1 // Concept-constrained comparison implementations -*- C++ -*-
2
3 // Copyright (C) 2019-2020 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/range_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 _RANGE_CMP_H
31 #define _RANGE_CMP_H 1
32
33 #if __cplusplus > 201703L
34 # include <bits/move.h>
35 # include <concepts>
36
_GLIBCXX_VISIBILITY(default)37 namespace 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 constexpr _Tp&&
51 operator()(_Tp&& __t) const noexcept
52 { return std::forward<_Tp>(__t); }
53
54 using is_transparent = __is_transparent;
55 };
56
57 #ifdef __cpp_lib_concepts
58 // Define this here, included by all the headers that need to define it.
59 #define __cpp_lib_ranges 201911L
60
61 namespace ranges
62 {
63 namespace __detail
64 {
65 // BUILTIN-PTR-CMP(T, <, U)
66 // This determines whether t < u results in a call to a built-in operator<
67 // comparing pointers. It doesn't work for function pointers (PR 93628).
68 template<typename _Tp, typename _Up>
69 concept __less_builtin_ptr_cmp
70 = requires (_Tp&& __t, _Up&& __u) { { __t < __u } -> same_as<bool>; }
71 && convertible_to<_Tp, const volatile void*>
72 && convertible_to<_Up, const volatile void*>
73 && (! requires(_Tp&& __t, _Up&& __u)
74 { operator<(std::forward<_Tp>(__t), std::forward<_Up>(__u)); }
75 && ! requires(_Tp&& __t, _Up&& __u)
76 { std::forward<_Tp>(__t).operator<(std::forward<_Up>(__u)); });
77 } // namespace __detail
78
79 // [range.cmp] Concept-constrained comparisons
80
81 // _GLIBCXX_RESOLVE_LIB_DEFECTS
82 // 3530 BUILTIN-PTR-MEOW should not opt the type out of syntactic checks
83
84 /// ranges::equal_to function object type.
85 struct equal_to
86 {
87 template<typename _Tp, typename _Up>
88 requires equality_comparable_with<_Tp, _Up>
89 constexpr bool
90 operator()(_Tp&& __t, _Up&& __u) const
91 noexcept(noexcept(std::declval<_Tp>() == std::declval<_Up>()))
92 { return std::forward<_Tp>(__t) == std::forward<_Up>(__u); }
93
94 using is_transparent = __is_transparent;
95 };
96
97 /// ranges::not_equal_to function object type.
98 struct not_equal_to
99 {
100 template<typename _Tp, typename _Up>
101 requires equality_comparable_with<_Tp, _Up>
102 constexpr bool
103 operator()(_Tp&& __t, _Up&& __u) const
104 noexcept(noexcept(std::declval<_Up>() == std::declval<_Tp>()))
105 { return !equal_to{}(std::forward<_Tp>(__t), std::forward<_Up>(__u)); }
106
107 using is_transparent = __is_transparent;
108 };
109
110 /// ranges::less function object type.
111 struct less
112 {
113 template<typename _Tp, typename _Up>
114 requires totally_ordered_with<_Tp, _Up>
115 constexpr bool
116 operator()(_Tp&& __t, _Up&& __u) const
117 noexcept(noexcept(std::declval<_Tp>() < std::declval<_Up>()))
118 {
119 if constexpr (__detail::__less_builtin_ptr_cmp<_Tp, _Up>)
120 {
121 #ifdef __cpp_lib_is_constant_evaluated
122 if (std::is_constant_evaluated())
123 return __t < __u;
124 #endif
125 auto __x = reinterpret_cast<__UINTPTR_TYPE__>(
126 static_cast<const volatile void*>(std::forward<_Tp>(__t)));
127 auto __y = reinterpret_cast<__UINTPTR_TYPE__>(
128 static_cast<const volatile void*>(std::forward<_Up>(__u)));
129 return __x < __y;
130 }
131 else
132 return std::forward<_Tp>(__t) < std::forward<_Up>(__u);
133 }
134
135 using is_transparent = __is_transparent;
136 };
137
138 /// ranges::greater function object type.
139 struct greater
140 {
141 template<typename _Tp, typename _Up>
142 requires totally_ordered_with<_Tp, _Up>
143 constexpr bool
144 operator()(_Tp&& __t, _Up&& __u) const
145 noexcept(noexcept(std::declval<_Up>() < std::declval<_Tp>()))
146 { return less{}(std::forward<_Up>(__u), std::forward<_Tp>(__t)); }
147
148 using is_transparent = __is_transparent;
149 };
150
151 /// ranges::greater_equal function object type.
152 struct greater_equal
153 {
154 template<typename _Tp, typename _Up>
155 requires totally_ordered_with<_Tp, _Up>
156 constexpr bool
157 operator()(_Tp&& __t, _Up&& __u) const
158 noexcept(noexcept(std::declval<_Tp>() < std::declval<_Up>()))
159 { return !less{}(std::forward<_Tp>(__t), std::forward<_Up>(__u)); }
160
161 using is_transparent = __is_transparent;
162 };
163
164 /// ranges::less_equal function object type.
165 struct less_equal
166 {
167 template<typename _Tp, typename _Up>
168 requires totally_ordered_with<_Tp, _Up>
169 constexpr bool
170 operator()(_Tp&& __t, _Up&& __u) const
171 noexcept(noexcept(std::declval<_Up>() < std::declval<_Tp>()))
172 { return !less{}(std::forward<_Up>(__u), std::forward<_Tp>(__t)); }
173
174 using is_transparent = __is_transparent;
175 };
176
177 } // namespace ranges
178 #endif // library concepts
179 _GLIBCXX_END_NAMESPACE_VERSION
180 } // namespace std
181 #endif // C++20
182 #endif // _RANGE_CMP_H
183