// // Copyright (c) 2020 Alexander Grund // // Distributed under the Boost Software License, Version 1.0. (See // accompanying file LICENSE or copy at // http://www.boost.org/LICENSE_1_0.txt) // #ifndef BOOST_NOWIDE_DETAIL_IS_PATH_HPP_INCLUDED #define BOOST_NOWIDE_DETAIL_IS_PATH_HPP_INCLUDED #include <type_traits> namespace boost { namespace nowide { namespace detail { /// Trait to heuristically check for a *\::filesystem::path /// Done by checking for make_preferred and filename member functions with correct signature template<typename T> struct is_path { template<typename U, U& (U::*)(), U (U::*)() const> struct Check; template<typename U> static std::true_type test(Check<U, &U::make_preferred, &U::filename>*); template<typename U> static std::false_type test(...); static constexpr bool value = decltype(test<T>(0))::value; }; /// SFINAE trait which has a member "type = Result" if the Path is a *\::filesystem::path template<typename Path, typename Result> using enable_if_path_t = typename std::enable_if<is_path<Path>::value, Result>::type; } // namespace detail } // namespace nowide } // namespace boost #endif