Using generics for bytes / code units / code points

[annevk]

See #1 for some discussion on code units.

A term like "ASCII digit" and others like it are equally meaningful for all three primitives, since the primitives are defined as integers. Should we define these terms as generics so they can apply to each primitive?

Alternative we could change the phrasing, e.g., "An ASCII digit is a byte, code unit, or code point in the range 0x30 to 0x39, inclusive." This would also require slight tweaking of how we define "byte" and "code point".

[domenic]

Currently they only operate on code points, I see.

I guess I would like to see any changes here motivated by usage. I am sure such usage exists but it would help make things clearer.

[annevk]

https://mimesniff.spec.whatwg.org/#parsing-a-mime-type tries to use the term ASCII whitespace on bytes. We might even have to define a MIME type parser both for byte sequences and strings, but not sure about that. Would require some more investigation as to what user agents actually do with all the various MIME type entry points.

[annevk]

In whatwg/html#2471 I found a couple places where HTML could have used a generic "ASCII whitespace" as well. We could just define "byte whitespace" I suppose and use that.

[annevk]

More arguments for generics: URL splits a byte sequence in https://url.spec.whatwg.org/#concept-urlencoded-parser.

[annevk]

Perhaps though that can be refactored into doing decoding into a string first.

[annevk]

I'm pretty happy to use isomorphic decode/encode and their underlying technique as documented by 88fa454 instead of having this. Happy to reconsider if this remains a common need somewhere though.