boost::regex: regex meta data or AST for regex?

cross-posting from boost users - it fits better here:

in concrete:
Is it possible to not only get the #no of groups (sub-expressions) via 
basic_regex::mark_count(), but also their position (begin() / end() 
iterators) in the given regex string (c'tor argument)?

more general:
Can an AST be created for a the given regex string (c'tor argument)?
E.g with boost::spirit?