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 <__config>
13#include <__debug>
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{
25    _Compare &__comp_;
26    _LIBCPP_CONSTEXPR_SINCE_CXX14
27    __debug_less(_Compare& __c) : __comp_(__c) {}
28
29    template <class _Tp, class _Up>
30    _LIBCPP_CONSTEXPR_SINCE_CXX14
31    bool operator()(const _Tp& __x,  const _Up& __y)
32    {
33        bool __r = __comp_(__x, __y);
34        if (__r)
35            __do_compare_assert(0, __y, __x);
36        return __r;
37    }
38
39    template <class _Tp, class _Up>
40    _LIBCPP_CONSTEXPR_SINCE_CXX14
41    bool operator()(_Tp& __x,  _Up& __y)
42    {
43        bool __r = __comp_(__x, __y);
44        if (__r)
45            __do_compare_assert(0, __y, __x);
46        return __r;
47    }
48
49    template <class _LHS, class _RHS>
50    _LIBCPP_CONSTEXPR_SINCE_CXX14
51    inline _LIBCPP_INLINE_VISIBILITY
52    decltype((void)std::declval<_Compare&>()(
53        std::declval<_LHS &>(), std::declval<_RHS &>()))
54    __do_compare_assert(int, _LHS & __l, _RHS & __r) {
55        _LIBCPP_DEBUG_ASSERT(!__comp_(__l, __r),
56            "Comparator does not induce a strict weak ordering");
57        (void)__l;
58        (void)__r;
59    }
60
61    template <class _LHS, class _RHS>
62    _LIBCPP_CONSTEXPR_SINCE_CXX14
63    inline _LIBCPP_INLINE_VISIBILITY
64    void __do_compare_assert(long, _LHS &, _RHS &) {}
65};
66
67// Pass the comparator by lvalue reference. Or in debug mode, using a
68// debugging wrapper that stores a reference.
69#ifdef _LIBCPP_ENABLE_DEBUG_MODE
70template <class _Comp>
71using __comp_ref_type = __debug_less<_Comp>;
72#else
73template <class _Comp>
74using __comp_ref_type = _Comp&;
75#endif
76
77_LIBCPP_END_NAMESPACE_STD
78
79#endif // _LIBCPP___ALGORITHM_COMP_REF_TYPE_H
80