bstr VS nomicon

Libraries for a lot of this stuff exist (albeit in many cases not very mature yet):

- https://github.com/pop-os/cosmic-text does text layout (which Taffy explicitly considers out of scope)

- https://github.com/AccessKit/accesskit does accessibility

- https://github.com/servo/rust-cssparser does value-agnostic CSS parsing (it will parse the general syntax but leaves value parsing up to the user, meaning you can easily add support for whatever properties you what). Libraries like https://github.com/parcel-bundler/lightningcss implement parsing for the standard css properties.

- There are crates like https://github.com/BurntSushi/bstr and https://docs.rs/wtf8/latest/wtf8/ for working with non-unicode text

We are planning to add a C API to Taffy, but tbh I feel like C is not very good for this kind of modularised approach. You really want to be able to expose complex APIs with enforced type safety and this isn't possible with C.

As the author of bstr and also the regex implementation that bstr uses to implement word breaking, it is linear time.

NSFL: https://github.com/BurntSushi/bstr/blob/86947727666d7b21c97e...

OsStr uses WTF-8 on Windows, and just represents the raw underlying bytes on Unix.

Byte strings can be WTF-8. They can be anything. The problem is that there is no real way to (easily) get the underlying WTF-8 bytes of an OsStr on Windows. So there's no free conversion to and from byte strings.

I wrote more about this in the bstr docs (and don't miss the link to os_str_bytes): https://docs.rs/bstr/latest/bstr/#file-paths-and-os-strings

I'd be happy to answer more questions if you have them. :-) https://github.com/BurntSushi/bstr/discussions

Check out bstr, which does this exact thing for its BString and BStr types.

Currently slated for next Monday: https://github.com/BurntSushi/bstr/issues/40

This is just an FYI. I don't mean to say much to your overall point, although, as someone else who has spent a lot of time doing Unicode-y things, I do tend to agree with you. I had a very similar discussion a bit ago.[1]

Putting that aside, at least with respect to grapheme segmentation, it might be a little simpler than you think. But maybe only a little. The unicode-segmentation crate also does word segmentation, which is quite a bit more complicated than grapheme segmentation. For example, you can write a regex to parse graphemes without too much fuss[2]. (Compare that with the word segmentation regex, much to my chagrin.[3]) Once you build the regex, actually using it is basically as simple as running the regex.[4]

Sadly, not all regex engines will be able to parse that regex due to its use of somewhat obscure Unicode properties. But the Rust regex crate can. :-)

And of course, this somewhat shifts code size to heap size. So there's that too. But bottom line is, if you have a nice regex engine available to you, you can whip up a grapheme segmenter pretty quickly. And some regex engines even have grapheme segmentation built in via \X.

[1]: https://github.com/BurntSushi/aho-corasick/issues/72

[2]: https://github.com/BurntSushi/bstr/blob/e38e7a7ca986f9499b30...

[3]: https://github.com/BurntSushi/bstr/blob/e38e7a7ca986f9499b30...

[4]: https://github.com/BurntSushi/bstr/blob/e38e7a7ca986f9499b30...

This is a great idea. I realize the find implementation is not ideal and have considered bringing in an optional dependency to improve performance. I remembered bstr using two-way search, so I was wondering if depending on the full crate for searching would be worthwhile, but I see that changed. Thanks for the tip!

Fun little nit-pick that does not detract from your overall point: you can actually count graphemes with a regex and that's exactly what bstr does. :-)

it’s even written by the same person that wrote the Nomicon (the guide to the dark arts of unsafe)

If you want to dive deeper you can always have other options but now there are concrete cases, if you want to do low level thing https://doc.rust-lang.org/nomicon/ while if you want multi thread/concurrency stuff https://marabos.nl/atomics/ . There are many many books so you will have to point yourself to what you want

Nonononono. SeqCst is the most error prone memory order: https://github.com/rust-lang/nomicon/issues/166

Hope this helps. For more details, see the Rustonomicon. I referenced the subtyping chapter here extensively.

Nice video! Glad I could help out. This stuff is hard, and I'm still learning a lot about it myself even years later. The Rustonomicon is a great read if you haven't already.

Have you got a moment to read through the good book , after reading through this perhaps try the Rustonomicon.

That is not what UB means. Undefined Behaviour is behaviour that the compiler is allowed to assume will never happen, and which can consequently cause miscompilations due to optimisation passes gone wrong if it does in fact occur in the source code.

It's true that Rust does not have a written specification that clearly delineates what is and isn't UB in a single place. But:

1. UB is impossible in safe code (modulo bugs in unsafe code)

2. There are resources such as the Rustinomicon (https://doc.rust-lang.org/nomicon/) that provide a detailed guide on what is and isn't allowed in unsafe code.

In practice, it's much easier to avoid UB in Rust than it is in C++.

However, this is a wide topic out of scope for a Reddit comment, so maybe just read the Rustonomicon. It explains everything about data handling in Rust.

The ownership model & borrow checker makes rust a bit of an awkward language in which to write complex data structures like trees and graphs. It can be done - since you can always use raw pointers & unsafe code when you absolutely need to to treat rust like C. But the language fights you, and the community can get a bit moralistic about this sort of thing. The rust nomicon is a fantastic resource for learning the limits of the borrow checker, and where and how to use unsafe code correctly. You will need unsafe less than you think you will, but sometimes you will have no choice.