pending.rs.html -- source
Description: Source to the Rust file `src\libcore\future\pending.rs`.
Keywords: rust, rustlang, rust-lang

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    use crate::future::Future;
    use crate::marker;
    use crate::pin::Pin;
    use crate::task::{Context, Poll};

    /// Creates a future which never resolves, representing a computation that never
    /// finishes.
    ///
    /// This `struct` is created by the [`pending`] function. See its
    /// documentation for more.
    ///
    /// [`pending`]: fn.pending.html
    #[unstable(feature = "future_readiness_fns", issue = "70921")]
    #[derive(Debug)]
    #[must_use = "futures do nothing unless you `.await` or poll them"]
    pub struct Pending<T> {
        _data: marker::PhantomData<T>,
    }

    /// Creates a future which never resolves, representing a computation that never
    /// finishes.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// #![feature(future_readiness_fns)]
    /// use core::future;
    ///
    /// # async fn run() {
    /// let future = future::pending();
    /// let () = future.await;
    /// unreachable!();
    /// # }
    /// ```
    #[unstable(feature = "future_readiness_fns", issue = "70921")]
    pub fn pending<T>() -> Pending<T> {
        Pending { _data: marker::PhantomData }
    }

    #[unstable(feature = "future_readiness_fns", issue = "70921")]
    impl<T> Future for Pending<T> {
        type Output = T;

        fn poll(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<T> {
            Poll::Pending
        }
    }

    #[unstable(feature = "future_readiness_fns", issue = "70921")]
    impl<T> Unpin for Pending<T> {}

    #[unstable(feature = "future_readiness_fns", issue = "70921")]
    impl<T> Clone for Pending<T> {
        fn clone(&self) -> Self {
            pending()
        }
    }