...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::stl_interfaces::v1::v1_dtl::sentinel<Range, void_t< decltype(std::declval< Range & >().end())>>
// In header: <boost/stl_interfaces/fwd.hpp> template<typename Range> struct sentinel<Range, void_t< decltype(std::declval< Range & >().end())>> { // types typedef decltype(std::declval< Range & >().end()) type; };