1 files changed, 43 insertions, 0 deletions
diff --git a/third_party/rust/futures-util/src/sink/feed.rs b/third_party/rust/futures-util/src/sink/feed.rs
new file mode 100644
index 0000000000..6701f7a1b4
--- /dev/null
+++ b/third_party/rust/futures-util/src/sink/feed.rs
@@ -0,0 +1,43 @@
+use core::pin::Pin;
+use futures_core::future::Future;
+use futures_core::ready;
+use futures_core::task::{Context, Poll};
+use futures_sink::Sink;
+
+/// Future for the [`feed`](super::SinkExt::feed) method.
+#[derive(Debug)]
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct Feed<'a, Si: ?Sized, Item> {
+    sink: &'a mut Si,
+    item: Option<Item>,
+}
+
+// Pinning is never projected to children
+impl<Si: Unpin + ?Sized, Item> Unpin for Feed<'_, Si, Item> {}
+
+impl<'a, Si: Sink<Item> + Unpin + ?Sized, Item> Feed<'a, Si, Item> {
+    pub(super) fn new(sink: &'a mut Si, item: Item) -> Self {
+        Feed { sink, item: Some(item) }
+    }
+
+    pub(super) fn sink_pin_mut(&mut self) -> Pin<&mut Si> {
+        Pin::new(self.sink)
+    }
+
+    pub(super) fn is_item_pending(&self) -> bool {
+        self.item.is_some()
+    }
+}
+
+impl<Si: Sink<Item> + Unpin + ?Sized, Item> Future for Feed<'_, Si, Item> {
+    type Output = Result<(), Si::Error>;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        let this = self.get_mut();
+        let mut sink = Pin::new(&mut this.sink);
+        ready!(sink.as_mut().poll_ready(cx))?;
+        let item = this.item.take().expect("polled Feed after completion");
+        sink.as_mut().start_send(item)?;
+        Poll::Ready(Ok(()))
+    }
+}