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

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? Regards Andreas Pokorny