futures_util/stream/stream/
count.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::{FusedStream, Stream};
6use futures_core::task::{Context, Poll};
7use pin_project_lite::pin_project;
8
9pin_project! {
10    /// Future for the [`count`](super::StreamExt::count) method.
11    #[must_use = "futures do nothing unless you `.await` or poll them"]
12    pub struct Count<St> {
13        #[pin]
14        stream: St,
15        count: usize
16    }
17}
18
19impl<St> fmt::Debug for Count<St>
20where
21    St: fmt::Debug,
22{
23    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
24        f.debug_struct("Count").field("stream", &self.stream).field("count", &self.count).finish()
25    }
26}
27
28impl<St: Stream> Count<St> {
29    pub(super) fn new(stream: St) -> Self {
30        Self { stream, count: 0 }
31    }
32}
33
34impl<St: FusedStream> FusedFuture for Count<St> {
35    fn is_terminated(&self) -> bool {
36        self.stream.is_terminated()
37    }
38}
39
40impl<St: Stream> Future for Count<St> {
41    type Output = usize;
42
43    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
44        let mut this = self.project();
45
46        Poll::Ready(loop {
47            match ready!(this.stream.as_mut().poll_next(cx)) {
48                Some(_) => *this.count += 1,
49                None => break *this.count,
50            }
51        })
52    }
53}
futures_util/stream/stream/count.rs

futures_util/stream/stream/
count.rs
