A thread safe CSS calc parser for sizes

Source/core/css/parser/SizesCalcParser.h

Index: Source/core/css/parser/SizesCalcParser.h
diff --git a/Source/core/css/parser/SizesCalcParser.h b/Source/core/css/parser/SizesCalcParser.h
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+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef SizesCalcParser_h
+#define SizesCalcParser_h
+
+#include "core/css/MediaValues.h"
+#include "core/css/parser/MediaQueryToken.h"
+#include "wtf/text/WTFString.h"
+
+namespace WebCore {
+
+struct SizesCalcValue {
+    double value;
+    bool isLength;
+    UChar operation;
+
+    SizesCalcValue()
+        : value(0)
+        , isLength(false)
+        , operation(0)
+    {
+    }
+
+    SizesCalcValue(double numericValue, bool length)
+        : value(numericValue)
+        , isLength(length)
+        , operation(0)
+    {
+    }
+};
+
+class SizesCalcParser {
+
+public:
+    static bool parse(MediaQueryTokenIterator start, MediaQueryTokenIterator end, PassRefPtr<MediaValues>, unsigned& result);
+
+private:
+    SizesCalcParser(PassRefPtr<MediaValues> mediaValues)
+        : m_mediaValues(mediaValues)
+    {
+    }
+
+    bool calcToReversePolishNotation(MediaQueryTokenIterator start, MediaQueryTokenIterator end);
+    bool calculate(unsigned& result);
+    void appendNumber(const MediaQueryToken&);
+    bool appendLength(const MediaQueryToken&);
+    bool handleOperator(Vector<MediaQueryToken>& stack, const MediaQueryToken&);
+    void appendOperator(const MediaQueryToken&);
+
+    Vector<SizesCalcValue> m_valueList;
+    RefPtr<MediaValues> m_mediaValues;
+};
+
+} // namespace WebCore
+
+#endif // SizesCalcParser_h
+