tokio_stream/
iter.rs

1use crate::Stream;
2
3use core::pin::Pin;
4use core::task::{Context, Poll};
5
6/// Stream for the [`iter`](fn@iter) function.
7#[derive(Debug)]
8#[must_use = "streams do nothing unless polled"]
9pub struct Iter<I> {
10    iter: I,
11    yield_amt: usize,
12}
13
14impl<I> Unpin for Iter<I> {}
15
16/// Converts an `Iterator` into a `Stream` which is always ready
17/// to yield the next value.
18///
19/// Iterators in Rust don't express the ability to block, so this adapter
20/// simply always calls `iter.next()` and returns that.
21///
22/// ```
23/// # async fn dox() {
24/// use tokio_stream::{self as stream, StreamExt};
25///
26/// let mut stream = stream::iter(vec![17, 19]);
27///
28/// assert_eq!(stream.next().await, Some(17));
29/// assert_eq!(stream.next().await, Some(19));
30/// assert_eq!(stream.next().await, None);
31/// # }
32/// ```
33pub fn iter<I>(i: I) -> Iter<I::IntoIter>
34where
35    I: IntoIterator,
36{
37    Iter {
38        iter: i.into_iter(),
39        yield_amt: 0,
40    }
41}
42
43impl<I> Stream for Iter<I>
44where
45    I: Iterator,
46{
47    type Item = I::Item;
48
49    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<I::Item>> {
50        // TODO: add coop back
51        if self.yield_amt >= 32 {
52            self.yield_amt = 0;
53
54            cx.waker().wake_by_ref();
55
56            Poll::Pending
57        } else {
58            self.yield_amt += 1;
59
60            Poll::Ready(self.iter.next())
61        }
62    }
63
64    fn size_hint(&self) -> (usize, Option<usize>) {
65        self.iter.size_hint()
66    }
67}
tokio_stream/iter.rs

tokio_stream/
iter.rs
