libstdc++
range_cmp.h
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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 
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  template<typename _Tp, typename _Up>
67  concept __eq_builtin_ptr_cmp
68  = requires (_Tp&& __t, _Up&& __u) { { __t == __u } -> same_as<bool>; }
69  && convertible_to<_Tp, const volatile void*>
70  && convertible_to<_Up, const volatile void*>
71  && (! requires(_Tp&& __t, _Up&& __u)
72  { operator==(std::forward<_Tp>(__t), std::forward<_Up>(__u)); }
73  &&
74  ! requires(_Tp&& __t, _Up&& __u)
75  { std::forward<_Tp>(__t).operator==(std::forward<_Up>(__u)); });
76 
77  // BUILTIN-PTR-CMP(T, <, U)
78  template<typename _Tp, typename _Up>
79  concept __less_builtin_ptr_cmp
80  = requires (_Tp&& __t, _Up&& __u) { { __t < __u } -> same_as<bool>; }
81  && convertible_to<_Tp, const volatile void*>
82  && convertible_to<_Up, const volatile void*>
83  && (! requires(_Tp&& __t, _Up&& __u)
84  { operator<(std::forward<_Tp>(__t), std::forward<_Up>(__u)); }
85  && ! requires(_Tp&& __t, _Up&& __u)
86  { std::forward<_Tp>(__t).operator<(std::forward<_Up>(__u)); });
87  } // namespace __detail
88 
89  // [range.cmp] Concept-constrained comparisons
90 
91  /// ranges::equal_to function object type.
92  struct equal_to
93  {
94  template<typename _Tp, typename _Up>
95  requires equality_comparable_with<_Tp, _Up>
96  || __detail::__eq_builtin_ptr_cmp<_Tp, _Up>
97  constexpr bool
98  operator()(_Tp&& __t, _Up&& __u) const
99  noexcept(noexcept(std::declval<_Tp>() == std::declval<_Up>()))
100  { return std::forward<_Tp>(__t) == std::forward<_Up>(__u); }
101 
102  using is_transparent = __is_transparent;
103  };
104 
105  /// ranges::not_equal_to function object type.
106  struct not_equal_to
107  {
108  template<typename _Tp, typename _Up>
109  requires equality_comparable_with<_Tp, _Up>
110  || __detail::__eq_builtin_ptr_cmp<_Tp, _Up>
111  constexpr bool
112  operator()(_Tp&& __t, _Up&& __u) const
113  noexcept(noexcept(std::declval<_Up>() == std::declval<_Tp>()))
114  { return !equal_to{}(std::forward<_Tp>(__t), std::forward<_Up>(__u)); }
115 
116  using is_transparent = __is_transparent;
117  };
118 
119  /// ranges::less function object type.
120  struct less
121  {
122  template<typename _Tp, typename _Up>
123  requires totally_ordered_with<_Tp, _Up>
124  || __detail::__less_builtin_ptr_cmp<_Tp, _Up>
125  constexpr bool
126  operator()(_Tp&& __t, _Up&& __u) const
127  noexcept(noexcept(std::declval<_Tp>() < std::declval<_Up>()))
128  {
129  if constexpr (__detail::__less_builtin_ptr_cmp<_Tp, _Up>)
130  {
131 #ifdef __cpp_lib_is_constant_evaluated
132  if (std::is_constant_evaluated())
133  return __t < __u;
134 #endif
135  auto __x = reinterpret_cast<__UINTPTR_TYPE__>(
136  static_cast<const volatile void*>(std::forward<_Tp>(__t)));
137  auto __y = reinterpret_cast<__UINTPTR_TYPE__>(
138  static_cast<const volatile void*>(std::forward<_Up>(__u)));
139  return __x < __y;
140  }
141  else
142  return std::forward<_Tp>(__t) < std::forward<_Up>(__u);
143  }
144 
145  using is_transparent = __is_transparent;
146  };
147 
148  /// ranges::greater function object type.
149  struct greater
150  {
151  template<typename _Tp, typename _Up>
152  requires totally_ordered_with<_Tp, _Up>
153  || __detail::__less_builtin_ptr_cmp<_Up, _Tp>
154  constexpr bool
155  operator()(_Tp&& __t, _Up&& __u) const
156  noexcept(noexcept(std::declval<_Up>() < std::declval<_Tp>()))
157  { return less{}(std::forward<_Up>(__u), std::forward<_Tp>(__t)); }
158 
159  using is_transparent = __is_transparent;
160  };
161 
162  /// ranges::greater_equal function object type.
163  struct greater_equal
164  {
165  template<typename _Tp, typename _Up>
166  requires totally_ordered_with<_Tp, _Up>
167  || __detail::__less_builtin_ptr_cmp<_Tp, _Up>
168  constexpr bool
169  operator()(_Tp&& __t, _Up&& __u) const
170  noexcept(noexcept(std::declval<_Tp>() < std::declval<_Up>()))
171  { return !less{}(std::forward<_Tp>(__t), std::forward<_Up>(__u)); }
172 
173  using is_transparent = __is_transparent;
174  };
175 
176  /// ranges::less_equal function object type.
177  struct less_equal
178  {
179  template<typename _Tp, typename _Up>
180  requires totally_ordered_with<_Tp, _Up>
181  || __detail::__less_builtin_ptr_cmp<_Up, _Tp>
182  constexpr bool
183  operator()(_Tp&& __t, _Up&& __u) const
184  noexcept(noexcept(std::declval<_Up>() < std::declval<_Tp>()))
185  { return !less{}(std::forward<_Up>(__u), std::forward<_Tp>(__t)); }
186 
187  using is_transparent = __is_transparent;
188  };
189 
190 } // namespace ranges
191 #endif // library concepts
192 _GLIBCXX_END_NAMESPACE_VERSION
193 } // namespace std
194 #endif // C++20
195 #endif // _RANGE_CMP_H