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use core::pin::Pin;
use futures_core::stream::{FusedStream, Stream};
use futures_core::task::{Context, Poll};
use futures_sink::Sink;
use pin_project_lite::pin_project;
pin_project! {
/// Sink for the [`sink_map_err`](super::SinkExt::sink_map_err) method.
#[derive(Debug, Clone)]
#[must_use = "sinks do nothing unless polled"]
pub struct SinkMapErr<Si, F> {
#[pin]
sink: Si,
f: Option<F>,
}
}
impl<Si, F> SinkMapErr<Si, F> {
pub(super) fn new(sink: Si, f: F) -> Self {
Self { sink, f: Some(f) }
}
delegate_access_inner!(sink, Si, ());
fn take_f(self: Pin<&mut Self>) -> F {
self.project().f.take().expect("polled MapErr after completion")
}
}
impl<Si, F, E, Item> Sink<Item> for SinkMapErr<Si, F>
where
Si: Sink<Item>,
F: FnOnce(Si::Error) -> E,
{
type Error = E;
fn poll_ready(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
self.as_mut().project().sink.poll_ready(cx).map_err(|e| self.as_mut().take_f()(e))
}
fn start_send(mut self: Pin<&mut Self>, item: Item) -> Result<(), Self::Error> {
self.as_mut().project().sink.start_send(item).map_err(|e| self.as_mut().take_f()(e))
}
fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
self.as_mut().project().sink.poll_flush(cx).map_err(|e| self.as_mut().take_f()(e))
}
fn poll_close(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
self.as_mut().project().sink.poll_close(cx).map_err(|e| self.as_mut().take_f()(e))
}
}
// Forwarding impl of Stream from the underlying sink
impl<S: Stream, F> Stream for SinkMapErr<S, F> {
type Item = S::Item;
delegate_stream!(sink);
}
impl<S: FusedStream, F> FusedStream for SinkMapErr<S, F> {
fn is_terminated(&self) -> bool {
self.sink.is_terminated()
}
}