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1 : // Allocator that wraps operator new -*- C++ -*-
2 :
3 : // Copyright (C) 2001-2024 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 90 : __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 90 : ~__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 && __cplusplus >= 201103L
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 0 : 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 && __cplusplus >= 201103L
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 0 : _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(__is_nothrow_new_constructible<_Up, _Args...>)
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 0 : { __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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