*
     */
    public Symbol parse(String expression, int lineNumber) throws Exception {
        try {
            _expression = expression;
            _lineNumber = lineNumber;
            return super.parse();
        }
        catch (IllegalCharException e) {
            ErrorMsg err = new ErrorMsg(ErrorMsg.ILLEGAL_CHAR_ERR,
                                        lineNumber, e.getMessage());
            _parser.reportError(Constants.FATAL, err);
        }
        return null;
    }