| 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) |
| } |
| } |
| } |