mingw/lib/gcc/mingw32/4.3.3/include/c++/debug/safe_base.h

   1 // Safe sequence/iterator base implementation  -*- C++ -*-
   2
   3 // Copyright (C) 2003, 2004, 2005, 2006
   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 /** @file debug/safe_base.h
  32  *  This file is a GNU debug extension to the Standard C++ Library.
  33  */
  34
  35 #ifndef _GLIBCXX_DEBUG_SAFE_BASE_H
  36 #define _GLIBCXX_DEBUG_SAFE_BASE_H 1
  37
  38 #include <ext/concurrence.h>
  39
  40 namespace __gnu_debug
  41 {
  42   class _Safe_sequence_base;
  43
  44   /** \brief Basic functionality for a "safe" iterator.
  45    *
  46    *  The %_Safe_iterator_base base class implements the functionality
  47    *  of a safe iterator that is not specific to a particular iterator
  48    *  type. It contains a pointer back to the sequence it references
  49    *  along with iterator version information and pointers to form a
  50    *  doubly-linked list of iterators referenced by the container.
  51    *
  52    *  This class must not perform any operations that can throw an
  53    *  exception, or the exception guarantees of derived iterators will
  54    *  be broken.
  55    */
  56   class _Safe_iterator_base
  57   {
  58   public:
  59     /** The sequence this iterator references; may be NULL to indicate
  60         a singular iterator. */
  61     _Safe_sequence_base* _M_sequence;
  62
  63     /** The version number of this iterator. The sentinel value 0 is
  64      *  used to indicate an invalidated iterator (i.e., one that is
  65      *  singular because of an operation on the container). This
  66      *  version number must equal the version number in the sequence
  67      *  referenced by _M_sequence for the iterator to be
  68      *  non-singular.
  69      */
  70     unsigned int         _M_version;
  71
  72     /** Pointer to the previous iterator in the sequence's list of
  73         iterators. Only valid when _M_sequence != NULL. */
  74     _Safe_iterator_base* _M_prior;
  75
  76     /** Pointer to the next iterator in the sequence's list of
  77         iterators. Only valid when _M_sequence != NULL. */
  78     _Safe_iterator_base* _M_next;
  79
  80   protected:
  81     /** Initializes the iterator and makes it singular. */
  82     _Safe_iterator_base()
  83     : _M_sequence(0), _M_version(0), _M_prior(0), _M_next(0)
  84     { }
  85
  86     /** Initialize the iterator to reference the sequence pointed to
  87      *  by @p__seq. @p __constant is true when we are initializing a
  88      *  constant iterator, and false if it is a mutable iterator. Note
  89      *  that @p __seq may be NULL, in which case the iterator will be
  90      *  singular. Otherwise, the iterator will reference @p __seq and
  91      *  be nonsingular.
  92      */
  93     _Safe_iterator_base(const _Safe_sequence_base* __seq, bool __constant)
  94     : _M_sequence(0), _M_version(0), _M_prior(0), _M_next(0)
  95     { this->_M_attach(const_cast<_Safe_sequence_base*>(__seq), __constant); }
  96
  97     /** Initializes the iterator to reference the same sequence that
  98         @p __x does. @p __constant is true if this is a constant
  99         iterator, and false if it is mutable. */
 100     _Safe_iterator_base(const _Safe_iterator_base& __x, bool __constant)
 101     : _M_sequence(0), _M_version(0), _M_prior(0), _M_next(0)
 102     { this->_M_attach(__x._M_sequence, __constant); }
 103
 104     _Safe_iterator_base&
 105     operator=(const _Safe_iterator_base&);
 106
 107     explicit
 108     _Safe_iterator_base(const _Safe_iterator_base&);
 109
 110     ~_Safe_iterator_base() { this->_M_detach(); }
 111
 112     /** For use in _Safe_iterator. */
 113     __gnu_cxx::__mutex& _M_get_mutex();
 114
 115   public:
 116     /** Attaches this iterator to the given sequence, detaching it
 117      *  from whatever sequence it was attached to originally. If the
 118      *  new sequence is the NULL pointer, the iterator is left
 119      *  unattached.
 120      */
 121     void _M_attach(_Safe_sequence_base* __seq, bool __constant);
 122
 123     /** Likewise, but not thread-safe. */
 124     void _M_attach_single(_Safe_sequence_base* __seq, bool __constant);
 125
 126     /** Detach the iterator for whatever sequence it is attached to,
 127      *  if any.
 128     */
 129     void _M_detach();
 130
 131     /** Likewise, but not thread-safe. */
 132     void _M_detach_single();
 133
 134     /** Determines if we are attached to the given sequence. */
 135     bool _M_attached_to(const _Safe_sequence_base* __seq) const
 136     { return _M_sequence == __seq; }
 137
 138     /** Is this iterator singular? */
 139     bool _M_singular() const;
 140
 141     /** Can we compare this iterator to the given iterator @p __x?
 142         Returns true if both iterators are nonsingular and reference
 143         the same sequence. */
 144     bool _M_can_compare(const _Safe_iterator_base& __x) const;
 145   };
 146
 147   /**
 148    * @brief Base class that supports tracking of iterators that
 149    * reference a sequence.
 150    *
 151    * The %_Safe_sequence_base class provides basic support for
 152    * tracking iterators into a sequence. Sequences that track
 153    * iterators must derived from %_Safe_sequence_base publicly, so
 154    * that safe iterators (which inherit _Safe_iterator_base) can
 155    * attach to them. This class contains two linked lists of
 156    * iterators, one for constant iterators and one for mutable
 157    * iterators, and a version number that allows very fast
 158    * invalidation of all iterators that reference the container.
 159    *
 160    * This class must ensure that no operation on it may throw an
 161    * exception, otherwise "safe" sequences may fail to provide the
 162    * exception-safety guarantees required by the C++ standard.
 163    */
 164   class _Safe_sequence_base
 165   {
 166   public:
 167     /// The list of mutable iterators that reference this container
 168     _Safe_iterator_base* _M_iterators;
 169
 170     /// The list of constant iterators that reference this container
 171     _Safe_iterator_base* _M_const_iterators;
 172
 173     /// The container version number. This number may never be 0.
 174     mutable unsigned int _M_version;
 175
 176   protected:
 177     // Initialize with a version number of 1 and no iterators
 178     _Safe_sequence_base()
 179     : _M_iterators(0), _M_const_iterators(0), _M_version(1)
 180     { }
 181
 182     /** Notify all iterators that reference this sequence that the
 183         sequence is being destroyed. */
 184     ~_Safe_sequence_base()
 185     { this->_M_detach_all(); }
 186
 187     /** Detach all iterators, leaving them singular. */
 188     void
 189     _M_detach_all();
 190
 191     /** Detach all singular iterators.
 192      *  @post for all iterators i attached to this sequence,
 193      *   i->_M_version == _M_version.
 194      */
 195     void
 196     _M_detach_singular();
 197
 198     /** Revalidates all attached singular iterators.  This method may
 199      *  be used to validate iterators that were invalidated before
 200      *  (but for some reason, such as an exception, need to become
 201      *  valid again).
 202      */
 203     void
 204     _M_revalidate_singular();
 205
 206     /** Swap this sequence with the given sequence. This operation
 207      *  also swaps ownership of the iterators, so that when the
 208      *  operation is complete all iterators that originally referenced
 209      *  one container now reference the other container.
 210      */
 211     void
 212     _M_swap(_Safe_sequence_base& __x);
 213
 214     /** For use in _Safe_sequence. */
 215     __gnu_cxx::__mutex& _M_get_mutex();
 216
 217   public:
 218     /** Invalidates all iterators. */
 219     void
 220     _M_invalidate_all() const
 221     { if (++_M_version == 0) _M_version = 1; }
 222   };
 223 } // namespace __gnu_debug
 224
 225 #endif