boost/asio/traits/prefer_member.hpp
//
// traits/prefer_member.hpp
// ~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2023 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_MEMBER_HPP
#define BOOST_ASIO_TRAITS_PREFER_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_PREFER_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 Property, typename = void>
struct prefer_member_default;
template <typename T, typename Property, typename = void>
struct prefer_member;
} // namespace traits
namespace detail {
struct no_prefer_member
{
BOOST_ASIO_STATIC_CONSTEXPR(bool, is_valid = false);
BOOST_ASIO_STATIC_CONSTEXPR(bool, is_noexcept = false);
};
#if defined(BOOST_ASIO_HAS_DEDUCED_PREFER_MEMBER_TRAIT)
template <typename T, typename Property, typename = void>
struct prefer_member_trait : no_prefer_member
{
};
template <typename T, typename Property>
struct prefer_member_trait<T, Property,
typename void_type<
decltype(declval<T>().prefer(declval<Property>()))
>::type>
{
BOOST_ASIO_STATIC_CONSTEXPR(bool, is_valid = true);
using result_type = decltype(
declval<T>().prefer(declval<Property>()));
BOOST_ASIO_STATIC_CONSTEXPR(bool, is_noexcept = noexcept(
declval<T>().prefer(declval<Property>())));
};
#else // defined(BOOST_ASIO_HAS_DEDUCED_PREFER_MEMBER_TRAIT)
template <typename T, typename Property, typename = void>
struct prefer_member_trait :
conditional<
is_same<T, typename decay<T>::type>::value
&& is_same<Property, typename decay<Property>::type>::value,
no_prefer_member,
traits::prefer_member<
typename decay<T>::type,
typename decay<Property>::type>
>::type
{
};
#endif // defined(BOOST_ASIO_HAS_DEDUCED_PREFER_MEMBER_TRAIT)
} // namespace detail
namespace traits {
template <typename T, typename Property, typename>
struct prefer_member_default :
detail::prefer_member_trait<T, Property>
{
};
template <typename T, typename Property, typename>
struct prefer_member :
prefer_member_default<T, Property>
{
};
} // namespace traits
} // namespace asio
} // namespace boost
#include <boost/asio/detail/pop_options.hpp>
#endif // BOOST_ASIO_TRAITS_PREFER_MEMBER_HPP