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use core::fmt;
use core::pin::Pin;
use futures_core::future::{Future, TryFuture};
use futures_core::ready;
use futures_core::stream::TryStream;
use futures_core::task::{Context, Poll};
use pin_project_lite::pin_project;
pin_project! {
/// Future for the [`try_for_each`](super::TryStreamExt::try_for_each) method.
#[must_use = "futures do nothing unless you `.await` or poll them"]
pub struct TryForEach<St, Fut, F> {
#[pin]
stream: St,
f: F,
#[pin]
future: Option<Fut>,
}
}
impl<St, Fut, F> fmt::Debug for TryForEach<St, Fut, F>
where
St: fmt::Debug,
Fut: fmt::Debug,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("TryForEach")
.field("stream", &self.stream)
.field("future", &self.future)
.finish()
}
}
impl<St, Fut, F> TryForEach<St, Fut, F>
where
St: TryStream,
F: FnMut(St::Ok) -> Fut,
Fut: TryFuture<Ok = (), Error = St::Error>,
{
pub(super) fn new(stream: St, f: F) -> Self {
Self { stream, f, future: None }
}
}
impl<St, Fut, F> Future for TryForEach<St, Fut, F>
where
St: TryStream,
F: FnMut(St::Ok) -> Fut,
Fut: TryFuture<Ok = (), Error = St::Error>,
{
type Output = Result<(), St::Error>;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
let mut this = self.project();
loop {
if let Some(fut) = this.future.as_mut().as_pin_mut() {
ready!(fut.try_poll(cx))?;
this.future.set(None);
} else {
match ready!(this.stream.as_mut().try_poll_next(cx)?) {
Some(e) => this.future.set(Some((this.f)(e))),
None => break,
}
}
}
Poll::Ready(Ok(()))
}
}