45 lines
1.1 KiB
Rust
45 lines
1.1 KiB
Rust
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use crate::Stream;
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use core::future::Future;
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use core::marker::PhantomPinned;
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use core::pin::Pin;
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use core::task::{Context, Poll};
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use pin_project_lite::pin_project;
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pin_project! {
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/// Future for the [`next`](super::StreamExt::next) method.
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///
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/// # Cancel safety
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///
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/// This method is cancel safe. It only
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/// holds onto a reference to the underlying stream,
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/// so dropping it will never lose a value.
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///
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#[derive(Debug)]
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#[must_use = "futures do nothing unless you `.await` or poll them"]
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pub struct Next<'a, St: ?Sized> {
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stream: &'a mut St,
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// Make this future `!Unpin` for compatibility with async trait methods.
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#[pin]
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_pin: PhantomPinned,
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}
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}
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impl<'a, St: ?Sized> Next<'a, St> {
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pub(super) fn new(stream: &'a mut St) -> Self {
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Next {
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stream,
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_pin: PhantomPinned,
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}
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}
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}
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impl<St: ?Sized + Stream + Unpin> Future for Next<'_, St> {
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type Output = Option<St::Item>;
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fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
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let me = self.project();
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Pin::new(me.stream).poll_next(cx)
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}
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}
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