indexmap/map/
slice.rs

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1use super::{
2    Bucket, IndexMap, IntoIter, IntoKeys, IntoValues, Iter, IterMut, Keys, Values, ValuesMut,
3};
4use crate::util::{slice_eq, try_simplify_range};
5use crate::GetDisjointMutError;
6
7use alloc::boxed::Box;
8use alloc::vec::Vec;
9use core::cmp::Ordering;
10use core::fmt;
11use core::hash::{Hash, Hasher};
12use core::ops::{self, Bound, Index, IndexMut, RangeBounds};
13
14/// A dynamically-sized slice of key-value pairs in an [`IndexMap`].
15///
16/// This supports indexed operations much like a `[(K, V)]` slice,
17/// but not any hashed operations on the map keys.
18///
19/// Unlike `IndexMap`, `Slice` does consider the order for [`PartialEq`]
20/// and [`Eq`], and it also implements [`PartialOrd`], [`Ord`], and [`Hash`].
21#[repr(transparent)]
22pub struct Slice<K, V> {
23    pub(crate) entries: [Bucket<K, V>],
24}
25
26// SAFETY: `Slice<K, V>` is a transparent wrapper around `[Bucket<K, V>]`,
27// and reference lifetimes are bound together in function signatures.
28#[allow(unsafe_code)]
29impl<K, V> Slice<K, V> {
30    pub(super) const fn from_slice(entries: &[Bucket<K, V>]) -> &Self {
31        unsafe { &*(entries as *const [Bucket<K, V>] as *const Self) }
32    }
33
34    pub(super) fn from_mut_slice(entries: &mut [Bucket<K, V>]) -> &mut Self {
35        unsafe { &mut *(entries as *mut [Bucket<K, V>] as *mut Self) }
36    }
37
38    pub(super) fn from_boxed(entries: Box<[Bucket<K, V>]>) -> Box<Self> {
39        unsafe { Box::from_raw(Box::into_raw(entries) as *mut Self) }
40    }
41
42    fn into_boxed(self: Box<Self>) -> Box<[Bucket<K, V>]> {
43        unsafe { Box::from_raw(Box::into_raw(self) as *mut [Bucket<K, V>]) }
44    }
45}
46
47impl<K, V> Slice<K, V> {
48    pub(crate) fn into_entries(self: Box<Self>) -> Vec<Bucket<K, V>> {
49        self.into_boxed().into_vec()
50    }
51
52    /// Returns an empty slice.
53    pub const fn new<'a>() -> &'a Self {
54        Self::from_slice(&[])
55    }
56
57    /// Returns an empty mutable slice.
58    pub fn new_mut<'a>() -> &'a mut Self {
59        Self::from_mut_slice(&mut [])
60    }
61
62    /// Return the number of key-value pairs in the map slice.
63    #[inline]
64    pub const fn len(&self) -> usize {
65        self.entries.len()
66    }
67
68    /// Returns true if the map slice contains no elements.
69    #[inline]
70    pub const fn is_empty(&self) -> bool {
71        self.entries.is_empty()
72    }
73
74    /// Get a key-value pair by index.
75    ///
76    /// Valid indices are `0 <= index < self.len()`.
77    pub fn get_index(&self, index: usize) -> Option<(&K, &V)> {
78        self.entries.get(index).map(Bucket::refs)
79    }
80
81    /// Get a key-value pair by index, with mutable access to the value.
82    ///
83    /// Valid indices are `0 <= index < self.len()`.
84    pub fn get_index_mut(&mut self, index: usize) -> Option<(&K, &mut V)> {
85        self.entries.get_mut(index).map(Bucket::ref_mut)
86    }
87
88    /// Returns a slice of key-value pairs in the given range of indices.
89    ///
90    /// Valid indices are `0 <= index < self.len()`.
91    pub fn get_range<R: RangeBounds<usize>>(&self, range: R) -> Option<&Self> {
92        let range = try_simplify_range(range, self.entries.len())?;
93        self.entries.get(range).map(Slice::from_slice)
94    }
95
96    /// Returns a mutable slice of key-value pairs in the given range of indices.
97    ///
98    /// Valid indices are `0 <= index < self.len()`.
99    pub fn get_range_mut<R: RangeBounds<usize>>(&mut self, range: R) -> Option<&mut Self> {
100        let range = try_simplify_range(range, self.entries.len())?;
101        self.entries.get_mut(range).map(Slice::from_mut_slice)
102    }
103
104    /// Get the first key-value pair.
105    pub fn first(&self) -> Option<(&K, &V)> {
106        self.entries.first().map(Bucket::refs)
107    }
108
109    /// Get the first key-value pair, with mutable access to the value.
110    pub fn first_mut(&mut self) -> Option<(&K, &mut V)> {
111        self.entries.first_mut().map(Bucket::ref_mut)
112    }
113
114    /// Get the last key-value pair.
115    pub fn last(&self) -> Option<(&K, &V)> {
116        self.entries.last().map(Bucket::refs)
117    }
118
119    /// Get the last key-value pair, with mutable access to the value.
120    pub fn last_mut(&mut self) -> Option<(&K, &mut V)> {
121        self.entries.last_mut().map(Bucket::ref_mut)
122    }
123
124    /// Divides one slice into two at an index.
125    ///
126    /// ***Panics*** if `index > len`.
127    #[track_caller]
128    pub fn split_at(&self, index: usize) -> (&Self, &Self) {
129        let (first, second) = self.entries.split_at(index);
130        (Self::from_slice(first), Self::from_slice(second))
131    }
132
133    /// Divides one mutable slice into two at an index.
134    ///
135    /// ***Panics*** if `index > len`.
136    #[track_caller]
137    pub fn split_at_mut(&mut self, index: usize) -> (&mut Self, &mut Self) {
138        let (first, second) = self.entries.split_at_mut(index);
139        (Self::from_mut_slice(first), Self::from_mut_slice(second))
140    }
141
142    /// Returns the first key-value pair and the rest of the slice,
143    /// or `None` if it is empty.
144    pub fn split_first(&self) -> Option<((&K, &V), &Self)> {
145        if let [first, rest @ ..] = &self.entries {
146            Some((first.refs(), Self::from_slice(rest)))
147        } else {
148            None
149        }
150    }
151
152    /// Returns the first key-value pair and the rest of the slice,
153    /// with mutable access to the value, or `None` if it is empty.
154    pub fn split_first_mut(&mut self) -> Option<((&K, &mut V), &mut Self)> {
155        if let [first, rest @ ..] = &mut self.entries {
156            Some((first.ref_mut(), Self::from_mut_slice(rest)))
157        } else {
158            None
159        }
160    }
161
162    /// Returns the last key-value pair and the rest of the slice,
163    /// or `None` if it is empty.
164    pub fn split_last(&self) -> Option<((&K, &V), &Self)> {
165        if let [rest @ .., last] = &self.entries {
166            Some((last.refs(), Self::from_slice(rest)))
167        } else {
168            None
169        }
170    }
171
172    /// Returns the last key-value pair and the rest of the slice,
173    /// with mutable access to the value, or `None` if it is empty.
174    pub fn split_last_mut(&mut self) -> Option<((&K, &mut V), &mut Self)> {
175        if let [rest @ .., last] = &mut self.entries {
176            Some((last.ref_mut(), Self::from_mut_slice(rest)))
177        } else {
178            None
179        }
180    }
181
182    /// Return an iterator over the key-value pairs of the map slice.
183    pub fn iter(&self) -> Iter<'_, K, V> {
184        Iter::new(&self.entries)
185    }
186
187    /// Return an iterator over the key-value pairs of the map slice.
188    pub fn iter_mut(&mut self) -> IterMut<'_, K, V> {
189        IterMut::new(&mut self.entries)
190    }
191
192    /// Return an iterator over the keys of the map slice.
193    pub fn keys(&self) -> Keys<'_, K, V> {
194        Keys::new(&self.entries)
195    }
196
197    /// Return an owning iterator over the keys of the map slice.
198    pub fn into_keys(self: Box<Self>) -> IntoKeys<K, V> {
199        IntoKeys::new(self.into_entries())
200    }
201
202    /// Return an iterator over the values of the map slice.
203    pub fn values(&self) -> Values<'_, K, V> {
204        Values::new(&self.entries)
205    }
206
207    /// Return an iterator over mutable references to the the values of the map slice.
208    pub fn values_mut(&mut self) -> ValuesMut<'_, K, V> {
209        ValuesMut::new(&mut self.entries)
210    }
211
212    /// Return an owning iterator over the values of the map slice.
213    pub fn into_values(self: Box<Self>) -> IntoValues<K, V> {
214        IntoValues::new(self.into_entries())
215    }
216
217    /// Search over a sorted map for a key.
218    ///
219    /// Returns the position where that key is present, or the position where it can be inserted to
220    /// maintain the sort. See [`slice::binary_search`] for more details.
221    ///
222    /// Computes in **O(log(n))** time, which is notably less scalable than looking the key up in
223    /// the map this is a slice from using [`IndexMap::get_index_of`], but this can also position
224    /// missing keys.
225    pub fn binary_search_keys(&self, x: &K) -> Result<usize, usize>
226    where
227        K: Ord,
228    {
229        self.binary_search_by(|p, _| p.cmp(x))
230    }
231
232    /// Search over a sorted map with a comparator function.
233    ///
234    /// Returns the position where that value is present, or the position where it can be inserted
235    /// to maintain the sort. See [`slice::binary_search_by`] for more details.
236    ///
237    /// Computes in **O(log(n))** time.
238    #[inline]
239    pub fn binary_search_by<'a, F>(&'a self, mut f: F) -> Result<usize, usize>
240    where
241        F: FnMut(&'a K, &'a V) -> Ordering,
242    {
243        self.entries.binary_search_by(move |a| f(&a.key, &a.value))
244    }
245
246    /// Search over a sorted map with an extraction function.
247    ///
248    /// Returns the position where that value is present, or the position where it can be inserted
249    /// to maintain the sort. See [`slice::binary_search_by_key`] for more details.
250    ///
251    /// Computes in **O(log(n))** time.
252    #[inline]
253    pub fn binary_search_by_key<'a, B, F>(&'a self, b: &B, mut f: F) -> Result<usize, usize>
254    where
255        F: FnMut(&'a K, &'a V) -> B,
256        B: Ord,
257    {
258        self.binary_search_by(|k, v| f(k, v).cmp(b))
259    }
260
261    /// Returns the index of the partition point of a sorted map according to the given predicate
262    /// (the index of the first element of the second partition).
263    ///
264    /// See [`slice::partition_point`] for more details.
265    ///
266    /// Computes in **O(log(n))** time.
267    #[must_use]
268    pub fn partition_point<P>(&self, mut pred: P) -> usize
269    where
270        P: FnMut(&K, &V) -> bool,
271    {
272        self.entries
273            .partition_point(move |a| pred(&a.key, &a.value))
274    }
275
276    /// Get an array of `N` key-value pairs by `N` indices
277    ///
278    /// Valid indices are *0 <= index < self.len()* and each index needs to be unique.
279    pub fn get_disjoint_mut<const N: usize>(
280        &mut self,
281        indices: [usize; N],
282    ) -> Result<[(&K, &mut V); N], GetDisjointMutError> {
283        let indices = indices.map(Some);
284        let key_values = self.get_disjoint_opt_mut(indices)?;
285        Ok(key_values.map(Option::unwrap))
286    }
287
288    #[allow(unsafe_code)]
289    pub(crate) fn get_disjoint_opt_mut<const N: usize>(
290        &mut self,
291        indices: [Option<usize>; N],
292    ) -> Result<[Option<(&K, &mut V)>; N], GetDisjointMutError> {
293        // SAFETY: Can't allow duplicate indices as we would return several mutable refs to the same data.
294        let len = self.len();
295        for i in 0..N {
296            if let Some(idx) = indices[i] {
297                if idx >= len {
298                    return Err(GetDisjointMutError::IndexOutOfBounds);
299                } else if indices[..i].contains(&Some(idx)) {
300                    return Err(GetDisjointMutError::OverlappingIndices);
301                }
302            }
303        }
304
305        let entries_ptr = self.entries.as_mut_ptr();
306        let out = indices.map(|idx_opt| {
307            match idx_opt {
308                Some(idx) => {
309                    // SAFETY: The base pointer is valid as it comes from a slice and the reference is always
310                    // in-bounds & unique as we've already checked the indices above.
311                    let kv = unsafe { (*(entries_ptr.add(idx))).ref_mut() };
312                    Some(kv)
313                }
314                None => None,
315            }
316        });
317
318        Ok(out)
319    }
320}
321
322impl<'a, K, V> IntoIterator for &'a Slice<K, V> {
323    type IntoIter = Iter<'a, K, V>;
324    type Item = (&'a K, &'a V);
325
326    fn into_iter(self) -> Self::IntoIter {
327        self.iter()
328    }
329}
330
331impl<'a, K, V> IntoIterator for &'a mut Slice<K, V> {
332    type IntoIter = IterMut<'a, K, V>;
333    type Item = (&'a K, &'a mut V);
334
335    fn into_iter(self) -> Self::IntoIter {
336        self.iter_mut()
337    }
338}
339
340impl<K, V> IntoIterator for Box<Slice<K, V>> {
341    type IntoIter = IntoIter<K, V>;
342    type Item = (K, V);
343
344    fn into_iter(self) -> Self::IntoIter {
345        IntoIter::new(self.into_entries())
346    }
347}
348
349impl<K, V> Default for &'_ Slice<K, V> {
350    fn default() -> Self {
351        Slice::from_slice(&[])
352    }
353}
354
355impl<K, V> Default for &'_ mut Slice<K, V> {
356    fn default() -> Self {
357        Slice::from_mut_slice(&mut [])
358    }
359}
360
361impl<K, V> Default for Box<Slice<K, V>> {
362    fn default() -> Self {
363        Slice::from_boxed(Box::default())
364    }
365}
366
367impl<K: Clone, V: Clone> Clone for Box<Slice<K, V>> {
368    fn clone(&self) -> Self {
369        Slice::from_boxed(self.entries.to_vec().into_boxed_slice())
370    }
371}
372
373impl<K: Copy, V: Copy> From<&Slice<K, V>> for Box<Slice<K, V>> {
374    fn from(slice: &Slice<K, V>) -> Self {
375        Slice::from_boxed(Box::from(&slice.entries))
376    }
377}
378
379impl<K: fmt::Debug, V: fmt::Debug> fmt::Debug for Slice<K, V> {
380    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
381        f.debug_list().entries(self).finish()
382    }
383}
384
385impl<K, V, K2, V2> PartialEq<Slice<K2, V2>> for Slice<K, V>
386where
387    K: PartialEq<K2>,
388    V: PartialEq<V2>,
389{
390    fn eq(&self, other: &Slice<K2, V2>) -> bool {
391        slice_eq(&self.entries, &other.entries, |b1, b2| {
392            b1.key == b2.key && b1.value == b2.value
393        })
394    }
395}
396
397impl<K, V, K2, V2> PartialEq<[(K2, V2)]> for Slice<K, V>
398where
399    K: PartialEq<K2>,
400    V: PartialEq<V2>,
401{
402    fn eq(&self, other: &[(K2, V2)]) -> bool {
403        slice_eq(&self.entries, other, |b, t| b.key == t.0 && b.value == t.1)
404    }
405}
406
407impl<K, V, K2, V2> PartialEq<Slice<K2, V2>> for [(K, V)]
408where
409    K: PartialEq<K2>,
410    V: PartialEq<V2>,
411{
412    fn eq(&self, other: &Slice<K2, V2>) -> bool {
413        slice_eq(self, &other.entries, |t, b| t.0 == b.key && t.1 == b.value)
414    }
415}
416
417impl<K, V, K2, V2, const N: usize> PartialEq<[(K2, V2); N]> for Slice<K, V>
418where
419    K: PartialEq<K2>,
420    V: PartialEq<V2>,
421{
422    fn eq(&self, other: &[(K2, V2); N]) -> bool {
423        <Self as PartialEq<[_]>>::eq(self, other)
424    }
425}
426
427impl<K, V, const N: usize, K2, V2> PartialEq<Slice<K2, V2>> for [(K, V); N]
428where
429    K: PartialEq<K2>,
430    V: PartialEq<V2>,
431{
432    fn eq(&self, other: &Slice<K2, V2>) -> bool {
433        <[_] as PartialEq<_>>::eq(self, other)
434    }
435}
436
437impl<K: Eq, V: Eq> Eq for Slice<K, V> {}
438
439impl<K: PartialOrd, V: PartialOrd> PartialOrd for Slice<K, V> {
440    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
441        self.iter().partial_cmp(other)
442    }
443}
444
445impl<K: Ord, V: Ord> Ord for Slice<K, V> {
446    fn cmp(&self, other: &Self) -> Ordering {
447        self.iter().cmp(other)
448    }
449}
450
451impl<K: Hash, V: Hash> Hash for Slice<K, V> {
452    fn hash<H: Hasher>(&self, state: &mut H) {
453        self.len().hash(state);
454        for (key, value) in self {
455            key.hash(state);
456            value.hash(state);
457        }
458    }
459}
460
461impl<K, V> Index<usize> for Slice<K, V> {
462    type Output = V;
463
464    fn index(&self, index: usize) -> &V {
465        &self.entries[index].value
466    }
467}
468
469impl<K, V> IndexMut<usize> for Slice<K, V> {
470    fn index_mut(&mut self, index: usize) -> &mut V {
471        &mut self.entries[index].value
472    }
473}
474
475// We can't have `impl<I: RangeBounds<usize>> Index<I>` because that conflicts
476// both upstream with `Index<usize>` and downstream with `Index<&Q>`.
477// Instead, we repeat the implementations for all the core range types.
478macro_rules! impl_index {
479    ($($range:ty),*) => {$(
480        impl<K, V, S> Index<$range> for IndexMap<K, V, S> {
481            type Output = Slice<K, V>;
482
483            fn index(&self, range: $range) -> &Self::Output {
484                Slice::from_slice(&self.as_entries()[range])
485            }
486        }
487
488        impl<K, V, S> IndexMut<$range> for IndexMap<K, V, S> {
489            fn index_mut(&mut self, range: $range) -> &mut Self::Output {
490                Slice::from_mut_slice(&mut self.as_entries_mut()[range])
491            }
492        }
493
494        impl<K, V> Index<$range> for Slice<K, V> {
495            type Output = Slice<K, V>;
496
497            fn index(&self, range: $range) -> &Self {
498                Self::from_slice(&self.entries[range])
499            }
500        }
501
502        impl<K, V> IndexMut<$range> for Slice<K, V> {
503            fn index_mut(&mut self, range: $range) -> &mut Self {
504                Self::from_mut_slice(&mut self.entries[range])
505            }
506        }
507    )*}
508}
509impl_index!(
510    ops::Range<usize>,
511    ops::RangeFrom<usize>,
512    ops::RangeFull,
513    ops::RangeInclusive<usize>,
514    ops::RangeTo<usize>,
515    ops::RangeToInclusive<usize>,
516    (Bound<usize>, Bound<usize>)
517);
518
519#[cfg(test)]
520mod tests {
521    use super::*;
522
523    #[test]
524    fn slice_index() {
525        fn check(
526            vec_slice: &[(i32, i32)],
527            map_slice: &Slice<i32, i32>,
528            sub_slice: &Slice<i32, i32>,
529        ) {
530            assert_eq!(map_slice as *const _, sub_slice as *const _);
531            itertools::assert_equal(
532                vec_slice.iter().copied(),
533                map_slice.iter().map(|(&k, &v)| (k, v)),
534            );
535            itertools::assert_equal(vec_slice.iter().map(|(k, _)| k), map_slice.keys());
536            itertools::assert_equal(vec_slice.iter().map(|(_, v)| v), map_slice.values());
537        }
538
539        let vec: Vec<(i32, i32)> = (0..10).map(|i| (i, i * i)).collect();
540        let map: IndexMap<i32, i32> = vec.iter().cloned().collect();
541        let slice = map.as_slice();
542
543        // RangeFull
544        check(&vec[..], &map[..], &slice[..]);
545
546        for i in 0usize..10 {
547            // Index
548            assert_eq!(vec[i].1, map[i]);
549            assert_eq!(vec[i].1, slice[i]);
550            assert_eq!(map[&(i as i32)], map[i]);
551            assert_eq!(map[&(i as i32)], slice[i]);
552
553            // RangeFrom
554            check(&vec[i..], &map[i..], &slice[i..]);
555
556            // RangeTo
557            check(&vec[..i], &map[..i], &slice[..i]);
558
559            // RangeToInclusive
560            check(&vec[..=i], &map[..=i], &slice[..=i]);
561
562            // (Bound<usize>, Bound<usize>)
563            let bounds = (Bound::Excluded(i), Bound::Unbounded);
564            check(&vec[i + 1..], &map[bounds], &slice[bounds]);
565
566            for j in i..=10 {
567                // Range
568                check(&vec[i..j], &map[i..j], &slice[i..j]);
569            }
570
571            for j in i..10 {
572                // RangeInclusive
573                check(&vec[i..=j], &map[i..=j], &slice[i..=j]);
574            }
575        }
576    }
577
578    #[test]
579    fn slice_index_mut() {
580        fn check_mut(
581            vec_slice: &[(i32, i32)],
582            map_slice: &mut Slice<i32, i32>,
583            sub_slice: &mut Slice<i32, i32>,
584        ) {
585            assert_eq!(map_slice, sub_slice);
586            itertools::assert_equal(
587                vec_slice.iter().copied(),
588                map_slice.iter_mut().map(|(&k, &mut v)| (k, v)),
589            );
590            itertools::assert_equal(
591                vec_slice.iter().map(|&(_, v)| v),
592                map_slice.values_mut().map(|&mut v| v),
593            );
594        }
595
596        let vec: Vec<(i32, i32)> = (0..10).map(|i| (i, i * i)).collect();
597        let mut map: IndexMap<i32, i32> = vec.iter().cloned().collect();
598        let mut map2 = map.clone();
599        let slice = map2.as_mut_slice();
600
601        // RangeFull
602        check_mut(&vec[..], &mut map[..], &mut slice[..]);
603
604        for i in 0usize..10 {
605            // IndexMut
606            assert_eq!(&mut map[i], &mut slice[i]);
607
608            // RangeFrom
609            check_mut(&vec[i..], &mut map[i..], &mut slice[i..]);
610
611            // RangeTo
612            check_mut(&vec[..i], &mut map[..i], &mut slice[..i]);
613
614            // RangeToInclusive
615            check_mut(&vec[..=i], &mut map[..=i], &mut slice[..=i]);
616
617            // (Bound<usize>, Bound<usize>)
618            let bounds = (Bound::Excluded(i), Bound::Unbounded);
619            check_mut(&vec[i + 1..], &mut map[bounds], &mut slice[bounds]);
620
621            for j in i..=10 {
622                // Range
623                check_mut(&vec[i..j], &mut map[i..j], &mut slice[i..j]);
624            }
625
626            for j in i..10 {
627                // RangeInclusive
628                check_mut(&vec[i..=j], &mut map[i..=j], &mut slice[i..=j]);
629            }
630        }
631    }
632
633    #[test]
634    fn slice_new() {
635        let slice: &Slice<i32, i32> = Slice::new();
636        assert!(slice.is_empty());
637        assert_eq!(slice.len(), 0);
638    }
639
640    #[test]
641    fn slice_new_mut() {
642        let slice: &mut Slice<i32, i32> = Slice::new_mut();
643        assert!(slice.is_empty());
644        assert_eq!(slice.len(), 0);
645    }
646
647    #[test]
648    fn slice_get_index_mut() {
649        let mut map: IndexMap<i32, i32> = (0..10).map(|i| (i, i * i)).collect();
650        let slice: &mut Slice<i32, i32> = map.as_mut_slice();
651
652        {
653            let (key, value) = slice.get_index_mut(0).unwrap();
654            assert_eq!(*key, 0);
655            assert_eq!(*value, 0);
656
657            *value = 11;
658        }
659
660        assert_eq!(slice[0], 11);
661
662        {
663            let result = slice.get_index_mut(11);
664            assert!(result.is_none());
665        }
666    }
667
668    #[test]
669    fn slice_split_first() {
670        let slice: &mut Slice<i32, i32> = Slice::new_mut();
671        let result = slice.split_first();
672        assert!(result.is_none());
673
674        let mut map: IndexMap<i32, i32> = (0..10).map(|i| (i, i * i)).collect();
675        let slice: &mut Slice<i32, i32> = map.as_mut_slice();
676
677        {
678            let (first, rest) = slice.split_first().unwrap();
679            assert_eq!(first, (&0, &0));
680            assert_eq!(rest.len(), 9);
681        }
682        assert_eq!(slice.len(), 10);
683    }
684
685    #[test]
686    fn slice_split_first_mut() {
687        let slice: &mut Slice<i32, i32> = Slice::new_mut();
688        let result = slice.split_first_mut();
689        assert!(result.is_none());
690
691        let mut map: IndexMap<i32, i32> = (0..10).map(|i| (i, i * i)).collect();
692        let slice: &mut Slice<i32, i32> = map.as_mut_slice();
693
694        {
695            let (first, rest) = slice.split_first_mut().unwrap();
696            assert_eq!(first, (&0, &mut 0));
697            assert_eq!(rest.len(), 9);
698
699            *first.1 = 11;
700        }
701        assert_eq!(slice.len(), 10);
702        assert_eq!(slice[0], 11);
703    }
704
705    #[test]
706    fn slice_split_last() {
707        let slice: &mut Slice<i32, i32> = Slice::new_mut();
708        let result = slice.split_last();
709        assert!(result.is_none());
710
711        let mut map: IndexMap<i32, i32> = (0..10).map(|i| (i, i * i)).collect();
712        let slice: &mut Slice<i32, i32> = map.as_mut_slice();
713
714        {
715            let (last, rest) = slice.split_last().unwrap();
716            assert_eq!(last, (&9, &81));
717            assert_eq!(rest.len(), 9);
718        }
719        assert_eq!(slice.len(), 10);
720    }
721
722    #[test]
723    fn slice_split_last_mut() {
724        let slice: &mut Slice<i32, i32> = Slice::new_mut();
725        let result = slice.split_last_mut();
726        assert!(result.is_none());
727
728        let mut map: IndexMap<i32, i32> = (0..10).map(|i| (i, i * i)).collect();
729        let slice: &mut Slice<i32, i32> = map.as_mut_slice();
730
731        {
732            let (last, rest) = slice.split_last_mut().unwrap();
733            assert_eq!(last, (&9, &mut 81));
734            assert_eq!(rest.len(), 9);
735
736            *last.1 = 100;
737        }
738
739        assert_eq!(slice.len(), 10);
740        assert_eq!(slice[slice.len() - 1], 100);
741    }
742
743    #[test]
744    fn slice_get_range() {
745        let mut map: IndexMap<i32, i32> = (0..10).map(|i| (i, i * i)).collect();
746        let slice: &mut Slice<i32, i32> = map.as_mut_slice();
747        let subslice = slice.get_range(3..6).unwrap();
748        assert_eq!(subslice.len(), 3);
749        assert_eq!(subslice, &[(3, 9), (4, 16), (5, 25)]);
750    }
751}
indexmap/map/slice.rs

indexmap/map/
slice.rs
