1 files changed, 36 insertions, 0 deletions
diff --git a/third_party/rust/futures-0.1.31/src/future/then.rs b/third_party/rust/futures-0.1.31/src/future/then.rs
new file mode 100644
index 0000000000..188fb8fa80
--- /dev/null
+++ b/third_party/rust/futures-0.1.31/src/future/then.rs
@@ -0,0 +1,36 @@
+use {Future, IntoFuture, Poll};
+use super::chain::Chain;
+
+/// Future for the `then` combinator, chaining computations on the end of
+/// another future regardless of its outcome.
+///
+/// This is created by the `Future::then` method.
+#[derive(Debug)]
+#[must_use = "futures do nothing unless polled"]
+pub struct Then<A, B, F> where A: Future, B: IntoFuture {
+    state: Chain<A, B::Future, F>,
+}
+
+pub fn new<A, B, F>(future: A, f: F) -> Then<A, B, F>
+    where A: Future,
+          B: IntoFuture,
+{
+    Then {
+        state: Chain::new(future, f),
+    }
+}
+
+impl<A, B, F> Future for Then<A, B, F>
+    where A: Future,
+          B: IntoFuture,
+          F: FnOnce(Result<A::Item, A::Error>) -> B,
+{
+    type Item = B::Item;
+    type Error = B::Error;
+
+    fn poll(&mut self) -> Poll<B::Item, B::Error> {
+        self.state.poll(|a, f| {
+            Ok(Err(f(a).into_future()))
+        })
+    }
+}