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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
commit | 698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch) | |
tree | 173a775858bd501c378080a10dca74132f05bc50 /vendor/futures-util/src/io/empty.rs | |
parent | Initial commit. (diff) | |
download | rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip |
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'vendor/futures-util/src/io/empty.rs')
-rw-r--r-- | vendor/futures-util/src/io/empty.rs | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/vendor/futures-util/src/io/empty.rs b/vendor/futures-util/src/io/empty.rs new file mode 100644 index 000000000..02f6103f5 --- /dev/null +++ b/vendor/futures-util/src/io/empty.rs @@ -0,0 +1,59 @@ +use futures_core::task::{Context, Poll}; +use futures_io::{AsyncBufRead, AsyncRead}; +use std::fmt; +use std::io; +use std::pin::Pin; + +/// Reader for the [`empty()`] function. +#[must_use = "readers do nothing unless polled"] +pub struct Empty { + _priv: (), +} + +/// Constructs a new handle to an empty reader. +/// +/// All reads from the returned reader will return `Poll::Ready(Ok(0))`. +/// +/// # Examples +/// +/// A slightly sad example of not reading anything into a buffer: +/// +/// ``` +/// # futures::executor::block_on(async { +/// use futures::io::{self, AsyncReadExt}; +/// +/// let mut buffer = String::new(); +/// let mut reader = io::empty(); +/// reader.read_to_string(&mut buffer).await?; +/// assert!(buffer.is_empty()); +/// # Ok::<(), Box<dyn std::error::Error>>(()) }).unwrap(); +/// ``` +pub fn empty() -> Empty { + Empty { _priv: () } +} + +impl AsyncRead for Empty { + #[inline] + fn poll_read( + self: Pin<&mut Self>, + _: &mut Context<'_>, + _: &mut [u8], + ) -> Poll<io::Result<usize>> { + Poll::Ready(Ok(0)) + } +} + +impl AsyncBufRead for Empty { + #[inline] + fn poll_fill_buf(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<io::Result<&[u8]>> { + Poll::Ready(Ok(&[])) + } + #[inline] + fn consume(self: Pin<&mut Self>, _: usize) {} +} + +impl fmt::Debug for Empty { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.pad("Empty { .. }") + } +} |