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/*
* Copyright (C) 2006, 2007, 2009, 2010 Apple Inc. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
*/
#ifndef TreeShared_h
#define TreeShared_h
#include <wtf/Assertions.h>
#include <wtf/Noncopyable.h>
#include <wtf/Threading.h>
namespace WebCore {
#ifndef NDEBUG
template<typename T> class TreeShared;
template<typename T> void adopted(TreeShared<T>*);
#endif
template<typename T> class TreeShared {
WTF_MAKE_NONCOPYABLE(TreeShared);
public:
TreeShared()
: m_refCount(1)
, m_parent(0)
#ifndef NDEBUG
, m_adoptionIsRequired(true)
#endif
{
ASSERT(isMainThread());
#ifndef NDEBUG
m_deletionHasBegun = false;
m_inRemovedLastRefFunction = false;
#endif
}
virtual ~TreeShared()
{
ASSERT(isMainThread());
ASSERT(!m_refCount);
ASSERT(m_deletionHasBegun);
ASSERT(!m_adoptionIsRequired);
}
void ref()
{
ASSERT(isMainThread());
ASSERT(!m_deletionHasBegun);
ASSERT(!m_inRemovedLastRefFunction);
ASSERT(!m_adoptionIsRequired);
++m_refCount;
}
void deref()
{
ASSERT(isMainThread());
ASSERT(m_refCount >= 0);
ASSERT(!m_deletionHasBegun);
ASSERT(!m_inRemovedLastRefFunction);
ASSERT(!m_adoptionIsRequired);
if (--m_refCount <= 0 && !m_parent) {
#ifndef NDEBUG
m_inRemovedLastRefFunction = true;
#endif
removedLastRef();
}
}
bool hasOneRef() const
{
ASSERT(!m_deletionHasBegun);
ASSERT(!m_inRemovedLastRefFunction);
return m_refCount == 1;
}
int refCount() const
{
return m_refCount;
}
void setParent(T* parent)
{
ASSERT(isMainThread());
m_parent = parent;
}
T* parent() const
{
ASSERT(isMainThread());
return m_parent;
}
#ifndef NDEBUG
bool m_deletionHasBegun;
bool m_inRemovedLastRefFunction;
#endif
protected:
virtual void removedLastRef()
{
#ifndef NDEBUG
m_deletionHasBegun = true;
#endif
delete this;
}
private:
#ifndef NDEBUG
friend void adopted<>(TreeShared<T>*);
#endif
int m_refCount;
T* m_parent;
#ifndef NDEBUG
bool m_adoptionIsRequired;
#endif
};
#ifndef NDEBUG
template<typename T> inline void adopted(TreeShared<T>* object)
{
if (!object)
return;
ASSERT(!object->m_deletionHasBegun);
ASSERT(!object->m_inRemovedLastRefFunction);
object->m_adoptionIsRequired = false;
}
#endif
}
#endif // TreeShared.h
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