async_iter_ext/combinator/
map.rs

1use std::{
2  fmt::{Debug, Formatter},
3  pin::Pin,
4  task::{Context, Poll},
5  vec::IntoIter,
6};
7
8use crate::iter::{
9  AsyncIterator,
10  sync_iter::{PollSyncIter, SyncIter},
11};
12
13#[must_use = "async iterator combinators are lazy and do nothing unless consumed"]
14pub struct AsyncMap<I, F> {
15  pub(crate) iter: I,
16  pub(crate) f: F,
17}
18
19impl<B, I, F, Fut> PollSyncIter for AsyncMap<I, F>
20where
21  I: AsyncIterator + Unpin,
22  F: FnMut(I::Item) -> Fut + Unpin + Send,
23  Fut: Future<Output = B> + Send,
24{
25}
26
27impl<B, I, F, Fut> Future for AsyncMap<I, F>
28where
29  I: AsyncIterator + Unpin,
30  F: FnMut(I::Item) -> Fut + Unpin + Send,
31  Fut: Future<Output = B> + Send,
32{
33  type Output = SyncIter<IntoIter<B>>;
34
35  fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
36    Self::poll_sync_iter(self, cx)
37  }
38}
39
40impl<B, I, F, Fut> AsyncIterator for AsyncMap<I, F>
41where
42  I: AsyncIterator,
43  F: FnMut(I::Item) -> Fut + Send,
44  Fut: Future<Output = B> + Send,
45{
46  type Item = B;
47
48  async fn next_async(&mut self) -> Option<Self::Item> {
49    if let Some(next) = self.iter.next_async().await {
50      Some((self.f)(next).await)
51    } else {
52      None
53    }
54  }
55
56  fn async_size_hint(&self) -> (usize, Option<usize>) {
57    self.iter.async_size_hint()
58  }
59}
60
61impl<I, F> Debug for AsyncMap<I, F>
62where
63  I: AsyncIterator + Debug,
64{
65  fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
66    f.debug_struct("AsyncMap").field("iter", &self.iter).finish()
67  }
68}
async_iter_ext/combinator/map.rs

async_iter_ext/combinator/
map.rs
