safe_base.h
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// Safe sequence/iterator base implementation -*- C++ -*-
// Copyright (C) 2003-2013 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 @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() throw ();
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) throw ();
/** Detach the iterator for whatever sequence it is attached to,
* if any.
*/
void _M_detach();
/** Likewise, but not thread-safe. */
void _M_detach_single() throw ();
/** 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? */
_GLIBCXX_PURE bool _M_singular() const throw ();
/** Can we compare this iterator to the given iterator @p __x?
Returns true if both iterators are nonsingular and reference
the same sequence. */
_GLIBCXX_PURE bool _M_can_compare(const _Safe_iterator_base& __x) const throw ();
/** Invalidate the iterator, making it singular. */
void
_M_invalidate()
{ _M_version = 0; }
/** Reset all member variables */
void
_M_reset() throw ();
/** Unlink itself */
void
_M_unlink() throw ()
{
if (_M_prior)
_M_prior->_M_next = _M_next;
if (_M_next)
_M_next->_M_prior = _M_prior;
}
};
/**
* @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 @a 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() throw ();
public:
/** Invalidates all iterators. */
void
_M_invalidate_all() const
{ if (++_M_version == 0) _M_version = 1; }
/** Attach an iterator to this sequence. */
void
_M_attach(_Safe_iterator_base* __it, bool __constant);
/** Likewise but not thread safe. */
void
_M_attach_single(_Safe_iterator_base* __it, bool __constant) throw ();
/** Detach an iterator from this sequence */
void
_M_detach(_Safe_iterator_base* __it);
/** Likewise but not thread safe. */
void
_M_detach_single(_Safe_iterator_base* __it) throw ();
};
} // namespace __gnu_debug
#endif