| use core::fmt; |
| use core::pin::Pin; |
| use futures_core::future::{FusedFuture, Future}; |
| use futures_core::ready; |
| use futures_core::stream::{FusedStream, Stream}; |
| use futures_core::task::{Context, Poll}; |
| use pin_project_lite::pin_project; |
| |
| pin_project! { |
| /// Future for the [`count`](super::StreamExt::count) method. |
| #[must_use = "futures do nothing unless you `.await` or poll them"] |
| pub struct Count<St> { |
| #[pin] |
| stream: St, |
| count: usize |
| } |
| } |
| |
| impl<St> fmt::Debug for Count<St> |
| where |
| St: fmt::Debug, |
| { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| f.debug_struct("Count").field("stream", &self.stream).field("count", &self.count).finish() |
| } |
| } |
| |
| impl<St: Stream> Count<St> { |
| pub(super) fn new(stream: St) -> Self { |
| Self { stream, count: 0 } |
| } |
| } |
| |
| impl<St: FusedStream> FusedFuture for Count<St> { |
| fn is_terminated(&self) -> bool { |
| self.stream.is_terminated() |
| } |
| } |
| |
| impl<St: Stream> Future for Count<St> { |
| type Output = usize; |
| |
| fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> { |
| let mut this = self.project(); |
| |
| Poll::Ready(loop { |
| match ready!(this.stream.as_mut().poll_next(cx)) { |
| Some(_) => *this.count += 1, |
| None => break *this.count, |
| } |
| }) |
| } |
| } |