1 // Allocator that wraps operator new -*- C++ -*- 2 3 // Copyright (C) 2001-2020 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 ext/new_allocator.h 26 * This file is a GNU extension to the Standard C++ Library. 27 */ 28 29 #ifndef _NEW_ALLOCATOR_H 30 #define _NEW_ALLOCATOR_H 1 31 32 #include <bits/c++config.h> 33 #include <new> 34 #include <bits/functexcept.h> 35 #include <bits/move.h> 36 #if __cplusplus >= 201103L 37 #include <type_traits> 38 #endif 39 40 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) 41 { 42 _GLIBCXX_BEGIN_NAMESPACE_VERSION 43 44 /** 45 * @brief An allocator that uses global new, as per C++03 [20.4.1]. 46 * @ingroup allocators 47 * 48 * This is precisely the allocator defined in the C++ Standard. 49 * - all allocation calls operator new 50 * - all deallocation calls operator delete 51 * 52 * @tparam _Tp Type of allocated object. 53 */ 54 template<typename _Tp> 55 class new_allocator 56 { 57 public: 58 typedef _Tp value_type; 59 typedef std::size_t size_type; 60 typedef std::ptrdiff_t difference_type; 61 #if __cplusplus <= 201703L 62 typedef _Tp* pointer; 63 typedef const _Tp* const_pointer; 64 typedef _Tp& reference; 65 typedef const _Tp& const_reference; 66 67 template<typename _Tp1> 68 struct rebind 69 { typedef new_allocator<_Tp1> other; }; 70 #endif 71 72 #if __cplusplus >= 201103L 73 // _GLIBCXX_RESOLVE_LIB_DEFECTS 74 // 2103. propagate_on_container_move_assignment 75 typedef std::true_type propagate_on_container_move_assignment; 76 #endif 77 78 _GLIBCXX20_CONSTEXPR 79 new_allocator() _GLIBCXX_USE_NOEXCEPT { } 80 81 _GLIBCXX20_CONSTEXPR 82 new_allocator(const new_allocator&) _GLIBCXX_USE_NOEXCEPT { } 83 84 template<typename _Tp1> 85 _GLIBCXX20_CONSTEXPR 86 new_allocator(const new_allocator<_Tp1>&) _GLIBCXX_USE_NOEXCEPT { } 87 88 #if __cplusplus <= 201703L 89 ~new_allocator() _GLIBCXX_USE_NOEXCEPT { } 90 91 pointer 92 address(reference __x) const _GLIBCXX_NOEXCEPT 93 { return std::__addressof(__x); } 94 95 const_pointer 96 address(const_reference __x) const _GLIBCXX_NOEXCEPT 97 { return std::__addressof(__x); } 98 #endif 99 100 // NB: __n is permitted to be 0. The C++ standard says nothing 101 // about what the return value is when __n == 0. 102 _GLIBCXX_NODISCARD _Tp* 103 allocate(size_type __n, const void* = static_cast<const void*>(0)) 104 { 105 #if __cplusplus >= 201103L 106 // _GLIBCXX_RESOLVE_LIB_DEFECTS 107 // 3308. std::allocator<void>().allocate(n) 108 static_assert(sizeof(_Tp) != 0, "cannot allocate incomplete types"); 109 #endif 110 111 if (__n > this->_M_max_size()) 112 std::__throw_bad_alloc(); 113 114 #if __cpp_aligned_new 115 if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__) 116 { 117 std::align_val_t __al = std::align_val_t(alignof(_Tp)); 118 return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp), __al)); 119 } 120 #endif 121 return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp))); 122 } 123 124 // __p is not permitted to be a null pointer. 125 void 126 deallocate(_Tp* __p, size_type __t) 127 { 128 #if __cpp_aligned_new 129 if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__) 130 { 131 ::operator delete(__p, 132 # if __cpp_sized_deallocation 133 __t * sizeof(_Tp), 134 # endif 135 std::align_val_t(alignof(_Tp))); 136 return; 137 } 138 #endif 139 ::operator delete(__p 140 #if __cpp_sized_deallocation 141 , __t * sizeof(_Tp) 142 #endif 143 ); 144 } 145 146 #if __cplusplus <= 201703L 147 size_type 148 max_size() const _GLIBCXX_USE_NOEXCEPT 149 { return _M_max_size(); } 150 151 #if __cplusplus >= 201103L 152 template<typename _Up, typename... _Args> 153 void 154 construct(_Up* __p, _Args&&... __args) 155 noexcept(std::is_nothrow_constructible<_Up, _Args...>::value) 156 { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); } 157 158 template<typename _Up> 159 void 160 destroy(_Up* __p) 161 noexcept(std::is_nothrow_destructible<_Up>::value) 162 { __p->~_Up(); } 163 #else 164 // _GLIBCXX_RESOLVE_LIB_DEFECTS 165 // 402. wrong new expression in [some_] allocator::construct 166 void 167 construct(pointer __p, const _Tp& __val) 168 { ::new((void *)__p) _Tp(__val); } 169 170 void 171 destroy(pointer __p) { __p->~_Tp(); } 172 #endif 173 #endif // ! C++20 174 175 template<typename _Up> 176 friend _GLIBCXX20_CONSTEXPR bool 177 operator==(const new_allocator&, const new_allocator<_Up>&) 178 _GLIBCXX_NOTHROW 179 { return true; } 180 181 #if __cpp_impl_three_way_comparison < 201907L 182 template<typename _Up> 183 friend _GLIBCXX20_CONSTEXPR bool 184 operator!=(const new_allocator&, const new_allocator<_Up>&) 185 _GLIBCXX_NOTHROW 186 { return false; } 187 #endif 188 189 private: 190 _GLIBCXX_CONSTEXPR size_type 191 _M_max_size() const _GLIBCXX_USE_NOEXCEPT 192 { 193 #if __PTRDIFF_MAX__ < __SIZE_MAX__ 194 return std::size_t(__PTRDIFF_MAX__) / sizeof(_Tp); 195 #else 196 return std::size_t(-1) / sizeof(_Tp); 197 #endif 198 } 199 }; 200 201 _GLIBCXX_END_NAMESPACE_VERSION 202 } // namespace 203 204 #endif 205