Use VTTScanner for VTT cue settings parsing

Source/core/html/track/vtt/VTTScanner.cpp

 /*
  * Copyright (c) 2013, Opera Software ASA. 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
@@ skipping 48 matching lines @@
     bool matched;
     if (m_is8Bit)
         matched = WTF::equal(m_data.characters8, characters, charactersCount);
     else
         matched = WTF::equal(m_data.characters16, characters, charactersCount);
     if (matched)
         advance(charactersCount);
     return matched;
 }
 
+bool VTTScanner::scanRun(const Run& run, const String& toMatch)
+{
+    ASSERT(run.start() == position());
+    ASSERT(run.start() <= end());
+    ASSERT(run.end() >= run.start());
+    ASSERT(run.end() <= end());
+    size_t matchLength = run.length();
+    if (toMatch.length() > matchLength)
+        return false;
+    bool matched;
+    if (m_is8Bit)
+        matched = WTF::equal(toMatch.impl(), m_data.characters8, matchLength);
+    else
+        matched = WTF::equal(toMatch.impl(), m_data.characters16, matchLength);
+    if (matched)
+        seekTo(run.end());
+    return matched;
+}
+
+void VTTScanner::skipRun(const Run& run)
+{
+    ASSERT(run.start() <= end());
+    ASSERT(run.end() >= run.start());
+    ASSERT(run.end() <= end());
+    seekTo(run.end());
+}
+
+String VTTScanner::extractString(const Run& run)
+{
+    ASSERT(run.start() == position());
+    ASSERT(run.start() <= end());
+    ASSERT(run.end() >= run.start());
+    ASSERT(run.end() <= end());
+    String s;
+    if (m_is8Bit)
+        s = String(m_data.characters8, run.length());
+    else
+        s = String(m_data.characters16, run.length());
+    seekTo(run.end());
+    return s;
+}
+
 String VTTScanner::restOfInputAsString()
 {
-    ASSERT(position() <= end());
-    String s;
-    if (m_is8Bit)
-        s = String(m_data.characters8, m_end.characters8 - m_data.characters8);
-    else
-        s = String(m_data.characters16, m_end.characters16 - m_data.characters16);
-    seekTo(end());
-    return s;
+    Run rest(position(), end(), m_is8Bit);
+    return extractString(rest);
 }
 
 unsigned VTTScanner::scanDigits(int& number)
 {
     Run runOfDigits = collectWhile<isASCIIDigit>();
     if (runOfDigits.isEmpty()) {
         number = 0;
         return 0;
     }
     bool validNumber;
     size_t numDigits = runOfDigits.length();
     if (m_is8Bit)
         number = charactersToInt(m_data.characters8, numDigits, &validNumber);
     else
         number = charactersToInt(m_data.characters16, numDigits, &validNumber);
 
     // Since we know that scanDigits only scanned valid (ASCII) digits (and
     // hence that's what got passed to charactersToInt()), the remaining
     // failure mode for charactersToInt() is overflow, so if |validNumber| is
     // not true, then set |number| to the maximum int value.
     if (!validNumber)
         number = std::numeric_limits<int>::max();
     // Consume the digits.
     seekTo(runOfDigits.end());
     return numDigits;
 }
 
 }