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use futures::executor;
use futures::stream::StreamExt;
use futures::AsyncRead;
use futures_codec::{Decoder, FramedRead, LinesCodec, BytesMut};
use std::io;
use std::pin::Pin;
use std::task::{Context, Poll};
// Sends two lines at once, then nothing else forever
struct MockBurstySender {
sent: bool,
}
impl AsyncRead for MockBurstySender {
fn poll_read(
mut self: Pin<&mut Self>,
_cx: &mut Context<'_>,
buf: &mut [u8],
) -> Poll<io::Result<usize>> {
const MESSAGES: &'static [u8] = b"one\ntwo\n";
if !self.sent && buf.len() >= MESSAGES.len() {
self.sent = true;
buf[0..MESSAGES.len()].clone_from_slice(MESSAGES);
Poll::Ready(Ok(MESSAGES.len()))
} else {
Poll::Pending
}
}
}
#[test]
fn line_read_multi() {
let io = MockBurstySender { sent: false };
let mut framed = FramedRead::new(io, LinesCodec {});
let one = executor::block_on(framed.next()).unwrap().unwrap();
assert_eq!(one, "one\n");
let two = executor::block_on(framed.next()).unwrap().unwrap();
assert_eq!(two, "two\n");
}
struct OneByteAtATime<'a> {
input: &'a [u8],
}
impl AsyncRead for OneByteAtATime<'_> {
fn poll_read(
mut self: Pin<&mut Self>,
_cx: &mut Context<'_>,
buf: &mut [u8],
) -> Poll<io::Result<usize>> {
if self.input.is_empty() {
Poll::Ready(Ok(0))
} else {
buf[0] = self.input[0];
self.input = &self.input[1..];
Poll::Ready(Ok(1))
}
}
}
/// A decoder that only returns `a` characters from the input.
struct AllTheAs;
impl Decoder for AllTheAs {
type Item = char;
type Error = io::Error;
fn decode(&mut self, src: &mut BytesMut) -> Result<Option<Self::Item>, Self::Error> {
while !src.is_empty() {
let buf = src.split_to(1);
let c = char::from(buf[0]);
if c == 'a' {
return Ok(Some(c));
}
}
Ok(None)
}
}
#[test]
fn read_few_messages() {
let string: &[u8] = b"aabbbabbbabbbabb";
let input = OneByteAtATime { input: string };
let mut framed = FramedRead::new(input, AllTheAs);
for _ in 0..5 {
let item = executor::block_on(framed.next()).unwrap().unwrap();
assert_eq!(item, 'a');
}
}
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