Re: Patch for lookaround assertion in regexp

[Stefan Monnier <monnier@iro.umontreal.ca>]

>> 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.
> Why not use simply PCRE with a bridge layer which translates from emacs
> regexp format to PCRE? AFAIK the emacs regexes are more or less a subset
> of PCRE, so the translation shouldn't be very difficult.

AFAIK PCRE uses a backtracking implementation, so suffers from the same
exponential blowup as the current code.

> Why reinvent the wheel when PCRE is already there?

I didn't mean to say that I want a fresh new engine written
from scratch.  But adding pcre to the list of libraries linked with
Emacs is not nearly enough: someone has to write the bridge layer and it
may turn out not to be as simple as it seems.


        Stefan