combine/
future_ext.rs

1use crate::lib::future::Future;
2use crate::lib::marker::Unpin;
3use crate::lib::pin::Pin;
4use crate::lib::task::{Context, Poll};
5
6// Replace usage of this with std::future::poll_fn once it stabilizes
7pub struct PollFn<F> {
8    f: F,
9}
10
11impl<F> Unpin for PollFn<F> {}
12
13pub fn poll_fn<T, F>(f: F) -> PollFn<F>
14where
15    F: FnMut(&mut Context<'_>) -> Poll<T>,
16{
17    PollFn { f }
18}
19
20impl<T, F> Future for PollFn<F>
21where
22    F: FnMut(&mut Context<'_>) -> Poll<T>,
23{
24    type Output = T;
25
26    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<T> {
27        (&mut self.f)(cx)
28    }
29}