libstdc++
debug_allocator.h
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1 // Allocators -*- C++ -*-
2 
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4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
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10 
11 // This library is distributed in the hope that it will be useful,
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15 
16 // Under Section 7 of GPL version 3, you are granted additional
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18 // 3.1, as published by the Free Software Foundation.
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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  /**
54  * @brief A meta-allocator with debugging bits.
55  * @ingroup allocators
56  *
57  * This is precisely the allocator defined in the C++03 Standard.
58  */
59  template<typename _Alloc>
61  {
62  template<typename> friend class debug_allocator;
63 
65 
66  public:
67  typedef typename _Traits::size_type size_type;
68  typedef typename _Traits::difference_type difference_type;
69  typedef typename _Traits::pointer pointer;
70  typedef typename _Traits::const_pointer const_pointer;
71  typedef typename _Traits::reference reference;
72  typedef typename _Traits::const_reference const_reference;
73  typedef typename _Traits::value_type value_type;
74 
75  template<typename _Up>
76  class rebind
77  {
78  typedef typename _Traits::template rebind<_Up>::other __other;
79 
80  public:
81  typedef debug_allocator<__other> other;
82  };
83 
84  private:
85  // _M_extra is the number of objects that correspond to the
86  // extra space where debug information is stored.
87  size_type _M_extra;
88 
89  _Alloc _M_allocator;
90 
91  template<typename _Alloc2,
92  typename = typename __alloc_traits<_Alloc2>::template
94  struct __convertible
95  { };
96 
97  template<typename _Alloc2>
98  struct __convertible<_Alloc2, _Alloc>
99  {
100  typedef void* __type;
101  };
102 
103  size_type _S_extra()
104  {
105  const std::size_t __obj_size = sizeof(value_type);
106  return (sizeof(size_type) + __obj_size - 1) / __obj_size;
107  }
108 
109  public:
110  debug_allocator() : _M_extra(_S_extra()) { }
111 
112  template<typename _Alloc2>
114  typename __convertible<_Alloc2>::__type = 0)
115  : _M_extra(_S_extra()), _M_allocator(__a2._M_allocator) { }
116 
117  debug_allocator(const _Alloc& __a)
118  : _M_extra(_S_extra()), _M_allocator(__a) { }
119 
120  _GLIBCXX_NODISCARD pointer
121  allocate(size_type __n)
122  {
123  pointer __res = _M_allocator.allocate(__n + _M_extra);
124  size_type* __ps = reinterpret_cast<size_type*>(__res);
125  *__ps = __n;
126  return __res + _M_extra;
127  }
128 
129  _GLIBCXX_NODISCARD pointer
130  allocate(size_type __n, const void* __hint)
131  {
132  pointer __res = _M_allocator.allocate(__n + _M_extra, __hint);
133  size_type* __ps = reinterpret_cast<size_type*>(__res);
134  *__ps = __n;
135  return __res + _M_extra;
136  }
137 
138  void
139  deallocate(pointer __p, size_type __n)
140  {
141  using std::__throw_runtime_error;
142  if (__p)
143  {
144  pointer __real_p = __p - _M_extra;
145  if (*reinterpret_cast<size_type*>(__real_p) != __n)
146  __throw_runtime_error("debug_allocator::deallocate wrong size");
147  _M_allocator.deallocate(__real_p, __n + _M_extra);
148  }
149  else
150  __throw_runtime_error("debug_allocator::deallocate null pointer");
151  }
152 
153  void
154  construct(pointer __p, const value_type& __val)
155  { _Traits::construct(_M_allocator, __p, __val); }
156 
157 #if __cplusplus >= 201103L
158  template<typename _Tp, typename... _Args>
159  void
160  construct(_Tp* __p, _Args&&... __args)
161  {
162  _Traits::construct(_M_allocator, __p,
163  std::forward<_Args>(__args)...);
164  }
165 #endif
166 
167  template<typename _Tp>
168  void
169  destroy(_Tp* __p)
170  { _Traits::destroy(_M_allocator, __p); }
171 
172  size_type
173  max_size() const throw()
174  { return _Traits::max_size(_M_allocator) - _M_extra; }
175 
176  template<typename _Alloc2>
177  friend bool
178  operator==(const debug_allocator& __lhs,
179  const debug_allocator<_Alloc2>& __rhs) _GLIBCXX_NOTHROW
180  { return __lhs._M_allocator == debug_allocator(__rhs)._M_allocator; }
181 
182 #if __cpp_impl_three_way_comparison < 201907L
183  template<typename _Alloc2>
184  friend bool
185  operator!=(const debug_allocator& __lhs,
186  const debug_allocator<_Alloc2>& __rhs) _GLIBCXX_NOTHROW
187  { return !(__lhs == __rhs); }
188 #endif
189  };
190 
191 _GLIBCXX_END_NAMESPACE_VERSION
192 } // namespace
193 
194 #endif
GNU extensions for public use.
Uniform interface to C++98 and C++11 allocators.
static constexpr size_type max_size(const _Alloc &__a) noexcept
The maximum supported allocation size.
A meta-allocator with debugging bits.