Re: [boost] [xpressive] Support for multi-capture and balancinggroups

Subject: Re: [boost] [xpressive] Support for multi-capture and balancinggroups
From: Eric Niebler (eric_at_[hidden])
Date: 2010-10-06 21:34:03

On Oct 3, 2:16 am, "Erik Rydgren" <e..._at_[hidden]> wrote:
> > On 10/2/2010 5:52 PM, Erik Rydgren wrote:
> >> Hi!
>
> >> My company have been using pcre for a long while but there has been
> >> gripes about it only returning the last matched value from a capture
> >> group. Because of this I have been searching for a C++ regex engine
> [SNIP]
>
> > This sounds really great and I have every intention of taking this
> > change once I grok it and look over the code. Can you open a feature
> > request ticket athttp://svn.boost.orgso I don't forget, because I'm a
> > little busy at the moment.
>
> Ticket #4704: Support formulticaptureand balancing groups

Hi Erik,

I've been looking at your changes and have some comments. Please see
the bug report: https://svn.boost.org/trac/boost/ticket/4704. In
particular, the last one is a deal-breaker until it's fixed:

"""
Oh wait! I just realized from looking at your change to
mark_end_matcher that you are always populating the captures member of
the sub_match struct (for non-hidden captures). This will have
disastrous performance implications. There cannot potentially be an
allocation every time you match a marked sub-expression. I can't
accept this change.

I suggest you find a way to make this behavior opt-in.
"""

I hope we can find a solution to this problem.

--
Eric Niebler
BoostPro Computing
www.boostpro.com