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,
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 #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 
81  template<typename _Up, typename... _Args>
82  void
83  construct(_Up* __p, _Args&&... __args)
84  { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
85 
86  template<typename _Up>
87  void
88  destroy(_Up* __p) { __p->~_Up(); }
89 #endif
90  };
91 
92  /**
93  * @brief The @a standard allocator, as per [20.4].
94  *
95  * See https://gcc.gnu.org/onlinedocs/libstdc++/manual/memory.html#std.util.memory.allocator
96  * for further details.
97  *
98  * @tparam _Tp Type of allocated object.
99  */
100  template<typename _Tp>
101  class allocator: public __allocator_base<_Tp>
102  {
103  public:
104  typedef size_t size_type;
105  typedef ptrdiff_t difference_type;
106  typedef _Tp* pointer;
107  typedef const _Tp* const_pointer;
108  typedef _Tp& reference;
109  typedef const _Tp& const_reference;
110  typedef _Tp value_type;
111 
112  template<typename _Tp1>
113  struct rebind
114  { typedef allocator<_Tp1> other; };
115 
116 #if __cplusplus >= 201103L
117  // _GLIBCXX_RESOLVE_LIB_DEFECTS
118  // 2103. std::allocator propagate_on_container_move_assignment
120 #endif
121 
122  allocator() throw() { }
123 
124  allocator(const allocator& __a) throw()
125  : __allocator_base<_Tp>(__a) { }
126 
127  template<typename _Tp1>
128  allocator(const allocator<_Tp1>&) throw() { }
129 
130  ~allocator() throw() { }
131 
132  // Inherit everything else.
133  };
134 
135  template<typename _T1, typename _T2>
136  inline bool
137  operator==(const allocator<_T1>&, const allocator<_T2>&)
138  _GLIBCXX_USE_NOEXCEPT
139  { return true; }
140 
141  template<typename _Tp>
142  inline bool
143  operator==(const allocator<_Tp>&, const allocator<_Tp>&)
144  _GLIBCXX_USE_NOEXCEPT
145  { return true; }
146 
147  template<typename _T1, typename _T2>
148  inline bool
149  operator!=(const allocator<_T1>&, const allocator<_T2>&)
150  _GLIBCXX_USE_NOEXCEPT
151  { return false; }
152 
153  template<typename _Tp>
154  inline bool
155  operator!=(const allocator<_Tp>&, const allocator<_Tp>&)
156  _GLIBCXX_USE_NOEXCEPT
157  { return false; }
158 
159  /// @} group allocator
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&) _GLIBCXX_NOEXCEPT { } };
175 
176  template<typename _Alloc>
177  struct __alloc_swap<_Alloc, false>
178  {
179  static void
180  _S_do_it(_Alloc& __one, _Alloc& __two) _GLIBCXX_NOEXCEPT
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&) noexcept { 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) noexcept
217  {
218 #if __cpp_exceptions
219  try
220  {
221  _Tp(__make_move_if_noexcept_iterator(__c.begin()),
222  __make_move_if_noexcept_iterator(__c.end()),
223  __c.get_allocator()).swap(__c);
224  return true;
225  }
226  catch(...)
227  { return false; }
228 #else
229  return false;
230 #endif
231  }
232  };
233 #endif
234 
235 _GLIBCXX_END_NAMESPACE_VERSION
236 } // namespace std
237 
238 #endif
integral_constant
Definition: type_traits:69
An allocator that uses global new, as per [20.4].This is precisely the allocator defined in the C++ S...
ISO C++ entities toplevel namespace is std.
The standard allocator, as per [20.4].
Definition: allocator.h:101