Replacing libgnuregex

[Joerg Sonnenberger]

On Sun, Apr 16, 2017 at 03:47:56PM +0200, Jilles Tjoelker wrote:
> On Tue, Apr 11, 2017 at 03:20:58PM -0500, Kyle Evans wrote:
> > On the other hand, I think I could fairly easily implement most of these
> > into libc/regex. Here's a summary of what this option entails adding to
> > libc/regex, from what I've found:
> 
> > [snip]
> > * Add backreferences (\1 through \9) to EREs
> > [snip]
> 
> Adding this enforces that EREs, like BREs, may sometimes require
> exponential time to match. I would prefer to avoid that.

The Spencer RE doesn't need backreferences to be exponential, but I
certainly agree that adding support for them makes it more difficult to
change to a better RE implementation later.

Joerg