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diff --git a/lib/erb.rb b/lib/erb.rb new file mode 100644 index 0000000000..bde90de841 --- /dev/null +++ b/lib/erb.rb @@ -0,0 +1,1179 @@ +# -*- coding: us-ascii -*- +# frozen_string_literal: true +# = ERB -- Ruby Templating +# +# Author:: Masatoshi SEKI +# Documentation:: James Edward Gray II, Gavin Sinclair, and Simon Chiang +# +# See ERB for primary documentation and ERB::Util for a couple of utility +# routines. +# +# Copyright (c) 1999-2000,2002,2003 Masatoshi SEKI +# +# You can redistribute it and/or modify it under the same terms as Ruby. + +# A NOTE ABOUT TERMS: +# +# Formerly: The documentation in this file used the term _template_ to refer to an ERB object. +# +# Now: The documentation in this file uses the term _template_ +# to refer to the string input to ERB.new. +# +# 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. +# +# Therefore we use the term _template_ to refer to: +# +# - The string input to ERB.new +# - The string input to executable erb. +# + +require 'erb/version' +require 'erb/compiler' +require 'erb/def_method' +require 'erb/util' + +# :markup: markdown +# +# Class **ERB** (the name stands for **Embedded Ruby**) +# is an easy-to-use, but also very powerful, [template processor][template processor]. +# +# ## Usage +# +# Before you can use \ERB, you must first require it +# (examples on this page assume that this has been done): +# +# ``` +# require 'erb' +# ``` +# +# ## In Brief +# +# Here's how \ERB works: +# +# - 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: +# +# - [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: +# +# template = 'The magic word is <%= magic_word %>.' +# erb = ERB.new(template) +# magic_word = 'xyzzy' +# erb.result(binding) # => "The magic word is xyzzy." +# +# The above call to #result passes argument `binding`, +# which contains the binding of variable `magic_word` to its string value `'xyzzy'`. +# +# The below call to #result need not pass a binding, +# because its expression `Date::DAYNAMES` is globally defined. +# +# ERB.new('Today is <%= Date::DAYNAMES[Date.today.wday] %>.').result # => "Today is Monday." +# +# - [Execution tags][execution tags]: +# each begins with `'<%'`, ends with `'%>'`; contains Ruby code to be executed: +# +# template = '<% File.write("t.txt", "Some stuff.") %>' +# ERB.new(template).result +# File.read('t.txt') # => "Some stuff." +# +# - [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." +# +# ## Some Simple Examples +# +# Here's a simple example of \ERB in action: +# +# ``` +# template = 'The time is <%= Time.now %>.' +# erb = ERB.new(template) +# erb.result +# # => "The time is 2025-09-09 10:49:26 -0500." +# ``` +# +# Details: +# +# 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. +# +# The +# \ERB object may be re-used: +# +# ``` +# erb.result +# # => "The time is 2025-09-09 10:49:33 -0500." +# ``` +# +# Another example: +# +# ``` +# template = 'The magic word is <%= magic_word %>.' +# erb = ERB.new(template) +# magic_word = 'abracadabra' +# erb.result(binding) +# # => "The magic word is abracadabra." +# ``` +# +# Details: +# +# 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`. +# +# As before, the \ERB object may be re-used: +# +# ``` +# magic_word = 'xyzzy' +# erb.result(binding) +# # => "The magic word is xyzzy." +# ``` +# +# ## Bindings +# +# 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`: +# +# ``` +# 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. +# +# ``` +# template = <<TEMPLATE +# <%# Comment. %> +# TEMPLATE +# erb = ERB.new(template) +# template.encoding # => #<Encoding:UTF-8> +# erb.encoding # => #<Encoding:UTF-8> +# erb.result.encoding # => #<Encoding:UTF-8> +# ``` +# +# You can specify a different encoding by adding a [magic comment][magic comments] +# at the top of the given template: +# +# ``` +# template = <<TEMPLATE +# <%#-*- coding: Big5 -*-%> +# <%# Comment. %> +# TEMPLATE +# erb = ERB.new(template) +# template.encoding # => #<Encoding:UTF-8> +# erb.encoding # => #<Encoding:Big5> +# erb.result.encoding # => #<Encoding:Big5> +# ``` +# +# ## Error Reporting +# +# Consider this template (containing an error): +# +# ``` +# template = '<%= nosuch %>' +# erb = ERB.new(template) +# ``` +# +# 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. +# +# Initially, those values are `nil` and `0`, respectively; +# these initial values are reported as `'(erb)'` and `1`, respectively: +# +# ``` +# erb.filename # => nil +# erb.lineno # => 0 +# erb.result +# (erb):1:in '<main>': undefined local variable or method 'nosuch' for main (NameError) +# ``` +# +# You can use methods #filename= and #lineno= to assign values +# that are more meaningful in your context: +# +# ``` +# erb.filename = 't.txt' +# erb.lineno = 555 +# erb.result +# t.txt:556:in '<main>': undefined local variable or method 'nosuch' for main (NameError) +# ``` +# +# You can use method #location= to set both values: +# +# ``` +# 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 +# +# 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 + # :markup: markdown + # + # :call-seq: + # self.version -> string + # + # Returns the string \ERB version. + def self.version + VERSION + end + + # :markup: markdown + # + # :call-seq: + # ERB.new(template, trim_mode: nil, eoutvar: '_erbout') + # + # Returns a new \ERB object containing the given string +template+. + # + # For details about `template`, its embedded tags, and generated results, see ERB. + # + # **Keyword Argument `trim_mode`** + # + # You can use keyword argument `trim_mode: '%'` + # to enable the [shorthand format][shorthand format] for execution tags. + # + # This value allows [blank line control][blank line control]: + # + # - `'-'`: Omit each blank line ending with `'%>'`. + # + # Other values allow [newline control][newline control]: + # + # - `'>'`: Omit newline for each line ending with `'%>'`. + # - `'<>'`: Omit newline for each line starting with `'<%'` and ending with `'%>'`. + # + # You can also [combine trim modes][combine trim modes]. + # + # **Keyword Argument `eoutvar`** + # + # The string value of keyword argument `eoutvar` specifies the name of the variable + # that method #result uses to construct its result string; + # see #src. + # + # 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. + # + # It's good practice to choose a variable name that begins with an underscore: `'_'`. + # + # [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 + # + 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 + # + # :call-seq: + # make_compiler -> erb_compiler + # + # Returns a new ERB::Compiler with the given `trim_mode`; + # for `trim_mode` values, see ERB.new: + # + # ``` + # 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 + + # :markup: markdown + # + # 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: + # + # ``` + # 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." + # ``` + # + # In a more readable format: + # + # ``` + # # puts erb.src.split('; ') + # # #coding:UTF-8 + # # _erbout = +'' + # # _erbout.<< "The time is ".freeze + # # _erbout.<<(( Time.now ).to_s) + # # _erbout.<< ".".freeze + # # _erbout + # ``` + # + # 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`: + # + # ``` + # 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 + # ``` + # + attr_reader :src + + # :markup: markdown + # + # Returns the encoding of `self`; + # see [Encodings][encodings]: + # + # [encodings]: rdoc-ref:ERB@Encodings + # + attr_reader :encoding + + # :markup: markdown + # + # Sets or returns the file name to be used in reporting errors; + # see [Error Reporting][error reporting]. + # + # [error reporting]: rdoc-ref:ERB@Error+Reporting + attr_accessor :filename + + # :markup: markdown + # + # Sets or returns the line number to be used in reporting errors; + # see [Error Reporting][error reporting]. + # + # [error reporting]: rdoc-ref:ERB@Error+Reporting + attr_accessor :lineno + + # :markup: markdown + # + # :call-seq: + # location = [filename, lineno] => [filename, lineno] + # location = filename -> filename + # + # Sets the values of #filename and, if given, #lineno; + # see [Error Reporting][error reporting]. + # + # [error reporting]: rdoc-ref:ERB@Error+Reporting + def location=((filename, lineno)) + @filename = filename + @lineno = lineno if lineno + end + + # :markup: markdown + # + # :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}.<<" + compiler.insert_cmd = "#{eoutvar}.<<" + compiler.pre_cmd = ["#{eoutvar} = +''"] + compiler.post_cmd = [eoutvar] + end + + # :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 + + # :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 + + # :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 + # + # 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 + + # :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" + # ``` + # + def def_method(mod, methodname, fname='(ERB)') + 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(src, binding, fname, -1) + end + 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 + + # :markup: markdown + # + # :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 + # end + # ``` + # + # Use method #def_class to create a subclass that has method `:render`: + # + # ``` + # MySubClass = template.def_class(MyBaseClass, :render) + # ``` + # + # Generate the result: + # + # ``` + # puts MySubClass.new('foo', 123).render + # <html> + # <body> + # <p>foo</p> + # <p>123</p> + # </body> + # </html> + # ``` + # + def def_class(superklass=Object, methodname='result') + cls = Class.new(superklass) + def_method(cls, methodname, @filename || '(ERB)') + cls + end +end |