public IEnumerator <EventBean> GetEnumerator(Viewable parent)
        {
            if (!_prototype.IsHistoricalOnly)
            {
                return(ObtainEnumerator(parent));
            }

            ResultSetProcessorUtil.ClearAndAggregateUngrouped(_exprEvaluatorContext, _aggregationService, parent);
            ArrayDeque <EventBean> deque = ResultSetProcessorUtil.EnumeratorToDeque(ObtainEnumerator(parent));

            _aggregationService.ClearResults(_exprEvaluatorContext);
            return(deque.GetEnumerator());
        }