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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 ).
use crate::ule::*;
use alloc::boxed::Box;
use alloc::vec::Vec;
use core::fmt::{self, Display};
use core::ops::Index;
pub(crate) mod borrowed;
pub(crate) mod owned;
#[cfg(feature = "serde")]
mod serde;
mod ule;
pub use borrowed::VarZeroVecBorrowed;
pub use owned::VarZeroVecOwned;
pub use ule::VarZeroVecULE;
/// A zero-copy vector for variable-width types.
///
/// `VarZeroVec<T>` is designed as a drop-in replacement for `Vec<T>` in situations where it is
/// desirable to borrow data from an unaligned byte slice, such as zero-copy deserialization, and
/// where `T`'s data is variable-length (e.g. `String`)
///
/// `T` must implement [`VarULE`], which is already implemented for [`str`] and `[T]` where
/// `T` implements [`ULE`]. It is also implemented on `VarZeroVecULE<T>` for nesting.
///
/// `VarZeroVec<T>` behaves much like [`Cow`](alloc::borrow::Cow), where it can be constructed from owned data
/// but can also borrow from some buffer.
///
/// # How it Works
///
/// `VarZeroVec<T>`, when used with non-human-readable serializers (like `bincode`), will
/// serialize to a specially formatted list of bytes. The format is:
///
/// - 4 bytes for `length` (interpreted as a little-endian u32)
/// - `4 * length` bytes of `indices` (interpreted as little-endian u32)
/// - Remaining bytes for actual `data`
///
/// Each element in the `indices` array points to the starting index of its corresponding
/// data part in the `data` list. The ending index can be calculated from the starting index
/// of the next element (or the length of the slice if dealing with the last element).
///
/// # Safety
///
/// `VarZeroVec<T>` is implemented with a fair amount of unsafe code, but is externally
/// safe to use.
///
/// # Example
///
/// ```rust
/// # use std::str::Utf8Error;
/// # use zerovec::VarZeroVecError;
/// use zerovec::VarZeroVec;
///
/// // The little-endian bytes correspond to the list of strings.
/// let strings = vec!["w".to_owned(), "ω".to_owned(), "文".to_owned(), "𑄃".to_owned()];
/// let bytes = &[
/// 4, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 3, 0, 0, 0,
/// 6, 0, 0, 0, 119, 207, 137, 230, 150, 135, 240, 145, 132, 131,
/// ];
///
/// let zerovec: VarZeroVec<str> = VarZeroVec::parse_byte_slice(bytes)?;
///
/// assert_eq!(zerovec.get(2), Some("文"));
/// assert_eq!(zerovec, &*strings);
/// # Ok::<(), VarZeroVecError<Utf8Error>>(())
/// ```
///
/// Here's another example with `[T]`:
///
/// ```rust
/// # use std::str::Utf8Error;
/// # use zerovec::VarZeroVecError;
/// use zerovec::VarZeroVec;
/// use zerovec::ZeroVec;
/// use zerovec::ule::*;
///
/// // The little-endian bytes correspond to the list of integers.
/// let numbers: Vec<Vec<PlainOldULE<4>>> = vec![
/// vec![12.into(), 25.into(), 38.into()],
/// vec![39179.into(), 100.into()],
/// vec![42.into(), 55555.into()],
/// vec![12345.into(), 54321.into(), 9.into()],
/// ];
/// let bytes = &[4, 0, 0, 0, 0, 0, 0, 0, 12, 0, 0, 0, 20, 0, 0, 0, 28, 0, 0, 0,
/// 12, 0, 0, 0, 25, 0, 0, 0, 38, 0, 0, 0, 11, 153, 0, 0, 100, 0,
/// 0, 0, 42, 0, 0, 0, 3, 217, 0, 0, 57, 48, 0, 0, 49, 212, 0, 0,
/// 9, 0, 0, 0];
///
/// let zerovec: VarZeroVec<[PlainOldULE<4>]> = VarZeroVec::parse_byte_slice(bytes)?;
///
/// assert_eq!(zerovec.get(2).and_then(|v| v.get(1)), Some(&55555.into()));
/// assert_eq!(zerovec, &*numbers);
/// for (zv, v) in zerovec.iter().zip(numbers.iter()) {
/// assert_eq!(zv, v);
/// }
/// # Ok::<(), VarZeroVecError<ULEError<_>>>(())
/// ```
///
///
/// [`VarZeroVec`]s can be nested infinitely, see the docs of [`VarZeroVecULE`]
/// for more information.
///
/// [`ule`]: crate::ule
pub enum VarZeroVec<'a, T: ?Sized> {
/// An allocated VarZeroVec, allowing for mutations.
///
/// # Examples
///
/// ```
/// use zerovec::VarZeroVec;
///
/// let mut vzv = VarZeroVec::<str>::default();
/// vzv.make_mut().push("foo");
/// vzv.make_mut().push("bar");
/// assert!(matches!(vzv, VarZeroVec::Owned(_)));
/// ```
Owned(VarZeroVecOwned<T>),
/// A borrowed VarZeroVec, requiring no allocations.
///
/// If a mutating operation is invoked on VarZeroVec, the Borrowed is converted to Owned.
///
/// # Examples
///
/// ```
/// use zerovec::VarZeroVec;
///
/// let bytes = &[
/// 4, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 3, 0, 0, 0,
/// 6, 0, 0, 0, 119, 207, 137, 230, 150, 135, 240, 145, 132, 131,
/// ];
///
/// let vzv: VarZeroVec<str> = VarZeroVec::parse_byte_slice(bytes).unwrap();
/// assert!(matches!(vzv, VarZeroVec::Borrowed(_)));
/// ```
Borrowed(VarZeroVecBorrowed<'a, T>),
}
impl<'a, T: ?Sized> Clone for VarZeroVec<'a, T> {
fn clone(&self) -> Self {
match *self {
VarZeroVec::Owned(ref o) => o.clone().into(),
VarZeroVec::Borrowed(b) => b.into(),
}
}
}
#[derive(Clone, Debug)]
pub enum VarZeroVecError<E> {
FormatError,
ParseError(E),
}
impl<E: Display> Display for VarZeroVecError<E> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match *self {
Self::FormatError => write!(f, "Incorrect slice format"),
Self::ParseError(ref e) => e.fmt(f),
}
}
}
impl<T: VarULE + ?Sized> fmt::Debug for VarZeroVec<'_, T>
where
T: fmt::Debug,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_list().entries(self.iter()).finish()
}
}
pub type ParseErrorFor<T> = VarZeroVecError<<T as VarULE>::Error>;
impl<E> From<E> for VarZeroVecError<E> {
fn from(e: E) -> Self {
Self::ParseError(e)
}
}
impl<'a, T: ?Sized> From<VarZeroVecOwned<T>> for VarZeroVec<'a, T> {
#[inline]
fn from(other: VarZeroVecOwned<T>) -> Self {
VarZeroVec::Owned(other)
}
}
impl<'a, T: ?Sized> From<VarZeroVecBorrowed<'a, T>> for VarZeroVec<'a, T> {
fn from(other: VarZeroVecBorrowed<'a, T>) -> Self {
VarZeroVec::Borrowed(other)
}
}
impl<'a, T: ?Sized + VarULE> From<VarZeroVec<'a, T>> for VarZeroVecOwned<T> {
#[inline]
fn from(other: VarZeroVec<'a, T>) -> Self {
match other {
VarZeroVec::Owned(o) => o,
VarZeroVec::Borrowed(b) => b.into(),
}
}
}
impl<T: VarULE + ?Sized> Default for VarZeroVec<'_, T> {
fn default() -> Self {
Self::new()
}
}
impl<'a, T: VarULE + ?Sized> VarZeroVec<'a, T> {
/// Construct a new empty [`VarZeroVec`]
#[inline]
pub fn new() -> Self {
VarZeroVecOwned::new().into()
}
/// Obtain a [`VarZeroVecBorrowed`] borrowing from the internal buffer
pub fn as_borrowed<'b>(&'b self) -> VarZeroVecBorrowed<'b, T> {
match self {
VarZeroVec::Owned(ref owned) => owned.as_borrowed(),
VarZeroVec::Borrowed(ref borrowed) => *borrowed,
}
}
/// Get the number of elements in this vector
///
/// # Example
///
/// ```rust
/// # use std::str::Utf8Error;
/// # use zerovec::VarZeroVecError;
/// # use zerovec::VarZeroVec;
///
/// let strings = vec!["foo".to_owned(), "bar".to_owned(),
/// "baz".to_owned(), "quux".to_owned()];
/// let bytes = VarZeroVec::<str>::get_serializable_bytes(&strings).unwrap();
///
/// let mut vec: VarZeroVec<str> = VarZeroVec::parse_byte_slice(&bytes)?;
/// assert_eq!(vec.len(), 4);
/// # Ok::<(), VarZeroVecError<Utf8Error>>(())
/// ```
pub fn len(&self) -> usize {
self.as_borrowed().len()
}
/// Returns `true` if the vector contains no elements.
///
/// # Examples
///
/// ```
/// # use std::str::Utf8Error;
/// # use zerovec::VarZeroVecError;
/// # use zerovec::VarZeroVec;
///
/// let strings: Vec<String> = vec![];
/// let bytes = VarZeroVec::<str>::get_serializable_bytes(&strings).unwrap();
///
/// let mut vec: VarZeroVec<str> = VarZeroVec::parse_byte_slice(&bytes)?;
/// assert!(vec.is_empty());
/// # Ok::<(), VarZeroVecError<Utf8Error>>(())
/// ```
pub fn is_empty(&self) -> bool {
self.as_borrowed().is_empty()
}
/// Parse a VarZeroVec from a slice of the appropriate format
///
/// Slices of the right format can be obtained via [`VarZeroVec::<str>::get_serializable_bytes()`]
/// or [`VarZeroVec::get_encoded_slice()`]
///
/// # Example
///
/// ```rust
/// # use std::str::Utf8Error;
/// # use zerovec::VarZeroVecError;
/// # use zerovec::VarZeroVec;
///
/// let strings = vec!["foo".to_owned(), "bar".to_owned(),
/// "baz".to_owned(), "quux".to_owned()];
/// let bytes = VarZeroVec::<str>::get_serializable_bytes(&strings).unwrap();
///
/// let mut vec: VarZeroVec<str> = VarZeroVec::parse_byte_slice(&bytes)?;
/// assert_eq!(&vec[0], "foo");
/// assert_eq!(&vec[1], "bar");
/// assert_eq!(&vec[2], "baz");
/// assert_eq!(&vec[3], "quux");
/// # Ok::<(), VarZeroVecError<Utf8Error>>(())
/// ```
pub fn parse_byte_slice(slice: &'a [u8]) -> Result<Self, ParseErrorFor<T>> {
if slice.is_empty() {
// does not allocate
return Ok(VarZeroVec::Owned(VarZeroVecOwned::new()));
}
let borrowed = VarZeroVecBorrowed::<T>::parse_byte_slice(slice)?;
Ok(VarZeroVec::Borrowed(borrowed))
}
/// Obtain an iterator over VarZeroVec's elements
///
/// # Example
///
/// ```rust
/// # use std::str::Utf8Error;
/// # use zerovec::VarZeroVecError;
/// # use zerovec::VarZeroVec;
///
/// let strings = vec!["foo".to_owned(), "bar".to_owned(),
/// "baz".to_owned(), "quux".to_owned()];
/// let bytes = VarZeroVec::<str>::get_serializable_bytes(&strings).unwrap();
/// let mut vec: VarZeroVec<str> = VarZeroVec::parse_byte_slice(&bytes)?;
///
/// let mut iter_results: Vec<&str> = vec.iter().collect();
/// assert_eq!(iter_results[0], "foo");
/// assert_eq!(iter_results[1], "bar");
/// assert_eq!(iter_results[2], "baz");
/// assert_eq!(iter_results[3], "quux");
/// # Ok::<(), VarZeroVecError<Utf8Error>>(())
/// ```
pub fn iter<'b: 'a>(&'b self) -> impl Iterator<Item = &'b T> {
self.as_borrowed().iter()
}
/// Get one of VarZeroVec's elements, returning None if the index is out of bounds
///
/// # Example
///
/// ```rust
/// # use std::str::Utf8Error;
/// # use zerovec::VarZeroVecError;
/// # use zerovec::VarZeroVec;
///
/// let strings = vec!["foo".to_owned(), "bar".to_owned(),
/// "baz".to_owned(), "quux".to_owned()];
/// let bytes = VarZeroVec::<str>::get_serializable_bytes(&strings).unwrap();
/// let mut vec: VarZeroVec<str> = VarZeroVec::parse_byte_slice(&bytes)?;
///
/// let mut iter_results: Vec<&str> = vec.iter().collect();
/// assert_eq!(vec.get(0), Some("foo"));
/// assert_eq!(vec.get(1), Some("bar"));
/// assert_eq!(vec.get(2), Some("baz"));
/// assert_eq!(vec.get(3), Some("quux"));
/// assert_eq!(vec.get(4), None);
/// # Ok::<(), VarZeroVecError<Utf8Error>>(())
/// ```
pub fn get(&self, idx: usize) -> Option<&T> {
self.as_borrowed().get(idx)
}
/// Convert this into a mutable vector of the owned `T` type, cloning if necessary.
///
///
/// # Example
///
/// ```rust,ignore
/// # use std::str::Utf8Error;
/// # use zerovec::VarZeroVecError;
/// # use zerovec::VarZeroVec;
///
/// let strings = vec!["foo".to_owned(), "bar".to_owned(),
/// "baz".to_owned(), "quux".to_owned()];
/// let bytes = VarZeroVec::<str>::get_serializable_bytes(&strings).unwrap();
/// let mut vec: VarZeroVec<str> = VarZeroVec::parse_byte_slice(&bytes)?;
///
/// assert_eq!(vec.len(), 4);
/// let mutvec = vec.make_mut();
/// mutvec.push("lorem ipsum".into());
/// mutvec[2] = "dolor sit".into();
/// assert_eq!(&vec[0], "foo");
/// assert_eq!(&vec[1], "bar");
/// assert_eq!(&vec[2], "dolor sit");
/// assert_eq!(&vec[3], "quux");
/// assert_eq!(&vec[4], "lorem ipsum");
/// # Ok::<(), VarZeroVecError<Utf8Error>>(())
/// ```
//
// This function is crate-public for now since we don't yet want to stabilize
// the internal implementation details
pub fn make_mut(&mut self) -> &mut VarZeroVecOwned<T> {
match self {
VarZeroVec::Owned(ref mut vec) => vec,
VarZeroVec::Borrowed(ref borrowed) => {
let new_self = VarZeroVecOwned::from_borrowed(*borrowed);
*self = new_self.into();
// recursion is limited since we are guaranteed to hit the Owned branch
self.make_mut()
}
}
}
/// Converts a borrowed ZeroVec to an owned ZeroVec. No-op if already owned.
///
/// # Example
///
/// ```
/// # use std::str::Utf8Error;
/// # use zerovec::VarZeroVecError;
/// # use zerovec::VarZeroVec;
///
/// let strings = vec!["foo".to_owned(), "bar".to_owned(),
/// "baz".to_owned(), "quux".to_owned()];
/// let bytes = VarZeroVec::<str>::get_serializable_bytes(&strings).unwrap();
/// let mut vec: VarZeroVec<str> = VarZeroVec::parse_byte_slice(&bytes)?;
///
/// assert_eq!(vec.len(), 4);
/// // has 'static lifetime
/// let owned = vec.into_owned();
/// # Ok::<(), VarZeroVecError<Utf8Error>>(())
/// ```
pub fn into_owned(mut self) -> VarZeroVec<'static, T> {
self.make_mut();
match self {
VarZeroVec::Owned(vec) => vec.into(),
_ => unreachable!(),
}
}
/// Obtain this `VarZeroVec` as a [`VarZeroVecULE`]
pub fn as_ule(&self) -> &VarZeroVecULE<T> {
let slice = self.get_encoded_slice();
unsafe {
// safety: the slice is known to come from a valid parsed VZV
VarZeroVecULE::from_byte_slice_unchecked(slice)
}
}
/// Obtain an owned `Vec<Box<T>>` out of this
pub fn to_vec(&self) -> Vec<Box<T>> {
self.as_borrowed().to_vec()
}
/// Obtain the internal encoded slice
///
/// This can be passed back to [`Self::parse_byte_slice()`]
pub fn get_encoded_slice(&self) -> &[u8] {
match self {
VarZeroVec::Owned(ref vec) => vec.entire_slice(),
VarZeroVec::Borrowed(vec) => vec.entire_slice(),
}
}
/// For a slice of `T`, get a list of bytes that can be passed to
/// `parse_byte_slice` to recoup the same data.
///
/// Returns `None` if the slice is too large to be represented in a list of
/// bytes whose length fits in a `u32`.
///
/// # Example
///
/// ```rust
/// # use std::str::Utf8Error;
/// # use zerovec::VarZeroVecError;
/// # use zerovec::VarZeroVec;
///
/// let strings = vec!["foo".to_owned(), "bar".to_owned(), "baz".to_owned()];
/// let bytes = VarZeroVec::<str>::get_serializable_bytes(&strings).unwrap();
///
/// let mut borrowed: VarZeroVec<str> = VarZeroVec::parse_byte_slice(&bytes)?;
/// assert_eq!(borrowed, &*strings);
///
/// # Ok::<(), VarZeroVecError<Utf8Error>>(())
/// ```
///
pub fn get_serializable_bytes<A: custom::EncodeAsVarULE<T>>(elements: &[A]) -> Option<Vec<u8>> {
borrowed::get_serializable_bytes(elements)
}
/// Return whether the [`VarZeroVec`] is operating on owned or borrowed
/// data. [`VarZeroVec::into_owned()`] and [`VarZeroVec::make_mut()`] can
/// be used to force it into an owned type
pub fn is_owned(&self) -> bool {
match self {
VarZeroVec::Owned(..) => true,
VarZeroVec::Borrowed(..) => false,
}
}
}
impl<'a, T> VarZeroVec<'a, T>
where
T: VarULE,
T: ?Sized,
T: Ord,
{
/// Binary searches a sorted `VarZeroVec<T>` for the given element. For more information, see
/// the primitive function [`binary_search`].
///
/// # Example
///
/// ```
/// # use std::str::Utf8Error;
/// # use zerovec::VarZeroVecError;
/// # use zerovec::VarZeroVec;
///
/// let strings = vec!["a".to_owned(), "b".to_owned(),
/// "f".to_owned(), "g".to_owned()];
/// let bytes = VarZeroVec::<str>::get_serializable_bytes(&strings).unwrap();
/// let mut vec: VarZeroVec<str> = VarZeroVec::parse_byte_slice(&bytes)?;
///
/// assert_eq!(vec.binary_search("f"), Ok(2));
/// assert_eq!(vec.binary_search("e"), Err(2));
/// # Ok::<(), VarZeroVecError<Utf8Error>>(())
/// ```
///
/// [`binary_search`]: https://doc.rust-lang.org/std/primitive.slice.html#method.binary_search
#[inline]
pub fn binary_search(&self, x: &T) -> Result<usize, usize> {
self.as_borrowed().binary_search(x)
}
}
impl<'a, T: VarULE + ?Sized> Index<usize> for VarZeroVec<'a, T> {
type Output = T;
fn index(&self, index: usize) -> &Self::Output {
self.get(index).expect("Indexing VarZeroVec out of bounds")
}
}
impl<'a, A, T> From<&'_ [A]> for VarZeroVec<'a, T>
where
T: VarULE,
T: ?Sized,
A: custom::EncodeAsVarULE<T>,
{
fn from(other: &'_ [A]) -> Self {
VarZeroVecOwned::from_elements(other).into()
}
}
impl<'a, 'b, T> PartialEq<VarZeroVec<'b, T>> for VarZeroVec<'a, T>
where
T: VarULE,
T: ?Sized,
T: PartialEq,
{
#[inline]
fn eq(&self, other: &VarZeroVec<'b, T>) -> bool {
// VarULE has an API guarantee that this is equivalent
// to `T::VarULE::eq()`
self.get_encoded_slice().eq(other.get_encoded_slice())
}
}
impl<T, A> PartialEq<&'_ [A]> for VarZeroVec<'_, T>
where
T: VarULE + ?Sized,
T: PartialEq,
A: AsRef<T>,
{
#[inline]
fn eq(&self, other: &&[A]) -> bool {
self.iter().eq(other.iter().map(|t| t.as_ref()))
}
}