Add fn repeat and Repeat

Author: cuviper

src/lib.rs

@@ -52,6 +52,7 @@ pub use sources::{empty, Empty};
 pub use sources::{from_fn, FromFn};
 pub use sources::{once, Once};
 pub use sources::{once_with, OnceWith};
+pub use sources::{repeat, Repeat};
 
 /// An interface for dealing with streaming iterators.
 pub trait StreamingIterator {

src/sources.rs

@@ -1,5 +1,6 @@
 use super::{DoubleEndedStreamingIterator, StreamingIterator};
 use core::marker::PhantomData;
+use core::usize;
 
 /// Turns a normal, non-streaming iterator into a streaming iterator.
 ///
@@ -66,6 +67,12 @@ pub fn once_with<T, F: FnOnce() -> T>(gen: F) -> OnceWith<T, F> {
     }
 }
 
+/// Creates an iterator that returns an item endlessly.
+#[inline]
+pub fn repeat<T>(item: T) -> Repeat<T> {
+    Repeat { item }
+}
+
 /// A streaming iterator which yields elements from a normal, non-streaming, iterator.
 #[derive(Clone, Debug)]
 pub struct Convert<I>
@@ -320,3 +327,31 @@ impl<T, F: FnOnce() -> T> DoubleEndedStreamingIterator for OnceWith<T, F> {
         self.advance();
     }
 }
+
+/// A simple iterator that repeats an item endlessly.
+#[derive(Clone, Debug)]
+pub struct Repeat<T> {
+    item: T,
+}
+
+impl<T> StreamingIterator for Repeat<T> {
+    type Item = T;
+
+    #[inline]
+    fn advance(&mut self) {}
+
+    #[inline]
+    fn get(&self) -> Option<&Self::Item> {
+        Some(&self.item)
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (usize::MAX, None)
+    }
+}
+
+impl<T> DoubleEndedStreamingIterator for Repeat<T> {
+    #[inline]
+    fn advance_back(&mut self) {}
+}