| use core::fmt; |
| use core::pin::Pin; |
| use futures_core::future::{FusedFuture, Future}; |
| use futures_core::stream::{FusedStream, Stream}; |
| use futures_core::task::{Context, Poll}; |
| use pin_project::pin_project; |
| |
| /// Future for the [`for_each`](super::StreamExt::for_each) method. |
| #[pin_project] |
| #[must_use = "futures do nothing unless you `.await` or poll them"] |
| pub struct ForEach<St, Fut, F> { |
| #[pin] |
| stream: St, |
| f: F, |
| #[pin] |
| future: Option<Fut>, |
| } |
| |
| impl<St, Fut, F> fmt::Debug for ForEach<St, Fut, F> |
| where |
| St: fmt::Debug, |
| Fut: fmt::Debug, |
| { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| f.debug_struct("ForEach") |
| .field("stream", &self.stream) |
| .field("future", &self.future) |
| .finish() |
| } |
| } |
| |
| impl<St, Fut, F> ForEach<St, Fut, F> |
| where St: Stream, |
| F: FnMut(St::Item) -> Fut, |
| Fut: Future<Output = ()>, |
| { |
| pub(super) fn new(stream: St, f: F) -> ForEach<St, Fut, F> { |
| ForEach { |
| stream, |
| f, |
| future: None, |
| } |
| } |
| } |
| |
| impl<St, Fut, F> FusedFuture for ForEach<St, Fut, F> |
| where St: FusedStream, |
| F: FnMut(St::Item) -> Fut, |
| Fut: Future<Output = ()>, |
| { |
| fn is_terminated(&self) -> bool { |
| self.future.is_none() && self.stream.is_terminated() |
| } |
| } |
| |
| impl<St, Fut, F> Future for ForEach<St, Fut, F> |
| where St: Stream, |
| F: FnMut(St::Item) -> Fut, |
| Fut: Future<Output = ()>, |
| { |
| type Output = (); |
| |
| fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> { |
| let mut this = self.project(); |
| loop { |
| if let Some(fut) = this.future.as_mut().as_pin_mut() { |
| ready!(fut.poll(cx)); |
| this.future.set(None); |
| } else if let Some(item) = ready!(this.stream.as_mut().poll_next(cx)) { |
| this.future.set(Some((this.f)(item))); |
| } else { |
| break; |
| } |
| } |
| Poll::Ready(()) |
| } |
| } |