forked from mirror/async-std
57 lines
1.2 KiB
Rust
57 lines
1.2 KiB
Rust
use std::future::Future;
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use std::pin::Pin;
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use async_macros::MaybeDone;
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use pin_project_lite::pin_project;
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use crate::task::{Context, Poll};
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pin_project! {
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#[allow(missing_docs)]
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#[allow(missing_debug_implementations)]
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pub struct Race<L, R>
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where
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L: Future,
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R: Future<Output = L::Output>
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{
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#[pin] left: MaybeDone<L>,
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#[pin] right: MaybeDone<R>,
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}
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}
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impl<L, R> Race<L, R>
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where
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L: Future,
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R: Future<Output = L::Output>,
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{
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pub(crate) fn new(left: L, right: R) -> Self {
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Self {
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left: MaybeDone::new(left),
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right: MaybeDone::new(right),
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}
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}
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}
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impl<L, R> Future for Race<L, R>
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where
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L: Future,
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R: Future<Output = L::Output>,
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{
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type Output = L::Output;
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fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
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let this = self.project();
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let mut left = this.left;
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if Future::poll(Pin::new(&mut left), cx).is_ready() {
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return Poll::Ready(left.take().unwrap());
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}
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let mut right = this.right;
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if Future::poll(Pin::new(&mut right), cx).is_ready() {
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return Poll::Ready(right.take().unwrap());
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}
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Poll::Pending
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}
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}
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