| use core::fmt; |
| use core::marker::PhantomData; |
| use core::pin::Pin; |
| use futures_core::future::Future; |
| use futures_core::ready; |
| use futures_core::stream::Stream; |
| use futures_core::task::{Context, Poll}; |
| use futures_sink::Sink; |
| use pin_project_lite::pin_project; |
| |
| pin_project! { |
| /// Sink for the [`with`](super::SinkExt::with) method. |
| #[must_use = "sinks do nothing unless polled"] |
| pub struct With<Si, Item, U, Fut, F> { |
| #[pin] |
| sink: Si, |
| f: F, |
| #[pin] |
| state: Option<Fut>, |
| _phantom: PhantomData<fn(U) -> Item>, |
| } |
| } |
| |
| impl<Si, Item, U, Fut, F> fmt::Debug for With<Si, Item, U, Fut, F> |
| where |
| Si: fmt::Debug, |
| Fut: fmt::Debug, |
| { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| f.debug_struct("With").field("sink", &self.sink).field("state", &self.state).finish() |
| } |
| } |
| |
| impl<Si, Item, U, Fut, F> With<Si, Item, U, Fut, F> |
| where |
| Si: Sink<Item>, |
| F: FnMut(U) -> Fut, |
| Fut: Future, |
| { |
| pub(super) fn new<E>(sink: Si, f: F) -> Self |
| where |
| Fut: Future<Output = Result<Item, E>>, |
| E: From<Si::Error>, |
| { |
| Self { state: None, sink, f, _phantom: PhantomData } |
| } |
| } |
| |
| impl<Si, Item, U, Fut, F> Clone for With<Si, Item, U, Fut, F> |
| where |
| Si: Clone, |
| F: Clone, |
| Fut: Clone, |
| { |
| fn clone(&self) -> Self { |
| Self { |
| state: self.state.clone(), |
| sink: self.sink.clone(), |
| f: self.f.clone(), |
| _phantom: PhantomData, |
| } |
| } |
| } |
| |
| // Forwarding impl of Stream from the underlying sink |
| impl<S, Item, U, Fut, F> Stream for With<S, Item, U, Fut, F> |
| where |
| S: Stream + Sink<Item>, |
| F: FnMut(U) -> Fut, |
| Fut: Future, |
| { |
| type Item = S::Item; |
| |
| delegate_stream!(sink); |
| } |
| |
| impl<Si, Item, U, Fut, F, E> With<Si, Item, U, Fut, F> |
| where |
| Si: Sink<Item>, |
| F: FnMut(U) -> Fut, |
| Fut: Future<Output = Result<Item, E>>, |
| E: From<Si::Error>, |
| { |
| delegate_access_inner!(sink, Si, ()); |
| |
| /// Completes the processing of previous item if any. |
| fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), E>> { |
| let mut this = self.project(); |
| |
| let item = match this.state.as_mut().as_pin_mut() { |
| None => return Poll::Ready(Ok(())), |
| Some(fut) => ready!(fut.poll(cx))?, |
| }; |
| this.state.set(None); |
| this.sink.start_send(item)?; |
| Poll::Ready(Ok(())) |
| } |
| } |
| |
| impl<Si, Item, U, Fut, F, E> Sink<U> for With<Si, Item, U, Fut, F> |
| where |
| Si: Sink<Item>, |
| F: FnMut(U) -> Fut, |
| Fut: Future<Output = Result<Item, E>>, |
| E: From<Si::Error>, |
| { |
| type Error = E; |
| |
| fn poll_ready(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> { |
| ready!(self.as_mut().poll(cx))?; |
| ready!(self.project().sink.poll_ready(cx)?); |
| Poll::Ready(Ok(())) |
| } |
| |
| fn start_send(self: Pin<&mut Self>, item: U) -> Result<(), Self::Error> { |
| let mut this = self.project(); |
| |
| assert!(this.state.is_none()); |
| this.state.set(Some((this.f)(item))); |
| Ok(()) |
| } |
| |
| fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> { |
| ready!(self.as_mut().poll(cx))?; |
| ready!(self.project().sink.poll_flush(cx)?); |
| Poll::Ready(Ok(())) |
| } |
| |
| fn poll_close(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> { |
| ready!(self.as_mut().poll(cx))?; |
| ready!(self.project().sink.poll_close(cx)?); |
| Poll::Ready(Ok(())) |
| } |
| } |