1 use super::{copy_buf, BufReader, CopyBuf};
2 use futures_core::future::Future;
3 use futures_core::task::{Context, Poll};
4 use futures_io::{AsyncRead, AsyncWrite};
5 use pin_project_lite::pin_project;
6 use std::io;
7 use std::pin::Pin;
8
9 /// Creates a future which copies all the bytes from one object to another.
10 ///
11 /// The returned future will copy all the bytes read from this `AsyncRead` into the
12 /// `writer` specified. This future will only complete once the `reader` has hit
13 /// EOF and all bytes have been written to and flushed from the `writer`
14 /// provided.
15 ///
16 /// On success the number of bytes is returned.
17 ///
18 /// # Examples
19 ///
20 /// ```
21 /// # futures::executor::block_on(async {
22 /// use futures::io::{self, AsyncWriteExt, Cursor};
23 ///
24 /// let reader = Cursor::new([1, 2, 3, 4]);
25 /// let mut writer = Cursor::new(vec![0u8; 5]);
26 ///
27 /// let bytes = io::copy(reader, &mut writer).await?;
28 /// writer.close().await?;
29 ///
30 /// assert_eq!(bytes, 4);
31 /// assert_eq!(writer.into_inner(), [1, 2, 3, 4, 0]);
32 /// # Ok::<(), Box<dyn std::error::Error>>(()) }).unwrap();
33 /// ```
copy<R, W>(reader: R, writer: &mut W) -> Copy<'_, R, W> where R: AsyncRead, W: AsyncWrite + Unpin + ?Sized,34 pub fn copy<R, W>(reader: R, writer: &mut W) -> Copy<'_, R, W>
35 where
36 R: AsyncRead,
37 W: AsyncWrite + Unpin + ?Sized,
38 {
39 Copy { inner: copy_buf(BufReader::new(reader), writer) }
40 }
41
42 pin_project! {
43 /// Future for the [`copy()`] function.
44 #[derive(Debug)]
45 #[must_use = "futures do nothing unless you `.await` or poll them"]
46 pub struct Copy<'a, R, W: ?Sized> {
47 #[pin]
48 inner: CopyBuf<'a, BufReader<R>, W>,
49 }
50 }
51
52 impl<R: AsyncRead, W: AsyncWrite + Unpin + ?Sized> Future for Copy<'_, R, W> {
53 type Output = io::Result<u64>;
54
poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output>55 fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
56 self.project().inner.poll(cx)
57 }
58 }
59