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-rw-r--r--third_party/rust/itertools/src/repeatn.rs59
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
+{}