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/*
* Copyright (C) 2006, 2007, 2008, 2009, 2010, 2013 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 RefCounted_h
#define RefCounted_h
#include <wtf/Assertions.h>
#include <wtf/FastMalloc.h>
#include <wtf/Noncopyable.h>
namespace WTF {
#ifdef NDEBUG
#define CHECK_REF_COUNTED_LIFECYCLE 0
#else
#define CHECK_REF_COUNTED_LIFECYCLE 1
#endif
// This base class holds the non-template methods and attributes.
// The RefCounted class inherits from it reducing the template bloat
// generated by the compiler (technique called template hoisting).
class RefCountedBase {
public:
void ref()
{
#if CHECK_REF_COUNTED_LIFECYCLE
ASSERT(!m_deletionHasBegun);
ASSERT(!m_adoptionIsRequired);
#endif
++m_refCount;
}
bool hasOneRef() const
{
#if CHECK_REF_COUNTED_LIFECYCLE
ASSERT(!m_deletionHasBegun);
#endif
return m_refCount == 1;
}
unsigned refCount() const
{
return m_refCount;
}
void relaxAdoptionRequirement()
{
#if CHECK_REF_COUNTED_LIFECYCLE
ASSERT(!m_deletionHasBegun);
ASSERT(m_adoptionIsRequired);
m_adoptionIsRequired = false;
#endif
}
protected:
RefCountedBase()
: m_refCount(1)
#if CHECK_REF_COUNTED_LIFECYCLE
, m_deletionHasBegun(false)
, m_adoptionIsRequired(true)
#endif
{
}
~RefCountedBase()
{
#if CHECK_REF_COUNTED_LIFECYCLE
ASSERT(m_deletionHasBegun);
ASSERT(!m_adoptionIsRequired);
#endif
}
// Returns whether the pointer should be freed or not.
bool derefBase()
{
#if CHECK_REF_COUNTED_LIFECYCLE
ASSERT(!m_deletionHasBegun);
ASSERT(!m_adoptionIsRequired);
#endif
ASSERT(m_refCount);
unsigned tempRefCount = m_refCount - 1;
if (!tempRefCount) {
#if CHECK_REF_COUNTED_LIFECYCLE
m_deletionHasBegun = true;
#endif
return true;
}
m_refCount = tempRefCount;
return false;
}
#if CHECK_REF_COUNTED_LIFECYCLE
bool deletionHasBegun() const
{
return m_deletionHasBegun;
}
#endif
private:
#if CHECK_REF_COUNTED_LIFECYCLE
friend void adopted(RefCountedBase*);
#endif
unsigned m_refCount;
#if CHECK_REF_COUNTED_LIFECYCLE
bool m_deletionHasBegun;
bool m_adoptionIsRequired;
#endif
};
#if CHECK_REF_COUNTED_LIFECYCLE
inline void adopted(RefCountedBase* object)
{
if (!object)
return;
ASSERT(!object->m_deletionHasBegun);
object->m_adoptionIsRequired = false;
}
#endif
template<typename T> class RefCounted : public RefCountedBase {
WTF_MAKE_NONCOPYABLE(RefCounted); WTF_MAKE_FAST_ALLOCATED;
public:
void deref()
{
if (derefBase())
delete static_cast<T*>(this);
}
protected:
RefCounted() { }
~RefCounted()
{
}
};
} // namespace WTF
using WTF::RefCounted;
#endif // RefCounted_h
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