1 use futures_core::future::Future;
2 use futures_core::ready;
3 use futures_core::task::{Context, Poll};
4 use futures_io::AsyncWrite;
5 use std::io;
6 use std::mem;
7 use std::pin::Pin;
8 
9 /// Future for the [`write_all`](super::AsyncWriteExt::write_all) method.
10 #[derive(Debug)]
11 #[must_use = "futures do nothing unless you `.await` or poll them"]
12 pub struct WriteAll<'a, W: ?Sized> {
13     writer: &'a mut W,
14     buf: &'a [u8],
15 }
16 
17 impl<W: ?Sized + Unpin> Unpin for WriteAll<'_, W> {}
18 
19 impl<'a, W: AsyncWrite + ?Sized + Unpin> WriteAll<'a, W> {
new(writer: &'a mut W, buf: &'a [u8]) -> Self20     pub(super) fn new(writer: &'a mut W, buf: &'a [u8]) -> Self {
21         Self { writer, buf }
22     }
23 }
24 
25 impl<W: AsyncWrite + ?Sized + Unpin> Future for WriteAll<'_, W> {
26     type Output = io::Result<()>;
27 
poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>>28     fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
29         let this = &mut *self;
30         while !this.buf.is_empty() {
31             let n = ready!(Pin::new(&mut this.writer).poll_write(cx, this.buf))?;
32             {
33                 let (_, rest) = mem::take(&mut this.buf).split_at(n);
34                 this.buf = rest;
35             }
36             if n == 0 {
37                 return Poll::Ready(Err(io::ErrorKind::WriteZero.into()));
38             }
39         }
40 
41         Poll::Ready(Ok(()))
42     }
43 }
44