Re: Patch for lookaround assertion in regexp

[Nikolai Weibull]

On Mon, Jan 23, 2012 at 15:11, Stefan Monnier <address@hidden> wrote:
>> In 2009, Tomohiro Matsuyama sent a message to this list with a patch
>> to add lookahead/lookbehind assertions to Emacs regular expressions
>> (regexps).  Is there any plan to incorporate this useful feature into
>> an official release?

> I'd like to replace the current regexp engine with one that does not
> suffer from exponential blowup (i.e. using "Thompson's NFA").

> OTOH, noone has submitted code to replace the current regexp engine, and
> I don't forsee I'll have the time to write it myself, so maybe I should
> just give up on this plan.

As an alternative to PCRE, which, as has already been pointed out,
doesn’t match any of these requirements, how about RE2?

http://code.google.com/p/re2/

It’s written in C++, which is a minus, but it should be simple enough
to extend it with \c and \s.