From 36d22d82aa202bb199967e9512281e9a53db42c9 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 21:33:14 +0200 Subject: Adding upstream version 115.7.0esr. Signed-off-by: Daniel Baumann --- third_party/rust/futures-util/src/future/either.rs | 317 +++++++++++++++++++++ 1 file changed, 317 insertions(+) create mode 100644 third_party/rust/futures-util/src/future/either.rs (limited to 'third_party/rust/futures-util/src/future/either.rs') diff --git a/third_party/rust/futures-util/src/future/either.rs b/third_party/rust/futures-util/src/future/either.rs new file mode 100644 index 0000000000..27e5064dfb --- /dev/null +++ b/third_party/rust/futures-util/src/future/either.rs @@ -0,0 +1,317 @@ +use core::pin::Pin; +use core::task::{Context, Poll}; +use futures_core::future::{FusedFuture, Future}; +use futures_core::stream::{FusedStream, Stream}; +#[cfg(feature = "sink")] +use futures_sink::Sink; + +/// Combines two different futures, streams, or sinks having the same associated types into a single type. +/// +/// This is useful when conditionally choosing between two distinct future types: +/// +/// ```rust +/// use futures::future::Either; +/// +/// # futures::executor::block_on(async { +/// let cond = true; +/// +/// let fut = if cond { +/// Either::Left(async move { 12 }) +/// } else { +/// Either::Right(async move { 44 }) +/// }; +/// +/// assert_eq!(fut.await, 12); +/// # }) +/// ``` +#[derive(Debug, Clone)] +pub enum Either { + /// First branch of the type + Left(/* #[pin] */ A), + /// Second branch of the type + Right(/* #[pin] */ B), +} + +impl Either { + /// Convert `Pin<&Either>` to `Either, Pin<&B>>`, + /// pinned projections of the inner variants. + pub fn as_pin_ref(self: Pin<&Self>) -> Either, Pin<&B>> { + // SAFETY: We can use `new_unchecked` because the `inner` parts are + // guaranteed to be pinned, as they come from `self` which is pinned. + unsafe { + match *Pin::get_ref(self) { + Either::Left(ref inner) => Either::Left(Pin::new_unchecked(inner)), + Either::Right(ref inner) => Either::Right(Pin::new_unchecked(inner)), + } + } + } + + /// Convert `Pin<&mut Either>` to `Either, Pin<&mut B>>`, + /// pinned projections of the inner variants. + pub fn as_pin_mut(self: Pin<&mut Self>) -> Either, Pin<&mut B>> { + // SAFETY: `get_unchecked_mut` is fine because we don't move anything. + // We can use `new_unchecked` because the `inner` parts are guaranteed + // to be pinned, as they come from `self` which is pinned, and we never + // offer an unpinned `&mut A` or `&mut B` through `Pin<&mut Self>`. We + // also don't have an implementation of `Drop`, nor manual `Unpin`. + unsafe { + match *Pin::get_unchecked_mut(self) { + Either::Left(ref mut inner) => Either::Left(Pin::new_unchecked(inner)), + Either::Right(ref mut inner) => Either::Right(Pin::new_unchecked(inner)), + } + } + } +} + +impl Either<(T, A), (T, B)> { + /// Factor out a homogeneous type from an either of pairs. + /// + /// Here, the homogeneous type is the first element of the pairs. + pub fn factor_first(self) -> (T, Either) { + match self { + Either::Left((x, a)) => (x, Either::Left(a)), + Either::Right((x, b)) => (x, Either::Right(b)), + } + } +} + +impl Either<(A, T), (B, T)> { + /// Factor out a homogeneous type from an either of pairs. + /// + /// Here, the homogeneous type is the second element of the pairs. + pub fn factor_second(self) -> (Either, T) { + match self { + Either::Left((a, x)) => (Either::Left(a), x), + Either::Right((b, x)) => (Either::Right(b), x), + } + } +} + +impl Either { + /// Extract the value of an either over two equivalent types. + pub fn into_inner(self) -> T { + match self { + Either::Left(x) => x, + Either::Right(x) => x, + } + } +} + +impl Future for Either +where + A: Future, + B: Future, +{ + type Output = A::Output; + + fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll { + match self.as_pin_mut() { + Either::Left(x) => x.poll(cx), + Either::Right(x) => x.poll(cx), + } + } +} + +impl FusedFuture for Either +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 Stream for Either +where + A: Stream, + B: Stream, +{ + type Item = A::Item; + + fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll> { + match self.as_pin_mut() { + Either::Left(x) => x.poll_next(cx), + Either::Right(x) => x.poll_next(cx), + } + } + + fn size_hint(&self) -> (usize, Option) { + match self { + Either::Left(x) => x.size_hint(), + Either::Right(x) => x.size_hint(), + } + } +} + +impl FusedStream for Either +where + A: FusedStream, + B: FusedStream, +{ + fn is_terminated(&self) -> bool { + match self { + Either::Left(x) => x.is_terminated(), + Either::Right(x) => x.is_terminated(), + } + } +} + +#[cfg(feature = "sink")] +impl Sink for Either +where + A: Sink, + B: Sink, +{ + type Error = A::Error; + + fn poll_ready(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll> { + match self.as_pin_mut() { + Either::Left(x) => x.poll_ready(cx), + Either::Right(x) => x.poll_ready(cx), + } + } + + fn start_send(self: Pin<&mut Self>, item: Item) -> Result<(), Self::Error> { + match self.as_pin_mut() { + Either::Left(x) => x.start_send(item), + Either::Right(x) => x.start_send(item), + } + } + + fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll> { + match self.as_pin_mut() { + Either::Left(x) => x.poll_flush(cx), + Either::Right(x) => x.poll_flush(cx), + } + } + + fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll> { + match self.as_pin_mut() { + Either::Left(x) => x.poll_close(cx), + Either::Right(x) => x.poll_close(cx), + } + } +} + +#[cfg(feature = "io")] +#[cfg(feature = "std")] +mod if_std { + use super::*; + + use core::pin::Pin; + use core::task::{Context, Poll}; + use futures_io::{ + AsyncBufRead, AsyncRead, AsyncSeek, AsyncWrite, IoSlice, IoSliceMut, Result, SeekFrom, + }; + + impl AsyncRead for Either + where + A: AsyncRead, + B: AsyncRead, + { + fn poll_read( + self: Pin<&mut Self>, + cx: &mut Context<'_>, + buf: &mut [u8], + ) -> Poll> { + match self.as_pin_mut() { + Either::Left(x) => x.poll_read(cx, buf), + Either::Right(x) => x.poll_read(cx, buf), + } + } + + fn poll_read_vectored( + self: Pin<&mut Self>, + cx: &mut Context<'_>, + bufs: &mut [IoSliceMut<'_>], + ) -> Poll> { + match self.as_pin_mut() { + Either::Left(x) => x.poll_read_vectored(cx, bufs), + Either::Right(x) => x.poll_read_vectored(cx, bufs), + } + } + } + + impl AsyncWrite for Either + where + A: AsyncWrite, + B: AsyncWrite, + { + fn poll_write( + self: Pin<&mut Self>, + cx: &mut Context<'_>, + buf: &[u8], + ) -> Poll> { + match self.as_pin_mut() { + Either::Left(x) => x.poll_write(cx, buf), + Either::Right(x) => x.poll_write(cx, buf), + } + } + + fn poll_write_vectored( + self: Pin<&mut Self>, + cx: &mut Context<'_>, + bufs: &[IoSlice<'_>], + ) -> Poll> { + match self.as_pin_mut() { + Either::Left(x) => x.poll_write_vectored(cx, bufs), + Either::Right(x) => x.poll_write_vectored(cx, bufs), + } + } + + fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll> { + match self.as_pin_mut() { + Either::Left(x) => x.poll_flush(cx), + Either::Right(x) => x.poll_flush(cx), + } + } + + fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll> { + match self.as_pin_mut() { + Either::Left(x) => x.poll_close(cx), + Either::Right(x) => x.poll_close(cx), + } + } + } + + impl AsyncSeek for Either + where + A: AsyncSeek, + B: AsyncSeek, + { + fn poll_seek( + self: Pin<&mut Self>, + cx: &mut Context<'_>, + pos: SeekFrom, + ) -> Poll> { + match self.as_pin_mut() { + Either::Left(x) => x.poll_seek(cx, pos), + Either::Right(x) => x.poll_seek(cx, pos), + } + } + } + + impl AsyncBufRead for Either + where + A: AsyncBufRead, + B: AsyncBufRead, + { + fn poll_fill_buf(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll> { + match self.as_pin_mut() { + Either::Left(x) => x.poll_fill_buf(cx), + Either::Right(x) => x.poll_fill_buf(cx), + } + } + + fn consume(self: Pin<&mut Self>, amt: usize) { + match self.as_pin_mut() { + Either::Left(x) => x.consume(amt), + Either::Right(x) => x.consume(amt), + } + } + } +} -- cgit v1.2.3