// // traits/start_member.hpp // ~~~~~~~~~~~~~~~~~~~~~~~ // // Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com) // // Distributed under the Boost Software License, Version 1.0. (See accompanying // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) // #ifndef BOOST_ASIO_TRAITS_START_MEMBER_HPP #define BOOST_ASIO_TRAITS_START_MEMBER_HPP #if defined(_MSC_VER) && (_MSC_VER >= 1200) # pragma once #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) #include <boost/asio/detail/config.hpp> #include <boost/asio/detail/type_traits.hpp> #if defined(BOOST_ASIO_HAS_DECLTYPE) \ && defined(BOOST_ASIO_HAS_NOEXCEPT) \ && defined(BOOST_ASIO_HAS_WORKING_EXPRESSION_SFINAE) # define BOOST_ASIO_HAS_DEDUCED_START_MEMBER_TRAIT 1 #endif // defined(BOOST_ASIO_HAS_DECLTYPE) // && defined(BOOST_ASIO_HAS_NOEXCEPT) // && defined(BOOST_ASIO_HAS_WORKING_EXPRESSION_SFINAE) #include <boost/asio/detail/push_options.hpp> namespace boost { namespace asio { namespace traits { template <typename T, typename = void> struct start_member_default; template <typename T, typename = void> struct start_member; } // namespace traits namespace detail { struct no_start_member { BOOST_ASIO_STATIC_CONSTEXPR(bool, is_valid = false); BOOST_ASIO_STATIC_CONSTEXPR(bool, is_noexcept = false); }; #if defined(BOOST_ASIO_HAS_DEDUCED_START_MEMBER_TRAIT) template <typename T, typename = void> struct start_member_trait : no_start_member { }; template <typename T> struct start_member_trait<T, typename void_type< decltype(declval<T>().start()) >::type> { BOOST_ASIO_STATIC_CONSTEXPR(bool, is_valid = true); using result_type = decltype(declval<T>().start()); BOOST_ASIO_STATIC_CONSTEXPR(bool, is_noexcept = noexcept(declval<T>().start())); }; #else // defined(BOOST_ASIO_HAS_DEDUCED_START_MEMBER_TRAIT) template <typename T, typename = void> struct start_member_trait : conditional< is_same<T, typename remove_reference<T>::type>::value, typename conditional< is_same<T, typename add_const<T>::type>::value, no_start_member, traits::start_member<typename add_const<T>::type> >::type, traits::start_member<typename remove_reference<T>::type> >::type { }; #endif // defined(BOOST_ASIO_HAS_DEDUCED_START_MEMBER_TRAIT) } // namespace detail namespace traits { template <typename T, typename> struct start_member_default : detail::start_member_trait<T> { }; template <typename T, typename> struct start_member : start_member_default<T> { }; } // namespace traits } // namespace asio } // namespace boost #include <boost/asio/detail/pop_options.hpp> #endif // BOOST_ASIO_TRAITS_START_MEMBER_HPP