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
48namespace __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>
63    class debug_allocator
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:
82      debug_allocator()
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
128