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change the order of type arguments on ControlFlow

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This allows ControlFlow<BreakType> which is much more ergonomic for
common iterator combinator use cases.
This commit is contained in:
Leonora Tindall
2020-09-11 16:36:58 -05:00
committed by Scott McMurray
parent a9cd294cf2
commit 84daccc559
5 changed files with 18 additions and 25 deletions
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12
library/core/src/ops/control_flow.rs
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@@ -3,7 +3,7 @@ use crate::ops::Try;
/// Used to make try_fold closures more like normal loops
#[unstable(feature = "control_flow_enum", reason = "new API", issue = "75744")]
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum ControlFlow<C, B> {
pub enum ControlFlow<B, C = ()> {
/// Continue in the loop, using the given value for the next iteration
Continue(C),
/// Exit the loop, yielding the given value
@@ -11,7 +11,7 @@ pub enum ControlFlow<C, B> {
}
#[unstable(feature = "control_flow_enum", reason = "new API", issue = "75744")]
impl<C, B> Try for ControlFlow<C, B> {
impl<B, C> Try for ControlFlow<B, C> {
type Ok = C;
type Error = B;
#[inline]
@@ -31,7 +31,7 @@ impl<C, B> Try for ControlFlow<C, B> {
}
}
impl<C, B> ControlFlow<C, B> {
impl<B, C> ControlFlow<B, C> {
/// Returns `true` if this is a `Break` variant.
#[inline]
#[unstable(feature = "control_flow_enum", reason = "new API", issue = "75744")]
@@ -58,7 +58,7 @@ impl<C, B> ControlFlow<C, B> {
}
}
impl<R: Try> ControlFlow<R::Ok, R> {
impl<R: Try> ControlFlow<R, R::Ok> {
/// Create a `ControlFlow` from any type implementing `Try`.
#[unstable(feature = "control_flow_enum", reason = "new API", issue = "75744")]
#[inline]
@@ -80,7 +80,7 @@ impl<R: Try> ControlFlow<R::Ok, R> {
}
}
impl<B> ControlFlow<(), B> {
impl<B> ControlFlow<B, ()> {
/// It's frequently the case that there's no value needed with `Continue`,
/// so this provides a way to avoid typing `(())`, if you prefer it.
///
@@ -102,7 +102,7 @@ impl<B> ControlFlow<(), B> {
pub const CONTINUE: Self = ControlFlow::Continue(());
}
impl<C> ControlFlow<C, ()> {
impl<C> ControlFlow<(), C> {
/// APIs like `try_for_each` don't need values with `Break`,
/// so this provides a way to avoid typing `(())`, if you prefer it.
///