Re: [boost] Re: Regex ease-of-use ideas

From: Pavol Droba (droba_at_[hidden])
Date: 2004-04-07 01:19:35

On Tue, Apr 06, 2004 at 08:33:56PM -0400, David Abrahams wrote:
> "Eric Niebler" <eric_at_[hidden]> writes:
> 
> > David Abrahams wrote:
> >> Pavol Droba <droba_at_[hidden]> writes:
> >>>On Tue, Apr 06, 2004 at 02:43:20PM -0400, David Abrahams wrote:
> >>>>> What would be the advantage? User can write   iterator_range
> >>>>> res=regex_maxch(...);
> >>>>
> >>>>Doesn't the match object get destroyed here, thereby invalidating the
> >>>>iterators?
> >>>>
> >>>Not really as far as I know. Iterators are bound to the collection that is being searched,
> >>>not to the match itself. Therfore, they validity should not be bound the lifetime
> >>>of them match. They will be copied to the iterarator_range.
> >> The match object *is* the collection (of submatches) being searched.
> >> 
> >
> >
> > A sub-match is just a glorified pair of iterators. The iterators refer
> > to the sequence being searched, which has a lifetime independent of
> > the match object. There is no risk of iterator invalidation here.
> 
> I'm not worried about submatch's iterators over the original input
> sequence, but about the match_results's iterators over submatches.
> 

These are destroyed and forgotten. That's the idea of the example.
If you are interested only in the success/failure of the search operation, or
you want to know which part of sequence has been matched, then you don't need
full match_results. Those two iterators (contained in the iterator_range) are
more then sufficient, and you don't need to pay an extra price implied by
match_results.

Maybe I got it wrong, but the discussion before seemed to deal with a problem 
like this.

Pavol