Re: Additional Parameter to %merge function in glr-parsers

[Michel Rosien]

Thanks for the reply

> If it's not possible, and you only call 'yyparse()' once,
> then I think you might as well use a globally or statically declared
> pointer to point to the object referenced by your parameter.

This is what I do as a 'quick hack' now but doesn't it kind of defeat the 
purpose of
%pure-parser?
The problem I have now is that I want to call my parser recursively and then 
the global pointer
solution doesn't work

I can solve it I think by maintaining some kind of global stack of pointers 
that I push/pop each time I enter/leave
a recursive call of yyparse(). But to me it seems this is a very big 
work-arround that shouldn't be necessary.

Could it be a good idea to extend yyUserMerge to allow for an extra 
parameter?

Regards,

Michel Rosien

----- Original Message ----- 
From: "Laurence Finston" <address@hidden>
To: "Michel Rosien" <address@hidden>
Cc: <address@hidden>
Sent: Tuesday, June 07, 2005 12:06 PM
Subject: Re: Additional Parameter to %merge function in glr-parsers


> On Mon, 6 Jun 2005, Michel Rosien wrote:
>
> > Is it possible to pass an additional parameter to the %merge function in 
> > glr-parsers?
>
> I don't know, and I didn't find anything in the documentation that
> addresses this question.
>
> > I can pass an additional parameter to the yyparse function with 
> > %parse-param {...}
> > (bison 2.0 documentation, page 63, 107)
> > How can I pass that same argument to the %merge function?
> > (bison 2.0 documentation, page 19)
>
> If it's not possible, and you only call 'yyparse()' once,
> then I think you might as well use a globally or statically declared
> pointer to point to the object referenced by your parameter.  If you
> have multiple calls to 'yyparse()', and it needs to be thread-safe,
> then I suggest using thread-specific data containing a pointer
> to that object (see "man pthread_key_create").  It might also turn
> out to be advantageous to use a pointer to a pointer.
>
> Laurence Finston
> http://www.gnu.org/software/3dldf/LDF.html