protected void scanData()
      throws Exception
   {
      while ((! this.reader.atEOF()) && (this.builder.getResult() == null)) {
         String str = XMLUtil.read(this.reader, '&');
         char ch = str.charAt(0);
         if (ch == '&') {
            XMLUtil.processEntity(str, this.reader, this.entityResolver);
            continue;
         }

         switch (ch) {
            case '<':
               this.scanSomeTag(false, // don't allow CDATA
                                null,  // no default namespace
                                new Properties());
               break;

            case ' ':
            case '\t':
            case '\r':
            case '\n':
               // skip whitespace
               break;

            default:
               XMLUtil.errorInvalidInput(reader.getSystemID(),
                                         reader.getLineNr(),
                                         "`" + ch + "' (0x"
                                         + Integer.toHexString((int) ch)
                                         + ')');
         }
      }
   }