futures_util/stream/stream/
any.rs

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1use core::fmt;
2use core::pin::Pin;
3use futures_core::future::{FusedFuture, Future};
4use futures_core::ready;
5use futures_core::stream::Stream;
6use futures_core::task::{Context, Poll};
7use pin_project_lite::pin_project;
8
9pin_project! {
10    /// Future for the [`any`](super::StreamExt::any) method.
11    #[must_use = "futures do nothing unless you `.await` or poll them"]
12    pub struct Any<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 Any<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.debug_struct("Any")
29            .field("stream", &self.stream)
30            .field("done", &self.done)
31            .field("future", &self.future)
32            .finish()
33    }
34}
35
36impl<St, Fut, F> Any<St, Fut, F>
37where
38    St: Stream,
39    F: FnMut(St::Item) -> 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 Any<St, Fut, F>
48where
49    St: Stream,
50    F: FnMut(St::Item) -> 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 Any<St, Fut, F>
59where
60    St: Stream,
61    F: FnMut(St::Item) -> Fut,
62    Fut: Future<Output = bool>,
63{
64    type Output = bool;
65
66    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<bool> {
67        let mut this = self.project();
68        Poll::Ready(loop {
69            if let Some(fut) = this.future.as_mut().as_pin_mut() {
70                // we're currently processing a future to produce a new value
71                let res = ready!(fut.poll(cx));
72                this.future.set(None);
73                if res {
74                    *this.done = true;
75                    break true;
76                } // early exit
77            } else if !*this.done {
78                // we're waiting on a new item from the stream
79                match ready!(this.stream.as_mut().poll_next(cx)) {
80                    Some(item) => {
81                        this.future.set(Some((this.f)(item)));
82                    }
83                    None => {
84                        *this.done = true;
85                        break false;
86                    }
87                }
88            } else {
89                panic!("Any polled after completion")
90            }
91        })
92    }
93}
futures_util/stream/stream/any.rs

futures_util/stream/stream/
any.rs
