/*

* Copyright (C) 2012 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. ``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

* 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 PassWeak_h

#define PassWeak_h

#include "Assertions.h"

#include "Handle.h"

#include "NullPtr.h"

#include "TypeTraits.h"

namespace JSC {

template<typename T> class Weak;

template<typename T> class PassWeak;

template<typename T> PassWeak<T> adoptWeak(HandleSlot);

template<typename T> class PassWeak : public Handle<T> {

using Handle<T>::slot;

using Handle<T>::setSlot;

public:

typedef typename Handle<T>::ExternalType ExternalType;

PassWeak() : Handle<T>() { }

PassWeak(std::nullptr_t) : Handle<T>() { }

PassWeak(JSGlobalData& globalData, ExternalType externalType = ExternalType(), WeakHandleOwner* weakOwner = 0, void* context = 0)

: Handle<T>(globalData.heap.handleHeap()->allocate())

{

HandleHeap::heapFor(slot())->makeWeak(slot(), weakOwner, context);

JSValue value = HandleTypes<T>::toJSValue(externalType);

HandleHeap::heapFor(slot())->writeBarrier(slot(), value);

*slot() = value;

}

// It somewhat breaks the type system to allow transfer of ownership out of

// a const PassWeak. However, it makes it much easier to work with PassWeak

// temporaries, and we don't have a need to use real const PassWeaks anyway.

PassWeak(const PassWeak& o) : Handle<T>(o.leakHandle()) { }

template<typename U> PassWeak(const PassWeak<U>& o) : Handle<T>(o.leakHandle()) { }

~PassWeak()

{

if (!slot())

return;

HandleHeap::heapFor(slot())->deallocate(slot());

setSlot(0);

}

ExternalType get() const { return HandleTypes<T>::getFromSlot(slot()); }

HandleSlot leakHandle() const WARN_UNUSED_RETURN;

private:

friend PassWeak adoptWeak<T>(HandleSlot);

explicit PassWeak(HandleSlot slot) : Handle<T>(slot) { }

};

template<typename T> inline HandleSlot PassWeak<T>::leakHandle() const

{

HandleSlot slot = this->slot();

const_cast<PassWeak<T>*>(this)->setSlot(0);

return slot;

}

template<typename T> PassWeak<T> adoptWeak(HandleSlot slot)

{

return PassWeak<T>(slot);

}

template<typename T, typename U> inline bool operator==(const PassWeak<T>& a, const PassWeak<U>& b)

{

return a.get() == b.get();

}

template<typename T, typename U> inline bool operator==(const PassWeak<T>& a, const Weak<U>& b)

{

return a.get() == b.get();

}

template<typename T, typename U> inline bool operator==(const Weak<T>& a, const PassWeak<U>& b)

{

return a.get() == b.get();

}

template<typename T, typename U> inline bool operator==(const PassWeak<T>& a, U* b)

{

return a.get() == b;

}

template<typename T, typename U> inline bool operator==(T* a, const PassWeak<U>& b)

{

return a == b.get();

}

template<typename T, typename U> inline bool operator!=(const PassWeak<T>& a, const PassWeak<U>& b)

{

return a.get() != b.get();

}

template<typename T, typename U> inline bool operator!=(const PassWeak<T>& a, const Weak<U>& b)

{

return a.get() != b.get();

}

template<typename T, typename U> inline bool operator!=(const Weak<T>& a, const PassWeak<U>& b)

{

return a.get() != b.get();

}

template<typename T, typename U> inline bool operator!=(const PassWeak<T>& a, U* b)

{

return a.get() != b;

}

template<typename T, typename U> inline bool operator!=(T* a, const PassWeak<U>& b)

{

return a != b.get();

}

} // namespace JSC

#endif // PassWeak_h