| // |
| // 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 |