1//===----------------------------------------------------------------------===// 2// 3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4// See https://llvm.org/LICENSE.txt for license information. 5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6// 7//===----------------------------------------------------------------------===// 8 9#ifndef _LIBCPP___COMPARE_COMPARE_THREE_WAY_RESULT_H 10#define _LIBCPP___COMPARE_COMPARE_THREE_WAY_RESULT_H 11 12#include <__config> 13#include <__type_traits/make_const_lvalue_ref.h> 14#include <__utility/declval.h> 15 16#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 17# pragma GCC system_header 18#endif 19 20_LIBCPP_BEGIN_NAMESPACE_STD 21 22#if _LIBCPP_STD_VER > 17 23 24template<class, class, class> 25struct _LIBCPP_HIDE_FROM_ABI __compare_three_way_result { }; 26 27template<class _Tp, class _Up> 28struct _LIBCPP_HIDE_FROM_ABI __compare_three_way_result<_Tp, _Up, decltype( 29 std::declval<__make_const_lvalue_ref<_Tp>>() <=> std::declval<__make_const_lvalue_ref<_Up>>(), void() 30)> { 31 using type = decltype(std::declval<__make_const_lvalue_ref<_Tp>>() <=> std::declval<__make_const_lvalue_ref<_Up>>()); 32}; 33 34template<class _Tp, class _Up = _Tp> 35struct _LIBCPP_TEMPLATE_VIS compare_three_way_result : __compare_three_way_result<_Tp, _Up, void> { }; 36 37template<class _Tp, class _Up = _Tp> 38using compare_three_way_result_t = typename compare_three_way_result<_Tp, _Up>::type; 39 40#endif // _LIBCPP_STD_VER > 17 41 42_LIBCPP_END_NAMESPACE_STD 43 44#endif // _LIBCPP___COMPARE_COMPARE_THREE_WAY_RESULT_H 45