broker_tokio/io/
seek.rs

1use crate::io::AsyncSeek;
2use std::future::Future;
3use std::io::{self, SeekFrom};
4use std::pin::Pin;
5use std::task::{Context, Poll};
6
7/// Future for the [`seek`](crate::io::AsyncSeekExt::seek) method.
8#[derive(Debug)]
9#[must_use = "futures do nothing unless you `.await` or poll them"]
10pub struct Seek<'a, S: ?Sized> {
11    seek: &'a mut S,
12    pos: Option<SeekFrom>,
13}
14
15pub(crate) fn seek<S>(seek: &mut S, pos: SeekFrom) -> Seek<'_, S>
16where
17    S: AsyncSeek + ?Sized + Unpin,
18{
19    Seek {
20        seek,
21        pos: Some(pos),
22    }
23}
24
25impl<S> Future for Seek<'_, S>
26where
27    S: AsyncSeek + ?Sized + Unpin,
28{
29    type Output = io::Result<u64>;
30
31    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
32        let me = &mut *self;
33        match me.pos {
34            Some(pos) => match Pin::new(&mut me.seek).start_seek(cx, pos) {
35                Poll::Ready(Ok(())) => {
36                    me.pos = None;
37                    Pin::new(&mut me.seek).poll_complete(cx)
38                }
39                Poll::Ready(Err(e)) => Poll::Ready(Err(e)),
40                Poll::Pending => Poll::Pending,
41            },
42            None => Pin::new(&mut me.seek).poll_complete(cx),
43        }
44    }
45}
46
47#[cfg(test)]
48mod tests {
49    use super::*;
50
51    #[test]
52    fn assert_unpin() {
53        use std::marker::PhantomPinned;
54        crate::is_unpin::<Seek<'_, PhantomPinned>>();
55    }
56}
broker_tokio/io/seek.rs

broker_tokio/io/
seek.rs
