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Diffstat (limited to '')
-rw-r--r-- | library/core/src/iter/sources/repeat_with.rs | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/library/core/src/iter/sources/repeat_with.rs b/library/core/src/iter/sources/repeat_with.rs index 6f62662d8..ab2d0472b 100644 --- a/library/core/src/iter/sources/repeat_with.rs +++ b/library/core/src/iter/sources/repeat_with.rs @@ -1,4 +1,5 @@ use crate::iter::{FusedIterator, TrustedLen}; +use crate::ops::Try; /// Creates a new iterator that repeats elements of type `A` endlessly by /// applying the provided closure, the repeater, `F: FnMut() -> A`. @@ -89,6 +90,22 @@ impl<A, F: FnMut() -> A> Iterator for RepeatWith<F> { fn size_hint(&self) -> (usize, Option<usize>) { (usize::MAX, None) } + + #[inline] + fn try_fold<Acc, Fold, R>(&mut self, mut init: Acc, mut fold: Fold) -> R + where + Fold: FnMut(Acc, Self::Item) -> R, + R: Try<Output = Acc>, + { + // This override isn't strictly needed, but avoids the need to optimize + // away the `next`-always-returns-`Some` and emphasizes that the `?` + // is the only way to exit the loop. + + loop { + let item = (self.repeater)(); + init = fold(init, item)?; + } + } } #[stable(feature = "iterator_repeat_with", since = "1.28.0")] |