1// This file is part of ICU4X. For terms of use, please see the file
2// called LICENSE at the top level of the ICU4X source tree
3// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
4
5use crate::ule::AsULE;
6use crate::ZeroSlice;
7
8use core::cmp::Ordering;
9use core::fmt;
10
11use super::kv::ZeroMapKV;
12use super::vecs::ZeroVecLike;
13
14/// A borrowed-only version of [`ZeroMap`](super::ZeroMap)
15///
16/// This is useful for fully-zero-copy deserialization from non-human-readable
17/// serialization formats. It also has the advantage that it can return references that live for
18/// the lifetime of the backing buffer as opposed to that of the [`ZeroMapBorrowed`] instance.
19///
20/// # Examples
21///
22/// ```
23/// use zerovec::maps::ZeroMapBorrowed;
24///
25/// // Example byte buffer representing the map { 1: "one" }
26/// let BINCODE_BYTES: &[u8; 29] = &[
27/// 4, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 9, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0,
28/// 0, 0, 111, 110, 101,
29/// ];
30///
31/// // Deserializing to ZeroMap requires no heap allocations.
32/// let zero_map: ZeroMapBorrowed<u32, str> =
33/// bincode::deserialize(BINCODE_BYTES)
34/// .expect("Should deserialize successfully");
35/// assert_eq!(zero_map.get(&1), Some("one"));
36/// ```
37///
38/// This can be obtained from a [`ZeroMap`](super::ZeroMap) via [`ZeroMap::as_borrowed`](super::ZeroMap::as_borrowed)
39pub struct ZeroMapBorrowed<'a, K, V>
40where
41 K: ZeroMapKV<'a>,
42 V: ZeroMapKV<'a>,
43 K: ?Sized,
44 V: ?Sized,
45{
46 pub(crate) keys: &'a <K as ZeroMapKV<'a>>::Slice,
47 pub(crate) values: &'a <V as ZeroMapKV<'a>>::Slice,
48}
49
50impl<'a, K, V> Copy for ZeroMapBorrowed<'a, K, V>
51where
52 K: ZeroMapKV<'a>,
53 V: ZeroMapKV<'a>,
54 K: ?Sized,
55 V: ?Sized,
56{
57}
58impl<'a, K, V> Clone for ZeroMapBorrowed<'a, K, V>
59where
60 K: ZeroMapKV<'a>,
61 V: ZeroMapKV<'a>,
62 K: ?Sized,
63 V: ?Sized,
64{
65 fn clone(&self) -> Self {
66 *self
67 }
68}
69
70impl<'a, K, V> Default for ZeroMapBorrowed<'a, K, V>
71where
72 K: ZeroMapKV<'a>,
73 V: ZeroMapKV<'a>,
74 K::Slice: 'static,
75 V::Slice: 'static,
76 K: ?Sized,
77 V: ?Sized,
78{
79 fn default() -> Self {
80 Self::new()
81 }
82}
83
84impl<'a, K, V> ZeroMapBorrowed<'a, K, V>
85where
86 K: ZeroMapKV<'a>,
87 V: ZeroMapKV<'a>,
88 K::Slice: 'static,
89 V::Slice: 'static,
90 K: ?Sized,
91 V: ?Sized,
92{
93 /// Creates a new, empty `ZeroMapBorrowed<K, V>`.
94 ///
95 /// Note: Since [`ZeroMapBorrowed`] is not mutable, the return value will be a stub unless
96 /// converted into a [`ZeroMap`](super::ZeroMap).
97 ///
98 /// # Examples
99 ///
100 /// ```
101 /// use zerovec::maps::ZeroMapBorrowed;
102 ///
103 /// let zm: ZeroMapBorrowed<u16, str> = ZeroMapBorrowed::new();
104 /// assert!(zm.is_empty());
105 /// ```
106 pub fn new() -> Self {
107 Self {
108 keys: K::Container::zvl_new_borrowed(),
109 values: V::Container::zvl_new_borrowed(),
110 }
111 }
112}
113
114impl<'a, K, V> ZeroMapBorrowed<'a, K, V>
115where
116 K: ZeroMapKV<'a>,
117 V: ZeroMapKV<'a>,
118 K: ?Sized,
119 V: ?Sized,
120{
121 #[doc(hidden)] // databake internal
122 pub const unsafe fn from_parts_unchecked(
123 keys: &'a <K as ZeroMapKV<'a>>::Slice,
124 values: &'a <V as ZeroMapKV<'a>>::Slice,
125 ) -> Self {
126 Self { keys, values }
127 }
128
129 /// The number of elements in the [`ZeroMapBorrowed`]
130 pub fn len(&self) -> usize {
131 self.values.zvl_len()
132 }
133
134 /// Whether the [`ZeroMapBorrowed`] is empty
135 pub fn is_empty(&self) -> bool {
136 self.values.zvl_len() == 0
137 }
138}
139
140impl<'a, K, V> ZeroMapBorrowed<'a, K, V>
141where
142 K: ZeroMapKV<'a> + Ord,
143 V: ZeroMapKV<'a>,
144 K: ?Sized,
145 V: ?Sized,
146{
147 /// Get the value associated with `key`, if it exists.
148 ///
149 /// This is able to return values that live longer than the map itself
150 /// since they borrow directly from the backing buffer. This is the
151 /// primary advantage of using [`ZeroMapBorrowed`](super::ZeroMapBorrowed) over [`ZeroMap`](super::ZeroMap).
152 ///
153 /// ```rust
154 /// use zerovec::ZeroMap;
155 ///
156 /// let mut map = ZeroMap::new();
157 /// map.insert(&1, "one");
158 /// map.insert(&2, "two");
159 /// let borrowed = map.as_borrowed();
160 /// assert_eq!(borrowed.get(&1), Some("one"));
161 /// assert_eq!(borrowed.get(&3), None);
162 /// ```
163 pub fn get(&self, key: &K) -> Option<&'a V::GetType> {
164 let index = self.keys.zvl_binary_search(key).ok()?;
165 self.values.zvl_get(index)
166 }
167
168 /// Binary search the map with `predicate` to find a key, returning the value.
169 ///
170 /// This is able to return values that live longer than the map itself
171 /// since they borrow directly from the backing buffer. This is the
172 /// primary advantage of using [`ZeroMapBorrowed`](super::ZeroMapBorrowed) over [`ZeroMap`](super::ZeroMap).
173 ///
174 /// ```rust
175 /// use zerovec::ZeroMap;
176 ///
177 /// let mut map = ZeroMap::new();
178 /// map.insert(&1, "one");
179 /// map.insert(&2, "two");
180 /// let borrowed = map.as_borrowed();
181 /// assert_eq!(borrowed.get_by(|probe| probe.cmp(&1)), Some("one"));
182 /// assert_eq!(borrowed.get_by(|probe| probe.cmp(&3)), None);
183 /// ```
184 pub fn get_by(&self, predicate: impl FnMut(&K) -> Ordering) -> Option<&'a V::GetType> {
185 let index = self.keys.zvl_binary_search_by(predicate).ok()?;
186 self.values.zvl_get(index)
187 }
188
189 /// Returns whether `key` is contained in this map
190 ///
191 /// ```rust
192 /// use zerovec::ZeroMap;
193 ///
194 /// let mut map = ZeroMap::new();
195 /// map.insert(&1, "one");
196 /// map.insert(&2, "two");
197 /// let borrowed = map.as_borrowed();
198 /// assert!(borrowed.contains_key(&1));
199 /// assert!(!borrowed.contains_key(&3));
200 /// ```
201 pub fn contains_key(&self, key: &K) -> bool {
202 self.keys.zvl_binary_search(key).is_ok()
203 }
204}
205
206impl<'a, K, V> ZeroMapBorrowed<'a, K, V>
207where
208 K: ZeroMapKV<'a> + ?Sized,
209 V: ZeroMapKV<'a> + ?Sized,
210{
211 /// Produce an ordered iterator over key-value pairs
212 pub fn iter<'b>(
213 &'b self,
214 ) -> impl Iterator<
215 Item = (
216 &'a <K as ZeroMapKV<'a>>::GetType,
217 &'a <V as ZeroMapKV<'a>>::GetType,
218 ),
219 > + 'b {
220 self.iter_keys().zip(self.iter_values())
221 }
222
223 /// Produce an ordered iterator over keys
224 pub fn iter_keys<'b>(&'b self) -> impl Iterator<Item = &'a <K as ZeroMapKV<'a>>::GetType> + 'b {
225 #[allow(clippy::unwrap_used)] // idx in 0..keys.zvl_len()
226 (0..self.keys.zvl_len()).map(move |idx| self.keys.zvl_get(idx).unwrap())
227 }
228
229 /// Produce an iterator over values, ordered by keys
230 pub fn iter_values<'b>(
231 &'b self,
232 ) -> impl Iterator<Item = &'a <V as ZeroMapKV<'a>>::GetType> + 'b {
233 #[allow(clippy::unwrap_used)] // idx in 0..keys.zvl_len() == values.zvl_len()
234 (0..self.values.zvl_len()).map(move |idx| self.values.zvl_get(idx).unwrap())
235 }
236}
237
238impl<'a, K, V> ZeroMapBorrowed<'a, K, V>
239where
240 K: ZeroMapKV<'a> + Ord + ?Sized,
241 V: ZeroMapKV<'a, Slice = ZeroSlice<V>> + AsULE + Copy + 'static,
242{
243 /// For cases when `V` is fixed-size, obtain a direct copy of `V` instead of `V::ULE`
244 pub fn get_copied(&self, key: &K) -> Option<V> {
245 let index = self.keys.zvl_binary_search(key).ok()?;
246 self.values.get(index)
247 }
248
249 /// For cases when `V` is fixed-size, obtain a direct copy of `V` instead of `V::ULE`
250 pub fn get_copied_by(&self, predicate: impl FnMut(&K) -> Ordering) -> Option<V> {
251 let index = self.keys.zvl_binary_search_by(predicate).ok()?;
252 self.values.get(index)
253 }
254
255 /// Similar to [`Self::iter()`] except it returns a direct copy of the values instead of references
256 /// to `V::ULE`, in cases when `V` is fixed-size
257 pub fn iter_copied_values<'b>(
258 &'b self,
259 ) -> impl Iterator<Item = (&'b <K as ZeroMapKV<'a>>::GetType, V)> {
260 (0..self.keys.zvl_len()).map(move |idx| {
261 (
262 #[allow(clippy::unwrap_used)] // idx in 0..keys.zvl_len()
263 self.keys.zvl_get(idx).unwrap(),
264 #[allow(clippy::unwrap_used)] // idx in 0..keys.zvl_len() = values.zvl_len()
265 self.values.get(idx).unwrap(),
266 )
267 })
268 }
269}
270
271impl<'a, K, V> ZeroMapBorrowed<'a, K, V>
272where
273 K: ZeroMapKV<'a, Slice = ZeroSlice<K>> + AsULE + Copy + Ord + 'static,
274 V: ZeroMapKV<'a, Slice = ZeroSlice<V>> + AsULE + Copy + 'static,
275{
276 /// Similar to [`Self::iter()`] except it returns a direct copy of the keys values instead of references
277 /// to `K::ULE` and `V::ULE`, in cases when `K` and `V` are fixed-size
278 #[allow(clippy::needless_lifetimes)] // Lifetime is necessary in impl Trait
279 pub fn iter_copied<'b: 'a>(&'b self) -> impl Iterator<Item = (K, V)> + 'b {
280 let keys: &&'a ZeroSlice = &self.keys;
281 let values: &&'a ZeroSlice = &self.values;
282 let len: usize = self.keys.zvl_len();
283 (0..len).map(move |idx: usize| {
284 (
285 #[allow(clippy::unwrap_used)] // idx in 0..keys.zvl_len()
286 ZeroSlice::get(self:keys, index:idx).unwrap(),
287 #[allow(clippy::unwrap_used)] // idx in 0..keys.zvl_len() = values.zvl_len()
288 ZeroSlice::get(self:values, index:idx).unwrap(),
289 )
290 })
291 }
292}
293
294// We can't use the default PartialEq because ZeroMap is invariant
295// so otherwise rustc will not automatically allow you to compare ZeroMaps
296// with different lifetimes
297impl<'a, 'b, K, V> PartialEq<ZeroMapBorrowed<'b, K, V>> for ZeroMapBorrowed<'a, K, V>
298where
299 K: for<'c> dynZeroMapKV<'c> + ?Sized,
300 V: for<'c> dynZeroMapKV<'c> + ?Sized,
301 <K as ZeroMapKV<'a>>::Slice: PartialEq<<K as ZeroMapKV<'b>>::Slice>,
302 <V as ZeroMapKV<'a>>::Slice: PartialEq<<V as ZeroMapKV<'b>>::Slice>,
303{
304 fn eq(&self, other: &ZeroMapBorrowed<'b, K, V>) -> bool {
305 self.keys.eq(other.keys) && self.values.eq(other.values)
306 }
307}
308
309impl<'a, K, V> fmt::Debug for ZeroMapBorrowed<'a, K, V>
310where
311 K: ZeroMapKV<'a> + ?Sized,
312 V: ZeroMapKV<'a> + ?Sized,
313 K::Slice: fmt::Debug,
314 V::Slice: fmt::Debug,
315{
316 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
317 f&mut DebugStruct<'_, '_>.debug_struct("ZeroMapBorrowed")
318 .field("keys", &self.keys)
319 .field(name:"values", &self.values)
320 .finish()
321 }
322}
323