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src/nsUniversalDetector.cpp  view on Meta::CPAN

#define MINIMUM_THRESHOLD      (float)0.20

nsresult nsUniversalDetector::HandleData(const char* aBuf, PRUint32 aLen)
{
  if(mDone) 
    return NS_OK;

  if (aLen > 0)
    mGotData = PR_TRUE;

  //If the data starts with BOM, we know it is UTF
  if (mStart)
  {
    mStart = PR_FALSE;
    if (aLen > 3)
      switch (aBuf[0])
        {
        case '\xEF':
          if (('\xBB' == aBuf[1]) && ('\xBF' == aBuf[2]))
            // EF BB BF  UTF-8 encoded BOM
            mDetectedCharset = "UTF-8";
        break;
        case '\xFE':
          if (('\xFF' == aBuf[1]) && ('\x00' == aBuf[2]) && ('\x00' == aBuf[3]))
            // FE FF 00 00  UCS-4, unusual octet order BOM (3412)
            mDetectedCharset = "X-ISO-10646-UCS-4-3412";
          else if ('\xFF' == aBuf[1])
            // FE FF  UTF-16, big endian BOM
            mDetectedCharset = "UTF-16BE";
        break;
        case '\x00':
          if (('\x00' == aBuf[1]) && ('\xFE' == aBuf[2]) && ('\xFF' == aBuf[3]))
            // 00 00 FE FF  UTF-32, big-endian BOM
            mDetectedCharset = "UTF-32BE";
          else if (('\x00' == aBuf[1]) && ('\xFF' == aBuf[2]) && ('\xFE' == aBuf[3]))
            // 00 00 FF FE  UCS-4, unusual octet order BOM (2143)
            mDetectedCharset = "X-ISO-10646-UCS-4-2143";
        break;
        case '\xFF':
          if (('\xFE' == aBuf[1]) && ('\x00' == aBuf[2]) && ('\x00' == aBuf[3]))
            // FF FE 00 00  UTF-32, little-endian BOM
            mDetectedCharset = "UTF-32LE";
          else if ('\xFE' == aBuf[1])
            // FF FE  UTF-16, little endian BOM
            mDetectedCharset = "UTF-16LE";
        break;
      }  // switch

      if (mDetectedCharset)
      {
        mDone = PR_TRUE;
        return NS_OK;
      }
  }