JavaScriptCore-1097.3.tar.gz

[apple/javascriptcore.git] / heap / WeakImpl.h

diff --git a/heap/WeakImpl.h b/heap/WeakImpl.h
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+/*
+ * 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. 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 WeakImpl_h
+#define WeakImpl_h
+
+#include "JSValue.h"
+
+namespace JSC {
+
+class WeakHandleOwner;
+
+class WeakImpl {
+public:
+    enum State {
+        Live        = 0x0,
+        Dead        = 0x1,
+        Finalized   = 0x2,
+        Deallocated = 0x3
+    };
+
+    enum {
+        StateMask   = 0x3
+    };
+
+    WeakImpl();
+    WeakImpl(JSValue, WeakHandleOwner*, void* context);
+
+    State state();
+    void setState(State);
+
+    const JSValue& jsValue();
+    WeakHandleOwner* weakHandleOwner();
+    void* context();
+
+    static WeakImpl* asWeakImpl(JSValue*);
+
+private:
+    const JSValue m_jsValue;
+    WeakHandleOwner* m_weakHandleOwner;
+    void* m_context;
+};
+
+inline WeakImpl::WeakImpl()
+    : m_weakHandleOwner(0)
+    , m_context(0)
+{
+    setState(Deallocated);
+}
+
+inline WeakImpl::WeakImpl(JSValue jsValue, WeakHandleOwner* weakHandleOwner, void* context)
+    : m_jsValue(jsValue)
+    , m_weakHandleOwner(weakHandleOwner)
+    , m_context(context)
+{
+    ASSERT(state() == Live);
+    ASSERT(m_jsValue && m_jsValue.isCell());
+}
+
+inline WeakImpl::State WeakImpl::state()
+{
+    return static_cast<State>(reinterpret_cast<uintptr_t>(m_weakHandleOwner) & StateMask);
+}
+
+inline void WeakImpl::setState(WeakImpl::State state)
+{
+    ASSERT(state >= this->state());
+    m_weakHandleOwner = reinterpret_cast<WeakHandleOwner*>((reinterpret_cast<uintptr_t>(m_weakHandleOwner) & ~StateMask) | state);
+}
+
+inline const JSValue& WeakImpl::jsValue()
+{
+    return m_jsValue;
+}
+
+inline WeakHandleOwner* WeakImpl::weakHandleOwner()
+{
+    return reinterpret_cast<WeakHandleOwner*>((reinterpret_cast<uintptr_t>(m_weakHandleOwner) & ~StateMask));
+}
+
+inline void* WeakImpl::context()
+{
+    return m_context;
+}
+
+inline WeakImpl* WeakImpl::asWeakImpl(JSValue* slot)
+{
+    return reinterpret_cast<WeakImpl*>(reinterpret_cast<char*>(slot) + OBJECT_OFFSETOF(WeakImpl, m_jsValue));
+}
+
+} // namespace JSC
+
+#endif // WeakImpl_h