libstdc++-v3/include/ext/debug_allocator.h

   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>
  61     class debug_allocator
  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