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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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3
compiler/rustc_data_structures/src/graph/iterate/mod.rs
View file

@ -87,8 +87,7 @@ where
} }
/// Allows searches to terminate early with a value. /// Allows searches to terminate early with a value.
// FIXME (#75744): remove the alias once the generics are in a better order and `C=()`. pub use std::ops::ControlFlow;
pub type ControlFlow<T> = std::ops::ControlFlow<(), T>;
/// The status of a node in the depth-first search. /// The status of a node in the depth-first search.
/// ///

10
library/core/src/iter/adapters/mod.rs
View file

@ -1280,7 +1280,7 @@ where
#[inline] #[inline]
fn find<T, B>( fn find<T, B>(
f: &mut impl FnMut(T) -> Option<B>, f: &mut impl FnMut(T) -> Option<B>,
) -> impl FnMut((), T) -> ControlFlow<(), B> + '_ { ) -> impl FnMut((), T) -> ControlFlow<B> + '_ {
move |(), x| match f(x) { move |(), x| match f(x) {
Some(x) => ControlFlow::Break(x), Some(x) => ControlFlow::Break(x),
None => ControlFlow::CONTINUE, None => ControlFlow::CONTINUE,
@ -2059,7 +2059,7 @@ where
flag: &'a mut bool, flag: &'a mut bool,
p: &'a mut impl FnMut(&T) -> bool, p: &'a mut impl FnMut(&T) -> bool,
mut fold: impl FnMut(Acc, T) -> R + 'a, mut fold: impl FnMut(Acc, T) -> R + 'a,
) -> impl FnMut(Acc, T) -> ControlFlow<Acc, R> + 'a { ) -> impl FnMut(Acc, T) -> ControlFlow<R, Acc> + 'a {
move |acc, x| { move |acc, x| {
if p(&x) { if p(&x) {
ControlFlow::from_try(fold(acc, x)) ControlFlow::from_try(fold(acc, x))
@ -2372,7 +2372,7 @@ where
fn check<T, Acc, R: Try<Ok = Acc>>( fn check<T, Acc, R: Try<Ok = Acc>>(
mut n: usize, mut n: usize,
mut fold: impl FnMut(Acc, T) -> R, mut fold: impl FnMut(Acc, T) -> R,
) -> impl FnMut(Acc, T) -> ControlFlow<Acc, R> { ) -> impl FnMut(Acc, T) -> ControlFlow<R, Acc> {
move |acc, x| { move |acc, x| {
n -= 1; n -= 1;
let r = fold(acc, x); let r = fold(acc, x);
@ -2496,7 +2496,7 @@ where
fn check<'a, T, Acc, R: Try<Ok = Acc>>( fn check<'a, T, Acc, R: Try<Ok = Acc>>(
n: &'a mut usize, n: &'a mut usize,
mut fold: impl FnMut(Acc, T) -> R + 'a, mut fold: impl FnMut(Acc, T) -> R + 'a,
) -> impl FnMut(Acc, T) -> ControlFlow<Acc, R> + 'a { ) -> impl FnMut(Acc, T) -> ControlFlow<R, Acc> + 'a {
move |acc, x| { move |acc, x| {
*n -= 1; *n -= 1;
let r = fold(acc, x); let r = fold(acc, x);
@ -2681,7 +2681,7 @@ where
state: &'a mut St, state: &'a mut St,
f: &'a mut impl FnMut(&mut St, T) -> Option<B>, f: &'a mut impl FnMut(&mut St, T) -> Option<B>,
mut fold: impl FnMut(Acc, B) -> R + 'a, mut fold: impl FnMut(Acc, B) -> R + 'a,
) -> impl FnMut(Acc, T) -> ControlFlow<Acc, R> + 'a { ) -> impl FnMut(Acc, T) -> ControlFlow<R, Acc> + 'a {
move |acc, x| match f(state, x) { move |acc, x| match f(state, x) {
None => ControlFlow::Break(try { acc }), None => ControlFlow::Break(try { acc }),
Some(x) => ControlFlow::from_try(fold(acc, x)), Some(x) => ControlFlow::from_try(fold(acc, x)),

4
library/core/src/iter/traits/double_ended.rs
View file

@ -339,9 +339,7 @@ pub trait DoubleEndedIterator: Iterator {
P: FnMut(&Self::Item) -> bool, P: FnMut(&Self::Item) -> bool,
{ {
#[inline] #[inline]
fn check<T>( fn check<T>(mut predicate: impl FnMut(&T) -> bool) -> impl FnMut((), T) -> ControlFlow<T> {
mut predicate: impl FnMut(&T) -> bool,
) -> impl FnMut((), T) -> ControlFlow<(), T> {
move |(), x| { move |(), x| {
if predicate(&x) { ControlFlow::Break(x) } else { ControlFlow::CONTINUE } if predicate(&x) { ControlFlow::Break(x) } else { ControlFlow::CONTINUE }
} }

14
library/core/src/iter/traits/iterator.rs
View file

@ -2109,7 +2109,7 @@ pub trait Iterator {
F: FnMut(Self::Item) -> bool, F: FnMut(Self::Item) -> bool,
{ {
#[inline] #[inline]
fn check<T>(mut f: impl FnMut(T) -> bool) -> impl FnMut((), T) -> ControlFlow<(), ()> { fn check<T>(mut f: impl FnMut(T) -> bool) -> impl FnMut((), T) -> ControlFlow<()> {
move |(), x| { move |(), x| {
if f(x) { ControlFlow::CONTINUE } else { ControlFlow::BREAK } if f(x) { ControlFlow::CONTINUE } else { ControlFlow::BREAK }
} }
@ -2162,7 +2162,7 @@ pub trait Iterator {
F: FnMut(Self::Item) -> bool, F: FnMut(Self::Item) -> bool,
{ {
#[inline] #[inline]
fn check<T>(mut f: impl FnMut(T) -> bool) -> impl FnMut((), T) -> ControlFlow<(), ()> { fn check<T>(mut f: impl FnMut(T) -> bool) -> impl FnMut((), T) -> ControlFlow<()> {
move |(), x| { move |(), x| {
if f(x) { ControlFlow::BREAK } else { ControlFlow::CONTINUE } if f(x) { ControlFlow::BREAK } else { ControlFlow::CONTINUE }
} }
@ -2222,9 +2222,7 @@ pub trait Iterator {
P: FnMut(&Self::Item) -> bool, P: FnMut(&Self::Item) -> bool,
{ {
#[inline] #[inline]
fn check<T>( fn check<T>(mut predicate: impl FnMut(&T) -> bool) -> impl FnMut((), T) -> ControlFlow<T> {
mut predicate: impl FnMut(&T) -> bool,
) -> impl FnMut((), T) -> ControlFlow<(), T> {
move |(), x| { move |(), x| {
if predicate(&x) { ControlFlow::Break(x) } else { ControlFlow::CONTINUE } if predicate(&x) { ControlFlow::Break(x) } else { ControlFlow::CONTINUE }
} }
@ -2255,9 +2253,7 @@ pub trait Iterator {
F: FnMut(Self::Item) -> Option<B>, F: FnMut(Self::Item) -> Option<B>,
{ {
#[inline] #[inline]
fn check<T, B>( fn check<T, B>(mut f: impl FnMut(T) -> Option<B>) -> impl FnMut((), T) -> ControlFlow<B> {
mut f: impl FnMut(T) -> Option<B>,
) -> impl FnMut((), T) -> ControlFlow<(), B> {
move |(), x| match f(x) { move |(), x| match f(x) {
Some(x) => ControlFlow::Break(x), Some(x) => ControlFlow::Break(x),
None => ControlFlow::CONTINUE, None => ControlFlow::CONTINUE,
@ -2296,7 +2292,7 @@ pub trait Iterator {
R: Try<Ok = bool>, R: Try<Ok = bool>,
{ {
#[inline] #[inline]
fn check<F, T, R>(mut f: F) -> impl FnMut((), T) -> ControlFlow<(), Result<T, R::Error>> fn check<F, T, R>(mut f: F) -> impl FnMut((), T) -> ControlFlow<Result<T, R::Error>>
where where
F: FnMut(&T) -> R, F: FnMut(&T) -> R,
R: Try<Ok = bool>, R: Try<Ok = bool>,

12
library/core/src/ops/control_flow.rs
View file

@ -3,7 +3,7 @@ use crate::ops::Try;
/// Used to make try_fold closures more like normal loops /// Used to make try_fold closures more like normal loops
#[unstable(feature = "control_flow_enum", reason = "new API", issue = "75744")] #[unstable(feature = "control_flow_enum", reason = "new API", issue = "75744")]
#[derive(Debug, Clone, Copy, PartialEq)] #[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 in the loop, using the given value for the next iteration
Continue(C), Continue(C),
/// Exit the loop, yielding the given value /// 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")] #[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 Ok = C;
type Error = B; type Error = B;
#[inline] #[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. /// Returns `true` if this is a `Break` variant.
#[inline] #[inline]
#[unstable(feature = "control_flow_enum", reason = "new API", issue = "75744")] #[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`. /// Create a `ControlFlow` from any type implementing `Try`.
#[unstable(feature = "control_flow_enum", reason = "new API", issue = "75744")] #[unstable(feature = "control_flow_enum", reason = "new API", issue = "75744")]
#[inline] #[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`, /// 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. /// 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(()); 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`, /// APIs like `try_for_each` don't need values with `Break`,
/// so this provides a way to avoid typing `(())`, if you prefer it. /// so this provides a way to avoid typing `(())`, if you prefer it.
/// ///