async_std/stream/stream/
filter_map.rs

1use core::pin::Pin;
2use core::task::{Context, Poll};
3
4use pin_project_lite::pin_project;
5
6use crate::stream::Stream;
7
8pin_project! {
9    #[derive(Debug)]
10    pub struct FilterMap<S, F> {
11        #[pin]
12        stream: S,
13        f: F,
14    }
15}
16
17impl<S, F> FilterMap<S, F> {
18    pub(crate) fn new(stream: S, f: F) -> Self {
19        Self { stream, f }
20    }
21}
22
23impl<S, F, B> Stream for FilterMap<S, F>
24where
25    S: Stream,
26    F: FnMut(S::Item) -> Option<B>,
27{
28    type Item = B;
29
30    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
31        let this = self.project();
32        let next = futures_core::ready!(this.stream.poll_next(cx));
33        match next {
34            Some(v) => match (this.f)(v) {
35                Some(b) => Poll::Ready(Some(b)),
36                None => {
37                    cx.waker().wake_by_ref();
38                    Poll::Pending
39                }
40            },
41            None => Poll::Ready(None),
42        }
43    }
44}
async_std/stream/stream/filter_map.rs

async_std/stream/stream/
filter_map.rs
