They exist. In fact, if you hand Rust's regex engine the pattern ` |\r|\n`, then it will compile it down to a very simple alternation of three literal bytes. It will never touch the actual regex engine at all. Once the regex engine knows its a simple alternation of three bytes, it will actually use a variant of memchr called memchr3[1], which looks almost exactly like the OP's "portable" approach.

So it's not quite the fastest possible because it doesn't use SIMD, but this is mostly because we don't have good explicit SIMD support on stable Rust yet. Once we do, this immediately becomes a strong candidate to optimize to something like the OP's fastest version (and also probably generalizing to AVX2 instructions as well).

N.B. My sibling comment linked to my blog post on ripgrep, which uses Rust's regex engine. ;-)

[1] - https://github.com/BurntSushi/rust-memchr/blob/master/src/li...

Awesome, thank you!

You might checkout the literal optimizations that ripgrep does. IIRC, the underlying regex lib is optimizing a few classes of "simple" regexes with SIMD to achieve better perf than the first handwritten code in that article.

http://blog.burntsushi.net/ripgrep/#literal-optimizations

Time to break out the HDL then...

http://www.braketlogic.com/