blob: e2c796bb7aa86c9eabb5396f4a513dcae1c40971 [file] [log] [blame]
use core::marker;
use core::mem::PinMut;
use futures_core::future::Future;
use futures_core::task::{self, Poll};
/// A future which is never resolved.
///
/// This future can be created with the [`empty()`] function.
#[derive(Debug)]
#[must_use = "futures do nothing unless polled"]
pub struct Empty<T> {
_data: marker::PhantomData<T>,
}
/// Creates a future which never resolves, representing a computation that never
/// finishes.
///
/// The returned future will forever return [`Poll::Pending`].
///
/// # Examples
///
/// ```ignore
/// #![feature(async_await, await_macro, futures_api)]
/// # futures::executor::block_on(async {
/// use futures::future;
///
/// let future = future::empty();
/// let () = await!(future);
/// unreachable!();
/// # });
/// ```
pub fn empty<T>() -> Empty<T> {
Empty { _data: marker::PhantomData }
}
impl<T> Future for Empty<T> {
type Output = T;
fn poll(self: PinMut<Self>, _: &mut task::Context) -> Poll<T> {
Poll::Pending
}
}