| use crate::stream::StreamExt; |
| use core::pin::Pin; |
| use futures_core::future::{FusedFuture, Future}; |
| use futures_core::stream::Stream; |
| use futures_core::task::{Context, Poll}; |
| |
| /// Future for the [`into_future`](super::StreamExt::into_future) method. |
| #[derive(Debug)] |
| #[must_use = "futures do nothing unless you `.await` or poll them"] |
| pub struct StreamFuture<St> { |
| stream: Option<St>, |
| } |
| |
| impl<St: Stream + Unpin> StreamFuture<St> { |
| pub(super) fn new(stream: St) -> StreamFuture<St> { |
| StreamFuture { stream: Some(stream) } |
| } |
| |
| /// Acquires a reference to the underlying stream that this combinator is |
| /// pulling from. |
| /// |
| /// This method returns an `Option` to account for the fact that `StreamFuture`'s |
| /// implementation of `Future::poll` consumes the underlying stream during polling |
| /// in order to return it to the caller of `Future::poll` if the stream yielded |
| /// an element. |
| pub fn get_ref(&self) -> Option<&St> { |
| self.stream.as_ref() |
| } |
| |
| /// 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. |
| /// |
| /// This method returns an `Option` to account for the fact that `StreamFuture`'s |
| /// implementation of `Future::poll` consumes the underlying stream during polling |
| /// in order to return it to the caller of `Future::poll` if the stream yielded |
| /// an element. |
| pub fn get_mut(&mut self) -> Option<&mut St> { |
| self.stream.as_mut() |
| } |
| |
| /// 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. |
| /// |
| /// This method returns an `Option` to account for the fact that `StreamFuture`'s |
| /// implementation of `Future::poll` consumes the underlying stream during polling |
| /// in order to return it to the caller of `Future::poll` if the stream yielded |
| /// an element. |
| pub fn get_pin_mut(self: Pin<&mut Self>) -> Option<Pin<&mut St>> { |
| self.get_mut().stream.as_mut().map(Pin::new) |
| } |
| |
| /// 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. |
| /// |
| /// This method returns an `Option` to account for the fact that `StreamFuture`'s |
| /// implementation of `Future::poll` consumes the underlying stream during polling |
| /// in order to return it to the caller of `Future::poll` if the stream yielded |
| /// an element. |
| pub fn into_inner(self) -> Option<St> { |
| self.stream |
| } |
| } |
| |
| impl<St: Stream + Unpin> FusedFuture for StreamFuture<St> { |
| fn is_terminated(&self) -> bool { |
| self.stream.is_none() |
| } |
| } |
| |
| impl<St: Stream + Unpin> Future for StreamFuture<St> { |
| type Output = (Option<St::Item>, St); |
| |
| fn poll( |
| mut self: Pin<&mut Self>, |
| cx: &mut Context<'_>, |
| ) -> Poll<Self::Output> { |
| let item = { |
| let s = self.stream.as_mut().expect("polling StreamFuture twice"); |
| ready!(s.poll_next_unpin(cx)) |
| }; |
| let stream = self.stream.take().unwrap(); |
| Poll::Ready((item, stream)) |
| } |
| } |