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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
#![allow(clippy::upper_case_acronyms)]
//! ULE implementation for Plain Old Data types, including all sized integers.
use super::*;
use crate::impl_ule_from_array;
use crate::ZeroSlice;
use core::num::{NonZeroI8, NonZeroU8};
/// A u8 array of little-endian data with infallible conversions to and from &[u8].
#[repr(transparent)]
#[derive(Debug, PartialEq, Eq, Clone, Copy, PartialOrd, Ord, Hash)]
#[allow(clippy::exhaustive_structs)] // newtype
pub struct RawBytesULE<const N: usize>(pub [u8; N]);
impl<const N: usize> RawBytesULE<N> {
#[inline]
pub fn as_bytes(&self) -> &[u8] {
&self.0
}
#[inline]
pub fn from_byte_slice_unchecked_mut(bytes: &mut [u8]) -> &mut [Self] {
let data = bytes.as_mut_ptr();
let len = bytes.len() / N;
// Safe because Self is transparent over [u8; N]
unsafe { core::slice::from_raw_parts_mut(data as *mut Self, len) }
}
}
// 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<const N: usize> ULE for RawBytesULE<N> {
#[inline]
fn validate_byte_slice(bytes: &[u8]) -> Result<(), ZeroVecError> {
if bytes.len() % N == 0 {
// Safe because Self is transparent over [u8; N]
Ok(())
} else {
Err(ZeroVecError::length::<Self>(bytes.len()))
}
}
}
impl<const N: usize> From<[u8; N]> for RawBytesULE<N> {
#[inline]
fn from(le_bytes: [u8; N]) -> Self {
Self(le_bytes)
}
}
macro_rules! impl_byte_slice_size {
($unsigned:ty, $size:literal) => {
impl RawBytesULE<$size> {
#[doc = concat!("Gets this `RawBytesULE` as a `", stringify!($unsigned), "`. This is equivalent to calling [`AsULE::from_unaligned()`] on the appropriately sized type.")]
#[inline]
pub fn as_unsigned_int(&self) -> $unsigned {
<$unsigned as $crate::ule::AsULE>::from_unaligned(*self)
}
#[doc = concat!("Converts a `", stringify!($unsigned), "` to a `RawBytesULE`. This is equivalent to calling [`AsULE::to_unaligned()`] on the appropriately sized type.")]
#[inline]
pub const fn from_aligned(value: $unsigned) -> Self {
Self(value.to_le_bytes())
}
impl_ule_from_array!(
$unsigned,
RawBytesULE<$size>,
RawBytesULE([0; $size])
);
}
};
}
macro_rules! impl_const_constructors {
($base:ty, $size:literal) => {
impl ZeroSlice<$base> {
/// This function can be used for constructing ZeroVecs in a const context, avoiding
/// parsing checks.
///
/// This cannot be generic over T because of current limitations in `const`, but if
/// this method is needed in a non-const context, check out [`ZeroSlice::parse_byte_slice()`]
/// instead.
///
/// See [`ZeroSlice::cast()`] for an example.
pub const fn try_from_bytes(bytes: &[u8]) -> Result<&Self, ZeroVecError> {
let len = bytes.len();
#[allow(clippy::modulo_one)]
if len % $size == 0 {
Ok(unsafe { Self::from_bytes_unchecked(bytes) })
} else {
Err(ZeroVecError::InvalidLength {
ty: concat!("<const construct: ", $size, ">"),
len,
})
}
}
}
};
}
macro_rules! impl_byte_slice_type {
($single_fn:ident, $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 to_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 $type {}
impl RawBytesULE<$size> {
pub const fn $single_fn(v: $type) -> Self {
RawBytesULE(v.to_le_bytes())
}
}
};
}
macro_rules! impl_byte_slice_unsigned_type {
($type:ty, $size:literal) => {
impl_byte_slice_type!(from_unsigned, $type, $size);
};
}
macro_rules! impl_byte_slice_signed_type {
($type:ty, $size:literal) => {
impl_byte_slice_type!(from_signed, $type, $size);
};
}
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_unsigned_type!(u16, 2);
impl_byte_slice_unsigned_type!(u32, 4);
impl_byte_slice_unsigned_type!(u64, 8);
impl_byte_slice_unsigned_type!(u128, 16);
impl_byte_slice_signed_type!(i16, 2);
impl_byte_slice_signed_type!(i32, 4);
impl_byte_slice_signed_type!(i64, 8);
impl_byte_slice_signed_type!(i128, 16);
impl_const_constructors!(u8, 1);
impl_const_constructors!(u16, 2);
impl_const_constructors!(u32, 4);
impl_const_constructors!(u64, 8);
impl_const_constructors!(u128, 16);
// Note: The f32 and f64 const constructors currently have limited use because
// `f32::to_le_bytes` is not yet const.
impl_const_constructors!(bool, 1);
// 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 to_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. NonZeroU8 does not include any uninitialized or padding bytes.
// 2. NonZeroU8 is aligned to 1 byte.
// 3. The impl of validate_byte_slice() returns an error if any byte is not valid (0x00).
// 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. NonZeroU8 byte equality is semantic equality
unsafe impl ULE for NonZeroU8 {
#[inline]
fn validate_byte_slice(bytes: &[u8]) -> Result<(), ZeroVecError> {
bytes.iter().try_for_each(|b| {
if *b == 0x00 {
Err(ZeroVecError::parse::<Self>())
} else {
Ok(())
}
})
}
}
impl AsULE for NonZeroU8 {
type ULE = Self;
#[inline]
fn to_unaligned(self) -> Self::ULE {
self
}
#[inline]
fn from_unaligned(unaligned: Self::ULE) -> Self {
unaligned
}
}
unsafe impl EqULE for NonZeroU8 {}
impl NicheBytes<1> for NonZeroU8 {
const NICHE_BIT_PATTERN: [u8; 1] = [0x00];
}
// 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 to_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 {}
impl AsULE for NonZeroI8 {
type ULE = NonZeroU8;
#[inline]
fn to_unaligned(self) -> Self::ULE {
// Safety: NonZeroU8 and NonZeroI8 have same size
unsafe { core::mem::transmute(self) }
}
#[inline]
fn from_unaligned(unaligned: Self::ULE) -> Self {
// Safety: NonZeroU8 and NonZeroI8 have same size
unsafe { core::mem::transmute(unaligned) }
}
}
// These impls are actually safe and portable due to Rust always using IEEE 754, see the documentation
//
// The only potential problem is that some older platforms treat signaling NaNs differently. This is
// still quite portable, signalingness is not typically super important.
impl AsULE for f32 {
type ULE = RawBytesULE<4>;
#[inline]
fn to_unaligned(self) -> Self::ULE {
self.to_bits().to_unaligned()
}
#[inline]
fn from_unaligned(unaligned: Self::ULE) -> Self {
Self::from_bits(u32::from_unaligned(unaligned))
}
}
impl AsULE for f64 {
type ULE = RawBytesULE<8>;
#[inline]
fn to_unaligned(self) -> Self::ULE {
self.to_bits().to_unaligned()
}
#[inline]
fn from_unaligned(unaligned: Self::ULE) -> Self {
Self::from_bits(u64::from_unaligned(unaligned))
}
}
// The from_bits documentation mentions that they have identical byte representations to integers
// and EqULE only cares about LE systems
unsafe impl EqULE for f32 {}
unsafe impl EqULE for f64 {}
// The bool impl is not as efficient as it could be
// We can, in the future, have https://github.com/unicode-org/icu4x/blob/main/utils/zerovec/design_doc.md#bitpacking
// for better bitpacking
// Safety (based on the safety checklist on the ULE trait):
// 1. bool does not include any uninitialized or padding bytes (the remaining 7 bytes in bool are by definition zero)
// 2. bool is aligned to 1 byte.
// 3. The impl of validate_byte_slice() returns an error if any byte is not valid (bytes that are not 0 or 1).
// 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. bool byte equality is semantic equality
unsafe impl ULE for bool {
#[inline]
fn validate_byte_slice(bytes: &[u8]) -> Result<(), ZeroVecError> {
for byte in bytes {
// Rust booleans are always size 1, align 1 values with valid bit patterns 0x0 or 0x1
if *byte > 1 {
return Err(ZeroVecError::parse::<Self>());
}
}
Ok(())
}
}
impl AsULE for bool {
type ULE = Self;
#[inline]
fn to_unaligned(self) -> Self::ULE {
self
}
#[inline]
fn from_unaligned(unaligned: Self::ULE) -> Self {
unaligned
}
}
// EqULE is true because bool is its own ULE.
unsafe impl EqULE for bool {}