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use futures_core::future::Future;
use futures_core::ready;
use futures_core::task::{Context, Poll};
use futures_io::AsyncWrite;
use std::io;
use std::mem;
use std::pin::Pin;
/// Future for the [`write_all`](super::AsyncWriteExt::write_all) method.
#[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],
}
impl<W: ?Sized + Unpin> Unpin for WriteAll<'_, W> {}
impl<'a, W: AsyncWrite + ?Sized + Unpin> WriteAll<'a, W> {
pub(super) fn new(writer: &'a mut W, buf: &'a [u8]) -> Self {
Self { writer, buf }
}
}
impl<W: AsyncWrite + ?Sized + Unpin> Future for WriteAll<'_, W> {
type Output = io::Result<()>;
fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
let this = &mut *self;
while !this.buf.is_empty() {
let n = ready!(Pin::new(&mut this.writer).poll_write(cx, this.buf))?;
{
let (_, rest) = mem::take(&mut this.buf).split_at(n);
this.buf = rest;
}
if n == 0 {
return Poll::Ready(Err(io::ErrorKind::WriteZero.into()));
}
}
Poll::Ready(Ok(()))
}
}