1use super::assert_stream;
2use core::pin::Pin;
3use futures_core::stream::Stream;
4use futures_core::task::{Context, Poll};
5
6/// Stream for the [`iter`] function.
7#[derive(Debug, Clone)]
8#[must_use = "streams do nothing unless polled"]
9pub struct Iter<I> {
10 iter: I,
11}
12
13impl<I> Iter<I> {
14 /// Acquires a reference to the underlying iterator that this stream is pulling from.
15 pub fn get_ref(&self) -> &I {
16 &self.iter
17 }
18
19 /// Acquires a mutable reference to the underlying iterator that this stream is pulling from.
20 pub fn get_mut(&mut self) -> &mut I {
21 &mut self.iter
22 }
23
24 /// Consumes this stream, returning the underlying iterator.
25 pub fn into_inner(self) -> I {
26 self.iter
27 }
28}
29
30impl<I> Unpin for Iter<I> {}
31
32/// Converts an `Iterator` into a `Stream` which is always ready
33/// to yield the next value.
34///
35/// Iterators in Rust don't express the ability to block, so this adapter
36/// simply always calls `iter.next()` and returns that.
37///
38/// ```
39/// # futures::executor::block_on(async {
40/// use futures::stream::{self, StreamExt};
41///
42/// let stream = stream::iter(vec![17, 19]);
43/// assert_eq!(vec![17, 19], stream.collect::<Vec<i32>>().await);
44/// # });
45/// ```
46pub fn iter<I>(i: I) -> Iter<I::IntoIter>
47where
48 I: IntoIterator,
49{
50 assert_stream::<I::Item, _>(Iter { iter: i.into_iter() })
51}
52
53impl<I> Stream for Iter<I>
54where
55 I: Iterator,
56{
57 type Item = I::Item;
58
59 fn poll_next(mut self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Option<I::Item>> {
60 Poll::Ready(self.iter.next())
61 }
62
63 fn size_hint(&self) -> (usize, Option<usize>) {
64 self.iter.size_hint()
65 }
66}
67