boost/type_traits/is_detected.hpp

0001 /*
0002 Copyright 2017-2018 Glen Joseph Fernandes
0003 (glenjofe@gmail.com)
0004
0005 Distributed under the Boost Software License,
0006 Version 1.0. (See accompanying file LICENSE_1_0.txt
0007 or copy at http://www.boost.org/LICENSE_1_0.txt)
0008 */
0009
0010 #ifndef BOOST_TT_IS_DETECTED_HPP_INCLUDED
0011 #define BOOST_TT_IS_DETECTED_HPP_INCLUDED
0012
0013 #include <boost/type_traits/detail/detector.hpp>
0014 #include <boost/type_traits/nonesuch.hpp>
0015
0016 namespace boost {
0017
0018 template<template<class...> class Op, class... Args>
0019 using is_detected = typename
0020     detail::detector<nonesuch, void, Op, Args...>::value_t;
0021
0022 #if !defined(BOOST_NO_CXX14_VARIABLE_TEMPLATES)
0023 template<template<class...> class Op, class... Args>
0024 constexpr bool is_detected_v = is_detected<Op, Args...>::value;
0025 #endif
0026
0027 } /* boost */
0028
0029 #endif