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