1// Allocators -*- C++ -*-
2
3// Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
4// 2011 Free Software Foundation, Inc.
5//
6// This file is part of the GNU ISO C++ Library.  This library is free
7// software; you can redistribute it and/or modify it under the
8// terms of the GNU General Public License as published by the
9// Free Software Foundation; either version 3, or (at your option)
10// any later version.
11
12// This library is distributed in the hope that it will be useful,
13// but WITHOUT ANY WARRANTY; without even the implied warranty of
14// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15// GNU General Public License for more details.
16
17// Under Section 7 of GPL version 3, you are granted additional
18// permissions described in the GCC Runtime Library Exception, version
19// 3.1, as published by the Free Software Foundation.
20
21// You should have received a copy of the GNU General Public License and
22// a copy of the GCC Runtime Library Exception along with this program;
23// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
24// <http://www.gnu.org/licenses/>.
25
26/*
27 * Copyright (c) 1996-1997
28 * Silicon Graphics Computer Systems, Inc.
29 *
30 * Permission to use, copy, modify, distribute and sell this software
31 * and its documentation for any purpose is hereby granted without fee,
32 * provided that the above copyright notice appear in all copies and
33 * that both that copyright notice and this permission notice appear
34 * in supporting documentation.  Silicon Graphics makes no
35 * representations about the suitability of this software for any
36 * purpose.  It is provided "as is" without express or implied warranty.
37 */
38
39/** @file bits/allocator.h
40 *  This is an internal header file, included by other library headers.
41 *  Do not attempt to use it directly. @headername{memory}
42 */
43
44#ifndef _ALLOCATOR_H
45#define _ALLOCATOR_H 1
46
47// Define the base class to std::allocator.
48#include <bits/c++allocator.h>
49
50#ifdef __GXX_EXPERIMENTAL_CXX0X__
51#include <type_traits> // For _GLIBCXX_HAS_NESTED_TYPE
52#endif
53
54namespace std _GLIBCXX_VISIBILITY(default)
55{
56_GLIBCXX_BEGIN_NAMESPACE_VERSION
57
58  /**
59   * @defgroup allocators Allocators
60   * @ingroup memory
61   *
62   * Classes encapsulating memory operations.
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
84  /**
85   * @brief  The @a standard allocator, as per [20.4].
86   * @ingroup allocators
87   *
88   *  Further details:
89   *  http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt04ch11.html
90   */
91  template<typename _Tp>
92    class allocator: public __glibcxx_base_allocator<_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      allocator() throw() { }
108
109      allocator(const allocator& __a) throw()
110      : __glibcxx_base_allocator<_Tp>(__a) { }
111
112      template<typename _Tp1>
113        allocator(const allocator<_Tp1>&) throw() { }
114
115      ~allocator() throw() { }
116
117      // Inherit everything else.
118    };
119
120  template<typename _T1, typename _T2>
121    inline bool
122    operator==(const allocator<_T1>&, const allocator<_T2>&)
123    { return true; }
124
125  template<typename _Tp>
126    inline bool
127    operator==(const allocator<_Tp>&, const allocator<_Tp>&)
128    { return true; }
129
130  template<typename _T1, typename _T2>
131    inline bool
132    operator!=(const allocator<_T1>&, const allocator<_T2>&)
133    { return false; }
134
135  template<typename _Tp>
136    inline bool
137    operator!=(const allocator<_Tp>&, const allocator<_Tp>&)
138    { return false; }
139
140  // Inhibit implicit instantiations for required instantiations,
141  // which are defined via explicit instantiations elsewhere.
142#if _GLIBCXX_EXTERN_TEMPLATE
143  extern template class allocator<char>;
144  extern template class allocator<wchar_t>;
145#endif
146
147  // Undefine.
148#undef __glibcxx_base_allocator
149
150  // To implement Option 3 of DR 431.
151  template<typename _Alloc, bool = __is_empty(_Alloc)>
152    struct __alloc_swap
153    { static void _S_do_it(_Alloc&, _Alloc&) { } };
154
155  template<typename _Alloc>
156    struct __alloc_swap<_Alloc, false>
157    {
158      static void
159      _S_do_it(_Alloc& __one, _Alloc& __two)
160      {
161	// Precondition: swappable allocators.
162	if (__one != __two)
163	  swap(__one, __two);
164      }
165    };
166
167  // Optimize for stateless allocators.
168  template<typename _Alloc, bool = __is_empty(_Alloc)>
169    struct __alloc_neq
170    {
171      static bool
172      _S_do_it(const _Alloc&, const _Alloc&)
173      { return false; }
174    };
175
176  template<typename _Alloc>
177    struct __alloc_neq<_Alloc, false>
178    {
179      static bool
180      _S_do_it(const _Alloc& __one, const _Alloc& __two)
181      { return __one != __two; }
182    };
183
184#ifdef __GXX_EXPERIMENTAL_CXX0X__
185  // A very basic implementation for now.  In general we have to wait for
186  // the availability of the infrastructure described in N2983:  we should
187  // try when either T has a move constructor which cannot throw or T is
188  // CopyContructible.
189  // NB: This code doesn't properly belong here, we should find a more
190  // suited place common to std::vector and std::deque.
191  template<typename _Tp,
192	   bool = __has_trivial_copy(typename _Tp::value_type)>
193    struct __shrink_to_fit
194    { static void _S_do_it(_Tp&) { } };
195
196  template<typename _Tp>
197    struct __shrink_to_fit<_Tp, true>
198    {
199      static void
200      _S_do_it(_Tp& __v)
201      {
202	__try
203	  { _Tp(__v).swap(__v); }
204	__catch(...) { }
205      }
206    };
207
208
209  /// [allocator.tag]
210  struct allocator_arg_t { };
211
212  constexpr allocator_arg_t allocator_arg = allocator_arg_t();
213
214_GLIBCXX_HAS_NESTED_TYPE(allocator_type)
215
216  template<typename _Tp, typename _Alloc,
217	   bool = __has_allocator_type<_Tp>::value>
218    struct __uses_allocator_helper
219    : public false_type { };
220
221  template<typename _Tp, typename _Alloc>
222    struct __uses_allocator_helper<_Tp, _Alloc, true>
223    : public integral_constant<bool, is_convertible<_Alloc,
224				     typename _Tp::allocator_type>::value>
225    { };
226
227  /// [allocator.uses.trait]
228  template<typename _Tp, typename _Alloc>
229    struct uses_allocator
230    : public integral_constant<bool,
231			       __uses_allocator_helper<_Tp, _Alloc>::value>
232    { };
233
234#endif
235
236_GLIBCXX_END_NAMESPACE_VERSION
237} // namespace std
238
239#endif
240