1 files changed, 39 insertions, 0 deletions
diff --git a/third_party/rust/futures-0.1.29/src/future/select2.rs b/third_party/rust/futures-0.1.29/src/future/select2.rs
new file mode 100644
index 0000000000..073f67be4a
--- /dev/null
+++ b/third_party/rust/futures-0.1.29/src/future/select2.rs
@@ -0,0 +1,39 @@
+use {Future, Poll, Async};
+use future::Either;
+
+/// Future for the `select2` combinator, waiting for one of two differently-typed
+/// futures to complete.
+///
+/// This is created by the [`Future::select2`] method.
+///
+/// [`Future::select2`]: trait.Future.html#method.select2
+#[must_use = "futures do nothing unless polled"]
+#[derive(Debug)]
+pub struct Select2<A, B> {
+    inner: Option<(A, B)>,
+}
+
+pub fn new<A, B>(a: A, b: B) -> Select2<A, B> {
+    Select2 { inner: Some((a, b)) }
+}
+
+impl<A, B> Future for Select2<A, B> where A: Future, B: Future {
+    type Item = Either<(A::Item, B), (B::Item, A)>;
+    type Error = Either<(A::Error, B), (B::Error, A)>;
+
+    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
+        let (mut a, mut b) = self.inner.take().expect("cannot poll Select2 twice");
+        match a.poll() {
+            Err(e) => Err(Either::A((e, b))),
+            Ok(Async::Ready(x)) => Ok(Async::Ready(Either::A((x, b)))),
+            Ok(Async::NotReady) => match b.poll() {
+                Err(e) => Err(Either::B((e, a))),
+                Ok(Async::Ready(x)) => Ok(Async::Ready(Either::B((x, a)))),
+                Ok(Async::NotReady) => {
+                    self.inner = Some((a, b));
+                    Ok(Async::NotReady)
+                }
+            }
+        }
+    }
+}