The approach I'm working on uses the same "growing the seed" idea, but in a different way. It involves the memo entries being able to remember which left-recur

The approach I'm working on uses the same "growing the seed" idea, but in a different way. It involves the memo entries being able to remember which left-recursive results they are dependent on. This way, when a left-recursive rule produces a result that is dependent on itself, it knows that this match can possibly be "grown" through repeated iterations. That's a basic sketch of the idea. Performance properties remain the same in the case of left-recursive rules that are not interdependent. I don't really know what they are like for large numbers of interdependent left-recursive rules--but if you have a language like that, better to use an Earley or GLR parser. I'm still working on it. It passes a battery of test cases, two of which I posted above, but I'm not 100% confident in it just yet. Also, as posted above, I'm trying to get permission from the higher-ups to release the code into the wild.