libstdc++
new_allocator.h
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1 // Allocator that wraps operator new -*- C++ -*-
2 
3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2009
4 // Free Software Foundation, Inc.
5 //
6 // This file is part of the GNU ISO C++ Library. This library is free
7 // software; you can redistribute it and/or modify it under the
8 // terms of the GNU General Public License as published by the
9 // Free Software Foundation; either version 3, or (at your option)
10 // any later version.
11 
12 // This library is distributed in the hope that it will be useful,
13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 // GNU General Public License for more details.
16 
17 // Under Section 7 of GPL version 3, you are granted additional
18 // permissions described in the GCC Runtime Library Exception, version
19 // 3.1, as published by the Free Software Foundation.
20 
21 // You should have received a copy of the GNU General Public License and
22 // a copy of the GCC Runtime Library Exception along with this program;
23 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
24 // <http://www.gnu.org/licenses/>.
25 
26 /** @file ext/new_allocator.h
27  * This file is a GNU extension to the Standard C++ Library.
28  */
29 
30 #ifndef _NEW_ALLOCATOR_H
31 #define _NEW_ALLOCATOR_H 1
32 
33 #include <new>
34 #include <bits/functexcept.h>
35 #include <bits/move.h>
36 
37 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
38 
39  using std::size_t;
40  using std::ptrdiff_t;
41 
42  /**
43  * @brief An allocator that uses global new, as per [20.4].
44  * @ingroup allocators
45  *
46  * This is precisely the allocator defined in the C++ Standard.
47  * - all allocation calls operator new
48  * - all deallocation calls operator delete
49  */
50  template<typename _Tp>
52  {
53  public:
54  typedef size_t size_type;
55  typedef ptrdiff_t difference_type;
56  typedef _Tp* pointer;
57  typedef const _Tp* const_pointer;
58  typedef _Tp& reference;
59  typedef const _Tp& const_reference;
60  typedef _Tp value_type;
61 
62  template<typename _Tp1>
63  struct rebind
64  { typedef new_allocator<_Tp1> other; };
65 
66  new_allocator() throw() { }
67 
68  new_allocator(const new_allocator&) throw() { }
69 
70  template<typename _Tp1>
71  new_allocator(const new_allocator<_Tp1>&) throw() { }
72 
73  ~new_allocator() throw() { }
74 
75  pointer
76  address(reference __x) const { return &__x; }
77 
78  const_pointer
79  address(const_reference __x) const { return &__x; }
80 
81  // NB: __n is permitted to be 0. The C++ standard says nothing
82  // about what the return value is when __n == 0.
83  pointer
84  allocate(size_type __n, const void* = 0)
85  {
86  if (__builtin_expect(__n > this->max_size(), false))
87  std::__throw_bad_alloc();
88 
89  return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp)));
90  }
91 
92  // __p is not permitted to be a null pointer.
93  void
94  deallocate(pointer __p, size_type)
95  { ::operator delete(__p); }
96 
97  size_type
98  max_size() const throw()
99  { return size_t(-1) / sizeof(_Tp); }
100 
101  // _GLIBCXX_RESOLVE_LIB_DEFECTS
102  // 402. wrong new expression in [some_] allocator::construct
103  void
104  construct(pointer __p, const _Tp& __val)
105  { ::new((void *)__p) _Tp(__val); }
106 
107 #ifdef __GXX_EXPERIMENTAL_CXX0X__
108  template<typename... _Args>
109  void
110  construct(pointer __p, _Args&&... __args)
111  { ::new((void *)__p) _Tp(std::forward<_Args>(__args)...); }
112 #endif
113 
114  void
115  destroy(pointer __p) { __p->~_Tp(); }
116  };
117 
118  template<typename _Tp>
119  inline bool
120  operator==(const new_allocator<_Tp>&, const new_allocator<_Tp>&)
121  { return true; }
122 
123  template<typename _Tp>
124  inline bool
125  operator!=(const new_allocator<_Tp>&, const new_allocator<_Tp>&)
126  { return false; }
127 
128 _GLIBCXX_END_NAMESPACE
129 
130 #endif