grmtools

I decided to look; just found these: chumsky (parser combinator): https://github.com/zesterer/chumsky LALRPOP (LR(1)): https://github.com/lalrpop/lalrpop grmtools (YACC) https://github.com/softdevteam/grmtools/ re: Other parsers: https://softdevteam.github.io/grmtools/master/book/othertool... antlr4rust: https://github.com/rrevenantt/antlr4rust

In rust I really like the grmtools set of tools: https://github.com/softdevteam/grmtools. It is lexx/yacc style lexer and parser generation and generates an LR1 parser but using the CPCT+ algorithm for error recovery. Iirc the way it works is that when an error occurs, the nearest likely valid token is inserted, the error is recorded and parsing continues. I would use this for anything that is simple enough and recursive descent for anything more complicated and where even more context is needed for errors.

Alas, most parser generators don't have very good error recovery (and some have such terrible error recovery that I think it's worse than not having any!). It turns out that this isn't inevitable: there's been a long strand of research on decent error recovery for LR parsers, at least, but it needed a bit of a refresh to be practical. If you'll forgive the blatant self promotion, we tackled this problem in https://soft-dev.org/pubs/html/diekmann_tratt__dont_panic/ which is implemented in our Rust parsing system https://github.com/softdevteam/grmtools/. It won't beat the very best hand-written error recovery routines, but it's often not far behind.

> The problem with yacc/bison-style LALR parser generators is that you end up with an LALR parser. Which works great on syntactically correct code, but trying to get a reasonable error message out of one is about as much fun as repeatedly poking yourself in the eye with a sharp stick. The standard ways of getting error messages from LR parsers are pretty bad, but there is a long line of work that's tried to make it better. If you'll forgive the immodesty on my part, I've been working on updating and fixing that work. There's a draft paper at https://arxiv.org/abs/1804.07133 and a beta-ish implementation at https://github.com/softdevteam/grmtools/, so you can see what you think! [EDIT: fixed formatting]