code: protected Long eval(final Object... _values)
      {
          final Long ret;
  
          if (_values == null || _values.length == 0 || _values[0] == null)  {
              ret = null;
          } else if (_values[0] instanceof String && !"".equals(_values[0])) {
              ret = Long.parseLong((String) _values[0]);
          } else if (_values[0] instanceof Number) {
              ret = ((Number) _values[0]).longValue();
          } else  {
              ret = null;
          }
  
          return ret;
      }
docs: Evaluate the value.
  @param _values value to be evaluated
  @return Long value