1use crate::io::AsyncWrite;
2
3use pin_project_lite::pin_project;
4use std::future::Future;
5use std::io;
6use std::marker::PhantomPinned;
7use std::pin::Pin;
8use std::task::{Context, Poll};
9
10pin_project! {
11 /// A future used to fully flush an I/O object.
12 ///
13 /// Created by the [`AsyncWriteExt::flush`][flush] function.
14 ///
15 /// [flush]: crate::io::AsyncWriteExt::flush
16 #[derive(Debug)]
17 #[must_use = "futures do nothing unless you `.await` or poll them"]
18 pub struct Flush<'a, A: ?Sized> {
19 a: &'a mut A,
20 // Make this future `!Unpin` for compatibility with async trait methods.
21 #[pin]
22 _pin: PhantomPinned,
23 }
24}
25
26/// Creates a future which will entirely flush an I/O object.
27pub(super) fn flush<A>(a: &mut A) -> Flush<'_, A>
28where
29 A: AsyncWrite + Unpin + ?Sized,
30{
31 Flush {
32 a,
33 _pin: PhantomPinned,
34 }
35}
36
37impl<A> Future for Flush<'_, A>
38where
39 A: AsyncWrite + Unpin + ?Sized,
40{
41 type Output = io::Result<()>;
42
43 fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
44 let me: Projection<'_, '_, A> = self.project();
45 Pin::new(&mut *me.a).poll_flush(cx)
46 }
47}
48