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/*
* Copyright (C) 2009 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef WeakGCPtr_h
#define WeakGCPtr_h
#include "Global.h"
#include "Heap.h"
namespace JSC {
// A smart pointer whose get() function returns 0 for cells that have died
template <typename T> class WeakGCPtr : public HandleConverter<WeakGCPtr<T>, T> {
WTF_MAKE_NONCOPYABLE(WeakGCPtr);
public:
typedef typename HandleTypes<T>::ExternalType ExternalType;
WeakGCPtr()
: m_slot(0)
{
}
WeakGCPtr(JSGlobalData& globalData, Finalizer* finalizer = 0, void* context = 0)
: m_slot(globalData.allocateGlobalHandle())
{
HandleHeap::heapFor(m_slot)->makeWeak(m_slot, finalizer, context);
}
WeakGCPtr(JSGlobalData& globalData, ExternalType value, Finalizer* finalizer = 0, void* context = 0)
: m_slot(globalData.allocateGlobalHandle())
{
HandleHeap::heapFor(m_slot)->makeWeak(m_slot, finalizer, context);
internalSet(value);
}
ExternalType get() const { return HandleTypes<T>::getFromSlot(m_slot); }
void clear()
{
if (m_slot)
internalSet(ExternalType());
}
bool operator!() const { return !m_slot || !*m_slot; }
// This conversion operator allows implicit conversion to bool but not to other integer types.
typedef ExternalType (WeakGCPtr::*UnspecifiedBoolType);
operator UnspecifiedBoolType*() const { return !*this ? 0 : reinterpret_cast<UnspecifiedBoolType*>(1); }
~WeakGCPtr()
{
if (!m_slot)
return;
HandleHeap::heapFor(m_slot)->deallocate(m_slot);
}
void set(JSGlobalData& globalData, ExternalType value, Finalizer* finalizer)
{
if (!this->m_slot) {
this->m_slot = globalData.allocateGlobalHandle();
HandleHeap::heapFor(this->m_slot)->makeWeak(this->m_slot, finalizer, 0);
} else
ASSERT(HandleHeap::heapFor(this->m_slot)->getFinalizer(this->m_slot) == finalizer);
this->internalSet(value);
}
private:
void internalSet(ExternalType value)
{
ASSERT(m_slot);
JSValue newValue(HandleTypes<T>::toJSValue(value));
HandleHeap::heapFor(m_slot)->writeBarrier(m_slot, newValue);
*m_slot = newValue;
}
HandleSlot m_slot;
};
} // namespace JSC
#endif // WeakGCPtr_h
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