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impl some traits for Either #1695

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Jul 1, 2019
Merged

impl some traits for Either #1695

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184 changes: 178 additions & 6 deletions futures-util/src/future/either.rs
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
use core::pin::Pin;
use core::task::{Context, Poll};
use futures_core::future::Future;
use futures_core::stream::Stream;
use futures_core::future::{FusedFuture, Future};
use futures_core::stream::{FusedStream, Stream};
use futures_sink::Sink;

/// Combines two different futures, streams, or sinks having the same associated types into a single
Expand Down Expand Up @@ -58,13 +58,26 @@ where
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<A::Output> {
unsafe {
match self.get_unchecked_mut() {
Either::Left(a) => Pin::new_unchecked(a).poll(cx),
Either::Right(b) => Pin::new_unchecked(b).poll(cx),
Either::Left(x) => Pin::new_unchecked(x).poll(cx),
Either::Right(x) => Pin::new_unchecked(x).poll(cx),
}
}
}
}

impl<A, B> FusedFuture for Either<A, B>
where
A: FusedFuture,
B: FusedFuture,
{
fn is_terminated(&self) -> bool {
match self {
Either::Left(x) => x.is_terminated(),
Either::Right(x) => x.is_terminated(),
}
}
}

impl<A, B> Stream for Either<A, B>
where
A: Stream,
Expand All @@ -75,13 +88,26 @@ where
fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<A::Item>> {
unsafe {
match self.get_unchecked_mut() {
Either::Left(a) => Pin::new_unchecked(a).poll_next(cx),
Either::Right(b) => Pin::new_unchecked(b).poll_next(cx),
Either::Left(x) => Pin::new_unchecked(x).poll_next(cx),
Either::Right(x) => Pin::new_unchecked(x).poll_next(cx),
}
}
}
}

impl<A, B> FusedStream for Either<A, B>
where
A: FusedStream,
B: FusedStream,
{
fn is_terminated(&self) -> bool {
match self {
Either::Left(x) => x.is_terminated(),
Either::Right(x) => x.is_terminated(),
}
}
}

impl<A, B, Item> Sink<Item> for Either<A, B>
where
A: Sink<Item>,
Expand Down Expand Up @@ -125,3 +151,149 @@ where
}
}
}

#[cfg(feature = "std")]
mod if_std {
use super::Either;
use core::pin::Pin;
use core::task::{Context, Poll};
use futures_io::{
AsyncBufRead, AsyncRead, AsyncSeek, AsyncWrite, Initializer, IoSlice, IoSliceMut, Result,
SeekFrom,
};

impl<A, B> AsyncRead for Either<A, B>
where
A: AsyncRead,
B: AsyncRead,
{
unsafe fn initializer(&self) -> Initializer {
match self {
Either::Left(x) => x.initializer(),
Either::Right(x) => x.initializer(),
}
}

fn poll_read(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut [u8],
) -> Poll<Result<usize>> {
unsafe {
match self.get_unchecked_mut() {
Either::Left(x) => Pin::new_unchecked(x).poll_read(cx, buf),
Either::Right(x) => Pin::new_unchecked(x).poll_read(cx, buf),
}
}
}

fn poll_read_vectored(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
bufs: &mut [IoSliceMut<'_>],
) -> Poll<Result<usize>> {
unsafe {
match self.get_unchecked_mut() {
Either::Left(x) => Pin::new_unchecked(x).poll_read_vectored(cx, bufs),
Either::Right(x) => Pin::new_unchecked(x).poll_read_vectored(cx, bufs),
}
}
}
}

impl<A, B> AsyncWrite for Either<A, B>
where
A: AsyncWrite,
B: AsyncWrite,
{
fn poll_write(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &[u8],
) -> Poll<Result<usize>> {
unsafe {
match self.get_unchecked_mut() {
Either::Left(x) => Pin::new_unchecked(x).poll_write(cx, buf),
Either::Right(x) => Pin::new_unchecked(x).poll_write(cx, buf),
}
}
}

fn poll_write_vectored(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
bufs: &[IoSlice<'_>],
) -> Poll<Result<usize>> {
unsafe {
match self.get_unchecked_mut() {
Either::Left(x) => Pin::new_unchecked(x).poll_write_vectored(cx, bufs),
Either::Right(x) => Pin::new_unchecked(x).poll_write_vectored(cx, bufs),
}
}
}

fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>> {
unsafe {
match self.get_unchecked_mut() {
Either::Left(x) => Pin::new_unchecked(x).poll_flush(cx),
Either::Right(x) => Pin::new_unchecked(x).poll_flush(cx),
}
}
}

fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>> {
unsafe {
match self.get_unchecked_mut() {
Either::Left(x) => Pin::new_unchecked(x).poll_close(cx),
Either::Right(x) => Pin::new_unchecked(x).poll_close(cx),
}
}
}
}

impl<A, B> AsyncSeek for Either<A, B>
where
A: AsyncSeek,
B: AsyncSeek,
{
fn poll_seek(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
pos: SeekFrom,
) -> Poll<Result<u64>> {
unsafe {
match self.get_unchecked_mut() {
Either::Left(x) => Pin::new_unchecked(x).poll_seek(cx, pos),
Either::Right(x) => Pin::new_unchecked(x).poll_seek(cx, pos),
}
}
}
}

impl<A, B> AsyncBufRead for Either<A, B>
where
A: AsyncBufRead,
B: AsyncBufRead,
{
fn poll_fill_buf<'a>(
self: Pin<&'a mut Self>,
cx: &mut Context<'_>,
) -> Poll<Result<&'a [u8]>> {
unsafe {
match self.get_unchecked_mut() {
Either::Left(x) => Pin::new_unchecked(x).poll_fill_buf(cx),
Either::Right(x) => Pin::new_unchecked(x).poll_fill_buf(cx),
}
}
}

fn consume(self: Pin<&mut Self>, amt: usize) {
unsafe {
match self.get_unchecked_mut() {
Either::Left(x) => Pin::new_unchecked(x).consume(amt),
Either::Right(x) => Pin::new_unchecked(x).consume(amt),
}
}
}
}
}