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The C and C++ Include Header Files
/usr/include/c++/11/bits/allocator.h
$ cat -n /usr/include/c++/11/bits/allocator.h 1 // Allocators -*- C++ -*- 2 3 // Copyright (C) 2001-2021 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 #define __cpp_lib_incomplete_container_elements 201505 53 54 namespace std _GLIBCXX_VISIBILITY(default) 55 { 56 _GLIBCXX_BEGIN_NAMESPACE_VERSION 57 58 /** 59 * @addtogroup allocators 60 * @{ 61 */ 62 63 // Since C++20 the primary template should be used for allocator<void>, 64 // but then it would have a non-trivial default ctor and dtor for C++20, 65 // but trivial for C++98-17, which would be an ABI incompatibiliy between 66 // different standard dialects. So C++20 still uses the allocator<void> 67 // explicit specialization, with the historical ABI properties, but with 68 // the same members that are present in the primary template. 69 70 /// allocator<void> specialization. 71 template<> 72 class allocator<void> 73 { 74 public: 75 typedef void value_type; 76 typedef size_t size_type; 77 typedef ptrdiff_t difference_type; 78 79 #if __cplusplus <= 201703L 80 // These were removed for C++20, allocator_traits does the right thing. 81 typedef void* pointer; 82 typedef const void* const_pointer; 83 84 template<typename _Tp1> 85 struct rebind 86 { typedef allocator<_Tp1> other; }; 87 #endif 88 89 #if __cplusplus >= 201103L 90 // _GLIBCXX_RESOLVE_LIB_DEFECTS 91 // 2103. std::allocator propagate_on_container_move_assignment 92 using propagate_on_container_move_assignment = true_type; 93 94 using is_always_equal 95 _GLIBCXX20_DEPRECATED_SUGGEST("std::allocator_traits::is_always_equal") 96 = true_type; 97 98 #if __cplusplus >= 202002L 99 // As noted above, these members are present for C++20 to provide the 100 // same API as the primary template, but still trivial as in pre-C++20. 101 allocator() = default; 102 ~allocator() = default; 103 104 template<typename _Up> 105 constexpr 106 allocator(const allocator<_Up>&) noexcept { } 107 108 // No allocate member because it's ill-formed by LWG 3307. 109 // No deallocate member because it would be undefined to call it 110 // with any pointer which wasn't obtained from allocate. 111 #endif // C++20 112 #endif // C++11 113 }; 114 115 /** 116 * @brief The @a standard allocator, as per C++03 [20.4.1]. 117 * 118 * See https://gcc.gnu.org/onlinedocs/libstdc++/manual/memory.html#std.util.memory.allocator 119 * for further details. 120 * 121 * @tparam _Tp Type of allocated object. 122 */ 123 template<typename _Tp> 124 class allocator : public __allocator_base<_Tp> 125 { 126 public: 127 typedef _Tp value_type; 128 typedef size_t size_type; 129 typedef ptrdiff_t difference_type; 130 131 #if __cplusplus <= 201703L 132 // These were removed for C++20. 133 typedef _Tp* pointer; 134 typedef const _Tp* const_pointer; 135 typedef _Tp& reference; 136 typedef const _Tp& const_reference; 137 138 template<typename _Tp1> 139 struct rebind 140 { typedef allocator<_Tp1> other; }; 141 #endif 142 143 #if __cplusplus >= 201103L 144 // _GLIBCXX_RESOLVE_LIB_DEFECTS 145 // 2103. std::allocator propagate_on_container_move_assignment 146 using propagate_on_container_move_assignment = true_type; 147 148 using is_always_equal 149 _GLIBCXX20_DEPRECATED_SUGGEST("std::allocator_traits::is_always_equal") 150 = true_type; 151 #endif 152 153 // _GLIBCXX_RESOLVE_LIB_DEFECTS 154 // 3035. std::allocator's constructors should be constexpr 155 _GLIBCXX20_CONSTEXPR 156 allocator() _GLIBCXX_NOTHROW { } 157 158 _GLIBCXX20_CONSTEXPR 159 allocator(const allocator& __a) _GLIBCXX_NOTHROW 160 : __allocator_base<_Tp>(__a) { } 161 162 #if __cplusplus >= 201103L 163 // Avoid implicit deprecation. 164 allocator& operator=(const allocator&) = default; 165 #endif 166 167 template<typename _Tp1> 168 _GLIBCXX20_CONSTEXPR 169 allocator(const allocator<_Tp1>&) _GLIBCXX_NOTHROW { } 170 171 #if __cpp_constexpr_dynamic_alloc 172 constexpr 173 #endif 174 ~allocator() _GLIBCXX_NOTHROW { } 175 176 #if __cplusplus > 201703L 177 [[nodiscard,__gnu__::__always_inline__]] 178 constexpr _Tp* 179 allocate(size_t __n) 180 { 181 #ifdef __cpp_lib_is_constant_evaluated 182 if (std::is_constant_evaluated()) 183 return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp))); 184 #endif 185 return __allocator_base<_Tp>::allocate(__n, 0); 186 } 187 188 [[__gnu__::__always_inline__]] 189 constexpr void 190 deallocate(_Tp* __p, size_t __n) 191 { 192 #ifdef __cpp_lib_is_constant_evaluated 193 if (std::is_constant_evaluated()) 194 { 195 ::operator delete(__p); 196 return; 197 } 198 #endif 199 __allocator_base<_Tp>::deallocate(__p, __n); 200 } 201 #endif // C++20 202 203 friend _GLIBCXX20_CONSTEXPR bool 204 operator==(const allocator&, const allocator&) _GLIBCXX_NOTHROW 205 { return true; } 206 207 #if __cpp_impl_three_way_comparison < 201907L 208 friend _GLIBCXX20_CONSTEXPR bool 209 operator!=(const allocator&, const allocator&) _GLIBCXX_NOTHROW 210 { return false; } 211 #endif 212 213 // Inherit everything else. 214 }; 215 216 template<typename _T1, typename _T2> 217 inline _GLIBCXX20_CONSTEXPR bool 218 operator==(const allocator<_T1>&, const allocator<_T2>&) 219 _GLIBCXX_NOTHROW 220 { return true; } 221 222 #if __cpp_impl_three_way_comparison < 201907L 223 template<typename _T1, typename _T2> 224 inline _GLIBCXX20_CONSTEXPR bool 225 operator!=(const allocator<_T1>&, const allocator<_T2>&) 226 _GLIBCXX_NOTHROW 227 { return false; } 228 #endif 229 230 // Invalid allocator<cv T> partial specializations. 231 // allocator_traits::rebind_alloc can be used to form a valid allocator type. 232 template<typename _Tp> 233 class allocator<const _Tp> 234 { 235 public: 236 typedef _Tp value_type; 237 template<typename _Up> allocator(const allocator<_Up>&) { } 238 }; 239 240 template<typename _Tp> 241 class allocator<volatile _Tp> 242 { 243 public: 244 typedef _Tp value_type; 245 template<typename _Up> allocator(const allocator<_Up>&) { } 246 }; 247 248 template<typename _Tp> 249 class allocator<const volatile _Tp> 250 { 251 public: 252 typedef _Tp value_type; 253 template<typename _Up> allocator(const allocator<_Up>&) { } 254 }; 255 256 /// @} group allocator 257 258 // Inhibit implicit instantiations for required instantiations, 259 // which are defined via explicit instantiations elsewhere. 260 #if _GLIBCXX_EXTERN_TEMPLATE 261 extern template class allocator<char>; 262 extern template class allocator<wchar_t>; 263 #endif 264 265 // Undefine. 266 #undef __allocator_base 267 268 // To implement Option 3 of DR 431. 269 template<typename _Alloc, bool = __is_empty(_Alloc)> 270 struct __alloc_swap 271 { static void _S_do_it(_Alloc&, _Alloc&) _GLIBCXX_NOEXCEPT { } }; 272 273 template<typename _Alloc> 274 struct __alloc_swap<_Alloc, false> 275 { 276 static void 277 _S_do_it(_Alloc& __one, _Alloc& __two) _GLIBCXX_NOEXCEPT 278 { 279 // Precondition: swappable allocators. 280 if (__one != __two) 281 swap(__one, __two); 282 } 283 }; 284 285 // Optimize for stateless allocators. 286 template<typename _Alloc, bool = __is_empty(_Alloc)> 287 struct __alloc_neq 288 { 289 static bool 290 _S_do_it(const _Alloc&, const _Alloc&) 291 { return false; } 292 }; 293 294 template<typename _Alloc> 295 struct __alloc_neq<_Alloc, false> 296 { 297 static bool 298 _S_do_it(const _Alloc& __one, const _Alloc& __two) 299 { return __one != __two; } 300 }; 301 302 #if __cplusplus >= 201103L 303 template<typename _Tp, bool 304 = __or_<is_copy_constructible<typename _Tp::value_type>, 305 is_nothrow_move_constructible<typename _Tp::value_type>>::value> 306 struct __shrink_to_fit_aux 307 { static bool _S_do_it(_Tp&) noexcept { return false; } }; 308 309 template<typename _Tp> 310 struct __shrink_to_fit_aux<_Tp, true> 311 { 312 static bool 313 _S_do_it(_Tp& __c) noexcept 314 { 315 #if __cpp_exceptions 316 try 317 { 318 _Tp(__make_move_if_noexcept_iterator(__c.begin()), 319 __make_move_if_noexcept_iterator(__c.end()), 320 __c.get_allocator()).swap(__c); 321 return true; 322 } 323 catch(...) 324 { return false; } 325 #else 326 return false; 327 #endif 328 } 329 }; 330 #endif 331 332 _GLIBCXX_END_NAMESPACE_VERSION 333 } // namespace std 334 335 #endif
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