Re: [Patch] Support assertions and greedy/ungreedy matching in regex

[Paolo Carlini <paolo dot carlini at oracle dot com>]

Hi,

On 09/12/2013 04:51 PM, Tim Shen wrote:
> On Thu, Sep 12, 2013 at 9:57 AM, Paolo Carlini <paolo.carlini@oracle.com> wrote:
> > Great. A quick-quick comment: if these are the last two features, why we
> > can't un-xfail the testcase which we added latety? Also, a grep revealed a
> > couple more xfails. Can you clarify?
> I say `feature` when I think that, what these xfails reveal are too
> small to be features, say, regex_search/regex_match flags. Now turns
> out "feature" is not a good word for them. I do mean all C++ library
> independent part, or pure regex function part, are done. Next days I
> will add flags implementation.
Ah, Ok, great. Maybe I simply misunderstood: when you added that 
testcase a few days ago, I thought that it simply needed one of the 
missing features. In fact it's about a specific "detail", let's call it 
like that, one of the simple ones part of the work ahead. Fine with me 
of course.
> > Also, much more generally, I would be curious about the remaining work: I
> > think essentially it boils down to the vagaries for the other non-default
> > regex dialects? Is it a lot of work?
> This patch(http://gcc.gnu.org/ml/libstdc++/2013-08/msg00142.html)
> already supports all dialects(ECMAScript, basic, extended, grep,
> egrep, awk) specified by standard. Most of the differences between
> them are eliminated by _Scanner, aka tokenizer, so it's actually not a
> lot of work to even add one more syntax.
Cool. Really, I remember well that patch going in but I thought it was 
only *part* of the work on the other dialects, *not* all of it.
>   But again, I think more
> testcases are needed, especially from those experienced regex users.
> I'm actually not a big fan of regex(but of NFA ;), or can I borrow
> some boost/libc++ testcases without making any licence trouble?
Eh, let me (us) think a bit about that, we don't want to make legal 
mistakes. With boost should be more straightforward, we already borrowed 
shared_ptr for example. First, you could send an email to the author of 
the boost implementation and raise the issue. Of course add me, the 
other v3 maintainers in CC, speak on behalf of the project not just of 
yourself as the actual implementor of our code.

Also, I'm thinking, when those xfails are gone, and the small "details" 
correctly handled, we should have a news entry on the GCC mainpage: will 
be also useful to attract testers.

Paolo.