Re: push parser

[Bob Rossi]

On Mon, Jul 02, 2007 at 10:16:13AM -0400, Joel E. Denny wrote:
> On Mon, 2 Jul 2007, Bob Rossi wrote:
> 
> > OK. I don't even know what push-pull-parser does. When I submitted the
> > patch, I only had support for push-parser and pure-parser didn't effect 
> > it at all. You did some improvements to the patch, and we ended up
> > with push-pull-parser as well. My question is, is push-parser still
> > the same idea as what I committed? If so, what is push-pull-parser?
> >
> > With out knowing what it is, the name seems odd to me. You can have a
> > push parser, and you can have a pull parser, but what's a
> > push-pull-parser? :)
> 
> It's both.
> 
> %push-parser defines yypush_parse.  When combined with %pure-parser, it's 
> close to your original form.
> 
> %push-pull-parser adds yypull_parse, which is a wrapper around 
> yypush_parse that invokes yylex in a loop.  For example, one can 
> yypush_parse tokens to select a subgrammar and then yypull_parse the rest 
> of the input stream.
> 
> %push-pull-parser also defines yyparse, which is a wrapper around 
> yypull_parse.  This yyparse has the same interface as the yyparse 
> generated when neither %push-* directive is specified.
> 
> yypull_parse and yyparse are not defined for %push-parser because that 
> would require the user to define yylex even when he doesn't want to.
> 
> To see some of these interfaces, you might try generating a few example 
> parsers.  It's probably easiest to look at the generated header file.
> 
> Again, the following seems more intuitive to me now:
> 
>   %define push_pull "pull" // default
>   %define push_pull "push"
>   %define push_pull "both"
> 
> > > You can use %pure-parser in combination with either %push-parser or 
> > > %push-pull-parser.

OK, as of today, I'm going to document push-parser, push-pull-parser and
pure-parser in combination with those two. It seemed that perhaps you 
were thinking about reimplementing how this works. Are you?

I just don't want to document this if you think you'll change it
shortly.

Thanks,
Bob Rossi
~