From: Robert Klemme <bob.news@...>
Date: 2006-02-07T01:43:20+09:00
Subject: Re: Merging regular expressions

Anthony Durity wrote:
> Thanks Robert, thanks Dave,
>
> I see what ye both mean. I was more thinking along the lines of a
> situation like this. To avoid iterating over the array, I would like
> to compress the regexps into a large regexp while still preserving the
> identity of each regexp within the meta-regexp, something akin to what
> happens when the scanner of a lexer is created.
> So, imagine this trivial situation...
>
> r[0] = /a/
> r[1] = /b/
> m = Regexp.union(r0.source, r1.source)
> # _but_ when I go to check s with
> m =~ s
> # if it matches, i want it to tell me which of the original r[i] would
> have matched!

Didn't you originally state that you wanted to ensure that not two regexps
match at the same time?  I mean this is something different.  What you now
state can be done with an alternation - but you'll only see one of your
sub regexps match, i.e. /(foo)|(bar)/.

> See what I mean? Will I hack the Ruby source? Can this be done in
> Ruby? Will I have to do it in C?

The first question is: can this be done with regexps?  First of all I'd
like to hear the exact requirements before we go on with this.  I have the
feeling that they are not clear yet - or at least that they have not
become clear to me.

Cheers

    robert