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Diffstat (limited to 'tokio/src/future/pending.rs')
-rw-r--r-- | tokio/src/future/pending.rs | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/tokio/src/future/pending.rs b/tokio/src/future/pending.rs new file mode 100644 index 00000000..c844ebc3 --- /dev/null +++ b/tokio/src/future/pending.rs @@ -0,0 +1,44 @@ +use std::future::Future; +use std::marker; +use sdt::pin::Pin; +use std::task::{Context, Poll}; + +/// Future for the [`pending()`] function. +#[derive(Debug)] +#[must_use = "futures do nothing unless you `.await` or poll them"] +struct Pending<T> { + _data: marker::PhantomData<T>, +} + +/// Creates a future which never resolves, representing a computation that never +/// finishes. +/// +/// The returned future will forever return [`Poll::Pending`]. +/// +/// # Examples +/// +/// ```no_run +/// use tokio::future; +/// +/// #[tokio::main] +/// async fn main { +/// future::pending().await; +/// unreachable!(); +/// } +/// ``` +pub async fn pending() -> ! { + Pending { + _data: marker::PhantomData, + }.await +} + +impl<T> Future for Pending<T> { + type Output = !; + + fn poll(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<T> { + Poll::Pending + } +} + +impl<T> Unpin for Pending<T> { +} |