1// Concept-constrained comparison implementations -*- C++ -*- 
2 
3// Copyright (C) 2019-2021 Free Software Foundation, Inc. 
4// 
5// This file is part of the GNU ISO C++ Library. This library is free 
6// software; you can redistribute it and/or modify it under the 
7// terms of the GNU General Public License as published by the 
8// Free Software Foundation; either version 3, or (at your option) 
9// any later version. 
10 
11// This library is distributed in the hope that it will be useful, 
12// but WITHOUT ANY WARRANTY; without even the implied warranty of 
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
14// GNU General Public License for more details. 
15 
16// Under Section 7 of GPL version 3, you are granted additional 
17// permissions described in the GCC Runtime Library Exception, version 
18// 3.1, as published by the Free Software Foundation. 
19 
20// You should have received a copy of the GNU General Public License and 
21// a copy of the GCC Runtime Library Exception along with this program; 
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 
23// <http://www.gnu.org/licenses/>. 
24 
25/** @file bits/ranges_cmp.h 
26 * This is an internal header file, included by other library headers. 
27 * Do not attempt to use it directly. @headername{functional} 
28 */ 
29 
30#ifndef _RANGES_CMP_H 
31#define _RANGES_CMP_H 1 
32 
33#if __cplusplus > 201703L 
34# include <bits/move.h> 
35# include <concepts> 
36 
37namespace std _GLIBCXX_VISIBILITY(default) 
38{ 
39_GLIBCXX_BEGIN_NAMESPACE_VERSION 
40 
41 struct __is_transparent; // not defined 
42 
43 // Define std::identity here so that <iterator> and <ranges> 
44 // don't need to include <bits/stl_function.h> to get it. 
45 
46 /// [func.identity] The identity function. 
47 struct identity 
48 { 
49 template<typename _Tp> 
50 [[nodiscard]] 
51 constexpr _Tp&& 
52 operator()(_Tp&& __t) const noexcept 
53 { return std::forward<_Tp>(__t); } 
54 
55 using is_transparent = __is_transparent; 
56 }; 
57 
58#ifdef __cpp_lib_concepts 
59// Define this here, included by all the headers that need to define it. 
60#define __cpp_lib_ranges 202106L 
61 
62namespace ranges 
63{ 
64 namespace __detail 
65 { 
66 // BUILTIN-PTR-CMP(T, <, U) 
67 // This determines whether t < u results in a call to a built-in operator< 
68 // comparing pointers. It doesn't work for function pointers (PR 93628). 
69 template<typename _Tp, typename _Up> 
70 concept __less_builtin_ptr_cmp 
71 = requires (_Tp&& __t, _Up&& __u) { { __t < __u } -> same_as<bool>; } 
72 && convertible_to<_Tp, const volatile void*> 
73 && convertible_to<_Up, const volatile void*> 
74 && (! requires(_Tp&& __t, _Up&& __u) 
75 { operator<(std::forward<_Tp>(__t), std::forward<_Up>(__u)); } 
76 && ! requires(_Tp&& __t, _Up&& __u) 
77 { std::forward<_Tp>(__t).operator<(std::forward<_Up>(__u)); }); 
78 } // namespace __detail 
79 
80 // [range.cmp] Concept-constrained comparisons 
81 
82 // _GLIBCXX_RESOLVE_LIB_DEFECTS 
83 // 3530 BUILTIN-PTR-MEOW should not opt the type out of syntactic checks 
84 
85 /// ranges::equal_to function object type. 
86 struct equal_to 
87 { 
88 template<typename _Tp, typename _Up> 
89 requires equality_comparable_with<_Tp, _Up> 
90 constexpr bool 
91 operator()(_Tp&& __t, _Up&& __u) const 
92 noexcept(noexcept(std::declval<_Tp>() == std::declval<_Up>())) 
93 { return std::forward<_Tp>(__t) == std::forward<_Up>(__u); } 
94 
95 using is_transparent = __is_transparent; 
96 }; 
97 
98 /// ranges::not_equal_to function object type. 
99 struct not_equal_to 
100 { 
101 template<typename _Tp, typename _Up> 
102 requires equality_comparable_with<_Tp, _Up> 
103 constexpr bool 
104 operator()(_Tp&& __t, _Up&& __u) const 
105 noexcept(noexcept(std::declval<_Up>() == std::declval<_Tp>())) 
106 { return !equal_to{}(std::forward<_Tp>(__t), std::forward<_Up>(__u)); } 
107 
108 using is_transparent = __is_transparent; 
109 }; 
110 
111 /// ranges::less function object type. 
112 struct less 
113 { 
114 template<typename _Tp, typename _Up> 
115 requires totally_ordered_with<_Tp, _Up> 
116 constexpr bool 
117 operator()(_Tp&& __t, _Up&& __u) const 
118 noexcept(noexcept(std::declval<_Tp>() < std::declval<_Up>())) 
119 { 
120 if constexpr (__detail::__less_builtin_ptr_cmp<_Tp, _Up>) 
121 { 
122#ifdef __cpp_lib_is_constant_evaluated 
123 if (std::is_constant_evaluated()) 
124 return __t < __u; 
125#endif 
126 auto __x = reinterpret_cast<__UINTPTR_TYPE__>( 
127 static_cast<const volatile void*>(std::forward<_Tp>(__t))); 
128 auto __y = reinterpret_cast<__UINTPTR_TYPE__>( 
129 static_cast<const volatile void*>(std::forward<_Up>(__u))); 
130 return __x < __y; 
131 } 
132 else 
133 return std::forward<_Tp>(__t) < std::forward<_Up>(__u); 
134 } 
135 
136 using is_transparent = __is_transparent; 
137 }; 
138 
139 /// ranges::greater function object type. 
140 struct greater 
141 { 
142 template<typename _Tp, typename _Up> 
143 requires totally_ordered_with<_Tp, _Up> 
144 constexpr bool 
145 operator()(_Tp&& __t, _Up&& __u) const 
146 noexcept(noexcept(std::declval<_Up>() < std::declval<_Tp>())) 
147 { return less{}(std::forward<_Up>(__u), std::forward<_Tp>(__t)); } 
148 
149 using is_transparent = __is_transparent; 
150 }; 
151 
152 /// ranges::greater_equal function object type. 
153 struct greater_equal 
154 { 
155 template<typename _Tp, typename _Up> 
156 requires totally_ordered_with<_Tp, _Up> 
157 constexpr bool 
158 operator()(_Tp&& __t, _Up&& __u) const 
159 noexcept(noexcept(std::declval<_Tp>() < std::declval<_Up>())) 
160 { return !less{}(std::forward<_Tp>(__t), std::forward<_Up>(__u)); } 
161 
162 using is_transparent = __is_transparent; 
163 }; 
164 
165 /// ranges::less_equal function object type. 
166 struct less_equal 
167 { 
168 template<typename _Tp, typename _Up> 
169 requires totally_ordered_with<_Tp, _Up> 
170 constexpr bool 
171 operator()(_Tp&& __t, _Up&& __u) const 
172 noexcept(noexcept(std::declval<_Up>() < std::declval<_Tp>())) 
173 { return !less{}(std::forward<_Up>(__u), std::forward<_Tp>(__t)); } 
174 
175 using is_transparent = __is_transparent; 
176 }; 
177 
178} // namespace ranges 
179#endif // library concepts 
180_GLIBCXX_END_NAMESPACE_VERSION 
181} // namespace std 
182#endif // C++20 
183#endif // _RANGES_CMP_H 
184