messagebus 0.15.2

MessageBus allows intercommunicate with messages between modules
Documentation 
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use std::{marker::PhantomData, pin::Pin};

use futures::{Stream, StreamExt};

pub trait AsyncIterator: Send {
    type Item: Send;

    fn next(self: Pin<&mut Self>) -> impl futures::Future<Output = Option<Self::Item>> + Send + '_;

    fn size_hint(&self) -> (usize, Option<usize>) {
        (0, None)
    }

    fn map<U: Send, C: Send + FnMut(Self::Item) -> U>(self, cb: C) -> impl AsyncIterator<Item = U>
    where
        Self: Sized,
    {
        Map { inner: self, cb }
    }
}

pin_project_lite::pin_project! {
    pub struct Map<U, I: AsyncIterator, F: FnMut(I::Item) ->U> {
        #[pin]
        inner: I,
        cb: F,
    }
}

impl<U: Send, I: AsyncIterator, F: Send + FnMut(I::Item) -> U> AsyncIterator for Map<U, I, F> {
    type Item = U;

    async fn next(self: Pin<&mut Self>) -> Option<U> {
        let this = self.project();
        Some((this.cb)(this.inner.next().await?))
    }
}

pub struct Iter<I: Iterator> {
    inner: I,
}

impl<I: Send + Iterator + Unpin> AsyncIterator for Iter<I>
where
    I::Item: Send,
{
    type Item = I::Item;

    #[inline]
    async fn next(self: Pin<&mut Self>) -> Option<Self::Item> {
        self.get_mut().inner.next()
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        self.inner.size_hint()
    }
}

pub fn iter<I: IntoIterator + Send>(inner: I) -> Iter<I::IntoIter>
where
    I::IntoIter: Send + Unpin,
    I::Item: Send,
{
    Iter {
        inner: inner.into_iter(),
    }
}
pin_project_lite::pin_project! {
    pub struct StreamIter<S: Stream> {
        #[pin]
        inner: S,
    }
}

impl<S: Send + Stream> AsyncIterator for StreamIter<S>
where
    S::Item: Send,
{
    type Item = S::Item;

    #[inline]
    async fn next(self: Pin<&mut Self>) -> Option<Self::Item> {
        self.project().inner.next().await
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        self.inner.size_hint()
    }
}

pub fn stream<S: Send + Stream>(inner: S) -> StreamIter<S>
where
    S::Item: Send,
{
    StreamIter { inner }
}

pub struct Once<I>(Option<I>);
impl<I: Send + Unpin> AsyncIterator for Once<I> {
    type Item = I;

    async fn next(self: Pin<&mut Self>) -> Option<Self::Item> {
        self.get_mut().0.take()
    }
}

pub fn once<I: Send + Unpin>(item: I) -> Once<I> {
    Once(Some(item))
}

pub struct Empty<I>(PhantomData<I>);
impl<I: Send> AsyncIterator for Empty<I> {
    type Item = I;

    async fn next(self: Pin<&mut Self>) -> Option<Self::Item> {
        None
    }
}

pub fn empty<I: Send + Unpin>() -> Empty<I> {
    Empty(Default::default())
}

impl<I: Send> AsyncIterator for tokio::sync::mpsc::Receiver<I> {
    type Item = I;

    async fn next(self: Pin<&mut Self>) -> Option<Self::Item> {
        self.get_mut().recv().await
    }
}

impl<I: Send> AsyncIterator for tokio::sync::oneshot::Receiver<I> {
    type Item = I;

    async fn next(self: Pin<&mut Self>) -> Option<Self::Item> {
        match self.await {
            Ok(item) => Some(item),
            Err(_) => None,
        }
    }
}