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Rollup merge of #99454 - benluelo:control-flow/continue-combinators, r=scottmcm

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Add map_continue and continue_value combinators to ControlFlow

As suggested in this comment: https://github.com/rust-lang/rust/issues/75744#issuecomment-1188549494

Related tracking issue: https://github.com/rust-lang/rust/issues/75744

r? ``````@scottmcm``````
This commit is contained in:
Matthias Krüger 2022-07-21 18:42:04 +02:00 committed by GitHub
commit 9610c71b1e
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35
library/core/src/ops/control_flow.rs
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@ -195,6 +195,41 @@ impl<B, C> ControlFlow<B, C> {
ControlFlow::Break(x) => ControlFlow::Break(f(x)),
}
}
/// Converts the `ControlFlow` into an `Option` which is `Some` if the
/// `ControlFlow` was `Continue` and `None` otherwise.
///
/// # Examples
///
/// ```
/// #![feature(control_flow_enum)]
/// use std::ops::ControlFlow;
///
/// assert_eq!(ControlFlow::<i32, String>::Break(3).continue_value(), None);
/// assert_eq!(ControlFlow::<String, i32>::Continue(3).continue_value(), Some(3));
/// ```
#[inline]
#[unstable(feature = "control_flow_enum", reason = "new API", issue = "75744")]
pub fn continue_value(self) -> Option<C> {
match self {
ControlFlow::Continue(x) => Some(x),
ControlFlow::Break(..) => None,
}
}
/// Maps `ControlFlow<B, C>` to `ControlFlow<B, T>` by applying a function
/// to the continue value in case it exists.
#[inline]
#[unstable(feature = "control_flow_enum", reason = "new API", issue = "75744")]
pub fn map_continue<T, F>(self, f: F) -> ControlFlow<B, T>
where
F: FnOnce(C) -> T,
{
match self {
ControlFlow::Continue(x) => ControlFlow::Continue(f(x)),
ControlFlow::Break(x) => ControlFlow::Break(x),
}
}
}
/// These are used only as part of implementing the iterator adapters.