public Token[] tokens(String exp) throws InvalidQueryException {
    return tokens(exp, Collections.emptySet());
  }
Scan the provided query and generate a token stream to be used by the query parser.

@param exp  the query expression to scan

@return an array of tokens
@throws InvalidQueryException if the query is invalid
ambari-server/src/main/java/org/apache/ambari/server/api/predicate/QueryLexer.java