1use core::fmt;
2use core::pin::Pin;
3use futures_core::future::{FusedFuture, Future};
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_all`](super::TryStreamExt::try_all) method.
11 #[must_use = "futures do nothing unless you `.await` or poll them"]
12 pub struct TryAll<St, Fut, F> {
13 #[pin]
14 stream: St,
15 f: F,
16 done: bool,
17 #[pin]
18 future: Option<Fut>,
19 }
20}
21
22impl<St, Fut, F> fmt::Debug for TryAll<St, Fut, F>
23where
24 St: fmt::Debug,
25 Fut: fmt::Debug,
26{
27 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
28 f&mut DebugStruct<'_, '_>.debug_struct("TryAll")
29 .field("stream", &self.stream)
30 .field("done", &self.done)
31 .field(name:"future", &self.future)
32 .finish()
33 }
34}
35
36impl<St, Fut, F> TryAll<St, Fut, F>
37where
38 St: TryStream,
39 F: FnMut(St::Ok) -> Fut,
40 Fut: Future<Output = bool>,
41{
42 pub(super) fn new(stream: St, f: F) -> Self {
43 Self { stream, f, done: false, future: None }
44 }
45}
46
47impl<St, Fut, F> FusedFuture for TryAll<St, Fut, F>
48where
49 St: TryStream,
50 F: FnMut(St::Ok) -> Fut,
51 Fut: Future<Output = bool>,
52{
53 fn is_terminated(&self) -> bool {
54 self.done && self.future.is_none()
55 }
56}
57
58impl<St, Fut, F> Future for TryAll<St, Fut, F>
59where
60 St: TryStream,
61 F: FnMut(St::Ok) -> Fut,
62 Fut: Future<Output = bool>,
63{
64 type Output = Result<bool, St::Error>;
65
66 fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<bool, St::Error>> {
67 let mut this = self.project();
68
69 Poll::Ready(loop {
70 if let Some(fut) = this.future.as_mut().as_pin_mut() {
71 // we're currently processing a future to produce a new value
72 let acc = ready!(fut.poll(cx));
73 this.future.set(None);
74 if !acc {
75 *this.done = true;
76 break Ok(false);
77 } // early exit
78 } else if !*this.done {
79 // we're waiting on a new item from the stream
80 match ready!(this.stream.as_mut().try_poll_next(cx)) {
81 Some(Ok(item)) => {
82 this.future.set(Some((this.f)(item)));
83 }
84 Some(Err(err)) => {
85 *this.done = true;
86 break Err(err);
87 }
88 None => {
89 *this.done = true;
90 break Ok(true);
91 }
92 }
93 } else {
94 panic!("TryAll polled after completion")
95 }
96 })
97 }
98}
99