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use super::assert_stream;
use core::marker;
use core::pin::Pin;
use futures_core::stream::{FusedStream, Stream};
use futures_core::task::{Context, Poll};
/// Stream for the [`pending()`] function.
#[derive(Debug)]
#[must_use = "streams do nothing unless polled"]
pub struct Pending<T> {
_data: marker::PhantomData<T>,
}
/// Creates a stream which never returns any elements.
///
/// The returned stream will always return `Pending` when polled.
pub fn pending<T>() -> Pending<T> {
assert_stream::<T, _>(Pending { _data: marker::PhantomData })
}
impl<T> Unpin for Pending<T> {}
impl<T> FusedStream for Pending<T> {
fn is_terminated(&self) -> bool {
true
}
}
impl<T> Stream for Pending<T> {
type Item = T;
fn poll_next(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Option<Self::Item>> {
Poll::Pending
}
fn size_hint(&self) -> (usize, Option<usize>) {
(0, Some(0))
}
}
impl<T> Clone for Pending<T> {
fn clone(&self) -> Self {
pending()
}
}