From: Robert Dober <robert.dober@...>
Date: 2007-04-12T04:47:52+09:00
Subject: Re: Slow ruby regexes

On 4/11/07, Ola Bini <ola.bini@gmail.com> wrote:
> Robert Dober wrote:
> > <snip>
> >
> > stupid me make this simply /a*.*a/ sorry
> Actually, to make it non-backtracking, you just need to update all the
> possible states at the same time. It's quite easy. Just look for
> Thompson NFA for a closer look at it.
> The problem is that it gets problematic with backREFERENCES. That's the
> main problem that is currently solved with backtracking implementations.
>
Thx Ola, I'll look it up.
> What Mentalguy said is basically that there should be better ways of
> implementing regex engines with backreferences. Since you don't use
> backreferences so often, you could have Thompson NFA for those cases
> where it's fast, and switch to a backtracking engine only when you need it.
Yeah I was not concerned with the backreferences, just trying to
understand the basic stuff ;)
>
> Cheers
>
> --
Robert
-- 
You see things; and you say Why?
But I dream things that never were; and I say Why not?
-- George Bernard Shaw