Move `Utf8Chunks::new` to be inherent on `[u8]`

[dylni]

Proposal

Problem statement

Utf8Chunks::new requires importing Utf8Chunks. Adding this method on [u8] would allow it to be used without an import.

This API is unstable, so this is not a breaking change.

Motivation, use-cases

This is similar to other methods treating [u8] as a byte string, such as <[u8]>::is_ascii.

Example

Code using Utf8Chunks::new:

use std::str::Utf8Chunks;

for chunk in Utf8Chunks::new(string) {
    let valid = chunk.valid();
    let invalid = chunk.invalid();
    // formatting for `valid` and `invalid`
}

Code using <[u8]>::utf8_chunks:

for chunk in string.utf8_chunks() {
    let valid = chunk.valid();
    let invalid = chunk.invalid();
    // formatting for `valid` and `invalid`
}

Solution sketches

Current signature:

impl<'a> Utf8Chunks<'a> {
    fn new(bytes: &'a [u8]) -> Self;
}

Proposed signature:

impl [u8] {
    fn utf8_chunks(&self) -> Utf8Chunks<'_>;
}

Links and related work

• Tracking issue: Tracking Issue for utf8_chunks rust#99543
• Proposal: Expose Utf8LossyChunksIter #54
• Implementation: Expose Utf8Lossy as Utf8Chunks rust#99544

What happens now?

This issue is part of the libs-api team API change proposal process. Once this issue is filed the libs-api team will review open proposals in its weekly meeting. You should receive feedback within a week or two.

[dtolnay]

Looks good. This would join quite a few other byte-string-like methods we already have on [u8].

• https://doc.rust-lang.org/std/primitive.slice.html#method.is_ascii
• https://doc.rust-lang.org/std/primitive.slice.html#method.eq_ignore_ascii_case
• https://doc.rust-lang.org/std/primitive.slice.html#method.make_ascii_uppercase
• https://doc.rust-lang.org/std/primitive.slice.html#method.make_ascii_lowercase
• https://doc.rust-lang.org/std/primitive.slice.html#method.escape_ascii
• https://doc.rust-lang.org/std/primitive.slice.html#method.to_ascii_uppercase
• https://doc.rust-lang.org/std/primitive.slice.html#method.to_ascii_lowercase
• https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.as_ascii (unstable)
• https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.as_ascii_unchecked (unstable)
• https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.trim_ascii_start (unstable)
• https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.trim_ascii_end (unstable)
• https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.trim_ascii (unstable)