libstdc++
debug_allocator.h
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1 // Allocators -*- C++ -*-
2 
3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2009, 2010
4 // 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 ext/debug_allocator.h
40  * This file is a GNU extension to the Standard C++ Library.
41  */
42 
43 #ifndef _DEBUG_ALLOCATOR_H
44 #define _DEBUG_ALLOCATOR_H 1
45 
46 #include <stdexcept>
47 
48 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
49 {
50 _GLIBCXX_BEGIN_NAMESPACE_VERSION
51 
52  using std::size_t;
53 
54  /**
55  * @brief A meta-allocator with debugging bits, as per [20.4].
56  * @ingroup allocators
57  *
58  * This is precisely the allocator defined in the C++ Standard.
59  * - all allocation calls operator new
60  * - all deallocation calls operator delete
61  */
62  template<typename _Alloc>
64  {
65  public:
66  typedef typename _Alloc::size_type size_type;
67  typedef typename _Alloc::difference_type difference_type;
68  typedef typename _Alloc::pointer pointer;
69  typedef typename _Alloc::const_pointer const_pointer;
70  typedef typename _Alloc::reference reference;
71  typedef typename _Alloc::const_reference const_reference;
72  typedef typename _Alloc::value_type value_type;
73 
74  private:
75  // _M_extra is the number of objects that correspond to the
76  // extra space where debug information is stored.
77  size_type _M_extra;
78 
79  _Alloc _M_allocator;
80 
81  public:
83  {
84  const size_t __obj_size = sizeof(value_type);
85  _M_extra = (sizeof(size_type) + __obj_size - 1) / __obj_size;
86  }
87 
88  pointer
89  allocate(size_type __n)
90  {
91  pointer __res = _M_allocator.allocate(__n + _M_extra);
92  size_type* __ps = reinterpret_cast<size_type*>(__res);
93  *__ps = __n;
94  return __res + _M_extra;
95  }
96 
97  pointer
98  allocate(size_type __n, const void* __hint)
99  {
100  pointer __res = _M_allocator.allocate(__n + _M_extra, __hint);
101  size_type* __ps = reinterpret_cast<size_type*>(__res);
102  *__ps = __n;
103  return __res + _M_extra;
104  }
105 
106  void
107  deallocate(pointer __p, size_type __n)
108  {
109  if (__p)
110  {
111  pointer __real_p = __p - _M_extra;
112  if (*reinterpret_cast<size_type*>(__real_p) != __n)
113  {
114  throw std::runtime_error("debug_allocator::deallocate"
115  " wrong size");
116  }
117  _M_allocator.deallocate(__real_p, __n + _M_extra);
118  }
119  else
120  throw std::runtime_error("debug_allocator::deallocate null pointer");
121  }
122  };
123 
124 _GLIBCXX_END_NAMESPACE_VERSION
125 } // namespace
126 
127 #endif