A thread safe CSS calc parser for sizes

Source/core/css/parser/MediaQueryCalcParser.h

+// 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 MediaQueryCalcParser_h
+#define MediaQueryCalcParser_h
+
+#include "core/css/parser/MediaQueryToken.h"
+#include "wtf/text/WTFString.h"
+
+namespace WebCore {
+
+struct MediaQueryCalcValue {
+    double value;
+    UChar operation;
+
+    MediaQueryCalcValue()
+        : value(0)
+        , operation(0)
+    {
+    }
+};
+
+class MediaQueryCalcParser {
+
+public:
+    static int parse(MediaQueryTokenIterator start, MediaQueryTokenIterator end, unsigned fontSize, unsigned viewportWidth, unsigned viewportHeight);
+
+private:
+    MediaQueryCalcParser(unsigned fontSize, unsigned viewportWidth, unsigned viewportHeight)
+        : m_fontSize(fontSize)
+        , m_viewportWidth(viewportWidth)
+        , m_viewportHeight(viewportHeight)
+    {
+    }
+
+    bool calcToReversePolishNotation(MediaQueryTokenIterator start, MediaQueryTokenIterator end);
+    bool calculate(int& result);
+    bool appendNumber(const MediaQueryToken&);
+    bool handleOperator(Vector<MediaQueryToken>& stack, const MediaQueryToken&);
+    void appendOperator(const MediaQueryToken&);
+
+    Vector<MediaQueryCalcValue> m_valueList;
+    unsigned m_fontSize;
+    unsigned m_viewportWidth;
+    unsigned m_viewportHeight;
+};
+
+} // namespace WebCore
+
+#endif // MediaQueryCalcParser_h
+