1// Safe sequence/iterator base implementation -*- C++ -*- 2 3// Copyright (C) 2003, 2004 4// Free Software Foundation, Inc. 5// 6// This file is part of the GNU ISO C++ Library. This library is free 7// software; you can redistribute it and/or modify it under the 8// terms of the GNU General Public License as published by the 9// Free Software Foundation; either version 2, or (at your option) 10// any later version. 11 12// This library is distributed in the hope that it will be useful, 13// but WITHOUT ANY WARRANTY; without even the implied warranty of 14// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15// GNU General Public License for more details. 16 17// You should have received a copy of the GNU General Public License along 18// with this library; see the file COPYING. If not, write to the Free 19// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 20// USA. 21 22// As a special exception, you may use this file as part of a free software 23// library without restriction. Specifically, if other files instantiate 24// templates or use macros or inline functions from this file, or you compile 25// this file and link it with other files to produce an executable, this 26// file does not by itself cause the resulting executable to be covered by 27// the GNU General Public License. This exception does not however 28// invalidate any other reasons why the executable file might be covered by 29// the GNU General Public License. 30 31#ifndef _GLIBCXX_DEBUG_SAFE_BASE_H 32#define _GLIBCXX_DEBUG_SAFE_BASE_H 1 33 34namespace __gnu_debug 35{ 36 class _Safe_sequence_base; 37 38 /** \brief Basic functionality for 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 */ 50 class _Safe_iterator_base 51 { 52 public: 53 /** The sequence this iterator references; may be NULL to indicate 54 a singular iterator. */ 55 _Safe_sequence_base* _M_sequence; 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. */ 68 _Safe_iterator_base* _M_prior; 69 70 /** Pointer to the next iterator in the sequence's list of 71 iterators. Only valid when _M_sequence != NULL. */ 72 _Safe_iterator_base* _M_next; 73 74 protected: 75 /** Initializes the iterator and makes it singular. */ 76 _Safe_iterator_base() 77 : _M_sequence(0), _M_version(0), _M_prior(0), _M_next(0) 78 { } 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& 99 operator=(const _Safe_iterator_base&); 100 101 explicit 102 _Safe_iterator_base(const _Safe_iterator_base&); 103 104 ~_Safe_iterator_base() { this->_M_detach(); } 105 106 public: 107 /** Attaches this iterator to the given sequence, detaching it 108 * from whatever sequence it was attached to originally. If the 109 * new sequence is the NULL pointer, the iterator is left 110 * unattached. 111 */ 112 void _M_attach(_Safe_sequence_base* __seq, bool __constant); 113 114 /** Detach the iterator for whatever sequence it is attached to, 115 * if any. 116 */ 117 void _M_detach(); 118 119 /** Determines if we are attached to the given sequence. */ 120 bool _M_attached_to(const _Safe_sequence_base* __seq) const 121 { return _M_sequence == __seq; } 122 123 /** Is this iterator singular? */ 124 bool _M_singular() const; 125 126 /** Can we compare this iterator to the given iterator @p __x? 127 Returns true if both iterators are nonsingular and reference 128 the same sequence. */ 129 bool _M_can_compare(const _Safe_iterator_base& __x) const; 130 }; 131 132 /** 133 * @brief Base class that supports tracking of iterators that 134 * reference a sequence. 135 * 136 * The %_Safe_sequence_base class provides basic support for 137 * tracking iterators into a sequence. Sequences that track 138 * iterators must derived from %_Safe_sequence_base publicly, so 139 * that safe iterators (which inherit _Safe_iterator_base) can 140 * attach to them. This class contains two linked lists of 141 * iterators, one for constant iterators and one for mutable 142 * iterators, and a version number that allows very fast 143 * invalidation of all iterators that reference the container. 144 * 145 * This class must ensure that no operation on it may throw an 146 * exception, otherwise "safe" sequences may fail to provide the 147 * exception-safety guarantees required by the C++ standard. 148 */ 149 class _Safe_sequence_base 150 { 151 public: 152 /// The list of mutable iterators that reference this container 153 _Safe_iterator_base* _M_iterators; 154 155 /// The list of constant iterators that reference this container 156 _Safe_iterator_base* _M_const_iterators; 157 158 /// The container version number. This number may never be 0. 159 mutable unsigned int _M_version; 160 161 protected: 162 // Initialize with a version number of 1 and no iterators 163 _Safe_sequence_base() 164 : _M_iterators(0), _M_const_iterators(0), _M_version(1) 165 { } 166 167 /** Notify all iterators that reference this sequence that the 168 sequence is being destroyed. */ 169 ~_Safe_sequence_base() 170 { this->_M_detach_all(); } 171 172 /** Detach all iterators, leaving them singular. */ 173 void 174 _M_detach_all(); 175 176 /** Detach all singular iterators. 177 * @post for all iterators i attached to this sequence, 178 * i->_M_version == _M_version. 179 */ 180 void 181 _M_detach_singular(); 182 183 /** Revalidates all attached singular iterators. This method may 184 * be used to validate iterators that were invalidated before 185 * (but for some reasion, such as an exception, need to become 186 * valid again). 187 */ 188 void 189 _M_revalidate_singular(); 190 191 /** Swap this sequence with the given sequence. This operation 192 * also swaps ownership of the iterators, so that when the 193 * operation is complete all iterators that originally referenced 194 * one container now reference the other container. 195 */ 196 void 197 _M_swap(_Safe_sequence_base& __x); 198 199 public: 200 /** Invalidates all iterators. */ 201 void 202 _M_invalidate_all() const 203 { if (++_M_version == 0) _M_version = 1; } 204 }; 205} // namespace __gnu_debug 206 207#endif 208