1// <extptr_allocator.h> -*- C++ -*-
2
3// Copyright (C) 2008-2015 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
43namespace __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 */
198