...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::xpressive::has_fold_case — Trait used to denote that a traits class has the fold_case member function.
// In header: <boost/xpressive/xpressive_fwd.hpp> template<typename Traits> struct has_fold_case : public is_convertible< Traits::version_tag *, regex_traits_version_1_case_fold_tag * > { };