60 lines
1.9 KiB
Rust
60 lines
1.9 KiB
Rust
use super::read_to_end::read_to_end_internal;
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use futures_core::future::Future;
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use futures_core::ready;
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use futures_core::task::{Context, Poll};
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use futures_io::AsyncRead;
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use std::pin::Pin;
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use std::vec::Vec;
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use std::{io, mem, str};
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/// Future for the [`read_to_string`](super::AsyncReadExt::read_to_string) method.
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#[derive(Debug)]
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#[must_use = "futures do nothing unless you `.await` or poll them"]
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pub struct ReadToString<'a, R: ?Sized> {
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reader: &'a mut R,
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buf: &'a mut String,
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bytes: Vec<u8>,
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start_len: usize,
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}
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impl<R: ?Sized + Unpin> Unpin for ReadToString<'_, R> {}
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impl<'a, R: AsyncRead + ?Sized + Unpin> ReadToString<'a, R> {
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pub(super) fn new(reader: &'a mut R, buf: &'a mut String) -> Self {
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let start_len = buf.len();
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Self { reader, bytes: mem::replace(buf, String::new()).into_bytes(), buf, start_len }
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}
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}
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fn read_to_string_internal<R: AsyncRead + ?Sized>(
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reader: Pin<&mut R>,
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cx: &mut Context<'_>,
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buf: &mut String,
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bytes: &mut Vec<u8>,
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start_len: usize,
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) -> Poll<io::Result<usize>> {
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let ret = ready!(read_to_end_internal(reader, cx, bytes, start_len));
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if str::from_utf8(bytes).is_err() {
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Poll::Ready(ret.and_then(|_| {
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Err(io::Error::new(io::ErrorKind::InvalidData, "stream did not contain valid UTF-8"))
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}))
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} else {
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debug_assert!(buf.is_empty());
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// Safety: `bytes` is a valid UTF-8 because `str::from_utf8` returned `Ok`.
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mem::swap(unsafe { buf.as_mut_vec() }, bytes);
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Poll::Ready(ret)
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}
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}
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impl<A> Future for ReadToString<'_, A>
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where
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A: AsyncRead + ?Sized + Unpin,
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{
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type Output = io::Result<usize>;
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fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
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let Self { reader, buf, bytes, start_len } = &mut *self;
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read_to_string_internal(Pin::new(reader), cx, buf, bytes, *start_len)
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}
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}
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