From: Benedikt Huber <benedikt@...>
Date: 2012-02-01T09:57:03+09:00
Subject: Re: Which library to write a parser

Ryan Davis wrote in post #1043324:
> On Jan 31, 2012, at 09:30 , Bartosz Dziewoński wrote:
>
>> For heavy lifting, there's always Racc. ruby_parser uses it, and it's
>> pretty fast.
>>
>> http://i.loveruby.net/en/projects/racc/
>> http://rubygems.org/gems/racc
>> http://rubydoc.info/gems/racc/1.4.7/frames
> I did, but with all the complexity of ruby_parser, not the grammar in
> this thread.
Thanks for the numbers. I wrote a small grammar for the MiniP language
in racc, and repeated the experiments (on a different machine, ruby
1.9.3). racc's speed is ok, but it seems to be slower than rsec-ext.

parslet
53.10s
racc
2.05s
rsec-ext
0.72s


> That said, I will say that I only barely tolerate LR based parser
> generators. I would love to have a fully conformant LL-based parser for
> ruby.
I believe both racc and ANTLR won't be faster than rsec-ext, as they
generate ruby code. For many less-convoluted grammars (ruby is not a
good example ;)), a PEG-style parser library is a good and pleasant to
use alternative to a parser generator.

For my prototype, I rewrote a constraint file parser to rsec-ext,
which works great. I can't use it at the moment, because it is 1.9
only, but that's a  different story.

Kind Regards,
Benedikt

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