Re: [boost] [xpressive]: nested regular expressions for dynamic xpressive and basic_regex assignment

From: Eric Niebler (eric_at_[hidden])
Date: 2007-08-27 12:33:25

(Sorry for the delay, I just got back from a week-long vacation.)

Andreas Pokorny wrote:
> Hi Eric,
> I recently tried to make recursive/nested regular expressions available for
> the dynamic regex. It would be cool if you could have look at that.
> http://svn.boost.org/svn/boost/branches/xpressive/nested_dynamic_regex/
> 
> To achieve that I extended the compiler traits, which now includes a
> lookup for references to other regular expressions. I saw that static
> regular expressions used by reference, store a weak pointer to regex
> the regex impl object. For dynamic regular expressions I had to store
> a pointer to the regular expression, and make the class that groups all
> expressions noncopyable.
> 
> Do you see a nicer solution?

Hi Andreas. I *also* recently made nested regexes work for dynamic 
regexes, and I made an announcement about it on this list not too long 
ago. See here: http://lists.boost.org/Archives/boost/2007/06/122641.php. 
In particular, see "Dynamic Regex Grammars with Named Regexes", which 
has the following example:

    sregex_compiler comp;
    sregex rx = comp.compile("^bar(?$RE)baz$");
    comp.compile("(?$RE=)\\d+ \\d+");

The regex_compiler holds a map from names to regex objects. The first 
call to compile() creates a forward reference to a regex object named 
"RE" and the second call binds a regex to the name "RE".

Is this the sort of thing you had in mind? (This is only available in 
the repository -- no public release has this feature yet.)

-- 
Eric Niebler
Boost Consulting
www.boost-consulting.com
The Astoria Seminar ==> http://www.astoriaseminar.com