| use core::marker::Unpin; |
| use core::pin::Pin; |
| use futures_core::stream::Stream; |
| use futures_core::task::{LocalWaker, Poll}; |
| |
| /// Stream that produces the same element repeatedly. |
| /// |
| /// This structure is created by the `stream::repeat` function. |
| #[derive(Debug)] |
| #[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. |
| /// |
| /// ``` |
| /// use futures::executor::block_on; |
| /// use futures::stream::{self, StreamExt}; |
| /// |
| /// let mut stream = stream::repeat(9); |
| /// assert_eq!(vec![9, 9, 9], block_on(stream.take(3).collect::<Vec<i32>>())); |
| /// ``` |
| pub fn repeat<T>(item: T) -> Repeat<T> |
| where T: Clone |
| { |
| 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>, _: &LocalWaker) -> Poll<Option<Self::Item>> { |
| Poll::Ready(Some(self.item.clone())) |
| } |
| } |