libstdc++
debug_allocator.h
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1 // Allocators -*- C++ -*-
2 
3 // Copyright (C) 2001-2024 Free Software Foundation, Inc.
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.
19 
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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 <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>
63  {
64  template<typename> friend class debug_allocator;
65 
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
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>
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
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.