broker_tokio/io/util/
repeat.rs

1use crate::io::AsyncRead;
2
3use std::io;
4use std::pin::Pin;
5use std::task::{Context, Poll};
6
7cfg_io_util! {
8    /// An async reader which yields one byte over and over and over and over and
9    /// over and...
10    ///
11    /// This struct is generally created by calling [`repeat`][repeat]. Please
12    /// see the documentation of `repeat()` for more details.
13    ///
14    /// This is an asynchronous version of [`std::io::Repeat`][std].
15    ///
16    /// [repeat]: fn.repeat.html
17    /// [std]: std::io::Repeat
18    #[derive(Debug)]
19    pub struct Repeat {
20        byte: u8,
21    }
22
23    /// Creates an instance of an async reader that infinitely repeats one byte.
24    ///
25    /// All reads from this reader will succeed by filling the specified buffer with
26    /// the given byte.
27    ///
28    /// This is an asynchronous version of [`std::io::repeat`][std].
29    ///
30    /// [std]: std::io::repeat
31    ///
32    /// # Examples
33    ///
34    /// ```
35    /// use tokio::io::{self, AsyncReadExt};
36    ///
37    /// #[tokio::main]
38    /// async fn main() {
39    ///     let mut buffer = [0; 3];
40    ///     io::repeat(0b101).read_exact(&mut buffer).await.unwrap();
41    ///     assert_eq!(buffer, [0b101, 0b101, 0b101]);
42    /// }
43    /// ```
44    pub fn repeat(byte: u8) -> Repeat {
45        Repeat { byte }
46    }
47}
48
49impl AsyncRead for Repeat {
50    #[inline]
51    fn poll_read(
52        self: Pin<&mut Self>,
53        _: &mut Context<'_>,
54        buf: &mut [u8],
55    ) -> Poll<io::Result<usize>> {
56        for byte in &mut *buf {
57            *byte = self.byte;
58        }
59        Poll::Ready(Ok(buf.len()))
60    }
61}
62
63#[cfg(test)]
64mod tests {
65    use super::*;
66
67    #[test]
68    fn assert_unpin() {
69        crate::is_unpin::<Repeat>();
70    }
71}
broker_tokio/io/util/repeat.rs

broker_tokio/io/util/
repeat.rs
