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The C and C++ Include Header Files
cat -n /usr/include/c++/15/bits/allocator.h
1 // Allocators -*- C++ -*- 2 3 // Copyright (C) 2001-2025 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 /* 26 * Copyright (c) 1996-1997 27 * Silicon Graphics Computer Systems, Inc. 28 * 29 * Permission to use, copy, modify, distribute and sell this software 30 * and its documentation for any purpose is hereby granted without fee, 31 * provided that the above copyright notice appear in all copies and 32 * that both that copyright notice and this permission notice appear 33 * in supporting documentation. Silicon Graphics makes no 34 * representations about the suitability of this software for any 35 * purpose. It is provided "as is" without express or implied warranty. 36 */ 37 38 /** @file bits/allocator.h 39 * This is an internal header file, included by other library headers. 40 * Do not attempt to use it directly. @headername{memory} 41 */ 42 43 #ifndef _ALLOCATOR_H 44 #define _ALLOCATOR_H 1 45 46 #include <bits/c++allocator.h> // Define the base class to std::allocator. 47 #include <bits/memoryfwd.h> 48 #if __cplusplus >= 201103L 49 #include <type_traits> 50 #endif 51 52 #pragma GCC diagnostic push 53 #pragma GCC diagnostic ignored "-Wc++11-extensions" 54 55 namespace std _GLIBCXX_VISIBILITY(default) 56 { 57 _GLIBCXX_BEGIN_NAMESPACE_VERSION 58 59 /** 60 * @addtogroup allocators 61 * @{ 62 */ 63 64 // Since C++20 the primary template should be used for allocator<void>, 65 // but then it would have a non-trivial default ctor and dtor for C++20, 66 // but trivial for C++98-17, which would be an ABI incompatibility between 67 // different standard dialects. So C++20 still uses the allocator<void> 68 // explicit specialization, with the historical ABI properties, but with 69 // the same members that are present in the primary template. 70 71 /** std::allocator<void> specialization. 72 * 73 * @headerfile memory 74 */ 75 template<> 76 class allocator<void> 77 { 78 public: 79 typedef void value_type; 80 typedef size_t size_type; 81 typedef ptrdiff_t difference_type; 82 83 #if __cplusplus <= 201703L 84 // These were removed for C++20, allocator_traits does the right thing. 85 typedef void* pointer; 86 typedef const void* const_pointer; 87 88 template<typename _Tp1> 89 struct rebind 90 { typedef allocator<_Tp1> other; }; 91 #endif 92 93 #if __cplusplus >= 201103L 94 // _GLIBCXX_RESOLVE_LIB_DEFECTS 95 // 2103. std::allocator propagate_on_container_move_assignment 96 using propagate_on_container_move_assignment = true_type; 97 98 #if __cplusplus <= 202302L 99 using is_always_equal 100 _GLIBCXX20_DEPRECATED_SUGGEST("std::allocator_traits::is_always_equal") 101 = true_type; 102 #endif 103 104 #if __cplusplus >= 202002L 105 // As noted above, these members are present for C++20 to provide the 106 // same API as the primary template, but still trivial as in pre-C++20. 107 allocator() = default; 108 ~allocator() = default; 109 110 template<typename _Up> 111 __attribute__((__always_inline__)) 112 constexpr 113 allocator(const allocator<_Up>&) noexcept { } 114 115 // No allocate member because it's ill-formed by LWG 3307. 116 // No deallocate member because it would be undefined to call it 117 // with any pointer which wasn't obtained from allocate. 118 #endif // C++20 119 #endif // C++11 120 }; 121 122 /** 123 * @brief The @a standard allocator, as per C++03 [20.4.1]. 124 * 125 * See https://gcc.gnu.org/onlinedocs/libstdc++/manual/memory.html#std.util.memory.allocator 126 * for further details. 127 * 128 * @tparam _Tp Type of allocated object. 129 * 130 * @headerfile memory 131 */ 132 template<typename _Tp> 133 class allocator : public __allocator_base<_Tp> 134 { 135 public: 136 typedef _Tp value_type; 137 typedef size_t size_type; 138 typedef ptrdiff_t difference_type; 139 140 #if __cplusplus <= 201703L 141 // These were removed for C++20. 142 typedef _Tp* pointer; 143 typedef const _Tp* const_pointer; 144 typedef _Tp& reference; 145 typedef const _Tp& const_reference; 146 147 template<typename _Tp1> 148 struct rebind 149 { typedef allocator<_Tp1> other; }; 150 #endif 151 152 #if __cplusplus >= 201103L 153 // _GLIBCXX_RESOLVE_LIB_DEFECTS 154 // 2103. std::allocator propagate_on_container_move_assignment 155 using propagate_on_container_move_assignment = true_type; 156 157 #if __cplusplus <= 202302L 158 using is_always_equal 159 _GLIBCXX20_DEPRECATED_SUGGEST("std::allocator_traits::is_always_equal") 160 = true_type; 161 #endif 162 #endif 163 164 // _GLIBCXX_RESOLVE_LIB_DEFECTS 165 // 3035. std::allocator's constructors should be constexpr 166 __attribute__((__always_inline__)) 167 _GLIBCXX20_CONSTEXPR 168 allocator() _GLIBCXX_NOTHROW { } 169 170 __attribute__((__always_inline__)) 171 _GLIBCXX20_CONSTEXPR 172 allocator(const allocator& __a) _GLIBCXX_NOTHROW 173 : __allocator_base<_Tp>(__a) { } 174 175 #if __cplusplus >= 201103L 176 // Avoid implicit deprecation. 177 allocator& operator=(const allocator&) = default; 178 #endif 179 180 template<typename _Tp1> 181 __attribute__((__always_inline__)) 182 _GLIBCXX20_CONSTEXPR 183 allocator(const allocator<_Tp1>&) _GLIBCXX_NOTHROW { } 184 185 __attribute__((__always_inline__)) 186 #if __cpp_constexpr_dynamic_alloc 187 constexpr 188 #endif 189 ~allocator() _GLIBCXX_NOTHROW { } 190 191 #if __cplusplus > 201703L 192 [[nodiscard,__gnu__::__always_inline__]] 193 constexpr _Tp* 194 allocate(size_t __n) 195 { 196 if (std::__is_constant_evaluated()) 197 { 198 if (__builtin_mul_overflow(__n, sizeof(_Tp), &__n)) 199 std::__throw_bad_array_new_length(); 200 return static_cast<_Tp*>(::operator new(__n)); 201 } 202 203 return __allocator_base<_Tp>::allocate(__n, 0); 204 } 205 206 [[__gnu__::__always_inline__]] 207 constexpr void 208 deallocate(_Tp* __p, size_t __n) 209 { 210 if (std::__is_constant_evaluated()) 211 { 212 ::operator delete(__p); 213 return; 214 } 215 __allocator_base<_Tp>::deallocate(__p, __n); 216 } 217 #endif // C++20 218 219 friend __attribute__((__always_inline__)) _GLIBCXX20_CONSTEXPR 220 bool 221 operator==(const allocator&, const allocator&) _GLIBCXX_NOTHROW 222 { return true; } 223 224 #if __cpp_impl_three_way_comparison < 201907L 225 friend __attribute__((__always_inline__)) _GLIBCXX20_CONSTEXPR 226 bool 227 operator!=(const allocator&, const allocator&) _GLIBCXX_NOTHROW 228 { return false; } 229 #endif 230 231 // Inherit everything else. 232 }; 233 234 /** Equality comparison for std::allocator objects 235 * 236 * @return true, for all std::allocator objects. 237 * @relates std::allocator 238 */ 239 template<typename _T1, typename _T2> 240 __attribute__((__always_inline__)) 241 inline _GLIBCXX20_CONSTEXPR bool 242 operator==(const allocator<_T1>&, const allocator<_T2>&) 243 _GLIBCXX_NOTHROW 244 { return true; } 245 246 #if __cpp_impl_three_way_comparison < 201907L 247 template<typename _T1, typename _T2> 248 __attribute__((__always_inline__)) 249 inline _GLIBCXX20_CONSTEXPR bool 250 operator!=(const allocator<_T1>&, const allocator<_T2>&) 251 _GLIBCXX_NOTHROW 252 { return false; } 253 #endif 254 255 /// @cond undocumented 256 257 // Invalid allocator<cv T> partial specializations. 258 // allocator_traits::rebind_alloc can be used to form a valid allocator type. 259 template<typename _Tp> 260 class allocator<const _Tp> 261 { 262 public: 263 typedef _Tp value_type; 264 allocator() { } 265 template<typename _Up> allocator(const allocator<_Up>&) { } 266 }; 267 268 template<typename _Tp> 269 class allocator<volatile _Tp> 270 { 271 public: 272 typedef _Tp value_type; 273 allocator() { } 274 template<typename _Up> allocator(const allocator<_Up>&) { } 275 }; 276 277 template<typename _Tp> 278 class allocator<const volatile _Tp> 279 { 280 public: 281 typedef _Tp value_type; 282 allocator() { } 283 template<typename _Up> allocator(const allocator<_Up>&) { } 284 }; 285 /// @endcond 286 287 /// @} group allocator 288 289 // Inhibit implicit instantiations for required instantiations, 290 // which are defined via explicit instantiations elsewhere. 291 #if _GLIBCXX_EXTERN_TEMPLATE 292 extern template class allocator<char>; 293 extern template class allocator<wchar_t>; 294 #endif 295 296 // Undefine. 297 #undef __allocator_base 298 299 _GLIBCXX_END_NAMESPACE_VERSION 300 } // namespace std 301 302 #pragma GCC diagnostic pop 303 #endif
