Hi,
I'm new to lex and yacc and trying to use one of their ruby derivatives to
build a parser for level 2 cascading style-sheets (CSS2). I'm having
trouble deciding whether to use rex & racc or ruby-lex & ruby-yacc. Can
someone help me out by explaining to me the ramifications of choosing
between these two? Does anyone have a particular preference for one over
the other?
Thanks,
Ryan Hanks
p.s. it's my understanding that ruby-* requires flex and yacc, while rex
and racc are pure ruby (please correct me if I'm wrong). That being said,
I'm mostly interested in functionality and ease-of-implementation
differences between the two pairs of packages...
p.p.s. as I said, I'm looking to build a parser for CSS2. might there be an
entirely different parser generator for ruby that I should be looking to use
given the nature of the grammar (
http://www.w3.org/TR/1998/REC-CSS2-19980512/grammar.html\) I'm looking to
parse (such as tdp4r http://rubyforge.org/projects/tdp4r/\)?
Thanks again.
On 11/7/06, Ryan Hanks <ryandhanks@gmail.com> wrote:
Hi,
I'm new to lex and yacc and trying to use one of their ruby derivatives to
build a parser for level 2 cascading style-sheets (CSS2). I'm having
trouble deciding whether to use rex & racc or ruby-lex & ruby-yacc. Can
someone help me out by explaining to me the ramifications of choosing
between these two? Does anyone have a particular preference for one over
the other?Thanks,
Ryan Hanks
I made my decision a long time ago (at least 3+ years), and I don't remember my exact reasoning. However, I do have two racc parsers available for your perusal if you're interested, and one of them is pretty complicated.
I've got a simple Nagios parser in my project named naginator[1], and a pretty complicated one in Puppet[2]. For Puppet, I used StrScan to make a lexer, which has so far worked pretty well; for Nagios, I just wrote a moderately crappy token() method that did the lexing for me.
I know this doesn't help you specifically decide between any of them, but at least it's some code you can look at, which is more than I had when I made my decision (I wrote Naginator about 2 years before I wrote Puppet's parser, and when I went to write Puppet's parser, Naginator's was the only example I could find).
I'd be glad to answer any follow-on questions about them.
I did look at Antlr and Rockit or whatever they're called, but again, I don't remember why I chose against them. I'm sure it was at least partially because I was already pretty familiar with Lex/Yacc-style grammars.
1 - http://reductivelabs.com/cgi-bin/naginator.cgi/browser/trunk/lib/nagios/grammar.ry
2 - http://reductivelabs.com/cgi-bin/puppet.cgi/browser/trunk/lib/puppet/parser/grammar.ra
On Nov 7, 2006, at 4:32 AM, Ryan Hanks wrote:
Hi,
I'm new to lex and yacc and trying to use one of their ruby derivatives to
build a parser for level 2 cascading style-sheets (CSS2). I'm having
trouble deciding whether to use rex & racc or ruby-lex & ruby-yacc. Can
someone help me out by explaining to me the ramifications of choosing
between these two? Does anyone have a particular preference for one over
the other?
--
Luke Kanies
http://madstop.com | http://reductivelabs.com | 615-594-8199
Maybe Antlr and/or ragel could be useful, though I don;t know anything
about them except that:
Ragel is used to create http parser in mongrel, Antlr was mentioned
here sometime ago. Unfortunately I don't remember the topic - try
searching if it interests you.
On 11/7/06, Ryan Hanks <ryandhanks@gmail.com> wrote:
p.s. it's my understanding that ruby-* requires flex and yacc, while rex
and racc are pure ruby (please correct me if I'm wrong). That being said,
I'm mostly interested in functionality and ease-of-implementation
differences between the two pairs of packages...p.p.s. as I said, I'm looking to build a parser for CSS2. might there be an
entirely different parser generator for ruby that I should be looking to use
given the nature of the grammar (
http://www.w3.org/TR/1998/REC-CSS2-19980512/grammar.html\) I'm looking to
parse (such as tdp4r http://rubyforge.org/projects/tdp4r/\)?Thanks again.
On 11/7/06, Ryan Hanks <ryandhanks@gmail.com> wrote:
>
> Hi,
>
> I'm new to lex and yacc and trying to use one of their ruby derivatives to
> build a parser for level 2 cascading style-sheets (CSS2). I'm having
> trouble deciding whether to use rex & racc or ruby-lex & ruby-yacc. Can
> someone help me out by explaining to me the ramifications of choosing
> between these two? Does anyone have a particular preference for one over
> the other?
>
> Thanks,
> Ryan Hanks