1 files changed, 35 insertions, 0 deletions
diff --git a/third_party/rust/futures-0.1.31/src/stream/once.rs b/third_party/rust/futures-0.1.31/src/stream/once.rs
new file mode 100644
index 0000000000..24fb327bd6
--- /dev/null
+++ b/third_party/rust/futures-0.1.31/src/stream/once.rs
@@ -0,0 +1,35 @@
+use {Poll, Async};
+use stream::Stream;
+
+/// A stream which emits single element and then EOF.
+///
+/// This stream will never block and is always ready.
+#[derive(Debug)]
+#[must_use = "streams do nothing unless polled"]
+pub struct Once<T, E>(Option<Result<T, E>>);
+
+/// Creates a stream of single element
+///
+/// ```rust
+/// use futures::*;
+///
+/// let mut stream = stream::once::<(), _>(Err(17));
+/// assert_eq!(Err(17), stream.poll());
+/// assert_eq!(Ok(Async::Ready(None)), stream.poll());
+/// ```
+pub fn once<T, E>(item: Result<T, E>) -> Once<T, E> {
+    Once(Some(item))
+}
+
+impl<T, E> Stream for Once<T, E> {
+    type Item = T;
+    type Error = E;
+
+    fn poll(&mut self) -> Poll<Option<T>, E> {
+        match self.0.take() {
+            Some(Ok(e)) => Ok(Async::Ready(Some(e))),
+            Some(Err(e)) => Err(e),
+            None => Ok(Async::Ready(None)),
+        }
+    }
+}