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use bytes::BufMut;
use std::future::Future;
use std::io;
use std::pin::Pin;
use std::task::{Context, Poll};
use tokio::io::AsyncRead;
/// Read data from an `AsyncRead` into an implementer of the [`Buf`] trait.
///
/// [`Buf`]: bytes::Buf
///
/// # Example
///
/// ```
/// use bytes::{Bytes, BytesMut};
/// use tokio::stream;
/// use tokio::io::Result;
/// use tokio_util::io::{StreamReader, read_buf};
/// # #[tokio::main]
/// # async fn main() -> std::io::Result<()> {
///
/// // Create a reader from an iterator. This particular reader will always be
/// // ready.
/// let mut read = StreamReader::new(stream::iter(vec![Result::Ok(Bytes::from_static(&[0, 1, 2, 3]))]));
///
/// let mut buf = BytesMut::new();
/// let mut reads = 0;
///
/// loop {
/// reads += 1;
/// let n = read_buf(&mut read, &mut buf).await?;
///
/// if n == 0 {
/// break;
/// }
/// }
///
/// // one or more reads might be necessary.
/// assert!(reads >= 1);
/// assert_eq!(&buf[..], &[0, 1, 2, 3]);
/// # Ok(())
/// # }
/// ```
pub async fn read_buf<R, B>(read: &mut R, buf: &mut B) -> io::Result<usize>
where
R: AsyncRead + Unpin,
B: BufMut,
{
return ReadBufFn(read, buf).await;
struct ReadBufFn<'a, R, B>(&'a mut R, &'a mut B);
impl<'a, R, B> Future for ReadBufFn<'a, R, B>
where
R: AsyncRead + Unpin,
B: BufMut,
{
type Output = io::Result<usize>;
fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
let this = &mut *self;
crate::util::poll_read_buf(Pin::new(this.0), cx, this.1)
}
}
}
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