smartstring VS regex

Your use case sounds like it will involve a lot of small strings that use a subset of UTF-8. If you’re concerned about performance, you could look into something like smartstring. Sixbit also looks interesting, but it looks like it won’t give you any more characters and it’d probably require additional computation to do the conversion (and they’d have to be converted back out).

> If you have a long-running async function, then pass parameters by value! If you have a polymorphic async function, then return your result in a Box.

I've taken to making heavy use of the smallvec and smartstring crates for this. Most lists and strings are small in practice. Using smallvec / smartstring lets you keep most clone() calls allocation-free. This in turn lets you use owned objects, which are easier to reason about - for you and the borrow checker. And you keep a lot of the performance of just passing around references.

I tried to use async rust a couple of years ago, and fell on my face in the process. Most of my rust at the moment is designed to compile to wasm - and then I'm leaning on nodejs for networking and IO. Writing async networked code is oh so much easier to reason about in javascript. When GAT, TAIT and some other language features to fix async land I'll muster up the courage to make another attempt. But rust's progress at fixing these problems feels painfully slow.

https://crates.io/crates/smallvec / https://crates.io/crates/smartstring

Just to point out, smartstring no longer assumes String memory layout. From the changelog:

There's some really good crates that implement SSO floating around - eg, SmartString. But I agree - its a pity they're needed. Swift built this into the core string type in the language. I think that was the right call.

Comparatively: * SmolStr can inline up to 22 bytes but does not adjust down for 32-bit architectures, meaning it's potentially wasting memory on 32-bit archs. Similarly though it's immutable and Clone is O(1) * SmartString can inline up to 23 bytes, but it's mutable and Clone is O(n). Also this crate makes assumptions about the memory layout of a String, which in theory should be fine, but is a slight caveat.

SmartString is used to store identifiers (which tends to be short, fewer than 23 characters, and ASCII-based) because they can usually be stored inline. Map keys now also use SmartString.

I’ve been using smartstrings, which is both excellent and maintained. https://github.com/bodil/smartstring

The homepage has a benchmark that compares Zed's "insertion latency" to other editors, and this is the description:

> Open input.rs at the end of line 21 in rust-lang/regex. Type z 10 times, measure how long it takes for each z to display since hitting the z key.

Could someone clarify what that means? My interpretation of that was to go to https://github.com/rust-lang/regex/blob/master/regex-cli/arg... and start typing 'z' at the end of line 21, but that doesn't seem to make any sense. I guess that repo got refactored and those instructions are out of date?

We also used the avenue to sluggify the question title. We used regex to fish out and replace all occurrences of punctuation and symbol characters with an empty string and using the itertools crate, we joined the words back together into a single string, where each word is separated by a hyphen ("-").

Command-Line Rust taught me how to use crates like clap, assert_cmd, and regex. I felt lost before because I didn't know about Rust's ecosystem--which is arguably as important as the language itself. Also, looking up and comparing libraries is a tiring task! blessed.rs is nice but Command-Line Rust really saved me from analysis paralysis.

burntsushi actually regrets making regex replace return a Cow: https://github.com/rust-lang/regex/issues/676#issuecomment-6.... I’m glad it does, and wish it took an impl Into> there, for the reasons discussed in the issue, but burntsushi has a lot more experience of the practical outcomes of this. Just something more to think about.

I'm not familiar with the AoC problem. You might be able to. But RegexSet doesn't give you match offsets.

You can drop down to regex-automata, which does let you do multi-regex search and it will tell you which patterns match[1]. The docs have an example of a simple lexer[2]. But... that will only give you non-overlapping matches.

You can drop down to an even lower level of abstraction and get multi-pattern overlapping matches[3], but it's awkward. The comment there explains that I had initially tried to provide a higher level API for it, but was unsure of what the semantics should be. Getting the starting position in particular is a bit of a wrinkle.

[1]: https://docs.rs/regex-automata/latest/regex_automata/meta/in...

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

[3]: https://github.com/rust-lang/regex/blob/837fd85e79fac2a4ea64...

It’s not quite that simple, but folks are working on it.

https://github.com/rust-lang/regex/issues/425#issuecomment-1...

https://github.com/helix-editor/helix/pull/211#issuecomment-...

Dependencies used: - regex - unicode_reader - rust decimal - tokio

https://www.cs.princeton.edu/courses/archive/fall19/cos226/l... and https://kean.blog/post/lets-build-regex are excellent introductions to implementing a (very) simplified regex engine: construct a nondetermistic finite state automaton for the regex, then perform a graph search on the resulting digraph; if the vertex corresponding to your end state is reachable, you have a match.

I think this exercise is valuable for anyone writing regexes to not only understand that there's less magic than one might think, but also to visualize a bunch of balls bouncing along an NFA - that bug you inevitably hit in production due to catastrophic backtracking now takes on a physical meaning!

Separately re: the OP, https://github.com/rust-lang/regex/issues/822 (and specifically BurntSushi's comment at the very end of the issue) adds really useful context to the paragraph in the OP about niche APIs: https://blog.burntsushi.net/regex-internals/#problem-request... - searching with multiple regexes simultaneously against a text is both incredibly complex and incredibly useful, and I can't wait to see what the community comes up with for this pattern!