A thread-safe Media Query Parser

Source/core/css/parser/CSSInputStream.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 CSSInputStream_h
+#define CSSInputStream_h
+
+#include "wtf/text/WTFString.h"
+
+namespace WebCore {
+
+// The CSS Syntax spec is written as a (fixed size) look-ahead
+// tokenizer instead of a state-machine like HTML
+// so we have our own input stream class. :(
+class CSSInputStream {
+    WTF_MAKE_NONCOPYABLE(CSSInputStream);
+    WTF_MAKE_FAST_ALLOCATED;
+public:
+    CSSInputStream(String input);
+
+    UChar currentInputChar();
+    UChar peek(unsigned);
+
+    void advance(unsigned = 1);
+    void pushBack(UChar);
+
+    unsigned long long getUInt(unsigned, unsigned);
+    double getDouble(unsigned, unsigned);
+
+    template<bool characterPredicate(UChar)>
+    unsigned skipWhilePredicate(unsigned offset)
+    {
+        while ((m_offset + offset) < m_string.length() && characterPredicate(m_string[m_offset + offset]))
+            ++offset;
+        return offset;
+    }
+
+private:
+    size_t m_offset;
+    String m_string;
+};
+
+} // namespace WebCore
+
+#endif // CSSInputStream_h
+