# debug_allocator.h

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    00001 // Allocators -*- C++ -*-
    00002
    00003 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2009 Free Software Foundation, Inc.
    00004 //
    00005 // This file is part of the GNU ISO C++ Library.  This library is free
    00006 // software; you can redistribute it and/or modify it under the
    00007 // terms of the GNU General Public License as published by the
    00008 // Free Software Foundation; either version 3, or (at your option)
    00009 // any later version.
    00010
    00011 // This library is distributed in the hope that it will be useful,
    00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
    00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    00014 // GNU General Public License for more details.
    00015
    00016 // Under Section 7 of GPL version 3, you are granted additional
    00017 // permissions described in the GCC Runtime Library Exception, version
    00018 // 3.1, as published by the Free Software Foundation.
    00019
    00020 // You should have received a copy of the GNU General Public License and
    00021 // a copy of the GCC Runtime Library Exception along with this program;
    00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
    00023 // <http://www.gnu.org/licenses/>.
    00024
    00025 /*
    00026  * Copyright (c) 1996-1997
    00027  * Silicon Graphics Computer Systems, Inc.
    00028  *
    00029  * Permission to use, copy, modify, distribute and sell this software
    00030  * and its documentation for any purpose is hereby granted without fee,
    00031  * provided that the above copyright notice appear in all copies and
    00032  * that both that copyright notice and this permission notice appear
    00033  * in supporting documentation.  Silicon Graphics makes no
    00034  * representations about the suitability of this software for any
    00035  * purpose.  It is provided "as is" without express or implied warranty.
    00036  */
    00037
    00038 /** @file ext/debug_allocator.h
    00039  *  This file is a GNU extension to the Standard C++ Library.
    00040  *  You should only include this header if you are using GCC 3 or later.
    00041  */
    00042
    00043 #ifndef _DEBUG_ALLOCATOR_H
    00044 #define _DEBUG_ALLOCATOR_H 1
    00045
    00046 #include <stdexcept>
    00047
    00048 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
    00049
    00050   using std::size_t;
    00051
    00052   /**
    00053    *  @brief  A meta-allocator with debugging bits, as per [20.4].
    00054    *  @ingroup allocators
    00055    *
    00056    *  This is precisely the allocator defined in the C++ Standard.
    00057    *    - all allocation calls operator new
    00058    *    - all deallocation calls operator delete
    00059    */
    00060   template<typename _Alloc>
    00061     class debug_allocator
    00062     {
    00063     public:
    00064       typedef typename _Alloc::size_type        size_type;
    00065       typedef typename _Alloc::difference_type  difference_type;
    00066       typedef typename _Alloc::pointer          pointer;
    00067       typedef typename _Alloc::const_pointer    const_pointer;
    00068       typedef typename _Alloc::reference        reference;
    00069       typedef typename _Alloc::const_reference  const_reference;
    00070       typedef typename _Alloc::value_type       value_type;
    00071
    00072     private:
    00073       // _M_extra is the number of objects that correspond to the
    00074       // extra space where debug information is stored.
    00075       size_type         _M_extra;
    00076
    00077       _Alloc            _M_allocator;
    00078
    00079     public:
    00080       debug_allocator()
    00081       {
    00082     const size_t __obj_size = sizeof(value_type);
    00083     _M_extra = (sizeof(size_type) + __obj_size - 1) / __obj_size;
    00084       }
    00085
    00086       pointer
    00087       allocate(size_type __n)
    00088       {
    00089         pointer __res = _M_allocator.allocate(__n + _M_extra);
    00090     size_type* __ps = reinterpret_cast<size_type*>(__res);
    00091     *__ps = __n;
    00092         return __res + _M_extra;
    00093       }
    00094
    00095       pointer
    00096       allocate(size_type __n, const void* __hint)
    00097       {
    00098         pointer __res = _M_allocator.allocate(__n + _M_extra, __hint);
    00099     size_type* __ps = reinterpret_cast<size_type*>(__res);
    00100     *__ps = __n;
    00101         return __res + _M_extra;
    00102       }
    00103
    00104       void
    00105       deallocate(pointer __p, size_type __n)
    00106       {
    00107     if (__p)
    00108       {
    00109         pointer __real_p = __p - _M_extra;
    00110         if (*reinterpret_cast<size_type*>(__real_p) != __n)
    00111           {
    00112         throw std::runtime_error("debug_allocator::deallocate"
    00113                      " wrong size");
    00114           }
    00115         _M_allocator.deallocate(__real_p, __n + _M_extra);
    00116       }
    00117     else
    00118       throw std::runtime_error("debug_allocator::deallocate null pointer");
    00119       }
    00120     };
    00121
    00122 _GLIBCXX_END_NAMESPACE
    00123
    00124 #endif