libstdc++
malloc_allocator.h
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1// Allocator that wraps "C" malloc -*- 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/malloc_allocator.h
26 * This file is a GNU extension to the Standard C++ Library.
27 */
28
29#ifndef _MALLOC_ALLOCATOR_H
30#define _MALLOC_ALLOCATOR_H 1
31
32#include <cstdlib>
33#include <cstddef>
34#include <new>
35#include <bits/functexcept.h>
36#include <bits/move.h>
37#if __cplusplus >= 201103L
38#include <type_traits>
39#endif
40
41namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
42{
43_GLIBCXX_BEGIN_NAMESPACE_VERSION
44
45 /**
46 * @brief An allocator that uses malloc.
47 * @ingroup allocators
48 *
49 * This is precisely the allocator defined in the C++ Standard.
50 * - all allocation calls malloc
51 * - all deallocation calls free
52 */
53 template<typename _Tp>
55 {
56 public:
57 typedef _Tp value_type;
58 typedef std::size_t size_type;
59 typedef std::ptrdiff_t difference_type;
60#if __cplusplus <= 201703L
61 typedef _Tp* pointer;
62 typedef const _Tp* const_pointer;
63 typedef _Tp& reference;
64 typedef const _Tp& const_reference;
65
66 template<typename _Tp1>
67 struct rebind
68 { typedef malloc_allocator<_Tp1> other; };
69#endif
70
71#if __cplusplus >= 201103L
72 // _GLIBCXX_RESOLVE_LIB_DEFECTS
73 // 2103. propagate_on_container_move_assignment
75#endif
76
77 _GLIBCXX20_CONSTEXPR
78 malloc_allocator() _GLIBCXX_USE_NOEXCEPT { }
79
80 _GLIBCXX20_CONSTEXPR
81 malloc_allocator(const malloc_allocator&) _GLIBCXX_USE_NOEXCEPT { }
82
83 template<typename _Tp1>
84 _GLIBCXX20_CONSTEXPR
86 _GLIBCXX_USE_NOEXCEPT { }
87
88#if __cplusplus <= 201703L
89 ~malloc_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 _Tp*
103 allocate(size_type __n, const void* = 0)
104 {
105 if (__n > this->_M_max_size())
106 std::__throw_bad_alloc();
107
108 _Tp* __ret = 0;
109#if __cpp_aligned_new
110#if __cplusplus > 201402L && _GLIBCXX_HAVE_ALIGNED_ALLOC
111 if (alignof(_Tp) > alignof(std::max_align_t))
112 {
113 __ret = static_cast<_Tp*>(::aligned_alloc(alignof(_Tp),
114 __n * sizeof(_Tp)));
115 }
116#else
117# define _GLIBCXX_CHECK_MALLOC_RESULT
118#endif
119#endif
120 if (!__ret)
121 __ret = static_cast<_Tp*>(std::malloc(__n * sizeof(_Tp)));
122 if (!__ret)
123 std::__throw_bad_alloc();
124#ifdef _GLIBCXX_CHECK_MALLOC_RESULT
125#undef _GLIBCXX_CHECK_MALLOC_RESULT
126 if (reinterpret_cast<std::size_t>(__ret) % alignof(_Tp))
127 {
128 // Memory returned by malloc is not suitably aligned for _Tp.
129 deallocate(__ret, __n);
130 std::__throw_bad_alloc();
131 }
132#endif
133 return __ret;
134 }
135
136 // __p is not permitted to be a null pointer.
137 void
138 deallocate(_Tp* __p, size_type)
139 { std::free(static_cast<void*>(__p)); }
140
141#if __cplusplus <= 201703L
142 size_type
143 max_size() const _GLIBCXX_USE_NOEXCEPT
144 { return _M_max_size(); }
145
146#if __cplusplus >= 201103L
147 template<typename _Up, typename... _Args>
148 void
149 construct(_Up* __p, _Args&&... __args)
150 noexcept(noexcept(::new((void *)__p)
151 _Up(std::forward<_Args>(__args)...)))
152 { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
153
154 template<typename _Up>
155 void
156 destroy(_Up* __p)
157 noexcept(noexcept(__p->~_Up()))
158 { __p->~_Up(); }
159#else
160 // _GLIBCXX_RESOLVE_LIB_DEFECTS
161 // 402. wrong new expression in [some_] allocator::construct
162 void
163 construct(pointer __p, const _Tp& __val)
164 { ::new((void *)__p) value_type(__val); }
165
166 void
167 destroy(pointer __p) { __p->~_Tp(); }
168#endif
169#endif // ! C++20
170
171 template<typename _Up>
172 friend _GLIBCXX20_CONSTEXPR bool
173 operator==(const malloc_allocator&, const malloc_allocator<_Up>&)
174 _GLIBCXX_NOTHROW
175 { return true; }
176
177 template<typename _Up>
178 friend _GLIBCXX20_CONSTEXPR bool
179 operator!=(const malloc_allocator&, const malloc_allocator<_Up>&)
180 _GLIBCXX_NOTHROW
181 { return false; }
182
183 private:
184 _GLIBCXX_CONSTEXPR size_type
185 _M_max_size() const _GLIBCXX_USE_NOEXCEPT
186 {
187#if __PTRDIFF_MAX__ < __SIZE_MAX__
188 return std::size_t(__PTRDIFF_MAX__) / sizeof(_Tp);
189#else
190 return std::size_t(-1) / sizeof(_Tp);
191#endif
192 }
193 };
194
195_GLIBCXX_END_NAMESPACE_VERSION
196} // namespace
197
198#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 malloc.