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use bytes::{Bytes, BytesMut};
use futures_core::stream::Stream;
use pin_project_lite::pin_project;
use std::pin::Pin;
use std::task::{Context, Poll};
use tokio::io::AsyncRead;
const CAPACITY: usize = 4096;
pin_project! {
#[derive(Debug)]
pub struct ReaderStream<R> {
#[pin]
reader: Option<R>,
buf: BytesMut,
}
}
impl<R: AsyncRead> ReaderStream<R> {
pub fn new(reader: R) -> Self {
ReaderStream {
reader: Some(reader),
buf: BytesMut::new(),
}
}
}
impl<R: AsyncRead> Stream for ReaderStream<R> {
type Item = std::io::Result<Bytes>;
fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
use crate::util::poll_read_buf;
let mut this = self.as_mut().project();
let reader = match this.reader.as_pin_mut() {
Some(r) => r,
None => return Poll::Ready(None),
};
if this.buf.capacity() == 0 {
this.buf.reserve(CAPACITY);
}
match poll_read_buf(reader, cx, &mut this.buf) {
Poll::Pending => Poll::Pending,
Poll::Ready(Err(err)) => {
self.project().reader.set(None);
Poll::Ready(Some(Err(err)))
}
Poll::Ready(Ok(0)) => {
self.project().reader.set(None);
Poll::Ready(None)
}
Poll::Ready(Ok(_)) => {
let chunk = this.buf.split();
Poll::Ready(Some(Ok(chunk.freeze())))
}
}
}
}