109 lines
2.7 KiB
C++
109 lines
2.7 KiB
C++
|
//
|
||
|
|
// 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 ASIO_TRAITS_PREFER_MEMBER_HPP
|
||
|
|
#define ASIO_TRAITS_PREFER_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_PREFER_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 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
|
||
|
|
{
|
||
|
|
ASIO_STATIC_CONSTEXPR(bool, is_valid = false);
|
||
|
|
ASIO_STATIC_CONSTEXPR(bool, is_noexcept = false);
|
||
|
|
};
|
||
|
|
|
||
|
|
#if defined(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>
|
||
|
|
{
|
||
|
|
ASIO_STATIC_CONSTEXPR(bool, is_valid = true);
|
||
|
|
|
||
|
|
using result_type = decltype(
|
||
|
|
declval<T>().prefer(declval<Property>()));
|
||
|
|
|
||
|
|
ASIO_STATIC_CONSTEXPR(bool, is_noexcept = noexcept(
|
||
|
|
declval<T>().prefer(declval<Property>())));
|
||
|
|
};
|
||
|
|
|
||
|
|
#else // defined(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(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
|
||
|
|
|
||
|
|
#include "asio/detail/pop_options.hpp"
|
||
|
|
|
||
|
|
#endif // ASIO_TRAITS_PREFER_MEMBER_HPP
|