libstdc++
debug_allocator.h
Go to the documentation of this file.
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 ext/debug_allocator.h
39  * This file is a GNU extension to the Standard C++ Library.
40  */
41 
42 #ifndef _DEBUG_ALLOCATOR_H
43 #define _DEBUG_ALLOCATOR_H 1
44 
45 #include <stdexcept>
46 #include <bits/functexcept.h>
47 #include <ext/alloc_traits.h>
48 
49 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
50 {
51 _GLIBCXX_BEGIN_NAMESPACE_VERSION
52 
53  using std::size_t;
54 
55  /**
56  * @brief A meta-allocator with debugging bits.
57  * @ingroup allocators
58  *
59  * This is precisely the allocator defined in the C++03 Standard.
60  */
61  template<typename _Alloc>
63  {
64  template<typename> friend class debug_allocator;
65 
67 
68  public:
69  typedef typename _Traits::size_type size_type;
70  typedef typename _Traits::difference_type difference_type;
71  typedef typename _Traits::pointer pointer;
72  typedef typename _Traits::const_pointer const_pointer;
73  typedef typename _Traits::reference reference;
74  typedef typename _Traits::const_reference const_reference;
75  typedef typename _Traits::value_type value_type;
76 
77  template<typename _Up>
78  class rebind
79  {
80  typedef typename _Traits::template rebind<_Up>::other __other;
81 
82  public:
83  typedef debug_allocator<__other> other;
84  };
85 
86  private:
87  // _M_extra is the number of objects that correspond to the
88  // extra space where debug information is stored.
89  size_type _M_extra;
90 
91  _Alloc _M_allocator;
92 
93  template<typename _Alloc2,
94  typename = typename _Alloc2::template rebind<value_type>::other>
95  struct __convertible
96  { };
97 
98  template<typename _Alloc2>
99  struct __convertible<_Alloc2, _Alloc>
100  {
101  typedef void* __type;
102  };
103 
104  size_type _S_extra()
105  {
106  const size_t __obj_size = sizeof(value_type);
107  return (sizeof(size_type) + __obj_size - 1) / __obj_size;
108  }
109 
110  public:
111  debug_allocator() : _M_extra(_S_extra()) { }
112 
113  template<typename _Alloc2>
115  typename __convertible<_Alloc2>::__type = 0)
116  : _M_allocator(__a2._M_allocator), _M_extra(_S_extra()) { }
117 
118  debug_allocator(const _Alloc& __a)
119  : _M_allocator(__a), _M_extra(_S_extra()) { }
120 
121  pointer
122  allocate(size_type __n)
123  {
124  pointer __res = _M_allocator.allocate(__n + _M_extra);
125  size_type* __ps = reinterpret_cast<size_type*>(__res);
126  *__ps = __n;
127  return __res + _M_extra;
128  }
129 
130  pointer
131  allocate(size_type __n, const void* __hint)
132  {
133  pointer __res = _M_allocator.allocate(__n + _M_extra, __hint);
134  size_type* __ps = reinterpret_cast<size_type*>(__res);
135  *__ps = __n;
136  return __res + _M_extra;
137  }
138 
139  void
140  deallocate(pointer __p, size_type __n)
141  {
142  using std::__throw_runtime_error;
143  if (__p)
144  {
145  pointer __real_p = __p - _M_extra;
146  if (*reinterpret_cast<size_type*>(__real_p) != __n)
147  __throw_runtime_error("debug_allocator::deallocate wrong size");
148  _M_allocator.deallocate(__real_p, __n + _M_extra);
149  }
150  else
151  __throw_runtime_error("debug_allocator::deallocate null pointer");
152  }
153 
154  void
155  construct(pointer __p, const value_type& __val)
156  { _Traits::construct(_M_allocator, __p, __val); }
157 
158 #if __cplusplus >= 201103L
159  template<typename _Tp, typename... _Args>
160  void
161  construct(_Tp* __p, _Args&&... __args)
162  {
163  _Traits::construct(_M_allocator, __p,
164  std::forward<_Args>(__args)...);
165  }
166 #endif
167 
168  template<typename _Tp>
169  void
170  destroy(_Tp* __p)
171  { _Traits::destroy(_M_allocator, __p); }
172 
173  size_type
174  max_size() const throw()
175  { return _Traits::max_size(_M_allocator) - _M_extra; }
176 
177  friend bool
178  operator==(const debug_allocator& __lhs, const debug_allocator& __rhs)
179  { return __lhs._M_allocator == __rhs._M_allocator; }
180  };
181 
182  template<typename _Alloc>
183  inline bool
184  operator!=(const debug_allocator<_Alloc>& __lhs,
185  const debug_allocator<_Alloc>& __rhs)
186  { return !(__lhs == __rhs); }
187 
188 _GLIBCXX_END_NAMESPACE_VERSION
189 } // namespace
190 
191 #endif
A meta-allocator with debugging bits.This is precisely the allocator defined in the C++03 Standard...
GNU extensions for public use.
static size_type max_size(const _Alloc &__a) noexcept
The maximum supported allocation size.
Uniform interface to C++98 and C++0x allocators.