libstdc++
ranges_cmp.h
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1 // Concept-constrained comparison implementations -*- C++ -*-
2 
3 // Copyright (C) 2019-2023 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 
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  [[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 #if __cplusplus > 202002L
61 #define __cpp_lib_ranges 202202L
62 #else
63 #define __cpp_lib_ranges 202110L
64 #endif
65 
66 namespace ranges
67 {
68  namespace __detail
69  {
70  // BUILTIN-PTR-CMP(T, <, U)
71  // This determines whether t < u results in a call to a built-in operator<
72  // comparing pointers. It doesn't work for function pointers (PR 93628).
73  template<typename _Tp, typename _Up>
74  concept __less_builtin_ptr_cmp
75  = requires (_Tp&& __t, _Up&& __u) { { __t < __u } -> same_as<bool>; }
76  && convertible_to<_Tp, const volatile void*>
77  && convertible_to<_Up, const volatile void*>
78  && (! requires(_Tp&& __t, _Up&& __u)
79  { operator<(std::forward<_Tp>(__t), std::forward<_Up>(__u)); }
80  && ! requires(_Tp&& __t, _Up&& __u)
81  { std::forward<_Tp>(__t).operator<(std::forward<_Up>(__u)); });
82  } // namespace __detail
83 
84  // [range.cmp] Concept-constrained comparisons
85 
86  // _GLIBCXX_RESOLVE_LIB_DEFECTS
87  // 3530 BUILTIN-PTR-MEOW should not opt the type out of syntactic checks
88 
89  /// ranges::equal_to function object type.
90  struct equal_to
91  {
92  template<typename _Tp, typename _Up>
93  requires equality_comparable_with<_Tp, _Up>
94  constexpr bool
95  operator()(_Tp&& __t, _Up&& __u) const
96  noexcept(noexcept(std::declval<_Tp>() == std::declval<_Up>()))
97  { return std::forward<_Tp>(__t) == std::forward<_Up>(__u); }
98 
99  using is_transparent = __is_transparent;
100  };
101 
102  /// ranges::not_equal_to function object type.
104  {
105  template<typename _Tp, typename _Up>
106  requires equality_comparable_with<_Tp, _Up>
107  constexpr bool
108  operator()(_Tp&& __t, _Up&& __u) const
109  noexcept(noexcept(std::declval<_Up>() == std::declval<_Tp>()))
110  { return !equal_to{}(std::forward<_Tp>(__t), std::forward<_Up>(__u)); }
111 
112  using is_transparent = __is_transparent;
113  };
114 
115  /// ranges::less function object type.
116  struct less
117  {
118  template<typename _Tp, typename _Up>
119  requires totally_ordered_with<_Tp, _Up>
120  constexpr bool
121  operator()(_Tp&& __t, _Up&& __u) const
122  noexcept(noexcept(std::declval<_Tp>() < std::declval<_Up>()))
123  {
124  if constexpr (__detail::__less_builtin_ptr_cmp<_Tp, _Up>)
125  {
126  if (std::__is_constant_evaluated())
127  return __t < __u;
128 
129  auto __x = reinterpret_cast<__UINTPTR_TYPE__>(
130  static_cast<const volatile void*>(std::forward<_Tp>(__t)));
131  auto __y = reinterpret_cast<__UINTPTR_TYPE__>(
132  static_cast<const volatile void*>(std::forward<_Up>(__u)));
133  return __x < __y;
134  }
135  else
136  return std::forward<_Tp>(__t) < std::forward<_Up>(__u);
137  }
138 
139  using is_transparent = __is_transparent;
140  };
141 
142  /// ranges::greater function object type.
143  struct greater
144  {
145  template<typename _Tp, typename _Up>
146  requires totally_ordered_with<_Tp, _Up>
147  constexpr bool
148  operator()(_Tp&& __t, _Up&& __u) const
149  noexcept(noexcept(std::declval<_Up>() < std::declval<_Tp>()))
150  { return less{}(std::forward<_Up>(__u), std::forward<_Tp>(__t)); }
151 
152  using is_transparent = __is_transparent;
153  };
154 
155  /// ranges::greater_equal function object type.
157  {
158  template<typename _Tp, typename _Up>
159  requires totally_ordered_with<_Tp, _Up>
160  constexpr bool
161  operator()(_Tp&& __t, _Up&& __u) const
162  noexcept(noexcept(std::declval<_Tp>() < std::declval<_Up>()))
163  { return !less{}(std::forward<_Tp>(__t), std::forward<_Up>(__u)); }
164 
165  using is_transparent = __is_transparent;
166  };
167 
168  /// ranges::less_equal function object type.
169  struct less_equal
170  {
171  template<typename _Tp, typename _Up>
172  requires totally_ordered_with<_Tp, _Up>
173  constexpr bool
174  operator()(_Tp&& __t, _Up&& __u) const
175  noexcept(noexcept(std::declval<_Up>() < std::declval<_Tp>()))
176  { return !less{}(std::forward<_Up>(__u), std::forward<_Tp>(__t)); }
177 
178  using is_transparent = __is_transparent;
179  };
180 
181 } // namespace ranges
182 #endif // library concepts
183 _GLIBCXX_END_NAMESPACE_VERSION
184 } // namespace std
185 #endif // C++20
186 #endif // _RANGES_CMP_H
[func.identity] The identity function.
Definition: ranges_cmp.h:47
ranges::greater_equal function object type.
Definition: ranges_cmp.h:156
Definition: simd.h:281
ranges::not_equal_to function object type.
Definition: ranges_cmp.h:103
ranges::greater function object type.
Definition: ranges_cmp.h:143
ranges::equal_to function object type.
Definition: ranges_cmp.h:90
ranges::less_equal function object type.
Definition: ranges_cmp.h:169
ranges::less function object type.
Definition: ranges_cmp.h:116
ISO C++ entities toplevel namespace is std.