// // traits/start_free.hpp // ~~~~~~~~~~~~~~~~~~~~~ // // Copyright (c) 2003-2020 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 ASIO_TRAITS_START_FREE_HPP #define ASIO_TRAITS_START_FREE_HPP #if defined(_MSC_VER) && (_MSC_VER >= 1200) # pragma once #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) #include "asio/detail/config.hpp" #include "asio/detail/type_traits.hpp" #if defined(ASIO_HAS_DECLTYPE) \ && defined(ASIO_HAS_NOEXCEPT) \ && defined(ASIO_HAS_WORKING_EXPRESSION_SFINAE) # define ASIO_HAS_DEDUCED_START_FREE_TRAIT 1 #endif // defined(ASIO_HAS_DECLTYPE) // && defined(ASIO_HAS_NOEXCEPT) // && defined(ASIO_HAS_WORKING_EXPRESSION_SFINAE) #include "asio/detail/push_options.hpp" namespace asio { namespace traits { template <typename T, typename = void> struct start_free_default; template <typename T, typename = void> struct start_free; } // namespace traits namespace detail { struct no_start_free { ASIO_STATIC_CONSTEXPR(bool, is_valid = false); ASIO_STATIC_CONSTEXPR(bool, is_noexcept = false); }; #if defined(ASIO_HAS_DEDUCED_START_FREE_TRAIT) template <typename T, typename = void> struct start_free_trait : no_start_free { }; template <typename T> struct start_free_trait<T, typename void_type< decltype(start(declval<T>())) >::type> { ASIO_STATIC_CONSTEXPR(bool, is_valid = true); using result_type = decltype(start(declval<T>())); ASIO_STATIC_CONSTEXPR(bool, is_noexcept = noexcept(start(declval<T>()))); }; #else // defined(ASIO_HAS_DEDUCED_START_FREE_TRAIT) template <typename T, typename = void> struct start_free_trait : conditional< is_same<T, typename remove_reference<T>::type>::value, typename conditional< is_same<T, typename add_const<T>::type>::value, no_start_free, traits::start_free<typename add_const<T>::type> >::type, traits::start_free<typename remove_reference<T>::type> >::type { }; #endif // defined(ASIO_HAS_DEDUCED_START_FREE_TRAIT) } // namespace detail namespace traits { template <typename T, typename> struct start_free_default : detail::start_free_trait<T> { }; template <typename T, typename> struct start_free : start_free_default<T> { }; } // namespace traits } // namespace asio #include "asio/detail/pop_options.hpp" #endif // ASIO_TRAITS_START_FREE_HPP