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use core::future; use core::mem; use core::pin; use core::task; #[derive(Debug)] #[must_use = "futures do nothing unless you `.await` or poll them"] pub struct WriteAll<'a, A: ?Sized> { writer: &'a mut A, buffer: &'a [u8], } pub(crate) fn write_all<'a, A>(writer: &'a mut A, buffer: &'a [u8]) -> WriteAll<'a, A> where A: super::Write + Unpin + ?Sized, { WriteAll { writer, buffer } } impl<A> future::Future for WriteAll<'_, A> where A: super::Write + Unpin + ?Sized, { type Output = Result<(), A::Error>; fn poll(mut self: pin::Pin<&mut Self>, cx: &mut task::Context<'_>) -> task::Poll<Self::Output> { use super::Write; use super::WriteError; let this = &mut *self; while !this.buffer.is_empty() { let n = futures::ready!(pin::Pin::new(&mut this.writer).poll_write(cx, this.buffer))?; { let (_, rest) = mem::replace(&mut this.buffer, &[]).split_at(n); this.buffer = rest; } if n == 0 { return task::Poll::Ready(Err(A::Error::write_zero())); } } task::Poll::Ready(Ok(())) } }