libstdc++
safe_base.h
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1// Safe sequence/iterator base implementation -*- C++ -*-
2
3// Copyright (C) 2003-2016 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_base.h
26 * This file is a GNU debug extension to the Standard C++ Library.
27 */
28
29#ifndef _GLIBCXX_DEBUG_SAFE_BASE_H
30#define _GLIBCXX_DEBUG_SAFE_BASE_H 1
31
32#include <ext/concurrence.h>
33
34namespace __gnu_debug
35{
36 class _Safe_sequence_base;
37
38 /** \brief Basic functionality for a @a safe iterator.
39 *
40 * The %_Safe_iterator_base base class implements the functionality
41 * of a safe iterator that is not specific to a particular iterator
42 * type. It contains a pointer back to the sequence it references
43 * along with iterator version information and pointers to form a
44 * doubly-linked list of 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 */
51 {
52 public:
53 /** The sequence this iterator references; may be NULL to indicate
54 a singular iterator. */
56
57 /** The version number of this iterator. The sentinel value 0 is
58 * used to indicate an invalidated iterator (i.e., one that is
59 * singular because of an operation on the container). This
60 * version number must equal the version number in the sequence
61 * referenced by _M_sequence for the iterator to be
62 * non-singular.
63 */
64 unsigned int _M_version;
65
66 /** Pointer to the previous iterator in the sequence's list of
67 iterators. Only valid when _M_sequence != NULL. */
69
70 /** Pointer to the next iterator in the sequence's list of
71 iterators. Only valid when _M_sequence != NULL. */
73
74 protected:
75 /** Initializes the iterator and makes it singular. */
79
80 /** Initialize the iterator to reference the sequence pointed to
81 * by @p __seq. @p __constant is true when we are initializing a
82 * constant iterator, and false if it is a mutable iterator. Note
83 * that @p __seq may be NULL, in which case the iterator will be
84 * singular. Otherwise, the iterator will reference @p __seq and
85 * be nonsingular.
86 */
87 _Safe_iterator_base(const _Safe_sequence_base* __seq, bool __constant)
88 : _M_sequence(0), _M_version(0), _M_prior(0), _M_next(0)
89 { this->_M_attach(const_cast<_Safe_sequence_base*>(__seq), __constant); }
90
91 /** Initializes the iterator to reference the same sequence that
92 @p __x does. @p __constant is true if this is a constant
93 iterator, and false if it is mutable. */
94 _Safe_iterator_base(const _Safe_iterator_base& __x, bool __constant)
95 : _M_sequence(0), _M_version(0), _M_prior(0), _M_next(0)
96 { this->_M_attach(__x._M_sequence, __constant); }
97
98 ~_Safe_iterator_base() { this->_M_detach(); }
99
100 /** For use in _Safe_iterator. */
101 __gnu_cxx::__mutex&
102 _M_get_mutex() throw ();
103
104 public:
105 /** Attaches this iterator to the given sequence, detaching it
106 * from whatever sequence it was attached to originally. If the
107 * new sequence is the NULL pointer, the iterator is left
108 * unattached.
109 */
110 void
111 _M_attach(_Safe_sequence_base* __seq, bool __constant);
112
113 /** Likewise, but not thread-safe. */
114 void
115 _M_attach_single(_Safe_sequence_base* __seq, bool __constant) throw ();
116
117 /** Detach the iterator for whatever sequence it is attached to,
118 * if any.
119 */
120 void
122
123 /** Likewise, but not thread-safe. */
124 void
126
127 /** Determines if we are attached to the given sequence. */
128 bool
130 { return _M_sequence == __seq; }
131
132 /** Is this iterator singular? */
133 _GLIBCXX_PURE bool
134 _M_singular() const throw ();
135
136 /** Can we compare this iterator to the given iterator @p __x?
137 Returns true if both iterators are nonsingular and reference
138 the same sequence. */
139 _GLIBCXX_PURE bool
140 _M_can_compare(const _Safe_iterator_base& __x) const throw ();
141
142 /** Invalidate the iterator, making it singular. */
143 void
145 { _M_version = 0; }
146
147 /** Reset all member variables */
148 void
149 _M_reset() throw ();
150
151 /** Unlink itself */
152 void
153 _M_unlink() throw ()
154 {
155 if (_M_prior)
157 if (_M_next)
159 }
160 };
161
162 /** Iterators that derive from _Safe_iterator_base can be determined singular
163 * or non-singular.
164 **/
165 inline bool
166 __check_singular_aux(const _Safe_iterator_base* __x)
167 { return __x->_M_singular(); }
168
169 /**
170 * @brief Base class that supports tracking of iterators that
171 * reference a sequence.
172 *
173 * The %_Safe_sequence_base class provides basic support for
174 * tracking iterators into a sequence. Sequences that track
175 * iterators must derived from %_Safe_sequence_base publicly, so
176 * that safe iterators (which inherit _Safe_iterator_base) can
177 * attach to them. This class contains two linked lists of
178 * iterators, one for constant iterators and one for mutable
179 * iterators, and a version number that allows very fast
180 * invalidation of all iterators that reference the container.
181 *
182 * This class must ensure that no operation on it may throw an
183 * exception, otherwise @a safe sequences may fail to provide the
184 * exception-safety guarantees required by the C++ standard.
185 */
187 {
188 public:
189 /// The list of mutable iterators that reference this container
191
192 /// The list of constant iterators that reference this container
194
195 /// The container version number. This number may never be 0.
196 mutable unsigned int _M_version;
197
198 protected:
199 // Initialize with a version number of 1 and no iterators
200 _Safe_sequence_base() _GLIBCXX_NOEXCEPT
202 { }
203
204#if __cplusplus >= 201103L
206 : _Safe_sequence_base() { }
207#endif
208
209 /** Notify all iterators that reference this sequence that the
210 sequence is being destroyed. */
213
214 /** Detach all iterators, leaving them singular. */
215 void
217
218 /** Detach all singular iterators.
219 * @post for all iterators i attached to this sequence,
220 * i->_M_version == _M_version.
221 */
222 void
224
225 /** Revalidates all attached singular iterators. This method may
226 * be used to validate iterators that were invalidated before
227 * (but for some reason, such as an exception, need to become
228 * valid again).
229 */
230 void
232
233 /** Swap this sequence with the given sequence. This operation
234 * also swaps ownership of the iterators, so that when the
235 * operation is complete all iterators that originally referenced
236 * one container now reference the other container.
237 */
238 void
239 _M_swap(_Safe_sequence_base& __x) _GLIBCXX_USE_NOEXCEPT;
240
241 /** For use in _Safe_sequence. */
242 __gnu_cxx::__mutex&
243 _M_get_mutex() throw ();
244
245 public:
246 /** Invalidates all iterators. */
247 void
249 { if (++_M_version == 0) _M_version = 1; }
250
251 /** Attach an iterator to this sequence. */
252 void
253 _M_attach(_Safe_iterator_base* __it, bool __constant);
254
255 /** Likewise but not thread safe. */
256 void
257 _M_attach_single(_Safe_iterator_base* __it, bool __constant) throw ();
258
259 /** Detach an iterator from this sequence */
260 void
262
263 /** Likewise but not thread safe. */
264 void
266 };
267} // namespace __gnu_debug
268
269#endif
GNU debug classes for public use.
Basic functionality for a safe iterator.
Definition safe_base.h:51
_Safe_iterator_base(const _Safe_iterator_base &__x, bool __constant)
Definition safe_base.h:94
_Safe_sequence_base * _M_sequence
Definition safe_base.h:55
__gnu_cxx::__mutex & _M_get_mutex()
void _M_attach_single(_Safe_sequence_base *__seq, bool __constant)
void _M_attach(_Safe_sequence_base *__seq, bool __constant)
bool _M_attached_to(const _Safe_sequence_base *__seq) const
Definition safe_base.h:129
_Safe_iterator_base(const _Safe_sequence_base *__seq, bool __constant)
Definition safe_base.h:87
_Safe_iterator_base * _M_prior
Definition safe_base.h:68
bool _M_can_compare(const _Safe_iterator_base &__x) const
_Safe_iterator_base * _M_next
Definition safe_base.h:72
Base class that supports tracking of iterators that reference a sequence.
Definition safe_base.h:187
void _M_detach(_Safe_iterator_base *__it)
void _M_swap(_Safe_sequence_base &__x) noexcept
_Safe_iterator_base * _M_const_iterators
The list of constant iterators that reference this container.
Definition safe_base.h:193
__gnu_cxx::__mutex & _M_get_mutex()
_Safe_iterator_base * _M_iterators
The list of mutable iterators that reference this container.
Definition safe_base.h:190
void _M_attach(_Safe_iterator_base *__it, bool __constant)
void _M_detach_single(_Safe_iterator_base *__it)
void _M_attach_single(_Safe_iterator_base *__it, bool __constant)
unsigned int _M_version
The container version number. This number may never be 0.
Definition safe_base.h:196