diff --git a/src/libcore/iter.rs b/src/libcore/iter.rs index e2a4fdfe79bf1..39b319e6ac867 100644 --- a/src/libcore/iter.rs +++ b/src/libcore/iter.rs @@ -2155,7 +2155,7 @@ type IterateState<'a, T> = (|T|: 'a -> T, Option, bool); /// from a given seed value. pub type Iterate<'a, T> = Unfold<'a, T, IterateState<'a, T>>; -/// Creates a new iterator that produces an infinite sequence of +/// Create a new iterator that produces an infinite sequence of /// repeated applications of the given function `f`. pub fn iterate<'a, T: Clone>(seed: T, f: |T|: 'a -> T) -> Iterate<'a, T> { Unfold::new((f, Some(seed), true), |st| { @@ -2174,6 +2174,11 @@ pub fn iterate<'a, T: Clone>(seed: T, f: |T|: 'a -> T) -> Iterate<'a, T> { }) } +/// Create a new iterator that endlessly repeats the element `elt`. +pub fn repeat(elt: T) -> Repeat { + Repeat::new(elt) +} + /// Functions for lexicographical ordering of sequences. /// /// Lexicographical ordering through `<`, `<=`, `>=`, `>` requires diff --git a/src/libcore/prelude.rs b/src/libcore/prelude.rs index 680f91945d103..543a1560747b9 100644 --- a/src/libcore/prelude.rs +++ b/src/libcore/prelude.rs @@ -41,7 +41,7 @@ pub use option::{Option, Some, None}; pub use result::{Result, Ok, Err}; // Reexported functions -pub use iter::range; +pub use iter::{range, repeat}; pub use mem::drop; // Reexported types and traits diff --git a/src/libcoretest/iter.rs b/src/libcoretest/iter.rs index 98db377b0d576..5d333d48e96d4 100644 --- a/src/libcoretest/iter.rs +++ b/src/libcoretest/iter.rs @@ -846,6 +846,14 @@ fn test_iterate() { assert_eq!(it.next(), Some(8u)); } +#[test] +fn test_repeat() { + let mut it = repeat(42u); + assert_eq!(it.next(), Some(42u)); + assert_eq!(it.next(), Some(42u)); + assert_eq!(it.next(), Some(42u)); +} + #[bench] fn bench_rposition(b: &mut Bencher) { let it: Vec = range(0u, 300).collect(); diff --git a/src/libstd/prelude.rs b/src/libstd/prelude.rs index db9f3114cda14..f9217e89cdd71 100644 --- a/src/libstd/prelude.rs +++ b/src/libstd/prelude.rs @@ -53,7 +53,7 @@ // Reexported functions #[doc(no_inline)] pub use from_str::from_str; -#[doc(no_inline)] pub use iter::range; +#[doc(no_inline)] pub use iter::{range, repeat}; #[doc(no_inline)] pub use mem::drop; // Reexported types and traits