Tracking Issue for titlecase handling in `core::char`

Feature gate: #![feature(titlecase)]

This is a tracking issue for library functions to handle title-casing of Unicode characters.

Public API

// core

impl char {
    pub fn is_cased(self) -> bool;
    pub fn case(self) -> Option<CharCase>;
    pub fn is_titlecase(self) -> bool;
    pub fn to_titlecase(self) -> ToTitlecase;
}

mod char {
    #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)]
    pub enum CharCase {
        Lower = 0b00,
        Title = 0b10,
        Upper = 0b11,
    }

    struct ToTitlecase { ... }
    impl Iterator for ToTitlecase { ... }
    impl DoubleEndedIterator for ToTitlecase { ... }
    impl FusedIterator for ToTitlecase { }
    impl ExactSizeIterator for ToTitlecase { ... }
    impl fmt::Display for ToTitlecase { ... }
}

// alloc

impl str {
    fn word_to_titlecase(&self) -> String;
}

Steps / History

(Remember to update the S-tracking-* label when checking boxes.)

• ACP: https://github.com/rust-lang/libs-team/issues/354
• Implementation: #122668 https://github.com/rust-lang/rust/pull/154288 https://github.com/rust-lang/rust/pull/155705
• Final comment period (FCP)^1
• Stabilization PR

Unresolved Questions

• None yet.

Start with the proposed APIs in core::char and alloc::str, then review implementation PRs #154288 and #155705. The remaining checklist items are the final comment period and stabilization PR; done means the feature has completed that process and is stabilized.