From: Minero Aoki <aamine@...>
Date: 2003-12-12T14:04:01+09:00
Subject: Re: problems with racc: $end token

Hi,

  In mail "Re: problems with racc: $end token"
    "Luke A. Kanies" <luke@madstop.com> wrote:

> There is debugging in racc, and using racc -E to embed the parser and then
> manually setting @yydebug = true can turn it on.  I'm sure there's a
> better way.

Set @yydebug=true in your "inner" and use racc -g.

  % cat t.y
  class MyParser
    options no_result_var
  rule
    program: list
    list   :            { [] }
	   | list ITEM  { val[0].push val[1]; val[0] }

  ---- inner
    def parse
      @tokens = [
	[:ITEM, '1'],
	[:ITEM, '2'],
	[:ITEM, '3']
      ]
      @yydebug = true     #####
      do_parse
    end
    def next_token
      @tokens.shift
    end

  ---- footer
  p MyParser.new.parse

  ~/tmp % racc -ot.rb t.y
  ~/tmp % ruby t.rb
  ["1", "2", "3"]

  ~/tmp % racc -g -ot.rb t.y
  ~/tmp % ruby t.rb
  reduce  <none> --> list
	  [ (list []) ]

  goto    2
	  [ 0 2 ]

  read    :ITEM(ITEM) "1"

  shift   ITEM

      (snip)


> Also, you must set 'return' manually, although it can be any type of
> variable.

Try this:

  class MyParser
    options no_result_var   #### this line
  rule
    ....


Regards,
Minero Aoki