...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::cref — Helper for constructing reference<>
objects that store a reference to const.
// In header: <boost/xpressive/regex_actions.hpp> template<typename T> reference< T const > const cref(T const & t);