blob: 20e61224559cff8e3b1ce860ac316022cf98428a [file] [log] [blame]
use core::marker::Unpin;
use core::pin::PinMut;
use futures_core::future::{Future, TryFuture};
use futures_core::task::{self, Poll};
use pin_utils::{unsafe_pinned, unsafe_unpinned};
/// Future for the [`map_ok`](super::TryFutureExt::map_ok) combinator.
#[derive(Debug)]
#[must_use = "futures do nothing unless polled"]
pub struct MapOk<Fut, F> {
future: Fut,
f: Option<F>,
}
impl<Fut, F> MapOk<Fut, F> {
unsafe_pinned!(future: Fut);
unsafe_unpinned!(f: Option<F>);
/// Creates a new MapOk.
pub(super) fn new(future: Fut, f: F) -> MapOk<Fut, F> {
MapOk { future, f: Some(f) }
}
}
impl<Fut: Unpin, F> Unpin for MapOk<Fut, F> {}
impl<Fut, F, T> Future for MapOk<Fut, F>
where Fut: TryFuture,
F: FnOnce(Fut::Ok) -> T,
{
type Output = Result<T, Fut::Error>;
fn poll(
mut self: PinMut<Self>,
cx: &mut task::Context,
) -> Poll<Self::Output> {
match self.future().try_poll(cx) {
Poll::Pending => Poll::Pending,
Poll::Ready(result) => {
let op = self.f().take()
.expect("MapOk must not be polled after it returned `Poll::Ready`");
Poll::Ready(result.map(op))
}
}
}
}