map.rs source code [crates/hashbrown-0.14.5/src/map.rs]

1	use crate::raw::{
2	Allocator, Bucket, Global, RawDrain, RawExtractIf, RawIntoIter, RawIter, RawTable,
3	};
4	use crate::{Equivalent, TryReserveError};
5	use core::borrow::Borrow;
6	use core::fmt::{self, Debug};
7	use core::hash::{BuildHasher, Hash};
8	use core::iter::FusedIterator;
9	use core::marker::PhantomData;
10	use core::mem;
11	use core::ops::Index;
12
13	/// Default hasher for `HashMap`.
14	#[cfg(feature = "ahash")]
15	pub type DefaultHashBuilder = core::hash::BuildHasherDefault<ahash::AHasher>;
16
17	/// Dummy default hasher for `HashMap`.
18	#[cfg(not(feature = "ahash"))]
19	pub enum DefaultHashBuilder {}
20
21	/// A hash map implemented with quadratic probing and SIMD lookup.
22	///
23	/// The default hashing algorithm is currently [`AHash`], though this is
24	/// subject to change at any point in the future. This hash function is very
25	/// fast for all types of keys, but this algorithm will typically not* protect*
26	/// against attacks such as HashDoS.
27	///
28	/// The hashing algorithm can be replaced on a per-`HashMap` basis using the
29	/// [`default`], [`with_hasher`], and [`with_capacity_and_hasher`] methods. Many
30	/// alternative algorithms are available on crates.io, such as the [`fnv`] crate.
31	///
32	/// It is required that the keys implement the [`Eq`] and [`Hash`] traits, although
33	/// this can frequently be achieved by using `#[derive(PartialEq, Eq, Hash)]`.
34	/// If you implement these yourself, it is important that the following
35	/// property holds:
36	///
37	/// ```text
38	/// k1 == k2 -> hash(k1) == hash(k2)
39	/// ```
40	///
41	/// In other words, if two keys are equal, their hashes must be equal.
42	///
43	/// It is a logic error for a key to be modified in such a way that the key's
44	/// hash, as determined by the [`Hash`] trait, or its equality, as determined by
45	/// the [`Eq`] trait, changes while it is in the map. This is normally only
46	/// possible through [`Cell`], [`RefCell`], global state, I/O, or unsafe code.
47	///
48	/// It is also a logic error for the [`Hash`] implementation of a key to panic.
49	/// This is generally only possible if the trait is implemented manually. If a
50	/// panic does occur then the contents of the `HashMap` may become corrupted and
51	/// some items may be dropped from the table.
52	///
53	/// # Examples
54	///
55	/// ```
56	/// use hashbrown::HashMap;
57	///
58	/// // Type inference lets us omit an explicit type signature (which
59	/// // would be `HashMap<String, String>` in this example).
60	/// let mut book_reviews = HashMap::new();
61	///
62	/// // Review some books.
63	/// book_reviews.insert(
64	/// "Adventures of Huckleberry Finn".to_string(),
65	/// "My favorite book.".to_string(),
66	/// );
67	/// book_reviews.insert(
68	/// "Grimms' Fairy Tales".to_string(),
69	/// "Masterpiece.".to_string(),
70	/// );
71	/// book_reviews.insert(
72	/// "Pride and Prejudice".to_string(),
73	/// "Very enjoyable.".to_string(),
74	/// );
75	/// book_reviews.insert(
76	/// "The Adventures of Sherlock Holmes".to_string(),
77	/// "Eye lyked it alot.".to_string(),
78	/// );
79	///
80	/// // Check for a specific one.
81	/// // When collections store owned values (String), they can still be
82	/// // queried using references (&str).
83	/// if !book_reviews.contains_key("Les Misérables") {
84	/// println!("We've got {} reviews, but Les Misérables ain't one.",
85	/// book_reviews.len());
86	/// }
87	///
88	/// // oops, this review has a lot of spelling mistakes, let's delete it.
89	/// book_reviews.remove("The Adventures of Sherlock Holmes");
90	///
91	/// // Look up the values associated with some keys.
92	/// let to_find = ["Pride and Prejudice", "Alice's Adventure in Wonderland"];
93	/// for &book in &to_find {
94	/// match book_reviews.get(book) {
95	/// Some(review) => println!("{}: {}", book, review),
96	/// None => println!("{} is unreviewed.", book)
97	/// }
98	/// }
99	///
100	/// // Look up the value for a key (will panic if the key is not found).
101	/// println!("Review for Jane: {}", book_reviews["Pride and Prejudice"]);
102	///
103	/// // Iterate over everything.
104	/// for (book, review) in &book_reviews {
105	/// println!("{}: `\"`{}`\"`", book, review);
106	/// }
107	/// ```
108	///
109	/// `HashMap` also implements an [`Entry API`](#method.entry), which allows
110	/// for more complex methods of getting, setting, updating and removing keys and
111	/// their values:
112	///
113	/// ```
114	/// use hashbrown::HashMap;
115	///
116	/// // type inference lets us omit an explicit type signature (which
117	/// // would be `HashMap<&str, u8>` in this example).
118	/// let mut player_stats = HashMap::new();
119	///
120	/// fn random_stat_buff() -> u8 {
121	/// // could actually return some random value here - let's just return
122	/// // some fixed value for now
123	/// `42`
124	/// }
125	///
126	/// // insert a key only if it doesn't already exist
127	/// player_stats.entry("health").or_insert(`100`);
128	///
129	/// // insert a key using a function that provides a new value only if it
130	/// // doesn't already exist
131	/// player_stats.entry("defence").or_insert_with(random_stat_buff);
132	///
133	/// // update a key, guarding against the key possibly not being set
134	/// let stat = player_stats.entry("attack").or_insert(`100`);
135	/// *stat += random_stat_buff();
136	/// ```
137	///
138	/// The easiest way to use `HashMap` with a custom key type is to derive [`Eq`] and [`Hash`].
139	/// We must also derive [`PartialEq`].
140	///
141	/// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
142	/// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
143	/// [`PartialEq`]: https://doc.rust-lang.org/std/cmp/trait.PartialEq.html
144	/// [`RefCell`]: https://doc.rust-lang.org/std/cell/struct.RefCell.html
145	/// [`Cell`]: https://doc.rust-lang.org/std/cell/struct.Cell.html
146	/// [`default`]: #method.default
147	/// [`with_hasher`]: #method.with_hasher
148	/// [`with_capacity_and_hasher`]: #method.with_capacity_and_hasher
149	/// [`fnv`]: https://crates.io/crates/fnv
150	/// [`AHash`]: https://crates.io/crates/ahash
151	///
152	/// ```
153	/// use hashbrown::HashMap;
154	///
155	/// #[derive(Hash, Eq, PartialEq, Debug)]
156	/// struct Viking {
157	/// name: String,
158	/// country: String,
159	/// }
160	///
161	/// impl Viking {
162	/// /// Creates a new Viking.
163	/// fn new(name: &str, country: &str) -> Viking {
164	/// Viking { name: name.to_string(), country: country.to_string() }
165	/// }
166	/// }
167	///
168	/// // Use a HashMap to store the vikings' health points.
169	/// let mut vikings = HashMap::new();
170	///
171	/// vikings.insert(Viking::new("Einar", "Norway"), `25`);
172	/// vikings.insert(Viking::new("Olaf", "Denmark"), `24`);
173	/// vikings.insert(Viking::new("Harald", "Iceland"), `12`);
174	///
175	/// // Use derived implementation to print the status of the vikings.
176	/// for (viking, health) in &vikings {
177	/// println!("{:?} has {} hp", viking, health);
178	/// }
179	/// ```
180	///
181	/// A `HashMap` with fixed list of elements can be initialized from an array:
182	///
183	/// ```
184	/// use hashbrown::HashMap;
185	///
186	/// let timber_resources: HashMap<&str, i32> = [("Norway", `100`), ("Denmark", `50`), ("Iceland", `10`)]
187	/// .into_iter().collect();
188	/// // use the values stored in map
189	/// ```
190	pub struct HashMap<K, V, S = DefaultHashBuilder, A: Allocator = Global> {
191	pub(crate) hash_builder: S,
192	pub(crate) table: RawTable<(K, V), A>,
193	}
194
195	impl<K: Clone, V: Clone, S: Clone, A: Allocator + Clone> Clone for HashMap<K, V, S, A> {
196	fn clone(&self) -> Self {
197	HashMap {
198	hash_builder: self.hash_builder.clone(),
199	table: self.table.clone(),
200	}
201	}
202
203	fn clone_from(&mut self, source: &Self) {
204	self.table.clone_from(&source.table);
205
206	// Update hash_builder only if we successfully cloned all elements.
207	self.hash_builder.clone_from(&source.hash_builder);
208	}
209	}
210
211	/// Ensures that a single closure type across uses of this which, in turn prevents multiple
212	/// instances of any functions like RawTable::reserve from being generated
213	#[cfg_attr(feature = "inline-more", inline)]
214	pub(crate) fn make_hasher<Q, V, S>(hash_builder: &S) -> impl Fn(&(Q, V)) -> u64 + '_
215	where
216	Q: Hash,
217	S: BuildHasher,
218	{
219	move \|val: &(Q, V)\| make_hash::<Q, S>(hash_builder, &val.0)
220	}
221
222	/// Ensures that a single closure type across uses of this which, in turn prevents multiple
223	/// instances of any functions like RawTable::reserve from being generated
224	#[cfg_attr(feature = "inline-more", inline)]
225	fn equivalent_key<Q, K, V>(k: &Q) -> impl Fn(&(K, V)) -> bool + '_
226	where
227	Q: ?Sized + Equivalent<K>,
228	{
229	move \|x: &(K, V)\| k.equivalent(&x.0)
230	}
231
232	/// Ensures that a single closure type across uses of this which, in turn prevents multiple
233	/// instances of any functions like RawTable::reserve from being generated
234	#[cfg_attr(feature = "inline-more", inline)]
235	fn equivalent<Q, K>(k: &Q) -> impl Fn(&K) -> bool + '_
236	where
237	Q: ?Sized + Equivalent<K>,
238	{
239	move \|x: &K\| k.equivalent(key:x)
240	}
241
242	#[cfg(not(feature = "nightly"))]
243	#[cfg_attr(feature = "inline-more", inline)]
244	pub(crate) fn make_hash<Q, S>(hash_builder: &S, val: &Q) -> u64
245	where
246	Q: Hash + ?Sized,
247	S: BuildHasher,
248	{
249	use core::hash::Hasher;
250	let mut state: ~~::Hasher~~ ~~= hash_builder.build_hasher();~~
251	val.hash(&mut state);
252	state.finish()
253	}
254
255	#[cfg(feature = "nightly")]
256	#[cfg_attr(feature = "inline-more", inline)]
257	pub(crate) fn make_hash<Q, S>(hash_builder: &S, val: &Q) -> u64
258	where
259	Q: Hash + ?Sized,
260	S: BuildHasher,
261	{
262	hash_builder.hash_one(val)
263	}
264
265	#[cfg(feature = "ahash")]
266	impl<K, V> HashMap<K, V, DefaultHashBuilder> {
267	/// Creates an empty `HashMap`.
268	///
269	/// The hash map is initially created with a capacity of 0, so it will not allocate until it
270	/// is first inserted into.
271	///
272	/// # HashDoS resistance
273	///
274	/// The `hash_builder` normally use a fixed key by default and that does
275	/// not allow the `HashMap` to be protected against attacks such as [`HashDoS`].
276	/// Users who require HashDoS resistance should explicitly use
277	/// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
278	/// as the hasher when creating a [`HashMap`], for example with
279	/// [`with_hasher`](HashMap::with_hasher) method.
280	///
281	/// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
282	/// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
283	///
284	/// # Examples
285	///
286	/// ```
287	/// use hashbrown::HashMap;
288	/// let mut map: HashMap<&str, i32> = HashMap::new();
289	/// assert_eq!(map.len(), 0);
290	/// assert_eq!(map.capacity(), 0);
291	/// ```
292	#[cfg_attr(feature = "inline-more", inline)]
293	pub fn new() -> Self {
294	Self::default()
295	}
296
297	/// Creates an empty `HashMap` with the specified capacity.
298	///
299	/// The hash map will be able to hold at least `capacity` elements without
300	/// reallocating. If `capacity` is 0, the hash map will not allocate.
301	///
302	/// # HashDoS resistance
303	///
304	/// The `hash_builder` normally use a fixed key by default and that does
305	/// not allow the `HashMap` to be protected against attacks such as [`HashDoS`].
306	/// Users who require HashDoS resistance should explicitly use
307	/// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
308	/// as the hasher when creating a [`HashMap`], for example with
309	/// [`with_capacity_and_hasher`](HashMap::with_capacity_and_hasher) method.
310	///
311	/// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
312	/// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
313	///
314	/// # Examples
315	///
316	/// ```
317	/// use hashbrown::HashMap;
318	/// let mut map: HashMap<&str, i32> = HashMap::with_capacity(10);
319	/// assert_eq!(map.len(), 0);
320	/// assert!(map.capacity() >= 10);
321	/// ```
322	#[cfg_attr(feature = "inline-more", inline)]
323	pub fn with_capacity(capacity: usize) -> Self {
324	Self::with_capacity_and_hasher(capacity, DefaultHashBuilder::default())
325	}
326	}
327
328	#[cfg(feature = "ahash")]
329	impl<K, V, A: Allocator> HashMap<K, V, DefaultHashBuilder, A> {
330	/// Creates an empty `HashMap` using the given allocator.
331	///
332	/// The hash map is initially created with a capacity of 0, so it will not allocate until it
333	/// is first inserted into.
334	///
335	/// # HashDoS resistance
336	///
337	/// The `hash_builder` normally use a fixed key by default and that does
338	/// not allow the `HashMap` to be protected against attacks such as [`HashDoS`].
339	/// Users who require HashDoS resistance should explicitly use
340	/// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
341	/// as the hasher when creating a [`HashMap`], for example with
342	/// [`with_hasher_in`](HashMap::with_hasher_in) method.
343	///
344	/// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
345	/// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
346	///
347	/// # Examples
348	///
349	/// ```
350	/// use hashbrown::HashMap;
351	/// use bumpalo::Bump;
352	///
353	/// let bump = Bump::new();
354	/// let mut map = HashMap::new_in(&bump);
355	///
356	/// // The created HashMap holds none elements
357	/// assert_eq!(map.len(), 0);
358	///
359	/// // The created HashMap also doesn't allocate memory
360	/// assert_eq!(map.capacity(), 0);
361	///
362	/// // Now we insert element inside created HashMap
363	/// map.insert("One", 1);
364	/// // We can see that the HashMap holds 1 element
365	/// assert_eq!(map.len(), 1);
366	/// // And it also allocates some capacity
367	/// assert!(map.capacity() > 1);
368	/// ```
369	#[cfg_attr(feature = "inline-more", inline)]
370	pub fn new_in(alloc: A) -> Self {
371	Self::with_hasher_in(DefaultHashBuilder::default(), alloc)
372	}
373
374	/// Creates an empty `HashMap` with the specified capacity using the given allocator.
375	///
376	/// The hash map will be able to hold at least `capacity` elements without
377	/// reallocating. If `capacity` is 0, the hash map will not allocate.
378	///
379	/// # HashDoS resistance
380	///
381	/// The `hash_builder` normally use a fixed key by default and that does
382	/// not allow the `HashMap` to be protected against attacks such as [`HashDoS`].
383	/// Users who require HashDoS resistance should explicitly use
384	/// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
385	/// as the hasher when creating a [`HashMap`], for example with
386	/// [`with_capacity_and_hasher_in`](HashMap::with_capacity_and_hasher_in) method.
387	///
388	/// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
389	/// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
390	///
391	/// # Examples
392	///
393	/// ```
394	/// use hashbrown::HashMap;
395	/// use bumpalo::Bump;
396	///
397	/// let bump = Bump::new();
398	/// let mut map = HashMap::with_capacity_in(5, &bump);
399	///
400	/// // The created HashMap holds none elements
401	/// assert_eq!(map.len(), 0);
402	/// // But it can hold at least 5 elements without reallocating
403	/// let empty_map_capacity = map.capacity();
404	/// assert!(empty_map_capacity >= 5);
405	///
406	/// // Now we insert some 5 elements inside created HashMap
407	/// map.insert("One", 1);
408	/// map.insert("Two", 2);
409	/// map.insert("Three", 3);
410	/// map.insert("Four", 4);
411	/// map.insert("Five", 5);
412	///
413	/// // We can see that the HashMap holds 5 elements
414	/// assert_eq!(map.len(), 5);
415	/// // But its capacity isn't changed
416	/// assert_eq!(map.capacity(), empty_map_capacity)
417	/// ```
418	#[cfg_attr(feature = "inline-more", inline)]
419	pub fn with_capacity_in(capacity: usize, alloc: A) -> Self {
420	Self::with_capacity_and_hasher_in(capacity, DefaultHashBuilder::default(), alloc)
421	}
422	}
423
424	impl<K, V, S> HashMap<K, V, S> {
425	/// Creates an empty `HashMap` which will use the given hash builder to hash
426	/// keys.
427	///
428	/// The hash map is initially created with a capacity of 0, so it will not
429	/// allocate until it is first inserted into.
430	///
431	/// # HashDoS resistance
432	///
433	/// The `hash_builder` normally use a fixed key by default and that does
434	/// not allow the `HashMap` to be protected against attacks such as [`HashDoS`].
435	/// Users who require HashDoS resistance should explicitly use
436	/// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
437	/// as the hasher when creating a [`HashMap`].
438	///
439	/// The `hash_builder` passed should implement the [`BuildHasher`] trait for
440	/// the HashMap to be useful, see its documentation for details.
441	///
442	/// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
443	/// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
444	/// [`BuildHasher`]: https://doc.rust-lang.org/std/hash/trait.BuildHasher.html
445	///
446	/// # Examples
447	///
448	/// ```
449	/// use hashbrown::HashMap;
450	/// use hashbrown::hash_map::DefaultHashBuilder;
451	///
452	/// let s = DefaultHashBuilder::default();
453	/// let mut map = HashMap::with_hasher(s);
454	/// assert_eq!(map.len(), `0`);
455	/// assert_eq!(map.capacity(), `0`);
456	///
457	/// map.insert(`1`, `2`);
458	/// ```
459	#[cfg_attr(feature = "inline-more", inline)]
460	pub const fn with_hasher(hash_builder: S) -> Self {
461	Self {
462	hash_builder,
463	table: RawTable::new(),
464	}
465	}
466
467	/// Creates an empty `HashMap` with the specified capacity, using `hash_builder`
468	/// to hash the keys.
469	///
470	/// The hash map will be able to hold at least `capacity` elements without
471	/// reallocating. If `capacity` is 0, the hash map will not allocate.
472	///
473	/// # HashDoS resistance
474	///
475	/// The `hash_builder` normally use a fixed key by default and that does
476	/// not allow the `HashMap` to be protected against attacks such as [`HashDoS`].
477	/// Users who require HashDoS resistance should explicitly use
478	/// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
479	/// as the hasher when creating a [`HashMap`].
480	///
481	/// The `hash_builder` passed should implement the [`BuildHasher`] trait for
482	/// the HashMap to be useful, see its documentation for details.
483	///
484	/// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
485	/// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
486	/// [`BuildHasher`]: https://doc.rust-lang.org/std/hash/trait.BuildHasher.html
487	///
488	/// # Examples
489	///
490	/// ```
491	/// use hashbrown::HashMap;
492	/// use hashbrown::hash_map::DefaultHashBuilder;
493	///
494	/// let s = DefaultHashBuilder::default();
495	/// let mut map = HashMap::with_capacity_and_hasher(`10`, s);
496	/// assert_eq!(map.len(), `0`);
497	/// assert!(map.capacity() >= `10`);
498	///
499	/// map.insert(`1`, `2`);
500	/// ```
501	#[cfg_attr(feature = "inline-more", inline)]
502	pub fn with_capacity_and_hasher(capacity: usize, hash_builder: S) -> Self {
503	Self {
504	hash_builder,
505	table: RawTable::with_capacity(capacity),
506	}
507	}
508	}
509
510	impl<K, V, S, A: Allocator> HashMap<K, V, S, A> {
511	/// Returns a reference to the underlying allocator.
512	#[inline]
513	pub fn allocator(&self) -> &A {
514	self.table.allocator()
515	}
516
517	/// Creates an empty `HashMap` which will use the given hash builder to hash
518	/// keys. It will be allocated with the given allocator.
519	///
520	/// The hash map is initially created with a capacity of 0, so it will not allocate until it
521	/// is first inserted into.
522	///
523	/// # HashDoS resistance
524	///
525	/// The `hash_builder` normally use a fixed key by default and that does
526	/// not allow the `HashMap` to be protected against attacks such as [`HashDoS`].
527	/// Users who require HashDoS resistance should explicitly use
528	/// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
529	/// as the hasher when creating a [`HashMap`].
530	///
531	/// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
532	/// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
533	///
534	/// # Examples
535	///
536	/// ```
537	/// use hashbrown::HashMap;
538	/// use hashbrown::hash_map::DefaultHashBuilder;
539	///
540	/// let s = DefaultHashBuilder::default();
541	/// let mut map = HashMap::with_hasher(s);
542	/// map.insert(`1`, `2`);
543	/// ```
544	#[cfg_attr(feature = "inline-more", inline)]
545	pub const fn with_hasher_in(hash_builder: S, alloc: A) -> Self {
546	Self {
547	hash_builder,
548	table: RawTable::new_in(alloc),
549	}
550	}
551
552	/// Creates an empty `HashMap` with the specified capacity, using `hash_builder`
553	/// to hash the keys. It will be allocated with the given allocator.
554	///
555	/// The hash map will be able to hold at least `capacity` elements without
556	/// reallocating. If `capacity` is 0, the hash map will not allocate.
557	///
558	/// # HashDoS resistance
559	///
560	/// The `hash_builder` normally use a fixed key by default and that does
561	/// not allow the `HashMap` to be protected against attacks such as [`HashDoS`].
562	/// Users who require HashDoS resistance should explicitly use
563	/// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
564	/// as the hasher when creating a [`HashMap`].
565	///
566	/// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
567	/// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
568	///
569	/// # Examples
570	///
571	/// ```
572	/// use hashbrown::HashMap;
573	/// use hashbrown::hash_map::DefaultHashBuilder;
574	///
575	/// let s = DefaultHashBuilder::default();
576	/// let mut map = HashMap::with_capacity_and_hasher(`10`, s);
577	/// map.insert(`1`, `2`);
578	/// ```
579	#[cfg_attr(feature = "inline-more", inline)]
580	pub fn with_capacity_and_hasher_in(capacity: usize, hash_builder: S, alloc: A) -> Self {
581	Self {
582	hash_builder,
583	table: RawTable::with_capacity_in(capacity, alloc),
584	}
585	}
586
587	/// Returns a reference to the map's [`BuildHasher`].
588	///
589	/// [`BuildHasher`]: https://doc.rust-lang.org/std/hash/trait.BuildHasher.html
590	///
591	/// # Examples
592	///
593	/// ```
594	/// use hashbrown::HashMap;
595	/// use hashbrown::hash_map::DefaultHashBuilder;
596	///
597	/// let hasher = DefaultHashBuilder::default();
598	/// let map: HashMap<i32, i32> = HashMap::with_hasher(hasher);
599	/// let hasher: &DefaultHashBuilder = map.hasher();
600	/// ```
601	#[cfg_attr(feature = "inline-more", inline)]
602	pub fn hasher(&self) -> &S {
603	&self.hash_builder
604	}
605
606	/// Returns the number of elements the map can hold without reallocating.
607	///
608	/// This number is a lower bound; the `HashMap<K, V>` might be able to hold
609	/// more, but is guaranteed to be able to hold at least this many.
610	///
611	/// # Examples
612	///
613	/// ```
614	/// use hashbrown::HashMap;
615	/// let map: HashMap<i32, i32> = HashMap::with_capacity(`100`);
616	/// assert_eq!(map.len(), `0`);
617	/// assert!(map.capacity() >= `100`);
618	/// ```
619	#[cfg_attr(feature = "inline-more", inline)]
620	pub fn capacity(&self) -> usize {
621	self.table.capacity()
622	}
623
624	/// An iterator visiting all keys in arbitrary order.
625	/// The iterator element type is `&'a K`.
626	///
627	/// # Examples
628	///
629	/// ```
630	/// use hashbrown::HashMap;
631	///
632	/// let mut map = HashMap::new();
633	/// map.insert("a", `1`);
634	/// map.insert("b", `2`);
635	/// map.insert("c", `3`);
636	/// assert_eq!(map.len(), `3`);
637	/// let mut vec: Vec<&str> = Vec::new();
638	///
639	/// for key in map.keys() {
640	/// println!("{}", key);
641	/// vec.push(*key);
642	/// }
643	///
644	/// // The `Keys` iterator produces keys in arbitrary order, so the
645	/// // keys must be sorted to test them against a sorted array.
646	/// vec.sort_unstable();
647	/// assert_eq!(vec, ["a", "b", "c"]);
648	///
649	/// assert_eq!(map.len(), `3`);
650	/// ```
651	#[cfg_attr(feature = "inline-more", inline)]
652	pub fn keys(&self) -> Keys<'_, K, V> {
653	Keys { inner: self.iter() }
654	}
655
656	/// An iterator visiting all values in arbitrary order.
657	/// The iterator element type is `&'a V`.
658	///
659	/// # Examples
660	///
661	/// ```
662	/// use hashbrown::HashMap;
663	///
664	/// let mut map = HashMap::new();
665	/// map.insert("a", `1`);
666	/// map.insert("b", `2`);
667	/// map.insert("c", `3`);
668	/// assert_eq!(map.len(), `3`);
669	/// let mut vec: Vec<i32> = Vec::new();
670	///
671	/// for val in map.values() {
672	/// println!("{}", val);
673	/// vec.push(*val);
674	/// }
675	///
676	/// // The `Values` iterator produces values in arbitrary order, so the
677	/// // values must be sorted to test them against a sorted array.
678	/// vec.sort_unstable();
679	/// assert_eq!(vec, [`1`, `2`, `3`]);
680	///
681	/// assert_eq!(map.len(), `3`);
682	/// ```
683	#[cfg_attr(feature = "inline-more", inline)]
684	pub fn values(&self) -> Values<'_, K, V> {
685	Values { inner: self.iter() }
686	}
687
688	/// An iterator visiting all values mutably in arbitrary order.
689	/// The iterator element type is `&'a mut V`.
690	///
691	/// # Examples
692	///
693	/// ```
694	/// use hashbrown::HashMap;
695	///
696	/// let mut map = HashMap::new();
697	///
698	/// map.insert("a", `1`);
699	/// map.insert("b", `2`);
700	/// map.insert("c", `3`);
701	///
702	/// for val in map.values_mut() {
703	/// val = val + `10`;
704	/// }
705	///
706	/// assert_eq!(map.len(), `3`);
707	/// let mut vec: Vec<i32> = Vec::new();
708	///
709	/// for val in map.values() {
710	/// println!("{}", val);
711	/// vec.push(*val);
712	/// }
713	///
714	/// // The `Values` iterator produces values in arbitrary order, so the
715	/// // values must be sorted to test them against a sorted array.
716	/// vec.sort_unstable();
717	/// assert_eq!(vec, [`11`, `12`, `13`]);
718	///
719	/// assert_eq!(map.len(), `3`);
720	/// ```
721	#[cfg_attr(feature = "inline-more", inline)]
722	pub fn values_mut(&mut self) -> ValuesMut<'_, K, V> {
723	ValuesMut {
724	inner: self.iter_mut(),
725	}
726	}
727
728	/// An iterator visiting all key-value pairs in arbitrary order.
729	/// The iterator element type is `(&'a K, &'a V)`.
730	///
731	/// # Examples
732	///
733	/// ```
734	/// use hashbrown::HashMap;
735	///
736	/// let mut map = HashMap::new();
737	/// map.insert("a", `1`);
738	/// map.insert("b", `2`);
739	/// map.insert("c", `3`);
740	/// assert_eq!(map.len(), `3`);
741	/// let mut vec: Vec<(&str, i32)> = Vec::new();
742	///
743	/// for (key, val) in map.iter() {
744	/// println!("key: {} val: {}", key, val);
745	/// vec.push((key, val));
746	/// }
747	///
748	/// // The `Iter` iterator produces items in arbitrary order, so the
749	/// // items must be sorted to test them against a sorted array.
750	/// vec.sort_unstable();
751	/// assert_eq!(vec, [("a", `1`), ("b", `2`), ("c", `3`)]);
752	///
753	/// assert_eq!(map.len(), `3`);
754	/// ```
755	#[cfg_attr(feature = "inline-more", inline)]
756	pub fn iter(&self) -> Iter<'_, K, V> {
757	// Here we tie the lifetime of self to the iter.
758	unsafe {
759	Iter {
760	inner: self.table.iter(),
761	marker: PhantomData,
762	}
763	}
764	}
765
766	/// An iterator visiting all key-value pairs in arbitrary order,
767	/// with mutable references to the values.
768	/// The iterator element type is `(&'a K, &'a mut V)`.
769	///
770	/// # Examples
771	///
772	/// ```
773	/// use hashbrown::HashMap;
774	///
775	/// let mut map = HashMap::new();
776	/// map.insert("a", `1`);
777	/// map.insert("b", `2`);
778	/// map.insert("c", `3`);
779	///
780	/// // Update all values
781	/// for (_, val) in map.iter_mut() {
782	/// val = `2`;
783	/// }
784	///
785	/// assert_eq!(map.len(), `3`);
786	/// let mut vec: Vec<(&str, i32)> = Vec::new();
787	///
788	/// for (key, val) in &map {
789	/// println!("key: {} val: {}", key, val);
790	/// vec.push((key, val));
791	/// }
792	///
793	/// // The `Iter` iterator produces items in arbitrary order, so the
794	/// // items must be sorted to test them against a sorted array.
795	/// vec.sort_unstable();
796	/// assert_eq!(vec, [("a", `2`), ("b", `4`), ("c", `6`)]);
797	///
798	/// assert_eq!(map.len(), `3`);
799	/// ```
800	#[cfg_attr(feature = "inline-more", inline)]
801	pub fn iter_mut(&mut self) -> IterMut<'_, K, V> {
802	// Here we tie the lifetime of self to the iter.
803	unsafe {
804	IterMut {
805	inner: self.table.iter(),
806	marker: PhantomData,
807	}
808	}
809	}
810
811	#[cfg(test)]
812	#[cfg_attr(feature = "inline-more", inline)]
813	fn raw_capacity(&self) -> usize {
814	self.table.buckets()
815	}
816
817	/// Returns the number of elements in the map.
818	///
819	/// # Examples
820	///
821	/// ```
822	/// use hashbrown::HashMap;
823	///
824	/// let mut a = HashMap::new();
825	/// assert_eq!(a.len(), `0`);
826	/// a.insert(`1`, "a");
827	/// assert_eq!(a.len(), `1`);
828	/// ```
829	#[cfg_attr(feature = "inline-more", inline)]
830	pub fn len(&self) -> usize {
831	self.table.len()
832	}
833
834	/// Returns `true` if the map contains no elements.
835	///
836	/// # Examples
837	///
838	/// ```
839	/// use hashbrown::HashMap;
840	///
841	/// let mut a = HashMap::new();
842	/// assert!(a.is_empty());
843	/// a.insert(`1`, "a");
844	/// assert!(!a.is_empty());
845	/// ```
846	#[cfg_attr(feature = "inline-more", inline)]
847	pub fn is_empty(&self) -> bool {
848	self.len() == `0`
849	}
850
851	/// Clears the map, returning all key-value pairs as an iterator. Keeps the
852	/// allocated memory for reuse.
853	///
854	/// If the returned iterator is dropped before being fully consumed, it
855	/// drops the remaining key-value pairs. The returned iterator keeps a
856	/// mutable borrow on the vector to optimize its implementation.
857	///
858	/// # Examples
859	///
860	/// ```
861	/// use hashbrown::HashMap;
862	///
863	/// let mut a = HashMap::new();
864	/// a.insert(`1`, "a");
865	/// a.insert(`2`, "b");
866	/// let capacity_before_drain = a.capacity();
867	///
868	/// for (k, v) in a.drain().take(`1`) {
869	/// assert!(k == `1` \|\| k == `2`);
870	/// assert!(v == "a" \|\| v == "b");
871	/// }
872	///
873	/// // As we can see, the map is empty and contains no element.
874	/// assert!(a.is_empty() && a.len() == `0`);
875	/// // But map capacity is equal to old one.
876	/// assert_eq!(a.capacity(), capacity_before_drain);
877	///
878	/// let mut a = HashMap::new();
879	/// a.insert(`1`, "a");
880	/// a.insert(`2`, "b");
881	///
882	/// { // Iterator is dropped without being consumed.
883	/// let d = a.drain();
884	/// }
885	///
886	/// // But the map is empty even if we do not use Drain iterator.
887	/// assert!(a.is_empty());
888	/// ```
889	#[cfg_attr(feature = "inline-more", inline)]
890	pub fn drain(&mut self) -> Drain<'_, K, V, A> {
891	Drain {
892	inner: self.table.drain(),
893	}
894	}
895
896	/// Retains only the elements specified by the predicate. Keeps the
897	/// allocated memory for reuse.
898	///
899	/// In other words, remove all pairs `(k, v)` such that `f(&k, &mut v)` returns `false`.
900	/// The elements are visited in unsorted (and unspecified) order.
901	///
902	/// # Examples
903	///
904	/// ```
905	/// use hashbrown::HashMap;
906	///
907	/// let mut map: HashMap<i32, i32> = (`0`..`8`).map(\|x\|(x, x*`10`)).collect();
908	/// assert_eq!(map.len(), `8`);
909	///
910	/// map.retain(\|&k, _\| k % `2` == `0`);
911	///
912	/// // We can see, that the number of elements inside map is changed.
913	/// assert_eq!(map.len(), `4`);
914	///
915	/// let mut vec: Vec<(i32, i32)> = map.iter().map(\|(&k, &v)\| (k, v)).collect();
916	/// vec.sort_unstable();
917	/// assert_eq!(vec, [(`0`, `0`), (`2`, `20`), (`4`, `40`), (`6`, `60`)]);
918	/// ```
919	pub fn retain<F>(&mut self, mut f: F)
920	where
921	F: FnMut(&K, &mut V) -> bool,
922	{
923	// Here we only use `iter` as a temporary, preventing use-after-free
924	unsafe {
925	for item in self.table.iter() {
926	let &mut (ref key, ref mut value) = item.as_mut();
927	if !f(key, value) {
928	self.table.erase(item);
929	}
930	}
931	}
932	}
933
934	/// Drains elements which are true under the given predicate,
935	/// and returns an iterator over the removed items.
936	///
937	/// In other words, move all pairs `(k, v)` such that `f(&k, &mut v)` returns `true` out
938	/// into another iterator.
939	///
940	/// Note that `extract_if` lets you mutate every value in the filter closure, regardless of
941	/// whether you choose to keep or remove it.
942	///
943	/// If the returned `ExtractIf` is not exhausted, e.g. because it is dropped without iterating
944	/// or the iteration short-circuits, then the remaining elements will be retained.
945	/// Use [`retain()`] with a negated predicate if you do not need the returned iterator.
946	///
947	/// Keeps the allocated memory for reuse.
948	///
949	/// [`retain()`]: HashMap::retain
950	///
951	/// # Examples
952	///
953	/// ```
954	/// use hashbrown::HashMap;
955	///
956	/// let mut map: HashMap<i32, i32> = (`0`..`8`).map(\|x\| (x, x)).collect();
957	///
958	/// let drained: HashMap<i32, i32> = map.extract_if(\|k, _v\| k % `2` == `0`).collect();
959	///
960	/// let mut evens = drained.keys().cloned().collect::<Vec<_>>();
961	/// let mut odds = map.keys().cloned().collect::<Vec<_>>();
962	/// evens.sort();
963	/// odds.sort();
964	///
965	/// assert_eq!(evens, vec![`0`, `2`, `4`, `6`]);
966	/// assert_eq!(odds, vec![`1`, `3`, `5`, `7`]);
967	///
968	/// let mut map: HashMap<i32, i32> = (`0`..`8`).map(\|x\| (x, x)).collect();
969	///
970	/// { // Iterator is dropped without being consumed.
971	/// let d = map.extract_if(\|k, _v\| k % `2` != `0`);
972	/// }
973	///
974	/// // ExtractIf was not exhausted, therefore no elements were drained.
975	/// assert_eq!(map.len(), `8`);
976	/// ```
977	#[cfg_attr(feature = "inline-more", inline)]
978	pub fn extract_if<F>(&mut self, f: F) -> ExtractIf<'_, K, V, F, A>
979	where
980	F: FnMut(&K, &mut V) -> bool,
981	{
982	ExtractIf {
983	f,
984	inner: RawExtractIf {
985	iter: unsafe { self.table.iter() },
986	table: &mut self.table,
987	},
988	}
989	}
990
991	/// Clears the map, removing all key-value pairs. Keeps the allocated memory
992	/// for reuse.
993	///
994	/// # Examples
995	///
996	/// ```
997	/// use hashbrown::HashMap;
998	///
999	/// let mut a = HashMap::new();
1000	/// a.insert(`1`, "a");
1001	/// let capacity_before_clear = a.capacity();
1002	///
1003	/// a.clear();
1004	///
1005	/// // Map is empty.
1006	/// assert!(a.is_empty());
1007	/// // But map capacity is equal to old one.
1008	/// assert_eq!(a.capacity(), capacity_before_clear);
1009	/// ```
1010	#[cfg_attr(feature = "inline-more", inline)]
1011	pub fn clear(&mut self) {
1012	self.table.clear();
1013	}
1014
1015	/// Creates a consuming iterator visiting all the keys in arbitrary order.
1016	/// The map cannot be used after calling this.
1017	/// The iterator element type is `K`.
1018	///
1019	/// # Examples
1020	///
1021	/// ```
1022	/// use hashbrown::HashMap;
1023	///
1024	/// let mut map = HashMap::new();
1025	/// map.insert("a", `1`);
1026	/// map.insert("b", `2`);
1027	/// map.insert("c", `3`);
1028	///
1029	/// let mut vec: Vec<&str> = map.into_keys().collect();
1030	///
1031	/// // The `IntoKeys` iterator produces keys in arbitrary order, so the
1032	/// // keys must be sorted to test them against a sorted array.
1033	/// vec.sort_unstable();
1034	/// assert_eq!(vec, ["a", "b", "c"]);
1035	/// ```
1036	#[inline]
1037	pub fn into_keys(self) -> IntoKeys<K, V, A> {
1038	IntoKeys {
1039	inner: self.into_iter(),
1040	}
1041	}
1042
1043	/// Creates a consuming iterator visiting all the values in arbitrary order.
1044	/// The map cannot be used after calling this.
1045	/// The iterator element type is `V`.
1046	///
1047	/// # Examples
1048	///
1049	/// ```
1050	/// use hashbrown::HashMap;
1051	///
1052	/// let mut map = HashMap::new();
1053	/// map.insert("a", `1`);
1054	/// map.insert("b", `2`);
1055	/// map.insert("c", `3`);
1056	///
1057	/// let mut vec: Vec<i32> = map.into_values().collect();
1058	///
1059	/// // The `IntoValues` iterator produces values in arbitrary order, so
1060	/// // the values must be sorted to test them against a sorted array.
1061	/// vec.sort_unstable();
1062	/// assert_eq!(vec, [`1`, `2`, `3`]);
1063	/// ```
1064	#[inline]
1065	pub fn into_values(self) -> IntoValues<K, V, A> {
1066	IntoValues {
1067	inner: self.into_iter(),
1068	}
1069	}
1070	}
1071
1072	impl<K, V, S, A> HashMap<K, V, S, A>
1073	where
1074	K: Eq + Hash,
1075	S: BuildHasher,
1076	A: Allocator,
1077	{
1078	/// Reserves capacity for at least `additional` more elements to be inserted
1079	/// in the `HashMap`. The collection may reserve more space to avoid
1080	/// frequent reallocations.
1081	///
1082	/// # Panics
1083	///
1084	/// Panics if the new capacity exceeds [`isize::MAX`] bytes and [`abort`] the program
1085	/// in case of allocation error. Use [`try_reserve`](HashMap::try_reserve) instead
1086	/// if you want to handle memory allocation failure.
1087	///
1088	/// [`isize::MAX`]: https://doc.rust-lang.org/std/primitive.isize.html
1089	/// [`abort`]: https://doc.rust-lang.org/alloc/alloc/fn.handle_alloc_error.html
1090	///
1091	/// # Examples
1092	///
1093	/// ```
1094	/// use hashbrown::HashMap;
1095	/// let mut map: HashMap<&str, i32> = HashMap::new();
1096	/// // Map is empty and doesn't allocate memory
1097	/// assert_eq!(map.capacity(), `0`);
1098	///
1099	/// map.reserve(`10`);
1100	///
1101	/// // And now map can hold at least 10 elements
1102	/// assert!(map.capacity() >= `10`);
1103	/// ```
1104	#[cfg_attr(feature = "inline-more", inline)]
1105	pub fn reserve(&mut self, additional: usize) {
1106	self.table
1107	.reserve(additional, make_hasher::<_, V, S>(&self.hash_builder));
1108	}
1109
1110	/// Tries to reserve capacity for at least `additional` more elements to be inserted
1111	/// in the given `HashMap<K,V>`. The collection may reserve more space to avoid
1112	/// frequent reallocations.
1113	///
1114	/// # Errors
1115	///
1116	/// If the capacity overflows, or the allocator reports a failure, then an error
1117	/// is returned.
1118	///
1119	/// # Examples
1120	///
1121	/// ```
1122	/// use hashbrown::HashMap;
1123	///
1124	/// let mut map: HashMap<&str, isize> = HashMap::new();
1125	/// // Map is empty and doesn't allocate memory
1126	/// assert_eq!(map.capacity(), `0`);
1127	///
1128	/// map.try_reserve(`10`).expect("why is the test harness OOMing on 10 bytes?");
1129	///
1130	/// // And now map can hold at least 10 elements
1131	/// assert!(map.capacity() >= `10`);
1132	/// ```
1133	/// If the capacity overflows, or the allocator reports a failure, then an error
1134	/// is returned:
1135	/// ```
1136	/// # fn test() {
1137	/// use hashbrown::HashMap;
1138	/// use hashbrown::TryReserveError;
1139	/// let mut map: HashMap<i32, i32> = HashMap::new();
1140	///
1141	/// match map.try_reserve(usize::MAX) {
1142	/// Err(error) => match error {
1143	/// TryReserveError::CapacityOverflow => {}
1144	/// _ => panic!("TryReserveError::AllocError ?"),
1145	/// },
1146	/// _ => panic!(),
1147	/// }
1148	/// # }
1149	/// # fn main() {
1150	/// # #[cfg(not(miri))]
1151	/// # test()
1152	/// # }
1153	/// ```
1154	#[cfg_attr(feature = "inline-more", inline)]
1155	pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError> {
1156	self.table
1157	.try_reserve(additional, make_hasher::<_, V, S>(&self.hash_builder))
1158	}
1159
1160	/// Shrinks the capacity of the map as much as possible. It will drop
1161	/// down as much as possible while maintaining the internal rules
1162	/// and possibly leaving some space in accordance with the resize policy.
1163	///
1164	/// # Examples
1165	///
1166	/// ```
1167	/// use hashbrown::HashMap;
1168	///
1169	/// let mut map: HashMap<i32, i32> = HashMap::with_capacity(`100`);
1170	/// map.insert(`1`, `2`);
1171	/// map.insert(`3`, `4`);
1172	/// assert!(map.capacity() >= `100`);
1173	/// map.shrink_to_fit();
1174	/// assert!(map.capacity() >= `2`);
1175	/// ```
1176	#[cfg_attr(feature = "inline-more", inline)]
1177	pub fn shrink_to_fit(&mut self) {
1178	self.table
1179	.shrink_to(`0`, make_hasher::<_, V, S>(&self.hash_builder));
1180	}
1181
1182	/// Shrinks the capacity of the map with a lower limit. It will drop
1183	/// down no lower than the supplied limit while maintaining the internal rules
1184	/// and possibly leaving some space in accordance with the resize policy.
1185	///
1186	/// This function does nothing if the current capacity is smaller than the
1187	/// supplied minimum capacity.
1188	///
1189	/// # Examples
1190	///
1191	/// ```
1192	/// use hashbrown::HashMap;
1193	///
1194	/// let mut map: HashMap<i32, i32> = HashMap::with_capacity(`100`);
1195	/// map.insert(`1`, `2`);
1196	/// map.insert(`3`, `4`);
1197	/// assert!(map.capacity() >= `100`);
1198	/// map.shrink_to(`10`);
1199	/// assert!(map.capacity() >= `10`);
1200	/// map.shrink_to(`0`);
1201	/// assert!(map.capacity() >= `2`);
1202	/// map.shrink_to(`10`);
1203	/// assert!(map.capacity() >= `2`);
1204	/// ```
1205	#[cfg_attr(feature = "inline-more", inline)]
1206	pub fn shrink_to(&mut self, min_capacity: usize) {
1207	self.table
1208	.shrink_to(min_capacity, make_hasher::<_, V, S>(&self.hash_builder));
1209	}
1210
1211	/// Gets the given key's corresponding entry in the map for in-place manipulation.
1212	///
1213	/// # Examples
1214	///
1215	/// ```
1216	/// use hashbrown::HashMap;
1217	///
1218	/// let mut letters = HashMap::new();
1219	///
1220	/// for ch in "a short treatise on fungi".chars() {
1221	/// let counter = letters.entry(ch).or_insert(`0`);
1222	/// *counter += `1`;
1223	/// }
1224	///
1225	/// assert_eq!(letters[&'s'], `2`);
1226	/// assert_eq!(letters[&'t'], `3`);
1227	/// assert_eq!(letters[&'u'], `1`);
1228	/// assert_eq!(letters.get(&'y'), None);
1229	/// ```
1230	#[cfg_attr(feature = "inline-more", inline)]
1231	pub fn entry(&mut self, key: K) -> Entry<'_, K, V, S, A> {
1232	let hash = make_hash::<K, S>(&self.hash_builder, &key);
1233	if let Some(elem) = self.table.find(hash, equivalent_key(&key)) {
1234	Entry::Occupied(OccupiedEntry {
1235	hash,
1236	key: Some(key),
1237	elem,
1238	table: self,
1239	})
1240	} else {
1241	Entry::Vacant(VacantEntry {
1242	hash,
1243	key,
1244	table: self,
1245	})
1246	}
1247	}
1248
1249	/// Gets the given key's corresponding entry by reference in the map for in-place manipulation.
1250	///
1251	/// # Examples
1252	///
1253	/// ```
1254	/// use hashbrown::HashMap;
1255	///
1256	/// let mut words: HashMap<String, usize> = HashMap::new();
1257	/// let source = ["poneyland", "horseyland", "poneyland", "poneyland"];
1258	/// for (i, &s) in source.iter().enumerate() {
1259	/// let counter = words.entry_ref(s).or_insert(`0`);
1260	/// *counter += `1`;
1261	/// }
1262	///
1263	/// assert_eq!(words["poneyland"], `3`);
1264	/// assert_eq!(words["horseyland"], `1`);
1265	/// ```
1266	#[cfg_attr(feature = "inline-more", inline)]
1267	pub fn entry_ref<'a, 'b, Q: ?Sized>(&'a mut self, key: &'b Q) -> EntryRef<'a, 'b, K, Q, V, S, A>
1268	where
1269	Q: Hash + Equivalent<K>,
1270	{
1271	let hash = make_hash::<Q, S>(&self.hash_builder, key);
1272	if let Some(elem) = self.table.find(hash, equivalent_key(key)) {
1273	EntryRef::Occupied(OccupiedEntryRef {
1274	hash,
1275	key: Some(KeyOrRef::Borrowed(key)),
1276	elem,
1277	table: self,
1278	})
1279	} else {
1280	EntryRef::Vacant(VacantEntryRef {
1281	hash,
1282	key: KeyOrRef::Borrowed(key),
1283	table: self,
1284	})
1285	}
1286	}
1287
1288	/// Returns a reference to the value corresponding to the key.
1289	///
1290	/// The key may be any borrowed form of the map's key type, but
1291	/// [`Hash`] and [`Eq`] on the borrowed form must* match those for*
1292	/// the key type.
1293	///
1294	/// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
1295	/// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
1296	///
1297	/// # Examples
1298	///
1299	/// ```
1300	/// use hashbrown::HashMap;
1301	///
1302	/// let mut map = HashMap::new();
1303	/// map.insert(`1`, "a");
1304	/// assert_eq!(map.get(&`1`), Some(&"a"));
1305	/// assert_eq!(map.get(&`2`), None);
1306	/// ```
1307	#[inline]
1308	pub fn get<Q: ?Sized>(&self, k: &Q) -> Option<&V>
1309	where
1310	Q: Hash + Equivalent<K>,
1311	{
1312	// Avoid `Option::map` because it bloats LLVM IR.
1313	match self.get_inner(k) {
1314	Some((_, v)) => Some(v),
1315	None => None,
1316	}
1317	}
1318
1319	/// Returns the key-value pair corresponding to the supplied key.
1320	///
1321	/// The supplied key may be any borrowed form of the map's key type, but
1322	/// [`Hash`] and [`Eq`] on the borrowed form must* match those for*
1323	/// the key type.
1324	///
1325	/// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
1326	/// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
1327	///
1328	/// # Examples
1329	///
1330	/// ```
1331	/// use hashbrown::HashMap;
1332	///
1333	/// let mut map = HashMap::new();
1334	/// map.insert(`1`, "a");
1335	/// assert_eq!(map.get_key_value(&`1`), Some((&`1`, &"a")));
1336	/// assert_eq!(map.get_key_value(&`2`), None);
1337	/// ```
1338	#[inline]
1339	pub fn get_key_value<Q: ?Sized>(&self, k: &Q) -> Option<(&K, &V)>
1340	where
1341	Q: Hash + Equivalent<K>,
1342	{
1343	// Avoid `Option::map` because it bloats LLVM IR.
1344	match self.get_inner(k) {
1345	Some((key, value)) => Some((key, value)),
1346	None => None,
1347	}
1348	}
1349
1350	#[inline]
1351	fn get_inner<Q: ?Sized>(&self, k: &Q) -> Option<&(K, V)>
1352	where
1353	Q: Hash + Equivalent<K>,
1354	{
1355	if self.table.is_empty() {
1356	None
1357	} else {
1358	let hash = make_hash::<Q, S>(&self.hash_builder, k);
1359	self.table.get(hash, equivalent_key(k))
1360	}
1361	}
1362
1363	/// Returns the key-value pair corresponding to the supplied key, with a mutable reference to value.
1364	///
1365	/// The supplied key may be any borrowed form of the map's key type, but
1366	/// [`Hash`] and [`Eq`] on the borrowed form must* match those for*
1367	/// the key type.
1368	///
1369	/// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
1370	/// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
1371	///
1372	/// # Examples
1373	///
1374	/// ```
1375	/// use hashbrown::HashMap;
1376	///
1377	/// let mut map = HashMap::new();
1378	/// map.insert(`1`, "a");
1379	/// let (k, v) = map.get_key_value_mut(&`1`).unwrap();
1380	/// assert_eq!(k, &`1`);
1381	/// assert_eq!(v, &mut "a");
1382	/// *v = "b";
1383	/// assert_eq!(map.get_key_value_mut(&`1`), Some((&`1`, &mut "b")));
1384	/// assert_eq!(map.get_key_value_mut(&`2`), None);
1385	/// ```
1386	#[inline]
1387	pub fn get_key_value_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<(&K, &mut V)>
1388	where
1389	Q: Hash + Equivalent<K>,
1390	{
1391	// Avoid `Option::map` because it bloats LLVM IR.
1392	match self.get_inner_mut(k) {
1393	Some(&mut (ref key, ref mut value)) => Some((key, value)),
1394	None => None,
1395	}
1396	}
1397
1398	/// Returns `true` if the map contains a value for the specified key.
1399	///
1400	/// The key may be any borrowed form of the map's key type, but
1401	/// [`Hash`] and [`Eq`] on the borrowed form must* match those for*
1402	/// the key type.
1403	///
1404	/// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
1405	/// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
1406	///
1407	/// # Examples
1408	///
1409	/// ```
1410	/// use hashbrown::HashMap;
1411	///
1412	/// let mut map = HashMap::new();
1413	/// map.insert(`1`, "a");
1414	/// assert_eq!(map.contains_key(&`1`), `true`);
1415	/// assert_eq!(map.contains_key(&`2`), `false`);
1416	/// ```
1417	#[cfg_attr(feature = "inline-more", inline)]
1418	pub fn contains_key<Q: ?Sized>(&self, k: &Q) -> bool
1419	where
1420	Q: Hash + Equivalent<K>,
1421	{
1422	self.get_inner(k).is_some()
1423	}
1424
1425	/// Returns a mutable reference to the value corresponding to the key.
1426	///
1427	/// The key may be any borrowed form of the map's key type, but
1428	/// [`Hash`] and [`Eq`] on the borrowed form must* match those for*
1429	/// the key type.
1430	///
1431	/// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
1432	/// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
1433	///
1434	/// # Examples
1435	///
1436	/// ```
1437	/// use hashbrown::HashMap;
1438	///
1439	/// let mut map = HashMap::new();
1440	/// map.insert(`1`, "a");
1441	/// if let Some(x) = map.get_mut(&`1`) {
1442	/// *x = "b";
1443	/// }
1444	/// assert_eq!(map[&`1`], "b");
1445	///
1446	/// assert_eq!(map.get_mut(&`2`), None);
1447	/// ```
1448	#[cfg_attr(feature = "inline-more", inline)]
1449	pub fn get_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut V>
1450	where
1451	Q: Hash + Equivalent<K>,
1452	{
1453	// Avoid `Option::map` because it bloats LLVM IR.
1454	match self.get_inner_mut(k) {
1455	Some(&mut (_, ref mut v)) => Some(v),
1456	None => None,
1457	}
1458	}
1459
1460	#[inline]
1461	fn get_inner_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut (K, V)>
1462	where
1463	Q: Hash + Equivalent<K>,
1464	{
1465	if self.table.is_empty() {
1466	None
1467	} else {
1468	let hash = make_hash::<Q, S>(&self.hash_builder, k);
1469	self.table.get_mut(hash, equivalent_key(k))
1470	}
1471	}
1472
1473	/// Attempts to get mutable references to `N` values in the map at once.
1474	///
1475	/// Returns an array of length `N` with the results of each query. For soundness, at most one
1476	/// mutable reference will be returned to any value. `None` will be returned if any of the
1477	/// keys are duplicates or missing.
1478	///
1479	/// # Examples
1480	///
1481	/// ```
1482	/// use hashbrown::HashMap;
1483	///
1484	/// let mut libraries = HashMap::new();
1485	/// libraries.insert("Bodleian Library".to_string(), `1602`);
1486	/// libraries.insert("Athenæum".to_string(), `1807`);
1487	/// libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), `1691`);
1488	/// libraries.insert("Library of Congress".to_string(), `1800`);
1489	///
1490	/// let got = libraries.get_many_mut([
1491	/// "Athenæum",
1492	/// "Library of Congress",
1493	/// ]);
1494	/// assert_eq!(
1495	/// got,
1496	/// Some([
1497	/// &mut `1807`,
1498	/// &mut `1800`,
1499	/// ]),
1500	/// );
1501	///
1502	/// // Missing keys result in None
1503	/// let got = libraries.get_many_mut([
1504	/// "Athenæum",
1505	/// "New York Public Library",
1506	/// ]);
1507	/// assert_eq!(got, None);
1508	///
1509	/// // Duplicate keys result in None
1510	/// let got = libraries.get_many_mut([
1511	/// "Athenæum",
1512	/// "Athenæum",
1513	/// ]);
1514	/// assert_eq!(got, None);
1515	/// ```
1516	pub fn get_many_mut<Q: ?Sized, const N: usize>(&mut self, ks: [&Q; N]) -> Option<[&'_ mut V; N]>
1517	where
1518	Q: Hash + Equivalent<K>,
1519	{
1520	self.get_many_mut_inner(ks).map(\|res\| res.map(\|(_, v)\| v))
1521	}
1522
1523	/// Attempts to get mutable references to `N` values in the map at once, without validating that
1524	/// the values are unique.
1525	///
1526	/// Returns an array of length `N` with the results of each query. `None` will be returned if
1527	/// any of the keys are missing.
1528	///
1529	/// For a safe alternative see [`get_many_mut`](`HashMap::get_many_mut`).
1530	///
1531	/// # Safety
1532	///
1533	/// Calling this method with overlapping keys is [undefined behavior]* even if the resulting*
1534	/// references are not used.
1535	///
1536	/// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
1537	///
1538	/// # Examples
1539	///
1540	/// ```
1541	/// use hashbrown::HashMap;
1542	///
1543	/// let mut libraries = HashMap::new();
1544	/// libraries.insert("Bodleian Library".to_string(), `1602`);
1545	/// libraries.insert("Athenæum".to_string(), `1807`);
1546	/// libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), `1691`);
1547	/// libraries.insert("Library of Congress".to_string(), `1800`);
1548	///
1549	/// let got = libraries.get_many_mut([
1550	/// "Athenæum",
1551	/// "Library of Congress",
1552	/// ]);
1553	/// assert_eq!(
1554	/// got,
1555	/// Some([
1556	/// &mut `1807`,
1557	/// &mut `1800`,
1558	/// ]),
1559	/// );
1560	///
1561	/// // Missing keys result in None
1562	/// let got = libraries.get_many_mut([
1563	/// "Athenæum",
1564	/// "New York Public Library",
1565	/// ]);
1566	/// assert_eq!(got, None);
1567	/// ```
1568	pub unsafe fn get_many_unchecked_mut<Q: ?Sized, const N: usize>(
1569	&mut self,
1570	ks: [&Q; N],
1571	) -> Option<[&'_ mut V; N]>
1572	where
1573	Q: Hash + Equivalent<K>,
1574	{
1575	self.get_many_unchecked_mut_inner(ks)
1576	.map(\|res\| res.map(\|(_, v)\| v))
1577	}
1578
1579	/// Attempts to get mutable references to `N` values in the map at once, with immutable
1580	/// references to the corresponding keys.
1581	///
1582	/// Returns an array of length `N` with the results of each query. For soundness, at most one
1583	/// mutable reference will be returned to any value. `None` will be returned if any of the keys
1584	/// are duplicates or missing.
1585	///
1586	/// # Examples
1587	///
1588	/// ```
1589	/// use hashbrown::HashMap;
1590	///
1591	/// let mut libraries = HashMap::new();
1592	/// libraries.insert("Bodleian Library".to_string(), `1602`);
1593	/// libraries.insert("Athenæum".to_string(), `1807`);
1594	/// libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), `1691`);
1595	/// libraries.insert("Library of Congress".to_string(), `1800`);
1596	///
1597	/// let got = libraries.get_many_key_value_mut([
1598	/// "Bodleian Library",
1599	/// "Herzogin-Anna-Amalia-Bibliothek",
1600	/// ]);
1601	/// assert_eq!(
1602	/// got,
1603	/// Some([
1604	/// (&"Bodleian Library".to_string(), &mut `1602`),
1605	/// (&"Herzogin-Anna-Amalia-Bibliothek".to_string(), &mut `1691`),
1606	/// ]),
1607	/// );
1608	/// // Missing keys result in None
1609	/// let got = libraries.get_many_key_value_mut([
1610	/// "Bodleian Library",
1611	/// "Gewandhaus",
1612	/// ]);
1613	/// assert_eq!(got, None);
1614	///
1615	/// // Duplicate keys result in None
1616	/// let got = libraries.get_many_key_value_mut([
1617	/// "Bodleian Library",
1618	/// "Herzogin-Anna-Amalia-Bibliothek",
1619	/// "Herzogin-Anna-Amalia-Bibliothek",
1620	/// ]);
1621	/// assert_eq!(got, None);
1622	/// ```
1623	pub fn get_many_key_value_mut<Q: ?Sized, const N: usize>(
1624	&mut self,
1625	ks: [&Q; N],
1626	) -> Option<[(&'_ K, &'_ mut V); N]>
1627	where
1628	Q: Hash + Equivalent<K>,
1629	{
1630	self.get_many_mut_inner(ks)
1631	.map(\|res\| res.map(\|(k, v)\| (&*k, v)))
1632	}
1633
1634	/// Attempts to get mutable references to `N` values in the map at once, with immutable
1635	/// references to the corresponding keys, without validating that the values are unique.
1636	///
1637	/// Returns an array of length `N` with the results of each query. `None` will be returned if
1638	/// any of the keys are missing.
1639	///
1640	/// For a safe alternative see [`get_many_key_value_mut`](`HashMap::get_many_key_value_mut`).
1641	///
1642	/// # Safety
1643	///
1644	/// Calling this method with overlapping keys is [undefined behavior]* even if the resulting*
1645	/// references are not used.
1646	///
1647	/// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
1648	///
1649	/// # Examples
1650	///
1651	/// ```
1652	/// use hashbrown::HashMap;
1653	///
1654	/// let mut libraries = HashMap::new();
1655	/// libraries.insert("Bodleian Library".to_string(), `1602`);
1656	/// libraries.insert("Athenæum".to_string(), `1807`);
1657	/// libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), `1691`);
1658	/// libraries.insert("Library of Congress".to_string(), `1800`);
1659	///
1660	/// let got = libraries.get_many_key_value_mut([
1661	/// "Bodleian Library",
1662	/// "Herzogin-Anna-Amalia-Bibliothek",
1663	/// ]);
1664	/// assert_eq!(
1665	/// got,
1666	/// Some([
1667	/// (&"Bodleian Library".to_string(), &mut `1602`),
1668	/// (&"Herzogin-Anna-Amalia-Bibliothek".to_string(), &mut `1691`),
1669	/// ]),
1670	/// );
1671	/// // Missing keys result in None
1672	/// let got = libraries.get_many_key_value_mut([
1673	/// "Bodleian Library",
1674	/// "Gewandhaus",
1675	/// ]);
1676	/// assert_eq!(got, None);
1677	/// ```
1678	pub unsafe fn get_many_key_value_unchecked_mut<Q: ?Sized, const N: usize>(
1679	&mut self,
1680	ks: [&Q; N],
1681	) -> Option<[(&'_ K, &'_ mut V); N]>
1682	where
1683	Q: Hash + Equivalent<K>,
1684	{
1685	self.get_many_unchecked_mut_inner(ks)
1686	.map(\|res\| res.map(\|(k, v)\| (&*k, v)))
1687	}
1688
1689	fn get_many_mut_inner<Q: ?Sized, const N: usize>(
1690	&mut self,
1691	ks: [&Q; N],
1692	) -> Option<[&'_ mut (K, V); N]>
1693	where
1694	Q: Hash + Equivalent<K>,
1695	{
1696	let hashes = self.build_hashes_inner(ks);
1697	self.table
1698	.get_many_mut(hashes, \|i, (k, _)\| ks[i].equivalent(k))
1699	}
1700
1701	unsafe fn get_many_unchecked_mut_inner<Q: ?Sized, const N: usize>(
1702	&mut self,
1703	ks: [&Q; N],
1704	) -> Option<[&'_ mut (K, V); N]>
1705	where
1706	Q: Hash + Equivalent<K>,
1707	{
1708	let hashes = self.build_hashes_inner(ks);
1709	self.table
1710	.get_many_unchecked_mut(hashes, \|i, (k, _)\| ks[i].equivalent(k))
1711	}
1712
1713	fn build_hashes_inner<Q: ?Sized, const N: usize>(&self, ks: [&Q; N]) -> [u64; N]
1714	where
1715	Q: Hash + Equivalent<K>,
1716	{
1717	let mut hashes = [`0_u64`; N];
1718	for i in `0`..N {
1719	hashes[i] = make_hash::<Q, S>(&self.hash_builder, ks[i]);
1720	}
1721	hashes
1722	}
1723
1724	/// Inserts a key-value pair into the map.
1725	///
1726	/// If the map did not have this key present, [`None`] is returned.
1727	///
1728	/// If the map did have this key present, the value is updated, and the old
1729	/// value is returned. The key is not updated, though; this matters for
1730	/// types that can be `==` without being identical. See the [`std::collections`]
1731	/// [module-level documentation] for more.
1732	///
1733	/// [`None`]: https://doc.rust-lang.org/std/option/enum.Option.html#variant.None
1734	/// [`std::collections`]: https://doc.rust-lang.org/std/collections/index.html
1735	/// [module-level documentation]: https://doc.rust-lang.org/std/collections/index.html#insert-and-complex-keys
1736	///
1737	/// # Examples
1738	///
1739	/// ```
1740	/// use hashbrown::HashMap;
1741	///
1742	/// let mut map = HashMap::new();
1743	/// assert_eq!(map.insert(`37`, "a"), None);
1744	/// assert_eq!(map.is_empty(), `false`);
1745	///
1746	/// map.insert(`37`, "b");
1747	/// assert_eq!(map.insert(`37`, "c"), Some("b"));
1748	/// assert_eq!(map[&`37`], "c");
1749	/// ```
1750	#[cfg_attr(feature = "inline-more", inline)]
1751	pub fn insert(&mut self, k: K, v: V) -> Option<V> {
1752	let hash = make_hash::<K, S>(&self.hash_builder, &k);
1753	let hasher = make_hasher::<_, V, S>(&self.hash_builder);
1754	match self
1755	.table
1756	.find_or_find_insert_slot(hash, equivalent_key(&k), hasher)
1757	{
1758	Ok(bucket) => Some(mem::replace(unsafe { &mut bucket.as_mut().1 }, v)),
1759	Err(slot) => {
1760	unsafe {
1761	self.table.insert_in_slot(hash, slot, (k, v));
1762	}
1763	None
1764	}
1765	}
1766	}
1767
1768	/// Insert a key-value pair into the map without checking
1769	/// if the key already exists in the map.
1770	///
1771	/// Returns a reference to the key and value just inserted.
1772	///
1773	/// This operation is safe if a key does not exist in the map.
1774	///
1775	/// However, if a key exists in the map already, the behavior is unspecified:
1776	/// this operation may panic, loop forever, or any following operation with the map
1777	/// may panic, loop forever or return arbitrary result.
1778	///
1779	/// That said, this operation (and following operations) are guaranteed to
1780	/// not violate memory safety.
1781	///
1782	/// This operation is faster than regular insert, because it does not perform
1783	/// lookup before insertion.
1784	///
1785	/// This operation is useful during initial population of the map.
1786	/// For example, when constructing a map from another map, we know
1787	/// that keys are unique.
1788	///
1789	/// # Examples
1790	///
1791	/// ```
1792	/// use hashbrown::HashMap;
1793	///
1794	/// let mut map1 = HashMap::new();
1795	/// assert_eq!(map1.insert(`1`, "a"), None);
1796	/// assert_eq!(map1.insert(`2`, "b"), None);
1797	/// assert_eq!(map1.insert(`3`, "c"), None);
1798	/// assert_eq!(map1.len(), `3`);
1799	///
1800	/// let mut map2 = HashMap::new();
1801	///
1802	/// for (key, value) in map1.into_iter() {
1803	/// map2.insert_unique_unchecked(key, value);
1804	/// }
1805	///
1806	/// let (key, value) = map2.insert_unique_unchecked(`4`, "d");
1807	/// assert_eq!(key, &`4`);
1808	/// assert_eq!(value, &mut "d");
1809	/// *value = "e";
1810	///
1811	/// assert_eq!(map2[&`1`], "a");
1812	/// assert_eq!(map2[&`2`], "b");
1813	/// assert_eq!(map2[&`3`], "c");
1814	/// assert_eq!(map2[&`4`], "e");
1815	/// assert_eq!(map2.len(), `4`);
1816	/// ```
1817	#[cfg_attr(feature = "inline-more", inline)]
1818	pub fn insert_unique_unchecked(&mut self, k: K, v: V) -> (&K, &mut V) {
1819	let hash = make_hash::<K, S>(&self.hash_builder, &k);
1820	let bucket = self
1821	.table
1822	.insert(hash, (k, v), make_hasher::<_, V, S>(&self.hash_builder));
1823	let (k_ref, v_ref) = unsafe { bucket.as_mut() };
1824	(k_ref, v_ref)
1825	}
1826
1827	/// Tries to insert a key-value pair into the map, and returns
1828	/// a mutable reference to the value in the entry.
1829	///
1830	/// # Errors
1831	///
1832	/// If the map already had this key present, nothing is updated, and
1833	/// an error containing the occupied entry and the value is returned.
1834	///
1835	/// # Examples
1836	///
1837	/// Basic usage:
1838	///
1839	/// ```
1840	/// use hashbrown::HashMap;
1841	/// use hashbrown::hash_map::OccupiedError;
1842	///
1843	/// let mut map = HashMap::new();
1844	/// assert_eq!(map.try_insert(`37`, "a").unwrap(), &"a");
1845	///
1846	/// match map.try_insert(`37`, "b") {
1847	/// Err(OccupiedError { entry, value }) => {
1848	/// assert_eq!(entry.key(), &`37`);
1849	/// assert_eq!(entry.get(), &"a");
1850	/// assert_eq!(value, "b");
1851	/// }
1852	/// _ => panic!()
1853	/// }
1854	/// ```
1855	#[cfg_attr(feature = "inline-more", inline)]
1856	pub fn try_insert(
1857	&mut self,
1858	key: K,
1859	value: V,
1860	) -> Result<&mut V, OccupiedError<'_, K, V, S, A>> {
1861	match self.entry(key) {
1862	Entry::Occupied(entry) => Err(OccupiedError { entry, value }),
1863	Entry::Vacant(entry) => Ok(entry.insert(value)),
1864	}
1865	}
1866
1867	/// Removes a key from the map, returning the value at the key if the key
1868	/// was previously in the map. Keeps the allocated memory for reuse.
1869	///
1870	/// The key may be any borrowed form of the map's key type, but
1871	/// [`Hash`] and [`Eq`] on the borrowed form must* match those for*
1872	/// the key type.
1873	///
1874	/// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
1875	/// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
1876	///
1877	/// # Examples
1878	///
1879	/// ```
1880	/// use hashbrown::HashMap;
1881	///
1882	/// let mut map = HashMap::new();
1883	/// // The map is empty
1884	/// assert!(map.is_empty() && map.capacity() == `0`);
1885	///
1886	/// map.insert(`1`, "a");
1887	///
1888	/// assert_eq!(map.remove(&`1`), Some("a"));
1889	/// assert_eq!(map.remove(&`1`), None);
1890	///
1891	/// // Now map holds none elements
1892	/// assert!(map.is_empty());
1893	/// ```
1894	#[cfg_attr(feature = "inline-more", inline)]
1895	pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> Option<V>
1896	where
1897	Q: Hash + Equivalent<K>,
1898	{
1899	// Avoid `Option::map` because it bloats LLVM IR.
1900	match self.remove_entry(k) {
1901	Some((_, v)) => Some(v),
1902	None => None,
1903	}
1904	}
1905
1906	/// Removes a key from the map, returning the stored key and value if the
1907	/// key was previously in the map. Keeps the allocated memory for reuse.
1908	///
1909	/// The key may be any borrowed form of the map's key type, but
1910	/// [`Hash`] and [`Eq`] on the borrowed form must* match those for*
1911	/// the key type.
1912	///
1913	/// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
1914	/// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
1915	///
1916	/// # Examples
1917	///
1918	/// ```
1919	/// use hashbrown::HashMap;
1920	///
1921	/// let mut map = HashMap::new();
1922	/// // The map is empty
1923	/// assert!(map.is_empty() && map.capacity() == `0`);
1924	///
1925	/// map.insert(`1`, "a");
1926	///
1927	/// assert_eq!(map.remove_entry(&`1`), Some((`1`, "a")));
1928	/// assert_eq!(map.remove(&`1`), None);
1929	///
1930	/// // Now map hold none elements
1931	/// assert!(map.is_empty());
1932	/// ```
1933	#[cfg_attr(feature = "inline-more", inline)]
1934	pub fn remove_entry<Q: ?Sized>(&mut self, k: &Q) -> Option<(K, V)>
1935	where
1936	Q: Hash + Equivalent<K>,
1937	{
1938	let hash = make_hash::<Q, S>(&self.hash_builder, k);
1939	self.table.remove_entry(hash, equivalent_key(k))
1940	}
1941	}
1942
1943	impl<K, V, S, A: Allocator> HashMap<K, V, S, A> {
1944	/// Creates a raw entry builder for the HashMap.
1945	///
1946	/// Raw entries provide the lowest level of control for searching and
1947	/// manipulating a map. They must be manually initialized with a hash and
1948	/// then manually searched. After this, insertions into a vacant entry
1949	/// still require an owned key to be provided.
1950	///
1951	/// Raw entries are useful for such exotic situations as:
1952	///
1953	/// Hash memoization*
1954	/// Deferring the creation of an owned key until it is known to be required*
1955	/// Using a search key that doesn't work with the Borrow trait*
1956	/// Using custom comparison logic without newtype wrappers*
1957	///
1958	/// Because raw entries provide much more low-level control, it's much easier
1959	/// to put the HashMap into an inconsistent state which, while memory-safe,
1960	/// will cause the map to produce seemingly random results. Higher-level and
1961	/// more foolproof APIs like `entry` should be preferred when possible.
1962	///
1963	/// In particular, the hash used to initialized the raw entry must still be
1964	/// consistent with the hash of the key that is ultimately stored in the entry.
1965	/// This is because implementations of HashMap may need to recompute hashes
1966	/// when resizing, at which point only the keys are available.
1967	///
1968	/// Raw entries give mutable access to the keys. This must not be used
1969	/// to modify how the key would compare or hash, as the map will not re-evaluate
1970	/// where the key should go, meaning the keys may become "lost" if their
1971	/// location does not reflect their state. For instance, if you change a key
1972	/// so that the map now contains keys which compare equal, search may start
1973	/// acting erratically, with two keys randomly masking each other. Implementations
1974	/// are free to assume this doesn't happen (within the limits of memory-safety).
1975	///
1976	/// # Examples
1977	///
1978	/// ```
1979	/// use core::hash::{BuildHasher, Hash};
1980	/// use hashbrown::hash_map::{HashMap, RawEntryMut};
1981	///
1982	/// let mut map = HashMap::new();
1983	/// map.extend([("a", `100`), ("b", `200`), ("c", `300`)]);
1984	///
1985	/// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
1986	/// use core::hash::Hasher;
1987	/// let mut state = hash_builder.build_hasher();
1988	/// key.hash(&mut state);
1989	/// state.finish()
1990	/// }
1991	///
1992	/// // Existing key (insert and update)
1993	/// match map.raw_entry_mut().from_key(&"a") {
1994	/// RawEntryMut::Vacant(_) => unreachable!(),
1995	/// RawEntryMut::Occupied(mut view) => {
1996	/// assert_eq!(view.get(), &`100`);
1997	/// let v = view.get_mut();
1998	/// let new_v = (v) `10`;
1999	/// *v = new_v;
2000	/// assert_eq!(view.insert(`1111`), `1000`);
2001	/// }
2002	/// }
2003	///
2004	/// assert_eq!(map[&"a"], `1111`);
2005	/// assert_eq!(map.len(), `3`);
2006	///
2007	/// // Existing key (take)
2008	/// let hash = compute_hash(map.hasher(), &"c");
2009	/// match map.raw_entry_mut().from_key_hashed_nocheck(hash, &"c") {
2010	/// RawEntryMut::Vacant(_) => unreachable!(),
2011	/// RawEntryMut::Occupied(view) => {
2012	/// assert_eq!(view.remove_entry(), ("c", `300`));
2013	/// }
2014	/// }
2015	/// assert_eq!(map.raw_entry().from_key(&"c"), None);
2016	/// assert_eq!(map.len(), `2`);
2017	///
2018	/// // Nonexistent key (insert and update)
2019	/// let key = "d";
2020	/// let hash = compute_hash(map.hasher(), &key);
2021	/// match map.raw_entry_mut().from_hash(hash, \|q\| *q == key) {
2022	/// RawEntryMut::Occupied(_) => unreachable!(),
2023	/// RawEntryMut::Vacant(view) => {
2024	/// let (k, value) = view.insert("d", `4000`);
2025	/// assert_eq!((k, value), ("d", `4000`));
2026	/// *value = `40000`;
2027	/// }
2028	/// }
2029	/// assert_eq!(map[&"d"], `40000`);
2030	/// assert_eq!(map.len(), `3`);
2031	///
2032	/// match map.raw_entry_mut().from_hash(hash, \|q\| *q == key) {
2033	/// RawEntryMut::Vacant(_) => unreachable!(),
2034	/// RawEntryMut::Occupied(view) => {
2035	/// assert_eq!(view.remove_entry(), ("d", `40000`));
2036	/// }
2037	/// }
2038	/// assert_eq!(map.get(&"d"), None);
2039	/// assert_eq!(map.len(), `2`);
2040	/// ```
2041	#[cfg_attr(feature = "inline-more", inline)]
2042	pub fn raw_entry_mut(&mut self) -> RawEntryBuilderMut<'_, K, V, S, A> {
2043	RawEntryBuilderMut { map: self }
2044	}
2045
2046	/// Creates a raw immutable entry builder for the HashMap.
2047	///
2048	/// Raw entries provide the lowest level of control for searching and
2049	/// manipulating a map. They must be manually initialized with a hash and
2050	/// then manually searched.
2051	///
2052	/// This is useful for
2053	/// Hash memoization*
2054	/// Using a search key that doesn't work with the Borrow trait*
2055	/// Using custom comparison logic without newtype wrappers*
2056	///
2057	/// Unless you are in such a situation, higher-level and more foolproof APIs like
2058	/// `get` should be preferred.
2059	///
2060	/// Immutable raw entries have very limited use; you might instead want `raw_entry_mut`.
2061	///
2062	/// # Examples
2063	///
2064	/// ```
2065	/// use core::hash::{BuildHasher, Hash};
2066	/// use hashbrown::HashMap;
2067	///
2068	/// let mut map = HashMap::new();
2069	/// map.extend([("a", `100`), ("b", `200`), ("c", `300`)]);
2070	///
2071	/// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
2072	/// use core::hash::Hasher;
2073	/// let mut state = hash_builder.build_hasher();
2074	/// key.hash(&mut state);
2075	/// state.finish()
2076	/// }
2077	///
2078	/// for k in ["a", "b", "c", "d", "e", "f"] {
2079	/// let hash = compute_hash(map.hasher(), k);
2080	/// let v = map.get(&k).cloned();
2081	/// let kv = v.as_ref().map(\|v\| (&k, v));
2082	///
2083	/// println!("Key: {} and value: {:?}", k, v);
2084	///
2085	/// assert_eq!(map.raw_entry().from_key(&k), kv);
2086	/// assert_eq!(map.raw_entry().from_hash(hash, \|q\| *q == k), kv);
2087	/// assert_eq!(map.raw_entry().from_key_hashed_nocheck(hash, &k), kv);
2088	/// }
2089	/// ```
2090	#[cfg_attr(feature = "inline-more", inline)]
2091	pub fn raw_entry(&self) -> RawEntryBuilder<'_, K, V, S, A> {
2092	RawEntryBuilder { map: self }
2093	}
2094
2095	/// Returns a reference to the [`RawTable`] used underneath [`HashMap`].
2096	/// This function is only available if the `raw` feature of the crate is enabled.
2097	///
2098	/// See [`raw_table_mut`] for more.
2099	///
2100	/// [`raw_table_mut`]: Self::raw_table_mut
2101	#[cfg(feature = "raw")]
2102	#[cfg_attr(feature = "inline-more", inline)]
2103	pub fn raw_table(&self) -> &RawTable<(K, V), A> {
2104	&self.table
2105	}
2106
2107	/// Returns a mutable reference to the [`RawTable`] used underneath [`HashMap`].
2108	/// This function is only available if the `raw` feature of the crate is enabled.
2109	///
2110	/// # Note
2111	///
2112	/// Calling this function is safe, but using the raw hash table API may require
2113	/// unsafe functions or blocks.
2114	///
2115	/// `RawTable` API gives the lowest level of control under the map that can be useful
2116	/// for extending the HashMap's API, but may lead to [undefined behavior].
2117	///
2118	/// [`HashMap`]: struct.HashMap.html
2119	/// [`RawTable`]: crate::raw::RawTable
2120	/// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
2121	///
2122	/// # Examples
2123	///
2124	/// ```
2125	/// use core::hash::{BuildHasher, Hash};
2126	/// use hashbrown::HashMap;
2127	///
2128	/// let mut map = HashMap::new();
2129	/// map.extend([("a", 10), ("b", 20), ("c", 30)]);
2130	/// assert_eq!(map.len(), 3);
2131	///
2132	/// // Let's imagine that we have a value and a hash of the key, but not the key itself.
2133	/// // However, if you want to remove the value from the map by hash and value, and you
2134	/// // know exactly that the value is unique, then you can create a function like this:
2135	/// fn remove_by_hash<K, V, S, F>(
2136	/// map: &mut HashMap<K, V, S>,
2137	/// hash: u64,
2138	/// is_match: F,
2139	/// ) -> Option<(K, V)>
2140	/// where
2141	/// F: Fn(&(K, V)) -> bool,
2142	/// {
2143	/// let raw_table = map.raw_table_mut();
2144	/// match raw_table.find(hash, is_match) {
2145	/// Some(bucket) => Some(unsafe { raw_table.remove(bucket).0 }),
2146	/// None => None,
2147	/// }
2148	/// }
2149	///
2150	/// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
2151	/// use core::hash::Hasher;
2152	/// let mut state = hash_builder.build_hasher();
2153	/// key.hash(&mut state);
2154	/// state.finish()
2155	/// }
2156	///
2157	/// let hash = compute_hash(map.hasher(), "a");
2158	/// assert_eq!(remove_by_hash(&mut map, hash, \|(_, v)\| v == 10), Some(("a", 10)));*
2159	/// assert_eq!(map.get(&"a"), None);
2160	/// assert_eq!(map.len(), 2);
2161	/// ```
2162	#[cfg(feature = "raw")]
2163	#[cfg_attr(feature = "inline-more", inline)]
2164	pub fn raw_table_mut(&mut self) -> &mut RawTable<(K, V), A> {
2165	&mut self.table
2166	}
2167	}
2168
2169	impl<K, V, S, A> PartialEq for HashMap<K, V, S, A>
2170	where
2171	K: Eq + Hash,
2172	V: PartialEq,
2173	S: BuildHasher,
2174	A: Allocator,
2175	{
2176	fn eq(&self, other: &Self) -> bool {
2177	if self.len() != other.len() {
2178	return `false`;
2179	}
2180
2181	self.iter()
2182	.all(\|(key: &K, value: &V)\| other.get(key).map_or(default:`false`, \|v: &V\| value == v))
2183	}
2184	}
2185
2186	impl<K, V, S, A> Eq for HashMap<K, V, S, A>
2187	where
2188	K: Eq + Hash,
2189	V: Eq,
2190	S: BuildHasher,
2191	A: Allocator,
2192	{
2193	}
2194
2195	impl<K, V, S, A> Debug for HashMap<K, V, S, A>
2196	where
2197	K: Debug,
2198	V: Debug,
2199	A: Allocator,
2200	{
2201	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2202	f.debug_map().entries(self.iter()).finish()
2203	}
2204	}
2205
2206	impl<K, V, S, A> Default for HashMap<K, V, S, A>
2207	where
2208	S: Default,
2209	A: Default + Allocator,
2210	{
2211	/// Creates an empty `HashMap<K, V, S, A>`, with the `Default` value for the hasher and allocator.
2212	///
2213	/// # Examples
2214	///
2215	/// ```
2216	/// use hashbrown::HashMap;
2217	/// use std::collections::hash_map::RandomState;
2218	///
2219	/// // You can specify all types of HashMap, including hasher and allocator.
2220	/// // Created map is empty and don't allocate memory
2221	/// let map: HashMap<u32, String> = Default::default();
2222	/// assert_eq!(map.capacity(), `0`);
2223	/// let map: HashMap<u32, String, RandomState> = HashMap::default();
2224	/// assert_eq!(map.capacity(), `0`);
2225	/// ```
2226	#[cfg_attr(feature = "inline-more", inline)]
2227	fn default() -> Self {
2228	Self::with_hasher_in(hash_builder:Default::default(), alloc:Default::default())
2229	}
2230	}
2231
2232	impl<K, Q: ?Sized, V, S, A> Index<&Q> for HashMap<K, V, S, A>
2233	where
2234	K: Eq + Hash,
2235	Q: Hash + Equivalent<K>,
2236	S: BuildHasher,
2237	A: Allocator,
2238	{
2239	type Output = V;
2240
2241	/// Returns a reference to the value corresponding to the supplied key.
2242	///
2243	/// # Panics
2244	///
2245	/// Panics if the key is not present in the `HashMap`.
2246	///
2247	/// # Examples
2248	///
2249	/// ```
2250	/// use hashbrown::HashMap;
2251	///
2252	/// let map: HashMap<_, _> = [("a", "One"), ("b", "Two")].into();
2253	///
2254	/// assert_eq!(map[&"a"], "One");
2255	/// assert_eq!(map[&"b"], "Two");
2256	/// ```
2257	#[cfg_attr(feature = "inline-more", inline)]
2258	fn index(&self, key: &Q) -> &V {
2259	self.get(key).expect(msg:"no entry found for key")
2260	}
2261	}
2262
2263	// The default hasher is used to match the std implementation signature
2264	#[cfg(feature = "ahash")]
2265	impl<K, V, A, const N: usize> From<[(K, V); N]> for HashMap<K, V, DefaultHashBuilder, A>
2266	where
2267	K: Eq + Hash,
2268	A: Default + Allocator,
2269	{
2270	/// # Examples
2271	///
2272	/// ```
2273	/// use hashbrown::HashMap;
2274	///
2275	/// let map1 = HashMap::from([(1, 2), (3, 4)]);
2276	/// let map2: HashMap<_, _> = [(1, 2), (3, 4)].into();
2277	/// assert_eq!(map1, map2);
2278	/// ```
2279	fn from(arr: [(K, V); N]) -> Self {
2280	arr.into_iter().collect()
2281	}
2282	}
2283
2284	/// An iterator over the entries of a `HashMap` in arbitrary order.
2285	/// The iterator element type is `(&'a K, &'a V)`.
2286	///
2287	/// This `struct` is created by the [`iter`] method on [`HashMap`]. See its
2288	/// documentation for more.
2289	///
2290	/// [`iter`]: struct.HashMap.html#method.iter
2291	/// [`HashMap`]: struct.HashMap.html
2292	///
2293	/// # Examples
2294	///
2295	/// ```
2296	/// use hashbrown::HashMap;
2297	///
2298	/// let map: HashMap<_, _> = [(`1`, "a"), (`2`, "b"), (`3`, "c")].into();
2299	///
2300	/// let mut iter = map.iter();
2301	/// let mut vec = vec![iter.next(), iter.next(), iter.next()];
2302	///
2303	/// // The `Iter` iterator produces items in arbitrary order, so the
2304	/// // items must be sorted to test them against a sorted array.
2305	/// vec.sort_unstable();
2306	/// assert_eq!(vec, [Some((&`1`, &"a")), Some((&`2`, &"b")), Some((&`3`, &"c"))]);
2307	///
2308	/// // It is fused iterator
2309	/// assert_eq!(iter.next(), None);
2310	/// assert_eq!(iter.next(), None);
2311	/// ```
2312	pub struct Iter<'a, K, V> {
2313	inner: RawIter<(K, V)>,
2314	marker: PhantomData<(&'a K, &'a V)>,
2315	}
2316
2317	// FIXME(#26925) Remove in favor of `#[derive(Clone)]`
2318	impl<K, V> Clone for Iter<'_, K, V> {
2319	#[cfg_attr(feature = "inline-more", inline)]
2320	fn clone(&self) -> Self {
2321	Iter {
2322	inner: self.inner.clone(),
2323	marker: PhantomData,
2324	}
2325	}
2326	}
2327
2328	impl<K: Debug, V: Debug> fmt::Debug for Iter<'_, K, V> {
2329	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2330	f.debug_list().entries(self.clone()).finish()
2331	}
2332	}
2333
2334	/// A mutable iterator over the entries of a `HashMap` in arbitrary order.
2335	/// The iterator element type is `(&'a K, &'a mut V)`.
2336	///
2337	/// This `struct` is created by the [`iter_mut`] method on [`HashMap`]. See its
2338	/// documentation for more.
2339	///
2340	/// [`iter_mut`]: struct.HashMap.html#method.iter_mut
2341	/// [`HashMap`]: struct.HashMap.html
2342	///
2343	/// # Examples
2344	///
2345	/// ```
2346	/// use hashbrown::HashMap;
2347	///
2348	/// let mut map: HashMap<_, _> = [(`1`, "One".to_owned()), (`2`, "Two".into())].into();
2349	///
2350	/// let mut iter = map.iter_mut();
2351	/// iter.next().map(\|(_, v)\| v.push_str(" Mississippi"));
2352	/// iter.next().map(\|(_, v)\| v.push_str(" Mississippi"));
2353	///
2354	/// // It is fused iterator
2355	/// assert_eq!(iter.next(), None);
2356	/// assert_eq!(iter.next(), None);
2357	///
2358	/// assert_eq!(map.get(&`1`).unwrap(), &"One Mississippi".to_owned());
2359	/// assert_eq!(map.get(&`2`).unwrap(), &"Two Mississippi".to_owned());
2360	/// ```
2361	pub struct IterMut<'a, K, V> {
2362	inner: RawIter<(K, V)>,
2363	// To ensure invariance with respect to V
2364	marker: PhantomData<(&'a K, &'a mut V)>,
2365	}
2366
2367	// We override the default Send impl which has K: Sync instead of K: Send. Both
2368	// are correct, but this one is more general since it allows keys which
2369	// implement Send but not Sync.
2370	unsafe impl<K: Send, V: Send> Send for IterMut<'_, K, V> {}
2371
2372	impl<K, V> IterMut<'_, K, V> {
2373	/// Returns a iterator of references over the remaining items.
2374	#[cfg_attr(feature = "inline-more", inline)]
2375	pub(super) fn iter(&self) -> Iter<'_, K, V> {
2376	Iter {
2377	inner: self.inner.clone(),
2378	marker: PhantomData,
2379	}
2380	}
2381	}
2382
2383	/// An owning iterator over the entries of a `HashMap` in arbitrary order.
2384	/// The iterator element type is `(K, V)`.
2385	///
2386	/// This `struct` is created by the [`into_iter`] method on [`HashMap`]
2387	/// (provided by the [`IntoIterator`] trait). See its documentation for more.
2388	/// The map cannot be used after calling that method.
2389	///
2390	/// [`into_iter`]: struct.HashMap.html#method.into_iter
2391	/// [`HashMap`]: struct.HashMap.html
2392	/// [`IntoIterator`]: https://doc.rust-lang.org/core/iter/trait.IntoIterator.html
2393	///
2394	/// # Examples
2395	///
2396	/// ```
2397	/// use hashbrown::HashMap;
2398	///
2399	/// let map: HashMap<_, _> = [(`1`, "a"), (`2`, "b"), (`3`, "c")].into();
2400	///
2401	/// let mut iter = map.into_iter();
2402	/// let mut vec = vec![iter.next(), iter.next(), iter.next()];
2403	///
2404	/// // The `IntoIter` iterator produces items in arbitrary order, so the
2405	/// // items must be sorted to test them against a sorted array.
2406	/// vec.sort_unstable();
2407	/// assert_eq!(vec, [Some((`1`, "a")), Some((`2`, "b")), Some((`3`, "c"))]);
2408	///
2409	/// // It is fused iterator
2410	/// assert_eq!(iter.next(), None);
2411	/// assert_eq!(iter.next(), None);
2412	/// ```
2413	pub struct IntoIter<K, V, A: Allocator = Global> {
2414	inner: RawIntoIter<(K, V), A>,
2415	}
2416
2417	impl<K, V, A: Allocator> IntoIter<K, V, A> {
2418	/// Returns a iterator of references over the remaining items.
2419	#[cfg_attr(feature = "inline-more", inline)]
2420	pub(super) fn iter(&self) -> Iter<'_, K, V> {
2421	Iter {
2422	inner: self.inner.iter(),
2423	marker: PhantomData,
2424	}
2425	}
2426	}
2427
2428	/// An owning iterator over the keys of a `HashMap` in arbitrary order.
2429	/// The iterator element type is `K`.
2430	///
2431	/// This `struct` is created by the [`into_keys`] method on [`HashMap`].
2432	/// See its documentation for more.
2433	/// The map cannot be used after calling that method.
2434	///
2435	/// [`into_keys`]: struct.HashMap.html#method.into_keys
2436	/// [`HashMap`]: struct.HashMap.html
2437	///
2438	/// # Examples
2439	///
2440	/// ```
2441	/// use hashbrown::HashMap;
2442	///
2443	/// let map: HashMap<_, _> = [(`1`, "a"), (`2`, "b"), (`3`, "c")].into();
2444	///
2445	/// let mut keys = map.into_keys();
2446	/// let mut vec = vec![keys.next(), keys.next(), keys.next()];
2447	///
2448	/// // The `IntoKeys` iterator produces keys in arbitrary order, so the
2449	/// // keys must be sorted to test them against a sorted array.
2450	/// vec.sort_unstable();
2451	/// assert_eq!(vec, [Some(`1`), Some(`2`), Some(`3`)]);
2452	///
2453	/// // It is fused iterator
2454	/// assert_eq!(keys.next(), None);
2455	/// assert_eq!(keys.next(), None);
2456	/// ```
2457	pub struct IntoKeys<K, V, A: Allocator = Global> {
2458	inner: IntoIter<K, V, A>,
2459	}
2460
2461	impl<K, V, A: Allocator> Iterator for IntoKeys<K, V, A> {
2462	type Item = K;
2463
2464	#[inline]
2465	fn next(&mut self) -> Option<K> {
2466	self.inner.next().map(\|(k: K, _)\| k)
2467	}
2468	#[inline]
2469	fn size_hint(&self) -> (usize, Option<usize>) {
2470	self.inner.size_hint()
2471	}
2472	#[inline]
2473	fn fold<B, F>(self, init: B, mut f: F) -> B
2474	where
2475	Self: Sized,
2476	F: FnMut(B, Self::Item) -> B,
2477	{
2478	self.inner.fold(init, \|acc: B, (k: K, _)\| f(acc, k))
2479	}
2480	}
2481
2482	impl<K, V, A: Allocator> ExactSizeIterator for IntoKeys<K, V, A> {
2483	#[inline]
2484	fn len(&self) -> usize {
2485	self.inner.len()
2486	}
2487	}
2488
2489	impl<K, V, A: Allocator> FusedIterator for IntoKeys<K, V, A> {}
2490
2491	impl<K: Debug, V: Debug, A: Allocator> fmt::Debug for IntoKeys<K, V, A> {
2492	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2493	f&mut DebugList<'_, '_>.debug_list()
2494	.entries(self.inner.iter().map(\|(k: &K, _)\| k))
2495	.finish()
2496	}
2497	}
2498
2499	/// An owning iterator over the values of a `HashMap` in arbitrary order.
2500	/// The iterator element type is `V`.
2501	///
2502	/// This `struct` is created by the [`into_values`] method on [`HashMap`].
2503	/// See its documentation for more. The map cannot be used after calling that method.
2504	///
2505	/// [`into_values`]: struct.HashMap.html#method.into_values
2506	/// [`HashMap`]: struct.HashMap.html
2507	///
2508	/// # Examples
2509	///
2510	/// ```
2511	/// use hashbrown::HashMap;
2512	///
2513	/// let map: HashMap<_, _> = [(`1`, "a"), (`2`, "b"), (`3`, "c")].into();
2514	///
2515	/// let mut values = map.into_values();
2516	/// let mut vec = vec![values.next(), values.next(), values.next()];
2517	///
2518	/// // The `IntoValues` iterator produces values in arbitrary order, so
2519	/// // the values must be sorted to test them against a sorted array.
2520	/// vec.sort_unstable();
2521	/// assert_eq!(vec, [Some("a"), Some("b"), Some("c")]);
2522	///
2523	/// // It is fused iterator
2524	/// assert_eq!(values.next(), None);
2525	/// assert_eq!(values.next(), None);
2526	/// ```
2527	pub struct IntoValues<K, V, A: Allocator = Global> {
2528	inner: IntoIter<K, V, A>,
2529	}
2530
2531	impl<K, V, A: Allocator> Iterator for IntoValues<K, V, A> {
2532	type Item = V;
2533
2534	#[inline]
2535	fn next(&mut self) -> Option<V> {
2536	self.inner.next().map(\|(_, v: V)\| v)
2537	}
2538	#[inline]
2539	fn size_hint(&self) -> (usize, Option<usize>) {
2540	self.inner.size_hint()
2541	}
2542	#[inline]
2543	fn fold<B, F>(self, init: B, mut f: F) -> B
2544	where
2545	Self: Sized,
2546	F: FnMut(B, Self::Item) -> B,
2547	{
2548	self.inner.fold(init, \|acc: B, (_, v: V)\| f(acc, v))
2549	}
2550	}
2551
2552	impl<K, V, A: Allocator> ExactSizeIterator for IntoValues<K, V, A> {
2553	#[inline]
2554	fn len(&self) -> usize {
2555	self.inner.len()
2556	}
2557	}
2558
2559	impl<K, V, A: Allocator> FusedIterator for IntoValues<K, V, A> {}
2560
2561	impl<K, V: Debug, A: Allocator> fmt::Debug for IntoValues<K, V, A> {
2562	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2563	f&mut DebugList<'_, '_>.debug_list()
2564	.entries(self.inner.iter().map(\|(_, v: &V)\| v))
2565	.finish()
2566	}
2567	}
2568
2569	/// An iterator over the keys of a `HashMap` in arbitrary order.
2570	/// The iterator element type is `&'a K`.
2571	///
2572	/// This `struct` is created by the [`keys`] method on [`HashMap`]. See its
2573	/// documentation for more.
2574	///
2575	/// [`keys`]: struct.HashMap.html#method.keys
2576	/// [`HashMap`]: struct.HashMap.html
2577	///
2578	/// # Examples
2579	///
2580	/// ```
2581	/// use hashbrown::HashMap;
2582	///
2583	/// let map: HashMap<_, _> = [(`1`, "a"), (`2`, "b"), (`3`, "c")].into();
2584	///
2585	/// let mut keys = map.keys();
2586	/// let mut vec = vec![keys.next(), keys.next(), keys.next()];
2587	///
2588	/// // The `Keys` iterator produces keys in arbitrary order, so the
2589	/// // keys must be sorted to test them against a sorted array.
2590	/// vec.sort_unstable();
2591	/// assert_eq!(vec, [Some(&`1`), Some(&`2`), Some(&`3`)]);
2592	///
2593	/// // It is fused iterator
2594	/// assert_eq!(keys.next(), None);
2595	/// assert_eq!(keys.next(), None);
2596	/// ```
2597	pub struct Keys<'a, K, V> {
2598	inner: Iter<'a, K, V>,
2599	}
2600
2601	// FIXME(#26925) Remove in favor of `#[derive(Clone)]`
2602	impl<K, V> Clone for Keys<'_, K, V> {
2603	#[cfg_attr(feature = "inline-more", inline)]
2604	fn clone(&self) -> Self {
2605	Keys {
2606	inner: self.inner.clone(),
2607	}
2608	}
2609	}
2610
2611	impl<K: Debug, V> fmt::Debug for Keys<'_, K, V> {
2612	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2613	f.debug_list().entries(self.clone()).finish()
2614	}
2615	}
2616
2617	/// An iterator over the values of a `HashMap` in arbitrary order.
2618	/// The iterator element type is `&'a V`.
2619	///
2620	/// This `struct` is created by the [`values`] method on [`HashMap`]. See its
2621	/// documentation for more.
2622	///
2623	/// [`values`]: struct.HashMap.html#method.values
2624	/// [`HashMap`]: struct.HashMap.html
2625	///
2626	/// # Examples
2627	///
2628	/// ```
2629	/// use hashbrown::HashMap;
2630	///
2631	/// let map: HashMap<_, _> = [(`1`, "a"), (`2`, "b"), (`3`, "c")].into();
2632	///
2633	/// let mut values = map.values();
2634	/// let mut vec = vec![values.next(), values.next(), values.next()];
2635	///
2636	/// // The `Values` iterator produces values in arbitrary order, so the
2637	/// // values must be sorted to test them against a sorted array.
2638	/// vec.sort_unstable();
2639	/// assert_eq!(vec, [Some(&"a"), Some(&"b"), Some(&"c")]);
2640	///
2641	/// // It is fused iterator
2642	/// assert_eq!(values.next(), None);
2643	/// assert_eq!(values.next(), None);
2644	/// ```
2645	pub struct Values<'a, K, V> {
2646	inner: Iter<'a, K, V>,
2647	}
2648
2649	// FIXME(#26925) Remove in favor of `#[derive(Clone)]`
2650	impl<K, V> Clone for Values<'_, K, V> {
2651	#[cfg_attr(feature = "inline-more", inline)]
2652	fn clone(&self) -> Self {
2653	Values {
2654	inner: self.inner.clone(),
2655	}
2656	}
2657	}
2658
2659	impl<K, V: Debug> fmt::Debug for Values<'_, K, V> {
2660	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2661	f.debug_list().entries(self.clone()).finish()
2662	}
2663	}
2664
2665	/// A draining iterator over the entries of a `HashMap` in arbitrary
2666	/// order. The iterator element type is `(K, V)`.
2667	///
2668	/// This `struct` is created by the [`drain`] method on [`HashMap`]. See its
2669	/// documentation for more.
2670	///
2671	/// [`drain`]: struct.HashMap.html#method.drain
2672	/// [`HashMap`]: struct.HashMap.html
2673	///
2674	/// # Examples
2675	///
2676	/// ```
2677	/// use hashbrown::HashMap;
2678	///
2679	/// let mut map: HashMap<_, _> = [(`1`, "a"), (`2`, "b"), (`3`, "c")].into();
2680	///
2681	/// let mut drain_iter = map.drain();
2682	/// let mut vec = vec![drain_iter.next(), drain_iter.next(), drain_iter.next()];
2683	///
2684	/// // The `Drain` iterator produces items in arbitrary order, so the
2685	/// // items must be sorted to test them against a sorted array.
2686	/// vec.sort_unstable();
2687	/// assert_eq!(vec, [Some((`1`, "a")), Some((`2`, "b")), Some((`3`, "c"))]);
2688	///
2689	/// // It is fused iterator
2690	/// assert_eq!(drain_iter.next(), None);
2691	/// assert_eq!(drain_iter.next(), None);
2692	/// ```
2693	pub struct Drain<'a, K, V, A: Allocator = Global> {
2694	inner: RawDrain<'a, (K, V), A>,
2695	}
2696
2697	impl<K, V, A: Allocator> Drain<'_, K, V, A> {
2698	/// Returns a iterator of references over the remaining items.
2699	#[cfg_attr(feature = "inline-more", inline)]
2700	pub(super) fn iter(&self) -> Iter<'_, K, V> {
2701	Iter {
2702	inner: self.inner.iter(),
2703	marker: PhantomData,
2704	}
2705	}
2706	}
2707
2708	/// A draining iterator over entries of a `HashMap` which don't satisfy the predicate
2709	/// `f(&k, &mut v)` in arbitrary order. The iterator element type is `(K, V)`.
2710	///
2711	/// This `struct` is created by the [`extract_if`] method on [`HashMap`]. See its
2712	/// documentation for more.
2713	///
2714	/// [`extract_if`]: struct.HashMap.html#method.extract_if
2715	/// [`HashMap`]: struct.HashMap.html
2716	///
2717	/// # Examples
2718	///
2719	/// ```
2720	/// use hashbrown::HashMap;
2721	///
2722	/// let mut map: HashMap<i32, &str> = [(`1`, "a"), (`2`, "b"), (`3`, "c")].into();
2723	///
2724	/// let mut extract_if = map.extract_if(\|k, _v\| k % `2` != `0`);
2725	/// let mut vec = vec![extract_if.next(), extract_if.next()];
2726	///
2727	/// // The `ExtractIf` iterator produces items in arbitrary order, so the
2728	/// // items must be sorted to test them against a sorted array.
2729	/// vec.sort_unstable();
2730	/// assert_eq!(vec, [Some((`1`, "a")),Some((`3`, "c"))]);
2731	///
2732	/// // It is fused iterator
2733	/// assert_eq!(extract_if.next(), None);
2734	/// assert_eq!(extract_if.next(), None);
2735	/// drop(extract_if);
2736	///
2737	/// assert_eq!(map.len(), `1`);
2738	/// ```
2739	#[must_use = "Iterators are lazy unless consumed"]
2740	pub struct ExtractIf<'a, K, V, F, A: Allocator = Global>
2741	where
2742	F: FnMut(&K, &mut V) -> bool,
2743	{
2744	f: F,
2745	inner: RawExtractIf<'a, (K, V), A>,
2746	}
2747
2748	impl<K, V, F, A> Iterator for ExtractIf<'_, K, V, F, A>
2749	where
2750	F: FnMut(&K, &mut V) -> bool,
2751	A: Allocator,
2752	{
2753	type Item = (K, V);
2754
2755	#[cfg_attr(feature = "inline-more", inline)]
2756	fn next(&mut self) -> Option<Self::Item> {
2757	self.inner.next(\|&mut (ref k: &K, ref mut v: &mut V)\| (self.f)(k, v))
2758	}
2759
2760	#[inline]
2761	fn size_hint(&self) -> (usize, Option<usize>) {
2762	(`0`, self.inner.iter.size_hint().1)
2763	}
2764	}
2765
2766	impl<K, V, F> FusedIterator for ExtractIf<'_, K, V, F> where F: FnMut(&K, &mut V) -> bool {}
2767
2768	/// A mutable iterator over the values of a `HashMap` in arbitrary order.
2769	/// The iterator element type is `&'a mut V`.
2770	///
2771	/// This `struct` is created by the [`values_mut`] method on [`HashMap`]. See its
2772	/// documentation for more.
2773	///
2774	/// [`values_mut`]: struct.HashMap.html#method.values_mut
2775	/// [`HashMap`]: struct.HashMap.html
2776	///
2777	/// # Examples
2778	///
2779	/// ```
2780	/// use hashbrown::HashMap;
2781	///
2782	/// let mut map: HashMap<_, _> = [(`1`, "One".to_owned()), (`2`, "Two".into())].into();
2783	///
2784	/// let mut values = map.values_mut();
2785	/// values.next().map(\|v\| v.push_str(" Mississippi"));
2786	/// values.next().map(\|v\| v.push_str(" Mississippi"));
2787	///
2788	/// // It is fused iterator
2789	/// assert_eq!(values.next(), None);
2790	/// assert_eq!(values.next(), None);
2791	///
2792	/// assert_eq!(map.get(&`1`).unwrap(), &"One Mississippi".to_owned());
2793	/// assert_eq!(map.get(&`2`).unwrap(), &"Two Mississippi".to_owned());
2794	/// ```
2795	pub struct ValuesMut<'a, K, V> {
2796	inner: IterMut<'a, K, V>,
2797	}
2798
2799	/// A builder for computing where in a [`HashMap`] a key-value pair would be stored.
2800	///
2801	/// See the [`HashMap::raw_entry_mut`] docs for usage examples.
2802	///
2803	/// [`HashMap::raw_entry_mut`]: struct.HashMap.html#method.raw_entry_mut
2804	///
2805	/// # Examples
2806	///
2807	/// ```
2808	/// use hashbrown::hash_map::{RawEntryBuilderMut, RawEntryMut::Vacant, RawEntryMut::Occupied};
2809	/// use hashbrown::HashMap;
2810	/// use core::hash::{BuildHasher, Hash};
2811	///
2812	/// let mut map = HashMap::new();
2813	/// map.extend([(`1`, `11`), (`2`, `12`), (`3`, `13`), (`4`, `14`), (`5`, `15`), (`6`, `16`)]);
2814	/// assert_eq!(map.len(), `6`);
2815	///
2816	/// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
2817	/// use core::hash::Hasher;
2818	/// let mut state = hash_builder.build_hasher();
2819	/// key.hash(&mut state);
2820	/// state.finish()
2821	/// }
2822	///
2823	/// let builder: RawEntryBuilderMut<_, _, _> = map.raw_entry_mut();
2824	///
2825	/// // Existing key
2826	/// match builder.from_key(&`6`) {
2827	/// Vacant(_) => unreachable!(),
2828	/// Occupied(view) => assert_eq!(view.get(), &`16`),
2829	/// }
2830	///
2831	/// for key in `0`..`12` {
2832	/// let hash = compute_hash(map.hasher(), &key);
2833	/// let value = map.get(&key).cloned();
2834	/// let key_value = value.as_ref().map(\|v\| (&key, v));
2835	///
2836	/// println!("Key: {} and value: {:?}", key, value);
2837	///
2838	/// match map.raw_entry_mut().from_key(&key) {
2839	/// Occupied(mut o) => assert_eq!(Some(o.get_key_value()), key_value),
2840	/// Vacant(_) => assert_eq!(value, None),
2841	/// }
2842	/// match map.raw_entry_mut().from_key_hashed_nocheck(hash, &key) {
2843	/// Occupied(mut o) => assert_eq!(Some(o.get_key_value()), key_value),
2844	/// Vacant(_) => assert_eq!(value, None),
2845	/// }
2846	/// match map.raw_entry_mut().from_hash(hash, \|q\| *q == key) {
2847	/// Occupied(mut o) => assert_eq!(Some(o.get_key_value()), key_value),
2848	/// Vacant(_) => assert_eq!(value, None),
2849	/// }
2850	/// }
2851	///
2852	/// assert_eq!(map.len(), `6`);
2853	/// ```
2854	pub struct RawEntryBuilderMut<'a, K, V, S, A: Allocator = Global> {
2855	map: &'a mut HashMap<K, V, S, A>,
2856	}
2857
2858	/// A view into a single entry in a map, which may either be vacant or occupied.
2859	///
2860	/// This is a lower-level version of [`Entry`].
2861	///
2862	/// This `enum` is constructed through the [`raw_entry_mut`] method on [`HashMap`],
2863	/// then calling one of the methods of that [`RawEntryBuilderMut`].
2864	///
2865	/// [`HashMap`]: struct.HashMap.html
2866	/// [`Entry`]: enum.Entry.html
2867	/// [`raw_entry_mut`]: struct.HashMap.html#method.raw_entry_mut
2868	/// [`RawEntryBuilderMut`]: struct.RawEntryBuilderMut.html
2869	///
2870	/// # Examples
2871	///
2872	/// ```
2873	/// use core::hash::{BuildHasher, Hash};
2874	/// use hashbrown::hash_map::{HashMap, RawEntryMut, RawOccupiedEntryMut};
2875	///
2876	/// let mut map = HashMap::new();
2877	/// map.extend([('a', `1`), ('b', `2`), ('c', `3`)]);
2878	/// assert_eq!(map.len(), `3`);
2879	///
2880	/// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
2881	/// use core::hash::Hasher;
2882	/// let mut state = hash_builder.build_hasher();
2883	/// key.hash(&mut state);
2884	/// state.finish()
2885	/// }
2886	///
2887	/// // Existing key (insert)
2888	/// let raw: RawEntryMut<_, _, _> = map.raw_entry_mut().from_key(&'a');
2889	/// let _raw_o: RawOccupiedEntryMut<_, _, _> = raw.insert('a', `10`);
2890	/// assert_eq!(map.len(), `3`);
2891	///
2892	/// // Nonexistent key (insert)
2893	/// map.raw_entry_mut().from_key(&'d').insert('d', `40`);
2894	/// assert_eq!(map.len(), `4`);
2895	///
2896	/// // Existing key (or_insert)
2897	/// let hash = compute_hash(map.hasher(), &'b');
2898	/// let kv = map
2899	/// .raw_entry_mut()
2900	/// .from_key_hashed_nocheck(hash, &'b')
2901	/// .or_insert('b', `20`);
2902	/// assert_eq!(kv, (&mut 'b', &mut `2`));
2903	/// *kv.1 = `20`;
2904	/// assert_eq!(map.len(), `4`);
2905	///
2906	/// // Nonexistent key (or_insert)
2907	/// let hash = compute_hash(map.hasher(), &'e');
2908	/// let kv = map
2909	/// .raw_entry_mut()
2910	/// .from_key_hashed_nocheck(hash, &'e')
2911	/// .or_insert('e', `50`);
2912	/// assert_eq!(kv, (&mut 'e', &mut `50`));
2913	/// assert_eq!(map.len(), `5`);
2914	///
2915	/// // Existing key (or_insert_with)
2916	/// let hash = compute_hash(map.hasher(), &'c');
2917	/// let kv = map
2918	/// .raw_entry_mut()
2919	/// .from_hash(hash, \|q\| q == &'c')
2920	/// .or_insert_with(\|\| ('c', `30`));
2921	/// assert_eq!(kv, (&mut 'c', &mut `3`));
2922	/// *kv.1 = `30`;
2923	/// assert_eq!(map.len(), `5`);
2924	///
2925	/// // Nonexistent key (or_insert_with)
2926	/// let hash = compute_hash(map.hasher(), &'f');
2927	/// let kv = map
2928	/// .raw_entry_mut()
2929	/// .from_hash(hash, \|q\| q == &'f')
2930	/// .or_insert_with(\|\| ('f', `60`));
2931	/// assert_eq!(kv, (&mut 'f', &mut `60`));
2932	/// assert_eq!(map.len(), `6`);
2933	///
2934	/// println!("Our HashMap: {:?}", map);
2935	///
2936	/// let mut vec: Vec<_> = map.iter().map(\|(&k, &v)\| (k, v)).collect();
2937	/// // The `Iter` iterator produces items in arbitrary order, so the
2938	/// // items must be sorted to test them against a sorted array.
2939	/// vec.sort_unstable();
2940	/// assert_eq!(vec, [('a', `10`), ('b', `20`), ('c', `30`), ('d', `40`), ('e', `50`), ('f', `60`)]);
2941	/// ```
2942	pub enum RawEntryMut<'a, K, V, S, A: Allocator = Global> {
2943	/// An occupied entry.
2944	///
2945	/// # Examples
2946	///
2947	/// ```
2948	/// use hashbrown::{hash_map::RawEntryMut, HashMap};
2949	/// let mut map: HashMap<_, _> = [("a", `100`), ("b", `200`)].into();
2950	///
2951	/// match map.raw_entry_mut().from_key(&"a") {
2952	/// RawEntryMut::Vacant(_) => unreachable!(),
2953	/// RawEntryMut::Occupied(_) => { }
2954	/// }
2955	/// ```
2956	Occupied(RawOccupiedEntryMut<'a, K, V, S, A>),
2957	/// A vacant entry.
2958	///
2959	/// # Examples
2960	///
2961	/// ```
2962	/// use hashbrown::{hash_map::RawEntryMut, HashMap};
2963	/// let mut map: HashMap<&str, i32> = HashMap::new();
2964	///
2965	/// match map.raw_entry_mut().from_key("a") {
2966	/// RawEntryMut::Occupied(_) => unreachable!(),
2967	/// RawEntryMut::Vacant(_) => { }
2968	/// }
2969	/// ```
2970	Vacant(RawVacantEntryMut<'a, K, V, S, A>),
2971	}
2972
2973	/// A view into an occupied entry in a `HashMap`.
2974	/// It is part of the [`RawEntryMut`] enum.
2975	///
2976	/// [`RawEntryMut`]: enum.RawEntryMut.html
2977	///
2978	/// # Examples
2979	///
2980	/// ```
2981	/// use core::hash::{BuildHasher, Hash};
2982	/// use hashbrown::hash_map::{HashMap, RawEntryMut, RawOccupiedEntryMut};
2983	///
2984	/// let mut map = HashMap::new();
2985	/// map.extend([("a", `10`), ("b", `20`), ("c", `30`)]);
2986	///
2987	/// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
2988	/// use core::hash::Hasher;
2989	/// let mut state = hash_builder.build_hasher();
2990	/// key.hash(&mut state);
2991	/// state.finish()
2992	/// }
2993	///
2994	/// let _raw_o: RawOccupiedEntryMut<_, _, _> = map.raw_entry_mut().from_key(&"a").insert("a", `100`);
2995	/// assert_eq!(map.len(), `3`);
2996	///
2997	/// // Existing key (insert and update)
2998	/// match map.raw_entry_mut().from_key(&"a") {
2999	/// RawEntryMut::Vacant(_) => unreachable!(),
3000	/// RawEntryMut::Occupied(mut view) => {
3001	/// assert_eq!(view.get(), &`100`);
3002	/// let v = view.get_mut();
3003	/// let new_v = (v) `10`;
3004	/// *v = new_v;
3005	/// assert_eq!(view.insert(`1111`), `1000`);
3006	/// }
3007	/// }
3008	///
3009	/// assert_eq!(map[&"a"], `1111`);
3010	/// assert_eq!(map.len(), `3`);
3011	///
3012	/// // Existing key (take)
3013	/// let hash = compute_hash(map.hasher(), &"c");
3014	/// match map.raw_entry_mut().from_key_hashed_nocheck(hash, &"c") {
3015	/// RawEntryMut::Vacant(_) => unreachable!(),
3016	/// RawEntryMut::Occupied(view) => {
3017	/// assert_eq!(view.remove_entry(), ("c", `30`));
3018	/// }
3019	/// }
3020	/// assert_eq!(map.raw_entry().from_key(&"c"), None);
3021	/// assert_eq!(map.len(), `2`);
3022	///
3023	/// let hash = compute_hash(map.hasher(), &"b");
3024	/// match map.raw_entry_mut().from_hash(hash, \|q\| *q == "b") {
3025	/// RawEntryMut::Vacant(_) => unreachable!(),
3026	/// RawEntryMut::Occupied(view) => {
3027	/// assert_eq!(view.remove_entry(), ("b", `20`));
3028	/// }
3029	/// }
3030	/// assert_eq!(map.get(&"b"), None);
3031	/// assert_eq!(map.len(), `1`);
3032	/// ```
3033	pub struct RawOccupiedEntryMut<'a, K, V, S, A: Allocator = Global> {
3034	elem: Bucket<(K, V)>,
3035	table: &'a mut RawTable<(K, V), A>,
3036	hash_builder: &'a S,
3037	}
3038
3039	unsafe impl<K, V, S, A> Send for RawOccupiedEntryMut<'_, K, V, S, A>
3040	where
3041	K: Send,
3042	V: Send,
3043	S: Send,
3044	A: Send + Allocator,
3045	{
3046	}
3047	unsafe impl<K, V, S, A> Sync for RawOccupiedEntryMut<'_, K, V, S, A>
3048	where
3049	K: Sync,
3050	V: Sync,
3051	S: Sync,
3052	A: Sync + Allocator,
3053	{
3054	}
3055
3056	/// A view into a vacant entry in a `HashMap`.
3057	/// It is part of the [`RawEntryMut`] enum.
3058	///
3059	/// [`RawEntryMut`]: enum.RawEntryMut.html
3060	///
3061	/// # Examples
3062	///
3063	/// ```
3064	/// use core::hash::{BuildHasher, Hash};
3065	/// use hashbrown::hash_map::{HashMap, RawEntryMut, RawVacantEntryMut};
3066	///
3067	/// let mut map = HashMap::<&str, i32>::new();
3068	///
3069	/// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
3070	/// use core::hash::Hasher;
3071	/// let mut state = hash_builder.build_hasher();
3072	/// key.hash(&mut state);
3073	/// state.finish()
3074	/// }
3075	///
3076	/// let raw_v: RawVacantEntryMut<_, _, _> = match map.raw_entry_mut().from_key(&"a") {
3077	/// RawEntryMut::Vacant(view) => view,
3078	/// RawEntryMut::Occupied(_) => unreachable!(),
3079	/// };
3080	/// raw_v.insert("a", `10`);
3081	/// assert!(map[&"a"] == `10` && map.len() == `1`);
3082	///
3083	/// // Nonexistent key (insert and update)
3084	/// let hash = compute_hash(map.hasher(), &"b");
3085	/// match map.raw_entry_mut().from_key_hashed_nocheck(hash, &"b") {
3086	/// RawEntryMut::Occupied(_) => unreachable!(),
3087	/// RawEntryMut::Vacant(view) => {
3088	/// let (k, value) = view.insert("b", `2`);
3089	/// assert_eq!((k, value), ("b", `2`));
3090	/// *value = `20`;
3091	/// }
3092	/// }
3093	/// assert!(map[&"b"] == `20` && map.len() == `2`);
3094	///
3095	/// let hash = compute_hash(map.hasher(), &"c");
3096	/// match map.raw_entry_mut().from_hash(hash, \|q\| *q == "c") {
3097	/// RawEntryMut::Occupied(_) => unreachable!(),
3098	/// RawEntryMut::Vacant(view) => {
3099	/// assert_eq!(view.insert("c", `30`), (&mut "c", &mut `30`));
3100	/// }
3101	/// }
3102	/// assert!(map[&"c"] == `30` && map.len() == `3`);
3103	/// ```
3104	pub struct RawVacantEntryMut<'a, K, V, S, A: Allocator = Global> {
3105	table: &'a mut RawTable<(K, V), A>,
3106	hash_builder: &'a S,
3107	}
3108
3109	/// A builder for computing where in a [`HashMap`] a key-value pair would be stored.
3110	///
3111	/// See the [`HashMap::raw_entry`] docs for usage examples.
3112	///
3113	/// [`HashMap::raw_entry`]: struct.HashMap.html#method.raw_entry
3114	///
3115	/// # Examples
3116	///
3117	/// ```
3118	/// use hashbrown::hash_map::{HashMap, RawEntryBuilder};
3119	/// use core::hash::{BuildHasher, Hash};
3120	///
3121	/// let mut map = HashMap::new();
3122	/// map.extend([(`1`, `10`), (`2`, `20`), (`3`, `30`)]);
3123	///
3124	/// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
3125	/// use core::hash::Hasher;
3126	/// let mut state = hash_builder.build_hasher();
3127	/// key.hash(&mut state);
3128	/// state.finish()
3129	/// }
3130	///
3131	/// for k in `0`..`6` {
3132	/// let hash = compute_hash(map.hasher(), &k);
3133	/// let v = map.get(&k).cloned();
3134	/// let kv = v.as_ref().map(\|v\| (&k, v));
3135	///
3136	/// println!("Key: {} and value: {:?}", k, v);
3137	/// let builder: RawEntryBuilder<_, _, _> = map.raw_entry();
3138	/// assert_eq!(builder.from_key(&k), kv);
3139	/// assert_eq!(map.raw_entry().from_hash(hash, \|q\| *q == k), kv);
3140	/// assert_eq!(map.raw_entry().from_key_hashed_nocheck(hash, &k), kv);
3141	/// }
3142	/// ```
3143	pub struct RawEntryBuilder<'a, K, V, S, A: Allocator = Global> {
3144	map: &'a HashMap<K, V, S, A>,
3145	}
3146
3147	impl<'a, K, V, S, A: Allocator> RawEntryBuilderMut<'a, K, V, S, A> {
3148	/// Creates a `RawEntryMut` from the given key.
3149	///
3150	/// # Examples
3151	///
3152	/// ```
3153	/// use hashbrown::hash_map::{HashMap, RawEntryMut};
3154	///
3155	/// let mut map: HashMap<&str, u32> = HashMap::new();
3156	/// let key = "a";
3157	/// let entry: RawEntryMut<&str, u32, _> = map.raw_entry_mut().from_key(&key);
3158	/// entry.insert(key, `100`);
3159	/// assert_eq!(map[&"a"], `100`);
3160	/// ```
3161	#[cfg_attr(feature = "inline-more", inline)]
3162	#[allow(clippy::wrong_self_convention)]
3163	pub fn from_key<Q: ?Sized>(self, k: &Q) -> RawEntryMut<'a, K, V, S, A>
3164	where
3165	S: BuildHasher,
3166	Q: Hash + Equivalent<K>,
3167	{
3168	let hash = make_hash::<Q, S>(&self.map.hash_builder, k);
3169	self.from_key_hashed_nocheck(hash, k)
3170	}
3171
3172	/// Creates a `RawEntryMut` from the given key and its hash.
3173	///
3174	/// # Examples
3175	///
3176	/// ```
3177	/// use core::hash::{BuildHasher, Hash};
3178	/// use hashbrown::hash_map::{HashMap, RawEntryMut};
3179	///
3180	/// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
3181	/// use core::hash::Hasher;
3182	/// let mut state = hash_builder.build_hasher();
3183	/// key.hash(&mut state);
3184	/// state.finish()
3185	/// }
3186	///
3187	/// let mut map: HashMap<&str, u32> = HashMap::new();
3188	/// let key = "a";
3189	/// let hash = compute_hash(map.hasher(), &key);
3190	/// let entry: RawEntryMut<&str, u32, _> = map.raw_entry_mut().from_key_hashed_nocheck(hash, &key);
3191	/// entry.insert(key, `100`);
3192	/// assert_eq!(map[&"a"], `100`);
3193	/// ```
3194	#[inline]
3195	#[allow(clippy::wrong_self_convention)]
3196	pub fn from_key_hashed_nocheck<Q: ?Sized>(self, hash: u64, k: &Q) -> RawEntryMut<'a, K, V, S, A>
3197	where
3198	Q: Equivalent<K>,
3199	{
3200	self.from_hash(hash, equivalent(k))
3201	}
3202	}
3203
3204	impl<'a, K, V, S, A: Allocator> RawEntryBuilderMut<'a, K, V, S, A> {
3205	/// Creates a `RawEntryMut` from the given hash and matching function.
3206	///
3207	/// # Examples
3208	///
3209	/// ```
3210	/// use core::hash::{BuildHasher, Hash};
3211	/// use hashbrown::hash_map::{HashMap, RawEntryMut};
3212	///
3213	/// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
3214	/// use core::hash::Hasher;
3215	/// let mut state = hash_builder.build_hasher();
3216	/// key.hash(&mut state);
3217	/// state.finish()
3218	/// }
3219	///
3220	/// let mut map: HashMap<&str, u32> = HashMap::new();
3221	/// let key = "a";
3222	/// let hash = compute_hash(map.hasher(), &key);
3223	/// let entry: RawEntryMut<&str, u32, _> = map.raw_entry_mut().from_hash(hash, \|k\| k == &key);
3224	/// entry.insert(key, `100`);
3225	/// assert_eq!(map[&"a"], `100`);
3226	/// ```
3227	#[cfg_attr(feature = "inline-more", inline)]
3228	#[allow(clippy::wrong_self_convention)]
3229	pub fn from_hash<F>(self, hash: u64, is_match: F) -> RawEntryMut<'a, K, V, S, A>
3230	where
3231	for<'b> F: FnMut(&'b K) -> bool,
3232	{
3233	self.search(hash, is_match)
3234	}
3235
3236	#[cfg_attr(feature = "inline-more", inline)]
3237	fn search<F>(self, hash: u64, mut is_match: F) -> RawEntryMut<'a, K, V, S, A>
3238	where
3239	for<'b> F: FnMut(&'b K) -> bool,
3240	{
3241	match self.map.table.find(hash, \|(k, _)\| is_match(k)) {
3242	Some(elem) => RawEntryMut::Occupied(RawOccupiedEntryMut {
3243	elem,
3244	table: &mut self.map.table,
3245	hash_builder: &self.map.hash_builder,
3246	}),
3247	None => RawEntryMut::Vacant(RawVacantEntryMut {
3248	table: &mut self.map.table,
3249	hash_builder: &self.map.hash_builder,
3250	}),
3251	}
3252	}
3253	}
3254
3255	impl<'a, K, V, S, A: Allocator> RawEntryBuilder<'a, K, V, S, A> {
3256	/// Access an immutable entry by key.
3257	///
3258	/// # Examples
3259	///
3260	/// ```
3261	/// use hashbrown::HashMap;
3262	///
3263	/// let map: HashMap<&str, u32> = [("a", `100`), ("b", `200`)].into();
3264	/// let key = "a";
3265	/// assert_eq!(map.raw_entry().from_key(&key), Some((&"a", &`100`)));
3266	/// ```
3267	#[cfg_attr(feature = "inline-more", inline)]
3268	#[allow(clippy::wrong_self_convention)]
3269	pub fn from_key<Q: ?Sized>(self, k: &Q) -> Option<(&'a K, &'a V)>
3270	where
3271	S: BuildHasher,
3272	Q: Hash + Equivalent<K>,
3273	{
3274	let hash = make_hash::<Q, S>(&self.map.hash_builder, k);
3275	self.from_key_hashed_nocheck(hash, k)
3276	}
3277
3278	/// Access an immutable entry by a key and its hash.
3279	///
3280	/// # Examples
3281	///
3282	/// ```
3283	/// use core::hash::{BuildHasher, Hash};
3284	/// use hashbrown::HashMap;
3285	///
3286	/// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
3287	/// use core::hash::Hasher;
3288	/// let mut state = hash_builder.build_hasher();
3289	/// key.hash(&mut state);
3290	/// state.finish()
3291	/// }
3292	///
3293	/// let map: HashMap<&str, u32> = [("a", `100`), ("b", `200`)].into();
3294	/// let key = "a";
3295	/// let hash = compute_hash(map.hasher(), &key);
3296	/// assert_eq!(map.raw_entry().from_key_hashed_nocheck(hash, &key), Some((&"a", &`100`)));
3297	/// ```
3298	#[cfg_attr(feature = "inline-more", inline)]
3299	#[allow(clippy::wrong_self_convention)]
3300	pub fn from_key_hashed_nocheck<Q: ?Sized>(self, hash: u64, k: &Q) -> Option<(&'a K, &'a V)>
3301	where
3302	Q: Equivalent<K>,
3303	{
3304	self.from_hash(hash, equivalent(k))
3305	}
3306
3307	#[cfg_attr(feature = "inline-more", inline)]
3308	fn search<F>(self, hash: u64, mut is_match: F) -> Option<(&'a K, &'a V)>
3309	where
3310	F: FnMut(&K) -> bool,
3311	{
3312	match self.map.table.get(hash, \|(k, _)\| is_match(k)) {
3313	Some((key, value)) => Some((key, value)),
3314	None => None,
3315	}
3316	}
3317
3318	/// Access an immutable entry by hash and matching function.
3319	///
3320	/// # Examples
3321	///
3322	/// ```
3323	/// use core::hash::{BuildHasher, Hash};
3324	/// use hashbrown::HashMap;
3325	///
3326	/// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
3327	/// use core::hash::Hasher;
3328	/// let mut state = hash_builder.build_hasher();
3329	/// key.hash(&mut state);
3330	/// state.finish()
3331	/// }
3332	///
3333	/// let map: HashMap<&str, u32> = [("a", `100`), ("b", `200`)].into();
3334	/// let key = "a";
3335	/// let hash = compute_hash(map.hasher(), &key);
3336	/// assert_eq!(map.raw_entry().from_hash(hash, \|k\| k == &key), Some((&"a", &`100`)));
3337	/// ```
3338	#[cfg_attr(feature = "inline-more", inline)]
3339	#[allow(clippy::wrong_self_convention)]
3340	pub fn from_hash<F>(self, hash: u64, is_match: F) -> Option<(&'a K, &'a V)>
3341	where
3342	F: FnMut(&K) -> bool,
3343	{
3344	self.search(hash, is_match)
3345	}
3346	}
3347
3348	impl<'a, K, V, S, A: Allocator> RawEntryMut<'a, K, V, S, A> {
3349	/// Sets the value of the entry, and returns a RawOccupiedEntryMut.
3350	///
3351	/// # Examples
3352	///
3353	/// ```
3354	/// use hashbrown::HashMap;
3355	///
3356	/// let mut map: HashMap<&str, u32> = HashMap::new();
3357	/// let entry = map.raw_entry_mut().from_key("horseyland").insert("horseyland", `37`);
3358	///
3359	/// assert_eq!(entry.remove_entry(), ("horseyland", `37`));
3360	/// ```
3361	#[cfg_attr(feature = "inline-more", inline)]
3362	pub fn insert(self, key: K, value: V) -> RawOccupiedEntryMut<'a, K, V, S, A>
3363	where
3364	K: Hash,
3365	S: BuildHasher,
3366	{
3367	match self {
3368	RawEntryMut::Occupied(mut entry) => {
3369	entry.insert(value);
3370	entry
3371	}
3372	RawEntryMut::Vacant(entry) => entry.insert_entry(key, value),
3373	}
3374	}
3375
3376	/// Ensures a value is in the entry by inserting the default if empty, and returns
3377	/// mutable references to the key and value in the entry.
3378	///
3379	/// # Examples
3380	///
3381	/// ```
3382	/// use hashbrown::HashMap;
3383	///
3384	/// let mut map: HashMap<&str, u32> = HashMap::new();
3385	///
3386	/// map.raw_entry_mut().from_key("poneyland").or_insert("poneyland", `3`);
3387	/// assert_eq!(map["poneyland"], `3`);
3388	///
3389	/// map.raw_entry_mut().from_key("poneyland").or_insert("poneyland", `10`).1 = `2`;
3390	/// assert_eq!(map["poneyland"], `6`);
3391	/// ```
3392	#[cfg_attr(feature = "inline-more", inline)]
3393	pub fn or_insert(self, default_key: K, default_val: V) -> (&'a mut K, &'a mut V)
3394	where
3395	K: Hash,
3396	S: BuildHasher,
3397	{
3398	match self {
3399	RawEntryMut::Occupied(entry) => entry.into_key_value(),
3400	RawEntryMut::Vacant(entry) => entry.insert(default_key, default_val),
3401	}
3402	}
3403
3404	/// Ensures a value is in the entry by inserting the result of the default function if empty,
3405	/// and returns mutable references to the key and value in the entry.
3406	///
3407	/// # Examples
3408	///
3409	/// ```
3410	/// use hashbrown::HashMap;
3411	///
3412	/// let mut map: HashMap<&str, String> = HashMap::new();
3413	///
3414	/// map.raw_entry_mut().from_key("poneyland").or_insert_with(\|\| {
3415	/// ("poneyland", "hoho".to_string())
3416	/// });
3417	///
3418	/// assert_eq!(map["poneyland"], "hoho".to_string());
3419	/// ```
3420	#[cfg_attr(feature = "inline-more", inline)]
3421	pub fn or_insert_with<F>(self, default: F) -> (&'a mut K, &'a mut V)
3422	where
3423	F: FnOnce() -> (K, V),
3424	K: Hash,
3425	S: BuildHasher,
3426	{
3427	match self {
3428	RawEntryMut::Occupied(entry) => entry.into_key_value(),
3429	RawEntryMut::Vacant(entry) => {
3430	let (k, v) = default();
3431	entry.insert(k, v)
3432	}
3433	}
3434	}
3435
3436	/// Provides in-place mutable access to an occupied entry before any
3437	/// potential inserts into the map.
3438	///
3439	/// # Examples
3440	///
3441	/// ```
3442	/// use hashbrown::HashMap;
3443	///
3444	/// let mut map: HashMap<&str, u32> = HashMap::new();
3445	///
3446	/// map.raw_entry_mut()
3447	/// .from_key("poneyland")
3448	/// .and_modify(\|_k, v\| { *v += `1` })
3449	/// .or_insert("poneyland", `42`);
3450	/// assert_eq!(map["poneyland"], `42`);
3451	///
3452	/// map.raw_entry_mut()
3453	/// .from_key("poneyland")
3454	/// .and_modify(\|_k, v\| { *v += `1` })
3455	/// .or_insert("poneyland", `0`);
3456	/// assert_eq!(map["poneyland"], `43`);
3457	/// ```
3458	#[cfg_attr(feature = "inline-more", inline)]
3459	pub fn and_modify<F>(self, f: F) -> Self
3460	where
3461	F: FnOnce(&mut K, &mut V),
3462	{
3463	match self {
3464	RawEntryMut::Occupied(mut entry) => {
3465	{
3466	let (k, v) = entry.get_key_value_mut();
3467	f(k, v);
3468	}
3469	RawEntryMut::Occupied(entry)
3470	}
3471	RawEntryMut::Vacant(entry) => RawEntryMut::Vacant(entry),
3472	}
3473	}
3474
3475	/// Provides shared access to the key and owned access to the value of
3476	/// an occupied entry and allows to replace or remove it based on the
3477	/// value of the returned option.
3478	///
3479	/// # Examples
3480	///
3481	/// ```
3482	/// use hashbrown::HashMap;
3483	/// use hashbrown::hash_map::RawEntryMut;
3484	///
3485	/// let mut map: HashMap<&str, u32> = HashMap::new();
3486	///
3487	/// let entry = map
3488	/// .raw_entry_mut()
3489	/// .from_key("poneyland")
3490	/// .and_replace_entry_with(\|_k, _v\| panic!());
3491	///
3492	/// match entry {
3493	/// RawEntryMut::Vacant(_) => {},
3494	/// RawEntryMut::Occupied(_) => panic!(),
3495	/// }
3496	///
3497	/// map.insert("poneyland", `42`);
3498	///
3499	/// let entry = map
3500	/// .raw_entry_mut()
3501	/// .from_key("poneyland")
3502	/// .and_replace_entry_with(\|k, v\| {
3503	/// assert_eq!(k, &"poneyland");
3504	/// assert_eq!(v, `42`);
3505	/// Some(v + `1`)
3506	/// });
3507	///
3508	/// match entry {
3509	/// RawEntryMut::Occupied(e) => {
3510	/// assert_eq!(e.key(), &"poneyland");
3511	/// assert_eq!(e.get(), &`43`);
3512	/// },
3513	/// RawEntryMut::Vacant(_) => panic!(),
3514	/// }
3515	///
3516	/// assert_eq!(map["poneyland"], `43`);
3517	///
3518	/// let entry = map
3519	/// .raw_entry_mut()
3520	/// .from_key("poneyland")
3521	/// .and_replace_entry_with(\|_k, _v\| None);
3522	///
3523	/// match entry {
3524	/// RawEntryMut::Vacant(_) => {},
3525	/// RawEntryMut::Occupied(_) => panic!(),
3526	/// }
3527	///
3528	/// assert!(!map.contains_key("poneyland"));
3529	/// ```
3530	#[cfg_attr(feature = "inline-more", inline)]
3531	pub fn and_replace_entry_with<F>(self, f: F) -> Self
3532	where
3533	F: FnOnce(&K, V) -> Option<V>,
3534	{
3535	match self {
3536	RawEntryMut::Occupied(entry) => entry.replace_entry_with(f),
3537	RawEntryMut::Vacant(_) => self,
3538	}
3539	}
3540	}
3541
3542	impl<'a, K, V, S, A: Allocator> RawOccupiedEntryMut<'a, K, V, S, A> {
3543	/// Gets a reference to the key in the entry.
3544	///
3545	/// # Examples
3546	///
3547	/// ```
3548	/// use hashbrown::hash_map::{HashMap, RawEntryMut};
3549	///
3550	/// let mut map: HashMap<&str, u32> = [("a", `100`), ("b", `200`)].into();
3551	///
3552	/// match map.raw_entry_mut().from_key(&"a") {
3553	/// RawEntryMut::Vacant(_) => panic!(),
3554	/// RawEntryMut::Occupied(o) => assert_eq!(o.key(), &"a")
3555	/// }
3556	/// ```
3557	#[cfg_attr(feature = "inline-more", inline)]
3558	pub fn key(&self) -> &K {
3559	unsafe { &self.elem.as_ref().0 }
3560	}
3561
3562	/// Gets a mutable reference to the key in the entry.
3563	///
3564	/// # Examples
3565	///
3566	/// ```
3567	/// use hashbrown::hash_map::{HashMap, RawEntryMut};
3568	/// use std::rc::Rc;
3569	///
3570	/// let key_one = Rc::new("a");
3571	/// let key_two = Rc::new("a");
3572	///
3573	/// let mut map: HashMap<Rc<&str>, u32> = HashMap::new();
3574	/// map.insert(key_one.clone(), `10`);
3575	///
3576	/// assert_eq!(map[&key_one], `10`);
3577	/// assert!(Rc::strong_count(&key_one) == `2` && Rc::strong_count(&key_two) == `1`);
3578	///
3579	/// match map.raw_entry_mut().from_key(&key_one) {
3580	/// RawEntryMut::Vacant(_) => panic!(),
3581	/// RawEntryMut::Occupied(mut o) => {
3582	/// *o.key_mut() = key_two.clone();
3583	/// }
3584	/// }
3585	/// assert_eq!(map[&key_two], `10`);
3586	/// assert!(Rc::strong_count(&key_one) == `1` && Rc::strong_count(&key_two) == `2`);
3587	/// ```
3588	#[cfg_attr(feature = "inline-more", inline)]
3589	pub fn key_mut(&mut self) -> &mut K {
3590	unsafe { &mut self.elem.as_mut().0 }
3591	}
3592
3593	/// Converts the entry into a mutable reference to the key in the entry
3594	/// with a lifetime bound to the map itself.
3595	///
3596	/// # Examples
3597	///
3598	/// ```
3599	/// use hashbrown::hash_map::{HashMap, RawEntryMut};
3600	/// use std::rc::Rc;
3601	///
3602	/// let key_one = Rc::new("a");
3603	/// let key_two = Rc::new("a");
3604	///
3605	/// let mut map: HashMap<Rc<&str>, u32> = HashMap::new();
3606	/// map.insert(key_one.clone(), `10`);
3607	///
3608	/// assert_eq!(map[&key_one], `10`);
3609	/// assert!(Rc::strong_count(&key_one) == `2` && Rc::strong_count(&key_two) == `1`);
3610	///
3611	/// let inside_key: &mut Rc<&str>;
3612	///
3613	/// match map.raw_entry_mut().from_key(&key_one) {
3614	/// RawEntryMut::Vacant(_) => panic!(),
3615	/// RawEntryMut::Occupied(o) => inside_key = o.into_key(),
3616	/// }
3617	/// *inside_key = key_two.clone();
3618	///
3619	/// assert_eq!(map[&key_two], `10`);
3620	/// assert!(Rc::strong_count(&key_one) == `1` && Rc::strong_count(&key_two) == `2`);
3621	/// ```
3622	#[cfg_attr(feature = "inline-more", inline)]
3623	pub fn into_key(self) -> &'a mut K {
3624	unsafe { &mut self.elem.as_mut().0 }
3625	}
3626
3627	/// Gets a reference to the value in the entry.
3628	///
3629	/// # Examples
3630	///
3631	/// ```
3632	/// use hashbrown::hash_map::{HashMap, RawEntryMut};
3633	///
3634	/// let mut map: HashMap<&str, u32> = [("a", `100`), ("b", `200`)].into();
3635	///
3636	/// match map.raw_entry_mut().from_key(&"a") {
3637	/// RawEntryMut::Vacant(_) => panic!(),
3638	/// RawEntryMut::Occupied(o) => assert_eq!(o.get(), &`100`),
3639	/// }
3640	/// ```
3641	#[cfg_attr(feature = "inline-more", inline)]
3642	pub fn get(&self) -> &V {
3643	unsafe { &self.elem.as_ref().1 }
3644	}
3645
3646	/// Converts the OccupiedEntry into a mutable reference to the value in the entry
3647	/// with a lifetime bound to the map itself.
3648	///
3649	/// # Examples
3650	///
3651	/// ```
3652	/// use hashbrown::hash_map::{HashMap, RawEntryMut};
3653	///
3654	/// let mut map: HashMap<&str, u32> = [("a", `100`), ("b", `200`)].into();
3655	///
3656	/// let value: &mut u32;
3657	///
3658	/// match map.raw_entry_mut().from_key(&"a") {
3659	/// RawEntryMut::Vacant(_) => panic!(),
3660	/// RawEntryMut::Occupied(o) => value = o.into_mut(),
3661	/// }
3662	/// *value += `900`;
3663	///
3664	/// assert_eq!(map[&"a"], `1000`);
3665	/// ```
3666	#[cfg_attr(feature = "inline-more", inline)]
3667	pub fn into_mut(self) -> &'a mut V {
3668	unsafe { &mut self.elem.as_mut().1 }
3669	}
3670
3671	/// Gets a mutable reference to the value in the entry.
3672	///
3673	/// # Examples
3674	///
3675	/// ```
3676	/// use hashbrown::hash_map::{HashMap, RawEntryMut};
3677	///
3678	/// let mut map: HashMap<&str, u32> = [("a", `100`), ("b", `200`)].into();
3679	///
3680	/// match map.raw_entry_mut().from_key(&"a") {
3681	/// RawEntryMut::Vacant(_) => panic!(),
3682	/// RawEntryMut::Occupied(mut o) => *o.get_mut() += `900`,
3683	/// }
3684	///
3685	/// assert_eq!(map[&"a"], `1000`);
3686	/// ```
3687	#[cfg_attr(feature = "inline-more", inline)]
3688	pub fn get_mut(&mut self) -> &mut V {
3689	unsafe { &mut self.elem.as_mut().1 }
3690	}
3691
3692	/// Gets a reference to the key and value in the entry.
3693	///
3694	/// # Examples
3695	///
3696	/// ```
3697	/// use hashbrown::hash_map::{HashMap, RawEntryMut};
3698	///
3699	/// let mut map: HashMap<&str, u32> = [("a", `100`), ("b", `200`)].into();
3700	///
3701	/// match map.raw_entry_mut().from_key(&"a") {
3702	/// RawEntryMut::Vacant(_) => panic!(),
3703	/// RawEntryMut::Occupied(o) => assert_eq!(o.get_key_value(), (&"a", &`100`)),
3704	/// }
3705	/// ```
3706	#[cfg_attr(feature = "inline-more", inline)]
3707	pub fn get_key_value(&self) -> (&K, &V) {
3708	unsafe {
3709	let (key, value) = self.elem.as_ref();
3710	(key, value)
3711	}
3712	}
3713
3714	/// Gets a mutable reference to the key and value in the entry.
3715	///
3716	/// # Examples
3717	///
3718	/// ```
3719	/// use hashbrown::hash_map::{HashMap, RawEntryMut};
3720	/// use std::rc::Rc;
3721	///
3722	/// let key_one = Rc::new("a");
3723	/// let key_two = Rc::new("a");
3724	///
3725	/// let mut map: HashMap<Rc<&str>, u32> = HashMap::new();
3726	/// map.insert(key_one.clone(), `10`);
3727	///
3728	/// assert_eq!(map[&key_one], `10`);
3729	/// assert!(Rc::strong_count(&key_one) == `2` && Rc::strong_count(&key_two) == `1`);
3730	///
3731	/// match map.raw_entry_mut().from_key(&key_one) {
3732	/// RawEntryMut::Vacant(_) => panic!(),
3733	/// RawEntryMut::Occupied(mut o) => {
3734	/// let (inside_key, inside_value) = o.get_key_value_mut();
3735	/// *inside_key = key_two.clone();
3736	/// *inside_value = `100`;
3737	/// }
3738	/// }
3739	/// assert_eq!(map[&key_two], `100`);
3740	/// assert!(Rc::strong_count(&key_one) == `1` && Rc::strong_count(&key_two) == `2`);
3741	/// ```
3742	#[cfg_attr(feature = "inline-more", inline)]
3743	pub fn get_key_value_mut(&mut self) -> (&mut K, &mut V) {
3744	unsafe {
3745	let &mut (ref mut key, ref mut value) = self.elem.as_mut();
3746	(key, value)
3747	}
3748	}
3749
3750	/// Converts the OccupiedEntry into a mutable reference to the key and value in the entry
3751	/// with a lifetime bound to the map itself.
3752	///
3753	/// # Examples
3754	///
3755	/// ```
3756	/// use hashbrown::hash_map::{HashMap, RawEntryMut};
3757	/// use std::rc::Rc;
3758	///
3759	/// let key_one = Rc::new("a");
3760	/// let key_two = Rc::new("a");
3761	///
3762	/// let mut map: HashMap<Rc<&str>, u32> = HashMap::new();
3763	/// map.insert(key_one.clone(), `10`);
3764	///
3765	/// assert_eq!(map[&key_one], `10`);
3766	/// assert!(Rc::strong_count(&key_one) == `2` && Rc::strong_count(&key_two) == `1`);
3767	///
3768	/// let inside_key: &mut Rc<&str>;
3769	/// let inside_value: &mut u32;
3770	/// match map.raw_entry_mut().from_key(&key_one) {
3771	/// RawEntryMut::Vacant(_) => panic!(),
3772	/// RawEntryMut::Occupied(o) => {
3773	/// let tuple = o.into_key_value();
3774	/// inside_key = tuple.0;
3775	/// inside_value = tuple.1;
3776	/// }
3777	/// }
3778	/// *inside_key = key_two.clone();
3779	/// *inside_value = `100`;
3780	/// assert_eq!(map[&key_two], `100`);
3781	/// assert!(Rc::strong_count(&key_one) == `1` && Rc::strong_count(&key_two) == `2`);
3782	/// ```
3783	#[cfg_attr(feature = "inline-more", inline)]
3784	pub fn into_key_value(self) -> (&'a mut K, &'a mut V) {
3785	unsafe {
3786	let &mut (ref mut key, ref mut value) = self.elem.as_mut();
3787	(key, value)
3788	}
3789	}
3790
3791	/// Sets the value of the entry, and returns the entry's old value.
3792	///
3793	/// # Examples
3794	///
3795	/// ```
3796	/// use hashbrown::hash_map::{HashMap, RawEntryMut};
3797	///
3798	/// let mut map: HashMap<&str, u32> = [("a", `100`), ("b", `200`)].into();
3799	///
3800	/// match map.raw_entry_mut().from_key(&"a") {
3801	/// RawEntryMut::Vacant(_) => panic!(),
3802	/// RawEntryMut::Occupied(mut o) => assert_eq!(o.insert(`1000`), `100`),
3803	/// }
3804	///
3805	/// assert_eq!(map[&"a"], `1000`);
3806	/// ```
3807	#[cfg_attr(feature = "inline-more", inline)]
3808	pub fn insert(&mut self, value: V) -> V {
3809	mem::replace(self.get_mut(), value)
3810	}
3811
3812	/// Sets the value of the entry, and returns the entry's old value.
3813	///
3814	/// # Examples
3815	///
3816	/// ```
3817	/// use hashbrown::hash_map::{HashMap, RawEntryMut};
3818	/// use std::rc::Rc;
3819	///
3820	/// let key_one = Rc::new("a");
3821	/// let key_two = Rc::new("a");
3822	///
3823	/// let mut map: HashMap<Rc<&str>, u32> = HashMap::new();
3824	/// map.insert(key_one.clone(), `10`);
3825	///
3826	/// assert_eq!(map[&key_one], `10`);
3827	/// assert!(Rc::strong_count(&key_one) == `2` && Rc::strong_count(&key_two) == `1`);
3828	///
3829	/// match map.raw_entry_mut().from_key(&key_one) {
3830	/// RawEntryMut::Vacant(_) => panic!(),
3831	/// RawEntryMut::Occupied(mut o) => {
3832	/// let old_key = o.insert_key(key_two.clone());
3833	/// assert!(Rc::ptr_eq(&old_key, &key_one));
3834	/// }
3835	/// }
3836	/// assert_eq!(map[&key_two], `10`);
3837	/// assert!(Rc::strong_count(&key_one) == `1` && Rc::strong_count(&key_two) == `2`);
3838	/// ```
3839	#[cfg_attr(feature = "inline-more", inline)]
3840	pub fn insert_key(&mut self, key: K) -> K {
3841	mem::replace(self.key_mut(), key)
3842	}
3843
3844	/// Takes the value out of the entry, and returns it.
3845	///
3846	/// # Examples
3847	///
3848	/// ```
3849	/// use hashbrown::hash_map::{HashMap, RawEntryMut};
3850	///
3851	/// let mut map: HashMap<&str, u32> = [("a", `100`), ("b", `200`)].into();
3852	///
3853	/// match map.raw_entry_mut().from_key(&"a") {
3854	/// RawEntryMut::Vacant(_) => panic!(),
3855	/// RawEntryMut::Occupied(o) => assert_eq!(o.remove(), `100`),
3856	/// }
3857	/// assert_eq!(map.get(&"a"), None);
3858	/// ```
3859	#[cfg_attr(feature = "inline-more", inline)]
3860	pub fn remove(self) -> V {
3861	self.remove_entry().1
3862	}
3863
3864	/// Take the ownership of the key and value from the map.
3865	///
3866	/// # Examples
3867	///
3868	/// ```
3869	/// use hashbrown::hash_map::{HashMap, RawEntryMut};
3870	///
3871	/// let mut map: HashMap<&str, u32> = [("a", `100`), ("b", `200`)].into();
3872	///
3873	/// match map.raw_entry_mut().from_key(&"a") {
3874	/// RawEntryMut::Vacant(_) => panic!(),
3875	/// RawEntryMut::Occupied(o) => assert_eq!(o.remove_entry(), ("a", `100`)),
3876	/// }
3877	/// assert_eq!(map.get(&"a"), None);
3878	/// ```
3879	#[cfg_attr(feature = "inline-more", inline)]
3880	pub fn remove_entry(self) -> (K, V) {
3881	unsafe { self.table.remove(self.elem).0 }
3882	}
3883
3884	/// Provides shared access to the key and owned access to the value of
3885	/// the entry and allows to replace or remove it based on the
3886	/// value of the returned option.
3887	///
3888	/// # Examples
3889	///
3890	/// ```
3891	/// use hashbrown::hash_map::{HashMap, RawEntryMut};
3892	///
3893	/// let mut map: HashMap<&str, u32> = [("a", `100`), ("b", `200`)].into();
3894	///
3895	/// let raw_entry = match map.raw_entry_mut().from_key(&"a") {
3896	/// RawEntryMut::Vacant(_) => panic!(),
3897	/// RawEntryMut::Occupied(o) => o.replace_entry_with(\|k, v\| {
3898	/// assert_eq!(k, &"a");
3899	/// assert_eq!(v, `100`);
3900	/// Some(v + `900`)
3901	/// }),
3902	/// };
3903	/// let raw_entry = match raw_entry {
3904	/// RawEntryMut::Vacant(_) => panic!(),
3905	/// RawEntryMut::Occupied(o) => o.replace_entry_with(\|k, v\| {
3906	/// assert_eq!(k, &"a");
3907	/// assert_eq!(v, `1000`);
3908	/// None
3909	/// }),
3910	/// };
3911	/// match raw_entry {
3912	/// RawEntryMut::Vacant(_) => { },
3913	/// RawEntryMut::Occupied(_) => panic!(),
3914	/// };
3915	/// assert_eq!(map.get(&"a"), None);
3916	/// ```
3917	#[cfg_attr(feature = "inline-more", inline)]
3918	pub fn replace_entry_with<F>(self, f: F) -> RawEntryMut<'a, K, V, S, A>
3919	where
3920	F: FnOnce(&K, V) -> Option<V>,
3921	{
3922	unsafe {
3923	let still_occupied = self
3924	.table
3925	.replace_bucket_with(self.elem.clone(), \|(key, value)\| {
3926	f(&key, value).map(\|new_value\| (key, new_value))
3927	});
3928
3929	if still_occupied {
3930	RawEntryMut::Occupied(self)
3931	} else {
3932	RawEntryMut::Vacant(RawVacantEntryMut {
3933	table: self.table,
3934	hash_builder: self.hash_builder,
3935	})
3936	}
3937	}
3938	}
3939	}
3940
3941	impl<'a, K, V, S, A: Allocator> RawVacantEntryMut<'a, K, V, S, A> {
3942	/// Sets the value of the entry with the VacantEntry's key,
3943	/// and returns a mutable reference to it.
3944	///
3945	/// # Examples
3946	///
3947	/// ```
3948	/// use hashbrown::hash_map::{HashMap, RawEntryMut};
3949	///
3950	/// let mut map: HashMap<&str, u32> = [("a", `100`), ("b", `200`)].into();
3951	///
3952	/// match map.raw_entry_mut().from_key(&"c") {
3953	/// RawEntryMut::Occupied(_) => panic!(),
3954	/// RawEntryMut::Vacant(v) => assert_eq!(v.insert("c", `300`), (&mut "c", &mut `300`)),
3955	/// }
3956	///
3957	/// assert_eq!(map[&"c"], `300`);
3958	/// ```
3959	#[cfg_attr(feature = "inline-more", inline)]
3960	pub fn insert(self, key: K, value: V) -> (&'a mut K, &'a mut V)
3961	where
3962	K: Hash,
3963	S: BuildHasher,
3964	{
3965	let hash = make_hash::<K, S>(self.hash_builder, &key);
3966	self.insert_hashed_nocheck(hash, key, value)
3967	}
3968
3969	/// Sets the value of the entry with the VacantEntry's key,
3970	/// and returns a mutable reference to it.
3971	///
3972	/// # Examples
3973	///
3974	/// ```
3975	/// use core::hash::{BuildHasher, Hash};
3976	/// use hashbrown::hash_map::{HashMap, RawEntryMut};
3977	///
3978	/// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
3979	/// use core::hash::Hasher;
3980	/// let mut state = hash_builder.build_hasher();
3981	/// key.hash(&mut state);
3982	/// state.finish()
3983	/// }
3984	///
3985	/// let mut map: HashMap<&str, u32> = [("a", `100`), ("b", `200`)].into();
3986	/// let key = "c";
3987	/// let hash = compute_hash(map.hasher(), &key);
3988	///
3989	/// match map.raw_entry_mut().from_key_hashed_nocheck(hash, &key) {
3990	/// RawEntryMut::Occupied(_) => panic!(),
3991	/// RawEntryMut::Vacant(v) => assert_eq!(
3992	/// v.insert_hashed_nocheck(hash, key, `300`),
3993	/// (&mut "c", &mut `300`)
3994	/// ),
3995	/// }
3996	///
3997	/// assert_eq!(map[&"c"], `300`);
3998	/// ```
3999	#[cfg_attr(feature = "inline-more", inline)]
4000	#[allow(clippy::shadow_unrelated)]
4001	pub fn insert_hashed_nocheck(self, hash: u64, key: K, value: V) -> (&'a mut K, &'a mut V)
4002	where
4003	K: Hash,
4004	S: BuildHasher,
4005	{
4006	let &mut (ref mut k, ref mut v) = self.table.insert_entry(
4007	hash,
4008	(key, value),
4009	make_hasher::<_, V, S>(self.hash_builder),
4010	);
4011	(k, v)
4012	}
4013
4014	/// Set the value of an entry with a custom hasher function.
4015	///
4016	/// # Examples
4017	///
4018	/// ```
4019	/// use core::hash::{BuildHasher, Hash};
4020	/// use hashbrown::hash_map::{HashMap, RawEntryMut};
4021	///
4022	/// fn make_hasher<K, S>(hash_builder: &S) -> impl Fn(&K) -> u64 + '_
4023	/// where
4024	/// K: Hash + ?Sized,
4025	/// S: BuildHasher,
4026	/// {
4027	/// move \|key: &K\| {
4028	/// use core::hash::Hasher;
4029	/// let mut state = hash_builder.build_hasher();
4030	/// key.hash(&mut state);
4031	/// state.finish()
4032	/// }
4033	/// }
4034	///
4035	/// let mut map: HashMap<&str, u32> = HashMap::new();
4036	/// let key = "a";
4037	/// let hash_builder = map.hasher().clone();
4038	/// let hash = make_hasher(&hash_builder)(&key);
4039	///
4040	/// match map.raw_entry_mut().from_hash(hash, \|q\| q == &key) {
4041	/// RawEntryMut::Occupied(_) => panic!(),
4042	/// RawEntryMut::Vacant(v) => assert_eq!(
4043	/// v.insert_with_hasher(hash, key, `100`, make_hasher(&hash_builder)),
4044	/// (&mut "a", &mut `100`)
4045	/// ),
4046	/// }
4047	/// map.extend([("b", `200`), ("c", `300`), ("d", `400`), ("e", `500`), ("f", `600`)]);
4048	/// assert_eq!(map[&"a"], `100`);
4049	/// ```
4050	#[cfg_attr(feature = "inline-more", inline)]
4051	pub fn insert_with_hasher<H>(
4052	self,
4053	hash: u64,
4054	key: K,
4055	value: V,
4056	hasher: H,
4057	) -> (&'a mut K, &'a mut V)
4058	where
4059	H: Fn(&K) -> u64,
4060	{
4061	let &mut (ref mut k, ref mut v) = self
4062	.table
4063	.insert_entry(hash, (key, value), \|x\| hasher(&x.0));
4064	(k, v)
4065	}
4066
4067	#[cfg_attr(feature = "inline-more", inline)]
4068	fn insert_entry(self, key: K, value: V) -> RawOccupiedEntryMut<'a, K, V, S, A>
4069	where
4070	K: Hash,
4071	S: BuildHasher,
4072	{
4073	let hash = make_hash::<K, S>(self.hash_builder, &key);
4074	let elem = self.table.insert(
4075	hash,
4076	(key, value),
4077	make_hasher::<_, V, S>(self.hash_builder),
4078	);
4079	RawOccupiedEntryMut {
4080	elem,
4081	table: self.table,
4082	hash_builder: self.hash_builder,
4083	}
4084	}
4085	}
4086
4087	impl<K, V, S, A: Allocator> Debug for RawEntryBuilderMut<'_, K, V, S, A> {
4088	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4089	f.debug_struct(name:"RawEntryBuilder").finish()
4090	}
4091	}
4092
4093	impl<K: Debug, V: Debug, S, A: Allocator> Debug for RawEntryMut<'_, K, V, S, A> {
4094	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4095	match *self {
4096	RawEntryMut::Vacant(ref v: &RawVacantEntryMut<'_, K, …, …, …>) => f.debug_tuple(name:"RawEntry").field(v).finish(),
4097	RawEntryMut::Occupied(ref o: &RawOccupiedEntryMut<'_, K, …, …, …>) => f.debug_tuple(name:"RawEntry").field(o).finish(),
4098	}
4099	}
4100	}
4101
4102	impl<K: Debug, V: Debug, S, A: Allocator> Debug for RawOccupiedEntryMut<'_, K, V, S, A> {
4103	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4104	f&mut DebugStruct<'_, '_>.debug_struct("RawOccupiedEntryMut")
4105	.field("key", self.key())
4106	.field(name:"value", self.get())
4107	.finish()
4108	}
4109	}
4110
4111	impl<K, V, S, A: Allocator> Debug for RawVacantEntryMut<'_, K, V, S, A> {
4112	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4113	f.debug_struct(name:"RawVacantEntryMut").finish()
4114	}
4115	}
4116
4117	impl<K, V, S, A: Allocator> Debug for RawEntryBuilder<'_, K, V, S, A> {
4118	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4119	f.debug_struct(name:"RawEntryBuilder").finish()
4120	}
4121	}
4122
4123	/// A view into a single entry in a map, which may either be vacant or occupied.
4124	///
4125	/// This `enum` is constructed from the [`entry`] method on [`HashMap`].
4126	///
4127	/// [`HashMap`]: struct.HashMap.html
4128	/// [`entry`]: struct.HashMap.html#method.entry
4129	///
4130	/// # Examples
4131	///
4132	/// ```
4133	/// use hashbrown::hash_map::{Entry, HashMap, OccupiedEntry};
4134	///
4135	/// let mut map = HashMap::new();
4136	/// map.extend([("a", `10`), ("b", `20`), ("c", `30`)]);
4137	/// assert_eq!(map.len(), `3`);
4138	///
4139	/// // Existing key (insert)
4140	/// let entry: Entry<_, _, _> = map.entry("a");
4141	/// let _raw_o: OccupiedEntry<_, _, _> = entry.insert(`1`);
4142	/// assert_eq!(map.len(), `3`);
4143	/// // Nonexistent key (insert)
4144	/// map.entry("d").insert(`4`);
4145	///
4146	/// // Existing key (or_insert)
4147	/// let v = map.entry("b").or_insert(`2`);
4148	/// assert_eq!(std::mem::replace(v, `2`), `20`);
4149	/// // Nonexistent key (or_insert)
4150	/// map.entry("e").or_insert(`5`);
4151	///
4152	/// // Existing key (or_insert_with)
4153	/// let v = map.entry("c").or_insert_with(\|\| `3`);
4154	/// assert_eq!(std::mem::replace(v, `3`), `30`);
4155	/// // Nonexistent key (or_insert_with)
4156	/// map.entry("f").or_insert_with(\|\| `6`);
4157	///
4158	/// println!("Our HashMap: {:?}", map);
4159	///
4160	/// let mut vec: Vec<_> = map.iter().map(\|(&k, &v)\| (k, v)).collect();
4161	/// // The `Iter` iterator produces items in arbitrary order, so the
4162	/// // items must be sorted to test them against a sorted array.
4163	/// vec.sort_unstable();
4164	/// assert_eq!(vec, [("a", `1`), ("b", `2`), ("c", `3`), ("d", `4`), ("e", `5`), ("f", `6`)]);
4165	/// ```
4166	pub enum Entry<'a, K, V, S, A = Global>
4167	where
4168	A: Allocator,
4169	{
4170	/// An occupied entry.
4171	///
4172	/// # Examples
4173	///
4174	/// ```
4175	/// use hashbrown::hash_map::{Entry, HashMap};
4176	/// let mut map: HashMap<_, _> = [("a", `100`), ("b", `200`)].into();
4177	///
4178	/// match map.entry("a") {
4179	/// Entry::Vacant(_) => unreachable!(),
4180	/// Entry::Occupied(_) => { }
4181	/// }
4182	/// ```
4183	Occupied(OccupiedEntry<'a, K, V, S, A>),
4184
4185	/// A vacant entry.
4186	///
4187	/// # Examples
4188	///
4189	/// ```
4190	/// use hashbrown::hash_map::{Entry, HashMap};
4191	/// let mut map: HashMap<&str, i32> = HashMap::new();
4192	///
4193	/// match map.entry("a") {
4194	/// Entry::Occupied(_) => unreachable!(),
4195	/// Entry::Vacant(_) => { }
4196	/// }
4197	/// ```
4198	Vacant(VacantEntry<'a, K, V, S, A>),
4199	}
4200
4201	impl<K: Debug, V: Debug, S, A: Allocator> Debug for Entry<'_, K, V, S, A> {
4202	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4203	match *self {
4204	Entry::Vacant(ref v: &VacantEntry<'_, K, V, S, …>) => f.debug_tuple(name:"Entry").field(v).finish(),
4205	Entry::Occupied(ref o: &OccupiedEntry<'_, K, V, S, …>) => f.debug_tuple(name:"Entry").field(o).finish(),
4206	}
4207	}
4208	}
4209
4210	/// A view into an occupied entry in a `HashMap`.
4211	/// It is part of the [`Entry`] enum.
4212	///
4213	/// [`Entry`]: enum.Entry.html
4214	///
4215	/// # Examples
4216	///
4217	/// ```
4218	/// use hashbrown::hash_map::{Entry, HashMap, OccupiedEntry};
4219	///
4220	/// let mut map = HashMap::new();
4221	/// map.extend([("a", `10`), ("b", `20`), ("c", `30`)]);
4222	///
4223	/// let _entry_o: OccupiedEntry<_, _, _> = map.entry("a").insert(`100`);
4224	/// assert_eq!(map.len(), `3`);
4225	///
4226	/// // Existing key (insert and update)
4227	/// match map.entry("a") {
4228	/// Entry::Vacant(_) => unreachable!(),
4229	/// Entry::Occupied(mut view) => {
4230	/// assert_eq!(view.get(), &`100`);
4231	/// let v = view.get_mut();
4232	/// v = `10`;
4233	/// assert_eq!(view.insert(`1111`), `1000`);
4234	/// }
4235	/// }
4236	///
4237	/// assert_eq!(map[&"a"], `1111`);
4238	/// assert_eq!(map.len(), `3`);
4239	///
4240	/// // Existing key (take)
4241	/// match map.entry("c") {
4242	/// Entry::Vacant(_) => unreachable!(),
4243	/// Entry::Occupied(view) => {
4244	/// assert_eq!(view.remove_entry(), ("c", `30`));
4245	/// }
4246	/// }
4247	/// assert_eq!(map.get(&"c"), None);
4248	/// assert_eq!(map.len(), `2`);
4249	/// ```
4250	pub struct OccupiedEntry<'a, K, V, S = DefaultHashBuilder, A: Allocator = Global> {
4251	hash: u64,
4252	key: Option<K>,
4253	elem: Bucket<(K, V)>,
4254	table: &'a mut HashMap<K, V, S, A>,
4255	}
4256
4257	unsafe impl<K, V, S, A> Send for OccupiedEntry<'_, K, V, S, A>
4258	where
4259	K: Send,
4260	V: Send,
4261	S: Send,
4262	A: Send + Allocator,
4263	{
4264	}
4265	unsafe impl<K, V, S, A> Sync for OccupiedEntry<'_, K, V, S, A>
4266	where
4267	K: Sync,
4268	V: Sync,
4269	S: Sync,
4270	A: Sync + Allocator,
4271	{
4272	}
4273
4274	impl<K: Debug, V: Debug, S, A: Allocator> Debug for OccupiedEntry<'_, K, V, S, A> {
4275	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4276	f&mut DebugStruct<'_, '_>.debug_struct("OccupiedEntry")
4277	.field("key", self.key())
4278	.field(name:"value", self.get())
4279	.finish()
4280	}
4281	}
4282
4283	/// A view into a vacant entry in a `HashMap`.
4284	/// It is part of the [`Entry`] enum.
4285	///
4286	/// [`Entry`]: enum.Entry.html
4287	///
4288	/// # Examples
4289	///
4290	/// ```
4291	/// use hashbrown::hash_map::{Entry, HashMap, VacantEntry};
4292	///
4293	/// let mut map = HashMap::<&str, i32>::new();
4294	///
4295	/// let entry_v: VacantEntry<_, _, _> = match map.entry("a") {
4296	/// Entry::Vacant(view) => view,
4297	/// Entry::Occupied(_) => unreachable!(),
4298	/// };
4299	/// entry_v.insert(`10`);
4300	/// assert!(map[&"a"] == `10` && map.len() == `1`);
4301	///
4302	/// // Nonexistent key (insert and update)
4303	/// match map.entry("b") {
4304	/// Entry::Occupied(_) => unreachable!(),
4305	/// Entry::Vacant(view) => {
4306	/// let value = view.insert(`2`);
4307	/// assert_eq!(*value, `2`);
4308	/// *value = `20`;
4309	/// }
4310	/// }
4311	/// assert!(map[&"b"] == `20` && map.len() == `2`);
4312	/// ```
4313	pub struct VacantEntry<'a, K, V, S = DefaultHashBuilder, A: Allocator = Global> {
4314	hash: u64,
4315	key: K,
4316	table: &'a mut HashMap<K, V, S, A>,
4317	}
4318
4319	impl<K: Debug, V, S, A: Allocator> Debug for VacantEntry<'_, K, V, S, A> {
4320	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4321	f.debug_tuple(name:"VacantEntry").field(self.key()).finish()
4322	}
4323	}
4324
4325	/// A view into a single entry in a map, which may either be vacant or occupied,
4326	/// with any borrowed form of the map's key type.
4327	///
4328	///
4329	/// This `enum` is constructed from the [`entry_ref`] method on [`HashMap`].
4330	///
4331	/// [`Hash`] and [`Eq`] on the borrowed form of the map's key type must* match those*
4332	/// for the key type. It also require that key may be constructed from the borrowed
4333	/// form through the [`From`] trait.
4334	///
4335	/// [`HashMap`]: struct.HashMap.html
4336	/// [`entry_ref`]: struct.HashMap.html#method.entry_ref
4337	/// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
4338	/// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
4339	/// [`From`]: https://doc.rust-lang.org/std/convert/trait.From.html
4340	///
4341	/// # Examples
4342	///
4343	/// ```
4344	/// use hashbrown::hash_map::{EntryRef, HashMap, OccupiedEntryRef};
4345	///
4346	/// let mut map = HashMap::new();
4347	/// map.extend([("a".to_owned(), `10`), ("b".into(), `20`), ("c".into(), `30`)]);
4348	/// assert_eq!(map.len(), `3`);
4349	///
4350	/// // Existing key (insert)
4351	/// let key = String::from("a");
4352	/// let entry: EntryRef<_, _, _, _> = map.entry_ref(&key);
4353	/// let _raw_o: OccupiedEntryRef<_, _, _, _> = entry.insert(`1`);
4354	/// assert_eq!(map.len(), `3`);
4355	/// // Nonexistent key (insert)
4356	/// map.entry_ref("d").insert(`4`);
4357	///
4358	/// // Existing key (or_insert)
4359	/// let v = map.entry_ref("b").or_insert(`2`);
4360	/// assert_eq!(std::mem::replace(v, `2`), `20`);
4361	/// // Nonexistent key (or_insert)
4362	/// map.entry_ref("e").or_insert(`5`);
4363	///
4364	/// // Existing key (or_insert_with)
4365	/// let v = map.entry_ref("c").or_insert_with(\|\| `3`);
4366	/// assert_eq!(std::mem::replace(v, `3`), `30`);
4367	/// // Nonexistent key (or_insert_with)
4368	/// map.entry_ref("f").or_insert_with(\|\| `6`);
4369	///
4370	/// println!("Our HashMap: {:?}", map);
4371	///
4372	/// for (key, value) in ["a", "b", "c", "d", "e", "f"].into_iter().zip(`1`..=`6`) {
4373	/// assert_eq!(map[key], value)
4374	/// }
4375	/// assert_eq!(map.len(), `6`);
4376	/// ```
4377	pub enum EntryRef<'a, 'b, K, Q: ?Sized, V, S, A = Global>
4378	where
4379	A: Allocator,
4380	{
4381	/// An occupied entry.
4382	///
4383	/// # Examples
4384	///
4385	/// ```
4386	/// use hashbrown::hash_map::{EntryRef, HashMap};
4387	/// let mut map: HashMap<_, _> = [("a".to_owned(), `100`), ("b".into(), `200`)].into();
4388	///
4389	/// match map.entry_ref("a") {
4390	/// EntryRef::Vacant(_) => unreachable!(),
4391	/// EntryRef::Occupied(_) => { }
4392	/// }
4393	/// ```
4394	Occupied(OccupiedEntryRef<'a, 'b, K, Q, V, S, A>),
4395
4396	/// A vacant entry.
4397	///
4398	/// # Examples
4399	///
4400	/// ```
4401	/// use hashbrown::hash_map::{EntryRef, HashMap};
4402	/// let mut map: HashMap<String, i32> = HashMap::new();
4403	///
4404	/// match map.entry_ref("a") {
4405	/// EntryRef::Occupied(_) => unreachable!(),
4406	/// EntryRef::Vacant(_) => { }
4407	/// }
4408	/// ```
4409	Vacant(VacantEntryRef<'a, 'b, K, Q, V, S, A>),
4410	}
4411
4412	impl<K: Borrow<Q>, Q: ?Sized + Debug, V: Debug, S, A: Allocator> Debug
4413	for EntryRef<'_, '_, K, Q, V, S, A>
4414	{
4415	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4416	match *self {
4417	EntryRef::Vacant(ref v: &VacantEntryRef<'_, '_, K, …, …, …, …>) => f.debug_tuple(name:"EntryRef").field(v).finish(),
4418	EntryRef::Occupied(ref o: &OccupiedEntryRef<'_, '_, …, …, …, …, …>) => f.debug_tuple(name:"EntryRef").field(o).finish(),
4419	}
4420	}
4421	}
4422
4423	enum KeyOrRef<'a, K, Q: ?Sized> {
4424	Borrowed(&'a Q),
4425	Owned(K),
4426	}
4427
4428	impl<'a, K, Q: ?Sized> KeyOrRef<'a, K, Q> {
4429	fn into_owned(self) -> K
4430	where
4431	K: From<&'a Q>,
4432	{
4433	match self {
4434	Self::Borrowed(borrowed: &'a Q) => borrowed.into(),
4435	Self::Owned(owned: K) => owned,
4436	}
4437	}
4438	}
4439
4440	impl<'a, K: Borrow<Q>, Q: ?Sized> AsRef<Q> for KeyOrRef<'a, K, Q> {
4441	fn as_ref(&self) -> &Q {
4442	match self {
4443	Self::Borrowed(borrowed: &&'a Q) => borrowed,
4444	Self::Owned(owned: &K) => owned.borrow(),
4445	}
4446	}
4447	}
4448
4449	/// A view into an occupied entry in a `HashMap`.
4450	/// It is part of the [`EntryRef`] enum.
4451	///
4452	/// [`EntryRef`]: enum.EntryRef.html
4453	///
4454	/// # Examples
4455	///
4456	/// ```
4457	/// use hashbrown::hash_map::{EntryRef, HashMap, OccupiedEntryRef};
4458	///
4459	/// let mut map = HashMap::new();
4460	/// map.extend([("a".to_owned(), `10`), ("b".into(), `20`), ("c".into(), `30`)]);
4461	///
4462	/// let key = String::from("a");
4463	/// let _entry_o: OccupiedEntryRef<_, _, _, _> = map.entry_ref(&key).insert(`100`);
4464	/// assert_eq!(map.len(), `3`);
4465	///
4466	/// // Existing key (insert and update)
4467	/// match map.entry_ref("a") {
4468	/// EntryRef::Vacant(_) => unreachable!(),
4469	/// EntryRef::Occupied(mut view) => {
4470	/// assert_eq!(view.get(), &`100`);
4471	/// let v = view.get_mut();
4472	/// v = `10`;
4473	/// assert_eq!(view.insert(`1111`), `1000`);
4474	/// }
4475	/// }
4476	///
4477	/// assert_eq!(map["a"], `1111`);
4478	/// assert_eq!(map.len(), `3`);
4479	///
4480	/// // Existing key (take)
4481	/// match map.entry_ref("c") {
4482	/// EntryRef::Vacant(_) => unreachable!(),
4483	/// EntryRef::Occupied(view) => {
4484	/// assert_eq!(view.remove_entry(), ("c".to_owned(), `30`));
4485	/// }
4486	/// }
4487	/// assert_eq!(map.get("c"), None);
4488	/// assert_eq!(map.len(), `2`);
4489	/// ```
4490	pub struct OccupiedEntryRef<'a, 'b, K, Q: ?Sized, V, S, A: Allocator = Global> {
4491	hash: u64,
4492	key: Option<KeyOrRef<'b, K, Q>>,
4493	elem: Bucket<(K, V)>,
4494	table: &'a mut HashMap<K, V, S, A>,
4495	}
4496
4497	unsafe impl<'a, 'b, K, Q, V, S, A> Send for OccupiedEntryRef<'a, 'b, K, Q, V, S, A>
4498	where
4499	K: Send,
4500	Q: Sync + ?Sized,
4501	V: Send,
4502	S: Send,
4503	A: Send + Allocator,
4504	{
4505	}
4506	unsafe impl<'a, 'b, K, Q, V, S, A> Sync for OccupiedEntryRef<'a, 'b, K, Q, V, S, A>
4507	where
4508	K: Sync,
4509	Q: Sync + ?Sized,
4510	V: Sync,
4511	S: Sync,
4512	A: Sync + Allocator,
4513	{
4514	}
4515
4516	impl<K: Borrow<Q>, Q: ?Sized + Debug, V: Debug, S, A: Allocator> Debug
4517	for OccupiedEntryRef<'_, '_, K, Q, V, S, A>
4518	{
4519	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4520	f&mut DebugStruct<'_, '_>.debug_struct("OccupiedEntryRef")
4521	.field("key", &self.key().borrow())
4522	.field(name:"value", &self.get())
4523	.finish()
4524	}
4525	}
4526
4527	/// A view into a vacant entry in a `HashMap`.
4528	/// It is part of the [`EntryRef`] enum.
4529	///
4530	/// [`EntryRef`]: enum.EntryRef.html
4531	///
4532	/// # Examples
4533	///
4534	/// ```
4535	/// use hashbrown::hash_map::{EntryRef, HashMap, VacantEntryRef};
4536	///
4537	/// let mut map = HashMap::<String, i32>::new();
4538	///
4539	/// let entry_v: VacantEntryRef<_, _, _, _> = match map.entry_ref("a") {
4540	/// EntryRef::Vacant(view) => view,
4541	/// EntryRef::Occupied(_) => unreachable!(),
4542	/// };
4543	/// entry_v.insert(`10`);
4544	/// assert!(map["a"] == `10` && map.len() == `1`);
4545	///
4546	/// // Nonexistent key (insert and update)
4547	/// match map.entry_ref("b") {
4548	/// EntryRef::Occupied(_) => unreachable!(),
4549	/// EntryRef::Vacant(view) => {
4550	/// let value = view.insert(`2`);
4551	/// assert_eq!(*value, `2`);
4552	/// *value = `20`;
4553	/// }
4554	/// }
4555	/// assert!(map["b"] == `20` && map.len() == `2`);
4556	/// ```
4557	pub struct VacantEntryRef<'a, 'b, K, Q: ?Sized, V, S, A: Allocator = Global> {
4558	hash: u64,
4559	key: KeyOrRef<'b, K, Q>,
4560	table: &'a mut HashMap<K, V, S, A>,
4561	}
4562
4563	impl<K: Borrow<Q>, Q: ?Sized + Debug, V, S, A: Allocator> Debug
4564	for VacantEntryRef<'_, '_, K, Q, V, S, A>
4565	{
4566	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4567	f.debug_tuple(name:"VacantEntryRef").field(&self.key()).finish()
4568	}
4569	}
4570
4571	/// The error returned by [`try_insert`](HashMap::try_insert) when the key already exists.
4572	///
4573	/// Contains the occupied entry, and the value that was not inserted.
4574	///
4575	/// # Examples
4576	///
4577	/// ```
4578	/// use hashbrown::hash_map::{HashMap, OccupiedError};
4579	///
4580	/// let mut map: HashMap<_, _> = [("a", `10`), ("b", `20`)].into();
4581	///
4582	/// // try_insert method returns mutable reference to the value if keys are vacant,
4583	/// // but if the map did have key present, nothing is updated, and the provided
4584	/// // value is returned inside `Err(_)` variant
4585	/// match map.try_insert("a", `100`) {
4586	/// Err(OccupiedError { mut entry, value }) => {
4587	/// assert_eq!(entry.key(), &"a");
4588	/// assert_eq!(value, `100`);
4589	/// assert_eq!(entry.insert(`100`), `10`)
4590	/// }
4591	/// _ => unreachable!(),
4592	/// }
4593	/// assert_eq!(map[&"a"], `100`);
4594	/// ```
4595	pub struct OccupiedError<'a, K, V, S, A: Allocator = Global> {
4596	/// The entry in the map that was already occupied.
4597	pub entry: OccupiedEntry<'a, K, V, S, A>,
4598	/// The value which was not inserted, because the entry was already occupied.
4599	pub value: V,
4600	}
4601
4602	impl<K: Debug, V: Debug, S, A: Allocator> Debug for OccupiedError<'_, K, V, S, A> {
4603	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4604	f&mut DebugStruct<'_, '_>.debug_struct("OccupiedError")
4605	.field("key", self.entry.key())
4606	.field("old_value", self.entry.get())
4607	.field(name:"new_value", &self.value)
4608	.finish()
4609	}
4610	}
4611
4612	impl<'a, K: Debug, V: Debug, S, A: Allocator> fmt::Display for OccupiedError<'a, K, V, S, A> {
4613	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4614	write!(
4615	f,
4616	"failed to insert {:?}, key {:?} already exists with value {:?}",
4617	self.value,
4618	self.entry.key(),
4619	self.entry.get(),
4620	)
4621	}
4622	}
4623
4624	impl<'a, K, V, S, A: Allocator> IntoIterator for &'a HashMap<K, V, S, A> {
4625	type Item = (&'a K, &'a V);
4626	type IntoIter = Iter<'a, K, V>;
4627
4628	/// Creates an iterator over the entries of a `HashMap` in arbitrary order.
4629	/// The iterator element type is `(&'a K, &'a V)`.
4630	///
4631	/// Return the same `Iter` struct as by the [`iter`] method on [`HashMap`].
4632	///
4633	/// [`iter`]: struct.HashMap.html#method.iter
4634	/// [`HashMap`]: struct.HashMap.html
4635	///
4636	/// # Examples
4637	///
4638	/// ```
4639	/// use hashbrown::HashMap;
4640	/// let map_one: HashMap<_, _> = [(`1`, "a"), (`2`, "b"), (`3`, "c")].into();
4641	/// let mut map_two = HashMap::new();
4642	///
4643	/// for (key, value) in &map_one {
4644	/// println!("Key: {}, Value: {}", key, value);
4645	/// map_two.insert_unique_unchecked(key, value);
4646	/// }
4647	///
4648	/// assert_eq!(map_one, map_two);
4649	/// ```
4650	#[cfg_attr(feature = "inline-more", inline)]
4651	fn into_iter(self) -> Iter<'a, K, V> {
4652	self.iter()
4653	}
4654	}
4655
4656	impl<'a, K, V, S, A: Allocator> IntoIterator for &'a mut HashMap<K, V, S, A> {
4657	type Item = (&'a K, &'a mut V);
4658	type IntoIter = IterMut<'a, K, V>;
4659
4660	/// Creates an iterator over the entries of a `HashMap` in arbitrary order
4661	/// with mutable references to the values. The iterator element type is
4662	/// `(&'a K, &'a mut V)`.
4663	///
4664	/// Return the same `IterMut` struct as by the [`iter_mut`] method on
4665	/// [`HashMap`].
4666	///
4667	/// [`iter_mut`]: struct.HashMap.html#method.iter_mut
4668	/// [`HashMap`]: struct.HashMap.html
4669	///
4670	/// # Examples
4671	///
4672	/// ```
4673	/// use hashbrown::HashMap;
4674	/// let mut map: HashMap<_, _> = [("a", `1`), ("b", `2`), ("c", `3`)].into();
4675	///
4676	/// for (key, value) in &mut map {
4677	/// println!("Key: {}, Value: {}", key, value);
4678	/// value = `2`;
4679	/// }
4680	///
4681	/// let mut vec = map.iter().collect::<Vec<_>>();
4682	/// // The `Iter` iterator produces items in arbitrary order, so the
4683	/// // items must be sorted to test them against a sorted array.
4684	/// vec.sort_unstable();
4685	/// assert_eq!(vec, [(&"a", &`2`), (&"b", &`4`), (&"c", &`6`)]);
4686	/// ```
4687	#[cfg_attr(feature = "inline-more", inline)]
4688	fn into_iter(self) -> IterMut<'a, K, V> {
4689	self.iter_mut()
4690	}
4691	}
4692
4693	impl<K, V, S, A: Allocator> IntoIterator for HashMap<K, V, S, A> {
4694	type Item = (K, V);
4695	type IntoIter = IntoIter<K, V, A>;
4696
4697	/// Creates a consuming iterator, that is, one that moves each key-value
4698	/// pair out of the map in arbitrary order. The map cannot be used after
4699	/// calling this.
4700	///
4701	/// # Examples
4702	///
4703	/// ```
4704	/// use hashbrown::HashMap;
4705	///
4706	/// let map: HashMap<_, _> = [("a", `1`), ("b", `2`), ("c", `3`)].into();
4707	///
4708	/// // Not possible with .iter()
4709	/// let mut vec: Vec<(&str, i32)> = map.into_iter().collect();
4710	/// // The `IntoIter` iterator produces items in arbitrary order, so
4711	/// // the items must be sorted to test them against a sorted array.
4712	/// vec.sort_unstable();
4713	/// assert_eq!(vec, [("a", `1`), ("b", `2`), ("c", `3`)]);
4714	/// ```
4715	#[cfg_attr(feature = "inline-more", inline)]
4716	fn into_iter(self) -> IntoIter<K, V, A> {
4717	IntoIter {
4718	inner: self.table.into_iter(),
4719	}
4720	}
4721	}
4722
4723	impl<'a, K, V> Iterator for Iter<'a, K, V> {
4724	type Item = (&'a K, &'a V);
4725
4726	#[cfg_attr(feature = "inline-more", inline)]
4727	fn next(&mut self) -> Option<(&'a K, &'a V)> {
4728	// Avoid `Option::map` because it bloats LLVM IR.
4729	match self.inner.next() {
4730	Some(x) => unsafe {
4731	let r = x.as_ref();
4732	Some((&r.0, &r.1))
4733	},
4734	None => None,
4735	}
4736	}
4737	#[cfg_attr(feature = "inline-more", inline)]
4738	fn size_hint(&self) -> (usize, Option<usize>) {
4739	self.inner.size_hint()
4740	}
4741	#[cfg_attr(feature = "inline-more", inline)]
4742	fn fold<B, F>(self, init: B, mut f: F) -> B
4743	where
4744	Self: Sized,
4745	F: FnMut(B, Self::Item) -> B,
4746	{
4747	self.inner.fold(init, \|acc, x\| unsafe {
4748	let (k, v) = x.as_ref();
4749	f(acc, (k, v))
4750	})
4751	}
4752	}
4753	impl<K, V> ExactSizeIterator for Iter<'_, K, V> {
4754	#[cfg_attr(feature = "inline-more", inline)]
4755	fn len(&self) -> usize {
4756	self.inner.len()
4757	}
4758	}
4759
4760	impl<K, V> FusedIterator for Iter<'_, K, V> {}
4761
4762	impl<'a, K, V> Iterator for IterMut<'a, K, V> {
4763	type Item = (&'a K, &'a mut V);
4764
4765	#[cfg_attr(feature = "inline-more", inline)]
4766	fn next(&mut self) -> Option<(&'a K, &'a mut V)> {
4767	// Avoid `Option::map` because it bloats LLVM IR.
4768	match self.inner.next() {
4769	Some(x) => unsafe {
4770	let r = x.as_mut();
4771	Some((&r.0, &mut r.1))
4772	},
4773	None => None,
4774	}
4775	}
4776	#[cfg_attr(feature = "inline-more", inline)]
4777	fn size_hint(&self) -> (usize, Option<usize>) {
4778	self.inner.size_hint()
4779	}
4780	#[cfg_attr(feature = "inline-more", inline)]
4781	fn fold<B, F>(self, init: B, mut f: F) -> B
4782	where
4783	Self: Sized,
4784	F: FnMut(B, Self::Item) -> B,
4785	{
4786	self.inner.fold(init, \|acc, x\| unsafe {
4787	let (k, v) = x.as_mut();
4788	f(acc, (k, v))
4789	})
4790	}
4791	}
4792	impl<K, V> ExactSizeIterator for IterMut<'_, K, V> {
4793	#[cfg_attr(feature = "inline-more", inline)]
4794	fn len(&self) -> usize {
4795	self.inner.len()
4796	}
4797	}
4798	impl<K, V> FusedIterator for IterMut<'_, K, V> {}
4799
4800	impl<K, V> fmt::Debug for IterMut<'_, K, V>
4801	where
4802	K: fmt::Debug,
4803	V: fmt::Debug,
4804	{
4805	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4806	f.debug_list().entries(self.iter()).finish()
4807	}
4808	}
4809
4810	impl<K, V, A: Allocator> Iterator for IntoIter<K, V, A> {
4811	type Item = (K, V);
4812
4813	#[cfg_attr(feature = "inline-more", inline)]
4814	fn next(&mut self) -> Option<(K, V)> {
4815	self.inner.next()
4816	}
4817	#[cfg_attr(feature = "inline-more", inline)]
4818	fn size_hint(&self) -> (usize, Option<usize>) {
4819	self.inner.size_hint()
4820	}
4821	#[cfg_attr(feature = "inline-more", inline)]
4822	fn fold<B, F>(self, init: B, f: F) -> B
4823	where
4824	Self: Sized,
4825	F: FnMut(B, Self::Item) -> B,
4826	{
4827	self.inner.fold(init, f)
4828	}
4829	}
4830	impl<K, V, A: Allocator> ExactSizeIterator for IntoIter<K, V, A> {
4831	#[cfg_attr(feature = "inline-more", inline)]
4832	fn len(&self) -> usize {
4833	self.inner.len()
4834	}
4835	}
4836	impl<K, V, A: Allocator> FusedIterator for IntoIter<K, V, A> {}
4837
4838	impl<K: Debug, V: Debug, A: Allocator> fmt::Debug for IntoIter<K, V, A> {
4839	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4840	f.debug_list().entries(self.iter()).finish()
4841	}
4842	}
4843
4844	impl<'a, K, V> Iterator for Keys<'a, K, V> {
4845	type Item = &'a K;
4846
4847	#[cfg_attr(feature = "inline-more", inline)]
4848	fn next(&mut self) -> Option<&'a K> {
4849	// Avoid `Option::map` because it bloats LLVM IR.
4850	match self.inner.next() {
4851	Some((k: &'a K, _)) => Some(k),
4852	None => None,
4853	}
4854	}
4855	#[cfg_attr(feature = "inline-more", inline)]
4856	fn size_hint(&self) -> (usize, Option<usize>) {
4857	self.inner.size_hint()
4858	}
4859	#[cfg_attr(feature = "inline-more", inline)]
4860	fn fold<B, F>(self, init: B, mut f: F) -> B
4861	where
4862	Self: Sized,
4863	F: FnMut(B, Self::Item) -> B,
4864	{
4865	self.inner.fold(init, \|acc: B, (k: &'a K, _)\| f(acc, k))
4866	}
4867	}
4868	impl<K, V> ExactSizeIterator for Keys<'_, K, V> {
4869	#[cfg_attr(feature = "inline-more", inline)]
4870	fn len(&self) -> usize {
4871	self.inner.len()
4872	}
4873	}
4874	impl<K, V> FusedIterator for Keys<'_, K, V> {}
4875
4876	impl<'a, K, V> Iterator for Values<'a, K, V> {
4877	type Item = &'a V;
4878
4879	#[cfg_attr(feature = "inline-more", inline)]
4880	fn next(&mut self) -> Option<&'a V> {
4881	// Avoid `Option::map` because it bloats LLVM IR.
4882	match self.inner.next() {
4883	Some((_, v: &'a V)) => Some(v),
4884	None => None,
4885	}
4886	}
4887	#[cfg_attr(feature = "inline-more", inline)]
4888	fn size_hint(&self) -> (usize, Option<usize>) {
4889	self.inner.size_hint()
4890	}
4891	#[cfg_attr(feature = "inline-more", inline)]
4892	fn fold<B, F>(self, init: B, mut f: F) -> B
4893	where
4894	Self: Sized,
4895	F: FnMut(B, Self::Item) -> B,
4896	{
4897	self.inner.fold(init, \|acc: B, (_, v: &'a V)\| f(acc, v))
4898	}
4899	}
4900	impl<K, V> ExactSizeIterator for Values<'_, K, V> {
4901	#[cfg_attr(feature = "inline-more", inline)]
4902	fn len(&self) -> usize {
4903	self.inner.len()
4904	}
4905	}
4906	impl<K, V> FusedIterator for Values<'_, K, V> {}
4907
4908	impl<'a, K, V> Iterator for ValuesMut<'a, K, V> {
4909	type Item = &'a mut V;
4910
4911	#[cfg_attr(feature = "inline-more", inline)]
4912	fn next(&mut self) -> Option<&'a mut V> {
4913	// Avoid `Option::map` because it bloats LLVM IR.
4914	match self.inner.next() {
4915	Some((_, v: &'a mut V)) => Some(v),
4916	None => None,
4917	}
4918	}
4919	#[cfg_attr(feature = "inline-more", inline)]
4920	fn size_hint(&self) -> (usize, Option<usize>) {
4921	self.inner.size_hint()
4922	}
4923	#[cfg_attr(feature = "inline-more", inline)]
4924	fn fold<B, F>(self, init: B, mut f: F) -> B
4925	where
4926	Self: Sized,
4927	F: FnMut(B, Self::Item) -> B,
4928	{
4929	self.inner.fold(init, \|acc: B, (_, v: &'a mut V)\| f(acc, v))
4930	}
4931	}
4932	impl<K, V> ExactSizeIterator for ValuesMut<'_, K, V> {
4933	#[cfg_attr(feature = "inline-more", inline)]
4934	fn len(&self) -> usize {
4935	self.inner.len()
4936	}
4937	}
4938	impl<K, V> FusedIterator for ValuesMut<'_, K, V> {}
4939
4940	impl<K, V: Debug> fmt::Debug for ValuesMut<'_, K, V> {
4941	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4942	f&mut DebugList<'_, '_>.debug_list()
4943	.entries(self.inner.iter().map(\|(_, val: &V)\| val))
4944	.finish()
4945	}
4946	}
4947
4948	impl<'a, K, V, A: Allocator> Iterator for Drain<'a, K, V, A> {
4949	type Item = (K, V);
4950
4951	#[cfg_attr(feature = "inline-more", inline)]
4952	fn next(&mut self) -> Option<(K, V)> {
4953	self.inner.next()
4954	}
4955	#[cfg_attr(feature = "inline-more", inline)]
4956	fn size_hint(&self) -> (usize, Option<usize>) {
4957	self.inner.size_hint()
4958	}
4959	#[cfg_attr(feature = "inline-more", inline)]
4960	fn fold<B, F>(self, init: B, f: F) -> B
4961	where
4962	Self: Sized,
4963	F: FnMut(B, Self::Item) -> B,
4964	{
4965	self.inner.fold(init, f)
4966	}
4967	}
4968	impl<K, V, A: Allocator> ExactSizeIterator for Drain<'_, K, V, A> {
4969	#[cfg_attr(feature = "inline-more", inline)]
4970	fn len(&self) -> usize {
4971	self.inner.len()
4972	}
4973	}
4974	impl<K, V, A: Allocator> FusedIterator for Drain<'_, K, V, A> {}
4975
4976	impl<K, V, A> fmt::Debug for Drain<'_, K, V, A>
4977	where
4978	K: fmt::Debug,
4979	V: fmt::Debug,
4980	A: Allocator,
4981	{
4982	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4983	f.debug_list().entries(self.iter()).finish()
4984	}
4985	}
4986
4987	impl<'a, K, V, S, A: Allocator> Entry<'a, K, V, S, A> {
4988	/// Sets the value of the entry, and returns an OccupiedEntry.
4989	///
4990	/// # Examples
4991	///
4992	/// ```
4993	/// use hashbrown::HashMap;
4994	///
4995	/// let mut map: HashMap<&str, u32> = HashMap::new();
4996	/// let entry = map.entry("horseyland").insert(`37`);
4997	///
4998	/// assert_eq!(entry.key(), &"horseyland");
4999	/// ```
5000	#[cfg_attr(feature = "inline-more", inline)]
5001	pub fn insert(self, value: V) -> OccupiedEntry<'a, K, V, S, A>
5002	where
5003	K: Hash,
5004	S: BuildHasher,
5005	{
5006	match self {
5007	Entry::Occupied(mut entry) => {
5008	entry.insert(value);
5009	entry
5010	}
5011	Entry::Vacant(entry) => entry.insert_entry(value),
5012	}
5013	}
5014
5015	/// Ensures a value is in the entry by inserting the default if empty, and returns
5016	/// a mutable reference to the value in the entry.
5017	///
5018	/// # Examples
5019	///
5020	/// ```
5021	/// use hashbrown::HashMap;
5022	///
5023	/// let mut map: HashMap<&str, u32> = HashMap::new();
5024	///
5025	/// // nonexistent key
5026	/// map.entry("poneyland").or_insert(`3`);
5027	/// assert_eq!(map["poneyland"], `3`);
5028	///
5029	/// // existing key
5030	/// map.entry("poneyland").or_insert(`10`) = `2`;
5031	/// assert_eq!(map["poneyland"], `6`);
5032	/// ```
5033	#[cfg_attr(feature = "inline-more", inline)]
5034	pub fn or_insert(self, default: V) -> &'a mut V
5035	where
5036	K: Hash,
5037	S: BuildHasher,
5038	{
5039	match self {
5040	Entry::Occupied(entry) => entry.into_mut(),
5041	Entry::Vacant(entry) => entry.insert(default),
5042	}
5043	}
5044
5045	/// Ensures a value is in the entry by inserting the result of the default function if empty,
5046	/// and returns a mutable reference to the value in the entry.
5047	///
5048	/// # Examples
5049	///
5050	/// ```
5051	/// use hashbrown::HashMap;
5052	///
5053	/// let mut map: HashMap<&str, u32> = HashMap::new();
5054	///
5055	/// // nonexistent key
5056	/// map.entry("poneyland").or_insert_with(\|\| `3`);
5057	/// assert_eq!(map["poneyland"], `3`);
5058	///
5059	/// // existing key
5060	/// map.entry("poneyland").or_insert_with(\|\| `10`) = `2`;
5061	/// assert_eq!(map["poneyland"], `6`);
5062	/// ```
5063	#[cfg_attr(feature = "inline-more", inline)]
5064	pub fn or_insert_with<F: FnOnce() -> V>(self, default: F) -> &'a mut V
5065	where
5066	K: Hash,
5067	S: BuildHasher,
5068	{
5069	match self {
5070	Entry::Occupied(entry) => entry.into_mut(),
5071	Entry::Vacant(entry) => entry.insert(default()),
5072	}
5073	}
5074
5075	/// Ensures a value is in the entry by inserting, if empty, the result of the default function.
5076	/// This method allows for generating key-derived values for insertion by providing the default
5077	/// function a reference to the key that was moved during the `.entry(key)` method call.
5078	///
5079	/// The reference to the moved key is provided so that cloning or copying the key is
5080	/// unnecessary, unlike with `.or_insert_with(\|\| ... )`.
5081	///
5082	/// # Examples
5083	///
5084	/// ```
5085	/// use hashbrown::HashMap;
5086	///
5087	/// let mut map: HashMap<&str, usize> = HashMap::new();
5088	///
5089	/// // nonexistent key
5090	/// map.entry("poneyland").or_insert_with_key(\|key\| key.chars().count());
5091	/// assert_eq!(map["poneyland"], `9`);
5092	///
5093	/// // existing key
5094	/// map.entry("poneyland").or_insert_with_key(\|key\| key.chars().count() `10`) *= `2`;
5095	/// assert_eq!(map["poneyland"], `18`);
5096	/// ```
5097	#[cfg_attr(feature = "inline-more", inline)]
5098	pub fn or_insert_with_key<F: FnOnce(&K) -> V>(self, default: F) -> &'a mut V
5099	where
5100	K: Hash,
5101	S: BuildHasher,
5102	{
5103	match self {
5104	Entry::Occupied(entry) => entry.into_mut(),
5105	Entry::Vacant(entry) => {
5106	let value = default(entry.key());
5107	entry.insert(value)
5108	}
5109	}
5110	}
5111
5112	/// Returns a reference to this entry's key.
5113	///
5114	/// # Examples
5115	///
5116	/// ```
5117	/// use hashbrown::HashMap;
5118	///
5119	/// let mut map: HashMap<&str, u32> = HashMap::new();
5120	/// map.entry("poneyland").or_insert(`3`);
5121	/// // existing key
5122	/// assert_eq!(map.entry("poneyland").key(), &"poneyland");
5123	/// // nonexistent key
5124	/// assert_eq!(map.entry("horseland").key(), &"horseland");
5125	/// ```
5126	#[cfg_attr(feature = "inline-more", inline)]
5127	pub fn key(&self) -> &K {
5128	match *self {
5129	Entry::Occupied(ref entry) => entry.key(),
5130	Entry::Vacant(ref entry) => entry.key(),
5131	}
5132	}
5133
5134	/// Provides in-place mutable access to an occupied entry before any
5135	/// potential inserts into the map.
5136	///
5137	/// # Examples
5138	///
5139	/// ```
5140	/// use hashbrown::HashMap;
5141	///
5142	/// let mut map: HashMap<&str, u32> = HashMap::new();
5143	///
5144	/// map.entry("poneyland")
5145	/// .and_modify(\|e\| { *e += `1` })
5146	/// .or_insert(`42`);
5147	/// assert_eq!(map["poneyland"], `42`);
5148	///
5149	/// map.entry("poneyland")
5150	/// .and_modify(\|e\| { *e += `1` })
5151	/// .or_insert(`42`);
5152	/// assert_eq!(map["poneyland"], `43`);
5153	/// ```
5154	#[cfg_attr(feature = "inline-more", inline)]
5155	pub fn and_modify<F>(self, f: F) -> Self
5156	where
5157	F: FnOnce(&mut V),
5158	{
5159	match self {
5160	Entry::Occupied(mut entry) => {
5161	f(entry.get_mut());
5162	Entry::Occupied(entry)
5163	}
5164	Entry::Vacant(entry) => Entry::Vacant(entry),
5165	}
5166	}
5167
5168	/// Provides shared access to the key and owned access to the value of
5169	/// an occupied entry and allows to replace or remove it based on the
5170	/// value of the returned option.
5171	///
5172	/// # Examples
5173	///
5174	/// ```
5175	/// use hashbrown::HashMap;
5176	/// use hashbrown::hash_map::Entry;
5177	///
5178	/// let mut map: HashMap<&str, u32> = HashMap::new();
5179	///
5180	/// let entry = map
5181	/// .entry("poneyland")
5182	/// .and_replace_entry_with(\|_k, _v\| panic!());
5183	///
5184	/// match entry {
5185	/// Entry::Vacant(e) => {
5186	/// assert_eq!(e.key(), &"poneyland");
5187	/// }
5188	/// Entry::Occupied(_) => panic!(),
5189	/// }
5190	///
5191	/// map.insert("poneyland", `42`);
5192	///
5193	/// let entry = map
5194	/// .entry("poneyland")
5195	/// .and_replace_entry_with(\|k, v\| {
5196	/// assert_eq!(k, &"poneyland");
5197	/// assert_eq!(v, `42`);
5198	/// Some(v + `1`)
5199	/// });
5200	///
5201	/// match entry {
5202	/// Entry::Occupied(e) => {
5203	/// assert_eq!(e.key(), &"poneyland");
5204	/// assert_eq!(e.get(), &`43`);
5205	/// }
5206	/// Entry::Vacant(_) => panic!(),
5207	/// }
5208	///
5209	/// assert_eq!(map["poneyland"], `43`);
5210	///
5211	/// let entry = map
5212	/// .entry("poneyland")
5213	/// .and_replace_entry_with(\|_k, _v\| None);
5214	///
5215	/// match entry {
5216	/// Entry::Vacant(e) => assert_eq!(e.key(), &"poneyland"),
5217	/// Entry::Occupied(_) => panic!(),
5218	/// }
5219	///
5220	/// assert!(!map.contains_key("poneyland"));
5221	/// ```
5222	#[cfg_attr(feature = "inline-more", inline)]
5223	pub fn and_replace_entry_with<F>(self, f: F) -> Self
5224	where
5225	F: FnOnce(&K, V) -> Option<V>,
5226	{
5227	match self {
5228	Entry::Occupied(entry) => entry.replace_entry_with(f),
5229	Entry::Vacant(_) => self,
5230	}
5231	}
5232	}
5233
5234	impl<'a, K, V: Default, S, A: Allocator> Entry<'a, K, V, S, A> {
5235	/// Ensures a value is in the entry by inserting the default value if empty,
5236	/// and returns a mutable reference to the value in the entry.
5237	///
5238	/// # Examples
5239	///
5240	/// ```
5241	/// use hashbrown::HashMap;
5242	///
5243	/// let mut map: HashMap<&str, Option<u32>> = HashMap::new();
5244	///
5245	/// // nonexistent key
5246	/// map.entry("poneyland").or_default();
5247	/// assert_eq!(map["poneyland"], None);
5248	///
5249	/// map.insert("horseland", Some(`3`));
5250	///
5251	/// // existing key
5252	/// assert_eq!(map.entry("horseland").or_default(), &mut Some(`3`));
5253	/// ```
5254	#[cfg_attr(feature = "inline-more", inline)]
5255	pub fn or_default(self) -> &'a mut V
5256	where
5257	K: Hash,
5258	S: BuildHasher,
5259	{
5260	match self {
5261	Entry::Occupied(entry) => entry.into_mut(),
5262	Entry::Vacant(entry) => entry.insert(Default::default()),
5263	}
5264	}
5265	}
5266
5267	impl<'a, K, V, S, A: Allocator> OccupiedEntry<'a, K, V, S, A> {
5268	/// Gets a reference to the key in the entry.
5269	///
5270	/// # Examples
5271	///
5272	/// ```
5273	/// use hashbrown::hash_map::{Entry, HashMap};
5274	///
5275	/// let mut map: HashMap<&str, u32> = HashMap::new();
5276	/// map.entry("poneyland").or_insert(`12`);
5277	///
5278	/// match map.entry("poneyland") {
5279	/// Entry::Vacant(_) => panic!(),
5280	/// Entry::Occupied(entry) => assert_eq!(entry.key(), &"poneyland"),
5281	/// }
5282	/// ```
5283	#[cfg_attr(feature = "inline-more", inline)]
5284	pub fn key(&self) -> &K {
5285	unsafe { &self.elem.as_ref().0 }
5286	}
5287
5288	/// Take the ownership of the key and value from the map.
5289	/// Keeps the allocated memory for reuse.
5290	///
5291	/// # Examples
5292	///
5293	/// ```
5294	/// use hashbrown::HashMap;
5295	/// use hashbrown::hash_map::Entry;
5296	///
5297	/// let mut map: HashMap<&str, u32> = HashMap::new();
5298	/// // The map is empty
5299	/// assert!(map.is_empty() && map.capacity() == `0`);
5300	///
5301	/// map.entry("poneyland").or_insert(`12`);
5302	///
5303	/// if let Entry::Occupied(o) = map.entry("poneyland") {
5304	/// // We delete the entry from the map.
5305	/// assert_eq!(o.remove_entry(), ("poneyland", `12`));
5306	/// }
5307	///
5308	/// assert_eq!(map.contains_key("poneyland"), `false`);
5309	/// // Now map hold none elements
5310	/// assert!(map.is_empty());
5311	/// ```
5312	#[cfg_attr(feature = "inline-more", inline)]
5313	pub fn remove_entry(self) -> (K, V) {
5314	unsafe { self.table.table.remove(self.elem).0 }
5315	}
5316
5317	/// Gets a reference to the value in the entry.
5318	///
5319	/// # Examples
5320	///
5321	/// ```
5322	/// use hashbrown::HashMap;
5323	/// use hashbrown::hash_map::Entry;
5324	///
5325	/// let mut map: HashMap<&str, u32> = HashMap::new();
5326	/// map.entry("poneyland").or_insert(`12`);
5327	///
5328	/// match map.entry("poneyland") {
5329	/// Entry::Vacant(_) => panic!(),
5330	/// Entry::Occupied(entry) => assert_eq!(entry.get(), &`12`),
5331	/// }
5332	/// ```
5333	#[cfg_attr(feature = "inline-more", inline)]
5334	pub fn get(&self) -> &V {
5335	unsafe { &self.elem.as_ref().1 }
5336	}
5337
5338	/// Gets a mutable reference to the value in the entry.
5339	///
5340	/// If you need a reference to the `OccupiedEntry` which may outlive the
5341	/// destruction of the `Entry` value, see [`into_mut`].
5342	///
5343	/// [`into_mut`]: #method.into_mut
5344	///
5345	/// # Examples
5346	///
5347	/// ```
5348	/// use hashbrown::HashMap;
5349	/// use hashbrown::hash_map::Entry;
5350	///
5351	/// let mut map: HashMap<&str, u32> = HashMap::new();
5352	/// map.entry("poneyland").or_insert(`12`);
5353	///
5354	/// assert_eq!(map["poneyland"], `12`);
5355	/// if let Entry::Occupied(mut o) = map.entry("poneyland") {
5356	/// *o.get_mut() += `10`;
5357	/// assert_eq!(*o.get(), `22`);
5358	///
5359	/// // We can use the same Entry multiple times.
5360	/// *o.get_mut() += `2`;
5361	/// }
5362	///
5363	/// assert_eq!(map["poneyland"], `24`);
5364	/// ```
5365	#[cfg_attr(feature = "inline-more", inline)]
5366	pub fn get_mut(&mut self) -> &mut V {
5367	unsafe { &mut self.elem.as_mut().1 }
5368	}
5369
5370	/// Converts the OccupiedEntry into a mutable reference to the value in the entry
5371	/// with a lifetime bound to the map itself.
5372	///
5373	/// If you need multiple references to the `OccupiedEntry`, see [`get_mut`].
5374	///
5375	/// [`get_mut`]: #method.get_mut
5376	///
5377	/// # Examples
5378	///
5379	/// ```
5380	/// use hashbrown::hash_map::{Entry, HashMap};
5381	///
5382	/// let mut map: HashMap<&str, u32> = HashMap::new();
5383	/// map.entry("poneyland").or_insert(`12`);
5384	///
5385	/// assert_eq!(map["poneyland"], `12`);
5386	///
5387	/// let value: &mut u32;
5388	/// match map.entry("poneyland") {
5389	/// Entry::Occupied(entry) => value = entry.into_mut(),
5390	/// Entry::Vacant(_) => panic!(),
5391	/// }
5392	/// *value += `10`;
5393	///
5394	/// assert_eq!(map["poneyland"], `22`);
5395	/// ```
5396	#[cfg_attr(feature = "inline-more", inline)]
5397	pub fn into_mut(self) -> &'a mut V {
5398	unsafe { &mut self.elem.as_mut().1 }
5399	}
5400
5401	/// Sets the value of the entry, and returns the entry's old value.
5402	///
5403	/// # Examples
5404	///
5405	/// ```
5406	/// use hashbrown::HashMap;
5407	/// use hashbrown::hash_map::Entry;
5408	///
5409	/// let mut map: HashMap<&str, u32> = HashMap::new();
5410	/// map.entry("poneyland").or_insert(`12`);
5411	///
5412	/// if let Entry::Occupied(mut o) = map.entry("poneyland") {
5413	/// assert_eq!(o.insert(`15`), `12`);
5414	/// }
5415	///
5416	/// assert_eq!(map["poneyland"], `15`);
5417	/// ```
5418	#[cfg_attr(feature = "inline-more", inline)]
5419	pub fn insert(&mut self, value: V) -> V {
5420	mem::replace(self.get_mut(), value)
5421	}
5422
5423	/// Takes the value out of the entry, and returns it.
5424	/// Keeps the allocated memory for reuse.
5425	///
5426	/// # Examples
5427	///
5428	/// ```
5429	/// use hashbrown::HashMap;
5430	/// use hashbrown::hash_map::Entry;
5431	///
5432	/// let mut map: HashMap<&str, u32> = HashMap::new();
5433	/// // The map is empty
5434	/// assert!(map.is_empty() && map.capacity() == `0`);
5435	///
5436	/// map.entry("poneyland").or_insert(`12`);
5437	///
5438	/// if let Entry::Occupied(o) = map.entry("poneyland") {
5439	/// assert_eq!(o.remove(), `12`);
5440	/// }
5441	///
5442	/// assert_eq!(map.contains_key("poneyland"), `false`);
5443	/// // Now map hold none elements
5444	/// assert!(map.is_empty());
5445	/// ```
5446	#[cfg_attr(feature = "inline-more", inline)]
5447	pub fn remove(self) -> V {
5448	self.remove_entry().1
5449	}
5450
5451	/// Replaces the entry, returning the old key and value. The new key in the hash map will be
5452	/// the key used to create this entry.
5453	///
5454	/// # Panics
5455	///
5456	/// Will panic if this OccupiedEntry was created through [`Entry::insert`].
5457	///
5458	/// # Examples
5459	///
5460	/// ```
5461	/// use hashbrown::hash_map::{Entry, HashMap};
5462	/// use std::rc::Rc;
5463	///
5464	/// let mut map: HashMap<Rc<String>, u32> = HashMap::new();
5465	/// let key_one = Rc::new("Stringthing".to_string());
5466	/// let key_two = Rc::new("Stringthing".to_string());
5467	///
5468	/// map.insert(key_one.clone(), `15`);
5469	/// assert!(Rc::strong_count(&key_one) == `2` && Rc::strong_count(&key_two) == `1`);
5470	///
5471	/// match map.entry(key_two.clone()) {
5472	/// Entry::Occupied(entry) => {
5473	/// let (old_key, old_value): (Rc<String>, u32) = entry.replace_entry(`16`);
5474	/// assert!(Rc::ptr_eq(&key_one, &old_key) && old_value == `15`);
5475	/// }
5476	/// Entry::Vacant(_) => panic!(),
5477	/// }
5478	///
5479	/// assert!(Rc::strong_count(&key_one) == `1` && Rc::strong_count(&key_two) == `2`);
5480	/// assert_eq!(map[&"Stringthing".to_owned()], `16`);
5481	/// ```
5482	#[cfg_attr(feature = "inline-more", inline)]
5483	pub fn replace_entry(self, value: V) -> (K, V) {
5484	let entry = unsafe { self.elem.as_mut() };
5485
5486	let old_key = mem::replace(&mut entry.0, self.key.unwrap());
5487	let old_value = mem::replace(&mut entry.1, value);
5488
5489	(old_key, old_value)
5490	}
5491
5492	/// Replaces the key in the hash map with the key used to create this entry.
5493	///
5494	/// # Panics
5495	///
5496	/// Will panic if this OccupiedEntry was created through [`Entry::insert`].
5497	///
5498	/// # Examples
5499	///
5500	/// ```
5501	/// use hashbrown::hash_map::{Entry, HashMap};
5502	/// use std::rc::Rc;
5503	///
5504	/// let mut map: HashMap<Rc<String>, usize> = HashMap::with_capacity(`6`);
5505	/// let mut keys_one: Vec<Rc<String>> = Vec::with_capacity(`6`);
5506	/// let mut keys_two: Vec<Rc<String>> = Vec::with_capacity(`6`);
5507	///
5508	/// for (value, key) in ["a", "b", "c", "d", "e", "f"].into_iter().enumerate() {
5509	/// let rc_key = Rc::new(key.to_owned());
5510	/// keys_one.push(rc_key.clone());
5511	/// map.insert(rc_key.clone(), value);
5512	/// keys_two.push(Rc::new(key.to_owned()));
5513	/// }
5514	///
5515	/// assert!(
5516	/// keys_one.iter().all(\|key\| Rc::strong_count(key) == `2`)
5517	/// && keys_two.iter().all(\|key\| Rc::strong_count(key) == `1`)
5518	/// );
5519	///
5520	/// reclaim_memory(&mut map, &keys_two);
5521	///
5522	/// assert!(
5523	/// keys_one.iter().all(\|key\| Rc::strong_count(key) == `1`)
5524	/// && keys_two.iter().all(\|key\| Rc::strong_count(key) == `2`)
5525	/// );
5526	///
5527	/// fn reclaim_memory(map: &mut HashMap<Rc<String>, usize>, keys: &[Rc<String>]) {
5528	/// for key in keys {
5529	/// if let Entry::Occupied(entry) = map.entry(key.clone()) {
5530	/// // Replaces the entry's key with our version of it in `keys`.
5531	/// entry.replace_key();
5532	/// }
5533	/// }
5534	/// }
5535	/// ```
5536	#[cfg_attr(feature = "inline-more", inline)]
5537	pub fn replace_key(self) -> K {
5538	let entry = unsafe { self.elem.as_mut() };
5539	mem::replace(&mut entry.0, self.key.unwrap())
5540	}
5541
5542	/// Provides shared access to the key and owned access to the value of
5543	/// the entry and allows to replace or remove it based on the
5544	/// value of the returned option.
5545	///
5546	/// # Examples
5547	///
5548	/// ```
5549	/// use hashbrown::HashMap;
5550	/// use hashbrown::hash_map::Entry;
5551	///
5552	/// let mut map: HashMap<&str, u32> = HashMap::new();
5553	/// map.insert("poneyland", `42`);
5554	///
5555	/// let entry = match map.entry("poneyland") {
5556	/// Entry::Occupied(e) => {
5557	/// e.replace_entry_with(\|k, v\| {
5558	/// assert_eq!(k, &"poneyland");
5559	/// assert_eq!(v, `42`);
5560	/// Some(v + `1`)
5561	/// })
5562	/// }
5563	/// Entry::Vacant(_) => panic!(),
5564	/// };
5565	///
5566	/// match entry {
5567	/// Entry::Occupied(e) => {
5568	/// assert_eq!(e.key(), &"poneyland");
5569	/// assert_eq!(e.get(), &`43`);
5570	/// }
5571	/// Entry::Vacant(_) => panic!(),
5572	/// }
5573	///
5574	/// assert_eq!(map["poneyland"], `43`);
5575	///
5576	/// let entry = match map.entry("poneyland") {
5577	/// Entry::Occupied(e) => e.replace_entry_with(\|_k, _v\| None),
5578	/// Entry::Vacant(_) => panic!(),
5579	/// };
5580	///
5581	/// match entry {
5582	/// Entry::Vacant(e) => {
5583	/// assert_eq!(e.key(), &"poneyland");
5584	/// }
5585	/// Entry::Occupied(_) => panic!(),
5586	/// }
5587	///
5588	/// assert!(!map.contains_key("poneyland"));
5589	/// ```
5590	#[cfg_attr(feature = "inline-more", inline)]
5591	pub fn replace_entry_with<F>(self, f: F) -> Entry<'a, K, V, S, A>
5592	where
5593	F: FnOnce(&K, V) -> Option<V>,
5594	{
5595	unsafe {
5596	let mut spare_key = None;
5597
5598	self.table
5599	.table
5600	.replace_bucket_with(self.elem.clone(), \|(key, value)\| {
5601	if let Some(new_value) = f(&key, value) {
5602	Some((key, new_value))
5603	} else {
5604	spare_key = Some(key);
5605	None
5606	}
5607	});
5608
5609	if let Some(key) = spare_key {
5610	Entry::Vacant(VacantEntry {
5611	hash: self.hash,
5612	key,
5613	table: self.table,
5614	})
5615	} else {
5616	Entry::Occupied(self)
5617	}
5618	}
5619	}
5620	}
5621
5622	impl<'a, K, V, S, A: Allocator> VacantEntry<'a, K, V, S, A> {
5623	/// Gets a reference to the key that would be used when inserting a value
5624	/// through the `VacantEntry`.
5625	///
5626	/// # Examples
5627	///
5628	/// ```
5629	/// use hashbrown::HashMap;
5630	///
5631	/// let mut map: HashMap<&str, u32> = HashMap::new();
5632	/// assert_eq!(map.entry("poneyland").key(), &"poneyland");
5633	/// ```
5634	#[cfg_attr(feature = "inline-more", inline)]
5635	pub fn key(&self) -> &K {
5636	&self.key
5637	}
5638
5639	/// Take ownership of the key.
5640	///
5641	/// # Examples
5642	///
5643	/// ```
5644	/// use hashbrown::hash_map::{Entry, HashMap};
5645	///
5646	/// let mut map: HashMap<&str, u32> = HashMap::new();
5647	///
5648	/// match map.entry("poneyland") {
5649	/// Entry::Occupied(_) => panic!(),
5650	/// Entry::Vacant(v) => assert_eq!(v.into_key(), "poneyland"),
5651	/// }
5652	/// ```
5653	#[cfg_attr(feature = "inline-more", inline)]
5654	pub fn into_key(self) -> K {
5655	self.key
5656	}
5657
5658	/// Sets the value of the entry with the VacantEntry's key,
5659	/// and returns a mutable reference to it.
5660	///
5661	/// # Examples
5662	///
5663	/// ```
5664	/// use hashbrown::HashMap;
5665	/// use hashbrown::hash_map::Entry;
5666	///
5667	/// let mut map: HashMap<&str, u32> = HashMap::new();
5668	///
5669	/// if let Entry::Vacant(o) = map.entry("poneyland") {
5670	/// o.insert(`37`);
5671	/// }
5672	/// assert_eq!(map["poneyland"], `37`);
5673	/// ```
5674	#[cfg_attr(feature = "inline-more", inline)]
5675	pub fn insert(self, value: V) -> &'a mut V
5676	where
5677	K: Hash,
5678	S: BuildHasher,
5679	{
5680	let table = &mut self.table.table;
5681	let entry = table.insert_entry(
5682	self.hash,
5683	(self.key, value),
5684	make_hasher::<_, V, S>(&self.table.hash_builder),
5685	);
5686	&mut entry.1
5687	}
5688
5689	#[cfg_attr(feature = "inline-more", inline)]
5690	pub(crate) fn insert_entry(self, value: V) -> OccupiedEntry<'a, K, V, S, A>
5691	where
5692	K: Hash,
5693	S: BuildHasher,
5694	{
5695	let elem = self.table.table.insert(
5696	self.hash,
5697	(self.key, value),
5698	make_hasher::<_, V, S>(&self.table.hash_builder),
5699	);
5700	OccupiedEntry {
5701	hash: self.hash,
5702	key: None,
5703	elem,
5704	table: self.table,
5705	}
5706	}
5707	}
5708
5709	impl<'a, 'b, K, Q: ?Sized, V, S, A: Allocator> EntryRef<'a, 'b, K, Q, V, S, A> {
5710	/// Sets the value of the entry, and returns an OccupiedEntryRef.
5711	///
5712	/// # Examples
5713	///
5714	/// ```
5715	/// use hashbrown::HashMap;
5716	///
5717	/// let mut map: HashMap<String, u32> = HashMap::new();
5718	/// let entry = map.entry_ref("horseyland").insert(`37`);
5719	///
5720	/// assert_eq!(entry.key(), "horseyland");
5721	/// ```
5722	#[cfg_attr(feature = "inline-more", inline)]
5723	pub fn insert(self, value: V) -> OccupiedEntryRef<'a, 'b, K, Q, V, S, A>
5724	where
5725	K: Hash + From<&'b Q>,
5726	S: BuildHasher,
5727	{
5728	match self {
5729	EntryRef::Occupied(mut entry) => {
5730	entry.insert(value);
5731	entry
5732	}
5733	EntryRef::Vacant(entry) => entry.insert_entry(value),
5734	}
5735	}
5736
5737	/// Ensures a value is in the entry by inserting the default if empty, and returns
5738	/// a mutable reference to the value in the entry.
5739	///
5740	/// # Examples
5741	///
5742	/// ```
5743	/// use hashbrown::HashMap;
5744	///
5745	/// let mut map: HashMap<String, u32> = HashMap::new();
5746	///
5747	/// // nonexistent key
5748	/// map.entry_ref("poneyland").or_insert(`3`);
5749	/// assert_eq!(map["poneyland"], `3`);
5750	///
5751	/// // existing key
5752	/// map.entry_ref("poneyland").or_insert(`10`) = `2`;
5753	/// assert_eq!(map["poneyland"], `6`);
5754	/// ```
5755	#[cfg_attr(feature = "inline-more", inline)]
5756	pub fn or_insert(self, default: V) -> &'a mut V
5757	where
5758	K: Hash + From<&'b Q>,
5759	S: BuildHasher,
5760	{
5761	match self {
5762	EntryRef::Occupied(entry) => entry.into_mut(),
5763	EntryRef::Vacant(entry) => entry.insert(default),
5764	}
5765	}
5766
5767	/// Ensures a value is in the entry by inserting the result of the default function if empty,
5768	/// and returns a mutable reference to the value in the entry.
5769	///
5770	/// # Examples
5771	///
5772	/// ```
5773	/// use hashbrown::HashMap;
5774	///
5775	/// let mut map: HashMap<String, u32> = HashMap::new();
5776	///
5777	/// // nonexistent key
5778	/// map.entry_ref("poneyland").or_insert_with(\|\| `3`);
5779	/// assert_eq!(map["poneyland"], `3`);
5780	///
5781	/// // existing key
5782	/// map.entry_ref("poneyland").or_insert_with(\|\| `10`) = `2`;
5783	/// assert_eq!(map["poneyland"], `6`);
5784	/// ```
5785	#[cfg_attr(feature = "inline-more", inline)]
5786	pub fn or_insert_with<F: FnOnce() -> V>(self, default: F) -> &'a mut V
5787	where
5788	K: Hash + From<&'b Q>,
5789	S: BuildHasher,
5790	{
5791	match self {
5792	EntryRef::Occupied(entry) => entry.into_mut(),
5793	EntryRef::Vacant(entry) => entry.insert(default()),
5794	}
5795	}
5796
5797	/// Ensures a value is in the entry by inserting, if empty, the result of the default function.
5798	/// This method allows for generating key-derived values for insertion by providing the default
5799	/// function an access to the borrower form of the key.
5800	///
5801	/// # Examples
5802	///
5803	/// ```
5804	/// use hashbrown::HashMap;
5805	///
5806	/// let mut map: HashMap<String, usize> = HashMap::new();
5807	///
5808	/// // nonexistent key
5809	/// map.entry_ref("poneyland").or_insert_with_key(\|key\| key.chars().count());
5810	/// assert_eq!(map["poneyland"], `9`);
5811	///
5812	/// // existing key
5813	/// map.entry_ref("poneyland").or_insert_with_key(\|key\| key.chars().count() `10`) *= `2`;
5814	/// assert_eq!(map["poneyland"], `18`);
5815	/// ```
5816	#[cfg_attr(feature = "inline-more", inline)]
5817	pub fn or_insert_with_key<F: FnOnce(&Q) -> V>(self, default: F) -> &'a mut V
5818	where
5819	K: Hash + Borrow<Q> + From<&'b Q>,
5820	S: BuildHasher,
5821	{
5822	match self {
5823	EntryRef::Occupied(entry) => entry.into_mut(),
5824	EntryRef::Vacant(entry) => {
5825	let value = default(entry.key.as_ref());
5826	entry.insert(value)
5827	}
5828	}
5829	}
5830
5831	/// Returns a reference to this entry's key.
5832	///
5833	/// # Examples
5834	///
5835	/// ```
5836	/// use hashbrown::HashMap;
5837	///
5838	/// let mut map: HashMap<String, u32> = HashMap::new();
5839	/// map.entry_ref("poneyland").or_insert(`3`);
5840	/// // existing key
5841	/// assert_eq!(map.entry_ref("poneyland").key(), "poneyland");
5842	/// // nonexistent key
5843	/// assert_eq!(map.entry_ref("horseland").key(), "horseland");
5844	/// ```
5845	#[cfg_attr(feature = "inline-more", inline)]
5846	pub fn key(&self) -> &Q
5847	where
5848	K: Borrow<Q>,
5849	{
5850	match *self {
5851	EntryRef::Occupied(ref entry) => entry.key().borrow(),
5852	EntryRef::Vacant(ref entry) => entry.key(),
5853	}
5854	}
5855
5856	/// Provides in-place mutable access to an occupied entry before any
5857	/// potential inserts into the map.
5858	///
5859	/// # Examples
5860	///
5861	/// ```
5862	/// use hashbrown::HashMap;
5863	///
5864	/// let mut map: HashMap<String, u32> = HashMap::new();
5865	///
5866	/// map.entry_ref("poneyland")
5867	/// .and_modify(\|e\| { *e += `1` })
5868	/// .or_insert(`42`);
5869	/// assert_eq!(map["poneyland"], `42`);
5870	///
5871	/// map.entry_ref("poneyland")
5872	/// .and_modify(\|e\| { *e += `1` })
5873	/// .or_insert(`42`);
5874	/// assert_eq!(map["poneyland"], `43`);
5875	/// ```
5876	#[cfg_attr(feature = "inline-more", inline)]
5877	pub fn and_modify<F>(self, f: F) -> Self
5878	where
5879	F: FnOnce(&mut V),
5880	{
5881	match self {
5882	EntryRef::Occupied(mut entry) => {
5883	f(entry.get_mut());
5884	EntryRef::Occupied(entry)
5885	}
5886	EntryRef::Vacant(entry) => EntryRef::Vacant(entry),
5887	}
5888	}
5889
5890	/// Provides shared access to the key and owned access to the value of
5891	/// an occupied entry and allows to replace or remove it based on the
5892	/// value of the returned option.
5893	///
5894	/// # Examples
5895	///
5896	/// ```
5897	/// use hashbrown::HashMap;
5898	/// use hashbrown::hash_map::EntryRef;
5899	///
5900	/// let mut map: HashMap<String, u32> = HashMap::new();
5901	///
5902	/// let entry = map
5903	/// .entry_ref("poneyland")
5904	/// .and_replace_entry_with(\|_k, _v\| panic!());
5905	///
5906	/// match entry {
5907	/// EntryRef::Vacant(e) => {
5908	/// assert_eq!(e.key(), "poneyland");
5909	/// }
5910	/// EntryRef::Occupied(_) => panic!(),
5911	/// }
5912	///
5913	/// map.insert("poneyland".to_string(), `42`);
5914	///
5915	/// let entry = map
5916	/// .entry_ref("poneyland")
5917	/// .and_replace_entry_with(\|k, v\| {
5918	/// assert_eq!(k, "poneyland");
5919	/// assert_eq!(v, `42`);
5920	/// Some(v + `1`)
5921	/// });
5922	///
5923	/// match entry {
5924	/// EntryRef::Occupied(e) => {
5925	/// assert_eq!(e.key(), "poneyland");
5926	/// assert_eq!(e.get(), &`43`);
5927	/// }
5928	/// EntryRef::Vacant(_) => panic!(),
5929	/// }
5930	///
5931	/// assert_eq!(map["poneyland"], `43`);
5932	///
5933	/// let entry = map
5934	/// .entry_ref("poneyland")
5935	/// .and_replace_entry_with(\|_k, _v\| None);
5936	///
5937	/// match entry {
5938	/// EntryRef::Vacant(e) => assert_eq!(e.key(), "poneyland"),
5939	/// EntryRef::Occupied(_) => panic!(),
5940	/// }
5941	///
5942	/// assert!(!map.contains_key("poneyland"));
5943	/// ```
5944	#[cfg_attr(feature = "inline-more", inline)]
5945	pub fn and_replace_entry_with<F>(self, f: F) -> Self
5946	where
5947	F: FnOnce(&K, V) -> Option<V>,
5948	{
5949	match self {
5950	EntryRef::Occupied(entry) => entry.replace_entry_with(f),
5951	EntryRef::Vacant(_) => self,
5952	}
5953	}
5954	}
5955
5956	impl<'a, 'b, K, Q: ?Sized, V: Default, S, A: Allocator> EntryRef<'a, 'b, K, Q, V, S, A> {
5957	/// Ensures a value is in the entry by inserting the default value if empty,
5958	/// and returns a mutable reference to the value in the entry.
5959	///
5960	/// # Examples
5961	///
5962	/// ```
5963	/// use hashbrown::HashMap;
5964	///
5965	/// let mut map: HashMap<String, Option<u32>> = HashMap::new();
5966	///
5967	/// // nonexistent key
5968	/// map.entry_ref("poneyland").or_default();
5969	/// assert_eq!(map["poneyland"], None);
5970	///
5971	/// map.insert("horseland".to_string(), Some(`3`));
5972	///
5973	/// // existing key
5974	/// assert_eq!(map.entry_ref("horseland").or_default(), &mut Some(`3`));
5975	/// ```
5976	#[cfg_attr(feature = "inline-more", inline)]
5977	pub fn or_default(self) -> &'a mut V
5978	where
5979	K: Hash + From<&'b Q>,
5980	S: BuildHasher,
5981	{
5982	match self {
5983	EntryRef::Occupied(entry) => entry.into_mut(),
5984	EntryRef::Vacant(entry) => entry.insert(Default::default()),
5985	}
5986	}
5987	}
5988
5989	impl<'a, 'b, K, Q: ?Sized, V, S, A: Allocator> OccupiedEntryRef<'a, 'b, K, Q, V, S, A> {
5990	/// Gets a reference to the key in the entry.
5991	///
5992	/// # Examples
5993	///
5994	/// ```
5995	/// use hashbrown::hash_map::{EntryRef, HashMap};
5996	///
5997	/// let mut map: HashMap<String, u32> = HashMap::new();
5998	/// map.entry_ref("poneyland").or_insert(`12`);
5999	///
6000	/// match map.entry_ref("poneyland") {
6001	/// EntryRef::Vacant(_) => panic!(),
6002	/// EntryRef::Occupied(entry) => assert_eq!(entry.key(), "poneyland"),
6003	/// }
6004	/// ```
6005	#[cfg_attr(feature = "inline-more", inline)]
6006	pub fn key(&self) -> &K {
6007	unsafe { &self.elem.as_ref().0 }
6008	}
6009
6010	/// Take the ownership of the key and value from the map.
6011	/// Keeps the allocated memory for reuse.
6012	///
6013	/// # Examples
6014	///
6015	/// ```
6016	/// use hashbrown::HashMap;
6017	/// use hashbrown::hash_map::EntryRef;
6018	///
6019	/// let mut map: HashMap<String, u32> = HashMap::new();
6020	/// // The map is empty
6021	/// assert!(map.is_empty() && map.capacity() == `0`);
6022	///
6023	/// map.entry_ref("poneyland").or_insert(`12`);
6024	///
6025	/// if let EntryRef::Occupied(o) = map.entry_ref("poneyland") {
6026	/// // We delete the entry from the map.
6027	/// assert_eq!(o.remove_entry(), ("poneyland".to_owned(), `12`));
6028	/// }
6029	///
6030	/// assert_eq!(map.contains_key("poneyland"), `false`);
6031	/// // Now map hold none elements but capacity is equal to the old one
6032	/// assert!(map.is_empty());
6033	/// ```
6034	#[cfg_attr(feature = "inline-more", inline)]
6035	pub fn remove_entry(self) -> (K, V) {
6036	unsafe { self.table.table.remove(self.elem).0 }
6037	}
6038
6039	/// Gets a reference to the value in the entry.
6040	///
6041	/// # Examples
6042	///
6043	/// ```
6044	/// use hashbrown::HashMap;
6045	/// use hashbrown::hash_map::EntryRef;
6046	///
6047	/// let mut map: HashMap<String, u32> = HashMap::new();
6048	/// map.entry_ref("poneyland").or_insert(`12`);
6049	///
6050	/// match map.entry_ref("poneyland") {
6051	/// EntryRef::Vacant(_) => panic!(),
6052	/// EntryRef::Occupied(entry) => assert_eq!(entry.get(), &`12`),
6053	/// }
6054	/// ```
6055	#[cfg_attr(feature = "inline-more", inline)]
6056	pub fn get(&self) -> &V {
6057	unsafe { &self.elem.as_ref().1 }
6058	}
6059
6060	/// Gets a mutable reference to the value in the entry.
6061	///
6062	/// If you need a reference to the `OccupiedEntryRef` which may outlive the
6063	/// destruction of the `EntryRef` value, see [`into_mut`].
6064	///
6065	/// [`into_mut`]: #method.into_mut
6066	///
6067	/// # Examples
6068	///
6069	/// ```
6070	/// use hashbrown::HashMap;
6071	/// use hashbrown::hash_map::EntryRef;
6072	///
6073	/// let mut map: HashMap<String, u32> = HashMap::new();
6074	/// map.entry_ref("poneyland").or_insert(`12`);
6075	///
6076	/// assert_eq!(map["poneyland"], `12`);
6077	/// if let EntryRef::Occupied(mut o) = map.entry_ref("poneyland") {
6078	/// *o.get_mut() += `10`;
6079	/// assert_eq!(*o.get(), `22`);
6080	///
6081	/// // We can use the same Entry multiple times.
6082	/// *o.get_mut() += `2`;
6083	/// }
6084	///
6085	/// assert_eq!(map["poneyland"], `24`);
6086	/// ```
6087	#[cfg_attr(feature = "inline-more", inline)]
6088	pub fn get_mut(&mut self) -> &mut V {
6089	unsafe { &mut self.elem.as_mut().1 }
6090	}
6091
6092	/// Converts the OccupiedEntryRef into a mutable reference to the value in the entry
6093	/// with a lifetime bound to the map itself.
6094	///
6095	/// If you need multiple references to the `OccupiedEntryRef`, see [`get_mut`].
6096	///
6097	/// [`get_mut`]: #method.get_mut
6098	///
6099	/// # Examples
6100	///
6101	/// ```
6102	/// use hashbrown::hash_map::{EntryRef, HashMap};
6103	///
6104	/// let mut map: HashMap<String, u32> = HashMap::new();
6105	/// map.entry_ref("poneyland").or_insert(`12`);
6106	///
6107	/// let value: &mut u32;
6108	/// match map.entry_ref("poneyland") {
6109	/// EntryRef::Occupied(entry) => value = entry.into_mut(),
6110	/// EntryRef::Vacant(_) => panic!(),
6111	/// }
6112	/// *value += `10`;
6113	///
6114	/// assert_eq!(map["poneyland"], `22`);
6115	/// ```
6116	#[cfg_attr(feature = "inline-more", inline)]
6117	pub fn into_mut(self) -> &'a mut V {
6118	unsafe { &mut self.elem.as_mut().1 }
6119	}
6120
6121	/// Sets the value of the entry, and returns the entry's old value.
6122	///
6123	/// # Examples
6124	///
6125	/// ```
6126	/// use hashbrown::HashMap;
6127	/// use hashbrown::hash_map::EntryRef;
6128	///
6129	/// let mut map: HashMap<String, u32> = HashMap::new();
6130	/// map.entry_ref("poneyland").or_insert(`12`);
6131	///
6132	/// if let EntryRef::Occupied(mut o) = map.entry_ref("poneyland") {
6133	/// assert_eq!(o.insert(`15`), `12`);
6134	/// }
6135	///
6136	/// assert_eq!(map["poneyland"], `15`);
6137	/// ```
6138	#[cfg_attr(feature = "inline-more", inline)]
6139	pub fn insert(&mut self, value: V) -> V {
6140	mem::replace(self.get_mut(), value)
6141	}
6142
6143	/// Takes the value out of the entry, and returns it.
6144	/// Keeps the allocated memory for reuse.
6145	///
6146	/// # Examples
6147	///
6148	/// ```
6149	/// use hashbrown::HashMap;
6150	/// use hashbrown::hash_map::EntryRef;
6151	///
6152	/// let mut map: HashMap<String, u32> = HashMap::new();
6153	/// // The map is empty
6154	/// assert!(map.is_empty() && map.capacity() == `0`);
6155	///
6156	/// map.entry_ref("poneyland").or_insert(`12`);
6157	///
6158	/// if let EntryRef::Occupied(o) = map.entry_ref("poneyland") {
6159	/// assert_eq!(o.remove(), `12`);
6160	/// }
6161	///
6162	/// assert_eq!(map.contains_key("poneyland"), `false`);
6163	/// // Now map hold none elements but capacity is equal to the old one
6164	/// assert!(map.is_empty());
6165	/// ```
6166	#[cfg_attr(feature = "inline-more", inline)]
6167	pub fn remove(self) -> V {
6168	self.remove_entry().1
6169	}
6170
6171	/// Replaces the entry, returning the old key and value. The new key in the hash map will be
6172	/// the key used to create this entry.
6173	///
6174	/// # Panics
6175	///
6176	/// Will panic if this OccupiedEntryRef was created through [`EntryRef::insert`].
6177	///
6178	/// # Examples
6179	///
6180	/// ```
6181	/// use hashbrown::hash_map::{EntryRef, HashMap};
6182	/// use std::rc::Rc;
6183	///
6184	/// let mut map: HashMap<Rc<str>, u32> = HashMap::new();
6185	/// let key: Rc<str> = Rc::from("Stringthing");
6186	///
6187	/// map.insert(key.clone(), `15`);
6188	/// assert_eq!(Rc::strong_count(&key), `2`);
6189	///
6190	/// match map.entry_ref("Stringthing") {
6191	/// EntryRef::Occupied(entry) => {
6192	/// let (old_key, old_value): (Rc<str>, u32) = entry.replace_entry(`16`);
6193	/// assert!(Rc::ptr_eq(&key, &old_key) && old_value == `15`);
6194	/// }
6195	/// EntryRef::Vacant(_) => panic!(),
6196	/// }
6197	///
6198	/// assert_eq!(Rc::strong_count(&key), `1`);
6199	/// assert_eq!(map["Stringthing"], `16`);
6200	/// ```
6201	#[cfg_attr(feature = "inline-more", inline)]
6202	pub fn replace_entry(self, value: V) -> (K, V)
6203	where
6204	K: From<&'b Q>,
6205	{
6206	let entry = unsafe { self.elem.as_mut() };
6207
6208	let old_key = mem::replace(&mut entry.0, self.key.unwrap().into_owned());
6209	let old_value = mem::replace(&mut entry.1, value);
6210
6211	(old_key, old_value)
6212	}
6213
6214	/// Replaces the key in the hash map with the key used to create this entry.
6215	///
6216	/// # Panics
6217	///
6218	/// Will panic if this OccupiedEntryRef was created through [`EntryRef::insert`].
6219	///
6220	/// # Examples
6221	///
6222	/// ```
6223	/// use hashbrown::hash_map::{EntryRef, HashMap};
6224	/// use std::rc::Rc;
6225	///
6226	/// let mut map: HashMap<Rc<str>, usize> = HashMap::with_capacity(`6`);
6227	/// let mut keys: Vec<Rc<str>> = Vec::with_capacity(`6`);
6228	///
6229	/// for (value, key) in ["a", "b", "c", "d", "e", "f"].into_iter().enumerate() {
6230	/// let rc_key: Rc<str> = Rc::from(key);
6231	/// keys.push(rc_key.clone());
6232	/// map.insert(rc_key.clone(), value);
6233	/// }
6234	///
6235	/// assert!(keys.iter().all(\|key\| Rc::strong_count(key) == `2`));
6236	///
6237	/// // It doesn't matter that we kind of use a vector with the same keys,
6238	/// // because all keys will be newly created from the references
6239	/// reclaim_memory(&mut map, &keys);
6240	///
6241	/// assert!(keys.iter().all(\|key\| Rc::strong_count(key) == `1`));
6242	///
6243	/// fn reclaim_memory(map: &mut HashMap<Rc<str>, usize>, keys: &[Rc<str>]) {
6244	/// for key in keys {
6245	/// if let EntryRef::Occupied(entry) = map.entry_ref(key.as_ref()) {
6246	/// // Replaces the entry's key with our version of it in `keys`.
6247	/// entry.replace_key();
6248	/// }
6249	/// }
6250	/// }
6251	/// ```
6252	#[cfg_attr(feature = "inline-more", inline)]
6253	pub fn replace_key(self) -> K
6254	where
6255	K: From<&'b Q>,
6256	{
6257	let entry = unsafe { self.elem.as_mut() };
6258	mem::replace(&mut entry.0, self.key.unwrap().into_owned())
6259	}
6260
6261	/// Provides shared access to the key and owned access to the value of
6262	/// the entry and allows to replace or remove it based on the
6263	/// value of the returned option.
6264	///
6265	/// # Examples
6266	///
6267	/// ```
6268	/// use hashbrown::HashMap;
6269	/// use hashbrown::hash_map::EntryRef;
6270	///
6271	/// let mut map: HashMap<String, u32> = HashMap::new();
6272	/// map.insert("poneyland".to_string(), `42`);
6273	///
6274	/// let entry = match map.entry_ref("poneyland") {
6275	/// EntryRef::Occupied(e) => {
6276	/// e.replace_entry_with(\|k, v\| {
6277	/// assert_eq!(k, "poneyland");
6278	/// assert_eq!(v, `42`);
6279	/// Some(v + `1`)
6280	/// })
6281	/// }
6282	/// EntryRef::Vacant(_) => panic!(),
6283	/// };
6284	///
6285	/// match entry {
6286	/// EntryRef::Occupied(e) => {
6287	/// assert_eq!(e.key(), "poneyland");
6288	/// assert_eq!(e.get(), &`43`);
6289	/// }
6290	/// EntryRef::Vacant(_) => panic!(),
6291	/// }
6292	///
6293	/// assert_eq!(map["poneyland"], `43`);
6294	///
6295	/// let entry = match map.entry_ref("poneyland") {
6296	/// EntryRef::Occupied(e) => e.replace_entry_with(\|_k, _v\| None),
6297	/// EntryRef::Vacant(_) => panic!(),
6298	/// };
6299	///
6300	/// match entry {
6301	/// EntryRef::Vacant(e) => {
6302	/// assert_eq!(e.key(), "poneyland");
6303	/// }
6304	/// EntryRef::Occupied(_) => panic!(),
6305	/// }
6306	///
6307	/// assert!(!map.contains_key("poneyland"));
6308	/// ```
6309	#[cfg_attr(feature = "inline-more", inline)]
6310	pub fn replace_entry_with<F>(self, f: F) -> EntryRef<'a, 'b, K, Q, V, S, A>
6311	where
6312	F: FnOnce(&K, V) -> Option<V>,
6313	{
6314	unsafe {
6315	let mut spare_key = None;
6316
6317	self.table
6318	.table
6319	.replace_bucket_with(self.elem.clone(), \|(key, value)\| {
6320	if let Some(new_value) = f(&key, value) {
6321	Some((key, new_value))
6322	} else {
6323	spare_key = Some(KeyOrRef::Owned(key));
6324	None
6325	}
6326	});
6327
6328	if let Some(key) = spare_key {
6329	EntryRef::Vacant(VacantEntryRef {
6330	hash: self.hash,
6331	key,
6332	table: self.table,
6333	})
6334	} else {
6335	EntryRef::Occupied(self)
6336	}
6337	}
6338	}
6339	}
6340
6341	impl<'a, 'b, K, Q: ?Sized, V, S, A: Allocator> VacantEntryRef<'a, 'b, K, Q, V, S, A> {
6342	/// Gets a reference to the key that would be used when inserting a value
6343	/// through the `VacantEntryRef`.
6344	///
6345	/// # Examples
6346	///
6347	/// ```
6348	/// use hashbrown::HashMap;
6349	///
6350	/// let mut map: HashMap<String, u32> = HashMap::new();
6351	/// let key: &str = "poneyland";
6352	/// assert_eq!(map.entry_ref(key).key(), "poneyland");
6353	/// ```
6354	#[cfg_attr(feature = "inline-more", inline)]
6355	pub fn key(&self) -> &Q
6356	where
6357	K: Borrow<Q>,
6358	{
6359	self.key.as_ref()
6360	}
6361
6362	/// Take ownership of the key.
6363	///
6364	/// # Examples
6365	///
6366	/// ```
6367	/// use hashbrown::hash_map::{EntryRef, HashMap};
6368	///
6369	/// let mut map: HashMap<String, u32> = HashMap::new();
6370	/// let key: &str = "poneyland";
6371	///
6372	/// match map.entry_ref(key) {
6373	/// EntryRef::Occupied(_) => panic!(),
6374	/// EntryRef::Vacant(v) => assert_eq!(v.into_key(), "poneyland".to_owned()),
6375	/// }
6376	/// ```
6377	#[cfg_attr(feature = "inline-more", inline)]
6378	pub fn into_key(self) -> K
6379	where
6380	K: From<&'b Q>,
6381	{
6382	self.key.into_owned()
6383	}
6384
6385	/// Sets the value of the entry with the VacantEntryRef's key,
6386	/// and returns a mutable reference to it.
6387	///
6388	/// # Examples
6389	///
6390	/// ```
6391	/// use hashbrown::HashMap;
6392	/// use hashbrown::hash_map::EntryRef;
6393	///
6394	/// let mut map: HashMap<String, u32> = HashMap::new();
6395	/// let key: &str = "poneyland";
6396	///
6397	/// if let EntryRef::Vacant(o) = map.entry_ref(key) {
6398	/// o.insert(`37`);
6399	/// }
6400	/// assert_eq!(map["poneyland"], `37`);
6401	/// ```
6402	#[cfg_attr(feature = "inline-more", inline)]
6403	pub fn insert(self, value: V) -> &'a mut V
6404	where
6405	K: Hash + From<&'b Q>,
6406	S: BuildHasher,
6407	{
6408	let table = &mut self.table.table;
6409	let entry = table.insert_entry(
6410	self.hash,
6411	(self.key.into_owned(), value),
6412	make_hasher::<_, V, S>(&self.table.hash_builder),
6413	);
6414	&mut entry.1
6415	}
6416
6417	#[cfg_attr(feature = "inline-more", inline)]
6418	fn insert_entry(self, value: V) -> OccupiedEntryRef<'a, 'b, K, Q, V, S, A>
6419	where
6420	K: Hash + From<&'b Q>,
6421	S: BuildHasher,
6422	{
6423	let elem = self.table.table.insert(
6424	self.hash,
6425	(self.key.into_owned(), value),
6426	make_hasher::<_, V, S>(&self.table.hash_builder),
6427	);
6428	OccupiedEntryRef {
6429	hash: self.hash,
6430	key: None,
6431	elem,
6432	table: self.table,
6433	}
6434	}
6435	}
6436
6437	impl<K, V, S, A> FromIterator<(K, V)> for HashMap<K, V, S, A>
6438	where
6439	K: Eq + Hash,
6440	S: BuildHasher + Default,
6441	A: Default + Allocator,
6442	{
6443	#[cfg_attr(feature = "inline-more", inline)]
6444	fn from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> Self {
6445	let iter: ::IntoIter = iter.into_iter();
6446	let mut map: HashMap =
6447	Self::with_capacity_and_hasher_in(capacity:iter.size_hint().0, S::default(), A::default());
6448	iter.for_each(\|(k: K, v: V)\| {
6449	map.insert(k, v);
6450	});
6451	map
6452	}
6453	}
6454
6455	/// Inserts all new key-values from the iterator and replaces values with existing
6456	/// keys with new values returned from the iterator.
6457	impl<K, V, S, A> Extend<(K, V)> for HashMap<K, V, S, A>
6458	where
6459	K: Eq + Hash,
6460	S: BuildHasher,
6461	A: Allocator,
6462	{
6463	/// Inserts all new key-values from the iterator to existing `HashMap<K, V, S, A>`.
6464	/// Replace values with existing keys with new values returned from the iterator.
6465	///
6466	/// # Examples
6467	///
6468	/// ```
6469	/// use hashbrown::hash_map::HashMap;
6470	///
6471	/// let mut map = HashMap::new();
6472	/// map.insert(`1`, `100`);
6473	///
6474	/// let some_iter = [(`1`, `1`), (`2`, `2`)].into_iter();
6475	/// map.extend(some_iter);
6476	/// // Replace values with existing keys with new values returned from the iterator.
6477	/// // So that the map.get(&1) doesn't return Some(&100).
6478	/// assert_eq!(map.get(&`1`), Some(&`1`));
6479	///
6480	/// let some_vec: Vec<_> = vec![(`3`, `3`), (`4`, `4`)];
6481	/// map.extend(some_vec);
6482	///
6483	/// let some_arr = [(`5`, `5`), (`6`, `6`)];
6484	/// map.extend(some_arr);
6485	/// let old_map_len = map.len();
6486	///
6487	/// // You can also extend from another HashMap
6488	/// let mut new_map = HashMap::new();
6489	/// new_map.extend(map);
6490	/// assert_eq!(new_map.len(), old_map_len);
6491	///
6492	/// let mut vec: Vec<_> = new_map.into_iter().collect();
6493	/// // The `IntoIter` iterator produces items in arbitrary order, so the
6494	/// // items must be sorted to test them against a sorted array.
6495	/// vec.sort_unstable();
6496	/// assert_eq!(vec, [(`1`, `1`), (`2`, `2`), (`3`, `3`), (`4`, `4`), (`5`, `5`), (`6`, `6`)]);
6497	/// ```
6498	#[cfg_attr(feature = "inline-more", inline)]
6499	fn extend<T: IntoIterator<Item = (K, V)>>(&mut self, iter: T) {
6500	// Keys may be already present or show multiple times in the iterator.
6501	// Reserve the entire hint lower bound if the map is empty.
6502	// Otherwise reserve half the hint (rounded up), so the map
6503	// will only resize twice in the worst case.
6504	let iter = iter.into_iter();
6505	let reserve = if self.is_empty() {
6506	iter.size_hint().0
6507	} else {
6508	(iter.size_hint().0 + `1`) / `2`
6509	};
6510	self.reserve(reserve);
6511	iter.for_each(move \|(k, v)\| {
6512	self.insert(k, v);
6513	});
6514	}
6515
6516	#[inline]
6517	#[cfg(feature = "nightly")]
6518	fn extend_one(&mut self, (k, v): (K, V)) {
6519	self.insert(k, v);
6520	}
6521
6522	#[inline]
6523	#[cfg(feature = "nightly")]
6524	fn extend_reserve(&mut self, additional: usize) {
6525	// Keys may be already present or show multiple times in the iterator.
6526	// Reserve the entire hint lower bound if the map is empty.
6527	// Otherwise reserve half the hint (rounded up), so the map
6528	// will only resize twice in the worst case.
6529	let reserve = if self.is_empty() {
6530	additional
6531	} else {
6532	(additional + `1`) / `2`
6533	};
6534	self.reserve(reserve);
6535	}
6536	}
6537
6538	/// Inserts all new key-values from the iterator and replaces values with existing
6539	/// keys with new values returned from the iterator.
6540	impl<'a, K, V, S, A> Extend<(&'a K, &'a V)> for HashMap<K, V, S, A>
6541	where
6542	K: Eq + Hash + Copy,
6543	V: Copy,
6544	S: BuildHasher,
6545	A: Allocator,
6546	{
6547	/// Inserts all new key-values from the iterator to existing `HashMap<K, V, S, A>`.
6548	/// Replace values with existing keys with new values returned from the iterator.
6549	/// The keys and values must implement [`Copy`] trait.
6550	///
6551	/// [`Copy`]: https://doc.rust-lang.org/core/marker/trait.Copy.html
6552	///
6553	/// # Examples
6554	///
6555	/// ```
6556	/// use hashbrown::hash_map::HashMap;
6557	///
6558	/// let mut map = HashMap::new();
6559	/// map.insert(`1`, `100`);
6560	///
6561	/// let arr = [(`1`, `1`), (`2`, `2`)];
6562	/// let some_iter = arr.iter().map(\|(k, v)\| (k, v));
6563	/// map.extend(some_iter);
6564	/// // Replace values with existing keys with new values returned from the iterator.
6565	/// // So that the map.get(&1) doesn't return Some(&100).
6566	/// assert_eq!(map.get(&`1`), Some(&`1`));
6567	///
6568	/// let some_vec: Vec<_> = vec![(`3`, `3`), (`4`, `4`)];
6569	/// map.extend(some_vec.iter().map(\|(k, v)\| (k, v)));
6570	///
6571	/// let some_arr = [(`5`, `5`), (`6`, `6`)];
6572	/// map.extend(some_arr.iter().map(\|(k, v)\| (k, v)));
6573	///
6574	/// // You can also extend from another HashMap
6575	/// let mut new_map = HashMap::new();
6576	/// new_map.extend(&map);
6577	/// assert_eq!(new_map, map);
6578	///
6579	/// let mut vec: Vec<_> = new_map.into_iter().collect();
6580	/// // The `IntoIter` iterator produces items in arbitrary order, so the
6581	/// // items must be sorted to test them against a sorted array.
6582	/// vec.sort_unstable();
6583	/// assert_eq!(vec, [(`1`, `1`), (`2`, `2`), (`3`, `3`), (`4`, `4`), (`5`, `5`), (`6`, `6`)]);
6584	/// ```
6585	#[cfg_attr(feature = "inline-more", inline)]
6586	fn extend<T: IntoIterator<Item = (&'a K, &'a V)>>(&mut self, iter: T) {
6587	self.extend(iter.into_iter().map(\|(&key, &value)\| (key, value)));
6588	}
6589
6590	#[inline]
6591	#[cfg(feature = "nightly")]
6592	fn extend_one(&mut self, (k, v): (&'a K, &'a V)) {
6593	self.insert(k, v);
6594	}
6595
6596	#[inline]
6597	#[cfg(feature = "nightly")]
6598	fn extend_reserve(&mut self, additional: usize) {
6599	Extend::<(K, V)>::extend_reserve(self, additional);
6600	}
6601	}
6602
6603	/// Inserts all new key-values from the iterator and replaces values with existing
6604	/// keys with new values returned from the iterator.
6605	impl<'a, K, V, S, A> Extend<&'a (K, V)> for HashMap<K, V, S, A>
6606	where
6607	K: Eq + Hash + Copy,
6608	V: Copy,
6609	S: BuildHasher,
6610	A: Allocator,
6611	{
6612	/// Inserts all new key-values from the iterator to existing `HashMap<K, V, S, A>`.
6613	/// Replace values with existing keys with new values returned from the iterator.
6614	/// The keys and values must implement [`Copy`] trait.
6615	///
6616	/// [`Copy`]: https://doc.rust-lang.org/core/marker/trait.Copy.html
6617	///
6618	/// # Examples
6619	///
6620	/// ```
6621	/// use hashbrown::hash_map::HashMap;
6622	///
6623	/// let mut map = HashMap::new();
6624	/// map.insert(`1`, `100`);
6625	///
6626	/// let arr = [(`1`, `1`), (`2`, `2`)];
6627	/// let some_iter = arr.iter();
6628	/// map.extend(some_iter);
6629	/// // Replace values with existing keys with new values returned from the iterator.
6630	/// // So that the map.get(&1) doesn't return Some(&100).
6631	/// assert_eq!(map.get(&`1`), Some(&`1`));
6632	///
6633	/// let some_vec: Vec<_> = vec![(`3`, `3`), (`4`, `4`)];
6634	/// map.extend(&some_vec);
6635	///
6636	/// let some_arr = [(`5`, `5`), (`6`, `6`)];
6637	/// map.extend(&some_arr);
6638	///
6639	/// let mut vec: Vec<_> = map.into_iter().collect();
6640	/// // The `IntoIter` iterator produces items in arbitrary order, so the
6641	/// // items must be sorted to test them against a sorted array.
6642	/// vec.sort_unstable();
6643	/// assert_eq!(vec, [(`1`, `1`), (`2`, `2`), (`3`, `3`), (`4`, `4`), (`5`, `5`), (`6`, `6`)]);
6644	/// ```
6645	#[cfg_attr(feature = "inline-more", inline)]
6646	fn extend<T: IntoIterator<Item = &'a (K, V)>>(&mut self, iter: T) {
6647	self.extend(iter.into_iter().map(\|&(key, value)\| (key, value)));
6648	}
6649
6650	#[inline]
6651	#[cfg(feature = "nightly")]
6652	fn extend_one(&mut self, &(k, v): &'a (K, V)) {
6653	self.insert(k, v);
6654	}
6655
6656	#[inline]
6657	#[cfg(feature = "nightly")]
6658	fn extend_reserve(&mut self, additional: usize) {
6659	Extend::<(K, V)>::extend_reserve(self, additional);
6660	}
6661	}
6662
6663	#[allow(dead_code)]
6664	fn assert_covariance() {
6665	fn map_key<'new>(v: HashMap<&'static str, u8>) -> HashMap<&'new str, u8> {
6666	v
6667	}
6668	fn map_val<'new>(v: HashMap<u8, &'static str>) -> HashMap<u8, &'new str> {
6669	v
6670	}
6671	fn iter_key<'a, 'new>(v: Iter<'a, &'static str, u8>) -> Iter<'a, &'new str, u8> {
6672	v
6673	}
6674	fn iter_val<'a, 'new>(v: Iter<'a, u8, &'static str>) -> Iter<'a, u8, &'new str> {
6675	v
6676	}
6677	fn into_iter_key<'new, A: Allocator>(
6678	v: IntoIter<&'static str, u8, A>,
6679	) -> IntoIter<&'new str, u8, A> {
6680	v
6681	}
6682	fn into_iter_val<'new, A: Allocator>(
6683	v: IntoIter<u8, &'static str, A>,
6684	) -> IntoIter<u8, &'new str, A> {
6685	v
6686	}
6687	fn keys_key<'a, 'new>(v: Keys<'a, &'static str, u8>) -> Keys<'a, &'new str, u8> {
6688	v
6689	}
6690	fn keys_val<'a, 'new>(v: Keys<'a, u8, &'static str>) -> Keys<'a, u8, &'new str> {
6691	v
6692	}
6693	fn values_key<'a, 'new>(v: Values<'a, &'static str, u8>) -> Values<'a, &'new str, u8> {
6694	v
6695	}
6696	fn values_val<'a, 'new>(v: Values<'a, u8, &'static str>) -> Values<'a, u8, &'new str> {
6697	v
6698	}
6699	fn drain<'new>(
6700	d: Drain<'static, &'static str, &'static str>,
6701	) -> Drain<'new, &'new str, &'new str> {
6702	d
6703	}
6704	}
6705
6706	#[cfg(test)]
6707	mod test_map {
6708	use super::DefaultHashBuilder;
6709	use super::Entry::{Occupied, Vacant};
6710	use super::EntryRef;
6711	use super::{HashMap, RawEntryMut};
6712	use alloc::string::{String, ToString};
6713	use alloc::sync::Arc;
6714	use allocator_api2::alloc::{AllocError, Allocator, Global};
6715	use core::alloc::Layout;
6716	use core::ptr::NonNull;
6717	use core::sync::atomic::{AtomicI8, Ordering};
6718	use rand::{rngs::SmallRng, Rng, SeedableRng};
6719	use std::borrow::ToOwned;
6720	use std::cell::RefCell;
6721	use std::usize;
6722	use std::vec::Vec;
6723
6724	#[test]
6725	fn test_zero_capacities() {
6726	type HM = HashMap<i32, i32>;
6727
6728	let m = HM::new();
6729	assert_eq!(m.capacity(), `0`);
6730
6731	let m = HM::default();
6732	assert_eq!(m.capacity(), `0`);
6733
6734	let m = HM::with_hasher(DefaultHashBuilder::default());
6735	assert_eq!(m.capacity(), `0`);
6736
6737	let m = HM::with_capacity(`0`);
6738	assert_eq!(m.capacity(), `0`);
6739
6740	let m = HM::with_capacity_and_hasher(`0`, DefaultHashBuilder::default());
6741	assert_eq!(m.capacity(), `0`);
6742
6743	let mut m = HM::new();
6744	m.insert(`1`, `1`);
6745	m.insert(`2`, `2`);
6746	m.remove(&`1`);
6747	m.remove(&`2`);
6748	m.shrink_to_fit();
6749	assert_eq!(m.capacity(), `0`);
6750
6751	let mut m = HM::new();
6752	m.reserve(`0`);
6753	assert_eq!(m.capacity(), `0`);
6754	}
6755
6756	#[test]
6757	fn test_create_capacity_zero() {
6758	let mut m = HashMap::with_capacity(`0`);
6759
6760	assert!(m.insert(`1`, `1`).is_none());
6761
6762	assert!(m.contains_key(&`1`));
6763	assert!(!m.contains_key(&`0`));
6764	}
6765
6766	#[test]
6767	fn test_insert() {
6768	let mut m = HashMap::new();
6769	assert_eq!(m.len(), `0`);
6770	assert!(m.insert(`1`, `2`).is_none());
6771	assert_eq!(m.len(), `1`);
6772	assert!(m.insert(`2`, `4`).is_none());
6773	assert_eq!(m.len(), `2`);
6774	assert_eq!(*m.get(&`1`).unwrap(), `2`);
6775	assert_eq!(*m.get(&`2`).unwrap(), `4`);
6776	}
6777
6778	#[test]
6779	fn test_clone() {
6780	let mut m = HashMap::new();
6781	assert_eq!(m.len(), `0`);
6782	assert!(m.insert(`1`, `2`).is_none());
6783	assert_eq!(m.len(), `1`);
6784	assert!(m.insert(`2`, `4`).is_none());
6785	assert_eq!(m.len(), `2`);
6786	#[allow(clippy::redundant_clone)]
6787	let m2 = m.clone();
6788	assert_eq!(*m2.get(&`1`).unwrap(), `2`);
6789	assert_eq!(*m2.get(&`2`).unwrap(), `4`);
6790	assert_eq!(m2.len(), `2`);
6791	}
6792
6793	#[test]
6794	fn test_clone_from() {
6795	let mut m = HashMap::new();
6796	let mut m2 = HashMap::new();
6797	assert_eq!(m.len(), `0`);
6798	assert!(m.insert(`1`, `2`).is_none());
6799	assert_eq!(m.len(), `1`);
6800	assert!(m.insert(`2`, `4`).is_none());
6801	assert_eq!(m.len(), `2`);
6802	m2.clone_from(&m);
6803	assert_eq!(*m2.get(&`1`).unwrap(), `2`);
6804	assert_eq!(*m2.get(&`2`).unwrap(), `4`);
6805	assert_eq!(m2.len(), `2`);
6806	}
6807
6808	thread_local! { static DROP_VECTOR: RefCell<Vec<i32>> = const { RefCell::new(Vec::new()) } }
6809
6810	#[derive(Hash, PartialEq, Eq)]
6811	struct Droppable {
6812	k: usize,
6813	}
6814
6815	impl Droppable {
6816	fn new(k: usize) -> Droppable {
6817	DROP_VECTOR.with(\|slot\| {
6818	slot.borrow_mut()[k] += `1`;
6819	});
6820
6821	Droppable { k }
6822	}
6823	}
6824
6825	impl Drop for Droppable {
6826	fn drop(&mut self) {
6827	DROP_VECTOR.with(\|slot\| {
6828	slot.borrow_mut()[self.k] -= `1`;
6829	});
6830	}
6831	}
6832
6833	impl Clone for Droppable {
6834	fn clone(&self) -> Self {
6835	Droppable::new(self.k)
6836	}
6837	}
6838
6839	#[test]
6840	fn test_drops() {
6841	DROP_VECTOR.with(\|slot\| {
6842	*slot.borrow_mut() = vec![`0`; `200`];
6843	});
6844
6845	{
6846	let mut m = HashMap::new();
6847
6848	DROP_VECTOR.with(\|v\| {
6849	for i in `0`..`200` {
6850	assert_eq!(v.borrow()[i], `0`);
6851	}
6852	});
6853
6854	for i in `0`..`100` {
6855	let d1 = Droppable::new(i);
6856	let d2 = Droppable::new(i + `100`);
6857	m.insert(d1, d2);
6858	}
6859
6860	DROP_VECTOR.with(\|v\| {
6861	for i in `0`..`200` {
6862	assert_eq!(v.borrow()[i], `1`);
6863	}
6864	});
6865
6866	for i in `0`..`50` {
6867	let k = Droppable::new(i);
6868	let v = m.remove(&k);
6869
6870	assert!(v.is_some());
6871
6872	DROP_VECTOR.with(\|v\| {
6873	assert_eq!(v.borrow()[i], `1`);
6874	assert_eq!(v.borrow()[i + `100`], `1`);
6875	});
6876	}
6877
6878	DROP_VECTOR.with(\|v\| {
6879	for i in `0`..`50` {
6880	assert_eq!(v.borrow()[i], `0`);
6881	assert_eq!(v.borrow()[i + `100`], `0`);
6882	}
6883
6884	for i in `50`..`100` {
6885	assert_eq!(v.borrow()[i], `1`);
6886	assert_eq!(v.borrow()[i + `100`], `1`);
6887	}
6888	});
6889	}
6890
6891	DROP_VECTOR.with(\|v\| {
6892	for i in `0`..`200` {
6893	assert_eq!(v.borrow()[i], `0`);
6894	}
6895	});
6896	}
6897
6898	#[test]
6899	fn test_into_iter_drops() {
6900	DROP_VECTOR.with(\|v\| {
6901	*v.borrow_mut() = vec![`0`; `200`];
6902	});
6903
6904	let hm = {
6905	let mut hm = HashMap::new();
6906
6907	DROP_VECTOR.with(\|v\| {
6908	for i in `0`..`200` {
6909	assert_eq!(v.borrow()[i], `0`);
6910	}
6911	});
6912
6913	for i in `0`..`100` {
6914	let d1 = Droppable::new(i);
6915	let d2 = Droppable::new(i + `100`);
6916	hm.insert(d1, d2);
6917	}
6918
6919	DROP_VECTOR.with(\|v\| {
6920	for i in `0`..`200` {
6921	assert_eq!(v.borrow()[i], `1`);
6922	}
6923	});
6924
6925	hm
6926	};
6927
6928	// By the way, ensure that cloning doesn't screw up the dropping.
6929	drop(hm.clone());
6930
6931	{
6932	let mut half = hm.into_iter().take(`50`);
6933
6934	DROP_VECTOR.with(\|v\| {
6935	for i in `0`..`200` {
6936	assert_eq!(v.borrow()[i], `1`);
6937	}
6938	});
6939
6940	for _ in half.by_ref() {}
6941
6942	DROP_VECTOR.with(\|v\| {
6943	let nk = (`0`..`100`).filter(\|&i\| v.borrow()[i] == `1`).count();
6944
6945	let nv = (`0`..`100`).filter(\|&i\| v.borrow()[i + `100`] == `1`).count();
6946
6947	assert_eq!(nk, `50`);
6948	assert_eq!(nv, `50`);
6949	});
6950	};
6951
6952	DROP_VECTOR.with(\|v\| {
6953	for i in `0`..`200` {
6954	assert_eq!(v.borrow()[i], `0`);
6955	}
6956	});
6957	}
6958
6959	#[test]
6960	fn test_empty_remove() {
6961	let mut m: HashMap<i32, bool> = HashMap::new();
6962	assert_eq!(m.remove(&`0`), None);
6963	}
6964
6965	#[test]
6966	fn test_empty_entry() {
6967	let mut m: HashMap<i32, bool> = HashMap::new();
6968	match m.entry(`0`) {
6969	Occupied(_) => panic!(),
6970	Vacant(_) => {}
6971	}
6972	assert!(*m.entry(`0`).or_insert(`true`));
6973	assert_eq!(m.len(), `1`);
6974	}
6975
6976	#[test]
6977	fn test_empty_entry_ref() {
6978	let mut m: HashMap<std::string::String, bool> = HashMap::new();
6979	match m.entry_ref("poneyland") {
6980	EntryRef::Occupied(_) => panic!(),
6981	EntryRef::Vacant(_) => {}
6982	}
6983	assert!(*m.entry_ref("poneyland").or_insert(`true`));
6984	assert_eq!(m.len(), `1`);
6985	}
6986
6987	#[test]
6988	fn test_empty_iter() {
6989	let mut m: HashMap<i32, bool> = HashMap::new();
6990	assert_eq!(m.drain().next(), None);
6991	assert_eq!(m.keys().next(), None);
6992	assert_eq!(m.values().next(), None);
6993	assert_eq!(m.values_mut().next(), None);
6994	assert_eq!(m.iter().next(), None);
6995	assert_eq!(m.iter_mut().next(), None);
6996	assert_eq!(m.len(), `0`);
6997	assert!(m.is_empty());
6998	assert_eq!(m.into_iter().next(), None);
6999	}
7000
7001	#[test]
7002	#[cfg_attr(miri, ignore)] // FIXME: takes too long
7003	fn test_lots_of_insertions() {
7004	let mut m = HashMap::new();
7005
7006	// Try this a few times to make sure we never screw up the hashmap's
7007	// internal state.
7008	for _ in `0`..`10` {
7009	assert!(m.is_empty());
7010
7011	for i in `1`..`1001` {
7012	assert!(m.insert(i, i).is_none());
7013
7014	for j in `1`..=i {
7015	let r = m.get(&j);
7016	assert_eq!(r, Some(&j));
7017	}
7018
7019	for j in i + `1`..`1001` {
7020	let r = m.get(&j);
7021	assert_eq!(r, None);
7022	}
7023	}
7024
7025	for i in `1001`..`2001` {
7026	assert!(!m.contains_key(&i));
7027	}
7028
7029	// remove forwards
7030	for i in `1`..`1001` {
7031	assert!(m.remove(&i).is_some());
7032
7033	for j in `1`..=i {
7034	assert!(!m.contains_key(&j));
7035	}
7036
7037	for j in i + `1`..`1001` {
7038	assert!(m.contains_key(&j));
7039	}
7040	}
7041
7042	for i in `1`..`1001` {
7043	assert!(!m.contains_key(&i));
7044	}
7045
7046	for i in `1`..`1001` {
7047	assert!(m.insert(i, i).is_none());
7048	}
7049
7050	// remove backwards
7051	for i in (`1`..`1001`).rev() {
7052	assert!(m.remove(&i).is_some());
7053
7054	for j in i..`1001` {
7055	assert!(!m.contains_key(&j));
7056	}
7057
7058	for j in `1`..i {
7059	assert!(m.contains_key(&j));
7060	}
7061	}
7062	}
7063	}
7064
7065	#[test]
7066	fn test_find_mut() {
7067	let mut m = HashMap::new();
7068	assert!(m.insert(`1`, `12`).is_none());
7069	assert!(m.insert(`2`, `8`).is_none());
7070	assert!(m.insert(`5`, `14`).is_none());
7071	let new = `100`;
7072	match m.get_mut(&`5`) {
7073	None => panic!(),
7074	Some(x) => *x = new,
7075	}
7076	assert_eq!(m.get(&`5`), Some(&new));
7077	}
7078
7079	#[test]
7080	fn test_insert_overwrite() {
7081	let mut m = HashMap::new();
7082	assert!(m.insert(`1`, `2`).is_none());
7083	assert_eq!(*m.get(&`1`).unwrap(), `2`);
7084	assert!(m.insert(`1`, `3`).is_some());
7085	assert_eq!(*m.get(&`1`).unwrap(), `3`);
7086	}
7087
7088	#[test]
7089	fn test_insert_conflicts() {
7090	let mut m = HashMap::with_capacity(`4`);
7091	assert!(m.insert(`1`, `2`).is_none());
7092	assert!(m.insert(`5`, `3`).is_none());
7093	assert!(m.insert(`9`, `4`).is_none());
7094	assert_eq!(*m.get(&`9`).unwrap(), `4`);
7095	assert_eq!(*m.get(&`5`).unwrap(), `3`);
7096	assert_eq!(*m.get(&`1`).unwrap(), `2`);
7097	}
7098
7099	#[test]
7100	fn test_conflict_remove() {
7101	let mut m = HashMap::with_capacity(`4`);
7102	assert!(m.insert(`1`, `2`).is_none());
7103	assert_eq!(*m.get(&`1`).unwrap(), `2`);
7104	assert!(m.insert(`5`, `3`).is_none());
7105	assert_eq!(*m.get(&`1`).unwrap(), `2`);
7106	assert_eq!(*m.get(&`5`).unwrap(), `3`);
7107	assert!(m.insert(`9`, `4`).is_none());
7108	assert_eq!(*m.get(&`1`).unwrap(), `2`);
7109	assert_eq!(*m.get(&`5`).unwrap(), `3`);
7110	assert_eq!(*m.get(&`9`).unwrap(), `4`);
7111	assert!(m.remove(&`1`).is_some());
7112	assert_eq!(*m.get(&`9`).unwrap(), `4`);
7113	assert_eq!(*m.get(&`5`).unwrap(), `3`);
7114	}
7115
7116	#[test]
7117	fn test_insert_unique_unchecked() {
7118	let mut map = HashMap::new();
7119	let (k1, v1) = map.insert_unique_unchecked(`10`, `11`);
7120	assert_eq!((&`10`, &mut `11`), (k1, v1));
7121	let (k2, v2) = map.insert_unique_unchecked(`20`, `21`);
7122	assert_eq!((&`20`, &mut `21`), (k2, v2));
7123	assert_eq!(Some(&`11`), map.get(&`10`));
7124	assert_eq!(Some(&`21`), map.get(&`20`));
7125	assert_eq!(None, map.get(&`30`));
7126	}
7127
7128	#[test]
7129	fn test_is_empty() {
7130	let mut m = HashMap::with_capacity(`4`);
7131	assert!(m.insert(`1`, `2`).is_none());
7132	assert!(!m.is_empty());
7133	assert!(m.remove(&`1`).is_some());
7134	assert!(m.is_empty());
7135	}
7136
7137	#[test]
7138	fn test_remove() {
7139	let mut m = HashMap::new();
7140	m.insert(`1`, `2`);
7141	assert_eq!(m.remove(&`1`), Some(`2`));
7142	assert_eq!(m.remove(&`1`), None);
7143	}
7144
7145	#[test]
7146	fn test_remove_entry() {
7147	let mut m = HashMap::new();
7148	m.insert(`1`, `2`);
7149	assert_eq!(m.remove_entry(&`1`), Some((`1`, `2`)));
7150	assert_eq!(m.remove(&`1`), None);
7151	}
7152
7153	#[test]
7154	fn test_iterate() {
7155	let mut m = HashMap::with_capacity(`4`);
7156	for i in `0`..`32` {
7157	assert!(m.insert(i, i * `2`).is_none());
7158	}
7159	assert_eq!(m.len(), `32`);
7160
7161	let mut observed: u32 = `0`;
7162
7163	for (k, v) in &m {
7164	assert_eq!(v, k * `2`);
7165	observed \|= `1` << *k;
7166	}
7167	assert_eq!(observed, `0xFFFF_FFFF`);
7168	}
7169
7170	#[test]
7171	fn test_keys() {
7172	let vec = vec![(`1`, 'a'), (`2`, 'b'), (`3`, 'c')];
7173	let map: HashMap<_, _> = vec.into_iter().collect();
7174	let keys: Vec<_> = map.keys().copied().collect();
7175	assert_eq!(keys.len(), `3`);
7176	assert!(keys.contains(&`1`));
7177	assert!(keys.contains(&`2`));
7178	assert!(keys.contains(&`3`));
7179	}
7180
7181	#[test]
7182	fn test_values() {
7183	let vec = vec![(`1`, 'a'), (`2`, 'b'), (`3`, 'c')];
7184	let map: HashMap<_, _> = vec.into_iter().collect();
7185	let values: Vec<_> = map.values().copied().collect();
7186	assert_eq!(values.len(), `3`);
7187	assert!(values.contains(&'a'));
7188	assert!(values.contains(&'b'));
7189	assert!(values.contains(&'c'));
7190	}
7191
7192	#[test]
7193	fn test_values_mut() {
7194	let vec = vec![(`1`, `1`), (`2`, `2`), (`3`, `3`)];
7195	let mut map: HashMap<_, _> = vec.into_iter().collect();
7196	for value in map.values_mut() {
7197	value = `2`;
7198	}
7199	let values: Vec<_> = map.values().copied().collect();
7200	assert_eq!(values.len(), `3`);
7201	assert!(values.contains(&`2`));
7202	assert!(values.contains(&`4`));
7203	assert!(values.contains(&`6`));
7204	}
7205
7206	#[test]
7207	fn test_into_keys() {
7208	let vec = vec![(`1`, 'a'), (`2`, 'b'), (`3`, 'c')];
7209	let map: HashMap<_, _> = vec.into_iter().collect();
7210	let keys: Vec<_> = map.into_keys().collect();
7211
7212	assert_eq!(keys.len(), `3`);
7213	assert!(keys.contains(&`1`));
7214	assert!(keys.contains(&`2`));
7215	assert!(keys.contains(&`3`));
7216	}
7217
7218	#[test]
7219	fn test_into_values() {
7220	let vec = vec![(`1`, 'a'), (`2`, 'b'), (`3`, 'c')];
7221	let map: HashMap<_, _> = vec.into_iter().collect();
7222	let values: Vec<_> = map.into_values().collect();
7223
7224	assert_eq!(values.len(), `3`);
7225	assert!(values.contains(&'a'));
7226	assert!(values.contains(&'b'));
7227	assert!(values.contains(&'c'));
7228	}
7229
7230	#[test]
7231	fn test_find() {
7232	let mut m = HashMap::new();
7233	assert!(m.get(&`1`).is_none());
7234	m.insert(`1`, `2`);
7235	match m.get(&`1`) {
7236	None => panic!(),
7237	Some(v) => assert_eq!(*v, `2`),
7238	}
7239	}
7240
7241	#[test]
7242	fn test_eq() {
7243	let mut m1 = HashMap::new();
7244	m1.insert(`1`, `2`);
7245	m1.insert(`2`, `3`);
7246	m1.insert(`3`, `4`);
7247
7248	let mut m2 = HashMap::new();
7249	m2.insert(`1`, `2`);
7250	m2.insert(`2`, `3`);
7251
7252	assert!(m1 != m2);
7253
7254	m2.insert(`3`, `4`);
7255
7256	assert_eq!(m1, m2);
7257	}
7258
7259	#[test]
7260	fn test_show() {
7261	let mut map = HashMap::new();
7262	let empty: HashMap<i32, i32> = HashMap::new();
7263
7264	map.insert(`1`, `2`);
7265	map.insert(`3`, `4`);
7266
7267	let map_str = format!("{map:?}");
7268
7269	assert!(map_str == "{1: 2, 3: 4}" \|\| map_str == "{3: 4, 1: 2}");
7270	assert_eq!(format!("{empty:?}"), "{}");
7271	}
7272
7273	#[test]
7274	fn test_expand() {
7275	let mut m = HashMap::new();
7276
7277	assert_eq!(m.len(), `0`);
7278	assert!(m.is_empty());
7279
7280	let mut i = `0`;
7281	let old_raw_cap = m.raw_capacity();
7282	while old_raw_cap == m.raw_capacity() {
7283	m.insert(i, i);
7284	i += `1`;
7285	}
7286
7287	assert_eq!(m.len(), i);
7288	assert!(!m.is_empty());
7289	}
7290
7291	#[test]
7292	fn test_behavior_resize_policy() {
7293	let mut m = HashMap::new();
7294
7295	assert_eq!(m.len(), `0`);
7296	assert_eq!(m.raw_capacity(), `1`);
7297	assert!(m.is_empty());
7298
7299	m.insert(`0`, `0`);
7300	m.remove(&`0`);
7301	assert!(m.is_empty());
7302	let initial_raw_cap = m.raw_capacity();
7303	m.reserve(initial_raw_cap);
7304	let raw_cap = m.raw_capacity();
7305
7306	assert_eq!(raw_cap, initial_raw_cap * `2`);
7307
7308	let mut i = `0`;
7309	for _ in `0`..raw_cap * `3` / `4` {
7310	m.insert(i, i);
7311	i += `1`;
7312	}
7313	// three quarters full
7314
7315	assert_eq!(m.len(), i);
7316	assert_eq!(m.raw_capacity(), raw_cap);
7317
7318	for _ in `0`..raw_cap / `4` {
7319	m.insert(i, i);
7320	i += `1`;
7321	}
7322	// half full
7323
7324	let new_raw_cap = m.raw_capacity();
7325	assert_eq!(new_raw_cap, raw_cap * `2`);
7326
7327	for _ in `0`..raw_cap / `2` - `1` {
7328	i -= `1`;
7329	m.remove(&i);
7330	assert_eq!(m.raw_capacity(), new_raw_cap);
7331	}
7332	// A little more than one quarter full.
7333	m.shrink_to_fit();
7334	assert_eq!(m.raw_capacity(), raw_cap);
7335	// again, a little more than half full
7336	for _ in `0`..raw_cap / `2` {
7337	i -= `1`;
7338	m.remove(&i);
7339	}
7340	m.shrink_to_fit();
7341
7342	assert_eq!(m.len(), i);
7343	assert!(!m.is_empty());
7344	assert_eq!(m.raw_capacity(), initial_raw_cap);
7345	}
7346
7347	#[test]
7348	fn test_reserve_shrink_to_fit() {
7349	let mut m = HashMap::new();
7350	m.insert(`0`, `0`);
7351	m.remove(&`0`);
7352	assert!(m.capacity() >= m.len());
7353	for i in `0`..`128` {
7354	m.insert(i, i);
7355	}
7356	m.reserve(`256`);
7357
7358	let usable_cap = m.capacity();
7359	for i in `128`..(`128` + `256`) {
7360	m.insert(i, i);
7361	assert_eq!(m.capacity(), usable_cap);
7362	}
7363
7364	for i in `100`..(`128` + `256`) {
7365	assert_eq!(m.remove(&i), Some(i));
7366	}
7367	m.shrink_to_fit();
7368
7369	assert_eq!(m.len(), `100`);
7370	assert!(!m.is_empty());
7371	assert!(m.capacity() >= m.len());
7372
7373	for i in `0`..`100` {
7374	assert_eq!(m.remove(&i), Some(i));
7375	}
7376	m.shrink_to_fit();
7377	m.insert(`0`, `0`);
7378
7379	assert_eq!(m.len(), `1`);
7380	assert!(m.capacity() >= m.len());
7381	assert_eq!(m.remove(&`0`), Some(`0`));
7382	}
7383
7384	#[test]
7385	fn test_from_iter() {
7386	let xs = [(`1`, `1`), (`2`, `2`), (`2`, `2`), (`3`, `3`), (`4`, `4`), (`5`, `5`), (`6`, `6`)];
7387
7388	let map: HashMap<_, _> = xs.iter().copied().collect();
7389
7390	for &(k, v) in &xs {
7391	assert_eq!(map.get(&k), Some(&v));
7392	}
7393
7394	assert_eq!(map.iter().len(), xs.len() - `1`);
7395	}
7396
7397	#[test]
7398	fn test_size_hint() {
7399	let xs = [(`1`, `1`), (`2`, `2`), (`3`, `3`), (`4`, `4`), (`5`, `5`), (`6`, `6`)];
7400
7401	let map: HashMap<_, _> = xs.iter().copied().collect();
7402
7403	let mut iter = map.iter();
7404
7405	for _ in iter.by_ref().take(`3`) {}
7406
7407	assert_eq!(iter.size_hint(), (`3`, Some(`3`)));
7408	}
7409
7410	#[test]
7411	fn test_iter_len() {
7412	let xs = [(`1`, `1`), (`2`, `2`), (`3`, `3`), (`4`, `4`), (`5`, `5`), (`6`, `6`)];
7413
7414	let map: HashMap<_, _> = xs.iter().copied().collect();
7415
7416	let mut iter = map.iter();
7417
7418	for _ in iter.by_ref().take(`3`) {}
7419
7420	assert_eq!(iter.len(), `3`);
7421	}
7422
7423	#[test]
7424	fn test_mut_size_hint() {
7425	let xs = [(`1`, `1`), (`2`, `2`), (`3`, `3`), (`4`, `4`), (`5`, `5`), (`6`, `6`)];
7426
7427	let mut map: HashMap<_, _> = xs.iter().copied().collect();
7428
7429	let mut iter = map.iter_mut();
7430
7431	for _ in iter.by_ref().take(`3`) {}
7432
7433	assert_eq!(iter.size_hint(), (`3`, Some(`3`)));
7434	}
7435
7436	#[test]
7437	fn test_iter_mut_len() {
7438	let xs = [(`1`, `1`), (`2`, `2`), (`3`, `3`), (`4`, `4`), (`5`, `5`), (`6`, `6`)];
7439
7440	let mut map: HashMap<_, _> = xs.iter().copied().collect();
7441
7442	let mut iter = map.iter_mut();
7443
7444	for _ in iter.by_ref().take(`3`) {}
7445
7446	assert_eq!(iter.len(), `3`);
7447	}
7448
7449	#[test]
7450	fn test_index() {
7451	let mut map = HashMap::new();
7452
7453	map.insert(`1`, `2`);
7454	map.insert(`2`, `1`);
7455	map.insert(`3`, `4`);
7456
7457	assert_eq!(map[&`2`], `1`);
7458	}
7459
7460	#[test]
7461	#[should_panic]
7462	fn test_index_nonexistent() {
7463	let mut map = HashMap::new();
7464
7465	map.insert(`1`, `2`);
7466	map.insert(`2`, `1`);
7467	map.insert(`3`, `4`);
7468
7469	#[allow(clippy::no_effect)] // false positive lint
7470	map[&`4`];
7471	}
7472
7473	#[test]
7474	fn test_entry() {
7475	let xs = [(`1`, `10`), (`2`, `20`), (`3`, `30`), (`4`, `40`), (`5`, `50`), (`6`, `60`)];
7476
7477	let mut map: HashMap<_, _> = xs.iter().copied().collect();
7478
7479	// Existing key (insert)
7480	match map.entry(`1`) {
7481	Vacant(_) => unreachable!(),
7482	Occupied(mut view) => {
7483	assert_eq!(view.get(), &`10`);
7484	assert_eq!(view.insert(`100`), `10`);
7485	}
7486	}
7487	assert_eq!(map.get(&`1`).unwrap(), &`100`);
7488	assert_eq!(map.len(), `6`);
7489
7490	// Existing key (update)
7491	match map.entry(`2`) {
7492	Vacant(_) => unreachable!(),
7493	Occupied(mut view) => {
7494	let v = view.get_mut();
7495	let new_v = (v) `10`;
7496	*v = new_v;
7497	}
7498	}
7499	assert_eq!(map.get(&`2`).unwrap(), &`200`);
7500	assert_eq!(map.len(), `6`);
7501
7502	// Existing key (take)
7503	match map.entry(`3`) {
7504	Vacant(_) => unreachable!(),
7505	Occupied(view) => {
7506	assert_eq!(view.remove(), `30`);
7507	}
7508	}
7509	assert_eq!(map.get(&`3`), None);
7510	assert_eq!(map.len(), `5`);
7511
7512	// Inexistent key (insert)
7513	match map.entry(`10`) {
7514	Occupied(_) => unreachable!(),
7515	Vacant(view) => {
7516	assert_eq!(*view.insert(`1000`), `1000`);
7517	}
7518	}
7519	assert_eq!(map.get(&`10`).unwrap(), &`1000`);
7520	assert_eq!(map.len(), `6`);
7521	}
7522
7523	#[test]
7524	fn test_entry_ref() {
7525	let xs = [
7526	("One".to_owned(), `10`),
7527	("Two".to_owned(), `20`),
7528	("Three".to_owned(), `30`),
7529	("Four".to_owned(), `40`),
7530	("Five".to_owned(), `50`),
7531	("Six".to_owned(), `60`),
7532	];
7533
7534	let mut map: HashMap<_, _> = xs.iter().cloned().collect();
7535
7536	// Existing key (insert)
7537	match map.entry_ref("One") {
7538	EntryRef::Vacant(_) => unreachable!(),
7539	EntryRef::Occupied(mut view) => {
7540	assert_eq!(view.get(), &`10`);
7541	assert_eq!(view.insert(`100`), `10`);
7542	}
7543	}
7544	assert_eq!(map.get("One").unwrap(), &`100`);
7545	assert_eq!(map.len(), `6`);
7546
7547	// Existing key (update)
7548	match map.entry_ref("Two") {
7549	EntryRef::Vacant(_) => unreachable!(),
7550	EntryRef::Occupied(mut view) => {
7551	let v = view.get_mut();
7552	let new_v = (v) `10`;
7553	*v = new_v;
7554	}
7555	}
7556	assert_eq!(map.get("Two").unwrap(), &`200`);
7557	assert_eq!(map.len(), `6`);
7558
7559	// Existing key (take)
7560	match map.entry_ref("Three") {
7561	EntryRef::Vacant(_) => unreachable!(),
7562	EntryRef::Occupied(view) => {
7563	assert_eq!(view.remove(), `30`);
7564	}
7565	}
7566	assert_eq!(map.get("Three"), None);
7567	assert_eq!(map.len(), `5`);
7568
7569	// Inexistent key (insert)
7570	match map.entry_ref("Ten") {
7571	EntryRef::Occupied(_) => unreachable!(),
7572	EntryRef::Vacant(view) => {
7573	assert_eq!(*view.insert(`1000`), `1000`);
7574	}
7575	}
7576	assert_eq!(map.get("Ten").unwrap(), &`1000`);
7577	assert_eq!(map.len(), `6`);
7578	}
7579
7580	#[test]
7581	fn test_entry_take_doesnt_corrupt() {
7582	#![allow(deprecated)] //rand
7583	// Test for #19292
7584	fn check(m: &HashMap<i32, ()>) {
7585	for k in m.keys() {
7586	assert!(m.contains_key(k), "{k} is in keys() but not in the map?");
7587	}
7588	}
7589
7590	let mut m = HashMap::new();
7591
7592	let mut rng = {
7593	let seed = u64::from_le_bytes(*b"testseed");
7594	SmallRng::seed_from_u64(seed)
7595	};
7596
7597	// Populate the map with some items.
7598	for _ in `0`..`50` {
7599	let x = rng.gen_range(`-10`..`10`);
7600	m.insert(x, ());
7601	}
7602
7603	for _ in `0`..`1000` {
7604	let x = rng.gen_range(`-10`..`10`);
7605	match m.entry(x) {
7606	Vacant(_) => {}
7607	Occupied(e) => {
7608	e.remove();
7609	}
7610	}
7611
7612	check(&m);
7613	}
7614	}
7615
7616	#[test]
7617	fn test_entry_ref_take_doesnt_corrupt() {
7618	#![allow(deprecated)] //rand
7619	// Test for #19292
7620	fn check(m: &HashMap<std::string::String, ()>) {
7621	for k in m.keys() {
7622	assert!(m.contains_key(k), "{k} is in keys() but not in the map?");
7623	}
7624	}
7625
7626	let mut m = HashMap::new();
7627
7628	let mut rng = {
7629	let seed = u64::from_le_bytes(*b"testseed");
7630	SmallRng::seed_from_u64(seed)
7631	};
7632
7633	// Populate the map with some items.
7634	for _ in `0`..`50` {
7635	let mut x = std::string::String::with_capacity(`1`);
7636	x.push(rng.gen_range('a'..='z'));
7637	m.insert(x, ());
7638	}
7639
7640	for _ in `0`..`1000` {
7641	let mut x = std::string::String::with_capacity(`1`);
7642	x.push(rng.gen_range('a'..='z'));
7643	match m.entry_ref(x.as_str()) {
7644	EntryRef::Vacant(_) => {}
7645	EntryRef::Occupied(e) => {
7646	e.remove();
7647	}
7648	}
7649
7650	check(&m);
7651	}
7652	}
7653
7654	#[test]
7655	fn test_extend_ref_k_ref_v() {
7656	let mut a = HashMap::new();
7657	a.insert(`1`, "one");
7658	let mut b = HashMap::new();
7659	b.insert(`2`, "two");
7660	b.insert(`3`, "three");
7661
7662	a.extend(&b);
7663
7664	assert_eq!(a.len(), `3`);
7665	assert_eq!(a[&`1`], "one");
7666	assert_eq!(a[&`2`], "two");
7667	assert_eq!(a[&`3`], "three");
7668	}
7669
7670	#[test]
7671	#[allow(clippy::needless_borrow)]
7672	fn test_extend_ref_kv_tuple() {
7673	use std::ops::AddAssign;
7674	let mut a = HashMap::new();
7675	a.insert(`0`, `0`);
7676
7677	fn create_arr<T: AddAssign<T> + Copy, const N: usize>(start: T, step: T) -> [(T, T); N] {
7678	let mut outs: [(T, T); N] = [(start, start); N];
7679	let mut element = step;
7680	outs.iter_mut().skip(`1`).for_each(\|(k, v)\| {
7681	*k += element;
7682	*v += element;
7683	element += step;
7684	});
7685	outs
7686	}
7687
7688	let for_iter: Vec<_> = (`0`..`100`).map(\|i\| (i, i)).collect();
7689	let iter = for_iter.iter();
7690	let vec: Vec<_> = (`100`..`200`).map(\|i\| (i, i)).collect();
7691	a.extend(iter);
7692	a.extend(&vec);
7693	a.extend(create_arr::<i32, `100`>(`200`, `1`));
7694
7695	assert_eq!(a.len(), `300`);
7696
7697	for item in `0`..`300` {
7698	assert_eq!(a[&item], item);
7699	}
7700	}
7701
7702	#[test]
7703	fn test_capacity_not_less_than_len() {
7704	let mut a = HashMap::new();
7705	let mut item = `0`;
7706
7707	for _ in `0`..`116` {
7708	a.insert(item, `0`);
7709	item += `1`;
7710	}
7711
7712	assert!(a.capacity() > a.len());
7713
7714	let free = a.capacity() - a.len();
7715	for _ in `0`..free {
7716	a.insert(item, `0`);
7717	item += `1`;
7718	}
7719
7720	assert_eq!(a.len(), a.capacity());
7721
7722	// Insert at capacity should cause allocation.
7723	a.insert(item, `0`);
7724	assert!(a.capacity() > a.len());
7725	}
7726
7727	#[test]
7728	fn test_occupied_entry_key() {
7729	let mut a = HashMap::new();
7730	let key = "hello there";
7731	let value = "value goes here";
7732	assert!(a.is_empty());
7733	a.insert(key, value);
7734	assert_eq!(a.len(), `1`);
7735	assert_eq!(a[key], value);
7736
7737	match a.entry(key) {
7738	Vacant(_) => panic!(),
7739	Occupied(e) => assert_eq!(key, *e.key()),
7740	}
7741	assert_eq!(a.len(), `1`);
7742	assert_eq!(a[key], value);
7743	}
7744
7745	#[test]
7746	fn test_occupied_entry_ref_key() {
7747	let mut a = HashMap::new();
7748	let key = "hello there";
7749	let value = "value goes here";
7750	assert!(a.is_empty());
7751	a.insert(key.to_owned(), value);
7752	assert_eq!(a.len(), `1`);
7753	assert_eq!(a[key], value);
7754
7755	match a.entry_ref(key) {
7756	EntryRef::Vacant(_) => panic!(),
7757	EntryRef::Occupied(e) => assert_eq!(key, e.key()),
7758	}
7759	assert_eq!(a.len(), `1`);
7760	assert_eq!(a[key], value);
7761	}
7762
7763	#[test]
7764	fn test_vacant_entry_key() {
7765	let mut a = HashMap::new();
7766	let key = "hello there";
7767	let value = "value goes here";
7768
7769	assert!(a.is_empty());
7770	match a.entry(key) {
7771	Occupied(_) => panic!(),
7772	Vacant(e) => {
7773	assert_eq!(key, *e.key());
7774	e.insert(value);
7775	}
7776	}
7777	assert_eq!(a.len(), `1`);
7778	assert_eq!(a[key], value);
7779	}
7780
7781	#[test]
7782	fn test_vacant_entry_ref_key() {
7783	let mut a: HashMap<std::string::String, &str> = HashMap::new();
7784	let key = "hello there";
7785	let value = "value goes here";
7786
7787	assert!(a.is_empty());
7788	match a.entry_ref(key) {
7789	EntryRef::Occupied(_) => panic!(),
7790	EntryRef::Vacant(e) => {
7791	assert_eq!(key, e.key());
7792	e.insert(value);
7793	}
7794	}
7795	assert_eq!(a.len(), `1`);
7796	assert_eq!(a[key], value);
7797	}
7798
7799	#[test]
7800	fn test_occupied_entry_replace_entry_with() {
7801	let mut a = HashMap::new();
7802
7803	let key = "a key";
7804	let value = "an initial value";
7805	let new_value = "a new value";
7806
7807	let entry = a.entry(key).insert(value).replace_entry_with(\|k, v\| {
7808	assert_eq!(k, &key);
7809	assert_eq!(v, value);
7810	Some(new_value)
7811	});
7812
7813	match entry {
7814	Occupied(e) => {
7815	assert_eq!(e.key(), &key);
7816	assert_eq!(e.get(), &new_value);
7817	}
7818	Vacant(_) => panic!(),
7819	}
7820
7821	assert_eq!(a[key], new_value);
7822	assert_eq!(a.len(), `1`);
7823
7824	let entry = match a.entry(key) {
7825	Occupied(e) => e.replace_entry_with(\|k, v\| {
7826	assert_eq!(k, &key);
7827	assert_eq!(v, new_value);
7828	None
7829	}),
7830	Vacant(_) => panic!(),
7831	};
7832
7833	match entry {
7834	Vacant(e) => assert_eq!(e.key(), &key),
7835	Occupied(_) => panic!(),
7836	}
7837
7838	assert!(!a.contains_key(key));
7839	assert_eq!(a.len(), `0`);
7840	}
7841
7842	#[test]
7843	fn test_occupied_entry_ref_replace_entry_with() {
7844	let mut a: HashMap<std::string::String, &str> = HashMap::new();
7845
7846	let key = "a key";
7847	let value = "an initial value";
7848	let new_value = "a new value";
7849
7850	let entry = a.entry_ref(key).insert(value).replace_entry_with(\|k, v\| {
7851	assert_eq!(k, key);
7852	assert_eq!(v, value);
7853	Some(new_value)
7854	});
7855
7856	match entry {
7857	EntryRef::Occupied(e) => {
7858	assert_eq!(e.key(), key);
7859	assert_eq!(e.get(), &new_value);
7860	}
7861	EntryRef::Vacant(_) => panic!(),
7862	}
7863
7864	assert_eq!(a[key], new_value);
7865	assert_eq!(a.len(), `1`);
7866
7867	let entry = match a.entry_ref(key) {
7868	EntryRef::Occupied(e) => e.replace_entry_with(\|k, v\| {
7869	assert_eq!(k, key);
7870	assert_eq!(v, new_value);
7871	None
7872	}),
7873	EntryRef::Vacant(_) => panic!(),
7874	};
7875
7876	match entry {
7877	EntryRef::Vacant(e) => assert_eq!(e.key(), key),
7878	EntryRef::Occupied(_) => panic!(),
7879	}
7880
7881	assert!(!a.contains_key(key));
7882	assert_eq!(a.len(), `0`);
7883	}
7884
7885	#[test]
7886	fn test_entry_and_replace_entry_with() {
7887	let mut a = HashMap::new();
7888
7889	let key = "a key";
7890	let value = "an initial value";
7891	let new_value = "a new value";
7892
7893	let entry = a.entry(key).and_replace_entry_with(\|_, _\| panic!());
7894
7895	match entry {
7896	Vacant(e) => assert_eq!(e.key(), &key),
7897	Occupied(_) => panic!(),
7898	}
7899
7900	a.insert(key, value);
7901
7902	let entry = a.entry(key).and_replace_entry_with(\|k, v\| {
7903	assert_eq!(k, &key);
7904	assert_eq!(v, value);
7905	Some(new_value)
7906	});
7907
7908	match entry {
7909	Occupied(e) => {
7910	assert_eq!(e.key(), &key);
7911	assert_eq!(e.get(), &new_value);
7912	}
7913	Vacant(_) => panic!(),
7914	}
7915
7916	assert_eq!(a[key], new_value);
7917	assert_eq!(a.len(), `1`);
7918
7919	let entry = a.entry(key).and_replace_entry_with(\|k, v\| {
7920	assert_eq!(k, &key);
7921	assert_eq!(v, new_value);
7922	None
7923	});
7924
7925	match entry {
7926	Vacant(e) => assert_eq!(e.key(), &key),
7927	Occupied(_) => panic!(),
7928	}
7929
7930	assert!(!a.contains_key(key));
7931	assert_eq!(a.len(), `0`);
7932	}
7933
7934	#[test]
7935	fn test_entry_ref_and_replace_entry_with() {
7936	let mut a = HashMap::new();
7937
7938	let key = "a key";
7939	let value = "an initial value";
7940	let new_value = "a new value";
7941
7942	let entry = a.entry_ref(key).and_replace_entry_with(\|_, _\| panic!());
7943
7944	match entry {
7945	EntryRef::Vacant(e) => assert_eq!(e.key(), key),
7946	EntryRef::Occupied(_) => panic!(),
7947	}
7948
7949	a.insert(key.to_owned(), value);
7950
7951	let entry = a.entry_ref(key).and_replace_entry_with(\|k, v\| {
7952	assert_eq!(k, key);
7953	assert_eq!(v, value);
7954	Some(new_value)
7955	});
7956
7957	match entry {
7958	EntryRef::Occupied(e) => {
7959	assert_eq!(e.key(), key);
7960	assert_eq!(e.get(), &new_value);
7961	}
7962	EntryRef::Vacant(_) => panic!(),
7963	}
7964
7965	assert_eq!(a[key], new_value);
7966	assert_eq!(a.len(), `1`);
7967
7968	let entry = a.entry_ref(key).and_replace_entry_with(\|k, v\| {
7969	assert_eq!(k, key);
7970	assert_eq!(v, new_value);
7971	None
7972	});
7973
7974	match entry {
7975	EntryRef::Vacant(e) => assert_eq!(e.key(), key),
7976	EntryRef::Occupied(_) => panic!(),
7977	}
7978
7979	assert!(!a.contains_key(key));
7980	assert_eq!(a.len(), `0`);
7981	}
7982
7983	#[test]
7984	fn test_raw_occupied_entry_replace_entry_with() {
7985	let mut a = HashMap::new();
7986
7987	let key = "a key";
7988	let value = "an initial value";
7989	let new_value = "a new value";
7990
7991	let entry = a
7992	.raw_entry_mut()
7993	.from_key(&key)
7994	.insert(key, value)
7995	.replace_entry_with(\|k, v\| {
7996	assert_eq!(k, &key);
7997	assert_eq!(v, value);
7998	Some(new_value)
7999	});
8000
8001	match entry {
8002	RawEntryMut::Occupied(e) => {
8003	assert_eq!(e.key(), &key);
8004	assert_eq!(e.get(), &new_value);
8005	}
8006	RawEntryMut::Vacant(_) => panic!(),
8007	}
8008
8009	assert_eq!(a[key], new_value);
8010	assert_eq!(a.len(), `1`);
8011
8012	let entry = match a.raw_entry_mut().from_key(&key) {
8013	RawEntryMut::Occupied(e) => e.replace_entry_with(\|k, v\| {
8014	assert_eq!(k, &key);
8015	assert_eq!(v, new_value);
8016	None
8017	}),
8018	RawEntryMut::Vacant(_) => panic!(),
8019	};
8020
8021	match entry {
8022	RawEntryMut::Vacant(_) => {}
8023	RawEntryMut::Occupied(_) => panic!(),
8024	}
8025
8026	assert!(!a.contains_key(key));
8027	assert_eq!(a.len(), `0`);
8028	}
8029
8030	#[test]
8031	fn test_raw_entry_and_replace_entry_with() {
8032	let mut a = HashMap::new();
8033
8034	let key = "a key";
8035	let value = "an initial value";
8036	let new_value = "a new value";
8037
8038	let entry = a
8039	.raw_entry_mut()
8040	.from_key(&key)
8041	.and_replace_entry_with(\|_, _\| panic!());
8042
8043	match entry {
8044	RawEntryMut::Vacant(_) => {}
8045	RawEntryMut::Occupied(_) => panic!(),
8046	}
8047
8048	a.insert(key, value);
8049
8050	let entry = a
8051	.raw_entry_mut()
8052	.from_key(&key)
8053	.and_replace_entry_with(\|k, v\| {
8054	assert_eq!(k, &key);
8055	assert_eq!(v, value);
8056	Some(new_value)
8057	});
8058
8059	match entry {
8060	RawEntryMut::Occupied(e) => {
8061	assert_eq!(e.key(), &key);
8062	assert_eq!(e.get(), &new_value);
8063	}
8064	RawEntryMut::Vacant(_) => panic!(),
8065	}
8066
8067	assert_eq!(a[key], new_value);
8068	assert_eq!(a.len(), `1`);
8069
8070	let entry = a
8071	.raw_entry_mut()
8072	.from_key(&key)
8073	.and_replace_entry_with(\|k, v\| {
8074	assert_eq!(k, &key);
8075	assert_eq!(v, new_value);
8076	None
8077	});
8078
8079	match entry {
8080	RawEntryMut::Vacant(_) => {}
8081	RawEntryMut::Occupied(_) => panic!(),
8082	}
8083
8084	assert!(!a.contains_key(key));
8085	assert_eq!(a.len(), `0`);
8086	}
8087
8088	#[test]
8089	fn test_replace_entry_with_doesnt_corrupt() {
8090	#![allow(deprecated)] //rand
8091	// Test for #19292
8092	fn check(m: &HashMap<i32, ()>) {
8093	for k in m.keys() {
8094	assert!(m.contains_key(k), "{k} is in keys() but not in the map?");
8095	}
8096	}
8097
8098	let mut m = HashMap::new();
8099
8100	let mut rng = {
8101	let seed = u64::from_le_bytes(*b"testseed");
8102	SmallRng::seed_from_u64(seed)
8103	};
8104
8105	// Populate the map with some items.
8106	for _ in `0`..`50` {
8107	let x = rng.gen_range(`-10`..`10`);
8108	m.insert(x, ());
8109	}
8110
8111	for _ in `0`..`1000` {
8112	let x = rng.gen_range(`-10`..`10`);
8113	m.entry(x).and_replace_entry_with(\|_, _\| None);
8114	check(&m);
8115	}
8116	}
8117
8118	#[test]
8119	fn test_replace_entry_ref_with_doesnt_corrupt() {
8120	#![allow(deprecated)] //rand
8121	// Test for #19292
8122	fn check(m: &HashMap<std::string::String, ()>) {
8123	for k in m.keys() {
8124	assert!(m.contains_key(k), "{k} is in keys() but not in the map?");
8125	}
8126	}
8127
8128	let mut m = HashMap::new();
8129
8130	let mut rng = {
8131	let seed = u64::from_le_bytes(*b"testseed");
8132	SmallRng::seed_from_u64(seed)
8133	};
8134
8135	// Populate the map with some items.
8136	for _ in `0`..`50` {
8137	let mut x = std::string::String::with_capacity(`1`);
8138	x.push(rng.gen_range('a'..='z'));
8139	m.insert(x, ());
8140	}
8141
8142	for _ in `0`..`1000` {
8143	let mut x = std::string::String::with_capacity(`1`);
8144	x.push(rng.gen_range('a'..='z'));
8145	m.entry_ref(x.as_str()).and_replace_entry_with(\|_, _\| None);
8146	check(&m);
8147	}
8148	}
8149
8150	#[test]
8151	fn test_retain() {
8152	let mut map: HashMap<i32, i32> = (`0`..`100`).map(\|x\| (x, x * `10`)).collect();
8153
8154	map.retain(\|&k, _\| k % `2` == `0`);
8155	assert_eq!(map.len(), `50`);
8156	assert_eq!(map[&`2`], `20`);
8157	assert_eq!(map[&`4`], `40`);
8158	assert_eq!(map[&`6`], `60`);
8159	}
8160
8161	#[test]
8162	fn test_extract_if() {
8163	{
8164	let mut map: HashMap<i32, i32> = (`0`..`8`).map(\|x\| (x, x * `10`)).collect();
8165	let drained = map.extract_if(\|&k, _\| k % `2` == `0`);
8166	let mut out = drained.collect::<Vec<_>>();
8167	out.sort_unstable();
8168	assert_eq!(vec![(`0`, `0`), (`2`, `20`), (`4`, `40`), (`6`, `60`)], out);
8169	assert_eq!(map.len(), `4`);
8170	}
8171	{
8172	let mut map: HashMap<i32, i32> = (`0`..`8`).map(\|x\| (x, x * `10`)).collect();
8173	map.extract_if(\|&k, _\| k % `2` == `0`).for_each(drop);
8174	assert_eq!(map.len(), `4`);
8175	}
8176	}
8177
8178	#[test]
8179	#[cfg_attr(miri, ignore)] // FIXME: no OOM signalling (https://github.com/rust-lang/miri/issues/613)
8180	fn test_try_reserve() {
8181	use crate::TryReserveError::{AllocError, CapacityOverflow};
8182
8183	const MAX_ISIZE: usize = isize::MAX as usize;
8184
8185	let mut empty_bytes: HashMap<u8, u8> = HashMap::new();
8186
8187	if let Err(CapacityOverflow) = empty_bytes.try_reserve(usize::MAX) {
8188	} else {
8189	panic!("usize::MAX should trigger an overflow!");
8190	}
8191
8192	if let Err(CapacityOverflow) = empty_bytes.try_reserve(MAX_ISIZE) {
8193	} else {
8194	panic!("isize::MAX should trigger an overflow!");
8195	}
8196
8197	if let Err(AllocError { .. }) = empty_bytes.try_reserve(MAX_ISIZE / `5`) {
8198	} else {
8199	// This may succeed if there is enough free memory. Attempt to
8200	// allocate a few more hashmaps to ensure the allocation will fail.
8201	let mut empty_bytes2: HashMap<u8, u8> = HashMap::new();
8202	let _ = empty_bytes2.try_reserve(MAX_ISIZE / `5`);
8203	let mut empty_bytes3: HashMap<u8, u8> = HashMap::new();
8204	let _ = empty_bytes3.try_reserve(MAX_ISIZE / `5`);
8205	let mut empty_bytes4: HashMap<u8, u8> = HashMap::new();
8206	if let Err(AllocError { .. }) = empty_bytes4.try_reserve(MAX_ISIZE / `5`) {
8207	} else {
8208	panic!("isize::MAX / 5 should trigger an OOM!");
8209	}
8210	}
8211	}
8212
8213	#[test]
8214	fn test_raw_entry() {
8215	use super::RawEntryMut::{Occupied, Vacant};
8216
8217	let xs = [(`1_i32`, `10_i32`), (`2`, `20`), (`3`, `30`), (`4`, `40`), (`5`, `50`), (`6`, `60`)];
8218
8219	let mut map: HashMap<_, _> = xs.iter().copied().collect();
8220
8221	let compute_hash = \|map: &HashMap<i32, i32>, k: i32\| -> u64 {
8222	super::make_hash::<i32, _>(map.hasher(), &k)
8223	};
8224
8225	// Existing key (insert)
8226	match map.raw_entry_mut().from_key(&`1`) {
8227	Vacant(_) => unreachable!(),
8228	Occupied(mut view) => {
8229	assert_eq!(view.get(), &`10`);
8230	assert_eq!(view.insert(`100`), `10`);
8231	}
8232	}
8233	let hash1 = compute_hash(&map, `1`);
8234	assert_eq!(map.raw_entry().from_key(&`1`).unwrap(), (&`1`, &`100`));
8235	assert_eq!(
8236	map.raw_entry().from_hash(hash1, \|k\| *k == `1`).unwrap(),
8237	(&`1`, &`100`)
8238	);
8239	assert_eq!(
8240	map.raw_entry().from_key_hashed_nocheck(hash1, &`1`).unwrap(),
8241	(&`1`, &`100`)
8242	);
8243	assert_eq!(map.len(), `6`);
8244
8245	// Existing key (update)
8246	match map.raw_entry_mut().from_key(&`2`) {
8247	Vacant(_) => unreachable!(),
8248	Occupied(mut view) => {
8249	let v = view.get_mut();
8250	let new_v = (v) `10`;
8251	*v = new_v;
8252	}
8253	}
8254	let hash2 = compute_hash(&map, `2`);
8255	assert_eq!(map.raw_entry().from_key(&`2`).unwrap(), (&`2`, &`200`));
8256	assert_eq!(
8257	map.raw_entry().from_hash(hash2, \|k\| *k == `2`).unwrap(),
8258	(&`2`, &`200`)
8259	);
8260	assert_eq!(
8261	map.raw_entry().from_key_hashed_nocheck(hash2, &`2`).unwrap(),
8262	(&`2`, &`200`)
8263	);
8264	assert_eq!(map.len(), `6`);
8265
8266	// Existing key (take)
8267	let hash3 = compute_hash(&map, `3`);
8268	match map.raw_entry_mut().from_key_hashed_nocheck(hash3, &`3`) {
8269	Vacant(_) => unreachable!(),
8270	Occupied(view) => {
8271	assert_eq!(view.remove_entry(), (`3`, `30`));
8272	}
8273	}
8274	assert_eq!(map.raw_entry().from_key(&`3`), None);
8275	assert_eq!(map.raw_entry().from_hash(hash3, \|k\| *k == `3`), None);
8276	assert_eq!(map.raw_entry().from_key_hashed_nocheck(hash3, &`3`), None);
8277	assert_eq!(map.len(), `5`);
8278
8279	// Nonexistent key (insert)
8280	match map.raw_entry_mut().from_key(&`10`) {
8281	Occupied(_) => unreachable!(),
8282	Vacant(view) => {
8283	assert_eq!(view.insert(`10`, `1000`), (&mut `10`, &mut `1000`));
8284	}
8285	}
8286	assert_eq!(map.raw_entry().from_key(&`10`).unwrap(), (&`10`, &`1000`));
8287	assert_eq!(map.len(), `6`);
8288
8289	// Ensure all lookup methods produce equivalent results.
8290	for k in `0`..`12` {
8291	let hash = compute_hash(&map, k);
8292	let v = map.get(&k).copied();
8293	let kv = v.as_ref().map(\|v\| (&k, v));
8294
8295	assert_eq!(map.raw_entry().from_key(&k), kv);
8296	assert_eq!(map.raw_entry().from_hash(hash, \|q\| *q == k), kv);
8297	assert_eq!(map.raw_entry().from_key_hashed_nocheck(hash, &k), kv);
8298
8299	match map.raw_entry_mut().from_key(&k) {
8300	Occupied(o) => assert_eq!(Some(o.get_key_value()), kv),
8301	Vacant(_) => assert_eq!(v, None),
8302	}
8303	match map.raw_entry_mut().from_key_hashed_nocheck(hash, &k) {
8304	Occupied(o) => assert_eq!(Some(o.get_key_value()), kv),
8305	Vacant(_) => assert_eq!(v, None),
8306	}
8307	match map.raw_entry_mut().from_hash(hash, \|q\| *q == k) {
8308	Occupied(o) => assert_eq!(Some(o.get_key_value()), kv),
8309	Vacant(_) => assert_eq!(v, None),
8310	}
8311	}
8312	}
8313
8314	#[test]
8315	fn test_key_without_hash_impl() {
8316	#[derive(Debug)]
8317	struct IntWrapper(u64);
8318
8319	let mut m: HashMap<IntWrapper, (), ()> = HashMap::default();
8320	{
8321	assert!(m.raw_entry().from_hash(`0`, \|k\| k.`0` == `0`).is_none());
8322	}
8323	{
8324	let vacant_entry = match m.raw_entry_mut().from_hash(`0`, \|k\| k.0 == `0`) {
8325	RawEntryMut::Occupied(..) => panic!("Found entry for key 0"),
8326	RawEntryMut::Vacant(e) => e,
8327	};
8328	vacant_entry.insert_with_hasher(`0`, IntWrapper(`0`), (), \|k\| k.0);
8329	}
8330	{
8331	assert!(m.raw_entry().from_hash(`0`, \|k\| k.`0` == `0`).is_some());
8332	assert!(m.raw_entry().from_hash(`1`, \|k\| k.`0` == `1`).is_none());
8333	assert!(m.raw_entry().from_hash(`2`, \|k\| k.`0` == `2`).is_none());
8334	}
8335	{
8336	let vacant_entry = match m.raw_entry_mut().from_hash(`1`, \|k\| k.0 == `1`) {
8337	RawEntryMut::Occupied(..) => panic!("Found entry for key 1"),
8338	RawEntryMut::Vacant(e) => e,
8339	};
8340	vacant_entry.insert_with_hasher(`1`, IntWrapper(`1`), (), \|k\| k.0);
8341	}
8342	{
8343	assert!(m.raw_entry().from_hash(`0`, \|k\| k.`0` == `0`).is_some());
8344	assert!(m.raw_entry().from_hash(`1`, \|k\| k.`0` == `1`).is_some());
8345	assert!(m.raw_entry().from_hash(`2`, \|k\| k.`0` == `2`).is_none());
8346	}
8347	{
8348	let occupied_entry = match m.raw_entry_mut().from_hash(`0`, \|k\| k.0 == `0`) {
8349	RawEntryMut::Occupied(e) => e,
8350	RawEntryMut::Vacant(..) => panic!("Couldn't find entry for key 0"),
8351	};
8352	occupied_entry.remove();
8353	}
8354	assert!(m.raw_entry().from_hash(`0`, \|k\| k.`0` == `0`).is_none());
8355	assert!(m.raw_entry().from_hash(`1`, \|k\| k.`0` == `1`).is_some());
8356	assert!(m.raw_entry().from_hash(`2`, \|k\| k.`0` == `2`).is_none());
8357	}
8358
8359	#[test]
8360	#[cfg(feature = "raw")]
8361	fn test_into_iter_refresh() {
8362	#[cfg(miri)]
8363	const N: usize = `32`;
8364	#[cfg(not(miri))]
8365	const N: usize = `128`;
8366
8367	let mut rng = rand::thread_rng();
8368	for n in `0`..N {
8369	let mut map = HashMap::new();
8370	for i in `0`..n {
8371	assert!(map.insert(i, `2` * i).is_none());
8372	}
8373	let hash_builder = map.hasher().clone();
8374
8375	let mut it = unsafe { map.table.iter() };
8376	assert_eq!(it.len(), n);
8377
8378	let mut i = `0`;
8379	let mut left = n;
8380	let mut removed = Vec::new();
8381	loop {
8382	// occasionally remove some elements
8383	if i < n && rng.gen_bool(`0.1`) {
8384	let hash_value = super::make_hash(&hash_builder, &i);
8385
8386	unsafe {
8387	let e = map.table.find(hash_value, \|q\| q.0.eq(&i));
8388	if let Some(e) = e {
8389	it.reflect_remove(&e);
8390	let t = map.table.remove(e).0;
8391	removed.push(t);
8392	left -= `1`;
8393	} else {
8394	assert!(removed.contains(&(i, `2` * i)), "{i} not in {removed:?}");
8395	let e = map.table.insert(
8396	hash_value,
8397	(i, `2` * i),
8398	super::make_hasher::<_, usize, _>(&hash_builder),
8399	);
8400	it.reflect_insert(&e);
8401	if let Some(p) = removed.iter().position(\|e\| e == &(i, `2` * i)) {
8402	removed.swap_remove(p);
8403	}
8404	left += `1`;
8405	}
8406	}
8407	}
8408
8409	let e = it.next();
8410	if e.is_none() {
8411	break;
8412	}
8413	assert!(i < n);
8414	let t = unsafe { e.unwrap().as_ref() };
8415	assert!(!removed.contains(t));
8416	let (key, value) = t;
8417	assert_eq!(value, `2` key);
8418	i += `1`;
8419	}
8420	assert!(i <= n);
8421
8422	// just for safety:
8423	assert_eq!(map.table.len(), left);
8424	}
8425	}
8426
8427	#[test]
8428	fn test_const_with_hasher() {
8429	use core::hash::BuildHasher;
8430	use std::collections::hash_map::DefaultHasher;
8431
8432	#[derive(Clone)]
8433	struct MyHasher;
8434	impl BuildHasher for MyHasher {
8435	type Hasher = DefaultHasher;
8436
8437	fn build_hasher(&self) -> DefaultHasher {
8438	DefaultHasher::new()
8439	}
8440	}
8441
8442	const EMPTY_MAP: HashMap<u32, std::string::String, MyHasher> =
8443	HashMap::with_hasher(MyHasher);
8444
8445	let mut map = EMPTY_MAP;
8446	map.insert(`17`, "seventeen".to_owned());
8447	assert_eq!("seventeen", map[&`17`]);
8448	}
8449
8450	#[test]
8451	fn test_get_each_mut() {
8452	let mut map = HashMap::new();
8453	map.insert("foo".to_owned(), `0`);
8454	map.insert("bar".to_owned(), `10`);
8455	map.insert("baz".to_owned(), `20`);
8456	map.insert("qux".to_owned(), `30`);
8457
8458	let xs = map.get_many_mut(["foo", "qux"]);
8459	assert_eq!(xs, Some([&mut `0`, &mut `30`]));
8460
8461	let xs = map.get_many_mut(["foo", "dud"]);
8462	assert_eq!(xs, None);
8463
8464	let xs = map.get_many_mut(["foo", "foo"]);
8465	assert_eq!(xs, None);
8466
8467	let ys = map.get_many_key_value_mut(["bar", "baz"]);
8468	assert_eq!(
8469	ys,
8470	Some([(&"bar".to_owned(), &mut `10`), (&"baz".to_owned(), &mut `20`),]),
8471	);
8472
8473	let ys = map.get_many_key_value_mut(["bar", "dip"]);
8474	assert_eq!(ys, None);
8475
8476	let ys = map.get_many_key_value_mut(["baz", "baz"]);
8477	assert_eq!(ys, None);
8478	}
8479
8480	#[test]
8481	#[should_panic = "panic in drop"]
8482	fn test_clone_from_double_drop() {
8483	#[derive(Clone)]
8484	struct CheckedDrop {
8485	panic_in_drop: bool,
8486	dropped: bool,
8487	}
8488	impl Drop for CheckedDrop {
8489	fn drop(&mut self) {
8490	if self.panic_in_drop {
8491	self.dropped = `true`;
8492	panic!("panic in drop");
8493	}
8494	if self.dropped {
8495	panic!("double drop");
8496	}
8497	self.dropped = `true`;
8498	}
8499	}
8500	const DISARMED: CheckedDrop = CheckedDrop {
8501	panic_in_drop: `false`,
8502	dropped: `false`,
8503	};
8504	const ARMED: CheckedDrop = CheckedDrop {
8505	panic_in_drop: `true`,
8506	dropped: `false`,
8507	};
8508
8509	let mut map1 = HashMap::new();
8510	map1.insert(`1`, DISARMED);
8511	map1.insert(`2`, DISARMED);
8512	map1.insert(`3`, DISARMED);
8513	map1.insert(`4`, DISARMED);
8514
8515	let mut map2 = HashMap::new();
8516	map2.insert(`1`, DISARMED);
8517	map2.insert(`2`, ARMED);
8518	map2.insert(`3`, DISARMED);
8519	map2.insert(`4`, DISARMED);
8520
8521	map2.clone_from(&map1);
8522	}
8523
8524	#[test]
8525	#[should_panic = "panic in clone"]
8526	fn test_clone_from_memory_leaks() {
8527	use alloc::vec::Vec;
8528
8529	struct CheckedClone {
8530	panic_in_clone: bool,
8531	need_drop: Vec<i32>,
8532	}
8533	impl Clone for CheckedClone {
8534	fn clone(&self) -> Self {
8535	if self.panic_in_clone {
8536	panic!("panic in clone")
8537	}
8538	Self {
8539	panic_in_clone: self.panic_in_clone,
8540	need_drop: self.need_drop.clone(),
8541	}
8542	}
8543	}
8544	let mut map1 = HashMap::new();
8545	map1.insert(
8546	`1`,
8547	CheckedClone {
8548	panic_in_clone: `false`,
8549	need_drop: vec![`0`, `1`, `2`],
8550	},
8551	);
8552	map1.insert(
8553	`2`,
8554	CheckedClone {
8555	panic_in_clone: `false`,
8556	need_drop: vec![`3`, `4`, `5`],
8557	},
8558	);
8559	map1.insert(
8560	`3`,
8561	CheckedClone {
8562	panic_in_clone: `true`,
8563	need_drop: vec![`6`, `7`, `8`],
8564	},
8565	);
8566	let _map2 = map1.clone();
8567	}
8568
8569	struct MyAllocInner {
8570	drop_count: Arc<AtomicI8>,
8571	}
8572
8573	#[derive(Clone)]
8574	struct MyAlloc {
8575	_inner: Arc<MyAllocInner>,
8576	}
8577
8578	impl MyAlloc {
8579	fn new(drop_count: Arc<AtomicI8>) -> Self {
8580	MyAlloc {
8581	_inner: Arc::new(MyAllocInner { drop_count }),
8582	}
8583	}
8584	}
8585
8586	impl Drop for MyAllocInner {
8587	fn drop(&mut self) {
8588	println!("MyAlloc freed.");
8589	self.drop_count.fetch_sub(`1`, Ordering::SeqCst);
8590	}
8591	}
8592
8593	unsafe impl Allocator for MyAlloc {
8594	fn allocate(&self, layout: Layout) -> std::result::Result<NonNull<[u8]>, AllocError> {
8595	let g = Global;
8596	g.allocate(layout)
8597	}
8598
8599	unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout) {
8600	let g = Global;
8601	g.deallocate(ptr, layout)
8602	}
8603	}
8604
8605	#[test]
8606	fn test_hashmap_into_iter_bug() {
8607	let dropped: Arc<AtomicI8> = Arc::new(AtomicI8::new(`1`));
8608
8609	{
8610	let mut map = HashMap::with_capacity_in(`10`, MyAlloc::new(dropped.clone()));
8611	for i in `0`..`10` {
8612	map.entry(i).or_insert_with(\|\| "i".to_string());
8613	}
8614
8615	for (k, v) in map {
8616	println!("{}, {}", k, v);
8617	}
8618	}
8619
8620	// All allocator clones should already be dropped.
8621	assert_eq!(dropped.load(Ordering::SeqCst), `0`);
8622	}
8623
8624	#[derive(Debug)]
8625	struct CheckedCloneDrop<T> {
8626	panic_in_clone: bool,
8627	panic_in_drop: bool,
8628	dropped: bool,
8629	data: T,
8630	}
8631
8632	impl<T> CheckedCloneDrop<T> {
8633	fn new(panic_in_clone: bool, panic_in_drop: bool, data: T) -> Self {
8634	CheckedCloneDrop {
8635	panic_in_clone,
8636	panic_in_drop,
8637	dropped: `false`,
8638	data,
8639	}
8640	}
8641	}
8642
8643	impl<T: Clone> Clone for CheckedCloneDrop<T> {
8644	fn clone(&self) -> Self {
8645	if self.panic_in_clone {
8646	panic!("panic in clone")
8647	}
8648	Self {
8649	panic_in_clone: self.panic_in_clone,
8650	panic_in_drop: self.panic_in_drop,
8651	dropped: self.dropped,
8652	data: self.data.clone(),
8653	}
8654	}
8655	}
8656
8657	impl<T> Drop for CheckedCloneDrop<T> {
8658	fn drop(&mut self) {
8659	if self.panic_in_drop {
8660	self.dropped = `true`;
8661	panic!("panic in drop");
8662	}
8663	if self.dropped {
8664	panic!("double drop");
8665	}
8666	self.dropped = `true`;
8667	}
8668	}
8669
8670	/// Return hashmap with predefined distribution of elements.
8671	/// All elements will be located in the same order as elements
8672	/// returned by iterator.
8673	///
8674	/// This function does not panic, but returns an error as a `String`
8675	/// to distinguish between a test panic and an error in the input data.
8676	fn get_test_map<I, T, A>(
8677	iter: I,
8678	mut fun: impl FnMut(u64) -> T,
8679	alloc: A,
8680	) -> Result<HashMap<u64, CheckedCloneDrop<T>, DefaultHashBuilder, A>, String>
8681	where
8682	I: Iterator<Item = (bool, bool)> + Clone + ExactSizeIterator,
8683	A: Allocator,
8684	T: PartialEq + core::fmt::Debug,
8685	{
8686	use crate::scopeguard::guard;
8687
8688	let mut map: HashMap<u64, CheckedCloneDrop<T>, _, A> =
8689	HashMap::with_capacity_in(iter.size_hint().0, alloc);
8690	{
8691	let mut guard = guard(&mut map, \|map\| {
8692	for (_, value) in map.iter_mut() {
8693	value.panic_in_drop = `false`
8694	}
8695	});
8696
8697	let mut count = `0`;
8698	// Hash and Key must be equal to each other for controlling the elements placement.
8699	for (panic_in_clone, panic_in_drop) in iter.clone() {
8700	if core::mem::needs_drop::<T>() && panic_in_drop {
8701	return Err(String::from(
8702	"panic_in_drop can be set with a type that doesn't need to be dropped",
8703	));
8704	}
8705	guard.table.insert(
8706	count,
8707	(
8708	count,
8709	CheckedCloneDrop::new(panic_in_clone, panic_in_drop, fun(count)),
8710	),
8711	\|(k, _)\| *k,
8712	);
8713	count += `1`;
8714	}
8715
8716	// Let's check that all elements are located as we wanted
8717	let mut check_count = `0`;
8718	for ((key, value), (panic_in_clone, panic_in_drop)) in guard.iter().zip(iter) {
8719	if *key != check_count {
8720	return Err(format!(
8721	"key != check_count,`\n`key: `{}`,`\n`check_count: `{}`",
8722	key, check_count
8723	));
8724	}
8725	if value.dropped
8726	\|\| value.panic_in_clone != panic_in_clone
8727	\|\| value.panic_in_drop != panic_in_drop
8728	\|\| value.data != fun(check_count)
8729	{
8730	return Err(format!(
8731	"Value is not equal to expected,`\n`value: `{:?}`,`\n`expected: \
8732	`CheckedCloneDrop {{ panic_in_clone: {}, panic_in_drop: {}, dropped: {}, data: {:?} }}`",
8733	value, panic_in_clone, panic_in_drop, `false`, fun(check_count)
8734	));
8735	}
8736	check_count += `1`;
8737	}
8738
8739	if guard.len() != check_count as usize {
8740	return Err(format!(
8741	"map.len() != check_count,`\n`map.len(): `{}`,`\n`check_count: `{}`",
8742	guard.len(),
8743	check_count
8744	));
8745	}
8746
8747	if count != check_count {
8748	return Err(format!(
8749	"count != check_count,`\n`count: `{}`,`\n`check_count: `{}`",
8750	count, check_count
8751	));
8752	}
8753	core::mem::forget(guard);
8754	}
8755	Ok(map)
8756	}
8757
8758	const DISARMED: bool = `false`;
8759	const ARMED: bool = `true`;
8760
8761	const ARMED_FLAGS: [bool; `8`] = [
8762	DISARMED, DISARMED, DISARMED, ARMED, DISARMED, DISARMED, DISARMED, DISARMED,
8763	];
8764
8765	const DISARMED_FLAGS: [bool; `8`] = [
8766	DISARMED, DISARMED, DISARMED, DISARMED, DISARMED, DISARMED, DISARMED, DISARMED,
8767	];
8768
8769	#[test]
8770	#[should_panic = "panic in clone"]
8771	fn test_clone_memory_leaks_and_double_drop_one() {
8772	let dropped: Arc<AtomicI8> = Arc::new(AtomicI8::new(`2`));
8773
8774	{
8775	assert_eq!(ARMED_FLAGS.len(), DISARMED_FLAGS.len());
8776
8777	let map: HashMap<u64, CheckedCloneDrop<Vec<u64>>, DefaultHashBuilder, MyAlloc> =
8778	match get_test_map(
8779	ARMED_FLAGS.into_iter().zip(DISARMED_FLAGS),
8780	\|n\| vec![n],
8781	MyAlloc::new(dropped.clone()),
8782	) {
8783	Ok(map) => map,
8784	Err(msg) => panic!("{msg}"),
8785	};
8786
8787	// Clone should normally clone a few elements, and then (when the
8788	// clone function panics), deallocate both its own memory, memory
8789	// of `dropped: Arc<AtomicI8>` and the memory of already cloned
8790	// elements (Vec<i32> memory inside CheckedCloneDrop).
8791	let _map2 = map.clone();
8792	}
8793	}
8794
8795	#[test]
8796	#[should_panic = "panic in drop"]
8797	fn test_clone_memory_leaks_and_double_drop_two() {
8798	let dropped: Arc<AtomicI8> = Arc::new(AtomicI8::new(`2`));
8799
8800	{
8801	assert_eq!(ARMED_FLAGS.len(), DISARMED_FLAGS.len());
8802
8803	let map: HashMap<u64, CheckedCloneDrop<u64>, DefaultHashBuilder, _> = match get_test_map(
8804	DISARMED_FLAGS.into_iter().zip(DISARMED_FLAGS),
8805	\|n\| n,
8806	MyAlloc::new(dropped.clone()),
8807	) {
8808	Ok(map) => map,
8809	Err(msg) => panic!("{msg}"),
8810	};
8811
8812	let mut map2 = match get_test_map(
8813	DISARMED_FLAGS.into_iter().zip(ARMED_FLAGS),
8814	\|n\| n,
8815	MyAlloc::new(dropped.clone()),
8816	) {
8817	Ok(map) => map,
8818	Err(msg) => panic!("{msg}"),
8819	};
8820
8821	// The `clone_from` should try to drop the elements of `map2` without
8822	// double drop and leaking the allocator. Elements that have not been
8823	// dropped leak their memory.
8824	map2.clone_from(&map);
8825	}
8826	}
8827
8828	/// We check that we have a working table if the clone operation from another
8829	/// thread ended in a panic (when buckets of maps are equal to each other).
8830	#[test]
8831	fn test_catch_panic_clone_from_when_len_is_equal() {
8832	use std::thread;
8833
8834	let dropped: Arc<AtomicI8> = Arc::new(AtomicI8::new(`2`));
8835
8836	{
8837	assert_eq!(ARMED_FLAGS.len(), DISARMED_FLAGS.len());
8838
8839	let mut map = match get_test_map(
8840	DISARMED_FLAGS.into_iter().zip(DISARMED_FLAGS),
8841	\|n\| vec![n],
8842	MyAlloc::new(dropped.clone()),
8843	) {
8844	Ok(map) => map,
8845	Err(msg) => panic!("{msg}"),
8846	};
8847
8848	thread::scope(\|s\| {
8849	let result: thread::ScopedJoinHandle<'_, String> = s.spawn(\|\| {
8850	let scope_map =
8851	match get_test_map(ARMED_FLAGS.into_iter().zip(DISARMED_FLAGS), \|n\| vec![n * `2`], MyAlloc::new(dropped.clone())) {
8852	Ok(map) => map,
8853	Err(msg) => return msg,
8854	};
8855	if map.table.buckets() != scope_map.table.buckets() {
8856	return format!(
8857	"map.table.buckets() != scope_map.table.buckets(),`\n`left: `{}`,`\n`right: `{}`",
8858	map.table.buckets(), scope_map.table.buckets()
8859	);
8860	}
8861	map.clone_from(&scope_map);
8862	"We must fail the cloning!!!".to_owned()
8863	});
8864	if let Ok(msg) = result.join() {
8865	panic!("{msg}")
8866	}
8867	});
8868
8869	// Let's check that all iterators work fine and do not return elements
8870	// (especially `RawIterRange`, which does not depend on the number of
8871	// elements in the table, but looks directly at the control bytes)
8872	//
8873	// SAFETY: We know for sure that `RawTable` will outlive
8874	// the returned `RawIter / RawIterRange` iterator.
8875	assert_eq!(map.len(), `0`);
8876	assert_eq!(map.iter().count(), `0`);
8877	assert_eq!(unsafe { map.table.iter().count() }, `0`);
8878	assert_eq!(unsafe { map.table.iter().iter.count() }, `0`);
8879
8880	for idx in `0`..map.table.buckets() {
8881	let idx = idx as u64;
8882	assert!(
8883	map.table.find(idx, \|(k, _)\| *k == idx).is_none(),
8884	"Index: {idx}"
8885	);
8886	}
8887	}
8888
8889	// All allocator clones should already be dropped.
8890	assert_eq!(dropped.load(Ordering::SeqCst), `0`);
8891	}
8892
8893	/// We check that we have a working table if the clone operation from another
8894	/// thread ended in a panic (when buckets of maps are not equal to each other).
8895	#[test]
8896	fn test_catch_panic_clone_from_when_len_is_not_equal() {
8897	use std::thread;
8898
8899	let dropped: Arc<AtomicI8> = Arc::new(AtomicI8::new(`2`));
8900
8901	{
8902	assert_eq!(ARMED_FLAGS.len(), DISARMED_FLAGS.len());
8903
8904	let mut map = match get_test_map(
8905	[DISARMED].into_iter().zip([DISARMED]),
8906	\|n\| vec![n],
8907	MyAlloc::new(dropped.clone()),
8908	) {
8909	Ok(map) => map,
8910	Err(msg) => panic!("{msg}"),
8911	};
8912
8913	thread::scope(\|s\| {
8914	let result: thread::ScopedJoinHandle<'_, String> = s.spawn(\|\| {
8915	let scope_map = match get_test_map(
8916	ARMED_FLAGS.into_iter().zip(DISARMED_FLAGS),
8917	\|n\| vec![n * `2`],
8918	MyAlloc::new(dropped.clone()),
8919	) {
8920	Ok(map) => map,
8921	Err(msg) => return msg,
8922	};
8923	if map.table.buckets() == scope_map.table.buckets() {
8924	return format!(
8925	"map.table.buckets() == scope_map.table.buckets(): `{}`",
8926	map.table.buckets()
8927	);
8928	}
8929	map.clone_from(&scope_map);
8930	"We must fail the cloning!!!".to_owned()
8931	});
8932	if let Ok(msg) = result.join() {
8933	panic!("{msg}")
8934	}
8935	});
8936
8937	// Let's check that all iterators work fine and do not return elements
8938	// (especially `RawIterRange`, which does not depend on the number of
8939	// elements in the table, but looks directly at the control bytes)
8940	//
8941	// SAFETY: We know for sure that `RawTable` will outlive
8942	// the returned `RawIter / RawIterRange` iterator.
8943	assert_eq!(map.len(), `0`);
8944	assert_eq!(map.iter().count(), `0`);
8945	assert_eq!(unsafe { map.table.iter().count() }, `0`);
8946	assert_eq!(unsafe { map.table.iter().iter.count() }, `0`);
8947
8948	for idx in `0`..map.table.buckets() {
8949	let idx = idx as u64;
8950	assert!(
8951	map.table.find(idx, \|(k, _)\| *k == idx).is_none(),
8952	"Index: {idx}"
8953	);
8954	}
8955	}
8956
8957	// All allocator clones should already be dropped.
8958	assert_eq!(dropped.load(Ordering::SeqCst), `0`);
8959	}
8960	}
8961