From f3bda8987ecf78aa260e697232876b35f83b67c3 Mon Sep 17 00:00:00 2001
From: Hiroshi SHIBATA <hsbt@ruby-lang.org>
Date: Tue, 16 Nov 2021 20:19:13 +0900
Subject: Merge the master branch of rubygems repo

  Picked from https://github.com/rubygems/rubygems/commit/4b498709a015a94e14a3852a1841a7a3e669133d
---
 lib/rubygems/optparse/lib/optparse.rb | 2230 +++++++++++++++++++++++++++++++++
 1 file changed, 2230 insertions(+)
 create mode 100644 lib/rubygems/optparse/lib/optparse.rb

(limited to 'lib/rubygems/optparse/lib/optparse.rb')

diff --git a/lib/rubygems/optparse/lib/optparse.rb b/lib/rubygems/optparse/lib/optparse.rb
new file mode 100644
index 0000000000..e4b1c61f79
--- /dev/null
+++ b/lib/rubygems/optparse/lib/optparse.rb
@@ -0,0 +1,2230 @@
+# frozen_string_literal: true
+#
+# optparse.rb - command-line option analysis with the Gem::OptionParser class.
+#
+# Author:: Nobu Nakada
+# Documentation:: Nobu Nakada and Gavin Sinclair.
+#
+# See Gem::OptionParser for documentation.
+#
+
+
+#--
+# == Developer Documentation (not for RDoc output)
+#
+# === Class tree
+#
+# - Gem::OptionParser:: front end
+# - Gem::OptionParser::Switch:: each switches
+# - Gem::OptionParser::List:: options list
+# - Gem::OptionParser::ParseError:: errors on parsing
+#   - Gem::OptionParser::AmbiguousOption
+#   - Gem::OptionParser::NeedlessArgument
+#   - Gem::OptionParser::MissingArgument
+#   - Gem::OptionParser::InvalidOption
+#   - Gem::OptionParser::InvalidArgument
+#     - Gem::OptionParser::AmbiguousArgument
+#
+# === Object relationship diagram
+#
+#   +--------------+
+#   | Gem::OptionParser |<>-----+
+#   +--------------+       |                      +--------+
+#                          |                    ,-| Switch |
+#        on_head -------->+---------------+    /  +--------+
+#        accept/reject -->| List          |<|>-
+#                         |               |<|>-  +----------+
+#        on ------------->+---------------+    `-| argument |
+#                           :           :        |  class   |
+#                         +---------------+      |==========|
+#        on_tail -------->|               |      |pattern   |
+#                         +---------------+      |----------|
+#   Gem::OptionParser.accept ->| DefaultList   |      |converter |
+#                reject   |(shared between|      +----------+
+#                         | all instances)|
+#                         +---------------+
+#
+#++
+#
+# == Gem::OptionParser
+#
+# === New to \Gem::OptionParser?
+#
+# See the {Tutorial}[./doc/optparse/tutorial_rdoc.html].
+#
+# === Introduction
+#
+# Gem::OptionParser is a class for command-line option analysis.  It is much more
+# advanced, yet also easier to use, than GetoptLong, and is a more Ruby-oriented
+# solution.
+#
+# === Features
+#
+# 1. The argument specification and the code to handle it are written in the
+#    same place.
+# 2. It can output an option summary; you don't need to maintain this string
+#    separately.
+# 3. Optional and mandatory arguments are specified very gracefully.
+# 4. Arguments can be automatically converted to a specified class.
+# 5. Arguments can be restricted to a certain set.
+#
+# All of these features are demonstrated in the examples below.  See
+# #make_switch for full documentation.
+#
+# === Minimal example
+#
+#   require 'rubygems/optparse/lib/optparse'
+#
+#   options = {}
+#   Gem::OptionParser.new do |parser|
+#     parser.banner = "Usage: example.rb [options]"
+#
+#     parser.on("-v", "--[no-]verbose", "Run verbosely") do |v|
+#       options[:verbose] = v
+#     end
+#   end.parse!
+#
+#   p options
+#   p ARGV
+#
+# === Generating Help
+#
+# Gem::OptionParser can be used to automatically generate help for the commands you
+# write:
+#
+#   require 'rubygems/optparse/lib/optparse'
+#
+#   Options = Struct.new(:name)
+#
+#   class Parser
+#     def self.parse(options)
+#       args = Options.new("world")
+#
+#       opt_parser = Gem::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 'rubygems/optparse/lib/optparse'
+#
+#   options = {}
+#   Gem::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 (Gem::OptionParser::MissingArgument)
+#   $ ruby optparse-test.rb -r my-library
+#   You required my-library!
+#
+# === Type Coercion
+#
+# Gem::OptionParser supports the ability to coerce command line arguments
+# into objects for us.
+#
+# Gem::OptionParser comes with a few ready-to-use kinds of  type
+# coercion. They are:
+#
+# - Date  -- Anything accepted by +Date.parse+
+# - DateTime -- Anything accepted by +DateTime.parse+
+# - Time -- Anything accepted by +Time.httpdate+ or +Time.parse+
+# - URI  -- Anything accepted by +URI.parse+
+# - Shellwords -- Anything accepted by +Shellwords.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.
+# Gem::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 'rubygems/optparse/lib/optparse'
+#   require 'rubygems/optparse/lib/optparse/time'
+#   Gem::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 (Gem::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 Gem::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 'rubygems/optparse/lib/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 = Gem::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 'rubygems/optparse/lib/optparse'
+#
+#   options = {}
+#   Gem::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
+# effect of specifying various options.  This is probably the best way to learn
+# the features of +optparse+.
+#
+#   require 'rubygems/optparse/lib/optparse'
+#   require 'rubygems/optparse/lib/optparse/time'
+#   require 'ostruct'
+#   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" }
+#
+#     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
+#
+#       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.
+#         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.
+#         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.
+#         parser.on("-F", "--irs [OCTAL]", Gem::OptionParser::OctalInteger,
+#                   "Specify record separator (default \\0)") do |rs|
+#           self.record_separator = rs
+#         end
+#       end
+#
+#       def list_example_option(parser)
+#         # List of arguments.
+#         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(', ')
+#         parser.on("--code CODE", CODES, CODE_ALIASES, "Select encoding",
+#                   "(#{code_list})") do |encoding|
+#           self.encoding = encoding
+#         end
+#       end
+#
+#       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.
+#         parser.on("-v", "--[no-]verbose", "Run verbosely") do |v|
+#           self.verbose = v
+#         end
+#       end
+#     end
+#
+#     #
+#     # Return a structure describing the options.
+#     #
+#     def parse(args)
+#       # The options specified on the command line will be collected in
+#       # *options*.
+#
+#       @options = ScriptOptions.new
+#       @args = Gem::OptionParser.new do |parser|
+#         @options.define_options(parser)
+#         parser.parse!(args)
+#       end
+#       @options
+#     end
+#
+#     attr_reader :parser, :options
+#   end  # class OptparseExample
+#
+#   example = OptparseExample.new
+#   options = example.parse(ARGV)
+#   pp options # example.options
+#   pp ARGV
+#
+# === Shell Completion
+#
+# For modern shells (e.g. bash, zsh, etc.), you can use shell
+# completion for command line options.
+#
+# === Further documentation
+#
+# The above examples, along with the accompanying
+# {Tutorial}[./doc/optparse/tutorial_rdoc.html],
+# 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 Gem::OptionParser
+  Gem::OptionParser::Version = "0.2.0"
+
+  # :stopdoc:
+  NoArgument = [NO_ARGUMENT = :NONE, nil].freeze
+  RequiredArgument = [REQUIRED_ARGUMENT = :REQUIRED, true].freeze
+  OptionalArgument = [OPTIONAL_ARGUMENT = :OPTIONAL, false].freeze
+  # :startdoc:
+
+  #
+  # Keyword completion module.  This allows partial arguments to be specified
+  # and resolved against a list of acceptable values.
+  #
+  module Completion
+    def self.regexp(key, icase)
+      Regexp.new('\A' + Regexp.quote(key).gsub(/\w+\b/, '\&\w*'), icase)
+    end
+
+    def self.candidate(key, icase = false, pat = nil, &block)
+      pat ||= Completion.regexp(key, icase)
+      candidates = []
+      block.call do |k, *v|
+        (if Regexp === k
+           kn = ""
+           k === key
+         else
+           kn = defined?(k.id2name) ? k.id2name : k
+           pat === kn
+         end) or next
+        v << k if v.empty?
+        candidates << [k, v, kn]
+      end
+      candidates
+    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
+        canon, sw, * = candidates[0]
+      elsif candidates.size > 1
+        canon, sw, cn = candidates.shift
+        candidates.each do |k, v, kn|
+          next if sw == v
+          if String === cn and String === kn
+            if cn.rindex(kn, 0)
+              canon, sw, cn = k, v, kn
+              next
+            elsif kn.rindex(cn, 0)
+              next
+            end
+          end
+          throw :ambiguous, key
+        end
+      end
+      if canon
+        block_given? or return key, *sw
+        yield(key, *sw)
+      end
+    end
+
+    def convert(opt = nil, val = nil, *)
+      val
+    end
+  end
+
+
+  #
+  # Map from option/keyword string to object with completion.
+  #
+  class OptionMap < Hash
+    include Completion
+  end
+
+
+  #
+  # Individual switch class.  Not important to the user.
+  #
+  # Defined within Switch are several Switch-derived classes: NoArgument,
+  # RequiredArgument, etc.
+  #
+  class Switch
+    attr_reader :pattern, :conv, :short, :long, :arg, :desc, :block
+
+    #
+    # Guesses argument style from +arg+.  Returns corresponding
+    # Gem::OptionParser::Switch class (OptionalArgument, etc.).
+    #
+    def self.guess(arg)
+      case arg
+      when ""
+        t = self
+      when /\A=?\[/
+        t = Switch::OptionalArgument
+      when /\A\s+\[/
+        t = Switch::PlacedArgument
+      else
+        t = Switch::RequiredArgument
+      end
+      self >= t or incompatible_argument_styles(arg, t)
+      t
+    end
+
+    def self.incompatible_argument_styles(arg, t)
+      raise(ArgumentError, "#{arg}: incompatible argument styles\n  #{self}, #{t}",
+            ParseError.filter_backtrace(caller(2)))
+    end
+
+    def self.pattern
+      NilClass
+    end
+
+    def initialize(pattern = nil, conv = nil,
+                   short = nil, long = nil, arg = nil,
+                   desc = ([] if short or long), block = nil, &_block)
+      raise if Array === pattern
+      block ||= _block
+      @pattern, @conv, @short, @long, @arg, @desc, @block =
+        pattern, conv, short, long, arg, desc, block
+    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) # :nodoc:
+      pattern or return nil, [arg]
+      unless m = pattern.match(arg)
+        yield(InvalidArgument, arg)
+        return arg, []
+      end
+      if String === m
+        m = [s = m]
+      else
+        m = m.to_a
+        s = m[0]
+        return nil, m unless String === s
+      end
+      raise InvalidArgument, arg unless arg.rindex(s, 0)
+      return nil, m if s.length == arg.length
+      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 = []) # :nodoc:
+      if conv
+        val = conv.call(*val)
+      else
+        val = proc {|v| v}.call(*val)
+      end
+      return arg, block, val
+    end
+    private :conv_arg
+
+    #
+    # Produces the summary text. Each line of the summary is yielded to the
+    # block (without newline).
+    #
+    # +sdone+::  Already summarized short style options keyed hash.
+    # +ldone+::  Already summarized long style options keyed hash.
+    # +width+::  Width of left side (option part). In other words, the right
+    #            side (description part) starts after +width+ columns.
+    # +max+::    Maximum width of left side -> the options are filled within
+    #            +max+ columns.
+    # +indent+:: Prefix string indents all summarized lines.
+    #
+    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
+      return if sopts.empty? and lopts.empty? # completely hidden
+
+      left = [sopts.join(', ')]
+      right = desc.dup
+
+      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] << (left[-1].empty? ? ' ' * 4 : ', ') << s
+      end
+
+      if arg
+        left[0] << (left[1] ? arg.sub(/\A(\[?)=/, '\1') + ',' : arg)
+      end
+      mlen = left.collect {|ss| ss.length}.max.to_i
+      while mlen > width and l = left.shift
+        mlen = left.collect {|ss| ss.length}.max.to_i if l.length == mlen
+        if l.length < width and (r = right[0]) and !r.empty?
+          l = l.to_s.ljust(width) + ' ' + r
+          right.shift
+        end
+        yield(indent + l)
+      end
+
+      while begin l = left.shift; r = right.shift; l or r end
+        l = l.to_s.ljust(width) + ' ' + r if r and !r.empty?
+        yield(indent + l)
+      end
+
+      self
+    end
+
+    def add_banner(to)  # :nodoc:
+      unless @short or @long
+        s = desc.join
+        to << " [" + s + "]..." unless s.empty?
+      end
+      to
+    end
+
+    def match_nonswitch?(str)  # :nodoc:
+      @pattern =~ str unless @short or @long
+    end
+
+    #
+    # Main name of the switch.
+    #
+    def switch_name
+      (long.first || short.first).sub(/\A-+(?:\[no-\])?/, '')
+    end
+
+    def compsys(sdone, ldone)   # :nodoc:
+      sopts, lopts = [], []
+      @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
+      return if sopts.empty? and lopts.empty? # completely hidden
+
+      (sopts+lopts).each do |opt|
+        # "(-x -c -r)-l[left justify]"
+        if /^--\[no-\](.+)$/ =~ opt
+          o = $1
+          yield("--#{o}", desc.join(""))
+          yield("--no-#{o}", desc.join(""))
+        else
+          yield("#{opt}", desc.join(""))
+        end
+      end
+    end
+
+    #
+    # Switch that takes no arguments.
+    #
+    class NoArgument < self
+
+      #
+      # Raises an exception if any arguments given.
+      #
+      def parse(arg, argv)
+        yield(NeedlessArgument, arg) if arg
+        conv_arg(arg)
+      end
+
+      def self.incompatible_argument_styles(*)
+      end
+
+      def self.pattern
+        Object
+      end
+    end
+
+    #
+    # Switch that takes an argument.
+    #
+    class RequiredArgument < self
+
+      #
+      # Raises an exception if argument is not present.
+      #
+      def parse(arg, argv)
+        unless arg
+          raise MissingArgument if argv.empty?
+          arg = argv.shift
+        end
+        conv_arg(*parse_arg(arg, &method(:raise)))
+      end
+    end
+
+    #
+    # Switch that can omit argument.
+    #
+    class OptionalArgument < self
+
+      #
+      # Parses argument if given, or uses default value.
+      #
+      def parse(arg, argv, &error)
+        if arg
+          conv_arg(*parse_arg(arg, &error))
+        else
+          conv_arg(arg)
+        end
+      end
+    end
+
+    #
+    # Switch that takes an argument, which does not begin with '-'.
+    #
+    class PlacedArgument < self
+
+      #
+      # Returns nil if argument is not present or begins with '-'.
+      #
+      def parse(arg, argv, &error)
+        if !(val = arg) and (argv.empty? or /\A-/ =~ (val = argv[0]))
+          return nil, block, nil
+        end
+        opt = (val = parse_arg(val, &error))[1]
+        val = conv_arg(*val)
+        if opt and !arg
+          argv.shift
+        else
+          val[0] = nil
+        end
+        val
+      end
+    end
+  end
+
+  #
+  # Simple option list providing mapping from short and/or long option
+  # string to Gem::OptionParser::Switch and mapping from acceptable argument to
+  # matching pattern and converter pair. Also provides summary feature.
+  #
+  class List
+    # Map from acceptable argument types to pattern and converter pairs.
+    attr_reader :atype
+
+    # Map from short style option switches to actual switch objects.
+    attr_reader :short
+
+    # Map from long style option switches to actual switch objects.
+    attr_reader :long
+
+    # List of all switches and summary string.
+    attr_reader :list
+
+    #
+    # Just initializes all instance variables.
+    #
+    def initialize
+      @atype = {}
+      @short = OptionMap.new
+      @long = OptionMap.new
+      @list = []
+    end
+
+    #
+    # See Gem::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))
+      else
+        pat = t if t.respond_to?(:match)
+      end
+      unless block
+        block = pat.method(:convert).to_proc if pat.respond_to?(:convert)
+      end
+      @atype[t] = [pat, block]
+    end
+
+    #
+    # See Gem::OptionParser.reject.
+    #
+    def reject(t)
+      @atype.delete(t)
+    end
+
+    #
+    # Adds +sw+ according to +sopts+, +lopts+ and +nlopts+.
+    #
+    # +sw+::     Gem::OptionParser::Switch instance to be added.
+    # +sopts+::  Short style option list.
+    # +lopts+::  Long style option list.
+    # +nlopts+:: Negated long style options list.
+    #
+    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
+    # and negated long options. Arguments are:
+    #
+    # +switch+::      Gem::OptionParser::Switch instance to be inserted.
+    # +short_opts+::  List of short style options.
+    # +long_opts+::   List of long style options.
+    # +nolong_opts+:: List of long style options with "no-" prefix.
+    #
+    #   prepend(switch, short_opts, long_opts, nolong_opts)
+    #
+    def prepend(*args)
+      update(*args)
+      @list.unshift(args[0])
+    end
+
+    #
+    # Appends +switch+ at the tail of the list, and associates short, long
+    # and negated long options. Arguments are:
+    #
+    # +switch+::      Gem::OptionParser::Switch instance to be inserted.
+    # +short_opts+::  List of short style options.
+    # +long_opts+::   List of long style options.
+    # +nolong_opts+:: List of long style options with "no-" prefix.
+    #
+    #   append(switch, short_opts, long_opts, nolong_opts)
+    #
+    def append(*args)
+      update(*args)
+      @list.push(args[0])
+    end
+
+    #
+    # Searches +key+ in +id+ list. The result is returned or yielded if a
+    # block is given. If it isn't found, nil is returned.
+    #
+    def search(id, key)
+      if list = __send__(id)
+        val = list.fetch(key) {return nil}
+        block_given? ? yield(val) : val
+      end
+    end
+
+    #
+    # Searches list +id+ for +opt+ and the optional patterns for completion
+    # +pat+. If +icase+ is true, the search is case insensitive. The result
+    # is returned or yielded if a block is given. If it isn't found, nil is
+    # returned.
+    #
+    def complete(id, opt, icase = false, *pat, &block)
+      __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+.
+    #
+    def each_option(&block)
+      list.each(&block)
+    end
+
+    #
+    # Creates the summary table, passing each line to the +block+ (without
+    # newline). The arguments +args+ are passed along to the summarize
+    # method which is called on every option.
+    #
+    def summarize(*args, &block)
+      sum = []
+      list.reverse_each do |opt|
+        if opt.respond_to?(:summarize) # perhaps Gem::OptionParser::Switch
+          s = []
+          opt.summarize(*args) {|l| s << l}
+          sum.concat(s.reverse)
+        elsif !opt or opt.empty?
+          sum << ""
+        elsif opt.respond_to?(:each_line)
+          sum.concat([*opt.each_line].reverse)
+        else
+          sum.concat([*opt.each].reverse)
+        end
+      end
+      sum.reverse_each(&block)
+    end
+
+    def add_banner(to)  # :nodoc:
+      list.each do |opt|
+        if opt.respond_to?(:add_banner)
+          opt.add_banner(to)
+        end
+      end
+      to
+    end
+
+    def compsys(*args, &block)  # :nodoc:
+      list.each do |opt|
+        if opt.respond_to?(:compsys)
+          opt.compsys(*args, &block)
+        end
+      end
+    end
+  end
+
+  #
+  # Hash with completion search feature. See Gem::OptionParser::Completion.
+  #
+  class CompletingHash < Hash
+    include Completion
+
+    #
+    # Completion for hash key.
+    #
+    def match(key)
+      *values = fetch(key) {
+        raise AmbiguousArgument, catch(:ambiguous) {return complete(key)}
+      }
+      return key, *values
+    end
+  end
+
+  # :stopdoc:
+
+  #
+  # Enumeration of acceptable argument styles. Possible values are:
+  #
+  # NO_ARGUMENT::       The switch takes no arguments. (:NONE)
+  # REQUIRED_ARGUMENT:: The switch requires an argument. (:REQUIRED)
+  # 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 treated as
+  # argument.
+  #
+  ArgumentStyle = {}
+  NoArgument.each {|el| ArgumentStyle[el] = Switch::NoArgument}
+  RequiredArgument.each {|el| ArgumentStyle[el] = Switch::RequiredArgument}
+  OptionalArgument.each {|el| ArgumentStyle[el] = Switch::OptionalArgument}
+  ArgumentStyle.freeze
+
+  #
+  # Switches common used such as '--', and also provides default
+  # argument classes
+  #
+  DefaultList = List.new
+  DefaultList.short['-'] = Switch::NoArgument.new {}
+  DefaultList.long[''] = Switch::NoArgument.new {throw :terminate}
+
+
+  COMPSYS_HEADER = <<'XXX'      # :nodoc:
+
+typeset -A opt_args
+local context state line
+
+_arguments -s -S \
+XXX
+
+  def compsys(to, name = File.basename($0)) # :nodoc:
+    to << "#compdef #{name}\n"
+    to << COMPSYS_HEADER
+    visit(:compsys, {}, {}) {|o, d|
+      to << %Q[  "#{o}[#{d.gsub(/[\"\[\]]/, '\\\\\&')}]" \\\n]
+    }
+    to << "  '*:file:_files' && return 0\n"
+  end
+
+  #
+  # Default options for ARGV, which never appear in option summary.
+  #
+  Officious = {}
+
+  #
+  # --help
+  # Shows option summary.
+  #
+  Officious['help'] = proc do |parser|
+    Switch::NoArgument.new do |arg|
+      puts parser.help
+      exit
+    end
+  end
+
+  #
+  # --*-completion-bash=WORD
+  # Shows candidates for command line completion.
+  #
+  Officious['*-completion-bash'] = proc do |parser|
+    Switch::RequiredArgument.new do |arg|
+      puts parser.candidate(arg)
+      exit
+    end
+  end
+
+  #
+  # --*-completion-zsh[=NAME:FILE]
+  # Creates zsh completion file.
+  #
+  Officious['*-completion-zsh'] = proc do |parser|
+    Switch::OptionalArgument.new do |arg|
+      parser.compsys(STDOUT, arg)
+      exit
+    end
+  end
+
+  #
+  # --version
+  # Shows version string if Version is defined.
+  #
+  Officious['version'] = proc do |parser|
+    Switch::OptionalArgument.new do |pkg|
+      if pkg
+        begin
+          require 'rubygems/optparse/lib/optparse/version'
+        rescue LoadError
+        else
+          show_version(*pkg.split(/,/)) or
+            abort("#{parser.program_name}: no version found in package #{pkg}")
+          exit
+        end
+      end
+      v = parser.ver or abort("#{parser.program_name}: version unknown")
+      puts v
+      exit
+    end
+  end
+
+  # :startdoc:
+
+  #
+  # Class methods
+  #
+
+  #
+  # Initializes a new instance and evaluates the optional block in context
+  # of the instance. Arguments +args+ are passed to #new, see there for
+  # description of parameters.
+  #
+  # This method is *deprecated*, its behavior corresponds to the older #new
+  # method.
+  #
+  def self.with(*args, &block)
+    opts = new(*args)
+    opts.instance_eval(&block)
+    opts
+  end
+
+  #
+  # Returns an incremented value of +default+ according to +arg+.
+  #
+  def self.inc(arg, default = nil)
+    case arg
+    when Integer
+      arg.nonzero?
+    when nil
+      default.to_i + 1
+    end
+  end
+  def inc(*args)
+    self.class.inc(*args)
+  end
+
+  #
+  # Initializes the instance and yields itself if called with a block.
+  #
+  # +banner+:: Banner message.
+  # +width+::  Summary width.
+  # +indent+:: Summary indent.
+  #
+  def initialize(banner = nil, width = 32, indent = ' ' * 4)
+    @stack = [DefaultList, List.new, List.new]
+    @program_name = nil
+    @banner = banner
+    @summary_width = width
+    @summary_indent = indent
+    @default_argv = ARGV
+    @require_exact = false
+    add_officious
+    yield self if block_given?
+  end
+
+  def add_officious  # :nodoc:
+    list = base()
+    Officious.each do |opt, block|
+      list.long[opt] ||= block.call(self)
+    end
+  end
+
+  #
+  # Terminates option parsing. Optional parameter +arg+ is a string pushed
+  # back to be the first non-option argument.
+  #
+  def terminate(arg = nil)
+    self.class.terminate(arg)
+  end
+  def self.terminate(arg = nil)
+    throw :terminate, arg
+  end
+
+  @stack = [DefaultList]
+  def self.top() DefaultList end
+
+  #
+  # Directs to accept specified class +t+. The argument string is passed to
+  # the block in which it should be converted to the desired class.
+  #
+  # +t+::   Argument class specifier, any object including Class.
+  # +pat+:: Pattern for argument, defaults to +t+ if it responds to match.
+  #
+  #   accept(t, pat, &block)
+  #
+  def accept(*args, &blk) top.accept(*args, &blk) end
+  #
+  # See #accept.
+  #
+  def self.accept(*args, &blk) top.accept(*args, &blk) end
+
+  #
+  # Directs to reject specified class argument.
+  #
+  # +t+:: Argument class specifier, any object including Class.
+  #
+  #   reject(t)
+  #
+  def reject(*args, &blk) top.reject(*args, &blk) end
+  #
+  # See #reject.
+  #
+  def self.reject(*args, &blk) top.reject(*args, &blk) end
+
+  #
+  # Instance methods
+  #
+
+  # Heading banner preceding summary.
+  attr_writer :banner
+
+  # Program name to be emitted in error message and default banner,
+  # defaults to $0.
+  attr_writer :program_name
+
+  # Width for option list portion of summary. Must be Numeric.
+  attr_accessor :summary_width
+
+  # Indentation for summary. Must be String (or have + String method).
+  attr_accessor :summary_indent
+
+  # 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
+
+  #
+  # Heading banner preceding summary.
+  #
+  def banner
+    unless @banner
+      @banner = +"Usage: #{program_name} [options]"
+      visit(:add_banner, @banner)
+    end
+    @banner
+  end
+
+  #
+  # Program name to be emitted in error message and default banner, defaults
+  # to $0.
+  #
+  def program_name
+    @program_name || File.basename($0, '.*')
+  end
+
+  # for experimental cascading :-)
+  alias set_banner banner=
+  alias set_program_name program_name=
+  alias set_summary_width summary_width=
+  alias set_summary_indent summary_indent=
+
+  # Version
+  attr_writer :version
+  # Release code
+  attr_writer :release
+
+  #
+  # Version
+  #
+  def version
+    (defined?(@version) && @version) || (defined?(::Version) && ::Version)
+  end
+
+  #
+  # Release code
+  #
+  def release
+    (defined?(@release) && @release) || (defined?(::Release) && ::Release) || (defined?(::RELEASE) && ::RELEASE)
+  end
+
+  #
+  # Returns version string from program_name, version and release.
+  #
+  def ver
+    if v = version
+      str = +"#{program_name} #{[v].join('.')}"
+      str << " (#{v})" if v = release
+      str
+    end
+  end
+
+  def warn(mesg = $!)
+    super("#{program_name}: #{mesg}")
+  end
+
+  def abort(mesg = $!)
+    super("#{program_name}: #{mesg}")
+  end
+
+  #
+  # Subject of #on / #on_head, #accept / #reject
+  #
+  def top
+    @stack[-1]
+  end
+
+  #
+  # Subject of #on_tail.
+  #
+  def base
+    @stack[1]
+  end
+
+  #
+  # Pushes a new List.
+  #
+  def new
+    @stack.push(List.new)
+    if block_given?
+      yield self
+    else
+      self
+    end
+  end
+
+  #
+  # Removes the last List.
+  #
+  def remove
+    @stack.pop
+  end
+
+  #
+  # Puts option summary into +to+ and returns +to+. Yields each line if
+  # a block is given.
+  #
+  # +to+:: Output destination, which must have method <<. Defaults to [].
+  # +width+:: Width of left side, defaults to @summary_width.
+  # +max+:: Maximum length allowed for left side, defaults to +width+ - 1.
+  # +indent+:: Indentation, defaults to @summary_indent.
+  #
+  def summarize(to = [], width = @summary_width, max = width - 1, indent = @summary_indent, &blk)
+    nl = "\n"
+    blk ||= proc {|l| to << (l.index(nl, -1) ? l : l + nl)}
+    visit(:summarize, {}, {}, width, max, indent, &blk)
+    to
+  end
+
+  #
+  # Returns option summary string.
+  #
+  def help; summarize("#{banner}".sub(/\n?\z/, "\n")) end
+  alias to_s help
+
+  #
+  # Returns option summary list.
+  #
+  def to_a; summarize("#{banner}".split(/^/)) end
+
+  #
+  # Checks if an argument is given twice, in which case an ArgumentError is
+  # raised. Called from Gem::OptionParser#switch only.
+  #
+  # +obj+:: New argument.
+  # +prv+:: Previously specified argument.
+  # +msg+:: Exception message.
+  #
+  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} # :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 = [], [], []
+    ldesc, sdesc, desc, arg = [], [], []
+    default_style = Switch::NoArgument
+    default_pattern = nil
+    klass = nil
+    q, a = nil
+    has_arg = false
+
+    opts.each do |o|
+      # argument class
+      next if search(:atype, o) do |pat, c|
+        klass = notwice(o, klass, 'type')
+        if not_style and not_style != Switch::NoArgument
+          not_pattern, not_conv = pat, c
+        else
+          default_pattern, conv = pat, c
+        end
+      end
+
+      # directly specified pattern(any object possible to match)
+      if (!(String === o || Symbol === o)) and o.respond_to?(:match)
+        pattern = notwice(o, pattern, 'pattern')
+        if pattern.respond_to?(:convert)
+          conv = pattern.method(:convert).to_proc
+        else
+          conv = SPLAT_PROC
+        end
+        next
+      end
+
+      # anything others
+      case o
+      when Proc, Method
+        block = notwice(o, block, 'block')
+      when Array, Hash
+        case pattern
+        when CompletingHash
+        when nil
+          pattern = CompletingHash.new
+          conv = pattern.method(:convert).to_proc if pattern.respond_to?(:convert)
+        else
+          raise ArgumentError, "argument pattern given twice"
+        end
+        o.each {|pat, *v| pattern[pat] = v.fetch(0) {pat}}
+      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]*)(.+)?/
+        q, a = $1, $2
+        o = notwice(a ? Object : TrueClass, klass, 'type')
+        not_pattern, not_conv = search(:atype, o) unless not_style
+        not_style = (not_style || default_style).guess(arg = a) if a
+        default_style = Switch::NoArgument
+        default_pattern, conv = search(:atype, FalseClass) unless default_pattern
+        ldesc << "--no-#{q}"
+        (q = q.downcase).tr!('_', '-')
+        long << "no-#{q}"
+        nolong << q
+      when /^--\[no-\]([^\[\]=\s]*)(.+)?/
+        q, a = $1, $2
+        o = notwice(a ? Object : TrueClass, klass, 'type')
+        if a
+          default_style = default_style.guess(arg = a)
+          default_pattern, conv = search(:atype, o) unless default_pattern
+        end
+        ldesc << "--[no-]#{q}"
+        (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]*)(.+)?/
+        q, a = $1, $2
+        if a
+          o = notwice(NilClass, klass, 'type')
+          default_style = default_style.guess(arg = a)
+          default_pattern, conv = search(:atype, o) unless default_pattern
+        end
+        ldesc << "--#{q}"
+        (o = q.downcase).tr!('_', '-')
+        long << o
+      when /^-(\[\^?\]?(?:[^\\\]]|\\.)*\])(.+)?/
+        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 /^-(.)(.+)?/
+        q, a = $1, $2
+        if a
+          o = notwice(NilClass, klass, 'type')
+          default_style = default_style.guess(arg = a)
+          default_pattern, conv = search(:atype, o) unless default_pattern
+        end
+        sdesc << "-#{q}"
+        short << q
+      when /^=/
+        style = notwice(default_style.guess(arg = o), style, 'style')
+        default_pattern, conv = search(:atype, Object) unless default_pattern
+      else
+        desc.push(o)
+      end
+    end
+
+    default_pattern, conv = search(:atype, default_style.pattern) unless default_pattern
+    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)
+    elsif !block
+      if style or pattern
+        raise ArgumentError, "no switch given", ParseError.filter_backtrace(caller)
+      end
+      s = desc
+    else
+      short << pattern
+      s = (style || default_style).new(pattern,
+                                       conv, nil, nil, arg, desc, block)
+    end
+    return s, short, long,
+      (not_style.new(not_pattern, not_conv, sdesc, ldesc, nil, desc, block) if not_style),
+      nolong
+  end
+
+  # :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)
+  #
+  # :include: ../doc/optparse/creates_option.rdoc
+  #
+  def on(*opts, &block)
+    define(*opts, &block)
+    self
+  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)
+  #
+  # :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)
+    self
+  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
+
+  #
+  # :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)
+    self
+  end
+  alias def_tail_option define_tail
+
+  #
+  # Add separator in summary.
+  #
+  def separator(string)
+    top.append(string, nil, nil)
+  end
+
+  #
+  # Parses command line arguments +argv+ in order. When a block is given,
+  # 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, into: nil, &nonopt)
+    argv = argv[0].dup if argv.size == 1 and Array === argv[0]
+    order!(argv, into: into, &nonopt)
+  end
+
+  #
+  # Same as #order, but removes switches destructively.
+  # Non-option arguments remain in +argv+.
+  #
+  def order!(argv = default_argv, into: nil, &nonopt)
+    setter = ->(name, val) {into[name.to_sym] = val} if into
+    parse_in_order(argv, setter, &nonopt)
+  end
+
+  def parse_in_order(argv = default_argv, setter = nil, &nonopt)  # :nodoc:
+    opt, arg, val, rest = nil
+    nonopt ||= proc {|a| throw :terminate, a}
+    argv.unshift(arg) if arg = catch(:terminate) {
+      while arg = argv.shift
+        case arg
+        # long option
+        when /\A--([^=]*)(?:=(.*))?/m
+          opt, rest = $1, $2
+          opt.tr!('_', '-')
+          begin
+            sw, = complete(:long, opt, true)
+            if require_exact && !sw.long.include?(arg)
+              raise InvalidOption, arg
+            end
+          rescue ParseError
+            raise $!.set_option(arg, true)
+          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
+          rescue ParseError
+            raise $!.set_option(arg, rest)
+          end
+
+        # short option
+        when /\A-(.)((=).*|.+)?/m
+          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.delete_prefix('-')
+                has_arg = true
+              rescue InvalidOption
+                raise if require_exact
+                # if no short options match, try completion with long
+                # options.
+                sw, = complete(:long, opt)
+                eq ||= !rest
+              end
+            end
+          rescue ParseError
+            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
+          rescue ParseError
+            raise $!.set_option(arg, arg.length > 2)
+          end
+
+        # non-option argument
+        else
+          catch(:prune) do
+            visit(:each_option) do |sw0|
+              sw = sw0
+              sw.block.call(arg) if Switch === sw and sw.match_nonswitch?(arg)
+            end
+            nonopt.call(arg)
+          end
+        end
+      end
+
+      nil
+    }
+
+    visit(:search, :short, nil) {|sw| sw.block.call(*argv) if !sw.pattern}
+
+    argv
+  end
+  private :parse_in_order
+
+  #
+  # Parses command line arguments +argv+ in permutation mode and returns
+  # 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, into: nil)
+    argv = argv[0].dup if argv.size == 1 and Array === argv[0]
+    permute!(argv, into: into)
+  end
+
+  #
+  # Same as #permute, but removes switches destructively.
+  # Non-option arguments remain in +argv+.
+  #
+  def permute!(argv = default_argv, into: nil)
+    nonopts = []
+    order!(argv, into: into, &nonopts.method(:<<))
+    argv[0, 0] = nonopts
+    argv
+  end
+
+  #
+  # 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, into: nil)
+    argv = argv[0].dup if argv.size == 1 and Array === argv[0]
+    parse!(argv, into: into)
+  end
+
+  #
+  # Same as #parse, but removes switches destructively.
+  # Non-option arguments remain in +argv+.
+  #
+  def parse!(argv = default_argv, into: nil)
+    if ENV.include?('POSIXLY_CORRECT')
+      order!(argv, into: into)
+    else
+      permute!(argv, into: into)
+    end
+  end
+
+  #
+  # Wrapper method for getopts.rb.
+  #
+  #   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
+  #
+  def getopts(*args)
+    argv = Array === args.first ? args.shift : default_argv
+    single_options, *long_options = *args
+
+    result = {}
+
+    single_options.scan(/(.)(:)?/) do |opt, val|
+      if val
+        result[opt] = nil
+        define("-#{opt} VAL")
+      else
+        result[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}=#{result[opt] || "VAL"}", *[desc].compact)
+      else
+        result[opt] = false
+        define("--#{opt}", *[desc].compact)
+      end
+    end
+
+    parse_in_order(argv, result.method(:[]=))
+    result
+  end
+
+  #
+  # See #getopts.
+  #
+  def self.getopts(*args)
+    new.getopts(*args)
+  end
+
+  #
+  # Traverses @stack, sending each element method +id+ with +args+ and
+  # +block+.
+  #
+  def visit(id, *args, &block) # :nodoc:
+    @stack.reverse_each do |el|
+      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) # :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 Gem::OptionParser::Switch.
+  #
+  # +typ+::   Searching table.
+  # +opt+::   Searching key.
+  # +icase+:: Search case insensitive if true.
+  # +pat+::   Optional pattern for completion.
+  #
+  def complete(typ, opt, icase = false, *pat) # :nodoc:
+    if pat.empty?
+      search(typ, opt) {|sw| return [sw, opt]} # exact match or...
+    end
+    ambiguous = catch(:ambiguous) {
+      visit(:complete, typ, opt, icase, *pat) {|o, *sw| return sw}
+    }
+    exc = ambiguous ? AmbiguousOption : InvalidOption
+    raise exc.new(opt, additional: self.method(:additional_message).curry[typ])
+  end
+  private :complete
+
+  #
+  # 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)
+    suggestions = all_candidates & checker.correct(opt)
+    if DidYouMean.respond_to?(:formatter)
+      DidYouMean.formatter.message_for(suggestions)
+    else
+       "\nDid you mean?  #{suggestions.join("\n               ")}"
+    end
+  end
+
+  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
+    end
+    pat = Completion.regexp(word, long)
+    visit(:each_option) do |opt|
+      next unless Switch === opt
+      opts = (long ? opt.long : []) + (short ? opt.short : [])
+      opts = Completion.candidate(word, true, pat, &opts.method(:each)).map(&:first) if pat
+      if /\A=/ =~ opt.arg
+        opts.map! {|sw| sw + "="}
+        if arg and CompletingHash === opt.pattern
+          if opts = opt.pattern.candidate(arg, false, argpat)
+            opts.map!(&:last)
+          end
+        end
+      end
+      list.concat(opts)
+    end
+    list
+  end
+
+  #
+  # Loads options from file names as +filename+. Does nothing when the file
+  # is not present. Returns whether successfully loaded.
+  #
+  # +filename+ defaults to basename of the program without suffix in a
+  # directory ~/.options, then the basename with '.options' suffix
+  # under XDG and Haiku standard places.
+  #
+  def load(filename = nil)
+    unless filename
+      basename = File.basename($0, '.*')
+      return true if load(File.expand_path(basename, '~/.options')) rescue nil
+      basename << ".options"
+      return [
+        # XDG
+        ENV['XDG_CONFIG_HOME'],
+        '~/.config',
+        *ENV['XDG_CONFIG_DIRS']&.split(File::PATH_SEPARATOR),
+
+        # Haiku
+        '~/config/settings',
+      ].any? {|dir|
+        next if !dir or dir.empty?
+        load(File.expand_path(basename, dir)) rescue nil
+      }
+    end
+    begin
+      parse(*IO.readlines(filename).each {|s| s.chomp!})
+      true
+    rescue Errno::ENOENT, Errno::ENOTDIR
+      false
+    end
+  end
+
+  #
+  # Parses environment variable +env+ or its uppercase with splitting like a
+  # shell.
+  #
+  # +env+ defaults to the basename of the program.
+  #
+  def environment(env = File.basename($0, '.*'))
+    env = ENV[env] || ENV[env.upcase] or return
+    require 'shellwords'
+    parse(*Shellwords.shellwords(env))
+  end
+
+  #
+  # Acceptable argument classes
+  #
+
+  #
+  # Any string and no conversion. This is fall-back.
+  #
+  accept(Object) {|s,|s or s.nil?}
+
+  accept(NilClass) {|s,|s}
+
+  #
+  # Any non-empty string, and no conversion.
+  #
+  accept(String, /.+/m) {|s,*|s}
+
+  #
+  # Ruby/C-like integer, octal for 0-7 sequence, binary for 0b, hexadecimal
+  # for 0x, and decimal for others; with optional sign prefix. Converts to
+  # Integer.
+  #
+  decimal = '\d+(?:_\d+)*'
+  binary = 'b[01]+(?:_[01]+)*'
+  hex = 'x[\da-f]+(?:_[\da-f]+)*'
+  octal = "0(?:[0-7]+(?:_[0-7]+)*|#{binary}|#{hex})?"
+  integer = "#{octal}|#{decimal}"
+
+  accept(Integer, %r"\A[-+]?(?:#{integer})\z"io) {|s,|
+    begin
+      Integer(s)
+    rescue ArgumentError
+      raise Gem::OptionParser::InvalidArgument, s
+    end if s
+  }
+
+  #
+  # Float number format, and converts to Float.
+  #
+  float = "(?:#{decimal}(?=(.)?)(?:\\.(?:#{decimal})?)?|\\.#{decimal})(?:E[-+]?#{decimal})?"
+  floatpat = %r"\A[-+]?#{float}\z"io
+  accept(Float, floatpat) {|s,| s.to_f if s}
+
+  #
+  # Generic numeric format, converts to Integer for integer format, Float
+  # for float format, and Rational for rational format.
+  #
+  real = "[-+]?(?:#{octal}|#{float})"
+  accept(Numeric, /\A(#{real})(?:\/(#{real}))?\z/io) {|s, d, f, n,|
+    if n
+      Rational(d, n)
+    elsif f
+      Float(s)
+    else
+      Integer(s)
+    end
+  }
+
+  #
+  # Decimal integer format, to be converted to Integer.
+  #
+  DecimalInteger = /\A[-+]?#{decimal}\z/io
+  accept(DecimalInteger, DecimalInteger) {|s,|
+    begin
+      Integer(s, 10)
+    rescue ArgumentError
+      raise Gem::OptionParser::InvalidArgument, s
+    end if s
+  }
+
+  #
+  # Ruby/C like octal/hexadecimal/binary integer format, to be converted to
+  # Integer.
+  #
+  OctalInteger = /\A[-+]?(?:[0-7]+(?:_[0-7]+)*|0(?:#{binary}|#{hex}))\z/io
+  accept(OctalInteger, OctalInteger) {|s,|
+    begin
+      Integer(s, 8)
+    rescue ArgumentError
+      raise Gem::OptionParser::InvalidArgument, s
+    end if s
+  }
+
+  #
+  # Decimal integer/float number format, to be converted to Integer for
+  # integer format, Float for float format.
+  #
+  DecimalNumeric = floatpat     # decimal integer is allowed as float also.
+  accept(DecimalNumeric, floatpat) {|s, f|
+    begin
+      if f
+        Float(s)
+      else
+        Integer(s)
+      end
+    rescue ArgumentError
+      raise Gem::OptionParser::InvalidArgument, s
+    end if s
+  }
+
+  #
+  # Boolean switch, which means whether it is present or not, whether it is
+  # absent or not with prefix no-, or it takes an argument
+  # yes/no/true/false/+/-.
+  #
+  yesno = CompletingHash.new
+  %w[- no false].each {|el| yesno[el] = false}
+  %w[+ yes true].each {|el| yesno[el] = true}
+  yesno['nil'] = false          # should be nil?
+  accept(TrueClass, yesno) {|arg, val| val == nil or val}
+  #
+  # Similar to TrueClass, but defaults to false.
+  #
+  accept(FalseClass, yesno) {|arg, val| val != nil and val}
+
+  #
+  # List of strings separated by ",".
+  #
+  accept(Array) do |s, |
+    if s
+      s = s.split(',').collect {|ss| ss unless ss.empty?}
+    end
+    s
+  end
+
+  #
+  # Regular expression with options.
+  #
+  accept(Regexp, %r"\A/((?:\\.|[^\\])*)/([[:alpha:]]+)?\z|.*") do |all, s, o|
+    f = 0
+    if o
+      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?
+    end
+    Regexp.new(s || all, f, k)
+  end
+
+  #
+  # Exceptions
+  #
+
+  #
+  # Base class of exceptions from Gem::OptionParser.
+  #
+  class ParseError < RuntimeError
+    # Reason which caused the error.
+    Reason = 'parse error'
+
+    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+.
+    #
+    def recover(argv)
+      argv[0, 0] = @args
+      argv
+    end
+
+    def self.filter_backtrace(array)
+      unless $DEBUG
+        array.delete_if(&%r"\A#{Regexp.quote(__FILE__)}:"o.method(:=~))
+      end
+      array
+    end
+
+    def set_backtrace(array)
+      super(self.class.filter_backtrace(array))
+    end
+
+    def set_option(opt, eq)
+      if eq
+        @args[0] = opt
+      else
+        @args.unshift(opt)
+      end
+      self
+    end
+
+    #
+    # Returns error reason. Override this for I18N.
+    #
+    def reason
+      @reason || self.class::Reason
+    end
+
+    def inspect
+      "#<#{self.class}: #{args.join(' ')}>"
+    end
+
+    #
+    # Default stringizing method to emit standard error message.
+    #
+    def message
+      "#{reason}: #{args.join(' ')}#{additional[@arg0] if additional}"
+    end
+
+    alias to_s message
+  end
+
+  #
+  # Raises when ambiguously completable string is encountered.
+  #
+  class AmbiguousOption < ParseError
+    const_set(:Reason, 'ambiguous option')
+  end
+
+  #
+  # Raises when there is an argument for a switch which takes no argument.
+  #
+  class NeedlessArgument < ParseError
+    const_set(:Reason, 'needless argument')
+  end
+
+  #
+  # Raises when a switch with mandatory argument has no argument.
+  #
+  class MissingArgument < ParseError
+    const_set(:Reason, 'missing argument')
+  end
+
+  #
+  # Raises when switch is undefined.
+  #
+  class InvalidOption < ParseError
+    const_set(:Reason, 'invalid option')
+  end
+
+  #
+  # Raises when the given argument does not match required format.
+  #
+  class InvalidArgument < ParseError
+    const_set(:Reason, 'invalid argument')
+  end
+
+  #
+  # Raises when the given argument word can't be completed uniquely.
+  #
+  class AmbiguousArgument < InvalidArgument
+    const_set(:Reason, 'ambiguous argument')
+  end
+
+  #
+  # Miscellaneous
+  #
+
+  #
+  # Extends command line arguments array (ARGV) to parse itself.
+  #
+  module Arguable
+
+    #
+    # Sets Gem::OptionParser object, when +opt+ is +false+ or +nil+, methods
+    # Gem::OptionParser::Arguable#options and Gem::OptionParser::Arguable#options= are
+    # undefined. Thus, there is no ways to access the Gem::OptionParser object
+    # via the receiver object.
+    #
+    def options=(opt)
+      unless @optparse = opt
+        class << self
+          undef_method(:options)
+          undef_method(:options=)
+        end
+      end
+    end
+
+    #
+    # Actual Gem::OptionParser object, automatically created if nonexistent.
+    #
+    # If called with a block, yields the Gem::OptionParser object and returns the
+    # result of the block. If an Gem::OptionParser::ParseError exception occurs
+    # in the block, it is rescued, a error message printed to STDERR and
+    # +nil+ returned.
+    #
+    def options
+      @optparse ||= Gem::OptionParser.new
+      @optparse.default_argv = self
+      block_given? or return @optparse
+      begin
+        yield @optparse
+      rescue ParseError
+        @optparse.warn $!
+        nil
+      end
+    end
+
+    #
+    # Parses +self+ destructively in order and returns +self+ containing the
+    # rest arguments left unparsed.
+    #
+    def order!(&blk) options.order!(self, &blk) end
+
+    #
+    # Parses +self+ destructively in permutation mode and returns +self+
+    # containing the rest arguments left unparsed.
+    #
+    def permute!() options.permute!(self) end
+
+    #
+    # Parses +self+ destructively and returns +self+ containing the
+    # rest arguments left unparsed.
+    #
+    def parse!() options.parse!(self) end
+
+    #
+    # Substitution of getopts is possible as follows. Also see
+    # Gem::OptionParser#getopts.
+    #
+    #   def getopts(*args)
+    #     ($OPT = ARGV.getopts(*args)).each do |opt, val|
+    #       eval "$OPT_#{opt.gsub(/[^A-Za-z0-9_]/, '_')} = val"
+    #     end
+    #   rescue Gem::OptionParser::ParseError
+    #   end
+    #
+    def getopts(*args)
+      options.getopts(self, *args)
+    end
+
+    #
+    # Initializes instance variable.
+    #
+    def self.extend_object(obj)
+      super
+      obj.instance_eval {@optparse = nil}
+    end
+    def initialize(*args)
+      super
+      @optparse = nil
+    end
+  end
+
+  #
+  # Acceptable argument classes. Now contains DecimalInteger, OctalInteger
+  # and DecimalNumeric. See Acceptable argument classes (in source code).
+  #
+  module Acceptables
+    const_set(:DecimalInteger, Gem::OptionParser::DecimalInteger)
+    const_set(:OctalInteger, Gem::OptionParser::OctalInteger)
+    const_set(:DecimalNumeric, Gem::OptionParser::DecimalNumeric)
+  end
+end
+
+# ARGV is arguable by Gem::OptionParser
+ARGV.extend(Gem::OptionParser::Arguable)
-- 
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