libstdc++
allocator.h
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1 // Allocators -*- C++ -*-
2 
3 // Copyright (C) 2001-2015 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,
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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 
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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
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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 #include <bits/c++allocator.h> // Define the base class to std::allocator.
47 #include <bits/memoryfwd.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  * @addtogroup allocators
58  * @{
59  */
60 
61  /// allocator<void> specialization.
62  template<>
63  class allocator<void>
64  {
65  public:
66  typedef size_t size_type;
67  typedef ptrdiff_t difference_type;
68  typedef void* pointer;
69  typedef const void* const_pointer;
70  typedef void value_type;
71 
72  template<typename _Tp1>
73  struct rebind
74  { typedef allocator<_Tp1> other; };
75 
76 #if __cplusplus >= 201103L
77  // _GLIBCXX_RESOLVE_LIB_DEFECTS
78  // 2103. std::allocator propagate_on_container_move_assignment
80 #endif
81  };
82 
83  /**
84  * @brief The @a standard allocator, as per [20.4].
85  *
86  * See https://gcc.gnu.org/onlinedocs/libstdc++/manual/memory.html#std.util.memory.allocator
87  * for further details.
88  *
89  * @tparam _Tp Type of allocated object.
90  */
91  template<typename _Tp>
92  class allocator: public __allocator_base<_Tp>
93  {
94  public:
95  typedef size_t size_type;
96  typedef ptrdiff_t difference_type;
97  typedef _Tp* pointer;
98  typedef const _Tp* const_pointer;
99  typedef _Tp& reference;
100  typedef const _Tp& const_reference;
101  typedef _Tp value_type;
102 
103  template<typename _Tp1>
104  struct rebind
105  { typedef allocator<_Tp1> other; };
106 
107 #if __cplusplus >= 201103L
108  // _GLIBCXX_RESOLVE_LIB_DEFECTS
109  // 2103. std::allocator propagate_on_container_move_assignment
111 #endif
112 
113  allocator() throw() { }
114 
115  allocator(const allocator& __a) throw()
116  : __allocator_base<_Tp>(__a) { }
117 
118  template<typename _Tp1>
119  allocator(const allocator<_Tp1>&) throw() { }
120 
121  ~allocator() throw() { }
122 
123  // Inherit everything else.
124  };
125 
126  template<typename _T1, typename _T2>
127  inline bool
128  operator==(const allocator<_T1>&, const allocator<_T2>&)
129  _GLIBCXX_USE_NOEXCEPT
130  { return true; }
131 
132  template<typename _Tp>
133  inline bool
134  operator==(const allocator<_Tp>&, const allocator<_Tp>&)
135  _GLIBCXX_USE_NOEXCEPT
136  { return true; }
137 
138  template<typename _T1, typename _T2>
139  inline bool
140  operator!=(const allocator<_T1>&, const allocator<_T2>&)
141  _GLIBCXX_USE_NOEXCEPT
142  { return false; }
143 
144  template<typename _Tp>
145  inline bool
146  operator!=(const allocator<_Tp>&, const allocator<_Tp>&)
147  _GLIBCXX_USE_NOEXCEPT
148  { return false; }
149 
150  /// @} group allocator
151 
152  // Inhibit implicit instantiations for required instantiations,
153  // which are defined via explicit instantiations elsewhere.
154 #if _GLIBCXX_EXTERN_TEMPLATE
155  extern template class allocator<char>;
156  extern template class allocator<wchar_t>;
157 #endif
158 
159  // Undefine.
160 #undef __allocator_base
161 
162  // To implement Option 3 of DR 431.
163  template<typename _Alloc, bool = __is_empty(_Alloc)>
164  struct __alloc_swap
165  { static void _S_do_it(_Alloc&, _Alloc&) _GLIBCXX_NOEXCEPT { } };
166 
167  template<typename _Alloc>
168  struct __alloc_swap<_Alloc, false>
169  {
170  static void
171  _S_do_it(_Alloc& __one, _Alloc& __two) _GLIBCXX_NOEXCEPT
172  {
173  // Precondition: swappable allocators.
174  if (__one != __two)
175  swap(__one, __two);
176  }
177  };
178 
179  // Optimize for stateless allocators.
180  template<typename _Alloc, bool = __is_empty(_Alloc)>
181  struct __alloc_neq
182  {
183  static bool
184  _S_do_it(const _Alloc&, const _Alloc&)
185  { return false; }
186  };
187 
188  template<typename _Alloc>
189  struct __alloc_neq<_Alloc, false>
190  {
191  static bool
192  _S_do_it(const _Alloc& __one, const _Alloc& __two)
193  { return __one != __two; }
194  };
195 
196 #if __cplusplus >= 201103L
197  template<typename _Tp, bool
198  = __or_<is_copy_constructible<typename _Tp::value_type>,
199  is_nothrow_move_constructible<typename _Tp::value_type>>::value>
200  struct __shrink_to_fit_aux
201  { static bool _S_do_it(_Tp&) noexcept { return false; } };
202 
203  template<typename _Tp>
204  struct __shrink_to_fit_aux<_Tp, true>
205  {
206  static bool
207  _S_do_it(_Tp& __c) noexcept
208  {
209 #if __cpp_exceptions
210  try
211  {
212  _Tp(__make_move_if_noexcept_iterator(__c.begin()),
213  __make_move_if_noexcept_iterator(__c.end()),
214  __c.get_allocator()).swap(__c);
215  return true;
216  }
217  catch(...)
218  { return false; }
219 #else
220  return false;
221 #endif
222  }
223  };
224 #endif
225 
226 _GLIBCXX_END_NAMESPACE_VERSION
227 } // namespace std
228 
229 #endif
An allocator that uses global new, as per [20.4].This is precisely the allocator defined in the C++ S...
The standard allocator, as per [20.4].
Definition: allocator.h:92
integral_constant
Definition: type_traits:69
ISO C++ entities toplevel namespace is std.