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  1. // Allocators -*- C++ -*-
  2.  
  3. // Copyright (C) 2001-2015 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. #include <bits/functexcept.h>
  47. #include <ext/alloc_traits.h>
  48.  
  49. namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
  50. {
  51. _GLIBCXX_BEGIN_NAMESPACE_VERSION
  52.  
  53.   using std::size_t;
  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 _Alloc2::template rebind<value_type>::other>
  95.         struct __convertible
  96.         { };
  97.  
  98.       template<typename _Alloc2>
  99.         struct __convertible<_Alloc2, _Alloc>
  100.         {
  101.           typedef void* __type;
  102.         };
  103.  
  104.       size_type _S_extra()
  105.       {
  106.         const size_t __obj_size = sizeof(value_type);
  107.         return (sizeof(size_type) + __obj_size - 1) / __obj_size;
  108.       }
  109.  
  110.     public:
  111.       debug_allocator() : _M_extra(_S_extra()) { }
  112.  
  113.       template<typename _Alloc2>
  114.         debug_allocator(const debug_allocator<_Alloc2>& __a2,
  115.                         typename __convertible<_Alloc2>::__type = 0)
  116.         : _M_allocator(__a2._M_allocator), _M_extra(_S_extra()) { }
  117.  
  118.       debug_allocator(const _Alloc& __a)
  119.       : _M_allocator(__a), _M_extra(_S_extra()) { }
  120.  
  121.       pointer
  122.       allocate(size_type __n)
  123.       {
  124.         pointer __res = _M_allocator.allocate(__n + _M_extra);      
  125.         size_type* __ps = reinterpret_cast<size_type*>(__res);
  126.         *__ps = __n;
  127.         return __res + _M_extra;
  128.       }
  129.  
  130.       pointer
  131.       allocate(size_type __n, const void* __hint)
  132.       {
  133.         pointer __res = _M_allocator.allocate(__n + _M_extra, __hint);
  134.         size_type* __ps = reinterpret_cast<size_type*>(__res);
  135.         *__ps = __n;
  136.         return __res + _M_extra;
  137.       }
  138.  
  139.       void
  140.       deallocate(pointer __p, size_type __n)
  141.       {
  142.         using std::__throw_runtime_error;
  143.         if (__p)
  144.           {
  145.             pointer __real_p = __p - _M_extra;
  146.             if (*reinterpret_cast<size_type*>(__real_p) != __n)
  147.               __throw_runtime_error("debug_allocator::deallocate wrong size");
  148.             _M_allocator.deallocate(__real_p, __n + _M_extra);
  149.           }
  150.         else
  151.           __throw_runtime_error("debug_allocator::deallocate null pointer");
  152.       }
  153.  
  154.       void
  155.       construct(pointer __p, const value_type& __val)
  156.       { _Traits::construct(_M_allocator, __p, __val); }
  157.  
  158. #if __cplusplus >= 201103L
  159.       template<typename _Tp, typename... _Args>
  160.         void
  161.         construct(_Tp* __p, _Args&&... __args)
  162.         {
  163.           _Traits::construct(_M_allocator, __p,
  164.                              std::forward<_Args>(__args)...);
  165.         }
  166. #endif
  167.  
  168.       template<typename _Tp>
  169.         void
  170.         destroy(_Tp* __p)
  171.         { _Traits::destroy(_M_allocator, __p); }
  172.  
  173.       size_type
  174.       max_size() const throw()
  175.       { return _Traits::max_size(_M_allocator) - _M_extra; }
  176.  
  177.       friend bool
  178.       operator==(const debug_allocator& __lhs, const debug_allocator& __rhs)
  179.       { return __lhs._M_allocator == __rhs._M_allocator; }
  180.     };
  181.  
  182.   template<typename _Alloc>
  183.     inline bool
  184.     operator!=(const debug_allocator<_Alloc>& __lhs,
  185.                const debug_allocator<_Alloc>& __rhs)
  186.     { return !(__lhs == __rhs); }
  187.  
  188. _GLIBCXX_END_NAMESPACE_VERSION
  189. } // namespace
  190.  
  191. #endif
  192.