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 
25 struct _LIBCPP_TEMPLATE_VIS compare_three_way {
26   template <class _T1, class _T2>
27     requires three_way_comparable_with<_T1, _T2>
operatorcompare_three_way28   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
41