1 // Allocator that wraps operator new -*- C++ -*- 2 3 // Copyright (C) 2001-2019 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 using std::size_t; 45 using std::ptrdiff_t; 46 47 /** 48 * @brief An allocator that uses global new, as per [20.4]. 49 * @ingroup allocators 50 * 51 * This is precisely the allocator defined in the C++ Standard. 52 * - all allocation calls operator new 53 * - all deallocation calls operator delete 54 * 55 * @tparam _Tp Type of allocated object. 56 */ 57 template<typename _Tp> 58 class new_allocator 59 { 60 public: 61 typedef size_t size_type; 62 typedef ptrdiff_t difference_type; 63 typedef _Tp* pointer; 64 typedef const _Tp* const_pointer; 65 typedef _Tp& reference; 66 typedef const _Tp& const_reference; 67 typedef _Tp value_type; 68 69 template<typename _Tp1> 70 struct rebind 71 { typedef new_allocator<_Tp1> other; }; 72 73 #if __cplusplus >= 201103L 74 // _GLIBCXX_RESOLVE_LIB_DEFECTS 75 // 2103. propagate_on_container_move_assignment 76 typedef std::true_type propagate_on_container_move_assignment; 77 #endif 78 79 _GLIBCXX20_CONSTEXPR 80 new_allocator() _GLIBCXX_USE_NOEXCEPT { } 81 82 _GLIBCXX20_CONSTEXPR 83 new_allocator(const new_allocator&) _GLIBCXX_USE_NOEXCEPT { } 84 85 template<typename _Tp1> 86 _GLIBCXX20_CONSTEXPR 87 new_allocator(const new_allocator<_Tp1>&) _GLIBCXX_USE_NOEXCEPT { } 88 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 99 // NB: __n is permitted to be 0. The C++ standard says nothing 100 // about what the return value is when __n == 0. 101 _GLIBCXX_NODISCARD pointer 102 allocate(size_type __n, const void* = static_cast<const void*>(0)) 103 { 104 if (__n > this->max_size()) 105 std::__throw_bad_alloc(); 106 107 #if __cpp_aligned_new 108 if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__) 109 { 110 std::align_val_t __al = std::align_val_t(alignof(_Tp)); 111 return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp), __al)); 112 } 113 #endif 114 return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp))); 115 } 116 117 // __p is not permitted to be a null pointer. 118 void 119 deallocate(pointer __p, size_type) 120 { 121 #if __cpp_aligned_new 122 if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__) 123 { 124 ::operator delete(__p, std::align_val_t(alignof(_Tp))); 125 return; 126 } 127 #endif 128 ::operator delete(__p); 129 } 130 131 size_type 132 max_size() const _GLIBCXX_USE_NOEXCEPT 133 { 134 #if __PTRDIFF_MAX__ < __SIZE_MAX__ 135 return size_t(__PTRDIFF_MAX__) / sizeof(_Tp); 136 #else 137 return size_t(-1) / sizeof(_Tp); 138 #endif 139 } 140 141 #if __cplusplus >= 201103L 142 template<typename _Up, typename... _Args> 143 void 144 construct(_Up* __p, _Args&&... __args) 145 noexcept(noexcept(::new((void *)__p) 146 _Up(std::forward<_Args>(__args)...))) 147 { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); } 148 149 template<typename _Up> 150 void 151 destroy(_Up* __p) 152 noexcept(noexcept( __p->~_Up())) 153 { __p->~_Up(); } 154 #else 155 // _GLIBCXX_RESOLVE_LIB_DEFECTS 156 // 402. wrong new expression in [some_] allocator::construct 157 void 158 construct(pointer __p, const _Tp& __val) 159 { ::new((void *)__p) _Tp(__val); } 160 161 void 162 destroy(pointer __p) { __p->~_Tp(); } 163 #endif 164 165 template<typename _Up> 166 friend bool 167 operator==(const new_allocator&, const new_allocator<_Up>&) 168 _GLIBCXX_NOTHROW 169 { return true; } 170 171 template<typename _Up> 172 friend bool 173 operator!=(const new_allocator&, const new_allocator<_Up>&) 174 _GLIBCXX_NOTHROW 175 { return false; } 176 }; 177 178 _GLIBCXX_END_NAMESPACE_VERSION 179 } // namespace 180 181 #endif 182