• v1 - https://github.com/ncellar/autumn_v1

The initial version of Autumn is an extensible parser-combinator library built upon the PEG formalism. It was the first general PEG parsing library to support left recursion with both left- and right-associative interpretations. It also includes support for precedence and associativity.

It was the object of a paper (Parsing Expression Grammars Made Practical) at the SLE (Software Language Engineering) in 2015.

• v2 - https://github.com/ncellar/autumn_v2

v2 is a considerably simplified rewrite of v1 in the Kotlin programming language.

It was the object of a paper (Taming Context-Sensitive Languages with Principled Stateful Parsing) at the SLE (Software Language Engineering) in 2016.

• v3 - https://github.com/ncellar/whimsy

v3 is a rewrite of v2, still in Kotlin. It was part of the Whimsy compiler framework project, whose other component (a reactive middle-end compiler library) never fuly materialized.

v3 features two significant changes: first the context-sensitive parsing mechanism now uses a log of undoable changes instead of relying on state snapshots. Second, the framework uses Kotlin's inline keyword pervasively in order to avoid megamorphic call sites overheads, and enable additional optimization. This works well in practice, and performance are greatly improved.

• v4 - https://github.com/norswap/autumn

The current (and hopefully final major revision) of Autumn.

This version underpins my 2019 PhD thesis.

This is a full rewrite in Java. It keeps v3's way of handling the context, but reverts back to using a graph of parser objects to represent a grammar — the reason being that these graphs can be traversed by walkers and visitors to achieve all kind of things.

It adds many many useful features, and performance are on par with v3 despite the lack of inlining. The best Autumn has to offer!