59 lines
1.7 KiB
Rust
59 lines
1.7 KiB
Rust
use super::{copy_buf, BufReader, CopyBuf};
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use futures_core::future::Future;
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use futures_core::task::{Context, Poll};
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use futures_io::{AsyncRead, AsyncWrite};
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use pin_project_lite::pin_project;
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use std::io;
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use std::pin::Pin;
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/// Creates a future which copies all the bytes from one object to another.
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///
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/// The returned future will copy all the bytes read from this `AsyncRead` into the
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/// `writer` specified. This future will only complete once the `reader` has hit
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/// EOF and all bytes have been written to and flushed from the `writer`
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/// provided.
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///
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/// On success the number of bytes is returned.
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///
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/// # Examples
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///
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/// ```
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/// # futures::executor::block_on(async {
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/// use futures::io::{self, AsyncWriteExt, Cursor};
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///
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/// let reader = Cursor::new([1, 2, 3, 4]);
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/// let mut writer = Cursor::new(vec![0u8; 5]);
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///
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/// let bytes = io::copy(reader, &mut writer).await?;
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/// writer.close().await?;
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///
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/// assert_eq!(bytes, 4);
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/// assert_eq!(writer.into_inner(), [1, 2, 3, 4, 0]);
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/// # Ok::<(), Box<dyn std::error::Error>>(()) }).unwrap();
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/// ```
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pub fn copy<R, W>(reader: R, writer: &mut W) -> Copy<'_, R, W>
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where
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R: AsyncRead,
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W: AsyncWrite + Unpin + ?Sized,
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{
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Copy { inner: copy_buf(BufReader::new(reader), writer) }
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}
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pin_project! {
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/// Future for the [`copy()`] function.
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#[derive(Debug)]
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#[must_use = "futures do nothing unless you `.await` or poll them"]
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pub struct Copy<'a, R, W: ?Sized> {
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#[pin]
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inner: CopyBuf<'a, BufReader<R>, W>,
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}
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}
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impl<R: AsyncRead, W: AsyncWrite + Unpin + ?Sized> Future for Copy<'_, R, W> {
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type Output = io::Result<u64>;
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fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
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self.project().inner.poll(cx)
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}
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}
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