async_std/io/buf_read/
read_line.rs

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}
async_std/io/buf_read/read_line.rs

async_std/io/buf_read/
read_line.rs
