Handle buffer boundaries in the WebVTT parser

Source/core/html/track/BufferedLineReader.h

+/*
+ * Copyright (C) 2013, Opera Software ASA. All rights reserved.
+ *
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+ */
+
+#ifndef BufferedLineReader_h
+#define BufferedLineReader_h
+
+#include "platform/text/SegmentedString.h"
+#include "wtf/text/StringBuilder.h"
+
+namespace WebCore {
+
+// Line collection helper for the WebVTT Parser.
+//
+// Converts a stream of data (== a sequence of Strings) into a set of
+// lines. CR, LR or CRLF are considered linebreaks. Normalizes NULs (U+0000)
+// to 'REPLACEMENT CHARACTER' (U+FFFD) and does not return the linebreaks as
+// part of the result.
+class BufferedLineReader {
+public:

[jochen (gone - plz use gerrit), 2013/11/08 11:59:44]

nit. WTF_MAKE_NONCOPYABLE

+    BufferedLineReader()
+        : m_endOfStream(false)
+        , m_maybeSkipLF(false) { }
+
+    // Append data to the internal buffer.
+    void append(const String& data)
+    {
+        ASSERT(!m_endOfStream);
+        m_buffer.append(SegmentedString(data));
+    }
+
+    // Indicate that no more data will be appended. This will cause any
+    // potentially "unterminated" line to be returned from getLine.
+    void setEndOfStream(bool endOfStream) { m_endOfStream = endOfStream; }

[jochen (gone - plz use gerrit), 2013/11/08 11:59:44]

will you ever setEndOfStream(false)? Maybe leave out the bool parameter?

+
+    // Attempt to read a line from the internal buffer (fed via append).
+    // If successful, true is returned and |line| is set to the line that was
+    // read. If no line could be read false is returned.
+    bool getLine(String& line);

[jochen (gone - plz use gerrit), 2013/11/08 11:59:44]

I'd use String* to make it clear that this is an out-param

+
+    // Returns true if EOS has been reached proper.
+    bool isAtEOS() const { return m_endOfStream && m_buffer.isEmpty(); }

[jochen (gone - plz use gerrit), 2013/11/08 11:59:44]

isAtEndOfStream (to match setEndOfStream() above)

+
+private:
+    // Consume the next character the buffer if it is the character |c|.
+    void scanCharacter(UChar c)
+    {
+        ASSERT(!m_buffer.isEmpty());
+        if (m_buffer.currentChar() == c)
+            m_buffer.advance();
+    }
+
+    SegmentedString m_buffer;
+    StringBuilder m_lineBuffer;
+    bool m_endOfStream;
+    bool m_maybeSkipLF;
+};
+
+} // namespace WebCore
+
+#endif