1// -*- C++ -*-
 2//===----------------------------------------------------------------------===//
 3//
 4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 5// See https://llvm.org/LICENSE.txt for license information.
 6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 7//
 8//===----------------------------------------------------------------------===//
 9
10#ifndef _LIBCPP___COMPARE_COMPARE_THREE_WAY_H
11#define _LIBCPP___COMPARE_COMPARE_THREE_WAY_H
12
13#include <__compare/three_way_comparable.h>
14#include <__config>
15#include <__utility/forward.h>
16
17#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
18#  pragma GCC system_header
19#endif
20
21_LIBCPP_BEGIN_NAMESPACE_STD
22
23#if _LIBCPP_STD_VER >= 20
24
25struct compare_three_way {
26  template <class _T1, class _T2>
27    requires three_way_comparable_with<_T1, _T2>
28  constexpr _LIBCPP_HIDE_FROM_ABI auto operator()(_T1&& __t, _T2&& __u) const
29      noexcept(noexcept(std::forward<_T1>(__t) <=> std::forward<_T2>(__u))) {
30    return std::forward<_T1>(__t) <=> std::forward<_T2>(__u);
31  }
32
33  using is_transparent = void;
34};
35
36#endif // _LIBCPP_STD_VER >= 20
37
38_LIBCPP_END_NAMESPACE_STD
39
40#endif // _LIBCPP___COMPARE_COMPARE_THREE_WAY_H