// initial methods
 public void parseFrom(List fromList) throws QueryParsingException {
   if (fromList == null || fromList.size() == 0) {
     throw new QueryParsingException("Invalid query: Source of the query is not specified.");
   }
   for (int i = 0, n = fromList.size(); i < n; i++) {
     String from = (String) fromList.get(i);
     parseSource(from);
   }
 }
 public void parseFrom(String from) throws QueryParsingException {
   parseSource(from);
 }