libstdc++
new_allocator.h
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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
40namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
41{
42_GLIBCXX_BEGIN_NAMESPACE_VERSION
43
44 /**
45 * @brief An allocator that uses global new, as per [20.4].
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>
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
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 (__n > this->_M_max_size())
106 std::__throw_bad_alloc();
107
108#if __cpp_aligned_new
109 if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
110 {
111 std::align_val_t __al = std::align_val_t(alignof(_Tp));
112 return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp), __al));
113 }
114#endif
115 return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp)));
116 }
117
118 // __p is not permitted to be a null pointer.
119 void
120 deallocate(_Tp* __p, size_type __t)
121 {
122#if __cpp_aligned_new
123 if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
124 {
125 ::operator delete(__p,
126# if __cpp_sized_deallocation
127 __t * sizeof(_Tp),
128# endif
129 std::align_val_t(alignof(_Tp)));
130 return;
131 }
132#endif
133 ::operator delete(__p
134#if __cpp_sized_deallocation
135 , __t * sizeof(_Tp)
136#endif
137 );
138 }
139
140#if __cplusplus <= 201703L
141 size_type
142 max_size() const _GLIBCXX_USE_NOEXCEPT
143 { return _M_max_size(); }
144
145#if __cplusplus >= 201103L
146 template<typename _Up, typename... _Args>
147 void
148 construct(_Up* __p, _Args&&... __args)
149 noexcept(noexcept(::new((void *)__p)
150 _Up(std::forward<_Args>(__args)...)))
151 { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
152
153 template<typename _Up>
154 void
155 destroy(_Up* __p)
156 noexcept(noexcept( __p->~_Up()))
157 { __p->~_Up(); }
158#else
159 // _GLIBCXX_RESOLVE_LIB_DEFECTS
160 // 402. wrong new expression in [some_] allocator::construct
161 void
162 construct(pointer __p, const _Tp& __val)
163 { ::new((void *)__p) _Tp(__val); }
164
165 void
166 destroy(pointer __p) { __p->~_Tp(); }
167#endif
168#endif // ! C++20
169
170 template<typename _Up>
171 friend _GLIBCXX20_CONSTEXPR bool
172 operator==(const new_allocator&, const new_allocator<_Up>&)
173 _GLIBCXX_NOTHROW
174 { return true; }
175
176 template<typename _Up>
177 friend _GLIBCXX20_CONSTEXPR bool
178 operator!=(const new_allocator&, const new_allocator<_Up>&)
179 _GLIBCXX_NOTHROW
180 { return false; }
181
182 private:
183 _GLIBCXX_CONSTEXPR size_type
184 _M_max_size() const _GLIBCXX_USE_NOEXCEPT
185 {
186#if __PTRDIFF_MAX__ < __SIZE_MAX__
187 return std::size_t(__PTRDIFF_MAX__) / sizeof(_Tp);
188#else
189 return std::size_t(-1) / sizeof(_Tp);
190#endif
191 }
192 };
193
194_GLIBCXX_END_NAMESPACE_VERSION
195} // namespace
196
197#endif
constexpr _Tp * __addressof(_Tp &__r) noexcept
Same as C++11 std::addressof.
Definition: move.h:49
GNU extensions for public use.
integral_constant
Definition: type_traits:58
An allocator that uses global new, as per [20.4].
Definition: new_allocator.h:56