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#![allow(clippy::upper_case_acronyms)]
use super::*;
use std::convert::TryFrom;
#[repr(transparent)]
#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub struct CharULE([u8; 4]);
impl ULE for CharULE {
type Error = std::char::CharTryFromError;
#[inline]
fn parse_byte_slice(bytes: &[u8]) -> Result<&[Self], Self::Error> {
for chunk in bytes.chunks_exact(4) {
let u = u32::from_le_bytes([chunk[0], chunk[1], chunk[2], chunk[3]]);
char::try_from(u)?;
}
let data = bytes.as_ptr();
let len = bytes.len() / 4;
Ok(unsafe { std::slice::from_raw_parts(data as *const Self, len) })
}
#[inline]
fn as_byte_slice(slice: &[Self]) -> &[u8] {
let data = slice.as_ptr();
let len = slice.len() * 4;
unsafe { std::slice::from_raw_parts(data as *const u8, len) }
}
}
impl AsULE for char {
type ULE = CharULE;
#[inline]
fn as_unaligned(&self) -> Self::ULE {
let u = u32::from(*self);
CharULE(u.to_le_bytes())
}
#[inline]
fn from_unaligned(unaligned: &Self::ULE) -> Self {
let u = u32::from_le_bytes(unaligned.0);
Self::try_from(u).unwrap()
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_parse() {
let chars = ['w', 'ω', '文', '𑄃'];
let char_ules: Vec<CharULE> = chars.iter().map(char::as_unaligned).collect();
let char_bytes: &[u8] = CharULE::as_byte_slice(&char_ules);
let parsed_ules: &[CharULE] = CharULE::parse_byte_slice(&char_bytes).unwrap();
assert_eq!(char_ules, parsed_ules);
let parsed_chars: Vec<char> = parsed_ules.iter().map(char::from_unaligned).collect();
assert_eq!(&chars, parsed_chars.as_slice());
let u32s: Vec<u32> = chars.iter().copied().map(u32::from).collect();
let u32_ules: Vec<PlainOldULE<4>> = u32s.iter().map(<u32 as AsULE>::as_unaligned).collect();
let u32_bytes: &[u8] = PlainOldULE::<4>::as_byte_slice(&u32_ules);
assert_eq!(char_bytes, u32_bytes);
assert_eq!(
&[119, 0, 0, 0, 201, 3, 0, 0, 135, 101, 0, 0, 3, 17, 1, 0],
char_bytes
);
}
#[test]
fn test_failures() {
let u32s = [119, 0xD800, 120];
let u32_ules: Vec<PlainOldULE<4>> = u32s.iter().map(<u32 as AsULE>::as_unaligned).collect();
let u32_bytes: &[u8] = PlainOldULE::<4>::as_byte_slice(&u32_ules);
let parsed_ules_result = CharULE::parse_byte_slice(&u32_bytes);
assert!(matches!(parsed_ules_result, Err(_)));
let u32s = [0x20FFFF];
let u32_ules: Vec<PlainOldULE<4>> = u32s.iter().map(<u32 as AsULE>::as_unaligned).collect();
let u32_bytes: &[u8] = PlainOldULE::<4>::as_byte_slice(&u32_ules);
let parsed_ules_result = CharULE::parse_byte_slice(&u32_bytes);
assert!(matches!(parsed_ules_result, Err(_)));
}
}