Re: regex.c: emacs & glibc (and xemacs, and grep and ...)

[Paul Eggert <eggert@twinsun.com>]

> From: "Stefan Monnier" <monnier+gnu/emacs@RUM.cs.yale.edu>
> Date: Thu, 04 Apr 2002 14:24:55 -0500
> 
> In the mean time, supposedly glibc has switched to a new code base for its
> regexp engine (I know glibc maintainers hated the regexp code, and I can
> partly understand why, although the Emacs version has been somewhat
> improved) which seems inadequate (for now at least) for Emacs and even
> somewhat unstable, last I heard of it.

My impression is that the new glibc engine still needs some work.
I've been communicating with Isamu Hasegawa, its author, and have
mostly focused on RE compatibility concerns, notably POSIX
conformance.  His first goal, understandably so, is to get it up to
speed for glibc's own purposes, and later to worry about other uses
like grep and Emacs.

In other news, the 2001 edition of the original Unix regular
expression code has been distributed under the LGPL by Caldera, the
current copyright holders.  This was done after the IBM contribution.
However, I haven't had a chance to look at the Unix code.  If you're
interested, it's in <http://unixtools.sourceforge.net/>.


> I don't know what GNU grep uses,

Grep uses a version of regex.c that forked from the glibc version
after Emacs did.  The GNU core utilities have a version that forked
from glibc after Emacs did, but before grep did.  I don't know about
the gnulib version (perhaps it's supposed to be identical to the Emacs
version?).

It is a bit of a mess.  With the exception of the new glibc code and
the Unix code, it should be relatively easy to merge all these
versions, if someone could find the time.