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  1. // Allocators -*- C++ -*-
  2.  
  3. // Copyright (C) 2001-2013 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.  */
  41.  
  42. #ifndef _DEBUG_ALLOCATOR_H
  43. #define _DEBUG_ALLOCATOR_H 1
  44.  
  45. #include <stdexcept>
  46.  
  47. namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
  48. {
  49. _GLIBCXX_BEGIN_NAMESPACE_VERSION
  50.  
  51.   using std::size_t;
  52.  
  53.   /**
  54.    *  @brief  A meta-allocator with debugging bits, as per [20.4].
  55.    *  @ingroup allocators
  56.    *
  57.    *  This is precisely the allocator defined in the C++ Standard.
  58.    *    - all allocation calls operator new
  59.    *    - all deallocation calls operator delete
  60.    */
  61.   template<typename _Alloc>
  62.     class debug_allocator
  63.     {
  64.     public:
  65.       typedef typename _Alloc::size_type        size_type;
  66.       typedef typename _Alloc::difference_type  difference_type;
  67.       typedef typename _Alloc::pointer          pointer;
  68.       typedef typename _Alloc::const_pointer    const_pointer;
  69.       typedef typename _Alloc::reference        reference;
  70.       typedef typename _Alloc::const_reference  const_reference;
  71.       typedef typename _Alloc::value_type       value_type;
  72.  
  73.     private:
  74.       // _M_extra is the number of objects that correspond to the
  75.       // extra space where debug information is stored.
  76.       size_type                 _M_extra;
  77.      
  78.       _Alloc                    _M_allocator;
  79.  
  80.     public:
  81.       debug_allocator()
  82.       {
  83.         const size_t __obj_size = sizeof(value_type);
  84.         _M_extra = (sizeof(size_type) + __obj_size - 1) / __obj_size;
  85.       }
  86.      
  87.       pointer
  88.       allocate(size_type __n)
  89.       {
  90.         pointer __res = _M_allocator.allocate(__n + _M_extra);      
  91.         size_type* __ps = reinterpret_cast<size_type*>(__res);
  92.         *__ps = __n;
  93.         return __res + _M_extra;
  94.       }
  95.  
  96.       pointer
  97.       allocate(size_type __n, const void* __hint)
  98.       {
  99.         pointer __res = _M_allocator.allocate(__n + _M_extra, __hint);
  100.         size_type* __ps = reinterpret_cast<size_type*>(__res);
  101.         *__ps = __n;
  102.         return __res + _M_extra;
  103.       }
  104.  
  105.       void
  106.       deallocate(pointer __p, size_type __n)
  107.       {
  108.         if (__p)
  109.           {
  110.             pointer __real_p = __p - _M_extra;
  111.             if (*reinterpret_cast<size_type*>(__real_p) != __n)
  112.               {
  113.                 throw std::runtime_error("debug_allocator::deallocate"
  114.                                          " wrong size");
  115.               }
  116.             _M_allocator.deallocate(__real_p, __n + _M_extra);
  117.           }
  118.         else
  119.           throw std::runtime_error("debug_allocator::deallocate null pointer");
  120.       }
  121.     };
  122.  
  123. _GLIBCXX_END_NAMESPACE_VERSION
  124. } // namespace
  125.  
  126. #endif
  127.