Adding upstream version 86.0.1.upstream/86.0.1upstream

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

1 files changed, 45 insertions, 0 deletions

diff --git a/third_party/rust/futures-0.1.29/src/future/poll_fn.rs b/third_party/rust/futures-0.1.29/src/future/poll_fn.rs
new file mode 100644
index 0000000000..d96bf2f98d
--- /dev/null
+++ b/third_party/rust/futures-0.1.29/src/future/poll_fn.rs
@@ -0,0 +1,45 @@
+//! Definition of the `PollFn` adapter combinator
+
+use {Future, Poll};
+
+/// A future which adapts a function returning `Poll`.
+///
+/// Created by the `poll_fn` function.
+#[derive(Debug)]
+#[must_use = "futures do nothing unless polled"]
+pub struct PollFn<F> {
+    inner: F,
+}
+
+/// Creates a new future wrapping around a function returning `Poll`.
+///
+/// Polling the returned future delegates to the wrapped function.
+///
+/// # Examples
+///
+/// ```
+/// use futures::future::poll_fn;
+/// use futures::{Async, Poll};
+///
+/// fn read_line() -> Poll<String, std::io::Error> {
+///     Ok(Async::Ready("Hello, World!".into()))
+/// }
+///
+/// let read_future = poll_fn(read_line);
+/// ```
+pub fn poll_fn<T, E, F>(f: F) -> PollFn<F>
+    where F: FnMut() -> ::Poll<T, E>
+{
+    PollFn { inner: f }
+}
+
+impl<T, E, F> Future for PollFn<F>
+    where F: FnMut() -> Poll<T, E>
+{
+    type Item = T;
+    type Error = E;
+
+    fn poll(&mut self) -> Poll<T, E> {
+        (self.inner)()
+    }
+}