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#![allow(dead_code)]
//! Definition of the `PollFn` adapter combinator
use std::fmt;
use std::future::Future;
use std::pin::Pin;
use std::task::{Context, Poll};
/// Future for the [`poll_fn`] function.
pub struct PollFn<F> {
f: F,
}
impl<F> Unpin for PollFn<F> {}
/// Creates a new future wrapping around a function returning [`Poll`].
pub fn poll_fn<T, F>(f: F) -> PollFn<F>
where
F: FnMut(&mut Context<'_>) -> Poll<T>,
{
PollFn { f }
}
impl<F> fmt::Debug for PollFn<F> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("PollFn").finish()
}
}
impl<T, F> Future for PollFn<F>
where
F: FnMut(&mut Context<'_>) -> Poll<T>,
{
type Output = T;
fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<T> {
(&mut self.f)(cx)
}
}
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