1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366
// 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::*;
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
// on f32::from_bits: https://doc.rust-lang.org/stable/std/primitive.f32.html#method.from_bits
//
// 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 {
// https://doc.rust-lang.org/reference/types/boolean.html
// 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 {}