#
actix_service/
ready.rs

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    //! When MSRV is 1.48, replace with `core::future::Ready` and `core::future::ready()`.

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

    /// Future for the [`ready`](ready()) function.
    #[derive(Debug, Clone)]
    #[must_use = "futures do nothing unless you `.await` or poll them"]
    pub struct Ready<T> {
        val: Option<T>,
    }

    impl<T> Ready<T> {
        /// Unwraps the value from this immediately ready future.
        #[inline]
        pub fn into_inner(mut self) -> T {
            self.val.take().unwrap()
        }
    }

    impl<T> Unpin for Ready<T> {}

    impl<T> Future for Ready<T> {
        type Output = T;

        #[inline]
        fn poll(mut self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<T> {
            let val = self.val.take().expect("Ready can not be polled twice.");
            Poll::Ready(val)
        }
    }

    /// Creates a future that is immediately ready with a value.
    #[allow(dead_code)]
    pub(crate) fn ready<T>(val: T) -> Ready<T> {
        Ready { val: Some(val) }
    }

    /// Create a future that is immediately ready with a success value.
    #[allow(dead_code)]
    pub(crate) fn ok<T, E>(val: T) -> Ready<Result<T, E>> {
        Ready { val: Some(Ok(val)) }
    }

    /// Create a future that is immediately ready with an error value.
    #[allow(dead_code)]
    pub(crate) fn err<T, E>(err: E) -> Ready<Result<T, E>> {
        Ready {
            val: Some(Err(err)),
        }
    }