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use core::fmt;
use core::pin::Pin;
use futures_core::future::{Future, TryFuture};
use futures_core::stream::TryStream;
use futures_core::task::{Context, Poll};
use pin_utils::{unsafe_pinned, unsafe_unpinned};
#[must_use = "futures do nothing unless you `.await` or poll them"]
pub struct TryForEach<St, Fut, F> {
stream: St,
f: F,
future: Option<Fut>,
}
impl<St: Unpin, Fut: Unpin, F> Unpin for TryForEach<St, Fut, F> {}
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>,
{
unsafe_pinned!(stream: St);
unsafe_unpinned!(f: F);
unsafe_pinned!(future: Option<Fut>);
pub(super) fn new(stream: St, f: F) -> TryForEach<St, Fut, F> {
TryForEach {
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(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
loop {
if let Some(future) = self.as_mut().future().as_pin_mut() {
ready!(future.try_poll(cx))?;
}
self.as_mut().future().set(None);
match ready!(self.as_mut().stream().try_poll_next(cx)?) {
Some(e) => {
let future = (self.as_mut().f())(e);
self.as_mut().future().set(Some(future));
}
None => return Poll::Ready(Ok(())),
}
}
}
}