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use crate::lock::BiLock;
use core::fmt;
use futures_core::ready;
use futures_core::task::{Context, Poll};
use futures_io::{AsyncRead, AsyncWrite, IoSlice, IoSliceMut};
use std::io;
use std::pin::Pin;
/// The readable half of an object returned from `AsyncRead::split`.
#[derive(Debug)]
pub struct ReadHalf<T> {
handle: BiLock<T>,
}
/// The writable half of an object returned from `AsyncRead::split`.
#[derive(Debug)]
pub struct WriteHalf<T> {
handle: BiLock<T>,
}
fn lock_and_then<T, U, E, F>(lock: &BiLock<T>, cx: &mut Context<'_>, f: F) -> Poll<Result<U, E>>
where
F: FnOnce(Pin<&mut T>, &mut Context<'_>) -> Poll<Result<U, E>>,
{
let mut l = ready!(lock.poll_lock(cx));
f(l.as_pin_mut(), cx)
}
pub(super) fn split<T: AsyncRead + AsyncWrite>(t: T) -> (ReadHalf<T>, WriteHalf<T>) {
let (a, b) = BiLock::new(t);
(ReadHalf { handle: a }, WriteHalf { handle: b })
}
impl<T: Unpin> ReadHalf<T> {
/// Attempts to put the two "halves" of a split `AsyncRead + AsyncWrite` back
/// together. Succeeds only if the `ReadHalf<T>` and `WriteHalf<T>` are
/// a matching pair originating from the same call to `AsyncReadExt::split`.
pub fn reunite(self, other: WriteHalf<T>) -> Result<T, ReuniteError<T>> {
self.handle
.reunite(other.handle)
.map_err(|err| ReuniteError(ReadHalf { handle: err.0 }, WriteHalf { handle: err.1 }))
}
}
impl<T: Unpin> WriteHalf<T> {
/// Attempts to put the two "halves" of a split `AsyncRead + AsyncWrite` back
/// together. Succeeds only if the `ReadHalf<T>` and `WriteHalf<T>` are
/// a matching pair originating from the same call to `AsyncReadExt::split`.
pub fn reunite(self, other: ReadHalf<T>) -> Result<T, ReuniteError<T>> {
other.reunite(self)
}
}
impl<R: AsyncRead> AsyncRead for ReadHalf<R> {
fn poll_read(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut [u8],
) -> Poll<io::Result<usize>> {
lock_and_then(&self.handle, cx, |l, cx| l.poll_read(cx, buf))
}
fn poll_read_vectored(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
bufs: &mut [IoSliceMut<'_>],
) -> Poll<io::Result<usize>> {
lock_and_then(&self.handle, cx, |l, cx| l.poll_read_vectored(cx, bufs))
}
}
impl<W: AsyncWrite> AsyncWrite for WriteHalf<W> {
fn poll_write(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &[u8],
) -> Poll<io::Result<usize>> {
lock_and_then(&self.handle, cx, |l, cx| l.poll_write(cx, buf))
}
fn poll_write_vectored(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
bufs: &[IoSlice<'_>],
) -> Poll<io::Result<usize>> {
lock_and_then(&self.handle, cx, |l, cx| l.poll_write_vectored(cx, bufs))
}
fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
lock_and_then(&self.handle, cx, |l, cx| l.poll_flush(cx))
}
fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
lock_and_then(&self.handle, cx, |l, cx| l.poll_close(cx))
}
}
/// Error indicating a `ReadHalf<T>` and `WriteHalf<T>` were not two halves
/// of a `AsyncRead + AsyncWrite`, and thus could not be `reunite`d.
pub struct ReuniteError<T>(pub ReadHalf<T>, pub WriteHalf<T>);
impl<T> fmt::Debug for ReuniteError<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_tuple("ReuniteError").field(&"...").finish()
}
}
impl<T> fmt::Display for ReuniteError<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "tried to reunite a ReadHalf and WriteHalf that don't form a pair")
}
}
#[cfg(feature = "std")]
impl<T: core::any::Any> std::error::Error for ReuniteError<T> {}