| use core::pin::Pin; |
| use futures_core::future::TryFuture; |
| use futures_core::stream::{Stream, TryStream}; |
| use futures_core::task::{Context, Poll}; |
| use futures_sink::Sink; |
| use pin_utils::{unsafe_pinned, unsafe_unpinned}; |
| |
| /// Stream for the [`or_else`](super::TryStreamExt::or_else) method. |
| #[derive(Debug)] |
| #[must_use = "streams do nothing unless polled"] |
| pub struct OrElse<St, Fut, F> { |
| stream: St, |
| future: Option<Fut>, |
| f: F, |
| } |
| |
| impl<St: Unpin, Fut: Unpin, F> Unpin for OrElse<St, Fut, F> {} |
| |
| impl<St, Fut, F> OrElse<St, Fut, F> |
| where St: TryStream, |
| F: FnMut(St::Error) -> Fut, |
| Fut: TryFuture<Ok = St::Ok>, |
| { |
| unsafe_pinned!(stream: St); |
| unsafe_pinned!(future: Option<Fut>); |
| unsafe_unpinned!(f: F); |
| |
| pub(super) fn new(stream: St, f: F) -> Self { |
| Self { stream, future: None, f } |
| } |
| |
| /// Acquires a reference to the underlying stream that this combinator is |
| /// pulling from. |
| pub fn get_ref(&self) -> &St { |
| &self.stream |
| } |
| |
| /// Acquires a mutable reference to the underlying stream that this |
| /// combinator is pulling from. |
| /// |
| /// Note that care must be taken to avoid tampering with the state of the |
| /// stream which may otherwise confuse this combinator. |
| pub fn get_mut(&mut self) -> &mut St { |
| &mut self.stream |
| } |
| |
| /// Acquires a pinned mutable reference to the underlying stream that this |
| /// combinator is pulling from. |
| /// |
| /// Note that care must be taken to avoid tampering with the state of the |
| /// stream which may otherwise confuse this combinator. |
| pub fn get_pin_mut<'a>(self: Pin<&'a mut Self>) -> Pin<&'a mut St> { |
| self.stream() |
| } |
| |
| /// Consumes this combinator, returning the underlying stream. |
| /// |
| /// Note that this may discard intermediate state of this combinator, so |
| /// care should be taken to avoid losing resources when this is called. |
| pub fn into_inner(self) -> St { |
| self.stream |
| } |
| } |
| |
| impl<St, Fut, F> Stream for OrElse<St, Fut, F> |
| where St: TryStream, |
| F: FnMut(St::Error) -> Fut, |
| Fut: TryFuture<Ok = St::Ok>, |
| { |
| type Item = Result<St::Ok, Fut::Error>; |
| |
| fn poll_next( |
| mut self: Pin<&mut Self>, |
| cx: &mut Context<'_>, |
| ) -> Poll<Option<Self::Item>> { |
| if self.future.is_none() { |
| let item = match ready!(self.as_mut().stream().try_poll_next(cx)) { |
| None => return Poll::Ready(None), |
| Some(Ok(e)) => return Poll::Ready(Some(Ok(e))), |
| Some(Err(e)) => e, |
| }; |
| let fut = (self.as_mut().f())(item); |
| self.as_mut().future().set(Some(fut)); |
| } |
| |
| assert!(self.future.is_some()); |
| match ready!(self.as_mut().future().as_pin_mut().unwrap().try_poll(cx)) { |
| Ok(e) => { |
| self.as_mut().future().set(None); |
| Poll::Ready(Some(Ok(e))) |
| } |
| Err(e) => { |
| self.as_mut().future().set(None); |
| Poll::Ready(Some(Err(e))) |
| } |
| } |
| } |
| } |
| |
| // Forwarding impl of Sink from the underlying stream |
| impl<S, Fut, F, Item> Sink<Item> for OrElse<S, Fut, F> |
| where S: TryStream + Sink<Item>, |
| F: FnMut(S::Error) -> Fut, |
| Fut: TryFuture<Ok = S::Ok>, |
| { |
| type SinkError = S::SinkError; |
| |
| delegate_sink!(stream, Item); |
| } |