futures_util/sink/
feed.rs

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1use core::pin::Pin;
2use futures_core::future::Future;
3use futures_core::ready;
4use futures_core::task::{Context, Poll};
5use futures_sink::Sink;
6
7/// Future for the [`feed`](super::SinkExt::feed) method.
8#[derive(Debug)]
9#[must_use = "futures do nothing unless you `.await` or poll them"]
10pub struct Feed<'a, Si: ?Sized, Item> {
11    sink: &'a mut Si,
12    item: Option<Item>,
13}
14
15// Pinning is never projected to children
16impl<Si: Unpin + ?Sized, Item> Unpin for Feed<'_, Si, Item> {}
17
18impl<'a, Si: Sink<Item> + Unpin + ?Sized, Item> Feed<'a, Si, Item> {
19    pub(super) fn new(sink: &'a mut Si, item: Item) -> Self {
20        Feed { sink, item: Some(item) }
21    }
22
23    pub(super) fn sink_pin_mut(&mut self) -> Pin<&mut Si> {
24        Pin::new(self.sink)
25    }
26
27    pub(super) fn is_item_pending(&self) -> bool {
28        self.item.is_some()
29    }
30}
31
32impl<Si: Sink<Item> + Unpin + ?Sized, Item> Future for Feed<'_, Si, Item> {
33    type Output = Result<(), Si::Error>;
34
35    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
36        let this = self.get_mut();
37        let mut sink = Pin::new(&mut this.sink);
38        ready!(sink.as_mut().poll_ready(cx))?;
39        let item = this.item.take().expect("polled Feed after completion");
40        sink.as_mut().start_send(item)?;
41        Poll::Ready(Ok(()))
42    }
43}
futures_util/sink/feed.rs

futures_util/sink/
feed.rs
