xtra 0.6.0

A tiny actor framework
Documentation 
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use std::future::Future;
use std::pin::Pin;
use std::task::{Context, Poll};

use futures_util::FutureExt;

use crate::address::{ActorJoinHandle, Address};
use crate::chan::RefCounter;

/// Scope a given task to the lifecycle of an actor - see [`ScopedTask`].
pub fn scoped<A, Rc, F, R>(address: &Address<A, Rc>, task: F) -> ScopedTask<F>
where
    Rc: RefCounter,
    F: Future<Output = R>,
{
    ScopedTask {
        join_handle: address.join(),
        fut: task,
    }
}

pin_project_lite::pin_project! {
    /// A task that is scoped to the lifecycle of an actor. This means that when the associated
    /// actor stops, the task will stop too. This future will either complete when the inner future
    /// completes, or when the actor is dropped, whichever comes first. If the inner future completes
    /// successfully, `Some(result)` will be returned, else `None` will be returned if the actor
    /// is stopped before it could be polled to completion.
    #[must_use = "Futures do nothing unless polled"]
    pub struct ScopedTask<F: ?Sized> {
        join_handle: ActorJoinHandle,
        #[pin]
        fut: F,
    }
}

impl<F> Future for ScopedTask<F>
where
    F: Future,
{
    type Output = Option<F::Output>;

    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        let this = self.project();

        match this.join_handle.poll_unpin(cx) {
            Poll::Ready(()) => Poll::Ready(None),
            Poll::Pending => match this.fut.poll(cx) {
                Poll::Ready(v) => Poll::Ready(Some(v)),
                Poll::Pending => Poll::Pending,
            },
        }
    }
}