RE: [boost] Re: Announcing: xpressive

From: Brock Peabody (brock.peabody_at_[hidden])
Date: 2003-11-18 16:11:20

> -----Original Message-----
> From: boost-bounces_at_[hidden] [mailto:boost-bounces_at_[hidden]]
> On Behalf Of Eric Niebler

> > In what situations
> would
> > you recommend using static REs over static EBNF via Spirit?
> >
> > Brock
> 
> A) When you want exhaustive backtracking. An RE engine will try every
> possibility to find a match. Spirit does not.

I'd forgotten about backtracking.

> B) When you want you want to mix-n-match statically- and
> dynamically-bound REs in the same expression.  I know Spirit can embed
> Boost.Regex, but ...

That is really cool.

> 
> C) If you need the functionality of both Boost.Regex and Spirit in the
> same application, and you'd like to include and learn only one library.
> 
> D) If you just happen to prefer regular expressions to EBNF.
> 
> Let me emphasize (D). I expect the barrier to entry to xpressive to be
> lower than Spirit for those who are already familiar with regular
> expression syntax (like me!). I expect to provide a little app for
> automatically generating the static xpressions given a perl RE as input.
> This will be a useful learnability tool. And it will be written using
> xpressive, of course. :-)
> 
> I know there is some overlap with existing Boost libraries. I'm going to
> build it because it interests me. Anybody else who is interested can
> help or just stand around and watch. Whether it eventually is accepted
> into Boost as its own library, gets absorbed by Boost.Spirit or is not
> accepted at all is no matter to me. I want it. 'Nuf said.

I do think it sounds very interesting, I was just curious about the regular
expression part, but...

> And with Joel's help, I am going to work to make xpressive and Spirit
> work so well together that the "xpressive or Spirit" question will be
> moot. I hope.

Since it's going to be incorporated with Spirit my questions do seem moot.

Cheers,

Brock