summaryrefslogtreecommitdiffstats
path: root/third_party/rust/futures-0.1.31/src/future/and_then.rs
diff options
context:
space:
mode:
Diffstat (limited to 'third_party/rust/futures-0.1.31/src/future/and_then.rs')
-rw-r--r--third_party/rust/futures-0.1.31/src/future/and_then.rs38
1 files changed, 38 insertions, 0 deletions
diff --git a/third_party/rust/futures-0.1.31/src/future/and_then.rs b/third_party/rust/futures-0.1.31/src/future/and_then.rs
new file mode 100644
index 0000000000..2e5b6aa16e
--- /dev/null
+++ b/third_party/rust/futures-0.1.31/src/future/and_then.rs
@@ -0,0 +1,38 @@
+use {Future, IntoFuture, Poll};
+use super::chain::Chain;
+
+/// Future for the `and_then` combinator, chaining a computation onto the end of
+/// another future which completes successfully.
+///
+/// This is created by the `Future::and_then` method.
+#[derive(Debug)]
+#[must_use = "futures do nothing unless polled"]
+pub struct AndThen<A, B, F> where A: Future, B: IntoFuture {
+ state: Chain<A, B::Future, F>,
+}
+
+pub fn new<A, B, F>(future: A, f: F) -> AndThen<A, B, F>
+ where A: Future,
+ B: IntoFuture,
+{
+ AndThen {
+ state: Chain::new(future, f),
+ }
+}
+
+impl<A, B, F> Future for AndThen<A, B, F>
+ where A: Future,
+ B: IntoFuture<Error=A::Error>,
+ F: FnOnce(A::Item) -> B,
+{
+ type Item = B::Item;
+ type Error = B::Error;
+
+ fn poll(&mut self) -> Poll<B::Item, B::Error> {
+ self.state.poll(|result, f| {
+ result.map(|e| {
+ Err(f(e).into_future())
+ })
+ })
+ }
+}