Run parser gem on a Ractor

parser-ractor.rb

require 'parser/current'

class Parser::Lexer
  methods.grep(/^lex_en/).each do |m|
    if m.end_with?('=')
      singleton_class.undef_method m
    else
      v = __send__ m
      singleton_class.undef_method m
      eval <<~RUBY
        def self.#{m}
          #{v.inspect}
        end
      RUBY
    end
  end

  private_methods.grep(/^_lex_/).each do |m|
    if m.end_with?('=')
      singleton_class.undef_method m
    else
      v = __send__ m
      singleton_class.undef_method m
      eval <<~RUBY
        private_class_method def self.#{m}
          #{v.inspect}
        end
      RUBY
    end
  end

  lex_error = self.lex_error
  singleton_class.undef_method :lex_error
  eval <<~RUBY
    def self.lex_error
      #{lex_error.inspect}
    end
  RUBY

  Ractor.make_shareable(PUNCTUATION)
  Ractor.make_shareable(KEYWORDS)
  Ractor.make_shareable(KEYWORDS_BEGIN)
  Ractor.make_shareable(Literal::TYPES)
  Ractor.make_shareable(Literal::DELIMITERS)
  LEX_STATES.freeze
end

module Parser
  class Ruby31
    # It should be backported to racc
    Ractor.make_shareable(Racc_arg)
    Ractor.make_shareable(Racc_token_to_s_table)
  end
end

# customized builder may solve the problem
class Parser::Builders::Default
  methods.grep(/^emit_/).each do |m|
    if m.end_with?('=')
      singleton_class.undef_method m
    else
      v = __send__ m
      singleton_class.undef_method m
      eval <<~RUBY
        def self.#{m}
          #{v.inspect}
        end
      RUBY
    end
  end
end

rb = File.read(__FILE__)

r = Ractor.new(rb) do |rb|
  Ractor.yield Parser::CurrentRuby.parse(rb)
  Ractor.yield Parser::CurrentRuby.parse("class X;"+rb)
end

p r.take # dispaly AST
p r.take # display parse error