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Diffstat (limited to '')
-rw-r--r-- | vendor/futures-util/src/future/pending.rs | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/vendor/futures-util/src/future/pending.rs b/vendor/futures-util/src/future/pending.rs new file mode 100644 index 000000000..92c78d52b --- /dev/null +++ b/vendor/futures-util/src/future/pending.rs @@ -0,0 +1,54 @@ +use super::assert_future; +use core::marker; +use core::pin::Pin; +use futures_core::future::{FusedFuture, Future}; +use futures_core::task::{Context, Poll}; + +/// Future for the [`pending()`] function. +#[derive(Debug)] +#[must_use = "futures do nothing unless you `.await` or poll them"] +pub struct Pending<T> { + _data: marker::PhantomData<T>, +} + +impl<T> FusedFuture for Pending<T> { + fn is_terminated(&self) -> bool { + true + } +} + +/// Creates a future which never resolves, representing a computation that never +/// finishes. +/// +/// The returned future will forever return [`Poll::Pending`]. +/// +/// # Examples +/// +/// ```ignore +/// # futures::executor::block_on(async { +/// use futures::future; +/// +/// let future = future::pending(); +/// let () = future.await; +/// unreachable!(); +/// # }); +/// ``` +pub fn pending<T>() -> Pending<T> { + assert_future::<T, _>(Pending { _data: marker::PhantomData }) +} + +impl<T> Future for Pending<T> { + type Output = T; + + fn poll(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<T> { + Poll::Pending + } +} + +impl<T> Unpin for Pending<T> {} + +impl<T> Clone for Pending<T> { + fn clone(&self) -> Self { + pending() + } +} |