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use crate::stream::{Fuse, StreamExt, TryStreamExt};
use core::fmt;
use core::pin::Pin;
use futures_core::future::Future;
use futures_core::ready;
use futures_core::stream::{Stream, TryStream};
use futures_core::task::{Context, Poll};
use futures_sink::Sink;
/// Future for the [`send_all`](super::SinkExt::send_all) method.
#[must_use = "futures do nothing unless you `.await` or poll them"]
pub struct SendAll<'a, Si, St>
where
Si: ?Sized,
St: ?Sized + TryStream,
{
sink: &'a mut Si,
stream: Fuse<&'a mut St>,
buffered: Option<St::Ok>,
}
impl<Si, St> fmt::Debug for SendAll<'_, Si, St>
where
Si: fmt::Debug + ?Sized,
St: fmt::Debug + ?Sized + TryStream,
St::Ok: fmt::Debug,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("SendAll")
.field("sink", &self.sink)
.field("stream", &self.stream)
.field("buffered", &self.buffered)
.finish()
}
}
// Pinning is never projected to any fields
impl<Si, St> Unpin for SendAll<'_, Si, St>
where
Si: Unpin + ?Sized,
St: TryStream + Unpin + ?Sized,
{
}
impl<'a, Si, St, Ok, Error> SendAll<'a, Si, St>
where
Si: Sink<Ok, Error = Error> + Unpin + ?Sized,
St: TryStream<Ok = Ok, Error = Error> + Stream + Unpin + ?Sized,
{
pub(super) fn new(sink: &'a mut Si, stream: &'a mut St) -> Self {
Self { sink, stream: stream.fuse(), buffered: None }
}
fn try_start_send(
&mut self,
cx: &mut Context<'_>,
item: St::Ok,
) -> Poll<Result<(), Si::Error>> {
debug_assert!(self.buffered.is_none());
match Pin::new(&mut self.sink).poll_ready(cx)? {
Poll::Ready(()) => Poll::Ready(Pin::new(&mut self.sink).start_send(item)),
Poll::Pending => {
self.buffered = Some(item);
Poll::Pending
}
}
}
}
impl<Si, St, Ok, Error> Future for SendAll<'_, Si, St>
where
Si: Sink<Ok, Error = Error> + Unpin + ?Sized,
St: Stream<Item = Result<Ok, Error>> + Unpin + ?Sized,
{
type Output = Result<(), Error>;
fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
let this = &mut *self;
// If we've got an item buffered already, we need to write it to the
// sink before we can do anything else
if let Some(item) = this.buffered.take() {
ready!(this.try_start_send(cx, item))?
}
loop {
match this.stream.try_poll_next_unpin(cx)? {
Poll::Ready(Some(item)) => ready!(this.try_start_send(cx, item))?,
Poll::Ready(None) => {
ready!(Pin::new(&mut this.sink).poll_flush(cx))?;
return Poll::Ready(Ok(()));
}
Poll::Pending => {
ready!(Pin::new(&mut this.sink).poll_flush(cx))?;
return Poll::Pending;
}
}
}
}
}