1use core::fmt;
2use core::pin::Pin;
3use futures_core::future::{Future, TryFuture};
4use futures_core::ready;
5use futures_core::stream::TryStream;
6use futures_core::task::{Context, Poll};
7use pin_project_lite::pin_project;
8
9pin_project! {
10 /// Future for the [`try_for_each`](super::TryStreamExt::try_for_each) method.
11 #[must_use = "futures do nothing unless you `.await` or poll them"]
12 pub struct TryForEach<St, Fut, F> {
13 #[pin]
14 stream: St,
15 f: F,
16 #[pin]
17 future: Option<Fut>,
18 }
19}
20
21impl<St, Fut, F> fmt::Debug for TryForEach<St, Fut, F>
22where
23 St: fmt::Debug,
24 Fut: fmt::Debug,
25{
26 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
27 f.debug_struct("TryForEach")
28 .field("stream", &self.stream)
29 .field("future", &self.future)
30 .finish()
31 }
32}
33
34impl<St, Fut, F> TryForEach<St, Fut, F>
35where
36 St: TryStream,
37 F: FnMut(St::Ok) -> Fut,
38 Fut: TryFuture<Ok = (), Error = St::Error>,
39{
40 pub(super) fn new(stream: St, f: F) -> Self {
41 Self { stream, f, future: None }
42 }
43}
44
45impl<St, Fut, F> Future for TryForEach<St, Fut, F>
46where
47 St: TryStream,
48 F: FnMut(St::Ok) -> Fut,
49 Fut: TryFuture<Ok = (), Error = St::Error>,
50{
51 type Output = Result<(), St::Error>;
52
53 fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
54 let mut this = self.project();
55 loop {
56 if let Some(fut) = this.future.as_mut().as_pin_mut() {
57 ready!(fut.try_poll(cx))?;
58 this.future.set(None);
59 } else {
60 match ready!(this.stream.as_mut().try_poll_next(cx)?) {
61 Some(e) => this.future.set(Some((this.f)(e))),
62 None => break,
63 }
64 }
65 }
66 Poll::Ready(Ok(()))
67 }
68}
69