1 | // Allocator that wraps operator new -*- 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 | /** @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 (__builtin_expect(__n > this->_M_max_size(), false)) |
112 | { |
113 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
114 | // 3190. allocator::allocate sometimes returns too little storage |
115 | if (__n > (std::size_t(-1) / sizeof(_Tp))) |
116 | std::__throw_bad_array_new_length(); |
117 | std::__throw_bad_alloc(); |
118 | } |
119 | |
120 | #if __cpp_aligned_new |
121 | if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__) |
122 | { |
123 | std::align_val_t __al = std::align_val_t(alignof(_Tp)); |
124 | return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp), __al)); |
125 | } |
126 | #endif |
127 | return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp))); |
128 | } |
129 | |
130 | // __p is not permitted to be a null pointer. |
131 | void |
132 | deallocate(_Tp* __p, size_type __t __attribute__ ((__unused__))) |
133 | { |
134 | #if __cpp_aligned_new |
135 | if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__) |
136 | { |
137 | ::operator delete(__p, |
138 | # if __cpp_sized_deallocation |
139 | __t * sizeof(_Tp), |
140 | # endif |
141 | std::align_val_t(alignof(_Tp))); |
142 | return; |
143 | } |
144 | #endif |
145 | ::operator delete(__p |
146 | #if __cpp_sized_deallocation |
147 | , __t * sizeof(_Tp) |
148 | #endif |
149 | ); |
150 | } |
151 | |
152 | #if __cplusplus <= 201703L |
153 | size_type |
154 | max_size() const _GLIBCXX_USE_NOEXCEPT |
155 | { return _M_max_size(); } |
156 | |
157 | #if __cplusplus >= 201103L |
158 | template<typename _Up, typename... _Args> |
159 | void |
160 | construct(_Up* __p, _Args&&... __args) |
161 | noexcept(std::is_nothrow_constructible<_Up, _Args...>::value) |
162 | { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); } |
163 | |
164 | template<typename _Up> |
165 | void |
166 | destroy(_Up* __p) |
167 | noexcept(std::is_nothrow_destructible<_Up>::value) |
168 | { __p->~_Up(); } |
169 | #else |
170 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
171 | // 402. wrong new expression in [some_] allocator::construct |
172 | void |
173 | construct(pointer __p, const _Tp& __val) |
174 | { ::new((void *)__p) _Tp(__val); } |
175 | |
176 | void |
177 | destroy(pointer __p) { __p->~_Tp(); } |
178 | #endif |
179 | #endif // ! C++20 |
180 | |
181 | template<typename _Up> |
182 | friend _GLIBCXX20_CONSTEXPR bool |
183 | operator==(const new_allocator&, const new_allocator<_Up>&) |
184 | _GLIBCXX_NOTHROW |
185 | { return true; } |
186 | |
187 | #if __cpp_impl_three_way_comparison < 201907L |
188 | template<typename _Up> |
189 | friend _GLIBCXX20_CONSTEXPR bool |
190 | operator!=(const new_allocator&, const new_allocator<_Up>&) |
191 | _GLIBCXX_NOTHROW |
192 | { return false; } |
193 | #endif |
194 | |
195 | private: |
196 | _GLIBCXX_CONSTEXPR size_type |
197 | _M_max_size() const _GLIBCXX_USE_NOEXCEPT |
198 | { |
199 | #if __PTRDIFF_MAX__ < __SIZE_MAX__ |
200 | return std::size_t(__PTRDIFF_MAX__) / sizeof(_Tp); |
201 | #else |
202 | return std::size_t(-1) / sizeof(_Tp); |
203 | #endif |
204 | } |
205 | }; |
206 | |
207 | _GLIBCXX_END_NAMESPACE_VERSION |
208 | } // namespace |
209 | |
210 | #endif |
211 | |