libstdc++
extptr_allocator.h
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1 // <extptr_allocator.h> -*- C++ -*-
2 
3 // Copyright (C) 2008, 2009 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 /**
26  * @file ext/extptr_allocator.h
27  * @author Bob Walters
28  *
29  * An example allocator which uses an alternative pointer type from
30  * bits/pointer.h. Supports test cases which confirm container support
31  * for alternative pointers.
32  */
33 
34 #ifndef _EXTPTR_ALLOCATOR_H
35 #define _EXTPTR_ALLOCATOR_H 1
36 
37 #include <memory>
38 #include <limits>
39 #include <ext/pointer.h>
40 
41 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
42 
43  /**
44  * @brief An example allocator which uses a non-standard pointer type.
45  * @ingroup allocators
46  *
47  * This allocator specifies that containers use a 'relative pointer' as it's
48  * pointer type. (See ext/pointer.h) Memory allocation in this example
49  * is still performed using std::allocator.
50  */
51  template<typename _Tp>
53  {
54  public:
55  typedef std::size_t size_type;
56  typedef std::ptrdiff_t difference_type;
57 
58  // Note the non-standard pointer types.
62 
63  typedef _Tp& reference;
64  typedef const _Tp& const_reference;
65  typedef _Tp value_type;
66 
67  template<typename _Up>
68  struct rebind
69  { typedef _ExtPtr_allocator<_Up> other; };
70 
71  _ExtPtr_allocator() throw()
72  : _M_real_alloc() { }
73 
74  _ExtPtr_allocator(const _ExtPtr_allocator &__rarg) throw()
75  : _M_real_alloc(__rarg._M_real_alloc) { }
76 
77  template<typename _Up>
78  _ExtPtr_allocator(const _ExtPtr_allocator<_Up>& __rarg) throw()
79  : _M_real_alloc(__rarg._M_getUnderlyingImp()) { }
80 
81  ~_ExtPtr_allocator() throw()
82  { }
83 
84  pointer address(reference __x) const
85  { return &__x; }
86 
87  const_pointer address(const_reference __x) const
88  { return &__x; }
89 
90  pointer allocate(size_type __n, void* __hint = 0)
91  { return _M_real_alloc.allocate(__n,__hint); }
92 
93  void deallocate(pointer __p, size_type __n)
94  { _M_real_alloc.deallocate(__p.get(), __n); }
95 
96  size_type max_size() const throw()
97  { return std::numeric_limits<size_type>::max() / sizeof(_Tp); }
98 
99  void construct(pointer __p, const _Tp& __val)
100  { ::new(__p.get()) _Tp(__val); }
101 
102 #ifdef __GXX_EXPERIMENTAL_CXX0X__
103  template<typename... _Args>
104  void
105  construct(pointer __p, _Args&&... __args)
106  { ::new(__p.get()) _Tp(std::forward<_Args>(__args)...); }
107 #endif
108 
109  void destroy(pointer __p)
110  { __p->~_Tp(); }
111 
112  template<typename _Up>
113  inline bool
114  operator==(const _ExtPtr_allocator<_Up>& __rarg)
115  { return _M_real_alloc == __rarg._M_getUnderlyingImp(); }
116 
117  inline bool
118  operator==(const _ExtPtr_allocator& __rarg)
119  { return _M_real_alloc == __rarg._M_real_alloc; }
120 
121  template<typename _Up>
122  inline bool
123  operator!=(const _ExtPtr_allocator<_Up>& __rarg)
124  { return _M_real_alloc != __rarg._M_getUnderlyingImp(); }
125 
126  inline bool
127  operator!=(const _ExtPtr_allocator& __rarg)
128  { return _M_real_alloc != __rarg._M_real_alloc; }
129 
130  template<typename _Up>
131  inline friend void
133 
134  // A method specific to this implementation.
135  const std::allocator<_Tp>&
136  _M_getUnderlyingImp() const
137  { return _M_real_alloc; }
138 
139  private:
140  std::allocator<_Tp> _M_real_alloc;
141  };
142 
143  // _ExtPtr_allocator<void> specialization.
144  template<>
145  class _ExtPtr_allocator<void>
146  {
147  public:
148  typedef std::size_t size_type;
149  typedef std::ptrdiff_t difference_type;
150  typedef void value_type;
151 
152  // Note the non-standard pointer types
155  const_pointer;
156 
157  template<typename _Up>
158  struct rebind
159  { typedef _ExtPtr_allocator<_Up> other; };
160 
161  private:
162  std::allocator<void> _M_real_alloc;
163  };
164 
165  template<typename _Tp>
166  inline void
167  swap(_ExtPtr_allocator<_Tp>& __larg, _ExtPtr_allocator<_Tp>& __rarg)
168  {
169  std::allocator<_Tp> __tmp( __rarg._M_real_alloc );
170  __rarg._M_real_alloc = __larg._M_real_alloc;
171  __larg._M_real_alloc = __tmp;
172  }
173 
174 _GLIBCXX_END_NAMESPACE
175 
176 #endif /* _EXTPTR_ALLOCATOR_H */