zerovec/map/
map.rs

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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 super::*;
6use crate::ule::{AsULE, EncodeAsVarULE, UleError, VarULE};
7use crate::{VarZeroVec, ZeroSlice, ZeroVec};
8use alloc::borrow::Borrow;
9use alloc::boxed::Box;
10use core::cmp::Ordering;
11use core::fmt;
12use core::iter::FromIterator;
13
14/// A zero-copy map datastructure, built on sorted binary-searchable [`ZeroVec`]
15/// and [`VarZeroVec`].
16///
17/// This type, like [`ZeroVec`] and [`VarZeroVec`], is able to zero-copy
18/// deserialize from appropriately formatted byte buffers. It is internally copy-on-write, so it can be mutated
19/// afterwards as necessary.
20///
21/// Internally, a `ZeroMap` is a zero-copy vector for keys paired with a zero-copy vector for
22/// values, sorted by the keys. Therefore, all types used in `ZeroMap` need to work with either
23/// [`ZeroVec`] or [`VarZeroVec`].
24///
25/// This does mean that for fixed-size data, one must use the regular type (`u32`, `u8`, `char`, etc),
26/// whereas for variable-size data, `ZeroMap` will use the dynamically sized version (`str` not `String`,
27/// `ZeroSlice` not `ZeroVec`, `FooULE` not `Foo` for custom types)
28///
29/// # Examples
30///
31/// ```
32/// use zerovec::ZeroMap;
33///
34/// #[derive(serde::Serialize, serde::Deserialize)]
35/// struct Data<'a> {
36///     #[serde(borrow)]
37///     map: ZeroMap<'a, u32, str>,
38/// }
39///
40/// let mut map = ZeroMap::new();
41/// map.insert(&1, "one");
42/// map.insert(&2, "two");
43/// map.insert(&4, "four");
44///
45/// let data = Data { map };
46///
47/// let bincode_bytes =
48///     bincode::serialize(&data).expect("Serialization should be successful");
49///
50/// // Will deserialize without any allocations
51/// let deserialized: Data = bincode::deserialize(&bincode_bytes)
52///     .expect("Deserialization should be successful");
53///
54/// assert_eq!(data.map.get(&1), Some("one"));
55/// assert_eq!(data.map.get(&2), Some("two"));
56/// ```
57///
58/// [`VarZeroVec`]: crate::VarZeroVec
59// ZeroMap has only one invariant: keys.len() == values.len()
60// It is also expected that the keys are sorted, but this is not an invariant. See #1433
61pub struct ZeroMap<'a, K, V>
62where
63    K: ZeroMapKV<'a> + ?Sized,
64    V: ZeroMapKV<'a> + ?Sized,
65{
66    pub(crate) keys: K::Container,
67    pub(crate) values: V::Container,
68}
69
70impl<'a, K, V> Default for ZeroMap<'a, K, V>
71where
72    K: ZeroMapKV<'a> + ?Sized,
73    V: ZeroMapKV<'a> + ?Sized,
74{
75    fn default() -> Self {
76        Self::new()
77    }
78}
79
80impl<'a, K, V> ZeroMap<'a, K, V>
81where
82    K: ZeroMapKV<'a> + ?Sized,
83    V: ZeroMapKV<'a> + ?Sized,
84{
85    /// Creates a new, empty `ZeroMap<K, V>`.
86    ///
87    /// # Examples
88    ///
89    /// ```
90    /// use zerovec::ZeroMap;
91    ///
92    /// let zm: ZeroMap<u16, str> = ZeroMap::new();
93    /// assert!(zm.is_empty());
94    /// ```
95    pub fn new() -> Self {
96        Self {
97            keys: K::Container::zvl_with_capacity(0),
98            values: V::Container::zvl_with_capacity(0),
99        }
100    }
101
102    #[doc(hidden)] // databake internal
103    pub const unsafe fn from_parts_unchecked(keys: K::Container, values: V::Container) -> Self {
104        Self { keys, values }
105    }
106
107    /// Construct a new [`ZeroMap`] with a given capacity
108    pub fn with_capacity(capacity: usize) -> Self {
109        Self {
110            keys: K::Container::zvl_with_capacity(capacity),
111            values: V::Container::zvl_with_capacity(capacity),
112        }
113    }
114
115    /// Obtain a borrowed version of this map
116    pub fn as_borrowed(&'a self) -> ZeroMapBorrowed<'a, K, V> {
117        ZeroMapBorrowed {
118            keys: self.keys.zvl_as_borrowed(),
119            values: self.values.zvl_as_borrowed(),
120        }
121    }
122
123    /// The number of elements in the [`ZeroMap`]
124    pub fn len(&self) -> usize {
125        self.values.zvl_len()
126    }
127
128    /// Whether the [`ZeroMap`] is empty
129    pub fn is_empty(&self) -> bool {
130        self.values.zvl_len() == 0
131    }
132
133    /// Remove all elements from the [`ZeroMap`]
134    pub fn clear(&mut self) {
135        self.keys.zvl_clear();
136        self.values.zvl_clear();
137    }
138
139    /// Reserve capacity for `additional` more elements to be inserted into
140    /// the [`ZeroMap`] to avoid frequent reallocations.
141    ///
142    /// See [`Vec::reserve()`](alloc::vec::Vec::reserve) for more information.
143    pub fn reserve(&mut self, additional: usize) {
144        self.keys.zvl_reserve(additional);
145        self.values.zvl_reserve(additional);
146    }
147}
148impl<'a, K, V> ZeroMap<'a, K, V>
149where
150    K: ZeroMapKV<'a> + ?Sized + Ord,
151    V: ZeroMapKV<'a> + ?Sized,
152{
153    /// Get the value associated with `key`, if it exists.
154    ///
155    /// For fixed-size ([`AsULE`]) `V` types, this _will_ return
156    /// their corresponding [`AsULE::ULE`] type. If you wish to work with the `V`
157    /// type directly, [`Self::get_copied()`] exists for convenience.
158    ///
159    /// ```rust
160    /// use zerovec::ZeroMap;
161    ///
162    /// let mut map = ZeroMap::new();
163    /// map.insert(&1, "one");
164    /// map.insert(&2, "two");
165    /// assert_eq!(map.get(&1), Some("one"));
166    /// assert_eq!(map.get(&3), None);
167    /// ```
168    pub fn get(&self, key: &K) -> Option<&V::GetType> {
169        let index = self.keys.zvl_binary_search(key).ok()?;
170        self.values.zvl_get(index)
171    }
172
173    /// Binary search the map with `predicate` to find a key, returning the value.
174    ///
175    /// ```rust
176    /// use zerovec::ZeroMap;
177    ///
178    /// let mut map = ZeroMap::new();
179    /// map.insert(&1, "one");
180    /// map.insert(&2, "two");
181    /// assert_eq!(map.get_by(|probe| probe.cmp(&1)), Some("one"));
182    /// assert_eq!(map.get_by(|probe| probe.cmp(&3)), None);
183    /// ```
184    pub fn get_by(&self, predicate: impl FnMut(&K) -> Ordering) -> Option<&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    /// assert!(map.contains_key(&1));
198    /// assert!(!map.contains_key(&3));
199    /// ```
200    pub fn contains_key(&self, key: &K) -> bool {
201        self.keys.zvl_binary_search(key).is_ok()
202    }
203
204    /// Insert `value` with `key`, returning the existing value if it exists.
205    ///
206    /// ```rust
207    /// use zerovec::ZeroMap;
208    ///
209    /// let mut map = ZeroMap::new();
210    /// map.insert(&1, "one");
211    /// map.insert(&2, "two");
212    /// assert_eq!(map.get(&1), Some("one"));
213    /// assert_eq!(map.get(&3), None);
214    /// ```
215    pub fn insert(&mut self, key: &K, value: &V) -> Option<V::OwnedType> {
216        match self.keys.zvl_binary_search(key) {
217            Ok(index) => Some(self.values.zvl_replace(index, value)),
218            Err(index) => {
219                self.keys.zvl_insert(index, key);
220                self.values.zvl_insert(index, value);
221                None
222            }
223        }
224    }
225
226    /// Remove the value at `key`, returning it if it exists.
227    ///
228    /// ```rust
229    /// use zerovec::ZeroMap;
230    ///
231    /// let mut map = ZeroMap::new();
232    /// map.insert(&1, "one");
233    /// map.insert(&2, "two");
234    /// assert_eq!(map.remove(&1), Some("one".to_owned().into_boxed_str()));
235    /// assert_eq!(map.get(&1), None);
236    /// ```
237    pub fn remove(&mut self, key: &K) -> Option<V::OwnedType> {
238        let idx = self.keys.zvl_binary_search(key).ok()?;
239        self.keys.zvl_remove(idx);
240        Some(self.values.zvl_remove(idx))
241    }
242
243    /// Appends `value` with `key` to the end of the underlying vector, returning
244    /// `key` and `value` _if it failed_. Useful for extending with an existing
245    /// sorted list.
246    /// ```rust
247    /// use zerovec::ZeroMap;
248    ///
249    /// let mut map = ZeroMap::new();
250    /// assert!(map.try_append(&1, "uno").is_none());
251    /// assert!(map.try_append(&3, "tres").is_none());
252    ///
253    /// let unsuccessful = map.try_append(&3, "tres-updated");
254    /// assert!(unsuccessful.is_some(), "append duplicate of last key");
255    ///
256    /// let unsuccessful = map.try_append(&2, "dos");
257    /// assert!(unsuccessful.is_some(), "append out of order");
258    ///
259    /// assert_eq!(map.get(&1), Some("uno"));
260    ///
261    /// // contains the original value for the key: 3
262    /// assert_eq!(map.get(&3), Some("tres"));
263    ///
264    /// // not appended since it wasn't in order
265    /// assert_eq!(map.get(&2), None);
266    /// ```
267    #[must_use]
268    pub fn try_append<'b>(&mut self, key: &'b K, value: &'b V) -> Option<(&'b K, &'b V)> {
269        if self.keys.zvl_len() != 0 {
270            if let Some(last) = self.keys.zvl_get(self.keys.zvl_len() - 1) {
271                if K::Container::t_cmp_get(key, last) != Ordering::Greater {
272                    return Some((key, value));
273                }
274            }
275        }
276
277        self.keys.zvl_push(key);
278        self.values.zvl_push(value);
279        None
280    }
281}
282
283impl<'a, K, V> ZeroMap<'a, K, V>
284where
285    K: ZeroMapKV<'a> + ?Sized,
286    V: ZeroMapKV<'a> + ?Sized,
287{
288    /// Produce an ordered iterator over key-value pairs
289    pub fn iter<'b>(
290        &'b self,
291    ) -> impl ExactSizeIterator<
292        Item = (
293            &'b <K as ZeroMapKV<'a>>::GetType,
294            &'b <V as ZeroMapKV<'a>>::GetType,
295        ),
296    > {
297        (0..self.keys.zvl_len()).map(move |idx| {
298            (
299                #[allow(clippy::unwrap_used)] // idx is in-range
300                self.keys.zvl_get(idx).unwrap(),
301                #[allow(clippy::unwrap_used)] // idx is in-range
302                self.values.zvl_get(idx).unwrap(),
303            )
304        })
305    }
306
307    /// Produce an ordered iterator over keys
308    pub fn iter_keys<'b>(
309        &'b self,
310    ) -> impl ExactSizeIterator<Item = &'b <K as ZeroMapKV<'a>>::GetType> {
311        #[allow(clippy::unwrap_used)] // idx is in-range
312        (0..self.keys.zvl_len()).map(move |idx| self.keys.zvl_get(idx).unwrap())
313    }
314
315    /// Produce an iterator over values, ordered by keys
316    pub fn iter_values<'b>(
317        &'b self,
318    ) -> impl ExactSizeIterator<Item = &'b <V as ZeroMapKV<'a>>::GetType> {
319        #[allow(clippy::unwrap_used)] // idx is in-range
320        (0..self.values.zvl_len()).map(move |idx| self.values.zvl_get(idx).unwrap())
321    }
322}
323
324impl<'a, K, V> ZeroMap<'a, K, V>
325where
326    K: AsULE + ZeroMapKV<'a, Container = ZeroVec<'a, K>>,
327    V: ZeroMapKV<'a> + ?Sized,
328{
329    /// Cast a `ZeroMap<K, V>` to `ZeroMap<P, V>` where `K` and `P` are [`AsULE`] types
330    /// with the same representation.
331    ///
332    /// # Unchecked Invariants
333    ///
334    /// If `K` and `P` have different ordering semantics, unexpected behavior may occur.
335    pub fn cast_zv_k_unchecked<P>(self) -> ZeroMap<'a, P, V>
336    where
337        P: AsULE<ULE = K::ULE> + ZeroMapKV<'a, Container = ZeroVec<'a, P>>,
338    {
339        ZeroMap {
340            keys: self.keys.cast(),
341            values: self.values,
342        }
343    }
344
345    /// Convert a `ZeroMap<K, V>` to `ZeroMap<P, V>` where `K` and `P` are [`AsULE`] types
346    /// with the same size.
347    ///
348    /// # Unchecked Invariants
349    ///
350    /// If `K` and `P` have different ordering semantics, unexpected behavior may occur.
351    ///
352    /// # Panics
353    ///
354    /// Panics if `K::ULE` and `P::ULE` are not the same size.
355    pub fn try_convert_zv_k_unchecked<P>(self) -> Result<ZeroMap<'a, P, V>, UleError>
356    where
357        P: AsULE + ZeroMapKV<'a, Container = ZeroVec<'a, P>>,
358    {
359        Ok(ZeroMap {
360            keys: self.keys.try_into_converted()?,
361            values: self.values,
362        })
363    }
364}
365
366impl<'a, K, V> ZeroMap<'a, K, V>
367where
368    K: ZeroMapKV<'a> + ?Sized,
369    V: AsULE + ZeroMapKV<'a, Container = ZeroVec<'a, V>>,
370{
371    /// Cast a `ZeroMap<K, V>` to `ZeroMap<K, P>` where `V` and `P` are [`AsULE`] types
372    /// with the same representation.
373    ///
374    /// # Unchecked Invariants
375    ///
376    /// If `V` and `P` have different ordering semantics, unexpected behavior may occur.
377    pub fn cast_zv_v_unchecked<P>(self) -> ZeroMap<'a, K, P>
378    where
379        P: AsULE<ULE = V::ULE> + ZeroMapKV<'a, Container = ZeroVec<'a, P>>,
380    {
381        ZeroMap {
382            keys: self.keys,
383            values: self.values.cast(),
384        }
385    }
386
387    /// Convert a `ZeroMap<K, V>` to `ZeroMap<K, P>` where `V` and `P` are [`AsULE`] types
388    /// with the same size.
389    ///
390    /// # Unchecked Invariants
391    ///
392    /// If `V` and `P` have different ordering semantics, unexpected behavior may occur.
393    ///
394    /// # Panics
395    ///
396    /// Panics if `V::ULE` and `P::ULE` are not the same size.
397    pub fn try_convert_zv_v_unchecked<P>(self) -> Result<ZeroMap<'a, K, P>, UleError>
398    where
399        P: AsULE + ZeroMapKV<'a, Container = ZeroVec<'a, P>>,
400    {
401        Ok(ZeroMap {
402            keys: self.keys,
403            values: self.values.try_into_converted()?,
404        })
405    }
406}
407
408impl<'a, K, V> ZeroMap<'a, K, V>
409where
410    K: ZeroMapKV<'a> + ?Sized + Ord,
411    V: ZeroMapKV<'a, Container = VarZeroVec<'a, V>> + ?Sized,
412    V: VarULE,
413{
414    /// Same as `insert()`, but allows using [EncodeAsVarULE](crate::ule::EncodeAsVarULE)
415    /// types with the value to avoid an extra allocation when dealing with custom ULE types.
416    ///
417    /// ```rust
418    /// use std::borrow::Cow;
419    /// use zerovec::ZeroMap;
420    ///
421    /// #[zerovec::make_varule(PersonULE)]
422    /// #[derive(Clone, Eq, PartialEq, Ord, PartialOrd)]
423    /// struct Person<'a> {
424    ///     age: u8,
425    ///     name: Cow<'a, str>,
426    /// }
427    ///
428    /// let mut map: ZeroMap<u32, PersonULE> = ZeroMap::new();
429    /// map.insert_var_v(
430    ///     &1,
431    ///     &Person {
432    ///         age: 20,
433    ///         name: "Joseph".into(),
434    ///     },
435    /// );
436    /// map.insert_var_v(
437    ///     &1,
438    ///     &Person {
439    ///         age: 35,
440    ///         name: "Carla".into(),
441    ///     },
442    /// );
443    /// assert_eq!(&map.get(&1).unwrap().name, "Carla");
444    /// assert!(map.get(&3).is_none());
445    /// ```
446    pub fn insert_var_v<VE: EncodeAsVarULE<V>>(&mut self, key: &K, value: &VE) -> Option<Box<V>> {
447        match self.keys.zvl_binary_search(key) {
448            Ok(index) => {
449                #[allow(clippy::unwrap_used)] // binary search
450                let ret = self.values.get(index).unwrap().to_boxed();
451                self.values.make_mut().replace(index, value);
452                Some(ret)
453            }
454            Err(index) => {
455                self.keys.zvl_insert(index, key);
456                self.values.make_mut().insert(index, value);
457                None
458            }
459        }
460    }
461
462    // insert_var_k, insert_var_kv are not possible since one cannot perform the binary search with EncodeAsVarULE
463    // though we might be able to do it in the future if we add a trait for cross-Ord requirements
464}
465
466impl<'a, K, V> ZeroMap<'a, K, V>
467where
468    K: ZeroMapKV<'a> + ?Sized + Ord,
469    V: Copy + ZeroMapKV<'a>,
470{
471    /// For cases when `V` is fixed-size, obtain a direct copy of `V` instead of `V::ULE`.
472    ///
473    /// # Examples
474    ///
475    /// ```rust
476    /// use zerovec::ZeroMap;
477    ///
478    /// let mut map = ZeroMap::new();
479    /// map.insert(&1, &'a');
480    /// map.insert(&2, &'b');
481    /// assert_eq!(map.get_copied(&1), Some('a'));
482    /// assert_eq!(map.get_copied(&3), None);
483    #[inline]
484    pub fn get_copied(&self, key: &K) -> Option<V> {
485        let index = self.keys.zvl_binary_search(key).ok()?;
486        self.get_copied_at(index)
487    }
488
489    /// Binary search the map with `predicate` to find a key, returning the value.
490    ///
491    /// For cases when `V` is fixed-size, use this method to obtain a direct copy of `V`
492    /// instead of `V::ULE`.
493    ///
494    /// # Examples
495    ///
496    /// ```rust
497    /// use zerovec::ZeroMap;
498    ///
499    /// let mut map = ZeroMap::new();
500    /// map.insert(&1, &'a');
501    /// map.insert(&2, &'b');
502    /// assert_eq!(map.get_copied_by(|probe| probe.cmp(&1)), Some('a'));
503    /// assert_eq!(map.get_copied_by(|probe| probe.cmp(&3)), None);
504    /// ```
505    #[inline]
506    pub fn get_copied_by(&self, predicate: impl FnMut(&K) -> Ordering) -> Option<V> {
507        let index = self.keys.zvl_binary_search_by(predicate).ok()?;
508        self.get_copied_at(index)
509    }
510
511    fn get_copied_at(&self, index: usize) -> Option<V> {
512        let ule = self.values.zvl_get(index)?;
513        let mut result = Option::<V>::None;
514        V::Container::zvl_get_as_t(ule, |v| result.replace(*v));
515        #[allow(clippy::unwrap_used)] // `zvl_get_as_t` guarantees that the callback is invoked
516        Some(result.unwrap())
517    }
518}
519
520impl<'a, K, V> ZeroMap<'a, K, V>
521where
522    K: ZeroMapKV<'a> + ?Sized,
523    V: AsULE + ZeroMapKV<'a, Container = ZeroVec<'a, V>>,
524{
525    /// Similar to [`Self::iter()`] except it returns a direct copy of the values instead of references
526    /// to `V::ULE`, in cases when `V` is fixed-size
527    pub fn iter_copied_values<'b>(
528        &'b self,
529    ) -> impl Iterator<Item = (&'b <K as ZeroMapKV<'a>>::GetType, V)> {
530        (0..self.keys.zvl_len()).map(move |idx| {
531            (
532                #[allow(clippy::unwrap_used)] // idx in 0..keys.zvl_len()
533                self.keys.zvl_get(idx).unwrap(),
534                #[allow(clippy::unwrap_used)] // idx in 0..keys.zvl_len() = values.zvl_len()
535                ZeroSlice::get(&*self.values, idx).unwrap(),
536            )
537        })
538    }
539}
540
541impl<'a, K, V> ZeroMap<'a, K, V>
542where
543    K: AsULE + ZeroMapKV<'a, Container = ZeroVec<'a, K>>,
544    V: AsULE + ZeroMapKV<'a, Container = ZeroVec<'a, V>>,
545{
546    /// Similar to [`Self::iter()`] except it returns a direct copy of the keys values instead of references
547    /// to `K::ULE` and `V::ULE`, in cases when `K` and `V` are fixed-size
548    #[allow(clippy::needless_lifetimes)] // Lifetime is necessary in impl Trait
549    pub fn iter_copied<'b>(&'b self) -> impl Iterator<Item = (K, V)> + 'b {
550        let keys = &self.keys;
551        let values = &self.values;
552        (0..keys.len()).map(move |idx| {
553            (
554                #[allow(clippy::unwrap_used)] // idx in 0..keys.zvl_len()
555                ZeroSlice::get(&**keys, idx).unwrap(),
556                #[allow(clippy::unwrap_used)] // idx in 0..keys.zvl_len() = values.zvl_len()
557                ZeroSlice::get(&**values, idx).unwrap(),
558            )
559        })
560    }
561}
562
563impl<'a, K, V> From<ZeroMapBorrowed<'a, K, V>> for ZeroMap<'a, K, V>
564where
565    K: ZeroMapKV<'a>,
566    V: ZeroMapKV<'a>,
567    K: ?Sized,
568    V: ?Sized,
569{
570    fn from(other: ZeroMapBorrowed<'a, K, V>) -> Self {
571        Self {
572            keys: K::Container::zvl_from_borrowed(other.keys),
573            values: V::Container::zvl_from_borrowed(other.values),
574        }
575    }
576}
577
578// We can't use the default PartialEq because ZeroMap is invariant
579// so otherwise rustc will not automatically allow you to compare ZeroMaps
580// with different lifetimes
581impl<'a, 'b, K, V> PartialEq<ZeroMap<'b, K, V>> for ZeroMap<'a, K, V>
582where
583    K: for<'c> ZeroMapKV<'c> + ?Sized,
584    V: for<'c> ZeroMapKV<'c> + ?Sized,
585    <K as ZeroMapKV<'a>>::Container: PartialEq<<K as ZeroMapKV<'b>>::Container>,
586    <V as ZeroMapKV<'a>>::Container: PartialEq<<V as ZeroMapKV<'b>>::Container>,
587{
588    fn eq(&self, other: &ZeroMap<'b, K, V>) -> bool {
589        self.keys.eq(&other.keys) && self.values.eq(&other.values)
590    }
591}
592
593impl<'a, K, V> fmt::Debug for ZeroMap<'a, K, V>
594where
595    K: ZeroMapKV<'a> + ?Sized,
596    V: ZeroMapKV<'a> + ?Sized,
597    <K as ZeroMapKV<'a>>::Container: fmt::Debug,
598    <V as ZeroMapKV<'a>>::Container: fmt::Debug,
599{
600    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
601        f.debug_struct("ZeroMap")
602            .field("keys", &self.keys)
603            .field("values", &self.values)
604            .finish()
605    }
606}
607
608impl<'a, K, V> Clone for ZeroMap<'a, K, V>
609where
610    K: ZeroMapKV<'a> + ?Sized,
611    V: ZeroMapKV<'a> + ?Sized,
612    <K as ZeroMapKV<'a>>::Container: Clone,
613    <V as ZeroMapKV<'a>>::Container: Clone,
614{
615    fn clone(&self) -> Self {
616        Self {
617            keys: self.keys.clone(),
618            values: self.values.clone(),
619        }
620    }
621}
622
623impl<'a, A, B, K, V> FromIterator<(A, B)> for ZeroMap<'a, K, V>
624where
625    A: Borrow<K>,
626    B: Borrow<V>,
627    K: ZeroMapKV<'a> + ?Sized + Ord,
628    V: ZeroMapKV<'a> + ?Sized,
629{
630    fn from_iter<T>(iter: T) -> Self
631    where
632        T: IntoIterator<Item = (A, B)>,
633    {
634        let iter = iter.into_iter();
635        let mut map = match iter.size_hint() {
636            (_, Some(upper)) => Self::with_capacity(upper),
637            (lower, None) => Self::with_capacity(lower),
638        };
639
640        for (key, value) in iter {
641            if let Some((key, value)) = map.try_append(key.borrow(), value.borrow()) {
642                map.insert(key, value);
643            }
644        }
645        map
646    }
647}
zerovec/map/map.rs

zerovec/map/
map.rs
