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 
22 template <class _Compare>
23 struct __debug_less
24 {
25     _Compare &__comp_;
26     _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI __debug_less(_Compare& __c) : __comp_(__c) {}
27 
28     template <class _Tp, class _Up>
29     _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI
30     bool operator()(const _Tp& __x,  const _Up& __y)
31     {
32         bool __r = __comp_(__x, __y);
33         if (__r)
34             __do_compare_assert(0, __y, __x);
35         return __r;
36     }
37 
38     template <class _Tp, class _Up>
39     _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI
40     bool operator()(_Tp& __x,  _Up& __y)
41     {
42         bool __r = __comp_(__x, __y);
43         if (__r)
44             __do_compare_assert(0, __y, __x);
45         return __r;
46     }
47 
48     template <class _LHS, class _RHS>
49     _LIBCPP_CONSTEXPR_SINCE_CXX14
50     inline _LIBCPP_INLINE_VISIBILITY
51     decltype((void)std::declval<_Compare&>()(
52         std::declval<_LHS &>(), std::declval<_RHS &>()))
53     __do_compare_assert(int, _LHS & __l, _RHS & __r) {
54         _LIBCPP_ASSERT_UNCATEGORIZED(!__comp_(__l, __r),
55             "Comparator does not induce a strict weak ordering");
56         (void)__l;
57         (void)__r;
58     }
59 
60     template <class _LHS, class _RHS>
61     _LIBCPP_CONSTEXPR_SINCE_CXX14
62     inline _LIBCPP_INLINE_VISIBILITY
63     void __do_compare_assert(long, _LHS &, _RHS &) {}
64 };
65 
66 // Pass the comparator by lvalue reference. Or in debug mode, using a
67 // debugging wrapper that stores a reference.
68 #if _LIBCPP_ENABLE_DEBUG_MODE
69 template <class _Comp>
70 using __comp_ref_type = __debug_less<_Comp>;
71 #else
72 template <class _Comp>
73 using __comp_ref_type = _Comp&;
74 #endif
75 
76 _LIBCPP_END_NAMESPACE_STD
77 
78 #endif // _LIBCPP___ALGORITHM_COMP_REF_TYPE_H
79