futures_util/stream/stream/
unzip.rs

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1use core::mem;
2use core::pin::Pin;
3use futures_core::future::{FusedFuture, Future};
4use futures_core::ready;
5use futures_core::stream::{FusedStream, Stream};
6use futures_core::task::{Context, Poll};
7use pin_project_lite::pin_project;
8
9pin_project! {
10    /// Future for the [`unzip`](super::StreamExt::unzip) method.
11    #[derive(Debug)]
12    #[must_use = "futures do nothing unless you `.await` or poll them"]
13    pub struct Unzip<St, FromA, FromB> {
14        #[pin]
15        stream: St,
16        left: FromA,
17        right: FromB,
18    }
19}
20
21impl<St: Stream, FromA: Default, FromB: Default> Unzip<St, FromA, FromB> {
22    fn finish(self: Pin<&mut Self>) -> (FromA, FromB) {
23        let this = self.project();
24        (mem::take(this.left), mem::take(this.right))
25    }
26
27    pub(super) fn new(stream: St) -> Self {
28        Self { stream, left: Default::default(), right: Default::default() }
29    }
30}
31
32impl<St, A, B, FromA, FromB> FusedFuture for Unzip<St, FromA, FromB>
33where
34    St: FusedStream<Item = (A, B)>,
35    FromA: Default + Extend<A>,
36    FromB: Default + Extend<B>,
37{
38    fn is_terminated(&self) -> bool {
39        self.stream.is_terminated()
40    }
41}
42
43impl<St, A, B, FromA, FromB> Future for Unzip<St, FromA, FromB>
44where
45    St: Stream<Item = (A, B)>,
46    FromA: Default + Extend<A>,
47    FromB: Default + Extend<B>,
48{
49    type Output = (FromA, FromB);
50
51    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<(FromA, FromB)> {
52        let mut this = self.as_mut().project();
53        loop {
54            match ready!(this.stream.as_mut().poll_next(cx)) {
55                Some(e) => {
56                    this.left.extend(Some(e.0));
57                    this.right.extend(Some(e.1));
58                }
59                None => return Poll::Ready(self.finish()),
60            }
61        }
62    }
63}
futures_util/stream/stream/unzip.rs

futures_util/stream/stream/
unzip.rs
