mirror of
https://github.com/tokio-rs/tokio.git
synced 2026-08-20 00:00:08 +02:00
Lucio Franco
8efa62013b
This change removes all references to `Stream` from within the `tokio` crate and moves them into a new `tokio-stream` crate. Most types have had their `impl Stream` removed as well in-favor of their inherent methods. Closes #2870
53 lines
1.2 KiB
Rust
53 lines
1.2 KiB
Rust
use crate::{Iter, Stream};
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use core::option;
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use core::pin::Pin;
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use core::task::{Context, Poll};
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/// Stream for the [`once`](fn@once) function.
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#[derive(Debug)]
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#[must_use = "streams do nothing unless polled"]
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pub struct Once<T> {
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iter: Iter<option::IntoIter<T>>,
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}
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impl<I> Unpin for Once<I> {}
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/// Creates a stream that emits an element exactly once.
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///
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/// The returned stream is immediately ready and emits the provided value once.
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///
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/// # Examples
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///
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/// ```
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/// use tokio_stream::{self as stream, StreamExt};
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///
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/// #[tokio::main]
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/// async fn main() {
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/// // one is the loneliest number
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/// let mut one = stream::once(1);
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///
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/// assert_eq!(Some(1), one.next().await);
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///
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/// // just one, that's all we get
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/// assert_eq!(None, one.next().await);
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/// }
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/// ```
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pub fn once<T>(value: T) -> Once<T> {
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Once {
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iter: crate::iter(Some(value).into_iter()),
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}
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}
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impl<T> Stream for Once<T> {
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type Item = T;
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fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<T>> {
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Pin::new(&mut self.iter).poll_next(cx)
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}
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fn size_hint(&self) -> (usize, Option<usize>) {
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self.iter.size_hint()
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}
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}
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