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diff --git a/Source/JavaScriptCore/wtf/text/StringImplBase.h b/Source/JavaScriptCore/wtf/text/StringImplBase.h
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+++ b/Source/JavaScriptCore/wtf/text/StringImplBase.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. ``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 StringImplBase_h
+#define StringImplBase_h
+
+#include <wtf/Noncopyable.h>
+#include <wtf/unicode/Unicode.h>
+
+namespace WTF {
+
+class StringImplBase : public Noncopyable {
+public:
+    bool isStringImpl() { return (m_refCountAndFlags & s_refCountInvalidForStringImpl) != s_refCountInvalidForStringImpl; }
+    unsigned length() const { return m_length; }
+    void ref() { m_refCountAndFlags += s_refCountIncrement; }
+
+protected:
+    enum BufferOwnership {
+        BufferInternal,
+        BufferOwned,
+        BufferSubstring,
+        BufferShared,
+    };
+
+    using Noncopyable::operator new;
+    void* operator new(size_t, void* inPlace) { ASSERT(inPlace); return inPlace; }
+
+    // For SmallStringStorage, which allocates an array and uses an in-place new.
+    StringImplBase() { }
+
+    StringImplBase(unsigned length, BufferOwnership ownership)
+        : m_refCountAndFlags(s_refCountIncrement | s_refCountFlagShouldReportedCost | ownership)
+        , m_length(length)
+    {
+        ASSERT(isStringImpl());
+    }
+
+    enum StaticStringConstructType { ConstructStaticString };
+    StringImplBase(unsigned length, StaticStringConstructType)
+        : m_refCountAndFlags(s_refCountFlagStatic | s_refCountFlagIsIdentifier | BufferOwned)
+        , m_length(length)
+    {
+        ASSERT(isStringImpl());
+    }
+
+    // This constructor is not used when creating StringImpl objects,
+    // and sets the flags into a state marking the object as such.
+    enum NonStringImplConstructType { ConstructNonStringImpl };
+    StringImplBase(NonStringImplConstructType)
+        : m_refCountAndFlags(s_refCountIncrement | s_refCountInvalidForStringImpl)
+        , m_length(0)
+    {
+        ASSERT(!isStringImpl());
+    }
+
+    // The bottom 7 bits hold flags, the top 25 bits hold the ref count.
+    // When dereferencing StringImpls we check for the ref count AND the
+    // static bit both being zero - static strings are never deleted.
+    static const unsigned s_refCountMask = 0xFFFFFF80;
+    static const unsigned s_refCountIncrement = 0x80;
+    static const unsigned s_refCountFlagStatic = 0x40;
+    static const unsigned s_refCountFlagHasTerminatingNullCharacter = 0x20;
+    static const unsigned s_refCountFlagIsAtomic = 0x10;
+    static const unsigned s_refCountFlagShouldReportedCost = 0x8;
+    static const unsigned s_refCountFlagIsIdentifier = 0x4;
+    static const unsigned s_refCountMaskBufferOwnership = 0x3;
+    // An invalid permutation of flags (static & shouldReportedCost - static strings do not
+    // set shouldReportedCost in the constructor, and this bit is only ever cleared, not set).
+    // Used by "ConstructNonStringImpl" constructor, above.
+    static const unsigned s_refCountInvalidForStringImpl = s_refCountFlagStatic | s_refCountFlagShouldReportedCost;
+
+    unsigned m_refCountAndFlags;
+    unsigned m_length;
+};
+
+} // namespace WTF
+
+using WTF::StringImplBase;
+
+#endif