/* | |
* 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 "Collector.h" | |
#include <wtf/Noncopyable.h> | |
namespace JSC { | |
// A smart pointer whose get() function returns 0 for cells awaiting destruction. | |
template <typename T> class WeakGCPtr : Noncopyable { | |
public: | |
WeakGCPtr() : m_ptr(0) { } | |
WeakGCPtr(T* ptr) { assign(ptr); } | |
T* get() const | |
{ | |
if (!m_ptr || !Heap::isCellMarked(m_ptr)) | |
return 0; | |
return m_ptr; | |
} | |
void clear(JSCell* ptr) | |
{ | |
if (ptr == m_ptr) | |
m_ptr = 0; | |
} | |
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 T* 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(T* ptr) | |
{ | |
if (ptr) | |
Heap::markCell(ptr); | |
m_ptr = ptr; | |
} | |
T* 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* getPtr(const WeakGCPtr<T>& p) | |
{ | |
return p.get(); | |
} | |
} // namespace JSC | |
#endif // WeakGCPtr_h |