libstdc++
malloc_allocator.h
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1 // Allocator that wraps "C" malloc -*- C++ -*-
2 
3 // Copyright (C) 2001-2018 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 
41 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
42 {
43 _GLIBCXX_BEGIN_NAMESPACE_VERSION
44 
45  using std::size_t;
46  using std::ptrdiff_t;
47 
48  /**
49  * @brief An allocator that uses malloc.
50  * @ingroup allocators
51  *
52  * This is precisely the allocator defined in the C++ Standard.
53  * - all allocation calls malloc
54  * - all deallocation calls free
55  */
56  template<typename _Tp>
58  {
59  public:
60  typedef size_t size_type;
61  typedef ptrdiff_t difference_type;
62  typedef _Tp* pointer;
63  typedef const _Tp* const_pointer;
64  typedef _Tp& reference;
65  typedef const _Tp& const_reference;
66  typedef _Tp value_type;
67 
68  template<typename _Tp1>
69  struct rebind
70  { typedef malloc_allocator<_Tp1> other; };
71 
72 #if __cplusplus >= 201103L
73  // _GLIBCXX_RESOLVE_LIB_DEFECTS
74  // 2103. propagate_on_container_move_assignment
76 #endif
77 
78  malloc_allocator() _GLIBCXX_USE_NOEXCEPT { }
79 
80  malloc_allocator(const malloc_allocator&) _GLIBCXX_USE_NOEXCEPT { }
81 
82  template<typename _Tp1>
84  _GLIBCXX_USE_NOEXCEPT { }
85 
86  ~malloc_allocator() _GLIBCXX_USE_NOEXCEPT { }
87 
88  pointer
89  address(reference __x) const _GLIBCXX_NOEXCEPT
90  { return std::__addressof(__x); }
91 
92  const_pointer
93  address(const_reference __x) const _GLIBCXX_NOEXCEPT
94  { return std::__addressof(__x); }
95 
96  // NB: __n is permitted to be 0. The C++ standard says nothing
97  // about what the return value is when __n == 0.
98  pointer
99  allocate(size_type __n, const void* = 0)
100  {
101  if (__n > this->max_size())
102  std::__throw_bad_alloc();
103 
104  pointer __ret = 0;
105 #if __cpp_aligned_new
106 #if __cplusplus > 201402L && _GLIBCXX_HAVE_ALIGNED_ALLOC
107  if (alignof(_Tp) > alignof(std::max_align_t))
108  {
109  __ret = static_cast<_Tp*>(::aligned_alloc(alignof(_Tp),
110  __n * sizeof(_Tp)));
111  }
112 #else
113 # define _GLIBCXX_CHECK_MALLOC_RESULT
114 #endif
115 #endif
116  if (!__ret)
117  __ret = static_cast<_Tp*>(std::malloc(__n * sizeof(_Tp)));
118  if (!__ret)
119  std::__throw_bad_alloc();
120 #ifdef _GLIBCXX_CHECK_MALLOC_RESULT
121 #undef _GLIBCXX_CHECK_MALLOC_RESULT
122  if (reinterpret_cast<std::size_t>(__ret) % alignof(_Tp))
123  {
124  // Memory returned by malloc is not suitably aligned for _Tp.
125  deallocate(__ret, __n);
126  std::__throw_bad_alloc();
127  }
128 #endif
129  return __ret;
130  }
131 
132  // __p is not permitted to be a null pointer.
133  void
134  deallocate(pointer __p, size_type)
135  { std::free(static_cast<void*>(__p)); }
136 
137  size_type
138  max_size() const _GLIBCXX_USE_NOEXCEPT
139  { return size_t(-1) / sizeof(_Tp); }
140 
141 #if __cplusplus >= 201103L
142  template<typename _Up, typename... _Args>
143  void
144  construct(_Up* __p, _Args&&... __args)
145  { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
146 
147  template<typename _Up>
148  void
149  destroy(_Up* __p) { __p->~_Up(); }
150 #else
151  // _GLIBCXX_RESOLVE_LIB_DEFECTS
152  // 402. wrong new expression in [some_] allocator::construct
153  void
154  construct(pointer __p, const _Tp& __val)
155  { ::new((void *)__p) value_type(__val); }
156 
157  void
158  destroy(pointer __p) { __p->~_Tp(); }
159 #endif
160  };
161 
162  template<typename _Tp>
163  inline bool
164  operator==(const malloc_allocator<_Tp>&, const malloc_allocator<_Tp>&)
165  { return true; }
166 
167  template<typename _Tp>
168  inline bool
169  operator!=(const malloc_allocator<_Tp>&, const malloc_allocator<_Tp>&)
170  { return false; }
171 
172 _GLIBCXX_END_NAMESPACE_VERSION
173 } // namespace
174 
175 #endif
constexpr _Tp * __addressof(_Tp &__r) noexcept
Same as C++11 std::addressof.
Definition: move.h:47
GNU extensions for public use.
integral_constant
Definition: type_traits:57
An allocator that uses malloc.This is precisely the allocator defined in the C++ Standard.