libstdc++
allocator.h
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1 // Allocators -*- C++ -*-
2 
3 // Copyright (C) 2001-2013 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  * Copyright (c) 1996-1997
27  * Silicon Graphics Computer Systems, Inc.
28  *
29  * Permission to use, copy, modify, distribute and sell this software
30  * and its documentation for any purpose is hereby granted without fee,
31  * provided that the above copyright notice appear in all copies and
32  * that both that copyright notice and this permission notice appear
33  * in supporting documentation. Silicon Graphics makes no
34  * representations about the suitability of this software for any
35  * purpose. It is provided "as is" without express or implied warranty.
36  */
37 
38 /** @file bits/allocator.h
39  * This is an internal header file, included by other library headers.
40  * Do not attempt to use it directly. @headername{memory}
41  */
42 
43 #ifndef _ALLOCATOR_H
44 #define _ALLOCATOR_H 1
45 
46 // Define the base class to std::allocator.
47 #include <bits/c++allocator.h>
48 #if __cplusplus >= 201103L
49 #include <type_traits>
50 #endif
51 
52 namespace std _GLIBCXX_VISIBILITY(default)
53 {
54 _GLIBCXX_BEGIN_NAMESPACE_VERSION
55 
56  /**
57  * @defgroup allocators Allocators
58  * @ingroup memory
59  *
60  * Classes encapsulating memory operations.
61  *
62  * @{
63  */
64 
65  template<typename _Tp>
66  class allocator;
67 
68  /// allocator<void> specialization.
69  template<>
70  class allocator<void>
71  {
72  public:
73  typedef size_t size_type;
74  typedef ptrdiff_t difference_type;
75  typedef void* pointer;
76  typedef const void* const_pointer;
77  typedef void value_type;
78 
79  template<typename _Tp1>
80  struct rebind
81  { typedef allocator<_Tp1> other; };
82 
83 #if __cplusplus >= 201103L
84  // _GLIBCXX_RESOLVE_LIB_DEFECTS
85  // 2103. std::allocator propagate_on_container_move_assignment
87 #endif
88  };
89 
90  /**
91  * @brief The @a standard allocator, as per [20.4].
92  *
93  * See http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt04ch11.html
94  * for further details.
95  *
96  * @tparam _Tp Type of allocated object.
97  */
98  template<typename _Tp>
99  class allocator: public __allocator_base<_Tp>
100  {
101  public:
102  typedef size_t size_type;
103  typedef ptrdiff_t difference_type;
104  typedef _Tp* pointer;
105  typedef const _Tp* const_pointer;
106  typedef _Tp& reference;
107  typedef const _Tp& const_reference;
108  typedef _Tp value_type;
109 
110  template<typename _Tp1>
111  struct rebind
112  { typedef allocator<_Tp1> other; };
113 
114 #if __cplusplus >= 201103L
115  // _GLIBCXX_RESOLVE_LIB_DEFECTS
116  // 2103. std::allocator propagate_on_container_move_assignment
118 #endif
119 
120  allocator() throw() { }
121 
122  allocator(const allocator& __a) throw()
123  : __allocator_base<_Tp>(__a) { }
124 
125  template<typename _Tp1>
126  allocator(const allocator<_Tp1>&) throw() { }
127 
128  ~allocator() throw() { }
129 
130  // Inherit everything else.
131  };
132 
133  template<typename _T1, typename _T2>
134  inline bool
135  operator==(const allocator<_T1>&, const allocator<_T2>&)
136  { return true; }
137 
138  template<typename _Tp>
139  inline bool
140  operator==(const allocator<_Tp>&, const allocator<_Tp>&)
141  { return true; }
142 
143  template<typename _T1, typename _T2>
144  inline bool
145  operator!=(const allocator<_T1>&, const allocator<_T2>&)
146  { return false; }
147 
148  template<typename _Tp>
149  inline bool
150  operator!=(const allocator<_Tp>&, const allocator<_Tp>&)
151  { return false; }
152 
153  /// Declare uses_allocator so it can be specialized in <queue> etc.
154  template<typename, typename>
156 
157  /**
158  * @}
159  */
160 
161  // Inhibit implicit instantiations for required instantiations,
162  // which are defined via explicit instantiations elsewhere.
163 #if _GLIBCXX_EXTERN_TEMPLATE
164  extern template class allocator<char>;
165  extern template class allocator<wchar_t>;
166 #endif
167 
168  // Undefine.
169 #undef __allocator_base
170 
171  // To implement Option 3 of DR 431.
172  template<typename _Alloc, bool = __is_empty(_Alloc)>
173  struct __alloc_swap
174  { static void _S_do_it(_Alloc&, _Alloc&) { } };
175 
176  template<typename _Alloc>
177  struct __alloc_swap<_Alloc, false>
178  {
179  static void
180  _S_do_it(_Alloc& __one, _Alloc& __two)
181  {
182  // Precondition: swappable allocators.
183  if (__one != __two)
184  swap(__one, __two);
185  }
186  };
187 
188  // Optimize for stateless allocators.
189  template<typename _Alloc, bool = __is_empty(_Alloc)>
190  struct __alloc_neq
191  {
192  static bool
193  _S_do_it(const _Alloc&, const _Alloc&)
194  { return false; }
195  };
196 
197  template<typename _Alloc>
198  struct __alloc_neq<_Alloc, false>
199  {
200  static bool
201  _S_do_it(const _Alloc& __one, const _Alloc& __two)
202  { return __one != __two; }
203  };
204 
205 #if __cplusplus >= 201103L
206  template<typename _Tp, bool
207  = __or_<is_copy_constructible<typename _Tp::value_type>,
208  is_nothrow_move_constructible<typename _Tp::value_type>>::value>
209  struct __shrink_to_fit_aux
210  { static bool _S_do_it(_Tp&) { return false; } };
211 
212  template<typename _Tp>
213  struct __shrink_to_fit_aux<_Tp, true>
214  {
215  static bool
216  _S_do_it(_Tp& __c)
217  {
218  __try
219  {
220  _Tp(__make_move_if_noexcept_iterator(__c.begin()),
221  __make_move_if_noexcept_iterator(__c.end()),
222  __c.get_allocator()).swap(__c);
223  return true;
224  }
225  __catch(...)
226  { return false; }
227  }
228  };
229 #endif
230 
231 _GLIBCXX_END_NAMESPACE_VERSION
232 } // namespace std
233 
234 #endif