1 files changed, 147 insertions, 0 deletions
diff --git a/Source/JavaScriptCore/heap/PassWeak.h b/Source/JavaScriptCore/heap/PassWeak.h
new file mode 100644
index 000000000..b7aa7b10d
--- /dev/null
+++ b/Source/JavaScriptCore/heap/PassWeak.h
@@ -0,0 +1,147 @@
+/*
+ * 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