279 lines
9.1 KiB
C++
279 lines
9.1 KiB
C++
// Safe sequence/iterator base implementation -*- C++ -*-
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// Copyright (C) 2003-2021 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/** @file debug/safe_base.h
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* This file is a GNU debug extension to the Standard C++ Library.
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*/
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#ifndef _GLIBCXX_DEBUG_SAFE_BASE_H
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#define _GLIBCXX_DEBUG_SAFE_BASE_H 1
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#include <ext/concurrence.h>
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namespace __gnu_debug
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{
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class _Safe_sequence_base;
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/** \brief Basic functionality for a @a safe iterator.
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*
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* The %_Safe_iterator_base base class implements the functionality
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* of a safe iterator that is not specific to a particular iterator
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* type. It contains a pointer back to the sequence it references
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* along with iterator version information and pointers to form a
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* doubly-linked list of iterators referenced by the container.
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*
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* This class must not perform any operations that can throw an
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* exception, or the exception guarantees of derived iterators will
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* be broken.
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*/
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class _Safe_iterator_base
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{
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friend class _Safe_sequence_base;
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public:
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/** The sequence this iterator references; may be NULL to indicate
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a singular iterator. */
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_Safe_sequence_base* _M_sequence;
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/** The version number of this iterator. The sentinel value 0 is
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* used to indicate an invalidated iterator (i.e., one that is
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* singular because of an operation on the container). This
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* version number must equal the version number in the sequence
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* referenced by _M_sequence for the iterator to be
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* non-singular.
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*/
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unsigned int _M_version;
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/** Pointer to the previous iterator in the sequence's list of
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iterators. Only valid when _M_sequence != NULL. */
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_Safe_iterator_base* _M_prior;
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/** Pointer to the next iterator in the sequence's list of
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iterators. Only valid when _M_sequence != NULL. */
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_Safe_iterator_base* _M_next;
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protected:
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/** Initializes the iterator and makes it singular. */
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_Safe_iterator_base()
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: _M_sequence(0), _M_version(0), _M_prior(0), _M_next(0)
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{ }
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/** Initialize the iterator to reference the sequence pointed to
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* by @p __seq. @p __constant is true when we are initializing a
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* constant iterator, and false if it is a mutable iterator. Note
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* that @p __seq may be NULL, in which case the iterator will be
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* singular. Otherwise, the iterator will reference @p __seq and
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* be nonsingular.
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*/
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_Safe_iterator_base(const _Safe_sequence_base* __seq, bool __constant)
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: _M_sequence(0), _M_version(0), _M_prior(0), _M_next(0)
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{ this->_M_attach(const_cast<_Safe_sequence_base*>(__seq), __constant); }
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/** Initializes the iterator to reference the same sequence that
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@p __x does. @p __constant is true if this is a constant
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iterator, and false if it is mutable. */
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_Safe_iterator_base(const _Safe_iterator_base& __x, bool __constant)
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: _M_sequence(0), _M_version(0), _M_prior(0), _M_next(0)
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{ this->_M_attach(__x._M_sequence, __constant); }
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~_Safe_iterator_base() { this->_M_detach(); }
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/** For use in _Safe_iterator. */
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__gnu_cxx::__mutex&
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_M_get_mutex() throw ();
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/** Attaches this iterator to the given sequence, detaching it
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* from whatever sequence it was attached to originally. If the
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* new sequence is the NULL pointer, the iterator is left
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* unattached.
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*/
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void
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_M_attach(_Safe_sequence_base* __seq, bool __constant);
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/** Likewise, but not thread-safe. */
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void
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_M_attach_single(_Safe_sequence_base* __seq, bool __constant) throw ();
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/** Detach the iterator for whatever sequence it is attached to,
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* if any.
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*/
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void
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_M_detach();
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public:
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/** Likewise, but not thread-safe. */
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void
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_M_detach_single() throw ();
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/** Determines if we are attached to the given sequence. */
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bool
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_M_attached_to(const _Safe_sequence_base* __seq) const
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{ return _M_sequence == __seq; }
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/** Is this iterator singular? */
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_GLIBCXX_PURE bool
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_M_singular() const throw ();
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/** Can we compare this iterator to the given iterator @p __x?
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Returns true if both iterators are nonsingular and reference
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the same sequence. */
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_GLIBCXX_PURE bool
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_M_can_compare(const _Safe_iterator_base& __x) const throw ();
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/** Invalidate the iterator, making it singular. */
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void
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_M_invalidate()
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{ _M_version = 0; }
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/** Reset all member variables */
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void
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_M_reset() throw ();
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/** Unlink itself */
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void
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_M_unlink() throw ()
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{
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if (_M_prior)
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_M_prior->_M_next = _M_next;
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if (_M_next)
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_M_next->_M_prior = _M_prior;
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}
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};
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/** Iterators that derive from _Safe_iterator_base can be determined singular
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* or non-singular.
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**/
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inline bool
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__check_singular_aux(const _Safe_iterator_base* __x)
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{ return __x->_M_singular(); }
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/**
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* @brief Base class that supports tracking of iterators that
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* reference a sequence.
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*
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* The %_Safe_sequence_base class provides basic support for
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* tracking iterators into a sequence. Sequences that track
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* iterators must derived from %_Safe_sequence_base publicly, so
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* that safe iterators (which inherit _Safe_iterator_base) can
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* attach to them. This class contains two linked lists of
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* iterators, one for constant iterators and one for mutable
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* iterators, and a version number that allows very fast
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* invalidation of all iterators that reference the container.
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*
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* This class must ensure that no operation on it may throw an
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* exception, otherwise @a safe sequences may fail to provide the
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* exception-safety guarantees required by the C++ standard.
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*/
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class _Safe_sequence_base
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{
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friend class _Safe_iterator_base;
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public:
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/// The list of mutable iterators that reference this container
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_Safe_iterator_base* _M_iterators;
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/// The list of constant iterators that reference this container
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_Safe_iterator_base* _M_const_iterators;
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/// The container version number. This number may never be 0.
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mutable unsigned int _M_version;
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protected:
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// Initialize with a version number of 1 and no iterators
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_Safe_sequence_base() _GLIBCXX_NOEXCEPT
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: _M_iterators(0), _M_const_iterators(0), _M_version(1)
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{ }
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#if __cplusplus >= 201103L
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_Safe_sequence_base(const _Safe_sequence_base&) noexcept
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: _Safe_sequence_base() { }
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// Move constructor swap iterators.
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_Safe_sequence_base(_Safe_sequence_base&& __seq) noexcept
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: _Safe_sequence_base()
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{ _M_swap(__seq); }
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#endif
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/** Notify all iterators that reference this sequence that the
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sequence is being destroyed. */
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~_Safe_sequence_base()
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{ this->_M_detach_all(); }
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/** Detach all iterators, leaving them singular. */
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void
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_M_detach_all();
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/** Detach all singular iterators.
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* @post for all iterators i attached to this sequence,
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* i->_M_version == _M_version.
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*/
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void
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_M_detach_singular();
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/** Revalidates all attached singular iterators. This method may
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* be used to validate iterators that were invalidated before
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* (but for some reason, such as an exception, need to become
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* valid again).
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*/
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void
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_M_revalidate_singular();
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/** Swap this sequence with the given sequence. This operation
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* also swaps ownership of the iterators, so that when the
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* operation is complete all iterators that originally referenced
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* one container now reference the other container.
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*/
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void
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_M_swap(_Safe_sequence_base& __x) _GLIBCXX_USE_NOEXCEPT;
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/** For use in _Safe_sequence. */
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__gnu_cxx::__mutex&
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_M_get_mutex() throw ();
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/** Invalidates all iterators. */
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void
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_M_invalidate_all() const
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{ if (++_M_version == 0) _M_version = 1; }
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private:
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/** Attach an iterator to this sequence. */
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void
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_M_attach(_Safe_iterator_base* __it, bool __constant);
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/** Likewise but not thread safe. */
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void
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_M_attach_single(_Safe_iterator_base* __it, bool __constant) throw ();
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/** Detach an iterator from this sequence */
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void
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_M_detach(_Safe_iterator_base* __it);
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/** Likewise but not thread safe. */
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void
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_M_detach_single(_Safe_iterator_base* __it) throw ();
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};
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} // namespace __gnu_debug
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#endif
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