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- //
- // traits/start_member.hpp
- // ~~~~~~~~~~~~~~~~~~~~~~~
- //
- // Copyright (c) 2003-2022 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_MEMBER_HPP
- #define ASIO_TRAITS_START_MEMBER_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_MEMBER_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_member_default;
- template <typename T, typename = void>
- struct start_member;
- } // namespace traits
- namespace detail {
- struct no_start_member
- {
- ASIO_STATIC_CONSTEXPR(bool, is_valid = false);
- ASIO_STATIC_CONSTEXPR(bool, is_noexcept = false);
- };
- #if defined(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>
- {
- ASIO_STATIC_CONSTEXPR(bool, is_valid = true);
- using result_type = decltype(declval<T>().start());
- ASIO_STATIC_CONSTEXPR(bool,
- is_noexcept = noexcept(declval<T>().start()));
- };
- #else // defined(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(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
- #include "asio/detail/pop_options.hpp"
- #endif // ASIO_TRAITS_START_MEMBER_HPP
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