| use core::pin::Pin; |
| use futures_core::stream::{FusedStream, Stream, TryStream}; |
| use futures_core::task::{Context, Poll}; |
| #[cfg(feature = "sink")] |
| use futures_sink::Sink; |
| use pin_utils::unsafe_pinned; |
| |
| /// Stream for the [`try_flatten`](super::TryStreamExt::try_flatten) method. |
| #[derive(Debug)] |
| #[must_use = "streams do nothing unless polled"] |
| pub struct TryFlatten<St> |
| where |
| St: TryStream, |
| { |
| stream: St, |
| next: Option<St::Ok>, |
| } |
| |
| impl<St> Unpin for TryFlatten<St> |
| where |
| St: TryStream + Unpin, |
| St::Ok: Unpin, |
| { |
| } |
| |
| impl<St> TryFlatten<St> |
| where |
| St: TryStream, |
| { |
| unsafe_pinned!(stream: St); |
| unsafe_pinned!(next: Option<St::Ok>); |
| } |
| |
| impl<St> TryFlatten<St> |
| where |
| St: TryStream, |
| St::Ok: TryStream, |
| <St::Ok as TryStream>::Error: From<St::Error>, |
| { |
| pub(super) fn new(stream: St) -> Self { |
| Self { stream, next: None } |
| } |
| |
| /// 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(self: Pin<&mut Self>) -> Pin<&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> FusedStream for TryFlatten<St> |
| where |
| St: TryStream + FusedStream, |
| St::Ok: TryStream, |
| <St::Ok as TryStream>::Error: From<St::Error>, |
| { |
| fn is_terminated(&self) -> bool { |
| self.next.is_none() && self.stream.is_terminated() |
| } |
| } |
| |
| impl<St> Stream for TryFlatten<St> |
| where |
| St: TryStream, |
| St::Ok: TryStream, |
| <St::Ok as TryStream>::Error: From<St::Error>, |
| { |
| type Item = Result<<St::Ok as TryStream>::Ok, <St::Ok as TryStream>::Error>; |
| |
| fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> { |
| loop { |
| if self.next.is_none() { |
| match ready!(self.as_mut().stream().try_poll_next(cx)?) { |
| Some(e) => self.as_mut().next().set(Some(e)), |
| None => return Poll::Ready(None), |
| } |
| } |
| |
| if let Some(item) = ready!(self |
| .as_mut() |
| .next() |
| .as_pin_mut() |
| .unwrap() |
| .try_poll_next(cx)?) |
| { |
| return Poll::Ready(Some(Ok(item))); |
| } else { |
| self.as_mut().next().set(None); |
| } |
| } |
| } |
| } |
| |
| // Forwarding impl of Sink from the underlying stream |
| #[cfg(feature = "sink")] |
| impl<S, Item> Sink<Item> for TryFlatten<S> |
| where |
| S: TryStream + Sink<Item>, |
| { |
| type Error = <S as Sink<Item>>::Error; |
| |
| delegate_sink!(stream, Item); |
| } |