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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 19:33:14 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 19:33:14 +0000 |
commit | 36d22d82aa202bb199967e9512281e9a53db42c9 (patch) | |
tree | 105e8c98ddea1c1e4784a60a5a6410fa416be2de /third_party/rust/tokio-stream/src/pending.rs | |
parent | Initial commit. (diff) | |
download | firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.tar.xz firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.zip |
Adding upstream version 115.7.0esr.upstream/115.7.0esr
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'third_party/rust/tokio-stream/src/pending.rs')
-rw-r--r-- | third_party/rust/tokio-stream/src/pending.rs | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/third_party/rust/tokio-stream/src/pending.rs b/third_party/rust/tokio-stream/src/pending.rs new file mode 100644 index 0000000000..b50fd33354 --- /dev/null +++ b/third_party/rust/tokio-stream/src/pending.rs @@ -0,0 +1,54 @@ +use crate::Stream; + +use core::marker::PhantomData; +use core::pin::Pin; +use core::task::{Context, Poll}; + +/// Stream for the [`pending`](fn@pending) function. +#[derive(Debug)] +#[must_use = "streams do nothing unless polled"] +pub struct Pending<T>(PhantomData<T>); + +impl<T> Unpin for Pending<T> {} +unsafe impl<T> Send for Pending<T> {} +unsafe impl<T> Sync for Pending<T> {} + +/// Creates a stream that is never ready +/// +/// The returned stream is never ready. Attempting to call +/// [`next()`](crate::StreamExt::next) will never complete. Use +/// [`stream::empty()`](super::empty()) to obtain a stream that is is +/// immediately empty but returns no values. +/// +/// # Examples +/// +/// Basic usage: +/// +/// ```no_run +/// use tokio_stream::{self as stream, StreamExt}; +/// +/// #[tokio::main] +/// async fn main() { +/// let mut never = stream::pending::<i32>(); +/// +/// // This will never complete +/// never.next().await; +/// +/// unreachable!(); +/// } +/// ``` +pub const fn pending<T>() -> Pending<T> { + Pending(PhantomData) +} + +impl<T> Stream for Pending<T> { + type Item = T; + + fn poll_next(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Option<T>> { + Poll::Pending + } + + fn size_hint(&self) -> (usize, Option<usize>) { + (0, None) + } +} |