Re: [Emacs-diffs] master 938d252 4/4: Make regex matching reentrant; update syntax during match

[Stefan Monnier <monnier@IRO.UMontreal.CA>]

> Good idea. My reading of the "smart jump" stuff in regex.c suggested that
> we use the optimization for _all_ greedy Kleene star constructs though,
> not just the bounded ones. Am I wrong?

Oh, right, I forgot about that lazy optimization.  We'd need to fix this
so the optimization is performed eagerly.

> But anyway, I think the regex code needs a major overhaul.

Yes, but it's a fairly major project.

> I was actually thinking about forking and vendoring RE2.  Granted,
> having done that, you'd need a C++ compiler to build Emacs, but it's
> probably one of the better actively-maintained DFA-based regex
> engines around.

Yes, it's a nice library, but we'd need to add support for
back-references, which doesn't seem straightforward (I think the
easiest would be to fallback on the old regex engine when backrefs are
present, but keeping two completely different regexp engines is a real
PITA).


        Stefan