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___ALGORITHM_COMP_REF_TYPE_H
10#define _LIBCPP___ALGORITHM_COMP_REF_TYPE_H
11
12#include <__assert>
13#include <__config>
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
22template <class _Compare>
23struct __debug_less {
24  _Compare& __comp_;
25  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI __debug_less(_Compare& __c) : __comp_(__c) {}
26
27  template <class _Tp, class _Up>
28  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI bool operator()(const _Tp& __x, const _Up& __y) {
29    bool __r = __comp_(__x, __y);
30    if (__r)
31      __do_compare_assert(0, __y, __x);
32    return __r;
33  }
34
35  template <class _Tp, class _Up>
36  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI bool operator()(_Tp& __x, _Up& __y) {
37    bool __r = __comp_(__x, __y);
38    if (__r)
39      __do_compare_assert(0, __y, __x);
40    return __r;
41  }
42
43  template <class _LHS, class _RHS>
44  _LIBCPP_CONSTEXPR_SINCE_CXX14 inline _LIBCPP_HIDE_FROM_ABI decltype((void)std::declval<_Compare&>()(
45      std::declval<_LHS&>(), std::declval<_RHS&>()))
46  __do_compare_assert(int, _LHS& __l, _RHS& __r) {
47    _LIBCPP_ASSERT_SEMANTIC_REQUIREMENT(!__comp_(__l, __r), "Comparator does not induce a strict weak ordering");
48    (void)__l;
49    (void)__r;
50  }
51
52  template <class _LHS, class _RHS>
53  _LIBCPP_CONSTEXPR_SINCE_CXX14 inline _LIBCPP_HIDE_FROM_ABI void __do_compare_assert(long, _LHS&, _RHS&) {}
54};
55
56// Pass the comparator by lvalue reference. Or in the debug mode, using a debugging wrapper that stores a reference.
57#if _LIBCPP_HARDENING_MODE == _LIBCPP_HARDENING_MODE_DEBUG
58template <class _Comp>
59using __comp_ref_type = __debug_less<_Comp>;
60#else
61template <class _Comp>
62using __comp_ref_type = _Comp&;
63#endif
64
65_LIBCPP_END_NAMESPACE_STD
66
67#endif // _LIBCPP___ALGORITHM_COMP_REF_TYPE_H
68