libstdc++
debug_allocator.h
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00001 // Allocators -*- C++ -*-
00002 
00003 // Copyright (C) 2001-2015 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  */
00041 
00042 #ifndef _DEBUG_ALLOCATOR_H
00043 #define _DEBUG_ALLOCATOR_H 1
00044 
00045 #include <stdexcept>
00046 #include <bits/functexcept.h>
00047 #include <ext/alloc_traits.h>
00048 
00049 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
00050 {
00051 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00052 
00053   using std::size_t;
00054 
00055   /**
00056    *  @brief  A meta-allocator with debugging bits.
00057    *  @ingroup allocators
00058    *
00059    *  This is precisely the allocator defined in the C++03 Standard.
00060    */
00061   template<typename _Alloc>
00062     class debug_allocator
00063     {
00064       template<typename> friend class debug_allocator;
00065 
00066       typedef __alloc_traits<_Alloc> _Traits;
00067 
00068     public:
00069       typedef typename _Traits::size_type               size_type;
00070       typedef typename _Traits::difference_type difference_type;
00071       typedef typename _Traits::pointer         pointer;
00072       typedef typename _Traits::const_pointer    const_pointer;
00073       typedef typename _Traits::reference               reference;
00074       typedef typename _Traits::const_reference  const_reference;
00075       typedef typename _Traits::value_type       value_type;
00076 
00077       template<typename _Up>
00078         class rebind
00079         {
00080           typedef typename _Traits::template rebind<_Up>::other __other;
00081 
00082         public:
00083           typedef debug_allocator<__other> other;
00084         };
00085 
00086     private:
00087       // _M_extra is the number of objects that correspond to the
00088       // extra space where debug information is stored.
00089       size_type                 _M_extra;
00090       
00091       _Alloc                    _M_allocator;
00092 
00093       template<typename _Alloc2,
00094                typename = typename _Alloc2::template rebind<value_type>::other>
00095         struct __convertible
00096         { };
00097 
00098       template<typename _Alloc2>
00099         struct __convertible<_Alloc2, _Alloc>
00100         {
00101           typedef void* __type;
00102         };
00103 
00104       size_type _S_extra()
00105       {
00106         const size_t __obj_size = sizeof(value_type);
00107         return (sizeof(size_type) + __obj_size - 1) / __obj_size; 
00108       }
00109 
00110     public:
00111       debug_allocator() : _M_extra(_S_extra()) { }
00112 
00113       template<typename _Alloc2>
00114         debug_allocator(const debug_allocator<_Alloc2>& __a2,
00115                         typename __convertible<_Alloc2>::__type = 0)
00116         : _M_allocator(__a2._M_allocator), _M_extra(_S_extra()) { }
00117 
00118       debug_allocator(const _Alloc& __a)
00119       : _M_allocator(__a), _M_extra(_S_extra()) { }
00120 
00121       pointer
00122       allocate(size_type __n)
00123       {
00124         pointer __res = _M_allocator.allocate(__n + _M_extra);      
00125         size_type* __ps = reinterpret_cast<size_type*>(__res);
00126         *__ps = __n;
00127         return __res + _M_extra;
00128       }
00129 
00130       pointer
00131       allocate(size_type __n, const void* __hint)
00132       {
00133         pointer __res = _M_allocator.allocate(__n + _M_extra, __hint);
00134         size_type* __ps = reinterpret_cast<size_type*>(__res);
00135         *__ps = __n;
00136         return __res + _M_extra;
00137       }
00138 
00139       void
00140       deallocate(pointer __p, size_type __n)
00141       {
00142         using std::__throw_runtime_error;
00143         if (__p)
00144           {
00145             pointer __real_p = __p - _M_extra;
00146             if (*reinterpret_cast<size_type*>(__real_p) != __n)
00147               __throw_runtime_error("debug_allocator::deallocate wrong size");
00148             _M_allocator.deallocate(__real_p, __n + _M_extra);
00149           }
00150         else
00151           __throw_runtime_error("debug_allocator::deallocate null pointer");
00152       }
00153 
00154       void
00155       construct(pointer __p, const value_type& __val)
00156       { _Traits::construct(_M_allocator, __p, __val); }
00157 
00158 #if __cplusplus >= 201103L
00159       template<typename _Tp, typename... _Args>
00160         void
00161         construct(_Tp* __p, _Args&&... __args)
00162         {
00163           _Traits::construct(_M_allocator, __p,
00164                              std::forward<_Args>(__args)...);
00165         }
00166 #endif
00167 
00168       template<typename _Tp>
00169         void
00170         destroy(_Tp* __p)
00171         { _Traits::destroy(_M_allocator, __p); }
00172 
00173       size_type
00174       max_size() const throw()
00175       { return _Traits::max_size(_M_allocator) - _M_extra; }
00176 
00177       friend bool
00178       operator==(const debug_allocator& __lhs, const debug_allocator& __rhs)
00179       { return __lhs._M_allocator == __rhs._M_allocator; }
00180     };
00181 
00182   template<typename _Alloc>
00183     inline bool
00184     operator!=(const debug_allocator<_Alloc>& __lhs,
00185                const debug_allocator<_Alloc>& __rhs)
00186     { return !(__lhs == __rhs); }
00187 
00188 _GLIBCXX_END_NAMESPACE_VERSION
00189 } // namespace
00190 
00191 #endif