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use super::Join as JoinTrait;
use crate::utils::MaybeDone;
use core::fmt;
use core::future::{Future, IntoFuture};
use core::pin::Pin;
use core::task::{Context, Poll};
use pin_project::pin_project;
macro_rules! generate {
($(
(<$($Fut:ident),*>),
)*) => ($( #[allow(non_snake_case)] const _: () = {
#[pin_project]
#[must_use = "futures do nothing unless you `.await` or poll them"]
#[allow(non_snake_case)]
pub struct Join<$($Fut: Future),*> {
$(#[pin] $Fut: MaybeDone<$Fut>,)*
}
impl<$($Fut),*> fmt::Debug for Join<$($Fut),*>
where
$(
$Fut: Future + fmt::Debug,
$Fut::Output: fmt::Debug,
)*
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct(stringify!(Join))
$(.field(stringify!($Fut), &self.$Fut))*
.finish()
}
}
impl<$($Fut),*> JoinTrait for ($($Fut),*)
where
$(
$Fut: IntoFuture,
)*
{
type Output = ($($Fut::Output),*);
type Future = Join<$($Fut::IntoFuture),*>;
fn join(self) -> Self::Future {
let ($($Fut),*): ($($Fut),*) = self;
Join {
$($Fut: MaybeDone::new($Fut.into_future())),*
}
}
}
impl<$($Fut: Future),*> Future for Join<$($Fut),*> {
type Output = ($($Fut::Output),*);
fn poll(
self: Pin<&mut Self>, cx: &mut Context<'_>
) -> Poll<Self::Output> {
let mut all_done = true;
let mut futures = self.project();
$(
all_done &= futures.$Fut.as_mut().poll(cx).is_ready();
)*
if all_done {
Poll::Ready(($(futures.$Fut.take().unwrap()), *))
} else {
Poll::Pending
}
}
}
}; )*)
}
generate! {
(<A, B>),
(<A, B, C>),
(<A, B, C, D>),
(<A, B, C, D, E>),
(<A, B, C, D, E, F>),
(<A, B, C, D, E, F, G>),
(<A, B, C, D, E, F, G, H>),
(<A, B, C, D, E, F, G, H, I>),
(<A, B, C, D, E, F, G, H, I, J>),
(<A, B, C, D, E, F, G, H, I, J, K>),
(<A, B, C, D, E, F, G, H, I, J, K, L>),
}