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# -*- 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. require 'cgi/util' require 'erb/version' require 'erb/compiler' require 'erb/def_method' require 'erb/util' # # = ERB -- Ruby Templating # # == Introduction # # ERB provides an easy to use but powerful templating system for Ruby. Using # ERB, actual Ruby code can be added to any plain text document for the # purposes of generating document information details and/or flow control. # # A very simple example is this: # # require 'erb' # # x = 42 # template = ERB.new <<-EOF # The value of x is: <%= x %> # EOF # puts template.result(binding) # # <em>Prints:</em> The value of x is: 42 # # More complex examples are given below. # # # == Recognized Tags # # ERB recognizes certain tags in the provided template and converts them based # on the rules below: # # <% Ruby code -- inline with output %> # <%= Ruby expression -- replace with result %> # <%# comment -- ignored -- useful in testing %> (`<% #` doesn't work. Don't use Ruby comments.) # % a line of Ruby code -- treated as <% line %> (optional -- see ERB.new) # %% replaced with % if first thing on a line and % processing is used # <%% or %%> -- replace with <% or %> respectively # # All other text is passed through ERB filtering unchanged. # # # == Options # # There are several settings you can change when you use ERB: # * the nature of the tags that are recognized; # * the binding used to resolve local variables in the template. # # See the ERB.new and ERB#result methods for more detail. # # == Character encodings # # ERB (or Ruby code generated by ERB) returns a string in the same # character encoding as the input string. When the input string has # a magic comment, however, it returns a string in the encoding specified # by the magic comment. # # # -*- coding: utf-8 -*- # require 'erb' # # template = ERB.new <<EOF # <%#-*- coding: Big5 -*-%> # \_\_ENCODING\_\_ is <%= \_\_ENCODING\_\_ %>. # EOF # puts template.result # # <em>Prints:</em> \_\_ENCODING\_\_ is Big5. # # # == Examples # # === Plain Text # # ERB is useful for any generic templating situation. Note that in this example, we use the # convenient "% at start of line" tag, and we quote the template literally with # <tt>%q{...}</tt> to avoid trouble with the backslash. # # require "erb" # # # Create template. # 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 # }.gsub(/^ /, '') # # message = ERB.new(template, trim_mode: "%<>") # # # Set up template data. # to = "Community Spokesman <spokesman@ruby_community.org>" # priorities = [ "Run Ruby Quiz", # "Document Modules", # "Answer Questions on Ruby Talk" ] # # # Produce result. # email = message.result # puts email # # <i>Generates:</i> # # 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 # # === Ruby in HTML # # ERB is often used in <tt>.rhtml</tt> files (HTML with embedded Ruby). Notice the need in # this example to provide a special binding when the template is run, so that the instance # variables in the Product object can be resolved. # # require "erb" # # # Build template data class. # 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 # # # Create template. # template = %{ # <html> # <head><title>Ruby Toys -- <%= @name %></title></head> # <body> # # <h1><%= @name %> (<%= @code %>)</h1> # <p><%= @desc %></p> # # <ul> # <% @features.each do |f| %> # <li><b><%= f %></b></li> # <% end %> # </ul> # # <p> # <% if @cost < 10 %> # <b>Only <%= @cost %>!!!</b> # <% else %> # Call for a price, today! # <% end %> # </p> # # </body> # </html> # }.gsub(/^ /, '') # # rhtml = ERB.new(template) # # # Set up template data. # toy = Product.new( "TZ-1002", # "Rubysapien", # "Geek's Best Friend! Responds to Ruby commands...", # 999.95 ) # toy.add_feature("Listens for verbal commands in the Ruby language!") # toy.add_feature("Ignores Perl, Java, and all C variants.") # toy.add_feature("Karate-Chop Action!!!") # toy.add_feature("Matz signature on left leg.") # toy.add_feature("Gem studded eyes... Rubies, of course!") # # # Produce result. # rhtml.run(toy.get_binding) # # <i>Generates (some blank lines removed):</i> # # <html> # <head><title>Ruby Toys -- Rubysapien</title></head> # <body> # # <h1>Rubysapien (TZ-1002)</h1> # <p>Geek's Best Friend! Responds to Ruby commands...</p> # # <ul> # <li><b>Listens for verbal commands in the Ruby language!</b></li> # <li><b>Ignores Perl, Java, and all C variants.</b></li> # <li><b>Karate-Chop Action!!!</b></li> # <li><b>Matz signature on left leg.</b></li> # <li><b>Gem studded eyes... Rubies, of course!</b></li> # </ul> # # <p> # Call for a price, today! # </p> # # </body> # </html> # # # == Notes # # There are a variety of templating solutions available in various Ruby projects. # For example, RDoc, distributed with Ruby, uses its own template engine, which # can be reused elsewhere. # # Other popular engines could be found in the corresponding # {Category}[https://www.ruby-toolbox.com/categories/template_engines] of # The Ruby Toolbox. # class ERB Revision = '$Date:: $' # :nodoc: #' deprecate_constant :Revision # Returns revision information for the erb.rb module. def self.version VERSION end # # Constructs a new ERB object with the template specified in _str_. # # An ERB object works by building a chunk of Ruby code that will output # the completed template when run. # # If _trim_mode_ is passed a String containing one or more of the following # modifiers, ERB will adjust its code generation as listed: # # % enables Ruby code processing for lines beginning with % # <> omit newline for lines starting with <% and ending in %> # > omit newline for lines ending in %> # - omit blank lines ending in -%> # # _eoutvar_ can be used to set the name of the variable ERB will build up # its output in. This is useful when you need to run multiple ERB # templates through the same binding and/or when you want to control where # output ends up. Pass the name of the variable to be used inside a String. # # === Example # # require "erb" # # # build data class # class Listings # PRODUCT = { :name => "Chicken Fried Steak", # :desc => "A well messages pattie, breaded and fried.", # :cost => 9.95 } # # attr_reader :product, :price # # def initialize( product = "", price = "" ) # @product = product # @price = price # end # # def build # b = binding # # create and run templates, filling member data variables # ERB.new(<<-'END_PRODUCT'.gsub(/^\s+/, ""), trim_mode: "", eoutvar: "@product").result b # <%= PRODUCT[:name] %> # <%= PRODUCT[:desc] %> # END_PRODUCT # ERB.new(<<-'END_PRICE'.gsub(/^\s+/, ""), trim_mode: "", eoutvar: "@price").result b # <%= PRODUCT[:name] %> -- <%= PRODUCT[:cost] %> # <%= PRODUCT[:desc] %> # END_PRICE # end # end # # # setup template data # listings = Listings.new # listings.build # # puts listings.product + "\n" + listings.price # # _Generates_ # # Chicken Fried Steak # A well messages pattie, breaded and fried. # # Chicken Fried Steak -- 9.95 # A well messages pattie, breaded and fried. # def initialize(str, safe_level=NOT_GIVEN, legacy_trim_mode=NOT_GIVEN, legacy_eoutvar=NOT_GIVEN, trim_mode: nil, eoutvar: '_erbout') # Complex initializer for $SAFE deprecation at [Feature #14256]. Use keyword arguments to pass trim_mode or eoutvar. if safe_level != NOT_GIVEN warn 'Passing safe_level with the 2nd argument of ERB.new is deprecated. Do not use it, and specify other arguments as keyword arguments.', uplevel: 1 end if legacy_trim_mode != NOT_GIVEN warn 'Passing trim_mode with the 3rd argument of ERB.new is deprecated. Use keyword argument like ERB.new(str, trim_mode: ...) instead.', uplevel: 1 trim_mode = legacy_trim_mode end if legacy_eoutvar != NOT_GIVEN warn 'Passing eoutvar with the 4th argument of ERB.new is deprecated. Use keyword argument like ERB.new(str, eoutvar: ...) instead.', uplevel: 1 eoutvar = legacy_eoutvar end compiler = make_compiler(trim_mode) set_eoutvar(compiler, eoutvar) @src, @encoding, @frozen_string = *compiler.compile(str) @filename = nil @lineno = 0 @_init = self.class.singleton_class end NOT_GIVEN = Object.new private_constant :NOT_GIVEN ## # Creates a new compiler for ERB. See ERB::Compiler.new for details def make_compiler(trim_mode) ERB::Compiler.new(trim_mode) end # The Ruby code generated by ERB attr_reader :src # The encoding to eval attr_reader :encoding # The optional _filename_ argument passed to Kernel#eval when the ERB code # is run attr_accessor :filename # The optional _lineno_ argument passed to Kernel#eval when the ERB code # is run attr_accessor :lineno # # Sets optional filename and line number that will be used in ERB code # evaluation and error reporting. See also #filename= and #lineno= # # erb = ERB.new('<%= some_x %>') # erb.render # # undefined local variable or method `some_x' # # from (erb):1 # # erb.location = ['file.erb', 3] # # All subsequent error reporting would use new location # erb.render # # undefined local variable or method `some_x' # # from file.erb:4 # def location=((filename, lineno)) @filename = filename @lineno = lineno if lineno end # # Can be used to set _eoutvar_ as described in ERB::new. It's probably # easier to just use the constructor though, since calling this method # requires the setup of an ERB _compiler_ object. # def set_eoutvar(compiler, eoutvar = '_erbout') compiler.put_cmd = "#{eoutvar}.<<" compiler.insert_cmd = "#{eoutvar}.<<" compiler.pre_cmd = ["#{eoutvar} = +''"] compiler.post_cmd = [eoutvar] end # Generate results and print them. (see ERB#result) def run(b=new_toplevel) print self.result(b) end # # Executes the generated ERB code to produce a completed template, returning # the results of that code. (See ERB::new for details on how this process # can be affected by _safe_level_.) # # _b_ accepts a Binding object which is used to set the context of # code evaluation. # def result(b=new_toplevel) unless @_init.equal?(self.class.singleton_class) raise ArgumentError, "not initialized" end eval(@src, b, (@filename || '(erb)'), @lineno) end # Render a template on a new toplevel binding with local variables specified # by a Hash object. 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 ## # Returns a new binding each time *near* TOPLEVEL_BINDING for runs that do # not specify a binding. def new_toplevel(vars = nil) b = TOPLEVEL_BINDING if vars vars = vars.select {|v| b.local_variable_defined?(v)} unless vars.empty? return b.eval("tap {|;#{vars.join(',')}| break binding}") end end b.dup end private :new_toplevel # Define _methodname_ as instance method of _mod_ from compiled Ruby source. # # example: # filename = 'example.rhtml' # 'arg1' and 'arg2' are used in example.rhtml # erb = ERB.new(File.read(filename)) # erb.def_method(MyClass, 'render(arg1, arg2)', filename) # print MyClass.new.render('foo', 123) def def_method(mod, methodname, fname='(ERB)') src = self.src.sub(/^(?!#|$)/) {"def #{methodname}\n"} << "\nend\n" mod.module_eval do eval(src, binding, fname, -1) end end # Create unnamed module, define _methodname_ as instance method of it, and return it. # # example: # filename = 'example.rhtml' # 'arg1' and 'arg2' are used in example.rhtml # erb = ERB.new(File.read(filename)) # erb.filename = filename # MyModule = erb.def_module('render(arg1, arg2)') # class MyClass # include MyModule # end def def_module(methodname='erb') mod = Module.new def_method(mod, methodname, @filename || '(ERB)') mod end # Define unnamed class which has _methodname_ as instance method, and return it. # # example: # class MyClass_ # def initialize(arg1, arg2) # @arg1 = arg1; @arg2 = arg2 # end # end # filename = 'example.rhtml' # @arg1 and @arg2 are used in example.rhtml # erb = ERB.new(File.read(filename)) # erb.filename = filename # MyClass = erb.def_class(MyClass_, 'render()') # print MyClass.new('foo', 123).render() def def_class(superklass=Object, methodname='result') cls = Class.new(superklass) def_method(cls, methodname, @filename || '(ERB)') cls end end