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use super::assert_stream;
use core::pin::Pin;
use futures_core::stream::{FusedStream, Stream};
use futures_core::task::{Context, Poll};
/// Stream for the [`repeat`] function.
#[derive(Debug, Clone)]
#[must_use = "streams do nothing unless polled"]
pub struct Repeat<T> {
item: T,
}
/// Create a stream which produces the same item repeatedly.
///
/// The stream never terminates. Note that you likely want to avoid
/// usage of `collect` or such on the returned stream as it will exhaust
/// available memory as it tries to just fill up all RAM.
///
/// ```
/// # futures::executor::block_on(async {
/// use futures::stream::{self, StreamExt};
///
/// let stream = stream::repeat(9);
/// assert_eq!(vec![9, 9, 9], stream.take(3).collect::<Vec<i32>>().await);
/// # });
/// ```
pub fn repeat<T>(item: T) -> Repeat<T>
where
T: Clone,
{
assert_stream::<T, _>(Repeat { item })
}
impl<T> Unpin for Repeat<T> {}
impl<T> Stream for Repeat<T>
where
T: Clone,
{
type Item = T;
fn poll_next(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Option<Self::Item>> {
Poll::Ready(Some(self.item.clone()))
}
fn size_hint(&self) -> (usize, Option<usize>) {
(usize::max_value(), None)
}
}
impl<T> FusedStream for Repeat<T>
where
T: Clone,
{
fn is_terminated(&self) -> bool {
false
}
}