fancy-regex VS cw

https://github.com/fancy-regex/fancy-regex/issues/84 it's still open issue

Ahh, very interesting, thanks for sharing! Do you have any thoughts around why that is? I presume that's due to Oniguruma supporting a much broader feature set and something like fancy-regexp's approach with mixing a backtracking VM and NFA implementation for simple queries would be needed for better perf? (I am aware you played a role in that) [1]

I have been playing around with regex parsing through building parsers through parser combinators at runtime recently, no clue how it will perform in practice yet (structuring parser generators at runtime is challenging in general in low-level languages) but maybe that could pan out and lead to an interesting way to support broader sets of regex syntaxes like POSIX in a relatively straightforward and performant way.

[1] https://github.com/fancy-regex/fancy-regex#theory

Not an expert but fancy regex is a Rust library that uses a hybrid approach to detect whether a sub expression contains backtracking and delegates to the appropriate engine.

https://github.com/fancy-regex/fancy-regex

For things that are commonly and almost-ideally represented as text files, there’s a lot of Rust based alternatives are faster and have more features than the old unix/GNU tools: ripgrep, fd, cw, and you can find more in this list.

Nice, beats my old Rust wc through sheer brute force on my old 12c/24t server:

A lot of unix-y tools have been rewritten in rust, where the usefulness comes from it being faster or having more features. Examples: bat, cw, lsd, ripgrep, diskonaut, gping. Maybe you could find an interesting program to rewrite?

cw, an optionally-multithreaded bytecount-accelerated wc clone

Having written a Rust wc implementation a few years ago (https://github.com/Freaky/cw), I had a look at theirs.

It's pretty naive - a simple linewise read_until loop, a conditional to avoid word splitting and such if it's not needed, and for some reason it collects results into an array and prints when it's done rather than printing as it goes.

It doesn't support --files0-from like GNU wc, so isn't a drop-in replacement from that perspective. It also has the sadly common Rust trope of only supporting filenames that are valid UTF-8.

It doesn't seem overly slow considering its simplicity - usually trading blows with GNU and BSD wc. Perhaps the most glaring omission is the lack of a fast path for -c, which should reduce to a stat() call. Also unfortunate not to use the excellent bytecount crate to provide a very fast -l/m path.

The read_until loop also makes its memory use unpredictable compared with other wc's. If you run it on /dev/zero it will try to eat your computer.