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")
67            .field("iter", &self.iter)
68            .finish()
69    }
70}
async_iter_ext/combinator/map.rs

async_iter_ext/combinator/
map.rs
