Re: Regular expression too big

[Stefan Monnier]

> Thank you for your response.  It was helpful to know that this isn't going
> to be an easy fix.  We're already using regexp-opt, which is supposed to
> optimize and shrink the regex.

In that case I don't think there's much you can do (you may be able to
tweak regexp-opt to reduce the compiled regexp size, but you'll just get
a few percent further, which probably isn't of any use to you).

> I can anticipate the regexes getting much much bigger, and I'm keen to
> avoid having to dig into the guts of the regexp C code, so I think we're
> going to figure out a way to do our regexing outside of Emacs.

Looks like your best/only option.  Of course you may also be able to do it
all in Emacs by not using regexps.  E.g. if your code looks anything like

   (re-search-forward (concat "foo" (regexp-opt mighty-big-list) "bar"))

you may be able to use

   (while (and (re-search-forward (concat "foo\(.*\)bar"))
               (not (member (match-string 1) mighty-big-list))))

And of course, use a hash-table rather than a list.


        Stefan