1 // Safe container/iterator base implementation -*- C++ -*-
2
3 // Copyright (C) 2011-2023 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 /** @file debug/safe_unordered_base.h
26 * This file is a GNU debug extension to the Standard C++ Library.
27 */
28
29 #ifndef _GLIBCXX_DEBUG_SAFE_UNORDERED_BASE_H
30 #define _GLIBCXX_DEBUG_SAFE_UNORDERED_BASE_H 1
31
32 #include <debug/safe_base.h>
33
34 namespace __gnu_debug
35 {
36 class _Safe_unordered_container_base;
37
38 /** \brief Basic functionality for a @a safe iterator.
39 *
40 * The %_Safe_local_iterator_base base class implements the functionality
41 * of a safe local iterator that is not specific to a particular iterator
42 * type. It contains a pointer back to the container it references
43 * along with iterator version information and pointers to form a
44 * doubly-linked list of local iterators referenced by the container.
45 *
46 * This class must not perform any operations that can throw an
47 * exception, or the exception guarantees of derived iterators will
48 * be broken.
49 */
50 class _Safe_local_iterator_base : public _Safe_iterator_base
51 {
52 protected:
53 /** Initializes the iterator and makes it singular. */
54 _Safe_local_iterator_base()
55 { }
56
57 /** Initialize the iterator to reference the container pointed to
58 * by @p __seq. @p __constant is true when we are initializing a
59 * constant local iterator, and false if it is a mutable local iterator.
60 * Note that @p __seq may be NULL, in which case the iterator will be
61 * singular. Otherwise, the iterator will reference @p __seq and
62 * be nonsingular.
63 */
64 _Safe_local_iterator_base(const _Safe_sequence_base* __seq, bool __constant)
65 { this->_M_attach(const_cast<_Safe_sequence_base*>(__seq), __constant); }
66
67 /** Initializes the iterator to reference the same container that
68 @p __x does. @p __constant is true if this is a constant
69 iterator, and false if it is mutable. */
70 _Safe_local_iterator_base(const _Safe_local_iterator_base& __x,
71 bool __constant)
72 { this->_M_attach(__x._M_sequence, __constant); }
73
74 ~_Safe_local_iterator_base() { this->_M_detach(); }
75
76 _Safe_unordered_container_base*
77 _M_get_container() const noexcept;
78
79 /** Attaches this iterator to the given container, detaching it
80 * from whatever container it was attached to originally. If the
81 * new container is the NULL pointer, the iterator is left
82 * unattached.
83 */
84 void
85 _M_attach(_Safe_sequence_base* __seq, bool __constant);
86
87 /** Likewise, but not thread-safe. */
88 void
89 _M_attach_single(_Safe_sequence_base* __seq, bool __constant) throw ();
90
91 /** Detach the iterator for whatever container it is attached to,
92 * if any.
93 */
94 void
95 _M_detach();
96
97 /** Likewise, but not thread-safe. */
98 void
99 _M_detach_single() throw ();
100 };
101
102 /**
103 * @brief Base class that supports tracking of local iterators that
104 * reference an unordered container.
105 *
106 * The %_Safe_unordered_container_base class provides basic support for
107 * tracking iterators into an unordered container. Containers that track
108 * iterators must derived from %_Safe_unordered_container_base publicly, so
109 * that safe iterators (which inherit _Safe_iterator_base) can
110 * attach to them. This class contains four linked lists of
111 * iterators, one for constant iterators, one for mutable
112 * iterators, one for constant local iterators, one for mutable local
113 * iterators and a version number that allows very fast
114 * invalidation of all iterators that reference the container.
115 *
116 * This class must ensure that no operation on it may throw an
117 * exception, otherwise @a safe containers may fail to provide the
118 * exception-safety guarantees required by the C++ standard.
119 */
120 class _Safe_unordered_container_base : public _Safe_sequence_base
121 {
122 friend class _Safe_local_iterator_base;
123 typedef _Safe_sequence_base _Base;
124
125 public:
126 /// The list of mutable local iterators that reference this container
127 _Safe_iterator_base* _M_local_iterators;
128
129 /// The list of constant local iterators that reference this container
130 _Safe_iterator_base* _M_const_local_iterators;
131
132 protected:
133 // Initialize with a version number of 1 and no iterators
134 _Safe_unordered_container_base() noexcept
135 : _M_local_iterators(nullptr), _M_const_local_iterators(nullptr)
136 { }
137
138 // Copy constructor does not copy iterators.
139 _Safe_unordered_container_base(const _Safe_unordered_container_base&)
140 noexcept
141 : _Safe_unordered_container_base() { }
142
143 // When moved unordered containers iterators are swapped.
144 _Safe_unordered_container_base(_Safe_unordered_container_base&& __x)
145 noexcept
146 : _Safe_unordered_container_base()
147 { this->_M_swap(__x); }
148
149 /** Notify all iterators that reference this container that the
150 container is being destroyed. */
151 ~_Safe_unordered_container_base() noexcept
152 { this->_M_detach_all(); }
153
154 /** Detach all iterators, leaving them singular. */
155 void
156 _M_detach_all();
157
158 /** Swap this container with the given container. This operation
159 * also swaps ownership of the iterators, so that when the
160 * operation is complete all iterators that originally referenced
161 * one container now reference the other container.
162 */
163 void
164 _M_swap(_Safe_unordered_container_base& __x) noexcept;
165
166 private:
167 /** Attach an iterator to this container. */
168 void
169 _M_attach_local(_Safe_iterator_base* __it, bool __constant);
170
171 /** Likewise but not thread safe. */
172 void
173 _M_attach_local_single(_Safe_iterator_base* __it, bool __constant) throw ();
174
175 /** Detach an iterator from this container */
176 void
177 _M_detach_local(_Safe_iterator_base* __it);
178
179 /** Likewise but not thread safe. */
180 void
181 _M_detach_local_single(_Safe_iterator_base* __it) throw ();
182 };
183 } // namespace __gnu_debug
184
185 #endif