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Filename : y2racc
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#!/usr/bin/ruby
#
# $Id$
#
# Copyright (c) 1999-2006 Minero Aoki
#
# This program is free software.
# You can distribute/modify this program under the terms of
# the GNU LGPL, Lesser General Public Lisence version 2.1.
# For details of the GNU LGPL, see the file "COPYING".
#

require 'racc/info'
require 'strscan'
require 'forwardable'
require 'optparse'

def main
  @with_action = true
  @with_header = false
  @with_usercode = false
  cname = 'MyParser'
  input = nil
  output = nil
  parser = OptionParser.new
  parser.banner = "Usage: #{File.basename($0)} [-Ahu] [-c <classname>] [-o <filename>] <input>"
  parser.on('-o', '--output=FILENAME', 'output file name [<input>.racc]') {|name|
    output = name
  }
  parser.on('-c', '--classname=NAME', "Name of the parser class. [#{cname}]") {|name|
    cname = name
  }
  parser.on('-A', '--without-action', 'Does not include actions.') {
    @with_action = false
  }
  parser.on('-h', '--with-header', 'Includes header (%{...%}).') {
    @with_header = true
  }
  parser.on('-u', '--with-user-code', 'Includes user code.') {
    @with_usercode = true
  }
  parser.on('--version', 'Prints version and quit.') {
    puts "y2racc version #{Racc::Version}"
    exit 0
  }
  parser.on('--copyright', 'Prints copyright and quit.') {
    puts Racc::Copyright
    exit 0
  }
  parser.on('--help', 'Prints this message and quit.') {
    puts parser.help
    exit 1
  }
  begin
    parser.parse!
  rescue OptionParser::ParseError => err
    $stderr.puts err.message
    $stderr.puts parser.help
    exit 1
  end
  if ARGV.empty?
    $stderr.puts 'no input'
    exit 1
  end
  if ARGV.size > 1
    $stderr.puts 'too many input'
    exit 1
  end
  input = ARGV[0]

  begin
    result = YaccFileParser.parse_file(input)
    File.open(output || "#{input}.racc", 'w') {|f|
      convert cname, result, f
    }
  rescue SystemCallError => err
    $stderr.puts err.message
    exit 1
  end
end

def convert(classname, result, f)
  init_indent = 'token'.size
  f.puts %<# Converted from "#{result.filename}" by y2racc version #{Racc::Version}>
  f.puts
  f.puts "class #{classname}"
  unless result.terminals.empty?
    f.puts
    f.print 'token'
    columns = init_indent
    result.terminals.each do |t|
      if columns > 60
        f.puts
        f.print ' ' * init_indent
        columns = init_indent
      end
      columns += f.write(" #{t}")
    end
    f.puts
  end
  unless result.precedence_table.empty?
    f.puts
    f.puts 'preclow'
    result.precedence_table.each do |assoc, toks|
      f.printf "  %-8s %s\n", assoc, toks.join(' ')  unless toks.empty?
    end
    f.puts 'prechigh'
  end
  if result.start
    f.puts
    f.puts "start #{@start}"
  end

  f.puts
  f.puts 'rule'
  texts = @with_action ? result.grammar : result.grammar_without_actions
  texts.each do |text|
    f.print text
  end

  if @with_header and result.header
    f.puts
    f.puts '---- header'
    f.puts result.header
  end
  if @with_usercode and result.usercode
    f.puts
    f.puts '---- footer'
    f.puts result.usercode
  end
end

class ParseError < StandardError; end

class StringScanner_withlineno
  def initialize(src)
    @s = StringScanner.new(src)
    @lineno = 1
  end

  extend Forwardable
  def_delegator "@s", :eos?
  def_delegator "@s", :rest

  attr_reader :lineno

  def scan(re)
    advance_lineno(@s.scan(re))
  end

  def scan_until(re)
    advance_lineno(@s.scan_until(re))
  end

  def skip(re)
    str = advance_lineno(@s.scan(re))
    str ? str.size : nil
  end

  def getch
    advance_lineno(@s.getch)
  end

  private

  def advance_lineno(str)
    @lineno += str.count("\n") if str
    str
  end
end

class YaccFileParser

  Result = Struct.new(:terminals, :precedence_table, :start,
                      :header, :grammar, :usercode, :filename)
  class Result   # reopen
    def initialize
      super
      self.terminals = []
      self.precedence_table = []
      self.start = nil
      self.grammar = []
      self.header = nil
      self.usercode = nil
      self.filename = nil
    end

    def grammar_without_actions
      grammar().map {|text| text[0,1] == '{' ? '{}' : text }
    end
  end

  def YaccFileParser.parse_file(filename)
    new().parse(File.read(filename), filename)
  end

  def parse(src, filename = '-')
    @result = Result.new
    @filename = filename
    @result.filename = filename
    s = StringScanner_withlineno.new(src)
    parse_header s
    parse_grammar s
    @result
  end

  private

  COMMENT = %r</\*[^*]*\*+(?:[^/*][^*]*\*+)*/>
  CHAR = /'((?:[^'\\]+|\\.)*)'/
  STRING = /"((?:[^"\\]+|\\.)*)"/

  def parse_header(s)
    skip_until_percent s
    until s.eos?
      case
      when t = s.scan(/left/)
        @result.precedence_table.push ['left', scan_symbols(s)]
      when t = s.scan(/right/)
        @result.precedence_table.push ['right', scan_symbols(s)]
      when t = s.scan(/nonassoc/)
        @result.precedence_table.push ['nonassoc', scan_symbols(s)]
      when t = s.scan(/token/)
        list = scan_symbols(s)
        list.shift if /\A<(.*)>\z/ =~ list[0]
        @result.terminals.concat list
      when t = s.scan(/start/)
        @result.start = scan_symbols(s)[0]
      when s.skip(%r<(?:
            type | union | expect | thong | binary |
            semantic_parser | pure_parser | no_lines |
            raw | token_table
            )\b>x)
        skip_until_percent s
      when s.skip(/\{/)   # header (%{...%})
        str = s.scan_until(/\%\}/)
        str.chop!
        str.chop!
        @result.header = str
        skip_until_percent s
      when s.skip(/\%/)   # grammar (%%...)
        return
      else
        raise ParseError, "#{@filename}:#{s.lineno}: scan error"
      end
    end
  end

  def skip_until_percent(s)
    until s.eos?
      s.skip /[^\%\/]+/
      next if s.skip(COMMENT)
      return if s.getch == '%'
    end
  end

  def scan_symbols(s)
    list = []
    until s.eos?
      s.skip /\s+/
      if s.skip(COMMENT)
        ;
      elsif t = s.scan(CHAR)
        list.push t
      elsif t = s.scan(STRING)
        list.push t
      elsif s.skip(/\%/)
        break
      elsif t = s.scan(/\S+/)
        list.push t
      else
        raise ParseError, "#{@filename}:#{@lineno}: scan error"
      end
    end
    list
  end

  def parse_grammar(s)
    buf = []
    until s.eos?
      if t = s.scan(/[^%'"{\/]+/)
        buf.push t
        break if s.eos?
      end
      if s.skip(/\{/)
        buf.push scan_action(s)
      elsif t = s.scan(/'(?:[^'\\]+|\\.)*'/) then buf.push t
      elsif t = s.scan(/"(?:[^"\\]+|\\.)*"/) then buf.push t
      elsif t = s.scan(COMMENT) then buf.push t
      elsif s.skip(/%prec\b/)   then buf.push '='
      elsif s.skip(/%%/)
        @result.usercode = s.rest
        break
      else
        buf.push s.getch
      end
    end
    @result.grammar = buf
  end

  def scan_action(s)
    buf = '{'
    nest = 1
    until s.eos?
      if t = s.scan(%r<[^/{}'"]+>)
        buf << t
        break if s.eos?
      elsif t = s.scan(COMMENT)
        buf << t
      elsif t = s.scan(CHAR)
        buf << t
      elsif t = s.scan(STRING)
        buf << t
      else
        c = s.getch
        buf << c
        case c
        when '{'
          nest += 1
        when '}'
          nest -= 1
          return buf if nest == 0
        end
      end
    end
    $stderr.puts "warning: unterminated action in #{@filename}"
    buf
  end

end

unless Object.method_defined?(:funcall)
  class Object
    alias funcall __send__
  end
end


main