libstdc++
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00001 // Safe sequence/iterator base implementation -*- C++ -*- 00002 00003 // Copyright (C) 2003-2013 Free Software Foundation, Inc. 00004 // 00005 // This file is part of the GNU ISO C++ Library. This library is free 00006 // software; you can redistribute it and/or modify it under the 00007 // terms of the GNU General Public License as published by the 00008 // Free Software Foundation; either version 3, or (at your option) 00009 // any later version. 00010 00011 // This library is distributed in the hope that it will be useful, 00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00014 // GNU General Public License for more details. 00015 00016 // Under Section 7 of GPL version 3, you are granted additional 00017 // permissions described in the GCC Runtime Library Exception, version 00018 // 3.1, as published by the Free Software Foundation. 00019 00020 // You should have received a copy of the GNU General Public License and 00021 // a copy of the GCC Runtime Library Exception along with this program; 00022 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00023 // <http://www.gnu.org/licenses/>. 00024 00025 /** @file debug/safe_base.h 00026 * This file is a GNU debug extension to the Standard C++ Library. 00027 */ 00028 00029 #ifndef _GLIBCXX_DEBUG_SAFE_BASE_H 00030 #define _GLIBCXX_DEBUG_SAFE_BASE_H 1 00031 00032 #include <ext/concurrence.h> 00033 00034 namespace __gnu_debug 00035 { 00036 class _Safe_sequence_base; 00037 00038 /** \brief Basic functionality for a @a safe iterator. 00039 * 00040 * The %_Safe_iterator_base base class implements the functionality 00041 * of a safe iterator that is not specific to a particular iterator 00042 * type. It contains a pointer back to the sequence it references 00043 * along with iterator version information and pointers to form a 00044 * doubly-linked list of iterators referenced by the container. 00045 * 00046 * This class must not perform any operations that can throw an 00047 * exception, or the exception guarantees of derived iterators will 00048 * be broken. 00049 */ 00050 class _Safe_iterator_base 00051 { 00052 public: 00053 /** The sequence this iterator references; may be NULL to indicate 00054 a singular iterator. */ 00055 _Safe_sequence_base* _M_sequence; 00056 00057 /** The version number of this iterator. The sentinel value 0 is 00058 * used to indicate an invalidated iterator (i.e., one that is 00059 * singular because of an operation on the container). This 00060 * version number must equal the version number in the sequence 00061 * referenced by _M_sequence for the iterator to be 00062 * non-singular. 00063 */ 00064 unsigned int _M_version; 00065 00066 /** Pointer to the previous iterator in the sequence's list of 00067 iterators. Only valid when _M_sequence != NULL. */ 00068 _Safe_iterator_base* _M_prior; 00069 00070 /** Pointer to the next iterator in the sequence's list of 00071 iterators. Only valid when _M_sequence != NULL. */ 00072 _Safe_iterator_base* _M_next; 00073 00074 protected: 00075 /** Initializes the iterator and makes it singular. */ 00076 _Safe_iterator_base() 00077 : _M_sequence(0), _M_version(0), _M_prior(0), _M_next(0) 00078 { } 00079 00080 /** Initialize the iterator to reference the sequence pointed to 00081 * by @p __seq. @p __constant is true when we are initializing a 00082 * constant iterator, and false if it is a mutable iterator. Note 00083 * that @p __seq may be NULL, in which case the iterator will be 00084 * singular. Otherwise, the iterator will reference @p __seq and 00085 * be nonsingular. 00086 */ 00087 _Safe_iterator_base(const _Safe_sequence_base* __seq, bool __constant) 00088 : _M_sequence(0), _M_version(0), _M_prior(0), _M_next(0) 00089 { this->_M_attach(const_cast<_Safe_sequence_base*>(__seq), __constant); } 00090 00091 /** Initializes the iterator to reference the same sequence that 00092 @p __x does. @p __constant is true if this is a constant 00093 iterator, and false if it is mutable. */ 00094 _Safe_iterator_base(const _Safe_iterator_base& __x, bool __constant) 00095 : _M_sequence(0), _M_version(0), _M_prior(0), _M_next(0) 00096 { this->_M_attach(__x._M_sequence, __constant); } 00097 00098 _Safe_iterator_base& 00099 operator=(const _Safe_iterator_base&); 00100 00101 explicit 00102 _Safe_iterator_base(const _Safe_iterator_base&); 00103 00104 ~_Safe_iterator_base() { this->_M_detach(); } 00105 00106 /** For use in _Safe_iterator. */ 00107 __gnu_cxx::__mutex& _M_get_mutex() throw (); 00108 00109 public: 00110 /** Attaches this iterator to the given sequence, detaching it 00111 * from whatever sequence it was attached to originally. If the 00112 * new sequence is the NULL pointer, the iterator is left 00113 * unattached. 00114 */ 00115 void _M_attach(_Safe_sequence_base* __seq, bool __constant); 00116 00117 /** Likewise, but not thread-safe. */ 00118 void _M_attach_single(_Safe_sequence_base* __seq, bool __constant) throw (); 00119 00120 /** Detach the iterator for whatever sequence it is attached to, 00121 * if any. 00122 */ 00123 void _M_detach(); 00124 00125 /** Likewise, but not thread-safe. */ 00126 void _M_detach_single() throw (); 00127 00128 /** Determines if we are attached to the given sequence. */ 00129 bool _M_attached_to(const _Safe_sequence_base* __seq) const 00130 { return _M_sequence == __seq; } 00131 00132 /** Is this iterator singular? */ 00133 _GLIBCXX_PURE bool _M_singular() const throw (); 00134 00135 /** Can we compare this iterator to the given iterator @p __x? 00136 Returns true if both iterators are nonsingular and reference 00137 the same sequence. */ 00138 _GLIBCXX_PURE bool _M_can_compare(const _Safe_iterator_base& __x) const throw (); 00139 00140 /** Invalidate the iterator, making it singular. */ 00141 void 00142 _M_invalidate() 00143 { _M_version = 0; } 00144 00145 /** Reset all member variables */ 00146 void 00147 _M_reset() throw (); 00148 00149 /** Unlink itself */ 00150 void 00151 _M_unlink() throw () 00152 { 00153 if (_M_prior) 00154 _M_prior->_M_next = _M_next; 00155 if (_M_next) 00156 _M_next->_M_prior = _M_prior; 00157 } 00158 }; 00159 00160 /** 00161 * @brief Base class that supports tracking of iterators that 00162 * reference a sequence. 00163 * 00164 * The %_Safe_sequence_base class provides basic support for 00165 * tracking iterators into a sequence. Sequences that track 00166 * iterators must derived from %_Safe_sequence_base publicly, so 00167 * that safe iterators (which inherit _Safe_iterator_base) can 00168 * attach to them. This class contains two linked lists of 00169 * iterators, one for constant iterators and one for mutable 00170 * iterators, and a version number that allows very fast 00171 * invalidation of all iterators that reference the container. 00172 * 00173 * This class must ensure that no operation on it may throw an 00174 * exception, otherwise @a safe sequences may fail to provide the 00175 * exception-safety guarantees required by the C++ standard. 00176 */ 00177 class _Safe_sequence_base 00178 { 00179 public: 00180 /// The list of mutable iterators that reference this container 00181 _Safe_iterator_base* _M_iterators; 00182 00183 /// The list of constant iterators that reference this container 00184 _Safe_iterator_base* _M_const_iterators; 00185 00186 /// The container version number. This number may never be 0. 00187 mutable unsigned int _M_version; 00188 00189 protected: 00190 // Initialize with a version number of 1 and no iterators 00191 _Safe_sequence_base() 00192 : _M_iterators(0), _M_const_iterators(0), _M_version(1) 00193 { } 00194 00195 /** Notify all iterators that reference this sequence that the 00196 sequence is being destroyed. */ 00197 ~_Safe_sequence_base() 00198 { this->_M_detach_all(); } 00199 00200 /** Detach all iterators, leaving them singular. */ 00201 void 00202 _M_detach_all(); 00203 00204 /** Detach all singular iterators. 00205 * @post for all iterators i attached to this sequence, 00206 * i->_M_version == _M_version. 00207 */ 00208 void 00209 _M_detach_singular(); 00210 00211 /** Revalidates all attached singular iterators. This method may 00212 * be used to validate iterators that were invalidated before 00213 * (but for some reason, such as an exception, need to become 00214 * valid again). 00215 */ 00216 void 00217 _M_revalidate_singular(); 00218 00219 /** Swap this sequence with the given sequence. This operation 00220 * also swaps ownership of the iterators, so that when the 00221 * operation is complete all iterators that originally referenced 00222 * one container now reference the other container. 00223 */ 00224 void 00225 _M_swap(_Safe_sequence_base& __x); 00226 00227 /** For use in _Safe_sequence. */ 00228 __gnu_cxx::__mutex& _M_get_mutex() throw (); 00229 00230 public: 00231 /** Invalidates all iterators. */ 00232 void 00233 _M_invalidate_all() const 00234 { if (++_M_version == 0) _M_version = 1; } 00235 00236 /** Attach an iterator to this sequence. */ 00237 void 00238 _M_attach(_Safe_iterator_base* __it, bool __constant); 00239 00240 /** Likewise but not thread safe. */ 00241 void 00242 _M_attach_single(_Safe_iterator_base* __it, bool __constant) throw (); 00243 00244 /** Detach an iterator from this sequence */ 00245 void 00246 _M_detach(_Safe_iterator_base* __it); 00247 00248 /** Likewise but not thread safe. */ 00249 void 00250 _M_detach_single(_Safe_iterator_base* __it) throw (); 00251 }; 00252 } // namespace __gnu_debug 00253 00254 #endif