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use super::read_until::read_until_internal;
use futures_core::future::Future;
use futures_core::ready;
use futures_core::task::{Context, Poll};
use futures_io::AsyncBufRead;
use std::io;
use std::mem;
use std::pin::Pin;
use std::str;
/// Future for the [`read_line`](super::AsyncBufReadExt::read_line) method.
#[derive(Debug)]
#[must_use = "futures do nothing unless you `.await` or poll them"]
pub struct ReadLine<'a, R: ?Sized> {
reader: &'a mut R,
buf: &'a mut String,
bytes: Vec<u8>,
read: usize,
}
impl<R: ?Sized + Unpin> Unpin for ReadLine<'_, R> {}
impl<'a, R: AsyncBufRead + ?Sized + Unpin> ReadLine<'a, R> {
pub(super) fn new(reader: &'a mut R, buf: &'a mut String) -> Self {
Self { reader, bytes: mem::take(buf).into_bytes(), buf, read: 0 }
}
}
pub(super) fn read_line_internal<R: AsyncBufRead + ?Sized>(
reader: Pin<&mut R>,
cx: &mut Context<'_>,
buf: &mut String,
bytes: &mut Vec<u8>,
read: &mut usize,
) -> Poll<io::Result<usize>> {
let ret = ready!(read_until_internal(reader, cx, b'\n', bytes, read));
if str::from_utf8(bytes).is_err() {
Poll::Ready(ret.and_then(|_| {
Err(io::Error::new(io::ErrorKind::InvalidData, "stream did not contain valid UTF-8"))
}))
} else {
debug_assert!(buf.is_empty());
debug_assert_eq!(*read, 0);
// Safety: `bytes` is a valid UTF-8 because `str::from_utf8` returned `Ok`.
mem::swap(unsafe { buf.as_mut_vec() }, bytes);
Poll::Ready(ret)
}
}
impl<R: AsyncBufRead + ?Sized + Unpin> Future for ReadLine<'_, R> {
type Output = io::Result<usize>;
fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
let Self { reader, buf, bytes, read } = &mut *self;
read_line_internal(Pin::new(reader), cx, buf, bytes, read)
}
}