add unicode case folding for char/str

[steveklabnik]

Issue by thestinger
Monday Sep 09, 2013 at 19:10 GMT

For earlier discussion, see rust-lang/rust#9084

This issue was labelled with: A-libs, A-unicode, I-enhancement in the Rust repository

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[Centril]

triage: @clarcharr whatever happened to your PR and is this issue still relevant?

[clarfonthey]

@Centril I never finished my PR and it's still relevant. Not sure if I'll be able to get to this any time soon.

[crlf0710]

There is https://github.com/unicode-rs/rust-caseless/ now. Maybe this can just be closed @Centril

[clarfonthey]

Honestly? Not really.

I feel that adding methods to obtain the case-folded forms of characters and strings to the standard library would be useful. The main justification is that uppercase/lowercase mappings are included, and not having a case-folding option means that many are likely to simply implement case-folding wrong because it would otherwise require adding an additional crate.

These methods don't have to be particularly robust, just, I feel that having the tables available would be good. Crates like caseless still have a use case for providing things like case-insensitive matching, which this would not solve.

[Ralith]

If they're not robust, then the objective of preventing people from doing it wrong would be actively undermined.

…

On Tue, Oct 29, 2019, 16:37 Clar Fon ***@***.***> wrote: Honestly? Not really. I feel that adding methods to obtain the case-folded forms of characters and strings to the standard library would be useful. The main justification is that uppercase/lowercase mappings are included, and not having a case-folding option means that many are likely to simply implement case-folding wrong because it would otherwise require adding an additional crate. These methods don't have to be particularly robust, just, I feel that having the tables available would be good. Crates like caseless still have a use case for providing things like case-insensitive matching, which this would not solve. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#791?email_source=notifications&email_token=AAAZQ3RQN2BO2Y2D2LG2NG3QRDCKRA5CNFSM4A3JGR6KYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOECSN47A#issuecomment-547675772>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAAZQ3QFACNESSKWO7LMLNTQRDCKRANCNFSM4A3JGR6A> .

[clarfonthey]

Honestly, I disagree, but mostly because I didn't clarify what I meant by "not particularly robust."

If you want 100% correctness you need to use locales, but Rust offers tools to do locale-agnostic operations. For example, str supports code-point-based comparisons even though technically you should be comparing based upon locales. I feel that case folding is a welcome addition.