Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 48 insertions, 0 deletions

diff --git a/third_party/rust/futures-0.1.31/src/future/chain.rs b/third_party/rust/futures-0.1.31/src/future/chain.rs
new file mode 100644
index 0000000000..1bf5cd639c
--- /dev/null
+++ b/third_party/rust/futures-0.1.31/src/future/chain.rs
@@ -0,0 +1,48 @@
+use core::mem;
+
+use {Future, Poll, Async};
+
+#[derive(Debug)]
+pub enum Chain<A, B, C> where A: Future {
+    First(A, C),
+    Second(B),
+    Done,
+}
+
+impl<A, B, C> Chain<A, B, C>
+    where A: Future,
+          B: Future,
+{
+    pub fn new(a: A, c: C) -> Chain<A, B, C> {
+        Chain::First(a, c)
+    }
+
+    pub fn poll<F>(&mut self, f: F) -> Poll<B::Item, B::Error>
+        where F: FnOnce(Result<A::Item, A::Error>, C)
+                        -> Result<Result<B::Item, B>, B::Error>,
+    {
+        let a_result = match *self {
+            Chain::First(ref mut a, _) => {
+                match a.poll() {
+                    Ok(Async::NotReady) => return Ok(Async::NotReady),
+                    Ok(Async::Ready(t)) => Ok(t),
+                    Err(e) => Err(e),
+                }
+            }
+            Chain::Second(ref mut b) => return b.poll(),
+            Chain::Done => panic!("cannot poll a chained future twice"),
+        };
+        let data = match mem::replace(self, Chain::Done) {
+            Chain::First(_, c) => c,
+            _ => panic!(),
+        };
+        match f(a_result, data)? {
+            Ok(e) => Ok(Async::Ready(e)),
+            Err(mut b) => {
+                let ret = b.poll();
+                *self = Chain::Second(b);
+                ret
+            }
+        }
+    }
+}