See the nearby comment by adwn: aggressive "packrat" caching fixates on long matches starting at intermediate positions, without considering any shortest matche

See the nearby comment by adwn: aggressive "packrat" caching fixates on long matches starting at intermediate positions, without considering any shortest matches at the same position. Correct parsing would require discarding these long matches because they cause higher level rule expansions to fail, but smarter algorithms with an increase of runtime due to complete backtracking and/or an increase of memory usage to distinguish and remember different matches for the same rule at the same location would be required. EDIT: two nearby comments by adwn.