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Re: switch from byacc to bison

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From:
Dave Mitchell
Date:
February 27, 2004 13:53
Subject:
Re: switch from byacc to bison
Message ID:
20040227215324.GA20460@fdisolutions.com
On Fri, Feb 27, 2004 at 11:39:32AM +0000, Nicholas Clark wrote:
> On Sun, Feb 15, 2004 at 01:17:27AM +0000, Dave Mitchell wrote:
> > On Sat, Feb 14, 2004 at 05:22:46PM +0000, Nicholas Clark wrote:
> > > On Sat, Feb 14, 2004 at 01:46:06PM +0000, Dave Mitchell wrote:
> > > 
> > > > Anyway, I was envisaging that the patch might go into 5.8.x, but it's
> > > > definitely too scary for anything earlier. All the old byacc parser
> > > 
> > > Depends how scarey it looks. How close is its output to the current *.c files,
> > > given the same input?
> > 
> > Well, its like not close at all really. The boilerplate code is totally
> > different, and the tables generally have different names and totally
> > different content. Also, error recovery seems to be better.
> 
> But thinking about merging it, I ask myself "Is it binary compatible?"
> and I don't think I can answer this myself.

Well, I *think* it's binary compatible. It makes a whole bunch of Perl
vars obsolete (like PL_yydebug), but in the main patch (22302) I filled
thinggyvar.h with placeholders, and in a seaprate patch for 5.9.x only
(22303) I removed them altogether. Of course if someone's written
some XS code that directly calls Perl_yylex or uses PL_yydebug, then it
will break, but I can't really see that happening.

So in short, yes, but don't ask me to stake my mother's life on it!

-- 
"The GPL violates the U.S. Constitution, together with copyright,
antitrust and export control laws"
    -- SCO smoking crack again.

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