Should a NimbleParsec parser hang?

I have seen it hang if I wrote a parser that would infinitely recurse. Unfortunately I can’t recall the details, but I fixed it by changing my parser. If you can’t find any infinite recursion happening, it might be a bug in NimbleParsec?

Anyway, if you want to guard against the parser hanging, you might want to wrap the parsing in a Task

Yes, it can loop forever. Usually the culprit is repeat. Its docs has warnings on when such cases may happen:

If you are still running into loops, then a minimal parser that reproduces the failure would be welcome.

Thank you Jose.

I had read that but hadn’t appreciated what it was saying. I do have a few cases where repeat and optional get combined and I suspect this is what is happening.

Part of the problem is that I find my error handling strategy is “fiddle with it a bit” because I find the error information difficult to work with. Any guidance about (or good examples of) that would be much appreciated.

Thanks.

Matt

As a further note here, in the (much simpler) parser combinator library I built called Ergo I have implemented cycle detection and the parser will automatically halt with a trace of the history of rules. A bit primitive right now but I’ve found it useful when playing with a new grammar.