Point conceded. Forgot about the parentheses.
"Peter C. Chapin" <[log in to unmask]> writes:
> On Thu, 29 Oct 2009, Gary Johnson wrote:
>> Well, this depends on your language's literal representation of regexes.
>> If they are just a string of white-noise (as per usual), then you can
>> naturally write regexes to match that particular string of white-noise.
> I'm not sure I'd say "naturally." There are plenty of languages that are
> not regular and thus can't be matched by a regular expression. The
> original question becomes: Does the set of regular expressions form a
> regular language? The answer probably depends on just which regular
> expression syntax you are talking about. I believe most practical regular
> expression systems allow arbitrary nesting of matching parenthesis. If so
> that's probably a show stopper. Normally such languages are not regular
> (but are often context free).