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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
use crate::ule::AsULE;
use crate::ZeroSlice;
use core::cmp::Ordering;
use core::fmt;
use super::kv::ZeroMapKV;
use super::vecs::ZeroVecLike;
/// A borrowed-only version of [`ZeroMap`](super::ZeroMap)
///
/// This is useful for fully-zero-copy deserialization from non-human-readable
/// serialization formats. It also has the advantage that it can return references that live for
/// the lifetime of the backing buffer as opposed to that of the [`ZeroMapBorrowed`] instance.
///
/// # Examples
///
/// ```
/// use zerovec::maps::ZeroMapBorrowed;
///
/// // Example byte buffer representing the map { 1: "one" }
/// let BINCODE_BYTES: &[u8; 29] = &[
/// 4, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 9, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0,
/// 0, 0, 111, 110, 101,
/// ];
///
/// // Deserializing to ZeroMap requires no heap allocations.
/// let zero_map: ZeroMapBorrowed<u32, str> =
/// bincode::deserialize(BINCODE_BYTES)
/// .expect("Should deserialize successfully");
/// assert_eq!(zero_map.get(&1), Some("one"));
/// ```
///
/// This can be obtained from a [`ZeroMap`](super::ZeroMap) via [`ZeroMap::as_borrowed`](super::ZeroMap::as_borrowed)
pub struct ZeroMapBorrowed<'a, K, V>
where
K: ZeroMapKV<'a>,
V: ZeroMapKV<'a>,
K: ?Sized,
V: ?Sized,
{
pub(crate) keys: &'a <K as ZeroMapKV<'a>>::Slice,
pub(crate) values: &'a <V as ZeroMapKV<'a>>::Slice,
}
impl<'a, K, V> Copy for ZeroMapBorrowed<'a, K, V>
where
K: ZeroMapKV<'a>,
V: ZeroMapKV<'a>,
K: ?Sized,
V: ?Sized,
{
}
impl<'a, K, V> Clone for ZeroMapBorrowed<'a, K, V>
where
K: ZeroMapKV<'a>,
V: ZeroMapKV<'a>,
K: ?Sized,
V: ?Sized,
{
fn clone(&self) -> Self {
*self
}
}
impl<'a, K, V> Default for ZeroMapBorrowed<'a, K, V>
where
K: ZeroMapKV<'a>,
V: ZeroMapKV<'a>,
K::Slice: 'static,
V::Slice: 'static,
K: ?Sized,
V: ?Sized,
{
fn default() -> Self {
Self::new()
}
}
impl<'a, K, V> ZeroMapBorrowed<'a, K, V>
where
K: ZeroMapKV<'a>,
V: ZeroMapKV<'a>,
K::Slice: 'static,
V::Slice: 'static,
K: ?Sized,
V: ?Sized,
{
/// Creates a new, empty `ZeroMapBorrowed<K, V>`.
///
/// Note: Since [`ZeroMapBorrowed`] is not mutable, the return value will be a stub unless
/// converted into a [`ZeroMap`](super::ZeroMap).
///
/// # Examples
///
/// ```
/// use zerovec::maps::ZeroMapBorrowed;
///
/// let zm: ZeroMapBorrowed<u16, str> = ZeroMapBorrowed::new();
/// assert!(zm.is_empty());
/// ```
pub fn new() -> Self {
Self {
keys: K::Container::zvl_new_borrowed(),
values: V::Container::zvl_new_borrowed(),
}
}
}
impl<'a, K, V> ZeroMapBorrowed<'a, K, V>
where
K: ZeroMapKV<'a>,
V: ZeroMapKV<'a>,
K: ?Sized,
V: ?Sized,
{
#[doc(hidden)] // databake internal
pub const unsafe fn from_parts_unchecked(
keys: &'a <K as ZeroMapKV<'a>>::Slice,
values: &'a <V as ZeroMapKV<'a>>::Slice,
) -> Self {
Self { keys, values }
}
/// The number of elements in the [`ZeroMapBorrowed`]
pub fn len(&self) -> usize {
self.values.zvl_len()
}
/// Whether the [`ZeroMapBorrowed`] is empty
pub fn is_empty(&self) -> bool {
self.values.zvl_len() == 0
}
}
impl<'a, K, V> ZeroMapBorrowed<'a, K, V>
where
K: ZeroMapKV<'a> + Ord,
V: ZeroMapKV<'a>,
K: ?Sized,
V: ?Sized,
{
/// Get the value associated with `key`, if it exists.
///
/// This is able to return values that live longer than the map itself
/// since they borrow directly from the backing buffer. This is the
/// primary advantage of using [`ZeroMapBorrowed`](super::ZeroMapBorrowed) over [`ZeroMap`](super::ZeroMap).
///
/// ```rust
/// use zerovec::ZeroMap;
///
/// let mut map = ZeroMap::new();
/// map.insert(&1, "one");
/// map.insert(&2, "two");
/// let borrowed = map.as_borrowed();
/// assert_eq!(borrowed.get(&1), Some("one"));
/// assert_eq!(borrowed.get(&3), None);
/// ```
pub fn get(&self, key: &K) -> Option<&'a V::GetType> {
let index = self.keys.zvl_binary_search(key).ok()?;
self.values.zvl_get(index)
}
/// Binary search the map with `predicate` to find a key, returning the value.
///
/// This is able to return values that live longer than the map itself
/// since they borrow directly from the backing buffer. This is the
/// primary advantage of using [`ZeroMapBorrowed`](super::ZeroMapBorrowed) over [`ZeroMap`](super::ZeroMap).
///
/// ```rust
/// use zerovec::ZeroMap;
///
/// let mut map = ZeroMap::new();
/// map.insert(&1, "one");
/// map.insert(&2, "two");
/// let borrowed = map.as_borrowed();
/// assert_eq!(borrowed.get_by(|probe| probe.cmp(&1)), Some("one"));
/// assert_eq!(borrowed.get_by(|probe| probe.cmp(&3)), None);
/// ```
pub fn get_by(&self, predicate: impl FnMut(&K) -> Ordering) -> Option<&'a V::GetType> {
let index = self.keys.zvl_binary_search_by(predicate).ok()?;
self.values.zvl_get(index)
}
/// Returns whether `key` is contained in this map
///
/// ```rust
/// use zerovec::ZeroMap;
///
/// let mut map = ZeroMap::new();
/// map.insert(&1, "one");
/// map.insert(&2, "two");
/// let borrowed = map.as_borrowed();
/// assert!(borrowed.contains_key(&1));
/// assert!(!borrowed.contains_key(&3));
/// ```
pub fn contains_key(&self, key: &K) -> bool {
self.keys.zvl_binary_search(key).is_ok()
}
}
impl<'a, K, V> ZeroMapBorrowed<'a, K, V>
where
K: ZeroMapKV<'a> + ?Sized,
V: ZeroMapKV<'a> + ?Sized,
{
/// Produce an ordered iterator over key-value pairs
pub fn iter<'b>(
&'b self,
) -> impl Iterator<
Item = (
&'a <K as ZeroMapKV<'a>>::GetType,
&'a <V as ZeroMapKV<'a>>::GetType,
),
> + 'b {
self.iter_keys().zip(self.iter_values())
}
/// Produce an ordered iterator over keys
pub fn iter_keys<'b>(&'b self) -> impl Iterator<Item = &'a <K as ZeroMapKV<'a>>::GetType> + 'b {
#[allow(clippy::unwrap_used)] // idx in 0..keys.zvl_len()
(0..self.keys.zvl_len()).map(move |idx| self.keys.zvl_get(idx).unwrap())
}
/// Produce an iterator over values, ordered by keys
pub fn iter_values<'b>(
&'b self,
) -> impl Iterator<Item = &'a <V as ZeroMapKV<'a>>::GetType> + 'b {
#[allow(clippy::unwrap_used)] // idx in 0..keys.zvl_len() == values.zvl_len()
(0..self.values.zvl_len()).map(move |idx| self.values.zvl_get(idx).unwrap())
}
}
impl<'a, K, V> ZeroMapBorrowed<'a, K, V>
where
K: ZeroMapKV<'a> + Ord + ?Sized,
V: ZeroMapKV<'a, Slice = ZeroSlice<V>> + AsULE + Copy + 'static,
{
/// For cases when `V` is fixed-size, obtain a direct copy of `V` instead of `V::ULE`
pub fn get_copied(&self, key: &K) -> Option<V> {
let index = self.keys.zvl_binary_search(key).ok()?;
self.values.get(index)
}
/// For cases when `V` is fixed-size, obtain a direct copy of `V` instead of `V::ULE`
pub fn get_copied_by(&self, predicate: impl FnMut(&K) -> Ordering) -> Option<V> {
let index = self.keys.zvl_binary_search_by(predicate).ok()?;
self.values.get(index)
}
/// Similar to [`Self::iter()`] except it returns a direct copy of the values instead of references
/// to `V::ULE`, in cases when `V` is fixed-size
pub fn iter_copied_values<'b>(
&'b self,
) -> impl Iterator<Item = (&'b <K as ZeroMapKV<'a>>::GetType, V)> {
(0..self.keys.zvl_len()).map(move |idx| {
(
#[allow(clippy::unwrap_used)] // idx in 0..keys.zvl_len()
self.keys.zvl_get(idx).unwrap(),
#[allow(clippy::unwrap_used)] // idx in 0..keys.zvl_len() = values.zvl_len()
self.values.get(idx).unwrap(),
)
})
}
}
impl<'a, K, V> ZeroMapBorrowed<'a, K, V>
where
K: ZeroMapKV<'a, Slice = ZeroSlice<K>> + AsULE + Copy + Ord + 'static,
V: ZeroMapKV<'a, Slice = ZeroSlice<V>> + AsULE + Copy + 'static,
{
/// Similar to [`Self::iter()`] except it returns a direct copy of the keys values instead of references
/// to `K::ULE` and `V::ULE`, in cases when `K` and `V` are fixed-size
#[allow(clippy::needless_lifetimes)] // Lifetime is necessary in impl Trait
pub fn iter_copied<'b: 'a>(&'b self) -> impl Iterator<Item = (K, V)> + 'b {
let keys = &self.keys;
let values = &self.values;
let len = self.keys.zvl_len();
(0..len).map(move |idx| {
(
#[allow(clippy::unwrap_used)] // idx in 0..keys.zvl_len()
ZeroSlice::get(keys, idx).unwrap(),
#[allow(clippy::unwrap_used)] // idx in 0..keys.zvl_len() = values.zvl_len()
ZeroSlice::get(values, idx).unwrap(),
)
})
}
}
// We can't use the default PartialEq because ZeroMap is invariant
// so otherwise rustc will not automatically allow you to compare ZeroMaps
// with different lifetimes
impl<'a, 'b, K, V> PartialEq<ZeroMapBorrowed<'b, K, V>> for ZeroMapBorrowed<'a, K, V>
where
K: for<'c> ZeroMapKV<'c> + ?Sized,
V: for<'c> ZeroMapKV<'c> + ?Sized,
<K as ZeroMapKV<'a>>::Slice: PartialEq<<K as ZeroMapKV<'b>>::Slice>,
<V as ZeroMapKV<'a>>::Slice: PartialEq<<V as ZeroMapKV<'b>>::Slice>,
{
fn eq(&self, other: &ZeroMapBorrowed<'b, K, V>) -> bool {
self.keys.eq(other.keys) && self.values.eq(other.values)
}
}
impl<'a, K, V> fmt::Debug for ZeroMapBorrowed<'a, K, V>
where
K: ZeroMapKV<'a> + ?Sized,
V: ZeroMapKV<'a> + ?Sized,
K::Slice: fmt::Debug,
V::Slice: fmt::Debug,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
f.debug_struct("ZeroMapBorrowed")
.field("keys", &self.keys)
.field("values", &self.values)
.finish()
}
}