Hacker News Reader

Sorry, finished the post just now with more comparisons on other inputs

The reason is just that the normal mode is faster in average non pathological cases

Could you have a heuristics based on the input size and the pattern to decide what to use?

Yes, this is entirely possible. you can even explore the automaton eagerly and detect if it's possible to loop from an accepting state to a nonaccepting one.

Exciting stuff for future work

Ripgrep does something like thhis. It has a meta regex engine that switches engine when it finds what looks like pathological cases (or rather, the regex-automata crate does, which is used by the regex crate, which powers ripgrep).

https://docs.rs/regex-automata/latest/regex_automata/meta/st...

Ripgrep in turn exposes some knobs to tweak the heuristics

https://github.com/BurntSushi/ripgrep/blob/master/FAQ.md#how...

Reply on news.ycombinator.com