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- //
- // traits/prefer_free.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_PREFER_FREE_HPP
- #define BOOST_ASIO_TRAITS_PREFER_FREE_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_PREFER_FREE_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 Property, typename = void>
- struct prefer_free_default;
- template <typename T, typename Property, typename = void>
- struct prefer_free;
- } // namespace traits
- namespace detail {
- struct no_prefer_free
- {
- BOOST_ASIO_STATIC_CONSTEXPR(bool, is_valid = false);
- BOOST_ASIO_STATIC_CONSTEXPR(bool, is_noexcept = false);
- };
- #if defined(BOOST_ASIO_HAS_DEDUCED_PREFER_FREE_TRAIT)
- template <typename T, typename Property, typename = void>
- struct prefer_free_trait : no_prefer_free
- {
- };
- template <typename T, typename Property>
- struct prefer_free_trait<T, Property,
- typename void_type<
- decltype(prefer(declval<T>(), declval<Property>()))
- >::type>
- {
- BOOST_ASIO_STATIC_CONSTEXPR(bool, is_valid = true);
- using result_type = decltype(
- prefer(declval<T>(), declval<Property>()));
- BOOST_ASIO_STATIC_CONSTEXPR(bool, is_noexcept = noexcept(
- prefer(declval<T>(), declval<Property>())));
- };
- #else // defined(BOOST_ASIO_HAS_DEDUCED_PREFER_FREE_TRAIT)
- template <typename T, typename Property, typename = void>
- struct prefer_free_trait :
- conditional<
- is_same<T, typename decay<T>::type>::value
- && is_same<Property, typename decay<Property>::type>::value,
- no_prefer_free,
- traits::prefer_free<
- typename decay<T>::type,
- typename decay<Property>::type>
- >::type
- {
- };
- #endif // defined(BOOST_ASIO_HAS_DEDUCED_PREFER_FREE_TRAIT)
- } // namespace detail
- namespace traits {
- template <typename T, typename Property, typename>
- struct prefer_free_default :
- detail::prefer_free_trait<T, Property>
- {
- };
- template <typename T, typename Property, typename>
- struct prefer_free :
- prefer_free_default<T, Property>
- {
- };
- } // namespace traits
- } // namespace asio
- } // namespace boost
- #include <boost/asio/detail/pop_options.hpp>
- #endif // BOOST_ASIO_TRAITS_PREFER_FREE_HPP
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