libstdc++
typeindex
Go to the documentation of this file.
1 // C++11 <typeindex> -*- C++ -*-
2 
3 // Copyright (C) 2010-2025 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 include/typeindex
26  * This is a Standard C++ Library header.
27  */
28 
29 #ifndef _GLIBCXX_TYPEINDEX
30 #define _GLIBCXX_TYPEINDEX 1
31 
32 #ifdef _GLIBCXX_SYSHDR
33 #pragma GCC system_header
34 #endif
35 
36 #if __cplusplus < 201103L
37 # include <bits/c++0x_warning.h>
38 #else
39 
40 #include <typeinfo>
41 #if __cplusplus > 201703L
42 # include <compare>
43 #endif
44 
45 namespace std _GLIBCXX_VISIBILITY(default)
46 {
47 _GLIBCXX_BEGIN_NAMESPACE_VERSION
48 
49  /**
50  * @brief Class type_index
51  * @ingroup utilities
52  *
53  * The class type_index provides a simple wrapper for type_info
54  * which can be used as an index type in associative containers
55  * (23.6) and in unordered associative containers (23.7).
56  */
57  struct type_index
58  {
59  type_index(const type_info& __rhs) noexcept
60  : _M_target(&__rhs) { }
61 
62  bool
63  operator==(const type_index& __rhs) const noexcept
64  { return *_M_target == *__rhs._M_target; }
65 
66 #if ! __cpp_lib_three_way_comparison
67  bool
68  operator!=(const type_index& __rhs) const noexcept
69  { return *_M_target != *__rhs._M_target; }
70 #endif
71 
72  bool
73  operator<(const type_index& __rhs) const noexcept
74  { return _M_target->before(*__rhs._M_target); }
75 
76  bool
77  operator<=(const type_index& __rhs) const noexcept
78  { return !__rhs._M_target->before(*_M_target); }
79 
80  bool
81  operator>(const type_index& __rhs) const noexcept
82  { return __rhs._M_target->before(*_M_target); }
83 
84  bool
85  operator>=(const type_index& __rhs) const noexcept
86  { return !_M_target->before(*__rhs._M_target); }
87 
88 #if __cpp_lib_three_way_comparison
89  strong_ordering
90  operator<=>(const type_index& __rhs) const noexcept
91  {
92  if (*_M_target == *__rhs._M_target)
93  return strong_ordering::equal;
94  if (_M_target->before(*__rhs._M_target))
95  return strong_ordering::less;
96  return strong_ordering::greater;
97  }
98 #endif
99 
100  size_t
101  hash_code() const noexcept
102  { return _M_target->hash_code(); }
103 
104  const char*
105  name() const noexcept
106  { return _M_target->name(); }
107 
108  private:
109  const type_info* _M_target;
110  };
111 
112  template<typename _Tp> struct hash;
113 
114  /// std::hash specialization for type_index.
115  template<>
116  struct hash<type_index>
117  {
118  typedef size_t result_type;
119  typedef type_index argument_type;
120 
121  size_t
122  operator()(const type_index& __ti) const noexcept
123  { return __ti.hash_code(); }
124  };
125 
126 _GLIBCXX_END_NAMESPACE_VERSION
127 } // namespace std
128 
129 #endif // C++11
130 
131 #endif // _GLIBCXX_TYPEINDEX