libstdc++
new_allocator.h
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1 // Allocator that wraps operator new -*- C++ -*-
2 
3 // Copyright (C) 2001-2017 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  using std::size_t;
45  using std::ptrdiff_t;
46 
47  /**
48  * @brief An allocator that uses global new, as per [20.4].
49  * @ingroup allocators
50  *
51  * This is precisely the allocator defined in the C++ Standard.
52  * - all allocation calls operator new
53  * - all deallocation calls operator delete
54  *
55  * @tparam _Tp Type of allocated object.
56  */
57  template<typename _Tp>
59  {
60  public:
61  typedef size_t size_type;
62  typedef ptrdiff_t difference_type;
63  typedef _Tp* pointer;
64  typedef const _Tp* const_pointer;
65  typedef _Tp& reference;
66  typedef const _Tp& const_reference;
67  typedef _Tp value_type;
68 
69  template<typename _Tp1>
70  struct rebind
71  { typedef new_allocator<_Tp1> other; };
72 
73 #if __cplusplus >= 201103L
74  // _GLIBCXX_RESOLVE_LIB_DEFECTS
75  // 2103. propagate_on_container_move_assignment
77 #endif
78 
79  new_allocator() _GLIBCXX_USE_NOEXCEPT { }
80 
81  new_allocator(const new_allocator&) _GLIBCXX_USE_NOEXCEPT { }
82 
83  template<typename _Tp1>
84  new_allocator(const new_allocator<_Tp1>&) _GLIBCXX_USE_NOEXCEPT { }
85 
86  ~new_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* = static_cast<const void*>(0))
100  {
101  if (__n > this->max_size())
102  std::__throw_bad_alloc();
103 
104 #if __cpp_aligned_new
105  if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
106  {
107  std::align_val_t __al = std::align_val_t(alignof(_Tp));
108  return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp), __al));
109  }
110 #endif
111  return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp)));
112  }
113 
114  // __p is not permitted to be a null pointer.
115  void
116  deallocate(pointer __p, size_type)
117  {
118 #if __cpp_aligned_new
119  if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
120  {
121  ::operator delete(__p, std::align_val_t(alignof(_Tp)));
122  return;
123  }
124 #endif
125  ::operator delete(__p);
126  }
127 
128  size_type
129  max_size() const _GLIBCXX_USE_NOEXCEPT
130  { return size_t(-1) / sizeof(_Tp); }
131 
132 #if __cplusplus >= 201103L
133  template<typename _Up, typename... _Args>
134  void
135  construct(_Up* __p, _Args&&... __args)
136  { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
137 
138  template<typename _Up>
139  void
140  destroy(_Up* __p) { __p->~_Up(); }
141 #else
142  // _GLIBCXX_RESOLVE_LIB_DEFECTS
143  // 402. wrong new expression in [some_] allocator::construct
144  void
145  construct(pointer __p, const _Tp& __val)
146  { ::new((void *)__p) _Tp(__val); }
147 
148  void
149  destroy(pointer __p) { __p->~_Tp(); }
150 #endif
151  };
152 
153  template<typename _Tp>
154  inline bool
155  operator==(const new_allocator<_Tp>&, const new_allocator<_Tp>&)
156  { return true; }
157 
158  template<typename _Tp>
159  inline bool
160  operator!=(const new_allocator<_Tp>&, const new_allocator<_Tp>&)
161  { return false; }
162 
163 _GLIBCXX_END_NAMESPACE_VERSION
164 } // namespace
165 
166 #endif
integral_constant
Definition: type_traits:69
constexpr _Tp * __addressof(_Tp &__r) noexcept
Same as C++11 std::addressof.
Definition: move.h:47
GNU extensions for public use.
An allocator that uses global new, as per [20.4].This is precisely the allocator defined in the C++ S...
Definition: new_allocator.h:58