1 use super::assert_stream;
2 use core::pin::Pin;
3 use futures_core::stream::Stream;
4 use futures_core::task::{Context, Poll};
5
6 /// Stream for the [`iter`] function.
7 #[derive(Debug, Clone)]
8 #[must_use = "streams do nothing unless polled"]
9 pub struct Iter<I> {
10 iter: I,
11 }
12
13 impl<I> Iter<I> {
14 /// Acquires a reference to the underlying iterator that this stream is pulling from.
get_ref(&self) -> &I15 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.
get_mut(&mut self) -> &mut I20 pub fn get_mut(&mut self) -> &mut I {
21 &mut self.iter
22 }
23
24 /// Consumes this stream, returning the underlying iterator.
into_inner(self) -> I25 pub fn into_inner(self) -> I {
26 self.iter
27 }
28 }
29
30 impl<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 /// ```
iter<I>(i: I) -> Iter<I::IntoIter> where I: IntoIterator,46 pub fn iter<I>(i: I) -> Iter<I::IntoIter>
47 where
48 I: IntoIterator,
49 {
50 assert_stream::<I::Item, _>(Iter { iter: i.into_iter() })
51 }
52
53 impl<I> Stream for Iter<I>
54 where
55 I: Iterator,
56 {
57 type Item = I::Item;
58
poll_next(mut self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Option<I::Item>>59 fn poll_next(mut self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Option<I::Item>> {
60 Poll::Ready(self.iter.next())
61 }
62
size_hint(&self) -> (usize, Option<usize>)63 fn size_hint(&self) -> (usize, Option<usize>) {
64 self.iter.size_hint()
65 }
66 }
67