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