private ASTNode getNodeReplacementforDefault(String newValue) throws SemanticException {
    ASTNode newNode = null;
    if(newValue== null) {
      newNode = ASTBuilder.construct(HiveParser.TOK_NULL, "TOK_NULL").node();
    }
    else {
      try {
        newNode = new ParseDriver().parseExpression(newValue);
      } catch(Exception e) {
        throw new SemanticException("Error while parsing default value for DEFAULT keyword: " + newValue
                                        + ". Error message: " + e.getMessage());
      }
    }
    return newNode;
  }
Constructs an AST for given DEFAULT string
@param newValue
@throws SemanticException
ql/src/java/org/apache/hadoop/hive/ql/parse/SemanticAnalyzer.java