[Petal] [HELP] Anybody has experience with parsing?

[Jean-Michel Hiver]

> I've got it working with Parse::RecDescent. I suppose now is as good a time as 
> any to expose my unpleasant alternative to Petal. I was working on it before 
> I found Petal, I'm not putting it forward as a competitor or anything. It's 
> not very polished at all but it does seem to be considerably faster due to 
> compiling variable accesses down to Perl rather than parsing them at run 
> time. In fact that's about the only thing it has on Petal.

Your implementation is mostly interesting! I understand the interest of
hinting the code generator on the type of expression that's being
parsed, but on the other hand I really like Petal's ability to 'do the
right thing' given an expression.

I suppose ideally Petal should be able to do both... Also, maybe
something 'like/this' could be turned into something like:

  do {
      my $context = do {
          $context = $Context;
          ($context =~ /=/) ? $context->this() : $context->{this};
      };
      ($context =~ /=/) ? $context->like() : $context->{like};
  };
      
It could be then be brutally dumped in the code that's generated...

Also, I don't think that the 'some_modifier:' syntax should be included
in the Parse::RecDescent grammar because it seriously limits
extensibility. But I would like to see modifiers produce code as well.

For example, 'false: like/this' could become something like:

  not do {
      my $context = do {
          $context = $Context;
          ($context =~ /=/) ? $context->this() : $context->{this};
      };
      ($context =~ /=/) ? $context->like() : $context->{like};
  };

I want to find a way to preserve Petal's feature set, increase its speed
and making the parsing more robust than a bunch of nasty regexes :)

Cheers,
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Jean-Michel Hiver
jhiver at mkdoc.com  - +44 (0)114 255 8097
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