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use crate::io::AsyncBufRead;
use crate::util::memchr;
use pin_project_lite::pin_project;
use std::future::Future;
use std::io;
use std::marker::PhantomPinned;
use std::mem;
use std::pin::Pin;
use std::task::{Context, Poll};
pin_project! {
/// Future for the [`read_until`](crate::io::AsyncBufReadExt::read_until) method.
/// The delimiter is included in the resulting vector.
#[derive(Debug)]
#[must_use = "futures do nothing unless you `.await` or poll them"]
pub struct ReadUntil<'a, R: ?Sized> {
reader: &'a mut R,
delimiter: u8,
buf: &'a mut Vec<u8>,
// The number of bytes appended to buf. This can be less than buf.len() if
// the buffer was not empty when the operation was started.
read: usize,
// Make this future `!Unpin` for compatibility with async trait methods.
#[pin]
_pin: PhantomPinned,
}
}
pub(crate) fn read_until<'a, R>(
reader: &'a mut R,
delimiter: u8,
buf: &'a mut Vec<u8>,
) -> ReadUntil<'a, R>
where
R: AsyncBufRead + ?Sized + Unpin,
{
ReadUntil {
reader,
delimiter,
buf,
read: 0,
_pin: PhantomPinned,
}
}
pub(super) fn read_until_internal<R: AsyncBufRead + ?Sized>(
mut reader: Pin<&mut R>,
cx: &mut Context<'_>,
delimiter: u8,
buf: &mut Vec<u8>,
read: &mut usize,
) -> Poll<io::Result<usize>> {
loop {
let (done, used) = {
let available = ready!(reader.as_mut().poll_fill_buf(cx))?;
if let Some(i) = memchr::memchr(delimiter, available) {
buf.extend_from_slice(&available[..=i]);
(true, i + 1)
} else {
buf.extend_from_slice(available);
(false, available.len())
}
};
reader.as_mut().consume(used);
*read += used;
if done || used == 0 {
return Poll::Ready(Ok(mem::replace(read, 0)));
}
}
}
impl<R: AsyncBufRead + ?Sized + Unpin> Future for ReadUntil<'_, R> {
type Output = io::Result<usize>;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
let me = self.project();
read_until_internal(Pin::new(*me.reader), cx, *me.delimiter, me.buf, me.read)
}
}