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diff --git a/Source/WTF/wtf/SetForScope.h b/Source/WTF/wtf/SetForScope.h
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+/*
+ * Copyright (C) 2011 Google Inc. All rights reserved.
+ * Copyright (C) 2016 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 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 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.
+ */
+
+#pragma once
+
+#include <wtf/Noncopyable.h>
+#include <wtf/StdLibExtras.h>
+
+namespace WTF {
+
+// SetForScope<> is useful for setting a variable to a new value only within a
+// particular scope. An SetForScope<> object changes a variable to its original
+// value upon destruction, making it an alternative to writing "var = false;"
+// or "var = oldVal;" at all of a block's exit points.
+//
+// This should be obvious, but note that an SetForScope<> instance should have a
+// shorter lifetime than its scopedVariable, to prevent invalid memory writes
+// when the SetForScope<> object is destroyed.
+
+template<typename T>
+class SetForScope {
+    WTF_MAKE_NONCOPYABLE(SetForScope);
+public:
+    SetForScope(T& scopedVariable)
+        : m_scopedVariable(scopedVariable)
+        , m_originalValue(scopedVariable)
+    {
+    }
+    template<typename U>
+    SetForScope(T& scopedVariable, U&& newValue)
+        : SetForScope(scopedVariable)
+    {
+        m_scopedVariable = std::forward<U>(newValue);
+    }
+
+    ~SetForScope()
+    {
+        m_scopedVariable = WTFMove(m_originalValue);
+    }
+
+private:
+    T& m_scopedVariable;
+    T m_originalValue;
+};
+
+}
+
+using WTF::SetForScope;