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

   1 // Allocators -*- C++ -*-
   2
   3 // Copyright (C) 2001-2022 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 <bits/requires_hosted.h> // GNU extensions are currently omitted
  46
  47 #include <stdexcept>
  48 #include <bits/functexcept.h>
  49 #include <ext/alloc_traits.h>
  50
  51 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
  52 {
  53 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  54
  55   /**
  56    *  @brief  A meta-allocator with debugging bits.
  57    *  @ingroup allocators
  58    *
  59    *  This is precisely the allocator defined in the C++03 Standard.
  60    */
  61   template<typename _Alloc>
  62     class debug_allocator
  63     {
  64       template<typename> friend class debug_allocator;
  65
  66       typedef __alloc_traits<_Alloc> _Traits;
  67
  68     public:
  69       typedef typename _Traits::size_type               size_type;
  70       typedef typename _Traits::difference_type difference_type;
  71       typedef typename _Traits::pointer         pointer;
  72       typedef typename _Traits::const_pointer    const_pointer;
  73       typedef typename _Traits::reference               reference;
  74       typedef typename _Traits::const_reference  const_reference;
  75       typedef typename _Traits::value_type       value_type;
  76
  77       template<typename _Up>
  78         class rebind
  79         {
  80           typedef typename _Traits::template rebind<_Up>::other __other;
  81
  82         public:
  83           typedef debug_allocator<__other> other;
  84         };
  85
  86     private:
  87       // _M_extra is the number of objects that correspond to the
  88       // extra space where debug information is stored.
  89       size_type                 _M_extra;
  90
  91       _Alloc                    _M_allocator;
  92
  93       template<typename _Alloc2,
  94                typename = typename __alloc_traits<_Alloc2>::template
  95                            rebind<value_type>::other>
  96         struct __convertible
  97         { };
  98
  99       template<typename _Alloc2>
 100         struct __convertible<_Alloc2, _Alloc>
 101         {
 102           typedef void* __type;
 103         };
 104
 105       size_type _S_extra()
 106       {
 107         const std::size_t __obj_size = sizeof(value_type);
 108         return (sizeof(size_type) + __obj_size - 1) / __obj_size;
 109       }
 110
 111     public:
 112       debug_allocator() : _M_extra(_S_extra()) { }
 113
 114       template<typename _Alloc2>
 115         debug_allocator(const debug_allocator<_Alloc2>& __a2,
 116                         typename __convertible<_Alloc2>::__type = 0)
 117         : _M_extra(_S_extra()), _M_allocator(__a2._M_allocator)  { }
 118
 119       debug_allocator(const _Alloc& __a)
 120       : _M_extra(_S_extra()), _M_allocator(__a)  { }
 121
 122       _GLIBCXX_NODISCARD pointer
 123       allocate(size_type __n)
 124       {
 125         pointer __res = _M_allocator.allocate(__n + _M_extra);
 126         size_type* __ps = reinterpret_cast<size_type*>(__res);
 127         *__ps = __n;
 128         return __res + _M_extra;
 129       }
 130
 131       _GLIBCXX_NODISCARD pointer
 132       allocate(size_type __n, const void* __hint)
 133       {
 134         pointer __res = _M_allocator.allocate(__n + _M_extra, __hint);
 135         size_type* __ps = reinterpret_cast<size_type*>(__res);
 136         *__ps = __n;
 137         return __res + _M_extra;
 138       }
 139
 140       void
 141       deallocate(pointer __p, size_type __n)
 142       {
 143         using std::__throw_runtime_error;
 144         if (__p)
 145           {
 146             pointer __real_p = __p - _M_extra;
 147             if (*reinterpret_cast<size_type*>(__real_p) != __n)
 148               __throw_runtime_error("debug_allocator::deallocate wrong size");
 149             _M_allocator.deallocate(__real_p, __n + _M_extra);
 150           }
 151         else
 152           __throw_runtime_error("debug_allocator::deallocate null pointer");
 153       }
 154
 155       void
 156       construct(pointer __p, const value_type& __val)
 157       { _Traits::construct(_M_allocator, __p, __val); }
 158
 159 #if __cplusplus >= 201103L
 160       template<typename _Tp, typename... _Args>
 161         void
 162         construct(_Tp* __p, _Args&&... __args)
 163         {
 164           _Traits::construct(_M_allocator, __p,
 165                              std::forward<_Args>(__args)...);
 166         }
 167 #endif
 168
 169       template<typename _Tp>
 170         void
 171         destroy(_Tp* __p)
 172         { _Traits::destroy(_M_allocator, __p); }
 173
 174       size_type
 175       max_size() const throw()
 176       { return _Traits::max_size(_M_allocator) - _M_extra; }
 177
 178       template<typename _Alloc2>
 179         friend bool
 180         operator==(const debug_allocator& __lhs,
 181                    const debug_allocator<_Alloc2>& __rhs) _GLIBCXX_NOTHROW
 182         { return __lhs._M_allocator == debug_allocator(__rhs)._M_allocator; }
 183
 184 #if __cpp_impl_three_way_comparison < 201907L
 185       template<typename _Alloc2>
 186         friend bool
 187         operator!=(const debug_allocator& __lhs,
 188                    const debug_allocator<_Alloc2>& __rhs) _GLIBCXX_NOTHROW
 189         { return !(__lhs == __rhs); }
 190 #endif
 191     };
 192
 193 _GLIBCXX_END_NAMESPACE_VERSION
 194 } // namespace
 195
 196 #endif