mirror of
https://github.com/tokio-rs/tokio.git
synced 2026-08-22 00:00:11 +02:00
Eliza Weisman
8aa520e2bd
The standard library's `io` module has small utilities such as `repeat`, `empty`, and `sink`, which return `Read` and `Write` implementations. These can come in handy in some circiumstances. `tokio::io` has no equivalents that implement `AsyncRead`/`AsyncWrite`. This commit adds `repeat`, `empty`, and `sink` helpers to `tokio::io`.
68 lines
1.5 KiB
Rust
68 lines
1.5 KiB
Rust
use crate::AsyncRead;
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use std::io;
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use std::pin::Pin;
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use std::task::{Context, Poll};
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/// An async reader which yields one byte over and over and over and over and
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/// over and...
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///
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/// This struct is generally created by calling [`repeat`][repeat]. Please
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/// see the documentation of `repeat()` for more details.
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///
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/// This is an asynchronous version of [`std::io::Repeat`][std].
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///
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/// [repeat]: fn.repeat.html
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/// [std]: https://doc.rust-lang.org/std/io/struct.Repeat.html
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#[derive(Debug)]
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pub struct Repeat {
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byte: u8,
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}
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/// Creates an instance of an async reader that infinitely repeats one byte.
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///
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/// All reads from this reader will succeed by filling the specified buffer with
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/// the given byte.
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///
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/// This is an asynchronous version of [`std::io::repeat`][std].
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///
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/// # Examples
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///
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/// ```
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/// # use tokio_io::{self as io, AsyncReadExt};
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/// # async fn dox() {
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/// let mut buffer = [0; 3];
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/// io::repeat(0b101).read_exact(&mut buffer).await.unwrap();
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/// assert_eq!(buffer, [0b101, 0b101, 0b101]);
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/// # }
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/// ```
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///
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/// [std]: https://doc.rust-lang.org/std/io/fn.repeat.html
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pub fn repeat(byte: u8) -> Repeat {
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Repeat { byte }
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}
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impl AsyncRead for Repeat {
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#[inline]
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fn poll_read(
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self: Pin<&mut Self>,
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_: &mut Context<'_>,
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buf: &mut [u8],
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) -> Poll<io::Result<usize>> {
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for byte in &mut *buf {
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*byte = self.byte;
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}
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Poll::Ready(Ok(buf.len()))
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn assert_unpin() {
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crate::is_unpin::<Repeat>();
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}
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}
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