--- /dev/null
+// Safe sequence/iterator base implementation -*- C++ -*-
+
+// Copyright (C) 2003, 2004, 2005, 2006, 2009
+// Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+// <http://www.gnu.org/licenses/>.
+
+/** @file debug/safe_base.h
+ * This file is a GNU debug extension to the Standard C++ Library.
+ */
+
+#ifndef _GLIBCXX_DEBUG_SAFE_BASE_H
+#define _GLIBCXX_DEBUG_SAFE_BASE_H 1
+
+#include <ext/concurrence.h>
+
+namespace __gnu_debug
+{
+ class _Safe_sequence_base;
+
+ /** \brief Basic functionality for a "safe" iterator.
+ *
+ * The %_Safe_iterator_base base class implements the functionality
+ * of a safe iterator that is not specific to a particular iterator
+ * type. It contains a pointer back to the sequence it references
+ * along with iterator version information and pointers to form a
+ * doubly-linked list of iterators referenced by the container.
+ *
+ * This class must not perform any operations that can throw an
+ * exception, or the exception guarantees of derived iterators will
+ * be broken.
+ */
+ class _Safe_iterator_base
+ {
+ public:
+ /** The sequence this iterator references; may be NULL to indicate
+ a singular iterator. */
+ _Safe_sequence_base* _M_sequence;
+
+ /** The version number of this iterator. The sentinel value 0 is
+ * used to indicate an invalidated iterator (i.e., one that is
+ * singular because of an operation on the container). This
+ * version number must equal the version number in the sequence
+ * referenced by _M_sequence for the iterator to be
+ * non-singular.
+ */
+ unsigned int _M_version;
+
+ /** Pointer to the previous iterator in the sequence's list of
+ iterators. Only valid when _M_sequence != NULL. */
+ _Safe_iterator_base* _M_prior;
+
+ /** Pointer to the next iterator in the sequence's list of
+ iterators. Only valid when _M_sequence != NULL. */
+ _Safe_iterator_base* _M_next;
+
+ protected:
+ /** Initializes the iterator and makes it singular. */
+ _Safe_iterator_base()
+ : _M_sequence(0), _M_version(0), _M_prior(0), _M_next(0)
+ { }
+
+ /** Initialize the iterator to reference the sequence pointed to
+ * by @p__seq. @p __constant is true when we are initializing a
+ * constant iterator, and false if it is a mutable iterator. Note
+ * that @p __seq may be NULL, in which case the iterator will be
+ * singular. Otherwise, the iterator will reference @p __seq and
+ * be nonsingular.
+ */
+ _Safe_iterator_base(const _Safe_sequence_base* __seq, bool __constant)
+ : _M_sequence(0), _M_version(0), _M_prior(0), _M_next(0)
+ { this->_M_attach(const_cast<_Safe_sequence_base*>(__seq), __constant); }
+
+ /** Initializes the iterator to reference the same sequence that
+ @p __x does. @p __constant is true if this is a constant
+ iterator, and false if it is mutable. */
+ _Safe_iterator_base(const _Safe_iterator_base& __x, bool __constant)
+ : _M_sequence(0), _M_version(0), _M_prior(0), _M_next(0)
+ { this->_M_attach(__x._M_sequence, __constant); }
+
+ _Safe_iterator_base&
+ operator=(const _Safe_iterator_base&);
+
+ explicit
+ _Safe_iterator_base(const _Safe_iterator_base&);
+
+ ~_Safe_iterator_base() { this->_M_detach(); }
+
+ /** For use in _Safe_iterator. */
+ __gnu_cxx::__mutex& _M_get_mutex();
+
+ public:
+ /** Attaches this iterator to the given sequence, detaching it
+ * from whatever sequence it was attached to originally. If the
+ * new sequence is the NULL pointer, the iterator is left
+ * unattached.
+ */
+ void _M_attach(_Safe_sequence_base* __seq, bool __constant);
+
+ /** Likewise, but not thread-safe. */
+ void _M_attach_single(_Safe_sequence_base* __seq, bool __constant);
+
+ /** Detach the iterator for whatever sequence it is attached to,
+ * if any.
+ */
+ void _M_detach();
+
+ /** Likewise, but not thread-safe. */
+ void _M_detach_single();
+
+ /** Determines if we are attached to the given sequence. */
+ bool _M_attached_to(const _Safe_sequence_base* __seq) const
+ { return _M_sequence == __seq; }
+
+ /** Is this iterator singular? */
+ bool _M_singular() const;
+
+ /** Can we compare this iterator to the given iterator @p __x?
+ Returns true if both iterators are nonsingular and reference
+ the same sequence. */
+ bool _M_can_compare(const _Safe_iterator_base& __x) const;
+ };
+
+ /**
+ * @brief Base class that supports tracking of iterators that
+ * reference a sequence.
+ *
+ * The %_Safe_sequence_base class provides basic support for
+ * tracking iterators into a sequence. Sequences that track
+ * iterators must derived from %_Safe_sequence_base publicly, so
+ * that safe iterators (which inherit _Safe_iterator_base) can
+ * attach to them. This class contains two linked lists of
+ * iterators, one for constant iterators and one for mutable
+ * iterators, and a version number that allows very fast
+ * invalidation of all iterators that reference the container.
+ *
+ * This class must ensure that no operation on it may throw an
+ * exception, otherwise "safe" sequences may fail to provide the
+ * exception-safety guarantees required by the C++ standard.
+ */
+ class _Safe_sequence_base
+ {
+ public:
+ /// The list of mutable iterators that reference this container
+ _Safe_iterator_base* _M_iterators;
+
+ /// The list of constant iterators that reference this container
+ _Safe_iterator_base* _M_const_iterators;
+
+ /// The container version number. This number may never be 0.
+ mutable unsigned int _M_version;
+
+ protected:
+ // Initialize with a version number of 1 and no iterators
+ _Safe_sequence_base()
+ : _M_iterators(0), _M_const_iterators(0), _M_version(1)
+ { }
+
+ /** Notify all iterators that reference this sequence that the
+ sequence is being destroyed. */
+ ~_Safe_sequence_base()
+ { this->_M_detach_all(); }
+
+ /** Detach all iterators, leaving them singular. */
+ void
+ _M_detach_all();
+
+ /** Detach all singular iterators.
+ * @post for all iterators i attached to this sequence,
+ * i->_M_version == _M_version.
+ */
+ void
+ _M_detach_singular();
+
+ /** Revalidates all attached singular iterators. This method may
+ * be used to validate iterators that were invalidated before
+ * (but for some reason, such as an exception, need to become
+ * valid again).
+ */
+ void
+ _M_revalidate_singular();
+
+ /** Swap this sequence with the given sequence. This operation
+ * also swaps ownership of the iterators, so that when the
+ * operation is complete all iterators that originally referenced
+ * one container now reference the other container.
+ */
+ void
+ _M_swap(_Safe_sequence_base& __x);
+
+ /** For use in _Safe_sequence. */
+ __gnu_cxx::__mutex& _M_get_mutex();
+
+ public:
+ /** Invalidates all iterators. */
+ void
+ _M_invalidate_all() const
+ { if (++_M_version == 0) _M_version = 1; }
+ };
+} // namespace __gnu_debug
+
+#endif
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