blob: 4ea9b4a78b400b8bea3171f0ea69d1db1c03e27d [file] [log] [blame]
use core::marker::{Unpin, PhantomData};
use core::pin::Pin;
use futures_core::stream::Stream;
use futures_core::task::{LocalWaker, Poll};
/// A stream which contains no elements.
///
/// This stream can be created with the `stream::empty` function.
#[derive(Debug)]
#[must_use = "streams do nothing unless polled"]
pub struct Empty<T> {
_phantom: PhantomData<T>
}
/// Creates a stream which contains no elements.
///
/// The returned stream will always return `Ready(None)` when polled.
pub fn empty<T>() -> Empty<T> {
Empty {
_phantom: PhantomData
}
}
impl<T> Unpin for Empty<T> {}
impl<T> Stream for Empty<T> {
type Item = T;
fn poll_next(self: Pin<&mut Self>, _: &LocalWaker) -> Poll<Option<Self::Item>> {
Poll::Ready(None)
}
}