter
-        instance_variable_get("@#{var_name}") << combo
-      end
-    end
-  end
-
-  #
-  # Processes +fields+ with <tt>@converters</tt>, or <tt>@header_converters</tt>
-  # if +headers+ is passed as +true+, returning the converted field set.  Any
-  # converter that changes the field into something other than a String halts
-  # the pipeline of conversion for that field.  This is primarily an efficiency
-  # shortcut.
-  #
-  def convert_fields(fields, headers = false)
-    # see if we are converting headers or fields
-    converters = headers ? @header_converters : @converters
-
-    fields.map.with_index do |field, index|
-      converters.each do |converter|
-        field = if converter.arity == 1  # straight field converter
-          converter[field]
-        else                             # FieldInfo converter
-          header = @use_headers && !headers ? @headers[index] : nil
-          converter[field, FieldInfo.new(index, lineno, header)]
-        end
-        break unless field.is_a? String  # short-curcuit pipeline for speed
-      end
-      field  # final state of each field, converted or original
-    end
-  end
-
-  #
-  # This method is used to turn a finished +row+ into a CSV::Row.  Header rows
-  # are also dealt with here, either by returning a CSV::Row with identical
-  # headers and fields (save that the fields do not go through the converters)
-  # or by reading past them to return a field row. Headers are also saved in
-  # <tt>@headers</tt> for use in future rows.
-  #
-  # When +nil+, +row+ is assumed to be a header row not based on an actual row
-  # of the stream.
-  #
-  def parse_headers(row = nil)
-    if @headers.nil?                # header row
-      @headers = case @use_headers  # save headers
-                 # Array of headers
-                 when Array then @use_headers
-                 # CSV header String
-                 when String
-                   self.class.parse_line( @use_headers,
-                                          col_sep:    @col_sep,
-                                          row_sep:    @row_sep,
-                                          quote_char: @quote_char )
-                 # first row is headers
-                 else            row
-                 end
-
-      # prepare converted and unconverted copies
-      row      = @headers                       if row.nil?
-      @headers = convert_fields(@headers, true)
-
-      if @return_headers                                     # return headers
-        return self.class::Row.new(@headers, row, true)
-      elsif not [Array, String].include? @use_headers.class  # skip to field row
-        return shift
-      end
-    end
-
-    self.class::Row.new(@headers, convert_fields(row))  # field row
-  end
-
-  #
-  # This method injects an instance variable <tt>unconverted_fields</tt> into
-  # +row+ and an accessor method for +row+ called unconverted_fields().  The
-  # variable is set to the contents of +fields+.
-  #
-  def add_unconverted_fields(row, fields)
-    class << row
-      attr_reader :unconverted_fields
-    end
-    row.instance_eval { @unconverted_fields = fields }
-    row
-  end
-
-  #
-  # This method is an encoding safe version of Regexp::escape().  It will escape
-  # any characters that would change the meaning of a regular expression in the
-  # encoding of +str+.  Regular expression characters that cannot be transcoded
-  # to the target encoding will be skipped and no escaping will be performed if
-  # a backslash cannot be transcoded.
-  #
-  def escape_re(str)
-    str.gsub(@re_chars) {|c| @re_esc + c}
-  end
-
-  #
-  # Builds a regular expression in <tt>@encoding</tt>.  All +chunks+ will be
-  # transcoded to that encoding.
-  #
-  def encode_re(*chunks)
-    Regexp.new(encode_str(*chunks))
-  end
-
-  #
-  # Builds a String in <tt>@encoding</tt>.  All +chunks+ will be transcoded to
-  # that encoding.
-  #
-  def encode_str(*chunks)
-    chunks.map { |chunk| chunk.encode(@encoding.name) }.join('')
-  end
-
-  private
-
-  # 
-  # Returns the encoding of the internal IO object or the +default+ if the 
-  # encoding cannot be determined.
-  #
-  def raw_encoding(default = Encoding::ASCII_8BIT)
-    if @io.respond_to? :internal_encoding
-      @io.internal_encoding || @io.external_encoding
-    elsif @io.is_a? StringIO
-      @io.string.encoding
-    elsif @io.respond_to? :encoding
-      @io.encoding
-    else
-      default
-    end
-  end
-end
-
-# Another name for CSV::instance().
-def CSV(*args, &block)
-  CSV.instance(*args, &block)
-end
-
-class Array
-  # Equivalent to <tt>CSV::generate_line(self, options)</tt>.
-  def to_csv(options = Hash.new)
-    CSV.generate_line(self, options)
-  end
-end
-
-class String
-  # Equivalent to <tt>CSV::parse_line(self, options)</tt>.
-  def parse_csv(options = Hash.new)
-    CSV.parse_line(self, options)
-  end
-end
diff --git a/lib/debug.rb b/lib/debug.rb
deleted file mode 100644
index e99f69826a..0000000000
--- a/lib/debug.rb
+++ /dev/null
@@ -1,907 +0,0 @@
-# Copyright (C) 2000  Network Applied Communication Laboratory, Inc.
-# Copyright (C) 2000  Information-technology Promotion Agency, Japan
-# Copyright (C) 2000-2003  NAKAMURA, Hiroshi  <nahi@ruby-lang.org>
-
-require 'continuation'
-
-if $SAFE > 0
-  STDERR.print "-r debug.rb is not available in safe mode\n"
-  exit 1
-end
-
-require 'tracer'
-require 'pp'
-
-class Tracer
-  def Tracer.trace_func(*vars)
-    Single.trace_func(*vars)
-  end
-end
-
-SCRIPT_LINES__ = {} unless defined? SCRIPT_LINES__
-
-class DEBUGGER__
-  MUTEX = Mutex.new
-
-  class Context
-    DEBUG_LAST_CMD = []
-
-    begin
-      require 'readline'
-      def readline(prompt, hist)
-        Readline::readline(prompt, hist)
-      end
-    rescue LoadError
-      def readline(prompt, hist)
-        STDOUT.print prompt
-        STDOUT.flush
-        line = STDIN.gets
-        exit unless line
-        line.chomp!
-        line
-      end
-      USE_READLINE = false
-    end
-
-    def initialize
-      if Thread.current == Thread.main
-        @stop_next = 1
-      else
-        @stop_next = 0
-      end
-      @last_file = nil
-      @file = nil
-      @line = nil
-      @no_step = nil
-      @frames = []
-      @finish_pos = 0
-      @trace = false
-      @catch = "StandardError"
-      @suspend_next = false
-    end
-
-    def stop_next(n=1)
-      @stop_next = n
-    end
-
-    def set_suspend
-      @suspend_next = true
-    end
-
-    def clear_suspend
-      @suspend_next = false
-    end
-
-    def suspend_all
-      DEBUGGER__.suspend
-    end
-
-    def resume_all
-      DEBUGGER__.resume
-    end
-
-    def check_suspend
-      while MUTEX.synchronize {
-          if @suspend_next
-            DEBUGGER__.waiting.push Thread.current
-            @suspend_next = false
-            true
-          end
-        }
-      end
-    end
-
-    def trace?
-      @trace
-    end
-
-    def set_trace(arg)
-      @trace = arg
-    end
-
-    def stdout
-      DEBUGGER__.stdout
-    end
-
-    def break_points
-      DEBUGGER__.break_points
-    end
-
-    def display
-      DEBUGGER__.display
-    end
-
-    def context(th)
-      DEBUGGER__.context(th)
-    end
-
-    def set_trace_all(arg)
-      DEBUGGER__.set_trace(arg)
-    end
-
-    def set_last_thread(th)
-      DEBUGGER__.set_last_thread(th)
-    end
-
-    def debug_eval(str, binding)
-      begin
-        eval(str, binding)
-      rescue StandardError, ScriptError => e
-        at = eval("caller(1)", binding)
-        stdout.printf "%s:%s\n", at.shift, e.to_s.sub(/\(eval\):1:(in `.*?':)?/, '')
-        for i in at
-          stdout.printf "\tfrom %s\n", i
-        end
-        throw :debug_error
-      end
-    end
-
-    def debug_silent_eval(str, binding)
-      begin
-        eval(str, binding)
-      rescue StandardError, ScriptError
-        nil
-      end
-    end
-
-    def var_list(ary, binding)
-      ary.sort!
-      for v in ary
-        stdout.printf "  %s => %s\n", v, eval(v.to_s, binding).inspect
-      end
-    end
-
-    def debug_variable_info(input, binding)
-      case input
-      when /^\s*g(?:lobal)?\s*$/
-        var_list(global_variables, binding)
-
-      when /^\s*l(?:ocal)?\s*$/
-        var_list(eval("local_variables", binding), binding)
-
-      when /^\s*i(?:nstance)?\s+/
-        obj = debug_eval($', binding)
-        var_list(obj.instance_variables, obj.instance_eval{binding()})
-
-      when /^\s*c(?:onst(?:ant)?)?\s+/
-        obj = debug_eval($', binding)
-        unless obj.kind_of? Module
-          stdout.print "Should be Class/Module: ", $', "\n"
-        else
-          var_list(obj.constants, obj.module_eval{binding()})
-        end
-      end
-    end
-
-    def debug_method_info(input, binding)
-      case input
-      when /^i(:?nstance)?\s+/
-        obj = debug_eval($', binding)
-
-        len = 0
-        for v in obj.methods.sort
-          len += v.size + 1
-          if len > 70
-            len = v.size + 1
-            stdout.print "\n"
-          end
-          stdout.print v, " "
-        end
-        stdout.print "\n"
-
-      else
-        obj = debug_eval(input, binding)
-        unless obj.kind_of? Module
-          stdout.print "Should be Class/Module: ", input, "\n"
-        else
-          len = 0
-          for v in obj.instance_methods(false).sort
-            len += v.size + 1
-            if len > 70
-              len = v.size + 1
-              stdout.print "\n"
-            end
-            stdout.print v, " "
-          end
-          stdout.print "\n"
-        end
-      end
-    end
-
-    def thnum
-      num = DEBUGGER__.instance_eval{@thread_list[Thread.current]}
-      unless num
-        DEBUGGER__.make_thread_list
-        num = DEBUGGER__.instance_eval{@thread_list[Thread.current]}
-      end
-      num
-    end
-
-    def debug_command(file, line, id, binding)
-      MUTEX.lock
-      unless defined?($debugger_restart) and $debugger_restart
-        callcc{|c| $debugger_restart = c}
-      end
-      set_last_thread(Thread.current)
-      frame_pos = 0
-      binding_file = file
-      binding_line = line
-      previous_line = nil
-      if ENV['EMACS']
-        stdout.printf "\032\032%s:%d:\n", binding_file, binding_line
-      else
-        stdout.printf "%s:%d:%s", binding_file, binding_line,
-          line_at(binding_file, binding_line)
-      end
-      @frames[0] = [binding, file, line, id]
-      display_expressions(binding)
-      prompt = true
-      while prompt and input = readline("(rdb:%d) "%thnum(), true)
-        catch(:debug_error) do
-          if input == ""
-            next unless DEBUG_LAST_CMD[0]
-            input = DEBUG_LAST_CMD[0]
-            stdout.print input, "\n"
-          else
-            DEBUG_LAST_CMD[0] = input
-          end
-
-          case input
-          when /^\s*tr(?:ace)?(?:\s+(on|off))?(?:\s+(all))?$/
-            if defined?( $2 )
-              if $1 == 'on'
-                set_trace_all true
-              else
-                set_trace_all false
-              end
-            elsif defined?( $1 )
-              if $1 == 'on'
-                set_trace true
-              else
-                set_trace false
-              end
-            end
-            if trace?
-              stdout.print "Trace on.\n"
-            else
-              stdout.print "Trace off.\n"
-            end
-
-          when /^\s*b(?:reak)?\s+(?:(.+):)?([^.:]+)$/
-            pos = $2
-            if $1
-              klass = debug_silent_eval($1, binding)
-              file = $1
-            end
-            if pos =~ /^\d+$/
-              pname = pos
-              pos = pos.to_i
-            else
-              pname = pos = pos.intern.id2name
-            end
-            break_points.push [true, 0, klass || file, pos]
-            stdout.printf "Set breakpoint %d at %s:%s\n", break_points.size, klass || file, pname
-
-          when /^\s*b(?:reak)?\s+(.+)[#.]([^.:]+)$/
-            pos = $2.intern.id2name
-            klass = debug_eval($1, binding)
-            break_points.push [true, 0, klass, pos]
-            stdout.printf "Set breakpoint %d at %s.%s\n", break_points.size, klass, pos
-
-          when /^\s*wat(?:ch)?\s+(.+)$/
-            exp = $1
-            break_points.push [true, 1, exp]
-            stdout.printf "Set watchpoint %d:%s\n", break_points.size, exp
-
-          when /^\s*b(?:reak)?$/
-            if break_points.find{|b| b[1] == 0}
-              n = 1
-              stdout.print "Breakpoints:\n"
-              break_points.each do |b|
-                if b[0] and b[1] == 0
-                  stdout.printf "  %d %s:%s\n", n, b[2], b[3]
-                end
-                n += 1
-              end
-            end
-            if break_points.find{|b| b[1] == 1}
-              n = 1
-              stdout.print "\n"
-              stdout.print "Watchpoints:\n"
-              for b in break_points
-                if b[0] and b[1] == 1
-                  stdout.printf "  %d %s\n", n, b[2]
-                end
-                n += 1
-              end
-            end
-            if break_points.size == 0
-              stdout.print "No breakpoints\n"
-            else
-              stdout.print "\n"
-            end
-
-          when /^\s*del(?:ete)?(?:\s+(\d+))?$/
-            pos = $1
-            unless pos
-              input = readline("Clear all breakpoints? (y/n) ", false)
-              if input == "y"
-                for b in break_points
-                  b[0] = false
-                end
-              end
-            else
-              pos = pos.to_i
-              if break_points[pos-1]
-                break_points[pos-1][0] = false
-              else
-                stdout.printf "Breakpoint %d is not defined\n", pos
-              end
-            end
-
-          when /^\s*disp(?:lay)?\s+(.+)$/
-            exp = $1
-            display.push [true, exp]
-            stdout.printf "%d: ", display.size
-            display_expression(exp, binding)
-
-          when /^\s*disp(?:lay)?$/
-            display_expressions(binding)
-
-          when /^\s*undisp(?:lay)?(?:\s+(\d+))?$/
-            pos = $1
-            unless pos
-              input = readline("Clear all expressions? (y/n) ", false)
-              if input == "y"
-                for d in display
-                  d[0] = false
-                end
-              end
-            else
-              pos = pos.to_i
-              if display[pos-1]
-                display[pos-1][0] = false
-              else
-                stdout.printf "Display expression %d is not defined\n", pos
-              end
-            end
-
-          when /^\s*c(?:ont)?$/
-            prompt = false
-
-          when /^\s*s(?:tep)?(?:\s+(\d+))?$/
-            if $1
-              lev = $1.to_i
-            else
-              lev = 1
-            end
-            @stop_next = lev
-            prompt = false
-
-          when /^\s*n(?:ext)?(?:\s+(\d+))?$/
-            if $1
-              lev = $1.to_i
-            else
-              lev = 1
-            end
-            @stop_next = lev
-            @no_step = @frames.size - frame_pos
-            prompt = false
-
-          when /^\s*w(?:here)?$/, /^\s*f(?:rame)?$/
-            display_frames(frame_pos)
-
-          when /^\s*l(?:ist)?(?:\s+(.+))?$/
-            if not $1
-              b = previous_line ? previous_line + 10 : binding_line - 5
-              e = b + 9
-            elsif $1 == '-'
-              b = previous_line ? previous_line - 10 : binding_line - 5
-              e = b + 9
-            else
-              b, e = $1.split(/[-,]/)
-              if e
-                b = b.to_i
-                e = e.to_i
-              else
-                b = b.to_i - 5
-                e = b + 9
-              end
-            end
-            previous_line = b
-            display_list(b, e, binding_file, binding_line)
-
-          when /^\s*up(?:\s+(\d+))?$/
-            previous_line = nil
-            if $1
-              lev = $1.to_i
-            else
-              lev = 1
-            end
-            frame_pos += lev
-            if frame_pos >= @frames.size
-              frame_pos = @frames.size - 1
-              stdout.print "At toplevel\n"
-            end
-            binding, binding_file, binding_line = @frames[frame_pos]
-            stdout.print format_frame(frame_pos)
-
-          when /^\s*down(?:\s+(\d+))?$/
-            previous_line = nil
-            if $1
-              lev = $1.to_i
-            else
-              lev = 1
-            end
-            frame_pos -= lev
-            if frame_pos < 0
-              frame_pos = 0
-              stdout.print "At stack bottom\n"
-            end
-            binding, binding_file, binding_line = @frames[frame_pos]
-            stdout.print format_frame(frame_pos)
-
-          when /^\s*fin(?:ish)?$/
-            if frame_pos == @frames.size
-              stdout.print "\"finish\" not meaningful in the outermost frame.\n"
-            else
-              @finish_pos = @frames.size - frame_pos
-              frame_pos = 0
-              prompt = false
-            end
-
-          when /^\s*cat(?:ch)?(?:\s+(.+))?$/
-            if $1
-              excn = $1
-              if excn == 'off'
-                @catch = nil
-                stdout.print "Clear catchpoint.\n"
-              else
-                @catch = excn
-                stdout.printf "Set catchpoint %s.\n", @catch
-              end
-            else
-              if @catch
-                stdout.printf "Catchpoint %s.\n", @catch
-              else
-                stdout.print "No catchpoint.\n"
-              end
-            end
-
-          when /^\s*q(?:uit)?$/
-            input = readline("Really quit? (y/n) ", false)
-            if input == "y"
-              exit!  # exit -> exit!: No graceful way to stop threads...
-            end
-
-          when /^\s*v(?:ar)?\s+/
-            debug_variable_info($', binding)
-
-          when /^\s*m(?:ethod)?\s+/
-            debug_method_info($', binding)
-
-          when /^\s*th(?:read)?\s+/
-            if DEBUGGER__.debug_thread_info($', binding) == :cont
-              prompt = false
-            end
-
-          when /^\s*pp\s+/
-            PP.pp(debug_eval($', binding), stdout)
-
-          when /^\s*p\s+/
-            stdout.printf "%s\n", debug_eval($', binding).inspect
-
-          when /^\s*r(?:estart)?$/
-            $debugger_restart.call
-
-          when /^\s*h(?:elp)?$/
-            debug_print_help()
-
-          else
-            v = debug_eval(input, binding)
-            stdout.printf "%s\n", v.inspect
-          end
-        end
-      end
-      MUTEX.unlock
-      resume_all
-    end
-
-    def debug_print_help
-      stdout.print <<EOHELP
-Debugger help v.-0.002b
-Commands
-  b[reak] [file:|class:]<line|method>
-  b[reak] [class.]<line|method>
-                             set breakpoint to some position
-  wat[ch] <expression>       set watchpoint to some expression
-  cat[ch] (<exception>|off)  set catchpoint to an exception
-  b[reak]                    list breakpoints
-  cat[ch]                    show catchpoint
-  del[ete][ nnn]             delete some or all breakpoints
-  disp[lay] <expression>     add expression into display expression list
-  undisp[lay][ nnn]          delete one particular or all display expressions
-  c[ont]                     run until program ends or hit breakpoint
-  s[tep][ nnn]               step (into methods) one line or till line nnn
-  n[ext][ nnn]               go over one line or till line nnn
-  w[here]                    display frames
-  f[rame]                    alias for where
-  l[ist][ (-|nn-mm)]         list program, - lists backwards
-                             nn-mm lists given lines
-  up[ nn]                    move to higher frame
-  down[ nn]                  move to lower frame
-  fin[ish]                   return to outer frame
-  tr[ace] (on|off)           set trace mode of current thread
-  tr[ace] (on|off) all       set trace mode of all threads
-  q[uit]                     exit from debugger
-  v[ar] g[lobal]             show global variables
-  v[ar] l[ocal]              show local variables
-  v[ar] i[nstance] <object>  show instance variables of object
-  v[ar] c[onst] <object>     show constants of object
-  m[ethod] i[nstance] <obj>  show methods of object
-  m[ethod] <class|module>    show instance methods of class or module
-  th[read] l[ist]            list all threads
-  th[read] c[ur[rent]]       show current thread
-  th[read] [sw[itch]] <nnn>  switch thread context to nnn
-  th[read] stop <nnn>        stop thread nnn
-  th[read] resume <nnn>      resume thread nnn
-  p expression               evaluate expression and print its value
-  h[elp]                     print this help
-  <everything else>          evaluate
-EOHELP
-    end
-
-    def display_expressions(binding)
-      n = 1
-      for d in display
-        if d[0]
-          stdout.printf "%d: ", n
-          display_expression(d[1], binding)
-        end
-        n += 1
-      end
-    end
-
-    def display_expression(exp, binding)
-      stdout.printf "%s = %s\n", exp, debug_silent_eval(exp, binding).to_s
-    end
-
-    def frame_set_pos(file, line)
-      if @frames[0]
-        @frames[0][1] = file
-        @frames[0][2] = line
-      end
-    end
-
-    def display_frames(pos)
-      0.upto(@frames.size - 1) do |n|
-        if n == pos
-          stdout.print "--> "
-        else
-          stdout.print "    "
-        end
-        stdout.print format_frame(n)
-      end
-    end
-
-    def format_frame(pos)
-      _, file, line, id = @frames[pos]
-      sprintf "#%d %s:%s%s\n", pos + 1, file, line,
-        (id ? ":in `#{id.id2name}'" : "")
-    end
-
-    def display_list(b, e, file, line)
-      stdout.printf "[%d, %d] in %s\n", b, e, file
-      if lines = SCRIPT_LINES__[file] and lines != true
-        b.upto(e) do |n|
-          if n > 0 && lines[n-1]
-            if n == line
-              stdout.printf "=> %d  %s\n", n, lines[n-1].chomp
-            else
-              stdout.printf "   %d  %s\n", n, lines[n-1].chomp
-            end
-          end
-        end
-      else
-        stdout.printf "No sourcefile available for %s\n", file
-      end
-    end
-
-    def line_at(file, line)
-      lines = SCRIPT_LINES__[file]
-      if lines
-        return "\n" if lines == true
-        line = lines[line-1]
-        return "\n" unless line
-        return line
-      end
-      return "\n"
-    end
-
-    def debug_funcname(id)
-      if id.nil?
-        "toplevel"
-      else
-        id.id2name
-      end
-    end
-
-    def check_break_points(file, klass, pos, binding, id)
-      return false if break_points.empty?
-      n = 1
-      for b in break_points
-        if b[0]           # valid
-          if b[1] == 0    # breakpoint
-            if (b[2] == file and b[3] == pos) or
-                (klass and b[2] == klass and b[3] == pos)
-              stdout.printf "Breakpoint %d, %s at %s:%s\n", n, debug_funcname(id), file, pos
-              return true
-            end
-          elsif b[1] == 1 # watchpoint
-            if debug_silent_eval(b[2], binding)
-              stdout.printf "Watchpoint %d, %s at %s:%s\n", n, debug_funcname(id), file, pos
-              return true
-            end
-          end
-        end
-        n += 1
-      end
-      return false
-    end
-
-    def excn_handle(file, line, id, binding)
-      if $!.class <= SystemExit
-        set_trace_func nil
-        exit
-      end
-
-      if @catch and ($!.class.ancestors.find { |e| e.to_s == @catch })
-        stdout.printf "%s:%d: `%s' (%s)\n", file, line, $!, $!.class
-        fs = @frames.size
-        tb = caller(0)[-fs..-1]
-        if tb
-          for i in tb
-            stdout.printf "\tfrom %s\n", i
-          end
-        end
-        suspend_all
-        debug_command(file, line, id, binding)
-      end
-    end
-
-    def trace_func(event, file, line, id, binding, klass)
-      Tracer.trace_func(event, file, line, id, binding, klass) if trace?
-      context(Thread.current).check_suspend
-      @file = file
-      @line = line
-      case event
-      when 'line'
-        frame_set_pos(file, line)
-        if !@no_step or @frames.size == @no_step
-          @stop_next -= 1
-          @stop_next = -1 if @stop_next < 0
-        elsif @frames.size < @no_step
-          @stop_next = 0          # break here before leaving...
-        else
-          # nothing to do. skipped.
-        end
-        if @stop_next == 0 or check_break_points(file, nil, line, binding, id)
-          @no_step = nil
-          suspend_all
-          debug_command(file, line, id, binding)
-        end
-
-      when 'call'
-        @frames.unshift [binding, file, line, id]
-        if check_break_points(file, klass, id.id2name, binding, id)
-          suspend_all
-          debug_command(file, line, id, binding)
-        end
-
-      when 'c-call'
-        frame_set_pos(file, line)
-
-      when 'class'
-        @frames.unshift [binding, file, line, id]
-
-      when 'return', 'end'
-        if @frames.size == @finish_pos
-          @stop_next = 1
-          @finish_pos = 0
-        end
-        @frames.shift
-
-      when 'raise'
-        excn_handle(file, line, id, binding)
-
-      end
-      @last_file = file
-    end
-  end
-
-  trap("INT") { DEBUGGER__.interrupt }
-  @last_thread = Thread::main
-  @max_thread = 1
-  @thread_list = {Thread::main => 1}
-  @break_points = []
-  @display = []
-  @waiting = []
-  @stdout = STDOUT
-
-  class << DEBUGGER__
-    def stdout
-      @stdout
-    end
-
-    def stdout=(s)
-      @stdout = s
-    end
-
-    def display
-      @display
-    end
-
-    def break_points
-      @break_points
-    end
-
-    def waiting
-      @waiting
-    end
-
-    def set_trace( arg )
-      MUTEX.synchronize do
-        make_thread_list
-        for th, in @thread_list
-          context(th).set_trace arg
-        end
-      end
-      arg
-    end
-
-    def set_last_thread(th)
-      @last_thread = th
-    end
-
-    def suspend
-      MUTEX.synchronize do
-        make_thread_list
-        for th, in @thread_list
-          next if th == Thread.current
-          context(th).set_suspend
-        end
-      end
-      # Schedule other threads to suspend as soon as possible.
-      Thread.pass
-    end
-
-    def resume
-      MUTEX.synchronize do
-        make_thread_list
-        @thread_list.each do |th,|
-          next if th == Thread.current
-          context(th).clear_suspend
-        end
-        waiting.each do |th|
-          th.run
-        end
-        waiting.clear
-      end
-      # Schedule other threads to restart as soon as possible.
-      Thread.pass
-    end
-
-    def context(thread=Thread.current)
-      c = thread[:__debugger_data__]
-      unless c
-        thread[:__debugger_data__] = c = Context.new
-      end
-      c
-    end
-
-    def interrupt
-      context(@last_thread).stop_next
-    end
-
-    def get_thread(num)
-      th = @thread_list.key(num)
-      unless th
-        @stdout.print "No thread ##{num}\n"
-        throw :debug_error
-      end
-      th
-    end
-
-    def thread_list(num)
-      th = get_thread(num)
-      if th == Thread.current
-        @stdout.print "+"
-      else
-        @stdout.print " "
-      end
-      @stdout.printf "%d ", num
-      @stdout.print th.inspect, "\t"
-      file = context(th).instance_eval{@file}
-      if file
-        @stdout.print file,":",context(th).instance_eval{@line}
-      end
-      @stdout.print "\n"
-    end
-
-    def thread_list_all
-      for th in @thread_list.values.sort
-        thread_list(th)
-      end
-    end
-
-    def make_thread_list
-      hash = {}
-      for th in Thread::list
-        if @thread_list.key? th
-          hash[th] = @thread_list[th]
-        else
-          @max_thread += 1
-          hash[th] = @max_thread
-        end
-      end
-      @thread_list = hash
-    end
-
-    def debug_thread_info(input, binding)
-      case input
-      when /^l(?:ist)?/
-        make_thread_list
-        thread_list_all
-
-      when /^c(?:ur(?:rent)?)?$/
-        make_thread_list
-        thread_list(@thread_list[Thread.current])
-
-      when /^(?:sw(?:itch)?\s+)?(\d+)/
-        make_thread_list
-        th = get_thread($1.to_i)
-        if th == Thread.current
-          @stdout.print "It's the current thread.\n"
-        else
-          thread_list(@thread_list[th])
-          context(th).stop_next
-          th.run
-          return :cont
-        end
-
-      when /^stop\s+(\d+)/
-        make_thread_list
-        th = get_thread($1.to_i)
-        if th == Thread.current
-          @stdout.print "It's the current thread.\n"
-        elsif th.stop?
-          @stdout.print "Already stopped.\n"
-        else
-          thread_list(@thread_list[th])
-          context(th).suspend
-        end
-
-      when /^resume\s+(\d+)/
-        make_thread_list
-        th = get_thread($1.to_i)
-        if th == Thread.current
-          @stdout.print "It's the current thread.\n"
-        elsif !th.stop?
-          @stdout.print "Already running."
-        else
-          thread_list(@thread_list[th])
-          th.run
-        end
-      end
-    end
-  end
-
-  stdout.printf "Debug.rb\n"
-  stdout.printf "Emacs support available.\n\n"
-  RubyVM::InstructionSequence.compile_option = {
-    trace_instruction: true
-  }
-  set_trace_func proc { |event, file, line, id, binding, klass, *rest|
-    DEBUGGER__.context.trace_func event, file, line, id, binding, klass
-  }
-end
diff --git a/lib/delegate.gemspec b/lib/delegate.gemspec
new file mode 100644
index 0000000000..f7fcc1ceb9
--- /dev/null
+++ b/lib/delegate.gemspec
@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+name = File.basename(__FILE__, ".gemspec")
+version = ["lib", Array.new(name.count("-")+1, ".").join("/")].find do |dir|
+  break File.foreach(File.join(__dir__, dir, "#{name.tr('-', '/')}.rb")) do |line|
+    /^\s*VERSION\s*=\s*"(.*)"/ =~ line and break $1
+  end rescue nil
+end
+
+Gem::Specification.new do |spec|
+  spec.name          = name
+  spec.version       = version
+  spec.authors       = ["Yukihiro Matsumoto"]
+  spec.email         = ["matz@ruby-lang.org"]
+
+  spec.summary       = %q{Provides three abilities to delegate method calls to an object.}
+  spec.description   = %q{Provides three abilities to delegate method calls to an object.}
+  spec.homepage      = "https://github.com/ruby/delegate"
+  spec.licenses      = ["Ruby", "BSD-2-Clause"]
+
+  spec.metadata["homepage_uri"] = spec.homepage
+  spec.metadata["source_code_uri"] = spec.homepage
+
+  spec.files         = Dir.chdir(File.expand_path('..', __FILE__)) do
+    `git ls-files -z 2>#{IO::NULL}`.split("\x0").reject { |f| f.match(%r{^(test|spec|features)/}) }
+  end
+  spec.require_paths = ["lib"]
+  spec.required_ruby_version = '>= 3.0'
+end
diff --git a/lib/delegate.rb b/lib/delegate.rb
index 2086a721f9..0ff9797bdb 100644
--- a/lib/delegate.rb
+++ b/lib/delegate.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # = delegate -- Support for the Delegation Pattern
 #
 # Documentation by James Edward Gray II and Gavin Sinclair
@@ -17,15 +18,12 @@
 # yourself needing this control, have a look at Forwardable which is also in
 # the standard library.  It may suit your needs better.)
 #
-# SimpleDelegator's implementation serves as a nice example if the use of
+# SimpleDelegator's implementation serves as a nice example of the use of
 # Delegator:
 #
-#   class SimpleDelegator < Delegator
-#     def initialize(obj)
-#       super                  # pass obj to Delegator constructor, required
-#       @delegate_sd_obj = obj # store obj for future use
-#     end
+#   require 'delegate'
 #
+#   class SimpleDelegator < Delegator
 #     def __getobj__
 #       @delegate_sd_obj # return object we are delegating to, required
 #     end
@@ -41,9 +39,19 @@
 # Be advised, RDoc will not detect delegated methods.
 #
 class Delegator < BasicObject
+  # The version string
+  VERSION = "0.6.1"
+
   kernel = ::Kernel.dup
   kernel.class_eval do
-    [:to_s,:inspect,:=~,:!~,:===,:<=>,:eql?,:hash].each do |m|
+    alias __raise__ raise
+    [:to_s, :inspect, :!~, :===, :<=>, :hash].each do |m|
+      undef_method m
+    end
+    private_instance_methods.each do |m|
+      if /\Ablock_given\?\z|\Aiterator\?\z|\A__.*__\z/ =~ m
+        next
+      end
       undef_method m
     end
   end
@@ -55,6 +63,12 @@ class Delegator < BasicObject
   end
   # :startdoc:
 
+  ##
+  # :method: raise
+  # Use #__raise__ if your Delegator does not have a object to delegate the
+  # #raise method call.
+  #
+
   #
   # Pass in the _obj_ to delegate method calls to.  All methods supported by
   # _obj_ will be delegated to.
@@ -64,41 +78,64 @@ class Delegator < BasicObject
   end
 
   #
-  # Handles the magic of delegation through \_\_getobj\_\_.
+  # Handles the magic of delegation through +__getobj__+.
   #
-  def method_missing(m, *args, &block)
-    target = self.__getobj__
-    begin
-      target.respond_to?(m) ? target.__send__(m, *args, &block) : super(m, *args, &block)
-    ensure
-      $@.delete_if {|t| %r"\A#{Regexp.quote(__FILE__)}:#{__LINE__-2}:"o =~ t} if $@
+  ruby2_keywords def method_missing(m, *args, &block)
+    r = true
+    target = self.__getobj__ {r = false}
+
+    if r && target_respond_to?(target, m, false)
+      target.__send__(m, *args, &block)
+    elsif ::Kernel.method_defined?(m) || ::Kernel.private_method_defined?(m)
+      ::Kernel.instance_method(m).bind_call(self, *args, &block)
+    else
+      super(m, *args, &block)
     end
   end
 
   #
   # Checks for a method provided by this the delegate object by forwarding the
-  # call through \_\_getobj\_\_.
+  # call through +__getobj__+.
   #
   def respond_to_missing?(m, include_private)
-    r = self.__getobj__.respond_to?(m, include_private)
-    if r && include_private && !self.__getobj__.respond_to?(m, false)
-      warn "#{caller(3)[0]}: delegator does not forward private method \##{m}"
+    r = true
+    target = self.__getobj__ {r = false}
+    r &&= target_respond_to?(target, m, include_private)
+    if r && include_private && !target_respond_to?(target, m, false)
+      warn "delegator does not forward private method \##{m}", uplevel: 3
       return false
     end
     r
   end
 
+  KERNEL_RESPOND_TO = ::Kernel.instance_method(:respond_to?) # :nodoc:
+  private_constant :KERNEL_RESPOND_TO
+
+  # Handle BasicObject instances
+  private def target_respond_to?(target, m, include_private)
+    case target
+    when Object
+      target.respond_to?(m, include_private)
+    else
+      if KERNEL_RESPOND_TO.bind_call(target, :respond_to?)
+        target.respond_to?(m, include_private)
+      else
+        KERNEL_RESPOND_TO.bind_call(target, m, include_private)
+      end
+    end
+  end
+
   #
   # Returns the methods available to this delegate object as the union
-  # of this object's and \_\_getobj\_\_ methods.
+  # of this object's and +__getobj__+ methods.
   #
-  def methods
-    __getobj__.methods | super
+  def methods(all=true)
+    __getobj__.methods(all) | super
   end
 
   #
   # Returns the methods available to this delegate object as the union
-  # of this object's and \_\_getobj\_\_ public methods.
+  # of this object's and +__getobj__+ public methods.
   #
   def public_methods(all=true)
     __getobj__.public_methods(all) | super
@@ -106,7 +143,7 @@ class Delegator < BasicObject
 
   #
   # Returns the methods available to this delegate object as the union
-  # of this object's and \_\_getobj\_\_ protected methods.
+  # of this object's and +__getobj__+ protected methods.
   #
   def protected_methods(all=true)
     __getobj__.protected_methods(all) | super
@@ -130,6 +167,17 @@ class Delegator < BasicObject
     __getobj__ != obj
   end
 
+  #
+  # Returns true if two objects are considered of equal value.
+  #
+  def eql?(obj)
+    return true if obj.equal?(self)
+    obj.eql?(__getobj__)
+  end
+
+  #
+  # Delegates ! to the +__getobj__+
+  #
   def !
     !__getobj__
   end
@@ -139,7 +187,7 @@ class Delegator < BasicObject
   # method calls are being delegated to.
   #
   def __getobj__
-    raise NotImplementedError, "need to define `__getobj__'"
+    __raise__ ::NotImplementedError, "need to define '__getobj__'"
   end
 
   #
@@ -147,17 +195,17 @@ class Delegator < BasicObject
   # to _obj_.
   #
   def __setobj__(obj)
-    raise NotImplementedError, "need to define `__setobj__'"
+    __raise__ ::NotImplementedError, "need to define '__setobj__'"
   end
 
   #
-  # Serialization support for the object returned by \_\_getobj\_\_.
+  # Serialization support for the object returned by +__getobj__+.
   #
   def marshal_dump
     ivars = instance_variables.reject {|var| /\A@delegate_/ =~ var}
     [
       :__v2__,
-      ivars, ivars.map{|var| instance_variable_get(var)},
+      ivars, ivars.map {|var| instance_variable_get(var)},
       __getobj__
     ]
   end
@@ -168,15 +216,15 @@ class Delegator < BasicObject
   def marshal_load(data)
     version, vars, values, obj = data
     if version == :__v2__
-      vars.each_with_index{|var, i| instance_variable_set(var, values[i])}
+      vars.each_with_index {|var, i| instance_variable_set(var, values[i])}
       __setobj__(obj)
     else
       __setobj__(data)
     end
   end
 
-  def initialize_clone(obj) # :nodoc:
-    self.__setobj__(obj.__getobj__.clone)
+  def initialize_clone(obj, freeze: nil) # :nodoc:
+    self.__setobj__(obj.__getobj__.clone(freeze: freeze))
   end
   def initialize_dup(obj) # :nodoc:
     self.__setobj__(obj.__getobj__.dup)
@@ -184,39 +232,16 @@ class Delegator < BasicObject
   private :initialize_clone, :initialize_dup
 
   ##
-  # :method: trust
-  # Trust both the object returned by \_\_getobj\_\_ and self.
-  #
-
-  ##
-  # :method: untrust
-  # Untrust both the object returned by \_\_getobj\_\_ and self.
-  #
-
-  ##
-  # :method: taint
-  # Taint both the object returned by \_\_getobj\_\_ and self.
-  #
-
-  ##
-  # :method: untaint
-  # Untaint both the object returned by \_\_getobj\_\_ and self.
-  #
-
-  ##
   # :method: freeze
-  # Freeze both the object returned by \_\_getobj\_\_ and self.
+  # Freeze both the object returned by +__getobj__+ and self.
   #
-
-  [:trust, :untrust, :taint, :untaint, :freeze].each do |method|
-    define_method method do
-      __getobj__.send(method)
-      super()
-    end
+  def freeze
+    __getobj__.freeze
+    super()
   end
 
   @delegator_api = self.public_instance_methods
-  def self.public_api   # :nodoc:
+  def self.public_api # :nodoc:
     @delegator_api
   end
 end
@@ -227,6 +252,36 @@ end
 # and even to change the object being delegated to at a later time with
 # #__setobj__.
 #
+#   class User
+#     def born_on
+#       Date.new(1989, 9, 10)
+#     end
+#   end
+#
+#   require 'delegate'
+#
+#   class UserDecorator < SimpleDelegator
+#     def birth_year
+#       born_on.year
+#     end
+#   end
+#
+#   decorated_user = UserDecorator.new(User.new)
+#   decorated_user.birth_year  #=> 1989
+#   decorated_user.__getobj__  #=> #<User: ...>
+#
+# A SimpleDelegator instance can take advantage of the fact that SimpleDelegator
+# is a subclass of +Delegator+ to call <tt>super</tt> to have methods called on
+# the object being delegated to.
+#
+#   class SuperArray < SimpleDelegator
+#     def [](*args)
+#       super + 1
+#     end
+#   end
+#
+#   SuperArray.new([1])[0]  #=> 2
+#
 # Here's a simple example that takes advantage of the fact that
 # SimpleDelegator's delegation object can be changed at any time.
 #
@@ -259,9 +314,13 @@ end
 #    Non-Nil:  7
 #     Unique:  6
 #
-class SimpleDelegator<Delegator
+class SimpleDelegator < Delegator
   # Returns the current object method calls are being delegated to.
   def __getobj__
+    unless defined?(@delegate_sd_obj)
+      return yield if block_given?
+      __raise__ ::ArgumentError, "not delegated"
+    end
     @delegate_sd_obj
   end
 
@@ -280,24 +339,11 @@ class SimpleDelegator<Delegator
   #   puts names[1]    # => Sinclair
   #
   def __setobj__(obj)
-    raise ArgumentError, "cannot delegate to self" if self.equal?(obj)
+    __raise__ ::ArgumentError, "cannot delegate to self" if self.equal?(obj)
     @delegate_sd_obj = obj
   end
 end
 
-# :stopdoc:
-def Delegator.delegating_block(mid)
-  lambda do |*args, &block|
-    target = self.__getobj__
-    begin
-      target.__send__(mid, *args, &block)
-    ensure
-      $@.delete_if {|t| /\A#{Regexp.quote(__FILE__)}:#{__LINE__-2}:/o =~ t} if $@
-    end
-  end
-end
-# :startdoc:
-
 #
 # The primary interface to this library.  Use to setup delegation when defining
 # your class.
@@ -308,6 +354,14 @@ end
 #     end
 #   end
 #
+# or:
+#
+#   MyClass = DelegateClass(ClassToDelegateTo) do    # Step 1
+#     def initialize
+#       super(obj_of_ClassToDelegateTo)              # Step 2
+#     end
+#   end
+#
 # Here's a sample of use from Tempfile which is really a File object with a
 # few special rules about storage location and when the File should be
 # deleted.  That makes for an almost textbook perfect example of how to use
@@ -331,62 +385,79 @@ end
 #     # ...
 #   end
 #
-def DelegateClass(superclass)
+def DelegateClass(superclass, &block)
   klass = Class.new(Delegator)
-  methods = superclass.instance_methods
-  methods -= ::Delegator.public_api
-  methods -= [:to_s,:inspect,:=~,:!~,:===]
+  ignores = [*::Delegator.public_api, :to_s, :inspect, :=~, :!~, :===]
+  protected_instance_methods = superclass.protected_instance_methods
+  protected_instance_methods -= ignores
+  public_instance_methods = superclass.public_instance_methods
+  public_instance_methods -= ignores
+
+  methods_to_define =
+    public_instance_methods.map { |x| [x, false] } +
+    protected_instance_methods.map { |x| [x, true] }
+
+  source = []
+
+  methods_to_define.each do |target_name, is_protected|
+    unless target_name.match?(/\A[_a-zA-Z]\w*[!\?]?\z/)
+      placeholder_name = :__delegate
+    end
+
+    send_source =
+      if is_protected || placeholder_name
+        "__getobj__.__send__(#{target_name.inspect}, ...)"
+      else
+        "__getobj__.#{target_name}(...)"
+      end
+    source << "def #{placeholder_name || target_name}(...); #{send_source}; end"
+
+    if placeholder_name
+      source << "alias_method #{target_name.inspect}, :#{placeholder_name}"
+      source << "remove_method :#{placeholder_name}"
+    end
+  end
+
   klass.module_eval do
-    def __getobj__  # :nodoc:
+    def __getobj__ # :nodoc:
+      unless defined?(@delegate_dc_obj)
+        return yield if block_given?
+        __raise__ ::ArgumentError, "not delegated"
+      end
       @delegate_dc_obj
     end
+
     def __setobj__(obj)  # :nodoc:
-      raise ArgumentError, "cannot delegate to self" if self.equal?(obj)
+      __raise__ ::ArgumentError, "cannot delegate to self" if self.equal?(obj)
       @delegate_dc_obj = obj
     end
-    methods.each do |method|
-      define_method(method, Delegator.delegating_block(method))
-    end
+
+    class_eval(source.join(";"), __FILE__, __LINE__)
+
+    protected(*protected_instance_methods)
   end
+
   klass.define_singleton_method :public_instance_methods do |all=true|
-    super(all) - superclass.protected_instance_methods
+    super(all) | superclass.public_instance_methods
   end
   klass.define_singleton_method :protected_instance_methods do |all=true|
     super(all) | superclass.protected_instance_methods
   end
-  return klass
-end
-
-# :enddoc:
-
-if __FILE__ == $0
-  class ExtArray<DelegateClass(Array)
-    def initialize()
-      super([])
-    end
-  end
-
-  ary = ExtArray.new
-  p ary.class
-  ary.push 25
-  p ary
-  ary.push 42
-  ary.each {|x| p x}
-
-  foo = Object.new
-  def foo.test
-    25
+  klass.define_singleton_method :instance_methods do |all=true|
+    super(all) | superclass.instance_methods
   end
-  def foo.iter
-    yield self
+  klass.define_singleton_method :public_instance_method do |name|
+    super(name)
+  rescue NameError
+    raise unless self.public_instance_methods.include?(name)
+    superclass.public_instance_method(name)
   end
-  def foo.error
-    raise 'this is OK'
+  klass.define_singleton_method :instance_method do |name|
+    super(name)
+  rescue NameError
+    raise unless self.instance_methods.include?(name)
+    superclass.instance_method(name)
   end
-  foo2 = SimpleDelegator.new(foo)
-  p foo2
-  foo2.instance_eval{print "foo\n"}
-  p foo.test == foo2.test       # => true
-  p foo2.iter{[55,true]}        # => true
-  foo2.error                    # raise error!
+  klass.module_eval(&block) if block
+  return klass
 end
diff --git a/lib/did_you_mean.rb b/lib/did_you_mean.rb
new file mode 100644
index 0000000000..640d910389
--- /dev/null
+++ b/lib/did_you_mean.rb
@@ -0,0 +1,131 @@
+require_relative "did_you_mean/version"
+require_relative "did_you_mean/core_ext/name_error"
+
+require_relative "did_you_mean/spell_checker"
+require_relative 'did_you_mean/spell_checkers/name_error_checkers'
+require_relative 'did_you_mean/spell_checkers/method_name_checker'
+require_relative 'did_you_mean/spell_checkers/key_error_checker'
+require_relative 'did_you_mean/spell_checkers/null_checker'
+require_relative 'did_you_mean/spell_checkers/require_path_checker'
+require_relative 'did_you_mean/spell_checkers/pattern_key_name_checker'
+require_relative 'did_you_mean/formatter'
+require_relative 'did_you_mean/tree_spell_checker'
+
+# The +DidYouMean+ gem adds functionality to suggest possible method/class
+# names upon errors such as +NameError+ and +NoMethodError+. In Ruby 2.3 or
+# later, it is automatically activated during startup.
+#
+# @example
+#
+#   methosd
+#   # => NameError: undefined local variable or method `methosd' for main:Object
+#   #   Did you mean?  methods
+#   #                  method
+#
+#   OBject
+#   # => NameError: uninitialized constant OBject
+#   #    Did you mean?  Object
+#
+#   @full_name = "Yuki Nishijima"
+#   first_name, last_name = full_name.split(" ")
+#   # => NameError: undefined local variable or method `full_name' for main:Object
+#   #    Did you mean?  @full_name
+#
+#   @@full_name = "Yuki Nishijima"
+#   @@full_anme
+#   # => NameError: uninitialized class variable @@full_anme in Object
+#   #    Did you mean?  @@full_name
+#
+#   full_name = "Yuki Nishijima"
+#   full_name.starts_with?("Y")
+#   # => NoMethodError: undefined method `starts_with?' for "Yuki Nishijima":String
+#   #    Did you mean?  start_with?
+#
+#   hash = {foo: 1, bar: 2, baz: 3}
+#   hash.fetch(:fooo)
+#   # => KeyError: key not found: :fooo
+#   #    Did you mean?  :foo
+#
+#
+# == Disabling \DidYouMean
+#
+# Occasionally, you may want to disable the \DidYouMean gem for e.g.
+# debugging issues in the error object itself. You can disable it entirely by
+# specifying +--disable-did_you_mean+ option to the +ruby+ command:
+#
+#   $ ruby --disable-did_you_mean -e "1.zeor?"
+#   -e:1:in `<main>': undefined method `zeor?' for 1:Integer (NameError)
+#
+# When you do not have direct access to the +ruby+ command (e.g.
+# +rails console+, +irb+), you could applyoptions using the +RUBYOPT+
+# environment variable:
+#
+#   $ RUBYOPT='--disable-did_you_mean' irb
+#   irb:0> 1.zeor?
+#   # => NoMethodError (undefined method `zeor?' for 1:Integer)
+#
+#
+# == Getting the original error message
+#
+# Sometimes, you do not want to disable the gem entirely, but need to get the
+# original error message without suggestions (e.g. testing). In this case, you
+# could use the +#original_message+ method on the error object:
+#
+#   no_method_error = begin
+#                       1.zeor?
+#                     rescue NoMethodError => error
+#                       error
+#                     end
+#
+#   no_method_error.message
+#   # => NoMethodError (undefined method `zeor?' for 1:Integer)
+#   #    Did you mean?  zero?
+#
+#   no_method_error.original_message
+#   # => NoMethodError (undefined method `zeor?' for 1:Integer)
+#
+module DidYouMean
+  # Map of error types and spell checker objects.
+  @spell_checkers = Hash.new(NullChecker)
+
+  # Returns a sharable hash map of error types and spell checker objects.
+  def self.spell_checkers
+    @spell_checkers
+  end
+
+  # Adds +DidYouMean+ functionality to an error using a given spell checker
+  def self.correct_error(error_class, spell_checker)
+    if defined?(Ractor)
+      new_mapping = { **@spell_checkers, error_class.to_s => spell_checker }
+      new_mapping.default = NullChecker
+
+      @spell_checkers = Ractor.make_shareable(new_mapping)
+    else
+      spell_checkers[error_class.to_s] = spell_checker
+    end
+
+    error_class.prepend(Correctable) if error_class.is_a?(Class) && !(error_class < Correctable)
+  end
+
+  correct_error NameError, NameErrorCheckers
+  correct_error KeyError, KeyErrorChecker
+  correct_error NoMethodError, MethodNameChecker
+  correct_error LoadError, RequirePathChecker if RUBY_VERSION >= '2.8.0'
+  correct_error NoMatchingPatternKeyError, PatternKeyNameChecker if defined?(::NoMatchingPatternKeyError)
+
+  # Returns the currently set formatter. By default, it is set to +DidYouMean::Formatter+.
+  def self.formatter
+    if defined?(Ractor)
+      Ractor.current[:__did_you_mean_formatter__] || Formatter
+    else
+      Formatter
+    end
+  end
+
+  # Updates the primary formatter used to format the suggestions.
+  def self.formatter=(formatter)
+    if defined?(Ractor)
+      Ractor.current[:__did_you_mean_formatter__] = formatter
+    end
+  end
+end
diff --git a/lib/did_you_mean/core_ext/name_error.rb b/lib/did_you_mean/core_ext/name_error.rb
new file mode 100644
index 0000000000..8c170c4b90
--- /dev/null
+++ b/lib/did_you_mean/core_ext/name_error.rb
@@ -0,0 +1,57 @@
+module DidYouMean
+  module Correctable
+    if Exception.method_defined?(:detailed_message)
+      # just for compatibility
+      def original_message
+        # we cannot use alias here because
+        to_s
+      end
+
+      def detailed_message(highlight: true, did_you_mean: true, **)
+        msg = super.dup
+
+        return msg unless did_you_mean
+
+        suggestion = DidYouMean.formatter.message_for(corrections)
+
+        if highlight
+          suggestion = suggestion.gsub(/.+/) { "\e[1m" + $& + "\e[m" }
+        end
+
+        msg << suggestion
+        msg
+      rescue
+        super
+      end
+    else
+      SKIP_TO_S_FOR_SUPER_LOOKUP = true
+      private_constant :SKIP_TO_S_FOR_SUPER_LOOKUP
+
+      def original_message
+        meth = method(:to_s)
+        while meth.owner.const_defined?(:SKIP_TO_S_FOR_SUPER_LOOKUP)
+          meth = meth.super_method
+        end
+        meth.call
+      end
+
+      def to_s
+        msg = super.dup
+        suggestion = DidYouMean.formatter.message_for(corrections)
+
+        msg << suggestion if !msg.include?(suggestion)
+        msg
+      rescue
+        super
+      end
+    end
+
+    def corrections
+      @corrections ||= spell_checker.corrections
+    end
+
+    def spell_checker
+      DidYouMean.spell_checkers[self.class.to_s].new(self)
+    end
+  end
+end
diff --git a/lib/did_you_mean/did_you_mean.gemspec b/lib/did_you_mean/did_you_mean.gemspec
new file mode 100644
index 0000000000..be4ac76b4b
--- /dev/null
+++ b/lib/did_you_mean/did_you_mean.gemspec
@@ -0,0 +1,25 @@
+# coding: utf-8
+lib = File.expand_path('../lib', __FILE__)
+$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
+begin
+  require_relative "lib/did_you_mean/version"
+rescue LoadError # Fallback to load version file in ruby core repository
+  require_relative "version"
+end
+
+Gem::Specification.new do |spec|
+  spec.name          = "did_you_mean"
+  spec.version       = DidYouMean::VERSION
+  spec.authors       = ["Yuki Nishijima"]
+  spec.email         = ["mail@yukinishijima.net"]
+  spec.summary       = '"Did you mean?" experience in Ruby'
+  spec.description   = 'The gem that has been saving people from typos since 2014.'
+  spec.homepage      = "https://github.com/ruby/did_you_mean"
+  spec.license       = "MIT"
+
+  spec.files         = `git ls-files`.split($/).reject{|path| path.start_with?('evaluation/') }
+  spec.test_files    = spec.files.grep(%r{^(test)/})
+  spec.require_paths = ["lib"]
+
+  spec.required_ruby_version = '>= 2.5.0'
+end
diff --git a/lib/did_you_mean/experimental.rb b/lib/did_you_mean/experimental.rb
new file mode 100644
index 0000000000..f8e37e4532
--- /dev/null
+++ b/lib/did_you_mean/experimental.rb
@@ -0,0 +1,2 @@
+warn "Experimental features in the did_you_mean gem has been removed " \
+     "and `require \"did_you_mean/experimental\"' has no effect."
diff --git a/lib/did_you_mean/formatter.rb b/lib/did_you_mean/formatter.rb
new file mode 100644
index 0000000000..c43748f707
--- /dev/null
+++ b/lib/did_you_mean/formatter.rb
@@ -0,0 +1,44 @@
+# frozen-string-literal: true
+
+module DidYouMean
+  # The +DidYouMean::Formatter+ is the basic, default formatter for the
+  # gem. The formatter responds to the +message_for+ method and it returns a
+  # human readable string.
+  class Formatter
+
+    # Returns a human readable string that contains +corrections+. This
+    # formatter is designed to be less verbose to not take too much screen
+    # space while being helpful enough to the user.
+    #
+    # @example
+    #
+    #   formatter = DidYouMean::Formatter.new
+    #
+    #   # displays suggestions in two lines with the leading empty line
+    #   puts formatter.message_for(["methods", "method"])
+    #
+    #   Did you mean?  methods
+    #                   method
+    #   # => nil
+    #
+    #   # displays an empty line
+    #   puts formatter.message_for([])
+    #
+    #   # => nil
+    #
+    def self.message_for(corrections)
+      corrections.empty? ? "" : "\nDid you mean?  #{corrections.join("\n               ")}"
+    end
+
+    def message_for(corrections)
+      warn "The instance method #message_for has been deprecated. Please use the class method " \
+           "DidYouMean::Formatter.message_for(...) instead."
+
+      self.class.message_for(corrections)
+    end
+  end
+
+  PlainFormatter = Formatter
+
+  deprecate_constant :PlainFormatter
+end
diff --git a/lib/did_you_mean/formatters/plain_formatter.rb b/lib/did_you_mean/formatters/plain_formatter.rb
new file mode 100644
index 0000000000..d669588e0f
--- /dev/null
+++ b/lib/did_you_mean/formatters/plain_formatter.rb
@@ -0,0 +1,4 @@
+require_relative '../formatter'
+
+warn "`require 'did_you_mean/formatters/plain_formatter'` is deprecated. Please `require 'did_you_mean/formatter'` " \
+     "instead."
diff --git a/lib/did_you_mean/formatters/verbose_formatter.rb b/lib/did_you_mean/formatters/verbose_formatter.rb
new file mode 100644
index 0000000000..f6623681f2
--- /dev/null
+++ b/lib/did_you_mean/formatters/verbose_formatter.rb
@@ -0,0 +1,10 @@
+# frozen-string-literal: true
+
+warn "`require 'did_you_mean/formatters/verbose_formatter'` is deprecated and falls back to the default formatter. "
+
+require_relative '../formatter'
+
+module DidYouMean
+  # For compatibility:
+  VerboseFormatter = Formatter
+end
diff --git a/lib/did_you_mean/jaro_winkler.rb b/lib/did_you_mean/jaro_winkler.rb
new file mode 100644
index 0000000000..9a3e57f6d7
--- /dev/null
+++ b/lib/did_you_mean/jaro_winkler.rb
@@ -0,0 +1,84 @@
+module DidYouMean
+  module Jaro
+    module_function
+
+    def distance(str1, str2)
+      str1, str2 = str2, str1 if str1.length > str2.length
+      length1, length2 = str1.length, str2.length
+
+      m          = 0.0
+      t          = 0.0
+      range      = length2 > 3 ? length2 / 2 - 1 : 0
+      flags1     = 0
+      flags2     = 0
+
+      # Avoid duplicating enumerable objects
+      str1_codepoints = str1.codepoints
+      str2_codepoints = str2.codepoints
+
+      i = 0
+      while i < length1
+        last = i + range
+        j    = (i >= range) ? i - range : 0
+
+        while j <= last
+          if flags2[j] == 0 && str1_codepoints[i] == str2_codepoints[j]
+            flags2 |= (1 << j)
+            flags1 |= (1 << i)
+            m += 1
+            break
+          end
+
+          j += 1
+        end
+
+        i += 1
+      end
+
+      k = i = 0
+      while i < length1
+        if flags1[i] != 0
+          j = index = k
+
+          k = while j < length2
+            index = j
+            break(j + 1) if flags2[j] != 0
+
+            j += 1
+          end
+
+          t += 1 if str1_codepoints[i] != str2_codepoints[index]
+        end
+
+        i += 1
+      end
+      t = (t / 2).floor
+
+      m == 0 ? 0 : (m / length1 + m / length2 + (m - t) / m) / 3
+    end
+  end
+
+  module JaroWinkler
+    WEIGHT    = 0.1
+    THRESHOLD = 0.7
+
+    module_function
+
+    def distance(str1, str2)
+      jaro_distance = Jaro.distance(str1, str2)
+
+      if jaro_distance > THRESHOLD
+        codepoints2  = str2.codepoints
+        prefix_bonus = 0
+
+        str1.each_codepoint do |char1|
+          char1 == codepoints2[prefix_bonus] && prefix_bonus < 4 ? prefix_bonus += 1 : break
+        end
+
+        jaro_distance + (prefix_bonus * WEIGHT * (1 - jaro_distance))
+      else
+        jaro_distance
+      end
+    end
+  end
+end
diff --git a/lib/did_you_mean/levenshtein.rb b/lib/did_you_mean/levenshtein.rb
new file mode 100644
index 0000000000..098053470f
--- /dev/null
+++ b/lib/did_you_mean/levenshtein.rb
@@ -0,0 +1,57 @@
+module DidYouMean
+  module Levenshtein # :nodoc:
+    # This code is based directly on the Text gem implementation
+    # Copyright (c) 2006-2013 Paul Battley, Michael Neumann, Tim Fletcher.
+    #
+    # Returns a value representing the "cost" of transforming str1 into str2
+    def distance(str1, str2)
+      n = str1.length
+      m = str2.length
+      return m if n.zero?
+      return n if m.zero?
+
+      d = (0..m).to_a
+      x = nil
+
+      # to avoid duplicating an enumerable object, create it outside of the loop
+      str2_codepoints = str2.codepoints
+
+      str1.each_codepoint.with_index(1) do |char1, i|
+        j = 0
+        while j < m
+          cost = (char1 == str2_codepoints[j]) ? 0 : 1
+          x = min3(
+            d[j+1] + 1, # insertion
+            i + 1,      # deletion
+            d[j] + cost # substitution
+          )
+          d[j] = i
+          i = x
+
+          j += 1
+        end
+        d[m] = x
+      end
+
+      x
+    end
+    module_function :distance
+
+    private
+
+    # detects the minimum value out of three arguments. This method is
+    # faster than `[a, b, c].min` and puts less GC pressure.
+    # See https://github.com/ruby/did_you_mean/pull/1 for a performance
+    # benchmark.
+    def min3(a, b, c)
+      if a < b && a < c
+        a
+      elsif b < c
+        b
+      else
+        c
+      end
+    end
+    module_function :min3
+  end
+end
diff --git a/lib/did_you_mean/spell_checker.rb b/lib/did_you_mean/spell_checker.rb
new file mode 100644
index 0000000000..37da2fc7a6
--- /dev/null
+++ b/lib/did_you_mean/spell_checker.rb
@@ -0,0 +1,46 @@
+# frozen-string-literal: true
+
+require_relative "levenshtein"
+require_relative "jaro_winkler"
+
+module DidYouMean
+  class SpellChecker
+    def initialize(dictionary:)
+      @dictionary = dictionary
+    end
+
+    def correct(input)
+      normalized_input = normalize(input)
+      threshold = normalized_input.length > 3 ? 0.834 : 0.77
+
+      words = @dictionary.select { |word| JaroWinkler.distance(normalize(word), normalized_input) >= threshold }
+      words.reject! { |word| input.to_s == word.to_s }
+      words.sort_by! { |word| JaroWinkler.distance(word.to_s, normalized_input) }
+      words.reverse!
+
+      # Correct mistypes
+      threshold   = (normalized_input.length * 0.25).ceil
+      corrections = words.select { |c| Levenshtein.distance(normalize(c), normalized_input) <= threshold }
+
+      # Correct misspells
+      if corrections.empty?
+        corrections = words.select do |word|
+          word   = normalize(word)
+          length = normalized_input.length < word.length ? normalized_input.length : word.length
+
+          Levenshtein.distance(word, normalized_input) < length
+        end.first(1)
+      end
+
+      corrections
+    end
+
+    private
+
+    def normalize(str_or_symbol) #:nodoc:
+      str = str_or_symbol.to_s.downcase
+      str.tr!("@", "")
+      str
+    end
+  end
+end
diff --git a/lib/did_you_mean/spell_checkers/key_error_checker.rb b/lib/did_you_mean/spell_checkers/key_error_checker.rb
new file mode 100644
index 0000000000..955bff1be6
--- /dev/null
+++ b/lib/did_you_mean/spell_checkers/key_error_checker.rb
@@ -0,0 +1,28 @@
+require_relative "../spell_checker"
+
+module DidYouMean
+  class KeyErrorChecker
+    def initialize(key_error)
+      @key = key_error.key
+      @keys = key_error.receiver.keys
+    end
+
+    def corrections
+      @corrections ||= exact_matches.empty? ? SpellChecker.new(dictionary: @keys).correct(@key).map(&:inspect) : exact_matches
+    end
+
+    private
+
+    def exact_matches
+      @exact_matches ||= @keys.select { |word| @key == word.to_s }.map { |obj| format_object(obj) }
+    end
+
+    def format_object(symbol_or_object)
+      if symbol_or_object.is_a?(Symbol)
+        ":#{symbol_or_object}"
+      else
+        symbol_or_object.to_s
+      end
+    end
+  end
+end
diff --git a/lib/did_you_mean/spell_checkers/method_name_checker.rb b/lib/did_you_mean/spell_checkers/method_name_checker.rb
new file mode 100644
index 0000000000..b5cbbb5da6
--- /dev/null
+++ b/lib/did_you_mean/spell_checkers/method_name_checker.rb
@@ -0,0 +1,79 @@
+require_relative "../spell_checker"
+
+module DidYouMean
+  class MethodNameChecker
+    attr_reader :method_name, :receiver
+
+    NAMES_TO_EXCLUDE = { NilClass => nil.methods }
+    NAMES_TO_EXCLUDE.default = []
+    Ractor.make_shareable(NAMES_TO_EXCLUDE) if defined?(Ractor)
+
+    # +MethodNameChecker::RB_RESERVED_WORDS+ is the list of reserved words in
+    # Ruby that take an argument. Unlike
+    # +VariableNameChecker::RB_RESERVED_WORDS+, these reserved words require
+    # an argument, and a +NoMethodError+ is raised due to the presence of the
+    # argument.
+    #
+    # The +MethodNameChecker+ will use this list to suggest a reversed word if
+    # a +NoMethodError+ is raised and found closest matches.
+    #
+    # Also see +VariableNameChecker::RB_RESERVED_WORDS+.
+    RB_RESERVED_WORDS = %i(
+      alias
+      case
+      def
+      defined?
+      elsif
+      end
+      ensure
+      for
+      rescue
+      super
+      undef
+      unless
+      until
+      when
+      while
+      yield
+    )
+
+    Ractor.make_shareable(RB_RESERVED_WORDS) if defined?(Ractor)
+
+    def initialize(exception)
+      @method_name  = exception.name
+      @receiver     = exception.receiver
+      @private_call = exception.respond_to?(:private_call?) ? exception.private_call? : false
+    end
+
+    def corrections
+      @corrections ||= begin
+                         dictionary = method_names
+                         dictionary = RB_RESERVED_WORDS + dictionary if @private_call
+
+                         SpellChecker.new(dictionary: dictionary).correct(method_name) - names_to_exclude
+                       end
+    end
+
+    def method_names
+      if Object === receiver
+        method_names = receiver.methods + receiver.singleton_methods
+        method_names += receiver.private_methods if @private_call
+        method_names.uniq!
+        # Assume that people trying to use a writer are not interested in a reader
+        # and vice versa
+        if method_name.match?(/=\Z/)
+          method_names.select! { |name| name.match?(/=\Z/) }
+        else
+          method_names.reject! { |name| name.match?(/=\Z/) }
+        end
+        method_names
+      else
+        []
+      end
+    end
+
+    def names_to_exclude
+      Object === receiver ? NAMES_TO_EXCLUDE[receiver.class] : []
+    end
+  end
+end
diff --git a/lib/did_you_mean/spell_checkers/name_error_checkers.rb b/lib/did_you_mean/spell_checkers/name_error_checkers.rb
new file mode 100644
index 0000000000..6e2aaa4cb1
--- /dev/null
+++ b/lib/did_you_mean/spell_checkers/name_error_checkers.rb
@@ -0,0 +1,20 @@
+require_relative 'name_error_checkers/class_name_checker'
+require_relative 'name_error_checkers/variable_name_checker'
+
+module DidYouMean
+  class << (NameErrorCheckers = Object.new)
+    def new(exception)
+      case exception.original_message
+      when /uninitialized constant/
+        ClassNameChecker
+      when /undefined local variable or method/,
+           /undefined method/,
+           /uninitialized class variable/,
+           /no member '.*' in struct/
+        VariableNameChecker
+      else
+        NullChecker
+      end.new(exception)
+    end
+  end
+end
diff --git a/lib/did_you_mean/spell_checkers/name_error_checkers/class_name_checker.rb b/lib/did_you_mean/spell_checkers/name_error_checkers/class_name_checker.rb
new file mode 100644
index 0000000000..924265b929
--- /dev/null
+++ b/lib/did_you_mean/spell_checkers/name_error_checkers/class_name_checker.rb
@@ -0,0 +1,49 @@
+# frozen-string-literal: true
+
+require_relative "../../spell_checker"
+
+module DidYouMean
+  class ClassNameChecker
+    attr_reader :class_name
+
+    def initialize(exception)
+      @class_name, @receiver, @original_message = exception.name, exception.receiver, exception.original_message
+    end
+
+    def corrections
+      @corrections ||= SpellChecker.new(dictionary: class_names)
+                         .correct(class_name)
+                         .map(&:full_name)
+                         .reject {|qualified_name| @original_message.include?(qualified_name) }
+    end
+
+    def class_names
+      scopes.flat_map do |scope|
+        scope.constants.map do |c|
+          ClassName.new(c, scope == Object ? "" : "#{scope}::")
+        end
+      end
+    end
+
+    def scopes
+      @scopes ||= @receiver.to_s.split("::").inject([Object]) do |_scopes, scope|
+        _scopes << _scopes.last.const_get(scope)
+      end.uniq
+    end
+
+    class ClassName < String
+      attr :namespace
+
+      def initialize(name, namespace = '')
+        super(name.to_s)
+        @namespace = namespace
+      end
+
+      def full_name
+        self.class.new("#{namespace}#{self}")
+      end
+    end
+
+    private_constant :ClassName
+  end
+end
diff --git a/lib/did_you_mean/spell_checkers/name_error_checkers/variable_name_checker.rb b/lib/did_you_mean/spell_checkers/name_error_checkers/variable_name_checker.rb
new file mode 100644
index 0000000000..9a6e04fe64
--- /dev/null
+++ b/lib/did_you_mean/spell_checkers/name_error_checkers/variable_name_checker.rb
@@ -0,0 +1,85 @@
+# frozen-string-literal: true
+
+require_relative "../../spell_checker"
+
+module DidYouMean
+  class VariableNameChecker
+    attr_reader :name, :method_names, :lvar_names, :ivar_names, :cvar_names
+
+    NAMES_TO_EXCLUDE = { 'foo' => [:fork, :for] }
+    NAMES_TO_EXCLUDE.default = []
+    Ractor.make_shareable(NAMES_TO_EXCLUDE) if defined?(Ractor)
+
+    # +VariableNameChecker::RB_RESERVED_WORDS+ is the list of all reserved
+    # words in Ruby. They could be declared like methods are, and a typo would
+    # cause Ruby to raise a +NameError+ because of the way they are declared.
+    #
+    # The +:VariableNameChecker+ will use this list to suggest a reversed word
+    # if a +NameError+ is raised and found closest matches, excluding:
+    #
+    #   * +do+
+    #   * +if+
+    #   * +in+
+    #   * +or+
+    #
+    # Also see +MethodNameChecker::RB_RESERVED_WORDS+.
+    RB_RESERVED_WORDS = %i(
+      BEGIN
+      END
+      alias
+      and
+      begin
+      break
+      case
+      class
+      def
+      defined?
+      else
+      elsif
+      end
+      ensure
+      false
+      for
+      module
+      next
+      nil
+      not
+      redo
+      rescue
+      retry
+      return
+      self
+      super
+      then
+      true
+      undef
+      unless
+      until
+      when
+      while
+      yield
+      __LINE__
+      __FILE__
+      __ENCODING__
+    )
+
+    Ractor.make_shareable(RB_RESERVED_WORDS) if defined?(Ractor)
+
+    def initialize(exception)
+      @name       = exception.name.to_s.tr("@", "")
+      @lvar_names = exception.respond_to?(:local_variables) ? exception.local_variables : []
+      receiver    = exception.receiver
+
+      @method_names = receiver.methods + receiver.private_methods
+      @ivar_names   = receiver.instance_variables
+      @cvar_names   = receiver.class.class_variables
+      @cvar_names  += receiver.class_variables if receiver.kind_of?(Module)
+    end
+
+    def corrections
+      @corrections ||= SpellChecker
+                     .new(dictionary: (RB_RESERVED_WORDS + lvar_names + method_names + ivar_names + cvar_names))
+                     .correct(name).uniq - NAMES_TO_EXCLUDE[@name]
+    end
+  end
+end
diff --git a/lib/did_you_mean/spell_checkers/null_checker.rb b/lib/did_you_mean/spell_checkers/null_checker.rb
new file mode 100644
index 0000000000..1306f69d4a
--- /dev/null
+++ b/lib/did_you_mean/spell_checkers/null_checker.rb
@@ -0,0 +1,6 @@
+module DidYouMean
+  class NullChecker
+    def initialize(*);  end
+    def corrections; [] end
+  end
+end
diff --git a/lib/did_you_mean/spell_checkers/pattern_key_name_checker.rb b/lib/did_you_mean/spell_checkers/pattern_key_name_checker.rb
new file mode 100644
index 0000000000..622d4dee25
--- /dev/null
+++ b/lib/did_you_mean/spell_checkers/pattern_key_name_checker.rb
@@ -0,0 +1,28 @@
+require_relative "../spell_checker"
+
+module DidYouMean
+  class PatternKeyNameChecker
+    def initialize(no_matching_pattern_key_error)
+      @key = no_matching_pattern_key_error.key
+      @keys = no_matching_pattern_key_error.matchee.keys
+    end
+
+    def corrections
+      @corrections ||= exact_matches.empty? ? SpellChecker.new(dictionary: @keys).correct(@key).map(&:inspect) : exact_matches
+    end
+
+    private
+
+    def exact_matches
+      @exact_matches ||= @keys.select { |word| @key == word.to_s }.map { |obj| format_object(obj) }
+    end
+
+    def format_object(symbol_or_object)
+      if symbol_or_object.is_a?(Symbol)
+        ":#{symbol_or_object}"
+      else
+        symbol_or_object.to_s
+      end
+    end
+  end
+end
diff --git a/lib/did_you_mean/spell_checkers/require_path_checker.rb b/lib/did_you_mean/spell_checkers/require_path_checker.rb
new file mode 100644
index 0000000000..586ced37de
--- /dev/null
+++ b/lib/did_you_mean/spell_checkers/require_path_checker.rb
@@ -0,0 +1,39 @@
+# frozen-string-literal: true
+
+require_relative "../spell_checker"
+require_relative "../tree_spell_checker"
+require "rbconfig"
+
+module DidYouMean
+  class RequirePathChecker
+    attr_reader :path
+
+    INITIAL_LOAD_PATH = $LOAD_PATH.dup.freeze
+    Ractor.make_shareable(INITIAL_LOAD_PATH) if defined?(Ractor)
+
+    ENV_SPECIFIC_EXT = ".#{RbConfig::CONFIG["DLEXT"]}"
+    Ractor.make_shareable(ENV_SPECIFIC_EXT) if defined?(Ractor)
+
+    private_constant :INITIAL_LOAD_PATH, :ENV_SPECIFIC_EXT
+
+    def self.requireables
+      @requireables ||= INITIAL_LOAD_PATH
+                          .flat_map {|path| Dir.glob("**/???*{.rb,#{ENV_SPECIFIC_EXT}}", base: path) }
+                          .map {|path| path.chomp!(".rb") || path.chomp!(ENV_SPECIFIC_EXT) }
+    end
+
+    def initialize(exception)
+      @path = exception.path
+    end
+
+    def corrections
+      @corrections ||= begin
+                         threshold     = path.size * 2
+                         dictionary    = self.class.requireables.reject {|str| str.size >= threshold }
+                         spell_checker = path.include?("/") ? TreeSpellChecker : SpellChecker
+
+                         spell_checker.new(dictionary: dictionary).correct(path).uniq
+                       end
+    end
+  end
+end
diff --git a/lib/did_you_mean/tree_spell_checker.rb b/lib/did_you_mean/tree_spell_checker.rb
new file mode 100644
index 0000000000..799f07fcf0
--- /dev/null
+++ b/lib/did_you_mean/tree_spell_checker.rb
@@ -0,0 +1,109 @@
+# frozen_string_literal: true
+
+module DidYouMean
+  # spell checker for a dictionary that has a tree
+  # structure, see doc/tree_spell_checker_api.md
+  class TreeSpellChecker
+    attr_reader :dictionary, :separator, :augment
+
+    def initialize(dictionary:, separator: '/', augment: nil)
+      @dictionary = dictionary
+      @separator = separator
+      @augment = augment
+    end
+
+    def correct(input)
+      plausibles = plausible_dimensions(input)
+      return fall_back_to_normal_spell_check(input) if plausibles.empty?
+
+      suggestions = find_suggestions(input, plausibles)
+      return fall_back_to_normal_spell_check(input) if suggestions.empty?
+
+      suggestions
+    end
+
+    def dictionary_without_leaves
+      @dictionary_without_leaves ||= dictionary.map { |word| word.split(separator)[0..-2] }.uniq
+    end
+
+    def tree_depth
+      @tree_depth ||= dictionary_without_leaves.max { |a, b| a.size <=> b.size }.size
+    end
+
+    def dimensions
+      @dimensions ||= tree_depth.times.map do |index|
+                        dictionary_without_leaves.map { |element| element[index] }.compact.uniq
+                      end
+    end
+
+    def find_leaves(path)
+      path_with_separator = "#{path}#{separator}"
+
+      dictionary
+        .select {|str| str.include?(path_with_separator) }
+        .map {|str| str.gsub(path_with_separator, '') }
+    end
+
+    def plausible_dimensions(input)
+      input.split(separator)[0..-2]
+        .map
+        .with_index { |element, index| correct_element(dimensions[index], element) if dimensions[index] }
+        .compact
+    end
+
+    def possible_paths(states)
+      states.map { |state| state.join(separator) }
+    end
+
+    private
+
+    def find_suggestions(input, plausibles)
+      states = plausibles[0].product(*plausibles[1..-1])
+      paths  = possible_paths(states)
+      leaf   = input.split(separator).last
+
+      find_ideas(paths, leaf)
+    end
+
+    def fall_back_to_normal_spell_check(input)
+      return [] unless augment
+
+      ::DidYouMean::SpellChecker.new(dictionary: dictionary).correct(input)
+    end
+
+    def find_ideas(paths, leaf)
+      paths.flat_map do |path|
+        names = find_leaves(path)
+        ideas = correct_element(names, leaf)
+
+        ideas_to_paths(ideas, leaf, names, path)
+      end.compact
+    end
+
+    def ideas_to_paths(ideas, leaf, names, path)
+      if ideas.empty?
+        nil
+      elsif names.include?(leaf)
+        ["#{path}#{separator}#{leaf}"]
+      else
+        ideas.map {|str| "#{path}#{separator}#{str}" }
+      end
+    end
+
+    def correct_element(names, element)
+      return names if names.size == 1
+
+      str = normalize(element)
+
+      return [str] if names.include?(str)
+
+      ::DidYouMean::SpellChecker.new(dictionary: names).correct(str)
+    end
+
+    def normalize(str)
+      str.downcase!
+      str.tr!('@', ' ') if str.include?('@')
+      str
+    end
+  end
+end
diff --git a/lib/did_you_mean/verbose.rb b/lib/did_you_mean/verbose.rb
new file mode 100644
index 0000000000..1ff19aef80
--- /dev/null
+++ b/lib/did_you_mean/verbose.rb
@@ -0,0 +1,2 @@
+warn "The verbose formatter has been removed and now `require 'did_you_mean/verbose'` has no effect. Please " \
+     "remove this call."
diff --git a/lib/did_you_mean/version.rb b/lib/did_you_mean/version.rb
new file mode 100644
index 0000000000..85d80e4230
--- /dev/null
+++ b/lib/did_you_mean/version.rb
@@ -0,0 +1,3 @@
+module DidYouMean
+  VERSION = "2.0.0".freeze
+end
diff --git a/lib/drb.rb b/lib/drb.rb
deleted file mode 100644
index 93cc811e14..0000000000
--- a/lib/drb.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-require 'drb/drb'
-
diff --git a/lib/drb/acl.rb b/lib/drb/acl.rb
deleted file mode 100644
index 29a378199f..0000000000
--- a/lib/drb/acl.rb
+++ /dev/null
@@ -1,250 +0,0 @@
-# Copyright (c) 2000,2002,2003 Masatoshi SEKI
-#
-# acl.rb is copyrighted free software by Masatoshi SEKI.
-# You can redistribute it and/or modify it under the same terms as Ruby.
-
-require 'ipaddr'
-
-##
-# Simple Access Control Lists.
-#
-# Access control lists are composed of "allow" and "deny" halves to control
-# access.  Use "all" or "*" to match any address.  To match a specific address
-# use any address or address mask that IPAddr can understand.
-#
-# Example:
-#
-#   list = %w[
-#     deny all
-#     allow 192.168.1.1
-#     allow ::ffff:192.168.1.2
-#     allow 192.168.1.3
-#   ]
-#
-#   # From Socket#peeraddr, see also ACL#allow_socket?
-#   addr = ["AF_INET", 10, "lc630", "192.168.1.3"]
-#
-#   acl = ACL.new
-#   p acl.allow_addr?(addr) # => true
-#
-#   acl = ACL.new(list, ACL::DENY_ALLOW)
-#   p acl.allow_addr?(addr) # => true
-
-class ACL
-
-  ##
-  # The current version of ACL
-
-  VERSION=["2.0.0"]
-
-  ##
-  # An entry in an ACL
-
-  class ACLEntry
-
-    ##
-    # Creates a new entry using +str+.
-    #
-    # +str+ may be "*" or "all" to match any address, an IP address string
-    # to match a specific address, an IP address mask per IPAddr, or one
-    # containing "*" to match part of an IPv4 address.
-
-    def initialize(str)
-      if str == '*' or str == 'all'
-        @pat = [:all]
-      elsif str.include?('*')
-        @pat = [:name, dot_pat(str)]
-      else
-        begin
-          @pat = [:ip, IPAddr.new(str)]
-        rescue ArgumentError
-          @pat = [:name, dot_pat(str)]
-        end
-      end
-    end
-
-    private
-
-    ##
-    # Creates a regular expression to match IPv4 addresses
-
-    def dot_pat_str(str)
-      list = str.split('.').collect { |s|
-        (s == '*') ? '.+' : s
-      }
-      list.join("\\.")
-    end
-
-    private
-
-    ##
-    # Creates a Regexp to match an address.
-
-    def dot_pat(str)
-      exp = "^" + dot_pat_str(str) + "$"
-      Regexp.new(exp)
-    end
-
-    public
-
-    ##
-    # Matches +addr+ against this entry.
-
-    def match(addr)
-      case @pat[0]
-      when :all
-        true
-      when :ip
-        begin
-          ipaddr = IPAddr.new(addr[3])
-          ipaddr = ipaddr.ipv4_mapped if @pat[1].ipv6? && ipaddr.ipv4?
-        rescue ArgumentError
-          return false
-        end
-        (@pat[1].include?(ipaddr)) ? true : false
-      when :name
-        (@pat[1] =~ addr[2]) ? true : false
-      else
-        false
-      end
-    end
-  end
-
-  ##
-  # A list of ACLEntry objects.  Used to implement the allow and deny halves
-  # of an ACL
-
-  class ACLList
-
-    ##
-    # Creates an empty ACLList
-
-    def initialize
-      @list = []
-    end
-
-    public
-
-    ##
-    # Matches +addr+ against each ACLEntry in this list.
-
-    def match(addr)
-      @list.each do |e|
-        return true if e.match(addr)
-      end
-      false
-    end
-
-    public
-
-    ##
-    # Adds +str+ as an ACLEntry in this list
-
-    def add(str)
-      @list.push(ACLEntry.new(str))
-    end
-
-  end
-
-  ##
-  # Default to deny
-
-  DENY_ALLOW = 0
-
-  ##
-  # Default to allow
-
-  ALLOW_DENY = 1
-
-  ##
-  # Creates a new ACL from +list+ with an evaluation +order+ of DENY_ALLOW or
-  # ALLOW_DENY.
-  #
-  # An ACL +list+ is an Array of "allow" or "deny" and an address or address
-  # mask or "all" or "*" to match any address:
-  #
-  #   %w[
-  #     deny all
-  #     allow 192.0.2.2
-  #     allow 192.0.2.128/26
-  #   ]
-
-  def initialize(list=nil, order = DENY_ALLOW)
-    @order = order
-    @deny = ACLList.new
-    @allow = ACLList.new
-    install_list(list) if list
-  end
-
-  public
-
-  ##
-  # Allow connections from Socket +soc+?
-
-  def allow_socket?(soc)
-    allow_addr?(soc.peeraddr)
-  end
-
-  public
-
-  ##
-  # Allow connections from addrinfo +addr+?  It must be formatted like
-  # Socket#peeraddr:
-  #
-  #   ["AF_INET", 10, "lc630", "192.0.2.1"]
-
-  def allow_addr?(addr)
-    case @order
-    when DENY_ALLOW
-      return true if @allow.match(addr)
-      return false if @deny.match(addr)
-      return true
-    when ALLOW_DENY
-      return false if @deny.match(addr)
-      return true if @allow.match(addr)
-      return false
-    else
-      false
-    end
-  end
-
-  public
-
-  ##
-  # Adds +list+ of ACL entries to this ACL.
-
-  def install_list(list)
-    i = 0
-    while i < list.size
-      permission, domain = list.slice(i,2)
-      case permission.downcase
-      when 'allow'
-        @allow.add(domain)
-      when 'deny'
-        @deny.add(domain)
-      else
-        raise "Invalid ACL entry #{list.to_s}"
-      end
-      i += 2
-    end
-  end
-
-end
-
-if __FILE__ == $0
-  # example
-  list = %w(deny all
-            allow 192.168.1.1
-            allow ::ffff:192.168.1.2
-            allow 192.168.1.3
-            )
-
-  addr = ["AF_INET", 10, "lc630", "192.168.1.3"]
-
-  acl = ACL.new
-  p acl.allow_addr?(addr)
-
-  acl = ACL.new(list, ACL::DENY_ALLOW)
-  p acl.allow_addr?(addr)
-end
-
diff --git a/lib/drb/drb.rb b/lib/drb/drb.rb
deleted file mode 100644
index 69456b1db2..0000000000
--- a/lib/drb/drb.rb
+++ /dev/null
@@ -1,1774 +0,0 @@
-#
-# = drb/drb.rb
-#
-# Distributed Ruby: _dRuby_ version 2.0.4
-#
-# Copyright (c) 1999-2003 Masatoshi SEKI.  You can redistribute it and/or
-# modify it under the same terms as Ruby.
-#
-# Author:: Masatoshi SEKI
-#
-# Documentation:: William Webber (william@williamwebber.com)
-#
-# == Overview
-#
-# dRuby is a distributed object system for Ruby.  It allows an object in one
-# Ruby process to invoke methods on an object in another Ruby process on the
-# same or a different machine.
-#
-# The Ruby standard library contains the core classes of the dRuby package.
-# However, the full package also includes access control lists and the
-# Rinda tuple-space distributed task management system, as well as a
-# large number of samples.  The full dRuby package can be downloaded from
-# the dRuby home page (see *References*).
-#
-# For an introduction and examples of usage see the documentation to the
-# DRb module.
-#
-# == References
-#
-# [http://www2a.biglobe.ne.jp/~seki/ruby/druby.html]
-#    The dRuby home page, in Japanese.  Contains the full dRuby package
-#    and links to other Japanese-language sources.
-#
-# [http://www2a.biglobe.ne.jp/~seki/ruby/druby.en.html]
-#    The English version of the dRuby home page.
-#
-# [http://www.chadfowler.com/ruby/drb.html]
-#    A quick tutorial introduction to using dRuby by Chad Fowler.
-#
-# [http://www.linux-mag.com/2002-09/ruby_05.html]
-#   A tutorial introduction to dRuby in Linux Magazine by Dave Thomas.
-#   Includes a discussion of Rinda.
-#
-# [http://www.eng.cse.dmu.ac.uk/~hgs/ruby/dRuby/]
-#   Links to English-language Ruby material collected by Hugh Sasse.
-#
-# [http://www.rubycentral.com/book/ospace.html]
-#   The chapter from *Programming* *Ruby* by Dave Thomas and Andy Hunt
-#   which discusses dRuby.
-#
-# [http://www.clio.ne.jp/home/web-i31s/Flotuard/Ruby/PRC2K_seki/dRuby.en.html]
-#   Translation of presentation on Ruby by Masatoshi Seki.
-
-require 'socket'
-require 'thread'
-require 'fcntl'
-require 'drb/eq'
-
-#
-# == Overview
-#
-# dRuby is a distributed object system for Ruby.  It is written in
-# pure Ruby and uses its own protocol.  No add-in services are needed
-# beyond those provided by the Ruby runtime, such as TCP sockets.  It
-# does not rely on or interoperate with other distributed object
-# systems such as CORBA, RMI, or .NET.
-#
-# dRuby allows methods to be called in one Ruby process upon a Ruby
-# object located in another Ruby process, even on another machine.
-# References to objects can be passed between processes.  Method
-# arguments and return values are dumped and loaded in marshalled
-# format.  All of this is done transparently to both the caller of the
-# remote method and the object that it is called upon.
-#
-# An object in a remote process is locally represented by a
-# DRb::DRbObject instance.  This acts as a sort of proxy for the
-# remote object.  Methods called upon this DRbObject instance are
-# forwarded to its remote object.  This is arranged dynamically at run
-# time.  There are no statically declared interfaces for remote
-# objects, such as CORBA's IDL.
-#
-# dRuby calls made into a process are handled by a DRb::DRbServer
-# instance within that process.  This reconstitutes the method call,
-# invokes it upon the specified local object, and returns the value to
-# the remote caller.  Any object can receive calls over dRuby.  There
-# is no need to implement a special interface, or mixin special
-# functionality.  Nor, in the general case, does an object need to
-# explicitly register itself with a DRbServer in order to receive
-# dRuby calls.
-#
-# One process wishing to make dRuby calls upon another process must
-# somehow obtain an initial reference to an object in the remote
-# process by some means other than as the return value of a remote
-# method call, as there is initially no remote object reference it can
-# invoke a method upon.  This is done by attaching to the server by
-# URI.  Each DRbServer binds itself to a URI such as
-# 'druby://example.com:8787'.  A DRbServer can have an object attached
-# to it that acts as the server's *front* *object*.  A DRbObject can
-# be explicitly created from the server's URI.  This DRbObject's
-# remote object will be the server's front object.  This front object
-# can then return references to other Ruby objects in the DRbServer's
-# process.
-#
-# Method calls made over dRuby behave largely the same as normal Ruby
-# method calls made within a process.  Method calls with blocks are
-# supported, as are raising exceptions.  In addition to a method's
-# standard errors, a dRuby call may also raise one of the
-# dRuby-specific errors, all of which are subclasses of DRb::DRbError.
-#
-# Any type of object can be passed as an argument to a dRuby call or
-# returned as its return value.  By default, such objects are dumped
-# or marshalled at the local end, then loaded or unmarshalled at the
-# remote end.  The remote end therefore receives a copy of the local
-# object, not a distributed reference to it; methods invoked upon this
-# copy are executed entirely in the remote process, not passed on to
-# the local original.  This has semantics similar to pass-by-value.
-#
-# However, if an object cannot be marshalled, a dRuby reference to it
-# is passed or returned instead.  This will turn up at the remote end
-# as a DRbObject instance.  All methods invoked upon this remote proxy
-# are forwarded to the local object, as described in the discussion of
-# DRbObjects.  This has semantics similar to the normal Ruby
-# pass-by-reference.
-#
-# The easiest way to signal that we want an otherwise marshallable
-# object to be passed or returned as a DRbObject reference, rather
-# than marshalled and sent as a copy, is to include the
-# DRb::DRbUndumped mixin module.
-#
-# dRuby supports calling remote methods with blocks.  As blocks (or
-# rather the Proc objects that represent them) are not marshallable,
-# the block executes in the local, not the remote, context.  Each
-# value yielded to the block is passed from the remote object to the
-# local block, then the value returned by each block invocation is
-# passed back to the remote execution context to be collected, before
-# the collected values are finally returned to the local context as
-# the return value of the method invocation.
-#
-# == Examples of usage
-#
-# For more dRuby samples, see the +samples+ directory in the full
-# dRuby distribution.
-#
-# === dRuby in client/server mode
-#
-# This illustrates setting up a simple client-server drb
-# system.  Run the server and client code in different terminals,
-# starting the server code first.
-#
-# ==== Server code
-#
-#   require 'drb/drb'
-#
-#   # The URI for the server to connect to
-#   URI="druby://localhost:8787"
-#
-#   class TimeServer
-#
-#     def get_current_time
-#       return Time.now
-#     end
-#
-#   end
-#
-#   # The object that handles requests on the server
-#   FRONT_OBJECT=TimeServer.new
-#
-#   $SAFE = 1   # disable eval() and friends
-#
-#   DRb.start_service(URI, FRONT_OBJECT)
-#   # Wait for the drb server thread to finish before exiting.
-#   DRb.thread.join
-#
-# ==== Client code
-#
-#   require 'drb/drb'
-#
-#   # The URI to connect to
-#   SERVER_URI="druby://localhost:8787"
-#
-#   # Start a local DRbServer to handle callbacks.
-#   #
-#   # Not necessary for this small example, but will be required
-#   # as soon as we pass a non-marshallable object as an argument
-#   # to a dRuby call.
-#   DRb.start_service
-#
-#   timeserver = DRbObject.new_with_uri(SERVER_URI)
-#   puts timeserver.get_current_time
-#
-# === Remote objects under dRuby
-#
-# This example illustrates returning a reference to an object
-# from a dRuby call.  The Logger instances live in the server
-# process.  References to them are returned to the client process,
-# where methods can be invoked upon them.  These methods are
-# executed in the server process.
-#
-# ==== Server code
-#
-#   require 'drb/drb'
-#
-#   URI="druby://localhost:8787"
-#
-#   class Logger
-#
-#       # Make dRuby send Logger instances as dRuby references,
-#       # not copies.
-#       include DRb::DRbUndumped
-#
-#       def initialize(n, fname)
-#           @name = n
-#           @filename = fname
-#       end
-#
-#       def log(message)
-#           File.open(@filename, "a") do |f|
-#               f.puts("#{Time.now}: #{@name}: #{message}")
-#           end
-#       end
-#
-#   end
-#
-#   # We have a central object for creating and retrieving loggers.
-#   # This retains a local reference to all loggers created.  This
-#   # is so an existing logger can be looked up by name, but also
-#   # to prevent loggers from being garbage collected.  A dRuby
-#   # reference to an object is not sufficient to prevent it being
-#   # garbage collected!
-#   class LoggerFactory
-#
-#       def initialize(bdir)
-#           @basedir = bdir
-#           @loggers = {}
-#       end
-#
-#       def get_logger(name)
-#           if !@loggers.has_key? name
-#               # make the filename safe, then declare it to be so
-#               fname = name.gsub(/[.\/]/, "_").untaint
-#               @loggers[name] = Logger.new(name, @basedir + "/" + fname)
-#           end
-#           return @loggers[name]
-#       end
-#
-#   end
-#
-#   FRONT_OBJECT=LoggerFactory.new("/tmp/dlog")
-#
-#   $SAFE = 1   # disable eval() and friends
-#
-#   DRb.start_service(URI, FRONT_OBJECT)
-#   DRb.thread.join
-#
-# ==== Client code
-#
-#   require 'drb/drb'
-#
-#   SERVER_URI="druby://localhost:8787"
-#
-#   DRb.start_service
-#
-#   log_service=DRbObject.new_with_uri(SERVER_URI)
-#
-#   ["loga", "logb", "logc"].each do |logname|
-#
-#       logger=log_service.get_logger(logname)
-#
-#       logger.log("Hello, world!")
-#       logger.log("Goodbye, world!")
-#       logger.log("=== EOT ===")
-#
-#   end
-#
-# == Security
-#
-# As with all network services, security needs to be considered when
-# using dRuby.  By allowing external access to a Ruby object, you are
-# not only allowing outside clients to call the methods you have
-# defined for that object, but by default to execute arbitrary Ruby
-# code on your server.  Consider the following:
-#
-#    # !!! UNSAFE CODE !!!
-#    ro = DRbObject::new_with_uri("druby://your.server.com:8989")
-#    class << ro
-#      undef :instance_eval  # force call to be passed to remote object
-#    end
-#    ro.instance_eval("`rm -rf *`")
-#
-# The dangers posed by instance_eval and friends are such that a
-# DRbServer should generally be run with $SAFE set to at least
-# level 1.  This will disable eval() and related calls on strings
-# passed across the wire.  The sample usage code given above follows
-# this practice.
-#
-# A DRbServer can be configured with an access control list to
-# selectively allow or deny access from specified IP addresses.  The
-# main druby distribution provides the ACL class for this purpose.  In
-# general, this mechanism should only be used alongside, rather than
-# as a replacement for, a good firewall.
-#
-# == dRuby internals
-#
-# dRuby is implemented using three main components: a remote method
-# call marshaller/unmarshaller; a transport protocol; and an
-# ID-to-object mapper.  The latter two can be directly, and the first
-# indirectly, replaced, in order to provide different behaviour and
-# capabilities.
-#
-# Marshalling and unmarshalling of remote method calls is performed by
-# a DRb::DRbMessage instance.  This uses the Marshal module to dump
-# the method call before sending it over the transport layer, then
-# reconstitute it at the other end.  There is normally no need to
-# replace this component, and no direct way is provided to do so.
-# However, it is possible to implement an alternative marshalling
-# scheme as part of an implementation of the transport layer.
-#
-# The transport layer is responsible for opening client and server
-# network connections and forwarding dRuby request across them.
-# Normally, it uses DRb::DRbMessage internally to manage marshalling
-# and unmarshalling.  The transport layer is managed by
-# DRb::DRbProtocol.  Multiple protocols can be installed in
-# DRbProtocol at the one time; selection between them is determined by
-# the scheme of a dRuby URI.  The default transport protocol is
-# selected by the scheme 'druby:', and implemented by
-# DRb::DRbTCPSocket.  This uses plain TCP/IP sockets for
-# communication.  An alternative protocol, using UNIX domain sockets,
-# is implemented by DRb::DRbUNIXSocket in the file drb/unix.rb, and
-# selected by the scheme 'drbunix:'.  A sample implementation over
-# HTTP can be found in the samples accompanying the main dRuby
-# distribution.
-#
-# The ID-to-object mapping component maps dRuby object ids to the
-# objects they refer to, and vice versa.  The implementation to use
-# can be specified as part of a DRb::DRbServer's configuration.  The
-# default implementation is provided by DRb::DRbIdConv.  It uses an
-# object's ObjectSpace id as its dRuby id.  This means that the dRuby
-# reference to that object only remains meaningful for the lifetime of
-# the object's process and the lifetime of the object within that
-# process.  A modified implementation is provided by DRb::TimerIdConv
-# in the file drb/timeridconv.rb.  This implementation retains a local
-# reference to all objects exported over dRuby for a configurable
-# period of time (defaulting to ten minutes), to prevent them being
-# garbage-collected within this time.  Another sample implementation
-# is provided in sample/name.rb in the main dRuby distribution.  This
-# allows objects to specify their own id or "name".  A dRuby reference
-# can be made persistent across processes by having each process
-# register an object using the same dRuby name.
-#
-module DRb
-
-  # Superclass of all errors raised in the DRb module.
-  class DRbError < RuntimeError; end
-
-  # Error raised when an error occurs on the underlying communication
-  # protocol.
-  class DRbConnError < DRbError; end
-
-  # Class responsible for converting between an object and its id.
-  #
-  # This, the default implementation, uses an object's local ObjectSpace
-  # __id__ as its id.  This means that an object's identification over
-  # drb remains valid only while that object instance remains alive
-  # within the server runtime.
-  #
-  # For alternative mechanisms, see DRb::TimerIdConv in rdb/timeridconv.rb
-  # and DRbNameIdConv in sample/name.rb in the full drb distribution.
-  class DRbIdConv
-
-    # Convert an object reference id to an object.
-    #
-    # This implementation looks up the reference id in the local object
-    # space and returns the object it refers to.
-    def to_obj(ref)
-      ObjectSpace._id2ref(ref)
-    end
-
-    # Convert an object into a reference id.
-    #
-    # This implementation returns the object's __id__ in the local
-    # object space.
-    def to_id(obj)
-      obj.nil? ? nil : obj.__id__
-    end
-  end
-
-  # Mixin module making an object undumpable or unmarshallable.
-  #
-  # If an object which includes this module is returned by method
-  # called over drb, then the object remains in the server space
-  # and a reference to the object is returned, rather than the
-  # object being marshalled and moved into the client space.
-  module DRbUndumped
-    def _dump(dummy)  # :nodoc:
-      raise TypeError, 'can\'t dump'
-    end
-  end
-
-  # Error raised by the DRb module when an attempt is made to refer to
-  # the context's current drb server but the context does not have one.
-  # See #current_server.
-  class DRbServerNotFound < DRbError; end
-
-  # Error raised by the DRbProtocol module when it cannot find any
-  # protocol implementation support the scheme specified in a URI.
-  class DRbBadURI < DRbError; end
-
-  # Error raised by a dRuby protocol when it doesn't support the
-  # scheme specified in a URI.  See DRb::DRbProtocol.
-  class DRbBadScheme < DRbError; end
-
-  # An exception wrapping a DRb::DRbUnknown object
-  class DRbUnknownError < DRbError
-
-    # Create a new DRbUnknownError for the DRb::DRbUnknown object +unknown+
-    def initialize(unknown)
-      @unknown = unknown
-      super(unknown.name)
-    end
-
-    # Get the wrapped DRb::DRbUnknown object.
-    attr_reader :unknown
-
-    def self._load(s)  # :nodoc:
-      Marshal::load(s)
-    end
-
-    def _dump(lv) # :nodoc:
-      Marshal::dump(@unknown)
-    end
-  end
-
-  # An exception wrapping an error object
-  class DRbRemoteError < DRbError
-    def initialize(error)
-      @reason = error.class.to_s
-      super("#{error.message} (#{error.class})")
-      set_backtrace(error.backtrace)
-    end
-
-    # the class of the error, as a string.
-    attr_reader :reason
-  end
-
-  # Class wrapping a marshalled object whose type is unknown locally.
-  #
-  # If an object is returned by a method invoked over drb, but the
-  # class of the object is unknown in the client namespace, or
-  # the object is a constant unknown in the client namespace, then
-  # the still-marshalled object is returned wrapped in a DRbUnknown instance.
-  #
-  # If this object is passed as an argument to a method invoked over
-  # drb, then the wrapped object is passed instead.
-  #
-  # The class or constant name of the object can be read from the
-  # +name+ attribute.  The marshalled object is held in the +buf+
-  # attribute.
-  class DRbUnknown
-
-    # Create a new DRbUnknown object.
-    #
-    # +buf+ is a string containing a marshalled object that could not
-    # be unmarshalled.  +err+ is the error message that was raised
-    # when the unmarshalling failed.  It is used to determine the
-    # name of the unmarshalled object.
-    def initialize(err, buf)
-      case err.to_s
-      when /uninitialized constant (\S+)/
-        @name = $1
-      when /undefined class\/module (\S+)/
-        @name = $1
-      else
-        @name = nil
-      end
-      @buf = buf
-    end
-
-    # The name of the unknown thing.
-    #
-    # Class name for unknown objects; variable name for unknown
-    # constants.
-    attr_reader :name
-
-    # Buffer contained the marshalled, unknown object.
-    attr_reader :buf
-
-    def self._load(s) # :nodoc:
-      begin
-        Marshal::load(s)
-      rescue NameError, ArgumentError
-        DRbUnknown.new($!, s)
-      end
-    end
-
-    def _dump(lv) # :nodoc:
-      @buf
-    end
-
-    # Attempt to load the wrapped marshalled object again.
-    #
-    # If the class of the object is now known locally, the object
-    # will be unmarshalled and returned.  Otherwise, a new
-    # but identical DRbUnknown object will be returned.
-    def reload
-      self.class._load(@buf)
-    end
-
-    # Create a DRbUnknownError exception containing this object.
-    def exception
-      DRbUnknownError.new(self)
-    end
-  end
-
-  class DRbArray
-    def initialize(ary)
-      @ary = ary.collect { |obj|
-        if obj.kind_of? DRbUndumped
-          DRbObject.new(obj)
-        else
-          begin
-            Marshal.dump(obj)
-            obj
-          rescue
-            DRbObject.new(obj)
-          end
-        end
-      }
-    end
-
-    def self._load(s)
-      Marshal::load(s)
-    end
-
-    def _dump(lv)
-      Marshal.dump(@ary)
-    end
-  end
-
-  # Handler for sending and receiving drb messages.
-  #
-  # This takes care of the low-level marshalling and unmarshalling
-  # of drb requests and responses sent over the wire between server
-  # and client.  This relieves the implementor of a new drb
-  # protocol layer with having to deal with these details.
-  #
-  # The user does not have to directly deal with this object in
-  # normal use.
-  class DRbMessage
-    def initialize(config) # :nodoc:
-      @load_limit = config[:load_limit]
-      @argc_limit = config[:argc_limit]
-    end
-
-    def dump(obj, error=false)  # :nodoc:
-      obj = make_proxy(obj, error) if obj.kind_of? DRbUndumped
-      begin
-        str = Marshal::dump(obj)
-      rescue
-        str = Marshal::dump(make_proxy(obj, error))
-      end
-      [str.size].pack('N') + str
-    end
-
-    def load(soc)  # :nodoc:
-      begin
-        sz = soc.read(4)        # sizeof (N)
-      rescue
-        raise(DRbConnError, $!.message, $!.backtrace)
-      end
-      raise(DRbConnError, 'connection closed') if sz.nil?
-      raise(DRbConnError, 'premature header') if sz.size < 4
-      sz = sz.unpack('N')[0]
-      raise(DRbConnError, "too large packet #{sz}") if @load_limit < sz
-      begin
-        str = soc.read(sz)
-      rescue
-        raise(DRbConnError, $!.message, $!.backtrace)
-      end
-      raise(DRbConnError, 'connection closed') if str.nil?
-      raise(DRbConnError, 'premature marshal format(can\'t read)') if str.size < sz
-      DRb.mutex.synchronize do
-        begin
-          save = Thread.current[:drb_untaint]
-          Thread.current[:drb_untaint] = []
-          Marshal::load(str)
-        rescue NameError, ArgumentError
-          DRbUnknown.new($!, str)
-        ensure
-          Thread.current[:drb_untaint].each do |x|
-            x.untaint
-          end
-          Thread.current[:drb_untaint] = save
-        end
-      end
-    end
-
-    def send_request(stream, ref, msg_id, arg, b) # :nodoc:
-      ary = []
-      ary.push(dump(ref.__drbref))
-      ary.push(dump(msg_id.id2name))
-      ary.push(dump(arg.length))
-      arg.each do |e|
-        ary.push(dump(e))
-      end
-      ary.push(dump(b))
-      stream.write(ary.join(''))
-    rescue
-      raise(DRbConnError, $!.message, $!.backtrace)
-    end
-
-    def recv_request(stream) # :nodoc:
-      ref = load(stream)
-      ro = DRb.to_obj(ref)
-      msg = load(stream)
-      argc = load(stream)
-      raise(DRbConnError, "too many arguments") if @argc_limit < argc
-      argv = Array.new(argc, nil)
-      argc.times do |n|
-        argv[n] = load(stream)
-      end
-      block = load(stream)
-      return ro, msg, argv, block
-    end
-
-    def send_reply(stream, succ, result)  # :nodoc:
-      stream.write(dump(succ) + dump(result, !succ))
-    rescue
-      raise(DRbConnError, $!.message, $!.backtrace)
-    end
-
-    def recv_reply(stream)  # :nodoc:
-      succ = load(stream)
-      result = load(stream)
-      [succ, result]
-    end
-
-    private
-    def make_proxy(obj, error=false)
-      if error
-        DRbRemoteError.new(obj)
-      else
-        DRbObject.new(obj)
-      end
-    end
-  end
-
-  # Module managing the underlying network protocol(s) used by drb.
-  #
-  # By default, drb uses the DRbTCPSocket protocol.  Other protocols
-  # can be defined.  A protocol must define the following class methods:
-  #
-  #   [open(uri, config)] Open a client connection to the server at +uri+,
-  #                       using configuration +config+.  Return a protocol
-  #                       instance for this connection.
-  #   [open_server(uri, config)] Open a server listening at +uri+,
-  #                              using configuration +config+.  Return a
-  #                              protocol instance for this listener.
-  #   [uri_option(uri, config)] Take a URI, possibly containing an option
-  #                             component (e.g. a trailing '?param=val'),
-  #                             and return a [uri, option] tuple.
-  #
-  # All of these methods should raise a DRbBadScheme error if the URI
-  # does not identify the protocol they support (e.g. "druby:" for
-  # the standard Ruby protocol).  This is how the DRbProtocol module,
-  # given a URI, determines which protocol implementation serves that
-  # protocol.
-  #
-  # The protocol instance returned by #open_server must have the
-  # following methods:
-  #
-  # [accept] Accept a new connection to the server.  Returns a protocol
-  #          instance capable of communicating with the client.
-  # [close] Close the server connection.
-  # [uri] Get the URI for this server.
-  #
-  # The protocol instance returned by #open must have the following methods:
-  #
-  # [send_request (ref, msg_id, arg, b)]
-  #      Send a request to +ref+ with the given message id and arguments.
-  #      This is most easily implemented by calling DRbMessage.send_request,
-  #      providing a stream that sits on top of the current protocol.
-  # [recv_reply]
-  #      Receive a reply from the server and return it as a [success-boolean,
-  #      reply-value] pair.  This is most easily implemented by calling
-  #      DRb.recv_reply, providing a stream that sits on top of the
-  #      current protocol.
-  # [alive?]
-  #      Is this connection still alive?
-  # [close]
-  #      Close this connection.
-  #
-  # The protocol instance returned by #open_server().accept() must have
-  # the following methods:
-  #
-  # [recv_request]
-  #     Receive a request from the client and return a [object, message,
-  #     args, block] tuple.  This is most easily implemented by calling
-  #     DRbMessage.recv_request, providing a stream that sits on top of
-  #     the current protocol.
-  # [send_reply(succ, result)]
-  #     Send a reply to the client.  This is most easily implemented
-  #     by calling DRbMessage.send_reply, providing a stream that sits
-  #     on top of the current protocol.
-  # [close]
-  #     Close this connection.
-  #
-  # A new protocol is registered with the DRbProtocol module using
-  # the add_protocol method.
-  #
-  # For examples of other protocols, see DRbUNIXSocket in drb/unix.rb,
-  # and HTTP0 in sample/http0.rb and sample/http0serv.rb in the full
-  # drb distribution.
-  module DRbProtocol
-
-    # Add a new protocol to the DRbProtocol module.
-    def add_protocol(prot)
-      @protocol.push(prot)
-    end
-    module_function :add_protocol
-
-    # Open a client connection to +uri+ with the configuration +config+.
-    #
-    # The DRbProtocol module asks each registered protocol in turn to
-    # try to open the URI.  Each protocol signals that it does not handle that
-    # URI by raising a DRbBadScheme error.  If no protocol recognises the
-    # URI, then a DRbBadURI error is raised.  If a protocol accepts the
-    # URI, but an error occurs in opening it, a DRbConnError is raised.
-    def open(uri, config, first=true)
-      @protocol.each do |prot|
-        begin
-          return prot.open(uri, config)
-        rescue DRbBadScheme
-        rescue DRbConnError
-          raise($!)
-        rescue
-          raise(DRbConnError, "#{uri} - #{$!.inspect}")
-        end
-      end
-      if first && (config[:auto_load] != false)
-        auto_load(uri, config)
-        return open(uri, config, false)
-      end
-      raise DRbBadURI, 'can\'t parse uri:' + uri
-    end
-    module_function :open
-
-    # Open a server listening for connections at +uri+ with
-    # configuration +config+.
-    #
-    # The DRbProtocol module asks each registered protocol in turn to
-    # try to open a server at the URI.  Each protocol signals that it does
-    # not handle that URI by raising a DRbBadScheme error.  If no protocol
-    # recognises the URI, then a DRbBadURI error is raised.  If a protocol
-    # accepts the URI, but an error occurs in opening it, the underlying
-    # error is passed on to the caller.
-    def open_server(uri, config, first=true)
-      @protocol.each do |prot|
-        begin
-          return prot.open_server(uri, config)
-        rescue DRbBadScheme
-        end
-      end
-      if first && (config[:auto_load] != false)
-        auto_load(uri, config)
-        return open_server(uri, config, false)
-      end
-      raise DRbBadURI, 'can\'t parse uri:' + uri
-    end
-    module_function :open_server
-
-    # Parse +uri+ into a [uri, option] pair.
-    #
-    # The DRbProtocol module asks each registered protocol in turn to
-    # try to parse the URI.  Each protocol signals that it does not handle that
-    # URI by raising a DRbBadScheme error.  If no protocol recognises the
-    # URI, then a DRbBadURI error is raised.
-    def uri_option(uri, config, first=true)
-      @protocol.each do |prot|
-        begin
-          uri, opt = prot.uri_option(uri, config)
-          # opt = nil if opt == ''
-          return uri, opt
-        rescue DRbBadScheme
-        end
-      end
-      if first && (config[:auto_load] != false)
-        auto_load(uri, config)
-        return uri_option(uri, config, false)
-      end
-      raise DRbBadURI, 'can\'t parse uri:' + uri
-    end
-    module_function :uri_option
-
-    def auto_load(uri, config)  # :nodoc:
-      if uri =~ /^drb([a-z0-9]+):/
-        require("drb/#{$1}") rescue nil
-      end
-    end
-    module_function :auto_load
-  end
-
-  # The default drb protocol.
-  #
-  # Communicates over a TCP socket.
-  class DRbTCPSocket
-    private
-    def self.parse_uri(uri)
-      if uri =~ /^druby:\/\/(.*?):(\d+)(\?(.*))?$/
-        host = $1
-        port = $2.to_i
-        option = $4
-        [host, port, option]
-      else
-        raise(DRbBadScheme, uri) unless uri =~ /^druby:/
-        raise(DRbBadURI, 'can\'t parse uri:' + uri)
-      end
-    end
-
-    public
-
-    # Open a client connection to +uri+ using configuration +config+.
-    def self.open(uri, config)
-      host, port, = parse_uri(uri)
-      host.untaint
-      port.untaint
-      soc = TCPSocket.open(host, port)
-      self.new(uri, soc, config)
-    end
-
-    def self.getservername
-      host = Socket::gethostname
-      begin
-        Socket::gethostbyname(host)[0]
-      rescue
-        'localhost'
-      end
-    end
-
-    def self.open_server_inaddr_any(host, port)
-      infos = Socket::getaddrinfo(host, nil,
-                                  Socket::AF_UNSPEC,
-                                  Socket::SOCK_STREAM,
-                                  0,
-                                  Socket::AI_PASSIVE)
-      families = Hash[*infos.collect { |af, *_| af }.uniq.zip([]).flatten]
-      return TCPServer.open('0.0.0.0', port) if families.has_key?('AF_INET')
-      return TCPServer.open('::', port) if families.has_key?('AF_INET6')
-      return TCPServer.open(port)
-    end
-
-    # Open a server listening for connections at +uri+ using
-    # configuration +config+.
-    def self.open_server(uri, config)
-      uri = 'druby://:0' unless uri
-      host, port, _ = parse_uri(uri)
-      config = {:tcp_original_host => host}.update(config)
-      if host.size == 0
-        host = getservername
-        soc = open_server_inaddr_any(host, port)
-      else
-        soc = TCPServer.open(host, port)
-      end
-      port = soc.addr[1] if port == 0
-      config[:tcp_port] = port
-      uri = "druby://#{host}:#{port}"
-      self.new(uri, soc, config)
-    end
-
-    # Parse +uri+ into a [uri, option] pair.
-    def self.uri_option(uri, config)
-      host, port, option = parse_uri(uri)
-      return "druby://#{host}:#{port}", option
-    end
-
-    # Create a new DRbTCPSocket instance.
-    #
-    # +uri+ is the URI we are connected to.
-    # +soc+ is the tcp socket we are bound to.  +config+ is our
-    # configuration.
-    def initialize(uri, soc, config={})
-      @uri = uri
-      @socket = soc
-      @config = config
-      @acl = config[:tcp_acl]
-      @msg = DRbMessage.new(config)
-      set_sockopt(@socket)
-    end
-
-    # Get the URI that we are connected to.
-    attr_reader :uri
-
-    # Get the address of our TCP peer (the other end of the socket
-    # we are bound to.
-    def peeraddr
-      @socket.peeraddr
-    end
-
-    # Get the socket.
-    def stream; @socket; end
-
-    # On the client side, send a request to the server.
-    def send_request(ref, msg_id, arg, b)
-      @msg.send_request(stream, ref, msg_id, arg, b)
-    end
-
-    # On the server side, receive a request from the client.
-    def recv_request
-      @msg.recv_request(stream)
-    end
-
-    # On the server side, send a reply to the client.
-    def send_reply(succ, result)
-      @msg.send_reply(stream, succ, result)
-    end
-
-    # On the client side, receive a reply from the server.
-    def recv_reply
-      @msg.recv_reply(stream)
-    end
-
-    public
-
-    # Close the connection.
-    #
-    # If this is an instance returned by #open_server, then this stops
-    # listening for new connections altogether.  If this is an instance
-    # returned by #open or by #accept, then it closes this particular
-    # client-server session.
-    def close
-      if @socket
-        @socket.close
-        @socket = nil
-      end
-    end
-
-    # On the server side, for an instance returned by #open_server,
-    # accept a client connection and return a new instance to handle
-    # the server's side of this client-server session.
-    def accept
-      while true
-        s = @socket.accept
-        break if (@acl ? @acl.allow_socket?(s) : true)
-        s.close
-      end
-      if @config[:tcp_original_host].to_s.size == 0
-        uri = "druby://#{s.addr[3]}:#{@config[:tcp_port]}"
-      else
-        uri = @uri
-      end
-      self.class.new(uri, s, @config)
-    end
-
-    # Check to see if this connection is alive.
-    def alive?
-      return false unless @socket
-      if IO.select([@socket], nil, nil, 0)
-        close
-        return false
-      end
-      true
-    end
-
-    def set_sockopt(soc) # :nodoc:
-      soc.setsockopt(Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1)
-      soc.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC) if defined? Fcntl::FD_CLOEXEC
-    end
-  end
-
-  module DRbProtocol
-    @protocol = [DRbTCPSocket] # default
-  end
-
-  class DRbURIOption  # :nodoc:  I don't understand the purpose of this class...
-    def initialize(option)
-      @option = option.to_s
-    end
-    attr :option
-    def to_s; @option; end
-
-    def ==(other)
-      return false unless DRbURIOption === other
-      @option == other.option
-    end
-
-    def hash
-      @option.hash
-    end
-
-    alias eql? ==
-  end
-
-  # Object wrapping a reference to a remote drb object.
-  #
-  # Method calls on this object are relayed to the remote
-  # object that this object is a stub for.
-  class DRbObject
-
-    # Unmarshall a marshalled DRbObject.
-    #
-    # If the referenced object is located within the local server, then
-    # the object itself is returned.  Otherwise, a new DRbObject is
-    # created to act as a stub for the remote referenced object.
-    def self._load(s)
-      uri, ref = Marshal.load(s)
-
-      if DRb.here?(uri)
-        obj = DRb.to_obj(ref)
-        if ((! obj.tainted?) && Thread.current[:drb_untaint])
-          Thread.current[:drb_untaint].push(obj)
-        end
-        return obj
-      end
-
-      self.new_with(uri, ref)
-    end
-
-    def self.new_with(uri, ref)
-      it = self.allocate
-      it.instance_variable_set('@uri', uri)
-      it.instance_variable_set('@ref', ref)
-      it
-    end
-
-    # Create a new DRbObject from a URI alone.
-    def self.new_with_uri(uri)
-      self.new(nil, uri)
-    end
-
-    # Marshall this object.
-    #
-    # The URI and ref of the object are marshalled.
-    def _dump(lv)
-      Marshal.dump([@uri, @ref])
-    end
-
-    # Create a new remote object stub.
-    #
-    # +obj+ is the (local) object we want to create a stub for.  Normally
-    # this is +nil+.  +uri+ is the URI of the remote object that this
-    # will be a stub for.
-    def initialize(obj, uri=nil)
-      @uri = nil
-      @ref = nil
-      if obj.nil?
-        return if uri.nil?
-        @uri, option = DRbProtocol.uri_option(uri, DRb.config)
-        @ref = DRbURIOption.new(option) unless option.nil?
-      else
-        @uri = uri ? uri : (DRb.uri rescue nil)
-        @ref = obj ? DRb.to_id(obj) : nil
-      end
-    end
-
-    # Get the URI of the remote object.
-    def __drburi
-      @uri
-    end
-
-    # Get the reference of the object, if local.
-    def __drbref
-      @ref
-    end
-
-    undef :to_s
-    undef :to_a if respond_to?(:to_a)
-
-    def respond_to?(msg_id, priv=false)
-      case msg_id
-      when :_dump
-        true
-      when :marshal_dump
-        false
-      else
-        method_missing(:respond_to?, msg_id, priv)
-      end
-    end
-
-    # Routes method calls to the referenced object.
-    def method_missing(msg_id, *a, &b)
-      if DRb.here?(@uri)
-        obj = DRb.to_obj(@ref)
-        DRb.current_server.check_insecure_method(obj, msg_id)
-        return obj.__send__(msg_id, *a, &b)
-      end
-
-      succ, result = self.class.with_friend(@uri) do
-        DRbConn.open(@uri) do |conn|
-          conn.send_message(self, msg_id, a, b)
-        end
-      end
-
-      if succ
-        return result
-      elsif DRbUnknown === result
-        raise result
-      else
-        bt = self.class.prepare_backtrace(@uri, result)
-        result.set_backtrace(bt + caller)
-        raise result
-      end
-    end
-
-    def self.with_friend(uri)
-      friend = DRb.fetch_server(uri)
-      return yield() unless friend
-
-      save = Thread.current['DRb']
-      Thread.current['DRb'] = { 'server' => friend }
-      return yield
-    ensure
-      Thread.current['DRb'] = save if friend
-    end
-
-    def self.prepare_backtrace(uri, result)
-      prefix = "(#{uri}) "
-      bt = []
-      result.backtrace.each do |x|
-        break if /`__send__'$/ =~ x
-        if /^\(druby:\/\// =~ x
-          bt.push(x)
-        else
-          bt.push(prefix + x)
-        end
-      end
-      bt
-    end
-
-    def pretty_print(q)   # :nodoc:
-      q.pp_object(self)
-    end
-
-    def pretty_print_cycle(q)   # :nodoc:
-      q.object_address_group(self) {
-        q.breakable
-        q.text '...'
-      }
-    end
-  end
-
-  # Class handling the connection between a DRbObject and the
-  # server the real object lives on.
-  #
-  # This class maintains a pool of connections, to reduce the
-  # overhead of starting and closing down connections for each
-  # method call.
-  #
-  # This class is used internally by DRbObject.  The user does
-  # not normally need to deal with it directly.
-  class DRbConn
-    POOL_SIZE = 16  # :nodoc:
-    @mutex = Mutex.new
-    @pool = []
-
-    def self.open(remote_uri)  # :nodoc:
-      begin
-        conn = nil
-
-        @mutex.synchronize do
-          #FIXME
-          new_pool = []
-          @pool.each do |c|
-            if conn.nil? and c.uri == remote_uri
-              conn = c if c.alive?
-            else
-              new_pool.push c
-            end
-          end
-          @pool = new_pool
-        end
-
-        conn = self.new(remote_uri) unless conn
-        succ, result = yield(conn)
-        return succ, result
-
-      ensure
-        if conn
-          if succ
-            @mutex.synchronize do
-              @pool.unshift(conn)
-              @pool.pop.close while @pool.size > POOL_SIZE
-            end
-          else
-            conn.close
-          end
-        end
-      end
-    end
-
-    def initialize(remote_uri)  # :nodoc:
-      @uri = remote_uri
-      @protocol = DRbProtocol.open(remote_uri, DRb.config)
-    end
-    attr_reader :uri  # :nodoc:
-
-    def send_message(ref, msg_id, arg, block)  # :nodoc:
-      @protocol.send_request(ref, msg_id, arg, block)
-      @protocol.recv_reply
-    end
-
-    def close  # :nodoc:
-      @protocol.close
-      @protocol = nil
-    end
-
-    def alive?  # :nodoc:
-      return false unless @protocol
-      @protocol.alive?
-    end
-  end
-
-  # Class representing a drb server instance.
-  #
-  # A DRbServer must be running in the local process before any incoming
-  # dRuby calls can be accepted, or any local objects can be passed as
-  # dRuby references to remote processes, even if those local objects are
-  # never actually called remotely. You do not need to start a DRbServer
-  # in the local process if you are only making outgoing dRuby calls
-  # passing marshalled parameters.
-  #
-  # Unless multiple servers are being used, the local DRbServer is normally
-  # started by calling DRb.start_service.
-  class DRbServer
-    @@acl = nil
-    @@idconv = DRbIdConv.new
-    @@secondary_server = nil
-    @@argc_limit = 256
-    @@load_limit = 256 * 102400
-    @@verbose = false
-    @@safe_level = 0
-
-    # Set the default value for the :argc_limit option.
-    #
-    # See #new().  The initial default value is 256.
-    def self.default_argc_limit(argc)
-      @@argc_limit = argc
-    end
-
-    # Set the default value for the :load_limit option.
-    #
-    # See #new().  The initial default value is 25 MB.
-    def self.default_load_limit(sz)
-      @@load_limit = sz
-    end
-
-    # Set the default value for the :acl option.
-    #
-    # See #new().  The initial default value is nil.
-    def self.default_acl(acl)
-      @@acl = acl
-    end
-
-    # Set the default value for the :id_conv option.
-    #
-    # See #new().  The initial default value is a DRbIdConv instance.
-    def self.default_id_conv(idconv)
-      @@idconv = idconv
-    end
-
-    def self.default_safe_level(level)
-      @@safe_level = level
-    end
-
-    # Set the default value of the :verbose option.
-    #
-    # See #new().  The initial default value is false.
-    def self.verbose=(on)
-      @@verbose = on
-    end
-
-    # Get the default value of the :verbose option.
-    def self.verbose
-      @@verbose
-    end
-
-    def self.make_config(hash={})  # :nodoc:
-      default_config = {
-        :idconv => @@idconv,
-        :verbose => @@verbose,
-        :tcp_acl => @@acl,
-        :load_limit => @@load_limit,
-        :argc_limit => @@argc_limit,
-        :safe_level => @@safe_level
-      }
-      default_config.update(hash)
-    end
-
-    # Create a new DRbServer instance.
-    #
-    # +uri+ is the URI to bind to.  This is normally of the form
-    # 'druby://<hostname>:<port>' where <hostname> is a hostname of
-    # the local machine.  If nil, then the system's default hostname
-    # will be bound to, on a port selected by the system; these value
-    # can be retrieved from the +uri+ attribute.  'druby:' specifies
-    # the default dRuby transport protocol: another protocol, such
-    # as 'drbunix:', can be specified instead.
-    #
-    # +front+ is the front object for the server, that is, the object
-    # to which remote method calls on the server will be passed.  If
-    # nil, then the server will not accept remote method calls.
-    #
-    # If +config_or_acl+ is a hash, it is the configuration to
-    # use for this server.  The following options are recognised:
-    #
-    # :idconv :: an id-to-object conversion object.  This defaults
-    #            to an instance of the class DRb::DRbIdConv.
-    # :verbose :: if true, all unsuccessful remote calls on objects
-    #             in the server will be logged to $stdout. false
-    #             by default.
-    # :tcp_acl :: the access control list for this server.  See
-    #             the ACL class from the main dRuby distribution.
-    # :load_limit :: the maximum message size in bytes accepted by
-    #                the server.  Defaults to 25 MB (26214400).
-    # :argc_limit :: the maximum number of arguments to a remote
-    #                method accepted by the server.  Defaults to
-    #                256.
-    #
-    # The default values of these options can be modified on
-    # a class-wide basis by the class methods #default_argc_limit,
-    # #default_load_limit, #default_acl, #default_id_conv,
-    # and #verbose=
-    #
-    # If +config_or_acl+ is not a hash, but is not nil, it is
-    # assumed to be the access control list for this server.
-    # See the :tcp_acl option for more details.
-    #
-    # If no other server is currently set as the primary server,
-    # this will become the primary server.
-    #
-    # The server will immediately start running in its own thread.
-    def initialize(uri=nil, front=nil, config_or_acl=nil)
-      if Hash === config_or_acl
-        config = config_or_acl.dup
-      else
-        acl = config_or_acl || @@acl
-        config = {
-          :tcp_acl => acl
-        }
-      end
-
-      @config = self.class.make_config(config)
-
-      @protocol = DRbProtocol.open_server(uri, @config)
-      @uri = @protocol.uri
-      @exported_uri = [@uri]
-
-      @front = front
-      @idconv = @config[:idconv]
-      @safe_level = @config[:safe_level]
-
-      @grp = ThreadGroup.new
-      @thread = run
-
-      DRb.regist_server(self)
-    end
-
-    # The URI of this DRbServer.
-    attr_reader :uri
-
-    # The main thread of this DRbServer.
-    #
-    # This is the thread that listens for and accepts connections
-    # from clients, not that handles each client's request-response
-    # session.
-    attr_reader :thread
-
-    # The front object of the DRbServer.
-    #
-    # This object receives remote method calls made on the server's
-    # URI alone, with an object id.
-    attr_reader :front
-
-    # The configuration of this DRbServer
-    attr_reader :config
-
-    attr_reader :safe_level
-
-    # Set whether to operate in verbose mode.
-    #
-    # In verbose mode, failed calls are logged to stdout.
-    def verbose=(v); @config[:verbose]=v; end
-
-    # Get whether the server is in verbose mode.
-    #
-    # In verbose mode, failed calls are logged to stdout.
-    def verbose; @config[:verbose]; end
-
-    # Is this server alive?
-    def alive?
-      @thread.alive?
-    end
-    
-    def here?(uri)
-      @exported_uri.include?(uri)
-    end
-
-    # Stop this server.
-    def stop_service
-      DRb.remove_server(self)
-      if  Thread.current['DRb'] && Thread.current['DRb']['server'] == self
-        Thread.current['DRb']['stop_service'] = true
-      else
-        @thread.kill.join
-      end
-    end
-
-    # Convert a dRuby reference to the local object it refers to.
-    def to_obj(ref)
-      return front if ref.nil?
-      return front[ref.to_s] if DRbURIOption === ref
-      @idconv.to_obj(ref)
-    end
-
-    # Convert a local object to a dRuby reference.
-    def to_id(obj)
-      return nil if obj.__id__ == front.__id__
-      @idconv.to_id(obj)
-    end
-
-    private
-    def run
-      Thread.start do
-        begin
-          while true
-            main_loop
-          end
-        ensure
-          @protocol.close if @protocol
-        end
-      end
-    end
-
-    # List of insecure methods.
-    #
-    # These methods are not callable via dRuby.
-    INSECURE_METHOD = [
-      :__send__
-    ]
-
-    # Has a method been included in the list of insecure methods?
-    def insecure_method?(msg_id)
-      INSECURE_METHOD.include?(msg_id)
-    end
-
-    # Coerce an object to a string, providing our own representation if
-    # to_s is not defined for the object.
-    def any_to_s(obj)
-      obj.to_s + ":#{obj.class}"
-    rescue
-      sprintf("#<%s:0x%lx>", obj.class, obj.__id__)
-    end
-
-    # Check that a method is callable via dRuby.
-    #
-    # +obj+ is the object we want to invoke the method on. +msg_id+ is the
-    # method name, as a Symbol.
-    #
-    # If the method is an insecure method (see #insecure_method?) a
-    # SecurityError is thrown.  If the method is private or undefined,
-    # a NameError is thrown.
-    def check_insecure_method(obj, msg_id)
-      return true if Proc === obj && msg_id == :__drb_yield
-      raise(ArgumentError, "#{any_to_s(msg_id)} is not a symbol") unless Symbol == msg_id.class
-      raise(SecurityError, "insecure method `#{msg_id}'") if insecure_method?(msg_id)
-
-      if obj.private_methods.include?(msg_id)
-        desc = any_to_s(obj)
-        raise NoMethodError, "private method `#{msg_id}' called for #{desc}"
-      elsif obj.protected_methods.include?(msg_id)
-        desc = any_to_s(obj)
-        raise NoMethodError, "protected method `#{msg_id}' called for #{desc}"
-      else
-        true
-      end
-    end
-    public :check_insecure_method
-
-    class InvokeMethod  # :nodoc:
-      def initialize(drb_server, client)
-        @drb_server = drb_server
-        @safe_level = drb_server.safe_level
-        @client = client
-      end
-
-      def perform
-        @result = nil
-        @succ = false
-        setup_message
-
-        if $SAFE < @safe_level
-          info = Thread.current['DRb']
-          if @block
-            @result = Thread.new {
-              Thread.current['DRb'] = info
-              $SAFE = @safe_level
-              perform_with_block
-            }.value
-          else
-            @result = Thread.new {
-              Thread.current['DRb'] = info
-              $SAFE = @safe_level
-              perform_without_block
-            }.value
-          end
-        else
-          if @block
-            @result = perform_with_block
-          else
-            @result = perform_without_block
-          end
-        end
-        @succ = true
-        if @msg_id == :to_ary && @result.class == Array
-          @result = DRbArray.new(@result)
-        end
-        return @succ, @result
-      rescue StandardError, ScriptError, Interrupt
-        @result = $!
-        return @succ, @result
-      end
-
-      private
-      def init_with_client
-        obj, msg, argv, block = @client.recv_request
-        @obj = obj
-        @msg_id = msg.intern
-        @argv = argv
-        @block = block
-      end
-
-      def check_insecure_method
-        @drb_server.check_insecure_method(@obj, @msg_id)
-      end
-
-      def setup_message
-        init_with_client
-        check_insecure_method
-      end
-
-      def perform_without_block
-        if Proc === @obj && @msg_id == :__drb_yield
-          if @argv.size == 1
-            ary = @argv
-          else
-            ary = [@argv]
-          end
-          ary.collect(&@obj)[0]
-        else
-          @obj.__send__(@msg_id, *@argv)
-        end
-      end
-
-    end
-
-    if RUBY_VERSION >= '1.8'
-      require 'drb/invokemethod'
-      class InvokeMethod
-        include InvokeMethod18Mixin
-      end
-    else
-      require 'drb/invokemethod16'
-      class InvokeMethod
-        include InvokeMethod16Mixin
-      end
-    end
-
-    # The main loop performed by a DRbServer's internal thread.
-    #
-    # Accepts a connection from a client, and starts up its own
-    # thread to handle it.  This thread loops, receiving requests
-    # from the client, invoking them on a local object, and
-    # returning responses, until the client closes the connection
-    # or a local method call fails.
-    def main_loop
-      Thread.start(@protocol.accept) do |client|
-        @grp.add Thread.current
-        Thread.current['DRb'] = { 'client' => client ,
-                                  'server' => self }
-        DRb.mutex.synchronize do
-          client_uri = client.uri
-          @exported_uri << client_uri unless @exported_uri.include?(client_uri)
-        end
-        loop do
-          begin
-            succ = false
-            invoke_method = InvokeMethod.new(self, client)
-            succ, result = invoke_method.perform
-            if !succ && verbose
-              p result
-              result.backtrace.each do |x|
-                puts x
-              end
-            end
-            client.send_reply(succ, result) rescue nil
-          ensure
-            client.close unless succ
-            if Thread.current['DRb']['stop_service']
-              Thread.new { stop_service }
-            end
-            break unless succ
-          end
-        end
-      end
-    end
-  end
-
-  @primary_server = nil
-
-  # Start a dRuby server locally.
-  #
-  # The new dRuby server will become the primary server, even
-  # if another server is currently the primary server.
-  #
-  # +uri+ is the URI for the server to bind to.  If nil,
-  # the server will bind to random port on the default local host
-  # name and use the default dRuby protocol.
-  #
-  # +front+ is the server's front object.  This may be nil.
-  #
-  # +config+ is the configuration for the new server.  This may
-  # be nil.
-  #
-  # See DRbServer::new.
-  def start_service(uri=nil, front=nil, config=nil)
-    @primary_server = DRbServer.new(uri, front, config)
-  end
-  module_function :start_service
-
-  # The primary local dRuby server.
-  #
-  # This is the server created by the #start_service call.
-  attr_accessor :primary_server
-  module_function :primary_server=, :primary_server
-
-  # Get the 'current' server.
-  #
-  # In the context of execution taking place within the main
-  # thread of a dRuby server (typically, as a result of a remote
-  # call on the server or one of its objects), the current
-  # server is that server.  Otherwise, the current server is
-  # the primary server.
-  #
-  # If the above rule fails to find a server, a DRbServerNotFound
-  # error is raised.
-  def current_server
-    drb = Thread.current['DRb']
-    server = (drb && drb['server']) ? drb['server'] : @primary_server
-    raise DRbServerNotFound unless server
-    return server
-  end
-  module_function :current_server
-
-  # Stop the local dRuby server.
-  #
-  # This operates on the primary server.  If there is no primary
-  # server currently running, it is a noop.
-  def stop_service
-    @primary_server.stop_service if @primary_server
-    @primary_server = nil
-  end
-  module_function :stop_service
-
-  # Get the URI defining the local dRuby space.
-  #
-  # This is the URI of the current server.  See #current_server.
-  def uri
-    drb = Thread.current['DRb']
-    client = (drb && drb['client'])
-    if client
-      uri = client.uri
-      return uri if uri
-    end
-    current_server.uri
-  end
-  module_function :uri
-
-  # Is +uri+ the URI for the current local server?
-  def here?(uri)
-    current_server.here?(uri) rescue false
-    # (current_server.uri rescue nil) == uri
-  end
-  module_function :here?
-
-  # Get the configuration of the current server.
-  #
-  # If there is no current server, this returns the default configuration.
-  # See #current_server and DRbServer::make_config.
-  def config
-    current_server.config
-  rescue
-    DRbServer.make_config
-  end
-  module_function :config
-
-  # Get the front object of the current server.
-  #
-  # This raises a DRbServerNotFound error if there is no current server.
-  # See #current_server.
-  def front
-    current_server.front
-  end
-  module_function :front
-
-  # Convert a reference into an object using the current server.
-  #
-  # This raises a DRbServerNotFound error if there is no current server.
-  # See #current_server.
-  def to_obj(ref)
-    current_server.to_obj(ref)
-  end
-
-  # Get a reference id for an object using the current server.
-  #
-  # This raises a DRbServerNotFound error if there is no current server.
-  # See #current_server.
-  def to_id(obj)
-    current_server.to_id(obj)
-  end
-  module_function :to_id
-  module_function :to_obj
-
-  # Get the thread of the primary server.
-  #
-  # This returns nil if there is no primary server.  See #primary_server.
-  def thread
-    @primary_server ? @primary_server.thread : nil
-  end
-  module_function :thread
-
-  # Set the default id conv object.
-  #
-  # See DRbServer#default_id_conv.
-  def install_id_conv(idconv)
-    DRbServer.default_id_conv(idconv)
-  end
-  module_function :install_id_conv
-
-  # Set the default acl.
-  #
-  # See DRb::DRbServer.default_acl.
-  def install_acl(acl)
-    DRbServer.default_acl(acl)
-  end
-  module_function :install_acl
-
-  @mutex = Mutex.new
-  def mutex
-    @mutex
-  end
-  module_function :mutex
-
-  @server = {}
-  def regist_server(server)
-    @server[server.uri] = server
-    mutex.synchronize do
-      @primary_server = server unless @primary_server
-    end
-  end
-  module_function :regist_server
-
-  def remove_server(server)
-    @server.delete(server.uri)
-  end
-  module_function :remove_server
-
-  def fetch_server(uri)
-    @server[uri]
-  end
-  module_function :fetch_server
-end
-
-# :stopdoc:
-DRbObject = DRb::DRbObject
-DRbUndumped = DRb::DRbUndumped
-DRbIdConv = DRb::DRbIdConv
diff --git a/lib/drb/eq.rb b/lib/drb/eq.rb
deleted file mode 100644
index 6328c81202..0000000000
--- a/lib/drb/eq.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-module DRb
-  class DRbObject
-    def ==(other)
-      return false unless DRbObject === other
-     (@ref == other.__drbref) && (@uri == other.__drburi)
-    end
-
-    def hash
-      [@uri, @ref].hash
-    end
-
-    alias eql? ==
-  end
-end
diff --git a/lib/drb/extserv.rb b/lib/drb/extserv.rb
deleted file mode 100644
index bb11211cd1..0000000000
--- a/lib/drb/extserv.rb
+++ /dev/null
@@ -1,71 +0,0 @@
-=begin
- external service
-        Copyright (c) 2000,2002 Masatoshi SEKI
-=end
-
-require 'drb/drb'
-require 'monitor'
-
-module DRb
-  class ExtServ
-    include MonitorMixin
-    include DRbUndumped
-
-    def initialize(there, name, server=nil)
-      super()
-      @server = server || DRb::primary_server
-      @name = name
-      ro = DRbObject.new(nil, there)
-      synchronize do
-        @invoker = ro.regist(name, DRbObject.new(self, @server.uri))
-      end
-    end
-    attr_reader :server
-
-    def front
-      DRbObject.new(nil, @server.uri)
-    end
-
-    def stop_service
-      synchronize do
-        @invoker.unregist(@name)
-        server = @server
-        @server = nil
-        server.stop_service
-        true
-      end
-    end
-
-    def alive?
-      @server ? @server.alive? : false
-    end
-  end
-end
-
-if __FILE__ == $0
-  class Foo
-    include DRbUndumped
-
-    def initialize(str)
-      @str = str
-    end
-
-    def hello(it)
-      "#{it}: #{self}"
-    end
-
-    def to_s
-      @str
-    end
-  end
-
-  cmd = ARGV.shift
-  case cmd
-  when 'itest1', 'itest2'
-    front = Foo.new(cmd)
-    manager = DRb::DRbServer.new(nil, front)
-    es = DRb::ExtServ.new(ARGV.shift, ARGV.shift, manager)
-    es.server.thread.join
-  end
-end
-
diff --git a/lib/drb/extservm.rb b/lib/drb/extservm.rb
deleted file mode 100644
index 8a7fc316af..0000000000
--- a/lib/drb/extservm.rb
+++ /dev/null
@@ -1,93 +0,0 @@
-=begin
- external service manager
-        Copyright (c) 2000 Masatoshi SEKI
-=end
-
-require 'drb/drb'
-require 'thread'
-require 'monitor'
-
-module DRb
-  class ExtServManager
-    include DRbUndumped
-    include MonitorMixin
-
-    @@command = {}
-
-    def self.command
-      @@command
-    end
-
-    def self.command=(cmd)
-      @@command = cmd
-    end
-
-    def initialize
-      super()
-      @cond = new_cond
-      @servers = {}
-      @waiting = []
-      @queue = Queue.new
-      @thread = invoke_thread
-      @uri = nil
-    end
-    attr_accessor :uri
-
-    def service(name)
-      synchronize do
-        while true
-          server = @servers[name]
-          return server if server && server.alive?
-          invoke_service(name)
-          @cond.wait
-        end
-      end
-    end
-
-    def regist(name, ro)
-      synchronize do
-        @servers[name] = ro
-        @cond.signal
-      end
-      self
-    end
-
-    def unregist(name)
-      synchronize do
-        @servers.delete(name)
-      end
-    end
-
-    private
-    def invoke_thread
-      Thread.new do
-        while true
-          name = @queue.pop
-          invoke_service_command(name, @@command[name])
-        end
-      end
-    end
-
-    def invoke_service(name)
-      @queue.push(name)
-    end
-
-    def invoke_service_command(name, command)
-      raise "invalid command. name: #{name}" unless command
-      synchronize do
-        return if @servers.include?(name)
-        @servers[name] = false
-      end
-      uri = @uri || DRb.uri
-      if command.respond_to? :to_ary
-        command = command.to_ary + [uri, name]
-        pid = spawn(*command)
-      else
-        pid = spawn("#{command} #{uri} #{name}")
-      end
-      th = Process.detach(pid)
-      th[:drb_service] = name
-      th
-    end
-  end
-end
diff --git a/lib/drb/gw.rb b/lib/drb/gw.rb
deleted file mode 100644
index b7a5f5383f..0000000000
--- a/lib/drb/gw.rb
+++ /dev/null
@@ -1,122 +0,0 @@
-require 'drb/drb'
-require 'monitor'
-
-module DRb
-  class GWIdConv < DRbIdConv
-    def to_obj(ref)
-      if Array === ref && ref[0] == :DRbObject
-        return DRbObject.new_with(ref[1], ref[2])
-      end
-      super(ref)
-    end
-  end
-
-  class GW
-    include MonitorMixin
-    def initialize
-      super()
-      @hash = {}
-    end
-
-    def [](key)
-      synchronize do
-        @hash[key]
-      end
-    end
-
-    def []=(key, v)
-      synchronize do
-        @hash[key] = v
-      end
-    end
-  end
-
-  class DRbObject
-    def self._load(s)
-      uri, ref = Marshal.load(s)
-      if DRb.uri == uri
-        return ref ? DRb.to_obj(ref) : DRb.front
-      end
-
-      self.new_with(DRb.uri, [:DRbObject, uri, ref])
-    end
-
-    def _dump(lv)
-      if DRb.uri == @uri
-        if Array === @ref && @ref[0] == :DRbObject
-          Marshal.dump([@ref[1], @ref[2]])
-        else
-          Marshal.dump([@uri, @ref]) # ??
-        end
-      else
-        Marshal.dump([DRb.uri, [:DRbObject, @uri, @ref]])
-      end
-    end
-  end
-end
-
-=begin
-DRb.install_id_conv(DRb::GWIdConv.new)
-
-front = DRb::GW.new
-
-s1 = DRb::DRbServer.new('drbunix:/tmp/gw_b_a', front)
-s2 = DRb::DRbServer.new('drbunix:/tmp/gw_b_c', front)
-
-s1.thread.join
-s2.thread.join
-=end
-
-=begin
-# foo.rb
-
-require 'drb/drb'
-
-class Foo
-  include DRbUndumped
-  def initialize(name, peer=nil)
-    @name = name
-    @peer = peer
-  end
-
-  def ping(obj)
-    puts "#{@name}: ping: #{obj.inspect}"
-    @peer.ping(self) if @peer
-  end
-end
-=end
-
-=begin
-# gw_a.rb
-require 'drb/unix'
-require 'foo'
-
-obj = Foo.new('a')
-DRb.start_service("drbunix:/tmp/gw_a", obj)
-
-robj = DRbObject.new_with_uri('drbunix:/tmp/gw_b_a')
-robj[:a] = obj
-
-DRb.thread.join
-=end
-
-=begin
-# gw_c.rb
-require 'drb/unix'
-require 'foo'
-
-foo = Foo.new('c', nil)
-
-DRb.start_service("drbunix:/tmp/gw_c", nil)
-
-robj = DRbObject.new_with_uri("drbunix:/tmp/gw_b_c")
-
-puts "c->b"
-a = robj[:a]
-sleep 2
-
-a.ping(foo)
-
-DRb.thread.join
-=end
-
diff --git a/lib/drb/invokemethod.rb b/lib/drb/invokemethod.rb
deleted file mode 100644
index 353dbd00d8..0000000000
--- a/lib/drb/invokemethod.rb
+++ /dev/null
@@ -1,34 +0,0 @@
-# for ruby-1.8.0
-
-module DRb
-  class DRbServer
-    module InvokeMethod18Mixin
-      def block_yield(x)
-        if x.size == 1 && x[0].class == Array
-          x[0] = DRbArray.new(x[0])
-        end
-        @block.call(*x)
-      end
-
-      def perform_with_block
-        @obj.__send__(@msg_id, *@argv) do |*x|
-          jump_error = nil
-          begin
-            block_value = block_yield(x)
-          rescue LocalJumpError
-            jump_error = $!
-          end
-          if jump_error
-            case jump_error.reason
-            when :break
-              break(jump_error.exit_value)
-            else
-              raise jump_error
-            end
-          end
-          block_value
-        end
-      end
-    end
-  end
-end
diff --git a/lib/drb/observer.rb b/lib/drb/observer.rb
deleted file mode 100644
index 149426db7b..0000000000
--- a/lib/drb/observer.rb
+++ /dev/null
@@ -1,22 +0,0 @@
-require 'observer'
-
-module DRb
-  module DRbObservable
-    include Observable
-
-    def notify_observers(*arg)
-      if defined? @observer_state and @observer_state
-        if defined? @observer_peers
-          @observer_peers.each do |observer, method|
-            begin
-              observer.send(method, *arg)
-            rescue
-              delete_observer(observer)
-            end
-          end
-        end
-        @observer_state = false
-      end
-    end
-  end
-end
diff --git a/lib/drb/ssl.rb b/lib/drb/ssl.rb
deleted file mode 100644
index a680594d80..0000000000
--- a/lib/drb/ssl.rb
+++ /dev/null
@@ -1,195 +0,0 @@
-require 'socket'
-require 'openssl'
-require 'drb/drb'
-require 'singleton'
-
-module DRb
-
-  class DRbSSLSocket < DRbTCPSocket
-
-    class SSLConfig
-
-      DEFAULT = {
-        :SSLCertificate       => nil,
-        :SSLPrivateKey        => nil,
-        :SSLClientCA          => nil,
-        :SSLCACertificatePath => nil,
-        :SSLCACertificateFile => nil,
-        :SSLVerifyMode        => ::OpenSSL::SSL::VERIFY_NONE,
-        :SSLVerifyDepth       => nil,
-        :SSLVerifyCallback    => nil,   # custom verification
-        :SSLCertificateStore  => nil,
-        # Must specify if you use auto generated certificate.
-        :SSLCertName          => nil,   # e.g. [["CN","fqdn.example.com"]]
-        :SSLCertComment       => "Generated by Ruby/OpenSSL"
-      }
-
-      def initialize(config)
-        @config  = config
-        @cert    = config[:SSLCertificate]
-        @pkey    = config[:SSLPrivateKey]
-        @ssl_ctx = nil
-      end
-
-      def [](key);
-        @config[key] || DEFAULT[key]
-      end
-
-      def connect(tcp)
-        ssl = ::OpenSSL::SSL::SSLSocket.new(tcp, @ssl_ctx)
-        ssl.sync = true
-        ssl.connect
-        ssl
-      end
-
-      def accept(tcp)
-        ssl = OpenSSL::SSL::SSLSocket.new(tcp, @ssl_ctx)
-        ssl.sync = true
-        ssl.accept
-        ssl
-      end
-
-      def setup_certificate
-        if @cert && @pkey
-          return
-        end
-
-        rsa = OpenSSL::PKey::RSA.new(1024){|p, n|
-          next unless self[:verbose]
-          case p
-          when 0; $stderr.putc "."  # BN_generate_prime
-          when 1; $stderr.putc "+"  # BN_generate_prime
-          when 2; $stderr.putc "*"  # searching good prime,
-                                    # n = #of try,
-                                    # but also data from BN_generate_prime
-          when 3; $stderr.putc "\n" # found good prime, n==0 - p, n==1 - q,
-                                    # but also data from BN_generate_prime
-          else;   $stderr.putc "*"  # BN_generate_prime
-          end
-        }
-
-        cert = OpenSSL::X509::Certificate.new
-        cert.version = 3
-        cert.serial = 0
-        name = OpenSSL::X509::Name.new(self[:SSLCertName])
-        cert.subject = name
-        cert.issuer = name
-        cert.not_before = Time.now
-        cert.not_after = Time.now + (365*24*60*60)
-        cert.public_key = rsa.public_key
-
-        ef = OpenSSL::X509::ExtensionFactory.new(nil,cert)
-        cert.extensions = [
-          ef.create_extension("basicConstraints","CA:FALSE"),
-          ef.create_extension("subjectKeyIdentifier", "hash") ]
-        ef.issuer_certificate = cert
-        cert.add_extension(ef.create_extension("authorityKeyIdentifier",
-                                               "keyid:always,issuer:always"))
-        if comment = self[:SSLCertComment]
-          cert.add_extension(ef.create_extension("nsComment", comment))
-        end
-        cert.sign(rsa, OpenSSL::Digest::SHA1.new)
-
-        @cert = cert
-        @pkey = rsa
-      end
-
-      def setup_ssl_context
-        ctx = ::OpenSSL::SSL::SSLContext.new
-        ctx.cert            = @cert
-        ctx.key             = @pkey
-        ctx.client_ca       = self[:SSLClientCA]
-        ctx.ca_path         = self[:SSLCACertificatePath]
-        ctx.ca_file         = self[:SSLCACertificateFile]
-        ctx.verify_mode     = self[:SSLVerifyMode]
-        ctx.verify_depth    = self[:SSLVerifyDepth]
-        ctx.verify_callback = self[:SSLVerifyCallback]
-        ctx.cert_store      = self[:SSLCertificateStore]
-        @ssl_ctx = ctx
-      end
-    end
-
-    def self.parse_uri(uri)
-      if uri =~ /^drbssl:\/\/(.*?):(\d+)(\?(.*))?$/
-        host = $1
-        port = $2.to_i
-        option = $4
-        [host, port, option]
-      else
-        raise(DRbBadScheme, uri) unless uri =~ /^drbssl:/
-        raise(DRbBadURI, 'can\'t parse uri:' + uri)
-      end
-    end
-
-    def self.open(uri, config)
-      host, port, = parse_uri(uri)
-      host.untaint
-      port.untaint
-      soc = TCPSocket.open(host, port)
-      ssl_conf = SSLConfig::new(config)
-      ssl_conf.setup_ssl_context
-      ssl = ssl_conf.connect(soc)
-      self.new(uri, ssl, ssl_conf, true)
-    end
-
-    def self.open_server(uri, config)
-      uri = 'drbssl://:0' unless uri
-      host, port, = parse_uri(uri)
-      if host.size == 0
-        host = getservername
-        soc = open_server_inaddr_any(host, port)
-      else
-        soc = TCPServer.open(host, port)
-      end
-      port = soc.addr[1] if port == 0
-      @uri = "drbssl://#{host}:#{port}"
-
-      ssl_conf = SSLConfig.new(config)
-      ssl_conf.setup_certificate
-      ssl_conf.setup_ssl_context
-      self.new(@uri, soc, ssl_conf, false)
-    end
-
-    def self.uri_option(uri, config)
-      host, port, option = parse_uri(uri)
-      return "drbssl://#{host}:#{port}", option
-    end
-
-    def initialize(uri, soc, config, is_established)
-      @ssl = is_established ? soc : nil
-      super(uri, soc.to_io, config)
-    end
-
-    def stream; @ssl; end
-
-    def close
-      if @ssl
-        @ssl.close
-        @ssl = nil
-      end
-      super
-    end
-
-    def accept
-      begin
-      while true
-        soc = @socket.accept
-        break if (@acl ? @acl.allow_socket?(soc) : true)
-        soc.close
-      end
-      begin
-	ssl = @config.accept(soc)
-      rescue Exception
-        soc.close
-        raise
-      end
-      self.class.new(uri, ssl, @config, true)
-      rescue OpenSSL::SSL::SSLError
-        warn("#{__FILE__}:#{__LINE__}: warning: #{$!.message} (#{$!.class})") if @config[:verbose]
-        retry
-      end
-    end
-  end
-
-  DRbProtocol.add_protocol(DRbSSLSocket)
-end
diff --git a/lib/drb/timeridconv.rb b/lib/drb/timeridconv.rb
deleted file mode 100644
index b460e2c987..0000000000
--- a/lib/drb/timeridconv.rb
+++ /dev/null
@@ -1,91 +0,0 @@
-require 'drb/drb'
-require 'monitor'
-
-module DRb
-  class TimerIdConv < DRbIdConv
-    class TimerHolder2
-      include MonitorMixin
-
-      class InvalidIndexError < RuntimeError; end
-
-      def initialize(timeout=600)
-        super()
-        @sentinel = Object.new
-        @gc = {}
-        @curr = {}
-        @renew = {}
-        @timeout = timeout
-        @keeper = keeper
-      end
-
-      def add(obj)
-        synchronize do
-          key = obj.__id__
-          @curr[key] = obj
-          return key
-        end
-      end
-
-      def fetch(key, dv=@sentinel)
-        synchronize do
-          obj = peek(key)
-          if obj == @sentinel
-            return dv unless dv == @sentinel
-            raise InvalidIndexError
-          end
-          @renew[key] = obj # KeepIt
-          return obj
-        end
-      end
-
-      def include?(key)
-        synchronize do
-          obj = peek(key)
-          return false if obj == @sentinel
-          true
-        end
-      end
-
-      def peek(key)
-        synchronize do
-          return @curr.fetch(key, @renew.fetch(key, @gc.fetch(key, @sentinel)))
-        end
-      end
-
-      private
-      def alternate
-        synchronize do
-          @gc = @curr       # GCed
-          @curr = @renew
-          @renew = {}
-        end
-      end
-
-      def keeper
-        Thread.new do
-          loop do
-            alternate
-            sleep(@timeout)
-          end
-        end
-      end
-    end
-
-    def initialize(timeout=600)
-      @holder = TimerHolder2.new(timeout)
-    end
-
-    def to_obj(ref)
-      return super if ref.nil?
-      @holder.fetch(ref)
-    rescue TimerHolder2::InvalidIndexError
-      raise "invalid reference"
-    end
-
-    def to_id(obj)
-      return @holder.add(obj)
-    end
-  end
-end
-
-# DRb.install_id_conv(TimerIdConv.new)
diff --git a/lib/drb/unix.rb b/lib/drb/unix.rb
deleted file mode 100644
index 6de5052451..0000000000
--- a/lib/drb/unix.rb
+++ /dev/null
@@ -1,108 +0,0 @@
-require 'socket'
-require 'drb/drb'
-require 'tmpdir'
-
-raise(LoadError, "UNIXServer is required") unless defined?(UNIXServer)
-
-module DRb
-
-  class DRbUNIXSocket < DRbTCPSocket
-    def self.parse_uri(uri)
-      if /^drbunix:(.*?)(\?(.*))?$/ =~ uri
-        filename = $1
-        option = $3
-        [filename, option]
-      else
-        raise(DRbBadScheme, uri) unless uri =~ /^drbunix:/
-        raise(DRbBadURI, 'can\'t parse uri:' + uri)
-      end
-    end
-
-    def self.open(uri, config)
-      filename, = parse_uri(uri)
-      filename.untaint
-      soc = UNIXSocket.open(filename)
-      self.new(uri, soc, config)
-    end
-
-    def self.open_server(uri, config)
-      filename, = parse_uri(uri)
-      if filename.size == 0
-        soc = temp_server
-        filename = soc.path
-        uri = 'drbunix:' + soc.path
-      else
-        soc = UNIXServer.open(filename)
-      end
-      owner = config[:UNIXFileOwner]
-      group = config[:UNIXFileGroup]
-      if owner || group
-        require 'etc'
-        owner = Etc.getpwnam( owner ).uid  if owner
-        group = Etc.getgrnam( group ).gid  if group
-        File.chown owner, group, filename
-      end
-      mode = config[:UNIXFileMode]
-      File.chmod(mode, filename) if mode
-
-      self.new(uri, soc, config, true)
-    end
-
-    def self.uri_option(uri, config)
-      filename, option = parse_uri(uri)
-      return "drbunix:#{filename}", option
-    end
-
-    def initialize(uri, soc, config={}, server_mode = false)
-      super(uri, soc, config)
-      set_sockopt(@socket)
-      @server_mode = server_mode
-      @acl = nil
-    end
-
-    # import from tempfile.rb
-    Max_try = 10
-    private
-    def self.temp_server
-      tmpdir = Dir::tmpdir
-      n = 0
-      while true
-        begin
-          tmpname = sprintf('%s/druby%d.%d', tmpdir, $$, n)
-          lock = tmpname + '.lock'
-          unless File.exist?(tmpname) or File.exist?(lock)
-            Dir.mkdir(lock)
-            break
-          end
-        rescue
-          raise "cannot generate tempfile `%s'" % tmpname if n >= Max_try
-          #sleep(1)
-        end
-        n += 1
-      end
-      soc = UNIXServer.new(tmpname)
-      Dir.rmdir(lock)
-      soc
-    end
-
-    public
-    def close
-      return unless @socket
-      path = @socket.path if @server_mode
-      @socket.close
-      File.unlink(path) if @server_mode
-      @socket = nil
-    end
-
-    def accept
-      s = @socket.accept
-      self.class.new(nil, s, @config)
-    end
-
-    def set_sockopt(soc)
-      soc.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC) if defined? Fcntl::FD_CLOEXEC
-    end
-  end
-
-  DRbProtocol.add_protocol(DRbUNIXSocket)
-end
diff --git a/lib/e2mmap.rb b/lib/e2mmap.rb
deleted file mode 100644
index 18a7ca003d..0000000000
--- a/lib/e2mmap.rb
+++ /dev/null
@@ -1,172 +0,0 @@
-#
-#   e2mmap.rb - for ruby 1.1
-#       $Release Version: 2.0$
-#       $Revision: 1.10 $
-#       by Keiju ISHITSUKA
-#
-# --
-#   Usage:
-#
-# U1)
-#   class Foo
-#     extend Exception2MessageMapper
-#     def_e2message ExistingExceptionClass, "message..."
-#     def_exception :NewExceptionClass, "message..."[, superclass]
-#     ...
-#   end
-#
-# U2)
-#   module Error
-#     extend Exception2MessageMapper
-#     def_e2meggage ExistingExceptionClass, "message..."
-#     def_exception :NewExceptionClass, "message..."[, superclass]
-#     ...
-#   end
-#   class Foo
-#     include Error
-#     ...
-#   end
-#
-#   foo = Foo.new
-#   foo.Fail ....
-#
-# U3)
-#   module Error
-#     extend Exception2MessageMapper
-#     def_e2message ExistingExceptionClass, "message..."
-#     def_exception :NewExceptionClass, "message..."[, superclass]
-#     ...
-#   end
-#   class Foo
-#     extend Exception2MessageMapper
-#     include Error
-#     ...
-#   end
-#
-#   Foo.Fail NewExceptionClass, arg...
-#   Foo.Fail ExistingExceptionClass, arg...
-#
-#
-module Exception2MessageMapper
-  @RCS_ID='-$Id: e2mmap.rb,v 1.10 1999/02/17 12:33:17 keiju Exp keiju $-'
-
-  E2MM = Exception2MessageMapper
-
-  def E2MM.extend_object(cl)
-    super
-    cl.bind(self) unless cl < E2MM
-  end
-
-  def bind(cl)
-    self.module_eval %[
-      def Raise(err = nil, *rest)
-        Exception2MessageMapper.Raise(self.class, err, *rest)
-      end
-      alias Fail Raise
-
-      def self.included(mod)
-        mod.extend Exception2MessageMapper
-      end
-    ]
-  end
-
-  # Fail(err, *rest)
-  #     err:    exception
-  #     rest:   message arguments
-  #
-  def Raise(err = nil, *rest)
-    E2MM.Raise(self, err, *rest)
-  end
-  alias Fail Raise
-  alias fail Raise
-
-  # def_e2message(c, m)
-  #         c:  exception
-  #         m:  message_form
-  #     define exception c with message m.
-  #
-  def def_e2message(c, m)
-    E2MM.def_e2message(self, c, m)
-  end
-
-  # def_exception(n, m, s)
-  #         n:  exception_name
-  #         m:  message_form
-  #         s:  superclass(default: StandardError)
-  #     define exception named ``c'' with message m.
-  #
-  def def_exception(n, m, s = StandardError)
-    E2MM.def_exception(self, n, m, s)
-  end
-
-  #
-  # Private definitions.
-  #
-  # {[class, exp] => message, ...}
-  @MessageMap = {}
-
-  # E2MM.def_e2message(k, e, m)
-  #         k:  class to define exception under.
-  #         e:  exception
-  #         m:  message_form
-  #     define exception c with message m.
-  #
-  def E2MM.def_e2message(k, c, m)
-    E2MM.instance_eval{@MessageMap[[k, c]] = m}
-    c
-  end
-
-  # E2MM.def_exception(k, n, m, s)
-  #         k:  class to define exception under.
-  #         n:  exception_name
-  #         m:  message_form
-  #         s:  superclass(default: StandardError)
-  #     define exception named ``c'' with message m.
-  #
-  def E2MM.def_exception(k, n, m, s = StandardError)
-    n = n.id2name if n.kind_of?(Fixnum)
-    e = Class.new(s)
-    E2MM.instance_eval{@MessageMap[[k, e]] = m}
-    k.const_set(n, e)
-  end
-
-  # Fail(klass, err, *rest)
-  #     klass:  class to define exception under.
-  #     err:    exception
-  #     rest:   message arguments
-  #
-  def E2MM.Raise(klass = E2MM, err = nil, *rest)
-    if form = e2mm_message(klass, err)
-      b = $@.nil? ? caller(1) : $@
-      #p $@
-      #p __FILE__
-      b.shift if b[0] =~ /^#{Regexp.quote(__FILE__)}:/
-      raise err, sprintf(form, *rest), b
-    else
-      E2MM.Fail E2MM, ErrNotRegisteredException, err.inspect
-    end
-  end
-  class << E2MM
-    alias Fail Raise
-  end
-
-  def E2MM.e2mm_message(klass, exp)
-    for c in klass.ancestors
-      if mes = @MessageMap[[c,exp]]
-        #p mes
-        m = klass.instance_eval('"' + mes + '"')
-        return m
-      end
-    end
-    nil
-  end
-  class << self
-    alias message e2mm_message
-  end
-
-  E2MM.def_exception(E2MM,
-                     :ErrNotRegisteredException,
-                     "not registerd exception(%s)")
-end
-
-
diff --git a/lib/erb.rb b/lib/erb.rb
index bb47943a86..bde90de841 100644
--- a/lib/erb.rb
+++ b/lib/erb.rb
@@ -1,3 +1,5 @@
+# -*- coding: us-ascii -*-
+# frozen_string_literal: true
 # = ERB -- Ruby Templating
 #
 # Author:: Masatoshi SEKI
@@ -10,979 +12,1168 @@
 #
 # You can redistribute it and/or modify it under the same terms as Ruby.
 
+# A NOTE ABOUT TERMS:
 #
-# = ERB -- Ruby Templating
+# Formerly: The documentation in this file used the term _template_ to refer to an ERB object.
 #
-# == Introduction
+# Now: The documentation in this file uses the term _template_
+# to refer to the string input to ERB.new.
 #
-# ERB provides an easy to use but powerful templating system for Ruby.  Using
-# ERB, actual Ruby code can be added to any plain text document for the
-# purposes of generating document information details and/or flow control.
+# The reason for the change:  When documenting the ERB executable erb,
+# we need a term that refers to its string input;
+# _source_ is not a good idea, because ERB#src means something entirely different;
+# the two different sorts of sources would bring confusion.
 #
-# A very simple example is this:
+# Therefore we use the term _template_ to refer to:
 #
-#   require 'erb'
+# - The string input to ERB.new
+# - The string input to executable erb.
 #
-#   x = 42
-#   template = ERB.new <<-EOF
-#     The value of x is: <%= x %>
-#   EOF
-#   puts template.result(binding)
+
+require 'erb/version'
+require 'erb/compiler'
+require 'erb/def_method'
+require 'erb/util'
+
+# :markup: markdown
 #
-# <em>Prints:</em> The value of x is: 42
+# Class **ERB** (the name stands for **Embedded Ruby**)
+# is an easy-to-use, but also very powerful, [template processor][template processor].
 #
-# More complex examples are given below.
+# ## Usage
 #
+# Before you can use \ERB, you must first require it
+# (examples on this page assume that this has been done):
 #
-# == Recognized Tags
+# ```
+# require 'erb'
+# ```
 #
-# ERB recognizes certain tags in the provided template and converts them based
-# on the rules below:
+# ## In Brief
 #
-#   <% Ruby code -- inline with output %>
-#   <%= Ruby expression -- replace with result %>
-#   <%# comment -- ignored -- useful in testing %>
-#   % a line of Ruby code -- treated as <% line %> (optional -- see ERB.new)
-#   %% replaced with % if first thing on a line and % processing is used
-#   <%% or %%> -- replace with <% or %> respectively
+# Here's how \ERB works:
 #
-# All other text is passed through ERB filtering unchanged.
+# - You can create a *template*: a plain-text string that includes specially formatted *tags*..
+# - You can create an \ERB object to store the template.
+# - You can call instance method ERB#result to get the *result*.
 #
+# \ERB supports tags of three kinds:
 #
-# == Options
+# - [Expression tags][expression tags]:
+#   each begins with `'<%='`, ends with `'%>'`; contains a Ruby expression;
+#   in the result, the value of the expression replaces the entire tag:
 #
-# There are several settings you can change when you use ERB:
-# * the nature of the tags that are recognized;
-# * the value of <tt>$SAFE</tt> under which the template is run;
-# * the binding used to resolve local variables in the template.
+#         template = 'The magic word is <%= magic_word %>.'
+#         erb = ERB.new(template)
+#         magic_word = 'xyzzy'
+#         erb.result(binding) # => "The magic word is xyzzy."
 #
-# See the ERB.new and ERB#result methods for more detail.
+#     The above call to #result passes argument `binding`,
+#     which contains the binding of variable `magic_word` to its string value `'xyzzy'`.
 #
-# == Character encodings
+#     The below call to #result need not pass a binding,
+#     because its expression `Date::DAYNAMES` is globally defined.
 #
-# ERB (or ruby code generated by ERB) returns a string in the same
-# character encoding as the input string.  When the input string has
-# a magic comment, however, it returns a string in the encoding specified
-# by the magic comment.
+#         ERB.new('Today is <%= Date::DAYNAMES[Date.today.wday] %>.').result # => "Today is Monday."
 #
-#   # -*- coding: UTF-8 -*-
-#   require 'erb'
+# - [Execution tags][execution tags]:
+#   each begins with `'<%'`, ends with `'%>'`; contains Ruby code to be executed:
 #
-#   template = ERB.new <<EOF
-#   <%#-*- coding: Big5 -*-%>
-#     \_\_ENCODING\_\_ is <%= \_\_ENCODING\_\_ %>.
-#   EOF
-#   puts template.result
+#          template = '<% File.write("t.txt", "Some stuff.") %>'
+#          ERB.new(template).result
+#          File.read('t.txt') # => "Some stuff."
 #
-# <em>Prints:</em> \_\_ENCODING\_\_ is Big5.
+# - [Comment tags][comment tags]:
+#   each begins with `'<%#'`, ends with `'%>'`; contains comment text;
+#   in the result, the entire tag is omitted.
 #
+#          template = 'Some stuff;<%# Note to self: figure out what the stuff is. %> more stuff.'
+#          ERB.new(template).result # => "Some stuff; more stuff."
 #
-# == Examples
+# ## Some Simple Examples
 #
-# === Plain Text
+# Here's a simple example of \ERB in action:
 #
-# ERB is useful for any generic templating situation.  Note that in this example, we use the
-# convenient "% at start of line" tag, and we quote the template literally with
-# <tt>%q{...}</tt> to avoid trouble with the backslash.
+# ```
+# template = 'The time is <%= Time.now %>.'
+# erb = ERB.new(template)
+# erb.result
+# # => "The time is 2025-09-09 10:49:26 -0500."
+# ```
 #
-#   require "erb"
+# Details:
 #
-#   # Create template.
-#   template = %q{
-#     From:  James Edward Gray II <james@grayproductions.net>
-#     To:  <%= to %>
-#     Subject:  Addressing Needs
+# 1. A plain-text string is assigned to variable `template`.
+#    Its embedded [expression tag][expression tags] `'<%= Time.now %>'` includes a Ruby expression, `Time.now`.
+# 2. The string is put into a new \ERB object, and stored in variable `erb`.
+# 4. Method call `erb.result` generates a string that contains the run-time value of `Time.now`,
+#    as computed at the time of the call.
 #
-#     <%= to[/\w+/] %>:
+# The
+# \ERB object may be re-used:
 #
-#     Just wanted to send a quick note assuring that your needs are being
-#     addressed.
+# ```
+# erb.result
+# # => "The time is 2025-09-09 10:49:33 -0500."
+# ```
 #
-#     I want you to know that my team will keep working on the issues,
-#     especially:
+# Another example:
 #
-#     <%# ignore numerous minor requests -- focus on priorities %>
-#     % priorities.each do |priority|
-#       * <%= priority %>
-#     % end
+# ```
+# template = 'The magic word is <%= magic_word %>.'
+# erb = ERB.new(template)
+# magic_word = 'abracadabra'
+# erb.result(binding)
+# # => "The magic word is abracadabra."
+# ```
 #
-#     Thanks for your patience.
+# Details:
 #
-#     James Edward Gray II
-#   }.gsub(/^  /, '')
+# 1. As before, a plain-text string is assigned to variable `template`.
+#    Its embedded [expression tag][expression tags] `'<%= magic_word %>'` has a variable *name*, `magic_word`.
+# 2. The string is put into a new \ERB object, and stored in variable `erb`;
+#    note that `magic_word` need not be defined before the \ERB object is created.
+# 3. `magic_word = 'abracadabra'` assigns a value to variable `magic_word`.
+# 4. Method call `erb.result(binding)` generates a string
+#    that contains the *value* of `magic_word`.
 #
-#   message = ERB.new(template, 0, "%<>")
+# As before, the \ERB object may be re-used:
 #
-#   # Set up template data.
-#   to = "Community Spokesman <spokesman@ruby_community.org>"
-#   priorities = [ "Run Ruby Quiz",
-#                  "Document Modules",
-#                  "Answer Questions on Ruby Talk" ]
+# ```
+# magic_word = 'xyzzy'
+# erb.result(binding)
+# # => "The magic word is xyzzy."
+# ```
 #
-#   # Produce result.
-#   email = message.result
-#   puts email
+# ## Bindings
 #
-# <i>Generates:</i>
+# A call to method #result, which produces the formatted result string,
+# requires a [Binding object][binding object] as its argument.
+#
+# The binding object provides the bindings for expressions in [expression tags][expression tags].
+#
+# There are three ways to provide the required binding:
+#
+# - [Default binding][default binding].
+# - [Local binding][local binding].
+# - [Augmented binding][augmented binding]
+#
+# ### Default Binding
+#
+# When you pass no `binding` argument to method #result,
+# the method uses its default binding: the one returned by method #new_toplevel.
+# This binding has the bindings defined by Ruby itself,
+# which are those for Ruby's constants and variables.
+#
+# That binding is sufficient for an expression tag that refers only to Ruby's constants and variables;
+# these expression tags refer only to Ruby's global constant `RUBY_COPYRIGHT` and global variable `$0`:
 #
-#   From:  James Edward Gray II <james@grayproductions.net>
-#   To:  Community Spokesman <spokesman@ruby_community.org>
-#   Subject:  Addressing Needs
+# ```
+# template = <<TEMPLATE
+# The Ruby copyright is <%= RUBY_COPYRIGHT.inspect %>.
+# The current process is <%= $0 %>.
+# TEMPLATE
+# puts ERB.new(template).result
+# The Ruby copyright is "ruby - Copyright (C) 1993-2025 Yukihiro Matsumoto".
+# The current process is irb.
+# ```
+#
+# (The current process is `irb` because that's where we're doing these examples!)
+#
+# ### Local Binding
+#
+# The default binding is *not* sufficient for an expression
+# that refers to a a constant or variable that is not defined there:
+#
+# ```
+# Foo = 1 # Defines local constant Foo.
+# foo = 2 # Defines local variable foo.
+# template = <<TEMPLATE
+# The current value of constant Foo is <%= Foo %>.
+# The current value of variable foo is <%= foo %>.
+# The Ruby copyright is <%= RUBY_COPYRIGHT.inspect %>.
+# The current process is <%= $0 %>.
+# TEMPLATE
+# erb = ERB.new(template)
+# ```
+#
+# This call below raises `NameError` because although `Foo` and `foo` are defined locally,
+# they are not defined in the default binding:
+#
+# ```
+# erb.result # Raises NameError.
+# ```
+#
+# To make the locally-defined constants and variables available,
+# you can call #result with the local binding:
+#
+# ```
+# puts erb.result(binding)
+# The current value of constant Foo is 1.
+# The current value of variable foo is 2.
+# The Ruby copyright is "ruby - Copyright (C) 1993-2025 Yukihiro Matsumoto".
+# The current process is irb.
+# ```
+#
+# ### Augmented Binding
+#
+# Another way to make variable bindings (but not constant bindings) available
+# is to use method #result_with_hash(hash);
+# the passed hash has name/value pairs that are to be used to define and assign variables
+# in a copy of the default binding:
+#
+# ```
+# template = <<TEMPLATE
+# The current value of variable bar is <%= bar %>.
+# The current value of variable baz is <%= baz %>.
+# The Ruby copyright is <%= RUBY_COPYRIGHT.inspect %>.
+# The current process is <%= $0 %>.
+# TEMPLATE
+# erb = ERB.new(template)
+# ```
+#
+# Both of these calls raise `NameError`, because `bar` and `baz`
+# are not defined in either the default binding or the local binding.
+#
+# ```
+# puts erb.result          # Raises NameError.
+# puts erb.result(binding) # Raises NameError.
+# ```
+#
+# This call passes a hash that causes `bar` and `baz` to be defined
+# in a new binding (derived from #new_toplevel):
+#
+# ```
+# hash = {bar: 3, baz: 4}
+# puts erb.result_with_hash(hash)
+# The current value of variable bar is 3.
+# The current value of variable baz is 4.
+# The Ruby copyright is "ruby - Copyright (C) 1993-2025 Yukihiro Matsumoto".
+# The current process is irb.
+# ```
+#
+# ## Tags
+#
+# The examples above use expression tags.
+# These are the tags available in \ERB:
+#
+# - [Expression tag][expression tags]: the tag contains a Ruby expression;
+#   in the result, the entire tag is to be replaced with the run-time value of the expression.
+# - [Execution tag][execution tags]: the tag contains Ruby code;
+#   in the result, the entire tag is to be replaced with the run-time value of the code.
+# - [Comment tag][comment tags]: the tag contains comment code;
+#   in the result, the entire tag is to be omitted.
+#
+# ### Expression Tags
+#
+# You can embed a Ruby expression in a template using an *expression tag*.
+#
+# Its syntax is `<%= _expression_ %>`,
+# where *expression* is any valid Ruby expression.
+#
+# When you call method #result,
+# the method evaluates the expression and replaces the entire expression tag with the expression's value:
+#
+# ```
+# ERB.new('Today is <%= Date::DAYNAMES[Date.today.wday] %>.').result
+# # => "Today is Monday."
+# ERB.new('Tomorrow will be <%= Date::DAYNAMES[Date.today.wday + 1] %>.').result
+# # => "Tomorrow will be Tuesday."
+# ERB.new('Yesterday was <%= Date::DAYNAMES[Date.today.wday - 1] %>.').result
+# # => "Yesterday was Sunday."
+# ```
+#
+# Note that whitespace before and after the expression
+# is allowed but not required,
+# and that such whitespace is stripped from the result.
+#
+# ```
+# ERB.new('My appointment is on <%=Date::DAYNAMES[Date.today.wday + 2]%>.').result
+# # => "My appointment is on Wednesday."
+# ERB.new('My appointment is on <%=     Date::DAYNAMES[Date.today.wday + 2]    %>.').result
+# # => "My appointment is on Wednesday."
+# ```
+#
+# ### Execution Tags
+#
+# You can embed Ruby executable code in template using an *execution tag*.
+#
+# Its syntax is `<% _code_ %>`,
+# where *code* is any valid Ruby code.
+#
+# When you call method #result,
+# the method executes the code and removes the entire execution tag
+# (generating no text in the result):
+#
+# ```
+# ERB.new('foo <% Dir.chdir("C:/") %> bar').result # => "foo  bar"
+# ```
+#
+# Whitespace before and after the embedded code is optional:
+#
+# ```
+# ERB.new('foo <%Dir.chdir("C:/")%> bar').result   # => "foo  bar"
+# ```
+#
+# You can interleave text with execution tags to form a control structure
+# such as a conditional, a loop, or a `case` statements.
+#
+# Conditional:
+#
+# ```
+# template = <<TEMPLATE
+# <% if verbosity %>
+# An error has occurred.
+# <% else %>
+# Oops!
+# <% end %>
+# TEMPLATE
+# erb = ERB.new(template)
+# verbosity = true
+# erb.result(binding)
+# # => "\nAn error has occurred.\n\n"
+# verbosity = false
+# erb.result(binding)
+# # => "\nOops!\n\n"
+# ```
+#
+# Note that the interleaved text may itself contain expression tags:
+#
+# Loop:
+#
+# ```
+# template = <<TEMPLATE
+# <% Date::ABBR_DAYNAMES.each do |dayname| %>
+# <%= dayname %>
+# <% end %>
+# TEMPLATE
+# ERB.new(template).result
+# # => "\nSun\n\nMon\n\nTue\n\nWed\n\nThu\n\nFri\n\nSat\n\n"
+# ```
+#
+# Other, non-control, lines of Ruby code may be interleaved with the text,
+# and the Ruby code may itself contain regular Ruby comments:
+#
+# ```
+# template = <<TEMPLATE
+# <% 3.times do %>
+# <%= Time.now %>
+# <% sleep(1) # Let's make the times different. %>
+# <% end %>
+# TEMPLATE
+# ERB.new(template).result
+# # => "\n2025-09-09 11:36:02 -0500\n\n\n2025-09-09 11:36:03 -0500\n\n\n2025-09-09 11:36:04 -0500\n\n\n"
+# ```
+#
+# The execution tag may also contain multiple lines of code:
+#
+# ```
+# template = <<TEMPLATE
+# <%
+#   (0..2).each do |i|
+#     (0..2).each do |j|
+# %>
+# * <%=i%>,<%=j%>
+# <%
+#     end
+#   end
+# %>
+# TEMPLATE
+# ERB.new(template).result
+# # => "\n* 0,0\n\n* 0,1\n\n* 0,2\n\n* 1,0\n\n* 1,1\n\n* 1,2\n\n* 2,0\n\n* 2,1\n\n* 2,2\n\n"
+# ```
+#
+# #### Shorthand Format for Execution Tags
+#
+# You can use keyword argument `trim_mode: '%'` to enable a shorthand format for execution tags;
+# this example uses the shorthand format `% _code_` instead of `<% _code_ %>`:
+#
+# ```
+# template = <<TEMPLATE
+# % priorities.each do |priority|
+#   * <%= priority %>
+# % end
+# TEMPLATE
+# erb = ERB.new(template, trim_mode: '%')
+# priorities = [ 'Run Ruby Quiz',
+#                'Document Modules',
+#                'Answer Questions on Ruby Talk' ]
+# puts erb.result(binding)
+#   * Run Ruby Quiz
+#   * Document Modules
+#   * Answer Questions on Ruby Talk
+# ```
+#
+# Note that in the shorthand format, the character `'%'` must be the first character in the code line
+# (no leading whitespace).
+#
+# #### Suppressing Unwanted Blank Lines
+#
+# With keyword argument `trim_mode` not given,
+# all blank lines go into the result:
+#
+# ```
+# template = <<TEMPLATE
+# <% if true %>
+# <%= RUBY_VERSION %>
+# <% end %>
+# TEMPLATE
+# ERB.new(template).result.lines.each {|line| puts line.inspect }
+# "\n"
+# "3.4.5\n"
+# "\n"
+# ```
+#
+# You can give `trim_mode: '-'`, you can suppress each blank line
+# whose source line ends with `-%>` (instead of `%>`):
+#
+# ```
+# template = <<TEMPLATE
+# <% if true -%>
+# <%= RUBY_VERSION %>
+# <% end -%>
+# TEMPLATE
+# ERB.new(template, trim_mode: '-').result.lines.each {|line| puts line.inspect }
+# "3.4.5\n"
+# ```
+#
+# It is an error to use the trailing `'-%>'` notation without `trim_mode: '-'`:
+#
+# ```
+# ERB.new(template).result.lines.each {|line| puts line.inspect } # Raises SyntaxError.
+# ```
+#
+# #### Suppressing Unwanted Newlines
+#
+# Consider this template:
+#
+# ```
+# template = <<TEMPLATE
+# <% RUBY_VERSION %>
+# <%= RUBY_VERSION %>
+# foo <% RUBY_VERSION %>
+# foo <%= RUBY_VERSION %>
+# TEMPLATE
+# ```
+#
+# With keyword argument `trim_mode` not given, all newlines go into the result:
+#
+# ```
+# ERB.new(template).result.lines.each {|line| puts line.inspect }
+# "\n"
+# "3.4.5\n"
+# "foo \n"
+# "foo 3.4.5\n"
+# ```
+#
+# You can give `trim_mode: '>'` to suppress the trailing newline
+# for each line that ends with `'%>'` (regardless of its beginning):
+#
+# ```
+# ERB.new(template, trim_mode: '>').result.lines.each {|line| puts line.inspect }
+# "3.4.5foo foo 3.4.5"
+# ```
+#
+# You can give `trim_mode: '<>'` to suppress the trailing newline
+# for each line that both begins with `'<%'` and ends with `'%>'`:
+#
+# ```
+# ERB.new(template, trim_mode: '<>').result.lines.each {|line| puts line.inspect }
+# "3.4.5foo \n"
+# "foo 3.4.5\n"
+# ```
+#
+# #### Combining Trim Modes
+#
+# You can combine certain trim modes:
+#
+# - `'%-'`: Enable shorthand and omit each blank line ending with `'-%>'`.
+# - `'%>'`: Enable shorthand and omit newline for each line ending with `'%>'`.
+# - `'%<>'`: Enable shorthand and omit newline for each line starting with `'<%'` and ending with `'%>'`.
+#
+# ### Comment Tags
+#
+# You can embed a comment in a template using a *comment tag*;
+# its syntax is `<%# _text_ %>`,
+# where *text* is the text of the comment.
+#
+# When you call method #result,
+# it removes the entire comment tag
+# (generating no text in the result).
+#
+# Example:
+#
+# ```
+# template = 'Some stuff;<%# Note to self: figure out what the stuff is. %> more stuff.'
+# ERB.new(template).result # => "Some stuff; more stuff."
+# ```
+#
+# A comment tag may appear anywhere in the template.
+#
+# Note that the beginning of the tag must be `'<%#'`, not `'<% #'`.
+#
+# In this example, the tag begins with `'<% #'`, and so is an execution tag, not a comment tag;
+# the cited code consists entirely of a Ruby-style comment (which is of course ignored):
+#
+# ```
+# ERB.new('Some stuff;<% # Note to self: figure out what the stuff is. %> more stuff.').result
+# # => "Some stuff;"
+# ```
+#
+# ## Encodings
+#
+# An \ERB object has an [encoding][encoding],
+# which is by default the encoding of the template string;
+# the result string will also have that encoding.
 #
-#   Community:
+# ```
+# template = <<TEMPLATE
+# <%# Comment. %>
+# TEMPLATE
+# erb = ERB.new(template)
+# template.encoding   # => #<Encoding:UTF-8>
+# erb.encoding        # => #<Encoding:UTF-8>
+# erb.result.encoding # => #<Encoding:UTF-8>
+# ```
 #
-#   Just wanted to send a quick note assuring that your needs are being addressed.
+# You can specify a different encoding by adding a [magic comment][magic comments]
+# at the top of the given template:
 #
-#   I want you to know that my team will keep working on the issues, especially:
+# ```
+# template = <<TEMPLATE
+# <%#-*- coding: Big5 -*-%>
+# <%# Comment. %>
+# TEMPLATE
+# erb = ERB.new(template)
+# template.encoding   # => #<Encoding:UTF-8>
+# erb.encoding        # => #<Encoding:Big5>
+# erb.result.encoding # => #<Encoding:Big5>
+# ```
 #
-#       * Run Ruby Quiz
-#       * Document Modules
-#       * Answer Questions on Ruby Talk
+# ## Error Reporting
 #
-#   Thanks for your patience.
+# Consider this template (containing an error):
 #
-#   James Edward Gray II
+# ```
+# template = '<%= nosuch %>'
+# erb = ERB.new(template)
+# ```
 #
-# === Ruby in HTML
+# When \ERB reports an error,
+# it includes a file name (if available) and a line number;
+# the file name comes from method #filename, the line number from method #lineno.
 #
-# ERB is often used in <tt>.rhtml</tt> files (HTML with embedded Ruby).  Notice the need in
-# this example to provide a special binding when the template is run, so that the instance
-# variables in the Product object can be resolved.
+# Initially, those values are `nil` and `0`, respectively;
+# these initial values are reported as `'(erb)'` and `1`, respectively:
 #
-#   require "erb"
+# ```
+# erb.filename # => nil
+# erb.lineno   # => 0
+# erb.result
+# (erb):1:in '<main>': undefined local variable or method 'nosuch' for main (NameError)
+# ```
 #
-#   # Build template data class.
-#   class Product
-#     def initialize( code, name, desc, cost )
-#       @code = code
-#       @name = name
-#       @desc = desc
-#       @cost = cost
+# You can use methods #filename= and #lineno= to assign values
+# that are more meaningful in your context:
 #
-#       @features = [ ]
-#     end
+# ```
+# erb.filename = 't.txt'
+# erb.lineno = 555
+# erb.result
+# t.txt:556:in '<main>': undefined local variable or method 'nosuch' for main (NameError)
+# ```
 #
-#     def add_feature( feature )
-#       @features << feature
-#     end
+# You can use method #location= to set both values:
 #
-#     # Support templating of member data.
-#     def get_binding
-#       binding
-#     end
+# ```
+# erb.location = ['u.txt', 999]
+# erb.result
+# u.txt:1000:in '<main>': undefined local variable or method 'nosuch' for main (NameError)
+# ```
+#
+# ## Plain Text with Embedded Ruby
+#
+# Here's a plain-text template;
+# it uses the literal notation `'%q{ ... }'` to define the template
+# (see [%q literals][%q literals]);
+# this avoids problems with backslashes.
+#
+# ```
+# template = %q{
+# From:  James Edward Gray II <james@grayproductions.net>
+# To:  <%= to %>
+# Subject:  Addressing Needs
+#
+# <%= to[/\w+/] %>:
+#
+# Just wanted to send a quick note assuring that your needs are being
+# addressed.
+#
+# I want you to know that my team will keep working on the issues,
+# especially:
+#
+# <%# ignore numerous minor requests -- focus on priorities %>
+# % priorities.each do |priority|
+#   * <%= priority %>
+# % end
+#
+# Thanks for your patience.
+#
+# James Edward Gray II
+# }
+# ```
+#
+# The template will need these:
+#
+# ```
+# to = 'Community Spokesman <spokesman@ruby_community.org>'
+# priorities = [ 'Run Ruby Quiz',
+#                'Document Modules',
+#                'Answer Questions on Ruby Talk' ]
+# ```
+#
+# Finally, create the \ERB object and get the result
+#
+# ```
+# erb = ERB.new(template, trim_mode: '%<>')
+# puts erb.result(binding)
+#
+# From:  James Edward Gray II <james@grayproductions.net>
+# To:  Community Spokesman <spokesman@ruby_community.org>
+# Subject:  Addressing Needs
+#
+# Community:
+#
+# Just wanted to send a quick note assuring that your needs are being
+# addressed.
+#
+# I want you to know that my team will keep working on the issues,
+# especially:
+#
+# * Run Ruby Quiz
+# * Document Modules
+# * Answer Questions on Ruby Talk
 #
-#     # ...
+# Thanks for your patience.
+#
+# James Edward Gray II
+# ```
+#
+# ## HTML with Embedded Ruby
+#
+# This example shows an HTML template.
+#
+# First, here's a custom class, `Product`:
+#
+# ```
+# class Product
+#   def initialize(code, name, desc, cost)
+#     @code = code
+#     @name = name
+#     @desc = desc
+#     @cost = cost
+#     @features = []
 #   end
 #
-#   # Create template.
-#   template = %{
-#     <html>
-#       <head><title>Ruby Toys -- <%= @name %></title></head>
-#       <body>
-#
-#         <h1><%= @name %> (<%= @code %>)</h1>
-#         <p><%= @desc %></p>
-#
-#         <ul>
-#           <% @features.each do |f| %>
-#             <li><b><%= f %></b></li>
-#           <% end %>
-#         </ul>
-#
-#         <p>
-#           <% if @cost < 10 %>
-#             <b>Only <%= @cost %>!!!</b>
-#           <% else %>
-#              Call for a price, today!
-#           <% end %>
-#         </p>
-#
-#       </body>
-#     </html>
-#   }.gsub(/^  /, '')
-#
-#   rhtml = ERB.new(template)
-#
-#   # Set up template data.
-#   toy = Product.new( "TZ-1002",
-#                      "Rubysapien",
-#                      "Geek's Best Friend!  Responds to Ruby commands...",
-#                      999.95 )
-#   toy.add_feature("Listens for verbal commands in the Ruby language!")
-#   toy.add_feature("Ignores Perl, Java, and all C variants.")
-#   toy.add_feature("Karate-Chop Action!!!")
-#   toy.add_feature("Matz signature on left leg.")
-#   toy.add_feature("Gem studded eyes... Rubies, of course!")
-#
-#   # Produce result.
-#   rhtml.run(toy.get_binding)
-#
-# <i>Generates (some blank lines removed):</i>
-#
-#    <html>
-#      <head><title>Ruby Toys -- Rubysapien</title></head>
-#      <body>
-#
-#        <h1>Rubysapien (TZ-1002)</h1>
-#        <p>Geek's Best Friend!  Responds to Ruby commands...</p>
-#
-#        <ul>
-#            <li><b>Listens for verbal commands in the Ruby language!</b></li>
-#            <li><b>Ignores Perl, Java, and all C variants.</b></li>
-#            <li><b>Karate-Chop Action!!!</b></li>
-#            <li><b>Matz signature on left leg.</b></li>
-#            <li><b>Gem studded eyes... Rubies, of course!</b></li>
-#        </ul>
-#
-#        <p>
-#             Call for a price, today!
-#        </p>
-#
-#      </body>
-#    </html>
-#
-#
-# == Notes
-#
-# There are a variety of templating solutions available in various Ruby projects:
-# * ERB's big brother, eRuby, works the same but is written in C for speed;
-# * Amrita (smart at producing HTML/XML);
-# * cs/Template (written in C for speed);
-# * RDoc, distributed with Ruby, uses its own template engine, which can be reused elsewhere;
-# * and others; search the RAA.
-#
-# Rails, the web application framework, uses ERB to create views.
+#   def add_feature(feature)
+#     @features << feature
+#   end
+#
+#   # Support templating of member data.
+#   def get_binding
+#     binding
+#   end
+#
+# end
+# ```
+#
+# The template below will need these values:
+#
+# ```
+# toy = Product.new('TZ-1002',
+#                   'Rubysapien',
+#                   "Geek's Best Friend!  Responds to Ruby commands...",
+#                   999.95
+#                   )
+# toy.add_feature('Listens for verbal commands in the Ruby language!')
+# toy.add_feature('Ignores Perl, Java, and all C variants.')
+# toy.add_feature('Karate-Chop Action!!!')
+# toy.add_feature('Matz signature on left leg.')
+# toy.add_feature('Gem studded eyes... Rubies, of course!')
+# ```
+#
+# Here's the HTML:
+#
+# ```
+# template = <<TEMPLATE
+# <html>
+#   <head><title>Ruby Toys -- <%= @name %></title></head>
+#   <body>
+#     <h1><%= @name %> (<%= @code %>)</h1>
+#     <p><%= @desc %></p>
+#     <ul>
+#       <% @features.each do |f| %>
+#         <li><b><%= f %></b></li>
+#       <% end %>
+#     </ul>
+#     <p>
+#       <% if @cost < 10 %>
+#         <b>Only <%= @cost %>!!!</b>
+#       <% else %>
+#          Call for a price, today!
+#       <% end %>
+#     </p>
+#   </body>
+# </html>
+# TEMPLATE
+# ```
+#
+# Finally, create the \ERB object and get the result (omitting some blank lines):
+#
+# ```
+# erb = ERB.new(template)
+# puts erb.result(toy.get_binding)
+# <html>
+#   <head><title>Ruby Toys -- Rubysapien</title></head>
+#   <body>
+#     <h1>Rubysapien (TZ-1002)</h1>
+#     <p>Geek's Best Friend!  Responds to Ruby commands...</p>
+#     <ul>
+#         <li><b>Listens for verbal commands in the Ruby language!</b></li>
+#         <li><b>Ignores Perl, Java, and all C variants.</b></li>
+#         <li><b>Karate-Chop Action!!!</b></li>
+#         <li><b>Matz signature on left leg.</b></li>
+#         <li><b>Gem studded eyes... Rubies, of course!</b></li>
+#     </ul>
+#     <p>
+#          Call for a price, today!
+#     </p>
+#   </body>
+# </html>
+# ```
+#
+#
+# ## Other Template Processors
+#
+# Various Ruby projects have their own template processors.
+# The Ruby Processing System [RDoc][rdoc], for example, has one that can be used elsewhere.
+#
+# Other popular template processors may found in the [Template Engines][template engines] page
+# of the Ruby Toolbox.
+#
+# [%q literals]: https://docs.ruby-lang.org/en/master/syntax/literals_rdoc.html#label-25q-3A+Non-Interpolable+String+Literals
+# [augmented binding]: rdoc-ref:ERB@Augmented+Binding
+# [binding object]: https://docs.ruby-lang.org/en/master/Binding.html
+# [comment tags]: rdoc-ref:ERB@Comment+Tags
+# [default binding]: rdoc-ref:ERB@Default+Binding
+# [encoding]: https://docs.ruby-lang.org/en/master/Encoding.html
+# [execution tags]: rdoc-ref:ERB@Execution+Tags
+# [expression tags]: rdoc-ref:ERB@Expression+Tags
+# [kernel#binding]: https://docs.ruby-lang.org/en/master/Kernel.html#method-i-binding
+# [local binding]: rdoc-ref:ERB@Local+Binding
+# [magic comments]: https://docs.ruby-lang.org/en/master/syntax/comments_rdoc.html#label-Magic+Comments
+# [rdoc]: https://ruby.github.io/rdoc
+# [sprintf]: https://docs.ruby-lang.org/en/master/Kernel.html#method-i-sprintf
+# [template engines]: https://www.ruby-toolbox.com/categories/template_engines
+# [template processor]: https://en.wikipedia.org/wiki/Template_processor
 #
 class ERB
-  Revision = '$Date::                           $'      #'
-
-  # Returns revision information for the erb.rb module.
+  # :markup: markdown
+  #
+  # :call-seq:
+  #   self.version -> string
+  #
+  # Returns the string \ERB version.
   def self.version
-    "erb.rb [2.1.0 #{ERB::Revision.split[1]}]"
+    VERSION
   end
-end
 
-#--
-# ERB::Compiler
-class ERB
-  # = ERB::Compiler
+  # :markup: markdown
   #
-  # Compiles ERB templates into Ruby code; the compiled code produces the
-  # template result when evaluated. ERB::Compiler provides hooks to define how
-  # generated output is handled.
+  # :call-seq:
+  #   ERB.new(template, trim_mode: nil, eoutvar: '_erbout')
   #
-  # Internally ERB does something like this to generate the code returned by
-  # ERB#src:
+  # Returns a new \ERB object containing the given string +template+.
   #
-  #   compiler = ERB::Compiler.new('<>')
-  #   compiler.pre_cmd    = ["_erbout=''"]
-  #   compiler.put_cmd    = "_erbout.concat"
-  #   compiler.insert_cmd = "_erbout.concat"
-  #   compiler.post_cmd   = ["_erbout"]
+  # For details about `template`, its embedded tags, and generated results, see ERB.
   #
-  #   code, enc = compiler.compile("Got <%= obj %>!\n")
-  #   puts code
+  # **Keyword Argument `trim_mode`**
   #
-  # <i>Generates</i>:
+  # You can use keyword argument `trim_mode: '%'`
+  # to enable the [shorthand format][shorthand format] for execution tags.
   #
-  #   #coding:UTF-8
-  #   _erbout=''; _erbout.concat "Got "; _erbout.concat(( obj ).to_s); _erbout.concat "!\n"; _erbout
+  # This value allows [blank line control][blank line control]:
   #
-  # By default the output is sent to the print method.  For example:
+  # - `'-'`: Omit each blank line ending with `'%>'`.
   #
-  #   compiler = ERB::Compiler.new('<>')
-  #   code, enc = compiler.compile("Got <%= obj %>!\n")
-  #   puts code
+  # Other values allow [newline control][newline control]:
   #
-  # <i>Generates</i>:
+  # - `'>'`: Omit newline for each line ending with `'%>'`.
+  # - `'<>'`: Omit newline for each line starting with `'<%'` and ending with `'%>'`.
   #
-  #   #coding:UTF-8
-  #   print "Got "; print(( obj ).to_s); print "!\n"
+  # You can also [combine trim modes][combine trim modes].
   #
-  # == Evaluation
+  # **Keyword Argument `eoutvar`**
   #
-  # The compiled code can be used in any context where the names in the code
-  # correctly resolve. Using the last example, each of these print 'Got It!'
+  # The string value of keyword argument `eoutvar` specifies the name of the variable
+  # that method #result uses to construct its result string;
+  # see #src.
   #
-  # Evaluate using a variable:
+  # This is useful when you need to run multiple \ERB templates through the same binding
+  # and/or when you want to control where output ends up.
   #
-  #   obj = 'It'
-  #   eval code
+  # It's good practice to choose a variable name that begins with an underscore: `'_'`.
   #
-  # Evaluate using an input:
+  # [blank line control]: rdoc-ref:ERB@Suppressing+Unwanted+Blank+Lines
+  # [combine trim modes]: rdoc-ref:ERB@Combining+Trim+Modes
+  # [newline control]: rdoc-ref:ERB@Suppressing+Unwanted+Newlines
+  # [shorthand format]: rdoc-ref:ERB@Shorthand+Format+for+Execution+Tags
   #
-  #   mod = Module.new
-  #   mod.module_eval %{
-  #     def get(obj)
-  #       #{code}
-  #     end
-  #   }
-  #   extend mod
-  #   get('It')
+  def initialize(str, trim_mode: nil, eoutvar: '_erbout')
+    compiler = make_compiler(trim_mode)
+    set_eoutvar(compiler, eoutvar)
+    @src, @encoding, @frozen_string = *compiler.compile(str)
+    @src.freeze
+    @filename = nil
+    @lineno = 0
+    @_init = self.class.singleton_class
+  end
+
+  # :markup: markdown
   #
-  # Evaluate using an accessor:
+  # :call-seq:
+  #   make_compiler -> erb_compiler
   #
-  #   klass = Class.new Object
-  #   klass.class_eval %{
-  #     attr_accessor :obj
-  #     def initialize(obj)
-  #       @obj = obj
-  #     end
-  #     def get_it
-  #       #{code}
-  #     end
-  #   }
-  #   klass.new('It').get_it
+  # Returns a new ERB::Compiler with the given `trim_mode`;
+  # for `trim_mode` values, see ERB.new:
   #
-  # Good! See also ERB#def_method, ERB#def_module, and ERB#def_class.
-  class Compiler # :nodoc:
-    class PercentLine # :nodoc:
-      def initialize(str)
-        @value = str
-      end
-      attr_reader :value
-      alias :to_s :value
-
-      def empty?
-        @value.empty?
-      end
-    end
-
-    class Scanner # :nodoc:
-      @scanner_map = {}
-      def self.regist_scanner(klass, trim_mode, percent)
-        @scanner_map[[trim_mode, percent]] = klass
-      end
-
-      def self.default_scanner=(klass)
-        @default_scanner = klass
-      end
-
-      def self.make_scanner(src, trim_mode, percent)
-        klass = @scanner_map.fetch([trim_mode, percent], @default_scanner)
-        klass.new(src, trim_mode, percent)
-      end
-
-      def initialize(src, trim_mode, percent)
-        @src = src
-        @stag = nil
-      end
-      attr_accessor :stag
-
-      def scan; end
-    end
-
-    class TrimScanner < Scanner # :nodoc:
-      def initialize(src, trim_mode, percent)
-        super
-        @trim_mode = trim_mode
-        @percent = percent
-        if @trim_mode == '>'
-          @scan_line = self.method(:trim_line1)
-        elsif @trim_mode == '<>'
-          @scan_line = self.method(:trim_line2)
-        elsif @trim_mode == '-'
-          @scan_line = self.method(:explicit_trim_line)
-        else
-          @scan_line = self.method(:scan_line)
-        end
-      end
-      attr_accessor :stag
-
-      def scan(&block)
-        @stag = nil
-        if @percent
-          @src.each_line do |line|
-            percent_line(line, &block)
-          end
-        else
-          @scan_line.call(@src, &block)
-        end
-        nil
-      end
-
-      def percent_line(line, &block)
-        if @stag || line[0] != ?%
-          return @scan_line.call(line, &block)
-        end
-
-        line[0] = ''
-        if line[0] == ?%
-          @scan_line.call(line, &block)
-        else
-          yield(PercentLine.new(line.chomp))
-        end
-      end
-
-      def scan_line(line)
-        line.scan(/(.*?)(<%%|%%>|<%=|<%#|<%|%>|\n|\z)/m) do |tokens|
-          tokens.each do |token|
-            next if token.empty?
-            yield(token)
-          end
-        end
-      end
-
-      def trim_line1(line)
-        line.scan(/(.*?)(<%%|%%>|<%=|<%#|<%|%>\n|%>|\n|\z)/m) do |tokens|
-          tokens.each do |token|
-            next if token.empty?
-            if token == "%>\n"
-              yield('%>')
-              yield(:cr)
-            else
-              yield(token)
-            end
-          end
-        end
-      end
-
-      def trim_line2(line)
-        head = nil
-        line.scan(/(.*?)(<%%|%%>|<%=|<%#|<%|%>\n|%>|\n|\z)/m) do |tokens|
-          tokens.each do |token|
-            next if token.empty?
-            head = token unless head
-            if token == "%>\n"
-              yield('%>')
-              if is_erb_stag?(head)
-                yield(:cr)
-              else
-                yield("\n")
-              end
-              head = nil
-            else
-              yield(token)
-              head = nil if token == "\n"
-            end
-          end
-        end
-      end
-
-      def explicit_trim_line(line)
-        line.scan(/(.*?)(^[ \t]*<%\-|<%\-|<%%|%%>|<%=|<%#|<%|-%>\n|-%>|%>|\z)/m) do |tokens|
-          tokens.each do |token|
-            next if token.empty?
-            if @stag.nil? && /[ \t]*<%-/ =~ token
-              yield('<%')
-            elsif @stag && token == "-%>\n"
-              yield('%>')
-              yield(:cr)
-            elsif @stag && token == '-%>'
-              yield('%>')
-            else
-              yield(token)
-            end
-          end
-        end
-      end
-
-      ERB_STAG = %w(<%= <%# <%)
-      def is_erb_stag?(s)
-        ERB_STAG.member?(s)
-      end
-    end
-
-    Scanner.default_scanner = TrimScanner
-
-    class SimpleScanner < Scanner # :nodoc:
-      def scan
-        @src.scan(/(.*?)(<%%|%%>|<%=|<%#|<%|%>|\n|\z)/m) do |tokens|
-          tokens.each do |token|
-            next if token.empty?
-            yield(token)
-          end
-        end
-      end
-    end
-
-    Scanner.regist_scanner(SimpleScanner, nil, false)
-
-    begin
-      require 'strscan'
-      class SimpleScanner2 < Scanner # :nodoc:
-        def scan
-          stag_reg = /(.*?)(<%%|<%=|<%#|<%|\z)/m
-          etag_reg = /(.*?)(%%>|%>|\z)/m
-          scanner = StringScanner.new(@src)
-          while ! scanner.eos?
-            scanner.scan(@stag ? etag_reg : stag_reg)
-            yield(scanner[1])
-            yield(scanner[2])
-          end
-        end
-      end
-      Scanner.regist_scanner(SimpleScanner2, nil, false)
-
-      class ExplicitScanner < Scanner # :nodoc:
-        def scan
-          stag_reg = /(.*?)(^[ \t]*<%-|<%%|<%=|<%#|<%-|<%|\z)/m
-          etag_reg = /(.*?)(%%>|-%>|%>|\z)/m
-          scanner = StringScanner.new(@src)
-          while ! scanner.eos?
-            scanner.scan(@stag ? etag_reg : stag_reg)
-            yield(scanner[1])
-
-            elem = scanner[2]
-            if /[ \t]*<%-/ =~ elem
-              yield('<%')
-            elsif elem == '-%>'
-              yield('%>')
-              yield(:cr) if scanner.scan(/(\n|\z)/)
-            else
-              yield(elem)
-            end
-          end
-        end
-      end
-      Scanner.regist_scanner(ExplicitScanner, '-', false)
-
-    rescue LoadError
-    end
-
-    class Buffer # :nodoc:
-      def initialize(compiler, enc=nil)
-        @compiler = compiler
-        @line = []
-        @script = enc ? "#coding:#{enc.to_s}\n" : ""
-        @compiler.pre_cmd.each do |x|
-          push(x)
-        end
-      end
-      attr_reader :script
-
-      def push(cmd)
-        @line << cmd
-      end
-
-      def cr
-        @script << (@line.join('; '))
-        @line = []
-        @script << "\n"
-      end
-
-      def close
-        return unless @line
-        @compiler.post_cmd.each do |x|
-          push(x)
-        end
-        @script << (@line.join('; '))
-        @line = nil
-      end
-    end
-
-    def content_dump(s) # :nodoc:
-      n = s.count("\n")
-      if n > 0
-        s.dump + "\n" * n
-      else
-        s.dump
-      end
-    end
-
-    # Compiles an ERB template into Ruby code.  Returns an array of the code
-    # and encoding like ["code", Encoding].
-    def compile(s)
-      enc = s.encoding
-      raise ArgumentError, "#{enc} is not ASCII compatible" if enc.dummy?
-      s = s.dup.force_encoding("ASCII-8BIT") # don't use constant Enoding::ASCII_8BIT for miniruby
-      enc = detect_magic_comment(s) || enc
-      out = Buffer.new(self, enc)
-
-      content = ''
-      scanner = make_scanner(s)
-      scanner.scan do |token|
-        next if token.nil?
-        next if token == ''
-        if scanner.stag.nil?
-          case token
-          when PercentLine
-            out.push("#{@put_cmd} #{content_dump(content)}") if content.size > 0
-            content = ''
-            out.push(token.to_s)
-            out.cr
-          when :cr
-            out.cr
-          when '<%', '<%=', '<%#'
-            scanner.stag = token
-            out.push("#{@put_cmd} #{content_dump(content)}") if content.size > 0
-            content = ''
-          when "\n"
-            content << "\n"
-            out.push("#{@put_cmd} #{content_dump(content)}")
-            content = ''
-          when '<%%'
-            content << '<%'
-          else
-            content << token
-          end
-        else
-          case token
-          when '%>'
-            case scanner.stag
-            when '<%'
-              if content[-1] == ?\n
-                content.chop!
-                out.push(content)
-                out.cr
-              else
-                out.push(content)
-              end
-            when '<%='
-              out.push("#{@insert_cmd}((#{content}).to_s)")
-            when '<%#'
-              # out.push("# #{content_dump(content)}")
-            end
-            scanner.stag = nil
-            content = ''
-          when '%%>'
-            content << '%>'
-          else
-            content << token
-          end
-        end
-      end
-      out.push("#{@put_cmd} #{content_dump(content)}") if content.size > 0
-      out.close
-      return out.script, enc
-    end
-
-    def prepare_trim_mode(mode) # :nodoc:
-      case mode
-      when 1
-        return [false, '>']
-      when 2
-        return [false, '<>']
-      when 0
-        return [false, nil]
-      when String
-        perc = mode.include?('%')
-        if mode.include?('-')
-          return [perc, '-']
-        elsif mode.include?('<>')
-          return [perc, '<>']
-        elsif mode.include?('>')
-          return [perc, '>']
-        else
-          [perc, nil]
-        end
-      else
-        return [false, nil]
-      end
-    end
-
-    def make_scanner(src) # :nodoc:
-      Scanner.make_scanner(src, @trim_mode, @percent)
-    end
-
-    # Construct a new compiler using the trim_mode. See ERB#new for available
-    # trim modes.
-    def initialize(trim_mode)
-      @percent, @trim_mode = prepare_trim_mode(trim_mode)
-      @put_cmd = 'print'
-      @insert_cmd = @put_cmd
-      @pre_cmd = []
-      @post_cmd = []
-    end
-    attr_reader :percent, :trim_mode
-
-    # The command to handle text that ends with a newline
-    attr_accessor :put_cmd
-
-    # The command to handle text that is inserted prior to a newline
-    attr_accessor :insert_cmd
-
-    # An array of commands prepended to compiled code
-    attr_accessor :pre_cmd
-
-    # An array of commands appended to compiled code
-    attr_accessor :post_cmd
-
-    private
-    def detect_magic_comment(s)
-      if /\A<%#(.*)%>/ =~ s or (@percent and /\A%#(.*)/ =~ s)
-        comment = $1
-        comment = $1 if comment[/-\*-\s*(.*?)\s*-*-$/]
-        if %r"coding\s*[=:]\s*([[:alnum:]\-_]+)" =~ comment
-          enc = $1.sub(/-(?:mac|dos|unix)/i, '')
-          enc = Encoding.find(enc)
-        end
-      end
-    end
+  # ```
+  # ERB.new('').make_compiler(nil)
+  # # => #<ERB::Compiler:0x000001cff9467678 @insert_cmd="print", @percent=false, @post_cmd=[], @pre_cmd=[], @put_cmd="print", @trim_mode=nil>
+  # ```
+  #
+  def make_compiler(trim_mode)
+    ERB::Compiler.new(trim_mode)
   end
-end
 
-#--
-# ERB
-class ERB
+  # :markup: markdown
   #
-  # Constructs a new ERB object with the template specified in _str_.
+  # Returns the Ruby code that, when executed, generates the result;
+  # the code is executed by method #result,
+  # and by its wrapper methods #result_with_hash and #run:
   #
-  # An ERB object works by building a chunk of Ruby code that will output
-  # the completed template when run. If _safe_level_ is set to a non-nil value,
-  # ERB code will be run in a separate thread with <b>$SAFE</b> set to the
-  # provided level.
+  # ```
+  # template = 'The time is <%= Time.now %>.'
+  # erb = ERB.new(template)
+  # erb.src
+  # # => "#coding:UTF-8\n_erbout = +''; _erbout.<< \"The time is \".freeze; _erbout.<<(( Time.now ).to_s); _erbout.<< \".\".freeze; _erbout"
+  # erb.result
+  # # => "The time is 2025-09-18 15:58:08 -0500."
+  # ```
   #
-  # If _trim_mode_ is passed a String containing one or more of the following
-  # modifiers, ERB will adjust its code generation as listed:
+  # In a more readable format:
   #
-  #     %  enables Ruby code processing for lines beginning with %
-  #     <> omit newline for lines starting with <% and ending in %>
-  #     >  omit newline for lines ending in %>
+  # ```
+  #   # puts erb.src.split('; ')
+  #   # #coding:UTF-8
+  #   # _erbout = +''
+  #   # _erbout.<< "The time is ".freeze
+  #   # _erbout.<<(( Time.now ).to_s)
+  #   # _erbout.<< ".".freeze
+  #   # _erbout
+  # ```
   #
-  # _eoutvar_ can be used to set the name of the variable ERB will build up
-  # its output in.  This is useful when you need to run multiple ERB
-  # templates through the same binding and/or when you want to control where
-  # output ends up.  Pass the name of the variable to be used inside a String.
+  # Variable `_erbout` is used to store the intermediate results in the code;
+  # the name `_erbout` is the default in ERB.new,
+  # and can be changed via keyword argument `eoutvar`:
   #
-  # === Example
+  # ```
+  # erb = ERB.new(template, eoutvar: '_foo')
+  # puts template.src.split('; ')
+  # #coding:UTF-8
+  # _foo = +''
+  # _foo.<< "The time is ".freeze
+  # _foo.<<(( Time.now ).to_s)
+  # _foo.<< ".".freeze
+  # _foo
+  # ```
   #
-  #  require "erb"
+  attr_reader :src
+
+  # :markup: markdown
   #
-  #  # build data class
-  #  class Listings
-  #    PRODUCT = { :name => "Chicken Fried Steak",
-  #                :desc => "A well messages pattie, breaded and fried.",
-  #                :cost => 9.95 }
+  # Returns the encoding of `self`;
+  # see [Encodings][encodings]:
   #
-  #    attr_reader :product, :price
+  # [encodings]: rdoc-ref:ERB@Encodings
   #
-  #    def initialize( product = "", price = "" )
-  #      @product = product
-  #      @price = price
-  #    end
+  attr_reader :encoding
+
+  # :markup: markdown
   #
-  #    def build
-  #      b = binding
-  #      # create and run templates, filling member data variables
-  #      ERB.new(<<-'END_PRODUCT'.gsub(/^\s+/, ""), 0, "", "@product").result b
-  #        <%= PRODUCT[:name] %>
-  #        <%= PRODUCT[:desc] %>
-  #      END_PRODUCT
-  #      ERB.new(<<-'END_PRICE'.gsub(/^\s+/, ""), 0, "", "@price").result b
-  #        <%= PRODUCT[:name] %> -- <%= PRODUCT[:cost] %>
-  #        <%= PRODUCT[:desc] %>
-  #      END_PRICE
-  #    end
-  #  end
+  # Sets or returns the file name to be used in reporting errors;
+  # see [Error Reporting][error reporting].
   #
-  #  # setup template data
-  #  listings = Listings.new
-  #  listings.build
+  # [error reporting]: rdoc-ref:ERB@Error+Reporting
+  attr_accessor :filename
+
+  # :markup: markdown
   #
-  #  puts listings.product + "\n" + listings.price
+  # Sets or returns the line number to be used in reporting errors;
+  # see [Error Reporting][error reporting].
   #
-  # _Generates_
+  # [error reporting]: rdoc-ref:ERB@Error+Reporting
+  attr_accessor :lineno
+
+  # :markup: markdown
   #
-  #  Chicken Fried Steak
-  #  A well messages pattie, breaded and fried.
+  # :call-seq:
+  #   location = [filename, lineno] => [filename, lineno]
+  #   location = filename -> filename
   #
-  #  Chicken Fried Steak -- 9.95
-  #  A well messages pattie, breaded and fried.
+  # Sets the values of #filename and, if given, #lineno;
+  # see [Error Reporting][error reporting].
   #
-  def initialize(str, safe_level=nil, trim_mode=nil, eoutvar='_erbout')
-    @safe_level = safe_level
-    compiler = ERB::Compiler.new(trim_mode)
-    set_eoutvar(compiler, eoutvar)
-    @src, @enc = *compiler.compile(str)
-    @filename = nil
+  # [error reporting]: rdoc-ref:ERB@Error+Reporting
+  def location=((filename, lineno))
+    @filename = filename
+    @lineno = lineno if lineno
   end
 
-  # The Ruby code generated by ERB
-  attr_reader :src
-
-  # The optional _filename_ argument passed to Kernel#eval when the ERB code
-  # is run
-  attr_accessor :filename
-
+  # :markup: markdown
   #
-  # Can be used to set _eoutvar_ as described in ERB#new.  It's probably easier
-  # to just use the constructor though, since calling this method requires the
-  # setup of an ERB _compiler_ object.
+  # :call-seq:
+  #   set_eoutvar(compiler, eoutvar = '_erbout') -> [eoutvar]
+  #
+  # Sets the `eoutvar` value in the ERB::Compiler object `compiler`;
+  # returns a 1-element array containing the value of `eoutvar`:
+  #
+  # ```
+  # template = ERB.new('')
+  # compiler = template.make_compiler(nil)
+  # pp compiler
+  # #<ERB::Compiler:0x000001cff8a9aa00
+  #  @insert_cmd="print",
+  #  @percent=false,
+  #  @post_cmd=[],
+  #  @pre_cmd=[],
+  #  @put_cmd="print",
+  #  @trim_mode=nil>
+  # template.set_eoutvar(compiler, '_foo') # => ["_foo"]
+  # pp compiler
+  # #<ERB::Compiler:0x000001cff8a9aa00
+  #  @insert_cmd="_foo.<<",
+  #  @percent=false,
+  #  @post_cmd=["_foo"],
+  #  @pre_cmd=["_foo = +''"],
+  #  @put_cmd="_foo.<<",
+  #  @trim_mode=nil>
+  # ```
   #
   def set_eoutvar(compiler, eoutvar = '_erbout')
-    compiler.put_cmd = "#{eoutvar}.concat"
-    compiler.insert_cmd = "#{eoutvar}.concat"
-
-    cmd = []
-    cmd.push "#{eoutvar} = ''"
-
-    compiler.pre_cmd = cmd
+    compiler.put_cmd = "#{eoutvar}.<<"
+    compiler.insert_cmd = "#{eoutvar}.<<"
+    compiler.pre_cmd = ["#{eoutvar} = +''"]
+    compiler.post_cmd = [eoutvar]
+  end
 
-    cmd = []
-    cmd.push("#{eoutvar}.force_encoding(__ENCODING__)")
+  # :markup: markdown
+  #
+  # :call-seq:
+  #   run(binding = new_toplevel) -> nil
+  #
+  # Like #result, but prints the result string (instead of returning it);
+  # returns `nil`.
+  def run(b=new_toplevel)
+    print self.result(b)
+  end
 
-    compiler.post_cmd = cmd
+  # :markup: markdown
+  #
+  # :call-seq:
+  #   result(binding = new_toplevel) -> new_string
+  #
+  # Returns the string result formed by processing \ERB tags found in the stored template in `self`.
+  #
+  # With no argument given, uses the default binding;
+  # see [Default Binding][default binding].
+  #
+  # With argument `binding` given, uses the local binding;
+  # see [Local Binding][local binding].
+  #
+  # See also #result_with_hash.
+  #
+  # [default binding]: rdoc-ref:ERB@Default+Binding
+  # [local binding]: rdoc-ref:ERB@Local+Binding
+  #
+  def result(b=new_toplevel)
+    unless @_init.equal?(self.class.singleton_class)
+      raise ArgumentError, "not initialized"
+    end
+    eval(@src, b, (@filename || '(erb)'), @lineno)
   end
 
-  # Generate results and print them. (see ERB#result)
-  def run(b=TOPLEVEL_BINDING)
-    print self.result(b)
+  # :markup: markdown
+  #
+  # :call-seq:
+  #   result_with_hash(hash) -> new_string
+  #
+  # Returns the string result formed by processing \ERB tags found in the stored string in `self`;
+  # see [Augmented Binding][augmented binding].
+  #
+  # See also #result.
+  #
+  # [augmented binding]: rdoc-ref:ERB@Augmented+Binding
+  #
+  def result_with_hash(hash)
+    b = new_toplevel(hash.keys)
+    hash.each_pair do |key, value|
+      b.local_variable_set(key, value)
+    end
+    result(b)
   end
 
+  # :markup: markdown
+  #
+  # :call-seq:
+  #   new_toplevel(symbols) -> new_binding
   #
-  # Executes the generated ERB code to produce a completed template, returning
-  # the results of that code.  (See ERB#new for details on how this process can
-  # be affected by _safe_level_.)
-  #
-  # _b_ accepts a Binding or Proc object which is used to set the context of
-  # code evaluation.
-  #
-  def result(b=TOPLEVEL_BINDING)
-    if @safe_level
-      proc {
-        $SAFE = @safe_level
-        eval(@src, b, (@filename || '(erb)'), 0)
-      }.call
-    else
-      eval(@src, b, (@filename || '(erb)'), 0)
+  # Returns a new binding based on `TOPLEVEL_BINDING`;
+  # used to create a default binding for a call to #result.
+  #
+  # See [Default Binding][default binding].
+  #
+  # Argument `symbols` is an array of symbols;
+  # each symbol `symbol` is defined as a new variable to hide and
+  # prevent it from overwriting a variable of the same name already
+  # defined within the binding.
+  #
+  # [default binding]: rdoc-ref:ERB@Default+Binding
+  def new_toplevel(vars = nil)
+    b = TOPLEVEL_BINDING
+    if vars
+      vars = vars.select {|v| b.local_variable_defined?(v)}
+      unless vars.empty?
+        return b.eval("tap {|;#{vars.join(',')}| break binding}")
+      end
     end
+    b.dup
   end
+  private :new_toplevel
 
-  # Define _methodname_ as instance method of _mod_ from compiled ruby source.
+  # :markup: markdown
+  #
+  # :call-seq:
+  #   def_method(module, method_signature, filename = '(ERB)') -> method_name
+  #
+  # Creates and returns a new instance method in the given module `module`;
+  # returns the method name as a symbol.
+  #
+  # The method is created from the given `method_signature`,
+  # which consists of the method name and its argument names (if any).
+  #
+  # The `filename` sets the value of #filename;
+  # see [Error Reporting][error reporting].
+  #
+  # [error reporting]: rdoc-ref:ERB@Error+Reporting
+  #
+  # ```
+  # template = '<%= arg1 %> <%= arg2 %>'
+  # erb = ERB.new(template)
+  # MyModule = Module.new
+  # erb.def_method(MyModule, 'render(arg1, arg2)') # => :render
+  # class MyClass; include MyModule; end
+  # MyClass.new.render('foo', 123)                      # => "foo 123"
+  # ```
   #
-  # example:
-  #   filename = 'example.rhtml'   # 'arg1' and 'arg2' are used in example.rhtml
-  #   erb = ERB.new(File.read(filename))
-  #   erb.def_method(MyClass, 'render(arg1, arg2)', filename)
-  #   print MyClass.new.render('foo', 123)
   def def_method(mod, methodname, fname='(ERB)')
-    src = self.src
-    magic_comment = "#coding:#{@enc}\n"
+    unless @_init.equal?(self.class.singleton_class)
+      raise ArgumentError, "not initialized"
+    end
+    src = self.src.sub(/^(?!#|$)/) {"def #{methodname}\n"} << "\nend\n"
     mod.module_eval do
-      eval(magic_comment + "def #{methodname}\n" + src + "\nend\n", binding, fname, -2)
+      eval(src, binding, fname, -1)
     end
   end
 
-  # Create unnamed module, define _methodname_ as instance method of it, and return it.
-  #
-  # example:
-  #   filename = 'example.rhtml'   # 'arg1' and 'arg2' are used in example.rhtml
-  #   erb = ERB.new(File.read(filename))
-  #   erb.filename = filename
-  #   MyModule = erb.def_module('render(arg1, arg2)')
-  #   class MyClass
-  #     include MyModule
-  #   end
+  # :markup: markdown
+  #
+  # :call-seq:
+  #    def_module(method_name = 'erb') -> new_module
+  #
+  # Returns a new nameless module that has instance method `method_name`.
+  #
+  # ```
+  # template = '<%= arg1 %> <%= arg2 %>'
+  # erb = ERB.new(template)
+  # MyModule = template.def_module('render(arg1, arg2)')
+  # class MyClass
+  #   include MyModule
+  # end
+  # MyClass.new.render('foo', 123)
+  # # => "foo 123"
+  # ```
+  #
   def def_module(methodname='erb')
     mod = Module.new
     def_method(mod, methodname, @filename || '(ERB)')
     mod
   end
 
-  # Define unnamed class which has _methodname_ as instance method, and return it.
+  # :markup: markdown
   #
-  # example:
-  #   class MyClass_
-  #     def initialize(arg1, arg2)
-  #       @arg1 = arg1;  @arg2 = arg2
-  #     end
-  #   end
-  #   filename = 'example.rhtml'  # @arg1 and @arg2 are used in example.rhtml
-  #   erb = ERB.new(File.read(filename))
-  #   erb.filename = filename
-  #   MyClass = erb.def_class(MyClass_, 'render()')
-  #   print MyClass.new('foo', 123).render()
-  def def_class(superklass=Object, methodname='result')
-    cls = Class.new(superklass)
-    def_method(cls, methodname, @filename || '(ERB)')
-    cls
-  end
-end
-
-#--
-# ERB::Util
-class ERB
-  # A utility module for conversion routines, often handy in HTML generation.
-  module Util
-    public
-    #
-    # A utility method for escaping HTML tag characters in _s_.
-    #
-    #   require "erb"
-    #   include ERB::Util
-    #
-    #   puts html_escape("is a > 0 & a < 10?")
-    #
-    # _Generates_
-    #
-    #   is a &gt; 0 &amp; a &lt; 10?
-    #
-    def html_escape(s)
-      s.to_s.gsub(/&/, "&amp;").gsub(/\"/, "&quot;").gsub(/>/, "&gt;").gsub(/</, "&lt;")
-    end
-    alias h html_escape
-    module_function :h
-    module_function :html_escape
-
-    #
-    # A utility method for encoding the String _s_ as a URL.
-    #
-    #   require "erb"
-    #   include ERB::Util
-    #
-    #   puts url_encode("Programming Ruby:  The Pragmatic Programmer's Guide")
-    #
-    # _Generates_
-    #
-    #   Programming%20Ruby%3A%20%20The%20Pragmatic%20Programmer%27s%20Guide
-    #
-    def url_encode(s)
-      s.to_s.dup.force_encoding("ASCII-8BIT").gsub(/[^a-zA-Z0-9_\-.]/n) {
-        sprintf("%%%02X", $&.unpack("C")[0])
-      }
-    end
-    alias u url_encode
-    module_function :u
-    module_function :url_encode
-  end
-end
-
-#--
-# ERB::DefMethod
-class ERB
-  # Utility module to define eRuby script as instance method.
-  #
-  # === Example
-  #
-  # example.rhtml:
-  #   <% for item in @items %>
-  #   <b><%= item %></b>
-  #   <% end %>
-  #
-  # example.rb:
-  #   require 'erb'
-  #   class MyClass
-  #     extend ERB::DefMethod
-  #     def_erb_method('render()', 'example.rhtml')
-  #     def initialize(items)
-  #       @items = items
-  #     end
+  # :call-seq:
+  #   def_class(super_class = Object, method_name = 'result') -> new_class
+  #
+  # Returns a new nameless class whose superclass is `super_class`,
+  # and which has instance method `method_name`.
+  #
+  # Create a template from HTML that has embedded expression tags that use `@arg1` and `@arg2`:
+  #
+  # ```
+  # html = <<TEMPLATE
+  # <html>
+  # <body>
+  #   <p><%= @arg1 %></p>
+  #   <p><%= @arg2 %></p>
+  # </body>
+  # </html>
+  # TEMPLATE
+  # template = ERB.new(html)
+  # ```
+  #
+  # Create a base class that has `@arg1` and `@arg2`:
+  #
+  # ```
+  # class MyBaseClass
+  #   def initialize(arg1, arg2)
+  #     @arg1 = arg1
+  #     @arg2 = arg2
   #   end
-  #   print MyClass.new([10,20,30]).render()
+  # end
+  # ```
   #
-  # result:
+  # Use method #def_class to create a subclass that has method `:render`:
   #
-  #   <b>10</b>
+  # ```
+  # MySubClass = template.def_class(MyBaseClass, :render)
+  # ```
   #
-  #   <b>20</b>
+  # Generate the result:
   #
-  #   <b>30</b>
+  # ```
+  # puts MySubClass.new('foo', 123).render
+  # <html>
+  # <body>
+  #   <p>foo</p>
+  #   <p>123</p>
+  # </body>
+  # </html>
+  # ```
   #
-  module DefMethod
-    public
-    # define _methodname_ as instance method of current module, using ERB
-    # object or eRuby file
-    def def_erb_method(methodname, erb_or_fname)
-      if erb_or_fname.kind_of? String
-        fname = erb_or_fname
-        erb = ERB.new(File.read(fname))
-        erb.def_method(self, methodname, fname)
-      else
-        erb = erb_or_fname
-        erb.def_method(self, methodname, erb.filename || '(ERB)')
-      end
-    end
-    module_function :def_erb_method
+  def def_class(superklass=Object, methodname='result')
+    cls = Class.new(superklass)
+    def_method(cls, methodname, @filename || '(ERB)')
+    cls
   end
 end
diff --git a/lib/erb/compiler.rb b/lib/erb/compiler.rb
new file mode 100644
index 0000000000..6d70288b4f
--- /dev/null
+++ b/lib/erb/compiler.rb
@@ -0,0 +1,487 @@
+# frozen_string_literal: true
+#--
+# ERB::Compiler
+#
+# Compiles ERB templates into Ruby code; the compiled code produces the
+# template result when evaluated. ERB::Compiler provides hooks to define how
+# generated output is handled.
+#
+# Internally ERB does something like this to generate the code returned by
+# ERB#src:
+#
+#   compiler = ERB::Compiler.new('<>')
+#   compiler.pre_cmd    = ["_erbout=+''"]
+#   compiler.put_cmd    = "_erbout.<<"
+#   compiler.insert_cmd = "_erbout.<<"
+#   compiler.post_cmd   = ["_erbout"]
+#
+#   code, enc = compiler.compile("Got <%= obj %>!\n")
+#   puts code
+#
+# <i>Generates</i>:
+#
+#   #coding:UTF-8
+#   _erbout=+''; _erbout.<< "Got ".freeze; _erbout.<<(( obj ).to_s); _erbout.<< "!\n".freeze; _erbout
+#
+# By default the output is sent to the print method.  For example:
+#
+#   compiler = ERB::Compiler.new('<>')
+#   code, enc = compiler.compile("Got <%= obj %>!\n")
+#   puts code
+#
+# <i>Generates</i>:
+#
+#   #coding:UTF-8
+#   print "Got ".freeze; print(( obj ).to_s); print "!\n".freeze
+#
+# == Evaluation
+#
+# The compiled code can be used in any context where the names in the code
+# correctly resolve. Using the last example, each of these print 'Got It!'
+#
+# Evaluate using a variable:
+#
+#   obj = 'It'
+#   eval code
+#
+# Evaluate using an input:
+#
+#   mod = Module.new
+#   mod.module_eval %{
+#     def get(obj)
+#       #{code}
+#     end
+#   }
+#   extend mod
+#   get('It')
+#
+# Evaluate using an accessor:
+#
+#   klass = Class.new Object
+#   klass.class_eval %{
+#     attr_accessor :obj
+#     def initialize(obj)
+#       @obj = obj
+#     end
+#     def get_it
+#       #{code}
+#     end
+#   }
+#   klass.new('It').get_it
+#
+# Good! See also ERB#def_method, ERB#def_module, and ERB#def_class.
+class ERB::Compiler # :nodoc:
+  class PercentLine # :nodoc:
+    def initialize(str)
+      @value = str
+    end
+    attr_reader :value
+    alias :to_s :value
+  end
+
+  class Scanner # :nodoc:
+    @scanner_map = defined?(Ractor) ? Ractor.make_shareable({}) : {}
+    class << self
+      if defined?(Ractor)
+        def register_scanner(klass, trim_mode, percent)
+          @scanner_map = Ractor.make_shareable({ **@scanner_map, [trim_mode, percent] => klass })
+        end
+      else
+        def register_scanner(klass, trim_mode, percent)
+          @scanner_map[[trim_mode, percent]] = klass
+        end
+      end
+      alias :regist_scanner :register_scanner
+    end
+
+    def self.default_scanner=(klass)
+      @default_scanner = klass
+    end
+
+    def self.make_scanner(src, trim_mode, percent)
+      klass = @scanner_map.fetch([trim_mode, percent], @default_scanner)
+      klass.new(src, trim_mode, percent)
+    end
+
+    DEFAULT_STAGS = %w(<%% <%= <%# <%).freeze
+    DEFAULT_ETAGS = %w(%%> %>).freeze
+    def initialize(src, trim_mode, percent)
+      @src = src
+      @stag = nil
+      @stags = DEFAULT_STAGS
+      @etags = DEFAULT_ETAGS
+    end
+    attr_accessor :stag
+    attr_reader :stags, :etags
+
+    def scan; end
+  end
+
+  class TrimScanner < Scanner # :nodoc:
+    def initialize(src, trim_mode, percent)
+      super
+      @trim_mode = trim_mode
+      @percent = percent
+      if @trim_mode == '>'
+        @scan_reg  = /(.*?)(%>\r?\n|#{(stags + etags).join('|')}|\n|\z)/m
+        @scan_line = self.method(:trim_line1)
+      elsif @trim_mode == '<>'
+        @scan_reg  = /(.*?)(%>\r?\n|#{(stags + etags).join('|')}|\n|\z)/m
+        @scan_line = self.method(:trim_line2)
+      elsif @trim_mode == '-'
+        @scan_reg  = /(.*?)(^[ \t]*<%\-|<%\-|-%>\r?\n|-%>|#{(stags + etags).join('|')}|\z)/m
+        @scan_line = self.method(:explicit_trim_line)
+      else
+        @scan_reg  = /(.*?)(#{(stags + etags).join('|')}|\n|\z)/m
+        @scan_line = self.method(:scan_line)
+      end
+    end
+
+    def scan(&block)
+      @stag = nil
+      if @percent
+        @src.each_line do |line|
+          percent_line(line, &block)
+        end
+      else
+        @scan_line.call(@src, &block)
+      end
+      nil
+    end
+
+    def percent_line(line, &block)
+      if @stag || line[0] != ?%
+        return @scan_line.call(line, &block)
+      end
+
+      line[0] = ''
+      if line[0] == ?%
+        @scan_line.call(line, &block)
+      else
+        yield(PercentLine.new(line.chomp))
+      end
+    end
+
+    def scan_line(line)
+      line.scan(@scan_reg) do |tokens|
+        tokens.each do |token|
+          next if token.empty?
+          yield(token)
+        end
+      end
+    end
+
+    def trim_line1(line)
+      line.scan(@scan_reg) do |tokens|
+        tokens.each do |token|
+          next if token.empty?
+          if token == "%>\n" || token == "%>\r\n"
+            yield('%>')
+            yield(:cr)
+          else
+            yield(token)
+          end
+        end
+      end
+    end
+
+    def trim_line2(line)
+      head = nil
+      line.scan(@scan_reg) do |tokens|
+        tokens.each do |token|
+          next if token.empty?
+          head = token unless head
+          if token == "%>\n" || token == "%>\r\n"
+            yield('%>')
+            if is_erb_stag?(head)
+              yield(:cr)
+            else
+              yield("\n")
+            end
+            head = nil
+          else
+            yield(token)
+            head = nil if token == "\n"
+          end
+        end
+      end
+    end
+
+    def explicit_trim_line(line)
+      line.scan(@scan_reg) do |tokens|
+        tokens.each do |token|
+          next if token.empty?
+          if @stag.nil? && /[ \t]*<%-/ =~ token
+            yield('<%')
+          elsif @stag && (token == "-%>\n" || token == "-%>\r\n")
+            yield('%>')
+            yield(:cr)
+          elsif @stag && token == '-%>'
+            yield('%>')
+          else
+            yield(token)
+          end
+        end
+      end
+    end
+
+    ERB_STAG = %w(<%= <%# <%).freeze
+    def is_erb_stag?(s)
+      ERB_STAG.member?(s)
+    end
+  end
+
+  Scanner.default_scanner = TrimScanner
+
+  begin
+    require 'strscan'
+  rescue LoadError
+  else
+    class SimpleScanner < Scanner # :nodoc:
+      def scan
+        stag_reg = (stags == DEFAULT_STAGS) ? /(.*?)(<%[%=#]?|\z)/m : /(.*?)(#{stags.join('|')}|\z)/m
+        etag_reg = (etags == DEFAULT_ETAGS) ? /(.*?)(%%?>|\z)/m : /(.*?)(#{etags.join('|')}|\z)/m
+        scanner = StringScanner.new(@src)
+        while ! scanner.eos?
+          scanner.scan(@stag ? etag_reg : stag_reg)
+          yield(scanner[1])
+          yield(scanner[2])
+        end
+      end
+    end
+    Scanner.register_scanner(SimpleScanner, nil, false)
+
+    class ExplicitScanner < Scanner # :nodoc:
+      def scan
+        stag_reg = /(.*?)(^[ \t]*<%-|<%-|#{stags.join('|')}|\z)/m
+        etag_reg = /(.*?)(-%>|#{etags.join('|')}|\z)/m
+        scanner = StringScanner.new(@src)
+        while ! scanner.eos?
+          scanner.scan(@stag ? etag_reg : stag_reg)
+          yield(scanner[1])
+
+          elem = scanner[2]
+          if /[ \t]*<%-/ =~ elem
+            yield('<%')
+          elsif elem == '-%>'
+            yield('%>')
+            yield(:cr) if scanner.scan(/(\r?\n|\z)/)
+          else
+            yield(elem)
+          end
+        end
+      end
+    end
+    Scanner.register_scanner(ExplicitScanner, '-', false)
+  end
+
+  class Buffer # :nodoc:
+    def initialize(compiler, enc=nil, frozen=nil)
+      @compiler = compiler
+      @line = []
+      @script = +''
+      @script << "#coding:#{enc}\n" if enc
+      @script << "#frozen-string-literal:#{frozen}\n" unless frozen.nil?
+      @compiler.pre_cmd.each do |x|
+        push(x)
+      end
+    end
+    attr_reader :script
+
+    def push(cmd)
+      @line << cmd
+    end
+
+    def cr
+      @script << (@line.join('; '))
+      @line = []
+      @script << "\n"
+    end
+
+    def close
+      return unless @line
+      @compiler.post_cmd.each do |x|
+        push(x)
+      end
+      @script << (@line.join('; '))
+      @line = nil
+    end
+  end
+
+  def add_put_cmd(out, content)
+    out.push("#{@put_cmd} #{content.dump}.freeze#{"\n" * content.count("\n")}")
+  end
+
+  def add_insert_cmd(out, content)
+    out.push("#{@insert_cmd}((#{content}).to_s)")
+  end
+
+  # Compiles an ERB template into Ruby code.  Returns an array of the code
+  # and encoding like ["code", Encoding].
+  def compile(s)
+    enc = s.encoding
+    raise ArgumentError, "#{enc} is not ASCII compatible" if enc.dummy?
+    s = s.b # see String#b
+    magic_comment = detect_magic_comment(s, enc)
+    out = Buffer.new(self, *magic_comment)
+
+    self.content = +''
+    scanner = make_scanner(s)
+    scanner.scan do |token|
+      next if token.nil?
+      next if token == ''
+      if scanner.stag.nil?
+        compile_stag(token, out, scanner)
+      else
+        compile_etag(token, out, scanner)
+      end
+    end
+    add_put_cmd(out, content) if content.size > 0
+    out.close
+    return out.script, *magic_comment
+  end
+
+  def compile_stag(stag, out, scanner)
+    case stag
+    when PercentLine
+      add_put_cmd(out, content) if content.size > 0
+      self.content = +''
+      out.push(stag.to_s)
+      out.cr
+    when :cr
+      out.cr
+    when '<%', '<%=', '<%#'
+      scanner.stag = stag
+      add_put_cmd(out, content) if content.size > 0
+      self.content = +''
+    when "\n"
+      content << "\n"
+      add_put_cmd(out, content)
+      self.content = +''
+    when '<%%'
+      content << '<%'
+    else
+      content << stag
+    end
+  end
+
+  def compile_etag(etag, out, scanner)
+    case etag
+    when '%>'
+      compile_content(scanner.stag, out)
+      scanner.stag = nil
+      self.content = +''
+    when '%%>'
+      content << '%>'
+    else
+      content << etag
+    end
+  end
+
+  def compile_content(stag, out)
+    case stag
+    when '<%'
+      if content[-1] == ?\n
+        content.chop!
+        out.push(content)
+        out.cr
+      else
+        out.push(content)
+      end
+    when '<%='
+      add_insert_cmd(out, content)
+    when '<%#'
+      out.push("\n" * content.count("\n")) # only adjust lineno
+    end
+  end
+
+  def prepare_trim_mode(mode) # :nodoc:
+    case mode
+    when 1
+      return [false, '>']
+    when 2
+      return [false, '<>']
+    when 0, nil
+      return [false, nil]
+    when String
+      unless mode.match?(/\A(%|-|>|<>){1,2}\z/)
+        warn_invalid_trim_mode(mode, uplevel: 5)
+      end
+
+      perc = mode.include?('%')
+      if mode.include?('-')
+        return [perc, '-']
+      elsif mode.include?('<>')
+        return [perc, '<>']
+      elsif mode.include?('>')
+        return [perc, '>']
+      else
+        [perc, nil]
+      end
+    else
+      warn_invalid_trim_mode(mode, uplevel: 5)
+      return [false, nil]
+    end
+  end
+
+  def make_scanner(src) # :nodoc:
+    Scanner.make_scanner(src, @trim_mode, @percent)
+  end
+
+  # Construct a new compiler using the trim_mode. See ERB::new for available
+  # trim modes.
+  def initialize(trim_mode)
+    @percent, @trim_mode = prepare_trim_mode(trim_mode)
+    @put_cmd = 'print'
+    @insert_cmd = @put_cmd
+    @pre_cmd = []
+    @post_cmd = []
+  end
+  attr_reader :percent, :trim_mode
+
+  # The command to handle text that ends with a newline
+  attr_accessor :put_cmd
+
+  # The command to handle text that is inserted prior to a newline
+  attr_accessor :insert_cmd
+
+  # An array of commands prepended to compiled code
+  attr_accessor :pre_cmd
+
+  # An array of commands appended to compiled code
+  attr_accessor :post_cmd
+
+  private
+
+  # A buffered text in #compile
+  attr_accessor :content
+
+  def detect_magic_comment(s, enc = nil)
+    re = @percent ? /\G(?:<%#(.*)%>|%#(.*)\n)/ : /\G<%#(.*)%>/
+    frozen = nil
+    s.scan(re) do
+      comment = $+
+      comment = $1 if comment[/-\*-\s*([^\s].*?)\s*-\*-$/]
+      case comment
+      when %r"coding\s*[=:]\s*([[:alnum:]\-_]+)"
+        enc = Encoding.find($1.sub(/-(?:mac|dos|unix)/i, ''))
+      when %r"frozen[-_]string[-_]literal\s*:\s*([[:alnum:]]+)"
+        frozen = $1
+      end
+    end
+    return enc, frozen
+  end
+
+  # :stopdoc:
+  WARNING_UPLEVEL = Class.new {
+    attr_reader :c
+    def initialize from
+      @c = caller.length - from.length
+    end
+  }.new(caller(0)).c
+  private_constant :WARNING_UPLEVEL
+
+  def warn_invalid_trim_mode(mode, uplevel:)
+    warn "Invalid ERB trim mode: #{mode.inspect} (trim_mode: nil, 0, 1, 2, or String composed of '%' and/or '-', '>', '<>')", uplevel: uplevel + WARNING_UPLEVEL
+  end
+end
diff --git a/lib/erb/def_method.rb b/lib/erb/def_method.rb
new file mode 100644
index 0000000000..e503b37140
--- /dev/null
+++ b/lib/erb/def_method.rb
@@ -0,0 +1,47 @@
+# frozen_string_literal: true
+
+# ERB::DefMethod
+#
+# Utility module to define eRuby script as instance method.
+#
+# === Example
+#
+# example.rhtml:
+#   <% for item in @items %>
+#   <b><%= item %></b>
+#   <% end %>
+#
+# example.rb:
+#   require 'erb'
+#   class MyClass
+#     extend ERB::DefMethod
+#     def_erb_method('render()', 'example.rhtml')
+#     def initialize(items)
+#       @items = items
+#     end
+#   end
+#   print MyClass.new([10,20,30]).render()
+#
+# result:
+#
+#   <b>10</b>
+#
+#   <b>20</b>
+#
+#   <b>30</b>
+#
+module ERB::DefMethod
+  # define _methodname_ as instance method of current module, using ERB
+  # object or eRuby file
+  def def_erb_method(methodname, erb_or_fname)
+    if erb_or_fname.kind_of? String
+      fname = erb_or_fname
+      erb = ERB.new(File.read(fname))
+      erb.def_method(self, methodname, fname)
+    else
+      erb = erb_or_fname
+      erb.def_method(self, methodname, erb.filename || '(ERB)')
+    end
+  end
+  module_function :def_erb_method
+end
diff --git a/lib/erb/erb.gemspec b/lib/erb/erb.gemspec
new file mode 100644
index 0000000000..70113a2a04
--- /dev/null
+++ b/lib/erb/erb.gemspec
@@ -0,0 +1,37 @@
+begin
+  require_relative 'lib/erb/version'
+rescue LoadError
+  # for Ruby core repository
+  require_relative 'version'
+end
+
+Gem::Specification.new do |spec|
+  spec.name          = 'erb'
+  spec.version       = ERB::VERSION
+  spec.authors       = ['Masatoshi SEKI', 'Takashi Kokubun']
+  spec.email         = ['seki@ruby-lang.org', 'k0kubun@ruby-lang.org']
+
+  spec.summary       = %q{An easy to use but powerful templating system for Ruby.}
+  spec.description   = %q{An easy to use but powerful templating system for Ruby.}
+  spec.homepage      = 'https://github.com/ruby/erb'
+  spec.licenses      = ['Ruby', 'BSD-2-Clause']
+
+  spec.metadata['homepage_uri'] = spec.homepage
+  spec.metadata['source_code_uri'] = spec.homepage
+  spec.metadata['changelog_uri'] = "https://github.com/ruby/erb/blob/v#{spec.version}/NEWS.md"
+
+  spec.files = Dir.chdir(__dir__) do
+    `git ls-files -z`.split("\x0").reject { |f| f.match(%r{^(test|\.git|\.github)/}) }
+  end
+  spec.bindir        = 'libexec'
+  spec.executables   = ['erb']
+  spec.require_paths = ['lib']
+
+  spec.required_ruby_version = '>= 3.2.0'
+
+  if RUBY_ENGINE == 'jruby'
+    spec.platform = 'java'
+  else
+    spec.extensions = ['ext/erb/escape/extconf.rb']
+  end
+end
diff --git a/lib/erb/util.rb b/lib/erb/util.rb
new file mode 100644
index 0000000000..d7d69eb4f1
--- /dev/null
+++ b/lib/erb/util.rb
@@ -0,0 +1,77 @@
+# frozen_string_literal: true
+
+# Load CGI.escapeHTML and CGI.escapeURIComponent.
+# CRuby:
+#   cgi.gem v0.1.0+ (Ruby 2.7-3.4) and Ruby 4.0+ stdlib have 'cgi/escape' and CGI.escapeHTML.
+#   cgi.gem v0.3.3+ (Ruby 3.2-3.4) and Ruby 4.0+ stdlib have CGI.escapeURIComponent.
+# JRuby: cgi.gem has a Java extension 'cgi/escape'.
+# TruffleRuby: lib/truffle/cgi/escape.rb requires 'cgi/util'.
+require 'cgi/escape'
+
+# Load or define ERB::Escape#html_escape.
+# We don't build the C extension 'cgi/escape' for JRuby, TruffleRuby, and WASM.
+# miniruby (used by CRuby build scripts) also fails to load erb/escape.so.
+begin
+  require 'erb/escape'
+rescue LoadError
+  # ERB::Escape
+  #
+  # A subset of ERB::Util. Unlike ERB::Util#html_escape, we expect/hope
+  # Rails will not monkey-patch ERB::Escape#html_escape.
+  module ERB::Escape
+    # :stopdoc:
+    def html_escape(s)
+      CGI.escapeHTML(s.to_s)
+    end
+    module_function :html_escape
+  end
+end
+
+# ERB::Util
+#
+# A utility module for conversion routines, often handy in HTML generation.
+module ERB::Util
+  #
+  # A utility method for escaping HTML tag characters in _s_.
+  #
+  #   require "erb"
+  #   include ERB::Util
+  #
+  #   puts html_escape("is a > 0 & a < 10?")
+  #
+  # _Generates_
+  #
+  #   is a &gt; 0 &amp; a &lt; 10?
+  #
+  include ERB::Escape # html_escape
+  module_function :html_escape
+  alias h html_escape
+  module_function :h
+
+  if CGI.respond_to?(:escapeURIComponent)
+    #
+    # A utility method for encoding the String _s_ as a URL.
+    #
+    #   require "erb"
+    #   include ERB::Util
+    #
+    #   puts url_encode("Programming Ruby:  The Pragmatic Programmer's Guide")
+    #
+    # _Generates_
+    #
+    #   Programming%20Ruby%3A%20%20The%20Pragmatic%20Programmer%27s%20Guide
+    #
+    def url_encode(s)
+      CGI.escapeURIComponent(s.to_s)
+    end
+  else # cgi.gem <= v0.3.2
+    def url_encode(s)
+      s.to_s.b.gsub(/[^a-zA-Z0-9_\-.~]/n) do |m|
+        sprintf("%%%02X", m.unpack1("C"))
+      end
+    end
+  end
+  alias u url_encode
+  module_function :u
+  module_function :url_encode
+end
diff --git a/lib/erb/version.rb b/lib/erb/version.rb
new file mode 100644
index 0000000000..fde4a2776a
--- /dev/null
+++ b/lib/erb/version.rb
@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+class ERB
+  # The string \ERB version.
+  VERSION = '6.0.4'
+end
diff --git a/lib/error_highlight.rb b/lib/error_highlight.rb
new file mode 100644
index 0000000000..31db95d11b
--- /dev/null
+++ b/lib/error_highlight.rb
@@ -0,0 +1,2 @@
+require_relative "error_highlight/base"
+require_relative "error_highlight/core_ext"
diff --git a/lib/error_highlight/base.rb b/lib/error_highlight/base.rb
new file mode 100644
index 0000000000..5fffe5ec34
--- /dev/null
+++ b/lib/error_highlight/base.rb
@@ -0,0 +1,938 @@
+require_relative "version"
+
+module ErrorHighlight
+  # Identify the code fragment where a given exception occurred.
+  #
+  # Options:
+  #
+  # point_type: :name | :args
+  #   :name (default) points to the method/variable name where the exception occurred.
+  #   :args points to the arguments of the method call where the exception occurred.
+  #
+  # backtrace_location: Thread::Backtrace::Location
+  #   It locates the code fragment of the given backtrace_location.
+  #   By default, it uses the first frame of backtrace_locations of the given exception.
+  #
+  # Returns:
+  #  {
+  #    first_lineno: Integer,
+  #    first_column: Integer,
+  #    last_lineno: Integer,
+  #    last_column: Integer,
+  #    snippet: String,
+  #    script_lines: [String],
+  #  } | nil
+  #
+  # Limitations:
+  #
+  # Currently, ErrorHighlight.spot only supports a single-line code fragment.
+  # Therefore, if the return value is not nil, first_lineno and last_lineno will have
+  # the same value. If the relevant code fragment spans multiple lines
+  # (e.g., Array#[] of <tt>ary[(newline)expr(newline)]</tt>), the method will return nil.
+  # This restriction may be removed in the future.
+  def self.spot(obj, **opts)
+    case obj
+    when Exception
+      exc = obj
+      loc = opts[:backtrace_location]
+      opts = { point_type: opts.fetch(:point_type, :name) }
+
+      unless loc
+        case exc
+        when TypeError, ArgumentError
+          opts[:point_type] = :args
+        end
+
+        locs = exc.backtrace_locations
+        return nil unless locs
+
+        loc = locs.first
+        return nil unless loc
+
+        opts[:name] = exc.name if NameError === obj
+      end
+
+      return nil unless Thread::Backtrace::Location === loc
+
+      node =
+        begin
+          RubyVM::AbstractSyntaxTree.of(loc, keep_script_lines: true)
+        rescue RuntimeError => error
+          # RubyVM::AbstractSyntaxTree.of raises an error with a message that
+          # includes "prism" when the ISEQ was compiled with the prism compiler.
+          # In this case, we'll try to parse again with prism instead.
+          raise unless error.message.include?("prism")
+          prism_find(loc)
+        end
+
+      Spotter.new(node, **opts).spot
+
+    when RubyVM::AbstractSyntaxTree::Node, Prism::Node
+      Spotter.new(obj, **opts).spot
+
+    else
+      raise TypeError, "Exception is expected"
+    end
+
+  rescue SyntaxError,
+         SystemCallError, # file not found or something
+         ArgumentError # eval'ed code
+
+    return nil
+  end
+
+  # Accepts a Thread::Backtrace::Location object and returns a Prism::Node
+  # corresponding to the backtrace location in the source code.
+  def self.prism_find(location)
+    require "prism"
+    return nil if Prism::VERSION < "1.0.0"
+
+    absolute_path = location.absolute_path
+    return unless absolute_path
+
+    node_id = RubyVM::AbstractSyntaxTree.node_id_for_backtrace_location(location)
+    Prism.parse_file(absolute_path).value.breadth_first_search { |node| node.node_id == node_id }
+  end
+
+  private_class_method :prism_find
+
+  class Spotter
+    class NonAscii < Exception; end
+    private_constant :NonAscii
+
+    def initialize(node, point_type: :name, name: nil)
+      @node = node
+      @point_type = point_type
+      @name = name
+
+      # Not-implemented-yet options
+      @arg = nil # Specify the index or keyword at which argument caused the TypeError/ArgumentError
+      @multiline = false # Allow multiline spot
+
+      @fetch = -> (lineno, last_lineno = lineno) do
+        snippet = @node.script_lines[lineno - 1 .. last_lineno - 1].join("")
+        snippet += "\n" unless snippet.end_with?("\n")
+
+        # It requires some work to support Unicode (or multibyte) characters.
+        # Tentatively, we stop highlighting if the code snippet has non-ascii characters.
+        # See https://github.com/ruby/error_highlight/issues/4
+        raise NonAscii unless snippet.ascii_only?
+
+        snippet
+      end
+    end
+
+    def spot
+      return nil unless @node
+
+      # In Ruby 3.2 or later, a nested constant access (like `Foo::Bar::Baz`)
+      # is compiled to one instruction (opt_getconstant_path).
+      # @node points to the node of the whole `Foo::Bar::Baz` even if `Foo`
+      # or `Foo::Bar` causes NameError.
+      # So we try to spot the sub-node that causes the NameError by using
+      # `NameError#name`.
+      case @node.type
+      when :COLON2
+        subnodes = []
+        node = @node
+        while node.type == :COLON2
+          node2, const = node.children
+          subnodes << node if const == @name
+          node = node2
+        end
+        if node.type == :CONST || node.type == :COLON3
+          if node.children.first == @name
+            subnodes << node
+          end
+
+          # If we found only one sub-node whose name is equal to @name, use it
+          return nil if subnodes.size != 1
+          @node = subnodes.first
+        else
+          # Do nothing; opt_getconstant_path is used only when the const base is
+          # NODE_CONST (`Foo`) or NODE_COLON3 (`::Foo`)
+        end
+      when :constant_path_node
+        subnodes = []
+        node = @node
+
+        begin
+          subnodes << node if node.name == @name
+        end while (node = node.parent).is_a?(Prism::ConstantPathNode)
+
+        if node.is_a?(Prism::ConstantReadNode) && node.name == @name
+          subnodes << node
+        end
+
+        # If we found only one sub-node whose name is equal to @name, use it
+        return nil if subnodes.size != 1
+        @node = subnodes.first
+      end
+
+      case @node.type
+
+      when :CALL, :QCALL
+        case @point_type
+        when :name
+          spot_call_for_name
+        when :args
+          spot_call_for_args
+        end
+
+      when :ATTRASGN
+        case @point_type
+        when :name
+          spot_attrasgn_for_name
+        when :args
+          spot_attrasgn_for_args
+        end
+
+      when :OPCALL
+        case @point_type
+        when :name
+          spot_opcall_for_name
+        when :args
+          spot_opcall_for_args
+        end
+
+      when :FCALL
+        case @point_type
+        when :name
+          spot_fcall_for_name
+        when :args
+          spot_fcall_for_args
+        end
+
+      when :VCALL
+        spot_vcall
+
+      when :OP_ASGN1
+        case @point_type
+        when :name
+          spot_op_asgn1_for_name
+        when :args
+          spot_op_asgn1_for_args
+        end
+
+      when :OP_ASGN2
+        case @point_type
+        when :name
+          spot_op_asgn2_for_name
+        when :args
+          spot_op_asgn2_for_args
+        end
+
+      when :CONST
+        spot_vcall
+
+      when :COLON2
+        spot_colon2
+
+      when :COLON3
+        spot_vcall
+
+      when :OP_CDECL
+        spot_op_cdecl
+
+      when :DEFN
+        raise NotImplementedError if @point_type != :name
+        spot_defn
+
+      when :DEFS
+        raise NotImplementedError if @point_type != :name
+        spot_defs
+
+      when :LAMBDA
+        spot_lambda
+
+      when :ITER
+        spot_iter
+
+      when :call_node
+        case @point_type
+        when :name
+          prism_spot_call_for_name
+        when :args
+          prism_spot_call_for_args
+        end
+
+      when :local_variable_operator_write_node
+        case @point_type
+        when :name
+          prism_spot_local_variable_operator_write_for_name
+        when :args
+          prism_spot_local_variable_operator_write_for_args
+        end
+
+      when :call_operator_write_node
+        case @point_type
+        when :name
+          prism_spot_call_operator_write_for_name
+        when :args
+          prism_spot_call_operator_write_for_args
+        end
+
+      when :index_operator_write_node
+        case @point_type
+        when :name
+          prism_spot_index_operator_write_for_name
+        when :args
+          prism_spot_index_operator_write_for_args
+        end
+
+      when :constant_read_node
+        prism_spot_constant_read
+
+      when :constant_path_node
+        prism_spot_constant_path
+
+      when :constant_path_operator_write_node
+        prism_spot_constant_path_operator_write
+
+      when :def_node
+        case @point_type
+        when :name
+          prism_spot_def_for_name
+        when :args
+          raise NotImplementedError
+        end
+
+      when :lambda_node
+        case @point_type
+        when :name
+          prism_spot_lambda_for_name
+        when :args
+          raise NotImplementedError
+        end
+
+      when :block_node
+        case @point_type
+        when :name
+          prism_spot_block_for_name
+        when :args
+          raise NotImplementedError
+        end
+
+      end
+
+      if @snippet && @beg_column && @end_column && @beg_column < @end_column
+        return {
+          first_lineno: @beg_lineno,
+          first_column: @beg_column,
+          last_lineno: @end_lineno,
+          last_column: @end_column,
+          snippet: @snippet,
+          script_lines: @node.script_lines,
+        }
+      else
+        return nil
+      end
+
+    rescue NonAscii
+      nil
+    end
+
+    private
+
+    # Example:
+    #   x.foo
+    #    ^^^^
+    #   x.foo(42)
+    #    ^^^^
+    #   x&.foo
+    #    ^^^^^
+    #   x[42]
+    #    ^^^^
+    #   x += 1
+    #     ^
+    def spot_call_for_name
+      nd_recv, mid, nd_args = @node.children
+      lineno = nd_recv.last_lineno
+      lines = @fetch[lineno, @node.last_lineno]
+      if mid == :[] && lines.match(/\G[\s)]*(\[(?:\s*\])?)/, nd_recv.last_column)
+        @beg_column = $~.begin(1)
+        @snippet = lines[/.*\n/]
+        @beg_lineno = @end_lineno = lineno
+        if nd_args
+          if nd_recv.last_lineno == nd_args.last_lineno && @snippet.match(/\s*\]/, nd_args.last_column)
+            @end_column = $~.end(0)
+          end
+        else
+          if lines.match(/\G[\s)]*?\[\s*\]/, nd_recv.last_column)
+            @end_column = $~.end(0)
+          end
+        end
+      elsif lines.match(/\G[\s)]*?(\&?\.)(\s*?)(#{ Regexp.quote(mid) }).*\n/, nd_recv.last_column)
+        lines = $` + $&
+        @beg_column = $~.begin($2.include?("\n") ? 3 : 1)
+        @end_column = $~.end(3)
+        if i = lines[..@beg_column].rindex("\n")
+          @beg_lineno = @end_lineno = lineno + lines[..@beg_column].count("\n")
+          @snippet = lines[i + 1..]
+          @beg_column -= i + 1
+          @end_column -= i + 1
+        else
+          @snippet = lines
+          @beg_lineno = @end_lineno = lineno
+        end
+      elsif mid.to_s =~ /\A\W+\z/ && lines.match(/\G\s*(#{ Regexp.quote(mid) })=.*\n/, nd_recv.last_column)
+        @snippet = $` + $&
+        @beg_lineno = @end_lineno = lineno
+        @beg_column = $~.begin(1)
+        @end_column = $~.end(1)
+      end
+    end
+
+    # Example:
+    #   x.foo(42)
+    #         ^^
+    #   x[42]
+    #     ^^
+    #   x += 1
+    #        ^
+    def spot_call_for_args
+      _nd_recv, _mid, nd_args = @node.children
+      if nd_args && nd_args.first_lineno == nd_args.last_lineno
+        fetch_line(nd_args.first_lineno)
+        @beg_column = nd_args.first_column
+        @end_column = nd_args.last_column
+      end
+      # TODO: support @arg
+    end
+
+    # Example:
+    #   x.foo = 1
+    #    ^^^^^^
+    #   x[42] = 1
+    #    ^^^^^^
+    def spot_attrasgn_for_name
+      nd_recv, mid, nd_args = @node.children
+      *nd_args, _nd_last_arg, _nil = nd_args.children
+      fetch_line(nd_recv.last_lineno)
+      if mid == :[]= && @snippet.match(/\G[\s)]*(\[)/, nd_recv.last_column)
+        @beg_column = $~.begin(1)
+        args_last_column = $~.end(0)
+        if nd_args.last && nd_recv.last_lineno == nd_args.last.last_lineno
+          args_last_column = nd_args.last.last_column
+        end
+        if @snippet.match(/[\s)]*\]\s*=/, args_last_column)
+          @end_column = $~.end(0)
+        end
+      elsif @snippet.match(/\G[\s)]*(\.\s*#{ Regexp.quote(mid.to_s.sub(/=\z/, "")) }\s*=)/, nd_recv.last_column)
+        @beg_column = $~.begin(1)
+        @end_column = $~.end(1)
+      end
+    end
+
+    # Example:
+    #   x.foo = 1
+    #           ^
+    #   x[42] = 1
+    #     ^^^^^^^
+    #   x[] = 1
+    #     ^^^^^
+    def spot_attrasgn_for_args
+      nd_recv, mid, nd_args = @node.children
+      fetch_line(nd_recv.last_lineno)
+      if mid == :[]= && @snippet.match(/\G[\s)]*\[/, nd_recv.last_column)
+        @beg_column = $~.end(0)
+        if nd_recv.last_lineno == nd_args.last_lineno
+          @end_column = nd_args.last_column
+        end
+      elsif nd_args && nd_args.first_lineno == nd_args.last_lineno
+        @beg_column = nd_args.first_column
+        @end_column = nd_args.last_column
+      end
+      # TODO: support @arg
+    end
+
+    # Example:
+    #   x + 1
+    #     ^
+    #   +x
+    #   ^
+    def spot_opcall_for_name
+      nd_recv, op, nd_arg = @node.children
+      fetch_line(nd_recv.last_lineno)
+      if nd_arg
+        # binary operator
+        if @snippet.match(/\G[\s)]*(#{ Regexp.quote(op) })/, nd_recv.last_column)
+          @beg_column = $~.begin(1)
+          @end_column = $~.end(1)
+        end
+      else
+        # unary operator
+        if @snippet[...nd_recv.first_column].match(/(#{ Regexp.quote(op.to_s.sub(/@\z/, "")) })\s*\(?\s*\z/)
+          @beg_column = $~.begin(1)
+          @end_column = $~.end(1)
+        end
+      end
+    end
+
+    # Example:
+    #   x + 1
+    #       ^
+    def spot_opcall_for_args
+      _nd_recv, _op, nd_arg = @node.children
+      if nd_arg && nd_arg.first_lineno == nd_arg.last_lineno
+        # binary operator
+        fetch_line(nd_arg.first_lineno)
+        @beg_column = nd_arg.first_column
+        @end_column = nd_arg.last_column
+      end
+    end
+
+    # Example:
+    #   foo(42)
+    #   ^^^
+    #   foo 42
+    #   ^^^
+    def spot_fcall_for_name
+      mid, _nd_args = @node.children
+      fetch_line(@node.first_lineno)
+      if @snippet.match(/(#{ Regexp.quote(mid) })/, @node.first_column)
+        @beg_column = $~.begin(1)
+        @end_column = $~.end(1)
+      end
+    end
+
+    # Example:
+    #   foo(42)
+    #       ^^
+    #   foo 42
+    #       ^^
+    def spot_fcall_for_args
+      _mid, nd_args = @node.children
+      if nd_args && nd_args.first_lineno == nd_args.last_lineno
+        fetch_line(nd_args.first_lineno)
+        @beg_column = nd_args.first_column
+        @end_column = nd_args.last_column
+      end
+    end
+
+    # Example:
+    #   foo
+    #   ^^^
+    def spot_vcall
+      if @node.first_lineno == @node.last_lineno
+        fetch_line(@node.last_lineno)
+        @beg_column = @node.first_column
+        @end_column = @node.last_column
+      end
+    end
+
+    # Example:
+    #   x[1] += 42
+    #    ^^^    (for [])
+    #   x[1] += 42
+    #        ^  (for +)
+    #   x[1] += 42
+    #    ^^^^^^ (for []=)
+    def spot_op_asgn1_for_name
+      nd_recv, op, nd_args, _nd_rhs = @node.children
+      fetch_line(nd_recv.last_lineno)
+      if @snippet.match(/\G[\s)]*(\[)/, nd_recv.last_column)
+        bracket_beg_column = $~.begin(1)
+        args_last_column = $~.end(0)
+        if nd_args && nd_recv.last_lineno == nd_args.last_lineno
+          args_last_column = nd_args.last_column
+        end
+        if @snippet.match(/\s*\](\s*)(#{ Regexp.quote(op) })=()/, args_last_column)
+          case @name
+          when :[], :[]=
+            @beg_column = bracket_beg_column
+            @end_column = $~.begin(@name == :[] ? 1 : 3)
+          when op
+            @beg_column = $~.begin(2)
+            @end_column = $~.end(2)
+          end
+        end
+      end
+    end
+
+    # Example:
+    #   x[1] += 42
+    #     ^^^^^^^^
+    def spot_op_asgn1_for_args
+      nd_recv, mid, nd_args, nd_rhs = @node.children
+      fetch_line(nd_recv.last_lineno)
+      if mid == :[]= && @snippet.match(/\G\s*\[/, nd_recv.last_column)
+        @beg_column = $~.end(0)
+        if nd_recv.last_lineno == nd_rhs.last_lineno
+          @end_column = nd_rhs.last_column
+        end
+      elsif nd_args && nd_args.first_lineno == nd_rhs.last_lineno
+        @beg_column = nd_args.first_column
+        @end_column = nd_rhs.last_column
+      end
+      # TODO: support @arg
+    end
+
+    # Example:
+    #   x.foo += 42
+    #    ^^^     (for foo)
+    #   x.foo += 42
+    #         ^  (for +)
+    #   x.foo += 42
+    #    ^^^^^^^ (for foo=)
+    def spot_op_asgn2_for_name
+      nd_recv, _qcall, attr, op, _nd_rhs = @node.children
+      fetch_line(nd_recv.last_lineno)
+      if @snippet.match(/\G[\s)]*(\.)\s*#{ Regexp.quote(attr) }()\s*(#{ Regexp.quote(op) })(=)/, nd_recv.last_column)
+        case @name
+        when attr
+          @beg_column = $~.begin(1)
+          @end_column = $~.begin(2)
+        when op
+          @beg_column = $~.begin(3)
+          @end_column = $~.end(3)
+        when :"#{ attr }="
+          @beg_column = $~.begin(1)
+          @end_column = $~.end(4)
+        end
+      end
+    end
+
+    # Example:
+    #   x.foo += 42
+    #            ^^
+    def spot_op_asgn2_for_args
+      _nd_recv, _qcall, _attr, _op, nd_rhs = @node.children
+      if nd_rhs.first_lineno == nd_rhs.last_lineno
+        fetch_line(nd_rhs.first_lineno)
+        @beg_column = nd_rhs.first_column
+        @end_column = nd_rhs.last_column
+      end
+    end
+
+    # Example:
+    #   Foo::Bar
+    #      ^^^^^
+    def spot_colon2
+      nd_parent, const = @node.children
+      if nd_parent.last_lineno == @node.last_lineno
+        fetch_line(nd_parent.last_lineno)
+        @beg_column = nd_parent.last_column
+        @end_column = @node.last_column
+      else
+        fetch_line(@node.last_lineno)
+        if @snippet[...@node.last_column].match(/#{ Regexp.quote(const) }\z/)
+          @beg_lineno = @end_lineno = @node.last_lineno
+          @beg_column = $~.begin(0)
+          @end_column = $~.end(0)
+        end
+      end
+    end
+
+    # Example:
+    #   Foo::Bar += 1
+    #      ^^^^^^^^
+    def spot_op_cdecl
+      nd_lhs, op, _nd_rhs = @node.children
+      *nd_parent_lhs, _const = nd_lhs.children
+      if @name == op
+        fetch_line(nd_lhs.last_lineno)
+        if @snippet.match(/\G\s*(#{ Regexp.quote(op) })=/, nd_lhs.last_column)
+          @beg_column = $~.begin(1)
+          @end_column = $~.end(1)
+        end
+      else
+        # constant access error
+        @end_column = nd_lhs.last_column
+        if nd_parent_lhs.empty? # example: ::C += 1
+          if nd_lhs.first_lineno == nd_lhs.last_lineno
+            fetch_line(nd_lhs.last_lineno)
+            @beg_column = nd_lhs.first_column
+          end
+        else # example: Foo::Bar::C += 1
+          if nd_parent_lhs.last.last_lineno == nd_lhs.last_lineno
+            fetch_line(nd_lhs.last_lineno)
+            @beg_column = nd_parent_lhs.last.last_column
+          end
+        end
+      end
+    end
+
+    # Example:
+    #   def bar; end
+    #       ^^^
+    def spot_defn
+      mid, = @node.children
+      fetch_line(@node.first_lineno)
+      if @snippet.match(/\Gdef\s+(#{ Regexp.quote(mid) }\b)/, @node.first_column)
+        @beg_column = $~.begin(1)
+        @end_column = $~.end(1)
+      end
+    end
+
+    # Example:
+    #   def Foo.bar; end
+    #          ^^^^
+    def spot_defs
+      nd_recv, mid, = @node.children
+      fetch_line(nd_recv.last_lineno)
+      if @snippet.match(/\G\s*(\.\s*#{ Regexp.quote(mid) }\b)/, nd_recv.last_column)
+        @beg_column = $~.begin(1)
+        @end_column = $~.end(1)
+      end
+    end
+
+    # Example:
+    #   -> { ... }
+    #   ^^
+    def spot_lambda
+      fetch_line(@node.first_lineno)
+      if @snippet.match(/\G->/, @node.first_column)
+        @beg_column = $~.begin(0)
+        @end_column = $~.end(0)
+      end
+    end
+
+    # Example:
+    #   lambda { ... }
+    #          ^
+    #   define_method :foo do
+    #                      ^^
+    def spot_iter
+      _nd_fcall, nd_scope = @node.children
+      fetch_line(nd_scope.first_lineno)
+      if @snippet.match(/\G(?:do\b|\{)/, nd_scope.first_column)
+        @beg_column = $~.begin(0)
+        @end_column = $~.end(0)
+      end
+    end
+
+    def fetch_line(lineno)
+      @beg_lineno = @end_lineno = lineno
+      @snippet = @fetch[lineno]
+    end
+
+    # Take a location from the prism parser and set the necessary instance
+    # variables.
+    def prism_location(location)
+      @beg_lineno = location.start_line
+      @beg_column = location.start_column
+      @end_lineno = location.end_line
+      @end_column = location.end_column
+      @snippet = @fetch[@beg_lineno, @end_lineno]
+    end
+
+    # Example:
+    #   x.foo
+    #    ^^^^
+    #   x.foo(42)
+    #    ^^^^
+    #   x&.foo
+    #    ^^^^^
+    #   x[42]
+    #    ^^^^
+    #   x.foo = 1
+    #    ^^^^^^
+    #   x[42] = 1
+    #    ^^^^^^
+    #   x + 1
+    #     ^
+    #   +x
+    #   ^
+    #   foo(42)
+    #   ^^^
+    #   foo 42
+    #   ^^^
+    #   foo
+    #   ^^^
+    def prism_spot_call_for_name
+      # Explicitly turn off foo.() syntax because error_highlight expects this
+      # to not work.
+      return nil if @node.name == :call && @node.message_loc.nil?
+
+      location = @node.message_loc || @node.call_operator_loc || @node.location
+      location = @node.call_operator_loc.join(location) if @node.call_operator_loc&.start_line == location.start_line
+
+      # If the method name ends with "=" but the message does not, then this is
+      # a method call using the "attribute assignment" syntax
+      # (e.g., foo.bar = 1). In this case we need to go retrieve the = sign and
+      # add it to the location.
+      if (name = @node.name).end_with?("=") && !@node.message.end_with?("=")
+        location = location.adjoin("=")
+      end
+
+      prism_location(location)
+
+      if !name.end_with?("=") && !name.match?(/[[:alpha:]_\[]/)
+        # If the method name is an operator, then error_highlight only
+        # highlights the first line.
+        fetch_line(location.start_line)
+      end
+    end
+
+    # Example:
+    #   x.foo(42)
+    #         ^^
+    #   x[42]
+    #     ^^
+    #   x.foo = 1
+    #           ^
+    #   x[42] = 1
+    #     ^^^^^^^
+    #   x[] = 1
+    #     ^^^^^
+    #   x + 1
+    #       ^
+    #   foo(42)
+    #       ^^
+    #   foo 42
+    #       ^^
+    def prism_spot_call_for_args
+      # Disallow highlighting arguments if there are no arguments.
+      return if @node.arguments.nil?
+
+      # Explicitly turn off foo.() syntax because error_highlight expects this
+      # to not work.
+      return nil if @node.name == :call && @node.message_loc.nil?
+
+      if @node.name == :[]= && @node.opening == "[" && (@node.arguments&.arguments || []).length == 1
+        prism_location(@node.opening_loc.copy(start_offset: @node.opening_loc.start_offset + 1).join(@node.arguments.location))
+      else
+        prism_location(@node.arguments.location)
+      end
+    end
+
+    # Example:
+    #   x += 1
+    #     ^
+    def prism_spot_local_variable_operator_write_for_name
+      prism_location(@node.binary_operator_loc.chop)
+    end
+
+    # Example:
+    #   x += 1
+    #        ^
+    def prism_spot_local_variable_operator_write_for_args
+      prism_location(@node.value.location)
+    end
+
+    # Example:
+    #   x.foo += 42
+    #    ^^^     (for foo)
+    #   x.foo += 42
+    #         ^  (for +)
+    #   x.foo += 42
+    #    ^^^^^^^ (for foo=)
+    def prism_spot_call_operator_write_for_name
+      if !@name.start_with?(/[[:alpha:]_]/)
+        prism_location(@node.binary_operator_loc.chop)
+      else
+        location = @node.message_loc
+        if @node.call_operator_loc.start_line == location.start_line
+          location = @node.call_operator_loc.join(location)
+        end
+
+        location = location.adjoin("=") if @name.end_with?("=")
+        prism_location(location)
+      end
+    end
+
+    # Example:
+    #   x.foo += 42
+    #            ^^
+    def prism_spot_call_operator_write_for_args
+      prism_location(@node.value.location)
+    end
+
+    # Example:
+    #   x[1] += 42
+    #    ^^^    (for [])
+    #   x[1] += 42
+    #        ^  (for +)
+    #   x[1] += 42
+    #    ^^^^^^ (for []=)
+    def prism_spot_index_operator_write_for_name
+      case @name
+      when :[]
+        prism_location(@node.opening_loc.join(@node.closing_loc))
+      when :[]=
+        prism_location(@node.opening_loc.join(@node.closing_loc).adjoin("="))
+      else
+        # Explicitly turn off foo[] += 1 syntax when the operator is not on
+        # the same line because error_highlight expects this to not work.
+        return nil if @node.binary_operator_loc.start_line != @node.opening_loc.start_line
+
+        prism_location(@node.binary_operator_loc.chop)
+      end
+    end
+
+    # Example:
+    #   x[1] += 42
+    #     ^^^^^^^^
+    def prism_spot_index_operator_write_for_args
+      opening_loc =
+        if @node.arguments.nil?
+          @node.opening_loc.copy(start_offset: @node.opening_loc.start_offset + 1)
+        else
+          @node.arguments.location
+        end
+
+      prism_location(opening_loc.join(@node.value.location))
+    end
+
+    # Example:
+    #   Foo
+    #   ^^^
+    def prism_spot_constant_read
+      prism_location(@node.location)
+    end
+
+    # Example:
+    #   Foo::Bar
+    #      ^^^^^
+    def prism_spot_constant_path
+      if @node.parent && @node.parent.location.end_line == @node.location.end_line
+        fetch_line(@node.parent.location.end_line)
+        prism_location(@node.delimiter_loc.join(@node.name_loc))
+      else
+        fetch_line(@node.location.end_line)
+        location = @node.name_loc
+        location = @node.delimiter_loc.join(location) if @node.delimiter_loc.end_line == location.start_line
+        prism_location(location)
+      end
+    end
+
+    # Example:
+    #   Foo::Bar += 1
+    #      ^^^^^^^^
+    def prism_spot_constant_path_operator_write
+      if @name == (target = @node.target).name
+        prism_location(target.delimiter_loc.join(target.name_loc))
+      else
+        prism_location(@node.binary_operator_loc.chop)
+      end
+    end
+
+    # Example:
+    #   def foo()
+    #       ^^^
+    def prism_spot_def_for_name
+      location = @node.name_loc
+      location = @node.operator_loc.join(location) if @node.operator_loc
+      prism_location(location)
+    end
+
+    # Example:
+    #   -> x, y { }
+    #   ^^
+    def prism_spot_lambda_for_name
+      prism_location(@node.operator_loc)
+    end
+
+    # Example:
+    #   lambda { }
+    #          ^
+    #   define_method :foo do |x, y|
+    #                      ^
+    def prism_spot_block_for_name
+      prism_location(@node.opening_loc)
+    end
+  end
+
+  private_constant :Spotter
+end
diff --git a/lib/error_highlight/core_ext.rb b/lib/error_highlight/core_ext.rb
new file mode 100644
index 0000000000..c3354f46cd
--- /dev/null
+++ b/lib/error_highlight/core_ext.rb
@@ -0,0 +1,76 @@
+require_relative "formatter"
+
+module ErrorHighlight
+  module CoreExt
+    private def generate_snippet
+      if ArgumentError === self && message =~ /\A(?:wrong number of arguments|missing keyword[s]?|unknown keyword[s]?|no keywords accepted)\b/
+        locs = self.backtrace_locations
+        return "" if locs.size < 2
+        callee_loc, caller_loc = locs
+        callee_spot = ErrorHighlight.spot(self, backtrace_location: callee_loc, point_type: :name)
+        caller_spot = ErrorHighlight.spot(self, backtrace_location: caller_loc, point_type: :name)
+        if caller_spot && callee_spot &&
+            caller_loc.path == callee_loc.path &&
+            caller_loc.lineno == callee_loc.lineno &&
+            caller_spot == callee_spot
+          callee_loc = callee_spot = nil
+        end
+        ret = +"\n"
+        [["caller", caller_loc, caller_spot], ["callee", callee_loc, callee_spot]].each do |header, loc, spot|
+          out = nil
+          if loc
+            out = "    #{ header }: #{ loc.path }:#{ loc.lineno }"
+            if spot
+              _, _, snippet, highlight = ErrorHighlight.formatter.message_for(spot).lines
+              out += "\n    | #{ snippet }      #{ highlight }"
+            else
+              # do nothing
+            end
+          end
+          ret << "\n" + out if out
+        end
+        ret
+      else
+        spot = ErrorHighlight.spot(self)
+        return "" unless spot
+        return ErrorHighlight.formatter.message_for(spot)
+      end
+    end
+
+    if Exception.method_defined?(:detailed_message)
+      def detailed_message(highlight: false, error_highlight: true, **)
+        return super unless error_highlight
+        snippet = generate_snippet
+        if highlight
+          snippet = snippet.gsub(/.+/) { "\e[1m" + $& + "\e[m" }
+        end
+        super + snippet
+      end
+    else
+      # This is a marker to let `DidYouMean::Correctable#original_message` skip
+      # the following method definition of `to_s`.
+      # See https://github.com/ruby/did_you_mean/pull/152
+      SKIP_TO_S_FOR_SUPER_LOOKUP = true
+      private_constant :SKIP_TO_S_FOR_SUPER_LOOKUP
+
+      def to_s
+        msg = super
+        snippet = generate_snippet
+        if snippet != "" && !msg.include?(snippet)
+          msg + snippet
+        else
+          msg
+        end
+      end
+    end
+  end
+
+  NameError.prepend(CoreExt)
+
+  if Exception.method_defined?(:detailed_message)
+    # ErrorHighlight is enabled for TypeError and ArgumentError only when Exception#detailed_message is available.
+    # This is because changing ArgumentError#message is highly incompatible.
+    TypeError.prepend(CoreExt)
+    ArgumentError.prepend(CoreExt)
+  end
+end
diff --git a/lib/error_highlight/error_highlight.gemspec b/lib/error_highlight/error_highlight.gemspec
new file mode 100644
index 0000000000..edfc4b776f
--- /dev/null
+++ b/lib/error_highlight/error_highlight.gemspec
@@ -0,0 +1,27 @@
+# coding: utf-8
+lib = File.expand_path('../lib', __FILE__)
+$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
+begin
+  require_relative "lib/error_highlight/version"
+rescue LoadError # Fallback to load version file in ruby core repository
+  require_relative "version"
+end
+
+Gem::Specification.new do |spec|
+  spec.name          = "error_highlight"
+  spec.version       = ErrorHighlight::VERSION
+  spec.authors       = ["Yusuke Endoh"]
+  spec.email         = ["mame@ruby-lang.org"]
+
+  spec.summary       = 'Shows a one-line code snippet with an underline in the error backtrace'
+  spec.description   = 'The gem enhances Exception#message by adding a short explanation where the exception is raised'
+  spec.homepage      = "https://github.com/ruby/error_highlight"
+
+  spec.license       = "MIT"
+  spec.required_ruby_version = Gem::Requirement.new(">= 3.2.0")
+
+  spec.files = Dir.chdir(File.expand_path(__dir__)) do
+    `git ls-files -z`.split("\x0").reject { |f| f.match(%r{\A(?:test|spec|features)/}) }
+  end
+  spec.require_paths = ["lib"]
+end
diff --git a/lib/error_highlight/formatter.rb b/lib/error_highlight/formatter.rb
new file mode 100644
index 0000000000..d2fad9e75c
--- /dev/null
+++ b/lib/error_highlight/formatter.rb
@@ -0,0 +1,74 @@
+module ErrorHighlight
+  class DefaultFormatter
+    MIN_SNIPPET_WIDTH = 20
+
+    def self.message_for(spot)
+      # currently only a one-line code snippet is supported
+      return "" unless spot[:first_lineno] == spot[:last_lineno]
+
+      snippet      = spot[:snippet]
+      first_column = spot[:first_column]
+      last_column  = spot[:last_column]
+      ellipsis     = "..."
+
+      # truncate snippet to fit in the viewport
+      if max_snippet_width && snippet.size > max_snippet_width
+        available_width = max_snippet_width - ellipsis.size
+        center          = first_column - max_snippet_width / 2
+
+        visible_start  = last_column < available_width ? 0 : [center, 0].max
+        visible_end    = visible_start + max_snippet_width
+        visible_start  = snippet.size - max_snippet_width if visible_end > snippet.size
+
+        prefix = visible_start.positive?    ? ellipsis : ""
+        suffix = visible_end < snippet.size ? ellipsis : ""
+
+        snippet = prefix + snippet[(visible_start + prefix.size)...(visible_end - suffix.size)] + suffix
+        snippet << "\n" unless snippet.end_with?("\n")
+
+        first_column -= visible_start
+        last_column  = [last_column - visible_start, snippet.size - 1].min
+      end
+
+      indent = snippet[0...first_column].gsub(/[^\t]/, " ")
+      marker = indent + "^" * (last_column - first_column)
+
+      "\n\n#{ snippet }#{ marker }"
+    end
+
+    def self.max_snippet_width
+      return if Ractor.current[:__error_highlight_max_snippet_width__] == :disabled
+
+      Ractor.current[:__error_highlight_max_snippet_width__] ||= terminal_width
+    end
+
+    def self.max_snippet_width=(width)
+      return Ractor.current[:__error_highlight_max_snippet_width__] = :disabled if width.nil?
+
+      width = width.to_i
+
+      if width < MIN_SNIPPET_WIDTH
+        warn "'max_snippet_width' adjusted to minimum value of #{MIN_SNIPPET_WIDTH}."
+        width = MIN_SNIPPET_WIDTH
+      end
+
+      Ractor.current[:__error_highlight_max_snippet_width__] = width
+    end
+
+    def self.terminal_width
+      # lazy load io/console to avoid loading it when 'max_snippet_width' is manually set
+      require "io/console"
+      $stderr.winsize[1] if $stderr.tty?
+    rescue LoadError, NoMethodError, SystemCallError
+      # skip truncation when terminal window size is unavailable
+    end
+  end
+
+  def self.formatter
+    Ractor.current[:__error_highlight_formatter__] || DefaultFormatter
+  end
+
+  def self.formatter=(formatter)
+    Ractor.current[:__error_highlight_formatter__] = formatter
+  end
+end
diff --git a/lib/error_highlight/version.rb b/lib/error_highlight/version.rb
new file mode 100644
index 0000000000..f0a5376b14
--- /dev/null
+++ b/lib/error_highlight/version.rb
@@ -0,0 +1,3 @@
+module ErrorHighlight
+  VERSION = "0.7.1"
+end
diff --git a/lib/fileutils.gemspec b/lib/fileutils.gemspec
new file mode 100644
index 0000000000..2603d664da
--- /dev/null
+++ b/lib/fileutils.gemspec
@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+source_version = ["", "lib/"].find do |dir|
+  begin
+    break File.open(File.join(__dir__, "#{dir}fileutils.rb")) {|f|
+      f.gets("\n  VERSION = ")
+      f.gets[/\s*"(.+)"/, 1]
+    }
+  rescue Errno::ENOENT
+  end
+end
+
+Gem::Specification.new do |s|
+  s.name = "fileutils"
+  s.version = source_version
+  s.summary = "Several file utility methods for copying, moving, removing, etc."
+  s.description = "Several file utility methods for copying, moving, removing, etc."
+
+  s.require_path = %w{lib}
+  s.files = ["COPYING", "BSDL", "README.md", "Rakefile", "fileutils.gemspec", "lib/fileutils.rb"]
+  s.required_ruby_version = ">= 2.5.0"
+
+  s.authors = ["Minero Aoki"]
+  s.email = [nil]
+  s.homepage = "https://github.com/ruby/fileutils"
+  s.licenses = ["Ruby", "BSD-2-Clause"]
+
+  s.metadata = {
+    "source_code_uri" => "https://github.com/ruby/fileutils"
+  }
+end
diff --git a/lib/fileutils.rb b/lib/fileutils.rb
index ee396e35cb..0706e007ca 100644
--- a/lib/fileutils.rb
+++ b/lib/fileutils.rb
@@ -1,101 +1,199 @@
+# frozen_string_literal: true
+
+begin
+  require 'rbconfig'
+rescue LoadError
+  # for make rjit-headers
+end
+
+# Namespace for file utility methods for copying, moving, removing, etc.
 #
-# = fileutils.rb
+# == What's Here
 #
-# Copyright (c) 2000-2007 Minero Aoki
+# First, what’s elsewhere. \Module \FileUtils:
 #
-# This program is free software.
-# You can distribute/modify this program under the same terms of ruby.
+# - Inherits from {class Object}[rdoc-ref:Object].
+# - Supplements {class File}[rdoc-ref:File]
+#   (but is not included or extended there).
 #
-# == module FileUtils
+# Here, module \FileUtils provides methods that are useful for:
 #
-# Namespace for several file utility methods for copying, moving, removing, etc.
+# - {Creating}[rdoc-ref:FileUtils@Creating].
+# - {Deleting}[rdoc-ref:FileUtils@Deleting].
+# - {Querying}[rdoc-ref:FileUtils@Querying].
+# - {Setting}[rdoc-ref:FileUtils@Setting].
+# - {Comparing}[rdoc-ref:FileUtils@Comparing].
+# - {Copying}[rdoc-ref:FileUtils@Copying].
+# - {Moving}[rdoc-ref:FileUtils@Moving].
+# - {Options}[rdoc-ref:FileUtils@Options].
 #
-# === Module Functions
+# === Creating
 #
-#   cd(dir, options)
-#   cd(dir, options) {|dir| .... }
-#   pwd()
-#   mkdir(dir, options)
-#   mkdir(list, options)
-#   mkdir_p(dir, options)
-#   mkdir_p(list, options)
-#   rmdir(dir, options)
-#   rmdir(list, options)
-#   ln(old, new, options)
-#   ln(list, destdir, options)
-#   ln_s(old, new, options)
-#   ln_s(list, destdir, options)
-#   ln_sf(src, dest, options)
-#   cp(src, dest, options)
-#   cp(list, dir, options)
-#   cp_r(src, dest, options)
-#   cp_r(list, dir, options)
-#   mv(src, dest, options)
-#   mv(list, dir, options)
-#   rm(list, options)
-#   rm_r(list, options)
-#   rm_rf(list, options)
-#   install(src, dest, mode = <src's>, options)
-#   chmod(mode, list, options)
-#   chmod_R(mode, list, options)
-#   chown(user, group, list, options)
-#   chown_R(user, group, list, options)
-#   touch(list, options)
+# - ::mkdir: Creates directories.
+# - ::mkdir_p, ::makedirs, ::mkpath: Creates directories,
+#   also creating ancestor directories as needed.
+# - ::link_entry: Creates a hard link.
+# - ::ln, ::link: Creates hard links.
+# - ::ln_s, ::symlink: Creates symbolic links.
+# - ::ln_sf: Creates symbolic links, overwriting if necessary.
+# - ::ln_sr: Creates symbolic links relative to targets
 #
-# The <tt>options</tt> parameter is a hash of options, taken from the list
-# <tt>:force</tt>, <tt>:noop</tt>, <tt>:preserve</tt>, and <tt>:verbose</tt>.
-# <tt>:noop</tt> means that no changes are made.  The other two are obvious.
-# Each method documents the options that it honours.
+# === Deleting
 #
-# All methods that have the concept of a "source" file or directory can take
-# either one file or a list of files in that argument.  See the method
-# documentation for examples.
+# - ::remove_dir: Removes a directory and its descendants.
+# - ::remove_entry: Removes an entry, including its descendants if it is a directory.
+# - ::remove_entry_secure: Like ::remove_entry, but removes securely.
+# - ::remove_file: Removes a file entry.
+# - ::rm, ::remove: Removes entries.
+# - ::rm_f, ::safe_unlink: Like ::rm, but removes forcibly.
+# - ::rm_r: Removes entries and their descendants.
+# - ::rm_rf, ::rmtree: Like ::rm_r, but removes forcibly.
+# - ::rmdir: Removes directories.
 #
-# There are some `low level' methods, which do not accept any option:
+# === Querying
 #
-#   copy_entry(src, dest, preserve = false, dereference = false)
-#   copy_file(src, dest, preserve = false, dereference = true)
-#   copy_stream(srcstream, deststream)
-#   remove_entry(path, force = false)
-#   remove_entry_secure(path, force = false)
-#   remove_file(path, force = false)
-#   compare_file(path_a, path_b)
-#   compare_stream(stream_a, stream_b)
-#   uptodate?(file, cmp_list)
+# - ::pwd, ::getwd: Returns the path to the working directory.
+# - ::uptodate?: Returns whether a given entry is newer than given other entries.
 #
-# == module FileUtils::Verbose
+# === Setting
 #
-# This module has all methods of FileUtils module, but it outputs messages
-# before acting.  This equates to passing the <tt>:verbose</tt> flag to methods
-# in FileUtils.
+# - ::cd, ::chdir: Sets the working directory.
+# - ::chmod: Sets permissions for an entry.
+# - ::chmod_R: Sets permissions for an entry and its descendants.
+# - ::chown: Sets the owner and group for entries.
+# - ::chown_R: Sets the owner and group for entries and their descendants.
+# - ::touch: Sets modification and access times for entries,
+#   creating if necessary.
 #
-# == module FileUtils::NoWrite
+# === Comparing
 #
-# This module has all methods of FileUtils module, but never changes
-# files/directories.  This equates to passing the <tt>:noop</tt> flag to methods
-# in FileUtils.
+# - ::compare_file, ::cmp, ::identical?: Returns whether two entries are identical.
+# - ::compare_stream: Returns whether two streams are identical.
 #
-# == module FileUtils::DryRun
+# === Copying
 #
-# This module has all methods of FileUtils module, but never changes
-# files/directories.  This equates to passing the <tt>:noop</tt> and
-# <tt>:verbose</tt> flags to methods in FileUtils.
+# - ::copy_entry: Recursively copies an entry.
+# - ::copy_file: Copies an entry.
+# - ::copy_stream: Copies a stream.
+# - ::cp, ::copy: Copies files.
+# - ::cp_lr: Recursively creates hard links.
+# - ::cp_r: Recursively copies files, retaining mode, owner, and group.
+# - ::install: Recursively copies files, optionally setting mode,
+#   owner, and group.
+#
+# === Moving
+#
+# - ::mv, ::move: Moves entries.
+#
+# === Options
+#
+# - ::collect_method: Returns the names of methods that accept a given option.
+# - ::commands: Returns the names of methods that accept options.
+# - ::have_option?: Returns whether a given method accepts a given option.
+# - ::options: Returns all option names.
+# - ::options_of: Returns the names of the options for a given method.
+#
+# == Path Arguments
+#
+# Some methods in \FileUtils accept _path_ arguments,
+# which are interpreted as paths to filesystem entries:
+#
+# - If the argument is a string, that value is the path.
+# - If the argument has method +:to_path+, it is converted via that method.
+# - If the argument has method +:to_str+, it is converted via that method.
+#
+# == About the Examples
+#
+# Some examples here involve trees of file entries.
+# For these, we sometimes display trees using the
+# {tree command-line utility}[https://en.wikipedia.org/wiki/Tree_(command)],
+# which is a recursive directory-listing utility that produces
+# a depth-indented listing of files and directories.
+#
+# We use a helper method to launch the command and control the format:
+#
+#   def tree(dirpath = '.')
+#     command = "tree --noreport --charset=ascii #{dirpath}"
+#     system(command)
+#   end
+#
+# To illustrate:
+#
+#   tree('src0')
+#   # => src0
+#   #    |-- sub0
+#   #    |   |-- src0.txt
+#   #    |   `-- src1.txt
+#   #    `-- sub1
+#   #        |-- src2.txt
+#   #        `-- src3.txt
+#
+# == Avoiding the TOCTTOU Vulnerability
+#
+# For certain methods that recursively remove entries,
+# there is a potential vulnerability called the
+# {Time-of-check to time-of-use}[https://en.wikipedia.org/wiki/Time-of-check_to_time-of-use],
+# or TOCTTOU, vulnerability that can exist when:
+#
+# - An ancestor directory of the entry at the target path is world writable;
+#   such directories include <tt>/tmp</tt>.
+# - The directory tree at the target path includes:
+#
+#   - A world-writable descendant directory.
+#   - A symbolic link.
+#
+# To avoid that vulnerability, you can use this method to remove entries:
+#
+# - FileUtils.remove_entry_secure: removes recursively
+#   if the target path points to a directory.
+#
+# Also available are these methods,
+# each of which calls \FileUtils.remove_entry_secure:
+#
+# - FileUtils.rm_r with keyword argument <tt>secure: true</tt>.
+# - FileUtils.rm_rf with keyword argument <tt>secure: true</tt>.
+#
+# Finally, this method for moving entries calls \FileUtils.remove_entry_secure
+# if the source and destination are on different file systems
+# (which means that the "move" is really a copy and remove):
+#
+# - FileUtils.mv with keyword argument <tt>secure: true</tt>.
+#
+# \Method \FileUtils.remove_entry_secure removes securely
+# by applying a special pre-process:
+#
+# - If the target path points to a directory, this method uses methods
+#   {File#chown}[rdoc-ref:File#chown]
+#   and {File#chmod}[rdoc-ref:File#chmod]
+#   in removing directories.
+# - The owner of the target directory should be either the current process
+#   or the super user (root).
+#
+# WARNING: You must ensure that *ALL* parent directories cannot be
+# moved by other untrusted users.  For example, parent directories
+# should not be owned by untrusted users, and should not be world
+# writable except when the sticky bit is set.
+#
+# For details of this security vulnerability, see Perl cases:
+#
+# - {CVE-2005-0448}[https://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-0448].
+# - {CVE-2004-0452}[https://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2004-0452].
 #
-
 module FileUtils
+  # The version number.
+  VERSION = "1.8.0"
 
   def self.private_module_function(name)   #:nodoc:
     module_function name
     private_class_method name
   end
 
-  # This hash table holds command options.
-  OPT_TABLE = {}   #:nodoc: internal use only
-
   #
-  # Options: (none)
+  # Returns a string containing the path to the current directory:
+  #
+  #   FileUtils.pwd # => "/rdoc/fileutils"
   #
-  # Returns the name of the current directory.
+  # Related: FileUtils.cd.
   #
   def pwd
     Dir.pwd
@@ -105,46 +203,66 @@ module FileUtils
   alias getwd pwd
   module_function :getwd
 
+  # Changes the working directory to the given +dir+, which
+  # should be {interpretable as a path}[rdoc-ref:FileUtils@Path+Arguments]:
+  #
+  # With no block given,
+  # changes the current directory to the directory at +dir+; returns zero:
   #
-  # Options: verbose
+  #   FileUtils.pwd # => "/rdoc/fileutils"
+  #   FileUtils.cd('..')
+  #   FileUtils.pwd # => "/rdoc"
+  #   FileUtils.cd('fileutils')
   #
-  # Changes the current directory to the directory +dir+.
+  # With a block given, changes the current directory to the directory
+  # at +dir+, calls the block with argument +dir+,
+  # and restores the original current directory; returns the block's value:
   #
-  # If this method is called with block, resumes to the old
-  # working directory after the block execution finished.
+  #   FileUtils.pwd                                     # => "/rdoc/fileutils"
+  #   FileUtils.cd('..') { |arg| [arg, FileUtils.pwd] } # => ["..", "/rdoc"]
+  #   FileUtils.pwd                                     # => "/rdoc/fileutils"
   #
-  #   FileUtils.cd('/', :verbose => true)   # chdir and report it
+  # Keyword arguments:
   #
-  #   FileUtils.cd('/') do  # chdir
-  #     [...]               # do something
-  #   end                   # return to original directory
-  #   
-  def cd(dir, options = {}, &block) # :yield: dir
-    fu_check_options options, OPT_TABLE['cd']
-    fu_output_message "cd #{dir}" if options[:verbose]
-    Dir.chdir(dir, &block)
-    fu_output_message 'cd -' if options[:verbose] and block
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     FileUtils.cd('..')
+  #     FileUtils.cd('fileutils')
+  #
+  #   Output:
+  #
+  #     cd ..
+  #     cd fileutils
+  #
+  # Related: FileUtils.pwd.
+  #
+  def cd(dir, verbose: nil, &block) # :yield: dir
+    fu_output_message "cd #{dir}" if verbose
+    result = Dir.chdir(dir, &block)
+    fu_output_message 'cd -' if verbose and block
+    result
   end
   module_function :cd
 
   alias chdir cd
   module_function :chdir
 
-  OPT_TABLE['cd']    =
-  OPT_TABLE['chdir'] = [:verbose]
-
   #
-  # Options: (none)
+  # Returns +true+ if the file at path +new+
+  # is newer than all the files at paths in array +old_list+;
+  # +false+ otherwise.
   #
-  # Returns true if +newer+ is newer than all +old_list+.
-  # Non-existent files are older than any file.
+  # Argument +new+ and the elements of +old_list+
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments]:
   #
-  #   FileUtils.uptodate?('hello.o', %w(hello.c hello.h)) or \
-  #       system 'make hello.o'
+  #   FileUtils.uptodate?('Rakefile', ['Gemfile', 'README.md']) # => true
+  #   FileUtils.uptodate?('Gemfile', ['Rakefile', 'README.md']) # => false
   #
-  def uptodate?(new, old_list, options = nil)
-    raise ArgumentError, 'uptodate? does not accept any option' if options
-
+  # A non-existent file is considered to be infinitely old.
+  #
+  # Related: FileUtils.touch.
+  #
+  def uptodate?(new, old_list)
     return false unless File.exist?(new)
     new_time = File.mtime(new)
     old_list.each do |old|
@@ -156,69 +274,111 @@ module FileUtils
   end
   module_function :uptodate?
 
+  def remove_trailing_slash(dir)   #:nodoc:
+    dir == '/' ? dir : dir.chomp(?/)
+  end
+  private_module_function :remove_trailing_slash
+
   #
-  # Options: mode noop verbose
+  # Creates directories at the paths in the given +list+
+  # (a single path or an array of paths);
+  # returns +list+ if it is an array, <tt>[list]</tt> otherwise.
   #
-  # Creates one or more directories.
+  # Argument +list+ or its elements
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
   #
-  #   FileUtils.mkdir 'test'
-  #   FileUtils.mkdir %w( tmp data )
-  #   FileUtils.mkdir 'notexist', :noop => true  # Does not really create.
-  #   FileUtils.mkdir 'tmp', :mode => 0700
+  # With no keyword arguments, creates a directory at each +path+ in +list+
+  # by calling: <tt>Dir.mkdir(path, mode)</tt>;
+  # see {Dir.mkdir}[rdoc-ref:Dir.mkdir]:
   #
-  def mkdir(list, options = {})
-    fu_check_options options, OPT_TABLE['mkdir']
+  #   FileUtils.mkdir(%w[tmp0 tmp1]) # => ["tmp0", "tmp1"]
+  #   FileUtils.mkdir('tmp4')        # => ["tmp4"]
+  #
+  # Keyword arguments:
+  #
+  # - <tt>mode: <i>mode</i></tt> - also calls <tt>File.chmod(mode, path)</tt>;
+  #   see {File.chmod}[rdoc-ref:File.chmod].
+  # - <tt>noop: true</tt> - does not create directories.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     FileUtils.mkdir(%w[tmp0 tmp1], verbose: true)
+  #     FileUtils.mkdir(%w[tmp2 tmp3], mode: 0700, verbose: true)
+  #
+  #   Output:
+  #
+  #     mkdir tmp0 tmp1
+  #     mkdir -m 700 tmp2 tmp3
+  #
+  # Raises an exception if any path points to an existing
+  # file or directory, or if for any reason a directory cannot be created.
+  #
+  # Related: FileUtils.mkdir_p.
+  #
+  def mkdir(list, mode: nil, noop: nil, verbose: nil)
     list = fu_list(list)
-    fu_output_message "mkdir #{options[:mode] ? ('-m %03o ' % options[:mode]) : ''}#{list.join ' '}" if options[:verbose]
-    return if options[:noop]
+    fu_output_message "mkdir #{mode ? ('-m %03o ' % mode) : ''}#{list.join ' '}" if verbose
+    return if noop
 
     list.each do |dir|
-      fu_mkdir dir, options[:mode]
+      fu_mkdir dir, mode
     end
   end
   module_function :mkdir
 
-  OPT_TABLE['mkdir'] = [:mode, :noop, :verbose]
-
   #
-  # Options: mode noop verbose
+  # Creates directories at the paths in the given +list+
+  # (a single path or an array of paths),
+  # also creating ancestor directories as needed;
+  # returns +list+ if it is an array, <tt>[list]</tt> otherwise.
+  #
+  # Argument +list+ or its elements
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # With no keyword arguments, creates a directory at each +path+ in +list+,
+  # along with any needed ancestor directories,
+  # by calling: <tt>Dir.mkdir(path, mode)</tt>;
+  # see {Dir.mkdir}[rdoc-ref:Dir.mkdir]:
+  #
+  #   FileUtils.mkdir_p(%w[tmp0/tmp1 tmp2/tmp3]) # => ["tmp0/tmp1", "tmp2/tmp3"]
+  #   FileUtils.mkdir_p('tmp4/tmp5')             # => ["tmp4/tmp5"]
   #
-  # Creates a directory and all its parent directories.
-  # For example,
+  # Keyword arguments:
   #
-  #   FileUtils.mkdir_p '/usr/local/lib/ruby'
+  # - <tt>mode: <i>mode</i></tt> - also calls <tt>File.chmod(mode, path)</tt>;
+  #   see {File.chmod}[rdoc-ref:File.chmod].
+  # - <tt>noop: true</tt> - does not create directories.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
   #
-  # causes to make following directories, if it does not exist.
-  #     * /usr
-  #     * /usr/local
-  #     * /usr/local/lib
-  #     * /usr/local/lib/ruby
+  #     FileUtils.mkdir_p(%w[tmp0 tmp1], verbose: true)
+  #     FileUtils.mkdir_p(%w[tmp2 tmp3], mode: 0700, verbose: true)
   #
-  # You can pass several directories at a time in a list.
+  #   Output:
   #
-  def mkdir_p(list, options = {})
-    fu_check_options options, OPT_TABLE['mkdir_p']
+  #     mkdir -p tmp0 tmp1
+  #     mkdir -p -m 700 tmp2 tmp3
+  #
+  # Raises an exception if for any reason a directory cannot be created.
+  #
+  # FileUtils.mkpath and FileUtils.makedirs are aliases for FileUtils.mkdir_p.
+  #
+  # Related: FileUtils.mkdir.
+  #
+  def mkdir_p(list, mode: nil, noop: nil, verbose: nil)
     list = fu_list(list)
-    fu_output_message "mkdir -p #{options[:mode] ? ('-m %03o ' % options[:mode]) : ''}#{list.join ' '}" if options[:verbose]
-    return *list if options[:noop]
+    fu_output_message "mkdir -p #{mode ? ('-m %03o ' % mode) : ''}#{list.join ' '}" if verbose
+    return *list if noop
 
-    list.map {|path| path.chomp(?/) }.each do |path|
-      # optimize for the most common case
-      begin
-        fu_mkdir path, options[:mode]
-        next
-      rescue SystemCallError
-        next if File.directory?(path)
-      end
+    list.each do |item|
+      path = remove_trailing_slash(item)
 
       stack = []
-      until path == stack.last   # dirname("/")=="/", dirname("C:/")=="C:/"
+      until File.directory?(path) || File.dirname(path) == path
         stack.push path
         path = File.dirname(path)
       end
       stack.reverse_each do |dir|
         begin
-          fu_mkdir dir, options[:mode]
+          fu_mkdir dir, mode
         rescue SystemCallError
           raise unless File.directory?(dir)
         end
@@ -234,12 +394,8 @@ module FileUtils
   module_function :mkpath
   module_function :makedirs
 
-  OPT_TABLE['mkdir_p']  =
-  OPT_TABLE['mkpath']   =
-  OPT_TABLE['makedirs'] = [:mode, :noop, :verbose]
-
   def fu_mkdir(path, mode)   #:nodoc:
-    path = path.chomp(?/)
+    path = remove_trailing_slash(path)
     if mode
       Dir.mkdir path, mode
       File.chmod mode, path
@@ -250,65 +406,119 @@ module FileUtils
   private_module_function :fu_mkdir
 
   #
-  # Options: noop, verbose
+  # Removes directories at the paths in the given +list+
+  # (a single path or an array of paths);
+  # returns +list+, if it is an array, <tt>[list]</tt> otherwise.
+  #
+  # Argument +list+ or its elements
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # With no keyword arguments, removes the directory at each +path+ in +list+,
+  # by calling: <tt>Dir.rmdir(path)</tt>;
+  # see {Dir.rmdir}[rdoc-ref:Dir.rmdir]:
+  #
+  #   FileUtils.rmdir(%w[tmp0/tmp1 tmp2/tmp3]) # => ["tmp0/tmp1", "tmp2/tmp3"]
+  #   FileUtils.rmdir('tmp4/tmp5')             # => ["tmp4/tmp5"]
   #
-  # Removes one or more directories.
+  # Keyword arguments:
   #
-  #   FileUtils.rmdir 'somedir'
-  #   FileUtils.rmdir %w(somedir anydir otherdir)
-  #   # Does not really remove directory; outputs message.
-  #   FileUtils.rmdir 'somedir', :verbose => true, :noop => true
+  # - <tt>parents: true</tt> - removes successive ancestor directories
+  #   if empty.
+  # - <tt>noop: true</tt> - does not remove directories.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
   #
-  def rmdir(list, options = {})
-    fu_check_options options, OPT_TABLE['rmdir']
+  #     FileUtils.rmdir(%w[tmp0/tmp1 tmp2/tmp3], parents: true, verbose: true)
+  #     FileUtils.rmdir('tmp4/tmp5', parents: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     rmdir -p tmp0/tmp1 tmp2/tmp3
+  #     rmdir -p tmp4/tmp5
+  #
+  # Raises an exception if a directory does not exist
+  # or if for any reason a directory cannot be removed.
+  #
+  # Related: {methods for deleting}[rdoc-ref:FileUtils@Deleting].
+  #
+  def rmdir(list, parents: nil, noop: nil, verbose: nil)
     list = fu_list(list)
-    parents = options[:parents]
-    fu_output_message "rmdir #{parents ? '-p ' : ''}#{list.join ' '}" if options[:verbose]
-    return if options[:noop]
+    fu_output_message "rmdir #{parents ? '-p ' : ''}#{list.join ' '}" if verbose
+    return if noop
     list.each do |dir|
-      begin
-        Dir.rmdir(dir = dir.chomp(?/))
-        if parents
+      Dir.rmdir(dir = remove_trailing_slash(dir))
+      if parents
+        begin
           until (parent = File.dirname(dir)) == '.' or parent == dir
+            dir = parent
             Dir.rmdir(dir)
           end
+        rescue Errno::ENOTEMPTY, Errno::EEXIST, Errno::ENOENT
         end
-      rescue Errno::ENOTEMPTY, Errno::ENOENT
       end
     end
   end
   module_function :rmdir
 
-  OPT_TABLE['rmdir'] = [:parents, :noop, :verbose]
-
+  # Creates {hard links}[https://en.wikipedia.org/wiki/Hard_link].
+  #
+  # Arguments +src+ (a single path or an array of paths)
+  # and +dest+ (a single path)
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # When +src+ is the path to an existing file
+  # and +dest+ is the path to a non-existent file,
+  # creates a hard link at +dest+ pointing to +src+; returns zero:
+  #
+  #   Dir.children('tmp0/')                    # => ["t.txt"]
+  #   Dir.children('tmp1/')                    # => []
+  #   FileUtils.ln('tmp0/t.txt', 'tmp1/t.lnk') # => 0
+  #   Dir.children('tmp1/')                    # => ["t.lnk"]
+  #
+  # When +src+ is the path to an existing file
+  # and +dest+ is the path to an existing directory,
+  # creates a hard link at <tt>dest/src</tt> pointing to +src+; returns zero:
   #
-  # Options: force noop verbose
+  #   Dir.children('tmp2')               # => ["t.dat"]
+  #   Dir.children('tmp3')               # => []
+  #   FileUtils.ln('tmp2/t.dat', 'tmp3') # => 0
+  #   Dir.children('tmp3')               # => ["t.dat"]
   #
-  # <b><tt>ln(old, new, options = {})</tt></b>
+  # When +src+ is an array of paths to existing files
+  # and +dest+ is the path to an existing directory,
+  # then for each path +target+ in +src+,
+  # creates a hard link at <tt>dest/target</tt> pointing to +target+;
+  # returns +src+:
   #
-  # Creates a hard link +new+ which points to +old+.
-  # If +new+ already exists and it is a directory, creates a link +new/old+.
-  # If +new+ already exists and it is not a directory, raises Errno::EEXIST.
-  # But if :force option is set, overwrite +new+.
+  #   Dir.children('tmp4/')                               # => []
+  #   FileUtils.ln(['tmp0/t.txt', 'tmp2/t.dat'], 'tmp4/') # => ["tmp0/t.txt", "tmp2/t.dat"]
+  #   Dir.children('tmp4/')                               # => ["t.dat", "t.txt"]
   #
-  #   FileUtils.ln 'gcc', 'cc', :verbose => true
-  #   FileUtils.ln '/usr/bin/emacs21', '/usr/bin/emacs'
+  # Keyword arguments:
   #
-  # <b><tt>ln(list, destdir, options = {})</tt></b>
+  # - <tt>force: true</tt> - overwrites +dest+ if it exists.
+  # - <tt>noop: true</tt> - does not create links.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
   #
-  # Creates several hard links in a directory, with each one pointing to the
-  # item in +list+.  If +destdir+ is not a directory, raises Errno::ENOTDIR.
+  #     FileUtils.ln('tmp0/t.txt', 'tmp1/t.lnk', verbose: true)
+  #     FileUtils.ln('tmp2/t.dat', 'tmp3', verbose: true)
+  #     FileUtils.ln(['tmp0/t.txt', 'tmp2/t.dat'], 'tmp4/', verbose: true)
   #
-  #   include FileUtils
-  #   cd '/sbin'
-  #   FileUtils.ln %w(cp mv mkdir), '/bin'   # Now /sbin/cp and /bin/cp are linked.
+  #   Output:
   #
-  def ln(src, dest, options = {})
-    fu_check_options options, OPT_TABLE['ln']
-    fu_output_message "ln#{options[:force] ? ' -f' : ''} #{[src,dest].flatten.join ' '}" if options[:verbose]
-    return if options[:noop]
+  #     ln tmp0/t.txt tmp1/t.lnk
+  #     ln tmp2/t.dat tmp3
+  #     ln tmp0/t.txt tmp2/t.dat tmp4/
+  #
+  # Raises an exception if +dest+ is the path to an existing file
+  # and keyword argument +force+ is not +true+.
+  #
+  # Related: FileUtils.link_entry (has different options).
+  #
+  def ln(src, dest, force: nil, noop: nil, verbose: nil)
+    fu_output_message "ln#{force ? ' -f' : ''} #{[src,dest].flatten.join ' '}" if verbose
+    return if noop
     fu_each_src_dest0(src, dest) do |s,d|
-      remove_file d, true if options[:force]
+      remove_file d, true if force
       File.link s, d
     end
   end
@@ -317,37 +527,192 @@ module FileUtils
   alias link ln
   module_function :link
 
-  OPT_TABLE['ln']   =
-  OPT_TABLE['link'] = [:force, :noop, :verbose]
+  # Creates {hard links}[https://en.wikipedia.org/wiki/Hard_link].
+  #
+  # Arguments +src+ (a single path or an array of paths)
+  # and +dest+ (a single path)
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # If +src+ is the path to a directory and +dest+ does not exist,
+  # creates links +dest+ and descendents pointing to +src+ and its descendents:
+  #
+  #   tree('src0')
+  #   # => src0
+  #   #    |-- sub0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- sub1
+  #   #        |-- src2.txt
+  #   #        `-- src3.txt
+  #   File.exist?('dest0') # => false
+  #   FileUtils.cp_lr('src0', 'dest0')
+  #   tree('dest0')
+  #   # => dest0
+  #   #    |-- sub0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- sub1
+  #   #        |-- src2.txt
+  #   #        `-- src3.txt
+  #
+  # If +src+ and +dest+ are both paths to directories,
+  # creates links <tt>dest/src</tt> and descendents
+  # pointing to +src+ and its descendents:
+  #
+  #   tree('src1')
+  #   # => src1
+  #   #    |-- sub0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- sub1
+  #   #        |-- src2.txt
+  #   #        `-- src3.txt
+  #   FileUtils.mkdir('dest1')
+  #   FileUtils.cp_lr('src1', 'dest1')
+  #   tree('dest1')
+  #   # => dest1
+  #   #    `-- src1
+  #   #        |-- sub0
+  #   #        |   |-- src0.txt
+  #   #        |   `-- src1.txt
+  #   #        `-- sub1
+  #   #            |-- src2.txt
+  #   #            `-- src3.txt
+  #
+  # If +src+ is an array of paths to entries and +dest+ is the path to a directory,
+  # for each path +filepath+ in +src+, creates a link at <tt>dest/filepath</tt>
+  # pointing to that path:
+  #
+  #   tree('src2')
+  #   # => src2
+  #   #    |-- sub0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- sub1
+  #   #        |-- src2.txt
+  #   #        `-- src3.txt
+  #   FileUtils.mkdir('dest2')
+  #   FileUtils.cp_lr(['src2/sub0', 'src2/sub1'], 'dest2')
+  #   tree('dest2')
+  #   # => dest2
+  #   #    |-- sub0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- sub1
+  #   #        |-- src2.txt
+  #   #        `-- src3.txt
+  #
+  # Keyword arguments:
+  #
+  # - <tt>dereference_root: false</tt> - if +src+ is a symbolic link,
+  #   does not dereference it.
+  # - <tt>noop: true</tt> - does not create links.
+  # - <tt>remove_destination: true</tt> - removes +dest+ before creating links.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     FileUtils.cp_lr('src0', 'dest0', noop: true, verbose: true)
+  #     FileUtils.cp_lr('src1', 'dest1', noop: true, verbose: true)
+  #     FileUtils.cp_lr(['src2/sub0', 'src2/sub1'], 'dest2', noop: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     cp -lr src0 dest0
+  #     cp -lr src1 dest1
+  #     cp -lr src2/sub0 src2/sub1 dest2
+  #
+  # Raises an exception if +dest+ is the path to an existing file or directory
+  # and keyword argument <tt>remove_destination: true</tt> is not given.
+  #
+  # Related: {methods for copying}[rdoc-ref:FileUtils@Copying].
+  #
+  def cp_lr(src, dest, noop: nil, verbose: nil,
+            dereference_root: true, remove_destination: false)
+    fu_output_message "cp -lr#{remove_destination ? ' --remove-destination' : ''} #{[src,dest].flatten.join ' '}" if verbose
+    return if noop
+    fu_each_src_dest(src, dest) do |s, d|
+      link_entry s, d, dereference_root, remove_destination
+    end
+  end
+  module_function :cp_lr
 
+  # Creates {symbolic links}[https://en.wikipedia.org/wiki/Symbolic_link].
   #
-  # Options: force noop verbose
+  # Arguments +src+ (a single path or an array of paths)
+  # and +dest+ (a single path)
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
   #
-  # <b><tt>ln_s(old, new, options = {})</tt></b>
+  # If +src+ is the path to an existing file:
   #
-  # Creates a symbolic link +new+ which points to +old+.  If +new+ already
-  # exists and it is a directory, creates a symbolic link +new/old+.  If +new+
-  # already exists and it is not a directory, raises Errno::EEXIST.  But if
-  # :force option is set, overwrite +new+.
+  # - When +dest+ is the path to a non-existent file,
+  #   creates a symbolic link at +dest+ pointing to +src+:
   #
-  #   FileUtils.ln_s '/usr/bin/ruby', '/usr/local/bin/ruby'
-  #   FileUtils.ln_s 'verylongsourcefilename.c', 'c', :force => true
+  #     FileUtils.touch('src0.txt')
+  #     File.exist?('dest0.txt')   # => false
+  #     FileUtils.ln_s('src0.txt', 'dest0.txt')
+  #     File.symlink?('dest0.txt') # => true
   #
-  # <b><tt>ln_s(list, destdir, options = {})</tt></b>
+  # - When +dest+ is the path to an existing file,
+  #   creates a symbolic link at +dest+ pointing to +src+
+  #   if and only if keyword argument <tt>force: true</tt> is given
+  #   (raises an exception otherwise):
   #
-  # Creates several symbolic links in a directory, with each one pointing to the
-  # item in +list+.  If +destdir+ is not a directory, raises Errno::ENOTDIR.
+  #     FileUtils.touch('src1.txt')
+  #     FileUtils.touch('dest1.txt')
+  #     FileUtils.ln_s('src1.txt', 'dest1.txt', force: true)
+  #     FileTest.symlink?('dest1.txt') # => true
   #
-  # If +destdir+ is not a directory, raises Errno::ENOTDIR.
+  #     FileUtils.ln_s('src1.txt', 'dest1.txt') # Raises Errno::EEXIST.
   #
-  #   FileUtils.ln_s Dir.glob('bin/*.rb'), '/home/aamine/bin'
+  # If +dest+ is the path to a directory,
+  # creates a symbolic link at <tt>dest/src</tt> pointing to +src+:
   #
-  def ln_s(src, dest, options = {})
-    fu_check_options options, OPT_TABLE['ln_s']
-    fu_output_message "ln -s#{options[:force] ? 'f' : ''} #{[src,dest].flatten.join ' '}" if options[:verbose]
-    return if options[:noop]
-    fu_each_src_dest0(src, dest) do |s,d|
-      remove_file d, true if options[:force]
+  #   FileUtils.touch('src2.txt')
+  #   FileUtils.mkdir('destdir2')
+  #   FileUtils.ln_s('src2.txt', 'destdir2')
+  #   File.symlink?('destdir2/src2.txt') # => true
+  #
+  # If +src+ is an array of paths to existing files and +dest+ is a directory,
+  # for each child +child+ in +src+ creates a symbolic link <tt>dest/child</tt>
+  # pointing to +child+:
+  #
+  #   FileUtils.mkdir('srcdir3')
+  #   FileUtils.touch('srcdir3/src0.txt')
+  #   FileUtils.touch('srcdir3/src1.txt')
+  #   FileUtils.mkdir('destdir3')
+  #   FileUtils.ln_s(['srcdir3/src0.txt', 'srcdir3/src1.txt'], 'destdir3')
+  #   File.symlink?('destdir3/src0.txt') # => true
+  #   File.symlink?('destdir3/src1.txt') # => true
+  #
+  # Keyword arguments:
+  #
+  # - <tt>force: true</tt> - overwrites +dest+ if it exists.
+  # - <tt>relative: false</tt> - create links relative to +dest+.
+  # - <tt>noop: true</tt> - does not create links.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     FileUtils.ln_s('src0.txt', 'dest0.txt', noop: true, verbose: true)
+  #     FileUtils.ln_s('src1.txt', 'destdir1', noop: true, verbose: true)
+  #     FileUtils.ln_s('src2.txt', 'dest2.txt', force: true, noop: true, verbose: true)
+  #     FileUtils.ln_s(['srcdir3/src0.txt', 'srcdir3/src1.txt'], 'destdir3', noop: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     ln -s src0.txt dest0.txt
+  #     ln -s src1.txt destdir1
+  #     ln -sf src2.txt dest2.txt
+  #     ln -s srcdir3/src0.txt srcdir3/src1.txt destdir3
+  #
+  # Related: FileUtils.ln_sf.
+  #
+  def ln_s(src, dest, force: nil, relative: false, target_directory: true, noop: nil, verbose: nil)
+    if relative
+      return ln_sr(src, dest, force: force, target_directory: target_directory, noop: noop, verbose: verbose)
+    end
+    fu_output_message "ln -s#{force ? 'f' : ''}#{
+      target_directory ? '' : 'T'} #{[src,dest].flatten.join ' '}" if verbose
+    return if noop
+    fu_each_src_dest0(src, dest, target_directory) do |s,d|
+      remove_file d, true if force
       File.symlink s, d
     end
   end
@@ -356,121 +721,354 @@ module FileUtils
   alias symlink ln_s
   module_function :symlink
 
-  OPT_TABLE['ln_s']    =
-  OPT_TABLE['symlink'] = [:force, :noop, :verbose]
-
-  #
-  # Options: noop verbose
-  #
-  # Same as
-  #   #ln_s(src, dest, :force)
+  # Like FileUtils.ln_s, but always with keyword argument <tt>force: true</tt> given.
   #
-  def ln_sf(src, dest, options = {})
-    fu_check_options options, OPT_TABLE['ln_sf']
-    options = options.dup
-    options[:force] = true
-    ln_s src, dest, options
+  def ln_sf(src, dest, noop: nil, verbose: nil)
+    ln_s src, dest, force: true, noop: noop, verbose: verbose
   end
   module_function :ln_sf
 
-  OPT_TABLE['ln_sf'] = [:noop, :verbose]
+  # Like FileUtils.ln_s, but create links relative to +dest+.
+  #
+  def ln_sr(src, dest, target_directory: true, force: nil, noop: nil, verbose: nil)
+    cmd = "ln -s#{force ? 'f' : ''}#{target_directory ? '' : 'T'}" if verbose
+    fu_each_src_dest0(src, dest, target_directory) do |s,d|
+      if target_directory
+        parent = File.dirname(d)
+        destdirs = fu_split_path(parent)
+        real_ddirs = fu_split_path(File.realpath(parent))
+      else
+        destdirs ||= fu_split_path(dest)
+        real_ddirs ||= fu_split_path(File.realdirpath(dest))
+      end
+      srcdirs = fu_split_path(s)
+      i = fu_common_components(srcdirs, destdirs)
+      n = destdirs.size - i
+      n -= 1 unless target_directory
+      link1 = fu_clean_components(*Array.new([n, 0].max, '..'), *srcdirs[i..-1])
+      begin
+        real_sdirs = fu_split_path(File.realdirpath(s)) rescue nil
+      rescue
+      else
+        i = fu_common_components(real_sdirs, real_ddirs)
+        n = real_ddirs.size - i
+        n -= 1 unless target_directory
+        link2 = fu_clean_components(*Array.new([n, 0].max, '..'), *real_sdirs[i..-1])
+        link1 = link2 if link1.size > link2.size
+      end
+      s = File.join(link1)
+      fu_output_message [cmd, s, d].flatten.join(' ') if verbose
+      next if noop
+      remove_file d, true if force
+      File.symlink s, d
+    end
+  end
+  module_function :ln_sr
 
+  # Creates {hard links}[https://en.wikipedia.org/wiki/Hard_link]; returns +nil+.
   #
-  # Options: preserve noop verbose
+  # Arguments +src+ and +dest+
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
   #
-  # Copies a file content +src+ to +dest+.  If +dest+ is a directory,
-  # copies +src+ to +dest/src+.
+  # If +src+ is the path to a file and +dest+ does not exist,
+  # creates a hard link at +dest+ pointing to +src+:
   #
-  # If +src+ is a list of files, then +dest+ must be a directory.
+  #   FileUtils.touch('src0.txt')
+  #   File.exist?('dest0.txt') # => false
+  #   FileUtils.link_entry('src0.txt', 'dest0.txt')
+  #   File.file?('dest0.txt')  # => true
   #
-  #   FileUtils.cp 'eval.c', 'eval.c.org'
-  #   FileUtils.cp %w(cgi.rb complex.rb date.rb), '/usr/lib/ruby/1.6'
-  #   FileUtils.cp %w(cgi.rb complex.rb date.rb), '/usr/lib/ruby/1.6', :verbose => true
-  #   FileUtils.cp 'symlink', 'dest'   # copy content, "dest" is not a symlink
+  # If +src+ is the path to a directory and +dest+ does not exist,
+  # recursively creates hard links at +dest+ pointing to paths in +src+:
   #
-  def cp(src, dest, options = {})
-    fu_check_options options, OPT_TABLE['cp']
-    fu_output_message "cp#{options[:preserve] ? ' -p' : ''} #{[src,dest].flatten.join ' '}" if options[:verbose]
-    return if options[:noop]
-    fu_each_src_dest(src, dest) do |s, d|
-      copy_file s, d, options[:preserve]
+  #   FileUtils.mkdir_p(['src1/dir0', 'src1/dir1'])
+  #   src_file_paths = [
+  #     'src1/dir0/t0.txt',
+  #     'src1/dir0/t1.txt',
+  #     'src1/dir1/t2.txt',
+  #     'src1/dir1/t3.txt',
+  #     ]
+  #   FileUtils.touch(src_file_paths)
+  #   File.directory?('dest1')        # => true
+  #   FileUtils.link_entry('src1', 'dest1')
+  #   File.file?('dest1/dir0/t0.txt') # => true
+  #   File.file?('dest1/dir0/t1.txt') # => true
+  #   File.file?('dest1/dir1/t2.txt') # => true
+  #   File.file?('dest1/dir1/t3.txt') # => true
+  #
+  # Optional arguments:
+  #
+  # - +dereference_root+ - dereferences +src+ if it is a symbolic link (+false+ by default).
+  # - +remove_destination+ - removes +dest+ before creating links (+false+ by default).
+  #
+  # Raises an exception if +dest+ is the path to an existing file or directory
+  # and optional argument +remove_destination+ is not given.
+  #
+  # Related: FileUtils.ln (has different options).
+  #
+  def link_entry(src, dest, dereference_root = false, remove_destination = false)
+    Entry_.new(src, nil, dereference_root).traverse do |ent|
+      destent = Entry_.new(dest, ent.rel, false)
+      File.unlink destent.path if remove_destination && File.file?(destent.path)
+      ent.link destent.path
     end
   end
-  module_function :cp
-
-  alias copy cp
-  module_function :copy
-
-  OPT_TABLE['cp']   =
-  OPT_TABLE['copy'] = [:preserve, :noop, :verbose]
+  module_function :link_entry
 
+  # Copies files.
+  #
+  # Arguments +src+ (a single path or an array of paths)
+  # and +dest+ (a single path)
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # If +src+ is the path to a file and +dest+ is not the path to a directory,
+  # copies +src+ to +dest+:
   #
-  # Options: preserve noop verbose dereference_root remove_destination
+  #   FileUtils.touch('src0.txt')
+  #   File.exist?('dest0.txt') # => false
+  #   FileUtils.cp('src0.txt', 'dest0.txt')
+  #   File.file?('dest0.txt')  # => true
   #
-  # Copies +src+ to +dest+. If +src+ is a directory, this method copies
-  # all its contents recursively. If +dest+ is a directory, copies
-  # +src+ to +dest/src+.
+  # If +src+ is the path to a file and +dest+ is the path to a directory,
+  # copies +src+ to <tt>dest/src</tt>:
   #
-  # +src+ can be a list of files.
+  #   FileUtils.touch('src1.txt')
+  #   FileUtils.mkdir('dest1')
+  #   FileUtils.cp('src1.txt', 'dest1')
+  #   File.file?('dest1/src1.txt') # => true
   #
-  #   # Installing ruby library "mylib" under the site_ruby
-  #   FileUtils.rm_r site_ruby + '/mylib', :force
-  #   FileUtils.cp_r 'lib/', site_ruby + '/mylib'
+  # If +src+ is an array of paths to files and +dest+ is the path to a directory,
+  # copies from each +src+ to +dest+:
   #
-  #   # Examples of copying several files to target directory.
-  #   FileUtils.cp_r %w(mail.rb field.rb debug/), site_ruby + '/tmail'
-  #   FileUtils.cp_r Dir.glob('*.rb'), '/home/aamine/lib/ruby', :noop => true, :verbose => true
+  #   src_file_paths = ['src2.txt', 'src2.dat']
+  #   FileUtils.touch(src_file_paths)
+  #   FileUtils.mkdir('dest2')
+  #   FileUtils.cp(src_file_paths, 'dest2')
+  #   File.file?('dest2/src2.txt') # => true
+  #   File.file?('dest2/src2.dat') # => true
   #
-  #   # If you want to copy all contents of a directory instead of the
-  #   # directory itself, c.f. src/x -> dest/x, src/y -> dest/y,
-  #   # use following code.
-  #   FileUtils.cp_r 'src/.', 'dest'     # cp_r('src', 'dest') makes src/dest,
-  #                                      # but this doesn't.
+  # Keyword arguments:
   #
-  def cp_r(src, dest, options = {})
-    fu_check_options options, OPT_TABLE['cp_r']
-    fu_output_message "cp -r#{options[:preserve] ? 'p' : ''}#{options[:remove_destination] ? ' --remove-destination' : ''} #{[src,dest].flatten.join ' '}" if options[:verbose]
-    return if options[:noop]
-    options = options.dup
-    options[:dereference_root] = true unless options.key?(:dereference_root)
+  # - <tt>preserve: true</tt> - preserves file times.
+  # - <tt>noop: true</tt> - does not copy files.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     FileUtils.cp('src0.txt', 'dest0.txt', noop: true, verbose: true)
+  #     FileUtils.cp('src1.txt', 'dest1', noop: true, verbose: true)
+  #     FileUtils.cp(src_file_paths, 'dest2', noop: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     cp src0.txt dest0.txt
+  #     cp src1.txt dest1
+  #     cp src2.txt src2.dat dest2
+  #
+  # Raises an exception if +src+ is a directory.
+  #
+  # Related: {methods for copying}[rdoc-ref:FileUtils@Copying].
+  #
+  def cp(src, dest, preserve: nil, noop: nil, verbose: nil)
+    fu_output_message "cp#{preserve ? ' -p' : ''} #{[src,dest].flatten.join ' '}" if verbose
+    return if noop
     fu_each_src_dest(src, dest) do |s, d|
-      copy_entry s, d, options[:preserve], options[:dereference_root], options[:remove_destination]
+      copy_file s, d, preserve
     end
   end
-  module_function :cp_r
+  module_function :cp
+
+  alias copy cp
+  module_function :copy
 
-  OPT_TABLE['cp_r'] = [:preserve, :noop, :verbose,
-                       :dereference_root, :remove_destination]
+  # Recursively copies files.
+  #
+  # Arguments +src+ (a single path or an array of paths)
+  # and +dest+ (a single path)
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # The mode, owner, and group are retained in the copy;
+  # to change those, use FileUtils.install instead.
+  #
+  # If +src+ is the path to a file and +dest+ is not the path to a directory,
+  # copies +src+ to +dest+:
+  #
+  #   FileUtils.touch('src0.txt')
+  #   File.exist?('dest0.txt') # => false
+  #   FileUtils.cp_r('src0.txt', 'dest0.txt')
+  #   File.file?('dest0.txt')  # => true
+  #
+  # If +src+ is the path to a file and +dest+ is the path to a directory,
+  # copies +src+ to <tt>dest/src</tt>:
+  #
+  #   FileUtils.touch('src1.txt')
+  #   FileUtils.mkdir('dest1')
+  #   FileUtils.cp_r('src1.txt', 'dest1')
+  #   File.file?('dest1/src1.txt') # => true
+  #
+  # If +src+ is the path to a directory and +dest+ does not exist,
+  # recursively copies +src+ to +dest+:
+  #
+  #   tree('src2')
+  #   # => src2
+  #   #    |-- dir0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- dir1
+  #   #    |-- src2.txt
+  #   #    `-- src3.txt
+  #   FileUtils.exist?('dest2') # => false
+  #   FileUtils.cp_r('src2', 'dest2')
+  #   tree('dest2')
+  #   # => dest2
+  #   #    |-- dir0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- dir1
+  #   #    |-- src2.txt
+  #   #    `-- src3.txt
+  #
+  # If +src+ and +dest+ are paths to directories,
+  # recursively copies +src+ to <tt>dest/src</tt>:
+  #
+  #   tree('src3')
+  #   # => src3
+  #   #    |-- dir0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- dir1
+  #   #    |-- src2.txt
+  #   #    `-- src3.txt
+  #   FileUtils.mkdir('dest3')
+  #   FileUtils.cp_r('src3', 'dest3')
+  #   tree('dest3')
+  #   # => dest3
+  #   #    `-- src3
+  #   #      |-- dir0
+  #   #      |   |-- src0.txt
+  #   #      |   `-- src1.txt
+  #   #      `-- dir1
+  #   #          |-- src2.txt
+  #   #          `-- src3.txt
+  #
+  # If +src+ is an array of paths and +dest+ is a directory,
+  # recursively copies from each path in +src+ to +dest+;
+  # the paths in +src+ may point to files and/or directories.
+  #
+  # Keyword arguments:
+  #
+  # - <tt>dereference_root: false</tt> - if +src+ is a symbolic link,
+  #   does not dereference it.
+  # - <tt>noop: true</tt> - does not copy files.
+  # - <tt>preserve: true</tt> - preserves file times.
+  # - <tt>remove_destination: true</tt> - removes +dest+ before copying files.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     FileUtils.cp_r('src0.txt', 'dest0.txt', noop: true, verbose: true)
+  #     FileUtils.cp_r('src1.txt', 'dest1', noop: true, verbose: true)
+  #     FileUtils.cp_r('src2', 'dest2', noop: true, verbose: true)
+  #     FileUtils.cp_r('src3', 'dest3', noop: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     cp -r src0.txt dest0.txt
+  #     cp -r src1.txt dest1
+  #     cp -r src2 dest2
+  #     cp -r src3 dest3
+  #
+  # Raises an exception of +src+ is the path to a directory
+  # and +dest+ is the path to a file.
+  #
+  # Related: {methods for copying}[rdoc-ref:FileUtils@Copying].
+  #
+  def cp_r(src, dest, preserve: nil, noop: nil, verbose: nil,
+           dereference_root: true, remove_destination: nil)
+    fu_output_message "cp -r#{preserve ? 'p' : ''}#{remove_destination ? ' --remove-destination' : ''} #{[src,dest].flatten.join ' '}" if verbose
+    return if noop
+    fu_each_src_dest(src, dest) do |s, d|
+      copy_entry s, d, preserve, dereference_root, remove_destination
+    end
+  end
+  module_function :cp_r
 
+  # Recursively copies files from +src+ to +dest+.
+  #
+  # Arguments +src+ and +dest+
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # If +src+ is the path to a file, copies +src+ to +dest+:
   #
-  # Copies a file system entry +src+ to +dest+.
-  # If +src+ is a directory, this method copies its contents recursively.
-  # This method preserves file types, c.f. symlink, directory...
-  # (FIFO, device files and etc. are not supported yet)
+  #   FileUtils.touch('src0.txt')
+  #   File.exist?('dest0.txt') # => false
+  #   FileUtils.copy_entry('src0.txt', 'dest0.txt')
+  #   File.file?('dest0.txt')  # => true
   #
-  # Both of +src+ and +dest+ must be a path name.
-  # +src+ must exist, +dest+ must not exist.
+  # If +src+ is a directory, recursively copies +src+ to +dest+:
   #
-  # If +preserve+ is true, this method preserves owner, group, permissions
-  # and modified time.
+  #   tree('src1')
+  #   # => src1
+  #   #    |-- dir0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- dir1
+  #   #        |-- src2.txt
+  #   #        `-- src3.txt
+  #   FileUtils.copy_entry('src1', 'dest1')
+  #   tree('dest1')
+  #   # => dest1
+  #   #    |-- dir0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- dir1
+  #   #        |-- src2.txt
+  #   #        `-- src3.txt
   #
-  # If +dereference_root+ is true, this method dereference tree root.
+  # The recursive copying preserves file types for regular files,
+  # directories, and symbolic links;
+  # other file types (FIFO streams, device files, etc.) are not supported.
   #
-  # If +remove_destination+ is true, this method removes each destination file before copy.
+  # Optional arguments:
+  #
+  # - +dereference_root+ - if +src+ is a symbolic link,
+  #   follows the link (+false+ by default).
+  # - +preserve+ - preserves file times (+false+ by default).
+  # - +remove_destination+ - removes +dest+ before copying files (+false+ by default).
+  #
+  # Related: {methods for copying}[rdoc-ref:FileUtils@Copying].
   #
   def copy_entry(src, dest, preserve = false, dereference_root = false, remove_destination = false)
-    Entry_.new(src, nil, dereference_root).traverse do |ent|
+    if dereference_root
+      src = File.realpath(src)
+    end
+
+    Entry_.new(src, nil, false).wrap_traverse(proc do |ent|
       destent = Entry_.new(dest, ent.rel, false)
-      File.unlink destent.path if remove_destination && File.file?(destent.path)
+      File.unlink destent.path if remove_destination && (File.file?(destent.path) || File.symlink?(destent.path))
       ent.copy destent.path
+    end, proc do |ent|
+      destent = Entry_.new(dest, ent.rel, false)
       ent.copy_metadata destent.path if preserve
-    end
+    end)
   end
   module_function :copy_entry
 
+  # Copies file from +src+ to +dest+, which should not be directories.
+  #
+  # Arguments +src+ and +dest+
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # Examples:
+  #
+  #   FileUtils.touch('src0.txt')
+  #   FileUtils.copy_file('src0.txt', 'dest0.txt')
+  #   File.file?('dest0.txt') # => true
+  #
+  # Optional arguments:
   #
-  # Copies file contents of +src+ to +dest+.
-  # Both of +src+ and +dest+ must be a path name.
+  # - +dereference+ - if +src+ is a symbolic link,
+  #   follows the link (+true+ by default).
+  # - +preserve+ - preserves file times (+false+ by default).
+  # - +remove_destination+ - removes +dest+ before copying files (+false+ by default).
+  #
+  # Related: {methods for copying}[rdoc-ref:FileUtils@Copying].
   #
   def copy_file(src, dest, preserve = false, dereference = true)
     ent = Entry_.new(src, nil, dereference)
@@ -479,54 +1077,104 @@ module FileUtils
   end
   module_function :copy_file
 
+  # Copies \IO stream +src+ to \IO stream +dest+ via
+  # {IO.copy_stream}[rdoc-ref:IO.copy_stream].
   #
-  # Copies stream +src+ to +dest+.
-  # +src+ must respond to #read(n) and
-  # +dest+ must respond to #write(str).
+  # Related: {methods for copying}[rdoc-ref:FileUtils@Copying].
   #
   def copy_stream(src, dest)
     IO.copy_stream(src, dest)
   end
   module_function :copy_stream
 
-  #
-  # Options: force noop verbose
-  #
-  # Moves file(s) +src+ to +dest+.  If +file+ and +dest+ exist on the different
-  # disk partition, the file is copied then the original file is removed.
-  #
-  #   FileUtils.mv 'badname.rb', 'goodname.rb'
-  #   FileUtils.mv 'stuff.rb', '/notexist/lib/ruby', :force => true  # no error
-  #
-  #   FileUtils.mv %w(junk.txt dust.txt), '/home/aamine/.trash/'
-  #   FileUtils.mv Dir.glob('test*.rb'), 'test', :noop => true, :verbose => true
-  #
-  def mv(src, dest, options = {})
-    fu_check_options options, OPT_TABLE['mv']
-    fu_output_message "mv#{options[:force] ? ' -f' : ''} #{[src,dest].flatten.join ' '}" if options[:verbose]
-    return if options[:noop]
+  # Moves entries.
+  #
+  # Arguments +src+ (a single path or an array of paths)
+  # and +dest+ (a single path)
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # If +src+ and +dest+ are on different file systems,
+  # first copies, then removes +src+.
+  #
+  # May cause a local vulnerability if not called with keyword argument
+  # <tt>secure: true</tt>;
+  # see {Avoiding the TOCTTOU Vulnerability}[rdoc-ref:FileUtils@Avoiding+the+TOCTTOU+Vulnerability].
+  #
+  # If +src+ is the path to a single file or directory and +dest+ does not exist,
+  # moves +src+ to +dest+:
+  #
+  #   tree('src0')
+  #   # => src0
+  #   #    |-- src0.txt
+  #   #    `-- src1.txt
+  #   File.exist?('dest0') # => false
+  #   FileUtils.mv('src0', 'dest0')
+  #   File.exist?('src0')  # => false
+  #   tree('dest0')
+  #   # => dest0
+  #   #    |-- src0.txt
+  #   #    `-- src1.txt
+  #
+  # If +src+ is an array of paths to files and directories
+  # and +dest+ is the path to a directory,
+  # copies from each path in the array to +dest+:
+  #
+  #   File.file?('src1.txt') # => true
+  #   tree('src1')
+  #   # => src1
+  #   #    |-- src.dat
+  #   #    `-- src.txt
+  #   Dir.empty?('dest1')    # => true
+  #   FileUtils.mv(['src1.txt', 'src1'], 'dest1')
+  #   tree('dest1')
+  #   # => dest1
+  #   #    |-- src1
+  #   #    |   |-- src.dat
+  #   #    |   `-- src.txt
+  #   #    `-- src1.txt
+  #
+  # Keyword arguments:
+  #
+  # - <tt>force: true</tt> - if the move includes removing +src+
+  #   (that is, if +src+ and +dest+ are on different file systems),
+  #   ignores raised exceptions of StandardError and its descendants.
+  # - <tt>noop: true</tt> - does not move files.
+  # - <tt>secure: true</tt> - removes +src+ securely;
+  #   see details at FileUtils.remove_entry_secure.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     FileUtils.mv('src0', 'dest0', noop: true, verbose: true)
+  #     FileUtils.mv(['src1.txt', 'src1'], 'dest1', noop: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     mv src0 dest0
+  #     mv src1.txt src1 dest1
+  #
+  def mv(src, dest, force: nil, noop: nil, verbose: nil, secure: nil)
+    fu_output_message "mv#{force ? ' -f' : ''} #{[src,dest].flatten.join ' '}" if verbose
+    return if noop
     fu_each_src_dest(src, dest) do |s, d|
       destent = Entry_.new(d, nil, true)
       begin
         if destent.exist?
           if destent.directory?
-            raise Errno::EEXIST, dest
-          else
-            destent.remove_file if rename_cannot_overwrite_file?
+            raise Errno::EEXIST, d
           end
         end
         begin
           File.rename s, d
-        rescue Errno::EXDEV
+        rescue Errno::EXDEV,
+               Errno::EPERM # move from unencrypted to encrypted dir (ext4)
           copy_entry s, d, true
-          if options[:secure]
-            remove_entry_secure s, options[:force]
+          if secure
+            remove_entry_secure s, force
           else
-            remove_entry s, options[:force]
+            remove_entry s, force
           end
         end
       rescue SystemCallError
-        raise unless options[:force]
+        raise unless force
       end
     end
   end
@@ -535,32 +1183,40 @@ module FileUtils
   alias move mv
   module_function :move
 
-  OPT_TABLE['mv']   =
-  OPT_TABLE['move'] = [:force, :noop, :verbose, :secure]
-
-  def rename_cannot_overwrite_file?   #:nodoc:
-    /cygwin|mswin|mingw|bccwin|emx/ =~ RUBY_PLATFORM
-  end
-  private_module_function :rename_cannot_overwrite_file?
-
+  # Removes entries at the paths in the given +list+
+  # (a single path or an array of paths)
+  # returns +list+, if it is an array, <tt>[list]</tt> otherwise.
+  #
+  # Argument +list+ or its elements
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # With no keyword arguments, removes files at the paths given in +list+:
+  #
+  #   FileUtils.touch(['src0.txt', 'src0.dat'])
+  #   FileUtils.rm(['src0.dat', 'src0.txt']) # => ["src0.dat", "src0.txt"]
+  #
+  # Keyword arguments:
+  #
+  # - <tt>force: true</tt> - ignores raised exceptions of StandardError
+  #   and its descendants.
+  # - <tt>noop: true</tt> - does not remove files; returns +nil+.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     FileUtils.rm(['src0.dat', 'src0.txt'], noop: true, verbose: true)
   #
-  # Options: force noop verbose
+  #   Output:
   #
-  # Remove file(s) specified in +list+.  This method cannot remove directories.
-  # All StandardErrors are ignored when the :force option is set.
+  #     rm src0.dat src0.txt
   #
-  #   FileUtils.rm %w( junk.txt dust.txt )
-  #   FileUtils.rm Dir.glob('*.so')
-  #   FileUtils.rm 'NotExistFile', :force => true   # never raises exception
+  # Related: {methods for deleting}[rdoc-ref:FileUtils@Deleting].
   #
-  def rm(list, options = {})
-    fu_check_options options, OPT_TABLE['rm']
+  def rm(list, force: nil, noop: nil, verbose: nil)
     list = fu_list(list)
-    fu_output_message "rm#{options[:force] ? ' -f' : ''} #{list.join ' '}" if options[:verbose]
-    return if options[:noop]
+    fu_output_message "rm#{force ? ' -f' : ''} #{list.join ' '}" if verbose
+    return if noop
 
     list.each do |path|
-      remove_file path, options[:force]
+      remove_file path, force
     end
   end
   module_function :rm
@@ -568,124 +1224,126 @@ module FileUtils
   alias remove rm
   module_function :remove
 
-  OPT_TABLE['rm']     =
-  OPT_TABLE['remove'] = [:force, :noop, :verbose]
-
+  # Equivalent to:
+  #
+  #   FileUtils.rm(list, force: true, **kwargs)
   #
-  # Options: noop verbose
+  # Argument +list+ (a single path or an array of paths)
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
   #
-  # Equivalent to
+  # See FileUtils.rm for keyword arguments.
   #
-  #   #rm(list, :force => true)
+  # Related: {methods for deleting}[rdoc-ref:FileUtils@Deleting].
   #
-  def rm_f(list, options = {})
-    fu_check_options options, OPT_TABLE['rm_f']
-    options = options.dup
-    options[:force] = true
-    rm list, options
+  def rm_f(list, noop: nil, verbose: nil)
+    rm list, force: true, noop: noop, verbose: verbose
   end
   module_function :rm_f
 
   alias safe_unlink rm_f
   module_function :safe_unlink
 
-  OPT_TABLE['rm_f']        =
-  OPT_TABLE['safe_unlink'] = [:noop, :verbose]
-
+  # Removes entries at the paths in the given +list+
+  # (a single path or an array of paths);
+  # returns +list+, if it is an array, <tt>[list]</tt> otherwise.
+  #
+  # Argument +list+ or its elements
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # May cause a local vulnerability if not called with keyword argument
+  # <tt>secure: true</tt>;
+  # see {Avoiding the TOCTTOU Vulnerability}[rdoc-ref:FileUtils@Avoiding+the+TOCTTOU+Vulnerability].
+  #
+  # For each file path, removes the file at that path:
   #
-  # Options: force noop verbose secure
+  #   FileUtils.touch(['src0.txt', 'src0.dat'])
+  #   FileUtils.rm_r(['src0.dat', 'src0.txt'])
+  #   File.exist?('src0.txt') # => false
+  #   File.exist?('src0.dat') # => false
   #
-  # remove files +list+[0] +list+[1]... If +list+[n] is a directory,
-  # removes its all contents recursively. This method ignores
-  # StandardError when :force option is set.
+  # For each directory path, recursively removes files and directories:
   #
-  #   FileUtils.rm_r Dir.glob('/tmp/*')
-  #   FileUtils.rm_r '/', :force => true          #  :-)
+  #   tree('src1')
+  #   # => src1
+  #   #    |-- dir0
+  #   #    |   |-- src0.txt
+  #   #    |   `-- src1.txt
+  #   #    `-- dir1
+  #   #        |-- src2.txt
+  #   #        `-- src3.txt
+  #   FileUtils.rm_r('src1')
+  #   File.exist?('src1') # => false
   #
-  # WARNING: This method causes local vulnerability
-  # if one of parent directories or removing directory tree are world
-  # writable (including /tmp, whose permission is 1777), and the current
-  # process has strong privilege such as Unix super user (root), and the
-  # system has symbolic link.  For secure removing, read the documentation
-  # of #remove_entry_secure carefully, and set :secure option to true.
-  # Default is :secure=>false.
+  # Keyword arguments:
   #
-  # NOTE: This method calls #remove_entry_secure if :secure option is set.
-  # See also #remove_entry_secure.
+  # - <tt>force: true</tt> - ignores raised exceptions of StandardError
+  #   and its descendants.
+  # - <tt>noop: true</tt> - does not remove entries; returns +nil+.
+  # - <tt>secure: true</tt> - removes +src+ securely;
+  #   see details at FileUtils.remove_entry_secure.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
   #
-  def rm_r(list, options = {})
-    fu_check_options options, OPT_TABLE['rm_r']
-    # options[:secure] = true unless options.key?(:secure)
+  #     FileUtils.rm_r(['src0.dat', 'src0.txt'], noop: true, verbose: true)
+  #     FileUtils.rm_r('src1', noop: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     rm -r src0.dat src0.txt
+  #     rm -r src1
+  #
+  # Related: {methods for deleting}[rdoc-ref:FileUtils@Deleting].
+  #
+  def rm_r(list, force: nil, noop: nil, verbose: nil, secure: nil)
     list = fu_list(list)
-    fu_output_message "rm -r#{options[:force] ? 'f' : ''} #{list.join ' '}" if options[:verbose]
-    return if options[:noop]
+    fu_output_message "rm -r#{force ? 'f' : ''} #{list.join ' '}" if verbose
+    return if noop
     list.each do |path|
-      if options[:secure]
-        remove_entry_secure path, options[:force]
+      if secure
+        remove_entry_secure path, force
       else
-        remove_entry path, options[:force]
+        remove_entry path, force
       end
     end
   end
   module_function :rm_r
 
-  OPT_TABLE['rm_r'] = [:force, :noop, :verbose, :secure]
-
+  # Equivalent to:
   #
-  # Options: noop verbose secure
+  #   FileUtils.rm_r(list, force: true, **kwargs)
   #
-  # Equivalent to
+  # Argument +list+ or its elements
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
   #
-  #   #rm_r(list, :force => true)
+  # May cause a local vulnerability if not called with keyword argument
+  # <tt>secure: true</tt>;
+  # see {Avoiding the TOCTTOU Vulnerability}[rdoc-ref:FileUtils@Avoiding+the+TOCTTOU+Vulnerability].
   #
-  # WARNING: This method causes local vulnerability.
-  # Read the documentation of #rm_r first.
+  # See FileUtils.rm_r for keyword arguments.
   #
-  def rm_rf(list, options = {})
-    fu_check_options options, OPT_TABLE['rm_rf']
-    options = options.dup
-    options[:force] = true
-    rm_r list, options
+  # Related: {methods for deleting}[rdoc-ref:FileUtils@Deleting].
+  #
+  def rm_rf(list, noop: nil, verbose: nil, secure: nil)
+    rm_r list, force: true, noop: noop, verbose: verbose, secure: secure
   end
   module_function :rm_rf
 
   alias rmtree rm_rf
   module_function :rmtree
 
-  OPT_TABLE['rm_rf']  =
-  OPT_TABLE['rmtree'] = [:noop, :verbose, :secure]
-
-  #
-  # This method removes a file system entry +path+.  +path+ shall be a
-  # regular file, a directory, or something.  If +path+ is a directory,
-  # remove it recursively.  This method is required to avoid TOCTTOU
-  # (time-of-check-to-time-of-use) local security vulnerability of #rm_r.
-  # #rm_r causes security hole when:
-  #
-  #   * Parent directory is world writable (including /tmp).
-  #   * Removing directory tree includes world writable directory.
-  #   * The system has symbolic link.
-  #
-  # To avoid this security hole, this method applies special preprocess.
-  # If +path+ is a directory, this method chown(2) and chmod(2) all
-  # removing directories.  This requires the current process is the
-  # owner of the removing whole directory tree, or is the super user (root).
-  #
-  # WARNING: You must ensure that *ALL* parent directories cannot be
-  # moved by other untrusted users.  For example, parent directories
-  # should not be owned by untrusted users, and should not be world
-  # writable except when the sticky bit set.
+  # Securely removes the entry given by +path+,
+  # which should be the entry for a regular file, a symbolic link,
+  # or a directory.
   #
-  # WARNING: Only the owner of the removing directory tree, or Unix super
-  # user (root) should invoke this method.  Otherwise this method does not
-  # work.
+  # Argument +path+
+  # should be {interpretable as a path}[rdoc-ref:FileUtils@Path+Arguments].
   #
-  # For details of this security vulnerability, see Perl's case:
+  # Avoids a local vulnerability that can exist in certain circumstances;
+  # see {Avoiding the TOCTTOU Vulnerability}[rdoc-ref:FileUtils@Avoiding+the+TOCTTOU+Vulnerability].
   #
-  #   http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-0448
-  #   http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2004-0452
+  # Optional argument +force+ specifies whether to ignore
+  # raised exceptions of StandardError and its descendants.
   #
-  # For fileutils.rb, this vulnerability is reported in [ruby-dev:26100].
+  # Related: {methods for deleting}[rdoc-ref:FileUtils@Deleting].
   #
   def remove_entry_secure(path, force = false)
     unless fu_have_symlink?
@@ -707,22 +1365,38 @@ module FileUtils
     unless parent_st.sticky?
       raise ArgumentError, "parent directory is world writable, FileUtils#remove_entry_secure does not work; abort: #{path.inspect} (parent directory mode #{'%o' % parent_st.mode})"
     end
+
     # freeze tree root
     euid = Process.euid
-    File.open(fullpath + '/.') {|f|
-      unless fu_stat_identical_entry?(st, f.stat)
-        # symlink (TOC-to-TOU attack?)
-        File.unlink fullpath
-        return
-      end
-      f.chown euid, -1
-      f.chmod 0700
-      unless fu_stat_identical_entry?(st, File.lstat(fullpath))
-        # TOC-to-TOU attack?
-        File.unlink fullpath
-        return
-      end
-    }
+    dot_file = fullpath + "/."
+    begin
+      File.open(dot_file) {|f|
+        unless fu_stat_identical_entry?(st, f.stat)
+          # symlink (TOC-to-TOU attack?)
+          File.unlink fullpath
+          return
+        end
+        f.chown euid, -1
+        f.chmod 0700
+      }
+    rescue Errno::EISDIR # JRuby in non-native mode can't open files as dirs
+      File.lstat(dot_file).tap {|fstat|
+        unless fu_stat_identical_entry?(st, fstat)
+          # symlink (TOC-to-TOU attack?)
+          File.unlink fullpath
+          return
+        end
+        File.chown euid, -1, dot_file
+        File.chmod 0700, dot_file
+      }
+    end
+
+    unless fu_stat_identical_entry?(st, File.lstat(fullpath))
+      # TOC-to-TOU attack?
+      File.unlink fullpath
+      return
+    end
+
     # ---- tree root is frozen ----
     root = Entry_.new(path)
     root.preorder_traverse do |ent|
@@ -747,7 +1421,7 @@ module FileUtils
     File.symlink nil, nil
   rescue NotImplementedError
     return false
-  rescue
+  rescue TypeError
     return true
   end
   private_module_function :fu_have_symlink?
@@ -757,12 +1431,17 @@ module FileUtils
   end
   private_module_function :fu_stat_identical_entry?
 
+  # Removes the entry given by +path+,
+  # which should be the entry for a regular file, a symbolic link,
+  # or a directory.
   #
-  # This method removes a file system entry +path+.
-  # +path+ might be a regular file, a directory, or something.
-  # If +path+ is a directory, remove it recursively.
+  # Argument +path+
+  # should be {interpretable as a path}[rdoc-ref:FileUtils@Path+Arguments].
   #
-  # See also #remove_entry_secure.
+  # Optional argument +force+ specifies whether to ignore
+  # raised exceptions of StandardError and its descendants.
+  #
+  # Related: FileUtils.remove_entry_secure.
   #
   def remove_entry(path, force = false)
     Entry_.new(path).postorder_traverse do |ent|
@@ -777,9 +1456,16 @@ module FileUtils
   end
   module_function :remove_entry
 
+  # Removes the file entry given by +path+,
+  # which should be the entry for a regular file or a symbolic link.
+  #
+  # Argument +path+
+  # should be {interpretable as a path}[rdoc-ref:FileUtils@Path+Arguments].
   #
-  # Removes a file +path+.
-  # This method ignores StandardError if +force+ is true.
+  # Optional argument +force+ specifies whether to ignore
+  # raised exceptions of StandardError and its descendants.
+  #
+  # Related: {methods for deleting}[rdoc-ref:FileUtils@Deleting].
   #
   def remove_file(path, force = false)
     Entry_.new(path).remove_file
@@ -788,20 +1474,33 @@ module FileUtils
   end
   module_function :remove_file
 
+  # Recursively removes the directory entry given by +path+,
+  # which should be the entry for a regular file, a symbolic link,
+  # or a directory.
+  #
+  # Argument +path+
+  # should be {interpretable as a path}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # Optional argument +force+ specifies whether to ignore
+  # raised exceptions of StandardError and its descendants.
   #
-  # Removes a directory +dir+ and its contents recursively.
-  # This method ignores StandardError if +force+ is true.
+  # Related: {methods for deleting}[rdoc-ref:FileUtils@Deleting].
   #
   def remove_dir(path, force = false)
-    remove_entry path, force   # FIXME?? check if it is a directory
+    raise Errno::ENOTDIR, path unless force or File.directory?(path)
+    remove_entry path, force
   end
   module_function :remove_dir
 
+  # Returns +true+ if the contents of files +a+ and +b+ are identical,
+  # +false+ otherwise.
   #
-  # Returns true if the contents of a file A and a file B are identical.
+  # Arguments +a+ and +b+
+  # should be {interpretable as a path}[rdoc-ref:FileUtils@Path+Arguments].
   #
-  #   FileUtils.compare_file('somefile', 'somefile')  #=> true
-  #   FileUtils.compare_file('/bin/cp', '/bin/mv')    #=> maybe false
+  # FileUtils.identical? and FileUtils.cmp are aliases for FileUtils.compare_file.
+  #
+  # Related: FileUtils.compare_stream.
   #
   def compare_file(a, b)
     return false unless File.size(a) == File.size(b)
@@ -818,109 +1517,201 @@ module FileUtils
   module_function :identical?
   module_function :cmp
 
+  # Returns +true+ if the contents of streams +a+ and +b+ are identical,
+  # +false+ otherwise.
+  #
+  # Arguments +a+ and +b+
+  # should be {interpretable as a path}[rdoc-ref:FileUtils@Path+Arguments].
   #
-  # Returns true if the contents of a stream +a+ and +b+ are identical.
+  # Related: FileUtils.compare_file.
   #
   def compare_stream(a, b)
     bsize = fu_stream_blksize(a, b)
-    sa = sb = nil
-    while sa == sb
-      sa = a.read(bsize)
-      sb = b.read(bsize)
-      unless sa and sb
-        if sa.nil? and sb.nil?
-          return true
-        end
-      end
-    end
+
+    sa = String.new(capacity: bsize)
+    sb = String.new(capacity: bsize)
+
+    begin
+      a.read(bsize, sa)
+      b.read(bsize, sb)
+      return true if sa.empty? && sb.empty?
+    end while sa == sb
     false
   end
   module_function :compare_stream
 
-  #
-  # Options: mode preserve noop verbose
-  #
-  # If +src+ is not same as +dest+, copies it and changes the permission
-  # mode to +mode+.  If +dest+ is a directory, destination is +dest+/+src+.
-  # This method removes destination before copy.
-  #
-  #   FileUtils.install 'ruby', '/usr/local/bin/ruby', :mode => 0755, :verbose => true
-  #   FileUtils.install 'lib.rb', '/usr/local/lib/ruby/site_ruby', :verbose => true
-  #
-  def install(src, dest, options = {})
-    fu_check_options options, OPT_TABLE['install']
-    fu_output_message "install -c#{options[:preserve] && ' -p'}#{options[:mode] ? (' -m 0%o' % options[:mode]) : ''} #{[src,dest].flatten.join ' '}" if options[:verbose]
-    return if options[:noop]
-    fu_each_src_dest(src, dest) do |s, d, st|
+  # Copies a file entry.
+  # See {install(1)}[https://man7.org/linux/man-pages/man1/install.1.html].
+  #
+  # Arguments +src+ (a single path or an array of paths)
+  # and +dest+ (a single path)
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments];
+  #
+  # If the entry at +dest+ does not exist, copies from +src+ to +dest+:
+  #
+  #   File.read('src0.txt')    # => "aaa\n"
+  #   File.exist?('dest0.txt') # => false
+  #   FileUtils.install('src0.txt', 'dest0.txt')
+  #   File.read('dest0.txt')   # => "aaa\n"
+  #
+  # If +dest+ is a file entry, copies from +src+ to +dest+, overwriting:
+  #
+  #   File.read('src1.txt')  # => "aaa\n"
+  #   File.read('dest1.txt') # => "bbb\n"
+  #   FileUtils.install('src1.txt', 'dest1.txt')
+  #   File.read('dest1.txt') # => "aaa\n"
+  #
+  # If +dest+ is a directory entry, copies from +src+ to <tt>dest/src</tt>,
+  # overwriting if necessary:
+  #
+  #   File.read('src2.txt')       # => "aaa\n"
+  #   File.read('dest2/src2.txt') # => "bbb\n"
+  #   FileUtils.install('src2.txt', 'dest2')
+  #   File.read('dest2/src2.txt') # => "aaa\n"
+  #
+  # If +src+ is an array of paths and +dest+ points to a directory,
+  # copies each path +path+ in +src+ to <tt>dest/path</tt>:
+  #
+  #   File.file?('src3.txt') # => true
+  #   File.file?('src3.dat') # => true
+  #   FileUtils.mkdir('dest3')
+  #   FileUtils.install(['src3.txt', 'src3.dat'], 'dest3')
+  #   File.file?('dest3/src3.txt') # => true
+  #   File.file?('dest3/src3.dat') # => true
+  #
+  # Keyword arguments:
+  #
+  # - <tt>group: <i>group</i></tt> - changes the group if not +nil+,
+  #   using {File.chown}[rdoc-ref:File.chown].
+  # - <tt>mode: <i>permissions</i></tt> - changes the permissions.
+  #   using {File.chmod}[rdoc-ref:File.chmod].
+  # - <tt>noop: true</tt> - does not copy entries; returns +nil+.
+  # - <tt>owner: <i>owner</i></tt> - changes the owner if not +nil+,
+  #   using {File.chown}[rdoc-ref:File.chown].
+  # - <tt>preserve: true</tt> - preserve timestamps
+  #   using {File.utime}[rdoc-ref:File.utime].
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     FileUtils.install('src0.txt', 'dest0.txt', noop: true, verbose: true)
+  #     FileUtils.install('src1.txt', 'dest1.txt', noop: true, verbose: true)
+  #     FileUtils.install('src2.txt', 'dest2', noop: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     install -c src0.txt dest0.txt
+  #     install -c src1.txt dest1.txt
+  #     install -c src2.txt dest2
+  #
+  # Related: {methods for copying}[rdoc-ref:FileUtils@Copying].
+  #
+  def install(src, dest, mode: nil, owner: nil, group: nil, preserve: nil,
+              noop: nil, verbose: nil)
+    if verbose
+      msg = +"install -c"
+      msg << ' -p' if preserve
+      msg << ' -m ' << mode_to_s(mode) if mode
+      msg << " -o #{owner}" if owner
+      msg << " -g #{group}" if group
+      msg << ' ' << [src,dest].flatten.join(' ')
+      fu_output_message msg
+    end
+    return if noop
+    uid = fu_get_uid(owner)
+    gid = fu_get_gid(group)
+    fu_each_src_dest(src, dest) do |s, d|
+      st = File.stat(s)
       unless File.exist?(d) and compare_file(s, d)
         remove_file d, true
-        copy_file s, d
-        File.utime st.atime, st.mtime, d if options[:preserve]
-        File.chmod options[:mode], d if options[:mode]
+        if d.end_with?('/')
+          mkdir_p d
+          copy_file s, d + File.basename(s)
+        else
+          mkdir_p File.expand_path('..', d)
+          copy_file s, d
+        end
+        File.utime st.atime, st.mtime, d if preserve
+        File.chmod fu_mode(mode, st), d if mode
+        File.chown uid, gid, d if uid or gid
       end
     end
   end
   module_function :install
 
-  OPT_TABLE['install'] = [:mode, :preserve, :noop, :verbose]
-
   def user_mask(target)  #:nodoc:
-    mask = 0
-    target.each_byte do |byte_chr|
-      case byte_chr.chr
-        when "u"
-          mask |= 04700
-        when "g"
-          mask |= 02070
-        when "o"
-          mask |= 01007
-        when "a"
-          mask |= 07777
+    target.each_char.inject(0) do |mask, chr|
+      case chr
+      when "u"
+        mask | 04700
+      when "g"
+        mask | 02070
+      when "o"
+        mask | 01007
+      when "a"
+        mask | 07777
+      else
+        raise ArgumentError, "invalid 'who' symbol in file mode: #{chr}"
       end
     end
-    mask
   end
   private_module_function :user_mask
 
-  def mode_mask(mode, path)  #:nodoc:
-    mask = 0
-    mode.each_byte do |byte_chr|
-      case byte_chr.chr
-        when "r"
-          mask |= 0444
-        when "w"
-          mask |= 0222
-        when "x"
-          mask |= 0111
-        when "X"
-          mask |= 0111 if FileTest::directory? path
-        when "s"
-          mask |= 06000
-        when "t"
-          mask |= 01000
-      end
+  def apply_mask(mode, user_mask, op, mode_mask)   #:nodoc:
+    case op
+    when '='
+      (mode & ~user_mask) | (user_mask & mode_mask)
+    when '+'
+      mode | (user_mask & mode_mask)
+    when '-'
+      mode & ~(user_mask & mode_mask)
     end
-    mask
   end
-  private_module_function :mode_mask
-
-  def symbolic_modes_to_i(modes, path)  #:nodoc:
-    current_mode = (File.stat(path).mode & 07777)
-    modes.split(/,/).inject(0) do |mode, mode_sym|
-      mode_sym = "a#{mode_sym}" if mode_sym =~ %r!^[+-=]!
-      target, mode = mode_sym.split %r![+-=]!
+  private_module_function :apply_mask
+
+  def symbolic_modes_to_i(mode_sym, path)  #:nodoc:
+    path = File.stat(path) unless File::Stat === path
+    mode = path.mode
+    mode_sym.split(/,/).inject(mode & 07777) do |current_mode, clause|
+      target, *actions = clause.split(/([=+-])/)
+      raise ArgumentError, "invalid file mode: #{mode_sym}" if actions.empty?
+      target = 'a' if target.empty?
       user_mask = user_mask(target)
-      mode_mask = mode_mask(mode ? mode : "", path)
-
-      case mode_sym
-        when /=/
-          current_mode &= ~(user_mask)
-          current_mode |= user_mask & mode_mask
-        when /\+/
-          current_mode |= user_mask & mode_mask
-        when /-/
-          current_mode &= ~(user_mask & mode_mask)
+      actions.each_slice(2) do |op, perm|
+        need_apply = op == '='
+        mode_mask = (perm || '').each_char.inject(0) do |mask, chr|
+          case chr
+          when "r"
+            mask | 0444
+          when "w"
+            mask | 0222
+          when "x"
+            mask | 0111
+          when "X"
+            if path.directory?
+              mask | 0111
+            else
+              mask
+            end
+          when "s"
+            mask | 06000
+          when "t"
+            mask | 01000
+          when "u", "g", "o"
+            if mask.nonzero?
+              current_mode = apply_mask(current_mode, user_mask, op, mask)
+            end
+            need_apply = false
+            copy_mask = user_mask(chr)
+            (current_mode & copy_mask) / (copy_mask & 0111) * (user_mask & 0111)
+          else
+            raise ArgumentError, "invalid 'perm' symbol in file mode: #{chr}"
+          end
+        end
+
+        if mode_mask.nonzero? || need_apply
+          current_mode = apply_mask(current_mode, user_mask, op, mode_mask)
+        end
       end
+      current_mode
     end
   end
   private_module_function :symbolic_modes_to_i
@@ -930,99 +1721,182 @@ module FileUtils
   end
   private_module_function :fu_mode
 
+  def mode_to_s(mode)  #:nodoc:
+    mode.is_a?(String) ? mode : "%o" % mode
+  end
+  private_module_function :mode_to_s
+
+  # Changes permissions on the entries at the paths given in +list+
+  # (a single path or an array of paths)
+  # to the permissions given by +mode+;
+  # returns +list+ if it is an array, <tt>[list]</tt> otherwise:
   #
-  # Options: noop verbose
+  # - Modifies each entry that is a regular file using
+  #   {File.chmod}[rdoc-ref:File.chmod].
+  # - Modifies each entry that is a symbolic link using
+  #   {File.lchmod}[rdoc-ref:File.lchmod].
   #
-  # Changes permission bits on the named files (in +list+) to the bit pattern
-  # represented by +mode+.
+  # Argument +list+ or its elements
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
   #
-  # +mode+ is the symbolic and absolute mode can be used.
+  # Argument +mode+ may be either an integer or a string:
   #
-  # Absolute mode is
-  #   FileUtils.chmod 0755, 'somecommand'
-  #   FileUtils.chmod 0644, %w(my.rb your.rb his.rb her.rb)
-  #   FileUtils.chmod 0755, '/usr/bin/ruby', :verbose => true
+  # - \Integer +mode+: represents the permission bits to be set:
   #
-  # Symbolic mode is
-  #   FileUtils.chmod "u=wrx,go=rx", 'somecommand'
-  #   FileUtils.chmod "u=wr,go=rr", %w(my.rb your.rb his.rb her.rb)
-  #   FileUtils.chmod "u=wrx,go=rx", '/usr/bin/ruby', :verbose => true
+  #     FileUtils.chmod(0755, 'src0.txt')
+  #     FileUtils.chmod(0644, ['src0.txt', 'src0.dat'])
   #
-  #   "a" is user, group, other mask.
-  #   "u" is user's mask.
-  #   "g" is group's mask.
-  #   "o" is other's mask.
-  #   "w" is write permission.
-  #   "r" is read permission.
-  #   "x" is execute permission.
-  #   "s" is uid, gid.
-  #   "t" is sticky bit.
-  #   "+" is added to a class given the specified mode.
-  #   "-" Is removed from a given class given mode.
-  #   "=" Is the exact nature of the class will be given a specified mode.
-
-  def chmod(mode, list, options = {})
-    fu_check_options options, OPT_TABLE['chmod']
+  # - \String +mode+: represents the permissions to be set:
+  #
+  #   The string is of the form <tt>[targets][[operator][perms[,perms]]</tt>, where:
+  #
+  #   - +targets+ may be any combination of these letters:
+  #
+  #     - <tt>'u'</tt>: permissions apply to the file's owner.
+  #     - <tt>'g'</tt>: permissions apply to users in the file's group.
+  #     - <tt>'o'</tt>: permissions apply to other users not in the file's group.
+  #     - <tt>'a'</tt> (the default): permissions apply to all users.
+  #
+  #   - +operator+ may be one of these letters:
+  #
+  #     - <tt>'+'</tt>: adds permissions.
+  #     - <tt>'-'</tt>: removes permissions.
+  #     - <tt>'='</tt>: sets (replaces) permissions.
+  #
+  #   - +perms+ (may be repeated, with separating commas)
+  #     may be any combination of these letters:
+  #
+  #     - <tt>'r'</tt>: Read.
+  #     - <tt>'w'</tt>: Write.
+  #     - <tt>'x'</tt>: Execute (search, for a directory).
+  #     - <tt>'X'</tt>: Search (for a directories only;
+  #       must be used with <tt>'+'</tt>)
+  #     - <tt>'s'</tt>: Uid or gid.
+  #     - <tt>'t'</tt>: Sticky bit.
+  #
+  #   Examples:
+  #
+  #     FileUtils.chmod('u=wrx,go=rx', 'src1.txt')
+  #     FileUtils.chmod('u=wrx,go=rx', '/usr/bin/ruby')
+  #
+  # Keyword arguments:
+  #
+  # - <tt>noop: true</tt> - does not change permissions; returns +nil+.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     FileUtils.chmod(0755, 'src0.txt', noop: true, verbose: true)
+  #     FileUtils.chmod(0644, ['src0.txt', 'src0.dat'], noop: true, verbose: true)
+  #     FileUtils.chmod('u=wrx,go=rx', 'src1.txt', noop: true, verbose: true)
+  #     FileUtils.chmod('u=wrx,go=rx', '/usr/bin/ruby', noop: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     chmod 755 src0.txt
+  #     chmod 644 src0.txt src0.dat
+  #     chmod u=wrx,go=rx src1.txt
+  #     chmod u=wrx,go=rx /usr/bin/ruby
+  #
+  # Related: FileUtils.chmod_R.
+  #
+  def chmod(mode, list, noop: nil, verbose: nil)
     list = fu_list(list)
-    fu_output_message sprintf('chmod %o %s', mode, list.join(' ')) if options[:verbose]
-    return if options[:noop]
+    fu_output_message sprintf('chmod %s %s', mode_to_s(mode), list.join(' ')) if verbose
+    return if noop
     list.each do |path|
       Entry_.new(path).chmod(fu_mode(mode, path))
     end
   end
   module_function :chmod
 
-  OPT_TABLE['chmod'] = [:noop, :verbose]
-
+  # Like FileUtils.chmod, but changes permissions recursively.
   #
-  # Options: noop verbose force
-  #
-  # Changes permission bits on the named files (in +list+)
-  # to the bit pattern represented by +mode+.
-  #
-  #   FileUtils.chmod_R 0700, "/tmp/app.#{$$}"
-  #   FileUtils.chmod_R "u=wrx", "/tmp/app.#{$$}"
-  #
-  def chmod_R(mode, list, options = {})
-    fu_check_options options, OPT_TABLE['chmod_R']
+  def chmod_R(mode, list, noop: nil, verbose: nil, force: nil)
     list = fu_list(list)
-    fu_output_message sprintf('chmod -R%s %o %s',
-                              (options[:force] ? 'f' : ''),
-                              mode, list.join(' ')) if options[:verbose]
-    return if options[:noop]
+    fu_output_message sprintf('chmod -R%s %s %s',
+                              (force ? 'f' : ''),
+                              mode_to_s(mode), list.join(' ')) if verbose
+    return if noop
     list.each do |root|
       Entry_.new(root).traverse do |ent|
         begin
           ent.chmod(fu_mode(mode, ent.path))
         rescue
-          raise unless options[:force]
+          raise unless force
         end
       end
     end
   end
   module_function :chmod_R
 
-  OPT_TABLE['chmod_R'] = [:noop, :verbose, :force]
-
+  # Changes the owner and group on the entries at the paths given in +list+
+  # (a single path or an array of paths)
+  # to the given +user+ and +group+;
+  # returns +list+ if it is an array, <tt>[list]</tt> otherwise:
+  #
+  # - Modifies each entry that is a regular file using
+  #   {File.chown}[rdoc-ref:File.chown].
+  # - Modifies each entry that is a symbolic link using
+  #   {File.lchown}[rdoc-ref:File.lchown].
+  #
+  # Argument +list+ or its elements
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
+  #
+  # User and group:
+  #
+  # - Argument +user+ may be a user name or a user id;
+  #   if +nil+ or +-1+, the user is not changed.
+  # - Argument +group+ may be a group name or a group id;
+  #   if +nil+ or +-1+, the group is not changed.
+  # - The user must be a member of the group.
+  #
+  # Examples:
+  #
+  #   # One path.
+  #   # User and group as string names.
+  #   File.stat('src0.txt').uid # => 1004
+  #   File.stat('src0.txt').gid # => 1004
+  #   FileUtils.chown('user2', 'group1', 'src0.txt')
+  #   File.stat('src0.txt').uid # => 1006
+  #   File.stat('src0.txt').gid # => 1005
+  #
+  #   # User and group as uid and gid.
+  #   FileUtils.chown(1004, 1004, 'src0.txt')
+  #   File.stat('src0.txt').uid # => 1004
+  #   File.stat('src0.txt').gid # => 1004
+  #
+  #   # Array of paths.
+  #   FileUtils.chown(1006, 1005, ['src0.txt', 'src0.dat'])
   #
-  # Options: noop verbose
+  #   # Directory (not recursive).
+  #   FileUtils.chown('user2', 'group1', '.')
   #
-  # Changes owner and group on the named files (in +list+)
-  # to the user +user+ and the group +group+.  +user+ and +group+
-  # may be an ID (Integer/String) or a name (String).
-  # If +user+ or +group+ is nil, this method does not change
-  # the attribute.
+  # Keyword arguments:
   #
-  #   FileUtils.chown 'root', 'staff', '/usr/local/bin/ruby'
-  #   FileUtils.chown nil, 'bin', Dir.glob('/usr/bin/*'), :verbose => true
+  # - <tt>noop: true</tt> - does not change permissions; returns +nil+.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
   #
-  def chown(user, group, list, options = {})
-    fu_check_options options, OPT_TABLE['chown']
+  #     FileUtils.chown('user2', 'group1', 'src0.txt', noop: true, verbose: true)
+  #     FileUtils.chown(1004, 1004, 'src0.txt', noop: true, verbose: true)
+  #     FileUtils.chown(1006, 1005, ['src0.txt', 'src0.dat'], noop: true, verbose: true)
+  #     FileUtils.chown('user2', 'group1', path, noop: true, verbose: true)
+  #     FileUtils.chown('user2', 'group1', '.', noop: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     chown user2:group1 src0.txt
+  #     chown 1004:1004 src0.txt
+  #     chown 1006:1005 src0.txt src0.dat
+  #     chown user2:group1 src0.txt
+  #     chown user2:group1 .
+  #
+  # Related: FileUtils.chown_R.
+  #
+  def chown(user, group, list, noop: nil, verbose: nil)
     list = fu_list(list)
-    fu_output_message sprintf('chown %s%s',
-                              [user,group].compact.join(':') + ' ',
-                              list.join(' ')) if options[:verbose]
-    return if options[:noop]
+    fu_output_message sprintf('chown %s %s',
+                              (group ? "#{user}:#{group}" : user || ':'),
+                              list.join(' ')) if verbose
+    return if noop
     uid = fu_get_uid(user)
     gid = fu_get_gid(group)
     list.each do |path|
@@ -1031,106 +1905,109 @@ module FileUtils
   end
   module_function :chown
 
-  OPT_TABLE['chown'] = [:noop, :verbose]
-
-  #
-  # Options: noop verbose force
+  # Like FileUtils.chown, but changes owner and group recursively.
   #
-  # Changes owner and group on the named files (in +list+)
-  # to the user +user+ and the group +group+ recursively.
-  # +user+ and +group+ may be an ID (Integer/String) or
-  # a name (String).  If +user+ or +group+ is nil, this
-  # method does not change the attribute.
-  #
-  #   FileUtils.chown_R 'www', 'www', '/var/www/htdocs'
-  #   FileUtils.chown_R 'cvs', 'cvs', '/var/cvs', :verbose => true
-  #
-  def chown_R(user, group, list, options = {})
-    fu_check_options options, OPT_TABLE['chown_R']
+  def chown_R(user, group, list, noop: nil, verbose: nil, force: nil)
     list = fu_list(list)
-    fu_output_message sprintf('chown -R%s %s%s',
-                              (options[:force] ? 'f' : ''),
-                              [user,group].compact.join(':') + ' ',
-                              list.join(' ')) if options[:verbose]
-    return if options[:noop]
+    fu_output_message sprintf('chown -R%s %s %s',
+                              (force ? 'f' : ''),
+                              (group ? "#{user}:#{group}" : user || ':'),
+                              list.join(' ')) if verbose
+    return if noop
     uid = fu_get_uid(user)
     gid = fu_get_gid(group)
-    return unless uid or gid
     list.each do |root|
       Entry_.new(root).traverse do |ent|
         begin
           ent.chown uid, gid
         rescue
-          raise unless options[:force]
+          raise unless force
         end
       end
     end
   end
   module_function :chown_R
 
-  OPT_TABLE['chown_R'] = [:noop, :verbose, :force]
-
-  begin
-    require 'etc'
-
-    def fu_get_uid(user)   #:nodoc:
-      return nil unless user
-      case user
-      when Integer
-        user
-      when /\A\d+\z/
-        user.to_i
-      else
-        Etc.getpwnam(user).uid
-      end
-    end
-    private_module_function :fu_get_uid
-
-    def fu_get_gid(group)   #:nodoc:
-      return nil unless group
-      case group
-      when Integer
-        group
-      when /\A\d+\z/
-        group.to_i
-      else
-        Etc.getgrnam(group).gid
-      end
-    end
-    private_module_function :fu_get_gid
-
-  rescue LoadError
-    # need Win32 support???
-
-    def fu_get_uid(user)   #:nodoc:
-      user    # FIXME
+  def fu_get_uid(user)   #:nodoc:
+    return nil unless user
+    case user
+    when Integer
+      user
+    when /\A\d+\z/
+      user.to_i
+    else
+      require 'etc'
+      Etc.getpwnam(user) ? Etc.getpwnam(user).uid : nil
     end
-    private_module_function :fu_get_uid
-
-    def fu_get_gid(group)   #:nodoc:
-      group   # FIXME
+  end
+  private_module_function :fu_get_uid
+
+  def fu_get_gid(group)   #:nodoc:
+    return nil unless group
+    case group
+    when Integer
+      group
+    when /\A\d+\z/
+      group.to_i
+    else
+      require 'etc'
+      Etc.getgrnam(group) ? Etc.getgrnam(group).gid : nil
     end
-    private_module_function :fu_get_gid
   end
+  private_module_function :fu_get_gid
 
+  # Updates modification times (mtime) and access times (atime)
+  # of the entries given by the paths in +list+
+  # (a single path or an array of paths);
+  # returns +list+ if it is an array, <tt>[list]</tt> otherwise.
   #
-  # Options: noop verbose
+  # By default, creates an empty file for any path to a non-existent entry;
+  # use keyword argument +nocreate+ to raise an exception instead.
   #
-  # Updates modification time (mtime) and access time (atime) of file(s) in
-  # +list+.  Files are created if they don't exist.
+  # Argument +list+ or its elements
+  # should be {interpretable as paths}[rdoc-ref:FileUtils@Path+Arguments].
   #
-  #   FileUtils.touch 'timestamp'
-  #   FileUtils.touch Dir.glob('*.c');  system 'make'
+  # Examples:
   #
-  def touch(list, options = {})
-    fu_check_options options, OPT_TABLE['touch']
+  #   # Single path.
+  #   f = File.new('src0.txt') # Existing file.
+  #   f.atime # => 2022-06-10 11:11:21.200277 -0700
+  #   f.mtime # => 2022-06-10 11:11:21.200277 -0700
+  #   FileUtils.touch('src0.txt')
+  #   f = File.new('src0.txt')
+  #   f.atime # => 2022-06-11 08:28:09.8185343 -0700
+  #   f.mtime # => 2022-06-11 08:28:09.8185343 -0700
+  #
+  #   # Array of paths.
+  #   FileUtils.touch(['src0.txt', 'src0.dat'])
+  #
+  # Keyword arguments:
+  #
+  # - <tt>mtime: <i>time</i></tt> - sets the entry's mtime to the given time,
+  #   instead of the current time.
+  # - <tt>nocreate: true</tt> - raises an exception if the entry does not exist.
+  # - <tt>noop: true</tt> - does not touch entries; returns +nil+.
+  # - <tt>verbose: true</tt> - prints an equivalent command:
+  #
+  #     FileUtils.touch('src0.txt', noop: true, verbose: true)
+  #     FileUtils.touch(['src0.txt', 'src0.dat'], noop: true, verbose: true)
+  #     FileUtils.touch(path, noop: true, verbose: true)
+  #
+  #   Output:
+  #
+  #     touch src0.txt
+  #     touch src0.txt src0.dat
+  #     touch src0.txt
+  #
+  # Related: FileUtils.uptodate?.
+  #
+  def touch(list, noop: nil, verbose: nil, mtime: nil, nocreate: nil)
     list = fu_list(list)
-    created = nocreate = options[:nocreate]
-    t = options[:mtime]
-    if options[:verbose]
+    t = mtime
+    if verbose
       fu_output_message "touch #{nocreate ? '-c ' : ''}#{t ? t.strftime('-t %Y%m%d%H%M.%S ') : ''}#{list.join ' '}"
     end
-    return if options[:noop]
+    return if noop
     list.each do |path|
       created = nocreate
       begin
@@ -1147,22 +2024,24 @@ module FileUtils
   end
   module_function :touch
 
-  OPT_TABLE['touch'] = [:noop, :verbose, :mtime, :nocreate]
-
   private
 
-  module StreamUtils_
+  module StreamUtils_ # :nodoc:
+
     private
 
-    def fu_windows?
-      /mswin|mingw|bccwin|emx/ =~ RUBY_PLATFORM
+    case (defined?(::RbConfig) ? ::RbConfig::CONFIG['host_os'] : ::RUBY_PLATFORM)
+    when /mswin|mingw/
+      def fu_windows?; true end #:nodoc:
+    else
+      def fu_windows?; false end #:nodoc:
     end
 
     def fu_copy_stream0(src, dest, blksize = nil)   #:nodoc:
       IO.copy_stream(src, dest)
     end
 
-    def fu_stream_blksize(*streams)
+    def fu_stream_blksize(*streams) #:nodoc:
       streams.each do |s|
         next unless s.respond_to?(:stat)
         size = fu_blksize(s.stat)
@@ -1171,14 +2050,14 @@ module FileUtils
       fu_default_blksize()
     end
 
-    def fu_blksize(st)
+    def fu_blksize(st) #:nodoc:
       s = st.blksize
       return nil unless s
       return nil if s == 0
       s
     end
 
-    def fu_default_blksize
+    def fu_default_blksize #:nodoc:
       1024
     end
   end
@@ -1227,7 +2106,12 @@ module FileUtils
     end
 
     def exist?
-      lstat! ? true : false
+      begin
+        lstat
+        true
+      rescue Errno::ENOENT
+        false
+      end
     end
 
     def file?
@@ -1274,10 +2158,12 @@ module FileUtils
 
     def entries
       opts = {}
-      opts[:encoding] = ::Encoding::UTF_8 if fu_windows?
-      Dir.entries(path(), opts)\
-          .reject {|n| n == '.' or n == '..' }\
-          .map {|n| Entry_.new(prefix(), join(rel(), n.untaint)) }
+      opts[:encoding] = fu_windows? ? ::Encoding::UTF_8 : path.encoding
+
+      files = Dir.children(path, **opts)
+
+      untaint = RUBY_VERSION < '2.7'
+      files.map {|n| Entry_.new(prefix(), join(rel(), untaint ? n.untaint : n)) }
     end
 
     def stat
@@ -1322,6 +2208,7 @@ module FileUtils
       else
         File.chmod mode, path()
       end
+    rescue Errno::EOPNOTSUPP
     end
 
     def chown(uid, gid)
@@ -1332,12 +2219,29 @@ module FileUtils
       end
     end
 
+    def link(dest)
+      case
+      when directory?
+        if !File.exist?(dest) and descendant_directory?(dest, path)
+          raise ArgumentError, "cannot link directory %s to itself %s" % [path, dest]
+        end
+        begin
+          Dir.mkdir dest
+        rescue
+          raise unless File.directory?(dest)
+        end
+      else
+        File.link path(), dest
+      end
+    end
+
     def copy(dest)
+      lstat
       case
       when file?
         copy_file dest
       when directory?
-        if !File.exist?(dest) and descendant_diretory?(dest, path)
+        if !File.exist?(dest) and descendant_directory?(dest, path)
           raise ArgumentError, "cannot copy directory %s to itself %s" % [path, dest]
         end
         begin
@@ -1347,18 +2251,21 @@ module FileUtils
         end
       when symlink?
         File.symlink File.readlink(path()), dest
-      when chardev?
-        raise "cannot handle device file" unless File.respond_to?(:mknod)
-        mknod dest, ?c, 0666, lstat().rdev
-      when blockdev?
-        raise "cannot handle device file" unless File.respond_to?(:mknod)
-        mknod dest, ?b, 0666, lstat().rdev
+      when chardev?, blockdev?
+        raise "cannot handle device file"
       when socket?
-        raise "cannot handle socket" unless File.respond_to?(:mknod)
-        mknod dest, nil, lstat().mode, 0
+        begin
+          require 'socket'
+        rescue LoadError
+          raise "cannot handle socket"
+        else
+          raise "cannot handle socket" unless defined?(UNIXServer)
+        end
+        UNIXServer.new(dest).close
+        File.chmod lstat().mode, dest
       when pipe?
         raise "cannot handle FIFO" unless File.respond_to?(:mkfifo)
-        mkfifo dest, 0666
+        File.mkfifo dest, lstat().mode
       when door?
         raise "cannot handle door: #{path()}"
       else
@@ -1376,14 +2283,30 @@ module FileUtils
 
     def copy_metadata(path)
       st = lstat()
-      File.utime st.atime, st.mtime, path
+      if !st.symlink?
+        File.utime st.atime, st.mtime, path
+      end
+      mode = st.mode
       begin
-        File.chown st.uid, st.gid, path
-      rescue Errno::EPERM
+        if st.symlink?
+          begin
+            File.lchown st.uid, st.gid, path
+          rescue NotImplementedError
+          end
+        else
+          File.chown st.uid, st.gid, path
+        end
+      rescue Errno::EPERM, Errno::EACCES
         # clear setuid/setgid
-        File.chmod st.mode & 01777, path
+        mode &= 01777
+      end
+      if st.symlink?
+        begin
+          File.lchmod mode, path
+        rescue NotImplementedError, Errno::EOPNOTSUPP
+        end
       else
-        File.chmod st.mode, path
+        File.chmod mode, path
       end
     end
 
@@ -1439,7 +2362,16 @@ module FileUtils
 
     def postorder_traverse
       if directory?
-        entries().each do |ent|
+        begin
+          children = entries()
+        rescue Errno::EACCES
+          # Failed to get the list of children.
+          # Assuming there is no children, try to process the parent directory.
+          yield self
+          return
+        end
+
+        children.each do |ent|
           ent.postorder_traverse do |e|
             yield e
           end
@@ -1448,16 +2380,26 @@ module FileUtils
       yield self
     end
 
+    def wrap_traverse(pre, post)
+      pre.call self
+      if directory?
+        entries.each do |ent|
+          ent.wrap_traverse pre, post
+        end
+      end
+      post.call self
+    end
+
     private
 
-    $fileutils_rb_have_lchmod = nil
+    @@fileutils_rb_have_lchmod = nil
 
     def have_lchmod?
       # This is not MT-safe, but it does not matter.
-      if $fileutils_rb_have_lchmod == nil
-        $fileutils_rb_have_lchmod = check_have_lchmod?
+      if @@fileutils_rb_have_lchmod == nil
+        @@fileutils_rb_have_lchmod = check_have_lchmod?
       end
-      $fileutils_rb_have_lchmod
+      @@fileutils_rb_have_lchmod
     end
 
     def check_have_lchmod?
@@ -1468,14 +2410,14 @@ module FileUtils
       return false
     end
 
-    $fileutils_rb_have_lchown = nil
+    @@fileutils_rb_have_lchown = nil
 
     def have_lchown?
       # This is not MT-safe, but it does not matter.
-      if $fileutils_rb_have_lchown == nil
-        $fileutils_rb_have_lchown = check_have_lchown?
+      if @@fileutils_rb_have_lchown == nil
+        @@fileutils_rb_have_lchown = check_have_lchown?
       end
-      $fileutils_rb_have_lchown
+      @@fileutils_rb_have_lchown
     end
 
     def check_have_lchown?
@@ -1489,18 +2431,29 @@ module FileUtils
     def join(dir, base)
       return File.path(dir) if not base or base == '.'
       return File.path(base) if not dir or dir == '.'
-      File.join(dir, base)
+      begin
+        File.join(dir, base)
+      rescue EncodingError
+        if fu_windows?
+          File.join(dir.encode(::Encoding::UTF_8), base.encode(::Encoding::UTF_8))
+        else
+          raise
+        end
+      end
     end
 
     if File::ALT_SEPARATOR
-      DIRECTORY_TERM = "(?=[/#{Regexp.quote(File::ALT_SEPARATOR)}]|\\z)".freeze
+      DIRECTORY_TERM = "(?=[/#{Regexp.quote(File::ALT_SEPARATOR)}]|\\z)"
     else
-      DIRECTORY_TERM = "(?=/|\\z)".freeze
+      DIRECTORY_TERM = "(?=/|\\z)"
     end
-    SYSCASE = File::FNM_SYSCASE.nonzero? ? "-i" : ""
 
-    def descendant_diretory?(descendant, ascendant)
-      /\A(?#{SYSCASE}:#{Regexp.quote(ascendant)})#{DIRECTORY_TERM}/ =~ File.dirname(descendant)
+    def descendant_directory?(descendant, ascendant)
+      if File::FNM_SYSCASE.nonzero?
+        File.expand_path(File.dirname(descendant)).casecmp(File.expand_path(ascendant)) == 0
+      else
+        File.expand_path(File.dirname(descendant)) == File.expand_path(ascendant)
+      end
     end
   end   # class Entry_
 
@@ -1512,20 +2465,24 @@ module FileUtils
   def fu_each_src_dest(src, dest)   #:nodoc:
     fu_each_src_dest0(src, dest) do |s, d|
       raise ArgumentError, "same file: #{s} and #{d}" if fu_same?(s, d)
-      yield s, d, File.stat(s)
+      yield s, d
     end
   end
   private_module_function :fu_each_src_dest
 
-  def fu_each_src_dest0(src, dest)   #:nodoc:
+  def fu_each_src_dest0(src, dest, target_directory = true)   #:nodoc:
     if tmp = Array.try_convert(src)
+      unless target_directory or tmp.size <= 1
+        tmp = tmp.map {|f| File.path(f)} # A workaround for RBS
+        raise ArgumentError, "extra target #{tmp}"
+      end
       tmp.each do |s|
         s = File.path(s)
-        yield s, File.join(dest, File.basename(s))
+        yield s, (target_directory ? File.join(dest, File.basename(s)) : dest)
       end
     else
       src = File.path(src)
-      if File.directory?(dest)
+      if target_directory and File.directory?(dest)
         yield src, File.join(dest, File.basename(src))
       else
         yield src, File.path(dest)
@@ -1539,90 +2496,137 @@ module FileUtils
   end
   private_module_function :fu_same?
 
-  def fu_check_options(options, optdecl)   #:nodoc:
-    h = options.dup
-    optdecl.each do |opt|
-      h.delete opt
+  def fu_output_message(msg)   #:nodoc:
+    output = @fileutils_output if defined?(@fileutils_output)
+    output ||= $stdout
+    if defined?(@fileutils_label)
+      msg = @fileutils_label + msg
     end
-    raise ArgumentError, "no such option: #{h.keys.join(' ')}" unless h.empty?
+    output.puts msg
   end
-  private_module_function :fu_check_options
+  private_module_function :fu_output_message
 
-  def fu_update_option(args, new)   #:nodoc:
-    if tmp = Hash.try_convert(args.last)
-      args[-1] = tmp.dup.update(new)
-    else
-      args.push new
+  def fu_split_path(path) #:nodoc:
+    path = File.path(path)
+    list = []
+    until (parent, base = File.split(path); parent == path or parent == ".")
+      if base != '..' and list.last == '..' and !(fu_have_symlink? && File.symlink?(path))
+        list.pop
+      else
+        list << base
+      end
+      path = parent
     end
-    args
+    list << path
+    list.reverse!
   end
-  private_module_function :fu_update_option
+  private_module_function :fu_split_path
 
-  @fileutils_output = $stderr
-  @fileutils_label  = ''
+  def fu_common_components(target, base) #:nodoc:
+    i = 0
+    while target[i]&.== base[i]
+      i += 1
+    end
+    i
+  end
+  private_module_function :fu_common_components
+
+  def fu_clean_components(*comp) #:nodoc:
+    comp.shift while comp.first == "."
+    return comp if comp.empty?
+    clean = [comp.shift]
+    path = File.join(*clean, "") # ending with File::SEPARATOR
+    while c = comp.shift
+      if c == ".." and clean.last != ".." and !(fu_have_symlink? && File.symlink?(path))
+        clean.pop
+        path.sub!(%r((?<=\A|/)[^/]+/\z), "")
+      else
+        clean << c
+        path << c << "/"
+      end
+    end
+    clean
+  end
+  private_module_function :fu_clean_components
 
-  def fu_output_message(msg)   #:nodoc:
-    @fileutils_output ||= $stderr
-    @fileutils_label  ||= ''
-    @fileutils_output.puts @fileutils_label + msg
+  if fu_windows?
+    def fu_starting_path?(path) #:nodoc:
+      path&.start_with?(%r(\w:|/))
+    end
+  else
+    def fu_starting_path?(path) #:nodoc:
+      path&.start_with?("/")
+    end
   end
-  private_module_function :fu_output_message
+  private_module_function :fu_starting_path?
 
+  # This hash table holds command options.
+  OPT_TABLE = {}    #:nodoc: internal use only
+  (private_instance_methods & methods(false)).inject(OPT_TABLE) {|tbl, name|
+    (tbl[name.to_s] = instance_method(name).parameters).map! {|t, n| n if t == :key}.compact!
+    tbl
+  }
+
+  public
+
+  # Returns an array of the string names of \FileUtils methods
+  # that accept one or more keyword arguments:
   #
-  # Returns an Array of method names which have any options.
-  #
-  #   p FileUtils.commands  #=> ["chmod", "cp", "cp_r", "install", ...]
+  #   FileUtils.commands.sort.take(3) # => ["cd", "chdir", "chmod"]
   #
-  def FileUtils.commands
+  def self.commands
     OPT_TABLE.keys
   end
 
+  # Returns an array of the string keyword names:
   #
-  # Returns an Array of option names.
-  #
-  #   p FileUtils.options  #=> ["noop", "force", "verbose", "preserve", "mode"]
+  #   FileUtils.options.take(3) # => ["noop", "verbose", "force"]
   #
-  def FileUtils.options
+  def self.options
     OPT_TABLE.values.flatten.uniq.map {|sym| sym.to_s }
   end
 
+  # Returns +true+ if method +mid+ accepts the given option +opt+, +false+ otherwise;
+  # the arguments may be strings or symbols:
   #
-  # Returns true if the method +mid+ have an option +opt+.
-  #
-  #   p FileUtils.have_option?(:cp, :noop)     #=> true
-  #   p FileUtils.have_option?(:rm, :force)    #=> true
-  #   p FileUtils.have_option?(:rm, :perserve) #=> false
+  #   FileUtils.have_option?(:chmod, :noop) # => true
+  #   FileUtils.have_option?('chmod', 'secure') # => false
   #
-  def FileUtils.have_option?(mid, opt)
+  def self.have_option?(mid, opt)
     li = OPT_TABLE[mid.to_s] or raise ArgumentError, "no such method: #{mid}"
     li.include?(opt)
   end
 
+  # Returns an array of the string keyword name for method +mid+;
+  # the argument may be a string or a symbol:
   #
-  # Returns an Array of option names of the method +mid+.
+  #   FileUtils.options_of(:rm) # => ["force", "noop", "verbose"]
+  #   FileUtils.options_of('mv') # => ["force", "noop", "verbose", "secure"]
   #
-  #   p FileUtils.options(:rm)  #=> ["noop", "verbose", "force"]
-  #
-  def FileUtils.options_of(mid)
+  def self.options_of(mid)
     OPT_TABLE[mid.to_s].map {|sym| sym.to_s }
   end
 
+  # Returns an array of the string method names of the methods
+  # that accept the given keyword option +opt+;
+  # the argument must be a symbol:
   #
-  # Returns an Array of method names which have the option +opt+.
-  #
-  #   p FileUtils.collect_method(:preserve) #=> ["cp", "cp_r", "copy", "install"]
+  #   FileUtils.collect_method(:preserve) # => ["cp", "copy", "cp_r", "install"]
   #
-  def FileUtils.collect_method(opt)
+  def self.collect_method(opt)
     OPT_TABLE.keys.select {|m| OPT_TABLE[m].include?(opt) }
   end
 
-  LOW_METHODS = singleton_methods(false) - collect_method(:noop).map(&:intern)
-  module LowMethods
-    module_eval("private\n" + ::FileUtils::LOW_METHODS.map {|name| "def #{name}(*)end"}.join("\n"),
-                __FILE__, __LINE__)
+  private
+
+  LOW_METHODS = singleton_methods(false) - collect_method(:noop).map(&:intern) # :nodoc:
+  module LowMethods # :nodoc: internal use only
+    private
+    def _do_nothing(*)end
+    ::FileUtils::LOW_METHODS.map {|name| alias_method name, :_do_nothing}
   end
 
-  METHODS = singleton_methods() - [:private_module_function,
+  METHODS = singleton_methods() - [:private_module_function,                  # :nodoc:
       :commands, :options, :have_option?, :options_of, :collect_method]
 
   #
@@ -1632,21 +2636,18 @@ module FileUtils
   #
   module Verbose
     include FileUtils
-    @fileutils_output  = $stderr
-    @fileutils_label   = ''
-    ::FileUtils.collect_method(:verbose).each do |name|
+    names = ::FileUtils.collect_method(:verbose)
+    names.each do |name|
       module_eval(<<-EOS, __FILE__, __LINE__ + 1)
-        def #{name}(*args)
-          super(*fu_update_option(args, :verbose => true))
+        def #{name}(*args, **options)
+          super(*args, **options, verbose: true)
         end
-        private :#{name}
       EOS
     end
+    private(*names)
     extend self
     class << self
-      ::FileUtils::METHODS.each do |m|
-        public m
-      end
+      public(*::FileUtils::METHODS)
     end
   end
 
@@ -1658,21 +2659,18 @@ module FileUtils
   module NoWrite
     include FileUtils
     include LowMethods
-    @fileutils_output  = $stderr
-    @fileutils_label   = ''
-    ::FileUtils.collect_method(:noop).each do |name|
+    names = ::FileUtils.collect_method(:noop)
+    names.each do |name|
       module_eval(<<-EOS, __FILE__, __LINE__ + 1)
-        def #{name}(*args)
-          super(*fu_update_option(args, :noop => true))
+        def #{name}(*args, **options)
+          super(*args, **options, noop: true)
         end
-        private :#{name}
       EOS
     end
+    private(*names)
     extend self
     class << self
-      ::FileUtils::METHODS.each do |m|
-        public m
-      end
+      public(*::FileUtils::METHODS)
     end
   end
 
@@ -1685,21 +2683,18 @@ module FileUtils
   module DryRun
     include FileUtils
     include LowMethods
-    @fileutils_output  = $stderr
-    @fileutils_label   = ''
-    ::FileUtils.collect_method(:noop).each do |name|
+    names = ::FileUtils.collect_method(:noop)
+    names.each do |name|
       module_eval(<<-EOS, __FILE__, __LINE__ + 1)
-        def #{name}(*args)
-          super(*fu_update_option(args, :noop => true, :verbose => true))
+        def #{name}(*args, **options)
+          super(*args, **options, noop: true, verbose: true)
         end
-        private :#{name}
       EOS
     end
+    private(*names)
     extend self
     class << self
-      ::FileUtils::METHODS.each do |m|
-        public m
-      end
+      public(*::FileUtils::METHODS)
     end
   end
 
diff --git a/lib/find.gemspec b/lib/find.gemspec
new file mode 100644
index 0000000000..aef24a5028
--- /dev/null
+++ b/lib/find.gemspec
@@ -0,0 +1,29 @@
+name = File.basename(__FILE__, ".gemspec")
+version = ["lib", Array.new(name.count("-")+1).join("/")].find do |dir|
+  break File.foreach(File.join(__dir__, dir, "#{name.tr('-', '/')}.rb")) do |line|
+    /^\s*VERSION\s*=\s*"(.*)"/ =~ line and break $1
+  end rescue nil
+end
+
+Gem::Specification.new do |spec|
+  spec.name          = name
+  spec.version       = version
+  spec.authors       = ['Kazuki Tsujimoto']
+  spec.email         = ['kazuki@callcc.net']
+
+  spec.summary       = %q{This module supports top-down traversal of a set of file paths.}
+  spec.description   = %q{This module supports top-down traversal of a set of file paths.}
+  spec.homepage      = "https://github.com/ruby/find"
+  spec.required_ruby_version = Gem::Requirement.new(">= 2.3.0")
+  spec.licenses      = ["Ruby", "BSD-2-Clause"]
+
+  spec.metadata["homepage_uri"] = spec.homepage
+  spec.metadata["source_code_uri"] = spec.homepage
+
+  # Specify which files should be added to the gem when it is released.
+  # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
+  spec.files         = Dir.chdir(File.expand_path('..', __FILE__)) do
+    `git ls-files -z`.split("\x0").reject { |f| f.match(%r{^(test|spec|features)/}) }
+  end
+  spec.require_paths = ["lib"]
+end
diff --git a/lib/find.rb b/lib/find.rb
index cd2d1bf38b..d9b81eb92d 100644
--- a/lib/find.rb
+++ b/lib/find.rb
@@ -1,73 +1,109 @@
+# frozen_string_literal: true
 #
 # find.rb: the Find module for processing all files under a given directory.
 #
 
+# :markup: markdown
 #
-# The +Find+ module supports the top-down traversal of a set of file paths.
-#
-# For example, to total the size of all files under your home directory,
-# ignoring anything in a "dot" directory (e.g. $HOME/.ssh):
-#
-#   require 'find'
-#
-#   total_size = 0
-#
-#   Find.find(ENV["HOME"]) do |path|
-#     if FileTest.directory?(path)
-#       if File.basename(path)[0] == ?.
-#         Find.prune       # Don't look any further into this directory.
-#       else
-#         next
-#       end
-#     else
-#       total_size += FileTest.size(path)
-#     end
-#   end
-#
+# \Module \Find supports the top-down traversal of entries in the file system.
 module Find
 
+  # The version string
+  VERSION = "0.2.0"
+
+  # :markup: markdown
+  #
+  # With a block given, performs a depth-first traversal of each given path in `paths`;
+  # calls the block with each found file or directory path:
+  #
+  # ```ruby
+  # paths = []
+  # Find.find('bin', 'jit') {|path| paths << path }
+  # paths
+  # # =>
+  # # ["bin",
+  # #  "bin/gem",
+  # #  "jit",
+  # #  "jit/Cargo.toml",
+  # #  "jit/src",
+  # #  "jit/src/lib.rs"]
+  # ```
   #
-  # Calls the associated block with the name of every file and directory listed
-  # as arguments, then recursively on their subdirectories, and so on.
+  # Raises an exception if a given path cannot be read.
   #
-  # See the +Find+ module documentation for an example.
+  # When keyword argument `ignore_error` is given as `true` (the default),
+  # certain exceptions during traversal are ignored (i.e., silently rescued):
+  # Errno::ENOENT, Errno::EACCES, Errno::ENOTDIR, Errno::ELOOP, Errno::ENAMETOOLONG, Errno::EINVAL;
+  # when given as `false`, no exceptions are rescued.
   #
-  def find(*paths) # :yield: path
-    block_given? or return enum_for(__method__, *paths)
+  # Note that these exceptions may be ignored only in `Find` traversal code;
+  # an exception raised before traversal begins,
+  # or raised while in the block is not ignored.
+  # Each of the calls below raises an Errno::ENOENT exception that is not ignored:
+  #
+  # ```ruby
+  # Find.find('nosuch') { }
+  # Find.find('lib') {|entry| raise Errno::ENOENT }
+  # ```
+  #
+  # With no block given, returns a new Enumerator.
+  def find(*paths, ignore_error: true) # :yield: path
+    block_given? or return enum_for(__method__, *paths, ignore_error: ignore_error)
 
-    paths.collect!{|d| raise Errno::ENOENT unless File.exist?(d); d.dup}
-    while file = paths.shift
-      catch(:prune) do
-        yield file.dup.taint
-        begin
-          s = File.lstat(file)
-        rescue Errno::ENOENT, Errno::EACCES, Errno::ENOTDIR, Errno::ELOOP, Errno::ENAMETOOLONG
-          next
-        end
-        if s.directory? then
+    fs_encoding = Encoding.find("filesystem")
+
+    paths.collect!{|d| raise Errno::ENOENT, d unless File.exist?(d); d.dup}.each do |path|
+      path = path.to_path if path.respond_to? :to_path
+      enc = path.encoding == Encoding::US_ASCII ? fs_encoding : path.encoding
+      ps = [path]
+      while file = ps.shift
+        catch(:prune) do
+          yield file.dup
           begin
-            fs = Dir.entries(file)
-          rescue Errno::ENOENT, Errno::EACCES, Errno::ENOTDIR, Errno::ELOOP, Errno::ENAMETOOLONG
+            s = File.lstat(file)
+          rescue Errno::ENOENT, Errno::EACCES, Errno::ENOTDIR, Errno::ELOOP, Errno::ENAMETOOLONG, Errno::EINVAL
+            raise unless ignore_error
             next
           end
-          fs.sort!
-          fs.reverse_each {|f|
-            next if f == "." or f == ".."
-            f = File.join(file, f)
-            paths.unshift f.untaint
-          }
+          if s.directory? then
+            begin
+              fs = Dir.children(file, encoding: enc)
+            rescue Errno::ENOENT, Errno::EACCES, Errno::ENOTDIR, Errno::ELOOP, Errno::ENAMETOOLONG, Errno::EINVAL
+              raise unless ignore_error
+              next
+            end
+            fs.sort!
+            fs.reverse_each {|f|
+              f = File.join(file, f)
+              ps.unshift f
+            }
+          end
         end
       end
     end
+    nil
   end
 
+  # :markup: markdown
+  #
+  # call-seq:
+  #   Find.prune
+  #
+  # This method is meaningful only within a block given with Find.find.
   #
-  # Skips the current file or directory, restarting the loop with the next
-  # entry. If the current file is a directory, that directory will not be
-  # recursively entered. Meaningful only within the block associated with
-  # Find::find.
+  # Inside such a block,
+  # "prunes" the traversed file tree by not descending into the current directory:
   #
-  # See the +Find+ module documentation for an example.
+  # ```ruby
+  # files = []
+  # Find.find('.') do |path|
+  #   Find.prune if File.basename(path) == 'test'
+  #   next unless File.file?(path) && File.extname(path) == '.rb'
+  #   files << path
+  # end
+  # files.size    # => 6690
+  # files.take(3) # => ["./KNOWNBUGS.rb", "./array.rb", "./ast.rb"]
+  # ```
   #
   def prune
     throw :prune
diff --git a/lib/forwardable.rb b/lib/forwardable.rb
index 2b71b904d0..175d6d9c6b 100644
--- a/lib/forwardable.rb
+++ b/lib/forwardable.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   forwardable.rb -
 #       $Release Version: 1.1$
@@ -7,29 +8,58 @@
 #       Revised by Daniel J. Berger with suggestions from Florian Gross.
 #
 #       Documentation by James Edward Gray II and Gavin Sinclair
+
+
+
+# The Forwardable module provides delegation of specified
+# methods to a designated object, using the methods #def_delegator
+# and #def_delegators.
 #
-# == Introduction
+# For example, say you have a class RecordCollection which
+# contains an array <tt>@records</tt>.  You could provide the lookup method
+# #record_number(), which simply calls #[] on the <tt>@records</tt>
+# array, like this:
 #
-# This library allows you delegate method calls to an object, on a method by
-# method basis.
+#   require 'forwardable'
 #
-# == Notes
+#   class RecordCollection
+#     attr_accessor :records
+#     extend Forwardable
+#     def_delegator :@records, :[], :record_number
+#   end
 #
-# Be advised, RDoc will not detect delegated methods.
+# We can use the lookup method like so:
 #
-# <b>forwardable.rb provides single-method delegation via the
-# def_delegator() and def_delegators() methods.  For full-class
-# delegation via DelegateClass(), see delegate.rb.</b>
+#   r = RecordCollection.new
+#   r.records = [4,5,6]
+#   r.record_number(0)  # => 4
 #
-# == Examples
+# Further, if you wish to provide the methods #size, #<<, and #map,
+# all of which delegate to @records, this is how you can do it:
+#
+#   class RecordCollection # re-open RecordCollection class
+#     def_delegators :@records, :size, :<<, :map
+#   end
 #
-# === Forwardable
+#   r = RecordCollection.new
+#   r.records = [1,2,3]
+#   r.record_number(0)   # => 1
+#   r.size               # => 3
+#   r << 4               # => [1, 2, 3, 4]
+#   r.map { |x| x * 2 }  # => [2, 4, 6, 8]
 #
-# Forwardable makes building a new class based on existing work, with a proper
-# interface, almost trivial.  We want to rely on what has come before obviously,
-# but with delegation we can take just the methods we need and even rename them
-# as appropriate.  In many cases this is preferable to inheritance, which gives
-# us the entire old interface, even if much of it isn't needed.
+# You can even extend regular objects with Forwardable.
+#
+#   my_hash = Hash.new
+#   my_hash.extend Forwardable              # prepare object for delegation
+#   my_hash.def_delegator "STDOUT", "puts"  # add delegation for STDOUT.puts()
+#   my_hash.puts "Howdy!"
+#
+# == Another example
+#
+# You could use Forwardable as an alternative to inheritance, when you don't want
+# to inherit all methods from the superclass. For instance, here is how you might
+# add a range of +Array+ instance methods to a new class +Queue+:
 #
 #   class Queue
 #     extend Forwardable
@@ -46,7 +76,7 @@
 #     def_delegators :@q, :clear, :first, :push, :shift, :size
 #   end
 #
-#   q = Queue.new
+#   q = Thread::Queue.new
 #   q.enq 1, 2, 3, 4, 5
 #   q.push 6
 #
@@ -60,7 +90,7 @@
 #   q.clear
 #   puts q.first
 #
-# <i>Prints:</i>
+# This should output:
 #
 #   2
 #   3
@@ -70,77 +100,32 @@
 #   Ruby
 #   nil
 #
-# SingleForwardable can be used to setup delegation at the object level as well.
-#
-#    printer = String.new
-#    printer.extend SingleForwardable        # prepare object for delegation
-#    printer.def_delegator "STDOUT", "puts"  # add delegation for STDOUT.puts()
-#    printer.puts "Howdy!"
-#
-# Also, SingleForwardable can be use to Class or Module.
-#
-#    module Facade
-#      extend SingleForwardable
-#      def_delegator :Implementation, :service
-#
-#      class Implementation
-#         def service...
-#      end
-#    end
-#
-# If you want to use both Forwardable and SingleForwardable, you can
-# use methods def_instance_delegator and def_single_delegator, etc.
-#
-# If the object isn't a Module and Class, You can too extend
-# Forwardable module.
-#    printer = String.new
-#    printer.extend Forwardable              # prepare object for delegation
-#    printer.def_delegator "STDOUT", "puts"  # add delegation for STDOUT.puts()
-#    printer.puts "Howdy!"
-#
-# <i>Prints:</i>
-#
-#    Howdy!
-
-#
-# The Forwardable module provides delegation of specified
-# methods to a designated object, using the methods #def_delegator
-# and #def_delegators.
-#
-# For example, say you have a class RecordCollection which
-# contains an array <tt>@records</tt>.  You could provide the lookup method
-# #record_number(), which simply calls #[] on the <tt>@records</tt>
-# array, like this:
-#
-#   class RecordCollection
-#     extend Forwardable
-#     def_delegator :@records, :[], :record_number
-#   end
+# == Notes
 #
-# Further, if you wish to provide the methods #size, #<<, and #map,
-# all of which delegate to @records, this is how you can do it:
+# Be advised, RDoc will not detect delegated methods.
 #
-#   class RecordCollection
-#     # extend Forwardable, but we did that above
-#     def_delegators :@records, :size, :<<, :map
-#   end
-#   f = Foo.new
-#   f.printf ...
-#   f.gets
-#   f.content_at(1)
+# +forwardable.rb+ provides single-method delegation via the def_delegator and
+# def_delegators methods. For full-class delegation via DelegateClass, see
+# +delegate.rb+.
 #
-# Also see the example at forwardable.rb.
-
 module Forwardable
-  FORWARDABLE_VERSION = "1.1.0"
+  # Version of +forwardable.rb+
+  VERSION = "1.4.0"
+  VERSION.freeze
+
+  # Version for backward compatibility
+  FORWARDABLE_VERSION = VERSION
+  FORWARDABLE_VERSION.freeze
 
   @debug = nil
   class << self
+    # ignored
     attr_accessor :debug
   end
 
   # Takes a hash as its argument.  The key is a symbol or an array of
-  # symbols.  These symbols correspond to method names.  The value is
+  # symbols.  These symbols correspond to method names, instance variable
+  # names, or constant names (see def_delegator).  The value is
   # the accessor to which the methods will be delegated.
   #
   # :call-seq:
@@ -148,12 +133,13 @@ module Forwardable
   #    delegate [method, method, ...] => accessor
   #
   def instance_delegate(hash)
-    hash.each{ |methods, accessor|
-      methods = [methods] unless methods.respond_to?(:each)
-      methods.each{ |method|
-        def_instance_delegator(accessor, method)
-      }
-    }
+    hash.each do |methods, accessor|
+      unless defined?(methods.each)
+        def_instance_delegator(accessor, methods)
+      else
+        methods.each {|method| def_instance_delegator(accessor, method)}
+      end
+    end
   end
 
   #
@@ -168,60 +154,110 @@ module Forwardable
   #   def_delegator :@records, :map
   #
   def def_instance_delegators(accessor, *methods)
-    methods.delete("__send__")
-    methods.delete("__id__")
-    for method in methods
+    methods.each do |method|
+      next if /\A__(?:send|id)__\z/ =~ method
       def_instance_delegator(accessor, method)
     end
   end
 
   # Define +method+ as delegator instance method with an optional
   # alias name +ali+. Method calls to +ali+ will be delegated to
-  # +accessor.method+. 
+  # +accessor.method+.  +accessor+ should be a method name, instance
+  # variable name, or constant name.  Use the full path to the
+  # constant if providing the constant name.
+  # Returns the name of the method defined.
   #
   #   class MyQueue
+  #     CONST = 1
   #     extend Forwardable
   #     attr_reader :queue
   #     def initialize
   #       @queue = []
   #     end
-  #     
+  #
   #     def_delegator :@queue, :push, :mypush
+  #     def_delegator 'MyQueue::CONST', :to_i
   #   end
   #
   #   q = MyQueue.new
   #   q.mypush 42
   #   q.queue    #=> [42]
   #   q.push 23  #=> NoMethodError
+  #   q.to_i     #=> 1
   #
   def def_instance_delegator(accessor, method, ali = method)
-    line_no = __LINE__; str = %{
-      def #{ali}(*args, &block)
-        begin
-          #{accessor}.__send__(:#{method}, *args, &block)
-        rescue Exception
-          $@.delete_if{|s| %r"#{Regexp.quote(__FILE__)}"o =~ s} unless Forwardable::debug
-          ::Kernel::raise
-        end
-      end
-    }
-    # If it's not a class or module, it's an instance
-    begin
-      module_eval(str, __FILE__, line_no)
-    rescue
-      instance_eval(str, __FILE__, line_no)
-    end
+    gen = Forwardable._delegator_method(self, accessor, method, ali)
 
+    # If it's not a class or module, it's an instance
+    mod = Module === self ? self : singleton_class
+    mod.module_eval(&gen)
   end
 
   alias delegate instance_delegate
   alias def_delegators def_instance_delegators
   alias def_delegator def_instance_delegator
+
+  # :nodoc:
+  def self._delegator_method(obj, accessor, method, ali)
+    accessor = accessor.to_s unless Symbol === accessor
+
+    if Module === obj ?
+         obj.method_defined?(accessor) || obj.private_method_defined?(accessor) :
+         obj.respond_to?(accessor, true)
+      accessor = "(#{accessor}())"
+    end
+
+    args = RUBY_VERSION >= '2.7' ? '...' : '*args, &block'
+    method_call = ".__send__(:#{method}, #{args})"
+    if method.match?(/\A[_a-zA-Z]\w*[?!]?\z/)
+      loc, = caller_locations(2,1)
+      pre = "_ ="
+      mesg = "#{Module === obj ? obj : obj.class}\##{ali} at #{loc.path}:#{loc.lineno} forwarding to private method "
+      method_call = <<~RUBY.chomp
+        if defined?(_.#{method})
+          _.#{method}(#{args})
+        else
+          ::Kernel.warn #{mesg.dump}"\#{_.class}"'##{method}', uplevel: 1
+          _#{method_call}
+        end
+      RUBY
+    end
+
+    eval(<<~RUBY, nil, __FILE__, __LINE__ + 1)
+      proc do
+        def #{ali}(#{args})
+          #{pre}#{accessor}
+          #{method_call}
+        end
+      end
+    RUBY
+  end
 end
 
+# SingleForwardable can be used to setup delegation at the object level as well.
+#
+#    printer = String.new
+#    printer.extend SingleForwardable        # prepare object for delegation
+#    printer.def_delegator "STDOUT", "puts"  # add delegation for STDOUT.puts()
+#    printer.puts "Howdy!"
+#
+# Also, SingleForwardable can be used to set up delegation for a Class or Module.
 #
-# Usage of The SingleForwardable is like Fowadable module.
+#   class Implementation
+#     def self.service
+#       puts "serviced!"
+#     end
+#   end
+#
+#   module Facade
+#     extend SingleForwardable
+#     def_delegator :Implementation, :service
+#   end
 #
+#   Facade.service #=> serviced!
+#
+# If you want to use both Forwardable and SingleForwardable, you can
+# use methods def_instance_delegator and def_single_delegator, etc.
 module SingleForwardable
   # Takes a hash as its argument.  The key is a symbol or an array of
   # symbols.  These symbols correspond to method names.  The value is
@@ -232,12 +268,13 @@ module SingleForwardable
   #    delegate [method, method, ...] => accessor
   #
   def single_delegate(hash)
-    hash.each{ |methods, accessor|
-      methods = [methods] unless methods.respond_to?(:each)
-      methods.each{ |method|
-        def_single_delegator(accessor, method)
-      }
-    }
+    hash.each do |methods, accessor|
+      unless defined?(methods.each)
+        def_single_delegator(accessor, methods)
+      else
+        methods.each {|method| def_single_delegator(accessor, method)}
+      end
+    end
   end
 
   #
@@ -252,31 +289,23 @@ module SingleForwardable
   #   def_delegator :@records, :map
   #
   def def_single_delegators(accessor, *methods)
-    methods.delete("__send__")
-    methods.delete("__id__")
-    for method in methods
+    methods.each do |method|
+      next if /\A__(?:send|id)__\z/ =~ method
       def_single_delegator(accessor, method)
     end
   end
 
+  # :call-seq:
+  #   def_single_delegator(accessor, method, new_name=method)
   #
-  # Defines a method _method_ which delegates to _obj_ (i.e. it calls
-  # the method of the same name in _obj_).  If _new_name_ is
+  # Defines a method _method_ which delegates to _accessor_ (i.e. it calls
+  # the method of the same name in _accessor_).  If _new_name_ is
   # provided, it is used as the name for the delegate method.
-  #
+  # Returns the name of the method defined.
   def def_single_delegator(accessor, method, ali = method)
-    str = %{
-      def #{ali}(*args, &block)
-        begin
-          #{accessor}.__send__(:#{method}, *args, &block)
-        rescue Exception
-          $@.delete_if{|s| %r"#{Regexp.quote(__FILE__)}"o =~ s} unless Forwardable::debug
-          ::Kernel::raise
-        end
-      end
-    }
+    gen = Forwardable._delegator_method(self, accessor, method, ali)
 
-    instance_eval(str, __FILE__, __LINE__)
+    instance_eval(&gen)
   end
 
   alias delegate single_delegate
diff --git a/lib/forwardable/forwardable.gemspec b/lib/forwardable/forwardable.gemspec
new file mode 100644
index 0000000000..1b539bcfcb
--- /dev/null
+++ b/lib/forwardable/forwardable.gemspec
@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+name = File.basename(__FILE__, ".gemspec")
+version = ["lib", Array.new(name.count("-")+1, "..").join("/")].find do |dir|
+  break File.foreach(File.join(__dir__, dir, "#{name.tr('-', '/')}.rb")) do |line|
+    /^\s*VERSION\s*=\s*"(.*)"/ =~ line and break $1
+  end rescue nil
+end
+
+Gem::Specification.new do |spec|
+  spec.name          = name
+  spec.version       = version
+  spec.authors       = ["Keiju ISHITSUKA"]
+  spec.email         = ["keiju@ruby-lang.org"]
+
+  spec.summary       = %q{Provides delegation of specified methods to a designated object.}
+  spec.description   = %q{Provides delegation of specified methods to a designated object.}
+  spec.homepage      = "https://github.com/ruby/forwardable"
+  spec.licenses      = ["Ruby", "BSD-2-Clause"]
+
+  spec.required_ruby_version = '>= 2.4.0'
+  spec.files         = ["forwardable.gemspec", "lib/forwardable.rb"]
+  spec.bindir        = "exe"
+  spec.executables   = []
+  spec.require_paths = ["lib"]
+end
diff --git a/lib/getoptlong.rb b/lib/getoptlong.rb
deleted file mode 100644
index 259382e8ec..0000000000
--- a/lib/getoptlong.rb
+++ /dev/null
@@ -1,612 +0,0 @@
-#
-# GetoptLong for Ruby
-#
-# Copyright (C) 1998, 1999, 2000  Motoyuki Kasahara.
-#
-# You may redistribute and/or modify this library under the same license
-# terms as Ruby.
-#
-# See GetoptLong for documentation.
-#
-# Additional documents and the latest version of `getoptlong.rb' can be
-# found at http://www.sra.co.jp/people/m-kasahr/ruby/getoptlong/
-
-# The GetoptLong class allows you to parse command line options similarly to
-# the GNU getopt_long() C library call. Note, however, that GetoptLong is a
-# pure Ruby implementation.
-#
-# GetoptLong allows for POSIX-style options like <tt>--file</tt> as well
-# as single letter options like <tt>-f</tt>
-#
-# The empty option <tt>--</tt> (two minus symbols) is used to end option
-# processing. This can be particularly important if options have optional
-# arguments.
-#
-# Here is a simple example of usage:
-#
-#     require 'getoptlong'
-#
-#     opts = GetoptLong.new(
-#       [ '--help', '-h', GetoptLong::NO_ARGUMENT ],
-#       [ '--repeat', '-n', GetoptLong::REQUIRED_ARGUMENT ],
-#       [ '--name', GetoptLong::OPTIONAL_ARGUMENT ]
-#     )
-#
-#     dir = nil
-#     name = nil
-#     repetitions = 1
-#     opts.each do |opt, arg|
-#       case opt
-#         when '--help'
-#           puts <<-EOF
-#     hello [OPTION] ... DIR
-#
-#     -h, --help:
-#        show help
-#
-#     --repeat x, -n x:
-#        repeat x times
-#
-#     --name [name]:
-#        greet user by name, if name not supplied default is John
-#
-#     DIR: The directory in which to issue the greeting.
-#           EOF
-#         when '--repeat'
-#           repetitions = arg.to_i
-#         when '--name'
-#           if arg == ''
-#             name = 'John'
-#           else
-#             name = arg
-#           end
-#       end
-#     end
-#
-#     if ARGV.length != 1
-#       puts "Missing dir argument (try --help)"
-#       exit 0
-#     end
-#
-#     dir = ARGV.shift
-#
-#     Dir.chdir(dir)
-#     for i in (1..repetitions)
-#       print "Hello"
-#       if name
-#         print ", #{name}"
-#       end
-#       puts
-#     end
-#
-# Example command line:
-#
-#     hello -n 6 --name -- /tmp
-#
-class GetoptLong
-  #
-  # Orderings.
-  #
-  ORDERINGS = [REQUIRE_ORDER = 0, PERMUTE = 1, RETURN_IN_ORDER = 2]
-
-  #
-  # Argument flags.
-  #
-  ARGUMENT_FLAGS = [NO_ARGUMENT = 0, REQUIRED_ARGUMENT = 1,
-    OPTIONAL_ARGUMENT = 2]
-
-  #
-  # Status codes.
-  #
-  STATUS_YET, STATUS_STARTED, STATUS_TERMINATED = 0, 1, 2
-
-  #
-  # Error types.
-  #
-  class Error  < StandardError; end
-  class AmbiguousOption   < Error; end
-  class NeedlessArgument < Error; end
-  class MissingArgument  < Error; end
-  class InvalidOption    < Error; end
-
-  #
-  # Set up option processing.
-  #
-  # The options to support are passed to new() as an array of arrays.
-  # Each sub-array contains any number of String option names which carry
-  # the same meaning, and one of the following flags:
-  #
-  # GetoptLong::NO_ARGUMENT :: Option does not take an argument.
-  #
-  # GetoptLong::REQUIRED_ARGUMENT :: Option always takes an argument.
-  #
-  # GetoptLong::OPTIONAL_ARGUMENT :: Option may or may not take an argument.
-  #
-  # The first option name is considered to be the preferred (canonical) name.
-  # Other than that, the elements of each sub-array can be in any order.
-  #
-  def initialize(*arguments)
-    #
-    # Current ordering.
-    #
-    if ENV.include?('POSIXLY_CORRECT')
-      @ordering = REQUIRE_ORDER
-    else
-      @ordering = PERMUTE
-    end
-
-    #
-    # Hash table of option names.
-    # Keys of the table are option names, and their values are canonical
-    # names of the options.
-    #
-    @canonical_names = Hash.new
-
-    #
-    # Hash table of argument flags.
-    # Keys of the table are option names, and their values are argument
-    # flags of the options.
-    #
-    @argument_flags = Hash.new
-
-    #
-    # Whether error messages are output to $stderr.
-    #
-    @quiet = FALSE
-
-    #
-    # Status code.
-    #
-    @status = STATUS_YET
-
-    #
-    # Error code.
-    #
-    @error = nil
-
-    #
-    # Error message.
-    #
-    @error_message = nil
-
-    #
-    # Rest of catenated short options.
-    #
-    @rest_singles = ''
-
-    #
-    # List of non-option-arguments.
-    # Append them to ARGV when option processing is terminated.
-    #
-    @non_option_arguments = Array.new
-
-    if 0 < arguments.length
-      set_options(*arguments)
-    end
-  end
-
-  #
-  # Set the handling of the ordering of options and arguments.
-  # A RuntimeError is raised if option processing has already started.
-  #
-  # The supplied value must be a member of GetoptLong::ORDERINGS. It alters
-  # the processing of options as follows:
-  #
-  # <b>REQUIRE_ORDER</b> :
-  #
-  # Options are required to occur before non-options.
-  #
-  # Processing of options ends as soon as a word is encountered that has not
-  # been preceded by an appropriate option flag.
-  #
-  # For example, if -a and -b are options which do not take arguments,
-  # parsing command line arguments of '-a one -b two' would result in
-  # 'one', '-b', 'two' being left in ARGV, and only ('-a', '') being
-  # processed as an option/arg pair.
-  #
-  # This is the default ordering, if the environment variable
-  # POSIXLY_CORRECT is set. (This is for compatibility with GNU getopt_long.)
-  #
-  # <b>PERMUTE</b> :
-  #
-  # Options can occur anywhere in the command line parsed. This is the
-  # default behavior.
-  #
-  # Every sequence of words which can be interpreted as an option (with or
-  # without argument) is treated as an option; non-option words are skipped.
-  #
-  # For example, if -a does not require an argument and -b optionally takes
-  # an argument, parsing '-a one -b two three' would result in ('-a','') and
-  # ('-b', 'two') being processed as option/arg pairs, and 'one','three'
-  # being left in ARGV.
-  #
-  # If the ordering is set to PERMUTE but the environment variable
-  # POSIXLY_CORRECT is set, REQUIRE_ORDER is used instead. This is for
-  # compatibility with GNU getopt_long.
-  #
-  # <b>RETURN_IN_ORDER</b> :
-  #
-  # All words on the command line are processed as options. Words not
-  # preceded by a short or long option flag are passed as arguments
-  # with an option of '' (empty string).
-  #
-  # For example, if -a requires an argument but -b does not, a command line
-  # of '-a one -b two three' would result in option/arg pairs of ('-a', 'one')
-  # ('-b', ''), ('', 'two'), ('', 'three') being processed.
-  #
-  def ordering=(ordering)
-    #
-    # The method is failed if option processing has already started.
-    #
-    if @status != STATUS_YET
-      set_error(ArgumentError, "argument error")
-      raise RuntimeError,
-        "invoke ordering=, but option processing has already started"
-    end
-
-    #
-    # Check ordering.
-    #
-    if !ORDERINGS.include?(ordering)
-      raise ArgumentError, "invalid ordering `#{ordering}'"
-    end
-    if ordering == PERMUTE && ENV.include?('POSIXLY_CORRECT')
-      @ordering = REQUIRE_ORDER
-    else
-      @ordering = ordering
-    end
-  end
-
-  #
-  # Return ordering.
-  #
-  attr_reader :ordering
-
-  #
-  # Set options. Takes the same argument as GetoptLong.new.
-  #
-  # Raises a RuntimeError if option processing has already started.
-  #
-  def set_options(*arguments)
-    #
-    # The method is failed if option processing has already started.
-    #
-    if @status != STATUS_YET
-      raise RuntimeError,
-        "invoke set_options, but option processing has already started"
-    end
-
-    #
-    # Clear tables of option names and argument flags.
-    #
-    @canonical_names.clear
-    @argument_flags.clear
-
-    arguments.each do |arg|
-      if !arg.is_a?(Array)
-       raise ArgumentError, "the option list contains non-Array argument"
-      end
-
-      #
-      # Find an argument flag and it set to `argument_flag'.
-      #
-      argument_flag = nil
-      arg.each do |i|
-        if ARGUMENT_FLAGS.include?(i)
-          if argument_flag != nil
-            raise ArgumentError, "too many argument-flags"
-          end
-          argument_flag = i
-        end
-      end
-
-      raise ArgumentError, "no argument-flag" if argument_flag == nil
-
-      canonical_name = nil
-      arg.each do |i|
-        #
-        # Check an option name.
-        #
-        next if i == argument_flag
-        begin
-          if !i.is_a?(String) || i !~ /^-([^-]|-.+)$/
-            raise ArgumentError, "an invalid option `#{i}'"
-          end
-          if (@canonical_names.include?(i))
-            raise ArgumentError, "option redefined `#{i}'"
-          end
-        rescue
-          @canonical_names.clear
-          @argument_flags.clear
-          raise
-        end
-
-        #
-        # Register the option (`i') to the `@canonical_names' and
-        # `@canonical_names' Hashes.
-        #
-        if canonical_name == nil
-          canonical_name = i
-        end
-        @canonical_names[i] = canonical_name
-        @argument_flags[i] = argument_flag
-      end
-      raise ArgumentError, "no option name" if canonical_name == nil
-    end
-    return self
-  end
-
-  #
-  # Set/Unset `quiet' mode.
-  #
-  attr_writer :quiet
-
-  #
-  # Return the flag of `quiet' mode.
-  #
-  attr_reader :quiet
-
-  #
-  # `quiet?' is an alias of `quiet'.
-  #
-  alias quiet? quiet
-
-  #
-  # Explicitly terminate option processing.
-  #
-  def terminate
-    return nil if @status == STATUS_TERMINATED
-    raise RuntimeError, "an error has occured" if @error != nil
-
-    @status = STATUS_TERMINATED
-    @non_option_arguments.reverse_each do |argument|
-      ARGV.unshift(argument)
-    end
-
-    @canonical_names = nil
-    @argument_flags = nil
-    @rest_singles = nil
-    @non_option_arguments = nil
-
-    return self
-  end
-
-  #
-  # Returns true if option processing has terminated, false otherwise.
-  #
-  def terminated?
-    return @status == STATUS_TERMINATED
-  end
-
-  #
-  # Set an error (a protected method).
-  #
-  def set_error(type, message)
-    $stderr.print("#{$0}: #{message}\n") if !@quiet
-
-    @error = type
-    @error_message = message
-    @canonical_names = nil
-    @argument_flags = nil
-    @rest_singles = nil
-    @non_option_arguments = nil
-
-    raise type, message
-  end
-  protected :set_error
-
-  #
-  # Examine whether an option processing is failed.
-  #
-  attr_reader :error
-
-  #
-  # `error?' is an alias of `error'.
-  #
-  alias error? error
-
-  # Return the appropriate error message in POSIX-defined format.
-  # If no error has occurred, returns nil.
-  #
-  def error_message
-    return @error_message
-  end
-
-  #
-  # Get next option name and its argument, as an Array of two elements.
-  #
-  # The option name is always converted to the first (preferred)
-  # name given in the original options to GetoptLong.new.
-  #
-  # Example: ['--option', 'value']
-  #
-  # Returns nil if the processing is complete (as determined by
-  # STATUS_TERMINATED).
-  #
-  def get
-    option_name, option_argument = nil, ''
-
-    #
-    # Check status.
-    #
-    return nil if @error != nil
-    case @status
-    when STATUS_YET
-      @status = STATUS_STARTED
-    when STATUS_TERMINATED
-      return nil
-    end
-
-    #
-    # Get next option argument.
-    #
-    if 0 < @rest_singles.length
-      argument = '-' + @rest_singles
-    elsif (ARGV.length == 0)
-      terminate
-      return nil
-    elsif @ordering == PERMUTE
-      while 0 < ARGV.length && ARGV[0] !~ /^-./
-        @non_option_arguments.push(ARGV.shift)
-      end
-      if ARGV.length == 0
-        terminate
-        return nil
-      end
-      argument = ARGV.shift
-    elsif @ordering == REQUIRE_ORDER
-      if (ARGV[0] !~ /^-./)
-        terminate
-        return nil
-      end
-      argument = ARGV.shift
-    else
-      argument = ARGV.shift
-    end
-
-    #
-    # Check the special argument `--'.
-    # `--' indicates the end of the option list.
-    #
-    if argument == '--' && @rest_singles.length == 0
-      terminate
-      return nil
-    end
-
-    #
-    # Check for long and short options.
-    #
-    if argument =~ /^(--[^=]+)/ && @rest_singles.length == 0
-      #
-      # This is a long style option, which start with `--'.
-      #
-      pattern = $1
-      if @canonical_names.include?(pattern)
-        option_name = pattern
-      else
-        #
-        # The option `option_name' is not registered in `@canonical_names'.
-        # It may be an abbreviated.
-        #
-        matches = []
-        @canonical_names.each_key do |key|
-          if key.index(pattern) == 0
-            option_name = key
-            matches << key
-          end
-        end
-        if 2 <= matches.length
-          set_error(AmbiguousOption, "option `#{argument}' is ambiguous between #{matches.join(', ')}")
-        elsif matches.length == 0
-          set_error(InvalidOption, "unrecognized option `#{argument}'")
-        end
-      end
-
-      #
-      # Check an argument to the option.
-      #
-      if @argument_flags[option_name] == REQUIRED_ARGUMENT
-        if argument =~ /=(.*)$/
-          option_argument = $1
-        elsif 0 < ARGV.length
-          option_argument = ARGV.shift
-        else
-          set_error(MissingArgument,
-                    "option `#{argument}' requires an argument")
-        end
-      elsif @argument_flags[option_name] == OPTIONAL_ARGUMENT
-        if argument =~ /=(.*)$/
-          option_argument = $1
-        elsif 0 < ARGV.length && ARGV[0] !~ /^-./
-          option_argument = ARGV.shift
-        else
-          option_argument = ''
-        end
-      elsif argument =~ /=(.*)$/
-        set_error(NeedlessArgument,
-                  "option `#{option_name}' doesn't allow an argument")
-      end
-
-    elsif argument =~ /^(-(.))(.*)/
-      #
-      # This is a short style option, which start with `-' (not `--').
-      # Short options may be catenated (e.g. `-l -g' is equivalent to
-      # `-lg').
-      #
-      option_name, ch, @rest_singles = $1, $2, $3
-
-      if @canonical_names.include?(option_name)
-        #
-        # The option `option_name' is found in `@canonical_names'.
-        # Check its argument.
-        #
-        if @argument_flags[option_name] == REQUIRED_ARGUMENT
-          if 0 < @rest_singles.length
-            option_argument = @rest_singles
-            @rest_singles = ''
-          elsif 0 < ARGV.length
-            option_argument = ARGV.shift
-          else
-            # 1003.2 specifies the format of this message.
-            set_error(MissingArgument, "option requires an argument -- #{ch}")
-          end
-        elsif @argument_flags[option_name] == OPTIONAL_ARGUMENT
-          if 0 < @rest_singles.length
-            option_argument = @rest_singles
-            @rest_singles = ''
-          elsif 0 < ARGV.length && ARGV[0] !~ /^-./
-            option_argument = ARGV.shift
-          else
-            option_argument = ''
-          end
-        end
-      else
-        #
-        # This is an invalid option.
-        # 1003.2 specifies the format of this message.
-        #
-        if ENV.include?('POSIXLY_CORRECT')
-          set_error(InvalidOption, "invalid option -- #{ch}")
-        else
-          set_error(InvalidOption, "invalid option -- #{ch}")
-        end
-      end
-    else
-      #
-      # This is a non-option argument.
-      # Only RETURN_IN_ORDER falled into here.
-      #
-      return '', argument
-    end
-
-    return @canonical_names[option_name], option_argument
-  end
-
-  #
-  # `get_option' is an alias of `get'.
-  #
-  alias get_option get
-
-  # Iterator version of `get'.
-  #
-  # The block is called repeatedly with two arguments:
-  # The first is the option name.
-  # The second is the argument which followed it (if any).
-  # Example: ('--opt', 'value')
-  #
-  # The option name is always converted to the first (preferred)
-  # name given in the original options to GetoptLong.new.
-  #
-  def each
-    loop do
-      option_name, option_argument = get_option
-      break if option_name == nil
-      yield option_name, option_argument
-    end
-  end
-
-  #
-  # `each_option' is an alias of `each'.
-  #
-  alias each_option each
-end
diff --git a/lib/gserver.rb b/lib/gserver.rb
deleted file mode 100644
index 4dd5ad0c08..0000000000
--- a/lib/gserver.rb
+++ /dev/null
@@ -1,309 +0,0 @@
-#
-# Copyright (C) 2001 John W. Small All Rights Reserved
-#
-# Author::        John W. Small
-# Documentation:: Gavin Sinclair
-# Licence::       Ruby License
-
-require "socket"
-require "thread"
-
-#
-# GServer implements a generic server, featuring thread pool management,
-# simple logging, and multi-server management.  See HttpServer in
-# <tt>xmlrpc/httpserver.rb</tt> in the Ruby standard library for an example of
-# GServer in action.
-#
-# Any kind of application-level server can be implemented using this class.
-# It accepts multiple simultaneous connections from clients, up to an optional
-# maximum number.  Several _services_ (i.e. one service per TCP port) can be
-# run simultaneously, and stopped at any time through the class method
-# <tt>GServer.stop(port)</tt>.  All the threading issues are handled, saving
-# you the effort.  All events are optionally logged, but you can provide your
-# own event handlers if you wish.
-#
-# == Example
-#
-# Using GServer is simple.  Below we implement a simple time server, run it,
-# query it, and shut it down.  Try this code in +irb+:
-#
-#   require 'gserver'
-#
-#   #
-#   # A server that returns the time in seconds since 1970.
-#   #
-#   class TimeServer < GServer
-#     def initialize(port=10001, *args)
-#       super(port, *args)
-#     end
-#     def serve(io)
-#       io.puts(Time.now.to_s)
-#     end
-#   end
-#
-#   # Run the server with logging enabled (it's a separate thread).
-#   server = TimeServer.new
-#   server.audit = true                  # Turn logging on.
-#   server.start
-#
-#   # *** Now point your browser to http://localhost:10001 to see it working ***
-#
-#   # See if it's still running.
-#   GServer.in_service?(10001)           # -> true
-#   server.stopped?                      # -> false
-#
-#   # Shut the server down gracefully.
-#   server.shutdown
-#
-#   # Alternatively, stop it immediately.
-#   GServer.stop(10001)
-#   # or, of course, "server.stop".
-#
-# All the business of accepting connections and exception handling is taken
-# care of.  All we have to do is implement the method that actually serves the
-# client.
-#
-# === Advanced
-#
-# As the example above shows, the way to use GServer is to subclass it to
-# create a specific server, overriding the +serve+ method.  You can override
-# other methods as well if you wish, perhaps to collect statistics, or emit
-# more detailed logging.
-#
-# * #connecting
-# * #disconnecting
-# * #starting
-# * #stopping
-#
-# The above methods are only called if auditing is enabled, via #audit=.
-#
-# You can also override #log and #error if, for example, you wish to use a
-# more sophisticated logging system.
-#
-class GServer
-
-  DEFAULT_HOST = "127.0.0.1"
-
-  def serve(io)
-  end
-
-  @@services = {}   # Hash of opened ports, i.e. services
-  @@servicesMutex = Mutex.new
-
-  # Stop the server running on the given port, bound to the given host
-  #
-  # +port+:: port, as a FixNum, of the server to stop
-  # +host+:: host on which to find the server to stop
-  def GServer.stop(port, host = DEFAULT_HOST)
-    @@servicesMutex.synchronize {
-      @@services[host][port].stop
-    }
-  end
-
-  # Check if a server is running on the given port and host
-  #
-  # +port+:: port, as a FixNum, of the server to check
-  # +host+:: host on which to find the server to check
-  #
-  # Returns true if a server is running on that port and host.
-  def GServer.in_service?(port, host = DEFAULT_HOST)
-    @@services.has_key?(host) and
-      @@services[host].has_key?(port)
-  end
-
-  # Stop the server
-  def stop
-    @connectionsMutex.synchronize  {
-      if @tcpServerThread
-        @tcpServerThread.raise "stop"
-      end
-    }
-  end
-
-  # Returns true if the server has stopped.
-  def stopped?
-    @tcpServerThread == nil
-  end
-
-  # Schedule a shutdown for the server
-  def shutdown
-    @shutdown = true
-  end
-
-  # Return the current number of connected clients
-  def connections
-    @connections.size
-  end
-
-  # Join with the server thread
-  def join
-    @tcpServerThread.join if @tcpServerThread
-  end
-
-  # Port on which to listen, as a FixNum
-  attr_reader :port
-  # Host on which to bind, as a String
-  attr_reader :host
-  # Maximum number of connections to accept at at ime, as a FixNum
-  attr_reader :maxConnections
-  # IO Device on which log messages should be written
-  attr_accessor :stdlog
-  # Set to true to cause the callbacks #connecting, #disconnecting, #starting,
-  # and #stopping to be called during the server's lifecycle
-  attr_accessor :audit
-  # Set to true to show more detailed logging
-  attr_accessor :debug
-
-  # Called when a client connects, if auditing is enabled.
-  #
-  # +client+:: a TCPSocket instances representing the client that connected
-  #
-  # Return true to allow this client to connect, false to prevent it.
-  def connecting(client)
-    addr = client.peeraddr
-    log("#{self.class.to_s} #{@host}:#{@port} client:#{addr[1]} " +
-        "#{addr[2]}<#{addr[3]}> connect")
-    true
-  end
-
-
-  # Called when a client disconnects, if audition is enabled.
-  #
-  # +clientPort+:: the port of the client that is connecting
-  def disconnecting(clientPort)
-    log("#{self.class.to_s} #{@host}:#{@port} " +
-      "client:#{clientPort} disconnect")
-  end
-
-  protected :connecting, :disconnecting
-
-  # Called when the server is starting up, if auditing is enabled.
-  def starting()
-    log("#{self.class.to_s} #{@host}:#{@port} start")
-  end
-
-  # Called when the server is shutting down, if auditing is enabled.
-  def stopping()
-    log("#{self.class.to_s} #{@host}:#{@port} stop")
-  end
-
-  protected :starting, :stopping
-
-  # Called if #debug is true whenever an unhandled exception is raised.
-  # This implementation simply logs the backtrace.
-  #
-  # +detail+:: The Exception that was caught
-  def error(detail)
-    log(detail.backtrace.join("\n"))
-  end
-
-  # Log a message to #stdlog, if it's defined.  This implementation
-  # outputs the timestamp and message to the log.
-  #
-  # +msg+:: the message to log
-  def log(msg)
-    if @stdlog
-      @stdlog.puts("[#{Time.new.ctime}] %s" % msg)
-      @stdlog.flush
-    end
-  end
-
-  protected :error, :log
-
-  # Create a new server
-  #
-  # +port+:: the port, as a FixNum, on which to listen.
-  # +host+:: the host to bind to
-  # +maxConnections+:: The maximum number of simultaneous connections to
-  #                    accept
-  # +stdlog+:: IO device on which to log messages
-  # +audit+:: if true, lifecycle callbacks will be called.  See #audit
-  # +debug+:: if true, error messages are logged.  See #debug
-  def initialize(port, host = DEFAULT_HOST, maxConnections = 4,
-    stdlog = $stderr, audit = false, debug = false)
-    @tcpServerThread = nil
-    @port = port
-    @host = host
-    @maxConnections = maxConnections
-    @connections = []
-    @connectionsMutex = Mutex.new
-    @connectionsCV = ConditionVariable.new
-    @stdlog = stdlog
-    @audit = audit
-    @debug = debug
-  end
-
-  # Start the server if it isn't already running
-  #
-  # +maxConnections+::
-  #   override +maxConnections+ given to the constructor.  A negative
-  #   value indicates that the value from the constructor should be used.
-  def start(maxConnections = -1)
-    raise "server is already running" if !stopped?
-    @shutdown = false
-    @maxConnections = maxConnections if maxConnections > 0
-    @@servicesMutex.synchronize  {
-      if GServer.in_service?(@port,@host)
-        raise "Port already in use: #{host}:#{@port}!"
-      end
-      @tcpServer = TCPServer.new(@host,@port)
-      @port = @tcpServer.addr[1]
-      @@services[@host] = {} unless @@services.has_key?(@host)
-      @@services[@host][@port] = self;
-    }
-    @tcpServerThread = Thread.new {
-      begin
-        starting if @audit
-        while !@shutdown
-          @connectionsMutex.synchronize  {
-             while @connections.size >= @maxConnections
-               @connectionsCV.wait(@connectionsMutex)
-             end
-          }
-          client = @tcpServer.accept
-          @connections << Thread.new(client)  { |myClient|
-            begin
-              myPort = myClient.peeraddr[1]
-              serve(myClient) if !@audit or connecting(myClient)
-            rescue => detail
-              error(detail) if @debug
-            ensure
-              begin
-                myClient.close
-              rescue
-              end
-              @connectionsMutex.synchronize {
-                @connections.delete(Thread.current)
-                @connectionsCV.signal
-              }
-              disconnecting(myPort) if @audit
-            end
-          }
-        end
-      rescue => detail
-        error(detail) if @debug
-      ensure
-        begin
-          @tcpServer.close
-        rescue
-        end
-        if @shutdown
-          @connectionsMutex.synchronize  {
-             while @connections.size > 0
-               @connectionsCV.wait(@connectionsMutex)
-             end
-          }
-        else
-          @connections.each { |c| c.raise "stop" }
-        end
-        @tcpServerThread = nil
-        @@servicesMutex.synchronize  {
-          @@services[@host].delete(@port)
-        }
-        stopping if @audit
-      end
-    }
-    self
-  end
-
-end
diff --git a/lib/ipaddr.gemspec b/lib/ipaddr.gemspec
new file mode 100644
index 0000000000..cabc9161ba
--- /dev/null
+++ b/lib/ipaddr.gemspec
@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+# coding: utf-8
+
+if File.exist?(File.expand_path("ipaddr.gemspec"))
+  lib = File.expand_path("../lib", __FILE__)
+  $LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
+
+  file = File.expand_path("ipaddr.rb", lib)
+else
+  # for ruby-core
+  file = File.expand_path("../ipaddr.rb", __FILE__)
+end
+
+version = File.foreach(file).find do |line|
+  /^\s*VERSION\s*=\s*["'](.*)["']/ =~ line and break $1
+end
+
+Gem::Specification.new do |spec|
+  spec.name          = "ipaddr"
+  spec.version       = version
+  spec.authors       = ["Akinori MUSHA", "Hajimu UMEMOTO"]
+  spec.email         = ["knu@idaemons.org", "ume@mahoroba.org"]
+
+  spec.summary       = %q{A class to manipulate an IP address in ruby}
+  spec.description   = <<-'DESCRIPTION'
+IPAddr provides a set of methods to manipulate an IP address.
+Both IPv4 and IPv6 are supported.
+  DESCRIPTION
+  spec.homepage      = "https://github.com/ruby/ipaddr"
+  spec.licenses      = ["Ruby", "BSD-2-Clause"]
+
+  spec.files         = ["LICENSE.txt", "README.md", "lib/ipaddr.rb"]
+  spec.require_paths = ["lib"]
+
+  spec.required_ruby_version = ">= 2.4"
+end
diff --git a/lib/ipaddr.rb b/lib/ipaddr.rb
index 15692cf4f8..70b804f642 100644
--- a/lib/ipaddr.rb
+++ b/lib/ipaddr.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 #
 # ipaddr.rb - A class to manipulate an IP address
 #
@@ -39,18 +40,20 @@ require 'socket'
 #   p ipaddr3                   #=> #<IPAddr: IPv4:192.168.2.0/255.255.255.0>
 
 class IPAddr
+  # The version string
+  VERSION = "1.2.9"
 
   # 32 bit mask for IPv4
   IN4MASK = 0xffffffff
-  # 128 bit mask for IPv4
+  # 128 bit mask for IPv6
   IN6MASK = 0xffffffffffffffffffffffffffffffff
   # Format string for IPv6
-  IN6FORMAT = (["%.4x"] * 8).join(':')
+  IN6FORMAT = (["%.4x"] * 8).join(':').freeze
 
   # Regexp _internally_ used for parsing IPv4 address.
   RE_IPV4ADDRLIKE = %r{
     \A
-    (\d+) \. (\d+) \. (\d+) \. (\d+)
+    \d+ \. \d+ \. \d+ \. \d+
     \z
   }x
 
@@ -82,27 +85,46 @@ class IPAddr
     \z
   }xi
 
+  # Generic IPAddr related error. Exceptions raised in this class should
+  # inherit from Error.
+  class Error < ArgumentError; end
+
+  # Raised when the provided IP address is an invalid address.
+  class InvalidAddressError < Error; end
+
+  # Raised when the address family is invalid such as an address with an
+  # unsupported family, an address with an inconsistent family, or an address
+  # who's family cannot be determined.
+  class AddressFamilyError < Error; end
+
+  # Raised when the address is an invalid length.
+  class InvalidPrefixError < InvalidAddressError; end
+
   # Returns the address family of this IP address.
   attr_reader :family
 
   # Creates a new ipaddr containing the given network byte ordered
   # string form of an IP address.
-  def IPAddr::new_ntoh(addr)
-    return IPAddr.new(IPAddr::ntop(addr))
+  def self.new_ntoh(addr)
+    return new(ntop(addr))
   end
 
   # Convert a network byte ordered string form of an IP address into
   # human readable form.
-  def IPAddr::ntop(addr)
-    case addr.size
+  # It expects the string to be encoded in Encoding::ASCII_8BIT (BINARY).
+  def self.ntop(addr)
+    if addr.is_a?(String) && addr.encoding != Encoding::BINARY
+      raise InvalidAddressError, "invalid encoding (given #{addr.encoding}, expected BINARY)"
+    end
+
+    case addr.bytesize
     when 4
-      s = addr.unpack('C4').join('.')
+      addr.unpack('C4').join('.')
     when 16
-      s = IN6FORMAT % addr.unpack('n8')
+      IN6FORMAT % addr.unpack('n8')
     else
-      raise ArgumentError, "unsupported address family"
+      raise AddressFamilyError, "unsupported address family"
     end
-    return s
   end
 
   # Returns a new ipaddr built by bitwise AND.
@@ -130,10 +152,27 @@ class IPAddr
     return self.clone.set(addr_mask(~@addr))
   end
 
+  # Returns a new ipaddr greater than the original address by offset
+  def +(offset)
+    self.clone.set(@addr + offset, @family)
+  end
+
+  # Returns a new ipaddr less than the original address by offset
+  def -(offset)
+    self.clone.set(@addr - offset, @family)
+  end
+
   # Returns true if two ipaddrs are equal.
   def ==(other)
+    if other.nil?
+      return false
+    end
+
     other = coerce_other(other)
-    return @family == other.family && @addr == other.to_i
+  rescue
+    false
+  else
+    @family == other.family && @addr == other.to_i
   end
 
   # Returns a new ipaddr built by masking IP address with the given
@@ -149,34 +188,15 @@ class IPAddr
   #   net1 = IPAddr.new("192.168.2.0/24")
   #   net2 = IPAddr.new("192.168.2.100")
   #   net3 = IPAddr.new("192.168.3.0")
+  #   net4 = IPAddr.new("192.168.2.0/16")
   #   p net1.include?(net2)     #=> true
   #   p net1.include?(net3)     #=> false
+  #   p net1.include?(net4)     #=> false
+  #   p net4.include?(net1)     #=> true
   def include?(other)
     other = coerce_other(other)
-    if ipv4_mapped?
-      if (@mask_addr >> 32) != 0xffffffffffffffffffffffff
-        return false
-      end
-      mask_addr = (@mask_addr & IN4MASK)
-      addr = (@addr & IN4MASK)
-      family = Socket::AF_INET
-    else
-      mask_addr = @mask_addr
-      addr = @addr
-      family = @family
-    end
-    if other.ipv4_mapped?
-      other_addr = (other.to_i & IN4MASK)
-      other_family = Socket::AF_INET
-    else
-      other_addr = other.to_i
-      other_family = other.family
-    end
-
-    if family != other_family
-      return false
-    end
-    return ((addr & mask_addr) == (other_addr & mask_addr))
+    return false unless other.family == family
+    begin_addr <= other.begin_addr && end_addr >= other.end_addr
   end
   alias === include?
 
@@ -213,7 +233,35 @@ class IPAddr
   # Returns a string containing the IP address representation in
   # canonical form.
   def to_string
-    return _to_string(@addr)
+    str = _to_string(@addr)
+
+    if @family == Socket::AF_INET6
+      str << zone_id.to_s
+    end
+
+    return str
+  end
+
+  # Returns a string containing the IP address representation with prefix.
+  def as_json(*)
+    if ipv4? && prefix == 32
+      to_s
+    elsif ipv6? && prefix == 128
+      to_s
+    else
+      cidr
+    end
+  end
+
+  # Returns a json string containing the IP address representation.
+  def to_json(*a)
+    %Q{"#{as_json(*a)}"}
+  end
+
+  # Returns a string containing the IP address representation in
+  # cidr notation
+  def cidr
+    "#{to_s}/#{prefix}"
   end
 
   # Returns a network byte ordered string form of the IP address.
@@ -226,7 +274,7 @@ class IPAddr
         (@addr >> (112 - 16 * i)) & 0xffff
       }.pack('n8')
     else
-      raise "unsupported address family"
+      raise AddressFamilyError, "unsupported address family"
     end
   end
 
@@ -240,6 +288,65 @@ class IPAddr
     return @family == Socket::AF_INET6
   end
 
+  # Returns true if the ipaddr is a loopback address.
+  # Loopback IPv4 addresses in the IPv4-mapped IPv6
+  # address range are also considered as loopback addresses.
+  def loopback?
+    case @family
+    when Socket::AF_INET
+      @addr & 0xff000000 == 0x7f000000 # 127.0.0.1/8
+    when Socket::AF_INET6
+      @addr == 1 || # ::1
+        (@addr >> 32 == 0xffff && (
+          @addr & 0xff000000 == 0x7f000000 # ::ffff:127.0.0.1/8
+        ))
+    else
+      raise AddressFamilyError, "unsupported address family"
+    end
+  end
+
+  # Returns true if the ipaddr is a private address.  IPv4 addresses
+  # in 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 as defined in RFC
+  # 1918 and IPv6 Unique Local Addresses in fc00::/7 as defined in RFC
+  # 4193 are considered private. Private IPv4 addresses in the
+  # IPv4-mapped IPv6 address range are also considered private.
+  def private?
+    case @family
+    when Socket::AF_INET
+      @addr & 0xff000000 == 0x0a000000 ||    # 10.0.0.0/8
+        @addr & 0xfff00000 == 0xac100000 ||  # 172.16.0.0/12
+        @addr & 0xffff0000 == 0xc0a80000     # 192.168.0.0/16
+    when Socket::AF_INET6
+      @addr & 0xfe00_0000_0000_0000_0000_0000_0000_0000 == 0xfc00_0000_0000_0000_0000_0000_0000_0000 ||
+        (@addr >> 32 == 0xffff && (
+          @addr & 0xff000000 == 0x0a000000 ||  # ::ffff:10.0.0.0/8
+          @addr & 0xfff00000 == 0xac100000 ||  # ::ffff:172.16.0.0/12
+          @addr & 0xffff0000 == 0xc0a80000     # ::ffff:192.168.0.0/16
+        ))
+    else
+      raise AddressFamilyError, "unsupported address family"
+    end
+  end
+
+  # Returns true if the ipaddr is a link-local address.  IPv4
+  # addresses in 169.254.0.0/16 reserved by RFC 3927 and link-local
+  # IPv6 Unicast Addresses in fe80::/10 reserved by RFC 4291 are
+  # considered link-local. Link-local IPv4 addresses in the
+  # IPv4-mapped IPv6 address range are also considered link-local.
+  def link_local?
+    case @family
+    when Socket::AF_INET
+      @addr & 0xffff0000 == 0xa9fe0000 # 169.254.0.0/16
+    when Socket::AF_INET6
+      @addr & 0xffc0_0000_0000_0000_0000_0000_0000_0000 == 0xfe80_0000_0000_0000_0000_0000_0000_0000 || # fe80::/10
+        (@addr >> 32 == 0xffff && (
+          @addr & 0xffff0000 == 0xa9fe0000 # ::ffff:169.254.0.0/16
+        ))
+    else
+      raise AddressFamilyError, "unsupported address family"
+    end
+  end
+
   # Returns true if the ipaddr is an IPv4-mapped IPv6 address.
   def ipv4_mapped?
     return ipv6? && (@addr >> 32) == 0xffff
@@ -247,6 +354,11 @@ class IPAddr
 
   # Returns true if the ipaddr is an IPv4-compatible IPv6 address.
   def ipv4_compat?
+    warn "IPAddr\##{__callee__} is obsolete", uplevel: 1 if $VERBOSE
+    _ipv4_compat?
+  end
+
+  def _ipv4_compat?             # :nodoc:
     if !ipv6? || (@addr >> 32) != 0
       return false
     end
@@ -254,29 +366,36 @@ class IPAddr
     return a != 0 && a != 1
   end
 
+  private :_ipv4_compat?
+
   # Returns a new ipaddr built by converting the native IPv4 address
   # into an IPv4-mapped IPv6 address.
   def ipv4_mapped
     if !ipv4?
-      raise ArgumentError, "not an IPv4 address"
+      raise InvalidAddressError, "not an IPv4 address: #{to_s}"
     end
-    return self.clone.set(@addr | 0xffff00000000, Socket::AF_INET6)
+    clone = self.clone.set(@addr | 0xffff00000000, Socket::AF_INET6)
+    clone.instance_variable_set(:@mask_addr, @mask_addr | 0xffffffffffffffffffffffff00000000)
+    clone
   end
 
   # Returns a new ipaddr built by converting the native IPv4 address
   # into an IPv4-compatible IPv6 address.
   def ipv4_compat
+    warn "IPAddr\##{__callee__} is obsolete", uplevel: 1 if $VERBOSE
     if !ipv4?
-      raise ArgumentError, "not an IPv4 address"
+      raise InvalidAddressError, "not an IPv4 address: #{to_s}"
     end
-    return self.clone.set(@addr, Socket::AF_INET6)
+    clone = self.clone.set(@addr, Socket::AF_INET6)
+    clone.instance_variable_set(:@mask_addr, @mask_addr | 0xffffffffffffffffffffffff00000000)
+    clone
   end
 
   # Returns a new ipaddr built by converting the IPv6 address into a
   # native IPv4 address.  If the IP address is not an IPv4-mapped or
   # IPv4-compatible IPv6 address, returns self.
   def native
-    if !ipv4_mapped? && !ipv4_compat?
+    if !ipv4_mapped? && !_ipv4_compat?
       return self
     end
     return self.clone.set(@addr & IN4MASK, Socket::AF_INET)
@@ -291,14 +410,14 @@ class IPAddr
     when Socket::AF_INET6
       return ip6_arpa
     else
-      raise "unsupported address family"
+      raise AddressFamilyError, "unsupported address family"
     end
   end
 
   # Returns a string for DNS reverse lookup compatible with RFC3172.
   def ip6_arpa
     if !ipv6?
-      raise ArgumentError, "not an IPv6 address"
+      raise InvalidAddressError, "not an IPv6 address: #{to_s}"
     end
     return _reverse + ".ip6.arpa"
   end
@@ -306,7 +425,7 @@ class IPAddr
   # Returns a string for DNS reverse lookup compatible with RFC1886.
   def ip6_int
     if !ipv6?
-      raise ArgumentError, "not an IPv6 address"
+      raise InvalidAddressError, "not an IPv6 address: #{to_s}"
     end
     return _reverse + ".ip6.int"
   end
@@ -319,10 +438,10 @@ class IPAddr
   # Compares the ipaddr with another.
   def <=>(other)
     other = coerce_other(other)
-
-    return nil if other.family != @family
-
-    return @addr <=> other.to_i
+  rescue
+    nil
+  else
+    @addr <=> other.to_i if other.family == @family
   end
   include Comparable
 
@@ -333,23 +452,41 @@ class IPAddr
 
   # Returns a hash value used by Hash, Set, and Array classes
   def hash
-    return ([@addr, @mask_addr].hash << 1) | (ipv4? ? 0 : 1)
+    return ([@addr, @mask_addr, @zone_id].hash << 1) | (ipv4? ? 0 : 1)
   end
 
   # Creates a Range object for the network address.
   def to_range
-    begin_addr = (@addr & @mask_addr)
+    self.class.new(begin_addr, @family)..self.class.new(end_addr, @family)
+  end
 
+  # Returns the prefix length in bits for the ipaddr.
+  def prefix
     case @family
     when Socket::AF_INET
-      end_addr = (@addr | (IN4MASK ^ @mask_addr))
+      n = IN4MASK ^ @mask_addr
+      i = 32
     when Socket::AF_INET6
-      end_addr = (@addr | (IN6MASK ^ @mask_addr))
+      n = IN6MASK ^ @mask_addr
+      i = 128
     else
-      raise "unsupported address family"
+      raise AddressFamilyError, "unsupported address family"
+    end
+    while n.positive?
+      n >>= 1
+      i -= 1
     end
+    i
+  end
 
-    return clone.set(begin_addr, @family)..clone.set(end_addr, @family)
+  # Sets the prefix length in bits
+  def prefix=(prefix)
+    case prefix
+    when Integer
+      mask!(prefix)
+    else
+      raise InvalidPrefixError, "prefix must be an integer"
+    end
   end
 
   # Returns a string containing a human-readable representation of the
@@ -360,14 +497,76 @@ class IPAddr
       af = "IPv4"
     when Socket::AF_INET6
       af = "IPv6"
+      zone_id = @zone_id.to_s
+    else
+      raise AddressFamilyError, "unsupported address family"
+    end
+    return sprintf("#<%s: %s:%s%s/%s>", self.class.name,
+                   af, _to_string(@addr), zone_id, _to_string(@mask_addr))
+  end
+
+  # Returns the netmask in string format e.g. 255.255.0.0
+  def netmask
+    _to_string(@mask_addr)
+  end
+
+  # Returns the wildcard mask in string format e.g. 0.0.255.255
+  def wildcard_mask
+    case @family
+    when Socket::AF_INET
+      mask = IN4MASK ^ @mask_addr
+    when Socket::AF_INET6
+      mask = IN6MASK ^ @mask_addr
+    else
+      raise AddressFamilyError, "unsupported address family"
+    end
+
+    _to_string(mask)
+  end
+
+  # Returns the IPv6 zone identifier, if present.
+  # Raises InvalidAddressError if not an IPv6 address.
+  def zone_id
+    if @family == Socket::AF_INET6
+      @zone_id
+    else
+      raise InvalidAddressError, "not an IPv6 address"
+    end
+  end
+
+  # Returns the IPv6 zone identifier, if present.
+  # Raises InvalidAddressError if not an IPv6 address.
+  def zone_id=(zid)
+    if @family == Socket::AF_INET6
+      case zid
+      when nil, /\A%(\w+)\z/
+        @zone_id = zid
+      else
+        raise InvalidAddressError, "invalid zone identifier for address"
+      end
     else
-      raise "unsupported address family"
+      raise InvalidAddressError, "not an IPv6 address"
     end
-    return sprintf("#<%s: %s:%s/%s>", self.class.name,
-                   af, _to_string(@addr), _to_string(@mask_addr))
   end
 
   protected
+  # :stopdoc:
+
+  def begin_addr
+    @addr & @mask_addr
+  end
+
+  def end_addr
+    case @family
+    when Socket::AF_INET
+      @addr | (IN4MASK ^ @mask_addr)
+    when Socket::AF_INET6
+      @addr | (IN6MASK ^ @mask_addr)
+    else
+      raise AddressFamilyError, "unsupported address family"
+    end
+  end
+  #:startdoc:
 
   # Set +@addr+, the internal stored ip address, to given +addr+. The
   # parameter +addr+ is validated using the first +family+ member,
@@ -376,33 +575,44 @@ class IPAddr
     case family[0] ? family[0] : @family
     when Socket::AF_INET
       if addr < 0 || addr > IN4MASK
-        raise ArgumentError, "invalid address"
+        raise InvalidAddressError, "invalid address: #{addr}"
       end
     when Socket::AF_INET6
       if addr < 0 || addr > IN6MASK
-        raise ArgumentError, "invalid address"
+        raise InvalidAddressError, "invalid address: #{addr}"
       end
     else
-      raise ArgumentError, "unsupported address family"
+      raise AddressFamilyError, "unsupported address family"
     end
     @addr = addr
     if family[0]
       @family = family[0]
+      if @family == Socket::AF_INET
+        @mask_addr &= IN4MASK
+      end
     end
     return self
   end
 
   # Set current netmask to given mask.
   def mask!(mask)
-    if mask.kind_of?(String)
-      if mask =~ /^\d+$/
+    case mask
+    when String
+      case mask
+      when /\A(0|[1-9]+\d*)\z/
         prefixlen = mask.to_i
+      when /\A\d+\z/
+        raise InvalidPrefixError, "leading zeros in prefix"
       else
         m = IPAddr.new(mask)
         if m.family != @family
-          raise ArgumentError, "address family is not same"
+          raise InvalidPrefixError, "address family is not same"
         end
         @mask_addr = m.to_i
+        n = @mask_addr ^ m.instance_variable_get(:@mask_addr)
+        unless ((n + 1) & n).zero?
+          raise InvalidPrefixError, "invalid mask #{mask}"
+        end
         @addr &= @mask_addr
         return self
       end
@@ -412,18 +622,18 @@ class IPAddr
     case @family
     when Socket::AF_INET
       if prefixlen < 0 || prefixlen > 32
-        raise ArgumentError, "invalid length"
+        raise InvalidPrefixError, "invalid length"
       end
       masklen = 32 - prefixlen
       @mask_addr = ((IN4MASK >> masklen) << masklen)
     when Socket::AF_INET6
       if prefixlen < 0 || prefixlen > 128
-        raise ArgumentError, "invalid length"
+        raise InvalidPrefixError, "invalid length"
       end
       masklen = 128 - prefixlen
       @mask_addr = ((IN6MASK >> masklen) << masklen)
     else
-      raise "unsupported address family"
+      raise AddressFamilyError, "unsupported address family"
     end
     @addr = ((@addr >> masklen) << masklen)
     return self
@@ -450,6 +660,7 @@ class IPAddr
   # those, such as &, |, include? and ==, accept a string, or a packed
   # in_addr value instead of an IPAddr object.
   def initialize(addr = '::', family = Socket::AF_UNSPEC)
+    @mask_addr = nil
     if !addr.kind_of?(String)
       case family
       when Socket::AF_INET, Socket::AF_INET6
@@ -457,14 +668,19 @@ class IPAddr
         @mask_addr = (family == Socket::AF_INET) ? IN4MASK : IN6MASK
         return
       when Socket::AF_UNSPEC
-        raise ArgumentError, "address family must be specified"
+        raise AddressFamilyError, "address family must be specified"
       else
-        raise ArgumentError, "unsupported address family: #{family}"
+        raise AddressFamilyError, "unsupported address family: #{family}"
       end
     end
-    prefix, prefixlen = addr.split('/')
-    if prefix =~ /^\[(.*)\]$/i
+    prefix, prefixlen = addr.split('/', 2)
+    if prefix =~ /\A\[(.*)\]\z/i
+      prefix = $1
+      family = Socket::AF_INET6
+    end
+    if prefix =~ /\A(.*)(%\w+)\z/
       prefix = $1
+      zone_id = $2
       family = Socket::AF_INET6
     end
     # It seems AI_NUMERICHOST doesn't do the job.
@@ -481,8 +697,9 @@ class IPAddr
       @addr = in6_addr(prefix)
       @family = Socket::AF_INET6
     end
+    @zone_id = zone_id
     if family != Socket::AF_UNSPEC && @family != family
-      raise ArgumentError, "address family mismatch"
+      raise AddressFamilyError, "address family mismatch"
     end
     if prefixlen
       mask!(prefixlen)
@@ -491,6 +708,7 @@ class IPAddr
     end
   end
 
+  # :stopdoc:
   def coerce_other(other)
     case other
     when IPAddr
@@ -507,12 +725,12 @@ class IPAddr
     when Array
       octets = addr
     else
-      m = RE_IPV4ADDRLIKE.match(addr) or return nil
-      octets = m.captures
+      RE_IPV4ADDRLIKE.match?(addr) or return nil
+      octets = addr.split('.')
     end
     octets.inject(0) { |i, s|
-      (n = s.to_i) < 256 or raise ArgumentError, "invalid address"
-      s.match(/\A0./) and raise ArgumentError, "zero-filled number is ambiguous"
+      (n = s.to_i) < 256 or raise InvalidAddressError, "invalid address: #{addr}"
+      (s != '0') && s.start_with?('0') and raise InvalidAddressError, "zero-filled number in IPv4 address is ambiguous: #{addr}"
       i << 8 | n
     }
   end
@@ -529,19 +747,19 @@ class IPAddr
       right = ''
     when RE_IPV6ADDRLIKE_COMPRESSED
       if $4
-        left.count(':') <= 6 or raise ArgumentError, "invalid address"
+        left.count(':') <= 6 or raise InvalidAddressError, "invalid address: #{left}"
         addr = in_addr($~[4,4])
         left = $1
         right = $3 + '0:0'
       else
         left.count(':') <= ($1.empty? || $2.empty? ? 8 : 7) or
-          raise InvalidAddressError, "invalid address"
+          raise InvalidAddressError, "invalid address: #{left}"
         left = $1
         right = $2
         addr = 0
       end
     else
-      raise ArgumentError, "invalid address"
+      raise InvalidAddressError, "invalid address: #{left}"
     end
     l = left.split(':')
     r = right.split(':')
@@ -561,7 +779,7 @@ class IPAddr
     when Socket::AF_INET6
       return addr & IN6MASK
     else
-      raise "unsupported address family"
+      raise AddressFamilyError, "unsupported address family"
     end
   end
 
@@ -574,7 +792,7 @@ class IPAddr
     when Socket::AF_INET6
       return ("%.32x" % @addr).reverse!.gsub!(/.(?!$)/, '\&.')
     else
-      raise "unsupported address family"
+      raise AddressFamilyError, "unsupported address family"
     end
   end
 
@@ -587,22 +805,22 @@ class IPAddr
     when Socket::AF_INET6
       return (("%.32x" % addr).gsub!(/.{4}(?!$)/, '\&:'))
     else
-      raise "unsupported address family"
+      raise AddressFamilyError, "unsupported address family"
     end
   end
 
 end
 
-unless Socket.const_defined? "AF_INET6"
+unless Socket.const_defined? :AF_INET6
   class Socket < BasicSocket
     # IPv6 protocol family
-    AF_INET6 = Object.new
+    AF_INET6 = Object.new.freeze
   end
 
   class << IPSocket
     private
 
-    def valid_v6?(addr)
+    def valid_v6?(addr) # :nodoc:
       case addr
       when IPAddr::RE_IPV6ADDRLIKE_FULL
         if $2
@@ -641,284 +859,3 @@ unless Socket.const_defined? "AF_INET6"
     end
   end
 end
-
-if $0 == __FILE__
-  eval DATA.read, nil, $0, __LINE__+4
-end
-
-__END__
-
-require 'test/unit'
-
-class TC_IPAddr < Test::Unit::TestCase
-  def test_s_new
-    [
-      ["3FFE:505:ffff::/48"],
-      ["0:0:0:1::"],
-      ["2001:200:300::/48"],
-      ["2001:200:300::192.168.1.2/48"],
-      ["1:2:3:4:5:6:7::"],
-      ["::2:3:4:5:6:7:8"],
-    ].each { |args|
-      assert_nothing_raised {
-        IPAddr.new(*args)
-      }
-    }
-
-    a = IPAddr.new
-    assert_equal("::", a.to_s)
-    assert_equal("0000:0000:0000:0000:0000:0000:0000:0000", a.to_string)
-    assert_equal(Socket::AF_INET6, a.family)
-
-    a = IPAddr.new("0123:4567:89ab:cdef:0ABC:DEF0:1234:5678")
-    assert_equal("123:4567:89ab:cdef:abc:def0:1234:5678", a.to_s)
-    assert_equal("0123:4567:89ab:cdef:0abc:def0:1234:5678", a.to_string)
-    assert_equal(Socket::AF_INET6, a.family)
-
-    a = IPAddr.new("3ffe:505:2::/48")
-    assert_equal("3ffe:505:2::", a.to_s)
-    assert_equal("3ffe:0505:0002:0000:0000:0000:0000:0000", a.to_string)
-    assert_equal(Socket::AF_INET6, a.family)
-    assert_equal(false, a.ipv4?)
-    assert_equal(true, a.ipv6?)
-    assert_equal("#<IPAddr: IPv6:3ffe:0505:0002:0000:0000:0000:0000:0000/ffff:ffff:ffff:0000:0000:0000:0000:0000>", a.inspect)
-
-    a = IPAddr.new("3ffe:505:2::/ffff:ffff:ffff::")
-    assert_equal("3ffe:505:2::", a.to_s)
-    assert_equal("3ffe:0505:0002:0000:0000:0000:0000:0000", a.to_string)
-    assert_equal(Socket::AF_INET6, a.family)
-
-    a = IPAddr.new("0.0.0.0")
-    assert_equal("0.0.0.0", a.to_s)
-    assert_equal("0.0.0.0", a.to_string)
-    assert_equal(Socket::AF_INET, a.family)
-
-    a = IPAddr.new("192.168.1.2")
-    assert_equal("192.168.1.2", a.to_s)
-    assert_equal("192.168.1.2", a.to_string)
-    assert_equal(Socket::AF_INET, a.family)
-    assert_equal(true, a.ipv4?)
-    assert_equal(false, a.ipv6?)
-
-    a = IPAddr.new("192.168.1.2/24")
-    assert_equal("192.168.1.0", a.to_s)
-    assert_equal("192.168.1.0", a.to_string)
-    assert_equal(Socket::AF_INET, a.family)
-    assert_equal("#<IPAddr: IPv4:192.168.1.0/255.255.255.0>", a.inspect)
-
-    a = IPAddr.new("192.168.1.2/255.255.255.0")
-    assert_equal("192.168.1.0", a.to_s)
-    assert_equal("192.168.1.0", a.to_string)
-    assert_equal(Socket::AF_INET, a.family)
-
-    assert_equal("0:0:0:1::", IPAddr.new("0:0:0:1::").to_s)
-    assert_equal("2001:200:300::", IPAddr.new("2001:200:300::/48").to_s)
-
-    assert_equal("2001:200:300::", IPAddr.new("[2001:200:300::]/48").to_s)
-    assert_equal("1:2:3:4:5:6:7:0", IPAddr.new("1:2:3:4:5:6:7::").to_s)
-    assert_equal("0:2:3:4:5:6:7:8", IPAddr.new("::2:3:4:5:6:7:8").to_s)
-
-    [
-      ["192.168.0.256"],
-      ["192.168.0.011"],
-      ["fe80::1%fxp0"],
-      ["::1/255.255.255.0"],
-      [IPAddr.new("::1").to_i],
-      ["::ffff:192.168.1.2/120", Socket::AF_INET],
-      ["[192.168.1.2]/120"],
-    ].each { |args|
-      assert_raises(ArgumentError) {
-        IPAddr.new(*args)
-      }
-    }
-  end
-
-  def test_s_new_ntoh
-    addr = ''
-    IPAddr.new("1234:5678:9abc:def0:1234:5678:9abc:def0").hton.each_byte { |c|
-      addr += sprintf("%02x", c)
-    }
-    assert_equal("123456789abcdef0123456789abcdef0", addr)
-    addr = ''
-    IPAddr.new("123.45.67.89").hton.each_byte { |c|
-      addr += sprintf("%02x", c)
-    }
-    assert_equal(sprintf("%02x%02x%02x%02x", 123, 45, 67, 89), addr)
-    a = IPAddr.new("3ffe:505:2::")
-    assert_equal("3ffe:505:2::", IPAddr.new_ntoh(a.hton).to_s)
-    a = IPAddr.new("192.168.2.1")
-    assert_equal("192.168.2.1", IPAddr.new_ntoh(a.hton).to_s)
-  end
-
-  def test_ipv4_compat
-    a = IPAddr.new("::192.168.1.2")
-    assert_equal("::192.168.1.2", a.to_s)
-    assert_equal("0000:0000:0000:0000:0000:0000:c0a8:0102", a.to_string)
-    assert_equal(Socket::AF_INET6, a.family)
-    assert_equal(true, a.ipv4_compat?)
-    b = a.native
-    assert_equal("192.168.1.2", b.to_s)
-    assert_equal(Socket::AF_INET, b.family)
-    assert_equal(false, b.ipv4_compat?)
-
-    a = IPAddr.new("192.168.1.2")
-    b = a.ipv4_compat
-    assert_equal("::192.168.1.2", b.to_s)
-    assert_equal(Socket::AF_INET6, b.family)
-  end
-
-  def test_ipv4_mapped
-    a = IPAddr.new("::ffff:192.168.1.2")
-    assert_equal("::ffff:192.168.1.2", a.to_s)
-    assert_equal("0000:0000:0000:0000:0000:ffff:c0a8:0102", a.to_string)
-    assert_equal(Socket::AF_INET6, a.family)
-    assert_equal(true, a.ipv4_mapped?)
-    b = a.native
-    assert_equal("192.168.1.2", b.to_s)
-    assert_equal(Socket::AF_INET, b.family)
-    assert_equal(false, b.ipv4_mapped?)
-
-    a = IPAddr.new("192.168.1.2")
-    b = a.ipv4_mapped
-    assert_equal("::ffff:192.168.1.2", b.to_s)
-    assert_equal(Socket::AF_INET6, b.family)
-  end
-
-  def test_reverse
-    assert_equal("f.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.2.0.0.0.5.0.5.0.e.f.f.3.ip6.arpa", IPAddr.new("3ffe:505:2::f").reverse)
-    assert_equal("1.2.168.192.in-addr.arpa", IPAddr.new("192.168.2.1").reverse)
-  end
-
-  def test_ip6_arpa
-    assert_equal("f.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.2.0.0.0.5.0.5.0.e.f.f.3.ip6.arpa", IPAddr.new("3ffe:505:2::f").ip6_arpa)
-    assert_raises(ArgumentError) {
-      IPAddr.new("192.168.2.1").ip6_arpa
-    }
-  end
-
-  def test_ip6_int
-    assert_equal("f.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.2.0.0.0.5.0.5.0.e.f.f.3.ip6.int", IPAddr.new("3ffe:505:2::f").ip6_int)
-    assert_raises(ArgumentError) {
-      IPAddr.new("192.168.2.1").ip6_int
-    }
-  end
-
-  def test_to_s
-    assert_equal("3ffe:0505:0002:0000:0000:0000:0000:0001", IPAddr.new("3ffe:505:2::1").to_string)
-    assert_equal("3ffe:505:2::1", IPAddr.new("3ffe:505:2::1").to_s)
-  end
-end
-
-class TC_Operator < Test::Unit::TestCase
-
-  IN6MASK32  = "ffff:ffff::"
-  IN6MASK128 = "ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff"
-
-  def setup
-    @in6_addr_any = IPAddr.new()
-    @a = IPAddr.new("3ffe:505:2::/48")
-    @b = IPAddr.new("0:0:0:1::")
-    @c = IPAddr.new(IN6MASK32)
-  end
-  alias set_up setup
-
-  def test_or
-    assert_equal("3ffe:505:2:1::", (@a | @b).to_s)
-    a = @a
-    a |= @b
-    assert_equal("3ffe:505:2:1::", a.to_s)
-    assert_equal("3ffe:505:2::", @a.to_s)
-    assert_equal("3ffe:505:2:1::",
-                 (@a | 0x00000000000000010000000000000000).to_s)
-  end
-
-  def test_and
-    assert_equal("3ffe:505::", (@a & @c).to_s)
-    a = @a
-    a &= @c
-    assert_equal("3ffe:505::", a.to_s)
-    assert_equal("3ffe:505:2::", @a.to_s)
-    assert_equal("3ffe:505::", (@a & 0xffffffff000000000000000000000000).to_s)
-  end
-
-  def test_shift_right
-    assert_equal("0:3ffe:505:2::", (@a >> 16).to_s)
-    a = @a
-    a >>= 16
-    assert_equal("0:3ffe:505:2::", a.to_s)
-    assert_equal("3ffe:505:2::", @a.to_s)
-  end
-
-  def test_shift_left
-    assert_equal("505:2::", (@a << 16).to_s)
-    a = @a
-    a <<= 16
-    assert_equal("505:2::", a.to_s)
-    assert_equal("3ffe:505:2::", @a.to_s)
-  end
-
-  def test_carrot
-    a = ~@in6_addr_any
-    assert_equal(IN6MASK128, a.to_s)
-    assert_equal("::", @in6_addr_any.to_s)
-  end
-
-  def test_equal
-    assert_equal(true, @a == IPAddr.new("3FFE:505:2::"))
-    assert_equal(true, @a == IPAddr.new("3ffe:0505:0002::"))
-    assert_equal(true, @a == IPAddr.new("3ffe:0505:0002:0:0:0:0:0"))
-    assert_equal(false, @a == IPAddr.new("3ffe:505:3::"))
-    assert_equal(true, @a != IPAddr.new("3ffe:505:3::"))
-    assert_equal(false, @a != IPAddr.new("3ffe:505:2::"))
-  end
-
-  def test_mask
-    a = @a.mask(32)
-    assert_equal("3ffe:505::", a.to_s)
-    assert_equal("3ffe:505:2::", @a.to_s)
-  end
-
-  def test_include?
-    assert_equal(true, @a.include?(IPAddr.new("3ffe:505:2::")))
-    assert_equal(true, @a.include?(IPAddr.new("3ffe:505:2::1")))
-    assert_equal(false, @a.include?(IPAddr.new("3ffe:505:3::")))
-    net1 = IPAddr.new("192.168.2.0/24")
-    assert_equal(true, net1.include?(IPAddr.new("192.168.2.0")))
-    assert_equal(true, net1.include?(IPAddr.new("192.168.2.255")))
-    assert_equal(false, net1.include?(IPAddr.new("192.168.3.0")))
-    # test with integer parameter
-    int = (192 << 24) + (168 << 16) + (2 << 8) + 13
-
-    assert_equal(true, net1.include?(int))
-    assert_equal(false, net1.include?(int+255))
-
-  end
-
-  def test_hash
-    a1 = IPAddr.new('192.168.2.0')
-    a2 = IPAddr.new('192.168.2.0')
-    a3 = IPAddr.new('3ffe:505:2::1')
-    a4 = IPAddr.new('3ffe:505:2::1')
-    a5 = IPAddr.new('127.0.0.1')
-    a6 = IPAddr.new('::1')
-    a7 = IPAddr.new('192.168.2.0/25')
-    a8 = IPAddr.new('192.168.2.0/25')
-
-    h = { a1 => 'ipv4', a2 => 'ipv4', a3 => 'ipv6', a4 => 'ipv6', a5 => 'ipv4', a6 => 'ipv6', a7 => 'ipv4', a8 => 'ipv4'}
-    assert_equal(5, h.size)
-    assert_equal('ipv4', h[a1])
-    assert_equal('ipv4', h[a2])
-    assert_equal('ipv6', h[a3])
-    assert_equal('ipv6', h[a4])
-
-    require 'set'
-    s = Set[a1, a2, a3, a4, a5, a6, a7, a8]
-    assert_equal(5, s.size)
-    assert_equal(true, s.include?(a1))
-    assert_equal(true, s.include?(a2))
-    assert_equal(true, s.include?(a3))
-    assert_equal(true, s.include?(a4))
-    assert_equal(true, s.include?(a5))
-    assert_equal(true, s.include?(a6))
-  end
-end
diff --git a/lib/irb.rb b/lib/irb.rb
deleted file mode 100644
index c8fa04c4e5..0000000000
--- a/lib/irb.rb
+++ /dev/null
@@ -1,352 +0,0 @@
-#
-#   irb.rb - irb main module
-#       $Release Version: 0.9.6 $
-#       $Revision$
-#       by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-require "e2mmap"
-
-require "irb/init"
-require "irb/context"
-require "irb/extend-command"
-#require "irb/workspace"
-
-require "irb/ruby-lex"
-require "irb/input-method"
-require "irb/locale"
-
-STDOUT.sync = true
-
-module IRB
-  @RCS_ID='-$Id$-'
-
-  class Abort < Exception;end
-
-  #
-  @CONF = {}
-
-  def IRB.conf
-    @CONF
-  end
-
-  # IRB version method
-  def IRB.version
-    if v = @CONF[:VERSION] then return v end
-
-    require "irb/version"
-    rv = @RELEASE_VERSION.sub(/\.0/, "")
-    @CONF[:VERSION] = format("irb %s(%s)", rv, @LAST_UPDATE_DATE)
-  end
-
-  def IRB.CurrentContext
-    IRB.conf[:MAIN_CONTEXT]
-  end
-
-  # initialize IRB and start TOP_LEVEL irb
-  def IRB.start(ap_path = nil)
-    $0 = File::basename(ap_path, ".rb") if ap_path
-
-    IRB.setup(ap_path)
-
-    if @CONF[:SCRIPT]
-      irb = Irb.new(nil, @CONF[:SCRIPT])
-    else
-      irb = Irb.new
-    end
-
-    @CONF[:IRB_RC].call(irb.context) if @CONF[:IRB_RC]
-    @CONF[:MAIN_CONTEXT] = irb.context
-
-    trap("SIGINT") do
-      irb.signal_handle
-    end
-
-    begin
-      catch(:IRB_EXIT) do
-        irb.eval_input
-      end
-    ensure
-      irb_at_exit
-    end
-#    print "\n"
-  end
-
-  def IRB.irb_at_exit
-    @CONF[:AT_EXIT].each{|hook| hook.call}
-  end
-
-  def IRB.irb_exit(irb, ret)
-    throw :IRB_EXIT, ret
-  end
-
-  def IRB.irb_abort(irb, exception = Abort)
-    if defined? Thread
-      irb.context.thread.raise exception, "abort then interrupt!"
-    else
-      raise exception, "abort then interrupt!"
-    end
-  end
-
-  #
-  # irb interpreter main routine
-  #
-  class Irb
-    def initialize(workspace = nil, input_method = nil, output_method = nil)
-      @context = Context.new(self, workspace, input_method, output_method)
-      @context.main.extend ExtendCommandBundle
-      @signal_status = :IN_IRB
-
-      @scanner = RubyLex.new
-      @scanner.exception_on_syntax_error = false
-    end
-    attr_reader :context
-    attr_accessor :scanner
-
-    def eval_input
-      @scanner.set_prompt do
-        |ltype, indent, continue, line_no|
-        if ltype
-          f = @context.prompt_s
-        elsif continue
-          f = @context.prompt_c
-        elsif indent > 0
-          f = @context.prompt_n
-        else
-          f = @context.prompt_i
-        end
-        f = "" unless f
-        if @context.prompting?
-          @context.io.prompt = p = prompt(f, ltype, indent, line_no)
-        else
-          @context.io.prompt = p = ""
-        end
-        if @context.auto_indent_mode
-          unless ltype
-            ind = prompt(@context.prompt_i, ltype, indent, line_no)[/.*\z/].size +
-              indent * 2 - p.size
-            ind += 2 if continue
-            @context.io.prompt = p + " " * ind if ind > 0
-          end
-        end
-      end
-
-      @scanner.set_input(@context.io) do
-        signal_status(:IN_INPUT) do
-          if l = @context.io.gets
-            print l if @context.verbose?
-          else
-            if @context.ignore_eof? and @context.io.readable_atfer_eof?
-              l = "\n"
-              if @context.verbose?
-                printf "Use \"exit\" to leave %s\n", @context.ap_name
-              end
-            else
-              print "\n"
-            end
-          end
-          l
-        end
-      end
-
-      @scanner.each_top_level_statement do |line, line_no|
-        signal_status(:IN_EVAL) do
-          begin
-            line.untaint
-            @context.evaluate(line, line_no)
-            output_value if @context.echo?
-            exc = nil
-          rescue Interrupt => exc
-          rescue SystemExit, SignalException
-            raise
-          rescue Exception => exc
-          end
-          if exc
-            print exc.class, ": ", exc, "\n"
-            if exc.backtrace[0] =~ /irb(2)?(\/.*|-.*|\.rb)?:/ && exc.class.to_s !~ /^IRB/ &&
-                !(SyntaxError === exc)
-              irb_bug = true
-            else
-              irb_bug = false
-            end
-
-            messages = []
-            lasts = []
-            levels = 0
-            for m in exc.backtrace
-              m = @context.workspace.filter_backtrace(m) unless irb_bug
-              if m
-                if messages.size < @context.back_trace_limit
-                  messages.push "\tfrom "+m
-                else
-                  lasts.push "\tfrom "+m
-                  if lasts.size > @context.back_trace_limit
-                    lasts.shift
-                    levels += 1
-                  end
-                end
-              end
-            end
-            print messages.join("\n"), "\n"
-            unless lasts.empty?
-              printf "... %d levels...\n", levels if levels > 0
-              print lasts.join("\n")
-            end
-            print "Maybe IRB bug!\n" if irb_bug
-          end
-          if $SAFE > 2
-            abort "Error: irb does not work for $SAFE level higher than 2"
-          end
-        end
-      end
-    end
-
-    def suspend_name(path = nil, name = nil)
-      @context.irb_path, back_path = path, @context.irb_path if path
-      @context.irb_name, back_name = name, @context.irb_name if name
-      begin
-        yield back_path, back_name
-      ensure
-        @context.irb_path = back_path if path
-        @context.irb_name = back_name if name
-      end
-    end
-
-    def suspend_workspace(workspace)
-      @context.workspace, back_workspace = workspace, @context.workspace
-      begin
-        yield back_workspace
-      ensure
-        @context.workspace = back_workspace
-      end
-    end
-
-    def suspend_input_method(input_method)
-      back_io = @context.io
-      @context.instance_eval{@io = input_method}
-      begin
-        yield back_io
-      ensure
-        @context.instance_eval{@io = back_io}
-      end
-    end
-
-    def suspend_context(context)
-      @context, back_context = context, @context
-      begin
-        yield back_context
-      ensure
-        @context = back_context
-      end
-    end
-
-    def signal_handle
-      unless @context.ignore_sigint?
-        print "\nabort!\n" if @context.verbose?
-        exit
-      end
-
-      case @signal_status
-      when :IN_INPUT
-        print "^C\n"
-        raise RubyLex::TerminateLineInput
-      when :IN_EVAL
-        IRB.irb_abort(self)
-      when :IN_LOAD
-        IRB.irb_abort(self, LoadAbort)
-      when :IN_IRB
-        # ignore
-      else
-        # ignore other cases as well
-      end
-    end
-
-    def signal_status(status)
-      return yield if @signal_status == :IN_LOAD
-
-      signal_status_back = @signal_status
-      @signal_status = status
-      begin
-        yield
-      ensure
-        @signal_status = signal_status_back
-      end
-    end
-
-    def prompt(prompt, ltype, indent, line_no)
-      p = prompt.dup
-      p.gsub!(/%([0-9]+)?([a-zA-Z])/) do
-        case $2
-        when "N"
-          @context.irb_name
-        when "m"
-          @context.main.to_s
-        when "M"
-          @context.main.inspect
-        when "l"
-          ltype
-        when "i"
-          if $1
-            format("%" + $1 + "d", indent)
-          else
-            indent.to_s
-          end
-        when "n"
-          if $1
-            format("%" + $1 + "d", line_no)
-          else
-            line_no.to_s
-          end
-        when "%"
-          "%"
-        end
-      end
-      p
-    end
-
-    def output_value
-      printf @context.return_format, @context.inspect_last_value
-    end
-
-    def inspect
-      ary = []
-      for iv in instance_variables
-        case (iv = iv.to_s)
-        when "@signal_status"
-          ary.push format("%s=:%s", iv, @signal_status.id2name)
-        when "@context"
-          ary.push format("%s=%s", iv, eval(iv).__to_s__)
-        else
-          ary.push format("%s=%s", iv, eval(iv))
-        end
-      end
-      format("#<%s: %s>", self.class, ary.join(", "))
-    end
-  end
-
-  # Singleton method
-  def @CONF.inspect
-    IRB.version unless self[:VERSION]
-
-    array = []
-    for k, v in sort{|a1, a2| a1[0].id2name <=> a2[0].id2name}
-      case k
-      when :MAIN_CONTEXT, :__TMP__EHV__
-        array.push format("CONF[:%s]=...myself...", k.id2name)
-      when :PROMPT
-        s = v.collect{
-          |kk, vv|
-          ss = vv.collect{|kkk, vvv| ":#{kkk.id2name}=>#{vvv.inspect}"}
-          format(":%s=>{%s}", kk.id2name, ss.join(", "))
-        }
-        array.push format("CONF[:%s]={%s}", k.id2name, s.join(", "))
-      else
-        array.push format("CONF[:%s]=%s", k.id2name, v.inspect)
-      end
-    end
-    array.join("\n")
-  end
-end
diff --git a/lib/irb/cmd/chws.rb b/lib/irb/cmd/chws.rb
deleted file mode 100644
index 65c977016b..0000000000
--- a/lib/irb/cmd/chws.rb
+++ /dev/null
@@ -1,32 +0,0 @@
-#
-#   change-ws.rb -
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-
-require "irb/cmd/nop.rb"
-require "irb/ext/change-ws.rb"
-
-module IRB
-  module ExtendCommand
-
-    class CurrentWorkingWorkspace<Nop
-      def execute(*obj)
-	irb_context.main
-      end
-    end
-
-    class ChangeWorkspace<Nop
-      def execute(*obj)
-	irb_context.change_workspace(*obj)
-	irb_context.main
-      end
-    end
-  end
-end
-
diff --git a/lib/irb/cmd/fork.rb b/lib/irb/cmd/fork.rb
deleted file mode 100644
index c2664626ae..0000000000
--- a/lib/irb/cmd/fork.rb
+++ /dev/null
@@ -1,38 +0,0 @@
-#
-#   fork.rb -
-#   	$Release Version: 0.9.6 $
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-
-@RCS_ID='-$Id$-'
-
-
-module IRB
-  module ExtendCommand
-    class Fork<Nop
-      def execute(&block)
-	pid = send ExtendCommand.irb_original_method_name("fork")
-	unless pid
-	  class << self
-	    alias_method :exit, ExtendCommand.irb_original_method_name('exit')
-	  end
-	  if iterator?
-	    begin
-	      yield
-	    ensure
-	      exit
-	    end
-	  end
-	end
-	pid
-      end
-    end
-  end
-end
-
-
diff --git a/lib/irb/cmd/help.rb b/lib/irb/cmd/help.rb
deleted file mode 100644
index 67cf89990b..0000000000
--- a/lib/irb/cmd/help.rb
+++ /dev/null
@@ -1,39 +0,0 @@
-#
-#   help.rb - helper using ri
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#
-# --
-#
-#
-#
-
-require 'rdoc/ri/driver'
-
-require "irb/cmd/nop.rb"
-
-module IRB
-  module ExtendCommand
-    class Help<Nop
-      begin
-        Ri = RDoc::RI::Driver.new
-      rescue SystemExit
-      else
-        def execute(*names)
-          if names.empty?
-            Ri.interactive
-            return
-          end
-          names.each do |name|
-            begin
-              Ri.display_name(name.to_s)
-            rescue RDoc::RI::Error
-              puts $!.message
-            end
-          end
-          nil
-        end
-      end
-    end
-  end
-end
diff --git a/lib/irb/cmd/load.rb b/lib/irb/cmd/load.rb
deleted file mode 100644
index 2a6de21ed7..0000000000
--- a/lib/irb/cmd/load.rb
+++ /dev/null
@@ -1,66 +0,0 @@
-#
-#   load.rb -
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-
-require "irb/cmd/nop.rb"
-require "irb/ext/loader"
-
-module IRB
-  module ExtendCommand
-    class Load<Nop
-      include IrbLoader
-
-      def execute(file_name, priv = nil)
-#	return ruby_load(file_name) unless IRB.conf[:USE_LOADER]
-	return irb_load(file_name, priv)
-      end
-    end
-
-    class Require<Nop
-      include IrbLoader
-
-      def execute(file_name)
-#	return ruby_require(file_name) unless IRB.conf[:USE_LOADER]
-
-	rex = Regexp.new("#{Regexp.quote(file_name)}(\.o|\.rb)?")
-	return false if $".find{|f| f =~ rex}
-
-	case file_name
-	when /\.rb$/
-	  begin
-	    if irb_load(file_name)
-	      $".push file_name
-	      return true
-	    end
-	  rescue LoadError
-	  end
-	when /\.(so|o|sl)$/
-	  return ruby_require(file_name)
-	end
-
-	begin
-	  irb_load(f = file_name + ".rb")
-	  $".push f
-	  return true
-	rescue LoadError
-	  return ruby_require(file_name)
-	end
-      end
-    end
-
-    class Source<Nop
-      include IrbLoader
-      def execute(file_name)
-	source_file(file_name)
-      end
-    end
-  end
-
-end
diff --git a/lib/irb/cmd/nop.rb b/lib/irb/cmd/nop.rb
deleted file mode 100644
index 2b028975c8..0000000000
--- a/lib/irb/cmd/nop.rb
+++ /dev/null
@@ -1,38 +0,0 @@
-#
-#   nop.rb -
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-module IRB
-  module ExtendCommand
-    class Nop
-
-      @RCS_ID='-$Id$-'
-
-      def self.execute(conf, *opts)
-	command = new(conf)
-	command.execute(*opts)
-      end
-
-      def initialize(conf)
-	@irb_context = conf
-      end
-
-      attr_reader :irb_context
-
-      def irb
-	@irb_context.irb
-      end
-
-      def execute(*opts)
-	#nop
-      end
-    end
-  end
-end
-
diff --git a/lib/irb/cmd/pushws.rb b/lib/irb/cmd/pushws.rb
deleted file mode 100644
index 5fd567731c..0000000000
--- a/lib/irb/cmd/pushws.rb
+++ /dev/null
@@ -1,38 +0,0 @@
-#
-#   change-ws.rb -
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-
-require "irb/cmd/nop.rb"
-require "irb/ext/workspaces.rb"
-
-module IRB
-  module ExtendCommand
-    class Workspaces<Nop
-      def execute(*obj)
-	irb_context.workspaces.collect{|ws| ws.main}
-      end
-    end
-
-    class PushWorkspace<Workspaces
-      def execute(*obj)
-	irb_context.push_workspace(*obj)
-	super
-      end
-    end
-
-    class PopWorkspace<Workspaces
-      def execute(*obj)
-	irb_context.pop_workspace(*obj)
-	super
-      end
-    end
-  end
-end
-
diff --git a/lib/irb/cmd/subirb.rb b/lib/irb/cmd/subirb.rb
deleted file mode 100644
index 4d54a72b6f..0000000000
--- a/lib/irb/cmd/subirb.rb
+++ /dev/null
@@ -1,40 +0,0 @@
-#   multi.rb -
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-
-require "irb/cmd/nop.rb"
-require "irb/ext/multi-irb"
-
-module IRB
-  module ExtendCommand
-    class IrbCommand<Nop
-      def execute(*obj)
-	IRB.irb(nil, *obj)
-      end
-    end
-
-    class Jobs<Nop
-      def execute
-	IRB.JobManager
-      end
-    end
-
-    class Foreground<Nop
-      def execute(key)
-	IRB.JobManager.switch(key)
-      end
-    end
-
-    class Kill<Nop
-      def execute(*keys)
-	IRB.JobManager.kill(*keys)
-      end
-    end
-  end
-end
diff --git a/lib/irb/completion.rb b/lib/irb/completion.rb
deleted file mode 100644
index 7fd69a0a09..0000000000
--- a/lib/irb/completion.rb
+++ /dev/null
@@ -1,233 +0,0 @@
-#
-#   irb/completor.rb -
-#   	$Release Version: 0.9$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ishitsuka.com)
-#       From Original Idea of shugo@ruby-lang.org
-#
-
-require "readline"
-
-module IRB
-  module InputCompletor
-
-    @RCS_ID='-$Id$-'
-
-    ReservedWords = [
-      "BEGIN", "END",
-      "alias", "and",
-      "begin", "break",
-      "case", "class",
-      "def", "defined", "do",
-      "else", "elsif", "end", "ensure",
-      "false", "for",
-      "if", "in",
-      "module",
-      "next", "nil", "not",
-      "or",
-      "redo", "rescue", "retry", "return",
-      "self", "super",
-      "then", "true",
-      "undef", "unless", "until",
-      "when", "while",
-      "yield",
-    ]
-
-    CompletionProc = proc { |input|
-      bind = IRB.conf[:MAIN_CONTEXT].workspace.binding
-
-#      puts "input: #{input}"
-
-      case input
-      when /^((["'`]).*\2)\.([^.]*)$/
-	# String
-	receiver = $1
-	message = $3
-
-	candidates = String.instance_methods.collect{|m| m.to_s}
-	select_message(receiver, message, candidates)
-
-      when /^(\/[^\/]*\/)\.([^.]*)$/
-	# Regexp
-	receiver = $1
-	message = Regexp.quote($2)
-
-	candidates = Regexp.instance_methods.collect{|m| m.to_s}
-	select_message(receiver, message, candidates)
-
-      when /^([^\]]*\])\.([^.]*)$/
-	# Array
-	receiver = $1
-	message = Regexp.quote($2)
-
-	candidates = Array.instance_methods.collect{|m| m.to_s}
-	select_message(receiver, message, candidates)
-
-      when /^([^\}]*\})\.([^.]*)$/
-	# Proc or Hash
-	receiver = $1
-	message = Regexp.quote($2)
-
-	candidates = Proc.instance_methods.collect{|m| m.to_s}
-	candidates |= Hash.instance_methods.collect{|m| m.to_s}
-	select_message(receiver, message, candidates)
-
-      when /^(:[^:.]*)$/
- 	# Symbol
-	if Symbol.respond_to?(:all_symbols)
-	  sym = $1
-	  candidates = Symbol.all_symbols.collect{|s| ":" + s.id2name}
-	  candidates.grep(/^#{sym}/)
-	else
-	  []
-	end
-
-      when /^::([A-Z][^:\.\(]*)$/
-	# Absolute Constant or class methods
-	receiver = $1
-	candidates = Object.constants.collect{|m| m.to_s}
-	candidates.grep(/^#{receiver}/).collect{|e| "::" + e}
-
-#      when /^(((::)?[A-Z][^:.\(]*)+)::?([^:.]*)$/
-      when /^([A-Z].*)::([^:.]*)$/
-	# Constant or class methods
-	receiver = $1
-	message = Regexp.quote($2)
-	begin
-	  candidates = eval("#{receiver}.constants.collect{|m| m.to_s}", bind)
-	  candidates |= eval("#{receiver}.methods.collect{|m| m.to_s}", bind)
-	rescue Exception
-	  candidates = []
-	end
-	select_message(receiver, message, candidates, "::")
-
-      when /^(:[^:.]+)(\.|::)([^.]*)$/
-	# Symbol
-	receiver = $1
-	sep = $2
-	message = Regexp.quote($3)
-
-	candidates = Symbol.instance_methods.collect{|m| m.to_s}
-	select_message(receiver, message, candidates, sep)
-
-      when /^(-?(0[dbo])?[0-9_]+(\.[0-9_]+)?([eE]-?[0-9]+)?)(\.|::)([^.]*)$/
-	# Numeric
-	receiver = $1
-	sep = $5
-	message = Regexp.quote($6)
-
-	begin
-	  candidates = eval(receiver, bind).methods.collect{|m| m.to_s}
-	rescue Exception
-	  candidates = []
-	end
-	select_message(receiver, message, candidates, sep)
-
-      when /^(-?0x[0-9a-fA-F_]+)(\.|::)([^.]*)$/
-	# Numeric(0xFFFF)
-	receiver = $1
-	sep = $2
-	message = Regexp.quote($3)
-
-	begin
-	  candidates = eval(receiver, bind).methods.collect{|m| m.to_s}
-	rescue Exception
-	  candidates = []
-	end
-	select_message(receiver, message, candidates, sep)
-
-      when /^(\$[^.]*)$/
-	# global var
-	regmessage = Regexp.new(Regexp.quote($1))
-	candidates = global_variables.collect{|m| m.to_s}.grep(regmessage)
-
-#      when /^(\$?(\.?[^.]+)+)\.([^.]*)$/
-#      when /^((\.?[^.]+)+)\.([^.]*)$/
-#      when /^([^."].*)\.([^.]*)$/
-      when /^([^."].*)(\.|::)([^.]*)$/
-	# variable.func or func.func
-	receiver = $1
-	sep = $2
-	message = Regexp.quote($3)
-
-	gv = eval("global_variables", bind).collect{|m| m.to_s}
-	lv = eval("local_variables", bind).collect{|m| m.to_s}
-	cv = eval("self.class.constants", bind).collect{|m| m.to_s}
-
-	if (gv | lv | cv).include?(receiver) or /^[A-Z]/ =~ receiver && /\./ !~ receiver
-	  # foo.func and foo is var. OR
-	  # foo::func and foo is var. OR
-	  # foo::Const and foo is var. OR
-	  # Foo::Bar.func
-	  begin
-	    candidates = []
-	    rec = eval(receiver, bind)
-	    if sep == "::" and rec.kind_of?(Module)
-	      candidates = rec.constants.collect{|m| m.to_s}
-	    end
-	    candidates |= rec.methods.collect{|m| m.to_s}
-	  rescue Exception
-	    candidates = []
-	  end
-	else
-	  # func1.func2
-	  candidates = []
-	  ObjectSpace.each_object(Module){|m|
-	    begin
-	      name = m.name
-	    rescue Exception
-	      name = ""
-	    end
-            begin
-              next if name != "IRB::Context" and
-                /^(IRB|SLex|RubyLex|RubyToken)/ =~ name
-            rescue Exception
-              next
-            end
-	    candidates.concat m.instance_methods(false).collect{|x| x.to_s}
-	  }
-	  candidates.sort!
-	  candidates.uniq!
-	end
-	select_message(receiver, message, candidates, sep)
-
-      when /^\.([^.]*)$/
-	# unknown(maybe String)
-
-	receiver = ""
-	message = Regexp.quote($1)
-
-	candidates = String.instance_methods(true).collect{|m| m.to_s}
-	select_message(receiver, message, candidates)
-
-      else
-	candidates = eval("methods | private_methods | local_variables | self.class.constants", bind).collect{|m| m.to_s}
-
-	(candidates|ReservedWords).grep(/^#{Regexp.quote(input)}/)
-      end
-    }
-
-    Operators = ["%", "&", "*", "**", "+",  "-",  "/",
-      "<", "<<", "<=", "<=>", "==", "===", "=~", ">", ">=", ">>",
-      "[]", "[]=", "^", "!", "!=", "!~"]
-
-    def self.select_message(receiver, message, candidates, sep = ".")
-      candidates.grep(/^#{message}/).collect do |e|
-	case e
-	when /^[a-zA-Z_]/
-	  receiver + sep + e
-	when /^[0-9]/
-	when *Operators
-	  #receiver + " " + e
-	end
-      end
-    end
-  end
-end
-
-if Readline.respond_to?("basic_word_break_characters=")
-#  Readline.basic_word_break_characters= " \t\n\"\\'`><=;|&{("
-  Readline.basic_word_break_characters= " \t\n`><=;|&{("
-end
-Readline.completion_append_character = nil
-Readline.completion_proc = IRB::InputCompletor::CompletionProc
diff --git a/lib/irb/context.rb b/lib/irb/context.rb
deleted file mode 100644
index 61b519170d..0000000000
--- a/lib/irb/context.rb
+++ /dev/null
@@ -1,295 +0,0 @@
-#
-#   irb/context.rb - irb context
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-require "irb/workspace"
-require "irb/inspector"
-
-module IRB
-  class Context
-    #
-    # Arguments:
-    #   input_method: nil -- stdin or readline
-    #		      String -- File
-    #		      other -- using this as InputMethod
-    #
-    def initialize(irb, workspace = nil, input_method = nil, output_method = nil)
-      @irb = irb
-      if workspace
-	@workspace = workspace
-      else
-	@workspace = WorkSpace.new
-      end
-      @thread = Thread.current if defined? Thread
-#      @irb_level = 0
-
-      # copy of default configuration
-      @ap_name = IRB.conf[:AP_NAME]
-      @rc = IRB.conf[:RC]
-      @load_modules = IRB.conf[:LOAD_MODULES]
-
-      @use_readline = IRB.conf[:USE_READLINE]
-      @verbose = IRB.conf[:VERBOSE]
-      @io = nil
-
-      self.inspect_mode = IRB.conf[:INSPECT_MODE]
-      self.math_mode = IRB.conf[:MATH_MODE] if IRB.conf[:MATH_MODE]
-      self.use_tracer = IRB.conf[:USE_TRACER] if IRB.conf[:USE_TRACER]
-      self.use_loader = IRB.conf[:USE_LOADER] if IRB.conf[:USE_LOADER]
-      self.eval_history = IRB.conf[:EVAL_HISTORY] if IRB.conf[:EVAL_HISTORY]
-
-      @ignore_sigint = IRB.conf[:IGNORE_SIGINT]
-      @ignore_eof = IRB.conf[:IGNORE_EOF]
-
-      @back_trace_limit = IRB.conf[:BACK_TRACE_LIMIT]
-
-      self.prompt_mode = IRB.conf[:PROMPT_MODE]
-
-      if IRB.conf[:SINGLE_IRB] or !defined?(JobManager)
-	@irb_name = IRB.conf[:IRB_NAME]
-      else
-	@irb_name = "irb#"+IRB.JobManager.n_jobs.to_s
-      end
-      @irb_path = "(" + @irb_name + ")"
-
-      case input_method
-      when nil
-	case use_readline?
-	when nil
-	  if (defined?(ReadlineInputMethod) && STDIN.tty? &&
-	      IRB.conf[:PROMPT_MODE] != :INF_RUBY)
-	    @io = ReadlineInputMethod.new
-	  else
-	    @io = StdioInputMethod.new
-	  end
-	when false
-	  @io = StdioInputMethod.new
-	when true
-	  if defined?(ReadlineInputMethod)
-	    @io = ReadlineInputMethod.new
-	  else
-	    @io = StdioInputMethod.new
-	  end
-	end
-
-      when String
-	@io = FileInputMethod.new(input_method)
-	@irb_name = File.basename(input_method)
-	@irb_path = input_method
-      else
-	@io = input_method
-      end
-      self.save_history = IRB.conf[:SAVE_HISTORY] if IRB.conf[:SAVE_HISTORY]
-
-      if output_method
-	@output_method = output_method
-      else
-	@output_method = StdioOutputMethod.new
-      end
-
-      @echo = IRB.conf[:ECHO]
-      if @echo.nil?
-	@echo = true
-      end
-      @debug_level = IRB.conf[:DEBUG_LEVEL]
-    end
-
-    def main
-      @workspace.main
-    end
-
-    attr_reader :workspace_home
-    attr_accessor :workspace
-    attr_reader :thread
-    attr_accessor :io
-
-    attr_accessor :irb
-    attr_accessor :ap_name
-    attr_accessor :rc
-    attr_accessor :load_modules
-    attr_accessor :irb_name
-    attr_accessor :irb_path
-
-    attr_reader :use_readline
-    attr_reader :inspect_mode
-
-    attr_reader :prompt_mode
-    attr_accessor :prompt_i
-    attr_accessor :prompt_s
-    attr_accessor :prompt_c
-    attr_accessor :prompt_n
-    attr_accessor :auto_indent_mode
-    attr_accessor :return_format
-
-    attr_accessor :ignore_sigint
-    attr_accessor :ignore_eof
-    attr_accessor :echo
-    attr_accessor :verbose
-    attr_reader :debug_level
-
-    attr_accessor :back_trace_limit
-
-    alias use_readline? use_readline
-    alias rc? rc
-    alias ignore_sigint? ignore_sigint
-    alias ignore_eof? ignore_eof
-    alias echo? echo
-
-    def verbose?
-      if @verbose.nil?
-	if defined?(ReadlineInputMethod) && @io.kind_of?(ReadlineInputMethod)
-	  false
-	elsif !STDIN.tty? or @io.kind_of?(FileInputMethod)
-	  true
-	else
-	  false
-	end
-      else
-	@verbose
-      end
-    end
-
-    def prompting?
-      verbose? || (STDIN.tty? && @io.kind_of?(StdioInputMethod) ||
-		(defined?(ReadlineInputMethod) && @io.kind_of?(ReadlineInputMethod)))
-    end
-
-    attr_reader :last_value
-
-    def set_last_value(value)
-      @last_value = value
-      @workspace.evaluate self, "_ = IRB.CurrentContext.last_value"
-    end
-
-    def prompt_mode=(mode)
-      @prompt_mode = mode
-      pconf = IRB.conf[:PROMPT][mode]
-      @prompt_i = pconf[:PROMPT_I]
-      @prompt_s = pconf[:PROMPT_S]
-      @prompt_c = pconf[:PROMPT_C]
-      @prompt_n = pconf[:PROMPT_N]
-      @return_format = pconf[:RETURN]
-      if ai = pconf.include?(:AUTO_INDENT)
-	@auto_indent_mode = ai
-      else
-	@auto_indent_mode = IRB.conf[:AUTO_INDENT]
-      end
-    end
-
-    def inspect?
-      @inspect_mode.nil? or @inspect_mode
-    end
-
-    def file_input?
-      @io.class == FileInputMethod
-    end
-
-    def inspect_mode=(opt)
-
-      if i = INSPECTORS[opt]
-	@inspect_mode = opt
-	@inspect_method = i
-	i.init
-      else
-	case opt
-	when nil
-	  if INSPECTORS.keys_with_inspector(INSPECTORS[true]).include?(@inspect_mode)
-	    self.inspect_mode = false
-	  elsif INSPECTORS.keys_with_inspector(INSPECTORS[false]).include?(@inspect_mode)
-	    self.inspect_mode = true
-	  else
-	    puts "Can't switch inspect mode."
-	    return
-	  end
-	when /^\s*\{.*\}\s*$/
-	  begin
-	    inspector = eval "proc#{opt}"
-	  rescue Exception
-	    puts "Can't switch inspect mode(#{opt})."
-	    return
-	  end
-	  self.inspect_mode = inspector
-	when Proc
-	  self.inspect_mode = IRB::Inspector(opt)
-	when Inspector
-	  prefix = "usr%d"
-	  i = 1
-	  while INSPECTORS[format(prefix, i)]; i += 1; end
-	  @inspect_mode = format(prefix, i)
-	  @inspect_method = opt
-	  INSPECTORS.def_inspector(format(prefix, i), @inspect_method)
-	else
-	  puts "Can't switch inspect mode(#{opt})."
-	  return
-	end
-      end
-      print "Switch to#{unless @inspect_mode; ' non';end} inspect mode.\n" if verbose?
-      @inspect_mode
-    end
-
-
-    def use_readline=(opt)
-      @use_readline = opt
-      print "use readline module\n" if @use_readline
-    end
-
-    def debug_level=(value)
-      @debug_level = value
-      RubyLex.debug_level = value
-      SLex.debug_level = value
-    end
-
-    def debug?
-      @debug_level > 0
-    end
-
-    def evaluate(line, line_no)
-      @line_no = line_no
-      set_last_value(@workspace.evaluate(self, line, irb_path, line_no))
-#      @workspace.evaluate("_ = IRB.conf[:MAIN_CONTEXT]._")
-#      @_ = @workspace.evaluate(line, irb_path, line_no)
-    end
-
-    def inspect_last_value
-      @inspect_method.inspect_value(@last_value)
-    end
-
-    alias __exit__ exit
-    def exit(ret = 0)
-      IRB.irb_exit(@irb, ret)
-    end
-
-    NOPRINTING_IVARS = ["@last_value"]
-    NO_INSPECTING_IVARS = ["@irb", "@io"]
-    IDNAME_IVARS = ["@prompt_mode"]
-
-    alias __inspect__ inspect
-    def inspect
-      array = []
-      for ivar in instance_variables.sort{|e1, e2| e1 <=> e2}
-	ivar = ivar.to_s
-	name = ivar.sub(/^@(.*)$/, '\1')
-	val = instance_eval(ivar)
-	case ivar
-	when *NOPRINTING_IVARS
-	  array.push format("conf.%s=%s", name, "...")
-	when *NO_INSPECTING_IVARS
-	  array.push format("conf.%s=%s", name, val.to_s)
-	when *IDNAME_IVARS
-	  array.push format("conf.%s=:%s", name, val.id2name)
-	else
-	  array.push format("conf.%s=%s", name, val.inspect)
-	end
-      end
-      array.join("\n")
-    end
-    alias __to_s__ to_s
-    alias to_s inspect
-  end
-end
diff --git a/lib/irb/ext/change-ws.rb b/lib/irb/ext/change-ws.rb
deleted file mode 100644
index dea969d384..0000000000
--- a/lib/irb/ext/change-ws.rb
+++ /dev/null
@@ -1,61 +0,0 @@
-#
-#   irb/ext/cb.rb -
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-
-module IRB
-  class Context
-
-    def home_workspace
-      if defined? @home_workspace
-	@home_workspace
-      else
-	@home_workspace = @workspace
-      end
-    end
-
-    def change_workspace(*_main)
-      if _main.empty?
-	@workspace = home_workspace
-	return main
-      end
-
-      @workspace = WorkSpace.new(_main[0])
-
-      if !(class<<main;ancestors;end).include?(ExtendCommandBundle)
-	main.extend ExtendCommandBundle
-      end
-    end
-
-#     def change_binding(*_main)
-#       back = @workspace
-#       @workspace = WorkSpace.new(*_main)
-#       unless _main.empty?
-# 	begin
-# 	  main.extend ExtendCommandBundle
-# 	rescue
-# 	  print "can't change binding to: ", main.inspect, "\n"
-# 	  @workspace = back
-# 	  return nil
-# 	end
-#       end
-#       @irb_level += 1
-#       begin
-# 	catch(:SU_EXIT) do
-# 	  @irb.eval_input
-# 	end
-#       ensure
-# 	@irb_level -= 1
-#  	@workspace = back
-#       end
-#     end
-#     alias change_workspace change_binding
-  end
-end
-
diff --git a/lib/irb/ext/history.rb b/lib/irb/ext/history.rb
deleted file mode 100644
index 1495f9eb14..0000000000
--- a/lib/irb/ext/history.rb
+++ /dev/null
@@ -1,109 +0,0 @@
-#
-#   history.rb -
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-
-module IRB
-
-  class Context
-
-    NOPRINTING_IVARS.push "@eval_history_values"
-
-    alias _set_last_value set_last_value
-
-    def set_last_value(value)
-      _set_last_value(value)
-
-#      @workspace.evaluate self, "_ = IRB.CurrentContext.last_value"
-      if @eval_history #and !@eval_history_values.equal?(llv)
- 	@eval_history_values.push @line_no, @last_value
- 	@workspace.evaluate self, "__ = IRB.CurrentContext.instance_eval{@eval_history_values}"
-      end
-
-      @last_value
-    end
-
-    attr_reader :eval_history
-    def eval_history=(no)
-      if no
-	if defined?(@eval_history) && @eval_history
-	  @eval_history_values.size(no)
-	else
-	  @eval_history_values = History.new(no)
-	  IRB.conf[:__TMP__EHV__] = @eval_history_values
-	  @workspace.evaluate(self, "__ = IRB.conf[:__TMP__EHV__]")
-	  IRB.conf.delete(:__TMP_EHV__)
-	end
-      else
-	@eval_history_values = nil
-      end
-      @eval_history = no
-    end
-  end
-
-  class History
-    @RCS_ID='-$Id$-'
-
-    def initialize(size = 16)
-      @size = size
-      @contents = []
-    end
-
-    def size(size)
-      if size != 0 && size < @size
-	@contents = @contents[@size - size .. @size]
-      end
-      @size = size
-    end
-
-    def [](idx)
-      begin
-	if idx >= 0
-	  @contents.find{|no, val| no == idx}[1]
-	else
-	  @contents[idx][1]
-	end
-      rescue NameError
-	nil
-      end
-    end
-
-    def push(no, val)
-      @contents.push [no, val]
-      @contents.shift if @size != 0 && @contents.size > @size
-    end
-
-    alias real_inspect inspect
-
-    def inspect
-      if @contents.empty?
-	return real_inspect
-      end
-
-      unless (last = @contents.pop)[1].equal?(self)
-	@contents.push last
-	last = nil
-      end
-      str = @contents.collect{|no, val|
-	if val.equal?(self)
-	  "#{no} ...self-history..."
-	else
-	  "#{no} #{val.inspect}"
-	end
-      }.join("\n")
-      if str == ""
-	str = "Empty."
-      end
-      @contents.push last if last
-      str
-    end
-  end
-end
-
-
diff --git a/lib/irb/ext/loader.rb b/lib/irb/ext/loader.rb
deleted file mode 100644
index 26a3203676..0000000000
--- a/lib/irb/ext/loader.rb
+++ /dev/null
@@ -1,119 +0,0 @@
-#
-#   loader.rb -
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-
-
-module IRB
-  class LoadAbort < Exception;end
-
-  module IrbLoader
-    @RCS_ID='-$Id$-'
-
-    alias ruby_load load
-    alias ruby_require require
-
-    def irb_load(fn, priv = nil)
-      path = search_file_from_ruby_path(fn)
-      raise LoadError, "No such file to load -- #{fn}" unless path
-
-      load_file(path, priv)
-    end
-
-    def search_file_from_ruby_path(fn)
-      if /^#{Regexp.quote(File::Separator)}/ =~ fn
-	return fn if File.exist?(fn)
-	return nil
-      end
-
-      for path in $:
-	if File.exist?(f = File.join(path, fn))
-	  return f
-	end
-      end
-      return nil
-    end
-
-    def source_file(path)
-      irb.suspend_name(path, File.basename(path)) do
-	irb.suspend_input_method(FileInputMethod.new(path)) do
-	  |back_io|
-	  irb.signal_status(:IN_LOAD) do
-	    if back_io.kind_of?(FileInputMethod)
-	      irb.eval_input
-	    else
-	      begin
-		irb.eval_input
-	      rescue LoadAbort
-		print "load abort!!\n"
-	      end
-	    end
-	  end
-	end
-      end
-    end
-
-    def load_file(path, priv = nil)
-      irb.suspend_name(path, File.basename(path)) do
-
-	if priv
-	  ws = WorkSpace.new(Module.new)
-	else
-	  ws = WorkSpace.new
-	end
-	irb.suspend_workspace(ws) do
-	  irb.suspend_input_method(FileInputMethod.new(path)) do
-	    |back_io|
-	    irb.signal_status(:IN_LOAD) do
-#	      p irb.conf
-	      if back_io.kind_of?(FileInputMethod)
-		irb.eval_input
-	      else
-		begin
-		  irb.eval_input
-		rescue LoadAbort
-		  print "load abort!!\n"
-		end
-	      end
-	    end
-	  end
-	end
-      end
-    end
-
-    def old
-      back_io = @io
-      back_path = @irb_path
-      back_name = @irb_name
-      back_scanner = @irb.scanner
-      begin
- 	@io = FileInputMethod.new(path)
- 	@irb_name = File.basename(path)
-	@irb_path = path
-	@irb.signal_status(:IN_LOAD) do
-	  if back_io.kind_of?(FileInputMethod)
-	    @irb.eval_input
-	  else
-	    begin
-	      @irb.eval_input
-	    rescue LoadAbort
-	      print "load abort!!\n"
-	    end
-	  end
-	end
-      ensure
- 	@io = back_io
- 	@irb_name = back_name
- 	@irb_path = back_path
-	@irb.scanner = back_scanner
-      end
-    end
-  end
-end
-
diff --git a/lib/irb/ext/math-mode.rb b/lib/irb/ext/math-mode.rb
deleted file mode 100644
index 41be79841c..0000000000
--- a/lib/irb/ext/math-mode.rb
+++ /dev/null
@@ -1,36 +0,0 @@
-#
-#   math-mode.rb -
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-require "mathn"
-
-module IRB
-  class Context
-    attr_reader :math_mode
-    alias math? math_mode
-
-    def math_mode=(opt)
-      if @math_mode == true && opt == false
-	IRB.fail CantReturnToNormalMode
-	return
-      end
-
-      @math_mode = opt
-      if math_mode
-	main.extend Math
-	print "start math mode\n" if verbose?
-      end
-    end
-
-    def inspect?
-      @inspect_mode.nil? && !@math_mode or @inspect_mode
-    end
-  end
-end
-
diff --git a/lib/irb/ext/multi-irb.rb b/lib/irb/ext/multi-irb.rb
deleted file mode 100644
index a8475b75cd..0000000000
--- a/lib/irb/ext/multi-irb.rb
+++ /dev/null
@@ -1,242 +0,0 @@
-#
-#   irb/multi-irb.rb - multiple irb module
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-IRB.fail CantShiftToMultiIrbMode unless defined?(Thread)
-require "thread"
-
-module IRB
-  # job management class
-  class JobManager
-    @RCS_ID='-$Id$-'
-
-    def initialize
-      # @jobs = [[thread, irb],...]
-      @jobs = []
-      @current_job = nil
-    end
-
-    attr_accessor :current_job
-
-    def n_jobs
-      @jobs.size
-    end
-
-    def thread(key)
-      th, = search(key)
-      th
-    end
-
-    def irb(key)
-      _, irb = search(key)
-      irb
-    end
-
-    def main_thread
-      @jobs[0][0]
-    end
-
-    def main_irb
-      @jobs[0][1]
-    end
-
-    def insert(irb)
-      @jobs.push [Thread.current, irb]
-    end
-
-    def switch(key)
-      th, irb = search(key)
-      IRB.fail IrbAlreadyDead unless th.alive?
-      IRB.fail IrbSwitchedToCurrentThread if th == Thread.current
-      @current_job = irb
-      th.run
-      Thread.stop
-      @current_job = irb(Thread.current)
-    end
-
-    def kill(*keys)
-      for key in keys
-	th, _ = search(key)
-	IRB.fail IrbAlreadyDead unless th.alive?
-	th.exit
-      end
-    end
-
-    def search(key)
-      job = case key
-      when Integer
-	@jobs[key]
-      when Irb
-	@jobs.find{|k, v| v.equal?(key)}
-      when Thread
-	@jobs.assoc(key)
-      else
-	@jobs.find{|k, v| v.context.main.equal?(key)}
-      end
-      IRB.fail NoSuchJob, key if job.nil?
-      job
-    end
-
-    def delete(key)
-      case key
-      when Integer
-	IRB.fail NoSuchJob, key unless @jobs[key]
-	@jobs[key] = nil
-      else
-	catch(:EXISTS) do
-	  @jobs.each_index do
-	    |i|
-	    if @jobs[i] and (@jobs[i][0] == key ||
-			     @jobs[i][1] == key ||
-			     @jobs[i][1].context.main.equal?(key))
-	      @jobs[i] = nil
-	      throw :EXISTS
-	    end
-	  end
-	  IRB.fail NoSuchJob, key
-	end
-      end
-      until assoc = @jobs.pop; end unless @jobs.empty?
-      @jobs.push assoc
-    end
-
-    def inspect
-      ary = []
-      @jobs.each_index do
-	|i|
-	th, irb = @jobs[i]
-	next if th.nil?
-
-	if th.alive?
-	  if th.stop?
-	    t_status = "stop"
-	  else
-	    t_status = "running"
-	  end
-	else
-	  t_status = "exited"
-	end
-	ary.push format("#%d->%s on %s (%s: %s)",
-			i,
-			irb.context.irb_name,
-			irb.context.main,
-			th,
-			t_status)
-      end
-      ary.join("\n")
-    end
-  end
-
-  @JobManager = JobManager.new
-
-  def IRB.JobManager
-    @JobManager
-  end
-
-  def IRB.CurrentContext
-    IRB.JobManager.irb(Thread.current).context
-  end
-
-  # invoke multi-irb
-  def IRB.irb(file = nil, *main)
-    workspace = WorkSpace.new(*main)
-    parent_thread = Thread.current
-    Thread.start do
-      begin
-	irb = Irb.new(workspace, file)
-      rescue
-	print "Subirb can't start with context(self): ", workspace.main.inspect, "\n"
-	print "return to main irb\n"
-	Thread.pass
-	Thread.main.wakeup
-	Thread.exit
-      end
-      @CONF[:IRB_RC].call(irb.context) if @CONF[:IRB_RC]
-      @JobManager.insert(irb)
-      @JobManager.current_job = irb
-      begin
-	system_exit = false
-	catch(:IRB_EXIT) do
-	  irb.eval_input
-	end
-      rescue SystemExit
-	system_exit = true
-	raise
-	#fail
-      ensure
-	unless system_exit
-	  @JobManager.delete(irb)
-	  if @JobManager.current_job == irb
-	    if parent_thread.alive?
-	      @JobManager.current_job = @JobManager.irb(parent_thread)
-	      parent_thread.run
-	    else
-	      @JobManager.current_job = @JobManager.main_irb
-	      @JobManager.main_thread.run
-	    end
-	  end
-	end
-      end
-    end
-    Thread.stop
-    @JobManager.current_job = @JobManager.irb(Thread.current)
-  end
-
-#   class Context
-#     def set_last_value(value)
-#       @last_value = value
-#       @workspace.evaluate "_ = IRB.JobManager.irb(Thread.current).context.last_value"
-#       if @eval_history #and !@__.equal?(@last_value)
-# 	@eval_history_values.push @line_no, @last_value
-# 	@workspace.evaluate "__ = IRB.JobManager.irb(Thread.current).context.instance_eval{@eval_history_values}"
-#       end
-#       @last_value
-#     end
-#   end
-
-#  module ExtendCommand
-#     def irb_context
-#       IRB.JobManager.irb(Thread.current).context
-#     end
-# #    alias conf irb_context
-#   end
-
-  @CONF[:SINGLE_IRB_MODE] = false
-  @JobManager.insert(@CONF[:MAIN_CONTEXT].irb)
-  @JobManager.current_job = @CONF[:MAIN_CONTEXT].irb
-
-  class Irb
-    def signal_handle
-      unless @context.ignore_sigint?
-	print "\nabort!!\n" if @context.verbose?
-	exit
-      end
-
-      case @signal_status
-      when :IN_INPUT
-	print "^C\n"
-	IRB.JobManager.thread(self).raise RubyLex::TerminateLineInput
-      when :IN_EVAL
-	IRB.irb_abort(self)
-      when :IN_LOAD
-	IRB.irb_abort(self, LoadAbort)
-      when :IN_IRB
-	# ignore
-      else
-	# ignore other cases as well
-      end
-    end
-  end
-
-  trap("SIGINT") do
-    @JobManager.current_job.signal_handle
-    Thread.stop
-  end
-
-end
diff --git a/lib/irb/ext/save-history.rb b/lib/irb/ext/save-history.rb
deleted file mode 100644
index f9c983ac11..0000000000
--- a/lib/irb/ext/save-history.rb
+++ /dev/null
@@ -1,97 +0,0 @@
-#   save-history.rb -
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-
-require "readline"
-
-module IRB
-  module HistorySavingAbility
-    @RCS_ID='-$Id$-'
-  end
-
-  class Context
-    def init_save_history
-      unless (class<<@io;self;end).include?(HistorySavingAbility)
-	@io.extend(HistorySavingAbility)
-      end
-    end
-
-    def save_history
-      IRB.conf[:SAVE_HISTORY]
-    end
-
-    def save_history=(val)
-      IRB.conf[:SAVE_HISTORY] = val
-      if val
-	main_context = IRB.conf[:MAIN_CONTEXT]
-	main_context = self unless main_context
-	main_context.init_save_history
-      end
-    end
-
-    def history_file
-      IRB.conf[:HISTORY_FILE]
-    end
-
-    def history_file=(hist)
-      IRB.conf[:HISTORY_FILE] = hist
-    end
-  end
-
-  module HistorySavingAbility
-    include Readline
-
-#     def HistorySavingAbility.create_finalizer
-#       proc do
-# 	if num = IRB.conf[:SAVE_HISTORY] and (num = num.to_i) > 0
-# 	  if hf = IRB.conf[:HISTORY_FILE]
-# 	    file = File.expand_path(hf)
-# 	  end
-# 	  file = IRB.rc_file("_history") unless file
-# 	  open(file, 'w' ) do |f|
-# 	    hist = HISTORY.to_a
-# 	    f.puts(hist[-num..-1] || hist)
-# 	  end
-# 	end
-#       end
-#     end
-
-    def HistorySavingAbility.extended(obj)
-#      ObjectSpace.define_finalizer(obj, HistorySavingAbility.create_finalizer)
-      IRB.conf[:AT_EXIT].push proc{obj.save_history}
-      obj.load_history
-      obj
-    end
-
-    def load_history
-      if history_file = IRB.conf[:HISTORY_FILE]
-	history_file = File.expand_path(history_file)
-      end
-      history_file = IRB.rc_file("_history") unless history_file
-      if File.exist?(history_file)
-	open(history_file) do |f|
-	  f.each {|l| HISTORY << l.chomp}
-	end
-      end
-    end
-
-    def save_history
-      if num = IRB.conf[:SAVE_HISTORY] and (num = num.to_i) > 0
-	if history_file = IRB.conf[:HISTORY_FILE]
-	  history_file = File.expand_path(history_file)
-	end
-	history_file = IRB.rc_file("_history") unless history_file
-	open(history_file, 'w' ) do |f|
-	  hist = HISTORY.to_a
-	  f.puts(hist[-num..-1] || hist)
-	end
-      end
-    end
-  end
-end
diff --git a/lib/irb/ext/tracer.rb b/lib/irb/ext/tracer.rb
deleted file mode 100644
index 46a9d53a2e..0000000000
--- a/lib/irb/ext/tracer.rb
+++ /dev/null
@@ -1,60 +0,0 @@
-#
-#   irb/lib/tracer.rb -
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-require "tracer"
-
-module IRB
-
-  # initialize tracing function
-  def IRB.initialize_tracer
-    Tracer.verbose = false
-    Tracer.add_filter {
-      |event, file, line, id, binding, *rests|
-      /^#{Regexp.quote(@CONF[:IRB_LIB_PATH])}/ !~ file and
-	File::basename(file) != "irb.rb"
-    }
-  end
-
-  class Context
-    attr_reader :use_tracer
-    alias use_tracer? use_tracer
-
-    def use_tracer=(opt)
-      if opt
-	Tracer.set_get_line_procs(@irb_path) {
-	  |line_no, *rests|
-	  @io.line(line_no)
-	}
-      elsif !opt && @use_tracer
-	Tracer.off
-      end
-      @use_tracer=opt
-    end
-  end
-
-  class WorkSpace
-    alias __evaluate__ evaluate
-    def evaluate(context, statements, file = nil, line = nil)
-      if context.use_tracer? && file != nil && line != nil
-	Tracer.on
-	begin
-	  __evaluate__(context, statements, file, line)
-	ensure
-	  Tracer.off
-	end
-      else
-	__evaluate__(context, statements, file || __FILE__, line || __LINE__)
-      end
-    end
-  end
-
-  IRB.initialize_tracer
-end
-
diff --git a/lib/irb/ext/use-loader.rb b/lib/irb/ext/use-loader.rb
deleted file mode 100644
index 64283b8989..0000000000
--- a/lib/irb/ext/use-loader.rb
+++ /dev/null
@@ -1,64 +0,0 @@
-#
-#   use-loader.rb -
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-
-require "irb/cmd/load"
-require "irb/ext/loader"
-
-class Object
-  alias __original__load__IRB_use_loader__ load
-  alias __original__require__IRB_use_loader__ require
-end
-
-module IRB
-  module ExtendCommandBundle
-    def irb_load(*opts, &b)
-      ExtendCommand::Load.execute(irb_context, *opts, &b)
-    end
-    def irb_require(*opts, &b)
-      ExtendCommand::Require.execute(irb_context, *opts, &b)
-    end
-  end
-
-  class Context
-
-    IRB.conf[:USE_LOADER] = false
-
-    def use_loader
-      IRB.conf[:USE_LOADER]
-    end
-
-    alias use_loader? use_loader
-
-    def use_loader=(opt)
-
-      if IRB.conf[:USE_LOADER] != opt
-	IRB.conf[:USE_LOADER] = opt
-	if opt
-	  if !$".include?("irb/cmd/load")
-	  end
-	  (class<<@workspace.main;self;end).instance_eval {
-	    alias_method :load, :irb_load
-	    alias_method :require, :irb_require
-	  }
-	else
-	  (class<<@workspace.main;self;end).instance_eval {
-	    alias_method :load, :__original__load__IRB_use_loader__
-	    alias_method :require, :__original__require__IRB_use_loader__
-	  }
-	end
-      end
-      print "Switch to load/require#{unless use_loader; ' non';end} trace mode.\n" if verbose?
-      opt
-    end
-  end
-end
-
-
diff --git a/lib/irb/ext/workspaces.rb b/lib/irb/ext/workspaces.rb
deleted file mode 100644
index 118ea598c0..0000000000
--- a/lib/irb/ext/workspaces.rb
+++ /dev/null
@@ -1,55 +0,0 @@
-#
-#   push-ws.rb -
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-
-module IRB
-  class Context
-
-    def irb_level
-      workspace_stack.size
-    end
-
-    def workspaces
-      if defined? @workspaces
-	@workspaces
-      else
-	@workspaces = []
-      end
-    end
-
-    def push_workspace(*_main)
-      if _main.empty?
-	if workspaces.empty?
-	  print "No other workspace\n"
-	  return nil
-	end
-	ws = workspaces.pop
-	workspaces.push @workspace
-	@workspace = ws
-	return workspaces
-      end
-
-      workspaces.push @workspace
-      @workspace = WorkSpace.new(@workspace.binding, _main[0])
-      if !(class<<main;ancestors;end).include?(ExtendCommandBundle)
-	main.extend ExtendCommandBundle
-      end
-    end
-
-    def pop_workspace
-      if workspaces.empty?
-	print "workspace stack empty\n"
-	return
-      end
-      @workspace = workspaces.pop
-    end
-  end
-end
-
diff --git a/lib/irb/extend-command.rb b/lib/irb/extend-command.rb
deleted file mode 100644
index 190c49ae78..0000000000
--- a/lib/irb/extend-command.rb
+++ /dev/null
@@ -1,268 +0,0 @@
-#
-#   irb/extend-command.rb - irb extend command
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-module IRB
-  #
-  # IRB extended command
-  #
-  module ExtendCommandBundle
-    EXCB = ExtendCommandBundle
-
-    NO_OVERRIDE = 0
-    OVERRIDE_PRIVATE_ONLY = 0x01
-    OVERRIDE_ALL = 0x02
-
-    def irb_exit(ret = 0)
-      irb_context.exit(ret)
-    end
-
-    def irb_context
-      IRB.CurrentContext
-    end
-
-    @ALIASES = [
-      [:context, :irb_context, NO_OVERRIDE],
-      [:conf, :irb_context, NO_OVERRIDE],
-      [:irb_quit, :irb_exit, OVERRIDE_PRIVATE_ONLY],
-      [:exit, :irb_exit, OVERRIDE_PRIVATE_ONLY],
-      [:quit, :irb_exit, OVERRIDE_PRIVATE_ONLY],
-    ]
-
-    @EXTEND_COMMANDS = [
-      [:irb_current_working_workspace, :CurrentWorkingWorkspace, "irb/cmd/chws",
-	[:irb_print_working_workspace, OVERRIDE_ALL],
-	[:irb_cwws, OVERRIDE_ALL],
-	[:irb_pwws, OVERRIDE_ALL],
-#	[:irb_cww, OVERRIDE_ALL],
-#	[:irb_pww, OVERRIDE_ALL],
-	[:cwws, NO_OVERRIDE],
-	[:pwws, NO_OVERRIDE],
-#	[:cww, NO_OVERRIDE],
-#	[:pww, NO_OVERRIDE],
-	[:irb_current_working_binding, OVERRIDE_ALL],
-	[:irb_print_working_binding, OVERRIDE_ALL],
-	[:irb_cwb, OVERRIDE_ALL],
-	[:irb_pwb, OVERRIDE_ALL],
-#	[:cwb, NO_OVERRIDE],
-#	[:pwb, NO_OVERRIDE]
-      ],
-      [:irb_change_workspace, :ChangeWorkspace, "irb/cmd/chws",
-	[:irb_chws, OVERRIDE_ALL],
-#	[:irb_chw, OVERRIDE_ALL],
-	[:irb_cws, OVERRIDE_ALL],
-#	[:irb_cw, OVERRIDE_ALL],
-	[:chws, NO_OVERRIDE],
-#	[:chw, NO_OVERRIDE],
-	[:cws, NO_OVERRIDE],
-#	[:cw, NO_OVERRIDE],
-	[:irb_change_binding, OVERRIDE_ALL],
-	[:irb_cb, OVERRIDE_ALL],
-	[:cb, NO_OVERRIDE]],
-
-      [:irb_workspaces, :Workspaces, "irb/cmd/pushws",
-	[:workspaces, NO_OVERRIDE],
-	[:irb_bindings, OVERRIDE_ALL],
-	[:bindings, NO_OVERRIDE]],
-      [:irb_push_workspace, :PushWorkspace, "irb/cmd/pushws",
-	[:irb_pushws, OVERRIDE_ALL],
-#	[:irb_pushw, OVERRIDE_ALL],
-	[:pushws, NO_OVERRIDE],
-#	[:pushw, NO_OVERRIDE],
-	[:irb_push_binding, OVERRIDE_ALL],
-	[:irb_pushb, OVERRIDE_ALL],
-	[:pushb, NO_OVERRIDE]],
-      [:irb_pop_workspace, :PopWorkspace, "irb/cmd/pushws",
-	[:irb_popws, OVERRIDE_ALL],
-#	[:irb_popw, OVERRIDE_ALL],
-	[:popws, NO_OVERRIDE],
-#	[:popw, NO_OVERRIDE],
-	[:irb_pop_binding, OVERRIDE_ALL],
-	[:irb_popb, OVERRIDE_ALL],
-	[:popb, NO_OVERRIDE]],
-
-      [:irb_load, :Load, "irb/cmd/load"],
-      [:irb_require, :Require, "irb/cmd/load"],
-      [:irb_source, :Source, "irb/cmd/load",
-	[:source, NO_OVERRIDE]],
-
-      [:irb, :IrbCommand, "irb/cmd/subirb"],
-      [:irb_jobs, :Jobs, "irb/cmd/subirb",
-	[:jobs, NO_OVERRIDE]],
-      [:irb_fg, :Foreground, "irb/cmd/subirb",
-	[:fg, NO_OVERRIDE]],
-      [:irb_kill, :Kill, "irb/cmd/subirb",
-	[:kill, OVERRIDE_PRIVATE_ONLY]],
-
-      [:irb_help, :Help, "irb/cmd/help",
-        [:help, NO_OVERRIDE]],
-
-    ]
-
-    def self.install_extend_commands
-      for args in @EXTEND_COMMANDS
-	def_extend_command(*args)
-      end
-    end
-
-    # aliases = [commands_alias, flag], ...
-    def self.def_extend_command(cmd_name, cmd_class, load_file = nil, *aliases)
-      case cmd_class
-      when Symbol
-	cmd_class = cmd_class.id2name
-      when String
-      when Class
-	cmd_class = cmd_class.name
-      end
-
-      if load_file
-	line = __LINE__; eval %[
-	  def #{cmd_name}(*opts, &b)
-	    require "#{load_file}"
-	    arity = ExtendCommand::#{cmd_class}.instance_method(:execute).arity
-	    args = (1..(arity < 0 ? ~arity : arity)).map {|i| "arg" + i.to_s }
-	    args << "*opts" if arity < 0
-	    args << "&block"
-	    args = args.join(", ")
-	    line = __LINE__; eval %[
-	      def #{cmd_name}(\#{args})
-		ExtendCommand::#{cmd_class}.execute(irb_context, \#{args})
-	      end
-	    ], nil, __FILE__, line
-	    send :#{cmd_name}, *opts, &b
-	  end
-	], nil, __FILE__, line
-      else
-	line = __LINE__; eval %[
-	  def #{cmd_name}(*opts, &b)
-	    ExtendCommand::#{cmd_class}.execute(irb_context, *opts, &b)
-	  end
-	], nil, __FILE__, line
-      end
-
-      for ali, flag in aliases
-	@ALIASES.push [ali, cmd_name, flag]
-      end
-    end
-
-    # override = {NO_OVERRIDE, OVERRIDE_PRIVATE_ONLY, OVERRIDE_ALL}
-    def install_alias_method(to, from, override = NO_OVERRIDE)
-      to = to.id2name unless to.kind_of?(String)
-      from = from.id2name unless from.kind_of?(String)
-
-      if override == OVERRIDE_ALL or
-	  (override == OVERRIDE_PRIVATE_ONLY) && !respond_to?(to) or
-	  (override == NO_OVERRIDE) &&  !respond_to?(to, true)
-	target = self
-	(class << self; self; end).instance_eval{
-	  if target.respond_to?(to, true) &&
-	      !target.respond_to?(EXCB.irb_original_method_name(to), true)
-	    alias_method(EXCB.irb_original_method_name(to), to)
-	  end
-	  alias_method to, from
-	}
-      else
-	print "irb: warn: can't alias #{to} from #{from}.\n"
-      end
-    end
-
-    def self.irb_original_method_name(method_name)
-      "irb_" + method_name + "_org"
-    end
-
-    def self.extend_object(obj)
-      unless (class << obj; ancestors; end).include?(EXCB)
-	super
-	for ali, com, flg in @ALIASES
-	  obj.install_alias_method(ali, com, flg)
-	end
-      end
-    end
-
-    install_extend_commands
-  end
-
-  # extension support for Context
-  module ContextExtender
-    CE = ContextExtender
-
-    @EXTEND_COMMANDS = [
-      [:eval_history=, "irb/ext/history.rb"],
-      [:use_tracer=, "irb/ext/tracer.rb"],
-      [:math_mode=, "irb/ext/math-mode.rb"],
-      [:use_loader=, "irb/ext/use-loader.rb"],
-      [:save_history=, "irb/ext/save-history.rb"],
-    ]
-
-    def self.install_extend_commands
-      for args in @EXTEND_COMMANDS
-	def_extend_command(*args)
-      end
-    end
-
-    def self.def_extend_command(cmd_name, load_file, *aliases)
-      line = __LINE__; Context.module_eval %[
-        def #{cmd_name}(*opts, &b)
-	  Context.module_eval {remove_method(:#{cmd_name})}
-	  require "#{load_file}"
-	  send :#{cmd_name}, *opts, &b
-	end
-	for ali in aliases
-	  alias_method ali, cmd_name
-	end
-      ], __FILE__, line
-    end
-
-    CE.install_extend_commands
-  end
-
-  module MethodExtender
-    def def_pre_proc(base_method, extend_method)
-      base_method = base_method.to_s
-      extend_method = extend_method.to_s
-
-      alias_name = new_alias_name(base_method)
-      module_eval %[
-        alias_method alias_name, base_method
-        def #{base_method}(*opts)
-	  send :#{extend_method}, *opts
-	  send :#{alias_name}, *opts
-	end
-      ]
-    end
-
-    def def_post_proc(base_method, extend_method)
-      base_method = base_method.to_s
-      extend_method = extend_method.to_s
-
-      alias_name = new_alias_name(base_method)
-      module_eval %[
-        alias_method alias_name, base_method
-        def #{base_method}(*opts)
-	  send :#{alias_name}, *opts
-	  send :#{extend_method}, *opts
-	end
-      ]
-    end
-
-    # return #{prefix}#{name}#{postfix}<num>
-    def new_alias_name(name, prefix = "__alias_of__", postfix = "__")
-      base_name = "#{prefix}#{name}#{postfix}"
-      all_methods = instance_methods(true) + private_instance_methods(true)
-      same_methods = all_methods.grep(/^#{Regexp.quote(base_name)}[0-9]*$/)
-      return base_name if same_methods.empty?
-      no = same_methods.size
-      while !same_methods.include?(alias_name = base_name + no)
-	no += 1
-      end
-      alias_name
-    end
-  end
-end
-
diff --git a/lib/irb/frame.rb b/lib/irb/frame.rb
deleted file mode 100644
index 8814b47a9d..0000000000
--- a/lib/irb/frame.rb
+++ /dev/null
@@ -1,66 +0,0 @@
-#
-#   frame.rb -
-#   	$Release Version: 0.9$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(Nihon Rational Software Co.,Ltd)
-#
-# --
-#
-#
-#
-
-require "e2mmap"
-
-module IRB
-  class Frame
-    extend Exception2MessageMapper
-    def_exception :FrameOverflow, "frame overflow"
-    def_exception :FrameUnderflow, "frame underflow"
-
-    INIT_STACK_TIMES = 3
-    CALL_STACK_OFFSET = 3
-
-    def initialize
-      @frames = [TOPLEVEL_BINDING] * INIT_STACK_TIMES
-    end
-
-    def trace_func(event, file, line, id, binding)
-      case event
-      when 'call', 'class'
-	@frames.push binding
-      when 'return', 'end'
-	@frames.pop
-      end
-    end
-
-    def top(n = 0)
-      bind = @frames[-(n + CALL_STACK_OFFSET)]
-      Fail FrameUnderflow unless bind
-      bind
-    end
-
-    def bottom(n = 0)
-      bind = @frames[n]
-      Fail FrameOverflow unless bind
-      bind
-    end
-
-    # singleton functions
-    def Frame.bottom(n = 0)
-      @backtrace.bottom(n)
-    end
-
-    def Frame.top(n = 0)
-      @backtrace.top(n)
-    end
-
-    def Frame.sender
-      eval "self", @backtrace.top
-    end
-
-    @backtrace = Frame.new
-    set_trace_func proc{|event, file, line, id, binding, klass|
-      @backtrace.trace_func(event, file, line, id, binding)
-    }
-  end
-end
diff --git a/lib/irb/help.rb b/lib/irb/help.rb
deleted file mode 100644
index 4a308b6e46..0000000000
--- a/lib/irb/help.rb
+++ /dev/null
@@ -1,35 +0,0 @@
-#
-#   irb/help.rb - print usage module
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ishitsuka.com)
-#
-# --
-#
-#
-#
-
-require 'irb/magic-file'
-
-module IRB
-  def IRB.print_usage
-    lc = IRB.conf[:LC_MESSAGES]
-    path = lc.find("irb/help-message")
-    space_line = false
-    IRB::MagicFile.open(path){|f|
-      f.each_line do |l|
-	if /^\s*$/ =~ l
-	  lc.puts l unless space_line
-	  space_line = true
-	  next
-	end
-	space_line = false
-
-	l.sub!(/#.*$/, "")
-	  next if /^\s*$/ =~ l
-	lc.puts l
-      end
-    }
-  end
-end
-
diff --git a/lib/irb/init.rb b/lib/irb/init.rb
deleted file mode 100644
index fce2df4f09..0000000000
--- a/lib/irb/init.rb
+++ /dev/null
@@ -1,305 +0,0 @@
-#
-#   irb/init.rb - irb initialize module
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-
-module IRB
-
-  # initialize config
-  def IRB.setup(ap_path)
-    IRB.init_config(ap_path)
-    IRB.init_error
-    IRB.parse_opts
-    IRB.run_config
-    IRB.load_modules
-
-    unless @CONF[:PROMPT][@CONF[:PROMPT_MODE]]
-      IRB.fail(UndefinedPromptMode, @CONF[:PROMPT_MODE])
-    end
-  end
-
-  # @CONF default setting
-  def IRB.init_config(ap_path)
-    # class instance variables
-    @TRACER_INITIALIZED = false
-
-    # default configurations
-    unless ap_path and @CONF[:AP_NAME]
-      ap_path = File.join(File.dirname(File.dirname(__FILE__)), "irb.rb")
-    end
-    @CONF[:AP_NAME] = File::basename(ap_path, ".rb")
-
-    @CONF[:IRB_NAME] = "irb"
-    @CONF[:IRB_LIB_PATH] = File.dirname(__FILE__)
-
-    @CONF[:RC] = true
-    @CONF[:LOAD_MODULES] = []
-    @CONF[:IRB_RC] = nil
-
-    @CONF[:MATH_MODE] = false
-    @CONF[:USE_READLINE] = false unless defined?(ReadlineInputMethod)
-    @CONF[:INSPECT_MODE] = true
-    @CONF[:USE_TRACER] = false
-    @CONF[:USE_LOADER] = false
-    @CONF[:IGNORE_SIGINT] = true
-    @CONF[:IGNORE_EOF] = false
-    @CONF[:ECHO] = nil
-    @CONF[:VERBOSE] = nil
-
-    @CONF[:EVAL_HISTORY] = nil
-    @CONF[:SAVE_HISTORY] = nil
-
-    @CONF[:BACK_TRACE_LIMIT] = 16
-
-    @CONF[:PROMPT] = {
-      :NULL => {
-	:PROMPT_I => nil,
-	:PROMPT_N => nil,
-	:PROMPT_S => nil,
-	:PROMPT_C => nil,
-	:RETURN => "%s\n"
-      },
-      :DEFAULT => {
-	:PROMPT_I => "%N(%m):%03n:%i> ",
-	:PROMPT_N => "%N(%m):%03n:%i> ",
-	:PROMPT_S => "%N(%m):%03n:%i%l ",
-	:PROMPT_C => "%N(%m):%03n:%i* ",
-	:RETURN => "=> %s\n"
-      },
-      :CLASSIC => {
-	:PROMPT_I => "%N(%m):%03n:%i> ",
-	:PROMPT_N => "%N(%m):%03n:%i> ",
-	:PROMPT_S => "%N(%m):%03n:%i%l ",
-	:PROMPT_C => "%N(%m):%03n:%i* ",
-	:RETURN => "%s\n"
-      },
-      :SIMPLE => {
-	:PROMPT_I => ">> ",
-	:PROMPT_N => ">> ",
-	:PROMPT_S => nil,
-	:PROMPT_C => "?> ",
-	:RETURN => "=> %s\n"
-      },
-      :INF_RUBY => {
-	:PROMPT_I => "%N(%m):%03n:%i> ",
-#	:PROMPT_N => "%N(%m):%03n:%i> ",
-	:PROMPT_N => nil,
-	:PROMPT_S => nil,
-	:PROMPT_C => nil,
-	:RETURN => "%s\n",
-	:AUTO_INDENT => true
-      },
-      :XMP => {
-	:PROMPT_I => nil,
-	:PROMPT_N => nil,
-	:PROMPT_S => nil,
-	:PROMPT_C => nil,
-	:RETURN => "    ==>%s\n"
-      }
-    }
-
-    @CONF[:PROMPT_MODE] = (STDIN.tty? ? :DEFAULT : :NULL)
-    @CONF[:AUTO_INDENT] = false
-
-    @CONF[:CONTEXT_MODE] = 3 # use binding in function on TOPLEVEL_BINDING
-    @CONF[:SINGLE_IRB] = false
-
-#    @CONF[:LC_MESSAGES] = "en"
-    @CONF[:LC_MESSAGES] = Locale.new
-
-    @CONF[:AT_EXIT] = []
-
-    @CONF[:DEBUG_LEVEL] = 1
-  end
-
-  def IRB.init_error
-    @CONF[:LC_MESSAGES].load("irb/error.rb")
-  end
-
-  FEATURE_IOPT_CHANGE_VERSION = "1.9.0"
-
-  # option analyzing
-  def IRB.parse_opts
-    load_path = []
-    while opt = ARGV.shift
-      case opt
-      when "-f"
-	@CONF[:RC] = false
-      when "-m"
-	@CONF[:MATH_MODE] = true
-      when "-d"
-	$DEBUG = true
-	$VERBOSE = true
-      when "-w"
-	$VERBOSE = true
-      when /^-W(.+)?/
-	opt = $1 || ARGV.shift
-	case opt
-	when "0"
-	  $VERBOSE = nil
-	when "1"
-	  $VERBOSE = false
-	else
-	  $VERBOSE = true
-	end
-      when /^-r(.+)?/
-	opt = $1 || ARGV.shift
-	@CONF[:LOAD_MODULES].push opt if opt
-      when /^-I(.+)?/
-        opt = $1 || ARGV.shift
-	load_path.concat(opt.split(File::PATH_SEPARATOR)) if opt
-      when '-U'
-	set_encoding("UTF-8", "UTF-8")
-      when /^-E(.+)?/, /^--encoding(?:=(.+))?/
-	opt = $1 || ARGV.shift
-	set_encoding(*opt.split(':', 2))
-      when "--inspect"
-	if /^-/ !~ ARGV.first
-	  @CONF[:INSPECT_MODE] = ARGV.shift
-	else
-	  @CONF[:INSPECT_MODE] = true
-	end
-      when "--noinspect"
-	@CONF[:INSPECT_MODE] = false
-      when "--readline"
-	@CONF[:USE_READLINE] = true
-      when "--noreadline"
-	@CONF[:USE_READLINE] = false
-      when "--echo"
-	@CONF[:ECHO] = true
-      when "--noecho"
-	@CONF[:ECHO] = false
-      when "--verbose"
-	@CONF[:VERBOSE] = true
-      when "--noverbose"
-	@CONF[:VERBOSE] = false
-      when /^--prompt-mode(?:=(.+))?/, /^--prompt(?:=(.+))?/
-	opt = $1 || ARGV.shift
-	prompt_mode = opt.upcase.tr("-", "_").intern
-	@CONF[:PROMPT_MODE] = prompt_mode
-      when "--noprompt"
-	@CONF[:PROMPT_MODE] = :NULL
-      when "--inf-ruby-mode"
-	@CONF[:PROMPT_MODE] = :INF_RUBY
-      when "--sample-book-mode", "--simple-prompt"
-	@CONF[:PROMPT_MODE] = :SIMPLE
-      when "--tracer"
-	@CONF[:USE_TRACER] = true
-      when /^--back-trace-limit(?:=(.+))?/
-	@CONF[:BACK_TRACE_LIMIT] = ($1 || ARGV.shift).to_i
-      when /^--context-mode(?:=(.+))?/
-	@CONF[:CONTEXT_MODE] = ($1 || ARGV.shift).to_i
-      when "--single-irb"
-	@CONF[:SINGLE_IRB] = true
-      when /^--irb_debug=(?:=(.+))?/
-	@CONF[:DEBUG_LEVEL] = ($1 || ARGV.shift).to_i
-      when "-v", "--version"
-	print IRB.version, "\n"
-	exit 0
-      when "-h", "--help"
-	require "irb/help"
-	IRB.print_usage
-	exit 0
-      when "--"
-	if opt = ARGV.shift
-	  @CONF[:SCRIPT] = opt
-	  $0 = opt
-	end
-        break
-      when /^-/
-	IRB.fail UnrecognizedSwitch, opt
-      else
-	@CONF[:SCRIPT] = opt
-	$0 = opt
-	break
-      end
-    end
-    if RUBY_VERSION >= FEATURE_IOPT_CHANGE_VERSION
-      load_path.collect! do |path|
-	/\A\.\// =~ path ? path : File.expand_path(path)
-      end
-    end
-    $LOAD_PATH.unshift(*load_path)
-
-  end
-
-  # running config
-  def IRB.run_config
-    if @CONF[:RC]
-      begin
-	load rc_file
-      rescue LoadError, Errno::ENOENT
-      rescue # StandardError, ScriptError
-	print "load error: #{rc_file}\n"
-	print $!.class, ": ", $!, "\n"
-	for err in $@[0, $@.size - 2]
-	  print "\t", err, "\n"
-	end
-      end
-    end
-  end
-
-  IRBRC_EXT = "rc"
-  def IRB.rc_file(ext = IRBRC_EXT)
-    if !@CONF[:RC_NAME_GENERATOR]
-      rc_file_generators do |rcgen|
-	@CONF[:RC_NAME_GENERATOR] ||= rcgen
-	if File.exist?(rcgen.call(IRBRC_EXT))
-	  @CONF[:RC_NAME_GENERATOR] = rcgen
-	  break
-	end
-      end
-    end
-    @CONF[:RC_NAME_GENERATOR].call ext
-  end
-
-  # enumerate possible rc-file base name generators
-  def IRB.rc_file_generators
-    if irbrc = ENV["IRBRC"]
-      yield proc{|rc| rc == "rc" ? irbrc : irbrc+rc}
-    end
-    if home = ENV["HOME"]
-      yield proc{|rc| home+"/.irb#{rc}"}
-    end
-    home = Dir.pwd
-    yield proc{|rc| home+"/.irb#{rc}"}
-    yield proc{|rc| home+"/irb#{rc.sub(/\A_?/, '.')}"}
-    yield proc{|rc| home+"/_irb#{rc}"}
-    yield proc{|rc| home+"/$irb#{rc}"}
-  end
-
-  # loading modules
-  def IRB.load_modules
-    for m in @CONF[:LOAD_MODULES]
-      begin
-	require m
-      rescue LoadError => err
-	warn err.backtrace[0] << ":#{err.class}: #{err}"
-      end
-    end
-  end
-
-
-  DefaultEncodings = Struct.new(:external, :internal)
-  class << IRB
-    private
-    def set_encoding(extern, intern = nil)
-      verbose, $VERBOSE = $VERBOSE, nil
-      Encoding.default_external = extern unless extern.nil? || extern.empty?
-      Encoding.default_internal = intern unless intern.nil? || intern.empty?
-      @CONF[:ENCODINGS] = IRB::DefaultEncodings.new(extern, intern)
-      [$stdin, $stdout, $stderr].each do |io|
-	io.set_encoding(extern, intern)
-      end
-      @CONF[:LC_MESSAGES].instance_variable_set(:@encoding, extern)
-    ensure
-      $VERBOSE = verbose
-    end
-  end
-end
diff --git a/lib/irb/input-method.rb b/lib/irb/input-method.rb
deleted file mode 100644
index 7227df4ca0..0000000000
--- a/lib/irb/input-method.rb
+++ /dev/null
@@ -1,142 +0,0 @@
-#
-#   irb/input-method.rb - input methods used irb
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-require 'irb/src_encoding'
-require 'irb/magic-file'
-
-module IRB
-  #
-  # InputMethod
-  #	StdioInputMethod
-  #	FileInputMethod
-  #	(ReadlineInputMethod)
-  #
-  STDIN_FILE_NAME = "(line)"
-  class InputMethod
-    @RCS_ID='-$Id$-'
-
-    def initialize(file = STDIN_FILE_NAME)
-      @file_name = file
-    end
-    attr_reader :file_name
-
-    attr_accessor :prompt
-
-    def gets
-      IRB.fail NotImplementedError, "gets"
-    end
-    public :gets
-
-    def readable_atfer_eof?
-      false
-    end
-  end
-
-  class StdioInputMethod < InputMethod
-    def initialize
-      super
-      @line_no = 0
-      @line = []
-      @stdin = IO.open(STDIN.to_i, :external_encoding => IRB.conf[:LC_MESSAGES].encoding, :internal_encoding => "-")
-      @stdout = IO.open(STDOUT.to_i, 'w', :external_encoding => IRB.conf[:LC_MESSAGES].encoding, :internal_encoding => "-")
-    end
-
-    def gets
-      print @prompt
-      line = @stdin.gets
-      @line[@line_no += 1] = line
-    end
-
-    def eof?
-      @stdin.eof?
-    end
-
-    def readable_atfer_eof?
-      true
-    end
-
-    def line(line_no)
-      @line[line_no]
-    end
-
-    def encoding
-      @stdin.external_encoding
-    end
-  end
-
-  class FileInputMethod < InputMethod
-    def initialize(file)
-      super
-      @io = IRB::MagicFile.open(file)
-    end
-    attr_reader :file_name
-
-    def eof?
-      @io.eof?
-    end
-
-    def gets
-      print @prompt
-      l = @io.gets
-#      print @prompt, l
-      l
-    end
-
-    def encoding
-      @io.external_encoding
-    end
-  end
-
-  begin
-    require "readline"
-    class ReadlineInputMethod < InputMethod
-      include Readline
-      def initialize
-	super
-
-	@line_no = 0
-	@line = []
-	@eof = false
-
-	@stdin = IO.open(STDIN.to_i, :external_encoding => IRB.conf[:LC_MESSAGES].encoding, :internal_encoding => "-")
-	@stdout = IO.open(STDOUT.to_i, 'w', :external_encoding => IRB.conf[:LC_MESSAGES].encoding, :internal_encoding => "-")
-      end
-
-      def gets
-        Readline.input = @stdin
-        Readline.output = @stdout
-	if l = readline(@prompt, false)
-	  HISTORY.push(l) if !l.empty?
-	  @line[@line_no += 1] = l + "\n"
-	else
-	  @eof = true
-	  l
-	end
-      end
-
-      def eof?
-	@eof
-      end
-
-      def readable_atfer_eof?
-	true
-      end
-
-      def line(line_no)
-	@line[line_no]
-      end
-
-      def encoding
-	@stdin.external_encoding
-      end
-    end
-  rescue LoadError
-  end
-end
diff --git a/lib/irb/inspector.rb b/lib/irb/inspector.rb
deleted file mode 100644
index aefe077f37..0000000000
--- a/lib/irb/inspector.rb
+++ /dev/null
@@ -1,109 +0,0 @@
-#
-#   irb/inspector.rb - inspect methods
-#   	$Release Version: 0.9.6$
-#   	$Revision: 1.19 $
-#   	$Date: 2002/06/11 07:51:31 $
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-
-module IRB
-
-  def IRB::Inspector(inspect, init = nil)
-    Inspector.new(inspect, init)
-  end
-
-  class Inspector
-    def initialize(inspect_proc, init_proc = nil)
-      @init = init_proc
-      @inspect = inspect_proc
-    end
-
-    def init
-      @init.call if @init
-    end
-
-    def inspect_value(v)
-      @inspect.call(v)
-    end
-  end
-
-  INSPECTORS = {}
-
-  def INSPECTORS.keys_with_inspector(inspector)
-    select{|k,v| v == inspector}.collect{|k, v| k}
-  end
-
-  # ex)
-  # INSPECTORS.def_inspector(key, init_p=nil){|v| v.inspect}
-  # INSPECTORS.def_inspector([key1,..], init_p=nil){|v| v.inspect}
-  # INSPECTORS.def_inspector(key, inspector)
-  # INSPECTORS.def_inspector([key1,...], inspector)
-
-  def INSPECTORS.def_inspector(key, arg=nil, &block)
-#     if !block_given?
-#       case arg
-#       when nil, Proc
-# 	inspector = IRB::Inspector(init_p)
-#       when Inspector
-# 	inspector = init_p
-#       else
-# 	IRB.Raise IllegalParameter, init_p
-#       end
-#       init_p = nil
-#     else
-#       inspector = IRB::Inspector(block, init_p)
-#     end
-
-    if block_given?
-      inspector = IRB::Inspector(block, arg)
-    else
-      inspector = arg
-    end
-
-    case key
-    when Array
-      for k in key
-	def_inspector(k, inspector)
-      end
-    when Symbol
-      self[key] = inspector
-      self[key.to_s] = inspector
-    when String
-      self[key] = inspector
-      self[key.intern] = inspector
-    else
-      self[key] = inspector
-    end
-  end
-
-  INSPECTORS.def_inspector([false, :to_s, :raw]){|v| v.to_s}
-  INSPECTORS.def_inspector([true, :p, :inspect]){|v|
-    begin
-      v.inspect
-    rescue NoMethodError
-      puts "(Object doesn't support #inspect)"
-    end
-  }
-  INSPECTORS.def_inspector([:pp, :pretty_inspect], proc{require "pp"}){|v| v.pretty_inspect.chomp}
-  INSPECTORS.def_inspector([:yaml, :YAML], proc{require "yaml"}){|v|
-    begin
-      YAML.dump(v)
-    rescue
-      puts "(can't dump yaml. use inspect)"
-      v.inspect
-    end
-  }
-
-  INSPECTORS.def_inspector([:marshal, :Marshal, :MARSHAL, Marshal]){|v|
-    Marshal.dump(v)
-  }
-end
-
-
-
-
-
diff --git a/lib/irb/lc/error.rb b/lib/irb/lc/error.rb
deleted file mode 100644
index 742821e3af..0000000000
--- a/lib/irb/lc/error.rb
+++ /dev/null
@@ -1,29 +0,0 @@
-#
-#   irb/lc/error.rb -
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-require "e2mmap"
-
-module IRB
-
-  # exceptions
-  extend Exception2MessageMapper
-  def_exception :UnrecognizedSwitch, "Unrecognized switch: %s"
-  def_exception :NotImplementedError, "Need to define `%s'"
-  def_exception :CantReturnToNormalMode, "Can't return to normal mode."
-  def_exception :IllegalParameter, "Invalid parameter(%s)."
-  def_exception :IrbAlreadyDead, "Irb is already dead."
-  def_exception :IrbSwitchedToCurrentThread, "Switched to current thread."
-  def_exception :NoSuchJob, "No such job(%s)."
-  def_exception :CantShiftToMultiIrbMode, "Can't shift to multi irb mode."
-  def_exception :CantChangeBinding, "Can't change binding to (%s)."
-  def_exception :UndefinedPromptMode, "Undefined prompt mode(%s)."
-
-end
-
diff --git a/lib/irb/lc/help-message b/lib/irb/lc/help-message
deleted file mode 100644
index c01cdaab93..0000000000
--- a/lib/irb/lc/help-message
+++ /dev/null
@@ -1,40 +0,0 @@
-# -*- coding: US-ASCII -*-
-#
-#   irb/lc/help-message.rb -
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-Usage:  irb.rb [options] [programfile] [arguments]
-  -f		    Suppress read of ~/.irbrc
-  -m		    Bc mode (load mathn, fraction or matrix are available)
-  -d                Set $DEBUG to true (same as `ruby -d')
-  -r load-module    Same as `ruby -r'
-  -I path           Specify $LOAD_PATH directory
-  -U                Same as `ruby -U`
-  -E enc            Same as `ruby -E`
-  -w                Same as `ruby -w`
-  -W[level=2]       Same as `ruby -W`
-  --inspect	    Use `inspect' for output (default except for bc mode)
-  --noinspect	    Don't use inspect for output
-  --readline	    Use Readline extension module
-  --noreadline	    Don't use Readline extension module
-  --prompt prompt-mode
-  --prompt-mode prompt-mode
-		    Switch prompt mode. Pre-defined prompt modes are
-		    `default', `simple', `xmp' and `inf-ruby'
-  --inf-ruby-mode   Use prompt appropriate for inf-ruby-mode on emacs.
-		    Suppresses --readline.
-  --simple-prompt   Simple prompt mode
-  --noprompt	    No prompt mode
-  --tracer	    Display trace for each execution of commands.
-  --back-trace-limit n
-		    Display backtrace top n and tail n. The default
-		    value is 16.
-  --irb_debug n	    Set internal debug level to n (not for popular use)
-  -v, --version	    Print the version of irb
-# vim:fileencoding=us-ascii
diff --git a/lib/irb/lc/ja/encoding_aliases.rb b/lib/irb/lc/ja/encoding_aliases.rb
deleted file mode 100644
index a713dff4be..0000000000
--- a/lib/irb/lc/ja/encoding_aliases.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-module IRB
-  class Locale
-    @@legacy_encoding_alias_map = {
-      'ujis' => Encoding::EUC_JP,
-      'euc' => Encoding::EUC_JP
-    }.freeze
-  end
-end
diff --git a/lib/irb/lc/ja/error.rb b/lib/irb/lc/ja/error.rb
deleted file mode 100644
index 9a7670f459..0000000000
--- a/lib/irb/lc/ja/error.rb
+++ /dev/null
@@ -1,27 +0,0 @@
-# -*- coding: utf-8 -*-
-#   irb/lc/ja/error.rb -
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-require "e2mmap"
-
-module IRB
-  # exceptions
-  extend Exception2MessageMapper
-  def_exception :UnrecognizedSwitch, 'スイッチ(%s)が分りません'
-  def_exception :NotImplementedError, '`%s\'の定義が必要です'
-  def_exception :CantReturnToNormalMode, 'Normalモードに戻れません.'
-  def_exception :IllegalParameter, 'パラメータ(%s)が間違っています.'
-  def_exception :IrbAlreadyDead, 'Irbは既に死んでいます.'
-  def_exception :IrbSwitchedToCurrentThread, 'カレントスレッドに切り替わりました.'
-  def_exception :NoSuchJob, 'そのようなジョブ(%s)はありません.'
-  def_exception :CantShiftToMultiIrbMode, 'multi-irb modeに移れません.'
-  def_exception :CantChangeBinding, 'バインディング(%s)に変更できません.'
-  def_exception :UndefinedPromptMode, 'プロンプトモード(%s)は定義されていません.'
-end
-# vim:fileencoding=utf-8
diff --git a/lib/irb/lc/ja/help-message b/lib/irb/lc/ja/help-message
deleted file mode 100644
index 57e8f23edf..0000000000
--- a/lib/irb/lc/ja/help-message
+++ /dev/null
@@ -1,41 +0,0 @@
-# -*- coding: utf-8 -*-
-#   irb/lc/ja/help-message.rb -
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-Usage:  irb.rb [options] [programfile] [arguments]
-  -f		    ~/.irbrc を読み込まない.
-  -m		    bcモード(分数, 行列の計算ができる)
-  -d                $DEBUG をtrueにする(ruby -d と同じ)
-  -r load-module    ruby -r と同じ.
-  -I path           $LOAD_PATH に path を追加する.
-  -U                ruby -U と同じ.
-  -E enc            ruby -E と同じ.
-  -w                ruby -w と同じ.
-  -W[level=2]       ruby -W と同じ.
-  --inspect	    結果出力にinspectを用いる(bcモード以外はデフォルト).
-  --noinspect	    結果出力にinspectを用いない.
-  --readline	    readlineライブラリを利用する.
-  --noreadline	    readlineライブラリを利用しない.
-  --prompt prompt-mode/--prompt-mode prompt-mode
-		    プロンプトモードを切替えます. 現在定義されているプ
-		    ロンプトモードは, default, simple, xmp, inf-rubyが
-		    用意されています.
-  --inf-ruby-mode   emacsのinf-ruby-mode用のプロンプト表示を行なう. 特
-		    に指定がない限り, readlineライブラリは使わなくなる.
-  --simple-prompt   非常にシンプルなプロンプトを用いるモードです.
-  --noprompt	    プロンプト表示を行なわない.
-  --tracer	    コマンド実行時にトレースを行なう.
-  --back-trace-limit n
-		    バックトレース表示をバックトレースの頭から n, 後ろ
-		    からnだけ行なう. デフォルトは16
-  --irb_debug n	    irbのデバッグデバッグレベルをnに設定する(利用しな
-		    い方が無難でしょう).
-  -v, --version	    irbのバージョンを表示する
-
-# vim:fileencoding=utf-8
diff --git a/lib/irb/locale.rb b/lib/irb/locale.rb
deleted file mode 100644
index 7781006da4..0000000000
--- a/lib/irb/locale.rb
+++ /dev/null
@@ -1,182 +0,0 @@
-#
-#   irb/locale.rb - internationalization module
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-module IRB
-  class Locale
-    @RCS_ID='-$Id$-'
-
-    LOCALE_NAME_RE = %r[
-      (?<language>[[:alpha:]]{2,3})
-      (?:_  (?<territory>[[:alpha:]]{2,3}) )?
-      (?:\. (?<codeset>[^@]+) )?
-      (?:@  (?<modifier>.*) )?
-    ]x
-    LOCALE_DIR = "/lc/"
-
-    @@legacy_encoding_alias_map = {}.freeze
-
-    def initialize(locale = nil)
-      @lang = @territory = @encoding_name = @modifier = nil
-      @locale = locale || ENV["IRB_LANG"] || ENV["LC_MESSAGES"] || ENV["LC_ALL"] || ENV["LANG"] || "C"
-      if m = LOCALE_NAME_RE.match(@locale)
-	@lang, @territory, @encoding_name, @modifier = m[:language], m[:territory], m[:codeset], m[:modifier]
-
-	if @encoding_name
-	  begin load 'irb/encoding_aliases.rb'; rescue LoadError; end
-	  if @encoding = @@legacy_encoding_alias_map[@encoding_name]
-	    warn "%s is obsolete. use %s" % ["#{@lang}_#{@territory}.#{@encoding_name}", "#{@lang}_#{@territory}.#{@encoding.name}"]
-	  end
-	  @encoding = Encoding.find(@encoding_name) rescue nil
-	end
-      end
-      @encoding ||= (Encoding.find('locale') rescue Encoding::ASCII_8BIT)
-    end
-
-    attr_reader :lang, :territory, :encoding, :modifieer
-
-    def String(mes)
-      mes = super(mes)
-      if @encoding
-	mes.encode(@encoding, undef: :replace)
-      else
-	mes
-      end
-    end
-
-    def format(*opts)
-      String(super(*opts))
-    end
-
-    def gets(*rs)
-      String(super(*rs))
-    end
-
-    def readline(*rs)
-      String(super(*rs))
-    end
-
-    def print(*opts)
-      ary = opts.collect{|opt| String(opt)}
-      super(*ary)
-    end
-
-    def printf(*opts)
-      s = format(*opts)
-      print s
-    end
-
-    def puts(*opts)
-      ary = opts.collect{|opt| String(opt)}
-      super(*ary)
-    end
-
-    def require(file, priv = nil)
-      rex = Regexp.new("lc/#{Regexp.quote(file)}\.(so|o|sl|rb)?")
-      return false if $".find{|f| f =~ rex}
-
-      case file
-      when /\.rb$/
-	begin
-	  load(file, priv)
-	  $".push file
-	  return true
-	rescue LoadError
-	end
-      when /\.(so|o|sl)$/
-	return super
-      end
-
-      begin
-	load(f = file + ".rb")
-	$".push f  #"
-	return true
-      rescue LoadError
-	return ruby_require(file)
-      end
-    end
-
-    alias toplevel_load load
-
-    def load(file, priv=nil)
-      found = find(file)
-      if found
-        return real_load(found, priv)
-      else
-        raise LoadError, "No such file to load -- #{file}"
-      end
-    end
-
-    def find(file , paths = $:)
-      dir = File.dirname(file)
-      dir = "" if dir == "."
-      base = File.basename(file)
-
-      if dir.start_with?('/')
-        return each_localized_path(dir, base).find{|full_path| File.readable? full_path}
-      else
-        return search_file(paths, dir, base)
-      end
-    end
-
-    private
-    def real_load(path, priv)
-      src = MagicFile.open(path){|f| f.read}
-      if priv
-	eval("self", TOPLEVEL_BINDING).extend(Module.new {eval(src, nil, path)})
-      else
-	eval(src, TOPLEVEL_BINDING, path)
-      end
-    end
-
-    # @param paths load paths in which IRB find a localized file.
-    # @param dir directory
-    # @param file basename to be localized
-    #
-    # typically, for the parameters and a <path> in paths, it searches
-    #   <path>/<dir>/<locale>/<file>
-    def search_file(lib_paths, dir, file)
-      each_localized_path(dir, file) do |lc_path|
-        lib_paths.each do |libpath|
-          full_path = File.join(libpath, lc_path)
-          return full_path if File.readable?(full_path)
-        end
-        redo if defined?(Gem) and Gem.try_activate(lc_path)
-      end
-      nil
-    end
-
-    def each_localized_path(dir, file)
-      return enum_for(:each_localized_path) unless block_given?
-      each_sublocale do |lc|
-        yield lc.nil? ? File.join(dir, LOCALE_DIR, file) : File.join(dir, LOCALE_DIR, lc, file)
-      end
-    end
-
-    def each_sublocale
-      if @lang
-	if @territory
-	  if @encoding_name
-	    yield "#{@lang}_#{@territory}.#{@encoding_name}@#{@modifier}" if @modifier
-	    yield "#{@lang}_#{@territory}.#{@encoding_name}"
-	  end
-	  yield "#{@lang}_#{@territory}@#{@modifier}" if @modifier
-	  yield "#{@lang}_#{@territory}"
-	end
-        if @encoding_name
-          yield "#{@lang}.#{@encoding_name}@#{@modifier}" if @modifier
-          yield "#{@lang}.#{@encoding_name}"
-        end
-	yield "#{@lang}@#{@modifier}" if @modifier
-	yield "#{@lang}"
-      end
-      yield nil
-    end
-  end
-end
diff --git a/lib/irb/magic-file.rb b/lib/irb/magic-file.rb
deleted file mode 100644
index 339ed60b6b..0000000000
--- a/lib/irb/magic-file.rb
+++ /dev/null
@@ -1,37 +0,0 @@
-module IRB
-  class << (MagicFile = Object.new)
-    # see parser_magic_comment in parse.y
-    ENCODING_SPEC_RE = %r"coding\s*[=:]\s*([[:alnum:]\-_]+)"
-
-    def open(path)
-      io = File.open(path, 'rb')
-      line = io.gets
-      line = io.gets if line[0,2] == "#!"
-      encoding = detect_encoding(line)
-      internal_encoding = encoding
-      encoding ||= default_src_encoding
-      io.rewind
-      io.set_encoding(encoding, internal_encoding)
-
-      if block_given?
-        begin
-          return (yield io)
-        ensure
-          io.close
-        end
-      else
-        return io
-      end
-    end
-
-    private
-    def detect_encoding(line)
-      return unless line[0] == ?#
-      line = line[1..-1]
-      line = $1 if line[/-\*-\s*(.*?)\s*-*-$/]
-      return nil unless ENCODING_SPEC_RE =~ line
-      encoding = $1
-      return encoding.sub(/-(?:mac|dos|unix)/i, '')
-    end
-  end
-end
diff --git a/lib/irb/notifier.rb b/lib/irb/notifier.rb
deleted file mode 100644
index d20679da4a..0000000000
--- a/lib/irb/notifier.rb
+++ /dev/null
@@ -1,144 +0,0 @@
-#
-#   notifier.rb - output methods used by irb
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-
-require "e2mmap"
-require "irb/output-method"
-
-module IRB
-  module Notifier
-    extend Exception2MessageMapper
-    def_exception :ErrUndefinedNotifier,
-      "undefined notifier level: %d is specified"
-    def_exception :ErrUnrecognizedLevel,
-      "unrecognized notifier level: %s is specified"
-
-    def def_notifier(prefix = "", output_method = StdioOutputMethod.new)
-      CompositeNotifier.new(prefix, output_method)
-    end
-    module_function :def_notifier
-
-    class AbstractNotifier
-      def initialize(prefix, base_notifier)
-	@prefix = prefix
-	@base_notifier = base_notifier
-      end
-
-      attr_reader :prefix
-
-      def notify?
-	true
-      end
-
-      def print(*opts)
-	@base_notifier.print prefix, *opts if notify?
-      end
-
-      def printn(*opts)
-	@base_notifier.printn prefix, *opts if notify?
-      end
-
-      def printf(format, *opts)
-	@base_notifier.printf(prefix + format, *opts) if notify?
-      end
-
-      def puts(*objs)
-	if notify?
-	  @base_notifier.puts(*objs.collect{|obj| prefix + obj.to_s})
-	end
-      end
-
-      def pp(*objs)
-	if notify?
-	  @base_notifier.ppx @prefix, *objs
-	end
-      end
-
-      def ppx(prefix, *objs)
-	if notify?
-	  @base_notifier.ppx @prefix+prefix, *objs
-	end
-      end
-
-      def exec_if
-	yield(@base_notifier) if notify?
-      end
-    end
-
-    class CompositeNotifier<AbstractNotifier
-      def initialize(prefix, base_notifier)
-	super
-
-	@notifiers = [D_NOMSG]
-	@level_notifier = D_NOMSG
-      end
-
-      attr_reader :notifiers
-
-      def def_notifier(level, prefix = "")
-	notifier = LeveledNotifier.new(self, level, prefix)
-	@notifiers[level] = notifier
-	notifier
-      end
-
-      attr_reader :level_notifier
-      alias level level_notifier
-
-      def level_notifier=(value)
-	case value
-	when AbstractNotifier
-	  @level_notifier = value
-	when Integer
-	  l = @notifiers[value]
-	  Notifier.Raise ErrUndefinedNotifer, value unless l
-	  @level_notifier = l
-	else
-	  Notifier.Raise ErrUnrecognizedLevel, value unless l
-	end
-      end
-
-      alias level= level_notifier=
-    end
-
-    class LeveledNotifier<AbstractNotifier
-      include Comparable
-
-      def initialize(base, level, prefix)
-	super(prefix, base)
-
-	@level = level
-      end
-
-      attr_reader :level
-
-      def <=>(other)
-	@level <=> other.level
-      end
-
-      def notify?
-	@base_notifier.level >= self
-      end
-    end
-
-    class NoMsgNotifier<LeveledNotifier
-      def initialize
-	@base_notifier = nil
-	@level = 0
-	@prefix = ""
-      end
-
-      def notify?
-	false
-      end
-    end
-
-    D_NOMSG = NoMsgNotifier.new
-  end
-end
diff --git a/lib/irb/output-method.rb b/lib/irb/output-method.rb
deleted file mode 100644
index 9cccda1c6a..0000000000
--- a/lib/irb/output-method.rb
+++ /dev/null
@@ -1,69 +0,0 @@
-#
-#   output-method.rb - output methods used by irb
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-
-require "e2mmap"
-
-module IRB
-  # OutputMethod
-  #   StdioOutputMethod
-
-  class OutputMethod
-    @RCS_ID='-$Id$-'
-
-    def print(*opts)
-      IRB.fail NotImplementError, "print"
-    end
-
-    def printn(*opts)
-      print opts.join(" "), "\n"
-    end
-
-    # extend printf
-    def printf(format, *opts)
-      if /(%*)%I/ =~ format
-	format, opts = parse_printf_format(format, opts)
-      end
-      print sprintf(format, *opts)
-    end
-
-    # %
-    # <flag>  [#0- +]
-    # <minimum field width> (\*|\*[1-9][0-9]*\$|[1-9][0-9]*)
-    # <precision>.(\*|\*[1-9][0-9]*\$|[1-9][0-9]*|)?
-    # #<length modifier>(hh|h|l|ll|L|q|j|z|t)
-    # <conversion specifier>[diouxXeEfgGcsb%]
-    def parse_printf_format(format, opts)
-      return format, opts if $1.size % 2 == 1
-    end
-
-    def puts(*objs)
-      for obj in objs
-	print(*obj)
-	print "\n"
-      end
-    end
-
-    def pp(*objs)
-      puts(*objs.collect{|obj| obj.inspect})
-    end
-
-    def ppx(prefix, *objs)
-      puts(*objs.collect{|obj| prefix+obj.inspect})
-    end
-
-  end
-
-  class StdioOutputMethod<OutputMethod
-    def print(*opts)
-      STDOUT.print(*opts)
-    end
-  end
-end
diff --git a/lib/irb/ruby-lex.rb b/lib/irb/ruby-lex.rb
deleted file mode 100644
index 2a23534bf3..0000000000
--- a/lib/irb/ruby-lex.rb
+++ /dev/null
@@ -1,1187 +0,0 @@
-#
-#   irb/ruby-lex.rb - ruby lexcal analyzer
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-
-require "e2mmap"
-require "irb/slex"
-require "irb/ruby-token"
-
-class RubyLex
-  @RCS_ID='-$Id$-'
-
-  extend Exception2MessageMapper
-  def_exception(:AlreadyDefinedToken, "Already defined token(%s)")
-  def_exception(:TkReading2TokenNoKey, "key nothing(key='%s')")
-  def_exception(:TkSymbol2TokenNoKey, "key nothing(key='%s')")
-  def_exception(:TkReading2TokenDuplicateError,
-		"key duplicate(token_n='%s', key='%s')")
-  def_exception(:SyntaxError, "%s")
-
-  def_exception(:TerminateLineInput, "Terminate Line Input")
-
-  include RubyToken
-
-  class << self
-    attr_accessor :debug_level
-    def debug?
-      @debug_level > 0
-    end
-  end
-  @debug_level = 0
-
-  def initialize
-    lex_init
-    set_input(STDIN)
-
-    @seek = 0
-    @exp_line_no = @line_no = 1
-    @base_char_no = 0
-    @char_no = 0
-    @rests = []
-    @readed = []
-    @here_readed = []
-
-    @indent = 0
-    @indent_stack = []
-    @lex_state = EXPR_BEG
-    @space_seen = false
-    @here_header = false
-
-    @continue = false
-    @line = ""
-
-    @skip_space = false
-    @readed_auto_clean_up = false
-    @exception_on_syntax_error = true
-
-    @prompt = nil
-  end
-
-  attr_accessor :skip_space
-  attr_accessor :readed_auto_clean_up
-  attr_accessor :exception_on_syntax_error
-
-  attr_reader :seek
-  attr_reader :char_no
-  attr_reader :line_no
-  attr_reader :indent
-
-  # io functions
-  def set_input(io, p = nil, &block)
-    @io = io
-    if p.respond_to?(:call)
-      @input = p
-    elsif block_given?
-      @input = block
-    else
-      @input = Proc.new{@io.gets}
-    end
-  end
-
-  def get_readed
-    if idx = @readed.reverse.index("\n")
-      @base_char_no = idx
-    else
-      @base_char_no += @readed.size
-    end
-
-    readed = @readed.join("")
-    @readed = []
-    readed
-  end
-
-  def getc
-    while @rests.empty?
-#      return nil unless buf_input
-      @rests.push nil unless buf_input
-    end
-    c = @rests.shift
-    if @here_header
-      @here_readed.push c
-    else
-      @readed.push c
-    end
-    @seek += 1
-    if c == "\n"
-      @line_no += 1
-      @char_no = 0
-    else
-      @char_no += 1
-    end
-    c
-  end
-
-  def gets
-    l = ""
-    while c = getc
-      l.concat(c)
-      break if c == "\n"
-    end
-    return nil if l == "" and c.nil?
-    l
-  end
-
-  def eof?
-    @io.eof?
-  end
-
-  def getc_of_rests
-    if @rests.empty?
-      nil
-    else
-      getc
-    end
-  end
-
-  def ungetc(c = nil)
-    if @here_readed.empty?
-      c2 = @readed.pop
-    else
-      c2 = @here_readed.pop
-    end
-    c = c2 unless c
-    @rests.unshift c #c =
-    @seek -= 1
-    if c == "\n"
-      @line_no -= 1
-      if idx = @readed.reverse.index("\n")
-	@char_no = @readed.size - idx
-      else
-	@char_no = @base_char_no + @readed.size
-      end
-    else
-      @char_no -= 1
-    end
-  end
-
-  def peek_equal?(str)
-    chrs = str.split(//)
-    until @rests.size >= chrs.size
-      return false unless buf_input
-    end
-    @rests[0, chrs.size] == chrs
-  end
-
-  def peek_match?(regexp)
-    while @rests.empty?
-      return false unless buf_input
-    end
-    regexp =~ @rests.join("")
-  end
-
-  def peek(i = 0)
-    while @rests.size <= i
-      return nil unless buf_input
-    end
-    @rests[i]
-  end
-
-  def buf_input
-    prompt
-    line = @input.call
-    return nil unless line
-    @rests.concat line.chars.to_a
-    true
-  end
-  private :buf_input
-
-  def set_prompt(p = nil, &block)
-    p = block if block_given?
-    if p.respond_to?(:call)
-      @prompt = p
-    else
-      @prompt = Proc.new{print p}
-    end
-  end
-
-  def prompt
-    if @prompt
-      @prompt.call(@ltype, @indent, @continue, @line_no)
-    end
-  end
-
-  def initialize_input
-    @ltype = nil
-    @quoted = nil
-    @indent = 0
-    @indent_stack = []
-    @lex_state = EXPR_BEG
-    @space_seen = false
-    @here_header = false
-
-    @continue = false
-    prompt
-
-    @line = ""
-    @exp_line_no = @line_no
-  end
-
-  def each_top_level_statement
-    initialize_input
-    catch(:TERM_INPUT) do
-      loop do
-	begin
-	  @continue = false
-	  prompt
-	  unless l = lex
-	    throw :TERM_INPUT if @line == ''
-	  else
-	    @line.concat l
-	    if @ltype or @continue or @indent > 0
-	      next
-	    end
-	  end
-	  if @line != "\n"
-            @line.force_encoding(@io.encoding)
-	    yield @line, @exp_line_no
-	  end
-	  break unless l
-	  @line = ''
-	  @exp_line_no = @line_no
-
-	  @indent = 0
-	  @indent_stack = []
-	  prompt
-	rescue TerminateLineInput
-	  initialize_input
-	  prompt
-	  get_readed
-	end
-      end
-    end
-  end
-
-  def lex
-    until (((tk = token).kind_of?(TkNL) || tk.kind_of?(TkEND_OF_SCRIPT)) &&
-	     !@continue or
-	     tk.nil?)
-      #p tk
-      #p @lex_state
-      #p self
-    end
-    line = get_readed
-    #      print self.inspect
-    if line == "" and tk.kind_of?(TkEND_OF_SCRIPT) || tk.nil?
-      nil
-    else
-      line
-    end
-  end
-
-  def token
-    #      require "tracer"
-    #      Tracer.on
-    @prev_seek = @seek
-    @prev_line_no = @line_no
-    @prev_char_no = @char_no
-    begin
-      begin
-	tk = @OP.match(self)
-	@space_seen = tk.kind_of?(TkSPACE)
-      rescue SyntaxError
-	raise if @exception_on_syntax_error
-	tk = TkError.new(@seek, @line_no, @char_no)
-      end
-    end while @skip_space and tk.kind_of?(TkSPACE)
-    if @readed_auto_clean_up
-      get_readed
-    end
-    #      Tracer.off
-    tk
-  end
-
-  ENINDENT_CLAUSE = [
-    "case", "class", "def", "do", "for", "if",
-    "module", "unless", "until", "while", "begin" #, "when"
-  ]
-  DEINDENT_CLAUSE = ["end" #, "when"
-  ]
-
-  PERCENT_LTYPE = {
-    "q" => "\'",
-    "Q" => "\"",
-    "x" => "\`",
-    "r" => "/",
-    "w" => "]",
-    "W" => "]",
-    "s" => ":"
-  }
-
-  PERCENT_PAREN = {
-    "{" => "}",
-    "[" => "]",
-    "<" => ">",
-    "(" => ")"
-  }
-
-  Ltype2Token = {
-    "\'" => TkSTRING,
-    "\"" => TkSTRING,
-    "\`" => TkXSTRING,
-    "/" => TkREGEXP,
-    "]" => TkDSTRING,
-    ":" => TkSYMBOL
-  }
-  DLtype2Token = {
-    "\"" => TkDSTRING,
-    "\`" => TkDXSTRING,
-    "/" => TkDREGEXP,
-  }
-
-  def lex_init()
-    @OP = IRB::SLex.new
-    @OP.def_rules("\0", "\004", "\032") do |op, io|
-      Token(TkEND_OF_SCRIPT)
-    end
-
-    @OP.def_rules(" ", "\t", "\f", "\r", "\13") do |op, io|
-      @space_seen = true
-      while getc =~ /[ \t\f\r\13]/; end
-      ungetc
-      Token(TkSPACE)
-    end
-
-    @OP.def_rule("#") do |op, io|
-      identify_comment
-    end
-
-    @OP.def_rule("=begin",
-		 proc{|op, io| @prev_char_no == 0 && peek(0) =~ /\s/}) do
-      |op, io|
-      @ltype = "="
-      until getc == "\n"; end
-      until peek_equal?("=end") && peek(4) =~ /\s/
-	until getc == "\n"; end
-      end
-      gets
-      @ltype = nil
-      Token(TkRD_COMMENT)
-    end
-
-    @OP.def_rule("\n") do |op, io|
-      print "\\n\n" if RubyLex.debug?
-      case @lex_state
-      when EXPR_BEG, EXPR_FNAME, EXPR_DOT
-	@continue = true
-      else
-	@continue = false
-	@lex_state = EXPR_BEG
-	until (@indent_stack.empty? ||
-	       [TkLPAREN, TkLBRACK, TkLBRACE,
-		 TkfLPAREN, TkfLBRACK, TkfLBRACE].include?(@indent_stack.last))
-	  @indent_stack.pop
-	end
-      end
-      @here_header = false
-      @here_readed = []
-      Token(TkNL)
-    end
-
-    @OP.def_rules("*", "**",
-		  "=", "==", "===",
-		  "=~", "<=>",
-		  "<", "<=",
-		  ">", ">=", ">>",
-		  "!", "!=", "!~") do
-      |op, io|
-      case @lex_state
-      when EXPR_FNAME, EXPR_DOT
-	@lex_state = EXPR_ARG
-      else
-	@lex_state = EXPR_BEG
-      end
-      Token(op)
-    end
-
-    @OP.def_rules("<<") do
-      |op, io|
-      tk = nil
-      if @lex_state != EXPR_END && @lex_state != EXPR_CLASS &&
-	  (@lex_state != EXPR_ARG || @space_seen)
-	c = peek(0)
-	if /\S/ =~ c && (/["'`]/ =~ c || /\w/ =~ c || c == "-")
-	  tk = identify_here_document
-	end
-      end
-      unless tk
-	tk = Token(op)
-	case @lex_state
-	when EXPR_FNAME, EXPR_DOT
-	  @lex_state = EXPR_ARG
-	else
-	  @lex_state = EXPR_BEG
-	end
-      end
-      tk
-    end
-
-    @OP.def_rules("'", '"') do
-      |op, io|
-      identify_string(op)
-    end
-
-    @OP.def_rules("`") do
-      |op, io|
-      if @lex_state == EXPR_FNAME
-	@lex_state = EXPR_END
-	Token(op)
-      else
-	identify_string(op)
-      end
-    end
-
-    @OP.def_rules('?') do
-      |op, io|
-      if @lex_state == EXPR_END
-	@lex_state = EXPR_BEG
-	Token(TkQUESTION)
-      else
-	ch = getc
-	if @lex_state == EXPR_ARG && ch =~ /\s/
-	  ungetc
-	  @lex_state = EXPR_BEG;
-	  Token(TkQUESTION)
-	else
-	  if (ch == '\\')
-	    read_escape
-	  end
-	  @lex_state = EXPR_END
-	  Token(TkINTEGER)
-	end
-      end
-    end
-
-    @OP.def_rules("&", "&&", "|", "||") do
-      |op, io|
-      @lex_state = EXPR_BEG
-      Token(op)
-    end
-
-    @OP.def_rules("+=", "-=", "*=", "**=",
-		  "&=", "|=", "^=", "<<=", ">>=", "||=", "&&=") do
-      |op, io|
-      @lex_state = EXPR_BEG
-      op =~ /^(.*)=$/
-      Token(TkOPASGN, $1)
-    end
-
-    @OP.def_rule("+@", proc{|op, io| @lex_state == EXPR_FNAME}) do
-      |op, io|
-      @lex_state = EXPR_ARG
-      Token(op)
-    end
-
-    @OP.def_rule("-@", proc{|op, io| @lex_state == EXPR_FNAME}) do
-      |op, io|
-      @lex_state = EXPR_ARG
-      Token(op)
-    end
-
-    @OP.def_rules("+", "-") do
-      |op, io|
-      catch(:RET) do
-	if @lex_state == EXPR_ARG
-	  if @space_seen and peek(0) =~ /[0-9]/
-	    throw :RET, identify_number
-	  else
-	    @lex_state = EXPR_BEG
-	  end
-	elsif @lex_state != EXPR_END and peek(0) =~ /[0-9]/
-	  throw :RET, identify_number
-	else
-	  @lex_state = EXPR_BEG
-	end
-	Token(op)
-      end
-    end
-
-    @OP.def_rule(".") do
-      |op, io|
-      @lex_state = EXPR_BEG
-      if peek(0) =~ /[0-9]/
-	ungetc
-	identify_number
-      else
-	# for "obj.if" etc.
-	@lex_state = EXPR_DOT
-	Token(TkDOT)
-      end
-    end
-
-    @OP.def_rules("..", "...") do
-      |op, io|
-      @lex_state = EXPR_BEG
-      Token(op)
-    end
-
-    lex_int2
-  end
-
-  def lex_int2
-    @OP.def_rules("]", "}", ")") do
-      |op, io|
-      @lex_state = EXPR_END
-      @indent -= 1
-      @indent_stack.pop
-      Token(op)
-    end
-
-    @OP.def_rule(":") do
-      |op, io|
-      if @lex_state == EXPR_END || peek(0) =~ /\s/
-	@lex_state = EXPR_BEG
-	Token(TkCOLON)
-      else
-	@lex_state = EXPR_FNAME;
-	Token(TkSYMBEG)
-      end
-    end
-
-    @OP.def_rule("::") do
-       |op, io|
-#      p @lex_state.id2name, @space_seen
-      if @lex_state == EXPR_BEG or @lex_state == EXPR_ARG && @space_seen
-	@lex_state = EXPR_BEG
-	Token(TkCOLON3)
-      else
-	@lex_state = EXPR_DOT
-	Token(TkCOLON2)
-      end
-    end
-
-    @OP.def_rule("/") do
-      |op, io|
-      if @lex_state == EXPR_BEG || @lex_state == EXPR_MID
-	identify_string(op)
-      elsif peek(0) == '='
-	getc
-	@lex_state = EXPR_BEG
-	Token(TkOPASGN, "/") #/)
-      elsif @lex_state == EXPR_ARG and @space_seen and peek(0) !~ /\s/
-	identify_string(op)
-      else
-	@lex_state = EXPR_BEG
-	Token("/") #/)
-      end
-    end
-
-    @OP.def_rules("^") do
-      |op, io|
-      @lex_state = EXPR_BEG
-      Token("^")
-    end
-
-    #       @OP.def_rules("^=") do
-    # 	@lex_state = EXPR_BEG
-    # 	Token(OP_ASGN, :^)
-    #       end
-
-    @OP.def_rules(",") do
-      |op, io|
-      @lex_state = EXPR_BEG
-      Token(op)
-    end
-
-    @OP.def_rules(";") do
-      |op, io|
-      @lex_state = EXPR_BEG
-      until (@indent_stack.empty? ||
-	     [TkLPAREN, TkLBRACK, TkLBRACE,
-	       TkfLPAREN, TkfLBRACK, TkfLBRACE].include?(@indent_stack.last))
-	@indent_stack.pop
-      end
-      Token(op)
-    end
-
-    @OP.def_rule("~") do
-      |op, io|
-      @lex_state = EXPR_BEG
-      Token("~")
-    end
-
-    @OP.def_rule("~@", proc{|op, io| @lex_state == EXPR_FNAME}) do
-      |op, io|
-      @lex_state = EXPR_BEG
-      Token("~")
-    end
-
-    @OP.def_rule("(") do
-      |op, io|
-      @indent += 1
-      if @lex_state == EXPR_BEG || @lex_state == EXPR_MID
-	@lex_state = EXPR_BEG
-	tk_c = TkfLPAREN
-      else
-	@lex_state = EXPR_BEG
-	tk_c = TkLPAREN
-      end
-      @indent_stack.push tk_c
-      Token(tk_c)
-    end
-
-    @OP.def_rule("[]", proc{|op, io| @lex_state == EXPR_FNAME}) do
-      |op, io|
-      @lex_state = EXPR_ARG
-      Token("[]")
-    end
-
-    @OP.def_rule("[]=", proc{|op, io| @lex_state == EXPR_FNAME}) do
-      |op, io|
-      @lex_state = EXPR_ARG
-      Token("[]=")
-    end
-
-    @OP.def_rule("[") do
-      |op, io|
-      @indent += 1
-      if @lex_state == EXPR_FNAME
-	tk_c = TkfLBRACK
-      else
-	if @lex_state == EXPR_BEG || @lex_state == EXPR_MID
-	  tk_c = TkLBRACK
-	elsif @lex_state == EXPR_ARG && @space_seen
-	  tk_c = TkLBRACK
-	else
-	  tk_c = TkfLBRACK
-	end
-	@lex_state = EXPR_BEG
-      end
-      @indent_stack.push tk_c
-      Token(tk_c)
-    end
-
-    @OP.def_rule("{") do
-      |op, io|
-      @indent += 1
-      if @lex_state != EXPR_END && @lex_state != EXPR_ARG
-	tk_c = TkLBRACE
-      else
-	tk_c = TkfLBRACE
-      end
-      @lex_state = EXPR_BEG
-      @indent_stack.push tk_c
-      Token(tk_c)
-    end
-
-    @OP.def_rule('\\') do
-      |op, io|
-      if getc == "\n"
-	@space_seen = true
-	@continue = true
-	Token(TkSPACE)
-      else
-	read_escape
-	Token("\\")
-      end
-    end
-
-    @OP.def_rule('%') do
-      |op, io|
-      if @lex_state == EXPR_BEG || @lex_state == EXPR_MID
-	identify_quotation
-      elsif peek(0) == '='
-	getc
-	Token(TkOPASGN, :%)
-      elsif @lex_state == EXPR_ARG and @space_seen and peek(0) !~ /\s/
-	identify_quotation
-      else
-	@lex_state = EXPR_BEG
-	Token("%") #))
-      end
-    end
-
-    @OP.def_rule('$') do
-      |op, io|
-      identify_gvar
-    end
-
-    @OP.def_rule('@') do
-      |op, io|
-      if peek(0) =~ /[\w@]/
-	ungetc
-	identify_identifier
-      else
-	Token("@")
-      end
-    end
-
-    #       @OP.def_rule("def", proc{|op, io| /\s/ =~ io.peek(0)}) do
-    # 	|op, io|
-    # 	@indent += 1
-    # 	@lex_state = EXPR_FNAME
-    # #	@lex_state = EXPR_END
-    # #	until @rests[0] == "\n" or @rests[0] == ";"
-    # #	  rests.shift
-    # #	end
-    #       end
-
-    @OP.def_rule("") do
-      |op, io|
-      printf "MATCH: start %s: %s\n", op, io.inspect if RubyLex.debug?
-      if peek(0) =~ /[0-9]/
-	t = identify_number
-      elsif peek(0) =~ /[^\x00-\/:-@\[-^`{-\x7F]/
-	t = identify_identifier
-      end
-      printf "MATCH: end %s: %s\n", op, io.inspect if RubyLex.debug?
-      t
-    end
-
-    p @OP if RubyLex.debug?
-  end
-
-  def identify_gvar
-    @lex_state = EXPR_END
-
-    case ch = getc
-    when /[~_*$?!@\/\\;,=:<>".]/   #"
-      Token(TkGVAR, "$" + ch)
-    when "-"
-      Token(TkGVAR, "$-" + getc)
-    when "&", "`", "'", "+"
-      Token(TkBACK_REF, "$"+ch)
-    when /[1-9]/
-      while getc =~ /[0-9]/; end
-      ungetc
-      Token(TkNTH_REF)
-    when /\w/
-      ungetc
-      ungetc
-      identify_identifier
-    else
-      ungetc
-      Token("$")
-    end
-  end
-
-  def identify_identifier
-    token = ""
-    if peek(0) =~ /[$@]/
-      token.concat(c = getc)
-      if c == "@" and peek(0) == "@"
-	token.concat getc
-      end
-    end
-
-    while (ch = getc) =~ /[^\x00-\/:-@\[-^`{-\x7F]/
-      print ":", ch, ":" if RubyLex.debug?
-      token.concat ch
-    end
-    ungetc
-
-    if (ch == "!" || ch == "?") && token[0,1] =~ /\w/ && peek(0) != "="
-      token.concat getc
-    end
-
-    # almost fix token
-
-    case token
-    when /^\$/
-      return Token(TkGVAR, token)
-    when /^\@\@/
-      @lex_state = EXPR_END
-      # p Token(TkCVAR, token)
-      return Token(TkCVAR, token)
-    when /^\@/
-      @lex_state = EXPR_END
-      return Token(TkIVAR, token)
-    end
-
-    if @lex_state != EXPR_DOT
-      print token, "\n" if RubyLex.debug?
-
-      token_c, *trans = TkReading2Token[token]
-      if token_c
-	# reserved word?
-
-	if (@lex_state != EXPR_BEG &&
-	    @lex_state != EXPR_FNAME &&
-	    trans[1])
-	  # modifiers
-	  token_c = TkSymbol2Token[trans[1]]
-	  @lex_state = trans[0]
-	else
-	  if @lex_state != EXPR_FNAME
-	    if ENINDENT_CLAUSE.include?(token)
-	      # check for ``class = val'' etc.
-	      valid = true
-	      case token
-	      when "class"
-		valid = false unless peek_match?(/^\s*(<<|\w|::)/)
-	      when "def"
-		valid = false if peek_match?(/^\s*(([+\-\/*&\|^]|<<|>>|\|\||\&\&)=|\&\&|\|\|)/)
-	      when "do"
-		valid = false if peek_match?(/^\s*([+\-\/*]?=|\*|<|>|\&)/)
-	      when *ENINDENT_CLAUSE
-		valid = false if peek_match?(/^\s*([+\-\/*]?=|\*|<|>|\&|\|)/)
-	      else
-		# no nothing
-	      end
-	      if valid
-		if token == "do"
-		  if ![TkFOR, TkWHILE, TkUNTIL].include?(@indent_stack.last)
-		    @indent += 1
-		    @indent_stack.push token_c
-		  end
-		else
-		  @indent += 1
-		  @indent_stack.push token_c
-		end
-#		p @indent_stack
-	      end
-
-	    elsif DEINDENT_CLAUSE.include?(token)
-	      @indent -= 1
-	      @indent_stack.pop
-	    end
-	    @lex_state = trans[0]
-	  else
-	    @lex_state = EXPR_END
-	  end
-	end
-	return Token(token_c, token)
-      end
-    end
-
-    if @lex_state == EXPR_FNAME
-      @lex_state = EXPR_END
-      if peek(0) == '='
-	token.concat getc
-      end
-    elsif @lex_state == EXPR_BEG || @lex_state == EXPR_DOT
-      @lex_state = EXPR_ARG
-    else
-      @lex_state = EXPR_END
-    end
-
-    if token[0, 1] =~ /[A-Z]/
-      return Token(TkCONSTANT, token)
-    elsif token[token.size - 1, 1] =~ /[!?]/
-      return Token(TkFID, token)
-    else
-      return Token(TkIDENTIFIER, token)
-    end
-  end
-
-  def identify_here_document
-    ch = getc
-#    if lt = PERCENT_LTYPE[ch]
-    if ch == "-"
-      ch = getc
-      indent = true
-    end
-    if /['"`]/ =~ ch
-      lt = ch
-      quoted = ""
-      while (c = getc) && c != lt
-	quoted.concat c
-      end
-    else
-      lt = '"'
-      quoted = ch.dup
-      while (c = getc) && c =~ /\w/
-	quoted.concat c
-      end
-      ungetc
-    end
-
-    ltback, @ltype = @ltype, lt
-    reserve = []
-    while ch = getc
-      reserve.push ch
-      if ch == "\\"
-	reserve.push ch = getc
-      elsif ch == "\n"
-	break
-      end
-    end
-
-    @here_header = false
-    while l = gets
-      l = l.sub(/(:?\r)?\n\z/, '')
-      if (indent ? l.strip : l) == quoted
- 	break
-      end
-    end
-
-    @here_header = true
-    @here_readed.concat reserve
-    while ch = reserve.pop
-      ungetc ch
-    end
-
-    @ltype = ltback
-    @lex_state = EXPR_END
-    Token(Ltype2Token[lt])
-  end
-
-  def identify_quotation
-    ch = getc
-    if lt = PERCENT_LTYPE[ch]
-      ch = getc
-    elsif ch =~ /\W/
-      lt = "\""
-    else
-      RubyLex.fail SyntaxError, "unknown type of %string"
-    end
-#     if ch !~ /\W/
-#       ungetc
-#       next
-#     end
-    #@ltype = lt
-    @quoted = ch unless @quoted = PERCENT_PAREN[ch]
-    identify_string(lt, @quoted)
-  end
-
-  def identify_number
-    @lex_state = EXPR_END
-
-    if peek(0) == "0" && peek(1) !~ /[.eE]/
-      getc
-      case peek(0)
-      when /[xX]/
-	ch = getc
-	match = /[0-9a-fA-F_]/
-      when /[bB]/
-	ch = getc
-	match = /[01_]/
-      when /[oO]/
-	ch = getc
-	match = /[0-7_]/
-      when /[dD]/
-	ch = getc
-	match = /[0-9_]/
-      when /[0-7]/
-	match = /[0-7_]/
-      when /[89]/
-	RubyLex.fail SyntaxError, "Invalid octal digit"
-      else
-	return Token(TkINTEGER)
-      end
-
-      len0 = true
-      non_digit = false
-      while ch = getc
-	if match =~ ch
-	  if ch == "_"
-	    if non_digit
-	      RubyLex.fail SyntaxError, "trailing `#{ch}' in number"
-	    else
-	      non_digit = ch
-	    end
-	  else
-	    non_digit = false
-	    len0 = false
-	  end
-	else
-	  ungetc
-	  if len0
-	    RubyLex.fail SyntaxError, "numeric literal without digits"
-	  end
-	  if non_digit
-	    RubyLex.fail SyntaxError, "trailing `#{non_digit}' in number"
-	  end
-	  break
-	end
-      end
-      return Token(TkINTEGER)
-    end
-
-    type = TkINTEGER
-    allow_point = true
-    allow_e = true
-    non_digit = false
-    while ch = getc
-      case ch
-      when /[0-9]/
-	non_digit = false
-      when "_"
-	non_digit = ch
-      when allow_point && "."
-	if non_digit
-	  RubyLex.fail SyntaxError, "trailing `#{non_digit}' in number"
-	end
-	type = TkFLOAT
-	if peek(0) !~ /[0-9]/
-	  type = TkINTEGER
-	  ungetc
-	  break
-	end
-	allow_point = false
-      when allow_e && "e", allow_e && "E"
-	if non_digit
-	  RubyLex.fail SyntaxError, "trailing `#{non_digit}' in number"
-	end
-	type = TkFLOAT
-	if peek(0) =~ /[+-]/
-	  getc
-	end
-	allow_e = false
-	allow_point = false
-	non_digit = ch
-      else
-	if non_digit
-	  RubyLex.fail SyntaxError, "trailing `#{non_digit}' in number"
-	end
-	ungetc
-	break
-      end
-    end
-    Token(type)
-  end
-
-  def identify_string(ltype, quoted = ltype)
-    @ltype = ltype
-    @quoted = quoted
-    subtype = nil
-    begin
-      nest = 0
-      while ch = getc
-	if @quoted == ch and nest == 0
-	  break
-	elsif @ltype != "'" && ch == "#" && peek(0) == "{"
-	  identify_string_dvar
-	elsif @ltype != "'" && @ltype != "]" && @ltype != ":" and ch == "#"
-	  subtype = true
-	elsif ch == '\\' and @ltype == "'" #'
-	  case ch = getc
-	  when "\\", "\n", "'"
-	  else
-	    ungetc
-	  end
-	elsif ch == '\\' #'
-	  read_escape
-	end
-	if PERCENT_PAREN.values.include?(@quoted)
-	  if PERCENT_PAREN[ch] == @quoted
-	    nest += 1
-	  elsif ch == @quoted
-	    nest -= 1
-	  end
-	end
-      end
-      if @ltype == "/"
-        while /[imxoesun]/ =~ peek(0)
-	  getc
-	end
-      end
-      if subtype
-	Token(DLtype2Token[ltype])
-      else
-	Token(Ltype2Token[ltype])
-      end
-    ensure
-      @ltype = nil
-      @quoted = nil
-      @lex_state = EXPR_END
-    end
-  end
-
-  def identify_string_dvar
-    begin
-      getc
-
-      reserve_continue = @continue
-      reserve_ltype = @ltype
-      reserve_indent = @indent
-      reserve_indent_stack = @indent_stack
-      reserve_state = @lex_state
-      reserve_quoted = @quoted
-
-      @ltype = nil
-      @quoted = nil
-      @indent = 0
-      @indent_stack = []
-      @lex_state = EXPR_BEG
-
-      loop do
-	@continue = false
-	prompt
-	tk = token
-	if @ltype or @continue or @indent > 0
-	  next
-	end
-	break if tk.kind_of?(TkRBRACE)
-      end
-    ensure
-      @continue = reserve_continue
-      @ltype = reserve_ltype
-      @indent = reserve_indent
-      @indent_stack = reserve_indent_stack
-      @lex_state = reserve_state
-      @quoted = reserve_quoted
-    end
-  end
-
-  def identify_comment
-    @ltype = "#"
-
-    while ch = getc
-#      if ch == "\\" #"
-#	read_escape
-#      end
-      if ch == "\n"
-	@ltype = nil
-	ungetc
-	break
-      end
-    end
-    return Token(TkCOMMENT)
-  end
-
-  def read_escape
-    case ch = getc
-    when "\n", "\r", "\f"
-    when "\\", "n", "t", "r", "f", "v", "a", "e", "b", "s" #"
-    when /[0-7]/
-      ungetc ch
-      3.times do
-	case ch = getc
-	when /[0-7]/
-	when nil
-	  break
-	else
-	  ungetc
-	  break
-	end
-      end
-
-    when "x"
-      2.times do
-	case ch = getc
-	when /[0-9a-fA-F]/
-	when nil
-	  break
-	else
-	  ungetc
-	  break
-	end
-      end
-
-    when "M"
-      if (ch = getc) != '-'
-	ungetc
-      else
-	if (ch = getc) == "\\" #"
-	  read_escape
-	end
-      end
-
-    when "C", "c" #, "^"
-      if ch == "C" and (ch = getc) != "-"
-	ungetc
-      elsif (ch = getc) == "\\" #"
-	read_escape
-      end
-    else
-      # other characters
-    end
-  end
-end
diff --git a/lib/irb/ruby-token.rb b/lib/irb/ruby-token.rb
deleted file mode 100644
index 531fb859ff..0000000000
--- a/lib/irb/ruby-token.rb
+++ /dev/null
@@ -1,265 +0,0 @@
-#
-#   irb/ruby-token.rb - ruby tokens
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-module RubyToken
-  EXPR_BEG = :EXPR_BEG
-  EXPR_MID = :EXPR_MID
-  EXPR_END = :EXPR_END
-  EXPR_ARG = :EXPR_ARG
-  EXPR_FNAME = :EXPR_FNAME
-  EXPR_DOT = :EXPR_DOT
-  EXPR_CLASS = :EXPR_CLASS
-
-  class Token
-    def initialize(seek, line_no, char_no)
-      @seek = seek
-      @line_no = line_no
-      @char_no = char_no
-    end
-    attr :seek, :line_no, :char_no
-  end
-
-  class TkNode < Token
-    def initialize(seek, line_no, char_no)
-      super
-    end
-    attr :node
-  end
-
-  class TkId < Token
-    def initialize(seek, line_no, char_no, name)
-      super(seek, line_no, char_no)
-      @name = name
-    end
-    attr :name
-  end
-
-  class TkVal < Token
-    def initialize(seek, line_no, char_no, value = nil)
-      super(seek, line_no, char_no)
-      @value = value
-    end
-    attr :value
-  end
-
-  class TkOp < Token
-    attr_accessor :name
-  end
-
-  class TkOPASGN < TkOp
-    def initialize(seek, line_no, char_no, op)
-      super(seek, line_no, char_no)
-      op = TkReading2Token[op][0] unless op.kind_of?(Symbol)
-      @op = op
-    end
-    attr :op
-  end
-
-  class TkUnknownChar < Token
-    def initialize(seek, line_no, char_no, id)
-      super(seek, line_no, char_no)
-      @name = name
-    end
-    attr :name
-  end
-
-  class TkError < Token
-  end
-
-  def Token(token, value = nil)
-    case token
-    when String
-      if (tk = TkReading2Token[token]).nil?
-	IRB.fail TkReading2TokenNoKey, token
-      end
-      tk = Token(tk[0], value)
-      if tk.kind_of?(TkOp)
-	tk.name = token
-      end
-      return tk
-    when Symbol
-      if (tk = TkSymbol2Token[token]).nil?
-	IRB.fail TkSymbol2TokenNoKey, token
-      end
-      return Token(tk[0], value)
-    else
-      if (token.ancestors & [TkId, TkVal, TkOPASGN, TkUnknownChar]).empty?
-	token.new(@prev_seek, @prev_line_no, @prev_char_no)
-      else
-	token.new(@prev_seek, @prev_line_no, @prev_char_no, value)
-      end
-    end
-  end
-
-  TokenDefinitions = [
-    [:TkCLASS,      TkId,  "class",  EXPR_CLASS],
-    [:TkMODULE,     TkId,  "module", EXPR_BEG],
-    [:TkDEF,	    TkId,  "def",    EXPR_FNAME],
-    [:TkUNDEF,      TkId,  "undef",  EXPR_FNAME],
-    [:TkBEGIN,      TkId,  "begin",  EXPR_BEG],
-    [:TkRESCUE,     TkId,  "rescue", EXPR_MID],
-    [:TkENSURE,     TkId,  "ensure", EXPR_BEG],
-    [:TkEND,	    TkId,  "end",    EXPR_END],
-    [:TkIF,         TkId,  "if",     EXPR_BEG, :TkIF_MOD],
-    [:TkUNLESS,     TkId,  "unless", EXPR_BEG, :TkUNLESS_MOD],
-    [:TkTHEN,	    TkId,  "then",   EXPR_BEG],
-    [:TkELSIF,      TkId,  "elsif",  EXPR_BEG],
-    [:TkELSE,	    TkId,  "else",   EXPR_BEG],
-    [:TkCASE,	    TkId,  "case",   EXPR_BEG],
-    [:TkWHEN,	    TkId,  "when",   EXPR_BEG],
-    [:TkWHILE,      TkId,  "while",  EXPR_BEG, :TkWHILE_MOD],
-    [:TkUNTIL,      TkId,  "until",  EXPR_BEG, :TkUNTIL_MOD],
-    [:TkFOR,	    TkId,  "for",    EXPR_BEG],
-    [:TkBREAK,      TkId,  "break",  EXPR_END],
-    [:TkNEXT,	    TkId,  "next",   EXPR_END],
-    [:TkREDO,	    TkId,  "redo",   EXPR_END],
-    [:TkRETRY,      TkId,  "retry",  EXPR_END],
-    [:TkIN,	    TkId,  "in",     EXPR_BEG],
-    [:TkDO,	    TkId,  "do",     EXPR_BEG],
-    [:TkRETURN,     TkId,  "return", EXPR_MID],
-    [:TkYIELD,      TkId,  "yield",  EXPR_END],
-    [:TkSUPER,      TkId,  "super",  EXPR_END],
-    [:TkSELF,	    TkId,  "self",   EXPR_END],
-    [:TkNIL, 	    TkId,  "nil",    EXPR_END],
-    [:TkTRUE,	    TkId,  "true",   EXPR_END],
-    [:TkFALSE,      TkId,  "false",  EXPR_END],
-    [:TkAND,	    TkId,  "and",    EXPR_BEG],
-    [:TkOR, 	    TkId,  "or",     EXPR_BEG],
-    [:TkNOT,	    TkId,  "not",    EXPR_BEG],
-    [:TkIF_MOD,     TkId],
-    [:TkUNLESS_MOD, TkId],
-    [:TkWHILE_MOD,  TkId],
-    [:TkUNTIL_MOD,  TkId],
-    [:TkALIAS,      TkId,  "alias",    EXPR_FNAME],
-    [:TkDEFINED,    TkId,  "defined?", EXPR_END],
-    [:TklBEGIN,     TkId,  "BEGIN",    EXPR_END],
-    [:TklEND,	    TkId,  "END",      EXPR_END],
-    [:Tk__LINE__,   TkId,  "__LINE__", EXPR_END],
-    [:Tk__FILE__,   TkId,  "__FILE__", EXPR_END],
-
-    [:TkIDENTIFIER, TkId],
-    [:TkFID,	    TkId],
-    [:TkGVAR,	    TkId],
-    [:TkCVAR,	    TkId],
-    [:TkIVAR,	    TkId],
-    [:TkCONSTANT,   TkId],
-
-    [:TkINTEGER,    TkVal],
-    [:TkFLOAT,      TkVal],
-    [:TkSTRING,     TkVal],
-    [:TkXSTRING,    TkVal],
-    [:TkREGEXP,     TkVal],
-    [:TkSYMBOL,     TkVal],
-
-    [:TkDSTRING,    TkNode],
-    [:TkDXSTRING,   TkNode],
-    [:TkDREGEXP,    TkNode],
-    [:TkNTH_REF,    TkNode],
-    [:TkBACK_REF,   TkNode],
-
-    [:TkUPLUS,      TkOp,   "+@"],
-    [:TkUMINUS,     TkOp,   "-@"],
-    [:TkPOW,	    TkOp,   "**"],
-    [:TkCMP,	    TkOp,   "<=>"],
-    [:TkEQ,	    TkOp,   "=="],
-    [:TkEQQ,	    TkOp,   "==="],
-    [:TkNEQ,	    TkOp,   "!="],
-    [:TkGEQ,	    TkOp,   ">="],
-    [:TkLEQ,	    TkOp,   "<="],
-    [:TkANDOP,      TkOp,   "&&"],
-    [:TkOROP,	    TkOp,   "||"],
-    [:TkMATCH,      TkOp,   "=~"],
-    [:TkNMATCH,     TkOp,   "!~"],
-    [:TkDOT2,	    TkOp,   ".."],
-    [:TkDOT3,	    TkOp,   "..."],
-    [:TkAREF,	    TkOp,   "[]"],
-    [:TkASET,	    TkOp,   "[]="],
-    [:TkLSHFT,      TkOp,   "<<"],
-    [:TkRSHFT,      TkOp,   ">>"],
-    [:TkCOLON2,     TkOp],
-    [:TkCOLON3,     TkOp],
-#   [:OPASGN,	    TkOp],               # +=, -=  etc. #
-    [:TkASSOC,      TkOp,   "=>"],
-    [:TkQUESTION,   TkOp,   "?"],	 #?
-    [:TkCOLON,      TkOp,   ":"],        #:
-
-    [:TkfLPAREN],         # func( #
-    [:TkfLBRACK],         # func[ #
-    [:TkfLBRACE],         # func{ #
-    [:TkSTAR],            # *arg
-    [:TkAMPER],           # &arg #
-    [:TkSYMBEG],          # :SYMBOL
-
-    [:TkGT,	    TkOp,   ">"],
-    [:TkLT,	    TkOp,   "<"],
-    [:TkPLUS,	    TkOp,   "+"],
-    [:TkMINUS,      TkOp,   "-"],
-    [:TkMULT,	    TkOp,   "*"],
-    [:TkDIV,	    TkOp,   "/"],
-    [:TkMOD,	    TkOp,   "%"],
-    [:TkBITOR,      TkOp,   "|"],
-    [:TkBITXOR,     TkOp,   "^"],
-    [:TkBITAND,     TkOp,   "&"],
-    [:TkBITNOT,     TkOp,   "~"],
-    [:TkNOTOP,      TkOp,   "!"],
-
-    [:TkBACKQUOTE,  TkOp,   "`"],
-
-    [:TkASSIGN,     Token,  "="],
-    [:TkDOT,	    Token,  "."],
-    [:TkLPAREN,     Token,  "("],  #(exp)
-    [:TkLBRACK,     Token,  "["],  #[arry]
-    [:TkLBRACE,     Token,  "{"],  #{hash}
-    [:TkRPAREN,     Token,  ")"],
-    [:TkRBRACK,     Token,  "]"],
-    [:TkRBRACE,     Token,  "}"],
-    [:TkCOMMA,      Token,  ","],
-    [:TkSEMICOLON,  Token,  ";"],
-
-    [:TkCOMMENT],
-    [:TkRD_COMMENT],
-    [:TkSPACE],
-    [:TkNL],
-    [:TkEND_OF_SCRIPT],
-
-    [:TkBACKSLASH,  TkUnknownChar,  "\\"],
-    [:TkAT,	    TkUnknownChar,  "@"],
-    [:TkDOLLAR,     TkUnknownChar,  "$"],
-  ]
-
-  # {reading => token_class}
-  # {reading => [token_class, *opt]}
-  TkReading2Token = {}
-  TkSymbol2Token = {}
-
-  def RubyToken.def_token(token_n, super_token = Token, reading = nil, *opts)
-    token_n = token_n.id2name if token_n.kind_of?(Symbol)
-    if RubyToken.const_defined?(token_n)
-      IRB.fail AlreadyDefinedToken, token_n
-    end
-    token_c = eval("class #{token_n} < #{super_token}; end; #{token_n}")
-
-    if reading
-      if TkReading2Token[reading]
-	IRB.fail TkReading2TokenDuplicateError, token_n, reading
-      end
-      if opts.empty?
-	TkReading2Token[reading] = [token_c]
-      else
-	TkReading2Token[reading] = [token_c].concat(opts)
-      end
-    end
-    TkSymbol2Token[token_n.intern] = token_c
-  end
-
-  for defs in TokenDefinitions
-    def_token(*defs)
-  end
-end
diff --git a/lib/irb/slex.rb b/lib/irb/slex.rb
deleted file mode 100644
index b395eaa475..0000000000
--- a/lib/irb/slex.rb
+++ /dev/null
@@ -1,282 +0,0 @@
-#
-#   irb/slex.rb - simple lex analyzer
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-
-require "e2mmap"
-require "irb/notifier"
-
-module IRB
-  class SLex
-    @RCS_ID='-$Id$-'
-
-    extend Exception2MessageMapper
-    def_exception :ErrNodeNothing, "node nothing"
-    def_exception :ErrNodeAlreadyExists, "node already exists"
-
-    DOUT = Notifier::def_notifier("SLex::")
-    D_WARN = DOUT::def_notifier(1, "Warn: ")
-    D_DEBUG = DOUT::def_notifier(2, "Debug: ")
-    D_DETAIL = DOUT::def_notifier(4, "Detail: ")
-
-    DOUT.level = Notifier::D_NOMSG
-
-    def initialize
-      @head = Node.new("")
-    end
-
-    def def_rule(token, preproc = nil, postproc = nil, &block)
-      D_DETAIL.pp token
-
-      postproc = block if block_given?
-      create(token, preproc, postproc)
-    end
-
-    def def_rules(*tokens, &block)
-      if block_given?
-	p = block
-      end
-      for token in tokens
-	def_rule(token, nil, p)
-      end
-    end
-
-    def preproc(token, proc)
-      node = search(token)
-      node.preproc=proc
-    end
-
-    #$BMW%A%'%C%/(B?
-    def postproc(token)
-      node = search(token, proc)
-      node.postproc=proc
-    end
-
-    def search(token)
-      @head.search(token.split(//))
-    end
-
-    def create(token, preproc = nil, postproc = nil)
-      @head.create_subnode(token.split(//), preproc, postproc)
-    end
-
-    def match(token)
-      case token
-      when Array
-      when String
-	return match(token.split(//))
-      else
-	return @head.match_io(token)
-      end
-      ret = @head.match(token)
-      D_DETAIL.exec_if{D_DEATIL.printf "match end: %s:%s\n", ret, token.inspect}
-      ret
-    end
-
-    def inspect
-      format("<SLex: @head = %s>", @head.inspect)
-    end
-
-    #----------------------------------------------------------------------
-    #
-    #   class Node -
-    #
-    #----------------------------------------------------------------------
-    class Node
-      # if postproc is nil, this node is an abstract node.
-      # if postproc is non-nil, this node is a real node.
-      def initialize(preproc = nil, postproc = nil)
-	@Tree = {}
-	@preproc = preproc
-	@postproc = postproc
-      end
-
-      attr_accessor :preproc
-      attr_accessor :postproc
-
-      def search(chrs, opt = nil)
-	return self if chrs.empty?
-	ch = chrs.shift
-	if node = @Tree[ch]
-	  node.search(chrs, opt)
-	else
-	  if opt
-	    chrs.unshift ch
-	    self.create_subnode(chrs)
-	  else
-	    SLex.fail ErrNodeNothing
-	  end
-	end
-      end
-
-      def create_subnode(chrs, preproc = nil, postproc = nil)
-	if chrs.empty?
-	  if @postproc
-	    D_DETAIL.pp node
-	    SLex.fail ErrNodeAlreadyExists
-	  else
-	    D_DEBUG.puts "change abstract node to real node."
-	    @preproc = preproc
-	    @postproc = postproc
-	  end
-	  return self
-	end
-
-	ch = chrs.shift
-	if node = @Tree[ch]
-	  if chrs.empty?
-	    if node.postproc
-	      DebugLogger.pp node
-	      DebugLogger.pp self
-	      DebugLogger.pp ch
-	      DebugLogger.pp chrs
-	      SLex.fail ErrNodeAlreadyExists
-	    else
-	      D_WARN.puts "change abstract node to real node"
-	      node.preproc = preproc
-	      node.postproc = postproc
-	    end
-	  else
-	    node.create_subnode(chrs, preproc, postproc)
-	  end
-	else
-	  if chrs.empty?
-	    node = Node.new(preproc, postproc)
-	  else
-	    node = Node.new
-	    node.create_subnode(chrs, preproc, postproc)
-	  end
-	  @Tree[ch] = node
-	end
-	node
-      end
-
-      #
-      # chrs: String
-      #       character array
-      #       io must have getc()/ungetc(); and ungetc() must be
-      #       able to be called arbitrary number of times.
-      #
-      def match(chrs, op = "")
-	D_DETAIL.print "match>: ", chrs, "op:", op, "\n"
-	if chrs.empty?
-	  if @preproc.nil? || @preproc.call(op, chrs)
-	    DOUT.printf(D_DETAIL, "op1: %s\n", op)
-	    @postproc.call(op, chrs)
-	  else
-	    nil
-	  end
-	else
-	  ch = chrs.shift
-	  if node = @Tree[ch]
-	    if ret = node.match(chrs, op+ch)
-	      return ret
-	    else
-	      chrs.unshift ch
-	      if @postproc and @preproc.nil? || @preproc.call(op, chrs)
-		DOUT.printf(D_DETAIL, "op2: %s\n", op.inspect)
-		ret = @postproc.call(op, chrs)
-		return ret
-	      else
-		return nil
-	      end
-	    end
-	  else
-	    chrs.unshift ch
-	    if @postproc and @preproc.nil? || @preproc.call(op, chrs)
-	      DOUT.printf(D_DETAIL, "op3: %s\n", op)
-	      @postproc.call(op, chrs)
-	      return ""
-	    else
-	      return nil
-	    end
-	  end
-	end
-      end
-
-      def match_io(io, op = "")
-	if op == ""
-	  ch = io.getc
-	  if ch == nil
-	    return nil
-	  end
-	else
-	  ch = io.getc_of_rests
-	end
-	if ch.nil?
-	  if @preproc.nil? || @preproc.call(op, io)
-	    D_DETAIL.printf("op1: %s\n", op)
-	    @postproc.call(op, io)
-	  else
-	    nil
-	  end
-	else
-	  if node = @Tree[ch]
-	    if ret = node.match_io(io, op+ch)
-	      ret
-	    else
-	      io.ungetc ch
-	      if @postproc and @preproc.nil? || @preproc.call(op, io)
-		DOUT.exec_if{D_DETAIL.printf "op2: %s\n", op.inspect}
-		@postproc.call(op, io)
-	      else
-		nil
-	      end
-	    end
-	  else
-	    io.ungetc ch
-	    if @postproc and @preproc.nil? || @preproc.call(op, io)
-	      D_DETAIL.printf("op3: %s\n", op)
-	      @postproc.call(op, io)
-	    else
-	      nil
-	    end
-	  end
-	end
-      end
-    end
-  end
-end
-
-if $0 == __FILE__
-  #    Tracer.on
-  case $1
-  when "1"
-    tr = SLex.new
-    print "0: ", tr.inspect, "\n"
-    tr.def_rule("=") {print "=\n"}
-    print "1: ", tr.inspect, "\n"
-    tr.def_rule("==") {print "==\n"}
-    print "2: ", tr.inspect, "\n"
-
-    print "case 1:\n"
-    print tr.match("="), "\n"
-    print "case 2:\n"
-    print tr.match("=="), "\n"
-    print "case 3:\n"
-    print tr.match("=>"), "\n"
-
-  when "2"
-    tr = SLex.new
-    print "0: ", tr.inspect, "\n"
-    tr.def_rule("=") {print "=\n"}
-    print "1: ", tr.inspect, "\n"
-    tr.def_rule("==", proc{false}) {print "==\n"}
-    print "2: ", tr.inspect, "\n"
-
-    print "case 1:\n"
-    print tr.match("="), "\n"
-    print "case 2:\n"
-    print tr.match("=="), "\n"
-    print "case 3:\n"
-    print tr.match("=>"), "\n"
-  end
-  exit
-end
-
diff --git a/lib/irb/src_encoding.rb b/lib/irb/src_encoding.rb
deleted file mode 100644
index 958cef104c..0000000000
--- a/lib/irb/src_encoding.rb
+++ /dev/null
@@ -1,4 +0,0 @@
-# DO NOT WRITE ANY MAGIC COMMENT HERE.
-def default_src_encoding
-  return __ENCODING__
-end
diff --git a/lib/irb/version.rb b/lib/irb/version.rb
deleted file mode 100644
index 621a127ebd..0000000000
--- a/lib/irb/version.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-#
-#   irb/version.rb - irb version definition file
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ishitsuka.com)
-#
-# --
-#
-#
-#
-
-module IRB
-  @RELEASE_VERSION = "0.9.6"
-  @LAST_UPDATE_DATE = "09/06/30"
-end
diff --git a/lib/irb/workspace.rb b/lib/irb/workspace.rb
deleted file mode 100644
index edc0d3b147..0000000000
--- a/lib/irb/workspace.rb
+++ /dev/null
@@ -1,108 +0,0 @@
-#
-#   irb/workspace-binding.rb -
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-module IRB
-  class WorkSpace
-    # create new workspace. set self to main if specified, otherwise
-    # inherit main from TOPLEVEL_BINDING.
-    def initialize(*main)
-      if main[0].kind_of?(Binding)
-	@binding = main.shift
-      elsif IRB.conf[:SINGLE_IRB]
-	@binding = TOPLEVEL_BINDING
-      else
-	case IRB.conf[:CONTEXT_MODE]
-	when 0	# binding in proc on TOPLEVEL_BINDING
-	  @binding = eval("proc{binding}.call",
-		      TOPLEVEL_BINDING,
-		      __FILE__,
-		      __LINE__)
-	when 1	# binding in loaded file
-	  require "tempfile"
-	  f = Tempfile.open("irb-binding")
-	  f.print <<EOF
-	  $binding = binding
-EOF
-	  f.close
-	  load f.path
-	  @binding = $binding
-
-	when 2	# binding in loaded file(thread use)
-	  unless defined? BINDING_QUEUE
-	    require "thread"
-
-	    IRB.const_set("BINDING_QUEUE", SizedQueue.new(1))
-	    Thread.abort_on_exception = true
-	    Thread.start do
-	      eval "require \"irb/ws-for-case-2\"", TOPLEVEL_BINDING, __FILE__, __LINE__
-	    end
-	    Thread.pass
-	  end
-	  @binding = BINDING_QUEUE.pop
-
-	when 3	# binging in function on TOPLEVEL_BINDING(default)
-	  @binding = eval("def irb_binding; binding; end; irb_binding",
-		      TOPLEVEL_BINDING,
-		      __FILE__,
-		      __LINE__ - 3)
-	end
-      end
-      if main.empty?
-	@main = eval("self", @binding)
-      else
-	@main = main[0]
-	IRB.conf[:__MAIN__] = @main
-	case @main
-	when Module
-	  @binding = eval("IRB.conf[:__MAIN__].module_eval('binding', __FILE__, __LINE__)", @binding, __FILE__, __LINE__)
-	else
-	  begin
-	    @binding = eval("IRB.conf[:__MAIN__].instance_eval('binding', __FILE__, __LINE__)", @binding, __FILE__, __LINE__)
-	  rescue TypeError
-	    IRB.fail CantChangeBinding, @main.inspect
-	  end
-	end
-      end
-      eval("_=nil", @binding)
-    end
-
-    attr_reader :binding
-    attr_reader :main
-
-    def evaluate(context, statements, file = __FILE__, line = __LINE__)
-      eval(statements, @binding, file, line)
-    end
-
-    # error message manipulator
-    def filter_backtrace(bt)
-      case IRB.conf[:CONTEXT_MODE]
-      when 0
-	return nil if bt =~ /\(irb_local_binding\)/
-      when 1
-	if(bt =~ %r!/tmp/irb-binding! or
-	   bt =~ %r!irb/.*\.rb! or
-	   bt =~ /irb\.rb/)
-	  return nil
-	end
-      when 2
-	return nil if bt =~ /irb\/.*\.rb/
-	return nil if bt =~ /irb\.rb/
-      when 3
-	return nil if bt =~ /irb\/.*\.rb/
-	return nil if bt =~ /irb\.rb/
-	bt = bt.sub(/:\s*in `irb_binding'/, '')
-      end
-      bt
-    end
-
-    def IRB.delete_caller
-    end
-  end
-end
diff --git a/lib/irb/ws-for-case-2.rb b/lib/irb/ws-for-case-2.rb
deleted file mode 100644
index 9f3af49f30..0000000000
--- a/lib/irb/ws-for-case-2.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-#
-#   irb/ws-for-case-2.rb -
-#   	$Release Version: 0.9.6$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-# --
-#
-#
-#
-
-while true
-  IRB::BINDING_QUEUE.push _ = binding
-end
diff --git a/lib/irb/xmp.rb b/lib/irb/xmp.rb
deleted file mode 100644
index bcef964020..0000000000
--- a/lib/irb/xmp.rb
+++ /dev/null
@@ -1,97 +0,0 @@
-#
-#   xmp.rb - irb version of gotoken xmp
-#   	$Release Version: 0.9$
-#   	$Revision$
-#   	by Keiju ISHITSUKA(Nippon Rational Inc.)
-#
-# --
-#
-#
-#
-
-require "irb"
-require "irb/frame"
-
-class XMP
-  @RCS_ID='-$Id$-'
-
-  def initialize(bind = nil)
-    IRB.init_config(nil)
-    #IRB.parse_opts
-    #IRB.load_modules
-
-    IRB.conf[:PROMPT_MODE] = :XMP
-
-    bind = IRB::Frame.top(1) unless bind
-    ws = IRB::WorkSpace.new(bind)
-    @io = StringInputMethod.new
-    @irb = IRB::Irb.new(ws, @io)
-    @irb.context.ignore_sigint = false
-
-#    IRB.conf[:IRB_RC].call(@irb.context) if IRB.conf[:IRB_RC]
-    IRB.conf[:MAIN_CONTEXT] = @irb.context
-  end
-
-  def puts(exps)
-    @io.puts exps
-
-    if @irb.context.ignore_sigint
-      begin
-	trap_proc_b = trap("SIGINT"){@irb.signal_handle}
-	catch(:IRB_EXIT) do
-	  @irb.eval_input
-	end
-      ensure
-	trap("SIGINT", trap_proc_b)
-      end
-    else
-      catch(:IRB_EXIT) do
-	@irb.eval_input
-      end
-    end
-  end
-
-  class StringInputMethod < IRB::InputMethod
-    def initialize
-      super
-      @exps = []
-    end
-
-    def eof?
-      @exps.empty?
-    end
-
-    def gets
-      while l = @exps.shift
-	next if /^\s+$/ =~ l
-	l.concat "\n"
-	print @prompt, l
-	break
-      end
-      l
-    end
-
-    def puts(exps)
-      if @encoding and exps.encoding != @encoding
-	enc = Encoding.compatible?(@exps.join("\n"), exps)
-	if enc.nil?
-	  raise Encoding::CompatibilityError, "Encoding in which the passed expression is encoded is not compatible to the preceding's one"
-	else
-	  @encoding = enc
-	end
-      else
-	@encoding = exps.encoding
-      end
-      @exps.concat exps.split(/\n/)
-    end
-
-    attr_reader :encoding
-  end
-end
-
-def xmp(exps, bind = nil)
-  bind = IRB::Frame.top(1) unless bind
-  xmp = XMP.new(bind)
-  xmp.puts exps
-  xmp
-end
diff --git a/lib/logger.rb b/lib/logger.rb
deleted file mode 100644
index 6092959399..0000000000
--- a/lib/logger.rb
+++ /dev/null
@@ -1,801 +0,0 @@
-# logger.rb - simple logging utility
-# Copyright (C) 2000-2003, 2005, 2008, 2011  NAKAMURA, Hiroshi <nahi@ruby-lang.org>.
-#
-# Documentation:: NAKAMURA, Hiroshi and Gavin Sinclair
-# License::
-#   You can redistribute it and/or modify it under the same terms of Ruby's
-#   license; either the dual license version in 2003, or any later version.
-# Revision:: $Id$
-#
-# A simple system for logging messages.  See Logger for more documentation.
-
-require 'monitor'
-
-# == Description
-#
-# The Logger class provides a simple but sophisticated logging utility that
-# you can use to output messages.
-#
-# The messages have associated levels, such as +INFO+ or +ERROR+ that indicate
-# their importance.  You can then give the Logger a level, and only messages
-# at that level of higher will be printed.
-#
-# The levels are:
-#
-# +FATAL+:: an unhandleable error that results in a program crash
-# +ERROR+:: a handleable error condition
-# +WARN+::  a warning
-# +INFO+::  generic (useful) information about system operation
-# +DEBUG+:: low-level information for developers
-#
-# For instance, in a production system, you may have your Logger set to
-# +INFO+ or even +WARN+
-# When you are developing the system, however, you probably
-# want to know about the program's internal state, and would set the Logger to
-# +DEBUG+.
-#
-# *Note*: Logger does not escape or sanitize any messages passed to it.
-# Developers should be aware of when potentially malicious data (user-input)
-# is passed to Logger, and manually escape the untrusted data:
-#
-#   logger.info("User-input: #{input.dump}")
-#   logger.info("User-input: %p" % input)
-#
-# You can use #formatter= for escaping all data.
-#
-#   original_formatter = Logger::Formatter.new
-#   logger.formatter = proc { |severity, datetime, progname, msg|
-#     original_formatter.call(severity, datetime, progname, msg.dump)
-#   }
-#   logger.info(input)
-#
-# === Example
-#
-# This creates a logger to the standard output stream, with a level of +WARN+
-#
-#   log = Logger.new(STDOUT)
-#   log.level = Logger::WARN
-#
-#   log.debug("Created logger")
-#   log.info("Program started")
-#   log.warn("Nothing to do!")
-#
-#   begin
-#     File.each_line(path) do |line|
-#       unless line =~ /^(\w+) = (.*)$/
-#         log.error("Line in wrong format: #{line}")
-#       end
-#     end
-#   rescue => err
-#     log.fatal("Caught exception; exiting")
-#     log.fatal(err)
-#   end
-#
-# Because the Logger's level is set to +WARN+, only the warning, error, and
-# fatal messages are recorded.  The debug and info messages are silently
-# discarded.
-#
-# === Features
-#
-# There are several interesting features that Logger provides, like
-# auto-rolling of log files, setting the format of log messages, and
-# specifying a program name in conjunction with the message.  The next section
-# shows you how to achieve these things.
-#
-#
-# == HOWTOs
-#
-# === How to create a logger
-#
-# The options below give you various choices, in more or less increasing
-# complexity.
-#
-# 1. Create a logger which logs messages to STDERR/STDOUT.
-#
-#      logger = Logger.new(STDERR)
-#      logger = Logger.new(STDOUT)
-#
-# 2. Create a logger for the file which has the specified name.
-#
-#      logger = Logger.new('logfile.log')
-#
-# 3. Create a logger for the specified file.
-#
-#      file = File.open('foo.log', File::WRONLY | File::APPEND)
-#      # To create new (and to remove old) logfile, add File::CREAT like;
-#      #   file = open('foo.log', File::WRONLY | File::APPEND | File::CREAT)
-#      logger = Logger.new(file)
-#
-# 4. Create a logger which ages logfile once it reaches a certain size.  Leave
-#    10 "old log files" and each file is about 1,024,000 bytes.
-#
-#      logger = Logger.new('foo.log', 10, 1024000)
-#
-# 5. Create a logger which ages logfile daily/weekly/monthly.
-#
-#      logger = Logger.new('foo.log', 'daily')
-#      logger = Logger.new('foo.log', 'weekly')
-#      logger = Logger.new('foo.log', 'monthly')
-#
-# === How to log a message
-#
-# Notice the different methods (+fatal+, +error+, +info+) being used to log
-# messages of various levels?  Other methods in this family are +warn+ and
-# +debug+.  +add+ is used below to log a message of an arbitrary (perhaps
-# dynamic) level.
-#
-# 1. Message in block.
-#
-#      logger.fatal { "Argument 'foo' not given." }
-#
-# 2. Message as a string.
-#
-#      logger.error "Argument #{ @foo } mismatch."
-#
-# 3. With progname.
-#
-#      logger.info('initialize') { "Initializing..." }
-#
-# 4. With severity.
-#
-#      logger.add(Logger::FATAL) { 'Fatal error!' }
-#
-# The block form allows you to create potentially complex log messages,
-# but to delay their evaluation until and unless the message is
-# logged.  For example, if we have the following:
-#
-#     logger.debug { "This is a " + potentially + " expensive operation" }
-#
-# If the logger's level is +INFO+ or higher, no debug messages will be logged,
-# and the entire block will not even be evaluated.  Compare to this:
-#
-#     logger.debug("This is a " + potentially + " expensive operation")
-#
-# Here, the string concatenation is done every time, even if the log
-# level is not set to show the debug message.
-#
-# === How to close a logger
-#
-#      logger.close
-#
-# === Setting severity threshold
-#
-# 1. Original interface.
-#
-#      logger.sev_threshold = Logger::WARN
-#
-# 2. Log4r (somewhat) compatible interface.
-#
-#      logger.level = Logger::INFO
-#
-#      DEBUG < INFO < WARN < ERROR < FATAL < UNKNOWN
-#
-#
-# == Format
-#
-# Log messages are rendered in the output stream in a certain format by
-# default.  The default format and a sample are shown below:
-#
-# Log format:
-#   SeverityID, [Date Time mSec #pid] SeverityLabel -- ProgName: message
-#
-# Log sample:
-#   I, [Wed Mar 03 02:34:24 JST 1999 895701 #19074]  INFO -- Main: info.
-#
-# You may change the date and time format via #datetime_format=
-#
-#   logger.datetime_format = "%Y-%m-%d %H:%M:%S"
-#         # e.g. "2004-01-03 00:54:26"
-#
-# Or, you may change the overall format with #formatter= method.
-#
-#   logger.formatter = proc do |severity, datetime, progname, msg|
-#     "#{datetime}: #{msg}\n"
-#   end
-#   # e.g. "Thu Sep 22 08:51:08 GMT+9:00 2005: hello world"
-#
-class Logger
-  VERSION = "1.2.7"
-  _, name, rev = %w$Id$
-  if name
-    name = name.chomp(",v")
-  else
-    name = File.basename(__FILE__)
-  end
-  rev ||= "v#{VERSION}"
-  ProgName = "#{name}/#{rev}"
-
-  class Error < RuntimeError # :nodoc:
-  end
-  # not used after 1.2.7. just for compat.
-  class ShiftingError < Error # :nodoc:
-  end
-
-  # Logging severity.
-  module Severity
-    # Low-level information, mostly for developers
-    DEBUG = 0
-    # generic, useful information about system operation
-    INFO = 1
-    # a warning
-    WARN = 2
-    # a handleable error condition
-    ERROR = 3
-    # an unhandleable error that results in a program crash
-    FATAL = 4
-    # an unknown message that should always be logged
-    UNKNOWN = 5
-  end
-  include Severity
-
-  # Logging severity threshold (e.g. <tt>Logger::INFO</tt>).
-  attr_accessor :level
-
-  # program name to include in log messages.
-  attr_accessor :progname
-
-  # Set date-time format.
-  #
-  # +datetime_format+:: A string suitable for passing to +strftime+.
-  def datetime_format=(datetime_format)
-    @default_formatter.datetime_format = datetime_format
-  end
-
-  # Returns the date format being used.  See #datetime_format=
-  def datetime_format
-    @default_formatter.datetime_format
-  end
-
-  # Logging formatter, as a +Proc+ that will take four arguments and
-  # return the formatted message. The arguments are:
-  #
-  # +severity+:: The Severity of the log message
-  # +time+:: A Time instance representing when the message was logged
-  # +progname+:: The #progname configured, or passed to the logger method
-  # +msg+:: The _Object_ the user passed to the log message; not necessarily a
-  #         String.
-  #
-  # The block should return an Object that can be written to the logging
-  # device via +write+.  The default formatter is used when no formatter is
-  # set.
-  attr_accessor :formatter
-
-  alias sev_threshold level
-  alias sev_threshold= level=
-
-  # Returns +true+ iff the current severity level allows for the printing of
-  # +DEBUG+ messages.
-  def debug?; @level <= DEBUG; end
-
-  # Returns +true+ iff the current severity level allows for the printing of
-  # +INFO+ messages.
-  def info?; @level <= INFO; end
-
-  # Returns +true+ iff the current severity level allows for the printing of
-  # +WARN+ messages.
-  def warn?; @level <= WARN; end
-
-  # Returns +true+ iff the current severity level allows for the printing of
-  # +ERROR+ messages.
-  def error?; @level <= ERROR; end
-
-  # Returns +true+ iff the current severity level allows for the printing of
-  # +FATAL+ messages.
-  def fatal?; @level <= FATAL; end
-
-  #
-  # === Synopsis
-  #
-  #   Logger.new(name, shift_age = 7, shift_size = 1048576)
-  #   Logger.new(name, shift_age = 'weekly')
-  #
-  # === Args
-  #
-  # +logdev+::
-  #   The log device.  This is a filename (String) or IO object (typically
-  #   +STDOUT+, +STDERR+, or an open file).
-  # +shift_age+::
-  #   Number of old log files to keep, *or* frequency of rotation (+daily+,
-  #   +weekly+ or +monthly+).
-  # +shift_size+::
-  #   Maximum logfile size (only applies when +shift_age+ is a number).
-  #
-  # === Description
-  #
-  # Create an instance.
-  #
-  def initialize(logdev, shift_age = 0, shift_size = 1048576)
-    @progname = nil
-    @level = DEBUG
-    @default_formatter = Formatter.new
-    @formatter = nil
-    @logdev = nil
-    if logdev
-      @logdev = LogDevice.new(logdev, :shift_age => shift_age,
-        :shift_size => shift_size)
-    end
-  end
-
-  #
-  # === Synopsis
-  #
-  #   Logger#add(severity, message = nil, progname = nil) { ... }
-  #
-  # === Args
-  #
-  # +severity+::
-  #   Severity.  Constants are defined in Logger namespace: +DEBUG+, +INFO+,
-  #   +WARN+, +ERROR+, +FATAL+, or +UNKNOWN+.
-  # +message+::
-  #   The log message.  A String or Exception.
-  # +progname+::
-  #   Program name string.  Can be omitted.  Treated as a message if no
-  #   +message+ and +block+ are given.
-  # +block+::
-  #   Can be omitted.  Called to get a message string if +message+ is nil.
-  #
-  # === Return
-  #
-  # +true+ if successful, +false+ otherwise.
-  #
-  # When the given severity is not high enough (for this particular logger), log
-  # no message, and return +true+.
-  #
-  # === Description
-  #
-  # Log a message if the given severity is high enough.  This is the generic
-  # logging method.  Users will be more inclined to use #debug, #info, #warn,
-  # #error, and #fatal.
-  #
-  # <b>Message format</b>: +message+ can be any object, but it has to be
-  # converted to a String in order to log it.  Generally, +inspect+ is used
-  # if the given object is not a String.
-  # A special case is an +Exception+ object, which will be printed in detail,
-  # including message, class, and backtrace.  See #msg2str for the
-  # implementation if required.
-  #
-  # === Bugs
-  #
-  # * Logfile is not locked.
-  # * Append open does not need to lock file.
-  # * If the OS which supports multi I/O, records possibly be mixed.
-  #
-  def add(severity, message = nil, progname = nil, &block)
-    severity ||= UNKNOWN
-    if @logdev.nil? or severity < @level
-      return true
-    end
-    progname ||= @progname
-    if message.nil?
-      if block_given?
-        message = yield
-      else
-        message = progname
-        progname = @progname
-      end
-    end
-    @logdev.write(
-      format_message(format_severity(severity), Time.now, progname, message))
-    true
-  end
-  alias log add
-
-  #
-  # Dump given message to the log device without any formatting.  If no log
-  # device exists, return +nil+.
-  #
-  def <<(msg)
-    unless @logdev.nil?
-      @logdev.write(msg)
-    end
-  end
-
-  #
-  # Log a +DEBUG+ message.
-  #
-  # See #info for more information.
-  #
-  def debug(progname = nil, &block)
-    add(DEBUG, nil, progname, &block)
-  end
-
-  #
-  # :call-seq:
-  #   info(message)
-  #   info(progname,&block)
-  #
-  # Log an +INFO+ message.
-  #
-  # +message+:: the message to log; does not need to be a String
-  # +progname+:: in the block form, this is the #progname to use in the
-  #              the log message.  The default can be set with #progname=
-  # <tt>&block</tt>:: evaluates to the message to log.  This is not evaluated
-  #                   unless the logger's level is sufficient
-  #                   to log the message.  This allows you to create
-  #                   potentially expensive logging messages that are
-  #                   only called when the logger is configured to show them.
-  #
-  # === Examples
-  #
-  #   logger.info("MainApp") { "Received connection from #{ip}" }
-  #   # ...
-  #   logger.info "Waiting for input from user"
-  #   # ...
-  #   logger.info { "User typed #{input}" }
-  #
-  # You'll probably stick to the second form above, unless you want to provide a
-  # program name (which you can do with #progname= as well).
-  #
-  # === Return
-  #
-  # See #add.
-  #
-  def info(progname = nil, &block)
-    add(INFO, nil, progname, &block)
-  end
-
-  #
-  # Log a +WARN+ message.
-  #
-  # See #info for more information.
-  #
-  def warn(progname = nil, &block)
-    add(WARN, nil, progname, &block)
-  end
-
-  #
-  # Log an +ERROR+ message.
-  #
-  # See #info for more information.
-  #
-  def error(progname = nil, &block)
-    add(ERROR, nil, progname, &block)
-  end
-
-  #
-  # Log a +FATAL+ message.
-  #
-  # See #info for more information.
-  #
-  def fatal(progname = nil, &block)
-    add(FATAL, nil, progname, &block)
-  end
-
-  #
-  # Log an +UNKNOWN+ message.  This will be printed no matter what the logger's
-  # level.
-  #
-  # See #info for more information.
-  #
-  def unknown(progname = nil, &block)
-    add(UNKNOWN, nil, progname, &block)
-  end
-
-  #
-  # Close the logging device.
-  #
-  def close
-    @logdev.close if @logdev
-  end
-
-private
-
-  # Severity label for logging. (max 5 char)
-  SEV_LABEL = %w(DEBUG INFO WARN ERROR FATAL ANY)
-
-  def format_severity(severity)
-    SEV_LABEL[severity] || 'ANY'
-  end
-
-  def format_message(severity, datetime, progname, msg)
-    (@formatter || @default_formatter).call(severity, datetime, progname, msg)
-  end
-
-
-  # Default formatter for log messages
-  class Formatter
-    Format = "%s, [%s#%d] %5s -- %s: %s\n"
-
-    attr_accessor :datetime_format
-
-    def initialize
-      @datetime_format = nil
-    end
-
-    def call(severity, time, progname, msg)
-      Format % [severity[0..0], format_datetime(time), $$, severity, progname,
-        msg2str(msg)]
-    end
-
-  private
-
-    def format_datetime(time)
-      if @datetime_format.nil?
-        time.strftime("%Y-%m-%dT%H:%M:%S.") << "%06d " % time.usec
-      else
-        time.strftime(@datetime_format)
-      end
-    end
-
-    def msg2str(msg)
-      case msg
-      when ::String
-        msg
-      when ::Exception
-        "#{ msg.message } (#{ msg.class })\n" <<
-          (msg.backtrace || []).join("\n")
-      else
-        msg.inspect
-      end
-    end
-  end
-
-
-  # Device used for logging messages.
-  class LogDevice
-    attr_reader :dev
-    attr_reader :filename
-
-    class LogDeviceMutex
-      include MonitorMixin
-    end
-
-    def initialize(log = nil, opt = {})
-      @dev = @filename = @shift_age = @shift_size = nil
-      @mutex = LogDeviceMutex.new
-      if log.respond_to?(:write) and log.respond_to?(:close)
-        @dev = log
-      else
-        @dev = open_logfile(log)
-        @dev.sync = true
-        @filename = log
-        @shift_age = opt[:shift_age] || 7
-        @shift_size = opt[:shift_size] || 1048576
-      end
-    end
-
-    def write(message)
-      begin
-        @mutex.synchronize do
-          if @shift_age and @dev.respond_to?(:stat)
-            begin
-              check_shift_log
-            rescue
-              warn("log shifting failed. #{$!}")
-            end
-          end
-          begin
-            @dev.write(message)
-          rescue
-            warn("log writing failed. #{$!}")
-          end
-        end
-      rescue Exception => ignored
-        warn("log writing failed. #{ignored}")
-      end
-    end
-
-    def close
-      begin
-        @mutex.synchronize do
-          @dev.close rescue nil
-        end
-      rescue Exception
-        @dev.close rescue nil
-      end
-    end
-
-  private
-
-    def open_logfile(filename)
-      if (FileTest.exist?(filename))
-        open(filename, (File::WRONLY | File::APPEND))
-      else
-        create_logfile(filename)
-      end
-    end
-
-    def create_logfile(filename)
-      logdev = open(filename, (File::WRONLY | File::APPEND | File::CREAT))
-      logdev.sync = true
-      add_log_header(logdev)
-      logdev
-    end
-
-    def add_log_header(file)
-      file.write(
-        "# Logfile created on %s by %s\n" % [Time.now.to_s, Logger::ProgName]
-      )
-    end
-
-    SiD = 24 * 60 * 60
-
-    def check_shift_log
-      if @shift_age.is_a?(Integer)
-        # Note: always returns false if '0'.
-        if @filename && (@shift_age > 0) && (@dev.stat.size > @shift_size)
-          shift_log_age
-        end
-      else
-        now = Time.now
-        period_end = previous_period_end(now)
-        if @dev.stat.mtime <= period_end
-          shift_log_period(period_end)
-        end
-      end
-    end
-
-    def shift_log_age
-      (@shift_age-3).downto(0) do |i|
-        if FileTest.exist?("#{@filename}.#{i}")
-          File.rename("#{@filename}.#{i}", "#{@filename}.#{i+1}")
-        end
-      end
-      @dev.close rescue nil
-      File.rename("#{@filename}", "#{@filename}.0")
-      @dev = create_logfile(@filename)
-      return true
-    end
-
-    def shift_log_period(period_end)
-      postfix = period_end.strftime("%Y%m%d") # YYYYMMDD
-      age_file = "#{@filename}.#{postfix}"
-      if FileTest.exist?(age_file)
-        # try to avoid filename crash caused by Timestamp change.
-        idx = 0
-        # .99 can be overridden; avoid too much file search with 'loop do'
-        while idx < 100
-          idx += 1
-          age_file = "#{@filename}.#{postfix}.#{idx}"
-          break unless FileTest.exist?(age_file)
-        end
-      end
-      @dev.close rescue nil
-      File.rename("#{@filename}", age_file)
-      @dev = create_logfile(@filename)
-      return true
-    end
-
-    def previous_period_end(now)
-      case @shift_age
-      when /^daily$/
-        eod(now - 1 * SiD)
-      when /^weekly$/
-        eod(now - ((now.wday + 1) * SiD))
-      when /^monthly$/
-        eod(now - now.mday * SiD)
-      else
-        now
-      end
-    end
-
-    def eod(t)
-      Time.mktime(t.year, t.month, t.mday, 23, 59, 59)
-    end
-  end
-
-
-  #
-  # == Description
-  #
-  # Application -- Add logging support to your application.
-  #
-  # == Usage
-  #
-  # 1. Define your application class as a sub-class of this class.
-  # 2. Override 'run' method in your class to do many things.
-  # 3. Instantiate it and invoke 'start'.
-  #
-  # == Example
-  #
-  #   class FooApp < Application
-  #     def initialize(foo_app, application_specific, arguments)
-  #       super('FooApp') # Name of the application.
-  #     end
-  #
-  #     def run
-  #       ...
-  #       log(WARN, 'warning', 'my_method1')
-  #       ...
-  #       @log.error('my_method2') { 'Error!' }
-  #       ...
-  #     end
-  #   end
-  #
-  #   status = FooApp.new(....).start
-  #
-  class Application
-    include Logger::Severity
-
-    # Name of the application given at initialize.
-    attr_reader :appname
-
-    #
-    # == Synopsis
-    #
-    #   Application.new(appname = '')
-    #
-    # == Args
-    #
-    # +appname+:: Name of the application.
-    #
-    # == Description
-    #
-    # Create an instance.  Log device is +STDERR+ by default.  This can be
-    # changed with #set_log.
-    #
-    def initialize(appname = nil)
-      @appname = appname
-      @log = Logger.new(STDERR)
-      @log.progname = @appname
-      @level = @log.level
-    end
-
-    #
-    # Start the application.  Return the status code.
-    #
-    def start
-      status = -1
-      begin
-        log(INFO, "Start of #{ @appname }.")
-        status = run
-      rescue
-        log(FATAL, "Detected an exception. Stopping ... #{$!} (#{$!.class})\n" << $@.join("\n"))
-      ensure
-        log(INFO, "End of #{ @appname }. (status: #{ status.to_s })")
-      end
-      status
-    end
-
-    # Logger for this application.  See the class Logger for an explanation.
-    def logger
-      @log
-    end
-
-    #
-    # Sets the logger for this application.  See the class Logger for an
-    # explanation.
-    #
-    def logger=(logger)
-      @log = logger
-      @log.progname = @appname
-      @log.level = @level
-    end
-
-    #
-    # Sets the log device for this application.  See <tt>Logger.new</tt> for
-    # an explanation of the arguments.
-    #
-    def set_log(logdev, shift_age = 0, shift_size = 1024000)
-      @log = Logger.new(logdev, shift_age, shift_size)
-      @log.progname = @appname
-      @log.level = @level
-    end
-
-    def log=(logdev)
-      set_log(logdev)
-    end
-
-    #
-    # Set the logging threshold, just like <tt>Logger#level=</tt>.
-    #
-    def level=(level)
-      @level = level
-      @log.level = @level
-    end
-
-    #
-    # See Logger#add.  This application's +appname+ is used.
-    #
-    def log(severity, message = nil, &block)
-      @log.add(severity, message, @appname, &block) if @log
-    end
-
-  private
-
-    def run
-      # TODO: should be an NotImplementedError
-      raise RuntimeError.new('Method run must be defined in the derived class.')
-    end
-  end
-end
diff --git a/lib/mathn.rb b/lib/mathn.rb
deleted file mode 100644
index aae4620c3f..0000000000
--- a/lib/mathn.rb
+++ /dev/null
@@ -1,324 +0,0 @@
-#--
-# $Release Version: 0.5 $
-# $Revision: 1.1.1.1.4.1 $
-
-##
-# = mathn
-#
-# mathn is a library for changing the way Ruby does math.  If you need
-# more precise rounding with multiple division or exponentiation
-# operations, then mathn is the right tool.
-#
-# Without mathn:
-#
-#   3 / 2 => 1 # Integer
-#
-# With mathn:
-#
-#   3 / 2 => 3/2 # Rational
-#
-# mathn features late rounding and lacks truncation of intermediate results:
-#
-# Without mathn:
-#
-#   20 / 9 * 3 * 14 / 7 * 3 / 2 # => 18
-#
-# With mathn:
-#
-#   20 / 9 * 3 * 14 / 7 * 3 / 2 # => 20
-#
-#
-# When you require 'mathn', the libraries for Prime, CMath, Matrix and Vector
-# are also loaded.
-#
-# == Copyright
-#
-# Author: Keiju ISHITSUKA (SHL Japan Inc.)
-#--
-# class Numeric follows to make this documentation findable in a reasonable
-# location
-
-class Numeric; end
-
-require "cmath.rb"
-require "matrix.rb"
-require "prime.rb"
-
-require "mathn/rational"
-require "mathn/complex"
-
-unless defined?(Math.exp!)
-  Object.instance_eval{remove_const :Math}
-  Math = CMath # :nodoc:
-end
-
-##
-# When mathn is required, Fixnum's division and exponentiation are enhanced to
-# return more precise values from mathematical expressions.
-#
-#   2/3*3  # => 0
-#   require 'mathn'
-#   2/3*3  # => 2
-
-class Fixnum
-  remove_method :/
-
-  ##
-  # +/+ defines the Rational division for Fixnum.
-  #
-  #   1/3  # => (1/3)
-
-  alias / quo
-
-  alias power! ** unless method_defined? :power!
-
-  ##
-  # Exponentiate by +other+
-
-  def ** (other)
-    if self < 0 && other.round != other
-      Complex(self, 0.0) ** other
-    else
-      power!(other)
-    end
-  end
-
-end
-
-##
-# When mathn is required Bignum's division and exponentiation are enhanced to
-# return more precise values from mathematical expressions.
-
-class Bignum
-  remove_method :/
-
-  ##
-  # +/+ defines the Rational division for Bignum.
-  #
-  #   (2**72) / ((2**70) * 3)  # => 4/3
-
-  alias / quo
-
-  alias power! ** unless method_defined? :power!
-
-  ##
-  # Exponentiate by +other+
-
-  def ** (other)
-    if self < 0 && other.round != other
-      Complex(self, 0.0) ** other
-    else
-      power!(other)
-    end
-  end
-
-end
-
-##
-# When mathn is required Rational is changed to simplify the use of Rational
-# operations.
-#
-# Normal behaviour:
-#
-#   Rational.new!(1,3) ** 2 # => Rational(1, 9)
-#   (1 / 3) ** 2            # => 0
-#
-# require 'mathn' behaviour:
-#
-#   (1 / 3) ** 2            # => 1/9
-
-class Rational
-  remove_method :**
-
-  ##
-  # Exponentiate by +other+
-  #
-  #   (1/3) ** 2 # => 1/9
-
-  def ** (other)
-    if other.kind_of?(Rational)
-      other2 = other
-      if self < 0
-        return Complex(self, 0.0) ** other
-      elsif other == 0
-        return Rational(1,1)
-      elsif self == 0
-        return Rational(0,1)
-      elsif self == 1
-        return Rational(1,1)
-      end
-
-      npd = numerator.prime_division
-      dpd = denominator.prime_division
-      if other < 0
-        other = -other
-        npd, dpd = dpd, npd
-      end
-
-      for elm in npd
-        elm[1] = elm[1] * other
-        if !elm[1].kind_of?(Integer) and elm[1].denominator != 1
-          return Float(self) ** other2
-        end
-        elm[1] = elm[1].to_i
-      end
-
-      for elm in dpd
-        elm[1] = elm[1] * other
-        if !elm[1].kind_of?(Integer) and elm[1].denominator != 1
-          return Float(self) ** other2
-        end
-        elm[1] = elm[1].to_i
-      end
-
-      num = Integer.from_prime_division(npd)
-      den = Integer.from_prime_division(dpd)
-
-      Rational(num,den)
-
-    elsif other.kind_of?(Integer)
-      if other > 0
-        num = numerator ** other
-        den = denominator ** other
-      elsif other < 0
-        num = denominator ** -other
-        den = numerator ** -other
-      elsif other == 0
-        num = 1
-        den = 1
-      end
-      Rational(num, den)
-    elsif other.kind_of?(Float)
-      Float(self) ** other
-    else
-      x , y = other.coerce(self)
-      x ** y
-    end
-  end
-end
-
-##
-# When mathn is required, the Math module changes as follows:
-#
-# Standard Math module behaviour:
-#   Math.sqrt(4/9)     # => 0.0
-#   Math.sqrt(4.0/9.0) # => 0.666666666666667
-#   Math.sqrt(- 4/9)   # => Errno::EDOM: Numerical argument out of domain - sqrt
-#
-# After require 'mathn', this is changed to:
-#
-#   require 'mathn'
-#   Math.sqrt(4/9)      # => 2/3
-#   Math.sqrt(4.0/9.0)  # => 0.666666666666667
-#   Math.sqrt(- 4/9)    # => Complex(0, 2/3)
-
-module Math
-  remove_method(:sqrt)
-
-  ##
-  # Computes the square root of +a+.  It makes use of Complex and
-  # Rational to have no rounding errors if possible.
-  #
-  #   Math.sqrt(4/9)      # => 2/3
-  #   Math.sqrt(- 4/9)    # => Complex(0, 2/3)
-  #   Math.sqrt(4.0/9.0)  # => 0.666666666666667
-
-  def sqrt(a)
-    if a.kind_of?(Complex)
-      abs = sqrt(a.real*a.real + a.imag*a.imag)
-#      if not abs.kind_of?(Rational)
-#        return a**Rational(1,2)
-#      end
-      x = sqrt((a.real + abs)/Rational(2))
-      y = sqrt((-a.real + abs)/Rational(2))
-#      if !(x.kind_of?(Rational) and y.kind_of?(Rational))
-#        return a**Rational(1,2)
-#      end
-      if a.imag >= 0
-        Complex(x, y)
-      else
-        Complex(x, -y)
-      end
-    elsif a.respond_to?(:nan?) and a.nan?
-      a
-    elsif a >= 0
-      rsqrt(a)
-    else
-      Complex(0,rsqrt(-a))
-    end
-  end
-
-  ##
-  # Compute square root of a non negative number. This method is
-  # internally used by +Math.sqrt+.
-
-  def rsqrt(a)
-    if a.kind_of?(Float)
-      sqrt!(a)
-    elsif a.kind_of?(Rational)
-      rsqrt(a.numerator)/rsqrt(a.denominator)
-    else
-      src = a
-      max = 2 ** 32
-      byte_a = [src & 0xffffffff]
-      # ruby's bug
-      while (src >= max) and (src >>= 32)
-        byte_a.unshift src & 0xffffffff
-      end
-
-      answer = 0
-      main = 0
-      side = 0
-      for elm in byte_a
-        main = (main << 32) + elm
-        side <<= 16
-        if answer != 0
-          if main * 4  < side * side
-            applo = main.div(side)
-          else
-            applo = ((sqrt!(side * side + 4 * main) - side)/2.0).to_i + 1
-          end
-        else
-          applo = sqrt!(main).to_i + 1
-        end
-
-        while (x = (side + applo) * applo) > main
-          applo -= 1
-        end
-        main -= x
-        answer = (answer << 16) + applo
-        side += applo * 2
-      end
-      if main == 0
-        answer
-      else
-        sqrt!(a)
-      end
-    end
-  end
-
-  class << self
-    remove_method(:sqrt)
-  end
-  module_function :sqrt
-  module_function :rsqrt
-end
-
-##
-# When mathn is required, Float is changed to handle Complex numbers.
-
-class Float
-  alias power! **
-
-  ##
-  # Exponentiate by +other+
-
-  def ** (other)
-    if self < 0 && other.round != other
-      Complex(self, 0.0) ** other
-    else
-      power!(other)
-    end
-  end
-
-end
diff --git a/lib/matrix.rb b/lib/matrix.rb
deleted file mode 100644
index 3c078c0c06..0000000000
--- a/lib/matrix.rb
+++ /dev/null
@@ -1,1866 +0,0 @@
-# encoding: utf-8
-#
-# = matrix.rb
-#
-# An implementation of Matrix and Vector classes.
-#
-# See classes Matrix and Vector for documentation.
-#
-# Current Maintainer:: Marc-André Lafortune
-# Original Author:: Keiju ISHITSUKA
-# Original Documentation:: Gavin Sinclair (sourced from <i>Ruby in a Nutshell</i> (Matsumoto, O'Reilly))
-##
-
-require "e2mmap.rb"
-
-module ExceptionForMatrix # :nodoc:
-  extend Exception2MessageMapper
-  def_e2message(TypeError, "wrong argument type %s (expected %s)")
-  def_e2message(ArgumentError, "Wrong # of arguments(%d for %d)")
-
-  def_exception("ErrDimensionMismatch", "\#{self.name} dimension mismatch")
-  def_exception("ErrNotRegular", "Not Regular Matrix")
-  def_exception("ErrOperationNotDefined", "Operation(%s) can\\'t be defined: %s op %s")
-  def_exception("ErrOperationNotImplemented", "Sorry, Operation(%s) not implemented: %s op %s")
-end
-
-#
-# The +Matrix+ class represents a mathematical matrix. It provides methods for creating
-# matrices, operating on them arithmetically and algebraically,
-# and determining their mathematical properties (trace, rank, inverse, determinant).
-#
-# == Method Catalogue
-#
-# To create a matrix:
-# * <tt> Matrix[*rows]                  </tt>
-# * <tt> Matrix.[](*rows)               </tt>
-# * <tt> Matrix.rows(rows, copy = true) </tt>
-# * <tt> Matrix.columns(columns)        </tt>
-# * <tt> Matrix.build(row_size, column_size, &block) </tt>
-# * <tt> Matrix.diagonal(*values)       </tt>
-# * <tt> Matrix.scalar(n, value)        </tt>
-# * <tt> Matrix.identity(n)             </tt>
-# * <tt> Matrix.unit(n)                 </tt>
-# * <tt> Matrix.I(n)                    </tt>
-# * <tt> Matrix.zero(n)                 </tt>
-# * <tt> Matrix.row_vector(row)         </tt>
-# * <tt> Matrix.column_vector(column)   </tt>
-#
-# To access Matrix elements/columns/rows/submatrices/properties:
-# * <tt>  [](i, j)                      </tt>
-# * <tt> #row_size                      </tt>
-# * <tt> #column_size                   </tt>
-# * <tt> #row(i)                        </tt>
-# * <tt> #column(j)                     </tt>
-# * <tt> #collect                       </tt>
-# * <tt> #map                           </tt>
-# * <tt> #each                          </tt>
-# * <tt> #each_with_index               </tt>
-# * <tt> #find_index                    </tt>
-# * <tt> #minor(*param)                 </tt>
-#
-# Properties of a matrix:
-# * <tt> #diagonal?                     </tt>
-# * <tt> #empty?                        </tt>
-# * <tt> #hermitian?                    </tt>
-# * <tt> #lower_triangular?             </tt>
-# * <tt> #normal?                       </tt>
-# * <tt> #orthogonal?                   </tt>
-# * <tt> #permutation?                  </tt>
-# * <tt> #real?                         </tt>
-# * <tt> #regular?                      </tt>
-# * <tt> #singular?                     </tt>
-# * <tt> #square?                       </tt>
-# * <tt> #symmetric?                    </tt>
-# * <tt> #unitary?                      </tt>
-# * <tt> #upper_triangular?             </tt>
-# * <tt> #zero?                         </tt>
-#
-# Matrix arithmetic:
-# * <tt>  *(m)                          </tt>
-# * <tt>  +(m)                          </tt>
-# * <tt>  -(m)                          </tt>
-# * <tt> #/(m)                          </tt>
-# * <tt> #inverse                       </tt>
-# * <tt> #inv                           </tt>
-# * <tt>  **                            </tt>
-#
-# Matrix functions:
-# * <tt> #determinant                   </tt>
-# * <tt> #det                           </tt>
-# * <tt> #rank                          </tt>
-# * <tt> #round                         </tt>
-# * <tt> #trace                         </tt>
-# * <tt> #tr                            </tt>
-# * <tt> #transpose                     </tt>
-# * <tt> #t                             </tt>
-#
-# Matrix decompositions:
-# * <tt> #eigen                         </tt>
-# * <tt> #eigensystem                   </tt>
-# * <tt> #lup                           </tt>
-# * <tt> #lup_decomposition             </tt>
-#
-# Complex arithmetic:
-# * <tt> conj                           </tt>
-# * <tt> conjugate                      </tt>
-# * <tt> imag                           </tt>
-# * <tt> imaginary                      </tt>
-# * <tt> real                           </tt>
-# * <tt> rect                           </tt>
-# * <tt> rectangular                    </tt>
-#
-# Conversion to other data types:
-# * <tt> #coerce(other)                 </tt>
-# * <tt> #row_vectors                   </tt>
-# * <tt> #column_vectors                </tt>
-# * <tt> #to_a                          </tt>
-#
-# String representations:
-# * <tt> #to_s                          </tt>
-# * <tt> #inspect                       </tt>
-#
-class Matrix
-  include Enumerable
-  include ExceptionForMatrix
-  autoload :EigenvalueDecomposition, "matrix/eigenvalue_decomposition"
-  autoload :LUPDecomposition, "matrix/lup_decomposition"
-
-  # instance creations
-  private_class_method :new
-  attr_reader :rows
-  protected :rows
-
-  #
-  # Creates a matrix where each argument is a row.
-  #   Matrix[ [25, 93], [-1, 66] ]
-  #      =>  25 93
-  #          -1 66
-  #
-  def Matrix.[](*rows)
-    Matrix.rows(rows, false)
-  end
-
-  #
-  # Creates a matrix where +rows+ is an array of arrays, each of which is a row
-  # of the matrix.  If the optional argument +copy+ is false, use the given
-  # arrays as the internal structure of the matrix without copying.
-  #   Matrix.rows([[25, 93], [-1, 66]])
-  #      =>  25 93
-  #          -1 66
-  #
-  def Matrix.rows(rows, copy = true)
-    rows = convert_to_array(rows)
-    rows.map! do |row|
-      convert_to_array(row, copy)
-    end
-    size = (rows[0] || []).size
-    rows.each do |row|
-      Matrix.Raise ErrDimensionMismatch, "row size differs (#{row.size} should be #{size})" unless row.size == size
-    end
-    new rows, size
-  end
-
-  #
-  # Creates a matrix using +columns+ as an array of column vectors.
-  #   Matrix.columns([[25, 93], [-1, 66]])
-  #      =>  25 -1
-  #          93 66
-  #
-  def Matrix.columns(columns)
-    Matrix.rows(columns, false).transpose
-  end
-
-  #
-  # Creates a matrix of size +row_size+ x +column_size+.
-  # It fills the values by calling the given block,
-  # passing the current row and column.
-  # Returns an enumerator if no block is given.
-  #
-  #   m = Matrix.build(2, 4) {|row, col| col - row }
-  #     => Matrix[[0, 1, 2, 3], [-1, 0, 1, 2]]
-  #   m = Matrix.build(3) { rand }
-  #     => a 3x3 matrix with random elements
-  #
-  def Matrix.build(row_size, column_size = row_size)
-    row_size = CoercionHelper.coerce_to_int(row_size)
-    column_size = CoercionHelper.coerce_to_int(column_size)
-    raise ArgumentError if row_size < 0 || column_size < 0
-    return to_enum :build, row_size, column_size unless block_given?
-    rows = Array.new(row_size) do |i|
-      Array.new(column_size) do |j|
-        yield i, j
-      end
-    end
-    new rows, column_size
-  end
-
-  #
-  # Creates a matrix where the diagonal elements are composed of +values+.
-  #   Matrix.diagonal(9, 5, -3)
-  #     =>  9  0  0
-  #         0  5  0
-  #         0  0 -3
-  #
-  def Matrix.diagonal(*values)
-    size = values.size
-    rows = Array.new(size) {|j|
-      row = Array.new(size, 0)
-      row[j] = values[j]
-      row
-    }
-    new rows
-  end
-
-  #
-  # Creates an +n+ by +n+ diagonal matrix where each diagonal element is
-  # +value+.
-  #   Matrix.scalar(2, 5)
-  #     => 5 0
-  #        0 5
-  #
-  def Matrix.scalar(n, value)
-    Matrix.diagonal(*Array.new(n, value))
-  end
-
-  #
-  # Creates an +n+ by +n+ identity matrix.
-  #   Matrix.identity(2)
-  #     => 1 0
-  #        0 1
-  #
-  def Matrix.identity(n)
-    Matrix.scalar(n, 1)
-  end
-  class << Matrix
-    alias unit identity
-    alias I identity
-  end
-
-  #
-  # Creates a zero matrix.
-  #   Matrix.zero(2)
-  #     => 0 0
-  #        0 0
-  #
-  def Matrix.zero(row_size, column_size = row_size)
-    rows = Array.new(row_size){Array.new(column_size, 0)}
-    new rows, column_size
-  end
-
-  #
-  # Creates a single-row matrix where the values of that row are as given in
-  # +row+.
-  #   Matrix.row_vector([4,5,6])
-  #     => 4 5 6
-  #
-  def Matrix.row_vector(row)
-    row = convert_to_array(row)
-    new [row]
-  end
-
-  #
-  # Creates a single-column matrix where the values of that column are as given
-  # in +column+.
-  #   Matrix.column_vector([4,5,6])
-  #     => 4
-  #        5
-  #        6
-  #
-  def Matrix.column_vector(column)
-    column = convert_to_array(column)
-    new [column].transpose, 1
-  end
-
-  #
-  # Creates a empty matrix of +row_size+ x +column_size+.
-  # At least one of +row_size+ or +column_size+ must be 0.
-  #
-  #   m = Matrix.empty(2, 0)
-  #   m == Matrix[ [], [] ]
-  #     => true
-  #   n = Matrix.empty(0, 3)
-  #   n == Matrix.columns([ [], [], [] ])
-  #     => true
-  #   m * n
-  #     => Matrix[[0, 0, 0], [0, 0, 0]]
-  #
-  def Matrix.empty(row_size = 0, column_size = 0)
-    Matrix.Raise ArgumentError, "One size must be 0" if column_size != 0 && row_size != 0
-    Matrix.Raise ArgumentError, "Negative size" if column_size < 0 || row_size < 0
-
-    new([[]]*row_size, column_size)
-  end
-
-  #
-  # Matrix.new is private; use Matrix.rows, columns, [], etc... to create.
-  #
-  def initialize(rows, column_size = rows[0].size)
-    # No checking is done at this point. rows must be an Array of Arrays.
-    # column_size must be the size of the first row, if there is one,
-    # otherwise it *must* be specified and can be any integer >= 0
-    @rows = rows
-    @column_size = column_size
-  end
-
-  def new_matrix(rows, column_size = rows[0].size) # :nodoc:
-    Matrix.send(:new, rows, column_size) # bypass privacy of Matrix.new
-  end
-  private :new_matrix
-
-  #
-  # Returns element (+i+,+j+) of the matrix.  That is: row +i+, column +j+.
-  #
-  def [](i, j)
-    @rows.fetch(i){return nil}[j]
-  end
-  alias element []
-  alias component []
-
-  def []=(i, j, v)
-    @rows[i][j] = v
-  end
-  alias set_element []=
-  alias set_component []=
-  private :[]=, :set_element, :set_component
-
-  #
-  # Returns the number of rows.
-  #
-  def row_size
-    @rows.size
-  end
-
-  #
-  # Returns the number of columns.
-  #
-  attr_reader :column_size
-
-  #
-  # Returns row vector number +i+ of the matrix as a Vector (starting at 0 like
-  # an array).  When a block is given, the elements of that vector are iterated.
-  #
-  def row(i, &block) # :yield: e
-    if block_given?
-      @rows.fetch(i){return self}.each(&block)
-      self
-    else
-      Vector.elements(@rows.fetch(i){return nil})
-    end
-  end
-
-  #
-  # Returns column vector number +j+ of the matrix as a Vector (starting at 0
-  # like an array).  When a block is given, the elements of that vector are
-  # iterated.
-  #
-  def column(j) # :yield: e
-    if block_given?
-      return self if j >= column_size || j < -column_size
-      row_size.times do |i|
-        yield @rows[i][j]
-      end
-      self
-    else
-      return nil if j >= column_size || j < -column_size
-      col = Array.new(row_size) {|i|
-        @rows[i][j]
-      }
-      Vector.elements(col, false)
-    end
-  end
-
-  #
-  # Returns a matrix that is the result of iteration of the given block over all
-  # elements of the matrix.
-  #   Matrix[ [1,2], [3,4] ].collect { |e| e**2 }
-  #     => 1  4
-  #        9 16
-  #
-  def collect(&block) # :yield: e
-    return to_enum(:collect) unless block_given?
-    rows = @rows.collect{|row| row.collect(&block)}
-    new_matrix rows, column_size
-  end
-  alias map collect
-
-  #
-  # Yields all elements of the matrix, starting with those of the first row,
-  # or returns an Enumerator is no block given.
-  # Elements can be restricted by passing an argument:
-  # * :all (default): yields all elements
-  # * :diagonal: yields only elements on the diagonal
-  # * :off_diagonal: yields all elements except on the diagonal
-  # * :lower: yields only elements on or below the diagonal
-  # * :strict_lower: yields only elements below the diagonal
-  # * :strict_upper: yields only elements above the diagonal
-  # * :upper: yields only elements on or above the diagonal
-  #
-  #   Matrix[ [1,2], [3,4] ].each { |e| puts e }
-  #     # => prints the numbers 1 to 4
-  #   Matrix[ [1,2], [3,4] ].each(:strict_lower).to_a # => [3]
-  #
-  def each(which = :all) # :yield: e
-    return to_enum :each, which unless block_given?
-    last = column_size - 1
-    case which
-    when :all
-      block = Proc.new
-      @rows.each do |row|
-        row.each(&block)
-      end
-    when :diagonal
-      @rows.each_with_index do |row, row_index|
-        yield row.fetch(row_index){return self}
-      end
-    when :off_diagonal
-      @rows.each_with_index do |row, row_index|
-        column_size.times do |col_index|
-          yield row[col_index] unless row_index == col_index
-        end
-      end
-    when :lower
-      @rows.each_with_index do |row, row_index|
-        0.upto([row_index, last].min) do |col_index|
-          yield row[col_index]
-        end
-      end
-    when :strict_lower
-      @rows.each_with_index do |row, row_index|
-        [row_index, column_size].min.times do |col_index|
-          yield row[col_index]
-        end
-      end
-    when :strict_upper
-      @rows.each_with_index do |row, row_index|
-        (row_index+1).upto(last) do |col_index|
-          yield row[col_index]
-        end
-      end
-    when :upper
-      @rows.each_with_index do |row, row_index|
-        row_index.upto(last) do |col_index|
-          yield row[col_index]
-        end
-      end
-    else
-      Matrix.Raise ArgumentError, "expected #{which.inspect} to be one of :all, :diagonal, :off_diagonal, :lower, :strict_lower, :strict_upper or :upper"
-    end
-    self
-  end
-
-  #
-  # Same as #each, but the row index and column index in addition to the element
-  #
-  #   Matrix[ [1,2], [3,4] ].each_with_index do |e, row, col|
-  #     puts "#{e} at #{row}, #{col}"
-  #   end
-  #     # => Prints:
-  #     #    1 at 0, 0
-  #     #    2 at 0, 1
-  #     #    3 at 1, 0
-  #     #    4 at 1, 1
-  #
-  def each_with_index(which = :all) # :yield: e, row, column
-    return to_enum :each_with_index, which unless block_given?
-    last = column_size - 1
-    case which
-    when :all
-      @rows.each_with_index do |row, row_index|
-        row.each_with_index do |e, col_index|
-          yield e, row_index, col_index
-        end
-      end
-    when :diagonal
-      @rows.each_with_index do |row, row_index|
-        yield row.fetch(row_index){return self}, row_index, row_index
-      end
-    when :off_diagonal
-      @rows.each_with_index do |row, row_index|
-        column_size.times do |col_index|
-          yield row[col_index], row_index, col_index unless row_index == col_index
-        end
-      end
-    when :lower
-      @rows.each_with_index do |row, row_index|
-        0.upto([row_index, last].min) do |col_index|
-          yield row[col_index], row_index, col_index
-        end
-      end
-    when :strict_lower
-      @rows.each_with_index do |row, row_index|
-        [row_index, column_size].min.times do |col_index|
-          yield row[col_index], row_index, col_index
-        end
-      end
-    when :strict_upper
-      @rows.each_with_index do |row, row_index|
-        (row_index+1).upto(last) do |col_index|
-          yield row[col_index], row_index, col_index
-        end
-      end
-    when :upper
-      @rows.each_with_index do |row, row_index|
-        row_index.upto(last) do |col_index|
-          yield row[col_index], row_index, col_index
-        end
-      end
-    else
-      Matrix.Raise ArgumentError, "expected #{which.inspect} to be one of :all, :diagonal, :off_diagonal, :lower, :strict_lower, :strict_upper or :upper"
-    end
-    self
-  end
-
-  SELECTORS = {all: true, diagonal: true, off_diagonal: true, lower: true, strict_lower: true, strict_upper: true, upper: true}.freeze
-  #
-  # :call-seq:
-  #   index(value, selector = :all) -> [row, column]
-  #   index(selector = :all){ block } -> [row, column]
-  #   index(selector = :all) -> an_enumerator
-  #
-  # The index method is specialized to return the index as [row, column]
-  # It also accepts an optional +selector+ argument, see #each for details.
-  #
-  #   Matrix[ [1,2], [3,4] ].index(&:even?) # => [0, 1]
-  #   Matrix[ [1,1], [1,1] ].index(1, :strict_lower) # => [1, 0]
-  #
-  def index(*args)
-    raise ArgumentError, "wrong number of arguments(#{args.size} for 0-2)" if args.size > 2
-    which = (args.size == 2 || SELECTORS.include?(args.last)) ? args.pop : :all
-    return to_enum :find_index, which, *args unless block_given? || args.size == 1
-    if args.size == 1
-      value = args.first
-      each_with_index(which) do |e, row_index, col_index|
-        return row_index, col_index if e == value
-      end
-    else
-      each_with_index(which) do |e, row_index, col_index|
-        return row_index, col_index if yield e
-      end
-    end
-    nil
-  end
-  alias_method :find_index, :index
-  #
-  # Returns a section of the matrix.  The parameters are either:
-  # *  start_row, nrows, start_col, ncols; OR
-  # *  row_range, col_range
-  #
-  #   Matrix.diagonal(9, 5, -3).minor(0..1, 0..2)
-  #     => 9 0 0
-  #        0 5 0
-  #
-  # Like Array#[], negative indices count backward from the end of the
-  # row or column (-1 is the last element). Returns nil if the starting
-  # row or column is greater than row_size or column_size respectively.
-  #
-  def minor(*param)
-    case param.size
-    when 2
-      row_range, col_range = param
-      from_row = row_range.first
-      from_row += row_size if from_row < 0
-      to_row = row_range.end
-      to_row += row_size if to_row < 0
-      to_row += 1 unless row_range.exclude_end?
-      size_row = to_row - from_row
-
-      from_col = col_range.first
-      from_col += column_size if from_col < 0
-      to_col = col_range.end
-      to_col += column_size if to_col < 0
-      to_col += 1 unless col_range.exclude_end?
-      size_col = to_col - from_col
-    when 4
-      from_row, size_row, from_col, size_col = param
-      return nil if size_row < 0 || size_col < 0
-      from_row += row_size if from_row < 0
-      from_col += column_size if from_col < 0
-    else
-      Matrix.Raise ArgumentError, param.inspect
-    end
-
-    return nil if from_row > row_size || from_col > column_size || from_row < 0 || from_col < 0
-    rows = @rows[from_row, size_row].collect{|row|
-      row[from_col, size_col]
-    }
-    new_matrix rows, [column_size - from_col, size_col].min
-  end
-
-  #--
-  # TESTING -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
-  #++
-
-  #
-  # Returns +true+ is this is a diagonal matrix.
-  # Raises an error if matrix is not square.
-  #
-  def diagonal?
-    Matrix.Raise ErrDimensionMismatch unless square?
-    each(:off_diagonal).all?(&:zero?)
-  end
-
-  #
-  # Returns +true+ if this is an empty matrix, i.e. if the number of rows
-  # or the number of columns is 0.
-  #
-  def empty?
-    column_size == 0 || row_size == 0
-  end
-
-  #
-  # Returns +true+ is this is an hermitian matrix.
-  # Raises an error if matrix is not square.
-  #
-  def hermitian?
-    Matrix.Raise ErrDimensionMismatch unless square?
-    each_with_index(:strict_upper).all? do |e, row, col|
-      e == rows[col][row].conj
-    end
-  end
-
-  #
-  # Returns +true+ is this is a lower triangular matrix.
-  #
-  def lower_triangular?
-    each(:strict_upper).all?(&:zero?)
-  end
-
-  #
-  # Returns +true+ is this is a normal matrix.
-  # Raises an error if matrix is not square.
-  #
-  def normal?
-    Matrix.Raise ErrDimensionMismatch unless square?
-    rows.each_with_index do |row_i, i|
-      rows.each_with_index do |row_j, j|
-        s = 0
-        rows.each_with_index do |row_k, k|
-          s += row_i[k] * row_j[k].conj - row_k[i].conj * row_k[j]
-        end
-        return false unless s == 0
-      end
-    end
-    true
-  end
-
-  #
-  # Returns +true+ is this is an orthogonal matrix
-  # Raises an error if matrix is not square.
-  #
-  def orthogonal?
-    Matrix.Raise ErrDimensionMismatch unless square?
-    rows.each_with_index do |row, i|
-      column_size.times do |j|
-        s = 0
-        row_size.times do |k|
-          s += row[k] * rows[k][j]
-        end
-        return false unless s == (i == j ? 1 : 0)
-      end
-    end
-    true
-  end
-
-  #
-  # Returns +true+ is this is a permutation matrix
-  # Raises an error if matrix is not square.
-  #
-  def permutation?
-    Matrix.Raise ErrDimensionMismatch unless square?
-    cols = Array.new(column_size)
-    rows.each_with_index do |row, i|
-      found = false
-      row.each_with_index do |e, j|
-        if e == 1
-          return false if found || cols[j]
-          found = cols[j] = true
-        elsif e != 0
-          return false
-        end
-      end
-      return false unless found
-    end
-    true
-  end
-
-  #
-  # Returns +true+ if all entries of the matrix are real.
-  #
-  def real?
-    all?(&:real?)
-  end
-
-  #
-  # Returns +true+ if this is a regular (i.e. non-singular) matrix.
-  #
-  def regular?
-    not singular?
-  end
-
-  #
-  # Returns +true+ is this is a singular matrix.
-  #
-  def singular?
-    determinant == 0
-  end
-
-  #
-  # Returns +true+ is this is a square matrix.
-  #
-  def square?
-    column_size == row_size
-  end
-
-  #
-  # Returns +true+ is this is a symmetric matrix.
-  # Raises an error if matrix is not square.
-  #
-  def symmetric?
-    Matrix.Raise ErrDimensionMismatch unless square?
-    each_with_index(:strict_upper).all? do |e, row, col|
-      e == rows[col][row]
-    end
-  end
-
-  #
-  # Returns +true+ is this is a unitary matrix
-  # Raises an error if matrix is not square.
-  #
-  def unitary?
-    Matrix.Raise ErrDimensionMismatch unless square?
-    rows.each_with_index do |row, i|
-      column_size.times do |j|
-        s = 0
-        row_size.times do |k|
-          s += row[k].conj * rows[k][j]
-        end
-        return false unless s == (i == j ? 1 : 0)
-      end
-    end
-    true
-  end
-
-  #
-  # Returns +true+ is this is an upper triangular matrix.
-  #
-  def upper_triangular?
-    each(:strict_lower).all?(&:zero?)
-  end
-
-  #
-  # Returns +true+ is this is a matrix with only zero elements
-  #
-  def zero?
-    all?(&:zero?)
-  end
-
-  #--
-  # OBJECT METHODS -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
-  #++
-
-  #
-  # Returns +true+ if and only if the two matrices contain equal elements.
-  #
-  def ==(other)
-    return false unless Matrix === other &&
-                        column_size == other.column_size # necessary for empty matrices
-    rows == other.rows
-  end
-
-  def eql?(other)
-    return false unless Matrix === other &&
-                        column_size == other.column_size # necessary for empty matrices
-    rows.eql? other.rows
-  end
-
-  #
-  # Returns a clone of the matrix, so that the contents of each do not reference
-  # identical objects.
-  # There should be no good reason to do this since Matrices are immutable.
-  #
-  def clone
-    new_matrix @rows.map(&:dup), column_size
-  end
-
-  #
-  # Returns a hash-code for the matrix.
-  #
-  def hash
-    @rows.hash
-  end
-
-  #--
-  # ARITHMETIC -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
-  #++
-
-  #
-  # Matrix multiplication.
-  #   Matrix[[2,4], [6,8]] * Matrix.identity(2)
-  #     => 2 4
-  #        6 8
-  #
-  def *(m) # m is matrix or vector or number
-    case(m)
-    when Numeric
-      rows = @rows.collect {|row|
-        row.collect {|e| e * m }
-      }
-      return new_matrix rows, column_size
-    when Vector
-      m = Matrix.column_vector(m)
-      r = self * m
-      return r.column(0)
-    when Matrix
-      Matrix.Raise ErrDimensionMismatch if column_size != m.row_size
-
-      rows = Array.new(row_size) {|i|
-        Array.new(m.column_size) {|j|
-          (0 ... column_size).inject(0) do |vij, k|
-            vij + self[i, k] * m[k, j]
-          end
-        }
-      }
-      return new_matrix rows, m.column_size
-    else
-      return apply_through_coercion(m, __method__)
-    end
-  end
-
-  #
-  # Matrix addition.
-  #   Matrix.scalar(2,5) + Matrix[[1,0], [-4,7]]
-  #     =>  6  0
-  #        -4 12
-  #
-  def +(m)
-    case m
-    when Numeric
-      Matrix.Raise ErrOperationNotDefined, "+", self.class, m.class
-    when Vector
-      m = Matrix.column_vector(m)
-    when Matrix
-    else
-      return apply_through_coercion(m, __method__)
-    end
-
-    Matrix.Raise ErrDimensionMismatch unless row_size == m.row_size and column_size == m.column_size
-
-    rows = Array.new(row_size) {|i|
-      Array.new(column_size) {|j|
-        self[i, j] + m[i, j]
-      }
-    }
-    new_matrix rows, column_size
-  end
-
-  #
-  # Matrix subtraction.
-  #   Matrix[[1,5], [4,2]] - Matrix[[9,3], [-4,1]]
-  #     => -8  2
-  #         8  1
-  #
-  def -(m)
-    case m
-    when Numeric
-      Matrix.Raise ErrOperationNotDefined, "-", self.class, m.class
-    when Vector
-      m = Matrix.column_vector(m)
-    when Matrix
-    else
-      return apply_through_coercion(m, __method__)
-    end
-
-    Matrix.Raise ErrDimensionMismatch unless row_size == m.row_size and column_size == m.column_size
-
-    rows = Array.new(row_size) {|i|
-      Array.new(column_size) {|j|
-        self[i, j] - m[i, j]
-      }
-    }
-    new_matrix rows, column_size
-  end
-
-  #
-  # Matrix division (multiplication by the inverse).
-  #   Matrix[[7,6], [3,9]] / Matrix[[2,9], [3,1]]
-  #     => -7  1
-  #        -3 -6
-  #
-  def /(other)
-    case other
-    when Numeric
-      rows = @rows.collect {|row|
-        row.collect {|e| e / other }
-      }
-      return new_matrix rows, column_size
-    when Matrix
-      return self * other.inverse
-    else
-      return apply_through_coercion(other, __method__)
-    end
-  end
-
-  #
-  # Returns the inverse of the matrix.
-  #   Matrix[[-1, -1], [0, -1]].inverse
-  #     => -1  1
-  #         0 -1
-  #
-  def inverse
-    Matrix.Raise ErrDimensionMismatch unless square?
-    Matrix.I(row_size).send(:inverse_from, self)
-  end
-  alias inv inverse
-
-  def inverse_from(src) # :nodoc:
-    last = row_size - 1
-    a = src.to_a
-
-    0.upto(last) do |k|
-      i = k
-      akk = a[k][k].abs
-      (k+1).upto(last) do |j|
-        v = a[j][k].abs
-        if v > akk
-          i = j
-          akk = v
-        end
-      end
-      Matrix.Raise ErrNotRegular if akk == 0
-      if i != k
-        a[i], a[k] = a[k], a[i]
-        @rows[i], @rows[k] = @rows[k], @rows[i]
-      end
-      akk = a[k][k]
-
-      0.upto(last) do |ii|
-        next if ii == k
-        q = a[ii][k].quo(akk)
-        a[ii][k] = 0
-
-        (k + 1).upto(last) do |j|
-          a[ii][j] -= a[k][j] * q
-        end
-        0.upto(last) do |j|
-          @rows[ii][j] -= @rows[k][j] * q
-        end
-      end
-
-      (k+1).upto(last) do |j|
-        a[k][j] = a[k][j].quo(akk)
-      end
-      0.upto(last) do |j|
-        @rows[k][j] = @rows[k][j].quo(akk)
-      end
-    end
-    self
-  end
-  private :inverse_from
-
-  #
-  # Matrix exponentiation.
-  # Equivalent to multiplying the matrix by itself N times.
-  # Non integer exponents will be handled by diagonalizing the matrix.
-  #
-  #   Matrix[[7,6], [3,9]] ** 2
-  #     => 67 96
-  #        48 99
-  #
-  def ** (other)
-    case other
-    when Integer
-      x = self
-      if other <= 0
-        x = self.inverse
-        return Matrix.identity(self.column_size) if other == 0
-        other = -other
-      end
-      z = nil
-      loop do
-        z = z ? z * x : x if other[0] == 1
-        return z if (other >>= 1).zero?
-        x *= x
-      end
-    when Numeric
-      v, d, v_inv = eigensystem
-      v * Matrix.diagonal(*d.each(:diagonal).map{|e| e ** other}) * v_inv
-    else
-      Matrix.Raise ErrOperationNotDefined, "**", self.class, other.class
-    end
-  end
-
-  #--
-  # MATRIX FUNCTIONS -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
-  #++
-
-  #
-  # Returns the determinant of the matrix.
-  #
-  # Beware that using Float values can yield erroneous results
-  # because of their lack of precision.
-  # Consider using exact types like Rational or BigDecimal instead.
-  #
-  #   Matrix[[7,6], [3,9]].determinant
-  #     => 45
-  #
-  def determinant
-    Matrix.Raise ErrDimensionMismatch unless square?
-    m = @rows
-    case row_size
-      # Up to 4x4, give result using Laplacian expansion by minors.
-      # This will typically be faster, as well as giving good results
-      # in case of Floats
-    when 0
-      +1
-    when 1
-      + m[0][0]
-    when 2
-      + m[0][0] * m[1][1] - m[0][1] * m[1][0]
-    when 3
-      m0, m1, m2 = m
-      + m0[0] * m1[1] * m2[2] - m0[0] * m1[2] * m2[1] \
-      - m0[1] * m1[0] * m2[2] + m0[1] * m1[2] * m2[0] \
-      + m0[2] * m1[0] * m2[1] - m0[2] * m1[1] * m2[0]
-    when 4
-      m0, m1, m2, m3 = m
-      + m0[0] * m1[1] * m2[2] * m3[3] - m0[0] * m1[1] * m2[3] * m3[2] \
-      - m0[0] * m1[2] * m2[1] * m3[3] + m0[0] * m1[2] * m2[3] * m3[1] \
-      + m0[0] * m1[3] * m2[1] * m3[2] - m0[0] * m1[3] * m2[2] * m3[1] \
-      - m0[1] * m1[0] * m2[2] * m3[3] + m0[1] * m1[0] * m2[3] * m3[2] \
-      + m0[1] * m1[2] * m2[0] * m3[3] - m0[1] * m1[2] * m2[3] * m3[0] \
-      - m0[1] * m1[3] * m2[0] * m3[2] + m0[1] * m1[3] * m2[2] * m3[0] \
-      + m0[2] * m1[0] * m2[1] * m3[3] - m0[2] * m1[0] * m2[3] * m3[1] \
-      - m0[2] * m1[1] * m2[0] * m3[3] + m0[2] * m1[1] * m2[3] * m3[0] \
-      + m0[2] * m1[3] * m2[0] * m3[1] - m0[2] * m1[3] * m2[1] * m3[0] \
-      - m0[3] * m1[0] * m2[1] * m3[2] + m0[3] * m1[0] * m2[2] * m3[1] \
-      + m0[3] * m1[1] * m2[0] * m3[2] - m0[3] * m1[1] * m2[2] * m3[0] \
-      - m0[3] * m1[2] * m2[0] * m3[1] + m0[3] * m1[2] * m2[1] * m3[0]
-    else
-      # For bigger matrices, use an efficient and general algorithm.
-      # Currently, we use the Gauss-Bareiss algorithm
-      determinant_bareiss
-    end
-  end
-  alias_method :det, :determinant
-
-  #
-  # Private. Use Matrix#determinant
-  #
-  # Returns the determinant of the matrix, using
-  # Bareiss' multistep integer-preserving gaussian elimination.
-  # It has the same computational cost order O(n^3) as standard Gaussian elimination.
-  # Intermediate results are fraction free and of lower complexity.
-  # A matrix of Integers will have thus intermediate results that are also Integers,
-  # with smaller bignums (if any), while a matrix of Float will usually have
-  # intermediate results with better precision.
-  #
-  def determinant_bareiss
-    size = row_size
-    last = size - 1
-    a = to_a
-    no_pivot = Proc.new{ return 0 }
-    sign = +1
-    pivot = 1
-    size.times do |k|
-      previous_pivot = pivot
-      if (pivot = a[k][k]) == 0
-        switch = (k+1 ... size).find(no_pivot) {|row|
-          a[row][k] != 0
-        }
-        a[switch], a[k] = a[k], a[switch]
-        pivot = a[k][k]
-        sign = -sign
-      end
-      (k+1).upto(last) do |i|
-        ai = a[i]
-        (k+1).upto(last) do |j|
-          ai[j] =  (pivot * ai[j] - ai[k] * a[k][j]) / previous_pivot
-        end
-      end
-    end
-    sign * pivot
-  end
-  private :determinant_bareiss
-
-  #
-  # deprecated; use Matrix#determinant
-  #
-  def determinant_e
-    warn "#{caller(1)[0]}: warning: Matrix#determinant_e is deprecated; use #determinant"
-    rank
-  end
-  alias det_e determinant_e
-
-  #
-  # Returns the rank of the matrix.
-  # Beware that using Float values can yield erroneous results
-  # because of their lack of precision.
-  # Consider using exact types like Rational or BigDecimal instead.
-  #
-  #   Matrix[[7,6], [3,9]].rank
-  #     => 2
-  #
-  def rank
-    # We currently use Bareiss' multistep integer-preserving gaussian elimination
-    # (see comments on determinant)
-    a = to_a
-    last_column = column_size - 1
-    last_row = row_size - 1
-    pivot_row = 0
-    previous_pivot = 1
-    0.upto(last_column) do |k|
-      switch_row = (pivot_row .. last_row).find {|row|
-        a[row][k] != 0
-      }
-      if switch_row
-        a[switch_row], a[pivot_row] = a[pivot_row], a[switch_row] unless pivot_row == switch_row
-        pivot = a[pivot_row][k]
-        (pivot_row+1).upto(last_row) do |i|
-           ai = a[i]
-           (k+1).upto(last_column) do |j|
-             ai[j] =  (pivot * ai[j] - ai[k] * a[pivot_row][j]) / previous_pivot
-           end
-         end
-        pivot_row += 1
-        previous_pivot = pivot
-      end
-    end
-    pivot_row
-  end
-
-  #
-  # deprecated; use Matrix#rank
-  #
-  def rank_e
-    warn "#{caller(1)[0]}: warning: Matrix#rank_e is deprecated; use #rank"
-    rank
-  end
-
-  # Returns a matrix with entries rounded to the given precision
-  # (see Float#round)
-  #
-  def round(ndigits=0)
-    map{|e| e.round(ndigits)}
-  end
-
-  #
-  # Returns the trace (sum of diagonal elements) of the matrix.
-  #   Matrix[[7,6], [3,9]].trace
-  #     => 16
-  #
-  def trace
-    Matrix.Raise ErrDimensionMismatch unless square?
-    (0...column_size).inject(0) do |tr, i|
-      tr + @rows[i][i]
-    end
-  end
-  alias tr trace
-
-  #
-  # Returns the transpose of the matrix.
-  #   Matrix[[1,2], [3,4], [5,6]]
-  #     => 1 2
-  #        3 4
-  #        5 6
-  #   Matrix[[1,2], [3,4], [5,6]].transpose
-  #     => 1 3 5
-  #        2 4 6
-  #
-  def transpose
-    return Matrix.empty(column_size, 0) if row_size.zero?
-    new_matrix @rows.transpose, row_size
-  end
-  alias t transpose
-
-  #--
-  # DECOMPOSITIONS -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
-  #++
-
-  #
-  # Returns the Eigensystem of the matrix; see +EigenvalueDecomposition+.
-  #   m = Matrix[[1, 2], [3, 4]]
-  #   v, d, v_inv = m.eigensystem
-  #   d.diagonal? # => true
-  #   v.inv == v_inv # => true
-  #   (v * d * v_inv).round(5) == m # => true
-  #
-  def eigensystem
-    EigenvalueDecomposition.new(self)
-  end
-  alias eigen eigensystem
-
-  #
-  # Returns the LUP decomposition of the matrix; see +LUPDecomposition+.
-  #   a = Matrix[[1, 2], [3, 4]]
-  #   l, u, p = a.lup
-  #   l.lower_triangular? # => true
-  #   u.upper_triangular? # => true
-  #   p.permutation?      # => true
-  #   l * u == a * p      # => true
-  #   a.lup.solve([2, 5]) # => Vector[(1/1), (1/2)]
-  #
-  def lup
-    LUPDecomposition.new(self)
-  end
-  alias lup_decomposition lup
-
-  #--
-  # COMPLEX ARITHMETIC -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
-  #++
-
-  #
-  # Returns the conjugate of the matrix.
-  #   Matrix[[Complex(1,2), Complex(0,1), 0], [1, 2, 3]]
-  #     => 1+2i   i  0
-  #           1   2  3
-  #   Matrix[[Complex(1,2), Complex(0,1), 0], [1, 2, 3]].conjugate
-  #     => 1-2i  -i  0
-  #           1   2  3
-  #
-  def conjugate
-    collect(&:conjugate)
-  end
-  alias conj conjugate
-
-  #
-  # Returns the imaginary part of the matrix.
-  #   Matrix[[Complex(1,2), Complex(0,1), 0], [1, 2, 3]]
-  #     => 1+2i  i  0
-  #           1  2  3
-  #   Matrix[[Complex(1,2), Complex(0,1), 0], [1, 2, 3]].imaginary
-  #     =>   2i  i  0
-  #           0  0  0
-  #
-  def imaginary
-    collect(&:imaginary)
-  end
-  alias imag imaginary
-
-  #
-  # Returns the real part of the matrix.
-  #   Matrix[[Complex(1,2), Complex(0,1), 0], [1, 2, 3]]
-  #     => 1+2i  i  0
-  #           1  2  3
-  #   Matrix[[Complex(1,2), Complex(0,1), 0], [1, 2, 3]].real
-  #     =>    1  0  0
-  #           1  2  3
-  #
-  def real
-    collect(&:real)
-  end
-
-  #
-  # Returns an array containing matrices corresponding to the real and imaginary
-  # parts of the matrix
-  #
-  # m.rect == [m.real, m.imag]  # ==> true for all matrices m
-  #
-  def rect
-    [real, imag]
-  end
-  alias rectangular rect
-
-  #--
-  # CONVERTING -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
-  #++
-
-  #
-  # The coerce method provides support for Ruby type coercion.
-  # This coercion mechanism is used by Ruby to handle mixed-type
-  # numeric operations: it is intended to find a compatible common
-  # type between the two operands of the operator.
-  # See also Numeric#coerce.
-  #
-  def coerce(other)
-    case other
-    when Numeric
-      return Scalar.new(other), self
-    else
-      raise TypeError, "#{self.class} can't be coerced into #{other.class}"
-    end
-  end
-
-  #
-  # Returns an array of the row vectors of the matrix.  See Vector.
-  #
-  def row_vectors
-    Array.new(row_size) {|i|
-      row(i)
-    }
-  end
-
-  #
-  # Returns an array of the column vectors of the matrix.  See Vector.
-  #
-  def column_vectors
-    Array.new(column_size) {|i|
-      column(i)
-    }
-  end
-
-  #
-  # Returns an array of arrays that describe the rows of the matrix.
-  #
-  def to_a
-    @rows.collect(&:dup)
-  end
-
-  def elements_to_f
-    warn "#{caller(1)[0]}: warning: Matrix#elements_to_f is deprecated, use map(&:to_f)"
-    map(&:to_f)
-  end
-
-  def elements_to_i
-    warn "#{caller(1)[0]}: warning: Matrix#elements_to_i is deprecated, use map(&:to_i)"
-    map(&:to_i)
-  end
-
-  def elements_to_r
-    warn "#{caller(1)[0]}: warning: Matrix#elements_to_r is deprecated, use map(&:to_r)"
-    map(&:to_r)
-  end
-
-  #--
-  # PRINTING -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
-  #++
-
-  #
-  # Overrides Object#to_s
-  #
-  def to_s
-    if empty?
-      "Matrix.empty(#{row_size}, #{column_size})"
-    else
-      "Matrix[" + @rows.collect{|row|
-        "[" + row.collect{|e| e.to_s}.join(", ") + "]"
-      }.join(", ")+"]"
-    end
-  end
-
-  #
-  # Overrides Object#inspect
-  #
-  def inspect
-    if empty?
-      "Matrix.empty(#{row_size}, #{column_size})"
-    else
-      "Matrix#{@rows.inspect}"
-    end
-  end
-
-  # Private helper modules
-
-  module ConversionHelper # :nodoc:
-    #
-    # Converts the obj to an Array. If copy is set to true
-    # a copy of obj will be made if necessary.
-    #
-    def convert_to_array(obj, copy = false) # :nodoc:
-      case obj
-      when Array
-        copy ? obj.dup : obj
-      when Vector
-        obj.to_a
-      else
-        begin
-          converted = obj.to_ary
-        rescue Exception => e
-          raise TypeError, "can't convert #{obj.class} into an Array (#{e.message})"
-        end
-        raise TypeError, "#{obj.class}#to_ary should return an Array" unless converted.is_a? Array
-        converted
-      end
-    end
-    private :convert_to_array
-  end
-
-  extend ConversionHelper
-
-  module CoercionHelper # :nodoc:
-    #
-    # Applies the operator +oper+ with argument +obj+
-    # through coercion of +obj+
-    #
-    def apply_through_coercion(obj, oper)
-      coercion = obj.coerce(self)
-      raise TypeError unless coercion.is_a?(Array) && coercion.length == 2
-      coercion[0].public_send(oper, coercion[1])
-    rescue
-      raise TypeError, "#{obj.inspect} can't be coerced into #{self.class}"
-    end
-    private :apply_through_coercion
-
-    #
-    # Helper method to coerce a value into a specific class.
-    # Raises a TypeError if the coercion fails or the returned value
-    # is not of the right class.
-    # (from Rubinius)
-    #
-    def self.coerce_to(obj, cls, meth) # :nodoc:
-      return obj if obj.kind_of?(cls)
-
-      begin
-        ret = obj.__send__(meth)
-      rescue Exception => e
-        raise TypeError, "Coercion error: #{obj.inspect}.#{meth} => #{cls} failed:\n" \
-                         "(#{e.message})"
-      end
-      raise TypeError, "Coercion error: obj.#{meth} did NOT return a #{cls} (was #{ret.class})" unless ret.kind_of? cls
-      ret
-    end
-
-    def self.coerce_to_int(obj)
-      coerce_to(obj, Integer, :to_int)
-    end
-  end
-
-  include CoercionHelper
-
-  # Private CLASS
-
-  class Scalar < Numeric # :nodoc:
-    include ExceptionForMatrix
-    include CoercionHelper
-
-    def initialize(value)
-      @value = value
-    end
-
-    # ARITHMETIC
-    def +(other)
-      case other
-      when Numeric
-        Scalar.new(@value + other)
-      when Vector, Matrix
-        Scalar.Raise ErrOperationNotDefined, "+", @value.class, other.class
-      else
-        apply_through_coercion(other, __method__)
-      end
-    end
-
-    def -(other)
-      case other
-      when Numeric
-        Scalar.new(@value - other)
-      when Vector, Matrix
-        Scalar.Raise ErrOperationNotDefined, "-", @value.class, other.class
-      else
-        apply_through_coercion(other, __method__)
-      end
-    end
-
-    def *(other)
-      case other
-      when Numeric
-        Scalar.new(@value * other)
-      when Vector, Matrix
-        other.collect{|e| @value * e}
-      else
-        apply_through_coercion(other, __method__)
-      end
-    end
-
-    def / (other)
-      case other
-      when Numeric
-        Scalar.new(@value / other)
-      when Vector
-        Scalar.Raise ErrOperationNotDefined, "/", @value.class, other.class
-      when Matrix
-        self * other.inverse
-      else
-        apply_through_coercion(other, __method__)
-      end
-    end
-
-    def ** (other)
-      case other
-      when Numeric
-        Scalar.new(@value ** other)
-      when Vector
-        Scalar.Raise ErrOperationNotDefined, "**", @value.class, other.class
-      when Matrix
-        #other.powered_by(self)
-        Scalar.Raise ErrOperationNotImplemented, "**", @value.class, other.class
-      else
-        apply_through_coercion(other, __method__)
-      end
-    end
-  end
-
-end
-
-
-#
-# The +Vector+ class represents a mathematical vector, which is useful in its own right, and
-# also constitutes a row or column of a Matrix.
-#
-# == Method Catalogue
-#
-# To create a Vector:
-# * <tt>  Vector.[](*array)                   </tt>
-# * <tt>  Vector.elements(array, copy = true) </tt>
-#
-# To access elements:
-# * <tt>  [](i)                               </tt>
-#
-# To enumerate the elements:
-# * <tt> #each2(v)                            </tt>
-# * <tt> #collect2(v)                         </tt>
-#
-# Vector arithmetic:
-# * <tt>  *(x) "is matrix or number"          </tt>
-# * <tt>  +(v)                                </tt>
-# * <tt>  -(v)                                </tt>
-#
-# Vector functions:
-# * <tt> #inner_product(v)                    </tt>
-# * <tt> #collect                             </tt>
-# * <tt> #magnitude                           </tt>
-# * <tt> #map                                 </tt>
-# * <tt> #map2(v)                             </tt>
-# * <tt> #norm                                </tt>
-# * <tt> #normalize                           </tt>
-# * <tt> #r                                   </tt>
-# * <tt> #size                                </tt>
-#
-# Conversion to other data types:
-# * <tt> #covector                            </tt>
-# * <tt> #to_a                                </tt>
-# * <tt> #coerce(other)                       </tt>
-#
-# String representations:
-# * <tt> #to_s                                </tt>
-# * <tt> #inspect                             </tt>
-#
-class Vector
-  include ExceptionForMatrix
-  include Enumerable
-  include Matrix::CoercionHelper
-  extend Matrix::ConversionHelper
-  #INSTANCE CREATION
-
-  private_class_method :new
-  attr_reader :elements
-  protected :elements
-
-  #
-  # Creates a Vector from a list of elements.
-  #   Vector[7, 4, ...]
-  #
-  def Vector.[](*array)
-    new convert_to_array(array, false)
-  end
-
-  #
-  # Creates a vector from an Array.  The optional second argument specifies
-  # whether the array itself or a copy is used internally.
-  #
-  def Vector.elements(array, copy = true)
-    new convert_to_array(array, copy)
-  end
-
-  #
-  # Vector.new is private; use Vector[] or Vector.elements to create.
-  #
-  def initialize(array)
-    # No checking is done at this point.
-    @elements = array
-  end
-
-  # ACCESSING
-
-  #
-  # Returns element number +i+ (starting at zero) of the vector.
-  #
-  def [](i)
-    @elements[i]
-  end
-  alias element []
-  alias component []
-
-  def []=(i, v)
-    @elements[i]= v
-  end
-  alias set_element []=
-  alias set_component []=
-  private :[]=, :set_element, :set_component
-
-  #
-  # Returns the number of elements in the vector.
-  #
-  def size
-    @elements.size
-  end
-
-  #--
-  # ENUMERATIONS -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
-  #++
-
-  #
-  # Iterate over the elements of this vector
-  #
-  def each(&block)
-    return to_enum(:each) unless block_given?
-    @elements.each(&block)
-    self
-  end
-
-  #
-  # Iterate over the elements of this vector and +v+ in conjunction.
-  #
-  def each2(v) # :yield: e1, e2
-    raise TypeError, "Integer is not like Vector" if v.kind_of?(Integer)
-    Vector.Raise ErrDimensionMismatch if size != v.size
-    return to_enum(:each2, v) unless block_given?
-    size.times do |i|
-      yield @elements[i], v[i]
-    end
-    self
-  end
-
-  #
-  # Collects (as in Enumerable#collect) over the elements of this vector and +v+
-  # in conjunction.
-  #
-  def collect2(v) # :yield: e1, e2
-    raise TypeError, "Integer is not like Vector" if v.kind_of?(Integer)
-    Vector.Raise ErrDimensionMismatch if size != v.size
-    return to_enum(:collect2, v) unless block_given?
-    Array.new(size) do |i|
-      yield @elements[i], v[i]
-    end
-  end
-
-  #--
-  # COMPARING -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
-  #++
-
-  #
-  # Returns +true+ iff the two vectors have the same elements in the same order.
-  #
-  def ==(other)
-    return false unless Vector === other
-    @elements == other.elements
-  end
-
-  def eql?(other)
-    return false unless Vector === other
-    @elements.eql? other.elements
-  end
-
-  #
-  # Return a copy of the vector.
-  #
-  def clone
-    Vector.elements(@elements)
-  end
-
-  #
-  # Return a hash-code for the vector.
-  #
-  def hash
-    @elements.hash
-  end
-
-  #--
-  # ARITHMETIC -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
-  #++
-
-  #
-  # Multiplies the vector by +x+, where +x+ is a number or another vector.
-  #
-  def *(x)
-    case x
-    when Numeric
-      els = @elements.collect{|e| e * x}
-      Vector.elements(els, false)
-    when Matrix
-      Matrix.column_vector(self) * x
-    when Vector
-      Vector.Raise ErrOperationNotDefined, "*", self.class, x.class
-    else
-      apply_through_coercion(x, __method__)
-    end
-  end
-
-  #
-  # Vector addition.
-  #
-  def +(v)
-    case v
-    when Vector
-      Vector.Raise ErrDimensionMismatch if size != v.size
-      els = collect2(v) {|v1, v2|
-        v1 + v2
-      }
-      Vector.elements(els, false)
-    when Matrix
-      Matrix.column_vector(self) + v
-    else
-      apply_through_coercion(v, __method__)
-    end
-  end
-
-  #
-  # Vector subtraction.
-  #
-  def -(v)
-    case v
-    when Vector
-      Vector.Raise ErrDimensionMismatch if size != v.size
-      els = collect2(v) {|v1, v2|
-        v1 - v2
-      }
-      Vector.elements(els, false)
-    when Matrix
-      Matrix.column_vector(self) - v
-    else
-      apply_through_coercion(v, __method__)
-    end
-  end
-
-  #
-  # Vector division.
-  #
-  def /(x)
-    case x
-    when Numeric
-      els = @elements.collect{|e| e / x}
-      Vector.elements(els, false)
-    when Matrix, Vector
-      Vector.Raise ErrOperationNotDefined, "/", self.class, x.class
-    else
-      apply_through_coercion(x, __method__)
-    end
-  end
-
-  #--
-  # VECTOR FUNCTIONS -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
-  #++
-
-  #
-  # Returns the inner product of this vector with the other.
-  #   Vector[4,7].inner_product Vector[10,1]  => 47
-  #
-  def inner_product(v)
-    Vector.Raise ErrDimensionMismatch if size != v.size
-
-    p = 0
-    each2(v) {|v1, v2|
-      p += v1 * v2
-    }
-    p
-  end
-
-  #
-  # Like Array#collect.
-  #
-  def collect(&block) # :yield: e
-    return to_enum(:collect) unless block_given?
-    els = @elements.collect(&block)
-    Vector.elements(els, false)
-  end
-  alias map collect
-
-  #
-  # Returns the modulus (Pythagorean distance) of the vector.
-  #   Vector[5,8,2].r => 9.643650761
-  #
-  def magnitude
-    Math.sqrt(@elements.inject(0) {|v, e| v + e*e})
-  end
-  alias r magnitude
-  alias norm magnitude
-
-  #
-  # Like Vector#collect2, but returns a Vector instead of an Array.
-  #
-  def map2(v, &block) # :yield: e1, e2
-    return to_enum(:map2, v) unless block_given?
-    els = collect2(v, &block)
-    Vector.elements(els, false)
-  end
-
-  class ZeroVectorError < StandardError
-  end
-  #
-  # Returns a new vector with the same direction but with norm 1.
-  #   v = Vector[5,8,2].normalize
-  #   # => Vector[0.5184758473652127, 0.8295613557843402, 0.20739033894608505]
-  #   v.norm => 1.0
-  #
-  def normalize
-    n = magnitude
-    raise ZeroVectorError, "Zero vectors can not be normalized" if n == 0
-    self / n
-  end
-
-  #--
-  # CONVERTING
-  #++
-
-  #
-  # Creates a single-row matrix from this vector.
-  #
-  def covector
-    Matrix.row_vector(self)
-  end
-
-  #
-  # Returns the elements of the vector in an array.
-  #
-  def to_a
-    @elements.dup
-  end
-
-  def elements_to_f
-    warn "#{caller(1)[0]}: warning: Vector#elements_to_f is deprecated"
-    map(&:to_f)
-  end
-
-  def elements_to_i
-    warn "#{caller(1)[0]}: warning: Vector#elements_to_i is deprecated"
-    map(&:to_i)
-  end
-
-  def elements_to_r
-    warn "#{caller(1)[0]}: warning: Vector#elements_to_r is deprecated"
-    map(&:to_r)
-  end
-
-  #
-  # The coerce method provides support for Ruby type coercion.
-  # This coercion mechanism is used by Ruby to handle mixed-type
-  # numeric operations: it is intended to find a compatible common
-  # type between the two operands of the operator.
-  # See also Numeric#coerce.
-  #
-  def coerce(other)
-    case other
-    when Numeric
-      return Matrix::Scalar.new(other), self
-    else
-      raise TypeError, "#{self.class} can't be coerced into #{other.class}"
-    end
-  end
-
-  #--
-  # PRINTING -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
-  #++
-
-  #
-  # Overrides Object#to_s
-  #
-  def to_s
-    "Vector[" + @elements.join(", ") + "]"
-  end
-
-  #
-  # Overrides Object#inspect
-  #
-  def inspect
-    "Vector" + @elements.inspect
-  end
-end
diff --git a/lib/matrix/eigenvalue_decomposition.rb b/lib/matrix/eigenvalue_decomposition.rb
deleted file mode 100644
index 55e41aaf7c..0000000000
--- a/lib/matrix/eigenvalue_decomposition.rb
+++ /dev/null
@@ -1,886 +0,0 @@
-class Matrix
-  # Adapted from JAMA: http://math.nist.gov/javanumerics/jama/
-
-  # Eigenvalues and eigenvectors of a real matrix.
-  #
-  # Computes the eigenvalues and eigenvectors of a matrix A.
-  #
-  # If A is diagonalizable, this provides matrices V and D
-  # such that A = V*D*V.inv, where D is the diagonal matrix with entries
-  # equal to the eigenvalues and V is formed by the eigenvectors.
-  #
-  # If A is symmetric, then V is orthogonal and thus A = V*D*V.t
-
-  class EigenvalueDecomposition
-
-    # Constructs the eigenvalue decomposition for a square matrix +A+
-    #
-    def initialize(a)
-      # @d, @e: Arrays for internal storage of eigenvalues.
-      # @v: Array for internal storage of eigenvectors.
-      # @h: Array for internal storage of nonsymmetric Hessenberg form.
-      raise TypeError, "Expected Matrix but got #{a.class}" unless a.is_a?(Matrix)
-      @size = a.row_size
-      @d = Array.new(@size, 0)
-      @e = Array.new(@size, 0)
-
-      if (@symmetric = a.symmetric?)
-        @v = a.to_a
-        tridiagonalize
-        diagonalize
-      else
-        @v = Array.new(@size) { Array.new(@size, 0) }
-        @h = a.to_a
-        @ort = Array.new(@size, 0)
-        reduce_to_hessenberg
-        hessenberg_to_real_schur
-      end
-    end
-
-    # Returns the eigenvector matrix +V+
-    #
-    def eigenvector_matrix
-      Matrix.send :new, build_eigenvectors.transpose
-    end
-    alias v eigenvector_matrix
-
-    # Returns the inverse of the eigenvector matrix +V+
-    #
-    def eigenvector_matrix_inv
-      r = Matrix.send :new, build_eigenvectors
-      r = r.transpose.inverse unless @symmetric
-      r
-    end
-    alias v_inv eigenvector_matrix_inv
-
-    # Returns the eigenvalues in an array
-    #
-    def eigenvalues
-      values = @d.dup
-      @e.each_with_index{|imag, i| values[i] = Complex(values[i], imag) unless imag == 0}
-      values
-    end
-
-    # Returns an array of the eigenvectors
-    #
-    def eigenvectors
-      build_eigenvectors.map{|ev| Vector.send :new, ev}
-    end
-
-    # Returns the block diagonal eigenvalue matrix +D+
-    #
-    def eigenvalue_matrix
-      Matrix.diagonal(*eigenvalues)
-    end
-    alias d eigenvalue_matrix
-
-    # Returns [eigenvector_matrix, eigenvalue_matrix, eigenvector_matrix_inv]
-    #
-    def to_ary
-      [v, d, v_inv]
-    end
-    alias_method :to_a, :to_ary
-
-  private
-    def build_eigenvectors
-      # JAMA stores complex eigenvectors in a strange way
-      # See http://cio.nist.gov/esd/emaildir/lists/jama/msg01021.html
-      @e.each_with_index.map do |imag, i|
-        if imag == 0
-          Array.new(@size){|j| @v[j][i]}
-        elsif imag > 0
-          Array.new(@size){|j| Complex(@v[j][i], @v[j][i+1])}
-        else
-          Array.new(@size){|j| Complex(@v[j][i], -@v[j][i-1])}
-        end
-      end
-    end
-    # Complex scalar division.
-
-    def cdiv(xr, xi, yr, yi)
-      if (yr.abs > yi.abs)
-        r = yi/yr
-        d = yr + r*yi
-        [(xr + r*xi)/d, (xi - r*xr)/d]
-      else
-        r = yr/yi
-        d = yi + r*yr
-        [(r*xr + xi)/d, (r*xi - xr)/d]
-      end
-    end
-
-
-    # Symmetric Householder reduction to tridiagonal form.
-
-    def tridiagonalize
-
-      #  This is derived from the Algol procedures tred2 by
-      #  Bowdler, Martin, Reinsch, and Wilkinson, Handbook for
-      #  Auto. Comp., Vol.ii-Linear Algebra, and the corresponding
-      #  Fortran subroutine in EISPACK.
-
-        @size.times do |j|
-          @d[j] = @v[@size-1][j]
-        end
-
-        # Householder reduction to tridiagonal form.
-
-        (@size-1).downto(0+1) do |i|
-
-          # Scale to avoid under/overflow.
-
-          scale = 0.0
-          h = 0.0
-          i.times do |k|
-            scale = scale + @d[k].abs
-          end
-          if (scale == 0.0)
-            @e[i] = @d[i-1]
-            i.times do |j|
-              @d[j] = @v[i-1][j]
-              @v[i][j] = 0.0
-              @v[j][i] = 0.0
-            end
-          else
-
-            # Generate Householder vector.
-
-            i.times do |k|
-              @d[k] /= scale
-              h += @d[k] * @d[k]
-            end
-            f = @d[i-1]
-            g = Math.sqrt(h)
-            if (f > 0)
-              g = -g
-            end
-            @e[i] = scale * g
-            h -= f * g
-            @d[i-1] = f - g
-            i.times do |j|
-              @e[j] = 0.0
-            end
-
-            # Apply similarity transformation to remaining columns.
-
-            i.times do |j|
-              f = @d[j]
-              @v[j][i] = f
-              g = @e[j] + @v[j][j] * f
-              (j+1).upto(i-1) do |k|
-                g += @v[k][j] * @d[k]
-                @e[k] += @v[k][j] * f
-              end
-              @e[j] = g
-            end
-            f = 0.0
-            i.times do |j|
-              @e[j] /= h
-              f += @e[j] * @d[j]
-            end
-            hh = f / (h + h)
-            i.times do |j|
-              @e[j] -= hh * @d[j]
-            end
-            i.times do |j|
-              f = @d[j]
-              g = @e[j]
-              j.upto(i-1) do |k|
-                @v[k][j] -= (f * @e[k] + g * @d[k])
-              end
-              @d[j] = @v[i-1][j]
-              @v[i][j] = 0.0
-            end
-          end
-          @d[i] = h
-        end
-
-        # Accumulate transformations.
-
-        0.upto(@size-1-1) do |i|
-          @v[@size-1][i] = @v[i][i]
-          @v[i][i] = 1.0
-          h = @d[i+1]
-          if (h != 0.0)
-            0.upto(i) do |k|
-              @d[k] = @v[k][i+1] / h
-            end
-            0.upto(i) do |j|
-              g = 0.0
-              0.upto(i) do |k|
-                g += @v[k][i+1] * @v[k][j]
-              end
-              0.upto(i) do |k|
-                @v[k][j] -= g * @d[k]
-              end
-            end
-          end
-          0.upto(i) do |k|
-            @v[k][i+1] = 0.0
-          end
-        end
-        @size.times do |j|
-          @d[j] = @v[@size-1][j]
-          @v[@size-1][j] = 0.0
-        end
-        @v[@size-1][@size-1] = 1.0
-        @e[0] = 0.0
-      end
-
-
-    # Symmetric tridiagonal QL algorithm.
-
-    def diagonalize
-      #  This is derived from the Algol procedures tql2, by
-      #  Bowdler, Martin, Reinsch, and Wilkinson, Handbook for
-      #  Auto. Comp., Vol.ii-Linear Algebra, and the corresponding
-      #  Fortran subroutine in EISPACK.
-
-      1.upto(@size-1) do |i|
-        @e[i-1] = @e[i]
-      end
-      @e[@size-1] = 0.0
-
-      f = 0.0
-      tst1 = 0.0
-      eps = Float::EPSILON
-      @size.times do |l|
-
-        # Find small subdiagonal element
-
-        tst1 = [tst1, @d[l].abs + @e[l].abs].max
-        m = l
-        while (m < @size) do
-          if (@e[m].abs <= eps*tst1)
-            break
-          end
-          m+=1
-        end
-
-        # If m == l, @d[l] is an eigenvalue,
-        # otherwise, iterate.
-
-        if (m > l)
-          iter = 0
-          begin
-            iter = iter + 1  # (Could check iteration count here.)
-
-            # Compute implicit shift
-
-            g = @d[l]
-            p = (@d[l+1] - g) / (2.0 * @e[l])
-            r = Math.hypot(p, 1.0)
-            if (p < 0)
-              r = -r
-            end
-            @d[l] = @e[l] / (p + r)
-            @d[l+1] = @e[l] * (p + r)
-            dl1 = @d[l+1]
-            h = g - @d[l]
-            (l+2).upto(@size-1) do |i|
-              @d[i] -= h
-            end
-            f += h
-
-            # Implicit QL transformation.
-
-            p = @d[m]
-            c = 1.0
-            c2 = c
-            c3 = c
-            el1 = @e[l+1]
-            s = 0.0
-            s2 = 0.0
-            (m-1).downto(l) do |i|
-              c3 = c2
-              c2 = c
-              s2 = s
-              g = c * @e[i]
-              h = c * p
-              r = Math.hypot(p, @e[i])
-              @e[i+1] = s * r
-              s = @e[i] / r
-              c = p / r
-              p = c * @d[i] - s * g
-              @d[i+1] = h + s * (c * g + s * @d[i])
-
-              # Accumulate transformation.
-
-              @size.times do |k|
-                h = @v[k][i+1]
-                @v[k][i+1] = s * @v[k][i] + c * h
-                @v[k][i] = c * @v[k][i] - s * h
-              end
-            end
-            p = -s * s2 * c3 * el1 * @e[l] / dl1
-            @e[l] = s * p
-            @d[l] = c * p
-
-            # Check for convergence.
-
-          end while (@e[l].abs > eps*tst1)
-        end
-        @d[l] = @d[l] + f
-        @e[l] = 0.0
-      end
-
-      # Sort eigenvalues and corresponding vectors.
-
-      0.upto(@size-2) do |i|
-        k = i
-        p = @d[i]
-        (i+1).upto(@size-1) do |j|
-          if (@d[j] < p)
-            k = j
-            p = @d[j]
-          end
-        end
-        if (k != i)
-          @d[k] = @d[i]
-          @d[i] = p
-          @size.times do |j|
-            p = @v[j][i]
-            @v[j][i] = @v[j][k]
-            @v[j][k] = p
-          end
-        end
-      end
-    end
-
-    # Nonsymmetric reduction to Hessenberg form.
-
-    def reduce_to_hessenberg
-      #  This is derived from the Algol procedures orthes and ortran,
-      #  by Martin and Wilkinson, Handbook for Auto. Comp.,
-      #  Vol.ii-Linear Algebra, and the corresponding
-      #  Fortran subroutines in EISPACK.
-
-      low = 0
-      high = @size-1
-
-      (low+1).upto(high-1) do |m|
-
-        # Scale column.
-
-        scale = 0.0
-        m.upto(high) do |i|
-          scale = scale + @h[i][m-1].abs
-        end
-        if (scale != 0.0)
-
-          # Compute Householder transformation.
-
-          h = 0.0
-          high.downto(m) do |i|
-            @ort[i] = @h[i][m-1]/scale
-            h += @ort[i] * @ort[i]
-          end
-          g = Math.sqrt(h)
-          if (@ort[m] > 0)
-            g = -g
-          end
-          h -= @ort[m] * g
-          @ort[m] = @ort[m] - g
-
-          # Apply Householder similarity transformation
-          # @h = (I-u*u'/h)*@h*(I-u*u')/h)
-
-          m.upto(@size-1) do |j|
-            f = 0.0
-            high.downto(m) do |i|
-              f += @ort[i]*@h[i][j]
-            end
-            f = f/h
-            m.upto(high) do |i|
-              @h[i][j] -= f*@ort[i]
-            end
-          end
-
-          0.upto(high) do |i|
-            f = 0.0
-            high.downto(m) do |j|
-              f += @ort[j]*@h[i][j]
-            end
-            f = f/h
-            m.upto(high) do |j|
-              @h[i][j] -= f*@ort[j]
-            end
-          end
-          @ort[m] = scale*@ort[m]
-          @h[m][m-1] = scale*g
-        end
-      end
-
-      # Accumulate transformations (Algol's ortran).
-
-      @size.times do |i|
-        @size.times do |j|
-          @v[i][j] = (i == j ? 1.0 : 0.0)
-        end
-      end
-
-      (high-1).downto(low+1) do |m|
-        if (@h[m][m-1] != 0.0)
-          (m+1).upto(high) do |i|
-            @ort[i] = @h[i][m-1]
-          end
-          m.upto(high) do |j|
-            g = 0.0
-            m.upto(high) do |i|
-              g += @ort[i] * @v[i][j]
-            end
-            # Double division avoids possible underflow
-            g = (g / @ort[m]) / @h[m][m-1]
-            m.upto(high) do |i|
-              @v[i][j] += g * @ort[i]
-            end
-          end
-        end
-      end
-    end
-
-
-
-    # Nonsymmetric reduction from Hessenberg to real Schur form.
-
-    def hessenberg_to_real_schur
-
-      #  This is derived from the Algol procedure hqr2,
-      #  by Martin and Wilkinson, Handbook for Auto. Comp.,
-      #  Vol.ii-Linear Algebra, and the corresponding
-      #  Fortran subroutine in EISPACK.
-
-      # Initialize
-
-      nn = @size
-      n = nn-1
-      low = 0
-      high = nn-1
-      eps = Float::EPSILON
-      exshift = 0.0
-      p=q=r=s=z=0
-
-      # Store roots isolated by balanc and compute matrix norm
-
-      norm = 0.0
-      nn.times do |i|
-        if (i < low || i > high)
-          @d[i] = @h[i][i]
-          @e[i] = 0.0
-        end
-        ([i-1, 0].max).upto(nn-1) do |j|
-          norm = norm + @h[i][j].abs
-        end
-      end
-
-      # Outer loop over eigenvalue index
-
-      iter = 0
-      while (n >= low) do
-
-        # Look for single small sub-diagonal element
-
-        l = n
-        while (l > low) do
-          s = @h[l-1][l-1].abs + @h[l][l].abs
-          if (s == 0.0)
-            s = norm
-          end
-          if (@h[l][l-1].abs < eps * s)
-            break
-          end
-          l-=1
-        end
-
-        # Check for convergence
-        # One root found
-
-        if (l == n)
-          @h[n][n] = @h[n][n] + exshift
-          @d[n] = @h[n][n]
-          @e[n] = 0.0
-          n-=1
-          iter = 0
-
-        # Two roots found
-
-        elsif (l == n-1)
-          w = @h[n][n-1] * @h[n-1][n]
-          p = (@h[n-1][n-1] - @h[n][n]) / 2.0
-          q = p * p + w
-          z = Math.sqrt(q.abs)
-          @h[n][n] = @h[n][n] + exshift
-          @h[n-1][n-1] = @h[n-1][n-1] + exshift
-          x = @h[n][n]
-
-          # Real pair
-
-          if (q >= 0)
-            if (p >= 0)
-              z = p + z
-            else
-              z = p - z
-            end
-            @d[n-1] = x + z
-            @d[n] = @d[n-1]
-            if (z != 0.0)
-              @d[n] = x - w / z
-            end
-            @e[n-1] = 0.0
-            @e[n] = 0.0
-            x = @h[n][n-1]
-            s = x.abs + z.abs
-            p = x / s
-            q = z / s
-            r = Math.sqrt(p * p+q * q)
-            p /= r
-            q /= r
-
-            # Row modification
-
-            (n-1).upto(nn-1) do |j|
-              z = @h[n-1][j]
-              @h[n-1][j] = q * z + p * @h[n][j]
-              @h[n][j] = q * @h[n][j] - p * z
-            end
-
-            # Column modification
-
-            0.upto(n) do |i|
-              z = @h[i][n-1]
-              @h[i][n-1] = q * z + p * @h[i][n]
-              @h[i][n] = q * @h[i][n] - p * z
-            end
-
-            # Accumulate transformations
-
-            low.upto(high) do |i|
-              z = @v[i][n-1]
-              @v[i][n-1] = q * z + p * @v[i][n]
-              @v[i][n] = q * @v[i][n] - p * z
-            end
-
-          # Complex pair
-
-          else
-            @d[n-1] = x + p
-            @d[n] = x + p
-            @e[n-1] = z
-            @e[n] = -z
-          end
-          n -= 2
-          iter = 0
-
-        # No convergence yet
-
-        else
-
-          # Form shift
-
-          x = @h[n][n]
-          y = 0.0
-          w = 0.0
-          if (l < n)
-            y = @h[n-1][n-1]
-            w = @h[n][n-1] * @h[n-1][n]
-          end
-
-          # Wilkinson's original ad hoc shift
-
-          if (iter == 10)
-            exshift += x
-            low.upto(n) do |i|
-              @h[i][i] -= x
-            end
-            s = @h[n][n-1].abs + @h[n-1][n-2].abs
-            x = y = 0.75 * s
-            w = -0.4375 * s * s
-          end
-
-          # MATLAB's new ad hoc shift
-
-          if (iter == 30)
-             s = (y - x) / 2.0
-             s *= s + w
-             if (s > 0)
-                s = Math.sqrt(s)
-                if (y < x)
-                  s = -s
-                end
-                s = x - w / ((y - x) / 2.0 + s)
-                low.upto(n) do |i|
-                  @h[i][i] -= s
-                end
-                exshift += s
-                x = y = w = 0.964
-             end
-          end
-
-          iter = iter + 1  # (Could check iteration count here.)
-
-          # Look for two consecutive small sub-diagonal elements
-
-          m = n-2
-          while (m >= l) do
-            z = @h[m][m]
-            r = x - z
-            s = y - z
-            p = (r * s - w) / @h[m+1][m] + @h[m][m+1]
-            q = @h[m+1][m+1] - z - r - s
-            r = @h[m+2][m+1]
-            s = p.abs + q.abs + r.abs
-            p /= s
-            q /= s
-            r /= s
-            if (m == l)
-              break
-            end
-            if (@h[m][m-1].abs * (q.abs + r.abs) <
-              eps * (p.abs * (@h[m-1][m-1].abs + z.abs +
-              @h[m+1][m+1].abs)))
-                break
-            end
-            m-=1
-          end
-
-          (m+2).upto(n) do |i|
-            @h[i][i-2] = 0.0
-            if (i > m+2)
-              @h[i][i-3] = 0.0
-            end
-          end
-
-          # Double QR step involving rows l:n and columns m:n
-
-          m.upto(n-1) do |k|
-            notlast = (k != n-1)
-            if (k != m)
-              p = @h[k][k-1]
-              q = @h[k+1][k-1]
-              r = (notlast ? @h[k+2][k-1] : 0.0)
-              x = p.abs + q.abs + r.abs
-              if (x != 0.0)
-                p /= x
-                q /= x
-                r /= x
-              end
-            end
-            if (x == 0.0)
-              break
-            end
-            s = Math.sqrt(p * p + q * q + r * r)
-            if (p < 0)
-              s = -s
-            end
-            if (s != 0)
-              if (k != m)
-                @h[k][k-1] = -s * x
-              elsif (l != m)
-                @h[k][k-1] = -@h[k][k-1]
-              end
-              p += s
-              x = p / s
-              y = q / s
-              z = r / s
-              q /= p
-              r /= p
-
-              # Row modification
-
-              k.upto(nn-1) do |j|
-                p = @h[k][j] + q * @h[k+1][j]
-                if (notlast)
-                  p += r * @h[k+2][j]
-                  @h[k+2][j] = @h[k+2][j] - p * z
-                end
-                @h[k][j] = @h[k][j] - p * x
-                @h[k+1][j] = @h[k+1][j] - p * y
-              end
-
-              # Column modification
-
-              0.upto([n, k+3].min) do |i|
-                p = x * @h[i][k] + y * @h[i][k+1]
-                if (notlast)
-                  p += z * @h[i][k+2]
-                  @h[i][k+2] = @h[i][k+2] - p * r
-                end
-                @h[i][k] = @h[i][k] - p
-                @h[i][k+1] = @h[i][k+1] - p * q
-              end
-
-              # Accumulate transformations
-
-              low.upto(high) do |i|
-                p = x * @v[i][k] + y * @v[i][k+1]
-                if (notlast)
-                  p += z * @v[i][k+2]
-                  @v[i][k+2] = @v[i][k+2] - p * r
-                end
-                @v[i][k] = @v[i][k] - p
-                @v[i][k+1] = @v[i][k+1] - p * q
-              end
-            end  # (s != 0)
-          end  # k loop
-        end  # check convergence
-      end  # while (n >= low)
-
-      # Backsubstitute to find vectors of upper triangular form
-
-      if (norm == 0.0)
-        return
-      end
-
-      (nn-1).downto(0) do |n|
-        p = @d[n]
-        q = @e[n]
-
-        # Real vector
-
-        if (q == 0)
-          l = n
-          @h[n][n] = 1.0
-          (n-1).downto(0) do |i|
-            w = @h[i][i] - p
-            r = 0.0
-            l.upto(n) do |j|
-              r += @h[i][j] * @h[j][n]
-            end
-            if (@e[i] < 0.0)
-              z = w
-              s = r
-            else
-              l = i
-              if (@e[i] == 0.0)
-                if (w != 0.0)
-                  @h[i][n] = -r / w
-                else
-                  @h[i][n] = -r / (eps * norm)
-                end
-
-              # Solve real equations
-
-              else
-                x = @h[i][i+1]
-                y = @h[i+1][i]
-                q = (@d[i] - p) * (@d[i] - p) + @e[i] * @e[i]
-                t = (x * s - z * r) / q
-                @h[i][n] = t
-                if (x.abs > z.abs)
-                  @h[i+1][n] = (-r - w * t) / x
-                else
-                  @h[i+1][n] = (-s - y * t) / z
-                end
-              end
-
-              # Overflow control
-
-              t = @h[i][n].abs
-              if ((eps * t) * t > 1)
-                i.upto(n) do |j|
-                  @h[j][n] = @h[j][n] / t
-                end
-              end
-            end
-          end
-
-        # Complex vector
-
-        elsif (q < 0)
-          l = n-1
-
-          # Last vector component imaginary so matrix is triangular
-
-          if (@h[n][n-1].abs > @h[n-1][n].abs)
-            @h[n-1][n-1] = q / @h[n][n-1]
-            @h[n-1][n] = -(@h[n][n] - p) / @h[n][n-1]
-          else
-            cdivr, cdivi = cdiv(0.0, -@h[n-1][n], @h[n-1][n-1]-p, q)
-            @h[n-1][n-1] = cdivr
-            @h[n-1][n] = cdivi
-          end
-          @h[n][n-1] = 0.0
-          @h[n][n] = 1.0
-          (n-2).downto(0) do |i|
-            ra = 0.0
-            sa = 0.0
-            l.upto(n) do |j|
-              ra = ra + @h[i][j] * @h[j][n-1]
-              sa = sa + @h[i][j] * @h[j][n]
-            end
-            w = @h[i][i] - p
-
-            if (@e[i] < 0.0)
-              z = w
-              r = ra
-              s = sa
-            else
-              l = i
-              if (@e[i] == 0)
-                cdivr, cdivi = cdiv(-ra, -sa, w, q)
-                @h[i][n-1] = cdivr
-                @h[i][n] = cdivi
-              else
-
-                # Solve complex equations
-
-                x = @h[i][i+1]
-                y = @h[i+1][i]
-                vr = (@d[i] - p) * (@d[i] - p) + @e[i] * @e[i] - q * q
-                vi = (@d[i] - p) * 2.0 * q
-                if (vr == 0.0 && vi == 0.0)
-                  vr = eps * norm * (w.abs + q.abs +
-                  x.abs + y.abs + z.abs)
-                end
-                cdivr, cdivi = cdiv(x*r-z*ra+q*sa, x*s-z*sa-q*ra, vr, vi)
-                @h[i][n-1] = cdivr
-                @h[i][n] = cdivi
-                if (x.abs > (z.abs + q.abs))
-                  @h[i+1][n-1] = (-ra - w * @h[i][n-1] + q * @h[i][n]) / x
-                  @h[i+1][n] = (-sa - w * @h[i][n] - q * @h[i][n-1]) / x
-                else
-                  cdivr, cdivi = cdiv(-r-y*@h[i][n-1], -s-y*@h[i][n], z, q)
-                  @h[i+1][n-1] = cdivr
-                  @h[i+1][n] = cdivi
-                end
-              end
-
-              # Overflow control
-
-              t = [@h[i][n-1].abs, @h[i][n].abs].max
-              if ((eps * t) * t > 1)
-                i.upto(n) do |j|
-                  @h[j][n-1] = @h[j][n-1] / t
-                  @h[j][n] = @h[j][n] / t
-                end
-              end
-            end
-          end
-        end
-      end
-
-      # Vectors of isolated roots
-
-      nn.times do |i|
-        if (i < low || i > high)
-          i.upto(nn-1) do |j|
-            @v[i][j] = @h[i][j]
-          end
-        end
-      end
-
-      # Back transformation to get eigenvectors of original matrix
-
-      (nn-1).downto(low) do |j|
-        low.upto(high) do |i|
-          z = 0.0
-          low.upto([j, high].min) do |k|
-            z += @v[i][k] * @h[k][j]
-          end
-          @v[i][j] = z
-        end
-      end
-    end
-
-  end
-end
diff --git a/lib/matrix/lup_decomposition.rb b/lib/matrix/lup_decomposition.rb
deleted file mode 100644
index 8f5aac2e5a..0000000000
--- a/lib/matrix/lup_decomposition.rb
+++ /dev/null
@@ -1,218 +0,0 @@
-class Matrix
-  # Adapted from JAMA: http://math.nist.gov/javanumerics/jama/
-
-  #
-  # For an m-by-n matrix A with m >= n, the LU decomposition is an m-by-n
-  # unit lower triangular matrix L, an n-by-n upper triangular matrix U,
-  # and a m-by-m permutation matrix P so that L*U = P*A.
-  # If m < n, then L is m-by-m and U is m-by-n.
-  #
-  # The LUP decomposition with pivoting always exists, even if the matrix is
-  # singular, so the constructor will never fail.  The primary use of the
-  # LU decomposition is in the solution of square systems of simultaneous
-  # linear equations.  This will fail if singular? returns true.
-  #
-
-  class LUPDecomposition
-    # Returns the lower triangular factor +L+
-
-    include Matrix::ConversionHelper
-
-    def l
-      Matrix.build(@row_size, @col_size) do |i, j|
-        if (i > j)
-          @lu[i][j]
-        elsif (i == j)
-          1
-        else
-          0
-        end
-      end
-    end
-
-    # Returns the upper triangular factor +U+
-
-    def u
-      Matrix.build(@col_size, @col_size) do |i, j|
-        if (i <= j)
-          @lu[i][j]
-        else
-          0
-        end
-      end
-    end
-
-    # Returns the permutation matrix +P+
-
-    def p
-      rows = Array.new(@row_size){Array.new(@col_size, 0)}
-      @pivots.each_with_index{|p, i| rows[i][p] = 1}
-      Matrix.send :new, rows, @col_size
-    end
-
-    # Returns +L+, +U+, +P+ in an array
-
-    def to_ary
-      [l, u, p]
-    end
-    alias_method :to_a, :to_ary
-
-    # Returns the pivoting indices
-
-    attr_reader :pivots
-
-    # Returns +true+ if +U+, and hence +A+, is singular.
-
-    def singular? ()
-      @col_size.times do |j|
-        if (@lu[j][j] == 0)
-          return true
-        end
-      end
-      false
-    end
-
-    # Returns the determinant of +A+, calculated efficiently
-    # from the factorization.
-
-    def det
-      if (@row_size != @col_size)
-        Matrix.Raise Matrix::ErrDimensionMismatch unless square?
-      end
-      d = @pivot_sign
-      @col_size.times do |j|
-        d *= @lu[j][j]
-      end
-      d
-    end
-    alias_method :determinant, :det
-
-    # Returns +m+ so that <tt>A*m = b</tt>,
-    # or equivalently so that <tt>L*U*m = P*b</tt>
-    # +b+ can be a Matrix or a Vector
-
-    def solve b
-      if (singular?)
-        Matrix.Raise Matrix::ErrNotRegular, "Matrix is singular."
-      end
-      if b.is_a? Matrix
-        if (b.row_size != @row_size)
-          Matrix.Raise Matrix::ErrDimensionMismatch
-        end
-
-        # Copy right hand side with pivoting
-        nx = b.column_size
-        m = @pivots.map{|row| b.row(row).to_a}
-
-        # Solve L*Y = P*b
-        @col_size.times do |k|
-          (k+1).upto(@col_size-1) do |i|
-            nx.times do |j|
-              m[i][j] -= m[k][j]*@lu[i][k]
-            end
-          end
-        end
-        # Solve U*m = Y
-        (@col_size-1).downto(0) do |k|
-          nx.times do |j|
-            m[k][j] = m[k][j].quo(@lu[k][k])
-          end
-          k.times do |i|
-            nx.times do |j|
-              m[i][j] -= m[k][j]*@lu[i][k]
-            end
-          end
-        end
-        Matrix.send :new, m, nx
-      else # same algorithm, specialized for simpler case of a vector
-        b = convert_to_array(b)
-        if (b.size != @row_size)
-          Matrix.Raise Matrix::ErrDimensionMismatch
-        end
-
-        # Copy right hand side with pivoting
-        m = b.values_at(*@pivots)
-
-        # Solve L*Y = P*b
-        @col_size.times do |k|
-          (k+1).upto(@col_size-1) do |i|
-            m[i] -= m[k]*@lu[i][k]
-          end
-        end
-        # Solve U*m = Y
-        (@col_size-1).downto(0) do |k|
-          m[k] = m[k].quo(@lu[k][k])
-          k.times do |i|
-            m[i] -= m[k]*@lu[i][k]
-          end
-        end
-        Vector.elements(m, false)
-      end
-    end
-
-    def initialize a
-      raise TypeError, "Expected Matrix but got #{a.class}" unless a.is_a?(Matrix)
-      # Use a "left-looking", dot-product, Crout/Doolittle algorithm.
-      @lu = a.to_a
-      @row_size = a.row_size
-      @col_size = a.column_size
-      @pivots = Array.new(@row_size)
-      @row_size.times do |i|
-         @pivots[i] = i
-      end
-      @pivot_sign = 1
-      lu_col_j = Array.new(@row_size)
-
-      # Outer loop.
-
-      @col_size.times do |j|
-
-        # Make a copy of the j-th column to localize references.
-
-        @row_size.times do |i|
-          lu_col_j[i] = @lu[i][j]
-        end
-
-        # Apply previous transformations.
-
-        @row_size.times do |i|
-          lu_row_i = @lu[i]
-
-          # Most of the time is spent in the following dot product.
-
-          kmax = [i, j].min
-          s = 0
-          kmax.times do |k|
-            s += lu_row_i[k]*lu_col_j[k]
-          end
-
-          lu_row_i[j] = lu_col_j[i] -= s
-        end
-
-        # Find pivot and exchange if necessary.
-
-        p = j
-        (j+1).upto(@row_size-1) do |i|
-          if (lu_col_j[i].abs > lu_col_j[p].abs)
-            p = i
-          end
-        end
-        if (p != j)
-          @col_size.times do |k|
-            t = @lu[p][k]; @lu[p][k] = @lu[j][k]; @lu[j][k] = t
-          end
-          k = @pivots[p]; @pivots[p] = @pivots[j]; @pivots[j] = k
-          @pivot_sign = -@pivot_sign
-        end
-
-        # Compute multipliers.
-
-        if (j < @row_size && @lu[j][j] != 0)
-          (j+1).upto(@row_size-1) do |i|
-            @lu[i][j] = @lu[i][j].quo(@lu[j][j])
-          end
-        end
-      end
-    end
-  end
-end
diff --git a/lib/minitest/README.txt b/lib/minitest/README.txt
deleted file mode 100644
index 7b1e6e681f..0000000000
--- a/lib/minitest/README.txt
+++ /dev/null
@@ -1,269 +0,0 @@
-= minitest/*
-
-* http://rubyforge.org/projects/bfts
-
-== DESCRIPTION:
-
-minitest provides a complete suite of testing facilities supporting
-TDD, BDD, mocking, and benchmarking.
-
-minitest/unit is a small and incredibly fast unit testing framework.
-It provides a rich set of assertions to make your tests clean and
-readable.
-
-minitest/spec is a functionally complete spec engine. It hooks onto
-minitest/unit and seamlessly bridges test assertions over to spec
-expectations.
-
-minitest/benchmark is an awesome way to assert the performance of your
-algorithms in a repeatable manner. Now you can assert that your newb
-co-worker doesn't replace your linear algorithm with an exponential
-one!
-
-minitest/mock by Steven Baker, is a beautifully tiny mock object
-framework.
-
-minitest/pride shows pride in testing and adds coloring to your test
-output.
-
-minitest/unit is meant to have a clean implementation for language
-implementors that need a minimal set of methods to bootstrap a working
-test suite. For example, there is no magic involved for test-case
-discovery.
-
-== FEATURES/PROBLEMS:
-
-* minitest/autorun - the easy and explicit way to run all your tests.
-* minitest/unit - a very fast, simple, and clean test system.
-* minitest/spec - a very fast, simple, and clean spec system.
-* minitest/mock - a simple and clean mock system.
-* minitest/benchmark - an awesome way to assert your algorithm's performance.
-* minitest/pride - show your pride in testing!
-* Incredibly small and fast runner, but no bells and whistles.
-
-== RATIONALE:
-
-See design_rationale.rb to see how specs and tests work in minitest.
-
-== SYNOPSIS:
-
-Given that you'd like to test the following class:
-
-  class Meme
-    def i_can_has_cheezburger?
-      "OHAI!"
-    end
-
-    def will_it_blend?
-      "YES!"
-    end
-  end
-
-=== Unit tests
-
-  require 'minitest/autorun'
-
-  class TestMeme < MiniTest::Unit::TestCase
-    def setup
-      @meme = Meme.new
-    end
-
-    def test_that_kitty_can_eat
-      assert_equal "OHAI!", @meme.i_can_has_cheezburger?
-    end
-
-    def test_that_it_will_not_blend
-      refute_match /^no/i, @meme.will_it_blend?
-    end
-  end
-
-=== Specs
-
-  require 'minitest/autorun'
-
-  describe Meme do
-    before do
-      @meme = Meme.new
-    end
-
-    describe "when asked about cheeseburgers" do
-      it "must respond positively" do
-        @meme.i_can_has_cheezburger?.must_equal "OHAI!"
-      end
-    end
-
-    describe "when asked about blending possibilities" do
-      it "won't say no" do
-        @meme.will_it_blend?.wont_match /^no/i
-      end
-    end
-  end
-
-=== Benchmarks
-
-Add benchmarks to your regular unit tests. If the unit tests fail, the
-benchmarks won't run.
-
-  # optionally run benchmarks, good for CI-only work!
-  require 'minitest/benchmark' if ENV["BENCH"]
-
-  class TestMeme < MiniTest::Unit::TestCase
-    # Override self.bench_range or default range is [1, 10, 100, 1_000, 10_000]
-    def bench_my_algorithm
-      assert_performance_linear 0.9999 do |n| # n is a range value
-        n.times do
-          @obj.my_algorithm
-        end
-      end
-    end
-  end
-
-Or add them to your specs. If you make benchmarks optional, you'll
-need to wrap your benchmarks in a conditional since the methods won't
-be defined.
-
-  describe Meme do
-    if ENV["BENCH"] then
-      bench_performance_linear "my_algorithm", 0.9999 do |n|
-        100.times do
-          @obj.my_algorithm(n)
-        end
-      end
-    end
-  end
-
-outputs something like:
-
-  # Running benchmarks:
-
-  TestBlah	100	1000	10000
-  bench_my_algorithm	 0.006167	 0.079279	 0.786993
-  bench_other_algorithm	 0.061679	 0.792797	 7.869932
-
-Output is tab-delimited to make it easy to paste into a spreadsheet.
-
-=== Mocks
-
-  class MemeAsker
-    def initialize(meme)
-      @meme = meme
-    end
-
-    def ask(question)
-      method = question.tr(" ","_") + "?"
-      @meme.send(method)
-    end
-  end
-
-  require 'minitest/autorun'
-
-  describe MemeAsker do
-    before do
-      @meme = MiniTest::Mock.new
-      @meme_asker = MemeAsker.new @meme
-    end
-
-    describe "#ask" do
-      describe "when passed an unpunctuated question" do
-        it "should invoke the appropriate predicate method on the meme" do
-          @meme.expect :will_it_blend?, :return_value
-          @meme_asker.ask "will it blend"
-          @meme.verify
-        end
-      end
-    end
-  end
-
-=== Customizable Test Runner Types:
-
-MiniTest::Unit.runner=(runner) provides an easy way of creating custom
-test runners for specialized needs. Justin Weiss provides the
-following real-world example to create an alternative to regular
-fixture loading:
-
-  class MiniTestWithHooks::Unit < MiniTest::Unit
-    def before_suites
-    end
-
-    def after_suites
-    end
-
-    def _run_suites(suites, type)
-      begin
-        before_suites
-        super(suites, type)
-      ensure
-        after_suites
-      end
-    end
-
-    def _run_suite(suite, type)
-      begin
-        suite.before_suite
-        super(suite, type)
-      ensure
-        suite.after_suite
-      end
-    end
-  end
-
-  module MiniTestWithTransactions
-    class Unit < MiniTestWithHooks::Unit
-      include TestSetupHelper
-
-      def before_suites
-        super
-        setup_nested_transactions
-        # load any data we want available for all tests
-      end
-
-      def after_suites
-        teardown_nested_transactions
-        super
-      end
-    end
-  end
-
-  MiniTest::Unit.runner = MiniTestWithTransactions::Unit.new
-
-== REQUIREMENTS:
-
-* Ruby 1.8, maybe even 1.6 or lower. No magic is involved.
-
-== INSTALL:
-
-  sudo gem install minitest
-
-On 1.9, you already have it. To get newer candy you can still install
-the gem, but you'll need to activate the gem explicitly to use it:
-
-  require 'rubygems'
-  gem 'minitest' # ensures you're using the gem, and not the built in MT
-  require 'minitest/autorun'
-  
-  # ... usual testing stuffs ...
-
-== LICENSE:
-
-(The MIT License)
-
-Copyright (c) Ryan Davis, Seattle.rb
-
-Permission is hereby granted, free of charge, to any person obtaining
-a copy of this software and associated documentation files (the
-'Software'), to deal in the Software without restriction, including
-without limitation the rights to use, copy, modify, merge, publish,
-distribute, sublicense, and/or sell copies of the Software, and to
-permit persons to whom the Software is furnished to do so, subject to
-the following conditions:
-
-The above copyright notice and this permission notice shall be
-included in all copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
-EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
-IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
-CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
-TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
-SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
diff --git a/lib/minitest/autorun.rb b/lib/minitest/autorun.rb
deleted file mode 100644
index 443f2f61d4..0000000000
--- a/lib/minitest/autorun.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-######################################################################
-# This file is imported from the minitest project.
-# DO NOT make modifications in this repo. They _will_ be reverted!
-# File a patch instead and assign it to Ryan Davis.
-######################################################################
-
-begin
-  require 'rubygems'
-  gem 'minitest'
-rescue Gem::LoadError
-  # do nothing
-end
-
-require 'minitest/unit'
-require 'minitest/spec'
-require 'minitest/mock'
-
-MiniTest::Unit.autorun
diff --git a/lib/minitest/benchmark.rb b/lib/minitest/benchmark.rb
deleted file mode 100644
index 77c0afafb7..0000000000
--- a/lib/minitest/benchmark.rb
+++ /dev/null
@@ -1,372 +0,0 @@
-######################################################################
-# This file is imported from the minitest project.
-# DO NOT make modifications in this repo. They _will_ be reverted!
-# File a patch instead and assign it to Ryan Davis.
-######################################################################
-
-require 'minitest/unit'
-require 'minitest/spec'
-
-class MiniTest::Unit
-  attr_accessor :runner
-
-  def run_benchmarks # :nodoc:
-    _run_anything :benchmark
-  end
-
-  def benchmark_suite_header suite # :nodoc:
-    "\n#{suite}\t#{suite.bench_range.join("\t")}"
-  end
-
-  class TestCase
-    ##
-    # Returns a set of ranges stepped exponentially from +min+ to
-    # +max+ by powers of +base+. Eg:
-    #
-    #   bench_exp(2, 16, 2) # => [2, 4, 8, 16]
-
-    def self.bench_exp min, max, base = 10
-      min = (Math.log10(min) / Math.log10(base)).to_i
-      max = (Math.log10(max) / Math.log10(base)).to_i
-
-      (min..max).map { |m| base ** m }.to_a
-    end
-
-    ##
-    # Returns a set of ranges stepped linearly from +min+ to +max+ by
-    # +step+. Eg:
-    #
-    #   bench_linear(20, 40, 10) # => [20, 30, 40]
-
-    def self.bench_linear min, max, step = 10
-      (min..max).step(step).to_a
-    rescue LocalJumpError # 1.8.6
-      r = []; (min..max).step(step) { |n| r << n }; r
-    end
-
-    ##
-    # Returns the benchmark methods (methods that start with bench_)
-    # for that class.
-
-    def self.benchmark_methods # :nodoc:
-      public_instance_methods(true).grep(/^bench_/).map { |m| m.to_s }.sort
-    end
-
-    ##
-    # Returns all test suites that have benchmark methods.
-
-    def self.benchmark_suites
-      TestCase.test_suites.reject { |s| s.benchmark_methods.empty? }
-    end
-
-    ##
-    # Specifies the ranges used for benchmarking for that class.
-    # Defaults to exponential growth from 1 to 10k by powers of 10.
-    # Override if you need different ranges for your benchmarks.
-    #
-    # See also: ::bench_exp and ::bench_linear.
-
-    def self.bench_range
-      bench_exp 1, 10_000
-    end
-
-    ##
-    # Runs the given +work+, gathering the times of each run. Range
-    # and times are then passed to a given +validation+ proc. Outputs
-    # the benchmark name and times in tab-separated format, making it
-    # easy to paste into a spreadsheet for graphing or further
-    # analysis.
-    #
-    # Ranges are specified by ::bench_range.
-    #
-    # Eg:
-    #
-    #   def bench_algorithm
-    #     validation = proc { |x, y| ... }
-    #     assert_performance validation do |x|
-    #       @obj.algorithm
-    #     end
-    #   end
-
-    def assert_performance validation, &work
-      range = self.class.bench_range
-
-      io.print "#{__name__}"
-
-      times = []
-
-      range.each do |x|
-        GC.start
-        t0 = Time.now
-        instance_exec(x, &work)
-        t = Time.now - t0
-
-        io.print "\t%9.6f" % t
-        times << t
-      end
-      io.puts
-
-      validation[range, times]
-    end
-
-    ##
-    # Runs the given +work+ and asserts that the times gathered fit to
-    # match a constant rate (eg, linear slope == 0) within a given
-    # +threshold+. Note: because we're testing for a slope of 0, R^2
-    # is not a good determining factor for the fit, so the threshold
-    # is applied against the slope itself. As such, you probably want
-    # to tighten it from the default.
-    #
-    # See http://www.graphpad.com/curvefit/goodness_of_fit.htm for
-    # more details.
-    #
-    # Fit is calculated by #fit_linear.
-    #
-    # Ranges are specified by ::bench_range.
-    #
-    # Eg:
-    #
-    #   def bench_algorithm
-    #     assert_performance_constant 0.9999 do |x|
-    #       @obj.algorithm
-    #     end
-    #   end
-
-    def assert_performance_constant threshold = 0.99, &work
-      validation = proc do |range, times|
-        a, b, rr = fit_linear range, times
-        assert_in_delta 0, b, 1 - threshold
-        [a, b, rr]
-      end
-
-      assert_performance validation, &work
-    end
-
-    ##
-    # Runs the given +work+ and asserts that the times gathered fit to
-    # match a exponential curve within a given error +threshold+.
-    #
-    # Fit is calculated by #fit_exponential.
-    #
-    # Ranges are specified by ::bench_range.
-    #
-    # Eg:
-    #
-    #   def bench_algorithm
-    #     assert_performance_exponential 0.9999 do |x|
-    #       @obj.algorithm
-    #     end
-    #   end
-
-    def assert_performance_exponential threshold = 0.99, &work
-      assert_performance validation_for_fit(:exponential, threshold), &work
-    end
-
-    ##
-    # Runs the given +work+ and asserts that the times gathered fit to
-    # match a straight line within a given error +threshold+.
-    #
-    # Fit is calculated by #fit_linear.
-    #
-    # Ranges are specified by ::bench_range.
-    #
-    # Eg:
-    #
-    #   def bench_algorithm
-    #     assert_performance_linear 0.9999 do |x|
-    #       @obj.algorithm
-    #     end
-    #   end
-
-    def assert_performance_linear threshold = 0.99, &work
-      assert_performance validation_for_fit(:linear, threshold), &work
-    end
-
-    ##
-    # Runs the given +work+ and asserts that the times gathered curve
-    # fit to match a power curve within a given error +threshold+.
-    #
-    # Fit is calculated by #fit_power.
-    #
-    # Ranges are specified by ::bench_range.
-    #
-    # Eg:
-    #
-    #   def bench_algorithm
-    #     assert_performance_power 0.9999 do |x|
-    #       @obj.algorithm
-    #     end
-    #   end
-
-    def assert_performance_power threshold = 0.99, &work
-      assert_performance validation_for_fit(:power, threshold), &work
-    end
-
-    ##
-    # Takes an array of x/y pairs and calculates the general R^2 value.
-    #
-    # See: http://en.wikipedia.org/wiki/Coefficient_of_determination
-
-    def fit_error xys
-      y_bar  = sigma(xys) { |x, y| y } / xys.size.to_f
-      ss_tot = sigma(xys) { |x, y| (y    - y_bar) ** 2 }
-      ss_err = sigma(xys) { |x, y| (yield(x) - y) ** 2 }
-
-      1 - (ss_err / ss_tot)
-    end
-
-    ##
-    # To fit a functional form: y = ae^(bx).
-    #
-    # Takes x and y values and returns [a, b, r^2].
-    #
-    # See: http://mathworld.wolfram.com/LeastSquaresFittingExponential.html
-
-    def fit_exponential xs, ys
-      n     = xs.size
-      xys   = xs.zip(ys)
-      sxlny = sigma(xys) { |x,y| x * Math.log(y) }
-      slny  = sigma(xys) { |x,y| Math.log(y)     }
-      sx2   = sigma(xys) { |x,y| x * x           }
-      sx    = sigma xs
-
-      c = n * sx2 - sx ** 2
-      a = (slny * sx2 - sx * sxlny) / c
-      b = ( n * sxlny - sx * slny ) / c
-
-      return Math.exp(a), b, fit_error(xys) { |x| Math.exp(a + b * x) }
-    end
-
-    ##
-    # Fits the functional form: a + bx.
-    #
-    # Takes x and y values and returns [a, b, r^2].
-    #
-    # See: http://mathworld.wolfram.com/LeastSquaresFitting.html
-
-    def fit_linear xs, ys
-      n   = xs.size
-      xys = xs.zip(ys)
-      sx  = sigma xs
-      sy  = sigma ys
-      sx2 = sigma(xs)  { |x|   x ** 2 }
-      sxy = sigma(xys) { |x,y| x * y  }
-
-      c = n * sx2 - sx**2
-      a = (sy * sx2 - sx * sxy) / c
-      b = ( n * sxy - sx * sy ) / c
-
-      return a, b, fit_error(xys) { |x| a + b * x }
-    end
-
-    ##
-    # To fit a functional form: y = ax^b.
-    #
-    # Takes x and y values and returns [a, b, r^2].
-    #
-    # See: http://mathworld.wolfram.com/LeastSquaresFittingPowerLaw.html
-
-    def fit_power xs, ys
-      n       = xs.size
-      xys     = xs.zip(ys)
-      slnxlny = sigma(xys) { |x, y| Math.log(x) * Math.log(y) }
-      slnx    = sigma(xs)  { |x   | Math.log(x)               }
-      slny    = sigma(ys)  { |   y| Math.log(y)               }
-      slnx2   = sigma(xs)  { |x   | Math.log(x) ** 2          }
-
-      b = (n * slnxlny - slnx * slny) / (n * slnx2 - slnx ** 2);
-      a = (slny - b * slnx) / n
-
-      return Math.exp(a), b, fit_error(xys) { |x| (Math.exp(a) * (x ** b)) }
-    end
-
-    ##
-    # Enumerates over +enum+ mapping +block+ if given, returning the
-    # sum of the result. Eg:
-    #
-    #   sigma([1, 2, 3])                # => 1 + 2 + 3 => 7
-    #   sigma([1, 2, 3]) { |n| n ** 2 } # => 1 + 4 + 9 => 14
-
-    def sigma enum, &block
-      enum = enum.map(&block) if block
-      enum.inject { |sum, n| sum + n }
-    end
-
-    ##
-    # Returns a proc that calls the specified fit method and asserts
-    # that the error is within a tolerable threshold.
-
-    def validation_for_fit msg, threshold
-      proc do |range, times|
-        a, b, rr = send "fit_#{msg}", range, times
-        assert_operator rr, :>=, threshold
-        [a, b, rr]
-      end
-    end
-  end
-end
-
-class MiniTest::Spec
-  ##
-  # This is used to define a new benchmark method. You usually don't
-  # use this directly and is intended for those needing to write new
-  # performance curve fits (eg: you need a specific polynomial fit).
-  #
-  # See ::bench_performance_linear for an example of how to use this.
-
-  def self.bench name, &block
-    define_method "bench_#{name.gsub(/\W+/, '_')}", &block
-  end
-
-  def self.bench_range &block
-    return super unless block
-
-    meta = (class << self; self; end)
-    meta.send :define_method, "bench_range", &block
-  end
-
-  ##
-  # Create a benchmark that verifies that the performance is linear.
-  #
-  #   describe "my class" do
-  #     bench_performance_linear "fast_algorithm", 0.9999 do
-  #       @obj.fast_algorithm
-  #     end
-  #   end
-
-  def self.bench_performance_linear name, threshold = 0.99, &work
-    bench name do
-      assert_performance_linear threshold, &work
-    end
-  end
-
-  ##
-  # Create a benchmark that verifies that the performance is constant.
-  #
-  #   describe "my class" do
-  #     bench_performance_constant "zoom_algorithm!" do
-  #       @obj.zoom_algorithm!
-  #     end
-  #   end
-
-  def self.bench_performance_constant name, threshold = 0.99, &work
-    bench name do
-      assert_performance_constant threshold, &work
-    end
-  end
-
-  ##
-  # Create a benchmark that verifies that the performance is exponential.
-  #
-  #   describe "my class" do
-  #     bench_performance_exponential "algorithm" do
-  #       @obj.algorithm
-  #     end
-  #   end
-
-  def self.bench_performance_exponential name, threshold = 0.99, &work
-    bench name do
-      assert_performance_exponential threshold, &work
-    end
-  end
-end
diff --git a/lib/minitest/mock.rb b/lib/minitest/mock.rb
deleted file mode 100644
index c342c04995..0000000000
--- a/lib/minitest/mock.rb
+++ /dev/null
@@ -1,106 +0,0 @@
-######################################################################
-# This file is imported from the minitest project.
-# DO NOT make modifications in this repo. They _will_ be reverted!
-# File a patch instead and assign it to Ryan Davis.
-######################################################################
-
-class MockExpectationError < StandardError; end
-
-##
-# A simple and clean mock object framework.
-
-module MiniTest
-
-  ##
-  # All mock objects are an instance of Mock
-
-  class Mock
-    alias :__respond_to? :respond_to?
-
-    skip_methods = %w(object_id respond_to_missing? inspect === to_s)
-
-    instance_methods.each do |m|
-      undef_method m unless skip_methods.include?(m.to_s) || m =~ /^__/
-    end
-
-    def initialize # :nodoc:
-      @expected_calls = {}
-      @actual_calls = Hash.new {|h,k| h[k] = [] }
-    end
-
-    ##
-    # Expect that method +name+ is called, optionally with +args+, and returns
-    # +retval+.
-    #
-    #   @mock.expect(:meaning_of_life, 42)
-    #   @mock.meaning_of_life # => 42
-    #
-    #   @mock.expect(:do_something_with, true, [some_obj, true])
-    #   @mock.do_something_with(some_obj, true) # => true
-    #
-    # +args+ is compared to the expected args using case equality (ie, the
-    # '===' operator), allowing for less specific expectations.
-    #
-    #   @mock.expect(:uses_any_string, true, [String])
-    #   @mock.uses_any_string("foo") # => true
-    #   @mock.verify  # => true
-    #
-    #   @mock.expect(:uses_one_string, true, ["foo"]
-    #   @mock.uses_one_string("bar") # => true
-    #   @mock.verify  # => raises MockExpectationError
-
-    def expect(name, retval, args=[])
-      @expected_calls[name] = { :retval => retval, :args => args }
-      self
-    end
-
-    ##
-    # Verify that all methods were called as expected. Raises
-    # +MockExpectationError+ if the mock object was not called as
-    # expected.
-
-    def verify
-      @expected_calls.each_key do |name|
-        expected = @expected_calls[name]
-        msg1 = "expected #{name}, #{expected.inspect}"
-        msg2 = "#{msg1}, got #{@actual_calls[name].inspect}"
-
-        raise MockExpectationError, msg2 if
-          @actual_calls.has_key? name and
-          not @actual_calls[name].include?(expected)
-
-        raise MockExpectationError, msg1 unless
-          @actual_calls.has_key? name and @actual_calls[name].include?(expected)
-      end
-      true
-    end
-
-    def method_missing(sym, *args) # :nodoc:
-      expected = @expected_calls[sym]
-
-      unless expected then
-        raise NoMethodError, "unmocked method %p, expected one of %p" %
-          [sym, @expected_calls.keys.sort_by(&:to_s)]
-      end
-
-      expected_args, retval = expected[:args], expected[:retval]
-
-      unless expected_args.size == args.size
-        raise ArgumentError, "mocked method %p expects %d arguments, got %d" %
-          [sym, expected[:args].size, args.size]
-      end
-
-      @actual_calls[sym] << {
-        :retval => retval,
-        :args => expected_args.zip(args).map { |mod, a| mod if mod === a }
-      }
-
-      retval
-    end
-
-    def respond_to?(sym) # :nodoc:
-      return true if @expected_calls.has_key?(sym)
-      return __respond_to?(sym)
-    end
-  end
-end
diff --git a/lib/minitest/pride.rb b/lib/minitest/pride.rb
deleted file mode 100644
index ac7745695c..0000000000
--- a/lib/minitest/pride.rb
+++ /dev/null
@@ -1,99 +0,0 @@
-######################################################################
-# This file is imported from the minitest project.
-# DO NOT make modifications in this repo. They _will_ be reverted!
-# File a patch instead and assign it to Ryan Davis.
-######################################################################
-
-require "minitest/unit"
-
-##
-# Show your testing pride!
-
-class PrideIO
-  ESC = "\e["
-  NND = "#{ESC}0m"
-
-  attr_reader :io
-
-  def initialize io
-    @io = io
-    # stolen from /System/Library/Perl/5.10.0/Term/ANSIColor.pm
-    # also reference http://en.wikipedia.org/wiki/ANSI_escape_code
-    @colors ||= (31..36).to_a
-    @size   = @colors.size
-    @index  = 0
-    # io.sync = true
-  end
-
-  def print o
-    case o
-    when "." then
-      io.print pride o
-    when "E", "F" then
-      io.print "#{ESC}41m#{ESC}37m#{o}#{NND}"
-    else
-      io.print o
-    end
-  end
-
-  def puts(*o)
-    o.map! { |s|
-      s.sub(/Finished tests/) {
-        @index = 0
-        'Fabulous tests'.split(//).map { |c|
-          pride(c)
-        }.join
-      }
-    }
-
-    super
-  end
-
-  def pride string
-    string = "*" if string == "."
-    c = @colors[@index % @size]
-    @index += 1
-    "#{ESC}#{c}m#{string}#{NND}"
-  end
-
-  def method_missing msg, *args
-    io.send(msg, *args)
-  end
-end
-
-class PrideLOL < PrideIO # inspired by lolcat, but massively cleaned up
-  PI_3 = Math::PI / 3
-
-  def initialize io
-    # walk red, green, and blue around a circle separated by equal thirds.
-    #
-    # To visualize, type this into wolfram-alpha:
-    #
-    #   plot (3*sin(x)+3), (3*sin(x+2*pi/3)+3), (3*sin(x+4*pi/3)+3)
-
-    # 6 has wide pretty gradients. 3 == lolcat, about half the width
-    @colors = (0...(6 * 7)).map { |n|
-      n *= 1.0 / 6
-      r  = (3 * Math.sin(n           ) + 3).to_i
-      g  = (3 * Math.sin(n + 2 * PI_3) + 3).to_i
-      b  = (3 * Math.sin(n + 4 * PI_3) + 3).to_i
-
-      # Then we take rgb and encode them in a single number using base 6.
-      # For some mysterious reason, we add 16... to clear the bottom 4 bits?
-      # Yes... they're ugly.
-
-      36 * r + 6 * g + b + 16
-    }
-
-    super
-  end
-
-  def pride string
-    c = @colors[@index % @size]
-    @index += 1
-    "#{ESC}38;5;#{c}m#{string}#{NND}"
-  end
-end
-
-klass = ENV['TERM'] =~ /^xterm(-256color)?$/ ? PrideLOL : PrideIO
-MiniTest::Unit.output = klass.new(MiniTest::Unit.output)
diff --git a/lib/minitest/spec.rb b/lib/minitest/spec.rb
deleted file mode 100644
index a70bbdd405..0000000000
--- a/lib/minitest/spec.rb
+++ /dev/null
@@ -1,519 +0,0 @@
-######################################################################
-# This file is imported from the minitest project.
-# DO NOT make modifications in this repo. They _will_ be reverted!
-# File a patch instead and assign it to Ryan Davis.
-######################################################################
-
-#!/usr/bin/ruby -w
-
-require 'minitest/unit'
-
-class Module # :nodoc:
-  def infect_an_assertion meth, new_name, dont_flip = false # :nodoc:
-    # warn "%-22p -> %p %p" % [meth, new_name, dont_flip]
-    self.class_eval <<-EOM
-      def #{new_name} *args, &block
-        return MiniTest::Spec.current.#{meth}(*args, &self) if
-          Proc === self
-        return MiniTest::Spec.current.#{meth}(args.first, self) if
-          args.size == 1 unless #{!!dont_flip}
-        return MiniTest::Spec.current.#{meth}(self, *args)
-      end
-    EOM
-  end
-
-  ##
-  # infect_with_assertions has been removed due to excessive clever.
-  # Use infect_an_assertion directly instead.
-
-  def infect_with_assertions(pos_prefix, neg_prefix,
-                             skip_re,
-                             dont_flip_re = /\c0/,
-                             map = {})
-    abort "infect_with_assertions is dead. Use infect_an_assertion directly"
-  end
-end
-
-module Kernel # :nodoc:
-  ##
-  # Describe a series of expectations for a given target +desc+.
-  #
-  # TODO: find good tutorial url.
-  #
-  # Defines a test class subclassing from either MiniTest::Spec or
-  # from the surrounding describe's class. The surrounding class may
-  # subclass MiniTest::Spec manually in order to easily share code:
-  #
-  #     class MySpec < MiniTest::Spec
-  #       # ... shared code ...
-  #     end
-  #
-  #     class TestStuff < MySpec
-  #       it "does stuff" do
-  #         # shared code available here
-  #       end
-  #       describe "inner stuff" do
-  #         it "still does stuff" do
-  #           # ...and here
-  #         end
-  #       end
-  #     end
-
-  def describe desc, additional_desc = nil, &block # :doc:
-    stack = MiniTest::Spec.describe_stack
-    name  = [stack.last, desc, additional_desc].compact.join("::")
-    sclas = stack.last || if Class === self && self < MiniTest::Spec then
-                            self
-                          else
-                            MiniTest::Spec.spec_type desc
-                          end
-
-    cls = sclas.create name, desc
-
-    stack.push cls
-    cls.class_eval(&block)
-    stack.pop
-    cls
-  end
-  private :describe
-end
-
-##
-# MiniTest::Spec -- The faster, better, less-magical spec framework!
-#
-# For a list of expectations, see MiniTest::Expectations.
-
-class MiniTest::Spec < MiniTest::Unit::TestCase
-  ##
-  # Contains pairs of matchers and Spec classes to be used to
-  # calculate the superclass of a top-level describe. This allows for
-  # automatically customizable spec types.
-  #
-  # See: register_spec_type and spec_type
-
-  TYPES = [[//, MiniTest::Spec]]
-
-  ##
-  # Register a new type of spec that matches the spec's description.
-  # This method can take either a Regexp and a spec class or a spec
-  # class and a block that takes the description and returns true if
-  # it matches.
-  #
-  # Eg:
-  #
-  #     register_spec_type(/Controller$/, MiniTest::Spec::Rails)
-  #
-  # or:
-  #
-  #     register_spec_type(MiniTest::Spec::RailsModel) do |desc|
-  #       desc.superclass == ActiveRecord::Base
-  #     end
-
-  def self.register_spec_type(*args, &block)
-    if block then
-      matcher, klass = block, args.first
-    else
-      matcher, klass = *args
-    end
-    TYPES.unshift [matcher, klass]
-  end
-
-  ##
-  # Figure out the spec class to use based on a spec's description. Eg:
-  #
-  #     spec_type("BlahController") # => MiniTest::Spec::Rails
-
-  def self.spec_type desc
-    TYPES.find { |matcher, klass|
-      if matcher.respond_to? :call then
-        matcher.call desc
-      else
-        matcher === desc.to_s
-      end
-    }.last
-  end
-
-  @@describe_stack = []
-  def self.describe_stack # :nodoc:
-    @@describe_stack
-  end
-
-  def self.current # :nodoc:
-    @@current_spec
-  end
-
-  ##
-  # Returns the children of this spec.
-
-  def self.children
-    @children ||= []
-  end
-
-  def initialize name # :nodoc:
-    super
-    @@current_spec = self
-  end
-
-  def self.nuke_test_methods! # :nodoc:
-    self.public_instance_methods.grep(/^test_/).each do |name|
-      self.send :undef_method, name
-    end
-  end
-
-  ##
-  # Define a 'before' action. Inherits the way normal methods should.
-  #
-  # NOTE: +type+ is ignored and is only there to make porting easier.
-  #
-  # Equivalent to MiniTest::Unit::TestCase#setup.
-
-  def self.before type = :each, &block
-    raise "unsupported before type: #{type}" unless type == :each
-
-    add_setup_hook {|tc| tc.instance_eval(&block) }
-  end
-
-  ##
-  # Define an 'after' action. Inherits the way normal methods should.
-  #
-  # NOTE: +type+ is ignored and is only there to make porting easier.
-  #
-  # Equivalent to MiniTest::Unit::TestCase#teardown.
-
-  def self.after type = :each, &block
-    raise "unsupported after type: #{type}" unless type == :each
-
-    add_teardown_hook {|tc| tc.instance_eval(&block) }
-  end
-
-  ##
-  # Define an expectation with name +desc+. Name gets morphed to a
-  # proper test method name. For some freakish reason, people who
-  # write specs don't like class inheritence, so this goes way out of
-  # its way to make sure that expectations aren't inherited.
-  #
-  # Hint: If you _do_ want inheritence, use minitest/unit. You can mix
-  # and match between assertions and expectations as much as you want.
-
-  def self.it desc, &block
-    block ||= proc { skip "(no tests defined)" }
-
-    @specs ||= 0
-    @specs += 1
-
-    name = "test_%04d_%s" % [ @specs, desc.gsub(/\W+/, '_').downcase ]
-
-    define_method name, &block
-
-    self.children.each do |mod|
-      mod.send :undef_method, name if mod.public_method_defined? name
-    end
-  end
-
-  def self.let name, &block
-    define_method name do
-      @_memoized ||= {}
-      @_memoized.fetch(name) { |k| @_memoized[k] = instance_eval(&block) }
-    end
-  end
-
-  def self.subject &block
-    let :subject, &block
-  end
-
-  def self.create name, desc # :nodoc:
-    cls = Class.new(self) do
-      @name = name
-      @desc = desc
-
-      nuke_test_methods!
-    end
-
-    children << cls
-
-    cls
-  end
-
-  def self.to_s # :nodoc:
-    defined?(@name) ? @name : super
-  end
-
-  # :stopdoc:
-  class << self
-    attr_reader :name, :desc
-  end
-  # :startdoc:
-end
-
-module MiniTest::Expectations
-  ##
-  # See MiniTest::Assertions#assert_empty.
-  #
-  #    collection.must_be_empty
-  #
-  # :method: must_be_empty
-
-  infect_an_assertion :assert_empty, :must_be_empty
-
-  ##
-  # See MiniTest::Assertions#assert_equal
-  #
-  #    a.must_equal b
-  #
-  # :method: must_equal
-
-  infect_an_assertion :assert_equal, :must_equal
-
-  ##
-  # See MiniTest::Assertions#assert_in_delta
-  #
-  #    n.must_be_close_to m [, delta]
-  #
-  # :method: must_be_within_delta
-
-  infect_an_assertion :assert_in_delta, :must_be_close_to
-
-  alias :must_be_within_delta :must_be_close_to
-
-  ##
-  # See MiniTest::Assertions#assert_in_epsilon
-  #
-  #    n.must_be_within_epsilon m [, epsilon]
-  #
-  # :method: must_be_within_epsilon
-
-  infect_an_assertion :assert_in_epsilon, :must_be_within_epsilon
-
-  ##
-  # See MiniTest::Assertions#assert_includes
-  #
-  #    collection.must_include obj
-  #
-  # :method: must_include
-
-  infect_an_assertion :assert_includes, :must_include, :reverse
-
-  ##
-  # See MiniTest::Assertions#assert_instance_of
-  #
-  #    obj.must_be_instance_of klass
-  #
-  # :method: must_be_instance_of
-
-  infect_an_assertion :assert_instance_of, :must_be_instance_of
-
-  ##
-  # See MiniTest::Assertions#assert_kind_of
-  #
-  #    obj.must_be_kind_of mod
-  #
-  # :method: must_be_kind_of
-
-  infect_an_assertion :assert_kind_of, :must_be_kind_of
-
-  ##
-  # See MiniTest::Assertions#assert_match
-  #
-  #    a.must_match b
-  #
-  # :method: must_match
-
-  infect_an_assertion :assert_match, :must_match
-
-  ##
-  # See MiniTest::Assertions#assert_nil
-  #
-  #    obj.must_be_nil
-  #
-  # :method: must_be_nil
-
-  infect_an_assertion :assert_nil, :must_be_nil
-
-  ##
-  # See MiniTest::Assertions#assert_operator
-  #
-  #    n.must_be :<=, 42
-  #
-  # :method: must_be
-
-  infect_an_assertion :assert_operator, :must_be
-
-  ##
-  # See MiniTest::Assertions#assert_output
-  #
-  #    proc { ... }.must_output out_or_nil [, err]
-  #
-  # :method: must_output
-
-  infect_an_assertion :assert_output, :must_output
-
-  ##
-  # See MiniTest::Assertions#assert_raises
-  #
-  #    proc { ... }.must_raise exception
-  #
-  # :method: must_raise
-
-  infect_an_assertion :assert_raises, :must_raise
-
-  ##
-  # See MiniTest::Assertions#assert_respond_to
-  #
-  #    obj.must_respond_to msg
-  #
-  # :method: must_respond_to
-
-  infect_an_assertion :assert_respond_to, :must_respond_to, :reverse
-
-  ##
-  # See MiniTest::Assertions#assert_same
-  #
-  #    a.must_be_same_as b
-  #
-  # :method: must_be_same_as
-
-  infect_an_assertion :assert_same, :must_be_same_as
-
-  ##
-  # See MiniTest::Assertions#assert_send
-  # TODO: remove me
-  #
-  #    a.must_send
-  #
-  # :method: must_send
-
-  infect_an_assertion :assert_send, :must_send
-
-  ##
-  # See MiniTest::Assertions#assert_silent
-  #
-  #    proc { ... }.must_be_silent
-  #
-  # :method: must_be_silent
-
-  infect_an_assertion :assert_silent, :must_be_silent
-
-  ##
-  # See MiniTest::Assertions#assert_throws
-  #
-  #    proc { ... }.must_throw sym
-  #
-  # :method: must_throw
-
-  infect_an_assertion :assert_throws, :must_throw
-
-  ##
-  # See MiniTest::Assertions#refute_empty
-  #
-  #    collection.wont_be_empty
-  #
-  # :method: wont_be_empty
-
-  infect_an_assertion :refute_empty, :wont_be_empty
-
-  ##
-  # See MiniTest::Assertions#refute_equal
-  #
-  #    a.wont_equal b
-  #
-  # :method: wont_equal
-
-  infect_an_assertion :refute_equal, :wont_equal
-
-  ##
-  # See MiniTest::Assertions#refute_in_delta
-  #
-  #    n.wont_be_close_to m [, delta]
-  #
-  # :method: wont_be_within_delta
-
-  infect_an_assertion :refute_in_delta, :wont_be_within_delta
-
-  alias :wont_be_close_to :wont_be_within_delta
-  # FIX: reverse aliases
-
-  ##
-  # See MiniTest::Assertions#refute_in_epsilon
-  #
-  #    n.wont_be_within_epsilon m [, epsilon]
-  #
-  # :method: wont_be_within_epsilon
-
-  infect_an_assertion :refute_in_epsilon, :wont_be_within_epsilon
-
-  ##
-  # See MiniTest::Assertions#refute_includes
-  #
-  #    collection.wont_include obj
-  #
-  # :method: wont_include
-
-  infect_an_assertion :refute_includes, :wont_include, :reverse
-
-  ##
-  # See MiniTest::Assertions#refute_instance_of
-  #
-  #    obj.wont_be_instance_of klass
-  #
-  # :method: wont_be_instance_of
-
-  infect_an_assertion :refute_instance_of, :wont_be_instance_of
-
-  ##
-  # See MiniTest::Assertions#refute_kind_of
-  #
-  #    obj.wont_be_kind_of mod
-  #
-  # :method: wont_be_kind_of
-
-  infect_an_assertion :refute_kind_of, :wont_be_kind_of
-
-  ##
-  # See MiniTest::Assertions#refute_match
-  #
-  #    a.wont_match b
-  #
-  # :method: wont_match
-
-  infect_an_assertion :refute_match, :wont_match
-
-  ##
-  # See MiniTest::Assertions#refute_nil
-  #
-  #    obj.wont_be_nil
-  #
-  # :method: wont_be_nil
-
-  infect_an_assertion :refute_nil, :wont_be_nil
-
-  ##
-  # See MiniTest::Assertions#refute_operator
-  #
-  #    n.wont_be :<=, 42
-  #
-  # :method: wont_be
-
-  infect_an_assertion :refute_operator, :wont_be
-
-  ##
-  # See MiniTest::Assertions#refute_respond_to
-  #
-  #    obj.wont_respond_to msg
-  #
-  # :method: wont_respond_to
-
-  infect_an_assertion :refute_respond_to, :wont_respond_to, :reverse
-
-  ##
-  # See MiniTest::Assertions#refute_same
-  #
-  #    a.wont_be_same_as b
-  #
-  # :method: wont_be_same_as
-
-  infect_an_assertion :refute_same, :wont_be_same_as
-end
-
-class Object
-  include MiniTest::Expectations
-end
diff --git a/lib/minitest/unit.rb b/lib/minitest/unit.rb
deleted file mode 100644
index 922ef70183..0000000000
--- a/lib/minitest/unit.rb
+++ /dev/null
@@ -1,1169 +0,0 @@
-######################################################################
-# This file is imported from the minitest project.
-# DO NOT make modifications in this repo. They _will_ be reverted!
-# File a patch instead and assign it to Ryan Davis.
-######################################################################
-
-require 'optparse'
-require 'rbconfig'
-
-##
-# Minimal (mostly drop-in) replacement for test-unit.
-#
-# :include: README.txt
-
-module MiniTest
-
-  ##
-  # Assertion base class
-
-  class Assertion < Exception; end
-
-  ##
-  # Assertion raised when skipping a test
-
-  class Skip < Assertion; end
-
-  file = if RUBY_VERSION =~ /^1\.9/ then  # bt's expanded, but __FILE__ isn't :(
-           File.expand_path __FILE__
-         elsif  __FILE__ =~ /^[^\.]/ then # assume both relative
-           require 'pathname'
-           pwd = Pathname.new Dir.pwd
-           pn = Pathname.new File.expand_path(__FILE__)
-           relpath = pn.relative_path_from(pwd) rescue pn
-           pn = File.join ".", relpath unless pn.relative?
-           pn.to_s
-         else                             # assume both are expanded
-           __FILE__
-         end
-
-  # './lib' in project dir, or '/usr/local/blahblah' if installed
-  MINI_DIR = File.dirname(File.dirname(file)) # :nodoc:
-
-  def self.filter_backtrace bt # :nodoc:
-    return ["No backtrace"] unless bt
-
-    new_bt = []
-
-    unless $DEBUG then
-      bt.each do |line|
-        break if line.rindex MINI_DIR, 0
-        new_bt << line
-      end
-
-      new_bt = bt.reject { |line| line.rindex MINI_DIR, 0 } if new_bt.empty?
-      new_bt = bt.dup if new_bt.empty?
-    else
-      new_bt = bt.dup
-    end
-
-    new_bt
-  end
-
-  ##
-  # MiniTest Assertions.  All assertion methods accept a +msg+ which is
-  # printed if the assertion fails.
-
-  module Assertions
-
-    WINDOZE = RbConfig::CONFIG['host_os'] =~ /mswin|mingw/
-
-    ##
-    # Returns the diff command to use in #diff. Tries to intelligently
-    # figure out what diff to use.
-
-    def self.diff
-      @diff = if WINDOZE
-                "diff.exe -u"
-              else
-                if system("gdiff", __FILE__, __FILE__)
-                  "gdiff -u" # solaris and kin suck
-                elsif system("diff", __FILE__, __FILE__)
-                  "diff -u"
-                else
-                  nil
-                end
-              end unless defined? @diff
-
-      @diff
-    end
-
-    ##
-    # Set the diff command to use in #diff.
-
-    def self.diff= o
-      @diff = o
-    end
-
-    ##
-    # Returns a diff between +exp+ and +act+. If there is no known
-    # diff command or if it doesn't make sense to diff the output
-    # (single line, short output), then it simply returns a basic
-    # comparison between the two.
-
-    def diff exp, act
-      require "tempfile"
-
-      expect = mu_pp_for_diff exp
-      butwas = mu_pp_for_diff act
-      result = nil
-
-      need_to_diff =
-        MiniTest::Assertions.diff &&
-        (expect.include?("\n")    ||
-         butwas.include?("\n")    ||
-         expect.size > 30         ||
-         butwas.size > 30         ||
-         expect == butwas)
-
-      return "Expected: #{mu_pp exp}\n  Actual: #{mu_pp act}" unless
-        need_to_diff
-
-      Tempfile.open("expect") do |a|
-        a.puts expect
-        a.flush
-
-        Tempfile.open("butwas") do |b|
-          b.puts butwas
-          b.flush
-
-          result = `#{MiniTest::Assertions.diff} #{a.path} #{b.path}`
-          result.sub!(/^\-\-\- .+/, "--- expected")
-          result.sub!(/^\+\+\+ .+/, "+++ actual")
-
-          if result.empty? then
-            klass = exp.class
-            result = [
-                      "No visible difference.",
-                      "You should look at your implementation of #{klass}#==.",
-                      expect
-                     ].join "\n"
-          end
-        end
-      end
-
-      result
-    end
-
-    ##
-    # This returns a human-readable version of +obj+. By default
-    # #inspect is called. You can override this to use #pretty_print
-    # if you want.
-
-    def mu_pp obj
-      s = obj.inspect
-      s = s.encode Encoding.default_external if defined? Encoding
-      s
-    end
-
-    ##
-    # This returns a diff-able human-readable version of +obj+. This
-    # differs from the regular mu_pp because it expands escaped
-    # newlines and makes hex-values generic (like object_ids). This
-    # uses mu_pp to do the first pass and then cleans it up.
-
-    def mu_pp_for_diff obj # TODO: possibly rename
-      mu_pp(obj).gsub(/\\n/, "\n").gsub(/0x[a-f0-9]+/m, '0xXXXXXX')
-    end
-
-    def _assertions= n # :nodoc:
-      @_assertions = n
-    end
-
-    def _assertions # :nodoc:
-      @_assertions ||= 0
-    end
-
-    ##
-    # Fails unless +test+ is a true value.
-
-    def assert test, msg = nil
-      msg ||= "Failed assertion, no message given."
-      self._assertions += 1
-      unless test then
-        msg = msg.call if Proc === msg
-        raise MiniTest::Assertion, msg
-      end
-      true
-    end
-
-    ##
-    # Fails unless the block returns a true value.
-
-    def assert_block msg = nil
-      msg = message(msg) { "Expected block to return true value" }
-      assert yield, msg
-    end
-
-    ##
-    # Fails unless +obj+ is empty.
-
-    def assert_empty obj, msg = nil
-      msg = message(msg) { "Expected #{mu_pp(obj)} to be empty" }
-      assert_respond_to obj, :empty?
-      assert obj.empty?, msg
-    end
-
-    ##
-    # Fails unless <tt>exp == act</tt> printing the difference between
-    # the two, if possible.
-    #
-    # If there is no visible difference but the assertion fails, you
-    # should suspect that your #== is buggy, or your inspect output is
-    # missing crucial details.
-    #
-    # For floats use assert_in_delta.
-    #
-    # See also: MiniTest::Assertions.diff
-
-    def assert_equal exp, act, msg = nil
-      msg = message(msg, "") { diff exp, act }
-      assert(exp == act, msg)
-    end
-
-    ##
-    # For comparing Floats.  Fails unless +exp+ and +act+ are within +delta+
-    # of each other.
-    #
-    #   assert_in_delta Math::PI, (22.0 / 7.0), 0.01
-
-    def assert_in_delta exp, act, delta = 0.001, msg = nil
-      n = (exp - act).abs
-      msg = message(msg) { "Expected #{exp} - #{act} (#{n}) to be < #{delta}" }
-      assert delta >= n, msg
-    end
-
-    ##
-    # For comparing Floats.  Fails unless +exp+ and +act+ have a relative
-    # error less than +epsilon+.
-
-    def assert_in_epsilon a, b, epsilon = 0.001, msg = nil
-      assert_in_delta a, b, [a, b].min * epsilon, msg
-    end
-
-    ##
-    # Fails unless +collection+ includes +obj+.
-
-    def assert_includes collection, obj, msg = nil
-      msg = message(msg) {
-        "Expected #{mu_pp(collection)} to include #{mu_pp(obj)}"
-      }
-      assert_respond_to collection, :include?
-      assert collection.include?(obj), msg
-    end
-
-    ##
-    # Fails unless +obj+ is an instace of +cls+.
-
-    def assert_instance_of cls, obj, msg = nil
-      msg = message(msg) {
-        "Expected #{mu_pp(obj)} to be an instance of #{cls}, not #{obj.class}"
-      }
-
-      assert obj.instance_of?(cls), msg
-    end
-
-    ##
-    # Fails unless +obj+ is a kind of +cls+.
-
-    def assert_kind_of cls, obj, msg = nil # TODO: merge with instance_of
-      msg = message(msg) {
-        "Expected #{mu_pp(obj)} to be a kind of #{cls}, not #{obj.class}" }
-
-      assert obj.kind_of?(cls), msg
-    end
-
-    ##
-    # Fails unless +exp+ is <tt>=~</tt> +act+.
-
-    def assert_match exp, act, msg = nil
-      msg = message(msg) { "Expected #{mu_pp(exp)} to match #{mu_pp(act)}" }
-      assert_respond_to act, :"=~"
-      exp = Regexp.new Regexp.escape exp if String === exp and String === act
-      assert exp =~ act, msg
-    end
-
-    ##
-    # Fails unless +obj+ is nil
-
-    def assert_nil obj, msg = nil
-      msg = message(msg) { "Expected #{mu_pp(obj)} to be nil" }
-      assert obj.nil?, msg
-    end
-
-    ##
-    # For testing equality operators and so-forth.
-    #
-    #   assert_operator 5, :<=, 4
-
-    def assert_operator o1, op, o2, msg = nil
-      msg = message(msg) { "Expected #{mu_pp(o1)} to be #{op} #{mu_pp(o2)}" }
-      assert o1.__send__(op, o2), msg
-    end
-
-    ##
-    # Fails if stdout or stderr do not output the expected results.
-    # Pass in nil if you don't care about that streams output. Pass in
-    # "" if you require it to be silent.
-    #
-    # See also: #assert_silent
-
-    def assert_output stdout = nil, stderr = nil
-      out, err = capture_io do
-        yield
-      end
-
-      x = assert_equal stdout, out, "In stdout" if stdout
-      y = assert_equal stderr, err, "In stderr" if stderr
-
-      (!stdout || x) && (!stderr || y)
-    end
-
-    ##
-    # Fails unless the block raises one of +exp+
-
-    def assert_raises *exp
-      msg = "#{exp.pop}\n" if String === exp.last
-
-      should_raise = false
-      begin
-        yield
-        should_raise = true
-      rescue MiniTest::Skip => e
-        details = "#{msg}#{mu_pp(exp)} exception expected, not"
-
-        if exp.include? MiniTest::Skip then
-          return e
-        else
-          raise e
-        end
-      rescue Exception => e
-        details = "#{msg}#{mu_pp(exp)} exception expected, not"
-        assert(exp.any? { |ex|
-                 ex.instance_of?(Module) ? e.kind_of?(ex) : ex == e.class
-               }, exception_details(e, details))
-
-        return e
-      end
-
-      exp = exp.first if exp.size == 1
-      flunk "#{msg}#{mu_pp(exp)} expected but nothing was raised." if
-        should_raise
-    end
-
-    ##
-    # Fails unless +obj+ responds to +meth+.
-
-    def assert_respond_to obj, meth, msg = nil
-      msg = message(msg) {
-        "Expected #{mu_pp(obj)} (#{obj.class}) to respond to ##{meth}"
-      }
-      assert obj.respond_to?(meth), msg
-    end
-
-    ##
-    # Fails unless +exp+ and +act+ are #equal?
-
-    def assert_same exp, act, msg = nil
-      msg = message(msg) {
-        data = [mu_pp(act), act.object_id, mu_pp(exp), exp.object_id]
-        "Expected %s (oid=%d) to be the same as %s (oid=%d)" % data
-      }
-      assert exp.equal?(act), msg
-    end
-
-    ##
-    # +send_ary+ is a receiver, message and arguments.
-    #
-    # Fails unless the call returns a true value
-    # TODO: I should prolly remove this from specs
-
-    def assert_send send_ary, m = nil
-      recv, msg, *args = send_ary
-      m = message(m) {
-        "Expected #{mu_pp(recv)}.#{msg}(*#{mu_pp(args)}) to return true" }
-      assert recv.__send__(msg, *args), m
-    end
-
-    ##
-    # Fails if the block outputs anything to stderr or stdout.
-    #
-    # See also: #assert_output
-
-    def assert_silent
-      assert_output "", "" do
-        yield
-      end
-    end
-
-    ##
-    # Fails unless the block throws +sym+
-
-    def assert_throws sym, msg = nil
-      default = "Expected #{mu_pp(sym)} to have been thrown"
-      caught = true
-      catch(sym) do
-        begin
-          yield
-        rescue ArgumentError => e     # 1.9 exception
-          default += ", not #{e.message.split(/ /).last}"
-        rescue NameError => e         # 1.8 exception
-          default += ", not #{e.name.inspect}"
-        end
-        caught = false
-      end
-
-      assert caught, message(msg) { default }
-    end
-
-    ##
-    # Captures $stdout and $stderr into strings:
-    #
-    #   out, err = capture_io do
-    #     warn "You did a bad thing"
-    #   end
-    #
-    #   assert_match %r%bad%, err
-
-    def capture_io
-      require 'stringio'
-
-      orig_stdout, orig_stderr         = $stdout, $stderr
-      captured_stdout, captured_stderr = StringIO.new, StringIO.new
-      $stdout, $stderr                 = captured_stdout, captured_stderr
-
-      yield
-
-      return captured_stdout.string, captured_stderr.string
-    ensure
-      $stdout = orig_stdout
-      $stderr = orig_stderr
-    end
-
-    ##
-    # Returns details for exception +e+
-
-    def exception_details e, msg
-      [
-       "#{msg}",
-       "Class: <#{e.class}>",
-       "Message: <#{e.message.inspect}>",
-       "---Backtrace---",
-       "#{MiniTest::filter_backtrace(e.backtrace).join("\n")}",
-       "---------------",
-      ].join "\n"
-    end
-
-    ##
-    # Fails with +msg+
-
-    def flunk msg = nil
-      msg ||= "Epic Fail!"
-      assert false, msg
-    end
-
-    ##
-    # Returns a proc that will output +msg+ along with the default message.
-
-    def message msg = nil, ending = ".", &default
-      proc {
-        custom_message = "#{msg}.\n" unless msg.nil? or msg.to_s.empty?
-        "#{custom_message}#{default.call}#{ending}"
-      }
-    end
-
-    ##
-    # used for counting assertions
-
-    def pass msg = nil
-      assert true
-    end
-
-    ##
-    # Fails if +test+ is a true value
-
-    def refute test, msg = nil
-      msg ||= "Failed refutation, no message given"
-      not assert(! test, msg)
-    end
-
-    ##
-    # Fails if +obj+ is empty.
-
-    def refute_empty obj, msg = nil
-      msg = message(msg) { "Expected #{mu_pp(obj)} to not be empty" }
-      assert_respond_to obj, :empty?
-      refute obj.empty?, msg
-    end
-
-    ##
-    # Fails if <tt>exp == act</tt>.
-    #
-    # For floats use refute_in_delta.
-
-    def refute_equal exp, act, msg = nil
-      msg = message(msg) {
-        "Expected #{mu_pp(act)} to not be equal to #{mu_pp(exp)}"
-      }
-      refute exp == act, msg
-    end
-
-    ##
-    # For comparing Floats.  Fails if +exp+ is within +delta+ of +act+
-    #
-    #   refute_in_delta Math::PI, (22.0 / 7.0)
-
-    def refute_in_delta exp, act, delta = 0.001, msg = nil
-      n = (exp - act).abs
-      msg = message(msg) {
-        "Expected #{exp} - #{act} (#{n}) to not be < #{delta}"
-      }
-      refute delta > n, msg
-    end
-
-    ##
-    # For comparing Floats.  Fails if +exp+ and +act+ have a relative error
-    # less than +epsilon+.
-
-    def refute_in_epsilon a, b, epsilon = 0.001, msg = nil
-      refute_in_delta a, b, a * epsilon, msg
-    end
-
-    ##
-    # Fails if +collection+ includes +obj+
-
-    def refute_includes collection, obj, msg = nil
-      msg = message(msg) {
-        "Expected #{mu_pp(collection)} to not include #{mu_pp(obj)}"
-      }
-      assert_respond_to collection, :include?
-      refute collection.include?(obj), msg
-    end
-
-    ##
-    # Fails if +obj+ is an instance of +cls+
-
-    def refute_instance_of cls, obj, msg = nil
-      msg = message(msg) {
-        "Expected #{mu_pp(obj)} to not be an instance of #{cls}"
-      }
-      refute obj.instance_of?(cls), msg
-    end
-
-    ##
-    # Fails if +obj+ is a kind of +cls+
-
-    def refute_kind_of cls, obj, msg = nil # TODO: merge with instance_of
-      msg = message(msg) { "Expected #{mu_pp(obj)} to not be a kind of #{cls}" }
-      refute obj.kind_of?(cls), msg
-    end
-
-    ##
-    # Fails if +exp+ <tt>=~</tt> +act+
-
-    def refute_match exp, act, msg = nil
-      msg = message(msg) { "Expected #{mu_pp(exp)} to not match #{mu_pp(act)}" }
-      assert_respond_to act, :"=~"
-      exp = (/#{Regexp.escape exp}/) if String === exp and String === act
-      refute exp =~ act, msg
-    end
-
-    ##
-    # Fails if +obj+ is nil.
-
-    def refute_nil obj, msg = nil
-      msg = message(msg) { "Expected #{mu_pp(obj)} to not be nil" }
-      refute obj.nil?, msg
-    end
-
-    ##
-    # Fails if +o1+ is not +op+ +o2+. Eg:
-    #
-    #   refute_operator 1, :>, 2 #=> pass
-    #   refute_operator 1, :<, 2 #=> fail
-
-    def refute_operator o1, op, o2, msg = nil
-      msg = message(msg) {
-        "Expected #{mu_pp(o1)} to not be #{op} #{mu_pp(o2)}"
-      }
-      refute o1.__send__(op, o2), msg
-    end
-
-    ##
-    # Fails if +obj+ responds to the message +meth+.
-
-    def refute_respond_to obj, meth, msg = nil
-      msg = message(msg) { "Expected #{mu_pp(obj)} to not respond to #{meth}" }
-
-      refute obj.respond_to?(meth), msg
-    end
-
-    ##
-    # Fails if +exp+ is the same (by object identity) as +act+.
-
-    def refute_same exp, act, msg = nil
-      msg = message(msg) {
-        data = [mu_pp(act), act.object_id, mu_pp(exp), exp.object_id]
-        "Expected %s (oid=%d) to not be the same as %s (oid=%d)" % data
-      }
-      refute exp.equal?(act), msg
-    end
-
-    ##
-    # Skips the current test. Gets listed at the end of the run but
-    # doesn't cause a failure exit code.
-
-    def skip msg = nil, bt = caller
-      msg ||= "Skipped, no message given"
-      raise MiniTest::Skip, msg, bt
-    end
-  end
-
-  class Unit
-    VERSION = "2.5.1" # :nodoc:
-
-    attr_accessor :report, :failures, :errors, :skips # :nodoc:
-    attr_accessor :test_count, :assertion_count       # :nodoc:
-    attr_accessor :start_time                         # :nodoc:
-    attr_accessor :help                               # :nodoc:
-    attr_accessor :verbose                            # :nodoc:
-    attr_writer   :options                            # :nodoc:
-
-    def options
-      @options ||= {}
-    end
-
-    @@installed_at_exit ||= false
-    @@out = $stdout
-
-    ##
-    # A simple hook allowing you to run a block of code after the
-    # tests are done. Eg:
-    #
-    #   MiniTest::Unit.after_tests { p $debugging_info }
-
-    def self.after_tests
-      at_exit { at_exit { yield } }
-    end
-
-    ##
-    # Registers MiniTest::Unit to run tests at process exit
-
-    def self.autorun
-      at_exit {
-        next if $! # don't run if there was an exception
-
-        # the order here is important. The at_exit handler must be
-        # installed before anyone else gets a chance to install their
-        # own, that way we can be assured that our exit will be last
-        # to run (at_exit stacks).
-        exit_code = nil
-
-        at_exit { exit false if exit_code && exit_code != 0 }
-
-        exit_code = MiniTest::Unit.new.run ARGV
-      } unless @@installed_at_exit
-      @@installed_at_exit = true
-    end
-
-    ##
-    # Returns the stream to use for output.
-
-    def self.output
-      @@out
-    end
-
-    ##
-    # Returns the stream to use for output.
-    #
-    # DEPRECATED: use ::output instead.
-
-    def self.out
-      warn "::out deprecated, use ::output instead." if $VERBOSE
-      output
-    end
-
-    ##
-    # Sets MiniTest::Unit to write output to +stream+.  $stdout is the default
-    # output
-
-    def self.output= stream
-      @@out = stream
-    end
-
-    ##
-    # Tells MiniTest::Unit to delegate to +runner+, an instance of a
-    # MiniTest::Unit subclass, when MiniTest::Unit#run is called.
-
-    def self.runner= runner
-      @@runner = runner
-    end
-
-    ##
-    # Returns the MiniTest::Unit subclass instance that will be used
-    # to run the tests. A MiniTest::Unit instance is the default
-    # runner.
-
-    def self.runner
-      @@runner ||= self.new
-    end
-
-    ##
-    # Return all plugins' run methods (methods that start with "run_").
-
-    def self.plugins
-      @@plugins ||= (["run_tests"] +
-                     public_instance_methods(false).
-                     grep(/^run_/).map { |s| s.to_s }).uniq
-    end
-
-    def output
-      self.class.output
-    end
-
-    def puts *a  # :nodoc:
-      output.puts(*a)
-    end
-
-    def print *a # :nodoc:
-      output.print(*a)
-    end
-
-    def _run_anything type
-      suites = TestCase.send "#{type}_suites"
-      return if suites.empty?
-
-      start = Time.now
-
-      puts
-      puts "# Running #{type}s:"
-      puts
-
-      @test_count, @assertion_count = 0, 0
-      sync = output.respond_to? :"sync=" # stupid emacs
-      old_sync, output.sync = output.sync, true if sync
-
-      results = _run_suites suites, type
-
-      @test_count      = results.inject(0) { |sum, (tc, _)| sum + tc }
-      @assertion_count = results.inject(0) { |sum, (_, ac)| sum + ac }
-
-      output.sync = old_sync if sync
-
-      t = Time.now - start
-
-      puts
-      puts
-      puts "Finished #{type}s in %.6fs, %.4f tests/s, %.4f assertions/s." %
-        [t, test_count / t, assertion_count / t]
-
-      report.each_with_index do |msg, i|
-        puts "\n%3d) %s" % [i + 1, msg]
-      end
-
-      puts
-
-      status
-    end
-
-    def _run_suites suites, type
-      suites.map { |suite| _run_suite suite, type }
-    end
-
-    def _run_suite suite, type
-      header = "#{type}_suite_header"
-      puts send(header, suite) if respond_to? header
-
-      filter = options[:filter] || '/./'
-      filter = Regexp.new $1 if filter =~ /\/(.*)\//
-
-      assertions = suite.send("#{type}_methods").grep(filter).map { |method|
-        inst = suite.new method
-        inst._assertions = 0
-
-        print "#{suite}##{method} = " if @verbose
-
-        @start_time = Time.now
-        result = inst.run self
-        time = Time.now - @start_time
-
-        print "%.2f s = " % time if @verbose
-        print result
-        puts if @verbose
-
-        inst._assertions
-      }
-
-      return assertions.size, assertions.inject(0) { |sum, n| sum + n }
-    end
-
-    def location e # :nodoc:
-      last_before_assertion = ""
-      e.backtrace.reverse_each do |s|
-        break if s =~ /in .(assert|refute|flunk|pass|fail|raise|must|wont)/
-        last_before_assertion = s
-      end
-      last_before_assertion.sub(/:in .*$/, '')
-    end
-
-    ##
-    # Writes status for failed test +meth+ in +klass+ which finished with
-    # exception +e+
-
-    def puke klass, meth, e
-      e = case e
-          when MiniTest::Skip then
-            @skips += 1
-            return "S" unless @verbose
-            "Skipped:\n#{meth}(#{klass}) [#{location e}]:\n#{e.message}\n"
-          when MiniTest::Assertion then
-            @failures += 1
-            "Failure:\n#{meth}(#{klass}) [#{location e}]:\n#{e.message}\n"
-          else
-            @errors += 1
-            bt = MiniTest::filter_backtrace(e.backtrace).join "\n    "
-            "Error:\n#{meth}(#{klass}):\n#{e.class}: #{e.message}\n    #{bt}\n"
-          end
-      @report << e
-      e[0, 1]
-    end
-
-    def initialize # :nodoc:
-      @report = []
-      @errors = @failures = @skips = 0
-      @verbose = false
-    end
-
-    def process_args args = []
-      options = {}
-      orig_args = args.dup
-
-      OptionParser.new do |opts|
-        opts.banner  = 'minitest options:'
-        opts.version = MiniTest::Unit::VERSION
-
-        opts.on '-h', '--help', 'Display this help.' do
-          puts opts
-          exit
-        end
-
-        opts.on '-s', '--seed SEED', Integer, "Sets random seed" do |m|
-          options[:seed] = m.to_i
-        end
-
-        opts.on '-v', '--verbose', "Verbose. Show progress processing files." do
-          options[:verbose] = true
-        end
-
-        opts.on '-n', '--name PATTERN', "Filter test names on pattern." do |a|
-          options[:filter] = a
-        end
-
-        opts.parse! args
-        orig_args -= args
-      end
-
-      unless options[:seed] then
-        srand
-        options[:seed] = srand % 0xFFFF
-        orig_args << "--seed" << options[:seed].to_s
-      end
-
-      srand options[:seed]
-
-      self.verbose = options[:verbose]
-      @help = orig_args.map { |s| s =~ /[\s|&<>$()]/ ? s.inspect : s }.join " "
-
-      options
-    end
-
-    ##
-    # Begins the full test run. Delegates to +runner+'s #_run method.
-
-    def run args = []
-      self.class.runner._run(args)
-    end
-
-    ##
-    # Top level driver, controls all output and filtering.
-
-    def _run args = []
-      self.options = process_args args
-
-      puts "Run options: #{help}"
-
-      self.class.plugins.each do |plugin|
-        send plugin
-        break unless report.empty?
-      end
-
-      return failures + errors if @test_count > 0 # or return nil...
-    rescue Interrupt
-      abort 'Interrupted'
-    end
-
-    ##
-    # Runs test suites matching +filter+.
-
-    def run_tests
-      _run_anything :test
-    end
-
-    ##
-    # Writes status to +io+
-
-    def status io = self.output
-      format = "%d tests, %d assertions, %d failures, %d errors, %d skips"
-      io.puts format % [test_count, assertion_count, failures, errors, skips]
-    end
-
-    ##
-    # Subclass TestCase to create your own tests. Typically you'll want a
-    # TestCase subclass per implementation class.
-    #
-    # See MiniTest::Assertions
-
-    class TestCase
-      attr_reader :__name__ # :nodoc:
-
-      PASSTHROUGH_EXCEPTIONS = [NoMemoryError, SignalException,
-                                Interrupt, SystemExit] # :nodoc:
-
-      SUPPORTS_INFO_SIGNAL = Signal.list['INFO'] # :nodoc:
-
-      ##
-      # Runs the tests reporting the status to +runner+
-
-      def run runner
-        trap "INFO" do
-          time = runner.start_time ? Time.now - runner.start_time : 0
-          warn "%s#%s %.2fs" % [self.class, self.__name__, time]
-          runner.status $stderr
-        end if SUPPORTS_INFO_SIGNAL
-
-        result = ""
-        begin
-          @passed = nil
-          self.setup
-          self.run_setup_hooks
-          self.__send__ self.__name__
-          result = "." unless io?
-          @passed = true
-        rescue *PASSTHROUGH_EXCEPTIONS
-          raise
-        rescue Exception => e
-          @passed = false
-          result = runner.puke self.class, self.__name__, e
-        ensure
-          begin
-            self.run_teardown_hooks
-            self.teardown
-          rescue *PASSTHROUGH_EXCEPTIONS
-            raise
-          rescue Exception => e
-            result = runner.puke self.class, self.__name__, e
-          end
-          trap 'INFO', 'DEFAULT' if SUPPORTS_INFO_SIGNAL
-        end
-        result
-      end
-
-      def initialize name # :nodoc:
-        @__name__ = name
-        @__io__ = nil
-        @passed = nil
-      end
-
-      def io
-        @__io__ = true
-        MiniTest::Unit.output
-      end
-
-      def io?
-        @__io__
-      end
-
-      def self.reset # :nodoc:
-        @@test_suites = {}
-      end
-
-      reset
-
-      ##
-      # Call this at the top of your tests when you absolutely
-      # positively need to have ordered tests. In doing so, you're
-      # admitting that you suck and your tests are weak.
-
-      def self.i_suck_and_my_tests_are_order_dependent!
-        class << self
-          define_method :test_order do :alpha end
-        end
-      end
-
-      def self.inherited klass # :nodoc:
-        @@test_suites[klass] = true
-        klass.reset_setup_teardown_hooks
-        super
-      end
-
-      def self.test_order # :nodoc:
-        :random
-      end
-
-      def self.test_suites # :nodoc:
-        @@test_suites.keys.sort_by { |ts| ts.name.to_s }
-      end
-
-      def self.test_methods # :nodoc:
-        methods = public_instance_methods(true).grep(/^test/).map { |m| m.to_s }
-
-        case self.test_order
-        when :random then
-          max = methods.size
-          methods.sort.sort_by { rand max }
-        when :alpha, :sorted then
-          methods.sort
-        else
-          raise "Unknown test_order: #{self.test_order.inspect}"
-        end
-      end
-
-      ##
-      # Returns true if the test passed.
-
-      def passed?
-        @passed
-      end
-
-      ##
-      # Runs before every test. Use this to refactor test initialization.
-
-      def setup; end
-
-      ##
-      # Runs after every test. Use this to refactor test cleanup.
-
-      def teardown; end
-
-      def self.reset_setup_teardown_hooks # :nodoc:
-        @setup_hooks = []
-        @teardown_hooks = []
-      end
-
-      reset_setup_teardown_hooks
-
-      ##
-      # Adds a block of code that will be executed before every TestCase is
-      # run. Equivalent to +setup+, but usable multiple times and without
-      # re-opening any classes.
-      #
-      # All of the setup hooks will run in order after the +setup+ method, if
-      # one is defined.
-      #
-      # The argument can be any object that responds to #call or a block.
-      # That means that this call,
-      #
-      #     MiniTest::TestCase.add_setup_hook { puts "foo" }
-      #
-      # ... is equivalent to:
-      #
-      #     module MyTestSetup
-      #       def call
-      #         puts "foo"
-      #       end
-      #     end
-      #
-      #     MiniTest::TestCase.add_setup_hook MyTestSetup
-      #
-      # The blocks passed to +add_setup_hook+ take an optional parameter that
-      # will be the TestCase instance that is executing the block.
-
-      def self.add_setup_hook arg=nil, &block
-        hook = arg || block
-        @setup_hooks << hook
-      end
-
-      def self.setup_hooks # :nodoc:
-        if superclass.respond_to? :setup_hooks then
-          superclass.setup_hooks
-        else
-          []
-        end + @setup_hooks
-      end
-
-      def run_setup_hooks # :nodoc:
-        self.class.setup_hooks.each do |hook|
-          if hook.respond_to?(:arity) && hook.arity == 1
-            hook.call(self)
-          else
-            hook.call
-          end
-        end
-      end
-
-      ##
-      # Adds a block of code that will be executed after every TestCase is
-      # run. Equivalent to +teardown+, but usable multiple times and without
-      # re-opening any classes.
-      #
-      # All of the teardown hooks will run in reverse order after the
-      # +teardown+ method, if one is defined.
-      #
-      # The argument can be any object that responds to #call or a block.
-      # That means that this call,
-      #
-      #     MiniTest::TestCase.add_teardown_hook { puts "foo" }
-      #
-      # ... is equivalent to:
-      #
-      #     module MyTestTeardown
-      #       def call
-      #         puts "foo"
-      #       end
-      #     end
-      #
-      #     MiniTest::TestCase.add_teardown_hook MyTestTeardown
-      #
-      # The blocks passed to +add_teardown_hook+ take an optional parameter
-      # that will be the TestCase instance that is executing the block.
-
-      def self.add_teardown_hook arg=nil, &block
-        hook = arg || block
-        @teardown_hooks << hook
-      end
-
-      def self.teardown_hooks # :nodoc:
-        if superclass.respond_to? :teardown_hooks then
-          superclass.teardown_hooks
-        else
-          []
-        end + @teardown_hooks
-      end
-
-      def run_teardown_hooks # :nodoc:
-        self.class.teardown_hooks.reverse.each do |hook|
-          if hook.respond_to?(:arity) && hook.arity == 1
-            hook.call(self)
-          else
-            hook.call
-          end
-        end
-      end
-
-      include MiniTest::Assertions
-    end # class TestCase
-  end # class Unit
-end # module MiniTest
-
-if $DEBUG then
-  module Test                # :nodoc:
-    module Unit              # :nodoc:
-      class TestCase         # :nodoc:
-        def self.inherited x # :nodoc:
-          # this helps me ferret out porting issues
-          raise "Using minitest and test/unit in the same process: #{x}"
-        end
-      end
-    end
-  end
-end
diff --git a/lib/mkmf.rb b/lib/mkmf.rb
index 898e4a78c9..37ee4a70d9 100644
--- a/lib/mkmf.rb
+++ b/lib/mkmf.rb
@@ -1,4 +1,5 @@
-# -*- indent-tabs-mode: t -*-
+# -*- coding: us-ascii -*-
+# frozen-string-literal: false
 # module to create Makefile for extension modules
 # invoke like: ruby -r mkmf extconf.rb
 
@@ -6,1694 +7,2145 @@ require 'rbconfig'
 require 'fileutils'
 require 'shellwords'
 
-CONFIG = RbConfig::MAKEFILE_CONFIG
-ORIG_LIBPATH = ENV['LIB']
+class String # :nodoc:
+  # Wraps a string in escaped quotes if it contains whitespace.
+  def quote
+    /\s/ =~ self ? "\"#{self}\"" : "#{self}"
+  end
 
-C_EXT = %w[c m]
-CXX_EXT = %w[cc mm cxx cpp]
-if File::FNM_SYSCASE.zero?
-  CXX_EXT.concat(%w[C])
-end
-SRC_EXT = C_EXT + CXX_EXT
-$static = nil
-$config_h = '$(arch_hdrdir)/ruby/config.h'
-$default_static = $static
-
-unless defined? $configure_args
-  $configure_args = {}
-  args = CONFIG["configure_args"]
-  if ENV["CONFIGURE_ARGS"]
-    args << " " << ENV["CONFIGURE_ARGS"]
-  end
-  for arg in Shellwords::shellwords(args)
-    arg, val = arg.split('=', 2)
-    next unless arg
-    arg.tr!('_', '-')
-    if arg.sub!(/^(?!--)/, '--')
-      val or next
-      arg.downcase!
-    end
-    next if /^--(?:top|topsrc|src|cur)dir$/ =~ arg
-    $configure_args[arg] = val || true
-  end
-  for arg in ARGV
-    arg, val = arg.split('=', 2)
-    next unless arg
-    arg.tr!('_', '-')
-    if arg.sub!(/^(?!--)/, '--')
-      val or next
-      arg.downcase!
-    end
-    $configure_args[arg] = val || true
+  # Escape whitespaces for Makefile.
+  def unspace
+    gsub(/\s/, '\\\\\\&')
   end
-end
 
-$libdir = CONFIG["libdir"]
-$rubylibdir = CONFIG["rubylibdir"]
-$archdir = CONFIG["archdir"]
-$sitedir = CONFIG["sitedir"]
-$sitelibdir = CONFIG["sitelibdir"]
-$sitearchdir = CONFIG["sitearchdir"]
-$vendordir = CONFIG["vendordir"]
-$vendorlibdir = CONFIG["vendorlibdir"]
-$vendorarchdir = CONFIG["vendorarchdir"]
-
-$mswin = /mswin/ =~ RUBY_PLATFORM
-$bccwin = /bccwin/ =~ RUBY_PLATFORM
-$mingw = /mingw/ =~ RUBY_PLATFORM
-$cygwin = /cygwin/ =~ RUBY_PLATFORM
-$netbsd = /netbsd/ =~ RUBY_PLATFORM
-$os2 = /os2/ =~ RUBY_PLATFORM
-$beos = /beos/ =~ RUBY_PLATFORM
-$haiku = /haiku/ =~ RUBY_PLATFORM
-$solaris = /solaris/ =~ RUBY_PLATFORM
-$universal = /universal/ =~ RUBY_PLATFORM
-$dest_prefix_pattern = (File::PATH_SEPARATOR == ';' ? /\A([[:alpha:]]:)?/ : /\A/)
-
-# :stopdoc:
-
-def config_string(key, config = CONFIG)
-  s = config[key] and !s.empty? and block_given? ? yield(s) : s
-end
+  # Generates a string used as cpp macro name.
+  def tr_cpp
+    strip.upcase.tr_s("^A-Z0-9_*", "_").tr_s("*", "P")
+  end
 
-def dir_re(dir)
-  Regexp.new('\$(?:\('+dir+'\)|\{'+dir+'\})(?:\$(?:\(target_prefix\)|\{target_prefix\}))?')
+  def funcall_style
+    /\)\z/ =~ self ? dup : "#{self}()"
+  end
+
+  def sans_arguments
+    self[/\A[^()]+/]
+  end
 end
 
-def relative_from(path, base)
-  dir = File.join(path, "")
-  if File.expand_path(dir) == File.expand_path(dir, base)
-    path
-  else
-    File.join(base, path)
+class Array # :nodoc:
+  # Wraps all strings in escaped quotes if they contain whitespace.
+  def quote
+    map {|s| s.quote}
   end
 end
 
-INSTALL_DIRS = [
-  [dir_re('commondir'), "$(RUBYCOMMONDIR)"],
-  [dir_re('sitedir'), "$(RUBYCOMMONDIR)"],
-  [dir_re('vendordir'), "$(RUBYCOMMONDIR)"],
-  [dir_re('rubylibdir'), "$(RUBYLIBDIR)"],
-  [dir_re('archdir'), "$(RUBYARCHDIR)"],
-  [dir_re('sitelibdir'), "$(RUBYLIBDIR)"],
-  [dir_re('vendorlibdir'), "$(RUBYLIBDIR)"],
-  [dir_re('sitearchdir'), "$(RUBYARCHDIR)"],
-  [dir_re('vendorarchdir'), "$(RUBYARCHDIR)"],
-  [dir_re('rubyhdrdir'), "$(RUBYHDRDIR)"],
-  [dir_re('sitehdrdir'), "$(SITEHDRDIR)"],
-  [dir_re('vendorhdrdir'), "$(VENDORHDRDIR)"],
-  [dir_re('bindir'), "$(BINDIR)"],
-]
-
-def install_dirs(target_prefix = nil)
-  if $extout
-    dirs = [
-      ['BINDIR',        '$(extout)/bin'],
-      ['RUBYCOMMONDIR', '$(extout)/common'],
-      ['RUBYLIBDIR',    '$(RUBYCOMMONDIR)$(target_prefix)'],
-      ['RUBYARCHDIR',   '$(extout)/$(arch)$(target_prefix)'],
-      ['HDRDIR',        '$(extout)/include/ruby$(target_prefix)'],
-      ['ARCHHDRDIR',    '$(extout)/include/$(arch)/ruby$(target_prefix)'],
-      ['extout',        "#$extout"],
-      ['extout_prefix', "#$extout_prefix"],
-    ]
-  elsif $extmk
-    dirs = [
-      ['BINDIR',        '$(bindir)'],
-      ['RUBYCOMMONDIR', '$(rubylibdir)'],
-      ['RUBYLIBDIR',    '$(rubylibdir)$(target_prefix)'],
-      ['RUBYARCHDIR',   '$(archdir)$(target_prefix)'],
-      ['HDRDIR',        '$(rubyhdrdir)/ruby$(target_prefix)'],
-      ['ARCHHDRDIR',    '$(rubyhdrdir)/$(arch)/ruby$(target_prefix)'],
-    ]
-  elsif $configure_args.has_key?('--vendor')
-    dirs = [
-      ['BINDIR',        '$(bindir)'],
-      ['RUBYCOMMONDIR', '$(vendordir)$(target_prefix)'],
-      ['RUBYLIBDIR',    '$(vendorlibdir)$(target_prefix)'],
-      ['RUBYARCHDIR',   '$(vendorarchdir)$(target_prefix)'],
-      ['HDRDIR',        '$(rubyhdrdir)/ruby$(target_prefix)'],
-      ['ARCHHDRDIR',    '$(rubyhdrdir)/$(arch)/ruby$(target_prefix)'],
-    ]
+##
+# \Module \MakeMakefile is used by Ruby C extensions to generate a Makefile which will
+# correctly compile and link the C extension to Ruby and a third-party
+# library.
+module MakeMakefile
+
+  target_rbconfig = nil
+  ARGV.delete_if do |arg|
+    opt = arg.delete_prefix("--target-rbconfig=")
+    unless opt == arg
+      target_rbconfig = opt
+    end
+  end
+  if target_rbconfig
+    # Load the RbConfig for the target platform into this module.
+    # Cross-compiling needs the same version of Ruby.
+    Kernel.load target_rbconfig, self
   else
-    dirs = [
-      ['BINDIR',        '$(bindir)'],
-      ['RUBYCOMMONDIR', '$(sitedir)$(target_prefix)'],
-      ['RUBYLIBDIR',    '$(sitelibdir)$(target_prefix)'],
-      ['RUBYARCHDIR',   '$(sitearchdir)$(target_prefix)'],
-      ['HDRDIR',        '$(rubyhdrdir)/ruby$(target_prefix)'],
-      ['ARCHHDRDIR',    '$(rubyhdrdir)/$(arch)/ruby$(target_prefix)'],
-    ]
+    # The RbConfig for the target platform where the built extension runs.
+    RbConfig = ::RbConfig
   end
-  dirs << ['target_prefix', (target_prefix ? "/#{target_prefix}" : "")]
-  dirs
-end
 
-def map_dir(dir, map = nil)
-  map ||= INSTALL_DIRS
-  map.inject(dir) {|d, (orig, new)| d.gsub(orig, new)}
-end
+  #### defer until this module become global-state free.
+  # def self.extended(obj)
+  #   obj.init_mkmf
+  #   super
+  # end
+  #
+  # def initialize(*args, rbconfig: RbConfig, **rest)
+  #   init_mkmf(rbconfig::MAKEFILE_CONFIG, rbconfig::CONFIG)
+  #   super(*args, **rest)
+  # end
 
-topdir = File.dirname(File.dirname(__FILE__))
-path = File.expand_path($0)
-$extmk = path[0, topdir.size+1] == topdir+"/"
-$extmk &&= %r"\A(?:ext|enc|tool|test(?:/.+)?)\z" =~ File.dirname(path[topdir.size+1..-1])
-$extmk &&= true
-if not $extmk and File.exist?(($hdrdir = RbConfig::CONFIG["rubyhdrdir"]) + "/ruby/ruby.h")
-  $topdir = $hdrdir
-  $top_srcdir = $hdrdir
-  $arch_hdrdir = $hdrdir + "/$(arch)"
-elsif File.exist?(($hdrdir = ($top_srcdir ||= topdir) + "/include")  + "/ruby.h")
-  $topdir ||= RbConfig::CONFIG["topdir"]
-  $arch_hdrdir = "$(extout)/include/$(arch)"
-else
-  abort "mkmf.rb can't find header files for ruby at #{$hdrdir}/ruby.h"
-end
+  ##
+  # The makefile configuration using the defaults from when Ruby was built.
 
-OUTFLAG = CONFIG['OUTFLAG']
-COUTFLAG = CONFIG['COUTFLAG']
-CPPOUTFILE = CONFIG['CPPOUTFILE']
+  CONFIG = RbConfig::MAKEFILE_CONFIG
 
-CONFTEST_C = "conftest.c".freeze
+  ##
+  # The saved original value of +LIB+ environment variable
+  ORIG_LIBPATH = ENV['LIB']
 
-class String
-  # Wraps a string in escaped quotes if it contains whitespace.
-  def quote
-    /\s/ =~ self ? "\"#{self}\"" : "#{self}"
+  ##
+  # Extensions for files compiled with a C compiler
+
+  C_EXT = %w[c m]
+
+  ##
+  # Extensions for files compiled with a C++ compiler
+
+  CXX_EXT = %w[cc mm cxx cpp]
+  unless File.exist?(File.join(*File.split(__FILE__).tap {|d, b| b.swapcase}))
+    CXX_EXT.concat(%w[C])
   end
 
-  # Generates a string used as cpp macro name.
-  def tr_cpp
-    strip.upcase.tr_s("^A-Z0-9_*", "_").tr_s("*", "P")
+  ##
+  # Extensions for source files
+
+  SRC_EXT = C_EXT + CXX_EXT
+
+  ##
+  # Extensions for header files
+
+  HDR_EXT = %w[h hpp]
+  $static = nil
+  $config_h = '$(arch_hdrdir)/ruby/config.h'
+  $default_static = $static
+
+  unless defined? $configure_args
+    $configure_args = {}
+    args = CONFIG["configure_args"].shellsplit
+    if arg = ENV["CONFIGURE_ARGS"]
+      args.push(*arg.shellsplit)
+    end
+    args.delete_if {|a| /\A--(?:top(?:src)?|src|cur)dir(?=\z|=)/ =~ a}
+    for arg in args.concat(ARGV)
+      arg, val = arg.split('=', 2)
+      next unless arg
+      arg.tr!('_', '-')
+      if arg.sub!(/\A(?!--)/, '--')
+        val or next
+        arg.downcase!
+      end
+      $configure_args[arg] = val || true
+    end
   end
-end
-class Array
-  # Wraps all strings in escaped quotes if they contain whitespace.
-  def quote
-    map {|s| s.quote}
+
+  $libdir = CONFIG["libdir"]
+  $rubylibdir = CONFIG["rubylibdir"]
+  $archdir = CONFIG["archdir"]
+  $sitedir = CONFIG["sitedir"]
+  $sitelibdir = CONFIG["sitelibdir"]
+  $sitearchdir = CONFIG["sitearchdir"]
+  $vendordir = CONFIG["vendordir"]
+  $vendorlibdir = CONFIG["vendorlibdir"]
+  $vendorarchdir = CONFIG["vendorarchdir"]
+
+  $mswin = /mswin/ =~ RUBY_PLATFORM
+  $mingw = /mingw/ =~ RUBY_PLATFORM
+  $cygwin = /cygwin/ =~ RUBY_PLATFORM
+  $netbsd = /netbsd/ =~ RUBY_PLATFORM
+  $haiku = /haiku/ =~ RUBY_PLATFORM
+  $solaris = /solaris/ =~ RUBY_PLATFORM
+  $universal = /universal/ =~ RUBY_PLATFORM
+  $dest_prefix_pattern = (File::PATH_SEPARATOR == ';' ? /\A([[:alpha:]]:)?/ : /\A/)
+
+  # :stopdoc:
+
+  def config_string(key, config = CONFIG)
+    s = config[key] and !s.empty? and block_given? ? yield(s) : s
   end
-end
+  module_function :config_string
 
-def rm_f(*files)
-  opt = (Hash === files.last ? [files.pop] : [])
-  FileUtils.rm_f(Dir[*files.flatten], *opt)
-end
+  def dir_re(dir)
+    Regexp.new('\$(?:\('+dir+'\)|\{'+dir+'\})(?:\$(?:\(target_prefix\)|\{target_prefix\}))?')
+  end
+  module_function :dir_re
 
-def rm_rf(*files)
-  opt = (Hash === files.last ? [files.pop] : [])
-  FileUtils.rm_rf(Dir[*files.flatten], *opt)
-end
+  def relative_from(path, base)
+    dir = File.join(path, "")
+    if File.expand_path(dir) == File.expand_path(dir, base)
+      path
+    else
+      File.join(base, path)
+    end
+  end
 
-# Returns time stamp of the +target+ file if it exists and is newer
-# than or equal to all of +times+.
-def modified?(target, times)
-  (t = File.mtime(target)) rescue return nil
-  Array === times or times = [times]
-  t if times.all? {|n| n <= t}
-end
+  INSTALL_DIRS = [
+    [dir_re('commondir'), "$(RUBYCOMMONDIR)"],
+    [dir_re('sitedir'), "$(RUBYCOMMONDIR)"],
+    [dir_re('vendordir'), "$(RUBYCOMMONDIR)"],
+    [dir_re('rubylibdir'), "$(RUBYLIBDIR)"],
+    [dir_re('archdir'), "$(RUBYARCHDIR)"],
+    [dir_re('sitelibdir'), "$(RUBYLIBDIR)"],
+    [dir_re('vendorlibdir'), "$(RUBYLIBDIR)"],
+    [dir_re('sitearchdir'), "$(RUBYARCHDIR)"],
+    [dir_re('vendorarchdir'), "$(RUBYARCHDIR)"],
+    [dir_re('rubyhdrdir'), "$(RUBYHDRDIR)"],
+    [dir_re('sitehdrdir'), "$(SITEHDRDIR)"],
+    [dir_re('vendorhdrdir'), "$(VENDORHDRDIR)"],
+    [dir_re('bindir'), "$(BINDIR)"],
+  ]
+
+  def install_dirs(target_prefix = nil)
+    if $extout and $extmk
+      dirs = [
+        ['BINDIR',        '$(extout)/bin'],
+        ['RUBYCOMMONDIR', '$(extout)/common'],
+        ['RUBYLIBDIR',    '$(RUBYCOMMONDIR)$(target_prefix)'],
+        ['RUBYARCHDIR',   '$(extout)/$(arch)$(target_prefix)'],
+        ['HDRDIR',        '$(extout)/include/ruby$(target_prefix)'],
+        ['ARCHHDRDIR',    '$(extout)/include/$(arch)/ruby$(target_prefix)'],
+        ['extout',        "#$extout"],
+        ['extout_prefix', "#$extout_prefix"],
+      ]
+    elsif $extmk
+      dirs = [
+        ['BINDIR',        '$(bindir)'],
+        ['RUBYCOMMONDIR', '$(rubylibdir)'],
+        ['RUBYLIBDIR',    '$(rubylibdir)$(target_prefix)'],
+        ['RUBYARCHDIR',   '$(archdir)$(target_prefix)'],
+        ['HDRDIR',        '$(rubyhdrdir)/ruby$(target_prefix)'],
+        ['ARCHHDRDIR',    '$(rubyhdrdir)/$(arch)/ruby$(target_prefix)'],
+      ]
+    elsif $configure_args.has_key?('--vendor')
+      dirs = [
+        ['BINDIR',        '$(bindir)'],
+        ['RUBYCOMMONDIR', '$(vendordir)$(target_prefix)'],
+        ['RUBYLIBDIR',    '$(vendorlibdir)$(target_prefix)'],
+        ['RUBYARCHDIR',   '$(vendorarchdir)$(target_prefix)'],
+        ['HDRDIR',        '$(vendorhdrdir)$(target_prefix)'],
+        ['ARCHHDRDIR',    '$(vendorarchhdrdir)$(target_prefix)'],
+      ]
+    else
+      dirs = [
+        ['BINDIR',        '$(bindir)'],
+        ['RUBYCOMMONDIR', '$(sitedir)$(target_prefix)'],
+        ['RUBYLIBDIR',    '$(sitelibdir)$(target_prefix)'],
+        ['RUBYARCHDIR',   '$(sitearchdir)$(target_prefix)'],
+        ['HDRDIR',        '$(sitehdrdir)$(target_prefix)'],
+        ['ARCHHDRDIR',    '$(sitearchhdrdir)$(target_prefix)'],
+      ]
+    end
+    dirs << ['target_prefix', (target_prefix ? "/#{target_prefix}" : "")]
+    dirs
+  end
 
-def merge_libs(*libs)
-  libs.inject([]) do |x, y|
-    xy = x & y
-    xn = yn = 0
-    y = y.inject([]) {|ary, e| ary.last == e ? ary : ary << e}
-    y.each_with_index do |v, yi|
-      if xy.include?(v)
-        xi = [x.index(v), xn].max()
-        x[xi, 1] = y[yn..yi]
-        xn, yn = xi + (yi - yn + 1), yi + 1
-      end
+  def map_dir(dir, map = nil)
+    map ||= INSTALL_DIRS
+    map.inject(dir) {|d, (orig, new)| d.gsub(orig, new)}
+  end
+
+  topdir = File.dirname(File.dirname(__FILE__))
+  path = File.expand_path($0)
+  until (dir = File.dirname(path)) == path
+    if File.identical?(dir, topdir)
+      $extmk = true if %r"\A(?:ext|enc|tool|test)\z" =~ File.basename(path)
+      break
     end
-    x.concat(y[yn..-1] || [])
+    path = dir
+  end
+  $extmk ||= false
+  if not $extmk and File.exist?(($hdrdir = RbConfig::CONFIG["rubyhdrdir"]) + "/ruby/ruby.h")
+    $topdir = $hdrdir
+    $top_srcdir = $hdrdir
+    $arch_hdrdir = RbConfig::CONFIG["rubyarchhdrdir"]
+  elsif File.exist?(($hdrdir = ($top_srcdir ||= topdir) + "/include")  + "/ruby.h")
+    $topdir ||= RbConfig::CONFIG["topdir"]
+    $arch_hdrdir = "$(extout)/include/$(arch)"
+  else
+    abort <<MESSAGE
+mkmf.rb can't find header files for ruby at #{$hdrdir}/ruby.h
+
+You might have to install separate package for the ruby development
+environment, ruby-dev or ruby-devel for example.
+MESSAGE
   end
-end
 
-# This is a custom logging module. It generates an mkmf.log file when you
-# run your extconf.rb script. This can be useful for debugging unexpected
-# failures.
-#
-# This module and its associated methods are meant for internal use only.
-#
-module Logging
-  @log = nil
-  @logfile = 'mkmf.log'
-  @orgerr = $stderr.dup
-  @orgout = $stdout.dup
-  @postpone = 0
-  @quiet = $extmk
-
-  def self::log_open
-    @log ||= File::open(@logfile, 'wb')
-    @log.sync = true
-  end
-
-  def self::open
-    log_open
-    $stderr.reopen(@log)
-    $stdout.reopen(@log)
-    yield
-  ensure
-    $stderr.reopen(@orgerr)
-    $stdout.reopen(@orgout)
+  CONFTEST = "conftest".freeze
+  CONFTEST_C = "#{CONFTEST}.c"
+
+  OUTFLAG = CONFIG['OUTFLAG']
+  COUTFLAG = CONFIG['COUTFLAG']
+  CSRCFLAG = CONFIG['CSRCFLAG']
+  CPPOUTFILE = config_string('CPPOUTFILE') {|str| str.sub(/\bconftest\b/, CONFTEST)}
+
+  # :startdoc:
+
+  # Removes _files_.
+  def rm_f(*files)
+    opt = (Hash === files.last ? [files.pop] : [])
+    FileUtils.rm_f(Dir[*files.flatten], *opt)
   end
+  module_function :rm_f
 
-  def self::message(*s)
-    log_open
-    @log.printf(*s)
+  # Removes _files_ recursively.
+  def rm_rf(*files)
+    opt = (Hash === files.last ? [files.pop] : [])
+    FileUtils.rm_rf(Dir[*files.flatten], *opt)
   end
+  module_function :rm_rf
+
+  # Returns time stamp of the +target+ file if it exists and is newer than or
+  # equal to all of +times+.
+  def modified?(target, times)
+    (t = File.mtime(target)) rescue return nil
+    Array === times or times = [times]
+    t if times.all? {|n| n <= t}
+  end
+
+  # :stopdoc:
 
-  def self::logfile file
-    @logfile = file
-    log_close
+  def split_libs(*strs)
+    sep = $mswin ? /\s+/ : /\s+(?=-|\z)/
+    strs.flat_map {|s| s.lstrip.split(sep)}
   end
 
-  def self::log_close
-    if @log and not @log.closed?
-      @log.flush
-      @log.close
-      @log = nil
+  def merge_libs(*libs)
+    libs.inject([]) do |x, y|
+      y = y.inject([]) {|ary, e| ary.last == e ? ary : ary << e}
+      y.each_with_index do |v, yi|
+        if xi = x.rindex(v)
+          x[(xi+1)..-1] = merge_libs(y[(yi+1)..-1], x[(xi+1)..-1])
+          x[xi, 0] = y[0...yi]
+          break
+        end
+      end and x.concat(y)
+      x
     end
   end
 
-  def self::postpone
-    tmplog = "mkmftmp#{@postpone += 1}.log"
-    open do
-      log, *save = @log, @logfile, @orgout, @orgerr
-      @log, @logfile, @orgout, @orgerr = nil, tmplog, log, log
-      begin
-        log.print(open {yield @log})
-      ensure
-        @log.close if @log and not @log.closed?
-        File::open(tmplog) {|t| FileUtils.copy_stream(t, log)} if File.exist?(tmplog)
-        @log, @logfile, @orgout, @orgerr = log, *save
-        @postpone -= 1
-        rm_f tmplog
+  # This is a custom logging module. It generates an mkmf.log file when you
+  # run your extconf.rb script. This can be useful for debugging unexpected
+  # failures.
+  #
+  # This module and its associated methods are meant for internal use only.
+  #
+  module Logging
+    @log = nil
+    @logfile = 'mkmf.log'
+    @orgerr = $stderr.dup
+    @orgout = $stdout.dup
+    @postpone = 0
+    @quiet = $extmk
+
+    def self::log_open
+      @log ||= File::open(@logfile, 'wb')
+      @log.sync = true
+    end
+
+    def self::log_opened?
+      @log and not @log.closed?
+    end
+
+    def self::open
+      log_open
+      $stderr.reopen(@log)
+      $stdout.reopen(@log)
+      yield
+    ensure
+      $stderr.reopen(@orgerr)
+      $stdout.reopen(@orgout)
+    end
+
+    def self::message(*s)
+      log_open
+      @log.printf(*s)
+    end
+
+    def self::logfile file
+      @logfile = file
+      log_close
+    end
+
+    def self::log_close
+      if @log and not @log.closed?
+        @log.flush
+        @log.close
+        @log = nil
+      end
+    end
+
+    def self::postpone
+      tmplog = "mkmftmp#{@postpone += 1}.log"
+      open do
+        log, *save = @log, @logfile, @orgout, @orgerr
+        @log, @logfile, @orgout, @orgerr = nil, tmplog, log, log
+        begin
+          log.print(open {yield @log})
+        ensure
+          @log.close if @log and not @log.closed?
+          File::open(tmplog) {|t| FileUtils.copy_stream(t, log)} if File.exist?(tmplog)
+          @log, @logfile, @orgout, @orgerr = log, *save
+          @postpone -= 1
+          MakeMakefile.rm_f tmplog
+        end
       end
     end
-  end
 
-  class << self
-    attr_accessor :quiet
+    class << self
+      attr_accessor :quiet
+    end
   end
-end
 
-def xsystem command, opts = nil
-  varpat = /\$\((\w+)\)|\$\{(\w+)\}/
-  if varpat =~ command
-    vars = Hash.new {|h, k| h[k] = ENV[k]}
-    command = command.dup
-    nil while command.gsub!(varpat) {vars[$1||$2]}
-  end
-  Logging::open do
-    puts command.quote
-    if opts and opts[:werror]
-      result = nil
-      Logging.postpone do |log|
-        result = (system(command) and File.zero?(log.path))
-        ""
-      end
-      result
+  def libpath_env
+    # used only if native compiling
+    if libpathenv = config_string("LIBPATHENV")
+      pathenv = ENV[libpathenv]
+      libpath = RbConfig.expand($DEFLIBPATH.join(File::PATH_SEPARATOR))
+      {libpathenv => [libpath, pathenv].compact.join(File::PATH_SEPARATOR)}
     else
-      system(command)
+      {}
     end
   end
-end
 
-def xpopen command, *mode, &block
-  Logging::open do
-    case mode[0]
-    when nil, /^r/
-      puts "#{command} |"
-    else
-      puts "| #{command}"
+  def expand_command(commands, envs = libpath_env)
+    varpat = /\$\((\w+)\)|\$\{(\w+)\}/
+    vars = nil
+    expand = proc do |command|
+      case command
+      when Array
+        command.map(&expand)
+      when String
+        if varpat =~ command
+          vars ||= Hash.new {|h, k| h[k] = ENV[k]}
+          command = command.dup
+          nil while command.gsub!(varpat) {vars[$1||$2]}
+        end
+        command
+      else
+        command
+      end
+    end
+    if Array === commands
+      env, *commands = commands if Hash === commands.first
+      envs.merge!(env) if env
     end
-    IO.popen(command, *mode, &block)
+
+    # disable ASAN leak reporting - conftest programs almost always don't bother
+    # to free their memory.
+    envs['LSAN_OPTIONS'] = "detect_leaks=0" unless ENV.key?('LSAN_OPTIONS')
+
+    return envs, expand[commands]
   end
-end
 
-def log_src(src, heading="checked program was")
-  src = src.split(/^/)
-  fmt = "%#{src.size.to_s.size}d: %s"
-  Logging::message <<"EOM"
+  def env_quote(envs)
+    envs.map {|e, v| "#{e}=#{v.quote}"}
+  end
+
+  # :startdoc:
+
+  # call-seq:
+  #   xsystem(command, werror: false)   -> true or false
+  #
+  # Executes _command_ with expanding variables, and returns the exit
+  # status like as Kernel#system.  If _werror_ is true and the error
+  # output is not empty, returns +false+.  The output will logged.
+  def xsystem(command, werror: false)
+    env, command = expand_command(command)
+    Logging::open do
+      puts [env_quote(env), command.quote].join(' ')
+      if werror
+        result = nil
+        Logging.postpone do |log|
+          output = IO.popen(env, command, &:read)
+          result = ($?.success? and File.zero?(log.path))
+          output
+        end
+        result
+      else
+        system(env, *command)
+      end
+    end
+  end
+
+  # Executes _command_ similarly to xsystem, but yields opened pipe.
+  def xpopen command, *mode, &block
+    env, commands = expand_command(command)
+    command = [env_quote(env), command].join(' ')
+    Logging::open do
+      case mode[0]
+      when nil, Hash, /^r/
+        puts "#{command} |"
+      else
+        puts "| #{command}"
+      end
+      IO.popen(env, commands, *mode, &block)
+    end
+  end
+
+  # Logs _src_
+  def log_src(src, heading="checked program was")
+    src = src.split(/^/)
+    fmt = "%#{src.size.to_s.size}d: %s"
+    Logging::message <<"EOM"
 #{heading}:
 /* begin */
 EOM
-  src.each_with_index {|line, no| Logging::message fmt, no+1, line}
-  Logging::message <<"EOM"
+    src.each_with_index {|line, no| Logging::message fmt, no+1, line}
+    Logging::message <<"EOM"
 /* end */
 
 EOM
-end
+  end
 
-def create_tmpsrc(src)
-  src = "#{COMMON_HEADERS}\n#{src}"
-  src = yield(src) if block_given?
-  src.gsub!(/[ \t]+$/, '')
-  src.gsub!(/\A\n+|^\n+$/, '')
-  src.sub!(/[^\n]\z/, "\\&\n")
-  count = 0
-  begin
-    open(CONFTEST_C, "wb") do |cfile|
-      cfile.print src
-    end
-  rescue Errno::EACCES
-    if (count += 1) < 5
-      sleep 0.2
-      retry
+  # Returns the language-dependent source file name for configuration
+  # checks.
+  def conftest_source
+    CONFTEST_C
+  end
+
+  # Creats temporary source file from +COMMON_HEADERS+ and _src_.
+  # Yields the created source string and uses the returned string as
+  # the source code, if the block is given.
+  def create_tmpsrc(src)
+    src = "#{COMMON_HEADERS}\n#{src}"
+    src = yield(src) if block_given?
+    src.gsub!(/[ \t]+$/, '')
+    src.gsub!(/\A\n+|^\n+$/, '')
+    src.sub!(/[^\n]\z/, "\\&\n")
+    count = 0
+    begin
+      File.open(conftest_source, "wb") do |cfile|
+        cfile.print src
+      end
+    rescue Errno::EACCES
+      if (count += 1) < 5
+        sleep 0.2
+        retry
+      end
     end
+    src
   end
-  src
-end
 
-def have_devel?
-  unless defined? $have_devel
-    $have_devel = true
-    $have_devel = try_link(MAIN_DOES_NOTHING)
+  # :stopdoc:
+
+  def have_devel?
+    unless defined? $have_devel
+      $have_devel = true
+      $have_devel = try_link(MAIN_DOES_NOTHING)
+    end
+    $have_devel
   end
-  $have_devel
-end
 
-def try_do(src, command, *opts, &b)
-  unless have_devel?
-    raise <<MSG
+  def try_do(src, command, **opts, &b)
+    unless have_devel?
+      raise <<MSG
 The compiler failed to generate an executable file.
 You have to install development tools first.
 MSG
+    end
+    begin
+      src = create_tmpsrc(src, &b)
+      xsystem(command, **opts)
+    ensure
+      log_src(src)
+    end
   end
-  begin
-    src = create_tmpsrc(src, &b)
-    xsystem(command, *opts)
-  ensure
-    log_src(src)
-    rm_rf 'conftest.dSYM'
-  end
-end
 
-def link_command(ldflags, opt="", libpath=$DEFLIBPATH|$LIBPATH)
-  librubyarg = $extmk ? $LIBRUBYARG_STATIC : "$(LIBRUBYARG)"
-  conf = RbConfig::CONFIG.merge('hdrdir' => $hdrdir.quote,
-                                'src' => "#{CONFTEST_C}",
-                                'arch_hdrdir' => $arch_hdrdir.quote,
-                                'top_srcdir' => $top_srcdir.quote,
-                                'INCFLAGS' => "#$INCFLAGS",
-                                'CPPFLAGS' => "#$CPPFLAGS",
-                                'CFLAGS' => "#$CFLAGS",
-                                'ARCH_FLAG' => "#$ARCH_FLAG",
-                                'LDFLAGS' => "#$LDFLAGS #{ldflags}",
-                                'LOCAL_LIBS' => "#$LOCAL_LIBS #$libs",
-                                'LIBS' => "#{librubyarg} #{opt} #$LIBS")
-  conf['LIBPATH'] = libpathflag(libpath.map {|s| RbConfig::expand(s.dup, conf)})
-  RbConfig::expand(TRY_LINK.dup, conf)
-end
+  def link_config(ldflags, opt="", libpath=$DEFLIBPATH|$LIBPATH)
+    librubyarg = $extmk ? $LIBRUBYARG_STATIC : "$(LIBRUBYARG)"
+    conf = RbConfig::CONFIG.merge('hdrdir' => $hdrdir.quote,
+                                  'src' => "#{conftest_source}",
+                                  'arch_hdrdir' => $arch_hdrdir.quote,
+                                  'top_srcdir' => $top_srcdir.quote,
+                                  'INCFLAGS' => "#$INCFLAGS",
+                                  'CPPFLAGS' => "#$CPPFLAGS",
+                                  'CFLAGS' => "#$CFLAGS",
+                                  'ARCH_FLAG' => "#$ARCH_FLAG",
+                                  'LDFLAGS' => "#$LDFLAGS #{ldflags}",
+                                  'LOCAL_LIBS' => "#$LOCAL_LIBS #$libs",
+                                  'LIBS' => "#{librubyarg} #{opt} #$LIBS")
+    conf['LIBPATH'] = libpathflag(libpath.map {|s| RbConfig::expand(s.dup, conf)})
+    conf
+  end
 
-def cc_command(opt="")
-  conf = RbConfig::CONFIG.merge('hdrdir' => $hdrdir.quote, 'srcdir' => $srcdir.quote,
-                                'arch_hdrdir' => $arch_hdrdir.quote,
-                                'top_srcdir' => $top_srcdir.quote)
-  RbConfig::expand("$(CC) #$INCFLAGS #$CPPFLAGS #$CFLAGS #$ARCH_FLAG #{opt} -c #{CONFTEST_C}",
-                   conf)
-end
+  def link_command(ldflags, *opts)
+    conf = link_config(ldflags, *opts)
+    RbConfig::expand(TRY_LINK.dup, conf)
+  end
 
-def cpp_command(outfile, opt="")
-  conf = RbConfig::CONFIG.merge('hdrdir' => $hdrdir.quote, 'srcdir' => $srcdir.quote,
-                                'arch_hdrdir' => $arch_hdrdir.quote,
-                                'top_srcdir' => $top_srcdir.quote)
-  RbConfig::expand("$(CPP) #$INCFLAGS #$CPPFLAGS #$CFLAGS #{opt} #{CONFTEST_C} #{outfile}",
-                   conf)
-end
+  def cc_config(opt="")
+    conf = RbConfig::CONFIG.merge('hdrdir' => $hdrdir.quote, 'srcdir' => $srcdir.quote,
+                                  'arch_hdrdir' => $arch_hdrdir.quote,
+                                  'top_srcdir' => $top_srcdir.quote)
+    conf
+  end
 
-def libpathflag(libpath=$DEFLIBPATH|$LIBPATH)
-  libpath.map{|x|
-    case x
-    when "$(topdir)", /\A\./
-      LIBPATHFLAG
-    else
-      LIBPATHFLAG+RPATHFLAG
-    end % x.quote
-  }.join
-end
+  def cc_command(opt="")
+    conf = cc_config(opt)
+    RbConfig::expand("$(CC) #$INCFLAGS #$CPPFLAGS #$CFLAGS #$ARCH_FLAG #{opt} -c #{CONFTEST_C}",
+                     conf)
+  end
 
-def with_werror(opt, opts = nil)
-  if opts
-    if opts[:werror] and config_string("WERRORFLAG") {|flag| opt = opt ? "#{opt} #{flag}" : flag}
-      (opts = opts.dup).delete(:werror)
+  def cpp_config(opt)
+    conf = cc_config(opt)
+    if $universal and (arch_flag = conf['ARCH_FLAG']) and !arch_flag.empty?
+      conf['ARCH_FLAG'] = arch_flag.gsub(/(?:\G|\s)-arch\s+\S+/, '')
     end
+    conf
+  end
+
+  def cpp_command(outfile, opt="")
+    conf = cpp_config(opt)
+    RbConfig::expand("$(CPP) #$INCFLAGS #$CPPFLAGS #$CFLAGS #{opt} #{CONFTEST_C} #{outfile}",
+                     conf)
+  end
+
+  def libpathflag(libpath=$DEFLIBPATH|$LIBPATH)
+    libpathflags = nil
+    libpath.map{|x|
+      case x
+      when "$(topdir)", /\A\./
+        LIBPATHFLAG
+      else
+        libpathflags ||= [LIBPATHFLAG, RPATHFLAG].grep(/\S/).join(" ")
+      end % x.quote
+    }.join(" ")
+  end
+
+  def werror_flag(opt = nil)
+    config_string("WERRORFLAG") {|flag| opt = opt && !opt.empty? ? "#{opt} #{flag}" : flag}
+    opt
+  end
+
+  def with_werror(opt, opts = nil)
+    opt = werror_flag(opt) if opts and (opts = opts.dup).delete(:werror)
     yield(opt, opts)
-  else
-    yield(opt)
   end
-end
 
-# :nodoc:
-def try_link0(src, opt="", *opts, &b)
-  cmd = link_command("", opt)
-  if $universal
-    require 'tmpdir'
-    Dir.mktmpdir("mkmf_", oldtmpdir = ENV["TMPDIR"]) do |tmpdir|
-      begin
-        ENV["TMPDIR"] = tmpdir
-        try_do(src, cmd, *opts, &b)
-      ensure
-        ENV["TMPDIR"] = oldtmpdir
+  def try_link0(src, opt = "", ldflags: "", **opts, &b) # :nodoc:
+    exe = CONFTEST+$EXEEXT
+    cmd = link_command(ldflags, opt)
+    if $universal
+      require 'tmpdir'
+      Dir.mktmpdir("mkmf_", oldtmpdir = ENV["TMPDIR"]) do |tmpdir|
+        begin
+          ENV["TMPDIR"] = tmpdir
+          try_do(src, cmd, **opts, &b)
+        ensure
+          ENV["TMPDIR"] = oldtmpdir
+        end
       end
+    else
+      try_do(src, cmd, **opts, &b)
+    end and File.executable?(exe) or return nil
+    exe
+  ensure
+    MakeMakefile.rm_rf(*Dir["#{CONFTEST}*"]-[exe])
+  end
+
+  # Returns whether or not the +src+ can be compiled as a C source and linked
+  # with its depending libraries successfully.  +opt+ is passed to the linker
+  # as options. Note that <tt>$CFLAGS</tt> and <tt>$LDFLAGS</tt> are also
+  # passed to the linker.
+  #
+  # If a block given, it is called with the source before compilation. You can
+  # modify the source in the block.
+  #
+  # [+src+] a String which contains a C source
+  # [+opt+] a String which contains linker options
+  def try_link(src, opt = "", **opts, &b)
+    exe = try_link0(src, opt, **opts, &b) or return false
+    MakeMakefile.rm_f exe
+    true
+  end
+
+  # Returns whether or not the +src+ can be compiled as a C source.  +opt+ is
+  # passed to the C compiler as options. Note that <tt>$CFLAGS</tt> is also
+  # passed to the compiler.
+  #
+  # If a block given, it is called with the source before compilation. You can
+  # modify the source in the block.
+  #
+  # [+src+] a String which contains a C source
+  # [+opt+] a String which contains compiler options
+  def try_compile(src, opt = "", werror: nil, **opts, &b)
+    opt = werror_flag(opt) if werror
+    try_do(src, cc_command(opt), werror: werror, **opts, &b) and
+      File.file?("#{CONFTEST}.#{$OBJEXT}")
+  ensure
+    MakeMakefile.rm_f "#{CONFTEST}*"
+  end
+
+  # Returns whether or not the +src+ can be preprocessed with the C
+  # preprocessor.  +opt+ is passed to the preprocessor as options. Note that
+  # <tt>$CFLAGS</tt> is also passed to the preprocessor.
+  #
+  # If a block given, it is called with the source before preprocessing. You
+  # can modify the source in the block.
+  #
+  # [+src+] a String which contains a C source
+  # [+opt+] a String which contains preprocessor options
+  def try_cpp(src, opt = "", **opts, &b)
+    try_do(src, cpp_command(CPPOUTFILE, opt), **opts, &b) and
+      File.file?("#{CONFTEST}.i")
+  ensure
+    MakeMakefile.rm_f "#{CONFTEST}*"
+  end
+
+  alias try_header try_compile
+
+  def cpp_include(header)
+    if header
+      header = [header] unless header.kind_of? Array
+      header.map {|h| String === h ? "#include <#{h}>\n" : h}.join
+    else
+      ""
     end
-  else
-    try_do(src, cmd, *opts, &b)
   end
-end
 
-# Returns whether or not the +src+ can be compiled as a C source and
-# linked with its depending libraries successfully.
-# +opt+ is passed to the linker as options. Note that +$CFLAGS+ and +$LDFLAGS+
-# are also passed to the linker.
-#
-# If a block given, it is called with the source before compilation. You can
-# modify the source in the block.
-#
-# [+src+] a String which contains a C source
-# [+opt+] a String which contains linker options
-def try_link(src, opt="", *opts, &b)
-  try_link0(src, opt, *opts, &b)
-ensure
-  rm_f "conftest*", "c0x32*"
-end
+  # :startdoc:
 
-# Returns whether or not the +src+ can be compiled as a C source.
-# +opt+ is passed to the C compiler as options. Note that +$CFLAGS+ is
-# also passed to the compiler.
-#
-# If a block given, it is called with the source before compilation. You can
-# modify the source in the block.
-#
-# [+src+] a String which contains a C source
-# [+opt+] a String which contains compiler options
-def try_compile(src, opt="", *opts, &b)
-  with_werror(opt, *opts) {|_opt, *_opts| try_do(src, cc_command(_opt), *_opts, &b)}
-ensure
-  rm_f "conftest*"
-end
+  # Sets <tt>$CPPFLAGS</tt> to _flags_ and yields.  If the block returns a
+  # falsy value, <tt>$CPPFLAGS</tt> is reset to its previous value, remains
+  # set to _flags_ otherwise.
+  #
+  # [+flags+] a C preprocessor flag as a +String+
+  #
+  def with_cppflags(flags)
+    cppflags = $CPPFLAGS
+    $CPPFLAGS = flags.dup
+    ret = yield
+  ensure
+    $CPPFLAGS = cppflags unless ret
+  end
 
-# Returns whether or not the +src+ can be preprocessed with the C preprocessor.
-# +opt+ is passed to the preprocessor as options. Note that +$CFLAGS+ is
-# also passed to the preprocessor.
-#
-# If a block given, it is called with the source before preprocessing. You can
-# modify the source in the block.
-#
-# [+src+] a String which contains a C source
-# [+opt+] a String which contains preprocessor options
-def try_cpp(src, opt="", *opts, &b)
-  try_do(src, cpp_command(CPPOUTFILE, opt), *opts, &b)
-ensure
-  rm_f "conftest*"
-end
+  # :nodoc:
+  def try_cppflags(flags, werror: true, **opts)
+    try_header(MAIN_DOES_NOTHING, flags, werror: werror, **opts)
+  end
 
-class Object
-  alias_method :try_header, (config_string('try_header') || :try_cpp)
-end
+  # Check whether each given C preprocessor flag is acceptable and append it
+  # to <tt>$CPPFLAGS</tt> if so.
+  #
+  # [+flags+] a C preprocessor flag as a +String+ or an +Array+ of them
+  #
+  def append_cppflags(flags, **opts)
+    Array(flags).each do |flag|
+      if checking_for("whether #{flag} is accepted as CPPFLAGS") {
+           try_cppflags(flag, **opts)
+         }
+        $CPPFLAGS << " " << flag
+      end
+    end
+  end
 
-def cpp_include(header)
-  if header
-    header = [header] unless header.kind_of? Array
-    header.map {|h| String === h ? "#include <#{h}>\n" : h}.join
-  else
-    ""
+  # Sets <tt>$CFLAGS</tt> to _flags_ and yields.  If the block returns a falsy
+  # value, <tt>$CFLAGS</tt> is reset to its previous value, remains set to
+  # _flags_ otherwise.
+  def with_cflags(flags)
+    cflags = $CFLAGS
+    $CFLAGS = flags.dup
+    ret = yield
+  ensure
+    $CFLAGS = cflags unless ret
   end
-end
 
-def with_cppflags(flags)
-  cppflags = $CPPFLAGS
-  $CPPFLAGS = flags
-  ret = yield
-ensure
-  $CPPFLAGS = cppflags unless ret
-end
+  # :nodoc:
+  def try_cflags(flags, werror: true, **opts)
+    try_compile(MAIN_DOES_NOTHING, flags, werror: werror, **opts)
+  end
 
-def with_cflags(flags)
-  cflags = $CFLAGS
-  $CFLAGS = flags
-  ret = yield
-ensure
-  $CFLAGS = cflags unless ret
-end
+  # Sets <tt>$LDFLAGS</tt> to _flags_ and yields.  If the block returns a
+  # falsy value, <tt>$LDFLAGS</tt> is reset to its previous value, remains set
+  # to _flags_ otherwise.
+  def with_ldflags(flags)
+    ldflags = $LDFLAGS
+    $LDFLAGS = flags.dup
+    ret = yield
+  ensure
+    $LDFLAGS = ldflags unless ret
+  end
 
-def with_ldflags(flags)
-  ldflags = $LDFLAGS
-  $LDFLAGS = flags
-  ret = yield
-ensure
-  $LDFLAGS = ldflags unless ret
-end
+  # :nodoc:
+  def try_ldflags(flags, werror: $mswin, **opts)
+    try_link(MAIN_DOES_NOTHING, "", ldflags: flags, werror: werror, **opts)
+  end
+
+  # :startdoc:
 
-def try_static_assert(expr, headers = nil, opt = "", &b)
-  headers = cpp_include(headers)
-  try_compile(<<SRC, opt, &b)
+  # Check whether each given linker flag is acceptable and append it to
+  # <tt>$LDFLAGS</tt> if so.
+  #
+  # [+flags+] a linker flag as a +String+ or an +Array+ of them
+  #
+  def append_ldflags(flags, **opts)
+    Array(flags).each do |flag|
+      if checking_for("whether #{flag} is accepted as LDFLAGS") {
+           try_ldflags(flag, **opts)
+         }
+        $LDFLAGS << " " << flag
+      end
+    end
+  end
+
+  # :stopdoc:
+
+  def try_static_assert(expr, headers = nil, opt = "", &b)
+    headers = cpp_include(headers)
+    try_compile(<<SRC, opt, &b)
 #{headers}
 /*top*/
 int conftest_const[(#{expr}) ? 1 : -1];
 SRC
-end
+  end
 
-def try_constant(const, headers = nil, opt = "", &b)
-  includes = cpp_include(headers)
-  if CROSS_COMPILING
-    if try_static_assert("#{const} > 0", headers, opt)
-      # positive constant
-    elsif try_static_assert("#{const} < 0", headers, opt)
-      neg = true
-      const = "-(#{const})"
-    elsif try_static_assert("#{const} == 0", headers, opt)
-      return 0
-    else
-      # not a constant
-      return nil
-    end
-    upper = 1
-    lower = 0
-    until try_static_assert("#{const} <= #{upper}", headers, opt)
-      lower = upper
-      upper <<= 1
-    end
-    return nil unless lower
-    while upper > lower + 1
-      mid = (upper + lower) / 2
-      if try_static_assert("#{const} > #{mid}", headers, opt)
-        lower = mid
+  def try_constant(const, headers = nil, opt = "", &b)
+    includes = cpp_include(headers)
+    neg = try_static_assert("#{const} < 0", headers, opt)
+    if CROSS_COMPILING
+      if neg
+        const = "-(#{const})"
+      elsif try_static_assert("#{const} > 0", headers, opt)
+        # positive constant
+      elsif try_static_assert("#{const} == 0", headers, opt)
+        return 0
       else
-        upper = mid
+        # not a constant
+        return nil
       end
-    end
-    upper = -upper if neg
-    return upper
-  else
-    src = %{#{includes}
+      upper = 1
+      until try_static_assert("#{const} <= #{upper}", headers, opt)
+        lower = upper
+        upper <<= 1
+      end
+      return nil unless lower
+      while upper > lower + 1
+        mid = (upper + lower) / 2
+        if try_static_assert("#{const} > #{mid}", headers, opt)
+          lower = mid
+        else
+          upper = mid
+        end
+      end
+      upper = -upper if neg
+      return upper
+    else
+      src = %{#{includes}
 #include <stdio.h>
 /*top*/
-int conftest_const = (int)(#{const});
-int main() {printf("%d\\n", conftest_const); return 0;}
+typedef#{neg ? '' : ' unsigned'}
+#ifdef PRI_LL_PREFIX
+#define PRI_CONFTEST_PREFIX PRI_LL_PREFIX
+LONG_LONG
+#else
+#define PRI_CONFTEST_PREFIX "l"
+long
+#endif
+conftest_type;
+conftest_type conftest_const = (conftest_type)(#{const});
+int main() {printf("%"PRI_CONFTEST_PREFIX"#{neg ? 'd' : 'u'}\\n", conftest_const); return 0;}
 }
-    if try_link0(src, opt, &b)
-      xpopen("./conftest") do |f|
-        return Integer(f.gets)
+      begin
+        if try_link0(src, opt, &b)
+          xpopen("./#{CONFTEST}") do |f|
+            return Integer(f.gets)
+          end
+        end
+      ensure
+        MakeMakefile.rm_f "#{CONFTEST}#{$EXEEXT}"
       end
     end
+    nil
   end
-  nil
-end
 
-# You should use +have_func+ rather than +try_func+.
-#
-# [+func+] a String which contains a symbol name
-# [+libs+] a String which contains library names.
-# [+headers+] a String or an Array of strings which contains
-#             names of header files.
-def try_func(func, libs, headers = nil, &b)
-  headers = cpp_include(headers)
-  case func
-  when /^&/
-    decltype = proc {|x|"const volatile void *#{x}"}
-  else
-    call = true
-    decltype = proc {|x| "void ((*#{x})())"}
-  end
-  try_link(<<"SRC", libs, &b) or
+  # You should use +have_func+ rather than +try_func+.
+  #
+  # [+func+] a String which contains a symbol name
+  # [+libs+] a String which contains library names.
+  # [+headers+] a String or an Array of strings which contains names of header
+  #             files.
+  def try_func(func, libs, headers = nil, opt = "", &b)
+    headers = cpp_include(headers)
+    prepare = String.new
+    case func
+    when /^&/
+      decltype = proc {|x|"const volatile void *#{x}"}
+    when /\)$/
+      strvars = []
+      call = func.gsub(/""/) {
+        v = "s#{strvars.size + 1}"
+        strvars << v
+        v
+      }
+      unless strvars.empty?
+        prepare << "char " << strvars.map {|v| %[#{v}[1024] = ""]}.join(", ") << "; "
+      end
+    when nil
+      call = ""
+    else
+      call = "#{func}()"
+      decltype = proc {|x| "void ((*#{x})())"}
+    end
+    if opt and !opt.empty?
+      [[:to_str], [:join, " "], [:to_s]].each do |meth, *args|
+        if opt.respond_to?(meth)
+          break opt = opt.__send__(meth, *args)
+        end
+      end
+      opt = "#{opt} #{libs}"
+    else
+      opt = libs
+    end
+    decltype && try_link(<<"SRC", opt, &b) or
 #{headers}
 /*top*/
-int t() { #{decltype["volatile p"]}; p = (#{decltype[]})#{func}; return 0; }
-#{MAIN_DOES_NOTHING "t"}
+extern int t(void);
+#{MAIN_DOES_NOTHING 't'}
+int t(void) { #{decltype["volatile p"]}; p = (#{decltype[]})#{func}; return !p; }
 SRC
-  call && try_link(<<"SRC", libs, &b)
+    call && try_link(<<"SRC", opt, &b)
 #{headers}
 /*top*/
-int t() { #{func}(); return 0; }
-#{MAIN_DOES_NOTHING "t"}
+extern int t(void);
+#{MAIN_DOES_NOTHING 't'}
+#{"extern void #{call};" if decltype}
+int t(void) { #{prepare}#{call}; return 0; }
 SRC
-end
+  end
 
-# You should use +have_var+ rather than +try_var+.
-def try_var(var, headers = nil, &b)
-  headers = cpp_include(headers)
-  try_compile(<<"SRC", &b)
+  # You should use +have_var+ rather than +try_var+.
+  def try_var(var, headers = nil, opt = "", &b)
+    headers = cpp_include(headers)
+    try_compile(<<"SRC", opt, &b)
 #{headers}
 /*top*/
-int t() { const volatile void *volatile p; p = &(&#{var})[0]; return 0; }
-#{MAIN_DOES_NOTHING "t"}
+extern int t(void);
+#{MAIN_DOES_NOTHING 't'}
+int t(void) { const volatile void *volatile p; p = &(&#{var})[0]; return !p; }
 SRC
-end
+  end
 
-# Returns whether or not the +src+ can be preprocessed with the C preprocessor and
-# matches with +pat+.
-#
-# If a block given, it is called with the source before compilation. You can
-# modify the source in the block.
-#
-# [+pat+] a Regexp or a String
-# [+src+] a String which contains a C source
-# [+opt+] a String which contains preprocessor options
-#
-# Note:
-#   When pat is a Regexp the matching will be checked in process,
-#   otherwise egrep(1) will be invoked to check it.
-def egrep_cpp(pat, src, opt = "", &b)
-  src = create_tmpsrc(src, &b)
-  xpopen(cpp_command('', opt)) do |f|
-    if Regexp === pat
-      puts("    ruby -ne 'print if #{pat.inspect}'")
-      f.grep(pat) {|l|
-        puts "#{f.lineno}: #{l}"
-        return true
-      }
-      false
-    else
-      puts("    egrep '#{pat}'")
-      begin
-        stdin = $stdin.dup
-        $stdin.reopen(f)
-        system("egrep", pat)
-      ensure
-        $stdin.reopen(stdin)
+  # :startdoc:
+
+  # Returns whether or not the +src+ can be preprocessed with the C
+  # preprocessor and matches with +pat+.
+  #
+  # If a block given, it is called with the source before compilation. You can
+  # modify the source in the block.
+  #
+  # [+pat+] a Regexp or a String
+  # [+src+] a String which contains a C source
+  # [+opt+] a String which contains preprocessor options
+  #
+  # NOTE: When pat is a Regexp the matching will be checked in process,
+  # otherwise egrep(1) will be invoked to check it.
+  def egrep_cpp(pat, src, opt = "", &b)
+    src = create_tmpsrc(src, &b)
+    xpopen(cpp_command('', opt)) do |f|
+      if Regexp === pat
+        puts("    ruby -ne 'print if #{pat.inspect}'")
+        !f.grep(pat) {|l|
+          puts "#{f.lineno}: #{l}"
+        }.empty?
+      else
+        puts("    egrep '#{pat}'")
+        system("egrep", pat, in: f)
       end
     end
+  ensure
+    MakeMakefile.rm_f "#{CONFTEST}*"
+    log_src(src)
   end
-ensure
-  rm_f "conftest*"
-  log_src(src)
-end
 
-# This is used internally by the have_macro? method.
-def macro_defined?(macro, src, opt = "", &b)
-  src = src.sub(/[^\n]\z/, "\\&\n")
-  try_compile(src + <<"SRC", opt, &b)
+  # :stopdoc:
+
+  # This is used internally by the have_macro? method.
+  def macro_defined?(macro, src, opt = "", &b)
+    src = src.sub(/[^\n]\z/, "\\&\n")
+    try_compile(src + <<"SRC", opt, &b)
 /*top*/
 #ifndef #{macro}
 # error
->>>>>> #{macro} undefined <<<<<<
+|:/ === #{macro} undefined === /:|
 #endif
 SRC
-end
-
-# Returns whether or not
-# * the +src+ can be compiled as a C source,
-# * the result object can be linked with its depending libraries successfully,
-# * the linked file can be invoked as an executable
-# * and the executable exits successfully
-# +opt+ is passed to the linker as options. Note that +$CFLAGS+ and +$LDFLAGS+
-# are also passed to the linker.
-#
-# If a block given, it is called with the source before compilation. You can
-# modify the source in the block.
-#
-# [+src+] a String which contains a C source
-# [+opt+] a String which contains linker options
-#
-# @return true when the executable exits successfully, false when it fails, or
-#         nil when preprocessing, compilation or link fails.
-def try_run(src, opt = "", &b)
-  if try_link0(src, opt, &b)
-    xsystem("./conftest")
-  else
-    nil
   end
-ensure
-  rm_f "conftest*"
-end
 
-def install_files(mfile, ifiles, map = nil, srcprefix = nil)
-  ifiles or return
-  ifiles.empty? and return
-  srcprefix ||= "$(srcdir)/#{srcprefix}".chomp('/')
-  RbConfig::expand(srcdir = srcprefix.dup)
-  dirs = []
-  path = Hash.new {|h, i| h[i] = dirs.push([i])[-1]}
-  ifiles.each do |files, dir, prefix|
-    dir = map_dir(dir, map)
-    prefix &&= %r|\A#{Regexp.quote(prefix)}/?|
-    if /\A\.\// =~ files
-      # install files which are in current working directory.
-      files = files[2..-1]
-      len = nil
+  # Returns whether or not:
+  # * the +src+ can be compiled as a C source,
+  # * the result object can be linked with its depending libraries
+  #   successfully,
+  # * the linked file can be invoked as an executable
+  # * and the executable exits successfully
+  #
+  # +opt+ is passed to the linker as options. Note that <tt>$CFLAGS</tt> and
+  # <tt>$LDFLAGS</tt> are also passed to the linker.
+  #
+  # If a block given, it is called with the source before compilation. You can
+  # modify the source in the block.
+  #
+  # [+src+] a String which contains a C source
+  # [+opt+] a String which contains linker options
+  #
+  # Returns true when the executable exits successfully, false when it fails,
+  # or nil when preprocessing, compilation or link fails.
+  def try_run(src, opt = "", &b)
+    raise "cannot run test program while cross compiling" if CROSS_COMPILING
+    if try_link0(src, opt, &b)
+      xsystem("./#{CONFTEST}")
     else
-      # install files which are under the $(srcdir).
-      files = File.join(srcdir, files)
-      len = srcdir.size
-    end
-    f = nil
-    Dir.glob(files) do |fx|
-      f = fx
-      f[0..len] = "" if len
-      case File.basename(f)
-      when *$NONINSTALLFILES
-        next
-      end
-      d = File.dirname(f)
-      d.sub!(prefix, "") if prefix
-      d = (d.empty? || d == ".") ? dir : File.join(dir, d)
-      f = File.join(srcprefix, f) if len
-      path[d] << f
+      nil
     end
-    unless len or f
-      d = File.dirname(files)
-      d.sub!(prefix, "") if prefix
-      d = (d.empty? || d == ".") ? dir : File.join(dir, d)
-      path[d] << files
+  ensure
+    MakeMakefile.rm_f "#{CONFTEST}*"
+  end
+
+  def install_files(mfile, ifiles, map = nil, srcprefix = nil)
+    ifiles or return
+    ifiles.empty? and return
+    srcprefix ||= "$(srcdir)/#{srcprefix}".chomp('/')
+    RbConfig::expand(srcdir = srcprefix.dup)
+    dirs = []
+    path = Hash.new {|h, i| h[i] = dirs.push([i])[-1]}
+    ifiles.each do |files, dir, prefix|
+      dir = map_dir(dir, map)
+      prefix &&= %r|\A#{Regexp.quote(prefix)}/?|
+      if /\A\.\// =~ files
+        # install files which are in current working directory.
+        files = files[2..-1]
+        len = nil
+      else
+        # install files which are under the $(srcdir).
+        files = File.join(srcdir, files)
+        len = srcdir.size
+      end
+      f = nil
+      Dir.glob(files) do |fx|
+        f = fx
+        f[0..len] = "" if len
+        case File.basename(f)
+        when *$NONINSTALLFILES
+          next
+        end
+        d = File.dirname(f)
+        d.sub!(prefix, "") if prefix
+        d = (d.empty? || d == ".") ? dir : File.join(dir, d)
+        f = File.join(srcprefix, f) if len
+        path[d] << f
+      end
+      unless len or f
+        d = File.dirname(files)
+        d.sub!(prefix, "") if prefix
+        d = (d.empty? || d == ".") ? dir : File.join(dir, d)
+        path[d] << files
+      end
     end
+    dirs
   end
-  dirs
-end
 
-def install_rb(mfile, dest, srcdir = nil)
-  install_files(mfile, [["lib/**/*.rb", dest, "lib"]], nil, srcdir)
-end
+  def install_rb(mfile, dest, srcdir = nil)
+    install_files(mfile, [["lib/**/*.rb", dest, "lib"]], nil, srcdir)
+  end
 
-def append_library(libs, lib) # :no-doc:
-  format(LIBARG, lib) + " " + libs
-end
+  def append_library(libs, lib) # :no-doc:
+    format(LIBARG, lib) + " " + libs
+  end
 
-def message(*s)
-  unless Logging.quiet and not $VERBOSE
-    printf(*s)
-    $stdout.flush
+  # Prints messages to $stdout, if verbose mode.
+  #
+  # Internal use only.
+  #
+  def message(*s)
+    unless Logging.quiet and not $VERBOSE
+      printf(*s)
+      $stdout.flush
+    end
   end
-end
 
-# This emits a string to stdout that allows users to see the results of the
-# various have* and find* methods as they are tested.
-#
-# Internal use only.
-#
-def checking_for(m, fmt = nil)
-  f = caller[0][/in `([^<].*)'$/, 1] and f << ": " #` for vim #'
-  m = "checking #{/\Acheck/ =~ f ? '' : 'for '}#{m}... "
-  message "%s", m
-  a = r = nil
-  Logging::postpone do
-    r = yield
-    a = (fmt ? fmt % r : r ? "yes" : "no") << "\n"
-    "#{f}#{m}-------------------- #{a}\n"
-  end
-  message(a)
-  Logging::message "--------------------\n\n"
-  r
-end
+  # This emits a string to stdout that allows users to see the results of the
+  # various have* and find* methods as they are tested.
+  #
+  # Internal use only.
+  #
+  def checking_for(m, fmt = nil)
+    if f = caller_locations(1, 1).first.base_label and /\A\w/ =~ f
+      f += ": "
+    else
+      f = ""
+    end
+    m = "checking #{/\Acheck/ =~ f ? '' : 'for '}#{m}... "
+    message "%s", m
+    a = r = nil
+    Logging::postpone do
+      r = yield
+      a = (fmt ? "#{fmt % r}" : r ? "yes" : "no")
+      "#{f}#{m}-------------------- #{a}\n\n"
+    end
+    message "%s\n", a
+    Logging::message "--------------------\n\n"
+    r
+  end
 
-def checking_message(target, place = nil, opt = nil)
-  [["in", place], ["with", opt]].inject("#{target}") do |msg, (pre, noun)|
-    if noun
-      [[:to_str], [:join, ","], [:to_s]].each do |meth, *args|
-        if noun.respond_to?(meth)
-          break noun = noun.send(meth, *args)
+  # Build a message for checking.
+  #
+  # Internal use only.
+  #
+  def checking_message(target, place = nil, opt = nil)
+    [["in", place], ["with", opt]].inject("#{target}") do |msg, (pre, noun)|
+      if noun
+        [[:to_str], [:join, ","], [:to_s]].each do |meth, *args|
+          if noun.respond_to?(meth)
+            break noun = noun.__send__(meth, *args)
+          end
+        end
+        unless noun.empty?
+          msg << " #{pre} " unless msg.empty?
+          msg << noun
         end
       end
-      msg << " #{pre} #{noun}" unless noun.empty?
+      msg
     end
-    msg
   end
-end
 
-# :startdoc:
+  # :startdoc:
 
-# Returns whether or not +macro+ is defined either in the common header
-# files or within any +headers+ you provide.
-#
-# Any options you pass to +opt+ are passed along to the compiler.
-#
-def have_macro(macro, headers = nil, opt = "", &b)
-  checking_for checking_message(macro, headers, opt) do
-    macro_defined?(macro, cpp_include(headers), opt, &b)
+  # Check whether each given C compiler flag is acceptable and append it
+  # to <tt>$CFLAGS</tt> if so.
+  #
+  # [+flags+] a C compiler flag as a +String+ or an +Array+ of them
+  #
+  def append_cflags(flags, **opts)
+    Array(flags).each do |flag|
+      if checking_for("whether #{flag} is accepted as CFLAGS") {
+           try_cflags(flag, **opts)
+         }
+        $CFLAGS << " " << flag
+      end
+    end
   end
-end
 
-# Returns whether or not the given entry point +func+ can be found within
-# +lib+.  If +func+ is nil, the 'main()' entry point is used by default.
-# If found, it adds the library to list of libraries to be used when linking
-# your extension.
-#
-# If +headers+ are provided, it will include those header files as the
-# header files it looks in when searching for +func+.
-#
-# The real name of the library to be linked can be altered by
-# '--with-FOOlib' configuration option.
-#
-def have_library(lib, func = nil, headers = nil, &b)
-  func = "main" if !func or func.empty?
-  lib = with_config(lib+'lib', lib)
-  checking_for checking_message("#{func}()", LIBARG%lib) do
-    if COMMON_LIBS.include?(lib)
-      true
-    else
-      libs = append_library($libs, lib)
-      if try_func(func, libs, headers, &b)
-        $libs = libs
+  # Returns whether or not +macro+ is defined either in the common header
+  # files or within any +headers+ you provide.
+  #
+  # Any options you pass to +opt+ are passed along to the compiler.
+  #
+  def have_macro(macro, headers = nil, opt = "", &b)
+    checking_for checking_message(macro, headers, opt) do
+      macro_defined?(macro, cpp_include(headers), opt, &b)
+    end
+  end
+
+  # Returns whether or not the given entry point +func+ can be found within
+  # +lib+.  If +func+ is +nil+, the <code>main()</code> entry point is used by
+  # default.  If found, it adds the library to list of libraries to be used
+  # when linking your extension.
+  #
+  # If +headers+ are provided, it will include those header files as the
+  # header files it looks in when searching for +func+.
+  #
+  # The real name of the library to be linked can be altered by
+  # <code>--with-FOOlib</code> configuration option.
+  #
+  def have_library(lib, func = nil, headers = nil, opt = "", &b)
+    dir_config(lib)
+    lib = with_config(lib+'lib', lib)
+    checking_for checking_message(func && func.funcall_style, LIBARG%lib, opt) do
+      if COMMON_LIBS.include?(lib)
         true
       else
-        false
+        libs = append_library($libs, lib)
+        if try_func(func, libs, headers, opt, &b)
+          $libs = libs
+          true
+        else
+          false
+        end
       end
     end
   end
-end
 
-# Returns whether or not the entry point +func+ can be found within the library
-# +lib+ in one of the +paths+ specified, where +paths+ is an array of strings.
-# If +func+ is nil , then the main() function is used as the entry point.
-#
-# If +lib+ is found, then the path it was found on is added to the list of
-# library paths searched and linked against.
-#
-def find_library(lib, func, *paths, &b)
-  func = "main" if !func or func.empty?
-  lib = with_config(lib+'lib', lib)
-  paths = paths.collect {|path| path.split(File::PATH_SEPARATOR)}.flatten
-  checking_for "#{func}() in #{LIBARG%lib}" do
-    libpath = $LIBPATH
-    libs = append_library($libs, lib)
-    begin
-      until r = try_func(func, libs, &b) or paths.empty?
-        $LIBPATH = libpath | [paths.shift]
-      end
-      if r
-        $libs = libs
-        libpath = nil
+  # Returns whether or not the entry point +func+ can be found within the
+  # library +lib+ in one of the +paths+ specified, where +paths+ is an array
+  # of strings.  If +func+ is +nil+ , then the <code>main()</code> function is
+  # used as the entry point.
+  #
+  # If +lib+ is found, then the path it was found on is added to the list of
+  # library paths searched and linked against.
+  #
+  def find_library(lib, func, *paths, &b)
+    dir_config(lib)
+    lib = with_config(lib+'lib', lib)
+    paths = paths.flat_map {|path| path.split(File::PATH_SEPARATOR)}
+    checking_for checking_message(func && func.funcall_style, LIBARG%lib) do
+      libpath = $LIBPATH
+      libs = append_library($libs, lib)
+      begin
+        until r = try_func(func, libs, &b) or paths.empty?
+          $LIBPATH = libpath | [paths.shift]
+        end
+        if r
+          $libs = libs
+          libpath = nil
+        end
+      ensure
+        $LIBPATH = libpath if libpath
       end
-    ensure
-      $LIBPATH = libpath if libpath
+      r
     end
-    r
   end
-end
 
-# Returns whether or not the function +func+ can be found in the common
-# header files, or within any +headers+ that you provide.  If found, a
-# macro is passed as a preprocessor constant to the compiler using the
-# function name, in uppercase, prepended with 'HAVE_'.
-#
-# For example, if have_func('foo') returned true, then the HAVE_FOO
-# preprocessor macro would be passed to the compiler.
-#
-def have_func(func, headers = nil, &b)
-  checking_for checking_message("#{func}()", headers) do
-    if try_func(func, $libs, headers, &b)
-      $defs.push(format("-DHAVE_%s", func.tr_cpp))
-      true
-    else
-      false
+  # Returns whether or not the function +func+ can be found in the common
+  # header files, or within any +headers+ that you provide.  If found, a macro
+  # is passed as a preprocessor constant to the compiler using the function
+  # name, in uppercase, prepended with +HAVE_+.
+  #
+  # To check functions in an additional library, you need to check that
+  # library first using <code>have_library()</code>.  The +func+ shall be
+  # either mere function name or function name with arguments.
+  #
+  # For example, if <code>have_func('foo')</code> returned +true+, then the
+  # +HAVE_FOO+ preprocessor macro would be passed to the compiler.
+  #
+  def have_func(func, headers = nil, opt = "", &b)
+    checking_for checking_message(func.funcall_style, headers, opt) do
+      if try_func(func, $libs, headers, opt, &b)
+        $defs << "-DHAVE_#{func.sans_arguments.tr_cpp}"
+        true
+      else
+        false
+      end
     end
   end
-end
 
-# Returns whether or not the variable +var+ can be found in the common
-# header files, or within any +headers+ that you provide.  If found, a
-# macro is passed as a preprocessor constant to the compiler using the
-# variable name, in uppercase, prepended with 'HAVE_'.
-#
-# For example, if have_var('foo') returned true, then the HAVE_FOO
-# preprocessor macro would be passed to the compiler.
-#
-def have_var(var, headers = nil, &b)
-  checking_for checking_message(var, headers) do
-    if try_var(var, headers, &b)
-      $defs.push(format("-DHAVE_%s", var.tr_cpp))
-      true
-    else
-      false
+  # Returns whether or not the variable +var+ can be found in the common
+  # header files, or within any +headers+ that you provide.  If found, a macro
+  # is passed as a preprocessor constant to the compiler using the variable
+  # name, in uppercase, prepended with +HAVE_+.
+  #
+  # To check variables in an additional library, you need to check that
+  # library first using <code>have_library()</code>.
+  #
+  # For example, if <code>have_var('foo')</code> returned true, then the
+  # +HAVE_FOO+ preprocessor macro would be passed to the compiler.
+  #
+  def have_var(var, headers = nil, opt = "", &b)
+    checking_for checking_message(var, headers, opt) do
+      if try_var(var, headers, opt, &b)
+        $defs.push(format("-DHAVE_%s", var.tr_cpp))
+        true
+      else
+        false
+      end
     end
   end
-end
 
-# Returns whether or not the given +header+ file can be found on your system.
-# If found, a macro is passed as a preprocessor constant to the compiler using
-# the header file name, in uppercase, prepended with 'HAVE_'.
-#
-# For example, if have_header('foo.h') returned true, then the HAVE_FOO_H
-# preprocessor macro would be passed to the compiler.
-#
-def have_header(header, preheaders = nil, &b)
-  checking_for header do
-    if try_header(cpp_include(preheaders)+cpp_include(header), &b)
-      $defs.push(format("-DHAVE_%s", header.tr_cpp))
-      true
-    else
-      false
+  # Returns whether or not the given +header+ file can be found on your system.
+  # If found, a macro is passed as a preprocessor constant to the compiler
+  # using the header file name, in uppercase, prepended with +HAVE_+.
+  #
+  # For example, if <code>have_header('foo.h')</code> returned true, then the
+  # +HAVE_FOO_H+ preprocessor macro would be passed to the compiler.
+  #
+  def have_header(header, preheaders = nil, opt = "", &b)
+    dir_config(header[/.*?(?=\/)|.*?(?=\.)/])
+    checking_for header do
+      if try_header(cpp_include(preheaders)+cpp_include(header), opt, &b)
+        $defs.push(format("-DHAVE_%s", header.tr_cpp))
+        true
+      else
+        false
+      end
     end
   end
-end
 
-# Returns whether or not the given +framework+ can be found on your system.
-# If found, a macro is passed as a preprocessor constant to the compiler
-# using the framework name, in uppercase, prepended with +HAVE_FRAMEWORK_+.
-#
-# For example, if <code>have_framework('Ruby')</code> returned true, then
-# the +HAVE_FRAMEWORK_RUBY+ preprocessor macro would be passed to the
-# compiler.
-#
-# If +fw+ is a pair of the framework name and its header file name
-# that header file is checked, instead of the normally used header
-# file which is named same as the framework.
-def have_framework(fw, &b)
-  if Array === fw
-    fw, header = *fw
-  else
-    header = "#{fw}.h"
-  end
-  checking_for fw do
-    src = cpp_include("#{fw}/#{header}") << "\n" "int main(void){return 0;}"
-    opt = " -framework #{fw}"
-    if try_link(src, "-ObjC#{opt}", &b)
-      $defs.push(format("-DHAVE_FRAMEWORK_%s", fw.tr_cpp))
-      # TODO: non-worse way than this hack, to get rid of separating
-      # option and its argument.
-      $LDFLAGS << " -ObjC" unless /(\A|\s)-ObjC(\s|\z)/ =~ $LDFLAGS
-      $LDFLAGS << opt
-      true
+  # Returns whether or not the given +framework+ can be found on your system.
+  # If found, a macro is passed as a preprocessor constant to the compiler
+  # using the framework name, in uppercase, prepended with +HAVE_FRAMEWORK_+.
+  #
+  # For example, if <code>have_framework('Ruby')</code> returned true, then
+  # the +HAVE_FRAMEWORK_RUBY+ preprocessor macro would be passed to the
+  # compiler.
+  #
+  # If +fw+ is a pair of the framework name and its header file name
+  # that header file is checked, instead of the normally used header
+  # file which is named same as the framework.
+  def have_framework(fw, &b)
+    if Array === fw
+      fw, header = *fw
     else
-      false
+      header = "#{fw}.h"
+    end
+    checking_for fw do
+      src = cpp_include("#{fw}/#{header}") << "\n" "int main(void){return 0;}"
+      opt = " -framework #{fw}"
+      if try_link(src, opt, &b) or (objc = try_link(src, "-ObjC#{opt}", &b))
+        $defs.push(format("-DHAVE_FRAMEWORK_%s", fw.tr_cpp))
+        # TODO: non-worse way than this hack, to get rid of separating
+        # option and its argument.
+        $LDFLAGS << " -ObjC" if objc and /(\A|\s)-ObjC(\s|\z)/ !~ $LDFLAGS
+        $LIBS << opt
+        true
+      else
+        false
+      end
     end
   end
-end
 
-# Instructs mkmf to search for the given +header+ in any of the +paths+
-# provided, and returns whether or not it was found in those paths.
-#
-# If the header is found then the path it was found on is added to the list
-# of included directories that are sent to the compiler (via the -I switch).
-#
-def find_header(header, *paths)
-  message = checking_message(header, paths)
-  header = cpp_include(header)
-  checking_for message do
-    if try_header(header)
-      true
-    else
-      found = false
-      paths.each do |dir|
-        opt = "-I#{dir}".quote
-        if try_header(header, opt)
-          $INCFLAGS << " " << opt
-          found = true
-          break
+  # Instructs mkmf to search for the given +header+ in any of the +paths+
+  # provided, and returns whether or not it was found in those paths.
+  #
+  # If the header is found then the path it was found on is added to the list
+  # of included directories that are sent to the compiler (via the
+  # <code>-I</code> switch).
+  #
+  def find_header(header, *paths)
+    message = checking_message(header, paths)
+    header = cpp_include(header)
+    checking_for message do
+      if try_header(header)
+        true
+      else
+        found = false
+        paths.each do |dir|
+          opt = "-I#{dir}".quote
+          if try_header(header, opt)
+            $INCFLAGS << " " << opt
+            found = true
+            break
+          end
         end
+        found
       end
-      found
     end
   end
-end
 
-# Returns whether or not the struct of type +type+ contains +member+.  If
-# it does not, or the struct type can't be found, then false is returned.  You
-# may optionally specify additional +headers+ in which to look for the struct
-# (in addition to the common header files).
-#
-# If found, a macro is passed as a preprocessor constant to the compiler using
-# the type name and the member name, in uppercase, prepended with 'HAVE_'.
-#
-# For example, if have_struct_member('struct foo', 'bar') returned true, then the
-# HAVE_STRUCT_FOO_BAR preprocessor macro would be passed to the compiler.
-#
-# HAVE_ST_BAR is also defined for backward compatibility.
-#
-def have_struct_member(type, member, headers = nil, &b)
-  checking_for checking_message("#{type}.#{member}", headers) do
-    if try_compile(<<"SRC", &b)
+  # Returns whether or not the struct of type +type+ contains +member+.  If
+  # it does not, or the struct type can't be found, then false is returned.
+  # You may optionally specify additional +headers+ in which to look for the
+  # struct (in addition to the common header files).
+  #
+  # If found, a macro is passed as a preprocessor constant to the compiler
+  # using the type name and the member name, in uppercase, prepended with
+  # +HAVE_+.
+  #
+  # For example, if <code>have_struct_member('struct foo', 'bar')</code>
+  # returned true, then the +HAVE_STRUCT_FOO_BAR+ preprocessor macro would be
+  # passed to the compiler.
+  #
+  # +HAVE_ST_BAR+ is also defined for backward compatibility.
+  #
+  def have_struct_member(type, member, headers = nil, opt = "", &b)
+    checking_for checking_message("#{type}.#{member}", headers) do
+      if try_compile(<<"SRC", opt, &b)
 #{cpp_include(headers)}
 /*top*/
 int s = (char *)&((#{type}*)0)->#{member} - (char *)0;
-#{MAIN_DOES_NOTHING "s"}
+#{MAIN_DOES_NOTHING}
 SRC
-      $defs.push(format("-DHAVE_%s_%s", type.tr_cpp, member.tr_cpp))
-      $defs.push(format("-DHAVE_ST_%s", member.tr_cpp)) # backward compatibility
-      true
-    else
-      false
+        $defs.push(format("-DHAVE_%s_%s", type.tr_cpp, member.tr_cpp))
+        $defs.push(format("-DHAVE_ST_%s", member.tr_cpp)) # backward compatibility
+        true
+      else
+        false
+      end
     end
   end
-end
 
-# Returns whether or not the static type +type+ is defined.
-#
-# See also +have_type+
-#
-def try_type(type, headers = nil, opt = "", &b)
-  if try_compile(<<"SRC", opt, &b)
+  # :nodoc:
+  # Returns whether or not the static type +type+ is defined.
+  #
+  # See also +have_type+
+  #
+  def try_type(type, headers = nil, opt = "", &b)
+    if try_compile(<<"SRC", opt, &b)
 #{cpp_include(headers)}
 /*top*/
 typedef #{type} conftest_type;
 int conftestval[sizeof(conftest_type)?1:-1];
 SRC
-    $defs.push(format("-DHAVE_TYPE_%s", type.tr_cpp))
-    true
-  else
-    false
+      $defs.push(format("-DHAVE_TYPE_%s", type.tr_cpp))
+      true
+    else
+      false
+    end
   end
-end
 
-# Returns whether or not the static type +type+ is defined.  You may
-# optionally pass additional +headers+ to check against in addition to the
-# common header files.
-#
-# You may also pass additional flags to +opt+ which are then passed along to
-# the compiler.
-#
-# If found, a macro is passed as a preprocessor constant to the compiler using
-# the type name, in uppercase, prepended with 'HAVE_TYPE_'.
-#
-# For example, if have_type('foo') returned true, then the HAVE_TYPE_FOO
-# preprocessor macro would be passed to the compiler.
-#
-def have_type(type, headers = nil, opt = "", &b)
-  checking_for checking_message(type, headers, opt) do
-    try_type(type, headers, opt, &b)
+  # Returns whether or not the static type +type+ is defined.  You may
+  # optionally pass additional +headers+ to check against in addition to the
+  # common header files.
+  #
+  # You may also pass additional flags to +opt+ which are then passed along to
+  # the compiler.
+  #
+  # If found, a macro is passed as a preprocessor constant to the compiler
+  # using the type name, in uppercase, prepended with +HAVE_TYPE_+.
+  #
+  # For example, if <code>have_type('foo')</code> returned true, then the
+  # +HAVE_TYPE_FOO+ preprocessor macro would be passed to the compiler.
+  #
+  def have_type(type, headers = nil, opt = "", &b)
+    checking_for checking_message(type, headers, opt) do
+      try_type(type, headers, opt, &b)
+    end
   end
-end
 
-# Returns where the static type +type+ is defined.
-#
-# You may also pass additional flags to +opt+ which are then passed along to
-# the compiler.
-#
-# See also +have_type+.
-#
-def find_type(type, opt, *headers, &b)
-  opt ||= ""
-  fmt = "not found"
-  def fmt.%(x)
-    x ? x.respond_to?(:join) ? x.join(",") : x : self
-  end
-  checking_for checking_message(type, nil, opt), fmt do
-    headers.find do |h|
-      try_type(type, h, opt, &b)
+  # Returns where the static type +type+ is defined.
+  #
+  # You may also pass additional flags to +opt+ which are then passed along to
+  # the compiler.
+  #
+  # See also +have_type+.
+  #
+  def find_type(type, opt, *headers, &b)
+    opt ||= ""
+    fmt = "not found"
+    def fmt.%(x)
+      x ? x.respond_to?(:join) ? x.join(",") : x : self
+    end
+    checking_for checking_message(type, nil, opt), fmt do
+      headers.find do |h|
+        try_type(type, h, opt, &b)
+      end
     end
   end
-end
 
-# Returns whether or not the Constant +const+ is defined.
-#
-# See also +have_const+
-#
-def try_const(const, headers = nil, opt = "", &b)
-  const, type = *const
-  if try_compile(<<"SRC", opt, &b)
+  # :nodoc:
+  # Returns whether or not the constant +const+ is defined.
+  #
+  # See also +have_const+
+  #
+  def try_const(const, headers = nil, opt = "", &b)
+    const, type = *const
+    if try_compile(<<"SRC", opt, &b)
 #{cpp_include(headers)}
 /*top*/
 typedef #{type || 'int'} conftest_type;
 conftest_type conftestval = #{type ? '' : '(int)'}#{const};
 SRC
-    $defs.push(format("-DHAVE_CONST_%s", const.tr_cpp))
-    true
-  else
-    false
+      $defs.push(format("-DHAVE_CONST_%s", const.tr_cpp))
+      true
+    else
+      false
+    end
   end
-end
 
-# Returns whether or not the constant +const+ is defined.  You may
-# optionally pass the +type+ of +const+ as <code>[const, type]</code>,
-# like as:
-#
-#   have_const(%w[PTHREAD_MUTEX_INITIALIZER pthread_mutex_t], "pthread.h")
-#
-# You may also pass additional +headers+ to check against in addition
-# to the common header files, and additional flags to +opt+ which are
-# then passed along to the compiler.
-#
-# If found, a macro is passed as a preprocessor constant to the compiler using
-# the type name, in uppercase, prepended with 'HAVE_CONST_'.
-#
-# For example, if have_const('foo') returned true, then the HAVE_CONST_FOO
-# preprocessor macro would be passed to the compiler.
-#
-def have_const(const, headers = nil, opt = "", &b)
-  checking_for checking_message([*const].compact.join(' '), headers, opt) do
-    try_const(const, headers, opt, &b)
+  # Returns whether or not the constant +const+ is defined.  You may
+  # optionally pass the +type+ of +const+ as <code>[const, type]</code>,
+  # such as:
+  #
+  #   have_const(%w[PTHREAD_MUTEX_INITIALIZER pthread_mutex_t], "pthread.h")
+  #
+  # You may also pass additional +headers+ to check against in addition to the
+  # common header files, and additional flags to +opt+ which are then passed
+  # along to the compiler.
+  #
+  # If found, a macro is passed as a preprocessor constant to the compiler
+  # using the type name, in uppercase, prepended with +HAVE_CONST_+.
+  #
+  # For example, if <code>have_const('foo')</code> returned true, then the
+  # +HAVE_CONST_FOO+ preprocessor macro would be passed to the compiler.
+  #
+  def have_const(const, headers = nil, opt = "", &b)
+    checking_for checking_message([*const].compact.join(' '), headers, opt) do
+      try_const(const, headers, opt, &b)
+    end
   end
-end
-
-STRING_OR_FAILED_FORMAT = "%s"
-# :stopdoc:
-def STRING_OR_FAILED_FORMAT.%(x)
-  x ? super : "failed"
-end
 
-def typedef_expr(type, headers)
-  typename, member = type.split('.', 2)
-  prelude = cpp_include(headers).split(/$/)
-  prelude << "typedef #{typename} rbcv_typedef_;\n"
-  return "rbcv_typedef_", member, prelude
-end
+  # :stopdoc:
+  STRING_OR_FAILED_FORMAT = "%s"
+  class << STRING_OR_FAILED_FORMAT # :nodoc:
+    def %(x)
+      x ? super : "failed"
+    end
+  end
 
-def try_signedness(type, member, headers = nil, opts = nil, &b)
-  raise ArgumentError, "don't know how to tell signedness of members" if member
-  if try_static_assert("(#{type})-1 < 0", headers, opts)
-    return -1
-  elsif try_static_assert("(#{type})-1 > 0", headers, opts)
-    return +1
+  def typedef_expr(type, headers)
+    typename, member = type.split('.', 2)
+    prelude = cpp_include(headers).split(/$/)
+    prelude << "typedef #{typename} rbcv_typedef_;\n"
+    return "rbcv_typedef_", member, prelude
   end
-end
 
-# :startdoc:
-
-# Returns the size of the given +type+.  You may optionally specify additional
-# +headers+ to search in for the +type+.
-#
-# If found, a macro is passed as a preprocessor constant to the compiler using
-# the type name, in uppercase, prepended with 'SIZEOF_', followed by the type
-# name, followed by '=X' where 'X' is the actual size.
-#
-# For example, if check_sizeof('mystruct') returned 12, then the
-# SIZEOF_MYSTRUCT=12 preprocessor macro would be passed to the compiler.
-#
-def check_sizeof(type, headers = nil, opts = "", &b)
-  typedef, member, prelude = typedef_expr(type, headers)
-  prelude << "static #{typedef} *rbcv_ptr_;\n"
-  prelude = [prelude]
-  expr = "sizeof((*rbcv_ptr_)#{"." << member if member})"
-  fmt = STRING_OR_FAILED_FORMAT
-  checking_for checking_message("size of #{type}", headers), fmt do
-    if size = try_constant(expr, prelude, opts, &b)
-      $defs.push(format("-DSIZEOF_%s=%s", type.tr_cpp, size))
-      size
+  def try_signedness(type, member, headers = nil, opts = nil)
+    raise ArgumentError, "don't know how to tell signedness of members" if member
+    if try_static_assert("(#{type})-1 < 0", headers, opts)
+      return -1
+    elsif try_static_assert("(#{type})-1 > 0", headers, opts)
+      return +1
     end
   end
-end
 
-# Returns the signedness of the given +type+.  You may optionally
-# specify additional +headers+ to search in for the +type+.
-#
-# If the +type+ is found and is a numeric type, a macro is passed as a
-# preprocessor constant to the compiler using the +type+ name, in
-# uppercase, prepended with 'SIGNEDNESS_OF_', followed by the +type+
-# name, followed by '=X' where 'X' is positive integer if the +type+ is
-# unsigned, or negative integer if the +type+ is signed.
-#
-# For example, if size_t is defined as unsigned, then
-# check_signedness('size_t') would returned +1 and the
-# SIGNEDNESS_OF_SIZE_T=+1 preprocessor macro would be passed to the
-# compiler, and SIGNEDNESS_OF_INT=-1 if check_signedness('int') is
-# done.
-#
-def check_signedness(type, headers = nil, opts = nil, &b)
-  typedef, member, prelude = typedef_expr(type, headers)
-  signed = nil
-  checking_for("signedness of #{type}", STRING_OR_FAILED_FORMAT) do
-    signed = try_signedness(typedef, member, [prelude], opts, &b) or next nil
-    $defs.push("-DSIGNEDNESS_OF_%s=%+d" % [type.tr_cpp, signed])
-    signed < 0 ? "signed" : "unsigned"
-  end
-  signed
-end
+  # :startdoc:
+
+  # Returns the size of the given +type+.  You may optionally specify
+  # additional +headers+ to search in for the +type+.
+  #
+  # If found, a macro is passed as a preprocessor constant to the compiler
+  # using the type name, in uppercase, prepended with +SIZEOF_+, followed by
+  # the type name, followed by <code>=X</code> where "X" is the actual size.
+  #
+  # For example, if <code>check_sizeof('mystruct')</code> returned 12, then
+  # the <code>SIZEOF_MYSTRUCT=12</code> preprocessor macro would be passed to
+  # the compiler.
+  #
+  def check_sizeof(type, headers = nil, opts = "", &b)
+    typedef, member, prelude = typedef_expr(type, headers)
+    prelude << "#{typedef} *rbcv_ptr_;\n"
+    prelude = [prelude]
+    expr = "sizeof((*rbcv_ptr_)#{"." << member if member})"
+    fmt = STRING_OR_FAILED_FORMAT
+    checking_for checking_message("size of #{type}", headers), fmt do
+      if size = try_constant(expr, prelude, opts, &b)
+        $defs.push(format("-DSIZEOF_%s=%s", type.tr_cpp, size))
+        size
+      end
+    end
+  end
 
-# Returns the convertible integer type of the given +type+.  You may
-# optionally specify additional +headers+ to search in for the +type+.
-# _Convertible_ means actually same type, or typedefed from same type.
-#
-# If the +type+ is a integer type and _convertible_ type is found,
-# following macros are passed as preprocessor constants to the
-# compiler using the +type+ name, in uppercase.
-#
-# * 'TYPEOF_', followed by the +type+ name, followed by '=X' where 'X'
-#   is the found _convertible_ type name.  * 'TYP2NUM' and 'NUM2TYP,
-#   where 'TYP' is the +type+ name in uppercase with replacing '_t'
-#   suffix with 'T', followed by '=X' where 'X' is the macro name to
-#   convert +type+ to +Integer+ object, and vice versa.
-#
-# For example, if foobar_t is defined as unsigned long, then
-# convertible_int("foobar_t") would return "unsigned long", and define
-# macros:
-#
-#   #define TYPEOF_FOOBAR_T unsigned long
-#   #define FOOBART2NUM ULONG2NUM
-#   #define NUM2FOOBART NUM2ULONG
-def convertible_int(type, headers = nil, opts = nil, &b)
-  type, macname = *type
-  checking_for("convertible type of #{type}", STRING_OR_FAILED_FORMAT) do
-    if UNIVERSAL_INTS.include?(type)
-      type
-    else
-      typedef, member, prelude = typedef_expr(type, headers, &b)
-      next unless signed = try_signedness(typedef, member, [prelude])
-      u = "unsigned " if signed > 0
-      prelude << "extern rbcv_typedef_ foo();"
-      compat = UNIVERSAL_INTS.find {|t|
-        try_compile([prelude, "extern #{u}#{t} foo();"].join("\n"), opts, :werror=>true, &b)
-      }
-      if compat
-        macname ||= type.sub(/_(?=t\z)/, '').tr_cpp
-        conv = (compat == "long long" ? "LL" : compat.upcase)
-        compat = "#{u}#{compat}"
-        $defs.push(format("-DTYPEOF_%s=%s", type.tr_cpp, compat.quote))
-        $defs.push(format("-DPRI_%s_PREFIX=PRI_%s_PREFIX", macname, conv))
-        conv = (u ? "U" : "") + conv
-        $defs.push(format("-D%s2NUM=%s2NUM", macname, conv))
-        $defs.push(format("-DNUM2%s=NUM2%s", macname, conv))
-        compat
+  # Returns the signedness of the given +type+.  You may optionally specify
+  # additional +headers+ to search in for the +type+.
+  #
+  # If the +type+ is found and is a numeric type, a macro is passed as a
+  # preprocessor constant to the compiler using the +type+ name, in uppercase,
+  # prepended with +SIGNEDNESS_OF_+, followed by the +type+ name, followed by
+  # <code>=X</code> where "X" is positive integer if the +type+ is unsigned
+  # and a negative integer if the +type+ is signed.
+  #
+  # For example, if +size_t+ is defined as unsigned, then
+  # <code>check_signedness('size_t')</code> would return +1 and the
+  # <code>SIGNEDNESS_OF_SIZE_T=+1</code> preprocessor macro would be passed to
+  # the compiler.  The <code>SIGNEDNESS_OF_INT=-1</code> macro would be set
+  # for <code>check_signedness('int')</code>
+  #
+  def check_signedness(type, headers = nil, opts = nil, &b)
+    typedef, member, prelude = typedef_expr(type, headers)
+    signed = nil
+    checking_for("signedness of #{type}", STRING_OR_FAILED_FORMAT) do
+      signed = try_signedness(typedef, member, [prelude], opts, &b) or next nil
+      $defs.push("-DSIGNEDNESS_OF_%s=%+d" % [type.tr_cpp, signed])
+      signed < 0 ? "signed" : "unsigned"
+    end
+    signed
+  end
+
+  # Returns the convertible integer type of the given +type+.  You may
+  # optionally specify additional +headers+ to search in for the +type+.
+  # _convertible_ means actually the same type, or typedef'd from the same
+  # type.
+  #
+  # If the +type+ is an integer type and the _convertible_ type is found,
+  # the following macros are passed as preprocessor constants to the compiler
+  # using the +type+ name, in uppercase.
+  #
+  # * +TYPEOF_+, followed by the +type+ name, followed by <code>=X</code>
+  #   where "X" is the found _convertible_ type name.
+  # * +TYP2NUM+ and +NUM2TYP+,
+  #   where +TYP+ is the +type+ name in uppercase with replacing an +_t+
+  #   suffix with "T", followed by <code>=X</code> where "X" is the macro name
+  #   to convert +type+ to an Integer object, and vice versa.
+  #
+  # For example, if +foobar_t+ is defined as unsigned long, then
+  # <code>convertible_int("foobar_t")</code> would return "unsigned long", and
+  # define these macros:
+  #
+  #   #define TYPEOF_FOOBAR_T unsigned long
+  #   #define FOOBART2NUM ULONG2NUM
+  #   #define NUM2FOOBART NUM2ULONG
+  #
+  def convertible_int(type, headers = nil, opts = nil, &b)
+    type, macname = *type
+    checking_for("convertible type of #{type}", STRING_OR_FAILED_FORMAT) do
+      if UNIVERSAL_INTS.include?(type)
+        type
+      else
+        typedef, member, prelude = typedef_expr(type, headers, &b)
+        if member
+          prelude << "static rbcv_typedef_ rbcv_var;"
+          compat = UNIVERSAL_INTS.find {|t|
+            try_static_assert("sizeof(rbcv_var.#{member}) == sizeof(#{t})", [prelude], opts, &b)
+          }
+        else
+          next unless signed = try_signedness(typedef, member, [prelude])
+          u = "unsigned " if signed > 0
+          prelude << "extern rbcv_typedef_ foo();"
+          compat = UNIVERSAL_INTS.find {|t|
+            try_compile([prelude, "extern #{u}#{t} foo();"].join("\n"), opts, werror: true, &b)
+          }
+        end
+        if compat
+          macname ||= type.sub(/_(?=t\z)/, '').tr_cpp
+          conv = (compat == "long long" ? "LL" : compat.upcase)
+          compat = "#{u}#{compat}"
+          typename = type.tr_cpp
+          $defs.push(format("-DSIZEOF_%s=SIZEOF_%s", typename, compat.tr_cpp))
+          $defs.push(format("-DTYPEOF_%s=%s", typename, compat.quote))
+          $defs.push(format("-DPRI_%s_PREFIX=PRI_%s_PREFIX", macname, conv))
+          conv = (u ? "U" : "") + conv
+          $defs.push(format("-D%s2NUM=%s2NUM", macname, conv))
+          $defs.push(format("-DNUM2%s=NUM2%s", macname, conv))
+          compat
+        end
       end
     end
   end
-end
-# :stopdoc:
+  # :stopdoc:
 
-# Used internally by the what_type? method to determine if +type+ is a scalar
-# pointer.
-def scalar_ptr_type?(type, member = nil, headers = nil, &b)
-  try_compile(<<"SRC", &b)   # pointer
+  # Used internally by the what_type? method to determine if +type+ is a scalar
+  # pointer.
+  def scalar_ptr_type?(type, member = nil, headers = nil, &b)
+    try_compile(<<"SRC", &b)
 #{cpp_include(headers)}
 /*top*/
 volatile #{type} conftestval;
-int t() {return (int)(1-*(conftestval#{member ? ".#{member}" : ""}));}
-#{MAIN_DOES_NOTHING "t"}
+extern int t(void);
+#{MAIN_DOES_NOTHING 't'}
+int t(void) {return (int)(1-*(conftestval#{member ? ".#{member}" : ""}));}
 SRC
-end
+  end
 
-# Used internally by the what_type? method to determine if +type+ is a scalar
-# pointer.
-def scalar_type?(type, member = nil, headers = nil, &b)
-  try_compile(<<"SRC", &b)   # pointer
+  # Used internally by the what_type? method to determine if +type+ is a scalar
+  # pointer.
+  def scalar_type?(type, member = nil, headers = nil, &b)
+    try_compile(<<"SRC", &b)
 #{cpp_include(headers)}
 /*top*/
 volatile #{type} conftestval;
-int t() {return (int)(1-(conftestval#{member ? ".#{member}" : ""}));}
-#{MAIN_DOES_NOTHING "t"}
+extern int t(void);
+#{MAIN_DOES_NOTHING 't'}
+int t(void) {return (int)(1-(conftestval#{member ? ".#{member}" : ""}));}
 SRC
-end
+  end
 
-# Used internally by the what_type? method to check if _typeof_ GCC
-# extension is available.
-def have_typeof?
-  return $typeof if defined?($typeof)
-  $typeof = %w[__typeof__ typeof].find do |t|
-    try_compile(<<SRC)
+  # Used internally by the what_type? method to check if the _typeof_ GCC
+  # extension is available.
+  def have_typeof?
+    return $typeof if defined?($typeof)
+    $typeof = %w[__typeof__ typeof].find do |t|
+      try_compile(<<SRC)
 int rbcv_foo;
 #{t}(rbcv_foo) rbcv_bar;
 SRC
+    end
   end
-end
 
-def what_type?(type, member = nil, headers = nil, &b)
-  m = "#{type}"
-  var = val = "*rbcv_var_"
-  func = "rbcv_func_(void)"
-  if member
-    m << "." << member
-  else
-    type, member = type.split('.', 2)
-  end
-  if member
-    val = "(#{var}).#{member}"
-  end
-  prelude = [cpp_include(headers).split(/^/)]
-  prelude << ["typedef #{type} rbcv_typedef_;\n",
-              "extern rbcv_typedef_ *#{func};\n",
-              "static rbcv_typedef_ #{var};\n",
-             ]
-  type = "rbcv_typedef_"
-  fmt = member && !(typeof = have_typeof?) ? "seems %s" : "%s"
-  if typeof
-    var = "*rbcv_member_"
-    func = "rbcv_mem_func_(void)"
-    member = nil
-    type = "rbcv_mem_typedef_"
-    prelude[-1] << "typedef #{typeof}(#{val}) #{type};\n"
-    prelude[-1] << "extern #{type} *#{func};\n"
-    prelude[-1] << "static #{type} #{var};\n"
-    val = var
-  end
-  def fmt.%(x)
-    x ? super : "unknown"
-  end
-  checking_for checking_message(m, headers), fmt do
-    if scalar_ptr_type?(type, member, prelude, &b)
-      if try_static_assert("sizeof(*#{var}) == 1", prelude)
-        return "string"
-      end
-      ptr = "*"
-    elsif scalar_type?(type, member, prelude, &b)
-      unless member and !typeof or try_static_assert("(#{type})-1 < 0", prelude)
-        unsigned = "unsigned"
-      end
-      ptr = ""
+  # :startdoc:
+
+  # Returns a string represents the type of _type_, or _member_ of
+  # _type_ if _member_ is not +nil+.
+  def what_type?(type, member = nil, headers = nil, &b)
+    m = "#{type}"
+    var = val = "*rbcv_var_"
+    func = "rbcv_func_(void)"
+    if member
+      m << "." << member
     else
-      next
+      type, member = type.split('.', 2)
+    end
+    if member
+      val = "(#{var}).#{member}"
     end
-    type = UNIVERSAL_INTS.find do |t|
-      pre = prelude
-      unless member
-        pre += [["static #{unsigned} #{t} #{ptr}#{var};\n",
-                 "extern #{unsigned} #{t} #{ptr}*#{func};\n"]]
+    prelude = [cpp_include(headers).split(/^/)]
+    prelude << ["typedef #{type} rbcv_typedef_;\n",
+                "extern rbcv_typedef_ *#{func};\n",
+                "rbcv_typedef_ #{var};\n",
+               ]
+    type = "rbcv_typedef_"
+    fmt = member && !(typeof = have_typeof?) ? "seems %s" : "%s"
+    if typeof
+      var = "*rbcv_member_"
+      func = "rbcv_mem_func_(void)"
+      member = nil
+      type = "rbcv_mem_typedef_"
+      prelude[-1] << "typedef #{typeof}(#{val}) #{type};\n"
+      prelude[-1] << "extern #{type} *#{func};\n"
+      prelude[-1] << "#{type} #{var};\n"
+      val = var
+    end
+    def fmt.%(x)
+      x ? super : "unknown"
+    end
+    checking_for checking_message(m, headers), fmt do
+      if scalar_ptr_type?(type, member, prelude, &b)
+        if try_static_assert("sizeof(*#{var}) == 1", prelude)
+          return "string"
+        end
+        ptr = "*"
+      elsif scalar_type?(type, member, prelude, &b)
+        unless member and !typeof or try_static_assert("(#{type})-1 < 0", prelude)
+          unsigned = "unsigned"
+        end
+        ptr = ""
+      else
+        next
+      end
+      type = UNIVERSAL_INTS.find do |t|
+        pre = prelude
+        unless member
+          pre += [["#{unsigned} #{t} #{ptr}#{var};\n",
+                   "extern #{unsigned} #{t} #{ptr}*#{func};\n"]]
+        end
+        try_static_assert("sizeof(#{ptr}#{val}) == sizeof(#{unsigned} #{t})", pre)
       end
-      try_static_assert("sizeof(#{ptr}#{val}) == sizeof(#{unsigned} #{t})", pre)
+      type or next
+      [unsigned, type, ptr].join(" ").strip
     end
-    type or next
-    [unsigned, type, ptr].join(" ").strip
   end
-end
 
-# This method is used internally by the find_executable method.
-#
-# Internal use only.
-#
-def find_executable0(bin, path = nil)
-  executable_file = proc do |name|
-    begin
-      stat = File.stat(name)
-    rescue SystemCallError
-    else
-      next name if stat.file? and stat.executable?
+  # :nodoc:
+  #
+  # This method is used internally by the find_executable method.
+  #
+  # Internal use only.
+  #
+  def find_executable0(bin, path = nil)
+    executable_file = proc do |name|
+      begin
+        stat = File.stat(name)
+      rescue SystemCallError
+      else
+        next name if stat.file? and stat.executable?
+      end
     end
-  end
 
-  exts = config_string('EXECUTABLE_EXTS') {|s| s.split} || config_string('EXEEXT') {|s| [s]}
-  if File.expand_path(bin) == bin
-    return bin if executable_file.call(bin)
-    if exts
-      exts.each {|ext| executable_file.call(file = bin + ext) and return file}
+    exts = config_string('EXECUTABLE_EXTS') {|s| s.split} || config_string('EXEEXT') {|s| [s]}
+    if File.expand_path(bin) == bin
+      return bin if executable_file.call(bin)
+      if exts
+        exts.each {|ext| executable_file.call(file = bin + ext) and return file}
+      end
+      return nil
     end
-    return nil
-  end
-  if path ||= ENV['PATH']
-    path = path.split(File::PATH_SEPARATOR)
-  else
-    path = %w[/usr/local/bin /usr/ucb /usr/bin /bin]
-  end
-  file = nil
-  path.each do |dir|
-    return file if executable_file.call(file = File.join(dir, bin))
-    if exts
-      exts.each {|ext| executable_file.call(ext = file + ext) and return ext}
+    if path ||= ENV['PATH']
+      path = path.split(File::PATH_SEPARATOR)
+    else
+      path = %w[/usr/local/bin /usr/ucb /usr/bin /bin]
     end
+    file = nil
+    path.each do |dir|
+      dir.sub!(/\A"(.*)"\z/m, '\1') if $mswin or $mingw
+      return file if executable_file.call(file = File.join(dir, bin))
+      if exts
+        exts.each {|ext| executable_file.call(ext = file + ext) and return ext}
+      end
+    end
+    nil
   end
-  nil
-end
 
-# :startdoc:
-
-# Searches for the executable +bin+ on +path+. The default path is your
-# PATH environment variable. If that isn't defined, it will resort to
-# searching /usr/local/bin, /usr/ucb, /usr/bin and /bin.
-#
-# If found, it will return the full path, including the executable name,
-# of where it was found.
-#
-# Note that this method does not actually affect the generated Makefile.
-#
-def find_executable(bin, path = nil)
-  checking_for checking_message(bin, path) do
-    find_executable0(bin, path)
+  # Searches for the executable +bin+ on +path+.  The default path is your
+  # +PATH+ environment variable. If that isn't defined, it will resort to
+  # searching /usr/local/bin, /usr/ucb, /usr/bin and /bin.
+  #
+  # If found, it will return the full path, including the executable name, of
+  # where it was found.
+  #
+  # Note that this method does not actually affect the generated Makefile.
+  #
+  def find_executable(bin, path = nil)
+    checking_for checking_message(bin, path) do
+      find_executable0(bin, path)
+    end
   end
-end
 
-# :stopdoc:
+  # :stopdoc:
 
-def arg_config(config, default=nil, &block)
-  $arg_config << [config, default]
-  defaults = []
-  if default
-    defaults << default
-  elsif !block
-    defaults << nil
+  def arg_config(config, default=nil, &block)
+    $arg_config << [config, default]
+    defaults = []
+    if default
+      defaults << default
+    elsif !block
+      defaults << nil
+    end
+    $configure_args.fetch(config.tr('_', '-'), *defaults, &block)
+  end
+
+  # :startdoc:
+
+  # Tests for the presence of a <tt>--with-</tt>_config_ or
+  # <tt>--without-</tt>_config_ option.  Returns +true+ if the with option is
+  # given, +false+ if the without option is given, and the default value
+  # otherwise.
+  #
+  # This can be useful for adding custom definitions, such as debug
+  # information.
+  #
+  # Example:
+  #
+  #    if with_config("debug")
+  #       $defs.push("-DOSSL_DEBUG") unless $defs.include? "-DOSSL_DEBUG"
+  #    end
+  #
+  def with_config(config, default=nil)
+    config = config.sub(/^--with[-_]/, '')
+    val = arg_config("--with-"+config) do
+      if arg_config("--without-"+config)
+        false
+      elsif block_given?
+        yield(config, default)
+      else
+        break default
+      end
+    end
+    case val
+    when "yes"
+      true
+    when "no"
+      false
+    else
+      val
+    end
   end
-  $configure_args.fetch(config.tr('_', '-'), *defaults, &block)
-end
 
-# :startdoc:
-
-# Tests for the presence of a --with-<tt>config</tt> or --without-<tt>config</tt>
-# option. Returns true if the with option is given, false if the without
-# option is given, and the default value otherwise.
-#
-# This can be useful for adding custom definitions, such as debug information.
-#
-# Example:
-#
-#    if with_config("debug")
-#       $defs.push("-DOSSL_DEBUG") unless $defs.include? "-DOSSL_DEBUG"
-#    end
-#
-def with_config(config, default=nil)
-  config = config.sub(/^--with[-_]/, '')
-  val = arg_config("--with-"+config) do
-    if arg_config("--without-"+config)
+  # Tests for the presence of an <tt>--enable-</tt>_config_ or
+  # <tt>--disable-</tt>_config_ option. Returns +true+ if the enable option is
+  # given, +false+ if the disable option is given, and the default value
+  # otherwise.
+  #
+  # This can be useful for adding custom definitions, such as debug
+  # information.
+  #
+  # Example:
+  #
+  #    if enable_config("debug")
+  #       $defs.push("-DOSSL_DEBUG") unless $defs.include? "-DOSSL_DEBUG"
+  #    end
+  #
+  def enable_config(config, default=nil)
+    if arg_config("--enable-"+config)
+      true
+    elsif arg_config("--disable-"+config)
       false
     elsif block_given?
       yield(config, default)
     else
-      break default
+      return default
     end
   end
-  case val
-  when "yes"
-    true
-  when "no"
-    false
-  else
-    val
-  end
-end
 
-# Tests for the presence of an --enable-<tt>config</tt> or
-# --disable-<tt>config</tt> option. Returns true if the enable option is given,
-# false if the disable option is given, and the default value otherwise.
-#
-# This can be useful for adding custom definitions, such as debug information.
-#
-# Example:
-#
-#    if enable_config("debug")
-#       $defs.push("-DOSSL_DEBUG") unless $defs.include? "-DOSSL_DEBUG"
-#    end
-#
-def enable_config(config, default=nil)
-  if arg_config("--enable-"+config)
-    true
-  elsif arg_config("--disable-"+config)
-    false
-  elsif block_given?
-    yield(config, default)
-  else
-    return default
-  end
-end
+  # Generates a header file consisting of the various macro definitions
+  # generated by other methods such as have_func and have_header. These are
+  # then wrapped in a custom <code>#ifndef</code> based on the +header+ file
+  # name, which defaults to "extconf.h".
+  #
+  # For example:
+  #
+  #   # extconf.rb
+  #   require 'mkmf'
+  #   have_func('realpath')
+  #   have_header('sys/utime.h')
+  #   create_header
+  #   create_makefile('foo')
+  #
+  # The above script would generate the following extconf.h file:
+  #
+  #   #ifndef EXTCONF_H
+  #   #define EXTCONF_H
+  #   #define HAVE_REALPATH 1
+  #   #define HAVE_SYS_UTIME_H 1
+  #   #endif
+  #
+  # Given that the create_header method generates a file based on definitions
+  # set earlier in your extconf.rb file, you will probably want to make this
+  # one of the last methods you call in your script.
+  #
+  def create_header(header = "extconf.h")
+    message "creating %s\n", header
+    sym = header.tr_cpp
+    hdr = ["#ifndef #{sym}\n#define #{sym}\n"]
+    for line in $defs
+      case line
+      when /^-D([^=]+)(?:=(.*))?/
+        hdr << "#define #$1 #{$2 ? Shellwords.shellwords($2)[0].gsub(/(?=\t+)/, "\\\n") : 1}\n"
+      when /^-U(.*)/
+        hdr << "#undef #$1\n"
+      end
+    end
+    hdr << "#endif\n"
+    hdr = hdr.join("")
+    log_src(hdr, "#{header} is")
+    unless (File.read(header) == hdr rescue false)
+      File.open(header, "wb") do |hfile|
+        hfile.write(hdr)
+      end
+    end
+    $extconf_h = header
+  end
+
+  # call-seq:
+  #   dir_config(target)
+  #   dir_config(target, prefix)
+  #   dir_config(target, idefault, ldefault)
+  #
+  # Sets a +target+ name that the user can then use to configure
+  # various "with" options with on the command line by using that
+  # name.  For example, if the target is set to "foo", then the user
+  # could use the <code>--with-foo-dir=prefix</code>,
+  # <code>--with-foo-include=dir</code> and
+  # <code>--with-foo-lib=dir</code> command line options to tell where
+  # to search for header/library files.
+  #
+  # You may pass along additional parameters to specify default
+  # values.  If one is given it is taken as default +prefix+, and if
+  # two are given they are taken as "include" and "lib" defaults in
+  # that order.
+  #
+  # In any case, the return value will be an array of determined
+  # "include" and "lib" directories, either of which can be nil if no
+  # corresponding command line option is given when no default value
+  # is specified.
+  #
+  # Note that dir_config only adds to the list of places to search for
+  # libraries and include files.  It does not link the libraries into your
+  # application.
+  #
+  def dir_config(target, idefault=nil, ldefault=nil)
+    key = [target, idefault, ldefault].compact.join("\0")
+    if conf = $config_dirs[key]
+      return conf
+    end
 
-# Generates a header file consisting of the various macro definitions generated
-# by other methods such as have_func and have_header. These are then wrapped in
-# a custom #ifndef based on the +header+ file name, which defaults to
-# 'extconf.h'.
-#
-# For example:
-#
-#    # extconf.rb
-#    require 'mkmf'
-#    have_func('realpath')
-#    have_header('sys/utime.h')
-#    create_header
-#    create_makefile('foo')
-#
-# The above script would generate the following extconf.h file:
-#
-#    #ifndef EXTCONF_H
-#    #define EXTCONF_H
-#    #define HAVE_REALPATH 1
-#    #define HAVE_SYS_UTIME_H 1
-#    #endif
-#
-# Given that the create_header method generates a file based on definitions
-# set earlier in your extconf.rb file, you will probably want to make this
-# one of the last methods you call in your script.
-#
-def create_header(header = "extconf.h")
-  message "creating %s\n", header
-  sym = header.tr_cpp
-  hdr = ["#ifndef #{sym}\n#define #{sym}\n"]
-  for line in $defs
-    case line
-    when /^-D([^=]+)(?:=(.*))?/
-      hdr << "#define #$1 #{$2 ? Shellwords.shellwords($2)[0].gsub(/(?=\t+)/, "\\\n") : 1}\n"
-    when /^-U(.*)/
-      hdr << "#undef #$1\n"
-    end
-  end
-  hdr << "#endif\n"
-  hdr = hdr.join
-  log_src(hdr, "#{header} is")
-  unless (IO.read(header) == hdr rescue false)
-    open(header, "wb") do |hfile|
-      hfile.write(hdr)
-    end
-  end
-  $extconf_h = header
-end
+    if dir = with_config(target + "-dir", (idefault unless ldefault))
+      defaults = Array === dir ? dir : dir.split(File::PATH_SEPARATOR)
+      idefault = ldefault = nil
+    end
+
+    idir = with_config(target + "-include", idefault)
+    if conf = $arg_config.assoc("--with-#{target}-include")
+      conf[1] ||= "${#{target}-dir}/include"
+    end
+    ldir = with_config(target + "-lib", ldefault)
+    if conf = $arg_config.assoc("--with-#{target}-lib")
+      conf[1] ||= "${#{target}-dir}/#{_libdir_basename}"
+    end
 
-# Sets a +target+ name that the user can then use to configure various 'with'
-# options with on the command line by using that name.  For example, if the
-# target is set to "foo", then the user could use the --with-foo-dir command
-# line option.
-#
-# You may pass along additional 'include' or 'lib' defaults via the +idefault+
-# and +ldefault+ parameters, respectively.
-#
-# Note that dir_config only adds to the list of places to search for libraries
-# and include files.  It does not link the libraries into your application.
-#
-def dir_config(target, idefault=nil, ldefault=nil)
-  if dir = with_config(target + "-dir", (idefault unless ldefault))
-    defaults = Array === dir ? dir : dir.split(File::PATH_SEPARATOR)
-    idefault = ldefault = nil
-  end
-
-  idir = with_config(target + "-include", idefault)
-  $arg_config.last[1] ||= "${#{target}-dir}/include"
-  ldir = with_config(target + "-lib", ldefault)
-  $arg_config.last[1] ||= "${#{target}-dir}/#{@libdir_basename}"
-
-  idirs = idir ? Array === idir ? idir.dup : idir.split(File::PATH_SEPARATOR) : []
-  if defaults
-    idirs.concat(defaults.collect {|d| d + "/include"})
-    idir = ([idir] + idirs).compact.join(File::PATH_SEPARATOR)
-  end
-  unless idirs.empty?
-    idirs.collect! {|d| "-I" + d}
-    idirs -= Shellwords.shellwords($CPPFLAGS)
+    idirs = idir ? Array === idir ? idir.dup : idir.split(File::PATH_SEPARATOR) : []
+    if defaults
+      idirs.concat(defaults.collect {|d| d + "/include"})
+      idir = ([idir] + idirs).compact.join(File::PATH_SEPARATOR)
+    end
     unless idirs.empty?
-      $CPPFLAGS = (idirs.quote << $CPPFLAGS).join(" ")
+      idirs.collect! {|d| "-I" + d}
+      idirs -= Shellwords.shellwords($CPPFLAGS)
+      unless idirs.empty?
+        $CPPFLAGS = (idirs.quote << $CPPFLAGS).join(" ")
+      end
     end
-  end
 
-  ldirs = ldir ? Array === ldir ? ldir.dup : ldir.split(File::PATH_SEPARATOR) : []
-  if defaults
-      ldirs.concat(defaults.collect {|d| "#{d}/#{@libdir_basename}"})
-    ldir = ([ldir] + ldirs).compact.join(File::PATH_SEPARATOR)
-  end
-  $LIBPATH = ldirs | $LIBPATH
+    ldirs = ldir ? Array === ldir ? ldir.dup : ldir.split(File::PATH_SEPARATOR) : []
+    if defaults
+      ldirs.concat(defaults.collect {|d| "#{d}/#{_libdir_basename}"})
+      ldir = ([ldir] + ldirs).compact.join(File::PATH_SEPARATOR)
+    end
+    $LIBPATH = ldirs | $LIBPATH
+
+    $config_dirs[key] = [idir, ldir]
+  end
+
+  # Returns compile/link information about an installed library in a tuple of <code>[cflags,
+  # ldflags, libs]</code>, by using the command found first in the following commands:
+  #
+  # 1. If <code>--with-{pkg}-config={command}</code> is given via
+  #    command line option: <code>{command} {options}</code>
+  #
+  # 2. <code>{pkg}-config {options}</code>
+  #
+  # 3. <code>pkg-config {options} {pkg}</code>
+  #
+  # Where +options+ is the option name without dashes, for instance <code>"cflags"</code> for the
+  # <code>--cflags</code> flag.
+  #
+  # The values obtained are appended to <code>$INCFLAGS</code>, <code>$CFLAGS</code>,
+  # <code>$LDFLAGS</code> and <code>$libs</code>.
+  #
+  # If one or more <code>options</code> argument is given, the config command is
+  # invoked with the options and a stripped output string is returned without
+  # modifying any of the global values mentioned above.
+  def pkg_config(pkg, *options)
+    fmt = "not found"
+    def fmt.%(x)
+      x ? x.inspect : self
+    end
 
-  [idir, ldir]
-end
+    checking_for "pkg-config for #{pkg}", fmt do
+      _, ldir = dir_config(pkg)
+      if ldir
+        pkg_config_path = "#{ldir}/pkgconfig"
+        if File.directory?(pkg_config_path)
+          Logging.message("PKG_CONFIG_PATH = %s\n", pkg_config_path)
+          envs = ["PKG_CONFIG_PATH"=>[pkg_config_path, ENV["PKG_CONFIG_PATH"]].compact.join(File::PATH_SEPARATOR)]
+        end
+      end
+      if pkgconfig = with_config("#{pkg}-config") and find_executable0(pkgconfig)
+      # if and only if package specific config command is given
+      elsif ($PKGCONFIG ||=
+             (pkgconfig = with_config("pkg-config") {config_string("PKG_CONFIG") || ENV["PKG_CONFIG"] || "pkg-config"}) &&
+             find_executable0(pkgconfig) && pkgconfig) and
+           xsystem([*envs, $PKGCONFIG, "--exists", pkg])
+        # default to pkg-config command
+        pkgconfig = $PKGCONFIG
+        args = [pkg]
+      elsif find_executable0(pkgconfig = "#{pkg}-config")
+      # default to package specific config command, as a last resort.
+      else
+        pkgconfig = nil
+      end
+      if pkgconfig
+        get = proc {|opts|
+          opts = Array(opts).map { |o| "--#{o}" }
+          opts = xpopen([*envs, pkgconfig, *opts, *args], err:[:child, :out], &:read)
+          Logging.open {puts opts.each_line.map{|s|"=> #{s.inspect}"}}
+          if $?.success?
+            opts = opts.strip
+            libarg, libpath = LIBARG, LIBPATHFLAG.strip
+            opts = opts.shellsplit.map { |s|
+              if s.start_with?('-l')
+                libarg % s[2..]
+              elsif s.start_with?('-L')
+                libpath % s[2..]
+              else
+                s
+              end
+            }.quote.join(" ")
+            opts
+          end
+        }
+      end
+      orig_ldflags = $LDFLAGS
+      if get and !options.empty?
+        get[options]
+      elsif get and try_ldflags(ldflags = get['libs'])
+        if incflags = get['cflags-only-I']
+          $INCFLAGS << " " << incflags
+          cflags = get['cflags-only-other']
+        else
+          cflags = get['cflags']
+        end
+        libs = get['libs-only-l']
+        if cflags
+          $CFLAGS += " " << cflags
+          $CXXFLAGS += " " << cflags
+        end
+        if libs
+          ldflags = (Shellwords.shellwords(ldflags) - Shellwords.shellwords(libs)).quote.join(" ")
+        else
+          libs, ldflags = Shellwords.shellwords(ldflags).partition {|s| s =~ /-l([^ ]+)/ }.map {|l|l.quote.join(" ")}
+        end
+        $libs += " " << libs
 
-# :stopdoc:
-
-# Handles meta information about installed libraries. Uses your platform's
-# pkg-config program if it has one.
-def pkg_config(pkg)
-  if pkgconfig = with_config("#{pkg}-config") and find_executable0(pkgconfig)
-    # iff package specific config command is given
-    get = proc {|opt| `#{pkgconfig} --#{opt}`.chomp}
-  elsif ($PKGCONFIG ||=
-         (pkgconfig = with_config("pkg-config", ("pkg-config" unless CROSS_COMPILING))) &&
-         find_executable0(pkgconfig) && pkgconfig) and
-      system("#{$PKGCONFIG} --exists #{pkg}")
-    # default to pkg-config command
-    get = proc {|opt| `#{$PKGCONFIG} --#{opt} #{pkg}`.chomp}
-  elsif find_executable0(pkgconfig = "#{pkg}-config")
-    # default to package specific config command, as a last resort.
-    get = proc {|opt| `#{pkgconfig} --#{opt}`.chomp}
-  end
-  if get
-    cflags = get['cflags']
-    ldflags = get['libs']
-    libs = get['libs-only-l']
-    ldflags = (Shellwords.shellwords(ldflags) - Shellwords.shellwords(libs)).quote.join(" ")
-    $CFLAGS += " " << cflags
-    $LDFLAGS += " " << ldflags
-    $libs += " " << libs
-    Logging::message "package configuration for %s\n", pkg
-    Logging::message "cflags: %s\nldflags: %s\nlibs: %s\n\n",
-                     cflags, ldflags, libs
-    [cflags, ldflags, libs]
-  else
-    Logging::message "package configuration for %s is not found\n", pkg
-    nil
+        $LDFLAGS = [orig_ldflags, ldflags].join(' ')
+        Logging::message "package configuration for %s\n", pkg
+        Logging::message "incflags: %s\ncflags: %s\nldflags: %s\nlibs: %s\n\n",
+                         incflags, cflags, ldflags, libs
+        [[incflags, cflags].join(' '), ldflags, libs]
+      else
+        Logging::message "package configuration for %s is not found\n", pkg
+        nil
+      end
+    end
   end
-end
 
-def with_destdir(dir)
-  dir = dir.sub($dest_prefix_pattern, '')
-  /\A\$[\(\{]/ =~ dir ? dir : "$(DESTDIR)"+dir
-end
+  # :stopdoc:
 
-# Converts forward slashes to backslashes. Aimed at MS Windows.
-#
-# Internal use only.
-#
-def winsep(s)
-  s.tr('/', '\\')
-end
-
-# Converts native path to format acceptable in Makefile
-#
-# Internal use only.
-#
-if !CROSS_COMPILING
-  case CONFIG['build_os']
-  when 'mingw32'
-    def mkintpath(path)
-      # mingw uses make from msys and it needs special care
-      # converts from C:\some\path to /C/some/path
-      path = path.dup
-      path.tr!('\\', '/')
-      path.sub!(/\A([A-Za-z]):(?=\/)/, '/\1')
-      path
-    end
+  def with_destdir(dir)
+    dir = dir.sub($dest_prefix_pattern, '')
+    /\A\$[\(\{]/ =~ dir ? dir : "$(DESTDIR)"+dir
   end
-end
-unless defined?(mkintpath)
-  def mkintpath(path)
-    path
+
+  # Converts forward slashes to backslashes. Aimed at MS Windows.
+  #
+  # Internal use only.
+  #
+  def winsep(s)
+    s.tr('/', '\\')
   end
-end
 
-def configuration(srcdir)
-  mk = []
-  vpath = $VPATH.dup
+  # Converts native path to format acceptable in Makefile
+  #
+  # Internal use only.
+  #
   if !CROSS_COMPILING
     case CONFIG['build_os']
-    when 'cygwin'
+    when 'mingw32'
+      def mkintpath(path)
+        # mingw uses make from msys and it needs special care
+        # converts from C:\some\path to /C/some/path
+        path = path.dup
+        path.tr!('\\', '/')
+        path.sub!(/\A([A-Za-z]):(?=\/)/, '/\1')
+        path
+      end
+    when 'cygwin', 'msys'
       if CONFIG['target_os'] != 'cygwin'
-        vpath = vpath.map {|p| p.sub(/.*/, '$(shell cygpath -u \&)')}
+        def mkintpath(path)
+          IO.popen(["cygpath", "-u", path], &:read).chomp
+        end
       end
     end
   end
-  CONFIG["hdrdir"] ||= $hdrdir
-  mk << %{
+  unless method_defined?(:mkintpath)
+    def mkintpath(path)
+      path
+    end
+  end
+
+  def configuration(srcdir)
+    mk = []
+    verbose = with_config('verbose') ?  "1" : (CONFIG['MKMF_VERBOSE'] || "0")
+    vpath = $VPATH.dup
+    CONFIG["hdrdir"] ||= $hdrdir
+    mk << %{
 SHELL = /bin/sh
 
 # V=0 quiet, V=1 verbose.  other values don't work.
-V = 0
+V = #{verbose}
+V0 = $(V:0=)
 Q1 = $(V:1=)
 Q = $(Q1:0=@)
-n=$(NULLCMD)
-ECHO1 = $(V:1=@$n)
-ECHO = $(ECHO1:0=@echo)
+ECHO1 = $(V:1=@ #{CONFIG['NULLCMD']})
+ECHO = $(ECHO1:0=@ echo)
+NULLCMD = #{CONFIG['NULLCMD']}
 
 #### Start of system configuration section. ####
 #{"top_srcdir = " + $top_srcdir.sub(%r"\A#{Regexp.quote($topdir)}/", "$(topdir)/") if $extmk}
-srcdir = #{srcdir.gsub(/\$\((srcdir)\)|\$\{(srcdir)\}/) {mkintpath(CONFIG[$1||$2])}.quote}
-topdir = #{mkintpath($extmk ? CONFIG["topdir"] : $topdir).quote}
-hdrdir = #{mkintpath(CONFIG["hdrdir"]).quote}
-arch_hdrdir = #{$arch_hdrdir.quote}
+srcdir = #{srcdir.gsub(/\$\((srcdir)\)|\$\{(srcdir)\}/) {mkintpath(CONFIG[$1||$2]).unspace}}
+topdir = #{mkintpath(topdir = $extmk ? CONFIG["topdir"] : $topdir).unspace}
+hdrdir = #{(hdrdir = CONFIG["hdrdir"]) == topdir ? "$(topdir)" : mkintpath(hdrdir).unspace}
+arch_hdrdir = #{mkintpath($arch_hdrdir).unspace}
+PATH_SEPARATOR = #{CONFIG['PATH_SEPARATOR']}
 VPATH = #{vpath.join(CONFIG['PATH_SEPARATOR'])}
 }
-  if $extmk
-    mk << "RUBYLIB =\n""RUBYOPT = -\n"
-  end
-  if destdir = CONFIG["prefix"][$dest_prefix_pattern, 1]
-    mk << "\nDESTDIR = #{destdir}\n"
-  end
-  CONFIG.each do |key, var|
-    next unless /prefix$/ =~ key
-    mk << "#{key} = #{with_destdir(var)}\n"
-  end
-  CONFIG.each do |key, var|
-    next if /^abs_/ =~ key
-    next if /^(?:src|top|hdr)dir$/ =~ key
-    next unless /dir$/ =~ key
-    mk << "#{key} = #{with_destdir(var)}\n"
-  end
-  if !$extmk and !$configure_args.has_key?('--ruby') and
-      sep = config_string('BUILD_FILE_SEPARATOR')
-    sep = ":/=#{sep}"
-  else
-    sep = ""
-  end
-  possible_command = (proc {|s| s if /top_srcdir/ !~ s} unless $extmk)
-  extconf_h = $extconf_h ? "-DRUBY_EXTCONF_H=\\\"$(RUBY_EXTCONF_H)\\\" " : $defs.join(" ") << " "
-  mk << %{
-NULLCMD = #{CONFIG['NULLCMD']}
+    if $extmk
+      mk << "RUBYLIB =\n""RUBYOPT = -\n"
+    end
+    prefix = mkintpath(CONFIG["prefix"])
+    if destdir = prefix[$dest_prefix_pattern, 1]
+      mk << "\nDESTDIR = #{destdir}\n"
+      prefix = prefix[destdir.size..-1]
+    end
+    mk << "prefix = #{with_destdir(prefix).unspace}\n"
+    CONFIG.each do |key, var|
+      mk << "#{key} = #{with_destdir(mkintpath(var)).unspace}\n" if /.prefix$/ =~ key
+    end
+    CONFIG.each do |key, var|
+      next if /^abs_/ =~ key
+      next if /^(?:src|top(?:_src)?|build|hdr)dir$/ =~ key
+      next unless /dir$/ =~ key
+      mk << "#{key} = #{with_destdir(var)}\n"
+    end
+    if !$extmk and !$configure_args.has_key?('--ruby') and
+        sep = config_string('BUILD_FILE_SEPARATOR')
+      sep = ":/=#{sep}"
+    else
+      sep = ""
+    end
+    possible_command = (proc {|s| s if /top_srcdir|tooldir/ !~ s} unless $extmk)
+    extconf_h = $extconf_h ? "-DRUBY_EXTCONF_H=\\\"$(RUBY_EXTCONF_H)\\\" " : $defs.join(" ") << " "
+    headers = %w[
+      $(hdrdir)/ruby.h
+      $(hdrdir)/ruby/backward.h
+      $(hdrdir)/ruby/ruby.h
+      $(hdrdir)/ruby/defines.h
+      $(hdrdir)/ruby/missing.h
+      $(hdrdir)/ruby/intern.h
+      $(hdrdir)/ruby/st.h
+      $(hdrdir)/ruby/subst.h
+    ]
+    headers += $headers
+    if RULE_SUBST
+      headers.each {|h| h.sub!(/.*/, &RULE_SUBST.method(:%))}
+    end
+    headers << $config_h
+    headers << '$(RUBY_EXTCONF_H)' if $extconf_h
+    mk << %{
 
+CC_WRAPPER = #{CONFIG['CC_WRAPPER']}
 CC = #{CONFIG['CC']}
 CXX = #{CONFIG['CXX']}
 LIBRUBY = #{CONFIG['LIBRUBY']}
@@ -1703,36 +2155,51 @@ LIBRUBYARG_STATIC = #$LIBRUBYARG_STATIC
 empty =
 OUTFLAG = #{OUTFLAG}$(empty)
 COUTFLAG = #{COUTFLAG}$(empty)
+CSRCFLAG = #{CSRCFLAG}$(empty)
 
 RUBY_EXTCONF_H = #{$extconf_h}
 cflags   = #{CONFIG['cflags']}
+cxxflags = #{CONFIG['cxxflags']}
 optflags = #{CONFIG['optflags']}
 debugflags = #{CONFIG['debugflags']}
 warnflags = #{$warnflags}
-CFLAGS   = #{$static ? '' : CONFIG['CCDLFLAGS']} #$CFLAGS $(ARCH_FLAG)
+cppflags = #{CONFIG['cppflags']}
+CCDLFLAGS = #{$static ? '' : CONFIG['CCDLFLAGS']}
+CFLAGS   = $(CCDLFLAGS) #$CFLAGS $(ARCH_FLAG)
 INCFLAGS = -I. #$INCFLAGS
 DEFS     = #{CONFIG['DEFS']}
 CPPFLAGS = #{extconf_h}#{$CPPFLAGS}
-CXXFLAGS = $(CFLAGS) #{CONFIG['CXXFLAGS']}
+CXXFLAGS = $(CCDLFLAGS) #$CXXFLAGS $(ARCH_FLAG)
 ldflags  = #{$LDFLAGS}
 dldflags = #{$DLDFLAGS} #{CONFIG['EXTDLDFLAGS']}
 ARCH_FLAG = #{$ARCH_FLAG}
 DLDFLAGS = $(ldflags) $(dldflags) $(ARCH_FLAG)
 LDSHARED = #{CONFIG['LDSHARED']}
 LDSHAREDXX = #{config_string('LDSHAREDXX') || '$(LDSHARED)'}
+POSTLINK = #{config_string('POSTLINK', RbConfig::CONFIG)}
 AR = #{CONFIG['AR']}
+LD = #{CONFIG['LD']}
 EXEEXT = #{CONFIG['EXEEXT']}
 
-RUBY_BASE_NAME = #{CONFIG['RUBY_BASE_NAME']}
-RUBY_INSTALL_NAME = #{CONFIG['RUBY_INSTALL_NAME']}
-RUBY_SO_NAME = #{CONFIG['RUBY_SO_NAME']}
+}
+    CONFIG.each do |key, val|
+      mk << "#{key} = #{val}\n" if /^RUBY.*NAME/ =~ key
+    end
+    mk << %{
 arch = #{CONFIG['arch']}
 sitearch = #{CONFIG['sitearch']}
 ruby_version = #{RbConfig::CONFIG['ruby_version']}
-ruby = #{$ruby}
+ruby = #{$ruby.sub(%r[\A#{Regexp.quote(RbConfig::CONFIG['bindir'])}(?=/|\z)]) {'$(bindir)'}}
 RUBY = $(ruby#{sep})
+BUILTRUBY = #{if defined?($builtruby) && $builtruby
+    $builtruby
+  else
+    File.join('$(bindir)', CONFIG["RUBY_INSTALL_NAME"] + CONFIG['EXEEXT'])
+  end}
+ruby_headers = #{headers.join(' ')}
+
 RM = #{config_string('RM', &possible_command) || '$(RUBY) -run -e rm -- -f'}
-RM_RF = #{'$(RUBY) -run -e rm -- -rf'}
+RM_RF = #{config_string('RMALL', &possible_command) || '$(RUBY) -run -e rm -- -rf'}
 RMDIRS = #{config_string('RMDIRS', &possible_command) || '$(RUBY) -run -e rmdir -- -p'}
 MAKEDIRS = #{config_string('MAKEDIRS', &possible_command) || '@$(RUBY) -run -e mkdir -- -p'}
 INSTALL = #{config_string('INSTALL', &possible_command) || '@$(RUBY) -run -e install -- -vp'}
@@ -1745,227 +2212,269 @@ TOUCH = exit >
 
 preload = #{defined?($preload) && $preload ? $preload.join(' ') : ''}
 }
-  if $nmake == ?b
-    mk.each do |x|
-      x.gsub!(/^(MAKEDIRS|INSTALL_(?:PROG|DATA))+\s*=.*\n/) do
-        "!ifndef " + $1 + "\n" +
-        $& +
-        "!endif\n"
-      end
-    end
+    mk
   end
-  mk
-end
 
-def timestamp_file(name)
-  name = name.gsub(/(\$[({]|[})])|(\/+)|[^-.\w]+/) {$1 ? "" : $2 ? ".-." : "_"}
-  "./.#{name}.time"
-end
-# :startdoc:
-
-# creates a stub Makefile.
-#
-def dummy_makefile(srcdir)
-  configuration(srcdir) << <<RULES << CLEANINGS
+  def timestamp_file(name, target_prefix = nil)
+    pat = {}
+    name = '$(RUBYARCHDIR)' if name == '$(TARGET_SO_DIR)'
+    install_dirs.each do |n, d|
+      pat[n] = $` if /\$\(target_prefix\)\z/ =~ d
+    end
+    name = name.gsub(/\$\((#{pat.keys.join("|")})\)/) {pat[$1]+target_prefix}
+    name.sub!(/(\$\((?:site)?arch\))\/*/, '')
+    arch = $1 || ''
+    name.chomp!('/')
+    name = name.gsub(/(\$[({]|[})])|(\/+)|[^-.\w]+/) {$1 ? "" : $2 ? ".-." : "_"}
+    File.join("$(TIMESTAMP_DIR)", arch, "#{name.sub(/\A(?=.)/, '.')}.time")
+  end
+  # :startdoc:
+
+  # Creates a stub Makefile.
+  #
+  def dummy_makefile(srcdir)
+    configuration(srcdir) << <<RULES << CLEANINGS
 CLEANFILES = #{$cleanfiles.join(' ')}
 DISTCLEANFILES = #{$distcleanfiles.join(' ')}
 
 all install static install-so install-rb: Makefile
+	@$(NULLCMD)
 .PHONY: all install static install-so install-rb
-.PHONY: clean clean-so clean-rb
+.PHONY: clean clean-so clean-static clean-rb
 
 RULES
-end
+  end
 
-# Processes the data contents of the "depend" file.
-# Each line of this file is expected to be a file name.
-#
-# Returns the output of findings, in Makefile format.
-#
-def depend_rules(depend)
-  suffixes = []
-  depout = []
-  cont = implicit = nil
-  impconv = proc do
-    COMPILE_RULES.each {|rule| depout << (rule % implicit[0]) << implicit[1]}
-    implicit = nil
-  end
-  ruleconv = proc do |line|
-    if implicit
-      if /\A\t/ =~ line
-        implicit[1] << line
-        next
+  def each_compile_rules # :nodoc:
+    vpath_splat = /\$\(\*VPATH\*\)/
+    COMPILE_RULES.each do |rule|
+      if vpath_splat =~ rule
+        $VPATH.each do |path|
+          yield rule.sub(vpath_splat) {path}
+        end
       else
-        impconv[]
-      end
-    end
-    if m = /\A\.(\w+)\.(\w+)(?:\s*:)/.match(line)
-      suffixes << m[1] << m[2]
-      implicit = [[m[1], m[2]], [m.post_match]]
-      next
-    elsif RULE_SUBST and /\A(?!\s*\w+\s*=)[$\w][^#]*:/ =~ line
-      line.gsub!(%r"(\s)(?!\.)([^$(){}+=:\s\/\\,]+)(?=\s|\z)") {$1 + RULE_SUBST % $2}
-    end
-    depout << line
-  end
-  depend.each_line do |line|
-    line.gsub!(/\.o\b/, ".#{$OBJEXT}")
-    line.gsub!(/\$\((?:hdr|top)dir\)\/config.h/, $config_h)
-    line.gsub!(%r"\$\(hdrdir\)/(?!ruby(?![^:;/\s]))(?=[-\w]+\.h)", '\&ruby/')
-    if $nmake && /\A\s*\$\(RM|COPY\)/ =~ line
-      line.gsub!(%r"[-\w\./]{2,}"){$&.tr("/", "\\")}
-      line.gsub!(/(\$\((?!RM|COPY)[^:)]+)(?=\))/, '\1:/=\\')
-    end
-    if /(?:^|[^\\])(?:\\\\)*\\$/ =~ line
-      (cont ||= []) << line
-      next
-    elsif cont
-      line = (cont << line).join
-      cont = nil
-    end
-    ruleconv.call(line)
-  end
-  if cont
-    ruleconv.call(cont.join)
-  elsif implicit
-    impconv.call
-  end
-  unless suffixes.empty?
-    depout.unshift(".SUFFIXES: ." + suffixes.uniq.join(" .") + "\n\n")
-  end
-  depout.unshift("$(OBJS): $(RUBY_EXTCONF_H)\n\n") if $extconf_h
-  depout.flatten!
-  depout
-end
-
-# Generates the Makefile for your extension, passing along any options and
-# preprocessor constants that you may have generated through other methods.
-#
-# The +target+ name should correspond the name of the global function name
-# defined within your C extension, minus the 'Init_'.  For example, if your
-# C extension is defined as 'Init_foo', then your target would simply be 'foo'.
-#
-# If any '/' characters are present in the target name, only the last name
-# is interpreted as the target name, and the rest are considered toplevel
-# directory names, and the generated Makefile will be altered accordingly to
-# follow that directory structure.
-#
-# For example, if you pass 'test/foo' as a target name, your extension will
-# be installed under the 'test' directory.  This means that in order to
-# load the file within a Ruby program later, that directory structure will
-# have to be followed, e.g. "require 'test/foo'".
-#
-# The +srcprefix+ should be used when your source files are not in the same
-# directory as your build script. This will not only eliminate the need for
-# you to manually copy the source files into the same directory as your build
-# script, but it also sets the proper +target_prefix+ in the generated
-# Makefile.
-#
-# Setting the +target_prefix+ will, in turn, install the generated binary in
-# a directory under your RbConfig::CONFIG['sitearchdir'] that mimics your local
-# filesystem when you run 'make install'.
-#
-# For example, given the following file tree:
-#
-#    ext/
-#       extconf.rb
-#       test/
-#          foo.c
-#
-# And given the following code:
-#
-#    create_makefile('test/foo', 'test')
-#
-# That will set the +target_prefix+ in the generated Makefile to 'test'. That,
-# in turn, will create the following file tree when installed via the
-# 'make install' command:
-#
-#    /path/to/ruby/sitearchdir/test/foo.so
-#
-# It is recommended that you use this approach to generate your makefiles,
-# instead of copying files around manually, because some third party
-# libraries may depend on the +target_prefix+ being set properly.
-#
-# The +srcprefix+ argument can be used to override the default source
-# directory, i.e. the current directory . It is included as part of the VPATH
-# and added to the list of INCFLAGS.
-#
-def create_makefile(target, srcprefix = nil)
-  $target = target
-  libpath = $DEFLIBPATH|$LIBPATH
-  message "creating Makefile\n"
-  rm_f "conftest*"
-  if CONFIG["DLEXT"] == $OBJEXT
-    for lib in libs = $libs.split
-      lib.sub!(/-l(.*)/, %%"lib\\1.#{$LIBEXT}"%)
-    end
-    $defs.push(format("-DEXTLIB='%s'", libs.join(",")))
-  end
-
-  if target.include?('/')
-    target_prefix, target = File.split(target)
-    target_prefix[0,0] = '/'
-  else
-    target_prefix = ""
+        yield rule
+      end
+    end
   end
 
-  srcprefix ||= "$(srcdir)/#{srcprefix}".chomp('/')
-  RbConfig.expand(srcdir = srcprefix.dup)
+  # Processes the data contents of the "depend" file.  Each line of this file
+  # is expected to be a file name.
+  #
+  # Returns the output of findings, in Makefile format.
+  #
+  def depend_rules(depend)
+    suffixes = []
+    depout = []
+    cont = implicit = nil
+    impconv = proc do
+      each_compile_rules {|rule| depout << (rule % implicit[0]) << implicit[1]}
+      implicit = nil
+    end
+    ruleconv = proc do |line|
+      if implicit
+        if /\A\t/ =~ line
+          implicit[1] << line
+          next
+        else
+          impconv[]
+        end
+      end
+      if m = /\A\.(\w+)\.(\w+)(?:\s*:)/.match(line)
+        suffixes << m[1] << m[2]
+        implicit = [[m[1], m[2]], [m.post_match]]
+        next
+      elsif RULE_SUBST and /\A(?!\s*\w+\s*=)[$\w][^#]*:/ =~ line
+        line.sub!(/\s*\#.*$/, '')
+        comment = $&
+        line.gsub!(%r"(\s)(?!\.)([^$(){}+=:\s\\,]+)(?=\s|\z)") {$1 + RULE_SUBST % $2}
+        line = line.chomp + comment + "\n" if comment
+      end
+      depout << line
+    end
+    depend.each_line do |line|
+      line.gsub!(/\.o\b/, ".#{$OBJEXT}")
+      line.gsub!(/\{\$\(VPATH\)\}/, "") unless $nmake
+      line.gsub!(/\$\((?:hdr|top)dir\)\/config.h/, $config_h)
+      if $nmake && /\A\s*\$\(RM|COPY\)/ =~ line
+        line.gsub!(%r"[-\w\./]{2,}"){$&.tr("/", "\\")}
+        line.gsub!(/(\$\((?!RM|COPY)[^:)]+)(?=\))/, '\1:/=\\')
+      end
+      if /(?:^|[^\\])(?:\\\\)*\\$/ =~ line
+        (cont ||= []) << line
+        next
+      elsif cont
+        line = (cont << line).join
+        cont = nil
+      end
+      ruleconv.call(line)
+    end
+    if cont
+      ruleconv.call(cont.join)
+    elsif implicit
+      impconv.call
+    end
+    unless suffixes.empty?
+      depout.unshift(".SUFFIXES: ." + suffixes.uniq.join(" .") + "\n\n")
+    end
+    if $extconf_h
+      depout.unshift("$(OBJS): $(RUBY_EXTCONF_H)\n\n")
+      depout.unshift("$(OBJS): $(hdrdir)/ruby/win32.h\n\n") if $mswin or $mingw
+    end
+    depout.flatten!
+    depout
+  end
+
+  # Generates the Makefile for your extension, passing along any options and
+  # preprocessor constants that you may have generated through other methods.
+  #
+  # The +target+ name should correspond the name of the global function name
+  # defined within your C extension, minus the +Init_+.  For example, if your
+  # C extension is defined as +Init_foo+, then your target would simply be
+  # "foo".
+  #
+  # If any "/" characters are present in the target name, only the last name
+  # is interpreted as the target name, and the rest are considered toplevel
+  # directory names, and the generated Makefile will be altered accordingly to
+  # follow that directory structure.
+  #
+  # For example, if you pass "test/foo" as a target name, your extension will
+  # be installed under the "test" directory.  This means that in order to
+  # load the file within a Ruby program later, that directory structure will
+  # have to be followed, e.g. <code>require 'test/foo'</code>.
+  #
+  # The +srcprefix+ should be used when your source files are not in the same
+  # directory as your build script. This will not only eliminate the need for
+  # you to manually copy the source files into the same directory as your
+  # build script, but it also sets the proper +target_prefix+ in the generated
+  # Makefile.
+  #
+  # Setting the +target_prefix+ will, in turn, install the generated binary in
+  # a directory under your <code>RbConfig::CONFIG['sitearchdir']</code> that
+  # mimics your local filesystem when you run <code>make install</code>.
+  #
+  # For example, given the following file tree:
+  #
+  #   ext/
+  #     extconf.rb
+  #     test/
+  #       foo.c
+  #
+  # And given the following code:
+  #
+  #   create_makefile('test/foo', 'test')
+  #
+  # That will set the +target_prefix+ in the generated Makefile to "test".
+  # That, in turn, will create the following file tree when installed via the
+  # <code>make install</code> command:
+  #
+  #   /path/to/ruby/sitearchdir/test/foo.so
+  #
+  # It is recommended that you use this approach to generate your makefiles,
+  # instead of copying files around manually, because some third party
+  # libraries may depend on the +target_prefix+ being set properly.
+  #
+  # The +srcprefix+ argument can be used to override the default source
+  # directory, i.e. the current directory.  It is included as part of the
+  # +VPATH+ and added to the list of +INCFLAGS+.
+  #
+  # Yields the configuration part of the makefile to be generated, as an array
+  # of strings, if the block is given.  The returned value will be used the
+  # new configuration part.
+  #
+  #   create_makefile('foo') {|conf|
+  #     [
+  #       *conf,
+  #       "MACRO_YOU_NEED = something",
+  #     ]
+  #   }
+  #
+  # If "depend" file exist in the source directory, that content will be
+  # included in the generated makefile, with formatted by depend_rules method.
+  def create_makefile(target, srcprefix = nil)
+    $target = target
+    libpath = $DEFLIBPATH|$LIBPATH
+    message "creating Makefile\n"
+    MakeMakefile.rm_f "#{CONFTEST}*"
+    if CONFIG["DLEXT"] == $OBJEXT
+      for lib in libs = $libs.split(' ')
+        lib.sub!(/-l(.*)/, %%"lib\\1.#{$LIBEXT}"%)
+      end
+      $defs.push(format("-DEXTLIB='%s'", libs.join(",")))
+    end
 
-  ext = ".#{$OBJEXT}"
-  if not $objs
-    srcs = $srcs || Dir[File.join(srcdir, "*.{#{SRC_EXT.join(%q{,})}}")]
-    objs = srcs.inject(Hash.new {[]}) {|h, f| h[File.basename(f, ".*") << ext] <<= f; h}
-    $objs = objs.keys
-    unless objs.delete_if {|b, f| f.size == 1}.empty?
-      dups = objs.sort.map {|b, f|
-        "#{b[/.*\./]}{#{f.collect {|n| n[/([^.]+)\z/]}.join(',')}}"
+    if target.include?('/')
+      target_prefix, target = File.split(target)
+      target_prefix[0,0] = '/'
+    else
+      target_prefix = ""
+    end
+
+    srcprefix ||= "$(srcdir)/#{srcprefix}".chomp('/')
+    RbConfig.expand(srcdir = srcprefix.dup)
+
+    ext = ".#{$OBJEXT}"
+    orig_srcs = Dir[File.join(srcdir, "*.{#{SRC_EXT.join(%q{,})}}")]
+    if not $objs
+      srcs = $srcs || orig_srcs
+      $objs = []
+      objs = srcs.inject(Hash.new {[]}) {|h, f|
+        h.key?(o = File.basename(f, ".*") << ext) or $objs << o
+        h[o] <<= f
+        h
       }
-      abort "source files duplication - #{dups.join(", ")}"
+      unless objs.delete_if {|b, f| f.size == 1}.empty?
+        dups = objs.map {|b, f|
+          "#{b[/.*\./]}{#{f.collect {|n| n[/([^.]+)\z/]}.join(',')}}"
+        }
+        abort "source files duplication - #{dups.join(", ")}"
+      end
+    else
+      $objs.collect! {|o| File.basename(o, ".*") << ext} unless $OBJEXT == "o"
+      srcs = $srcs || $objs.collect {|o| o.chomp(ext) << ".c"}
     end
-  else
-    $objs.collect! {|o| File.basename(o, ".*") << ext} unless $OBJEXT == "o"
-    srcs = $srcs || $objs.collect {|o| o.chomp(ext) << ".c"}
-  end
-  $srcs = srcs
+    $srcs = srcs
 
-  target = nil if $objs.empty?
+    hdrs = Dir[File.join(srcdir, "*.{#{HDR_EXT.join(%q{,})}}")]
 
-  if target and EXPORT_PREFIX
-    if File.exist?(File.join(srcdir, target + '.def'))
-      deffile = "$(srcdir)/$(TARGET).def"
-      unless EXPORT_PREFIX.empty?
-        makedef = %{-pe "$_.sub!(/^(?=\\w)/,'#{EXPORT_PREFIX}') unless 1../^EXPORTS$/i"}
+    target = nil if $objs.empty?
+
+    if target and EXPORT_PREFIX
+      if File.exist?(File.join(srcdir, target + '.def'))
+        deffile = "$(srcdir)/$(TARGET).def"
+        unless EXPORT_PREFIX.empty?
+          makedef = %{$(RUBY) -pe "$$_.sub!(/^(?=\\w)/,'#{EXPORT_PREFIX}') unless 1../^EXPORTS$/i" #{deffile}}
+        end
+      else
+        makedef = %{(echo EXPORTS && echo $(TARGET_ENTRY))}
+      end
+      if makedef
+        $cleanfiles << '$(DEFFILE)'
+        origdef = deffile
+        deffile = "$(TARGET)-$(arch).def"
       end
-    else
-      makedef = %{-e "puts 'EXPORTS', '$(TARGET_ENTRY)'"}
     end
-    if makedef
-      $cleanfiles << '$(DEFFILE)'
-      origdef = deffile
-      deffile = "$(TARGET)-$(arch).def"
+    origdef ||= ''
+
+    if $extout and $INSTALLFILES
+      $cleanfiles.concat($INSTALLFILES.collect {|files, dir|File.join(dir, files.delete_prefix('./'))})
+      $distcleandirs.concat($INSTALLFILES.collect {|files, dir| dir})
     end
-  end
-  origdef ||= ''
 
-  if $extout and $INSTALLFILES
-    $cleanfiles.concat($INSTALLFILES.collect {|files, dir|File.join(dir, files.sub(/\A\.\//, ''))})
-    $distcleandirs.concat($INSTALLFILES.collect {|files, dir| dir})
-  end
+    if $extmk and $static
+      $defs << "-DRUBY_EXPORT=1"
+    end
 
-  if $extmk and not $extconf_h
-    create_header
-  end
+    if $extmk and not $extconf_h
+      create_header
+    end
 
-  libpath = libpathflag(libpath)
+    libpath = libpathflag(libpath)
 
-  dllib = target ? "$(TARGET).#{CONFIG['DLEXT']}" : ""
-  staticlib = target ? "$(TARGET).#$LIBEXT" : ""
-  mfile = open("Makefile", "wb")
-  conf = configuration(srcprefix)
-  conf = yield(conf) if block_given?
-  mfile.puts(conf)
-  mfile.print "
+    dllib = target ? "$(TARGET).#{CONFIG['DLEXT']}" : ""
+    staticlib = target ? "$(TARGET).#$LIBEXT" : ""
+    conf = configuration(srcprefix)
+    conf << "\
 libpath = #{($DEFLIBPATH|$LIBPATH).join(" ")}
 LIBPATH = #{libpath}
 DEFFILE = #{deffile}
@@ -1979,370 +2488,588 @@ extout_prefix = #{$extout_prefix}
 target_prefix = #{target_prefix}
 LOCAL_LIBS = #{$LOCAL_LIBS}
 LIBS = #{$LIBRUBYARG} #{$libs} #{$LIBS}
-SRCS = #{srcs.collect(&File.method(:basename)).join(' ')}
+ORIG_SRCS = #{orig_srcs.collect(&File.method(:basename)).join(' ')}
+SRCS = $(ORIG_SRCS) #{(srcs - orig_srcs).collect(&File.method(:basename)).join(' ')}
 OBJS = #{$objs.join(" ")}
+HDRS = #{hdrs.map{|h| '$(srcdir)/' + File.basename(h)}.join(' ')}
+LOCAL_HDRS = #{$headers.join(' ')}
 TARGET = #{target}
 TARGET_NAME = #{target && target[/\A\w+/]}
 TARGET_ENTRY = #{EXPORT_PREFIX || ''}Init_$(TARGET_NAME)
 DLLIB = #{dllib}
 EXTSTATIC = #{$static || ""}
 STATIC_LIB = #{staticlib unless $static.nil?}
-#{!$extout && defined?($installed_list) ? "INSTALLED_LIST = #{$installed_list}\n" : ""}
+#{!$extout && defined?($installed_list) ? %[INSTALLED_LIST = #{$installed_list}\n] : ""}
+TIMESTAMP_DIR = #{$extout && $extmk ? '$(extout)/.timestamp' : '.'}
+" #"
+    # TODO: fixme
+    install_dirs.each {|d| conf << ("%-14s= %s\n" % d) if /^[[:upper:]]/ =~ d[0]}
+    sodir = $extout ? '$(TARGET_SO_DIR)' : '$(RUBYARCHDIR)'
+    n = '$(TARGET_SO_DIR)$(TARGET)'
+    cleanobjs = ["$(OBJS)"]
+    cleanlibs = []
+    if $extmk
+      %w[bc i s].each {|ex| cleanobjs << "$(OBJS:.#{$OBJEXT}=.#{ex})"}
+    end
+    if target
+      config_string('cleanobjs') {|t| cleanobjs << t.gsub(/\$\*/, "$(TARGET)#{deffile ? '-$(arch)': ''}")}
+      cleanlibs << '$(TARGET_SO)'
+    end
+    config_string('cleanlibs') {|t| cleanlibs << t.gsub(/\$\*/) {n}}
+    conf << "\
+TARGET_SO_DIR =#{$extout ? " $(RUBYARCHDIR)/" : ''}
+TARGET_SO     = $(TARGET_SO_DIR)$(DLLIB)
+CLEANLIBS     = #{cleanlibs.join(' ')}
+CLEANOBJS     = #{cleanobjs.join(' ')} *.bak
+TARGET_SO_DIR_TIMESTAMP = #{timestamp_file(sodir, target_prefix)}
 " #"
-  # TODO: fixme
-  install_dirs.each {|d| mfile.print("%-14s= %s\n" % d) if /^[[:upper:]]/ =~ d[0]}
-  n = ($extout ? '$(RUBYARCHDIR)/' : '') + '$(TARGET)'
-  mfile.print "
-TARGET_SO     = #{($extout ? '$(RUBYARCHDIR)/' : '')}$(DLLIB)
-CLEANLIBS     = #{n}.#{CONFIG['DLEXT']} #{config_string('cleanlibs') {|t| t.gsub(/\$\*/) {n}}}
-CLEANOBJS     = *.#{$OBJEXT} #{config_string('cleanobjs') {|t| t.gsub(/\$\*/, "$(TARGET)#{deffile ? '-$(arch)': ''}")} if target} *.bak
 
+    conf = yield(conf) if block_given?
+    mfile = File.open("Makefile", "wb")
+    mfile.puts(conf)
+    mfile.print "
 all:    #{$extout ? "install" : target ? "$(DLLIB)" : "Makefile"}
-static: $(STATIC_LIB)#{$extout ? " install-rb" : ""}
+static: #{$extmk && !$static ? "all" : %[$(STATIC_LIB)#{$extout ? " install-rb" : ""}]}
 .PHONY: all install static install-so install-rb
-.PHONY: clean clean-so clean-rb
-"
-  mfile.print CLEANINGS
-  fsep = config_string('BUILD_FILE_SEPARATOR') {|s| s unless s == "/"}
-  if fsep
-    sep = ":/=#{fsep}"
-    fseprepl = proc {|s|
-      s = s.gsub("/", fsep)
-      s = s.gsub(/(\$\(\w+)(\))/) {$1+sep+$2}
-      s = s.gsub(/(\$\{\w+)(\})/) {$1+sep+$2}
-    }
-    rsep = ":#{fsep}=/"
-  else
-    fseprepl = proc {|s| s}
-    sep = ""
-    rsep = ""
-  end
-  dirs = []
-  mfile.print "install: install-so install-rb\n\n"
-  sodir = (dir = "$(RUBYARCHDIR)").dup
-  mfile.print("install-so: ")
-  if target
-    f = "$(DLLIB)"
-    dest = "#{dir}/#{f}"
-    mfile.puts dest
-    if $extout
-      mfile.print "clean-so::\n"
-      mfile.print "\t-$(Q)$(RM) #{fseprepl[dest]}\n"
-      mfile.print "\t-$(Q)$(RMDIRS) #{fseprepl[dir]}#{$ignore_error}\n"
+.PHONY: clean clean-so clean-static clean-rb
+" #"
+    mfile.print CLEANINGS
+    fsep = config_string('BUILD_FILE_SEPARATOR') {|s| s unless s == "/"}
+    if fsep
+      sep = ":/=#{fsep}"
+      fseprepl = proc {|s|
+        s = s.gsub("/", fsep)
+        s = s.gsub(/(\$\(\w+)(\))/) {$1+sep+$2}
+        s.gsub(/(\$\{\w+)(\})/) {$1+sep+$2}
+      }
+      rsep = ":#{fsep}=/"
     else
-      mfile.print "#{dest}: #{f}\n\t-$(Q)$(MAKEDIRS) $(@D#{sep})\n"
-      mfile.print "\t$(INSTALL_PROG) #{fseprepl[f]} $(@D#{sep})\n"
-      if defined?($installed_list)
-        mfile.print "\t@echo #{dir}/#{File.basename(f)}>>$(INSTALLED_LIST)\n"
+      fseprepl = proc {|s| s}
+      sep = ""
+      rsep = ""
+    end
+    dirs = []
+    mfile.print "install: install-so install-rb\n\n"
+    dir = sodir.dup
+    mfile.print("install-so: ")
+    if target
+      f = "$(DLLIB)"
+      dest = "$(TARGET_SO)"
+      stamp = '$(TARGET_SO_DIR_TIMESTAMP)'
+      if $extout
+        mfile.puts dest
+        mfile.print "clean-so::\n"
+        mfile.print "\t-$(Q)$(RM) #{fseprepl[dest]} #{fseprepl[stamp]}\n"
+        mfile.print "\t-$(Q)$(RM_RF) #{fseprepl['$(CLEANLIBS)']}\n"
+        mfile.print "\t-$(Q)$(RMDIRS) #{fseprepl[dir]}#{$ignore_error}\n"
+      else
+        mfile.print "#{f} #{stamp}\n"
+        mfile.print "\t$(INSTALL_PROG) #{fseprepl[f]} #{dir}\n"
+        if defined?($installed_list)
+          mfile.print "\t@echo #{dir}/#{File.basename(f)}>>$(INSTALLED_LIST)\n"
+        end
       end
+      mfile.print "clean-static::\n"
+      mfile.print "\t-$(Q)$(RM) $(STATIC_LIB)\n"
+    else
+      mfile.puts "Makefile"
     end
-    mfile.print "clean-static::\n"
-    mfile.print "\t-$(Q)$(RM) $(STATIC_LIB)\n"
-  else
-    mfile.puts "Makefile"
-  end
-  mfile.print("install-rb: pre-install-rb install-rb-default\n")
-  mfile.print("install-rb-default: pre-install-rb-default\n")
-  mfile.print("pre-install-rb: Makefile\n")
-  mfile.print("pre-install-rb-default: Makefile\n")
-  for sfx, i in [["-default", [["lib/**/*.rb", "$(RUBYLIBDIR)", "lib"]]], ["", $INSTALLFILES]]
-    files = install_files(mfile, i, nil, srcprefix) or next
-    for dir, *files in files
-      unless dirs.include?(dir)
-        dirs << dir
-        mfile.print "pre-install-rb#{sfx}: #{timestamp_file(dir)}\n"
-      end
-      for f in files
-        dest = "#{dir}/#{File.basename(f)}"
-        mfile.print("install-rb#{sfx}: #{dest} #{dir}\n")
-        mfile.print("#{dest}: #{f}\n")
-        mfile.print("\t$(Q) $(#{$extout ? 'COPY' : 'INSTALL_DATA'}) #{f} $(@D#{sep})\n")
-        if defined?($installed_list) and !$extout
-          mfile.print("\t@echo #{dest}>>$(INSTALLED_LIST)\n")
+    mfile.print("install-rb: pre-install-rb do-install-rb install-rb-default\n")
+    mfile.print("install-rb-default: pre-install-rb-default do-install-rb-default\n")
+    mfile.print("pre-install-rb: Makefile\n")
+    mfile.print("pre-install-rb-default: Makefile\n")
+    mfile.print("do-install-rb:\n")
+    mfile.print("do-install-rb-default:\n")
+    for sfx, i in [["-default", [["lib/**/*.rb", "$(RUBYLIBDIR)", "lib"]]], ["", $INSTALLFILES]]
+      files = install_files(mfile, i, nil, srcprefix) or next
+      for dir, *files in files
+        unless dirs.include?(dir)
+          dirs << dir
+          mfile.print "pre-install-rb#{sfx}: #{timestamp_file(dir, target_prefix)}\n"
         end
-        if $extout
-          mfile.print("clean-rb#{sfx}::\n")
-          mfile.print("\t@-$(RM) #{fseprepl[dest]}\n")
+        for f in files
+          dest = "#{dir}/#{File.basename(f)}"
+          mfile.print("do-install-rb#{sfx}: #{dest}\n")
+          mfile.print("#{dest}: #{f} #{timestamp_file(dir, target_prefix)}\n")
+          mfile.print("\t$(Q) $(#{$extout ? 'COPY' : 'INSTALL_DATA'}) #{f} $@\n")
+          if defined?($installed_list) and !$extout
+            mfile.print("\t@echo #{dest}>>$(INSTALLED_LIST)\n")
+          end
+          if $extout
+            mfile.print("clean-rb#{sfx}::\n")
+            mfile.print("\t-$(Q)$(RM) #{fseprepl[dest]}\n")
+          end
         end
       end
-    end
-    mfile.print "pre-install-rb#{sfx}:\n"
-    mfile.print("\t$(ECHO) installing#{sfx.sub(/^-/, " ")} #{target} libraries\n")
-    if $extout
-      dirs.uniq!
-      unless dirs.empty?
-        mfile.print("clean-rb#{sfx}::\n")
-        for dir in dirs.sort_by {|d| -d.count('/')}
-          mfile.print("\t@-$(RMDIRS) #{fseprepl[dir]}#{$ignore_error}\n")
+      mfile.print "pre-install-rb#{sfx}:\n"
+      if files.empty?
+        mfile.print("\t@$(NULLCMD)\n")
+      else
+        q = "$(MAKE) -q do-install-rb#{sfx}"
+        if $nmake
+          mfile.print "!if \"$(Q)\" == \"@\"\n\t@#{q} || \\\n!endif\n\t"
+        else
+          mfile.print "\t$(Q1:0=@#{q} || )"
+        end
+        mfile.print "$(ECHO1:0=echo) installing#{sfx.sub(/^-/, " ")} #{target} libraries\n"
+      end
+      if $extout
+        dirs.uniq!
+        unless dirs.empty?
+          mfile.print("clean-rb#{sfx}::\n")
+          for dir in dirs.sort_by {|d| -d.count('/')}
+            stamp = timestamp_file(dir, target_prefix)
+            mfile.print("\t-$(Q)$(RM) #{fseprepl[stamp]}\n")
+            mfile.print("\t-$(Q)$(RMDIRS) #{fseprepl[dir]}#{$ignore_error}\n")
+          end
         end
       end
     end
-  end
-  dirs.unshift(sodir) if target and !dirs.include?(sodir)
-  dirs.each do |d|
-    t = timestamp_file(d)
-    mfile.print "#{t}:\n\t$(Q) $(MAKEDIRS) #{d}\n\t$(Q) $(TOUCH) $@\n"
-  end
+    if target and !dirs.include?(sodir)
+      mfile.print "$(TARGET_SO_DIR_TIMESTAMP):\n\t$(Q) $(MAKEDIRS) $(@D) #{sodir}\n\t$(Q) $(TOUCH) $@\n"
+    end
+    dirs.each do |d|
+      t = timestamp_file(d, target_prefix)
+      mfile.print "#{t}:\n\t$(Q) $(MAKEDIRS) $(@D) #{d}\n\t$(Q) $(TOUCH) $@\n"
+    end
 
-  mfile.print <<-SITEINSTALL
+    mfile.print <<-SITEINSTALL
 
 site-install: site-install-so site-install-rb
 site-install-so: install-so
 site-install-rb: install-rb
 
-  SITEINSTALL
+    SITEINSTALL
 
-  return unless target
+    return unless target
 
-  mfile.puts SRC_EXT.collect {|e| ".path.#{e} = $(VPATH)"} if $nmake == ?b
-  mfile.print ".SUFFIXES: .#{SRC_EXT.join(' .')} .#{$OBJEXT}\n"
-  mfile.print "\n"
+    mfile.print ".SUFFIXES: .#{(SRC_EXT + [$OBJEXT, $ASMEXT]).compact.join(' .')}\n"
+    mfile.print "\n"
 
-  compile_command = "\n\t$(ECHO) compiling $(<#{rsep})\n\t$(Q) %s\n\n"
-  CXX_EXT.each do |e|
-    COMPILE_RULES.each do |rule|
-      mfile.printf(rule, e, $OBJEXT)
-      mfile.printf(compile_command, COMPILE_CXX)
+    compile_command = "\n\t$(ECHO) compiling $(<#{rsep})\n\t$(Q) %s\n\n"
+    command = compile_command % COMPILE_CXX
+    asm_command = compile_command.sub(/compiling/, 'translating') % ASSEMBLE_CXX
+    CXX_EXT.each do |e|
+      each_compile_rules do |rule|
+        mfile.printf(rule, e, $OBJEXT)
+        mfile.print(command)
+        mfile.printf(rule, e, $ASMEXT)
+        mfile.print(asm_command)
+      end
     end
-  end
-  C_EXT.each do |e|
-    COMPILE_RULES.each do |rule|
-      mfile.printf(rule, e, $OBJEXT)
-      mfile.printf(compile_command, COMPILE_C)
-    end
-  end
-
-  mfile.print "$(RUBYARCHDIR)/" if $extout
-  mfile.print "$(DLLIB): "
-  mfile.print "$(DEFFILE) " if makedef
-  mfile.print "$(OBJS) Makefile"
-  mfile.print " #{timestamp_file('$(RUBYARCHDIR)')}" if $extout
-  mfile.print "\n"
-  mfile.print "\t$(ECHO) linking shared-object #{target_prefix.sub(/\A\/(.*)/, '\1/')}$(DLLIB)\n"
-  mfile.print "\t-$(Q)$(RM) $(@#{sep})\n"
-  link_so = LINK_SO.gsub(/^/, "\t$(Q) ")
-  if srcs.any?(&%r"\.(?:#{CXX_EXT.join('|')})\z".method(:===))
-    link_so = link_so.sub(/\bLDSHARED\b/, '\&XX')
-  end
-  mfile.print link_so, "\n\n"
-  unless $static.nil?
-    mfile.print "$(STATIC_LIB): $(OBJS)\n\t@-$(RM) $(@#{sep})\n\t"
-    mfile.print "$(ECHO) linking static-library $(@#{rsep})\n\t$(Q) "
-    mfile.print "$(AR) #{config_string('ARFLAGS') || 'cru '}$@ $(OBJS)"
-    config_string('RANLIB') do |ranlib|
-      mfile.print "\n\t@-#{ranlib} $(DLLIB) 2> /dev/null || true"
-    end
-  end
-  mfile.print "\n\n"
-  if makedef
-    mfile.print "$(DEFFILE): #{origdef}\n"
-    mfile.print "\t$(ECHO) generating $(@#{rsep})\n"
-    mfile.print "\t$(Q) $(RUBY) #{makedef} #{origdef} > $@\n\n"
-  end
-
-  depend = File.join(srcdir, "depend")
-  if File.exist?(depend)
-    mfile.print("###\n", *depend_rules(File.read(depend)))
-  else
-    headers = %w[$(hdrdir)/ruby.h $(hdrdir)/ruby/defines.h]
-    if RULE_SUBST
-      headers.each {|h| h.sub!(/.*/, &RULE_SUBST.method(:%))}
+    command = compile_command % COMPILE_C
+    asm_command = compile_command.sub(/compiling/, 'translating') % ASSEMBLE_C
+    C_EXT.each do |e|
+      each_compile_rules do |rule|
+        mfile.printf(rule, e, $OBJEXT)
+        mfile.print(command)
+        mfile.printf(rule, e, $ASMEXT)
+        mfile.print(asm_command)
+      end
     end
-    headers << $config_h
-    headers << '$(RUBY_EXTCONF_H)' if $extconf_h
-    mfile.print "$(OBJS): ", headers.join(' '), "\n"
+
+    mfile.print "$(TARGET_SO): "
+    mfile.print "$(DEFFILE) " if makedef
+    mfile.print "$(OBJS) Makefile"
+    mfile.print " $(TARGET_SO_DIR_TIMESTAMP)" if $extout
+    mfile.print "\n"
+    mfile.print "\t$(ECHO) linking shared-object #{target_prefix.sub(/\A\/(.*)/, '\1/')}$(DLLIB)\n"
+    mfile.print "\t-$(Q)$(RM) $(@#{sep})\n"
+    link_so = LINK_SO.gsub(/^/, "\t$(Q) ")
+    if srcs.any?(&%r"\.(?:#{CXX_EXT.join('|')})\z".method(:===))
+      link_so = link_so.sub(/\bLDSHARED\b/, '\&XX')
+    end
+    mfile.print link_so, "\n\n"
+    unless $static.nil?
+      mfile.print "$(STATIC_LIB): $(OBJS)\n\t-$(Q)$(RM) $(@#{sep})\n\t"
+      mfile.print "$(ECHO) linking static-library $(@#{rsep})\n\t$(Q) "
+      mfile.print "$(AR) #{config_string('ARFLAGS') || 'cru '}$@ $(OBJS)"
+      config_string('RANLIB') do |ranlib|
+        mfile.print "\n\t-$(Q)#{ranlib} $(@)#{$ignore_error}"
+      end
+    end
+    mfile.print "\n\n"
+    if makedef
+      mfile.print "$(DEFFILE): #{origdef}\n"
+      mfile.print "\t$(ECHO) generating $(@#{rsep})\n"
+      mfile.print "\t$(Q) #{makedef} > $@\n\n"
+    end
+
+    depend = File.join(srcdir, "depend")
+    if File.exist?(depend)
+      mfile.print("###\n", *depend_rules(File.read(depend)))
+    else
+      mfile.print "$(OBJS): $(HDRS) $(ruby_headers)\n"
+    end
+
+    $makefile_created = true
+  ensure
+    mfile.close if mfile
   end
 
-  $makefile_created = true
-ensure
-  mfile.close if mfile
-end
+  # :stopdoc:
 
-# :stopdoc:
-
-def init_mkmf(config = CONFIG, rbconfig = RbConfig::CONFIG)
-  $makefile_created = false
-  $arg_config = []
-  $enable_shared = config['ENABLE_SHARED'] == 'yes'
-  $defs = []
-  $extconf_h = nil
-  if $warnflags = CONFIG['warnflags'] and CONFIG['GCC'] == 'yes'
-    # turn warnings into errors only for bundled extensions.
-    config['warnflags'] = $warnflags.gsub(/(\A|\s)-Werror[-=]/, '\1-W')
-    RbConfig.expand(rbconfig['warnflags'] = config['warnflags'].dup)
-    config.each do |key, val|
-      RbConfig.expand(rbconfig[key] = val.dup) if /warnflags/ =~ val
-    end
-    $warnflags = config['warnflags'] unless $extmk
-  end
-  $CFLAGS = with_config("cflags", arg_config("CFLAGS", config["CFLAGS"])).dup
-  $ARCH_FLAG = with_config("arch_flag", arg_config("ARCH_FLAG", config["ARCH_FLAG"])).dup
-  $CPPFLAGS = with_config("cppflags", arg_config("CPPFLAGS", config["CPPFLAGS"])).dup
-  $LDFLAGS = with_config("ldflags", arg_config("LDFLAGS", config["LDFLAGS"])).dup
-  $INCFLAGS = "-I$(arch_hdrdir)"
-  $INCFLAGS << " -I$(hdrdir)/ruby/backward" unless $extmk
-  $INCFLAGS << " -I$(hdrdir) -I$(srcdir)"
-  $DLDFLAGS = with_config("dldflags", arg_config("DLDFLAGS", config["DLDFLAGS"])).dup
-  $LIBEXT = config['LIBEXT'].dup
-  $OBJEXT = config["OBJEXT"].dup
-  $LIBS = "#{config['LIBS']} #{config['DLDLIBS']}"
-  $LIBRUBYARG = ""
-  $LIBRUBYARG_STATIC = config['LIBRUBYARG_STATIC']
-  $LIBRUBYARG_SHARED = config['LIBRUBYARG_SHARED']
-  $DEFLIBPATH = [$extmk ? "$(topdir)" : "$(libdir)"]
-  $DEFLIBPATH.unshift(".")
-  $LIBPATH = []
-  $INSTALLFILES = []
-  $NONINSTALLFILES = [/~\z/, /\A#.*#\z/, /\A\.#/, /\.bak\z/i, /\.orig\z/, /\.rej\z/, /\.l[ao]\z/, /\.o\z/]
-  $VPATH = %w[$(srcdir) $(arch_hdrdir)/ruby $(hdrdir)/ruby]
-
-  $objs = nil
-  $srcs = nil
-  $libs = ""
-  if $enable_shared or RbConfig.expand(config["LIBRUBY"].dup) != RbConfig.expand(config["LIBRUBY_A"].dup)
-    $LIBRUBYARG = config['LIBRUBYARG']
-  end
-
-  $LOCAL_LIBS = ""
-
-  $cleanfiles = config_string('CLEANFILES') {|s| Shellwords.shellwords(s)} || []
-  $cleanfiles << "mkmf.log"
-  $distcleanfiles = config_string('DISTCLEANFILES') {|s| Shellwords.shellwords(s)} || []
-  $distcleandirs = config_string('DISTCLEANDIRS') {|s| Shellwords.shellwords(s)} || []
-
-  $extout ||= nil
-  $extout_prefix ||= nil
-
-  @libdir_basename = config["libdir"] && config["libdir"][/\A\$\(exec_prefix\)\/(.*)/, 1] or "lib"
-
-  $arg_config.clear
-  dir_config("opt")
-end
+  def init_mkmf(config = CONFIG, rbconfig = RbConfig::CONFIG)
+    $makefile_created = false
+    $arg_config = []
+    $enable_shared = config['ENABLE_SHARED'] == 'yes'
+    $defs = []
+    $extconf_h = nil
+    $config_dirs = {}
+
+    if $warnflags = CONFIG['warnflags'] and CONFIG['GCC'] == 'yes'
+      # turn warnings into errors only for bundled extensions.
+      config['warnflags'] = $warnflags.gsub(/(?:\A|\s)-W\Kerror[-=](?!implicit-function-declaration)/, '')
+      if /icc\z/ =~ config['CC']
+        config['warnflags'].gsub!(/(\A|\s)-W(?:division-by-zero|deprecated-declarations)/, '\1')
+      end
+      RbConfig.expand(rbconfig['warnflags'] = config['warnflags'].dup)
+      config.each do |key, val|
+        RbConfig.expand(rbconfig[key] = val.dup) if /warnflags/ =~ val
+      end
+      $warnflags = config['warnflags'] unless $extmk
+    end
+    if (w = rbconfig['CC_WRAPPER']) and !w.empty? and !File.executable?(w)
+      rbconfig['CC_WRAPPER'] = config['CC_WRAPPER'] = ''
+    end
+    $CFLAGS = with_config("cflags", arg_config("CFLAGS", config["CFLAGS"])).dup
+    $CXXFLAGS = (with_config("cxxflags", arg_config("CXXFLAGS", config["CXXFLAGS"]))||'').dup
+    $ARCH_FLAG = with_config("arch_flag", arg_config("ARCH_FLAG", config["ARCH_FLAG"])).dup
+    $CPPFLAGS = with_config("cppflags", arg_config("CPPFLAGS", config["CPPFLAGS"])).dup
+    $LDFLAGS = with_config("ldflags", arg_config("LDFLAGS", config["LDFLAGS"])).dup
+    $INCFLAGS = "-I$(arch_hdrdir)"
+    $INCFLAGS << " -I$(hdrdir)/ruby/backward" unless $extmk
+    $INCFLAGS << " -I$(hdrdir) -I$(srcdir)"
+    $DLDFLAGS = with_config("dldflags", arg_config("DLDFLAGS", config["DLDFLAGS"])).dup
+    config_string("ADDITIONAL_DLDFLAGS") {|flags| $DLDFLAGS << " " << flags} unless $extmk
+    $LIBEXT = config['LIBEXT'].dup
+    $OBJEXT = config["OBJEXT"].dup
+    $EXEEXT = config["EXEEXT"].dup
+    $ASMEXT = config_string('ASMEXT', &:dup) || 'S'
+    $LIBS = "#{config['LIBS']} #{config['DLDLIBS']}"
+    $LIBRUBYARG = ""
+    $LIBRUBYARG_STATIC = config['LIBRUBYARG_STATIC']
+    $LIBRUBYARG_SHARED = config['LIBRUBYARG_SHARED']
+    $DEFLIBPATH = [$extmk ? "$(topdir)" : "$(#{config["libdirname"] || "libdir"})"]
+    $DEFLIBPATH.unshift(".")
+    $LIBPATH = []
+    $INSTALLFILES = []
+    $NONINSTALLFILES = [/~\z/, /\A#.*#\z/, /\A\.#/, /\.bak\z/i, /\.orig\z/, /\.rej\z/, /\.l[ao]\z/, /\.o\z/]
+    $VPATH = %w[$(srcdir) $(arch_hdrdir)/ruby $(hdrdir)/ruby]
+
+    $objs = nil
+    $srcs = nil
+    $headers = []
+    $libs = ""
+    if $enable_shared or RbConfig.expand(config["LIBRUBY"].dup) != RbConfig.expand(config["LIBRUBY_A"].dup)
+      $LIBRUBYARG = config['LIBRUBYARG']
+    end
 
-FailedMessage = <<MESSAGE
-Could not create Makefile due to some reason, probably lack of
-necessary libraries and/or headers.  Check the mkmf.log file for more
-details.  You may need configuration options.
+    $LOCAL_LIBS = ""
+
+    $cleanfiles = config_string('CLEANFILES') {|s| Shellwords.shellwords(s)} || []
+    $cleanfiles << "mkmf.log"
+    $distcleanfiles = config_string('DISTCLEANFILES') {|s| Shellwords.shellwords(s)} || []
+    $distcleandirs = config_string('DISTCLEANDIRS') {|s| Shellwords.shellwords(s)} || []
+
+    $extout ||= nil
+    $extout_prefix ||= nil
+
+    $arg_config.clear
+    $config_dirs.clear
+    dir_config("opt")
+  end
+
+  FailedMessage = <<MESSAGE
+Could not create Makefile due to some reason, probably lack of necessary
+libraries and/or headers.  Check the mkmf.log file for more details.  You may
+need configuration options.
 
 Provided configuration options:
 MESSAGE
 
-# Returns whether or not the Makefile was successfully generated. If not,
-# the script will abort with an error message.
-#
-# Internal use only.
-#
-def mkmf_failed(path)
-  unless $makefile_created or File.exist?("Makefile")
-    opts = $arg_config.collect {|t, n| "\t#{t}#{n ? "=#{n}" : ""}\n"}
-    abort "*** #{path} failed ***\n" + FailedMessage + opts.join
+  # Returns whether or not the Makefile was successfully generated. If not,
+  # the script will abort with an error message.
+  #
+  # Internal use only.
+  #
+  def mkmf_failed(path)
+    unless $makefile_created or File.exist?("Makefile")
+      opts = $arg_config.collect {|t, n| "\t#{t}#{n ? "=#{n}" : ""}\n"}
+      abort "*** #{path} failed ***\n" + FailedMessage + opts.join
+    end
   end
-end
 
-def MAIN_DOES_NOTHING(*refs)
-  src = MAIN_DOES_NOTHING
-  unless refs.empty?
-    src = src.sub(/\{/) do
-      $& +
-        "\n  if (argc > 1000000) {\n" +
-        refs.map {|n|"    printf(\"%p\", &#{n});\n"}.join("") +
-        "  }\n"
+  private
+
+  def _libdir_basename
+    @libdir_basename ||= config_string("libdir") {|name| name[/\A\$\(exec_prefix\)\/(.*)/, 1]} || "lib"
+  end
+
+  def MAIN_DOES_NOTHING(*refs)
+    src = MAIN_DOES_NOTHING
+    unless refs.empty?
+      src = src.sub(/\{/) do
+        $& +
+          "\n  if (argc > 1000000) {\n" +
+          refs.map {|n|"    int (* volatile #{n}p)(void)=(int (*)(void))&#{n};\n"}.join("") +
+          refs.map {|n|"    printf(\"%d\", (*#{n}p)());\n"}.join("") +
+          "  }\n"
+      end
     end
+    src
   end
-  src
-end
 
-# :startdoc:
+  extend self
+  init_mkmf
 
-init_mkmf
+  $make = with_config("make-prog", ENV["MAKE"] || "make")
+  make, = Shellwords.shellwords($make)
+  $nmake = nil
+  case
+  when $mswin
+    $nmake = ?m if /nmake/i =~ make
+  end
+  $ignore_error = " 2> #{File::NULL} || #{$mswin ? 'exit /b0' : 'true'}"
 
-$make = with_config("make-prog", ENV["MAKE"] || "make")
-make, = Shellwords.shellwords($make)
-$nmake = nil
-case
-when $mswin
-  $nmake = ?m if /nmake/i =~ make
-when $bccwin
-  $nmake = ?b if /Borland/i =~ `#{make} -h`
-end
-$ignore_error = $nmake ? '' : ' 2> /dev/null || true'
-
-RbConfig::CONFIG["srcdir"] = CONFIG["srcdir"] =
-  $srcdir = arg_config("--srcdir", File.dirname($0))
-$configure_args["--topsrcdir"] ||= $srcdir
-if $curdir = arg_config("--curdir")
-  RbConfig.expand(curdir = $curdir.dup)
-else
-  curdir = $curdir = "."
-end
-unless File.expand_path(RbConfig::CONFIG["topdir"]) == File.expand_path(curdir)
-  CONFIG["topdir"] = $curdir
-  RbConfig::CONFIG["topdir"] = curdir
-end
-$configure_args["--topdir"] ||= $curdir
-$ruby = arg_config("--ruby", File.join(RbConfig::CONFIG["bindir"], CONFIG["ruby_install_name"]))
+  RbConfig::CONFIG["srcdir"] = CONFIG["srcdir"] =
+    $srcdir = arg_config("--srcdir", File.dirname($0))
+  $configure_args["--topsrcdir"] ||= $srcdir
+  if $curdir = arg_config("--curdir")
+    RbConfig.expand(curdir = $curdir.dup)
+  else
+    curdir = $curdir = "."
+  end
+  unless File.expand_path(RbConfig::CONFIG["topdir"]) == File.expand_path(curdir)
+    CONFIG["topdir"] = $curdir
+    RbConfig::CONFIG["topdir"] = curdir
+  end
+  $configure_args["--topdir"] ||= $curdir
+  $ruby = arg_config("--ruby", File.join(RbConfig::CONFIG["bindir"], CONFIG["ruby_install_name"]))
+
+  RbConfig.expand(CONFIG["RUBY_SO_NAME"])
+
+  # :startdoc:
 
-split = Shellwords.method(:shellwords).to_proc
+  split = Shellwords.method(:shellwords).to_proc
 
-EXPORT_PREFIX = config_string('EXPORT_PREFIX') {|s| s.strip}
+  ##
+  # The prefix added to exported symbols automatically
 
-hdr = ['#include "ruby.h"' "\n"]
-config_string('COMMON_MACROS') do |s|
-  Shellwords.shellwords(s).each do |w|
-    w, v = w.split(/=/, 2)
-    hdr << "#ifndef #{w}"
-    hdr << "#define #{[w, v].compact.join(" ")}"
-    hdr << "#endif /* #{w} */"
+  EXPORT_PREFIX = config_string('EXPORT_PREFIX') {|s| s.strip}
+
+  hdr = ['#include "ruby.h"' "\n"]
+  config_string('COMMON_MACROS') do |s|
+    Shellwords.shellwords(s).each do |w|
+      w, v = w.split(/=/, 2)
+      hdr << "#ifndef #{w}"
+      hdr << "#define #{[w, v].compact.join(" ")}"
+      hdr << "#endif /* #{w} */"
+    end
   end
-end
-config_string('COMMON_HEADERS') do |s|
-  Shellwords.shellwords(s).each {|w| hdr << "#include <#{w}>"}
-end
-COMMON_HEADERS = hdr.join("\n")
-COMMON_LIBS = config_string('COMMON_LIBS', &split) || []
-
-COMPILE_RULES = config_string('COMPILE_RULES', &split) || %w[.%s.%s:]
-RULE_SUBST = config_string('RULE_SUBST')
-COMPILE_C = config_string('COMPILE_C') || '$(CC) $(INCFLAGS) $(CPPFLAGS) $(CFLAGS) $(COUTFLAG)$@ -c $<'
-COMPILE_CXX = config_string('COMPILE_CXX') || '$(CXX) $(INCFLAGS) $(CPPFLAGS) $(CXXFLAGS) $(COUTFLAG)$@ -c $<'
-TRY_LINK = config_string('TRY_LINK') ||
-  "$(CC) #{OUTFLAG}conftest $(INCFLAGS) $(CPPFLAGS) " \
-  "$(CFLAGS) $(src) $(LIBPATH) $(LDFLAGS) $(ARCH_FLAG) $(LOCAL_LIBS) $(LIBS)"
-LINK_SO = (config_string('LINK_SO') || "").sub(/^$/) do
-  if CONFIG["DLEXT"] == $OBJEXT
-    "ld $(DLDFLAGS) -r -o $@ $(OBJS)\n"
-  else
-    "$(LDSHARED) #{OUTFLAG}$@ $(OBJS) " \
-    "$(LIBPATH) $(DLDFLAGS) $(LOCAL_LIBS) $(LIBS)"
+  config_string('COMMON_HEADERS') do |s|
+    Shellwords.shellwords(s).each {|w| hdr << "#include <#{w}>"}
   end
-end
-LIBPATHFLAG = config_string('LIBPATHFLAG') || ' -L"%s"'
-RPATHFLAG = config_string('RPATHFLAG') || ''
-LIBARG = config_string('LIBARG') || '-l%s'
-MAIN_DOES_NOTHING = config_string('MAIN_DOES_NOTHING') || "int main(int argc, char **argv)\n{\n  return 0;\n}"
-UNIVERSAL_INTS = config_string('UNIVERSAL_INTS') {|s| Shellwords.shellwords(s)} ||
-  %w[int short long long\ long]
-
-sep = config_string('BUILD_FILE_SEPARATOR') {|s| ":/=#{s}" if s != "/"} || ""
-CLEANINGS = "
+
+  ##
+  # Common headers for Ruby C extensions
+
+  COMMON_HEADERS = hdr.join("\n")
+
+  ##
+  # Common libraries for Ruby C extensions
+
+  COMMON_LIBS = config_string('COMMON_LIBS', &split) || []
+
+  ##
+  # make compile rules
+
+  COMPILE_RULES = config_string('COMPILE_RULES', &split) || %w[.%s.%s:]
+
+  ##
+  # Substitution in rules for NMake
+
+  RULE_SUBST = config_string('RULE_SUBST')
+
+  ##
+  # Command which will compile C files in the generated Makefile
+
+  COMPILE_C = config_string('COMPILE_C') || '$(CC) $(INCFLAGS) $(CPPFLAGS) $(CFLAGS) $(COUTFLAG)$@ -c $(CSRCFLAG)$<'
+
+  ##
+  # Command which will compile C++ files in the generated Makefile
+
+  COMPILE_CXX = config_string('COMPILE_CXX') || '$(CXX) $(INCFLAGS) $(CPPFLAGS) $(CXXFLAGS) $(COUTFLAG)$@ -c $(CSRCFLAG)$<'
+
+  ##
+  # Command which will translate C files to assembler sources in the generated Makefile
+
+  ASSEMBLE_C = config_string('ASSEMBLE_C') || COMPILE_C.sub(/(?<=\s)-c(?=\s)/, '-S')
+
+  ##
+  # Command which will translate C++ files to assembler sources in the generated Makefile
+
+  ASSEMBLE_CXX = config_string('ASSEMBLE_CXX') || COMPILE_CXX.sub(/(?<=\s)-c(?=\s)/, '-S')
+
+  ##
+  # Command which will compile a program in order to test linking a library
+
+  TRY_LINK = config_string('TRY_LINK') ||
+    "$(CC) #{OUTFLAG}#{CONFTEST}#{$EXEEXT} $(INCFLAGS) $(CPPFLAGS) " \
+    "$(CFLAGS) $(src) $(LIBPATH) $(LDFLAGS) $(ARCH_FLAG) $(LOCAL_LIBS) $(LIBS)"
+
+  ##
+  # Command which will link a shared library
+
+  LINK_SO = (config_string('LINK_SO') || "").sub(/^$/) do
+    if CONFIG["DLEXT"] == $OBJEXT
+      "ld $(DLDFLAGS) -r -o $@ $(OBJS)\n"
+    else
+      "$(LDSHARED) #{OUTFLAG}$@ $(OBJS) " \
+      "$(LIBPATH) $(DLDFLAGS) $(LOCAL_LIBS) $(LIBS)"
+    end
+  end
+
+  ##
+  # Argument which will add a library path to the linker
+
+  LIBPATHFLAG = config_string('LIBPATHFLAG') || '-L%s'
+
+  ##
+  # Argument which will add a runtime library path to the linker
+
+  RPATHFLAG = config_string('RPATHFLAG') || ''
+
+  ##
+  # Argument which will add a library to the linker
+
+  LIBARG = config_string('LIBARG') || '-l%s'
+
+  ##
+  # A C main function which does no work
+
+  MAIN_DOES_NOTHING = config_string('MAIN_DOES_NOTHING') || "int main(int argc, char **argv)\n{\n  return !!argv[argc];\n}"
+
+  ##
+  # The type names for convertible_int
+
+  UNIVERSAL_INTS = config_string('UNIVERSAL_INTS') {|s| Shellwords.shellwords(s)} ||
+    %w[int short long long\ long]
+
+  sep = config_string('BUILD_FILE_SEPARATOR') {|s| ":/=#{s}" if s != "/"} || ""
+
+  ##
+  # Makefile rules that will clean the extension build directory
+
+  CLEANINGS = "
 clean-static::
 clean-rb-default::
 clean-rb::
 clean-so::
 clean: clean-so clean-static clean-rb-default clean-rb
-\t\t-$(Q)$(RM) $(CLEANLIBS#{sep}) $(CLEANOBJS#{sep}) $(CLEANFILES#{sep}) .*.time
+\t\t-$(Q)$(RM_RF) $(CLEANLIBS#{sep}) $(CLEANOBJS#{sep}) $(CLEANFILES#{sep}) .*.time
 
 distclean-rb-default::
 distclean-rb::
 distclean-so::
-distclean: clean distclean-so distclean-rb-default distclean-rb
-\t\t@-$(RM) Makefile $(RUBY_EXTCONF_H) conftest.* mkmf.log
-\t\t@-$(RM) core ruby$(EXEEXT) *~ $(DISTCLEANFILES#{sep})
-\t\t@-$(RMDIRS) $(DISTCLEANDIRS#{sep})#{$ignore_error}
+distclean-static::
+distclean: clean distclean-so distclean-static distclean-rb-default distclean-rb
+\t\t-$(Q)$(RM) Makefile $(RUBY_EXTCONF_H) #{CONFTEST}.* mkmf.log#{' exts.mk' if $extmk}
+\t\t-$(Q)$(RM) core ruby$(EXEEXT) *~ $(DISTCLEANFILES#{sep})
+\t\t-$(Q)$(RMDIRS) $(DISTCLEANDIRS#{sep})#{$ignore_error}
 
 realclean: distclean
 "
 
+  @lang = Hash.new(self)
+
+  ##
+  # Retrieves the module for _name_ language.
+  def self.[](name)
+    @lang.fetch(name)
+  end
+
+  ##
+  # Defines the module for _name_ language.
+  def self.[]=(name, mod)
+    @lang[name] = mod
+  end
+
+  ##
+  # The language that this module is for
+  LANGUAGE = -"C"
+
+  self[self::LANGUAGE] = self
+
+  cxx = Module.new do
+    # Module for C++
+
+    include MakeMakefile
+    extend self
+
+    # :stopdoc:
+
+    CONFTEST_CXX = "#{CONFTEST}.#{config_string('CXX_EXT') || CXX_EXT[0]}"
+
+    TRY_LINK_CXX = config_string('TRY_LINK_CXX') ||
+                   ((cmd = TRY_LINK.gsub(/\$\(C(?:C|(FLAGS))\)/, '$(CXX\1)')) != TRY_LINK && cmd) ||
+                   "$(CXX) #{OUTFLAG}#{CONFTEST}#{$EXEEXT} $(INCFLAGS) $(CPPFLAGS) " \
+                   "$(CXXFLAGS) $(src) $(LIBPATH) $(LDFLAGS) $(ARCH_FLAG) $(LOCAL_LIBS) $(LIBS)"
+
+    def have_devel?
+      unless defined? @have_devel
+        @have_devel = true
+        @have_devel = try_link(MAIN_DOES_NOTHING)
+      end
+      @have_devel
+    end
+
+    def conftest_source
+      CONFTEST_CXX
+    end
+
+    def cc_command(opt="")
+      conf = cc_config(opt)
+      cxx_command(opt, conf)
+      RbConfig::expand("$(CXX) #$INCFLAGS #$CPPFLAGS #$CXXFLAGS #$ARCH_FLAG #{opt} -c #{CONFTEST_CXX}",
+                       conf)
+    end
+
+    def cpp_command(outfile, opt="")
+      conf = cpp_config(opt)
+      cxx = cxx_command(opt, conf)
+      cpp = conf['CPP'].sub(/(\A|\s)#{Regexp.quote(conf['CC'])}(?=\z|\s)/) {
+        "#$1#{cxx}"
+      }
+      RbConfig::expand("#{cpp} #$INCFLAGS #$CPPFLAGS #$CXXFLAGS #{opt} #{CONFTEST_CXX} #{outfile}",
+                       conf)
+    end
+
+    def link_command(ldflags, *opts)
+      conf = link_config(ldflags, *opts)
+      RbConfig::expand(TRY_LINK_CXX.dup, conf)
+    end
+
+    def cxx_command(opt="", conf = cc_config(opt))
+      cxx = conf['CXX']
+      raise Errno::ENOENT, "C++ compiler not found" if !cxx or cxx == 'false'
+      cxx
+    end
+
+    # :startdoc:
+  end
+
+  cxx::LANGUAGE = -"C++"
+  self[cxx::LANGUAGE] = cxx
+end
+
+# MakeMakefile::Global = #
+m = Module.new {
+  include(MakeMakefile)
+  private(*MakeMakefile.public_instance_methods(false))
+}
+include m
+
 if not $extmk and /\A(extconf|makefile).rb\z/ =~ File.basename($0)
   END {mkmf_failed($0)}
 end
diff --git a/lib/monitor.rb b/lib/monitor.rb
index 9e26ec1de1..21329a5de7 100644
--- a/lib/monitor.rb
+++ b/lib/monitor.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # = monitor.rb
 #
 # Copyright (C) 2001  Shugo Maeda <shugo@ruby-lang.org>
@@ -5,20 +6,17 @@
 # This library is distributed under the terms of the Ruby license.
 # You can freely distribute/modify this library.
 #
-
-require 'thread'
-
 #
 # In concurrent programming, a monitor is an object or module intended to be
-# used safely by more than one thread.  The defining characteristic of a
-# monitor is that its methods are executed with mutual exclusion.  That is, at
+# used safely by more than one thread. The defining characteristic of a
+# monitor is that its methods are executed with mutual exclusion. That is, at
 # each point in time, at most one thread may be executing any of its methods.
 # This mutual exclusion greatly simplifies reasoning about the implementation
 # of monitors compared to reasoning about parallel code that updates a data
 # structure.
 #
 # You can read more about the general principles on the Wikipedia page for
-# Monitors[http://en.wikipedia.org/wiki/Monitor_%28synchronization%29]
+# Monitors[https://en.wikipedia.org/wiki/Monitor_%28synchronization%29].
 #
 # == Examples
 #
@@ -49,7 +47,7 @@ require 'thread'
 #   end
 #
 # The consumer thread waits for the producer thread to push a line to buf
-# while <tt>buf.empty?</tt>.  The producer thread (main thread) reads a
+# while <tt>buf.empty?</tt>. The producer thread (main thread) reads a
 # line from ARGF and pushes it into buf then calls <tt>empty_cond.signal</tt>
 # to notify the consumer thread of new data.
 #
@@ -88,75 +86,16 @@ require 'thread'
 # MonitorMixin module.
 #
 module MonitorMixin
+  ConditionVariable = Monitor::ConditionVariable # :nodoc:
+
   #
   # FIXME: This isn't documented in Nutshell.
   #
   # Since MonitorMixin.new_cond returns a ConditionVariable, and the example
   # above calls while_wait and signal, this class should be documented.
   #
-  class ConditionVariable
-    class Timeout < Exception; end
-
-    #
-    # Releases the lock held in the associated monitor and waits; reacquires the lock on wakeup.
-    #
-    # If +timeout+ is given, this method returns after +timeout+ seconds passed,
-    # even if no other thread doesn't signal.
-    #
-    def wait(timeout = nil)
-      @monitor.__send__(:mon_check_owner)
-      count = @monitor.__send__(:mon_exit_for_cond)
-      begin
-        @cond.wait(@monitor.instance_variable_get("@mon_mutex"), timeout)
-        return true
-      ensure
-        @monitor.__send__(:mon_enter_for_cond, count)
-      end
-    end
-
-    #
-    # Calls wait repeatedly while the given block yields a truthy value.
-    #
-    def wait_while
-      while yield
-        wait
-      end
-    end
-
-    #
-    # Calls wait repeatedly until the given block yields a truthy value.
-    #
-    def wait_until
-      until yield
-        wait
-      end
-    end
 
-    #
-    # Wakes up the first thread in line waiting for this lock.
-    #
-    def signal
-      @monitor.__send__(:mon_check_owner)
-      @cond.signal
-    end
-
-    #
-    # Wakes up all threads waiting for this lock.
-    #
-    def broadcast
-      @monitor.__send__(:mon_check_owner)
-      @cond.broadcast
-    end
-
-    private
-
-    def initialize(monitor)
-      @monitor = monitor
-      @cond = ::ConditionVariable.new
-    end
-  end
-
-  def self.extend_object(obj)
+  def self.extend_object(obj) # :nodoc:
     super(obj)
     obj.__send__(:mon_initialize)
   end
@@ -165,14 +104,7 @@ module MonitorMixin
   # Attempts to enter exclusive section.  Returns +false+ if lock fails.
   #
   def mon_try_enter
-    if @mon_owner != Thread.current
-      unless @mon_mutex.try_lock
-        return false
-      end
-      @mon_owner = Thread.current
-    end
-    @mon_count += 1
-    return true
+    @mon_data.try_enter
   end
   # For backward compatibility
   alias try_mon_enter mon_try_enter
@@ -181,11 +113,7 @@ module MonitorMixin
   # Enters exclusive section.
   #
   def mon_enter
-    if @mon_owner != Thread.current
-      @mon_mutex.lock
-      @mon_owner = Thread.current
-    end
-    @mon_count += 1
+    @mon_data.enter
   end
 
   #
@@ -193,11 +121,21 @@ module MonitorMixin
   #
   def mon_exit
     mon_check_owner
-    @mon_count -=1
-    if @mon_count == 0
-      @mon_owner = nil
-      @mon_mutex.unlock
-    end
+    @mon_data.exit
+  end
+
+  #
+  # Returns true if this monitor is locked by any thread
+  #
+  def mon_locked?
+    @mon_data.mon_locked?
+  end
+
+  #
+  # Returns true if this monitor is locked by current thread.
+  #
+  def mon_owned?
+    @mon_data.mon_owned?
   end
 
   #
@@ -205,22 +143,21 @@ module MonitorMixin
   # section automatically when the block exits.  See example under
   # +MonitorMixin+.
   #
-  def mon_synchronize
-    mon_enter
-    begin
-      yield
-    ensure
-      mon_exit
-    end
+  def mon_synchronize(&b)
+    @mon_data.synchronize(&b)
   end
   alias synchronize mon_synchronize
 
   #
   # Creates a new MonitorMixin::ConditionVariable associated with the
-  # receiver.
+  # Monitor object.
   #
   def new_cond
-    return ConditionVariable.new(self)
+    unless defined?(@mon_data)
+      mon_initialize
+      @mon_initialized_by_new_cond = true
+    end
+    return ConditionVariable.new(@mon_data)
   end
 
   private
@@ -228,7 +165,7 @@ module MonitorMixin
   # Use <tt>extend MonitorMixin</tt> or <tt>include MonitorMixin</tt> instead
   # of this constructor.  Have look at the examples above to understand how to
   # use this module.
-  def initialize(*args)
+  def initialize(...)
     super
     mon_initialize
   end
@@ -236,48 +173,32 @@ module MonitorMixin
   # Initializes the MonitorMixin after being included in a class or when an
   # object has been extended with the MonitorMixin
   def mon_initialize
-    @mon_owner = nil
-    @mon_count = 0
-    @mon_mutex = Mutex.new
-  end
-
-  def mon_check_owner
-    if @mon_owner != Thread.current
-      raise ThreadError, "current thread not owner"
+    if defined?(@mon_data)
+      if defined?(@mon_initialized_by_new_cond)
+        return # already initialized.
+      elsif @mon_data_owner_object_id == self.object_id
+        raise ThreadError, "already initialized"
+      end
     end
+    @mon_data = ::Monitor.new
+    @mon_data_owner_object_id = self.object_id
   end
 
-  def mon_enter_for_cond(count)
-    @mon_owner = Thread.current
-    @mon_count = count
-  end
-
-  def mon_exit_for_cond
-    count = @mon_count
-    @mon_owner = nil
-    @mon_count = 0
-    return count
+  # Ensures that the MonitorMixin is owned by the current thread,
+  # otherwise raises an exception.
+  def mon_check_owner
+    @mon_data.mon_check_owner
   end
 end
 
-# Use the Monitor class when you want to have a lock object for blocks with
-# mutual exclusion.
-#
-#   require 'monitor'
-#
-#   lock = Monitor.new
-#   lock.synchronize do
-#     # exclusive access
-#   end
-#
-class Monitor
-  include MonitorMixin
-  alias try_enter try_mon_enter
-  alias enter mon_enter
-  alias exit mon_exit
+class Monitor # :nodoc:
+  alias try_mon_enter try_enter
+  alias mon_try_enter try_enter
+  alias mon_enter enter
+  alias mon_exit exit
+  alias mon_synchronize synchronize
 end
 
-
 # Documentation comments:
 #  - All documentation comes from Nutshell.
 #  - MonitorMixin.new_cond appears in the example, but is not documented in
@@ -293,8 +214,3 @@ end
 #    directly in the RDoc output.
 #  - in short, it may be worth changing the code layout in this file to make the
 #    documentation easier
-
-# Local variables:
-# mode: Ruby
-# tab-width: 8
-# End:
diff --git a/lib/mutex_m.rb b/lib/mutex_m.rb
deleted file mode 100644
index 722754b8d5..0000000000
--- a/lib/mutex_m.rb
+++ /dev/null
@@ -1,95 +0,0 @@
-#
-#   mutex_m.rb -
-#       $Release Version: 3.0$
-#       $Revision: 1.7 $
-#       Original from mutex.rb
-#       by Keiju ISHITSUKA(keiju@ishitsuka.com)
-#       modified by matz
-#       patched by akira yamada
-#
-# --
-#   Usage:
-#       require "mutex_m.rb"
-#       obj = Object.new
-#       obj.extend Mutex_m
-#       ...
-#       extended object can be handled like Mutex
-#       or
-#       class Foo
-#         include Mutex_m
-#         ...
-#       end
-#       obj = Foo.new
-#       this obj can be handled like Mutex
-#
-
-require 'thread'
-
-module Mutex_m
-  def Mutex_m.define_aliases(cl)
-    cl.module_eval %q{
-      alias locked? mu_locked?
-      alias lock mu_lock
-      alias unlock mu_unlock
-      alias try_lock mu_try_lock
-      alias synchronize mu_synchronize
-    }
-  end
-
-  def Mutex_m.append_features(cl)
-    super
-    define_aliases(cl) unless cl.instance_of?(Module)
-  end
-
-  def Mutex_m.extend_object(obj)
-    super
-    obj.mu_extended
-  end
-
-  def mu_extended
-    unless (defined? locked? and
-            defined? lock and
-            defined? unlock and
-            defined? try_lock and
-            defined? synchronize)
-      Mutex_m.define_aliases(singleton_class)
-    end
-    mu_initialize
-  end
-
-  # locking
-  def mu_synchronize(&block)
-    @_mutex.synchronize(&block)
-  end
-
-  def mu_locked?
-    @_mutex.locked?
-  end
-
-  def mu_try_lock
-    @_mutex.try_lock
-  end
-
-  def mu_lock
-    @_mutex.lock
-  end
-
-  def mu_unlock
-    @_mutex.unlock
-  end
-
-  def sleep(timeout = nil)
-    @_mutex.sleep(timeout)
-  end
-
-  private
-
-  def mu_initialize
-    @_mutex = Mutex.new
-  end
-
-  def initialize(*args)
-    mu_initialize
-    super
-  end
-end
diff --git a/lib/net/.document b/lib/net/.document
deleted file mode 100644
index 6332bb9e7e..0000000000
--- a/lib/net/.document
+++ /dev/null
@@ -1,8 +0,0 @@
-ftp.rb
-http.rb
-https.rb
-imap.rb
-pop.rb
-smtp.rb
-smtps.rb
-telnet.rb
diff --git a/lib/net/ftp.rb b/lib/net/ftp.rb
deleted file mode 100644
index 149fc6adc1..0000000000
--- a/lib/net/ftp.rb
+++ /dev/null
@@ -1,1043 +0,0 @@
-#
-# = net/ftp.rb - FTP Client Library
-#
-# Written by Shugo Maeda <shugo@ruby-lang.org>.
-#
-# Documentation by Gavin Sinclair, sourced from "Programming Ruby" (Hunt/Thomas)
-# and "Ruby In a Nutshell" (Matsumoto), used with permission.
-#
-# This library is distributed under the terms of the Ruby license.
-# You can freely distribute/modify this library.
-#
-# It is included in the Ruby standard library.
-#
-# See the Net::FTP class for an overview.
-#
-
-require "socket"
-require "monitor"
-
-module Net
-
-  # :stopdoc:
-  class FTPError < StandardError; end
-  class FTPReplyError < FTPError; end
-  class FTPTempError < FTPError; end
-  class FTPPermError < FTPError; end
-  class FTPProtoError < FTPError; end
-  class FTPConnectionError < FTPError; end
-  # :startdoc:
-
-  #
-  # This class implements the File Transfer Protocol.  If you have used a
-  # command-line FTP program, and are familiar with the commands, you will be
-  # able to use this class easily.  Some extra features are included to take
-  # advantage of Ruby's style and strengths.
-  #
-  # == Example
-  #
-  #   require 'net/ftp'
-  #
-  # === Example 1
-  #
-  #   ftp = Net::FTP.new('ftp.netlab.co.jp')
-  #   ftp.login
-  #   files = ftp.chdir('pub/lang/ruby/contrib')
-  #   files = ftp.list('n*')
-  #   ftp.getbinaryfile('nif.rb-0.91.gz', 'nif.gz', 1024)
-  #   ftp.close
-  #
-  # === Example 2
-  #
-  #   Net::FTP.open('ftp.netlab.co.jp') do |ftp|
-  #     ftp.login
-  #     files = ftp.chdir('pub/lang/ruby/contrib')
-  #     files = ftp.list('n*')
-  #     ftp.getbinaryfile('nif.rb-0.91.gz', 'nif.gz', 1024)
-  #   end
-  #
-  # == Major Methods
-  #
-  # The following are the methods most likely to be useful to users:
-  # - FTP.open
-  # - #getbinaryfile
-  # - #gettextfile
-  # - #putbinaryfile
-  # - #puttextfile
-  # - #chdir
-  # - #nlst
-  # - #size
-  # - #rename
-  # - #delete
-  #
-  class FTP
-    include MonitorMixin
-
-    # :stopdoc:
-    FTP_PORT = 21
-    CRLF = "\r\n"
-    DEFAULT_BLOCKSIZE = 4096
-    # :startdoc:
-
-    # When +true+, transfers are performed in binary mode.  Default: +true+.
-    attr_reader :binary
-
-    # When +true+, the connection is in passive mode.  Default: +false+.
-    attr_accessor :passive
-
-    # When +true+, all traffic to and from the server is written
-    # to +$stdout+.  Default: +false+.
-    attr_accessor :debug_mode
-
-    # Sets or retrieves the +resume+ status, which decides whether incomplete
-    # transfers are resumed or restarted.  Default: +false+.
-    attr_accessor :resume
-
-    # The server's welcome message.
-    attr_reader :welcome
-
-    # The server's last response code.
-    attr_reader :last_response_code
-    alias lastresp last_response_code
-
-    # The server's last response.
-    attr_reader :last_response
-
-    #
-    # A synonym for <tt>FTP.new</tt>, but with a mandatory host parameter.
-    #
-    # If a block is given, it is passed the +FTP+ object, which will be closed
-    # when the block finishes, or when an exception is raised.
-    #
-    def FTP.open(host, user = nil, passwd = nil, acct = nil)
-      if block_given?
-        ftp = new(host, user, passwd, acct)
-        begin
-          yield ftp
-        ensure
-          ftp.close
-        end
-      else
-        new(host, user, passwd, acct)
-      end
-    end
-
-    #
-    # Creates and returns a new +FTP+ object. If a +host+ is given, a connection
-    # is made. Additionally, if the +user+ is given, the given user name,
-    # password, and (optionally) account are used to log in.  See #login.
-    #
-    def initialize(host = nil, user = nil, passwd = nil, acct = nil)
-      super()
-      @binary = true
-      @passive = false
-      @debug_mode = false
-      @resume = false
-      @sock = NullSocket.new
-      @logged_in = false
-      if host
-        connect(host)
-        if user
-          login(user, passwd, acct)
-        end
-      end
-    end
-
-    # A setter to toggle transfers in binary mode.
-    # +newmode+ is either +true+ or +false+
-    def binary=(newmode)
-      if newmode != @binary
-        @binary = newmode
-        send_type_command if @logged_in
-      end
-    end
-
-    # Sends a command to destination host, with the current binary sendmode
-    # type.
-    #
-    # If binary mode is +true+, then "TYPE I" (image) is sent, otherwise "TYPE
-    # A" (ascii) is sent.
-    def send_type_command # :nodoc:
-      if @binary
-        voidcmd("TYPE I")
-      else
-        voidcmd("TYPE A")
-      end
-    end
-    private :send_type_command
-
-    # Toggles transfers in binary mode and yields to a block.
-    # This preserves your current binary send mode, but allows a temporary
-    # transaction with binary sendmode of +newmode+.
-    #
-    # +newmode+ is either +true+ or +false+
-    def with_binary(newmode) # :nodoc:
-      oldmode = binary
-      self.binary = newmode
-      begin
-        yield
-      ensure
-        self.binary = oldmode
-      end
-    end
-    private :with_binary
-
-    # Obsolete
-    def return_code # :nodoc:
-      $stderr.puts("warning: Net::FTP#return_code is obsolete and do nothing")
-      return "\n"
-    end
-
-    # Obsolete
-    def return_code=(s) # :nodoc:
-      $stderr.puts("warning: Net::FTP#return_code= is obsolete and do nothing")
-    end
-
-    # Contructs a socket with +host+ and +port+.
-    #
-    # If SOCKSSocket is defined and the environment (ENV) defines
-    # SOCKS_SERVER, then a SOCKSSocket is returned, else a TCPSocket is
-    # returned.
-    def open_socket(host, port) # :nodoc:
-      if defined? SOCKSSocket and ENV["SOCKS_SERVER"]
-        @passive = true
-        return SOCKSSocket.open(host, port)
-      else
-        return TCPSocket.open(host, port)
-      end
-    end
-    private :open_socket
-
-    #
-    # Establishes an FTP connection to host, optionally overriding the default
-    # port. If the environment variable +SOCKS_SERVER+ is set, sets up the
-    # connection through a SOCKS proxy. Raises an exception (typically
-    # <tt>Errno::ECONNREFUSED</tt>) if the connection cannot be established.
-    #
-    def connect(host, port = FTP_PORT)
-      if @debug_mode
-        print "connect: ", host, ", ", port, "\n"
-      end
-      synchronize do
-        @sock = open_socket(host, port)
-        voidresp
-      end
-    end
-
-    #
-    # WRITEME or make private
-    #
-    def set_socket(sock, get_greeting = true)
-      synchronize do
-        @sock = sock
-        if get_greeting
-          voidresp
-        end
-      end
-    end
-
-    # If string +s+ includes the PASS command (password), then the contents of
-    # the password are cleaned from the string using "*"
-    def sanitize(s) # :nodoc:
-      if s =~ /^PASS /i
-        return s[0, 5] + "*" * (s.length - 5)
-      else
-        return s
-      end
-    end
-    private :sanitize
-
-    # Ensures that +line+ has a control return / line feed (CRLF) and writes
-    # it to the socket.
-    def putline(line) # :nodoc:
-      if @debug_mode
-        print "put: ", sanitize(line), "\n"
-      end
-      line = line + CRLF
-      @sock.write(line)
-    end
-    private :putline
-
-    # Reads a line from the sock.  If EOF, then it will raise EOFError
-    def getline # :nodoc:
-      line = @sock.readline # if get EOF, raise EOFError
-      line.sub!(/(\r\n|\n|\r)\z/n, "")
-      if @debug_mode
-        print "get: ", sanitize(line), "\n"
-      end
-      return line
-    end
-    private :getline
-
-    # Receive a section of lines until the response code's match.
-    def getmultiline # :nodoc:
-      line = getline
-      buff = line
-      if line[3] == ?-
-          code = line[0, 3]
-        begin
-          line = getline
-          buff << "\n" << line
-        end until line[0, 3] == code and line[3] != ?-
-      end
-      return buff << "\n"
-    end
-    private :getmultiline
-
-    # Recieves a response from the destination host.
-    #
-    # Returns the response code or raises FTPTempError, FTPPermError, or
-    # FTPProtoError
-    def getresp # :nodoc:
-      @last_response = getmultiline
-      @last_response_code = @last_response[0, 3]
-      case @last_response_code
-      when /\A[123]/
-        return @last_response
-      when /\A4/
-        raise FTPTempError, @last_response
-      when /\A5/
-        raise FTPPermError, @last_response
-      else
-        raise FTPProtoError, @last_response
-      end
-    end
-    private :getresp
-
-    # Recieves a response.
-    #
-    # Raises FTPReplyError if the first position of the response code is not
-    # equal 2.
-    def voidresp # :nodoc:
-      resp = getresp
-      if resp[0] != ?2
-        raise FTPReplyError, resp
-      end
-    end
-    private :voidresp
-
-    #
-    # Sends a command and returns the response.
-    #
-    def sendcmd(cmd)
-      synchronize do
-        putline(cmd)
-        return getresp
-      end
-    end
-
-    #
-    # Sends a command and expect a response beginning with '2'.
-    #
-    def voidcmd(cmd)
-      synchronize do
-        putline(cmd)
-        voidresp
-      end
-    end
-
-    # Constructs and send the appropriate PORT (or EPRT) command
-    def sendport(host, port) # :nodoc:
-      af = (@sock.peeraddr)[0]
-      if af == "AF_INET"
-        cmd = "PORT " + (host.split(".") + port.divmod(256)).join(",")
-      elsif af == "AF_INET6"
-        cmd = sprintf("EPRT |2|%s|%d|", host, port)
-      else
-        raise FTPProtoError, host
-      end
-      voidcmd(cmd)
-    end
-    private :sendport
-
-    # Constructs a TCPServer socket, and sends it the PORT command
-    #
-    # Returns the constructed TCPServer socket
-    def makeport # :nodoc:
-      sock = TCPServer.open(@sock.addr[3], 0)
-      port = sock.addr[1]
-      host = sock.addr[3]
-      sendport(host, port)
-      return sock
-    end
-    private :makeport
-
-    # sends the appropriate command to enable a passive connection
-    def makepasv # :nodoc:
-      if @sock.peeraddr[0] == "AF_INET"
-        host, port = parse227(sendcmd("PASV"))
-      else
-        host, port = parse229(sendcmd("EPSV"))
-        #     host, port = parse228(sendcmd("LPSV"))
-      end
-      return host, port
-    end
-    private :makepasv
-
-    # Constructs a connection for transferring data
-    def transfercmd(cmd, rest_offset = nil) # :nodoc:
-      if @passive
-        host, port = makepasv
-        conn = open_socket(host, port)
-        if @resume and rest_offset
-          resp = sendcmd("REST " + rest_offset.to_s)
-          if resp[0] != ?3
-            raise FTPReplyError, resp
-          end
-        end
-        resp = sendcmd(cmd)
-        # skip 2XX for some ftp servers
-        resp = getresp if resp[0] == ?2
-        if resp[0] != ?1
-          raise FTPReplyError, resp
-        end
-      else
-        sock = makeport
-        if @resume and rest_offset
-          resp = sendcmd("REST " + rest_offset.to_s)
-          if resp[0] != ?3
-            raise FTPReplyError, resp
-          end
-        end
-        resp = sendcmd(cmd)
-        # skip 2XX for some ftp servers
-        resp = getresp if resp[0] == ?2
-        if resp[0] != ?1
-          raise FTPReplyError, resp
-        end
-        conn = sock.accept
-        sock.close
-      end
-      return conn
-    end
-    private :transfercmd
-
-    #
-    # Logs in to the remote host. The session must have been previously
-    # connected.  If +user+ is the string "anonymous" and the +password+ is
-    # +nil+, a password of <tt>user@host</tt> is synthesized. If the +acct+
-    # parameter is not +nil+, an FTP ACCT command is sent following the
-    # successful login.  Raises an exception on error (typically
-    # <tt>Net::FTPPermError</tt>).
-    #
-    def login(user = "anonymous", passwd = nil, acct = nil)
-      if user == "anonymous" and passwd == nil
-        passwd = "anonymous@"
-      end
-
-      resp = ""
-      synchronize do
-        resp = sendcmd('USER ' + user)
-        if resp[0] == ?3
-          raise FTPReplyError, resp if passwd.nil?
-          resp = sendcmd('PASS ' + passwd)
-        end
-        if resp[0] == ?3
-          raise FTPReplyError, resp if acct.nil?
-          resp = sendcmd('ACCT ' + acct)
-        end
-      end
-      if resp[0] != ?2
-        raise FTPReplyError, resp
-      end
-      @welcome = resp
-      send_type_command
-      @logged_in = true
-    end
-
-    #
-    # Puts the connection into binary (image) mode, issues the given command,
-    # and fetches the data returned, passing it to the associated block in
-    # chunks of +blocksize+ characters. Note that +cmd+ is a server command
-    # (such as "RETR myfile").
-    #
-    def retrbinary(cmd, blocksize, rest_offset = nil) # :yield: data
-      synchronize do
-        with_binary(true) do
-          conn = transfercmd(cmd, rest_offset)
-          loop do
-            data = conn.read(blocksize)
-            break if data == nil
-            yield(data)
-          end
-          conn.close
-          voidresp
-        end
-      end
-    end
-
-    #
-    # Puts the connection into ASCII (text) mode, issues the given command, and
-    # passes the resulting data, one line at a time, to the associated block. If
-    # no block is given, prints the lines. Note that +cmd+ is a server command
-    # (such as "RETR myfile").
-    #
-    def retrlines(cmd) # :yield: line
-      synchronize do
-        with_binary(false) do
-          conn = transfercmd(cmd)
-          loop do
-            line = conn.gets
-            break if line == nil
-            yield(line.sub(/\r?\n\z/, ""), !line.match(/\n\z/).nil?)
-          end
-          conn.close
-          voidresp
-        end
-      end
-    end
-
-    #
-    # Puts the connection into binary (image) mode, issues the given server-side
-    # command (such as "STOR myfile"), and sends the contents of the file named
-    # +file+ to the server. If the optional block is given, it also passes it
-    # the data, in chunks of +blocksize+ characters.
-    #
-    def storbinary(cmd, file, blocksize, rest_offset = nil, &block) # :yield: data
-      if rest_offset
-        file.seek(rest_offset, IO::SEEK_SET)
-      end
-      synchronize do
-        with_binary(true) do
-          conn = transfercmd(cmd)
-          loop do
-            buf = file.read(blocksize)
-            break if buf == nil
-            conn.write(buf)
-            yield(buf) if block
-          end
-          conn.close
-          voidresp
-        end
-      end
-    rescue Errno::EPIPE
-      # EPIPE, in this case, means that the data connection was unexpectedly
-      # terminated.  Rather than just raising EPIPE to the caller, check the
-      # response on the control connection.  If getresp doesn't raise a more
-      # appropriate exception, re-raise the original exception.
-      getresp
-      raise
-    end
-
-    #
-    # Puts the connection into ASCII (text) mode, issues the given server-side
-    # command (such as "STOR myfile"), and sends the contents of the file
-    # named +file+ to the server, one line at a time. If the optional block is
-    # given, it also passes it the lines.
-    #
-    def storlines(cmd, file, &block) # :yield: line
-      synchronize do
-        with_binary(false) do
-          conn = transfercmd(cmd)
-          loop do
-            buf = file.gets
-            break if buf == nil
-            if buf[-2, 2] != CRLF
-              buf = buf.chomp + CRLF
-            end
-            conn.write(buf)
-            yield(buf) if block
-          end
-          conn.close
-          voidresp
-        end
-      end
-    rescue Errno::EPIPE
-      # EPIPE, in this case, means that the data connection was unexpectedly
-      # terminated.  Rather than just raising EPIPE to the caller, check the
-      # response on the control connection.  If getresp doesn't raise a more
-      # appropriate exception, re-raise the original exception.
-      getresp
-      raise
-    end
-
-    #
-    # Retrieves +remotefile+ in binary mode, storing the result in +localfile+.
-    # If +localfile+ is nil, returns retrieved data.
-    # If a block is supplied, it is passed the retrieved data in +blocksize+
-    # chunks.
-    #
-    def getbinaryfile(remotefile, localfile = File.basename(remotefile),
-                      blocksize = DEFAULT_BLOCKSIZE) # :yield: data
-      result = nil
-      if localfile
-        if @resume
-          rest_offset = File.size?(localfile)
-          f = open(localfile, "a")
-        else
-          rest_offset = nil
-          f = open(localfile, "w")
-        end
-      elsif !block_given?
-        result = ""
-      end
-      begin
-        f.binmode if localfile
-        retrbinary("RETR " + remotefile.to_s, blocksize, rest_offset) do |data|
-          f.write(data) if localfile
-          yield(data) if block_given?
-          result.concat(data) if result
-        end
-        return result
-      ensure
-        f.close if localfile
-      end
-    end
-
-    #
-    # Retrieves +remotefile+ in ASCII (text) mode, storing the result in
-    # +localfile+.
-    # If +localfile+ is nil, returns retrieved data.
-    # If a block is supplied, it is passed the retrieved data one
-    # line at a time.
-    #
-    def gettextfile(remotefile, localfile = File.basename(remotefile)) # :yield: line
-      result = nil
-      if localfile
-        f = open(localfile, "w")
-      elsif !block_given?
-        result = ""
-      end
-      begin
-        retrlines("RETR " + remotefile) do |line, newline|
-          l = newline ? line + "\n" : line
-          f.print(l) if localfile
-          yield(line, newline) if block_given?
-          result.concat(l) if result
-        end
-        return result
-      ensure
-        f.close if localfile
-      end
-    end
-
-    #
-    # Retrieves +remotefile+ in whatever mode the session is set (text or
-    # binary).  See #gettextfile and #getbinaryfile.
-    #
-    def get(remotefile, localfile = File.basename(remotefile),
-            blocksize = DEFAULT_BLOCKSIZE, &block) # :yield: data
-      if @binary
-        getbinaryfile(remotefile, localfile, blocksize, &block)
-      else
-        gettextfile(remotefile, localfile, &block)
-      end
-    end
-
-    #
-    # Transfers +localfile+ to the server in binary mode, storing the result in
-    # +remotefile+. If a block is supplied, calls it, passing in the transmitted
-    # data in +blocksize+ chunks.
-    #
-    def putbinaryfile(localfile, remotefile = File.basename(localfile),
-                      blocksize = DEFAULT_BLOCKSIZE, &block) # :yield: data
-      if @resume
-        begin
-          rest_offset = size(remotefile)
-        rescue Net::FTPPermError
-          rest_offset = nil
-        end
-      else
-        rest_offset = nil
-      end
-      f = open(localfile)
-      begin
-        f.binmode
-        if rest_offset
-          storbinary("APPE " + remotefile, f, blocksize, rest_offset, &block)
-        else
-          storbinary("STOR " + remotefile, f, blocksize, rest_offset, &block)
-        end
-      ensure
-        f.close
-      end
-    end
-
-    #
-    # Transfers +localfile+ to the server in ASCII (text) mode, storing the result
-    # in +remotefile+. If callback or an associated block is supplied, calls it,
-    # passing in the transmitted data one line at a time.
-    #
-    def puttextfile(localfile, remotefile = File.basename(localfile), &block) # :yield: line
-      f = open(localfile)
-      begin
-        storlines("STOR " + remotefile, f, &block)
-      ensure
-        f.close
-      end
-    end
-
-    #
-    # Transfers +localfile+ to the server in whatever mode the session is set
-    # (text or binary).  See #puttextfile and #putbinaryfile.
-    #
-    def put(localfile, remotefile = File.basename(localfile),
-            blocksize = DEFAULT_BLOCKSIZE, &block)
-      if @binary
-        putbinaryfile(localfile, remotefile, blocksize, &block)
-      else
-        puttextfile(localfile, remotefile, &block)
-      end
-    end
-
-    #
-    # Sends the ACCT command.
-    #
-    # This is a less common FTP command, to send account
-    # information if the destination host requires it.
-    #
-    def acct(account)
-      cmd = "ACCT " + account
-      voidcmd(cmd)
-    end
-
-    #
-    # Returns an array of filenames in the remote directory.
-    #
-    def nlst(dir = nil)
-      cmd = "NLST"
-      if dir
-        cmd = cmd + " " + dir
-      end
-      files = []
-      retrlines(cmd) do |line|
-        files.push(line)
-      end
-      return files
-    end
-
-    #
-    # Returns an array of file information in the directory (the output is like
-    # `ls -l`).  If a block is given, it iterates through the listing.
-    #
-    def list(*args, &block) # :yield: line
-      cmd = "LIST"
-      args.each do |arg|
-        cmd = cmd + " " + arg.to_s
-      end
-      if block
-        retrlines(cmd, &block)
-      else
-        lines = []
-        retrlines(cmd) do |line|
-          lines << line
-        end
-        return lines
-      end
-    end
-    alias ls list
-    alias dir list
-
-    #
-    # Renames a file on the server.
-    #
-    def rename(fromname, toname)
-      resp = sendcmd("RNFR " + fromname)
-      if resp[0] != ?3
-        raise FTPReplyError, resp
-      end
-      voidcmd("RNTO " + toname)
-    end
-
-    #
-    # Deletes a file on the server.
-    #
-    def delete(filename)
-      resp = sendcmd("DELE " + filename)
-      if resp[0, 3] == "250"
-        return
-      elsif resp[0] == ?5
-        raise FTPPermError, resp
-      else
-        raise FTPReplyError, resp
-      end
-    end
-
-    #
-    # Changes the (remote) directory.
-    #
-    def chdir(dirname)
-      if dirname == ".."
-        begin
-          voidcmd("CDUP")
-          return
-        rescue FTPPermError => e
-          if e.message[0, 3] != "500"
-            raise e
-          end
-        end
-      end
-      cmd = "CWD " + dirname
-      voidcmd(cmd)
-    end
-
-    #
-    # Returns the size of the given (remote) filename.
-    #
-    def size(filename)
-      with_binary(true) do
-        resp = sendcmd("SIZE " + filename)
-        if resp[0, 3] != "213"
-          raise FTPReplyError, resp
-        end
-        return resp[3..-1].strip.to_i
-      end
-    end
-
-    MDTM_REGEXP = /^(\d\d\d\d)(\d\d)(\d\d)(\d\d)(\d\d)(\d\d)/  # :nodoc:
-
-    #
-    # Returns the last modification time of the (remote) file.  If +local+ is
-    # +true+, it is returned as a local time, otherwise it's a UTC time.
-    #
-    def mtime(filename, local = false)
-      str = mdtm(filename)
-      ary = str.scan(MDTM_REGEXP)[0].collect {|i| i.to_i}
-      return local ? Time.local(*ary) : Time.gm(*ary)
-    end
-
-    #
-    # Creates a remote directory.
-    #
-    def mkdir(dirname)
-      resp = sendcmd("MKD " + dirname)
-      return parse257(resp)
-    end
-
-    #
-    # Removes a remote directory.
-    #
-    def rmdir(dirname)
-      voidcmd("RMD " + dirname)
-    end
-
-    #
-    # Returns the current remote directory.
-    #
-    def pwd
-      resp = sendcmd("PWD")
-      return parse257(resp)
-    end
-    alias getdir pwd
-
-    #
-    # Returns system information.
-    #
-    def system
-      resp = sendcmd("SYST")
-      if resp[0, 3] != "215"
-        raise FTPReplyError, resp
-      end
-      return resp[4 .. -1]
-    end
-
-    #
-    # Aborts the previous command (ABOR command).
-    #
-    def abort
-      line = "ABOR" + CRLF
-      print "put: ABOR\n" if @debug_mode
-      @sock.send(line, Socket::MSG_OOB)
-      resp = getmultiline
-      unless ["426", "226", "225"].include?(resp[0, 3])
-        raise FTPProtoError, resp
-      end
-      return resp
-    end
-
-    #
-    # Returns the status (STAT command).
-    #
-    def status
-      line = "STAT" + CRLF
-      print "put: STAT\n" if @debug_mode
-      @sock.send(line, Socket::MSG_OOB)
-      return getresp
-    end
-
-    #
-    # Issues the MDTM command.  TODO: more info.
-    #
-    def mdtm(filename)
-      resp = sendcmd("MDTM " + filename)
-      if resp[0, 3] == "213"
-        return resp[3 .. -1].strip
-      end
-    end
-
-    #
-    # Issues the HELP command.
-    #
-    def help(arg = nil)
-      cmd = "HELP"
-      if arg
-        cmd = cmd + " " + arg
-      end
-      sendcmd(cmd)
-    end
-
-    #
-    # Exits the FTP session.
-    #
-    def quit
-      voidcmd("QUIT")
-    end
-
-    #
-    # Issues a NOOP command.
-    #
-    # Does nothing except return a response.
-    #
-    def noop
-      voidcmd("NOOP")
-    end
-
-    #
-    # Issues a SITE command.
-    #
-    def site(arg)
-      cmd = "SITE " + arg
-      voidcmd(cmd)
-    end
-
-    #
-    # Closes the connection.  Further operations are impossible until you open
-    # a new connection with #connect.
-    #
-    def close
-      @sock.close if @sock and not @sock.closed?
-    end
-
-    #
-    # Returns +true+ iff the connection is closed.
-    #
-    def closed?
-      @sock == nil or @sock.closed?
-    end
-
-    # handler for response code 227
-    # (Entering Passive Mode (h1,h2,h3,h4,p1,p2))
-    #
-    # Returns host and port.
-    def parse227(resp) # :nodoc:
-      if resp[0, 3] != "227"
-        raise FTPReplyError, resp
-      end
-      left = resp.index("(")
-      right = resp.index(")")
-      if left == nil or right == nil
-        raise FTPProtoError, resp
-      end
-      numbers = resp[left + 1 .. right - 1].split(",")
-      if numbers.length != 6
-        raise FTPProtoError, resp
-      end
-      host = numbers[0, 4].join(".")
-      port = (numbers[4].to_i << 8) + numbers[5].to_i
-      return host, port
-    end
-    private :parse227
-
-    # handler for response code 228
-    # (Entering Long Passive Mode)
-    #
-    # Returns host and port.
-    def parse228(resp) # :nodoc:
-      if resp[0, 3] != "228"
-        raise FTPReplyError, resp
-      end
-      left = resp.index("(")
-      right = resp.index(")")
-      if left == nil or right == nil
-        raise FTPProtoError, resp
-      end
-      numbers = resp[left + 1 .. right - 1].split(",")
-      if numbers[0] == "4"
-        if numbers.length != 9 || numbers[1] != "4" || numbers[2 + 4] != "2"
-          raise FTPProtoError, resp
-        end
-        host = numbers[2, 4].join(".")
-        port = (numbers[7].to_i << 8) + numbers[8].to_i
-      elsif numbers[0] == "6"
-        if numbers.length != 21 || numbers[1] != "16" || numbers[2 + 16] != "2"
-          raise FTPProtoError, resp
-        end
-        v6 = ["", "", "", "", "", "", "", ""]
-        for i in 0 .. 7
-          v6[i] = sprintf("%02x%02x", numbers[(i * 2) + 2].to_i,
-                          numbers[(i * 2) + 3].to_i)
-        end
-        host = v6[0, 8].join(":")
-        port = (numbers[19].to_i << 8) + numbers[20].to_i
-      end
-      return host, port
-    end
-    private :parse228
-
-    # handler for response code 229
-    # (Extended Passive Mode Entered)
-    #
-    # Returns host and port.
-    def parse229(resp) # :nodoc:
-      if resp[0, 3] != "229"
-        raise FTPReplyError, resp
-      end
-      left = resp.index("(")
-      right = resp.index(")")
-      if left == nil or right == nil
-        raise FTPProtoError, resp
-      end
-      numbers = resp[left + 1 .. right - 1].split(resp[left + 1, 1])
-      if numbers.length != 4
-        raise FTPProtoError, resp
-      end
-      port = numbers[3].to_i
-      host = (@sock.peeraddr())[3]
-      return host, port
-    end
-    private :parse229
-
-    # handler for response code 257
-    # ("PATHNAME" created)
-    #
-    # Returns host and port.
-    def parse257(resp) # :nodoc:
-      if resp[0, 3] != "257"
-        raise FTPReplyError, resp
-      end
-      if resp[3, 2] != ' "'
-        return ""
-      end
-      dirname = ""
-      i = 5
-      n = resp.length
-      while i < n
-        c = resp[i, 1]
-        i = i + 1
-        if c == '"'
-          if i > n or resp[i, 1] != '"'
-            break
-          end
-          i = i + 1
-        end
-        dirname = dirname + c
-      end
-      return dirname
-    end
-    private :parse257
-
-    # :stopdoc:
-    class NullSocket
-      def method_missing(mid, *args)
-        raise FTPConnectionError, "not connected"
-      end
-    end
-    # :startdoc:
-  end
-end
-
-
-# Documentation comments:
-#  - sourced from pickaxe and nutshell, with improvements (hopefully)
-#  - three methods should be private (search WRITEME)
-#  - two methods need more information (search TODO)
diff --git a/lib/net/http.rb b/lib/net/http.rb
index 67de15cd27..53295fe90c 100644
--- a/lib/net/http.rb
+++ b/lib/net/http.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 #
 # = net/http.rb
 #
@@ -21,6 +22,7 @@
 
 require 'net/protocol'
 require 'uri'
+require 'resolv'
 autoload :OpenSSL, 'openssl'
 
 module Net   #:nodoc:
@@ -30,360 +32,719 @@ module Net   #:nodoc:
   class HTTPHeaderSyntaxError < StandardError; end
   # :startdoc:
 
-  # == An HTTP client API for Ruby.
+  # \Class \Net::HTTP provides a rich library that implements the client
+  # in a client-server model that uses the \HTTP request-response protocol.
+  # For information about \HTTP, see:
+  #
+  # - {Hypertext Transfer Protocol}[https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol].
+  # - {Technology}[https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Technology].
+  #
+  # == About the Examples
+  #
+  # :include: doc/net-http/examples.rdoc
+  #
+  # == Strategies
+  #
+  # - If you will make only a few GET requests,
+  #   consider using {OpenURI}[rdoc-ref:OpenURI].
+  # - If you will make only a few requests of all kinds,
+  #   consider using the various singleton convenience methods in this class.
+  #   Each of the following methods automatically starts and finishes
+  #   a {session}[rdoc-ref:Net::HTTP@Sessions] that sends a single request:
+  #
+  #     # Return string response body.
+  #     Net::HTTP.get(hostname, path)
+  #     Net::HTTP.get(uri)
+  #
+  #     # Write string response body to $stdout.
+  #     Net::HTTP.get_print(hostname, path)
+  #     Net::HTTP.get_print(uri)
+  #
+  #     # Return response as Net::HTTPResponse object.
+  #     Net::HTTP.get_response(hostname, path)
+  #     Net::HTTP.get_response(uri)
+  #     data = '{"title": "foo", "body": "bar", "userId": 1}'
+  #     Net::HTTP.post(uri, data)
+  #     params = {title: 'foo', body: 'bar', userId: 1}
+  #     Net::HTTP.post_form(uri, params)
+  #     data = '{"title": "foo", "body": "bar", "userId": 1}'
+  #     Net::HTTP.put(uri, data)
+  #
+  # - If performance is important, consider using sessions, which lower request overhead.
+  #   This {session}[rdoc-ref:Net::HTTP@Sessions] has multiple requests for
+  #   {HTTP methods}[https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Method]
+  #   and {WebDAV methods}[https://en.wikipedia.org/wiki/WebDAV#Implementation]:
+  #
+  #     Net::HTTP.start(hostname) do |http|
+  #       # Session started automatically before block execution.
+  #       http.get(path)
+  #       http.head(path)
+  #       body = 'Some text'
+  #       http.post(path, body)  # Can also have a block.
+  #       http.put(path, body)
+  #       http.delete(path)
+  #       http.options(path)
+  #       http.trace(path)
+  #       http.patch(path, body) # Can also have a block.
+  #       http.copy(path)
+  #       http.lock(path, body)
+  #       http.mkcol(path, body)
+  #       http.move(path)
+  #       http.propfind(path, body)
+  #       http.proppatch(path, body)
+  #       http.unlock(path, body)
+  #       # Session finished automatically at block exit.
+  #     end
   #
-  # Net::HTTP provides a rich library which can be used to build HTTP
-  # user-agents.  For more details about HTTP see
-  # [RFC2616](http://www.ietf.org/rfc/rfc2616.txt)
+  # The methods cited above are convenience methods that, via their few arguments,
+  # allow minimal control over the requests.
+  # For greater control, consider using {request objects}[rdoc-ref:Net::HTTPRequest].
   #
-  # Net::HTTP is designed to work closely with URI.  URI::HTTP#host,
-  # URI::HTTP#port and URI::HTTP#request_uri are designed to work with
-  # Net::HTTP.
+  # == URIs
   #
-  # If you are only performing a few GET requests you should try OpenURI.
+  # On the internet, a URI
+  # ({Universal Resource Identifier}[https://en.wikipedia.org/wiki/Uniform_Resource_Identifier])
+  # is a string that identifies a particular resource.
+  # It consists of some or all of: scheme, hostname, path, query, and fragment;
+  # see {URI syntax}[https://en.wikipedia.org/wiki/Uniform_Resource_Identifier#Syntax].
   #
-  # == Simple Examples
+  # A Ruby {URI::Generic}[rdoc-ref:URI::Generic] object
+  # represents an internet URI.
+  # It provides, among others, methods
+  # +scheme+, +hostname+, +path+, +query+, and +fragment+.
   #
-  # All examples assume you have loaded Net::HTTP with:
+  # === Schemes
   #
-  #   require 'net/http'
+  # An internet \URI has
+  # a {scheme}[https://en.wikipedia.org/wiki/List_of_URI_schemes].
   #
-  # This will also require 'uri' so you don't need to require it separately.
+  # The two schemes supported in \Net::HTTP are <tt>'https'</tt> and <tt>'http'</tt>:
   #
-  # The Net::HTTP methods in the following section do not persist
-  # connections.  They are not recommended if you are performing many HTTP
-  # requests.
+  #   uri.scheme                       # => "https"
+  #   URI('http://example.com').scheme # => "http"
   #
-  # === GET
+  # === Hostnames
   #
-  #   Net::HTTP.get('example.com', '/index.html') # => String
+  # A hostname identifies a server (host) to which requests may be sent:
   #
-  # === GET by URI
+  #   hostname = uri.hostname # => "jsonplaceholder.typicode.com"
+  #   Net::HTTP.start(hostname) do |http|
+  #     # Some HTTP stuff.
+  #   end
   #
-  #   uri = URI('http://example.com/index.html?count=10')
-  #   Net::HTTP.get(uri) # => String
+  # === Paths
   #
-  # === GET with Dynamic Parameters
+  # A host-specific path identifies a resource on the host:
   #
-  #   uri = URI('http://example.com/index.html')
-  #   params = { :limit => 10, :page => 3 }
-  #   uri.query = URI.encode_www_form(params)
+  #   _uri = uri.dup
+  #   _uri.path = '/todos/1'
+  #   hostname = _uri.hostname
+  #   path = _uri.path
+  #   Net::HTTP.get(hostname, path)
   #
-  #   res = Net::HTTP.get_response(uri)
-  #   puts res.body if res.is_a?(Net::HTTPSuccess)
+  # === Queries
   #
-  # === POST
+  # A host-specific query adds name/value pairs to the URI:
   #
-  #   uri = URI('http://www.example.com/search.cgi')
-  #   res = Net::HTTP.post_form(uri, 'q' => 'ruby', 'max' => '50')
-  #   puts res.body
+  #   _uri = uri.dup
+  #   params = {userId: 1, completed: false}
+  #   _uri.query = URI.encode_www_form(params)
+  #   _uri # => #<URI::HTTPS https://jsonplaceholder.typicode.com?userId=1&completed=false>
+  #   Net::HTTP.get(_uri)
   #
-  # === POST with Multiple Values
+  # === Fragments
   #
-  #   uri = URI('http://www.example.com/search.cgi')
-  #   res = Net::HTTP.post_form(uri, 'q' => ['ruby', 'perl'], 'max' => '50')
-  #   puts res.body
+  # A {URI fragment}[https://en.wikipedia.org/wiki/URI_fragment] has no effect
+  # in \Net::HTTP;
+  # the same data is returned, regardless of whether a fragment is included.
   #
-  # == How to use Net::HTTP
+  # == Request Headers
   #
-  # The following example code can be used as the basis of a HTTP user-agent
-  # which can perform a variety of request types using persistent
-  # connections.
+  # Request headers may be used to pass additional information to the host,
+  # similar to arguments passed in a method call;
+  # each header is a name/value pair.
   #
-  #   uri = URI('http://example.com/some_path?query=string')
+  # Each of the \Net::HTTP methods that sends a request to the host
+  # has optional argument +headers+,
+  # where the headers are expressed as a hash of field-name/value pairs:
   #
-  #   Net::HTTP.start(uri.host, uri.port) do |http|
-  #     request = Net::HTTP::Get.new uri.request_uri
+  #   headers = {Accept: 'application/json', Connection: 'Keep-Alive'}
+  #   Net::HTTP.get(uri, headers)
   #
-  #     response = http.request request # Net::HTTPResponse object
-  #   end
+  # See lists of both standard request fields and common request fields at
+  # {Request Fields}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#Request_fields].
+  # A host may also accept other custom fields.
   #
-  # Net::HTTP::start immediately creates a connection to an HTTP server which
-  # is kept open for the duration of the block.  The connection will remain
-  # open for multiple requests in the block if the server indicates it
-  # supports persistent connections.
+  # == \HTTP Sessions
   #
-  # The request types Net::HTTP supports are listed below in the section "HTTP
-  # Request Classes".
+  # A _session_ is a connection between a server (host) and a client that:
   #
-  # If you wish to re-use a connection across multiple HTTP requests without
-  # automatically closing it you can use ::new instead of ::start.  #request
-  # will automatically open a connection to the server if one is not currently
-  # open.  You can manually close the connection with #finish.
+  # - Is begun by instance method Net::HTTP#start.
+  # - May contain any number of requests.
+  # - Is ended by instance method Net::HTTP#finish.
   #
-  # === Response Data
+  # See example sessions at {Strategies}[rdoc-ref:Net::HTTP@Strategies].
   #
-  #   uri = URI('http://example.com/index.html')
-  #   res = Net::HTTP.get_response(uri)
+  # === Session Using \Net::HTTP.start
   #
-  #   # Headers
-  #   res['Set-Cookie']            # => String
-  #   res.get_fields('set-cookie') # => Array
-  #   res.to_hash['set-cookie']    # => Array
-  #   puts "Headers: #{res.to_hash.inspect}"
+  # If you have many requests to make to a single host (and port),
+  # consider using singleton method Net::HTTP.start with a block;
+  # the method handles the session automatically by:
   #
-  #   # Status
-  #   puts res.code       # => '200'
-  #   puts res.message    # => 'OK'
-  #   puts res.class.name # => 'HTTPOK'
+  # - Calling #start before block execution.
+  # - Executing the block.
+  # - Calling #finish after block execution.
   #
-  #   # Body
-  #   puts res.body if res.response_body_permitted?
+  # In the block, you can use these instance methods,
+  # each of which that sends a single request:
   #
-  # === Following Redirection
+  # - {HTTP methods}[https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Method]:
   #
-  # Each Net::HTTPResponse object belongs to a class for its response code.
+  #   - #get, #request_get: GET.
+  #   - #head, #request_head: HEAD.
+  #   - #post, #request_post: POST.
+  #   - #delete: DELETE.
+  #   - #options: OPTIONS.
+  #   - #trace: TRACE.
+  #   - #patch: PATCH.
   #
-  # For example, all 2XX responses are instances of a Net::HTTPSuccess
-  # subclass, a 3XX response is an instance of a Net::HTTPRedirection
-  # subclass and a 200 response is an instance of the Net::HTTPOK class.  For
-  # details of response classes, see the section "HTTP Response Classes"
-  # below.
+  # - {WebDAV methods}[https://en.wikipedia.org/wiki/WebDAV#Implementation]:
   #
-  # Using a case statement you can handle various types of responses properly:
+  #   - #copy: COPY.
+  #   - #lock: LOCK.
+  #   - #mkcol: MKCOL.
+  #   - #move: MOVE.
+  #   - #propfind: PROPFIND.
+  #   - #proppatch: PROPPATCH.
+  #   - #unlock: UNLOCK.
   #
-  #   def fetch(uri_str, limit = 10)
-  #     # You should choose a better exception.
-  #     raise ArgumentError, 'too many HTTP redirects' if limit == 0
+  # === Session Using \Net::HTTP.start and \Net::HTTP.finish
+  #
+  # You can manage a session manually using methods #start and #finish:
+  #
+  #   http = Net::HTTP.new(hostname)
+  #   http.start
+  #   http.get('/todos/1')
+  #   http.get('/todos/2')
+  #   http.delete('/posts/1')
+  #   http.finish # Needed to free resources.
+  #
+  # === Single-Request Session
+  #
+  # Certain convenience methods automatically handle a session by:
+  #
+  # - Creating an \HTTP object
+  # - Starting a session.
+  # - Sending a single request.
+  # - Finishing the session.
+  # - Destroying the object.
+  #
+  # Such methods that send GET requests:
+  #
+  # - ::get: Returns the string response body.
+  # - ::get_print: Writes the string response body to $stdout.
+  # - ::get_response: Returns a Net::HTTPResponse object.
+  #
+  # Such methods that send POST requests:
+  #
+  # - ::post: Posts data to the host.
+  # - ::post_form: Posts form data to the host.
   #
-  #     response = Net::HTTP.get_response(URI(uri_str))
+  # == \HTTP Requests and Responses
   #
-  #     case response
-  #     when Net::HTTPSuccess then
-  #       response
-  #     when Net::HTTPRedirection then
-  #       location = response['location']
-  #       warn "redirected to #{location}"
+  # Many of the methods above are convenience methods,
+  # each of which sends a request and returns a string
+  # without directly using \Net::HTTPRequest and \Net::HTTPResponse objects.
+  #
+  # You can, however, directly create a request object, send the request,
+  # and retrieve the response object; see:
+  #
+  # - Net::HTTPRequest.
+  # - Net::HTTPResponse.
+  #
+  # == Following Redirection
+  #
+  # Each returned response is an instance of a subclass of Net::HTTPResponse.
+  # See the {response class hierarchy}[rdoc-ref:Net::HTTPResponse@Response+Subclasses].
+  #
+  # In particular, class Net::HTTPRedirection is the parent
+  # of all redirection classes.
+  # This allows you to craft a case statement to handle redirections properly:
+  #
+  #   def fetch(uri, limit = 10)
+  #     # You should choose a better exception.
+  #     raise ArgumentError, 'Too many HTTP redirects' if limit == 0
+  #
+  #     res = Net::HTTP.get_response(URI(uri))
+  #     case res
+  #     when Net::HTTPSuccess     # Any success class.
+  #       res
+  #     when Net::HTTPRedirection # Any redirection class.
+  #       location = res['Location']
+  #       warn "Redirected to #{location}"
   #       fetch(location, limit - 1)
-  #     else
-  #       response.value
+  #     else                      # Any other class.
+  #       res.value
   #     end
   #   end
   #
-  #   print fetch('http://www.ruby-lang.org')
-  #
-  # === POST
+  #   fetch(uri)
   #
-  # A POST can be made using the Net::HTTP::Post request class.  This example
-  # creates a urlencoded POST body:
+  # == Basic Authentication
   #
-  #   uri = URI('http://www.example.com/todo.cgi')
-  #   req = Net::HTTP::Post.new(uri.path)
-  #   req.set_form_data('from' => '2005-01-01', 'to' => '2005-03-31')
+  # Basic authentication is performed according to
+  # {RFC2617}[http://www.ietf.org/rfc/rfc2617.txt]:
   #
-  #   res = Net::HTTP.start(uri.hostname, uri.port) do |http|
+  #   req = Net::HTTP::Get.new(uri)
+  #   req.basic_auth('user', 'pass')
+  #   res = Net::HTTP.start(hostname) do |http|
   #     http.request(req)
   #   end
   #
-  #   case res
-  #   when Net::HTTPSuccess, Net::HTTPRedirection
-  #     # OK
-  #   else
-  #     res.value
+  # == Streaming Response Bodies
+  #
+  # By default \Net::HTTP reads an entire response into memory.  If you are
+  # handling large files or wish to implement a progress bar you can instead
+  # stream the body directly to an IO.
+  #
+  #   Net::HTTP.start(hostname) do |http|
+  #     req = Net::HTTP::Get.new(uri)
+  #     http.request(req) do |res|
+  #       open('t.tmp', 'w') do |f|
+  #         res.read_body do |chunk|
+  #           f.write chunk
+  #         end
+  #       end
+  #     end
+  #   end
+  #
+  # == HTTPS
+  #
+  # HTTPS is enabled for an \HTTP connection by Net::HTTP#use_ssl=:
+  #
+  #   Net::HTTP.start(hostname, :use_ssl => true) do |http|
+  #     req = Net::HTTP::Get.new(uri)
+  #     res = http.request(req)
   #   end
   #
-  # At this time Net::HTTP does not support multipart/form-data.  To send
-  # multipart/form-data use Net::HTTPRequest#body= and
-  # Net::HTTPRequest#content_type=:
+  # Or if you simply want to make a GET request, you may pass in a URI
+  # object that has an \HTTPS URL. \Net::HTTP automatically turns on TLS
+  # verification if the URI object has a 'https' URI scheme:
   #
-  #   req = Net::HTTP::Post.new(uri.path)
-  #   req.body = multipart_data
-  #   req.content_type = 'multipart/form-data'
+  #   uri # => #<URI::HTTPS https://jsonplaceholder.typicode.com/>
+  #   Net::HTTP.get(uri)
   #
-  # Other requests that can contain a body such as PUT can be created in the
-  # same way using the corresponding request class (Net::HTTP::Put).
+  # == Proxy Server
   #
-  # === Setting Headers
+  # An \HTTP object can have
+  # a {proxy server}[https://en.wikipedia.org/wiki/Proxy_server].
   #
-  # The following example performs a conditional GET using the
-  # If-Modified-Since header.  If the files has not been modified since the
-  # time in the header a Not Modified response will be returned.  See RFC 2616
-  # section 9.3 for further details.
+  # You can create an \HTTP object with a proxy server
+  # using method Net::HTTP.new or method Net::HTTP.start.
   #
-  #   uri = URI('http://example.com/cached_response')
-  #   file = File.stat 'cached_response'
+  # The proxy may be defined either by argument +p_addr+
+  # or by environment variable <tt>'http_proxy'</tt>.
   #
-  #   req = Net::HTTP::Get.new(uri.request_uri)
-  #   req['If-Modified-Since'] = file.mtime.rfc2822
+  # === Proxy Using Argument +p_addr+ as a \String
   #
-  #   res = Net::HTTP.start(uri.hostname, uri.port) {|http|
-  #     http.request(req)
-  #   }
+  # When argument +p_addr+ is a string hostname,
+  # the returned +http+ has the given host as its proxy:
   #
-  #   open 'cached_response', 'w' do |io|
-  #     io.write res.body
-  #   end if res.is_a?(Net::HTTPSuccess)
+  #   http = Net::HTTP.new(hostname, nil, 'proxy.example')
+  #   http.proxy?          # => true
+  #   http.proxy_from_env? # => false
+  #   http.proxy_address   # => "proxy.example"
+  #   # These use default values.
+  #   http.proxy_port      # => 80
+  #   http.proxy_user      # => nil
+  #   http.proxy_pass      # => nil
   #
-  # === Basic Authentication
+  # The port, username, and password for the proxy may also be given:
   #
-  # Basic authentication is performed according to
-  # [RFC2617](http://www.ietf.org/rfc/rfc2617.txt)
+  #   http = Net::HTTP.new(hostname, nil, 'proxy.example', 8000, 'pname', 'ppass')
+  #   # => #<Net::HTTP jsonplaceholder.typicode.com:80 open=false>
+  #   http.proxy?          # => true
+  #   http.proxy_from_env? # => false
+  #   http.proxy_address   # => "proxy.example"
+  #   http.proxy_port      # => 8000
+  #   http.proxy_user      # => "pname"
+  #   http.proxy_pass      # => "ppass"
   #
-  #   uri = URI('http://example.com/index.html?key=value')
+  # === Proxy Using '<tt>ENV['http_proxy']</tt>'
   #
-  #   req = Net::HTTP::Get.new(uri.request_uri)
-  #   req.basic_auth 'user', 'pass'
+  # When environment variable <tt>'http_proxy'</tt>
+  # is set to a \URI string,
+  # the returned +http+ will have the server at that URI as its proxy;
+  # note that the \URI string must have a protocol
+  # such as <tt>'http'</tt> or <tt>'https'</tt>:
   #
-  #   res = Net::HTTP.start(uri.hostname, uri.port) {|http|
-  #     http.request(req)
-  #   }
-  #   puts res.body
+  #   ENV['http_proxy'] = 'http://example.com'
+  #   http = Net::HTTP.new(hostname)
+  #   http.proxy?          # => true
+  #   http.proxy_from_env? # => true
+  #   http.proxy_address   # => "example.com"
+  #   # These use default values.
+  #   http.proxy_port      # => 80
+  #   http.proxy_user      # => nil
+  #   http.proxy_pass      # => nil
   #
-  # === Streaming Response Bodies
+  # The \URI string may include proxy username, password, and port number:
   #
-  # By default Net::HTTP reads an entire response into memory.  If you are
-  # handling large files or wish to implement a progress bar you can instead
-  # stream the body directly to an IO.
+  #   ENV['http_proxy'] = 'http://pname:ppass@example.com:8000'
+  #   http = Net::HTTP.new(hostname)
+  #   http.proxy?          # => true
+  #   http.proxy_from_env? # => true
+  #   http.proxy_address   # => "example.com"
+  #   http.proxy_port      # => 8000
+  #   http.proxy_user      # => "pname"
+  #   http.proxy_pass      # => "ppass"
   #
-  #   uri = URI('http://example.com/large_file')
+  # === Filtering Proxies
   #
-  #   Net::HTTP.start(uri.host, uri.port) do |http|
-  #     request = Net::HTTP::Get.new uri.request_uri
+  # With method Net::HTTP.new (but not Net::HTTP.start),
+  # you can use argument +p_no_proxy+ to filter proxies:
   #
-  #     http.request request do |response|
-  #       open 'large_file', 'w' do |io|
-  #         response.read_body do |chunk|
-  #           io.write chunk
-  #         end
-  #       end
-  #     end
-  #   end
+  # - Reject a certain address:
   #
-  # === HTTPS
+  #     http = Net::HTTP.new('example.com', nil, 'proxy.example', 8000, 'pname', 'ppass', 'proxy.example')
+  #     http.proxy_address # => nil
   #
-  # HTTPS is enabled for an HTTP connection by Net::HTTP#use_ssl=.
+  # - Reject certain domains or subdomains:
   #
-  #   uri = URI('https://secure.example.com/some_path?query=string')
+  #     http = Net::HTTP.new('example.com', nil, 'my.proxy.example', 8000, 'pname', 'ppass', 'proxy.example')
+  #     http.proxy_address # => nil
   #
-  #   Net::HTTP.start(uri.host, uri.port,
-  #     :use_ssl => uri.scheme == 'https').start do |http|
-  #     request = Net::HTTP::Get.new uri.request_uri
+  # - Reject certain addresses and port combinations:
   #
-  #     response = http.request request # Net::HTTPResponse object
-  #   end
+  #     http = Net::HTTP.new('example.com', nil, 'proxy.example', 8000, 'pname', 'ppass', 'proxy.example:1234')
+  #     http.proxy_address # => "proxy.example"
   #
-  # In previous versions of ruby you would need to require 'net/https' to use
-  # HTTPS.  This is no longer true.
+  #     http = Net::HTTP.new('example.com', nil, 'proxy.example', 8000, 'pname', 'ppass', 'proxy.example:8000')
+  #     http.proxy_address # => nil
+  #
+  # - Reject a list of the types above delimited using a comma:
+  #
+  #     http = Net::HTTP.new('example.com', nil, 'proxy.example', 8000, 'pname', 'ppass', 'my.proxy,proxy.example:8000')
+  #     http.proxy_address # => nil
+  #
+  #     http = Net::HTTP.new('example.com', nil, 'my.proxy', 8000, 'pname', 'ppass', 'my.proxy,proxy.example:8000')
+  #     http.proxy_address # => nil
+  #
+  # == Compression and Decompression
+  #
+  # \Net::HTTP does not compress the body of a request before sending.
+  #
+  # By default, \Net::HTTP adds header <tt>'Accept-Encoding'</tt>
+  # to a new {request object}[rdoc-ref:Net::HTTPRequest]:
+  #
+  #   Net::HTTP::Get.new(uri)['Accept-Encoding']
+  #   # => "gzip;q=1.0,deflate;q=0.6,identity;q=0.3"
+  #
+  # This requests the server to zip-encode the response body if there is one;
+  # the server is not required to do so.
+  #
+  # \Net::HTTP does not automatically decompress a response body
+  # if the response has header <tt>'Content-Range'</tt>.
+  #
+  # Otherwise decompression (or not) depends on the value of header
+  # {Content-Encoding}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#Content-Encoding_2]:
+  #
+  # - <tt>'deflate'</tt>, <tt>'gzip'</tt>, or <tt>'x-gzip'</tt>:
+  #   decompresses the body and deletes the header.
+  # - <tt>'none'</tt> or <tt>'identity'</tt>:
+  #   does not decompress the body, but deletes the header.
+  # - Any other value:
+  #   leaves the body and header unchanged.
+  #
+  # == What's Here
+  #
+  # First, what's elsewhere. Class Net::HTTP:
+  #
+  # - Inherits from {class Object}[rdoc-ref:Object#class-object-whats-here].
+  #
+  # This is a categorized summary of methods and attributes.
+  #
+  # === \Net::HTTP Objects
+  #
+  # - {::new}[rdoc-ref:Net::HTTP.new]:
+  #   Creates a new instance.
+  # - {#inspect}[rdoc-ref:Net::HTTP#inspect]:
+  #   Returns a string representation of +self+.
+  #
+  # === Sessions
+  #
+  # - {::start}[rdoc-ref:Net::HTTP.start]:
+  #   Begins a new session in a new \Net::HTTP object.
+  # - {#started?}[rdoc-ref:Net::HTTP#started?]:
+  #   Returns whether in a session.
+  # - {#finish}[rdoc-ref:Net::HTTP#finish]:
+  #   Ends an active session.
+  # - {#start}[rdoc-ref:Net::HTTP#start]:
+  #   Begins a new session in an existing \Net::HTTP object (+self+).
+  #
+  # === Connections
+  #
+  # - {:continue_timeout}[rdoc-ref:Net::HTTP#continue_timeout]:
+  #   Returns the continue timeout.
+  # - {#continue_timeout=}[rdoc-ref:Net::HTTP#continue_timeout=]:
+  #   Sets the continue timeout seconds.
+  # - {:keep_alive_timeout}[rdoc-ref:Net::HTTP#keep_alive_timeout]:
+  #   Returns the keep-alive timeout.
+  # - {:keep_alive_timeout=}[rdoc-ref:Net::HTTP#keep_alive_timeout=]:
+  #   Sets the keep-alive timeout.
+  # - {:max_retries}[rdoc-ref:Net::HTTP#max_retries]:
+  #   Returns the maximum retries.
+  # - {#max_retries=}[rdoc-ref:Net::HTTP#max_retries=]:
+  #   Sets the maximum retries.
+  # - {:open_timeout}[rdoc-ref:Net::HTTP#open_timeout]:
+  #   Returns the open timeout.
+  # - {:open_timeout=}[rdoc-ref:Net::HTTP#open_timeout=]:
+  #   Sets the open timeout.
+  # - {:read_timeout}[rdoc-ref:Net::HTTP#read_timeout]:
+  #   Returns the open timeout.
+  # - {:read_timeout=}[rdoc-ref:Net::HTTP#read_timeout=]:
+  #   Sets the read timeout.
+  # - {:ssl_timeout}[rdoc-ref:Net::HTTP#ssl_timeout]:
+  #   Returns the ssl timeout.
+  # - {:ssl_timeout=}[rdoc-ref:Net::HTTP#ssl_timeout=]:
+  #   Sets the ssl timeout.
+  # - {:write_timeout}[rdoc-ref:Net::HTTP#write_timeout]:
+  #   Returns the write timeout.
+  # - {write_timeout=}[rdoc-ref:Net::HTTP#write_timeout=]:
+  #   Sets the write timeout.
+  #
+  # === Requests
+  #
+  # - {::get}[rdoc-ref:Net::HTTP.get]:
+  #   Sends a GET request and returns the string response body.
+  # - {::get_print}[rdoc-ref:Net::HTTP.get_print]:
+  #   Sends a GET request and write the string response body to $stdout.
+  # - {::get_response}[rdoc-ref:Net::HTTP.get_response]:
+  #   Sends a GET request and returns a response object.
+  # - {::post_form}[rdoc-ref:Net::HTTP.post_form]:
+  #   Sends a POST request with form data and returns a response object.
+  # - {::post}[rdoc-ref:Net::HTTP.post]:
+  #   Sends a POST request with data and returns a response object.
+  # - {::put}[rdoc-ref:Net::HTTP.put]:
+  #   Sends a PUT request with data and returns a response object.
+  # - {#copy}[rdoc-ref:Net::HTTP#copy]:
+  #   Sends a COPY request and returns a response object.
+  # - {#delete}[rdoc-ref:Net::HTTP#delete]:
+  #   Sends a DELETE request and returns a response object.
+  # - {#get}[rdoc-ref:Net::HTTP#get]:
+  #   Sends a GET request and returns a response object.
+  # - {#head}[rdoc-ref:Net::HTTP#head]:
+  #   Sends a HEAD request and returns a response object.
+  # - {#lock}[rdoc-ref:Net::HTTP#lock]:
+  #   Sends a LOCK request and returns a response object.
+  # - {#mkcol}[rdoc-ref:Net::HTTP#mkcol]:
+  #   Sends a MKCOL request and returns a response object.
+  # - {#move}[rdoc-ref:Net::HTTP#move]:
+  #   Sends a MOVE request and returns a response object.
+  # - {#options}[rdoc-ref:Net::HTTP#options]:
+  #   Sends a OPTIONS request and returns a response object.
+  # - {#patch}[rdoc-ref:Net::HTTP#patch]:
+  #   Sends a PATCH request and returns a response object.
+  # - {#post}[rdoc-ref:Net::HTTP#post]:
+  #   Sends a POST request and returns a response object.
+  # - {#propfind}[rdoc-ref:Net::HTTP#propfind]:
+  #   Sends a PROPFIND request and returns a response object.
+  # - {#proppatch}[rdoc-ref:Net::HTTP#proppatch]:
+  #   Sends a PROPPATCH request and returns a response object.
+  # - {#put}[rdoc-ref:Net::HTTP#put]:
+  #   Sends a PUT request and returns a response object.
+  # - {#request}[rdoc-ref:Net::HTTP#request]:
+  #   Sends a request and returns a response object.
+  # - {#request_get}[rdoc-ref:Net::HTTP#request_get]:
+  #   Sends a GET request and forms a response object;
+  #   if a block given, calls the block with the object,
+  #   otherwise returns the object.
+  # - {#request_head}[rdoc-ref:Net::HTTP#request_head]:
+  #   Sends a HEAD request and forms a response object;
+  #   if a block given, calls the block with the object,
+  #   otherwise returns the object.
+  # - {#request_post}[rdoc-ref:Net::HTTP#request_post]:
+  #   Sends a POST request and forms a response object;
+  #   if a block given, calls the block with the object,
+  #   otherwise returns the object.
+  # - {#send_request}[rdoc-ref:Net::HTTP#send_request]:
+  #   Sends a request and returns a response object.
+  # - {#trace}[rdoc-ref:Net::HTTP#trace]:
+  #   Sends a TRACE request and returns a response object.
+  # - {#unlock}[rdoc-ref:Net::HTTP#unlock]:
+  #   Sends an UNLOCK request and returns a response object.
+  #
+  # === Responses
+  #
+  # - {:close_on_empty_response}[rdoc-ref:Net::HTTP#close_on_empty_response]:
+  #   Returns whether to close connection on empty response.
+  # - {:close_on_empty_response=}[rdoc-ref:Net::HTTP#close_on_empty_response=]:
+  #   Sets whether to close connection on empty response.
+  # - {:ignore_eof}[rdoc-ref:Net::HTTP#ignore_eof]:
+  #   Returns whether to ignore end-of-file when reading a response body
+  #   with <tt>Content-Length</tt> headers.
+  # - {:ignore_eof=}[rdoc-ref:Net::HTTP#ignore_eof=]:
+  #   Sets whether to ignore end-of-file when reading a response body
+  #   with <tt>Content-Length</tt> headers.
+  # - {:response_body_encoding}[rdoc-ref:Net::HTTP#response_body_encoding]:
+  #   Returns the encoding to use for the response body.
+  # - {#response_body_encoding=}[rdoc-ref:Net::HTTP#response_body_encoding=]:
+  #   Sets the response body encoding.
   #
   # === Proxies
   #
-  # Net::HTTP::Proxy has the same methods as Net::HTTP but its instances always
-  # connect via the proxy instead of directly to the given host.
-  #
-  #   proxy_addr = 'your.proxy.host'
-  #   proxy_port = 8080
-  #
-  #   Net::HTTP::Proxy(proxy_addr, proxy_port).start('www.example.com') {|http|
-  #     # always connect to your.proxy.addr:8080
-  #   }
-  #
-  # Net::HTTP::Proxy returns a Net::HTTP instance when proxy_addr is nil so
-  # there is no need for conditional code.
-  #
-  # See Net::HTTP::Proxy for further details and examples such as proxies that
-  # require a username and password.
-  #
-  # == HTTP Request Classes
-  #
-  # Here is the HTTP request class hierarchy.
-  #
-  # * Net::HTTPRequest
-  #   * Net::HTTP::Get
-  #   * Net::HTTP::Head
-  #   * Net::HTTP::Post
-  #   * Net::HTTP::Put
-  #   * Net::HTTP::Proppatch
-  #   * Net::HTTP::Lock
-  #   * Net::HTTP::Unlock
-  #   * Net::HTTP::Options
-  #   * Net::HTTP::Propfind
-  #   * Net::HTTP::Delete
-  #   * Net::HTTP::Move
-  #   * Net::HTTP::Copy
-  #   * Net::HTTP::Mkcol
-  #   * Net::HTTP::Trace
-  #
-  # == HTTP Response Classes
-  #
-  # Here is HTTP response class hierarchy.  All classes are defined in Net
-  # module and are subclasses of Net::HTTPResponse.
-  #
-  # HTTPUnknownResponse:: For unhandled HTTP extensions
-  # HTTPInformation::                    1xx
-  #   HTTPContinue::                        100
-  #   HTTPSwitchProtocol::                  101
-  # HTTPSuccess::                        2xx
-  #   HTTPOK::                              200
-  #   HTTPCreated::                         201
-  #   HTTPAccepted::                        202
-  #   HTTPNonAuthoritativeInformation::     203
-  #   HTTPNoContent::                       204
-  #   HTTPResetContent::                    205
-  #   HTTPPartialContent::                  206
-  # HTTPRedirection::                    3xx
-  #   HTTPMultipleChoice::                  300
-  #   HTTPMovedPermanently::                301
-  #   HTTPFound::                           302
-  #   HTTPSeeOther::                        303
-  #   HTTPNotModified::                     304
-  #   HTTPUseProxy::                        305
-  #   HTTPTemporaryRedirect::               307
-  # HTTPClientError::                    4xx
-  #   HTTPBadRequest::                      400
-  #   HTTPUnauthorized::                    401
-  #   HTTPPaymentRequired::                 402
-  #   HTTPForbidden::                       403
-  #   HTTPNotFound::                        404
-  #   HTTPMethodNotAllowed::                405
-  #   HTTPNotAcceptable::                   406
-  #   HTTPProxyAuthenticationRequired::     407
-  #   HTTPRequestTimeOut::                  408
-  #   HTTPConflict::                        409
-  #   HTTPGone::                            410
-  #   HTTPLengthRequired::                  411
-  #   HTTPPreconditionFailed::              412
-  #   HTTPRequestEntityTooLarge::           413
-  #   HTTPRequestURITooLong::               414
-  #   HTTPUnsupportedMediaType::            415
-  #   HTTPRequestedRangeNotSatisfiable::    416
-  #   HTTPExpectationFailed::               417
-  # HTTPServerError::                    5xx
-  #   HTTPInternalServerError::             500
-  #   HTTPNotImplemented::                  501
-  #   HTTPBadGateway::                      502
-  #   HTTPServiceUnavailable::              503
-  #   HTTPGatewayTimeOut::                  504
-  #   HTTPVersionNotSupported::             505
-  #
-  # There is also the Net::HTTPBadResponse exception which is raised when
-  # there is a protocol error.
+  # - {:proxy_address}[rdoc-ref:Net::HTTP#proxy_address]:
+  #   Returns the proxy address.
+  # - {:proxy_address=}[rdoc-ref:Net::HTTP#proxy_address=]:
+  #   Sets the proxy address.
+  # - {::proxy_class?}[rdoc-ref:Net::HTTP.proxy_class?]:
+  #   Returns whether +self+ is a proxy class.
+  # - {#proxy?}[rdoc-ref:Net::HTTP#proxy?]:
+  #   Returns whether +self+ has a proxy.
+  # - {#proxy_address}[rdoc-ref:Net::HTTP#proxy_address]:
+  #   Returns the proxy address.
+  # - {#proxy_from_env?}[rdoc-ref:Net::HTTP#proxy_from_env?]:
+  #   Returns whether the proxy is taken from an environment variable.
+  # - {:proxy_from_env=}[rdoc-ref:Net::HTTP#proxy_from_env=]:
+  #   Sets whether the proxy is to be taken from an environment variable.
+  # - {:proxy_pass}[rdoc-ref:Net::HTTP#proxy_pass]:
+  #   Returns the proxy password.
+  # - {:proxy_pass=}[rdoc-ref:Net::HTTP#proxy_pass=]:
+  #   Sets the proxy password.
+  # - {:proxy_port}[rdoc-ref:Net::HTTP#proxy_port]:
+  #   Returns the proxy port.
+  # - {:proxy_port=}[rdoc-ref:Net::HTTP#proxy_port=]:
+  #   Sets the proxy port.
+  # - {#proxy_user}[rdoc-ref:Net::HTTP#proxy_user]:
+  #   Returns the proxy user name.
+  # - {:proxy_user=}[rdoc-ref:Net::HTTP#proxy_user=]:
+  #   Sets the proxy user.
+  #
+  # === Security
+  #
+  # - {:ca_file}[rdoc-ref:Net::HTTP#ca_file]:
+  #   Returns the path to a CA certification file.
+  # - {:ca_file=}[rdoc-ref:Net::HTTP#ca_file=]:
+  #   Sets the path to a CA certification file.
+  # - {:ca_path}[rdoc-ref:Net::HTTP#ca_path]:
+  #   Returns the path of to CA directory containing certification files.
+  # - {:ca_path=}[rdoc-ref:Net::HTTP#ca_path=]:
+  #   Sets the path of to CA directory containing certification files.
+  # - {:cert}[rdoc-ref:Net::HTTP#cert]:
+  #   Returns the OpenSSL::X509::Certificate object to be used for client certification.
+  # - {:cert=}[rdoc-ref:Net::HTTP#cert=]:
+  #   Sets the OpenSSL::X509::Certificate object to be used for client certification.
+  # - {:cert_store}[rdoc-ref:Net::HTTP#cert_store]:
+  #   Returns the X509::Store to be used for verifying peer certificate.
+  # - {:cert_store=}[rdoc-ref:Net::HTTP#cert_store=]:
+  #   Sets the X509::Store to be used for verifying peer certificate.
+  # - {:ciphers}[rdoc-ref:Net::HTTP#ciphers]:
+  #   Returns the available SSL ciphers.
+  # - {:ciphers=}[rdoc-ref:Net::HTTP#ciphers=]:
+  #   Sets the available SSL ciphers.
+  # - {:extra_chain_cert}[rdoc-ref:Net::HTTP#extra_chain_cert]:
+  #   Returns the extra X509 certificates to be added to the certificate chain.
+  # - {:extra_chain_cert=}[rdoc-ref:Net::HTTP#extra_chain_cert=]:
+  #   Sets the extra X509 certificates to be added to the certificate chain.
+  # - {:key}[rdoc-ref:Net::HTTP#key]:
+  #   Returns the OpenSSL::PKey::RSA or OpenSSL::PKey::DSA object.
+  # - {:key=}[rdoc-ref:Net::HTTP#key=]:
+  #   Sets the OpenSSL::PKey::RSA or OpenSSL::PKey::DSA object.
+  # - {:max_version}[rdoc-ref:Net::HTTP#max_version]:
+  #   Returns the maximum SSL version.
+  # - {:max_version=}[rdoc-ref:Net::HTTP#max_version=]:
+  #   Sets the maximum SSL version.
+  # - {:min_version}[rdoc-ref:Net::HTTP#min_version]:
+  #   Returns the minimum SSL version.
+  # - {:min_version=}[rdoc-ref:Net::HTTP#min_version=]:
+  #   Sets the minimum SSL version.
+  # - {#peer_cert}[rdoc-ref:Net::HTTP#peer_cert]:
+  #   Returns the X509 certificate chain for the session's socket peer.
+  # - {:ssl_version}[rdoc-ref:Net::HTTP#ssl_version]:
+  #   Returns the SSL version.
+  # - {:ssl_version=}[rdoc-ref:Net::HTTP#ssl_version=]:
+  #   Sets the SSL version.
+  # - {#use_ssl=}[rdoc-ref:Net::HTTP#use_ssl=]:
+  #   Sets whether a new session is to use Transport Layer Security.
+  # - {#use_ssl?}[rdoc-ref:Net::HTTP#use_ssl?]:
+  #   Returns whether +self+ uses SSL.
+  # - {:verify_callback}[rdoc-ref:Net::HTTP#verify_callback]:
+  #   Returns the callback for the server certification verification.
+  # - {:verify_callback=}[rdoc-ref:Net::HTTP#verify_callback=]:
+  #   Sets the callback for the server certification verification.
+  # - {:verify_depth}[rdoc-ref:Net::HTTP#verify_depth]:
+  #   Returns the maximum depth for the certificate chain verification.
+  # - {:verify_depth=}[rdoc-ref:Net::HTTP#verify_depth=]:
+  #   Sets the maximum depth for the certificate chain verification.
+  # - {:verify_hostname}[rdoc-ref:Net::HTTP#verify_hostname]:
+  #   Returns the flags for server the certification verification at the beginning of the SSL/TLS session.
+  # - {:verify_hostname=}[rdoc-ref:Net::HTTP#verify_hostname=]:
+  #   Sets he flags for server the certification verification at the beginning of the SSL/TLS session.
+  # - {:verify_mode}[rdoc-ref:Net::HTTP#verify_mode]:
+  #   Returns the flags for server the certification verification at the beginning of the SSL/TLS session.
+  # - {:verify_mode=}[rdoc-ref:Net::HTTP#verify_mode=]:
+  #   Sets the flags for server the certification verification at the beginning of the SSL/TLS session.
+  #
+  # === Addresses and Ports
+  #
+  # - {:address}[rdoc-ref:Net::HTTP#address]:
+  #   Returns the string host name or host IP.
+  # - {::default_port}[rdoc-ref:Net::HTTP.default_port]:
+  #   Returns integer 80, the default port to use for HTTP requests.
+  # - {::http_default_port}[rdoc-ref:Net::HTTP.http_default_port]:
+  #   Returns integer 80, the default port to use for HTTP requests.
+  # - {::https_default_port}[rdoc-ref:Net::HTTP.https_default_port]:
+  #   Returns integer 443, the default port to use for HTTPS requests.
+  # - {#ipaddr}[rdoc-ref:Net::HTTP#ipaddr]:
+  #   Returns the IP address for the connection.
+  # - {#ipaddr=}[rdoc-ref:Net::HTTP#ipaddr=]:
+  #   Sets the IP address for the connection.
+  # - {:local_host}[rdoc-ref:Net::HTTP#local_host]:
+  #   Returns the string local host used to establish the connection.
+  # - {:local_host=}[rdoc-ref:Net::HTTP#local_host=]:
+  #   Sets the string local host used to establish the connection.
+  # - {:local_port}[rdoc-ref:Net::HTTP#local_port]:
+  #   Returns the integer local port used to establish the connection.
+  # - {:local_port=}[rdoc-ref:Net::HTTP#local_port=]:
+  #   Sets the integer local port used to establish the connection.
+  # - {:port}[rdoc-ref:Net::HTTP#port]:
+  #   Returns the integer port number.
+  #
+  # === \HTTP Version
+  #
+  # - {::version_1_2?}[rdoc-ref:Net::HTTP.version_1_2?]
+  #   (aliased as {::version_1_2}[rdoc-ref:Net::HTTP.version_1_2]):
+  #   Returns true; retained for compatibility.
+  #
+  # === Debugging
+  #
+  # - {#set_debug_output}[rdoc-ref:Net::HTTP#set_debug_output]:
+  #   Sets the output stream for debugging.
   #
   class HTTP < Protocol
 
     # :stopdoc:
-    Revision = %q$Revision$.split[1]
+    VERSION = "0.9.1"
     HTTPVersion = '1.1'
     begin
       require 'zlib'
-      require 'stringio'  #for our purposes (unpacking gzip) lump these together
       HAVE_ZLIB=true
     rescue LoadError
       HAVE_ZLIB=false
     end
     # :startdoc:
 
-    # Turns on net/http 1.2 (ruby 1.8) features.
-    # Defaults to ON in ruby 1.8 or later.
+    # Returns +true+; retained for compatibility.
     def HTTP.version_1_2
       true
     end
 
-    # Returns true if net/http is in version 1.2 mode.
-    # Defaults to true.
+    # Returns +true+; retained for compatibility.
     def HTTP.version_1_2?
       true
     end
 
+    # Returns +false+; retained for compatibility.
     def HTTP.version_1_1?  #:nodoc:
       false
     end
@@ -393,23 +754,14 @@ module Net   #:nodoc:
       alias is_version_1_2? version_1_2?   #:nodoc:
     end
 
+    # :call-seq:
+    #   Net::HTTP.get_print(hostname, path, port = 80) -> nil
+    #   Net::HTTP:get_print(uri, headers = {}, port = uri.port) -> nil
     #
-    # short cut methods
-    #
-
-    #
-    # Gets the body text from the target and outputs it to $stdout.  The
-    # target can either be specified as
-    # (+uri+), or as (+host+, +path+, +port+ = 80); so:
-    #
-    #    Net::HTTP.get_print URI('http://www.example.com/index.html')
-    #
-    # or:
-    #
-    #    Net::HTTP.get_print 'www.example.com', '/index.html'
-    #
-    def HTTP.get_print(uri_or_host, path = nil, port = nil)
-      get_response(uri_or_host, path, port) {|res|
+    # Like Net::HTTP.get, but writes the returned body to $stdout;
+    # returns +nil+.
+    def HTTP.get_print(uri_or_host, path_or_headers = nil, port = nil)
+      get_response(uri_or_host, path_or_headers, port) {|res|
         res.read_body do |chunk|
           $stdout.print chunk
         end
@@ -417,88 +769,185 @@ module Net   #:nodoc:
       nil
     end
 
-    # Sends a GET request to the target and returns the HTTP response
-    # as a string.  The target can either be specified as
-    # (+uri+), or as (+host+, +path+, +port+ = 80); so:
+    # :call-seq:
+    #   Net::HTTP.get(hostname, path, port = 80) -> body
+    #   Net::HTTP:get(uri, headers = {}, port = uri.port) -> body
     #
-    #    print Net::HTTP.get(URI('http://www.example.com/index.html'))
+    # Sends a GET request and returns the \HTTP response body as a string.
     #
-    # or:
+    # With string arguments +hostname+ and +path+:
     #
-    #    print Net::HTTP.get('www.example.com', '/index.html')
+    #   hostname = 'jsonplaceholder.typicode.com'
+    #   path = '/todos/1'
+    #   puts Net::HTTP.get(hostname, path)
     #
-    def HTTP.get(uri_or_host, path = nil, port = nil)
-      get_response(uri_or_host, path, port).body
-    end
-
-    # Sends a GET request to the target and returns the HTTP response
-    # as a Net::HTTPResponse object.  The target can either be specified as
-    # (+uri+), or as (+host+, +path+, +port+ = 80); so:
+    # Output:
+    #
+    #   {
+    #     "userId": 1,
+    #     "id": 1,
+    #     "title": "delectus aut autem",
+    #     "completed": false
+    #   }
     #
-    #    res = Net::HTTP.get_response(URI('http://www.example.com/index.html'))
-    #    print res.body
+    # With URI object +uri+ and optional hash argument +headers+:
     #
-    # or:
+    #   uri = URI('https://jsonplaceholder.typicode.com/todos/1')
+    #   headers = {'Content-type' => 'application/json; charset=UTF-8'}
+    #   Net::HTTP.get(uri, headers)
     #
-    #    res = Net::HTTP.get_response('www.example.com', '/index.html')
-    #    print res.body
+    # Related:
     #
-    def HTTP.get_response(uri_or_host, path = nil, port = nil, &block)
-      if path
+    # - Net::HTTP::Get: request class for \HTTP method +GET+.
+    # - Net::HTTP#get: convenience method for \HTTP method +GET+.
+    #
+    def HTTP.get(uri_or_host, path_or_headers = nil, port = nil)
+      get_response(uri_or_host, path_or_headers, port).body
+    end
+
+    # :call-seq:
+    #   Net::HTTP.get_response(hostname, path, port = 80) -> http_response
+    #   Net::HTTP:get_response(uri, headers = {}, port = uri.port) -> http_response
+    #
+    # Like Net::HTTP.get, but returns a Net::HTTPResponse object
+    # instead of the body string.
+    def HTTP.get_response(uri_or_host, path_or_headers = nil, port = nil, &block)
+      if path_or_headers && !path_or_headers.is_a?(Hash)
         host = uri_or_host
+        path = path_or_headers
         new(host, port || HTTP.default_port).start {|http|
           return http.request_get(path, &block)
         }
       else
         uri = uri_or_host
-        new(uri.hostname, uri.port).start {|http|
-          return http.request_get(uri.request_uri, &block)
+        headers = path_or_headers
+        start(uri.hostname, uri.port,
+              :use_ssl => uri.scheme == 'https') {|http|
+          return http.request_get(uri, headers, &block)
         }
       end
     end
 
-    # Posts HTML form data to the specified URI object.
-    # The form data must be provided as a Hash mapping from String to String.
-    # Example:
+    # Posts data to a host; returns a Net::HTTPResponse object.
     #
-    #   { "cmd" => "search", "q" => "ruby", "max" => "50" }
+    # Argument +url+ must be a URL;
+    # argument +data+ must be a string:
     #
-    # This method also does Basic Authentication iff +url+.user exists.
-    # But userinfo for authentication is deprecated (RFC3986).
-    # So this feature will be removed.
+    #   _uri = uri.dup
+    #   _uri.path = '/posts'
+    #   data = '{"title": "foo", "body": "bar", "userId": 1}'
+    #   headers = {'content-type': 'application/json'}
+    #   res = Net::HTTP.post(_uri, data, headers) # => #<Net::HTTPCreated 201 Created readbody=true>
+    #   puts res.body
     #
-    # Example:
+    # Output:
     #
-    #   require 'net/http'
-    #   require 'uri'
+    #   {
+    #     "title": "foo",
+    #     "body": "bar",
+    #     "userId": 1,
+    #     "id": 101
+    #   }
+    #
+    # Related:
     #
-    #   HTTP.post_form URI('http://www.example.com/search.cgi'),
-    #                  { "q" => "ruby", "max" => "50" }
+    # - Net::HTTP::Post: request class for \HTTP method +POST+.
+    # - Net::HTTP#post: convenience method for \HTTP method +POST+.
+    #
+    def HTTP.post(url, data, header = nil)
+      start(url.hostname, url.port,
+            :use_ssl => url.scheme == 'https' ) {|http|
+        http.post(url, data, header)
+      }
+    end
+
+    # Posts data to a host; returns a Net::HTTPResponse object.
+    #
+    # Argument +url+ must be a URI;
+    # argument +data+ must be a hash:
+    #
+    #   _uri = uri.dup
+    #   _uri.path = '/posts'
+    #   data = {title: 'foo', body: 'bar', userId: 1}
+    #   res = Net::HTTP.post_form(_uri, data) # => #<Net::HTTPCreated 201 Created readbody=true>
+    #   puts res.body
+    #
+    # Output:
+    #
+    #   {
+    #     "title": "foo",
+    #     "body": "bar",
+    #     "userId": "1",
+    #     "id": 101
+    #   }
     #
     def HTTP.post_form(url, params)
-      req = Post.new(url.request_uri)
+      req = Post.new(url)
       req.form_data = params
       req.basic_auth url.user, url.password if url.user
-      new(url.hostname, url.port).start {|http|
+      start(url.hostname, url.port,
+            :use_ssl => url.scheme == 'https' ) {|http|
         http.request(req)
       }
     end
 
+    # Sends a PUT request to the server; returns a Net::HTTPResponse object.
+    #
+    # Argument +url+ must be a URL;
+    # argument +data+ must be a string:
+    #
+    #   _uri = uri.dup
+    #   _uri.path = '/posts'
+    #   data = '{"title": "foo", "body": "bar", "userId": 1}'
+    #   headers = {'content-type': 'application/json'}
+    #   res = Net::HTTP.put(_uri, data, headers) # => #<Net::HTTPCreated 201 Created readbody=true>
+    #   puts res.body
+    #
+    # Output:
+    #
+    #   {
+    #     "title": "foo",
+    #     "body": "bar",
+    #     "userId": 1,
+    #     "id": 101
+    #   }
+    #
+    # Related:
+    #
+    # - Net::HTTP::Put: request class for \HTTP method +PUT+.
+    # - Net::HTTP#put: convenience method for \HTTP method +PUT+.
+    #
+    def HTTP.put(url, data, header = nil)
+      start(url.hostname, url.port,
+            :use_ssl => url.scheme == 'https' ) {|http|
+        http.put(url, data, header)
+      }
+    end
+
     #
-    # HTTP session management
+    # \HTTP session management
     #
 
-    # The default port to use for HTTP requests; defaults to 80.
+    # Returns integer +80+, the default port to use for \HTTP requests:
+    #
+    #   Net::HTTP.default_port # => 80
+    #
     def HTTP.default_port
       http_default_port()
     end
 
-    # The default port to use for HTTP requests; defaults to 80.
+    # Returns integer +80+, the default port to use for \HTTP requests:
+    #
+    #   Net::HTTP.http_default_port # => 80
+    #
     def HTTP.http_default_port
       80
     end
 
-    # The default port to use for HTTPS requests; defaults to 443.
+    # Returns integer +443+, the default port to use for HTTPS requests:
+    #
+    #   Net::HTTP.https_default_port # => 443
+    #
     def HTTP.https_default_port
       443
     end
@@ -507,41 +956,99 @@ module Net   #:nodoc:
       BufferedIO
     end
 
-    # call-seq:
-    #   HTTP.start(address, port, p_addr, p_port, p_user, p_pass, &block)
-    #   HTTP.start(address, port=nil, p_addr=nil, p_port=nil, p_user=nil, p_pass=nil, opt, &block)
-    #
-    # Creates a new Net::HTTP object, then additionally opens the TCP
-    # connection and HTTP session.
-    #
-    # Arguments are the following:
-    # _address_ :: hostname or IP address of the server
-    # _port_    :: port of the server
-    # _p_addr_  :: address of proxy
-    # _p_port_  :: port of proxy
-    # _p_user_  :: user of proxy
-    # _p_pass_  :: pass of proxy
-    # _opt_     :: optional hash
-    #
-    # _opt_ sets following values by its accessor.
-    # The keys are ca_file, ca_path, cert, cert_store, ciphers,
-    # close_on_empty_response, key, open_timeout, read_timeout, ssl_timeout,
-    # ssl_version, use_ssl, verify_callback, verify_depth and verify_mode.
-    # If you set :use_ssl as true, you can use https and default value of
-    # verify_mode is set as OpenSSL::SSL::VERIFY_PEER.
-    #
-    # If the optional block is given, the newly
-    # created Net::HTTP object is passed to it and closed when the
-    # block finishes.  In this case, the return value of this method
-    # is the return value of the block.  If no block is given, the
-    # return value of this method is the newly created Net::HTTP object
-    # itself, and the caller is responsible for closing it upon completion
-    # using the finish() method.
+    # :call-seq:
+    #   HTTP.start(address, port = nil, p_addr = :ENV, p_port = nil, p_user = nil, p_pass = nil, opts) -> http
+    #   HTTP.start(address, port = nil, p_addr = :ENV, p_port = nil, p_user = nil, p_pass = nil, opts) {|http| ... } -> object
+    #
+    # Creates a new \Net::HTTP object, +http+, via \Net::HTTP.new:
+    #
+    # - For arguments +address+ and +port+, see Net::HTTP.new.
+    # - For proxy-defining arguments +p_addr+ through +p_pass+,
+    #   see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
+    # - For argument +opts+, see below.
+    #
+    # With no block given:
+    #
+    # - Calls <tt>http.start</tt> with no block (see #start),
+    #   which opens a TCP connection and \HTTP session.
+    # - Returns +http+.
+    # - The caller should call #finish to close the session:
+    #
+    #     http = Net::HTTP.start(hostname)
+    #     http.started? # => true
+    #     http.finish
+    #     http.started? # => false
+    #
+    # With a block given:
+    #
+    # - Calls <tt>http.start</tt> with the block (see #start), which:
+    #
+    #   - Opens a TCP connection and \HTTP session.
+    #   - Calls the block,
+    #     which may make any number of requests to the host.
+    #   - Closes the \HTTP session and TCP connection on block exit.
+    #   - Returns the block's value +object+.
+    #
+    # - Returns +object+.
+    #
+    # Example:
+    #
+    #   hostname = 'jsonplaceholder.typicode.com'
+    #   Net::HTTP.start(hostname) do |http|
+    #     puts http.get('/todos/1').body
+    #     puts http.get('/todos/2').body
+    #   end
+    #
+    # Output:
+    #
+    #   {
+    #     "userId": 1,
+    #     "id": 1,
+    #     "title": "delectus aut autem",
+    #     "completed": false
+    #   }
+    #   {
+    #     "userId": 1,
+    #     "id": 2,
+    #     "title": "quis ut nam facilis et officia qui",
+    #     "completed": false
+    #   }
+    #
+    # If the last argument given is a hash, it is the +opts+ hash,
+    # where each key is a method or accessor to be called,
+    # and its value is the value to be set.
+    #
+    # The keys may include:
+    #
+    # - #ca_file
+    # - #ca_path
+    # - #cert
+    # - #cert_store
+    # - #ciphers
+    # - #close_on_empty_response
+    # - +ipaddr+ (calls #ipaddr=)
+    # - #keep_alive_timeout
+    # - #key
+    # - #open_timeout
+    # - #read_timeout
+    # - #ssl_timeout
+    # - #ssl_version
+    # - +use_ssl+ (calls #use_ssl=)
+    # - #verify_callback
+    # - #verify_depth
+    # - #verify_mode
+    # - #write_timeout
+    #
+    # Note: If +port+ is +nil+ and <tt>opts[:use_ssl]</tt> is a truthy value,
+    # the value passed to +new+ is Net::HTTP.https_default_port, not +port+.
+    #
     def HTTP.start(address, *arg, &block) # :yield: +http+
       arg.pop if opt = Hash.try_convert(arg[-1])
       port, p_addr, p_port, p_user, p_pass = *arg
+      p_addr = :ENV if arg.size < 2
       port = https_default_port if !port && opt && opt[:use_ssl]
       http = new(address, port, p_addr, p_port, p_user, p_pass)
+      http.ipaddr = opt[:ipaddr] if opt && opt[:ipaddr]
 
       if opt
         if opt[:use_ssl]
@@ -558,44 +1065,144 @@ module Net   #:nodoc:
     end
 
     class << HTTP
-      alias newobj new
+      alias newobj new # :nodoc:
     end
 
-    # Creates a new Net::HTTP object without opening a TCP connection or
-    # HTTP session.
-    # The +address+ should be a DNS hostname or IP address.
-    # If +p_addr+ is given, creates a Net::HTTP object with proxy support.
-    def HTTP.new(address, port = nil, p_addr = nil, p_port = nil, p_user = nil, p_pass = nil)
-      Proxy(p_addr, p_port, p_user, p_pass).newobj(address, port)
+    # Returns a new \Net::HTTP object +http+
+    # (but does not open a TCP connection or \HTTP session).
+    #
+    # With only string argument +address+ given
+    # (and <tt>ENV['http_proxy']</tt> undefined or +nil+),
+    # the returned +http+:
+    #
+    # - Has the given address.
+    # - Has the default port number, Net::HTTP.default_port (80).
+    # - Has no proxy.
+    #
+    # Example:
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   # => #<Net::HTTP jsonplaceholder.typicode.com:80 open=false>
+    #   http.address # => "jsonplaceholder.typicode.com"
+    #   http.port    # => 80
+    #   http.proxy?  # => false
+    #
+    # With integer argument +port+ also given,
+    # the returned +http+ has the given port:
+    #
+    #   http = Net::HTTP.new(hostname, 8000)
+    #   # => #<Net::HTTP jsonplaceholder.typicode.com:8000 open=false>
+    #   http.port # => 8000
+    #
+    # For proxy-defining arguments +p_addr+ through +p_no_proxy+,
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
+    #
+    def HTTP.new(address, port = nil, p_addr = :ENV, p_port = nil, p_user = nil, p_pass = nil, p_no_proxy = nil, p_use_ssl = nil)
+      http = super address, port
+
+      if proxy_class? then # from Net::HTTP::Proxy()
+        http.proxy_from_env = @proxy_from_env
+        http.proxy_address  = @proxy_address
+        http.proxy_port     = @proxy_port
+        http.proxy_user     = @proxy_user
+        http.proxy_pass     = @proxy_pass
+        http.proxy_use_ssl  = @proxy_use_ssl
+      elsif p_addr == :ENV then
+        http.proxy_from_env = true
+      else
+        if p_addr && p_no_proxy && !URI::Generic.use_proxy?(address, address, port, p_no_proxy)
+          p_addr = nil
+          p_port = nil
+        end
+        http.proxy_address = p_addr
+        http.proxy_port    = p_port || default_port
+        http.proxy_user    = p_user
+        http.proxy_pass    = p_pass
+        http.proxy_use_ssl = p_use_ssl
+      end
+
+      http
     end
 
-    # Creates a new Net::HTTP object for the specified server address,
-    # without opening the TCP connection or initializing the HTTP session.
+    class << HTTP
+      # Allows to set the default configuration that will be used
+      # when creating a new connection.
+      #
+      # Example:
+      #
+      #   Net::HTTP.default_configuration = {
+      #     read_timeout: 1,
+      #     write_timeout: 1
+      #   }
+      #   http = Net::HTTP.new(hostname)
+      #   http.open_timeout   # => 60
+      #   http.read_timeout   # => 1
+      #   http.write_timeout  # => 1
+      #
+      attr_accessor :default_configuration
+    end
+
+    # Creates a new \Net::HTTP object for the specified server address,
+    # without opening the TCP connection or initializing the \HTTP session.
     # The +address+ should be a DNS hostname or IP address.
-    def initialize(address, port = nil)
+    def initialize(address, port = nil) # :nodoc:
+      defaults = {
+        keep_alive_timeout: 2,
+        close_on_empty_response: false,
+        open_timeout: 60,
+        read_timeout: 60,
+        write_timeout: 60,
+        continue_timeout: nil,
+        max_retries: 1,
+        debug_output: nil,
+        response_body_encoding: false,
+        ignore_eof: true
+      }
+      options = defaults.merge(self.class.default_configuration || {})
+
       @address = address
       @port    = (port || HTTP.default_port)
+      @ipaddr = nil
+      @local_host = nil
+      @local_port = nil
       @curr_http_version = HTTPVersion
-      @no_keepalive_server = false
-      @close_on_empty_response = false
+      @keep_alive_timeout = options[:keep_alive_timeout]
+      @last_communicated = nil
+      @close_on_empty_response = options[:close_on_empty_response]
       @socket  = nil
       @started = false
-      @open_timeout = nil
-      @read_timeout = 60
-      @continue_timeout = nil
-      @debug_output = nil
+      @open_timeout = options[:open_timeout]
+      @read_timeout = options[:read_timeout]
+      @write_timeout = options[:write_timeout]
+      @continue_timeout = options[:continue_timeout]
+      @max_retries = options[:max_retries]
+      @debug_output = options[:debug_output]
+      @response_body_encoding = options[:response_body_encoding]
+      @ignore_eof = options[:ignore_eof]
+      @tcpsocket_supports_open_timeout = nil
+
+      @proxy_from_env = false
+      @proxy_uri      = nil
+      @proxy_address  = nil
+      @proxy_port     = nil
+      @proxy_user     = nil
+      @proxy_pass     = nil
+      @proxy_use_ssl  = nil
+
       @use_ssl = false
       @ssl_context = nil
-      @enable_post_connection_check = true
-      @compression = nil
+      @ssl_session = nil
       @sspi_enabled = false
-      if defined?(SSL_ATTRIBUTES)
-        SSL_ATTRIBUTES.each do |name|
-          instance_variable_set "@#{name}", nil
-        end
+      SSL_IVNAMES.each do |ivname|
+        instance_variable_set ivname, nil
       end
     end
 
+    # Returns a string representation of +self+:
+    #
+    #   Net::HTTP.new(hostname).inspect
+    #   # => "#<Net::HTTP jsonplaceholder.typicode.com:80 open=false>"
+    #
     def inspect
       "#<#{self.class} #{@address}:#{@port} open=#{started?}>"
     end
@@ -603,70 +1210,303 @@ module Net   #:nodoc:
     # *WARNING* This method opens a serious security hole.
     # Never use this method in production code.
     #
-    # Sets an output stream for debugging.
-    #
-    #   http = Net::HTTP.new
-    #   http.set_debug_output $stderr
-    #   http.start { .... }
+    # Sets the output stream for debugging:
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   File.open('t.tmp', 'w') do |file|
+    #     http.set_debug_output(file)
+    #     http.start
+    #     http.get('/nosuch/1')
+    #     http.finish
+    #   end
+    #   puts File.read('t.tmp')
+    #
+    # Output:
+    #
+    #   opening connection to jsonplaceholder.typicode.com:80...
+    #   opened
+    #   <- "GET /nosuch/1 HTTP/1.1\r\nAccept-Encoding: gzip;q=1.0,deflate;q=0.6,identity;q=0.3\r\nAccept: */*\r\nUser-Agent: Ruby\r\nHost: jsonplaceholder.typicode.com\r\n\r\n"
+    #   -> "HTTP/1.1 404 Not Found\r\n"
+    #   -> "Date: Mon, 12 Dec 2022 21:14:11 GMT\r\n"
+    #   -> "Content-Type: application/json; charset=utf-8\r\n"
+    #   -> "Content-Length: 2\r\n"
+    #   -> "Connection: keep-alive\r\n"
+    #   -> "X-Powered-By: Express\r\n"
+    #   -> "X-Ratelimit-Limit: 1000\r\n"
+    #   -> "X-Ratelimit-Remaining: 999\r\n"
+    #   -> "X-Ratelimit-Reset: 1670879660\r\n"
+    #   -> "Vary: Origin, Accept-Encoding\r\n"
+    #   -> "Access-Control-Allow-Credentials: true\r\n"
+    #   -> "Cache-Control: max-age=43200\r\n"
+    #   -> "Pragma: no-cache\r\n"
+    #   -> "Expires: -1\r\n"
+    #   -> "X-Content-Type-Options: nosniff\r\n"
+    #   -> "Etag: W/\"2-vyGp6PvFo4RvsFtPoIWeCReyIC8\"\r\n"
+    #   -> "Via: 1.1 vegur\r\n"
+    #   -> "CF-Cache-Status: MISS\r\n"
+    #   -> "Server-Timing: cf-q-config;dur=1.3000000762986e-05\r\n"
+    #   -> "Report-To: {\"endpoints\":[{\"url\":\"https:\\/\\/a.nel.cloudflare.com\\/report\\/v3?s=yOr40jo%2BwS1KHzhTlVpl54beJ5Wx2FcG4gGV0XVrh3X9OlR5q4drUn2dkt5DGO4GDcE%2BVXT7CNgJvGs%2BZleIyMu8CLieFiDIvOviOY3EhHg94m0ZNZgrEdpKD0S85S507l1vsEwEHkoTm%2Ff19SiO\"}],\"group\":\"cf-nel\",\"max_age\":604800}\r\n"
+    #   -> "NEL: {\"success_fraction\":0,\"report_to\":\"cf-nel\",\"max_age\":604800}\r\n"
+    #   -> "Server: cloudflare\r\n"
+    #   -> "CF-RAY: 778977dc484ce591-DFW\r\n"
+    #   -> "alt-svc: h3=\":443\"; ma=86400, h3-29=\":443\"; ma=86400\r\n"
+    #   -> "\r\n"
+    #   reading 2 bytes...
+    #   -> "{}"
+    #   read 2 bytes
+    #   Conn keep-alive
     #
     def set_debug_output(output)
-      warn 'Net::HTTP#set_debug_output called after HTTP started' if started?
+      warn 'Net::HTTP#set_debug_output called after HTTP started', uplevel: 1 if started?
       @debug_output = output
     end
 
-    # The DNS host name or IP address to connect to.
+    # Returns the string host name or host IP given as argument +address+ in ::new.
     attr_reader :address
 
-    # The port number to connect to.
+    # Returns the integer port number given as argument +port+ in ::new.
     attr_reader :port
 
-    # Number of seconds to wait for the connection to open. Any number
-    # may be used, including Floats for fractional seconds. If the HTTP
-    # object cannot open a connection in this many seconds, it raises a
-    # TimeoutError exception. The default value is +nil+.
+    # Sets or returns the string local host used to establish the connection;
+    # initially +nil+.
+    attr_accessor :local_host
+
+    # Sets or returns the integer local port used to establish the connection;
+    # initially +nil+.
+    attr_accessor :local_port
+
+    # Returns the encoding to use for the response body;
+    # see #response_body_encoding=.
+    attr_reader :response_body_encoding
+
+    # Sets the encoding to be used for the response body;
+    # returns the encoding.
+    #
+    # The given +value+ may be:
+    #
+    # - An Encoding object.
+    # - The name of an encoding.
+    # - An alias for an encoding name.
+    #
+    # See {Encoding}[rdoc-ref:Encoding].
+    #
+    # Examples:
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.response_body_encoding = Encoding::US_ASCII # => #<Encoding:US-ASCII>
+    #   http.response_body_encoding = 'US-ASCII'         # => "US-ASCII"
+    #   http.response_body_encoding = 'ASCII'            # => "ASCII"
+    #
+    def response_body_encoding=(value)
+      value = Encoding.find(value) if value.is_a?(String)
+      @response_body_encoding = value
+    end
+
+    # Sets whether to determine the proxy from environment variable
+    # '<tt>ENV['http_proxy']</tt>';
+    # see {Proxy Using ENV['http_proxy']}[rdoc-ref:Net::HTTP@Proxy+Using+ENVHTTPProxy].
+    attr_writer :proxy_from_env
+
+    # Sets the proxy address;
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
+    attr_writer :proxy_address
+
+    # Sets the proxy port;
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
+    attr_writer :proxy_port
+
+    # Sets the proxy user;
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
+    attr_writer :proxy_user
+
+    # Sets the proxy password;
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
+    attr_writer :proxy_pass
+
+    # Sets whether the proxy uses SSL;
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
+    attr_writer :proxy_use_ssl
+
+    # Returns the IP address for the connection.
+    #
+    # If the session has not been started,
+    # returns the value set by #ipaddr=,
+    # or +nil+ if it has not been set:
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.ipaddr # => nil
+    #   http.ipaddr = '172.67.155.76'
+    #   http.ipaddr # => "172.67.155.76"
+    #
+    # If the session has been started,
+    # returns the IP address from the socket:
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.start
+    #   http.ipaddr # => "172.67.155.76"
+    #   http.finish
+    #
+    def ipaddr
+      started? ?  @socket.io.peeraddr[3] : @ipaddr
+    end
+
+    # Sets the IP address for the connection:
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.ipaddr # => nil
+    #   http.ipaddr = '172.67.155.76'
+    #   http.ipaddr # => "172.67.155.76"
+    #
+    # The IP address may not be set if the session has been started.
+    def ipaddr=(addr)
+      raise IOError, "ipaddr value changed, but session already started" if started?
+      @ipaddr = addr
+    end
+
+    # Sets or returns the numeric (\Integer or \Float) number of seconds
+    # to wait for a connection to open;
+    # initially 60.
+    # If the connection is not made in the given interval,
+    # an exception is raised.
     attr_accessor :open_timeout
 
-    # Number of seconds to wait for one block to be read (via one read(2)
-    # call). Any number may be used, including Floats for fractional
-    # seconds. If the HTTP object cannot read data in this many seconds,
-    # it raises a TimeoutError exception. The default value is 60 seconds.
+    # Returns the numeric (\Integer or \Float) number of seconds
+    # to wait for one block to be read (via one read(2) call);
+    # see #read_timeout=.
     attr_reader :read_timeout
 
-    # Setter for the read_timeout attribute.
+    # Returns the numeric (\Integer or \Float) number of seconds
+    # to wait for one block to be written (via one write(2) call);
+    # see #write_timeout=.
+    attr_reader :write_timeout
+
+    # Sets the maximum number of times to retry an idempotent request in case of
+    # \Net::ReadTimeout, IOError, EOFError, Errno::ECONNRESET,
+    # Errno::ECONNABORTED, Errno::EPIPE, OpenSSL::SSL::SSLError,
+    # Timeout::Error.
+    # The initial value is 1.
+    #
+    # Argument +retries+ must be a non-negative numeric value:
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.max_retries = 2   # => 2
+    #   http.max_retries       # => 2
+    #
+    def max_retries=(retries)
+      retries = retries.to_int
+      if retries < 0
+        raise ArgumentError, 'max_retries should be non-negative integer number'
+      end
+      @max_retries = retries
+    end
+
+    # Returns the maximum number of times to retry an idempotent request;
+    # see #max_retries=.
+    attr_reader :max_retries
+
+    # Sets the read timeout, in seconds, for +self+ to integer +sec+;
+    # the initial value is 60.
+    #
+    # Argument +sec+ must be a non-negative numeric value:
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.read_timeout # => 60
+    #   http.get('/todos/1') # => #<Net::HTTPOK 200 OK readbody=true>
+    #   http.read_timeout = 0
+    #   http.get('/todos/1') # Raises Net::ReadTimeout.
+    #
     def read_timeout=(sec)
       @socket.read_timeout = sec if @socket
       @read_timeout = sec
     end
 
-    # Seconds to wait for 100 Continue response. If the HTTP object does not
-    # receive a response in this many seconds it sends the request body. The
-    # default value is +nil+.
+    # Sets the write timeout, in seconds, for +self+ to integer +sec+;
+    # the initial value is 60.
+    #
+    # Argument +sec+ must be a non-negative numeric value:
+    #
+    #   _uri = uri.dup
+    #   _uri.path = '/posts'
+    #   body = 'bar' * 200000
+    #   data = <<EOF
+    #   {"title": "foo", "body": "#{body}", "userId": "1"}
+    #   EOF
+    #   headers = {'content-type': 'application/json'}
+    #   http = Net::HTTP.new(hostname)
+    #   http.write_timeout # => 60
+    #   http.post(_uri.path, data, headers)
+    #   # => #<Net::HTTPCreated 201 Created readbody=true>
+    #   http.write_timeout = 0
+    #   http.post(_uri.path, data, headers) # Raises Net::WriteTimeout.
+    #
+    def write_timeout=(sec)
+      @socket.write_timeout = sec if @socket
+      @write_timeout = sec
+    end
+
+    # Returns the continue timeout value;
+    # see continue_timeout=.
     attr_reader :continue_timeout
 
-    # Setter for the continue_timeout attribute.
+    # Sets the continue timeout value,
+    # which is the number of seconds to wait for an expected 100 Continue response.
+    # If the \HTTP object does not receive a response in this many seconds
+    # it sends the request body.
     def continue_timeout=(sec)
       @socket.continue_timeout = sec if @socket
       @continue_timeout = sec
     end
 
-    # Returns true if the HTTP session has been started.
+    # Sets or returns the numeric (\Integer or \Float) number of seconds
+    # to keep the connection open after a request is sent;
+    # initially 2.
+    # If a new request is made during the given interval,
+    # the still-open connection is used;
+    # otherwise the connection will have been closed
+    # and a new connection is opened.
+    attr_accessor :keep_alive_timeout
+
+    # Sets or returns whether to ignore end-of-file when reading a response body
+    # with <tt>Content-Length</tt> headers;
+    # initially +true+.
+    attr_accessor :ignore_eof
+
+    # Returns +true+ if the \HTTP session has been started:
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.started? # => false
+    #   http.start
+    #   http.started? # => true
+    #   http.finish # => nil
+    #   http.started? # => false
+    #
+    #   Net::HTTP.start(hostname) do |http|
+    #     http.started?
+    #   end # => true
+    #   http.started? # => false
+    #
     def started?
       @started
     end
 
     alias active? started?   #:nodoc: obsolete
 
+    # Sets or returns whether to close the connection when the response is empty;
+    # initially +false+.
     attr_accessor :close_on_empty_response
 
-    # Returns true if SSL/TLS is being used with HTTP.
+    # Returns +true+ if +self+ uses SSL, +false+ otherwise.
+    # See Net::HTTP#use_ssl=.
     def use_ssl?
       @use_ssl
     end
 
-    # Turn on/off SSL.
-    # This flag must be set before starting session.
-    # If you change use_ssl value after session started,
-    # a Net::HTTP object raises IOError.
+    # Sets whether a new session is to use
+    # {Transport Layer Security}[https://en.wikipedia.org/wiki/Transport_Layer_Security]:
+    #
+    # Raises IOError if attempting to change during a session.
+    #
+    # Raises OpenSSL::SSL::SSLError if the port is not an HTTPS port.
     def use_ssl=(flag)
       flag = flag ? true : false
       if started? and @use_ssl != flag
@@ -675,53 +1515,85 @@ module Net   #:nodoc:
       @use_ssl = flag
     end
 
-    SSL_ATTRIBUTES = %w(
-      ssl_version key cert ca_file ca_path cert_store ciphers
-      verify_mode verify_callback verify_depth ssl_timeout
-    )
-
-    # Sets path of a CA certification file in PEM format.
-    #
-    # The file can contain several CA certificates.
+    SSL_ATTRIBUTES = [
+      :ca_file,
+      :ca_path,
+      :cert,
+      :cert_store,
+      :ciphers,
+      :extra_chain_cert,
+      :key,
+      :ssl_timeout,
+      :ssl_version,
+      :min_version,
+      :max_version,
+      :verify_callback,
+      :verify_depth,
+      :verify_mode,
+      :verify_hostname,
+    ].freeze # :nodoc:
+
+    SSL_IVNAMES = SSL_ATTRIBUTES.map { |a| "@#{a}".to_sym }.freeze # :nodoc:
+
+    # Sets or returns the path to a CA certification file in PEM format.
     attr_accessor :ca_file
 
-    # Sets path of a CA certification directory containing certifications in
-    # PEM format.
+    # Sets or returns the path of to CA directory
+    # containing certification files in PEM format.
     attr_accessor :ca_path
 
-    # Sets an OpenSSL::X509::Certificate object as client certificate.
-    # (This method is appeared in Michal Rokos's OpenSSL extension).
+    # Sets or returns the OpenSSL::X509::Certificate object
+    # to be used for client certification.
     attr_accessor :cert
 
-    # Sets the X509::Store to verify peer certificate.
+    # Sets or returns the X509::Store to be used for verifying peer certificate.
     attr_accessor :cert_store
 
-    # Sets the available ciphers.  See OpenSSL::SSL::SSLContext#ciphers=
+    # Sets or returns the available SSL ciphers.
+    # See {OpenSSL::SSL::SSLContext#ciphers=}[OpenSSL::SSL::SSL::Context#ciphers=].
     attr_accessor :ciphers
 
-    # Sets an OpenSSL::PKey::RSA or OpenSSL::PKey::DSA object.
-    # (This method is appeared in Michal Rokos's OpenSSL extension.)
+    # Sets or returns the extra X509 certificates to be added to the certificate chain.
+    # See {OpenSSL::SSL::SSLContext#add_certificate}[OpenSSL::SSL::SSL::Context#add_certificate].
+    attr_accessor :extra_chain_cert
+
+    # Sets or returns the OpenSSL::PKey::RSA or OpenSSL::PKey::DSA object.
     attr_accessor :key
 
-    # Sets the SSL timeout seconds.
+    # Sets or returns the SSL timeout seconds.
     attr_accessor :ssl_timeout
 
-    # Sets the SSL version.  See OpenSSL::SSL::SSLContext#ssl_version=
+    # Sets or returns the SSL version.
+    # See {OpenSSL::SSL::SSLContext#ssl_version=}[OpenSSL::SSL::SSL::Context#ssl_version=].
     attr_accessor :ssl_version
 
-    # Sets the verify callback for the server certification verification.
+    # Sets or returns the minimum SSL version.
+    # See {OpenSSL::SSL::SSLContext#min_version=}[OpenSSL::SSL::SSL::Context#min_version=].
+    attr_accessor :min_version
+
+    # Sets or returns the maximum SSL version.
+    # See {OpenSSL::SSL::SSLContext#max_version=}[OpenSSL::SSL::SSL::Context#max_version=].
+    attr_accessor :max_version
+
+    # Sets or returns the callback for the server certification verification.
     attr_accessor :verify_callback
 
-    # Sets the maximum depth for the certificate chain verification.
+    # Sets or returns the maximum depth for the certificate chain verification.
     attr_accessor :verify_depth
 
-    # Sets the flags for server the certification verification at beginning of
-    # SSL/TLS session.
-    #
+    # Sets or returns the flags for server the certification verification
+    # at the beginning of the SSL/TLS session.
     # OpenSSL::SSL::VERIFY_NONE or OpenSSL::SSL::VERIFY_PEER are acceptable.
     attr_accessor :verify_mode
 
-    # Returns the X.509 certificates the server presented.
+    # Sets or returns whether to verify that the server certificate is valid
+    # for the hostname.
+    # See {OpenSSL::SSL::SSLContext#verify_hostname=}[OpenSSL::SSL::SSL::Context#verify_hostname=].
+    attr_accessor :verify_hostname
+
+    # Returns the X509 certificate chain (an array of strings)
+    # for the session's socket peer,
+    # or +nil+ if none.
     def peer_cert
       if not use_ssl? or not @socket
         return nil
@@ -729,14 +1601,26 @@ module Net   #:nodoc:
       @socket.io.peer_cert
     end
 
-    # Opens a TCP connection and HTTP session.
+    # Starts an \HTTP session.
+    #
+    # Without a block, returns +self+:
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   # => #<Net::HTTP jsonplaceholder.typicode.com:80 open=false>
+    #   http.start
+    #   # => #<Net::HTTP jsonplaceholder.typicode.com:80 open=true>
+    #   http.started? # => true
+    #   http.finish
     #
-    # When this method is called with a block, it passes the Net::HTTP
-    # object to the block, and closes the TCP connection and HTTP session
-    # after the block has been executed.
+    # With a block, calls the block with +self+,
+    # finishes the session when the block exits,
+    # and returns the block's value:
     #
-    # When called with a block, it returns the return value of the
-    # block; otherwise, it returns self.
+    #   http.start do |http|
+    #     http
+    #   end
+    #   # => #<Net::HTTP jsonplaceholder.typicode.com:80 open=false>
+    #   http.started? # => false
     #
     def start  # :yield: http
       raise IOError, 'HTTP session already opened' if @started
@@ -752,6 +1636,21 @@ module Net   #:nodoc:
       self
     end
 
+    # Finishes the \HTTP session:
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.start
+    #   http.started? # => true
+    #   http.finish   # => nil
+    #   http.started? # => false
+    #
+    # Raises IOError if not in a session.
+    def finish
+      raise IOError, 'HTTP session not yet started' unless started?
+      do_finish
+    end
+
+    # :stopdoc:
     def do_start
       connect
       @started = true
@@ -759,72 +1658,150 @@ module Net   #:nodoc:
     private :do_start
 
     def connect
-      D "opening connection to #{conn_address()}..."
-      s = timeout(@open_timeout) { TCPSocket.open(conn_address(), conn_port()) }
-      D "opened"
       if use_ssl?
+        # reference early to load OpenSSL before connecting,
+        # as OpenSSL may take time to load.
+        @ssl_context = OpenSSL::SSL::SSLContext.new
+      end
+
+      if proxy? then
+        conn_addr = proxy_address
+        conn_port = proxy_port
+      else
+        conn_addr = conn_address
+        conn_port = port
+      end
+
+      debug "opening connection to #{conn_addr}:#{conn_port}..."
+      begin
+        s = timeouted_connect(conn_addr, conn_port)
+      rescue => e
+        if (defined?(IO::TimeoutError) && e.is_a?(IO::TimeoutError)) || e.is_a?(Errno::ETIMEDOUT)  # for compatibility with previous versions
+          e = Net::OpenTimeout.new(e)
+        end
+        raise e, "Failed to open TCP connection to " +
+          "#{conn_addr}:#{conn_port} (#{e.message})"
+      end
+      s.setsockopt(Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1)
+      debug "opened"
+      if use_ssl?
+        if proxy?
+          if @proxy_use_ssl
+            proxy_sock = OpenSSL::SSL::SSLSocket.new(s)
+            ssl_socket_connect(proxy_sock, @open_timeout)
+          else
+            proxy_sock = s
+          end
+          proxy_sock = BufferedIO.new(proxy_sock, read_timeout: @read_timeout,
+                                      write_timeout: @write_timeout,
+                                      continue_timeout: @continue_timeout,
+                                      debug_output: @debug_output)
+          buf = +"CONNECT #{conn_address}:#{@port} HTTP/#{HTTPVersion}\r\n" \
+            "Host: #{@address}:#{@port}\r\n"
+          if proxy_user
+            credential = ["#{proxy_user}:#{proxy_pass}"].pack('m0')
+            buf << "Proxy-Authorization: Basic #{credential}\r\n"
+          end
+          buf << "\r\n"
+          proxy_sock.write(buf)
+          HTTPResponse.read_new(proxy_sock).value
+          # assuming nothing left in buffers after successful CONNECT response
+        end
+
         ssl_parameters = Hash.new
         iv_list = instance_variables
-        SSL_ATTRIBUTES.each do |name|
-          ivname = "@#{name}".intern
-          if iv_list.include?(ivname) and
-             value = instance_variable_get(ivname)
-            ssl_parameters[name] = value
+        SSL_IVNAMES.each_with_index do |ivname, i|
+          if iv_list.include?(ivname)
+            value = instance_variable_get(ivname)
+            unless value.nil?
+              ssl_parameters[SSL_ATTRIBUTES[i]] = value
+            end
           end
         end
-        @ssl_context = OpenSSL::SSL::SSLContext.new
         @ssl_context.set_params(ssl_parameters)
+        unless @ssl_context.session_cache_mode.nil? # a dummy method on JRuby
+          @ssl_context.session_cache_mode =
+              OpenSSL::SSL::SSLContext::SESSION_CACHE_CLIENT |
+                  OpenSSL::SSL::SSLContext::SESSION_CACHE_NO_INTERNAL_STORE
+        end
+        if @ssl_context.respond_to?(:session_new_cb) # not implemented under JRuby
+          @ssl_context.session_new_cb = proc {|sock, sess| @ssl_session = sess }
+        end
+
+        # Still do the post_connection_check below even if connecting
+        # to IP address
+        verify_hostname = @ssl_context.verify_hostname
+
+        # Server Name Indication (SNI) RFC 3546/6066
+        case @address
+        when Resolv::IPv4::Regex, Resolv::IPv6::Regex
+          # don't set SNI, as IP addresses in SNI is not valid
+          # per RFC 6066, section 3.
+
+          # Avoid openssl warning
+          @ssl_context.verify_hostname = false
+        else
+          ssl_host_address = @address
+        end
+
+        debug "starting SSL for #{conn_addr}:#{conn_port}..."
         s = OpenSSL::SSL::SSLSocket.new(s, @ssl_context)
         s.sync_close = true
-      end
-      @socket = BufferedIO.new(s)
-      @socket.read_timeout = @read_timeout
-      @socket.continue_timeout = @continue_timeout
-      @socket.debug_output = @debug_output
-      if use_ssl?
-        begin
-          if proxy?
-            @socket.writeline sprintf('CONNECT %s:%s HTTP/%s',
-                                      @address, @port, HTTPVersion)
-            @socket.writeline "Host: #{@address}:#{@port}"
-            if proxy_user
-              credential = ["#{proxy_user}:#{proxy_pass}"].pack('m')
-              credential.delete!("\r\n")
-              @socket.writeline "Proxy-Authorization: Basic #{credential}"
-            end
-            @socket.writeline ''
-            HTTPResponse.read_new(@socket).value
-          end
-          # Server Name Indication (SNI) RFC 3546
-          s.hostname = @address if s.respond_to? :hostname=
-          timeout(@open_timeout) { s.connect }
-          if @ssl_context.verify_mode != OpenSSL::SSL::VERIFY_NONE
-            s.post_connection_check(@address)
-          end
-        rescue => exception
-          D "Conn close because of connect error #{exception}"
-          @socket.close if @socket and not @socket.closed?
-          raise exception
+        s.hostname = ssl_host_address if s.respond_to?(:hostname=) && ssl_host_address
+
+        if @ssl_session and
+           Process.clock_gettime(Process::CLOCK_REALTIME) < @ssl_session.time.to_f + @ssl_session.timeout
+          s.session = @ssl_session
         end
+        ssl_socket_connect(s, @open_timeout)
+        if (@ssl_context.verify_mode != OpenSSL::SSL::VERIFY_NONE) && verify_hostname
+          s.post_connection_check(@address)
+        end
+        debug "SSL established, protocol: #{s.ssl_version}, cipher: #{s.cipher[0]}"
       end
+      @socket = BufferedIO.new(s, read_timeout: @read_timeout,
+                               write_timeout: @write_timeout,
+                               continue_timeout: @continue_timeout,
+                               debug_output: @debug_output)
+      @last_communicated = nil
       on_connect
+    rescue => exception
+      if s
+        debug "Conn close because of connect error #{exception}"
+        s.close
+      end
+      raise
     end
     private :connect
 
-    def on_connect
+    tcp_socket_parameters = TCPSocket.instance_method(:initialize).parameters
+    TCP_SOCKET_NEW_HAS_OPEN_TIMEOUT = if tcp_socket_parameters != [[:rest]]
+      tcp_socket_parameters.include?([:key, :open_timeout])
+    else
+      # Use Socket.tcp to find out since there is no parameters information for TCPSocket#initialize
+      # See discussion in https://github.com/ruby/net-http/pull/224
+      Socket.method(:tcp).parameters.include?([:key, :open_timeout])
     end
-    private :on_connect
+    private_constant :TCP_SOCKET_NEW_HAS_OPEN_TIMEOUT
 
-    # Finishes the HTTP session and closes the TCP connection.
-    # Raises IOError if the session has not been started.
-    def finish
-      raise IOError, 'HTTP session not yet started' unless started?
-      do_finish
+    def timeouted_connect(conn_addr, conn_port)
+      if TCP_SOCKET_NEW_HAS_OPEN_TIMEOUT
+        TCPSocket.open(conn_addr, conn_port, @local_host, @local_port, open_timeout: @open_timeout)
+      else
+        Timeout.timeout(@open_timeout, Net::OpenTimeout) {
+          TCPSocket.open(conn_addr, conn_port, @local_host, @local_port)
+        }
+      end
     end
+    private :timeouted_connect
+
+    def on_connect
+    end
+    private :on_connect
 
     def do_finish
       @started = false
-      @socket.close if @socket and not @socket.closed?
+      @socket.close if @socket
       @socket = nil
     end
     private :do_finish
@@ -837,141 +1814,166 @@ module Net   #:nodoc:
 
     # no proxy
     @is_proxy_class = false
+    @proxy_from_env = false
     @proxy_addr = nil
     @proxy_port = nil
     @proxy_user = nil
     @proxy_pass = nil
+    @proxy_use_ssl = nil
 
-    # Creates an HTTP proxy class which behaves like Net::HTTP, but
+    # Creates an \HTTP proxy class which behaves like \Net::HTTP, but
     # performs all access via the specified proxy.
     #
-    # The arguments are the DNS name or IP address of the proxy host,
-    # the port to use to access the proxy, and a username and password
-    # if authorization is required to use the proxy.
-    #
-    # You can replace any use of the Net::HTTP class with use of the
-    # proxy class created.
-    #
-    # If +p_addr+ is nil, this method returns self (a Net::HTTP object).
-    #
-    #   # Example
-    #   proxy_class = Net::HTTP::Proxy('proxy.example.com', 8080)
-    #
-    #   proxy_class.start('www.ruby-lang.org') {|http|
-    #     # connecting proxy.foo.org:8080
-    #   }
-    #
-    # You may use them to work with authorization-enabled proxies:
-    #
-    #   proxy_host = 'your.proxy.example'
-    #   proxy_port = 8080
-    #   proxy_user = 'user'
-    #   proxy_pass = 'pass'
-    #
-    #   proxy = Net::HTTP::Proxy(proxy_host, proxy_port, proxy_user, proxy_pass)
-    #   proxy.start('www.example.com') { |http|
-    #     # always connect to your.proxy.example:8080 using specified username
-    #     # and password
-    #   }
-    #
-    # Note that net/http does not use the HTTP_PROXY environment variable.
-    # If you want to use a proxy, you must set it explicitly.
-    #
-    def HTTP.Proxy(p_addr, p_port = nil, p_user = nil, p_pass = nil)
+    # This class is obsolete.  You may pass these same parameters directly to
+    # \Net::HTTP.new.  See Net::HTTP.new for details of the arguments.
+    def HTTP.Proxy(p_addr = :ENV, p_port = nil, p_user = nil, p_pass = nil, p_use_ssl = nil) #:nodoc:
       return self unless p_addr
-      delta = ProxyDelta
-      proxyclass = Class.new(self)
-      proxyclass.module_eval {
-        include delta
-        # with proxy
+
+      Class.new(self) {
         @is_proxy_class = true
-        @proxy_address = p_addr
-        @proxy_port    = p_port || default_port()
-        @proxy_user    = p_user
-        @proxy_pass    = p_pass
+
+        if p_addr == :ENV then
+          @proxy_from_env = true
+          @proxy_address = nil
+          @proxy_port    = nil
+        else
+          @proxy_from_env = false
+          @proxy_address = p_addr
+          @proxy_port    = p_port || default_port
+        end
+
+        @proxy_user = p_user
+        @proxy_pass = p_pass
+        @proxy_use_ssl = p_use_ssl
       }
-      proxyclass
     end
 
+    # :startdoc:
+
     class << HTTP
-      # returns true if self is a class which was created by HTTP::Proxy.
+      # Returns true if self is a class which was created by HTTP::Proxy.
       def proxy_class?
-        @is_proxy_class
+        defined?(@is_proxy_class) ? @is_proxy_class : false
       end
 
-      # Address of proxy host. If Net::HTTP does not use a proxy, nil.
+      # Returns the address of the proxy host, or +nil+ if none;
+      # see Net::HTTP@Proxy+Server.
       attr_reader :proxy_address
 
-      # Port number of proxy host. If Net::HTTP does not use a proxy, nil.
+      # Returns the port number of the proxy host, or +nil+ if none;
+      # see Net::HTTP@Proxy+Server.
       attr_reader :proxy_port
 
-      # User name for accessing proxy. If Net::HTTP does not use a proxy, nil.
+      # Returns the user name for accessing the proxy, or +nil+ if none;
+      # see Net::HTTP@Proxy+Server.
       attr_reader :proxy_user
 
-      # User password for accessing proxy. If Net::HTTP does not use a proxy,
-      # nil.
+      # Returns the password for accessing the proxy, or +nil+ if none;
+      # see Net::HTTP@Proxy+Server.
       attr_reader :proxy_pass
+
+      # Use SSL when talking to the proxy. If Net::HTTP does not use a proxy, nil.
+      attr_reader :proxy_use_ssl
     end
 
-    # True if self is a HTTP proxy class.
+    # Returns +true+ if a proxy server is defined, +false+ otherwise;
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
     def proxy?
-      self.class.proxy_class?
+      !!(@proxy_from_env ? proxy_uri : @proxy_address)
+    end
+
+    # Returns +true+ if the proxy server is defined in the environment,
+    # +false+ otherwise;
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
+    def proxy_from_env?
+      @proxy_from_env
+    end
+
+    # The proxy URI determined from the environment for this connection.
+    def proxy_uri # :nodoc:
+      return if @proxy_uri == false
+      @proxy_uri ||= URI::HTTP.new(
+        "http", nil, address, port, nil, nil, nil, nil, nil
+      ).find_proxy || false
+      @proxy_uri || nil
     end
 
-    # A convenience method for accessing value of proxy_address from Net::HTTP.
+    # Returns the address of the proxy server, if defined, +nil+ otherwise;
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
     def proxy_address
-      self.class.proxy_address
+      if @proxy_from_env then
+        proxy_uri&.hostname
+      else
+        @proxy_address
+      end
     end
 
-    # A convenience method for accessing value of proxy_port from Net::HTTP.
+    # Returns the port number of the proxy server, if defined, +nil+ otherwise;
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
     def proxy_port
-      self.class.proxy_port
+      if @proxy_from_env then
+        proxy_uri&.port
+      else
+        @proxy_port
+      end
     end
 
-    # A convenience method for accessing value of proxy_user from Net::HTTP.
+    # Returns the user name of the proxy server, if defined, +nil+ otherwise;
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
     def proxy_user
-      self.class.proxy_user
+      if @proxy_from_env
+        user = proxy_uri&.user
+        unescape(user) if user
+      else
+        @proxy_user
+      end
     end
 
-    # A convenience method for accessing value of proxy_pass from Net::HTTP.
+    # Returns the password of the proxy server, if defined, +nil+ otherwise;
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
     def proxy_pass
-      self.class.proxy_pass
+      if @proxy_from_env
+        pass = proxy_uri&.password
+        unescape(pass) if pass
+      else
+        @proxy_pass
+      end
     end
 
     alias proxyaddr proxy_address   #:nodoc: obsolete
     alias proxyport proxy_port      #:nodoc: obsolete
 
     private
+    # :stopdoc:
 
-    # without proxy
+    def unescape(value)
+      require 'cgi/escape'
+      require 'cgi/util' unless defined?(CGI::EscapeExt)
+      CGI.unescape(value)
+    end
+
+    # without proxy, obsolete
 
-    def conn_address
-      address()
+    def conn_address # :nodoc:
+      @ipaddr || address()
     end
 
-    def conn_port
+    def conn_port # :nodoc:
       port()
     end
 
     def edit_path(path)
-      path
-    end
-
-    module ProxyDelta   #:nodoc: internal use only
-      private
-
-      def conn_address
-        proxy_address()
-      end
-
-      def conn_port
-        proxy_port()
-      end
-
-      def edit_path(path)
-        use_ssl? ? path : "http://#{addr_port()}#{path}"
+      if proxy?
+        if path.start_with?("ftp://") || use_ssl?
+          path
+        else
+          "http://#{addr_port}#{path}"
+        end
+      else
+        path
       end
     end
+    # :startdoc:
 
     #
     # HTTP operations
@@ -979,267 +1981,356 @@ module Net   #:nodoc:
 
     public
 
-    # Gets data from +path+ on the connected-to host.
-    # +initheader+ must be a Hash like { 'Accept' => '*/*', ... },
-    # and it defaults to an empty hash.
-    # If +initheader+ doesn't have the key 'accept-encoding', then
-    # a value of "gzip;q=1.0,deflate;q=0.6,identity;q=0.3" is used,
-    # so that gzip compression is used in preference to deflate
-    # compression, which is used in preference to no compression.
-    # Ruby doesn't have libraries to support the compress (Lempel-Ziv)
-    # compression, so that is not supported.  The intent of this is
-    # to reduce bandwidth by default.   If this routine sets up
-    # compression, then it does the decompression also, removing
-    # the header as well to prevent confusion.  Otherwise
-    # it leaves the body as it found it.
-    #
-    # This method returns a Net::HTTPResponse object.
-    #
-    # If called with a block, yields each fragment of the
-    # entity body in turn as a string as it is read from
-    # the socket.  Note that in this case, the returned response
-    # object will *not* contain a (meaningful) body.
-    #
-    # +dest+ argument is obsolete.
-    # It still works but you must not use it.
-    #
-    # This method never raises an exception.
-    #
-    #     response = http.get('/index.html')
-    #
-    #     # using block
-    #     File.open('result.txt', 'w') {|f|
-    #       http.get('/~foo/') do |str|
-    #         f.write str
-    #       end
-    #     }
-    #
-    def get(path, initheader = {}, dest = nil, &block) # :yield: +body_segment+
+    # :call-seq:
+    #    get(path, initheader = nil) {|res| ... }
+    #
+    # Sends a GET request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Get object
+    # created from string +path+ and initial headers hash +initheader+.
+    #
+    # With a block given, calls the block with the response body:
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.get('/todos/1') do |res|
+    #     p res
+    #   end # => #<Net::HTTPOK 200 OK readbody=true>
+    #
+    # Output:
+    #
+    #   "{\n  \"userId\": 1,\n  \"id\": 1,\n  \"title\": \"delectus aut autem\",\n  \"completed\": false\n}"
+    #
+    # With no block given, simply returns the response object:
+    #
+    #   http.get('/') # => #<Net::HTTPOK 200 OK readbody=true>
+    #
+    # Related:
+    #
+    # - Net::HTTP::Get: request class for \HTTP method GET.
+    # - Net::HTTP.get: sends GET request, returns response body.
+    #
+    def get(path, initheader = nil, dest = nil, &block) # :yield: +body_segment+
       res = nil
-      if HAVE_ZLIB
-        unless  initheader.keys.any?{|k| k.downcase == "accept-encoding"}
-          initheader = initheader.merge({
-            "accept-encoding" => "gzip;q=1.0,deflate;q=0.6,identity;q=0.3"
-          })
-          @compression = true
-        end
-      end
+
       request(Get.new(path, initheader)) {|r|
-        if r.key?("content-encoding") and @compression
-          @compression = nil # Clear it till next set.
-          the_body = r.read_body dest, &block
-          case r["content-encoding"]
-          when "gzip"
-            r.body= Zlib::GzipReader.new(StringIO.new(the_body), encoding: "ASCII-8BIT").read
-            r.delete("content-encoding")
-          when "deflate"
-            r.body= Zlib::Inflate.inflate(the_body);
-            r.delete("content-encoding")
-          when "identity"
-            ; # nothing needed
-          else
-            ; # Don't do anything dramatic, unless we need to later
-          end
-        else
-          r.read_body dest, &block
-        end
+        r.read_body dest, &block
         res = r
       }
       res
     end
 
-    # Gets only the header from +path+ on the connected-to host.
-    # +header+ is a Hash like { 'Accept' => '*/*', ... }.
-    #
-    # This method returns a Net::HTTPResponse object.
+    # Sends a HEAD request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
     #
-    # This method never raises an exception.
+    # The request is based on the Net::HTTP::Head object
+    # created from string +path+ and initial headers hash +initheader+:
     #
-    #     response = nil
-    #     Net::HTTP.start('some.www.server', 80) {|http|
-    #       response = http.head('/index.html')
-    #     }
-    #     p response['content-type']
+    #   res = http.head('/todos/1') # => #<Net::HTTPOK 200 OK readbody=true>
+    #   res.body                    # => nil
+    #   res.to_hash.take(3)
+    #   # =>
+    #   [["date", ["Wed, 15 Feb 2023 15:25:42 GMT"]],
+    #    ["content-type", ["application/json; charset=utf-8"]],
+    #    ["connection", ["close"]]]
     #
     def head(path, initheader = nil)
       request(Head.new(path, initheader))
     end
 
-    # Posts +data+ (must be a String) to +path+. +header+ must be a Hash
-    # like { 'Accept' => '*/*', ... }.
+    # :call-seq:
+    #    post(path, data, initheader = nil) {|res| ... }
+    #
+    # Sends a POST request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
     #
-    # This method returns a Net::HTTPResponse object.
+    # The request is based on the Net::HTTP::Post object
+    # created from string +path+, string +data+, and initial headers hash +initheader+.
     #
-    # If called with a block, yields each fragment of the
-    # entity body in turn as a string as it is read from
-    # the socket.  Note that in this case, the returned response
-    # object will *not* contain a (meaningful) body.
+    # With a block given, calls the block with the response body:
     #
-    # +dest+ argument is obsolete.
-    # It still works but you must not use it.
+    #   data = '{"userId": 1, "id": 1, "title": "delectus aut autem", "completed": false}'
+    #   http = Net::HTTP.new(hostname)
+    #   http.post('/todos', data) do |res|
+    #     p res
+    #   end # => #<Net::HTTPCreated 201 Created readbody=true>
     #
-    # This method never raises exception.
+    # Output:
     #
-    #     response = http.post('/cgi-bin/search.rb', 'query=foo')
+    #   "{\n  \"{\\\"userId\\\": 1, \\\"id\\\": 1, \\\"title\\\": \\\"delectus aut autem\\\", \\\"completed\\\": false}\": \"\",\n  \"id\": 201\n}"
     #
-    #     # using block
-    #     File.open('result.txt', 'w') {|f|
-    #       http.post('/cgi-bin/search.rb', 'query=foo') do |str|
-    #         f.write str
-    #       end
-    #     }
+    # With no block given, simply returns the response object:
     #
-    # You should set Content-Type: header field for POST.
-    # If no Content-Type: field given, this method uses
-    # "application/x-www-form-urlencoded" by default.
+    #   http.post('/todos', data) # => #<Net::HTTPCreated 201 Created readbody=true>
+    #
+    # Related:
+    #
+    # - Net::HTTP::Post: request class for \HTTP method POST.
+    # - Net::HTTP.post: sends POST request, returns response body.
     #
     def post(path, data, initheader = nil, dest = nil, &block) # :yield: +body_segment+
       send_entity(path, data, initheader, dest, Post, &block)
     end
 
-    # Sends a PATCH request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # :call-seq:
+    #    patch(path, data, initheader = nil) {|res| ... }
+    #
+    # Sends a PATCH request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Patch object
+    # created from string +path+, string +data+, and initial headers hash +initheader+.
+    #
+    # With a block given, calls the block with the response body:
+    #
+    #   data = '{"userId": 1, "id": 1, "title": "delectus aut autem", "completed": false}'
+    #   http = Net::HTTP.new(hostname)
+    #   http.patch('/todos/1', data) do |res|
+    #     p res
+    #   end # => #<Net::HTTPOK 200 OK readbody=true>
+    #
+    # Output:
+    #
+    #   "{\n  \"userId\": 1,\n  \"id\": 1,\n  \"title\": \"delectus aut autem\",\n  \"completed\": false,\n  \"{\\\"userId\\\": 1, \\\"id\\\": 1, \\\"title\\\": \\\"delectus aut autem\\\", \\\"completed\\\": false}\": \"\"\n}"
+    #
+    # With no block given, simply returns the response object:
+    #
+    #   http.patch('/todos/1', data) # => #<Net::HTTPCreated 201 Created readbody=true>
+    #
     def patch(path, data, initheader = nil, dest = nil, &block) # :yield: +body_segment+
       send_entity(path, data, initheader, dest, Patch, &block)
     end
 
-    def put(path, data, initheader = nil)   #:nodoc:
+    # Sends a PUT request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Put object
+    # created from string +path+, string +data+, and initial headers hash +initheader+.
+    #
+    #   data = '{"userId": 1, "id": 1, "title": "delectus aut autem", "completed": false}'
+    #   http = Net::HTTP.new(hostname)
+    #   http.put('/todos/1', data) # => #<Net::HTTPOK 200 OK readbody=true>
+    #
+    # Related:
+    #
+    # - Net::HTTP::Put: request class for \HTTP method PUT.
+    # - Net::HTTP.put: sends PUT request, returns response body.
+    #
+    def put(path, data, initheader = nil)
       request(Put.new(path, initheader), data)
     end
 
-    # Sends a PROPPATCH request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # Sends a PROPPATCH request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Proppatch object
+    # created from string +path+, string +body+, and initial headers hash +initheader+.
+    #
+    #   data = '{"userId": 1, "id": 1, "title": "delectus aut autem", "completed": false}'
+    #   http = Net::HTTP.new(hostname)
+    #   http.proppatch('/todos/1', data)
+    #
     def proppatch(path, body, initheader = nil)
       request(Proppatch.new(path, initheader), body)
     end
 
-    # Sends a LOCK request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # Sends a LOCK request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Lock object
+    # created from string +path+, string +body+, and initial headers hash +initheader+.
+    #
+    #   data = '{"userId": 1, "id": 1, "title": "delectus aut autem", "completed": false}'
+    #   http = Net::HTTP.new(hostname)
+    #   http.lock('/todos/1', data)
+    #
     def lock(path, body, initheader = nil)
       request(Lock.new(path, initheader), body)
     end
 
-    # Sends a UNLOCK request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # Sends an UNLOCK request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Unlock object
+    # created from string +path+, string +body+, and initial headers hash +initheader+.
+    #
+    #   data = '{"userId": 1, "id": 1, "title": "delectus aut autem", "completed": false}'
+    #   http = Net::HTTP.new(hostname)
+    #   http.unlock('/todos/1', data)
+    #
     def unlock(path, body, initheader = nil)
       request(Unlock.new(path, initheader), body)
     end
 
-    # Sends a OPTIONS request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # Sends an Options request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Options object
+    # created from string +path+ and initial headers hash +initheader+.
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.options('/')
+    #
     def options(path, initheader = nil)
       request(Options.new(path, initheader))
     end
 
-    # Sends a PROPFIND request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # Sends a PROPFIND request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Propfind object
+    # created from string +path+, string +body+, and initial headers hash +initheader+.
+    #
+    #   data = '{"userId": 1, "id": 1, "title": "delectus aut autem", "completed": false}'
+    #   http = Net::HTTP.new(hostname)
+    #   http.propfind('/todos/1', data)
+    #
     def propfind(path, body = nil, initheader = {'Depth' => '0'})
       request(Propfind.new(path, initheader), body)
     end
 
-    # Sends a DELETE request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # Sends a DELETE request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Delete object
+    # created from string +path+ and initial headers hash +initheader+.
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.delete('/todos/1')
+    #
     def delete(path, initheader = {'Depth' => 'Infinity'})
       request(Delete.new(path, initheader))
     end
 
-    # Sends a MOVE request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # Sends a MOVE request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Move object
+    # created from string +path+ and initial headers hash +initheader+.
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.move('/todos/1')
+    #
     def move(path, initheader = nil)
       request(Move.new(path, initheader))
     end
 
-    # Sends a COPY request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # Sends a COPY request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Copy object
+    # created from string +path+ and initial headers hash +initheader+.
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.copy('/todos/1')
+    #
     def copy(path, initheader = nil)
       request(Copy.new(path, initheader))
     end
 
-    # Sends a MKCOL request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # Sends a MKCOL request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Mkcol object
+    # created from string +path+, string +body+, and initial headers hash +initheader+.
+    #
+    #   data = '{"userId": 1, "id": 1, "title": "delectus aut autem", "completed": false}'
+    #   http.mkcol('/todos/1', data)
+    #   http = Net::HTTP.new(hostname)
+    #
     def mkcol(path, body = nil, initheader = nil)
       request(Mkcol.new(path, initheader), body)
     end
 
-    # Sends a TRACE request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # Sends a TRACE request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Trace object
+    # created from string +path+ and initial headers hash +initheader+.
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.trace('/todos/1')
+    #
     def trace(path, initheader = nil)
       request(Trace.new(path, initheader))
     end
 
-    # Sends a GET request to the +path+.
-    # Returns the response as a Net::HTTPResponse object.
+    # Sends a GET request to the server;
+    # forms the response into a Net::HTTPResponse object.
+    #
+    # The request is based on the Net::HTTP::Get object
+    # created from string +path+ and initial headers hash +initheader+.
     #
-    # When called with a block, passes an HTTPResponse object to the block.
-    # The body of the response will not have been read yet;
-    # the block can process it using HTTPResponse#read_body,
-    # if desired.
+    # With no block given, returns the response object:
     #
-    # Returns the response.
+    #   http = Net::HTTP.new(hostname)
+    #   http.request_get('/todos') # => #<Net::HTTPOK 200 OK readbody=true>
     #
-    # This method never raises Net::* exceptions.
+    # With a block given, calls the block with the response object
+    # and returns the response object:
     #
-    #     response = http.request_get('/index.html')
-    #     # The entity body is already read in this case.
-    #     p response['content-type']
-    #     puts response.body
+    #   http.request_get('/todos') do |res|
+    #     p res
+    #   end # => #<Net::HTTPOK 200 OK readbody=true>
     #
-    #     # Using a block
-    #     http.request_get('/index.html') {|response|
-    #       p response['content-type']
-    #       response.read_body do |str|   # read body now
-    #         print str
-    #       end
-    #     }
+    # Output:
+    #
+    #   #<Net::HTTPOK 200 OK readbody=false>
     #
     def request_get(path, initheader = nil, &block) # :yield: +response+
       request(Get.new(path, initheader), &block)
     end
 
-    # Sends a HEAD request to the +path+ and returns the response
-    # as a Net::HTTPResponse object.
-    #
-    # Returns the response.
+    # Sends a HEAD request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
     #
-    # This method never raises Net::* exceptions.
+    # The request is based on the Net::HTTP::Head object
+    # created from string +path+ and initial headers hash +initheader+.
     #
-    #     response = http.request_head('/index.html')
-    #     p response['content-type']
+    #   http = Net::HTTP.new(hostname)
+    #   http.head('/todos/1') # => #<Net::HTTPOK 200 OK readbody=true>
     #
     def request_head(path, initheader = nil, &block)
       request(Head.new(path, initheader), &block)
     end
 
-    # Sends a POST request to the +path+.
+    # Sends a POST request to the server;
+    # forms the response into a Net::HTTPResponse object.
+    #
+    # The request is based on the Net::HTTP::Post object
+    # created from string +path+, string +data+, and initial headers hash +initheader+.
     #
-    # Returns the response as a Net::HTTPResponse object.
+    # With no block given, returns the response object:
     #
-    # When called with a block, the block is passed an HTTPResponse
-    # object.  The body of that response will not have been read yet;
-    # the block can process it using HTTPResponse#read_body, if desired.
+    #   http = Net::HTTP.new(hostname)
+    #   http.post('/todos', 'xyzzy')
+    #   # => #<Net::HTTPCreated 201 Created readbody=true>
     #
-    # Returns the response.
+    # With a block given, calls the block with the response body
+    # and returns the response object:
     #
-    # This method never raises Net::* exceptions.
+    #   http.post('/todos', 'xyzzy') do |res|
+    #     p res
+    #   end # => #<Net::HTTPCreated 201 Created readbody=true>
     #
-    #     # example
-    #     response = http.request_post('/cgi-bin/nice.rb', 'datadatadata...')
-    #     p response.status
-    #     puts response.body          # body is already read in this case
+    # Output:
     #
-    #     # using block
-    #     http.request_post('/cgi-bin/nice.rb', 'datadatadata...') {|response|
-    #       p response.status
-    #       p response['content-type']
-    #       response.read_body do |str|   # read body now
-    #         print str
-    #       end
-    #     }
+    #   "{\n  \"xyzzy\": \"\",\n  \"id\": 201\n}"
     #
     def request_post(path, data, initheader = nil, &block) # :yield: +response+
       request Post.new(path, initheader), data, &block
     end
 
+    # Sends a PUT request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Put object
+    # created from string +path+, string +data+, and initial headers hash +initheader+.
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.put('/todos/1', 'xyzzy')
+    #   # => #<Net::HTTPOK 200 OK readbody=true>
+    #
     def request_put(path, data, initheader = nil, &block)   #:nodoc:
       request Put.new(path, initheader), data, &block
     end
@@ -1249,36 +2340,61 @@ module Net   #:nodoc:
     alias post2  request_post   #:nodoc: obsolete
     alias put2   request_put    #:nodoc: obsolete
 
-
-    # Sends an HTTP request to the HTTP server.
-    # Also sends a DATA string if +data+ is given.
+    # Sends an \HTTP request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
     #
-    # Returns a Net::HTTPResponse object.
+    # The request is based on the Net::HTTPRequest object
+    # created from string +path+, string +data+, and initial headers hash +header+.
+    # That object is an instance of the
+    # {subclass of Net::HTTPRequest}[rdoc-ref:Net::HTTPRequest@Request+Subclasses],
+    # that corresponds to the given uppercase string +name+,
+    # which must be
+    # an {HTTP request method}[https://en.wikipedia.org/wiki/HTTP#Request_methods]
+    # or a {WebDAV request method}[https://en.wikipedia.org/wiki/WebDAV#Implementation].
     #
-    # This method never raises Net::* exceptions.
+    # Examples:
     #
-    #    response = http.send_request('GET', '/index.html')
-    #    puts response.body
+    #   http = Net::HTTP.new(hostname)
+    #   http.send_request('GET', '/todos/1')
+    #   # => #<Net::HTTPOK 200 OK readbody=true>
+    #   http.send_request('POST', '/todos', 'xyzzy')
+    #   # => #<Net::HTTPCreated 201 Created readbody=true>
     #
     def send_request(name, path, data = nil, header = nil)
-      r = HTTPGenericRequest.new(name,(data ? true : false),true,path,header)
+      has_response_body = name != 'HEAD'
+      r = HTTPGenericRequest.new(name,(data ? true : false),has_response_body,path,header)
       request r, data
     end
 
-    # Sends an HTTPRequest object +req+ to the HTTP server.
+    # Sends the given request +req+ to the server;
+    # forms the response into a Net::HTTPResponse object.
+    #
+    # The given +req+ must be an instance of a
+    # {subclass of Net::HTTPRequest}[rdoc-ref:Net::HTTPRequest@Request+Subclasses].
+    # Argument +body+ should be given only if needed for the request.
+    #
+    # With no block given, returns the response object:
     #
-    # If +req+ is a Net::HTTP::Post or Net::HTTP::Put request containing
-    # data, the data is also sent. Providing data for a Net::HTTP::Head or
-    # Net::HTTP::Get request results in an ArgumentError.
+    #   http = Net::HTTP.new(hostname)
     #
-    # Returns an HTTPResponse object.
+    #   req = Net::HTTP::Get.new('/todos/1')
+    #   http.request(req)
+    #   # => #<Net::HTTPOK 200 OK readbody=true>
     #
-    # When called with a block, passes an HTTPResponse object to the block.
-    # The body of the response will not have been read yet;
-    # the block can process it using HTTPResponse#read_body,
-    # if desired.
+    #   req = Net::HTTP::Post.new('/todos')
+    #   http.request(req, 'xyzzy')
+    #   # => #<Net::HTTPCreated 201 Created readbody=true>
     #
-    # This method never raises Net::* exceptions.
+    # With a block given, calls the block with the response and returns the response:
+    #
+    #   req = Net::HTTP::Get.new('/todos/1')
+    #   http.request(req) do |res|
+    #     p res
+    #   end # => #<Net::HTTPOK 200 OK readbody=true>
+    #
+    # Output:
+    #
+    #   #<Net::HTTPOK 200 OK readbody=false>
     #
     def request(req, body = nil, &block)  # :yield: +response+
       unless started?
@@ -1312,45 +2428,101 @@ module Net   #:nodoc:
       res
     end
 
+    # :stopdoc:
+
+    IDEMPOTENT_METHODS_ = %w/GET HEAD PUT DELETE OPTIONS TRACE/.freeze # :nodoc:
+
     def transport_request(req)
-      begin_transport req
-      res = catch(:response) {
-        req.exec @socket, @curr_http_version, edit_path(req.path)
-        begin
-          res = HTTPResponse.read_new(@socket)
-        end while res.kind_of?(HTTPContinue)
+      count = 0
+      begin
+        begin_transport req
+        res = catch(:response) {
+          begin
+            req.exec @socket, @curr_http_version, edit_path(req.path)
+          rescue Errno::EPIPE
+            # Failure when writing full request, but we can probably
+            # still read the received response.
+          end
+
+          begin
+            res = HTTPResponse.read_new(@socket)
+            res.decode_content = req.decode_content
+            res.body_encoding = @response_body_encoding
+            res.ignore_eof = @ignore_eof
+          end while res.kind_of?(HTTPInformation)
+
+          res.uri = req.uri
+
+          res
+        }
         res.reading_body(@socket, req.response_body_permitted?) {
-          yield res if block_given?
+          if block_given?
+            count = max_retries # Don't restart in the middle of a download
+            yield res
+          end
         }
-        res
-      }
+      rescue Net::OpenTimeout
+        raise
+      rescue Net::ReadTimeout, IOError, EOFError,
+             Errno::ECONNRESET, Errno::ECONNABORTED, Errno::EPIPE, Errno::ETIMEDOUT,
+             # avoid a dependency on OpenSSL
+             defined?(OpenSSL::SSL) ? OpenSSL::SSL::SSLError : IOError,
+             Timeout::Error => exception
+        if count < max_retries && IDEMPOTENT_METHODS_.include?(req.method)
+          count += 1
+          @socket.close if @socket
+          debug "Conn close because of error #{exception}, and retry"
+          retry
+        end
+        debug "Conn close because of error #{exception}"
+        @socket.close if @socket
+        raise
+      end
+
       end_transport req, res
       res
     rescue => exception
-      D "Conn close because of error #{exception}"
-      @socket.close if @socket and not @socket.closed?
+      debug "Conn close because of error #{exception}"
+      @socket.close if @socket
       raise exception
     end
 
     def begin_transport(req)
-      connect if @socket.closed?
+      if @socket.closed?
+        connect
+      elsif @last_communicated
+        if @last_communicated + @keep_alive_timeout < Process.clock_gettime(Process::CLOCK_MONOTONIC)
+          debug 'Conn close because of keep_alive_timeout'
+          @socket.close
+          connect
+        elsif @socket.io.to_io.wait_readable(0) && @socket.eof?
+          debug "Conn close because of EOF"
+          @socket.close
+          connect
+        end
+      end
+
       if not req.response_body_permitted? and @close_on_empty_response
         req['connection'] ||= 'close'
       end
+
+      req.update_uri address, port, use_ssl?
       req['host'] ||= addr_port()
     end
 
     def end_transport(req, res)
       @curr_http_version = res.http_version
+      @last_communicated = nil
       if @socket.closed?
-        D 'Conn socket closed'
+        debug 'Conn socket closed'
       elsif not res.body and @close_on_empty_response
-        D 'Conn close'
+        debug 'Conn close'
         @socket.close
       elsif keep_alive?(req, res)
-        D 'Conn keep-alive'
+        debug 'Conn keep-alive'
+        @last_communicated = Process.clock_gettime(Process::CLOCK_MONOTONIC)
       else
-        D 'Conn close'
+        debug 'Conn close'
         @socket.close
       end
     end
@@ -1399,1427 +2571,38 @@ module Net   #:nodoc:
     private
 
     def addr_port
-      if use_ssl?
-        address() + (port == HTTP.https_default_port ? '' : ":#{port()}")
-      else
-        address() + (port == HTTP.http_default_port ? '' : ":#{port()}")
-      end
+      addr = address
+      addr = "[#{addr}]" if addr.include?(":")
+      default_port = use_ssl? ? HTTP.https_default_port : HTTP.http_default_port
+      default_port == port ? addr : "#{addr}:#{port}"
     end
 
-    def D(msg)
+    # Adds a message to debugging output
+    def debug(msg)
       return unless @debug_output
       @debug_output << msg
       @debug_output << "\n"
     end
 
+    alias_method :D, :debug
   end
 
+  # for backward compatibility until Ruby 4.0
+  # https://bugs.ruby-lang.org/issues/20900
+  # https://github.com/bblimke/webmock/pull/1081
   HTTPSession = HTTP
+  deprecate_constant :HTTPSession
+end
 
+require_relative 'http/exceptions'
 
-  # The HTTPHeader module defines methods for reading and writing
-  # HTTP headers.
-  #
-  # It is used as a mixin by other classes, to provide hash-like
-  # access to HTTP header values. Unlike raw hash access, HTTPHeader
-  # provides access via case-insensitive keys. It also provides
-  # methods for accessing commonly-used HTTP header values in more
-  # convenient formats.
-  #
-  module HTTPHeader
-
-    def initialize_http_header(initheader)
-      @header = {}
-      return unless initheader
-      initheader.each do |key, value|
-        warn "net/http: warning: duplicated HTTP header: #{key}" if key?(key) and $VERBOSE
-        @header[key.downcase] = [value.strip]
-      end
-    end
-
-    def size   #:nodoc: obsolete
-      @header.size
-    end
-
-    alias length size   #:nodoc: obsolete
-
-    # Returns the header field corresponding to the case-insensitive key.
-    # For example, a key of "Content-Type" might return "text/html"
-    def [](key)
-      a = @header[key.downcase] or return nil
-      a.join(', ')
-    end
+require_relative 'http/header'
 
-    # Sets the header field corresponding to the case-insensitive key.
-    def []=(key, val)
-      unless val
-        @header.delete key.downcase
-        return val
-      end
-      @header[key.downcase] = [val]
-    end
-
-    # [Ruby 1.8.3]
-    # Adds a value to a named header field, instead of replacing its value.
-    # Second argument +val+ must be a String.
-    # See also #[]=, #[] and #get_fields.
-    #
-    #   request.add_field 'X-My-Header', 'a'
-    #   p request['X-My-Header']              #=> "a"
-    #   p request.get_fields('X-My-Header')   #=> ["a"]
-    #   request.add_field 'X-My-Header', 'b'
-    #   p request['X-My-Header']              #=> "a, b"
-    #   p request.get_fields('X-My-Header')   #=> ["a", "b"]
-    #   request.add_field 'X-My-Header', 'c'
-    #   p request['X-My-Header']              #=> "a, b, c"
-    #   p request.get_fields('X-My-Header')   #=> ["a", "b", "c"]
-    #
-    def add_field(key, val)
-      if @header.key?(key.downcase)
-        @header[key.downcase].push val
-      else
-        @header[key.downcase] = [val]
-      end
-    end
-
-    # [Ruby 1.8.3]
-    # Returns an array of header field strings corresponding to the
-    # case-insensitive +key+.  This method allows you to get duplicated
-    # header fields without any processing.  See also #[].
-    #
-    #   p response.get_fields('Set-Cookie')
-    #     #=> ["session=al98axx; expires=Fri, 31-Dec-1999 23:58:23",
-    #          "query=rubyscript; expires=Fri, 31-Dec-1999 23:58:23"]
-    #   p response['Set-Cookie']
-    #     #=> "session=al98axx; expires=Fri, 31-Dec-1999 23:58:23, query=rubyscript; expires=Fri, 31-Dec-1999 23:58:23"
-    #
-    def get_fields(key)
-      return nil unless @header[key.downcase]
-      @header[key.downcase].dup
-    end
-
-    # Returns the header field corresponding to the case-insensitive key.
-    # Returns the default value +args+, or the result of the block, or
-    # raises an IndexError if there's no header field named +key+
-    # See Hash#fetch
-    def fetch(key, *args, &block)   #:yield: +key+
-      a = @header.fetch(key.downcase, *args, &block)
-      a.kind_of?(Array) ? a.join(', ') : a
-    end
-
-    # Iterates through the header names and values, passing in the name
-    # and value to the code block supplied.
-    #
-    # Example:
-    #
-    #     response.header.each_header {|key,value| puts "#{key} = #{value}" }
-    #
-    def each_header   #:yield: +key+, +value+
-      block_given? or return enum_for(__method__)
-      @header.each do |k,va|
-        yield k, va.join(', ')
-      end
-    end
-
-    alias each each_header
-
-    # Iterates through the header names in the header, passing
-    # each header name to the code block.
-    def each_name(&block)   #:yield: +key+
-      block_given? or return enum_for(__method__)
-      @header.each_key(&block)
-    end
-
-    alias each_key each_name
-
-    # Iterates through the header names in the header, passing
-    # capitalized header names to the code block.
-    #
-    # Note that header names are capitalized systematically;
-    # capitalization may not match that used by the remote HTTP
-    # server in its response.
-    def each_capitalized_name  #:yield: +key+
-      block_given? or return enum_for(__method__)
-      @header.each_key do |k|
-        yield capitalize(k)
-      end
-    end
-
-    # Iterates through header values, passing each value to the
-    # code block.
-    def each_value   #:yield: +value+
-      block_given? or return enum_for(__method__)
-      @header.each_value do |va|
-        yield va.join(', ')
-      end
-    end
-
-    # Removes a header field, specified by case-insensitive key.
-    def delete(key)
-      @header.delete(key.downcase)
-    end
-
-    # true if +key+ header exists.
-    def key?(key)
-      @header.key?(key.downcase)
-    end
-
-    # Returns a Hash consisting of header names and values.
-    # e.g.
-    # {"cache-control" => "private",
-    #  "content-type" => "text/html",
-    #  "date" => "Wed, 22 Jun 2005 22:11:50 GMT"}
-    def to_hash
-      @header.dup
-    end
-
-    # As for #each_header, except the keys are provided in capitalized form.
-    #
-    # Note that header names are capitalized systematically;
-    # capitalization may not match that used by the remote HTTP
-    # server in its response.
-    def each_capitalized
-      block_given? or return enum_for(__method__)
-      @header.each do |k,v|
-        yield capitalize(k), v.join(', ')
-      end
-    end
-
-    alias canonical_each each_capitalized
-
-    def capitalize(name)
-      name.split(/-/).map {|s| s.capitalize }.join('-')
-    end
-    private :capitalize
-
-    # Returns an Array of Range objects which represent the Range:
-    # HTTP header field, or +nil+ if there is no such header.
-    def range
-      return nil unless @header['range']
-      self['Range'].split(/,/).map {|spec|
-        m = /bytes\s*=\s*(\d+)?\s*-\s*(\d+)?/i.match(spec) or
-                raise HTTPHeaderSyntaxError, "wrong Range: #{spec}"
-        d1 = m[1].to_i
-        d2 = m[2].to_i
-        if    m[1] and m[2] then  d1..d2
-        elsif m[1]          then  d1..-1
-        elsif          m[2] then -d2..-1
-        else
-          raise HTTPHeaderSyntaxError, 'range is not specified'
-        end
-      }
-    end
-
-    # Sets the HTTP Range: header.
-    # Accepts either a Range object as a single argument,
-    # or a beginning index and a length from that index.
-    # Example:
-    #
-    #   req.range = (0..1023)
-    #   req.set_range 0, 1023
-    #
-    def set_range(r, e = nil)
-      unless r
-        @header.delete 'range'
-        return r
-      end
-      r = (r...r+e) if e
-      case r
-      when Numeric
-        n = r.to_i
-        rangestr = (n > 0 ? "0-#{n-1}" : "-#{-n}")
-      when Range
-        first = r.first
-        last = r.last
-        last -= 1 if r.exclude_end?
-        if last == -1
-          rangestr = (first > 0 ? "#{first}-" : "-#{-first}")
-        else
-          raise HTTPHeaderSyntaxError, 'range.first is negative' if first < 0
-          raise HTTPHeaderSyntaxError, 'range.last is negative' if last < 0
-          raise HTTPHeaderSyntaxError, 'must be .first < .last' if first > last
-          rangestr = "#{first}-#{last}"
-        end
-      else
-        raise TypeError, 'Range/Integer is required'
-      end
-      @header['range'] = ["bytes=#{rangestr}"]
-      r
-    end
-
-    alias range= set_range
-
-    # Returns an Integer object which represents the HTTP Content-Length:
-    # header field, or +nil+ if that field was not provided.
-    def content_length
-      return nil unless key?('Content-Length')
-      len = self['Content-Length'].slice(/\d+/) or
-          raise HTTPHeaderSyntaxError, 'wrong Content-Length format'
-      len.to_i
-    end
-
-    def content_length=(len)
-      unless len
-        @header.delete 'content-length'
-        return nil
-      end
-      @header['content-length'] = [len.to_i.to_s]
-    end
-
-    # Returns "true" if the "transfer-encoding" header is present and
-    # set to "chunked".  This is an HTTP/1.1 feature, allowing the
-    # the content to be sent in "chunks" without at the outset
-    # stating the entire content length.
-    def chunked?
-      return false unless @header['transfer-encoding']
-      field = self['Transfer-Encoding']
-      (/(?:\A|[^\-\w])chunked(?![\-\w])/i =~ field) ? true : false
-    end
-
-    # Returns a Range object which represents the value of the Content-Range:
-    # header field.
-    # For a partial entity body, this indicates where this fragment
-    # fits inside the full entity body, as range of byte offsets.
-    def content_range
-      return nil unless @header['content-range']
-      m = %r<bytes\s+(\d+)-(\d+)/(\d+|\*)>i.match(self['Content-Range']) or
-          raise HTTPHeaderSyntaxError, 'wrong Content-Range format'
-      m[1].to_i .. m[2].to_i
-    end
-
-    # The length of the range represented in Content-Range: header.
-    def range_length
-      r = content_range() or return nil
-      r.end - r.begin + 1
-    end
-
-    # Returns a content type string such as "text/html".
-    # This method returns nil if Content-Type: header field does not exist.
-    def content_type
-      return nil unless main_type()
-      if sub_type()
-      then "#{main_type()}/#{sub_type()}"
-      else main_type()
-      end
-    end
-
-    # Returns a content type string such as "text".
-    # This method returns nil if Content-Type: header field does not exist.
-    def main_type
-      return nil unless @header['content-type']
-      self['Content-Type'].split(';').first.to_s.split('/')[0].to_s.strip
-    end
-
-    # Returns a content type string such as "html".
-    # This method returns nil if Content-Type: header field does not exist
-    # or sub-type is not given (e.g. "Content-Type: text").
-    def sub_type
-      return nil unless @header['content-type']
-      _, sub = *self['Content-Type'].split(';').first.to_s.split('/')
-      return nil unless sub
-      sub.strip
-    end
-
-    # Any parameters specified for the content type, returned as a Hash.
-    # For example, a header of Content-Type: text/html; charset=EUC-JP
-    # would result in type_params returning {'charset' => 'EUC-JP'}
-    def type_params
-      result = {}
-      list = self['Content-Type'].to_s.split(';')
-      list.shift
-      list.each do |param|
-        k, v = *param.split('=', 2)
-        result[k.strip] = v.strip
-      end
-      result
-    end
-
-    # Sets the content type in an HTTP header.
-    # The +type+ should be a full HTTP content type, e.g. "text/html".
-    # The +params+ are an optional Hash of parameters to add after the
-    # content type, e.g. {'charset' => 'iso-8859-1'}
-    def set_content_type(type, params = {})
-      @header['content-type'] = [type + params.map{|k,v|"; #{k}=#{v}"}.join('')]
-    end
-
-    alias content_type= set_content_type
-
-    # Set header fields and a body from HTML form data.
-    # +params+ should be an Array of Arrays or
-    # a Hash containing HTML form data.
-    # Optional argument +sep+ means data record separator.
-    #
-    # Values are URL encoded as necessary and the content-type is set to
-    # application/x-www-form-urlencoded
-    #
-    # Example:
-    #    http.form_data = {"q" => "ruby", "lang" => "en"}
-    #    http.form_data = {"q" => ["ruby", "perl"], "lang" => "en"}
-    #    http.set_form_data({"q" => "ruby", "lang" => "en"}, ';')
-    #
-    def set_form_data(params, sep = '&')
-      query = URI.encode_www_form(params)
-      query.gsub!(/&/, sep) if sep != '&'
-      self.body = query
-      self.content_type = 'application/x-www-form-urlencoded'
-    end
-
-    alias form_data= set_form_data
-
-    # Set a HTML form data set.
-    # +params+ is the form data set; it is an Array of Arrays or a Hash
-    # +enctype is the type to encode the form data set.
-    # It is application/x-www-form-urlencoded or multipart/form-data.
-    # +formpot+ is an optional hash to specify the detail.
-    #
-    # boundary:: the boundary of the multipart message
-    # charset::  the charset of the message. All names and the values of
-    #            non-file fields are encoded as the charset.
-    #
-    # Each item of params is an array and contains following items:
-    # +name+::  the name of the field
-    # +value+:: the value of the field, it should be a String or a File
-    # +opt+::   an optional hash to specify additional information
-    #
-    # Each item is a file field or a normal field.
-    # If +value+ is a File object or the +opt+ have a filename key,
-    # the item is treated as a file field.
-    #
-    # If Transfer-Encoding is set as chunked, this send the request in
-    # chunked encoding. Because chunked encoding is HTTP/1.1 feature,
-    # you must confirm the server to support HTTP/1.1 before sending it.
-    #
-    # Example:
-    #    http.set_form([["q", "ruby"], ["lang", "en"]])
-    #
-    # See also RFC 2388, RFC 2616, HTML 4.01, and HTML5
-    #
-    def set_form(params, enctype='application/x-www-form-urlencoded', formopt={})
-      @body_data = params
-      @body = nil
-      @body_stream = nil
-      @form_option = formopt
-      case enctype
-      when /\Aapplication\/x-www-form-urlencoded\z/i,
-        /\Amultipart\/form-data\z/i
-        self.content_type = enctype
-      else
-        raise ArgumentError, "invalid enctype: #{enctype}"
-      end
-    end
-
-    # Set the Authorization: header for "Basic" authorization.
-    def basic_auth(account, password)
-      @header['authorization'] = [basic_encode(account, password)]
-    end
-
-    # Set Proxy-Authorization: header for "Basic" authorization.
-    def proxy_basic_auth(account, password)
-      @header['proxy-authorization'] = [basic_encode(account, password)]
-    end
-
-    def basic_encode(account, password)
-      'Basic ' + ["#{account}:#{password}"].pack('m').delete("\r\n")
-    end
-    private :basic_encode
-
-    def connection_close?
-      tokens(@header['connection']).include?('close') or
-      tokens(@header['proxy-connection']).include?('close')
-    end
-
-    def connection_keep_alive?
-      tokens(@header['connection']).include?('keep-alive') or
-      tokens(@header['proxy-connection']).include?('keep-alive')
-    end
-
-    def tokens(vals)
-      return [] unless vals
-      vals.map {|v| v.split(',') }.flatten\
-          .reject {|str| str.strip.empty? }\
-          .map {|tok| tok.strip.downcase }
-    end
-    private :tokens
-
-  end
-
-
-  # HTTPGenericRequest is the parent of the HTTPRequest class.
-  # Do not use this directly; use a subclass of HTTPRequest.
-  #
-  # Mixes in the HTTPHeader module to provide easier access to HTTP headers.
-  #
-  class HTTPGenericRequest
-
-    include HTTPHeader
-
-    def initialize(m, reqbody, resbody, path, initheader = nil)
-      @method = m
-      @request_has_body = reqbody
-      @response_has_body = resbody
-      raise ArgumentError, "no HTTP request path given" unless path
-      raise ArgumentError, "HTTP request path is empty" if path.empty?
-      @path = path
-      initialize_http_header initheader
-      self['Accept'] ||= '*/*'
-      self['User-Agent'] ||= 'Ruby'
-      @body = nil
-      @body_stream = nil
-      @body_data = nil
-    end
-
-    attr_reader :method
-    attr_reader :path
-
-    def inspect
-      "\#<#{self.class} #{@method}>"
-    end
-
-    def request_body_permitted?
-      @request_has_body
-    end
-
-    def response_body_permitted?
-      @response_has_body
-    end
-
-    def body_exist?
-      warn "Net::HTTPRequest#body_exist? is obsolete; use response_body_permitted?" if $VERBOSE
-      response_body_permitted?
-    end
-
-    attr_reader :body
-
-    def body=(str)
-      @body = str
-      @body_stream = nil
-      @body_data = nil
-      str
-    end
-
-    attr_reader :body_stream
-
-    def body_stream=(input)
-      @body = nil
-      @body_stream = input
-      @body_data = nil
-      input
-    end
-
-    def set_body_internal(str)   #:nodoc: internal use only
-      raise ArgumentError, "both of body argument and HTTPRequest#body set" if str and (@body or @body_stream)
-      self.body = str if str
-    end
-
-    #
-    # write
-    #
-
-    def exec(sock, ver, path)   #:nodoc: internal use only
-      if @body
-        send_request_with_body sock, ver, path, @body
-      elsif @body_stream
-        send_request_with_body_stream sock, ver, path, @body_stream
-      elsif @body_data
-        send_request_with_body_data sock, ver, path, @body_data
-      else
-        write_header sock, ver, path
-      end
-    end
-
-    private
-
-    def send_request_with_body(sock, ver, path, body)
-      self.content_length = body.bytesize
-      delete 'Transfer-Encoding'
-      supply_default_content_type
-      write_header sock, ver, path
-      wait_for_continue sock, ver if sock.continue_timeout
-      sock.write body
-    end
-
-    def send_request_with_body_stream(sock, ver, path, f)
-      unless content_length() or chunked?
-        raise ArgumentError,
-            "Content-Length not given and Transfer-Encoding is not `chunked'"
-      end
-      supply_default_content_type
-      write_header sock, ver, path
-      wait_for_continue sock, ver if sock.continue_timeout
-      if chunked?
-        while s = f.read(1024)
-          sock.write(sprintf("%x\r\n", s.bytesize) << s << "\r\n")
-        end
-        sock.write "0\r\n\r\n"
-      else
-        while s = f.read(1024)
-          sock.write s
-        end
-      end
-    end
-
-    def send_request_with_body_data(sock, ver, path, params)
-      if /\Amultipart\/form-data\z/i !~ self.content_type
-        self.content_type = 'application/x-www-form-urlencoded'
-        return send_request_with_body(sock, ver, path, URI.encode_www_form(params))
-      end
-
-      opt = @form_option.dup
-      require 'securerandom' unless defined?(SecureRandom)
-      opt[:boundary] ||= SecureRandom.urlsafe_base64(40)
-      self.set_content_type(self.content_type, boundary: opt[:boundary])
-      if chunked?
-        write_header sock, ver, path
-        encode_multipart_form_data(sock, params, opt)
-      else
-        require 'tempfile'
-        file = Tempfile.new('multipart')
-        file.binmode
-        encode_multipart_form_data(file, params, opt)
-        file.rewind
-        self.content_length = file.size
-        write_header sock, ver, path
-        IO.copy_stream(file, sock)
-      end
-    end
-
-    def encode_multipart_form_data(out, params, opt)
-      charset = opt[:charset]
-      boundary = opt[:boundary]
-      require 'securerandom' unless defined?(SecureRandom)
-      boundary ||= SecureRandom.urlsafe_base64(40)
-      chunked_p = chunked?
-
-      buf = ''
-      params.each do |key, value, h={}|
-        key = quote_string(key, charset)
-        filename =
-          h.key?(:filename) ? h[:filename] :
-          value.respond_to?(:to_path) ? File.basename(value.to_path) :
-          nil
-
-        buf << "--#{boundary}\r\n"
-        if filename
-          filename = quote_string(filename, charset)
-          type = h[:content_type] || 'application/octet-stream'
-          buf << "Content-Disposition: form-data; " \
-            "name=\"#{key}\"; filename=\"#{filename}\"\r\n" \
-            "Content-Type: #{type}\r\n\r\n"
-          if !out.respond_to?(:write) || !value.respond_to?(:read)
-            # if +out+ is not an IO or +value+ is not an IO
-            buf << (value.respond_to?(:read) ? value.read : value)
-          elsif value.respond_to?(:size) && chunked_p
-            # if +out+ is an IO and +value+ is a File, use IO.copy_stream
-            flush_buffer(out, buf, chunked_p)
-            out << "%x\r\n" % value.size if chunked_p
-            IO.copy_stream(value, out)
-            out << "\r\n" if chunked_p
-          else
-            # +out+ is an IO, and +value+ is not a File but an IO
-            flush_buffer(out, buf, chunked_p)
-            1 while flush_buffer(out, value.read(4096), chunked_p)
-          end
-        else
-          # non-file field:
-          #   HTML5 says, "The parts of the generated multipart/form-data
-          #   resource that correspond to non-file fields must not have a
-          #   Content-Type header specified."
-          buf << "Content-Disposition: form-data; name=\"#{key}\"\r\n\r\n"
-          buf << (value.respond_to?(:read) ? value.read : value)
-        end
-        buf << "\r\n"
-      end
-      buf << "--#{boundary}--\r\n"
-      flush_buffer(out, buf, chunked_p)
-      out << "0\r\n\r\n" if chunked_p
-    end
-
-    def quote_string(str, charset)
-      str = str.encode(charset, fallback:->(c){'&#%d;'%c.encode("UTF-8").ord}) if charset
-      str = str.gsub(/[\\"]/, '\\\\\&')
-    end
-
-    def flush_buffer(out, buf, chunked_p)
-      return unless buf
-      out << "%x\r\n"%buf.bytesize if chunked_p
-      out << buf
-      out << "\r\n" if chunked_p
-      buf.clear
-    end
-
-    def supply_default_content_type
-      return if content_type()
-      warn 'net/http: warning: Content-Type did not set; using application/x-www-form-urlencoded' if $VERBOSE
-      set_content_type 'application/x-www-form-urlencoded'
-    end
-
-    ##
-    # Waits up to the continue timeout for a response from the server provided
-    # we're speaking HTTP 1.1 and are expecting a 100-continue response.
-
-    def wait_for_continue(sock, ver)
-      if ver >= '1.1' and @header['expect'] and
-          @header['expect'].include?('100-continue')
-        if IO.select([sock.io], nil, nil, sock.continue_timeout)
-          res = HTTPResponse.read_new(sock)
-          unless res.kind_of?(Net::HTTPContinue)
-            throw :response, res
-          end
-        end
-      end
-    end
-
-    def write_header(sock, ver, path)
-      buf = "#{@method} #{path} HTTP/#{ver}\r\n"
-      each_capitalized do |k,v|
-        buf << "#{k}: #{v}\r\n"
-      end
-      buf << "\r\n"
-      sock.write buf
-    end
-
-  end
-
-
-  #
-  # HTTP request class.
-  # This class wraps together the request header and the request path.
-  # You cannot use this class directly. Instead, you should use one of its
-  # subclasses: Net::HTTP::Get, Net::HTTP::Post, Net::HTTP::Head.
-  #
-  class HTTPRequest < HTTPGenericRequest
-
-    # Creates HTTP request object.
-    def initialize(path, initheader = nil)
-      super self.class::METHOD,
-            self.class::REQUEST_HAS_BODY,
-            self.class::RESPONSE_HAS_BODY,
-            path, initheader
-    end
-  end
-
-
-  class HTTP   # reopen
-    #
-    # HTTP/1.1 methods --- RFC2616
-    #
-
-    # See Net::HTTPGenericRequest for attributes and methods.
-    # See Net::HTTP for usage examples.
-    class Get < HTTPRequest
-      METHOD = 'GET'
-      REQUEST_HAS_BODY  = false
-      RESPONSE_HAS_BODY = true
-    end
-
-    # See Net::HTTPGenericRequest for attributes and methods.
-    # See Net::HTTP for usage examples.
-    class Head < HTTPRequest
-      METHOD = 'HEAD'
-      REQUEST_HAS_BODY = false
-      RESPONSE_HAS_BODY = false
-    end
-
-    # See Net::HTTPGenericRequest for attributes and methods.
-    # See Net::HTTP for usage examples.
-    class Post < HTTPRequest
-      METHOD = 'POST'
-      REQUEST_HAS_BODY = true
-      RESPONSE_HAS_BODY = true
-    end
-
-    # See Net::HTTPGenericRequest for attributes and methods.
-    # See Net::HTTP for usage examples.
-    class Put < HTTPRequest
-      METHOD = 'PUT'
-      REQUEST_HAS_BODY = true
-      RESPONSE_HAS_BODY = true
-    end
-
-    # See Net::HTTPGenericRequest for attributes and methods.
-    # See Net::HTTP for usage examples.
-    class Delete < HTTPRequest
-      METHOD = 'DELETE'
-      REQUEST_HAS_BODY = false
-      RESPONSE_HAS_BODY = true
-    end
-
-    # See Net::HTTPGenericRequest for attributes and methods.
-    class Options < HTTPRequest
-      METHOD = 'OPTIONS'
-      REQUEST_HAS_BODY = false
-      RESPONSE_HAS_BODY = false
-    end
-
-    # See Net::HTTPGenericRequest for attributes and methods.
-    class Trace < HTTPRequest
-      METHOD = 'TRACE'
-      REQUEST_HAS_BODY = false
-      RESPONSE_HAS_BODY = true
-    end
-
-    #
-    # PATCH method --- RFC5789
-    #
-
-    # See Net::HTTPGenericRequest for attributes and methods.
-    class Patch < HTTPRequest
-      METHOD = 'PATCH'
-      REQUEST_HAS_BODY = true
-      RESPONSE_HAS_BODY = true
-    end
-
-    #
-    # WebDAV methods --- RFC2518
-    #
-
-    # See Net::HTTPGenericRequest for attributes and methods.
-    class Propfind < HTTPRequest
-      METHOD = 'PROPFIND'
-      REQUEST_HAS_BODY = true
-      RESPONSE_HAS_BODY = true
-    end
-
-    # See Net::HTTPGenericRequest for attributes and methods.
-    class Proppatch < HTTPRequest
-      METHOD = 'PROPPATCH'
-      REQUEST_HAS_BODY = true
-      RESPONSE_HAS_BODY = true
-    end
-
-    # See Net::HTTPGenericRequest for attributes and methods.
-    class Mkcol < HTTPRequest
-      METHOD = 'MKCOL'
-      REQUEST_HAS_BODY = true
-      RESPONSE_HAS_BODY = true
-    end
-
-    # See Net::HTTPGenericRequest for attributes and methods.
-    class Copy < HTTPRequest
-      METHOD = 'COPY'
-      REQUEST_HAS_BODY = false
-      RESPONSE_HAS_BODY = true
-    end
-
-    # See Net::HTTPGenericRequest for attributes and methods.
-    class Move < HTTPRequest
-      METHOD = 'MOVE'
-      REQUEST_HAS_BODY = false
-      RESPONSE_HAS_BODY = true
-    end
-
-    # See Net::HTTPGenericRequest for attributes and methods.
-    class Lock < HTTPRequest
-      METHOD = 'LOCK'
-      REQUEST_HAS_BODY = true
-      RESPONSE_HAS_BODY = true
-    end
-
-    # See Net::HTTPGenericRequest for attributes and methods.
-    class Unlock < HTTPRequest
-      METHOD = 'UNLOCK'
-      REQUEST_HAS_BODY = true
-      RESPONSE_HAS_BODY = true
-    end
-  end
-
-
-  ###
-  ### Response
-  ###
-
-  # HTTP exception class.
-  # You cannot use HTTPExceptions directly; instead, you must use
-  # its subclasses.
-  module HTTPExceptions
-    def initialize(msg, res)   #:nodoc:
-      super msg
-      @response = res
-    end
-    attr_reader :response
-    alias data response    #:nodoc: obsolete
-  end
-  class HTTPError < ProtocolError
-    include HTTPExceptions
-  end
-  class HTTPRetriableError < ProtoRetriableError
-    include HTTPExceptions
-  end
-  class HTTPServerException < ProtoServerError
-    # We cannot use the name "HTTPServerError", it is the name of the response.
-    include HTTPExceptions
-  end
-  class HTTPFatalError < ProtoFatalError
-    include HTTPExceptions
-  end
-
-
-  # HTTP response class.
-  #
-  # This class wraps together the response header and the response body (the
-  # entity requested).
-  #
-  # It mixes in the HTTPHeader module, which provides access to response
-  # header values both via hash-like methods and via individual readers.
-  #
-  # Note that each possible HTTP response code defines its own
-  # HTTPResponse subclass.  These are listed below.
-  #
-  # All classes are
-  # defined under the Net module. Indentation indicates inheritance.
-  #
-  #   xxx        HTTPResponse
-  #
-  #     1xx        HTTPInformation
-  #       100        HTTPContinue
-  #       101        HTTPSwitchProtocol
-  #
-  #     2xx        HTTPSuccess
-  #       200        HTTPOK
-  #       201        HTTPCreated
-  #       202        HTTPAccepted
-  #       203        HTTPNonAuthoritativeInformation
-  #       204        HTTPNoContent
-  #       205        HTTPResetContent
-  #       206        HTTPPartialContent
-  #
-  #     3xx        HTTPRedirection
-  #       300        HTTPMultipleChoice
-  #       301        HTTPMovedPermanently
-  #       302        HTTPFound
-  #       303        HTTPSeeOther
-  #       304        HTTPNotModified
-  #       305        HTTPUseProxy
-  #       307        HTTPTemporaryRedirect
-  #
-  #     4xx        HTTPClientError
-  #       400        HTTPBadRequest
-  #       401        HTTPUnauthorized
-  #       402        HTTPPaymentRequired
-  #       403        HTTPForbidden
-  #       404        HTTPNotFound
-  #       405        HTTPMethodNotAllowed
-  #       406        HTTPNotAcceptable
-  #       407        HTTPProxyAuthenticationRequired
-  #       408        HTTPRequestTimeOut
-  #       409        HTTPConflict
-  #       410        HTTPGone
-  #       411        HTTPLengthRequired
-  #       412        HTTPPreconditionFailed
-  #       413        HTTPRequestEntityTooLarge
-  #       414        HTTPRequestURITooLong
-  #       415        HTTPUnsupportedMediaType
-  #       416        HTTPRequestedRangeNotSatisfiable
-  #       417        HTTPExpectationFailed
-  #
-  #     5xx        HTTPServerError
-  #       500        HTTPInternalServerError
-  #       501        HTTPNotImplemented
-  #       502        HTTPBadGateway
-  #       503        HTTPServiceUnavailable
-  #       504        HTTPGatewayTimeOut
-  #       505        HTTPVersionNotSupported
-  #
-  #     xxx        HTTPUnknownResponse
-  #
-  class HTTPResponse
-    # true if the response has a body.
-    def HTTPResponse.body_permitted?
-      self::HAS_BODY
-    end
-
-    def HTTPResponse.exception_type   # :nodoc: internal use only
-      self::EXCEPTION_TYPE
-    end
-  end   # reopened after
-
-  # :stopdoc:
-
-  class HTTPUnknownResponse < HTTPResponse
-    HAS_BODY = true
-    EXCEPTION_TYPE = HTTPError
-  end
-  class HTTPInformation < HTTPResponse           # 1xx
-    HAS_BODY = false
-    EXCEPTION_TYPE = HTTPError
-  end
-  class HTTPSuccess < HTTPResponse               # 2xx
-    HAS_BODY = true
-    EXCEPTION_TYPE = HTTPError
-  end
-  class HTTPRedirection < HTTPResponse           # 3xx
-    HAS_BODY = true
-    EXCEPTION_TYPE = HTTPRetriableError
-  end
-  class HTTPClientError < HTTPResponse           # 4xx
-    HAS_BODY = true
-    EXCEPTION_TYPE = HTTPServerException   # for backward compatibility
-  end
-  class HTTPServerError < HTTPResponse           # 5xx
-    HAS_BODY = true
-    EXCEPTION_TYPE = HTTPFatalError    # for backward compatibility
-  end
-
-  class HTTPContinue < HTTPInformation           # 100
-    HAS_BODY = false
-  end
-  class HTTPSwitchProtocol < HTTPInformation     # 101
-    HAS_BODY = false
-  end
-
-  class HTTPOK < HTTPSuccess                            # 200
-    HAS_BODY = true
-  end
-  class HTTPCreated < HTTPSuccess                       # 201
-    HAS_BODY = true
-  end
-  class HTTPAccepted < HTTPSuccess                      # 202
-    HAS_BODY = true
-  end
-  class HTTPNonAuthoritativeInformation < HTTPSuccess   # 203
-    HAS_BODY = true
-  end
-  class HTTPNoContent < HTTPSuccess                     # 204
-    HAS_BODY = false
-  end
-  class HTTPResetContent < HTTPSuccess                  # 205
-    HAS_BODY = false
-  end
-  class HTTPPartialContent < HTTPSuccess                # 206
-    HAS_BODY = true
-  end
-
-  class HTTPMultipleChoice < HTTPRedirection     # 300
-    HAS_BODY = true
-  end
-  class HTTPMovedPermanently < HTTPRedirection   # 301
-    HAS_BODY = true
-  end
-  class HTTPFound < HTTPRedirection              # 302
-    HAS_BODY = true
-  end
-  HTTPMovedTemporarily = HTTPFound
-  class HTTPSeeOther < HTTPRedirection           # 303
-    HAS_BODY = true
-  end
-  class HTTPNotModified < HTTPRedirection        # 304
-    HAS_BODY = false
-  end
-  class HTTPUseProxy < HTTPRedirection           # 305
-    HAS_BODY = false
-  end
-  # 306 unused
-  class HTTPTemporaryRedirect < HTTPRedirection  # 307
-    HAS_BODY = true
-  end
-
-  class HTTPBadRequest < HTTPClientError                    # 400
-    HAS_BODY = true
-  end
-  class HTTPUnauthorized < HTTPClientError                  # 401
-    HAS_BODY = true
-  end
-  class HTTPPaymentRequired < HTTPClientError               # 402
-    HAS_BODY = true
-  end
-  class HTTPForbidden < HTTPClientError                     # 403
-    HAS_BODY = true
-  end
-  class HTTPNotFound < HTTPClientError                      # 404
-    HAS_BODY = true
-  end
-  class HTTPMethodNotAllowed < HTTPClientError              # 405
-    HAS_BODY = true
-  end
-  class HTTPNotAcceptable < HTTPClientError                 # 406
-    HAS_BODY = true
-  end
-  class HTTPProxyAuthenticationRequired < HTTPClientError   # 407
-    HAS_BODY = true
-  end
-  class HTTPRequestTimeOut < HTTPClientError                # 408
-    HAS_BODY = true
-  end
-  class HTTPConflict < HTTPClientError                      # 409
-    HAS_BODY = true
-  end
-  class HTTPGone < HTTPClientError                          # 410
-    HAS_BODY = true
-  end
-  class HTTPLengthRequired < HTTPClientError                # 411
-    HAS_BODY = true
-  end
-  class HTTPPreconditionFailed < HTTPClientError            # 412
-    HAS_BODY = true
-  end
-  class HTTPRequestEntityTooLarge < HTTPClientError         # 413
-    HAS_BODY = true
-  end
-  class HTTPRequestURITooLong < HTTPClientError             # 414
-    HAS_BODY = true
-  end
-  HTTPRequestURITooLarge = HTTPRequestURITooLong
-  class HTTPUnsupportedMediaType < HTTPClientError          # 415
-    HAS_BODY = true
-  end
-  class HTTPRequestedRangeNotSatisfiable < HTTPClientError  # 416
-    HAS_BODY = true
-  end
-  class HTTPExpectationFailed < HTTPClientError             # 417
-    HAS_BODY = true
-  end
-
-  class HTTPInternalServerError < HTTPServerError   # 500
-    HAS_BODY = true
-  end
-  class HTTPNotImplemented < HTTPServerError        # 501
-    HAS_BODY = true
-  end
-  class HTTPBadGateway < HTTPServerError            # 502
-    HAS_BODY = true
-  end
-  class HTTPServiceUnavailable < HTTPServerError    # 503
-    HAS_BODY = true
-  end
-  class HTTPGatewayTimeOut < HTTPServerError        # 504
-    HAS_BODY = true
-  end
-  class HTTPVersionNotSupported < HTTPServerError   # 505
-    HAS_BODY = true
-  end
-
-  # :startdoc:
-
-
-  class HTTPResponse   # reopen
-
-    CODE_CLASS_TO_OBJ = {
-      '1' => HTTPInformation,
-      '2' => HTTPSuccess,
-      '3' => HTTPRedirection,
-      '4' => HTTPClientError,
-      '5' => HTTPServerError
-    }
-    CODE_TO_OBJ = {
-      '100' => HTTPContinue,
-      '101' => HTTPSwitchProtocol,
-
-      '200' => HTTPOK,
-      '201' => HTTPCreated,
-      '202' => HTTPAccepted,
-      '203' => HTTPNonAuthoritativeInformation,
-      '204' => HTTPNoContent,
-      '205' => HTTPResetContent,
-      '206' => HTTPPartialContent,
-
-      '300' => HTTPMultipleChoice,
-      '301' => HTTPMovedPermanently,
-      '302' => HTTPFound,
-      '303' => HTTPSeeOther,
-      '304' => HTTPNotModified,
-      '305' => HTTPUseProxy,
-      '307' => HTTPTemporaryRedirect,
-
-      '400' => HTTPBadRequest,
-      '401' => HTTPUnauthorized,
-      '402' => HTTPPaymentRequired,
-      '403' => HTTPForbidden,
-      '404' => HTTPNotFound,
-      '405' => HTTPMethodNotAllowed,
-      '406' => HTTPNotAcceptable,
-      '407' => HTTPProxyAuthenticationRequired,
-      '408' => HTTPRequestTimeOut,
-      '409' => HTTPConflict,
-      '410' => HTTPGone,
-      '411' => HTTPLengthRequired,
-      '412' => HTTPPreconditionFailed,
-      '413' => HTTPRequestEntityTooLarge,
-      '414' => HTTPRequestURITooLong,
-      '415' => HTTPUnsupportedMediaType,
-      '416' => HTTPRequestedRangeNotSatisfiable,
-      '417' => HTTPExpectationFailed,
-
-      '500' => HTTPInternalServerError,
-      '501' => HTTPNotImplemented,
-      '502' => HTTPBadGateway,
-      '503' => HTTPServiceUnavailable,
-      '504' => HTTPGatewayTimeOut,
-      '505' => HTTPVersionNotSupported
-    }
-
-    class << HTTPResponse
-      def read_new(sock)   #:nodoc: internal use only
-        httpv, code, msg = read_status_line(sock)
-        res = response_class(code).new(httpv, code, msg)
-        each_response_header(sock) do |k,v|
-          res.add_field k, v
-        end
-        res
-      end
-
-      private
-
-      def read_status_line(sock)
-        str = sock.readline
-        m = /\AHTTP(?:\/(\d+\.\d+))?\s+(\d\d\d)\s*(.*)\z/in.match(str) or
-          raise HTTPBadResponse, "wrong status line: #{str.dump}"
-        m.captures
-      end
-
-      def response_class(code)
-        CODE_TO_OBJ[code] or
-        CODE_CLASS_TO_OBJ[code[0,1]] or
-        HTTPUnknownResponse
-      end
-
-      def each_response_header(sock)
-        key = value = nil
-        while true
-          line = sock.readuntil("\n", true).sub(/\s+\z/, '')
-          break if line.empty?
-          if line[0] == ?\s or line[0] == ?\t and value
-            value << ' ' unless value.empty?
-            value << line.strip
-          else
-            yield key, value if key
-            key, value = line.strip.split(/\s*:\s*/, 2)
-            raise HTTPBadResponse, 'wrong header line format' if value.nil?
-          end
-        end
-        yield key, value if key
-      end
-    end
-
-    # next is to fix bug in RDoc, where the private inside class << self
-    # spills out.
-    public
-
-    include HTTPHeader
-
-    def initialize(httpv, code, msg)   #:nodoc: internal use only
-      @http_version = httpv
-      @code         = code
-      @message      = msg
-      initialize_http_header nil
-      @body = nil
-      @read = false
-    end
-
-    # The HTTP version supported by the server.
-    attr_reader :http_version
-
-    # The HTTP result code string. For example, '302'.  You can also
-    # determine the response type by examining which response subclass
-    # the response object is an instance of.
-    attr_reader :code
-
-    # The HTTP result message sent by the server. For example, 'Not Found'.
-    attr_reader :message
-    alias msg message   # :nodoc: obsolete
-
-    def inspect
-      "#<#{self.class} #{@code} #{@message} readbody=#{@read}>"
-    end
-
-    #
-    # response <-> exception relationship
-    #
-
-    def code_type   #:nodoc:
-      self.class
-    end
-
-    def error!   #:nodoc:
-      raise error_type().new(@code + ' ' + @message.dump, self)
-    end
-
-    def error_type   #:nodoc:
-      self.class::EXCEPTION_TYPE
-    end
-
-    # Raises an HTTP error if the response is not 2xx (success).
-    def value
-      error! unless self.kind_of?(HTTPSuccess)
-    end
-
-    #
-    # header (for backward compatibility only; DO NOT USE)
-    #
-
-    def response   #:nodoc:
-      warn "#{caller(1)[0]}: warning: HTTPResponse#response is obsolete" if $VERBOSE
-      self
-    end
-
-    def header   #:nodoc:
-      warn "#{caller(1)[0]}: warning: HTTPResponse#header is obsolete" if $VERBOSE
-      self
-    end
-
-    def read_header   #:nodoc:
-      warn "#{caller(1)[0]}: warning: HTTPResponse#read_header is obsolete" if $VERBOSE
-      self
-    end
-
-    #
-    # body
-    #
-
-    def reading_body(sock, reqmethodallowbody)  #:nodoc: internal use only
-      @socket = sock
-      @body_exist = reqmethodallowbody && self.class.body_permitted?
-      begin
-        yield
-        self.body   # ensure to read body
-      ensure
-        @socket = nil
-      end
-    end
-
-    # Gets the entity body returned by the remote HTTP server.
-    #
-    # If a block is given, the body is passed to the block, and
-    # the body is provided in fragments, as it is read in from the socket.
-    #
-    # Calling this method a second or subsequent time for the same
-    # HTTPResponse object will return the value already read.
-    #
-    #   http.request_get('/index.html') {|res|
-    #     puts res.read_body
-    #   }
-    #
-    #   http.request_get('/index.html') {|res|
-    #     p res.read_body.object_id   # 538149362
-    #     p res.read_body.object_id   # 538149362
-    #   }
-    #
-    #   # using iterator
-    #   http.request_get('/index.html') {|res|
-    #     res.read_body do |segment|
-    #       print segment
-    #     end
-    #   }
-    #
-    def read_body(dest = nil, &block)
-      if @read
-        raise IOError, "#{self.class}\#read_body called twice" if dest or block
-        return @body
-      end
-      to = procdest(dest, block)
-      stream_check
-      if @body_exist
-        read_body_0 to
-        @body = to
-      else
-        @body = nil
-      end
-      @read = true
-
-      @body
-    end
-
-    # Returns the full entity body.
-    #
-    # Calling this method a second or subsequent time will return the
-    # string already read.
-    #
-    #   http.request_get('/index.html') {|res|
-    #     puts res.body
-    #   }
-    #
-    #   http.request_get('/index.html') {|res|
-    #     p res.body.object_id   # 538149362
-    #     p res.body.object_id   # 538149362
-    #   }
-    #
-    def body
-      read_body()
-    end
-
-    # Because it may be necessary to modify the body, Eg, decompression
-    # this method facilitates that.
-    def body=(value)
-      @body = value
-    end
-
-    alias entity body   #:nodoc: obsolete
-
-    private
-
-    def read_body_0(dest)
-      if chunked?
-        read_chunked dest
-        return
-      end
-      clen = content_length()
-      if clen
-        @socket.read clen, dest, true   # ignore EOF
-        return
-      end
-      clen = range_length()
-      if clen
-        @socket.read clen, dest
-        return
-      end
-      @socket.read_all dest
-    end
-
-    def read_chunked(dest)
-      len = nil
-      total = 0
-      while true
-        line = @socket.readline
-        hexlen = line.slice(/[0-9a-fA-F]+/) or
-            raise HTTPBadResponse, "wrong chunk size line: #{line}"
-        len = hexlen.hex
-        break if len == 0
-        begin
-          @socket.read len, dest
-        ensure
-          total += len
-          @socket.read 2   # \r\n
-        end
-      end
-      until @socket.readline.empty?
-        # none
-      end
-    end
-
-    def stream_check
-      raise IOError, 'attempt to read body out of block' if @socket.closed?
-    end
-
-    def procdest(dest, block)
-      raise ArgumentError, 'both arg and block given for HTTP method' \
-          if dest and block
-      if block
-        ReadAdapter.new(block)
-      else
-        dest || ''
-      end
-    end
-
-  end
-
-
-  # :enddoc:
-
-  #--
-  # for backward compatibility
-  class HTTP
-    ProxyMod = ProxyDelta
-  end
-  module NetPrivate
-    HTTPRequest = ::Net::HTTPRequest
-  end
+require_relative 'http/generic_request'
+require_relative 'http/request'
+require_relative 'http/requests'
 
-  HTTPInformationCode = HTTPInformation
-  HTTPSuccessCode     = HTTPSuccess
-  HTTPRedirectionCode = HTTPRedirection
-  HTTPRetriableCode   = HTTPRedirection
-  HTTPClientErrorCode = HTTPClientError
-  HTTPFatalErrorCode  = HTTPClientError
-  HTTPServerErrorCode = HTTPServerError
-  HTTPResponceReceiver = HTTPResponse
+require_relative 'http/response'
+require_relative 'http/responses'
 
-end   # module Net
+require_relative 'http/proxy_delta'
diff --git a/lib/net/http/exceptions.rb b/lib/net/http/exceptions.rb
new file mode 100644
index 0000000000..4342cfc0ef
--- /dev/null
+++ b/lib/net/http/exceptions.rb
@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+module Net
+  # Net::HTTP exception class.
+  # You cannot use Net::HTTPExceptions directly; instead, you must use
+  # its subclasses.
+  module HTTPExceptions # :nodoc:
+    def initialize(msg, res)   #:nodoc:
+      super msg
+      @response = res
+    end
+    attr_reader :response
+    alias data response    #:nodoc: obsolete
+  end
+
+  # :stopdoc:
+  class HTTPError < ProtocolError
+    include HTTPExceptions
+  end
+
+  class HTTPRetriableError < ProtoRetriableError
+    include HTTPExceptions
+  end
+
+  class HTTPClientException < ProtoServerError
+    include HTTPExceptions
+  end
+
+  class HTTPFatalError < ProtoFatalError
+    include HTTPExceptions
+  end
+
+  # We cannot use the name "HTTPServerError", it is the name of the response.
+  HTTPServerException = HTTPClientException # :nodoc:
+  deprecate_constant(:HTTPServerException)
+end
diff --git a/lib/net/http/generic_request.rb b/lib/net/http/generic_request.rb
new file mode 100644
index 0000000000..5b01ea4abd
--- /dev/null
+++ b/lib/net/http/generic_request.rb
@@ -0,0 +1,429 @@
+# frozen_string_literal: true
+#
+# \HTTPGenericRequest is the parent of the Net::HTTPRequest class.
+#
+# Do not use this directly; instead, use a subclass of Net::HTTPRequest.
+#
+# == About the Examples
+#
+# :include: doc/net-http/examples.rdoc
+#
+class Net::HTTPGenericRequest
+
+  include Net::HTTPHeader
+
+  def initialize(m, reqbody, resbody, uri_or_path, initheader = nil) # :nodoc:
+    @method = m
+    @request_has_body = reqbody
+    @response_has_body = resbody
+
+    if URI === uri_or_path then
+      raise ArgumentError, "not an HTTP URI" unless URI::HTTP === uri_or_path
+      hostname = uri_or_path.host
+      raise ArgumentError, "no host component for URI" unless (hostname && hostname.length > 0)
+      @uri = uri_or_path.dup
+      @path = uri_or_path.request_uri
+      raise ArgumentError, "no HTTP request path given" unless @path
+    else
+      @uri = nil
+      raise ArgumentError, "no HTTP request path given" unless uri_or_path
+      raise ArgumentError, "HTTP request path is empty" if uri_or_path.empty?
+      @path = uri_or_path.dup
+    end
+
+    @decode_content = false
+
+    if Net::HTTP::HAVE_ZLIB then
+      if !initheader ||
+         !initheader.keys.any? { |k|
+           %w[accept-encoding range].include? k.downcase
+         } then
+        @decode_content = true if @response_has_body
+        initheader = initheader ? initheader.dup : {}
+        initheader["accept-encoding"] =
+          "gzip;q=1.0,deflate;q=0.6,identity;q=0.3"
+      end
+    end
+
+    initialize_http_header initheader
+    self['Accept'] ||= '*/*'
+    self['User-Agent'] ||= 'Ruby'
+    self['Host'] ||= @uri.authority if @uri
+    @body = nil
+    @body_stream = nil
+    @body_data = nil
+  end
+
+  # Returns the string method name for the request:
+  #
+  #   Net::HTTP::Get.new(uri).method  # => "GET"
+  #   Net::HTTP::Post.new(uri).method # => "POST"
+  #
+  attr_reader :method
+
+  # Returns the string path for the request:
+  #
+  #   Net::HTTP::Get.new(uri).path # => "/"
+  #   Net::HTTP::Post.new('example.com').path # => "example.com"
+  #
+  attr_reader :path
+
+  # Returns the URI object for the request, or +nil+ if none:
+  #
+  #   Net::HTTP::Get.new(uri).uri
+  #   # => #<URI::HTTPS https://jsonplaceholder.typicode.com/>
+  #   Net::HTTP::Get.new('example.com').uri # => nil
+  #
+  attr_reader :uri
+
+  # Returns +false+ if the request's header <tt>'Accept-Encoding'</tt>
+  # has been set manually or deleted
+  # (indicating that the user intends to handle encoding in the response),
+  # +true+ otherwise:
+  #
+  #   req = Net::HTTP::Get.new(uri) # => #<Net::HTTP::Get GET>
+  #   req['Accept-Encoding']        # => "gzip;q=1.0,deflate;q=0.6,identity;q=0.3"
+  #   req.decode_content            # => true
+  #   req['Accept-Encoding'] = 'foo'
+  #   req.decode_content            # => false
+  #   req.delete('Accept-Encoding')
+  #   req.decode_content            # => false
+  #
+  attr_reader :decode_content
+
+  # Returns a string representation of the request:
+  #
+  #   Net::HTTP::Post.new(uri).inspect # => "#<Net::HTTP::Post POST>"
+  #
+  def inspect
+    "\#<#{self.class} #{@method}>"
+  end
+
+  # Returns a string representation of the request with the details for pp:
+  #
+  #   require 'pp'
+  #   post = Net::HTTP::Post.new(uri)
+  #   post.inspect # => "#<Net::HTTP::Post POST>"
+  #   post.pretty_inspect
+  #   # => #<Net::HTTP::Post
+  #         POST
+  #         path="/"
+  #         headers={"accept-encoding" => ["gzip;q=1.0,deflate;q=0.6,identity;q=0.3"],
+  #          "accept" => ["*/*"],
+  #          "user-agent" => ["Ruby"],
+  #          "host" => ["www.ruby-lang.org"]}>
+  #
+  def pretty_print(q)
+    q.object_group(self) {
+      q.breakable
+      q.text @method
+      q.breakable
+      q.text "path="; q.pp @path
+      q.breakable
+      q.text "headers="; q.pp to_hash
+    }
+  end
+
+  ##
+  # Don't automatically decode response content-encoding if the user indicates
+  # they want to handle it.
+
+  def []=(key, val) # :nodoc:
+    @decode_content = false if key.downcase == 'accept-encoding'
+
+    super key, val
+  end
+
+  # Returns whether the request may have a body:
+  #
+  #   Net::HTTP::Post.new(uri).request_body_permitted? # => true
+  #   Net::HTTP::Get.new(uri).request_body_permitted?  # => false
+  #
+  def request_body_permitted?
+    @request_has_body
+  end
+
+  # Returns whether the response may have a body:
+  #
+  #   Net::HTTP::Post.new(uri).response_body_permitted? # => true
+  #   Net::HTTP::Head.new(uri).response_body_permitted? # => false
+  #
+  def response_body_permitted?
+    @response_has_body
+  end
+
+  def body_exist? # :nodoc:
+    warn "Net::HTTPRequest#body_exist? is obsolete; use response_body_permitted?", uplevel: 1 if $VERBOSE
+    response_body_permitted?
+  end
+
+  # Returns the string body for the request, or +nil+ if there is none:
+  #
+  #   req = Net::HTTP::Post.new(uri)
+  #   req.body # => nil
+  #   req.body = '{"title": "foo","body": "bar","userId": 1}'
+  #   req.body # => "{\"title\": \"foo\",\"body\": \"bar\",\"userId\": 1}"
+  #
+  attr_reader :body
+
+  # Sets the body for the request:
+  #
+  #   req = Net::HTTP::Post.new(uri)
+  #   req.body # => nil
+  #   req.body = '{"title": "foo","body": "bar","userId": 1}'
+  #   req.body # => "{\"title\": \"foo\",\"body\": \"bar\",\"userId\": 1}"
+  #
+  def body=(str)
+    @body = str
+    @body_stream = nil
+    @body_data = nil
+    str
+  end
+
+  # Returns the body stream object for the request, or +nil+ if there is none:
+  #
+  #   req = Net::HTTP::Post.new(uri)          # => #<Net::HTTP::Post POST>
+  #   req.body_stream                         # => nil
+  #   require 'stringio'
+  #   req.body_stream = StringIO.new('xyzzy') # => #<StringIO:0x0000027d1e5affa8>
+  #   req.body_stream                         # => #<StringIO:0x0000027d1e5affa8>
+  #
+  attr_reader :body_stream
+
+  # Sets the body stream for the request:
+  #
+  #   req = Net::HTTP::Post.new(uri)          # => #<Net::HTTP::Post POST>
+  #   req.body_stream                         # => nil
+  #   require 'stringio'
+  #   req.body_stream = StringIO.new('xyzzy') # => #<StringIO:0x0000027d1e5affa8>
+  #   req.body_stream                         # => #<StringIO:0x0000027d1e5affa8>
+  #
+  def body_stream=(input)
+    @body = nil
+    @body_stream = input
+    @body_data = nil
+    input
+  end
+
+  def set_body_internal(str)   #:nodoc: internal use only
+    raise ArgumentError, "both of body argument and HTTPRequest#body set" if str and (@body or @body_stream)
+    self.body = str if str
+    if @body.nil? && @body_stream.nil? && @body_data.nil? && request_body_permitted?
+      self.body = ''
+    end
+  end
+
+  #
+  # write
+  #
+
+  def exec(sock, ver, path)   #:nodoc: internal use only
+    if @body
+      send_request_with_body sock, ver, path, @body
+    elsif @body_stream
+      send_request_with_body_stream sock, ver, path, @body_stream
+    elsif @body_data
+      send_request_with_body_data sock, ver, path, @body_data
+    else
+      write_header sock, ver, path
+    end
+  end
+
+  def update_uri(addr, port, ssl) # :nodoc: internal use only
+    # reflect the connection and @path to @uri
+    return unless @uri
+
+    if ssl
+      scheme = 'https'
+      klass = URI::HTTPS
+    else
+      scheme = 'http'
+      klass = URI::HTTP
+    end
+
+    if host = self['host']
+      host = URI.parse("//#{host}").host # Remove a port component from the existing Host header
+    elsif host = @uri.host
+    else
+     host = addr
+    end
+    # convert the class of the URI
+    if @uri.is_a?(klass)
+      @uri.host = host
+      @uri.port = port
+    else
+      @uri = klass.new(
+        scheme, @uri.userinfo,
+        host, port, nil,
+        @uri.path, nil, @uri.query, nil)
+    end
+  end
+
+  private
+
+  # :stopdoc:
+
+  class Chunker #:nodoc:
+    def initialize(sock)
+      @sock = sock
+      @prev = nil
+    end
+
+    def write(buf)
+      # avoid memcpy() of buf, buf can huge and eat memory bandwidth
+      rv = buf.bytesize
+      @sock.write("#{rv.to_s(16)}\r\n", buf, "\r\n")
+      rv
+    end
+
+    def finish
+      @sock.write("0\r\n\r\n")
+    end
+  end
+
+  def send_request_with_body(sock, ver, path, body)
+    self.content_length = body.bytesize
+    delete 'Transfer-Encoding'
+    write_header sock, ver, path
+    wait_for_continue sock, ver if sock.continue_timeout
+    sock.write body
+  end
+
+  def send_request_with_body_stream(sock, ver, path, f)
+    unless content_length() or chunked?
+      raise ArgumentError,
+          "Content-Length not given and Transfer-Encoding is not `chunked'"
+    end
+    write_header sock, ver, path
+    wait_for_continue sock, ver if sock.continue_timeout
+    if chunked?
+      chunker = Chunker.new(sock)
+      IO.copy_stream(f, chunker)
+      chunker.finish
+    else
+      IO.copy_stream(f, sock)
+    end
+  end
+
+  def send_request_with_body_data(sock, ver, path, params)
+    if /\Amultipart\/form-data\z/i !~ self.content_type
+      self.content_type = 'application/x-www-form-urlencoded'
+      return send_request_with_body(sock, ver, path, URI.encode_www_form(params))
+    end
+
+    opt = @form_option.dup
+    require 'securerandom' unless defined?(SecureRandom)
+    opt[:boundary] ||= SecureRandom.urlsafe_base64(40)
+    self.set_content_type(self.content_type, boundary: opt[:boundary])
+    if chunked?
+      write_header sock, ver, path
+      encode_multipart_form_data(sock, params, opt)
+    else
+      require 'tempfile'
+      file = Tempfile.new('multipart')
+      file.binmode
+      encode_multipart_form_data(file, params, opt)
+      file.rewind
+      self.content_length = file.size
+      write_header sock, ver, path
+      IO.copy_stream(file, sock)
+      file.close(true)
+    end
+  end
+
+  def encode_multipart_form_data(out, params, opt)
+    charset = opt[:charset]
+    boundary = opt[:boundary]
+    require 'securerandom' unless defined?(SecureRandom)
+    boundary ||= SecureRandom.urlsafe_base64(40)
+    chunked_p = chunked?
+
+    buf = +''
+    params.each do |key, value, h={}|
+      key = quote_string(key, charset)
+      filename =
+        h.key?(:filename) ? h[:filename] :
+        value.respond_to?(:to_path) ? File.basename(value.to_path) :
+        nil
+
+      buf << "--#{boundary}\r\n"
+      if filename
+        filename = quote_string(filename, charset)
+        type = h[:content_type] || 'application/octet-stream'
+        buf << "Content-Disposition: form-data; " \
+          "name=\"#{key}\"; filename=\"#{filename}\"\r\n" \
+          "Content-Type: #{type}\r\n\r\n"
+        if !out.respond_to?(:write) || !value.respond_to?(:read)
+          # if +out+ is not an IO or +value+ is not an IO
+          buf << (value.respond_to?(:read) ? value.read : value)
+        elsif value.respond_to?(:size) && chunked_p
+          # if +out+ is an IO and +value+ is a File, use IO.copy_stream
+          flush_buffer(out, buf, chunked_p)
+          out << "%x\r\n" % value.size if chunked_p
+          IO.copy_stream(value, out)
+          out << "\r\n" if chunked_p
+        else
+          # +out+ is an IO, and +value+ is not a File but an IO
+          flush_buffer(out, buf, chunked_p)
+          1 while flush_buffer(out, value.read(4096), chunked_p)
+        end
+      else
+        # non-file field:
+        #   HTML5 says, "The parts of the generated multipart/form-data
+        #   resource that correspond to non-file fields must not have a
+        #   Content-Type header specified."
+        buf << "Content-Disposition: form-data; name=\"#{key}\"\r\n\r\n"
+        buf << (value.respond_to?(:read) ? value.read : value)
+      end
+      buf << "\r\n"
+    end
+    buf << "--#{boundary}--\r\n"
+    flush_buffer(out, buf, chunked_p)
+    out << "0\r\n\r\n" if chunked_p
+  end
+
+  def quote_string(str, charset)
+    str = str.encode(charset, fallback:->(c){'&#%d;'%c.encode("UTF-8").ord}) if charset
+    str.gsub(/[\\"]/, '\\\\\&')
+  end
+
+  def flush_buffer(out, buf, chunked_p)
+    return unless buf
+    out << "%x\r\n"%buf.bytesize if chunked_p
+    out << buf
+    out << "\r\n" if chunked_p
+    buf.clear
+  end
+
+  ##
+  # Waits up to the continue timeout for a response from the server provided
+  # we're speaking HTTP 1.1 and are expecting a 100-continue response.
+
+  def wait_for_continue(sock, ver)
+    if ver >= '1.1' and @header['expect'] and
+        @header['expect'].include?('100-continue')
+      if sock.io.to_io.wait_readable(sock.continue_timeout)
+        res = Net::HTTPResponse.read_new(sock)
+        unless res.kind_of?(Net::HTTPContinue)
+          res.decode_content = @decode_content
+          throw :response, res
+        end
+      end
+    end
+  end
+
+  def write_header(sock, ver, path)
+    reqline = "#{@method} #{path} HTTP/#{ver}"
+    if /[\r\n]/ =~ reqline
+      raise ArgumentError, "A Request-Line must not contain CR or LF"
+    end
+    buf = +''
+    buf << reqline << "\r\n"
+    each_capitalized do |k,v|
+      buf << "#{k}: #{v}\r\n"
+    end
+    buf << "\r\n"
+    sock.write buf
+  end
+
+end
diff --git a/lib/net/http/header.rb b/lib/net/http/header.rb
new file mode 100644
index 0000000000..5dcdcc7d74
--- /dev/null
+++ b/lib/net/http/header.rb
@@ -0,0 +1,985 @@
+# frozen_string_literal: true
+#
+# The \HTTPHeader module provides access to \HTTP headers.
+#
+# The module is included in:
+#
+# - Net::HTTPGenericRequest (and therefore Net::HTTPRequest).
+# - Net::HTTPResponse.
+#
+# The headers are a hash-like collection of key/value pairs called _fields_.
+#
+# == Request and Response Fields
+#
+# Headers may be included in:
+#
+# - A Net::HTTPRequest object:
+#   the object's headers will be sent with the request.
+#   Any fields may be defined in the request;
+#   see {Setters}[rdoc-ref:Net::HTTPHeader@Setters].
+# - A Net::HTTPResponse object:
+#   the objects headers are usually those returned from the host.
+#   Fields may be retrieved from the object;
+#   see {Getters}[rdoc-ref:Net::HTTPHeader@Getters]
+#   and {Iterators}[rdoc-ref:Net::HTTPHeader@Iterators].
+#
+# Exactly which fields should be sent or expected depends on the host;
+# see:
+#
+# - {Request fields}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#Request_fields].
+# - {Response fields}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#Response_fields].
+#
+# == About the Examples
+#
+# :include: doc/net-http/examples.rdoc
+#
+# == Fields
+#
+# A header field is a key/value pair.
+#
+# === Field Keys
+#
+# A field key may be:
+#
+# - A string: Key <tt>'Accept'</tt> is treated as if it were
+#   <tt>'Accept'.downcase</tt>;  i.e., <tt>'accept'</tt>.
+# - A symbol: Key <tt>:Accept</tt> is treated as if it were
+#   <tt>:Accept.to_s.downcase</tt>;  i.e., <tt>'accept'</tt>.
+#
+# Examples:
+#
+#   req = Net::HTTP::Get.new(uri)
+#   req[:accept]  # => "*/*"
+#   req['Accept'] # => "*/*"
+#   req['ACCEPT'] # => "*/*"
+#
+#   req['accept'] = 'text/html'
+#   req[:accept] = 'text/html'
+#   req['ACCEPT'] = 'text/html'
+#
+# === Field Values
+#
+# A field value may be returned as an array of strings or as a string:
+#
+# - These methods return field values as arrays:
+#
+#   - #get_fields: Returns the array value for the given key,
+#     or +nil+ if it does not exist.
+#   - #to_hash: Returns a hash of all header fields:
+#     each key is a field name; its value is the array value for the field.
+#
+# - These methods return field values as string;
+#   the string value for a field is equivalent to
+#   <tt>self[key.downcase.to_s].join(', '))</tt>:
+#
+#   - #[]: Returns the string value for the given key,
+#     or +nil+ if it does not exist.
+#   - #fetch: Like #[], but accepts a default value
+#     to be returned if the key does not exist.
+#
+# The field value may be set:
+#
+# - #[]=: Sets the value for the given key;
+#   the given value may be a string, a symbol, an array, or a hash.
+# - #add_field: Adds a given value to a value for the given key
+#   (not overwriting the existing value).
+# - #delete: Deletes the field for the given key.
+#
+# Example field values:
+#
+# - \String:
+#
+#     req['Accept'] = 'text/html' # => "text/html"
+#     req['Accept']               # => "text/html"
+#     req.get_fields('Accept')    # => ["text/html"]
+#
+# - \Symbol:
+#
+#     req['Accept'] = :text    # => :text
+#     req['Accept']            # => "text"
+#     req.get_fields('Accept') # => ["text"]
+#
+# - Simple array:
+#
+#     req[:foo] = %w[bar baz bat]
+#     req[:foo]            # => "bar, baz, bat"
+#     req.get_fields(:foo) # => ["bar", "baz", "bat"]
+#
+# - Simple hash:
+#
+#     req[:foo] = {bar: 0, baz: 1, bat: 2}
+#     req[:foo]            # => "bar, 0, baz, 1, bat, 2"
+#     req.get_fields(:foo) # => ["bar", "0", "baz", "1", "bat", "2"]
+#
+# - Nested:
+#
+#     req[:foo] = [%w[bar baz], {bat: 0, bam: 1}]
+#     req[:foo]            # => "bar, baz, bat, 0, bam, 1"
+#     req.get_fields(:foo) # => ["bar", "baz", "bat", "0", "bam", "1"]
+#
+#     req[:foo] = {bar: %w[baz bat], bam: {bah: 0, bad: 1}}
+#     req[:foo]            # => "bar, baz, bat, bam, bah, 0, bad, 1"
+#     req.get_fields(:foo) # => ["bar", "baz", "bat", "bam", "bah", "0", "bad", "1"]
+#
+# == Convenience Methods
+#
+# Various convenience methods retrieve values, set values, query values,
+# set form values, or iterate over fields.
+#
+# === Setters
+#
+# \Method #[]= can set any field, but does little to validate the new value;
+# some of the other setter methods provide some validation:
+#
+# - #[]=: Sets the string or array value for the given key.
+# - #add_field: Creates or adds to the array value for the given key.
+# - #basic_auth: Sets the string authorization header for <tt>'Authorization'</tt>.
+# - #content_length=: Sets the integer length for field <tt>'Content-Length</tt>.
+# - #content_type=: Sets the string value for field <tt>'Content-Type'</tt>.
+# - #proxy_basic_auth: Sets the string authorization header for <tt>'Proxy-Authorization'</tt>.
+# - #set_range: Sets the value for field <tt>'Range'</tt>.
+#
+# === Form Setters
+#
+# - #set_form: Sets an HTML form data set.
+# - #set_form_data: Sets header fields and a body from HTML form data.
+#
+# === Getters
+#
+# \Method #[] can retrieve the value of any field that exists,
+# but always as a string;
+# some of the other getter methods return something different
+# from the simple string value:
+#
+# - #[]: Returns the string field value for the given key.
+# - #content_length: Returns the integer value of field <tt>'Content-Length'</tt>.
+# - #content_range: Returns the Range value of field <tt>'Content-Range'</tt>.
+# - #content_type: Returns the string value of field <tt>'Content-Type'</tt>.
+# - #fetch: Returns the string field value for the given key.
+# - #get_fields: Returns the array field value for the given +key+.
+# - #main_type: Returns first part of the string value of field <tt>'Content-Type'</tt>.
+# - #sub_type: Returns second part of the string value of field <tt>'Content-Type'</tt>.
+# - #range: Returns an array of Range objects of field <tt>'Range'</tt>, or +nil+.
+# - #range_length: Returns the integer length of the range given in field <tt>'Content-Range'</tt>.
+# - #type_params: Returns the string parameters for <tt>'Content-Type'</tt>.
+#
+# === Queries
+#
+# - #chunked?: Returns whether field <tt>'Transfer-Encoding'</tt> is set to <tt>'chunked'</tt>.
+# - #connection_close?: Returns whether field <tt>'Connection'</tt> is set to <tt>'close'</tt>.
+# - #connection_keep_alive?: Returns whether field <tt>'Connection'</tt> is set to <tt>'keep-alive'</tt>.
+# - #key?: Returns whether a given key exists.
+#
+# === Iterators
+#
+# - #each_capitalized: Passes each field capitalized-name/value pair to the block.
+# - #each_capitalized_name: Passes each capitalized field name to the block.
+# - #each_header: Passes each field name/value pair to the block.
+# - #each_name: Passes each field name to the block.
+# - #each_value: Passes each string field value to the block.
+#
+module Net::HTTPHeader
+  # The maximum length of HTTP header keys.
+  MAX_KEY_LENGTH = 1024
+  # The maximum length of HTTP header values.
+  MAX_FIELD_LENGTH = 65536
+
+  def initialize_http_header(initheader) #:nodoc:
+    @header = {}
+    return unless initheader
+    initheader.each do |key, value|
+      warn "net/http: duplicated HTTP header: #{key}", uplevel: 3 if key?(key) and $VERBOSE
+      if value.nil?
+        warn "net/http: nil HTTP header: #{key}", uplevel: 3 if $VERBOSE
+      else
+        value = value.strip # raise error for invalid byte sequences
+        if key.to_s.bytesize > MAX_KEY_LENGTH
+          raise ArgumentError, "too long (#{key.bytesize} bytes) header: #{key[0, 30].inspect}..."
+        end
+        if value.to_s.bytesize > MAX_FIELD_LENGTH
+          raise ArgumentError, "header #{key} has too long field value: #{value.bytesize}"
+        end
+        if value.count("\r\n") > 0
+          raise ArgumentError, "header #{key} has field value #{value.inspect}, this cannot include CR/LF"
+        end
+        @header[key.downcase.to_s] = [value]
+      end
+    end
+  end
+
+  def size   #:nodoc: obsolete
+    @header.size
+  end
+
+  alias length size   #:nodoc: obsolete
+
+  # Returns the string field value for the case-insensitive field +key+,
+  # or +nil+ if there is no such key;
+  # see {Fields}[rdoc-ref:Net::HTTPHeader@Fields]:
+  #
+  #   res = Net::HTTP.get_response(hostname, '/todos/1')
+  #   res['Connection'] # => "keep-alive"
+  #   res['Nosuch']     # => nil
+  #
+  # Note that some field values may be retrieved via convenience methods;
+  # see {Getters}[rdoc-ref:Net::HTTPHeader@Getters].
+  def [](key)
+    a = @header[key.downcase.to_s] or return nil
+    a.join(', ')
+  end
+
+  # Sets the value for the case-insensitive +key+ to +val+,
+  # overwriting the previous value if the field exists;
+  # see {Fields}[rdoc-ref:Net::HTTPHeader@Fields]:
+  #
+  #   req = Net::HTTP::Get.new(uri)
+  #   req['Accept'] # => "*/*"
+  #   req['Accept'] = 'text/html'
+  #   req['Accept'] # => "text/html"
+  #
+  # Note that some field values may be set via convenience methods;
+  # see {Setters}[rdoc-ref:Net::HTTPHeader@Setters].
+  def []=(key, val)
+    unless val
+      @header.delete key.downcase.to_s
+      return val
+    end
+    set_field(key, val)
+  end
+
+  # Adds value +val+ to the value array for field +key+ if the field exists;
+  # creates the field with the given +key+ and +val+ if it does not exist.
+  # see {Fields}[rdoc-ref:Net::HTTPHeader@Fields]:
+  #
+  #   req = Net::HTTP::Get.new(uri)
+  #   req.add_field('Foo', 'bar')
+  #   req['Foo']            # => "bar"
+  #   req.add_field('Foo', 'baz')
+  #   req['Foo']            # => "bar, baz"
+  #   req.add_field('Foo', %w[baz bam])
+  #   req['Foo']            # => "bar, baz, baz, bam"
+  #   req.get_fields('Foo') # => ["bar", "baz", "baz", "bam"]
+  #
+  def add_field(key, val)
+    stringified_downcased_key = key.downcase.to_s
+    if @header.key?(stringified_downcased_key)
+      append_field_value(@header[stringified_downcased_key], val)
+    else
+      set_field(key, val)
+    end
+  end
+
+  # :stopdoc:
+  private def set_field(key, val)
+    case val
+    when Enumerable
+      ary = []
+      append_field_value(ary, val)
+      @header[key.downcase.to_s] = ary
+    else
+      val = val.to_s # for compatibility use to_s instead of to_str
+      if val.b.count("\r\n") > 0
+        raise ArgumentError, 'header field value cannot include CR/LF'
+      end
+      @header[key.downcase.to_s] = [val]
+    end
+  end
+
+  private def append_field_value(ary, val)
+    case val
+    when Enumerable
+      val.each{|x| append_field_value(ary, x)}
+    else
+      val = val.to_s
+      if /[\r\n]/n.match?(val.b)
+        raise ArgumentError, 'header field value cannot include CR/LF'
+      end
+      ary.push val
+    end
+  end
+  # :startdoc:
+
+  # Returns the array field value for the given +key+,
+  # or +nil+ if there is no such field;
+  # see {Fields}[rdoc-ref:Net::HTTPHeader@Fields]:
+  #
+  #   res = Net::HTTP.get_response(hostname, '/todos/1')
+  #   res.get_fields('Connection') # => ["keep-alive"]
+  #   res.get_fields('Nosuch')     # => nil
+  #
+  def get_fields(key)
+    stringified_downcased_key = key.downcase.to_s
+    return nil unless @header[stringified_downcased_key]
+    @header[stringified_downcased_key].dup
+  end
+
+  # call-seq:
+  #   fetch(key, default_val = nil) {|key| ... } -> object
+  #   fetch(key, default_val = nil) -> value or default_val
+  #
+  # With a block, returns the string value for +key+ if it exists;
+  # otherwise returns the value of the block;
+  # ignores the +default_val+;
+  # see {Fields}[rdoc-ref:Net::HTTPHeader@Fields]:
+  #
+  #   res = Net::HTTP.get_response(hostname, '/todos/1')
+  #
+  #   # Field exists; block not called.
+  #   res.fetch('Connection') do |value|
+  #     fail 'Cannot happen'
+  #   end # => "keep-alive"
+  #
+  #   # Field does not exist; block called.
+  #   res.fetch('Nosuch') do |value|
+  #     value.downcase
+  #   end # => "nosuch"
+  #
+  # With no block, returns the string value for +key+ if it exists;
+  # otherwise, returns +default_val+ if it was given;
+  # otherwise raises an exception:
+  #
+  #   res.fetch('Connection', 'Foo') # => "keep-alive"
+  #   res.fetch('Nosuch', 'Foo')     # => "Foo"
+  #   res.fetch('Nosuch')            # Raises KeyError.
+  #
+  def fetch(key, *args, &block)   #:yield: +key+
+    a = @header.fetch(key.downcase.to_s, *args, &block)
+    a.kind_of?(Array) ? a.join(', ') : a
+  end
+
+  # Calls the block with each key/value pair:
+  #
+  #   res = Net::HTTP.get_response(hostname, '/todos/1')
+  #   res.each_header do |key, value|
+  #     p [key, value] if key.start_with?('c')
+  #   end
+  #
+  # Output:
+  #
+  #   ["content-type", "application/json; charset=utf-8"]
+  #   ["connection", "keep-alive"]
+  #   ["cache-control", "max-age=43200"]
+  #   ["cf-cache-status", "HIT"]
+  #   ["cf-ray", "771d17e9bc542cf5-ORD"]
+  #
+  # Returns an enumerator if no block is given.
+  #
+  # Net::HTTPHeader#each is an alias for Net::HTTPHeader#each_header.
+  def each_header   #:yield: +key+, +value+
+    block_given? or return enum_for(__method__) { @header.size }
+    @header.each do |k,va|
+      yield k, va.join(', ')
+    end
+  end
+
+  alias each each_header
+
+  # Calls the block with each field key:
+  #
+  #   res = Net::HTTP.get_response(hostname, '/todos/1')
+  #   res.each_key do |key|
+  #     p key if key.start_with?('c')
+  #   end
+  #
+  # Output:
+  #
+  #   "content-type"
+  #   "connection"
+  #   "cache-control"
+  #   "cf-cache-status"
+  #   "cf-ray"
+  #
+  # Returns an enumerator if no block is given.
+  #
+  # Net::HTTPHeader#each_name is an alias for Net::HTTPHeader#each_key.
+  def each_name(&block)   #:yield: +key+
+    block_given? or return enum_for(__method__) { @header.size }
+    @header.each_key(&block)
+  end
+
+  alias each_key each_name
+
+  # Calls the block with each capitalized field name:
+  #
+  #   res = Net::HTTP.get_response(hostname, '/todos/1')
+  #   res.each_capitalized_name do |key|
+  #     p key if key.start_with?('C')
+  #   end
+  #
+  # Output:
+  #
+  #   "Content-Type"
+  #   "Connection"
+  #   "Cache-Control"
+  #   "Cf-Cache-Status"
+  #   "Cf-Ray"
+  #
+  # The capitalization is system-dependent;
+  # see {Case Mapping}[rdoc-ref:case_mapping.rdoc].
+  #
+  # Returns an enumerator if no block is given.
+  def each_capitalized_name  #:yield: +key+
+    block_given? or return enum_for(__method__) { @header.size }
+    @header.each_key do |k|
+      yield capitalize(k)
+    end
+  end
+
+  # Calls the block with each string field value:
+  #
+  #   res = Net::HTTP.get_response(hostname, '/todos/1')
+  #   res.each_value do |value|
+  #     p value if value.start_with?('c')
+  #   end
+  #
+  # Output:
+  #
+  #   "chunked"
+  #   "cf-q-config;dur=6.0000002122251e-06"
+  #   "cloudflare"
+  #
+  # Returns an enumerator if no block is given.
+  def each_value   #:yield: +value+
+    block_given? or return enum_for(__method__) { @header.size }
+    @header.each_value do |va|
+      yield va.join(', ')
+    end
+  end
+
+  # Removes the header for the given case-insensitive +key+
+  # (see {Fields}[rdoc-ref:Net::HTTPHeader@Fields]);
+  # returns the deleted value, or +nil+ if no such field exists:
+  #
+  #   req = Net::HTTP::Get.new(uri)
+  #   req.delete('Accept') # => ["*/*"]
+  #   req.delete('Nosuch') # => nil
+  #
+  def delete(key)
+    @header.delete(key.downcase.to_s)
+  end
+
+  # Returns +true+ if the field for the case-insensitive +key+ exists, +false+ otherwise:
+  #
+  #   req = Net::HTTP::Get.new(uri)
+  #   req.key?('Accept') # => true
+  #   req.key?('Nosuch') # => false
+  #
+  def key?(key)
+    @header.key?(key.downcase.to_s)
+  end
+
+  # Returns a hash of the key/value pairs:
+  #
+  #   req = Net::HTTP::Get.new(uri)
+  #   req.to_hash
+  #   # =>
+  #   {"accept-encoding"=>["gzip;q=1.0,deflate;q=0.6,identity;q=0.3"],
+  #    "accept"=>["*/*"],
+  #    "user-agent"=>["Ruby"],
+  #    "host"=>["jsonplaceholder.typicode.com"]}
+  #
+  def to_hash
+    @header.dup
+  end
+
+  # Like #each_header, but the keys are returned in capitalized form.
+  #
+  # Net::HTTPHeader#canonical_each is an alias for Net::HTTPHeader#each_capitalized.
+  def each_capitalized
+    block_given? or return enum_for(__method__) { @header.size }
+    @header.each do |k,v|
+      yield capitalize(k), v.join(', ')
+    end
+  end
+
+  alias canonical_each each_capitalized
+
+  def capitalize(name)  # :nodoc:
+    name.to_s.split('-'.freeze).map {|s| s.capitalize }.join('-'.freeze)
+  end
+  private :capitalize
+
+  # Returns an array of Range objects that represent
+  # the value of field <tt>'Range'</tt>,
+  # or +nil+ if there is no such field;
+  # see {Range request header}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#range-request-header]:
+  #
+  #   req = Net::HTTP::Get.new(uri)
+  #   req['Range'] = 'bytes=0-99,200-299,400-499'
+  #   req.range # => [0..99, 200..299, 400..499]
+  #   req.delete('Range')
+  #   req.range # # => nil
+  #
+  def range
+    return nil unless @header['range']
+
+    value = self['Range']
+    # byte-range-set = *( "," OWS ) ( byte-range-spec / suffix-byte-range-spec )
+    #   *( OWS "," [ OWS ( byte-range-spec / suffix-byte-range-spec ) ] )
+    # corrected collected ABNF
+    # http://tools.ietf.org/html/draft-ietf-httpbis-p5-range-19#section-5.4.1
+    # http://tools.ietf.org/html/draft-ietf-httpbis-p5-range-19#appendix-C
+    # http://tools.ietf.org/html/draft-ietf-httpbis-p1-messaging-19#section-3.2.5
+    unless /\Abytes=((?:,[ \t]*)*(?:\d+-\d*|-\d+)(?:[ \t]*,(?:[ \t]*\d+-\d*|-\d+)?)*)\z/ =~ value
+      raise Net::HTTPHeaderSyntaxError, "invalid syntax for byte-ranges-specifier: '#{value}'"
+    end
+
+    byte_range_set = $1
+    result = byte_range_set.split(/,/).map {|spec|
+      m = /(\d+)?\s*-\s*(\d+)?/i.match(spec) or
+              raise Net::HTTPHeaderSyntaxError, "invalid byte-range-spec: '#{spec}'"
+      d1 = m[1].to_i
+      d2 = m[2].to_i
+      if m[1] and m[2]
+        if d1 > d2
+          raise Net::HTTPHeaderSyntaxError, "last-byte-pos MUST greater than or equal to first-byte-pos but '#{spec}'"
+        end
+        d1..d2
+      elsif m[1]
+        d1..-1
+      elsif m[2]
+        -d2..-1
+      else
+        raise Net::HTTPHeaderSyntaxError, 'range is not specified'
+      end
+    }
+    # if result.empty?
+    # byte-range-set must include at least one byte-range-spec or suffix-byte-range-spec
+    # but above regexp already denies it.
+    if result.size == 1 && result[0].begin == 0 && result[0].end == -1
+      raise Net::HTTPHeaderSyntaxError, 'only one suffix-byte-range-spec with zero suffix-length'
+    end
+    result
+  end
+
+  # call-seq:
+  #   set_range(length) -> length
+  #   set_range(offset, length) -> range
+  #   set_range(begin..length) -> range
+  #
+  # Sets the value for field <tt>'Range'</tt>;
+  # see {Range request header}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#range-request-header]:
+  #
+  # With argument +length+:
+  #
+  #   req = Net::HTTP::Get.new(uri)
+  #   req.set_range(100)      # => 100
+  #   req['Range']            # => "bytes=0-99"
+  #
+  # With arguments +offset+ and +length+:
+  #
+  #   req.set_range(100, 100) # => 100...200
+  #   req['Range']            # => "bytes=100-199"
+  #
+  # With argument +range+:
+  #
+  #   req.set_range(100..199) # => 100..199
+  #   req['Range']            # => "bytes=100-199"
+  #
+  # Net::HTTPHeader#range= is an alias for Net::HTTPHeader#set_range.
+  def set_range(r, e = nil)
+    unless r
+      @header.delete 'range'
+      return r
+    end
+    r = (r...r+e) if e
+    case r
+    when Numeric
+      n = r.to_i
+      rangestr = (n > 0 ? "0-#{n-1}" : "-#{-n}")
+    when Range
+      first = r.first
+      last = r.end
+      last -= 1 if r.exclude_end?
+      if last == -1
+        rangestr = (first > 0 ? "#{first}-" : "-#{-first}")
+      else
+        raise Net::HTTPHeaderSyntaxError, 'range.first is negative' if first < 0
+        raise Net::HTTPHeaderSyntaxError, 'range.last is negative' if last < 0
+        raise Net::HTTPHeaderSyntaxError, 'must be .first < .last' if first > last
+        rangestr = "#{first}-#{last}"
+      end
+    else
+      raise TypeError, 'Range/Integer is required'
+    end
+    @header['range'] = ["bytes=#{rangestr}"]
+    r
+  end
+
+  alias range= set_range
+
+  # Returns the value of field <tt>'Content-Length'</tt> as an integer,
+  # or +nil+ if there is no such field;
+  # see {Content-Length request header}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#content-length-request-header]:
+  #
+  #   res = Net::HTTP.get_response(hostname, '/nosuch/1')
+  #   res.content_length # => 2
+  #   res = Net::HTTP.get_response(hostname, '/todos/1')
+  #   res.content_length # => nil
+  #
+  def content_length
+    return nil unless key?('Content-Length')
+    len = self['Content-Length'].slice(/\d+/) or
+        raise Net::HTTPHeaderSyntaxError, 'wrong Content-Length format'
+    len.to_i
+  end
+
+  # Sets the value of field <tt>'Content-Length'</tt> to the given numeric;
+  # see {Content-Length response header}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#content-length-response-header]:
+  #
+  #   _uri = uri.dup
+  #   hostname = _uri.hostname           # => "jsonplaceholder.typicode.com"
+  #   _uri.path = '/posts'               # => "/posts"
+  #   req = Net::HTTP::Post.new(_uri)    # => #<Net::HTTP::Post POST>
+  #   req.body = '{"title": "foo","body": "bar","userId": 1}'
+  #   req.content_length = req.body.size # => 42
+  #   req.content_type = 'application/json'
+  #   res = Net::HTTP.start(hostname) do |http|
+  #     http.request(req)
+  #   end # => #<Net::HTTPCreated 201 Created readbody=true>
+  #
+  def content_length=(len)
+    unless len
+      @header.delete 'content-length'
+      return nil
+    end
+    @header['content-length'] = [len.to_i.to_s]
+  end
+
+  # Returns +true+ if field <tt>'Transfer-Encoding'</tt>
+  # exists and has value <tt>'chunked'</tt>,
+  # +false+ otherwise;
+  # see {Transfer-Encoding response header}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#transfer-encoding-response-header]:
+  #
+  #   res = Net::HTTP.get_response(hostname, '/todos/1')
+  #   res['Transfer-Encoding'] # => "chunked"
+  #   res.chunked?             # => true
+  #
+  def chunked?
+    return false unless @header['transfer-encoding']
+    field = self['Transfer-Encoding']
+    (/(?:\A|[^\-\w])chunked(?![\-\w])/i =~ field) ? true : false
+  end
+
+  # Returns a Range object representing the value of field
+  # <tt>'Content-Range'</tt>, or +nil+ if no such field exists;
+  # see {Content-Range response header}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#content-range-response-header]:
+  #
+  #   res = Net::HTTP.get_response(hostname, '/todos/1')
+  #   res['Content-Range'] # => nil
+  #   res['Content-Range'] = 'bytes 0-499/1000'
+  #   res['Content-Range'] # => "bytes 0-499/1000"
+  #   res.content_range    # => 0..499
+  #
+  def content_range
+    return nil unless @header['content-range']
+    m = %r<\A\s*(\w+)\s+(\d+)-(\d+)/(\d+|\*)>.match(self['Content-Range']) or
+        raise Net::HTTPHeaderSyntaxError, 'wrong Content-Range format'
+    return unless m[1] == 'bytes'
+    m[2].to_i .. m[3].to_i
+  end
+
+  # Returns the integer representing length of the value of field
+  # <tt>'Content-Range'</tt>, or +nil+ if no such field exists;
+  # see {Content-Range response header}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#content-range-response-header]:
+  #
+  #   res = Net::HTTP.get_response(hostname, '/todos/1')
+  #   res['Content-Range'] # => nil
+  #   res['Content-Range'] = 'bytes 0-499/1000'
+  #   res.range_length     # => 500
+  #
+  def range_length
+    r = content_range() or return nil
+    r.end - r.begin + 1
+  end
+
+  # Returns the {media type}[https://en.wikipedia.org/wiki/Media_type]
+  # from the value of field <tt>'Content-Type'</tt>,
+  # or +nil+ if no such field exists;
+  # see {Content-Type response header}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#content-type-response-header]:
+  #
+  #   res = Net::HTTP.get_response(hostname, '/todos/1')
+  #   res['content-type'] # => "application/json; charset=utf-8"
+  #   res.content_type    # => "application/json"
+  #
+  def content_type
+    main = main_type()
+    return nil unless main
+
+    sub = sub_type()
+    if sub
+      "#{main}/#{sub}"
+    else
+      main
+    end
+  end
+
+  # Returns the leading ('type') part of the
+  # {media type}[https://en.wikipedia.org/wiki/Media_type]
+  # from the value of field <tt>'Content-Type'</tt>,
+  # or +nil+ if no such field exists;
+  # see {Content-Type response header}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#content-type-response-header]:
+  #
+  #   res = Net::HTTP.get_response(hostname, '/todos/1')
+  #   res['content-type'] # => "application/json; charset=utf-8"
+  #   res.main_type       # => "application"
+  #
+  def main_type
+    return nil unless @header['content-type']
+    self['Content-Type'].split(';').first.to_s.split('/')[0].to_s.strip
+  end
+
+  # Returns the trailing ('subtype') part of the
+  # {media type}[https://en.wikipedia.org/wiki/Media_type]
+  # from the value of field <tt>'Content-Type'</tt>,
+  # or +nil+ if no such field exists;
+  # see {Content-Type response header}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#content-type-response-header]:
+  #
+  #   res = Net::HTTP.get_response(hostname, '/todos/1')
+  #   res['content-type'] # => "application/json; charset=utf-8"
+  #   res.sub_type        # => "json"
+  #
+  def sub_type
+    return nil unless @header['content-type']
+    _, sub = *self['Content-Type'].split(';').first.to_s.split('/')
+    return nil unless sub
+    sub.strip
+  end
+
+  # Returns the trailing ('parameters') part of the value of field <tt>'Content-Type'</tt>,
+  # or +nil+ if no such field exists;
+  # see {Content-Type response header}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#content-type-response-header]:
+  #
+  #   res = Net::HTTP.get_response(hostname, '/todos/1')
+  #   res['content-type'] # => "application/json; charset=utf-8"
+  #   res.type_params     # => {"charset"=>"utf-8"}
+  #
+  def type_params
+    result = {}
+    list = self['Content-Type'].to_s.split(';')
+    list.shift
+    list.each do |param|
+      k, v = *param.split('=', 2)
+      result[k.strip] = v.strip
+    end
+    result
+  end
+
+  # Sets the value of field <tt>'Content-Type'</tt>;
+  # returns the new value;
+  # see {Content-Type request header}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#content-type-request-header]:
+  #
+  #   req = Net::HTTP::Get.new(uri)
+  #   req.set_content_type('application/json') # => ["application/json"]
+  #
+  # Net::HTTPHeader#content_type= is an alias for Net::HTTPHeader#set_content_type.
+  def set_content_type(type, params = {})
+    @header['content-type'] = [type + params.map{|k,v|"; #{k}=#{v}"}.join('')]
+  end
+
+  alias content_type= set_content_type
+
+  # Sets the request body to a URL-encoded string derived from argument +params+,
+  # and sets request header field <tt>'Content-Type'</tt>
+  # to <tt>'application/x-www-form-urlencoded'</tt>.
+  #
+  # The resulting request is suitable for HTTP request +POST+ or +PUT+.
+  #
+  # Argument +params+ must be suitable for use as argument +enum+ to
+  # {URI.encode_www_form}[rdoc-ref:URI.encode_www_form].
+  #
+  # With only argument +params+ given,
+  # sets the body to a URL-encoded string with the default separator <tt>'&'</tt>:
+  #
+  #   req = Net::HTTP::Post.new('example.com')
+  #
+  #   req.set_form_data(q: 'ruby', lang: 'en')
+  #   req.body            # => "q=ruby&lang=en"
+  #   req['Content-Type'] # => "application/x-www-form-urlencoded"
+  #
+  #   req.set_form_data([['q', 'ruby'], ['lang', 'en']])
+  #   req.body            # => "q=ruby&lang=en"
+  #
+  #   req.set_form_data(q: ['ruby', 'perl'], lang: 'en')
+  #   req.body            # => "q=ruby&q=perl&lang=en"
+  #
+  #   req.set_form_data([['q', 'ruby'], ['q', 'perl'], ['lang', 'en']])
+  #   req.body            # => "q=ruby&q=perl&lang=en"
+  #
+  # With string argument +sep+ also given,
+  # uses that string as the separator:
+  #
+  #   req.set_form_data({q: 'ruby', lang: 'en'}, '|')
+  #   req.body # => "q=ruby|lang=en"
+  #
+  # Net::HTTPHeader#form_data= is an alias for Net::HTTPHeader#set_form_data.
+  def set_form_data(params, sep = '&')
+    query = URI.encode_www_form(params)
+    query.gsub!(/&/, sep) if sep != '&'
+    self.body = query
+    self.content_type = 'application/x-www-form-urlencoded'
+  end
+
+  alias form_data= set_form_data
+
+  # Stores form data to be used in a +POST+ or +PUT+ request.
+  #
+  # The form data given in +params+ consists of zero or more fields;
+  # each field is:
+  #
+  # - A scalar value.
+  # - A name/value pair.
+  # - An IO stream opened for reading.
+  #
+  # Argument +params+ should be an
+  # {Enumerable}[rdoc-ref:Enumerable@Enumerable+in+Ruby+Classes]
+  # (method <tt>params.map</tt> will be called),
+  # and is often an array or hash.
+  #
+  # First, we set up a request:
+  #
+  #   _uri = uri.dup
+  #   _uri.path ='/posts'
+  #   req = Net::HTTP::Post.new(_uri)
+  #
+  # <b>Argument +params+ As an Array</b>
+  #
+  # When +params+ is an array,
+  # each of its elements is a subarray that defines a field;
+  # the subarray may contain:
+  #
+  # - One string:
+  #
+  #     req.set_form([['foo'], ['bar'], ['baz']])
+  #
+  # - Two strings:
+  #
+  #     req.set_form([%w[foo 0], %w[bar 1], %w[baz 2]])
+  #
+  # - When argument +enctype+ (see below) is given as
+  #   <tt>'multipart/form-data'</tt>:
+  #
+  #   - A string name and an IO stream opened for reading:
+  #
+  #       require 'stringio'
+  #       req.set_form([['file', StringIO.new('Ruby is cool.')]])
+  #
+  #   - A string name, an IO stream opened for reading,
+  #     and an options hash, which may contain these entries:
+  #
+  #     - +:filename+: The name of the file to use.
+  #     - +:content_type+: The content type of the uploaded file.
+  #
+  #     Example:
+  #
+  #       req.set_form([['file', file, {filename: "other-filename.foo"}]]
+  #
+  # The various forms may be mixed:
+  #
+  #   req.set_form(['foo', %w[bar 1], ['file', file]])
+  #
+  # <b>Argument +params+ As a Hash</b>
+  #
+  # When +params+ is a hash,
+  # each of its entries is a name/value pair that defines a field:
+  #
+  # - The name is a string.
+  # - The value may be:
+  #
+  #   - +nil+.
+  #   - Another string.
+  #   - An IO stream opened for reading
+  #     (only when argument +enctype+ -- see below -- is given as
+  #     <tt>'multipart/form-data'</tt>).
+  #
+  # Examples:
+  #
+  #   # Nil-valued fields.
+  #   req.set_form({'foo' => nil, 'bar' => nil, 'baz' => nil})
+  #
+  #   # String-valued fields.
+  #   req.set_form({'foo' => 0, 'bar' => 1, 'baz' => 2})
+  #
+  #   # IO-valued field.
+  #   require 'stringio'
+  #   req.set_form({'file' => StringIO.new('Ruby is cool.')})
+  #
+  #   # Mixture of fields.
+  #   req.set_form({'foo' => nil, 'bar' => 1, 'file' => file})
+  #
+  # Optional argument +enctype+ specifies the value to be given
+  # to field <tt>'Content-Type'</tt>, and must be one of:
+  #
+  # - <tt>'application/x-www-form-urlencoded'</tt> (the default).
+  # - <tt>'multipart/form-data'</tt>;
+  #   see {RFC 7578}[https://www.rfc-editor.org/rfc/rfc7578].
+  #
+  # Optional argument +formopt+ is a hash of options
+  # (applicable only when argument +enctype+
+  # is <tt>'multipart/form-data'</tt>)
+  # that may include the following entries:
+  #
+  # - +:boundary+: The value is the boundary string for the multipart message.
+  #   If not given, the boundary is a random string.
+  #   See {Boundary}[https://www.rfc-editor.org/rfc/rfc7578#section-4.1].
+  # - +:charset+: Value is the character set for the form submission.
+  #   Field names and values of non-file fields should be encoded with this charset.
+  #
+  def set_form(params, enctype='application/x-www-form-urlencoded', formopt={})
+    @body_data = params
+    @body = nil
+    @body_stream = nil
+    @form_option = formopt
+    case enctype
+    when /\Aapplication\/x-www-form-urlencoded\z/i,
+      /\Amultipart\/form-data\z/i
+      self.content_type = enctype
+    else
+      raise ArgumentError, "invalid enctype: #{enctype}"
+    end
+  end
+
+  # Sets header <tt>'Authorization'</tt> using the given
+  # +account+ and +password+ strings:
+  #
+  #   req.basic_auth('my_account', 'my_password')
+  #   req['Authorization']
+  #   # => "Basic bXlfYWNjb3VudDpteV9wYXNzd29yZA=="
+  #
+  def basic_auth(account, password)
+    @header['authorization'] = [basic_encode(account, password)]
+  end
+
+  # Sets header <tt>'Proxy-Authorization'</tt> using the given
+  # +account+ and +password+ strings:
+  #
+  #   req.proxy_basic_auth('my_account', 'my_password')
+  #   req['Proxy-Authorization']
+  #   # => "Basic bXlfYWNjb3VudDpteV9wYXNzd29yZA=="
+  #
+  def proxy_basic_auth(account, password)
+    @header['proxy-authorization'] = [basic_encode(account, password)]
+  end
+
+  def basic_encode(account, password)   # :nodoc:
+    'Basic ' + ["#{account}:#{password}"].pack('m0')
+  end
+  private :basic_encode
+
+  # Returns whether the HTTP session is to be closed.
+  def connection_close?
+    token = /(?:\A|,)\s*close\s*(?:\z|,)/i
+    @header['connection']&.grep(token) {return true}
+    @header['proxy-connection']&.grep(token) {return true}
+    false
+  end
+
+  # Returns whether the HTTP session is to be kept alive.
+  def connection_keep_alive?
+    token = /(?:\A|,)\s*keep-alive\s*(?:\z|,)/i
+    @header['connection']&.grep(token) {return true}
+    @header['proxy-connection']&.grep(token) {return true}
+    false
+  end
+
+end
diff --git a/lib/net/http/net-http.gemspec b/lib/net/http/net-http.gemspec
new file mode 100644
index 0000000000..d59d5c3b74
--- /dev/null
+++ b/lib/net/http/net-http.gemspec
@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+name = File.basename(__FILE__, ".gemspec")
+version = ["lib", Array.new(name.count("-")+1, "..").join("/")].find do |dir|
+  file = File.join(__dir__, dir, "#{name.tr('-', '/')}.rb")
+  begin
+    break File.foreach(file, mode: "rb") do |line|
+      /^\s*VERSION\s*=\s*"(.*)"/ =~ line and break $1
+    end
+  rescue SystemCallError
+    next
+  end
+end
+
+Gem::Specification.new do |spec|
+  spec.name          = name
+  spec.version       = version
+  spec.authors       = ["NARUSE, Yui"]
+  spec.email         = ["naruse@airemix.jp"]
+
+  spec.summary       = %q{HTTP client api for Ruby.}
+  spec.description   = %q{HTTP client api for Ruby.}
+  spec.homepage      = "https://github.com/ruby/net-http"
+  spec.required_ruby_version = Gem::Requirement.new(">= 2.7.0")
+  spec.licenses      = ["Ruby", "BSD-2-Clause"]
+
+  spec.metadata["changelog_uri"] = spec.homepage + "/releases"
+  spec.metadata["homepage_uri"] = spec.homepage
+  spec.metadata["source_code_uri"] = spec.homepage
+
+  # Specify which files should be added to the gem when it is released.
+  # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
+  excludes = %W[/.git* /bin /test /test_sig /*file /#{File.basename(__FILE__)}]
+  spec.files = IO.popen(%W[git -C #{__dir__} ls-files -z --] + excludes.map {|e| ":^#{e}"}, &:read).split("\x0")
+  spec.bindir        = "exe"
+  spec.require_paths = ["lib"]
+
+  spec.add_dependency "uri", ">= 0.11.1"
+end
diff --git a/lib/net/http/proxy_delta.rb b/lib/net/http/proxy_delta.rb
new file mode 100644
index 0000000000..e7d30def64
--- /dev/null
+++ b/lib/net/http/proxy_delta.rb
@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+module Net::HTTP::ProxyDelta   #:nodoc: internal use only
+  private
+
+  def conn_address
+    proxy_address()
+  end
+
+  def conn_port
+    proxy_port()
+  end
+
+  def edit_path(path)
+    use_ssl? ? path : "http://#{addr_port()}#{path}"
+  end
+end
+
diff --git a/lib/net/http/request.rb b/lib/net/http/request.rb
new file mode 100644
index 0000000000..4a138572e9
--- /dev/null
+++ b/lib/net/http/request.rb
@@ -0,0 +1,88 @@
+# frozen_string_literal: true
+
+# This class is the base class for \Net::HTTP request classes.
+# The class should not be used directly;
+# instead you should use its subclasses, listed below.
+#
+# == Creating a Request
+#
+# An request object may be created with either a URI or a string hostname:
+#
+#   require 'net/http'
+#   uri = URI('https://jsonplaceholder.typicode.com/')
+#   req = Net::HTTP::Get.new(uri)          # => #<Net::HTTP::Get GET>
+#   req = Net::HTTP::Get.new(uri.hostname) # => #<Net::HTTP::Get GET>
+#
+# And with any of the subclasses:
+#
+#   req = Net::HTTP::Head.new(uri) # => #<Net::HTTP::Head HEAD>
+#   req = Net::HTTP::Post.new(uri) # => #<Net::HTTP::Post POST>
+#   req = Net::HTTP::Put.new(uri)  # => #<Net::HTTP::Put PUT>
+#   # ...
+#
+# The new instance is suitable for use as the argument to Net::HTTP#request.
+#
+# == Request Headers
+#
+# A new request object has these header fields by default:
+#
+#   req.to_hash
+#   # =>
+#   {"accept-encoding"=>["gzip;q=1.0,deflate;q=0.6,identity;q=0.3"],
+#   "accept"=>["*/*"],
+#   "user-agent"=>["Ruby"],
+#   "host"=>["jsonplaceholder.typicode.com"]}
+#
+# See:
+#
+# - {Request header Accept-Encoding}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#Accept-Encoding]
+#   and {Compression and Decompression}[rdoc-ref:Net::HTTP@Compression+and+Decompression].
+# - {Request header Accept}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#accept-request-header].
+# - {Request header User-Agent}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#user-agent-request-header].
+# - {Request header Host}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#host-request-header].
+#
+# You can add headers or override default headers:
+#
+#   #   res = Net::HTTP::Get.new(uri, {'foo' => '0', 'bar' => '1'})
+#
+# This class (and therefore its subclasses) also includes (indirectly)
+# module Net::HTTPHeader, which gives access to its
+# {methods for setting headers}[rdoc-ref:Net::HTTPHeader@Setters].
+#
+# == Request Subclasses
+#
+# Subclasses for HTTP requests:
+#
+# - Net::HTTP::Get
+# - Net::HTTP::Head
+# - Net::HTTP::Post
+# - Net::HTTP::Put
+# - Net::HTTP::Delete
+# - Net::HTTP::Options
+# - Net::HTTP::Trace
+# - Net::HTTP::Patch
+#
+# Subclasses for WebDAV requests:
+#
+# - Net::HTTP::Propfind
+# - Net::HTTP::Proppatch
+# - Net::HTTP::Mkcol
+# - Net::HTTP::Copy
+# - Net::HTTP::Move
+# - Net::HTTP::Lock
+# - Net::HTTP::Unlock
+#
+class Net::HTTPRequest < Net::HTTPGenericRequest
+  # Creates an HTTP request object for +path+.
+  #
+  # +initheader+ are the default headers to use.  Net::HTTP adds
+  # Accept-Encoding to enable compression of the response body unless
+  # Accept-Encoding or Range are supplied in +initheader+.
+
+  def initialize(path, initheader = nil)
+    super self.class::METHOD,
+          self.class::REQUEST_HAS_BODY,
+          self.class::RESPONSE_HAS_BODY,
+          path, initheader
+  end
+end
diff --git a/lib/net/http/requests.rb b/lib/net/http/requests.rb
new file mode 100644
index 0000000000..8dc79a9f66
--- /dev/null
+++ b/lib/net/http/requests.rb
@@ -0,0 +1,444 @@
+# frozen_string_literal: true
+
+# HTTP/1.1 methods --- RFC2616
+
+# \Class for representing
+# {HTTP method GET}[https://en.wikipedia.org/w/index.php?title=Hypertext_Transfer_Protocol#GET_method]:
+#
+#   require 'net/http'
+#   uri = URI('http://example.com')
+#   hostname = uri.hostname # => "example.com"
+#   req = Net::HTTP::Get.new(uri) # => #<Net::HTTP::Get GET>
+#   res = Net::HTTP.start(hostname) do |http|
+#     http.request(req)
+#   end
+#
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
+# Properties:
+#
+# - Request body: optional.
+# - Response body: yes.
+# - {Safe}[https://en.wikipedia.org/wiki/HTTP#Safe_method]: yes.
+# - {Idempotent}[https://en.wikipedia.org/wiki/HTTP#Idempotent_method]: yes.
+# - {Cacheable}[https://en.wikipedia.org/wiki/HTTP#Cacheable_method]: yes.
+#
+# Related:
+#
+# - Net::HTTP.get: sends +GET+ request, returns response body.
+# - Net::HTTP#get: sends +GET+ request, returns response object.
+#
+class Net::HTTP::Get < Net::HTTPRequest
+  # :stopdoc:
+  METHOD = 'GET'
+  REQUEST_HAS_BODY  = false
+  RESPONSE_HAS_BODY = true
+end
+
+# \Class for representing
+# {HTTP method HEAD}[https://en.wikipedia.org/w/index.php?title=Hypertext_Transfer_Protocol#HEAD_method]:
+#
+#   require 'net/http'
+#   uri = URI('http://example.com')
+#   hostname = uri.hostname # => "example.com"
+#   req = Net::HTTP::Head.new(uri) # => #<Net::HTTP::Head HEAD>
+#   res = Net::HTTP.start(hostname) do |http|
+#     http.request(req)
+#   end
+#
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
+# Properties:
+#
+# - Request body: optional.
+# - Response body: no.
+# - {Safe}[https://en.wikipedia.org/wiki/HTTP#Safe_method]: yes.
+# - {Idempotent}[https://en.wikipedia.org/wiki/HTTP#Idempotent_method]: yes.
+# - {Cacheable}[https://en.wikipedia.org/wiki/HTTP#Cacheable_method]: yes.
+#
+# Related:
+#
+# - Net::HTTP#head: sends +HEAD+ request, returns response object.
+#
+class Net::HTTP::Head < Net::HTTPRequest
+  # :stopdoc:
+  METHOD = 'HEAD'
+  REQUEST_HAS_BODY = false
+  RESPONSE_HAS_BODY = false
+end
+
+# \Class for representing
+# {HTTP method POST}[https://en.wikipedia.org/w/index.php?title=Hypertext_Transfer_Protocol#POST_method]:
+#
+#   require 'net/http'
+#   uri = URI('http://example.com')
+#   hostname = uri.hostname # => "example.com"
+#   uri.path = '/posts'
+#   req = Net::HTTP::Post.new(uri) # => #<Net::HTTP::Post POST>
+#   req.body = '{"title": "foo","body": "bar","userId": 1}'
+#   req.content_type = 'application/json'
+#   res = Net::HTTP.start(hostname) do |http|
+#     http.request(req)
+#   end
+#
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
+# Properties:
+#
+# - Request body: yes.
+# - Response body: yes.
+# - {Safe}[https://en.wikipedia.org/wiki/HTTP#Safe_method]: no.
+# - {Idempotent}[https://en.wikipedia.org/wiki/HTTP#Idempotent_method]: no.
+# - {Cacheable}[https://en.wikipedia.org/wiki/HTTP#Cacheable_method]: yes.
+#
+# Related:
+#
+# - Net::HTTP.post: sends +POST+ request, returns response object.
+# - Net::HTTP#post: sends +POST+ request, returns response object.
+#
+class Net::HTTP::Post < Net::HTTPRequest
+  # :stopdoc:
+  METHOD = 'POST'
+  REQUEST_HAS_BODY = true
+  RESPONSE_HAS_BODY = true
+end
+
+# \Class for representing
+# {HTTP method PUT}[https://en.wikipedia.org/w/index.php?title=Hypertext_Transfer_Protocol#PUT_method]:
+#
+#   require 'net/http'
+#   uri = URI('http://example.com')
+#   hostname = uri.hostname # => "example.com"
+#   uri.path = '/posts'
+#   req = Net::HTTP::Put.new(uri) # => #<Net::HTTP::Put PUT>
+#   req.body = '{"title": "foo","body": "bar","userId": 1}'
+#   req.content_type = 'application/json'
+#   res = Net::HTTP.start(hostname) do |http|
+#     http.request(req)
+#   end
+#
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
+# Properties:
+#
+# - Request body: yes.
+# - Response body: yes.
+# - {Safe}[https://en.wikipedia.org/wiki/HTTP#Safe_method]: no.
+# - {Idempotent}[https://en.wikipedia.org/wiki/HTTP#Idempotent_method]: yes.
+# - {Cacheable}[https://en.wikipedia.org/wiki/HTTP#Cacheable_method]: no.
+#
+# Related:
+#
+# - Net::HTTP.put: sends +PUT+ request, returns response object.
+# - Net::HTTP#put: sends +PUT+ request, returns response object.
+#
+class Net::HTTP::Put < Net::HTTPRequest
+  # :stopdoc:
+  METHOD = 'PUT'
+  REQUEST_HAS_BODY = true
+  RESPONSE_HAS_BODY = true
+end
+
+# \Class for representing
+# {HTTP method DELETE}[https://en.wikipedia.org/w/index.php?title=Hypertext_Transfer_Protocol#DELETE_method]:
+#
+#   require 'net/http'
+#   uri = URI('http://example.com')
+#   hostname = uri.hostname # => "example.com"
+#   uri.path = '/posts/1'
+#   req = Net::HTTP::Delete.new(uri) # => #<Net::HTTP::Delete DELETE>
+#   res = Net::HTTP.start(hostname) do |http|
+#     http.request(req)
+#   end
+#
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
+# Properties:
+#
+# - Request body: optional.
+# - Response body: yes.
+# - {Safe}[https://en.wikipedia.org/wiki/HTTP#Safe_method]: no.
+# - {Idempotent}[https://en.wikipedia.org/wiki/HTTP#Idempotent_method]: yes.
+# - {Cacheable}[https://en.wikipedia.org/wiki/HTTP#Cacheable_method]: no.
+#
+# Related:
+#
+# - Net::HTTP#delete: sends +DELETE+ request, returns response object.
+#
+class Net::HTTP::Delete < Net::HTTPRequest
+  # :stopdoc:
+  METHOD = 'DELETE'
+  REQUEST_HAS_BODY = false
+  RESPONSE_HAS_BODY = true
+end
+
+# \Class for representing
+# {HTTP method OPTIONS}[https://en.wikipedia.org/w/index.php?title=Hypertext_Transfer_Protocol#OPTIONS_method]:
+#
+#   require 'net/http'
+#   uri = URI('http://example.com')
+#   hostname = uri.hostname # => "example.com"
+#   req = Net::HTTP::Options.new(uri) # => #<Net::HTTP::Options OPTIONS>
+#   res = Net::HTTP.start(hostname) do |http|
+#     http.request(req)
+#   end
+#
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
+# Properties:
+#
+# - Request body: optional.
+# - Response body: yes.
+# - {Safe}[https://en.wikipedia.org/wiki/HTTP#Safe_method]: yes.
+# - {Idempotent}[https://en.wikipedia.org/wiki/HTTP#Idempotent_method]: yes.
+# - {Cacheable}[https://en.wikipedia.org/wiki/HTTP#Cacheable_method]: no.
+#
+# Related:
+#
+# - Net::HTTP#options: sends +OPTIONS+ request, returns response object.
+#
+class Net::HTTP::Options < Net::HTTPRequest
+  # :stopdoc:
+  METHOD = 'OPTIONS'
+  REQUEST_HAS_BODY = false
+  RESPONSE_HAS_BODY = true
+end
+
+# \Class for representing
+# {HTTP method TRACE}[https://en.wikipedia.org/w/index.php?title=Hypertext_Transfer_Protocol#TRACE_method]:
+#
+#   require 'net/http'
+#   uri = URI('http://example.com')
+#   hostname = uri.hostname # => "example.com"
+#   req = Net::HTTP::Trace.new(uri) # => #<Net::HTTP::Trace TRACE>
+#   res = Net::HTTP.start(hostname) do |http|
+#     http.request(req)
+#   end
+#
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
+# Properties:
+#
+# - Request body: no.
+# - Response body: yes.
+# - {Safe}[https://en.wikipedia.org/wiki/HTTP#Safe_method]: yes.
+# - {Idempotent}[https://en.wikipedia.org/wiki/HTTP#Idempotent_method]: yes.
+# - {Cacheable}[https://en.wikipedia.org/wiki/HTTP#Cacheable_method]: no.
+#
+# Related:
+#
+# - Net::HTTP#trace: sends +TRACE+ request, returns response object.
+#
+class Net::HTTP::Trace < Net::HTTPRequest
+  # :stopdoc:
+  METHOD = 'TRACE'
+  REQUEST_HAS_BODY = false
+  RESPONSE_HAS_BODY = true
+end
+
+# \Class for representing
+# {HTTP method PATCH}[https://en.wikipedia.org/w/index.php?title=Hypertext_Transfer_Protocol#PATCH_method]:
+#
+#   require 'net/http'
+#   uri = URI('http://example.com')
+#   hostname = uri.hostname # => "example.com"
+#   uri.path = '/posts'
+#   req = Net::HTTP::Patch.new(uri) # => #<Net::HTTP::Patch PATCH>
+#   req.body = '{"title": "foo","body": "bar","userId": 1}'
+#   req.content_type = 'application/json'
+#   res = Net::HTTP.start(hostname) do |http|
+#     http.request(req)
+#   end
+#
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
+# Properties:
+#
+# - Request body: yes.
+# - Response body: yes.
+# - {Safe}[https://en.wikipedia.org/wiki/HTTP#Safe_method]: no.
+# - {Idempotent}[https://en.wikipedia.org/wiki/HTTP#Idempotent_method]: no.
+# - {Cacheable}[https://en.wikipedia.org/wiki/HTTP#Cacheable_method]: no.
+#
+# Related:
+#
+# - Net::HTTP#patch: sends +PATCH+ request, returns response object.
+#
+class Net::HTTP::Patch < Net::HTTPRequest
+  # :stopdoc:
+  METHOD = 'PATCH'
+  REQUEST_HAS_BODY = true
+  RESPONSE_HAS_BODY = true
+end
+
+#
+# WebDAV methods --- RFC2518
+#
+
+# \Class for representing
+# {WebDAV method PROPFIND}[http://www.webdav.org/specs/rfc4918.html#METHOD_PROPFIND]:
+#
+#   require 'net/http'
+#   uri = URI('http://example.com')
+#   hostname = uri.hostname # => "example.com"
+#   req = Net::HTTP::Propfind.new(uri) # => #<Net::HTTP::Propfind PROPFIND>
+#   res = Net::HTTP.start(hostname) do |http|
+#     http.request(req)
+#   end
+#
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
+# Related:
+#
+# - Net::HTTP#propfind: sends +PROPFIND+ request, returns response object.
+#
+class Net::HTTP::Propfind < Net::HTTPRequest
+  # :stopdoc:
+  METHOD = 'PROPFIND'
+  REQUEST_HAS_BODY = true
+  RESPONSE_HAS_BODY = true
+end
+
+# \Class for representing
+# {WebDAV method PROPPATCH}[http://www.webdav.org/specs/rfc4918.html#METHOD_PROPPATCH]:
+#
+#   require 'net/http'
+#   uri = URI('http://example.com')
+#   hostname = uri.hostname # => "example.com"
+#   req = Net::HTTP::Proppatch.new(uri) # => #<Net::HTTP::Proppatch PROPPATCH>
+#   res = Net::HTTP.start(hostname) do |http|
+#     http.request(req)
+#   end
+#
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
+# Related:
+#
+# - Net::HTTP#proppatch: sends +PROPPATCH+ request, returns response object.
+#
+class Net::HTTP::Proppatch < Net::HTTPRequest
+  # :stopdoc:
+  METHOD = 'PROPPATCH'
+  REQUEST_HAS_BODY = true
+  RESPONSE_HAS_BODY = true
+end
+
+# \Class for representing
+# {WebDAV method MKCOL}[http://www.webdav.org/specs/rfc4918.html#METHOD_MKCOL]:
+#
+#   require 'net/http'
+#   uri = URI('http://example.com')
+#   hostname = uri.hostname # => "example.com"
+#   req = Net::HTTP::Mkcol.new(uri) # => #<Net::HTTP::Mkcol MKCOL>
+#   res = Net::HTTP.start(hostname) do |http|
+#     http.request(req)
+#   end
+#
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
+# Related:
+#
+# - Net::HTTP#mkcol: sends +MKCOL+ request, returns response object.
+#
+class Net::HTTP::Mkcol < Net::HTTPRequest
+  # :stopdoc:
+  METHOD = 'MKCOL'
+  REQUEST_HAS_BODY = true
+  RESPONSE_HAS_BODY = true
+end
+
+# \Class for representing
+# {WebDAV method COPY}[http://www.webdav.org/specs/rfc4918.html#METHOD_COPY]:
+#
+#   require 'net/http'
+#   uri = URI('http://example.com')
+#   hostname = uri.hostname # => "example.com"
+#   req = Net::HTTP::Copy.new(uri) # => #<Net::HTTP::Copy COPY>
+#   res = Net::HTTP.start(hostname) do |http|
+#     http.request(req)
+#   end
+#
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
+# Related:
+#
+# - Net::HTTP#copy: sends +COPY+ request, returns response object.
+#
+class Net::HTTP::Copy < Net::HTTPRequest
+  # :stopdoc:
+  METHOD = 'COPY'
+  REQUEST_HAS_BODY = false
+  RESPONSE_HAS_BODY = true
+end
+
+# \Class for representing
+# {WebDAV method MOVE}[http://www.webdav.org/specs/rfc4918.html#METHOD_MOVE]:
+#
+#   require 'net/http'
+#   uri = URI('http://example.com')
+#   hostname = uri.hostname # => "example.com"
+#   req = Net::HTTP::Move.new(uri) # => #<Net::HTTP::Move MOVE>
+#   res = Net::HTTP.start(hostname) do |http|
+#     http.request(req)
+#   end
+#
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
+# Related:
+#
+# - Net::HTTP#move: sends +MOVE+ request, returns response object.
+#
+class Net::HTTP::Move < Net::HTTPRequest
+  # :stopdoc:
+  METHOD = 'MOVE'
+  REQUEST_HAS_BODY = false
+  RESPONSE_HAS_BODY = true
+end
+
+# \Class for representing
+# {WebDAV method LOCK}[http://www.webdav.org/specs/rfc4918.html#METHOD_LOCK]:
+#
+#   require 'net/http'
+#   uri = URI('http://example.com')
+#   hostname = uri.hostname # => "example.com"
+#   req = Net::HTTP::Lock.new(uri) # => #<Net::HTTP::Lock LOCK>
+#   res = Net::HTTP.start(hostname) do |http|
+#     http.request(req)
+#   end
+#
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
+# Related:
+#
+# - Net::HTTP#lock: sends +LOCK+ request, returns response object.
+#
+class Net::HTTP::Lock < Net::HTTPRequest
+  # :stopdoc:
+  METHOD = 'LOCK'
+  REQUEST_HAS_BODY = true
+  RESPONSE_HAS_BODY = true
+end
+
+# \Class for representing
+# {WebDAV method UNLOCK}[http://www.webdav.org/specs/rfc4918.html#METHOD_UNLOCK]:
+#
+#   require 'net/http'
+#   uri = URI('http://example.com')
+#   hostname = uri.hostname # => "example.com"
+#   req = Net::HTTP::Unlock.new(uri) # => #<Net::HTTP::Unlock UNLOCK>
+#   res = Net::HTTP.start(hostname) do |http|
+#     http.request(req)
+#   end
+#
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
+# Related:
+#
+# - Net::HTTP#unlock: sends +UNLOCK+ request, returns response object.
+#
+class Net::HTTP::Unlock < Net::HTTPRequest
+  # :stopdoc:
+  METHOD = 'UNLOCK'
+  REQUEST_HAS_BODY = true
+  RESPONSE_HAS_BODY = true
+end
diff --git a/lib/net/http/response.rb b/lib/net/http/response.rb
new file mode 100644
index 0000000000..8804a99c9e
--- /dev/null
+++ b/lib/net/http/response.rb
@@ -0,0 +1,739 @@
+# frozen_string_literal: true
+
+# This class is the base class for \Net::HTTP response classes.
+#
+# == About the Examples
+#
+# :include: doc/net-http/examples.rdoc
+#
+# == Returned Responses
+#
+# \Method Net::HTTP.get_response returns
+# an instance of one of the subclasses of \Net::HTTPResponse:
+#
+#   Net::HTTP.get_response(uri)
+#   # => #<Net::HTTPOK 200 OK readbody=true>
+#   Net::HTTP.get_response(hostname, '/nosuch')
+#   # => #<Net::HTTPNotFound 404 Not Found readbody=true>
+#
+# As does method Net::HTTP#request:
+#
+#   req = Net::HTTP::Get.new(uri)
+#   Net::HTTP.start(hostname) do |http|
+#     http.request(req)
+#   end # => #<Net::HTTPOK 200 OK readbody=true>
+#
+# \Class \Net::HTTPResponse includes module Net::HTTPHeader,
+# which provides access to response header values via (among others):
+#
+# - \Hash-like method <tt>[]</tt>.
+# - Specific reader methods, such as +content_type+.
+#
+# Examples:
+#
+#   res = Net::HTTP.get_response(uri) # => #<Net::HTTPOK 200 OK readbody=true>
+#   res['Content-Type']               # => "text/html; charset=UTF-8"
+#   res.content_type                  # => "text/html"
+#
+# == Response Subclasses
+#
+# \Class \Net::HTTPResponse has a subclass for each
+# {HTTP status code}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes].
+# You can look up the response class for a given code:
+#
+#   Net::HTTPResponse::CODE_TO_OBJ['200'] # => Net::HTTPOK
+#   Net::HTTPResponse::CODE_TO_OBJ['400'] # => Net::HTTPBadRequest
+#   Net::HTTPResponse::CODE_TO_OBJ['404'] # => Net::HTTPNotFound
+#
+# And you can retrieve the status code for a response object:
+#
+#   Net::HTTP.get_response(uri).code                 # => "200"
+#   Net::HTTP.get_response(hostname, '/nosuch').code # => "404"
+#
+# The response subclasses (indentation shows class hierarchy):
+#
+# - Net::HTTPUnknownResponse (for unhandled \HTTP extensions).
+#
+# - Net::HTTPInformation:
+#
+#   - Net::HTTPContinue (100)
+#   - Net::HTTPSwitchProtocol (101)
+#   - Net::HTTPProcessing (102)
+#   - Net::HTTPEarlyHints (103)
+#
+# - Net::HTTPSuccess:
+#
+#   - Net::HTTPOK (200)
+#   - Net::HTTPCreated (201)
+#   - Net::HTTPAccepted (202)
+#   - Net::HTTPNonAuthoritativeInformation (203)
+#   - Net::HTTPNoContent (204)
+#   - Net::HTTPResetContent (205)
+#   - Net::HTTPPartialContent (206)
+#   - Net::HTTPMultiStatus (207)
+#   - Net::HTTPAlreadyReported (208)
+#   - Net::HTTPIMUsed (226)
+#
+# - Net::HTTPRedirection:
+#
+#   - Net::HTTPMultipleChoices (300)
+#   - Net::HTTPMovedPermanently (301)
+#   - Net::HTTPFound (302)
+#   - Net::HTTPSeeOther (303)
+#   - Net::HTTPNotModified (304)
+#   - Net::HTTPUseProxy (305)
+#   - Net::HTTPTemporaryRedirect (307)
+#   - Net::HTTPPermanentRedirect (308)
+#
+# - Net::HTTPClientError:
+#
+#   - Net::HTTPBadRequest (400)
+#   - Net::HTTPUnauthorized (401)
+#   - Net::HTTPPaymentRequired (402)
+#   - Net::HTTPForbidden (403)
+#   - Net::HTTPNotFound (404)
+#   - Net::HTTPMethodNotAllowed (405)
+#   - Net::HTTPNotAcceptable (406)
+#   - Net::HTTPProxyAuthenticationRequired (407)
+#   - Net::HTTPRequestTimeOut (408)
+#   - Net::HTTPConflict (409)
+#   - Net::HTTPGone (410)
+#   - Net::HTTPLengthRequired (411)
+#   - Net::HTTPPreconditionFailed (412)
+#   - Net::HTTPRequestEntityTooLarge (413)
+#   - Net::HTTPRequestURITooLong (414)
+#   - Net::HTTPUnsupportedMediaType (415)
+#   - Net::HTTPRequestedRangeNotSatisfiable (416)
+#   - Net::HTTPExpectationFailed (417)
+#   - Net::HTTPMisdirectedRequest (421)
+#   - Net::HTTPUnprocessableEntity (422)
+#   - Net::HTTPLocked (423)
+#   - Net::HTTPFailedDependency (424)
+#   - Net::HTTPUpgradeRequired (426)
+#   - Net::HTTPPreconditionRequired (428)
+#   - Net::HTTPTooManyRequests (429)
+#   - Net::HTTPRequestHeaderFieldsTooLarge (431)
+#   - Net::HTTPUnavailableForLegalReasons (451)
+#
+# - Net::HTTPServerError:
+#
+#   - Net::HTTPInternalServerError (500)
+#   - Net::HTTPNotImplemented (501)
+#   - Net::HTTPBadGateway (502)
+#   - Net::HTTPServiceUnavailable (503)
+#   - Net::HTTPGatewayTimeOut (504)
+#   - Net::HTTPVersionNotSupported (505)
+#   - Net::HTTPVariantAlsoNegotiates (506)
+#   - Net::HTTPInsufficientStorage (507)
+#   - Net::HTTPLoopDetected (508)
+#   - Net::HTTPNotExtended (510)
+#   - Net::HTTPNetworkAuthenticationRequired (511)
+#
+# There is also the Net::HTTPBadResponse exception which is raised when
+# there is a protocol error.
+#
+class Net::HTTPResponse
+  class << self
+    # true if the response has a body.
+    def body_permitted?
+      self::HAS_BODY
+    end
+
+    def exception_type   # :nodoc: internal use only
+      self::EXCEPTION_TYPE
+    end
+
+    def read_new(sock)   #:nodoc: internal use only
+      httpv, code, msg = read_status_line(sock)
+      res = response_class(code).new(httpv, code, msg)
+      each_response_header(sock) do |k,v|
+        res.add_field k, v
+      end
+      res
+    end
+
+    private
+    # :stopdoc:
+
+    def read_status_line(sock)
+      str = sock.readline
+      m = /\AHTTP(?:\/(\d+\.\d+))?\s+(\d\d\d)(?:\s+(.*))?\z/in.match(str) or
+        raise Net::HTTPBadResponse, "wrong status line: #{str.dump}"
+      m.captures
+    end
+
+    def response_class(code)
+      CODE_TO_OBJ[code] or
+      CODE_CLASS_TO_OBJ[code[0,1]] or
+      Net::HTTPUnknownResponse
+    end
+
+    def each_response_header(sock)
+      key = value = nil
+      while true
+        line = sock.readuntil("\n", true).sub(/\s+\z/, '')
+        break if line.empty?
+        if line[0] == ?\s or line[0] == ?\t and value
+          value << ' ' unless value.empty?
+          value << line.strip
+        else
+          yield key, value if key
+          key, value = line.strip.split(/\s*:\s*/, 2)
+          raise Net::HTTPBadResponse, 'wrong header line format' if value.nil?
+        end
+      end
+      yield key, value if key
+    end
+  end
+
+  # next is to fix bug in RDoc, where the private inside class << self
+  # spills out.
+  public
+
+  include Net::HTTPHeader
+
+  def initialize(httpv, code, msg)   #:nodoc: internal use only
+    @http_version = httpv
+    @code         = code
+    @message      = msg
+    initialize_http_header nil
+    @body = nil
+    @read = false
+    @uri  = nil
+    @decode_content = false
+    @body_encoding = false
+    @ignore_eof = true
+  end
+
+  # The HTTP version supported by the server.
+  attr_reader :http_version
+
+  # The HTTP result code string. For example, '302'.  You can also
+  # determine the response type by examining which response subclass
+  # the response object is an instance of.
+  attr_reader :code
+
+  # The HTTP result message sent by the server. For example, 'Not Found'.
+  attr_reader :message
+  alias msg message   # :nodoc: obsolete
+
+  # The URI used to fetch this response.  The response URI is only available
+  # if a URI was used to create the request.
+  attr_reader :uri
+
+  # Set to true automatically when the request did not contain an
+  # Accept-Encoding header from the user.
+  attr_accessor :decode_content
+
+  # Returns the value set by body_encoding=, or +false+ if none;
+  # see #body_encoding=.
+  attr_reader :body_encoding
+
+  # Sets the encoding that should be used when reading the body:
+  #
+  # - If the given value is an Encoding object, that encoding will be used.
+  # - Otherwise if the value is a string, the value of
+  #   {Encoding#find(value)}[rdoc-ref:Encoding.find]
+  #   will be used.
+  # - Otherwise an encoding will be deduced from the body itself.
+  #
+  # Examples:
+  #
+  #   http = Net::HTTP.new(hostname)
+  #   req = Net::HTTP::Get.new('/')
+  #
+  #   http.request(req) do |res|
+  #     p res.body.encoding # => #<Encoding:ASCII-8BIT>
+  #   end
+  #
+  #   http.request(req) do |res|
+  #     res.body_encoding = "UTF-8"
+  #     p res.body.encoding # => #<Encoding:UTF-8>
+  #   end
+  #
+  def body_encoding=(value)
+    value = Encoding.find(value) if value.is_a?(String)
+    @body_encoding = value
+  end
+
+  # Whether to ignore EOF when reading bodies with a specified Content-Length
+  # header.
+  attr_accessor :ignore_eof
+
+  def inspect   # :nodoc:
+    "#<#{self.class} #{@code} #{@message} readbody=#{@read}>"
+  end
+
+  #
+  # response <-> exception relationship
+  #
+
+  def code_type   #:nodoc:
+    self.class
+  end
+
+  def error!   #:nodoc:
+    message = @code
+    message = "#{message} #{@message.dump}" if @message
+    raise error_type().new(message, self)
+  end
+
+  def error_type   #:nodoc:
+    self.class::EXCEPTION_TYPE
+  end
+
+  # Raises an HTTP error if the response is not 2xx (success).
+  def value
+    error! unless self.kind_of?(Net::HTTPSuccess)
+  end
+
+  def uri= uri # :nodoc:
+    @uri = uri.dup if uri
+  end
+
+  #
+  # header (for backward compatibility only; DO NOT USE)
+  #
+
+  def response   #:nodoc:
+    warn "Net::HTTPResponse#response is obsolete", uplevel: 1 if $VERBOSE
+    self
+  end
+
+  def header   #:nodoc:
+    warn "Net::HTTPResponse#header is obsolete", uplevel: 1 if $VERBOSE
+    self
+  end
+
+  def read_header   #:nodoc:
+    warn "Net::HTTPResponse#read_header is obsolete", uplevel: 1 if $VERBOSE
+    self
+  end
+
+  #
+  # body
+  #
+
+  def reading_body(sock, reqmethodallowbody)  #:nodoc: internal use only
+    @socket = sock
+    @body_exist = reqmethodallowbody && self.class.body_permitted?
+    begin
+      yield
+      self.body   # ensure to read body
+    ensure
+      @socket = nil
+    end
+  end
+
+  # Gets the entity body returned by the remote HTTP server.
+  #
+  # If a block is given, the body is passed to the block, and
+  # the body is provided in fragments, as it is read in from the socket.
+  #
+  # If +dest+ argument is given, response is read into that variable,
+  # with <code>dest#<<</code> method (it could be String or IO, or any
+  # other object responding to <code><<</code>).
+  #
+  # Calling this method a second or subsequent time for the same
+  # HTTPResponse object will return the value already read.
+  #
+  #   http.request_get('/index.html') {|res|
+  #     puts res.read_body
+  #   }
+  #
+  #   http.request_get('/index.html') {|res|
+  #     p res.read_body.object_id   # 538149362
+  #     p res.read_body.object_id   # 538149362
+  #   }
+  #
+  #   # using iterator
+  #   http.request_get('/index.html') {|res|
+  #     res.read_body do |segment|
+  #       print segment
+  #     end
+  #   }
+  #
+  def read_body(dest = nil, &block)
+    if @read
+      raise IOError, "#{self.class}\#read_body called twice" if dest or block
+      return @body
+    end
+    to = procdest(dest, block)
+    stream_check
+    if @body_exist
+      read_body_0 to
+      @body = to
+    else
+      @body = nil
+    end
+    @read = true
+    return if @body.nil?
+
+    case enc = @body_encoding
+    when Encoding, false, nil
+      # Encoding: force given encoding
+      # false/nil: do not force encoding
+    else
+      # other value: detect encoding from body
+      enc = detect_encoding(@body)
+    end
+
+    @body.force_encoding(enc) if enc
+
+    @body
+  end
+
+  # Returns the string response body;
+  # note that repeated calls for the unmodified body return a cached string:
+  #
+  #   path = '/todos/1'
+  #   Net::HTTP.start(hostname) do |http|
+  #     res = http.get(path)
+  #     p res.body
+  #     p http.head(path).body # No body.
+  #   end
+  #
+  # Output:
+  #
+  #   "{\n  \"userId\": 1,\n  \"id\": 1,\n  \"title\": \"delectus aut autem\",\n  \"completed\": false\n}"
+  #   nil
+  #
+  def body
+    read_body()
+  end
+
+  # Sets the body of the response to the given value.
+  def body=(value)
+    @body = value
+  end
+
+  alias entity body   #:nodoc: obsolete
+
+  private
+
+  # :nodoc:
+  def detect_encoding(str, encoding=nil)
+    if encoding
+    elsif encoding = type_params['charset']
+    elsif encoding = check_bom(str)
+    else
+      encoding = case content_type&.downcase
+      when %r{text/x(?:ht)?ml|application/(?:[^+]+\+)?xml}
+        /\A<xml[ \t\r\n]+
+          version[ \t\r\n]*=[ \t\r\n]*(?:"[0-9.]+"|'[0-9.]*')[ \t\r\n]+
+          encoding[ \t\r\n]*=[ \t\r\n]*
+          (?:"([A-Za-z][\-A-Za-z0-9._]*)"|'([A-Za-z][\-A-Za-z0-9._]*)')/x =~ str
+        encoding = $1 || $2 || Encoding::UTF_8
+      when %r{text/html.*}
+        sniff_encoding(str)
+      end
+    end
+    return encoding
+  end
+
+  # :nodoc:
+  def sniff_encoding(str, encoding=nil)
+    # the encoding sniffing algorithm
+    # http://www.w3.org/TR/html5/parsing.html#determining-the-character-encoding
+    if enc = scanning_meta(str)
+      enc
+    # 6. last visited page or something
+    # 7. frequency
+    elsif str.ascii_only?
+      Encoding::US_ASCII
+    elsif str.dup.force_encoding(Encoding::UTF_8).valid_encoding?
+      Encoding::UTF_8
+    end
+    # 8. implementation-defined or user-specified
+  end
+
+  # :nodoc:
+  def check_bom(str)
+    case str.byteslice(0, 2)
+    when "\xFE\xFF"
+      return Encoding::UTF_16BE
+    when "\xFF\xFE"
+      return Encoding::UTF_16LE
+    end
+    if "\xEF\xBB\xBF" == str.byteslice(0, 3)
+      return Encoding::UTF_8
+    end
+    nil
+  end
+
+  # :nodoc:
+  def scanning_meta(str)
+    require 'strscan'
+    ss = StringScanner.new(str)
+    if ss.scan_until(/<meta[\t\n\f\r ]*/)
+      attrs = {} # attribute_list
+      got_pragma = false
+      need_pragma = nil
+      charset = nil
+
+      # step: Attributes
+      while attr = get_attribute(ss)
+        name, value = *attr
+        next if attrs[name]
+        attrs[name] = true
+        case name
+        when 'http-equiv'
+          got_pragma = true if value == 'content-type'
+        when 'content'
+          encoding = extracting_encodings_from_meta_elements(value)
+          unless charset
+            charset = encoding
+          end
+          need_pragma = true
+        when 'charset'
+          need_pragma = false
+          charset = value
+        end
+      end
+
+      # step: Processing
+      return if need_pragma.nil?
+      return if need_pragma && !got_pragma
+
+      charset = Encoding.find(charset) rescue nil
+      return unless charset
+      charset = Encoding::UTF_8 if charset == Encoding::UTF_16
+      return charset # tentative
+    end
+    nil
+  end
+
+  def get_attribute(ss)
+    ss.scan(/[\t\n\f\r \/]*/)
+    if ss.peek(1) == '>'
+      ss.getch
+      return nil
+    end
+    name = ss.scan(/[^=\t\n\f\r \/>]*/)
+    name.downcase!
+    raise if name.empty?
+    ss.skip(/[\t\n\f\r ]*/)
+    if ss.getch != '='
+      value = ''
+      return [name, value]
+    end
+    ss.skip(/[\t\n\f\r ]*/)
+    case ss.peek(1)
+    when '"'
+      ss.getch
+      value = ss.scan(/[^"]+/)
+      value.downcase!
+      ss.getch
+    when "'"
+      ss.getch
+      value = ss.scan(/[^']+/)
+      value.downcase!
+      ss.getch
+    when '>'
+      value = ''
+    else
+      value = ss.scan(/[^\t\n\f\r >]+/)
+      value.downcase!
+    end
+    [name, value]
+  end
+
+  def extracting_encodings_from_meta_elements(value)
+    # http://dev.w3.org/html5/spec/fetching-resources.html#algorithm-for-extracting-an-encoding-from-a-meta-element
+    if /charset[\t\n\f\r ]*=(?:"([^"]*)"|'([^']*)'|["']|\z|([^\t\n\f\r ;]+))/i =~ value
+      return $1 || $2 || $3
+    end
+    return nil
+  end
+
+  ##
+  # Checks for a supported Content-Encoding header and yields an Inflate
+  # wrapper for this response's socket when zlib is present.  If the
+  # Content-Encoding is not supported or zlib is missing, the plain socket is
+  # yielded.
+  #
+  # If a Content-Range header is present, a plain socket is yielded as the
+  # bytes in the range may not be a complete deflate block.
+
+  def inflater # :nodoc:
+    return yield @socket unless Net::HTTP::HAVE_ZLIB
+    return yield @socket unless @decode_content
+    return yield @socket if self['content-range']
+
+    v = self['content-encoding']
+    case v&.downcase
+    when 'deflate', 'gzip', 'x-gzip' then
+      self.delete 'content-encoding'
+
+      inflate_body_io = Inflater.new(@socket)
+
+      begin
+        yield inflate_body_io
+        success = true
+      ensure
+        begin
+          inflate_body_io.finish
+          if self['content-length']
+            self['content-length'] = inflate_body_io.bytes_inflated.to_s
+          end
+        rescue => err
+          # Ignore #finish's error if there is an exception from yield
+          raise err if success
+        end
+      end
+    when 'none', 'identity' then
+      self.delete 'content-encoding'
+
+      yield @socket
+    else
+      yield @socket
+    end
+  end
+
+  def read_body_0(dest)
+    inflater do |inflate_body_io|
+      if chunked?
+        read_chunked dest, inflate_body_io
+        return
+      end
+
+      @socket = inflate_body_io
+
+      clen = content_length()
+      if clen
+        @socket.read clen, dest, @ignore_eof
+        return
+      end
+      clen = range_length()
+      if clen
+        @socket.read clen, dest
+        return
+      end
+      @socket.read_all dest
+    end
+  end
+
+  ##
+  # read_chunked reads from +@socket+ for chunk-size, chunk-extension, CRLF,
+  # etc. and +chunk_data_io+ for chunk-data which may be deflate or gzip
+  # encoded.
+  #
+  # See RFC 2616 section 3.6.1 for definitions
+
+  def read_chunked(dest, chunk_data_io) # :nodoc:
+    total = 0
+    while true
+      line = @socket.readline
+      hexlen = line.slice(/[0-9a-fA-F]+/) or
+          raise Net::HTTPBadResponse, "wrong chunk size line: #{line}"
+      len = hexlen.hex
+      break if len == 0
+      begin
+        chunk_data_io.read len, dest
+      ensure
+        total += len
+        @socket.read 2   # \r\n
+      end
+    end
+    until @socket.readline.empty?
+      # none
+    end
+  end
+
+  def stream_check
+    raise IOError, 'attempt to read body out of block' if @socket.nil? || @socket.closed?
+  end
+
+  def procdest(dest, block)
+    raise ArgumentError, 'both arg and block given for HTTP method' if
+      dest and block
+    if block
+      Net::ReadAdapter.new(block)
+    else
+      dest || +''
+    end
+  end
+
+  ##
+  # Inflater is a wrapper around Net::BufferedIO that transparently inflates
+  # zlib and gzip streams.
+
+  class Inflater # :nodoc:
+
+    ##
+    # Creates a new Inflater wrapping +socket+
+
+    def initialize socket
+      @socket = socket
+      # zlib with automatic gzip detection
+      @inflate = Zlib::Inflate.new(32 + Zlib::MAX_WBITS)
+    end
+
+    ##
+    # Finishes the inflate stream.
+
+    def finish
+      return if @inflate.total_in == 0
+      @inflate.finish
+    end
+
+    ##
+    # The number of bytes inflated, used to update the Content-Length of
+    # the response.
+
+    def bytes_inflated
+      @inflate.total_out
+    end
+
+    ##
+    # Returns a Net::ReadAdapter that inflates each read chunk into +dest+.
+    #
+    # This allows a large response body to be inflated without storing the
+    # entire body in memory.
+
+    def inflate_adapter(dest)
+      if dest.respond_to?(:set_encoding)
+        dest.set_encoding(Encoding::ASCII_8BIT)
+      elsif dest.respond_to?(:force_encoding)
+        dest.force_encoding(Encoding::ASCII_8BIT)
+      end
+      block = proc do |compressed_chunk|
+        @inflate.inflate(compressed_chunk) do |chunk|
+          compressed_chunk.clear
+          dest << chunk
+        end
+      end
+
+      Net::ReadAdapter.new(block)
+    end
+
+    ##
+    # Reads +clen+ bytes from the socket, inflates them, then writes them to
+    # +dest+.  +ignore_eof+ is passed down to Net::BufferedIO#read
+    #
+    # Unlike Net::BufferedIO#read, this method returns more than +clen+ bytes.
+    # At this time there is no way for a user of Net::HTTPResponse to read a
+    # specific number of bytes from the HTTP response body, so this internal
+    # API does not return the same number of bytes as were requested.
+    #
+    # See https://bugs.ruby-lang.org/issues/6492 for further discussion.
+
+    def read clen, dest, ignore_eof = false
+      temp_dest = inflate_adapter(dest)
+
+      @socket.read clen, temp_dest, ignore_eof
+    end
+
+    ##
+    # Reads the rest of the socket, inflates it, then writes it to +dest+.
+
+    def read_all dest
+      temp_dest = inflate_adapter(dest)
+
+      @socket.read_all temp_dest
+    end
+
+  end
+
+end
+
diff --git a/lib/net/http/responses.rb b/lib/net/http/responses.rb
new file mode 100644
index 0000000000..941a6fed80
--- /dev/null
+++ b/lib/net/http/responses.rb
@@ -0,0 +1,1242 @@
+# frozen_string_literal: true
+#--
+# https://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml
+
+module Net
+
+  # Unknown HTTP response
+  class HTTPUnknownResponse < HTTPResponse
+    # :stopdoc:
+    HAS_BODY = true
+    EXCEPTION_TYPE = HTTPError                  #
+  end
+
+  # Parent class for informational (1xx) HTTP response classes.
+  #
+  # An informational response indicates that the request was received and understood.
+  #
+  # References:
+  #
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#status.1xx].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#1xx_informational_response].
+  #
+  class HTTPInformation < HTTPResponse
+    # :stopdoc:
+    HAS_BODY = false
+    EXCEPTION_TYPE = HTTPError                  #
+  end
+
+  # Parent class for success (2xx) HTTP response classes.
+  #
+  # A success response indicates the action requested by the client
+  # was received, understood, and accepted.
+  #
+  # References:
+  #
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#status.2xx].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#2xx_success].
+  #
+  class HTTPSuccess < HTTPResponse
+    # :stopdoc:
+    HAS_BODY = true
+    EXCEPTION_TYPE = HTTPError                  #
+  end
+
+  # Parent class for redirection (3xx) HTTP response classes.
+  #
+  # A redirection response indicates the client must take additional action
+  # to complete the request.
+  #
+  # References:
+  #
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#status.3xx].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#3xx_redirection].
+  #
+  class HTTPRedirection < HTTPResponse
+    # :stopdoc:
+    HAS_BODY = true
+    EXCEPTION_TYPE = HTTPRetriableError         #
+  end
+
+  # Parent class for client error (4xx) HTTP response classes.
+  #
+  # A client error response indicates that the client may have caused an error.
+  #
+  # References:
+  #
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#status.4xx].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#4xx_client_errors].
+  #
+  class HTTPClientError < HTTPResponse
+    # :stopdoc:
+    HAS_BODY = true
+    EXCEPTION_TYPE = HTTPClientException        #
+  end
+
+  # Parent class for server error (5xx) HTTP response classes.
+  #
+  # A server error response indicates that the server failed to fulfill a request.
+  #
+  # References:
+  #
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#status.5xx].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#5xx_server_errors].
+  #
+  class HTTPServerError < HTTPResponse
+    # :stopdoc:
+    HAS_BODY = true
+    EXCEPTION_TYPE = HTTPFatalError             #
+  end
+
+  # Response class for +Continue+ responses (status code 100).
+  #
+  # A +Continue+ response indicates that the server has received the request headers.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/100].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-100-continue].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#100].
+  #
+  class HTTPContinue < HTTPInformation
+    # :stopdoc:
+    HAS_BODY = false
+  end
+
+  # Response class for <tt>Switching Protocol</tt> responses (status code 101).
+  #
+  # The <tt>Switching Protocol<tt> response indicates that the server has received
+  # a request to switch protocols, and has agreed to do so.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/101].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-101-switching-protocols].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#101].
+  #
+  class HTTPSwitchProtocol < HTTPInformation
+    # :stopdoc:
+    HAS_BODY = false
+  end
+
+  # Response class for +Processing+ responses (status code 102).
+  #
+  # The +Processing+ response indicates that the server has received
+  # and is processing the request, but no response is available yet.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {RFC 2518}[https://www.rfc-editor.org/rfc/rfc2518#section-10.1].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#102].
+  #
+  class HTTPProcessing < HTTPInformation
+    # :stopdoc:
+    HAS_BODY = false
+  end
+
+  # Response class for <tt>Early Hints</tt> responses (status code 103).
+  #
+  # The <tt>Early Hints</tt> indicates that the server has received
+  # and is processing the request, and contains certain headers;
+  # the final response is not available yet.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/103].
+  # - {RFC 8297}[https://www.rfc-editor.org/rfc/rfc8297.html#section-2].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#103].
+  #
+  class HTTPEarlyHints < HTTPInformation
+    # :stopdoc:
+    HAS_BODY = false
+  end
+
+  # Response class for +OK+ responses (status code 200).
+  #
+  # The +OK+ response indicates that the server has received
+  # a request and has responded successfully.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/200].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-200-ok].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#200].
+  #
+  class HTTPOK < HTTPSuccess
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for +Created+ responses (status code 201).
+  #
+  # The +Created+ response indicates that the server has received
+  # and has fulfilled a request to create a new resource.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/201].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-201-created].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#201].
+  #
+  class HTTPCreated < HTTPSuccess
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for +Accepted+ responses (status code 202).
+  #
+  # The +Accepted+ response indicates that the server has received
+  # and is processing a request, but the processing has not yet been completed.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/202].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-202-accepted].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#202].
+  #
+  class HTTPAccepted < HTTPSuccess
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Non-Authoritative Information</tt> responses (status code 203).
+  #
+  # The <tt>Non-Authoritative Information</tt> response indicates that the server
+  # is a transforming proxy (such as a Web accelerator)
+  # that received a 200 OK response from its origin,
+  # and is returning a modified version of the origin's response.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/203].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-203-non-authoritative-infor].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#203].
+  #
+  class HTTPNonAuthoritativeInformation < HTTPSuccess
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>No Content</tt> responses (status code 204).
+  #
+  # The <tt>No Content</tt> response indicates that the server
+  # successfully processed the request, and is not returning any content.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/204].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-204-no-content].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#204].
+  #
+  class HTTPNoContent < HTTPSuccess
+    # :stopdoc:
+    HAS_BODY = false
+  end
+
+  # Response class for <tt>Reset Content</tt> responses (status code 205).
+  #
+  # The <tt>Reset Content</tt> response indicates that the server
+  # successfully processed the request,
+  # asks that the client reset its document view, and is not returning any content.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/205].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-205-reset-content].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#205].
+  #
+  class HTTPResetContent < HTTPSuccess
+    # :stopdoc:
+    HAS_BODY = false
+  end
+
+  # Response class for <tt>Partial Content</tt> responses (status code 206).
+  #
+  # The <tt>Partial Content</tt> response indicates that the server is delivering
+  # only part of the resource (byte serving)
+  # due to a Range header in the request.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/206].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-206-partial-content].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#206].
+  #
+  class HTTPPartialContent < HTTPSuccess
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Multi-Status (WebDAV)</tt> responses (status code 207).
+  #
+  # The <tt>Multi-Status (WebDAV)</tt> response indicates that the server
+  # has received the request,
+  # and that the message body can contain a number of separate response codes.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {RFC 4818}[https://www.rfc-editor.org/rfc/rfc4918#section-11.1].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#207].
+  #
+  class HTTPMultiStatus < HTTPSuccess
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Already Reported (WebDAV)</tt> responses (status code 208).
+  #
+  # The <tt>Already Reported (WebDAV)</tt> response indicates that the server
+  # has received the request,
+  # and that the members of a DAV binding have already been enumerated
+  # in a preceding part of the (multi-status) response,
+  # and are not being included again.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {RFC 5842}[https://www.rfc-editor.org/rfc/rfc5842.html#section-7.1].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#208].
+  #
+  class HTTPAlreadyReported < HTTPSuccess
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>IM Used</tt> responses (status code 226).
+  #
+  # The <tt>IM Used</tt> response indicates that the server has fulfilled a request
+  # for the resource, and the response is a representation of the result
+  # of one or more instance-manipulations applied to the current instance.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {RFC 3229}[https://www.rfc-editor.org/rfc/rfc3229.html#section-10.4.1].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#226].
+  #
+  class HTTPIMUsed < HTTPSuccess
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Multiple Choices</tt> responses (status code 300).
+  #
+  # The <tt>Multiple Choices</tt> response indicates that the server
+  # offers multiple options for the resource from which the client may choose.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/300].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-300-multiple-choices].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#300].
+  #
+  class HTTPMultipleChoices < HTTPRedirection
+    # :stopdoc:
+    HAS_BODY = true
+  end
+  HTTPMultipleChoice = HTTPMultipleChoices
+
+  # Response class for <tt>Moved Permanently</tt> responses (status code 301).
+  #
+  # The <tt>Moved Permanently</tt> response indicates that links or records
+  # returning this response should be updated to use the given URL.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/301].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-301-moved-permanently].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#301].
+  #
+  class HTTPMovedPermanently < HTTPRedirection
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Found</tt> responses (status code 302).
+  #
+  # The <tt>Found</tt> response indicates that the client
+  # should look at (browse to) another URL.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/302].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-302-found].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#302].
+  #
+  class HTTPFound < HTTPRedirection
+    # :stopdoc:
+    HAS_BODY = true
+  end
+  HTTPMovedTemporarily = HTTPFound
+
+  # Response class for <tt>See Other</tt> responses (status code 303).
+  #
+  # The response to the request can be found under another URI using the GET method.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/303].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-303-see-other].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#303].
+  #
+  class HTTPSeeOther < HTTPRedirection
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Not Modified</tt> responses (status code 304).
+  #
+  # Indicates that the resource has not been modified since the version
+  # specified by the request headers.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/304].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-304-not-modified].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#304].
+  #
+  class HTTPNotModified < HTTPRedirection
+    # :stopdoc:
+    HAS_BODY = false
+  end
+
+  # Response class for <tt>Use Proxy</tt> responses (status code 305).
+  #
+  # The requested resource is available only through a proxy,
+  # whose address is provided in the response.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-305-use-proxy].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#305].
+  #
+  class HTTPUseProxy < HTTPRedirection
+    # :stopdoc:
+    HAS_BODY = false
+  end
+
+  # Response class for <tt>Temporary Redirect</tt> responses (status code 307).
+  #
+  # The request should be repeated with another URI;
+  # however, future requests should still use the original URI.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/307].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-307-temporary-redirect].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#307].
+  #
+  class HTTPTemporaryRedirect < HTTPRedirection
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Permanent Redirect</tt> responses (status code 308).
+  #
+  # This and all future requests should be directed to the given URI.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/308].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-308-permanent-redirect].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#308].
+  #
+  class HTTPPermanentRedirect < HTTPRedirection
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Bad Request</tt> responses (status code 400).
+  #
+  # The server cannot or will not process the request due to an apparent client error.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/400].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-400-bad-request].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#400].
+  #
+  class HTTPBadRequest < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Unauthorized</tt> responses (status code 401).
+  #
+  # Authentication is required, but either was not provided or failed.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/401].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-401-unauthorized].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#401].
+  #
+  class HTTPUnauthorized < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Payment Required</tt> responses (status code 402).
+  #
+  # Reserved for future use.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/402].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-402-payment-required].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#402].
+  #
+  class HTTPPaymentRequired < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Forbidden</tt> responses (status code 403).
+  #
+  # The request contained valid data and was understood by the server,
+  # but the server is refusing action.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/403].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-403-forbidden].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#403].
+  #
+  class HTTPForbidden < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Not Found</tt> responses (status code 404).
+  #
+  # The requested resource could not be found but may be available in the future.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/404].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-404-not-found].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#404].
+  #
+  class HTTPNotFound < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Method Not Allowed</tt> responses (status code 405).
+  #
+  # The request method is not supported for the requested resource.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/405].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-405-method-not-allowed].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#405].
+  #
+  class HTTPMethodNotAllowed < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Not Acceptable</tt> responses (status code 406).
+  #
+  # The requested resource is capable of generating only content
+  # that not acceptable according to the Accept headers sent in the request.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/406].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-406-not-acceptable].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#406].
+  #
+  class HTTPNotAcceptable < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Proxy Authentication Required</tt> responses (status code 407).
+  #
+  # The client must first authenticate itself with the proxy.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/407].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-407-proxy-authentication-re].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#407].
+  #
+  class HTTPProxyAuthenticationRequired < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Request Timeout</tt> responses (status code 408).
+  #
+  # The server timed out waiting for the request.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/408].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-408-request-timeout].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#408].
+  #
+  class HTTPRequestTimeout < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+  HTTPRequestTimeOut = HTTPRequestTimeout
+
+  # Response class for <tt>Conflict</tt> responses (status code 409).
+  #
+  # The request could not be processed because of conflict in the current state of the resource.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/409].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-409-conflict].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#409].
+  #
+  class HTTPConflict < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Gone</tt> responses (status code 410).
+  #
+  # The resource requested was previously in use but is no longer available
+  # and will not be available again.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/410].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-410-gone].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#410].
+  #
+  class HTTPGone < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Length Required</tt> responses (status code 411).
+  #
+  # The request did not specify the length of its content,
+  # which is required by the requested resource.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/411].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-411-length-required].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#411].
+  #
+  class HTTPLengthRequired < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Precondition Failed</tt> responses (status code 412).
+  #
+  # The server does not meet one of the preconditions
+  # specified in the request headers.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/412].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-412-precondition-failed].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#412].
+  #
+  class HTTPPreconditionFailed < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Payload Too Large</tt> responses (status code 413).
+  #
+  # The request is larger than the server is willing or able to process.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/413].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-413-content-too-large].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#413].
+  #
+  class HTTPPayloadTooLarge < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+  HTTPRequestEntityTooLarge = HTTPPayloadTooLarge
+
+  # Response class for <tt>URI Too Long</tt> responses (status code 414).
+  #
+  # The URI provided was too long for the server to process.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/414].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-414-uri-too-long].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#414].
+  #
+  class HTTPURITooLong < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+  HTTPRequestURITooLong = HTTPURITooLong
+  HTTPRequestURITooLarge = HTTPRequestURITooLong
+
+  # Response class for <tt>Unsupported Media Type</tt> responses (status code 415).
+  #
+  # The request entity has a media type which the server or resource does not support.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/415].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-415-unsupported-media-type].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#415].
+  #
+  class HTTPUnsupportedMediaType < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Range Not Satisfiable</tt> responses (status code 416).
+  #
+  # The request entity has a media type which the server or resource does not support.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/416].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-416-range-not-satisfiable].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#416].
+  #
+  class HTTPRangeNotSatisfiable < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+  HTTPRequestedRangeNotSatisfiable = HTTPRangeNotSatisfiable
+
+  # Response class for <tt>Expectation Failed</tt> responses (status code 417).
+  #
+  # The server cannot meet the requirements of the Expect request-header field.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/417].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-417-expectation-failed].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#417].
+  #
+  class HTTPExpectationFailed < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # 418 I'm a teapot - RFC 2324; a joke RFC
+  # See https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#418.
+
+  # 420 Enhance Your Calm - Twitter
+
+  # Response class for <tt>Misdirected Request</tt> responses (status code 421).
+  #
+  # The request was directed at a server that is not able to produce a response.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-421-misdirected-request].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#421].
+  #
+  class HTTPMisdirectedRequest < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Unprocessable Entity</tt> responses (status code 422).
+  #
+  # The request was well-formed but had semantic errors.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/422].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-422-unprocessable-content].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#422].
+  #
+  class HTTPUnprocessableEntity < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Locked (WebDAV)</tt> responses (status code 423).
+  #
+  # The requested resource is locked.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {RFC 4918}[https://www.rfc-editor.org/rfc/rfc4918#section-11.3].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#423].
+  #
+  class HTTPLocked < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Failed Dependency (WebDAV)</tt> responses (status code 424).
+  #
+  # The request failed because it depended on another request and that request failed.
+  # See {424 Failed Dependency (WebDAV)}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#424].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {RFC 4918}[https://www.rfc-editor.org/rfc/rfc4918#section-11.4].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#424].
+  #
+  class HTTPFailedDependency < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # 425 Too Early
+  # https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#425.
+
+  # Response class for <tt>Upgrade Required</tt> responses (status code 426).
+  #
+  # The client should switch to the protocol given in the Upgrade header field.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/426].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-426-upgrade-required].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#426].
+  #
+  class HTTPUpgradeRequired < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Precondition Required</tt> responses (status code 428).
+  #
+  # The origin server requires the request to be conditional.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/428].
+  # - {RFC 6585}[https://www.rfc-editor.org/rfc/rfc6585#section-3].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#428].
+  #
+  class HTTPPreconditionRequired < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Too Many Requests</tt> responses (status code 429).
+  #
+  # The user has sent too many requests in a given amount of time.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/429].
+  # - {RFC 6585}[https://www.rfc-editor.org/rfc/rfc6585#section-4].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#429].
+  #
+  class HTTPTooManyRequests < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Request Header Fields Too Large</tt> responses (status code 431).
+  #
+  # An individual header field is too large,
+  # or all the header fields collectively, are too large.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/431].
+  # - {RFC 6585}[https://www.rfc-editor.org/rfc/rfc6585#section-5].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#431].
+  #
+  class HTTPRequestHeaderFieldsTooLarge < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Unavailable For Legal Reasons</tt> responses (status code 451).
+  #
+  # A server operator has received a legal demand to deny access to a resource or to a set of resources
+  # that includes the requested resource.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/451].
+  # - {RFC 7725}[https://www.rfc-editor.org/rfc/rfc7725.html#section-3].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#451].
+  #
+  class HTTPUnavailableForLegalReasons < HTTPClientError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+  # 444 No Response - Nginx
+  # 449 Retry With - Microsoft
+  # 450 Blocked by Windows Parental Controls - Microsoft
+  # 499 Client Closed Request - Nginx
+
+  # Response class for <tt>Internal Server Error</tt> responses (status code 500).
+  #
+  # An unexpected condition was encountered and no more specific message is suitable.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/500].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-500-internal-server-error].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#500].
+  #
+  class HTTPInternalServerError < HTTPServerError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Not Implemented</tt> responses (status code 501).
+  #
+  # The server either does not recognize the request method,
+  # or it lacks the ability to fulfil the request.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/501].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-501-not-implemented].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#501].
+  #
+  class HTTPNotImplemented < HTTPServerError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Bad Gateway</tt> responses (status code 502).
+  #
+  # The server was acting as a gateway or proxy
+  # and received an invalid response from the upstream server.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/502].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-502-bad-gateway].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#502].
+  #
+  class HTTPBadGateway < HTTPServerError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Service Unavailable</tt> responses (status code 503).
+  #
+  # The server cannot handle the request
+  # (because it is overloaded or down for maintenance).
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/503].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-503-service-unavailable].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#503].
+  #
+  class HTTPServiceUnavailable < HTTPServerError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Gateway Timeout</tt> responses (status code 504).
+  #
+  # The server was acting as a gateway or proxy
+  # and did not receive a timely response from the upstream server.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/504].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-504-gateway-timeout].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#504].
+  #
+  class HTTPGatewayTimeout < HTTPServerError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+  HTTPGatewayTimeOut = HTTPGatewayTimeout
+
+  # Response class for <tt>HTTP Version Not Supported</tt> responses (status code 505).
+  #
+  # The server does not support the HTTP version used in the request.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/505].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-505-http-version-not-suppor].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#505].
+  #
+  class HTTPVersionNotSupported < HTTPServerError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Variant Also Negotiates</tt> responses (status code 506).
+  #
+  # Transparent content negotiation for the request results in a circular reference.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/506].
+  # - {RFC 2295}[https://www.rfc-editor.org/rfc/rfc2295#section-8.1].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#506].
+  #
+  class HTTPVariantAlsoNegotiates < HTTPServerError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Insufficient Storage (WebDAV)</tt> responses (status code 507).
+  #
+  # The server is unable to store the representation needed to complete the request.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/507].
+  # - {RFC 4918}[https://www.rfc-editor.org/rfc/rfc4918#section-11.5].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#507].
+  #
+  class HTTPInsufficientStorage < HTTPServerError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Loop Detected (WebDAV)</tt> responses (status code 508).
+  #
+  # The server detected an infinite loop while processing the request.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/508].
+  # - {RFC 5942}[https://www.rfc-editor.org/rfc/rfc5842.html#section-7.2].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#508].
+  #
+  class HTTPLoopDetected < HTTPServerError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+  # 509 Bandwidth Limit Exceeded - Apache bw/limited extension
+
+  # Response class for <tt>Not Extended</tt> responses (status code 510).
+  #
+  # Further extensions to the request are required for the server to fulfill it.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/510].
+  # - {RFC 2774}[https://www.rfc-editor.org/rfc/rfc2774.html#section-7].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#510].
+  #
+  class HTTPNotExtended < HTTPServerError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+  # Response class for <tt>Network Authentication Required</tt> responses (status code 511).
+  #
+  # The client needs to authenticate to gain network access.
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/511].
+  # - {RFC 6585}[https://www.rfc-editor.org/rfc/rfc6585#section-6].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#511].
+  #
+  class HTTPNetworkAuthenticationRequired < HTTPServerError
+    # :stopdoc:
+    HAS_BODY = true
+  end
+
+end
+
+class Net::HTTPResponse
+  # :stopdoc:
+  CODE_CLASS_TO_OBJ = {
+    '1' => Net::HTTPInformation,
+    '2' => Net::HTTPSuccess,
+    '3' => Net::HTTPRedirection,
+    '4' => Net::HTTPClientError,
+    '5' => Net::HTTPServerError
+  }.freeze
+  CODE_TO_OBJ = {
+    '100' => Net::HTTPContinue,
+    '101' => Net::HTTPSwitchProtocol,
+    '102' => Net::HTTPProcessing,
+    '103' => Net::HTTPEarlyHints,
+
+    '200' => Net::HTTPOK,
+    '201' => Net::HTTPCreated,
+    '202' => Net::HTTPAccepted,
+    '203' => Net::HTTPNonAuthoritativeInformation,
+    '204' => Net::HTTPNoContent,
+    '205' => Net::HTTPResetContent,
+    '206' => Net::HTTPPartialContent,
+    '207' => Net::HTTPMultiStatus,
+    '208' => Net::HTTPAlreadyReported,
+    '226' => Net::HTTPIMUsed,
+
+    '300' => Net::HTTPMultipleChoices,
+    '301' => Net::HTTPMovedPermanently,
+    '302' => Net::HTTPFound,
+    '303' => Net::HTTPSeeOther,
+    '304' => Net::HTTPNotModified,
+    '305' => Net::HTTPUseProxy,
+    '307' => Net::HTTPTemporaryRedirect,
+    '308' => Net::HTTPPermanentRedirect,
+
+    '400' => Net::HTTPBadRequest,
+    '401' => Net::HTTPUnauthorized,
+    '402' => Net::HTTPPaymentRequired,
+    '403' => Net::HTTPForbidden,
+    '404' => Net::HTTPNotFound,
+    '405' => Net::HTTPMethodNotAllowed,
+    '406' => Net::HTTPNotAcceptable,
+    '407' => Net::HTTPProxyAuthenticationRequired,
+    '408' => Net::HTTPRequestTimeout,
+    '409' => Net::HTTPConflict,
+    '410' => Net::HTTPGone,
+    '411' => Net::HTTPLengthRequired,
+    '412' => Net::HTTPPreconditionFailed,
+    '413' => Net::HTTPPayloadTooLarge,
+    '414' => Net::HTTPURITooLong,
+    '415' => Net::HTTPUnsupportedMediaType,
+    '416' => Net::HTTPRangeNotSatisfiable,
+    '417' => Net::HTTPExpectationFailed,
+    '421' => Net::HTTPMisdirectedRequest,
+    '422' => Net::HTTPUnprocessableEntity,
+    '423' => Net::HTTPLocked,
+    '424' => Net::HTTPFailedDependency,
+    '426' => Net::HTTPUpgradeRequired,
+    '428' => Net::HTTPPreconditionRequired,
+    '429' => Net::HTTPTooManyRequests,
+    '431' => Net::HTTPRequestHeaderFieldsTooLarge,
+    '451' => Net::HTTPUnavailableForLegalReasons,
+
+    '500' => Net::HTTPInternalServerError,
+    '501' => Net::HTTPNotImplemented,
+    '502' => Net::HTTPBadGateway,
+    '503' => Net::HTTPServiceUnavailable,
+    '504' => Net::HTTPGatewayTimeout,
+    '505' => Net::HTTPVersionNotSupported,
+    '506' => Net::HTTPVariantAlsoNegotiates,
+    '507' => Net::HTTPInsufficientStorage,
+    '508' => Net::HTTPLoopDetected,
+    '510' => Net::HTTPNotExtended,
+    '511' => Net::HTTPNetworkAuthenticationRequired,
+  }.freeze
+end
diff --git a/lib/net/http/status.rb b/lib/net/http/status.rb
new file mode 100644
index 0000000000..e70b47d9fb
--- /dev/null
+++ b/lib/net/http/status.rb
@@ -0,0 +1,84 @@
+# frozen_string_literal: true
+
+require_relative '../http'
+
+if $0 == __FILE__
+  require 'open-uri'
+  File.foreach(__FILE__) do |line|
+    puts line
+    break if line.start_with?('end')
+  end
+  puts
+  puts "Net::HTTP::STATUS_CODES = {"
+  url = "https://www.iana.org/assignments/http-status-codes/http-status-codes-1.csv"
+  URI(url).read.each_line do |line|
+    code, mes, = line.split(',')
+    next if ['(Unused)', 'Unassigned', 'Description'].include?(mes)
+    puts "  #{code} => '#{mes}',"
+  end
+  puts "} # :nodoc:"
+end
+
+Net::HTTP::STATUS_CODES = {
+  100 => 'Continue',
+  101 => 'Switching Protocols',
+  102 => 'Processing',
+  103 => 'Early Hints',
+  200 => 'OK',
+  201 => 'Created',
+  202 => 'Accepted',
+  203 => 'Non-Authoritative Information',
+  204 => 'No Content',
+  205 => 'Reset Content',
+  206 => 'Partial Content',
+  207 => 'Multi-Status',
+  208 => 'Already Reported',
+  226 => 'IM Used',
+  300 => 'Multiple Choices',
+  301 => 'Moved Permanently',
+  302 => 'Found',
+  303 => 'See Other',
+  304 => 'Not Modified',
+  305 => 'Use Proxy',
+  307 => 'Temporary Redirect',
+  308 => 'Permanent Redirect',
+  400 => 'Bad Request',
+  401 => 'Unauthorized',
+  402 => 'Payment Required',
+  403 => 'Forbidden',
+  404 => 'Not Found',
+  405 => 'Method Not Allowed',
+  406 => 'Not Acceptable',
+  407 => 'Proxy Authentication Required',
+  408 => 'Request Timeout',
+  409 => 'Conflict',
+  410 => 'Gone',
+  411 => 'Length Required',
+  412 => 'Precondition Failed',
+  413 => 'Content Too Large',
+  414 => 'URI Too Long',
+  415 => 'Unsupported Media Type',
+  416 => 'Range Not Satisfiable',
+  417 => 'Expectation Failed',
+  421 => 'Misdirected Request',
+  422 => 'Unprocessable Content',
+  423 => 'Locked',
+  424 => 'Failed Dependency',
+  425 => 'Too Early',
+  426 => 'Upgrade Required',
+  428 => 'Precondition Required',
+  429 => 'Too Many Requests',
+  431 => 'Request Header Fields Too Large',
+  451 => 'Unavailable For Legal Reasons',
+  500 => 'Internal Server Error',
+  501 => 'Not Implemented',
+  502 => 'Bad Gateway',
+  503 => 'Service Unavailable',
+  504 => 'Gateway Timeout',
+  505 => 'HTTP Version Not Supported',
+  506 => 'Variant Also Negotiates',
+  507 => 'Insufficient Storage',
+  508 => 'Loop Detected',
+  510 => 'Not Extended (OBSOLETED)',
+  511 => 'Network Authentication Required',
+} # :nodoc:
diff --git a/lib/net/https.rb b/lib/net/https.rb
index d36f82002d..0f23e1fb13 100644
--- a/lib/net/https.rb
+++ b/lib/net/https.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 =begin
 
 = net/https -- SSL/TLS enhancement for Net::HTTP.
@@ -13,10 +14,10 @@
   All rights reserved.
 
 == Licence
-  This program is licenced under the same licence as Ruby.
+  This program is licensed under the same licence as Ruby.
   (See the file 'LICENCE'.)
 
 =end
 
-require 'net/http'
+require_relative 'http'
 require 'openssl'
diff --git a/lib/net/imap.rb b/lib/net/imap.rb
deleted file mode 100644
index df9ee8ce1e..0000000000
--- a/lib/net/imap.rb
+++ /dev/null
@@ -1,3677 +0,0 @@
-#
-# = net/imap.rb
-#
-# Copyright (C) 2000  Shugo Maeda <shugo@ruby-lang.org>
-#
-# This library is distributed under the terms of the Ruby license.
-# You can freely distribute/modify this library.
-#
-# Documentation: Shugo Maeda, with RDoc conversion and overview by William
-# Webber.
-#
-# See Net::IMAP for documentation.
-#
-
-
-require "socket"
-require "monitor"
-require "digest/md5"
-require "strscan"
-begin
-  require "openssl"
-rescue LoadError
-end
-
-module Net
-
-  #
-  # Net::IMAP implements Internet Message Access Protocol (IMAP) client
-  # functionality.  The protocol is described in [IMAP].
-  #
-  # == IMAP Overview
-  #
-  # An IMAP client connects to a server, and then authenticates
-  # itself using either #authenticate() or #login().  Having
-  # authenticated itself, there is a range of commands
-  # available to it.  Most work with mailboxes, which may be
-  # arranged in an hierarchical namespace, and each of which
-  # contains zero or more messages.  How this is implemented on
-  # the server is implementation-dependent; on a UNIX server, it
-  # will frequently be implemented as a files in mailbox format
-  # within a hierarchy of directories.
-  #
-  # To work on the messages within a mailbox, the client must
-  # first select that mailbox, using either #select() or (for
-  # read-only access) #examine().  Once the client has successfully
-  # selected a mailbox, they enter _selected_ state, and that
-  # mailbox becomes the _current_ mailbox, on which mail-item
-  # related commands implicitly operate.
-  #
-  # Messages have two sorts of identifiers: message sequence
-  # numbers, and UIDs.
-  #
-  # Message sequence numbers number messages within a mail box
-  # from 1 up to the number of items in the mail box.  If new
-  # message arrives during a session, it receives a sequence
-  # number equal to the new size of the mail box.  If messages
-  # are expunged from the mailbox, remaining messages have their
-  # sequence numbers "shuffled down" to fill the gaps.
-  #
-  # UIDs, on the other hand, are permanently guaranteed not to
-  # identify another message within the same mailbox, even if
-  # the existing message is deleted.  UIDs are required to
-  # be assigned in ascending (but not necessarily sequential)
-  # order within a mailbox; this means that if a non-IMAP client
-  # rearranges the order of mailitems within a mailbox, the
-  # UIDs have to be reassigned.  An IMAP client cannot thus
-  # rearrange message orders.
-  #
-  # == Examples of Usage
-  #
-  # === List sender and subject of all recent messages in the default mailbox
-  #
-  #   imap = Net::IMAP.new('mail.example.com')
-  #   imap.authenticate('LOGIN', 'joe_user', 'joes_password')
-  #   imap.examine('INBOX')
-  #   imap.search(["RECENT"]).each do |message_id|
-  #     envelope = imap.fetch(message_id, "ENVELOPE")[0].attr["ENVELOPE"]
-  #     puts "#{envelope.from[0].name}: \t#{envelope.subject}"
-  #   end
-  #
-  # === Move all messages from April 2003 from "Mail/sent-mail" to "Mail/sent-apr03"
-  #
-  #   imap = Net::IMAP.new('mail.example.com')
-  #   imap.authenticate('LOGIN', 'joe_user', 'joes_password')
-  #   imap.select('Mail/sent-mail')
-  #   if not imap.list('Mail/', 'sent-apr03')
-  #     imap.create('Mail/sent-apr03')
-  #   end
-  #   imap.search(["BEFORE", "30-Apr-2003", "SINCE", "1-Apr-2003"]).each do |message_id|
-  #     imap.copy(message_id, "Mail/sent-apr03")
-  #     imap.store(message_id, "+FLAGS", [:Deleted])
-  #   end
-  #   imap.expunge
-  #
-  # == Thread Safety
-  #
-  # Net::IMAP supports concurrent threads. For example,
-  #
-  #   imap = Net::IMAP.new("imap.foo.net", "imap2")
-  #   imap.authenticate("cram-md5", "bar", "password")
-  #   imap.select("inbox")
-  #   fetch_thread = Thread.start { imap.fetch(1..-1, "UID") }
-  #   search_result = imap.search(["BODY", "hello"])
-  #   fetch_result = fetch_thread.value
-  #   imap.disconnect
-  #
-  # This script invokes the FETCH command and the SEARCH command concurrently.
-  #
-  # == Errors
-  #
-  # An IMAP server can send three different types of responses to indicate
-  # failure:
-  #
-  # NO:: the attempted command could not be successfully completed.  For
-  #      instance, the username/password used for logging in are incorrect;
-  #      the selected mailbox does not exists; etc.
-  #
-  # BAD:: the request from the client does not follow the server's
-  #       understanding of the IMAP protocol.  This includes attempting
-  #       commands from the wrong client state; for instance, attempting
-  #       to perform a SEARCH command without having SELECTed a current
-  #       mailbox.  It can also signal an internal server
-  #       failure (such as a disk crash) has occurred.
-  #
-  # BYE:: the server is saying goodbye.  This can be part of a normal
-  #       logout sequence, and can be used as part of a login sequence
-  #       to indicate that the server is (for some reason) unwilling
-  #       to accept our connection.  As a response to any other command,
-  #       it indicates either that the server is shutting down, or that
-  #       the server is timing out the client connection due to inactivity.
-  #
-  # These three error response are represented by the errors
-  # Net::IMAP::NoResponseError, Net::IMAP::BadResponseError, and
-  # Net::IMAP::ByeResponseError, all of which are subclasses of
-  # Net::IMAP::ResponseError.  Essentially, all methods that involve
-  # sending a request to the server can generate one of these errors.
-  # Only the most pertinent instances have been documented below.
-  #
-  # Because the IMAP class uses Sockets for communication, its methods
-  # are also susceptible to the various errors that can occur when
-  # working with sockets.  These are generally represented as
-  # Errno errors.  For instance, any method that involves sending a
-  # request to the server and/or receiving a response from it could
-  # raise an Errno::EPIPE error if the network connection unexpectedly
-  # goes down.  See the socket(7), ip(7), tcp(7), socket(2), connect(2),
-  # and associated man pages.
-  #
-  # Finally, a Net::IMAP::DataFormatError is thrown if low-level data
-  # is found to be in an incorrect format (for instance, when converting
-  # between UTF-8 and UTF-16), and Net::IMAP::ResponseParseError is
-  # thrown if a server response is non-parseable.
-  #
-  #
-  # == References
-  #
-  # [[IMAP]]
-  #    M. Crispin, "INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1",
-  #    RFC 2060, December 1996.  (Note: since obsoleted by RFC 3501)
-  #
-  # [[LANGUAGE-TAGS]]
-  #    Alvestrand, H., "Tags for the Identification of
-  #    Languages", RFC 1766, March 1995.
-  #
-  # [[MD5]]
-  #    Myers, J., and M. Rose, "The Content-MD5 Header Field", RFC
-  #    1864, October 1995.
-  #
-  # [[MIME-IMB]]
-  #    Freed, N., and N. Borenstein, "MIME (Multipurpose Internet
-  #    Mail Extensions) Part One: Format of Internet Message Bodies", RFC
-  #    2045, November 1996.
-  #
-  # [[RFC-822]]
-  #    Crocker, D., "Standard for the Format of ARPA Internet Text
-  #    Messages", STD 11, RFC 822, University of Delaware, August 1982.
-  #
-  # [[RFC-2087]]
-  #    Myers, J., "IMAP4 QUOTA extension", RFC 2087, January 1997.
-  #
-  # [[RFC-2086]]
-  #    Myers, J., "IMAP4 ACL extension", RFC 2086, January 1997.
-  #
-  # [[RFC-2195]]
-  #    Klensin, J., Catoe, R., and Krumviede, P., "IMAP/POP AUTHorize Extension
-  #    for Simple Challenge/Response", RFC 2195, September 1997.
-  #
-  # [[SORT-THREAD-EXT]]
-  #    Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - SORT and THREAD
-  #    Extensions", draft-ietf-imapext-sort, May 2003.
-  #
-  # [[OSSL]]
-  #    http://www.openssl.org
-  #
-  # [[RSSL]]
-  #    http://savannah.gnu.org/projects/rubypki
-  #
-  # [[UTF7]]
-  #    Goldsmith, D. and Davis, M., "UTF-7: A Mail-Safe Transformation Format of
-  #    Unicode", RFC 2152, May 1997.
-  #
-  class IMAP
-    include MonitorMixin
-    if defined?(OpenSSL)
-      include OpenSSL
-      include SSL
-    end
-
-    #  Returns an initial greeting response from the server.
-    attr_reader :greeting
-
-    # Returns recorded untagged responses.  For example:
-    #
-    #   imap.select("inbox")
-    #   p imap.responses["EXISTS"][-1]
-    #   #=> 2
-    #   p imap.responses["UIDVALIDITY"][-1]
-    #   #=> 968263756
-    attr_reader :responses
-
-    # Returns all response handlers.
-    attr_reader :response_handlers
-
-    # The thread to receive exceptions.
-    attr_accessor :client_thread
-
-    # Flag indicating a message has been seen
-    SEEN = :Seen
-
-    # Flag indicating a message has been answered
-    ANSWERED = :Answered
-
-    # Flag indicating a message has been flagged for special or urgent
-    # attention
-    FLAGGED = :Flagged
-
-    # Flag indicating a message has been marked for deletion.  This
-    # will occur when the mailbox is closed or expunged.
-    DELETED = :Deleted
-
-    # Flag indicating a message is only a draft or work-in-progress version.
-    DRAFT = :Draft
-
-    # Flag indicating that the message is "recent", meaning that this
-    # session is the first session in which the client has been notified
-    # of this message.
-    RECENT = :Recent
-
-    # Flag indicating that a mailbox context name cannot contain
-    # children.
-    NOINFERIORS = :Noinferiors
-
-    # Flag indicating that a mailbox is not selected.
-    NOSELECT = :Noselect
-
-    # Flag indicating that a mailbox has been marked "interesting" by
-    # the server; this commonly indicates that the mailbox contains
-    # new messages.
-    MARKED = :Marked
-
-    # Flag indicating that the mailbox does not contains new messages.
-    UNMARKED = :Unmarked
-
-    # Returns the debug mode.
-    def self.debug
-      return @@debug
-    end
-
-    # Sets the debug mode.
-    def self.debug=(val)
-      return @@debug = val
-    end
-
-    # Returns the max number of flags interned to symbols.
-    def self.max_flag_count
-      return @@max_flag_count
-    end
-
-    # Sets the max number of flags interned to symbols.
-    def self.max_flag_count=(count)
-      @@max_flag_count = count
-    end
-
-    # Adds an authenticator for Net::IMAP#authenticate.  +auth_type+
-    # is the type of authentication this authenticator supports
-    # (for instance, "LOGIN").  The +authenticator+ is an object
-    # which defines a process() method to handle authentication with
-    # the server.  See Net::IMAP::LoginAuthenticator,
-    # Net::IMAP::CramMD5Authenticator, and Net::IMAP::DigestMD5Authenticator
-    # for examples.
-    #
-    #
-    # If +auth_type+ refers to an existing authenticator, it will be
-    # replaced by the new one.
-    def self.add_authenticator(auth_type, authenticator)
-      @@authenticators[auth_type] = authenticator
-    end
-
-    # Disconnects from the server.
-    def disconnect
-      begin
-        begin
-          # try to call SSL::SSLSocket#io.
-          @sock.io.shutdown
-        rescue NoMethodError
-          # @sock is not an SSL::SSLSocket.
-          @sock.shutdown
-        end
-      rescue Errno::ENOTCONN
-        # ignore `Errno::ENOTCONN: Socket is not connected' on some platforms.
-      rescue Exception => e
-        @receiver_thread.raise(e)
-      end
-      @receiver_thread.join
-      synchronize do
-        unless @sock.closed?
-          @sock.close
-        end
-      end
-      raise e if e
-    end
-
-    # Returns true if disconnected from the server.
-    def disconnected?
-      return @sock.closed?
-    end
-
-    # Sends a CAPABILITY command, and returns an array of
-    # capabilities that the server supports.  Each capability
-    # is a string.  See [IMAP] for a list of possible
-    # capabilities.
-    #
-    # Note that the Net::IMAP class does not modify its
-    # behaviour according to the capabilities of the server;
-    # it is up to the user of the class to ensure that
-    # a certain capability is supported by a server before
-    # using it.
-    def capability
-      synchronize do
-        send_command("CAPABILITY")
-        return @responses.delete("CAPABILITY")[-1]
-      end
-    end
-
-    # Sends a NOOP command to the server. It does nothing.
-    def noop
-      send_command("NOOP")
-    end
-
-    # Sends a LOGOUT command to inform the server that the client is
-    # done with the connection.
-    def logout
-      send_command("LOGOUT")
-    end
-
-    # Sends a STARTTLS command to start TLS session.
-    def starttls(options = {}, verify = true)
-      send_command("STARTTLS") do |resp|
-        if resp.kind_of?(TaggedResponse) && resp.name == "OK"
-          begin
-            # for backward compatibility
-            certs = options.to_str
-            options = create_ssl_params(certs, verify)
-          rescue NoMethodError
-          end
-          start_tls_session(options)
-        end
-      end
-    end
-
-    # Sends an AUTHENTICATE command to authenticate the client.
-    # The +auth_type+ parameter is a string that represents
-    # the authentication mechanism to be used. Currently Net::IMAP
-    # supports authentication mechanisms:
-    #
-    #   LOGIN:: login using cleartext user and password.
-    #   CRAM-MD5:: login with cleartext user and encrypted password
-    #              (see [RFC-2195] for a full description).  This
-    #              mechanism requires that the server have the user's
-    #              password stored in clear-text password.
-    #
-    # For both these mechanisms, there should be two +args+: username
-    # and (cleartext) password.  A server may not support one or other
-    # of these mechanisms; check #capability() for a capability of
-    # the form "AUTH=LOGIN" or "AUTH=CRAM-MD5".
-    #
-    # Authentication is done using the appropriate authenticator object:
-    # see @@authenticators for more information on plugging in your own
-    # authenticator.
-    #
-    # For example:
-    #
-    #    imap.authenticate('LOGIN', user, password)
-    #
-    # A Net::IMAP::NoResponseError is raised if authentication fails.
-    def authenticate(auth_type, *args)
-      auth_type = auth_type.upcase
-      unless @@authenticators.has_key?(auth_type)
-        raise ArgumentError,
-          format('unknown auth type - "%s"', auth_type)
-      end
-      authenticator = @@authenticators[auth_type].new(*args)
-      send_command("AUTHENTICATE", auth_type) do |resp|
-        if resp.instance_of?(ContinuationRequest)
-          data = authenticator.process(resp.data.text.unpack("m")[0])
-          s = [data].pack("m").gsub(/\n/, "")
-          send_string_data(s)
-          put_string(CRLF)
-        end
-      end
-    end
-
-    # Sends a LOGIN command to identify the client and carries
-    # the plaintext +password+ authenticating this +user+.  Note
-    # that, unlike calling #authenticate() with an +auth_type+
-    # of "LOGIN", #login() does *not* use the login authenticator.
-    #
-    # A Net::IMAP::NoResponseError is raised if authentication fails.
-    def login(user, password)
-      send_command("LOGIN", user, password)
-    end
-
-    # Sends a SELECT command to select a +mailbox+ so that messages
-    # in the +mailbox+ can be accessed.
-    #
-    # After you have selected a mailbox, you may retrieve the
-    # number of items in that mailbox from @responses["EXISTS"][-1],
-    # and the number of recent messages from @responses["RECENT"][-1].
-    # Note that these values can change if new messages arrive
-    # during a session; see #add_response_handler() for a way of
-    # detecting this event.
-    #
-    # A Net::IMAP::NoResponseError is raised if the mailbox does not
-    # exist or is for some reason non-selectable.
-    def select(mailbox)
-      synchronize do
-        @responses.clear
-        send_command("SELECT", mailbox)
-      end
-    end
-
-    # Sends a EXAMINE command to select a +mailbox+ so that messages
-    # in the +mailbox+ can be accessed.  Behaves the same as #select(),
-    # except that the selected +mailbox+ is identified as read-only.
-    #
-    # A Net::IMAP::NoResponseError is raised if the mailbox does not
-    # exist or is for some reason non-examinable.
-    def examine(mailbox)
-      synchronize do
-        @responses.clear
-        send_command("EXAMINE", mailbox)
-      end
-    end
-
-    # Sends a CREATE command to create a new +mailbox+.
-    #
-    # A Net::IMAP::NoResponseError is raised if a mailbox with that name
-    # cannot be created.
-    def create(mailbox)
-      send_command("CREATE", mailbox)
-    end
-
-    # Sends a DELETE command to remove the +mailbox+.
-    #
-    # A Net::IMAP::NoResponseError is raised if a mailbox with that name
-    # cannot be deleted, either because it does not exist or because the
-    # client does not have permission to delete it.
-    def delete(mailbox)
-      send_command("DELETE", mailbox)
-    end
-
-    # Sends a RENAME command to change the name of the +mailbox+ to
-    # +newname+.
-    #
-    # A Net::IMAP::NoResponseError is raised if a mailbox with the
-    # name +mailbox+ cannot be renamed to +newname+ for whatever
-    # reason; for instance, because +mailbox+ does not exist, or
-    # because there is already a mailbox with the name +newname+.
-    def rename(mailbox, newname)
-      send_command("RENAME", mailbox, newname)
-    end
-
-    # Sends a SUBSCRIBE command to add the specified +mailbox+ name to
-    # the server's set of "active" or "subscribed" mailboxes as returned
-    # by #lsub().
-    #
-    # A Net::IMAP::NoResponseError is raised if +mailbox+ cannot be
-    # subscribed to, for instance because it does not exist.
-    def subscribe(mailbox)
-      send_command("SUBSCRIBE", mailbox)
-    end
-
-    # Sends a UNSUBSCRIBE command to remove the specified +mailbox+ name
-    # from the server's set of "active" or "subscribed" mailboxes.
-    #
-    # A Net::IMAP::NoResponseError is raised if +mailbox+ cannot be
-    # unsubscribed from, for instance because the client is not currently
-    # subscribed to it.
-    def unsubscribe(mailbox)
-      send_command("UNSUBSCRIBE", mailbox)
-    end
-
-    # Sends a LIST command, and returns a subset of names from
-    # the complete set of all names available to the client.
-    # +refname+ provides a context (for instance, a base directory
-    # in a directory-based mailbox hierarchy).  +mailbox+ specifies
-    # a mailbox or (via wildcards) mailboxes under that context.
-    # Two wildcards may be used in +mailbox+: '*', which matches
-    # all characters *including* the hierarchy delimiter (for instance,
-    # '/' on a UNIX-hosted directory-based mailbox hierarchy); and '%',
-    # which matches all characters *except* the hierarchy delimiter.
-    #
-    # If +refname+ is empty, +mailbox+ is used directly to determine
-    # which mailboxes to match.  If +mailbox+ is empty, the root
-    # name of +refname+ and the hierarchy delimiter are returned.
-    #
-    # The return value is an array of +Net::IMAP::MailboxList+. For example:
-    #
-    #   imap.create("foo/bar")
-    #   imap.create("foo/baz")
-    #   p imap.list("", "foo/%")
-    #   #=> [#<Net::IMAP::MailboxList attr=[:Noselect], delim="/", name="foo/">, \\
-    #        #<Net::IMAP::MailboxList attr=[:Noinferiors, :Marked], delim="/", name="foo/bar">, \\
-    #        #<Net::IMAP::MailboxList attr=[:Noinferiors], delim="/", name="foo/baz">]
-    def list(refname, mailbox)
-      synchronize do
-        send_command("LIST", refname, mailbox)
-        return @responses.delete("LIST")
-      end
-    end
-
-    # Sends a XLIST command, and returns a subset of names from
-    # the complete set of all names available to the client.
-    # +refname+ provides a context (for instance, a base directory
-    # in a directory-based mailbox hierarchy).  +mailbox+ specifies
-    # a mailbox or (via wildcards) mailboxes under that context.
-    # Two wildcards may be used in +mailbox+: '*', which matches
-    # all characters *including* the hierarchy delimiter (for instance,
-    # '/' on a UNIX-hosted directory-based mailbox hierarchy); and '%',
-    # which matches all characters *except* the hierarchy delimiter.
-    #
-    # If +refname+ is empty, +mailbox+ is used directly to determine
-    # which mailboxes to match.  If +mailbox+ is empty, the root
-    # name of +refname+ and the hierarchy delimiter are returned.
-    #
-    # The XLIST command is like the LIST command except that the flags
-    # returned refer to the function of the folder/mailbox, e.g. :Sent
-    #
-    # The return value is an array of +Net::IMAP::MailboxList+. For example:
-    #
-    #   imap.create("foo/bar")
-    #   imap.create("foo/baz")
-    #   p imap.xlist("", "foo/%")
-    #   #=> [#<Net::IMAP::MailboxList attr=[:Noselect], delim="/", name="foo/">, \\
-    #        #<Net::IMAP::MailboxList attr=[:Noinferiors, :Marked], delim="/", name="foo/bar">, \\
-    #        #<Net::IMAP::MailboxList attr=[:Noinferiors], delim="/", name="foo/baz">]
-    def xlist(refname, mailbox)
-      synchronize do
-        send_command("XLIST", refname, mailbox)
-        return @responses.delete("XLIST")
-      end
-    end
-
-    # Sends the GETQUOTAROOT command along with specified +mailbox+.
-    # This command is generally available to both admin and user.
-    # If mailbox exists, returns an array containing objects of
-    # Net::IMAP::MailboxQuotaRoot and Net::IMAP::MailboxQuota.
-    def getquotaroot(mailbox)
-      synchronize do
-        send_command("GETQUOTAROOT", mailbox)
-        result = []
-        result.concat(@responses.delete("QUOTAROOT"))
-        result.concat(@responses.delete("QUOTA"))
-        return result
-      end
-    end
-
-    # Sends the GETQUOTA command along with specified +mailbox+.
-    # If this mailbox exists, then an array containing a
-    # Net::IMAP::MailboxQuota object is returned.  This
-    # command generally is only available to server admin.
-    def getquota(mailbox)
-      synchronize do
-        send_command("GETQUOTA", mailbox)
-        return @responses.delete("QUOTA")
-      end
-    end
-
-    # Sends a SETQUOTA command along with the specified +mailbox+ and
-    # +quota+.  If +quota+ is nil, then quota will be unset for that
-    # mailbox.  Typically one needs to be logged in as server admin
-    # for this to work.  The IMAP quota commands are described in
-    # [RFC-2087].
-    def setquota(mailbox, quota)
-      if quota.nil?
-        data = '()'
-      else
-        data = '(STORAGE ' + quota.to_s + ')'
-      end
-      send_command("SETQUOTA", mailbox, RawData.new(data))
-    end
-
-    # Sends the SETACL command along with +mailbox+, +user+ and the
-    # +rights+ that user is to have on that mailbox.  If +rights+ is nil,
-    # then that user will be stripped of any rights to that mailbox.
-    # The IMAP ACL commands are described in [RFC-2086].
-    def setacl(mailbox, user, rights)
-      if rights.nil?
-        send_command("SETACL", mailbox, user, "")
-      else
-        send_command("SETACL", mailbox, user, rights)
-      end
-    end
-
-    # Send the GETACL command along with specified +mailbox+.
-    # If this mailbox exists, an array containing objects of
-    # Net::IMAP::MailboxACLItem will be returned.
-    def getacl(mailbox)
-      synchronize do
-        send_command("GETACL", mailbox)
-        return @responses.delete("ACL")[-1]
-      end
-    end
-
-    # Sends a LSUB command, and returns a subset of names from the set
-    # of names that the user has declared as being "active" or
-    # "subscribed".  +refname+ and +mailbox+ are interpreted as
-    # for #list().
-    # The return value is an array of +Net::IMAP::MailboxList+.
-    def lsub(refname, mailbox)
-      synchronize do
-        send_command("LSUB", refname, mailbox)
-        return @responses.delete("LSUB")
-      end
-    end
-
-    # Sends a STATUS command, and returns the status of the indicated
-    # +mailbox+. +attr+ is a list of one or more attributes that
-    # we are request the status of.  Supported attributes include:
-    #
-    #   MESSAGES:: the number of messages in the mailbox.
-    #   RECENT:: the number of recent messages in the mailbox.
-    #   UNSEEN:: the number of unseen messages in the mailbox.
-    #
-    # The return value is a hash of attributes. For example:
-    #
-    #   p imap.status("inbox", ["MESSAGES", "RECENT"])
-    #   #=> {"RECENT"=>0, "MESSAGES"=>44}
-    #
-    # A Net::IMAP::NoResponseError is raised if status values
-    # for +mailbox+ cannot be returned, for instance because it
-    # does not exist.
-    def status(mailbox, attr)
-      synchronize do
-        send_command("STATUS", mailbox, attr)
-        return @responses.delete("STATUS")[-1].attr
-      end
-    end
-
-    # Sends a APPEND command to append the +message+ to the end of
-    # the +mailbox+. The optional +flags+ argument is an array of
-    # flags to initially passing to the new message.  The optional
-    # +date_time+ argument specifies the creation time to assign to the
-    # new message; it defaults to the current time.
-    # For example:
-    #
-    #   imap.append("inbox", <<EOF.gsub(/\n/, "\r\n"), [:Seen], Time.now)
-    #   Subject: hello
-    #   From: shugo@ruby-lang.org
-    #   To: shugo@ruby-lang.org
-    #
-    #   hello world
-    #   EOF
-    #
-    # A Net::IMAP::NoResponseError is raised if the mailbox does
-    # not exist (it is not created automatically), or if the flags,
-    # date_time, or message arguments contain errors.
-    def append(mailbox, message, flags = nil, date_time = nil)
-      args = []
-      if flags
-        args.push(flags)
-      end
-      args.push(date_time) if date_time
-      args.push(Literal.new(message))
-      send_command("APPEND", mailbox, *args)
-    end
-
-    # Sends a CHECK command to request a checkpoint of the currently
-    # selected mailbox.  This performs implementation-specific
-    # housekeeping, for instance, reconciling the mailbox's
-    # in-memory and on-disk state.
-    def check
-      send_command("CHECK")
-    end
-
-    # Sends a CLOSE command to close the currently selected mailbox.
-    # The CLOSE command permanently removes from the mailbox all
-    # messages that have the \Deleted flag set.
-    def close
-      send_command("CLOSE")
-    end
-
-    # Sends a EXPUNGE command to permanently remove from the currently
-    # selected mailbox all messages that have the \Deleted flag set.
-    def expunge
-      synchronize do
-        send_command("EXPUNGE")
-        return @responses.delete("EXPUNGE")
-      end
-    end
-
-    # Sends a SEARCH command to search the mailbox for messages that
-    # match the given searching criteria, and returns message sequence
-    # numbers.  +keys+ can either be a string holding the entire
-    # search string, or a single-dimension array of search keywords and
-    # arguments.  The following are some common search criteria;
-    # see [IMAP] section 6.4.4 for a full list.
-    #
-    # <message set>:: a set of message sequence numbers.  ',' indicates
-    #                 an interval, ':' indicates a range.  For instance,
-    #                 '2,10:12,15' means "2,10,11,12,15".
-    #
-    # BEFORE <date>:: messages with an internal date strictly before
-    #                 <date>.  The date argument has a format similar
-    #                 to 8-Aug-2002.
-    #
-    # BODY <string>:: messages that contain <string> within their body.
-    #
-    # CC <string>:: messages containing <string> in their CC field.
-    #
-    # FROM <string>:: messages that contain <string> in their FROM field.
-    #
-    # NEW:: messages with the \Recent, but not the \Seen, flag set.
-    #
-    # NOT <search-key>:: negate the following search key.
-    #
-    # OR <search-key> <search-key>:: "or" two search keys together.
-    #
-    # ON <date>:: messages with an internal date exactly equal to <date>,
-    #             which has a format similar to 8-Aug-2002.
-    #
-    # SINCE <date>:: messages with an internal date on or after <date>.
-    #
-    # SUBJECT <string>:: messages with <string> in their subject.
-    #
-    # TO <string>:: messages with <string> in their TO field.
-    #
-    # For example:
-    #
-    #   p imap.search(["SUBJECT", "hello", "NOT", "NEW"])
-    #   #=> [1, 6, 7, 8]
-    def search(keys, charset = nil)
-      return search_internal("SEARCH", keys, charset)
-    end
-
-    # As for #search(), but returns unique identifiers.
-    def uid_search(keys, charset = nil)
-      return search_internal("UID SEARCH", keys, charset)
-    end
-
-    # Sends a FETCH command to retrieve data associated with a message
-    # in the mailbox. The +set+ parameter is a number or an array of
-    # numbers or a Range object. The number is a message sequence
-    # number.  +attr+ is a list of attributes to fetch; see the
-    # documentation for Net::IMAP::FetchData for a list of valid
-    # attributes.
-    # The return value is an array of Net::IMAP::FetchData. For example:
-    #
-    #   p imap.fetch(6..8, "UID")
-    #   #=> [#<Net::IMAP::FetchData seqno=6, attr={"UID"=>98}>, \\
-    #        #<Net::IMAP::FetchData seqno=7, attr={"UID"=>99}>, \\
-    #        #<Net::IMAP::FetchData seqno=8, attr={"UID"=>100}>]
-    #   p imap.fetch(6, "BODY[HEADER.FIELDS (SUBJECT)]")
-    #   #=> [#<Net::IMAP::FetchData seqno=6, attr={"BODY[HEADER.FIELDS (SUBJECT)]"=>"Subject: test\r\n\r\n"}>]
-    #   data = imap.uid_fetch(98, ["RFC822.SIZE", "INTERNALDATE"])[0]
-    #   p data.seqno
-    #   #=> 6
-    #   p data.attr["RFC822.SIZE"]
-    #   #=> 611
-    #   p data.attr["INTERNALDATE"]
-    #   #=> "12-Oct-2000 22:40:59 +0900"
-    #   p data.attr["UID"]
-    #   #=> 98
-    def fetch(set, attr)
-      return fetch_internal("FETCH", set, attr)
-    end
-
-    # As for #fetch(), but +set+ contains unique identifiers.
-    def uid_fetch(set, attr)
-      return fetch_internal("UID FETCH", set, attr)
-    end
-
-    # Sends a STORE command to alter data associated with messages
-    # in the mailbox, in particular their flags. The +set+ parameter
-    # is a number or an array of numbers or a Range object. Each number
-    # is a message sequence number.  +attr+ is the name of a data item
-    # to store: 'FLAGS' means to replace the message's flag list
-    # with the provided one; '+FLAGS' means to add the provided flags;
-    # and '-FLAGS' means to remove them.  +flags+ is a list of flags.
-    #
-    # The return value is an array of Net::IMAP::FetchData. For example:
-    #
-    #   p imap.store(6..8, "+FLAGS", [:Deleted])
-    #   #=> [#<Net::IMAP::FetchData seqno=6, attr={"FLAGS"=>[:Seen, :Deleted]}>, \\
-    #        #<Net::IMAP::FetchData seqno=7, attr={"FLAGS"=>[:Seen, :Deleted]}>, \\
-    #        #<Net::IMAP::FetchData seqno=8, attr={"FLAGS"=>[:Seen, :Deleted]}>]
-    def store(set, attr, flags)
-      return store_internal("STORE", set, attr, flags)
-    end
-
-    # As for #store(), but +set+ contains unique identifiers.
-    def uid_store(set, attr, flags)
-      return store_internal("UID STORE", set, attr, flags)
-    end
-
-    # Sends a COPY command to copy the specified message(s) to the end
-    # of the specified destination +mailbox+. The +set+ parameter is
-    # a number or an array of numbers or a Range object. The number is
-    # a message sequence number.
-    def copy(set, mailbox)
-      copy_internal("COPY", set, mailbox)
-    end
-
-    # As for #copy(), but +set+ contains unique identifiers.
-    def uid_copy(set, mailbox)
-      copy_internal("UID COPY", set, mailbox)
-    end
-
-    # Sends a SORT command to sort messages in the mailbox.
-    # Returns an array of message sequence numbers. For example:
-    #
-    #   p imap.sort(["FROM"], ["ALL"], "US-ASCII")
-    #   #=> [1, 2, 3, 5, 6, 7, 8, 4, 9]
-    #   p imap.sort(["DATE"], ["SUBJECT", "hello"], "US-ASCII")
-    #   #=> [6, 7, 8, 1]
-    #
-    # See [SORT-THREAD-EXT] for more details.
-    def sort(sort_keys, search_keys, charset)
-      return sort_internal("SORT", sort_keys, search_keys, charset)
-    end
-
-    # As for #sort(), but returns an array of unique identifiers.
-    def uid_sort(sort_keys, search_keys, charset)
-      return sort_internal("UID SORT", sort_keys, search_keys, charset)
-    end
-
-    # Adds a response handler. For example, to detect when
-    # the server sends us a new EXISTS response (which normally
-    # indicates new messages being added to the mail box),
-    # you could add the following handler after selecting the
-    # mailbox.
-    #
-    #   imap.add_response_handler { |resp|
-    #     if resp.kind_of?(Net::IMAP::UntaggedResponse) and resp.name == "EXISTS"
-    #       puts "Mailbox now has #{resp.data} messages"
-    #     end
-    #   }
-    #
-    def add_response_handler(handler = Proc.new)
-      @response_handlers.push(handler)
-    end
-
-    # Removes the response handler.
-    def remove_response_handler(handler)
-      @response_handlers.delete(handler)
-    end
-
-    # As for #search(), but returns message sequence numbers in threaded
-    # format, as a Net::IMAP::ThreadMember tree.  The supported algorithms
-    # are:
-    #
-    # ORDEREDSUBJECT:: split into single-level threads according to subject,
-    #                  ordered by date.
-    # REFERENCES:: split into threads by parent/child relationships determined
-    #              by which message is a reply to which.
-    #
-    # Unlike #search(), +charset+ is a required argument.  US-ASCII
-    # and UTF-8 are sample values.
-    #
-    # See [SORT-THREAD-EXT] for more details.
-    def thread(algorithm, search_keys, charset)
-      return thread_internal("THREAD", algorithm, search_keys, charset)
-    end
-
-    # As for #thread(), but returns unique identifiers instead of
-    # message sequence numbers.
-    def uid_thread(algorithm, search_keys, charset)
-      return thread_internal("UID THREAD", algorithm, search_keys, charset)
-    end
-
-    # Sends an IDLE command that waits for notifications of new or expunged
-    # messages.  Yields responses from the server during the IDLE.
-    #
-    # Use #idle_done() to leave IDLE.
-    def idle(&response_handler)
-      raise LocalJumpError, "no block given" unless response_handler
-
-      response = nil
-
-      synchronize do
-        tag = Thread.current[:net_imap_tag] = generate_tag
-        put_string("#{tag} IDLE#{CRLF}")
-
-        begin
-          add_response_handler(response_handler)
-          @idle_done_cond = new_cond
-          @idle_done_cond.wait
-          @idle_done_cond = nil
-          if @receiver_thread_terminating
-            raise Net::IMAP::Error, "connection closed"
-          end
-        ensure
-          unless @receiver_thread_terminating
-            remove_response_handler(response_handler)
-            put_string("DONE#{CRLF}")
-            response = get_tagged_response(tag, "IDLE")
-          end
-        end
-      end
-
-      return response
-    end
-
-    # Leaves IDLE.
-    def idle_done
-      synchronize do
-        if @idle_done_cond.nil?
-          raise Net::IMAP::Error, "not during IDLE"
-        end
-        @idle_done_cond.signal
-      end
-    end
-
-    # Decode a string from modified UTF-7 format to UTF-8.
-    #
-    # UTF-7 is a 7-bit encoding of Unicode [UTF7].  IMAP uses a
-    # slightly modified version of this to encode mailbox names
-    # containing non-ASCII characters; see [IMAP] section 5.1.3.
-    #
-    # Net::IMAP does _not_ automatically encode and decode
-    # mailbox names to and from utf7.
-    def self.decode_utf7(s)
-      return s.gsub(/&(.*?)-/n) {
-        if $1.empty?
-          "&"
-        else
-          base64 = $1.tr(",", "/")
-          x = base64.length % 4
-          if x > 0
-            base64.concat("=" * (4 - x))
-          end
-          base64.unpack("m")[0].unpack("n*").pack("U*")
-        end
-      }.force_encoding("UTF-8")
-    end
-
-    # Encode a string from UTF-8 format to modified UTF-7.
-    def self.encode_utf7(s)
-      return s.gsub(/(&)|([^\x20-\x7e]+)/u) {
-        if $1
-          "&-"
-        else
-          base64 = [$&.unpack("U*").pack("n*")].pack("m")
-          "&" + base64.delete("=\n").tr("/", ",") + "-"
-        end
-      }.force_encoding("ASCII-8BIT")
-    end
-
-    # Formats +time+ as an IMAP-style date.
-    def self.format_date(time)
-      return time.strftime('%d-%b-%Y')
-    end
-
-    # Formats +time+ as an IMAP-style date-time.
-    def self.format_datetime(time)
-      return time.strftime('%d-%b-%Y %H:%M %z')
-    end
-
-    private
-
-    CRLF = "\r\n"      # :nodoc:
-    PORT = 143         # :nodoc:
-    SSL_PORT = 993   # :nodoc:
-
-    @@debug = false
-    @@authenticators = {}
-    @@max_flag_count = 10000
-
-    # call-seq:
-    #    Net::IMAP.new(host, options = {})
-    #
-    # Creates a new Net::IMAP object and connects it to the specified
-    # +host+.
-    #
-    # +options+ is an option hash, each key of which is a symbol.
-    #
-    # The available options are:
-    #
-    # port::  port number (default value is 143 for imap, or 993 for imaps)
-    # ssl::   if options[:ssl] is true, then an attempt will be made
-    #         to use SSL (now TLS) to connect to the server.  For this to work
-    #         OpenSSL [OSSL] and the Ruby OpenSSL [RSSL] extensions need to
-    #         be installed.
-    #         if options[:ssl] is a hash, it's passed to
-    #         OpenSSL::SSL::SSLContext#set_params as parameters.
-    #
-    # The most common errors are:
-    #
-    # Errno::ECONNREFUSED:: connection refused by +host+ or an intervening
-    #                       firewall.
-    # Errno::ETIMEDOUT:: connection timed out (possibly due to packets
-    #                    being dropped by an intervening firewall).
-    # Errno::ENETUNREACH:: there is no route to that network.
-    # SocketError:: hostname not known or other socket error.
-    # Net::IMAP::ByeResponseError:: we connected to the host, but they
-    #                               immediately said goodbye to us.
-    def initialize(host, port_or_options = {},
-                   usessl = false, certs = nil, verify = true)
-      super()
-      @host = host
-      begin
-        options = port_or_options.to_hash
-      rescue NoMethodError
-        # for backward compatibility
-        options = {}
-        options[:port] = port_or_options
-        if usessl
-          options[:ssl] = create_ssl_params(certs, verify)
-        end
-      end
-      @port = options[:port] || (options[:ssl] ? SSL_PORT : PORT)
-      @tag_prefix = "RUBY"
-      @tagno = 0
-      @parser = ResponseParser.new
-      @sock = TCPSocket.open(@host, @port)
-      if options[:ssl]
-        start_tls_session(options[:ssl])
-        @usessl = true
-      else
-        @usessl = false
-      end
-      @responses = Hash.new([].freeze)
-      @tagged_responses = {}
-      @response_handlers = []
-      @tagged_response_arrival = new_cond
-      @continuation_request_arrival = new_cond
-      @idle_done_cond = nil
-      @logout_command_tag = nil
-      @debug_output_bol = true
-      @exception = nil
-
-      @greeting = get_response
-      if @greeting.name == "BYE"
-        @sock.close
-        raise ByeResponseError, @greeting
-      end
-
-      @client_thread = Thread.current
-      @receiver_thread = Thread.start {
-        begin
-          receive_responses
-        rescue Exception
-        end
-      }
-      @receiver_thread_terminating = false
-    end
-
-    def receive_responses
-      connection_closed = false
-      until connection_closed
-        synchronize do
-          @exception = nil
-        end
-        begin
-          resp = get_response
-        rescue Exception => e
-          synchronize do
-            @sock.close
-            @exception = e
-          end
-          break
-        end
-        unless resp
-          synchronize do
-            @exception = EOFError.new("end of file reached")
-          end
-          break
-        end
-        begin
-          synchronize do
-            case resp
-            when TaggedResponse
-              @tagged_responses[resp.tag] = resp
-              @tagged_response_arrival.broadcast
-              if resp.tag == @logout_command_tag
-                return
-              end
-            when UntaggedResponse
-              record_response(resp.name, resp.data)
-              if resp.data.instance_of?(ResponseText) &&
-                  (code = resp.data.code)
-                record_response(code.name, code.data)
-              end
-              if resp.name == "BYE" && @logout_command_tag.nil?
-                @sock.close
-                @exception = ByeResponseError.new(resp)
-                connection_closed = true
-              end
-            when ContinuationRequest
-              @continuation_request_arrival.signal
-            end
-            @response_handlers.each do |handler|
-              handler.call(resp)
-            end
-          end
-        rescue Exception => e
-          @exception = e
-          synchronize do
-            @tagged_response_arrival.broadcast
-            @continuation_request_arrival.broadcast
-          end
-        end
-      end
-      synchronize do
-        @receiver_thread_terminating = true
-        @tagged_response_arrival.broadcast
-        @continuation_request_arrival.broadcast
-        if @idle_done_cond
-          @idle_done_cond.signal 
-        end
-      end
-    end
-
-    def get_tagged_response(tag, cmd)
-      until @tagged_responses.key?(tag)
-        raise @exception if @exception
-        @tagged_response_arrival.wait
-      end
-      resp = @tagged_responses.delete(tag)
-      case resp.name
-      when /\A(?:NO)\z/ni
-        raise NoResponseError, resp
-      when /\A(?:BAD)\z/ni
-        raise BadResponseError, resp
-      else
-        return resp
-      end
-    end
-
-    def get_response
-      buff = ""
-      while true
-        s = @sock.gets(CRLF)
-        break unless s
-        buff.concat(s)
-        if /\{(\d+)\}\r\n/n =~ s
-          s = @sock.read($1.to_i)
-          buff.concat(s)
-        else
-          break
-        end
-      end
-      return nil if buff.length == 0
-      if @@debug
-        $stderr.print(buff.gsub(/^/n, "S: "))
-      end
-      return @parser.parse(buff)
-    end
-
-    def record_response(name, data)
-      unless @responses.has_key?(name)
-        @responses[name] = []
-      end
-      @responses[name].push(data)
-    end
-
-    def send_command(cmd, *args, &block)
-      synchronize do
-        args.each do |i|
-          validate_data(i)
-        end
-        tag = generate_tag
-        put_string(tag + " " + cmd)
-        args.each do |i|
-          put_string(" ")
-          send_data(i)
-        end
-        put_string(CRLF)
-        if cmd == "LOGOUT"
-          @logout_command_tag = tag
-        end
-        if block
-          add_response_handler(block)
-        end
-        begin
-          return get_tagged_response(tag, cmd)
-        ensure
-          if block
-            remove_response_handler(block)
-          end
-        end
-      end
-    end
-
-    def generate_tag
-      @tagno += 1
-      return format("%s%04d", @tag_prefix, @tagno)
-    end
-
-    def put_string(str)
-      @sock.print(str)
-      if @@debug
-        if @debug_output_bol
-          $stderr.print("C: ")
-        end
-        $stderr.print(str.gsub(/\n(?!\z)/n, "\nC: "))
-        if /\r\n\z/n.match(str)
-          @debug_output_bol = true
-        else
-          @debug_output_bol = false
-        end
-      end
-    end
-
-    def validate_data(data)
-      case data
-      when nil
-      when String
-      when Integer
-        if data < 0 || data >= 4294967296
-          raise DataFormatError, num.to_s
-        end
-      when Array
-        data.each do |i|
-          validate_data(i)
-        end
-      when Time
-      when Symbol
-      else
-        data.validate
-      end
-    end
-
-    def send_data(data)
-      case data
-      when nil
-        put_string("NIL")
-      when String
-        send_string_data(data)
-      when Integer
-        send_number_data(data)
-      when Array
-        send_list_data(data)
-      when Time
-        send_time_data(data)
-      when Symbol
-        send_symbol_data(data)
-      else
-        data.send_data(self)
-      end
-    end
-
-    def send_string_data(str)
-      case str
-      when ""
-        put_string('""')
-      when /[\x80-\xff\r\n]/n
-        # literal
-        send_literal(str)
-      when /[(){ \x00-\x1f\x7f%*"\\]/n
-        # quoted string
-        send_quoted_string(str)
-      else
-        put_string(str)
-      end
-    end
-
-    def send_quoted_string(str)
-      put_string('"' + str.gsub(/["\\]/n, "\\\\\\&") + '"')
-    end
-
-    def send_literal(str)
-      put_string("{" + str.bytesize.to_s + "}" + CRLF)
-      @continuation_request_arrival.wait
-      raise @exception if @exception
-      put_string(str)
-    end
-
-    def send_number_data(num)
-      put_string(num.to_s)
-    end
-
-    def send_list_data(list)
-      put_string("(")
-      first = true
-      list.each do |i|
-        if first
-          first = false
-        else
-          put_string(" ")
-        end
-        send_data(i)
-      end
-      put_string(")")
-    end
-
-    DATE_MONTH = %w(Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec)
-
-    def send_time_data(time)
-      t = time.dup.gmtime
-      s = format('"%2d-%3s-%4d %02d:%02d:%02d +0000"',
-                 t.day, DATE_MONTH[t.month - 1], t.year,
-                 t.hour, t.min, t.sec)
-      put_string(s)
-    end
-
-    def send_symbol_data(symbol)
-      put_string("\\" + symbol.to_s)
-    end
-
-    def search_internal(cmd, keys, charset)
-      if keys.instance_of?(String)
-        keys = [RawData.new(keys)]
-      else
-        normalize_searching_criteria(keys)
-      end
-      synchronize do
-        if charset
-          send_command(cmd, "CHARSET", charset, *keys)
-        else
-          send_command(cmd, *keys)
-        end
-        return @responses.delete("SEARCH")[-1]
-      end
-    end
-
-    def fetch_internal(cmd, set, attr)
-      case attr
-      when String then
-        attr = RawData.new(attr)
-      when Array then
-        attr = attr.map { |arg|
-          arg.is_a?(String) ? RawData.new(arg) : arg
-        }
-      end
-
-      synchronize do
-        @responses.delete("FETCH")
-        send_command(cmd, MessageSet.new(set), attr)
-        return @responses.delete("FETCH")
-      end
-    end
-
-    def store_internal(cmd, set, attr, flags)
-      if attr.instance_of?(String)
-        attr = RawData.new(attr)
-      end
-      synchronize do
-        @responses.delete("FETCH")
-        send_command(cmd, MessageSet.new(set), attr, flags)
-        return @responses.delete("FETCH")
-      end
-    end
-
-    def copy_internal(cmd, set, mailbox)
-      send_command(cmd, MessageSet.new(set), mailbox)
-    end
-
-    def sort_internal(cmd, sort_keys, search_keys, charset)
-      if search_keys.instance_of?(String)
-        search_keys = [RawData.new(search_keys)]
-      else
-        normalize_searching_criteria(search_keys)
-      end
-      normalize_searching_criteria(search_keys)
-      synchronize do
-        send_command(cmd, sort_keys, charset, *search_keys)
-        return @responses.delete("SORT")[-1]
-      end
-    end
-
-    def thread_internal(cmd, algorithm, search_keys, charset)
-      if search_keys.instance_of?(String)
-        search_keys = [RawData.new(search_keys)]
-      else
-        normalize_searching_criteria(search_keys)
-      end
-      normalize_searching_criteria(search_keys)
-      send_command(cmd, algorithm, charset, *search_keys)
-      return @responses.delete("THREAD")[-1]
-    end
-
-    def normalize_searching_criteria(keys)
-      keys.collect! do |i|
-        case i
-        when -1, Range, Array
-          MessageSet.new(i)
-        else
-          i
-        end
-      end
-    end
-
-    def create_ssl_params(certs = nil, verify = true)
-      params = {}
-      if certs
-        if File.file?(certs)
-          params[:ca_file] = certs
-        elsif File.directory?(certs)
-          params[:ca_path] = certs
-        end
-      end
-      if verify
-        params[:verify_mode] = VERIFY_PEER
-      else
-        params[:verify_mode] = VERIFY_NONE
-      end
-      return params
-    end
-
-    def start_tls_session(params = {})
-      unless defined?(OpenSSL)
-        raise "SSL extension not installed"
-      end
-      if @sock.kind_of?(OpenSSL::SSL::SSLSocket)
-        raise RuntimeError, "already using SSL"
-      end
-      begin
-        params = params.to_hash
-      rescue NoMethodError
-        params = {}
-      end
-      context = SSLContext.new
-      context.set_params(params)
-      if defined?(VerifyCallbackProc)
-        context.verify_callback = VerifyCallbackProc
-      end
-      @sock = SSLSocket.new(@sock, context)
-      @sock.sync_close = true
-      @sock.connect
-      if context.verify_mode != VERIFY_NONE
-        @sock.post_connection_check(@host)
-      end
-    end
-
-    class RawData # :nodoc:
-      def send_data(imap)
-        imap.send(:put_string, @data)
-      end
-
-      def validate
-      end
-
-      private
-
-      def initialize(data)
-        @data = data
-      end
-    end
-
-    class Atom # :nodoc:
-      def send_data(imap)
-        imap.send(:put_string, @data)
-      end
-
-      def validate
-      end
-
-      private
-
-      def initialize(data)
-        @data = data
-      end
-    end
-
-    class QuotedString # :nodoc:
-      def send_data(imap)
-        imap.send(:send_quoted_string, @data)
-      end
-
-      def validate
-      end
-
-      private
-
-      def initialize(data)
-        @data = data
-      end
-    end
-
-    class Literal # :nodoc:
-      def send_data(imap)
-        imap.send(:send_literal, @data)
-      end
-
-      def validate
-      end
-
-      private
-
-      def initialize(data)
-        @data = data
-      end
-    end
-
-    class MessageSet # :nodoc:
-      def send_data(imap)
-        imap.send(:put_string, format_internal(@data))
-      end
-
-      def validate
-        validate_internal(@data)
-      end
-
-      private
-
-      def initialize(data)
-        @data = data
-      end
-
-      def format_internal(data)
-        case data
-        when "*"
-          return data
-        when Integer
-          if data == -1
-            return "*"
-          else
-            return data.to_s
-          end
-        when Range
-          return format_internal(data.first) +
-            ":" + format_internal(data.last)
-        when Array
-          return data.collect {|i| format_internal(i)}.join(",")
-        when ThreadMember
-          return data.seqno.to_s +
-            ":" + data.children.collect {|i| format_internal(i).join(",")}
-        end
-      end
-
-      def validate_internal(data)
-        case data
-        when "*"
-        when Integer
-          ensure_nz_number(data)
-        when Range
-        when Array
-          data.each do |i|
-            validate_internal(i)
-          end
-        when ThreadMember
-          data.children.each do |i|
-            validate_internal(i)
-          end
-        else
-          raise DataFormatError, data.inspect
-        end
-      end
-
-      def ensure_nz_number(num)
-        if num < -1 || num == 0 || num >= 4294967296
-          msg = "nz_number must be non-zero unsigned 32-bit integer: " +
-                num.inspect
-          raise DataFormatError, msg
-        end
-      end
-    end
-
-    # Net::IMAP::ContinuationRequest represents command continuation requests.
-    #
-    # The command continuation request response is indicated by a "+" token
-    # instead of a tag.  This form of response indicates that the server is
-    # ready to accept the continuation of a command from the client.  The
-    # remainder of this response is a line of text.
-    #
-    #   continue_req    ::= "+" SPACE (resp_text / base64)
-    #
-    # ==== Fields:
-    #
-    # data:: Returns the data (Net::IMAP::ResponseText).
-    #
-    # raw_data:: Returns the raw data string.
-    ContinuationRequest = Struct.new(:data, :raw_data)
-
-    # Net::IMAP::UntaggedResponse represents untagged responses.
-    #
-    # Data transmitted by the server to the client and status responses
-    # that do not indicate command completion are prefixed with the token
-    # "*", and are called untagged responses.
-    #
-    #   response_data   ::= "*" SPACE (resp_cond_state / resp_cond_bye /
-    #                       mailbox_data / message_data / capability_data)
-    #
-    # ==== Fields:
-    #
-    # name:: Returns the name such as "FLAGS", "LIST", "FETCH"....
-    #
-    # data:: Returns the data such as an array of flag symbols,
-    #         a ((<Net::IMAP::MailboxList>)) object....
-    #
-    # raw_data:: Returns the raw data string.
-    UntaggedResponse = Struct.new(:name, :data, :raw_data)
-
-    # Net::IMAP::TaggedResponse represents tagged responses.
-    #
-    # The server completion result response indicates the success or
-    # failure of the operation.  It is tagged with the same tag as the
-    # client command which began the operation.
-    #
-    #   response_tagged ::= tag SPACE resp_cond_state CRLF
-    #
-    #   tag             ::= 1*<any ATOM_CHAR except "+">
-    #
-    #   resp_cond_state ::= ("OK" / "NO" / "BAD") SPACE resp_text
-    #
-    # ==== Fields:
-    #
-    # tag:: Returns the tag.
-    #
-    # name:: Returns the name. the name is one of "OK", "NO", "BAD".
-    #
-    # data:: Returns the data. See ((<Net::IMAP::ResponseText>)).
-    #
-    # raw_data:: Returns the raw data string.
-    #
-    TaggedResponse = Struct.new(:tag, :name, :data, :raw_data)
-
-    # Net::IMAP::ResponseText represents texts of responses.
-    # The text may be prefixed by the response code.
-    #
-    #   resp_text       ::= ["[" resp_text_code "]" SPACE] (text_mime2 / text)
-    #                       ;; text SHOULD NOT begin with "[" or "="
-    #
-    # ==== Fields:
-    #
-    # code:: Returns the response code. See ((<Net::IMAP::ResponseCode>)).
-    #
-    # text:: Returns the text.
-    #
-    ResponseText = Struct.new(:code, :text)
-
-    #
-    # Net::IMAP::ResponseCode represents response codes.
-    #
-    #   resp_text_code  ::= "ALERT" / "PARSE" /
-    #                       "PERMANENTFLAGS" SPACE "(" #(flag / "\*") ")" /
-    #                       "READ-ONLY" / "READ-WRITE" / "TRYCREATE" /
-    #                       "UIDVALIDITY" SPACE nz_number /
-    #                       "UNSEEN" SPACE nz_number /
-    #                       atom [SPACE 1*<any TEXT_CHAR except "]">]
-    #
-    # ==== Fields:
-    #
-    # name:: Returns the name such as "ALERT", "PERMANENTFLAGS", "UIDVALIDITY"....
-    #
-    # data:: Returns the data if it exists.
-    #
-    ResponseCode = Struct.new(:name, :data)
-
-    # Net::IMAP::MailboxList represents contents of the LIST response.
-    #
-    #   mailbox_list    ::= "(" #("\Marked" / "\Noinferiors" /
-    #                       "\Noselect" / "\Unmarked" / flag_extension) ")"
-    #                       SPACE (<"> QUOTED_CHAR <"> / nil) SPACE mailbox
-    #
-    # ==== Fields:
-    #
-    # attr:: Returns the name attributes. Each name attribute is a symbol
-    #        capitalized by String#capitalize, such as :Noselect (not :NoSelect).
-    #
-    # delim:: Returns the hierarchy delimiter
-    #
-    # name:: Returns the mailbox name.
-    #
-    MailboxList = Struct.new(:attr, :delim, :name)
-
-    # Net::IMAP::MailboxQuota represents contents of GETQUOTA response.
-    # This object can also be a response to GETQUOTAROOT.  In the syntax
-    # specification below, the delimiter used with the "#" construct is a
-    # single space (SPACE).
-    #
-    #    quota_list      ::= "(" #quota_resource ")"
-    #
-    #    quota_resource  ::= atom SPACE number SPACE number
-    #
-    #    quota_response  ::= "QUOTA" SPACE astring SPACE quota_list
-    #
-    # ==== Fields:
-    #
-    # mailbox:: The mailbox with the associated quota.
-    #
-    # usage:: Current storage usage of mailbox.
-    #
-    # quota:: Quota limit imposed on mailbox.
-    #
-    MailboxQuota = Struct.new(:mailbox, :usage, :quota)
-
-    # Net::IMAP::MailboxQuotaRoot represents part of the GETQUOTAROOT
-    # response. (GETQUOTAROOT can also return Net::IMAP::MailboxQuota.)
-    #
-    #    quotaroot_response ::= "QUOTAROOT" SPACE astring *(SPACE astring)
-    #
-    # ==== Fields:
-    #
-    # mailbox:: The mailbox with the associated quota.
-    #
-    # quotaroots:: Zero or more quotaroots that effect the quota on the
-    #              specified mailbox.
-    #
-    MailboxQuotaRoot = Struct.new(:mailbox, :quotaroots)
-
-    # Net::IMAP::MailboxACLItem represents response from GETACL.
-    #
-    #    acl_data        ::= "ACL" SPACE mailbox *(SPACE identifier SPACE rights)
-    #
-    #    identifier      ::= astring
-    #
-    #    rights          ::= astring
-    #
-    # ==== Fields:
-    #
-    # user:: Login name that has certain rights to the mailbox
-    #        that was specified with the getacl command.
-    #
-    # rights:: The access rights the indicated user has to the
-    #          mailbox.
-    #
-    MailboxACLItem = Struct.new(:user, :rights, :mailbox)
-
-    # Net::IMAP::StatusData represents contents of the STATUS response.
-    #
-    # ==== Fields:
-    #
-    # mailbox:: Returns the mailbox name.
-    #
-    # attr:: Returns a hash. Each key is one of "MESSAGES", "RECENT", "UIDNEXT",
-    #        "UIDVALIDITY", "UNSEEN". Each value is a number.
-    #
-    StatusData = Struct.new(:mailbox, :attr)
-
-    # Net::IMAP::FetchData represents contents of the FETCH response.
-    #
-    # ==== Fields:
-    #
-    # seqno:: Returns the message sequence number.
-    #         (Note: not the unique identifier, even for the UID command response.)
-    #
-    # attr:: Returns a hash. Each key is a data item name, and each value is
-    #        its value.
-    #
-    #        The current data items are:
-    #
-    #        [BODY]
-    #           A form of BODYSTRUCTURE without extension data.
-    #        [BODY[<section>]<<origin_octet>>]
-    #           A string expressing the body contents of the specified section.
-    #        [BODYSTRUCTURE]
-    #           An object that describes the [MIME-IMB] body structure of a message.
-    #           See Net::IMAP::BodyTypeBasic, Net::IMAP::BodyTypeText,
-    #           Net::IMAP::BodyTypeMessage, Net::IMAP::BodyTypeMultipart.
-    #        [ENVELOPE]
-    #           A Net::IMAP::Envelope object that describes the envelope
-    #           structure of a message.
-    #        [FLAGS]
-    #           A array of flag symbols that are set for this message. flag symbols
-    #           are capitalized by String#capitalize.
-    #        [INTERNALDATE]
-    #           A string representing the internal date of the message.
-    #        [RFC822]
-    #           Equivalent to BODY[].
-    #        [RFC822.HEADER]
-    #           Equivalent to BODY.PEEK[HEADER].
-    #        [RFC822.SIZE]
-    #           A number expressing the [RFC-822] size of the message.
-    #        [RFC822.TEXT]
-    #           Equivalent to BODY[TEXT].
-    #        [UID]
-    #           A number expressing the unique identifier of the message.
-    #
-    FetchData = Struct.new(:seqno, :attr)
-
-    # Net::IMAP::Envelope represents envelope structures of messages.
-    #
-    # ==== Fields:
-    #
-    # date:: Returns a string that represents the date.
-    #
-    # subject:: Returns a string that represents the subject.
-    #
-    # from:: Returns an array of Net::IMAP::Address that represents the from.
-    #
-    # sender:: Returns an array of Net::IMAP::Address that represents the sender.
-    #
-    # reply_to:: Returns an array of Net::IMAP::Address that represents the reply-to.
-    #
-    # to:: Returns an array of Net::IMAP::Address that represents the to.
-    #
-    # cc:: Returns an array of Net::IMAP::Address that represents the cc.
-    #
-    # bcc:: Returns an array of Net::IMAP::Address that represents the bcc.
-    #
-    # in_reply_to:: Returns a string that represents the in-reply-to.
-    #
-    # message_id:: Returns a string that represents the message-id.
-    #
-    Envelope = Struct.new(:date, :subject, :from, :sender, :reply_to,
-                          :to, :cc, :bcc, :in_reply_to, :message_id)
-
-    #
-    # Net::IMAP::Address represents electronic mail addresses.
-    #
-    # ==== Fields:
-    #
-    # name:: Returns the phrase from [RFC-822] mailbox.
-    #
-    # route:: Returns the route from [RFC-822] route-addr.
-    #
-    # mailbox:: nil indicates end of [RFC-822] group.
-    #           If non-nil and host is nil, returns [RFC-822] group name.
-    #           Otherwise, returns [RFC-822] local-part
-    #
-    # host:: nil indicates [RFC-822] group syntax.
-    #        Otherwise, returns [RFC-822] domain name.
-    #
-    Address = Struct.new(:name, :route, :mailbox, :host)
-
-    #
-    # Net::IMAP::ContentDisposition represents Content-Disposition fields.
-    #
-    # ==== Fields:
-    #
-    # dsp_type:: Returns the disposition type.
-    #
-    # param:: Returns a hash that represents parameters of the Content-Disposition
-    #         field.
-    #
-    ContentDisposition = Struct.new(:dsp_type, :param)
-
-    # Net::IMAP::ThreadMember represents a thread-node returned
-    # by Net::IMAP#thread
-    #
-    # ==== Fields:
-    #
-    # seqno:: The sequence number of this message.
-    #
-    # children:: an array of Net::IMAP::ThreadMember objects for mail
-    # items that are children of this in the thread.
-    #
-    ThreadMember = Struct.new(:seqno, :children)
-
-    # Net::IMAP::BodyTypeBasic represents basic body structures of messages.
-    #
-    # ==== Fields:
-    #
-    # media_type:: Returns the content media type name as defined in [MIME-IMB].
-    #
-    # subtype:: Returns the content subtype name as defined in [MIME-IMB].
-    #
-    # param:: Returns a hash that represents parameters as defined in [MIME-IMB].
-    #
-    # content_id:: Returns a string giving the content id as defined in [MIME-IMB].
-    #
-    # description:: Returns a string giving the content description as defined in
-    #               [MIME-IMB].
-    #
-    # encoding:: Returns a string giving the content transfer encoding as defined in
-    #            [MIME-IMB].
-    #
-    # size:: Returns a number giving the size of the body in octets.
-    #
-    # md5:: Returns a string giving the body MD5 value as defined in [MD5].
-    #
-    # disposition:: Returns a Net::IMAP::ContentDisposition object giving
-    #               the content disposition.
-    #
-    # language:: Returns a string or an array of strings giving the body
-    #            language value as defined in [LANGUAGE-TAGS].
-    #
-    # extension:: Returns extension data.
-    #
-    # multipart?:: Returns false.
-    #
-    class BodyTypeBasic < Struct.new(:media_type, :subtype,
-                                     :param, :content_id,
-                                     :description, :encoding, :size,
-                                     :md5, :disposition, :language,
-                                     :extension)
-      def multipart?
-        return false
-      end
-
-      # Obsolete: use +subtype+ instead.  Calling this will
-      # generate a warning message to +stderr+, then return
-      # the value of +subtype+.
-      def media_subtype
-        $stderr.printf("warning: media_subtype is obsolete.\n")
-        $stderr.printf("         use subtype instead.\n")
-        return subtype
-      end
-    end
-
-    # Net::IMAP::BodyTypeText represents TEXT body structures of messages.
-    #
-    # ==== Fields:
-    #
-    # lines:: Returns the size of the body in text lines.
-    #
-    # And Net::IMAP::BodyTypeText has all fields of Net::IMAP::BodyTypeBasic.
-    #
-    class BodyTypeText < Struct.new(:media_type, :subtype,
-                                    :param, :content_id,
-                                    :description, :encoding, :size,
-                                    :lines,
-                                    :md5, :disposition, :language,
-                                    :extension)
-      def multipart?
-        return false
-      end
-
-      # Obsolete: use +subtype+ instead.  Calling this will
-      # generate a warning message to +stderr+, then return
-      # the value of +subtype+.
-      def media_subtype
-        $stderr.printf("warning: media_subtype is obsolete.\n")
-        $stderr.printf("         use subtype instead.\n")
-        return subtype
-      end
-    end
-
-    # Net::IMAP::BodyTypeMessage represents MESSAGE/RFC822 body structures of messages.
-    #
-    # ==== Fields:
-    #
-    # envelope:: Returns a Net::IMAP::Envelope giving the envelope structure.
-    #
-    # body:: Returns an object giving the body structure.
-    #
-    # And Net::IMAP::BodyTypeMessage has all methods of Net::IMAP::BodyTypeText.
-    #
-    class BodyTypeMessage < Struct.new(:media_type, :subtype,
-                                       :param, :content_id,
-                                       :description, :encoding, :size,
-                                       :envelope, :body, :lines,
-                                       :md5, :disposition, :language,
-                                       :extension)
-      def multipart?
-        return false
-      end
-
-      # Obsolete: use +subtype+ instead.  Calling this will
-      # generate a warning message to +stderr+, then return
-      # the value of +subtype+.
-      def media_subtype
-        $stderr.printf("warning: media_subtype is obsolete.\n")
-        $stderr.printf("         use subtype instead.\n")
-        return subtype
-      end
-    end
-
-    # Net::IMAP::BodyTypeMultipart represents multipart body structures
-    # of messages.
-    #
-    # ==== Fields:
-    #
-    # media_type:: Returns the content media type name as defined in [MIME-IMB].
-    #
-    # subtype:: Returns the content subtype name as defined in [MIME-IMB].
-    #
-    # parts:: Returns multiple parts.
-    #
-    # param:: Returns a hash that represents parameters as defined in [MIME-IMB].
-    #
-    # disposition:: Returns a Net::IMAP::ContentDisposition object giving
-    #               the content disposition.
-    #
-    # language:: Returns a string or an array of strings giving the body
-    #            language value as defined in [LANGUAGE-TAGS].
-    #
-    # extension:: Returns extension data.
-    #
-    # multipart?:: Returns true.
-    #
-    class BodyTypeMultipart < Struct.new(:media_type, :subtype,
-                                         :parts,
-                                         :param, :disposition, :language,
-                                         :extension)
-      def multipart?
-        return true
-      end
-
-      # Obsolete: use +subtype+ instead.  Calling this will
-      # generate a warning message to +stderr+, then return
-      # the value of +subtype+.
-      def media_subtype
-        $stderr.printf("warning: media_subtype is obsolete.\n")
-        $stderr.printf("         use subtype instead.\n")
-        return subtype
-      end
-    end
-
-    class ResponseParser # :nodoc:
-      def initialize
-        @str = nil
-        @pos = nil
-        @lex_state = nil
-        @token = nil
-        @flag_symbols = {}
-      end
-
-      def parse(str)
-        @str = str
-        @pos = 0
-        @lex_state = EXPR_BEG
-        @token = nil
-        return response
-      end
-
-      private
-
-      EXPR_BEG          = :EXPR_BEG
-      EXPR_DATA         = :EXPR_DATA
-      EXPR_TEXT         = :EXPR_TEXT
-      EXPR_RTEXT        = :EXPR_RTEXT
-      EXPR_CTEXT        = :EXPR_CTEXT
-
-      T_SPACE   = :SPACE
-      T_NIL     = :NIL
-      T_NUMBER  = :NUMBER
-      T_ATOM    = :ATOM
-      T_QUOTED  = :QUOTED
-      T_LPAR    = :LPAR
-      T_RPAR    = :RPAR
-      T_BSLASH  = :BSLASH
-      T_STAR    = :STAR
-      T_LBRA    = :LBRA
-      T_RBRA    = :RBRA
-      T_LITERAL = :LITERAL
-      T_PLUS    = :PLUS
-      T_PERCENT = :PERCENT
-      T_CRLF    = :CRLF
-      T_EOF     = :EOF
-      T_TEXT    = :TEXT
-
-      BEG_REGEXP = /\G(?:\
-(?# 1:  SPACE   )( +)|\
-(?# 2:  NIL     )(NIL)(?=[\x80-\xff(){ \x00-\x1f\x7f%*#{'"'}\\\[\]+])|\
-(?# 3:  NUMBER  )(\d+)(?=[\x80-\xff(){ \x00-\x1f\x7f%*#{'"'}\\\[\]+])|\
-(?# 4:  ATOM    )([^\x80-\xff(){ \x00-\x1f\x7f%*#{'"'}\\\[\]+]+)|\
-(?# 5:  QUOTED  )"((?:[^\x00\r\n"\\]|\\["\\])*)"|\
-(?# 6:  LPAR    )(\()|\
-(?# 7:  RPAR    )(\))|\
-(?# 8:  BSLASH  )(\\)|\
-(?# 9:  STAR    )(\*)|\
-(?# 10: LBRA    )(\[)|\
-(?# 11: RBRA    )(\])|\
-(?# 12: LITERAL )\{(\d+)\}\r\n|\
-(?# 13: PLUS    )(\+)|\
-(?# 14: PERCENT )(%)|\
-(?# 15: CRLF    )(\r\n)|\
-(?# 16: EOF     )(\z))/ni
-
-      DATA_REGEXP = /\G(?:\
-(?# 1:  SPACE   )( )|\
-(?# 2:  NIL     )(NIL)|\
-(?# 3:  NUMBER  )(\d+)|\
-(?# 4:  QUOTED  )"((?:[^\x00\r\n"\\]|\\["\\])*)"|\
-(?# 5:  LITERAL )\{(\d+)\}\r\n|\
-(?# 6:  LPAR    )(\()|\
-(?# 7:  RPAR    )(\)))/ni
-
-      TEXT_REGEXP = /\G(?:\
-(?# 1:  TEXT    )([^\x00\r\n]*))/ni
-
-      RTEXT_REGEXP = /\G(?:\
-(?# 1:  LBRA    )(\[)|\
-(?# 2:  TEXT    )([^\x00\r\n]*))/ni
-
-      CTEXT_REGEXP = /\G(?:\
-(?# 1:  TEXT    )([^\x00\r\n\]]*))/ni
-
-      Token = Struct.new(:symbol, :value)
-
-      def response
-        token = lookahead
-        case token.symbol
-        when T_PLUS
-          result = continue_req
-        when T_STAR
-          result = response_untagged
-        else
-          result = response_tagged
-        end
-        match(T_CRLF)
-        match(T_EOF)
-        return result
-      end
-
-      def continue_req
-        match(T_PLUS)
-        match(T_SPACE)
-        return ContinuationRequest.new(resp_text, @str)
-      end
-
-      def response_untagged
-        match(T_STAR)
-        match(T_SPACE)
-        token = lookahead
-        if token.symbol == T_NUMBER
-          return numeric_response
-        elsif token.symbol == T_ATOM
-          case token.value
-          when /\A(?:OK|NO|BAD|BYE|PREAUTH)\z/ni
-            return response_cond
-          when /\A(?:FLAGS)\z/ni
-            return flags_response
-          when /\A(?:LIST|LSUB|XLIST)\z/ni
-            return list_response
-          when /\A(?:QUOTA)\z/ni
-            return getquota_response
-          when /\A(?:QUOTAROOT)\z/ni
-            return getquotaroot_response
-          when /\A(?:ACL)\z/ni
-            return getacl_response
-          when /\A(?:SEARCH|SORT)\z/ni
-            return search_response
-          when /\A(?:THREAD)\z/ni
-            return thread_response
-          when /\A(?:STATUS)\z/ni
-            return status_response
-          when /\A(?:CAPABILITY)\z/ni
-            return capability_response
-          else
-            return text_response
-          end
-        else
-          parse_error("unexpected token %s", token.symbol)
-        end
-      end
-
-      def response_tagged
-        tag = atom
-        match(T_SPACE)
-        token = match(T_ATOM)
-        name = token.value.upcase
-        match(T_SPACE)
-        return TaggedResponse.new(tag, name, resp_text, @str)
-      end
-
-      def response_cond
-        token = match(T_ATOM)
-        name = token.value.upcase
-        match(T_SPACE)
-        return UntaggedResponse.new(name, resp_text, @str)
-      end
-
-      def numeric_response
-        n = number
-        match(T_SPACE)
-        token = match(T_ATOM)
-        name = token.value.upcase
-        case name
-        when "EXISTS", "RECENT", "EXPUNGE"
-          return UntaggedResponse.new(name, n, @str)
-        when "FETCH"
-          shift_token
-          match(T_SPACE)
-          data = FetchData.new(n, msg_att)
-          return UntaggedResponse.new(name, data, @str)
-        end
-      end
-
-      def msg_att
-        match(T_LPAR)
-        attr = {}
-        while true
-          token = lookahead
-          case token.symbol
-          when T_RPAR
-            shift_token
-            break
-          when T_SPACE
-            shift_token
-            next
-          end
-          case token.value
-          when /\A(?:ENVELOPE)\z/ni
-            name, val = envelope_data
-          when /\A(?:FLAGS)\z/ni
-            name, val = flags_data
-          when /\A(?:INTERNALDATE)\z/ni
-            name, val = internaldate_data
-          when /\A(?:RFC822(?:\.HEADER|\.TEXT)?)\z/ni
-            name, val = rfc822_text
-          when /\A(?:RFC822\.SIZE)\z/ni
-            name, val = rfc822_size
-          when /\A(?:BODY(?:STRUCTURE)?)\z/ni
-            name, val = body_data
-          when /\A(?:UID)\z/ni
-            name, val = uid_data
-          else
-            parse_error("unknown attribute `%s'", token.value)
-          end
-          attr[name] = val
-        end
-        return attr
-      end
-
-      def envelope_data
-        token = match(T_ATOM)
-        name = token.value.upcase
-        match(T_SPACE)
-        return name, envelope
-      end
-
-      def envelope
-        @lex_state = EXPR_DATA
-        token = lookahead
-        if token.symbol == T_NIL
-          shift_token
-          result = nil
-        else
-          match(T_LPAR)
-          date = nstring
-          match(T_SPACE)
-          subject = nstring
-          match(T_SPACE)
-          from = address_list
-          match(T_SPACE)
-          sender = address_list
-          match(T_SPACE)
-          reply_to = address_list
-          match(T_SPACE)
-          to = address_list
-          match(T_SPACE)
-          cc = address_list
-          match(T_SPACE)
-          bcc = address_list
-          match(T_SPACE)
-          in_reply_to = nstring
-          match(T_SPACE)
-          message_id = nstring
-          match(T_RPAR)
-          result = Envelope.new(date, subject, from, sender, reply_to,
-                                to, cc, bcc, in_reply_to, message_id)
-        end
-        @lex_state = EXPR_BEG
-        return result
-      end
-
-      def flags_data
-        token = match(T_ATOM)
-        name = token.value.upcase
-        match(T_SPACE)
-        return name, flag_list
-      end
-
-      def internaldate_data
-        token = match(T_ATOM)
-        name = token.value.upcase
-        match(T_SPACE)
-        token = match(T_QUOTED)
-        return name, token.value
-      end
-
-      def rfc822_text
-        token = match(T_ATOM)
-        name = token.value.upcase
-        match(T_SPACE)
-        return name, nstring
-      end
-
-      def rfc822_size
-        token = match(T_ATOM)
-        name = token.value.upcase
-        match(T_SPACE)
-        return name, number
-      end
-
-      def body_data
-        token = match(T_ATOM)
-        name = token.value.upcase
-        token = lookahead
-        if token.symbol == T_SPACE
-          shift_token
-          return name, body
-        end
-        name.concat(section)
-        token = lookahead
-        if token.symbol == T_ATOM
-          name.concat(token.value)
-          shift_token
-        end
-        match(T_SPACE)
-        data = nstring
-        return name, data
-      end
-
-      def body
-        @lex_state = EXPR_DATA
-        token = lookahead
-        if token.symbol == T_NIL
-          shift_token
-          result = nil
-        else
-          match(T_LPAR)
-          token = lookahead
-          if token.symbol == T_LPAR
-            result = body_type_mpart
-          else
-            result = body_type_1part
-          end
-          match(T_RPAR)
-        end
-        @lex_state = EXPR_BEG
-        return result
-      end
-
-      def body_type_1part
-        token = lookahead
-        case token.value
-        when /\A(?:TEXT)\z/ni
-          return body_type_text
-        when /\A(?:MESSAGE)\z/ni
-          return body_type_msg
-        else
-          return body_type_basic
-        end
-      end
-
-      def body_type_basic
-        mtype, msubtype = media_type
-        token = lookahead
-        if token.symbol == T_RPAR
-          return BodyTypeBasic.new(mtype, msubtype)
-        end
-        match(T_SPACE)
-        param, content_id, desc, enc, size = body_fields
-        md5, disposition, language, extension = body_ext_1part
-        return BodyTypeBasic.new(mtype, msubtype,
-                                 param, content_id,
-                                 desc, enc, size,
-                                 md5, disposition, language, extension)
-      end
-
-      def body_type_text
-        mtype, msubtype = media_type
-        match(T_SPACE)
-        param, content_id, desc, enc, size = body_fields
-        match(T_SPACE)
-        lines = number
-        md5, disposition, language, extension = body_ext_1part
-        return BodyTypeText.new(mtype, msubtype,
-                                param, content_id,
-                                desc, enc, size,
-                                lines,
-                                md5, disposition, language, extension)
-      end
-
-      def body_type_msg
-        mtype, msubtype = media_type
-        match(T_SPACE)
-        param, content_id, desc, enc, size = body_fields
-        match(T_SPACE)
-        env = envelope
-        match(T_SPACE)
-        b = body
-        match(T_SPACE)
-        lines = number
-        md5, disposition, language, extension = body_ext_1part
-        return BodyTypeMessage.new(mtype, msubtype,
-                                   param, content_id,
-                                   desc, enc, size,
-                                   env, b, lines,
-                                   md5, disposition, language, extension)
-      end
-
-      def body_type_mpart
-        parts = []
-        while true
-          token = lookahead
-          if token.symbol == T_SPACE
-            shift_token
-            break
-          end
-          parts.push(body)
-        end
-        mtype = "MULTIPART"
-        msubtype = case_insensitive_string
-        param, disposition, language, extension = body_ext_mpart
-        return BodyTypeMultipart.new(mtype, msubtype, parts,
-                                     param, disposition, language,
-                                     extension)
-      end
-
-      def media_type
-        mtype = case_insensitive_string
-        match(T_SPACE)
-        msubtype = case_insensitive_string
-        return mtype, msubtype
-      end
-
-      def body_fields
-        param = body_fld_param
-        match(T_SPACE)
-        content_id = nstring
-        match(T_SPACE)
-        desc = nstring
-        match(T_SPACE)
-        enc = case_insensitive_string
-        match(T_SPACE)
-        size = number
-        return param, content_id, desc, enc, size
-      end
-
-      def body_fld_param
-        token = lookahead
-        if token.symbol == T_NIL
-          shift_token
-          return nil
-        end
-        match(T_LPAR)
-        param = {}
-        while true
-          token = lookahead
-          case token.symbol
-          when T_RPAR
-            shift_token
-            break
-          when T_SPACE
-            shift_token
-          end
-          name = case_insensitive_string
-          match(T_SPACE)
-          val = string
-          param[name] = val
-        end
-        return param
-      end
-
-      def body_ext_1part
-        token = lookahead
-        if token.symbol == T_SPACE
-          shift_token
-        else
-          return nil
-        end
-        md5 = nstring
-
-        token = lookahead
-        if token.symbol == T_SPACE
-          shift_token
-        else
-          return md5
-        end
-        disposition = body_fld_dsp
-
-        token = lookahead
-        if token.symbol == T_SPACE
-          shift_token
-        else
-          return md5, disposition
-        end
-        language = body_fld_lang
-
-        token = lookahead
-        if token.symbol == T_SPACE
-          shift_token
-        else
-          return md5, disposition, language
-        end
-
-        extension = body_extensions
-        return md5, disposition, language, extension
-      end
-
-      def body_ext_mpart
-        token = lookahead
-        if token.symbol == T_SPACE
-          shift_token
-        else
-          return nil
-        end
-        param = body_fld_param
-
-        token = lookahead
-        if token.symbol == T_SPACE
-          shift_token
-        else
-          return param
-        end
-        disposition = body_fld_dsp
-        match(T_SPACE)
-        language = body_fld_lang
-
-        token = lookahead
-        if token.symbol == T_SPACE
-          shift_token
-        else
-          return param, disposition, language
-        end
-
-        extension = body_extensions
-        return param, disposition, language, extension
-      end
-
-      def body_fld_dsp
-        token = lookahead
-        if token.symbol == T_NIL
-          shift_token
-          return nil
-        end
-        match(T_LPAR)
-        dsp_type = case_insensitive_string
-        match(T_SPACE)
-        param = body_fld_param
-        match(T_RPAR)
-        return ContentDisposition.new(dsp_type, param)
-      end
-
-      def body_fld_lang
-        token = lookahead
-        if token.symbol == T_LPAR
-          shift_token
-          result = []
-          while true
-            token = lookahead
-            case token.symbol
-            when T_RPAR
-              shift_token
-              return result
-            when T_SPACE
-              shift_token
-            end
-            result.push(case_insensitive_string)
-          end
-        else
-          lang = nstring
-          if lang
-            return lang.upcase
-          else
-            return lang
-          end
-        end
-      end
-
-      def body_extensions
-        result = []
-        while true
-          token = lookahead
-          case token.symbol
-          when T_RPAR
-            return result
-          when T_SPACE
-            shift_token
-          end
-          result.push(body_extension)
-        end
-      end
-
-      def body_extension
-        token = lookahead
-        case token.symbol
-        when T_LPAR
-          shift_token
-          result = body_extensions
-          match(T_RPAR)
-          return result
-        when T_NUMBER
-          return number
-        else
-          return nstring
-        end
-      end
-
-      def section
-        str = ""
-        token = match(T_LBRA)
-        str.concat(token.value)
-        token = match(T_ATOM, T_NUMBER, T_RBRA)
-        if token.symbol == T_RBRA
-          str.concat(token.value)
-          return str
-        end
-        str.concat(token.value)
-        token = lookahead
-        if token.symbol == T_SPACE
-          shift_token
-          str.concat(token.value)
-          token = match(T_LPAR)
-          str.concat(token.value)
-          while true
-            token = lookahead
-            case token.symbol
-            when T_RPAR
-              str.concat(token.value)
-              shift_token
-              break
-            when T_SPACE
-              shift_token
-              str.concat(token.value)
-            end
-            str.concat(format_string(astring))
-          end
-        end
-        token = match(T_RBRA)
-        str.concat(token.value)
-        return str
-      end
-
-      def format_string(str)
-        case str
-        when ""
-          return '""'
-        when /[\x80-\xff\r\n]/n
-          # literal
-          return "{" + str.bytesize.to_s + "}" + CRLF + str
-        when /[(){ \x00-\x1f\x7f%*"\\]/n
-          # quoted string
-          return '"' + str.gsub(/["\\]/n, "\\\\\\&") + '"'
-        else
-          # atom
-          return str
-        end
-      end
-
-      def uid_data
-        token = match(T_ATOM)
-        name = token.value.upcase
-        match(T_SPACE)
-        return name, number
-      end
-
-      def text_response
-        token = match(T_ATOM)
-        name = token.value.upcase
-        match(T_SPACE)
-        @lex_state = EXPR_TEXT
-        token = match(T_TEXT)
-        @lex_state = EXPR_BEG
-        return UntaggedResponse.new(name, token.value)
-      end
-
-      def flags_response
-        token = match(T_ATOM)
-        name = token.value.upcase
-        match(T_SPACE)
-        return UntaggedResponse.new(name, flag_list, @str)
-      end
-
-      def list_response
-        token = match(T_ATOM)
-        name = token.value.upcase
-        match(T_SPACE)
-        return UntaggedResponse.new(name, mailbox_list, @str)
-      end
-
-      def mailbox_list
-        attr = flag_list
-        match(T_SPACE)
-        token = match(T_QUOTED, T_NIL)
-        if token.symbol == T_NIL
-          delim = nil
-        else
-          delim = token.value
-        end
-        match(T_SPACE)
-        name = astring
-        return MailboxList.new(attr, delim, name)
-      end
-
-      def getquota_response
-        # If quota never established, get back
-        # `NO Quota root does not exist'.
-        # If quota removed, get `()' after the
-        # folder spec with no mention of `STORAGE'.
-        token = match(T_ATOM)
-        name = token.value.upcase
-        match(T_SPACE)
-        mailbox = astring
-        match(T_SPACE)
-        match(T_LPAR)
-        token = lookahead
-        case token.symbol
-        when T_RPAR
-          shift_token
-          data = MailboxQuota.new(mailbox, nil, nil)
-          return UntaggedResponse.new(name, data, @str)
-        when T_ATOM
-          shift_token
-          match(T_SPACE)
-          token = match(T_NUMBER)
-          usage = token.value
-          match(T_SPACE)
-          token = match(T_NUMBER)
-          quota = token.value
-          match(T_RPAR)
-          data = MailboxQuota.new(mailbox, usage, quota)
-          return UntaggedResponse.new(name, data, @str)
-        else
-          parse_error("unexpected token %s", token.symbol)
-        end
-      end
-
-      def getquotaroot_response
-        # Similar to getquota, but only admin can use getquota.
-        token = match(T_ATOM)
-        name = token.value.upcase
-        match(T_SPACE)
-        mailbox = astring
-        quotaroots = []
-        while true
-          token = lookahead
-          break unless token.symbol == T_SPACE
-          shift_token
-          quotaroots.push(astring)
-        end
-        data = MailboxQuotaRoot.new(mailbox, quotaroots)
-        return UntaggedResponse.new(name, data, @str)
-      end
-
-      def getacl_response
-        token = match(T_ATOM)
-        name = token.value.upcase
-        match(T_SPACE)
-        mailbox = astring
-        data = []
-        token = lookahead
-        if token.symbol == T_SPACE
-          shift_token
-          while true
-            token = lookahead
-            case token.symbol
-            when T_CRLF
-              break
-            when T_SPACE
-              shift_token
-            end
-            user = astring
-            match(T_SPACE)
-            rights = astring
-            data.push(MailboxACLItem.new(user, rights, mailbox))
-          end
-        end
-        return UntaggedResponse.new(name, data, @str)
-      end
-
-      def search_response
-        token = match(T_ATOM)
-        name = token.value.upcase
-        token = lookahead
-        if token.symbol == T_SPACE
-          shift_token
-          data = []
-          while true
-            token = lookahead
-            case token.symbol
-            when T_CRLF
-              break
-            when T_SPACE
-              shift_token
-            else
-              data.push(number)
-            end
-          end
-        else
-          data = []
-        end
-        return UntaggedResponse.new(name, data, @str)
-      end
-
-      def thread_response
-        token = match(T_ATOM)
-        name = token.value.upcase
-        token = lookahead
-
-        if token.symbol == T_SPACE
-          threads = []
-
-          while true
-            shift_token
-            token = lookahead
-
-            case token.symbol
-            when T_LPAR
-              threads << thread_branch(token)
-            when T_CRLF
-              break
-            end
-          end
-        else
-          # no member
-          threads = []
-        end
-
-        return UntaggedResponse.new(name, threads, @str)
-      end
-
-      def thread_branch(token)
-        rootmember = nil
-        lastmember = nil
-
-        while true
-          shift_token    # ignore first T_LPAR
-          token = lookahead
-
-          case token.symbol
-          when T_NUMBER
-            # new member
-            newmember = ThreadMember.new(number, [])
-            if rootmember.nil?
-              rootmember = newmember
-            else
-              lastmember.children << newmember
-            end
-            lastmember = newmember
-          when T_SPACE
-            # do nothing
-          when T_LPAR
-            if rootmember.nil?
-              # dummy member
-              lastmember = rootmember = ThreadMember.new(nil, [])
-            end
-
-            lastmember.children << thread_branch(token)
-          when T_RPAR
-            break
-          end
-        end
-
-        return rootmember
-      end
-
-      def status_response
-        token = match(T_ATOM)
-        name = token.value.upcase
-        match(T_SPACE)
-        mailbox = astring
-        match(T_SPACE)
-        match(T_LPAR)
-        attr = {}
-        while true
-          token = lookahead
-          case token.symbol
-          when T_RPAR
-            shift_token
-            break
-          when T_SPACE
-            shift_token
-          end
-          token = match(T_ATOM)
-          key = token.value.upcase
-          match(T_SPACE)
-          val = number
-          attr[key] = val
-        end
-        data = StatusData.new(mailbox, attr)
-        return UntaggedResponse.new(name, data, @str)
-      end
-
-      def capability_response
-        token = match(T_ATOM)
-        name = token.value.upcase
-        match(T_SPACE)
-        data = []
-        while true
-          token = lookahead
-          case token.symbol
-          when T_CRLF
-            break
-          when T_SPACE
-            shift_token
-            next
-          end
-          data.push(atom.upcase)
-        end
-        return UntaggedResponse.new(name, data, @str)
-      end
-
-      def resp_text
-        @lex_state = EXPR_RTEXT
-        token = lookahead
-        if token.symbol == T_LBRA
-          code = resp_text_code
-        else
-          code = nil
-        end
-        token = match(T_TEXT)
-        @lex_state = EXPR_BEG
-        return ResponseText.new(code, token.value)
-      end
-
-      def resp_text_code
-        @lex_state = EXPR_BEG
-        match(T_LBRA)
-        token = match(T_ATOM)
-        name = token.value.upcase
-        case name
-        when /\A(?:ALERT|PARSE|READ-ONLY|READ-WRITE|TRYCREATE|NOMODSEQ)\z/n
-          result = ResponseCode.new(name, nil)
-        when /\A(?:PERMANENTFLAGS)\z/n
-          match(T_SPACE)
-          result = ResponseCode.new(name, flag_list)
-        when /\A(?:UIDVALIDITY|UIDNEXT|UNSEEN)\z/n
-          match(T_SPACE)
-          result = ResponseCode.new(name, number)
-        else
-          token = lookahead
-          if token.symbol == T_SPACE
-            shift_token
-            @lex_state = EXPR_CTEXT
-            token = match(T_TEXT)
-            @lex_state = EXPR_BEG
-            result = ResponseCode.new(name, token.value)
-          else
-            result = ResponseCode.new(name, nil)
-          end
-        end
-        match(T_RBRA)
-        @lex_state = EXPR_RTEXT
-        return result
-      end
-
-      def address_list
-        token = lookahead
-        if token.symbol == T_NIL
-          shift_token
-          return nil
-        else
-          result = []
-          match(T_LPAR)
-          while true
-            token = lookahead
-            case token.symbol
-            when T_RPAR
-              shift_token
-              break
-            when T_SPACE
-              shift_token
-            end
-            result.push(address)
-          end
-          return result
-        end
-      end
-
-      ADDRESS_REGEXP = /\G\
-(?# 1: NAME     )(?:NIL|"((?:[^\x80-\xff\x00\r\n"\\]|\\["\\])*)") \
-(?# 2: ROUTE    )(?:NIL|"((?:[^\x80-\xff\x00\r\n"\\]|\\["\\])*)") \
-(?# 3: MAILBOX  )(?:NIL|"((?:[^\x80-\xff\x00\r\n"\\]|\\["\\])*)") \
-(?# 4: HOST     )(?:NIL|"((?:[^\x80-\xff\x00\r\n"\\]|\\["\\])*)")\
-\)/ni
-
-      def address
-        match(T_LPAR)
-        if @str.index(ADDRESS_REGEXP, @pos)
-          # address does not include literal.
-          @pos = $~.end(0)
-          name = $1
-          route = $2
-          mailbox = $3
-          host = $4
-          for s in [name, route, mailbox, host]
-            if s
-              s.gsub!(/\\(["\\])/n, "\\1")
-            end
-          end
-        else
-          name = nstring
-          match(T_SPACE)
-          route = nstring
-          match(T_SPACE)
-          mailbox = nstring
-          match(T_SPACE)
-          host = nstring
-          match(T_RPAR)
-        end
-        return Address.new(name, route, mailbox, host)
-      end
-
-#        def flag_list
-#       result = []
-#       match(T_LPAR)
-#       while true
-#         token = lookahead
-#         case token.symbol
-#         when T_RPAR
-#           shift_token
-#           break
-#         when T_SPACE
-#           shift_token
-#         end
-#         result.push(flag)
-#       end
-#       return result
-#        end
-
-#        def flag
-#       token = lookahead
-#       if token.symbol == T_BSLASH
-#         shift_token
-#         token = lookahead
-#         if token.symbol == T_STAR
-#           shift_token
-#           return token.value.intern
-#         else
-#           return atom.intern
-#         end
-#       else
-#         return atom
-#       end
-#        end
-
-      FLAG_REGEXP = /\
-(?# FLAG        )\\([^\x80-\xff(){ \x00-\x1f\x7f%"\\]+)|\
-(?# ATOM        )([^\x80-\xff(){ \x00-\x1f\x7f%*"\\]+)/n
-
-      def flag_list
-        if @str.index(/\(([^)]*)\)/ni, @pos)
-          @pos = $~.end(0)
-          return $1.scan(FLAG_REGEXP).collect { |flag, atom|
-            if atom
-              atom
-            else
-              symbol = flag.capitalize.untaint.intern
-              @flag_symbols[symbol] = true
-              if @flag_symbols.length > IMAP.max_flag_count
-                raise FlagCountError, "number of flag symbols exceeded"
-              end
-              symbol
-            end
-          }
-        else
-          parse_error("invalid flag list")
-        end
-      end
-
-      def nstring
-        token = lookahead
-        if token.symbol == T_NIL
-          shift_token
-          return nil
-        else
-          return string
-        end
-      end
-
-      def astring
-        token = lookahead
-        if string_token?(token)
-          return string
-        else
-          return atom
-        end
-      end
-
-      def string
-        token = lookahead
-        if token.symbol == T_NIL
-          shift_token
-          return nil
-        end
-        token = match(T_QUOTED, T_LITERAL)
-        return token.value
-      end
-
-      STRING_TOKENS = [T_QUOTED, T_LITERAL, T_NIL]
-
-      def string_token?(token)
-        return STRING_TOKENS.include?(token.symbol)
-      end
-
-      def case_insensitive_string
-        token = lookahead
-        if token.symbol == T_NIL
-          shift_token
-          return nil
-        end
-        token = match(T_QUOTED, T_LITERAL)
-        return token.value.upcase
-      end
-
-      def atom
-        result = ""
-        while true
-          token = lookahead
-          if atom_token?(token)
-            result.concat(token.value)
-            shift_token
-          else
-            if result.empty?
-              parse_error("unexpected token %s", token.symbol)
-            else
-              return result
-            end
-          end
-        end
-      end
-
-      ATOM_TOKENS = [
-        T_ATOM,
-        T_NUMBER,
-        T_NIL,
-        T_LBRA,
-        T_RBRA,
-        T_PLUS
-      ]
-
-      def atom_token?(token)
-        return ATOM_TOKENS.include?(token.symbol)
-      end
-
-      def number
-        token = lookahead
-        if token.symbol == T_NIL
-          shift_token
-          return nil
-        end
-        token = match(T_NUMBER)
-        return token.value.to_i
-      end
-
-      def nil_atom
-        match(T_NIL)
-        return nil
-      end
-
-      def match(*args)
-        token = lookahead
-        unless args.include?(token.symbol)
-          parse_error('unexpected token %s (expected %s)',
-                      token.symbol.id2name,
-                      args.collect {|i| i.id2name}.join(" or "))
-        end
-        shift_token
-        return token
-      end
-
-      def lookahead
-        unless @token
-          @token = next_token
-        end
-        return @token
-      end
-
-      def shift_token
-        @token = nil
-      end
-
-      def next_token
-        case @lex_state
-        when EXPR_BEG
-          if @str.index(BEG_REGEXP, @pos)
-            @pos = $~.end(0)
-            if $1
-              return Token.new(T_SPACE, $+)
-            elsif $2
-              return Token.new(T_NIL, $+)
-            elsif $3
-              return Token.new(T_NUMBER, $+)
-            elsif $4
-              return Token.new(T_ATOM, $+)
-            elsif $5
-              return Token.new(T_QUOTED,
-                               $+.gsub(/\\(["\\])/n, "\\1"))
-            elsif $6
-              return Token.new(T_LPAR, $+)
-            elsif $7
-              return Token.new(T_RPAR, $+)
-            elsif $8
-              return Token.new(T_BSLASH, $+)
-            elsif $9
-              return Token.new(T_STAR, $+)
-            elsif $10
-              return Token.new(T_LBRA, $+)
-            elsif $11
-              return Token.new(T_RBRA, $+)
-            elsif $12
-              len = $+.to_i
-              val = @str[@pos, len]
-              @pos += len
-              return Token.new(T_LITERAL, val)
-            elsif $13
-              return Token.new(T_PLUS, $+)
-            elsif $14
-              return Token.new(T_PERCENT, $+)
-            elsif $15
-              return Token.new(T_CRLF, $+)
-            elsif $16
-              return Token.new(T_EOF, $+)
-            else
-              parse_error("[Net::IMAP BUG] BEG_REGEXP is invalid")
-            end
-          else
-            @str.index(/\S*/n, @pos)
-            parse_error("unknown token - %s", $&.dump)
-          end
-        when EXPR_DATA
-          if @str.index(DATA_REGEXP, @pos)
-            @pos = $~.end(0)
-            if $1
-              return Token.new(T_SPACE, $+)
-            elsif $2
-              return Token.new(T_NIL, $+)
-            elsif $3
-              return Token.new(T_NUMBER, $+)
-            elsif $4
-              return Token.new(T_QUOTED,
-                               $+.gsub(/\\(["\\])/n, "\\1"))
-            elsif $5
-              len = $+.to_i
-              val = @str[@pos, len]
-              @pos += len
-              return Token.new(T_LITERAL, val)
-            elsif $6
-              return Token.new(T_LPAR, $+)
-            elsif $7
-              return Token.new(T_RPAR, $+)
-            else
-              parse_error("[Net::IMAP BUG] DATA_REGEXP is invalid")
-            end
-          else
-            @str.index(/\S*/n, @pos)
-            parse_error("unknown token - %s", $&.dump)
-          end
-        when EXPR_TEXT
-          if @str.index(TEXT_REGEXP, @pos)
-            @pos = $~.end(0)
-            if $1
-              return Token.new(T_TEXT, $+)
-            else
-              parse_error("[Net::IMAP BUG] TEXT_REGEXP is invalid")
-            end
-          else
-            @str.index(/\S*/n, @pos)
-            parse_error("unknown token - %s", $&.dump)
-          end
-        when EXPR_RTEXT
-          if @str.index(RTEXT_REGEXP, @pos)
-            @pos = $~.end(0)
-            if $1
-              return Token.new(T_LBRA, $+)
-            elsif $2
-              return Token.new(T_TEXT, $+)
-            else
-              parse_error("[Net::IMAP BUG] RTEXT_REGEXP is invalid")
-            end
-          else
-            @str.index(/\S*/n, @pos)
-            parse_error("unknown token - %s", $&.dump)
-          end
-        when EXPR_CTEXT
-          if @str.index(CTEXT_REGEXP, @pos)
-            @pos = $~.end(0)
-            if $1
-              return Token.new(T_TEXT, $+)
-            else
-              parse_error("[Net::IMAP BUG] CTEXT_REGEXP is invalid")
-            end
-          else
-            @str.index(/\S*/n, @pos) #/
-            parse_error("unknown token - %s", $&.dump)
-          end
-        else
-          parse_error("invalid @lex_state - %s", @lex_state.inspect)
-        end
-      end
-
-      def parse_error(fmt, *args)
-        if IMAP.debug
-          $stderr.printf("@str: %s\n", @str.dump)
-          $stderr.printf("@pos: %d\n", @pos)
-          $stderr.printf("@lex_state: %s\n", @lex_state)
-          if @token
-            $stderr.printf("@token.symbol: %s\n", @token.symbol)
-            $stderr.printf("@token.value: %s\n", @token.value.inspect)
-          end
-        end
-        raise ResponseParseError, format(fmt, *args)
-      end
-    end
-
-    # Authenticator for the "LOGIN" authentication type.  See
-    # #authenticate().
-    class LoginAuthenticator
-      def process(data)
-        case @state
-        when STATE_USER
-          @state = STATE_PASSWORD
-          return @user
-        when STATE_PASSWORD
-          return @password
-        end
-      end
-
-      private
-
-      STATE_USER = :USER
-      STATE_PASSWORD = :PASSWORD
-
-      def initialize(user, password)
-        @user = user
-        @password = password
-        @state = STATE_USER
-      end
-    end
-    add_authenticator "LOGIN", LoginAuthenticator
-
-    # Authenticator for the "PLAIN" authentication type.  See
-    # #authenticate().
-    class PlainAuthenticator
-      def process(data)
-        return "\0#{@user}\0#{@password}"
-      end
-
-      private
-
-      def initialize(user, password)
-        @user = user
-        @password = password
-      end
-    end
-    add_authenticator "PLAIN", PlainAuthenticator
-
-    # Authenticator for the "CRAM-MD5" authentication type.  See
-    # #authenticate().
-    class CramMD5Authenticator
-      def process(challenge)
-        digest = hmac_md5(challenge, @password)
-        return @user + " " + digest
-      end
-
-      private
-
-      def initialize(user, password)
-        @user = user
-        @password = password
-      end
-
-      def hmac_md5(text, key)
-        if key.length > 64
-          key = Digest::MD5.digest(key)
-        end
-
-        k_ipad = key + "\0" * (64 - key.length)
-        k_opad = key + "\0" * (64 - key.length)
-        for i in 0..63
-          k_ipad[i] = (k_ipad[i].ord ^ 0x36).chr
-          k_opad[i] = (k_opad[i].ord ^ 0x5c).chr
-        end
-
-        digest = Digest::MD5.digest(k_ipad + text)
-
-        return Digest::MD5.hexdigest(k_opad + digest)
-      end
-    end
-    add_authenticator "CRAM-MD5", CramMD5Authenticator
-
-    # Authenticator for the "DIGEST-MD5" authentication type.  See
-    # #authenticate().
-    class DigestMD5Authenticator
-      def process(challenge)
-        case @stage
-        when STAGE_ONE
-          @stage = STAGE_TWO
-          sparams = {}
-          c = StringScanner.new(challenge)
-          while c.scan(/(?:\s*,)?\s*(\w+)=("(?:[^\\"]+|\\.)*"|[^,]+)\s*/)
-            k, v = c[1], c[2]
-            if v =~ /^"(.*)"$/
-              v = $1
-              if v =~ /,/
-                v = v.split(',')
-              end
-            end
-            sparams[k] = v
-          end
-
-          raise DataFormatError, "Bad Challenge: '#{challenge}'" unless c.rest.size == 0
-          raise Error, "Server does not support auth (qop = #{sparams['qop'].join(',')})" unless sparams['qop'].include?("auth")
-
-          response = {
-            :nonce => sparams['nonce'],
-            :username => @user,
-            :realm => sparams['realm'],
-            :cnonce => Digest::MD5.hexdigest("%.15f:%.15f:%d" % [Time.now.to_f, rand, Process.pid.to_s]),
-            :'digest-uri' => 'imap/' + sparams['realm'],
-            :qop => 'auth',
-            :maxbuf => 65535,
-            :nc => "%08d" % nc(sparams['nonce']),
-            :charset => sparams['charset'],
-          }
-
-          response[:authzid] = @authname unless @authname.nil?
-
-          # now, the real thing
-          a0 = Digest::MD5.digest( [ response.values_at(:username, :realm), @password ].join(':') )
-
-          a1 = [ a0, response.values_at(:nonce,:cnonce) ].join(':')
-          a1 << ':' + response[:authzid] unless response[:authzid].nil?
-
-          a2 = "AUTHENTICATE:" + response[:'digest-uri']
-          a2 << ":00000000000000000000000000000000" if response[:qop] and response[:qop] =~ /^auth-(?:conf|int)$/
-
-          response[:response] = Digest::MD5.hexdigest(
-            [
-             Digest::MD5.hexdigest(a1),
-             response.values_at(:nonce, :nc, :cnonce, :qop),
-             Digest::MD5.hexdigest(a2)
-            ].join(':')
-          )
-
-          return response.keys.map {|key| qdval(key.to_s, response[key]) }.join(',')
-        when STAGE_TWO
-          @stage = nil
-          # if at the second stage, return an empty string
-          if challenge =~ /rspauth=/
-            return ''
-          else
-            raise ResponseParseError, challenge
-          end
-        else
-          raise ResponseParseError, challenge
-        end
-      end
-
-      def initialize(user, password, authname = nil)
-        @user, @password, @authname = user, password, authname
-        @nc, @stage = {}, STAGE_ONE
-      end
-
-      private
-
-      STAGE_ONE = :stage_one
-      STAGE_TWO = :stage_two
-
-      def nc(nonce)
-        if @nc.has_key? nonce
-          @nc[nonce] = @nc[nonce] + 1
-        else
-          @nc[nonce] = 1
-        end
-        return @nc[nonce]
-      end
-
-      # some responses need quoting
-      def qdval(k, v)
-        return if k.nil? or v.nil?
-        if %w"username authzid realm nonce cnonce digest-uri qop".include? k
-          v.gsub!(/([\\"])/, "\\\1")
-          return '%s="%s"' % [k, v]
-        else
-          return '%s=%s' % [k, v]
-        end
-      end
-    end
-    add_authenticator "DIGEST-MD5", DigestMD5Authenticator
-
-    # Superclass of IMAP errors.
-    class Error < StandardError
-    end
-
-    # Error raised when data is in the incorrect format.
-    class DataFormatError < Error
-    end
-
-    # Error raised when a response from the server is non-parseable.
-    class ResponseParseError < Error
-    end
-
-    # Superclass of all errors used to encapsulate "fail" responses
-    # from the server.
-    class ResponseError < Error
-
-      # The response that caused this error
-      attr_accessor :response
-
-      def initialize(response)
-        @response = response
-
-        super @response.data.text
-      end
-
-    end
-
-    # Error raised upon a "NO" response from the server, indicating
-    # that the client command could not be completed successfully.
-    class NoResponseError < ResponseError
-    end
-
-    # Error raised upon a "BAD" response from the server, indicating
-    # that the client command violated the IMAP protocol, or an internal
-    # server failure has occurred.
-    class BadResponseError < ResponseError
-    end
-
-    # Error raised upon a "BYE" response from the server, indicating
-    # that the client is not being allowed to login, or has been timed
-    # out due to inactivity.
-    class ByeResponseError < ResponseError
-    end
-
-    # Error raised when too many flags are interned to symbols.
-    class FlagCountError < Error
-    end
-  end
-end
-
-if __FILE__ == $0
-  # :enddoc:
-  require "getoptlong"
-
-  $stdout.sync = true
-  $port = nil
-  $user = ENV["USER"] || ENV["LOGNAME"]
-  $auth = "login"
-  $ssl = false
-  $starttls = false
-
-  def usage
-    <<EOF
-usage: #{$0} [options] <host>
-
-  --help                        print this message
-  --port=PORT                   specifies port
-  --user=USER                   specifies user
-  --auth=AUTH                   specifies auth type
-  --starttls                    use starttls
-  --ssl                         use ssl
-EOF
-  end
-
-  begin
-    require 'io/console'
-  rescue LoadError
-    def _noecho(&block)
-      system("stty", "-echo")
-      begin
-        yield STDIN
-      ensure
-        system("stty", "echo")
-      end
-    end
-  else
-    def _noecho(&block)
-      STDIN.noecho(&block)
-    end
-  end
-
-  def get_password
-    print "password: "
-    begin
-      return _noecho(&:gets).chomp
-    ensure
-      puts
-    end
-  end
-
-  def get_command
-    printf("%s@%s> ", $user, $host)
-    if line = gets
-      return line.strip.split(/\s+/)
-    else
-      return nil
-    end
-  end
-
-  parser = GetoptLong.new
-  parser.set_options(['--debug', GetoptLong::NO_ARGUMENT],
-                     ['--help', GetoptLong::NO_ARGUMENT],
-                     ['--port', GetoptLong::REQUIRED_ARGUMENT],
-                     ['--user', GetoptLong::REQUIRED_ARGUMENT],
-                     ['--auth', GetoptLong::REQUIRED_ARGUMENT],
-                     ['--starttls', GetoptLong::NO_ARGUMENT],
-                     ['--ssl', GetoptLong::NO_ARGUMENT])
-  begin
-    parser.each_option do |name, arg|
-      case name
-      when "--port"
-        $port = arg
-      when "--user"
-        $user = arg
-      when "--auth"
-        $auth = arg
-      when "--ssl"
-        $ssl = true
-      when "--starttls"
-        $starttls = true
-      when "--debug"
-        Net::IMAP.debug = true
-      when "--help"
-        usage
-        exit
-      end
-    end
-  rescue
-    abort usage
-  end
-
-  $host = ARGV.shift
-  unless $host
-    abort usage
-  end
-
-  imap = Net::IMAP.new($host, :port => $port, :ssl => $ssl)
-  begin
-    imap.starttls if $starttls
-    class << password = method(:get_password)
-      alias to_str call
-    end
-    imap.authenticate($auth, $user, password)
-    while true
-      cmd, *args = get_command
-      break unless cmd
-      begin
-        case cmd
-        when "list"
-          for mbox in imap.list("", args[0] || "*")
-            if mbox.attr.include?(Net::IMAP::NOSELECT)
-              prefix = "!"
-            elsif mbox.attr.include?(Net::IMAP::MARKED)
-              prefix = "*"
-            else
-              prefix = " "
-            end
-            print prefix, mbox.name, "\n"
-          end
-        when "select"
-          imap.select(args[0] || "inbox")
-          print "ok\n"
-        when "close"
-          imap.close
-          print "ok\n"
-        when "summary"
-          unless messages = imap.responses["EXISTS"][-1]
-            puts "not selected"
-            next
-          end
-          if messages > 0
-            for data in imap.fetch(1..-1, ["ENVELOPE"])
-              print data.seqno, ": ", data.attr["ENVELOPE"].subject, "\n"
-            end
-          else
-            puts "no message"
-          end
-        when "fetch"
-          if args[0]
-            data = imap.fetch(args[0].to_i, ["RFC822.HEADER", "RFC822.TEXT"])[0]
-            puts data.attr["RFC822.HEADER"]
-            puts data.attr["RFC822.TEXT"]
-          else
-            puts "missing argument"
-          end
-        when "logout", "exit", "quit"
-          break
-        when "help", "?"
-          print <<EOF
-list [pattern]                  list mailboxes
-select [mailbox]                select mailbox
-close                           close mailbox
-summary                         display summary
-fetch [msgno]                   display message
-logout                          logout
-help, ?                         display help message
-EOF
-        else
-          print "unknown command: ", cmd, "\n"
-        end
-      rescue Net::IMAP::Error
-        puts $!
-      end
-    end
-  ensure
-    imap.logout
-    imap.disconnect
-  end
-end
-
diff --git a/lib/net/net-protocol.gemspec b/lib/net/net-protocol.gemspec
new file mode 100644
index 0000000000..2d911a966c
--- /dev/null
+++ b/lib/net/net-protocol.gemspec
@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+name = File.basename(__FILE__, ".gemspec")
+version = ["lib", Array.new(name.count("-"), "..").join("/")].find do |dir|
+  break File.foreach(File.join(__dir__, dir, "#{name.tr('-', '/')}.rb")) do |line|
+    /^\s*VERSION\s*=\s*"(.*)"/ =~ line and break $1
+  end rescue nil
+end
+
+Gem::Specification.new do |spec|
+  spec.name          = name
+  spec.version       = version
+  spec.authors = ["Yukihiro Matsumoto"]
+  spec.email = ["matz@ruby-lang.org"]
+
+  spec.summary       = %q{The abstract interface for net-* client.}
+  spec.description   = %q{The abstract interface for net-* client.}
+  spec.homepage      = "https://github.com/ruby/net-protocol"
+  spec.required_ruby_version = Gem::Requirement.new(">= 2.6.0")
+  spec.licenses      = ["Ruby", "BSD-2-Clause"]
+
+  spec.metadata["homepage_uri"] = spec.homepage
+  spec.metadata["source_code_uri"] = spec.homepage
+  spec.metadata["changelog_uri"] = spec.homepage + "/releases"
+
+  # Specify which files should be added to the gem when it is released.
+  # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
+  excludes = %W[/.git* /bin /test /*file /#{File.basename(__FILE__)}]
+  spec.files = IO.popen(%W[git -C #{__dir__} ls-files -z --] + excludes.map {|e| ":^#{e}"}, &:read).split("\x0")
+  spec.require_paths = ["lib"]
+
+  spec.add_dependency "timeout"
+end
diff --git a/lib/net/pop.rb b/lib/net/pop.rb
deleted file mode 100644
index ff2d77f72a..0000000000
--- a/lib/net/pop.rb
+++ /dev/null
@@ -1,1021 +0,0 @@
-# = net/pop.rb
-#
-# Copyright (c) 1999-2007 Yukihiro Matsumoto.
-#
-# Copyright (c) 1999-2007 Minero Aoki.
-#
-# Written & maintained by Minero Aoki <aamine@loveruby.net>.
-#
-# Documented by William Webber and Minero Aoki.
-#
-# This program is free software. You can re-distribute and/or
-# modify this program under the same terms as Ruby itself,
-# Ruby Distribute License.
-#
-# NOTE: You can find Japanese version of this document at:
-# http://www.ruby-lang.org/ja/man/html/net_pop.html
-#
-#   $Id$
-#
-# See Net::POP3 for documentation.
-#
-
-require 'net/protocol'
-require 'digest/md5'
-require 'timeout'
-
-begin
-  require "openssl"
-rescue LoadError
-end
-
-module Net
-
-  # Non-authentication POP3 protocol error
-  # (reply code "-ERR", except authentication).
-  class POPError < ProtocolError; end
-
-  # POP3 authentication error.
-  class POPAuthenticationError < ProtoAuthError; end
-
-  # Unexpected response from the server.
-  class POPBadResponse < POPError; end
-
-  #
-  # = Net::POP3
-  #
-  # == What is This Library?
-  #
-  # This library provides functionality for retrieving
-  # email via POP3, the Post Office Protocol version 3. For details
-  # of POP3, see [RFC1939] (http://www.ietf.org/rfc/rfc1939.txt).
-  #
-  # == Examples
-  #
-  # === Retrieving Messages
-  #
-  # This example retrieves messages from the server and deletes them
-  # on the server.
-  #
-  # Messages are written to files named 'inbox/1', 'inbox/2', ....
-  # Replace 'pop.example.com' with your POP3 server address, and
-  # 'YourAccount' and 'YourPassword' with the appropriate account
-  # details.
-  #
-  #     require 'net/pop'
-  #
-  #     pop = Net::POP3.new('pop.example.com')
-  #     pop.start('YourAccount', 'YourPassword')             # (1)
-  #     if pop.mails.empty?
-  #       puts 'No mail.'
-  #     else
-  #       i = 0
-  #       pop.each_mail do |m|   # or "pop.mails.each ..."   # (2)
-  #         File.open("inbox/#{i}", 'w') do |f|
-  #           f.write m.pop
-  #         end
-  #         m.delete
-  #         i += 1
-  #       end
-  #       puts "#{pop.mails.size} mails popped."
-  #     end
-  #     pop.finish                                           # (3)
-  #
-  # 1. Call Net::POP3#start and start POP session.
-  # 2. Access messages by using POP3#each_mail and/or POP3#mails.
-  # 3. Close POP session by calling POP3#finish or use the block form of #start.
-  #
-  # === Shortened Code
-  #
-  # The example above is very verbose. You can shorten the code by using
-  # some utility methods. First, the block form of Net::POP3.start can
-  # be used instead of POP3.new, POP3#start and POP3#finish.
-  #
-  #     require 'net/pop'
-  #
-  #     Net::POP3.start('pop.example.com', 110,
-  #                     'YourAccount', 'YourPassword') do |pop|
-  #       if pop.mails.empty?
-  #         puts 'No mail.'
-  #       else
-  #         i = 0
-  #         pop.each_mail do |m|   # or "pop.mails.each ..."
-  #           File.open("inbox/#{i}", 'w') do |f|
-  #             f.write m.pop
-  #           end
-  #           m.delete
-  #           i += 1
-  #         end
-  #         puts "#{pop.mails.size} mails popped."
-  #       end
-  #     end
-  #
-  # POP3#delete_all is an alternative for #each_mail and #delete.
-  #
-  #     require 'net/pop'
-  #
-  #     Net::POP3.start('pop.example.com', 110,
-  #                     'YourAccount', 'YourPassword') do |pop|
-  #       if pop.mails.empty?
-  #         puts 'No mail.'
-  #       else
-  #         i = 1
-  #         pop.delete_all do |m|
-  #           File.open("inbox/#{i}", 'w') do |f|
-  #             f.write m.pop
-  #           end
-  #           i += 1
-  #         end
-  #       end
-  #     end
-  #
-  # And here is an even shorter example.
-  #
-  #     require 'net/pop'
-  #
-  #     i = 0
-  #     Net::POP3.delete_all('pop.example.com', 110,
-  #                          'YourAccount', 'YourPassword') do |m|
-  #       File.open("inbox/#{i}", 'w') do |f|
-  #         f.write m.pop
-  #       end
-  #       i += 1
-  #     end
-  #
-  # === Memory Space Issues
-  #
-  # All the examples above get each message as one big string.
-  # This example avoids this.
-  #
-  #     require 'net/pop'
-  #
-  #     i = 1
-  #     Net::POP3.delete_all('pop.example.com', 110,
-  #                          'YourAccount', 'YourPassword') do |m|
-  #       File.open("inbox/#{i}", 'w') do |f|
-  #         m.pop do |chunk|    # get a message little by little.
-  #           f.write chunk
-  #         end
-  #         i += 1
-  #       end
-  #     end
-  #
-  # === Using APOP
-  #
-  # The net/pop library supports APOP authentication.
-  # To use APOP, use the Net::APOP class instead of the Net::POP3 class.
-  # You can use the utility method, Net::POP3.APOP(). For example:
-  #
-  #     require 'net/pop'
-  #
-  #     # Use APOP authentication if $isapop == true
-  #     pop = Net::POP3.APOP($is_apop).new('apop.example.com', 110)
-  #     pop.start(YourAccount', 'YourPassword') do |pop|
-  #       # Rest of the code is the same.
-  #     end
-  #
-  # === Fetch Only Selected Mail Using 'UIDL' POP Command
-  #
-  # If your POP server provides UIDL functionality,
-  # you can grab only selected mails from the POP server.
-  # e.g.
-  #
-  #     def need_pop?( id )
-  #       # determine if we need pop this mail...
-  #     end
-  #
-  #     Net::POP3.start('pop.example.com', 110,
-  #                     'Your account', 'Your password') do |pop|
-  #       pop.mails.select { |m| need_pop?(m.unique_id) }.each do |m|
-  #         do_something(m.pop)
-  #       end
-  #     end
-  #
-  # The POPMail#unique_id() method returns the unique-id of the message as a
-  # String. Normally the unique-id is a hash of the message.
-  #
-  class POP3 < Protocol
-
-    # svn revision of this library
-    Revision = %q$Revision$.split[1]
-
-    #
-    # Class Parameters
-    #
-
-    # returns the port for POP3
-    def POP3.default_port
-      default_pop3_port()
-    end
-
-    # The default port for POP3 connections, port 110
-    def POP3.default_pop3_port
-      110
-    end
-
-    # The default port for POP3S connections, port 995
-    def POP3.default_pop3s_port
-      995
-    end
-
-    def POP3.socket_type   #:nodoc: obsolete
-      Net::InternetMessageIO
-    end
-
-    #
-    # Utilities
-    #
-
-    # Returns the APOP class if +isapop+ is true; otherwise, returns
-    # the POP class.  For example:
-    #
-    #     # Example 1
-    #     pop = Net::POP3::APOP($is_apop).new(addr, port)
-    #
-    #     # Example 2
-    #     Net::POP3::APOP($is_apop).start(addr, port) do |pop|
-    #       ....
-    #     end
-    #
-    def POP3.APOP(isapop)
-      isapop ? APOP : POP3
-    end
-
-    # Starts a POP3 session and iterates over each POPMail object,
-    # yielding it to the +block+.
-    # This method is equivalent to:
-    #
-    #     Net::POP3.start(address, port, account, password) do |pop|
-    #       pop.each_mail do |m|
-    #         yield m
-    #       end
-    #     end
-    #
-    # This method raises a POPAuthenticationError if authentication fails.
-    #
-    # === Example
-    #
-    #     Net::POP3.foreach('pop.example.com', 110,
-    #                       'YourAccount', 'YourPassword') do |m|
-    #       file.write m.pop
-    #       m.delete if $DELETE
-    #     end
-    #
-    def POP3.foreach(address, port = nil,
-                     account = nil, password = nil,
-                     isapop = false, &block)  # :yields: message
-      start(address, port, account, password, isapop) {|pop|
-        pop.each_mail(&block)
-      }
-    end
-
-    # Starts a POP3 session and deletes all messages on the server.
-    # If a block is given, each POPMail object is yielded to it before
-    # being deleted.
-    #
-    # This method raises a POPAuthenticationError if authentication fails.
-    #
-    # === Example
-    #
-    #     Net::POP3.delete_all('pop.example.com', 110,
-    #                          'YourAccount', 'YourPassword') do |m|
-    #       file.write m.pop
-    #     end
-    #
-    def POP3.delete_all(address, port = nil,
-                        account = nil, password = nil,
-                        isapop = false, &block)
-      start(address, port, account, password, isapop) {|pop|
-        pop.delete_all(&block)
-      }
-    end
-
-    # Opens a POP3 session, attempts authentication, and quits.
-    #
-    # This method raises POPAuthenticationError if authentication fails.
-    #
-    # === Example: normal POP3
-    #
-    #     Net::POP3.auth_only('pop.example.com', 110,
-    #                         'YourAccount', 'YourPassword')
-    #
-    # === Example: APOP
-    #
-    #     Net::POP3.auth_only('pop.example.com', 110,
-    #                         'YourAccount', 'YourPassword', true)
-    #
-    def POP3.auth_only(address, port = nil,
-                       account = nil, password = nil,
-                       isapop = false)
-      new(address, port, isapop).auth_only account, password
-    end
-
-    # Starts a pop3 session, attempts authentication, and quits.
-    # This method must not be called while POP3 session is opened.
-    # This method raises POPAuthenticationError if authentication fails.
-    def auth_only(account, password)
-      raise IOError, 'opening previously opened POP session' if started?
-      start(account, password) {
-        ;
-      }
-    end
-
-    #
-    # SSL
-    #
-
-    @ssl_params = nil
-
-    # call-seq:
-    #    Net::POP.enable_ssl(params = {})
-    #
-    # Enable SSL for all new instances.
-    # +params+ is passed to OpenSSL::SSLContext#set_params.
-    def POP3.enable_ssl(*args)
-      @ssl_params = create_ssl_params(*args)
-    end
-
-    # Constructs proper parameters from arguments
-    def POP3.create_ssl_params(verify_or_params = {}, certs = nil)
-      begin
-        params = verify_or_params.to_hash
-      rescue NoMethodError
-        params = {}
-        params[:verify_mode] = verify_or_params
-        if certs
-          if File.file?(certs)
-            params[:ca_file] = certs
-          elsif File.directory?(certs)
-            params[:ca_path] = certs
-          end
-        end
-      end
-      return params
-    end
-
-    # Disable SSL for all new instances.
-    def POP3.disable_ssl
-      @ssl_params = nil
-    end
-
-    # returns the SSL Parameters
-    #
-    # see also POP3.enable_ssl
-    def POP3.ssl_params
-      return @ssl_params
-    end
-
-    # returns +true+ if POP3.ssl_params is set
-    def POP3.use_ssl?
-      return !@ssl_params.nil?
-    end
-
-    # returns whether verify_mode is enable from POP3.ssl_params
-    def POP3.verify
-      return @ssl_params[:verify_mode]
-    end
-
-    # returns the :ca_file or :ca_path from POP3.ssh_params
-    def POP3.certs
-      return @ssl_params[:ca_file] || @ssl_params[:ca_path]
-    end
-
-    #
-    # Session management
-    #
-
-    # Creates a new POP3 object and open the connection.  Equivalent to
-    #
-    #   Net::POP3.new(address, port, isapop).start(account, password)
-    #
-    # If +block+ is provided, yields the newly-opened POP3 object to it,
-    # and automatically closes it at the end of the session.
-    #
-    # === Example
-    #
-    #    Net::POP3.start(addr, port, account, password) do |pop|
-    #      pop.each_mail do |m|
-    #        file.write m.pop
-    #        m.delete
-    #      end
-    #    end
-    #
-    def POP3.start(address, port = nil,
-                   account = nil, password = nil,
-                   isapop = false, &block)   # :yield: pop
-      new(address, port, isapop).start(account, password, &block)
-    end
-
-    # Creates a new POP3 object.
-    #
-    # +address+ is the hostname or ip address of your POP3 server.
-    #
-    # The optional +port+ is the port to connect to.
-    #
-    # The optional +isapop+ specifies whether this connection is going
-    # to use APOP authentication; it defaults to +false+.
-    #
-    # This method does *not* open the TCP connection.
-    def initialize(addr, port = nil, isapop = false)
-      @address = addr
-      @ssl_params = POP3.ssl_params
-      @port = port
-      @apop = isapop
-
-      @command = nil
-      @socket = nil
-      @started = false
-      @open_timeout = 30
-      @read_timeout = 60
-      @debug_output = nil
-
-      @mails = nil
-      @n_mails = nil
-      @n_bytes = nil
-    end
-
-    # Does this instance use APOP authentication?
-    def apop?
-      @apop
-    end
-
-    # does this instance use SSL?
-    def use_ssl?
-      return !@ssl_params.nil?
-    end
-
-    # call-seq:
-    #    Net::POP#enable_ssl(params = {})
-    #
-    # Enables SSL for this instance.  Must be called before the connection is
-    # established to have any effect.
-    # +params[:port]+ is port to establish the SSL connection on; Defaults to 995.
-    # +params+ (except :port) is passed to OpenSSL::SSLContext#set_params.
-    def enable_ssl(verify_or_params = {}, certs = nil, port = nil)
-      begin
-        @ssl_params = verify_or_params.to_hash.dup
-        @port = @ssl_params.delete(:port) || @port
-      rescue NoMethodError
-        @ssl_params = POP3.create_ssl_params(verify_or_params, certs)
-        @port = port || @port
-      end
-    end
-
-    # Disable SSL for all new instances.
-    def disable_ssl
-      @ssl_params = nil
-    end
-
-    # Provide human-readable stringification of class state.
-    def inspect
-      "#<#{self.class} #{@address}:#{@port} open=#{@started}>"
-    end
-
-    # *WARNING*: This method causes a serious security hole.
-    # Use this method only for debugging.
-    #
-    # Set an output stream for debugging.
-    #
-    # === Example
-    #
-    #   pop = Net::POP.new(addr, port)
-    #   pop.set_debug_output $stderr
-    #   pop.start(account, passwd) do |pop|
-    #     ....
-    #   end
-    #
-    def set_debug_output(arg)
-      @debug_output = arg
-    end
-
-    # The address to connect to.
-    attr_reader :address
-
-    # The port number to connect to.
-    def port
-      return @port || (use_ssl? ? POP3.default_pop3s_port : POP3.default_pop3_port)
-    end
-
-    # Seconds to wait until a connection is opened.
-    # If the POP3 object cannot open a connection within this time,
-    # it raises a TimeoutError exception. The default value is 30 seconds.
-    attr_accessor :open_timeout
-
-    # Seconds to wait until reading one block (by one read(1) call).
-    # If the POP3 object cannot complete a read() within this time,
-    # it raises a TimeoutError exception. The default value is 60 seconds.
-    attr_reader :read_timeout
-
-    # Set the read timeout.
-    def read_timeout=(sec)
-      @command.socket.read_timeout = sec if @command
-      @read_timeout = sec
-    end
-
-    # +true+ if the POP3 session has started.
-    def started?
-      @started
-    end
-
-    alias active? started?   #:nodoc: obsolete
-
-    # Starts a POP3 session.
-    #
-    # When called with block, gives a POP3 object to the block and
-    # closes the session after block call finishes.
-    #
-    # This method raises a POPAuthenticationError if authentication fails.
-    def start(account, password) # :yield: pop
-      raise IOError, 'POP session already started' if @started
-      if block_given?
-        begin
-          do_start account, password
-          return yield(self)
-        ensure
-          do_finish
-        end
-      else
-        do_start account, password
-        return self
-      end
-    end
-
-    # internal method for Net::POP3.start
-    def do_start(account, password) # :nodoc:
-      s = timeout(@open_timeout) { TCPSocket.open(@address, port) }
-      if use_ssl?
-        raise 'openssl library not installed' unless defined?(OpenSSL)
-        context = OpenSSL::SSL::SSLContext.new
-        context.set_params(@ssl_params)
-        s = OpenSSL::SSL::SSLSocket.new(s, context)
-        s.sync_close = true
-        s.connect
-        if context.verify_mode != OpenSSL::SSL::VERIFY_NONE
-          s.post_connection_check(@address)
-        end
-      end
-      @socket = InternetMessageIO.new(s)
-      logging "POP session started: #{@address}:#{@port} (#{@apop ? 'APOP' : 'POP'})"
-      @socket.read_timeout = @read_timeout
-      @socket.debug_output = @debug_output
-      on_connect
-      @command = POP3Command.new(@socket)
-      if apop?
-        @command.apop account, password
-      else
-        @command.auth account, password
-      end
-      @started = true
-    ensure
-      # Authentication failed, clean up connection.
-      unless @started
-        s.close if s and not s.closed?
-        @socket = nil
-        @command = nil
-      end
-    end
-    private :do_start
-
-    # Does nothing
-    def on_connect # :nodoc:
-    end
-    private :on_connect
-
-    # Finishes a POP3 session and closes TCP connection.
-    def finish
-      raise IOError, 'POP session not yet started' unless started?
-      do_finish
-    end
-
-    # nil's out the:
-    # - mails
-    # - number counter for mails
-    # - number counter for bytes
-    # - quits the current command, if any
-    def do_finish # :nodoc:
-      @mails = nil
-      @n_mails = nil
-      @n_bytes = nil
-      @command.quit if @command
-    ensure
-      @started = false
-      @command = nil
-      @socket.close if @socket and not @socket.closed?
-      @socket = nil
-    end
-    private :do_finish
-
-    # Returns the current command.
-    #
-    # Raises IOError if there is no active socket
-    def command # :nodoc:
-      raise IOError, 'POP session not opened yet' \
-                                      if not @socket or @socket.closed?
-      @command
-    end
-    private :command
-
-    #
-    # POP protocol wrapper
-    #
-
-    # Returns the number of messages on the POP server.
-    def n_mails
-      return @n_mails if @n_mails
-      @n_mails, @n_bytes = command().stat
-      @n_mails
-    end
-
-    # Returns the total size in bytes of all the messages on the POP server.
-    def n_bytes
-      return @n_bytes if @n_bytes
-      @n_mails, @n_bytes = command().stat
-      @n_bytes
-    end
-
-    # Returns an array of Net::POPMail objects, representing all the
-    # messages on the server.  This array is renewed when the session
-    # restarts; otherwise, it is fetched from the server the first time
-    # this method is called (directly or indirectly) and cached.
-    #
-    # This method raises a POPError if an error occurs.
-    def mails
-      return @mails.dup if @mails
-      if n_mails() == 0
-        # some popd raises error for LIST on the empty mailbox.
-        @mails = []
-        return []
-      end
-
-      @mails = command().list.map {|num, size|
-        POPMail.new(num, size, self, command())
-      }
-      @mails.dup
-    end
-
-    # Yields each message to the passed-in block in turn.
-    # Equivalent to:
-    #
-    #   pop3.mails.each do |popmail|
-    #     ....
-    #   end
-    #
-    # This method raises a POPError if an error occurs.
-    def each_mail(&block)  # :yield: message
-      mails().each(&block)
-    end
-
-    alias each each_mail
-
-    # Deletes all messages on the server.
-    #
-    # If called with a block, yields each message in turn before deleting it.
-    #
-    # === Example
-    #
-    #     n = 1
-    #     pop.delete_all do |m|
-    #       File.open("inbox/#{n}") do |f|
-    #         f.write m.pop
-    #       end
-    #       n += 1
-    #     end
-    #
-    # This method raises a POPError if an error occurs.
-    #
-    def delete_all # :yield: message
-      mails().each do |m|
-        yield m if block_given?
-        m.delete unless m.deleted?
-      end
-    end
-
-    # Resets the session.  This clears all "deleted" marks from messages.
-    #
-    # This method raises a POPError if an error occurs.
-    def reset
-      command().rset
-      mails().each do |m|
-        m.instance_eval {
-          @deleted = false
-        }
-      end
-    end
-
-    def set_all_uids   #:nodoc: internal use only (called from POPMail#uidl)
-      uidl = command().uidl
-      @mails.each {|m| m.uid = uidl[m.number] }
-    end
-
-    # deguging output for +msg+
-    def logging(msg)
-      @debug_output << msg + "\n" if @debug_output
-    end
-
-  end   # class POP3
-
-  # class aliases
-  POP = POP3
-  POPSession  = POP3
-  POP3Session = POP3
-
-  #
-  # This class is equivalent to POP3, except that it uses APOP authentication.
-  #
-  class APOP < POP3
-    # Always returns true.
-    def apop?
-      true
-    end
-  end
-
-  # class aliases
-  APOPSession = APOP
-
-  #
-  # This class represents a message which exists on the POP server.
-  # Instances of this class are created by the POP3 class; they should
-  # not be directly created by the user.
-  #
-  class POPMail
-
-    def initialize(num, len, pop, cmd)   #:nodoc:
-      @number = num
-      @length = len
-      @pop = pop
-      @command = cmd
-      @deleted = false
-      @uid = nil
-    end
-
-    # The sequence number of the message on the server.
-    attr_reader :number
-
-    # The length of the message in octets.
-    attr_reader :length
-    alias size length
-
-    # Provide human-readable stringification of class state.
-    def inspect
-      "#<#{self.class} #{@number}#{@deleted ? ' deleted' : ''}>"
-    end
-
-    #
-    # This method fetches the message.  If called with a block, the
-    # message is yielded to the block one chunk at a time.  If called
-    # without a block, the message is returned as a String.  The optional
-    # +dest+ argument will be prepended to the returned String; this
-    # argument is essentially obsolete.
-    #
-    # === Example without block
-    #
-    #     POP3.start('pop.example.com', 110,
-    #                'YourAccount, 'YourPassword') do |pop|
-    #       n = 1
-    #       pop.mails.each do |popmail|
-    #         File.open("inbox/#{n}", 'w') do |f|
-    #           f.write popmail.pop
-    #         end
-    #         popmail.delete
-    #         n += 1
-    #       end
-    #     end
-    #
-    # === Example with block
-    #
-    #     POP3.start('pop.example.com', 110,
-    #                'YourAccount, 'YourPassword') do |pop|
-    #       n = 1
-    #       pop.mails.each do |popmail|
-    #         File.open("inbox/#{n}", 'w') do |f|
-    #           popmail.pop do |chunk|            ####
-    #             f.write chunk
-    #           end
-    #         end
-    #         n += 1
-    #       end
-    #     end
-    #
-    # This method raises a POPError if an error occurs.
-    #
-    def pop( dest = '', &block ) # :yield: message_chunk
-      if block_given?
-        @command.retr(@number, &block)
-        nil
-      else
-        @command.retr(@number) do |chunk|
-          dest << chunk
-        end
-        dest
-      end
-    end
-
-    alias all pop    #:nodoc: obsolete
-    alias mail pop   #:nodoc: obsolete
-
-    # Fetches the message header and +lines+ lines of body.
-    #
-    # The optional +dest+ argument is obsolete.
-    #
-    # This method raises a POPError if an error occurs.
-    def top(lines, dest = '')
-      @command.top(@number, lines) do |chunk|
-        dest << chunk
-      end
-      dest
-    end
-
-    # Fetches the message header.
-    #
-    # The optional +dest+ argument is obsolete.
-    #
-    # This method raises a POPError if an error occurs.
-    def header(dest = '')
-      top(0, dest)
-    end
-
-    # Marks a message for deletion on the server.  Deletion does not
-    # actually occur until the end of the session; deletion may be
-    # cancelled for _all_ marked messages by calling POP3#reset().
-    #
-    # This method raises a POPError if an error occurs.
-    #
-    # === Example
-    #
-    #     POP3.start('pop.example.com', 110,
-    #                'YourAccount, 'YourPassword') do |pop|
-    #       n = 1
-    #       pop.mails.each do |popmail|
-    #         File.open("inbox/#{n}", 'w') do |f|
-    #           f.write popmail.pop
-    #         end
-    #         popmail.delete         ####
-    #         n += 1
-    #       end
-    #     end
-    #
-    def delete
-      @command.dele @number
-      @deleted = true
-    end
-
-    alias delete! delete    #:nodoc: obsolete
-
-    # True if the mail has been deleted.
-    def deleted?
-      @deleted
-    end
-
-    # Returns the unique-id of the message.
-    # Normally the unique-id is a hash string of the message.
-    #
-    # This method raises a POPError if an error occurs.
-    def unique_id
-      return @uid if @uid
-      @pop.set_all_uids
-      @uid
-    end
-
-    alias uidl unique_id
-
-    def uid=(uid)   #:nodoc: internal use only
-      @uid = uid
-    end
-
-  end   # class POPMail
-
-
-  class POP3Command   #:nodoc: internal use only
-
-    def initialize(sock)
-      @socket = sock
-      @error_occured = false
-      res = check_response(critical { recv_response() })
-      @apop_stamp = res.slice(/<[!-~]+@[!-~]+>/)
-    end
-
-    attr_reader :socket
-
-    def inspect
-      "#<#{self.class} socket=#{@socket}>"
-    end
-
-    def auth(account, password)
-      check_response_auth(critical {
-        check_response_auth(get_response('USER %s', account))
-        get_response('PASS %s', password)
-      })
-    end
-
-    def apop(account, password)
-      raise POPAuthenticationError, 'not APOP server; cannot login' \
-                                                      unless @apop_stamp
-      check_response_auth(critical {
-        get_response('APOP %s %s',
-                     account,
-                     Digest::MD5.hexdigest(@apop_stamp + password))
-      })
-    end
-
-    def list
-      critical {
-        getok 'LIST'
-        list = []
-        @socket.each_list_item do |line|
-          m = /\A(\d+)[ \t]+(\d+)/.match(line) or
-                  raise POPBadResponse, "bad response: #{line}"
-          list.push  [m[1].to_i, m[2].to_i]
-        end
-        return list
-      }
-    end
-
-    def stat
-      res = check_response(critical { get_response('STAT') })
-      m = /\A\+OK\s+(\d+)\s+(\d+)/.match(res) or
-              raise POPBadResponse, "wrong response format: #{res}"
-      [m[1].to_i, m[2].to_i]
-    end
-
-    def rset
-      check_response(critical { get_response('RSET') })
-    end
-
-    def top(num, lines = 0, &block)
-      critical {
-        getok('TOP %d %d', num, lines)
-        @socket.each_message_chunk(&block)
-      }
-    end
-
-    def retr(num, &block)
-      critical {
-        getok('RETR %d', num)
-        @socket.each_message_chunk(&block)
-      }
-    end
-
-    def dele(num)
-      check_response(critical { get_response('DELE %d', num) })
-    end
-
-    def uidl(num = nil)
-      if num
-        res = check_response(critical { get_response('UIDL %d', num) })
-        return res.split(/ /)[1]
-      else
-        critical {
-          getok('UIDL')
-          table = {}
-          @socket.each_list_item do |line|
-            num, uid = line.split
-            table[num.to_i] = uid
-          end
-          return table
-        }
-      end
-    end
-
-    def quit
-      check_response(critical { get_response('QUIT') })
-    end
-
-    private
-
-    def getok(fmt, *fargs)
-      @socket.writeline sprintf(fmt, *fargs)
-      check_response(recv_response())
-    end
-
-    def get_response(fmt, *fargs)
-      @socket.writeline sprintf(fmt, *fargs)
-      recv_response()
-    end
-
-    def recv_response
-      @socket.readline
-    end
-
-    def check_response(res)
-      raise POPError, res unless /\A\+OK/i =~ res
-      res
-    end
-
-    def check_response_auth(res)
-      raise POPAuthenticationError, res unless /\A\+OK/i =~ res
-      res
-    end
-
-    def critical
-      return '+OK dummy ok response' if @error_occured
-      begin
-        return yield()
-      rescue Exception
-        @error_occured = true
-        raise
-      end
-    end
-
-  end   # class POP3Command
-
-end   # module Net
diff --git a/lib/net/protocol.rb b/lib/net/protocol.rb
index f3744661f5..8c81298c0e 100644
--- a/lib/net/protocol.rb
+++ b/lib/net/protocol.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 #
 # = net/protocol.rb
 #
@@ -20,10 +21,13 @@
 
 require 'socket'
 require 'timeout'
+require 'io/wait'
 
 module Net # :nodoc:
 
   class Protocol   #:nodoc: internal use only
+    VERSION = "0.2.2"
+
     private
     def Protocol.protocol_param(name, val)
       module_eval(<<-End, __FILE__, __LINE__ + 1)
@@ -32,9 +36,38 @@ module Net # :nodoc:
         end
       End
     end
+
+    def ssl_socket_connect(s, timeout)
+      if timeout
+        while true
+          raise Net::OpenTimeout if timeout <= 0
+          start = Process.clock_gettime Process::CLOCK_MONOTONIC
+          # to_io is required because SSLSocket doesn't have wait_readable yet
+          case s.connect_nonblock(exception: false)
+          when :wait_readable; s.to_io.wait_readable(timeout)
+          when :wait_writable; s.to_io.wait_writable(timeout)
+          else; break
+          end
+          timeout -= Process.clock_gettime(Process::CLOCK_MONOTONIC) - start
+        end
+      else
+        s.connect
+      end
+    end
+
+    tcp_socket_parameters = TCPSocket.instance_method(:initialize).parameters
+    TCP_SOCKET_NEW_HAS_OPEN_TIMEOUT = if tcp_socket_parameters != [[:rest]]
+      tcp_socket_parameters.include?([:key, :open_timeout])
+    else
+      # Use Socket.tcp to find out since there is no parameters information for TCPSocket#initialize
+      # See discussion in https://github.com/ruby/net-http/pull/224
+      Socket.method(:tcp).parameters.include?([:key, :open_timeout])
+    end
+    private_constant :TCP_SOCKET_NEW_HAS_OPEN_TIMEOUT
   end
 
 
+  # :stopdoc:
   class ProtocolError          < StandardError; end
   class ProtoSyntaxError       < ProtocolError; end
   class ProtoFatalError        < ProtocolError; end
@@ -44,19 +77,70 @@ module Net # :nodoc:
   class ProtoCommandError      < ProtocolError; end
   class ProtoRetriableError    < ProtocolError; end
   ProtocRetryError = ProtoRetriableError
+  # :startdoc:
+
+  ##
+  # OpenTimeout, a subclass of Timeout::Error, is raised if a connection cannot
+  # be created within the open_timeout.
+
+  class OpenTimeout            < Timeout::Error; end
+
+  ##
+  # ReadTimeout, a subclass of Timeout::Error, is raised if a chunk of the
+  # response cannot be read within the read_timeout.
+
+  class ReadTimeout < Timeout::Error
+    # :stopdoc:
+    def initialize(io = nil)
+      @io = io
+    end
+    attr_reader :io
+
+    def message
+      msg = super
+      if @io
+        msg = "#{msg} with #{@io.inspect}"
+      end
+      msg
+    end
+  end
+
+  ##
+  # WriteTimeout, a subclass of Timeout::Error, is raised if a chunk of the
+  # response cannot be written within the write_timeout.  Not raised on Windows.
+
+  class WriteTimeout < Timeout::Error
+    # :stopdoc:
+    def initialize(io = nil)
+      @io = io
+    end
+    attr_reader :io
+
+    def message
+      msg = super
+      if @io
+        msg = "#{msg} with #{@io.inspect}"
+      end
+      msg
+    end
+  end
 
 
   class BufferedIO   #:nodoc: internal use only
-    def initialize(io)
+    def initialize(io, read_timeout: 60, write_timeout: 60, continue_timeout: nil, debug_output: nil)
       @io = io
-      @read_timeout = 60
-      @continue_timeout = nil
-      @debug_output = nil
-      @rbuf = ''
+      @read_timeout = read_timeout
+      @write_timeout = write_timeout
+      @continue_timeout = continue_timeout
+      @debug_output = debug_output
+      @rbuf = ''.b
+      @rbuf_empty = true
+      @rbuf_offset = 0
     end
 
     attr_reader :io
     attr_accessor :read_timeout
+    attr_accessor :write_timeout
     attr_accessor :continue_timeout
     attr_accessor :debug_output
 
@@ -82,17 +166,20 @@ module Net # :nodoc:
 
     public
 
-    def read(len, dest = '', ignore_eof = false)
+    def read(len, dest = ''.b, ignore_eof = false)
       LOG "reading #{len} bytes..."
       read_bytes = 0
       begin
-        while read_bytes + @rbuf.size < len
-          dest << (s = rbuf_consume(@rbuf.size))
-          read_bytes += s.size
+        while read_bytes + rbuf_size < len
+          if s = rbuf_consume_all
+            read_bytes += s.bytesize
+            dest << s
+          end
           rbuf_fill
         end
-        dest << (s = rbuf_consume(len - read_bytes))
-        read_bytes += s.size
+        s = rbuf_consume(len - read_bytes)
+        read_bytes += s.bytesize
+        dest << s
       rescue EOFError
         raise unless ignore_eof
       end
@@ -100,13 +187,15 @@ module Net # :nodoc:
       dest
     end
 
-    def read_all(dest = '')
+    def read_all(dest = ''.b)
       LOG 'reading all...'
       read_bytes = 0
       begin
         while true
-          dest << (s = rbuf_consume(@rbuf.size))
-          read_bytes += s.size
+          if s = rbuf_consume_all
+            read_bytes += s.bytesize
+            dest << s
+          end
           rbuf_fill
         end
       rescue EOFError
@@ -117,14 +206,16 @@ module Net # :nodoc:
     end
 
     def readuntil(terminator, ignore_eof = false)
+      offset = @rbuf_offset
       begin
-        until idx = @rbuf.index(terminator)
+        until idx = @rbuf.index(terminator, offset)
+          offset = @rbuf.bytesize
           rbuf_fill
         end
-        return rbuf_consume(idx + terminator.size)
+        return rbuf_consume(idx + terminator.bytesize - @rbuf_offset)
       rescue EOFError
         raise unless ignore_eof
-        return rbuf_consume(@rbuf.size)
+        return rbuf_consume
       end
     end
 
@@ -137,27 +228,64 @@ module Net # :nodoc:
     BUFSIZE = 1024 * 16
 
     def rbuf_fill
-      begin
-        @rbuf << @io.read_nonblock(BUFSIZE)
-      rescue IO::WaitReadable
-        if IO.select([@io], nil, nil, @read_timeout)
-          retry
+      tmp = @rbuf_empty ? @rbuf : nil
+      case rv = @io.read_nonblock(BUFSIZE, tmp, exception: false)
+      when String
+        @rbuf_empty = false
+        if rv.equal?(tmp)
+          @rbuf_offset = 0
         else
-          raise Timeout::Error
+          @rbuf << rv
+          rv.clear
         end
-      rescue IO::WaitWritable
+        return
+      when :wait_readable
+        (io = @io.to_io).wait_readable(@read_timeout) or raise Net::ReadTimeout.new(io)
+        # continue looping
+      when :wait_writable
         # OpenSSL::Buffering#read_nonblock may fail with IO::WaitWritable.
         # http://www.openssl.org/support/faq.html#PROG10
-        if IO.select(nil, [@io], nil, @read_timeout)
-          retry
-        else
-          raise Timeout::Error
-        end
+        (io = @io.to_io).wait_writable(@read_timeout) or raise Net::ReadTimeout.new(io)
+        # continue looping
+      when nil
+        raise EOFError, 'end of file reached'
+      end while true
+    end
+
+    def rbuf_flush
+      if @rbuf_empty
+        @rbuf.clear
+        @rbuf_offset = 0
       end
+      nil
     end
 
-    def rbuf_consume(len)
-      s = @rbuf.slice!(0, len)
+    def rbuf_size
+      @rbuf.bytesize - @rbuf_offset
+    end
+
+    def rbuf_consume_all
+      rbuf_consume if rbuf_size > 0
+    end
+
+    def rbuf_consume(len = nil)
+      if @rbuf_offset == 0 && (len.nil? || len == @rbuf.bytesize)
+        s = @rbuf
+        @rbuf = ''.b
+        @rbuf_offset = 0
+        @rbuf_empty = true
+      elsif len.nil?
+        s = @rbuf.byteslice(@rbuf_offset..-1)
+        @rbuf = ''.b
+        @rbuf_offset = 0
+        @rbuf_empty = true
+      else
+        s = @rbuf.byteslice(@rbuf_offset, len)
+        @rbuf_offset += len
+        @rbuf_empty = @rbuf_offset == @rbuf.bytesize
+        rbuf_flush
+      end
+
       @debug_output << %Q[-> #{s.dump}\n] if @debug_output
       s
     end
@@ -168,9 +296,9 @@ module Net # :nodoc:
 
     public
 
-    def write(str)
+    def write(*strs)
       writing {
-        write0 str
+        write0(*strs)
       }
     end
 
@@ -194,11 +322,34 @@ module Net # :nodoc:
       bytes
     end
 
-    def write0(str)
-      @debug_output << str.dump if @debug_output
-      len = @io.write(str)
-      @written_bytes += len
-      len
+    def write0(*strs)
+      @debug_output << strs.map(&:dump).join if @debug_output
+      orig_written_bytes = @written_bytes
+      strs.each_with_index do |str, i|
+        need_retry = true
+        case len = @io.write_nonblock(str, exception: false)
+        when Integer
+          @written_bytes += len
+          len -= str.bytesize
+          if len == 0
+            if strs.size == i+1
+              return @written_bytes - orig_written_bytes
+            else
+              need_retry = false
+              # next string
+            end
+          elsif len < 0
+            str = str.byteslice(len, -len)
+          else # len > 0
+            need_retry = false
+            # next string
+          end
+          # continue looping
+        when :wait_writable
+          (io = @io.to_io).wait_writable(@write_timeout) or raise Net::WriteTimeout.new(io)
+          # continue looping
+        end while need_retry
+      end
     end
 
     #
@@ -224,7 +375,7 @@ module Net # :nodoc:
 
 
   class InternetMessageIO < BufferedIO   #:nodoc: internal use only
-    def initialize(io)
+    def initialize(*, **)
       super
       @wbuf = nil
     end
@@ -239,7 +390,7 @@ module Net # :nodoc:
       read_bytes = 0
       while (line = readuntil("\r\n")) != ".\r\n"
         read_bytes += line.size
-        yield line.sub(/\A\./, '')
+        yield line.delete_prefix('.')
       end
       LOG_on()
       LOG "read message (#{read_bytes} bytes)"
@@ -255,7 +406,7 @@ module Net # :nodoc:
     def write_message_0(src)
       prev = @written_bytes
       each_crlf_line(src) do |line|
-        write0 line.sub(/\A\./, '..')
+        write0 dot_stuff(line)
       end
       @written_bytes - prev
     end
@@ -283,7 +434,7 @@ module Net # :nodoc:
       len = writing {
         using_each_crlf_line {
           begin
-            block.call(WriteAdapter.new(self, :write_message_0))
+            block.call(WriteAdapter.new(self.method(:write_message_0)))
           rescue LocalJumpError
             # allow `break' from writer block
           end
@@ -296,11 +447,15 @@ module Net # :nodoc:
 
     private
 
+    def dot_stuff(s)
+      s.sub(/\A\./, '..')
+    end
+
     def using_each_crlf_line
-      @wbuf = ''
+      @wbuf = ''.b
       yield
       if not @wbuf.empty?   # unterminated last line
-        write0 @wbuf.chomp + "\r\n"
+        write0 dot_stuff(@wbuf.chomp) + "\r\n"
       elsif @written_bytes == 0   # empty src
         write0 "\r\n"
       end
@@ -343,17 +498,17 @@ module Net # :nodoc:
   # The writer adapter class
   #
   class WriteAdapter
-    def initialize(socket, method)
-      @socket = socket
-      @method_id = method
+    # :stopdoc:
+    def initialize(writer)
+      @writer = writer
     end
 
     def inspect
-      "#<#{self.class} socket=#{@socket.inspect}>"
+      "#<#{self.class} writer=#{@writer.inspect}>"
     end
 
     def write(str)
-      @socket.__send__(@method_id, str)
+      @writer.call(str)
     end
 
     alias print write
diff --git a/lib/net/smtp.rb b/lib/net/smtp.rb
deleted file mode 100644
index ca6b70669b..0000000000
--- a/lib/net/smtp.rb
+++ /dev/null
@@ -1,1057 +0,0 @@
-# = net/smtp.rb
-#
-# Copyright (c) 1999-2007 Yukihiro Matsumoto.
-#
-# Copyright (c) 1999-2007 Minero Aoki.
-#
-# Written & maintained by Minero Aoki <aamine@loveruby.net>.
-#
-# Documented by William Webber and Minero Aoki.
-#
-# This program is free software. You can re-distribute and/or
-# modify this program under the same terms as Ruby itself.
-#
-# NOTE: You can find Japanese version of this document at:
-# http://www.ruby-lang.org/ja/man/html/net_smtp.html
-#
-# $Id$
-#
-# See Net::SMTP for documentation.
-#
-
-require 'net/protocol'
-require 'digest/md5'
-require 'timeout'
-begin
-  require 'openssl'
-rescue LoadError
-end
-
-module Net
-
-  # Module mixed in to all SMTP error classes
-  module SMTPError
-    # This *class* is a module for backward compatibility.
-    # In later release, this module becomes a class.
-  end
-
-  # Represents an SMTP authentication error.
-  class SMTPAuthenticationError < ProtoAuthError
-    include SMTPError
-  end
-
-  # Represents SMTP error code 420 or 450, a temporary error.
-  class SMTPServerBusy < ProtoServerError
-    include SMTPError
-  end
-
-  # Represents an SMTP command syntax error (error code 500)
-  class SMTPSyntaxError < ProtoSyntaxError
-    include SMTPError
-  end
-
-  # Represents a fatal SMTP error (error code 5xx, except for 500)
-  class SMTPFatalError < ProtoFatalError
-    include SMTPError
-  end
-
-  # Unexpected reply code returned from server.
-  class SMTPUnknownError < ProtoUnknownError
-    include SMTPError
-  end
-
-  # Command is not supported on server.
-  class SMTPUnsupportedCommand < ProtocolError
-    include SMTPError
-  end
-
-  #
-  # = Net::SMTP
-  #
-  # == What is This Library?
-  #
-  # This library provides functionality to send internet
-  # mail via SMTP, the Simple Mail Transfer Protocol. For details of
-  # SMTP itself, see [RFC2821] (http://www.ietf.org/rfc/rfc2821.txt).
-  #
-  # == What is This Library NOT?
-  #
-  # This library does NOT provide functions to compose internet mails.
-  # You must create them by yourself. If you want better mail support,
-  # try RubyMail or TMail. You can get both libraries from RAA.
-  # (http://www.ruby-lang.org/en/raa.html)
-  #
-  # FYI: the official documentation on internet mail is: [RFC2822] (http://www.ietf.org/rfc/rfc2822.txt).
-  #
-  # == Examples
-  #
-  # === Sending Messages
-  #
-  # You must open a connection to an SMTP server before sending messages.
-  # The first argument is the address of your SMTP server, and the second
-  # argument is the port number. Using SMTP.start with a block is the simplest
-  # way to do this. This way, the SMTP connection is closed automatically
-  # after the block is executed.
-  #
-  #     require 'net/smtp'
-  #     Net::SMTP.start('your.smtp.server', 25) do |smtp|
-  #       # Use the SMTP object smtp only in this block.
-  #     end
-  #
-  # Replace 'your.smtp.server' with your SMTP server. Normally
-  # your system manager or internet provider supplies a server
-  # for you.
-  #
-  # Then you can send messages.
-  #
-  #     msgstr = <<END_OF_MESSAGE
-  #     From: Your Name <your@mail.address>
-  #     To: Destination Address <someone@example.com>
-  #     Subject: test message
-  #     Date: Sat, 23 Jun 2001 16:26:43 +0900
-  #     Message-Id: <unique.message.id.string@example.com>
-  #
-  #     This is a test message.
-  #     END_OF_MESSAGE
-  #
-  #     require 'net/smtp'
-  #     Net::SMTP.start('your.smtp.server', 25) do |smtp|
-  #       smtp.send_message msgstr,
-  #                         'your@mail.address',
-  #                         'his_address@example.com'
-  #     end
-  #
-  # === Closing the Session
-  #
-  # You MUST close the SMTP session after sending messages, by calling
-  # the #finish method:
-  #
-  #     # using SMTP#finish
-  #     smtp = Net::SMTP.start('your.smtp.server', 25)
-  #     smtp.send_message msgstr, 'from@address', 'to@address'
-  #     smtp.finish
-  #
-  # You can also use the block form of SMTP.start/SMTP#start.  This closes
-  # the SMTP session automatically:
-  #
-  #     # using block form of SMTP.start
-  #     Net::SMTP.start('your.smtp.server', 25) do |smtp|
-  #       smtp.send_message msgstr, 'from@address', 'to@address'
-  #     end
-  #
-  # I strongly recommend this scheme.  This form is simpler and more robust.
-  #
-  # === HELO domain
-  #
-  # In almost all situations, you must provide a third argument
-  # to SMTP.start/SMTP#start. This is the domain name which you are on
-  # (the host to send mail from). It is called the "HELO domain".
-  # The SMTP server will judge whether it should send or reject
-  # the SMTP session by inspecting the HELO domain.
-  #
-  #     Net::SMTP.start('your.smtp.server', 25,
-  #                     'mail.from.domain') { |smtp| ... }
-  #
-  # === SMTP Authentication
-  #
-  # The Net::SMTP class supports three authentication schemes;
-  # PLAIN, LOGIN and CRAM MD5.  (SMTP Authentication: [RFC2554])
-  # To use SMTP authentication, pass extra arguments to
-  # SMTP.start/SMTP#start.
-  #
-  #     # PLAIN
-  #     Net::SMTP.start('your.smtp.server', 25, 'mail.from.domain',
-  #                     'Your Account', 'Your Password', :plain)
-  #     # LOGIN
-  #     Net::SMTP.start('your.smtp.server', 25, 'mail.from.domain',
-  #                     'Your Account', 'Your Password', :login)
-  #
-  #     # CRAM MD5
-  #     Net::SMTP.start('your.smtp.server', 25, 'mail.from.domain',
-  #                     'Your Account', 'Your Password', :cram_md5)
-  #
-  class SMTP
-
-    Revision = %q$Revision$.split[1]
-
-    # The default SMTP port number, 25.
-    def SMTP.default_port
-      25
-    end
-
-    # The default mail submission port number, 587.
-    def SMTP.default_submission_port
-      587
-    end
-
-    # The default SMTPS port number, 465.
-    def SMTP.default_tls_port
-      465
-    end
-
-    class << self
-      alias default_ssl_port default_tls_port
-    end
-
-    def SMTP.default_ssl_context
-      OpenSSL::SSL::SSLContext.new
-    end
-
-    #
-    # Creates a new Net::SMTP object.
-    #
-    # +address+ is the hostname or ip address of your SMTP
-    # server.  +port+ is the port to connect to; it defaults to
-    # port 25.
-    #
-    # This method does not open the TCP connection.  You can use
-    # SMTP.start instead of SMTP.new if you want to do everything
-    # at once.  Otherwise, follow SMTP.new with SMTP#start.
-    #
-    def initialize(address, port = nil)
-      @address = address
-      @port = (port || SMTP.default_port)
-      @esmtp = true
-      @capabilities = nil
-      @socket = nil
-      @started = false
-      @open_timeout = 30
-      @read_timeout = 60
-      @error_occured = false
-      @debug_output = nil
-      @tls = false
-      @starttls = false
-      @ssl_context = nil
-    end
-
-    # Provide human-readable stringification of class state.
-    def inspect
-      "#<#{self.class} #{@address}:#{@port} started=#{@started}>"
-    end
-
-    #
-    # Set whether to use ESMTP or not.  This should be done before
-    # calling #start.  Note that if #start is called in ESMTP mode,
-    # and the connection fails due to a ProtocolError, the SMTP
-    # object will automatically switch to plain SMTP mode and
-    # retry (but not vice versa).
-    #
-    attr_accessor :esmtp
-
-    # +true+ if the SMTP object uses ESMTP (which it does by default).
-    alias :esmtp? :esmtp
-
-    # true if server advertises STARTTLS.
-    # You cannot get valid value before opening SMTP session.
-    def capable_starttls?
-      capable?('STARTTLS')
-    end
-
-    def capable?(key)
-      return nil unless @capabilities
-      @capabilities[key] ? true : false
-    end
-    private :capable?
-
-    # true if server advertises AUTH PLAIN.
-    # You cannot get valid value before opening SMTP session.
-    def capable_plain_auth?
-      auth_capable?('PLAIN')
-    end
-
-    # true if server advertises AUTH LOGIN.
-    # You cannot get valid value before opening SMTP session.
-    def capable_login_auth?
-      auth_capable?('LOGIN')
-    end
-
-    # true if server advertises AUTH CRAM-MD5.
-    # You cannot get valid value before opening SMTP session.
-    def capable_cram_md5_auth?
-      auth_capable?('CRAM-MD5')
-    end
-
-    def auth_capable?(type)
-      return nil unless @capabilities
-      return false unless @capabilities['AUTH']
-      @capabilities['AUTH'].include?(type)
-    end
-    private :auth_capable?
-
-    # Returns supported authentication methods on this server.
-    # You cannot get valid value before opening SMTP session.
-    def capable_auth_types
-      return [] unless @capabilities
-      return [] unless @capabilities['AUTH']
-      @capabilities['AUTH']
-    end
-
-    # true if this object uses SMTP/TLS (SMTPS).
-    def tls?
-      @tls
-    end
-
-    alias ssl? tls?
-
-    # Enables SMTP/TLS (SMTPS: SMTP over direct TLS connection) for
-    # this object.  Must be called before the connection is established
-    # to have any effect.  +context+ is a OpenSSL::SSL::SSLContext object.
-    def enable_tls(context = SMTP.default_ssl_context)
-      raise 'openssl library not installed' unless defined?(OpenSSL)
-      raise ArgumentError, "SMTPS and STARTTLS is exclusive" if @starttls
-      @tls = true
-      @ssl_context = context
-    end
-
-    alias enable_ssl enable_tls
-
-    # Disables SMTP/TLS for this object.  Must be called before the
-    # connection is established to have any effect.
-    def disable_tls
-      @tls = false
-      @ssl_context = nil
-    end
-
-    alias disable_ssl disable_tls
-
-    # Returns truth value if this object uses STARTTLS.
-    # If this object always uses STARTTLS, returns :always.
-    # If this object uses STARTTLS when the server support TLS, returns :auto.
-    def starttls?
-      @starttls
-    end
-
-    # true if this object uses STARTTLS.
-    def starttls_always?
-      @starttls == :always
-    end
-
-    # true if this object uses STARTTLS when server advertises STARTTLS.
-    def starttls_auto?
-      @starttls == :auto
-    end
-
-    # Enables SMTP/TLS (STARTTLS) for this object.
-    # +context+ is a OpenSSL::SSL::SSLContext object.
-    def enable_starttls(context = SMTP.default_ssl_context)
-      raise 'openssl library not installed' unless defined?(OpenSSL)
-      raise ArgumentError, "SMTPS and STARTTLS is exclusive" if @tls
-      @starttls = :always
-      @ssl_context = context
-    end
-
-    # Enables SMTP/TLS (STARTTLS) for this object if server accepts.
-    # +context+ is a OpenSSL::SSL::SSLContext object.
-    def enable_starttls_auto(context = SMTP.default_ssl_context)
-      raise 'openssl library not installed' unless defined?(OpenSSL)
-      raise ArgumentError, "SMTPS and STARTTLS is exclusive" if @tls
-      @starttls = :auto
-      @ssl_context = context
-    end
-
-    # Disables SMTP/TLS (STARTTLS) for this object.  Must be called
-    # before the connection is established to have any effect.
-    def disable_starttls
-      @starttls = false
-      @ssl_context = nil
-    end
-
-    # The address of the SMTP server to connect to.
-    attr_reader :address
-
-    # The port number of the SMTP server to connect to.
-    attr_reader :port
-
-    # Seconds to wait while attempting to open a connection.
-    # If the connection cannot be opened within this time, a
-    # TimeoutError is raised. The default value is 30 seconds.
-    attr_accessor :open_timeout
-
-    # Seconds to wait while reading one block (by one read(2) call).
-    # If the read(2) call does not complete within this time, a
-    # TimeoutError is raised. The default value is 60 seconds.
-    attr_reader :read_timeout
-
-    # Set the number of seconds to wait until timing-out a read(2)
-    # call.
-    def read_timeout=(sec)
-      @socket.read_timeout = sec if @socket
-      @read_timeout = sec
-    end
-
-    #
-    # WARNING: This method causes serious security holes.
-    # Use this method for only debugging.
-    #
-    # Set an output stream for debug logging.
-    # You must call this before #start.
-    #
-    #   # example
-    #   smtp = Net::SMTP.new(addr, port)
-    #   smtp.set_debug_output $stderr
-    #   smtp.start do |smtp|
-    #     ....
-    #   end
-    #
-    def debug_output=(arg)
-      @debug_output = arg
-    end
-
-    alias set_debug_output debug_output=
-
-    #
-    # SMTP session control
-    #
-
-    #
-    # Creates a new Net::SMTP object and connects to the server.
-    #
-    # This method is equivalent to:
-    #
-    #   Net::SMTP.new(address, port).start(helo_domain, account, password, authtype)
-    #
-    # === Example
-    #
-    #     Net::SMTP.start('your.smtp.server') do |smtp|
-    #       smtp.send_message msgstr, 'from@example.com', ['dest@example.com']
-    #     end
-    #
-    # === Block Usage
-    #
-    # If called with a block, the newly-opened Net::SMTP object is yielded
-    # to the block, and automatically closed when the block finishes.  If called
-    # without a block, the newly-opened Net::SMTP object is returned to
-    # the caller, and it is the caller's responsibility to close it when
-    # finished.
-    #
-    # === Parameters
-    #
-    # +address+ is the hostname or ip address of your smtp server.
-    #
-    # +port+ is the port to connect to; it defaults to port 25.
-    #
-    # +helo+ is the _HELO_ _domain_ provided by the client to the
-    # server (see overview comments); it defaults to 'localhost'.
-    #
-    # The remaining arguments are used for SMTP authentication, if required
-    # or desired.  +user+ is the account name; +secret+ is your password
-    # or other authentication token; and +authtype+ is the authentication
-    # type, one of :plain, :login, or :cram_md5.  See the discussion of
-    # SMTP Authentication in the overview notes.
-    #
-    # === Errors
-    #
-    # This method may raise:
-    #
-    # * Net::SMTPAuthenticationError
-    # * Net::SMTPServerBusy
-    # * Net::SMTPSyntaxError
-    # * Net::SMTPFatalError
-    # * Net::SMTPUnknownError
-    # * IOError
-    # * TimeoutError
-    #
-    def SMTP.start(address, port = nil, helo = 'localhost',
-                   user = nil, secret = nil, authtype = nil,
-                   &block)   # :yield: smtp
-      new(address, port).start(helo, user, secret, authtype, &block)
-    end
-
-    # +true+ if the SMTP session has been started.
-    def started?
-      @started
-    end
-
-    #
-    # Opens a TCP connection and starts the SMTP session.
-    #
-    # === Parameters
-    #
-    # +helo+ is the _HELO_ _domain_ that you'll dispatch mails from; see
-    # the discussion in the overview notes.
-    #
-    # If both of +user+ and +secret+ are given, SMTP authentication
-    # will be attempted using the AUTH command.  +authtype+ specifies
-    # the type of authentication to attempt; it must be one of
-    # :login, :plain, and :cram_md5.  See the notes on SMTP Authentication
-    # in the overview.
-    #
-    # === Block Usage
-    #
-    # When this methods is called with a block, the newly-started SMTP
-    # object is yielded to the block, and automatically closed after
-    # the block call finishes.  Otherwise, it is the caller's
-    # responsibility to close the session when finished.
-    #
-    # === Example
-    #
-    # This is very similar to the class method SMTP.start.
-    #
-    #     require 'net/smtp'
-    #     smtp = Net::SMTP.new('smtp.mail.server', 25)
-    #     smtp.start(helo_domain, account, password, authtype) do |smtp|
-    #       smtp.send_message msgstr, 'from@example.com', ['dest@example.com']
-    #     end
-    #
-    # The primary use of this method (as opposed to SMTP.start)
-    # is probably to set debugging (#set_debug_output) or ESMTP
-    # (#esmtp=), which must be done before the session is
-    # started.
-    #
-    # === Errors
-    #
-    # If session has already been started, an IOError will be raised.
-    #
-    # This method may raise:
-    #
-    # * Net::SMTPAuthenticationError
-    # * Net::SMTPServerBusy
-    # * Net::SMTPSyntaxError
-    # * Net::SMTPFatalError
-    # * Net::SMTPUnknownError
-    # * IOError
-    # * TimeoutError
-    #
-    def start(helo = 'localhost',
-              user = nil, secret = nil, authtype = nil)   # :yield: smtp
-      if block_given?
-        begin
-          do_start helo, user, secret, authtype
-          return yield(self)
-        ensure
-          do_finish
-        end
-      else
-        do_start helo, user, secret, authtype
-        return self
-      end
-    end
-
-    # Finishes the SMTP session and closes TCP connection.
-    # Raises IOError if not started.
-    def finish
-      raise IOError, 'not yet started' unless started?
-      do_finish
-    end
-
-    private
-
-    def tcp_socket(address, port)
-      TCPSocket.open address, port
-    end
-
-    def do_start(helo_domain, user, secret, authtype)
-      raise IOError, 'SMTP session already started' if @started
-      if user or secret
-        check_auth_method(authtype || DEFAULT_AUTH_TYPE)
-        check_auth_args user, secret
-      end
-      s = timeout(@open_timeout) { tcp_socket(@address, @port) }
-      logging "Connection opened: #{@address}:#{@port}"
-      @socket = new_internet_message_io(tls? ? tlsconnect(s) : s)
-      check_response critical { recv_response() }
-      do_helo helo_domain
-      if starttls_always? or (capable_starttls? and starttls_auto?)
-        unless capable_starttls?
-          raise SMTPUnsupportedCommand,
-              "STARTTLS is not supported on this server"
-        end
-        starttls
-        @socket = new_internet_message_io(tlsconnect(s))
-        # helo response may be different after STARTTLS
-        do_helo helo_domain
-      end
-      authenticate user, secret, (authtype || DEFAULT_AUTH_TYPE) if user
-      @started = true
-    ensure
-      unless @started
-        # authentication failed, cancel connection.
-        s.close if s and not s.closed?
-        @socket = nil
-      end
-    end
-
-    def ssl_socket(socket, context)
-      OpenSSL::SSL::SSLSocket.new socket, context
-    end
-
-    def tlsconnect(s)
-      verified = false
-      s = ssl_socket(s, @ssl_context)
-      logging "TLS connection started"
-      s.sync_close = true
-      s.connect
-      if @ssl_context.verify_mode != OpenSSL::SSL::VERIFY_NONE
-        s.post_connection_check(@address)
-      end
-      verified = true
-      s
-    ensure
-      s.close unless verified
-    end
-
-    def new_internet_message_io(s)
-      io = InternetMessageIO.new(s)
-      io.read_timeout = @read_timeout
-      io.debug_output = @debug_output
-      io
-    end
-
-    def do_helo(helo_domain)
-      res = @esmtp ? ehlo(helo_domain) : helo(helo_domain)
-      @capabilities = res.capabilities
-    rescue SMTPError
-      if @esmtp
-        @esmtp = false
-        @error_occured = false
-        retry
-      end
-      raise
-    end
-
-    def do_finish
-      quit if @socket and not @socket.closed? and not @error_occured
-    ensure
-      @started = false
-      @error_occured = false
-      @socket.close if @socket and not @socket.closed?
-      @socket = nil
-    end
-
-    #
-    # Message Sending
-    #
-
-    public
-
-    #
-    # Sends +msgstr+ as a message.  Single CR ("\r") and LF ("\n") found
-    # in the +msgstr+, are converted into the CR LF pair.  You cannot send a
-    # binary message with this method. +msgstr+ should include both
-    # the message headers and body.
-    #
-    # +from_addr+ is a String representing the source mail address.
-    #
-    # +to_addr+ is a String or Strings or Array of Strings, representing
-    # the destination mail address or addresses.
-    #
-    # === Example
-    #
-    #     Net::SMTP.start('smtp.example.com') do |smtp|
-    #       smtp.send_message msgstr,
-    #                         'from@example.com',
-    #                         ['dest@example.com', 'dest2@example.com']
-    #     end
-    #
-    # === Errors
-    #
-    # This method may raise:
-    #
-    # * Net::SMTPServerBusy
-    # * Net::SMTPSyntaxError
-    # * Net::SMTPFatalError
-    # * Net::SMTPUnknownError
-    # * IOError
-    # * TimeoutError
-    #
-    def send_message(msgstr, from_addr, *to_addrs)
-      raise IOError, 'closed session' unless @socket
-      mailfrom from_addr
-      rcptto_list(to_addrs) {data msgstr}
-    end
-
-    alias send_mail send_message
-    alias sendmail send_message   # obsolete
-
-    #
-    # Opens a message writer stream and gives it to the block.
-    # The stream is valid only in the block, and has these methods:
-    #
-    # puts(str = '')::       outputs STR and CR LF.
-    # print(str)::           outputs STR.
-    # printf(fmt, *args)::   outputs sprintf(fmt,*args).
-    # write(str)::           outputs STR and returns the length of written bytes.
-    # <<(str)::              outputs STR and returns self.
-    #
-    # If a single CR ("\r") or LF ("\n") is found in the message,
-    # it is converted to the CR LF pair.  You cannot send a binary
-    # message with this method.
-    #
-    # === Parameters
-    #
-    # +from_addr+ is a String representing the source mail address.
-    #
-    # +to_addr+ is a String or Strings or Array of Strings, representing
-    # the destination mail address or addresses.
-    #
-    # === Example
-    #
-    #     Net::SMTP.start('smtp.example.com', 25) do |smtp|
-    #       smtp.open_message_stream('from@example.com', ['dest@example.com']) do |f|
-    #         f.puts 'From: from@example.com'
-    #         f.puts 'To: dest@example.com'
-    #         f.puts 'Subject: test message'
-    #         f.puts
-    #         f.puts 'This is a test message.'
-    #       end
-    #     end
-    #
-    # === Errors
-    #
-    # This method may raise:
-    #
-    # * Net::SMTPServerBusy
-    # * Net::SMTPSyntaxError
-    # * Net::SMTPFatalError
-    # * Net::SMTPUnknownError
-    # * IOError
-    # * TimeoutError
-    #
-    def open_message_stream(from_addr, *to_addrs, &block)   # :yield: stream
-      raise IOError, 'closed session' unless @socket
-      mailfrom from_addr
-      rcptto_list(to_addrs) {data(&block)}
-    end
-
-    alias ready open_message_stream   # obsolete
-
-    #
-    # Authentication
-    #
-
-    public
-
-    DEFAULT_AUTH_TYPE = :plain
-
-    def authenticate(user, secret, authtype = DEFAULT_AUTH_TYPE)
-      check_auth_method authtype
-      check_auth_args user, secret
-      send auth_method(authtype), user, secret
-    end
-
-    def auth_plain(user, secret)
-      check_auth_args user, secret
-      res = critical {
-        get_response('AUTH PLAIN ' + base64_encode("\0#{user}\0#{secret}"))
-      }
-      check_auth_response res
-      res
-    end
-
-    def auth_login(user, secret)
-      check_auth_args user, secret
-      res = critical {
-        check_auth_continue get_response('AUTH LOGIN')
-        check_auth_continue get_response(base64_encode(user))
-        get_response(base64_encode(secret))
-      }
-      check_auth_response res
-      res
-    end
-
-    def auth_cram_md5(user, secret)
-      check_auth_args user, secret
-      res = critical {
-        res0 = get_response('AUTH CRAM-MD5')
-        check_auth_continue res0
-        crammed = cram_md5_response(secret, res0.cram_md5_challenge)
-        get_response(base64_encode("#{user} #{crammed}"))
-      }
-      check_auth_response res
-      res
-    end
-
-    private
-
-    def check_auth_method(type)
-      unless respond_to?(auth_method(type), true)
-        raise ArgumentError, "wrong authentication type #{type}"
-      end
-    end
-
-    def auth_method(type)
-      "auth_#{type.to_s.downcase}".intern
-    end
-
-    def check_auth_args(user, secret, authtype = DEFAULT_AUTH_TYPE)
-      unless user
-        raise ArgumentError, 'SMTP-AUTH requested but missing user name'
-      end
-      unless secret
-        raise ArgumentError, 'SMTP-AUTH requested but missing secret phrase'
-      end
-    end
-
-    def base64_encode(str)
-      # expects "str" may not become too long
-      [str].pack('m').gsub(/\s+/, '')
-    end
-
-    IMASK = 0x36
-    OMASK = 0x5c
-
-    # CRAM-MD5: [RFC2195]
-    def cram_md5_response(secret, challenge)
-      tmp = Digest::MD5.digest(cram_secret(secret, IMASK) + challenge)
-      Digest::MD5.hexdigest(cram_secret(secret, OMASK) + tmp)
-    end
-
-    CRAM_BUFSIZE = 64
-
-    def cram_secret(secret, mask)
-      secret = Digest::MD5.digest(secret) if secret.size > CRAM_BUFSIZE
-      buf = secret.ljust(CRAM_BUFSIZE, "\0")
-      0.upto(buf.size - 1) do |i|
-        buf[i] = (buf[i].ord ^ mask).chr
-      end
-      buf
-    end
-
-    #
-    # SMTP command dispatcher
-    #
-
-    public
-
-    def starttls
-      getok('STARTTLS')
-    end
-
-    def helo(domain)
-      getok("HELO #{domain}")
-    end
-
-    def ehlo(domain)
-      getok("EHLO #{domain}")
-    end
-
-    def mailfrom(from_addr)
-      if $SAFE > 0
-        raise SecurityError, 'tainted from_addr' if from_addr.tainted?
-      end
-      getok("MAIL FROM:<#{from_addr}>")
-    end
-
-    def rcptto_list(to_addrs)
-      raise ArgumentError, 'mail destination not given' if to_addrs.empty?
-      ok_users = []
-      unknown_users = []
-      to_addrs.flatten.each do |addr|
-        begin
-          rcptto addr
-        rescue SMTPAuthenticationError
-          unknown_users << addr.dump
-        else
-          ok_users << addr
-        end
-      end
-      raise ArgumentError, 'mail destination not given' if ok_users.empty?
-      ret = yield
-      unless unknown_users.empty?
-        raise SMTPAuthenticationError, "failed to deliver for #{unknown_users.join(', ')}"
-      end
-      ret
-    end
-
-    def rcptto(to_addr)
-      if $SAFE > 0
-        raise SecurityError, 'tainted to_addr' if to_addr.tainted?
-      end
-      getok("RCPT TO:<#{to_addr}>")
-    end
-
-    # This method sends a message.
-    # If +msgstr+ is given, sends it as a message.
-    # If block is given, yield a message writer stream.
-    # You must write message before the block is closed.
-    #
-    #   # Example 1 (by string)
-    #   smtp.data(<<EndMessage)
-    #   From: john@example.com
-    #   To: betty@example.com
-    #   Subject: I found a bug
-    #
-    #   Check vm.c:58879.
-    #   EndMessage
-    #
-    #   # Example 2 (by block)
-    #   smtp.data {|f|
-    #     f.puts "From: john@example.com"
-    #     f.puts "To: betty@example.com"
-    #     f.puts "Subject: I found a bug"
-    #     f.puts ""
-    #     f.puts "Check vm.c:58879."
-    #   }
-    #
-    def data(msgstr = nil, &block)   #:yield: stream
-      if msgstr and block
-        raise ArgumentError, "message and block are exclusive"
-      end
-      unless msgstr or block
-        raise ArgumentError, "message or block is required"
-      end
-      res = critical {
-        check_continue get_response('DATA')
-        if msgstr
-          @socket.write_message msgstr
-        else
-          @socket.write_message_by_block(&block)
-        end
-        recv_response()
-      }
-      check_response res
-      res
-    end
-
-    def quit
-      getok('QUIT')
-    end
-
-    private
-
-    def getok(reqline)
-      res = critical {
-        @socket.writeline reqline
-        recv_response()
-      }
-      check_response res
-      res
-    end
-
-    def get_response(reqline)
-      @socket.writeline reqline
-      recv_response()
-    end
-
-    def recv_response
-      buf = ''
-      while true
-        line = @socket.readline
-        buf << line << "\n"
-        break unless line[3,1] == '-'   # "210-PIPELINING"
-      end
-      Response.parse(buf)
-    end
-
-    def critical(&block)
-      return Response.parse('200 dummy reply code') if @error_occurred
-      begin
-        return yield()
-      rescue Exception
-        @error_occurred = true
-        raise
-      end
-    end
-
-    def check_response(res)
-      unless res.success?
-        raise res.exception_class, res.message
-      end
-    end
-
-    def check_continue(res)
-      unless res.continue?
-        raise SMTPUnknownError, "could not get 3xx (#{res.status})"
-      end
-    end
-
-    def check_auth_response(res)
-      unless res.success?
-        raise SMTPAuthenticationError, res.message
-      end
-    end
-
-    def check_auth_continue(res)
-      unless res.continue?
-        raise res.exception_class, res.message
-      end
-    end
-
-    # This class represents a response received by the SMTP server. Instances
-    # of this class are created by the SMTP class; they should not be directly
-    # created by the user. For more information on SMTP responses, view
-    # {Section 4.2 of RFC 5321}[http://tools.ietf.org/html/rfc5321#section-4.2]
-    class Response
-      # Parses the received response and separates the reply code and the human
-      # readable reply text
-      def self.parse(str)
-        new(str[0,3], str)
-      end
-
-      # Creates a new instance of the Response class and sets the status and
-      # string attributes
-      def initialize(status, string)
-        @status = status
-        @string = string
-      end
-
-      # The three digit reply code of the SMTP response
-      attr_reader :status
-
-      # The human readable reply text of the SMTP response
-      attr_reader :string
-
-      # Takes the first digit of the reply code to determine the status type
-      def status_type_char
-        @status[0, 1]
-      end
-
-      # Determines whether the response received was a Positive Completion
-      # reply (2xx reply code)
-      def success?
-        status_type_char() == '2'
-      end
-
-      # Determines whether the response received was a Positive Intermediate
-      # reply (3xx reply code)
-      def continue?
-        status_type_char() == '3'
-      end
-
-      # The first line of the human readable reply text
-      def message
-        @string.lines.first
-      end
-
-      # Creates a CRAM-MD5 challenge. You can view more information on CRAM-MD5
-      # on Wikipedia: http://en.wikipedia.org/wiki/CRAM-MD5
-      def cram_md5_challenge
-        @string.split(/ /)[1].unpack('m')[0]
-      end
-
-      # Returns a hash of the human readable reply text in the response if it
-      # is multiple lines. It does not return the first line. The key of the
-      # hash is the first word the value of the hash is an array with each word
-      # thereafter being a value in the array
-      def capabilities
-        return {} unless @string[3, 1] == '-'
-        h = {}
-        @string.lines.drop(1).each do |line|
-          k, *v = line[4..-1].chomp.split
-          h[k] = v
-        end
-        h
-      end
-
-      # Determines whether there was an error and raies the appropriate error
-      # based on the reply code of the response
-      def exception_class
-        case @status
-        when /\A4/  then SMTPServerBusy
-        when /\A50/ then SMTPSyntaxError
-        when /\A53/ then SMTPAuthenticationError
-        when /\A5/  then SMTPFatalError
-        else             SMTPUnknownError
-        end
-      end
-    end
-
-    def logging(msg)
-      @debug_output << msg + "\n" if @debug_output
-    end
-
-  end   # class SMTP
-
-  SMTPSession = SMTP
-
-end
diff --git a/lib/net/telnet.rb b/lib/net/telnet.rb
deleted file mode 100644
index fe463c63dc..0000000000
--- a/lib/net/telnet.rb
+++ /dev/null
@@ -1,764 +0,0 @@
-# = net/telnet.rb - Simple Telnet Client Library
-#
-# Author:: Wakou Aoyama <wakou@ruby-lang.org>
-# Documentation:: William Webber and Wakou Aoyama
-#
-# This file holds the class Net::Telnet, which provides client-side
-# telnet functionality.
-#
-# For documentation, see Net::Telnet.
-#
-
-require "socket"
-require "timeout"
-require "English"
-
-module Net
-
-  #
-  # == Net::Telnet
-  #
-  # Provides telnet client functionality.
-  #
-  # This class also has, through delegation, all the methods of a
-  # socket object (by default, a +TCPSocket+, but can be set by the
-  # +Proxy+ option to <tt>new()</tt>).  This provides methods such as
-  # <tt>close()</tt> to end the session and <tt>sysread()</tt> to read
-  # data directly from the host, instead of via the <tt>waitfor()</tt>
-  # mechanism.  Note that if you do use <tt>sysread()</tt> directly
-  # when in telnet mode, you should probably pass the output through
-  # <tt>preprocess()</tt> to extract telnet command sequences.
-  #
-  # == Overview
-  #
-  # The telnet protocol allows a client to login remotely to a user
-  # account on a server and execute commands via a shell.  The equivalent
-  # is done by creating a Net::Telnet class with the +Host+ option
-  # set to your host, calling #login() with your user and password,
-  # issuing one or more #cmd() calls, and then calling #close()
-  # to end the session.  The #waitfor(), #print(), #puts(), and
-  # #write() methods, which #cmd() is implemented on top of, are
-  # only needed if you are doing something more complicated.
-  #
-  # A Net::Telnet object can also be used to connect to non-telnet
-  # services, such as SMTP or HTTP.  In this case, you normally
-  # want to provide the +Port+ option to specify the port to
-  # connect to, and set the +Telnetmode+ option to false to prevent
-  # the client from attempting to interpret telnet command sequences.
-  # Generally, #login() will not work with other protocols, and you
-  # have to handle authentication yourself.
-  #
-  # For some protocols, it will be possible to specify the +Prompt+
-  # option once when you create the Telnet object and use #cmd() calls;
-  # for others, you will have to specify the response sequence to
-  # look for as the Match option to every #cmd() call, or call
-  # #puts() and #waitfor() directly; for yet others, you will have
-  # to use #sysread() instead of #waitfor() and parse server
-  # responses yourself.
-  #
-  # It is worth noting that when you create a new Net::Telnet object,
-  # you can supply a proxy IO channel via the Proxy option.  This
-  # can be used to attach the Telnet object to other Telnet objects,
-  # to already open sockets, or to any read-write IO object.  This
-  # can be useful, for instance, for setting up a test fixture for
-  # unit testing.
-  #
-  # == Examples
-  #
-  # === Log in and send a command, echoing all output to stdout
-  #
-  #   localhost = Net::Telnet::new("Host" => "localhost",
-  #                                "Timeout" => 10,
-  #                                "Prompt" => /[$%#>] \z/n)
-  #   localhost.login("username", "password") { |c| print c }
-  #   localhost.cmd("command") { |c| print c }
-  #   localhost.close
-  #
-  #
-  # === Check a POP server to see if you have mail
-  #
-  #   pop = Net::Telnet::new("Host" => "your_destination_host_here",
-  #                          "Port" => 110,
-  #                          "Telnetmode" => false,
-  #                          "Prompt" => /^\+OK/n)
-  #   pop.cmd("user " + "your_username_here") { |c| print c }
-  #   pop.cmd("pass " + "your_password_here") { |c| print c }
-  #   pop.cmd("list") { |c| print c }
-  #
-  # == References
-  #
-  # There are a large number of RFCs relevant to the Telnet protocol.
-  # RFCs 854-861 define the base protocol.  For a complete listing
-  # of relevant RFCs, see
-  # http://www.omnifarious.org/~hopper/technical/telnet-rfc.html
-  #
-  class Telnet
-
-    # :stopdoc:
-    IAC   = 255.chr # "\377" # "\xff" # interpret as command
-    DONT  = 254.chr # "\376" # "\xfe" # you are not to use option
-    DO    = 253.chr # "\375" # "\xfd" # please, you use option
-    WONT  = 252.chr # "\374" # "\xfc" # I won't use option
-    WILL  = 251.chr # "\373" # "\xfb" # I will use option
-    SB    = 250.chr # "\372" # "\xfa" # interpret as subnegotiation
-    GA    = 249.chr # "\371" # "\xf9" # you may reverse the line
-    EL    = 248.chr # "\370" # "\xf8" # erase the current line
-    EC    = 247.chr # "\367" # "\xf7" # erase the current character
-    AYT   = 246.chr # "\366" # "\xf6" # are you there
-    AO    = 245.chr # "\365" # "\xf5" # abort output--but let prog finish
-    IP    = 244.chr # "\364" # "\xf4" # interrupt process--permanently
-    BREAK = 243.chr # "\363" # "\xf3" # break
-    DM    = 242.chr # "\362" # "\xf2" # data mark--for connect. cleaning
-    NOP   = 241.chr # "\361" # "\xf1" # nop
-    SE    = 240.chr # "\360" # "\xf0" # end sub negotiation
-    EOR   = 239.chr # "\357" # "\xef" # end of record (transparent mode)
-    ABORT = 238.chr # "\356" # "\xee" # Abort process
-    SUSP  = 237.chr # "\355" # "\xed" # Suspend process
-    EOF   = 236.chr # "\354" # "\xec" # End of file
-    SYNCH = 242.chr # "\362" # "\xf2" # for telfunc calls
-
-    OPT_BINARY         =   0.chr # "\000" # "\x00" # Binary Transmission
-    OPT_ECHO           =   1.chr # "\001" # "\x01" # Echo
-    OPT_RCP            =   2.chr # "\002" # "\x02" # Reconnection
-    OPT_SGA            =   3.chr # "\003" # "\x03" # Suppress Go Ahead
-    OPT_NAMS           =   4.chr # "\004" # "\x04" # Approx Message Size Negotiation
-    OPT_STATUS         =   5.chr # "\005" # "\x05" # Status
-    OPT_TM             =   6.chr # "\006" # "\x06" # Timing Mark
-    OPT_RCTE           =   7.chr # "\a"   # "\x07" # Remote Controlled Trans and Echo
-    OPT_NAOL           =   8.chr # "\010" # "\x08" # Output Line Width
-    OPT_NAOP           =   9.chr # "\t"   # "\x09" # Output Page Size
-    OPT_NAOCRD         =  10.chr # "\n"   # "\x0a" # Output Carriage-Return Disposition
-    OPT_NAOHTS         =  11.chr # "\v"   # "\x0b" # Output Horizontal Tab Stops
-    OPT_NAOHTD         =  12.chr # "\f"   # "\x0c" # Output Horizontal Tab Disposition
-    OPT_NAOFFD         =  13.chr # "\r"   # "\x0d" # Output Formfeed Disposition
-    OPT_NAOVTS         =  14.chr # "\016" # "\x0e" # Output Vertical Tabstops
-    OPT_NAOVTD         =  15.chr # "\017" # "\x0f" # Output Vertical Tab Disposition
-    OPT_NAOLFD         =  16.chr # "\020" # "\x10" # Output Linefeed Disposition
-    OPT_XASCII         =  17.chr # "\021" # "\x11" # Extended ASCII
-    OPT_LOGOUT         =  18.chr # "\022" # "\x12" # Logout
-    OPT_BM             =  19.chr # "\023" # "\x13" # Byte Macro
-    OPT_DET            =  20.chr # "\024" # "\x14" # Data Entry Terminal
-    OPT_SUPDUP         =  21.chr # "\025" # "\x15" # SUPDUP
-    OPT_SUPDUPOUTPUT   =  22.chr # "\026" # "\x16" # SUPDUP Output
-    OPT_SNDLOC         =  23.chr # "\027" # "\x17" # Send Location
-    OPT_TTYPE          =  24.chr # "\030" # "\x18" # Terminal Type
-    OPT_EOR            =  25.chr # "\031" # "\x19" # End of Record
-    OPT_TUID           =  26.chr # "\032" # "\x1a" # TACACS User Identification
-    OPT_OUTMRK         =  27.chr # "\e"   # "\x1b" # Output Marking
-    OPT_TTYLOC         =  28.chr # "\034" # "\x1c" # Terminal Location Number
-    OPT_3270REGIME     =  29.chr # "\035" # "\x1d" # Telnet 3270 Regime
-    OPT_X3PAD          =  30.chr # "\036" # "\x1e" # X.3 PAD
-    OPT_NAWS           =  31.chr # "\037" # "\x1f" # Negotiate About Window Size
-    OPT_TSPEED         =  32.chr # " "    # "\x20" # Terminal Speed
-    OPT_LFLOW          =  33.chr # "!"    # "\x21" # Remote Flow Control
-    OPT_LINEMODE       =  34.chr # "\""   # "\x22" # Linemode
-    OPT_XDISPLOC       =  35.chr # "#"    # "\x23" # X Display Location
-    OPT_OLD_ENVIRON    =  36.chr # "$"    # "\x24" # Environment Option
-    OPT_AUTHENTICATION =  37.chr # "%"    # "\x25" # Authentication Option
-    OPT_ENCRYPT        =  38.chr # "&"    # "\x26" # Encryption Option
-    OPT_NEW_ENVIRON    =  39.chr # "'"    # "\x27" # New Environment Option
-    OPT_EXOPL          = 255.chr # "\377" # "\xff" # Extended-Options-List
-
-    NULL = "\000"
-    CR   = "\015"
-    LF   = "\012"
-    EOL  = CR + LF
-    REVISION = '$Id$'
-    # :startdoc:
-
-    #
-    # Creates a new Net::Telnet object.
-    #
-    # Attempts to connect to the host (unless the Proxy option is
-    # provided: see below).  If a block is provided, it is yielded
-    # status messages on the attempt to connect to the server, of
-    # the form:
-    #
-    #   Trying localhost...
-    #   Connected to localhost.
-    #
-    # +options+ is a hash of options.  The following example lists
-    # all options and their default values.
-    #
-    #   host = Net::Telnet::new(
-    #            "Host"       => "localhost",  # default: "localhost"
-    #            "Port"       => 23,           # default: 23
-    #            "Binmode"    => false,        # default: false
-    #            "Output_log" => "output_log", # default: nil (no output)
-    #            "Dump_log"   => "dump_log",   # default: nil (no output)
-    #            "Prompt"     => /[$%#>] \z/n, # default: /[$%#>] \z/n
-    #            "Telnetmode" => true,         # default: true
-    #            "Timeout"    => 10,           # default: 10
-    #              # if ignore timeout then set "Timeout" to false.
-    #            "Waittime"   => 0,            # default: 0
-    #            "Proxy"      => proxy         # default: nil
-    #                            # proxy is Net::Telnet or IO object
-    #          )
-    #
-    # The options have the following meanings:
-    #
-    # Host:: the hostname or IP address of the host to connect to, as a String.
-    #        Defaults to "localhost".
-    #
-    # Port:: the port to connect to.  Defaults to 23.
-    #
-    # Binmode:: if false (the default), newline substitution is performed.
-    #           Outgoing LF is
-    #           converted to CRLF, and incoming CRLF is converted to LF.  If
-    #           true, this substitution is not performed.  This value can
-    #           also be set with the #binmode() method.  The
-    #           outgoing conversion only applies to the #puts() and #print()
-    #           methods, not the #write() method.  The precise nature of
-    #           the newline conversion is also affected by the telnet options
-    #           SGA and BIN.
-    #
-    # Output_log:: the name of the file to write connection status messages
-    #              and all received traffic to.  In the case of a proper
-    #              Telnet session, this will include the client input as
-    #              echoed by the host; otherwise, it only includes server
-    #              responses.  Output is appended verbatim to this file.
-    #              By default, no output log is kept.
-    #
-    # Dump_log:: as for Output_log, except that output is written in hexdump
-    #            format (16 bytes per line as hex pairs, followed by their
-    #            printable equivalent), with connection status messages
-    #            preceded by '#', sent traffic preceded by '>', and
-    #            received traffic preceded by '<'.  By default, not dump log
-    #            is kept.
-    #
-    # Prompt:: a regular expression matching the host's command-line prompt
-    #          sequence.  This is needed by the Telnet class to determine
-    #          when the output from a command has finished and the host is
-    #          ready to receive a new command.  By default, this regular
-    #          expression is /[$%#>] \z/n.
-    #
-    # Telnetmode:: a boolean value, true by default.  In telnet mode,
-    #              traffic received from the host is parsed for special
-    #              command sequences, and these sequences are escaped
-    #              in outgoing traffic sent using #puts() or #print()
-    #              (but not #write()).  If you are using the Net::Telnet
-    #              object to connect to a non-telnet service (such as
-    #              SMTP or POP), this should be set to "false" to prevent
-    #              undesired data corruption.  This value can also be set
-    #              by the #telnetmode() method.
-    #
-    # Timeout:: the number of seconds to wait before timing out both the
-    #           initial attempt to connect to host (in this constructor),
-    #           and all attempts to read data from the host (in #waitfor(),
-    #           #cmd(), and #login()).  Exceeding this timeout causes a
-    #           TimeoutError to be raised.  The default value is 10 seconds.
-    #           You can disable the timeout by setting this value to false.
-    #           In this case, the connect attempt will eventually timeout
-    #           on the underlying connect(2) socket call with an
-    #           Errno::ETIMEDOUT error (but generally only after a few
-    #           minutes), but other attempts to read data from the host
-    #           will hand indefinitely if no data is forthcoming.
-    #
-    # Waittime:: the amount of time to wait after seeing what looks like a
-    #            prompt (that is, received data that matches the Prompt
-    #            option regular expression) to see if more data arrives.
-    #            If more data does arrive in this time, Net::Telnet assumes
-    #            that what it saw was not really a prompt.  This is to try to
-    #            avoid false matches, but it can also lead to missing real
-    #            prompts (if, for instance, a background process writes to
-    #            the terminal soon after the prompt is displayed).  By
-    #            default, set to 0, meaning not to wait for more data.
-    #
-    # Proxy:: a proxy object to used instead of opening a direct connection
-    #         to the host.  Must be either another Net::Telnet object or
-    #         an IO object.  If it is another Net::Telnet object, this
-    #         instance will use that one's socket for communication.  If an
-    #         IO object, it is used directly for communication.  Any other
-    #         kind of object will cause an error to be raised.
-    #
-    def initialize(options) # :yield: mesg
-      @options = options
-      @options["Host"]       = "localhost"   unless @options.has_key?("Host")
-      @options["Port"]       = 23            unless @options.has_key?("Port")
-      @options["Prompt"]     = /[$%#>] \z/n  unless @options.has_key?("Prompt")
-      @options["Timeout"]    = 10            unless @options.has_key?("Timeout")
-      @options["Waittime"]   = 0             unless @options.has_key?("Waittime")
-      unless @options.has_key?("Binmode")
-        @options["Binmode"]    = false
-      else
-        unless (true == @options["Binmode"] or false == @options["Binmode"])
-          raise ArgumentError, "Binmode option must be true or false"
-        end
-      end
-
-      unless @options.has_key?("Telnetmode")
-        @options["Telnetmode"] = true
-      else
-        unless (true == @options["Telnetmode"] or false == @options["Telnetmode"])
-          raise ArgumentError, "Telnetmode option must be true or false"
-        end
-      end
-
-      @telnet_option = { "SGA" => false, "BINARY" => false }
-
-      if @options.has_key?("Output_log")
-        @log = File.open(@options["Output_log"], 'a+')
-        @log.sync = true
-        @log.binmode
-      end
-
-      if @options.has_key?("Dump_log")
-        @dumplog = File.open(@options["Dump_log"], 'a+')
-        @dumplog.sync = true
-        @dumplog.binmode
-        def @dumplog.log_dump(dir, x)  # :nodoc:
-          len = x.length
-          addr = 0
-          offset = 0
-          while 0 < len
-            if len < 16
-              line = x[offset, len]
-            else
-              line = x[offset, 16]
-            end
-            hexvals = line.unpack('H*')[0]
-            hexvals += ' ' * (32 - hexvals.length)
-            hexvals = format("%s %s %s %s  " * 4, *hexvals.unpack('a2' * 16))
-            line = line.gsub(/[\000-\037\177-\377]/n, '.')
-            printf "%s 0x%5.5x: %s%s\n", dir, addr, hexvals, line
-            addr += 16
-            offset += 16
-            len -= 16
-          end
-          print "\n"
-        end
-      end
-
-      if @options.has_key?("Proxy")
-        if @options["Proxy"].kind_of?(Net::Telnet)
-          @sock = @options["Proxy"].sock
-        elsif @options["Proxy"].kind_of?(IO)
-          @sock = @options["Proxy"]
-        else
-          raise "Error: Proxy must be an instance of Net::Telnet or IO."
-        end
-      else
-        message = "Trying " + @options["Host"] + "...\n"
-        yield(message) if block_given?
-        @log.write(message) if @options.has_key?("Output_log")
-        @dumplog.log_dump('#', message) if @options.has_key?("Dump_log")
-
-        begin
-          if @options["Timeout"] == false
-            @sock = TCPSocket.open(@options["Host"], @options["Port"])
-          else
-            timeout(@options["Timeout"]) do
-              @sock = TCPSocket.open(@options["Host"], @options["Port"])
-            end
-          end
-        rescue TimeoutError
-          raise TimeoutError, "timed out while opening a connection to the host"
-        rescue
-          @log.write($ERROR_INFO.to_s + "\n") if @options.has_key?("Output_log")
-          @dumplog.log_dump('#', $ERROR_INFO.to_s + "\n") if @options.has_key?("Dump_log")
-          raise
-        end
-        @sock.sync = true
-        @sock.binmode
-
-        message = "Connected to " + @options["Host"] + ".\n"
-        yield(message) if block_given?
-        @log.write(message) if @options.has_key?("Output_log")
-        @dumplog.log_dump('#', message) if @options.has_key?("Dump_log")
-      end
-
-    end # initialize
-
-    # The socket the Telnet object is using.  Note that this object becomes
-    # a delegate of the Telnet object, so normally you invoke its methods
-    # directly on the Telnet object.
-    attr :sock
-
-    # Set telnet command interpretation on (+mode+ == true) or off
-    # (+mode+ == false), or return the current value (+mode+ not
-    # provided).  It should be on for true telnet sessions, off if
-    # using Net::Telnet to connect to a non-telnet service such
-    # as SMTP.
-    def telnetmode(mode = nil)
-      case mode
-      when nil
-        @options["Telnetmode"]
-      when true, false
-        @options["Telnetmode"] = mode
-      else
-        raise ArgumentError, "argument must be true or false, or missing"
-      end
-    end
-
-    # Turn telnet command interpretation on (true) or off (false).  It
-    # should be on for true telnet sessions, off if using Net::Telnet
-    # to connect to a non-telnet service such as SMTP.
-    def telnetmode=(mode)
-      if (true == mode or false == mode)
-        @options["Telnetmode"] = mode
-      else
-        raise ArgumentError, "argument must be true or false"
-      end
-    end
-
-    # Turn newline conversion on (+mode+ == false) or off (+mode+ == true),
-    # or return the current value (+mode+ is not specified).
-    def binmode(mode = nil)
-      case mode
-      when nil
-        @options["Binmode"]
-      when true, false
-        @options["Binmode"] = mode
-      else
-        raise ArgumentError, "argument must be true or false"
-      end
-    end
-
-    # Turn newline conversion on (false) or off (true).
-    def binmode=(mode)
-      if (true == mode or false == mode)
-        @options["Binmode"] = mode
-      else
-        raise ArgumentError, "argument must be true or false"
-      end
-    end
-
-    # Preprocess received data from the host.
-    #
-    # Performs newline conversion and detects telnet command sequences.
-    # Called automatically by #waitfor().  You should only use this
-    # method yourself if you have read input directly using sysread()
-    # or similar, and even then only if in telnet mode.
-    def preprocess(string)
-      # combine CR+NULL into CR
-      string = string.gsub(/#{CR}#{NULL}/no, CR) if @options["Telnetmode"]
-
-      # combine EOL into "\n"
-      string = string.gsub(/#{EOL}/no, "\n") unless @options["Binmode"]
-
-      # remove NULL
-      string = string.gsub(/#{NULL}/no, '') unless @options["Binmode"]
-
-      string.gsub(/#{IAC}(
-                   [#{IAC}#{AO}#{AYT}#{DM}#{IP}#{NOP}]|
-                   [#{DO}#{DONT}#{WILL}#{WONT}]
-                     [#{OPT_BINARY}-#{OPT_NEW_ENVIRON}#{OPT_EXOPL}]|
-                   #{SB}[^#{IAC}]*#{IAC}#{SE}
-                 )/xno) do
-        if    IAC == $1  # handle escaped IAC characters
-          IAC
-        elsif AYT == $1  # respond to "IAC AYT" (are you there)
-          self.write("nobody here but us pigeons" + EOL)
-          ''
-        elsif DO[0] == $1[0]  # respond to "IAC DO x"
-          if OPT_BINARY[0] == $1[1]
-            @telnet_option["BINARY"] = true
-            self.write(IAC + WILL + OPT_BINARY)
-          else
-            self.write(IAC + WONT + $1[1..1])
-          end
-          ''
-        elsif DONT[0] == $1[0]  # respond to "IAC DON'T x" with "IAC WON'T x"
-          self.write(IAC + WONT + $1[1..1])
-          ''
-        elsif WILL[0] == $1[0]  # respond to "IAC WILL x"
-          if    OPT_BINARY[0] == $1[1]
-            self.write(IAC + DO + OPT_BINARY)
-          elsif OPT_ECHO[0] == $1[1]
-            self.write(IAC + DO + OPT_ECHO)
-          elsif OPT_SGA[0]  == $1[1]
-            @telnet_option["SGA"] = true
-            self.write(IAC + DO + OPT_SGA)
-          else
-            self.write(IAC + DONT + $1[1..1])
-          end
-          ''
-        elsif WONT[0] == $1[0]  # respond to "IAC WON'T x"
-          if    OPT_ECHO[0] == $1[1]
-            self.write(IAC + DONT + OPT_ECHO)
-          elsif OPT_SGA[0]  == $1[1]
-            @telnet_option["SGA"] = false
-            self.write(IAC + DONT + OPT_SGA)
-          else
-            self.write(IAC + DONT + $1[1..1])
-          end
-          ''
-        else
-          ''
-        end
-      end
-    end # preprocess
-
-    # Read data from the host until a certain sequence is matched.
-    #
-    # If a block is given, the received data will be yielded as it
-    # is read in (not necessarily all in one go), or nil if EOF
-    # occurs before any data is received.  Whether a block is given
-    # or not, all data read will be returned in a single string, or again
-    # nil if EOF occurs before any data is received.  Note that
-    # received data includes the matched sequence we were looking for.
-    #
-    # +options+ can be either a regular expression or a hash of options.
-    # If a regular expression, this specifies the data to wait for.
-    # If a hash, this can specify the following options:
-    #
-    # Match:: a regular expression, specifying the data to wait for.
-    # Prompt:: as for Match; used only if Match is not specified.
-    # String:: as for Match, except a string that will be converted
-    #          into a regular expression.  Used only if Match and
-    #          Prompt are not specified.
-    # Timeout:: the number of seconds to wait for data from the host
-    #           before raising a TimeoutError.  If set to false,
-    #           no timeout will occur.  If not specified, the
-    #           Timeout option value specified when this instance
-    #           was created will be used, or, failing that, the
-    #           default value of 10 seconds.
-    # Waittime:: the number of seconds to wait after matching against
-    #            the input data to see if more data arrives.  If more
-    #            data arrives within this time, we will judge ourselves
-    #            not to have matched successfully, and will continue
-    #            trying to match.  If not specified, the Waittime option
-    #            value specified when this instance was created will be
-    #            used, or, failing that, the default value of 0 seconds,
-    #            which means not to wait for more input.
-    # FailEOF:: if true, when the remote end closes the connection then an
-    #           EOFError will be raised. Otherwise, defaults to the old
-    #           behaviour that the function will return whatever data
-    #           has been received already, or nil if nothing was received.
-    #
-    def waitfor(options) # :yield: recvdata
-      time_out = @options["Timeout"]
-      waittime = @options["Waittime"]
-      fail_eof = @options["FailEOF"]
-
-      if options.kind_of?(Hash)
-        prompt   = if options.has_key?("Match")
-                     options["Match"]
-                   elsif options.has_key?("Prompt")
-                     options["Prompt"]
-                   elsif options.has_key?("String")
-                     Regexp.new( Regexp.quote(options["String"]) )
-                   end
-        time_out = options["Timeout"]  if options.has_key?("Timeout")
-        waittime = options["Waittime"] if options.has_key?("Waittime")
-        fail_eof = options["FailEOF"]  if options.has_key?("FailEOF")
-      else
-        prompt = options
-      end
-
-      if time_out == false
-        time_out = nil
-      end
-
-      line = ''
-      buf = ''
-      rest = ''
-      until(prompt === line and not IO::select([@sock], nil, nil, waittime))
-        unless IO::select([@sock], nil, nil, time_out)
-          raise TimeoutError, "timed out while waiting for more data"
-        end
-        begin
-          c = @sock.readpartial(1024 * 1024)
-          @dumplog.log_dump('<', c) if @options.has_key?("Dump_log")
-          if @options["Telnetmode"]
-            c = rest + c
-            if Integer(c.rindex(/#{IAC}#{SE}/no) || 0) <
-               Integer(c.rindex(/#{IAC}#{SB}/no) || 0)
-              buf = preprocess(c[0 ... c.rindex(/#{IAC}#{SB}/no)])
-              rest = c[c.rindex(/#{IAC}#{SB}/no) .. -1]
-            elsif pt = c.rindex(/#{IAC}[^#{IAC}#{AO}#{AYT}#{DM}#{IP}#{NOP}]?\z/no) ||
-                       c.rindex(/\r\z/no)
-              buf = preprocess(c[0 ... pt])
-              rest = c[pt .. -1]
-            else
-              buf = preprocess(c)
-              rest = ''
-            end
-         else
-           # Not Telnetmode.
-           #
-           # We cannot use preprocess() on this data, because that
-           # method makes some Telnetmode-specific assumptions.
-           buf = rest + c
-           rest = ''
-           unless @options["Binmode"]
-             if pt = buf.rindex(/\r\z/no)
-               buf = buf[0 ... pt]
-               rest = buf[pt .. -1]
-             end
-             buf.gsub!(/#{EOL}/no, "\n")
-           end
-          end
-          @log.print(buf) if @options.has_key?("Output_log")
-          line += buf
-          yield buf if block_given?
-        rescue EOFError # End of file reached
-          raise if fail_eof
-          if line == ''
-            line = nil
-            yield nil if block_given?
-          end
-          break
-        end
-      end
-      line
-    end
-
-    # Write +string+ to the host.
-    #
-    # Does not perform any conversions on +string+.  Will log +string+ to the
-    # dumplog, if the Dump_log option is set.
-    def write(string)
-      length = string.length
-      while 0 < length
-        IO::select(nil, [@sock])
-        @dumplog.log_dump('>', string[-length..-1]) if @options.has_key?("Dump_log")
-        length -= @sock.syswrite(string[-length..-1])
-      end
-    end
-
-    # Sends a string to the host.
-    #
-    # This does _not_ automatically append a newline to the string.  Embedded
-    # newlines may be converted and telnet command sequences escaped
-    # depending upon the values of telnetmode, binmode, and telnet options
-    # set by the host.
-    def print(string)
-      string = string.gsub(/#{IAC}/no, IAC + IAC) if @options["Telnetmode"]
-
-      if @options["Binmode"]
-        self.write(string)
-      else
-        if @telnet_option["BINARY"] and @telnet_option["SGA"]
-          # IAC WILL SGA IAC DO BIN send EOL --> CR
-          self.write(string.gsub(/\n/n, CR))
-        elsif @telnet_option["SGA"]
-          # IAC WILL SGA send EOL --> CR+NULL
-          self.write(string.gsub(/\n/n, CR + NULL))
-        else
-          # NONE send EOL --> CR+LF
-          self.write(string.gsub(/\n/n, EOL))
-        end
-      end
-    end
-
-    # Sends a string to the host.
-    #
-    # Same as #print(), but appends a newline to the string.
-    def puts(string)
-      self.print(string + "\n")
-    end
-
-    # Send a command to the host.
-    #
-    # More exactly, sends a string to the host, and reads in all received
-    # data until is sees the prompt or other matched sequence.
-    #
-    # If a block is given, the received data will be yielded to it as
-    # it is read in.  Whether a block is given or not, the received data
-    # will be return as a string.  Note that the received data includes
-    # the prompt and in most cases the host's echo of our command.
-    #
-    # +options+ is either a String, specified the string or command to
-    # send to the host; or it is a hash of options.  If a hash, the
-    # following options can be specified:
-    #
-    # String:: the command or other string to send to the host.
-    # Match:: a regular expression, the sequence to look for in
-    #         the received data before returning.  If not specified,
-    #         the Prompt option value specified when this instance
-    #         was created will be used, or, failing that, the default
-    #         prompt of /[$%#>] \z/n.
-    # Timeout:: the seconds to wait for data from the host before raising
-    #           a Timeout error.  If not specified, the Timeout option
-    #           value specified when this instance was created will be
-    #           used, or, failing that, the default value of 10 seconds.
-    #
-    # The command or other string will have the newline sequence appended
-    # to it.
-    def cmd(options) # :yield: recvdata
-      match    = @options["Prompt"]
-      time_out = @options["Timeout"]
-      fail_eof = @options["FailEOF"]
-
-      if options.kind_of?(Hash)
-        string   = options["String"]
-        match    = options["Match"]   if options.has_key?("Match")
-        time_out = options["Timeout"] if options.has_key?("Timeout")
-        fail_eof = options["FailEOF"] if options.has_key?("FailEOF")
-      else
-        string = options
-      end
-
-      self.puts(string)
-      if block_given?
-        waitfor({"Prompt" => match, "Timeout" => time_out, "FailEOF" => fail_eof}){|c| yield c }
-      else
-        waitfor({"Prompt" => match, "Timeout" => time_out, "FailEOF" => fail_eof})
-      end
-    end
-
-    # Login to the host with a given username and password.
-    #
-    # The username and password can either be provided as two string
-    # arguments in that order, or as a hash with keys "Name" and
-    # "Password".
-    #
-    # This method looks for the strings "login" and "Password" from the
-    # host to determine when to send the username and password.  If the
-    # login sequence does not follow this pattern (for instance, you
-    # are connecting to a service other than telnet), you will need
-    # to handle login yourself.
-    #
-    # The password can be omitted, either by only
-    # provided one String argument, which will be used as the username,
-    # or by providing a has that has no "Password" key.  In this case,
-    # the method will not look for the "Password:" prompt; if it is
-    # sent, it will have to be dealt with by later calls.
-    #
-    # The method returns all data received during the login process from
-    # the host, including the echoed username but not the password (which
-    # the host should not echo).  If a block is passed in, this received
-    # data is also yielded to the block as it is received.
-    def login(options, password = nil) # :yield: recvdata
-      login_prompt = /[Ll]ogin[: ]*\z/n
-      password_prompt = /[Pp]ass(?:word|phrase)[: ]*\z/n
-      if options.kind_of?(Hash)
-        username = options["Name"]
-        password = options["Password"]
-        login_prompt = options["LoginPrompt"] if options["LoginPrompt"]
-        password_prompt = options["PasswordPrompt"] if options["PasswordPrompt"]
-      else
-        username = options
-      end
-
-      if block_given?
-        line = waitfor(login_prompt){|c| yield c }
-        if password
-          line += cmd({"String" => username,
-                       "Match" => password_prompt}){|c| yield c }
-          line += cmd(password){|c| yield c }
-        else
-          line += cmd(username){|c| yield c }
-        end
-      else
-        line = waitfor(login_prompt)
-        if password
-          line += cmd({"String" => username,
-                       "Match" => password_prompt})
-          line += cmd(password)
-        else
-          line += cmd(username)
-        end
-      end
-      line
-    end
-
-    # Closes the connection
-    def close
-      @sock.close
-    end
-
-  end  # class Telnet
-end  # module Net
-
diff --git a/lib/observer.rb b/lib/observer.rb
deleted file mode 100644
index a5d0dc0f4e..0000000000
--- a/lib/observer.rb
+++ /dev/null
@@ -1,202 +0,0 @@
-#
-# Implementation of the _Observer_ object-oriented design pattern.  The
-# following documentation is copied, with modifications, from "Programming
-# Ruby", by Hunt and Thomas; http://www.rubycentral.com/book/lib_patterns.html.
-#
-# See Observable for more info.
-
-# The Observer pattern (also known as publish/subscribe) provides a simple
-# mechanism for one object to inform a set of interested third-party objects
-# when its state changes.
-#
-# == Mechanism
-#
-# The notifying class mixes in the +Observable+
-# module, which provides the methods for managing the associated observer
-# objects.
-#
-# The observers must implement a method called +update+ to receive
-# notifications.
-#
-# The observable object must:
-# * assert that it has +#changed+
-# * call +#notify_observers+
-#
-# === Example
-#
-# The following example demonstrates this nicely.  A +Ticker+, when run,
-# continually receives the stock +Price+ for its <tt>@symbol</tt>.  A +Warner+
-# is a general observer of the price, and two warners are demonstrated, a
-# +WarnLow+ and a +WarnHigh+, which print a warning if the price is below or
-# above their set limits, respectively.
-#
-# The +update+ callback allows the warners to run without being explicitly
-# called.  The system is set up with the +Ticker+ and several observers, and the
-# observers do their duty without the top-level code having to interfere.
-#
-# Note that the contract between publisher and subscriber (observable and
-# observer) is not declared or enforced.  The +Ticker+ publishes a time and a
-# price, and the warners receive that.  But if you don't ensure that your
-# contracts are correct, nothing else can warn you.
-#
-#   require "observer"
-#
-#   class Ticker          ### Periodically fetch a stock price.
-#     include Observable
-#
-#     def initialize(symbol)
-#       @symbol = symbol
-#     end
-#
-#     def run
-#       lastPrice = nil
-#       loop do
-#         price = Price.fetch(@symbol)
-#         print "Current price: #{price}\n"
-#         if price != lastPrice
-#           changed                 # notify observers
-#           lastPrice = price
-#           notify_observers(Time.now, price)
-#         end
-#         sleep 1
-#       end
-#     end
-#   end
-#
-#   class Price           ### A mock class to fetch a stock price (60 - 140).
-#     def Price.fetch(symbol)
-#       60 + rand(80)
-#     end
-#   end
-#
-#   class Warner          ### An abstract observer of Ticker objects.
-#     def initialize(ticker, limit)
-#       @limit = limit
-#       ticker.add_observer(self)
-#     end
-#   end
-#
-#   class WarnLow < Warner
-#     def update(time, price)       # callback for observer
-#       if price < @limit
-#         print "--- #{time.to_s}: Price below #@limit: #{price}\n"
-#       end
-#     end
-#   end
-#
-#   class WarnHigh < Warner
-#     def update(time, price)       # callback for observer
-#       if price > @limit
-#         print "+++ #{time.to_s}: Price above #@limit: #{price}\n"
-#       end
-#     end
-#   end
-#
-#   ticker = Ticker.new("MSFT")
-#   WarnLow.new(ticker, 80)
-#   WarnHigh.new(ticker, 120)
-#   ticker.run
-#
-# Produces:
-#
-#   Current price: 83
-#   Current price: 75
-#   --- Sun Jun 09 00:10:25 CDT 2002: Price below 80: 75
-#   Current price: 90
-#   Current price: 134
-#   +++ Sun Jun 09 00:10:25 CDT 2002: Price above 120: 134
-#   Current price: 134
-#   Current price: 112
-#   Current price: 79
-#   --- Sun Jun 09 00:10:25 CDT 2002: Price below 80: 79
-module Observable
-
-  #
-  # Add +observer+ as an observer on this object. so that it will receive
-  # notifications.
-  #
-  # +observer+:: the object that will be notified of changes.
-  # +func+:: Symbol naming the method that will be called when this Observable
-  #          has changes.
-  #
-  #          This method must return true for +observer.respond_to?+ and will
-  #          receive <tt>*arg</tt> when #notify_observers is called, where
-  #          <tt>*arg</tt> is the value passed to #notify_observers by this
-  #          Observable
-  def add_observer(observer, func=:update)
-    @observer_peers = {} unless defined? @observer_peers
-    unless observer.respond_to? func
-      raise NoMethodError, "observer does not respond to `#{func.to_s}'"
-    end
-    @observer_peers[observer] = func
-  end
-
-  #
-  # Remove +observer+ as an observer on this object so that it will no longer
-  # receive notifications.
-  #
-  # +observer+:: An observer of this Observable
-  def delete_observer(observer)
-    @observer_peers.delete observer if defined? @observer_peers
-  end
-
-  #
-  # Remove all observers associated with this object.
-  #
-  def delete_observers
-    @observer_peers.clear if defined? @observer_peers
-  end
-
-  #
-  # Return the number of observers associated with this object.
-  #
-  def count_observers
-    if defined? @observer_peers
-      @observer_peers.size
-    else
-      0
-    end
-  end
-
-  #
-  # Set the changed state of this object.  Notifications will be sent only if
-  # the changed +state+ is +true+.
-  #
-  # +state+:: Boolean indicating the changed state of this Observable.
-  #
-  def changed(state=true)
-    @observer_state = state
-  end
-
-  #
-  # Returns true if this object's state has been changed since the last
-  # #notify_observers call.
-  #
-  def changed?
-    if defined? @observer_state and @observer_state
-      true
-    else
-      false
-    end
-  end
-
-  #
-  # Notify observers of a change in state *if* this object's changed state is
-  # +true+.
-  #
-  # This will invoke the method named in #add_observer, pasing <tt>*arg</tt>.
-  # The changed state is then set to +false+.
-  #
-  # <tt>*arg</tt>:: Any arguments to pass to the observers.
-  def notify_observers(*arg)
-    if defined? @observer_state and @observer_state
-      if defined? @observer_peers
-        @observer_peers.each do |k, v|
-          k.send v, *arg
-        end
-      end
-      @observer_state = false
-    end
-  end
-
-end
diff --git a/lib/open-uri.gemspec b/lib/open-uri.gemspec
new file mode 100644
index 0000000000..b6aaf35200
--- /dev/null
+++ b/lib/open-uri.gemspec
@@ -0,0 +1,32 @@
+name = File.basename(__FILE__, ".gemspec")
+version = ["lib", "."].find do |dir|
+  break File.foreach(File.join(__dir__, dir, "#{name}.rb")) do |line|
+    /^\s*VERSION\s*=\s*"(.*)"/ =~ line and break $1
+  end rescue nil
+end
+
+Gem::Specification.new do |spec|
+  spec.name          = name
+  spec.version       = version
+  spec.authors       = ["Tanaka Akira"]
+  spec.email         = ["akr@fsij.org"]
+
+  spec.summary       = %q{An easy-to-use wrapper for Net::HTTP, Net::HTTPS and Net::FTP.}
+  spec.description   = %q{An easy-to-use wrapper for Net::HTTP, Net::HTTPS and Net::FTP.}
+  spec.homepage      = "https://github.com/ruby/open-uri"
+  spec.required_ruby_version = Gem::Requirement.new(">= 2.3.0")
+  spec.licenses      = ["Ruby", "BSD-2-Clause"]
+
+  spec.metadata["homepage_uri"] = spec.homepage
+  spec.metadata["source_code_uri"] = spec.homepage
+
+  spec.files         = Dir.chdir(File.expand_path('..', __FILE__)) do
+    `git ls-files -z`.split("\x0").reject { |f| f.match(%r{\A((bin|test|spec|features)/|\.git|[Rr]ake|Gemfile)|\.gemspec\z}) }
+  end
+  spec.executables   = []
+  spec.require_paths = ["lib"]
+
+  spec.add_dependency "uri"
+  spec.add_dependency "stringio"
+  spec.add_dependency "time"
+end
diff --git a/lib/open-uri.rb b/lib/open-uri.rb
index 6e24b40ba5..844865b13a 100644
--- a/lib/open-uri.rb
+++ b/lib/open-uri.rb
@@ -1,30 +1,29 @@
+# frozen_string_literal: true
 require 'uri'
 require 'stringio'
 require 'time'
 
-module Kernel
-  private
-  alias open_uri_original_open open # :nodoc:
-  class << self
-    alias open_uri_original_open open # :nodoc:
-  end
-
-  # Allows the opening of various resources including URIs.
+module URI
+  # Allows the opening of various resources including URIs. Example:
   #
-  # If the first argument responds to the 'open' method, 'open' is called on
+  #   require "open-uri"
+  #   URI.open("http://example.com") { |f| f.read }
+  #
+  # If the first argument responds to the +open+ method, +open+ is called on
   # it with the rest of the arguments.
   #
-  # If the first argument is a string that begins with xxx://, it is parsed by
-  # URI.parse.  If the parsed object responds to the 'open' method,
-  # 'open' is called on it with the rest of the arguments.
+  # If the first argument is a string that begins with <code>(protocol)://</code>, it is parsed by
+  # URI.parse.  If the parsed object responds to the +open+ method,
+  # +open+ is called on it with the rest of the arguments.
+  #
+  # Otherwise, Kernel#open is called.
   #
-  # Otherwise, the original Kernel#open is called.
+  # OpenURI::OpenRead#open provides URI::HTTP#open, URI::HTTPS#open and
+  # URI::FTP#open, Kernel#open.
   #
-  # Since open-uri.rb provides URI::HTTP#open, URI::HTTPS#open and
-  # URI::FTP#open, Kernel[#.]open can accept URIs and strings that begin with
-  # http://, https:// and ftp://.  In these cases, the opened file object is
-  # extended by OpenURI::Meta.
-  def open(name, *rest, &block) # :doc:
+  # We can accept URIs and strings that begin with <code>http://</code>, <code>https://</code> and
+  # <code>ftp://</code>. In these cases, the opened file object is extended by OpenURI::Meta.
+  def self.open(name, *rest, &block)
     if name.respond_to?(:open)
       name.open(*rest, &block)
     elsif name.respond_to?(:to_str) &&
@@ -32,26 +31,26 @@ module Kernel
           (uri = URI.parse(name)).respond_to?(:open)
       uri.open(*rest, &block)
     else
-      open_uri_original_open(name, *rest, &block)
+      super
     end
   end
-  module_function :open
+  singleton_class.send(:ruby2_keywords, :open) if respond_to?(:ruby2_keywords, true)
 end
 
-# OpenURI is an easy-to-use wrapper for net/http, net/https and net/ftp.
+# OpenURI is an easy-to-use wrapper for Net::HTTP, Net::HTTPS and Net::FTP.
 #
-#== Example
+# == Example
 #
 # It is possible to open an http, https or ftp URL as though it were a file:
 #
-#   open("http://www.ruby-lang.org/") {|f|
+#   URI.open("http://www.ruby-lang.org/") {|f|
 #     f.each_line {|line| p line}
 #   }
 #
 # The opened file has several getter methods for its meta-information, as
 # follows, since it is extended by OpenURI::Meta.
 #
-#   open("http://www.ruby-lang.org/en") {|f|
+#   URI.open("http://www.ruby-lang.org/en") {|f|
 #     f.each_line {|line| p line}
 #     p f.base_uri         # <URI::HTTP:0x40e6ef2 URL:http://www.ruby-lang.org/en/>
 #     p f.content_type     # "text/html"
@@ -62,7 +61,7 @@ end
 #
 # Additional header fields can be specified by an optional hash argument.
 #
-#   open("http://www.ruby-lang.org/en/",
+#   URI.open("http://www.ruby-lang.org/en/",
 #     "User-Agent" => "Ruby/#{RUBY_VERSION}",
 #     "From" => "foo@bar.invalid",
 #     "Referer" => "http://www.ruby-lang.org/") {|f|
@@ -70,12 +69,14 @@ end
 #   }
 #
 # The environment variables such as http_proxy, https_proxy and ftp_proxy
-# are in effect by default.  :proxy => nil disables proxy.
+# are in effect by default. Here we disable proxy:
 #
-#   open("http://www.ruby-lang.org/en/raa.html", :proxy => nil) {|f|
+#   URI.open("http://www.ruby-lang.org/en/", :proxy => nil) {|f|
 #     # ...
 #   }
 #
+# See OpenURI::OpenRead.open and URI.open for more on available options.
+#
 # URI objects can be opened in a similar way.
 #
 #   uri = URI.parse("http://www.ruby-lang.org/en/")
@@ -92,6 +93,11 @@ end
 # Author:: Tanaka Akira <akr@m17n.org>
 
 module OpenURI
+
+  # The version string
+  VERSION = "0.5.0"
+
+  # The default options
   Options = {
     :proxy => true,
     :proxy_http_basic_authentication => true,
@@ -99,10 +105,16 @@ module OpenURI
     :content_length_proc => true,
     :http_basic_authentication => true,
     :read_timeout => true,
+    :open_timeout => true,
     :ssl_ca_cert => nil,
     :ssl_verify_mode => nil,
+    :ssl_min_version => nil,
+    :ssl_max_version => nil,
     :ftp_active_mode => false,
     :redirect => true,
+    :encoding => nil,
+    :max_redirects => 64,
+    :request_specific_fields => nil,
   }
 
   def OpenURI.check_options(options) # :nodoc:
@@ -136,7 +148,17 @@ module OpenURI
       encoding, = $1,Encoding.find($1) if $1
       mode = nil
     end
-
+    if options.has_key? :encoding
+      if !encoding.nil?
+        raise ArgumentError, "encoding specified twice"
+      end
+      encoding = Encoding.find(options[:encoding])
+    end
+    if options.has_key? :request_specific_fields
+      if !(options[:request_specific_fields].is_a?(Hash) || options[:request_specific_fields].is_a?(Proc))
+        raise ArgumentError, "Invalid request_specific_fields option: #{options[:request_specific_fields].inspect}"
+      end
+    end
     unless mode == nil ||
            mode == 'r' || mode == 'rb' ||
            mode == File::RDONLY
@@ -149,7 +171,11 @@ module OpenURI
       begin
         yield io
       ensure
-        io.close
+        if io.respond_to? :close!
+          io.close! # Tempfile
+        else
+          io.close if !io.closed?
+        end
       end
     else
       io
@@ -196,11 +222,20 @@ module OpenURI
     end
 
     uri_set = {}
+    max_redirects = options[:max_redirects] || Options.fetch(:max_redirects)
     buf = nil
     while true
+      request_specific_fields = {}
+      if options.has_key? :request_specific_fields
+        request_specific_fields = if options[:request_specific_fields].is_a?(Hash)
+                                    options[:request_specific_fields]
+                                  else options[:request_specific_fields].is_a?(Proc)
+                                    options[:request_specific_fields].call(uri)
+                                  end
+      end
       redirect = catch(:open_uri_redirect) {
         buf = Buffer.new
-        uri.buffer_open(buf, find_proxy.call(uri), options)
+        uri.buffer_open(buf, find_proxy.call(uri), options.merge(request_specific_fields))
         nil
       }
       if redirect
@@ -220,9 +255,14 @@ module OpenURI
           options = options.dup
           options.delete :http_basic_authentication
         end
+        if options.include?(:request_specific_fields) && options[:request_specific_fields].is_a?(Hash)
+          # Send request specific headers only for the initial request.
+          options.delete :request_specific_fields
+        end
         uri = redirect
         raise "HTTP redirection loop: #{uri}" if uri_set.include? uri.to_s
         uri_set[uri.to_s] = true
+        raise TooManyRedirects.new("Too many redirects", buf.io) if max_redirects && uri_set.size > max_redirects
       else
         break
       end
@@ -240,7 +280,7 @@ module OpenURI
     # (RFC 2109 4.3.1, RFC 2965 3.3, RFC 2616 15.1.3)
     # However this is ad hoc.  It should be extensible/configurable.
     uri1.scheme.downcase == uri2.scheme.downcase ||
-    (/\A(?:http|ftp)\z/i =~ uri1.scheme && /\A(?:http|ftp)\z/i =~ uri2.scheme)
+    (/\A(?:http|ftp)\z/i =~ uri1.scheme && /\A(?:https?|ftp)\z/i =~ uri2.scheme)
   end
 
   def OpenURI.open_http(buf, target, proxy, options) # :nodoc:
@@ -249,8 +289,7 @@ module OpenURI
       raise "Non-HTTP proxy URI: #{proxy_uri}" if proxy_uri.class != URI::HTTP
     end
 
-    if target.userinfo && "1.9.0" <= RUBY_VERSION
-      # don't raise for 1.8 because compatibility.
+    if target.userinfo
       raise ArgumentError, "userinfo not supported.  [RFC3986]"
     end
 
@@ -262,6 +301,9 @@ module OpenURI
     if URI::HTTP === target
       # HTTP or HTTPS
       if proxy
+        unless proxy_user && proxy_pass
+          proxy_user, proxy_pass = proxy_uri.userinfo.split(':') if proxy_uri.userinfo
+        end
         if proxy_user && proxy_pass
           klass = Net::HTTP::Proxy(proxy_uri.hostname, proxy_uri.port, proxy_user, proxy_pass)
         else
@@ -277,21 +319,26 @@ module OpenURI
       target_port = proxy_uri.port
       request_uri = target.to_s
       if proxy_user && proxy_pass
-        header["Proxy-Authorization"] = 'Basic ' + ["#{proxy_user}:#{proxy_pass}"].pack('m').delete("\r\n")
+        header["Proxy-Authorization"] =
+                        'Basic ' + ["#{proxy_user}:#{proxy_pass}"].pack('m0')
       end
     end
 
-    http = klass.new(target_host, target_port)
+    http = proxy ? klass.new(target_host, target_port) : klass.new(target_host, target_port, nil)
     if target.class == URI::HTTPS
       require 'net/https'
       http.use_ssl = true
       http.verify_mode = options[:ssl_verify_mode] || OpenSSL::SSL::VERIFY_PEER
+      http.min_version = options[:ssl_min_version]
+      http.max_version = options[:ssl_max_version]
       store = OpenSSL::X509::Store.new
       if options[:ssl_ca_cert]
-        if File.directory? options[:ssl_ca_cert]
-          store.add_path options[:ssl_ca_cert]
-        else
-          store.add_file options[:ssl_ca_cert]
+        Array(options[:ssl_ca_cert]).each do |cert|
+          if File.directory? cert
+            store.add_path cert
+          else
+            store.add_file cert
+          end
         end
       else
         store.set_default_paths
@@ -301,6 +348,9 @@ module OpenURI
     if options.include? :read_timeout
       http.read_timeout = options[:read_timeout]
     end
+    if options.include? :open_timeout
+      http.open_timeout = options[:open_timeout]
+    end
 
     resp = nil
     http.start {
@@ -323,19 +373,21 @@ module OpenURI
           if options[:progress_proc] && Net::HTTPSuccess === resp
             options[:progress_proc].call(buf.size)
           end
+          str.clear
         }
       }
     }
     io = buf.io
     io.rewind
     io.status = [resp.code, resp.message]
-    resp.each {|name,value| buf.io.meta_add_field name, value }
+    resp.each_name {|name| buf.io.meta_add_field2 name, resp.get_fields(name) }
     case resp
     when Net::HTTPSuccess
     when Net::HTTPMovedPermanently, # 301
          Net::HTTPFound, # 302
          Net::HTTPSeeOther, # 303
-         Net::HTTPTemporaryRedirect # 307
+         Net::HTTPTemporaryRedirect, # 307
+         Net::HTTPPermanentRedirect # 308
       begin
         loc_uri = URI.parse(resp['location'])
       rescue URI::InvalidURIError
@@ -347,23 +399,32 @@ module OpenURI
     end
   end
 
+  # Raised on HTTP session failure
   class HTTPError < StandardError
-    def initialize(message, io)
+    def initialize(message, io) # :nodoc:
       super(message)
       @io = io
     end
+    # StringIO having the received data
     attr_reader :io
   end
 
+  # Raised on redirection,
+  # only occurs when +redirect+ option for HTTP is +false+.
   class HTTPRedirect < HTTPError
-    def initialize(message, io, uri)
+    def initialize(message, io, uri) # :nodoc:
       super(message, io)
       @uri = uri
     end
+    # URI to redirect
     attr_reader :uri
   end
 
-  class Buffer # :nodoc:
+  # Raised on too many redirection,
+  class TooManyRedirects < HTTPError
+  end
+
+  class Buffer # :nodoc: all
     def initialize
       @io = StringIO.new
       @size = 0
@@ -390,19 +451,27 @@ module OpenURI
     end
   end
 
+  # :stopdoc:
+  RE_LWS = /[\r\n\t ]+/n
+  RE_TOKEN = %r{[^\x00- ()<>@,;:\\"/\[\]?={}\x7f]+}n
+  RE_QUOTED_STRING = %r{"(?:[\r\n\t !#-\[\]-~\x80-\xff]|\\[\x00-\x7f])*"}n
+  RE_PARAMETERS = %r{(?:;#{RE_LWS}?#{RE_TOKEN}#{RE_LWS}?=#{RE_LWS}?(?:#{RE_TOKEN}|#{RE_QUOTED_STRING})#{RE_LWS}?)*}n
+  # :startdoc:
+
   # Mixin for holding meta-information.
   module Meta
     def Meta.init(obj, src=nil) # :nodoc:
       obj.extend Meta
       obj.instance_eval {
         @base_uri = nil
-        @meta = {}
+        @meta = {} # name to string.  legacy.
+        @metas = {} # name to array of strings.
       }
       if src
         obj.status = src.status
         obj.base_uri = src.base_uri
-        src.meta.each {|name, value|
-          obj.meta_add_field(name, value)
+        src.metas.each {|name, values|
+          obj.meta_add_field2(name, values)
         }
       end
     end
@@ -416,8 +485,16 @@ module OpenURI
 
     # returns a Hash that represents header fields.
     # The Hash keys are downcased for canonicalization.
+    # The Hash values are a field body.
+    # If there are multiple field with same field name,
+    # the field values are concatenated with a comma.
     attr_reader :meta
 
+    # returns a Hash that represents header fields.
+    # The Hash keys are downcased for canonicalization.
+    # The Hash value are an array of field values.
+    attr_reader :metas
+
     def meta_setup_encoding # :nodoc:
       charset = self.charset
       enc = nil
@@ -437,30 +514,31 @@ module OpenURI
       end
     end
 
-    def meta_add_field(name, value) # :nodoc:
+    def meta_add_field2(name, values) # :nodoc:
       name = name.downcase
-      @meta[name] = value
+      @metas[name] = values
+      @meta[name] = values.join(', ')
       meta_setup_encoding if name == 'content-type'
     end
 
+    def meta_add_field(name, value) # :nodoc:
+      meta_add_field2(name, [value])
+    end
+
     # returns a Time that represents the Last-Modified field.
     def last_modified
-      if v = @meta['last-modified']
+      if vs = @metas['last-modified']
+        v = vs.join(', ')
         Time.httpdate(v)
       else
         nil
       end
     end
 
-    RE_LWS = /[\r\n\t ]+/n
-    RE_TOKEN = %r{[^\x00- ()<>@,;:\\"/\[\]?={}\x7f]+}n
-    RE_QUOTED_STRING = %r{"(?:[\r\n\t !#-\[\]-~\x80-\xff]|\\[\x00-\x7f])*"}n
-    RE_PARAMETERS = %r{(?:;#{RE_LWS}?#{RE_TOKEN}#{RE_LWS}?=#{RE_LWS}?(?:#{RE_TOKEN}|#{RE_QUOTED_STRING})#{RE_LWS}?)*}n
-
     def content_type_parse # :nodoc:
-      v = @meta['content-type']
+      vs = @metas['content-type']
       # The last (?:;#{RE_LWS}?)? matches extra ";" which violates RFC2045.
-      if v && %r{\A#{RE_LWS}?(#{RE_TOKEN})#{RE_LWS}?/(#{RE_TOKEN})#{RE_LWS}?(#{RE_PARAMETERS})(?:;#{RE_LWS}?)?\z}no =~ v
+      if vs && %r{\A#{RE_LWS}?(#{RE_TOKEN})#{RE_LWS}?/(#{RE_TOKEN})#{RE_LWS}?(#{RE_PARAMETERS})(?:;#{RE_LWS}?)?\z}no =~ vs.join(', ')
         type = $1.downcase
         subtype = $2.downcase
         parameters = []
@@ -492,28 +570,28 @@ module OpenURI
     # It can be used to guess charset.
     #
     # If charset parameter and block is not given,
-    # nil is returned except text type in HTTP.
-    # In that case, "iso-8859-1" is returned as defined by RFC2616 3.7.1.
+    # nil is returned except text type.
+    # In that case, "utf-8" is returned as defined by RFC6838 4.2.1
     def charset
       type, *parameters = content_type_parse
       if pair = parameters.assoc('charset')
         pair.last.downcase
       elsif block_given?
         yield
-      elsif type && %r{\Atext/} =~ type &&
-            @base_uri && /\Ahttp\z/i =~ @base_uri.scheme
-        "iso-8859-1" # RFC2616 3.7.1
+      elsif type && %r{\Atext/} =~ type
+        "utf-8" # RFC6838 4.2.1
       else
         nil
       end
     end
 
-    # returns a list of encodings in Content-Encoding field
-    # as an Array of String.
+    # Returns a list of encodings in Content-Encoding field as an array of
+    # strings.
+    #
     # The encodings are downcased for canonicalization.
     def content_encoding
-      v = @meta['content-encoding']
-      if v && %r{\A#{RE_LWS}?#{RE_TOKEN}#{RE_LWS}?(?:,#{RE_LWS}?#{RE_TOKEN}#{RE_LWS}?)*}o =~ v
+      vs = @metas['content-encoding']
+      if vs && %r{\A#{RE_LWS}?#{RE_TOKEN}#{RE_LWS}?(?:,#{RE_LWS}?#{RE_TOKEN}#{RE_LWS}?)*}o =~ (v = vs.join(', '))
         v.scan(RE_TOKEN).map {|content_coding| content_coding.downcase}
       else
         []
@@ -601,8 +679,8 @@ module OpenURI
     #  is called before actual transfer is started.
     #  It takes one argument, which is expected content length in bytes.
     #
-    #  If two or more transfer is done by HTTP redirection, the procedure
-    #  is called only one for a last transfer.
+    #  If two or more transfers are performed by HTTP redirection, the
+    #  procedure is called only once for the last transfer.
     #
     #  When expected content length is unknown, the procedure is called with
     #  nil.  This happens when the HTTP response has no Content-Length header.
@@ -641,9 +719,16 @@ module OpenURI
     #
     #  :read_timeout option specifies a timeout of read for http connections.
     #
+    # [:open_timeout]
+    #  Synopsis:
+    #    :open_timeout=>nil     (no timeout)
+    #    :open_timeout=>10      (10 second)
+    #
+    #  :open_timeout option specifies a timeout of open for http connections.
+    #
     # [:ssl_ca_cert]
     #  Synopsis:
-    #    :ssl_ca_cert=>filename
+    #    :ssl_ca_cert=>filename or an Array of filenames
     #
     #  :ssl_ca_cert is used to specify CA certificate for SSL.
     #  If it is given, default certificates are not used.
@@ -654,6 +739,20 @@ module OpenURI
     #
     #  :ssl_verify_mode is used to specify openssl verify mode.
     #
+    # [:ssl_min_version]
+    #  Synopsis:
+    #    :ssl_min_version=>:TLS1_2
+    #
+    #  :ssl_min_version option specifies the minimum allowed SSL/TLS protocol
+    #  version.  See also OpenSSL::SSL::SSLContext#min_version=.
+    #
+    # [:ssl_max_version]
+    #  Synopsis:
+    #    :ssl_max_version=>:TLS1_2
+    #
+    #  :ssl_max_version option specifies the maximum allowed SSL/TLS protocol
+    #  version.  See also OpenSSL::SSL::SSLContext#max_version=.
+    #
     # [:ftp_active_mode]
     #  Synopsis:
     #    :ftp_active_mode=>bool
@@ -673,11 +772,49 @@ module OpenURI
     #  Using +true+ also means that redirections between http and ftp are
     #  permitted.
     #
+    # [:max_redirects]
+    #  Synopsis:
+    #    :max_redirects=>int
+    #
+    #  Number of HTTP redirects allowed before OpenURI::TooManyRedirects is raised.
+    #  The default is 64.
+    #
+    # [:request_specific_fields]
+    #  Synopsis:
+    #    :request_specific_fields => {}
+    #    :request_specific_fields => lambda {|url| ...}
+    #
+    #  :request_specific_fields option allows specifying custom header fields that
+    #  are sent with the HTTP request. It can be passed as a Hash or a Proc that
+    #  gets evaluated on each request and returns a Hash of header fields.
+    #
+    #  If a Hash is provided, it specifies the headers only for the initial
+    #  request and these headers will not be sent on redirects.
+    #
+    #  If a Proc is provided, it will be executed for each request including
+    #  redirects, allowing dynamic header customization based on the request URL.
+    #  It is important that the Proc returns a Hash. And this Hash specifies the
+    #  headers to be sent with the request.
+    #
+    #  For Example with Hash
+    #    URI.open("http://...",
+    #             request_specific_fields: {"Authorization" => "token dummy"}) {|f| ... }
+    #
+    #  For Example with Proc:
+    #    URI.open("http://...",
+    #             request_specific_fields: lambda { |uri|
+    #               if uri.host == "example.com"
+    #                 {"Authorization" => "token dummy"}
+    #               else
+    #                 {}
+    #               end
+    #             }) {|f| ... }
+    #
     def open(*rest, &block)
       OpenURI.open_uri(self, *rest, &block)
     end
 
-    # OpenURI::OpenRead#read([options]) reads a content referenced by self and
+    # OpenURI::OpenRead#read([ options ]) reads a content referenced by self and
     # returns the content as string.
     # The string is extended with OpenURI::Meta.
     # The argument +options+ is same as OpenURI::OpenRead#open.
@@ -692,84 +829,6 @@ module OpenURI
 end
 
 module URI
-  class Generic
-    # returns a proxy URI.
-    # The proxy URI is obtained from environment variables such as http_proxy,
-    # ftp_proxy, no_proxy, etc.
-    # If there is no proper proxy, nil is returned.
-    #
-    # Note that capitalized variables (HTTP_PROXY, FTP_PROXY, NO_PROXY, etc.)
-    # are examined too.
-    #
-    # But http_proxy and HTTP_PROXY is treated specially under CGI environment.
-    # It's because HTTP_PROXY may be set by Proxy: header.
-    # So HTTP_PROXY is not used.
-    # http_proxy is not used too if the variable is case insensitive.
-    # CGI_HTTP_PROXY can be used instead.
-    def find_proxy
-      name = self.scheme.downcase + '_proxy'
-      proxy_uri = nil
-      if name == 'http_proxy' && ENV.include?('REQUEST_METHOD') # CGI?
-        # HTTP_PROXY conflicts with *_proxy for proxy settings and
-        # HTTP_* for header information in CGI.
-        # So it should be careful to use it.
-        pairs = ENV.reject {|k, v| /\Ahttp_proxy\z/i !~ k }
-        case pairs.length
-        when 0 # no proxy setting anyway.
-          proxy_uri = nil
-        when 1
-          k, _ = pairs.shift
-          if k == 'http_proxy' && ENV[k.upcase] == nil
-            # http_proxy is safe to use because ENV is case sensitive.
-            proxy_uri = ENV[name]
-          else
-            proxy_uri = nil
-          end
-        else # http_proxy is safe to use because ENV is case sensitive.
-          proxy_uri = ENV.to_hash[name]
-        end
-        if !proxy_uri
-          # Use CGI_HTTP_PROXY.  cf. libwww-perl.
-          proxy_uri = ENV["CGI_#{name.upcase}"]
-        end
-      elsif name == 'http_proxy'
-        unless proxy_uri = ENV[name]
-          if proxy_uri = ENV[name.upcase]
-            warn 'The environment variable HTTP_PROXY is discouraged.  Use http_proxy.'
-          end
-        end
-      else
-        proxy_uri = ENV[name] || ENV[name.upcase]
-      end
-
-      if proxy_uri && self.hostname
-        require 'socket'
-        begin
-          addr = IPSocket.getaddress(self.hostname)
-          proxy_uri = nil if /\A127\.|\A::1\z/ =~ addr
-        rescue SocketError
-        end
-      end
-
-      if proxy_uri
-        proxy_uri = URI.parse(proxy_uri)
-        name = 'no_proxy'
-        if no_proxy = ENV[name] || ENV[name.upcase]
-          no_proxy.scan(/([^:,]*)(?::(\d+))?/) {|host, port|
-            if /(\A|\.)#{Regexp.quote host}\z/i =~ self.host &&
-               (!port || self.port == port.to_i)
-              proxy_uri = nil
-              break
-            end
-          }
-        end
-        proxy_uri
-      else
-        nil
-      end
-    end
-  end
-
   class HTTP
     def buffer_open(buf, proxy, options) # :nodoc:
       OpenURI.open_http(buf, self, proxy, options)
@@ -784,7 +843,12 @@ module URI
         OpenURI.open_http(buf, self, proxy, options)
         return
       end
-      require 'net/ftp'
+
+      begin
+        require 'net/ftp'
+      rescue LoadError
+        abort "net/ftp is not found. You may need to `gem install net-ftp` to install net/ftp."
+      end
 
       path = self.path
       path = path.sub(%r{\A/}, '%2F') # re-encode the beginning slash because uri library decodes it.
@@ -811,7 +875,7 @@ module URI
       # The access sequence is defined by RFC 1738
       ftp = Net::FTP.new
       ftp.connect(self.hostname, self.port)
-      ftp.passive = true if !options[:ftp_active_mode]
+      ftp.passive = !options[:ftp_active_mode]
       # todo: extract user/passwd from .netrc.
       user = 'anonymous'
       passwd = nil
diff --git a/lib/open3.rb b/lib/open3.rb
index 03a7937c09..74d00b86d9 100644
--- a/lib/open3.rb
+++ b/lib/open3.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 #
 # = open3.rb: Popen, but with stderr, too
 #
@@ -9,66 +11,209 @@
 #
 
 #
-# Open3 grants you access to stdin, stdout, stderr and a thread to wait the
+# Open3 grants you access to stdin, stdout, stderr and a thread to wait for the
 # child process when running another program.
 # You can specify various attributes, redirections, current directory, etc., of
-# the program as Process.spawn.
+# the program in the same way as for Process.spawn.
 #
 # - Open3.popen3 : pipes for stdin, stdout, stderr
 # - Open3.popen2 : pipes for stdin, stdout
 # - Open3.popen2e : pipes for stdin, merged stdout and stderr
-# - Open3.capture3 : give a string for stdin.  get strings for stdout, stderr
-# - Open3.capture2 : give a string for stdin.  get a string for stdout
-# - Open3.capture2e : give a string for stdin.  get a string for merged stdout and stderr
+# - Open3.capture3 : give a string for stdin; get strings for stdout, stderr
+# - Open3.capture2 : give a string for stdin; get a string for stdout
+# - Open3.capture2e : give a string for stdin; get a string for merged stdout and stderr
 # - Open3.pipeline_rw : pipes for first stdin and last stdout of a pipeline
 # - Open3.pipeline_r : pipe for last stdout of a pipeline
 # - Open3.pipeline_w : pipe for first stdin of a pipeline
-# - Open3.pipeline_start : a pipeline
-# - Open3.pipeline : run a pipline and wait
+# - Open3.pipeline_start : run a pipeline without waiting
+# - Open3.pipeline : run a pipeline and wait for its completion
 #
 
+require 'open3/version'
+
+# \Module \Open3 supports creating child processes
+# with access to their $stdin, $stdout, and $stderr streams.
+#
+# == What's Here
+#
+# Each of these methods executes a given command in a new process or subshell,
+# or multiple commands in new processes and/or subshells:
+#
+# - Each of these methods executes a single command in a process or subshell,
+#   accepts a string for input to $stdin,
+#   and returns string output from $stdout, $stderr, or both:
+#
+#   - Open3.capture2: Executes the command;
+#     returns the string from $stdout.
+#   - Open3.capture2e: Executes the command;
+#     returns the string from merged $stdout and $stderr.
+#   - Open3.capture3: Executes the command;
+#     returns strings from $stdout and $stderr.
+#
+# - Each of these methods executes a single command in a process or subshell,
+#   and returns pipes for $stdin, $stdout, and/or $stderr:
+#
+#   - Open3.popen2: Executes the command;
+#     returns pipes for $stdin and $stdout.
+#   - Open3.popen2e: Executes the command;
+#     returns pipes for $stdin and merged $stdout and $stderr.
+#   - Open3.popen3: Executes the command;
+#     returns pipes for $stdin, $stdout, and $stderr.
+#
+# - Each of these methods executes one or more commands in processes and/or subshells,
+#   returns pipes for the first $stdin, the last $stdout, or both:
+#
+#   - Open3.pipeline_r: Returns a pipe for the last $stdout.
+#   - Open3.pipeline_rw: Returns pipes for the first $stdin and the last $stdout.
+#   - Open3.pipeline_w: Returns a pipe for the first $stdin.
+#   - Open3.pipeline_start: Does not wait for processes to complete.
+#   - Open3.pipeline: Waits for processes to complete.
+#
+# Each of the methods above accepts:
+#
+# - An optional hash of environment variable names and values;
+#   see {Execution Environment}[rdoc-ref:Process@Execution+Environment].
+# - A required string argument that is a +command_line+ or +exe_path+;
+#   see {Argument command_line or exe_path}[rdoc-ref:Process@Argument+command_line+or+exe_path].
+# - An optional hash of execution options;
+#   see {Execution Options}[rdoc-ref:Process@Execution+Options].
+#
 module Open3
 
-  # Open stdin, stdout, and stderr streams and start external executable.
-  # In addition, a thread for waiting the started process is noticed.
-  # The thread has a pid method and thread variable :pid which is the pid of
-  # the started process.
+  # :call-seq:
+  #   Open3.popen3([env, ] command_line, options = {}) -> [stdin, stdout, stderr, wait_thread]
+  #   Open3.popen3([env, ] exe_path, *args, options = {}) -> [stdin, stdout, stderr, wait_thread]
+  #   Open3.popen3([env, ] command_line, options = {}) {|stdin, stdout, stderr, wait_thread| ... } -> object
+  #   Open3.popen3([env, ] exe_path, *args, options = {}) {|stdin, stdout, stderr, wait_thread| ... } -> object
+  #
+  # Basically a wrapper for
+  # {Process.spawn}[rdoc-ref:Process.spawn]
+  # that:
+  #
+  # - Creates a child process, by calling Process.spawn with the given arguments.
+  # - Creates streams +stdin+, +stdout+, and +stderr+,
+  #   which are the standard input, standard output, and standard error streams
+  #   in the child process.
+  # - Creates thread +wait_thread+ that waits for the child process to exit;
+  #   the thread has method +pid+, which returns the process ID
+  #   of the child process.
+  #
+  # With no block given, returns the array
+  # <tt>[stdin, stdout, stderr, wait_thread]</tt>.
+  # The caller should close each of the three returned streams.
+  #
+  #   stdin, stdout, stderr, wait_thread = Open3.popen3('echo')
+  #   # => [#<IO:fd 8>, #<IO:fd 10>, #<IO:fd 12>, #<Process::Waiter:0x00007f58d5428f58 run>]
+  #   stdin.close
+  #   stdout.close
+  #   stderr.close
+  #   wait_thread.pid   # => 2210481
+  #   wait_thread.value # => #<Process::Status: pid 2210481 exit 0>
+  #
+  # With a block given, calls the block with the four variables
+  # (three streams and the wait thread)
+  # and returns the block's return value.
+  # The caller need not close the streams:
+  #
+  #   Open3.popen3('echo') do |stdin, stdout, stderr, wait_thread|
+  #     p stdin
+  #     p stdout
+  #     p stderr
+  #     p wait_thread
+  #     p wait_thread.pid
+  #     p wait_thread.value
+  #   end
   #
-  # Block form:
+  # Output:
   #
-  #   Open3.popen3([env,] cmd... [, opts]) {|stdin, stdout, stderr, wait_thr|
-  #     pid = wait_thr.pid # pid of the started process.
-  #     ...
-  #     exit_status = wait_thr.value # Process::Status object returned.
-  #   }
+  #   #<IO:fd 6>
+  #   #<IO:fd 7>
+  #   #<IO:fd 9>
+  #   #<Process::Waiter:0x00007f58d53606e8 sleep>
+  #   2211047
+  #   #<Process::Status: pid 2211047 exit 0>
   #
-  # Non-block form:
+  # Like Process.spawn, this method has potential security vulnerabilities
+  # if called with untrusted input;
+  # see {Command Injection}[rdoc-ref:command_injection.rdoc@Command+Injection].
   #
-  #   stdin, stdout, stderr, wait_thr = Open3.popen3([env,] cmd... [, opts])
-  #   pid = wait_thr[:pid]  # pid of the started process.
-  #   ...
-  #   stdin.close  # stdin, stdout and stderr should be closed explicitly in this form.
-  #   stdout.close
-  #   stderr.close
-  #   exit_status = wait_thr.value  # Process::Status object returned.
+  # Unlike Process.spawn, this method waits for the child process to exit
+  # before returning, so the caller need not do so.
+  #
+  # If the first argument is a hash, it becomes leading argument +env+
+  # in the call to Process.spawn;
+  # see {Execution Environment}[rdoc-ref:Process@Execution+Environment].
+  #
+  # If the last argument is a hash, it becomes trailing argument +options+
+  # in the call to Process.spawn;
+  # see {Execution Options}[rdoc-ref:Process@Execution+Options].
+  #
+  # The single required argument is one of the following:
+  #
+  # - +command_line+ if it is a string,
+  #   and if it begins with a shell reserved word or special built-in,
+  #   or if it contains one or more metacharacters.
+  # - +exe_path+ otherwise.
+  #
+  # <b>Argument +command_line+</b>
+  #
+  # \String argument +command_line+ is a command line to be passed to a shell;
+  # it must begin with a shell reserved word, begin with a special built-in,
+  # or contain meta characters:
+  #
+  #   Open3.popen3('if true; then echo "Foo"; fi') {|*args| p args } # Shell reserved word.
+  #   Open3.popen3('echo') {|*args| p args }                         # Built-in.
+  #   Open3.popen3('date > date.tmp') {|*args| p args }              # Contains meta character.
+  #
+  # Output (similar for each call above):
+  #
+  #   [#<IO:(closed)>, #<IO:(closed)>, #<IO:(closed)>, #<Process::Waiter:0x00007f58d52f28c8 dead>]
+  #
+  # The command line may also contain arguments and options for the command:
+  #
+  #   Open3.popen3('echo "Foo"') { |i, o, e, t| o.gets }
+  #   "Foo\n"
   #
-  # The parameters +cmd...+ is passed to Process.spawn.
-  # So a commandline string and list of argument strings can be accepted as follows.
+  # <b>Argument +exe_path+</b>
   #
-  #   Open3.popen3("echo a") {|i, o, e, t| ... }
-  #   Open3.popen3("echo", "a") {|i, o, e, t| ... }
-  #   Open3.popen3(["echo", "argv0"], "a") {|i, o, e, t| ... }
+  # Argument +exe_path+ is one of the following:
   #
-  # If the last parameter, opts, is a Hash, it is recognized as an option for Process.spawn.
+  # - The string path to an executable to be called.
+  # - A 2-element array containing the path to an executable
+  #   and the string to be used as the name of the executing process.
   #
-  #   Open3.popen3("pwd", :chdir=>"/") {|i,o,e,t|
-  #     p o.read.chomp #=> "/"
-  #   }
+  # Example:
+  #
+  #   Open3.popen3('/usr/bin/date') { |i, o, e, t| o.gets }
+  #   # => "Wed Sep 27 02:56:44 PM CDT 2023\n"
+  #
+  # Ruby invokes the executable directly, with no shell and no shell expansion:
+  #
+  #   Open3.popen3('doesnt_exist') { |i, o, e, t| o.gets } # Raises Errno::ENOENT
   #
-  # wait_thr.value waits the termination of the process.
-  # The block form also waits the process when it returns.
+  # If one or more +args+ is given, each is an argument or option
+  # to be passed to the executable:
   #
-  # Closing stdin, stdout and stderr does not wait the process.
+  #   Open3.popen3('echo', 'C #') { |i, o, e, t| o.gets }
+  #   # => "C #\n"
+  #   Open3.popen3('echo', 'hello', 'world') { |i, o, e, t| o.gets }
+  #   # => "hello world\n"
+  #
+  # Take care to avoid deadlocks.
+  # Output streams +stdout+ and +stderr+ have fixed-size buffers,
+  # so reading extensively from one but not the other can cause a deadlock
+  # when the unread buffer fills.
+  # To avoid that, +stdout+ and +stderr+ should be read simultaneously
+  # (using threads or IO.select).
+  #
+  # Related:
+  #
+  # - Open3.popen2: Makes the standard input and standard output streams
+  #   of the child process available as separate streams,
+  #   with no access to the standard error stream.
+  # - Open3.popen2e: Makes the standard input and the merge
+  #   of the standard output and standard error streams
+  #   of the child process available as separate streams.
   #
   def popen3(*cmd, &block)
     if Hash === cmd.last
@@ -91,45 +236,131 @@ module Open3
   end
   module_function :popen3
 
-  # Open3.popen2 is similer to Open3.popen3 except it doesn't make a pipe for
-  # the standard error stream.
+  # :call-seq:
+  #   Open3.popen2([env, ] command_line, options = {}) -> [stdin, stdout, wait_thread]
+  #   Open3.popen2([env, ] exe_path, *args, options = {}) -> [stdin, stdout, wait_thread]
+  #   Open3.popen2([env, ] command_line, options = {}) {|stdin, stdout, wait_thread| ... } -> object
+  #   Open3.popen2([env, ] exe_path, *args, options = {}) {|stdin, stdout, wait_thread| ... } -> object
+  #
+  # Basically a wrapper for
+  # {Process.spawn}[rdoc-ref:Process.spawn]
+  # that:
+  #
+  # - Creates a child process, by calling Process.spawn with the given arguments.
+  # - Creates streams +stdin+ and +stdout+,
+  #   which are the standard input and standard output streams
+  #   in the child process.
+  # - Creates thread +wait_thread+ that waits for the child process to exit;
+  #   the thread has method +pid+, which returns the process ID
+  #   of the child process.
+  #
+  # With no block given, returns the array
+  # <tt>[stdin, stdout, wait_thread]</tt>.
+  # The caller should close each of the two returned streams.
+  #
+  #   stdin, stdout, wait_thread = Open3.popen2('echo')
+  #   # => [#<IO:fd 6>, #<IO:fd 7>, #<Process::Waiter:0x00007f58d52dbe98 run>]
+  #   stdin.close
+  #   stdout.close
+  #   wait_thread.pid   # => 2263572
+  #   wait_thread.value # => #<Process::Status: pid 2263572 exit 0>
+  #
+  # With a block given, calls the block with the three variables
+  # (two streams and the wait thread)
+  # and returns the block's return value.
+  # The caller need not close the streams:
+  #
+  #   Open3.popen2('echo') do |stdin, stdout, wait_thread|
+  #     p stdin
+  #     p stdout
+  #     p wait_thread
+  #     p wait_thread.pid
+  #     p wait_thread.value
+  #   end
   #
-  # Block form:
+  # Output:
   #
-  #   Open3.popen2([env,] cmd... [, opts]) {|stdin, stdout, wait_thr|
-  #     pid = wait_thr.pid # pid of the started process.
-  #     ...
-  #     exit_status = wait_thr.value # Process::Status object returned.
-  #   }
+  #   #<IO:fd 6>
+  #   #<IO:fd 7>
+  #   #<Process::Waiter:0x00007f58d59a34b0 sleep>
+  #   2263636
+  #   #<Process::Status: pid 2263636 exit 0>
   #
-  # Non-block form:
+  # Like Process.spawn, this method has potential security vulnerabilities
+  # if called with untrusted input;
+  # see {Command Injection}[rdoc-ref:command_injection.rdoc@Command+Injection].
   #
-  #   stdin, stdout, wait_thr = Open3.popen2([env,] cmd... [, opts])
-  #   ...
-  #   stdin.close  # stdin and stdout should be closed explicitly in this form.
-  #   stdout.close
+  # Unlike Process.spawn, this method waits for the child process to exit
+  # before returning, so the caller need not do so.
+  #
+  # If the first argument is a hash, it becomes leading argument +env+
+  # in the call to Process.spawn;
+  # see {Execution Environment}[rdoc-ref:Process@Execution+Environment].
+  #
+  # If the last argument is a hash, it becomes trailing argument +options+
+  # in the call to Process.spawn;
+  # see {Execution Options}[rdoc-ref:Process@Execution+Options].
+  #
+  # The single required argument is one of the following:
+  #
+  # - +command_line+ if it is a string,
+  #   and if it begins with a shell reserved word or special built-in,
+  #   or if it contains one or more metacharacters.
+  # - +exe_path+ otherwise.
+  #
+  # <b>Argument +command_line+</b>
   #
-  # See Process.spawn for the optional hash arguments _env_ and _opts_.
+  # \String argument +command_line+ is a command line to be passed to a shell;
+  # it must begin with a shell reserved word, begin with a special built-in,
+  # or contain meta characters:
+  #
+  #   Open3.popen2('if true; then echo "Foo"; fi') {|*args| p args } # Shell reserved word.
+  #   Open3.popen2('echo') {|*args| p args }                         # Built-in.
+  #   Open3.popen2('date > date.tmp') {|*args| p args }              # Contains meta character.
+  #
+  # Output (similar for each call above):
+  #
+  #   # => [#<IO:(closed)>, #<IO:(closed)>, #<Process::Waiter:0x00007f7577dfe410 dead>]
+  #
+  # The command line may also contain arguments and options for the command:
+  #
+  #   Open3.popen2('echo "Foo"') { |i, o, t| o.gets }
+  #   "Foo\n"
+  #
+  # <b>Argument +exe_path+</b>
+  #
+  # Argument +exe_path+ is one of the following:
+  #
+  # - The string path to an executable to be called.
+  # - A 2-element array containing the path to an executable
+  #   and the string to be used as the name of the executing process.
   #
   # Example:
   #
-  #   Open3.popen2("wc -c") {|i,o,t|
-  #     i.print "answer to life the universe and everything"
-  #     i.close
-  #     p o.gets #=> "42\n"
-  #   }
+  #   Open3.popen2('/usr/bin/date') { |i, o, t| o.gets }
+  #   # => "Thu Sep 28 09:41:06 AM CDT 2023\n"
+  #
+  # Ruby invokes the executable directly, with no shell and no shell expansion:
+  #
+  #   Open3.popen2('doesnt_exist') { |i, o, t| o.gets } # Raises Errno::ENOENT
+  #
+  # If one or more +args+ is given, each is an argument or option
+  # to be passed to the executable:
   #
-  #   Open3.popen2("bc -q") {|i,o,t|
-  #     i.puts "obase=13"
-  #     i.puts "6 * 9"
-  #     p o.gets #=> "42\n"
-  #   }
+  #   Open3.popen2('echo', 'C #') { |i, o, t| o.gets }
+  #   # => "C #\n"
+  #   Open3.popen2('echo', 'hello', 'world') { |i, o, t| o.gets }
+  #   # => "hello world\n"
   #
-  #   Open3.popen2("dc") {|i,o,t|
-  #     i.print "42P"
-  #     i.close
-  #     p o.read #=> "*"
-  #   }
+  #
+  # Related:
+  #
+  # - Open3.popen2e: Makes the standard input and the merge
+  #   of the standard output and standard error streams
+  #   of the child process available as separate streams.
+  # - Open3.popen3: Makes the standard input, standard output,
+  #   and standard error streams
+  #   of the child process available as separate streams.
   #
   def popen2(*cmd, &block)
     if Hash === cmd.last
@@ -149,36 +380,130 @@ module Open3
   end
   module_function :popen2
 
-  # Open3.popen2e is similer to Open3.popen3 except it merges
-  # the standard output stream and the standard error stream.
+  # :call-seq:
+  #   Open3.popen2e([env, ] command_line, options = {}) -> [stdin, stdout_and_stderr, wait_thread]
+  #   Open3.popen2e([env, ] exe_path, *args, options = {}) -> [stdin, stdout_and_stderr, wait_thread]
+  #   Open3.popen2e([env, ] command_line, options = {}) {|stdin, stdout_and_stderr, wait_thread| ... } -> object
+  #   Open3.popen2e([env, ] exe_path, *args, options = {}) {|stdin, stdout_and_stderr, wait_thread| ... } -> object
+  #
+  # Basically a wrapper for
+  # {Process.spawn}[rdoc-ref:Process.spawn]
+  # that:
+  #
+  # - Creates a child process, by calling Process.spawn with the given arguments.
+  # - Creates streams +stdin+, +stdout_and_stderr+,
+  #   which are the standard input and the merge of the standard output
+  #   and standard error streams in the child process.
+  # - Creates thread +wait_thread+ that waits for the child process to exit;
+  #   the thread has method +pid+, which returns the process ID
+  #   of the child process.
+  #
+  # With no block given, returns the array
+  # <tt>[stdin, stdout_and_stderr, wait_thread]</tt>.
+  # The caller should close each of the two returned streams.
+  #
+  #   stdin, stdout_and_stderr, wait_thread = Open3.popen2e('echo')
+  #   # => [#<IO:fd 6>, #<IO:fd 7>, #<Process::Waiter:0x00007f7577da4398 run>]
+  #   stdin.close
+  #   stdout_and_stderr.close
+  #   wait_thread.pid   # => 2274600
+  #   wait_thread.value # => #<Process::Status: pid 2274600 exit 0>
+  #
+  # With a block given, calls the block with the three variables
+  # (two streams and the wait thread)
+  # and returns the block's return value.
+  # The caller need not close the streams:
+  #
+  #   Open3.popen2e('echo') do |stdin, stdout_and_stderr, wait_thread|
+  #     p stdin
+  #     p stdout_and_stderr
+  #     p wait_thread
+  #     p wait_thread.pid
+  #     p wait_thread.value
+  #   end
   #
-  # Block form:
+  # Output:
   #
-  #   Open3.popen2e([env,] cmd... [, opts]) {|stdin, stdout_and_stderr, wait_thr|
-  #     pid = wait_thr.pid # pid of the started process.
-  #     ...
-  #     exit_status = wait_thr.value # Process::Status object returned.
-  #   }
+  #   #<IO:fd 6>
+  #   #<IO:fd 7>
+  #   #<Process::Waiter:0x00007f75777578c8 sleep>
+  #   2274763
+  #   #<Process::Status: pid 2274763 exit 0>
   #
-  # Non-block form:
+  # Like Process.spawn, this method has potential security vulnerabilities
+  # if called with untrusted input;
+  # see {Command Injection}[rdoc-ref:command_injection.rdoc@Command+Injection].
   #
-  #   stdin, stdout_and_stderr, wait_thr = Open3.popen2e([env,] cmd... [, opts])
-  #   ...
-  #   stdin.close  # stdin and stdout_and_stderr should be closed explicitly in this form.
-  #   stdout_and_stderr.close
+  # Unlike Process.spawn, this method waits for the child process to exit
+  # before returning, so the caller need not do so.
+  #
+  # If the first argument is a hash, it becomes leading argument +env+
+  # in the call to Process.spawn;
+  # see {Execution Environment}[rdoc-ref:Process@Execution+Environment].
+  #
+  # If the last argument is a hash, it becomes trailing argument +options+
+  # in the call to Process.spawn;
+  # see {Execution Options}[rdoc-ref:Process@Execution+Options].
+  #
+  # The single required argument is one of the following:
+  #
+  # - +command_line+ if it is a string,
+  #   and if it begins with a shell reserved word or special built-in,
+  #   or if it contains one or more metacharacters.
+  # - +exe_path+ otherwise.
+  #
+  # <b>Argument +command_line+</b>
+  #
+  # \String argument +command_line+ is a command line to be passed to a shell;
+  # it must begin with a shell reserved word, begin with a special built-in,
+  # or contain meta characters:
+  #
+  #   Open3.popen2e('if true; then echo "Foo"; fi') {|*args| p args } # Shell reserved word.
+  #   Open3.popen2e('echo') {|*args| p args }                         # Built-in.
+  #   Open3.popen2e('date > date.tmp') {|*args| p args }              # Contains meta character.
+  #
+  # Output (similar for each call above):
+  #
+  #   # => [#<IO:(closed)>, #<IO:(closed)>, #<Process::Waiter:0x00007f7577d8a1f0 dead>]
+  #
+  # The command line may also contain arguments and options for the command:
+  #
+  #   Open3.popen2e('echo "Foo"') { |i, o_and_e, t| o_and_e.gets }
+  #   "Foo\n"
+  #
+  # <b>Argument +exe_path+</b>
+  #
+  # Argument +exe_path+ is one of the following:
   #
-  # See Process.spawn for the optional hash arguments _env_ and _opts_.
+  # - The string path to an executable to be called.
+  # - A 2-element array containing the path to an executable
+  #   and the string to be used as the name of the executing process.
   #
   # Example:
-  #   # check gcc warnings
-  #   source = "foo.c"
-  #   Open3.popen2e("gcc", "-Wall", source) {|i,oe,t|
-  #     oe.each {|line|
-  #       if /warning/ =~ line
-  #         ...
-  #       end
-  #     }
-  #   }
+  #
+  #   Open3.popen2e('/usr/bin/date') { |i, o_and_e, t| o_and_e.gets }
+  #   # => "Thu Sep 28 01:58:45 PM CDT 2023\n"
+  #
+  # Ruby invokes the executable directly, with no shell and no shell expansion:
+  #
+  #   Open3.popen2e('doesnt_exist') { |i, o_and_e, t| o_and_e.gets } # Raises Errno::ENOENT
+  #
+  # If one or more +args+ is given, each is an argument or option
+  # to be passed to the executable:
+  #
+  #   Open3.popen2e('echo', 'C #') { |i, o_and_e, t| o_and_e.gets }
+  #   # => "C #\n"
+  #   Open3.popen2e('echo', 'hello', 'world') { |i, o_and_e, t| o_and_e.gets }
+  #   # => "hello world\n"
+  #
+  # Related:
+  #
+  # - Open3.popen2: Makes the standard input and standard output streams
+  #   of the child process available as separate streams,
+  #   with no access to the standard error stream.
+  # - Open3.popen3: Makes the standard input, standard output,
+  #   and standard error streams
+  #   of the child process available as separate streams.
   #
   def popen2e(*cmd, &block)
     if Hash === cmd.last
@@ -195,19 +520,26 @@ module Open3
     opts[[:out, :err]] = out_w
 
     popen_run(cmd, opts, [in_r, out_w], [in_w, out_r], &block)
+  ensure
+    if block
+      in_r.close
+      in_w.close
+      out_r.close
+      out_w.close
+    end
   end
   module_function :popen2e
 
   def popen_run(cmd, opts, child_io, parent_io) # :nodoc:
     pid = spawn(*cmd, opts)
     wait_thr = Process.detach(pid)
-    child_io.each {|io| io.close }
+    child_io.each(&:close)
     result = [*parent_io, wait_thr]
     if defined? yield
       begin
         return yield(*result)
       ensure
-        parent_io.each{|io| io.close unless io.closed?}
+        parent_io.each(&:close)
         wait_thr.join
       end
     end
@@ -218,46 +550,102 @@ module Open3
     private :popen_run
   end
 
-  # Open3.capture3 captures the standard output and the standard error of a command.
+  # :call-seq:
+  #   Open3.capture3([env, ] command_line, options = {}) -> [stdout_s, stderr_s, status]
+  #   Open3.capture3([env, ] exe_path, *args, options = {}) -> [stdout_s, stderr_s, status]
+  #
+  # Basically a wrapper for Open3.popen3 that:
+  #
+  # - Creates a child process, by calling Open3.popen3 with the given arguments
+  #   (except for certain entries in hash +options+; see below).
+  # - Returns as strings +stdout_s+ and +stderr_s+ the standard output
+  #   and standard error of the child process.
+  # - Returns as +status+ a <tt>Process::Status</tt> object
+  #   that represents the exit status of the child process.
+  #
+  # Returns the array <tt>[stdout_s, stderr_s, status]</tt>:
+  #
+  #   stdout_s, stderr_s, status = Open3.capture3('echo "Foo"')
+  #   # => ["Foo\n", "", #<Process::Status: pid 2281954 exit 0>]
+  #
+  # Like Process.spawn, this method has potential security vulnerabilities
+  # if called with untrusted input;
+  # see {Command Injection}[rdoc-ref:command_injection.rdoc@Command+Injection].
   #
-  #   stdout_str, stderr_str, status = Open3.capture3([env,] cmd... [, opts])
+  # Unlike Process.spawn, this method waits for the child process to exit
+  # before returning, so the caller need not do so.
   #
-  # The arguments env, cmd and opts are passed to Open3.popen3 except
-  # opts[:stdin_data] and opts[:binmode].  See Process.spawn.
+  # If the first argument is a hash, it becomes leading argument +env+
+  # in the call to Open3.popen3;
+  # see {Execution Environment}[rdoc-ref:Process@Execution+Environment].
   #
-  # If opts[:stdin_data] is specified, it is sent to the command's standard input.
+  # If the last argument is a hash, it becomes trailing argument +options+
+  # in the call to Open3.popen3;
+  # see {Execution Options}[rdoc-ref:Process@Execution+Options].
   #
-  # If opts[:binmode] is true, internal pipes are set to binary mode.
+  # The hash +options+ is given;
+  # two options have local effect in method Open3.capture3:
+  #
+  # - If entry <tt>options[:stdin_data]</tt> exists, the entry is removed
+  #   and its string value is sent to the command's standard input:
+  #
+  #     Open3.capture3('tee', stdin_data: 'Foo')
+  #     # => ["Foo", "", #<Process::Status: pid 2319575 exit 0>]
+  #
+  # - If entry <tt>options[:binmode]</tt> exists, the entry is removed and
+  #   the internal streams are set to binary mode.
+  #
+  # The single required argument is one of the following:
+  #
+  # - +command_line+ if it is a string,
+  #   and if it begins with a shell reserved word or special built-in,
+  #   or if it contains one or more metacharacters.
+  # - +exe_path+ otherwise.
+  #
+  # <b>Argument +command_line+</b>
+  #
+  # \String argument +command_line+ is a command line to be passed to a shell;
+  # it must begin with a shell reserved word, begin with a special built-in,
+  # or contain meta characters:
+  #
+  #   Open3.capture3('if true; then echo "Foo"; fi') # Shell reserved word.
+  #   # => ["Foo\n", "", #<Process::Status: pid 2282025 exit 0>]
+  #   Open3.capture3('echo')                         # Built-in.
+  #   # => ["\n", "", #<Process::Status: pid 2282092 exit 0>]
+  #   Open3.capture3('date > date.tmp')              # Contains meta character.
+  #   # => ["", "", #<Process::Status: pid 2282110 exit 0>]
+  #
+  # The command line may also contain arguments and options for the command:
+  #
+  #   Open3.capture3('echo "Foo"')
+  #   # => ["Foo\n", "", #<Process::Status: pid 2282092 exit 0>]
+  #
+  # <b>Argument +exe_path+</b>
+  #
+  # Argument +exe_path+ is one of the following:
+  #
+  # - The string path to an executable to be called.
+  # - A 2-element array containing the path to an executable
+  #   and the string to be used as the name of the executing process.
   #
   # Example:
   #
-  #   # dot is a command of graphviz.
-  #   graph = <<'End'
-  #     digraph g {
-  #       a -> b
-  #     }
-  #   End
-  #   layouted_graph, dot_log = Open3.capture3("dot -v", :stdin_data=>graph)
-  #
-  #   o, e, s = Open3.capture3("echo a; sort >&2", :stdin_data=>"foo\nbar\nbaz\n")
-  #   p o #=> "a\n"
-  #   p e #=> "bar\nbaz\nfoo\n"
-  #   p s #=> #<Process::Status: pid 32682 exit 0>
-  #
-  #   # generate a thumnail image using the convert command of ImageMagick.
-  #   # However, if the image stored really in a file,
-  #   # system("convert", "-thumbnail", "80", "png:#{filename}", "png:-") is better
-  #   # because memory consumption.
-  #   # But if the image is stored in a DB or generated by gnuplot Open3.capture2 example,
-  #   # Open3.capture3 is considerable.
-  #   #
-  #   image = File.read("/usr/share/openclipart/png/animals/mammals/sheep-md-v0.1.png", :binmode=>true)
-  #   thumnail, err, s = Open3.capture3("convert -thumbnail 80 png:- png:-", :stdin_data=>image, :binmode=>true)
-  #   if s.success?
-  #     STDOUT.binmode; print thumnail
-  #   end
+  #   Open3.capture3('/usr/bin/date')
+  #   # => ["Thu Sep 28 05:03:51 PM CDT 2023\n", "", #<Process::Status: pid 2282300 exit 0>]
+  #
+  # Ruby invokes the executable directly, with no shell and no shell expansion:
   #
-  def capture3(*cmd, &block)
+  #   Open3.capture3('doesnt_exist') # Raises Errno::ENOENT
+  #
+  # If one or more +args+ is given, each is an argument or option
+  # to be passed to the executable:
+  #
+  #   Open3.capture3('echo', 'C #')
+  #   # => ["C #\n", "", #<Process::Status: pid 2282368 exit 0>]
+  #   Open3.capture3('echo', 'hello', 'world')
+  #   # => ["hello world\n", "", #<Process::Status: pid 2282372 exit 0>]
+  #
+  def capture3(*cmd)
     if Hash === cmd.last
       opts = cmd.pop.dup
     else
@@ -275,50 +663,123 @@ module Open3
       end
       out_reader = Thread.new { o.read }
       err_reader = Thread.new { e.read }
-      i.write stdin_data
+      begin
+        if stdin_data.respond_to? :readpartial
+          IO.copy_stream(stdin_data, i)
+        else
+          i.write stdin_data
+        end
+      rescue Errno::EPIPE
+      end
       i.close
       [out_reader.value, err_reader.value, t.value]
     }
   end
   module_function :capture3
 
-  # Open3.capture2 captures the standard output of a command.
+  # :call-seq:
+  #   Open3.capture2([env, ] command_line, options = {}) -> [stdout_s, status]
+  #   Open3.capture2([env, ] exe_path, *args, options = {}) -> [stdout_s, status]
+  #
+  # Basically a wrapper for Open3.popen3 that:
+  #
+  # - Creates a child process, by calling Open3.popen3 with the given arguments
+  #   (except for certain entries in hash +options+; see below).
+  # - Returns as string +stdout_s+ the standard output of the child process.
+  # - Returns as +status+ a <tt>Process::Status</tt> object
+  #   that represents the exit status of the child process.
+  #
+  # Returns the array <tt>[stdout_s, status]</tt>:
+  #
+  #   stdout_s, status = Open3.capture2('echo "Foo"')
+  #   # => ["Foo\n", #<Process::Status: pid 2326047 exit 0>]
+  #
+  # Like Process.spawn, this method has potential security vulnerabilities
+  # if called with untrusted input;
+  # see {Command Injection}[rdoc-ref:command_injection.rdoc@Command+Injection].
+  #
+  # Unlike Process.spawn, this method waits for the child process to exit
+  # before returning, so the caller need not do so.
+  #
+  # If the first argument is a hash, it becomes leading argument +env+
+  # in the call to Open3.popen3;
+  # see {Execution Environment}[rdoc-ref:Process@Execution+Environment].
+  #
+  # If the last argument is a hash, it becomes trailing argument +options+
+  # in the call to Open3.popen3;
+  # see {Execution Options}[rdoc-ref:Process@Execution+Options].
   #
-  #   stdout_str, status = Open3.capture2([env,] cmd... [, opts])
+  # The hash +options+ is given;
+  # two options have local effect in method Open3.capture2:
   #
-  # The arguments env, cmd and opts are passed to Open3.popen3 except
-  # opts[:stdin_data] and opts[:binmode].  See Process.spawn.
+  # - If entry <tt>options[:stdin_data]</tt> exists, the entry is removed
+  #   and its string value is sent to the command's standard input:
   #
-  # If opts[:stdin_data] is specified, it is sent to the command's standard input.
+  #     Open3.capture2('tee', stdin_data: 'Foo')
   #
-  # If opts[:binmode] is true, internal pipes are set to binary mode.
+  #     # => ["Foo", #<Process::Status: pid 2326087 exit 0>]
+  #
+  # - If entry <tt>options[:binmode]</tt> exists, the entry is removed and
+  #   the internal streams are set to binary mode.
+  #
+  # The single required argument is one of the following:
+  #
+  # - +command_line+ if it is a string,
+  #   and if it begins with a shell reserved word or special built-in,
+  #   or if it contains one or more metacharacters.
+  # - +exe_path+ otherwise.
+  #
+  # <b>Argument +command_line+</b>
+  #
+  # \String argument +command_line+ is a command line to be passed to a shell;
+  # it must begin with a shell reserved word, begin with a special built-in,
+  # or contain meta characters:
+  #
+  #   Open3.capture2('if true; then echo "Foo"; fi') # Shell reserved word.
+  #   # => ["Foo\n", #<Process::Status: pid 2326131 exit 0>]
+  #   Open3.capture2('echo')                         # Built-in.
+  #   # => ["\n", #<Process::Status: pid 2326139 exit 0>]
+  #   Open3.capture2('date > date.tmp')              # Contains meta character.
+  #   # => ["", #<Process::Status: pid 2326174 exit 0>]
+  #
+  # The command line may also contain arguments and options for the command:
+  #
+  #   Open3.capture2('echo "Foo"')
+  #   # => ["Foo\n", #<Process::Status: pid 2326183 exit 0>]
+  #
+  # <b>Argument +exe_path+</b>
+  #
+  # Argument +exe_path+ is one of the following:
+  #
+  # - The string path to an executable to be called.
+  # - A 2-element array containing the path to an executable
+  #   and the string to be used as the name of the executing process.
   #
   # Example:
   #
-  #   # factor is a command for integer factorization.
-  #   o, s = Open3.capture2("factor", :stdin_data=>"42")
-  #   p o #=> "42: 2 3 7\n"
-  #
-  #   # generate x**2 graph in png using gnuplot.
-  #   gnuplot_commands = <<"End"
-  #     set terminal png
-  #     plot x**2, "-" with lines
-  #     1 14
-  #     2 1
-  #     3 8
-  #     4 5
-  #     e
-  #   End
-  #   image, s = Open3.capture2("gnuplot", :stdin_data=>gnuplot_commands, :binmode=>true)
-  #
-  def capture2(*cmd, &block)
+  #   Open3.capture2('/usr/bin/date')
+  #   # => ["Fri Sep 29 01:00:39 PM CDT 2023\n", #<Process::Status: pid 2326222 exit 0>]
+  #
+  # Ruby invokes the executable directly, with no shell and no shell expansion:
+  #
+  #   Open3.capture2('doesnt_exist') # Raises Errno::ENOENT
+  #
+  # If one or more +args+ is given, each is an argument or option
+  # to be passed to the executable:
+  #
+  #   Open3.capture2('echo', 'C #')
+  #   # => ["C #\n", #<Process::Status: pid 2326267 exit 0>]
+  #   Open3.capture2('echo', 'hello', 'world')
+  #   # => ["hello world\n", #<Process::Status: pid 2326299 exit 0>]
+  #
+  def capture2(*cmd)
     if Hash === cmd.last
       opts = cmd.pop.dup
     else
       opts = {}
     end
 
-    stdin_data = opts.delete(:stdin_data) || ''
+    stdin_data = opts.delete(:stdin_data)
     binmode = opts.delete(:binmode)
 
     popen2(*cmd, opts) {|i, o, t|
@@ -327,37 +788,125 @@ module Open3
         o.binmode
       end
       out_reader = Thread.new { o.read }
-      i.write stdin_data
+      if stdin_data
+        begin
+          if stdin_data.respond_to? :readpartial
+            IO.copy_stream(stdin_data, i)
+          else
+            i.write stdin_data
+          end
+        rescue Errno::EPIPE
+        end
+      end
       i.close
       [out_reader.value, t.value]
     }
   end
   module_function :capture2
 
-  # Open3.capture2e captures the standard output and the standard error of a command.
+  # :call-seq:
+  #   Open3.capture2e([env, ] command_line, options = {}) -> [stdout_and_stderr_s, status]
+  #   Open3.capture2e([env, ] exe_path, *args, options = {}) -> [stdout_and_stderr_s, status]
+  #
+  # Basically a wrapper for Open3.popen3 that:
+  #
+  # - Creates a child process, by calling Open3.popen3 with the given arguments
+  #   (except for certain entries in hash +options+; see below).
+  # - Returns as string +stdout_and_stderr_s+ the merged standard output
+  #   and standard error of the child process.
+  # - Returns as +status+ a <tt>Process::Status</tt> object
+  #   that represents the exit status of the child process.
+  #
+  # Returns the array <tt>[stdout_and_stderr_s, status]</tt>:
+  #
+  #   stdout_and_stderr_s, status = Open3.capture2e('echo "Foo"')
+  #   # => ["Foo\n", #<Process::Status: pid 2371692 exit 0>]
+  #
+  # Like Process.spawn, this method has potential security vulnerabilities
+  # if called with untrusted input;
+  # see {Command Injection}[rdoc-ref:command_injection.rdoc@Command+Injection].
+  #
+  # Unlike Process.spawn, this method waits for the child process to exit
+  # before returning, so the caller need not do so.
+  #
+  # If the first argument is a hash, it becomes leading argument +env+
+  # in the call to Open3.popen3;
+  # see {Execution Environment}[rdoc-ref:Process@Execution+Environment].
+  #
+  # If the last argument is a hash, it becomes trailing argument +options+
+  # in the call to Open3.popen3;
+  # see {Execution Options}[rdoc-ref:Process@Execution+Options].
+  #
+  # The hash +options+ is given;
+  # two options have local effect in method Open3.capture2e:
   #
-  #   stdout_and_stderr_str, status = Open3.capture2e([env,] cmd... [, opts])
+  # - If entry <tt>options[:stdin_data]</tt> exists, the entry is removed
+  #   and its string value is sent to the command's standard input:
   #
-  # The arguments env, cmd and opts are passed to Open3.popen3 except
-  # opts[:stdin_data] and opts[:binmode].  See Process.spawn.
+  #     Open3.capture2e('tee', stdin_data: 'Foo')
+  #     # => ["Foo", #<Process::Status: pid 2371732 exit 0>]
   #
-  # If opts[:stdin_data] is specified, it is sent to the command's standard input.
+  # - If entry <tt>options[:binmode]</tt> exists, the entry is removed and
+  #   the internal streams are set to binary mode.
   #
-  # If opts[:binmode] is true, internal pipes are set to binary mode.
+  # The single required argument is one of the following:
+  #
+  # - +command_line+ if it is a string,
+  #   and if it begins with a shell reserved word or special built-in,
+  #   or if it contains one or more metacharacters.
+  # - +exe_path+ otherwise.
+  #
+  # <b>Argument +command_line+</b>
+  #
+  # \String argument +command_line+ is a command line to be passed to a shell;
+  # it must begin with a shell reserved word, begin with a special built-in,
+  # or contain meta characters:
+  #
+  #   Open3.capture2e('if true; then echo "Foo"; fi') # Shell reserved word.
+  #   # => ["Foo\n", #<Process::Status: pid 2371740 exit 0>]
+  #   Open3.capture2e('echo')                         # Built-in.
+  #   # => ["\n", #<Process::Status: pid 2371774 exit 0>]
+  #   Open3.capture2e('date > date.tmp')              # Contains meta character.
+  #   # => ["", #<Process::Status: pid 2371812 exit 0>]
+  #
+  # The command line may also contain arguments and options for the command:
+  #
+  #   Open3.capture2e('echo "Foo"')
+  #   # => ["Foo\n", #<Process::Status: pid 2326183 exit 0>]
+  #
+  # <b>Argument +exe_path+</b>
+  #
+  # Argument +exe_path+ is one of the following:
+  #
+  # - The string path to an executable to be called.
+  # - A 2-element array containing the path to an executable
+  #   and the string to be used as the name of the executing process.
   #
   # Example:
   #
-  #   # capture make log
-  #   make_log, s = Open3.capture2e("make")
+  #   Open3.capture2e('/usr/bin/date')
+  #   # => ["Sat Sep 30 09:01:46 AM CDT 2023\n", #<Process::Status: pid 2371820 exit 0>]
+  #
+  # Ruby invokes the executable directly, with no shell and no shell expansion:
+  #
+  #   Open3.capture2e('doesnt_exist') # Raises Errno::ENOENT
+  #
+  # If one or more +args+ is given, each is an argument or option
+  # to be passed to the executable:
   #
-  def capture2e(*cmd, &block)
+  #   Open3.capture2e('echo', 'C #')
+  #   # => ["C #\n", #<Process::Status: pid 2371856 exit 0>]
+  #   Open3.capture2e('echo', 'hello', 'world')
+  #   # => ["hello world\n", #<Process::Status: pid 2371894 exit 0>]
+  #
+  def capture2e(*cmd)
     if Hash === cmd.last
       opts = cmd.pop.dup
     else
       opts = {}
     end
 
-    stdin_data = opts.delete(:stdin_data) || ''
+    stdin_data = opts.delete(:stdin_data)
     binmode = opts.delete(:binmode)
 
     popen2e(*cmd, opts) {|i, oe, t|
@@ -366,55 +915,102 @@ module Open3
         oe.binmode
       end
       outerr_reader = Thread.new { oe.read }
-      i.write stdin_data
+      if stdin_data
+        begin
+          if stdin_data.respond_to? :readpartial
+            IO.copy_stream(stdin_data, i)
+          else
+            i.write stdin_data
+          end
+        rescue Errno::EPIPE
+        end
+      end
       i.close
       [outerr_reader.value, t.value]
     }
   end
   module_function :capture2e
 
-  # Open3.pipeline_rw starts a list of commands as a pipeline with pipes
-  # which connects stdin of the first command and stdout of the last command.
+  # :call-seq:
+  #   Open3.pipeline_rw([env, ] *cmds, options = {}) -> [first_stdin, last_stdout, wait_threads]
   #
-  #   Open3.pipeline_rw(cmd1, cmd2, ... [, opts]) {|first_stdin, last_stdout, wait_threads|
-  #     ...
-  #   }
+  # Basically a wrapper for
+  # {Process.spawn}[rdoc-ref:Process.spawn]
+  # that:
   #
-  #   first_stdin, last_stdout, wait_threads = Open3.pipeline_rw(cmd1, cmd2, ... [, opts])
-  #   ...
-  #   first_stdin.close
-  #   last_stdout.close
+  # - Creates a child process for each of the given +cmds+
+  #   by calling Process.spawn.
+  # - Pipes the +stdout+ from each child to the +stdin+ of the next child,
+  #   or, for the first child, from the caller's +stdin+,
+  #   or, for the last child, to the caller's +stdout+.
   #
-  # Each cmd is a string or an array.
-  # If it is an array, the elements are passed to Process.spawn.
+  # The method does not wait for child processes to exit,
+  # so the caller must do so.
   #
-  #   cmd:
-  #     commandline                              command line string which is passed to a shell
-  #     [env, commandline, opts]                 command line string which is passed to a shell
-  #     [env, cmdname, arg1, ..., opts]          command name and one or more arguments (no shell)
-  #     [env, [cmdname, argv0], arg1, ..., opts] command name and arguments including argv[0] (no shell)
+  # With no block given, returns a 3-element array containing:
   #
-  #   Note that env and opts are optional, as Process.spawn.
-  #
-  # The option to pass Process.spawn is constructed by merging
-  # +opts+, the last hash element of the array and
-  # specification for the pipe between each commands.
+  # - The +stdin+ stream of the first child process.
+  # - The +stdout+ stream of the last child process.
+  # - An array of the wait threads for all of the child processes.
   #
   # Example:
   #
-  #   Open3.pipeline_rw("tr -dc A-Za-z", "wc -c") {|i,o,ts|
-  #     i.puts "All persons more than a mile high to leave the court."
-  #     i.close
-  #     p o.gets #=> "42\n"
-  #   }
-  #
-  #   Open3.pipeline_rw("sort", "cat -n") {|stdin, stdout, wait_thrs|
-  #     stdin.puts "foo"
-  #     stdin.puts "bar"
-  #     stdin.puts "baz"
-  #     stdin.close     # send EOF to sort.
-  #     p stdout.read   #=> "     1\tbar\n     2\tbaz\n     3\tfoo\n"
-  #   }
+  #   first_stdin, last_stdout, wait_threads = Open3.pipeline_rw('sort', 'cat -n')
+  #   # => [#<IO:fd 20>, #<IO:fd 21>, [#<Process::Waiter:0x000055e8de29ab40 sleep>, #<Process::Waiter:0x000055e8de29a690 sleep>]]
+  #   first_stdin.puts("foo\nbar\nbaz")
+  #   first_stdin.close # Send EOF to sort.
+  #   puts last_stdout.read
+  #   wait_threads.each do |wait_thread|
+  #     wait_thread.join
+  #   end
+  #
+  # Output:
+  #
+  #   1	bar
+  #   2	baz
+  #   3	foo
+  #
+  # With a block given, calls the block with the +stdin+ stream of the first child,
+  # the +stdout+ stream  of the last child,
+  # and an array of the wait processes:
+  #
+  #   Open3.pipeline_rw('sort', 'cat -n') do |first_stdin, last_stdout, wait_threads|
+  #     first_stdin.puts "foo\nbar\nbaz"
+  #     first_stdin.close # send EOF to sort.
+  #     puts last_stdout.read
+  #     wait_threads.each do |wait_thread|
+  #       wait_thread.join
+  #     end
+  #   end
+  #
+  # Output:
+  #
+  #   1	bar
+  #   2	baz
+  #   3	foo
+  #
+  # Like Process.spawn, this method has potential security vulnerabilities
+  # if called with untrusted input;
+  # see {Command Injection}[rdoc-ref:command_injection.rdoc@Command+Injection].
+  #
+  # If the first argument is a hash, it becomes leading argument +env+
+  # in each call to Process.spawn;
+  # see {Execution Environment}[rdoc-ref:Process@Execution+Environment].
+  #
+  # If the last argument is a hash, it becomes trailing argument +options+
+  # in each call to Process.spawn;
+  # see {Execution Options}[rdoc-ref:Process@Execution+Options].
+  #
+  # Each remaining argument in +cmds+ is one of:
+  #
+  # - A +command_line+: a string that begins with a shell reserved word
+  #   or special built-in, or contains one or more metacharacters.
+  # - An +exe_path+: the string path to an executable to be called.
+  # - An array containing a +command_line+ or an +exe_path+,
+  #   along with zero or more string arguments for the command.
+  #
+  # See {Argument command_line or exe_path}[rdoc-ref:Process@Argument+command_line+or+exe_path].
+  #
   def pipeline_rw(*cmds, &block)
     if Hash === cmds.last
       opts = cmds.pop.dup
@@ -433,43 +1029,77 @@ module Open3
   end
   module_function :pipeline_rw
 
-  # Open3.pipeline_r starts a list of commands as a pipeline with a pipe
-  # which connects stdout of the last command.
+  # :call-seq:
+  #   Open3.pipeline_r([env, ] *cmds, options = {}) -> [last_stdout, wait_threads]
   #
-  #   Open3.pipeline_r(cmd1, cmd2, ... [, opts]) {|last_stdout, wait_threads|
-  #     ...
-  #   }
+  # Basically a wrapper for
+  # {Process.spawn}[rdoc-ref:Process.spawn]
+  # that:
   #
-  #   last_stdout, wait_threads = Open3.pipeline_r(cmd1, cmd2, ... [, opts])
-  #   ...
-  #   last_stdout.close
+  # - Creates a child process for each of the given +cmds+
+  #   by calling Process.spawn.
+  # - Pipes the +stdout+ from each child to the +stdin+ of the next child,
+  #   or, for the last child, to the caller's +stdout+.
   #
-  # Each cmd is a string or an array.
-  # If it is an array, the elements are passed to Process.spawn.
+  # The method does not wait for child processes to exit,
+  # so the caller must do so.
   #
-  #   cmd:
-  #     commandline                              command line string which is passed to a shell
-  #     [env, commandline, opts]                 command line string which is passed to a shell
-  #     [env, cmdname, arg1, ..., opts]          command name and one or more arguments (no shell)
-  #     [env, [cmdname, argv0], arg1, ..., opts] command name and arguments including argv[0] (no shell)
+  # With no block given, returns a 2-element array containing:
   #
-  #   Note that env and opts are optional, as Process.spawn.
+  # - The +stdout+ stream of the last child process.
+  # - An array of the wait threads for all of the child processes.
   #
   # Example:
   #
-  #   Open3.pipeline_r("zcat /var/log/apache2/access.log.*.gz",
-  #                    [{"LANG"=>"C"}, "grep", "GET /favicon.ico"],
-  #                    "logresolve") {|o, ts|
-  #     o.each_line {|line|
-  #       ...
-  #     }
-  #   }
+  #   last_stdout, wait_threads = Open3.pipeline_r('ls', 'grep R')
+  #   # => [#<IO:fd 5>, [#<Process::Waiter:0x000055e8de2f9898 dead>, #<Process::Waiter:0x000055e8de2f94b0 sleep>]]
+  #   puts last_stdout.read
+  #   wait_threads.each do |wait_thread|
+  #     wait_thread.join
+  #   end
+  #
+  # Output:
+  #
+  #   Rakefile
+  #   README.md
+  #
+  # With a block given, calls the block with the +stdout+ stream
+  # of the last child process,
+  # and an array of the wait processes:
+  #
+  #   Open3.pipeline_r('ls', 'grep R') do |last_stdout, wait_threads|
+  #     puts last_stdout.read
+  #     wait_threads.each do |wait_thread|
+  #       wait_thread.join
+  #     end
+  #   end
+  #
+  # Output:
+  #
+  #   Rakefile
+  #   README.md
+  #
+  # Like Process.spawn, this method has potential security vulnerabilities
+  # if called with untrusted input;
+  # see {Command Injection}[rdoc-ref:command_injection.rdoc@Command+Injection].
+  #
+  # If the first argument is a hash, it becomes leading argument +env+
+  # in each call to Process.spawn;
+  # see {Execution Environment}[rdoc-ref:Process@Execution+Environment].
+  #
+  # If the last argument is a hash, it becomes trailing argument +options+
+  # in each call to Process.spawn;
+  # see {Execution Options}[rdoc-ref:Process@Execution+Options].
   #
-  #   Open3.pipeline_r("yes", "head -10") {|o, ts|
-  #     p o.read      #=> "y\ny\ny\ny\ny\ny\ny\ny\ny\ny\n"
-  #     p ts[0].value #=> #<Process::Status: pid 24910 SIGPIPE (signal 13)>
-  #     p ts[1].value #=> #<Process::Status: pid 24913 exit 0>
-  #   }
+  # Each remaining argument in +cmds+ is one of:
+  #
+  # - A +command_line+: a string that begins with a shell reserved word
+  #   or special built-in, or contains one or more metacharacters.
+  # - An +exe_path+: the string path to an executable to be called.
+  # - An array containing a +command_line+ or an +exe_path+,
+  #   along with zero or more string arguments for the command.
+  #
+  # See {Argument command_line or exe_path}[rdoc-ref:Process@Argument+command_line+or+exe_path].
   #
   def pipeline_r(*cmds, &block)
     if Hash === cmds.last
@@ -485,33 +1115,82 @@ module Open3
   end
   module_function :pipeline_r
 
-  # Open3.pipeline_w starts a list of commands as a pipeline with a pipe
-  # which connects stdin of the first command.
+
+  # :call-seq:
+  #   Open3.pipeline_w([env, ] *cmds, options = {}) -> [first_stdin, wait_threads]
   #
-  #   Open3.pipeline_w(cmd1, cmd2, ... [, opts]) {|first_stdin, wait_threads|
-  #     ...
-  #   }
+  # Basically a wrapper for
+  # {Process.spawn}[rdoc-ref:Process.spawn]
+  # that:
   #
-  #   first_stdin, wait_threads = Open3.pipeline_w(cmd1, cmd2, ... [, opts])
-  #   ...
-  #   first_stdin.close
+  # - Creates a child process for each of the given +cmds+
+  #   by calling Process.spawn.
+  # - Pipes the +stdout+ from each child to the +stdin+ of the next child,
+  #   or, for the first child, pipes the caller's +stdout+ to the child's +stdin+.
   #
-  # Each cmd is a string or an array.
-  # If it is an array, the elements are passed to Process.spawn.
+  # The method does not wait for child processes to exit,
+  # so the caller must do so.
   #
-  #   cmd:
-  #     commandline                              command line string which is passed to a shell
-  #     [env, commandline, opts]                 command line string which is passed to a shell
-  #     [env, cmdname, arg1, ..., opts]          command name and one or more arguments (no shell)
-  #     [env, [cmdname, argv0], arg1, ..., opts] command name and arguments including argv[0] (no shell)
+  # With no block given, returns a 2-element array containing:
   #
-  #   Note that env and opts are optional, as Process.spawn.
+  # - The +stdin+ stream of the first child process.
+  # - An array of the wait threads for all of the child processes.
   #
   # Example:
   #
-  #   Open3.pipeline_w("bzip2 -c", :out=>"/tmp/hello.bz2") {|i, ts|
-  #     i.puts "hello"
-  #   }
+  #   first_stdin, wait_threads = Open3.pipeline_w('sort', 'cat -n')
+  #   # => [#<IO:fd 7>, [#<Process::Waiter:0x000055e8de928278 run>, #<Process::Waiter:0x000055e8de923e80 run>]]
+  #   first_stdin.puts("foo\nbar\nbaz")
+  #   first_stdin.close # Send EOF to sort.
+  #   wait_threads.each do |wait_thread|
+  #     wait_thread.join
+  #   end
+  #
+  # Output:
+  #
+  #   1	bar
+  #   2	baz
+  #   3	foo
+  #
+  # With a block given, calls the block with the +stdin+ stream
+  # of the first child process,
+  # and an array of the wait processes:
+  #
+  #   Open3.pipeline_w('sort', 'cat -n') do |first_stdin, wait_threads|
+  #     first_stdin.puts("foo\nbar\nbaz")
+  #     first_stdin.close # Send EOF to sort.
+  #     wait_threads.each do |wait_thread|
+  #       wait_thread.join
+  #     end
+  #   end
+  #
+  # Output:
+  #
+  #   1	bar
+  #   2	baz
+  #   3	foo
+  #
+  # Like Process.spawn, this method has potential security vulnerabilities
+  # if called with untrusted input;
+  # see {Command Injection}[rdoc-ref:command_injection.rdoc@Command+Injection].
+  #
+  # If the first argument is a hash, it becomes leading argument +env+
+  # in each call to Process.spawn;
+  # see {Execution Environment}[rdoc-ref:Process@Execution+Environment].
+  #
+  # If the last argument is a hash, it becomes trailing argument +options+
+  # in each call to Process.spawn;
+  # see {Execution Options}[rdoc-ref:Process@Execution+Options].
+  #
+  # Each remaining argument in +cmds+ is one of:
+  #
+  # - A +command_line+: a string that begins with a shell reserved word
+  #   or special built-in, or contains one or more metacharacters.
+  # - An +exe_path+: the string path to an executable to be called.
+  # - An array containing a +command_line+ or an +exe_path+,
+  #   along with zero or more string arguments for the command.
+  #
+  # See {Argument command_line or exe_path}[rdoc-ref:Process@Argument+command_line+or+exe_path].
   #
   def pipeline_w(*cmds, &block)
     if Hash === cmds.last
@@ -528,49 +1207,67 @@ module Open3
   end
   module_function :pipeline_w
 
-  # Open3.pipeline_start starts a list of commands as a pipeline.
-  # No pipe made for stdin of the first command and
-  # stdout of the last command.
+  # :call-seq:
+  #   Open3.pipeline_start([env, ] *cmds, options = {}) -> [wait_threads]
+  #
+  # Basically a wrapper for
+  # {Process.spawn}[rdoc-ref:Process.spawn]
+  # that:
   #
-  #   Open3.pipeline_start(cmd1, cmd2, ... [, opts]) {|wait_threads|
-  #     ...
-  #   }
+  # - Creates a child process for each of the given +cmds+
+  #   by calling Process.spawn.
+  # - Does not wait for child processes to exit.
   #
-  #   wait_threads = Open3.pipeline_start(cmd1, cmd2, ... [, opts])
-  #   ...
+  # With no block given, returns an array of the wait threads
+  # for all of the child processes.
   #
-  # Each cmd is a string or an array.
-  # If it is an array, the elements are passed to Process.spawn.
+  # Example:
+  #
+  #   wait_threads = Open3.pipeline_start('ls', 'grep R')
+  #   # => [#<Process::Waiter:0x000055e8de9d2bb0 run>, #<Process::Waiter:0x000055e8de9d2890 run>]
+  #   wait_threads.each do |wait_thread|
+  #     wait_thread.join
+  #   end
   #
-  #   cmd:
-  #     commandline                              command line string which is passed to a shell
-  #     [env, commandline, opts]                 command line string which is passed to a shell
-  #     [env, cmdname, arg1, ..., opts]          command name and one or more arguments (no shell)
-  #     [env, [cmdname, argv0], arg1, ..., opts] command name and arguments including argv[0] (no shell)
+  # Output:
   #
-  #   Note that env and opts are optional, as Process.spawn.
+  #   Rakefile
+  #   README.md
   #
-  # Example:
+  # With a block given, calls the block with an array of the wait processes:
+  #
+  #   Open3.pipeline_start('ls', 'grep R') do |wait_threads|
+  #     wait_threads.each do |wait_thread|
+  #       wait_thread.join
+  #     end
+  #   end
+  #
+  # Output:
+  #
+  #   Rakefile
+  #   README.md
+  #
+  # Like Process.spawn, this method has potential security vulnerabilities
+  # if called with untrusted input;
+  # see {Command Injection}[rdoc-ref:command_injection.rdoc@Command+Injection].
+  #
+  # If the first argument is a hash, it becomes leading argument +env+
+  # in each call to Process.spawn;
+  # see {Execution Environment}[rdoc-ref:Process@Execution+Environment].
+  #
+  # If the last argument is a hash, it becomes trailing argument +options+
+  # in each call to Process.spawn;
+  # see {Execution Options}[rdoc-ref:Process@Execution+Options].
   #
-  #   # run xeyes in 10 seconds.
-  #   Open3.pipeline_start("xeyes") {|ts|
-  #     sleep 10
-  #     t = ts[0]
-  #     Process.kill("TERM", t.pid)
-  #     p t.value #=> #<Process::Status: pid 911 SIGTERM (signal 15)>
-  #   }
-  #
-  #   # convert pdf to ps and send it to a printer.
-  #   # collect error message of pdftops and lpr.
-  #   pdf_file = "paper.pdf"
-  #   printer = "printer-name"
-  #   err_r, err_w = IO.pipe
-  #   Open3.pipeline_start(["pdftops", pdf_file, "-"],
-  #                        ["lpr", "-P#{printer}"],
-  #                        :err=>err_w) {|ts|
-  #     err_w.close
-  #     p err_r.read # error messages of pdftops and lpr.
-  #   }
+  # Each remaining argument in +cmds+ is one of:
+  #
+  # - A +command_line+: a string that begins with a shell reserved word
+  #   or special built-in, or contains one or more metacharacters.
+  # - An +exe_path+: the string path to an executable to be called.
+  # - An array containing a +command_line+ or an +exe_path+,
+  #   along with zero or more string arguments for the command.
+  #
+  # See {Argument command_line or exe_path}[rdoc-ref:Process@Argument+command_line+or+exe_path].
   #
   def pipeline_start(*cmds, &block)
     if Hash === cmds.last
@@ -588,57 +1285,51 @@ module Open3
   end
   module_function :pipeline_start
 
-  # Open3.pipeline starts a list of commands as a pipeline.
-  # It waits the finish of the commands.
-  # No pipe made for stdin of the first command and
-  # stdout of the last command.
+  # :call-seq:
+  #   Open3.pipeline([env, ] *cmds, options = {}) -> array_of_statuses
   #
-  #   status_list = Open3.pipeline(cmd1, cmd2, ... [, opts])
+  # Basically a wrapper for
+  # {Process.spawn}[rdoc-ref:Process.spawn]
+  # that:
   #
-  # Each cmd is a string or an array.
-  # If it is an array, the elements are passed to Process.spawn.
+  # - Creates a child process for each of the given +cmds+
+  #   by calling Process.spawn.
+  # - Pipes the +stdout+ from each child to the +stdin+ of the next child,
+  #   or, for the last child, to the caller's +stdout+.
+  # - Waits for the child processes to exit.
+  # - Returns an array of Process::Status objects (one for each child).
   #
-  #   cmd:
-  #     commandline                              command line string which is passed to a shell
-  #     [env, commandline, opts]                 command line string which is passed to a shell
-  #     [env, cmdname, arg1, ..., opts]          command name and one or more arguments (no shell)
-  #     [env, [cmdname, argv0], arg1, ..., opts] command name and arguments including argv[0] (no shell)
+  # Example:
   #
-  #   Note that env and opts are optional, as Process.spawn.
+  #   wait_threads = Open3.pipeline('ls', 'grep R')
+  #   # => [#<Process::Status: pid 2139200 exit 0>, #<Process::Status: pid 2139202 exit 0>]
   #
-  # Example:
+  # Output:
+  #
+  #   Rakefile
+  #   README.md
+  #
+  # Like Process.spawn, this method has potential security vulnerabilities
+  # if called with untrusted input;
+  # see {Command Injection}[rdoc-ref:command_injection.rdoc@Command+Injection].
+  #
+  # If the first argument is a hash, it becomes leading argument +env+
+  # in each call to Process.spawn;
+  # see {Execution Environment}[rdoc-ref:Process@Execution+Environment].
   #
-  #   fname = "/usr/share/man/man1/ruby.1.gz"
-  #   p Open3.pipeline(["zcat", fname], "nroff -man", "less")
-  #   #=> [#<Process::Status: pid 11817 exit 0>,
-  #   #    #<Process::Status: pid 11820 exit 0>,
-  #   #    #<Process::Status: pid 11828 exit 0>]
-  #
-  #   fname = "/usr/share/man/man1/ls.1.gz"
-  #   Open3.pipeline(["zcat", fname], "nroff -man", "colcrt")
-  #
-  #   # convert PDF to PS and send to a printer by lpr
-  #   pdf_file = "paper.pdf"
-  #   printer = "printer-name"
-  #   Open3.pipeline(["pdftops", pdf_file, "-"],
-  #                  ["lpr", "-P#{printer}"])
-  #
-  #   # count lines
-  #   Open3.pipeline("sort", "uniq -c", :in=>"names.txt", :out=>"count")
-  #
-  #   # cyclic pipeline
-  #   r,w = IO.pipe
-  #   w.print "ibase=14\n10\n"
-  #   Open3.pipeline("bc", "tee /dev/tty", :in=>r, :out=>w)
-  #   #=> 14
-  #   #   18
-  #   #   22
-  #   #   30
-  #   #   42
-  #   #   58
-  #   #   78
-  #   #   106
-  #   #   202
+  # If the last argument is a hash, it becomes trailing argument +options+
+  # in each call to Process.spawn'
+  # see {Execution Options}[rdoc-ref:Process@Execution+Options].
+  #
+  # Each remaining argument in +cmds+ is one of:
+  #
+  # - A +command_line+: a string that begins with a shell reserved word
+  #   or special built-in, or contains one or more metacharacters.
+  # - An +exe_path+: the string path to an executable to be called.
+  # - An array containing a +command_line+ or an +exe_path+,
+  #   along with zero or more string arguments for the command.
+  #
+  # See {Argument command_line or exe_path}[rdoc-ref:Process@Argument+command_line+or+exe_path].
   #
   def pipeline(*cmds)
     if Hash === cmds.last
@@ -648,12 +1339,12 @@ module Open3
     end
 
     pipeline_run(cmds, opts, [], []) {|ts|
-      ts.map {|t| t.value }
+      ts.map(&:value)
     }
   end
   module_function :pipeline
 
-  def pipeline_run(cmds, pipeline_opts, child_io, parent_io, &block) # :nodoc:
+  def pipeline_run(cmds, pipeline_opts, child_io, parent_io) # :nodoc:
     if cmds.empty?
       raise ArgumentError, "no commands"
     end
@@ -692,18 +1383,18 @@ module Open3
       end
       pid = spawn(*cmd, cmd_opts)
       wait_thrs << Process.detach(pid)
-      r.close if r
-      w2.close if w2
+      r&.close
+      w2&.close
       r = r2
     }
     result = parent_io + [wait_thrs]
-    child_io.each {|io| io.close }
+    child_io.each(&:close)
     if defined? yield
       begin
         return yield(*result)
       ensure
-        parent_io.each{|io| io.close unless io.closed?}
-        wait_thrs.each {|t| t.join }
+        parent_io.each(&:close)
+        wait_thrs.each(&:join)
       end
     end
     result
@@ -715,15 +1406,5 @@ module Open3
 
 end
 
-if $0 == __FILE__
-  a = Open3.popen3("nroff -man")
-  Thread.start do
-    while line = gets
-      a[0].print line
-    end
-    a[0].close
-  end
-  while line = a[1].gets
-    print ":", line
-  end
-end
+# JRuby uses different popen logic on Windows, require it here to reuse wrapper methods above.
+require 'open3/jruby_windows' if RUBY_ENGINE == 'jruby' && JRuby::Util::ON_WINDOWS
diff --git a/lib/open3/open3.gemspec b/lib/open3/open3.gemspec
new file mode 100644
index 0000000000..21980decac
--- /dev/null
+++ b/lib/open3/open3.gemspec
@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+name = File.basename(__FILE__, ".gemspec")
+version = ["lib", Array.new(name.count("-")+1, "..").join("/")].find do |dir|
+  break File.foreach(File.join(__dir__, dir, "#{name.tr('-', '/')}/version.rb")) do |line|
+    /^\s*VERSION\s*=\s*"(.*)"/ =~ line and break $1
+  end rescue nil
+end
+
+Gem::Specification.new do |spec|
+  spec.name          = name
+  spec.version       = version
+  spec.authors       = ["Yukihiro Matsumoto"]
+  spec.email         = ["matz@ruby-lang.org"]
+
+  spec.summary       = %q{Popen, but with stderr, too}
+  spec.description   = spec.summary
+  spec.homepage      = "https://github.com/ruby/open3"
+  spec.licenses      = ["Ruby", "BSD-2-Clause"]
+  spec.required_ruby_version = ">= 2.6.0"
+
+  spec.metadata["homepage_uri"] = spec.homepage
+  spec.metadata["source_code_uri"] = spec.homepage
+
+  # Specify which files should be added to the gem when it is released.
+  # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
+  spec.files         = Dir.chdir(File.expand_path('..', __FILE__)) do
+    `git ls-files -z 2>#{IO::NULL}`.split("\x0").reject { |f| f.match(%r{^(test|spec|features)/}) }
+  end
+  spec.bindir        = "exe"
+  spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
+  spec.require_paths = ["lib"]
+end
diff --git a/lib/open3/version.rb b/lib/open3/version.rb
new file mode 100644
index 0000000000..322dd71e2a
--- /dev/null
+++ b/lib/open3/version.rb
@@ -0,0 +1,4 @@
+module Open3
+  # The version string
+  VERSION = "0.2.1"
+end
diff --git a/lib/optionparser.rb b/lib/optionparser.rb
new file mode 100644
index 0000000000..4b9b40d82a
--- /dev/null
+++ b/lib/optionparser.rb
@@ -0,0 +1,2 @@
+# frozen_string_literal: false
+require_relative 'optparse'
diff --git a/lib/optparse.rb b/lib/optparse.rb
index 9eec54c027..97178e284b 100644
--- a/lib/optparse.rb
+++ b/lib/optparse.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 #
 # optparse.rb - command-line option analysis with the OptionParser class.
 #
@@ -6,8 +7,9 @@
 #
 # See OptionParser for documentation.
 #
+require 'set' unless defined?(Set)
 
-
+#--
 # == Developer Documentation (not for RDoc output)
 #
 # === Class tree
@@ -42,8 +44,14 @@
 #                         | all instances)|
 #                         +---------------+
 #
+#++
+#
 # == OptionParser
 #
+# === New to +OptionParser+?
+#
+# See the {Tutorial}[optparse/tutorial.rdoc].
+#
 # === Introduction
 #
 # OptionParser is a class for command-line option analysis.  It is much more
@@ -68,10 +76,10 @@
 #   require 'optparse'
 #
 #   options = {}
-#   OptionParser.new do |opts|
-#     opts.banner = "Usage: example.rb [options]"
+#   OptionParser.new do |parser|
+#     parser.banner = "Usage: example.rb [options]"
 #
-#     opts.on("-v", "--[no-]verbose", "Run verbosely") do |v|
+#     parser.on("-v", "--[no-]verbose", "Run verbosely") do |v|
 #       options[:verbose] = v
 #     end
 #   end.parse!
@@ -79,6 +87,181 @@
 #   p options
 #   p ARGV
 #
+# === Generating Help
+#
+# OptionParser can be used to automatically generate help for the commands you
+# write:
+#
+#   require 'optparse'
+#
+#   Options = Struct.new(:name)
+#
+#   class Parser
+#     def self.parse(options)
+#       args = Options.new("world")
+#
+#       opt_parser = OptionParser.new do |parser|
+#         parser.banner = "Usage: example.rb [options]"
+#
+#         parser.on("-nNAME", "--name=NAME", "Name to say hello to") do |n|
+#           args.name = n
+#         end
+#
+#         parser.on("-h", "--help", "Prints this help") do
+#           puts parser
+#           exit
+#         end
+#       end
+#
+#       opt_parser.parse!(options)
+#       return args
+#     end
+#   end
+#   options = Parser.parse %w[--help]
+#
+#   #=>
+#      # Usage: example.rb [options]
+#      #     -n, --name=NAME                  Name to say hello to
+#      #     -h, --help                       Prints this help
+#
+# === Required Arguments
+#
+# For options that require an argument, option specification strings may include an
+# option name in all caps. If an option is used without the required argument,
+# an exception will be raised.
+#
+#   require 'optparse'
+#
+#   options = {}
+#   OptionParser.new do |parser|
+#     parser.on("-r", "--require LIBRARY",
+#               "Require the LIBRARY before executing your script") do |lib|
+#       puts "You required #{lib}!"
+#     end
+#   end.parse!
+#
+# Used:
+#
+#   $ ruby optparse-test.rb -r
+#   optparse-test.rb:9:in '<main>': missing argument: -r (OptionParser::MissingArgument)
+#   $ ruby optparse-test.rb -r my-library
+#   You required my-library!
+#
+# === Type Coercion
+#
+# OptionParser supports the ability to coerce command line arguments
+# into objects for us.
+#
+# OptionParser comes with a few ready-to-use kinds of type
+# coercion. They are:
+#
+# - Date  -- Anything accepted by +Date.parse+ (need to require +optparse/date+)
+# - DateTime -- Anything accepted by +DateTime.parse+ (need to require +optparse/date+)
+# - Time -- Anything accepted by +Time.httpdate+ or +Time.parse+ (need to require +optparse/time+)
+# - URI  -- Anything accepted by +URI.parse+ (need to require +optparse/uri+)
+# - Shellwords -- Anything accepted by +Shellwords.shellwords+ (need to require +optparse/shellwords+)
+# - String -- Any non-empty string
+# - Integer -- Any integer. Will convert octal. (e.g. 124, -3, 040)
+# - Float -- Any float. (e.g. 10, 3.14, -100E+13)
+# - Numeric -- Any integer, float, or rational (1, 3.4, 1/3)
+# - DecimalInteger -- Like +Integer+, but no octal format.
+# - OctalInteger -- Like +Integer+, but no decimal format.
+# - DecimalNumeric -- Decimal integer or float.
+# - TrueClass --  Accepts '+, yes, true, -, no, false' and
+#   defaults as +true+
+# - FalseClass -- Same as +TrueClass+, but defaults to +false+
+# - Array -- Strings separated by ',' (e.g. 1,2,3)
+# - Regexp -- Regular expressions. Also includes options.
+#
+# We can also add our own coercions, which we will cover below.
+#
+# ==== Using Built-in Conversions
+#
+# As an example, the built-in +Time+ conversion is used. The other built-in
+# conversions behave in the same way.
+# OptionParser will attempt to parse the argument
+# as a +Time+. If it succeeds, that time will be passed to the
+# handler block. Otherwise, an exception will be raised.
+#
+#   require 'optparse'
+#   require 'optparse/time'
+#   OptionParser.new do |parser|
+#     parser.on("-t", "--time [TIME]", Time, "Begin execution at given time") do |time|
+#       p time
+#     end
+#   end.parse!
+#
+# Used:
+#
+#   $ ruby optparse-test.rb  -t nonsense
+#   ... invalid argument: -t nonsense (OptionParser::InvalidArgument)
+#   $ ruby optparse-test.rb  -t 10-11-12
+#   2010-11-12 00:00:00 -0500
+#   $ ruby optparse-test.rb  -t 9:30
+#   2014-08-13 09:30:00 -0400
+#
+# ==== Creating Custom Conversions
+#
+# The +accept+ method on OptionParser may be used to create converters.
+# It specifies which conversion block to call whenever a class is specified.
+# The example below uses it to fetch a +User+ object before the +on+ handler receives it.
+#
+#   require 'optparse'
+#
+#   User = Struct.new(:id, :name)
+#
+#   def find_user id
+#     not_found = ->{ raise "No User Found for id #{id}" }
+#     [ User.new(1, "Sam"),
+#       User.new(2, "Gandalf") ].find(not_found) do |u|
+#       u.id == id
+#     end
+#   end
+#
+#   op = OptionParser.new
+#   op.accept(User) do |user_id|
+#     find_user user_id.to_i
+#   end
+#
+#   op.on("--user ID", User) do |user|
+#     puts user
+#   end
+#
+#   op.parse!
+#
+# Used:
+#
+#   $ ruby optparse-test.rb --user 1
+#   #<struct User id=1, name="Sam">
+#   $ ruby optparse-test.rb --user 2
+#   #<struct User id=2, name="Gandalf">
+#   $ ruby optparse-test.rb --user 3
+#   optparse-test.rb:15:in 'block in find_user': No User Found for id 3 (RuntimeError)
+#
+# === Store options to a Hash
+#
+# The +into+ option of +order+, +parse+ and so on methods stores command line options into a Hash.
+#
+#   require 'optparse'
+#
+#   options = {}
+#   OptionParser.new do |parser|
+#     parser.on('-a')
+#     parser.on('-b NUM', Integer)
+#     parser.on('-v', '--verbose')
+#   end.parse!(into: options)
+#
+#   p options
+#
+# Used:
+#
+#   $ ruby optparse-test.rb -a
+#   {:a=>true}
+#   $ ruby optparse-test.rb -a -v
+#   {:a=>true, :verbose=>true}
+#   $ ruby optparse-test.rb -a -b 100
+#   {:a=>true, :b=>100}
+#
 # === Complete example
 #
 # The following example is a complete Ruby program.  You can run it and see the
@@ -91,110 +274,143 @@
 #   require 'pp'
 #
 #   class OptparseExample
+#     Version = '1.0.0'
 #
 #     CODES = %w[iso-2022-jp shift_jis euc-jp utf8 binary]
 #     CODE_ALIASES = { "jis" => "iso-2022-jp", "sjis" => "shift_jis" }
 #
-#     #
-#     # Return a structure describing the options.
-#     #
-#     def self.parse(args)
-#       # The options specified on the command line will be collected in *options*.
-#       # We set default values here.
-#       options = OpenStruct.new
-#       options.library = []
-#       options.inplace = false
-#       options.encoding = "utf8"
-#       options.transfer_type = :auto
-#       options.verbose = false
-#
-#       opts = OptionParser.new do |opts|
-#         opts.banner = "Usage: example.rb [options]"
-#
-#         opts.separator ""
-#         opts.separator "Specific options:"
-#
-#         # Mandatory argument.
-#         opts.on("-r", "--require LIBRARY",
-#                 "Require the LIBRARY before executing your script") do |lib|
-#           options.library << lib
+#     class ScriptOptions
+#       attr_accessor :library, :inplace, :encoding, :transfer_type,
+#                     :verbose, :extension, :delay, :time, :record_separator,
+#                     :list
+#
+#       def initialize
+#         self.library = []
+#         self.inplace = false
+#         self.encoding = "utf8"
+#         self.transfer_type = :auto
+#         self.verbose = false
+#       end
+#
+#       def define_options(parser)
+#         parser.banner = "Usage: example.rb [options]"
+#         parser.separator ""
+#         parser.separator "Specific options:"
+#
+#         # add additional options
+#         perform_inplace_option(parser)
+#         delay_execution_option(parser)
+#         execute_at_time_option(parser)
+#         specify_record_separator_option(parser)
+#         list_example_option(parser)
+#         specify_encoding_option(parser)
+#         optional_option_argument_with_keyword_completion_option(parser)
+#         boolean_verbose_option(parser)
+#
+#         parser.separator ""
+#         parser.separator "Common options:"
+#         # No argument, shows at tail.  This will print an options summary.
+#         # Try it and see!
+#         parser.on_tail("-h", "--help", "Show this message") do
+#           puts parser
+#           exit
+#         end
+#         # Another typical switch to print the version.
+#         parser.on_tail("--version", "Show version") do
+#           puts Version
+#           exit
 #         end
+#       end
 #
-#         # Optional argument; multi-line description.
-#         opts.on("-i", "--inplace [EXTENSION]",
-#                 "Edit ARGV files in place",
-#                 "  (make backup if EXTENSION supplied)") do |ext|
-#           options.inplace = true
-#           options.extension = ext || ''
-#           options.extension.sub!(/\A\.?(?=.)/, ".")  # Ensure extension begins with dot.
+#       def perform_inplace_option(parser)
+#         # Specifies an optional option argument
+#         parser.on("-i", "--inplace [EXTENSION]",
+#                   "Edit ARGV files in place",
+#                   "(make backup if EXTENSION supplied)") do |ext|
+#           self.inplace = true
+#           self.extension = ext || ''
+#           self.extension.sub!(/\A\.?(?=.)/, ".")  # Ensure extension begins with dot.
 #         end
+#       end
 #
+#       def delay_execution_option(parser)
 #         # Cast 'delay' argument to a Float.
-#         opts.on("--delay N", Float, "Delay N seconds before executing") do |n|
-#           options.delay = n
+#         parser.on("--delay N", Float, "Delay N seconds before executing") do |n|
+#           self.delay = n
 #         end
+#       end
 #
+#       def execute_at_time_option(parser)
 #         # Cast 'time' argument to a Time object.
-#         opts.on("-t", "--time [TIME]", Time, "Begin execution at given time") do |time|
-#           options.time = time
+#         parser.on("-t", "--time [TIME]", Time, "Begin execution at given time") do |time|
+#           self.time = time
 #         end
+#       end
 #
+#       def specify_record_separator_option(parser)
 #         # Cast to octal integer.
-#         opts.on("-F", "--irs [OCTAL]", OptionParser::OctalInteger,
-#                 "Specify record separator (default \\0)") do |rs|
-#           options.record_separator = rs
+#         parser.on("-F", "--irs [OCTAL]", OptionParser::OctalInteger,
+#                   "Specify record separator (default \\0)") do |rs|
+#           self.record_separator = rs
 #         end
+#       end
 #
+#       def list_example_option(parser)
 #         # List of arguments.
-#         opts.on("--list x,y,z", Array, "Example 'list' of arguments") do |list|
-#           options.list = list
+#         parser.on("--list x,y,z", Array, "Example 'list' of arguments") do |list|
+#           self.list = list
 #         end
+#       end
 #
+#       def specify_encoding_option(parser)
 #         # Keyword completion.  We are specifying a specific set of arguments (CODES
 #         # and CODE_ALIASES - notice the latter is a Hash), and the user may provide
 #         # the shortest unambiguous text.
-#         code_list = (CODE_ALIASES.keys + CODES).join(',')
-#         opts.on("--code CODE", CODES, CODE_ALIASES, "Select encoding",
-#                 "  (#{code_list})") do |encoding|
-#           options.encoding = encoding
+#         code_list = (CODE_ALIASES.keys + CODES).join(', ')
+#         parser.on("--code CODE", CODES, CODE_ALIASES, "Select encoding",
+#                   "(#{code_list})") do |encoding|
+#           self.encoding = encoding
 #         end
+#       end
 #
-#         # Optional argument with keyword completion.
-#         opts.on("--type [TYPE]", [:text, :binary, :auto],
-#                 "Select transfer type (text, binary, auto)") do |t|
-#           options.transfer_type = t
+#       def optional_option_argument_with_keyword_completion_option(parser)
+#         # Optional '--type' option argument with keyword completion.
+#         parser.on("--type [TYPE]", [:text, :binary, :auto],
+#                   "Select transfer type (text, binary, auto)") do |t|
+#           self.transfer_type = t
 #         end
+#       end
 #
+#       def boolean_verbose_option(parser)
 #         # Boolean switch.
-#         opts.on("-v", "--[no-]verbose", "Run verbosely") do |v|
-#           options.verbose = v
+#         parser.on("-v", "--[no-]verbose", "Run verbosely") do |v|
+#           self.verbose = v
 #         end
+#       end
+#     end
 #
-#         opts.separator ""
-#         opts.separator "Common options:"
-#
-#         # No argument, shows at tail.  This will print an options summary.
-#         # Try it and see!
-#         opts.on_tail("-h", "--help", "Show this message") do
-#           puts opts
-#           exit
-#         end
+#     #
+#     # Return a structure describing the options.
+#     #
+#     def parse(args)
+#       # The options specified on the command line will be collected in
+#       # *options*.
 #
-#         # Another typical switch to print the version.
-#         opts.on_tail("--version", "Show version") do
-#           puts OptionParser::Version.join('.')
-#           exit
-#         end
+#       @options = ScriptOptions.new
+#       @args = OptionParser.new do |parser|
+#         @options.define_options(parser)
+#         parser.parse!(args)
 #       end
+#       @options
+#     end
 #
-#       opts.parse!(args)
-#       options
-#     end  # parse()
-#
+#     attr_reader :parser, :options
 #   end  # class OptparseExample
 #
-#   options = OptparseExample.parse(ARGV)
-#   pp options
+#   example = OptparseExample.new
+#   options = example.parse(ARGV)
+#   pp options # example.options
+#   pp ARGV
 #
 # === Shell Completion
 #
@@ -203,17 +419,18 @@
 #
 # === Further documentation
 #
-# The above examples should be enough to learn how to use this class.  If you
-# have any questions, email me (gsinclair@soyabean.com.au) and I will update
-# this document.
+# The above examples, along with the accompanying
+# {Tutorial}[optparse/tutorial.rdoc],
+# should be enough to learn how to use this class.
+# If you have any questions, file a ticket at http://bugs.ruby-lang.org.
 #
 class OptionParser
-  # :stopdoc:
-  RCSID = %w$Id$[1..-1].each {|s| s.freeze}.freeze
-  Version = (RCSID[1].split('.').collect {|s| s.to_i}.extend(Comparable).freeze if RCSID[1])
-  LastModified = (Time.gm(*RCSID[2, 2].join('-').scan(/\d+/).collect {|s| s.to_i}) if RCSID[2])
-  Release = RCSID[2]
+  # The version string
+  VERSION = "0.8.1"
+  # An alias for compatibility
+  Version = VERSION
 
+  # :stopdoc:
   NoArgument = [NO_ARGUMENT = :NONE, nil].freeze
   RequiredArgument = [REQUIRED_ARGUMENT = :REQUIRED, true].freeze
   OptionalArgument = [OPTIONAL_ARGUMENT = :OPTIONAL, false].freeze
@@ -224,6 +441,8 @@ class OptionParser
   # and resolved against a list of acceptable values.
   #
   module Completion
+    # :nodoc:
+
     def self.regexp(key, icase)
       Regexp.new('\A' + Regexp.quote(key).gsub(/\w+\b/, '\&\w*'), icase)
     end
@@ -233,7 +452,7 @@ class OptionParser
       candidates = []
       block.call do |k, *v|
         (if Regexp === k
-           kn = nil
+           kn = ""
            k === key
          else
            kn = defined?(k.id2name) ? k.id2name : k
@@ -245,11 +464,14 @@ class OptionParser
       candidates
     end
 
-    def candidate(key, icase = false, pat = nil)
+    def self.completable?(key)
+      String.try_convert(key) or defined?(key.id2name)
+    end
+
+    def candidate(key, icase = false, pat = nil, &_)
       Completion.candidate(key, icase, pat, &method(:each))
     end
 
-    public
     def complete(key, icase = false, pat = nil)
       candidates = candidate(key, icase, pat, &method(:each)).sort_by {|k, v, kn| kn.size}
       if candidates.size == 1
@@ -280,7 +502,6 @@ class OptionParser
     end
   end
 
-
   #
   # Map from option/keyword string to object with completion.
   #
@@ -288,7 +509,6 @@ class OptionParser
     include Completion
   end
 
-
   #
   # Individual switch class.  Not important to the user.
   #
@@ -296,6 +516,8 @@ class OptionParser
   # RequiredArgument, etc.
   #
   class Switch
+    # :nodoc:
+
     attr_reader :pattern, :conv, :short, :long, :arg, :desc, :block
 
     #
@@ -328,17 +550,18 @@ class OptionParser
 
     def initialize(pattern = nil, conv = nil,
                    short = nil, long = nil, arg = nil,
-                   desc = ([] if short or long), block = Proc.new)
+                   desc = ([] if short or long), block = nil, values = nil, &_block)
       raise if Array === pattern
-      @pattern, @conv, @short, @long, @arg, @desc, @block =
-        pattern, conv, short, long, arg, desc, block
+      block ||= _block
+      @pattern, @conv, @short, @long, @arg, @desc, @block, @values =
+        pattern, conv, short, long, arg, desc, block, values
     end
 
     #
     # Parses +arg+ and returns rest of +arg+ and matched portion to the
     # argument pattern. Yields when the pattern doesn't match substring.
     #
-    def parse_arg(arg)
+    private def parse_arg(arg) # :nodoc:
       pattern or return nil, [arg]
       unless m = pattern.match(arg)
         yield(InvalidArgument, arg)
@@ -356,22 +579,24 @@ class OptionParser
       yield(InvalidArgument, arg) # didn't match whole arg
       return arg[s.length..-1], m
     end
-    private :parse_arg
 
     #
     # Parses argument, converts and returns +arg+, +block+ and result of
     # conversion. Yields at semi-error condition instead of raising an
     # exception.
     #
-    def conv_arg(arg, val = [])
+    private def conv_arg(arg, val = []) # :nodoc:
+      v, = *val
       if conv
         val = conv.call(*val)
       else
         val = proc {|v| v}.call(*val)
       end
+      if @values
+        @values.include?(val) or raise InvalidArgument, v
+      end
       return arg, block, val
     end
-    private :conv_arg
 
     #
     # Produces the summary text. Each line of the summary is yielded to the
@@ -385,7 +610,7 @@ class OptionParser
     #            +max+ columns.
     # +indent+:: Prefix string indents all summarized lines.
     #
-    def summarize(sdone = [], ldone = [], width = 1, max = width - 1, indent = "")
+    def summarize(sdone = {}, ldone = {}, width = 1, max = width - 1, indent = "")
       sopts, lopts = [], [], nil
       @short.each {|s| sdone.fetch(s) {sopts << s}; sdone[s] = true} if @short
       @long.each {|s| ldone.fetch(s) {lopts << s}; ldone[s] = true} if @long
@@ -397,8 +622,8 @@ class OptionParser
       while s = lopts.shift
         l = left[-1].length + s.length
         l += arg.length if left.size == 1 && arg
-        l < max or sopts.empty? or left << ''
-        left[-1] << if left[-1].empty? then ' ' * 4 else ', ' end << s
+        l < max or sopts.empty? or left << +''
+        left[-1] << (left[-1].empty? ? ' ' * 4 : ', ') << s
       end
 
       if arg
@@ -448,8 +673,8 @@ class OptionParser
       return if sopts.empty? and lopts.empty? # completely hidden
 
       (sopts+lopts).each do |opt|
-        # "(-x -c -r)-l[left justify]" \
-        if opt =~ /^--\[no-\](.+)$/
+        # "(-x -c -r)-l[left justify]"
+        if /\A--\[no-\](.+)$/ =~ opt
           o = $1
           yield("--#{o}", desc.join(""))
           yield("--no-#{o}", desc.join(""))
@@ -459,6 +684,34 @@ class OptionParser
       end
     end
 
+    def pretty_print_contents(q) # :nodoc:
+      if @block
+        q.text ":" + @block.source_location.join(":") + ":"
+        first = false
+      else
+        first = true
+      end
+      [@short, @long].each do |list|
+        list.each do |opt|
+          if first
+            q.text ":"
+            first = false
+          end
+          q.breakable
+          q.text opt
+        end
+      end
+    end
+
+    def pretty_print(q)         # :nodoc:
+      q.object_group(self) {pretty_print_contents(q)}
+    end
+
+    def omitted_argument(val)   # :nodoc:
+      val.pop if val.size == 3 and val.last.nil?
+      val
+    end
+
     #
     # Switch that takes no arguments.
     #
@@ -472,12 +725,16 @@ class OptionParser
         conv_arg(arg)
       end
 
-      def self.incompatible_argument_styles(*)
+      def self.incompatible_argument_styles(*) # :nodoc:
       end
 
-      def self.pattern
+      def self.pattern          # :nodoc:
         Object
       end
+
+      def pretty_head           # :nodoc:
+        "NoArgument"
+      end
     end
 
     #
@@ -488,13 +745,17 @@ class OptionParser
       #
       # Raises an exception if argument is not present.
       #
-      def parse(arg, argv)
+      def parse(arg, argv, &_)
         unless arg
           raise MissingArgument if argv.empty?
           arg = argv.shift
         end
         conv_arg(*parse_arg(arg, &method(:raise)))
       end
+
+      def pretty_head           # :nodoc:
+        "Required"
+      end
     end
 
     #
@@ -509,32 +770,41 @@ class OptionParser
         if arg
           conv_arg(*parse_arg(arg, &error))
         else
-          conv_arg(arg)
+          omitted_argument conv_arg(arg)
         end
       end
+
+      def pretty_head           # :nodoc:
+        "Optional"
+      end
     end
 
     #
-    # Switch that takes an argument, which does not begin with '-'.
+    # Switch that takes an argument, which does not begin with '-' or is '-'.
     #
     class PlacedArgument < self
 
       #
-      # Returns nil if argument is not present or begins with '-'.
+      # Returns nil if argument is not present or begins with '-' and is not '-'.
       #
       def parse(arg, argv, &error)
-        if !(val = arg) and (argv.empty? or /\A-/ =~ (val = argv[0]))
-          return nil, block, nil
+        if !(val = arg) and (argv.empty? or /\A-./ =~ (val = argv[0]))
+          return nil, block
         end
         opt = (val = parse_arg(val, &error))[1]
         val = conv_arg(*val)
         if opt and !arg
           argv.shift
         else
+          omitted_argument val
           val[0] = nil
         end
         val
       end
+
+      def pretty_head           # :nodoc:
+        "Placed"
+      end
     end
   end
 
@@ -544,6 +814,8 @@ class OptionParser
   # matching pattern and converter pair. Also provides summary feature.
   #
   class List
+    # :nodoc:
+
     # Map from acceptable argument types to pattern and converter pairs.
     attr_reader :atype
 
@@ -566,13 +838,24 @@ class OptionParser
       @list = []
     end
 
+    def pretty_print(q)         # :nodoc:
+      q.group(1, "(", ")") do
+        @list.each do |sw|
+          next unless Switch === sw
+          q.group(1, "(" + sw.pretty_head, ")") do
+            sw.pretty_print_contents(q)
+          end
+        end
+      end
+    end
+
     #
     # See OptionParser.accept.
     #
     def accept(t, pat = /.*/m, &block)
       if pat
         pat.respond_to?(:match) or
-          raise TypeError, "has no `match'", ParseError.filter_backtrace(caller(2))
+          raise TypeError, "has no 'match'", ParseError.filter_backtrace(caller(2))
       else
         pat = t if t.respond_to?(:match)
       end
@@ -597,14 +880,13 @@ class OptionParser
     # +lopts+::  Long style option list.
     # +nlopts+:: Negated long style options list.
     #
-    def update(sw, sopts, lopts, nsw = nil, nlopts = nil)
+    private def update(sw, sopts, lopts, nsw = nil, nlopts = nil) # :nodoc:
       sopts.each {|o| @short[o] = sw} if sopts
       lopts.each {|o| @long[o] = sw} if lopts
       nlopts.each {|o| @long[o] = nsw} if nsw and nlopts
       used = @short.invert.update(@long.invert)
       @list.delete_if {|o| Switch === o and !used[o]}
     end
-    private :update
 
     #
     # Inserts +switch+ at the head of the list, and associates short, long
@@ -659,6 +941,10 @@ class OptionParser
       __send__(id).complete(opt, icase, *pat, &block)
     end
 
+    def get_candidates(id)
+      yield __send__(id).keys
+    end
+
     #
     # Iterates over each option, passing the option to the +block+.
     #
@@ -734,7 +1020,7 @@ class OptionParser
   # OPTIONAL_ARGUMENT:: The switch requires an optional argument. (:OPTIONAL)
   #
   # Use like --switch=argument (long style) or -Xargument (short style). For
-  # short style, only portion matched to argument pattern is dealed as
+  # short style, only portion matched to argument pattern is treated as
   # argument.
   #
   ArgumentStyle = {}
@@ -751,7 +1037,6 @@ class OptionParser
   DefaultList.short['-'] = Switch::NoArgument.new {}
   DefaultList.long[''] = Switch::NoArgument.new {throw :terminate}
 
-
   COMPSYS_HEADER = <<'XXX'      # :nodoc:
 
 typeset -A opt_args
@@ -764,11 +1049,31 @@ XXX
     to << "#compdef #{name}\n"
     to << COMPSYS_HEADER
     visit(:compsys, {}, {}) {|o, d|
-      to << %Q[  "#{o}[#{d.gsub(/[\"\[\]]/, '\\\\\&')}]" \\\n]
+      to << %Q[  "#{o}[#{d.gsub(/[\\\"\[\]]/, '\\\\\&')}]" \\\n]
     }
     to << "  '*:file:_files' && return 0\n"
   end
 
+  def help_exit
+    if $stdout.tty? && (pager = ENV.values_at(*%w[RUBY_PAGER PAGER]).find {|e| e && !e.empty?})
+      less = ENV["LESS"]
+      args = [{"LESS" => "#{less} -Fe"}, pager, "w"]
+      print = proc do |f|
+        f.puts help
+      rescue Errno::EPIPE
+        # pager terminated
+      end
+      if Process.respond_to?(:fork) and false
+        IO.popen("-") {|f| f ? Process.exec(*args, in: f) : print.call($stdout)}
+        # unreachable
+      end
+      IO.popen(*args, &print)
+    else
+      puts help
+    end
+    exit
+  end
+
   #
   # Default options for ARGV, which never appear in option summary.
   #
@@ -780,8 +1085,7 @@ XXX
   #
   Officious['help'] = proc do |parser|
     Switch::NoArgument.new do |arg|
-      puts parser.help
-      exit
+      parser.help_exit
     end
   end
 
@@ -802,7 +1106,7 @@ XXX
   #
   Officious['*-completion-zsh'] = proc do |parser|
     Switch::OptionalArgument.new do |arg|
-      parser.compsys(STDOUT, arg)
+      parser.compsys($stdout, arg)
       exit
     end
   end
@@ -815,7 +1119,7 @@ XXX
     Switch::OptionalArgument.new do |pkg|
       if pkg
         begin
-          require 'optparse/version'
+          require_relative 'optparse/version'
         rescue LoadError
         else
           show_version(*pkg.split(/,/)) or
@@ -860,6 +1164,10 @@ XXX
       default.to_i + 1
     end
   end
+
+  #
+  # See self.inc
+  #
   def inc(*args)
     self.class.inc(*args)
   end
@@ -878,6 +1186,8 @@ XXX
     @summary_width = width
     @summary_indent = indent
     @default_argv = ARGV
+    @require_exact = false
+    @raise_unknown = true
     add_officious
     yield self if block_given?
   end
@@ -896,11 +1206,19 @@ XXX
   def terminate(arg = nil)
     self.class.terminate(arg)
   end
+  #
+  # See #terminate.
+  #
   def self.terminate(arg = nil)
     throw :terminate, arg
   end
 
   @stack = [DefaultList]
+  #
+  # Returns the global top option list.
+  #
+  # Do not use directly.
+  #
   def self.top() DefaultList end
 
   #
@@ -921,9 +1239,9 @@ XXX
   #
   # Directs to reject specified class argument.
   #
-  # +t+:: Argument class specifier, any object including Class.
+  # +type+:: Argument class specifier, any object including Class.
   #
-  #   reject(t)
+  #   reject(type)
   #
   def reject(*args, &blk) top.reject(*args, &blk) end
   #
@@ -951,12 +1269,19 @@ XXX
   # Strings to be parsed in default.
   attr_accessor :default_argv
 
+  # Whether to require that options match exactly (disallows providing
+  # abbreviated long option as short option).
+  attr_accessor :require_exact
+
+  # Whether to raise at unknown option.
+  attr_accessor :raise_unknown
+
   #
   # Heading banner preceding summary.
   #
   def banner
     unless @banner
-      @banner = "Usage: #{program_name} [options]"
+      @banner = +"Usage: #{program_name} [options]"
       visit(:add_banner, @banner)
     end
     @banner
@@ -967,7 +1292,15 @@ XXX
   # to $0.
   #
   def program_name
-    @program_name || File.basename($0, '.*')
+    @program_name || strip_ext(File.basename($0))
+  end
+
+  private def strip_ext(name)  # :nodoc:
+    exts = /#{
+      require "rbconfig"
+      Regexp.union(*RbConfig::CONFIG["EXECUTABLE_EXTS"]&.split(" "))
+    }\z/o
+    name.sub(exts, "")
   end
 
   # for experimental cascading :-)
@@ -985,14 +1318,14 @@ XXX
   # Version
   #
   def version
-    @version || (defined?(::Version) && ::Version)
+    (defined?(@version) && @version) || (defined?(::Version) && ::Version)
   end
 
   #
   # Release code
   #
   def release
-    @release || (defined?(::Release) && ::Release) || (defined?(::RELEASE) && ::RELEASE)
+    (defined?(@release) && @release) || (defined?(::Release) && ::Release) || (defined?(::RELEASE) && ::RELEASE)
   end
 
   #
@@ -1000,16 +1333,30 @@ XXX
   #
   def ver
     if v = version
-      str = "#{program_name} #{[v].join('.')}"
+      str = +"#{program_name} #{[v].join('.')}"
       str << " (#{v})" if v = release
       str
     end
   end
 
+  #
+  # Shows warning message with the program name
+  #
+  # +mesg+:: Message, defaulted to +$!+.
+  #
+  # See Kernel#warn.
+  #
   def warn(mesg = $!)
     super("#{program_name}: #{mesg}")
   end
 
+  #
+  # Shows message with the program name then aborts.
+  #
+  # +mesg+:: Message, defaulted to +$!+.
+  #
+  # See Kernel#abort.
+  #
   def abort(mesg = $!)
     super("#{program_name}: #{mesg}")
   end
@@ -1031,6 +1378,9 @@ XXX
   #
   # Pushes a new List.
   #
+  # If a block is given, yields +self+ and returns the result of the
+  # block, otherwise returns +self+.
+  #
   def new
     @stack.push(List.new)
     if block_given?
@@ -1057,7 +1407,8 @@ XXX
   # +indent+:: Indentation, defaults to @summary_indent.
   #
   def summarize(to = [], width = @summary_width, max = width - 1, indent = @summary_indent, &blk)
-    blk ||= proc {|l| to << (l.index($/, -1) ? l : l + $/)}
+    nl = "\n"
+    blk ||= proc {|l| to << (l.index(nl, -1) ? l : l + nl)}
     visit(:summarize, {}, {}, width, max, indent, &blk)
     to
   end
@@ -1068,6 +1419,29 @@ XXX
   def help; summarize("#{banner}".sub(/\n?\z/, "\n")) end
   alias to_s help
 
+  def pretty_print(q)           # :nodoc:
+    q.object_group(self) do
+      first = true
+      if @stack.size > 2
+        @stack.each_with_index do |s, i|
+          next if i < 2
+          next if s.list.empty?
+          if first
+            first = false
+            q.text ":"
+          end
+          q.breakable
+          s.pretty_print(q)
+        end
+      end
+    end
+  end
+
+  def inspect                   # :nodoc:
+    require 'pp'
+    pretty_print_inspect
+  end
+
   #
   # Returns option summary list.
   #
@@ -1081,73 +1455,20 @@ XXX
   # +prv+:: Previously specified argument.
   # +msg+:: Exception message.
   #
-  def notwice(obj, prv, msg)
+  private def notwice(obj, prv, msg) # :nodoc:
     unless !prv or prv == obj
       raise(ArgumentError, "argument #{msg} given twice: #{obj}",
             ParseError.filter_backtrace(caller(2)))
     end
     obj
   end
-  private :notwice
-
-  SPLAT_PROC = proc {|*a| a.length <= 1 ? a.first : a}
-  #
-  # Creates an OptionParser::Switch from the parameters. The parsed argument
-  # value is passed to the given block, where it can be processed.
-  #
-  # See at the beginning of OptionParser for some full examples.
-  #
-  # +opts+ can include the following elements:
-  #
-  # [Argument style:]
-  #   One of the following:
-  #     :NONE, :REQUIRED, :OPTIONAL
-  #
-  # [Argument pattern:]
-  #   Acceptable option argument format, must be pre-defined with
-  #   OptionParser.accept or OptionParser#accept, or Regexp. This can appear
-  #   once or assigned as String if not present, otherwise causes an
-  #   ArgumentError. Examples:
-  #     Float, Time, Array
-  #
-  # [Possible argument values:]
-  #   Hash or Array.
-  #     [:text, :binary, :auto]
-  #     %w[iso-2022-jp shift_jis euc-jp utf8 binary]
-  #     { "jis" => "iso-2022-jp", "sjis" => "shift_jis" }
-  #
-  # [Long style switch:]
-  #   Specifies a long style switch which takes a mandatory, optional or no
-  #   argument. It's a string of the following form:
-  #     "--switch=MANDATORY" or "--switch MANDATORY"
-  #     "--switch[=OPTIONAL]"
-  #     "--switch"
-  #
-  # [Short style switch:]
-  #   Specifies short style switch which takes a mandatory, optional or no
-  #   argument. It's a string of the following form:
-  #     "-xMANDATORY"
-  #     "-x[OPTIONAL]"
-  #     "-x"
-  #   There is also a special form which matches character range (not full
-  #   set of regular expression):
-  #     "-[a-z]MANDATORY"
-  #     "-[a-z][OPTIONAL]"
-  #     "-[a-z]"
-  #
-  # [Argument style and description:]
-  #   Instead of specifying mandatory or optional arguments directly in the
-  #   switch parameter, this separate parameter can be used.
-  #     "=MANDATORY"
-  #     "=[OPTIONAL]"
-  #
-  # [Description:]
-  #   Description string for the option.
-  #     "Run verbosely"
-  #
-  # [Handler:]
-  #   Handler for the parsed argument value. Either give a block or pass a
-  #   Proc or Method as an argument.
+
+  SPLAT_PROC = proc {|*a| a.length <= 1 ? a.first : a} # :nodoc:
+
+  # :call-seq:
+  #   make_switch(params, block = nil)
+  #
+  # :include: ../doc/optparse/creates_option.rdoc
   #
   def make_switch(opts, block = nil)
     short, long, nolong, style, pattern, conv, not_pattern, not_conv, not_style = [], [], []
@@ -1156,6 +1477,8 @@ XXX
     default_pattern = nil
     klass = nil
     q, a = nil
+    has_arg = false
+    values = nil
 
     opts.each do |o|
       # argument class
@@ -1169,7 +1492,7 @@ XXX
       end
 
       # directly specified pattern(any object possible to match)
-      if (!(String === o || Symbol === o)) and o.respond_to?(:match)
+      if !Completion.completable?(o) and o.respond_to?(:match)
         pattern = notwice(o, pattern, 'pattern')
         if pattern.respond_to?(:convert)
           conv = pattern.method(:convert).to_proc
@@ -1183,7 +1506,12 @@ XXX
       case o
       when Proc, Method
         block = notwice(o, block, 'block')
-      when Array, Hash
+      when Array, Hash, Set
+        if Array === o
+          o, v = o.partition {|v,| Completion.completable?(v)}
+          values = notwice(v, values, 'values') unless v.empty?
+          next if o.empty?
+        end
         case pattern
         when CompletingHash
         when nil
@@ -1193,11 +1521,13 @@ XXX
           raise ArgumentError, "argument pattern given twice"
         end
         o.each {|pat, *v| pattern[pat] = v.fetch(0) {pat}}
+      when Range
+        values = notwice(o, values, 'values')
       when Module
         raise ArgumentError, "unsupported argument type: #{o}", ParseError.filter_backtrace(caller(4))
       when *ArgumentStyle.keys
         style = notwice(ArgumentStyle[o], style, 'style')
-      when /^--no-([^\[\]=\s]*)(.+)?/
+      when /\A--no-([^\[\]=\s]*)(.+)?/
         q, a = $1, $2
         o = notwice(a ? Object : TrueClass, klass, 'type')
         not_pattern, not_conv = search(:atype, o) unless not_style
@@ -1205,9 +1535,10 @@ XXX
         default_style = Switch::NoArgument
         default_pattern, conv = search(:atype, FalseClass) unless default_pattern
         ldesc << "--no-#{q}"
-        long << 'no-' + (q = q.downcase)
+        (q = q.downcase).tr!('_', '-')
+        long << "no-#{q}"
         nolong << q
-      when /^--\[no-\]([^\[\]=\s]*)(.+)?/
+      when /\A--\[no-\]([^\[\]=\s]*)(.+)?/
         q, a = $1, $2
         o = notwice(a ? Object : TrueClass, klass, 'type')
         if a
@@ -1215,11 +1546,12 @@ XXX
           default_pattern, conv = search(:atype, o) unless default_pattern
         end
         ldesc << "--[no-]#{q}"
-        long << (o = q.downcase)
+        (o = q.downcase).tr!('_', '-')
+        long << o
         not_pattern, not_conv = search(:atype, FalseClass) unless not_style
         not_style = Switch::NoArgument
-        nolong << 'no-' + o
-      when /^--([^\[\]=\s]*)(.+)?/
+        nolong << "no-#{o}"
+      when /\A--([^\[\]=\s]*)(.+)?/
         q, a = $1, $2
         if a
           o = notwice(NilClass, klass, 'type')
@@ -1227,17 +1559,20 @@ XXX
           default_pattern, conv = search(:atype, o) unless default_pattern
         end
         ldesc << "--#{q}"
-        long << (o = q.downcase)
-      when /^-(\[\^?\]?(?:[^\\\]]|\\.)*\])(.+)?/
+        (o = q.downcase).tr!('_', '-')
+        long << o
+      when /\A-(\[\^?\]?(?:[^\\\]]|\\.)*\])(.+)?/
         q, a = $1, $2
         o = notwice(Object, klass, 'type')
         if a
           default_style = default_style.guess(arg = a)
           default_pattern, conv = search(:atype, o) unless default_pattern
+        else
+          has_arg = true
         end
         sdesc << "-#{q}"
         short << Regexp.new(q)
-      when /^-(.)(.+)?/
+      when /\A-(.)(.+)?/
         q, a = $1, $2
         if a
           o = notwice(NilClass, klass, 'type')
@@ -1246,18 +1581,27 @@ XXX
         end
         sdesc << "-#{q}"
         short << q
-      when /^=/
+      when /\A=/
         style = notwice(default_style.guess(arg = o), style, 'style')
         default_pattern, conv = search(:atype, Object) unless default_pattern
       else
-        desc.push(o)
+        desc.push(o) if o && !o.empty?
       end
     end
 
     default_pattern, conv = search(:atype, default_style.pattern) unless default_pattern
+    if Range === values and klass
+      unless (!values.begin or klass === values.begin) and
+            (!values.end or klass === values.end)
+        raise ArgumentError, "range does not match class"
+      end
+    end
     if !(short.empty? and long.empty?)
+      if has_arg and default_style == Switch::NoArgument
+        default_style = Switch::RequiredArgument
+      end
       s = (style || default_style).new(pattern || default_pattern,
-                                       conv, sdesc, ldesc, arg, desc, block)
+                                       conv, sdesc, ldesc, arg, desc, block, values)
     elsif !block
       if style or pattern
         raise ArgumentError, "no switch given", ParseError.filter_backtrace(caller)
@@ -1266,21 +1610,33 @@ XXX
     else
       short << pattern
       s = (style || default_style).new(pattern,
-                                       conv, nil, nil, arg, desc, block)
+                                       conv, nil, nil, arg, desc, block, values)
     end
     return s, short, long,
       (not_style.new(not_pattern, not_conv, sdesc, ldesc, nil, desc, block) if not_style),
       nolong
   end
 
+  # ----
+  # Option definition phase methods
+  #
+  # These methods are used to define options, or to construct an
+  # OptionParser instance in other words.
+
+  # :call-seq:
+  #   define(*params, &block)
+  #
+  # :include: ../doc/optparse/creates_option.rdoc
+  #
   def define(*opts, &block)
     top.append(*(sw = make_switch(opts, block)))
     sw[0]
   end
 
+  # :call-seq:
+  #   on(*params, &block)
   #
-  # Add option switch and handler. See #make_switch for an explanation of
-  # parameters.
+  # :include: ../doc/optparse/creates_option.rdoc
   #
   def on(*opts, &block)
     define(*opts, &block)
@@ -1288,13 +1644,22 @@ XXX
   end
   alias def_option define
 
+  # :call-seq:
+  #   define_head(*params, &block)
+  #
+  # :include: ../doc/optparse/creates_option.rdoc
+  #
   def define_head(*opts, &block)
     top.prepend(*(sw = make_switch(opts, block)))
     sw[0]
   end
 
+  # :call-seq:
+  #   on_head(*params, &block)
   #
-  # Add option switch like with #on, but at head of summary.
+  # :include: ../doc/optparse/creates_option.rdoc
+  #
+  # The new option is added at the head of the summary.
   #
   def on_head(*opts, &block)
     define_head(*opts, &block)
@@ -1302,13 +1667,23 @@ XXX
   end
   alias def_head_option define_head
 
+  # :call-seq:
+  #   define_tail(*params, &block)
+  #
+  # :include: ../doc/optparse/creates_option.rdoc
+  #
   def define_tail(*opts, &block)
     base.append(*(sw = make_switch(opts, block)))
     sw[0]
   end
 
   #
-  # Add option switch like with #on, but at tail of summary.
+  # :call-seq:
+  #   on_tail(*params, &block)
+  #
+  # :include: ../doc/optparse/creates_option.rdoc
+  #
+  # The new option is added at the tail of the summary.
   #
   def on_tail(*opts, &block)
     define_tail(*opts, &block)
@@ -1323,25 +1698,37 @@ XXX
     top.append(string, nil, nil)
   end
 
+  # ----
+  # Arguments parse phase methods
+  #
+  # These methods parse +argv+, convert, and store the results by
+  # calling handlers.  As these methods do not modify +self+, +self+
+  # can be frozen.
+
   #
   # Parses command line arguments +argv+ in order. When a block is given,
-  # each non-option argument is yielded.
+  # each non-option argument is yielded. When optional +into+ keyword
+  # argument is provided, the parsed option values are stored there via
+  # <code>[]=</code> method (so it can be Hash, or OpenStruct, or other
+  # similar object).
   #
   # Returns the rest of +argv+ left unparsed.
   #
-  def order(*argv, &block)
+  def order(*argv, **keywords, &nonopt)
     argv = argv[0].dup if argv.size == 1 and Array === argv[0]
-    order!(argv, &block)
+    order!(argv, **keywords, &nonopt)
   end
 
   #
   # Same as #order, but removes switches destructively.
+  # Non-option arguments remain in +argv+.
   #
-  def order!(argv = default_argv, &nonopt)
-    parse_in_order(argv, &nonopt)
+  def order!(argv = default_argv, into: nil, **keywords, &nonopt)
+    setter = ->(name, val) {into[name.to_sym] = val} if into
+    parse_in_order(argv, setter, **keywords, &nonopt)
   end
 
-  def parse_in_order(argv = default_argv, setter = nil, &nonopt)  # :nodoc:
+  private def parse_in_order(argv = default_argv, setter = nil, exact: require_exact, **, &nonopt)  # :nodoc:
     opt, arg, val, rest = nil
     nonopt ||= proc {|a| throw :terminate, a}
     argv.unshift(arg) if arg = catch(:terminate) {
@@ -1350,31 +1737,44 @@ XXX
         # long option
         when /\A--([^=]*)(?:=(.*))?/m
           opt, rest = $1, $2
+          opt.tr!('_', '-')
           begin
-            sw, = complete(:long, opt, true)
+            if exact
+              sw, = search(:long, opt)
+            else
+              sw, = complete(:long, opt, true)
+            end
           rescue ParseError
+            throw :terminate, arg unless raise_unknown
             raise $!.set_option(arg, true)
+          else
+            unless sw
+              throw :terminate, arg unless raise_unknown
+              raise InvalidOption, arg
+            end
           end
           begin
             opt, cb, val = sw.parse(rest, argv) {|*exc| raise(*exc)}
-            val = cb.call(val) if cb
-            setter.call(sw.switch_name, val) if setter
+            val = callback!(cb, 1, val) if cb
+            callback!(setter, 2, sw.switch_name, val) if setter
           rescue ParseError
             raise $!.set_option(arg, rest)
           end
 
         # short option
         when /\A-(.)((=).*|.+)?/m
-          opt, has_arg, eq, val, rest = $1, $3, $3, $2, $2
+          eq, rest, opt = $3, $2, $1
+          has_arg, val = eq, rest
           begin
             sw, = search(:short, opt)
             unless sw
               begin
                 sw, = complete(:short, opt)
                 # short option matched.
-                val = arg.sub(/\A-/, '')
+                val = arg.delete_prefix('-')
                 has_arg = true
               rescue InvalidOption
+                raise if exact
                 # if no short options match, try completion with long
                 # options.
                 sw, = complete(:long, opt)
@@ -1382,14 +1782,20 @@ XXX
               end
             end
           rescue ParseError
+            throw :terminate, arg unless raise_unknown
             raise $!.set_option(arg, true)
           end
           begin
             opt, cb, val = sw.parse(val, argv) {|*exc| raise(*exc) if eq}
+          rescue ParseError
+            raise $!.set_option(arg, arg.length > 2)
+          else
             raise InvalidOption, arg if has_arg and !eq and arg == "-#{opt}"
+          end
+          begin
             argv.unshift(opt) if opt and (!rest or (opt = opt.sub(/\A-*/, '-')) != '-')
-            val = cb.call(val) if cb
-            setter.call(sw.switch_name, val) if setter
+            val = callback!(cb, 1, val) if cb
+            callback!(setter, 2, sw.switch_name, val) if setter
           rescue ParseError
             raise $!.set_option(arg, arg.length > 2)
           end
@@ -1413,23 +1819,38 @@ XXX
 
     argv
   end
-  private :parse_in_order
+
+  # Calls callback with _val_.
+  private def callback!(cb, max_arity, *args) # :nodoc:
+    args.compact!
+
+    if (size = args.size) < max_arity and cb.to_proc.lambda?
+      (arity = cb.arity) < 0 and arity = (1-arity)
+      arity = max_arity if arity > max_arity
+      args[arity - 1] = nil if arity > size
+    end
+    cb.call(*args)
+  end
 
   #
   # Parses command line arguments +argv+ in permutation mode and returns
-  # list of non-option arguments.
+  # list of non-option arguments. When optional +into+ keyword
+  # argument is provided, the parsed option values are stored there via
+  # <code>[]=</code> method (so it can be Hash, or OpenStruct, or other
+  # similar object).
   #
-  def permute(*argv)
+  def permute(*argv, **keywords)
     argv = argv[0].dup if argv.size == 1 and Array === argv[0]
-    permute!(argv)
+    permute!(argv, **keywords)
   end
 
   #
   # Same as #permute, but removes switches destructively.
+  # Non-option arguments remain in +argv+.
   #
-  def permute!(argv = default_argv)
+  def permute!(argv = default_argv, **keywords)
     nonopts = []
-    order!(argv, &nonopts.method(:<<))
+    order!(argv, **keywords) {|nonopt| nonopts << nonopt}
     argv[0, 0] = nonopts
     argv
   end
@@ -1437,126 +1858,159 @@ XXX
   #
   # Parses command line arguments +argv+ in order when environment variable
   # POSIXLY_CORRECT is set, and in permutation mode otherwise.
+  # When optional +into+ keyword argument is provided, the parsed option
+  # values are stored there via <code>[]=</code> method (so it can be Hash,
+  # or OpenStruct, or other similar object).
   #
-  def parse(*argv)
+  def parse(*argv, **keywords)
     argv = argv[0].dup if argv.size == 1 and Array === argv[0]
-    parse!(argv)
+    parse!(argv, **keywords)
   end
 
   #
   # Same as #parse, but removes switches destructively.
+  # Non-option arguments remain in +argv+.
   #
-  def parse!(argv = default_argv)
+  def parse!(argv = default_argv, **keywords)
     if ENV.include?('POSIXLY_CORRECT')
-      order!(argv)
+      order!(argv, **keywords)
     else
-      permute!(argv)
+      permute!(argv, **keywords)
     end
   end
 
   #
   # Wrapper method for getopts.rb.
   #
-  #   params = ARGV.getopts("ab:", "foo", "bar:")
+  #   params = ARGV.getopts("ab:", "foo", "bar:", "zot:Z;zot option")
+  #   # params["a"] = true   # -a
+  #   # params["b"] = "1"    # -b1
+  #   # params["foo"] = "1"  # --foo
+  #   # params["bar"] = "x"  # --bar x
+  #   # params["zot"] = "z"  # --zot Z
+  #
+  # Option +symbolize_names+ (boolean) specifies whether returned Hash keys should be Symbols; defaults to +false+ (use Strings).
+  #
+  #   params = ARGV.getopts("ab:", "foo", "bar:", "zot:Z;zot option", symbolize_names: true)
   #   # params[:a] = true   # -a
   #   # params[:b] = "1"    # -b1
   #   # params[:foo] = "1"  # --foo
   #   # params[:bar] = "x"  # --bar x
+  #   # params[:zot] = "z"  # --zot Z
   #
-  def getopts(*args)
+  def getopts(*args, symbolize_names: false, **keywords)
     argv = Array === args.first ? args.shift : default_argv
     single_options, *long_options = *args
 
     result = {}
+    setter = (symbolize_names ?
+                ->(name, val) {result[name.to_sym] = val}
+              : ->(name, val) {result[name] = val})
 
     single_options.scan(/(.)(:)?/) do |opt, val|
       if val
-        result[opt] = nil
+        setter[opt, nil]
         define("-#{opt} VAL")
       else
-        result[opt] = false
+        setter[opt, false]
         define("-#{opt}")
       end
     end if single_options
 
     long_options.each do |arg|
+      arg, desc = arg.split(';', 2)
       opt, val = arg.split(':', 2)
       if val
-        result[opt] = val.empty? ? nil : val
-        define("--#{opt} VAL")
+        setter[opt, (val unless val.empty?)]
+        define("--#{opt}=#{result[opt] || "VAL"}", *[desc].compact)
       else
-        result[opt] = false
-        define("--#{opt}")
+        setter[opt, false]
+        define("--#{opt}", *[desc].compact)
       end
     end
 
-    parse_in_order(argv, result.method(:[]=))
+    parse_in_order(argv, setter, **keywords)
     result
   end
 
   #
   # See #getopts.
   #
-  def self.getopts(*args)
-    new.getopts(*args)
+  def self.getopts(*args, symbolize_names: false)
+    new.getopts(*args, symbolize_names: symbolize_names)
   end
 
   #
   # Traverses @stack, sending each element method +id+ with +args+ and
   # +block+.
   #
-  def visit(id, *args, &block)
+  private def visit(id, *args, &block) # :nodoc:
     @stack.reverse_each do |el|
-      el.send(id, *args, &block)
+      el.__send__(id, *args, &block)
     end
     nil
   end
-  private :visit
 
   #
   # Searches +key+ in @stack for +id+ hash and returns or yields the result.
   #
-  def search(id, key)
+  private def search(id, key) # :nodoc:
     block_given = block_given?
     visit(:search, id, key) do |k|
       return block_given ? yield(k) : k
     end
   end
-  private :search
 
   #
   # Completes shortened long style option switch and returns pair of
   # canonical switch and switch descriptor OptionParser::Switch.
   #
-  # +id+::    Searching table.
+  # +typ+::   Searching table.
   # +opt+::   Searching key.
   # +icase+:: Search case insensitive if true.
   # +pat+::   Optional pattern for completion.
   #
-  def complete(typ, opt, icase = false, *pat)
+  private def complete(typ, opt, icase = false, *pat) # :nodoc:
     if pat.empty?
       search(typ, opt) {|sw| return [sw, opt]} # exact match or...
     end
-    raise AmbiguousOption, catch(:ambiguous) {
+    ambiguous = catch(:ambiguous) {
       visit(:complete, typ, opt, icase, *pat) {|o, *sw| return sw}
-      raise InvalidOption, opt
     }
+    exc = ambiguous ? AmbiguousOption : InvalidOption
+    raise exc.new(opt, additional: proc {|o| additional_message(typ, o)})
+  end
+
+  #
+  # Returns additional info.
+  #
+  def additional_message(typ, opt)
+    return unless typ and opt and defined?(DidYouMean::SpellChecker)
+    all_candidates = []
+    visit(:get_candidates, typ) do |candidates|
+      all_candidates.concat(candidates)
+    end
+    all_candidates.select! {|cand| cand.is_a?(String) }
+    checker = DidYouMean::SpellChecker.new(dictionary: all_candidates)
+    DidYouMean.formatter.message_for(all_candidates & checker.correct(opt))
   end
-  private :complete
 
+  #
+  # Return candidates for +word+.
+  #
   def candidate(word)
     list = []
     case word
+    when '-'
+      long = short = true
     when /\A--/
       word, arg = word.split(/=/, 2)
       argpat = Completion.regexp(arg, false) if arg and !arg.empty?
       long = true
-    when /\A-(!-)/
-      short = true
     when /\A-/
-      long = short = true
+      short = true
     end
-    pat = Completion.regexp(word, true)
+    pat = Completion.regexp(word, long)
     visit(:each_option) do |opt|
       next unless Switch === opt
       opts = (long ? opt.long : []) + (short ? opt.short : [])
@@ -1579,16 +2033,40 @@ XXX
   # is not present. Returns whether successfully loaded.
   #
   # +filename+ defaults to basename of the program without suffix in a
-  # directory ~/.options.
-  #
-  def load(filename = nil)
-    begin
-      filename ||= File.expand_path(File.basename($0, '.*'), '~/.options')
-    rescue
-      return false
+  # directory ~/.options, then the basename with '.options' suffix
+  # under XDG and Haiku standard places.
+  #
+  # The optional +into+ keyword argument works exactly like that accepted in
+  # method #parse.
+  #
+  def load(filename = nil, **keywords)
+    unless filename
+      basename = File.basename($0, '.*')
+      return true if load(File.expand_path("~/.options/#{basename}"), **keywords) rescue nil
+      basename << ".options"
+      if !(xdg = ENV['XDG_CONFIG_HOME']) or xdg.empty?
+        # https://specifications.freedesktop.org/basedir-spec/latest/#variables
+        #
+        # If $XDG_CONFIG_HOME is either not set or empty, a default
+        # equal to $HOME/.config should be used.
+        xdg = ['~/.config', true]
+      end
+      return [
+        xdg,
+
+        *ENV['XDG_CONFIG_DIRS']&.split(File::PATH_SEPARATOR),
+
+        # Haiku
+        ['~/config/settings', true],
+      ].any? {|dir, expand|
+        next if !dir or dir.empty?
+        filename = File.join(dir, basename)
+        filename = File.expand_path(filename) if expand
+        load(filename, **keywords) rescue nil
+      }
     end
     begin
-      parse(*IO.readlines(filename).each {|s| s.chomp!})
+      parse(*File.readlines(filename, chomp: true), **keywords)
       true
     rescue Errno::ENOENT, Errno::ENOTDIR
       false
@@ -1601,10 +2079,10 @@ XXX
   #
   # +env+ defaults to the basename of the program.
   #
-  def environment(env = File.basename($0, '.*'))
+  def environment(env = File.basename($0, '.*'), **keywords)
     env = ENV[env] || ENV[env.upcase] or return
     require 'shellwords'
-    parse(*Shellwords.shellwords(env))
+    parse(*Shellwords.shellwords(env), **keywords)
   end
 
   #
@@ -1645,7 +2123,7 @@ XXX
   #
   # Float number format, and converts to Float.
   #
-  float = "(?:#{decimal}(?:\\.(?:#{decimal})?)?|\\.#{decimal})(?:E[-+]?#{decimal})?"
+  float = "(?:#{decimal}(?=(.)?)(?:\\.(?:#{decimal})?)?|\\.#{decimal})(?:E[-+]?#{decimal})?"
   floatpat = %r"\A[-+]?#{float}\z"io
   accept(Float, floatpat) {|s,| s.to_f if s}
 
@@ -1654,11 +2132,13 @@ XXX
   # for float format, and Rational for rational format.
   #
   real = "[-+]?(?:#{octal}|#{float})"
-  accept(Numeric, /\A(#{real})(?:\/(#{real}))?\z/io) {|s, d, n|
+  accept(Numeric, /\A(#{real})(?:\/(#{real}))?\z/io) {|s, d, f, n,|
     if n
       Rational(d, n)
-    elsif s
-      eval(s)
+    elsif f
+      Float(s)
+    else
+      Integer(s)
     end
   }
 
@@ -1668,7 +2148,7 @@ XXX
   DecimalInteger = /\A[-+]?#{decimal}\z/io
   accept(DecimalInteger, DecimalInteger) {|s,|
     begin
-      Integer(s)
+      Integer(s, 10)
     rescue ArgumentError
       raise OptionParser::InvalidArgument, s
     end if s
@@ -1692,10 +2172,14 @@ XXX
   # integer format, Float for float format.
   #
   DecimalNumeric = floatpat     # decimal integer is allowed as float also.
-  accept(DecimalNumeric, floatpat) {|s,|
+  accept(DecimalNumeric, floatpat) {|s, f|
     begin
-      eval(s)
-    rescue SyntaxError
+      if f
+        Float(s)
+      else
+        Integer(s)
+      end
+    rescue ArgumentError
       raise OptionParser::InvalidArgument, s
     end if s
   }
@@ -1718,7 +2202,7 @@ XXX
   #
   # List of strings separated by ",".
   #
-  accept(Array) do |s,|
+  accept(Array) do |s, |
     if s
       s = s.split(',').collect {|ss| ss unless ss.empty?}
     end
@@ -1734,10 +2218,23 @@ XXX
       f |= Regexp::IGNORECASE if /i/ =~ o
       f |= Regexp::MULTILINE if /m/ =~ o
       f |= Regexp::EXTENDED if /x/ =~ o
-      k = o.delete("imx")
-      k = nil if k.empty?
+      case o = o.delete("imx")
+      when ""
+      when "u"
+        s = s.encode(Encoding::UTF_8)
+      when "e"
+        s = s.encode(Encoding::EUC_JP)
+      when "s"
+        s = s.encode(Encoding::SJIS)
+      when "n"
+        f |= Regexp::NOENCODING
+      else
+        raise OptionParser::InvalidArgument, "unknown regexp option - #{o}"
+      end
+    else
+      s ||= all
     end
-    Regexp.new(s || all, f, k)
+    Regexp.new(s, f)
   end
 
   #
@@ -1749,15 +2246,19 @@ XXX
   #
   class ParseError < RuntimeError
     # Reason which caused the error.
-    Reason = 'parse error'.freeze
+    Reason = 'parse error'
 
-    def initialize(*args)
+    # :nodoc:
+    def initialize(*args, additional: nil)
+      @additional = additional
+      @arg0, = args
       @args = args
       @reason = nil
     end
 
     attr_reader :args
     attr_writer :reason
+    attr_accessor :additional
 
     #
     # Pushes back erred argument(s) to +argv+.
@@ -1767,9 +2268,10 @@ XXX
       argv
     end
 
+    DIR = File.join(__dir__, '')
     def self.filter_backtrace(array)
       unless $DEBUG
-        array.delete_if(&%r"\A#{Regexp.quote(__FILE__)}:"o.method(:=~))
+        array.delete_if {|bt| bt.start_with?(DIR)}
       end
       array
     end
@@ -1795,14 +2297,14 @@ XXX
     end
 
     def inspect
-      "#<#{self.class.to_s}: #{args.join(' ')}>"
+      "#<#{self.class}: #{args.join(' ')}>"
     end
 
     #
     # Default stringizing method to emit standard error message.
     #
     def message
-      reason + ': ' + args.join(' ')
+      "#{reason}: #{args.join(' ')}#{additional[@arg0] if additional}"
     end
 
     alias to_s message
@@ -1812,42 +2314,42 @@ XXX
   # Raises when ambiguously completable string is encountered.
   #
   class AmbiguousOption < ParseError
-    const_set(:Reason, 'ambiguous option'.freeze)
+    Reason = 'ambiguous option'    # :nodoc:
   end
 
   #
   # Raises when there is an argument for a switch which takes no argument.
   #
   class NeedlessArgument < ParseError
-    const_set(:Reason, 'needless argument'.freeze)
+    Reason = 'needless argument'    # :nodoc:
   end
 
   #
   # Raises when a switch with mandatory argument has no argument.
   #
   class MissingArgument < ParseError
-    const_set(:Reason, 'missing argument'.freeze)
+    Reason = 'missing argument'    # :nodoc:
   end
 
   #
   # Raises when switch is undefined.
   #
   class InvalidOption < ParseError
-    const_set(:Reason, 'invalid option'.freeze)
+    Reason = 'invalid option'    # :nodoc:
   end
 
   #
   # Raises when the given argument does not match required format.
   #
   class InvalidArgument < ParseError
-    const_set(:Reason, 'invalid argument'.freeze)
+    Reason = 'invalid argument'    # :nodoc:
   end
 
   #
   # Raises when the given argument word can't be completed uniquely.
   #
   class AmbiguousArgument < InvalidArgument
-    const_set(:Reason, 'ambiguous argument'.freeze)
+    Reason = 'ambiguous argument'    # :nodoc:
   end
 
   #
@@ -1898,19 +2400,19 @@ XXX
     # Parses +self+ destructively in order and returns +self+ containing the
     # rest arguments left unparsed.
     #
-    def order!(&blk) options.order!(self, &blk) end
+    def order!(**keywords, &blk) options.order!(self, **keywords, &blk) end
 
     #
     # Parses +self+ destructively in permutation mode and returns +self+
     # containing the rest arguments left unparsed.
     #
-    def permute!() options.permute!(self) end
+    def permute!(**keywords) options.permute!(self, **keywords) end
 
     #
     # Parses +self+ destructively and returns +self+ containing the
     # rest arguments left unparsed.
     #
-    def parse!() options.parse!(self) end
+    def parse!(**keywords) options.parse!(self, **keywords) end
 
     #
     # Substitution of getopts is possible as follows. Also see
@@ -1923,8 +2425,8 @@ XXX
     #   rescue OptionParser::ParseError
     #   end
     #
-    def getopts(*args)
-      options.getopts(self, *args)
+    def getopts(*args, symbolize_names: false, **keywords)
+      options.getopts(self, *args, symbolize_names: symbolize_names, **keywords)
     end
 
     #
@@ -1934,7 +2436,8 @@ XXX
       super
       obj.instance_eval {@optparse = nil}
     end
-    def initialize(*args)
+
+    def initialize(*args)       # :nodoc:
       super
       @optparse = nil
     end
@@ -1945,18 +2448,16 @@ XXX
   # and DecimalNumeric. See Acceptable argument classes (in source code).
   #
   module Acceptables
-    const_set(:DecimalInteger, OptionParser::DecimalInteger)
-    const_set(:OctalInteger, OptionParser::OctalInteger)
-    const_set(:DecimalNumeric, OptionParser::DecimalNumeric)
+    # :stopdoc:
+    DecimalInteger = OptionParser::DecimalInteger
+    OctalInteger = OptionParser::OctalInteger
+    DecimalNumeric = OptionParser::DecimalNumeric
+    # :startdoc:
   end
 end
 
 # ARGV is arguable by OptionParser
 ARGV.extend(OptionParser::Arguable)
 
-if $0 == __FILE__
-  Version = OptionParser::Version
-  ARGV.options {|q|
-    q.parse!.empty? or print "what's #{ARGV.join(' ')}?\n"
-  } or abort(ARGV.options.to_s)
-end
+# An alias for OptionParser.
+OptParse = OptionParser  # :nodoc:
diff --git a/lib/optparse/ac.rb b/lib/optparse/ac.rb
new file mode 100644
index 0000000000..23fc740d10
--- /dev/null
+++ b/lib/optparse/ac.rb
@@ -0,0 +1,70 @@
+# frozen_string_literal: false
+require_relative '../optparse'
+
+#
+# autoconf-like options.
+#
+class OptionParser::AC < OptionParser
+  # :stopdoc:
+  private
+
+  def _check_ac_args(name, block)
+    unless /\A\w[-\w]*\z/ =~ name
+      raise ArgumentError, name
+    end
+    unless block
+      raise ArgumentError, "no block given", ParseError.filter_backtrace(caller)
+    end
+  end
+
+  ARG_CONV = proc {|val| val.nil? ? true : val}
+  private_constant :ARG_CONV
+
+  def _ac_arg_enable(prefix, name, help_string, block)
+    _check_ac_args(name, block)
+
+    sdesc = []
+    ldesc = ["--#{prefix}-#{name}"]
+    desc = [help_string]
+    q = name.downcase
+    ac_block = proc {|val| block.call(ARG_CONV.call(val))}
+    enable = Switch::PlacedArgument.new(nil, ARG_CONV, sdesc, ldesc, nil, desc, ac_block)
+    disable = Switch::NoArgument.new(nil, proc {false}, sdesc, ldesc, nil, desc, ac_block)
+    top.append(enable, [], ["enable-" + q], disable, ['disable-' + q])
+    enable
+  end
+
+  # :startdoc:
+
+  public
+
+  # Define <tt>--enable</tt> / <tt>--disable</tt> style option
+  #
+  # Appears as <tt>--enable-<i>name</i></tt> in help message.
+  def ac_arg_enable(name, help_string, &block)
+    _ac_arg_enable("enable", name, help_string, block)
+  end
+
+  # Define <tt>--enable</tt> / <tt>--disable</tt> style option
+  #
+  # Appears as <tt>--disable-<i>name</i></tt> in help message.
+  def ac_arg_disable(name, help_string, &block)
+    _ac_arg_enable("disable", name, help_string, block)
+  end
+
+  # Define <tt>--with</tt> / <tt>--without</tt> style option
+  #
+  # Appears as <tt>--with-<i>name</i></tt> in help message.
+  def ac_arg_with(name, help_string, &block)
+    _check_ac_args(name, block)
+
+    sdesc = []
+    ldesc = ["--with-#{name}"]
+    desc = [help_string]
+    q = name.downcase
+    with = Switch::PlacedArgument.new(*search(:atype, String), sdesc, ldesc, nil, desc, block)
+    without = Switch::NoArgument.new(nil, proc {}, sdesc, ldesc, nil, desc, block)
+    top.append(with, [], ["with-" + q], without, ['without-' + q])
+    with
+  end
+end
diff --git a/lib/optparse/date.rb b/lib/optparse/date.rb
index d680559f37..7bbf12b77f 100644
--- a/lib/optparse/date.rb
+++ b/lib/optparse/date.rb
@@ -1,4 +1,5 @@
-require 'optparse'
+# frozen_string_literal: false
+require_relative '../optparse'
 require 'date'
 
 OptionParser.accept(DateTime) do |s,|
diff --git a/lib/optparse/kwargs.rb b/lib/optparse/kwargs.rb
new file mode 100644
index 0000000000..59a2f61544
--- /dev/null
+++ b/lib/optparse/kwargs.rb
@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+require_relative '../optparse'
+
+class OptionParser
+  # :call-seq:
+  #   define_by_keywords(options, method, **params)
+  #
+  # :include: ../../doc/optparse/creates_option.rdoc
+  #
+  # Defines options which set in to _options_ for keyword parameters
+  # of _method_.
+  #
+  # Parameters for each keywords are given as elements of _params_.
+  #
+  def define_by_keywords(options, method, **params)
+    method.parameters.each do |type, name|
+      case type
+      when :key, :keyreq
+        op, cl = *(type == :key ? %w"[ ]" : ["", ""])
+        define("--#{name}=#{op}#{name.upcase}#{cl}", *params[name]) do |o|
+          options[name] = o
+        end
+      end
+    end
+    options
+  end
+end
diff --git a/lib/optparse/optparse.gemspec b/lib/optparse/optparse.gemspec
new file mode 100644
index 0000000000..885b0ec380
--- /dev/null
+++ b/lib/optparse/optparse.gemspec
@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+name = File.basename(__FILE__, ".gemspec")
+version = ["lib", Array.new(name.count("-")+1, "..").join("/")].find do |dir|
+  break File.foreach(File.join(__dir__, dir, "#{name.tr('-', '/')}.rb")) do |line|
+    /^\s*VERSION\s*=\s*"(.*)"/ =~ line and break $1
+  end rescue nil
+end
+
+Gem::Specification.new do |spec|
+  spec.name          = name
+  spec.version       = version
+  spec.authors       = ["Nobu Nakada"]
+  spec.email         = ["nobu@ruby-lang.org"]
+
+  spec.summary       = %q{OptionParser is a class for command-line option analysis.}
+  spec.description   = File.open(File.join(__dir__, "README.md")) do |readme|
+    readme.gets("") # heading
+    readme.gets("").chomp
+  end rescue spec.summary
+  spec.homepage      = "https://github.com/ruby/optparse"
+  spec.required_ruby_version = Gem::Requirement.new(">= 2.5.0")
+  spec.licenses      = ["Ruby", "BSD-2-Clause"]
+
+  spec.metadata["homepage_uri"] = spec.homepage
+  spec.metadata["source_code_uri"] = spec.homepage
+
+  dir, gemspec = File.split(__FILE__)
+  excludes = %W[#{gemspec} rakelib test/ Gemfile Rakefile .git* .editor*].map {|n| ":^"+n}
+  spec.files = IO.popen(%w[git ls-files -z --] + excludes, chdir: dir, &:read).split("\x0")
+  spec.bindir        = "exe"
+  spec.executables   = []
+  spec.require_paths = ["lib"]
+end
diff --git a/lib/optparse/shellwords.rb b/lib/optparse/shellwords.rb
index 0422d7c887..4feb1993d9 100644
--- a/lib/optparse/shellwords.rb
+++ b/lib/optparse/shellwords.rb
@@ -1,6 +1,7 @@
+# frozen_string_literal: false
 # -*- ruby -*-
 
 require 'shellwords'
-require 'optparse'
+require_relative '../optparse'
 
 OptionParser.accept(Shellwords) {|s,| Shellwords.shellwords(s)}
diff --git a/lib/optparse/time.rb b/lib/optparse/time.rb
index 402cadcf16..0ce651f6f6 100644
--- a/lib/optparse/time.rb
+++ b/lib/optparse/time.rb
@@ -1,4 +1,5 @@
-require 'optparse'
+# frozen_string_literal: false
+require_relative '../optparse'
 require 'time'
 
 OptionParser.accept(Time) do |s,|
diff --git a/lib/optparse/uri.rb b/lib/optparse/uri.rb
index 024dc69eac..31d10593b1 100644
--- a/lib/optparse/uri.rb
+++ b/lib/optparse/uri.rb
@@ -1,6 +1,7 @@
+# frozen_string_literal: false
 # -*- ruby -*-
 
-require 'optparse'
+require_relative '../optparse'
 require 'uri'
 
 OptionParser.accept(URI) {|s,| URI.parse(s) if s}
diff --git a/lib/optparse/version.rb b/lib/optparse/version.rb
index 76ed564287..b5ed695146 100644
--- a/lib/optparse/version.rb
+++ b/lib/optparse/version.rb
@@ -1,6 +1,12 @@
+# frozen_string_literal: false
 # OptionParser internal utility
 
 class << OptionParser
+  #
+  # Shows version string in packages if Version is defined.
+  #
+  # +pkgs+:: package list
+  #
   def show_version(*pkgs)
     progname = ARGV.options.program_name
     result = false
@@ -46,12 +52,14 @@ class << OptionParser
     result
   end
 
+  # :stopdoc:
+
   def each_const(path, base = ::Object)
     path.split(/::|\//).inject(base) do |klass, name|
       raise NameError, path unless Module === klass
       klass.constants.grep(/#{name}/i) do |c|
         klass.const_defined?(c) or next
-        c = klass.const_get(c)
+        klass.const_get(c)
       end
     end
   end
@@ -67,4 +75,6 @@ class << OptionParser
       end
     end
   end
+
+  # :startdoc:
 end
diff --git a/lib/ostruct.rb b/lib/ostruct.rb
deleted file mode 100644
index a4c0d55d09..0000000000
--- a/lib/ostruct.rb
+++ /dev/null
@@ -1,236 +0,0 @@
-#
-# = ostruct.rb: OpenStruct implementation
-#
-# Author:: Yukihiro Matsumoto
-# Documentation:: Gavin Sinclair
-#
-# OpenStruct allows the creation of data objects with arbitrary attributes.
-# See OpenStruct for an example.
-#
-
-#
-# An OpenStruct is a data structure, similar to a Hash, that allows the
-# definition of arbitrary attributes with their accompanying values. This is
-# accomplished by using Ruby's metaprogramming to define methods on the class
-# itself.
-#
-# == Examples:
-#
-#   require 'ostruct'
-#
-#   person = OpenStruct.new
-#   person.name    = "John Smith"
-#   person.age     = 70
-#   person.pension = 300
-#
-#   puts person.name     # -> "John Smith"
-#   puts person.age      # -> 70
-#   puts person.address  # -> nil
-#
-# An OpenStruct employs a Hash internally to store the methods and values and
-# can even be initialized with one:
-#
-#   australia = OpenStruct.new(:country => "Australia", :population => 20_000_000)
-#   p australia   # -> <OpenStruct country="Australia" population=20000000>
-#
-# Hash keys with spaces or characters that would normally not be able to use for
-# method calls (e.g. ()[]*) will not be immediately available on the
-# OpenStruct object as a method for retrieval or assignment, but can be still be
-# reached through the Object#send method.
-#
-#   measurements = OpenStruct.new("length (in inches)" => 24)
-#   measurements.send("length (in inches)")  # -> 24
-#
-#   data_point = OpenStruct.new(:queued? => true)
-#   data_point.queued?                       # -> true
-#   data_point.send("queued?=",false)
-#   data_point.queued?                       # -> false
-#
-# Removing the presence of a method requires the execution the delete_field
-# method as setting the property value to +nil+ will not remove the method.
-#
-#   first_pet = OpenStruct.new(:name => 'Rowdy', :owner => 'John Smith')
-#   first_pet.owner = nil
-#   second_pet = OpenStruct.new(:name => 'Rowdy')
-#
-#   first_pet == second_pet   # -> false
-#
-#   first_pet.delete_field(:owner)
-#   first_pet == second_pet   # -> true
-#
-#
-# == Implementation:
-#
-# An OpenStruct utilizes Ruby's method lookup structure to and find and define
-# the necessary methods for properties. This is accomplished through the method
-# method_missing and define_method.
-#
-# This should be a consideration if there is a concern about the performance of
-# the objects that are created, as there is much more overhead in the setting
-# of these properties compared to using a Hash or a Struct.
-#
-class OpenStruct
-  #
-  # Creates a new OpenStruct object.  By default, the resulting OpenStruct
-  # object will have no attributes.
-  #
-  # The optional +hash+, if given, will generate attributes and values.
-  # For example:
-  #
-  #   require 'ostruct'
-  #   hash = { "country" => "Australia", :population => 20_000_000 }
-  #   data = OpenStruct.new(hash)
-  #
-  #   p data        # -> <OpenStruct country="Australia" population=20000000>
-  #
-  def initialize(hash=nil)
-    @table = {}
-    if hash
-      for k,v in hash
-        @table[k.to_sym] = v
-        new_ostruct_member(k)
-      end
-    end
-  end
-
-  # Duplicate an OpenStruct object members.
-  def initialize_copy(orig)
-    super
-    @table = @table.dup
-  end
-
-  #
-  # Provides marshalling support for use by the Marshal library. Returning the
-  # underlying Hash table that contains the functions defined as the keys and
-  # the values assigned to them.
-  #
-  #    require 'ostruct'
-  #
-  #    person = OpenStruct.new
-  #    person.name = 'John Smith'
-  #    person.age  = 70
-  #
-  #    person.marshal_dump # => { :name => 'John Smith', :age => 70 }
-  #
-  def marshal_dump
-    @table
-  end
-
-  #
-  # Provides marshalling support for use by the Marshal library. Accepting
-  # a Hash of keys and values which will be used to populate the internal table
-  #
-  #    require 'ostruct'
-  #
-  #    event = OpenStruct.new
-  #    hash = { 'time' => Time.now, 'title' => 'Birthday Party' }
-  #    event.marshal_load(hash)
-  #    event.title # => 'Birthday Party'
-  #
-  def marshal_load(x)
-    @table = x
-    @table.each_key{|key| new_ostruct_member(key)}
-  end
-
-  #
-  # #modifiable is used internally to check if the OpenStruct is able to be
-  # modified before granting access to the internal Hash table to be modified.
-  #
-  def modifiable
-    begin
-      @modifiable = true
-    rescue
-      raise TypeError, "can't modify frozen #{self.class}", caller(3)
-    end
-    @table
-  end
-  protected :modifiable
-
-  #
-  # new_ostruct_member is used internally to defined properties on the
-  # OpenStruct. It does this by using the metaprogramming function
-  # define_method for both the getter method and the setter method.
-  #
-  def new_ostruct_member(name)
-    name = name.to_sym
-    unless self.respond_to?(name)
-      class << self; self; end.class_eval do
-        define_method(name) { @table[name] }
-        define_method("#{name}=") { |x| modifiable[name] = x }
-      end
-    end
-    name
-  end
-
-  def method_missing(mid, *args) # :nodoc:
-    mname = mid.id2name
-    len = args.length
-    if mname.chomp!('=') && mid != :[]=
-      if len != 1
-        raise ArgumentError, "wrong number of arguments (#{len} for 1)", caller(1)
-      end
-      modifiable[new_ostruct_member(mname)] = args[0]
-    elsif len == 0 && mid != :[]
-      @table[mid]
-    else
-      raise NoMethodError, "undefined method `#{mid}' for #{self}", caller(1)
-    end
-  end
-
-  #
-  # Remove the named field from the object. Returns the value that the field
-  # contained if it was defined.
-  #
-  #   require 'ostruct'
-  #
-  #   person = OpenStruct.new('name' => 'John Smith', 'age' => 70)
-  #
-  #   person.delete_field('name')  # => 'John Smith'
-  #
-  def delete_field(name)
-    sym = name.to_sym
-    singleton_class.__send__(:remove_method, sym, "#{name}=")
-    @table.delete sym
-  end
-
-  InspectKey = :__inspect_key__ # :nodoc:
-
-  #
-  # Returns a string containing a detailed summary of the keys and values.
-  #
-  def inspect
-    str = "#<#{self.class}"
-
-    ids = (Thread.current[InspectKey] ||= [])
-    if ids.include?(object_id)
-      return str << ' ...>'
-    end
-
-    ids << object_id
-    begin
-      first = true
-      for k,v in @table
-        str << "," unless first
-        first = false
-        str << " #{k}=#{v.inspect}"
-      end
-      return str << '>'
-    ensure
-      ids.pop
-    end
-  end
-  alias :to_s :inspect
-
-  attr_reader :table # :nodoc:
-  protected :table
-
-  #
-  # Compares this object and +other+ for equality.  An OpenStruct is equal to
-  # +other+ when +other+ is an OpenStruct and the two object's Hash tables are
-  # equal.
-  #
-  def ==(other)
-    return false unless(other.kind_of?(OpenStruct))
-    return @table == other.table
-  end
-end
diff --git a/lib/pathname.rb b/lib/pathname.rb
new file mode 100644
index 0000000000..0e51e1fdf6
--- /dev/null
+++ b/lib/pathname.rb
@@ -0,0 +1,151 @@
+# frozen_string_literal: true
+#
+# = pathname.rb
+#
+# Object-Oriented Pathname Class
+#
+# Author:: Tanaka Akira <akr@m17n.org>
+# Documentation:: Author and Gavin Sinclair
+#
+# For documentation, see class Pathname.
+#
+class Pathname
+
+  # :markup: markdown
+  #
+  # call-seq:
+  #   Pathname.find(ignore_error: true) -> nil
+  #
+  # With a block given, performs a depth-first traversal of the path in `self`;
+  # calls the block with each found path:
+  #
+  # ```ruby
+  # paths = []
+  # Pathname('lib').find {|path| paths << path }
+  # paths.size  # => 909
+  # paths.take(3)
+  # # =>
+  # # [#<Pathname:lib>,
+  # #  #<Pathname:lib/English.gemspec>,
+  # #  #<Pathname:lib/English.rb>]
+  # ```
+  #
+  # When `self` contains `'.'`, the found paths omit the leading `'./'`:
+  #
+  # ```ruby
+  # paths = []
+  # Dir.chdir('lib') do
+  #   Pathname('.').find {|path| paths << path }
+  # end
+  # paths.take(3)
+  # # # =>
+  # # [#<Pathname:.>,
+  # #  #<Pathname:English.gemspec>,
+  # #  #<Pathname:English.rb>]
+  # ```
+  #
+  # This method calls method Find.find;
+  # therefore method Find.prune may be used in the block:
+  #
+  # ```ruby
+  # files = []
+  # Pathname('.').find do |path|
+  #   Find.prune if File.basename(path) == 'test'
+  #   next unless File.file?(path) && File.extname(path) == '.rb'
+  #   files << path
+  # end
+  # files.size # => 6690
+  # files.take(3)
+  # # # =>
+  # # [#<Pathname:KNOWNBUGS.rb>,
+  # #  #<Pathname:array.rb>,
+  # #  #<Pathname:ast.rb>]
+  # ```
+  #
+  # Raises an exception if the path in `self` cannot be read.
+  #
+  # When keyword argument `ignore_error` is given as `true` (the default),
+  # certain exceptions during traversal are ignored (i.e., silently rescued):
+  # Errno::ENOENT, Errno::EACCES, Errno::ENOTDIR, Errno::ELOOP, Errno::ENAMETOOLONG, Errno::EINVAL;
+  # when given as `false`, no exceptions are rescued.
+  #
+  # Note that these exceptions may be ignored only in `Pathname#find` traversal code;
+  # an exception raised before traversal begins,
+  # or raised while in the block is not ignored.
+  # Each of the calls below raises an Errno::ENOENT exception that is not ignored:
+  #
+  # ```ruby
+  # Pathname('nosuch').find { }
+  # Pathname('lib').find {|entry| raise Errno::ENOENT }
+  # ```
+  #
+  # With no block given, returns a new Enumerator.
+  def find(ignore_error: true) # :yield: pathname
+    return to_enum(__method__, ignore_error: ignore_error) unless block_given?
+    require 'find'
+    if @path == '.'
+      Find.find(@path, ignore_error: ignore_error) {|f| yield self.class.new(f.delete_prefix('./')) }
+    else
+      Find.find(@path, ignore_error: ignore_error) {|f| yield self.class.new(f) }
+    end
+  end
+end
+
+
+class Pathname    # * FileUtils *
+  # Recursively deletes a directory, including all directories beneath it.
+  #
+  # Note that you need to require 'pathname' to use this method.
+  #
+  # See FileUtils.rm_rf
+  def rmtree(noop: nil, verbose: nil, secure: nil)
+    # The name "rmtree" is borrowed from File::Path of Perl.
+    # File::Path provides "mkpath" and "rmtree".
+    require 'fileutils'
+    FileUtils.rm_rf(@path, noop: noop, verbose: verbose, secure: secure)
+    self
+  end
+end
+
+class Pathname    # * tmpdir *
+  # call-seq:
+  #   Pathname.mktmpdir -> new_pathname
+  #   Pathname.mktmpdir {|pathname| ... } -> object
+  #
+  # Creates:
+  #
+  # - A temporary directory via Dir.mktmpdir.
+  # - A \Pathname object that contains the path to that directory.
+  #
+  # With no block given, returns the created pathname;
+  # the caller should delete the created directory when it is no longer needed
+  # (FileUtils.rm_r is a convenient method for the deletion):
+  #
+  #   pathname = Pathname.mktmpdir
+  #   dirpath = pathname.to_s
+  #   Dir.exist?(dirpath) # => true
+  #   # Do something with the directory.
+  #   require 'fileutils'
+  #   FileUtils.rm_r(dirpath)
+  #
+  # With a block given, calls the block with the created pathname;
+  # on block exit, automatically deletes the created directory and all its contents;
+  # returns the block's exit value:
+  #
+  #   pathname = Pathname.mktmpdir do |p|
+  #     # Do something with the directory.
+  #     p
+  #   end
+  #   Dir.exist?(pathname.to_s) # => false
+  def self.mktmpdir
+    require 'tmpdir' unless defined?(Dir.mktmpdir)
+    if block_given?
+      Dir.mktmpdir do |dir|
+        dir = self.new(dir)
+        yield dir
+      end
+    else
+      self.new(Dir.mktmpdir)
+    end
+  end
+end
diff --git a/lib/pp.gemspec b/lib/pp.gemspec
new file mode 100644
index 0000000000..15a3b4dc6c
--- /dev/null
+++ b/lib/pp.gemspec
@@ -0,0 +1,35 @@
+name = File.basename(__FILE__, ".gemspec")
+version = ["lib", Array.new(name.count("-")+1).join("/")].find do |dir|
+  break File.foreach(File.join(__dir__, dir, "#{name.tr('-', '/')}.rb")) do |line|
+    /^\s*VERSION\s*=\s*"(.*)"/ =~ line and break $1
+  end rescue nil
+end
+
+Gem::Specification.new do |spec|
+  spec.name          = name
+  spec.version       = version
+  spec.authors       = ["Tanaka Akira"]
+  spec.email         = ["akr@fsij.org"]
+
+  spec.summary       = %q{Provides a PrettyPrinter for Ruby objects}
+  spec.description   = %q{Provides a PrettyPrinter for Ruby objects}
+  spec.homepage      = "https://github.com/ruby/pp"
+  spec.licenses      = ["Ruby", "BSD-2-Clause"]
+
+  spec.required_ruby_version = Gem::Requirement.new(">= 2.7.0")
+
+  spec.metadata["homepage_uri"] = spec.homepage
+  spec.metadata["source_code_uri"] = spec.homepage
+
+  spec.files         = %w[
+    BSDL
+    COPYING
+    lib/pp.rb
+    pp.gemspec
+  ]
+  spec.bindir        = "exe"
+  spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
+  spec.require_paths = ["lib"]
+
+  spec.add_dependency "prettyprint"
+end
diff --git a/lib/pp.rb b/lib/pp.rb
index 56d726dc7d..5fd29a373a 100644
--- a/lib/pp.rb
+++ b/lib/pp.rb
@@ -1,11 +1,17 @@
-# == Pretty-printer for Ruby objects.
+# frozen_string_literal: true
+
+require 'prettyprint'
+
+##
+# A pretty-printer for Ruby objects.
 #
-# = Which seems better?
+##
+# == What PP Does
 #
-# non-pretty-printed output by #p is:
+# Standard output by #p returns this:
 #   #<PP:0x81fedf0 @genspace=#<Proc:0x81feda0>, @group_queue=#<PrettyPrint::GroupQueue:0x81fed3c @queue=[[#<PrettyPrint::Group:0x81fed78 @breakables=[], @depth=0, @break=false>], []]>, @buffer=[], @newline="\n", @group_stack=[#<PrettyPrint::Group:0x81fed78 @breakables=[], @depth=0, @break=false>], @buffer_width=0, @indent=0, @maxwidth=79, @output_width=2, @output=#<IO:0x8114ee4>>
 #
-# pretty-printed output by #pp is:
+# Pretty-printed output returns this:
 #   #<PP:0x81fedf0
 #    @buffer=[],
 #    @buffer_width=0,
@@ -23,57 +29,72 @@
 #    @output=#<IO:0x8114ee4>,
 #    @output_width=2>
 #
-# I like the latter.  If you do too, this library is for you.
+##
+# == Usage
+#
+#   pp(obj)             #=> obj
+#   pp obj              #=> obj
+#   pp(obj1, obj2, ...) #=> [obj1, obj2, ...]
+#   pp()                #=> nil
 #
-# = Usage
+# Output <tt>obj(s)</tt> to <tt>$></tt> in pretty printed format.
 #
-#   pp(obj)
+# It returns <tt>obj(s)</tt>.
 #
-# output +obj+ to +$>+ in pretty printed format.
+##
+# == Output Customization
 #
-# It returns +nil+.
+# To define a customized pretty printing function for your classes,
+# redefine method <code>#pretty_print(pp)</code> in the class.
+# Note that <code>require 'pp'</code> is needed before redefining <code>#pretty_print(pp)</code>.
 #
-# = Output Customization
-# To define your customized pretty printing function for your classes,
-# redefine a method #pretty_print(+pp+) in the class.
-# It takes an argument +pp+ which is an instance of the class PP.
-# The method should use PP#text, PP#breakable, PP#nest, PP#group and
-# PP#pp to print the object.
+# <code>#pretty_print</code> takes the +pp+ argument, which is an instance of the PP class.
+# The method uses #text, #breakable, #nest, #group and #pp to print the
+# object.
 #
-# = Author
-# Tanaka Akira <akr@m17n.org>
+##
+# == Pretty-Print JSON
+#
+# To pretty-print JSON refer to JSON#pretty_generate.
+#
+##
+# == Author
+# Tanaka Akira <akr@fsij.org>
 
-require 'prettyprint'
+class PP < PrettyPrint
 
-module Kernel
-  # returns a pretty printed object as a string.
-  def pretty_inspect
-    PP.pp(self, '')
-  end
+  # The version string
+  VERSION = "0.6.3"
 
-  private
-  # prints arguments in pretty form.
+  # Returns the usable width for +out+.
+  # As the width of +out+:
+  # 1. If +out+ is assigned to a tty device, its width is used.
+  # 2. Otherwise, or it could not get the value, the +COLUMN+
+  #    environment variable is assumed to be set to the width.
+  # 3. If +COLUMN+ is not set to a non-zero number, 80 is assumed.
   #
-  # pp returns argument(s).
-  def pp(*objs) # :doc:
-    objs.each {|obj|
-      PP.pp(obj)
-    }
-    objs.size <= 1 ? objs.first : objs
+  # And finally, returns the above width value - 1.
+  # * This -1 is for Windows command prompt, which moves the cursor to
+  #   the next line if it reaches the last column.
+  def PP.width_for(out)
+    begin
+      require 'io/console'
+      _, width = out.winsize
+    rescue LoadError, NoMethodError, SystemCallError
+    end
+    (width || ENV['COLUMNS']&.to_i&.nonzero? || 80) - 1
   end
-  module_function :pp
-end
 
-class PP < PrettyPrint
   # Outputs +obj+ to +out+ in pretty printed format of
   # +width+ columns in width.
   #
-  # If +out+ is omitted, +$>+ is assumed.
-  # If +width+ is omitted, 79 is assumed.
+  # If +out+ is omitted, <code>$></code> is assumed.
+  # If +width+ is omitted, the width of +out+ is assumed (see
+  # width_for).
   #
   # PP.pp returns +out+.
-  def PP.pp(obj, out=$>, width=79)
-    q = PP.new(out, width)
+  def PP.pp(obj, out=$>, width=width_for(out))
+    q = new(out, width)
     q.guard_inspect_key {q.pp obj}
     q.flush
     #$pp = q
@@ -93,67 +114,105 @@ class PP < PrettyPrint
 
   # :stopdoc:
   def PP.mcall(obj, mod, meth, *args, &block)
-    mod.instance_method(meth).bind(obj).call(*args, &block)
+    mod.instance_method(meth).bind_call(obj, *args, &block)
   end
   # :startdoc:
 
-  @sharing_detection = false
-  class << self
-    # Returns the sharing detection flag as a boolean value.
-    # It is false by default.
-    attr_accessor :sharing_detection
-  end
-
-  module PPMethods
-    def guard_inspect_key
-      if Thread.current[:__recursive_key__] == nil
-        Thread.current[:__recursive_key__] = {}.untrust
+  if defined? ::Ractor
+    class << self
+      # Returns the sharing detection flag as a boolean value.
+      # It is false (nil) by default.
+      def sharing_detection
+        Ractor.current[:pp_sharing_detection]
       end
-
-      if Thread.current[:__recursive_key__][:inspect] == nil
-        Thread.current[:__recursive_key__][:inspect] = {}.untrust
+      # Sets the sharing detection flag to b.
+      def sharing_detection=(b)
+        Ractor.current[:pp_sharing_detection] = b
       end
+    end
+  else
+    @sharing_detection = false
+    class << self
+      # Returns the sharing detection flag as a boolean value.
+      # It is false by default.
+      attr_accessor :sharing_detection
+    end
+  end
 
-      save = Thread.current[:__recursive_key__][:inspect]
+  # Module that defines helper methods for pretty_print.
+  module PPMethods
 
+    # Yields to a block
+    # and preserves the previous set of objects being printed.
+    def guard_inspect_key
+      recursive_state = Thread.current[:__recursive_key__] ||= {}.compare_by_identity
+      save = recursive_state[:inspect] ||= {}.compare_by_identity
       begin
-        Thread.current[:__recursive_key__][:inspect] = {}.untrust
+        recursive_state[:inspect] = {}.compare_by_identity
         yield
       ensure
-        Thread.current[:__recursive_key__][:inspect] = save
+        recursive_state[:inspect] = save
       end
     end
 
+    # Check whether the object_id +id+ is in the current buffer of objects
+    # to be pretty printed. Used to break cycles in chains of objects to be
+    # pretty printed.
     def check_inspect_key(id)
-      Thread.current[:__recursive_key__] &&
-      Thread.current[:__recursive_key__][:inspect] &&
-      Thread.current[:__recursive_key__][:inspect].include?(id)
+      recursive_state = Thread.current[:__recursive_key__] or return false
+      recursive_state[:inspect]&.include?(id)
     end
+
+    # Adds the object_id +id+ to the set of objects being pretty printed, so
+    # as to not repeat objects.
     def push_inspect_key(id)
       Thread.current[:__recursive_key__][:inspect][id] = true
     end
+
+    # Removes an object from the set of objects being pretty printed.
     def pop_inspect_key(id)
       Thread.current[:__recursive_key__][:inspect].delete id
     end
 
+    private def guard_inspect(object) # :nodoc:
+      recursive_state = Thread.current[:__recursive_key__]
+
+      if recursive_state&.key?(:inspect)
+        begin
+          push_inspect_key(object)
+          yield
+        ensure
+          pop_inspect_key(object) unless PP.sharing_detection
+        end
+      else
+        guard_inspect_key do
+          push_inspect_key(object)
+          yield
+        end
+      end
+    end
+
     # Adds +obj+ to the pretty printing buffer
     # using Object#pretty_print or Object#pretty_print_cycle.
     #
     # Object#pretty_print_cycle is used when +obj+ is already
     # printed, a.k.a the object reference chain has a cycle.
     def pp(obj)
-      id = obj.object_id
+      # If obj is a Delegator then use the object being delegated to for cycle
+      # detection
+      obj = obj.__getobj__ if defined?(::Delegator) and ::Delegator === obj
 
-      if check_inspect_key(id)
+      if check_inspect_key(obj)
         group {obj.pretty_print_cycle self}
         return
       end
 
-      begin
-        push_inspect_key(id)
-        group {obj.pretty_print self}
-      ensure
-        pop_inspect_key(id) unless PP.sharing_detection
+      guard_inspect(obj) do
+        group do
+          obj.pretty_print self
+        rescue NoMethodError
+          text Kernel.instance_method(:inspect).bind_call(obj)
+        end
       end
     end
 
@@ -164,18 +223,12 @@ class PP < PrettyPrint
       group(1, '#<' + obj.class.name, '>', &block)
     end
 
-    PointerMask = (1 << ([""].pack("p").size * 8)) - 1
-
-    case Object.new.inspect
-    when /\A\#<Object:0x([0-9a-f]+)>\z/
-      PointerFormat = "%0#{$1.length}x"
-    else
-      PointerFormat = "%x"
-    end
-
+    # A convenience method, like object_group, but also reformats the Object's
+    # object_id.
     def object_address_group(obj, &block)
-      id = PointerFormat % (obj.object_id * 2 & PointerMask)
-      group(1, "\#<#{obj.class}:0x#{id}", '>', &block)
+      str = Kernel.instance_method(:to_s).bind_call(obj)
+      str.chomp!('>')
+      group(1, str, '>', &block)
     end
 
     # A convenience method which is same as follows:
@@ -214,16 +267,22 @@ class PP < PrettyPrint
     def seplist(list, sep=nil, iter_method=:each) # :yield: element
       sep ||= lambda { comma_breakable }
       first = true
+      kwsplat = EMPTY_KWHASH
       list.__send__(iter_method) {|*v|
         if first
           first = false
         else
           sep.call
         end
-        yield(*v)
+        kwsplat ? yield(*v, **kwsplat) : yield(*v)
       }
     end
+    EMPTY_KWHASH = if RUBY_VERSION >= "3.0" # :nodoc:
+      {}.freeze
+    end
+    private_constant :EMPTY_KWHASH
 
+    # A present standard failsafe for pretty printing any given Object
     def pp_object(obj)
       object_address_group(obj) {
         seplist(obj.pretty_print_instance_variables, lambda { text ',' }) {|v|
@@ -239,33 +298,57 @@ class PP < PrettyPrint
       }
     end
 
+    # A pretty print for a Hash
     def pp_hash(obj)
       group(1, '{', '}') {
         seplist(obj, nil, :each_pair) {|k, v|
           group {
-            pp k
-            text '=>'
-            group(1) {
-              breakable ''
-              pp v
-            }
+            pp_hash_pair k, v
           }
         }
       }
     end
+
+    if RUBY_VERSION >= '3.4.'
+      # A pretty print for a pair of Hash
+      def pp_hash_pair(k, v)
+        if Symbol === k
+          if k.inspect.match?(%r[\A:["$@!]|[%&*+\-\/<=>@\]^`|~]\z])
+            k = k.to_s.inspect
+          end
+          text "#{k}:"
+        else
+          pp k
+          text ' '
+          text '=>'
+        end
+        group(1) {
+          breakable
+          pp v
+        }
+      end
+    else
+      def pp_hash_pair(k, v)
+        pp k
+        text '=>'
+        group(1) {
+          breakable ''
+          pp v
+        }
+      end
+    end
   end
 
   include PPMethods
 
-  class SingleLine < PrettyPrint::SingleLine
+  class SingleLine < PrettyPrint::SingleLine # :nodoc:
     include PPMethods
   end
 
-  module ObjectMixin
+  module ObjectMixin # :nodoc:
     # 1. specific pretty_print
     # 2. specific inspect
-    # 3. specific to_s
-    # 4. generic pretty_print
+    # 3. generic pretty_print
 
     # A default pretty printing method for general objects.
     # It calls #pretty_print_instance_variables to list instance variables.
@@ -277,23 +360,15 @@ class PP < PrettyPrint
     # This module provides predefined #pretty_print methods for some of
     # the most commonly used built-in classes for convenience.
     def pretty_print(q)
-      method_method = Object.instance_method(:method).bind(self)
-      begin
-        inspect_method = method_method.call(:inspect)
-      rescue NameError
-      end
+      umethod_method = Object.instance_method(:method)
       begin
-        to_s_method = method_method.call(:to_s)
+        inspect_method = umethod_method.bind_call(self, :inspect)
       rescue NameError
       end
-      if inspect_method && /\(Kernel\)#/ !~ inspect_method.inspect
+      if inspect_method && inspect_method.owner != Kernel
         q.text self.inspect
       elsif !inspect_method && self.respond_to?(:inspect)
         q.text self.inspect
-      elsif to_s_method && /\(Kernel\)#/ !~ to_s_method.inspect
-        q.text self.to_s
-      elsif !to_s_method && self.respond_to?(:to_s)
-        q.text self.to_s
       else
         q.pp_object(self)
       end
@@ -313,7 +388,8 @@ class PP < PrettyPrint
     # This method should return an array of names of instance variables as symbols or strings as:
     # +[:@a, :@b]+.
     def pretty_print_instance_variables
-      instance_variables.sort
+      ivars = respond_to?(:instance_variables_to_inspect, true) ? instance_variables_to_inspect || instance_variables : instance_variables
+      ivars.sort
     end
 
     # Is #inspect implementation using #pretty_print.
@@ -324,16 +400,16 @@ class PP < PrettyPrint
     # However, doing this requires that every class that #inspect is called on
     # implement #pretty_print, or a RuntimeError will be raised.
     def pretty_print_inspect
-      if /\(PP::ObjectMixin\)#/ =~ Object.instance_method(:method).bind(self).call(:pretty_print).inspect
+      if Object.instance_method(:method).bind_call(self, :pretty_print).owner == PP::ObjectMixin
         raise "pretty_print is not overridden for #{self.class}"
       end
-      PP.singleline_pp(self, '')
+      PP.singleline_pp(self, ''.dup)
     end
   end
 end
 
-class Array
-  def pretty_print(q)
+class Array # :nodoc:
+  def pretty_print(q) # :nodoc:
     q.group(1, '[', ']') {
       q.seplist(self) {|v|
         q.pp v
@@ -341,23 +417,45 @@ class Array
     }
   end
 
-  def pretty_print_cycle(q)
+  def pretty_print_cycle(q) # :nodoc:
     q.text(empty? ? '[]' : '[...]')
   end
 end
 
-class Hash
-  def pretty_print(q)
+class Hash # :nodoc:
+  def pretty_print(q) # :nodoc:
     q.pp_hash self
   end
 
-  def pretty_print_cycle(q)
+  def pretty_print_cycle(q) # :nodoc:
     q.text(empty? ? '{}' : '{...}')
   end
 end
 
-class << ENV
-  def pretty_print(q)
+if defined?(Set)
+  if set_pp = Set.instance_method(:initialize).source_location
+    set_pp = !set_pp.first.end_with?("/set.rb") # not defined in set.rb
+  else
+    set_pp = true               # defined in C
+  end
+end
+class Set # :nodoc:
+  def pretty_print(pp)  # :nodoc:
+    pp.group(1, "#{self.class.name}[", ']') {
+      pp.seplist(self) { |o|
+        pp.pp o
+      }
+    }
+  end
+
+  def pretty_print_cycle(pp)    # :nodoc:
+    name = self.class.name
+    pp.text(empty? ? "#{name}[]" : "#{name}[...]")
+  end
+end if set_pp
+
+class << ENV # :nodoc:
+  def pretty_print(q) # :nodoc:
     h = {}
     ENV.keys.sort.each {|k|
       h[k] = ENV[k]
@@ -366,8 +464,8 @@ class << ENV
   end
 end
 
-class Struct
-  def pretty_print(q)
+class Struct # :nodoc:
+  def pretty_print(q) # :nodoc:
     q.group(1, sprintf("#<struct %s", PP.mcall(self, Kernel, :class).name), '>') {
       q.seplist(PP.mcall(self, Struct, :members), lambda { q.text "," }) {|member|
         q.breakable
@@ -381,25 +479,83 @@ class Struct
     }
   end
 
-  def pretty_print_cycle(q)
+  def pretty_print_cycle(q) # :nodoc:
     q.text sprintf("#<struct %s:...>", PP.mcall(self, Kernel, :class).name)
   end
 end
 
-class Range
-  def pretty_print(q)
-    q.pp self.begin
+verbose, $VERBOSE = $VERBOSE, nil
+begin
+  has_data_define = defined?(Data.define)
+ensure
+  $VERBOSE = verbose
+end
+
+class Data # :nodoc:
+  def pretty_print(q) # :nodoc:
+    class_name = PP.mcall(self, Kernel, :class).name
+    class_name = " #{class_name}" if class_name
+    q.group(1, "#<data#{class_name}", '>') {
+
+      members = PP.mcall(self, Kernel, :class).members
+      values = []
+      members.select! do |member|
+        begin
+          values << __send__(member)
+          true
+        rescue NoMethodError
+          false
+        end
+      end
+
+      q.seplist(members.zip(values), lambda { q.text "," }) {|(member, value)|
+        q.breakable
+        q.text member.to_s
+        q.text '='
+        q.group(1) {
+          q.breakable ''
+          q.pp value
+        }
+      }
+    }
+  end
+
+  def pretty_print_cycle(q) # :nodoc:
+    q.text sprintf("#<data %s:...>", PP.mcall(self, Kernel, :class).name)
+  end
+end if has_data_define
+
+class Range # :nodoc:
+  def pretty_print(q) # :nodoc:
+    begin_nil = self.begin == nil
+    end_nil = self.end == nil
+    q.pp self.begin if !begin_nil || end_nil
     q.breakable ''
     q.text(self.exclude_end? ? '...' : '..')
     q.breakable ''
-    q.pp self.end
+    q.pp self.end if !end_nil || begin_nil
   end
 end
 
-class File < IO
-  class Stat
-    def pretty_print(q)
-      require 'etc.so'
+class String # :nodoc:
+  def pretty_print(q) # :nodoc:
+    lines = self.lines
+    if lines.size > 1
+      q.group(0, '', '') do
+        q.seplist(lines, lambda { q.text ' +'; q.breakable }) do |v|
+          q.pp v
+        end
+      end
+    else
+      q.text inspect
+    end
+  end
+end
+
+class File < IO # :nodoc:
+  class Stat # :nodoc:
+    def pretty_print(q) # :nodoc:
+      require 'etc'
       q.object_group(self) {
         q.breakable
         q.text sprintf("dev=0x%x", self.dev); q.comma_breakable
@@ -449,8 +605,10 @@ class File < IO
         q.comma_breakable
         q.group {
           q.text sprintf("rdev=0x%x", self.rdev)
-          q.breakable
-          q.text sprintf('(%d, %d)', self.rdev_major, self.rdev_minor)
+          if self.rdev_major && self.rdev_minor
+            q.breakable
+            q.text sprintf('(%d, %d)', self.rdev_major, self.rdev_minor)
+          end
         }
         q.comma_breakable
         q.text "size="; q.pp self.size; q.comma_breakable
@@ -478,8 +636,8 @@ class File < IO
   end
 end
 
-class MatchData
-  def pretty_print(q)
+class MatchData # :nodoc:
+  def pretty_print(q) # :nodoc:
     nc = []
     self.regexp.named_captures.each {|name, indexes|
       indexes.each {|i| nc[i] = name }
@@ -503,7 +661,43 @@ class MatchData
   end
 end
 
-class Object < BasicObject
+if defined?(RubyVM::AbstractSyntaxTree)
+  class RubyVM::AbstractSyntaxTree::Node # :nodoc:
+    def pretty_print_children(q, names = [])
+      children.zip(names) do |c, n|
+        if n
+          q.breakable
+          q.text "#{n}:"
+        end
+        q.group(2) do
+          q.breakable
+          q.pp c
+        end
+      end
+    end
+
+    def pretty_print(q)
+      q.group(1, "(#{type}@#{first_lineno}:#{first_column}-#{last_lineno}:#{last_column}", ")") {
+        case type
+        when :SCOPE
+          pretty_print_children(q, %w"tbl args body")
+        when :ARGS
+          pretty_print_children(q, %w[pre_num pre_init opt first_post post_num post_init rest kw kwrest block])
+        when :DEFN
+          pretty_print_children(q, %w[mid body])
+        when :ARYPTN
+          pretty_print_children(q, %w[const pre rest post])
+        when :HSHPTN
+          pretty_print_children(q, %w[const kw kwrest])
+        else
+          pretty_print_children(q)
+        end
+      }
+    end
+  end
+end
+
+class Object < BasicObject # :nodoc:
   include PP::ObjectMixin
 end
 
@@ -522,3 +716,23 @@ end
     end
   }
 }
+
+module Kernel
+  # Returns a pretty printed object as a string.
+  #
+  # See the PP module for more information.
+  def pretty_inspect
+    PP.pp(self, ''.dup)
+  end
+
+  # prints arguments in pretty form.
+  #
+  # +#pp+ returns argument(s).
+  def pp(*objs)
+    objs.each {|obj|
+      PP.pp(obj)
+    }
+    objs.size <= 1 ? objs.first : objs
+  end
+  module_function :pp
+end
diff --git a/lib/prettyprint.gemspec b/lib/prettyprint.gemspec
new file mode 100644
index 0000000000..a18adb174b
--- /dev/null
+++ b/lib/prettyprint.gemspec
@@ -0,0 +1,29 @@
+name = File.basename(__FILE__, ".gemspec")
+version = ["lib", Array.new(name.count("-")+1).join("/")].find do |dir|
+  break File.foreach(File.join(__dir__, dir, "#{name.tr('-', '/')}.rb")) do |line|
+    /^\s*VERSION\s*=\s*"(.*)"/ =~ line and break $1
+  end rescue nil
+end
+
+Gem::Specification.new do |spec|
+  spec.name          = name
+  spec.version       = version
+  spec.authors       = ["Tanaka Akira"]
+  spec.email         = ["akr@fsij.org"]
+
+  spec.summary       = %q{Implements a pretty printing algorithm for readable structure.}
+  spec.description   = %q{Implements a pretty printing algorithm for readable structure.}
+  spec.homepage      = "https://github.com/ruby/prettyprint"
+  spec.required_ruby_version = Gem::Requirement.new(">= 2.3.0")
+  spec.licenses      = ["Ruby", "BSD-2-Clause"]
+
+  spec.metadata["homepage_uri"] = spec.homepage
+  spec.metadata["source_code_uri"] = spec.homepage
+
+  spec.files         = Dir.chdir(File.expand_path('..', __FILE__)) do
+    `git ls-files -z`.split("\x0").reject { |f| f.match(%r{^(test|spec|features)/}) }
+  end
+  spec.bindir        = "exe"
+  spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
+  spec.require_paths = ["lib"]
+end
diff --git a/lib/prettyprint.rb b/lib/prettyprint.rb
index 9a90713a4d..44ca5e816f 100644
--- a/lib/prettyprint.rb
+++ b/lib/prettyprint.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+#
 # This class implements a pretty printing algorithm. It finds line breaks and
 # nice indentations for grouped structure.
 #
@@ -17,18 +19,23 @@
 # * Box based formatting?
 # * Other (better) model/algorithm?
 #
+# Report any bugs at http://bugs.ruby-lang.org
+#
 # == References
 # Christian Lindig, Strictly Pretty, March 2000,
-# http://www.st.cs.uni-sb.de/~lindig/papers/#pretty
+# https://lindig.github.io/papers/strictly-pretty-2000.pdf
 #
 # Philip Wadler, A prettier printer, March 1998,
-# http://homepages.inf.ed.ac.uk/wadler/topics/language-design.html#prettier
+# https://homepages.inf.ed.ac.uk/wadler/topics/language-design.html#prettier
 #
 # == Author
-# Tanaka Akira <akr@m17n.org>
+# Tanaka Akira <akr@fsij.org>
 #
 class PrettyPrint
 
+  # The version string
+  VERSION = "0.2.0"
+
   # This is a convenience method which is same as follows:
   #
   #   begin
@@ -38,7 +45,7 @@ class PrettyPrint
   #     output
   #   end
   #
-  def PrettyPrint.format(output='', maxwidth=79, newline="\n", genspace=lambda {|n| ' ' * n})
+  def PrettyPrint.format(output=''.dup, maxwidth=79, newline="\n", genspace=lambda {|n| ' ' * n})
     q = PrettyPrint.new(output, maxwidth, newline, &genspace)
     yield q
     q.flush
@@ -52,7 +59,7 @@ class PrettyPrint
   # The invocation of +breakable+ in the block doesn't break a line and is
   # treated as just an invocation of +text+.
   #
-  def PrettyPrint.singleline_format(output='', maxwidth=nil, newline=nil, genspace=nil)
+  def PrettyPrint.singleline_format(output=''.dup, maxwidth=nil, newline=nil, genspace=nil)
     q = SingleLine.new(output)
     yield q
     output
@@ -75,7 +82,7 @@ class PrettyPrint
   # The block is used to generate spaces. {|width| ' ' * width} is used if it
   # is not given.
   #
-  def initialize(output='', maxwidth=79, newline="\n", &genspace)
+  def initialize(output=''.dup, maxwidth=79, newline="\n", &genspace)
     @output = output
     @maxwidth = maxwidth
     @newline = newline
@@ -90,34 +97,66 @@ class PrettyPrint
     @group_queue = GroupQueue.new(root_group)
     @indent = 0
   end
-  attr_reader :output, :maxwidth, :newline, :genspace
-  attr_reader :indent, :group_queue
 
-  # Returns the group most recently added to the stack.
-  def current_group
-    @group_stack.last
-  end
+  # The output object.
+  #
+  # This defaults to '', and should accept the << method
+  attr_reader :output
 
-  # first? is a predicate to test the call is a first call to first? with
-  # current group.
+  # The maximum width of a line, before it is separated in to a newline
   #
-  # It is useful to format comma separated values as:
+  # This defaults to 79, and should be an Integer
+  attr_reader :maxwidth
+
+  # The value that is appended to +output+ to add a new line.
   #
-  #   q.group(1, '[', ']') {
-  #     xxx.each {|yyy|
-  #       unless q.first?
-  #         q.text ','
-  #         q.breakable
-  #       end
-  #       ... pretty printing yyy ...
-  #     }
-  #   }
+  # This defaults to "\n", and should be String
+  attr_reader :newline
+
+  # A lambda or Proc, that takes one argument, of an Integer, and returns
+  # the corresponding number of spaces.
   #
-  # first? is obsoleted in 1.8.2.
+  # By default this is:
+  #   lambda {|n| ' ' * n}
+  attr_reader :genspace
+
+  # The number of spaces to be indented
+  attr_reader :indent
+
+  # The PrettyPrint::GroupQueue of groups in stack to be pretty printed
+  attr_reader :group_queue
+
+  # Returns the group most recently added to the stack.
   #
-  def first?
-    warn "PrettyPrint#first? is obsoleted at 1.8.2."
-    current_group.first?
+  # Contrived example:
+  #   out = ""
+  #   => ""
+  #   q = PrettyPrint.new(out)
+  #   => #<PrettyPrint:0x82f85c0 @output="", @maxwidth=79, @newline="\n", @genspace=#<Proc:0x82f8368@/home/vbatts/.rvm/rubies/ruby-head/lib/ruby/2.0.0/prettyprint.rb:82 (lambda)>, @output_width=0, @buffer_width=0, @buffer=[], @group_stack=[#<PrettyPrint::Group:0x82f8138 @depth=0, @breakables=[], @break=false>], @group_queue=#<PrettyPrint::GroupQueue:0x82fb7c0 @queue=[[#<PrettyPrint::Group:0x82f8138 @depth=0, @breakables=[], @break=false>]]>, @indent=0>
+  #   q.group {
+  #     q.text q.current_group.inspect
+  #     q.text q.newline
+  #     q.group(q.current_group.depth + 1) {
+  #       q.text q.current_group.inspect
+  #       q.text q.newline
+  #       q.group(q.current_group.depth + 1) {
+  #         q.text q.current_group.inspect
+  #         q.text q.newline
+  #         q.group(q.current_group.depth + 1) {
+  #           q.text q.current_group.inspect
+  #           q.text q.newline
+  #         }
+  #       }
+  #     }
+  #   }
+  #   => 284
+  #    puts out
+  #   #<PrettyPrint::Group:0x8354758 @depth=1, @breakables=[], @break=false>
+  #   #<PrettyPrint::Group:0x8354550 @depth=2, @breakables=[], @break=false>
+  #   #<PrettyPrint::Group:0x83541cc @depth=3, @breakables=[], @break=false>
+  #   #<PrettyPrint::Group:0x8347e54 @depth=4, @breakables=[], @break=false>
+  def current_group
+    @group_stack.last
   end
 
   # Breaks the buffer into lines that are shorter than #maxwidth
@@ -166,7 +205,7 @@ class PrettyPrint
   # may cause 2 results:
   # (break,break), (non-break,non-break).
   #
-  # The text sep+ is inserted if a line is not broken at this point.
+  # The text +sep+ is inserted if a line is not broken at this point.
   #
   # If +sep+ is not specified, " " is used.
   #
@@ -220,6 +259,7 @@ class PrettyPrint
     text close_obj, close_width
   end
 
+  # Takes a block and queues a new group that is indented 1 level further.
   def group_sub
     group = Group.new(@group_stack.last.depth + 1)
     @group_stack.push group
@@ -256,25 +296,55 @@ class PrettyPrint
     @buffer_width = 0
   end
 
-  class Text
+  # The Text class is the means by which to collect strings from objects.
+  #
+  # This class is intended for internal use of the PrettyPrint buffers.
+  class Text # :nodoc:
+
+    # Creates a new text object.
+    #
+    # This constructor takes no arguments.
+    #
+    # The workflow is to append a PrettyPrint::Text object to the buffer, and
+    # being able to call the buffer.last() to reference it.
+    #
+    # As there are objects, use PrettyPrint::Text#add to include the objects
+    # and the width to utilized by the String version of this object.
     def initialize
       @objs = []
       @width = 0
     end
+
+    # The total width of the objects included in this Text object.
     attr_reader :width
 
+    # Render the String text of the objects that have been added to this Text object.
+    #
+    # Output the text to +out+, and increment the width to +output_width+
     def output(out, output_width)
       @objs.each {|obj| out << obj}
       output_width + @width
     end
 
+    # Include +obj+ in the objects to be pretty printed, and increment
+    # this Text object's total width by +width+
     def add(obj, width)
       @objs << obj
       @width += width
     end
   end
 
-  class Breakable
+  # The Breakable class is used for breaking up object information
+  #
+  # This class is intended for internal use of the PrettyPrint buffers.
+  class Breakable # :nodoc:
+
+    # Create a new Breakable object.
+    #
+    # Arguments:
+    # * +sep+ String of the separator
+    # * +width+ Integer width of the +sep+
+    # * +q+ parent PrettyPrint object, to base from
     def initialize(sep, width, q)
       @obj = sep
       @width = width
@@ -283,8 +353,24 @@ class PrettyPrint
       @group = q.current_group
       @group.breakables.push self
     end
-    attr_reader :obj, :width, :indent
 
+    # Holds the separator String
+    #
+    # The +sep+ argument from ::new
+    attr_reader :obj
+
+    # The width of +obj+ / +sep+
+    attr_reader :width
+
+    # The number of spaces to indent.
+    #
+    # This is inferred from +q+ within PrettyPrint, passed in ::new
+    attr_reader :indent
+
+    # Render the String text of the objects that have been added to this
+    # Breakable object.
+    #
+    # Output the text to +out+, and increment the width to +output_width+
     def output(out, output_width)
       @group.breakables.shift
       if @group.break?
@@ -299,22 +385,45 @@ class PrettyPrint
     end
   end
 
-  class Group
+  # The Group class is used for making indentation easier.
+  #
+  # While this class does neither the breaking into newlines nor indentation,
+  # it is used in a stack (as well as a queue) within PrettyPrint, to group
+  # objects.
+  #
+  # For information on using groups, see PrettyPrint#group
+  #
+  # This class is intended for internal use of the PrettyPrint buffers.
+  class Group # :nodoc:
+    # Create a Group object
+    #
+    # Arguments:
+    # * +depth+ - this group's relation to previous groups
     def initialize(depth)
       @depth = depth
       @breakables = []
       @break = false
     end
-    attr_reader :depth, :breakables
 
+    # This group's relation to previous groups
+    attr_reader :depth
+
+    # Array to hold the Breakable objects for this Group
+    attr_reader :breakables
+
+    # Makes a break for this Group, and returns true
     def break
       @break = true
     end
 
+    # Boolean of whether this Group has made a break
     def break?
       @break
     end
 
+    # Boolean of whether this Group has been queried for being first
+    #
+    # This is used as a predicate, and ought to be called first.
     def first?
       if defined? @first
         false
@@ -325,18 +434,33 @@ class PrettyPrint
     end
   end
 
-  class GroupQueue
+  # The GroupQueue class is used for managing the queue of Group to be pretty
+  # printed.
+  #
+  # This queue groups the Group objects, based on their depth.
+  #
+  # This class is intended for internal use of the PrettyPrint buffers.
+  class GroupQueue # :nodoc:
+    # Create a GroupQueue object
+    #
+    # Arguments:
+    # * +groups+ - one or more PrettyPrint::Group objects
     def initialize(*groups)
       @queue = []
       groups.each {|g| enq g}
     end
 
+    # Enqueue +group+
+    #
+    # This does not strictly append the group to the end of the queue,
+    # but instead adds it in line, base on the +group.depth+
     def enq(group)
       depth = group.depth
       @queue << [] until depth < @queue.length
       @queue[depth] << group
     end
 
+    # Returns the outer group of the queue
     def deq
       @queue.each {|gs|
         (gs.length-1).downto(0) {|i|
@@ -352,29 +476,76 @@ class PrettyPrint
       return nil
     end
 
+    # Remote +group+ from this queue
     def delete(group)
       @queue[group.depth].delete(group)
     end
   end
 
+  # PrettyPrint::SingleLine is used by PrettyPrint.singleline_format
+  #
+  # It is passed to be similar to a PrettyPrint object itself, by responding to:
+  # * #text
+  # * #breakable
+  # * #fill_breakable
+  # * #nest
+  # * #group
+  # * #group_sub
+  # * #flush
+  # * #first?
+  #
+  # but instead, the output has no line breaks
+  #
   class SingleLine
+    # Create a PrettyPrint::SingleLine object
+    #
+    # Arguments:
+    # * +output+ - String (or similar) to store rendered text. Needs to respond to '<<'
+    # * +maxwidth+ - Argument position expected to be here for compatibility.
+    #                This argument is a noop.
+    # * +newline+ - Argument position expected to be here for compatibility.
+    #               This argument is a noop.
     def initialize(output, maxwidth=nil, newline=nil)
       @output = output
       @first = [true]
     end
 
+    # Add +obj+ to the text to be output.
+    #
+    # +width+ argument is here for compatibility. It is a noop argument.
     def text(obj, width=nil)
       @output << obj
     end
 
+    # Appends +sep+ to the text to be output. By default +sep+ is ' '
+    #
+    # +width+ argument is here for compatibility. It is a noop argument.
     def breakable(sep=' ', width=nil)
       @output << sep
     end
 
-    def nest(indent)
+    # Appends +sep+ to the text to be output. By default +sep+ is ' '
+    #
+    # +width+ argument is here for compatibility. It is a noop argument.
+    def fill_breakable(sep=' ', width=nil)
+      @output << sep
+    end
+
+    # Takes +indent+ arg, but does nothing with it.
+    #
+    # Yields to a block.
+    def nest(indent) # :nodoc:
       yield
     end
 
+    # Opens a block for grouping objects to be pretty printed.
+    #
+    # Arguments:
+    # * +indent+ - noop argument. Present for compatibility.
+    # * +open_obj+ - text appended before the &blok. Default is ''
+    # * +close_obj+ - text appended after the &blok. Default is ''
+    # * +open_width+ - noop argument. Present for compatibility.
+    # * +close_width+ - noop argument. Present for compatibility.
     def group(indent=nil, open_obj='', close_obj='', open_width=nil, close_width=nil)
       @first.push true
       @output << open_obj
@@ -383,9 +554,20 @@ class PrettyPrint
       @first.pop
     end
 
-    def flush
+    # Yields to a block for compatibility.
+    def group_sub # :nodoc:
+      yield
+    end
+
+    # Method present for compatibility, but is a noop
+    def break_outmost_groups # :nodoc:
+    end
+
+    # Method present for compatibility, but is a noop
+    def flush # :nodoc:
     end
 
+    # This is used as a predicate, and ought to be called first.
     def first?
       result = @first[-1]
       @first[-1] = false
diff --git a/lib/prime.rb b/lib/prime.rb
deleted file mode 100644
index 4a20d93fb7..0000000000
--- a/lib/prime.rb
+++ /dev/null
@@ -1,509 +0,0 @@
-#
-# = prime.rb
-#
-# Prime numbers and factorization library.
-#
-# Copyright::
-#   Copyright (c) 1998-2008 Keiju ISHITSUKA(SHL Japan Inc.)
-#   Copyright (c) 2008 Yuki Sonoda (Yugui) <yugui@yugui.jp>
-#
-# Documentation::
-#   Yuki Sonoda
-#
-
-require "singleton"
-require "forwardable"
-
-class Integer
-  # Re-composes a prime factorization and returns the product.
-  #
-  # See Prime#int_from_prime_division for more details.
-  def Integer.from_prime_division(pd)
-    Prime.int_from_prime_division(pd)
-  end
-
-  # Returns the factorization of +self+.
-  #
-  # See Prime#prime_division for more details.
-  def prime_division(generator = Prime::Generator23.new)
-    Prime.prime_division(self, generator)
-  end
-
-  # Returns true if +self+ is a prime number, false for a composite.
-  def prime?
-    Prime.prime?(self)
-  end
-
-  # Iterates the given block over all prime numbers.
-  #
-  # See +Prime+#each for more details.
-  def Integer.each_prime(ubound, &block) # :yields: prime
-    Prime.each(ubound, &block)
-  end
-end
-
-#
-# The set of all prime numbers.
-#
-# == Example
-#
-#   Prime.each(100) do |prime|
-#     p prime  #=> 2, 3, 5, 7, 11, ...., 97
-#   end
-#
-# Prime is Enumerable:
-#
-#   Prime.first 5 # => [2, 3, 5, 7, 11]
-#
-# == Retrieving the instance
-#
-# +Prime+.new is obsolete. Now +Prime+ has the default instance and you can
-# access it as +Prime+.instance.
-#
-# For convenience, each instance method of +Prime+.instance can be accessed
-# as a class method of +Prime+.
-#
-# e.g.
-#   Prime.instance.prime?(2)  #=> true
-#   Prime.prime?(2)           #=> true
-#
-# == Generators
-#
-# A "generator" provides an implementation of enumerating pseudo-prime
-# numbers and it remembers the position of enumeration and upper bound.
-# Futhermore, it is a external iterator of prime enumeration which is
-# compatible to an Enumerator.
-#
-# +Prime+::+PseudoPrimeGenerator+ is the base class for generators.
-# There are few implementations of generator.
-#
-# [+Prime+::+EratosthenesGenerator+]
-#   Uses eratosthenes's sieve.
-# [+Prime+::+TrialDivisionGenerator+]
-#   Uses the trial division method.
-# [+Prime+::+Generator23+]
-#   Generates all positive integers which is not divided by 2 nor 3.
-#   This sequence is very bad as a pseudo-prime sequence. But this
-#   is faster and uses much less memory than other generators. So,
-#   it is suitable for factorizing an integer which is not large but
-#   has many prime factors. e.g. for Prime#prime? .
-
-class Prime
-  include Enumerable
-  @the_instance = Prime.new
-
-  # obsolete. Use +Prime+::+instance+ or class methods of +Prime+.
-  def initialize
-    @generator = EratosthenesGenerator.new
-    extend OldCompatibility
-    warn "Prime::new is obsolete. use Prime::instance or class methods of Prime."
-  end
-
-  class << self
-    extend Forwardable
-    include Enumerable
-    # Returns the default instance of Prime.
-    def instance; @the_instance end
-
-    def method_added(method) # :nodoc:
-      (class<< self;self;end).def_delegator :instance, method
-    end
-  end
-
-  # Iterates the given block over all prime numbers.
-  #
-  # == Parameters
-  #
-  # +ubound+::
-  #   Optional. An arbitrary positive number.
-  #   The upper bound of enumeration. The method enumerates
-  #   prime numbers infinitely if +ubound+ is nil.
-  # +generator+::
-  #   Optional. An implementation of pseudo-prime generator.
-  #
-  # == Return value
-  #
-  # An evaluated value of the given block at the last time.
-  # Or an enumerator which is compatible to an +Enumerator+
-  # if no block given.
-  #
-  # == Description
-  #
-  # Calls +block+ once for each prime number, passing the prime as
-  # a parameter.
-  #
-  # +ubound+::
-  #   Upper bound of prime numbers. The iterator stops after
-  #   yields all prime numbers p <= +ubound+.
-  #
-  # == Note
-  #
-  # +Prime+.+new+ returns a object extended by +Prime+::+OldCompatibility+
-  # in order to compatibility to Ruby 1.8, and +Prime+#each is overwritten
-  # by +Prime+::+OldCompatibility+#+each+.
-  #
-  # +Prime+.+new+ is now obsolete. Use +Prime+.+instance+.+each+ or simply
-  # +Prime+.+each+.
-  def each(ubound = nil, generator = EratosthenesGenerator.new, &block)
-    generator.upper_bound = ubound
-    generator.each(&block)
-  end
-
-
-  # Returns true if +value+ is prime, false for a composite.
-  #
-  # == Parameters
-  #
-  # +value+:: an arbitrary integer to be checked.
-  # +generator+:: optional. A pseudo-prime generator.
-  def prime?(value, generator = Prime::Generator23.new)
-    value = -value if value < 0
-    return false if value < 2
-    for num in generator
-      q,r = value.divmod num
-      return true if q < num
-      return false if r == 0
-    end
-  end
-
-  # Re-composes a prime factorization and returns the product.
-  #
-  # == Parameters
-  # +pd+:: Array of pairs of integers. The each internal
-  #        pair consists of a prime number -- a prime factor --
-  #        and a natural number -- an exponent.
-  #
-  # == Example
-  # For <tt>[[p_1, e_1], [p_2, e_2], ...., [p_n, e_n]]</tt>, it returns:
-  #
-  #   p_1**e_1 * p_2**e_2 * .... * p_n**e_n.
-  #
-  #   Prime.int_from_prime_division([[2,2], [3,1]])  #=> 12
-  def int_from_prime_division(pd)
-    pd.inject(1){|value, (prime, index)|
-      value *= prime**index
-    }
-  end
-
-  # Returns the factorization of +value+.
-  #
-  # == Parameters
-  # +value+:: An arbitrary integer.
-  # +generator+:: Optional. A pseudo-prime generator.
-  #               +generator+.succ must return the next
-  #               pseudo-prime number in the ascendent
-  #               order. It must generate all prime numbers,
-  #               but may generate non prime numbers.
-  #
-  # === Exceptions
-  # +ZeroDivisionError+:: when +value+ is zero.
-  #
-  # == Example
-  # For an arbitrary integer:
-  #
-  #   n = p_1**e_1 * p_2**e_2 * .... * p_n**e_n,
-  #
-  # prime_division(n) returns:
-  #
-  #   [[p_1, e_1], [p_2, e_2], ...., [p_n, e_n]].
-  #
-  #   Prime.prime_division(12) #=> [[2,2], [3,1]]
-  #
-  def prime_division(value, generator= Prime::Generator23.new)
-    raise ZeroDivisionError if value == 0
-    if value < 0
-      value = -value
-      pv = [[-1, 1]]
-    else
-      pv = []
-    end
-    for prime in generator
-      count = 0
-      while (value1, mod = value.divmod(prime)
-             mod) == 0
-        value = value1
-        count += 1
-      end
-      if count != 0
-        pv.push [prime, count]
-      end
-      break if value1 <= prime
-    end
-    if value > 1
-      pv.push [value, 1]
-    end
-    return pv
-  end
-
-  # An abstract class for enumerating pseudo-prime numbers.
-  #
-  # Concrete subclasses should override succ, next, rewind.
-  class PseudoPrimeGenerator
-    include Enumerable
-
-    def initialize(ubound = nil)
-      @ubound = ubound
-    end
-
-    def upper_bound=(ubound)
-      @ubound = ubound
-    end
-    def upper_bound
-      @ubound
-    end
-
-    # returns the next pseudo-prime number, and move the internal
-    # position forward.
-    #
-    # +PseudoPrimeGenerator+#succ raises +NotImplementedError+.
-    def succ
-      raise NotImplementedError, "need to define `succ'"
-    end
-
-    # alias of +succ+.
-    def next
-      raise NotImplementedError, "need to define `next'"
-    end
-
-    # Rewinds the internal position for enumeration.
-    #
-    # See +Enumerator+#rewind.
-    def rewind
-      raise NotImplementedError, "need to define `rewind'"
-    end
-
-    # Iterates the given block for each prime numbers.
-    def each(&block)
-      return self.dup unless block
-      if @ubound
-        last_value = nil
-        loop do
-          prime = succ
-          break last_value if prime > @ubound
-          last_value = block.call(prime)
-        end
-      else
-        loop do
-          block.call(succ)
-        end
-      end
-    end
-
-    # see +Enumerator+#with_index.
-    alias with_index each_with_index
-
-    # see +Enumerator+#with_object.
-    def with_object(obj)
-      return enum_for(:with_object) unless block_given?
-      each do |prime|
-        yield prime, obj
-      end
-    end
-  end
-
-  # An implementation of +PseudoPrimeGenerator+.
-  #
-  # Uses +EratosthenesSieve+.
-  class EratosthenesGenerator < PseudoPrimeGenerator
-    def initialize
-      @last_prime = nil
-      super
-    end
-
-    def succ
-      @last_prime = @last_prime ? EratosthenesSieve.instance.next_to(@last_prime) : 2
-    end
-    def rewind
-      initialize
-    end
-    alias next succ
-  end
-
-  # An implementation of +PseudoPrimeGenerator+ which uses
-  # a prime table generated by trial division.
-  class TrialDivisionGenerator<PseudoPrimeGenerator
-    def initialize
-      @index = -1
-      super
-    end
-
-    def succ
-      TrialDivision.instance[@index += 1]
-    end
-    def rewind
-      initialize
-    end
-    alias next succ
-  end
-
-  # Generates all integer which are greater than 2 and
-  # are not divided by 2 nor 3.
-  #
-  # This is a pseudo-prime generator, suitable on
-  # checking primality of a integer by brute force
-  # method.
-  class Generator23<PseudoPrimeGenerator
-    def initialize
-      @prime = 1
-      @step = nil
-      super
-    end
-
-    def succ
-      loop do
-        if (@step)
-          @prime += @step
-          @step = 6 - @step
-        else
-          case @prime
-          when 1; @prime = 2
-          when 2; @prime = 3
-          when 3; @prime = 5; @step = 2
-          end
-        end
-        return @prime
-      end
-    end
-    alias next succ
-    def rewind
-      initialize
-    end
-  end
-
-  # Internal use. An implementation of prime table by trial division method.
-  class TrialDivision
-    include Singleton
-
-    def initialize # :nodoc:
-      # These are included as class variables to cache them for later uses.  If memory
-      #   usage is a problem, they can be put in Prime#initialize as instance variables.
-
-      # There must be no primes between @primes[-1] and @next_to_check.
-      @primes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101]
-      # @next_to_check % 6 must be 1.
-      @next_to_check = 103            # @primes[-1] - @primes[-1] % 6 + 7
-      @ulticheck_index = 3            # @primes.index(@primes.reverse.find {|n|
-      #   n < Math.sqrt(@@next_to_check) })
-      @ulticheck_next_squared = 121   # @primes[@ulticheck_index + 1] ** 2
-    end
-
-    # Returns the cached prime numbers.
-    def cache
-      return @primes
-    end
-    alias primes cache
-    alias primes_so_far cache
-
-    # Returns the +index+th prime number.
-    #
-    # +index+ is a 0-based index.
-    def [](index)
-      while index >= @primes.length
-        # Only check for prime factors up to the square root of the potential primes,
-        #   but without the performance hit of an actual square root calculation.
-        if @next_to_check + 4 > @ulticheck_next_squared
-          @ulticheck_index += 1
-          @ulticheck_next_squared = @primes.at(@ulticheck_index + 1) ** 2
-        end
-        # Only check numbers congruent to one and five, modulo six. All others
-
-        #   are divisible by two or three.  This also allows us to skip checking against
-        #   two and three.
-        @primes.push @next_to_check if @primes[2..@ulticheck_index].find {|prime| @next_to_check % prime == 0 }.nil?
-        @next_to_check += 4
-        @primes.push @next_to_check if @primes[2..@ulticheck_index].find {|prime| @next_to_check % prime == 0 }.nil?
-        @next_to_check += 2
-      end
-      return @primes[index]
-    end
-  end
-
-  # Internal use. An implementation of eratosthenes's sieve
-  class EratosthenesSieve
-    include Singleton
-
-    BITS_PER_ENTRY = 16  # each entry is a set of 16-bits in a Fixnum
-    NUMS_PER_ENTRY = BITS_PER_ENTRY * 2 # twiced because even numbers are omitted
-    ENTRIES_PER_TABLE = 8
-    NUMS_PER_TABLE = NUMS_PER_ENTRY * ENTRIES_PER_TABLE
-    FILLED_ENTRY = (1 << NUMS_PER_ENTRY) - 1
-
-    def initialize # :nodoc:
-      # bitmap for odd prime numbers less than 256.
-      # For an arbitrary odd number n, @tables[i][j][k] is
-      # * 1 if n is prime,
-      # * 0 if n is composite,
-      # where i,j,k = indices(n)
-      @tables = [[0xcb6e, 0x64b4, 0x129a, 0x816d, 0x4c32, 0x864a, 0x820d, 0x2196].freeze]
-    end
-
-    # returns the least odd prime number which is greater than +n+.
-    def next_to(n)
-      n = (n-1).div(2)*2+3 # the next odd number to given n
-      table_index, integer_index, bit_index = indices(n)
-      loop do
-        extend_table until @tables.length > table_index
-        for j in integer_index...ENTRIES_PER_TABLE
-          if !@tables[table_index][j].zero?
-            for k in bit_index...BITS_PER_ENTRY
-              return NUMS_PER_TABLE*table_index + NUMS_PER_ENTRY*j + 2*k+1 if !@tables[table_index][j][k].zero?
-            end
-          end
-          bit_index = 0
-        end
-        table_index += 1; integer_index = 0
-      end
-    end
-
-    private
-    # for an odd number +n+, returns (i, j, k) such that @tables[i][j][k] represents primarity of the number
-    def indices(n)
-      #   binary digits of n: |0|1|2|3|4|5|6|7|8|9|10|11|....
-      #   indices:            |-|    k  |  j  |     i
-      # because of NUMS_PER_ENTRY, NUMS_PER_TABLE
-
-      k = (n & 0b00011111) >> 1
-      j = (n & 0b11100000) >> 5
-      i = n >> 8
-      return i, j, k
-    end
-
-    def extend_table
-      lbound = NUMS_PER_TABLE * @tables.length
-      ubound = lbound + NUMS_PER_TABLE
-      new_table = [FILLED_ENTRY] * ENTRIES_PER_TABLE # which represents primarity in lbound...ubound
-      (3..Integer(Math.sqrt(ubound))).step(2) do |p|
-        i, j, k = indices(p)
-        next if @tables[i][j][k].zero?
-
-        start = (lbound.div(p)+1)*p  # least multiple of p which is >= lbound
-        start += p if start.even?
-        (start...ubound).step(2*p) do |n|
-          _, j, k = indices(n)
-          new_table[j] &= FILLED_ENTRY^(1<<k)
-        end
-      end
-      @tables << new_table.freeze
-    end
-  end
-
-  # Provides a +Prime+ object with compatibility to Ruby 1.8 when instantiated via +Prime+.+new+.
-  module OldCompatibility
-    # Returns the next prime number and forwards internal pointer.
-    def succ
-      @generator.succ
-    end
-    alias next succ
-
-    # Overwrites Prime#each.
-    #
-    # Iterates the given block over all prime numbers. Note that enumeration
-    # starts from the current position of internal pointer, not rewound.
-    def each(&block)
-      return @generator.dup unless block_given?
-      loop do
-        yield succ
-      end
-    end
-  end
-end
diff --git a/lib/prism.rb b/lib/prism.rb
new file mode 100644
index 0000000000..8f0342724a
--- /dev/null
+++ b/lib/prism.rb
@@ -0,0 +1,145 @@
+# frozen_string_literal: true
+# :markup: markdown
+#--
+# rbs_inline: enabled
+
+# The Prism Ruby parser.
+#
+# "Parsing Ruby is suddenly manageable!"
+#   - You, hopefully
+#
+module Prism
+  # There are many files in prism that are templated to handle every node type,
+  # which means the files can end up being quite large. We autoload them to make
+  # our require speed faster since consuming libraries are unlikely to use all
+  # of these features.
+
+  autoload :BasicVisitor, "prism/visitor"
+  autoload :Compiler, "prism/compiler"
+  autoload :DesugarCompiler, "prism/desugar_compiler"
+  autoload :Dispatcher, "prism/dispatcher"
+  autoload :DotVisitor, "prism/dot_visitor"
+  autoload :DSL, "prism/dsl"
+  autoload :InspectVisitor, "prism/inspect_visitor"
+  autoload :LexCompat, "prism/lex_compat"
+  autoload :MutationCompiler, "prism/mutation_compiler"
+  autoload :NodeFind, "prism/node_find"
+  autoload :Pattern, "prism/pattern"
+  autoload :Reflection, "prism/reflection"
+  autoload :Relocation, "prism/relocation"
+  autoload :Serialize, "prism/serialize"
+  autoload :StringQuery, "prism/string_query"
+  autoload :Translation, "prism/translation"
+  autoload :Visitor, "prism/visitor"
+
+  # Some of these constants are not meant to be exposed, so marking them as
+  # private here.
+
+  if RUBY_ENGINE != "jruby"
+    private_constant :LexCompat
+    private_constant :NodeFind
+  end
+
+  # Raised when requested to parse as the currently running Ruby version but Prism has no support for it.
+  class CurrentVersionError < ArgumentError
+    # Initialize a new exception for the given ruby version string.
+    #--
+    #: (String version) -> void
+    def initialize(version)
+      message = +"invalid version: Requested to parse as `version: 'current'`; "
+      major, minor, =
+        if version.match?(/\A\d+\.\d+.\d+\z/)
+          version.split(".").map(&:to_i)
+        end
+
+      if major && minor && ((major < 3) || (major == 3 && minor < 3))
+        message << " #{version} is below the minimum supported syntax."
+      else
+        message << " #{version} is unknown. Please update the `prism` gem."
+      end
+
+      super(message)
+    end
+  end
+
+  # :call-seq:
+  #   lex_compat(source, **options) -> LexCompat::Result
+  #
+  # Returns a parse result whose value is an array of tokens that closely
+  # resembles the return value of Ripper.lex.
+  #
+  # For supported options, see Prism.parse.
+  #--
+  #: (String source, **untyped options) -> LexCompat::Result
+  def self.lex_compat(source, **options)
+    LexCompat.new(source, **options).result # steep:ignore
+  end
+
+  # :call-seq:
+  #   load(source, serialized, freeze) -> ParseResult
+  #
+  # Load the serialized AST using the source as a reference into a tree.
+  #--
+  #: (String source, String serialized, ?bool freeze) -> ParseResult
+  def self.load(source, serialized, freeze = false)
+    Serialize.load_parse(source, serialized, freeze)
+  end
+
+  # Given a Method, UnboundMethod, Proc, or Thread::Backtrace::Location,
+  # returns the Prism node representing it. On CRuby, this uses node_id for
+  # an exact match. On other implementations, it falls back to best-effort
+  # matching by source location line number.
+  #--
+  #: (Method | UnboundMethod | Proc | Thread::Backtrace::Location callable, ?rubyvm: bool) -> Node?
+  def self.find(callable, rubyvm: !!defined?(RubyVM))
+    NodeFind.find(callable, rubyvm)
+  end
+
+  # @rbs!
+  #    VERSION: String
+  #    BACKEND: :CEXT | :FFI
+  #
+  #    interface _Stream
+  #      def gets: (?Integer integer) -> (String | nil)
+  #    end
+  #
+  #    def self.parse:               (String source,  ?filepath: String, ?command_line: String, ?encoding: Encoding | false, ?freeze: bool, ?frozen_string_literal: bool, ?line: Integer, ?main_script: bool, ?partial_script: bool, ?scopes: Array[Array[Symbol]], ?version: String) -> ParseResult
+  #    def self.profile:             (String source,  ?filepath: String, ?command_line: String, ?encoding: Encoding | false, ?freeze: bool, ?frozen_string_literal: bool, ?line: Integer, ?main_script: bool, ?partial_script: bool, ?scopes: Array[Array[Symbol]], ?version: String) -> void
+  #    def self.lex:                 (String source,  ?filepath: String, ?command_line: String, ?encoding: Encoding | false, ?freeze: bool, ?frozen_string_literal: bool, ?line: Integer, ?main_script: bool, ?partial_script: bool, ?scopes: Array[Array[Symbol]], ?version: String) -> LexResult
+  #    def self.parse_lex:           (String source,  ?filepath: String, ?command_line: String, ?encoding: Encoding | false, ?freeze: bool, ?frozen_string_literal: bool, ?line: Integer, ?main_script: bool, ?partial_script: bool, ?scopes: Array[Array[Symbol]], ?version: String) -> ParseLexResult
+  #    def self.dump:                (String source,  ?filepath: String, ?command_line: String, ?encoding: Encoding | false, ?freeze: bool, ?frozen_string_literal: bool, ?line: Integer, ?main_script: bool, ?partial_script: bool, ?scopes: Array[Array[Symbol]], ?version: String) -> String
+  #    def self.parse_comments:      (String source,  ?filepath: String, ?command_line: String, ?encoding: Encoding | false, ?freeze: bool, ?frozen_string_literal: bool, ?line: Integer, ?main_script: bool, ?partial_script: bool, ?scopes: Array[Array[Symbol]], ?version: String) -> Array[Comment]
+  #    def self.parse_success?:      (String source,  ?filepath: String, ?command_line: String, ?encoding: Encoding | false, ?freeze: bool, ?frozen_string_literal: bool, ?line: Integer, ?main_script: bool, ?partial_script: bool, ?scopes: Array[Array[Symbol]], ?version: String) -> bool
+  #    def self.parse_failure?:      (String source,  ?filepath: String, ?command_line: String, ?encoding: Encoding | false, ?freeze: bool, ?frozen_string_literal: bool, ?line: Integer, ?main_script: bool, ?partial_script: bool, ?scopes: Array[Array[Symbol]], ?version: String) -> bool
+  #    def self.parse_stream:        (_Stream stream, ?filepath: String, ?command_line: String, ?encoding: Encoding | false, ?freeze: bool, ?frozen_string_literal: bool, ?line: Integer, ?main_script: bool, ?partial_script: bool, ?scopes: Array[Array[Symbol]], ?version: String) -> ParseResult
+  #    def self.parse_file:          (String filepath,                   ?command_line: String, ?encoding: Encoding | false, ?freeze: bool, ?frozen_string_literal: bool, ?line: Integer, ?main_script: bool, ?partial_script: bool, ?scopes: Array[Array[Symbol]], ?version: String) -> ParseResult
+  #    def self.profile_file:        (String filepath,                   ?command_line: String, ?encoding: Encoding | false, ?freeze: bool, ?frozen_string_literal: bool, ?line: Integer, ?main_script: bool, ?partial_script: bool, ?scopes: Array[Array[Symbol]], ?version: String) -> void
+  #    def self.lex_file:            (String filepath,                   ?command_line: String, ?encoding: Encoding | false, ?freeze: bool, ?frozen_string_literal: bool, ?line: Integer, ?main_script: bool, ?partial_script: bool, ?scopes: Array[Array[Symbol]], ?version: String) -> LexResult
+  #    def self.parse_lex_file:      (String filepath,                   ?command_line: String, ?encoding: Encoding | false, ?freeze: bool, ?frozen_string_literal: bool, ?line: Integer, ?main_script: bool, ?partial_script: bool, ?scopes: Array[Array[Symbol]], ?version: String) -> ParseLexResult
+  #    def self.dump_file:           (String filepath,                   ?command_line: String, ?encoding: Encoding | false, ?freeze: bool, ?frozen_string_literal: bool, ?line: Integer, ?main_script: bool, ?partial_script: bool, ?scopes: Array[Array[Symbol]], ?version: String) -> String
+  #    def self.parse_file_comments: (String filepath,                   ?command_line: String, ?encoding: Encoding | false, ?freeze: bool, ?frozen_string_literal: bool, ?line: Integer, ?main_script: bool, ?partial_script: bool, ?scopes: Array[Array[Symbol]], ?version: String) -> Array[Comment]
+  #    def self.parse_file_success?: (String filepath,                   ?command_line: String, ?encoding: Encoding | false, ?freeze: bool, ?frozen_string_literal: bool, ?line: Integer, ?main_script: bool, ?partial_script: bool, ?scopes: Array[Array[Symbol]], ?version: String) -> bool
+  #    def self.parse_file_failure?: (String filepath,                   ?command_line: String, ?encoding: Encoding | false, ?freeze: bool, ?frozen_string_literal: bool, ?line: Integer, ?main_script: bool, ?partial_script: bool, ?scopes: Array[Array[Symbol]], ?version: String) -> bool
+end
+
+require_relative "prism/polyfill/byteindex"
+require_relative "prism/polyfill/warn"
+require_relative "prism/node"
+require_relative "prism/node_ext"
+require_relative "prism/parse_result"
+
+# This is a Ruby implementation of the prism parser. If we're running on CRuby
+# and we haven't explicitly set the PRISM_FFI_BACKEND environment variable, then
+# it's going to require the built library. Otherwise, it's going to require a
+# module that uses FFI to call into the library.
+if RUBY_ENGINE == "ruby" and !ENV["PRISM_FFI_BACKEND"]
+  # The C extension is the default backend on CRuby.
+  Prism::BACKEND = :CEXT
+
+  require "prism/prism"
+else
+  # The FFI backend is used on other Ruby implementations.
+  Prism::BACKEND = :FFI
+
+  require_relative "prism/ffi"
+end
diff --git a/lib/prism/desugar_compiler.rb b/lib/prism/desugar_compiler.rb
new file mode 100644
index 0000000000..c64d03f64a
--- /dev/null
+++ b/lib/prism/desugar_compiler.rb
@@ -0,0 +1,463 @@
+# frozen_string_literal: true
+# :markup: markdown
+#--
+# rbs_inline: enabled
+
+module Prism
+  class DesugarAndWriteNode # :nodoc:
+    include DSL
+
+    attr_reader :node #: ClassVariableAndWriteNode | ConstantAndWriteNode | GlobalVariableAndWriteNode | InstanceVariableAndWriteNode | LocalVariableAndWriteNode
+    attr_reader :default_source #: Source
+    attr_reader :read_class, :write_class #: Symbol
+    attr_reader :arguments #: Hash[Symbol, untyped]
+
+    #: ((ClassVariableAndWriteNode | ConstantAndWriteNode | GlobalVariableAndWriteNode | InstanceVariableAndWriteNode | LocalVariableAndWriteNode) node, Source default_source, Symbol read_class, Symbol write_class, **untyped arguments) -> void
+    def initialize(node, default_source, read_class, write_class, **arguments)
+      @node = node
+      @default_source = default_source
+      @read_class = read_class
+      @write_class = write_class
+      @arguments = arguments
+    end
+
+    # Desugar `x &&= y` to `x && x = y`
+    #--
+    #: () -> node
+    def compile
+      and_node(
+        location: node.location,
+        left: public_send(read_class, location: node.name_loc, **arguments),
+        right: public_send(
+          write_class,
+          location: node.location,
+          **arguments,
+          name_loc: node.name_loc,
+          value: node.value,
+          operator_loc: node.operator_loc
+        ),
+        operator_loc: node.operator_loc
+      )
+    end
+  end
+
+  class DesugarOrWriteDefinedNode # :nodoc:
+    include DSL
+
+    attr_reader :node #: ClassVariableOrWriteNode | ConstantOrWriteNode | GlobalVariableOrWriteNode
+    attr_reader :default_source #: Source
+    attr_reader :read_class, :write_class #: Symbol
+    attr_reader :arguments #: Hash[Symbol, untyped]
+
+    #: ((ClassVariableOrWriteNode | ConstantOrWriteNode | GlobalVariableOrWriteNode) node, Source default_source, Symbol read_class, Symbol write_class, **untyped arguments) -> void
+    def initialize(node, default_source, read_class, write_class, **arguments)
+      @node = node
+      @default_source = default_source
+      @read_class = read_class
+      @write_class = write_class
+      @arguments = arguments
+    end
+
+    # Desugar `x ||= y` to `defined?(x) ? x : x = y`
+    #--
+    #: () -> node
+    def compile
+      if_node(
+        location: node.location,
+        if_keyword_loc: node.operator_loc,
+        predicate: defined_node(
+          location: node.name_loc,
+          value: public_send(read_class, location: node.name_loc, **arguments),
+          keyword_loc: node.operator_loc
+        ),
+        then_keyword_loc: node.operator_loc,
+        statements: statements_node(
+          location: node.location,
+          body: [public_send(read_class, location: node.name_loc, **arguments)]
+        ),
+        subsequent: else_node(
+          location: node.location,
+          else_keyword_loc: node.operator_loc,
+          statements: statements_node(
+            location: node.location,
+            body: [
+              public_send(
+                write_class,
+                location: node.location,
+                **arguments,
+                name_loc: node.name_loc,
+                value: node.value,
+                operator_loc: node.operator_loc
+              )
+            ]
+          ),
+          end_keyword_loc: node.operator_loc
+        ),
+        end_keyword_loc: node.operator_loc
+      )
+    end
+  end
+
+  class DesugarOperatorWriteNode # :nodoc:
+    include DSL
+
+    attr_reader :node #: ClassVariableOperatorWriteNode | ConstantOperatorWriteNode | GlobalVariableOperatorWriteNode | InstanceVariableOperatorWriteNode | LocalVariableOperatorWriteNode
+    attr_reader :default_source #: Source
+    attr_reader :read_class, :write_class #: Symbol
+    attr_reader :arguments #: Hash[Symbol, untyped]
+
+    #: ((ClassVariableOperatorWriteNode | ConstantOperatorWriteNode | GlobalVariableOperatorWriteNode | InstanceVariableOperatorWriteNode | LocalVariableOperatorWriteNode) node, Source default_source, Symbol read_class, Symbol write_class, **untyped arguments) -> void
+    def initialize(node, default_source, read_class, write_class, **arguments)
+      @node = node
+      @default_source = default_source
+      @read_class = read_class
+      @write_class = write_class
+      @arguments = arguments
+    end
+
+    # Desugar `x += y` to `x = x + y`
+    #--
+    #: () -> node
+    def compile
+      binary_operator_loc = node.binary_operator_loc.chop
+
+      public_send(
+        write_class,
+        location: node.location,
+        **arguments,
+        name_loc: node.name_loc,
+        value: call_node(
+          location: node.location,
+          receiver: public_send(
+            read_class,
+            location: node.name_loc,
+            **arguments
+          ),
+          name: binary_operator_loc.slice.to_sym,
+          message_loc: binary_operator_loc,
+          arguments: arguments_node(
+            location: node.value.location,
+            arguments: [node.value]
+          )
+        ),
+        operator_loc: node.binary_operator_loc.copy(
+          start_offset: node.binary_operator_loc.end_offset - 1,
+          length: 1
+        )
+      )
+    end
+  end
+
+  class DesugarOrWriteNode # :nodoc:
+    include DSL
+
+    attr_reader :node #: InstanceVariableOrWriteNode | LocalVariableOrWriteNode
+    attr_reader :default_source #: Source
+    attr_reader :read_class, :write_class #: Symbol
+    attr_reader :arguments #: Hash[Symbol, untyped]
+
+    #: ((InstanceVariableOrWriteNode | LocalVariableOrWriteNode) node, Source default_source, Symbol read_class, Symbol write_class, **untyped arguments) -> void
+    def initialize(node, default_source, read_class, write_class, **arguments)
+      @node = node
+      @default_source = default_source
+      @read_class = read_class
+      @write_class = write_class
+      @arguments = arguments
+    end
+
+    # Desugar `x ||= y` to `x || x = y`
+    #--
+    #: () -> node
+    def compile
+      or_node(
+        location: node.location,
+        left: public_send(read_class, location: node.name_loc, **arguments),
+        right: public_send(
+          write_class,
+          location: node.location,
+          **arguments,
+          name_loc: node.name_loc,
+          value: node.value,
+          operator_loc: node.operator_loc
+        ),
+        operator_loc: node.operator_loc
+      )
+    end
+  end
+
+  private_constant :DesugarAndWriteNode, :DesugarOrWriteNode, :DesugarOrWriteDefinedNode, :DesugarOperatorWriteNode
+
+  class ClassVariableAndWriteNode
+    #: () -> node
+    def desugar # :nodoc:
+      DesugarAndWriteNode.new(self, source, :class_variable_read_node, :class_variable_write_node, name: name).compile
+    end
+  end
+
+  class ClassVariableOrWriteNode
+    #: () -> node
+    def desugar # :nodoc:
+      DesugarOrWriteDefinedNode.new(self, source, :class_variable_read_node, :class_variable_write_node, name: name).compile
+    end
+  end
+
+  class ClassVariableOperatorWriteNode
+    #: () -> node
+    def desugar # :nodoc:
+      DesugarOperatorWriteNode.new(self, source, :class_variable_read_node, :class_variable_write_node, name: name).compile
+    end
+  end
+
+  class ConstantAndWriteNode
+    #: () -> node
+    def desugar # :nodoc:
+      DesugarAndWriteNode.new(self, source, :constant_read_node, :constant_write_node, name: name).compile
+    end
+  end
+
+  class ConstantOrWriteNode
+    #: () -> node
+    def desugar # :nodoc:
+      DesugarOrWriteDefinedNode.new(self, source, :constant_read_node, :constant_write_node, name: name).compile
+    end
+  end
+
+  class ConstantOperatorWriteNode
+    #: () -> node
+    def desugar # :nodoc:
+      DesugarOperatorWriteNode.new(self, source, :constant_read_node, :constant_write_node, name: name).compile
+    end
+  end
+
+  class GlobalVariableAndWriteNode
+    #: () -> node
+    def desugar # :nodoc:
+      DesugarAndWriteNode.new(self, source, :global_variable_read_node, :global_variable_write_node, name: name).compile
+    end
+  end
+
+  class GlobalVariableOrWriteNode
+    #: () -> node
+    def desugar # :nodoc:
+      DesugarOrWriteDefinedNode.new(self, source, :global_variable_read_node, :global_variable_write_node, name: name).compile
+    end
+  end
+
+  class GlobalVariableOperatorWriteNode
+    #: () -> node
+    def desugar # :nodoc:
+      DesugarOperatorWriteNode.new(self, source, :global_variable_read_node, :global_variable_write_node, name: name).compile
+    end
+  end
+
+  class InstanceVariableAndWriteNode
+    #: () -> node
+    def desugar # :nodoc:
+      DesugarAndWriteNode.new(self, source, :instance_variable_read_node, :instance_variable_write_node, name: name).compile
+    end
+  end
+
+  class InstanceVariableOrWriteNode
+    #: () -> node
+    def desugar # :nodoc:
+      DesugarOrWriteNode.new(self, source, :instance_variable_read_node, :instance_variable_write_node, name: name).compile
+    end
+  end
+
+  class InstanceVariableOperatorWriteNode
+    #: () -> node
+    def desugar # :nodoc:
+      DesugarOperatorWriteNode.new(self, source, :instance_variable_read_node, :instance_variable_write_node, name: name).compile
+    end
+  end
+
+  class LocalVariableAndWriteNode
+    #: () -> node
+    def desugar # :nodoc:
+      DesugarAndWriteNode.new(self, source, :local_variable_read_node, :local_variable_write_node, name: name, depth: depth).compile
+    end
+  end
+
+  class LocalVariableOrWriteNode
+    #: () -> node
+    def desugar # :nodoc:
+      DesugarOrWriteNode.new(self, source, :local_variable_read_node, :local_variable_write_node, name: name, depth: depth).compile
+    end
+  end
+
+  class LocalVariableOperatorWriteNode
+    #: () -> node
+    def desugar # :nodoc:
+      DesugarOperatorWriteNode.new(self, source, :local_variable_read_node, :local_variable_write_node, name: name, depth: depth).compile
+    end
+  end
+
+  # DesugarCompiler is a compiler that desugars Ruby code into a more primitive
+  # form. This is useful for consumers that want to deal with fewer node types.
+  class DesugarCompiler < MutationCompiler
+    # `@@foo &&= bar`
+    #
+    # becomes
+    #
+    # `@@foo && @@foo = bar`
+    #--
+    #: (ClassVariableAndWriteNode node) -> node
+    def visit_class_variable_and_write_node(node)
+      node.desugar
+    end
+
+    # `@@foo ||= bar`
+    #
+    # becomes
+    #
+    # `defined?(@@foo) ? @@foo : @@foo = bar`
+    #--
+    #: (ClassVariableOrWriteNode node) -> node
+    def visit_class_variable_or_write_node(node)
+      node.desugar
+    end
+
+    # `@@foo += bar`
+    #
+    # becomes
+    #
+    # `@@foo = @@foo + bar`
+    #--
+    #: (ClassVariableOperatorWriteNode node) -> node
+    def visit_class_variable_operator_write_node(node)
+      node.desugar
+    end
+
+    # `Foo &&= bar`
+    #
+    # becomes
+    #
+    # `Foo && Foo = bar`
+    #--
+    #: (ConstantAndWriteNode node) -> node
+    def visit_constant_and_write_node(node)
+      node.desugar
+    end
+
+    # `Foo ||= bar`
+    #
+    # becomes
+    #
+    # `defined?(Foo) ? Foo : Foo = bar`
+    #--
+    #: (ConstantOrWriteNode node) -> node
+    def visit_constant_or_write_node(node)
+      node.desugar
+    end
+
+    # `Foo += bar`
+    #
+    # becomes
+    #
+    # `Foo = Foo + bar`
+    #--
+    #: (ConstantOperatorWriteNode node) -> node
+    def visit_constant_operator_write_node(node)
+      node.desugar
+    end
+
+    # `$foo &&= bar`
+    #
+    # becomes
+    #
+    # `$foo && $foo = bar`
+    #--
+    #: (GlobalVariableAndWriteNode node) -> node
+    def visit_global_variable_and_write_node(node)
+      node.desugar
+    end
+
+    # `$foo ||= bar`
+    #
+    # becomes
+    #
+    # `defined?($foo) ? $foo : $foo = bar`
+    #--
+    #: (GlobalVariableOrWriteNode node) -> node
+    def visit_global_variable_or_write_node(node)
+      node.desugar
+    end
+
+    # `$foo += bar`
+    #
+    # becomes
+    #
+    # `$foo = $foo + bar`
+    #--
+    #: (GlobalVariableOperatorWriteNode node) -> node
+    def visit_global_variable_operator_write_node(node)
+      node.desugar
+    end
+
+    # `@foo &&= bar`
+    #
+    # becomes
+    #
+    # `@foo && @foo = bar`
+    #--
+    #: (InstanceVariableAndWriteNode node) -> node
+    def visit_instance_variable_and_write_node(node)
+      node.desugar
+    end
+
+    # `@foo ||= bar`
+    #
+    # becomes
+    #
+    # `@foo || @foo = bar`
+    #--
+    #: (InstanceVariableOrWriteNode node) -> node
+    def visit_instance_variable_or_write_node(node)
+      node.desugar
+    end
+
+    # `@foo += bar`
+    #
+    # becomes
+    #
+    # `@foo = @foo + bar`
+    #--
+    #: (InstanceVariableOperatorWriteNode node) -> node
+    def visit_instance_variable_operator_write_node(node)
+      node.desugar
+    end
+
+    # `foo &&= bar`
+    #
+    # becomes
+    #
+    # `foo && foo = bar`
+    #--
+    #: (LocalVariableAndWriteNode node) -> node
+    def visit_local_variable_and_write_node(node)
+      node.desugar
+    end
+
+    # `foo ||= bar`
+    #
+    # becomes
+    #
+    # `foo || foo = bar`
+    #--
+    #: (LocalVariableOrWriteNode node) -> node
+    def visit_local_variable_or_write_node(node)
+      node.desugar
+    end
+
+    # `foo += bar`
+    #
+    # becomes
+    #
+    # `foo = foo + bar`
+    #--
+    #: (LocalVariableOperatorWriteNode node) -> node
+    def visit_local_variable_operator_write_node(node)
+      node.desugar
+    end
+  end
+end
diff --git a/lib/prism/ffi.rb b/lib/prism/ffi.rb
new file mode 100644
index 0000000000..6b9bde51ea
--- /dev/null
+++ b/lib/prism/ffi.rb
@@ -0,0 +1,611 @@
+# frozen_string_literal: true
+# :markup: markdown
+# typed: ignore
+
+# This file is responsible for mirroring the API provided by the C extension by
+# using FFI to call into the shared library.
+
+require "rbconfig"
+require "ffi"
+
+# We want to eagerly load this file if there are Ractors so that it does not get
+# autoloaded from within a non-main Ractor.
+require "prism/serialize" if defined?(Ractor)
+
+module Prism # :nodoc:
+  module LibRubyParser # :nodoc:
+    extend FFI::Library
+
+    # Define the library that we will be pulling functions from. Note that this
+    # must align with the build shared library from make/rake.
+    libprism_in_build = File.expand_path("../../build/libprism.#{RbConfig::CONFIG["SOEXT"]}", __dir__)
+    libprism_in_libdir = "#{RbConfig::CONFIG["libdir"]}/prism/libprism.#{RbConfig::CONFIG["SOEXT"]}"
+
+    if File.exist?(libprism_in_build)
+      INCLUDE_DIR = File.expand_path("../../include", __dir__)
+      ffi_lib libprism_in_build
+    else
+      INCLUDE_DIR = "#{RbConfig::CONFIG["libdir"]}/prism/include"
+      ffi_lib libprism_in_libdir
+    end
+
+    # Convert a native C type declaration into a symbol that FFI understands.
+    # For example:
+    #
+    #     const char * -> :pointer
+    #     bool         -> :bool
+    #     size_t       -> :size_t
+    #     void         -> :void
+    #
+    def self.resolve_type(type, callbacks)
+      type = type.strip
+
+      if !type.end_with?("*")
+        type.delete_prefix("const ").to_sym
+      else
+        type = type.delete_suffix("*").rstrip
+        callbacks.include?(type.to_sym) ? type.to_sym : :pointer
+      end
+    end
+
+    # Read through the given header file and find the declaration of each of the
+    # given functions. For each one, define a function with the same name and
+    # signature as the C function.
+    def self.load_exported_functions_from(header, *functions, callbacks)
+      File.foreach("#{INCLUDE_DIR}/#{header}") do |line|
+        # We only want to attempt to load exported functions.
+        next unless line.start_with?("PRISM_EXPORTED_FUNCTION ")
+
+        # We only want to load the functions that we are interested in.
+        next unless functions.any? { |function| line.include?(function) }
+
+        # Strip trailing attributes (PRISM_NODISCARD, PRISM_NONNULL(...), etc.)
+        line = line.sub(/\)(\s+PRISM_\w+(?:\([^)]*\))?)+\s*;/, ");")
+
+        # Parse the function declaration.
+        unless /^PRISM_EXPORTED_FUNCTION (?<return_type>.+) (?<name>\w+)\((?<arg_types>.+)\);$/ =~ line
+          raise "Could not parse #{line}"
+        end
+
+        # Delete the function from the list of functions we are looking for to
+        # mark it as having been found.
+        functions.delete(name)
+
+        # Split up the argument types into an array, ensure we handle the case
+        # where there are no arguments (by explicit void).
+        arg_types = arg_types.split(",").map(&:strip)
+        arg_types = [] if arg_types == %w[void]
+
+        # Resolve the type of the argument by dropping the name of the argument
+        # first if it is present.
+        arg_types.map! { |type| resolve_type(type.sub(/\w+$/, ""), callbacks) }
+
+        # Attach the function using the FFI library.
+        attach_function name, arg_types, resolve_type(return_type, [])
+      end
+
+      # If we didn't find all of the functions, raise an error.
+      raise "Could not find functions #{functions.inspect}" unless functions.empty?
+    end
+
+    callback :pm_source_stream_fgets_t, [:pointer, :int, :pointer], :pointer
+    callback :pm_source_stream_feof_t, [:pointer], :int
+    pm_source_init_result_values = %i[PM_SOURCE_INIT_SUCCESS PM_SOURCE_INIT_ERROR_GENERIC PM_SOURCE_INIT_ERROR_DIRECTORY PM_SOURCE_INIT_ERROR_NON_REGULAR]
+    enum :pm_source_init_result_t, pm_source_init_result_values
+    enum :pm_string_query_t, [:PM_STRING_QUERY_ERROR, -1, :PM_STRING_QUERY_FALSE, :PM_STRING_QUERY_TRUE]
+
+    # Ractor-safe lookup table for pm_source_init_result_t, since FFI's
+    # enum_type accesses module instance variables that are not shareable.
+    SOURCE_INIT_RESULT = pm_source_init_result_values.freeze
+
+    load_exported_functions_from(
+      "prism/version.h",
+      "pm_version",
+      []
+    )
+
+    load_exported_functions_from(
+      "prism/serialize.h",
+      "pm_serialize_parse",
+      "pm_serialize_parse_stream",
+      "pm_serialize_parse_comments",
+      "pm_serialize_lex",
+      "pm_serialize_parse_lex",
+      "pm_serialize_parse_success_p",
+      []
+    )
+
+    load_exported_functions_from(
+      "prism/string_query.h",
+      "pm_string_query_local",
+      "pm_string_query_constant",
+      "pm_string_query_method_name",
+      []
+    )
+
+    load_exported_functions_from(
+      "prism/buffer.h",
+      "pm_buffer_new",
+      "pm_buffer_value",
+      "pm_buffer_length",
+      "pm_buffer_free",
+      []
+    )
+
+    load_exported_functions_from(
+      "prism/source.h",
+      "pm_source_file_new",
+      "pm_source_mapped_new",
+      "pm_source_stream_new",
+      "pm_source_free",
+      "pm_source_source",
+      "pm_source_length",
+      [:pm_source_stream_fgets_t, :pm_source_stream_feof_t]
+    )
+
+    # This object represents a pm_buffer_t. We only use it as an opaque pointer,
+    # so it doesn't need to know the fields of pm_buffer_t.
+    class PrismBuffer # :nodoc:
+      attr_reader :pointer
+
+      def initialize(pointer)
+        @pointer = pointer
+      end
+
+      def value
+        LibRubyParser.pm_buffer_value(pointer)
+      end
+
+      def length
+        LibRubyParser.pm_buffer_length(pointer)
+      end
+
+      def read
+        value.read_string(length)
+      end
+
+      # Initialize a new buffer and yield it to the block. The buffer will be
+      # automatically freed when the block returns.
+      def self.with
+        buffer = LibRubyParser.pm_buffer_new
+        raise unless buffer
+
+        begin
+          yield new(buffer)
+        ensure
+          LibRubyParser.pm_buffer_free(buffer)
+        end
+      end
+    end
+
+    # This object represents source code to be parsed. For strings it wraps a
+    # pointer directly; for files it uses a pm_source_t under the hood.
+    class PrismSource # :nodoc:
+      PLATFORM_EXPECTS_UTF8 =
+        RbConfig::CONFIG["host_os"].match?(/bccwin|cygwin|djgpp|mingw|mswin|wince|darwin/i)
+
+      attr_reader :pointer, :length
+
+      def initialize(pointer, length, from_string)
+        @pointer = pointer
+        @length = length
+        @from_string = from_string
+      end
+
+      def read
+        raise "should use the original String instead" if @from_string
+        @pointer.read_string(@length)
+      end
+
+      # Yields a PrismSource backed by the given string to the block.
+      def self.with_string(string)
+        raise TypeError unless string.is_a?(String)
+
+        length = string.bytesize
+        # + 1 to never get an address of 0, which pm_parser_init() asserts
+        FFI::MemoryPointer.new(:char, length + 1, false) do |pointer|
+          pointer.write_string(string)
+          # since we have the extra byte we might as well \0-terminate
+          pointer.put_char(length, 0)
+          return yield new(pointer, length, true)
+        end
+      end
+
+      # Yields a PrismSource to the given block, backed by a pm_source_t.
+      def self.with_file(filepath)
+        raise TypeError unless filepath.is_a?(String)
+
+        # On Windows and Mac, it's expected that filepaths will be encoded in
+        # UTF-8. If they are not, we need to convert them to UTF-8 before
+        # passing them into pm_source_mapped_new.
+        if PLATFORM_EXPECTS_UTF8 && (encoding = filepath.encoding) != Encoding::ASCII_8BIT && encoding != Encoding::UTF_8
+          filepath = filepath.encode(Encoding::UTF_8)
+        end
+
+        FFI::MemoryPointer.new(:int) do |result_ptr|
+          pm_source = LibRubyParser.pm_source_mapped_new(filepath, 0, result_ptr)
+
+          case SOURCE_INIT_RESULT[result_ptr.read_int]
+          when :PM_SOURCE_INIT_SUCCESS
+            pointer = LibRubyParser.pm_source_source(pm_source)
+            length = LibRubyParser.pm_source_length(pm_source)
+            return yield new(pointer, length, false)
+          when :PM_SOURCE_INIT_ERROR_GENERIC
+            raise SystemCallError.new(filepath, FFI.errno)
+          when :PM_SOURCE_INIT_ERROR_DIRECTORY
+            raise Errno::EISDIR.new(filepath)
+          when :PM_SOURCE_INIT_ERROR_NON_REGULAR
+            # Fall back to reading the file through Ruby IO for non-regular
+            # files (pipes, character devices, etc.)
+            return with_string(File.read(filepath)) { |string| yield string }
+          else
+            raise "Unknown error initializing pm_source_t: #{result_ptr.read_int}"
+          end
+        ensure
+          LibRubyParser.pm_source_free(pm_source) if pm_source && !pm_source.null?
+        end
+      end
+    end
+  end
+
+  # Mark the LibRubyParser module as private as it should only be called through
+  # the prism module.
+  private_constant :LibRubyParser
+
+  # The version constant is set by reading the result of calling pm_version.
+  VERSION = LibRubyParser.pm_version.read_string.freeze
+
+  class << self
+    # Mirror the Prism.dump API by using the serialization API.
+    def dump(source, **options)
+      LibRubyParser::PrismSource.with_string(source) { |string| dump_common(string, options) }
+    end
+
+    # Mirror the Prism.dump_file API by using the serialization API.
+    def dump_file(filepath, **options)
+      options[:filepath] = filepath
+      LibRubyParser::PrismSource.with_file(filepath) { |string| dump_common(string, options) }
+    end
+
+    # Mirror the Prism.lex API by using the serialization API.
+    def lex(code, **options)
+      LibRubyParser::PrismSource.with_string(code) { |string| lex_common(string, code, options) }
+    end
+
+    # Mirror the Prism.lex_file API by using the serialization API.
+    def lex_file(filepath, **options)
+      options[:filepath] = filepath
+      LibRubyParser::PrismSource.with_file(filepath) { |string| lex_common(string, string.read, options) }
+    end
+
+    # Mirror the Prism.parse API by using the serialization API.
+    def parse(code, **options)
+      LibRubyParser::PrismSource.with_string(code) { |string| parse_common(string, code, options) }
+    end
+
+    # Mirror the Prism.parse_file API by using the serialization API. This uses
+    # native strings instead of Ruby strings because it allows us to use mmap
+    # when it is available.
+    def parse_file(filepath, **options)
+      options[:filepath] = filepath
+      LibRubyParser::PrismSource.with_file(filepath) { |string| parse_common(string, string.read, options) }
+    end
+
+    # Mirror the Prism.parse_stream API by using the serialization API.
+    def parse_stream(stream, **options)
+      LibRubyParser::PrismBuffer.with do |buffer|
+        source = +""
+        callback = -> (string, size, _) {
+          raise "Expected size to be >= 0, got: #{size}" if size <= 0
+
+          if !(line = stream.gets(size - 1)).nil?
+            source << line
+            string.write_string("#{line}\x00", line.bytesize + 1)
+          end
+        }
+
+        eof_callback = -> (_) { stream.eof?  }
+
+        pm_source = LibRubyParser.pm_source_stream_new(nil, callback, eof_callback)
+        begin
+          LibRubyParser.pm_serialize_parse_stream(buffer.pointer, pm_source, dump_options(options))
+          Prism.load(source, buffer.read, options.fetch(:freeze, false))
+        ensure
+          LibRubyParser.pm_source_free(pm_source) if pm_source && !pm_source.null?
+        end
+      end
+    end
+
+    # Mirror the Prism.parse_comments API by using the serialization API.
+    def parse_comments(code, **options)
+      LibRubyParser::PrismSource.with_string(code) { |string| parse_comments_common(string, code, options) }
+    end
+
+    # Mirror the Prism.parse_file_comments API by using the serialization
+    # API. This uses native strings instead of Ruby strings because it allows us
+    # to use mmap when it is available.
+    def parse_file_comments(filepath, **options)
+      options[:filepath] = filepath
+      LibRubyParser::PrismSource.with_file(filepath) { |string| parse_comments_common(string, string.read, options) }
+    end
+
+    # Mirror the Prism.parse_lex API by using the serialization API.
+    def parse_lex(code, **options)
+      LibRubyParser::PrismSource.with_string(code) { |string| parse_lex_common(string, code, options) }
+    end
+
+    # Mirror the Prism.parse_lex_file API by using the serialization API.
+    def parse_lex_file(filepath, **options)
+      options[:filepath] = filepath
+      LibRubyParser::PrismSource.with_file(filepath) { |string| parse_lex_common(string, string.read, options) }
+    end
+
+    # Mirror the Prism.parse_success? API by using the serialization API.
+    def parse_success?(code, **options)
+      LibRubyParser::PrismSource.with_string(code) { |string| parse_file_success_common(string, options) }
+    end
+
+    # Mirror the Prism.parse_failure? API by using the serialization API.
+    def parse_failure?(code, **options)
+      !parse_success?(code, **options)
+    end
+
+    # Mirror the Prism.parse_file_success? API by using the serialization API.
+    def parse_file_success?(filepath, **options)
+      options[:filepath] = filepath
+      LibRubyParser::PrismSource.with_file(filepath) { |string| parse_file_success_common(string, options) }
+    end
+
+    # Mirror the Prism.parse_file_failure? API by using the serialization API.
+    def parse_file_failure?(filepath, **options)
+      !parse_file_success?(filepath, **options)
+    end
+
+    # Mirror the Prism.profile API by using the serialization API.
+    def profile(source, **options)
+      LibRubyParser::PrismSource.with_string(source) do |string|
+        LibRubyParser::PrismBuffer.with do |buffer|
+          LibRubyParser.pm_serialize_parse(buffer.pointer, string.pointer, string.length, dump_options(options))
+          nil
+        end
+      end
+    end
+
+    # Mirror the Prism.profile_file API by using the serialization API.
+    def profile_file(filepath, **options)
+      LibRubyParser::PrismSource.with_file(filepath) do |string|
+        LibRubyParser::PrismBuffer.with do |buffer|
+          options[:filepath] = filepath
+          LibRubyParser.pm_serialize_parse(buffer.pointer, string.pointer, string.length, dump_options(options))
+          nil
+        end
+      end
+    end
+
+    private
+
+    def dump_common(string, options) # :nodoc:
+      LibRubyParser::PrismBuffer.with do |buffer|
+        LibRubyParser.pm_serialize_parse(buffer.pointer, string.pointer, string.length, dump_options(options))
+
+        dumped = buffer.read
+        dumped.freeze if options.fetch(:freeze, false)
+
+        dumped
+      end
+    end
+
+    def lex_common(string, code, options) # :nodoc:
+      LibRubyParser::PrismBuffer.with do |buffer|
+        LibRubyParser.pm_serialize_lex(buffer.pointer, string.pointer, string.length, dump_options(options))
+        Serialize.load_lex(code, buffer.read, options.fetch(:freeze, false))
+      end
+    end
+
+    def parse_common(string, code, options) # :nodoc:
+      serialized = dump_common(string, options)
+      Serialize.load_parse(code, serialized, options.fetch(:freeze, false))
+    end
+
+    def parse_comments_common(string, code, options) # :nodoc:
+      LibRubyParser::PrismBuffer.with do |buffer|
+        LibRubyParser.pm_serialize_parse_comments(buffer.pointer, string.pointer, string.length, dump_options(options))
+        Serialize.load_parse_comments(code, buffer.read, options.fetch(:freeze, false))
+      end
+    end
+
+    def parse_lex_common(string, code, options) # :nodoc:
+      LibRubyParser::PrismBuffer.with do |buffer|
+        LibRubyParser.pm_serialize_parse_lex(buffer.pointer, string.pointer, string.length, dump_options(options))
+        Serialize.load_parse_lex(code, buffer.read, options.fetch(:freeze, false))
+      end
+    end
+
+    def parse_file_success_common(string, options) # :nodoc:
+      LibRubyParser.pm_serialize_parse_success_p(string.pointer, string.length, dump_options(options))
+    end
+
+    # Return the value that should be dumped for the command_line option.
+    def dump_options_command_line(options)
+      command_line = options.fetch(:command_line, "")
+      raise ArgumentError, "command_line must be a string" unless command_line.is_a?(String)
+
+      command_line.each_char.inject(0) do |value, char|
+        case char
+        when "a" then value | 0b000001
+        when "e" then value | 0b000010
+        when "l" then value | 0b000100
+        when "n" then value | 0b001000
+        when "p" then value | 0b010000
+        when "x" then value | 0b100000
+        else raise ArgumentError, "invalid command_line option: #{char}"
+        end
+      end
+    end
+
+    # Return the value that should be dumped for the version option.
+    def dump_options_version(version)
+      case version
+      when "current"
+        version_string_to_number(RUBY_VERSION) || raise(CurrentVersionError, RUBY_VERSION)
+      when "latest", nil
+        0 # Handled in pm_parser_init
+      when "nearest"
+        dump = version_string_to_number(RUBY_VERSION)
+        return dump if dump
+        if RUBY_VERSION < "3.3"
+          version_string_to_number("3.3")
+        else
+          0 # Handled in pm_parser_init
+        end
+      else
+        version_string_to_number(version) || raise(ArgumentError, "invalid version: #{version}")
+      end
+    end
+
+    # Converts a version string like "4.0.0" or "4.0" into a number.
+    # Returns nil if the version is unknown.
+    def version_string_to_number(version)
+      case version
+      when /\A3\.3(\.\d+)?\z/
+        1
+      when /\A3\.4(\.\d+)?\z/
+        2
+      when /\A3\.5(\.\d+)?\z/, /\A4\.0(\.\d+)?\z/
+        3
+      when /\A4\.1(\.\d+)?\z/
+        4
+      end
+    end
+
+    # Convert the given options into a serialized options string.
+    def dump_options(options)
+      template = +""
+      values = []
+
+      template << "L"
+      if (filepath = options[:filepath])
+        values.push(filepath.bytesize, filepath.b)
+        template << "A*"
+      else
+        values << 0
+      end
+
+      template << "l"
+      values << options.fetch(:line, 1)
+
+      template << "L"
+      if (encoding = options[:encoding])
+        name = encoding.is_a?(Encoding) ? encoding.name : encoding
+        values.push(name.bytesize, name.b)
+        template << "A*"
+      else
+        values << 0
+      end
+
+      template << "C"
+      values << (options.fetch(:frozen_string_literal, false) ? 1 : 0)
+
+      template << "C"
+      values << dump_options_command_line(options)
+
+      template << "C"
+      values << dump_options_version(options[:version])
+
+      template << "C"
+      values << (options[:encoding] == false ? 1 : 0)
+
+      template << "C"
+      values << (options.fetch(:main_script, false) ? 1 : 0)
+
+      template << "C"
+      values << (options.fetch(:partial_script, false) ? 1 : 0)
+
+      template << "C"
+      values << (options.fetch(:freeze, false) ? 1 : 0)
+
+      template << "L"
+      if (scopes = options[:scopes])
+        values << scopes.length
+
+        scopes.each do |scope|
+          locals = nil
+          forwarding = 0
+
+          case scope
+          when Array
+            locals = scope
+          when Scope
+            locals = scope.locals
+
+            scope.forwarding.each do |forward|
+              case forward
+              when :*     then forwarding |= 0x1
+              when :**    then forwarding |= 0x2
+              when :&     then forwarding |= 0x4
+              when :"..." then forwarding |= 0x8
+              else raise ArgumentError, "invalid forwarding value: #{forward}"
+              end
+            end
+          else
+            raise TypeError, "wrong argument type #{scope.class.inspect} (expected Array or Prism::Scope)"
+          end
+
+          template << "L"
+          values << locals.length
+
+          template << "C"
+          values << forwarding
+
+          locals.each do |local|
+            name = local.name
+            template << "L"
+            values << name.bytesize
+
+            template << "A*"
+            values << name.b
+          end
+        end
+      else
+        values << 0
+      end
+
+      values.pack(template)
+    end
+  end
+
+  # Here we are going to patch StringQuery to put in the class-level methods so
+  # that it can maintain a consistent interface
+  class StringQuery # :nodoc:
+    class << self
+      # Mirrors the C extension's StringQuery::local? method.
+      def local?(string)
+        query(LibRubyParser.pm_string_query_local(string, string.bytesize, string.encoding.name))
+      end
+
+      # Mirrors the C extension's StringQuery::constant? method.
+      def constant?(string)
+        query(LibRubyParser.pm_string_query_constant(string, string.bytesize, string.encoding.name))
+      end
+
+      # Mirrors the C extension's StringQuery::method_name? method.
+      def method_name?(string)
+        query(LibRubyParser.pm_string_query_method_name(string, string.bytesize, string.encoding.name))
+      end
+
+      private
+
+      # Parse the enum result and return an appropriate boolean.
+      def query(result)
+        case result
+        when :PM_STRING_QUERY_ERROR
+          raise ArgumentError, "Invalid or non ascii-compatible encoding"
+        when :PM_STRING_QUERY_FALSE
+          false
+        when :PM_STRING_QUERY_TRUE
+          true
+        end
+      end
+    end
+  end
+end
diff --git a/lib/prism/lex_compat.rb b/lib/prism/lex_compat.rb
new file mode 100644
index 0000000000..7aacec037d
--- /dev/null
+++ b/lib/prism/lex_compat.rb
@@ -0,0 +1,906 @@
+# frozen_string_literal: true
+# :markup: markdown
+#--
+# rbs_inline: enabled
+
+module Prism
+  # @rbs!
+  #    module Translation
+  #      class Ripper
+  #        EXPR_NONE: Integer
+  #        EXPR_BEG: Integer
+  #        EXPR_MID: Integer
+  #        EXPR_END: Integer
+  #        EXPR_CLASS: Integer
+  #        EXPR_VALUE: Integer
+  #        EXPR_ARG: Integer
+  #        EXPR_CMDARG: Integer
+  #        EXPR_ENDARG: Integer
+  #        EXPR_ENDFN: Integer
+  #
+  #        class Lexer < Ripper
+  #          class State
+  #            def self.[]: (Integer value) -> State
+  #          end
+  #        end
+  #
+  #        class LineAndColumnCache
+  #          def initialize: (Source source) -> void
+  #
+  #          def line_and_column: (Integer byte_offset) -> [Integer, Integer]
+  #        end
+  #      end
+  #    end
+
+  # This class is responsible for lexing the source using prism and then
+  # converting those tokens to be compatible with Ripper. In the vast majority
+  # of cases, this is a one-to-one mapping of the token type. Everything else
+  # generally lines up. However, there are a few cases that require special
+  # handling.
+  class LexCompat # :nodoc:
+    # @rbs!
+    #    # A token produced by the Ripper lexer that Prism is replicating.
+    #    type lex_compat_token = [[Integer, Integer], Symbol, String, untyped]
+
+    # A result class specialized for holding tokens produced by the lexer.
+    class Result < Prism::Result
+      # The list of tokens that were produced by the lexer.
+      attr_reader :value #: Array[lex_compat_token]
+
+      # Create a new lex compat result object with the given values.
+      #--
+      #: (Array[lex_compat_token] value, Array[Comment] comments, Array[MagicComment] magic_comments, Location? data_loc, Array[ParseError] errors, Array[ParseWarning] warnings, bool continuable, Source source) -> void
+      def initialize(value, comments, magic_comments, data_loc, errors, warnings, continuable, source)
+        @value = value
+        super(comments, magic_comments, data_loc, errors, warnings, continuable, source)
+      end
+
+      # Implement the hash pattern matching interface for Result.
+      #--
+      #: (Array[Symbol]? keys) -> Hash[Symbol, untyped]
+      def deconstruct_keys(keys) # :nodoc:
+        super.merge!(value: value)
+      end
+    end
+
+    # This is a mapping of prism token types to Ripper token types. This is a
+    # many-to-one mapping because we split up our token types, whereas Ripper
+    # tends to group them.
+    RIPPER = {
+      AMPERSAND: :on_op,
+      AMPERSAND_AMPERSAND: :on_op,
+      AMPERSAND_AMPERSAND_EQUAL: :on_op,
+      AMPERSAND_DOT: :on_op,
+      AMPERSAND_EQUAL: :on_op,
+      BACK_REFERENCE: :on_backref,
+      BACKTICK: :on_backtick,
+      BANG: :on_op,
+      BANG_EQUAL: :on_op,
+      BANG_TILDE: :on_op,
+      BRACE_LEFT: :on_lbrace,
+      BRACE_RIGHT: :on_rbrace,
+      BRACKET_LEFT: :on_lbracket,
+      BRACKET_LEFT_ARRAY: :on_lbracket,
+      BRACKET_LEFT_RIGHT: :on_op,
+      BRACKET_LEFT_RIGHT_EQUAL: :on_op,
+      BRACKET_RIGHT: :on_rbracket,
+      CARET: :on_op,
+      CARET_EQUAL: :on_op,
+      CHARACTER_LITERAL: :on_CHAR,
+      CLASS_VARIABLE: :on_cvar,
+      COLON: :on_op,
+      COLON_COLON: :on_op,
+      COMMA: :on_comma,
+      COMMENT: :on_comment,
+      CONSTANT: :on_const,
+      DOT: :on_period,
+      DOT_DOT: :on_op,
+      DOT_DOT_DOT: :on_op,
+      EMBDOC_BEGIN: :on_embdoc_beg,
+      EMBDOC_END: :on_embdoc_end,
+      EMBDOC_LINE: :on_embdoc,
+      EMBEXPR_BEGIN: :on_embexpr_beg,
+      EMBEXPR_END: :on_embexpr_end,
+      EMBVAR: :on_embvar,
+      EOF: :on_eof,
+      EQUAL: :on_op,
+      EQUAL_EQUAL: :on_op,
+      EQUAL_EQUAL_EQUAL: :on_op,
+      EQUAL_GREATER: :on_op,
+      EQUAL_TILDE: :on_op,
+      FLOAT: :on_float,
+      FLOAT_IMAGINARY: :on_imaginary,
+      FLOAT_RATIONAL: :on_rational,
+      FLOAT_RATIONAL_IMAGINARY: :on_imaginary,
+      GREATER: :on_op,
+      GREATER_EQUAL: :on_op,
+      GREATER_GREATER: :on_op,
+      GREATER_GREATER_EQUAL: :on_op,
+      GLOBAL_VARIABLE: :on_gvar,
+      HEREDOC_END: :on_heredoc_end,
+      HEREDOC_START: :on_heredoc_beg,
+      IDENTIFIER: :on_ident,
+      IGNORED_NEWLINE: :on_ignored_nl,
+      INTEGER: :on_int,
+      INTEGER_IMAGINARY: :on_imaginary,
+      INTEGER_RATIONAL: :on_rational,
+      INTEGER_RATIONAL_IMAGINARY: :on_imaginary,
+      INSTANCE_VARIABLE: :on_ivar,
+      INVALID: :INVALID,
+      KEYWORD___ENCODING__: :on_kw,
+      KEYWORD___LINE__: :on_kw,
+      KEYWORD___FILE__: :on_kw,
+      KEYWORD_ALIAS: :on_kw,
+      KEYWORD_AND: :on_kw,
+      KEYWORD_BEGIN: :on_kw,
+      KEYWORD_BEGIN_UPCASE: :on_kw,
+      KEYWORD_BREAK: :on_kw,
+      KEYWORD_CASE: :on_kw,
+      KEYWORD_CLASS: :on_kw,
+      KEYWORD_DEF: :on_kw,
+      KEYWORD_DEFINED: :on_kw,
+      KEYWORD_DO: :on_kw,
+      KEYWORD_DO_BLOCK: :on_kw,
+      KEYWORD_DO_LOOP: :on_kw,
+      KEYWORD_ELSE: :on_kw,
+      KEYWORD_ELSIF: :on_kw,
+      KEYWORD_END: :on_kw,
+      KEYWORD_END_UPCASE: :on_kw,
+      KEYWORD_ENSURE: :on_kw,
+      KEYWORD_FALSE: :on_kw,
+      KEYWORD_FOR: :on_kw,
+      KEYWORD_IF: :on_kw,
+      KEYWORD_IF_MODIFIER: :on_kw,
+      KEYWORD_IN: :on_kw,
+      KEYWORD_MODULE: :on_kw,
+      KEYWORD_NEXT: :on_kw,
+      KEYWORD_NIL: :on_kw,
+      KEYWORD_NOT: :on_kw,
+      KEYWORD_OR: :on_kw,
+      KEYWORD_REDO: :on_kw,
+      KEYWORD_RESCUE: :on_kw,
+      KEYWORD_RESCUE_MODIFIER: :on_kw,
+      KEYWORD_RETRY: :on_kw,
+      KEYWORD_RETURN: :on_kw,
+      KEYWORD_SELF: :on_kw,
+      KEYWORD_SUPER: :on_kw,
+      KEYWORD_THEN: :on_kw,
+      KEYWORD_TRUE: :on_kw,
+      KEYWORD_UNDEF: :on_kw,
+      KEYWORD_UNLESS: :on_kw,
+      KEYWORD_UNLESS_MODIFIER: :on_kw,
+      KEYWORD_UNTIL: :on_kw,
+      KEYWORD_UNTIL_MODIFIER: :on_kw,
+      KEYWORD_WHEN: :on_kw,
+      KEYWORD_WHILE: :on_kw,
+      KEYWORD_WHILE_MODIFIER: :on_kw,
+      KEYWORD_YIELD: :on_kw,
+      LABEL: :on_label,
+      LABEL_END: :on_label_end,
+      LAMBDA_BEGIN: :on_tlambeg,
+      LESS: :on_op,
+      LESS_EQUAL: :on_op,
+      LESS_EQUAL_GREATER: :on_op,
+      LESS_LESS: :on_op,
+      LESS_LESS_EQUAL: :on_op,
+      METHOD_NAME: :on_ident,
+      MINUS: :on_op,
+      MINUS_EQUAL: :on_op,
+      MINUS_GREATER: :on_tlambda,
+      NEWLINE: :on_nl,
+      NUMBERED_REFERENCE: :on_backref,
+      PARENTHESIS_LEFT: :on_lparen,
+      PARENTHESIS_LEFT_PARENTHESES: :on_lparen,
+      PARENTHESIS_RIGHT: :on_rparen,
+      PERCENT: :on_op,
+      PERCENT_EQUAL: :on_op,
+      PERCENT_LOWER_I: :on_qsymbols_beg,
+      PERCENT_LOWER_W: :on_qwords_beg,
+      PERCENT_LOWER_X: :on_backtick,
+      PERCENT_UPPER_I: :on_symbols_beg,
+      PERCENT_UPPER_W: :on_words_beg,
+      PIPE: :on_op,
+      PIPE_EQUAL: :on_op,
+      PIPE_PIPE: :on_op,
+      PIPE_PIPE_EQUAL: :on_op,
+      PLUS: :on_op,
+      PLUS_EQUAL: :on_op,
+      QUESTION_MARK: :on_op,
+      RATIONAL_FLOAT: :on_rational,
+      RATIONAL_INTEGER: :on_rational,
+      REGEXP_BEGIN: :on_regexp_beg,
+      REGEXP_END: :on_regexp_end,
+      SEMICOLON: :on_semicolon,
+      SLASH: :on_op,
+      SLASH_EQUAL: :on_op,
+      STAR: :on_op,
+      STAR_EQUAL: :on_op,
+      STAR_STAR: :on_op,
+      STAR_STAR_EQUAL: :on_op,
+      STRING_BEGIN: :on_tstring_beg,
+      STRING_CONTENT: :on_tstring_content,
+      STRING_END: :on_tstring_end,
+      SYMBOL_BEGIN: :on_symbeg,
+      TILDE: :on_op,
+      UAMPERSAND: :on_op,
+      UCOLON_COLON: :on_op,
+      UDOT_DOT: :on_op,
+      UDOT_DOT_DOT: :on_op,
+      UMINUS: :on_op,
+      UMINUS_NUM: :on_op,
+      UPLUS: :on_op,
+      USTAR: :on_op,
+      USTAR_STAR: :on_op,
+      WORDS_SEP: :on_words_sep,
+      "__END__": :on___end__
+    }.freeze
+
+    # A heredoc in this case is a list of tokens that belong to the body of the
+    # heredoc that should be appended onto the list of tokens when the heredoc
+    # closes.
+    module Heredoc # :nodoc:
+      # Heredocs that are no dash or tilde heredocs are just a list of tokens.
+      # We need to keep them around so that we can insert them in the correct
+      # order back into the token stream and set the state of the last token to
+      # the state that the heredoc was opened in.
+      class PlainHeredoc # :nodoc:
+        attr_reader :tokens #: Array[lex_compat_token]
+
+        #: () -> void
+        def initialize
+          @tokens = []
+        end
+
+        #: (lex_compat_token token) -> void
+        def <<(token)
+          tokens << token
+        end
+
+        #: () -> Array[lex_compat_token]
+        def to_a
+          tokens
+        end
+      end
+
+      # Dash heredocs are a little more complicated. They are a list of tokens
+      # that need to be split on "\\\n" to mimic Ripper's behavior. We also need
+      # to keep track of the state that the heredoc was opened in.
+      class DashHeredoc # :nodoc:
+        attr_reader :split #: bool
+        attr_reader :tokens #: Array[lex_compat_token]
+
+        #: (bool split) -> void
+        def initialize(split)
+          @split = split
+          @tokens = []
+        end
+
+        #: (lex_compat_token token) -> void
+        def <<(token)
+          tokens << token
+        end
+
+        #: () -> Array[lex_compat_token]
+        def to_a
+          embexpr_balance = 0
+
+          tokens.each_with_object([]) do |token, results| #$ Array[lex_compat_token]
+            case token[1]
+            when :on_embexpr_beg
+              embexpr_balance += 1
+              results << token
+            when :on_embexpr_end
+              embexpr_balance -= 1
+              results << token
+            when :on_tstring_content
+              if embexpr_balance == 0
+                lineno = token[0][0]
+                column = token[0][1]
+
+                if split
+                  # Split on "\\\n" to mimic Ripper's behavior. Use a lookbehind
+                  # to keep the delimiter in the result.
+                  token[2].split(/(?<=[^\\]\\\n)|(?<=[^\\]\\\r\n)/).each_with_index do |value, index|
+                    column = 0 if index > 0
+                    results << [[lineno, column], :on_tstring_content, value, token[3]]
+                    lineno += value.count("\n")
+                  end
+                else
+                  results << token
+                end
+              else
+                results << token
+              end
+            else
+              results << token
+            end
+          end
+        end
+      end
+
+      # Heredocs that are dedenting heredocs are a little more complicated.
+      # Ripper outputs on_ignored_sp tokens for the whitespace that is being
+      # removed from the output. prism only modifies the node itself and keeps
+      # the token the same. This simplifies prism, but makes comparing against
+      # Ripper much harder because there is a length mismatch.
+      #
+      # Fortunately, we already have to pull out the heredoc tokens in order to
+      # insert them into the stream in the correct order. As such, we can do
+      # some extra manipulation on the tokens to make them match Ripper's
+      # output by mirroring the dedent logic that Ripper uses.
+      class DedentingHeredoc # :nodoc:
+        TAB_WIDTH = 8
+
+        attr_reader :tokens #: Array[lex_compat_token]
+        attr_reader :dedent_next #: bool
+        attr_reader :dedent #: Integer?
+        attr_reader :embexpr_balance #: Integer
+        # @rbs @ended_on_newline: bool
+
+        #: () -> void
+        def initialize
+          @tokens = []
+          @dedent_next = true
+          @dedent = nil
+          @embexpr_balance = 0
+          @ended_on_newline = false
+        end
+
+        # As tokens are coming in, we track the minimum amount of common leading
+        # whitespace on plain string content tokens. This allows us to later
+        # remove that amount of whitespace from the beginning of each line.
+        #
+        #: (lex_compat_token token) -> void
+        def <<(token)
+          case token[1]
+          when :on_embexpr_beg, :on_heredoc_beg
+            @embexpr_balance += 1
+            @dedent = 0 if @dedent_next && @ended_on_newline
+          when :on_embexpr_end, :on_heredoc_end
+            @embexpr_balance -= 1
+          when :on_tstring_content
+            if embexpr_balance == 0
+              line = token[2]
+
+              if dedent_next && !(line.strip.empty? && line.end_with?("\n"))
+                leading = line[/\A(\s*)\n?/, 1] #: String
+                next_dedent = 0
+
+                leading.each_char do |char|
+                  if char == "\t"
+                    next_dedent = next_dedent - (next_dedent % TAB_WIDTH) + TAB_WIDTH
+                  else
+                    next_dedent += 1
+                  end
+                end
+
+                @dedent = [dedent, next_dedent].compact.min
+                @dedent_next = true
+                @ended_on_newline = line.end_with?("\n")
+                tokens << token
+                return
+              end
+            end
+          end
+
+          @dedent_next = token[1] == :on_tstring_content && embexpr_balance == 0
+          @ended_on_newline = false
+          tokens << token
+        end
+
+        #: () -> Array[lex_compat_token]
+        def to_a
+          # If every line in the heredoc is blank, we still need to split up the
+          # string content token into multiple tokens.
+          if dedent.nil?
+            results = [] #: Array[lex_compat_token]
+            embexpr_balance = 0
+
+            tokens.each do |token|
+              case token[1]
+              when :on_embexpr_beg, :on_heredoc_beg
+                embexpr_balance += 1
+                results << token
+              when :on_embexpr_end, :on_heredoc_end
+                embexpr_balance -= 1
+                results << token
+              when :on_tstring_content
+                if embexpr_balance == 0
+                  lineno = token[0][0]
+                  column = token[0][1]
+
+                  token[2].split(/(?<=\n)/).each_with_index do |value, index|
+                    column = 0 if index > 0
+                    results << [[lineno, column], :on_tstring_content, value, token[3]]
+                    lineno += 1
+                  end
+                else
+                  results << token
+                end
+              else
+                results << token
+              end
+            end
+
+            return results
+          end
+
+          # If the minimum common whitespace is 0, then we need to concatenate
+          # string nodes together that are immediately adjacent.
+          if dedent == 0
+            results = [] #: Array[lex_compat_token]
+            embexpr_balance = 0
+
+            index = 0
+            max_index = tokens.length
+
+            while index < max_index
+              token = tokens[index]
+              results << token
+              index += 1
+
+              case token[1]
+              when :on_embexpr_beg, :on_heredoc_beg
+                embexpr_balance += 1
+              when :on_embexpr_end, :on_heredoc_end
+                embexpr_balance -= 1
+              when :on_tstring_content
+                if embexpr_balance == 0
+                  while index < max_index && tokens[index][1] == :on_tstring_content && !token[2].match?(/\\\r?\n\z/)
+                    token[2] << tokens[index][2]
+                    index += 1
+                  end
+                end
+              end
+            end
+
+            return results
+          end
+
+          # Otherwise, we're going to run through each token in the list and
+          # insert on_ignored_sp tokens for the amount of dedent that we need to
+          # perform. We also need to remove the dedent from the beginning of
+          # each line of plain string content tokens.
+          results = [] #: Array[lex_compat_token]
+          dedent_next = true
+          embexpr_balance = 0
+
+          tokens.each do |token|
+            # Notice that the structure of this conditional largely matches the
+            # whitespace calculation we performed above. This is because
+            # checking if the subsequent token needs to be dedented is common to
+            # both the dedent calculation and the ignored_sp insertion.
+            case token[1]
+            when :on_embexpr_beg
+              embexpr_balance += 1
+              results << token
+            when :on_embexpr_end
+              embexpr_balance -= 1
+              results << token
+            when :on_tstring_content
+              if embexpr_balance == 0
+                # Here we're going to split the string on newlines, but maintain
+                # the newlines in the resulting array. We'll do that with a look
+                # behind assertion.
+                splits = token[2].split(/(?<=\n)/)
+                index = 0
+
+                while index < splits.length
+                  line = splits[index]
+                  lineno = token[0][0] + index
+                  column = token[0][1]
+
+                  # Blank lines do not count toward common leading whitespace
+                  # calculation and do not need to be dedented.
+                  if dedent_next || index > 0
+                    column = 0
+                  end
+
+                  # If the dedent is 0 and we're not supposed to dedent the next
+                  # line or this line doesn't start with whitespace, then we
+                  # should concatenate the rest of the string to match ripper.
+                  if dedent == 0 && (!dedent_next || !line.start_with?(/\s/))
+                    unjoined = splits[index..] #: Array[String]
+                    line = unjoined.join
+                    index = splits.length
+                  end
+
+                  # If we are supposed to dedent this line or if this is not the
+                  # first line of the string and this line isn't entirely blank,
+                  # then we need to insert an on_ignored_sp token and remove the
+                  # dedent from the beginning of the line.
+                  if (dedent > 0) && (dedent_next || index > 0)
+                    deleting = 0
+                    deleted_chars = [] #: Array[String]
+
+                    # Gather up all of the characters that we're going to
+                    # delete, stopping when you hit a character that would put
+                    # you over the dedent amount.
+                    line.each_char.with_index do |char, i|
+                      case char
+                      when "\r"
+                        if line[i + 1] == "\n"
+                          break
+                        end
+                      when "\n"
+                        break
+                      when "\t"
+                        deleting = deleting - (deleting % TAB_WIDTH) + TAB_WIDTH
+                      else
+                        deleting += 1
+                      end
+
+                      break if deleting > dedent
+                      deleted_chars << char
+                    end
+
+                    # If we have something to delete, then delete it from the
+                    # string and insert an on_ignored_sp token.
+                    if deleted_chars.any?
+                      ignored = deleted_chars.join
+                      line.delete_prefix!(ignored)
+
+                      results << [[lineno, 0], :on_ignored_sp, ignored, token[3]]
+                      column = ignored.length
+                    end
+                  end
+
+                  results << [[lineno, column], token[1], line, token[3]] unless line.empty?
+                  index += 1
+                end
+              else
+                results << token
+              end
+            else
+              results << token
+            end
+
+            dedent_next =
+              ((token[1] == :on_tstring_content) || (token[1] == :on_heredoc_end)) &&
+              embexpr_balance == 0
+          end
+
+          results
+        end
+      end
+
+      # Here we will split between the two types of heredocs and return the
+      # object that will store their tokens.
+      #--
+      #: (lex_compat_token opening) -> (PlainHeredoc | DashHeredoc | DedentingHeredoc)
+      def self.build(opening)
+        case opening[2][2]
+        when "~"
+          DedentingHeredoc.new
+        when "-"
+          DashHeredoc.new(opening[2][3] != "'")
+        else
+          PlainHeredoc.new
+        end
+      end
+    end
+
+    private_constant :Heredoc
+
+    # In previous versions of Ruby, Ripper wouldn't flush the bom before the
+    # first token, so we had to have a hack in place to account for that.
+    BOM_FLUSHED = RUBY_VERSION >= "3.3.0"
+    private_constant :BOM_FLUSHED
+
+    attr_reader :options #: Hash[Symbol, untyped]
+    # @rbs @source: String
+
+    #: (String source, **untyped options) -> void
+    def initialize(source, **options)
+      @source = source
+      @options = options
+    end
+
+    #: () -> Result
+    def result
+      tokens = [] #: Array[lex_compat_token]
+
+      state = :default
+      heredoc_stack = [[]] #: Array[Array[Heredoc::PlainHeredoc | Heredoc::DashHeredoc | Heredoc::DedentingHeredoc]]
+
+      result = Prism.lex(@source, **options)
+      source = result.source
+      result_value = result.value
+      previous_state = nil #: Translation::Ripper::Lexer::State?
+      last_heredoc_end = nil #: Integer?
+      eof_token = nil #: Token?
+
+      bom = source.slice(0, 3) == "\xEF\xBB\xBF"
+
+      result_value.each_with_index do |(prism_token, prism_state), index|
+        lineno = prism_token.location.start_line
+        column = prism_token.location.start_column
+
+        event = RIPPER.fetch(prism_token.type)
+        value = prism_token.value
+        lex_state = Translation::Ripper::Lexer::State[prism_state]
+
+        # If there's a UTF-8 byte-order mark as the start of the file, then for
+        # certain tokens ripper sets the first token back by 3 bytes. It also
+        # keeps the byte order mark in the first token's value. This is weird,
+        # and I don't want to mirror that in our parser. So instead, we'll match
+        # up the columns and values here.
+        if bom && lineno == 1
+          column -= 3
+
+          if index == 0 && column == 0 && !BOM_FLUSHED
+            flushed =
+              case prism_token.type
+              when :BACK_REFERENCE, :INSTANCE_VARIABLE, :CLASS_VARIABLE,
+                  :GLOBAL_VARIABLE, :NUMBERED_REFERENCE, :PERCENT_LOWER_I,
+                  :PERCENT_LOWER_X, :PERCENT_LOWER_W, :PERCENT_UPPER_I,
+                  :PERCENT_UPPER_W, :STRING_BEGIN
+                true
+              when :REGEXP_BEGIN, :SYMBOL_BEGIN
+                value.start_with?("%")
+              else
+                false
+              end
+
+            unless flushed
+              column -= 3
+              value.prepend(String.new("\xEF\xBB\xBF", encoding: value.encoding))
+            end
+          end
+        end
+
+        lex_compat_token =
+          case event
+          when :on___end__
+            # Ripper doesn't include the rest of the token in the event, so we need to
+            # trim it down to just the content on the first line.
+            value = value[0..value.index("\n")] #: String
+            [[lineno, column], event, value, lex_state]
+          when :on_comment
+            [[lineno, column], event, value, lex_state]
+          when :on_heredoc_end
+            # Heredoc end tokens can be emitted in an odd order, so we don't
+            # want to bother comparing the state on them.
+            last_heredoc_end = prism_token.location.end_offset
+            [[lineno, column], event, value, lex_state]
+          when :on_embexpr_end
+            [[lineno, column], event, value, lex_state]
+          when :on_words_sep
+            # Ripper emits one token each per line.
+            value.each_line.with_index do |line, index|
+              if index > 0
+                lineno += 1
+                column = 0
+              end
+              tokens << [[lineno, column], event, line, lex_state]
+            end
+            tokens.pop #: lex_compat_token
+          when :on_regexp_end
+            # On regex end, Ripper scans and then sets end state, so the ripper
+            # lexed output is begin, when it should be end. prism sets lex state
+            # correctly to end state, but we want to be able to compare against
+            # Ripper's lexed state. So here, if it's a regexp end token, we
+            # output the state as the previous state, solely for the sake of
+            # comparison.
+            previous_token = result_value[index - 1][0]
+            lex_state =
+              if RIPPER.fetch(previous_token.type) == :on_embexpr_end
+                # If the previous token is embexpr_end, then we have to do even
+                # more processing. The end of an embedded expression sets the
+                # state to the state that it had at the beginning of the
+                # embedded expression. So we have to go and find that state and
+                # set it here.
+                counter = 1
+                current_index = index - 1
+
+                until counter == 0
+                  current_index -= 1
+                  current_event = RIPPER.fetch(result_value[current_index][0].type)
+                  counter += { on_embexpr_beg: -1, on_embexpr_end: 1 }[current_event] || 0
+                end
+
+                Translation::Ripper::Lexer::State[result_value[current_index][1]]
+              else
+                previous_state
+              end
+
+            [[lineno, column], event, value, lex_state]
+          when :on_eof
+            eof_token = prism_token
+            previous_token = result_value[index - 1][0]
+
+            # If we're at the end of the file and the previous token was a
+            # comment and there is still whitespace after the comment, then
+            # Ripper will append a on_nl token (even though there isn't
+            # necessarily a newline). We mirror that here.
+            if previous_token.type == :COMMENT
+              # If the comment is at the start of a heredoc: <<HEREDOC # comment
+              # then the comment's end_offset is up near the heredoc_beg.
+              # This is not the correct offset to use for figuring out if
+              # there is trailing whitespace after the last token.
+              # Use the greater offset of the two to determine the start of
+              # the trailing whitespace.
+              start_offset = [previous_token.location.end_offset, last_heredoc_end].compact.max
+              end_offset = prism_token.location.start_offset
+
+              if start_offset < end_offset
+                if bom
+                  start_offset += 3
+                  end_offset += 3
+                end
+
+                tokens << [[lineno, 0], :on_nl, source.slice(start_offset, end_offset - start_offset), lex_state]
+              end
+            end
+
+            [[lineno, column], event, value, lex_state]
+          else
+            [[lineno, column], event, value, lex_state]
+          end #: lex_compat_token
+
+        previous_state = lex_state
+
+        # The order in which tokens appear in our lexer is different from the
+        # order that they appear in Ripper. When we hit the declaration of a
+        # heredoc in prism, we skip forward and lex the rest of the content of
+        # the heredoc before going back and lexing at the end of the heredoc
+        # identifier.
+        #
+        # To match up to ripper, we keep a small state variable around here to
+        # track whether we're in the middle of a heredoc or not. In this way we
+        # can shuffle around the token to match Ripper's output.
+        case state
+        when :default
+          # The default state is when there are no heredocs at all. In this
+          # state we can append the token to the list of tokens and move on.
+          tokens << lex_compat_token
+
+          # If we get the declaration of a heredoc, then we open a new heredoc
+          # and move into the heredoc_opened state.
+          if event == :on_heredoc_beg
+            state = :heredoc_opened
+            heredoc_stack.last << Heredoc.build(lex_compat_token)
+          end
+        when :heredoc_opened
+          # The heredoc_opened state is when we've seen the declaration of a
+          # heredoc and are now lexing the body of the heredoc. In this state we
+          # push tokens onto the most recently created heredoc.
+          heredoc_stack.last.last << lex_compat_token
+
+          case event
+          when :on_heredoc_beg
+            # If we receive a heredoc declaration while lexing the body of a
+            # heredoc, this means we have nested heredocs. In this case we'll
+            # push a new heredoc onto the stack and stay in the heredoc_opened
+            # state since we're now lexing the body of the new heredoc.
+            heredoc_stack << [Heredoc.build(lex_compat_token)]
+          when :on_heredoc_end
+            # If we receive the end of a heredoc, then we're done lexing the
+            # body of the heredoc. In this case we now have a completed heredoc
+            # but need to wait for the next newline to push it into the token
+            # stream.
+            state = :heredoc_closed
+          end
+        when :heredoc_closed
+          if %i[on_nl on_ignored_nl on_comment].include?(event) || ((event == :on_tstring_content) && value.end_with?("\n"))
+            if heredoc_stack.size > 1
+              flushing = heredoc_stack.pop #: Array[Heredoc::PlainHeredoc | Heredoc::DashHeredoc | Heredoc::DedentingHeredoc]
+              heredoc_stack.last.last << lex_compat_token
+
+              flushing.each do |heredoc|
+                heredoc.to_a.each do |flushed_token|
+                  heredoc_stack.last.last << flushed_token
+                end
+              end
+
+              state = :heredoc_opened
+              next
+            end
+          elsif event == :on_heredoc_beg
+            tokens << lex_compat_token
+            state = :heredoc_opened
+            heredoc_stack.last << Heredoc.build(lex_compat_token)
+            next
+          elsif heredoc_stack.size > 1
+            heredoc_stack[-2].last << lex_compat_token
+            next
+          end
+
+          heredoc_stack.last.each do |heredoc|
+            tokens.concat(heredoc.to_a)
+          end
+
+          heredoc_stack.last.clear
+          state = :default
+
+          tokens << lex_compat_token
+        end
+      end
+
+      # Drop the EOF token from the list. The EOF token may not be
+      # present if the source was syntax invalid
+      if tokens.dig(-1, 1) == :on_eof
+        tokens = tokens[0...-1] #: Array[lex_compat_token]
+      end
+
+      # We sort by location because Ripper.lex sorts.
+      tokens.sort_by! do |token|
+        line, column = token[0]
+        source.byte_offset(line, column)
+      end
+
+      tokens = post_process_tokens(tokens, source, result.data_loc, bom, eof_token)
+
+      Result.new(tokens, result.comments, result.magic_comments, result.data_loc, result.errors, result.warnings, result.continuable?, source)
+    end
+
+    private
+
+    #: (Array[lex_compat_token] tokens, Source source, Location? data_loc, bool bom, Token? eof_token) -> Array[lex_compat_token]
+    def post_process_tokens(tokens, source, data_loc, bom, eof_token)
+      new_tokens = [] #: Array[lex_compat_token]
+
+      prev_token_state = Translation::Ripper::Lexer::State[Translation::Ripper::EXPR_BEG]
+      prev_token_end = bom ? 3 : 0
+
+      cache = Translation::Ripper::LineAndColumnCache.new(source)
+
+      tokens.each do |token|
+        # Skip missing heredoc ends.
+        next if token[1] == :on_heredoc_end && token[2] == ""
+
+        # Add :on_sp tokens.
+        line, column = token[0]
+        start_offset = source.byte_offset(line, column)
+
+        # Ripper reports columns on line 1 without counting the BOM, so we
+        # adjust to get the real offset
+        start_offset += 3 if line == 1 && bom
+
+        if start_offset > prev_token_end
+          sp_value = source.slice(prev_token_end, start_offset - prev_token_end)
+          sp_line, sp_column = cache.line_and_column(prev_token_end)
+          # Ripper reports columns on line 1 without counting the BOM
+          sp_column -= 3 if sp_line == 1 && bom
+          continuation_index = sp_value.byteindex("\\")
+
+          # ripper emits up to three :on_sp tokens when line continuations are used
+          if continuation_index
+            next_whitespace_index = continuation_index + 1
+            next_whitespace_index += 1 if sp_value.byteslice(next_whitespace_index) == "\r"
+            next_whitespace_index += 1
+            first_whitespace = sp_value[0...continuation_index] #: String
+            continuation = sp_value[continuation_index...next_whitespace_index] #: String
+            second_whitespace = sp_value[next_whitespace_index..] || ""
+
+            new_tokens << [[sp_line, sp_column], :on_sp, first_whitespace, prev_token_state] unless first_whitespace.empty?
+            new_tokens << [[sp_line, sp_column + continuation_index], :on_sp, continuation, prev_token_state]
+            new_tokens << [[sp_line + 1, 0], :on_sp, second_whitespace, prev_token_state] unless second_whitespace.empty?
+          else
+            new_tokens << [[sp_line, sp_column], :on_sp, sp_value, prev_token_state]
+          end
+        end
+
+        new_tokens << token
+        prev_token_state = token[3]
+        prev_token_end = start_offset + token[2].bytesize
+      end
+
+      if !data_loc && eof_token # no trailing :on_sp with __END__ as it is always preceded by :on_nl
+        end_offset = eof_token.location.end_offset
+        if prev_token_end < end_offset
+          new_tokens << [
+            [source.line(prev_token_end), source.column(prev_token_end)],
+            :on_sp,
+            source.slice(prev_token_end, end_offset - prev_token_end),
+            prev_token_state
+          ]
+        end
+      end
+
+      new_tokens
+    end
+  end
+
+  private_constant :LexCompat
+end
diff --git a/lib/prism/node_ext.rb b/lib/prism/node_ext.rb
new file mode 100644
index 0000000000..8a6624e76d
--- /dev/null
+++ b/lib/prism/node_ext.rb
@@ -0,0 +1,388 @@
+# frozen_string_literal: true
+# :markup: markdown
+#--
+# rbs_inline: enabled
+
+#--
+# Here we are reopening the prism module to provide methods on nodes that aren't
+# templated and are meant as convenience methods.
+#++
+module Prism
+  class Node
+    #: (*String replacements) -> void
+    def deprecated(*replacements) # :nodoc:
+      location = caller_locations(1, 1)&.[](0)&.label
+      suggest = replacements.map { |replacement| "#{self.class}##{replacement}" }
+
+      warn(<<~MSG, uplevel: 1, category: :deprecated)
+        [deprecation]: #{self.class}##{location} is deprecated and will be \
+        removed in the next major version. Use #{suggest.join("/")} instead.
+        #{(caller(1, 3) || []).join("\n")}
+      MSG
+    end
+  end
+
+  module RegularExpressionOptions # :nodoc:
+    # Returns a numeric value that represents the flags that were used to create
+    # the regular expression.
+    #--
+    #: (Integer flags) -> Integer
+    def self.options(flags)
+      o = 0
+      o |= Regexp::IGNORECASE if flags.anybits?(RegularExpressionFlags::IGNORE_CASE)
+      o |= Regexp::EXTENDED if flags.anybits?(RegularExpressionFlags::EXTENDED)
+      o |= Regexp::MULTILINE if flags.anybits?(RegularExpressionFlags::MULTI_LINE)
+      o |= Regexp::FIXEDENCODING if flags.anybits?(RegularExpressionFlags::EUC_JP | RegularExpressionFlags::WINDOWS_31J | RegularExpressionFlags::UTF_8)
+      o |= Regexp::NOENCODING if flags.anybits?(RegularExpressionFlags::ASCII_8BIT)
+      o
+    end
+  end
+
+  class InterpolatedMatchLastLineNode < Node
+    # Returns a numeric value that represents the flags that were used to create
+    # the regular expression.
+    #--
+    #: () -> Integer
+    def options
+      RegularExpressionOptions.options(flags)
+    end
+  end
+
+  class InterpolatedRegularExpressionNode < Node
+    # Returns a numeric value that represents the flags that were used to create
+    # the regular expression.
+    #--
+    #: () -> Integer
+    def options
+      RegularExpressionOptions.options(flags)
+    end
+  end
+
+  class MatchLastLineNode < Node
+    # Returns a numeric value that represents the flags that were used to create
+    # the regular expression.
+    #--
+    #: () -> Integer
+    def options
+      RegularExpressionOptions.options(flags)
+    end
+  end
+
+  class RegularExpressionNode < Node
+    # Returns a numeric value that represents the flags that were used to create
+    # the regular expression.
+    #--
+    #: () -> Integer
+    def options
+      RegularExpressionOptions.options(flags)
+    end
+  end
+
+  private_constant :RegularExpressionOptions
+
+  module HeredocQuery # :nodoc:
+    # Returns true if this node was represented as a heredoc in the source code.
+    #--
+    #: (String? opening) -> bool?
+    def self.heredoc?(opening)
+      # @type self: InterpolatedStringNode | InterpolatedXStringNode | StringNode | XStringNode
+      opening&.start_with?("<<")
+    end
+  end
+
+  class InterpolatedStringNode < Node
+    # Returns true if this node was represented as a heredoc in the source code.
+    #--
+    #: () -> bool?
+    def heredoc?
+      HeredocQuery.heredoc?(opening)
+    end
+  end
+
+  class InterpolatedXStringNode < Node
+    # Returns true if this node was represented as a heredoc in the source code.
+    #--
+    #: () -> bool?
+    def heredoc?
+      HeredocQuery.heredoc?(opening)
+    end
+  end
+
+  class StringNode < Node
+    # Returns true if this node was represented as a heredoc in the source code.
+    #--
+    #: () -> bool?
+    def heredoc?
+      HeredocQuery.heredoc?(opening)
+    end
+
+    # Occasionally it's helpful to treat a string as if it were interpolated so
+    # that there's a consistent interface for working with strings.
+    #--
+    #: () -> InterpolatedStringNode
+    def to_interpolated
+      InterpolatedStringNode.new(
+        source,
+        -1,
+        location,
+        frozen? ? InterpolatedStringNodeFlags::FROZEN : 0,
+        opening_loc,
+        [copy(location: content_loc, opening_loc: nil, closing_loc: nil)],
+        closing_loc
+      )
+    end
+  end
+
+  class XStringNode < Node
+    # Returns true if this node was represented as a heredoc in the source code.
+    #--
+    #: () -> bool?
+    def heredoc?
+      HeredocQuery.heredoc?(opening)
+    end
+
+    # Occasionally it's helpful to treat a string as if it were interpolated so
+    # that there's a consistent interface for working with strings.
+    #--
+    #: () -> InterpolatedXStringNode
+    def to_interpolated
+      InterpolatedXStringNode.new(
+        source,
+        -1,
+        location,
+        flags,
+        opening_loc,
+        [StringNode.new(source, node_id, content_loc, 0, nil, content_loc, nil, unescaped)],
+        closing_loc
+      )
+    end
+  end
+
+  private_constant :HeredocQuery
+
+  class ImaginaryNode < Node
+    # Returns the value of the node as a Ruby Complex.
+    #--
+    #: () -> Complex
+    def value
+      Complex(0, numeric.value)
+    end
+  end
+
+  class RationalNode < Node
+    # Returns the value of the node as a Ruby Rational.
+    #--
+    #: () -> Rational
+    def value
+      Rational(numerator, denominator)
+    end
+  end
+
+  class ConstantReadNode < Node
+    # Returns the list of parts for the full name of this constant.
+    # For example: [:Foo]
+    #--
+    #: () -> Array[Symbol]
+    def full_name_parts
+      [name]
+    end
+
+    # Returns the full name of this constant. For example: "Foo"
+    #--
+    #: () -> String
+    def full_name
+      name.to_s
+    end
+  end
+
+  class ConstantWriteNode < Node
+    # Returns the list of parts for the full name of this constant.
+    # For example: [:Foo]
+    #--
+    #: () -> Array[Symbol]
+    def full_name_parts
+      [name]
+    end
+
+    # Returns the full name of this constant. For example: "Foo"
+    #--
+    #: () -> String
+    def full_name
+      name.to_s
+    end
+  end
+
+  class ConstantPathNode < Node
+    # An error class raised when dynamic parts are found while computing a
+    # constant path's full name. For example:
+    # Foo::Bar::Baz -> does not raise because all parts of the constant path are
+    # simple constants
+    # var::Bar::Baz -> raises because the first part of the constant path is a
+    # local variable
+    class DynamicPartsInConstantPathError < StandardError; end
+
+    # An error class raised when error recovery nodes are found while computing a
+    # constant path's full name. For example:
+    # Foo:: -> raises because the constant path is missing the last part
+    class ErrorRecoveryNodesInConstantPathError < StandardError; end
+
+    # Returns the list of parts for the full name of this constant path.
+    # For example: [:Foo, :Bar]
+    #--
+    #: () -> Array[Symbol]
+    def full_name_parts
+      parts = [] #: Array[Symbol]
+      current = self #: node?
+
+      while current.is_a?(ConstantPathNode)
+        name = current.name
+        if name.nil?
+          raise ErrorRecoveryNodesInConstantPathError, "Constant path contains error recovery nodes. Cannot compute full name"
+        end
+
+        parts.unshift(name)
+        current = current.parent
+      end
+
+      if !current.is_a?(ConstantReadNode) && !current.nil?
+        raise DynamicPartsInConstantPathError, "Constant path contains dynamic parts. Cannot compute full name"
+      end
+
+      parts.unshift(current&.name || :"")
+    end
+
+    # Returns the full name of this constant path. For example: "Foo::Bar"
+    #--
+    #: () -> String
+    def full_name
+      full_name_parts.join("::")
+    end
+  end
+
+  class ConstantPathTargetNode < Node
+    # Returns the list of parts for the full name of this constant path.
+    # For example: [:Foo, :Bar]
+    #--
+    #: () -> Array[Symbol]
+    def full_name_parts
+      parts =
+        case (parent = self.parent)
+        when ConstantPathNode, ConstantReadNode
+          parent.full_name_parts
+        when nil
+          [:""]
+        else
+          # e.g. self::Foo, (var)::Bar = baz
+          raise ConstantPathNode::DynamicPartsInConstantPathError, "Constant target path contains dynamic parts. Cannot compute full name"
+        end
+
+      if (name = self.name).nil?
+        raise ConstantPathNode::ErrorRecoveryNodesInConstantPathError, "Constant target path contains error recovery nodes. Cannot compute full name"
+      end
+
+      parts.push(name)
+    end
+
+    # Returns the full name of this constant path. For example: "Foo::Bar"
+    #--
+    #: () -> String
+    def full_name
+      full_name_parts.join("::")
+    end
+  end
+
+  class ConstantTargetNode < Node
+    # Returns the list of parts for the full name of this constant.
+    # For example: [:Foo]
+    #--
+    #: () -> Array[Symbol]
+    def full_name_parts
+      [name]
+    end
+
+    # Returns the full name of this constant. For example: "Foo"
+    #--
+    #: () -> String
+    def full_name
+      name.to_s
+    end
+  end
+
+  class ParametersNode < Node
+    # Mirrors the Method#parameters method.
+    #--
+    #: () -> Array[[Symbol, Symbol] | [Symbol]]
+    def signature
+      names = [] #: Array[[Symbol, Symbol] | [Symbol]]
+
+      requireds.each do |param|
+        names << (param.is_a?(MultiTargetNode) ? [:req] : [:req, param.name])
+      end
+
+      optionals.each { |param| names << [:opt, param.name] }
+
+      if (rest = self.rest).is_a?(RestParameterNode)
+        names << [:rest, rest.name || :*]
+      end
+
+      posts.each do |param|
+        case param
+        when MultiTargetNode
+          names << [:req]
+        when ErrorRecoveryNode
+          raise "Invalid syntax"
+        else
+          names << [:req, param.name]
+        end
+      end
+
+      # Regardless of the order in which the keywords were defined, the required
+      # keywords always come first followed by the optional keywords.
+      keyopt = [] #: Array[OptionalKeywordParameterNode]
+      keywords.each do |param|
+        if param.is_a?(OptionalKeywordParameterNode)
+          keyopt << param
+        else
+          names << [:keyreq, param.name]
+        end
+      end
+
+      keyopt.each { |param| names << [:key, param.name] }
+
+      case (keyword_rest = self.keyword_rest)
+      when ForwardingParameterNode
+        names.concat([[:rest, :*], [:keyrest, :**], [:block, :&]])
+      when KeywordRestParameterNode
+        names << [:keyrest, keyword_rest.name || :**]
+      when NoKeywordsParameterNode
+        names << [:nokey]
+      end
+
+      case (block = self.block)
+      when BlockParameterNode
+        names << [:block, block.name || :&]
+      when NoBlockParameterNode
+        names << [:noblock]
+      end
+
+      names
+    end
+  end
+
+  class CallNode < Node
+    # When a call node has the attribute_write flag set, it means that the call
+    # is using the attribute write syntax. This is either a method call to []=
+    # or a method call to a method that ends with =. Either way, the = sign is
+    # present in the source.
+    #
+    # Prism returns the message_loc _without_ the = sign attached, because there
+    # can be any amount of space between the message and the = sign. However,
+    # sometimes you want the location of the full message including the inner
+    # space and the = sign. This method provides that.
+    #--
+    #: () -> Location?
+    def full_message_loc
+      attribute_write? ? message_loc&.adjoin("=") : message_loc
+    end
+  end
+end
diff --git a/lib/prism/node_find.rb b/lib/prism/node_find.rb
new file mode 100644
index 0000000000..697ee430e8
--- /dev/null
+++ b/lib/prism/node_find.rb
@@ -0,0 +1,185 @@
+# frozen_string_literal: true
+# :markup: markdown
+#--
+# rbs_inline: enabled
+
+module Prism
+  # Finds the Prism AST node corresponding to a given Method, UnboundMethod,
+  # Proc, or Thread::Backtrace::Location. On CRuby, uses node_id from the
+  # instruction sequence for an exact match. On other implementations, falls
+  # back to best-effort matching by source location line number.
+  #
+  # This module is autoloaded so that programs that don't use Prism.find don't
+  # pay for its definition.
+  module NodeFind # :nodoc:
+    # Find the node for the given callable or backtrace location.
+    #--
+    #: (Method | UnboundMethod | Proc | Thread::Backtrace::Location callable, bool rubyvm) -> Node?
+    def self.find(callable, rubyvm)
+      case callable
+      when Proc
+        if rubyvm
+          RubyVMCallableFind.new.find(callable)
+        elsif callable.lambda?
+          LineLambdaFind.new.find(callable)
+        else
+          LineProcFind.new.find(callable)
+        end
+      when Method, UnboundMethod
+        if rubyvm
+          RubyVMCallableFind.new.find(callable)
+        else
+          LineMethodFind.new.find(callable)
+        end
+      when Thread::Backtrace::Location
+        if rubyvm
+          RubyVMBacktraceLocationFind.new.find(callable)
+        else
+          LineBacktraceLocationFind.new.find(callable)
+        end
+      else
+        raise ArgumentError, "Expected a Method, UnboundMethod, Proc, or Thread::Backtrace::Location, got #{callable.class}"
+      end
+    end
+
+    # Base class that handles parsing a file.
+    class Find
+      private
+
+      # Parse the given file path, returning a ParseResult or nil.
+      #--
+      #: (String? file) -> ParseResult?
+      def parse_file(file)
+        return unless file && File.readable?(file)
+        result = Prism.parse_file(file)
+        result if result.success?
+      end
+    end
+
+    # Finds the AST node for a Method, UnboundMethod, or Proc using the node_id
+    # from the instruction sequence.
+    class RubyVMCallableFind < Find
+      # Find the node for the given callable using the ISeq node_id.
+      #--
+      #: (Method | UnboundMethod | Proc callable) -> Node?
+      def find(callable)
+        return unless (source_location = callable.source_location)
+        return unless (result = parse_file(source_location[0]))
+        return unless (iseq = RubyVM::InstructionSequence.of(callable))
+
+        header = iseq.to_a[4]
+        return unless header[:parser] == :prism
+
+        result.value.find { |node| node.node_id == header[:node_id] }
+      end
+    end
+
+    # Finds the AST node for a Thread::Backtrace::Location using the node_id
+    # from the backtrace location.
+    class RubyVMBacktraceLocationFind < Find
+      # Find the node for the given backtrace location using node_id.
+      #--
+      #: (Thread::Backtrace::Location location) -> Node?
+      def find(location)
+        file = location.absolute_path || location.path
+        return unless (result = parse_file(file))
+        return unless RubyVM::AbstractSyntaxTree.respond_to?(:node_id_for_backtrace_location)
+
+        node_id = RubyVM::AbstractSyntaxTree.node_id_for_backtrace_location(location)
+
+        result.value.find { |node| node.node_id == node_id }
+      end
+    end
+
+    # Finds the AST node for a Method or UnboundMethod using best-effort line
+    # matching. Used on non-CRuby implementations.
+    class LineMethodFind < Find
+      # Find the node for the given method by matching on name and line.
+      #--
+      #: (Method | UnboundMethod callable) -> Node?
+      def find(callable)
+        return unless (source_location = callable.source_location)
+        return unless (result = parse_file(source_location[0]))
+
+        name = callable.name
+        start_line = source_location[1]
+
+        result.value.find do |node|
+          case node
+          when DefNode
+            node.name == name && node.location.start_line == start_line
+          when CallNode
+            node.block.is_a?(BlockNode) && node.location.start_line == start_line
+          else
+            false
+          end
+        end
+      end
+    end
+
+    # Finds the AST node for a lambda using best-effort line matching. Used
+    # on non-CRuby implementations.
+    class LineLambdaFind < Find
+      # Find the node for the given lambda by matching on line.
+      #--
+      #: (Proc callable) -> Node?
+      def find(callable)
+        return unless (source_location = callable.source_location)
+        return unless (result = parse_file(source_location[0]))
+
+        start_line = source_location[1]
+
+        result.value.find do |node|
+          case node
+          when LambdaNode
+            node.location.start_line == start_line
+          when CallNode
+            node.block.is_a?(BlockNode) && node.location.start_line == start_line
+          else
+            false
+          end
+        end
+      end
+    end
+
+    # Finds the AST node for a non-lambda Proc using best-effort line
+    # matching. Used on non-CRuby implementations.
+    class LineProcFind < Find
+      # Find the node for the given proc by matching on line.
+      #--
+      #: (Proc callable) -> Node?
+      def find(callable)
+        return unless (source_location = callable.source_location)
+        return unless (result = parse_file(source_location[0]))
+
+        start_line = source_location[1]
+
+        result.value.find do |node|
+          case node
+          when ForNode
+            node.location.start_line == start_line
+          when CallNode
+            node.block.is_a?(BlockNode) && node.location.start_line == start_line
+          else
+            false
+          end
+        end
+      end
+    end
+
+    # Finds the AST node for a Thread::Backtrace::Location using best-effort
+    # line matching. Used on non-CRuby implementations.
+    class LineBacktraceLocationFind < Find
+      # Find the node for the given backtrace location by matching on line.
+      #--
+      #: (Thread::Backtrace::Location location) -> Node?
+      def find(location)
+        file = location.absolute_path || location.path
+        return unless (result = parse_file(file))
+
+        start_line = location.lineno
+        result.value.find { |node| node.location.start_line == start_line }
+      end
+    end
+  end
+end
diff --git a/lib/prism/parse_result.rb b/lib/prism/parse_result.rb
new file mode 100644
index 0000000000..93d3c006b7
--- /dev/null
+++ b/lib/prism/parse_result.rb
@@ -0,0 +1,1211 @@
+# frozen_string_literal: true
+# :markup: markdown
+#--
+# rbs_inline: enabled
+
+module Prism
+  # @rbs!
+  #    # An internal interface for a cache that can be used to compute code
+  #    # units from byte offsets.
+  #    interface _CodeUnitsCache
+  #      def []: (Integer byte_offset) -> Integer
+  #    end
+
+  # This represents a source of Ruby code that has been parsed. It is used in
+  # conjunction with locations to allow them to resolve line numbers and source
+  # ranges.
+  class Source
+    # Create a new source object with the given source code. This method should
+    # be used instead of `new` and it will return either a `Source` or a
+    # specialized and more performant `ASCIISource` if no multibyte characters
+    # are present in the source code.
+    #
+    # Note that if you are calling this method manually, you will need to supply
+    # the start_line and offsets parameters. start_line is the line number that
+    # the source starts on, which is typically 1 but can be different if this
+    # source is a subset of a larger source or if this is an eval. offsets is an
+    # array of byte offsets for the start of each line in the source code, which
+    # can be calculated by iterating through the source code and recording the
+    # byte offset whenever a newline character is encountered.  The first
+    # element is always 0 to mark the first line.
+    #--
+    #: (String source, Integer start_line, Array[Integer] offsets) -> Source
+    def self.for(source, start_line, offsets)
+      if source.ascii_only?
+        ASCIISource.new(source, start_line, offsets)
+      elsif source.encoding == Encoding::BINARY
+        source.force_encoding(Encoding::UTF_8)
+
+        if source.valid_encoding?
+          new(source, start_line, offsets)
+        else
+          # This is an extremely niche use case where the file is marked as
+          # binary, contains multi-byte characters, and those characters are not
+          # valid UTF-8. In this case we'll mark it as binary and fall back to
+          # treating everything as a single-byte character. This _may_ cause
+          # problems when asking for code units, but it appears to be the
+          # cleanest solution at the moment.
+          source.force_encoding(Encoding::BINARY)
+          ASCIISource.new(source, start_line, offsets)
+        end
+      else
+        new(source, start_line, offsets)
+      end
+    end
+
+    # The source code that this source object represents.
+    attr_reader :source #: String
+
+    # The line number where this source starts.
+    attr_reader :start_line #: Integer
+
+    # The list of newline byte offsets in the source code. When initialized from
+    # the C extension, this may be a packed binary string of uint32_t values
+    # that is lazily unpacked on first access.
+    #--
+    #: () -> Array[Integer]
+    def offsets
+      offsets = @offsets
+      return offsets if offsets.is_a?(Array)
+      @offsets = offsets.unpack("L*")
+    end
+
+    # Create a new source object with the given source code. The offsets
+    # parameter can be either an Array of Integer byte offsets or a packed
+    # binary string of uint32_t values (from the C extension).
+    #--
+    #: (String source, Integer start_line, Array[Integer] | String offsets) -> void
+    def initialize(source, start_line, offsets)
+      @source = source
+      @start_line = start_line
+      @offsets = offsets
+    end
+
+    # Replace the value of start_line with the given value.
+    #--
+    #: (Integer start_line) -> void
+    def replace_start_line(start_line)
+      @start_line = start_line
+    end
+
+    # Replace the value of offsets with the given value.
+    #--
+    #: (Array[Integer] offsets) -> void
+    def replace_offsets(offsets)
+      @offsets = offsets
+    end
+
+    # Returns the encoding of the source code, which is set by parameters to the
+    # parser or by the encoding magic comment.
+    #--
+    #: () -> Encoding
+    def encoding
+      source.encoding
+    end
+
+    # Returns the lines of the source code as an array of strings.
+    #--
+    #: () -> Array[String]
+    def lines
+      source.lines
+    end
+
+    # Perform a byteslice on the source code using the given byte offset and
+    # byte length.
+    #--
+    #: (Integer byte_offset, Integer length) -> String
+    def slice(byte_offset, length)
+      source.byteslice(byte_offset, length) or raise
+    end
+
+    # Converts the line number and column in bytes to a byte offset.
+    #--
+    #: (Integer line, Integer column) -> Integer
+    def byte_offset(line, column)
+      normal = line - @start_line
+      raise IndexError if normal < 0
+      offsets.fetch(normal) + column
+    rescue IndexError
+      raise ArgumentError, "line #{line} is out of range"
+    end
+
+    # Binary search through the offsets to find the line number for the given
+    # byte offset.
+    #--
+    #: (Integer byte_offset) -> Integer
+    def line(byte_offset)
+      start_line + find_line(byte_offset)
+    end
+
+    # Return the byte offset of the start of the line corresponding to the given
+    # byte offset.
+    #--
+    #: (Integer byte_offset) -> Integer
+    def line_start(byte_offset)
+      offsets[find_line(byte_offset)]
+    end
+
+    # Returns the byte offset of the end of the line corresponding to the given
+    # byte offset.
+    #--
+    #: (Integer byte_offset) -> Integer
+    def line_end(byte_offset)
+      offsets[find_line(byte_offset) + 1] || source.bytesize
+    end
+
+    # Return the column in bytes for the given byte offset.
+    #--
+    #: (Integer byte_offset) -> Integer
+    def column(byte_offset)
+      byte_offset - line_start(byte_offset)
+    end
+
+    # Return the character offset for the given byte offset.
+    #--
+    #: (Integer byte_offset) -> Integer
+    def character_offset(byte_offset)
+      (source.byteslice(0, byte_offset) or raise).length
+    end
+
+    # Return the column in characters for the given byte offset.
+    #--
+    #: (Integer byte_offset) -> Integer
+    def character_column(byte_offset)
+      character_offset(byte_offset) - character_offset(line_start(byte_offset))
+    end
+
+    # Returns the offset from the start of the file for the given byte offset
+    # counting in code units for the given encoding.
+    #
+    # This method is tested with UTF-8, UTF-16, and UTF-32. If there is the
+    # concept of code units that differs from the number of characters in other
+    # encodings, it is not captured here.
+    #
+    # We purposefully replace invalid and undefined characters with replacement
+    # characters in this conversion. This happens for two reasons. First, it's
+    # possible that the given byte offset will not occur on a character
+    # boundary. Second, it's possible that the source code will contain a
+    # character that has no equivalent in the given encoding.
+    #--
+    #: (Integer byte_offset, Encoding encoding) -> Integer
+    def code_units_offset(byte_offset, encoding)
+      return byte_offset if encoding == Encoding::UTF_8
+
+      byteslice = (source.byteslice(0, byte_offset) or raise).encode(encoding, invalid: :replace, undef: :replace)
+
+      if encoding == Encoding::UTF_16LE || encoding == Encoding::UTF_16BE
+        byteslice.bytesize / 2
+      else
+        byteslice.length
+      end
+    end
+
+    # Generate a cache that targets a specific encoding for calculating code
+    # unit offsets.
+    #--
+    #: (Encoding encoding) -> CodeUnitsCache
+    def code_units_cache(encoding)
+      CodeUnitsCache.new(source, encoding)
+    end
+
+    # Returns the column in code units for the given encoding for the
+    # given byte offset.
+    #--
+    #: (Integer byte_offset, Encoding encoding) -> Integer
+    def code_units_column(byte_offset, encoding)
+      code_units_offset(byte_offset, encoding) - code_units_offset(line_start(byte_offset), encoding)
+    end
+
+    # Freeze this object and the objects it contains.
+    #--
+    #: () -> void
+    def deep_freeze
+      source.freeze
+      offsets.freeze
+      freeze
+    end
+
+    # Binary search through the offsets to find the index for the given
+    # byte offset.
+    #--
+    #: (Integer byte_offset) -> Integer
+    def find_line(byte_offset) # :nodoc:
+      index = offsets.bsearch_index { |offset| offset > byte_offset } || offsets.length
+      index - 1
+    end
+  end
+
+  # A cache that can be used to quickly compute code unit offsets from byte
+  # offsets. It purposefully provides only a single #[] method to access the
+  # cache in order to minimize surface area.
+  #
+  # Note that there are some known issues here that may or may not be addressed
+  # in the future:
+  #
+  # * The first is that there are issues when the cache computes values that are
+  #   not on character boundaries. This can result in subsequent computations
+  #   being off by one or more code units.
+  # * The second is that this cache is currently unbounded. In theory we could
+  #   introduce some kind of LRU cache to limit the number of entries, but this
+  #   has not yet been implemented.
+  #
+  class CodeUnitsCache
+    # Counter used for UTF-8, where one code unit equals one byte.
+    class UTF8Counter # :nodoc:
+      #: (Integer byte_offset, Integer byte_length) -> Integer
+      def count(byte_offset, byte_length)
+        byte_length
+      end
+    end
+
+    class UTF16Counter # :nodoc:
+      # @rbs @source: String
+      # @rbs @encoding: Encoding
+
+      #: (String source, Encoding encoding) -> void
+      def initialize(source, encoding)
+        @source = source
+        @encoding = encoding
+      end
+
+      #: (Integer byte_offset, Integer byte_length) -> Integer
+      def count(byte_offset, byte_length)
+        (@source.byteslice(byte_offset, byte_length) or raise).encode(@encoding, invalid: :replace, undef: :replace).bytesize / 2
+      end
+    end
+
+    # Counter used for UTF-32, where one code unit equals one code point and
+    # matches String#length. Also used as a best-effort fallback for any other
+    # encoding that does not have a dedicated counter.
+    class UTF32Counter # :nodoc:
+      # @rbs @source: String
+      # @rbs @encoding: Encoding
+
+      #: (String source, Encoding encoding) -> void
+      def initialize(source, encoding)
+        @source = source
+        @encoding = encoding
+      end
+
+      #: (Integer byte_offset, Integer byte_length) -> Integer
+      def count(byte_offset, byte_length)
+        (@source.byteslice(byte_offset, byte_length) or raise).encode(@encoding, invalid: :replace, undef: :replace).length
+      end
+    end
+
+    private_constant :UTF8Counter, :UTF16Counter, :UTF32Counter
+
+    # @rbs @source: String
+    # @rbs @counter: UTF8Counter | UTF16Counter | UTF32Counter
+    # @rbs @cache: Hash[Integer, Integer]
+    # @rbs @offsets: Array[Integer]
+
+    # Initialize a new cache with the given source and encoding.
+    #--
+    #: (String source, Encoding encoding) -> void
+    def initialize(source, encoding)
+      @source = source
+      @counter =
+        case encoding
+        when Encoding::UTF_8
+          UTF8Counter.new
+        when Encoding::UTF_16LE, Encoding::UTF_16BE
+          UTF16Counter.new(source, encoding)
+        else
+          UTF32Counter.new(source, encoding)
+        end
+
+      @cache = {} #: Hash[Integer, Integer]
+      @offsets = [] #: Array[Integer]
+    end
+
+    # Retrieve the code units offset from the given byte offset.
+    #--
+    #: (Integer byte_offset) -> Integer
+    def [](byte_offset)
+      @cache[byte_offset] ||=
+        if (index = @offsets.bsearch_index { |offset| offset > byte_offset }).nil?
+          @offsets << byte_offset
+          @counter.count(0, byte_offset)
+        elsif index == 0
+          @offsets.unshift(byte_offset)
+          @counter.count(0, byte_offset)
+        else
+          @offsets.insert(index, byte_offset)
+          offset = @offsets[index - 1]
+          @cache[offset] + @counter.count(offset, byte_offset - offset)
+        end
+    end
+  end
+
+  # Specialized version of Prism::Source for source code that includes ASCII
+  # characters only. This class is used to apply performance optimizations that
+  # cannot be applied to sources that include multibyte characters.
+  #
+  # In the extremely rare case that a source includes multi-byte characters but
+  # is marked as binary because of a magic encoding comment and it cannot be
+  # eagerly converted to UTF-8, this class will be used as well. This is because
+  # at that point we will treat everything as single-byte characters.
+  class ASCIISource < Source
+    # Return the character offset for the given byte offset.
+    #--
+    #: (Integer byte_offset) -> Integer
+    def character_offset(byte_offset)
+      byte_offset
+    end
+
+    # Return the column in characters for the given byte offset.
+    #--
+    #: (Integer byte_offset) -> Integer
+    def character_column(byte_offset)
+      byte_offset - line_start(byte_offset)
+    end
+
+    # Returns the offset from the start of the file for the given byte offset
+    # counting in code units for the given encoding.
+    #
+    # This method is tested with UTF-8, UTF-16, and UTF-32. If there is the
+    # concept of code units that differs from the number of characters in other
+    # encodings, it is not captured here.
+    #--
+    #: (Integer byte_offset, Encoding encoding) -> Integer
+    def code_units_offset(byte_offset, encoding)
+      byte_offset
+    end
+
+    # Returns a cache that is the identity function in order to maintain the
+    # same interface. We can do this because code units are always equivalent to
+    # byte offsets for ASCII-only sources.
+    #--
+    #: (Encoding encoding) -> _CodeUnitsCache
+    def code_units_cache(encoding)
+      ->(byte_offset) { byte_offset }
+    end
+
+    # Specialized version of `code_units_column` that does not depend on
+    # `code_units_offset`, which is a more expensive operation. This is
+    # essentially the same as `Prism::Source#column`.
+    #--
+    #: (Integer byte_offset, Encoding encoding) -> Integer
+    def code_units_column(byte_offset, encoding)
+      byte_offset - line_start(byte_offset)
+    end
+  end
+
+  # This represents a location in the source.
+  class Location
+    # A Source object that is used to determine more information from the given
+    # offset and length.
+    attr_reader :source #: Source
+    protected :source
+
+    # The byte offset from the beginning of the source where this location
+    # starts.
+    attr_reader :start_offset #: Integer
+
+    # The length of this location in bytes.
+    attr_reader :length #: Integer
+
+    # @rbs @leading_comments: Array[Comment]?
+    # @rbs @trailing_comments: Array[Comment]?
+
+    # Create a new location object with the given source, start byte offset, and
+    # byte length.
+    #--
+    #: (Source source, Integer start_offset, Integer length) -> void
+    def initialize(source, start_offset, length)
+      @source = source
+      @start_offset = start_offset
+      @length = length
+
+      # These are used to store comments that are associated with this location.
+      # They are initialized to `nil` to save on memory when there are no
+      # comments to be attached and/or the comment-related APIs are not used.
+      @leading_comments = nil
+      @trailing_comments = nil
+    end
+
+    # These are the comments that are associated with this location that exist
+    # before the start of this location.
+    #--
+    #: () -> Array[Comment]
+    def leading_comments
+      @leading_comments ||= []
+    end
+
+    # Attach a comment to the leading comments of this location.
+    #--
+    #: (Comment comment) -> void
+    def leading_comment(comment)
+      leading_comments << comment
+    end
+
+    # These are the comments that are associated with this location that exist
+    # after the end of this location.
+    #--
+    #: () -> Array[Comment]
+    def trailing_comments
+      @trailing_comments ||= []
+    end
+
+    # Attach a comment to the trailing comments of this location.
+    #--
+    #: (Comment comment) -> void
+    def trailing_comment(comment)
+      trailing_comments << comment
+    end
+
+    # Returns all comments that are associated with this location (both leading
+    # and trailing comments).
+    #--
+    #: () -> Array[Comment]
+    def comments
+      [*@leading_comments, *@trailing_comments] #: Array[Comment]
+    end
+
+    # Create a new location object with the given options.
+    #--
+    #: (?source: Source, ?start_offset: Integer, ?length: Integer) -> Location
+    def copy(source: self.source, start_offset: self.start_offset, length: self.length)
+      Location.new(source, start_offset, length)
+    end
+
+    # Returns a new location that is the result of chopping off the last byte.
+    #--
+    #: () -> Location
+    def chop
+      copy(length: length == 0 ? length : length - 1)
+    end
+
+    # Returns a string representation of this location.
+    #--
+    #: () -> String
+    def inspect # :nodoc:
+      "#<Prism::Location @start_offset=#{@start_offset} @length=#{@length} start_line=#{start_line}>"
+    end
+
+    # Returns all of the lines of the source code associated with this location.
+    #--
+    #: () -> Array[String]
+    def source_lines
+      source.lines
+    end
+
+    # The source code that this location represents.
+    #--
+    #: () -> String
+    def slice
+      source.slice(start_offset, length)
+    end
+
+    # The source code that this location represents starting from the beginning
+    # of the line that this location starts on to the end of the line that this
+    # location ends on.
+    #--
+    #: () -> String
+    def slice_lines
+      line_start = source.line_start(start_offset)
+      line_end = source.line_end(end_offset)
+      source.slice(line_start, line_end - line_start)
+    end
+
+    # The character offset from the beginning of the source where this location
+    # starts.
+    #--
+    #: () -> Integer
+    def start_character_offset
+      source.character_offset(start_offset)
+    end
+
+    # The offset from the start of the file in code units of the given encoding.
+    #--
+    #: (Encoding encoding) -> Integer
+    def start_code_units_offset(encoding = Encoding::UTF_16LE)
+      source.code_units_offset(start_offset, encoding)
+    end
+
+    # The start offset from the start of the file in code units using the given
+    # cache to fetch or calculate the value.
+    #--
+    #: (_CodeUnitsCache cache) -> Integer
+    def cached_start_code_units_offset(cache)
+      cache[start_offset]
+    end
+
+    # The byte offset from the beginning of the source where this location ends.
+    #--
+    #: () -> Integer
+    def end_offset
+      start_offset + length
+    end
+
+    # The character offset from the beginning of the source where this location
+    # ends.
+    #--
+    #: () -> Integer
+    def end_character_offset
+      source.character_offset(end_offset)
+    end
+
+    # The offset from the start of the file in code units of the given encoding.
+    #--
+    #: (Encoding encoding) -> Integer
+    def end_code_units_offset(encoding = Encoding::UTF_16LE)
+      source.code_units_offset(end_offset, encoding)
+    end
+
+    # The end offset from the start of the file in code units using the given
+    # cache to fetch or calculate the value.
+    #--
+    #: (_CodeUnitsCache cache) -> Integer
+    def cached_end_code_units_offset(cache)
+      cache[end_offset]
+    end
+
+    # The line number where this location starts.
+    #--
+    #: () -> Integer
+    def start_line
+      source.line(start_offset)
+    end
+
+    # The content of the line where this location starts before this location.
+    #--
+    #: () -> String
+    def start_line_slice
+      offset = source.line_start(start_offset)
+      source.slice(offset, start_offset - offset)
+    end
+
+    # The line number where this location ends.
+    #--
+    #: () -> Integer
+    def end_line
+      source.line(end_offset)
+    end
+
+    # The column in bytes where this location starts from the start of
+    # the line.
+    #--
+    #: () -> Integer
+    def start_column
+      source.column(start_offset)
+    end
+
+    # The column in characters where this location ends from the start of
+    # the line.
+    #--
+    #: () -> Integer
+    def start_character_column
+      source.character_column(start_offset)
+    end
+
+    # The column in code units of the given encoding where this location
+    # starts from the start of the line.
+    #--
+    #: (?Encoding encoding) -> Integer
+    def start_code_units_column(encoding = Encoding::UTF_16LE)
+      source.code_units_column(start_offset, encoding)
+    end
+
+    # The start column in code units using the given cache to fetch or calculate
+    # the value.
+    #--
+    #: (_CodeUnitsCache cache) -> Integer
+    def cached_start_code_units_column(cache)
+      cache[start_offset] - cache[source.line_start(start_offset)]
+    end
+
+    # The column in bytes where this location ends from the start of the
+    # line.
+    #--
+    #: () -> Integer
+    def end_column
+      source.column(end_offset)
+    end
+
+    # The column in characters where this location ends from the start of
+    # the line.
+    #--
+    #: () -> Integer
+    def end_character_column
+      source.character_column(end_offset)
+    end
+
+    # The column in code units of the given encoding where this location
+    # ends from the start of the line.
+    #--
+    #: (?Encoding encoding) -> Integer
+    def end_code_units_column(encoding = Encoding::UTF_16LE)
+      source.code_units_column(end_offset, encoding)
+    end
+
+    # The end column in code units using the given cache to fetch or calculate
+    # the value.
+    #--
+    #: (_CodeUnitsCache cache) -> Integer
+    def cached_end_code_units_column(cache)
+      cache[end_offset] - cache[source.line_start(end_offset)]
+    end
+
+    # Implement the hash pattern matching interface for Location.
+    #--
+    #: (Array[Symbol]? keys) -> Hash[Symbol, untyped]
+    def deconstruct_keys(keys) # :nodoc:
+      { start_offset: start_offset, end_offset: end_offset }
+    end
+
+    # Implement the pretty print interface for Location.
+    #--
+    #: (PP q) -> void
+    def pretty_print(q) # :nodoc:
+      q.text("(#{start_line},#{start_column})-(#{end_line},#{end_column})")
+    end
+
+    # Returns true if the given other location is equal to this location.
+    #--
+    #: (untyped other) -> bool
+    def ==(other)
+      Location === other &&
+        other.start_offset == start_offset &&
+        other.end_offset == end_offset
+    end
+
+    # Returns a new location that stretches from this location to the given
+    # other location. Raises an error if this location is not before the other
+    # location or if they don't share the same source.
+    #--
+    #: (Location other) -> Location
+    def join(other)
+      raise "Incompatible sources" if source != other.source
+      raise "Incompatible locations" if start_offset > other.start_offset
+
+      Location.new(source, start_offset, other.end_offset - start_offset)
+    end
+
+    # Join this location with the first occurrence of the string in the source
+    # that occurs after this location on the same line, and return the new
+    # location. This will raise an error if the string does not exist.
+    #--
+    #: (String string) -> Location
+    def adjoin(string)
+      line_suffix = source.slice(end_offset, source.line_end(end_offset) - end_offset)
+
+      line_suffix_index = line_suffix.byteindex(string)
+      raise "Could not find #{string}" if line_suffix_index.nil?
+
+      Location.new(source, start_offset, length + line_suffix_index + string.bytesize)
+    end
+  end
+
+  # This represents a comment that was encountered during parsing. It is the
+  # base class for all comment types.
+  class Comment
+    # The Location of this comment in the source.
+    attr_reader :location #: Location
+
+    # Create a new comment object with the given location.
+    #--
+    #: (Location location) -> void
+    def initialize(location)
+      @location = location
+    end
+
+    # Implement the hash pattern matching interface for Comment.
+    #--
+    #: (Array[Symbol]? keys) -> Hash[Symbol, untyped]
+    def deconstruct_keys(keys) # :nodoc:
+      { location: location }
+    end
+
+    # Returns the content of the comment by slicing it from the source code.
+    #--
+    #: () -> String
+    def slice
+      location.slice
+    end
+
+    # Returns true if this comment happens on the same line as other code and
+    # false if the comment is by itself. This can only be true for inline
+    # comments and should be false for block comments.
+    #--
+    #: () -> bool
+    def trailing?
+      raise NotImplementedError, "trailing? is not implemented for #{self.class}"
+    end
+  end
+
+  # InlineComment objects are the most common. They correspond to comments in
+  # the source file like this one that start with #.
+  class InlineComment < Comment
+    # Returns true if this comment happens on the same line as other code and
+    # false if the comment is by itself.
+    #--
+    #: () -> bool
+    def trailing?
+      !location.start_line_slice.strip.empty?
+    end
+
+    # Returns a string representation of this comment.
+    #--
+    #: () -> String
+    def inspect # :nodoc:
+      "#<Prism::InlineComment @location=#{location.inspect}>"
+    end
+  end
+
+  # EmbDocComment objects correspond to comments that are surrounded by =begin
+  # and =end.
+  class EmbDocComment < Comment
+    # Returns false. This can only be true for inline comments.
+    #--
+    #: () -> bool
+    def trailing?
+      false
+    end
+
+    # Returns a string representation of this comment.
+    #--
+    #: () -> String
+    def inspect # :nodoc:
+      "#<Prism::EmbDocComment @location=#{location.inspect}>"
+    end
+  end
+
+  # This represents a magic comment that was encountered during parsing.
+  class MagicComment
+    # A Location object representing the location of the key in the source.
+    attr_reader :key_loc #: Location
+
+    # A Location object representing the location of the value in the source.
+    attr_reader :value_loc #: Location
+
+    # Create a new magic comment object with the given key and value locations.
+    #--
+    #: (Location key_loc, Location value_loc) -> void
+    def initialize(key_loc, value_loc)
+      @key_loc = key_loc
+      @value_loc = value_loc
+    end
+
+    # Returns the key of the magic comment by slicing it from the source code.
+    #--
+    #: () -> String
+    def key
+      key_loc.slice
+    end
+
+    # Returns the value of the magic comment by slicing it from the source code.
+    #--
+    #: () -> String
+    def value
+      value_loc.slice
+    end
+
+    # Implement the hash pattern matching interface for MagicComment.
+    #--
+    #: (Array[Symbol]? keys) -> Hash[Symbol, untyped]
+    def deconstruct_keys(keys) # :nodoc:
+      { key_loc: key_loc, value_loc: value_loc }
+    end
+
+    # Returns a string representation of this magic comment.
+    #--
+    #: () -> String
+    def inspect # :nodoc:
+      "#<Prism::MagicComment @key=#{key.inspect} @value=#{value.inspect}>"
+    end
+  end
+
+  # This represents an error that was encountered during parsing.
+  class ParseError
+    # The type of error. This is an _internal_ symbol that is used for
+    # communicating with translation layers. It is not meant to be public API.
+    attr_reader :type #: Symbol
+
+    # The message associated with this error.
+    attr_reader :message #: String
+
+    # A Location object representing the location of this error in the source.
+    attr_reader :location #: Location
+
+    # The level of this error.
+    attr_reader :level #: Symbol
+
+    # Create a new error object with the given message and location.
+    #--
+    #: (Symbol type, String message, Location location, Symbol level) -> void
+    def initialize(type, message, location, level)
+      @type = type
+      @message = message
+      @location = location
+      @level = level
+    end
+
+    # Implement the hash pattern matching interface for ParseError.
+    #--
+    #: (Array[Symbol]? keys) -> Hash[Symbol, untyped]
+    def deconstruct_keys(keys) # :nodoc:
+      { type: type, message: message, location: location, level: level }
+    end
+
+    # Returns a string representation of this error.
+    #--
+    #: () -> String
+    def inspect # :nodoc:
+      "#<Prism::ParseError @type=#{@type.inspect} @message=#{@message.inspect} @location=#{@location.inspect} @level=#{@level.inspect}>"
+    end
+  end
+
+  # This represents a warning that was encountered during parsing.
+  class ParseWarning
+    # The type of warning. This is an _internal_ symbol that is used for
+    # communicating with translation layers. It is not meant to be public API.
+    attr_reader :type #: Symbol
+
+    # The message associated with this warning.
+    attr_reader :message #: String
+
+    # A Location object representing the location of this warning in the source.
+    attr_reader :location #: Location
+
+    # The level of this warning.
+    attr_reader :level #: Symbol
+
+    # Create a new warning object with the given message and location.
+    #--
+    #: (Symbol type, String message, Location location, Symbol level) -> void
+    def initialize(type, message, location, level)
+      @type = type
+      @message = message
+      @location = location
+      @level = level
+    end
+
+    # Implement the hash pattern matching interface for ParseWarning.
+    #--
+    #: (Array[Symbol]? keys) -> Hash[Symbol, untyped]
+    def deconstruct_keys(keys) # :nodoc:
+      { type: type, message: message, location: location, level: level }
+    end
+
+    # Returns a string representation of this warning.
+    #--
+    #: () -> String
+    def inspect # :nodoc:
+      "#<Prism::ParseWarning @type=#{@type.inspect} @message=#{@message.inspect} @location=#{@location.inspect} @level=#{@level.inspect}>"
+    end
+  end
+
+  # This represents the result of a call to Prism.parse or Prism.parse_file.
+  # It contains the requested structure, any comments that were encounters,
+  # and any errors that were encountered.
+  class Result
+    # The list of comments that were encountered during parsing.
+    attr_reader :comments #: Array[Comment]
+
+    # The list of magic comments that were encountered during parsing.
+    attr_reader :magic_comments #: Array[MagicComment]
+
+    # An optional location that represents the location of the __END__ marker
+    # and the rest of the content of the file. This content is loaded into the
+    # DATA constant when the file being parsed is the main file being executed.
+    attr_reader :data_loc #: Location?
+
+    # The list of errors that were generated during parsing.
+    attr_reader :errors #: Array[ParseError]
+
+    # The list of warnings that were generated during parsing.
+    attr_reader :warnings #: Array[ParseWarning]
+
+    # A Source instance that represents the source code that was parsed.
+    attr_reader :source #: Source
+
+    # Create a new result object with the given values.
+    #--
+    #: (Array[Comment] comments, Array[MagicComment] magic_comments, Location? data_loc, Array[ParseError] errors, Array[ParseWarning] warnings, bool continuable, Source source) -> void
+    def initialize(comments, magic_comments, data_loc, errors, warnings, continuable, source)
+      @comments = comments
+      @magic_comments = magic_comments
+      @data_loc = data_loc
+      @errors = errors
+      @warnings = warnings
+      @continuable = continuable
+      @source = source
+    end
+
+    # Implement the hash pattern matching interface for Result.
+    #--
+    #: (Array[Symbol]? keys) -> Hash[Symbol, untyped]
+    def deconstruct_keys(keys) # :nodoc:
+      { comments: comments, magic_comments: magic_comments, data_loc: data_loc, errors: errors, warnings: warnings }
+    end
+
+    # Returns the encoding of the source code that was parsed.
+    #--
+    #: () -> Encoding
+    def encoding
+      source.encoding
+    end
+
+    # Returns true if there were no errors during parsing and false if there
+    # were.
+    #--
+    #: () -> bool
+    def success?
+      errors.empty?
+    end
+
+    # Returns true if there were errors during parsing and false if there were
+    # not.
+    #--
+    #: () -> bool
+    def failure?
+      !success?
+    end
+
+    # Returns true if the parsed source is an incomplete expression that could
+    # become valid with additional input. This is useful for REPL contexts (such
+    # as IRB) where the user may be entering a multi-line expression one line at
+    # a time and the implementation needs to determine whether to wait for more
+    # input or to evaluate what has been entered so far.
+    #
+    # Concretely, this returns true when every error present is caused by the
+    # parser reaching the end of the input before a construct was closed (e.g.
+    # an unclosed string, array, block, or keyword), and returns false when any
+    # error is caused by a token that makes the input structurally invalid
+    # regardless of what might follow (e.g. a stray `end`, `]`, or `)` with no
+    # matching opener).
+    #
+    # Examples:
+    #
+    #     Prism.parse("1 + [").continuable?      #=> true  (unclosed array)
+    #     Prism.parse("1 + ]").continuable?      #=> false (stray ])
+    #     Prism.parse("tap do").continuable?     #=> true  (unclosed block)
+    #     Prism.parse("end.tap do").continuable? #=> false (stray end)
+    #
+    #--
+    #: () -> bool
+    def continuable?
+      @continuable
+    end
+
+    # Create a code units cache for the given encoding.
+    #--
+    #: (Encoding encoding) -> _CodeUnitsCache
+    def code_units_cache(encoding)
+      source.code_units_cache(encoding)
+    end
+  end
+
+  # This is a result specific to the `parse` and `parse_file` methods.
+  class ParseResult < Result
+    autoload :Comments, "prism/parse_result/comments"
+    autoload :Errors, "prism/parse_result/errors"
+    autoload :Newlines, "prism/parse_result/newlines"
+
+    private_constant :Comments
+    private_constant :Errors
+    private_constant :Newlines
+
+    # The syntax tree that was parsed from the source code.
+    attr_reader :value #: ProgramNode
+
+    # Create a new parse result object with the given values.
+    #--
+    #: (ProgramNode value, Array[Comment] comments, Array[MagicComment] magic_comments, Location? data_loc, Array[ParseError] errors, Array[ParseWarning] warnings, bool continuable, Source source) -> void
+    def initialize(value, comments, magic_comments, data_loc, errors, warnings, continuable, source)
+      @value = value
+      super(comments, magic_comments, data_loc, errors, warnings, continuable, source)
+    end
+
+    # Implement the hash pattern matching interface for ParseResult.
+    #--
+    #: (Array[Symbol]? keys) -> Hash[Symbol, untyped]
+    def deconstruct_keys(keys) # :nodoc:
+      super.merge!(value: value)
+    end
+
+    # Attach the list of comments to their respective locations in the tree.
+    #--
+    #: () -> void
+    def attach_comments!
+      Comments.new(self).attach! # steep:ignore
+    end
+
+    # Walk the tree and mark nodes that are on a new line, loosely emulating
+    # the behavior of CRuby's `:line` tracepoint event.
+    #--
+    #: () -> void
+    def mark_newlines!
+      value.accept(Newlines.new(source.offsets.size)) # steep:ignore
+    end
+
+    # Returns a string representation of the syntax tree with the errors
+    # displayed inline.
+    #--
+    #: () -> String
+    def errors_format
+      Errors.new(self).format
+    end
+  end
+
+  # This is a result specific to the `lex` and `lex_file` methods.
+  class LexResult < Result
+    # The list of tokens that were parsed from the source code.
+    attr_reader :value #: Array[[Token, Integer]]
+
+    # Create a new lex result object with the given values.
+    #--
+    #: (Array[[Token, Integer]] value, Array[Comment] comments, Array[MagicComment] magic_comments, Location? data_loc, Array[ParseError] errors, Array[ParseWarning] warnings, bool continuable, Source source) -> void
+    def initialize(value, comments, magic_comments, data_loc, errors, warnings, continuable, source)
+      @value = value
+      super(comments, magic_comments, data_loc, errors, warnings, continuable, source)
+    end
+
+    # Implement the hash pattern matching interface for LexResult.
+    #--
+    #: (Array[Symbol]? keys) -> Hash[Symbol, untyped]
+    def deconstruct_keys(keys) # :nodoc:
+      super.merge!(value: value)
+    end
+  end
+
+  # This is a result specific to the `parse_lex` and `parse_lex_file` methods.
+  class ParseLexResult < Result
+    # A tuple of the syntax tree and the list of tokens that were parsed from
+    # the source code.
+    attr_reader :value #: [ProgramNode, Array[[Token, Integer]]]
+
+    # Create a new parse lex result object with the given values.
+    #--
+    #: ([ProgramNode, Array[[Token, Integer]]] value, Array[Comment] comments, Array[MagicComment] magic_comments, Location? data_loc, Array[ParseError] errors, Array[ParseWarning] warnings, bool continuable, Source source) -> void
+    def initialize(value, comments, magic_comments, data_loc, errors, warnings, continuable, source)
+      @value = value
+      super(comments, magic_comments, data_loc, errors, warnings, continuable, source)
+    end
+
+    # Implement the hash pattern matching interface for ParseLexResult.
+    #--
+    #: (Array[Symbol]? keys) -> Hash[Symbol, untyped]
+    def deconstruct_keys(keys) # :nodoc:
+      super.merge!(value: value)
+    end
+  end
+
+  # This represents a token from the Ruby source.
+  class Token
+    # The Source object that represents the source this token came from.
+    attr_reader :source #: Source
+    private :source
+
+    # The type of token that this token is.
+    attr_reader :type #: Symbol
+
+    # A byteslice of the source that this token represents.
+    attr_reader :value #: String
+
+    # @rbs @location: Location | Integer
+
+    # Create a new token object with the given type, value, and location.
+    #--
+    #: (Source source, Symbol type, String value, Location | Integer location) -> void
+    def initialize(source, type, value, location)
+      @source = source
+      @type = type
+      @value = value
+      @location = location
+    end
+
+    # Implement the hash pattern matching interface for Token.
+    #--
+    #: (Array[Symbol]? keys) -> Hash[Symbol, untyped]
+    def deconstruct_keys(keys) # :nodoc:
+      { type: type, value: value, location: location }
+    end
+
+    # A Location object representing the location of this token in the source.
+    #--
+    #: () -> Location
+    def location
+      location = @location
+      return location if location.is_a?(Location)
+      @location = Location.new(source, location >> 32, location & 0xFFFFFFFF)
+    end
+
+    # Implement the pretty print interface for Token.
+    #--
+    #: (PP q) -> void
+    def pretty_print(q) # :nodoc:
+      q.group do
+        q.text(type.to_s)
+        self.location.pretty_print(q)
+        q.text("(")
+        q.nest(2) do
+          q.breakable("")
+          q.pp(value)
+        end
+        q.breakable("")
+        q.text(")")
+      end
+    end
+
+    # Returns true if the given other token is equal to this token.
+    #--
+    #: (untyped other) -> bool
+    def ==(other)
+      Token === other &&
+        other.type == type &&
+        other.value == value
+    end
+
+    # Returns a string representation of this token.
+    #--
+    #: () -> String
+    def inspect # :nodoc:
+      location
+      super
+    end
+
+    # Freeze this object and the objects it contains.
+    #--
+    #: () -> void
+    def deep_freeze
+      value.freeze
+      location.freeze
+      freeze
+    end
+  end
+
+  # This object is passed to the various Prism.* methods that accept the
+  # `scopes` option as an element of the list. It defines both the local
+  # variables visible at that scope as well as the forwarding parameters
+  # available at that scope.
+  class Scope
+    # The list of local variables that are defined in this scope. This should be
+    # defined as an array of symbols.
+    attr_reader :locals #: Array[Symbol]
+
+    # The list of local variables that are forwarded to the next scope. This
+    # should by defined as an array of symbols containing the specific values of
+    # :*, :**, :&, or :"...".
+    attr_reader :forwarding #: Array[Symbol]
+
+    # Create a new scope object with the given locals and forwarding.
+    #--
+    #: (Array[Symbol] locals, Array[Symbol] forwarding) -> void
+    def initialize(locals, forwarding)
+      @locals = locals
+      @forwarding = forwarding
+    end
+  end
+
+  # Create a new scope with the given locals and forwarding options that is
+  # suitable for passing into one of the Prism.* methods that accepts the
+  # `scopes` option.
+  #--
+  #: (?locals: Array[Symbol], ?forwarding: Array[Symbol]) -> Scope
+  def self.scope(locals: [], forwarding: [])
+    Scope.new(locals, forwarding)
+  end
+end
diff --git a/lib/prism/parse_result/comments.rb b/lib/prism/parse_result/comments.rb
new file mode 100644
index 0000000000..df80792d39
--- /dev/null
+++ b/lib/prism/parse_result/comments.rb
@@ -0,0 +1,219 @@
+# frozen_string_literal: true
+# :markup: markdown
+#--
+# rbs_inline: enabled
+
+module Prism
+  class ParseResult < Result
+    # When we've parsed the source, we have both the syntax tree and the list of
+    # comments that we found in the source. This class is responsible for
+    # walking the tree and finding the nearest location to attach each comment.
+    #
+    # It does this by first finding the nearest locations to each comment.
+    # Locations can either come from nodes directly or from location fields on
+    # nodes. For example, a `ClassNode` has an overall location encompassing the
+    # entire class, but it also has a location for the `class` keyword.
+    #
+    # Once the nearest locations are found, it determines which one to attach
+    # to. If it's a trailing comment (a comment on the same line as other source
+    # code), it will favor attaching to the nearest location that occurs before
+    # the comment. Otherwise it will favor attaching to the nearest location
+    # that is after the comment.
+    class Comments
+      # @rbs!
+      #    # An internal interface for a target that comments can be attached
+      #    # to. This is either going to be a NodeTarget or a CommentTarget.
+      #    interface _CommentTarget
+      #      def start_offset: () -> Integer
+      #      def end_offset: () -> Integer
+      #      def encloses?: (Comment) -> bool
+      #      def leading_comment: (Comment) -> void
+      #      def trailing_comment: (Comment) -> void
+      #    end
+
+      # A target for attaching comments that is based on a specific node's
+      # location.
+      class NodeTarget # :nodoc:
+        attr_reader :node #: node
+
+        #: (node node) -> void
+        def initialize(node)
+          @node = node
+        end
+
+        #: () -> Integer
+        def start_offset
+          node.start_offset
+        end
+
+        #: () -> Integer
+        def end_offset
+          node.end_offset
+        end
+
+        #: (Comment comment) -> bool
+        def encloses?(comment)
+          start_offset <= comment.location.start_offset &&
+            comment.location.end_offset <= end_offset
+        end
+
+        #: (Comment comment) -> void
+        def leading_comment(comment)
+          node.location.leading_comment(comment)
+        end
+
+        #: (Comment comment) -> void
+        def trailing_comment(comment)
+          node.location.trailing_comment(comment)
+        end
+      end
+
+      # A target for attaching comments that is based on a location field on a
+      # node. For example, the `end` token of a ClassNode.
+      class LocationTarget # :nodoc:
+        attr_reader :location #: Location
+
+        #: (Location location) -> void
+        def initialize(location)
+          @location = location
+        end
+
+        #: () -> Integer
+        def start_offset
+          location.start_offset
+        end
+
+        #: () -> Integer
+        def end_offset
+          location.end_offset
+        end
+
+        #: (Comment comment) -> bool
+        def encloses?(comment)
+          false
+        end
+
+        #: (Comment comment) -> void
+        def leading_comment(comment)
+          location.leading_comment(comment)
+        end
+
+        #: (Comment comment) -> void
+        def trailing_comment(comment)
+          location.trailing_comment(comment)
+        end
+      end
+
+      # The parse result that we are attaching comments to.
+      attr_reader :parse_result #: ParseResult
+
+      # Create a new Comments object that will attach comments to the given
+      # parse result.
+      #--
+      #: (ParseResult parse_result) -> void
+      def initialize(parse_result)
+        @parse_result = parse_result
+      end
+
+      # Attach the comments to their respective locations in the tree by
+      # mutating the parse result.
+      #--
+      #: () -> void
+      def attach!
+        parse_result.comments.each do |comment|
+          preceding, enclosing, following = nearest_targets(parse_result.value, comment)
+
+          if comment.trailing?
+            if preceding
+              preceding.trailing_comment(comment)
+            else
+              (following || enclosing || NodeTarget.new(parse_result.value)).leading_comment(comment)
+            end
+          else
+            # If a comment exists on its own line, prefer a leading comment.
+            if following
+              following.leading_comment(comment)
+            elsif preceding
+              preceding.trailing_comment(comment)
+            else
+              (enclosing || NodeTarget.new(parse_result.value)).leading_comment(comment)
+            end
+          end
+        end
+      end
+
+      private
+
+      # Responsible for finding the nearest targets to the given comment within
+      # the context of the given encapsulating node.
+      #--
+      #: (node node, Comment comment) -> [_CommentTarget?, _CommentTarget?, _CommentTarget?]
+      def nearest_targets(node, comment)
+        comment_start = comment.location.start_offset
+        comment_end = comment.location.end_offset
+
+        targets = [] #: Array[_CommentTarget]
+        node.comment_targets.map do |value|
+          case value
+          when StatementsNode
+            targets.concat(value.body.map { |node| NodeTarget.new(node) })
+          when Node
+            targets << NodeTarget.new(value)
+          when Location
+            targets << LocationTarget.new(value)
+          end
+        end
+
+        targets.sort_by!(&:start_offset)
+        preceding = nil #: _CommentTarget?
+        following = nil #: _CommentTarget?
+
+        left = 0
+        right = targets.length
+
+        # This is a custom binary search that finds the nearest nodes to the
+        # given comment. When it finds a node that completely encapsulates the
+        # comment, it recurses downward into the tree.
+        while left < right
+          middle = (left + right) / 2
+          target = targets[middle]
+
+          target_start = target.start_offset
+          target_end = target.end_offset
+
+          if target.encloses?(comment)
+            # @type var target: NodeTarget
+            # The comment is completely contained by this target. Abandon the
+            # binary search at this level.
+            return nearest_targets(target.node, comment)
+          end
+
+          if target_end <= comment_start
+            # This target falls completely before the comment. Because we will
+            # never consider this target or any targets before it again, this
+            # target must be the closest preceding target we have encountered so
+            # far.
+            preceding = target
+            left = middle + 1
+            next
+          end
+
+          if comment_end <= target_start
+            # This target falls completely after the comment. Because we will
+            # never consider this target or any targets after it again, this
+            # target must be the closest following target we have encountered so
+            # far.
+            following = target
+            right = middle
+            next
+          end
+
+          # This should only happen if there is a bug in this parser.
+          raise "Comment location overlaps with a target location"
+        end
+
+        [preceding, NodeTarget.new(node), following]
+      end
+    end
+  end
+end
diff --git a/lib/prism/parse_result/errors.rb b/lib/prism/parse_result/errors.rb
new file mode 100644
index 0000000000..388309d23d
--- /dev/null
+++ b/lib/prism/parse_result/errors.rb
@@ -0,0 +1,72 @@
+# frozen_string_literal: true
+# :markup: markdown
+#--
+# rbs_inline: enabled
+
+require "stringio"
+
+module Prism
+  class ParseResult < Result
+    # An object to represent the set of errors on a parse result. This object
+    # can be used to format the errors in a human-readable way.
+    class Errors
+      # The parse result that contains the errors.
+      attr_reader :parse_result #: ParseResult
+
+      # Initialize a new set of errors from the given parse result.
+      #--
+      #: (ParseResult parse_result) -> void
+      def initialize(parse_result)
+        @parse_result = parse_result
+      end
+
+      # Formats the errors in a human-readable way and return them as a string.
+      #--
+      #: () -> String
+      def format
+        error_lines = {} #: Hash[Integer, Array[ParseError]]
+        parse_result.errors.each do |error|
+          location = error.location
+          (location.start_line..location.end_line).each do |line|
+            error_lines[line] ||= []
+            error_lines[line] << error
+          end
+        end
+
+        source_lines = parse_result.source.source.lines
+        source_lines << "" if error_lines.key?(source_lines.size + 1)
+
+        io = StringIO.new
+        source_lines.each.with_index(1) do |line, line_number|
+          io.puts(line)
+
+          (error_lines.delete(line_number) || []).each do |error|
+            location = error.location
+
+            case line_number
+            when location.start_line
+              io.print(" " * location.start_column + "^")
+
+              if location.start_line == location.end_line
+                if location.start_column != location.end_column
+                  io.print("~" * (location.end_column - location.start_column - 1))
+                end
+
+                io.puts(" " + error.message)
+              else
+                io.puts("~" * (line.bytesize - location.start_column))
+              end
+            when location.end_line
+              io.puts("~" * location.end_column + " " + error.message)
+            else
+              io.puts("~" * line.bytesize)
+            end
+          end
+        end
+
+        io.puts
+        io.string
+      end
+    end
+  end
+end
diff --git a/lib/prism/parse_result/newlines.rb b/lib/prism/parse_result/newlines.rb
new file mode 100644
index 0000000000..450c790226
--- /dev/null
+++ b/lib/prism/parse_result/newlines.rb
@@ -0,0 +1,204 @@
+# frozen_string_literal: true
+# :markup: markdown
+#--
+# rbs_inline: enabled
+
+module Prism
+  class ParseResult < Result
+    # The :line tracepoint event gets fired whenever the Ruby VM encounters an
+    # expression on a new line. The types of expressions that can trigger this
+    # event are:
+    #
+    # * if statements
+    # * unless statements
+    # * nodes that are children of statements lists
+    #
+    # In order to keep track of the newlines, we have a list of offsets that
+    # come back from the parser. We assign these offsets to the first nodes that
+    # we find in the tree that are on those lines.
+    #
+    # Note that the logic in this file should be kept in sync with the Java
+    # MarkNewlinesVisitor, since that visitor is responsible for marking the
+    # newlines for JRuby/TruffleRuby.
+    #
+    # This file is autoloaded only when `mark_newlines!` is called, so the
+    # re-opening of the various nodes in this file will only be performed in
+    # that case. We do that to avoid storing the extra `@newline` instance
+    # variable on every node if we don't need it.
+    class Newlines < Visitor
+      # The map of lines indices to whether or not they have been marked as
+      # emitting a newline event.
+      # @rbs @lines: Array[bool]
+
+      # Create a new Newlines visitor with the given newline offsets.
+      #--
+      #: (Integer lines) -> void
+      def initialize(lines)
+        @lines = Array.new(1 + lines, false)
+      end
+
+      # Permit block nodes to mark newlines within themselves.
+      #--
+      #: (BlockNode node) -> void
+      def visit_block_node(node)
+        old_lines = @lines
+        @lines = Array.new(old_lines.size, false)
+
+        begin
+          super(node)
+        ensure
+          @lines = old_lines
+        end
+      end
+
+      # Permit lambda nodes to mark newlines within themselves.
+      #--
+      #: (LambdaNode node) -> void
+      def visit_lambda_node(node)
+        old_lines = @lines
+        @lines = Array.new(old_lines.size, false)
+
+        begin
+          super(node)
+        ensure
+          @lines = old_lines
+        end
+      end
+
+      # Mark if nodes as newlines.
+      #--
+      #: (IfNode node) -> void
+      def visit_if_node(node)
+        node.newline_flag!(@lines)
+        super(node)
+      end
+
+      # Mark unless nodes as newlines.
+      #--
+      #: (UnlessNode node) -> void
+      def visit_unless_node(node)
+        node.newline_flag!(@lines)
+        super(node)
+      end
+
+      # Permit statements lists to mark newlines within themselves.
+      #--
+      #: (StatementsNode node) -> void
+      def visit_statements_node(node)
+        node.body.each do |child|
+          child.newline_flag!(@lines)
+        end
+        super(node)
+      end
+    end
+  end
+
+  class Node
+    # Tracks whether or not this node should emit a newline event when the
+    # instructions that it represents are executed.
+    # @rbs @newline_flag: bool
+
+    #: () -> bool
+    def newline_flag? # :nodoc:
+      !!defined?(@newline_flag)
+    end
+
+    #: (Array[bool] lines) -> void
+    def newline_flag!(lines) # :nodoc:
+      line = location.start_line
+      unless lines[line]
+        lines[line] = true
+        @newline_flag = true
+      end
+    end
+  end
+
+  class BeginNode < Node
+    #: (Array[bool] lines) -> void
+    def newline_flag!(lines) # :nodoc:
+      # Never mark BeginNode with a newline flag, mark children instead.
+    end
+  end
+
+  class ParenthesesNode < Node
+    #: (Array[bool] lines) -> void
+    def newline_flag!(lines) # :nodoc:
+      # Never mark ParenthesesNode with a newline flag, mark children instead.
+    end
+  end
+
+  class IfNode < Node
+    #: (Array[bool] lines) -> void
+    def newline_flag!(lines) # :nodoc:
+      predicate.newline_flag!(lines)
+    end
+  end
+
+  class UnlessNode < Node
+    #: (Array[bool] lines) -> void
+    def newline_flag!(lines) # :nodoc:
+      predicate.newline_flag!(lines)
+    end
+  end
+
+  class UntilNode < Node
+    #: (Array[bool] lines) -> void
+    def newline_flag!(lines) # :nodoc:
+      predicate.newline_flag!(lines)
+    end
+  end
+
+  class WhileNode < Node
+    #: (Array[bool] lines) -> void
+    def newline_flag!(lines) # :nodoc:
+      predicate.newline_flag!(lines)
+    end
+  end
+
+  class RescueModifierNode < Node
+    #: (Array[bool] lines) -> void
+    def newline_flag!(lines) # :nodoc:
+      expression.newline_flag!(lines)
+    end
+  end
+
+  class InterpolatedMatchLastLineNode < Node
+    #: (Array[bool] lines) -> void
+    def newline_flag!(lines) # :nodoc:
+      first = parts.first
+      first.newline_flag!(lines) if first
+    end
+  end
+
+  class InterpolatedRegularExpressionNode < Node
+    #: (Array[bool] lines) -> void
+    def newline_flag!(lines) # :nodoc:
+      first = parts.first
+      first.newline_flag!(lines) if first
+    end
+  end
+
+  class InterpolatedStringNode < Node
+    #: (Array[bool] lines) -> void
+    def newline_flag!(lines) # :nodoc:
+      first = parts.first
+      first.newline_flag!(lines) if first
+    end
+  end
+
+  class InterpolatedSymbolNode < Node
+    #: (Array[bool] lines) -> void
+    def newline_flag!(lines) # :nodoc:
+      first = parts.first
+      first.newline_flag!(lines) if first
+    end
+  end
+
+  class InterpolatedXStringNode < Node
+    #: (Array[bool] lines) -> void
+    def newline_flag!(lines) # :nodoc:
+      first = parts.first
+      first.newline_flag!(lines) if first
+    end
+  end
+end
diff --git a/lib/prism/pattern.rb b/lib/prism/pattern.rb
new file mode 100644
index 0000000000..be0493df05
--- /dev/null
+++ b/lib/prism/pattern.rb
@@ -0,0 +1,314 @@
+# frozen_string_literal: true
+# :markup: markdown
+#--
+# rbs_inline: enabled
+
+module Prism
+  # A pattern is an object that wraps a Ruby pattern matching expression. The
+  # expression would normally be passed to an `in` clause within a `case`
+  # expression or a rightward assignment expression. For example, in the
+  # following snippet:
+  #
+  #     case node
+  #     in ConstantPathNode[ConstantReadNode[name: :Prism], ConstantReadNode[name: :Pattern]]
+  #     end
+  #
+  # the pattern is the <tt>ConstantPathNode[...]</tt> expression.
+  #
+  # The pattern gets compiled into an object that responds to #call by running
+  # the #compile method. This method itself will run back through Prism to
+  # parse the expression into a tree, then walk the tree to generate the
+  # necessary callable objects. For example, if you wanted to compile the
+  # expression above into a callable, you would:
+  #
+  #     callable = Prism::Pattern.new("ConstantPathNode[ConstantReadNode[name: :Prism], ConstantReadNode[name: :Pattern]]").compile
+  #     callable.call(node)
+  #
+  # The callable object returned by #compile is guaranteed to respond to #call
+  # with a single argument, which is the node to match against. It also is
+  # guaranteed to respond to #===, which means it itself can be used in a `case`
+  # expression, as in:
+  #
+  #     case node
+  #     when callable
+  #     end
+  #
+  # If the query given to the initializer cannot be compiled into a valid
+  # matcher (either because of a syntax error or because it is using syntax we
+  # do not yet support) then a Prism::Pattern::CompilationError will be
+  # raised.
+  class Pattern
+    # Raised when the query given to a pattern is either invalid Ruby syntax or
+    # is using syntax that we don't yet support.
+    class CompilationError < StandardError
+      # Create a new CompilationError with the given representation of the node
+      # that caused the error.
+      #--
+      #: (String repr) -> void
+      def initialize(repr) # :nodoc:
+        super(<<~ERROR)
+          prism was unable to compile the pattern you provided into a usable
+          expression. It failed on to understand the node represented by:
+
+          #{repr}
+
+          Note that not all syntax supported by Ruby's pattern matching syntax
+          is also supported by prism's patterns. If you're using some syntax
+          that you believe should be supported, please open an issue on
+          GitHub at https://github.com/ruby/prism/issues/new.
+        ERROR
+      end
+    end
+
+    # The query that this pattern was initialized with.
+    attr_reader :query #: String
+    # @rbs @compiled: Proc?
+
+    # Create a new pattern with the given query. The query should be a string
+    # containing a Ruby pattern matching expression.
+    #--
+    #: (String query) -> void
+    def initialize(query)
+      @query = query
+      @compiled = nil
+    end
+
+    # Compile the query into a callable object that can be used to match against
+    # nodes.
+    #--
+    #: () -> Proc
+    def compile
+      result = Prism.parse("case nil\nin #{query}\nend")
+
+      case_match_node = result.value.statements.body.last
+      raise CompilationError, case_match_node.inspect unless case_match_node.is_a?(CaseMatchNode)
+
+      in_node = case_match_node.conditions.last
+      raise CompilationError, in_node.inspect unless in_node.is_a?(InNode)
+
+      compile_node(in_node.pattern)
+    end
+
+    # Scan the given node and all of its children for nodes that match the
+    # pattern. If a block is given, it will be called with each node that
+    # matches the pattern. If no block is given, an enumerator will be returned
+    # that will yield each node that matches the pattern.
+    #--
+    #: (node root) -> Enumerator[node, void]
+    #: (node root) { (node) -> void } -> void
+    def scan(root, &blk)
+      return to_enum(:scan, root) unless block_given?
+
+      @compiled ||= compile
+      queue = [root]
+
+      while (node = queue.shift)
+        yield node if @compiled.call(node) # steep:ignore
+        queue.concat(node.compact_child_nodes)
+      end
+    end
+
+    private
+
+    # Shortcut for combining two procs into one that returns true if both return
+    # true.
+    #--
+    #: (Proc left, Proc right) -> Proc
+    def combine_and(left, right) # :nodoc:
+      ->(other) { left.call(other) && right.call(other) }
+    end
+
+    # Shortcut for combining two procs into one that returns true if either
+    # returns true.
+    #--
+    #: (Proc left, Proc right) -> Proc
+    def combine_or(left, right) # :nodoc:
+      ->(other) { left.call(other) || right.call(other) }
+    end
+
+    # Raise an error because the given node is not supported. Note purposefully
+    # not typing this method since it is a no return method that Steep does not
+    # understand.
+    #--
+    #: (node node) -> bot
+    def compile_error(node) # :nodoc:
+      raise CompilationError, node.inspect
+    end
+
+    # in [foo, bar, baz]
+    #--
+    #: (ArrayPatternNode node) -> Proc
+    def compile_array_pattern_node(node) # :nodoc:
+      compile_error(node) if !node.rest.nil? || node.posts.any?
+
+      constant = node.constant
+      compiled_constant = compile_node(constant) if constant
+
+      preprocessed = node.requireds.map { |required| compile_node(required) }
+
+      compiled_requireds = ->(other) do
+        deconstructed = other.deconstruct
+
+        deconstructed.length == preprocessed.length &&
+          preprocessed
+            .zip(deconstructed)
+            .all? { |(matcher, value)| matcher.call(value) }
+      end
+
+      if compiled_constant
+        combine_and(compiled_constant, compiled_requireds)
+      else
+        compiled_requireds
+      end
+    end
+
+    # in foo | bar
+    #--
+    #: (AlternationPatternNode node) -> Proc
+    def compile_alternation_pattern_node(node) # :nodoc:
+      combine_or(compile_node(node.left), compile_node(node.right))
+    end
+
+    # in Prism::ConstantReadNode
+    #--
+    #: (ConstantPathNode node) -> Proc
+    def compile_constant_path_node(node) # :nodoc:
+      parent = node.parent
+
+      if parent.is_a?(ConstantReadNode) && parent.slice == "Prism"
+        name = node.name
+        raise CompilationError, node.inspect if name.nil?
+
+        compile_constant_name(node, name)
+      else
+        compile_error(node)
+      end
+    end
+
+    # in ConstantReadNode
+    # in String
+    #--
+    #: (ConstantReadNode node) -> Proc
+    def compile_constant_read_node(node) # :nodoc:
+      compile_constant_name(node, node.name)
+    end
+
+    # Compile a name associated with a constant.
+    #--
+    #: ((ConstantPathNode | ConstantReadNode) node, Symbol name) -> Proc
+    def compile_constant_name(node, name) # :nodoc:
+      if Prism.const_defined?(name, false)
+        clazz = Prism.const_get(name)
+
+        ->(other) { clazz === other }
+      elsif Object.const_defined?(name, false)
+        clazz = Object.const_get(name)
+
+        ->(other) { clazz === other }
+      else
+        compile_error(node)
+      end
+    end
+
+    # in InstanceVariableReadNode[name: Symbol]
+    # in { name: Symbol }
+    #--
+    #: (HashPatternNode node) -> Proc
+    def compile_hash_pattern_node(node) # :nodoc:
+      compile_error(node) if node.rest
+
+      if (constant = node.constant)
+        compiled_constant = compile_node(constant)
+      end
+
+      preprocessed =
+        node.elements.to_h do |element|
+          key = element.key
+          if key.is_a?(SymbolNode)
+            [key.unescaped.to_sym, compile_node(element.value)]
+          else
+            raise CompilationError, element.inspect
+          end
+        end
+
+      compiled_keywords = ->(other) do
+        deconstructed = other.deconstruct_keys(preprocessed.keys)
+
+        preprocessed.all? do |keyword, matcher|
+          deconstructed.key?(keyword) && matcher.call(deconstructed[keyword])
+        end
+      end
+
+      if compiled_constant
+        combine_and(compiled_constant, compiled_keywords)
+      else
+        compiled_keywords
+      end
+    end
+
+    # in nil
+    #--
+    #: (NilNode node) -> Proc
+    def compile_nil_node(node) # :nodoc:
+      ->(attribute) { attribute.nil? }
+    end
+
+    # in /foo/
+    #--
+    #: (RegularExpressionNode node) -> Proc
+    def compile_regular_expression_node(node) # :nodoc:
+      regexp = Regexp.new(node.unescaped, node.closing[1..])
+
+      ->(attribute) { regexp === attribute }
+    end
+
+    # in ""
+    # in "foo"
+    #--
+    #: (StringNode node) -> Proc
+    def compile_string_node(node) # :nodoc:
+      string = node.unescaped
+
+      ->(attribute) { string === attribute }
+    end
+
+    # in :+
+    # in :foo
+    #--
+    #: (SymbolNode node) -> Proc
+    def compile_symbol_node(node) # :nodoc:
+      symbol = node.unescaped.to_sym
+
+      ->(attribute) { symbol === attribute }
+    end
+
+    # Compile any kind of node. Dispatch out to the individual compilation
+    # methods based on the type of node.
+    #--
+    #: (node node) -> Proc
+    def compile_node(node) # :nodoc:
+      case node
+      when AlternationPatternNode
+        compile_alternation_pattern_node(node)
+      when ArrayPatternNode
+        compile_array_pattern_node(node)
+      when ConstantPathNode
+        compile_constant_path_node(node)
+      when ConstantReadNode
+        compile_constant_read_node(node)
+      when HashPatternNode
+        compile_hash_pattern_node(node)
+      when NilNode
+        compile_nil_node(node)
+      when RegularExpressionNode
+        compile_regular_expression_node(node)
+      when StringNode
+        compile_string_node(node)
+      when SymbolNode
+        compile_symbol_node(node)
+      else
+        compile_error(node)
+      end
+    end
+  end
+end
diff --git a/lib/prism/polyfill/append_as_bytes.rb b/lib/prism/polyfill/append_as_bytes.rb
new file mode 100644
index 0000000000..24218bd171
--- /dev/null
+++ b/lib/prism/polyfill/append_as_bytes.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+# Polyfill for String#append_as_bytes, which didn't exist until Ruby 3.4.
+if !("".respond_to?(:append_as_bytes))
+  String.include(
+    Module.new {
+      def append_as_bytes(*args)
+        args.each do |arg|
+          arg = Integer === arg ? [arg].pack("C") : arg.b
+          self.<<(arg) # steep:ignore
+        end
+      end
+    }
+  )
+end
diff --git a/lib/prism/polyfill/byteindex.rb b/lib/prism/polyfill/byteindex.rb
new file mode 100644
index 0000000000..98c6089f14
--- /dev/null
+++ b/lib/prism/polyfill/byteindex.rb
@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+# Polyfill for String#byteindex, which didn't exist until Ruby 3.2.
+if !("".respond_to?(:byteindex))
+  String.include(
+    Module.new {
+      def byteindex(needle, offset = 0)
+        charindex = index(needle, offset)
+        slice(0...charindex).bytesize if charindex
+      end
+    }
+  )
+end
diff --git a/lib/prism/polyfill/scan_byte.rb b/lib/prism/polyfill/scan_byte.rb
new file mode 100644
index 0000000000..9276e509fc
--- /dev/null
+++ b/lib/prism/polyfill/scan_byte.rb
@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+require "strscan"
+
+# Polyfill for StringScanner#scan_byte, which didn't exist until Ruby 3.4.
+if !(StringScanner.method_defined?(:scan_byte))
+  StringScanner.include(
+    Module.new {
+      def scan_byte # :nodoc:
+        get_byte&.b&.ord
+      end
+    }
+  )
+end
diff --git a/lib/prism/polyfill/unpack1.rb b/lib/prism/polyfill/unpack1.rb
new file mode 100644
index 0000000000..3fa9b5a0c5
--- /dev/null
+++ b/lib/prism/polyfill/unpack1.rb
@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+# Polyfill for String#unpack1 with the offset parameter. Not all Ruby engines
+# have Method#parameters implemented, so we check the arity instead if
+# necessary.
+if (unpack1 = String.instance_method(:unpack1)).respond_to?(:parameters) ? unpack1.parameters.none? { |_, name| name == :offset } : (unpack1.arity == 1)
+  String.prepend(
+    Module.new {
+      def unpack1(format, offset: 0) # :nodoc:
+        offset == 0 ? super(format) : self[offset..].unpack1(format) # steep:ignore
+      end
+    }
+  )
+end
diff --git a/lib/prism/polyfill/warn.rb b/lib/prism/polyfill/warn.rb
new file mode 100644
index 0000000000..76a4264623
--- /dev/null
+++ b/lib/prism/polyfill/warn.rb
@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+# Polyfill for Kernel#warn with the category parameter. Not all Ruby engines
+# have Method#parameters implemented, so we check the arity instead if
+# necessary.
+if (method = Kernel.instance_method(:warn)).respond_to?(:parameters) ? method.parameters.none? { |_, name| name == :category } : (method.arity == -1)
+  Kernel.prepend(
+    Module.new {
+      def warn(*msgs, uplevel: nil, category: nil) # :nodoc:
+        case uplevel
+        when nil
+          super(*msgs)
+        when Integer
+          super(*msgs, uplevel: uplevel + 1)
+        else
+          super(*msgs, uplevel: uplevel.to_int + 1)
+        end
+      end
+    }
+  )
+
+  Object.prepend(
+    Module.new {
+      def warn(*msgs, uplevel: nil, category: nil) # :nodoc:
+        case uplevel
+        when nil
+          super(*msgs)
+        when Integer
+          super(*msgs, uplevel: uplevel + 1)
+        else
+          super(*msgs, uplevel: uplevel.to_int + 1)
+        end
+      end
+    }
+  )
+end
diff --git a/lib/prism/prism.gemspec b/lib/prism/prism.gemspec
new file mode 100644
index 0000000000..aac056b3f8
--- /dev/null
+++ b/lib/prism/prism.gemspec
@@ -0,0 +1,232 @@
+# frozen_string_literal: true
+
+Gem::Specification.new do |spec|
+  spec.name = "prism"
+  spec.version = "1.9.0"
+  spec.authors = ["Shopify"]
+  spec.email = ["ruby@shopify.com"]
+
+  spec.summary = "Prism Ruby parser"
+  spec.homepage = "https://github.com/ruby/prism"
+  spec.license = "MIT"
+
+  spec.required_ruby_version = ">= 2.7.0"
+
+  spec.require_paths = ["lib"]
+  spec.files = [
+    "BSDmakefile",
+    "CHANGELOG.md",
+    "CODE_OF_CONDUCT.md",
+    "CONTRIBUTING.md",
+    "LICENSE.md",
+    "Makefile",
+    "README.md",
+    "config.yml",
+    "docs/build_system.md",
+    "docs/configuration.md",
+    "docs/cruby_compilation.md",
+    "docs/design.md",
+    "docs/encoding.md",
+    "docs/fuzzing.md",
+    "docs/heredocs.md",
+    "docs/javascript.md",
+    "docs/local_variable_depth.md",
+    "docs/mapping.md",
+    "docs/parser_translation.md",
+    "docs/parsing_rules.md",
+    "docs/releasing.md",
+    "docs/relocation.md",
+    "docs/ripper_translation.md",
+    "docs/ruby_api.md",
+    "docs/ruby_parser_translation.md",
+    "docs/serialization.md",
+    "docs/testing.md",
+    "ext/prism/api_node.c",
+    "ext/prism/extconf.rb",
+    "ext/prism/extension.c",
+    "ext/prism/extension.h",
+    "include/prism.h",
+    "include/prism/compiler/accel.h",
+    "include/prism/compiler/align.h",
+    "include/prism/compiler/exported.h",
+    "include/prism/compiler/fallthrough.h",
+    "include/prism/compiler/filesystem.h",
+    "include/prism/compiler/flex_array.h",
+    "include/prism/compiler/force_inline.h",
+    "include/prism/compiler/format.h",
+    "include/prism/compiler/inline.h",
+    "include/prism/compiler/nodiscard.h",
+    "include/prism/compiler/nonnull.h",
+    "include/prism/compiler/unused.h",
+    "include/prism/internal/allocator.h",
+    "include/prism/internal/allocator_debug.h",
+    "include/prism/internal/arena.h",
+    "include/prism/internal/bit.h",
+    "include/prism/internal/buffer.h",
+    "include/prism/internal/char.h",
+    "include/prism/internal/comments.h",
+    "include/prism/internal/constant_pool.h",
+    "include/prism/internal/diagnostic.h",
+    "include/prism/internal/encoding.h",
+    "include/prism/internal/integer.h",
+    "include/prism/internal/isinf.h",
+    "include/prism/internal/line_offset_list.h",
+    "include/prism/internal/list.h",
+    "include/prism/internal/magic_comments.h",
+    "include/prism/internal/memchr.h",
+    "include/prism/internal/node.h",
+    "include/prism/internal/options.h",
+    "include/prism/internal/parser.h",
+    "include/prism/internal/regexp.h",
+    "include/prism/internal/serialize.h",
+    "include/prism/internal/source.h",
+    "include/prism/internal/static_literals.h",
+    "include/prism/internal/strncasecmp.h",
+    "include/prism/internal/stringy.h",
+    "include/prism/internal/strpbrk.h",
+    "include/prism/internal/tokens.h",
+    "include/prism/arena.h",
+    "include/prism/ast.h",
+    "include/prism/buffer.h",
+    "include/prism/comments.h",
+    "include/prism/constant_pool.h",
+    "include/prism/diagnostic.h",
+    "include/prism/excludes.h",
+    "include/prism/integer.h",
+    "include/prism/json.h",
+    "include/prism/line_offset_list.h",
+    "include/prism/magic_comments.h",
+    "include/prism/node.h",
+    "include/prism/options.h",
+    "include/prism/parser.h",
+    "include/prism/prettyprint.h",
+    "include/prism/serialize.h",
+    "include/prism/source.h",
+    "include/prism/stream.h",
+    "include/prism/string_query.h",
+    "include/prism/stringy.h",
+    "include/prism/version.h",
+    "lib/prism.rb",
+    "lib/prism/compiler.rb",
+    "lib/prism/desugar_compiler.rb",
+    "lib/prism/dispatcher.rb",
+    "lib/prism/dot_visitor.rb",
+    "lib/prism/dsl.rb",
+    "lib/prism/ffi.rb",
+    "lib/prism/inspect_visitor.rb",
+    "lib/prism/lex_compat.rb",
+    "lib/prism/mutation_compiler.rb",
+    "lib/prism/node_ext.rb",
+    "lib/prism/node_find.rb",
+    "lib/prism/node.rb",
+    "lib/prism/parse_result.rb",
+    "lib/prism/parse_result/comments.rb",
+    "lib/prism/parse_result/errors.rb",
+    "lib/prism/parse_result/newlines.rb",
+    "lib/prism/pattern.rb",
+    "lib/prism/polyfill/append_as_bytes.rb",
+    "lib/prism/polyfill/byteindex.rb",
+    "lib/prism/polyfill/scan_byte.rb",
+    "lib/prism/polyfill/unpack1.rb",
+    "lib/prism/polyfill/warn.rb",
+    "lib/prism/reflection.rb",
+    "lib/prism/relocation.rb",
+    "lib/prism/serialize.rb",
+    "lib/prism/string_query.rb",
+    "lib/prism/translation.rb",
+    "lib/prism/translation/parser.rb",
+    "lib/prism/translation/parser_current.rb",
+    "lib/prism/translation/parser_versions.rb",
+    "lib/prism/translation/parser/builder.rb",
+    "lib/prism/translation/parser/compiler.rb",
+    "lib/prism/translation/parser/lexer.rb",
+    "lib/prism/translation/ripper.rb",
+    "lib/prism/translation/ripper/filter.rb",
+    "lib/prism/translation/ripper/lexer.rb",
+    "lib/prism/translation/ripper/sexp.rb",
+    "lib/prism/translation/ripper/shim.rb",
+    "lib/prism/translation/ruby_parser.rb",
+    "lib/prism/visitor.rb",
+    "prism.gemspec",
+    "rbi/generated/prism.rbi",
+    "rbi/generated/prism/compiler.rbi",
+    "rbi/generated/prism/desugar_compiler.rbi",
+    "rbi/generated/prism/dispatcher.rbi",
+    "rbi/generated/prism/dot_visitor.rbi",
+    "rbi/generated/prism/dsl.rbi",
+    "rbi/generated/prism/inspect_visitor.rbi",
+    "rbi/generated/prism/lex_compat.rbi",
+    "rbi/generated/prism/mutation_compiler.rbi",
+    "rbi/generated/prism/node.rbi",
+    "rbi/generated/prism/node_ext.rbi",
+    "rbi/generated/prism/node_find.rbi",
+    "rbi/generated/prism/parse_result.rbi",
+    "rbi/generated/prism/pattern.rbi",
+    "rbi/generated/prism/reflection.rbi",
+    "rbi/generated/prism/relocation.rbi",
+    "rbi/generated/prism/serialize.rbi",
+    "rbi/generated/prism/string_query.rbi",
+    "rbi/generated/prism/translation.rbi",
+    "rbi/generated/prism/visitor.rbi",
+    "rbi/generated/prism/parse_result/comments.rbi",
+    "rbi/generated/prism/parse_result/errors.rbi",
+    "rbi/generated/prism/parse_result/newlines.rbi",
+    "rbi/prism/translation/parser.rbi",
+    "rbi/prism/translation/parser_versions.rbi",
+    "rbi/prism/translation/ripper.rbi",
+    "rbi/rubyvm/node_find.rbi",
+    "sig/generated/prism.rbs",
+    "sig/generated/prism/compiler.rbs",
+    "sig/generated/prism/desugar_compiler.rbs",
+    "sig/generated/prism/dispatcher.rbs",
+    "sig/generated/prism/dot_visitor.rbs",
+    "sig/generated/prism/dsl.rbs",
+    "sig/generated/prism/inspect_visitor.rbs",
+    "sig/generated/prism/lex_compat.rbs",
+    "sig/generated/prism/mutation_compiler.rbs",
+    "sig/generated/prism/node.rbs",
+    "sig/generated/prism/node_ext.rbs",
+    "sig/generated/prism/node_find.rbs",
+    "sig/generated/prism/parse_result.rbs",
+    "sig/generated/prism/pattern.rbs",
+    "sig/generated/prism/reflection.rbs",
+    "sig/generated/prism/relocation.rbs",
+    "sig/generated/prism/serialize.rbs",
+    "sig/generated/prism/string_query.rbs",
+    "sig/generated/prism/translation.rbs",
+    "sig/generated/prism/visitor.rbs",
+    "sig/generated/prism/parse_result/comments.rbs",
+    "sig/generated/prism/parse_result/errors.rbs",
+    "sig/generated/prism/parse_result/newlines.rbs",
+    "src/arena.c",
+    "src/buffer.c",
+    "src/char.c",
+    "src/constant_pool.c",
+    "src/diagnostic.c",
+    "src/encoding.c",
+    "src/integer.c",
+    "src/json.c",
+    "src/line_offset_list.c",
+    "src/list.c",
+    "src/memchr.c",
+    "src/node.c",
+    "src/options.c",
+    "src/parser.c",
+    "src/prettyprint.c",
+    "src/prism.c",
+    "src/regexp.c",
+    "src/serialize.c",
+    "src/source.c",
+    "src/static_literals.c",
+    "src/string_query.c",
+    "src/stringy.c",
+    "src/strncasecmp.c",
+    "src/strpbrk.c",
+    "src/tokens.c"
+  ]
+
+  spec.extensions = ["ext/prism/extconf.rb"]
+  spec.metadata["allowed_push_host"] = "https://rubygems.org"
+  spec.metadata["source_code_uri"] = "https://github.com/ruby/prism"
+  spec.metadata["changelog_uri"] = "https://github.com/ruby/prism/blob/main/CHANGELOG.md"
+end
diff --git a/lib/prism/relocation.rb b/lib/prism/relocation.rb
new file mode 100644
index 0000000000..af0f792827
--- /dev/null
+++ b/lib/prism/relocation.rb
@@ -0,0 +1,665 @@
+# frozen_string_literal: true
+# :markup: markdown
+#--
+# rbs_inline: enabled
+
+module Prism
+  # Prism parses deterministically for the same input. This provides a nice
+  # property that is exposed through the #node_id API on nodes. Effectively this
+  # means that for the same input, these values will remain consistent every
+  # time the source is parsed. This means we can reparse the source same with a
+  # #node_id value and find the exact same node again.
+  #
+  # The Relocation module provides an API around this property. It allows you to
+  # "save" nodes and locations using a minimal amount of memory (just the
+  # node_id and a field identifier) and then reify them later.
+  module Relocation
+    # @rbs!
+    #    type entry_value = untyped
+    #    type entry_values = Hash[Symbol, entry_value]
+    #
+    #    interface _Value
+    #      def start_line: () -> Integer
+    #      def end_line: () -> Integer
+    #      def start_offset: () -> Integer
+    #      def end_offset: () -> Integer
+    #      def start_character_offset: () -> Integer
+    #      def end_character_offset: () -> Integer
+    #      def cached_start_code_units_offset: (_CodeUnitsCache cache) -> Integer
+    #      def cached_end_code_units_offset: (_CodeUnitsCache cache) -> Integer
+    #      def start_column: () -> Integer
+    #      def end_column: () -> Integer
+    #      def start_character_column: () -> Integer
+    #      def end_character_column: () -> Integer
+    #      def cached_start_code_units_column: (_CodeUnitsCache cache) -> Integer
+    #      def cached_end_code_units_column: (_CodeUnitsCache cache) -> Integer
+    #      def leading_comments: () -> Array[Comment]
+    #      def trailing_comments: () -> Array[Comment]
+    #    end
+    #
+    #    interface _Field
+    #      def fields: (_Value value) -> entry_values
+    #    end
+
+    # An entry in a repository that will lazily reify its values when they are
+    # first accessed.
+    class Entry
+      # Raised if a value that could potentially be on an entry is missing
+      # because it was either not configured on the repository or it has not yet
+      # been fetched.
+      class MissingValueError < StandardError
+      end
+
+      # @rbs @repository: Repository?
+      # @rbs @values: Hash[Symbol, untyped]?
+
+      # Initialize a new entry with the given repository.
+      #--
+      #: (Repository repository) -> void
+      def initialize(repository)
+        @repository = repository
+        @values = nil
+      end
+
+      # Fetch the filepath of the value.
+      #--
+      #: () -> String
+      def filepath
+        fetch_value(:filepath)
+      end
+
+      # Fetch the start line of the value.
+      #--
+      #: () -> Integer
+      def start_line
+        fetch_value(:start_line)
+      end
+
+      # Fetch the end line of the value.
+      #--
+      #: () -> Integer
+      def end_line
+        fetch_value(:end_line)
+      end
+
+      # Fetch the start byte offset of the value.
+      #--
+      #: () -> Integer
+      def start_offset
+        fetch_value(:start_offset)
+      end
+
+      # Fetch the end byte offset of the value.
+      #--
+      #: () -> Integer
+      def end_offset
+        fetch_value(:end_offset)
+      end
+
+      # Fetch the start character offset of the value.
+      #--
+      #: () -> Integer
+      def start_character_offset
+        fetch_value(:start_character_offset)
+      end
+
+      # Fetch the end character offset of the value.
+      #--
+      #: () -> Integer
+      def end_character_offset
+        fetch_value(:end_character_offset)
+      end
+
+      # Fetch the start code units offset of the value, for the encoding that
+      # was configured on the repository.
+      #--
+      #: () -> Integer
+      def start_code_units_offset
+        fetch_value(:start_code_units_offset)
+      end
+
+      # Fetch the end code units offset of the value, for the encoding that was
+      # configured on the repository.
+      #--
+      #: () -> Integer
+      def end_code_units_offset
+        fetch_value(:end_code_units_offset)
+      end
+
+      # Fetch the start byte column of the value.
+      #--
+      #: () -> Integer
+      def start_column
+        fetch_value(:start_column)
+      end
+
+      # Fetch the end byte column of the value.
+      #--
+      #: () -> Integer
+      def end_column
+        fetch_value(:end_column)
+      end
+
+      # Fetch the start character column of the value.
+      #--
+      #: () -> Integer
+      def start_character_column
+        fetch_value(:start_character_column)
+      end
+
+      # Fetch the end character column of the value.
+      #--
+      #: () -> Integer
+      def end_character_column
+        fetch_value(:end_character_column)
+      end
+
+      # Fetch the start code units column of the value, for the encoding that
+      # was configured on the repository.
+      #--
+      #: () -> Integer
+      def start_code_units_column
+        fetch_value(:start_code_units_column)
+      end
+
+      # Fetch the end code units column of the value, for the encoding that was
+      # configured on the repository.
+      #--
+      #: () -> Integer
+      def end_code_units_column
+        fetch_value(:end_code_units_column)
+      end
+
+      # Fetch the leading comments of the value.
+      #--
+      #: () -> Array[CommentsField::Comment]
+      def leading_comments
+        fetch_value(:leading_comments)
+      end
+
+      # Fetch the trailing comments of the value.
+      #--
+      #: () -> Array[CommentsField::Comment]
+      def trailing_comments
+        fetch_value(:trailing_comments)
+      end
+
+      # Fetch the leading and trailing comments of the value.
+      #--
+      #: () -> Array[CommentsField::Comment]
+      def comments
+        [*leading_comments, *trailing_comments]
+      end
+
+      # Reify the values on this entry with the given values. This is an
+      # internal-only API that is called from the repository when it is time to
+      # reify the values.
+      #--
+      #: (entry_values values) -> void
+      def reify!(values) # :nodoc:
+        @repository = nil
+        @values = values
+      end
+
+      private
+
+      # Fetch a value from the entry, raising an error if it is missing.
+      #--
+      #: (Symbol name) -> entry_value
+      def fetch_value(name)
+        values.fetch(name) do
+          raise MissingValueError, "No value for #{name}, make sure the " \
+            "repository has been properly configured"
+        end
+      end
+
+      # Return the values from the repository, reifying them if necessary.
+      #--
+      #: () -> entry_values
+      def values
+        @values || (@repository&.reify!; @values) #: entry_values
+      end
+    end
+
+    # Represents the source of a repository that will be reparsed.
+    class Source
+      # The value that will need to be reparsed.
+      attr_reader :value #: untyped
+
+      # Initialize the source with the given value.
+      #--
+      #: (untyped value) -> void
+      def initialize(value)
+        @value = value
+      end
+
+      # Reparse the value and return the parse result.
+      #--
+      #: () -> ParseResult
+      def result
+        raise NotImplementedError, "Subclasses must implement #result"
+      end
+
+      # Create a code units cache for the given encoding.
+      #--
+      #: (Encoding encoding) -> _CodeUnitsCache
+      def code_units_cache(encoding)
+        result.code_units_cache(encoding)
+      end
+    end
+
+    # A source that is represented by a file path.
+    class SourceFilepath < Source
+      # Reparse the file and return the parse result.
+      #--
+      #: () -> ParseResult
+      def result
+        Prism.parse_file(value)
+      end
+    end
+
+    # A source that is represented by a string.
+    class SourceString < Source
+      # Reparse the string and return the parse result.
+      #--
+      #: () -> ParseResult
+      def result
+        Prism.parse(value)
+      end
+    end
+
+    # A field that represents the file path.
+    class FilepathField
+      # The file path that this field represents.
+      attr_reader :value #: String
+
+      # Initialize a new field with the given file path.
+      #--
+      #: (String value) -> void
+      def initialize(value)
+        @value = value
+      end
+
+      # Fetch the file path.
+      #--
+      #: (_Value _value) -> entry_values
+      def fields(_value)
+        { filepath: value }
+      end
+    end
+
+    # A field representing the start and end lines.
+    class LinesField
+      # Fetches the start and end line of a value.
+      #--
+      #: (_Value value) -> entry_values
+      def fields(value)
+        { start_line: value.start_line, end_line: value.end_line }
+      end
+    end
+
+    # A field representing the start and end byte offsets.
+    class OffsetsField
+      # Fetches the start and end byte offset of a value.
+      #--
+      #: (_Value value) -> entry_values
+      def fields(value)
+        { start_offset: value.start_offset, end_offset: value.end_offset }
+      end
+    end
+
+    # A field representing the start and end character offsets.
+    class CharacterOffsetsField
+      # Fetches the start and end character offset of a value.
+      #--
+      #: (_Value value) -> entry_values
+      def fields(value)
+        {
+          start_character_offset: value.start_character_offset,
+          end_character_offset: value.end_character_offset
+        }
+      end
+    end
+
+    # A field representing the start and end code unit offsets.
+    class CodeUnitOffsetsField
+      # A pointer to the repository object that is used for lazily creating a
+      # code units cache.
+      attr_reader :repository #: Repository
+
+      # The associated encoding for the code units.
+      attr_reader :encoding #: Encoding
+
+      # @rbs @cache: _CodeUnitsCache?
+
+      # Initialize a new field with the associated repository and encoding.
+      #--
+      #: (Repository repository, Encoding encoding) -> void
+      def initialize(repository, encoding)
+        @repository = repository
+        @encoding = encoding
+        @cache = nil
+      end
+
+      # Fetches the start and end code units offset of a value for a particular
+      # encoding.
+      #--
+      #: (_Value value) -> entry_values
+      def fields(value)
+        {
+          start_code_units_offset: value.cached_start_code_units_offset(cache),
+          end_code_units_offset: value.cached_end_code_units_offset(cache)
+        }
+      end
+
+      private
+
+      # Lazily create a code units cache for the associated encoding.
+      #--
+      #: () -> _CodeUnitsCache
+      def cache
+        @cache ||= repository.code_units_cache(encoding)
+      end
+    end
+
+    # A field representing the start and end byte columns.
+    class ColumnsField
+      # Fetches the start and end byte column of a value.
+      #--
+      #: (_Value value) -> entry_values
+      def fields(value)
+        { start_column: value.start_column, end_column: value.end_column }
+      end
+    end
+
+    # A field representing the start and end character columns.
+    class CharacterColumnsField
+      # Fetches the start and end character column of a value.
+      #--
+      #: (_Value value) -> entry_values
+      def fields(value)
+        {
+          start_character_column: value.start_character_column,
+          end_character_column: value.end_character_column
+        }
+      end
+    end
+
+    # A field representing the start and end code unit columns for a specific
+    # encoding.
+    class CodeUnitColumnsField
+      # The repository object that is used for lazily creating a code units
+      # cache.
+      attr_reader :repository #: Repository
+
+      # The associated encoding for the code units.
+      attr_reader :encoding #: Encoding
+
+      # @rbs @cache: _CodeUnitsCache?
+
+      # Initialize a new field with the associated repository and encoding.
+      #--
+      #: (Repository repository, Encoding encoding) -> void
+      def initialize(repository, encoding)
+        @repository = repository
+        @encoding = encoding
+        @cache = nil
+      end
+
+      # Fetches the start and end code units column of a value for a particular
+      # encoding.
+      #--
+      #: (_Value value) -> entry_values
+      def fields(value)
+        {
+          start_code_units_column: value.cached_start_code_units_column(cache),
+          end_code_units_column: value.cached_end_code_units_column(cache)
+        }
+      end
+
+      private
+
+      # Lazily create a code units cache for the associated encoding.
+      #--
+      #: () -> _CodeUnitsCache
+      def cache
+        @cache ||= repository.code_units_cache(encoding)
+      end
+    end
+
+    # An abstract field used as the parent class of the two comments fields.
+    class CommentsField
+      # An object that represents a slice of a comment.
+      class Comment
+        # The slice of the comment.
+        attr_reader :slice #: String
+
+        # Initialize a new comment with the given slice.
+        #
+        #: (String slice) -> void
+        def initialize(slice)
+          @slice = slice
+        end
+      end
+
+      private
+
+      # Create comment objects from the given values.
+      #--
+      #: (entry_value values) -> Array[Comment]
+      def comments(values)
+        values.map { |value| Comment.new(value.slice) }
+      end
+    end
+
+    # A field representing the leading comments.
+    class LeadingCommentsField < CommentsField
+      # Fetches the leading comments of a value.
+      #--
+      #: (_Value value) -> entry_values
+      def fields(value)
+        { leading_comments: comments(value.leading_comments) }
+      end
+    end
+
+    # A field representing the trailing comments.
+    class TrailingCommentsField < CommentsField
+      # Fetches the trailing comments of a value.
+      #--
+      #: (_Value value) -> entry_values
+      def fields(value)
+        { trailing_comments: comments(value.trailing_comments) }
+      end
+    end
+
+    # A repository is a configured collection of fields and a set of entries
+    # that knows how to reparse a source and reify the values.
+    class Repository
+      # Raised when multiple fields of the same type are configured on the same
+      # repository.
+      class ConfigurationError < StandardError
+      end
+
+      # The source associated with this repository. This will be either a
+      # SourceFilepath (the most common use case) or a SourceString.
+      attr_reader :source #: Source
+
+      # The fields that have been configured on this repository.
+      attr_reader :fields #: Hash[Symbol, _Field]
+
+      # The entries that have been saved on this repository.
+      attr_reader :entries #: Hash[Integer, Hash[Symbol, Entry]]
+
+      # Initialize a new repository with the given source.
+      #--
+      #: (Source source) -> void
+      def initialize(source)
+        @source = source
+        @fields = {}
+        @entries = Hash.new { |hash, node_id| hash[node_id] = {} }
+      end
+
+      # Create a code units cache for the given encoding from the source.
+      #--
+      #: (Encoding encoding) -> _CodeUnitsCache
+      def code_units_cache(encoding)
+        source.code_units_cache(encoding)
+      end
+
+      # Configure the filepath field for this repository and return self.
+      #--
+      #: () -> self
+      def filepath
+        raise ConfigurationError, "Can only specify filepath for a filepath source" unless source.is_a?(SourceFilepath)
+        field(:filepath, FilepathField.new(source.value))
+      end
+
+      # Configure the lines field for this repository and return self.
+      #--
+      #: () -> self
+      def lines
+        field(:lines, LinesField.new)
+      end
+
+      # Configure the offsets field for this repository and return self.
+      #--
+      #: () -> self
+      def offsets
+        field(:offsets, OffsetsField.new)
+      end
+
+      # Configure the character offsets field for this repository and return
+      # self.
+      #--
+      #: () -> self
+      def character_offsets
+        field(:character_offsets, CharacterOffsetsField.new)
+      end
+
+      # Configure the code unit offsets field for this repository for a specific
+      # encoding and return self.
+      #--
+      #: (Encoding encoding) -> self
+      def code_unit_offsets(encoding)
+        field(:code_unit_offsets, CodeUnitOffsetsField.new(self, encoding))
+      end
+
+      # Configure the columns field for this repository and return self.
+      #--
+      #: () -> self
+      def columns
+        field(:columns, ColumnsField.new)
+      end
+
+      # Configure the character columns field for this repository and return
+      # self.
+      #--
+      #: () -> self
+      def character_columns
+        field(:character_columns, CharacterColumnsField.new)
+      end
+
+      # Configure the code unit columns field for this repository for a specific
+      # encoding and return self.
+      #--
+      #: (Encoding encoding) -> self
+      def code_unit_columns(encoding)
+        field(:code_unit_columns, CodeUnitColumnsField.new(self, encoding))
+      end
+
+      # Configure the leading comments field for this repository and return
+      # self.
+      #--
+      #: () -> self
+      def leading_comments
+        field(:leading_comments, LeadingCommentsField.new)
+      end
+
+      # Configure the trailing comments field for this repository and return
+      # self.
+      #--
+      #: () -> self
+      def trailing_comments
+        field(:trailing_comments, TrailingCommentsField.new)
+      end
+
+      # Configure both the leading and trailing comment fields for this
+      # repository and return self.
+      #--
+      #: () -> self
+      def comments
+        leading_comments.trailing_comments
+      end
+
+      # This method is called from nodes and locations when they want to enter
+      # themselves into the repository. It it internal-only and meant to be
+      # called from the #save* APIs.
+      #--
+      #: (Integer node_id, Symbol field_name) -> Entry
+      def enter(node_id, field_name) # :nodoc:
+        entry = Entry.new(self)
+        @entries[node_id][field_name] = entry
+        entry
+      end
+
+      # This method is called from the entries in the repository when they need
+      # to reify their values. It is internal-only and meant to be called from
+      # the various value APIs.
+      #--
+      #: () -> void
+      def reify! # :nodoc:
+        result = source.result
+
+        # Attach the comments if they have been requested as part of the
+        # configuration of this repository.
+        if fields.key?(:leading_comments) || fields.key?(:trailing_comments)
+          result.attach_comments!
+        end
+
+        queue = [result.value] #: Array[Prism::node]
+        while (node = queue.shift)
+          @entries[node.node_id].each do |field_name, entry|
+            value = node.public_send(field_name)
+            values = {} #: entry_values
+
+            fields.each_value do |field|
+              values.merge!(field.fields(value))
+            end
+
+            entry.reify!(values)
+          end
+
+          queue.concat(node.compact_child_nodes)
+        end
+
+        @entries.clear
+      end
+
+      private
+
+      # Append the given field to the repository and return the repository so
+      # that these calls can be chained.
+      #--
+      #: (Symbol name, _Field) -> self
+      def field(name, value)
+        raise ConfigurationError, "Cannot specify multiple #{name} fields" if @fields.key?(name)
+        @fields[name] = value
+        self
+      end
+    end
+
+    # Create a new repository for the given filepath.
+    #--
+    #: (String value) -> Repository
+    def self.filepath(value)
+      Repository.new(SourceFilepath.new(value))
+    end
+
+    # Create a new repository for the given string.
+    #--
+    #: (String value) -> Repository
+    def self.string(value)
+      Repository.new(SourceString.new(value))
+    end
+  end
+end
diff --git a/lib/prism/string_query.rb b/lib/prism/string_query.rb
new file mode 100644
index 0000000000..99ce57e5fe
--- /dev/null
+++ b/lib/prism/string_query.rb
@@ -0,0 +1,46 @@
+# frozen_string_literal: true
+# :markup: markdown
+#--
+# rbs_inline: enabled
+
+module Prism
+  # Query methods that allow categorizing strings based on their context for
+  # where they could be valid in a Ruby syntax tree.
+  class StringQuery
+    # @rbs!
+    #    def self.local?: (String string) -> bool
+    #    def self.constant?: (String string) -> bool
+    #    def self.method_name?: (String string) -> bool
+
+    # The string that this query is wrapping.
+    attr_reader :string #: String
+
+    # Initialize a new query with the given string.
+    #--
+    #: (String string) -> void
+    def initialize(string)
+      @string = string
+    end
+
+    # Whether or not this string is a valid local variable name.
+    #--
+    #: () -> bool
+    def local?
+      StringQuery.local?(string)
+    end
+
+    # Whether or not this string is a valid constant name.
+    #--
+    #: () -> bool
+    def constant?
+      StringQuery.constant?(string)
+    end
+
+    # Whether or not this string is a valid method name.
+    #--
+    #: () -> bool
+    def method_name?
+      StringQuery.method_name?(string)
+    end
+  end
+end
diff --git a/lib/prism/translation.rb b/lib/prism/translation.rb
new file mode 100644
index 0000000000..5a086a7542
--- /dev/null
+++ b/lib/prism/translation.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+# :markup: markdown
+#--
+# rbs_inline: enabled
+
+module Prism
+  # This module is responsible for converting the prism syntax tree into other
+  # syntax trees.
+  module Translation # steep:ignore
+    autoload :Parser, "prism/translation/parser"
+    autoload :ParserCurrent, "prism/translation/parser_current"
+    autoload :Parser33, "prism/translation/parser_versions"
+    autoload :Parser34, "prism/translation/parser_versions"
+    autoload :Parser35, "prism/translation/parser_versions"
+    autoload :Parser40, "prism/translation/parser_versions"
+    autoload :Parser41, "prism/translation/parser_versions"
+    autoload :Ripper, "prism/translation/ripper"
+    autoload :RubyParser, "prism/translation/ruby_parser"
+  end
+end
diff --git a/lib/prism/translation/parser.rb b/lib/prism/translation/parser.rb
new file mode 100644
index 0000000000..70031f133a
--- /dev/null
+++ b/lib/prism/translation/parser.rb
@@ -0,0 +1,376 @@
+# frozen_string_literal: true
+# :markup: markdown
+
+begin
+  required_version = ">= 3.3.7.2"
+  gem "parser", required_version
+  require "parser"
+rescue LoadError
+  warn(<<~MSG)
+    Error: Unable to load parser #{required_version}. \
+    Add `gem "parser"` to your Gemfile or run `bundle update parser`.
+  MSG
+  exit(1)
+end
+
+module Prism
+  module Translation
+    # This class is the entry-point for converting a prism syntax tree into the
+    # whitequark/parser gem's syntax tree. It inherits from the base parser for
+    # the parser gem, and overrides the parse* methods to parse with prism and
+    # then translate.
+    #
+    # Note that this version of the parser always parses using the latest
+    # version of Ruby syntax supported by Prism. If you want specific version
+    # support, use one of the version-specific subclasses, such as
+    # `Prism::Translation::Parser34`. If you want to parse using the same
+    # version of Ruby syntax as the currently running version of Ruby, use
+    # `Prism::Translation::ParserCurrent`.
+    class Parser < ::Parser::Base
+      Diagnostic = ::Parser::Diagnostic # :nodoc:
+      private_constant :Diagnostic
+
+      # The parser gem has a list of diagnostics with a hard-coded set of error
+      # messages. We create our own diagnostic class in order to set our own
+      # error messages.
+      class PrismDiagnostic < Diagnostic # :nodoc:
+        # This is the cached message coming from prism.
+        attr_reader :message
+
+        # Initialize a new diagnostic with the given message and location.
+        def initialize(message, level, reason, location)
+          @message = message
+          super(level, reason, {}, location, [])
+        end
+      end
+
+      Racc_debug_parser = false # :nodoc:
+
+      # The `builder` argument is used to create the parser using our custom builder class by default.
+      #
+      # By using the `:parser` keyword argument, you can translate in a way that is compatible with
+      # the Parser gem using any parser.
+      #
+      # For example, in RuboCop for Ruby LSP, the following approach can be used to improve performance
+      # by reusing a pre-parsed `Prism::ParseLexResult`:
+      #
+      #   class PrismPreparsed
+      #     def initialize(prism_result)
+      #       @prism_result = prism_result
+      #     end
+      #
+      #     def parse_lex(source, **options)
+      #       @prism_result
+      #     end
+      #   end
+      #
+      #   prism_preparsed = PrismPreparsed.new(prism_result)
+      #
+      #   Prism::Translation::Ruby34.new(builder, parser: prism_preparsed)
+      #
+      # In an object passed to the `:parser` keyword argument, the `parse` and `parse_lex` methods
+      # should be implemented as needed.
+      #
+      def initialize(builder = Prism::Translation::Parser::Builder.new, parser: Prism)
+        if !builder.is_a?(Prism::Translation::Parser::Builder)
+          warn(<<~MSG, uplevel: 1, category: :deprecated)
+            [deprecation]: The builder passed to `Prism::Translation::Parser.new` is not a \
+            `Prism::Translation::Parser::Builder` subclass. This will raise in the next major version.
+          MSG
+        end
+        @parser = parser
+
+        super(builder)
+      end
+
+      def version # :nodoc:
+        41
+      end
+
+      # The default encoding for Ruby files is UTF-8.
+      def default_encoding
+        Encoding::UTF_8
+      end
+
+      def yyerror # :nodoc:
+      end
+
+      # Parses a source buffer and returns the AST.
+      def parse(source_buffer)
+        @source_buffer = source_buffer
+        source = source_buffer.source
+
+        offset_cache = build_offset_cache(source)
+        result = unwrap(@parser.parse(source, **prism_options), offset_cache)
+
+        build_ast(result.value, offset_cache)
+      ensure
+        @source_buffer = nil
+      end
+
+      # Parses a source buffer and returns the AST and the source code comments.
+      def parse_with_comments(source_buffer)
+        @source_buffer = source_buffer
+        source = source_buffer.source
+
+        offset_cache = build_offset_cache(source)
+        result = unwrap(@parser.parse(source, **prism_options), offset_cache)
+
+        [
+          build_ast(result.value, offset_cache),
+          build_comments(result.comments, offset_cache)
+        ]
+      ensure
+        @source_buffer = nil
+      end
+
+      # Parses a source buffer and returns the AST, the source code comments,
+      # and the tokens emitted by the lexer.
+      def tokenize(source_buffer, recover = false)
+        @source_buffer = source_buffer
+        source = source_buffer.source
+
+        offset_cache = build_offset_cache(source)
+        result =
+          begin
+            unwrap(@parser.parse_lex(source, **prism_options), offset_cache)
+          rescue ::Parser::SyntaxError
+            raise if !recover
+          end
+
+        program, tokens = result.value
+        ast = build_ast(program, offset_cache) if result.success?
+
+        [
+          ast,
+          build_comments(result.comments, offset_cache),
+          build_tokens(tokens, offset_cache)
+        ]
+      ensure
+        @source_buffer = nil
+      end
+
+      # Since prism resolves num params for us, we don't need to support this
+      # kind of logic here.
+      def try_declare_numparam(node)
+        node.children[0].match?(/\A_[1-9]\z/)
+      end
+
+      private
+
+      # This is a hook to allow consumers to disable some errors if they don't
+      # want them to block creating the syntax tree.
+      def valid_error?(error)
+        true
+      end
+
+      # This is a hook to allow consumers to disable some warnings if they don't
+      # want them to block creating the syntax tree.
+      def valid_warning?(warning)
+        true
+      end
+
+      # Build a diagnostic from the given prism parse error.
+      def error_diagnostic(error, offset_cache)
+        location = error.location
+        diagnostic_location = build_range(location, offset_cache)
+
+        case error.type
+        when :argument_block_multi
+          Diagnostic.new(:error, :block_and_blockarg, {}, diagnostic_location, [])
+        when :argument_formal_constant
+          Diagnostic.new(:error, :argument_const, {}, diagnostic_location, [])
+        when :argument_formal_class
+          Diagnostic.new(:error, :argument_cvar, {}, diagnostic_location, [])
+        when :argument_formal_global
+          Diagnostic.new(:error, :argument_gvar, {}, diagnostic_location, [])
+        when :argument_formal_ivar
+          Diagnostic.new(:error, :argument_ivar, {}, diagnostic_location, [])
+        when :argument_no_forwarding_amp
+          Diagnostic.new(:error, :no_anonymous_blockarg, {}, diagnostic_location, [])
+        when :argument_no_forwarding_star
+          Diagnostic.new(:error, :no_anonymous_restarg, {}, diagnostic_location, [])
+        when :argument_no_forwarding_star_star
+          Diagnostic.new(:error, :no_anonymous_kwrestarg, {}, diagnostic_location, [])
+        when :begin_lonely_else
+          location = location.copy(length: 4)
+          diagnostic_location = build_range(location, offset_cache)
+          Diagnostic.new(:error, :useless_else, {}, diagnostic_location, [])
+        when :class_name, :module_name
+          Diagnostic.new(:error, :module_name_const, {}, diagnostic_location, [])
+        when :class_in_method
+          Diagnostic.new(:error, :class_in_def, {}, diagnostic_location, [])
+        when :def_endless_setter
+          Diagnostic.new(:error, :endless_setter, {}, diagnostic_location, [])
+        when :embdoc_term
+          Diagnostic.new(:error, :embedded_document, {}, diagnostic_location, [])
+        when :incomplete_variable_class, :incomplete_variable_class_3_3
+          location = location.copy(length: location.length + 1)
+          diagnostic_location = build_range(location, offset_cache)
+
+          Diagnostic.new(:error, :cvar_name, { name: location.slice }, diagnostic_location, [])
+        when :incomplete_variable_instance, :incomplete_variable_instance_3_3
+          location = location.copy(length: location.length + 1)
+          diagnostic_location = build_range(location, offset_cache)
+
+          Diagnostic.new(:error, :ivar_name, { name: location.slice }, diagnostic_location, [])
+        when :invalid_variable_global, :invalid_variable_global_3_3
+          Diagnostic.new(:error, :gvar_name, { name: location.slice }, diagnostic_location, [])
+        when :module_in_method
+          Diagnostic.new(:error, :module_in_def, {}, diagnostic_location, [])
+        when :numbered_parameter_ordinary
+          Diagnostic.new(:error, :ordinary_param_defined, {}, diagnostic_location, [])
+        when :numbered_parameter_outer_scope
+          Diagnostic.new(:error, :numparam_used_in_outer_scope, {}, diagnostic_location, [])
+        when :parameter_circular
+          Diagnostic.new(:error, :circular_argument_reference, { var_name: location.slice }, diagnostic_location, [])
+        when :parameter_name_repeat
+          Diagnostic.new(:error, :duplicate_argument, {}, diagnostic_location, [])
+        when :parameter_numbered_reserved
+          Diagnostic.new(:error, :reserved_for_numparam, { name: location.slice }, diagnostic_location, [])
+        when :regexp_unknown_options
+          Diagnostic.new(:error, :regexp_options, { options: location.slice[1..] }, diagnostic_location, [])
+        when :singleton_for_literals
+          Diagnostic.new(:error, :singleton_literal, {}, diagnostic_location, [])
+        when :string_literal_eof
+          Diagnostic.new(:error, :string_eof, {}, diagnostic_location, [])
+        when :unexpected_token_ignore
+          Diagnostic.new(:error, :unexpected_token, { token: location.slice }, diagnostic_location, [])
+        when :write_target_in_method
+          Diagnostic.new(:error, :dynamic_const, {}, diagnostic_location, [])
+        else
+          PrismDiagnostic.new(error.message, :error, error.type, diagnostic_location)
+        end
+      end
+
+      # Build a diagnostic from the given prism parse warning.
+      def warning_diagnostic(warning, offset_cache)
+        diagnostic_location = build_range(warning.location, offset_cache)
+
+        case warning.type
+        when :ambiguous_first_argument_plus
+          Diagnostic.new(:warning, :ambiguous_prefix, { prefix: "+" }, diagnostic_location, [])
+        when :ambiguous_first_argument_minus
+          Diagnostic.new(:warning, :ambiguous_prefix, { prefix: "-" }, diagnostic_location, [])
+        when :ambiguous_prefix_ampersand
+          Diagnostic.new(:warning, :ambiguous_prefix, { prefix: "&" }, diagnostic_location, [])
+        when :ambiguous_prefix_star
+          Diagnostic.new(:warning, :ambiguous_prefix, { prefix: "*" }, diagnostic_location, [])
+        when :ambiguous_prefix_star_star
+          Diagnostic.new(:warning, :ambiguous_prefix, { prefix: "**" }, diagnostic_location, [])
+        when :ambiguous_slash
+          Diagnostic.new(:warning, :ambiguous_regexp, {}, diagnostic_location, [])
+        when :dot_dot_dot_eol
+          Diagnostic.new(:warning, :triple_dot_at_eol, {}, diagnostic_location, [])
+        when :duplicated_hash_key
+          # skip, parser does this on its own
+        else
+          PrismDiagnostic.new(warning.message, :warning, warning.type, diagnostic_location)
+        end
+      end
+
+      # If there was a error generated during the parse, then raise an
+      # appropriate syntax error. Otherwise return the result.
+      def unwrap(result, offset_cache)
+        result.errors.each do |error|
+          next unless valid_error?(error)
+          diagnostics.process(error_diagnostic(error, offset_cache))
+        end
+
+        result.warnings.each do |warning|
+          next unless valid_warning?(warning)
+          diagnostic = warning_diagnostic(warning, offset_cache)
+          diagnostics.process(diagnostic) if diagnostic
+        end
+
+        result
+      end
+
+      # Prism deals with offsets in bytes, while the parser gem deals with
+      # offsets in characters. We need to handle this conversion in order to
+      # build the parser gem AST.
+      #
+      # If the bytesize of the source is the same as the length, then we can
+      # just use the offset directly. Otherwise, we build an array where the
+      # index is the byte offset and the value is the character offset.
+      def build_offset_cache(source)
+        if source.bytesize == source.length
+          -> (offset) { offset }
+        else
+          offset_cache = []
+          offset = 0
+
+          source.each_char do |char|
+            char.bytesize.times { offset_cache << offset }
+            offset += 1
+          end
+
+          offset_cache << offset
+        end
+      end
+
+      # Build the parser gem AST from the prism AST.
+      def build_ast(program, offset_cache)
+        program.accept(Compiler.new(self, offset_cache))
+      end
+
+      # Build the parser gem comments from the prism comments.
+      def build_comments(comments, offset_cache)
+        comments.map do |comment|
+          ::Parser::Source::Comment.new(build_range(comment.location, offset_cache))
+        end
+      end
+
+      # Build the parser gem tokens from the prism tokens.
+      def build_tokens(tokens, offset_cache)
+        Lexer.new(source_buffer, tokens, offset_cache).to_a
+      end
+
+      # Build a range from a prism location.
+      def build_range(location, offset_cache)
+        ::Parser::Source::Range.new(
+          source_buffer,
+          offset_cache[location.start_offset],
+          offset_cache[location.end_offset]
+        )
+      end
+
+      # Options for how prism should parse/lex the source.
+      def prism_options
+        options = {
+          filepath: @source_buffer.name,
+          version: convert_for_prism(version),
+          partial_script: true,
+        }
+        # The parser gem always encodes to UTF-8, unless it is binary.
+        # https://github.com/whitequark/parser/blob/v3.3.6.0/lib/parser/source/buffer.rb#L80-L107
+        options[:encoding] = false if @source_buffer.source.encoding != Encoding::BINARY
+
+        options
+      end
+
+      # Converts the version format handled by Parser to the format handled by Prism.
+      def convert_for_prism(version)
+        case version
+        when 33
+          "3.3.1"
+        when 34
+          "3.4.0"
+        when 35, 40
+          "4.0.0"
+        when 41
+          "4.1.0"
+        else
+          "latest"
+        end
+      end
+
+      require_relative "parser/builder"
+      require_relative "parser/compiler"
+      require_relative "parser/lexer"
+
+      private_constant :Compiler
+      private_constant :Lexer
+    end
+  end
+end
diff --git a/lib/prism/translation/parser/builder.rb b/lib/prism/translation/parser/builder.rb
new file mode 100644
index 0000000000..7fc3bba6b7
--- /dev/null
+++ b/lib/prism/translation/parser/builder.rb
@@ -0,0 +1,70 @@
+# frozen_string_literal: true
+# :markup: markdown
+
+module Prism
+  module Translation
+    class Parser
+      # A builder that knows how to convert more modern Ruby syntax
+      # into whitequark/parser gem's syntax tree.
+      class Builder < ::Parser::Builders::Default
+        # It represents the `it` block argument, which is not yet implemented in
+        # the Parser gem.
+        def itarg
+          n(:itarg, [:it], nil)
+        end
+
+        # The following three lines have been added to support the `it` block
+        # parameter syntax in the source code below.
+        #
+        #   if args.type == :itarg
+        #     block_type = :itblock
+        #     args = :it
+        #
+        # https://github.com/whitequark/parser/blob/v3.3.7.1/lib/parser/builders/default.rb#L1122-L1155
+        def block(method_call, begin_t, args, body, end_t)
+          _receiver, _selector, *call_args = *method_call
+
+          if method_call.type == :yield
+            diagnostic :error, :block_given_to_yield, nil, method_call.loc.keyword, [loc(begin_t)]
+          end
+
+          last_arg = call_args.last
+          if last_arg && (last_arg.type == :block_pass || last_arg.type == :forwarded_args)
+            diagnostic :error, :block_and_blockarg, nil, last_arg.loc.expression, [loc(begin_t)]
+          end
+
+          if args.type == :itarg
+            block_type = :itblock
+            args = :it
+          elsif args.type == :numargs
+            block_type = :numblock
+            args = args.children[0]
+          else
+            block_type = :block
+          end
+
+          if [:send, :csend, :index, :super, :zsuper, :lambda].include?(method_call.type)
+            n(block_type, [ method_call, args, body ],
+              block_map(method_call.loc.expression, begin_t, end_t))
+          else
+            # Code like "return foo 1 do end" is reduced in a weird sequence.
+            # Here, method_call is actually (return).
+            actual_send, = *method_call
+            block =
+              n(block_type, [ actual_send, args, body ],
+                block_map(actual_send.loc.expression, begin_t, end_t))
+
+            n(method_call.type, [ block ],
+              method_call.loc.with_expression(join_exprs(method_call, block)))
+          end
+        end
+
+        # def foo(&nil); end
+        #         ^^^^
+        def blocknilarg(amper_t, nil_t)
+          n0(:blocknilarg, arg_prefix_map(amper_t, nil_t))
+        end
+      end
+    end
+  end
+end
diff --git a/lib/prism/translation/parser/compiler.rb b/lib/prism/translation/parser/compiler.rb
new file mode 100644
index 0000000000..d11db12ae6
--- /dev/null
+++ b/lib/prism/translation/parser/compiler.rb
@@ -0,0 +1,2219 @@
+# frozen_string_literal: true
+# :markup: markdown
+
+module Prism
+  module Translation
+    class Parser
+      # A visitor that knows how to convert a prism syntax tree into the
+      # whitequark/parser gem's syntax tree.
+      class Compiler < ::Prism::Compiler # :nodoc:
+        # Raised when the tree is malformed or there is a bug in the compiler.
+        class CompilationError < StandardError # :nodoc:
+        end
+
+        # The Parser::Base instance that is being used to build the AST.
+        attr_reader :parser
+
+        # The Parser::Builders::Default instance that is being used to build the
+        # AST.
+        attr_reader :builder
+
+        # The Parser::Source::Buffer instance that is holding a reference to the
+        # source code.
+        attr_reader :source_buffer
+
+        # The offset cache that is used to map between byte and character
+        # offsets in the file.
+        attr_reader :offset_cache
+
+        # The types of values that can be forwarded in the current scope.
+        attr_reader :forwarding
+
+        # Whether or not the current node is in a destructure.
+        attr_reader :in_destructure
+
+        # Whether or not the current node is in a pattern.
+        attr_reader :in_pattern
+
+        # Initialize a new compiler with the given parser, offset cache, and
+        # options.
+        def initialize(parser, offset_cache, forwarding: [], in_destructure: false, in_pattern: false)
+          @parser = parser
+          @builder = parser.builder
+          @source_buffer = parser.source_buffer
+          @offset_cache = offset_cache
+
+          @forwarding = forwarding
+          @in_destructure = in_destructure
+          @in_pattern = in_pattern
+        end
+
+        # alias foo bar
+        # ^^^^^^^^^^^^^
+        def visit_alias_method_node(node)
+          builder.alias(token(node.keyword_loc), visit(node.new_name), visit(node.old_name))
+        end
+
+        # alias $foo $bar
+        # ^^^^^^^^^^^^^^^
+        def visit_alias_global_variable_node(node)
+          builder.alias(token(node.keyword_loc), visit(node.new_name), visit(node.old_name))
+        end
+
+        # foo => bar | baz
+        #        ^^^^^^^^^
+        def visit_alternation_pattern_node(node)
+          builder.match_alt(visit(node.left), token(node.operator_loc), visit(node.right))
+        end
+
+        # a and b
+        # ^^^^^^^
+        def visit_and_node(node)
+          builder.logical_op(:and, visit(node.left), token(node.operator_loc), visit(node.right))
+        end
+
+        # []
+        # ^^
+        def visit_array_node(node)
+          if node.opening&.start_with?("%w", "%W", "%i", "%I")
+            elements = node.elements.flat_map do |element|
+              if element.is_a?(StringNode)
+                if element.content.include?("\n")
+                  string_nodes_from_line_continuations(element.unescaped, element.content, element.content_loc.start_offset, node.opening)
+                else
+                  [builder.string_internal([element.unescaped, srange(element.content_loc)])]
+                end
+              elsif element.is_a?(InterpolatedStringNode)
+                builder.string_compose(
+                  token(element.opening_loc),
+                  string_nodes_from_interpolation(element, node.opening),
+                  token(element.closing_loc)
+                )
+              else
+                [visit(element)]
+              end
+            end
+          else
+            elements = visit_all(node.elements)
+          end
+
+          builder.array(token(node.opening_loc), elements, token(node.closing_loc))
+        end
+
+        # foo => [bar]
+        #        ^^^^^
+        def visit_array_pattern_node(node)
+          elements = [*node.requireds]
+          elements << node.rest if !node.rest.nil? && !node.rest.is_a?(ImplicitRestNode)
+          elements.concat(node.posts)
+          visited = visit_all(elements)
+
+          if node.rest.is_a?(ImplicitRestNode)
+            visited[-1] = builder.match_with_trailing_comma(visited[-1], token(node.rest.location))
+          end
+
+          if node.constant
+            if visited.empty?
+              builder.const_pattern(visit(node.constant), token(node.opening_loc), builder.array_pattern(token(node.opening_loc), visited, token(node.closing_loc)), token(node.closing_loc))
+            else
+              builder.const_pattern(visit(node.constant), token(node.opening_loc), builder.array_pattern(nil, visited, nil), token(node.closing_loc))
+            end
+          else
+            builder.array_pattern(token(node.opening_loc), visited, token(node.closing_loc))
+          end
+        end
+
+        # foo(bar)
+        #     ^^^
+        def visit_arguments_node(node)
+          visit_all(node.arguments)
+        end
+
+        # { a: 1 }
+        #   ^^^^
+        def visit_assoc_node(node)
+          key = node.key
+
+          if  node.value.is_a?(ImplicitNode)
+            if in_pattern
+              if key.is_a?(SymbolNode)
+                if key.opening.nil?
+                  builder.match_hash_var([key.unescaped, srange(key.location)])
+                else
+                  builder.match_hash_var_from_str(token(key.opening_loc), [builder.string_internal([key.unescaped, srange(key.value_loc)])], token(key.closing_loc))
+                end
+              else
+                builder.match_hash_var_from_str(token(key.opening_loc), visit_all(key.parts), token(key.closing_loc))
+              end
+            else
+              value = node.value.value
+
+              implicit_value = if value.is_a?(CallNode)
+                builder.call_method(nil, nil, [value.name, srange(value.message_loc)])
+              elsif value.is_a?(ConstantReadNode)
+                builder.const([value.name, srange(key.value_loc)])
+              else
+                builder.ident([value.name, srange(key.value_loc)]).updated(:lvar)
+              end
+
+              builder.pair_keyword([key.unescaped, srange(key)], implicit_value)
+            end
+          elsif node.operator_loc
+            builder.pair(visit(key), token(node.operator_loc), visit(node.value))
+          elsif key.is_a?(SymbolNode) && key.opening_loc.nil?
+            builder.pair_keyword([key.unescaped, srange(key.location)], visit(node.value))
+          else
+            parts =
+              if key.is_a?(SymbolNode)
+                [builder.string_internal([key.unescaped, srange(key.value_loc)])]
+              else
+                visit_all(key.parts)
+              end
+
+            builder.pair_quoted(token(key.opening_loc), parts, token(key.closing_loc), visit(node.value))
+          end
+        end
+
+        # def foo(**); bar(**); end
+        #                  ^^
+        #
+        # { **foo }
+        #   ^^^^^
+        def visit_assoc_splat_node(node)
+          if in_pattern
+            builder.match_rest(token(node.operator_loc), token(node.value&.location))
+          elsif node.value.nil? && forwarding.include?(:**)
+            builder.forwarded_kwrestarg(token(node.operator_loc))
+          else
+            builder.kwsplat(token(node.operator_loc), visit(node.value))
+          end
+        end
+
+        # $+
+        # ^^
+        def visit_back_reference_read_node(node)
+          builder.back_ref(token(node.location))
+        end
+
+        # begin end
+        # ^^^^^^^^^
+        def visit_begin_node(node)
+          rescue_bodies = []
+
+          if (rescue_clause = node.rescue_clause)
+            begin
+              find_start_offset = (rescue_clause.reference&.location || rescue_clause.exceptions.last&.location || rescue_clause.keyword_loc).end_offset
+              find_end_offset = (
+                rescue_clause.statements&.location&.start_offset ||
+                rescue_clause.subsequent&.location&.start_offset ||
+                node.else_clause&.location&.start_offset ||
+                node.ensure_clause&.location&.start_offset ||
+                node.end_keyword_loc&.start_offset ||
+                find_start_offset + 1
+              )
+
+              rescue_bodies << builder.rescue_body(
+                token(rescue_clause.keyword_loc),
+                rescue_clause.exceptions.any? ? builder.array(nil, visit_all(rescue_clause.exceptions), nil) : nil,
+                token(rescue_clause.operator_loc),
+                visit(rescue_clause.reference),
+                srange_semicolon(find_start_offset, find_end_offset),
+                visit(rescue_clause.statements)
+              )
+            end until (rescue_clause = rescue_clause.subsequent).nil?
+          end
+
+          begin_body =
+            builder.begin_body(
+              visit(node.statements),
+              rescue_bodies,
+              token(node.else_clause&.else_keyword_loc),
+              visit(node.else_clause),
+              token(node.ensure_clause&.ensure_keyword_loc),
+              visit(node.ensure_clause&.statements)
+            )
+
+          if node.begin_keyword_loc
+            builder.begin_keyword(token(node.begin_keyword_loc), begin_body, token(node.end_keyword_loc))
+          else
+            begin_body
+          end
+        end
+
+        # foo(&bar)
+        #     ^^^^
+        def visit_block_argument_node(node)
+          builder.block_pass(token(node.operator_loc), visit(node.expression))
+        end
+
+        # foo { |; bar| }
+        #          ^^^
+        def visit_block_local_variable_node(node)
+          builder.shadowarg(token(node.location))
+        end
+
+        # A block on a keyword or method call.
+        def visit_block_node(node)
+          raise CompilationError, "Cannot directly compile block nodes"
+        end
+
+        # def foo(&bar); end
+        #         ^^^^
+        def visit_block_parameter_node(node)
+          builder.blockarg(token(node.operator_loc), token(node.name_loc))
+        end
+
+        # A block's parameters.
+        def visit_block_parameters_node(node)
+          [*visit(node.parameters)].concat(visit_all(node.locals))
+        end
+
+        # break
+        # ^^^^^
+        #
+        # break foo
+        # ^^^^^^^^^
+        def visit_break_node(node)
+          builder.keyword_cmd(:break, token(node.keyword_loc), nil, visit(node.arguments) || [], nil)
+        end
+
+        # foo
+        # ^^^
+        #
+        # foo.bar
+        # ^^^^^^^
+        #
+        # foo.bar() {}
+        # ^^^^^^^^^^^^
+        def visit_call_node(node)
+          name = node.name
+          arguments = node.arguments&.arguments || []
+          block = node.block
+
+          if block.is_a?(BlockArgumentNode)
+            arguments = [*arguments, block]
+            block = nil
+          end
+
+          if node.call_operator_loc.nil?
+            case name
+            when :!
+              return visit_block(builder.not_op(token(node.message_loc), token(node.opening_loc), visit(node.receiver), token(node.closing_loc)), block)
+            when :=~
+              if (receiver = node.receiver).is_a?(RegularExpressionNode)
+                return builder.match_op(visit(receiver), token(node.message_loc), visit(node.arguments.arguments.first))
+              end
+            when :[]
+              return visit_block(builder.index(visit(node.receiver), token(node.opening_loc), visit_all(arguments), token(node.closing_loc)), block)
+            when :[]=
+              if node.message != "[]=" && node.arguments && block.nil? && !node.safe_navigation?
+                arguments = node.arguments.arguments[...-1]
+                arguments << node.block if node.block
+
+                return visit_block(
+                  builder.assign(
+                    builder.index_asgn(
+                      visit(node.receiver),
+                      token(node.opening_loc),
+                      visit_all(arguments),
+                      token(node.closing_loc),
+                    ),
+                    token(node.equal_loc),
+                    visit(node.arguments.arguments.last)
+                  ),
+                  block
+                )
+              end
+            end
+          end
+
+          message_loc = node.message_loc
+          call_operator_loc = node.call_operator_loc
+          call_operator = [{ "." => :dot, "&." => :anddot, "::" => "::" }.fetch(call_operator_loc.slice), srange(call_operator_loc)] if call_operator_loc
+
+          visit_block(
+            if name.end_with?("=") && !message_loc.slice.end_with?("=") && node.arguments && block.nil?
+              builder.assign(
+                builder.attr_asgn(visit(node.receiver), call_operator, token(message_loc)),
+                token(node.equal_loc),
+                visit(node.arguments.arguments.last)
+              )
+            else
+              builder.call_method(
+                visit(node.receiver),
+                call_operator,
+                message_loc ? [node.name, srange(message_loc)] : nil,
+                token(node.opening_loc),
+                visit_all(arguments),
+                token(node.closing_loc)
+              )
+            end,
+            block
+          )
+        end
+
+        # foo.bar += baz
+        # ^^^^^^^^^^^^^^^
+        def visit_call_operator_write_node(node)
+          call_operator_loc = node.call_operator_loc
+
+          builder.op_assign(
+            builder.call_method(
+              visit(node.receiver),
+              call_operator_loc.nil? ? nil : [{ "." => :dot, "&." => :anddot, "::" => "::" }.fetch(call_operator_loc.slice), srange(call_operator_loc)],
+              node.message_loc ? [node.read_name, srange(node.message_loc)] : nil,
+              nil,
+              [],
+              nil
+            ),
+            [node.binary_operator_loc.slice.chomp("="), srange(node.binary_operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # foo.bar &&= baz
+        # ^^^^^^^^^^^^^^^
+        def visit_call_and_write_node(node)
+          call_operator_loc = node.call_operator_loc
+
+          builder.op_assign(
+            builder.call_method(
+              visit(node.receiver),
+              call_operator_loc.nil? ? nil : [{ "." => :dot, "&." => :anddot, "::" => "::" }.fetch(call_operator_loc.slice), srange(call_operator_loc)],
+              node.message_loc ? [node.read_name, srange(node.message_loc)] : nil,
+              nil,
+              [],
+              nil
+            ),
+            [node.operator_loc.slice.chomp("="), srange(node.operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # foo.bar ||= baz
+        # ^^^^^^^^^^^^^^^
+        def visit_call_or_write_node(node)
+          call_operator_loc = node.call_operator_loc
+
+          builder.op_assign(
+            builder.call_method(
+              visit(node.receiver),
+              call_operator_loc.nil? ? nil : [{ "." => :dot, "&." => :anddot, "::" => "::" }.fetch(call_operator_loc.slice), srange(call_operator_loc)],
+              node.message_loc ? [node.read_name, srange(node.message_loc)] : nil,
+              nil,
+              [],
+              nil
+            ),
+            [node.operator_loc.slice.chomp("="), srange(node.operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # foo.bar, = 1
+        # ^^^^^^^
+        def visit_call_target_node(node)
+          call_operator_loc = node.call_operator_loc
+
+          builder.attr_asgn(
+            visit(node.receiver),
+            call_operator_loc.nil? ? nil : [{ "." => :dot, "&." => :anddot, "::" => "::" }.fetch(call_operator_loc.slice), srange(call_operator_loc)],
+            token(node.message_loc)
+          )
+        end
+
+        # foo => bar => baz
+        #        ^^^^^^^^^^
+        def visit_capture_pattern_node(node)
+          builder.match_as(visit(node.value), token(node.operator_loc), visit(node.target))
+        end
+
+        # case foo; when bar; end
+        # ^^^^^^^^^^^^^^^^^^^^^^^
+        def visit_case_node(node)
+          builder.case(
+            token(node.case_keyword_loc),
+            visit(node.predicate),
+            visit_all(node.conditions),
+            token(node.else_clause&.else_keyword_loc),
+            visit(node.else_clause),
+            token(node.end_keyword_loc)
+          )
+        end
+
+        # case foo; in bar; end
+        # ^^^^^^^^^^^^^^^^^^^^^
+        def visit_case_match_node(node)
+          builder.case_match(
+            token(node.case_keyword_loc),
+            visit(node.predicate),
+            visit_all(node.conditions),
+            token(node.else_clause&.else_keyword_loc),
+            visit(node.else_clause),
+            token(node.end_keyword_loc)
+          )
+        end
+
+        # class Foo; end
+        # ^^^^^^^^^^^^^^
+        def visit_class_node(node)
+          builder.def_class(
+            token(node.class_keyword_loc),
+            visit(node.constant_path),
+            token(node.inheritance_operator_loc),
+            visit(node.superclass),
+            node.body&.accept(copy_compiler(forwarding: [])),
+            token(node.end_keyword_loc)
+          )
+        end
+
+        # @@foo
+        # ^^^^^
+        def visit_class_variable_read_node(node)
+          builder.cvar(token(node.location))
+        end
+
+        # @@foo = 1
+        # ^^^^^^^^^
+        def visit_class_variable_write_node(node)
+          builder.assign(
+            builder.assignable(builder.cvar(token(node.name_loc))),
+            token(node.operator_loc),
+            visit(node.value)
+          )
+        end
+
+        # @@foo += bar
+        # ^^^^^^^^^^^^
+        def visit_class_variable_operator_write_node(node)
+          builder.op_assign(
+            builder.assignable(builder.cvar(token(node.name_loc))),
+            [node.binary_operator_loc.slice.chomp("="), srange(node.binary_operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # @@foo &&= bar
+        # ^^^^^^^^^^^^^
+        def visit_class_variable_and_write_node(node)
+          builder.op_assign(
+            builder.assignable(builder.cvar(token(node.name_loc))),
+            [node.operator_loc.slice.chomp("="), srange(node.operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # @@foo ||= bar
+        # ^^^^^^^^^^^^^
+        def visit_class_variable_or_write_node(node)
+          builder.op_assign(
+            builder.assignable(builder.cvar(token(node.name_loc))),
+            [node.operator_loc.slice.chomp("="), srange(node.operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # @@foo, = bar
+        # ^^^^^
+        def visit_class_variable_target_node(node)
+          builder.assignable(builder.cvar(token(node.location)))
+        end
+
+        # Foo
+        # ^^^
+        def visit_constant_read_node(node)
+          builder.const([node.name, srange(node.location)])
+        end
+
+        # Foo = 1
+        # ^^^^^^^
+        #
+        # Foo, Bar = 1
+        # ^^^  ^^^
+        def visit_constant_write_node(node)
+          builder.assign(builder.assignable(builder.const([node.name, srange(node.name_loc)])), token(node.operator_loc), visit(node.value))
+        end
+
+        # Foo += bar
+        # ^^^^^^^^^^^
+        def visit_constant_operator_write_node(node)
+          builder.op_assign(
+            builder.assignable(builder.const([node.name, srange(node.name_loc)])),
+            [node.binary_operator_loc.slice.chomp("="), srange(node.binary_operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # Foo &&= bar
+        # ^^^^^^^^^^^^
+        def visit_constant_and_write_node(node)
+          builder.op_assign(
+            builder.assignable(builder.const([node.name, srange(node.name_loc)])),
+            [node.operator_loc.slice.chomp("="), srange(node.operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # Foo ||= bar
+        # ^^^^^^^^^^^^
+        def visit_constant_or_write_node(node)
+          builder.op_assign(
+            builder.assignable(builder.const([node.name, srange(node.name_loc)])),
+            [node.operator_loc.slice.chomp("="), srange(node.operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # Foo, = bar
+        # ^^^
+        def visit_constant_target_node(node)
+          builder.assignable(builder.const([node.name, srange(node.location)]))
+        end
+
+        # Foo::Bar
+        # ^^^^^^^^
+        def visit_constant_path_node(node)
+          if node.parent.nil?
+            builder.const_global(
+              token(node.delimiter_loc),
+              [node.name, srange(node.name_loc)]
+            )
+          else
+            builder.const_fetch(
+              visit(node.parent),
+              token(node.delimiter_loc),
+              [node.name, srange(node.name_loc)]
+            )
+          end
+        end
+
+        # Foo::Bar = 1
+        # ^^^^^^^^^^^^
+        #
+        # Foo::Foo, Bar::Bar = 1
+        # ^^^^^^^^  ^^^^^^^^
+        def visit_constant_path_write_node(node)
+          builder.assign(
+            builder.assignable(visit(node.target)),
+            token(node.operator_loc),
+            visit(node.value)
+          )
+        end
+
+        # Foo::Bar += baz
+        # ^^^^^^^^^^^^^^^
+        def visit_constant_path_operator_write_node(node)
+          builder.op_assign(
+            builder.assignable(visit(node.target)),
+            [node.binary_operator_loc.slice.chomp("="), srange(node.binary_operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # Foo::Bar &&= baz
+        # ^^^^^^^^^^^^^^^^
+        def visit_constant_path_and_write_node(node)
+          builder.op_assign(
+            builder.assignable(visit(node.target)),
+            [node.operator_loc.slice.chomp("="), srange(node.operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # Foo::Bar ||= baz
+        # ^^^^^^^^^^^^^^^^
+        def visit_constant_path_or_write_node(node)
+          builder.op_assign(
+            builder.assignable(visit(node.target)),
+            [node.operator_loc.slice.chomp("="), srange(node.operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # Foo::Bar, = baz
+        # ^^^^^^^^
+        def visit_constant_path_target_node(node)
+          builder.assignable(visit_constant_path_node(node))
+        end
+
+        # def foo; end
+        # ^^^^^^^^^^^^
+        #
+        # def self.foo; end
+        # ^^^^^^^^^^^^^^^^^
+        def visit_def_node(node)
+          if node.equal_loc
+            if node.receiver
+              builder.def_endless_singleton(
+                token(node.def_keyword_loc),
+                visit(node.receiver.is_a?(ParenthesesNode) ? node.receiver.body : node.receiver),
+                token(node.operator_loc),
+                token(node.name_loc),
+                builder.args(token(node.lparen_loc), visit(node.parameters) || [], token(node.rparen_loc), false),
+                token(node.equal_loc),
+                node.body&.accept(copy_compiler(forwarding: find_forwarding(node.parameters)))
+              )
+            else
+              builder.def_endless_method(
+                token(node.def_keyword_loc),
+                token(node.name_loc),
+                builder.args(token(node.lparen_loc), visit(node.parameters) || [], token(node.rparen_loc), false),
+                token(node.equal_loc),
+                node.body&.accept(copy_compiler(forwarding: find_forwarding(node.parameters)))
+              )
+            end
+          elsif node.receiver
+            builder.def_singleton(
+              token(node.def_keyword_loc),
+              visit(node.receiver.is_a?(ParenthesesNode) ? node.receiver.body : node.receiver),
+              token(node.operator_loc),
+              token(node.name_loc),
+              builder.args(token(node.lparen_loc), visit(node.parameters) || [], token(node.rparen_loc), false),
+              node.body&.accept(copy_compiler(forwarding: find_forwarding(node.parameters))),
+              token(node.end_keyword_loc)
+            )
+          else
+            builder.def_method(
+              token(node.def_keyword_loc),
+              token(node.name_loc),
+              builder.args(token(node.lparen_loc), visit(node.parameters) || [], token(node.rparen_loc), false),
+              node.body&.accept(copy_compiler(forwarding: find_forwarding(node.parameters))),
+              token(node.end_keyword_loc)
+            )
+          end
+        end
+
+        # defined? a
+        # ^^^^^^^^^^
+        #
+        # defined?(a)
+        # ^^^^^^^^^^^
+        def visit_defined_node(node)
+          # Very weird circumstances here where something like:
+          #
+          #     defined?
+          #     (1)
+          #
+          # gets parsed in Ruby as having only the `1` expression but in parser
+          # it gets parsed as having a begin. In this case we need to synthesize
+          # that begin to match parser's behavior.
+          if node.lparen_loc && node.keyword_loc.join(node.lparen_loc).slice.include?("\n")
+            builder.keyword_cmd(
+              :defined?,
+              token(node.keyword_loc),
+              nil,
+              [
+                builder.begin(
+                  token(node.lparen_loc),
+                  visit(node.value),
+                  token(node.rparen_loc)
+                )
+              ],
+              nil
+            )
+          else
+            builder.keyword_cmd(
+              :defined?,
+              token(node.keyword_loc),
+              token(node.lparen_loc),
+              [visit(node.value)],
+              token(node.rparen_loc)
+            )
+          end
+        end
+
+        # if foo then bar else baz end
+        #                 ^^^^^^^^^^^^
+        def visit_else_node(node)
+          visit(node.statements)
+        end
+
+        # "foo #{bar}"
+        #      ^^^^^^
+        def visit_embedded_statements_node(node)
+          builder.begin(
+            token(node.opening_loc),
+            visit(node.statements),
+            token(node.closing_loc)
+          )
+        end
+
+        # "foo #@bar"
+        #      ^^^^^
+        def visit_embedded_variable_node(node)
+          visit(node.variable)
+        end
+
+        # begin; foo; ensure; bar; end
+        #             ^^^^^^^^^^^^
+        def visit_ensure_node(node)
+          raise CompilationError, "Cannot directly compile ensure nodes"
+        end
+
+        # false
+        # ^^^^^
+        def visit_false_node(node)
+          builder.false(token(node.location))
+        end
+
+        # foo => [*, bar, *]
+        #        ^^^^^^^^^^^
+        def visit_find_pattern_node(node)
+          elements = [node.left, *node.requireds, node.right]
+
+          if node.constant
+            builder.const_pattern(visit(node.constant), token(node.opening_loc), builder.find_pattern(nil, visit_all(elements), nil), token(node.closing_loc))
+          else
+            builder.find_pattern(token(node.opening_loc), visit_all(elements), token(node.closing_loc))
+          end
+        end
+
+        # 1.0
+        # ^^^
+        def visit_float_node(node)
+          visit_numeric(node, builder.float([node.value, srange(node.location)]))
+        end
+
+        # for foo in bar do end
+        # ^^^^^^^^^^^^^^^^^^^^^
+        def visit_for_node(node)
+          builder.for(
+            token(node.for_keyword_loc),
+            visit(node.index),
+            token(node.in_keyword_loc),
+            visit(node.collection),
+            if (do_keyword_loc = node.do_keyword_loc)
+              token(do_keyword_loc)
+            else
+              srange_semicolon(node.collection.location.end_offset, (node.statements&.location || node.end_keyword_loc).start_offset)
+            end,
+            visit(node.statements),
+            token(node.end_keyword_loc)
+          )
+        end
+
+        # def foo(...); bar(...); end
+        #                   ^^^
+        def visit_forwarding_arguments_node(node)
+          builder.forwarded_args(token(node.location))
+        end
+
+        # def foo(...); end
+        #         ^^^
+        def visit_forwarding_parameter_node(node)
+          builder.forward_arg(token(node.location))
+        end
+
+        # super
+        # ^^^^^
+        #
+        # super {}
+        # ^^^^^^^^
+        def visit_forwarding_super_node(node)
+          visit_block(
+            builder.keyword_cmd(
+              :zsuper,
+              ["super", srange_offsets(node.location.start_offset, node.location.start_offset + 5)]
+            ),
+            node.block
+          )
+        end
+
+        # $foo
+        # ^^^^
+        def visit_global_variable_read_node(node)
+          builder.gvar(token(node.location))
+        end
+
+        # $foo = 1
+        # ^^^^^^^^
+        def visit_global_variable_write_node(node)
+          builder.assign(
+            builder.assignable(builder.gvar(token(node.name_loc))),
+            token(node.operator_loc),
+            visit(node.value)
+          )
+        end
+
+        # $foo += bar
+        # ^^^^^^^^^^^
+        def visit_global_variable_operator_write_node(node)
+          builder.op_assign(
+            builder.assignable(builder.gvar(token(node.name_loc))),
+            [node.binary_operator_loc.slice.chomp("="), srange(node.binary_operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # $foo &&= bar
+        # ^^^^^^^^^^^^
+        def visit_global_variable_and_write_node(node)
+          builder.op_assign(
+            builder.assignable(builder.gvar(token(node.name_loc))),
+            [node.operator_loc.slice.chomp("="), srange(node.operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # $foo ||= bar
+        # ^^^^^^^^^^^^
+        def visit_global_variable_or_write_node(node)
+          builder.op_assign(
+            builder.assignable(builder.gvar(token(node.name_loc))),
+            [node.operator_loc.slice.chomp("="), srange(node.operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # $foo, = bar
+        # ^^^^
+        def visit_global_variable_target_node(node)
+          builder.assignable(builder.gvar([node.slice, srange(node.location)]))
+        end
+
+        # {}
+        # ^^
+        def visit_hash_node(node)
+          builder.associate(
+            token(node.opening_loc),
+            visit_all(node.elements),
+            token(node.closing_loc)
+          )
+        end
+
+        # foo => {}
+        #        ^^
+        def visit_hash_pattern_node(node)
+          elements = [*node.elements, *node.rest]
+
+          if node.constant
+            builder.const_pattern(visit(node.constant), token(node.opening_loc), builder.hash_pattern(nil, visit_all(elements), nil), token(node.closing_loc))
+          else
+            builder.hash_pattern(token(node.opening_loc), visit_all(elements), token(node.closing_loc))
+          end
+        end
+
+        # if foo then bar end
+        # ^^^^^^^^^^^^^^^^^^^
+        #
+        # bar if foo
+        # ^^^^^^^^^^
+        #
+        # foo ? bar : baz
+        # ^^^^^^^^^^^^^^^
+        def visit_if_node(node)
+          if !node.if_keyword_loc
+            builder.ternary(
+              visit(node.predicate),
+              token(node.then_keyword_loc),
+              visit(node.statements),
+              token(node.subsequent.else_keyword_loc),
+              visit(node.subsequent)
+            )
+          elsif node.if_keyword_loc.start_offset == node.location.start_offset
+            builder.condition(
+              token(node.if_keyword_loc),
+              visit(node.predicate),
+              if (then_keyword_loc = node.then_keyword_loc)
+                token(then_keyword_loc)
+              else
+                srange_semicolon(node.predicate.location.end_offset, (node.statements&.location || node.subsequent&.location || node.end_keyword_loc).start_offset)
+              end,
+              visit(node.statements),
+              case node.subsequent
+              when IfNode
+                token(node.subsequent.if_keyword_loc)
+              when ElseNode
+                token(node.subsequent.else_keyword_loc)
+              end,
+              visit(node.subsequent),
+              if node.if_keyword != "elsif"
+                token(node.end_keyword_loc)
+              end
+            )
+          else
+            builder.condition_mod(
+              visit(node.statements),
+              visit(node.subsequent),
+              token(node.if_keyword_loc),
+              visit(node.predicate)
+            )
+          end
+        end
+
+        # 1i
+        # ^^
+        def visit_imaginary_node(node)
+          visit_numeric(node, builder.complex([Complex(0, node.numeric.value), srange(node.location)]))
+        end
+
+        # { foo: }
+        #   ^^^^
+        def visit_implicit_node(node)
+          raise CompilationError, "Cannot directly compile implicit nodes"
+        end
+
+        # foo { |bar,| }
+        #           ^
+        def visit_implicit_rest_node(node)
+          raise CompilationError, "Cannot compile implicit rest nodes"
+        end
+
+        # case foo; in bar; end
+        # ^^^^^^^^^^^^^^^^^^^^^
+        def visit_in_node(node)
+          pattern = nil
+          guard = nil
+
+          case node.pattern
+          when IfNode
+            pattern = within_pattern { |compiler| node.pattern.statements.accept(compiler) }
+            guard = builder.if_guard(token(node.pattern.if_keyword_loc), visit(node.pattern.predicate))
+          when UnlessNode
+            pattern = within_pattern { |compiler| node.pattern.statements.accept(compiler) }
+            guard = builder.unless_guard(token(node.pattern.keyword_loc), visit(node.pattern.predicate))
+          else
+            pattern = within_pattern { |compiler| node.pattern.accept(compiler) }
+          end
+
+          builder.in_pattern(
+            token(node.in_loc),
+            pattern,
+            guard,
+            if (then_loc = node.then_loc)
+              token(then_loc)
+            else
+              srange_semicolon(node.pattern.location.end_offset, node.statements&.location&.start_offset)
+            end,
+            visit(node.statements)
+          )
+        end
+
+        # foo[bar] += baz
+        # ^^^^^^^^^^^^^^^
+        def visit_index_operator_write_node(node)
+          arguments = node.arguments&.arguments || []
+          arguments << node.block if node.block
+
+          builder.op_assign(
+            builder.index(
+              visit(node.receiver),
+              token(node.opening_loc),
+              visit_all(arguments),
+              token(node.closing_loc)
+            ),
+            [node.binary_operator_loc.slice.chomp("="), srange(node.binary_operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # foo[bar] &&= baz
+        # ^^^^^^^^^^^^^^^^
+        def visit_index_and_write_node(node)
+          arguments = node.arguments&.arguments || []
+          arguments << node.block if node.block
+
+          builder.op_assign(
+            builder.index(
+              visit(node.receiver),
+              token(node.opening_loc),
+              visit_all(arguments),
+              token(node.closing_loc)
+            ),
+            [node.operator_loc.slice.chomp("="), srange(node.operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # foo[bar] ||= baz
+        # ^^^^^^^^^^^^^^^^
+        def visit_index_or_write_node(node)
+          arguments = node.arguments&.arguments || []
+          arguments << node.block if node.block
+
+          builder.op_assign(
+            builder.index(
+              visit(node.receiver),
+              token(node.opening_loc),
+              visit_all(arguments),
+              token(node.closing_loc)
+            ),
+            [node.operator_loc.slice.chomp("="), srange(node.operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # foo[bar], = 1
+        # ^^^^^^^^
+        def visit_index_target_node(node)
+          builder.index_asgn(
+            visit(node.receiver),
+            token(node.opening_loc),
+            visit_all(node.arguments&.arguments || []),
+            token(node.closing_loc),
+          )
+        end
+
+        # @foo
+        # ^^^^
+        def visit_instance_variable_read_node(node)
+          builder.ivar(token(node.location))
+        end
+
+        # @foo = 1
+        # ^^^^^^^^
+        def visit_instance_variable_write_node(node)
+          builder.assign(
+            builder.assignable(builder.ivar(token(node.name_loc))),
+            token(node.operator_loc),
+            visit(node.value)
+          )
+        end
+
+        # @foo += bar
+        # ^^^^^^^^^^^
+        def visit_instance_variable_operator_write_node(node)
+          builder.op_assign(
+            builder.assignable(builder.ivar(token(node.name_loc))),
+            [node.binary_operator_loc.slice.chomp("="), srange(node.binary_operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # @foo &&= bar
+        # ^^^^^^^^^^^^
+        def visit_instance_variable_and_write_node(node)
+          builder.op_assign(
+            builder.assignable(builder.ivar(token(node.name_loc))),
+            [node.operator_loc.slice.chomp("="), srange(node.operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # @foo ||= bar
+        # ^^^^^^^^^^^^
+        def visit_instance_variable_or_write_node(node)
+          builder.op_assign(
+            builder.assignable(builder.ivar(token(node.name_loc))),
+            [node.operator_loc.slice.chomp("="), srange(node.operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # @foo, = bar
+        # ^^^^
+        def visit_instance_variable_target_node(node)
+          builder.assignable(builder.ivar(token(node.location)))
+        end
+
+        # 1
+        # ^
+        def visit_integer_node(node)
+          visit_numeric(node, builder.integer([node.value, srange(node.location)]))
+        end
+
+        # /foo #{bar}/
+        # ^^^^^^^^^^^^
+        def visit_interpolated_regular_expression_node(node)
+          builder.regexp_compose(
+            token(node.opening_loc),
+            string_nodes_from_interpolation(node, node.opening),
+            [node.closing[0], srange_offsets(node.closing_loc.start_offset, node.closing_loc.start_offset + 1)],
+            builder.regexp_options([node.closing[1..], srange_offsets(node.closing_loc.start_offset + 1, node.closing_loc.end_offset)])
+          )
+        end
+
+        # if /foo #{bar}/ then end
+        #    ^^^^^^^^^^^^
+        alias visit_interpolated_match_last_line_node visit_interpolated_regular_expression_node
+
+        # "foo #{bar}"
+        # ^^^^^^^^^^^^
+        def visit_interpolated_string_node(node)
+          if node.heredoc?
+            return visit_heredoc(node) { |children, closing| builder.string_compose(token(node.opening_loc), children, closing) }
+          end
+
+          builder.string_compose(
+            token(node.opening_loc),
+            string_nodes_from_interpolation(node, node.opening),
+            token(node.closing_loc)
+          )
+        end
+
+        # :"foo #{bar}"
+        # ^^^^^^^^^^^^^
+        def visit_interpolated_symbol_node(node)
+          builder.symbol_compose(
+            token(node.opening_loc),
+            string_nodes_from_interpolation(node, node.opening),
+            token(node.closing_loc)
+          )
+        end
+
+        # `foo #{bar}`
+        # ^^^^^^^^^^^^
+        def visit_interpolated_x_string_node(node)
+          if node.heredoc?
+            return visit_heredoc(node) { |children, closing| builder.xstring_compose(token(node.opening_loc), children, closing) }
+          end
+
+          builder.xstring_compose(
+            token(node.opening_loc),
+            string_nodes_from_interpolation(node, node.opening),
+            token(node.closing_loc)
+          )
+        end
+
+        # -> { it }
+        #      ^^
+        def visit_it_local_variable_read_node(node)
+          builder.ident([:it, srange(node.location)]).updated(:lvar)
+        end
+
+        # -> { it }
+        # ^^^^^^^^^
+        def visit_it_parameters_node(node)
+          # FIXME: The builder _should_ always be a subclass of the prism builder.
+          # Currently RuboCop passes in its own builder that always inherits from the
+          # parser builder (which is lacking the `itarg` method). Once rubocop-ast
+          # opts in to use the custom prism builder a warning can be emitted when
+          # it is not the expected class, and eventually raise.
+          # https://github.com/rubocop/rubocop-ast/pull/354
+          if builder.is_a?(Translation::Parser::Builder)
+            builder.itarg
+          else
+            builder.args(nil, [], nil, false)
+          end
+        end
+
+        # foo(bar: baz)
+        #     ^^^^^^^^
+        def visit_keyword_hash_node(node)
+          builder.associate(nil, visit_all(node.elements), nil)
+        end
+
+        # def foo(**bar); end
+        #         ^^^^^
+        #
+        # def foo(**); end
+        #         ^^
+        def visit_keyword_rest_parameter_node(node)
+          builder.kwrestarg(
+            token(node.operator_loc),
+            node.name ? [node.name, srange(node.name_loc)] : nil
+          )
+        end
+
+        # -> {}
+        # ^^^^^
+        def visit_lambda_node(node)
+          parameters = node.parameters
+          implicit_parameters = parameters.is_a?(NumberedParametersNode) || parameters.is_a?(ItParametersNode)
+
+          builder.block(
+            builder.call_lambda(token(node.operator_loc)),
+            [node.opening, srange(node.opening_loc)],
+            if parameters.nil?
+              builder.args(nil, [], nil, false)
+            elsif implicit_parameters
+              visit(node.parameters)
+            else
+              builder.args(
+                token(node.parameters.opening_loc),
+                visit(node.parameters),
+                token(node.parameters.closing_loc),
+                false
+              )
+            end,
+            visit(node.body),
+            [node.closing, srange(node.closing_loc)]
+          )
+        end
+
+        # foo
+        # ^^^
+        def visit_local_variable_read_node(node)
+          builder.ident([node.name, srange(node.location)]).updated(:lvar)
+        end
+
+        # foo = 1
+        # ^^^^^^^
+        def visit_local_variable_write_node(node)
+          builder.assign(
+            builder.assignable(builder.ident(token(node.name_loc))),
+            token(node.operator_loc),
+            visit(node.value)
+          )
+        end
+
+        # foo += bar
+        # ^^^^^^^^^^
+        def visit_local_variable_operator_write_node(node)
+          builder.op_assign(
+            builder.assignable(builder.ident(token(node.name_loc))),
+            [node.binary_operator_loc.slice.chomp("="), srange(node.binary_operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # foo &&= bar
+        # ^^^^^^^^^^^
+        def visit_local_variable_and_write_node(node)
+          builder.op_assign(
+            builder.assignable(builder.ident(token(node.name_loc))),
+            [node.operator_loc.slice.chomp("="), srange(node.operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # foo ||= bar
+        # ^^^^^^^^^^^
+        def visit_local_variable_or_write_node(node)
+          builder.op_assign(
+            builder.assignable(builder.ident(token(node.name_loc))),
+            [node.operator_loc.slice.chomp("="), srange(node.operator_loc)],
+            visit(node.value)
+          )
+        end
+
+        # foo, = bar
+        # ^^^
+        def visit_local_variable_target_node(node)
+          if in_pattern
+            builder.assignable(builder.match_var([node.name, srange(node.location)]))
+          else
+            builder.assignable(builder.ident(token(node.location)))
+          end
+        end
+
+        # foo in bar
+        # ^^^^^^^^^^
+        def visit_match_predicate_node(node)
+          builder.match_pattern_p(
+            visit(node.value),
+            token(node.operator_loc),
+            within_pattern { |compiler| node.pattern.accept(compiler) }
+          )
+        end
+
+        # foo => bar
+        # ^^^^^^^^^^
+        def visit_match_required_node(node)
+          builder.match_pattern(
+            visit(node.value),
+            token(node.operator_loc),
+            within_pattern { |compiler| node.pattern.accept(compiler) }
+          )
+        end
+
+        # /(?<foo>foo)/ =~ bar
+        # ^^^^^^^^^^^^^^^^^^^^
+        def visit_match_write_node(node)
+          builder.match_op(
+            visit(node.call.receiver),
+            token(node.call.message_loc),
+            visit(node.call.arguments.arguments.first)
+          )
+        end
+
+        # A node that is missing from the syntax tree. This is only used in the
+        # case of a syntax error. The parser gem doesn't have such a concept, so
+        # we invent our own here.
+        def visit_error_recovery_node(node)
+          ::AST::Node.new(:missing, [], location: ::Parser::Source::Map.new(srange(node.location)))
+        end
+
+        # module Foo; end
+        # ^^^^^^^^^^^^^^^
+        def visit_module_node(node)
+          builder.def_module(
+            token(node.module_keyword_loc),
+            visit(node.constant_path),
+            node.body&.accept(copy_compiler(forwarding: [])),
+            token(node.end_keyword_loc)
+          )
+        end
+
+        # foo, bar = baz
+        # ^^^^^^^^
+        def visit_multi_target_node(node)
+          builder.multi_lhs(
+            token(node.lparen_loc),
+            visit_all(multi_target_elements(node)),
+            token(node.rparen_loc)
+          )
+        end
+
+        # foo, bar = baz
+        # ^^^^^^^^^^^^^^
+        def visit_multi_write_node(node)
+          elements = multi_target_elements(node)
+
+          if elements.length == 1 && elements.first.is_a?(MultiTargetNode) && !node.rest
+            elements = multi_target_elements(elements.first)
+          end
+
+          builder.multi_assign(
+            builder.multi_lhs(
+              token(node.lparen_loc),
+              visit_all(elements),
+              token(node.rparen_loc)
+            ),
+            token(node.operator_loc),
+            visit(node.value)
+          )
+        end
+
+        # next
+        # ^^^^
+        #
+        # next foo
+        # ^^^^^^^^
+        def visit_next_node(node)
+          builder.keyword_cmd(
+            :next,
+            token(node.keyword_loc),
+            nil,
+            visit(node.arguments) || [],
+            nil
+          )
+        end
+
+        # nil
+        # ^^^
+        def visit_nil_node(node)
+          builder.nil(token(node.location))
+        end
+
+        # def foo(&nil); end
+        #         ^^^^
+        def visit_no_block_parameter_node(node)
+          builder.blocknilarg(token(node.operator_loc), token(node.keyword_loc))
+        end
+
+        # def foo(**nil); end
+        #         ^^^^^
+        def visit_no_keywords_parameter_node(node)
+          if in_pattern
+            builder.match_nil_pattern(token(node.operator_loc), token(node.keyword_loc))
+          else
+            builder.kwnilarg(token(node.operator_loc), token(node.keyword_loc))
+          end
+        end
+
+        # -> { _1 + _2 }
+        # ^^^^^^^^^^^^^^
+        def visit_numbered_parameters_node(node)
+          builder.numargs(node.maximum)
+        end
+
+        # $1
+        # ^^
+        def visit_numbered_reference_read_node(node)
+          builder.nth_ref([node.number, srange(node.location)])
+        end
+
+        # def foo(bar: baz); end
+        #         ^^^^^^^^
+        def visit_optional_keyword_parameter_node(node)
+          builder.kwoptarg([node.name, srange(node.name_loc)], visit(node.value))
+        end
+
+        # def foo(bar = 1); end
+        #         ^^^^^^^
+        def visit_optional_parameter_node(node)
+          builder.optarg(token(node.name_loc), token(node.operator_loc), visit(node.value))
+        end
+
+        # a or b
+        # ^^^^^^
+        def visit_or_node(node)
+          builder.logical_op(:or, visit(node.left), token(node.operator_loc), visit(node.right))
+        end
+
+        # def foo(bar, *baz); end
+        #         ^^^^^^^^^
+        def visit_parameters_node(node)
+          params = []
+
+          if node.requireds.any?
+            node.requireds.each do |required|
+              params <<
+                if required.is_a?(RequiredParameterNode)
+                  visit(required)
+                else
+                  required.accept(copy_compiler(in_destructure: true))
+                end
+            end
+          end
+
+          params.concat(visit_all(node.optionals)) if node.optionals.any?
+          params << visit(node.rest) if !node.rest.nil? && !node.rest.is_a?(ImplicitRestNode)
+
+          if node.posts.any?
+            node.posts.each do |post|
+              params <<
+                if post.is_a?(RequiredParameterNode)
+                  visit(post)
+                else
+                  post.accept(copy_compiler(in_destructure: true))
+                end
+            end
+          end
+
+          params.concat(visit_all(node.keywords)) if node.keywords.any?
+          params << visit(node.keyword_rest) if !node.keyword_rest.nil?
+          params << visit(node.block) if !node.block.nil?
+          params
+        end
+
+        # ()
+        # ^^
+        #
+        # (1)
+        # ^^^
+        def visit_parentheses_node(node)
+          builder.begin(
+            token(node.opening_loc),
+            visit(node.body),
+            token(node.closing_loc)
+          )
+        end
+
+        # foo => ^(bar)
+        #        ^^^^^^
+        def visit_pinned_expression_node(node)
+          parts = node.expression.accept(copy_compiler(in_pattern: false)) # Don't treat * and similar as match_rest
+          expression = builder.begin(token(node.lparen_loc), parts, token(node.rparen_loc))
+          builder.pin(token(node.operator_loc), expression)
+        end
+
+        # foo = 1 and bar => ^foo
+        #                    ^^^^
+        def visit_pinned_variable_node(node)
+          builder.pin(token(node.operator_loc), visit(node.variable))
+        end
+
+        # END {}
+        def visit_post_execution_node(node)
+          builder.postexe(
+            token(node.keyword_loc),
+            token(node.opening_loc),
+            visit(node.statements),
+            token(node.closing_loc)
+          )
+        end
+
+        # BEGIN {}
+        def visit_pre_execution_node(node)
+          builder.preexe(
+            token(node.keyword_loc),
+            token(node.opening_loc),
+            visit(node.statements),
+            token(node.closing_loc)
+          )
+        end
+
+        # The top-level program node.
+        def visit_program_node(node)
+          visit(node.statements)
+        end
+
+        # 0..5
+        # ^^^^
+        def visit_range_node(node)
+          if node.exclude_end?
+            builder.range_exclusive(
+              visit(node.left),
+              token(node.operator_loc),
+              visit(node.right)
+            )
+          else
+            builder.range_inclusive(
+              visit(node.left),
+              token(node.operator_loc),
+              visit(node.right)
+            )
+          end
+        end
+
+        # if foo .. bar; end
+        #    ^^^^^^^^^^
+        alias visit_flip_flop_node visit_range_node
+
+        # 1r
+        # ^^
+        def visit_rational_node(node)
+          visit_numeric(node, builder.rational([node.value, srange(node.location)]))
+        end
+
+        # redo
+        # ^^^^
+        def visit_redo_node(node)
+          builder.keyword_cmd(:redo, token(node.location))
+        end
+
+        # /foo/
+        # ^^^^^
+        def visit_regular_expression_node(node)
+          parts =
+            if node.content == ""
+              []
+            elsif node.content.include?("\n")
+              string_nodes_from_line_continuations(node.unescaped, node.content, node.content_loc.start_offset, node.opening)
+            else
+              [builder.string_internal([node.unescaped, srange(node.content_loc)])]
+            end
+
+          builder.regexp_compose(
+            token(node.opening_loc),
+            parts,
+            [node.closing[0], srange_offsets(node.closing_loc.start_offset, node.closing_loc.start_offset + 1)],
+            builder.regexp_options([node.closing[1..], srange_offsets(node.closing_loc.start_offset + 1, node.closing_loc.end_offset)])
+          )
+        end
+
+        # if /foo/ then end
+        #    ^^^^^
+        alias visit_match_last_line_node visit_regular_expression_node
+
+        # def foo(bar:); end
+        #         ^^^^
+        def visit_required_keyword_parameter_node(node)
+          builder.kwarg([node.name, srange(node.name_loc)])
+        end
+
+        # def foo(bar); end
+        #         ^^^
+        def visit_required_parameter_node(node)
+          builder.arg(token(node.location))
+        end
+
+        # foo rescue bar
+        # ^^^^^^^^^^^^^^
+        def visit_rescue_modifier_node(node)
+          builder.begin_body(
+            visit(node.expression),
+            [
+              builder.rescue_body(
+                token(node.keyword_loc),
+                nil,
+                nil,
+                nil,
+                nil,
+                visit(node.rescue_expression)
+              )
+            ]
+          )
+        end
+
+        # begin; rescue; end
+        #        ^^^^^^^
+        def visit_rescue_node(node)
+          raise CompilationError, "Cannot directly compile rescue nodes"
+        end
+
+        # def foo(*bar); end
+        #         ^^^^
+        #
+        # def foo(*); end
+        #         ^
+        def visit_rest_parameter_node(node)
+          builder.restarg(token(node.operator_loc), token(node.name_loc))
+        end
+
+        # retry
+        # ^^^^^
+        def visit_retry_node(node)
+          builder.keyword_cmd(:retry, token(node.location))
+        end
+
+        # return
+        # ^^^^^^
+        #
+        # return 1
+        # ^^^^^^^^
+        def visit_return_node(node)
+          builder.keyword_cmd(
+            :return,
+            token(node.keyword_loc),
+            nil,
+            visit(node.arguments) || [],
+            nil
+          )
+        end
+
+        # self
+        # ^^^^
+        def visit_self_node(node)
+          builder.self(token(node.location))
+        end
+
+        # A shareable constant.
+        def visit_shareable_constant_node(node)
+          visit(node.write)
+        end
+
+        # class << self; end
+        # ^^^^^^^^^^^^^^^^^^
+        def visit_singleton_class_node(node)
+          builder.def_sclass(
+            token(node.class_keyword_loc),
+            token(node.operator_loc),
+            visit(node.expression),
+            node.body&.accept(copy_compiler(forwarding: [])),
+            token(node.end_keyword_loc)
+          )
+        end
+
+        # __ENCODING__
+        # ^^^^^^^^^^^^
+        def visit_source_encoding_node(node)
+          builder.accessible(builder.__ENCODING__(token(node.location)))
+        end
+
+        # __FILE__
+        # ^^^^^^^^
+        def visit_source_file_node(node)
+          builder.accessible(builder.__FILE__(token(node.location)))
+        end
+
+        # __LINE__
+        # ^^^^^^^^
+        def visit_source_line_node(node)
+          builder.accessible(builder.__LINE__(token(node.location)))
+        end
+
+        # foo(*bar)
+        #     ^^^^
+        #
+        # def foo((bar, *baz)); end
+        #               ^^^^
+        #
+        # def foo(*); bar(*); end
+        #                 ^
+        def visit_splat_node(node)
+          if node.expression.nil? && forwarding.include?(:*)
+            builder.forwarded_restarg(token(node.operator_loc))
+          elsif in_destructure
+            builder.restarg(token(node.operator_loc), token(node.expression&.location))
+          elsif in_pattern
+            builder.match_rest(token(node.operator_loc), token(node.expression&.location))
+          else
+            builder.splat(token(node.operator_loc), visit(node.expression))
+          end
+        end
+
+        # A list of statements.
+        def visit_statements_node(node)
+          builder.compstmt(visit_all(node.body))
+        end
+
+        # "foo"
+        # ^^^^^
+        def visit_string_node(node)
+          if node.heredoc?
+            visit_heredoc(node.to_interpolated) { |children, closing| builder.string_compose(token(node.opening_loc), children, closing) }
+          elsif node.opening == "?"
+            builder.character([node.unescaped, srange(node.location)])
+          elsif node.opening&.start_with?("%") && node.unescaped.empty?
+            builder.string_compose(token(node.opening_loc), [], token(node.closing_loc))
+          else
+            parts =
+              if node.content.include?("\n")
+                string_nodes_from_line_continuations(node.unescaped, node.content, node.content_loc.start_offset, node.opening)
+              else
+                [builder.string_internal([node.unescaped, srange(node.content_loc)])]
+              end
+
+            builder.string_compose(
+              token(node.opening_loc),
+              parts,
+              token(node.closing_loc)
+            )
+          end
+        end
+
+        # super(foo)
+        # ^^^^^^^^^^
+        def visit_super_node(node)
+          arguments = node.arguments&.arguments || []
+          block = node.block
+
+          if block.is_a?(BlockArgumentNode)
+            arguments = [*arguments, block]
+            block = nil
+          end
+
+          visit_block(
+            builder.keyword_cmd(
+              :super,
+              token(node.keyword_loc),
+              token(node.lparen_loc),
+              visit_all(arguments),
+              token(node.rparen_loc)
+            ),
+            block
+          )
+        end
+
+        # :foo
+        # ^^^^
+        def visit_symbol_node(node)
+          if node.closing_loc.nil?
+            if node.opening_loc.nil?
+              builder.symbol_internal([node.unescaped, srange(node.location)])
+            else
+              builder.symbol([node.unescaped, srange(node.location)])
+            end
+          else
+            parts =
+              if node.value_loc.nil?
+                []
+              elsif node.value.include?("\n")
+                string_nodes_from_line_continuations(node.unescaped, node.value, node.value_loc.start_offset, node.opening)
+              else
+                [builder.string_internal([node.unescaped, srange(node.value_loc)])]
+              end
+
+            builder.symbol_compose(
+              token(node.opening_loc),
+              parts,
+              token(node.closing_loc)
+            )
+          end
+        end
+
+        # true
+        # ^^^^
+        def visit_true_node(node)
+          builder.true(token(node.location))
+        end
+
+        # undef foo
+        # ^^^^^^^^^
+        def visit_undef_node(node)
+          builder.undef_method(token(node.keyword_loc), visit_all(node.names))
+        end
+
+        # unless foo; bar end
+        # ^^^^^^^^^^^^^^^^^^^
+        #
+        # bar unless foo
+        # ^^^^^^^^^^^^^^
+        def visit_unless_node(node)
+          if node.keyword_loc.start_offset == node.location.start_offset
+            builder.condition(
+              token(node.keyword_loc),
+              visit(node.predicate),
+              if (then_keyword_loc = node.then_keyword_loc)
+                token(then_keyword_loc)
+              else
+                srange_semicolon(node.predicate.location.end_offset, (node.statements&.location || node.else_clause&.location || node.end_keyword_loc).start_offset)
+              end,
+              visit(node.else_clause),
+              token(node.else_clause&.else_keyword_loc),
+              visit(node.statements),
+              token(node.end_keyword_loc)
+            )
+          else
+            builder.condition_mod(
+              visit(node.else_clause),
+              visit(node.statements),
+              token(node.keyword_loc),
+              visit(node.predicate)
+            )
+          end
+        end
+
+        # until foo; bar end
+        # ^^^^^^^^^^^^^^^^^^
+        #
+        # bar until foo
+        # ^^^^^^^^^^^^^
+        def visit_until_node(node)
+          if node.location.start_offset == node.keyword_loc.start_offset
+            builder.loop(
+              :until,
+              token(node.keyword_loc),
+              visit(node.predicate),
+              if (do_keyword_loc = node.do_keyword_loc)
+                token(do_keyword_loc)
+              else
+                srange_semicolon(node.predicate.location.end_offset, (node.statements&.location || node.closing_loc).start_offset)
+              end,
+              visit(node.statements),
+              token(node.closing_loc)
+            )
+          else
+            builder.loop_mod(
+              :until,
+              visit(node.statements),
+              token(node.keyword_loc),
+              visit(node.predicate)
+            )
+          end
+        end
+
+        # case foo; when bar; end
+        #           ^^^^^^^^^^^^^
+        def visit_when_node(node)
+          builder.when(
+            token(node.keyword_loc),
+            visit_all(node.conditions),
+            if (then_keyword_loc = node.then_keyword_loc)
+              token(then_keyword_loc)
+            else
+              srange_semicolon(node.conditions.last.location.end_offset, node.statements&.location&.start_offset)
+            end,
+            visit(node.statements)
+          )
+        end
+
+        # while foo; bar end
+        # ^^^^^^^^^^^^^^^^^^
+        #
+        # bar while foo
+        # ^^^^^^^^^^^^^
+        def visit_while_node(node)
+          if node.location.start_offset == node.keyword_loc.start_offset
+            builder.loop(
+              :while,
+              token(node.keyword_loc),
+              visit(node.predicate),
+              if (do_keyword_loc = node.do_keyword_loc)
+                token(do_keyword_loc)
+              else
+                srange_semicolon(node.predicate.location.end_offset, (node.statements&.location || node.closing_loc).start_offset)
+              end,
+              visit(node.statements),
+              token(node.closing_loc)
+            )
+          else
+            builder.loop_mod(
+              :while,
+              visit(node.statements),
+              token(node.keyword_loc),
+              visit(node.predicate)
+            )
+          end
+        end
+
+        # `foo`
+        # ^^^^^
+        def visit_x_string_node(node)
+          if node.heredoc?
+            return visit_heredoc(node.to_interpolated) { |children, closing| builder.xstring_compose(token(node.opening_loc), children, closing) }
+          end
+
+          parts =
+            if node.content == ""
+              []
+            elsif node.content.include?("\n")
+              string_nodes_from_line_continuations(node.unescaped, node.content, node.content_loc.start_offset, node.opening)
+            else
+              [builder.string_internal([node.unescaped, srange(node.content_loc)])]
+            end
+
+          builder.xstring_compose(
+            token(node.opening_loc),
+            parts,
+            token(node.closing_loc)
+          )
+        end
+
+        # yield
+        # ^^^^^
+        #
+        # yield 1
+        # ^^^^^^^
+        def visit_yield_node(node)
+          builder.keyword_cmd(
+            :yield,
+            token(node.keyword_loc),
+            token(node.lparen_loc),
+            visit(node.arguments) || [],
+            token(node.rparen_loc)
+          )
+        end
+
+        private
+
+        # Initialize a new compiler with the given option overrides, used to
+        # visit a subtree with the given options.
+        def copy_compiler(forwarding: self.forwarding, in_destructure: self.in_destructure, in_pattern: self.in_pattern)
+          Compiler.new(parser, offset_cache, forwarding: forwarding, in_destructure: in_destructure, in_pattern: in_pattern)
+        end
+
+        # When *, **, &, or ... are used as an argument in a method call, we
+        # check if they were allowed by the current context. To determine that
+        # we build this lookup table.
+        def find_forwarding(node)
+          return [] if node.nil?
+
+          forwarding = []
+          forwarding << :* if node.rest.is_a?(RestParameterNode) && node.rest.name.nil?
+          forwarding << :** if node.keyword_rest.is_a?(KeywordRestParameterNode) && node.keyword_rest.name.nil?
+          forwarding << :& if !node.block.nil? && node.block.name.nil?
+          forwarding |= [:&, :"..."] if node.keyword_rest.is_a?(ForwardingParameterNode)
+
+          forwarding
+        end
+
+        # Returns the set of targets for a MultiTargetNode or a MultiWriteNode.
+        def multi_target_elements(node)
+          elements = [*node.lefts]
+          elements << node.rest if !node.rest.nil? && !node.rest.is_a?(ImplicitRestNode)
+          elements.concat(node.rights)
+          elements
+        end
+
+        # Blocks can have a special set of parameters that automatically expand
+        # when given arrays if they have a single required parameter and no
+        # other parameters.
+        def procarg0?(parameters)
+          parameters &&
+            parameters.requireds.length == 1 &&
+            parameters.optionals.empty? &&
+            parameters.rest.nil? &&
+            parameters.posts.empty? &&
+            parameters.keywords.empty? &&
+            parameters.keyword_rest.nil? &&
+            parameters.block.nil?
+        end
+
+        # Locations in the parser gem AST are generated using this class. We
+        # store a reference to its constant to make it slightly faster to look
+        # up.
+        Range = ::Parser::Source::Range
+
+        # Constructs a new source range from the given start and end offsets.
+        def srange(location)
+          Range.new(source_buffer, offset_cache[location.start_offset], offset_cache[location.end_offset]) if location
+        end
+
+        # Constructs a new source range from the given start and end offsets.
+        def srange_offsets(start_offset, end_offset)
+          Range.new(source_buffer, offset_cache[start_offset], offset_cache[end_offset])
+        end
+
+        # Constructs a new source range by finding a semicolon between the given
+        # start offset and end offset. If the semicolon is not found, it returns
+        # nil. Importantly it does not search past newlines or comments.
+        #
+        # Note that end_offset is allowed to be nil, in which case this will
+        # search until the end of the string.
+        def srange_semicolon(start_offset, end_offset)
+          if (match = source_buffer.source.byteslice(start_offset...end_offset)[/\A\s*;/])
+            final_offset = start_offset + match.bytesize
+            [";", Range.new(source_buffer, offset_cache[final_offset - 1], offset_cache[final_offset])]
+          end
+        end
+
+        # Transform a location into a token that the parser gem expects.
+        def token(location)
+          [location.slice, Range.new(source_buffer, offset_cache[location.start_offset], offset_cache[location.end_offset])] if location
+        end
+
+        # Visit a block node on a call.
+        def visit_block(call, block)
+          if block
+            parameters = block.parameters
+            implicit_parameters = parameters.is_a?(NumberedParametersNode) || parameters.is_a?(ItParametersNode)
+
+            builder.block(
+              call,
+              token(block.opening_loc),
+              if parameters.nil?
+                builder.args(nil, [], nil, false)
+              elsif implicit_parameters
+                visit(parameters)
+              else
+                builder.args(
+                  token(parameters.opening_loc),
+                  if procarg0?(parameters.parameters)
+                    parameter = parameters.parameters.requireds.first
+                    visited = parameter.is_a?(RequiredParameterNode) ? visit(parameter) : parameter.accept(copy_compiler(in_destructure: true))
+                    [builder.procarg0(visited)].concat(visit_all(parameters.locals))
+                  else
+                    visit(parameters)
+                  end,
+                  token(parameters.closing_loc),
+                  false
+                )
+              end,
+              visit(block.body),
+              token(block.closing_loc)
+            )
+          else
+            call
+          end
+        end
+
+        # Visit a heredoc that can be either a string or an xstring.
+        def visit_heredoc(node)
+          children = Array.new
+          indented = false
+
+          # If this is a dedenting heredoc, then we need to insert the opening
+          # content into the children as well.
+          if node.opening.start_with?("<<~") && node.parts.length > 0 && !node.parts.first.is_a?(StringNode)
+            location = node.parts.first.location
+            location = location.copy(start_offset: location.start_offset - location.start_line_slice.bytesize)
+            children << builder.string_internal(token(location))
+            indented = true
+          end
+
+          node.parts.each do |part|
+            pushing =
+              if part.is_a?(StringNode) && part.content.include?("\n")
+                string_nodes_from_line_continuations(part.unescaped, part.content, part.location.start_offset, node.opening)
+              else
+                [visit(part)]
+              end
+
+            pushing.each do |child|
+              if child.type == :str && child.children.last == ""
+                # nothing
+              elsif child.type == :str && children.last && children.last.type == :str && !children.last.children.first.end_with?("\n")
+                appendee = children[-1]
+
+                location = appendee.loc
+                location = location.with_expression(location.expression.join(child.loc.expression))
+
+                children[-1] = appendee.updated(:str, ["#{appendee.children.first}#{child.children.first}"], location: location)
+              else
+                children << child
+              end
+            end
+          end
+
+          closing = node.closing
+          closing_t = [closing.chomp, srange_offsets(node.closing_loc.start_offset, node.closing_loc.end_offset - (closing[/\s+$/]&.length || 0))]
+          composed = yield children, closing_t
+
+          composed = composed.updated(nil, children[1..-1]) if indented
+          composed
+        end
+
+        # Visit a numeric node and account for the optional sign.
+        def visit_numeric(node, value)
+          if (slice = node.slice).match?(/^[+-]/)
+            builder.unary_num(
+              [slice[0].to_sym, srange_offsets(node.location.start_offset, node.location.start_offset + 1)],
+              value
+            )
+          else
+            value
+          end
+        end
+
+        # Within the given block, track that we're within a pattern.
+        def within_pattern
+          begin
+            parser.pattern_variables.push
+            yield copy_compiler(in_pattern: true)
+          ensure
+            parser.pattern_variables.pop
+          end
+        end
+
+        # When the content of a string node is split across multiple lines, the
+        # parser gem creates individual string nodes for each line the content is part of.
+        def string_nodes_from_interpolation(node, opening)
+          node.parts.flat_map do |part|
+            if part.type == :string_node && part.content.include?("\n") && part.opening_loc.nil?
+              string_nodes_from_line_continuations(part.unescaped, part.content, part.content_loc.start_offset, opening)
+            else
+              visit(part)
+            end
+          end
+        end
+
+        # Create parser string nodes from a single prism node. The parser gem
+        # "glues" strings together when a line continuation is encountered.
+        def string_nodes_from_line_continuations(unescaped, escaped, start_offset, opening)
+          unescaped = unescaped.lines
+          escaped = escaped.lines
+          percent_array = opening&.start_with?("%w", "%W", "%i", "%I")
+          regex = opening == "/" || opening&.start_with?("%r")
+
+          # Non-interpolating strings
+          if opening&.end_with?("'") || opening&.start_with?("%q", "%s", "%w", "%i")
+            current_length = 0
+            current_line = +""
+
+            escaped.filter_map.with_index do |escaped_line, index|
+              unescaped_line = unescaped.fetch(index, "")
+              current_length += escaped_line.bytesize
+              current_line << unescaped_line
+
+              # Glue line continuations together. Only %w and %i arrays can contain these.
+              if percent_array && escaped_line[/(\\)*\n$/, 1]&.length&.odd?
+                next unless index == escaped.count - 1
+              end
+              s = builder.string_internal([current_line, srange_offsets(start_offset, start_offset + current_length)])
+              start_offset += escaped_line.bytesize
+              current_line = +""
+              current_length = 0
+              s
+            end
+          else
+            escaped_lengths = []
+            normalized_lengths = []
+            # Keeps track of where an unescaped line should start a new token. An unescaped
+            # \n would otherwise be indistinguishable from the actual newline at the end of
+            # of the line. The parser gem only emits a new string node at "real" newlines,
+            # line continuations don't start a new node as well.
+            do_next_tokens = []
+
+            escaped
+              .chunk_while { |before, after| before[/(\\*)\r?\n$/, 1]&.length&.odd? || false }
+              .each do |lines|
+                escaped_lengths << lines.sum(&:bytesize)
+
+                unescaped_lines_count =
+                  if regex
+                    0 # Will always be preserved as is
+                  else
+                    lines.sum do |line|
+                      count = line.scan(/(\\*)n/).count { |(backslashes)| backslashes&.length&.odd? }
+                      count -= 1 if line.match?(/(?:\A|[^\\])(?:\\\\)*\\n\z/) && count > 0
+                      count
+                    end
+                  end
+
+                extra = 1
+                extra = lines.count if percent_array # Account for line continuations in percent arrays
+
+                normalized_lengths.concat(Array.new(unescaped_lines_count + extra, 0))
+                normalized_lengths[-1] = lines.sum { |line| line.bytesize }
+                do_next_tokens.concat(Array.new(unescaped_lines_count + extra, false))
+                do_next_tokens[-1] = true
+              end
+
+            current_line = +""
+            current_normalized_length = 0
+
+            emitted_count = 0
+            unescaped.filter_map.with_index do |unescaped_line, index|
+              current_line << unescaped_line
+              current_normalized_length += normalized_lengths.fetch(index, 0)
+
+              if do_next_tokens[index]
+                inner_part = builder.string_internal([current_line, srange_offsets(start_offset, start_offset + current_normalized_length)])
+                start_offset += escaped_lengths.fetch(emitted_count, 0)
+                current_line = +""
+                current_normalized_length = 0
+                emitted_count += 1
+                inner_part
+              else
+                nil
+              end
+            end
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/prism/translation/parser/lexer.rb b/lib/prism/translation/parser/lexer.rb
new file mode 100644
index 0000000000..e82042867f
--- /dev/null
+++ b/lib/prism/translation/parser/lexer.rb
@@ -0,0 +1,819 @@
+# frozen_string_literal: true
+# :markup: markdown
+
+require "strscan"
+require_relative "../../polyfill/append_as_bytes"
+require_relative "../../polyfill/scan_byte"
+
+module Prism
+  module Translation
+    class Parser
+      # Accepts a list of prism tokens and converts them into the expected
+      # format for the parser gem.
+      class Lexer # :nodoc:
+        # These tokens are always skipped
+        TYPES_ALWAYS_SKIP = Set.new(%i[IGNORED_NEWLINE __END__ EOF])
+        private_constant :TYPES_ALWAYS_SKIP
+
+        # The direct translating of types between the two lexers.
+        TYPES = {
+          # These tokens should never appear in the output of the lexer.
+          EMBDOC_END: nil,
+          EMBDOC_LINE: nil,
+
+          # These tokens have more or less direct mappings.
+          AMPERSAND: :tAMPER2,
+          AMPERSAND_AMPERSAND: :tANDOP,
+          AMPERSAND_AMPERSAND_EQUAL: :tOP_ASGN,
+          AMPERSAND_DOT: :tANDDOT,
+          AMPERSAND_EQUAL: :tOP_ASGN,
+          BACK_REFERENCE: :tBACK_REF,
+          BACKTICK: :tXSTRING_BEG,
+          BANG: :tBANG,
+          BANG_EQUAL: :tNEQ,
+          BANG_TILDE: :tNMATCH,
+          BRACE_LEFT: :tLCURLY,
+          BRACE_RIGHT: :tRCURLY,
+          BRACKET_LEFT: :tLBRACK2,
+          BRACKET_LEFT_ARRAY: :tLBRACK,
+          BRACKET_LEFT_RIGHT: :tAREF,
+          BRACKET_LEFT_RIGHT_EQUAL: :tASET,
+          BRACKET_RIGHT: :tRBRACK,
+          CARET: :tCARET,
+          CARET_EQUAL: :tOP_ASGN,
+          CHARACTER_LITERAL: :tCHARACTER,
+          CLASS_VARIABLE: :tCVAR,
+          COLON: :tCOLON,
+          COLON_COLON: :tCOLON2,
+          COMMA: :tCOMMA,
+          COMMENT: :tCOMMENT,
+          CONSTANT: :tCONSTANT,
+          DOT: :tDOT,
+          DOT_DOT: :tDOT2,
+          DOT_DOT_DOT: :tDOT3,
+          EMBDOC_BEGIN: :tCOMMENT,
+          EMBEXPR_BEGIN: :tSTRING_DBEG,
+          EMBEXPR_END: :tSTRING_DEND,
+          EMBVAR: :tSTRING_DVAR,
+          EQUAL: :tEQL,
+          EQUAL_EQUAL: :tEQ,
+          EQUAL_EQUAL_EQUAL: :tEQQ,
+          EQUAL_GREATER: :tASSOC,
+          EQUAL_TILDE: :tMATCH,
+          FLOAT: :tFLOAT,
+          FLOAT_IMAGINARY: :tIMAGINARY,
+          FLOAT_RATIONAL: :tRATIONAL,
+          FLOAT_RATIONAL_IMAGINARY: :tIMAGINARY,
+          GLOBAL_VARIABLE: :tGVAR,
+          GREATER: :tGT,
+          GREATER_EQUAL: :tGEQ,
+          GREATER_GREATER: :tRSHFT,
+          GREATER_GREATER_EQUAL: :tOP_ASGN,
+          HEREDOC_START: :tSTRING_BEG,
+          HEREDOC_END: :tSTRING_END,
+          IDENTIFIER: :tIDENTIFIER,
+          INSTANCE_VARIABLE: :tIVAR,
+          INTEGER: :tINTEGER,
+          INTEGER_IMAGINARY: :tIMAGINARY,
+          INTEGER_RATIONAL: :tRATIONAL,
+          INTEGER_RATIONAL_IMAGINARY: :tIMAGINARY,
+          KEYWORD_ALIAS: :kALIAS,
+          KEYWORD_AND: :kAND,
+          KEYWORD_BEGIN: :kBEGIN,
+          KEYWORD_BEGIN_UPCASE: :klBEGIN,
+          KEYWORD_BREAK: :kBREAK,
+          KEYWORD_CASE: :kCASE,
+          KEYWORD_CLASS: :kCLASS,
+          KEYWORD_DEF: :kDEF,
+          KEYWORD_DEFINED: :kDEFINED,
+          KEYWORD_DO: :kDO,
+          KEYWORD_DO_BLOCK: :kDO_BLOCK,
+          KEYWORD_DO_LOOP: :kDO_COND,
+          KEYWORD_END: :kEND,
+          KEYWORD_END_UPCASE: :klEND,
+          KEYWORD_ENSURE: :kENSURE,
+          KEYWORD_ELSE: :kELSE,
+          KEYWORD_ELSIF: :kELSIF,
+          KEYWORD_FALSE: :kFALSE,
+          KEYWORD_FOR: :kFOR,
+          KEYWORD_IF: :kIF,
+          KEYWORD_IF_MODIFIER: :kIF_MOD,
+          KEYWORD_IN: :kIN,
+          KEYWORD_MODULE: :kMODULE,
+          KEYWORD_NEXT: :kNEXT,
+          KEYWORD_NIL: :kNIL,
+          KEYWORD_NOT: :kNOT,
+          KEYWORD_OR: :kOR,
+          KEYWORD_REDO: :kREDO,
+          KEYWORD_RESCUE: :kRESCUE,
+          KEYWORD_RESCUE_MODIFIER: :kRESCUE_MOD,
+          KEYWORD_RETRY: :kRETRY,
+          KEYWORD_RETURN: :kRETURN,
+          KEYWORD_SELF: :kSELF,
+          KEYWORD_SUPER: :kSUPER,
+          KEYWORD_THEN: :kTHEN,
+          KEYWORD_TRUE: :kTRUE,
+          KEYWORD_UNDEF: :kUNDEF,
+          KEYWORD_UNLESS: :kUNLESS,
+          KEYWORD_UNLESS_MODIFIER: :kUNLESS_MOD,
+          KEYWORD_UNTIL: :kUNTIL,
+          KEYWORD_UNTIL_MODIFIER: :kUNTIL_MOD,
+          KEYWORD_WHEN: :kWHEN,
+          KEYWORD_WHILE: :kWHILE,
+          KEYWORD_WHILE_MODIFIER: :kWHILE_MOD,
+          KEYWORD_YIELD: :kYIELD,
+          KEYWORD___ENCODING__: :k__ENCODING__,
+          KEYWORD___FILE__: :k__FILE__,
+          KEYWORD___LINE__: :k__LINE__,
+          LABEL: :tLABEL,
+          LABEL_END: :tLABEL_END,
+          LAMBDA_BEGIN: :tLAMBEG,
+          LESS: :tLT,
+          LESS_EQUAL: :tLEQ,
+          LESS_EQUAL_GREATER: :tCMP,
+          LESS_LESS: :tLSHFT,
+          LESS_LESS_EQUAL: :tOP_ASGN,
+          METHOD_NAME: :tFID,
+          MINUS: :tMINUS,
+          MINUS_EQUAL: :tOP_ASGN,
+          MINUS_GREATER: :tLAMBDA,
+          NEWLINE: :tNL,
+          NUMBERED_REFERENCE: :tNTH_REF,
+          PARENTHESIS_LEFT: :tLPAREN2,
+          PARENTHESIS_LEFT_PARENTHESES: :tLPAREN_ARG,
+          PARENTHESIS_RIGHT: :tRPAREN,
+          PERCENT: :tPERCENT,
+          PERCENT_EQUAL: :tOP_ASGN,
+          PERCENT_LOWER_I: :tQSYMBOLS_BEG,
+          PERCENT_LOWER_W: :tQWORDS_BEG,
+          PERCENT_UPPER_I: :tSYMBOLS_BEG,
+          PERCENT_UPPER_W: :tWORDS_BEG,
+          PERCENT_LOWER_X: :tXSTRING_BEG,
+          PLUS: :tPLUS,
+          PLUS_EQUAL: :tOP_ASGN,
+          PIPE_EQUAL: :tOP_ASGN,
+          PIPE: :tPIPE,
+          PIPE_PIPE: :tOROP,
+          PIPE_PIPE_EQUAL: :tOP_ASGN,
+          QUESTION_MARK: :tEH,
+          REGEXP_BEGIN: :tREGEXP_BEG,
+          REGEXP_END: :tSTRING_END,
+          SEMICOLON: :tSEMI,
+          SLASH: :tDIVIDE,
+          SLASH_EQUAL: :tOP_ASGN,
+          STAR: :tSTAR2,
+          STAR_EQUAL: :tOP_ASGN,
+          STAR_STAR: :tPOW,
+          STAR_STAR_EQUAL: :tOP_ASGN,
+          STRING_BEGIN: :tSTRING_BEG,
+          STRING_CONTENT: :tSTRING_CONTENT,
+          STRING_END: :tSTRING_END,
+          SYMBOL_BEGIN: :tSYMBEG,
+          TILDE: :tTILDE,
+          UAMPERSAND: :tAMPER,
+          UCOLON_COLON: :tCOLON3,
+          UDOT_DOT: :tBDOT2,
+          UDOT_DOT_DOT: :tBDOT3,
+          UMINUS: :tUMINUS,
+          UMINUS_NUM: :tUNARY_NUM,
+          UPLUS: :tUPLUS,
+          USTAR: :tSTAR,
+          USTAR_STAR: :tDSTAR,
+          WORDS_SEP: :tSPACE
+        }
+
+        # These constants represent flags in our lex state. We really, really
+        # don't want to be using them and we really, really don't want to be
+        # exposing them as part of our public API. Unfortunately, we don't have
+        # another way of matching the exact tokens that the parser gem expects
+        # without them. We should find another way to do this, but in the
+        # meantime we'll hide them from the documentation and mark them as
+        # private constants.
+        EXPR_BEG = 0x1
+        EXPR_LABEL = 0x400
+
+        # It is used to determine whether `do` is of the token type `kDO` or `kDO_LAMBDA`.
+        #
+        # NOTE: In edge cases like `-> (foo = -> (bar) {}) do end`, please note that `kDO` is still returned
+        # instead of `kDO_LAMBDA`, which is expected: https://github.com/ruby/prism/pull/3046
+        LAMBDA_TOKEN_TYPES = Set.new([:kDO_LAMBDA, :tLAMBDA, :tLAMBEG])
+
+        # The `PARENTHESIS_LEFT` token in Prism is classified as either `tLPAREN` or `tLPAREN2` in the Parser gem.
+        # The following token types are listed as those classified as `tLPAREN`.
+        LPAREN_CONVERSION_TOKEN_TYPES = Set.new([
+          :kBREAK, :tCARET, :kCASE, :tDIVIDE, :kFOR, :kIF, :kNEXT, :kRETURN, :kUNTIL, :kWHILE, :tAMPER, :tANDOP, :tBANG, :tCOMMA, :tDOT2, :tDOT3,
+          :tEQL, :tLPAREN, :tLPAREN2, :tLPAREN_ARG, :tLSHFT, :tNL, :tOP_ASGN, :tOROP, :tPIPE, :tSEMI, :tSTRING_DBEG, :tUMINUS, :tUPLUS, :tLCURLY
+        ])
+
+        # Types of tokens that are allowed to continue a method call with comments in-between.
+        # For these, the parser gem doesn't emit a newline token after the last comment.
+        COMMENT_CONTINUATION_TYPES = Set.new([:COMMENT, :AMPERSAND_DOT, :DOT])
+        private_constant :COMMENT_CONTINUATION_TYPES
+
+        # Heredocs are complex and require us to keep track of a bit of info to refer to later
+        HeredocData = Struct.new(:identifier, :common_whitespace, keyword_init: true)
+
+        private_constant :TYPES, :EXPR_BEG, :EXPR_LABEL, :LAMBDA_TOKEN_TYPES, :LPAREN_CONVERSION_TOKEN_TYPES, :HeredocData
+
+        # The Parser::Source::Buffer that the tokens were lexed from.
+        attr_reader :source_buffer
+
+        # An array of tuples that contain prism tokens and their associated lex
+        # state when they were lexed.
+        attr_reader :lexed
+
+        # A hash that maps offsets in bytes to offsets in characters.
+        attr_reader :offset_cache
+
+        # Initialize the lexer with the given source buffer, prism tokens, and
+        # offset cache.
+        def initialize(source_buffer, lexed, offset_cache)
+          @source_buffer = source_buffer
+          @lexed = lexed
+          @offset_cache = offset_cache
+        end
+
+        Range = ::Parser::Source::Range
+        private_constant :Range
+
+        # Convert the prism tokens into the expected format for the parser gem.
+        def to_a
+          tokens = []
+
+          index = 0
+          length = lexed.length
+
+          heredoc_stack = []
+          quote_stack = []
+
+          # The parser gem emits the newline tokens for comments out of order. This saves
+          # that token location to emit at a later time to properly line everything up.
+          # https://github.com/whitequark/parser/issues/1025
+          comment_newline_location = nil
+
+          while index < length
+            token, state = lexed[index]
+            index += 1
+            next if TYPES_ALWAYS_SKIP.include?(token.type)
+
+            type = TYPES.fetch(token.type)
+            value = token.value
+            location = range(token.location.start_offset, token.location.end_offset)
+
+            case type
+            when :kDO
+              nearest_lambda_token = tokens.reverse_each.find do |token|
+                LAMBDA_TOKEN_TYPES.include?(token.first)
+              end
+
+              if nearest_lambda_token&.first == :tLAMBDA
+                type = :kDO_LAMBDA
+              end
+            when :tCHARACTER
+              value.delete_prefix!("?")
+              # Character literals behave similar to double-quoted strings. We can use the same escaping mechanism.
+              value = unescape_string(value, "?")
+            when :tCOMMENT
+              if token.type == :EMBDOC_BEGIN
+
+                while !((next_token = lexed[index]&.first) && next_token.type == :EMBDOC_END) && (index < length - 1)
+                  value += next_token.value
+                  index += 1
+                end
+
+                value += next_token.value
+                location = range(token.location.start_offset, next_token.location.end_offset)
+                index += 1
+              else
+                is_at_eol = value.chomp!.nil?
+                location = range(token.location.start_offset, token.location.end_offset + (is_at_eol ? 0 : -1))
+
+                prev_token, _ = lexed[index - 2] if index - 2 >= 0
+                next_token, _ = lexed[index]
+
+                is_inline_comment = prev_token&.location&.start_line == token.location.start_line
+                if is_inline_comment && !is_at_eol && !COMMENT_CONTINUATION_TYPES.include?(next_token&.type)
+                  tokens << [:tCOMMENT, [value, location]]
+
+                  nl_location = range(token.location.end_offset - 1, token.location.end_offset)
+                  tokens << [:tNL, [nil, nl_location]]
+                  next
+                elsif is_inline_comment && next_token&.type == :COMMENT
+                  comment_newline_location = range(token.location.end_offset - 1, token.location.end_offset)
+                elsif comment_newline_location && !COMMENT_CONTINUATION_TYPES.include?(next_token&.type)
+                  tokens << [:tCOMMENT, [value, location]]
+                  tokens << [:tNL, [nil, comment_newline_location]]
+                  comment_newline_location = nil
+                  next
+                end
+              end
+            when :tNL
+              next_token, _ = lexed[index]
+              # Newlines after comments are emitted out of order.
+              if next_token&.type == :COMMENT
+                comment_newline_location = location
+                next
+              end
+
+              value = nil
+            when :tFLOAT
+              value = parse_float(value)
+            when :tIMAGINARY
+              value = parse_complex(value)
+            when :tINTEGER
+              if value.start_with?("+")
+                tokens << [:tUNARY_NUM, ["+", range(token.location.start_offset, token.location.start_offset + 1)]]
+                location = range(token.location.start_offset + 1, token.location.end_offset)
+              end
+
+              value = parse_integer(value)
+            when :tLABEL
+              value.chomp!(":")
+            when :tLABEL_END
+              value.chomp!(":")
+            when :tLCURLY
+              type = :tLBRACE if state == EXPR_BEG | EXPR_LABEL
+            when :tLPAREN2
+              type = :tLPAREN if tokens.empty? || LPAREN_CONVERSION_TOKEN_TYPES.include?(tokens.dig(-1, 0))
+            when :tNTH_REF
+              value = parse_integer(value.delete_prefix("$"))
+            when :tOP_ASGN
+              value.chomp!("=")
+            when :tRATIONAL
+              value = parse_rational(value)
+            when :tSPACE
+              location = range(token.location.start_offset, token.location.start_offset + percent_array_leading_whitespace(value))
+              value = nil
+            when :tSTRING_BEG
+              next_token, _ = lexed[index]
+              next_next_token, _ = lexed[index + 1]
+              basic_quotes = value == '"' || value == "'"
+
+              if basic_quotes && next_token&.type == :STRING_END
+                next_location = token.location.join(next_token.location)
+                type = :tSTRING
+                value = ""
+                location = range(next_location.start_offset, next_location.end_offset)
+                index += 1
+              elsif value.start_with?("'", '"', "%")
+                if next_token&.type == :STRING_CONTENT && next_next_token&.type == :STRING_END
+                  string_value = next_token.value
+                  if simplify_string?(string_value, value)
+                    next_location = token.location.join(next_next_token.location)
+                    if percent_array?(value)
+                      value = percent_array_unescape(string_value)
+                    else
+                      value = unescape_string(string_value, value)
+                    end
+                    type = :tSTRING
+                    location = range(next_location.start_offset, next_location.end_offset)
+                    index += 2
+                    tokens << [type, [value, location]]
+
+                    next
+                  end
+                end
+
+                quote_stack.push(value)
+              elsif token.type == :HEREDOC_START
+                quote = value[2] == "-" || value[2] == "~" ? value[3] : value[2]
+                heredoc_type = value[2] == "-" || value[2] == "~" ? value[2] : ""
+                heredoc = HeredocData.new(
+                  identifier: value.match(/<<[-~]?["'`]?(?<heredoc_identifier>.*?)["'`]?\z/)[:heredoc_identifier],
+                  common_whitespace: 0,
+                )
+
+                if quote == "`"
+                  type = :tXSTRING_BEG
+                end
+
+                # The parser gem trims whitespace from squiggly heredocs. We must record
+                # the most common whitespace to later remove.
+                if heredoc_type == "~" || heredoc_type == "`"
+                  heredoc.common_whitespace = calculate_heredoc_whitespace(index)
+                end
+
+                if quote == "'" || quote == '"' || quote == "`"
+                  value = "<<#{quote}"
+                else
+                  value = '<<"'
+                end
+
+                heredoc_stack.push(heredoc)
+                quote_stack.push(value)
+              end
+            when :tSTRING_CONTENT
+              is_percent_array = percent_array?(quote_stack.last)
+
+              if (lines = token.value.lines).one?
+                # Prism usually emits a single token for strings with line continuations.
+                # For squiggly heredocs they are not joined so we do that manually here.
+                current_string = +""
+                current_length = 0
+                start_offset = token.location.start_offset
+                while token.type == :STRING_CONTENT
+                  current_length += token.value.bytesize
+                  # Heredoc interpolation can have multiple STRING_CONTENT nodes on the same line.
+                  prev_token, _ = lexed[index - 2] if index - 2 >= 0
+                  is_first_token_on_line = prev_token && token.location.start_line != prev_token.location.start_line
+                  # The parser gem only removes indentation when the heredoc is not nested
+                  not_nested = heredoc_stack.size == 1
+                  if is_percent_array
+                    value = percent_array_unescape(token.value)
+                  elsif is_first_token_on_line && not_nested && (current_heredoc = heredoc_stack.last).common_whitespace > 0
+                    value = trim_heredoc_whitespace(token.value, current_heredoc)
+                  end
+
+                  current_string << unescape_string(value, quote_stack.last)
+                  relevant_backslash_count = if quote_stack.last.start_with?("%W", "%I")
+                                               0 # the last backslash escapes the newline
+                                             else
+                                               token.value[/(\\{1,})\n/, 1]&.length || 0
+                                             end
+                  if relevant_backslash_count.even? || !interpolation?(quote_stack.last)
+                    tokens << [:tSTRING_CONTENT, [current_string, range(start_offset, start_offset + current_length)]]
+                    break
+                  end
+                  token, _ = lexed[index]
+                  index += 1
+                end
+              else
+                # When the parser gem encounters a line continuation inside of a multiline string,
+                # it emits a single string node. The backslash (and remaining newline) is removed.
+                current_line = +""
+                adjustment = 0
+                start_offset = token.location.start_offset
+                emit = false
+
+                lines.each.with_index do |line, index|
+                  chomped_line = line.chomp
+                  backslash_count = chomped_line[/\\{1,}\z/]&.length || 0
+                  is_interpolation = interpolation?(quote_stack.last)
+
+                  if backslash_count.odd? && (is_interpolation || is_percent_array)
+                    if is_percent_array
+                      current_line << percent_array_unescape(line)
+                      adjustment += 1
+                    else
+                      chomped_line.delete_suffix!("\\")
+                      current_line << chomped_line
+                      adjustment += 2
+                    end
+                    # If the string ends with a line continuation emit the remainder
+                    emit = index == lines.count - 1
+                  else
+                    current_line << line
+                    emit = true
+                  end
+
+                  if emit
+                    end_offset = start_offset + current_line.bytesize + adjustment
+                    tokens << [:tSTRING_CONTENT, [unescape_string(current_line, quote_stack.last), range(start_offset, end_offset)]]
+                    start_offset = end_offset
+                    current_line = +""
+                    adjustment = 0
+                  end
+                end
+              end
+              next
+            when :tSTRING_DVAR
+              value = nil
+            when :tSTRING_END
+              if token.type == :HEREDOC_END && value.end_with?("\n")
+                newline_length = value.end_with?("\r\n") ? 2 : 1
+                value = heredoc_stack.pop.identifier
+                location = range(token.location.start_offset, token.location.end_offset - newline_length)
+              elsif token.type == :REGEXP_END
+                value = value[0]
+                location = range(token.location.start_offset, token.location.start_offset + 1)
+              end
+
+              if percent_array?(quote_stack.pop)
+                prev_token, _ = lexed[index - 2] if index - 2 >= 0
+                empty = %i[PERCENT_LOWER_I PERCENT_LOWER_W PERCENT_UPPER_I PERCENT_UPPER_W].include?(prev_token&.type)
+                ends_with_whitespace = prev_token&.type == :WORDS_SEP
+                # parser always emits a space token after content in a percent array, even if no actual whitespace is present.
+                if !empty && !ends_with_whitespace
+                  tokens << [:tSPACE, [nil, range(token.location.start_offset, token.location.start_offset)]]
+                end
+              end
+            when :tSYMBEG
+              if (next_token = lexed[index]&.first) && next_token.type != :STRING_CONTENT && next_token.type != :EMBEXPR_BEGIN && next_token.type != :EMBVAR && next_token.type != :STRING_END
+                next_location = token.location.join(next_token.location)
+                type = :tSYMBOL
+                value = next_token.value
+                value = { "~@" => "~", "!@" => "!" }.fetch(value, value)
+                location = range(next_location.start_offset, next_location.end_offset)
+                index += 1
+              else
+                quote_stack.push(value)
+              end
+            when :tFID
+              if !tokens.empty? && tokens.dig(-1, 0) == :kDEF
+                type = :tIDENTIFIER
+              end
+            when :tXSTRING_BEG
+              if (next_token = lexed[index]&.first) && !%i[STRING_CONTENT STRING_END EMBEXPR_BEGIN].include?(next_token.type)
+                # self.`()
+                type = :tBACK_REF2
+              end
+              quote_stack.push(value)
+            when :tSYMBOLS_BEG, :tQSYMBOLS_BEG, :tWORDS_BEG, :tQWORDS_BEG
+              if (next_token = lexed[index]&.first) && next_token.type == :WORDS_SEP
+                index += 1
+              end
+
+              quote_stack.push(value)
+            when :tREGEXP_BEG
+              quote_stack.push(value)
+            end
+
+            tokens << [type, [value, location]]
+
+            if token.type == :REGEXP_END
+              tokens << [:tREGEXP_OPT, [token.value[1..], range(token.location.start_offset + 1, token.location.end_offset)]]
+            end
+          end
+
+          tokens
+        end
+
+        private
+
+        # Creates a new parser range, taking prisms byte offsets into account
+        def range(start_offset, end_offset)
+          Range.new(source_buffer, offset_cache[start_offset], offset_cache[end_offset])
+        end
+
+        # Parse an integer from the string representation.
+        def parse_integer(value)
+          Integer(value)
+        rescue ArgumentError
+          0
+        end
+
+        # Parse a float from the string representation.
+        def parse_float(value)
+          Float(value)
+        rescue ArgumentError
+          0.0
+        end
+
+        # Parse a complex from the string representation.
+        def parse_complex(value)
+          value.chomp!("i")
+
+          if value.end_with?("r")
+            Complex(0, parse_rational(value))
+          elsif value.start_with?(/0[BbOoDdXx]/)
+            Complex(0, parse_integer(value))
+          else
+            Complex(0, value)
+          end
+        rescue ArgumentError
+          0i
+        end
+
+        # Parse a rational from the string representation.
+        def parse_rational(value)
+          value.chomp!("r")
+
+          if value.start_with?(/0[BbOoDdXx]/)
+            Rational(parse_integer(value))
+          else
+            Rational(value)
+          end
+        rescue ArgumentError
+          0r
+        end
+
+        # Wonky heredoc tab/spaces rules.
+        # https://github.com/ruby/prism/blob/v1.3.0/src/prism.c#L10548-L10558
+        def calculate_heredoc_whitespace(heredoc_token_index)
+          next_token_index = heredoc_token_index
+          nesting_level = 0
+          previous_line = -1
+          result = Float::MAX
+
+          while (next_token = lexed[next_token_index]&.first)
+            next_token_index += 1
+            next_next_token, _ = lexed[next_token_index]
+            first_token_on_line = next_token.location.start_column == 0
+
+            # String content inside nested heredocs and interpolation is ignored
+            if next_token.type == :HEREDOC_START || next_token.type == :EMBEXPR_BEGIN
+              # When interpolation is the first token of a line there is no string
+              # content to check against. There will be no common whitespace.
+              if nesting_level == 0 && first_token_on_line
+                result = 0
+              end
+              nesting_level += 1
+            elsif next_token.type == :HEREDOC_END || next_token.type == :EMBEXPR_END
+              nesting_level -= 1
+              # When we encountered the matching heredoc end, we can exit
+              break if nesting_level == -1
+            elsif next_token.type == :STRING_CONTENT && nesting_level == 0 && first_token_on_line
+              common_whitespace = 0
+              next_token.value[/^\s*/].each_char do |char|
+                if char == "\t"
+                  common_whitespace = (common_whitespace / 8 + 1) * 8;
+                else
+                  common_whitespace += 1
+                end
+              end
+
+              is_first_token_on_line = next_token.location.start_line != previous_line
+              # Whitespace is significant if followed by interpolation
+              whitespace_only = common_whitespace == next_token.value.length && next_next_token&.location&.start_line != next_token.location.start_line
+              if is_first_token_on_line && !whitespace_only && common_whitespace < result
+                result = common_whitespace
+                previous_line = next_token.location.start_line
+              end
+            end
+          end
+          result
+        end
+
+        # Wonky heredoc tab/spaces rules.
+        # https://github.com/ruby/prism/blob/v1.3.0/src/prism.c#L16528-L16545
+        def trim_heredoc_whitespace(string, heredoc)
+          trimmed_whitespace = 0
+          trimmed_characters = 0
+          while (string[trimmed_characters] == "\t" || string[trimmed_characters] == " ") && trimmed_whitespace < heredoc.common_whitespace
+            if string[trimmed_characters] == "\t"
+              trimmed_whitespace = (trimmed_whitespace / 8 + 1) * 8;
+              break if trimmed_whitespace > heredoc.common_whitespace
+            else
+              trimmed_whitespace += 1
+            end
+            trimmed_characters += 1
+          end
+
+          string[trimmed_characters..]
+        end
+
+        # Escape sequences that have special and should appear unescaped in the resulting string.
+        ESCAPES = {
+          "a" => "\a", "b" => "\b", "e" => "\e", "f" => "\f",
+          "n" => "\n", "r" => "\r", "s" => "\s", "t" => "\t",
+          "v" => "\v", "\\" => "\\"
+        }.freeze
+        private_constant :ESCAPES
+
+        # When one of these delimiters is encountered, then the other
+        # one is allowed to be escaped as well.
+        DELIMITER_SYMETRY = { "[" => "]", "(" => ")", "{" => "}", "<" => ">" }.freeze
+        private_constant :DELIMITER_SYMETRY
+
+
+        # https://github.com/whitequark/parser/blob/v3.3.6.0/lib/parser/lexer-strings.rl#L14
+        REGEXP_META_CHARACTERS = ["\\", "$", "(", ")", "*", "+", ".", "<", ">", "?", "[", "]", "^", "{", "|", "}"]
+        private_constant :REGEXP_META_CHARACTERS
+
+        # Apply Ruby string escaping rules
+        def unescape_string(string, quote)
+          # In single-quoted heredocs, everything is taken literally.
+          return string if quote == "<<'"
+
+          # OPTIMIZATION: Assume that few strings need escaping to speed up the common case.
+          return string unless string.include?("\\")
+
+          # Enclosing character for the string. `"` for `"foo"`, `{` for `%w{foo}`, etc.
+          delimiter = quote[-1]
+
+          if regexp?(quote)
+            # Should be escaped handled to single-quoted heredocs. The only character that is
+            # allowed to be escaped is the delimiter, except when that also has special meaning
+            # in the regexp. Since all the symetry delimiters have special meaning, they don't need
+            # to be considered separately.
+            if REGEXP_META_CHARACTERS.include?(delimiter)
+              string
+            else
+              # There can never be an even amount of backslashes. It would be a syntax error.
+              string.gsub(/\\(#{Regexp.escape(delimiter)})/, '\1')
+            end
+          elsif interpolation?(quote)
+            # Appending individual escape sequences may force the string out of its intended
+            # encoding. Start out with binary and force it back later.
+            result = "".b
+
+            scanner = StringScanner.new(string)
+            while (skipped = scanner.skip_until(/\\/))
+              # Append what was just skipped over, excluding the found backslash.
+              result.append_as_bytes(string.byteslice(scanner.pos - skipped, skipped - 1))
+              escape_read(result, scanner, false, false)
+            end
+
+            # Add remaining chars
+            result.append_as_bytes(string.byteslice(scanner.pos..))
+            result.force_encoding(source_buffer.source.encoding)
+          else
+            delimiters = Regexp.escape("#{delimiter}#{DELIMITER_SYMETRY[delimiter]}")
+            string.gsub(/\\([\\#{delimiters}])/, '\1')
+          end
+        end
+
+        # Certain strings are merged into a single string token.
+        def simplify_string?(value, quote)
+          case quote
+          when "'"
+            # Only simplify 'foo'
+            !value.include?("\n")
+          when '"'
+            # Simplify when every line ends with a line continuation, or it is the last line
+            value.lines.all? do |line|
+              !line.end_with?("\n") || line[/(\\*)$/, 1]&.length&.odd?
+            end
+          else
+            # %q and similar are never simplified
+            false
+          end
+        end
+
+        # Escape a byte value, given the control and meta flags.
+        def escape_build(value, control, meta)
+          value &= 0x9f if control
+          value |= 0x80 if meta
+          value
+        end
+
+        # Read an escape out of the string scanner, given the control and meta
+        # flags, and push the unescaped value into the result.
+        def escape_read(result, scanner, control, meta)
+          if scanner.skip("\n")
+            # Line continuation
+          elsif (value = ESCAPES[scanner.peek(1)])
+            # Simple single-character escape sequences like \n
+            result.append_as_bytes(value)
+            scanner.pos += 1
+          elsif (value = scanner.scan(/[0-7]{1,3}/))
+            # \nnn
+            result.append_as_bytes(escape_build(value.to_i(8), control, meta))
+          elsif (value = scanner.scan(/x[0-9a-fA-F]{1,2}/))
+            # \xnn
+            result.append_as_bytes(escape_build(value[1..].to_i(16), control, meta))
+          elsif (value = scanner.scan(/u[0-9a-fA-F]{4}/))
+            # \unnnn
+            result.append_as_bytes(value[1..].hex.chr(Encoding::UTF_8))
+          elsif scanner.skip("u{}")
+            # https://github.com/whitequark/parser/issues/856
+          elsif (value = scanner.scan(/u{.*?}/))
+            # \u{nnnn ...}
+            value[2..-2].split.each do |unicode|
+              result.append_as_bytes(unicode.hex.chr(Encoding::UTF_8))
+            end
+          elsif (value = scanner.scan(/c\\?(?=[[:print:]])|C-\\?(?=[[:print:]])/))
+            # \cx or \C-x where x is an ASCII printable character
+            escape_read(result, scanner, true, meta)
+          elsif (value = scanner.scan(/M-\\?(?=[[:print:]])/))
+            # \M-x where x is an ASCII printable character
+            escape_read(result, scanner, control, true)
+          elsif (byte = scanner.scan_byte)
+            # Something else after an escape.
+            if control && byte == 0x3f # ASCII '?'
+              result.append_as_bytes(escape_build(0x7f, false, meta))
+            else
+              result.append_as_bytes(escape_build(byte, control, meta))
+            end
+          end
+        end
+
+        # In a percent array, certain whitespace can be preceeded with a backslash,
+        # causing the following characters to be part of the previous element.
+        def percent_array_unescape(string)
+          string.gsub(/(\\)+[ \f\n\r\t\v]/) do |full_match|
+            full_match.delete_prefix!("\\") if Regexp.last_match[1].length.odd?
+            full_match
+          end
+        end
+
+        # For %-arrays whitespace, the parser gem only considers whitespace before the newline.
+        def percent_array_leading_whitespace(string)
+          return 1 if string.start_with?("\n")
+
+          leading_whitespace = 0
+          string.each_char do |c|
+            break if c == "\n"
+            leading_whitespace += 1
+          end
+          leading_whitespace
+        end
+
+        # Determine if characters preceeded by a backslash should be escaped or not
+        def interpolation?(quote)
+          !quote.end_with?("'") && !quote.start_with?("%q", "%w", "%i", "%s")
+        end
+
+        # Regexp allow interpolation but are handled differently during unescaping
+        def regexp?(quote)
+          quote == "/" || quote.start_with?("%r")
+        end
+
+        # Determine if the string is part of a %-style array.
+        def percent_array?(quote)
+          quote.start_with?("%w", "%W", "%i", "%I")
+        end
+      end
+    end
+  end
+end
diff --git a/lib/prism/translation/parser_current.rb b/lib/prism/translation/parser_current.rb
new file mode 100644
index 0000000000..f7c1070e30
--- /dev/null
+++ b/lib/prism/translation/parser_current.rb
@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+# :markup: markdown
+#--
+# typed: ignore
+
+module Prism
+  module Translation
+    case RUBY_VERSION
+    when /^3\.3\./
+      ParserCurrent = Parser33
+    when /^3\.4\./
+      ParserCurrent = Parser34
+    when /^3\.5\./, /^4\.0\./
+      ParserCurrent = Parser40
+    when /^4\.1\./
+      ParserCurrent = Parser41
+    else
+      # Keep this in sync with released Ruby.
+      parser = Parser40
+      major, minor, _patch = Gem::Version.new(RUBY_VERSION).segments
+      warn "warning: `Prism::Translation::Current` is loading #{parser.name}, " \
+           "but you are running #{major}.#{minor}."
+      ParserCurrent = parser
+    end
+  end
+end
diff --git a/lib/prism/translation/parser_versions.rb b/lib/prism/translation/parser_versions.rb
new file mode 100644
index 0000000000..720c7d548c
--- /dev/null
+++ b/lib/prism/translation/parser_versions.rb
@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+# :markup: markdown
+
+module Prism
+  module Translation
+    # This class is the entry-point for Ruby 3.3 of `Prism::Translation::Parser`.
+    class Parser33 < Parser
+      def version # :nodoc:
+        33
+      end
+    end
+
+    # This class is the entry-point for Ruby 3.4 of `Prism::Translation::Parser`.
+    class Parser34 < Parser
+      def version # :nodoc:
+        34
+      end
+    end
+
+    # This class is the entry-point for Ruby 4.0 of `Prism::Translation::Parser`.
+    class Parser40 < Parser
+      def version # :nodoc:
+        40
+      end
+    end
+
+    Parser35 = Parser40 # :nodoc:
+
+    # This class is the entry-point for Ruby 4.1 of `Prism::Translation::Parser`.
+    class Parser41 < Parser
+      def version # :nodoc:
+        41
+      end
+    end
+  end
+end
diff --git a/lib/prism/translation/ripper.rb b/lib/prism/translation/ripper.rb
new file mode 100644
index 0000000000..f179a149a1
--- /dev/null
+++ b/lib/prism/translation/ripper.rb
@@ -0,0 +1,4266 @@
+# frozen_string_literal: true
+# :markup: markdown
+
+module Prism
+  module Translation
+    # This class provides a compatibility layer between prism and Ripper. It
+    # functions by parsing the entire tree first and then walking it and
+    # executing each of the Ripper callbacks as it goes. To use this class, you
+    # treat `Prism::Translation::Ripper` effectively as you would treat the
+    # `Ripper` class.
+    #
+    # Note that this class will serve the most common use cases, but Ripper's
+    # API is extensive and undocumented. It relies on reporting the state of the
+    # parser at any given time. We do our best to replicate that here, but
+    # because it is a different architecture it is not possible to perfectly
+    # replicate the behavior of Ripper.
+    #
+    # The main known difference is that we may omit dispatching some events in
+    # some cases. This impacts the following events:
+    #
+    # - on_assign_error
+    # - on_comma
+    # - on_ignored_nl
+    # - on_ignored_sp
+    # - on_nl
+    # - on_operator_ambiguous
+    # - on_semicolon
+    # - on_sp
+    #
+    class Ripper < Compiler
+      # Parses the given Ruby program read from +src+.
+      # +src+ must be a String or an IO or a object with a #gets method.
+      def self.parse(src, filename = "(ripper)", lineno = 1)
+        new(src, filename, lineno).parse
+      end
+
+      # Tokenizes the Ruby program and returns an array of an array,
+      # which is formatted like
+      # <code>[[lineno, column], type, token, state]</code>.
+      # The +filename+ argument is mostly ignored.
+      # By default, this method does not handle syntax errors in +src+,
+      # use the +raise_errors+ keyword to raise a SyntaxError for an error in +src+.
+      #
+      #     require "ripper"
+      #     require "pp"
+      #
+      #     pp Ripper.lex("def m(a) nil end")
+      #     #=> [[[1,  0], :on_kw,     "def", FNAME    ],
+      #          [[1,  3], :on_sp,     " ",   FNAME    ],
+      #          [[1,  4], :on_ident,  "m",   ENDFN    ],
+      #          [[1,  5], :on_lparen, "(",   BEG|LABEL],
+      #          [[1,  6], :on_ident,  "a",   ARG      ],
+      #          [[1,  7], :on_rparen, ")",   ENDFN    ],
+      #          [[1,  8], :on_sp,     " ",   BEG      ],
+      #          [[1,  9], :on_kw,     "nil", END      ],
+      #          [[1, 12], :on_sp,     " ",   END      ],
+      #          [[1, 13], :on_kw,     "end", END      ]]
+      #
+      def self.lex(src, filename = "-", lineno = 1, raise_errors: false)
+        coerced = coerce_source(src)
+        result = Prism.lex_compat(coerced, filepath: filename, line: lineno, version: "current", encoding: coerced.encoding)
+
+        if result.failure? && raise_errors
+          raise SyntaxError, result.errors.first.message
+        else
+          result.value
+        end
+      end
+
+      # Tokenizes the Ruby program and returns an array of strings.
+      # The +filename+ and +lineno+ arguments are mostly ignored, since the
+      # return value is just the tokenized input.
+      # By default, this method does not handle syntax errors in +src+,
+      # use the +raise_errors+ keyword to raise a SyntaxError for an error in +src+.
+      #
+      #   p Ripper.tokenize("def m(a) nil end")
+      #      # => ["def", " ", "m", "(", "a", ")", " ", "nil", " ", "end"]
+      #
+      def self.tokenize(...)
+        lex(...).map { |token| token[2] }
+      end
+
+      # Mirros the various lex_types that ripper supports
+      def self.coerce_source(source) # :nodoc:
+        if source.is_a?(IO)
+          source.read
+        elsif source.respond_to?(:gets)
+          src = +""
+          while line = source.gets
+            src << line
+          end
+          src
+        else
+          source.to_str
+        end
+      end
+
+      # This contains a table of all of the parser events and their
+      # corresponding arity.
+      PARSER_EVENT_TABLE = {
+        BEGIN: 1,
+        END: 1,
+        alias: 2,
+        alias_error: 2,
+        aref: 2,
+        aref_field: 2,
+        arg_ambiguous: 1,
+        arg_paren: 1,
+        args_add: 2,
+        args_add_block: 2,
+        args_add_star: 2,
+        args_forward: 0,
+        args_new: 0,
+        array: 1,
+        aryptn: 4,
+        assign: 2,
+        assign_error: 2,
+        assoc_new: 2,
+        assoc_splat: 1,
+        assoclist_from_args: 1,
+        bare_assoc_hash: 1,
+        begin: 1,
+        binary: 3,
+        block_var: 2,
+        blockarg: 1,
+        bodystmt: 4,
+        brace_block: 2,
+        break: 1,
+        call: 3,
+        case: 2,
+        class: 3,
+        class_name_error: 2,
+        command: 2,
+        command_call: 4,
+        const_path_field: 2,
+        const_path_ref: 2,
+        const_ref: 1,
+        def: 3,
+        defined: 1,
+        defs: 5,
+        do_block: 2,
+        dot2: 2,
+        dot3: 2,
+        dyna_symbol: 1,
+        else: 1,
+        elsif: 3,
+        ensure: 1,
+        excessed_comma: 0,
+        fcall: 1,
+        field: 3,
+        fndptn: 4,
+        for: 3,
+        hash: 1,
+        heredoc_dedent: 2,
+        hshptn: 3,
+        if: 3,
+        if_mod: 2,
+        ifop: 3,
+        in: 3,
+        kwrest_param: 1,
+        lambda: 2,
+        magic_comment: 2,
+        massign: 2,
+        method_add_arg: 2,
+        method_add_block: 2,
+        mlhs_add: 2,
+        mlhs_add_post: 2,
+        mlhs_add_star: 2,
+        mlhs_new: 0,
+        mlhs_paren: 1,
+        module: 2,
+        mrhs_add: 2,
+        mrhs_add_star: 2,
+        mrhs_new: 0,
+        mrhs_new_from_args: 1,
+        next: 1,
+        nokw_param: 1,
+        opassign: 3,
+        operator_ambiguous: 2,
+        param_error: 2,
+        params: 7,
+        paren: 1,
+        parse_error: 1,
+        program: 1,
+        qsymbols_add: 2,
+        qsymbols_new: 0,
+        qwords_add: 2,
+        qwords_new: 0,
+        redo: 0,
+        regexp_add: 2,
+        regexp_literal: 2,
+        regexp_new: 0,
+        rescue: 4,
+        rescue_mod: 2,
+        rest_param: 1,
+        retry: 0,
+        return: 1,
+        return0: 0,
+        sclass: 2,
+        stmts_add: 2,
+        stmts_new: 0,
+        string_add: 2,
+        string_concat: 2,
+        string_content: 0,
+        string_dvar: 1,
+        string_embexpr: 1,
+        string_literal: 1,
+        super: 1,
+        symbol: 1,
+        symbol_literal: 1,
+        symbols_add: 2,
+        symbols_new: 0,
+        top_const_field: 1,
+        top_const_ref: 1,
+        unary: 2,
+        undef: 1,
+        unless: 3,
+        unless_mod: 2,
+        until: 2,
+        until_mod: 2,
+        var_alias: 2,
+        var_field: 1,
+        var_ref: 1,
+        vcall: 1,
+        void_stmt: 0,
+        when: 3,
+        while: 2,
+        while_mod: 2,
+        word_add: 2,
+        word_new: 0,
+        words_add: 2,
+        words_new: 0,
+        xstring_add: 2,
+        xstring_literal: 1,
+        xstring_new: 0,
+        yield: 1,
+        yield0: 0,
+        zsuper: 0
+      }
+
+      # This contains a table of all of the scanner events and their
+      # corresponding arity.
+      SCANNER_EVENT_TABLE = {
+        CHAR: 1,
+        __end__: 1,
+        backref: 1,
+        backtick: 1,
+        comma: 1,
+        comment: 1,
+        const: 1,
+        cvar: 1,
+        embdoc: 1,
+        embdoc_beg: 1,
+        embdoc_end: 1,
+        embexpr_beg: 1,
+        embexpr_end: 1,
+        embvar: 1,
+        float: 1,
+        gvar: 1,
+        heredoc_beg: 1,
+        heredoc_end: 1,
+        ident: 1,
+        ignored_nl: 1,
+        imaginary: 1,
+        int: 1,
+        ivar: 1,
+        kw: 1,
+        label: 1,
+        label_end: 1,
+        lbrace: 1,
+        lbracket: 1,
+        lparen: 1,
+        nl: 1,
+        op: 1,
+        period: 1,
+        qsymbols_beg: 1,
+        qwords_beg: 1,
+        rational: 1,
+        rbrace: 1,
+        rbracket: 1,
+        regexp_beg: 1,
+        regexp_end: 1,
+        rparen: 1,
+        semicolon: 1,
+        sp: 1,
+        symbeg: 1,
+        symbols_beg: 1,
+        tlambda: 1,
+        tlambeg: 1,
+        tstring_beg: 1,
+        tstring_content: 1,
+        tstring_end: 1,
+        words_beg: 1,
+        words_sep: 1,
+        ignored_sp: 1
+      }
+
+      # This array contains name of parser events.
+      PARSER_EVENTS = PARSER_EVENT_TABLE.keys
+
+      # This array contains name of scanner events.
+      SCANNER_EVENTS = SCANNER_EVENT_TABLE.keys
+
+      # This array contains name of all ripper events.
+      EVENTS = PARSER_EVENTS + SCANNER_EVENTS
+
+      # A list of all of the Ruby keywords.
+      KEYWORDS = [
+        "alias",
+        "and",
+        "begin",
+        "BEGIN",
+        "break",
+        "case",
+        "class",
+        "def",
+        "defined?",
+        "do",
+        "else",
+        "elsif",
+        "end",
+        "END",
+        "ensure",
+        "false",
+        "for",
+        "if",
+        "in",
+        "module",
+        "next",
+        "nil",
+        "not",
+        "or",
+        "redo",
+        "rescue",
+        "retry",
+        "return",
+        "self",
+        "super",
+        "then",
+        "true",
+        "undef",
+        "unless",
+        "until",
+        "when",
+        "while",
+        "yield",
+        "__ENCODING__",
+        "__FILE__",
+        "__LINE__"
+      ].to_set
+
+      # A list of all of the Ruby binary operators.
+      BINARY_OPERATORS = [
+        :!=,
+        :!~,
+        :=~,
+        :==,
+        :===,
+        :<=>,
+        :>,
+        :>=,
+        :<,
+        :<=,
+        :&,
+        :|,
+        :^,
+        :>>,
+        :<<,
+        :-,
+        :+,
+        :%,
+        :/,
+        :*,
+        :**
+      ].to_set
+
+      private_constant :KEYWORDS, :BINARY_OPERATORS
+
+      # Parses +src+ and create S-exp tree.
+      # Returns more readable tree rather than Ripper.sexp_raw.
+      # This method is mainly for developer use.
+      # The +filename+ argument is mostly ignored.
+      # By default, this method does not handle syntax errors in +src+,
+      # returning +nil+ in such cases. Use the +raise_errors+ keyword
+      # to raise a SyntaxError for an error in +src+.
+      #
+      #     require "ripper"
+      #     require "pp"
+      #
+      #     pp Ripper.sexp("def m(a) nil end")
+      #       #=> [:program,
+      #            [[:def,
+      #             [:@ident, "m", [1, 4]],
+      #             [:paren, [:params, [[:@ident, "a", [1, 6]]], nil, nil, nil, nil, nil, nil]],
+      #             [:bodystmt, [[:var_ref, [:@kw, "nil", [1, 9]]]], nil, nil, nil]]]]
+      #
+      def self.sexp(src, filename = "-", lineno = 1, raise_errors: false)
+        builder = SexpBuilderPP.new(src, filename, lineno)
+        sexp = builder.parse
+        if builder.error?
+          if raise_errors
+            raise SyntaxError, builder.error
+          end
+        else
+          sexp
+        end
+      end
+
+      # Parses +src+ and create S-exp tree.
+      # This method is mainly for developer use.
+      # The +filename+ argument is mostly ignored.
+      # By default, this method does not handle syntax errors in +src+,
+      # returning +nil+ in such cases. Use the +raise_errors+ keyword
+      # to raise a SyntaxError for an error in +src+.
+      #
+      #     require "ripper"
+      #     require "pp"
+      #
+      #     pp Ripper.sexp_raw("def m(a) nil end")
+      #       #=> [:program,
+      #            [:stmts_add,
+      #             [:stmts_new],
+      #             [:def,
+      #              [:@ident, "m", [1, 4]],
+      #              [:paren, [:params, [[:@ident, "a", [1, 6]]], nil, nil, nil]],
+      #              [:bodystmt,
+      #               [:stmts_add, [:stmts_new], [:var_ref, [:@kw, "nil", [1, 9]]]],
+      #               nil,
+      #               nil,
+      #               nil]]]]
+      #
+      def self.sexp_raw(src, filename = "-", lineno = 1, raise_errors: false)
+        builder = SexpBuilder.new(src, filename, lineno)
+        sexp = builder.parse
+        if builder.error?
+          if raise_errors
+            raise SyntaxError, builder.error
+          end
+        else
+          sexp
+        end
+      end
+
+      autoload :Filter, "prism/translation/ripper/filter"
+      autoload :Lexer, "prism/translation/ripper/lexer"
+      autoload :SexpBuilder, "prism/translation/ripper/sexp"
+      autoload :SexpBuilderPP, "prism/translation/ripper/sexp"
+
+      # Provides optimized access to line and column information.
+      # Ripper bounds are mostly accessed in a linear fashion, so
+      # we can try a linear scan first and fall back to binary search.
+      class LineAndColumnCache # :nodoc:
+        # How many should it look ahead/behind before falling back to binary searching.
+        WINDOW = 8
+        private_constant :WINDOW
+
+        #: (Source source) -> void
+        def initialize(source)
+          @source = source
+          @offsets = source.offsets
+          @hint = 0
+        end
+
+        #: (Integer byte_offset) -> [Integer, Integer]
+        def line_and_column(byte_offset)
+          @hint = new_hint(byte_offset) || @source.find_line(byte_offset)
+          return [@hint + @source.start_line, byte_offset - @offsets[@hint]]
+        end
+
+        private
+
+        def new_hint(byte_offset)
+          if @offsets[@hint] <= byte_offset
+            # Same line?
+            if (@hint + 1 >= @offsets.size || @offsets[@hint + 1] > byte_offset)
+              return @hint
+            end
+
+            # Scan forwards
+            limit = [@hint + WINDOW + 1, @offsets.size].min
+            idx = @hint + 1
+            while idx < limit
+              if @offsets[idx] > byte_offset
+                return idx - 1
+              end
+              if @offsets[idx] == byte_offset
+                return idx
+              end
+              idx += 1
+            end
+          else
+            # Scan backwards
+            limit = @hint > WINDOW ? @hint - WINDOW : 0
+            idx = @hint
+            while idx >= limit + 1
+              if @offsets[idx - 1] <= byte_offset
+                return idx - 1
+              end
+              idx -= 1
+            end
+          end
+
+          nil
+        end
+      end
+
+      # :stopdoc:
+      # This is not part of the public API but used by some gems.
+
+      # Ripper-internal bitflags.
+      LEX_STATE_NAMES = %i[
+        BEG END ENDARG ENDFN ARG CMDARG MID FNAME DOT CLASS LABEL LABELED FITEM
+      ].map.with_index.to_h { |name, i| [2 ** i, name] }.freeze
+      private_constant :LEX_STATE_NAMES
+
+      LEX_STATE_NAMES.each do |value, key|
+        const_set("EXPR_#{key}", value)
+      end
+      EXPR_NONE = 0
+      EXPR_VALUE = EXPR_BEG
+      EXPR_BEG_ANY = EXPR_BEG | EXPR_MID | EXPR_CLASS
+      EXPR_ARG_ANY = EXPR_ARG | EXPR_CMDARG
+      EXPR_END_ANY = EXPR_END | EXPR_ENDARG | EXPR_ENDFN
+
+      def self.lex_state_name(state)
+        LEX_STATE_NAMES.filter_map { |flag, name| name if state & flag != 0  }.join("|")
+      end
+
+      # :startdoc:
+
+      # The source that is being parsed.
+      attr_reader :source
+
+      # The filename of the source being parsed.
+      attr_reader :filename
+
+      # The current line number of the parser.
+      attr_reader :lineno
+
+      # The current column in bytes of the parser.
+      attr_reader :column
+
+      # Create a new Translation::Ripper object with the given source.
+      def initialize(source, filename = "(ripper)", lineno = 1)
+        @source = Ripper.coerce_source(source)
+        @filename = filename
+        @lineno = lineno
+        @column = 0
+        @result = nil
+        @line_and_column_cache = nil
+      end
+
+      ##########################################################################
+      # Public interface
+      ##########################################################################
+
+      # True if the parser encountered an error during parsing.
+      def error?
+        result.failure?
+      end
+
+      # Parse the source and return the result.
+      def parse
+        result.comments.each do |comment|
+          location = comment.location
+          bounds(location)
+
+          if comment.is_a?(InlineComment)
+            # Inline comments always contain a newline if the line itself contains it
+            if result.source.source.bytesize > comment.location.end_offset
+              on_comment("#{comment.slice}\n")
+            else
+              on_comment(comment.slice)
+            end
+          else
+            offset = location.start_offset
+            lines = comment.slice.lines
+
+            lines.each_with_index do |line, index|
+              bounds(location.copy(start_offset: offset))
+
+              if index == 0
+                on_embdoc_beg(line)
+              elsif index == lines.size - 1
+                on_embdoc_end(line)
+              else
+                on_embdoc(line)
+              end
+
+              offset += line.bytesize
+            end
+          end
+        end
+
+        result.magic_comments.each do |magic_comment|
+          on_magic_comment(magic_comment.key, magic_comment.value)
+        end
+
+        unless result.data_loc.nil?
+          on___end__(result.data_loc.slice.each_line.first)
+        end
+
+        result.warnings.each do |warning|
+          bounds(warning.location)
+
+          if warning.level == :default
+            warning(warning.message)
+          else
+            case warning.type
+            when :ambiguous_first_argument_plus
+              on_arg_ambiguous("+")
+            when :ambiguous_first_argument_minus
+              on_arg_ambiguous("-")
+            when :ambiguous_slash
+              on_arg_ambiguous("/")
+            else
+              warn(warning.message)
+            end
+          end
+        end
+
+        if error?
+          result.errors.each do |error|
+            location = error.location
+            bounds(location)
+
+            case error.type
+            when :alias_argument
+              on_alias_error("can't make alias for the number variables", location.slice)
+            when :argument_formal_class
+              on_param_error("formal argument cannot be a class variable", location.slice)
+            when :argument_format_constant
+              on_param_error("formal argument cannot be a constant", location.slice)
+            when :argument_formal_global
+              on_param_error("formal argument cannot be a global variable", location.slice)
+            when :argument_formal_ivar
+              on_param_error("formal argument cannot be an instance variable", location.slice)
+            when :class_name, :module_name
+              on_class_name_error("class/module name must be CONSTANT", location.slice)
+            else
+              on_parse_error(error.message)
+            end
+          end
+
+          nil
+        else
+          result.value.accept(self)
+        end
+      end
+
+      ##########################################################################
+      # Visitor methods
+      ##########################################################################
+
+      # :stopdoc:
+
+      # alias foo bar
+      # ^^^^^^^^^^^^^
+      def visit_alias_method_node(node)
+        bounds(node.keyword_loc)
+        on_kw("alias")
+
+        new_name = visit(node.new_name)
+        old_name = visit(node.old_name)
+
+        bounds(node.location)
+        on_alias(new_name, old_name)
+      end
+
+      # alias $foo $bar
+      # ^^^^^^^^^^^^^^^
+      def visit_alias_global_variable_node(node)
+        bounds(node.keyword_loc)
+        on_kw("alias")
+
+        new_name = visit_alias_global_variable_node_value(node.new_name)
+        old_name = visit_alias_global_variable_node_value(node.old_name)
+
+        bounds(node.location)
+        on_var_alias(new_name, old_name)
+      end
+
+      # Visit one side of an alias global variable node.
+      private def visit_alias_global_variable_node_value(node)
+        bounds(node.location)
+
+        case node
+        when BackReferenceReadNode
+          on_backref(node.slice)
+        when GlobalVariableReadNode
+          on_gvar(node.name.to_s)
+        else
+          raise
+        end
+      end
+
+      # foo => bar | baz
+      #        ^^^^^^^^^
+      def visit_alternation_pattern_node(node)
+        left = visit_pattern_node(node.left)
+
+        bounds(node.operator_loc)
+        on_op("|")
+
+        right = visit_pattern_node(node.right)
+
+        bounds(node.location)
+        on_binary(left, :|, right)
+      end
+
+      # Visit a pattern within a pattern match. This is used to bypass the
+      # parenthesis node that can be used to wrap patterns.
+      private def visit_pattern_node(node)
+        if node.is_a?(ParenthesesNode)
+          bounds(node.opening_loc)
+          on_lparen("(")
+          result = visit(node.body)
+          bounds(node.closing_loc)
+          on_rparen(")")
+
+          result
+        else
+          visit(node)
+        end
+      end
+
+      # a and b
+      # ^^^^^^^
+      def visit_and_node(node)
+        left = visit(node.left)
+
+        bounds(node.operator_loc)
+        if node.operator == "and"
+          on_kw("and")
+        else
+          on_op("&&")
+        end
+
+        right = visit(node.right)
+
+        bounds(node.location)
+        on_binary(left, node.operator.to_sym, right)
+      end
+
+      # []
+      # ^^
+      def visit_array_node(node)
+        case (opening = node.opening)
+        when /^%w/
+          opening_loc = node.opening_loc
+          bounds(opening_loc)
+          on_qwords_beg(opening)
+
+          elements = on_qwords_new
+          previous = nil
+
+          node.elements.each do |element|
+            visit_words_sep(opening_loc, previous, element)
+
+            bounds(element.location)
+            elements = on_qwords_add(elements, on_tstring_content(element.content))
+
+            previous = element
+          end
+
+          visit_words_sep(opening_loc, node.elements.last, node.closing_loc)
+
+          bounds(node.closing_loc)
+          on_tstring_end(node.closing)
+        when /^%i/
+          opening_loc = node.opening_loc
+          bounds(opening_loc)
+          on_qsymbols_beg(opening)
+
+          elements = on_qsymbols_new
+          previous = nil
+
+          node.elements.each do |element|
+            visit_words_sep(opening_loc, previous, element)
+
+            bounds(element.location)
+            elements = on_qsymbols_add(elements, on_tstring_content(element.value))
+
+            previous = element
+          end
+
+          visit_words_sep(opening_loc, node.elements.last, node.closing_loc)
+
+          bounds(node.closing_loc)
+          on_tstring_end(node.closing)
+        when /^%W/
+          opening_loc = node.opening_loc
+          bounds(opening_loc)
+          on_words_beg(opening)
+
+          elements = on_words_new
+          previous = nil
+
+          node.elements.each do |element|
+            visit_words_sep(opening_loc, previous, element)
+
+            bounds(element.location)
+            elements =
+              on_words_add(
+                elements,
+                if element.is_a?(StringNode)
+                  on_word_add(on_word_new, on_tstring_content(element.content))
+                else
+                  element.parts.inject(on_word_new) do |word, part|
+                    word_part =
+                      if part.is_a?(StringNode)
+                        bounds(part.location)
+                        on_tstring_content(part.content)
+                      else
+                        visit(part)
+                      end
+
+                    on_word_add(word, word_part)
+                  end
+                end
+              )
+
+            previous = element
+          end
+
+          visit_words_sep(opening_loc, node.elements.last, node.closing_loc)
+
+          bounds(node.closing_loc)
+          on_tstring_end(node.closing)
+        when /^%I/
+          opening_loc = node.opening_loc
+          bounds(opening_loc)
+          on_symbols_beg(opening)
+
+          elements = on_symbols_new
+          previous = nil
+
+          node.elements.each do |element|
+            visit_words_sep(opening_loc, previous, element)
+
+            bounds(element.location)
+            elements =
+              on_symbols_add(
+                elements,
+                if element.is_a?(SymbolNode)
+                  on_word_add(on_word_new, on_tstring_content(element.value))
+                else
+                  element.parts.inject(on_word_new) do |word, part|
+                    word_part =
+                      if part.is_a?(StringNode)
+                        bounds(part.location)
+                        on_tstring_content(part.content)
+                      else
+                        visit(part)
+                      end
+
+                    on_word_add(word, word_part)
+                  end
+                end
+              )
+
+            previous = element
+          end
+
+          visit_words_sep(opening_loc, node.elements.last, node.closing_loc)
+
+          bounds(node.closing_loc)
+          on_tstring_end(node.closing)
+        else
+          bounds(node.opening_loc)
+          on_lbracket(opening)
+
+          elements = visit_arguments(node.elements) unless node.elements.empty?
+
+          bounds(node.closing_loc)
+          on_rbracket(node.closing)
+        end
+
+        bounds(node.location)
+        on_array(elements)
+      end
+
+      # Dispatch words_sep events that contains the whitespace between the elements
+      # of list literals.
+      private def visit_words_sep(opening_loc, previous, current)
+        start_offset = (previous.nil? ? opening_loc : previous.location).end_offset
+        end_offset = current.start_offset
+        length = end_offset - start_offset
+
+        if length > 0
+          whitespace = source.byteslice(start_offset, length)
+          current_offset = start_offset
+          whitespace.each_line do |part|
+            bounds(opening_loc.copy(start_offset: current_offset, length: part.bytesize))
+            on_words_sep(part)
+            current_offset += part.bytesize
+          end
+        end
+      end
+
+      # Visit a list of elements, like the elements of an array or arguments.
+      private def visit_arguments(elements)
+        bounds(elements.first.location)
+        elements.inject(on_args_new) do |args, element|
+          arg = visit(element)
+          bounds(element.location)
+
+          case element
+          when BlockArgumentNode
+            on_args_add_block(args, arg)
+          when SplatNode
+            on_args_add_star(args, arg)
+          else
+            on_args_add(args, arg)
+          end
+        end
+      end
+
+      # foo => [bar]
+      #        ^^^^^
+      def visit_array_pattern_node(node)
+        constant = visit(node.constant)
+
+        if node.opening_loc
+          bounds(node.opening_loc)
+          node.opening == "[" ? on_lbracket("[") : on_lparen("(")
+        end
+
+        requireds = visit_all(node.requireds) if node.requireds.any?
+        rest =
+          if (rest_node = node.rest).is_a?(SplatNode)
+            bounds(rest_node.operator_loc)
+            on_op("*")
+
+            if rest_node.expression.nil?
+              bounds(rest_node.location)
+              on_var_field(nil)
+            else
+              visit(rest_node.expression)
+            end
+          end
+
+        posts = visit_all(node.posts) if node.posts.any?
+
+        if node.closing_loc
+          bounds(node.closing_loc)
+          node.closing == "]" ? on_rbracket("]") : on_rparen(")")
+        end
+        bounds(node.location)
+        on_aryptn(constant, requireds, rest, posts)
+      end
+
+      # foo(bar)
+      #     ^^^
+      def visit_arguments_node(node)
+        arguments, _ = visit_call_node_arguments(node, nil, false)
+        arguments
+      end
+
+      # { a: 1 }
+      #   ^^^^
+      def visit_assoc_node(node)
+        key = visit(node.key)
+
+        if node.operator_loc
+          bounds(node.operator_loc)
+          on_op("=>")
+        end
+
+        value = visit(node.value)
+
+        bounds(node.location)
+        on_assoc_new(key, value)
+      end
+
+      # def foo(**); bar(**); end
+      #                  ^^
+      #
+      # { **foo }
+      #   ^^^^^
+      def visit_assoc_splat_node(node)
+        bounds(node.operator_loc)
+        on_op("**")
+
+        value = visit(node.value)
+
+        bounds(node.location)
+        on_assoc_splat(value)
+      end
+
+      # $+
+      # ^^
+      def visit_back_reference_read_node(node)
+        bounds(node.location)
+        on_backref(node.slice)
+      end
+
+      # begin end
+      # ^^^^^^^^^
+      def visit_begin_node(node)
+        if node.begin_keyword_loc
+          bounds(node.begin_keyword_loc)
+          on_kw("begin")
+        end
+
+        clauses = visit_begin_node_clauses(node.begin_keyword_loc, node, false)
+
+        if node.end_keyword_loc
+          bounds(node.end_keyword_loc)
+          on_kw("end")
+        end
+
+        bounds(node.location)
+        on_begin(clauses)
+      end
+
+      # Visit the clauses of a begin node to form an on_bodystmt call.
+      private def visit_begin_node_clauses(location, node, allow_newline)
+        statements =
+          if node.statements.nil?
+            on_stmts_add(on_stmts_new, on_void_stmt)
+          else
+            body = node.statements.body
+            body = [nil, *body] if void_stmt?(location, node.statements.body[0].location, allow_newline)
+
+            bounds(node.statements.location)
+            visit_statements_node_body(body)
+          end
+
+        rescue_clause = visit(node.rescue_clause)
+        else_clause =
+          unless (else_clause_node = node.else_clause).nil?
+            bounds(else_clause_node.else_keyword_loc)
+            on_kw("else")
+
+            else_statements =
+              if else_clause_node.statements.nil?
+                [nil]
+              else
+                body = else_clause_node.statements.body
+                body = [nil, *body] if void_stmt?(else_clause_node.else_keyword_loc, else_clause_node.statements.body[0].location, allow_newline)
+                body
+              end
+
+            bounds(else_clause_node.location)
+            visit_statements_node_body(else_statements)
+          end
+        ensure_clause = visit(node.ensure_clause)
+
+        bounds(node.location)
+        on_bodystmt(statements, rescue_clause, else_clause, ensure_clause)
+      end
+
+      # Visit the body of a structure that can have either a set of statements
+      # or statements wrapped in rescue/else/ensure.
+      private def visit_body_node(location, node, allow_newline = false)
+        case node
+        when nil
+          bounds(location)
+          on_bodystmt(visit_statements_node_body([nil]), nil, nil, nil)
+        when StatementsNode
+          body = [*node.body]
+          body = [nil, *body] if void_stmt?(location, body[0].location, allow_newline)
+          stmts = visit_statements_node_body(body)
+
+          bounds(node.body.first.location)
+          on_bodystmt(stmts, nil, nil, nil)
+        when BeginNode
+          visit_begin_node_clauses(location, node, allow_newline)
+        else
+          raise
+        end
+      end
+
+      # foo(&bar)
+      #     ^^^^
+      def visit_block_argument_node(node)
+        bounds(node.operator_loc)
+        on_op("&")
+        visit(node.expression)
+      end
+
+      # foo { |; bar| }
+      #          ^^^
+      def visit_block_local_variable_node(node)
+        bounds(node.location)
+        on_ident(node.name.to_s)
+      end
+
+      # Visit a BlockNode.
+      def visit_block_node(node)
+        braces = node.opening == "{"
+        bounds(node.opening_loc)
+        if braces
+          on_lbrace("{")
+        else
+          on_kw("do")
+        end
+
+        parameters = visit(node.parameters)
+
+        body =
+          case node.body
+          when nil
+            bounds(node.location)
+            stmts = on_stmts_add(on_stmts_new, on_void_stmt)
+
+            bounds(node.location)
+            braces ? stmts : on_bodystmt(stmts, nil, nil, nil)
+          when StatementsNode
+            stmts = node.body.body
+            stmts = [nil, *stmts] if void_stmt?(node.parameters&.location || node.opening_loc, node.body.location, false)
+            stmts = visit_statements_node_body(stmts)
+
+            bounds(node.body.location)
+            braces ? stmts : on_bodystmt(stmts, nil, nil, nil)
+          when BeginNode
+            visit_body_node(node.parameters&.location || node.opening_loc, node.body)
+          else
+            raise
+          end
+
+        if braces
+          bounds(node.closing_loc)
+          on_rbrace("}")
+        else
+          bounds(node.closing_loc)
+          on_kw("end")
+        end
+
+        if braces
+          bounds(node.location)
+          on_brace_block(parameters, body)
+        else
+          bounds(node.location)
+          on_do_block(parameters, body)
+        end
+      end
+
+      # def foo(&bar); end
+      #         ^^^^
+      def visit_block_parameter_node(node)
+        bounds(node.operator_loc)
+        on_op("&")
+
+        if node.name_loc.nil?
+          bounds(node.location)
+          on_blockarg(nil)
+        else
+          bounds(node.name_loc)
+          name = on_ident(node.name.to_s)
+
+          bounds(node.location)
+          on_blockarg(name)
+        end
+      end
+
+      # A block's parameters.
+      def visit_block_parameters_node(node)
+        bounds(node.opening_loc)
+        on_op("|")
+
+        parameters =
+          if node.parameters.nil?
+            on_params(nil, nil, nil, nil, nil, nil, nil)
+          else
+            visit(node.parameters)
+          end
+
+        locals =
+          if node.locals.any?
+            visit_all(node.locals)
+          else
+            false
+          end
+
+        bounds(node.closing_loc)
+        on_op("|")
+
+        bounds(node.location)
+        on_block_var(parameters, locals)
+      end
+
+      # break
+      # ^^^^^
+      #
+      # break foo
+      # ^^^^^^^^^
+      def visit_break_node(node)
+        bounds(node.keyword_loc)
+        on_kw("break")
+
+        if node.arguments.nil?
+          bounds(node.location)
+          on_break(on_args_new)
+        else
+          arguments = visit(node.arguments)
+
+          bounds(node.location)
+          on_break(arguments)
+        end
+      end
+
+      # foo
+      # ^^^
+      #
+      # foo.bar
+      # ^^^^^^^
+      #
+      # foo.bar() {}
+      # ^^^^^^^^^^^^
+      def visit_call_node(node)
+        if node.call_operator_loc.nil?
+          case node.name
+          when :[]
+            receiver = visit(node.receiver)
+
+            bounds(node.opening_loc)
+            on_lbracket("[")
+
+            arguments, block_node = visit_call_node_arguments(node.arguments, node.block, trailing_comma?(node.arguments&.location || node.location, node.closing_loc))
+
+            bounds(node.closing_loc)
+            on_rbracket("]")
+
+            block = visit(block_node)
+
+            bounds(node.location)
+            call = on_aref(receiver, arguments)
+
+            if block_node
+              bounds(node.location)
+              on_method_add_block(call, block)
+            else
+              call
+            end
+          when :[]=
+            receiver = visit(node.receiver)
+
+            bounds(node.opening_loc)
+            on_lbracket("[")
+
+            *arguments, last_argument = node.arguments.arguments
+            arguments << node.block if !node.block.nil?
+
+            arguments =
+              if arguments.any?
+                args = visit_arguments(arguments)
+
+                if !node.block.nil?
+                  args
+                else
+                  bounds(arguments.first.location)
+                  on_args_add_block(args, false)
+                end
+              end
+
+            bounds(node.closing_loc)
+            on_rbracket("]")
+            bounds(node.equal_loc)
+            on_op("=")
+
+            bounds(node.location)
+            call = on_aref_field(receiver, arguments)
+            value = visit_write_value(last_argument)
+
+            bounds(last_argument.location)
+            on_assign(call, value)
+          when :-@, :+@, :~
+            bounds(node.message_loc)
+            on_op(node.message)
+
+            receiver = visit(node.receiver)
+            bounds(node.location)
+            on_unary(node.name, receiver)
+          when :!
+            bounds(node.message_loc)
+            if node.message == "not"
+              on_kw("not")
+
+              if node.opening_loc
+                bounds(node.opening_loc)
+                on_lparen("(")
+              end
+
+              receiver =
+                if node.receiver.is_a?(ParenthesesNode) && node.receiver.body.nil?
+                  # The parens in `not()` just emit parens and nothing else.
+                  bounds(node.receiver.opening_loc)
+                  on_lparen("(")
+                  bounds(node.receiver.closing_loc)
+                  on_rparen(")")
+                  nil
+                else
+                  visit(node.receiver)
+                end
+
+              if node.closing_loc
+                bounds(node.closing_loc)
+                on_rparen(")")
+              end
+              bounds(node.location)
+              on_unary(:not, receiver)
+            else
+              on_op("!")
+
+              receiver = visit(node.receiver)
+
+              bounds(node.location)
+              on_unary(:!, receiver)
+            end
+          when BINARY_OPERATORS
+            receiver = visit(node.receiver)
+
+            bounds(node.message_loc)
+            on_op(node.message)
+
+            value = visit(node.arguments.arguments.first)
+
+            bounds(node.location)
+            on_binary(receiver, node.name, value)
+          else
+            bounds(node.message_loc)
+            message = visit_token(node.message, false)
+
+            if node.variable_call?
+              on_vcall(message)
+            else
+              if node.opening_loc
+                bounds(node.opening_loc)
+                on_lparen("(")
+              end
+
+              arguments, block_node = visit_call_node_arguments(node.arguments, node.block, trailing_comma?(node.arguments&.location || node.location, node.closing_loc || node.location))
+
+              if node.closing_loc
+                bounds(node.closing_loc)
+                on_rparen(")")
+              end
+
+              block = visit(block_node)
+              call =
+                if node.opening_loc.nil? && get_arguments_and_block(node.arguments, node.block).first.any?
+                  bounds(node.location)
+                  on_command(message, arguments)
+                elsif !node.opening_loc.nil?
+                  bounds(node.location)
+                  on_method_add_arg(on_fcall(message), on_arg_paren(arguments))
+                else
+                  bounds(node.location)
+                  on_method_add_arg(on_fcall(message), on_args_new)
+                end
+
+              if block_node
+                bounds(node.block.location)
+                on_method_add_block(call, block)
+              else
+                call
+              end
+            end
+          end
+        else
+          receiver = visit(node.receiver)
+
+          bounds(node.call_operator_loc)
+          call_operator = visit_call_operator(node.call_operator)
+
+          message =
+            if node.message_loc.nil?
+              :call
+            else
+              bounds(node.message_loc)
+              visit_token(node.message, false)
+            end
+
+          if node.equal_loc
+            bounds(node.equal_loc)
+            on_op("=")
+          end
+
+          if node.name.end_with?("=") && !node.message.end_with?("=") && !node.arguments.nil? && node.block.nil?
+            value = visit_write_value(node.arguments.arguments.first)
+
+            bounds(node.location)
+            on_assign(on_field(receiver, call_operator, message), value)
+          else
+            if node.opening_loc
+              bounds(node.opening_loc)
+              on_lparen("(")
+            end
+
+            arguments, block_node = visit_call_node_arguments(node.arguments, node.block, trailing_comma?(node.arguments&.location || node.location, node.closing_loc || node.location))
+
+            if node.closing_loc
+              bounds(node.closing_loc)
+              on_rparen(")")
+            end
+
+            block = visit(block_node)
+            call =
+              if node.opening_loc.nil?
+                bounds(node.location)
+
+                if node.arguments.nil? && !node.block.is_a?(BlockArgumentNode)
+                  on_call(receiver, call_operator, message)
+                else
+                  on_command_call(receiver, call_operator, message, arguments)
+                end
+              else
+                bounds(node.opening_loc)
+                arguments = on_arg_paren(arguments)
+
+                bounds(node.location)
+                on_method_add_arg(on_call(receiver, call_operator, message), arguments)
+              end
+
+            if block_node
+              bounds(node.block.location)
+              on_method_add_block(call, block)
+            else
+              call
+            end
+          end
+        end
+      end
+
+      # Extract the arguments and block Ripper-style, which means if the block
+      # is like `&b` then it's moved to arguments.
+      private def get_arguments_and_block(arguments_node, block_node)
+        arguments = arguments_node&.arguments || []
+        block = block_node
+
+        if block.is_a?(BlockArgumentNode)
+          arguments += [block]
+          block = nil
+        end
+
+        [arguments, block]
+      end
+
+      # Visit the arguments and block of a call node and return the arguments
+      # and block as they should be used.
+      private def visit_call_node_arguments(arguments_node, block_node, trailing_comma)
+        arguments, block = get_arguments_and_block(arguments_node, block_node)
+
+        [
+          if arguments.length == 1 && arguments.first.is_a?(ForwardingArgumentsNode)
+            visit(arguments.first)
+          elsif arguments.any?
+            args = visit_arguments(arguments)
+
+            if block_node.is_a?(BlockArgumentNode) || arguments.last.is_a?(ForwardingArgumentsNode) || command?(arguments.last) || trailing_comma
+              args
+            else
+              bounds(arguments.first.location)
+              on_args_add_block(args, false)
+            end
+          end,
+          block,
+        ]
+      end
+
+      # Returns true if the given node is a command node.
+      private def command?(node)
+        node.is_a?(CallNode) &&
+          node.opening_loc.nil? &&
+          (!node.arguments.nil? || node.block.is_a?(BlockArgumentNode)) &&
+          !BINARY_OPERATORS.include?(node.name)
+      end
+
+      # foo.bar += baz
+      # ^^^^^^^^^^^^^^^
+      def visit_call_operator_write_node(node)
+        receiver = visit(node.receiver)
+
+        bounds(node.call_operator_loc)
+        call_operator = visit_call_operator(node.call_operator)
+
+        bounds(node.message_loc)
+        message = visit_token(node.message)
+
+        bounds(node.location)
+        target = on_field(receiver, call_operator, message)
+
+        bounds(node.binary_operator_loc)
+        operator = on_op("#{node.binary_operator}=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # foo.bar &&= baz
+      # ^^^^^^^^^^^^^^^
+      def visit_call_and_write_node(node)
+        receiver = visit(node.receiver)
+
+        bounds(node.call_operator_loc)
+        call_operator = visit_call_operator(node.call_operator)
+
+        bounds(node.message_loc)
+        message = visit_token(node.message)
+
+        bounds(node.location)
+        target = on_field(receiver, call_operator, message)
+
+        bounds(node.operator_loc)
+        operator = on_op("&&=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # foo.bar ||= baz
+      # ^^^^^^^^^^^^^^^
+      def visit_call_or_write_node(node)
+        receiver = visit(node.receiver)
+
+        bounds(node.call_operator_loc)
+        call_operator = visit_call_operator(node.call_operator)
+
+        bounds(node.message_loc)
+        message = visit_token(node.message)
+
+        bounds(node.location)
+        target = on_field(receiver, call_operator, message)
+
+        bounds(node.operator_loc)
+        operator = on_op("||=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # foo.bar, = 1
+      # ^^^^^^^
+      def visit_call_target_node(node)
+        if node.call_operator == "::"
+          receiver = visit(node.receiver)
+
+          bounds(node.call_operator_loc)
+          on_op("::")
+
+          bounds(node.message_loc)
+          message = visit_token(node.message)
+
+          bounds(node.location)
+          on_const_path_field(receiver, message)
+        else
+          receiver = visit(node.receiver)
+
+          bounds(node.call_operator_loc)
+          call_operator = visit_call_operator(node.call_operator)
+
+          bounds(node.message_loc)
+          message = visit_token(node.message)
+
+          bounds(node.location)
+          on_field(receiver, call_operator, message)
+        end
+      end
+
+      # foo => bar => baz
+      #        ^^^^^^^^^^
+      def visit_capture_pattern_node(node)
+        value = visit(node.value)
+
+        bounds(node.operator_loc)
+        on_op("=>")
+
+        target = visit(node.target)
+
+        bounds(node.location)
+        on_binary(value, :"=>", target)
+      end
+
+      # case foo; when bar; end
+      # ^^^^^^^^^^^^^^^^^^^^^^^
+      def visit_case_node(node)
+        bounds(node.case_keyword_loc)
+        on_kw("case")
+
+        predicate = visit(node.predicate)
+        visited_conditions = node.conditions.map { |condition| visit(condition) }
+        visited_else_clause = visit(node.else_clause)
+
+        if !node.else_clause
+          bounds(node.end_keyword_loc)
+          on_kw("end")
+        end
+
+        clauses =
+          visited_conditions.reverse_each.inject(visited_else_clause) do |current, condition|
+            on_when(*condition, current)
+          end
+
+        bounds(node.location)
+        on_case(predicate, clauses)
+      end
+
+      # case foo; in bar; end
+      # ^^^^^^^^^^^^^^^^^^^^^
+      def visit_case_match_node(node)
+        bounds(node.case_keyword_loc)
+        on_kw("case")
+
+        predicate = visit(node.predicate)
+        visited_conditions = node.conditions.map do | condition|
+          visit(condition)
+        end
+        visited_else_clause = visit(node.else_clause)
+
+        if !node.else_clause
+          bounds(node.end_keyword_loc)
+          on_kw("end")
+        end
+
+        clauses =
+          visited_conditions.reverse_each.inject(visited_else_clause) do |current, condition|
+            on_in(*condition, current)
+          end
+
+        bounds(node.location)
+        on_case(predicate, clauses)
+      end
+
+      # class Foo; end
+      # ^^^^^^^^^^^^^^
+      def visit_class_node(node)
+        bounds(node.class_keyword_loc)
+        on_kw("class")
+
+        constant_path =
+          if node.constant_path.is_a?(ConstantReadNode)
+            bounds(node.constant_path.location)
+            on_const_ref(on_const(node.constant_path.name.to_s))
+          else
+            visit(node.constant_path)
+          end
+
+        if node.inheritance_operator_loc
+          bounds(node.inheritance_operator_loc)
+          on_op("<")
+        end
+
+        superclass = visit(node.superclass)
+        bodystmt = visit_body_node(node.superclass&.location || node.constant_path.location, node.body, node.superclass.nil?)
+
+        bounds(node.end_keyword_loc)
+        on_kw("end")
+
+        bounds(node.location)
+        on_class(constant_path, superclass, bodystmt)
+      end
+
+      # @@foo
+      # ^^^^^
+      def visit_class_variable_read_node(node)
+        bounds(node.location)
+        on_var_ref(on_cvar(node.slice))
+      end
+
+      # @@foo = 1
+      # ^^^^^^^^^
+      def visit_class_variable_write_node(node)
+        bounds(node.name_loc)
+        target = on_var_field(on_cvar(node.name.to_s))
+
+        bounds(node.operator_loc)
+        on_op("=")
+
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_assign(target, value)
+      end
+
+      # @@foo += bar
+      # ^^^^^^^^^^^^
+      def visit_class_variable_operator_write_node(node)
+        bounds(node.name_loc)
+        target = on_var_field(on_cvar(node.name.to_s))
+
+        bounds(node.binary_operator_loc)
+        operator = on_op("#{node.binary_operator}=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # @@foo &&= bar
+      # ^^^^^^^^^^^^^
+      def visit_class_variable_and_write_node(node)
+        bounds(node.name_loc)
+        target = on_var_field(on_cvar(node.name.to_s))
+
+        bounds(node.operator_loc)
+        operator = on_op("&&=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # @@foo ||= bar
+      # ^^^^^^^^^^^^^
+      def visit_class_variable_or_write_node(node)
+        bounds(node.name_loc)
+        target = on_var_field(on_cvar(node.name.to_s))
+
+        bounds(node.operator_loc)
+        operator = on_op("||=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # @@foo, = bar
+      # ^^^^^
+      def visit_class_variable_target_node(node)
+        bounds(node.location)
+        on_var_field(on_cvar(node.name.to_s))
+      end
+
+      # Foo
+      # ^^^
+      def visit_constant_read_node(node)
+        bounds(node.location)
+        on_var_ref(on_const(node.name.to_s))
+      end
+
+      # Foo = 1
+      # ^^^^^^^
+      def visit_constant_write_node(node)
+        bounds(node.name_loc)
+        target = on_var_field(on_const(node.name.to_s))
+
+        bounds(node.operator_loc)
+        on_op("=")
+
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_assign(target, value)
+      end
+
+      # Foo += bar
+      # ^^^^^^^^^^^
+      def visit_constant_operator_write_node(node)
+        bounds(node.name_loc)
+        target = on_var_field(on_const(node.name.to_s))
+
+        bounds(node.binary_operator_loc)
+        operator = on_op("#{node.binary_operator}=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # Foo &&= bar
+      # ^^^^^^^^^^^^
+      def visit_constant_and_write_node(node)
+        bounds(node.name_loc)
+        target = on_var_field(on_const(node.name.to_s))
+
+        bounds(node.operator_loc)
+        operator = on_op("&&=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # Foo ||= bar
+      # ^^^^^^^^^^^^
+      def visit_constant_or_write_node(node)
+        bounds(node.name_loc)
+        target = on_var_field(on_const(node.name.to_s))
+
+        bounds(node.operator_loc)
+        operator = on_op("||=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # Foo, = bar
+      # ^^^
+      def visit_constant_target_node(node)
+        bounds(node.location)
+        on_var_field(on_const(node.name.to_s))
+      end
+
+      # Foo::Bar
+      # ^^^^^^^^
+      def visit_constant_path_node(node)
+        if node.parent.nil?
+          if node.delimiter_loc
+            bounds(node.delimiter_loc)
+            on_op("::")
+          end
+
+          bounds(node.name_loc)
+          child = on_const(node.name.to_s)
+
+          bounds(node.location)
+          on_top_const_ref(child)
+        else
+          parent = visit(node.parent)
+
+          bounds(node.delimiter_loc)
+          on_op("::")
+
+          bounds(node.name_loc)
+          child = on_const(node.name.to_s)
+
+          bounds(node.location)
+          on_const_path_ref(parent, child)
+        end
+      end
+
+      # Foo::Bar = 1
+      # ^^^^^^^^^^^^
+      def visit_constant_path_write_node(node)
+        target = visit_constant_path_write_node_target(node.target)
+
+        bounds(node.operator_loc)
+        on_op("=")
+
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_assign(target, value)
+      end
+
+      # Visit a constant path that is part of a write node.
+      private def visit_constant_path_write_node_target(node)
+        if node.parent.nil?
+          if node.delimiter_loc
+            bounds(node.delimiter_loc)
+            on_op("::")
+          end
+
+          bounds(node.name_loc)
+          child = on_const(node.name.to_s)
+
+          bounds(node.location)
+          on_top_const_field(child)
+        else
+          parent = visit(node.parent)
+
+          bounds(node.delimiter_loc)
+          on_op("::")
+
+          bounds(node.name_loc)
+          child = on_const(node.name.to_s)
+
+          bounds(node.location)
+          on_const_path_field(parent, child)
+        end
+      end
+
+      # Foo::Bar += baz
+      # ^^^^^^^^^^^^^^^
+      def visit_constant_path_operator_write_node(node)
+        target = visit_constant_path_write_node_target(node.target)
+
+        bounds(node.binary_operator_loc)
+        operator = on_op("#{node.binary_operator}=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # Foo::Bar &&= baz
+      # ^^^^^^^^^^^^^^^^
+      def visit_constant_path_and_write_node(node)
+        target = visit_constant_path_write_node_target(node.target)
+
+        bounds(node.operator_loc)
+        operator = on_op("&&=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # Foo::Bar ||= baz
+      # ^^^^^^^^^^^^^^^^
+      def visit_constant_path_or_write_node(node)
+        target = visit_constant_path_write_node_target(node.target)
+
+        bounds(node.operator_loc)
+        operator = on_op("||=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # Foo::Bar, = baz
+      # ^^^^^^^^
+      def visit_constant_path_target_node(node)
+        visit_constant_path_write_node_target(node)
+      end
+
+      # def foo; end
+      # ^^^^^^^^^^^^
+      #
+      # def self.foo; end
+      # ^^^^^^^^^^^^^^^^^
+      def visit_def_node(node)
+        bounds(node.def_keyword_loc)
+        on_kw("def")
+
+        receiver = visit(node.receiver)
+        operator =
+          if !node.operator_loc.nil?
+            bounds(node.operator_loc)
+            node.operator == "." ? on_period(".") : on_op("::")
+          end
+
+        bounds(node.name_loc)
+        name = visit_token(node.name_loc.slice)
+
+        if node.lparen_loc
+          bounds(node.lparen_loc)
+          on_lparen("(")
+        end
+
+        parameters =
+          if node.parameters.nil?
+            bounds(node.location)
+            on_params(nil, nil, nil, nil, nil, nil, nil)
+          else
+            visit(node.parameters)
+          end
+
+        if !node.lparen_loc.nil?
+          bounds(node.rparen_loc)
+          on_rparen(")")
+          bounds(node.lparen_loc)
+          parameters = on_paren(parameters)
+        end
+
+        if node.equal_loc
+          bounds(node.equal_loc)
+          on_op("=")
+        end
+
+        bodystmt =
+          if node.equal_loc.nil?
+            visit_body_node(node.rparen_loc || node.end_keyword_loc, node.body)
+          else
+            body = visit(node.body.body.first)
+
+            bounds(node.body.location)
+            on_bodystmt(body, nil, nil, nil)
+          end
+
+        if node.end_keyword_loc
+          bounds(node.end_keyword_loc)
+          on_kw("end")
+        end
+
+        bounds(node.location)
+        if receiver
+          on_defs(receiver, operator, name, parameters, bodystmt)
+        else
+          on_def(name, parameters, bodystmt)
+        end
+      end
+
+      # defined? a
+      # ^^^^^^^^^^
+      #
+      # defined?(a)
+      # ^^^^^^^^^^^
+      def visit_defined_node(node)
+        bounds(node.keyword_loc)
+        on_kw("defined?")
+
+        if node.lparen_loc
+          bounds(node.lparen_loc)
+          on_lparen("(")
+        end
+
+        expression = visit(node.value)
+
+        if node.rparen_loc
+          bounds(node.rparen_loc)
+          on_rparen(")")
+        end
+
+        # Very weird circumstances here where something like:
+        #
+        #     defined?
+        #     (1)
+        #
+        # gets parsed in Ruby as having only the `1` expression but in Ripper it
+        # gets parsed as having a parentheses node. In this case we need to
+        # synthesize that node to match Ripper's behavior.
+        if node.lparen_loc && node.keyword_loc.join(node.lparen_loc).slice.include?("\n")
+          bounds(node.lparen_loc.join(node.rparen_loc))
+          expression = on_paren(on_stmts_add(on_stmts_new, expression))
+        end
+
+        bounds(node.location)
+        on_defined(expression)
+      end
+
+      # if foo then bar else baz end
+      #                 ^^^^^^^^^^^^
+      def visit_else_node(node)
+        bounds(node.else_keyword_loc)
+        on_kw("else")
+
+        statements =
+          if node.statements.nil?
+            [nil]
+          else
+            body = node.statements.body
+            body = [nil, *body] if void_stmt?(node.else_keyword_loc, node.statements.body[0].location, false)
+            body
+          end
+
+        else_statements = visit_statements_node_body(statements)
+
+        bounds(node.end_keyword_loc)
+        on_kw("end")
+        bounds(node.location)
+        on_else(else_statements)
+      end
+
+      # "foo #{bar}"
+      #      ^^^^^^
+      def visit_embedded_statements_node(node)
+        bounds(node.opening_loc)
+        on_embexpr_beg(node.opening)
+
+        statements =
+          if node.statements.nil?
+            bounds(node.location)
+            on_stmts_add(on_stmts_new, on_void_stmt)
+          else
+            visit(node.statements)
+          end
+
+        bounds(node.closing_loc)
+        on_embexpr_end(node.closing)
+
+        bounds(node.location)
+        on_string_embexpr(statements)
+      end
+
+      # "foo #@bar"
+      #      ^^^^^
+      def visit_embedded_variable_node(node)
+        bounds(node.operator_loc)
+        on_embvar(node.operator)
+
+        variable = visit(node.variable)
+
+        bounds(node.location)
+        on_string_dvar(variable)
+      end
+
+      # Visit an EnsureNode node.
+      def visit_ensure_node(node)
+        bounds(node.ensure_keyword_loc)
+        on_kw("ensure")
+
+        statements =
+          if node.statements.nil?
+            [nil]
+          else
+            body = node.statements.body
+            body = [nil, *body] if void_stmt?(node.ensure_keyword_loc, body[0].location, false)
+            body
+          end
+
+        statements = visit_statements_node_body(statements)
+
+        bounds(node.location)
+        on_ensure(statements)
+      end
+
+      # false
+      # ^^^^^
+      def visit_false_node(node)
+        bounds(node.location)
+        on_var_ref(on_kw("false"))
+      end
+
+      # foo => [*, bar, *]
+      #        ^^^^^^^^^^^
+      def visit_find_pattern_node(node)
+        constant = visit(node.constant)
+
+        if node.opening_loc
+          bounds(node.opening_loc)
+          node.opening == "[" ? on_lbracket("[") : on_lparen("(")
+        end
+        bounds(node.left.operator_loc)
+        on_op("*")
+
+        left =
+          if node.left.expression.nil?
+            bounds(node.left.location)
+            on_var_field(nil)
+          else
+            visit(node.left.expression)
+          end
+
+        requireds = visit_all(node.requireds) if node.requireds.any?
+
+        bounds(node.right.operator_loc)
+        on_op("*")
+
+        right =
+          if node.right.expression.nil?
+            bounds(node.right.location)
+            on_var_field(nil)
+          else
+            visit(node.right.expression)
+          end
+
+        if node.closing_loc
+          bounds(node.closing_loc)
+          node.closing == "]" ? on_rbracket("]") : on_rparen(")")
+        end
+        bounds(node.location)
+        on_fndptn(constant, left, requireds, right)
+      end
+
+      # if foo .. bar; end
+      #    ^^^^^^^^^^
+      def visit_flip_flop_node(node)
+        left = visit(node.left)
+
+        bounds(node.operator_loc)
+        on_op(node.operator)
+
+        right = visit(node.right)
+
+        bounds(node.location)
+        if node.exclude_end?
+          on_dot3(left, right)
+        else
+          on_dot2(left, right)
+        end
+      end
+
+      # 1.0
+      # ^^^
+      def visit_float_node(node)
+        visit_number_node(node) { |text| on_float(text) }
+      end
+
+      # for foo in bar do end
+      # ^^^^^^^^^^^^^^^^^^^^^
+      def visit_for_node(node)
+        bounds(node.for_keyword_loc)
+        on_kw("for")
+
+        index = visit(node.index)
+        bounds(node.in_keyword_loc)
+        on_kw("in")
+
+        collection = visit(node.collection)
+        if node.do_keyword_loc
+          bounds(node.do_keyword_loc)
+          on_kw("do")
+        end
+        statements =
+          if node.statements.nil?
+            bounds(node.location)
+            on_stmts_add(on_stmts_new, on_void_stmt)
+          else
+            visit(node.statements)
+          end
+
+        bounds(node.end_keyword_loc)
+        on_kw("end")
+
+        bounds(node.location)
+        on_for(index, collection, statements)
+      end
+
+      # def foo(...); bar(...); end
+      #                   ^^^
+      def visit_forwarding_arguments_node(node)
+        bounds(node.location)
+        on_op("...")
+        on_args_forward
+      end
+
+      # def foo(...); end
+      #         ^^^
+      def visit_forwarding_parameter_node(node)
+        bounds(node.location)
+        on_op("...")
+        on_args_forward
+      end
+
+      # super
+      # ^^^^^
+      #
+      # super {}
+      # ^^^^^^^^
+      def visit_forwarding_super_node(node)
+        bounds(node.keyword_loc)
+        on_kw("super")
+
+        if node.block.nil?
+          bounds(node.location)
+          on_zsuper
+        else
+          block = visit(node.block)
+
+          bounds(node.location)
+          on_method_add_block(on_zsuper, block)
+        end
+      end
+
+      # $foo
+      # ^^^^
+      def visit_global_variable_read_node(node)
+        bounds(node.location)
+        on_var_ref(on_gvar(node.name.to_s))
+      end
+
+      # $foo = 1
+      # ^^^^^^^^
+      def visit_global_variable_write_node(node)
+        bounds(node.name_loc)
+        target = on_var_field(on_gvar(node.name.to_s))
+
+        bounds(node.operator_loc)
+        on_op("=")
+
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_assign(target, value)
+      end
+
+      # $foo += bar
+      # ^^^^^^^^^^^
+      def visit_global_variable_operator_write_node(node)
+        bounds(node.name_loc)
+        target = on_var_field(on_gvar(node.name.to_s))
+
+        bounds(node.binary_operator_loc)
+        operator = on_op("#{node.binary_operator}=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # $foo &&= bar
+      # ^^^^^^^^^^^^
+      def visit_global_variable_and_write_node(node)
+        bounds(node.name_loc)
+        target = on_var_field(on_gvar(node.name.to_s))
+
+        bounds(node.operator_loc)
+        operator = on_op("&&=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # $foo ||= bar
+      # ^^^^^^^^^^^^
+      def visit_global_variable_or_write_node(node)
+        bounds(node.name_loc)
+        target = on_var_field(on_gvar(node.name.to_s))
+
+        bounds(node.operator_loc)
+        operator = on_op("||=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # $foo, = bar
+      # ^^^^
+      def visit_global_variable_target_node(node)
+        bounds(node.location)
+        on_var_field(on_gvar(node.name.to_s))
+      end
+
+      # {}
+      # ^^
+      def visit_hash_node(node)
+        bounds(node.opening_loc)
+        on_lbrace("{")
+
+        elements =
+          if node.elements.any?
+            args = visit_all(node.elements)
+
+            bounds(node.elements.first.location)
+            on_assoclist_from_args(args)
+          end
+
+        bounds(node.closing_loc)
+        on_rbrace("}")
+        bounds(node.location)
+        on_hash(elements)
+      end
+
+      # foo => {}
+      #        ^^
+      def visit_hash_pattern_node(node)
+        constant = visit(node.constant)
+
+        if node.constant
+          bounds(node.opening_loc)
+          node.opening == "[" ? on_lbracket("[") : on_lparen("(")
+        elsif node.opening_loc
+          bounds(node.opening_loc)
+          on_lbrace("{")
+        end
+
+        elements =
+          if node.elements.any? || !node.rest.nil?
+            node.elements.map do |element|
+              [
+                if (key = element.key).opening_loc.nil?
+                  visit(key)
+                else
+                  bounds(key.value_loc)
+                  if (value = key.value).empty?
+                    on_string_content
+                  else
+                    on_string_add(on_string_content, on_tstring_content(value))
+                  end
+                end,
+                visit(element.value)
+              ]
+            end
+          end
+
+        rest =
+          case node.rest
+          when AssocSplatNode
+            bounds(node.rest.operator_loc)
+            on_op("**")
+            visit(node.rest.value)
+          when NoKeywordsParameterNode
+            bounds(node.rest.location)
+            on_var_field(visit(node.rest))
+          end
+
+        if node.constant
+          bounds(node.closing_loc)
+          node.closing == "]" ? on_rbracket("]") : on_rparen(")")
+        elsif node.closing_loc
+          bounds(node.closing_loc)
+          on_rbrace("}")
+        end
+        bounds(node.location)
+        on_hshptn(constant, elements, rest)
+      end
+
+      # if foo then bar end
+      # ^^^^^^^^^^^^^^^^^^^
+      #
+      # bar if foo
+      # ^^^^^^^^^^
+      #
+      # foo ? bar : baz
+      # ^^^^^^^^^^^^^^^
+      def visit_if_node(node)
+        if node.then_keyword == "?"
+          predicate = visit(node.predicate)
+
+          bounds(node.then_keyword_loc)
+          on_op("?")
+
+          truthy = visit(node.statements.body.first)
+
+          bounds(node.subsequent.else_keyword_loc)
+          on_op(":")
+
+          falsy = visit(node.subsequent.statements.body.first)
+
+          bounds(node.location)
+          on_ifop(predicate, truthy, falsy)
+        elsif node.statements.nil? || (node.predicate.location.start_offset < node.statements.location.start_offset)
+          bounds(node.if_keyword_loc)
+          on_kw(node.if_keyword)
+          predicate = visit(node.predicate)
+          if node.then_keyword_loc && node.then_keyword != "?"
+            bounds(node.then_keyword_loc)
+            on_kw("then")
+          end
+          statements =
+            if node.statements.nil?
+              bounds(node.location)
+              on_stmts_add(on_stmts_new, on_void_stmt)
+            else
+              visit(node.statements)
+            end
+          subsequent = visit(node.subsequent)
+
+          if node.end_keyword_loc && !node.subsequent
+            bounds(node.end_keyword_loc)
+            on_kw("end")
+          end
+
+          bounds(node.location)
+          if node.if_keyword == "if"
+            on_if(predicate, statements, subsequent)
+          else
+            on_elsif(predicate, statements, subsequent)
+          end
+        else
+          statements = visit(node.statements.body.first)
+          bounds(node.if_keyword_loc)
+          on_kw(node.if_keyword)
+          predicate = visit(node.predicate)
+
+          bounds(node.location)
+          on_if_mod(predicate, statements)
+        end
+      end
+
+      # 1i
+      # ^^
+      def visit_imaginary_node(node)
+        visit_number_node(node) { |text| on_imaginary(text) }
+      end
+
+      # { foo: }
+      #   ^^^^
+      def visit_implicit_node(node)
+      end
+
+      # foo { |bar,| }
+      #           ^
+      def visit_implicit_rest_node(node)
+        bounds(node.location)
+        on_excessed_comma
+      end
+
+      # case foo; in bar; end
+      # ^^^^^^^^^^^^^^^^^^^^^
+      def visit_in_node(node)
+        # This is a special case where we're not going to call on_in directly
+        # because we don't have access to the subsequent. Instead, we'll return
+        # the component parts and let the parent node handle it.
+        bounds(node.in_loc)
+        on_kw("in")
+
+        pattern = visit_pattern_node(node.pattern)
+        if node.then_loc
+          bounds(node.then_loc)
+          on_kw("then")
+        end
+        statements =
+          if node.statements.nil?
+            bounds(node.location)
+            on_stmts_add(on_stmts_new, on_void_stmt)
+          else
+            visit(node.statements)
+          end
+
+        [pattern, statements]
+      end
+
+      # foo[bar] += baz
+      # ^^^^^^^^^^^^^^^
+      def visit_index_operator_write_node(node)
+        receiver = visit(node.receiver)
+
+        bounds(node.opening_loc)
+        on_lbracket("[")
+
+        arguments, _ = visit_call_node_arguments(node.arguments, node.block, trailing_comma?(node.arguments&.location || node.location, node.closing_loc))
+
+        bounds(node.closing_loc)
+        on_rbracket("]")
+
+        bounds(node.location)
+        target = on_aref_field(receiver, arguments)
+
+        bounds(node.binary_operator_loc)
+        operator = on_op("#{node.binary_operator}=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # foo[bar] &&= baz
+      # ^^^^^^^^^^^^^^^^
+      def visit_index_and_write_node(node)
+        receiver = visit(node.receiver)
+
+        bounds(node.opening_loc)
+        on_lbracket("[")
+
+        arguments, _ = visit_call_node_arguments(node.arguments, node.block, trailing_comma?(node.arguments&.location || node.location, node.closing_loc))
+
+        bounds(node.closing_loc)
+        on_rbracket("]")
+
+        bounds(node.location)
+        target = on_aref_field(receiver, arguments)
+
+        bounds(node.operator_loc)
+        operator = on_op("&&=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # foo[bar] ||= baz
+      # ^^^^^^^^^^^^^^^^
+      def visit_index_or_write_node(node)
+        receiver = visit(node.receiver)
+
+        bounds(node.opening_loc)
+        on_lbracket("[")
+
+        arguments, _ = visit_call_node_arguments(node.arguments, node.block, trailing_comma?(node.arguments&.location || node.location, node.closing_loc))
+
+        bounds(node.closing_loc)
+        on_rbracket("]")
+
+        bounds(node.location)
+        target = on_aref_field(receiver, arguments)
+
+        bounds(node.operator_loc)
+        operator = on_op("||=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # foo[bar], = 1
+      # ^^^^^^^^
+      def visit_index_target_node(node)
+        receiver = visit(node.receiver)
+
+        bounds(node.opening_loc)
+        on_lbracket("[")
+
+        arguments, _ = visit_call_node_arguments(node.arguments, node.block, trailing_comma?(node.arguments&.location || node.location, node.closing_loc))
+
+        bounds(node.closing_loc)
+        on_rbracket("]")
+
+        bounds(node.location)
+        on_aref_field(receiver, arguments)
+      end
+
+      # @foo
+      # ^^^^
+      def visit_instance_variable_read_node(node)
+        bounds(node.location)
+        on_var_ref(on_ivar(node.name.to_s))
+      end
+
+      # @foo = 1
+      # ^^^^^^^^
+      def visit_instance_variable_write_node(node)
+        bounds(node.name_loc)
+        target = on_var_field(on_ivar(node.name.to_s))
+
+        bounds(node.operator_loc)
+        on_op("=")
+
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_assign(target, value)
+      end
+
+      # @foo += bar
+      # ^^^^^^^^^^^
+      def visit_instance_variable_operator_write_node(node)
+        bounds(node.name_loc)
+        target = on_var_field(on_ivar(node.name.to_s))
+
+        bounds(node.binary_operator_loc)
+        operator = on_op("#{node.binary_operator}=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # @foo &&= bar
+      # ^^^^^^^^^^^^
+      def visit_instance_variable_and_write_node(node)
+        bounds(node.name_loc)
+        target = on_var_field(on_ivar(node.name.to_s))
+
+        bounds(node.operator_loc)
+        operator = on_op("&&=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # @foo ||= bar
+      # ^^^^^^^^^^^^
+      def visit_instance_variable_or_write_node(node)
+        bounds(node.name_loc)
+        target = on_var_field(on_ivar(node.name.to_s))
+
+        bounds(node.operator_loc)
+        operator = on_op("||=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # @foo, = bar
+      # ^^^^
+      def visit_instance_variable_target_node(node)
+        bounds(node.location)
+        on_var_field(on_ivar(node.name.to_s))
+      end
+
+      # 1
+      # ^
+      def visit_integer_node(node)
+        visit_number_node(node) { |text| on_int(text) }
+      end
+
+      # if /foo #{bar}/ then end
+      #    ^^^^^^^^^^^^
+      def visit_interpolated_match_last_line_node(node)
+        bounds(node.opening_loc)
+        on_regexp_beg(node.opening)
+
+        bounds(node.parts.first.location)
+        parts =
+          node.parts.inject(on_regexp_new) do |content, part|
+            on_regexp_add(content, visit_string_content(part))
+          end
+
+        bounds(node.closing_loc)
+        closing = on_regexp_end(node.closing)
+
+        bounds(node.location)
+        on_regexp_literal(parts, closing)
+      end
+
+      # /foo #{bar}/
+      # ^^^^^^^^^^^^
+      def visit_interpolated_regular_expression_node(node)
+        bounds(node.opening_loc)
+        on_regexp_beg(node.opening)
+
+        bounds(node.parts.first.location)
+        parts =
+          node.parts.inject(on_regexp_new) do |content, part|
+            on_regexp_add(content, visit_string_content(part))
+          end
+
+        bounds(node.closing_loc)
+        closing = on_regexp_end(node.closing)
+
+        bounds(node.location)
+        on_regexp_literal(parts, closing)
+      end
+
+      # "foo #{bar}"
+      # ^^^^^^^^^^^^
+      def visit_interpolated_string_node(node)
+        with_string_bounds(node) do
+          if node.opening&.start_with?("<<~")
+            heredoc = visit_heredoc_string_node(node)
+
+            bounds(node.location)
+            on_string_literal(heredoc)
+          elsif !node.heredoc? && node.parts.length > 1 && node.parts.any? { |part| (part.is_a?(StringNode) || part.is_a?(InterpolatedStringNode)) && !part.opening_loc.nil? }
+            first, *rest = node.parts
+            rest.inject(visit(first)) do |content, part|
+              concat = visit(part)
+
+              bounds(part.location)
+              on_string_concat(content, concat)
+            end
+          else
+            bounds(node.parts.first.location)
+            parts =
+              node.parts.inject(on_string_content) do |content, part|
+                on_string_add(content, visit_string_content(part))
+              end
+
+            bounds(node.location)
+            on_string_literal(parts)
+          end
+        end
+      end
+
+      # :"foo #{bar}"
+      # ^^^^^^^^^^^^^
+      def visit_interpolated_symbol_node(node)
+        with_string_bounds(node) do
+          bounds(node.parts.first.location)
+          parts =
+            node.parts.inject(on_string_content) do |content, part|
+              on_string_add(content, visit_string_content(part))
+            end
+
+          bounds(node.location)
+          on_dyna_symbol(parts)
+        end
+      end
+
+      # `foo #{bar}`
+      # ^^^^^^^^^^^^
+      def visit_interpolated_x_string_node(node)
+        with_string_bounds(node) do
+          if node.opening.start_with?("<<~")
+            heredoc = visit_heredoc_x_string_node(node)
+
+            bounds(node.location)
+            on_xstring_literal(heredoc)
+          else
+            bounds(node.parts.first.location)
+            parts =
+              node.parts.inject(on_xstring_new) do |content, part|
+                on_xstring_add(content, visit_string_content(part))
+              end
+
+            bounds(node.location)
+            on_xstring_literal(parts)
+          end
+        end
+      end
+
+      # Visit an individual part of a string-like node.
+      private def visit_string_content(part)
+        if part.is_a?(StringNode)
+          bounds(part.content_loc)
+          on_tstring_content(part.content)
+        else
+          visit(part)
+        end
+      end
+
+      # -> { it }
+      #      ^^
+      def visit_it_local_variable_read_node(node)
+        bounds(node.location)
+        on_vcall(on_ident(node.slice))
+      end
+
+      # -> { it }
+      # ^^^^^^^^^
+      def visit_it_parameters_node(node)
+      end
+
+      # foo(bar: baz)
+      #     ^^^^^^^^
+      def visit_keyword_hash_node(node)
+        elements = visit_all(node.elements)
+
+        bounds(node.location)
+        on_bare_assoc_hash(elements)
+      end
+
+      # def foo(**bar); end
+      #         ^^^^^
+      #
+      # def foo(**); end
+      #         ^^
+      def visit_keyword_rest_parameter_node(node)
+        bounds(node.operator_loc)
+        on_op("**")
+
+        if node.name_loc.nil?
+          bounds(node.location)
+          on_kwrest_param(nil)
+        else
+          bounds(node.name_loc)
+          name = on_ident(node.name.to_s)
+
+          bounds(node.location)
+          on_kwrest_param(name)
+        end
+      end
+
+      # -> {}
+      def visit_lambda_node(node)
+        bounds(node.operator_loc)
+        on_tlambda(node.operator)
+
+        parameters =
+          if node.parameters.is_a?(BlockParametersNode)
+            if node.parameters.opening_loc
+              bounds(node.parameters.opening_loc)
+              on_lparen("(")
+            end
+
+            # Ripper does not track block-locals within lambdas, so we skip
+            # directly to the parameters here.
+            params =
+              if node.parameters.parameters.nil?
+                bounds(node.location)
+                on_params(nil, nil, nil, nil, nil, nil, nil)
+              else
+                visit(node.parameters.parameters)
+              end
+
+            visit_all(node.parameters.locals)
+
+            if node.parameters.closing_loc
+              bounds(node.parameters.closing_loc)
+              on_rparen(")")
+            end
+
+            if node.parameters.opening_loc.nil?
+              params
+            else
+              bounds(node.parameters.opening_loc)
+              on_paren(params)
+            end
+          else
+            bounds(node.location)
+            on_params(nil, nil, nil, nil, nil, nil, nil)
+          end
+
+        braces = node.opening == "{"
+        bounds(node.opening_loc)
+        if braces
+          on_tlambeg(node.opening)
+        else
+          on_kw("do")
+        end
+
+        body =
+          case node.body
+          when nil
+            bounds(node.location)
+            stmts = on_stmts_add(on_stmts_new, on_void_stmt)
+
+            bounds(node.location)
+            braces ? stmts : on_bodystmt(stmts, nil, nil, nil)
+          when StatementsNode
+            stmts = node.body.body
+            stmts = [nil, *stmts] if void_stmt?(node.parameters&.location || node.opening_loc, node.body.location, false)
+            stmts = visit_statements_node_body(stmts)
+
+            bounds(node.body.location)
+            braces ? stmts : on_bodystmt(stmts, nil, nil, nil)
+          when BeginNode
+            visit_body_node(node.opening_loc, node.body)
+          else
+            raise
+          end
+
+          bounds(node.closing_loc)
+        if braces
+          on_rbrace("}")
+        else
+          on_kw("end")
+        end
+
+        bounds(node.location)
+        on_lambda(parameters, body)
+      end
+
+      # foo
+      # ^^^
+      def visit_local_variable_read_node(node)
+        bounds(node.location)
+        on_var_ref(on_ident(node.slice))
+      end
+
+      # foo = 1
+      # ^^^^^^^
+      def visit_local_variable_write_node(node)
+        bounds(node.name_loc)
+        target = on_var_field(on_ident(node.name_loc.slice))
+
+        bounds(node.operator_loc)
+        on_op("=")
+
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_assign(target, value)
+      end
+
+      # foo += bar
+      # ^^^^^^^^^^
+      def visit_local_variable_operator_write_node(node)
+        bounds(node.name_loc)
+        target = on_var_field(on_ident(node.name_loc.slice))
+
+        bounds(node.binary_operator_loc)
+        operator = on_op("#{node.binary_operator}=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # foo &&= bar
+      # ^^^^^^^^^^^
+      def visit_local_variable_and_write_node(node)
+        bounds(node.name_loc)
+        target = on_var_field(on_ident(node.name_loc.slice))
+
+        bounds(node.operator_loc)
+        operator = on_op("&&=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # foo ||= bar
+      # ^^^^^^^^^^^
+      def visit_local_variable_or_write_node(node)
+        bounds(node.name_loc)
+        target = on_var_field(on_ident(node.name_loc.slice))
+
+        bounds(node.operator_loc)
+        operator = on_op("||=")
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_opassign(target, operator, value)
+      end
+
+      # foo, = bar
+      # ^^^
+      def visit_local_variable_target_node(node)
+        bounds(node.location)
+        on_var_field(on_ident(node.name.to_s))
+      end
+
+      # if /foo/ then end
+      #    ^^^^^
+      def visit_match_last_line_node(node)
+        bounds(node.opening_loc)
+        on_regexp_beg(node.opening)
+
+        bounds(node.content_loc)
+        tstring_content = on_tstring_content(node.content)
+
+        bounds(node.closing_loc)
+        closing = on_regexp_end(node.closing)
+
+        on_regexp_literal(on_regexp_add(on_regexp_new, tstring_content), closing)
+      end
+
+      # foo in bar
+      # ^^^^^^^^^^
+      def visit_match_predicate_node(node)
+        value = visit(node.value)
+        bounds(node.operator_loc)
+        on_kw("in")
+        pattern = on_in(visit_pattern_node(node.pattern), nil, nil)
+
+        on_case(value, pattern)
+      end
+
+      # foo => bar
+      # ^^^^^^^^^^
+      def visit_match_required_node(node)
+        value = visit(node.value)
+
+        bounds(node.operator_loc)
+        on_op("=>")
+
+        pattern = on_in(visit_pattern_node(node.pattern), nil, nil)
+
+        on_case(value, pattern)
+      end
+
+      # /(?<foo>foo)/ =~ bar
+      # ^^^^^^^^^^^^^^^^^^^^
+      def visit_match_write_node(node)
+        visit(node.call)
+      end
+
+      # A node that is missing from the syntax tree. This is only used in the
+      # case of a syntax error.
+      def visit_error_recovery_node(node)
+        raise "Cannot visit error recovery nodes directly."
+      end
+
+      # module Foo; end
+      # ^^^^^^^^^^^^^^^
+      def visit_module_node(node)
+        bounds(node.module_keyword_loc)
+        on_kw("module")
+
+        constant_path =
+          if node.constant_path.is_a?(ConstantReadNode)
+            bounds(node.constant_path.location)
+            on_const_ref(on_const(node.constant_path.name.to_s))
+          else
+            visit(node.constant_path)
+          end
+
+        bodystmt = visit_body_node(node.constant_path.location, node.body, true)
+
+        bounds(node.end_keyword_loc)
+        on_kw("end")
+
+        bounds(node.location)
+        on_module(constant_path, bodystmt)
+      end
+
+      # (foo, bar), bar = qux
+      # ^^^^^^^^^^
+      def visit_multi_target_node(node)
+        if node.lparen_loc
+          bounds(node.lparen_loc)
+          on_lparen("(")
+        end
+
+        bounds(node.location)
+        targets = visit_multi_target_node_targets(node.lefts, node.rest, node.rights, true)
+
+        if node.rparen_loc
+          bounds(node.rparen_loc)
+          on_rparen(")")
+        end
+
+        if node.lparen_loc.nil?
+          targets
+        else
+          bounds(node.lparen_loc)
+          on_mlhs_paren(targets)
+        end
+      end
+
+      # Visit the targets of a multi-target node.
+      private def visit_multi_target_node_targets(lefts, rest, rights, skippable)
+        if skippable && lefts.length == 1 && lefts.first.is_a?(MultiTargetNode) && rest.nil? && rights.empty?
+          return visit(lefts.first)
+        end
+
+        mlhs = on_mlhs_new
+
+        lefts.each do |left|
+          bounds(left.location)
+          mlhs = on_mlhs_add(mlhs, visit(left))
+        end
+
+        case rest
+        when nil
+          # do nothing
+        when ImplicitRestNode
+          # these do not get put into the generated tree
+          bounds(rest.location)
+          on_excessed_comma
+        else
+          bounds(rest.location)
+          mlhs = on_mlhs_add_star(mlhs, visit(rest))
+        end
+
+        if rights.any?
+          bounds(rights.first.location)
+          post = on_mlhs_new
+
+          rights.each do |right|
+            bounds(right.location)
+            post = on_mlhs_add(post, visit(right))
+          end
+
+          mlhs = on_mlhs_add_post(mlhs, post)
+        end
+
+        mlhs
+      end
+
+      # foo, bar = baz
+      # ^^^^^^^^^^^^^^
+      def visit_multi_write_node(node)
+        if node.lparen_loc
+          bounds(node.lparen_loc)
+          on_lparen("(")
+        end
+
+        bounds(node.location)
+        targets = visit_multi_target_node_targets(node.lefts, node.rest, node.rights, true)
+
+        if node.rparen_loc
+          bounds(node.rparen_loc)
+          on_rparen(")")
+        end
+
+        bounds(node.operator_loc)
+        on_op("=")
+
+        unless node.lparen_loc.nil?
+          bounds(node.lparen_loc)
+          targets = on_mlhs_paren(targets)
+        end
+
+        value = visit_write_value(node.value)
+
+        bounds(node.location)
+        on_massign(targets, value)
+      end
+
+      # next
+      # ^^^^
+      #
+      # next foo
+      # ^^^^^^^^
+      def visit_next_node(node)
+        bounds(node.keyword_loc)
+        on_kw("next")
+
+        if node.arguments.nil?
+          bounds(node.location)
+          on_next(on_args_new)
+        else
+          arguments = visit(node.arguments)
+
+          bounds(node.location)
+          on_next(arguments)
+        end
+      end
+
+      # nil
+      # ^^^
+      def visit_nil_node(node)
+        bounds(node.location)
+        on_var_ref(on_kw("nil"))
+      end
+
+      # def foo(&nil); end
+      #         ^^^^
+      def visit_no_block_parameter_node(node)
+        bounds(node.operator_loc)
+        on_op("&")
+        bounds(node.keyword_loc)
+        on_kw("nil")
+        bounds(node.location)
+        on_blockarg(:nil)
+      end
+
+      # def foo(**nil); end
+      #         ^^^^^
+      def visit_no_keywords_parameter_node(node)
+        bounds(node.operator_loc)
+        on_op("**")
+        bounds(node.keyword_loc)
+        on_kw("nil")
+        bounds(node.location)
+        on_nokw_param(nil)
+
+        :nil
+      end
+
+      # -> { _1 + _2 }
+      # ^^^^^^^^^^^^^^
+      def visit_numbered_parameters_node(node)
+      end
+
+      # $1
+      # ^^
+      def visit_numbered_reference_read_node(node)
+        bounds(node.location)
+        on_backref(node.slice)
+      end
+
+      # def foo(bar: baz); end
+      #         ^^^^^^^^
+      def visit_optional_keyword_parameter_node(node)
+        bounds(node.name_loc)
+        name = on_label("#{node.name}:")
+        value = visit(node.value)
+
+        [name, value]
+      end
+
+      # def foo(bar = 1); end
+      #         ^^^^^^^
+      def visit_optional_parameter_node(node)
+        bounds(node.name_loc)
+        name = on_ident(node.name.to_s)
+
+        bounds(node.operator_loc)
+        on_op("=")
+
+        value = visit(node.value)
+
+        [name, value]
+      end
+
+      # a or b
+      # ^^^^^^
+      def visit_or_node(node)
+        left = visit(node.left)
+
+        bounds(node.operator_loc)
+        if node.operator == "or"
+          on_kw("or")
+        else
+          on_op("||")
+        end
+
+        right = visit(node.right)
+
+        bounds(node.location)
+        on_binary(left, node.operator.to_sym, right)
+      end
+
+      # def foo(bar, *baz); end
+      #         ^^^^^^^^^
+      def visit_parameters_node(node)
+        requireds = node.requireds.map { |required| required.is_a?(MultiTargetNode) ? visit_destructured_parameter_node(required) : visit(required) } if node.requireds.any?
+        optionals = visit_all(node.optionals) if node.optionals.any?
+        rest = visit(node.rest)
+        posts = node.posts.map { |post| post.is_a?(MultiTargetNode) ? visit_destructured_parameter_node(post) : visit(post) } if node.posts.any?
+        keywords = visit_all(node.keywords) if node.keywords.any?
+        keyword_rest = visit(node.keyword_rest)
+        block = visit(node.block)
+
+        bounds(node.location)
+        on_params(requireds, optionals, rest, posts, keywords, keyword_rest, block)
+      end
+
+      # Visit a destructured positional parameter node.
+      private def visit_destructured_parameter_node(node)
+        if node.lparen_loc
+          bounds(node.lparen_loc)
+          on_lparen("(")
+        end
+
+        bounds(node.location)
+        targets = visit_multi_target_node_targets(node.lefts, node.rest, node.rights, false)
+
+        if node.rparen_loc
+          bounds(node.rparen_loc)
+          on_rparen(")")
+        end
+
+        bounds(node.lparen_loc)
+        on_mlhs_paren(targets)
+      end
+
+      # ()
+      # ^^
+      #
+      # (1)
+      # ^^^
+      def visit_parentheses_node(node)
+        bounds(node.opening_loc)
+        on_lparen("(")
+
+        body =
+          if node.body.nil?
+            on_stmts_add(on_stmts_new, on_void_stmt)
+          else
+            visit(node.body)
+          end
+
+        bounds(node.closing_loc)
+        on_rparen(")")
+        bounds(node.location)
+        on_paren(body)
+      end
+
+      # foo => ^(bar)
+      #        ^^^^^^
+      def visit_pinned_expression_node(node)
+        bounds(node.operator_loc)
+        on_op("^")
+        bounds(node.lparen_loc)
+        on_lparen("(")
+
+        expression = visit(node.expression)
+
+        bounds(node.rparen_loc)
+        on_rparen(")")
+        bounds(node.location)
+        on_begin(expression)
+      end
+
+      # foo = 1 and bar => ^foo
+      #                    ^^^^
+      def visit_pinned_variable_node(node)
+        bounds(node.operator_loc)
+        on_op("^")
+
+        visit(node.variable)
+      end
+
+      # END {}
+      # ^^^^^^
+      def visit_post_execution_node(node)
+        bounds(node.keyword_loc)
+        on_kw("END")
+        bounds(node.opening_loc)
+        on_lbrace("{")
+
+        statements =
+          if node.statements.nil?
+            bounds(node.location)
+            on_stmts_add(on_stmts_new, on_void_stmt)
+          else
+            visit(node.statements)
+          end
+
+        bounds(node.closing_loc)
+        on_rbrace("}")
+        bounds(node.location)
+        on_END(statements)
+      end
+
+      # BEGIN {}
+      # ^^^^^^^^
+      def visit_pre_execution_node(node)
+        bounds(node.keyword_loc)
+        on_kw("BEGIN")
+        bounds(node.opening_loc)
+        on_lbrace("{")
+
+        statements =
+          if node.statements.nil?
+            bounds(node.location)
+            on_stmts_add(on_stmts_new, on_void_stmt)
+          else
+            visit(node.statements)
+          end
+
+        bounds(node.closing_loc)
+        on_rbrace("}")
+        bounds(node.location)
+        on_BEGIN(statements)
+      end
+
+      # The top-level program node.
+      def visit_program_node(node)
+        body = node.statements.body
+        body = [nil] if body.empty?
+        statements = visit_statements_node_body(body)
+
+        bounds(node.location)
+        on_program(statements)
+      end
+
+      # 0..5
+      # ^^^^
+      def visit_range_node(node)
+        left = visit(node.left)
+
+        bounds(node.operator_loc)
+        on_op(node.operator)
+
+        right = visit(node.right)
+
+        bounds(node.location)
+        if node.exclude_end?
+          on_dot3(left, right)
+        else
+          on_dot2(left, right)
+        end
+      end
+
+      # 1r
+      # ^^
+      def visit_rational_node(node)
+        visit_number_node(node) { |text| on_rational(text) }
+      end
+
+      # redo
+      # ^^^^
+      def visit_redo_node(node)
+        bounds(node.location)
+        on_kw("redo")
+        on_redo
+      end
+
+      # /foo/
+      # ^^^^^
+      def visit_regular_expression_node(node)
+        bounds(node.opening_loc)
+        on_regexp_beg(node.opening)
+
+        if node.content.empty?
+          bounds(node.closing_loc)
+          closing = on_regexp_end(node.closing)
+
+          on_regexp_literal(on_regexp_new, closing)
+        else
+          bounds(node.content_loc)
+          tstring_content = on_tstring_content(node.content)
+
+          bounds(node.closing_loc)
+          closing = on_regexp_end(node.closing)
+
+          on_regexp_literal(on_regexp_add(on_regexp_new, tstring_content), closing)
+        end
+      end
+
+      # def foo(bar:); end
+      #         ^^^^
+      def visit_required_keyword_parameter_node(node)
+        bounds(node.name_loc)
+        [on_label("#{node.name}:"), false]
+      end
+
+      # def foo(bar); end
+      #         ^^^
+      def visit_required_parameter_node(node)
+        bounds(node.location)
+        on_ident(node.name.to_s)
+      end
+
+      # foo rescue bar
+      # ^^^^^^^^^^^^^^
+      def visit_rescue_modifier_node(node)
+        bounds(node.keyword_loc)
+        on_kw("rescue")
+
+        expression = visit_write_value(node.expression)
+        rescue_expression = visit(node.rescue_expression)
+
+        bounds(node.location)
+        on_rescue_mod(expression, rescue_expression)
+      end
+
+      # begin; rescue; end
+      #        ^^^^^^^
+      def visit_rescue_node(node)
+        bounds(node.keyword_loc)
+        on_kw("rescue")
+
+        exceptions =
+          case node.exceptions.length
+          when 0
+            nil
+          when 1
+            if (exception = node.exceptions.first).is_a?(SplatNode)
+              bounds(exception.location)
+              on_mrhs_add_star(on_mrhs_new, visit(exception))
+            else
+              [visit(node.exceptions.first)]
+            end
+          else
+            bounds(node.location)
+            length = node.exceptions.length
+
+            node.exceptions.each_with_index.inject(on_args_new) do |mrhs, (exception, index)|
+              arg = visit(exception)
+
+              bounds(exception.location)
+              mrhs = on_mrhs_new_from_args(mrhs) if index == length - 1
+
+              if exception.is_a?(SplatNode)
+                if index == length - 1
+                  on_mrhs_add_star(mrhs, arg)
+                else
+                  on_args_add_star(mrhs, arg)
+                end
+              else
+                if index == length - 1
+                  on_mrhs_add(mrhs, arg)
+                else
+                  on_args_add(mrhs, arg)
+                end
+              end
+            end
+          end
+
+        if node.operator_loc
+          bounds(node.operator_loc)
+          on_op("=>")
+        end
+
+        reference = visit(node.reference)
+        statements =
+          if node.statements.nil?
+            bounds(node.location)
+            on_stmts_add(on_stmts_new, on_void_stmt)
+          else
+            visit(node.statements)
+          end
+
+        subsequent = visit(node.subsequent)
+
+        bounds(node.location)
+        on_rescue(exceptions, reference, statements, subsequent)
+      end
+
+      # def foo(*bar); end
+      #         ^^^^
+      #
+      # def foo(*); end
+      #         ^
+      def visit_rest_parameter_node(node)
+        bounds(node.operator_loc)
+        on_op("*")
+
+        if node.name_loc.nil?
+          bounds(node.location)
+          on_rest_param(nil)
+        else
+          bounds(node.name_loc)
+          on_rest_param(on_ident(node.name.to_s))
+        end
+      end
+
+      # retry
+      # ^^^^^
+      def visit_retry_node(node)
+        bounds(node.location)
+        on_kw("retry")
+        on_retry
+      end
+
+      # return
+      # ^^^^^^
+      #
+      # return 1
+      # ^^^^^^^^
+      def visit_return_node(node)
+        bounds(node.keyword_loc)
+        on_kw("return")
+
+        if node.arguments.nil?
+          bounds(node.location)
+          on_return0
+        else
+          arguments = visit(node.arguments)
+
+          bounds(node.location)
+          on_return(arguments)
+        end
+      end
+
+      # self
+      # ^^^^
+      def visit_self_node(node)
+        bounds(node.location)
+        on_var_ref(on_kw("self"))
+      end
+
+      # A shareable constant.
+      def visit_shareable_constant_node(node)
+        visit(node.write)
+      end
+
+      # class << self; end
+      # ^^^^^^^^^^^^^^^^^^
+      def visit_singleton_class_node(node)
+        bounds(node.class_keyword_loc)
+        on_kw("class")
+        bounds(node.operator_loc)
+        on_op("<<")
+
+        expression = visit(node.expression)
+        bodystmt = visit_body_node(node.body&.location || node.end_keyword_loc, node.body)
+
+        bounds(node.end_keyword_loc)
+        on_kw("end")
+
+        bounds(node.location)
+        on_sclass(expression, bodystmt)
+      end
+
+      # __ENCODING__
+      # ^^^^^^^^^^^^
+      def visit_source_encoding_node(node)
+        bounds(node.location)
+        on_var_ref(on_kw("__ENCODING__"))
+      end
+
+      # __FILE__
+      # ^^^^^^^^
+      def visit_source_file_node(node)
+        bounds(node.location)
+        on_var_ref(on_kw("__FILE__"))
+      end
+
+      # __LINE__
+      # ^^^^^^^^
+      def visit_source_line_node(node)
+        bounds(node.location)
+        on_var_ref(on_kw("__LINE__"))
+      end
+
+      # foo(*bar)
+      #     ^^^^
+      #
+      # def foo((bar, *baz)); end
+      #               ^^^^
+      #
+      # def foo(*); bar(*); end
+      #                 ^
+      def visit_splat_node(node)
+        bounds(node.operator_loc)
+        on_op("*")
+        visit(node.expression)
+      end
+
+      # A list of statements.
+      def visit_statements_node(node)
+        bounds(node.location)
+        visit_statements_node_body(node.body)
+      end
+
+      # Visit the list of statements of a statements node. We support nil
+      # statements in the list. This would normally not be allowed by the
+      # structure of the prism parse tree, but we manually add them here so that
+      # we can mirror Ripper's void stmt.
+      private def visit_statements_node_body(body)
+        body.inject(on_stmts_new) do |stmts, stmt|
+          on_stmts_add(stmts, stmt.nil? ? on_void_stmt : visit(stmt))
+        end
+      end
+
+      # "foo"
+      # ^^^^^
+      def visit_string_node(node)
+        with_string_bounds(node) do
+          if (content = node.content).empty?
+            bounds(node.location)
+            on_string_literal(on_string_content)
+          elsif (opening = node.opening) == "?"
+            bounds(node.location)
+            on_CHAR("?#{node.content}")
+          elsif opening.start_with?("<<~")
+            heredoc = visit_heredoc_string_node(node.to_interpolated)
+
+            bounds(node.location)
+            on_string_literal(heredoc)
+          else
+            bounds(node.content_loc)
+            tstring_content = on_tstring_content(content)
+
+            bounds(node.location)
+            on_string_literal(on_string_add(on_string_content, tstring_content))
+          end
+        end
+      end
+
+      # Responsible for emitting the various string-like begin/end events
+      private def with_string_bounds(node)
+        # `foo "bar": baz` doesn't emit the closing location
+        assoc = !(opening = node.opening)&.include?(":") && node.closing&.end_with?(":")
+
+        is_heredoc = opening&.start_with?("<<")
+        if is_heredoc
+          bounds(node.opening_loc)
+          on_heredoc_beg(node.opening)
+        elsif opening&.start_with?(":", "%s")
+          bounds(node.opening_loc)
+          on_symbeg(node.opening)
+        elsif opening&.start_with?("`", "%x")
+          bounds(node.opening_loc)
+          on_backtick(node.opening)
+        elsif opening && !opening.start_with?("?")
+          bounds(node.opening_loc)
+          on_tstring_beg(opening)
+        end
+
+        result = yield
+        if assoc
+          if node.closing != ":"
+            bounds(node.closing_loc)
+            on_label_end(node.closing)
+          end
+          return result
+        end
+
+        if is_heredoc
+          bounds(node.closing_loc)
+          on_heredoc_end(node.closing)
+        elsif node.closing_loc
+          bounds(node.closing_loc)
+          on_tstring_end(node.closing)
+        end
+
+        result
+      end
+
+      # Ripper gives back the escaped string content but strips out the common
+      # leading whitespace. Prism gives back the unescaped string content and
+      # a location for the escaped string content. Unfortunately these don't
+      # work well together, so here we need to re-derive the common leading
+      # whitespace.
+      private def visit_heredoc_node_whitespace(parts)
+        common_whitespace = nil
+        dedent_next = true
+
+        parts.each do |part|
+          if part.is_a?(StringNode)
+            if dedent_next && !(content = part.content).chomp.empty?
+              common_whitespace = [
+                common_whitespace || Float::INFINITY,
+                content[/\A\s*/].each_char.inject(0) do |part_whitespace, char|
+                  char == "\t" ? ((part_whitespace / 8 + 1) * 8) : (part_whitespace + 1)
+                end
+              ].min
+            end
+
+            dedent_next = true
+          else
+            dedent_next = false
+          end
+        end
+
+        common_whitespace || 0
+      end
+
+      # Visit a string that is expressed using a <<~ heredoc.
+      private def visit_heredoc_node(parts, base)
+        common_whitespace = visit_heredoc_node_whitespace(parts)
+
+        if common_whitespace == 0
+          bounds(parts.first.location)
+
+          string = []
+          result = base
+
+          parts.each do |part|
+            if part.is_a?(StringNode)
+              if string.empty?
+                string = [part]
+              else
+                string << part
+              end
+            else
+              unless string.empty?
+                bounds(string[0].location)
+                result = yield result, on_tstring_content(string.map(&:content).join)
+                string = []
+              end
+
+              result = yield result, visit(part)
+            end
+          end
+
+          unless string.empty?
+            bounds(string[0].location)
+            result = yield result, on_tstring_content(string.map(&:content).join)
+          end
+
+          result
+        else
+          bounds(parts.first.location)
+          result =
+            parts.inject(base) do |string_content, part|
+              yield string_content, visit_string_content(part)
+            end
+
+          bounds(parts.first.location)
+          on_heredoc_dedent(result, common_whitespace)
+        end
+      end
+
+      # Visit a heredoc node that is representing a string.
+      private def visit_heredoc_string_node(node)
+        bounds(node.location)
+        visit_heredoc_node(node.parts, on_string_content) do |parts, part|
+          on_string_add(parts, part)
+        end
+      end
+
+      # Visit a heredoc node that is representing an xstring.
+      private def visit_heredoc_x_string_node(node)
+        bounds(node.location)
+        visit_heredoc_node(node.parts, on_xstring_new) do |parts, part|
+          on_xstring_add(parts, part)
+        end
+      end
+
+      # super(foo)
+      # ^^^^^^^^^^
+      def visit_super_node(node)
+        bounds(node.keyword_loc)
+        on_kw("super")
+
+        if node.lparen_loc
+          bounds(node.lparen_loc)
+          on_lparen("(")
+        end
+
+        arguments, block_node = visit_call_node_arguments(node.arguments, node.block, trailing_comma?(node.arguments&.location || node.location, node.rparen_loc || node.location))
+
+        if node.rparen_loc
+          bounds(node.rparen_loc)
+          on_rparen(")")
+        end
+
+        block = visit(block_node)
+
+        if !node.lparen_loc.nil?
+          bounds(node.lparen_loc)
+          arguments = on_arg_paren(arguments)
+        end
+
+        bounds(node.location)
+        call = on_super(arguments)
+
+        if block_node
+          bounds(node.block.location)
+          on_method_add_block(call, block)
+        else
+          call
+        end
+      end
+
+      # :foo
+      # ^^^^
+      def visit_symbol_node(node)
+        with_string_bounds(node) do
+          if node.value_loc.nil?
+            bounds(node.location)
+            on_dyna_symbol(on_string_content)
+          elsif (opening = node.opening)&.match?(/^%s|['"]:?$/)
+            bounds(node.value_loc)
+            content = on_string_add(on_string_content, on_tstring_content(node.value))
+            bounds(node.location)
+            on_dyna_symbol(content)
+          elsif (closing = node.closing) == ":"
+            bounds(node.location)
+            on_label("#{node.value}:")
+          elsif opening.nil? && node.closing_loc.nil?
+            bounds(node.value_loc)
+            on_symbol_literal(visit_token(node.value))
+          else
+            bounds(node.value_loc)
+            on_symbol_literal(on_symbol(visit_token(node.value)))
+          end
+        end
+      end
+
+      # true
+      # ^^^^
+      def visit_true_node(node)
+        bounds(node.location)
+        on_var_ref(on_kw("true"))
+      end
+
+      # undef foo
+      # ^^^^^^^^^
+      def visit_undef_node(node)
+        bounds(node.keyword_loc)
+        on_kw("undef")
+
+        names = visit_all(node.names)
+
+        bounds(node.location)
+        on_undef(names)
+      end
+
+      # unless foo; bar end
+      # ^^^^^^^^^^^^^^^^^^^
+      #
+      # bar unless foo
+      # ^^^^^^^^^^^^^^
+      def visit_unless_node(node)
+        if node.statements.nil? || (node.predicate.location.start_offset < node.statements.location.start_offset)
+          bounds(node.keyword_loc)
+          on_kw("unless")
+          predicate = visit(node.predicate)
+          if node.then_keyword_loc
+            bounds(node.then_keyword_loc)
+            on_kw("then")
+          end
+          statements =
+            if node.statements.nil?
+              bounds(node.location)
+              on_stmts_add(on_stmts_new, on_void_stmt)
+            else
+              visit(node.statements)
+            end
+          else_clause = visit(node.else_clause)
+
+          if node.end_keyword_loc && !node.else_clause
+            bounds(node.end_keyword_loc)
+            on_kw("end")
+          end
+
+          bounds(node.location)
+          on_unless(predicate, statements, else_clause)
+        else
+          statements = visit(node.statements.body.first)
+          bounds(node.keyword_loc)
+          on_kw("unless")
+          predicate = visit(node.predicate)
+
+          bounds(node.location)
+          on_unless_mod(predicate, statements)
+        end
+      end
+
+      # until foo; bar end
+      # ^^^^^^^^^^^^^^^^^
+      #
+      # bar until foo
+      # ^^^^^^^^^^^^^
+      def visit_until_node(node)
+        bounds(node.keyword_loc)
+        on_kw("until")
+
+        if node.statements.nil? || (node.predicate.location.start_offset < node.statements.location.start_offset)
+          if node.do_keyword_loc
+            bounds(node.do_keyword_loc)
+            on_kw("do")
+          end
+          predicate = visit(node.predicate)
+          statements =
+            if node.statements.nil?
+              bounds(node.location)
+              on_stmts_add(on_stmts_new, on_void_stmt)
+            else
+              visit(node.statements)
+            end
+
+          if node.closing_loc
+            bounds(node.closing_loc)
+            on_kw("end")
+          end
+
+          bounds(node.location)
+          on_until(predicate, statements)
+        else
+          statements = visit(node.statements.body.first)
+          predicate = visit(node.predicate)
+
+          bounds(node.location)
+          on_until_mod(predicate, statements)
+        end
+      end
+
+      # case foo; when bar; end
+      #           ^^^^^^^^^^^^^
+      def visit_when_node(node)
+        # This is a special case where we're not going to call on_when directly
+        # because we don't have access to the subsequent. Instead, we'll return
+        # the component parts and let the parent node handle it.
+        bounds(node.keyword_loc)
+        on_kw("when")
+
+        conditions = visit_arguments(node.conditions)
+        if node.then_keyword_loc
+          bounds(node.then_keyword_loc)
+          on_kw("then")
+        end
+        statements =
+          if node.statements.nil?
+            bounds(node.location)
+            on_stmts_add(on_stmts_new, on_void_stmt)
+          else
+            visit(node.statements)
+          end
+
+        [conditions, statements]
+      end
+
+      # while foo; bar end
+      # ^^^^^^^^^^^^^^^^^^
+      #
+      # bar while foo
+      # ^^^^^^^^^^^^^
+      def visit_while_node(node)
+        if node.statements.nil? || (node.predicate.location.start_offset < node.statements.location.start_offset)
+          bounds(node.keyword_loc)
+          on_kw("while")
+          if node.do_keyword_loc
+            bounds(node.do_keyword_loc)
+            on_kw("do")
+          end
+          predicate = visit(node.predicate)
+          if node.closing_loc
+            bounds(node.closing_loc)
+            on_kw("end")
+          end
+          statements =
+            if node.statements.nil?
+              bounds(node.location)
+              on_stmts_add(on_stmts_new, on_void_stmt)
+            else
+              visit(node.statements)
+            end
+
+          bounds(node.location)
+          on_while(predicate, statements)
+        else
+          statements = visit(node.statements.body.first)
+          bounds(node.keyword_loc)
+          on_kw("while")
+          predicate = visit(node.predicate)
+
+          bounds(node.location)
+          on_while_mod(predicate, statements)
+        end
+      end
+
+      # `foo`
+      # ^^^^^
+      def visit_x_string_node(node)
+        with_string_bounds(node) do
+          if node.unescaped.empty?
+            bounds(node.location)
+            on_xstring_literal(on_xstring_new)
+          elsif node.opening.start_with?("<<~")
+            heredoc = visit_heredoc_x_string_node(node.to_interpolated)
+
+            bounds(node.location)
+            on_xstring_literal(heredoc)
+          else
+            bounds(node.content_loc)
+            content = on_tstring_content(node.content)
+
+            bounds(node.location)
+            on_xstring_literal(on_xstring_add(on_xstring_new, content))
+          end
+        end
+      end
+
+      # yield
+      # ^^^^^
+      #
+      # yield 1
+      # ^^^^^^^
+      def visit_yield_node(node)
+        bounds(node.keyword_loc)
+        on_kw("yield")
+
+        if node.arguments.nil? && node.lparen_loc.nil?
+          bounds(node.location)
+          on_yield0
+        else
+          if node.lparen_loc
+            bounds(node.lparen_loc)
+            on_lparen("(")
+          end
+
+          arguments =
+            if node.arguments.nil?
+              bounds(node.location)
+              on_args_new
+            else
+              visit(node.arguments)
+            end
+
+          unless node.lparen_loc.nil?
+            bounds(node.rparen_loc)
+            on_rparen(")")
+            bounds(node.lparen_loc)
+            arguments = on_paren(arguments)
+          end
+
+          bounds(node.location)
+          on_yield(arguments)
+        end
+      end
+
+      private
+
+      # Lazily initialize the parse result.
+      def result
+        @result ||= Prism.parse(source, partial_script: true, version: "current", freeze: true, encoding: source.encoding)
+      end
+
+      def line_and_column_cache
+        @line_and_column_cache ||= LineAndColumnCache.new(result.source)
+      end
+
+      ##########################################################################
+      # Helpers
+      ##########################################################################
+
+      # Returns true if there is a comma between the two locations.
+      def trailing_comma?(left, right)
+        source.byteslice(left.end_offset...right.start_offset).include?(",")
+      end
+
+      # Returns true if there is a semicolon between the two locations.
+      def void_stmt?(left, right, allow_newline)
+        pattern = allow_newline ? /[;\n]/ : /;/
+        source.byteslice(left.end_offset...right.start_offset).match?(pattern)
+      end
+
+      # Visit the string content of a particular node. This method is used to
+      # split into the various token types.
+      def visit_token(token, allow_keywords = true)
+        if token == "."
+          on_period(token)
+        elsif token == "`"
+          on_backtick(token)
+        elsif allow_keywords && KEYWORDS.include?(token)
+          on_kw(token)
+        elsif token.start_with?("_")
+          on_ident(token)
+        elsif token.match?(/^[[:upper:]]\w*$/)
+          on_const(token)
+        elsif token.start_with?("@@")
+          on_cvar(token)
+        elsif token.start_with?("@")
+          on_ivar(token)
+        elsif token.start_with?("$")
+          on_gvar(token)
+        elsif token.match?(/^[[:punct:]]/)
+          on_op(token)
+        else
+          on_ident(token)
+        end
+      end
+
+      # Visit either `.`, `&.`, or `::`.
+      def visit_call_operator(token)
+        token == "." ? on_period(token) : on_op(token)
+      end
+
+      # Visit a node that represents a number. We need to explicitly handle the
+      # unary - operator.
+      def visit_number_node(node)
+        slice = node.slice
+        location = node.location
+
+        if slice[0] == "-"
+          bounds(location.copy(length: 1))
+          on_op("-")
+
+          bounds(location.copy(start_offset: location.start_offset + 1))
+          value = yield slice[1..-1]
+
+          bounds(node.location)
+          on_unary(:-@, value)
+        else
+          bounds(location)
+          yield slice
+        end
+      end
+
+      # Visit a node that represents a write value. This is used to handle the
+      # special case of an implicit array that is generated without brackets.
+      def visit_write_value(node)
+        if node.is_a?(ArrayNode) && node.opening_loc.nil?
+          elements = node.elements
+          length = elements.length
+
+          bounds(elements.first.location)
+          elements.each_with_index.inject((elements.first.is_a?(SplatNode) && length == 1) ? on_mrhs_new : on_args_new) do |args, (element, index)|
+            arg = visit(element)
+            bounds(element.location)
+
+            if index == length - 1
+              if element.is_a?(SplatNode)
+                mrhs = index == 0 ? args : on_mrhs_new_from_args(args)
+                on_mrhs_add_star(mrhs, arg)
+              else
+                on_mrhs_add(on_mrhs_new_from_args(args), arg)
+              end
+            else
+              case element
+              when BlockArgumentNode
+                on_args_add_block(args, arg)
+              when SplatNode
+                on_args_add_star(args, arg)
+              else
+                on_args_add(args, arg)
+              end
+            end
+          end
+        else
+          visit(node)
+        end
+      end
+
+      # This method is responsible for updating lineno and column information
+      # to reflect the current node.
+      def bounds(location)
+        @lineno, @column = line_and_column_cache.line_and_column(location.start_offset)
+      end
+
+      # :startdoc:
+
+      ##########################################################################
+      # Ripper interface
+      ##########################################################################
+
+      # :stopdoc:
+      def _dispatch_0; end
+      def _dispatch_1(arg); arg end
+      def _dispatch_2(arg, _); arg end
+      def _dispatch_3(arg, _, _); arg end
+      def _dispatch_4(arg, _, _, _); arg end
+      def _dispatch_5(arg, _, _, _, _); arg end
+      def _dispatch_7(arg, _, _, _, _, _, _); arg end
+      # :startdoc:
+
+      #
+      # Parser Events
+      #
+
+      PARSER_EVENT_TABLE.each do |id, arity|
+        alias_method "on_#{id}", "_dispatch_#{arity}"
+      end
+
+      # This method is called when weak warning is produced by the parser.
+      # +fmt+ and +args+ is printf style.
+      def warn(fmt, *args)
+      end
+
+      # This method is called when strong warning is produced by the parser.
+      # +fmt+ and +args+ is printf style.
+      def warning(fmt, *args)
+      end
+
+      # This method is called when the parser found syntax error.
+      def compile_error(msg)
+      end
+
+      #
+      # Scanner Events
+      #
+
+      SCANNER_EVENTS.each do |id|
+        alias_method "on_#{id}", :_dispatch_1
+      end
+
+      # This method is provided by the Ripper C extension. It is called when a
+      # string needs to be dedented because of a tilde heredoc. It is expected
+      # that it will modify the string in place and return the number of bytes
+      # that were removed.
+      def dedent_string(string, width)
+        whitespace = 0
+        cursor = 0
+
+        while cursor < string.length && string[cursor].match?(/\s/) && whitespace < width
+          if string[cursor] == "\t"
+            whitespace = ((whitespace / 8 + 1) * 8)
+            break if whitespace > width
+          else
+            whitespace += 1
+          end
+
+          cursor += 1
+        end
+
+        string.replace(string[cursor..])
+        cursor
+      end
+    end
+  end
+end
diff --git a/lib/prism/translation/ripper/filter.rb b/lib/prism/translation/ripper/filter.rb
new file mode 100644
index 0000000000..19deef2d37
--- /dev/null
+++ b/lib/prism/translation/ripper/filter.rb
@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+module Prism
+  module Translation
+    class Ripper
+      class Filter # :nodoc:
+        # :stopdoc:
+        def initialize(src, filename = '-', lineno = 1)
+          @__lexer = Lexer.new(src, filename, lineno)
+          @__line = nil
+          @__col = nil
+          @__state = nil
+        end
+
+        def filename
+          @__lexer.filename
+        end
+
+        def lineno
+          @__line
+        end
+
+        def column
+          @__col
+        end
+
+        def state
+          @__state
+        end
+
+        def parse(init = nil)
+          data = init
+          @__lexer.lex.each do |pos, event, tok, state|
+            @__line, @__col = *pos
+            @__state = state
+            data = if respond_to?(event, true)
+                  then __send__(event, tok, data)
+                  else on_default(event, tok, data)
+                  end
+          end
+          data
+        end
+
+        private
+
+        def on_default(event, token, data)
+          data
+        end
+        # :startdoc:
+      end
+    end
+  end
+end
diff --git a/lib/prism/translation/ripper/lexer.rb b/lib/prism/translation/ripper/lexer.rb
new file mode 100644
index 0000000000..c6aeae4bd7
--- /dev/null
+++ b/lib/prism/translation/ripper/lexer.rb
@@ -0,0 +1,133 @@
+# frozen_string_literal: true
+# :markup: markdown
+
+require_relative "../ripper"
+
+module Prism
+  module Translation
+    class Ripper
+      class Lexer < Ripper # :nodoc:
+        class State # :nodoc:
+          attr_reader :to_int, :to_s
+
+          def initialize(i)
+            @to_int = i
+            @to_s = Ripper.lex_state_name(i)
+            freeze
+          end
+
+          def [](index)
+            case index
+            when 0, :to_int
+              @to_int
+            when 1, :to_s
+              @to_s
+            else
+              nil
+            end
+          end
+
+          alias to_i to_int
+          alias inspect to_s
+          def pretty_print(q) q.text(to_s) end
+          def ==(i) super or to_int == i end
+          def &(i) self.class.new(to_int & i) end
+          def |(i) self.class.new(to_int | i) end
+          def allbits?(i) to_int.allbits?(i) end
+          def anybits?(i) to_int.anybits?(i) end
+          def nobits?(i) to_int.nobits?(i) end
+
+          # Instances are frozen and there are only a handful of them so we
+          # cache them here.
+          STATES = Hash.new { |hash, key| hash[key] = State.new(key) }
+          private_constant :STATES
+
+          def self.[](i)
+            STATES[i]
+          end
+        end
+
+        class Elem # :nodoc:
+          attr_accessor :pos, :event, :tok, :state, :message
+
+          def initialize(pos, event, tok, state, message = nil)
+            @pos = pos
+            @event = event
+            @tok = tok
+            @state = State[state]
+            @message = message
+          end
+
+          def [](index)
+            case index
+            when 0, :pos
+              @pos
+            when 1, :event
+              @event
+            when 2, :tok
+              @tok
+            when 3, :state
+              @state
+            when 4, :message
+              @message
+            else
+              nil
+            end
+          end
+
+          def inspect
+            "#<#{self.class}: #{event}@#{pos[0]}:#{pos[1]}:#{state}: #{tok.inspect}#{": " if message}#{message}>"
+          end
+
+          alias to_s inspect
+
+          def pretty_print(q)
+            q.group(2, "#<#{self.class}:", ">") {
+              q.breakable
+              q.text("#{event}@#{pos[0]}:#{pos[1]}")
+              q.breakable
+              state.pretty_print(q)
+              q.breakable
+              q.text("token: ")
+              tok.pretty_print(q)
+              if message
+                q.breakable
+                q.text("message: ")
+                q.text(message)
+              end
+            }
+          end
+
+          def to_a
+            if @message
+              [@pos, @event, @tok, @state, @message]
+            else
+              [@pos, @event, @tok, @state]
+            end
+          end
+        end
+
+        # Pretty much just the same as Prism.lex_compat.
+        def lex(raise_errors: false)
+          Ripper.lex(@source, filename, lineno, raise_errors: raise_errors)
+        end
+
+        # Returns the lex_compat result wrapped in `Elem`. Errors are omitted.
+        # Since ripper is a streaming parser, tokens are expected to be emitted in the order
+        # that the parser encounters them. This is not implemented.
+        def parse(...)
+          lex(...).map do |position, event, token, state|
+            Elem.new(position, event, token, state.to_int)
+          end
+        end
+
+        # Similar to parse but ripper sorts the elements by position in the source. Also
+        # includes errors. Since prism does error recovery, in cases of syntax errors
+        # the result may differ greatly compared to ripper.
+        def scan(...)
+          parse(...)
+        end
+      end
+    end
+  end
+end
diff --git a/lib/prism/translation/ripper/sexp.rb b/lib/prism/translation/ripper/sexp.rb
new file mode 100644
index 0000000000..46c0333544
--- /dev/null
+++ b/lib/prism/translation/ripper/sexp.rb
@@ -0,0 +1,118 @@
+# frozen_string_literal: true
+# :markup: markdown
+
+require_relative "../ripper"
+
+module Prism
+  module Translation
+    class Ripper
+      # This class mirrors the ::Ripper::SexpBuilder subclass of ::Ripper that
+      # returns the arrays of [type, *children].
+      class SexpBuilder < Ripper # :nodoc:
+        attr_reader :error
+
+        private
+
+        def dedent_element(e, width)
+          if (n = dedent_string(e[1], width)) > 0
+            e[2][1] += n
+          end
+          e
+        end
+
+        def on_heredoc_dedent(val, width)
+          sub = proc do |cont|
+            cont.map! do |e|
+              if Array === e
+                case e[0]
+                when :@tstring_content
+                  e = dedent_element(e, width)
+                when /_add\z/
+                  e[1] = sub[e[1]]
+                end
+              elsif String === e
+                dedent_string(e, width)
+              end
+              e
+            end
+          end
+          sub[val]
+          val
+        end
+
+        events = private_instance_methods(false).grep(/\Aon_/) {$'.to_sym}
+        (PARSER_EVENTS - events).each do |event|
+          module_eval(<<-End, __FILE__, __LINE__ + 1)
+            def on_#{event}(*args)
+              args.unshift :#{event}
+            end
+          End
+        end
+
+        SCANNER_EVENTS.each do |event|
+          module_eval(<<-End, __FILE__, __LINE__ + 1)
+            def on_#{event}(tok)
+              [:@#{event}, tok, [lineno(), column()]]
+            end
+          End
+        end
+
+        def on_error(mesg)
+          @error = mesg
+        end
+        remove_method :on_parse_error
+        alias on_parse_error on_error
+        alias compile_error on_error
+      end
+
+      # This class mirrors the ::Ripper::SexpBuilderPP subclass of ::Ripper that
+      # returns the same values as ::Ripper::SexpBuilder except with a couple of
+      # niceties that flatten linked lists into arrays.
+      class SexpBuilderPP < SexpBuilder # :nodoc:
+        private
+
+        def on_heredoc_dedent(val, width)
+          val.map! do |e|
+            next e if Symbol === e and /_content\z/ =~ e
+            if Array === e and e[0] == :@tstring_content
+              e = dedent_element(e, width)
+            elsif String === e
+              dedent_string(e, width)
+            end
+            e
+          end
+          val
+        end
+
+        def _dispatch_event_new
+          []
+        end
+
+        def _dispatch_event_push(list, item)
+          list.push item
+          list
+        end
+
+        def on_mlhs_paren(list)
+          [:mlhs, *list]
+        end
+
+        def on_mlhs_add_star(list, star)
+          list.push([:rest_param, star])
+        end
+
+        def on_mlhs_add_post(list, post)
+          list.concat(post)
+        end
+
+        PARSER_EVENT_TABLE.each do |event, arity|
+          if /_new\z/ =~ event and arity == 0
+            alias_method "on_#{event}", :_dispatch_event_new
+          elsif /_add\z/ =~ event
+            alias_method "on_#{event}", :_dispatch_event_push
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/prism/translation/ripper/shim.rb b/lib/prism/translation/ripper/shim.rb
new file mode 100644
index 0000000000..00ed625da3
--- /dev/null
+++ b/lib/prism/translation/ripper/shim.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+# This writes the prism ripper translation into the Ripper constant so that
+# users can transparently use Ripper without any changes.
+# :stopdoc:
+Ripper = Prism::Translation::Ripper
+# :startdoc:
diff --git a/lib/prism/translation/ruby_parser.rb b/lib/prism/translation/ruby_parser.rb
new file mode 100644
index 0000000000..42bc5ee658
--- /dev/null
+++ b/lib/prism/translation/ruby_parser.rb
@@ -0,0 +1,1676 @@
+# frozen_string_literal: true
+# :markup: markdown
+
+begin
+  require "sexp"
+rescue LoadError
+  warn(%q{Error: Unable to load sexp. Add `gem "sexp_processor"` to your Gemfile.})
+  exit(1)
+end
+
+class RubyParser # :nodoc:
+  class SyntaxError < RuntimeError # :nodoc:
+  end
+end
+
+module Prism
+  module Translation
+    # This module is the entry-point for converting a prism syntax tree into the
+    # seattlerb/ruby_parser gem's syntax tree.
+    class RubyParser
+      # A prism visitor that builds Sexp objects.
+      class Compiler < ::Prism::Compiler # :nodoc:
+        # This is the name of the file that we are compiling. We set it on every
+        # Sexp object that is generated, and also use it to compile `__FILE__`
+        # nodes.
+        attr_reader :file
+
+        # Class variables will change their type based on if they are inside of
+        # a method definition or not, so we need to track that state.
+        attr_reader :in_def
+
+        # Some nodes will change their representation if they are inside of a
+        # pattern, so we need to track that state.
+        attr_reader :in_pattern
+
+        # Initialize a new compiler with the given file name.
+        def initialize(file, in_def: false, in_pattern: false)
+          @file = file
+          @in_def = in_def
+          @in_pattern = in_pattern
+        end
+
+        # alias foo bar
+        # ^^^^^^^^^^^^^
+        def visit_alias_method_node(node)
+          s(node, :alias, visit(node.new_name), visit(node.old_name))
+        end
+
+        # alias $foo $bar
+        # ^^^^^^^^^^^^^^^
+        def visit_alias_global_variable_node(node)
+          s(node, :valias, node.new_name.name, node.old_name.name)
+        end
+
+        # foo => bar | baz
+        #        ^^^^^^^^^
+        def visit_alternation_pattern_node(node)
+          s(node, :or, visit(node.left), visit(node.right))
+        end
+
+        # a and b
+        # ^^^^^^^
+        def visit_and_node(node)
+          left = visit(node.left)
+
+          if left[0] == :and
+            # ruby_parser has the and keyword as right-associative as opposed to
+            # prism which has it as left-associative. We reverse that
+            # associativity here.
+            nest = left
+            nest = nest[2] while nest[2][0] == :and
+            nest[2] = s(node, :and, nest[2], visit(node.right))
+            left
+          else
+            s(node, :and, left, visit(node.right))
+          end
+        end
+
+        # []
+        # ^^
+        def visit_array_node(node)
+          if in_pattern
+            s(node, :array_pat, nil).concat(visit_all(node.elements))
+          else
+            s(node, :array).concat(visit_all(node.elements))
+          end
+        end
+
+        # foo => [bar]
+        #        ^^^^^
+        def visit_array_pattern_node(node)
+          if node.constant.nil? && node.requireds.empty? && node.rest.nil? && node.posts.empty?
+            s(node, :array_pat)
+          else
+            result = s(node, :array_pat, visit_pattern_constant(node.constant)).concat(visit_all(node.requireds))
+
+            case node.rest
+            when SplatNode
+              result << :"*#{node.rest.expression&.name}"
+            when ImplicitRestNode
+              result << :*
+
+              # This doesn't make any sense at all, but since we're trying to
+              # replicate the behavior directly, we'll copy it.
+              result.line(666)
+            end
+
+            result.concat(visit_all(node.posts))
+          end
+        end
+
+        # foo(bar)
+        #     ^^^
+        def visit_arguments_node(node)
+          raise "Cannot visit arguments directly"
+        end
+
+        # { a: 1 }
+        #   ^^^^
+        def visit_assoc_node(node)
+          [visit(node.key), visit(node.value)]
+        end
+
+        # def foo(**); bar(**); end
+        #                  ^^
+        #
+        # { **foo }
+        #   ^^^^^
+        def visit_assoc_splat_node(node)
+          if node.value.nil?
+            [s(node, :kwsplat)]
+          else
+            [s(node, :kwsplat, visit(node.value))]
+          end
+        end
+
+        # $+
+        # ^^
+        def visit_back_reference_read_node(node)
+          s(node, :back_ref, node.name.to_s.delete_prefix("$").to_sym)
+        end
+
+        # begin end
+        # ^^^^^^^^^
+        def visit_begin_node(node)
+          result = node.statements.nil? ? s(node, :nil) : visit(node.statements)
+
+          if !node.rescue_clause.nil?
+            if !node.statements.nil?
+              result = s(node.statements, :rescue, result, visit(node.rescue_clause))
+            else
+              result = s(node.rescue_clause, :rescue, visit(node.rescue_clause))
+            end
+
+            current = node.rescue_clause
+            until (current = current.subsequent).nil?
+              result << visit(current)
+            end
+          end
+
+          if !node.else_clause&.statements.nil?
+            result << visit(node.else_clause)
+          end
+
+          if !node.ensure_clause.nil?
+            if !node.statements.nil? || !node.rescue_clause.nil? || !node.else_clause.nil?
+              result = s(node.statements || node.rescue_clause || node.else_clause || node.ensure_clause, :ensure, result, visit(node.ensure_clause))
+            else
+              result = s(node.ensure_clause, :ensure, visit(node.ensure_clause))
+            end
+          end
+
+          result
+        end
+
+        # foo(&bar)
+        #     ^^^^
+        def visit_block_argument_node(node)
+          s(node, :block_pass).tap do |result|
+            result << visit(node.expression) unless node.expression.nil?
+          end
+        end
+
+        # foo { |; bar| }
+        #          ^^^
+        def visit_block_local_variable_node(node)
+          node.name
+        end
+
+        # A block on a keyword or method call.
+        def visit_block_node(node)
+          s(node, :block_pass, visit(node.expression))
+        end
+
+        # def foo(&bar); end
+        #         ^^^^
+        def visit_block_parameter_node(node)
+          :"&#{node.name}"
+        end
+
+        # A block's parameters.
+        def visit_block_parameters_node(node)
+          # If this block parameters has no parameters and is using pipes, then
+          # it inherits its location from its shadow locals, even if they're not
+          # on the same lines as the pipes.
+          shadow_loc = true
+
+          result =
+            if node.parameters.nil?
+              s(node, :args)
+            else
+              shadow_loc = false
+              visit(node.parameters)
+            end
+
+          if node.opening == "("
+            result.line = node.opening_loc.start_line
+            result.line_max = node.closing_loc.end_line
+            shadow_loc = false
+          end
+
+          if node.locals.any?
+            shadow = s(node, :shadow).concat(visit_all(node.locals))
+            shadow.line = node.locals.first.location.start_line
+            shadow.line_max = node.locals.last.location.end_line
+            result << shadow
+
+            if shadow_loc
+              result.line = shadow.line
+              result.line_max = shadow.line_max
+            end
+          end
+
+          result
+        end
+
+        # break
+        # ^^^^^
+        #
+        # break foo
+        # ^^^^^^^^^
+        def visit_break_node(node)
+          if node.arguments.nil?
+            s(node, :break)
+          elsif node.arguments.arguments.length == 1
+            s(node, :break, visit(node.arguments.arguments.first))
+          else
+            s(node, :break, s(node.arguments, :array).concat(visit_all(node.arguments.arguments)))
+          end
+        end
+
+        # foo
+        # ^^^
+        #
+        # foo.bar
+        # ^^^^^^^
+        #
+        # foo.bar() {}
+        # ^^^^^^^^^^^^
+        def visit_call_node(node)
+          case node.name
+          when :!~
+            return s(node, :not, visit(node.copy(name: :"=~")))
+          when :=~
+            if node.arguments&.arguments&.length == 1 && node.block.nil?
+              case node.receiver
+              when StringNode
+                return s(node, :match3, visit(node.arguments.arguments.first), visit(node.receiver))
+              when RegularExpressionNode, InterpolatedRegularExpressionNode
+                return s(node, :match2, visit(node.receiver), visit(node.arguments.arguments.first))
+              end
+
+              case node.arguments.arguments.first
+              when RegularExpressionNode, InterpolatedRegularExpressionNode
+                return s(node, :match3, visit(node.arguments.arguments.first), visit(node.receiver))
+              end
+            end
+          end
+
+          type = node.attribute_write? ? :attrasgn : :call
+          type = :"safe_#{type}" if node.safe_navigation?
+
+          arguments = node.arguments&.arguments || []
+          write_value = arguments.pop if type == :attrasgn
+          block = node.block
+
+          if block.is_a?(BlockArgumentNode)
+            arguments << block
+            block = nil
+          end
+
+          result = s(node, type, visit(node.receiver), node.name).concat(visit_all(arguments))
+          result << visit_write_value(write_value) unless write_value.nil?
+
+          visit_block(node, result, block)
+        end
+
+        # foo.bar += baz
+        # ^^^^^^^^^^^^^^^
+        def visit_call_operator_write_node(node)
+          if op_asgn?(node)
+            s(node, op_asgn_type(node, :op_asgn), visit(node.receiver), visit_write_value(node.value), node.read_name, node.binary_operator)
+          else
+            s(node, op_asgn_type(node, :op_asgn2), visit(node.receiver), node.write_name, node.binary_operator, visit_write_value(node.value))
+          end
+        end
+
+        # foo.bar &&= baz
+        # ^^^^^^^^^^^^^^^
+        def visit_call_and_write_node(node)
+          if op_asgn?(node)
+            s(node, op_asgn_type(node, :op_asgn), visit(node.receiver), visit_write_value(node.value), node.read_name, :"&&")
+          else
+            s(node, op_asgn_type(node, :op_asgn2), visit(node.receiver), node.write_name, :"&&", visit_write_value(node.value))
+          end
+        end
+
+        # foo.bar ||= baz
+        # ^^^^^^^^^^^^^^^
+        def visit_call_or_write_node(node)
+          if op_asgn?(node)
+            s(node, op_asgn_type(node, :op_asgn), visit(node.receiver), visit_write_value(node.value), node.read_name, :"||")
+          else
+            s(node, op_asgn_type(node, :op_asgn2), visit(node.receiver), node.write_name, :"||", visit_write_value(node.value))
+          end
+        end
+
+        # Call nodes with operators following them will either be op_asgn or
+        # op_asgn2 nodes. That is determined by their call operator and their
+        # right-hand side.
+        private def op_asgn?(node)
+          node.call_operator == "::" || (node.value.is_a?(CallNode) && node.value.opening_loc.nil? && !node.value.arguments.nil?)
+        end
+
+        # Call nodes with operators following them can use &. as an operator,
+        # which changes their type by prefixing "safe_".
+        private def op_asgn_type(node, type)
+          node.safe_navigation? ? :"safe_#{type}" : type
+        end
+
+        # foo.bar, = 1
+        # ^^^^^^^
+        def visit_call_target_node(node)
+          s(node, :attrasgn, visit(node.receiver), node.name)
+        end
+
+        # foo => bar => baz
+        #        ^^^^^^^^^^
+        def visit_capture_pattern_node(node)
+          visit(node.target) << visit(node.value)
+        end
+
+        # case foo; when bar; end
+        # ^^^^^^^^^^^^^^^^^^^^^^^
+        def visit_case_node(node)
+          s(node, :case, visit(node.predicate)).concat(visit_all(node.conditions)) << visit(node.else_clause)
+        end
+
+        # case foo; in bar; end
+        # ^^^^^^^^^^^^^^^^^^^^^
+        def visit_case_match_node(node)
+          s(node, :case, visit(node.predicate)).concat(visit_all(node.conditions)) << visit(node.else_clause)
+        end
+
+        # class Foo; end
+        # ^^^^^^^^^^^^^^
+        def visit_class_node(node)
+          name =
+            if node.constant_path.is_a?(ConstantReadNode)
+              node.name
+            else
+              visit(node.constant_path)
+            end
+
+          result =
+            if node.body.nil?
+              s(node, :class, name, visit(node.superclass))
+            elsif node.body.is_a?(StatementsNode)
+              compiler = copy_compiler(in_def: false)
+              s(node, :class, name, visit(node.superclass)).concat(node.body.body.map { |child| child.accept(compiler) })
+            else
+              s(node, :class, name, visit(node.superclass), node.body.accept(copy_compiler(in_def: false)))
+            end
+
+          attach_comments(result, node)
+          result
+        end
+
+        # @@foo
+        # ^^^^^
+        def visit_class_variable_read_node(node)
+          s(node, :cvar, node.name)
+        end
+
+        # @@foo = 1
+        # ^^^^^^^^^
+        def visit_class_variable_write_node(node)
+          s(node, class_variable_write_type, node.name, visit_write_value(node.value))
+        end
+
+        # @@foo += bar
+        # ^^^^^^^^^^^^
+        def visit_class_variable_operator_write_node(node)
+          s(node, class_variable_write_type, node.name, s(node, :call, s(node, :cvar, node.name), node.binary_operator, visit_write_value(node.value)))
+        end
+
+        # @@foo &&= bar
+        # ^^^^^^^^^^^^^
+        def visit_class_variable_and_write_node(node)
+          s(node, :op_asgn_and, s(node, :cvar, node.name), s(node, class_variable_write_type, node.name, visit_write_value(node.value)))
+        end
+
+        # @@foo ||= bar
+        # ^^^^^^^^^^^^^
+        def visit_class_variable_or_write_node(node)
+          s(node, :op_asgn_or, s(node, :cvar, node.name), s(node, class_variable_write_type, node.name, visit_write_value(node.value)))
+        end
+
+        # @@foo, = bar
+        # ^^^^^
+        def visit_class_variable_target_node(node)
+          s(node, class_variable_write_type, node.name)
+        end
+
+        # If a class variable is written within a method definition, it has a
+        # different type than everywhere else.
+        private def class_variable_write_type
+          in_def ? :cvasgn : :cvdecl
+        end
+
+        # Foo
+        # ^^^
+        def visit_constant_read_node(node)
+          s(node, :const, node.name)
+        end
+
+        # Foo = 1
+        # ^^^^^^^
+        #
+        # Foo, Bar = 1
+        # ^^^  ^^^
+        def visit_constant_write_node(node)
+          s(node, :cdecl, node.name, visit_write_value(node.value))
+        end
+
+        # Foo += bar
+        # ^^^^^^^^^^^
+        def visit_constant_operator_write_node(node)
+          s(node, :cdecl, node.name, s(node, :call, s(node, :const, node.name), node.binary_operator, visit_write_value(node.value)))
+        end
+
+        # Foo &&= bar
+        # ^^^^^^^^^^^^
+        def visit_constant_and_write_node(node)
+          s(node, :op_asgn_and, s(node, :const, node.name), s(node, :cdecl, node.name, visit(node.value)))
+        end
+
+        # Foo ||= bar
+        # ^^^^^^^^^^^^
+        def visit_constant_or_write_node(node)
+          s(node, :op_asgn_or, s(node, :const, node.name), s(node, :cdecl, node.name, visit(node.value)))
+        end
+
+        # Foo, = bar
+        # ^^^
+        def visit_constant_target_node(node)
+          s(node, :cdecl, node.name)
+        end
+
+        # Foo::Bar
+        # ^^^^^^^^
+        def visit_constant_path_node(node)
+          if node.parent.nil?
+            s(node, :colon3, node.name)
+          else
+            s(node, :colon2, visit(node.parent), node.name)
+          end
+        end
+
+        # Foo::Bar = 1
+        # ^^^^^^^^^^^^
+        #
+        # Foo::Foo, Bar::Bar = 1
+        # ^^^^^^^^  ^^^^^^^^
+        def visit_constant_path_write_node(node)
+          s(node, :cdecl, visit(node.target), visit_write_value(node.value))
+        end
+
+        # Foo::Bar += baz
+        # ^^^^^^^^^^^^^^^
+        def visit_constant_path_operator_write_node(node)
+          s(node, :op_asgn, visit(node.target), node.binary_operator, visit_write_value(node.value))
+        end
+
+        # Foo::Bar &&= baz
+        # ^^^^^^^^^^^^^^^^
+        def visit_constant_path_and_write_node(node)
+          s(node, :op_asgn_and, visit(node.target), visit_write_value(node.value))
+        end
+
+        # Foo::Bar ||= baz
+        # ^^^^^^^^^^^^^^^^
+        def visit_constant_path_or_write_node(node)
+          s(node, :op_asgn_or, visit(node.target), visit_write_value(node.value))
+        end
+
+        # Foo::Bar, = baz
+        # ^^^^^^^^
+        def visit_constant_path_target_node(node)
+          inner =
+            if node.parent.nil?
+              s(node, :colon3, node.name)
+            else
+              s(node, :colon2, visit(node.parent), node.name)
+            end
+
+          s(node, :const, inner)
+        end
+
+        # def foo; end
+        # ^^^^^^^^^^^^
+        #
+        # def self.foo; end
+        # ^^^^^^^^^^^^^^^^^
+        def visit_def_node(node)
+          name = node.name_loc.slice.to_sym
+          result =
+            if node.receiver.nil?
+              s(node, :defn, name)
+            else
+              s(node, :defs, visit(node.receiver), name)
+            end
+
+          attach_comments(result, node)
+          result.line(node.name_loc.start_line)
+
+          if node.parameters.nil?
+            result << s(node, :args).line(node.name_loc.start_line)
+          else
+            result << visit(node.parameters)
+          end
+
+          if node.body.nil?
+            result << s(node, :nil)
+          elsif node.body.is_a?(StatementsNode)
+            compiler = copy_compiler(in_def: true)
+            result.concat(node.body.body.map { |child| child.accept(compiler) })
+          else
+            result << node.body.accept(copy_compiler(in_def: true))
+          end
+        end
+
+        # defined? a
+        # ^^^^^^^^^^
+        #
+        # defined?(a)
+        # ^^^^^^^^^^^
+        def visit_defined_node(node)
+          s(node, :defined, visit(node.value))
+        end
+
+        # if foo then bar else baz end
+        #                 ^^^^^^^^^^^^
+        def visit_else_node(node)
+          visit(node.statements)
+        end
+
+        # "foo #{bar}"
+        #      ^^^^^^
+        def visit_embedded_statements_node(node)
+          result = s(node, :evstr)
+          result << visit(node.statements) unless node.statements.nil?
+          result
+        end
+
+        # "foo #@bar"
+        #      ^^^^^
+        def visit_embedded_variable_node(node)
+          s(node, :evstr, visit(node.variable))
+        end
+
+        # begin; foo; ensure; bar; end
+        #             ^^^^^^^^^^^^
+        def visit_ensure_node(node)
+          node.statements.nil? ? s(node, :nil) : visit(node.statements)
+        end
+
+        # false
+        # ^^^^^
+        def visit_false_node(node)
+          s(node, :false)
+        end
+
+        # foo => [*, bar, *]
+        #        ^^^^^^^^^^^
+        def visit_find_pattern_node(node)
+          s(node, :find_pat, visit_pattern_constant(node.constant), :"*#{node.left.expression&.name}", *visit_all(node.requireds), :"*#{node.right.expression&.name}")
+        end
+
+        # if foo .. bar; end
+        #    ^^^^^^^^^^
+        def visit_flip_flop_node(node)
+          if node.left.is_a?(IntegerNode) && node.right.is_a?(IntegerNode)
+            s(node, :lit, Range.new(node.left.value, node.right.value, node.exclude_end?))
+          else
+            s(node, node.exclude_end? ? :flip3 : :flip2, visit(node.left), visit(node.right))
+          end
+        end
+
+        # 1.0
+        # ^^^
+        def visit_float_node(node)
+          s(node, :lit, node.value)
+        end
+
+        # for foo in bar do end
+        # ^^^^^^^^^^^^^^^^^^^^^
+        def visit_for_node(node)
+          s(node, :for, visit(node.collection), visit(node.index), visit(node.statements))
+        end
+
+        # def foo(...); bar(...); end
+        #                   ^^^
+        def visit_forwarding_arguments_node(node)
+          s(node, :forward_args)
+        end
+
+        # def foo(...); end
+        #         ^^^
+        def visit_forwarding_parameter_node(node)
+          s(node, :forward_args)
+        end
+
+        # super
+        # ^^^^^
+        #
+        # super {}
+        # ^^^^^^^^
+        def visit_forwarding_super_node(node)
+          visit_block(node, s(node, :zsuper), node.block)
+        end
+
+        # $foo
+        # ^^^^
+        def visit_global_variable_read_node(node)
+          s(node, :gvar, node.name)
+        end
+
+        # $foo = 1
+        # ^^^^^^^^
+        def visit_global_variable_write_node(node)
+          s(node, :gasgn, node.name, visit_write_value(node.value))
+        end
+
+        # $foo += bar
+        # ^^^^^^^^^^^
+        def visit_global_variable_operator_write_node(node)
+          s(node, :gasgn, node.name, s(node, :call, s(node, :gvar, node.name), node.binary_operator, visit(node.value)))
+        end
+
+        # $foo &&= bar
+        # ^^^^^^^^^^^^
+        def visit_global_variable_and_write_node(node)
+          s(node, :op_asgn_and, s(node, :gvar, node.name), s(node, :gasgn, node.name, visit_write_value(node.value)))
+        end
+
+        # $foo ||= bar
+        # ^^^^^^^^^^^^
+        def visit_global_variable_or_write_node(node)
+          s(node, :op_asgn_or, s(node, :gvar, node.name), s(node, :gasgn, node.name, visit_write_value(node.value)))
+        end
+
+        # $foo, = bar
+        # ^^^^
+        def visit_global_variable_target_node(node)
+          s(node, :gasgn, node.name)
+        end
+
+        # {}
+        # ^^
+        def visit_hash_node(node)
+          s(node, :hash).concat(node.elements.flat_map { |element| visit(element) })
+        end
+
+        # foo => {}
+        #        ^^
+        def visit_hash_pattern_node(node)
+          result = s(node, :hash_pat, visit_pattern_constant(node.constant)).concat(node.elements.flat_map { |element| visit(element) })
+
+          case node.rest
+          when AssocSplatNode
+            result << s(node.rest, :kwrest, :"**#{node.rest.value&.name}")
+          when NoKeywordsParameterNode
+            result << visit(node.rest)
+          end
+
+          result
+        end
+
+        # if foo then bar end
+        # ^^^^^^^^^^^^^^^^^^^
+        #
+        # bar if foo
+        # ^^^^^^^^^^
+        #
+        # foo ? bar : baz
+        # ^^^^^^^^^^^^^^^
+        def visit_if_node(node)
+          s(node, :if, visit(node.predicate), visit(node.statements), visit(node.subsequent))
+        end
+
+        # 1i
+        def visit_imaginary_node(node)
+          s(node, :lit, node.value)
+        end
+
+        # { foo: }
+        #   ^^^^
+        def visit_implicit_node(node)
+        end
+
+        # foo { |bar,| }
+        #           ^
+        def visit_implicit_rest_node(node)
+        end
+
+        # case foo; in bar; end
+        # ^^^^^^^^^^^^^^^^^^^^^
+        def visit_in_node(node)
+          pattern =
+            if node.pattern.is_a?(ConstantPathNode)
+              s(node.pattern, :const, visit(node.pattern))
+            else
+              node.pattern.accept(copy_compiler(in_pattern: true))
+            end
+
+          s(node, :in, pattern).concat(node.statements.nil? ? [nil] : visit_all(node.statements.body))
+        end
+
+        # foo[bar] += baz
+        # ^^^^^^^^^^^^^^^
+        def visit_index_operator_write_node(node)
+          arglist = nil
+
+          if !node.arguments.nil? || !node.block.nil?
+            arglist = s(node, :arglist).concat(visit_all(node.arguments&.arguments || []))
+            arglist << visit(node.block) if !node.block.nil?
+          end
+
+          s(node, :op_asgn1, visit(node.receiver), arglist, node.binary_operator, visit_write_value(node.value))
+        end
+
+        # foo[bar] &&= baz
+        # ^^^^^^^^^^^^^^^^
+        def visit_index_and_write_node(node)
+          arglist = nil
+
+          if !node.arguments.nil? || !node.block.nil?
+            arglist = s(node, :arglist).concat(visit_all(node.arguments&.arguments || []))
+            arglist << visit(node.block) if !node.block.nil?
+          end
+
+          s(node, :op_asgn1, visit(node.receiver), arglist, :"&&", visit_write_value(node.value))
+        end
+
+        # foo[bar] ||= baz
+        # ^^^^^^^^^^^^^^^^
+        def visit_index_or_write_node(node)
+          arglist = nil
+
+          if !node.arguments.nil? || !node.block.nil?
+            arglist = s(node, :arglist).concat(visit_all(node.arguments&.arguments || []))
+            arglist << visit(node.block) if !node.block.nil?
+          end
+
+          s(node, :op_asgn1, visit(node.receiver), arglist, :"||", visit_write_value(node.value))
+        end
+
+        # foo[bar], = 1
+        # ^^^^^^^^
+        def visit_index_target_node(node)
+          arguments = visit_all(node.arguments&.arguments || [])
+          arguments << visit(node.block) unless node.block.nil?
+
+          s(node, :attrasgn, visit(node.receiver), :[]=).concat(arguments)
+        end
+
+        # @foo
+        # ^^^^
+        def visit_instance_variable_read_node(node)
+          s(node, :ivar, node.name)
+        end
+
+        # @foo = 1
+        # ^^^^^^^^
+        def visit_instance_variable_write_node(node)
+          s(node, :iasgn, node.name, visit_write_value(node.value))
+        end
+
+        # @foo += bar
+        # ^^^^^^^^^^^
+        def visit_instance_variable_operator_write_node(node)
+          s(node, :iasgn, node.name, s(node, :call, s(node, :ivar, node.name), node.binary_operator, visit_write_value(node.value)))
+        end
+
+        # @foo &&= bar
+        # ^^^^^^^^^^^^
+        def visit_instance_variable_and_write_node(node)
+          s(node, :op_asgn_and, s(node, :ivar, node.name), s(node, :iasgn, node.name, visit(node.value)))
+        end
+
+        # @foo ||= bar
+        # ^^^^^^^^^^^^
+        def visit_instance_variable_or_write_node(node)
+          s(node, :op_asgn_or, s(node, :ivar, node.name), s(node, :iasgn, node.name, visit(node.value)))
+        end
+
+        # @foo, = bar
+        # ^^^^
+        def visit_instance_variable_target_node(node)
+          s(node, :iasgn, node.name)
+        end
+
+        # 1
+        # ^
+        def visit_integer_node(node)
+          s(node, :lit, node.value)
+        end
+
+        # if /foo #{bar}/ then end
+        #    ^^^^^^^^^^^^
+        def visit_interpolated_match_last_line_node(node)
+          parts = visit_interpolated_parts(node.parts)
+          regexp =
+            if parts.length == 1
+              s(node, :lit, Regexp.new(parts.first, node.options))
+            else
+              s(node, :dregx).concat(parts).tap do |result|
+                options = node.options
+                result << options if options != 0
+              end
+            end
+
+          s(node, :match, regexp)
+        end
+
+        # /foo #{bar}/
+        # ^^^^^^^^^^^^
+        def visit_interpolated_regular_expression_node(node)
+          parts = visit_interpolated_parts(node.parts)
+
+          if parts.length == 1
+            s(node, :lit, Regexp.new(parts.first, node.options))
+          else
+            s(node, :dregx).concat(parts).tap do |result|
+              options = node.options
+              result << options if options != 0
+            end
+          end
+        end
+
+        # "foo #{bar}"
+        # ^^^^^^^^^^^^
+        def visit_interpolated_string_node(node)
+          parts = visit_interpolated_parts(node.parts)
+          parts.length == 1 ? s(node, :str, parts.first) : s(node, :dstr).concat(parts)
+        end
+
+        # :"foo #{bar}"
+        # ^^^^^^^^^^^^^
+        def visit_interpolated_symbol_node(node)
+          parts = visit_interpolated_parts(node.parts)
+          parts.length == 1 ? s(node, :lit, parts.first.to_sym) : s(node, :dsym).concat(parts)
+        end
+
+        # `foo #{bar}`
+        # ^^^^^^^^^^^^
+        def visit_interpolated_x_string_node(node)
+          source = node.heredoc? ? node.parts.first : node
+          parts = visit_interpolated_parts(node.parts)
+          parts.length == 1 ? s(source, :xstr, parts.first) : s(source, :dxstr).concat(parts)
+        end
+
+        # Visit the interpolated content of the string-like node.
+        private def visit_interpolated_parts(parts)
+          visited = []
+
+          parts.each do |part|
+            result = visit(part)
+
+            if result[0] == :evstr && result[1]
+              if result[1][0] == :str
+                visited << result[1]
+              elsif result[1][0] == :dstr
+                visited.concat(result[1][1..-1])
+              else
+                visited << result
+              end
+              visited << :space
+            elsif result[0] == :dstr
+              if !visited.empty? && part.parts[0].is_a?(StringNode)
+                # If we are in the middle of an implicitly concatenated string,
+                # we should not have a bare string as the first part. In this
+                # case we need to visit just that first part and then we can
+                # push the rest of the parts onto the visited array.
+                result[1] = visit(part.parts[0])
+              end
+              visited.concat(result[1..-1])
+            else
+              visited << result
+            end
+          end
+
+          state = :beginning #: :beginning | :string_content | :interpolated_content
+          results = []
+
+          visited.each_with_index do |result, index|
+            case state
+            when :beginning
+              if result.is_a?(String)
+                results << result
+                state = :string_content
+              elsif result.is_a?(Array) && result[0] == :str
+                results << result[1]
+                state = :string_content
+              else
+                results << ""
+                results << result
+                state = :interpolated_content
+              end
+            when :string_content
+              if result == :space
+                # continue
+              elsif result.is_a?(String)
+                results[0] = "#{results[0]}#{result}"
+              elsif result.is_a?(Array) && result[0] == :str
+                results[0] = "#{results[0]}#{result[1]}"
+              else
+                results << result
+                state = :interpolated_content
+              end
+            when :interpolated_content
+              if result == :space
+                # continue
+              elsif visited[index - 1] != :space && result.is_a?(Array) && result[0] == :str && results[-1][0] == :str && (results[-1].line_max == result.line)
+                results[-1][1] = "#{results[-1][1]}#{result[1]}"
+                results[-1].line_max = result.line_max
+              else
+                results << result
+              end
+            end
+          end
+
+          results
+        end
+
+        # -> { it }
+        #      ^^
+        def visit_it_local_variable_read_node(node)
+          s(node, :call, nil, :it)
+        end
+
+        # foo(bar: baz)
+        #     ^^^^^^^^
+        def visit_keyword_hash_node(node)
+          s(node, :hash).concat(node.elements.flat_map { |element| visit(element) })
+        end
+
+        # def foo(**bar); end
+        #         ^^^^^
+        #
+        # def foo(**); end
+        #         ^^
+        def visit_keyword_rest_parameter_node(node)
+          :"**#{node.name}"
+        end
+
+        # -> {}
+        def visit_lambda_node(node)
+          parameters =
+            case node.parameters
+            when nil, ItParametersNode, NumberedParametersNode
+              0
+            else
+              visit(node.parameters)
+            end
+
+          if node.body.nil?
+            s(node, :iter, s(node, :lambda), parameters)
+          else
+            s(node, :iter, s(node, :lambda), parameters, visit(node.body))
+          end
+        end
+
+        # foo
+        # ^^^
+        def visit_local_variable_read_node(node)
+          if node.name.match?(/^_\d$/)
+            s(node, :call, nil, node.name)
+          else
+            s(node, :lvar, node.name)
+          end
+        end
+
+        # foo = 1
+        # ^^^^^^^
+        def visit_local_variable_write_node(node)
+          s(node, :lasgn, node.name, visit_write_value(node.value))
+        end
+
+        # foo += bar
+        # ^^^^^^^^^^
+        def visit_local_variable_operator_write_node(node)
+          s(node, :lasgn, node.name, s(node, :call, s(node, :lvar, node.name), node.binary_operator, visit_write_value(node.value)))
+        end
+
+        # foo &&= bar
+        # ^^^^^^^^^^^
+        def visit_local_variable_and_write_node(node)
+          s(node, :op_asgn_and, s(node, :lvar, node.name), s(node, :lasgn, node.name, visit_write_value(node.value)))
+        end
+
+        # foo ||= bar
+        # ^^^^^^^^^^^
+        def visit_local_variable_or_write_node(node)
+          s(node, :op_asgn_or, s(node, :lvar, node.name), s(node, :lasgn, node.name, visit_write_value(node.value)))
+        end
+
+        # foo, = bar
+        # ^^^
+        def visit_local_variable_target_node(node)
+          s(node, :lasgn, node.name)
+        end
+
+        # if /foo/ then end
+        #    ^^^^^
+        def visit_match_last_line_node(node)
+          s(node, :match, s(node, :lit, Regexp.new(node.unescaped, node.options)))
+        end
+
+        # foo in bar
+        # ^^^^^^^^^^
+        def visit_match_predicate_node(node)
+          s(node, :case, visit(node.value), s(node, :in, node.pattern.accept(copy_compiler(in_pattern: true)), nil), nil)
+        end
+
+        # foo => bar
+        # ^^^^^^^^^^
+        def visit_match_required_node(node)
+          s(node, :case, visit(node.value), s(node, :in, node.pattern.accept(copy_compiler(in_pattern: true)), nil), nil)
+        end
+
+        # /(?<foo>foo)/ =~ bar
+        # ^^^^^^^^^^^^^^^^^^^^
+        def visit_match_write_node(node)
+          s(node, :match2, visit(node.call.receiver), visit(node.call.arguments.arguments.first))
+        end
+
+        # A node that is missing from the syntax tree. This is only used in the
+        # case of a syntax error. The parser gem doesn't have such a concept, so
+        # we invent our own here.
+        def visit_error_recovery_node(node)
+          raise "Cannot visit error recovery node directly"
+        end
+
+        # module Foo; end
+        # ^^^^^^^^^^^^^^^
+        def visit_module_node(node)
+          name =
+            if node.constant_path.is_a?(ConstantReadNode)
+              node.name
+            else
+              visit(node.constant_path)
+            end
+
+          result =
+            if node.body.nil?
+              s(node, :module, name)
+            elsif node.body.is_a?(StatementsNode)
+              compiler = copy_compiler(in_def: false)
+              s(node, :module, name).concat(node.body.body.map { |child| child.accept(compiler) })
+            else
+              s(node, :module, name, node.body.accept(copy_compiler(in_def: false)))
+            end
+
+          attach_comments(result, node)
+          result
+        end
+
+        # foo, bar = baz
+        # ^^^^^^^^
+        def visit_multi_target_node(node)
+          targets = [*node.lefts]
+          targets << node.rest if !node.rest.nil? && !node.rest.is_a?(ImplicitRestNode)
+          targets.concat(node.rights)
+
+          s(node, :masgn, s(node, :array).concat(visit_all(targets)))
+        end
+
+        # foo, bar = baz
+        # ^^^^^^^^^^^^^^
+        def visit_multi_write_node(node)
+          targets = [*node.lefts]
+          targets << node.rest if !node.rest.nil? && !node.rest.is_a?(ImplicitRestNode)
+          targets.concat(node.rights)
+
+          value =
+            if node.value.is_a?(ArrayNode) && node.value.opening_loc.nil?
+              if node.value.elements.length == 1 && node.value.elements.first.is_a?(SplatNode)
+                visit(node.value.elements.first)
+              else
+                visit(node.value)
+              end
+            else
+              s(node.value, :to_ary, visit(node.value))
+            end
+
+          s(node, :masgn, s(node, :array).concat(visit_all(targets)), value)
+        end
+
+        # next
+        # ^^^^
+        #
+        # next foo
+        # ^^^^^^^^
+        def visit_next_node(node)
+          if node.arguments.nil?
+            s(node, :next)
+          elsif node.arguments.arguments.length == 1
+            argument = node.arguments.arguments.first
+            s(node, :next, argument.is_a?(SplatNode) ? s(node, :svalue, visit(argument)) : visit(argument))
+          else
+            s(node, :next, s(node, :array).concat(visit_all(node.arguments.arguments)))
+          end
+        end
+
+        # nil
+        # ^^^
+        def visit_nil_node(node)
+          s(node, :nil)
+        end
+
+        # def foo(&nil); end
+        #         ^^^^
+        def visit_no_block_parameter_node(node)
+          :"&nil"
+        end
+
+        # def foo(**nil); end
+        #         ^^^^^
+        def visit_no_keywords_parameter_node(node)
+          in_pattern ? s(node, :kwrest, :"**nil") : :"**nil"
+        end
+
+        # -> { _1 + _2 }
+        # ^^^^^^^^^^^^^^
+        def visit_numbered_parameters_node(node)
+          raise "Cannot visit numbered parameters directly"
+        end
+
+        # $1
+        # ^^
+        def visit_numbered_reference_read_node(node)
+          s(node, :nth_ref, node.number)
+        end
+
+        # def foo(bar: baz); end
+        #         ^^^^^^^^
+        def visit_optional_keyword_parameter_node(node)
+          s(node, :kwarg, node.name, visit(node.value))
+        end
+
+        # def foo(bar = 1); end
+        #         ^^^^^^^
+        def visit_optional_parameter_node(node)
+          s(node, :lasgn, node.name, visit(node.value))
+        end
+
+        # a or b
+        # ^^^^^^
+        def visit_or_node(node)
+          left = visit(node.left)
+
+          if left[0] == :or
+            # ruby_parser has the or keyword as right-associative as opposed to
+            # prism which has it as left-associative. We reverse that
+            # associativity here.
+            nest = left
+            nest = nest[2] while nest[2][0] == :or
+            nest[2] = s(node, :or, nest[2], visit(node.right))
+            left
+          else
+            s(node, :or, left, visit(node.right))
+          end
+        end
+
+        # def foo(bar, *baz); end
+        #         ^^^^^^^^^
+        def visit_parameters_node(node)
+          children =
+            node.each_child_node.map do |element|
+              if element.is_a?(MultiTargetNode)
+                visit_destructured_parameter(element)
+              else
+                visit(element)
+              end
+            end
+
+          s(node, :args).concat(children)
+        end
+
+        # def foo((bar, baz)); end
+        #         ^^^^^^^^^^
+        private def visit_destructured_parameter(node)
+          children =
+            [*node.lefts, *node.rest, *node.rights].map do |child|
+              case child
+              when RequiredParameterNode
+                visit(child)
+              when MultiTargetNode
+                visit_destructured_parameter(child)
+              when SplatNode
+                :"*#{child.expression&.name}"
+              else
+                raise
+              end
+            end
+
+          s(node, :masgn).concat(children)
+        end
+
+        # ()
+        # ^^
+        #
+        # (1)
+        # ^^^
+        def visit_parentheses_node(node)
+          if node.body.nil?
+            s(node, :nil)
+          else
+            visit(node.body)
+          end
+        end
+
+        # foo => ^(bar)
+        #        ^^^^^^
+        def visit_pinned_expression_node(node)
+          node.expression.accept(copy_compiler(in_pattern: false))
+        end
+
+        # foo = 1 and bar => ^foo
+        #                    ^^^^
+        def visit_pinned_variable_node(node)
+          if node.variable.is_a?(LocalVariableReadNode) && node.variable.name.match?(/^_\d$/)
+            s(node, :lvar, node.variable.name)
+          else
+            visit(node.variable)
+          end
+        end
+
+        # END {}
+        def visit_post_execution_node(node)
+          s(node, :iter, s(node, :postexe), 0, visit(node.statements))
+        end
+
+        # BEGIN {}
+        def visit_pre_execution_node(node)
+          s(node, :iter, s(node, :preexe), 0, visit(node.statements))
+        end
+
+        # The top-level program node.
+        def visit_program_node(node)
+          visit(node.statements)
+        end
+
+        # 0..5
+        # ^^^^
+        def visit_range_node(node)
+          if !in_pattern && !node.left.nil? && !node.right.nil? && ([node.left.type, node.right.type] - %i[nil_node integer_node]).empty?
+            left = node.left.value if node.left.is_a?(IntegerNode)
+            right = node.right.value if node.right.is_a?(IntegerNode)
+            s(node, :lit, Range.new(left, right, node.exclude_end?))
+          else
+            s(node, node.exclude_end? ? :dot3 : :dot2, visit_range_bounds_node(node.left), visit_range_bounds_node(node.right))
+          end
+        end
+
+        # If the bounds of a range node are empty parentheses, then they do not
+        # get replaced by their usual s(:nil), but instead are s(:begin).
+        private def visit_range_bounds_node(node)
+          if node.is_a?(ParenthesesNode) && node.body.nil?
+            s(node, :begin)
+          else
+            visit(node)
+          end
+        end
+
+        # 1r
+        # ^^
+        def visit_rational_node(node)
+          s(node, :lit, node.value)
+        end
+
+        # redo
+        # ^^^^
+        def visit_redo_node(node)
+          s(node, :redo)
+        end
+
+        # /foo/
+        # ^^^^^
+        def visit_regular_expression_node(node)
+          s(node, :lit, Regexp.new(node.unescaped, node.options))
+        end
+
+        # def foo(bar:); end
+        #         ^^^^
+        def visit_required_keyword_parameter_node(node)
+          s(node, :kwarg, node.name)
+        end
+
+        # def foo(bar); end
+        #         ^^^
+        def visit_required_parameter_node(node)
+          node.name
+        end
+
+        # foo rescue bar
+        # ^^^^^^^^^^^^^^
+        def visit_rescue_modifier_node(node)
+          s(node, :rescue, visit(node.expression), s(node.rescue_expression, :resbody, s(node.rescue_expression, :array), visit(node.rescue_expression)))
+        end
+
+        # begin; rescue; end
+        #        ^^^^^^^
+        def visit_rescue_node(node)
+          exceptions =
+            if node.exceptions.length == 1 && node.exceptions.first.is_a?(SplatNode)
+              visit(node.exceptions.first)
+            else
+              s(node, :array).concat(visit_all(node.exceptions))
+            end
+
+          if !node.reference.nil?
+            exceptions << (visit(node.reference) << s(node.reference, :gvar, :"$!"))
+          end
+
+          s(node, :resbody, exceptions).concat(node.statements.nil? ? [nil] : visit_all(node.statements.body))
+        end
+
+        # def foo(*bar); end
+        #         ^^^^
+        #
+        # def foo(*); end
+        #         ^
+        def visit_rest_parameter_node(node)
+          :"*#{node.name}"
+        end
+
+        # retry
+        # ^^^^^
+        def visit_retry_node(node)
+          s(node, :retry)
+        end
+
+        # return
+        # ^^^^^^
+        #
+        # return 1
+        # ^^^^^^^^
+        def visit_return_node(node)
+          if node.arguments.nil?
+            s(node, :return)
+          elsif node.arguments.arguments.length == 1
+            argument = node.arguments.arguments.first
+            s(node, :return, argument.is_a?(SplatNode) ? s(node, :svalue, visit(argument)) : visit(argument))
+          else
+            s(node, :return, s(node, :array).concat(visit_all(node.arguments.arguments)))
+          end
+        end
+
+        # self
+        # ^^^^
+        def visit_self_node(node)
+          s(node, :self)
+        end
+
+        # A shareable constant.
+        def visit_shareable_constant_node(node)
+          visit(node.write)
+        end
+
+        # class << self; end
+        # ^^^^^^^^^^^^^^^^^^
+        def visit_singleton_class_node(node)
+          s(node, :sclass, visit(node.expression)).tap do |sexp|
+            sexp << node.body.accept(copy_compiler(in_def: false)) unless node.body.nil?
+          end
+        end
+
+        # __ENCODING__
+        # ^^^^^^^^^^^^
+        def visit_source_encoding_node(node)
+          # TODO
+          s(node, :colon2, s(node, :const, :Encoding), :UTF_8)
+        end
+
+        # __FILE__
+        # ^^^^^^^^
+        def visit_source_file_node(node)
+          s(node, :str, node.filepath)
+        end
+
+        # __LINE__
+        # ^^^^^^^^
+        def visit_source_line_node(node)
+          s(node, :lit, node.location.start_line)
+        end
+
+        # foo(*bar)
+        #     ^^^^
+        #
+        # def foo((bar, *baz)); end
+        #               ^^^^
+        #
+        # def foo(*); bar(*); end
+        #                 ^
+        def visit_splat_node(node)
+          if node.expression.nil?
+            s(node, :splat)
+          else
+            s(node, :splat, visit(node.expression))
+          end
+        end
+
+        # A list of statements.
+        def visit_statements_node(node)
+          first, *rest = node.body
+
+          if rest.empty?
+            visit(first)
+          else
+            s(node, :block).concat(visit_all(node.body))
+          end
+        end
+
+        # "foo"
+        # ^^^^^
+        def visit_string_node(node)
+          unescaped = node.unescaped
+
+          if node.forced_binary_encoding?
+            unescaped = unescaped.dup
+            unescaped.force_encoding(Encoding::BINARY)
+          end
+
+          s(node, :str, unescaped)
+        end
+
+        # super(foo)
+        # ^^^^^^^^^^
+        def visit_super_node(node)
+          arguments = node.arguments&.arguments || []
+          block = node.block
+
+          if block.is_a?(BlockArgumentNode)
+            arguments << block
+            block = nil
+          end
+
+          visit_block(node, s(node, :super).concat(visit_all(arguments)), block)
+        end
+
+        # :foo
+        # ^^^^
+        def visit_symbol_node(node)
+          node.value == "!@" ? s(node, :lit, :"!@") : s(node, :lit, node.unescaped.to_sym)
+        end
+
+        # true
+        # ^^^^
+        def visit_true_node(node)
+          s(node, :true)
+        end
+
+        # undef foo
+        # ^^^^^^^^^
+        def visit_undef_node(node)
+          names = node.names.map { |name| s(node, :undef, visit(name)) }
+          names.length == 1 ? names.first : s(node, :block).concat(names)
+        end
+
+        # unless foo; bar end
+        # ^^^^^^^^^^^^^^^^^^^
+        #
+        # bar unless foo
+        # ^^^^^^^^^^^^^^
+        def visit_unless_node(node)
+          s(node, :if, visit(node.predicate), visit(node.else_clause), visit(node.statements))
+        end
+
+        # until foo; bar end
+        # ^^^^^^^^^^^^^^^^^
+        #
+        # bar until foo
+        # ^^^^^^^^^^^^^
+        def visit_until_node(node)
+          s(node, :until, visit(node.predicate), visit(node.statements), !node.begin_modifier?)
+        end
+
+        # case foo; when bar; end
+        #           ^^^^^^^^^^^^^
+        def visit_when_node(node)
+          s(node, :when, s(node, :array).concat(visit_all(node.conditions))).concat(node.statements.nil? ? [nil] : visit_all(node.statements.body))
+        end
+
+        # while foo; bar end
+        # ^^^^^^^^^^^^^^^^^^
+        #
+        # bar while foo
+        # ^^^^^^^^^^^^^
+        def visit_while_node(node)
+          s(node, :while, visit(node.predicate), visit(node.statements), !node.begin_modifier?)
+        end
+
+        # `foo`
+        # ^^^^^
+        def visit_x_string_node(node)
+          result = s(node, :xstr, node.unescaped)
+
+          if node.heredoc?
+            result.line = node.content_loc.start_line
+            result.line_max = node.content_loc.end_line
+          end
+
+          result
+        end
+
+        # yield
+        # ^^^^^
+        #
+        # yield 1
+        # ^^^^^^^
+        def visit_yield_node(node)
+          s(node, :yield).concat(visit_all(node.arguments&.arguments || []))
+        end
+
+        private
+
+        # Attach prism comments to the given sexp.
+        def attach_comments(sexp, node)
+          return unless node.comments
+          return if node.comments.empty?
+
+          extra = node.location.start_line - node.comments.last.location.start_line
+          comments = node.comments.map(&:slice)
+          comments.concat([nil] * [0, extra].max)
+          sexp.comments = comments.join("\n")
+        end
+
+        # Create a new compiler with the given options.
+        def copy_compiler(in_def: self.in_def, in_pattern: self.in_pattern)
+          Compiler.new(file, in_def: in_def, in_pattern: in_pattern)
+        end
+
+        # Create a new Sexp object from the given prism node and arguments.
+        def s(node, *arguments)
+          result = Sexp.new(*arguments)
+          result.file = file
+          result.line = node.location.start_line
+          result.line_max = node.location.end_line
+          result
+        end
+
+        # Visit a block node, which will modify the AST by wrapping the given
+        # visited node in an iter node.
+        def visit_block(node, sexp, block)
+          if block.nil?
+            sexp
+          else
+            parameters =
+              case block.parameters
+              when nil, ItParametersNode, NumberedParametersNode
+                0
+              else
+                visit(block.parameters)
+              end
+
+            if block.body.nil?
+              s(node, :iter, sexp, parameters)
+            else
+              s(node, :iter, sexp, parameters, visit(block.body))
+            end
+          end
+        end
+
+        # Pattern constants get wrapped in another layer of :const.
+        def visit_pattern_constant(node)
+          case node
+          when nil
+            # nothing
+          when ConstantReadNode
+            visit(node)
+          else
+            s(node, :const, visit(node))
+          end
+        end
+
+        # Visit the value of a write, which will be on the right-hand side of
+        # a write operator. Because implicit arrays can have splats, those could
+        # potentially be wrapped in an svalue node.
+        def visit_write_value(node)
+          if node.is_a?(ArrayNode) && node.opening_loc.nil?
+            if node.elements.length == 1 && node.elements.first.is_a?(SplatNode)
+              s(node, :svalue, visit(node.elements.first))
+            else
+              s(node, :svalue, visit(node))
+            end
+          else
+            visit(node)
+          end
+        end
+      end
+
+      private_constant :Compiler
+
+      # Parse the given source and translate it into the seattlerb/ruby_parser
+      # gem's Sexp format.
+      def parse(source, filepath = "(string)")
+        translate(Prism.parse(source, filepath: filepath, partial_script: true), filepath)
+      end
+
+      # Parse the given file and translate it into the seattlerb/ruby_parser
+      # gem's Sexp format.
+      def parse_file(filepath)
+        translate(Prism.parse_file(filepath, partial_script: true), filepath)
+      end
+
+      # Parse the give file and translate it into the
+      # seattlerb/ruby_parser gem's Sexp format. This method is
+      # provided for API compatibility to RubyParser and takes an
+      # optional +timeout+ argument.
+      def process(ruby, file = "(string)", timeout = nil)
+        Timeout.timeout(timeout) { parse(ruby, file) }
+      end
+
+      class << self
+        # Parse the given source and translate it into the seattlerb/ruby_parser
+        # gem's Sexp format.
+        def parse(source, filepath = "(string)")
+          new.parse(source, filepath)
+        end
+
+        # Parse the given file and translate it into the seattlerb/ruby_parser
+        # gem's Sexp format.
+        def parse_file(filepath)
+          new.parse_file(filepath)
+        end
+      end
+
+      private
+
+      # Translate the given parse result and filepath into the
+      # seattlerb/ruby_parser gem's Sexp format.
+      def translate(result, filepath)
+        if result.failure?
+          error = result.errors.first
+          raise ::RubyParser::SyntaxError, "#{filepath}:#{error.location.start_line} :: #{error.message}"
+        end
+
+        result.attach_comments!
+        result.value.accept(Compiler.new(filepath))
+      end
+    end
+  end
+end
diff --git a/lib/profile.rb b/lib/profile.rb
deleted file mode 100644
index 2aeecce908..0000000000
--- a/lib/profile.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-require 'profiler'
-
-RubyVM::InstructionSequence.compile_option = {
-  :trace_instruction => true,
-  :specialized_instruction => false
-}
-END {
-  Profiler__::print_profile(STDERR)
-}
-Profiler__::start_profile
diff --git a/lib/profiler.rb b/lib/profiler.rb
deleted file mode 100644
index a4b8889093..0000000000
--- a/lib/profiler.rb
+++ /dev/null
@@ -1,59 +0,0 @@
-module Profiler__
-  # internal values
-  @@start = @@stack = @@map = nil
-  PROFILE_PROC = proc{|event, file, line, id, binding, klass|
-    case event
-    when "call", "c-call"
-      now = Process.times[0]
-      @@stack.push [now, 0.0]
-    when "return", "c-return"
-      now = Process.times[0]
-      key = [klass, id]
-      if tick = @@stack.pop
-        data = (@@map[key] ||= [0, 0.0, 0.0, key])
-        data[0] += 1
-        cost = now - tick[0]
-        data[1] += cost
-        data[2] += cost - tick[1]
-        @@stack[-1][1] += cost if @@stack[-1]
-      end
-    end
-  }
-module_function
-  def start_profile
-    @@start = Process.times[0]
-    @@stack = []
-    @@map = {}
-    set_trace_func PROFILE_PROC
-  end
-  def stop_profile
-    set_trace_func nil
-  end
-  def print_profile(f)
-    stop_profile
-    total = Process.times[0] - @@start
-    if total == 0 then total = 0.01 end
-    data = @@map.values
-    data = data.sort_by{|x| -x[2]}
-    sum = 0
-    f.printf "  %%   cumulative   self              self     total\n"
-    f.printf " time   seconds   seconds    calls  ms/call  ms/call  name\n"
-    for d in data
-      sum += d[2]
-      f.printf "%6.2f %8.2f  %8.2f %8d ", d[2]/total*100, sum, d[2], d[0]
-      f.printf "%8.2f %8.2f  %s\n", d[2]*1000/d[0], d[1]*1000/d[0], get_name(*d[3])
-    end
-    f.printf "%6.2f %8.2f  %8.2f %8d ", 0.0, total, 0.0, 1     # ???
-    f.printf "%8.2f %8.2f  %s\n", 0.0, total*1000, "#toplevel" # ???
-  end
-  def get_name(klass, id)
-    name = klass.to_s || ""
-    if klass.kind_of? Class
-      name += "#"
-    else
-      name += "."
-    end
-    name + id.id2name
-  end
-  private :get_name
-end
diff --git a/lib/pstore.rb b/lib/pstore.rb
deleted file mode 100644
index 429d7e5c7d..0000000000
--- a/lib/pstore.rb
+++ /dev/null
@@ -1,532 +0,0 @@
-# = PStore -- Transactional File Storage for Ruby Objects
-#
-# pstore.rb -
-#   originally by matz
-#   documentation by Kev Jackson and James Edward Gray II
-#   improved by Hongli Lai
-#
-# See PStore for documentation.
-
-
-require "fileutils"
-require "digest/md5"
-require "thread"
-
-#
-# PStore implements a file based persistence mechanism based on a Hash.  User
-# code can store hierarchies of Ruby objects (values) into the data store file
-# by name (keys).  An object hierarchy may be just a single object.  User code
-# may later read values back from the data store or even update data, as needed.
-#
-# The transactional behavior ensures that any changes succeed or fail together.
-# This can be used to ensure that the data store is not left in a transitory
-# state, where some values were updated but others were not.
-#
-# Behind the scenes, Ruby objects are stored to the data store file with
-# Marshal.  That carries the usual limitations.  Proc objects cannot be
-# marshalled, for example.
-#
-# == Usage example:
-#
-#  require "pstore"
-#
-#  # a mock wiki object...
-#  class WikiPage
-#    def initialize( page_name, author, contents )
-#      @page_name = page_name
-#      @revisions = Array.new
-#
-#      add_revision(author, contents)
-#    end
-#
-#    attr_reader :page_name
-#
-#    def add_revision( author, contents )
-#      @revisions << { :created  => Time.now,
-#                      :author   => author,
-#                      :contents => contents }
-#    end
-#
-#    def wiki_page_references
-#      [@page_name] + @revisions.last[:contents].scan(/\b(?:[A-Z]+[a-z]+){2,}/)
-#    end
-#
-#    # ...
-#  end
-#
-#  # create a new page...
-#  home_page = WikiPage.new( "HomePage", "James Edward Gray II",
-#                            "A page about the JoysOfDocumentation..." )
-#
-#  # then we want to update page data and the index together, or not at all...
-#  wiki = PStore.new("wiki_pages.pstore")
-#  wiki.transaction do  # begin transaction; do all of this or none of it
-#    # store page...
-#    wiki[home_page.page_name] = home_page
-#    # ensure that an index has been created...
-#    wiki[:wiki_index] ||= Array.new
-#    # update wiki index...
-#    wiki[:wiki_index].push(*home_page.wiki_page_references)
-#  end                   # commit changes to wiki data store file
-#
-#  ### Some time later... ###
-#
-#  # read wiki data...
-#  wiki.transaction(true) do  # begin read-only transaction, no changes allowed
-#    wiki.roots.each do |data_root_name|
-#      p data_root_name
-#      p wiki[data_root_name]
-#    end
-#  end
-#
-# == Transaction modes
-#
-# By default, file integrity is only ensured as long as the operating system
-# (and the underlying hardware) doesn't raise any unexpected I/O errors. If an
-# I/O error occurs while PStore is writing to its file, then the file will
-# become corrupted.
-#
-# You can prevent this by setting <em>pstore.ultra_safe = true</em>.
-# However, this results in a minor performance loss, and only works on platforms
-# that support atomic file renames. Please consult the documentation for
-# +ultra_safe+ for details.
-#
-# Needless to say, if you're storing valuable data with PStore, then you should
-# backup the PStore files from time to time.
-class PStore
-  RDWR_ACCESS = {mode: IO::RDWR | IO::CREAT | IO::BINARY, encoding: Encoding::ASCII_8BIT}.freeze
-  RD_ACCESS = {mode: IO::RDONLY | IO::BINARY, encoding: Encoding::ASCII_8BIT}.freeze
-  WR_ACCESS = {mode: IO::WRONLY | IO::CREAT | IO::TRUNC | IO::BINARY, encoding: Encoding::ASCII_8BIT}.freeze
-
-  # The error type thrown by all PStore methods.
-  class Error < StandardError
-  end
-
-  # Whether PStore should do its best to prevent file corruptions, even when under
-  # unlikely-to-occur error conditions such as out-of-space conditions and other
-  # unusual OS filesystem errors. Setting this flag comes at the price in the form
-  # of a performance loss.
-  #
-  # This flag only has effect on platforms on which file renames are atomic (e.g.
-  # all POSIX platforms: Linux, MacOS X, FreeBSD, etc). The default value is false.
-  attr_accessor :ultra_safe
-
-  #
-  # To construct a PStore object, pass in the _file_ path where you would like
-  # the data to be stored.
-  #
-  # PStore objects are always reentrant. But if _thread_safe_ is set to true,
-  # then it will become thread-safe at the cost of a minor performance hit.
-  #
-  def initialize(file, thread_safe = false)
-    dir = File::dirname(file)
-    unless File::directory? dir
-      raise PStore::Error, format("directory %s does not exist", dir)
-    end
-    if File::exist? file and not File::readable? file
-      raise PStore::Error, format("file %s not readable", file)
-    end
-    @filename = file
-    @abort = false
-    @ultra_safe = false
-    @thread_safe = thread_safe
-    @lock = Mutex.new
-  end
-
-  # Raises PStore::Error if the calling code is not in a PStore#transaction.
-  def in_transaction
-    raise PStore::Error, "not in transaction" unless @lock.locked?
-  end
-  #
-  # Raises PStore::Error if the calling code is not in a PStore#transaction or
-  # if the code is in a read-only PStore#transaction.
-  #
-  def in_transaction_wr()
-    in_transaction()
-    raise PStore::Error, "in read-only transaction" if @rdonly
-  end
-  private :in_transaction, :in_transaction_wr
-
-  #
-  # Retrieves a value from the PStore file data, by _name_.  The hierarchy of
-  # Ruby objects stored under that root _name_ will be returned.
-  #
-  # *WARNING*:  This method is only valid in a PStore#transaction.  It will
-  # raise PStore::Error if called at any other time.
-  #
-  def [](name)
-    in_transaction
-    @table[name]
-  end
-  #
-  # This method is just like PStore#[], save that you may also provide a
-  # _default_ value for the object.  In the event the specified _name_ is not
-  # found in the data store, your _default_ will be returned instead.  If you do
-  # not specify a default, PStore::Error will be raised if the object is not
-  # found.
-  #
-  # *WARNING*:  This method is only valid in a PStore#transaction.  It will
-  # raise PStore::Error if called at any other time.
-  #
-  def fetch(name, default=PStore::Error)
-    in_transaction
-    unless @table.key? name
-      if default == PStore::Error
-        raise PStore::Error, format("undefined root name `%s'", name)
-      else
-        return default
-      end
-    end
-    @table[name]
-  end
-  #
-  # Stores an individual Ruby object or a hierarchy of Ruby objects in the data
-  # store file under the root _name_.  Assigning to a _name_ already in the data
-  # store clobbers the old data.
-  #
-  # == Example:
-  #
-  #  require "pstore"
-  #
-  #  store = PStore.new("data_file.pstore")
-  #  store.transaction do  # begin transaction
-  #    # load some data into the store...
-  #    store[:single_object] = "My data..."
-  #    store[:obj_heirarchy] = { "Kev Jackson" => ["rational.rb", "pstore.rb"],
-  #                              "James Gray"  => ["erb.rb", "pstore.rb"] }
-  #  end                   # commit changes to data store file
-  #
-  # *WARNING*:  This method is only valid in a PStore#transaction and it cannot
-  # be read-only.  It will raise PStore::Error if called at any other time.
-  #
-  def []=(name, value)
-    in_transaction_wr()
-    @table[name] = value
-  end
-  #
-  # Removes an object hierarchy from the data store, by _name_.
-  #
-  # *WARNING*:  This method is only valid in a PStore#transaction and it cannot
-  # be read-only.  It will raise PStore::Error if called at any other time.
-  #
-  def delete(name)
-    in_transaction_wr()
-    @table.delete name
-  end
-
-  #
-  # Returns the names of all object hierarchies currently in the store.
-  #
-  # *WARNING*:  This method is only valid in a PStore#transaction.  It will
-  # raise PStore::Error if called at any other time.
-  #
-  def roots
-    in_transaction
-    @table.keys
-  end
-  #
-  # Returns true if the supplied _name_ is currently in the data store.
-  #
-  # *WARNING*:  This method is only valid in a PStore#transaction.  It will
-  # raise PStore::Error if called at any other time.
-  #
-  def root?(name)
-    in_transaction
-    @table.key? name
-  end
-  # Returns the path to the data store file.
-  def path
-    @filename
-  end
-
-  #
-  # Ends the current PStore#transaction, committing any changes to the data
-  # store immediately.
-  #
-  # == Example:
-  #
-  #  require "pstore"
-  #
-  #  store = PStore.new("data_file.pstore")
-  #  store.transaction do  # begin transaction
-  #    # load some data into the store...
-  #    store[:one] = 1
-  #    store[:two] = 2
-  #
-  #    store.commit        # end transaction here, committing changes
-  #
-  #    store[:three] = 3   # this change is never reached
-  #  end
-  #
-  # *WARNING*:  This method is only valid in a PStore#transaction.  It will
-  # raise PStore::Error if called at any other time.
-  #
-  def commit
-    in_transaction
-    @abort = false
-    throw :pstore_abort_transaction
-  end
-  #
-  # Ends the current PStore#transaction, discarding any changes to the data
-  # store.
-  #
-  # == Example:
-  #
-  #  require "pstore"
-  #
-  #  store = PStore.new("data_file.pstore")
-  #  store.transaction do  # begin transaction
-  #    store[:one] = 1     # this change is not applied, see below...
-  #    store[:two] = 2     # this change is not applied, see below...
-  #
-  #    store.abort         # end transaction here, discard all changes
-  #
-  #    store[:three] = 3   # this change is never reached
-  #  end
-  #
-  # *WARNING*:  This method is only valid in a PStore#transaction.  It will
-  # raise PStore::Error if called at any other time.
-  #
-  def abort
-    in_transaction
-    @abort = true
-    throw :pstore_abort_transaction
-  end
-
-  #
-  # Opens a new transaction for the data store.  Code executed inside a block
-  # passed to this method may read and write data to and from the data store
-  # file.
-  #
-  # At the end of the block, changes are committed to the data store
-  # automatically.  You may exit the transaction early with a call to either
-  # PStore#commit or PStore#abort.  See those methods for details about how
-  # changes are handled.  Raising an uncaught Exception in the block is
-  # equivalent to calling PStore#abort.
-  #
-  # If _read_only_ is set to +true+, you will only be allowed to read from the
-  # data store during the transaction and any attempts to change the data will
-  # raise a PStore::Error.
-  #
-  # Note that PStore does not support nested transactions.
-  #
-  def transaction(read_only = false, &block)  # :yields:  pstore
-    value = nil
-    raise PStore::Error, "nested transaction" if !@thread_safe && @lock.locked?
-    @lock.synchronize do
-      @rdonly = read_only
-      @abort = false
-      file = open_and_lock_file(@filename, read_only)
-      if file
-        begin
-          @table, checksum, original_data_size = load_data(file, read_only)
-
-          catch(:pstore_abort_transaction) do
-            value = yield(self)
-          end
-
-          if !@abort && !read_only
-            save_data(checksum, original_data_size, file)
-          end
-        ensure
-          file.close if !file.closed?
-        end
-      else
-        # This can only occur if read_only == true.
-        @table = {}
-        catch(:pstore_abort_transaction) do
-          value = yield(self)
-        end
-      end
-    end
-    value
-  rescue ThreadError
-    raise PStore::Error, "nested transaction"
-  end
-
-  private
-  # Constant for relieving Ruby's garbage collector.
-  EMPTY_STRING = ""
-  EMPTY_MARSHAL_DATA = Marshal.dump({})
-  EMPTY_MARSHAL_CHECKSUM = Digest::MD5.digest(EMPTY_MARSHAL_DATA)
-
-  #
-  # Open the specified filename (either in read-only mode or in
-  # read-write mode) and lock it for reading or writing.
-  #
-  # The opened File object will be returned. If _read_only_ is true,
-  # and the file does not exist, then nil will be returned.
-  #
-  # All exceptions are propagated.
-  #
-  def open_and_lock_file(filename, read_only)
-    if read_only
-      begin
-        file = File.new(filename, RD_ACCESS)
-        begin
-          file.flock(File::LOCK_SH)
-          return file
-        rescue
-          file.close
-          raise
-        end
-      rescue Errno::ENOENT
-        return nil
-      end
-    else
-      file = File.new(filename, RDWR_ACCESS)
-      file.flock(File::LOCK_EX)
-      return file
-    end
-  end
-
-  # Load the given PStore file.
-  # If +read_only+ is true, the unmarshalled Hash will be returned.
-  # If +read_only+ is false, a 3-tuple will be returned: the unmarshalled
-  # Hash, an MD5 checksum of the data, and the size of the data.
-  def load_data(file, read_only)
-    if read_only
-      begin
-        table = load(file)
-        if !table.is_a?(Hash)
-          raise Error, "PStore file seems to be corrupted."
-        end
-      rescue EOFError
-        # This seems to be a newly-created file.
-        table = {}
-      end
-      table
-    else
-      data = file.read
-      if data.empty?
-        # This seems to be a newly-created file.
-        table = {}
-        checksum = empty_marshal_checksum
-        size = empty_marshal_data.size
-      else
-        table = load(data)
-        checksum = Digest::MD5.digest(data)
-        size = data.size
-        if !table.is_a?(Hash)
-          raise Error, "PStore file seems to be corrupted."
-        end
-      end
-      data.replace(EMPTY_STRING)
-      [table, checksum, size]
-    end
-  end
-
-  def on_windows?
-    is_windows = RUBY_PLATFORM =~ /mswin/  ||
-                 RUBY_PLATFORM =~ /mingw/  ||
-                 RUBY_PLATFORM =~ /bccwin/ ||
-                 RUBY_PLATFORM =~ /wince/
-    self.class.__send__(:define_method, :on_windows?) do
-      is_windows
-    end
-    is_windows
-  end
-
-  # Check whether Marshal.dump supports the 'canonical' option. This option
-  # makes sure that Marshal.dump always dumps data structures in the same order.
-  # This is important because otherwise, the checksums that we generate may differ.
-  def marshal_dump_supports_canonical_option?
-    begin
-      Marshal.dump(nil, -1, true)
-      result = true
-    rescue
-      result = false
-    end
-    self.class.instance_method(:marshal_dump_supports_canonical_option?)
-    self.class.__send__(:define_method, :marshal_dump_supports_canonical_option?) do
-      result
-    end
-    result
-  end
-
-  def save_data(original_checksum, original_file_size, file)
-    # We only want to save the new data if the size or checksum has changed.
-    # This results in less filesystem calls, which is good for performance.
-    if marshal_dump_supports_canonical_option?
-      new_data = Marshal.dump(@table, -1, true)
-    else
-      new_data = dump(@table)
-    end
-    new_checksum = Digest::MD5.digest(new_data)
-
-    if new_data.size != original_file_size || new_checksum != original_checksum
-      if @ultra_safe && !on_windows?
-        # Windows doesn't support atomic file renames.
-        save_data_with_atomic_file_rename_strategy(new_data, file)
-      else
-        save_data_with_fast_strategy(new_data, file)
-      end
-    end
-
-    new_data.replace(EMPTY_STRING)
-  end
-
-  def save_data_with_atomic_file_rename_strategy(data, file)
-    temp_filename = "#{@filename}.tmp.#{Process.pid}.#{rand 1000000}"
-    temp_file = File.new(temp_filename, WR_ACCESS)
-    begin
-      temp_file.flock(File::LOCK_EX)
-      temp_file.write(data)
-      temp_file.flush
-      File.rename(temp_filename, @filename)
-    rescue
-      File.unlink(temp_file) rescue nil
-      raise
-    ensure
-      temp_file.close
-    end
-  end
-
-  def save_data_with_fast_strategy(data, file)
-    file.rewind
-    file.truncate(0)
-    file.write(data)
-  end
-
-
-  # This method is just a wrapped around Marshal.dump
-  # to allow subclass overriding used in YAML::Store.
-  def dump(table)  # :nodoc:
-    Marshal::dump(table)
-  end
-
-  # This method is just a wrapped around Marshal.load.
-  # to allow subclass overriding used in YAML::Store.
-  def load(content)  # :nodoc:
-    Marshal::load(content)
-  end
-
-  def empty_marshal_data
-    EMPTY_MARSHAL_DATA
-  end
-  def empty_marshal_checksum
-    EMPTY_MARSHAL_CHECKSUM
-  end
-end
-
-# :enddoc:
-
-if __FILE__ == $0
-  db = PStore.new("/tmp/foo")
-  db.transaction do
-    p db.roots
-    ary = db["root"] = [1,2,3,4]
-    ary[1] = [1,1.5]
-  end
-
-  1000.times do
-    db.transaction do
-      db["root"][0] += 1
-      p db["root"][0]
-    end
-  end
-
-  db.transaction(true) do
-    p db["root"]
-  end
-end
diff --git a/lib/racc/parser.rb b/lib/racc/parser.rb
deleted file mode 100644
index 737b0fda5d..0000000000
--- a/lib/racc/parser.rb
+++ /dev/null
@@ -1,443 +0,0 @@
-#
-# $originalId: parser.rb,v 1.8 2006/07/06 11:42:07 aamine Exp $
-#
-# Copyright (c) 1999-2006 Minero Aoki
-#
-# This program is free software.
-# You can distribute/modify this program under the same terms of ruby.
-#
-# As a special exception, when this code is copied by Racc
-# into a Racc output file, you may use that output file
-# without restriction.
-#
-
-unless defined?(NotImplementedError)
-  NotImplementedError = NotImplementError
-end
-
-module Racc
-  class ParseError < StandardError; end
-end
-unless defined?(::ParseError)
-  ParseError = Racc::ParseError
-end
-
-module Racc
-
-  unless defined?(Racc_No_Extentions)
-    Racc_No_Extentions = false
-  end
-
-  class Parser
-
-    Racc_Runtime_Version = '1.4.6'
-    Racc_Runtime_Revision = %w$originalRevision: 1.8 $[1]
-
-    Racc_Runtime_Core_Version_R = '1.4.6'
-    Racc_Runtime_Core_Revision_R = %w$originalRevision: 1.8 $[1]
-    begin
-      require 'racc/cparse'
-    # Racc_Runtime_Core_Version_C  = (defined in extention)
-      Racc_Runtime_Core_Revision_C = Racc_Runtime_Core_Id_C.split[2]
-      unless new.respond_to?(:_racc_do_parse_c, true)
-        raise LoadError, 'old cparse.so'
-      end
-      if Racc_No_Extentions
-        raise LoadError, 'selecting ruby version of racc runtime core'
-      end
-
-      Racc_Main_Parsing_Routine    = :_racc_do_parse_c
-      Racc_YY_Parse_Method         = :_racc_yyparse_c
-      Racc_Runtime_Core_Version    = Racc_Runtime_Core_Version_C
-      Racc_Runtime_Core_Revision   = Racc_Runtime_Core_Revision_C
-      Racc_Runtime_Type            = 'c'
-    rescue LoadError
-      Racc_Main_Parsing_Routine    = :_racc_do_parse_rb
-      Racc_YY_Parse_Method         = :_racc_yyparse_rb
-      Racc_Runtime_Core_Version    = Racc_Runtime_Core_Version_R
-      Racc_Runtime_Core_Revision   = Racc_Runtime_Core_Revision_R
-      Racc_Runtime_Type            = 'ruby'
-    end
-
-    def Parser.racc_runtime_type
-      Racc_Runtime_Type
-    end
-
-    private
-
-    def _racc_setup
-      @yydebug = false unless self.class::Racc_debug_parser
-      @yydebug = false unless defined?(@yydebug)
-      if @yydebug
-        @racc_debug_out = $stderr unless defined?(@racc_debug_out)
-        @racc_debug_out ||= $stderr
-      end
-      arg = self.class::Racc_arg
-      arg[13] = true if arg.size < 14
-      arg
-    end
-
-    def _racc_init_sysvars
-      @racc_state  = [0]
-      @racc_tstack = []
-      @racc_vstack = []
-
-      @racc_t = nil
-      @racc_val = nil
-
-      @racc_read_next = true
-
-      @racc_user_yyerror = false
-      @racc_error_status = 0
-    end
-
-    ###
-    ### do_parse
-    ###
-
-    class_eval %{
-    def do_parse
-      #{Racc_Main_Parsing_Routine}(_racc_setup(), false)
-    end
-    }
-
-    def next_token
-      raise NotImplementedError, "#{self.class}\#next_token is not defined"
-    end
-
-    def _racc_do_parse_rb(arg, in_debug)
-      action_table, action_check, action_default, action_pointer,
-      _,            _,            _,              _,
-      _,            _,            token_table,    _,
-      _,            _,            * = arg
-
-      _racc_init_sysvars
-      tok = act = i = nil
-
-      catch(:racc_end_parse) {
-        while true
-          if i = action_pointer[@racc_state[-1]]
-            if @racc_read_next
-              if @racc_t != 0   # not EOF
-                tok, @racc_val = next_token()
-                unless tok      # EOF
-                  @racc_t = 0
-                else
-                  @racc_t = (token_table[tok] or 1)   # error token
-                end
-                racc_read_token(@racc_t, tok, @racc_val) if @yydebug
-                @racc_read_next = false
-              end
-            end
-            i += @racc_t
-            unless i >= 0 and
-                   act = action_table[i] and
-                   action_check[i] == @racc_state[-1]
-              act = action_default[@racc_state[-1]]
-            end
-          else
-            act = action_default[@racc_state[-1]]
-          end
-          while act = _racc_evalact(act, arg)
-            ;
-          end
-        end
-      }
-    end
-
-    ###
-    ### yyparse
-    ###
-
-    class_eval %{
-    def yyparse(recv, mid)
-      #{Racc_YY_Parse_Method}(recv, mid, _racc_setup(), true)
-    end
-    }
-
-    def _racc_yyparse_rb(recv, mid, arg, c_debug)
-      action_table, action_check, action_default, action_pointer,
-      _,             _,            _,              _,
-      _,            _,            token_table,    _,
-      _,            _,            * = arg
-
-      _racc_init_sysvars
-      act = nil
-      i = nil
-
-      catch(:racc_end_parse) {
-        until i = action_pointer[@racc_state[-1]]
-          while act = _racc_evalact(action_default[@racc_state[-1]], arg)
-            ;
-          end
-        end
-        recv.__send__(mid) do |tok, val|
-          unless tok
-            @racc_t = 0
-          else
-            @racc_t = (token_table[tok] or 1)   # error token
-          end
-          @racc_val = val
-          @racc_read_next = false
-
-          i += @racc_t
-          unless i >= 0 and
-                 act = action_table[i] and
-                 action_check[i] == @racc_state[-1]
-            act = action_default[@racc_state[-1]]
-          end
-          while act = _racc_evalact(act, arg)
-            ;
-          end
-
-          while not(i = action_pointer[@racc_state[-1]]) or
-                not @racc_read_next or
-                @racc_t == 0   # $
-            unless i and i += @racc_t and
-                   i >= 0 and
-                   act = action_table[i] and
-                   action_check[i] == @racc_state[-1]
-              act = action_default[@racc_state[-1]]
-            end
-            while act = _racc_evalact(act, arg)
-              ;
-            end
-          end
-        end
-      }
-    end
-
-    ###
-    ### common
-    ###
-
-    def _racc_evalact(act, arg)
-      action_table, action_check, _, action_pointer,
-      _,   _, _, _,
-      _,   _, _, shift_n,  reduce_n,
-      _,   _, * = arg
-      nerr = 0   # tmp
-
-      if act > 0 and act < shift_n
-        #
-        # shift
-        #
-        if @racc_error_status > 0
-          @racc_error_status -= 1 unless @racc_t == 1   # error token
-        end
-        @racc_vstack.push @racc_val
-        @racc_state.push act
-        @racc_read_next = true
-        if @yydebug
-          @racc_tstack.push @racc_t
-          racc_shift @racc_t, @racc_tstack, @racc_vstack
-        end
-
-      elsif act < 0 and act > -reduce_n
-        #
-        # reduce
-        #
-        code = catch(:racc_jump) {
-          @racc_state.push _racc_do_reduce(arg, act)
-          false
-        }
-        if code
-          case code
-          when 1 # yyerror
-            @racc_user_yyerror = true   # user_yyerror
-            return -reduce_n
-          when 2 # yyaccept
-            return shift_n
-          else
-            raise '[Racc Bug] unknown jump code'
-          end
-        end
-
-      elsif act == shift_n
-        #
-        # accept
-        #
-        racc_accept if @yydebug
-        throw :racc_end_parse, @racc_vstack[0]
-
-      elsif act == -reduce_n
-        #
-        # error
-        #
-        case @racc_error_status
-        when 0
-          unless arg[21]    # user_yyerror
-            nerr += 1
-            on_error @racc_t, @racc_val, @racc_vstack
-          end
-        when 3
-          if @racc_t == 0   # is $
-            throw :racc_end_parse, nil
-          end
-          @racc_read_next = true
-        end
-        @racc_user_yyerror = false
-        @racc_error_status = 3
-        while true
-          if i = action_pointer[@racc_state[-1]]
-            i += 1   # error token
-            if  i >= 0 and
-                (act = action_table[i]) and
-                action_check[i] == @racc_state[-1]
-              break
-            end
-          end
-          throw :racc_end_parse, nil if @racc_state.size <= 1
-          @racc_state.pop
-          @racc_vstack.pop
-          if @yydebug
-            @racc_tstack.pop
-            racc_e_pop @racc_state, @racc_tstack, @racc_vstack
-          end
-        end
-        return act
-
-      else
-        raise "[Racc Bug] unknown action #{act.inspect}"
-      end
-
-      racc_next_state(@racc_state[-1], @racc_state) if @yydebug
-
-      nil
-    end
-
-    def _racc_do_reduce(arg, act)
-      _, _, _, _,
-      goto_table,   goto_check,   goto_default,   goto_pointer,
-      nt_base,      reduce_table, _,    _,
-      _,     use_result,   * = arg
-      state = @racc_state
-      vstack = @racc_vstack
-      tstack = @racc_tstack
-
-      i = act * -3
-      len       = reduce_table[i]
-      reduce_to = reduce_table[i+1]
-      method_id = reduce_table[i+2]
-      void_array = []
-
-      tmp_t = tstack[-len, len] if @yydebug
-      tmp_v = vstack[-len, len]
-      tstack[-len, len] = void_array if @yydebug
-      vstack[-len, len] = void_array
-      state[-len, len]  = void_array
-
-      # tstack must be updated AFTER method call
-      if use_result
-        vstack.push __send__(method_id, tmp_v, vstack, tmp_v[0])
-      else
-        vstack.push __send__(method_id, tmp_v, vstack)
-      end
-      tstack.push reduce_to
-
-      racc_reduce(tmp_t, reduce_to, tstack, vstack) if @yydebug
-
-      k1 = reduce_to - nt_base
-      if i = goto_pointer[k1]
-        i += state[-1]
-        if i >= 0 and (curstate = goto_table[i]) and goto_check[i] == k1
-          return curstate
-        end
-      end
-      goto_default[k1]
-    end
-
-    def on_error(t, val, vstack)
-      raise ParseError, sprintf("\nparse error on value %s (%s)",
-                                val.inspect, token_to_str(t) || '?')
-    end
-
-    def yyerror
-      throw :racc_jump, 1
-    end
-
-    def yyaccept
-      throw :racc_jump, 2
-    end
-
-    def yyerrok
-      @racc_error_status = 0
-    end
-
-    #
-    # for debugging output
-    #
-
-    def racc_read_token(t, tok, val)
-      @racc_debug_out.print 'read    '
-      @racc_debug_out.print tok.inspect, '(', racc_token2str(t), ') '
-      @racc_debug_out.puts val.inspect
-      @racc_debug_out.puts
-    end
-
-    def racc_shift(tok, tstack, vstack)
-      @racc_debug_out.puts "shift   #{racc_token2str tok}"
-      racc_print_stacks tstack, vstack
-      @racc_debug_out.puts
-    end
-
-    def racc_reduce(toks, sim, tstack, vstack)
-      out = @racc_debug_out
-      out.print 'reduce '
-      if toks.empty?
-        out.print ' <none>'
-      else
-        toks.each {|t| out.print ' ', racc_token2str(t) }
-      end
-      out.puts " --> #{racc_token2str(sim)}"
-
-      racc_print_stacks tstack, vstack
-      @racc_debug_out.puts
-    end
-
-    def racc_accept
-      @racc_debug_out.puts 'accept'
-      @racc_debug_out.puts
-    end
-
-    def racc_e_pop(state, tstack, vstack)
-      @racc_debug_out.puts 'error recovering mode: pop token'
-      racc_print_states state
-      racc_print_stacks tstack, vstack
-      @racc_debug_out.puts
-    end
-
-    def racc_next_state(curstate, state)
-      @racc_debug_out.puts  "goto    #{curstate}"
-      racc_print_states state
-      @racc_debug_out.puts
-    end
-
-    def racc_print_stacks(t, v)
-      out = @racc_debug_out
-      out.print '        ['
-      t.each_index do |i|
-        out.print ' (', racc_token2str(t[i]), ' ', v[i].inspect, ')'
-      end
-      out.puts ' ]'
-    end
-
-    def racc_print_states(s)
-      out = @racc_debug_out
-      out.print '        ['
-      s.each {|st| out.print ' ', st }
-      out.puts ' ]'
-    end
-
-    def racc_token2str(tok)
-      self.class::Racc_token_to_s_table[tok] or
-          raise "[Racc Bug] can't convert token #{tok} to string"
-    end
-
-    def token_to_str(t)
-      self.class::Racc_token_to_s_table[t]
-    end
-
-  end
-
-end
diff --git a/lib/rake.rb b/lib/rake.rb
deleted file mode 100644
index fc1a6a5165..0000000000
--- a/lib/rake.rb
+++ /dev/null
@@ -1,69 +0,0 @@
-#--
-
-# Copyright 2003-2010 by Jim Weirich (jim.weirich@gmail.com)
-#
-# Permission is hereby granted, free of charge, to any person obtaining a copy
-# of this software and associated documentation files (the "Software"), to
-# deal in the Software without restriction, including without limitation the
-# rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
-# sell copies of the Software, and to permit persons to whom the Software is
-# furnished to do so, subject to the following conditions:
-#
-# The above copyright notice and this permission notice shall be included in
-# all copies or substantial portions of the Software.
-#
-# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
-# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
-# IN THE SOFTWARE.
-#++
-
-require 'rake/version'
-
-# :stopdoc:
-RAKEVERSION = Rake::VERSION
-# :startdoc:
-
-require 'rbconfig'
-require 'fileutils'
-require 'singleton'
-require 'monitor'
-require 'optparse'
-require 'ostruct'
-
-require 'rake/ext/module'
-require 'rake/ext/string'
-require 'rake/ext/time'
-
-require 'rake/win32'
-
-require 'rake/task_argument_error'
-require 'rake/rule_recursion_overflow_error'
-require 'rake/rake_module'
-require 'rake/pseudo_status'
-require 'rake/task_arguments'
-require 'rake/invocation_chain'
-require 'rake/task'
-require 'rake/file_task'
-require 'rake/file_creation_task'
-require 'rake/multi_task'
-require 'rake/dsl_definition'
-require 'rake/file_utils_ext'
-require 'rake/file_list'
-require 'rake/default_loader'
-require 'rake/early_time'
-require 'rake/name_space'
-require 'rake/task_manager'
-require 'rake/application'
-
-$trace = false
-
-# :stopdoc:
-#
-# Some top level Constants.
-
-FileList = Rake::FileList
-RakeFileUtils = Rake::FileUtilsExt
diff --git a/lib/rake/alt_system.rb b/lib/rake/alt_system.rb
deleted file mode 100644
index 05af19863a..0000000000
--- a/lib/rake/alt_system.rb
+++ /dev/null
@@ -1,109 +0,0 @@
-#
-# Copyright (c) 2008 James M. Lawrence
-#
-# Permission is hereby granted, free of charge, to any person
-# obtaining a copy of this software and associated documentation files
-# (the "Software"), to deal in the Software without restriction,
-# including without limitation the rights to use, copy, modify, merge,
-# publish, distribute, sublicense, and/or sell copies of the Software,
-# and to permit persons to whom the Software is furnished to do so,
-# subject to the following conditions:
-#
-# The above copyright notice and this permission notice shall be
-# included in all copies or substantial portions of the Software.
-#
-# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
-# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
-# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
-# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
-# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-# SOFTWARE.
-#
-
-require 'rbconfig'
-
-#
-# Alternate implementations of system() and backticks `` on Windows
-# for ruby-1.8 and earlier.
-#
-module Rake::AltSystem
-  WINDOWS = RbConfig::CONFIG["host_os"] =~
-    %r!(msdos|mswin|djgpp|mingw|[Ww]indows)!
-
-  class << self
-    def define_module_function(name, &block)
-      define_method(name, &block)
-      module_function(name)
-    end
-  end
-
-  if WINDOWS and RUBY_VERSION < "1.9.0"
-    RUNNABLE_EXTS = %w[com exe bat cmd]
-    RUNNABLE_PATTERN = %r!\.(#{RUNNABLE_EXTS.join('|')})\Z!i
-
-    define_module_function :kernel_system, &Kernel.method(:system)
-    define_module_function :kernel_backticks, &Kernel.method(:'`')
-
-    module_function
-
-    def repair_command(cmd)
-      "call " + (
-        if cmd =~ %r!\A\s*\".*?\"!
-          # already quoted
-          cmd
-        elsif match = cmd.match(%r!\A\s*(\S+)!)
-          if match[1] =~ %r!/!
-            # avoid x/y.bat interpretation as x with option /y
-            %Q!"#{match[1]}"! + match.post_match
-          else
-            # a shell command will fail if quoted
-            cmd
-          end
-        else
-          # empty or whitespace
-          cmd
-        end
-      )
-    end
-
-    def find_runnable(file)
-      if file =~ RUNNABLE_PATTERN
-        file
-      else
-        RUNNABLE_EXTS.each { |ext|
-          if File.exist?(test = "#{file}.#{ext}")
-            return test
-          end
-        }
-        nil
-      end
-    end
-
-    def system(cmd, *args)
-      repaired = (
-        if args.empty?
-          [repair_command(cmd)]
-        elsif runnable = find_runnable(cmd)
-          [File.expand_path(runnable), *args]
-        else
-          # non-existent file
-          [cmd, *args]
-        end
-      )
-      kernel_system(*repaired)
-    end
-
-    def backticks(cmd)
-      kernel_backticks(repair_command(cmd))
-    end
-
-    define_module_function :'`', &method(:backticks)
-  else
-    # Non-Windows or ruby-1.9+: same as Kernel versions
-    define_module_function :system, &Kernel.method(:system)
-    define_module_function :backticks, &Kernel.method(:'`')
-    define_module_function :'`', &Kernel.method(:'`')
-  end
-end
diff --git a/lib/rake/application.rb b/lib/rake/application.rb
deleted file mode 100644
index 2079fb9be6..0000000000
--- a/lib/rake/application.rb
+++ /dev/null
@@ -1,595 +0,0 @@
-require 'shellwords'
-require 'optparse'
-
-require 'rake/task_manager'
-require 'rake/win32'
-
-module Rake
-
-  ######################################################################
-  # Rake main application object.  When invoking +rake+ from the
-  # command line, a Rake::Application object is created and run.
-  #
-  class Application
-    include TaskManager
-
-    # The name of the application (typically 'rake')
-    attr_reader :name
-
-    # The original directory where rake was invoked.
-    attr_reader :original_dir
-
-    # Name of the actual rakefile used.
-    attr_reader :rakefile
-
-    # Number of columns on the terminal
-    attr_accessor :terminal_columns
-
-    # List of the top level task names (task names from the command line).
-    attr_reader :top_level_tasks
-
-    DEFAULT_RAKEFILES = ['rakefile', 'Rakefile', 'rakefile.rb', 'Rakefile.rb'].freeze
-
-    # Initialize a Rake::Application object.
-    def initialize
-      super
-      @name = 'rake'
-      @rakefiles = DEFAULT_RAKEFILES.dup
-      @rakefile = nil
-      @pending_imports = []
-      @imported = []
-      @loaders = {}
-      @default_loader = Rake::DefaultLoader.new
-      @original_dir = Dir.pwd
-      @top_level_tasks = []
-      add_loader('rb', DefaultLoader.new)
-      add_loader('rf', DefaultLoader.new)
-      add_loader('rake', DefaultLoader.new)
-      @tty_output = STDOUT.tty?
-      @terminal_columns = ENV['RAKE_COLUMNS'].to_i
-    end
-
-    # Run the Rake application.  The run method performs the following
-    # three steps:
-    #
-    # * Initialize the command line options (+init+).
-    # * Define the tasks (+load_rakefile+).
-    # * Run the top level tasks (+run_tasks+).
-    #
-    # If you wish to build a custom rake command, you should call
-    # +init+ on your application.  Then define any tasks.  Finally,
-    # call +top_level+ to run your top level tasks.
-    def run
-      standard_exception_handling do
-        init
-        load_rakefile
-        top_level
-      end
-    end
-
-    # Initialize the command line parameters and app name.
-    def init(app_name='rake')
-      standard_exception_handling do
-        @name = app_name
-        handle_options
-        collect_tasks
-      end
-    end
-
-    # Find the rakefile and then load it and any pending imports.
-    def load_rakefile
-      standard_exception_handling do
-        raw_load_rakefile
-      end
-    end
-
-    # Run the top level tasks of a Rake application.
-    def top_level
-      standard_exception_handling do
-        if options.show_tasks
-          display_tasks_and_comments
-        elsif options.show_prereqs
-          display_prerequisites
-        else
-          top_level_tasks.each { |task_name| invoke_task(task_name) }
-        end
-      end
-    end
-
-    # Add a loader to handle imported files ending in the extension
-    # +ext+.
-    def add_loader(ext, loader)
-      ext = ".#{ext}" unless ext =~ /^\./
-      @loaders[ext] = loader
-    end
-
-    # Application options from the command line
-    def options
-      @options ||= OpenStruct.new
-    end
-
-    # private ----------------------------------------------------------------
-
-    def invoke_task(task_string)
-      name, args = parse_task_string(task_string)
-      t = self[name]
-      t.invoke(*args)
-    end
-
-    def parse_task_string(string)
-      if string =~ /^([^\[]+)(\[(.*)\])$/
-        name = $1
-        args = $3.split(/\s*,\s*/)
-      else
-        name = string
-        args = []
-      end
-      [name, args]
-    end
-
-    # Provide standard exception handling for the given block.
-    def standard_exception_handling
-      begin
-        yield
-      rescue SystemExit => ex
-        # Exit silently with current status
-        raise
-      rescue OptionParser::InvalidOption => ex
-        $stderr.puts ex.message
-        exit(false)
-      rescue Exception => ex
-        # Exit with error message
-        display_error_message(ex)
-        exit(false)
-      end
-    end
-
-    # Display the error message that caused the exception.
-    def display_error_message(ex)
-      $stderr.puts "#{name} aborted!"
-      $stderr.puts ex.message
-      if options.trace
-        $stderr.puts ex.backtrace.join("\n")
-      else
-        $stderr.puts rakefile_location(ex.backtrace)
-      end
-      $stderr.puts "Tasks: #{ex.chain}" if has_chain?(ex)
-      $stderr.puts "(See full trace by running task with --trace)" unless options.trace
-    end
-
-    # Warn about deprecated usage.
-    #
-    # Example:
-    #    Rake.application.deprecate("import", "Rake.import", caller.first)
-    #
-    def deprecate(old_usage, new_usage, call_site)
-      return if options.ignore_deprecate
-      $stderr.puts "WARNING: '#{old_usage}' is deprecated.  " +
-        "Please use '#{new_usage}' instead.\n" +
-        "    at #{call_site}"
-    end
-
-    # Does the exception have a task invocation chain?
-    def has_chain?(exception)
-      exception.respond_to?(:chain) && exception.chain
-    end
-    private :has_chain?
-
-    # True if one of the files in RAKEFILES is in the current directory.
-    # If a match is found, it is copied into @rakefile.
-    def have_rakefile
-      @rakefiles.each do |fn|
-        if File.exist?(fn)
-          others = Dir.glob(fn, File::FNM_CASEFOLD)
-          return others.size == 1 ? others.first : fn
-        elsif fn == ''
-          return fn
-        end
-      end
-      return nil
-    end
-
-    # True if we are outputting to TTY, false otherwise
-    def tty_output?
-      @tty_output
-    end
-
-    # Override the detected TTY output state (mostly for testing)
-    def tty_output=( tty_output_state )
-      @tty_output = tty_output_state
-    end
-
-    # We will truncate output if we are outputting to a TTY or if we've been
-    # given an explicit column width to honor
-    def truncate_output?
-      tty_output? || @terminal_columns.nonzero?
-    end
-
-    # Display the tasks and comments.
-    def display_tasks_and_comments
-      displayable_tasks = tasks.select { |t|
-        t.comment && t.name =~ options.show_task_pattern
-      }
-      case options.show_tasks
-      when :tasks
-        width = displayable_tasks.collect { |t| t.name_with_args.length }.max || 10
-        max_column = truncate_output? ? terminal_width - name.size - width - 7 : nil
-
-        displayable_tasks.each do |t|
-          printf "#{name} %-#{width}s  # %s\n",
-            t.name_with_args, max_column ? truncate(t.comment, max_column) : t.comment
-        end
-      when :describe
-        displayable_tasks.each do |t|
-          puts "#{name} #{t.name_with_args}"
-          t.full_comment.split("\n").each do |line|
-            puts "    #{line}"
-          end
-          puts
-        end
-      when :lines
-        displayable_tasks.each do |t|
-          t.locations.each do |loc|
-            printf "#{name} %-30s %s\n",t.name_with_args, loc
-          end
-        end
-      else
-        fail "Unknown show task mode: '#{options.show_tasks}'"
-      end
-    end
-
-    def terminal_width
-      if @terminal_columns.nonzero?
-        result = @terminal_columns
-      else
-        result = unix? ? dynamic_width : 80
-      end
-      (result < 10) ? 80 : result
-    rescue
-      80
-    end
-
-    # Calculate the dynamic width of the
-    def dynamic_width
-      @dynamic_width ||= (dynamic_width_stty.nonzero? || dynamic_width_tput)
-    end
-
-    def dynamic_width_stty
-      %x{stty size 2>/dev/null}.split[1].to_i
-    end
-
-    def dynamic_width_tput
-      %x{tput cols 2>/dev/null}.to_i
-    end
-
-    def unix?
-      RbConfig::CONFIG['host_os'] =~ /(aix|darwin|linux|(net|free|open)bsd|cygwin|solaris|irix|hpux)/i
-    end
-
-    def windows?
-      Win32.windows?
-    end
-
-    def truncate(string, width)
-      if string.length <= width
-        string
-      else
-        ( string[0, width-3] || "" ) + "..."
-      end
-    end
-
-    # Display the tasks and prerequisites
-    def display_prerequisites
-      tasks.each do |t|
-        puts "#{name} #{t.name}"
-        t.prerequisites.each { |pre| puts "    #{pre}" }
-      end
-    end
-
-    # A list of all the standard options used in rake, suitable for
-    # passing to OptionParser.
-    def standard_rake_options
-      [
-        ['--classic-namespace', '-C', "Put Task and FileTask in the top level namespace",
-          lambda { |value|
-            require 'rake/classic_namespace'
-            options.classic_namespace = true
-          }
-        ],
-        ['--describe', '-D [PATTERN]', "Describe the tasks (matching optional PATTERN), then exit.",
-          lambda { |value|
-            options.show_tasks = :describe
-            options.show_task_pattern = Regexp.new(value || '')
-            TaskManager.record_task_metadata = true
-          }
-        ],
-        ['--dry-run', '-n', "Do a dry run without executing actions.",
-          lambda { |value|
-            Rake.verbose(true)
-            Rake.nowrite(true)
-            options.dryrun = true
-            options.trace = true
-          }
-        ],
-        ['--execute',  '-e CODE', "Execute some Ruby code and exit.",
-          lambda { |value|
-            eval(value)
-            exit
-          }
-        ],
-        ['--execute-print',  '-p CODE', "Execute some Ruby code, print the result, then exit.",
-          lambda { |value|
-            puts eval(value)
-            exit
-          }
-        ],
-        ['--execute-continue',  '-E CODE',
-          "Execute some Ruby code, then continue with normal task processing.",
-          lambda { |value| eval(value) }
-        ],
-        ['--libdir', '-I LIBDIR', "Include LIBDIR in the search path for required modules.",
-          lambda { |value| $:.push(value) }
-        ],
-        ['--no-search', '--nosearch', '-N', "Do not search parent directories for the Rakefile.",
-          lambda { |value| options.nosearch = true }
-        ],
-        ['--prereqs', '-P', "Display the tasks and dependencies, then exit.",
-          lambda { |value| options.show_prereqs = true }
-        ],
-        ['--quiet', '-q', "Do not log messages to standard output.",
-          lambda { |value| Rake.verbose(false) }
-        ],
-        ['--rakefile', '-f [FILE]', "Use FILE as the rakefile.",
-          lambda { |value|
-            value ||= ''
-            @rakefiles.clear
-            @rakefiles << value
-          }
-        ],
-        ['--rakelibdir', '--rakelib', '-R RAKELIBDIR',
-          "Auto-import any .rake files in RAKELIBDIR. (default is 'rakelib')",
-          # HACK Use File::PATH_SEPARATOR
-          lambda { |value| options.rakelib = value.split(':') }
-        ],
-        ['--require', '-r MODULE', "Require MODULE before executing rakefile.",
-          lambda { |value|
-            begin
-              require value
-            rescue LoadError => ex
-              begin
-                rake_require value
-              rescue LoadError
-                raise ex
-              end
-            end
-          }
-        ],
-        ['--rules', "Trace the rules resolution.",
-          lambda { |value| options.trace_rules = true }
-        ],
-        ['--silent', '-s', "Like --quiet, but also suppresses the 'in directory' announcement.",
-          lambda { |value|
-            Rake.verbose(false)
-            options.silent = true
-          }
-        ],
-        ['--system',  '-g',
-          "Using system wide (global) rakefiles (usually '~/.rake/*.rake').",
-          lambda { |value| options.load_system = true }
-        ],
-        ['--no-system', '--nosystem', '-G',
-          "Use standard project Rakefile search paths, ignore system wide rakefiles.",
-          lambda { |value| options.ignore_system = true }
-        ],
-        ['--tasks', '-T [PATTERN]', "Display the tasks (matching optional PATTERN) with descriptions, then exit.",
-          lambda { |value|
-            options.show_tasks = :tasks
-            options.show_task_pattern = Regexp.new(value || '')
-            Rake::TaskManager.record_task_metadata = true
-          }
-        ],
-        ['--trace', '-t', "Turn on invoke/execute tracing, enable full backtrace.",
-          lambda { |value|
-            options.trace = true
-            Rake.verbose(true)
-          }
-        ],
-        ['--verbose', '-v', "Log message to standard output.",
-          lambda { |value| Rake.verbose(true) }
-        ],
-        ['--version', '-V', "Display the program version.",
-          lambda { |value|
-            puts "rake, version #{RAKEVERSION}"
-            exit
-          }
-        ],
-        ['--where', '-W [PATTERN]', "Describe the tasks (matching optional PATTERN), then exit.",
-          lambda { |value|
-            options.show_tasks = :lines
-            options.show_task_pattern = Regexp.new(value || '')
-            Rake::TaskManager.record_task_metadata = true
-          }
-        ],
-        ['--no-deprecation-warnings', '-X', "Disable the deprecation warnings.",
-          lambda { |value|
-            options.ignore_deprecate = true
-          }
-        ],
-      ]
-    end
-
-    # Read and handle the command line options.
-    def handle_options
-      options.rakelib = ['rakelib']
-
-      OptionParser.new do |opts|
-        opts.banner = "rake [-f rakefile] {options} targets..."
-        opts.separator ""
-        opts.separator "Options are ..."
-
-        opts.on_tail("-h", "--help", "-H", "Display this help message.") do
-          puts opts
-          exit
-        end
-
-        standard_rake_options.each { |args| opts.on(*args) }
-        opts.environment('RAKEOPT')
-      end.parse!
-
-      # If class namespaces are requested, set the global options
-      # according to the values in the options structure.
-      if options.classic_namespace
-        $show_tasks = options.show_tasks
-        $show_prereqs = options.show_prereqs
-        $trace = options.trace
-        $dryrun = options.dryrun
-        $silent = options.silent
-      end
-    end
-
-    # Similar to the regular Ruby +require+ command, but will check
-    # for *.rake files in addition to *.rb files.
-    def rake_require(file_name, paths=$LOAD_PATH, loaded=$")
-      fn = file_name + ".rake"
-      return false if loaded.include?(fn)
-      paths.each do |path|
-        full_path = File.join(path, fn)
-        if File.exist?(full_path)
-          Rake.load_rakefile(full_path)
-          loaded << fn
-          return true
-        end
-      end
-      fail LoadError, "Can't find #{file_name}"
-    end
-
-    def find_rakefile_location
-      here = Dir.pwd
-      while ! (fn = have_rakefile)
-        Dir.chdir("..")
-        if Dir.pwd == here || options.nosearch
-          return nil
-        end
-        here = Dir.pwd
-      end
-      [fn, here]
-    ensure
-      Dir.chdir(Rake.original_dir)
-    end
-
-    def print_rakefile_directory(location)
-      $stderr.puts "(in #{Dir.pwd})" unless
-        options.silent or original_dir == location
-    end
-
-    def raw_load_rakefile # :nodoc:
-      rakefile, location = find_rakefile_location
-      if (! options.ignore_system) &&
-          (options.load_system || rakefile.nil?) &&
-          system_dir && File.directory?(system_dir)
-        print_rakefile_directory(location)
-        glob("#{system_dir}/*.rake") do |name|
-          add_import name
-        end
-      else
-        fail "No Rakefile found (looking for: #{@rakefiles.join(', ')})" if
-          rakefile.nil?
-        @rakefile = rakefile
-        Dir.chdir(location)
-        print_rakefile_directory(location)
-        $rakefile = @rakefile if options.classic_namespace
-        Rake.load_rakefile(File.expand_path(@rakefile)) if @rakefile && @rakefile != ''
-        options.rakelib.each do |rlib|
-          glob("#{rlib}/*.rake") do |name|
-            add_import name
-          end
-        end
-      end
-      load_imports
-    end
-
-    def glob(path, &block)
-      Dir[path.gsub("\\", '/')].each(&block)
-    end
-    private :glob
-
-    # The directory path containing the system wide rakefiles.
-    def system_dir
-      @system_dir ||=
-        begin
-          if ENV['RAKE_SYSTEM']
-            ENV['RAKE_SYSTEM']
-          else
-            standard_system_dir
-          end
-        end
-    end
-
-    # The standard directory containing system wide rake files.
-    if Win32.windows?
-      def standard_system_dir #:nodoc:
-        Win32.win32_system_dir
-      end
-    else
-      def standard_system_dir #:nodoc:
-        File.join(File.expand_path('~'), '.rake')
-      end
-    end
-    private :standard_system_dir
-
-    # Collect the list of tasks on the command line.  If no tasks are
-    # given, return a list containing only the default task.
-    # Environmental assignments are processed at this time as well.
-    def collect_tasks
-      @top_level_tasks = []
-      ARGV.each do |arg|
-        if arg =~ /^(\w+)=(.*)$/
-          ENV[$1] = $2
-        else
-          @top_level_tasks << arg unless arg =~ /^-/
-        end
-      end
-      @top_level_tasks.push("default") if @top_level_tasks.size == 0
-    end
-
-    # Add a file to the list of files to be imported.
-    def add_import(fn)
-      @pending_imports << fn
-    end
-
-    # Load the pending list of imported files.
-    def load_imports
-      while fn = @pending_imports.shift
-        next if @imported.member?(fn)
-        if fn_task = lookup(fn)
-          fn_task.invoke
-        end
-        ext = File.extname(fn)
-        loader = @loaders[ext] || @default_loader
-        loader.load(fn)
-        @imported << fn
-      end
-    end
-
-    # Warn about deprecated use of top level constant names.
-    def const_warning(const_name)
-      @const_warning ||= false
-      if ! @const_warning
-        $stderr.puts %{WARNING: Deprecated reference to top-level constant '#{const_name}' } +
-          %{found at: #{rakefile_location}} # '
-        $stderr.puts %{    Use --classic-namespace on rake command}
-        $stderr.puts %{    or 'require "rake/classic_namespace"' in Rakefile}
-      end
-      @const_warning = true
-    end
-
-    def rakefile_location backtrace = caller
-      backtrace.map { |t| t[/([^:]+):/,1] }
-
-      re = /^#{@rakefile}$/
-      re = /#{re.source}/i if windows?
-
-      backtrace.find { |str| str =~ re } || ''
-    end
-  end
-end
diff --git a/lib/rake/classic_namespace.rb b/lib/rake/classic_namespace.rb
deleted file mode 100644