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

   1 // Allocators -*- C++ -*-
   2
   3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2009, 2010, 2011
   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>
  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