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The C and C++ Include Header Files
/usr/include/c++/13/bits/new_allocator.h
$ cat -n /usr/include/c++/13/bits/new_allocator.h 1 // Allocator that wraps operator new -*- C++ -*- 2 3 // Copyright (C) 2001-2023 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/new_allocator.h 26 * This is an internal header file, included by other library headers. 27 * Do not attempt to use it directly. @headername{memory} 28 */ 29 30 #ifndef _STD_NEW_ALLOCATOR_H 31 #define _STD_NEW_ALLOCATOR_H 1 32 33 #include <bits/c++config.h> 34 #include <new> 35 #include <bits/functexcept.h> 36 #include <bits/move.h> 37 #if __cplusplus >= 201103L 38 #include <type_traits> 39 #endif 40 41 namespace std _GLIBCXX_VISIBILITY(default) 42 { 43 _GLIBCXX_BEGIN_NAMESPACE_VERSION 44 45 /** 46 * @brief An allocator that uses global `new`, as per C++03 [20.4.1]. 47 * @ingroup allocators 48 * 49 * This is precisely the allocator defined in the C++ Standard. 50 * - all allocation calls `operator new` 51 * - all deallocation calls `operator delete` 52 * 53 * This is the default base-class implementation of `std::allocator`, 54 * and is also the base-class of the `__gnu_cxx::new_allocator` extension. 55 * You should use either `std::allocator` or `__gnu_cxx::new_allocator` 56 * instead of using this directly. 57 * 58 * @tparam _Tp Type of allocated object. 59 * 60 * @headerfile memory 61 */ 62 template<typename _Tp> 63 class __new_allocator 64 { 65 public: 66 typedef _Tp value_type; 67 typedef std::size_t size_type; 68 typedef std::ptrdiff_t difference_type; 69 #if __cplusplus <= 201703L 70 typedef _Tp* pointer; 71 typedef const _Tp* const_pointer; 72 typedef _Tp& reference; 73 typedef const _Tp& const_reference; 74 75 template<typename _Tp1> 76 struct rebind 77 { typedef __new_allocator<_Tp1> other; }; 78 #endif 79 80 #if __cplusplus >= 201103L 81 // _GLIBCXX_RESOLVE_LIB_DEFECTS 82 // 2103. propagate_on_container_move_assignment 83 typedef std::true_type propagate_on_container_move_assignment; 84 #endif 85 86 __attribute__((__always_inline__)) 87 _GLIBCXX20_CONSTEXPR 88 __new_allocator() _GLIBCXX_USE_NOEXCEPT { } 89 90 __attribute__((__always_inline__)) 91 _GLIBCXX20_CONSTEXPR 92 __new_allocator(const __new_allocator&) _GLIBCXX_USE_NOEXCEPT { } 93 94 template<typename _Tp1> 95 __attribute__((__always_inline__)) 96 _GLIBCXX20_CONSTEXPR 97 __new_allocator(const __new_allocator<_Tp1>&) _GLIBCXX_USE_NOEXCEPT { } 98 99 #if __cplusplus >= 201103L 100 __new_allocator& operator=(const __new_allocator&) = default; 101 #endif 102 103 #if __cplusplus <= 201703L 104 ~__new_allocator() _GLIBCXX_USE_NOEXCEPT { } 105 106 pointer 107 address(reference __x) const _GLIBCXX_NOEXCEPT 108 { return std::__addressof(__x); } 109 110 const_pointer 111 address(const_reference __x) const _GLIBCXX_NOEXCEPT 112 { return std::__addressof(__x); } 113 #endif 114 115 #if __has_builtin(__builtin_operator_new) >= 201802L 116 # define _GLIBCXX_OPERATOR_NEW __builtin_operator_new 117 # define _GLIBCXX_OPERATOR_DELETE __builtin_operator_delete 118 #else 119 # define _GLIBCXX_OPERATOR_NEW ::operator new 120 # define _GLIBCXX_OPERATOR_DELETE ::operator delete 121 #endif 122 123 // NB: __n is permitted to be 0. The C++ standard says nothing 124 // about what the return value is when __n == 0. 125 _GLIBCXX_NODISCARD _Tp* 126 allocate(size_type __n, const void* = static_cast<const void*>(0)) 127 { 128 #if __cplusplus >= 201103L 129 // _GLIBCXX_RESOLVE_LIB_DEFECTS 130 // 3308. std::allocator<void>().allocate(n) 131 static_assert(sizeof(_Tp) != 0, "cannot allocate incomplete types"); 132 #endif 133 134 if (__builtin_expect(__n > this->_M_max_size(), false)) 135 { 136 // _GLIBCXX_RESOLVE_LIB_DEFECTS 137 // 3190. allocator::allocate sometimes returns too little storage 138 if (__n > (std::size_t(-1) / sizeof(_Tp))) 139 std::__throw_bad_array_new_length(); 140 std::__throw_bad_alloc(); 141 } 142 143 #if __cpp_aligned_new 144 if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__) 145 { 146 std::align_val_t __al = std::align_val_t(alignof(_Tp)); 147 return static_cast<_Tp*>(_GLIBCXX_OPERATOR_NEW(__n * sizeof(_Tp), 148 __al)); 149 } 150 #endif 151 return static_cast<_Tp*>(_GLIBCXX_OPERATOR_NEW(__n * sizeof(_Tp))); 152 } 153 154 // __p is not permitted to be a null pointer. 155 void 156 deallocate(_Tp* __p, size_type __n __attribute__ ((__unused__))) 157 { 158 #if __cpp_sized_deallocation 159 # define _GLIBCXX_SIZED_DEALLOC(p, n) (p), (n) * sizeof(_Tp) 160 #else 161 # define _GLIBCXX_SIZED_DEALLOC(p, n) (p) 162 #endif 163 164 #if __cpp_aligned_new 165 if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__) 166 { 167 _GLIBCXX_OPERATOR_DELETE(_GLIBCXX_SIZED_DEALLOC(__p, __n), 168 std::align_val_t(alignof(_Tp))); 169 return; 170 } 171 #endif 172 _GLIBCXX_OPERATOR_DELETE(_GLIBCXX_SIZED_DEALLOC(__p, __n)); 173 } 174 175 #undef _GLIBCXX_SIZED_DEALLOC 176 #undef _GLIBCXX_OPERATOR_DELETE 177 #undef _GLIBCXX_OPERATOR_NEW 178 179 #if __cplusplus <= 201703L 180 __attribute__((__always_inline__)) 181 size_type 182 max_size() const _GLIBCXX_USE_NOEXCEPT 183 { return _M_max_size(); } 184 185 #if __cplusplus >= 201103L 186 template<typename _Up, typename... _Args> 187 __attribute__((__always_inline__)) 188 void 189 construct(_Up* __p, _Args&&... __args) 190 noexcept(std::is_nothrow_constructible<_Up, _Args...>::value) 191 { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); } 192 193 template<typename _Up> 194 __attribute__((__always_inline__)) 195 void 196 destroy(_Up* __p) 197 noexcept(std::is_nothrow_destructible<_Up>::value) 198 { __p->~_Up(); } 199 #else 200 // _GLIBCXX_RESOLVE_LIB_DEFECTS 201 // 402. wrong new expression in [some_] allocator::construct 202 __attribute__((__always_inline__)) 203 void 204 construct(pointer __p, const _Tp& __val) 205 { ::new((void *)__p) _Tp(__val); } 206 207 __attribute__((__always_inline__)) 208 void 209 destroy(pointer __p) { __p->~_Tp(); } 210 #endif 211 #endif // ! C++20 212 213 template<typename _Up> 214 friend __attribute__((__always_inline__)) _GLIBCXX20_CONSTEXPR bool 215 operator==(const __new_allocator&, const __new_allocator<_Up>&) 216 _GLIBCXX_NOTHROW 217 { return true; } 218 219 #if __cpp_impl_three_way_comparison < 201907L 220 template<typename _Up> 221 friend __attribute__((__always_inline__)) _GLIBCXX20_CONSTEXPR bool 222 operator!=(const __new_allocator&, const __new_allocator<_Up>&) 223 _GLIBCXX_NOTHROW 224 { return false; } 225 #endif 226 227 private: 228 __attribute__((__always_inline__)) 229 _GLIBCXX_CONSTEXPR size_type 230 _M_max_size() const _GLIBCXX_USE_NOEXCEPT 231 { 232 #if __PTRDIFF_MAX__ < __SIZE_MAX__ 233 return std::size_t(__PTRDIFF_MAX__) / sizeof(_Tp); 234 #else 235 return std::size_t(-1) / sizeof(_Tp); 236 #endif 237 } 238 }; 239 240 _GLIBCXX_END_NAMESPACE_VERSION 241 } // namespace 242 243 #endif
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