On Tue, 20 Nov 2001, Bill Kelly wrote:

> But this does give me the chance to ask, and now would seem to
> be a good time to do so: Is anyone else out there also working
> on an re engine rewrite?  Wouldn't want to duplicate a lot of
> work(!)
> 
Well, Rockit 0.4 will be built on a parser combinator framework which is
something of a Negexp, ie. you can express regular and non-regular
grammars in it. On the really long-term TODO there is a point mentioning
that this should be used to do a Negexp engine for Ruby but I'm unsure if
its really useful. If you want non-regular stuff (or some hairy regular
stuff) you probably shouldn't compress the description to a short
string. But I'm not sure...

A lot of Rockits Negexp stuff will no doubt be very similar to doing
a Ruby Regexp engine though. Not sure if we can build on each others
stuff. Maybe we can take a look when your stuff matures?

Regards,

Robert

Ps. If you're not familiar with regular vs. non-regular grammars then the
canoncial example of what the former cannot do is balanced/nested
parentheses. You can't do it with one regexp (although people have shown
how to do it with one (two?) regexps and supporting code). In a
"formalism" supporting non-regular grammars it's no problem.