Tracking Issue for `peekable_next_if_map`

[kennytm]

Feature gate: #![feature(peekable_next_if_map)]

This is a tracking issue for the std::iter::Peekable::next_if_map{_mut} functions, as a combination of next_if() and transformation in a single step (ACP: rust-lang/libs-team#613).

Public API

impl<I: Iterator> Peekable<I> {
    pub fn next_if_map<R>(
        &mut self,
        f: impl FnOnce(I::Item) -> Result<R, I::Item>,
    ) -> Option<R>;

    pub fn next_if_map_mut<R>(
        &mut self,
        f: impl FnOnce(&mut I::Item) -> Option<R>,
    ) -> Option<R>;
}

Steps / History

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

• Implementation: core: add Peekable::next_if_map #143725
• Final comment period (FCP)¹
• Stabilization PR

Unresolved Questions

• In the ACP a by-ref version ((&mut self, impl FnOnce(&I::Item) -> Option<R>) -> Option<R>) was also proposed. Whether the by-ref version is needed?

Footnotes

1. https://std-dev-guide.rust-lang.org/feature-lifecycle/stabilization.html ↩