async_std/stream/stream/
skip.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    /// A stream to skip first n elements of another stream.
10    ///
11    /// This `struct` is created by the [`skip`] method on [`Stream`]. See its
12    /// documentation for more.
13    ///
14    /// [`skip`]: trait.Stream.html#method.skip
15    /// [`Stream`]: trait.Stream.html
16    #[derive(Debug)]
17    pub struct Skip<S> {
18        #[pin]
19        stream: S,
20        n: usize,
21    }
22}
23
24impl<S> Skip<S> {
25    pub(crate) fn new(stream: S, n: usize) -> Self {
26        Self { stream, n }
27    }
28}
29
30impl<S> Stream for Skip<S>
31where
32    S: Stream,
33{
34    type Item = S::Item;
35
36    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
37        let mut this = self.project();
38        loop {
39            let next = futures_core::ready!(this.stream.as_mut().poll_next(cx));
40
41            match next {
42                Some(v) => match *this.n {
43                    0 => return Poll::Ready(Some(v)),
44                    _ => *this.n -= 1,
45                },
46                None => return Poll::Ready(None),
47            }
48        }
49    }
50}
async_std/stream/stream/skip.rs

async_std/stream/stream/
skip.rs
