1 use super::Feed;
2 use core::pin::Pin;
3 use futures_core::future::Future;
4 use futures_core::ready;
5 use futures_core::task::{Context, Poll};
6 use futures_sink::Sink;
7 
8 /// Future for the [`send`](super::SinkExt::send) method.
9 #[derive(Debug)]
10 #[must_use = "futures do nothing unless you `.await` or poll them"]
11 pub struct Send<'a, Si: ?Sized, Item> {
12     feed: Feed<'a, Si, Item>,
13 }
14 
15 // Pinning is never projected to children
16 impl<Si: Unpin + ?Sized, Item> Unpin for Send<'_, Si, Item> {}
17 
18 impl<'a, Si: Sink<Item> + Unpin + ?Sized, Item> Send<'a, Si, Item> {
new(sink: &'a mut Si, item: Item) -> Self19     pub(super) fn new(sink: &'a mut Si, item: Item) -> Self {
20         Self { feed: Feed::new(sink, item) }
21     }
22 }
23 
24 impl<Si: Sink<Item> + Unpin + ?Sized, Item> Future for Send<'_, Si, Item> {
25     type Output = Result<(), Si::Error>;
26 
poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output>27     fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
28         let this = &mut *self;
29 
30         if this.feed.is_item_pending() {
31             ready!(Pin::new(&mut this.feed).poll(cx))?;
32             debug_assert!(!this.feed.is_item_pending());
33         }
34 
35         // we're done sending the item, but want to block on flushing the
36         // sink
37         ready!(this.feed.sink_pin_mut().poll_flush(cx))?;
38 
39         Poll::Ready(Ok(()))
40     }
41 }
42