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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::pin::Pin;
use std::task::{Context, Poll};
pin_project! {
/// A future to write some of the buffer to an `AsyncWrite`.
#[derive(Debug)]
#[must_use = "futures do nothing unless you `.await` or poll them"]
pub struct Write<'a, W: ?Sized> {
writer: &'a mut W,
buf: &'a [u8],
// Make this future `!Unpin` for compatibility with async trait methods.
#[pin]
_pin: PhantomPinned,
}
}
/// Tries to write some bytes from the given `buf` to the writer in an
/// asynchronous manner, returning a future.
pub(crate) fn write<'a, W>(writer: &'a mut W, buf: &'a [u8]) -> Write<'a, W>
where
W: AsyncWrite + Unpin + ?Sized,
{
Write {
writer,
buf,
_pin: PhantomPinned,
}
}
impl<W> Future for Write<'_, W>
where
W: AsyncWrite + Unpin + ?Sized,
{
type Output = io::Result<usize>;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<usize>> {
let me = self.project();
Pin::new(&mut *me.writer).poll_write(cx, me.buf)
}
}