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use crate::io::AsyncWrite;
use pin_project_lite::pin_project;
use std::future::Future;
use std::io;
use std::marker::PhantomPinned;
use std::mem;
use std::pin::Pin;
use std::task::{Context, Poll};
pin_project! {
#[derive(Debug)]
#[must_use = "futures do nothing unless you `.await` or poll them"]
pub struct WriteAll<'a, W: ?Sized> {
writer: &'a mut W,
buf: &'a [u8],
// Make this future `!Unpin` for compatibility with async trait methods.
#[pin]
_pin: PhantomPinned,
}
}
pub(crate) fn write_all<'a, W>(writer: &'a mut W, buf: &'a [u8]) -> WriteAll<'a, W>
where
W: AsyncWrite + Unpin + ?Sized,
{
WriteAll {
writer,
buf,
_pin: PhantomPinned,
}
}
impl<W> Future for WriteAll<'_, W>
where
W: AsyncWrite + Unpin + ?Sized,
{
type Output = io::Result<()>;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
let me = self.project();
while !me.buf.is_empty() {
let n = ready!(Pin::new(&mut *me.writer).poll_write(cx, me.buf))?;
{
let (_, rest) = mem::take(&mut *me.buf).split_at(n);
*me.buf = rest;
}
if n == 0 {
return Poll::Ready(Err(io::ErrorKind::WriteZero.into()));
}
}
Poll::Ready(Ok(()))
}
}