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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 "Heap.h"
#include "GCHandle.h"
namespace JSC {
// A smart pointer whose get() function returns 0 for cells awaiting destruction.
template <typename T> class WeakGCPtr {
WTF_MAKE_NONCOPYABLE(WeakGCPtr);
public:
WeakGCPtr()
: m_ptr(0)
{
}
WeakGCPtr(T* ptr) { assign(ptr); }
~WeakGCPtr()
{
if (m_ptr)
m_ptr->pool()->free(m_ptr);
}
T* get() const
{
if (m_ptr && m_ptr->isValidPtr())
return static_cast<T*>(m_ptr->get());
return 0;
}
bool clear(JSCell* p)
{
if (!m_ptr || m_ptr->get() != p)
return false;
m_ptr->pool()->free(m_ptr);
m_ptr = 0;
return true;
}
T& operator*() const { return *get(); }
T* operator->() const { return get(); }
bool operator!() const { return !get(); }
// This conversion operator allows implicit conversion to bool but not to other integer types.
#if COMPILER(WINSCW)
operator bool() const { return m_ptr; }
#else
typedef WeakGCHandle* WeakGCPtr::*UnspecifiedBoolType;
operator UnspecifiedBoolType() const { return get() ? &WeakGCPtr::m_ptr : 0; }
#endif
WeakGCPtr& operator=(T*);
#if !ASSERT_DISABLED
bool hasDeadObject() const { return !!m_ptr; }
#endif
private:
void assign(JSCell* ptr)
{
ASSERT(ptr);
if (m_ptr)
m_ptr->set(ptr);
else
m_ptr = Heap::heap(ptr)->addWeakGCHandle(ptr);
}
WeakGCHandle* m_ptr;
};
template <typename T> inline WeakGCPtr<T>& WeakGCPtr<T>::operator=(T* optr)
{
assign(optr);
return *this;
}
template <typename T, typename U> inline bool operator==(const WeakGCPtr<T>& a, const WeakGCPtr<U>& b)
{
return a.get() == b.get();
}
template <typename T, typename U> inline bool operator==(const WeakGCPtr<T>& a, U* b)
{
return a.get() == b;
}
template <typename T, typename U> inline bool operator==(T* a, const WeakGCPtr<U>& b)
{
return a == b.get();
}
template <typename T, typename U> inline bool operator!=(const WeakGCPtr<T>& a, const WeakGCPtr<U>& b)
{
return a.get() != b.get();
}
template <typename T, typename U> inline bool operator!=(const WeakGCPtr<T>& a, U* b)
{
return a.get() != b;
}
template <typename T, typename U> inline bool operator!=(T* a, const WeakGCPtr<U>& b)
{
return a != b.get();
}
template <typename T, typename U> inline WeakGCPtr<T> static_pointer_cast(const WeakGCPtr<U>& p)
{
return WeakGCPtr<T>(static_cast<T*>(p.get()));
}
template <typename T, typename U> inline WeakGCPtr<T> const_pointer_cast(const WeakGCPtr<U>& p)
{
return WeakGCPtr<T>(const_cast<T*>(p.get()));
}
template <typename T> inline T* get(const WeakGCPtr<T>& p)
{
return p.get();
}
} // namespace JSC
#endif // WeakGCPtr_h
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