static_require.hpp
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//
// traits/static_require.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_STATIC_REQUIRE_HPP
#define ASIO_TRAITS_STATIC_REQUIRE_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"
#include "asio/traits/static_query.hpp"
#if defined(ASIO_HAS_DECLTYPE) \
&& defined(ASIO_HAS_NOEXCEPT)
# define ASIO_HAS_DEDUCED_STATIC_REQUIRE_TRAIT 1
#endif // defined(ASIO_HAS_DECLTYPE)
// && defined(ASIO_HAS_NOEXCEPT)
#include "asio/detail/push_options.hpp"
namespace asio {
namespace traits {
template <typename T, typename Property, typename = void>
struct static_require_default;
template <typename T, typename Property, typename = void>
struct static_require;
} // namespace traits
namespace detail {
struct no_static_require
{
ASIO_STATIC_CONSTEXPR(bool, is_valid = false);
};
template <typename T, typename Property, typename = void>
struct static_require_trait :
conditional<
is_same<T, typename decay<T>::type>::value
&& is_same<Property, typename decay<Property>::type>::value,
no_static_require,
traits::static_require<
typename decay<T>::type,
typename decay<Property>::type>
>::type
{
};
#if defined(ASIO_HAS_DEDUCED_STATIC_REQUIRE_TRAIT)
#if defined(ASIO_HAS_WORKING_EXPRESSION_SFINAE)
template <typename T, typename Property>
struct static_require_trait<T, Property,
typename enable_if<
decay<Property>::type::value() == traits::static_query<T, Property>::value()
>::type>
{
ASIO_STATIC_CONSTEXPR(bool, is_valid = true);
};
#else // defined(ASIO_HAS_WORKING_EXPRESSION_SFINAE)
false_type static_require_test(...);
template <typename T, typename Property>
true_type static_require_test(T*, Property*,
typename enable_if<
Property::value() == traits::static_query<T, Property>::value()
>::type* = 0);
template <typename T, typename Property>
struct has_static_require
{
ASIO_STATIC_CONSTEXPR(bool, value =
decltype((static_require_test)(
static_cast<T*>(0), static_cast<Property*>(0)))::value);
};
template <typename T, typename Property>
struct static_require_trait<T, Property,
typename enable_if<
has_static_require<typename decay<T>::type,
typename decay<Property>::type>::value
>::type>
{
ASIO_STATIC_CONSTEXPR(bool, is_valid = true);
};
#endif // defined(ASIO_HAS_WORKING_EXPRESSION_SFINAE)
#endif // defined(ASIO_HAS_DEDUCED_STATIC_REQUIRE_TRAIT)
} // namespace detail
namespace traits {
template <typename T, typename Property, typename>
struct static_require_default : detail::static_require_trait<T, Property>
{
};
template <typename T, typename Property, typename>
struct static_require : static_require_default<T, Property>
{
};
} // namespace traits
} // namespace asio
#include "asio/detail/pop_options.hpp"
#endif // ASIO_TRAITS_STATIC_REQUIRE_HPP