1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
use self::RustcEntry::*;
use crate::map::{make_hash, Drain, HashMap, IntoIter, Iter, IterMut};
use crate::raw::{Allocator, Bucket, Global, RawTable};
use core::fmt::{self, Debug};
use core::hash::{BuildHasher, Hash};
use core::mem;

impl<K, V, S, A> HashMap<K, V, S, A>
where
    K: Eq + Hash,
    S: BuildHasher,
    A: Allocator + Clone,
{
    /// Gets the given key's corresponding entry in the map for in-place manipulation.
    ///
    /// # Examples
    ///
    /// ```
    /// use hashbrown::HashMap;
    ///
    /// let mut letters = HashMap::new();
    ///
    /// for ch in "a short treatise on fungi".chars() {
    ///     let counter = letters.rustc_entry(ch).or_insert(0);
    ///     *counter += 1;
    /// }
    ///
    /// assert_eq!(letters[&'s'], 2);
    /// assert_eq!(letters[&'t'], 3);
    /// assert_eq!(letters[&'u'], 1);
    /// assert_eq!(letters.get(&'y'), None);
    /// ```
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn rustc_entry(&mut self, key: K) -> RustcEntry<'_, K, V, A> {
        let hash = make_hash(&self.hash_builder, &key);
        if let Some(elem) = self.table.find(hash, |q| q.0.eq(&key)) {
            RustcEntry::Occupied(RustcOccupiedEntry {
                key: Some(key),
                elem,
                table: &mut self.table,
            })
        } else {
            // Ideally we would put this in VacantEntry::insert, but Entry is not
            // generic over the BuildHasher and adding a generic parameter would be
            // a breaking change.
            self.reserve(1);

            RustcEntry::Vacant(RustcVacantEntry {
                hash,
                key,
                table: &mut self.table,
            })
        }
    }
}

/// A view into a single entry in a map, which may either be vacant or occupied.
///
/// This `enum` is constructed from the [`rustc_entry`] method on [`HashMap`].
///
/// [`HashMap`]: struct.HashMap.html
/// [`rustc_entry`]: struct.HashMap.html#method.rustc_entry
pub enum RustcEntry<'a, K, V, A = Global>
where
    A: Allocator + Clone,
{
    /// An occupied entry.
    Occupied(RustcOccupiedEntry<'a, K, V, A>),

    /// A vacant entry.
    Vacant(RustcVacantEntry<'a, K, V, A>),
}

impl<K: Debug, V: Debug, A: Allocator + Clone> Debug for RustcEntry<'_, K, V, A> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match *self {
            Vacant(ref v) => f.debug_tuple("Entry").field(v).finish(),
            Occupied(ref o) => f.debug_tuple("Entry").field(o).finish(),
        }
    }
}

/// A view into an occupied entry in a `HashMap`.
/// It is part of the [`RustcEntry`] enum.
///
/// [`RustcEntry`]: enum.RustcEntry.html
pub struct RustcOccupiedEntry<'a, K, V, A = Global>
where
    A: Allocator + Clone,
{
    key: Option<K>,
    elem: Bucket<(K, V)>,
    table: &'a mut RawTable<(K, V), A>,
}

unsafe impl<K, V, A> Send for RustcOccupiedEntry<'_, K, V, A>
where
    K: Send,
    V: Send,
    A: Allocator + Clone + Send,
{
}
unsafe impl<K, V, A> Sync for RustcOccupiedEntry<'_, K, V, A>
where
    K: Sync,
    V: Sync,
    A: Allocator + Clone + Sync,
{
}

impl<K: Debug, V: Debug, A: Allocator + Clone> Debug for RustcOccupiedEntry<'_, K, V, A> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("OccupiedEntry")
            .field("key", self.key())
            .field("value", self.get())
            .finish()
    }
}

/// A view into a vacant entry in a `HashMap`.
/// It is part of the [`RustcEntry`] enum.
///
/// [`RustcEntry`]: enum.RustcEntry.html
pub struct RustcVacantEntry<'a, K, V, A = Global>
where
    A: Allocator + Clone,
{
    hash: u64,
    key: K,
    table: &'a mut RawTable<(K, V), A>,
}

impl<K: Debug, V, A: Allocator + Clone> Debug for RustcVacantEntry<'_, K, V, A> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_tuple("VacantEntry").field(self.key()).finish()
    }
}

impl<'a, K, V, A: Allocator + Clone> RustcEntry<'a, K, V, A> {
    /// Sets the value of the entry, and returns a RustcOccupiedEntry.
    ///
    /// # Examples
    ///
    /// ```
    /// use hashbrown::HashMap;
    ///
    /// let mut map: HashMap<&str, u32> = HashMap::new();
    /// let entry = map.rustc_entry("horseyland").insert(37);
    ///
    /// assert_eq!(entry.key(), &"horseyland");
    /// ```
    pub fn insert(self, value: V) -> RustcOccupiedEntry<'a, K, V, A> {
        match self {
            Vacant(entry) => entry.insert_entry(value),
            Occupied(mut entry) => {
                entry.insert(value);
                entry
            }
        }
    }

    /// Ensures a value is in the entry by inserting the default if empty, and returns
    /// a mutable reference to the value in the entry.
    ///
    /// # Examples
    ///
    /// ```
    /// use hashbrown::HashMap;
    ///
    /// let mut map: HashMap<&str, u32> = HashMap::new();
    ///
    /// map.rustc_entry("poneyland").or_insert(3);
    /// assert_eq!(map["poneyland"], 3);
    ///
    /// *map.rustc_entry("poneyland").or_insert(10) *= 2;
    /// assert_eq!(map["poneyland"], 6);
    /// ```
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn or_insert(self, default: V) -> &'a mut V
    where
        K: Hash,
    {
        match self {
            Occupied(entry) => entry.into_mut(),
            Vacant(entry) => entry.insert(default),
        }
    }

    /// Ensures a value is in the entry by inserting the result of the default function if empty,
    /// and returns a mutable reference to the value in the entry.
    ///
    /// # Examples
    ///
    /// ```
    /// use hashbrown::HashMap;
    ///
    /// let mut map: HashMap<&str, String> = HashMap::new();
    /// let s = "hoho".to_string();
    ///
    /// map.rustc_entry("poneyland").or_insert_with(|| s);
    ///
    /// assert_eq!(map["poneyland"], "hoho".to_string());
    /// ```
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn or_insert_with<F: FnOnce() -> V>(self, default: F) -> &'a mut V
    where
        K: Hash,
    {
        match self {
            Occupied(entry) => entry.into_mut(),
            Vacant(entry) => entry.insert(default()),
        }
    }

    /// Returns a reference to this entry's key.
    ///
    /// # Examples
    ///
    /// ```
    /// use hashbrown::HashMap;
    ///
    /// let mut map: HashMap<&str, u32> = HashMap::new();
    /// assert_eq!(map.rustc_entry("poneyland").key(), &"poneyland");
    /// ```
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn key(&self) -> &K {
        match *self {
            Occupied(ref entry) => entry.key(),
            Vacant(ref entry) => entry.key(),
        }
    }

    /// Provides in-place mutable access to an occupied entry before any
    /// potential inserts into the map.
    ///
    /// # Examples
    ///
    /// ```
    /// use hashbrown::HashMap;
    ///
    /// let mut map: HashMap<&str, u32> = HashMap::new();
    ///
    /// map.rustc_entry("poneyland")
    ///    .and_modify(|e| { *e += 1 })
    ///    .or_insert(42);
    /// assert_eq!(map["poneyland"], 42);
    ///
    /// map.rustc_entry("poneyland")
    ///    .and_modify(|e| { *e += 1 })
    ///    .or_insert(42);
    /// assert_eq!(map["poneyland"], 43);
    /// ```
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn and_modify<F>(self, f: F) -> Self
    where
        F: FnOnce(&mut V),
    {
        match self {
            Occupied(mut entry) => {
                f(entry.get_mut());
                Occupied(entry)
            }
            Vacant(entry) => Vacant(entry),
        }
    }
}

impl<'a, K, V: Default, A: Allocator + Clone> RustcEntry<'a, K, V, A> {
    /// Ensures a value is in the entry by inserting the default value if empty,
    /// and returns a mutable reference to the value in the entry.
    ///
    /// # Examples
    ///
    /// ```
    /// # fn main() {
    /// use hashbrown::HashMap;
    ///
    /// let mut map: HashMap<&str, Option<u32>> = HashMap::new();
    /// map.rustc_entry("poneyland").or_default();
    ///
    /// assert_eq!(map["poneyland"], None);
    /// # }
    /// ```
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn or_default(self) -> &'a mut V
    where
        K: Hash,
    {
        match self {
            Occupied(entry) => entry.into_mut(),
            Vacant(entry) => entry.insert(Default::default()),
        }
    }
}

impl<'a, K, V, A: Allocator + Clone> RustcOccupiedEntry<'a, K, V, A> {
    /// Gets a reference to the key in the entry.
    ///
    /// # Examples
    ///
    /// ```
    /// use hashbrown::HashMap;
    ///
    /// let mut map: HashMap<&str, u32> = HashMap::new();
    /// map.rustc_entry("poneyland").or_insert(12);
    /// assert_eq!(map.rustc_entry("poneyland").key(), &"poneyland");
    /// ```
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn key(&self) -> &K {
        unsafe { &self.elem.as_ref().0 }
    }

    /// Take the ownership of the key and value from the map.
    ///
    /// # Examples
    ///
    /// ```
    /// use hashbrown::HashMap;
    /// use hashbrown::hash_map::RustcEntry;
    ///
    /// let mut map: HashMap<&str, u32> = HashMap::new();
    /// map.rustc_entry("poneyland").or_insert(12);
    ///
    /// if let RustcEntry::Occupied(o) = map.rustc_entry("poneyland") {
    ///     // We delete the entry from the map.
    ///     o.remove_entry();
    /// }
    ///
    /// assert_eq!(map.contains_key("poneyland"), false);
    /// ```
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn remove_entry(self) -> (K, V) {
        unsafe { self.table.remove(self.elem).0 }
    }

    /// Gets a reference to the value in the entry.
    ///
    /// # Examples
    ///
    /// ```
    /// use hashbrown::HashMap;
    /// use hashbrown::hash_map::RustcEntry;
    ///
    /// let mut map: HashMap<&str, u32> = HashMap::new();
    /// map.rustc_entry("poneyland").or_insert(12);
    ///
    /// if let RustcEntry::Occupied(o) = map.rustc_entry("poneyland") {
    ///     assert_eq!(o.get(), &12);
    /// }
    /// ```
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn get(&self) -> &V {
        unsafe { &self.elem.as_ref().1 }
    }

    /// Gets a mutable reference to the value in the entry.
    ///
    /// If you need a reference to the `RustcOccupiedEntry` which may outlive the
    /// destruction of the `RustcEntry` value, see [`into_mut`].
    ///
    /// [`into_mut`]: #method.into_mut
    ///
    /// # Examples
    ///
    /// ```
    /// use hashbrown::HashMap;
    /// use hashbrown::hash_map::RustcEntry;
    ///
    /// let mut map: HashMap<&str, u32> = HashMap::new();
    /// map.rustc_entry("poneyland").or_insert(12);
    ///
    /// assert_eq!(map["poneyland"], 12);
    /// if let RustcEntry::Occupied(mut o) = map.rustc_entry("poneyland") {
    ///     *o.get_mut() += 10;
    ///     assert_eq!(*o.get(), 22);
    ///
    ///     // We can use the same RustcEntry multiple times.
    ///     *o.get_mut() += 2;
    /// }
    ///
    /// assert_eq!(map["poneyland"], 24);
    /// ```
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn get_mut(&mut self) -> &mut V {
        unsafe { &mut self.elem.as_mut().1 }
    }

    /// Converts the RustcOccupiedEntry into a mutable reference to the value in the entry
    /// with a lifetime bound to the map itself.
    ///
    /// If you need multiple references to the `RustcOccupiedEntry`, see [`get_mut`].
    ///
    /// [`get_mut`]: #method.get_mut
    ///
    /// # Examples
    ///
    /// ```
    /// use hashbrown::HashMap;
    /// use hashbrown::hash_map::RustcEntry;
    ///
    /// let mut map: HashMap<&str, u32> = HashMap::new();
    /// map.rustc_entry("poneyland").or_insert(12);
    ///
    /// assert_eq!(map["poneyland"], 12);
    /// if let RustcEntry::Occupied(o) = map.rustc_entry("poneyland") {
    ///     *o.into_mut() += 10;
    /// }
    ///
    /// assert_eq!(map["poneyland"], 22);
    /// ```
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn into_mut(self) -> &'a mut V {
        unsafe { &mut self.elem.as_mut().1 }
    }

    /// Sets the value of the entry, and returns the entry's old value.
    ///
    /// # Examples
    ///
    /// ```
    /// use hashbrown::HashMap;
    /// use hashbrown::hash_map::RustcEntry;
    ///
    /// let mut map: HashMap<&str, u32> = HashMap::new();
    /// map.rustc_entry("poneyland").or_insert(12);
    ///
    /// if let RustcEntry::Occupied(mut o) = map.rustc_entry("poneyland") {
    ///     assert_eq!(o.insert(15), 12);
    /// }
    ///
    /// assert_eq!(map["poneyland"], 15);
    /// ```
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn insert(&mut self, value: V) -> V {
        mem::replace(self.get_mut(), value)
    }

    /// Takes the value out of the entry, and returns it.
    ///
    /// # Examples
    ///
    /// ```
    /// use hashbrown::HashMap;
    /// use hashbrown::hash_map::RustcEntry;
    ///
    /// let mut map: HashMap<&str, u32> = HashMap::new();
    /// map.rustc_entry("poneyland").or_insert(12);
    ///
    /// if let RustcEntry::Occupied(o) = map.rustc_entry("poneyland") {
    ///     assert_eq!(o.remove(), 12);
    /// }
    ///
    /// assert_eq!(map.contains_key("poneyland"), false);
    /// ```
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn remove(self) -> V {
        self.remove_entry().1
    }

    /// Replaces the entry, returning the old key and value. The new key in the hash map will be
    /// the key used to create this entry.
    ///
    /// # Examples
    ///
    /// ```
    /// use hashbrown::hash_map::{RustcEntry, HashMap};
    /// use std::rc::Rc;
    ///
    /// let mut map: HashMap<Rc<String>, u32> = HashMap::new();
    /// map.insert(Rc::new("Stringthing".to_string()), 15);
    ///
    /// let my_key = Rc::new("Stringthing".to_string());
    ///
    /// if let RustcEntry::Occupied(entry) = map.rustc_entry(my_key) {
    ///     // Also replace the key with a handle to our other key.
    ///     let (old_key, old_value): (Rc<String>, u32) = entry.replace_entry(16);
    /// }
    ///
    /// ```
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn replace_entry(self, value: V) -> (K, V) {
        let entry = unsafe { self.elem.as_mut() };

        let old_key = mem::replace(&mut entry.0, self.key.unwrap());
        let old_value = mem::replace(&mut entry.1, value);

        (old_key, old_value)
    }

    /// Replaces the key in the hash map with the key used to create this entry.
    ///
    /// # Examples
    ///
    /// ```
    /// use hashbrown::hash_map::{RustcEntry, HashMap};
    /// use std::rc::Rc;
    ///
    /// let mut map: HashMap<Rc<String>, u32> = HashMap::new();
    /// let mut known_strings: Vec<Rc<String>> = Vec::new();
    ///
    /// // Initialise known strings, run program, etc.
    ///
    /// reclaim_memory(&mut map, &known_strings);
    ///
    /// fn reclaim_memory(map: &mut HashMap<Rc<String>, u32>, known_strings: &[Rc<String>] ) {
    ///     for s in known_strings {
    ///         if let RustcEntry::Occupied(entry) = map.rustc_entry(s.clone()) {
    ///             // Replaces the entry's key with our version of it in `known_strings`.
    ///             entry.replace_key();
    ///         }
    ///     }
    /// }
    /// ```
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn replace_key(self) -> K {
        let entry = unsafe { self.elem.as_mut() };
        mem::replace(&mut entry.0, self.key.unwrap())
    }
}

impl<'a, K, V, A: Allocator + Clone> RustcVacantEntry<'a, K, V, A> {
    /// Gets a reference to the key that would be used when inserting a value
    /// through the `RustcVacantEntry`.
    ///
    /// # Examples
    ///
    /// ```
    /// use hashbrown::HashMap;
    ///
    /// let mut map: HashMap<&str, u32> = HashMap::new();
    /// assert_eq!(map.rustc_entry("poneyland").key(), &"poneyland");
    /// ```
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn key(&self) -> &K {
        &self.key
    }

    /// Take ownership of the key.
    ///
    /// # Examples
    ///
    /// ```
    /// use hashbrown::HashMap;
    /// use hashbrown::hash_map::RustcEntry;
    ///
    /// let mut map: HashMap<&str, u32> = HashMap::new();
    ///
    /// if let RustcEntry::Vacant(v) = map.rustc_entry("poneyland") {
    ///     v.into_key();
    /// }
    /// ```
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn into_key(self) -> K {
        self.key
    }

    /// Sets the value of the entry with the RustcVacantEntry's key,
    /// and returns a mutable reference to it.
    ///
    /// # Examples
    ///
    /// ```
    /// use hashbrown::HashMap;
    /// use hashbrown::hash_map::RustcEntry;
    ///
    /// let mut map: HashMap<&str, u32> = HashMap::new();
    ///
    /// if let RustcEntry::Vacant(o) = map.rustc_entry("poneyland") {
    ///     o.insert(37);
    /// }
    /// assert_eq!(map["poneyland"], 37);
    /// ```
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn insert(self, value: V) -> &'a mut V {
        unsafe {
            let bucket = self.table.insert_no_grow(self.hash, (self.key, value));
            &mut bucket.as_mut().1
        }
    }

    /// Sets the value of the entry with the RustcVacantEntry's key,
    /// and returns a RustcOccupiedEntry.
    ///
    /// # Examples
    ///
    /// ```
    /// use hashbrown::HashMap;
    /// use hashbrown::hash_map::RustcEntry;
    ///
    /// let mut map: HashMap<&str, u32> = HashMap::new();
    ///
    /// if let RustcEntry::Vacant(v) = map.rustc_entry("poneyland") {
    ///     let o = v.insert_entry(37);
    ///     assert_eq!(o.get(), &37);
    /// }
    /// ```
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn insert_entry(self, value: V) -> RustcOccupiedEntry<'a, K, V, A> {
        let bucket = unsafe { self.table.insert_no_grow(self.hash, (self.key, value)) };
        RustcOccupiedEntry {
            key: None,
            elem: bucket,
            table: self.table,
        }
    }
}

impl<K, V> IterMut<'_, K, V> {
    /// Returns a iterator of references over the remaining items.
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn rustc_iter(&self) -> Iter<'_, K, V> {
        self.iter()
    }
}

impl<K, V> IntoIter<K, V> {
    /// Returns a iterator of references over the remaining items.
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn rustc_iter(&self) -> Iter<'_, K, V> {
        self.iter()
    }
}

impl<K, V> Drain<'_, K, V> {
    /// Returns a iterator of references over the remaining items.
    #[cfg_attr(feature = "inline-more", inline)]
    pub fn rustc_iter(&self) -> Iter<'_, K, V> {
        self.iter()
    }
}