generate less code for regex plugin about regex HOT 8 CLOSED

@huonw I'm not sure this issue actually belongs on this repo, unless there is something about the regex! implementation that is abusing code generation?

from regex.

I don't know the specifics of regex!, so it may very well be better suited to being returned to rust-lang/rust. (I assume the migration was mechanical.)

from regex.

(Yup, was mechanical.) OK, I re-opened the issue on rust-lang/regex, but I'm also keeping this open because it would be nice to reduce the amount of code generated by regex! (which I think is one way of attacking the original problem).

from regex.

I wonder if const fn allows for abstracting some of the code away. (That said, const fn can't do much computation so I guess it can't.)

from regex.

Yeah, I doubt const fn would help (I read the original RFC long ago, not sure if it got more powerful since then). I think the real key to this will be two-fold:

1. Do more analysis on the regex and generate cleverer code (like Ragel does and like OP's example).
2. Stop embedding full NFA and fall back to the dynamic implementation. (There is not much difference between them now after recent perf improvements in the dynamic impl. regex! used to be better because it allocated less, but it no longer has that advantage!)

from regex.

What is the code generated?

from regex.

@arielb1 Right now, it's a full NFA simulation. The generator requires calling the regex parser and compiler before hand.

from regex.

Closing in favor of #26.

from regex.