Principled Procedural Parsing (2019) [pdf]

There is even an explicit section 1.6 "Overview & Contributions", but it's still difficult to discern what specific, scientific contributions were made in this dissertation. The most fruitful place to find clues is in the last paragraph on page 21 which mentions the previous publications “Parsing Expression Grammars Made Practical”, “Taming Context-sensitive Languages with Principled Stateful Parsing” and "Procedural Shift-Reduce Parsing”. So we would probably have to read these papers as well to find out what contribution is supposed to have been made here.

Unmatched in the land of Java. AFAICT from the examples it looks comparable to LPeg in usage and feature set. Unsurprisingly, its based on PEGs according to the documentation.

AFAICT, Autumn seems to support some kinds of memoization as a performance enhancement, and has a utility routine to synthesize left-associative rules. But LPeg has match-time captures which let you build context-sensitive grammars inline, such as for ubiquitous TLV (tag-value-length) formats. In terms of sheer utility the latter is far more powerful, IMO.

Nonetheless, Autumn is definitely one of the better parser combinators I've seen. Both Autumn and LPeg stand out because of how easy they make it to specify inline transformations. Most parser combinators make it easy to match and generate an AST, but you're literally given a raw match tree that you then need to transform into a data structure usable in your program. Not difficult, but neither is hand-rolling a parser. The point of combinators is to make this stuff easier and more declarative. Autumn (AFAICT) and LPeg actually help to simplify the other 50% of the work, not just the first 50%.

There also appears to be a rust version.

https://github.com/xurtis/autumn

Did you mean LL(1/k) and not LR? Looking at the site it was mentioning ll parsers