From: Jim Freeze <jim@...>
Date: 2003-12-12T02:26:22+09:00
Subject: Re: problems with racc: $end token

On Friday, 12 December 2003 at  2:16:53 +0900, Luke A. Kanies wrote:
> On Fri, 12 Dec 2003, Jim Freeze wrote:
> 
> > What if you do: return ["", ""]  ?
> 
> I still get a syntax error, but this time the apparently-magical token
> '$end' is not used.
> 
> I know I'm supposed to return false as the token, and that somehow racc
> converts that into the $end token.  I just don't know how it does that,
> nor do I know why racc doesn't then gracefully cease trying to parse,
> rather than continuing on and hitting a syntax error.

Well, in the sample code I see:

    @q.push [false, '$']   # optional from 1.3.7

I have successfully left that out of my parsers.
Essentially, the samples just tokenize the file 
(and store the tokens in @q) then call do_parse.

do_parse apparently gets tokens from the stack by
calling next_token, which returns to tokens one
at a time by calling @q.shift. This would suggest
that when you are done all you need to do is return
the same value as [].shift #=> nil.


-- 
Jim Freeze
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