1 files changed, 59 insertions, 0 deletions
diff --git a/third_party/rust/itertools/src/repeatn.rs b/third_party/rust/itertools/src/repeatn.rs
new file mode 100644
index 0000000000..e025f6f6a5
--- /dev/null
+++ b/third_party/rust/itertools/src/repeatn.rs
@@ -0,0 +1,59 @@
+use std::iter::FusedIterator;
+
+/// An iterator that produces *n* repetitions of an element.
+///
+/// See [`repeat_n()`](crate::repeat_n) for more information.
+#[must_use = "iterators are lazy and do nothing unless consumed"]
+#[derive(Clone, Debug)]
+pub struct RepeatN<A> {
+    elt: Option<A>,
+    n: usize,
+}
+
+/// Create an iterator that produces `n` repetitions of `element`.
+pub fn repeat_n<A>(element: A, n: usize) -> RepeatN<A>
+    where A: Clone,
+{
+    if n == 0 {
+        RepeatN { elt: None, n, }
+    } else {
+        RepeatN { elt: Some(element), n, }
+    }
+}
+
+impl<A> Iterator for RepeatN<A>
+    where A: Clone
+{
+    type Item = A;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.n > 1 {
+            self.n -= 1;
+            self.elt.as_ref().cloned()
+        } else {
+            self.n = 0;
+            self.elt.take()
+        }
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (self.n, Some(self.n))
+    }
+}
+
+impl<A> DoubleEndedIterator for RepeatN<A>
+    where A: Clone
+{
+    #[inline]
+    fn next_back(&mut self) -> Option<Self::Item> {
+        self.next()
+    }
+}
+
+impl<A> ExactSizeIterator for RepeatN<A>
+    where A: Clone
+{}
+
+impl<A> FusedIterator for RepeatN<A>
+    where A: Clone
+{}