437 lines
16 KiB
Rust
437 lines
16 KiB
Rust
// 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 ).
|
|
|
|
use crate::ule::*;
|
|
use crate::varzerovec::VarZeroVecFormat;
|
|
use crate::{VarZeroSlice, VarZeroVec, ZeroSlice, ZeroVec};
|
|
#[cfg(feature = "alloc")]
|
|
use alloc::borrow::{Cow, ToOwned};
|
|
#[cfg(feature = "alloc")]
|
|
use alloc::boxed::Box;
|
|
#[cfg(feature = "alloc")]
|
|
use alloc::string::String;
|
|
#[cfg(feature = "alloc")]
|
|
use alloc::{vec, vec::Vec};
|
|
|
|
/// Allows types to be encoded as [`VarULE`]s. This is highly useful for implementing [`VarULE`] on
|
|
/// custom DSTs where the type cannot be obtained as a reference to some other type.
|
|
///
|
|
/// [`Self::encode_var_ule_as_slices()`] should be implemented by providing an encoded slice for each field
|
|
/// of the [`VarULE`] type to the callback, in order. For an implementation to be safe, the slices
|
|
/// to the callback must, when concatenated, be a valid instance of the [`VarULE`] type.
|
|
///
|
|
/// See the [custom `VarULEdocumentation`](crate::ule::custom) for examples.
|
|
///
|
|
/// [`Self::encode_var_ule_as_slices()`] is only used to provide default implementations for [`Self::encode_var_ule_write()`]
|
|
/// and [`Self::encode_var_ule_len()`]. If you override the default implementations it is totally valid to
|
|
/// replace [`Self::encode_var_ule_as_slices()`]'s body with `unreachable!()`. This can be done for cases where
|
|
/// it is not possible to implement [`Self::encode_var_ule_as_slices()`] but the other methods still work.
|
|
///
|
|
/// A typical implementation will take each field in the order found in the [`VarULE`] type,
|
|
/// convert it to ULE, call [`ULE::slice_as_bytes()`] on them, and pass the slices to `cb` in order.
|
|
/// A trailing [`ZeroVec`](crate::ZeroVec) or [`VarZeroVec`](crate::VarZeroVec) can have their underlying
|
|
/// byte representation passed through.
|
|
///
|
|
/// In case the compiler is not optimizing [`Self::encode_var_ule_len()`], it can be overridden. A typical
|
|
/// implementation will add up the sizes of each field on the [`VarULE`] type and then add in the byte length of the
|
|
/// dynamically-sized part.
|
|
///
|
|
/// # Reverse-encoding [`VarULE`]
|
|
///
|
|
/// This trait maps a struct to its bytes representation ("serialization"), and
|
|
/// [`ZeroFrom`](zerofrom::ZeroFrom) performs the opposite operation, taking those bytes and
|
|
/// creating a struct from them ("deserialization").
|
|
///
|
|
/// # Safety
|
|
///
|
|
/// The safety invariants of [`Self::encode_var_ule_as_slices()`] are:
|
|
/// - It must call `cb` (only once)
|
|
/// - The slices passed to `cb`, if concatenated, should be a valid instance of the `T` [`VarULE`] type
|
|
/// (i.e. if fed to [`VarULE::validate_bytes()`] they must produce a successful result)
|
|
/// - It must return the return value of `cb` to the caller
|
|
///
|
|
/// One or more of [`Self::encode_var_ule_len()`] and [`Self::encode_var_ule_write()`] may be provided.
|
|
/// If both are, then `zerovec` code is guaranteed to not call [`Self::encode_var_ule_as_slices()`], and it may be replaced
|
|
/// with `unreachable!()`.
|
|
///
|
|
/// The safety invariants of [`Self::encode_var_ule_len()`] are:
|
|
/// - It must return the length of the corresponding [`VarULE`] type
|
|
///
|
|
/// The safety invariants of [`Self::encode_var_ule_write()`] are:
|
|
/// - The slice written to `dst` must be a valid instance of the `T` [`VarULE`] type
|
|
pub unsafe trait EncodeAsVarULE<T: VarULE + ?Sized> {
|
|
/// Calls `cb` with a piecewise list of byte slices that when concatenated
|
|
/// produce the memory pattern of the corresponding instance of `T`.
|
|
///
|
|
/// Do not call this function directly; instead use the other two. Some implementors
|
|
/// may define this function to panic.
|
|
fn encode_var_ule_as_slices<R>(&self, cb: impl FnOnce(&[&[u8]]) -> R) -> R;
|
|
|
|
/// Return the length, in bytes, of the corresponding [`VarULE`] type
|
|
fn encode_var_ule_len(&self) -> usize {
|
|
self.encode_var_ule_as_slices(|slices| slices.iter().map(|s| s.len()).sum())
|
|
}
|
|
|
|
/// Write the corresponding [`VarULE`] type to the `dst` buffer. `dst` should
|
|
/// be the size of [`Self::encode_var_ule_len()`]
|
|
fn encode_var_ule_write(&self, mut dst: &mut [u8]) {
|
|
debug_assert_eq!(self.encode_var_ule_len(), dst.len());
|
|
self.encode_var_ule_as_slices(move |slices| {
|
|
#[expect(clippy::indexing_slicing)] // by debug_assert
|
|
for slice in slices {
|
|
dst[..slice.len()].copy_from_slice(slice);
|
|
dst = &mut dst[slice.len()..];
|
|
}
|
|
});
|
|
}
|
|
}
|
|
|
|
/// Given an [`EncodeAsVarULE`] type `S`, encode it into a `Box<T>`
|
|
///
|
|
/// This is primarily useful for generating `Deserialize` impls for [`VarULE`] types
|
|
#[cfg(feature = "alloc")]
|
|
pub fn encode_varule_to_box<S: EncodeAsVarULE<T> + ?Sized, T: VarULE + ?Sized>(x: &S) -> Box<T> {
|
|
// zero-fill the vector to avoid uninitialized data UB
|
|
let mut vec: Vec<u8> = vec![0; x.encode_var_ule_len()];
|
|
x.encode_var_ule_write(&mut vec);
|
|
let boxed = core::mem::ManuallyDrop::new(vec.into_boxed_slice());
|
|
unsafe {
|
|
// Safety: `ptr` is a box, and `T` is a VarULE which guarantees it has the same memory layout as `[u8]`
|
|
// and can be recouped via from_bytes_unchecked()
|
|
let ptr: *mut T = T::from_bytes_unchecked(&boxed) as *const T as *mut T;
|
|
|
|
// Safety: we can construct an owned version since we have mem::forgotten the older owner
|
|
Box::from_raw(ptr)
|
|
}
|
|
}
|
|
|
|
unsafe impl<T: VarULE + ?Sized> EncodeAsVarULE<T> for T {
|
|
fn encode_var_ule_as_slices<R>(&self, cb: impl FnOnce(&[&[u8]]) -> R) -> R {
|
|
cb(&[T::as_bytes(self)])
|
|
}
|
|
}
|
|
|
|
unsafe impl<T: VarULE + ?Sized> EncodeAsVarULE<T> for &'_ T {
|
|
fn encode_var_ule_as_slices<R>(&self, cb: impl FnOnce(&[&[u8]]) -> R) -> R {
|
|
cb(&[T::as_bytes(self)])
|
|
}
|
|
}
|
|
|
|
unsafe impl<T: VarULE + ?Sized> EncodeAsVarULE<T> for &'_ &'_ T {
|
|
fn encode_var_ule_as_slices<R>(&self, cb: impl FnOnce(&[&[u8]]) -> R) -> R {
|
|
cb(&[T::as_bytes(self)])
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "alloc")]
|
|
unsafe impl<T: VarULE + ?Sized> EncodeAsVarULE<T> for Cow<'_, T>
|
|
where
|
|
T: ToOwned,
|
|
{
|
|
fn encode_var_ule_as_slices<R>(&self, cb: impl FnOnce(&[&[u8]]) -> R) -> R {
|
|
cb(&[T::as_bytes(self.as_ref())])
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "alloc")]
|
|
unsafe impl<T: VarULE + ?Sized> EncodeAsVarULE<T> for Box<T> {
|
|
fn encode_var_ule_as_slices<R>(&self, cb: impl FnOnce(&[&[u8]]) -> R) -> R {
|
|
cb(&[T::as_bytes(self)])
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "alloc")]
|
|
unsafe impl<T: VarULE + ?Sized> EncodeAsVarULE<T> for &'_ Box<T> {
|
|
fn encode_var_ule_as_slices<R>(&self, cb: impl FnOnce(&[&[u8]]) -> R) -> R {
|
|
cb(&[T::as_bytes(self)])
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "alloc")]
|
|
unsafe impl EncodeAsVarULE<str> for String {
|
|
fn encode_var_ule_as_slices<R>(&self, cb: impl FnOnce(&[&[u8]]) -> R) -> R {
|
|
cb(&[self.as_bytes()])
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "alloc")]
|
|
unsafe impl EncodeAsVarULE<str> for &'_ String {
|
|
fn encode_var_ule_as_slices<R>(&self, cb: impl FnOnce(&[&[u8]]) -> R) -> R {
|
|
cb(&[self.as_bytes()])
|
|
}
|
|
}
|
|
|
|
// Note: This impl could technically use `T: AsULE`, but we want users to prefer `ZeroSlice<T>`
|
|
// for cases where T is not a ULE. Therefore, we can use the more efficient `memcpy` impl here.
|
|
#[cfg(feature = "alloc")]
|
|
unsafe impl<T> EncodeAsVarULE<[T]> for Vec<T>
|
|
where
|
|
T: ULE,
|
|
{
|
|
fn encode_var_ule_as_slices<R>(&self, cb: impl FnOnce(&[&[u8]]) -> R) -> R {
|
|
cb(&[<[T] as VarULE>::as_bytes(self)])
|
|
}
|
|
}
|
|
|
|
unsafe impl<T> EncodeAsVarULE<ZeroSlice<T>> for &'_ [T]
|
|
where
|
|
T: AsULE + 'static,
|
|
{
|
|
fn encode_var_ule_as_slices<R>(&self, _: impl FnOnce(&[&[u8]]) -> R) -> R {
|
|
// unnecessary if the other two are implemented
|
|
unreachable!()
|
|
}
|
|
|
|
#[inline]
|
|
fn encode_var_ule_len(&self) -> usize {
|
|
self.len() * size_of::<T::ULE>()
|
|
}
|
|
|
|
fn encode_var_ule_write(&self, dst: &mut [u8]) {
|
|
#[allow(non_snake_case)]
|
|
let S = size_of::<T::ULE>();
|
|
debug_assert_eq!(self.len() * S, dst.len());
|
|
for (item, ref mut chunk) in self.iter().zip(dst.chunks_mut(S)) {
|
|
let ule = item.to_unaligned();
|
|
chunk.copy_from_slice(ULE::slice_as_bytes(slice::from_ref(&ule)));
|
|
}
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "alloc")]
|
|
unsafe impl<T> EncodeAsVarULE<ZeroSlice<T>> for Vec<T>
|
|
where
|
|
T: AsULE + 'static,
|
|
{
|
|
fn encode_var_ule_as_slices<R>(&self, _: impl FnOnce(&[&[u8]]) -> R) -> R {
|
|
// unnecessary if the other two are implemented
|
|
unreachable!()
|
|
}
|
|
|
|
#[inline]
|
|
fn encode_var_ule_len(&self) -> usize {
|
|
self.as_slice().encode_var_ule_len()
|
|
}
|
|
|
|
#[inline]
|
|
fn encode_var_ule_write(&self, dst: &mut [u8]) {
|
|
self.as_slice().encode_var_ule_write(dst)
|
|
}
|
|
}
|
|
|
|
unsafe impl<T> EncodeAsVarULE<ZeroSlice<T>> for ZeroVec<'_, T>
|
|
where
|
|
T: AsULE + 'static,
|
|
{
|
|
fn encode_var_ule_as_slices<R>(&self, _: impl FnOnce(&[&[u8]]) -> R) -> R {
|
|
// unnecessary if the other two are implemented
|
|
unreachable!()
|
|
}
|
|
|
|
#[inline]
|
|
fn encode_var_ule_len(&self) -> usize {
|
|
self.as_bytes().len()
|
|
}
|
|
|
|
fn encode_var_ule_write(&self, dst: &mut [u8]) {
|
|
debug_assert_eq!(self.as_bytes().len(), dst.len());
|
|
dst.copy_from_slice(self.as_bytes());
|
|
}
|
|
}
|
|
|
|
unsafe impl<T, E, F> EncodeAsVarULE<VarZeroSlice<T, F>> for &'_ [E]
|
|
where
|
|
T: VarULE + ?Sized,
|
|
E: EncodeAsVarULE<T>,
|
|
F: VarZeroVecFormat,
|
|
{
|
|
fn encode_var_ule_as_slices<R>(&self, _: impl FnOnce(&[&[u8]]) -> R) -> R {
|
|
// unnecessary if the other two are implemented
|
|
unimplemented!()
|
|
}
|
|
|
|
#[expect(clippy::unwrap_used)] // TODO(#1410): Rethink length errors in VZV.
|
|
fn encode_var_ule_len(&self) -> usize {
|
|
crate::varzerovec::components::compute_serializable_len::<T, E, F>(self).unwrap() as usize
|
|
}
|
|
|
|
fn encode_var_ule_write(&self, dst: &mut [u8]) {
|
|
crate::varzerovec::components::write_serializable_bytes::<T, E, F>(self, dst)
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "alloc")]
|
|
unsafe impl<T, E, F> EncodeAsVarULE<VarZeroSlice<T, F>> for Vec<E>
|
|
where
|
|
T: VarULE + ?Sized,
|
|
E: EncodeAsVarULE<T>,
|
|
F: VarZeroVecFormat,
|
|
{
|
|
fn encode_var_ule_as_slices<R>(&self, _: impl FnOnce(&[&[u8]]) -> R) -> R {
|
|
// unnecessary if the other two are implemented
|
|
unreachable!()
|
|
}
|
|
|
|
#[inline]
|
|
fn encode_var_ule_len(&self) -> usize {
|
|
<_ as EncodeAsVarULE<VarZeroSlice<T, F>>>::encode_var_ule_len(&self.as_slice())
|
|
}
|
|
|
|
#[inline]
|
|
fn encode_var_ule_write(&self, dst: &mut [u8]) {
|
|
<_ as EncodeAsVarULE<VarZeroSlice<T, F>>>::encode_var_ule_write(&self.as_slice(), dst)
|
|
}
|
|
}
|
|
|
|
unsafe impl<T, F> EncodeAsVarULE<VarZeroSlice<T, F>> for VarZeroVec<'_, T, F>
|
|
where
|
|
T: VarULE + ?Sized,
|
|
F: VarZeroVecFormat,
|
|
{
|
|
fn encode_var_ule_as_slices<R>(&self, _: impl FnOnce(&[&[u8]]) -> R) -> R {
|
|
// unnecessary if the other two are implemented
|
|
unreachable!()
|
|
}
|
|
|
|
#[inline]
|
|
fn encode_var_ule_len(&self) -> usize {
|
|
self.as_bytes().len()
|
|
}
|
|
|
|
#[inline]
|
|
fn encode_var_ule_write(&self, dst: &mut [u8]) {
|
|
debug_assert_eq!(self.as_bytes().len(), dst.len());
|
|
dst.copy_from_slice(self.as_bytes());
|
|
}
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod test {
|
|
use super::*;
|
|
|
|
const STRING_ARRAY: [&str; 2] = ["hello", "world"];
|
|
|
|
const STRING_SLICE: &[&str] = &STRING_ARRAY;
|
|
|
|
const U8_ARRAY: [u8; 8] = [0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07];
|
|
|
|
const U8_2D_ARRAY: [&[u8]; 2] = [&U8_ARRAY, &U8_ARRAY];
|
|
|
|
const U8_2D_SLICE: &[&[u8]] = &[&U8_ARRAY, &U8_ARRAY];
|
|
|
|
const U8_3D_ARRAY: [&[&[u8]]; 2] = [U8_2D_SLICE, U8_2D_SLICE];
|
|
|
|
const U8_3D_SLICE: &[&[&[u8]]] = &[U8_2D_SLICE, U8_2D_SLICE];
|
|
|
|
const U32_ARRAY: [u32; 4] = [0x00010203, 0x04050607, 0x08090A0B, 0x0C0D0E0F];
|
|
|
|
const U32_2D_ARRAY: [&[u32]; 2] = [&U32_ARRAY, &U32_ARRAY];
|
|
|
|
const U32_2D_SLICE: &[&[u32]] = &[&U32_ARRAY, &U32_ARRAY];
|
|
|
|
const U32_3D_ARRAY: [&[&[u32]]; 2] = [U32_2D_SLICE, U32_2D_SLICE];
|
|
|
|
const U32_3D_SLICE: &[&[&[u32]]] = &[U32_2D_SLICE, U32_2D_SLICE];
|
|
|
|
#[test]
|
|
fn test_vzv_from() {
|
|
type VZV<'a, T> = VarZeroVec<'a, T>;
|
|
type ZS<T> = ZeroSlice<T>;
|
|
type VZS<T> = VarZeroSlice<T>;
|
|
|
|
let u8_zerovec: ZeroVec<u8> = ZeroVec::from_slice_or_alloc(&U8_ARRAY);
|
|
let u8_2d_zerovec: [ZeroVec<u8>; 2] = [u8_zerovec.clone(), u8_zerovec.clone()];
|
|
let u8_2d_vec: Vec<Vec<u8>> = vec![U8_ARRAY.into(), U8_ARRAY.into()];
|
|
let u8_3d_vec: Vec<Vec<Vec<u8>>> = vec![u8_2d_vec.clone(), u8_2d_vec.clone()];
|
|
|
|
let u32_zerovec: ZeroVec<u32> = ZeroVec::from_slice_or_alloc(&U32_ARRAY);
|
|
let u32_2d_zerovec: [ZeroVec<u32>; 2] = [u32_zerovec.clone(), u32_zerovec.clone()];
|
|
let u32_2d_vec: Vec<Vec<u32>> = vec![U32_ARRAY.into(), U32_ARRAY.into()];
|
|
let u32_3d_vec: Vec<Vec<Vec<u32>>> = vec![u32_2d_vec.clone(), u32_2d_vec.clone()];
|
|
|
|
let a: VZV<str> = VarZeroVec::from(&STRING_ARRAY);
|
|
let b: VZV<str> = VarZeroVec::from(STRING_SLICE);
|
|
let c: VZV<str> = VarZeroVec::from(&Vec::from(STRING_SLICE));
|
|
assert_eq!(a, STRING_SLICE);
|
|
assert_eq!(a, b);
|
|
assert_eq!(a, c);
|
|
|
|
let a: VZV<[u8]> = VarZeroVec::from(&U8_2D_ARRAY);
|
|
let b: VZV<[u8]> = VarZeroVec::from(U8_2D_SLICE);
|
|
let c: VZV<[u8]> = VarZeroVec::from(&u8_2d_vec);
|
|
assert_eq!(a, U8_2D_SLICE);
|
|
assert_eq!(a, b);
|
|
assert_eq!(a, c);
|
|
let u8_3d_vzv_brackets = &[a.clone(), a.clone()];
|
|
|
|
let a: VZV<ZS<u8>> = VarZeroVec::from(&U8_2D_ARRAY);
|
|
let b: VZV<ZS<u8>> = VarZeroVec::from(U8_2D_SLICE);
|
|
let c: VZV<ZS<u8>> = VarZeroVec::from(&u8_2d_vec);
|
|
let d: VZV<ZS<u8>> = VarZeroVec::from(&u8_2d_zerovec);
|
|
assert_eq!(a, U8_2D_SLICE);
|
|
assert_eq!(a, b);
|
|
assert_eq!(a, c);
|
|
assert_eq!(a, d);
|
|
let u8_3d_vzv_zeroslice = &[a.clone(), a.clone()];
|
|
|
|
let a: VZV<VZS<[u8]>> = VarZeroVec::from(&U8_3D_ARRAY);
|
|
let b: VZV<VZS<[u8]>> = VarZeroVec::from(U8_3D_SLICE);
|
|
let c: VZV<VZS<[u8]>> = VarZeroVec::from(&u8_3d_vec);
|
|
let d: VZV<VZS<[u8]>> = VarZeroVec::from(u8_3d_vzv_brackets);
|
|
assert_eq!(
|
|
a.iter()
|
|
.map(|x| x.iter().map(|y| y.to_vec()).collect::<Vec<Vec<u8>>>())
|
|
.collect::<Vec<Vec<Vec<u8>>>>(),
|
|
u8_3d_vec
|
|
);
|
|
assert_eq!(a, b);
|
|
assert_eq!(a, c);
|
|
assert_eq!(a, d);
|
|
|
|
let a: VZV<VZS<ZS<u8>>> = VarZeroVec::from(&U8_3D_ARRAY);
|
|
let b: VZV<VZS<ZS<u8>>> = VarZeroVec::from(U8_3D_SLICE);
|
|
let c: VZV<VZS<ZS<u8>>> = VarZeroVec::from(&u8_3d_vec);
|
|
let d: VZV<VZS<ZS<u8>>> = VarZeroVec::from(u8_3d_vzv_zeroslice);
|
|
assert_eq!(
|
|
a.iter()
|
|
.map(|x| x
|
|
.iter()
|
|
.map(|y| y.iter().collect::<Vec<u8>>())
|
|
.collect::<Vec<Vec<u8>>>())
|
|
.collect::<Vec<Vec<Vec<u8>>>>(),
|
|
u8_3d_vec
|
|
);
|
|
assert_eq!(a, b);
|
|
assert_eq!(a, c);
|
|
assert_eq!(a, d);
|
|
|
|
let a: VZV<ZS<u32>> = VarZeroVec::from(&U32_2D_ARRAY);
|
|
let b: VZV<ZS<u32>> = VarZeroVec::from(U32_2D_SLICE);
|
|
let c: VZV<ZS<u32>> = VarZeroVec::from(&u32_2d_vec);
|
|
let d: VZV<ZS<u32>> = VarZeroVec::from(&u32_2d_zerovec);
|
|
assert_eq!(a, u32_2d_zerovec);
|
|
assert_eq!(a, b);
|
|
assert_eq!(a, c);
|
|
assert_eq!(a, d);
|
|
let u32_3d_vzv = &[a.clone(), a.clone()];
|
|
|
|
let a: VZV<VZS<ZS<u32>>> = VarZeroVec::from(&U32_3D_ARRAY);
|
|
let b: VZV<VZS<ZS<u32>>> = VarZeroVec::from(U32_3D_SLICE);
|
|
let c: VZV<VZS<ZS<u32>>> = VarZeroVec::from(&u32_3d_vec);
|
|
let d: VZV<VZS<ZS<u32>>> = VarZeroVec::from(u32_3d_vzv);
|
|
assert_eq!(
|
|
a.iter()
|
|
.map(|x| x
|
|
.iter()
|
|
.map(|y| y.iter().collect::<Vec<u32>>())
|
|
.collect::<Vec<Vec<u32>>>())
|
|
.collect::<Vec<Vec<Vec<u32>>>>(),
|
|
u32_3d_vec
|
|
);
|
|
assert_eq!(a, b);
|
|
assert_eq!(a, c);
|
|
assert_eq!(a, d);
|
|
}
|
|
}
|