1use std::mem;
2use std::pin::Pin;
3use std::str;
4use std::future::Future;
5
6use super::read_until_internal;
7use crate::io::{self, BufRead};
8use crate::task::{Context, Poll};
9
10#[doc(hidden)]
11#[allow(missing_debug_implementations)]
12pub struct ReadLineFuture<'a, T: Unpin + ?Sized> {
13 pub(crate) reader: &'a mut T,
14 pub(crate) buf: &'a mut String,
15 pub(crate) bytes: Vec<u8>,
16 pub(crate) read: usize,
17}
18
19impl<T: BufRead + Unpin + ?Sized> Future for ReadLineFuture<'_, T> {
20 type Output = io::Result<usize>;
21
22 fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
23 let Self {
24 reader,
25 buf,
26 bytes,
27 read,
28 } = &mut *self;
29 let reader = Pin::new(reader);
30
31 let ret = futures_core::ready!(read_until_internal(reader, cx, b'\n', bytes, read));
32 if str::from_utf8(&bytes).is_err() {
33 Poll::Ready(ret.and_then(|_| {
34 Err(io::Error::new(
35 io::ErrorKind::InvalidData,
36 "stream did not contain valid UTF-8",
37 ))
38 }))
39 } else {
40 #[allow(clippy::debug_assert_with_mut_call)]
41 {
42 debug_assert!(buf.is_empty());
43 debug_assert_eq!(*read, 0);
44 }
45
46 // Safety: `bytes` is a valid UTF-8 because `str::from_utf8` returned `Ok`.
47 mem::swap(unsafe { buf.as_mut_vec() }, bytes);
48 Poll::Ready(ret)
49 }
50 }
51}
52