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// This file is part of ICU4X. For terms of use, please see the file
// called LICENSE at the top level of the ICU4X source tree
// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
#![allow(clippy::upper_case_acronyms)]
//! ULE implementation for Plain Old Data types, including all sized integers.
use super::*;
/// A u8 array of little-endian data with infallible conversions to and from &[u8].
#[repr(transparent)]
#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub struct RawBytesULE<const N: usize>(pub [u8; N]);
macro_rules! impl_byte_slice_size {
($unsigned:ty, $size:literal) => {
impl From<[u8; $size]> for RawBytesULE<$size> {
#[inline]
fn from(le_bytes: [u8; $size]) -> Self {
Self(le_bytes)
}
}
impl RawBytesULE<$size> {
#[inline]
pub fn as_bytes(&self) -> &[u8] {
&self.0
}
}
// Safety (based on the safety checklist on the ULE trait):
// 1. RawBytesULE does not include any uninitialized or padding bytes.
// (achieved by `#[repr(transparent)]` on a type that satisfies this invariant)
// 2. RawBytesULE is aligned to 1 byte.
// (achieved by `#[repr(transparent)]` on a type that satisfies this invariant)
// 3. The impl of validate_byte_slice() returns an error if any byte is not valid (never).
// 4. The impl of validate_byte_slice() returns an error if there are leftover bytes.
// 5. The other ULE methods use the default impl.
// 6. RawBytesULE byte equality is semantic equality
unsafe impl ULE for RawBytesULE<$size> {
#[inline]
fn validate_byte_slice(bytes: &[u8]) -> Result<(), ZeroVecError> {
if bytes.len() % $size == 0 {
// Safe because Self is transparent over [u8; $size]
Ok(())
} else {
Err(ZeroVecError::length::<Self>(bytes.len()))
}
}
}
impl RawBytesULE<$size> {
#[inline]
pub fn from_byte_slice_unchecked_mut(bytes: &mut [u8]) -> &mut [Self] {
let data = bytes.as_mut_ptr();
let len = bytes.len() / $size;
// Safe because Self is transparent over [u8; $size]
unsafe { core::slice::from_raw_parts_mut(data as *mut Self, len) }
}
/// Gets this RawBytesULE as an unsigned int. This is equivalent to calling
/// [AsULE::from_unaligned()] on the appropriately sized type.
#[inline]
pub fn as_unsigned_int(&self) -> $unsigned {
<$unsigned as $crate::ule::AsULE>::from_unaligned(*self)
}
}
};
}
macro_rules! impl_byte_slice_type {
($type:ty, $size:literal) => {
impl From<$type> for RawBytesULE<$size> {
#[inline]
fn from(value: $type) -> Self {
Self(value.to_le_bytes())
}
}
impl AsULE for $type {
type ULE = RawBytesULE<$size>;
#[inline]
fn as_unaligned(self) -> Self::ULE {
RawBytesULE(self.to_le_bytes())
}
#[inline]
fn from_unaligned(unaligned: Self::ULE) -> Self {
<$type>::from_le_bytes(unaligned.0)
}
}
// EqULE is true because $type and RawBytesULE<$size>
// have the same byte sequence on little-endian
unsafe impl EqULE for $type {}
};
}
impl_byte_slice_size!(u16, 2);
impl_byte_slice_size!(u32, 4);
impl_byte_slice_size!(u64, 8);
impl_byte_slice_size!(u128, 16);
impl_byte_slice_type!(u16, 2);
impl_byte_slice_type!(u32, 4);
impl_byte_slice_type!(u64, 8);
impl_byte_slice_type!(u128, 16);
impl_byte_slice_type!(i16, 2);
impl_byte_slice_type!(i32, 4);
impl_byte_slice_type!(i64, 8);
impl_byte_slice_type!(i128, 16);
// Safety (based on the safety checklist on the ULE trait):
// 1. u8 does not include any uninitialized or padding bytes.
// 2. u8 is aligned to 1 byte.
// 3. The impl of validate_byte_slice() returns an error if any byte is not valid (never).
// 4. The impl of validate_byte_slice() returns an error if there are leftover bytes (never).
// 5. The other ULE methods use the default impl.
// 6. u8 byte equality is semantic equality
unsafe impl ULE for u8 {
#[inline]
fn validate_byte_slice(_bytes: &[u8]) -> Result<(), ZeroVecError> {
Ok(())
}
}
impl AsULE for u8 {
type ULE = Self;
#[inline]
fn as_unaligned(self) -> Self::ULE {
self
}
#[inline]
fn from_unaligned(unaligned: Self::ULE) -> Self {
unaligned
}
}
// EqULE is true because u8 is its own ULE.
unsafe impl EqULE for u8 {}
// Safety (based on the safety checklist on the ULE trait):
// 1. i8 does not include any uninitialized or padding bytes.
// 2. i8 is aligned to 1 byte.
// 3. The impl of validate_byte_slice() returns an error if any byte is not valid (never).
// 4. The impl of validate_byte_slice() returns an error if there are leftover bytes (never).
// 5. The other ULE methods use the default impl.
// 6. i8 byte equality is semantic equality
unsafe impl ULE for i8 {
#[inline]
fn validate_byte_slice(_bytes: &[u8]) -> Result<(), ZeroVecError> {
Ok(())
}
}
impl AsULE for i8 {
type ULE = Self;
#[inline]
fn as_unaligned(self) -> Self::ULE {
self
}
#[inline]
fn from_unaligned(unaligned: Self::ULE) -> Self {
unaligned
}
}
// EqULE is true because i8 is its own ULE.
unsafe impl EqULE for i8 {}