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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:03:36 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:03:36 +0000 |
commit | 17d40c6057c88f4c432b0d7bac88e1b84cb7e67f (patch) | |
tree | 3f66c4a5918660bb8a758ab6cda5ff8ee4f6cdcd /library/std/src/net/display_buffer.rs | |
parent | Adding upstream version 1.64.0+dfsg1. (diff) | |
download | rustc-f7f0cc2a5d72e2c61c1f6900e70eec992bea4273.tar.xz rustc-f7f0cc2a5d72e2c61c1f6900e70eec992bea4273.zip |
Adding upstream version 1.65.0+dfsg1.upstream/1.65.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'library/std/src/net/display_buffer.rs')
-rw-r--r-- | library/std/src/net/display_buffer.rs | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/library/std/src/net/display_buffer.rs b/library/std/src/net/display_buffer.rs new file mode 100644 index 000000000..7aadf06e9 --- /dev/null +++ b/library/std/src/net/display_buffer.rs @@ -0,0 +1,40 @@ +use crate::fmt; +use crate::mem::MaybeUninit; +use crate::str; + +/// Used for slow path in `Display` implementations when alignment is required. +pub struct DisplayBuffer<const SIZE: usize> { + buf: [MaybeUninit<u8>; SIZE], + len: usize, +} + +impl<const SIZE: usize> DisplayBuffer<SIZE> { + #[inline] + pub const fn new() -> Self { + Self { buf: MaybeUninit::uninit_array(), len: 0 } + } + + #[inline] + pub fn as_str(&self) -> &str { + // SAFETY: `buf` is only written to by the `fmt::Write::write_str` implementation + // which writes a valid UTF-8 string to `buf` and correctly sets `len`. + unsafe { + let s = MaybeUninit::slice_assume_init_ref(&self.buf[..self.len]); + str::from_utf8_unchecked(s) + } + } +} + +impl<const SIZE: usize> fmt::Write for DisplayBuffer<SIZE> { + fn write_str(&mut self, s: &str) -> fmt::Result { + let bytes = s.as_bytes(); + + if let Some(buf) = self.buf.get_mut(self.len..(self.len + bytes.len())) { + MaybeUninit::write_slice(buf, bytes); + self.len += bytes.len(); + Ok(()) + } else { + Err(fmt::Error) + } + } +} |