libstdc++

extptr_allocator.h
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1 // <extptr_allocator.h> -*- C++ -*-
2
3 // Copyright (C) 2008-2013 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 * This file is a GNU extension to the Standard C++ Library.
28 *
29 * @author Bob Walters
30 *
31 * An example allocator which uses an alternative pointer type from
32 * bits/pointer.h. Supports test cases which confirm container support
33 * for alternative pointers.
34 */
35
36 #ifndef _EXTPTR_ALLOCATOR_H
37 #define _EXTPTR_ALLOCATOR_H 1
38
39 #include <memory>
40 #include <ext/numeric_traits.h>
41 #include <ext/pointer.h>
42
43 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
44 {
45 _GLIBCXX_BEGIN_NAMESPACE_VERSION
46
47 /**
48 * @brief An example allocator which uses a non-standard pointer type.
49 * @ingroup allocators
50 *
51 * This allocator specifies that containers use a 'relative pointer' as it's
52 * pointer type. (See ext/pointer.h) Memory allocation in this example
53 * is still performed using std::allocator.
54 */
55 template<typename _Tp>
56 class _ExtPtr_allocator
57 {
58 public:
59 typedef std::size_t size_type;
60 typedef std::ptrdiff_t difference_type;
61
62 // Note the non-standard pointer types.
63 typedef _Pointer_adapter<_Relative_pointer_impl<_Tp> > pointer;
64 typedef _Pointer_adapter<_Relative_pointer_impl<const _Tp> >
65 const_pointer;
66
67 typedef _Tp& reference;
68 typedef const _Tp& const_reference;
69 typedef _Tp value_type;
70
71 template<typename _Up>
72 struct rebind
73 { typedef _ExtPtr_allocator<_Up> other; };
74
75 _ExtPtr_allocator() _GLIBCXX_USE_NOEXCEPT
76 : _M_real_alloc() { }
77
78 _ExtPtr_allocator(const _ExtPtr_allocator& __rarg) _GLIBCXX_USE_NOEXCEPT
79 : _M_real_alloc(__rarg._M_real_alloc) { }
80
81 template<typename _Up>
82 _ExtPtr_allocator(const _ExtPtr_allocator<_Up>& __rarg)
83 _GLIBCXX_USE_NOEXCEPT
84 : _M_real_alloc(__rarg._M_getUnderlyingImp()) { }
85
86 ~_ExtPtr_allocator() _GLIBCXX_USE_NOEXCEPT
87 { }
88
89 pointer address(reference __x) const _GLIBCXX_NOEXCEPT
90 { return std::__addressof(__x); }
91
92 const_pointer address(const_reference __x) const _GLIBCXX_NOEXCEPT
93 { return std::__addressof(__x); }
94
95 pointer allocate(size_type __n, void* __hint = 0)
96 { return _M_real_alloc.allocate(__n,__hint); }
97
98 void deallocate(pointer __p, size_type __n)
99 { _M_real_alloc.deallocate(__p.get(), __n); }
100
101 size_type max_size() const _GLIBCXX_USE_NOEXCEPT
102 { return __numeric_traits<size_type>::__max / sizeof(_Tp); }
103
104 #if __cplusplus >= 201103L
105 template<typename _Up, typename... _Args>
106 void
107 construct(_Up* __p, _Args&&... __args)
108 { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
109
110 template<typename... _Args>
111 void
112 construct(pointer __p, _Args&&... __args)
113 { construct(__p.get(), std::forward<_Args>(__args)...); }
114
115 template<typename _Up>
116 void
117 destroy(_Up* __p)
118 { __p->~_Up(); }
119
120 void destroy(pointer __p)
121 { destroy(__p.get()); }
122
123 #else
124
125 void construct(pointer __p, const _Tp& __val)
126 { ::new(__p.get()) _Tp(__val); }
127
128 void destroy(pointer __p)
129 { __p->~_Tp(); }
130 #endif
131
132 template<typename _Up>
133 inline bool
134 operator==(const _ExtPtr_allocator<_Up>& __rarg)
135 { return _M_real_alloc == __rarg._M_getUnderlyingImp(); }
136
137 inline bool
138 operator==(const _ExtPtr_allocator& __rarg)
139 { return _M_real_alloc == __rarg._M_real_alloc; }
140
141 template<typename _Up>
142 inline bool
143 operator!=(const _ExtPtr_allocator<_Up>& __rarg)
144 { return _M_real_alloc != __rarg._M_getUnderlyingImp(); }
145
146 inline bool
147 operator!=(const _ExtPtr_allocator& __rarg)
148 { return _M_real_alloc != __rarg._M_real_alloc; }
149
150 template<typename _Up>
151 inline friend void
152 swap(_ExtPtr_allocator<_Up>&, _ExtPtr_allocator<_Up>&);
153
154 // A method specific to this implementation.
155 const std::allocator<_Tp>&
156 _M_getUnderlyingImp() const
157 { return _M_real_alloc; }
158
159 private:
160 std::allocator<_Tp> _M_real_alloc;
161 };
162
163 // _ExtPtr_allocator<void> specialization.
164 template<>
165 class _ExtPtr_allocator<void>
166 {
167 public:
168 typedef std::size_t size_type;
169 typedef std::ptrdiff_t difference_type;
170 typedef void value_type;
171
172 // Note the non-standard pointer types
173 typedef _Pointer_adapter<_Relative_pointer_impl<void> > pointer;
174 typedef _Pointer_adapter<_Relative_pointer_impl<const void> >
175 const_pointer;
176
177 template<typename _Up>
178 struct rebind
179 { typedef _ExtPtr_allocator<_Up> other; };
180
181 private:
182 std::allocator<void> _M_real_alloc;
183 };
184
185 template<typename _Tp>
186 inline void
187 swap(_ExtPtr_allocator<_Tp>& __larg, _ExtPtr_allocator<_Tp>& __rarg)
188 {
189 std::allocator<_Tp> __tmp( __rarg._M_real_alloc );
190 __rarg._M_real_alloc = __larg._M_real_alloc;
191 __larg._M_real_alloc = __tmp;
192 }
193
194 _GLIBCXX_END_NAMESPACE_VERSION
195 } // namespace
196
197 #endif /* _EXTPTR_ALLOCATOR_H */