JavaScriptCore-903.tar.gz

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

diff --git a/heap/Local.h b/heap/Local.h
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+/*
+ * Copyright (C) 2010 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 Local_h
+#define Local_h
+
+#include "Handle.h"
+#include "JSGlobalData.h"
+
+/*
+    A strongly referenced handle whose lifetime is temporary, limited to a given
+    LocalScope. Use Locals for local values on the stack. It is an error to
+    create a Local outside of any LocalScope.
+*/
+
+namespace JSC {
+
+template <typename T> class Local : public Handle<T> {
+    friend class LocalScope;
+    using Handle<T>::slot;
+
+public:
+    typedef typename Handle<T>::ExternalType ExternalType;
+
+    Local(JSGlobalData&, ExternalType = ExternalType());
+    Local(JSGlobalData&, Handle<T>);
+    Local(const Local<T>&); // Adopting constructor. Used to return a Local to a calling function.
+
+    Local& operator=(ExternalType);
+    Local& operator=(Handle<T>);
+
+private:
+    Local(HandleSlot, ExternalType); // Used by LocalScope::release() to move a Local to a containing scope.
+    void set(ExternalType);
+};
+
+template <typename T> inline Local<T>::Local(JSGlobalData& globalData, ExternalType value)
+    : Handle<T>(globalData.allocateLocalHandle())
+{
+    set(value);
+}
+
+template <typename T> inline Local<T>::Local(JSGlobalData& globalData, Handle<T> other)
+    : Handle<T>(globalData.allocateLocalHandle())
+{
+    set(other.get());
+}
+
+template <typename T> inline Local<T>::Local(const Local<T>& other)
+    : Handle<T>(other.slot())
+{
+    const_cast<Local<T>&>(other).setSlot(0); // Prevent accidental sharing.
+}
+
+template <typename T> inline Local<T>::Local(HandleSlot slot, ExternalType value)
+    : Handle<T>(slot, value)
+{
+}
+
+template <typename T> inline Local<T>& Local<T>::operator=(ExternalType value)
+{
+    set(value);
+    return *this;
+}
+
+template <typename T> inline Local<T>& Local<T>::operator=(Handle<T> other)
+{
+    set(other.get());
+    return *this;
+}
+
+template <typename T> inline void Local<T>::set(ExternalType externalType)
+{
+    ASSERT(slot());
+    ASSERT(!HandleTypes<T>::toJSValue(externalType) || !HandleTypes<T>::toJSValue(externalType).isCell() || Heap::isMarked(HandleTypes<T>::toJSValue(externalType).asCell()));
+    *slot() = externalType;
+}
+
+
+template <typename T, unsigned inlineCapacity = 0> class LocalStack {
+    typedef typename Handle<T>::ExternalType ExternalType;
+public:
+    LocalStack(JSGlobalData& globalData)
+        : m_globalData(&globalData)
+        , m_count(0)
+    {
+    }
+
+    ExternalType peek() const
+    {
+        ASSERT(m_count > 0);
+        return m_stack[m_count - 1].get();
+    }
+
+    ExternalType pop()
+    {
+        ASSERT(m_count > 0);
+        return m_stack[--m_count].get();
+    }
+
+    void push(ExternalType value)
+    {
+        if (m_count == m_stack.size())
+            m_stack.append(Local<T>(*m_globalData, value));
+        else
+            m_stack[m_count] = value;
+        m_count++;
+    }
+
+    bool isEmpty() const { return !m_count; }
+    unsigned size() const { return m_count; }
+
+private:
+    RefPtr<JSGlobalData> m_globalData;
+    Vector<Local<T>, inlineCapacity> m_stack;
+    unsigned m_count;
+};
+
+}
+
+namespace WTF {
+
+template<typename T> struct VectorTraits<JSC::Local<T> > : SimpleClassVectorTraits {
+    static const bool needsDestruction = false;
+    static const bool canInitializeWithMemset = false;
+    static const bool canCompareWithMemcmp = false;
+};
+
+}
+
+#endif