diff -r 000000000000 -r 4f2f89ce4247 JavaScriptCore/runtime/WeakGCPtr.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/JavaScriptCore/runtime/WeakGCPtr.h	Fri Sep 17 09:02:29 2010 +0300
@@ -0,0 +1,139 @@
+/*
+ * 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;
+    }
+    
+    bool clear(JSCell* ptr)
+    {
+        if (ptr == m_ptr) {
+            m_ptr = 0;
+            return true;
+        }
+        return false;
+    }
+
+    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)
+    {
+        ASSERT(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