private Operator<?> genSelectPlan(String dest, QB qb, Operator<?> input,
                                    Operator<?> inputForSelectStar) throws SemanticException {
    ASTNode selExprList = qb.getParseInfo().getSelForClause(dest);
    Operator<?> op = genSelectPlan(dest, selExprList, qb, input, inputForSelectStar, false);

    LOG.debug("Created Select Plan for clause: {}", dest);

    return op;
  }
Returns whether the pattern is a regex expression (instead of a normal
string). Normal string is a string with all alphabets/digits and "_".
ql/src/java/org/apache/hadoop/hive/ql/parse/SemanticAnalyzer.java