Hi Thom: On Sat, Oct 25, 2014 at 11:55 AM, Thom Brown <t...@linux.com> wrote:
> Ah, I knew I missed something: > > # SELECT regexp_matches('postgres','(?:g)(r)'); > ...snip, snip... Yes. It's one fo the things I strongly dislike of some of the semantics of postgres ( and others ) regular engine functions. Their return value ''semantics'' depends on data, which makes them difficult to use properly when the pattern argument is unknown. I would prefer to have it always return a list with the full match in the first element, the grouped captures behind it ( i.e., {gr} for '(?:g)r', {gr,g} for '(g)r' . But I think it's dessigned more for interactive use with constant patterns than for programmatic use. .... > > I'm familiar with regular expression syntax, just famliarising myself with > PostgreSQL's syntax flavour. > > Sorry, got confused by the question, and by the fact that I do not know of any regular expression engine with an access function which when presented with non-capturing-group1+unmarked2 returns unmarked2. Even in perl I do not know how to it. Regards. Francisco Olarte.