Re: 01-ere-layout.patch

[Gary V. Vaughan]

On Thu, Sep 27, 2001 at 11:07:15AM +0200, Akim Demaille wrote:
> 
> This is a proposal to have, some day, ERE support in GNU M4.  I'd
> really love to have it in 1.5...  I still don't know what will be the
> preferred interface.  I'm aiming at patsubst, epatsubst, regexp,
> eregexp.  ?

Looks great.  Feel free to commit (along with some tests and
documentation!).

> Note that I no longer try to free the memory used by Regex, because it
> does it for us.  In particular, now, it can reuse its buffers.  Better
> yet, sometimes it can find out it doesn't have to recompile a pattern
> (ISTR they perform such optimizations.

Really?  Great.  Is this in the regex.c we are using right now?  I am
not sure where the canonical version lives, otherwise I would update
M4's copy and take a look at the docs...  any clues?

> And if they don't, maybe we
> should implement a cache?  Autoconf uses regexp quite a lot, but with
> a small number of RE).

I'm reluctant to put regex caching into M4, it seems like something
that belongs in regex.c.  We need to find a canonical version that we
can submit patches against.  Or at worst, I guess we could have an
m4_regex.c wrapper API that does caching, if it turns out to be
necessary when we find out how the canonical version behaves...

Cheers,
        Gary.
-- 
  ())_. Gary V. Vaughan     gary@(oranda.demon.co.uk|gnu.org)
  ( '/  Research Scientist  http://www.oranda.demon.co.uk       ,_())____
  / )=  GNU Hacker          http://www.gnu.org/software/libtool  \'      `&
`(_~)_  Tech' Author        http://sources.redhat.com/autobook   =`---d__/