1use crate::future::maybe_done::{maybe_done, MaybeDone};
2
3use pin_project_lite::pin_project;
4use std::future::Future;
5use std::pin::Pin;
6use std::task::{Context, Poll};
7
8pub(crate) fn try_join3<T1, F1, T2, F2, T3, F3, E>(
9 future1: F1,
10 future2: F2,
11 future3: F3,
12) -> TryJoin3<F1, F2, F3>
13where
14 F1: Future<Output = Result<T1, E>>,
15 F2: Future<Output = Result<T2, E>>,
16 F3: Future<Output = Result<T3, E>>,
17{
18 TryJoin3 {
19 future1: maybe_done(future:future1),
20 future2: maybe_done(future:future2),
21 future3: maybe_done(future:future3),
22 }
23}
24
25pin_project! {
26 pub(crate) struct TryJoin3<F1, F2, F3>
27 where
28 F1: Future,
29 F2: Future,
30 F3: Future,
31 {
32 #[pin]
33 future1: MaybeDone<F1>,
34 #[pin]
35 future2: MaybeDone<F2>,
36 #[pin]
37 future3: MaybeDone<F3>,
38 }
39}
40
41impl<T1, F1, T2, F2, T3, F3, E> Future for TryJoin3<F1, F2, F3>
42where
43 F1: Future<Output = Result<T1, E>>,
44 F2: Future<Output = Result<T2, E>>,
45 F3: Future<Output = Result<T3, E>>,
46{
47 type Output = Result<(T1, T2, T3), E>;
48
49 fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
50 let mut all_done = true;
51
52 let mut me = self.project();
53
54 if me.future1.as_mut().poll(cx).is_pending() {
55 all_done = false;
56 } else if me.future1.as_mut().output_mut().unwrap().is_err() {
57 return Poll::Ready(Err(me.future1.take_output().unwrap().err().unwrap()));
58 }
59
60 if me.future2.as_mut().poll(cx).is_pending() {
61 all_done = false;
62 } else if me.future2.as_mut().output_mut().unwrap().is_err() {
63 return Poll::Ready(Err(me.future2.take_output().unwrap().err().unwrap()));
64 }
65
66 if me.future3.as_mut().poll(cx).is_pending() {
67 all_done = false;
68 } else if me.future3.as_mut().output_mut().unwrap().is_err() {
69 return Poll::Ready(Err(me.future3.take_output().unwrap().err().unwrap()));
70 }
71
72 if all_done {
73 Poll::Ready(Ok((
74 me.future1.take_output().unwrap().ok().unwrap(),
75 me.future2.take_output().unwrap().ok().unwrap(),
76 me.future3.take_output().unwrap().ok().unwrap(),
77 )))
78 } else {
79 Poll::Pending
80 }
81 }
82}
83