[ruby-core:22783] Tool to extract non-RIPPER content from parse.y

* parse.y used to be so easy to read ;)

Could this, or something like this, go into <source>/sample/
 where exyacc.rb is distributed?

It's not really a RIPPER tool because it does nothing to help that.

It may look ugly but the FSM I wrote is 3 times the line count. :)

I wouldn't want anyone else to have to waste time writing this.

Use as you wish - no need to ask.


daz


#---------------------------  unRIPPER.rb
#
# Strip #IF/ELSE/ENDIF RIPPER code (as #undef RIPPER)
#  and all RIPPER pre-processing blocks from parse.y
#
# Written in 'perlish' with inspiration from:
#      <RubySource>/sample/exyacc.rb
#
# daz - 2009/03/09 (12:00) - Free of copyright
#

require 'optparse'

### ==========

Ecc  = "\x10"  # Comment End Code (temp)
Hcc  = "\x11"  # Comment Control Code (replaces '#' within C-comment)
IFcc = "\x12"  # #IF(*)  Control Code

IF_RE = 
/^(?!\n)\s*#\s*#{IFcc}(N?DEF)?\s+([^\n]*?)\n^([^#{IFcc}]*?\n)^(?!\n)\s*#\s*END#{IFcc}[^\n]*?\n/mi

# RIPPER pre-processing regex (for '/*%%%*/' and '/*%c%*/' blocks)
#  ( ref: <RubyDir>/ext/ripper/tools/preproc.rb )
RIP_RE = %r{^\s*?/\*%(%|c)%\*/.*?\r?\n(.*?)^\s*/\*%(c?).*?%\*/.*?\r?\n}m
#                [   ( 1 )   ]       ^(_2_)^   [   (3)]   [  ]       

### ==========

def run(input, output)
  y_source = nil
  File.open(input) do |fin|
    y_source = fin.read
  end

  # Make all '*/' a single character to simplify next regex
  y_source.gsub!(%r{\*/}, Ecc)
  #
  # Temporarily substitute '#'-within-comment by Hcc code
  #  to prevent disruption of real #IF blocks.
  y_source.gsub!(%r</\*[^#{Ecc}]*?#{Ecc}>) do |cm|
    cm.gsub!(/(^\s*?)#(\s*IF|ELIF|ELSE|ENDIF)/i, "\\1#{Hcc}\\2")
    cm.chop! << '*/'  # restore '*/' (from Ecc control code)
  end

  # Temporarily replace all 'IF's and END'IF's with a control code
  #  so that nested blocks are correctly grouped.
  y_source.gsub!(/^(\s*)#(\s*)IF(N?DEF)?(\s)/i, "\\1#\\2#{IFcc}\\3\\4")
  y_source.gsub!(/^(\s*)#(\s*END)IF(\s)/i,      "\\1#\\2#{IFcc}\\3")


  # Process #IF/#ELSE/#ENDIF blocks
  rep = true
  rep = y_source.gsub!(IF_RE) do |if_blk|
    m0, df, dfid, ieblk = [$&, ($1 && $1.downcase == 'def'), $2, $3]
    if true and dfid == 'RIPPER'
      iblk, eblk = ieblk.split(/(?!\n)^\s*#\s*ELSE(?>.*?\n)/i)
      (df ? eblk : iblk)  #IF def : ndef RIPPER
    else
      m0.gsub!("#{IFcc}", 'if') # copy entire non-RIPPER IF/ENDIF
    end
  end while rep

  # Restore all '#'-within-comment
  y_source.gsub!("#{Hcc}", '/*?*/')


  ## Remove RIPPER pre-processing directives
  y_source.gsub!(RIP_RE) do
    m0, m1, m2, m3 = [$&, $1, $2, $3]
    if m1 == 'c'
      if m3 != 'c' or m2 !~ /\A\s*\z/
        puts  '~~'*30,  m0,  ' ~'*30
        p [m1, m2, m3], m0
        puts '^^'*30
        raise '? FIXME ?'
      end
      m2 = ''
    end
    m2
  end

  yield y_source if block_given?

  if output
    File.open(output, 'w') do |fout|
      fout.write y_source
    end
  else
    STDOUT.write y_source
  end
end


output = nil
parser = OptionParser.new
parser.banner = "Usage: #{File.basename($0)} [--output=PATH] <parse.y>"
parser.on('--output=PATH', 'The output file - defaults to STDOUT') do |path|
  output = path.gsub("\\", '/')
end
parser.on('--help', 'Prints this message and quits.') do
  puts parser.help
  exit true
end
begin
  parser.parse!
rescue OptionParser::ParseError => err
  STDERR.puts err.message
  STDERR.puts parser.help
  exit false
end
unless ARGV.size == 1
  p ARGV
  abort "Wrong number of arguments (#{ARGV.size} for 1)"
end

input = ARGV[0].gsub("\\", '/')

out_name = output || 'STDOUT'
STDERR.puts 'Input : '  << input
STDERR.puts 'Output: '  << out_name
raise '^ ? Oops ? ^' if output == input

run(input, output) do |y_source|
  # --- Any custom processing, here ---
  STDERR.puts 'Writing output file ' << out_name
  #     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
end
#--------------------------- END