From: Clifford Heath <no@...>
Date: 2008-09-26T09:59:43+09:00
Subject: Re: ANTLR Target for Ruby

Wincent Colaiuta wrote:
> Like Treetop, it is fairly slow, but it works.

Nice!

> But an academic itch that I've wanted to scratch for some time now has
> been turning it into a performance powerhouse; either by replacing the
> dynamically generated parser with a custom Ragel lexer (packaged as a
> C extension for Ruby) or by doing static grammar analysis like ANTLR
> does to identify places where prediction could be used to circumvent
> unnecessary backtracking and jump straight to the right alternative.

What do you think of my third option: Provide memoization only where a
test workload shows the need for it? Backtrack in every situation just
in case, but memoize where testing shows it's useful - totally pragmatic
approach...

> One of the things I always liked about the system was that you wrote
> your grammars in Ruby.

I think that's an error, based on the presumption that "is Ruby, is good".
Not all that's Ruby is golden,,, err... red ;-). By which I mean that
one size doesn't fit all, or we wouldn't need parsers in the first place.

Clifford Heath.