JavaScriptCore-7600.1.4.9.tar.gz

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

diff --git a/heap/CopyWriteBarrier.h b/heap/CopyWriteBarrier.h
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+/*
+ * Copyright (C) 2014 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 CopyWriteBarrier_h
+#define CopyWriteBarrier_h
+
+#include "Heap.h"
+
+namespace JSC {
+
+template <typename T>
+class CopyWriteBarrier {
+public:
+    CopyWriteBarrier()
+        : m_value(0)
+    {
+    }
+    
+    CopyWriteBarrier(VM& vm, const JSCell* owner, T& value)
+    {
+        this->set(vm, owner, &value);
+    }
+    
+    CopyWriteBarrier(VM& vm, const JSCell* owner, T* value)
+    {
+        this->set(vm, owner, value);
+    }
+    
+    bool operator!() const { return !m_value; }
+    
+    typedef T* (CopyWriteBarrier::*UnspecifiedBoolType);
+    operator UnspecifiedBoolType*() const { return m_value ? reinterpret_cast<UnspecifiedBoolType*>(1) : 0; }
+    
+    T* get() const
+    {
+        return m_value;
+    }
+    
+    T* operator*() const
+    {
+        return get();
+    }
+    
+    T* operator->() const
+    {
+        return get();
+    }
+    
+    void set(VM& vm, const JSCell* owner, T* value)
+    {
+        this->m_value = value;
+        vm.heap.writeBarrier(owner);
+    }
+    
+    void setWithoutWriteBarrier(T* value)
+    {
+        this->m_value = value;
+    }
+    
+    void clear() { m_value = 0; }
+
+private:
+    T* m_value;
+};
+
+} // namespace JSC
+
+#endif // CopyWriteBarrier_h