1 use crate::borrow::Borrow;
2 use crate::collections::TryReserveError;
4 use crate::hash::{Hash, BuildHasher};
5 use crate::iter::{Chain, FromIterator, FusedIterator};
6 use crate::ops::{BitOr, BitAnd, BitXor, Sub};
8 use super::map::{self, HashMap, Keys, RandomState};
10 // Future Optimization (FIXME!)
11 // ============================
13 // Iteration over zero sized values is a noop. There is no need
14 // for `bucket.val` in the case of HashSet. I suppose we would need HKT
15 // to get rid of it properly.
17 /// A hash set implemented as a `HashMap` where the value is `()`.
19 /// As with the [`HashMap`] type, a `HashSet` requires that the elements
20 /// implement the [`Eq`] and [`Hash`] traits. This can frequently be achieved by
21 /// using `#[derive(PartialEq, Eq, Hash)]`. If you implement these yourself,
22 /// it is important that the following property holds:
25 /// k1 == k2 -> hash(k1) == hash(k2)
28 /// In other words, if two keys are equal, their hashes must be equal.
31 /// It is a logic error for an item to be modified in such a way that the
32 /// item's hash, as determined by the [`Hash`] trait, or its equality, as
33 /// determined by the [`Eq`] trait, changes while it is in the set. This is
34 /// normally only possible through [`Cell`], [`RefCell`], global state, I/O, or
40 /// use std::collections::HashSet;
41 /// // Type inference lets us omit an explicit type signature (which
42 /// // would be `HashSet<String>` in this example).
43 /// let mut books = HashSet::new();
45 /// // Add some books.
46 /// books.insert("A Dance With Dragons".to_string());
47 /// books.insert("To Kill a Mockingbird".to_string());
48 /// books.insert("The Odyssey".to_string());
49 /// books.insert("The Great Gatsby".to_string());
51 /// // Check for a specific one.
52 /// if !books.contains("The Winds of Winter") {
53 /// println!("We have {} books, but The Winds of Winter ain't one.",
58 /// books.remove("The Odyssey");
60 /// // Iterate over everything.
61 /// for book in &books {
62 /// println!("{}", book);
66 /// The easiest way to use `HashSet` with a custom type is to derive
67 /// [`Eq`] and [`Hash`]. We must also derive [`PartialEq`], this will in the
68 /// future be implied by [`Eq`].
71 /// use std::collections::HashSet;
72 /// #[derive(Hash, Eq, PartialEq, Debug)]
78 /// let mut vikings = HashSet::new();
80 /// vikings.insert(Viking { name: "Einar".to_string(), power: 9 });
81 /// vikings.insert(Viking { name: "Einar".to_string(), power: 9 });
82 /// vikings.insert(Viking { name: "Olaf".to_string(), power: 4 });
83 /// vikings.insert(Viking { name: "Harald".to_string(), power: 8 });
85 /// // Use derived implementation to print the vikings.
86 /// for x in &vikings {
87 /// println!("{:?}", x);
91 /// A `HashSet` with fixed list of elements can be initialized from an array:
94 /// use std::collections::HashSet;
96 /// let viking_names: HashSet<&'static str> =
97 /// [ "Einar", "Olaf", "Harald" ].iter().cloned().collect();
98 /// // use the values stored in the set
101 /// [`Cell`]: ../../std/cell/struct.Cell.html
102 /// [`Eq`]: ../../std/cmp/trait.Eq.html
103 /// [`Hash`]: ../../std/hash/trait.Hash.html
104 /// [`HashMap`]: struct.HashMap.html
105 /// [`PartialEq`]: ../../std/cmp/trait.PartialEq.html
106 /// [`RefCell`]: ../../std/cell/struct.RefCell.html
108 #[stable(feature = "rust1", since = "1.0.0")]
109 pub struct HashSet<T, S = RandomState> {
110 map: HashMap<T, (), S>,
113 impl<T: Hash + Eq> HashSet<T, RandomState> {
114 /// Creates an empty `HashSet`.
116 /// The hash set is initially created with a capacity of 0, so it will not allocate until it
117 /// is first inserted into.
122 /// use std::collections::HashSet;
123 /// let set: HashSet<i32> = HashSet::new();
126 #[stable(feature = "rust1", since = "1.0.0")]
127 pub fn new() -> HashSet<T, RandomState> {
128 HashSet { map: HashMap::new() }
131 /// Creates an empty `HashSet` with the specified capacity.
133 /// The hash set will be able to hold at least `capacity` elements without
134 /// reallocating. If `capacity` is 0, the hash set will not allocate.
139 /// use std::collections::HashSet;
140 /// let set: HashSet<i32> = HashSet::with_capacity(10);
141 /// assert!(set.capacity() >= 10);
144 #[stable(feature = "rust1", since = "1.0.0")]
145 pub fn with_capacity(capacity: usize) -> HashSet<T, RandomState> {
146 HashSet { map: HashMap::with_capacity(capacity) }
150 impl<T, S> HashSet<T, S> {
151 /// Returns the number of elements the set can hold without reallocating.
156 /// use std::collections::HashSet;
157 /// let set: HashSet<i32> = HashSet::with_capacity(100);
158 /// assert!(set.capacity() >= 100);
161 #[stable(feature = "rust1", since = "1.0.0")]
162 pub fn capacity(&self) -> usize {
166 /// An iterator visiting all elements in arbitrary order.
167 /// The iterator element type is `&'a T`.
172 /// use std::collections::HashSet;
173 /// let mut set = HashSet::new();
177 /// // Will print in an arbitrary order.
178 /// for x in set.iter() {
179 /// println!("{}", x);
183 #[stable(feature = "rust1", since = "1.0.0")]
184 pub fn iter(&self) -> Iter<'_, T> {
185 Iter { iter: self.map.keys() }
188 /// Returns the number of elements in the set.
193 /// use std::collections::HashSet;
195 /// let mut v = HashSet::new();
196 /// assert_eq!(v.len(), 0);
198 /// assert_eq!(v.len(), 1);
201 #[stable(feature = "rust1", since = "1.0.0")]
202 pub fn len(&self) -> usize {
206 /// Returns `true` if the set contains no elements.
211 /// use std::collections::HashSet;
213 /// let mut v = HashSet::new();
214 /// assert!(v.is_empty());
216 /// assert!(!v.is_empty());
219 #[stable(feature = "rust1", since = "1.0.0")]
220 pub fn is_empty(&self) -> bool {
224 /// Clears the set, returning all elements in an iterator.
229 /// use std::collections::HashSet;
231 /// let mut set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
232 /// assert!(!set.is_empty());
234 /// // print 1, 2, 3 in an arbitrary order
235 /// for i in set.drain() {
236 /// println!("{}", i);
239 /// assert!(set.is_empty());
242 #[stable(feature = "drain", since = "1.6.0")]
243 pub fn drain(&mut self) -> Drain<'_, T> {
244 Drain { iter: self.map.drain() }
247 /// Clears the set, removing all values.
252 /// use std::collections::HashSet;
254 /// let mut v = HashSet::new();
257 /// assert!(v.is_empty());
260 #[stable(feature = "rust1", since = "1.0.0")]
261 pub fn clear(&mut self) {
266 impl<T, S> HashSet<T, S>
270 /// Creates a new empty hash set which will use the given hasher to hash
273 /// The hash set is also created with the default initial capacity.
275 /// Warning: `hasher` is normally randomly generated, and
276 /// is designed to allow `HashSet`s to be resistant to attacks that
277 /// cause many collisions and very poor performance. Setting it
278 /// manually using this function can expose a DoS attack vector.
283 /// use std::collections::HashSet;
284 /// use std::collections::hash_map::RandomState;
286 /// let s = RandomState::new();
287 /// let mut set = HashSet::with_hasher(s);
291 #[stable(feature = "hashmap_build_hasher", since = "1.7.0")]
292 pub fn with_hasher(hasher: S) -> HashSet<T, S> {
293 HashSet { map: HashMap::with_hasher(hasher) }
296 /// Creates an empty `HashSet` with the specified capacity, using
297 /// `hasher` to hash the keys.
299 /// The hash set will be able to hold at least `capacity` elements without
300 /// reallocating. If `capacity` is 0, the hash set will not allocate.
302 /// Warning: `hasher` is normally randomly generated, and
303 /// is designed to allow `HashSet`s to be resistant to attacks that
304 /// cause many collisions and very poor performance. Setting it
305 /// manually using this function can expose a DoS attack vector.
310 /// use std::collections::HashSet;
311 /// use std::collections::hash_map::RandomState;
313 /// let s = RandomState::new();
314 /// let mut set = HashSet::with_capacity_and_hasher(10, s);
318 #[stable(feature = "hashmap_build_hasher", since = "1.7.0")]
319 pub fn with_capacity_and_hasher(capacity: usize, hasher: S) -> HashSet<T, S> {
320 HashSet { map: HashMap::with_capacity_and_hasher(capacity, hasher) }
323 /// Returns a reference to the set's [`BuildHasher`].
325 /// [`BuildHasher`]: ../../std/hash/trait.BuildHasher.html
330 /// use std::collections::HashSet;
331 /// use std::collections::hash_map::RandomState;
333 /// let hasher = RandomState::new();
334 /// let set: HashSet<i32> = HashSet::with_hasher(hasher);
335 /// let hasher: &RandomState = set.hasher();
338 #[stable(feature = "hashmap_public_hasher", since = "1.9.0")]
339 pub fn hasher(&self) -> &S {
343 /// Reserves capacity for at least `additional` more elements to be inserted
344 /// in the `HashSet`. The collection may reserve more space to avoid
345 /// frequent reallocations.
349 /// Panics if the new allocation size overflows `usize`.
354 /// use std::collections::HashSet;
355 /// let mut set: HashSet<i32> = HashSet::new();
357 /// assert!(set.capacity() >= 10);
360 #[stable(feature = "rust1", since = "1.0.0")]
361 pub fn reserve(&mut self, additional: usize) {
362 self.map.reserve(additional)
365 /// Tries to reserve capacity for at least `additional` more elements to be inserted
366 /// in the given `HashSet<K,V>`. The collection may reserve more space to avoid
367 /// frequent reallocations.
371 /// If the capacity overflows, or the allocator reports a failure, then an error
377 /// #![feature(try_reserve)]
378 /// use std::collections::HashSet;
379 /// let mut set: HashSet<i32> = HashSet::new();
380 /// set.try_reserve(10).expect("why is the test harness OOMing on 10 bytes?");
383 #[unstable(feature = "try_reserve", reason = "new API", issue="48043")]
384 pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError> {
385 self.map.try_reserve(additional)
388 /// Shrinks the capacity of the set as much as possible. It will drop
389 /// down as much as possible while maintaining the internal rules
390 /// and possibly leaving some space in accordance with the resize policy.
395 /// use std::collections::HashSet;
397 /// let mut set = HashSet::with_capacity(100);
400 /// assert!(set.capacity() >= 100);
401 /// set.shrink_to_fit();
402 /// assert!(set.capacity() >= 2);
405 #[stable(feature = "rust1", since = "1.0.0")]
406 pub fn shrink_to_fit(&mut self) {
407 self.map.shrink_to_fit()
410 /// Shrinks the capacity of the set with a lower limit. It will drop
411 /// down no lower than the supplied limit while maintaining the internal rules
412 /// and possibly leaving some space in accordance with the resize policy.
414 /// Panics if the current capacity is smaller than the supplied
415 /// minimum capacity.
420 /// #![feature(shrink_to)]
421 /// use std::collections::HashSet;
423 /// let mut set = HashSet::with_capacity(100);
426 /// assert!(set.capacity() >= 100);
427 /// set.shrink_to(10);
428 /// assert!(set.capacity() >= 10);
429 /// set.shrink_to(0);
430 /// assert!(set.capacity() >= 2);
433 #[unstable(feature = "shrink_to", reason = "new API", issue="56431")]
434 pub fn shrink_to(&mut self, min_capacity: usize) {
435 self.map.shrink_to(min_capacity)
438 /// Visits the values representing the difference,
439 /// i.e., the values that are in `self` but not in `other`.
444 /// use std::collections::HashSet;
445 /// let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
446 /// let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();
448 /// // Can be seen as `a - b`.
449 /// for x in a.difference(&b) {
450 /// println!("{}", x); // Print 1
453 /// let diff: HashSet<_> = a.difference(&b).collect();
454 /// assert_eq!(diff, [1].iter().collect());
456 /// // Note that difference is not symmetric,
457 /// // and `b - a` means something else:
458 /// let diff: HashSet<_> = b.difference(&a).collect();
459 /// assert_eq!(diff, [4].iter().collect());
462 #[stable(feature = "rust1", since = "1.0.0")]
463 pub fn difference<'a>(&'a self, other: &'a HashSet<T, S>) -> Difference<'a, T, S> {
470 /// Visits the values representing the symmetric difference,
471 /// i.e., the values that are in `self` or in `other` but not in both.
476 /// use std::collections::HashSet;
477 /// let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
478 /// let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();
480 /// // Print 1, 4 in arbitrary order.
481 /// for x in a.symmetric_difference(&b) {
482 /// println!("{}", x);
485 /// let diff1: HashSet<_> = a.symmetric_difference(&b).collect();
486 /// let diff2: HashSet<_> = b.symmetric_difference(&a).collect();
488 /// assert_eq!(diff1, diff2);
489 /// assert_eq!(diff1, [1, 4].iter().collect());
492 #[stable(feature = "rust1", since = "1.0.0")]
493 pub fn symmetric_difference<'a>(&'a self,
494 other: &'a HashSet<T, S>)
495 -> SymmetricDifference<'a, T, S> {
496 SymmetricDifference { iter: self.difference(other).chain(other.difference(self)) }
499 /// Visits the values representing the intersection,
500 /// i.e., the values that are both in `self` and `other`.
505 /// use std::collections::HashSet;
506 /// let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
507 /// let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();
509 /// // Print 2, 3 in arbitrary order.
510 /// for x in a.intersection(&b) {
511 /// println!("{}", x);
514 /// let intersection: HashSet<_> = a.intersection(&b).collect();
515 /// assert_eq!(intersection, [2, 3].iter().collect());
518 #[stable(feature = "rust1", since = "1.0.0")]
519 pub fn intersection<'a>(&'a self, other: &'a HashSet<T, S>) -> Intersection<'a, T, S> {
520 if self.len() <= other.len() {
533 /// Visits the values representing the union,
534 /// i.e., all the values in `self` or `other`, without duplicates.
539 /// use std::collections::HashSet;
540 /// let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
541 /// let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();
543 /// // Print 1, 2, 3, 4 in arbitrary order.
544 /// for x in a.union(&b) {
545 /// println!("{}", x);
548 /// let union: HashSet<_> = a.union(&b).collect();
549 /// assert_eq!(union, [1, 2, 3, 4].iter().collect());
552 #[stable(feature = "rust1", since = "1.0.0")]
553 pub fn union<'a>(&'a self, other: &'a HashSet<T, S>) -> Union<'a, T, S> {
554 if self.len() <= other.len() {
556 iter: self.iter().chain(other.difference(self)),
560 iter: other.iter().chain(self.difference(other)),
565 /// Returns `true` if the set contains a value.
567 /// The value may be any borrowed form of the set's value type, but
568 /// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
574 /// use std::collections::HashSet;
576 /// let set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
577 /// assert_eq!(set.contains(&1), true);
578 /// assert_eq!(set.contains(&4), false);
581 /// [`Eq`]: ../../std/cmp/trait.Eq.html
582 /// [`Hash`]: ../../std/hash/trait.Hash.html
584 #[stable(feature = "rust1", since = "1.0.0")]
585 pub fn contains<Q: ?Sized>(&self, value: &Q) -> bool
589 self.map.contains_key(value)
592 /// Returns a reference to the value in the set, if any, that is equal to the given value.
594 /// The value may be any borrowed form of the set's value type, but
595 /// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
601 /// use std::collections::HashSet;
603 /// let set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
604 /// assert_eq!(set.get(&2), Some(&2));
605 /// assert_eq!(set.get(&4), None);
608 /// [`Eq`]: ../../std/cmp/trait.Eq.html
609 /// [`Hash`]: ../../std/hash/trait.Hash.html
611 #[stable(feature = "set_recovery", since = "1.9.0")]
612 pub fn get<Q: ?Sized>(&self, value: &Q) -> Option<&T>
616 self.map.get_key_value(value).map(|(k, _)| k)
619 /// Inserts the given `value` into the set if it is not present, then
620 /// returns a reference to the value in the set.
625 /// #![feature(hash_set_entry)]
627 /// use std::collections::HashSet;
629 /// let mut set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
630 /// assert_eq!(set.len(), 3);
631 /// assert_eq!(set.get_or_insert(2), &2);
632 /// assert_eq!(set.get_or_insert(100), &100);
633 /// assert_eq!(set.len(), 4); // 100 was inserted
636 #[unstable(feature = "hash_set_entry", issue = "60896")]
637 pub fn get_or_insert(&mut self, value: T) -> &T {
638 // Although the raw entry gives us `&mut T`, we only return `&T` to be consistent with
639 // `get`. Key mutation is "raw" because you're not supposed to affect `Eq` or `Hash`.
640 self.map.raw_entry_mut().from_key(&value).or_insert(value, ()).0
643 /// Inserts a value computed from `f` into the set if the given `value` is
644 /// not present, then returns a reference to the value in the set.
649 /// #![feature(hash_set_entry)]
651 /// use std::collections::HashSet;
653 /// let mut set: HashSet<String> = ["cat", "dog", "horse"]
654 /// .iter().map(|&pet| pet.to_owned()).collect();
656 /// assert_eq!(set.len(), 3);
657 /// for &pet in &["cat", "dog", "fish"] {
658 /// let value = set.get_or_insert_with(pet, str::to_owned);
659 /// assert_eq!(value, pet);
661 /// assert_eq!(set.len(), 4); // a new "fish" was inserted
664 #[unstable(feature = "hash_set_entry", issue = "60896")]
665 pub fn get_or_insert_with<Q: ?Sized, F>(&mut self, value: &Q, f: F) -> &T
670 // Although the raw entry gives us `&mut T`, we only return `&T` to be consistent with
671 // `get`. Key mutation is "raw" because you're not supposed to affect `Eq` or `Hash`.
672 self.map.raw_entry_mut().from_key(value).or_insert_with(|| (f(value), ())).0
675 /// Returns `true` if `self` has no elements in common with `other`.
676 /// This is equivalent to checking for an empty intersection.
681 /// use std::collections::HashSet;
683 /// let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
684 /// let mut b = HashSet::new();
686 /// assert_eq!(a.is_disjoint(&b), true);
688 /// assert_eq!(a.is_disjoint(&b), true);
690 /// assert_eq!(a.is_disjoint(&b), false);
692 #[stable(feature = "rust1", since = "1.0.0")]
693 pub fn is_disjoint(&self, other: &HashSet<T, S>) -> bool {
694 if self.len() <= other.len() {
695 self.iter().all(|v| !other.contains(v))
697 other.iter().all(|v| !self.contains(v))
701 /// Returns `true` if the set is a subset of another,
702 /// i.e., `other` contains at least all the values in `self`.
707 /// use std::collections::HashSet;
709 /// let sup: HashSet<_> = [1, 2, 3].iter().cloned().collect();
710 /// let mut set = HashSet::new();
712 /// assert_eq!(set.is_subset(&sup), true);
714 /// assert_eq!(set.is_subset(&sup), true);
716 /// assert_eq!(set.is_subset(&sup), false);
718 #[stable(feature = "rust1", since = "1.0.0")]
719 pub fn is_subset(&self, other: &HashSet<T, S>) -> bool {
720 if self.len() <= other.len() {
721 self.iter().all(|v| other.contains(v))
727 /// Returns `true` if the set is a superset of another,
728 /// i.e., `self` contains at least all the values in `other`.
733 /// use std::collections::HashSet;
735 /// let sub: HashSet<_> = [1, 2].iter().cloned().collect();
736 /// let mut set = HashSet::new();
738 /// assert_eq!(set.is_superset(&sub), false);
742 /// assert_eq!(set.is_superset(&sub), false);
745 /// assert_eq!(set.is_superset(&sub), true);
748 #[stable(feature = "rust1", since = "1.0.0")]
749 pub fn is_superset(&self, other: &HashSet<T, S>) -> bool {
750 other.is_subset(self)
753 /// Adds a value to the set.
755 /// If the set did not have this value present, `true` is returned.
757 /// If the set did have this value present, `false` is returned.
762 /// use std::collections::HashSet;
764 /// let mut set = HashSet::new();
766 /// assert_eq!(set.insert(2), true);
767 /// assert_eq!(set.insert(2), false);
768 /// assert_eq!(set.len(), 1);
771 #[stable(feature = "rust1", since = "1.0.0")]
772 pub fn insert(&mut self, value: T) -> bool {
773 self.map.insert(value, ()).is_none()
776 /// Adds a value to the set, replacing the existing value, if any, that is equal to the given
777 /// one. Returns the replaced value.
782 /// use std::collections::HashSet;
784 /// let mut set = HashSet::new();
785 /// set.insert(Vec::<i32>::new());
787 /// assert_eq!(set.get(&[][..]).unwrap().capacity(), 0);
788 /// set.replace(Vec::with_capacity(10));
789 /// assert_eq!(set.get(&[][..]).unwrap().capacity(), 10);
792 #[stable(feature = "set_recovery", since = "1.9.0")]
793 pub fn replace(&mut self, value: T) -> Option<T> {
794 match self.map.entry(value) {
795 map::Entry::Occupied(occupied) => Some(occupied.replace_key()),
796 map::Entry::Vacant(vacant) => {
803 /// Removes a value from the set. Returns whether the value was
804 /// present in the set.
806 /// The value may be any borrowed form of the set's value type, but
807 /// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
813 /// use std::collections::HashSet;
815 /// let mut set = HashSet::new();
818 /// assert_eq!(set.remove(&2), true);
819 /// assert_eq!(set.remove(&2), false);
822 /// [`Eq`]: ../../std/cmp/trait.Eq.html
823 /// [`Hash`]: ../../std/hash/trait.Hash.html
825 #[stable(feature = "rust1", since = "1.0.0")]
826 pub fn remove<Q: ?Sized>(&mut self, value: &Q) -> bool
830 self.map.remove(value).is_some()
833 /// Removes and returns the value in the set, if any, that is equal to the given one.
835 /// The value may be any borrowed form of the set's value type, but
836 /// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
842 /// use std::collections::HashSet;
844 /// let mut set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
845 /// assert_eq!(set.take(&2), Some(2));
846 /// assert_eq!(set.take(&2), None);
849 /// [`Eq`]: ../../std/cmp/trait.Eq.html
850 /// [`Hash`]: ../../std/hash/trait.Hash.html
852 #[stable(feature = "set_recovery", since = "1.9.0")]
853 pub fn take<Q: ?Sized>(&mut self, value: &Q) -> Option<T>
857 self.map.remove_entry(value).map(|(k, _)| k)
860 /// Retains only the elements specified by the predicate.
862 /// In other words, remove all elements `e` such that `f(&e)` returns `false`.
867 /// use std::collections::HashSet;
869 /// let xs = [1,2,3,4,5,6];
870 /// let mut set: HashSet<i32> = xs.iter().cloned().collect();
871 /// set.retain(|&k| k % 2 == 0);
872 /// assert_eq!(set.len(), 3);
874 #[stable(feature = "retain_hash_collection", since = "1.18.0")]
875 pub fn retain<F>(&mut self, mut f: F)
876 where F: FnMut(&T) -> bool
878 self.map.retain(|k, _| f(k));
882 #[stable(feature = "rust1", since = "1.0.0")]
883 impl<T, S> PartialEq for HashSet<T, S>
887 fn eq(&self, other: &HashSet<T, S>) -> bool {
888 if self.len() != other.len() {
892 self.iter().all(|key| other.contains(key))
896 #[stable(feature = "rust1", since = "1.0.0")]
897 impl<T, S> Eq for HashSet<T, S>
903 #[stable(feature = "rust1", since = "1.0.0")]
904 impl<T, S> fmt::Debug for HashSet<T, S>
905 where T: Eq + Hash + fmt::Debug,
908 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
909 f.debug_set().entries(self.iter()).finish()
913 #[stable(feature = "rust1", since = "1.0.0")]
914 impl<T, S> FromIterator<T> for HashSet<T, S>
916 S: BuildHasher + Default
919 fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> HashSet<T, S> {
920 let mut set = HashSet::with_hasher(Default::default());
926 #[stable(feature = "rust1", since = "1.0.0")]
927 impl<T, S> Extend<T> for HashSet<T, S>
932 fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) {
933 self.map.extend(iter.into_iter().map(|k| (k, ())));
937 #[stable(feature = "hash_extend_copy", since = "1.4.0")]
938 impl<'a, T, S> Extend<&'a T> for HashSet<T, S>
939 where T: 'a + Eq + Hash + Copy,
943 fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I) {
944 self.extend(iter.into_iter().cloned());
948 #[stable(feature = "rust1", since = "1.0.0")]
949 impl<T, S> Default for HashSet<T, S>
951 S: BuildHasher + Default
953 /// Creates an empty `HashSet<T, S>` with the `Default` value for the hasher.
955 fn default() -> HashSet<T, S> {
956 HashSet { map: HashMap::default() }
960 #[stable(feature = "rust1", since = "1.0.0")]
961 impl<T, S> BitOr<&HashSet<T, S>> for &HashSet<T, S>
962 where T: Eq + Hash + Clone,
963 S: BuildHasher + Default
965 type Output = HashSet<T, S>;
967 /// Returns the union of `self` and `rhs` as a new `HashSet<T, S>`.
972 /// use std::collections::HashSet;
974 /// let a: HashSet<_> = vec![1, 2, 3].into_iter().collect();
975 /// let b: HashSet<_> = vec![3, 4, 5].into_iter().collect();
977 /// let set = &a | &b;
980 /// let expected = [1, 2, 3, 4, 5];
982 /// assert!(expected.contains(x));
985 /// assert_eq!(i, expected.len());
987 fn bitor(self, rhs: &HashSet<T, S>) -> HashSet<T, S> {
988 self.union(rhs).cloned().collect()
992 #[stable(feature = "rust1", since = "1.0.0")]
993 impl<T, S> BitAnd<&HashSet<T, S>> for &HashSet<T, S>
994 where T: Eq + Hash + Clone,
995 S: BuildHasher + Default
997 type Output = HashSet<T, S>;
999 /// Returns the intersection of `self` and `rhs` as a new `HashSet<T, S>`.
1004 /// use std::collections::HashSet;
1006 /// let a: HashSet<_> = vec![1, 2, 3].into_iter().collect();
1007 /// let b: HashSet<_> = vec![2, 3, 4].into_iter().collect();
1009 /// let set = &a & &b;
1012 /// let expected = [2, 3];
1014 /// assert!(expected.contains(x));
1017 /// assert_eq!(i, expected.len());
1019 fn bitand(self, rhs: &HashSet<T, S>) -> HashSet<T, S> {
1020 self.intersection(rhs).cloned().collect()
1024 #[stable(feature = "rust1", since = "1.0.0")]
1025 impl<T, S> BitXor<&HashSet<T, S>> for &HashSet<T, S>
1026 where T: Eq + Hash + Clone,
1027 S: BuildHasher + Default
1029 type Output = HashSet<T, S>;
1031 /// Returns the symmetric difference of `self` and `rhs` as a new `HashSet<T, S>`.
1036 /// use std::collections::HashSet;
1038 /// let a: HashSet<_> = vec![1, 2, 3].into_iter().collect();
1039 /// let b: HashSet<_> = vec![3, 4, 5].into_iter().collect();
1041 /// let set = &a ^ &b;
1044 /// let expected = [1, 2, 4, 5];
1046 /// assert!(expected.contains(x));
1049 /// assert_eq!(i, expected.len());
1051 fn bitxor(self, rhs: &HashSet<T, S>) -> HashSet<T, S> {
1052 self.symmetric_difference(rhs).cloned().collect()
1056 #[stable(feature = "rust1", since = "1.0.0")]
1057 impl<T, S> Sub<&HashSet<T, S>> for &HashSet<T, S>
1058 where T: Eq + Hash + Clone,
1059 S: BuildHasher + Default
1061 type Output = HashSet<T, S>;
1063 /// Returns the difference of `self` and `rhs` as a new `HashSet<T, S>`.
1068 /// use std::collections::HashSet;
1070 /// let a: HashSet<_> = vec![1, 2, 3].into_iter().collect();
1071 /// let b: HashSet<_> = vec![3, 4, 5].into_iter().collect();
1073 /// let set = &a - &b;
1076 /// let expected = [1, 2];
1078 /// assert!(expected.contains(x));
1081 /// assert_eq!(i, expected.len());
1083 fn sub(self, rhs: &HashSet<T, S>) -> HashSet<T, S> {
1084 self.difference(rhs).cloned().collect()
1088 /// An iterator over the items of a `HashSet`.
1090 /// This `struct` is created by the [`iter`] method on [`HashSet`].
1091 /// See its documentation for more.
1093 /// [`HashSet`]: struct.HashSet.html
1094 /// [`iter`]: struct.HashSet.html#method.iter
1095 #[stable(feature = "rust1", since = "1.0.0")]
1096 pub struct Iter<'a, K: 'a> {
1097 iter: Keys<'a, K, ()>,
1100 /// An owning iterator over the items of a `HashSet`.
1102 /// This `struct` is created by the [`into_iter`] method on [`HashSet`][`HashSet`]
1103 /// (provided by the `IntoIterator` trait). See its documentation for more.
1105 /// [`HashSet`]: struct.HashSet.html
1106 /// [`into_iter`]: struct.HashSet.html#method.into_iter
1107 #[stable(feature = "rust1", since = "1.0.0")]
1108 pub struct IntoIter<K> {
1109 iter: map::IntoIter<K, ()>,
1112 /// A draining iterator over the items of a `HashSet`.
1114 /// This `struct` is created by the [`drain`] method on [`HashSet`].
1115 /// See its documentation for more.
1117 /// [`HashSet`]: struct.HashSet.html
1118 /// [`drain`]: struct.HashSet.html#method.drain
1119 #[stable(feature = "rust1", since = "1.0.0")]
1120 pub struct Drain<'a, K: 'a> {
1121 iter: map::Drain<'a, K, ()>,
1124 /// A lazy iterator producing elements in the intersection of `HashSet`s.
1126 /// This `struct` is created by the [`intersection`] method on [`HashSet`].
1127 /// See its documentation for more.
1129 /// [`HashSet`]: struct.HashSet.html
1130 /// [`intersection`]: struct.HashSet.html#method.intersection
1131 #[stable(feature = "rust1", since = "1.0.0")]
1132 pub struct Intersection<'a, T: 'a, S: 'a> {
1133 // iterator of the first set
1136 other: &'a HashSet<T, S>,
1139 /// A lazy iterator producing elements in the difference of `HashSet`s.
1141 /// This `struct` is created by the [`difference`] method on [`HashSet`].
1142 /// See its documentation for more.
1144 /// [`HashSet`]: struct.HashSet.html
1145 /// [`difference`]: struct.HashSet.html#method.difference
1146 #[stable(feature = "rust1", since = "1.0.0")]
1147 pub struct Difference<'a, T: 'a, S: 'a> {
1148 // iterator of the first set
1151 other: &'a HashSet<T, S>,
1154 /// A lazy iterator producing elements in the symmetric difference of `HashSet`s.
1156 /// This `struct` is created by the [`symmetric_difference`] method on
1157 /// [`HashSet`]. See its documentation for more.
1159 /// [`HashSet`]: struct.HashSet.html
1160 /// [`symmetric_difference`]: struct.HashSet.html#method.symmetric_difference
1161 #[stable(feature = "rust1", since = "1.0.0")]
1162 pub struct SymmetricDifference<'a, T: 'a, S: 'a> {
1163 iter: Chain<Difference<'a, T, S>, Difference<'a, T, S>>,
1166 /// A lazy iterator producing elements in the union of `HashSet`s.
1168 /// This `struct` is created by the [`union`] method on [`HashSet`].
1169 /// See its documentation for more.
1171 /// [`HashSet`]: struct.HashSet.html
1172 /// [`union`]: struct.HashSet.html#method.union
1173 #[stable(feature = "rust1", since = "1.0.0")]
1174 pub struct Union<'a, T: 'a, S: 'a> {
1175 iter: Chain<Iter<'a, T>, Difference<'a, T, S>>,
1178 #[stable(feature = "rust1", since = "1.0.0")]
1179 impl<'a, T, S> IntoIterator for &'a HashSet<T, S> {
1181 type IntoIter = Iter<'a, T>;
1184 fn into_iter(self) -> Iter<'a, T> {
1189 #[stable(feature = "rust1", since = "1.0.0")]
1190 impl<T, S> IntoIterator for HashSet<T, S> {
1192 type IntoIter = IntoIter<T>;
1194 /// Creates a consuming iterator, that is, one that moves each value out
1195 /// of the set in arbitrary order. The set cannot be used after calling
1201 /// use std::collections::HashSet;
1202 /// let mut set = HashSet::new();
1203 /// set.insert("a".to_string());
1204 /// set.insert("b".to_string());
1206 /// // Not possible to collect to a Vec<String> with a regular `.iter()`.
1207 /// let v: Vec<String> = set.into_iter().collect();
1209 /// // Will print in an arbitrary order.
1211 /// println!("{}", x);
1215 fn into_iter(self) -> IntoIter<T> {
1216 IntoIter { iter: self.map.into_iter() }
1220 #[stable(feature = "rust1", since = "1.0.0")]
1221 impl<K> Clone for Iter<'_, K> {
1223 fn clone(&self) -> Self {
1224 Iter { iter: self.iter.clone() }
1227 #[stable(feature = "rust1", since = "1.0.0")]
1228 impl<'a, K> Iterator for Iter<'a, K> {
1232 fn next(&mut self) -> Option<&'a K> {
1236 fn size_hint(&self) -> (usize, Option<usize>) {
1237 self.iter.size_hint()
1240 #[stable(feature = "rust1", since = "1.0.0")]
1241 impl<K> ExactSizeIterator for Iter<'_, K> {
1243 fn len(&self) -> usize {
1247 #[stable(feature = "fused", since = "1.26.0")]
1248 impl<K> FusedIterator for Iter<'_, K> {}
1250 #[stable(feature = "std_debug", since = "1.16.0")]
1251 impl<K: fmt::Debug> fmt::Debug for Iter<'_, K> {
1252 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1253 f.debug_list().entries(self.clone()).finish()
1257 #[stable(feature = "rust1", since = "1.0.0")]
1258 impl<K> Iterator for IntoIter<K> {
1262 fn next(&mut self) -> Option<K> {
1263 self.iter.next().map(|(k, _)| k)
1266 fn size_hint(&self) -> (usize, Option<usize>) {
1267 self.iter.size_hint()
1270 #[stable(feature = "rust1", since = "1.0.0")]
1271 impl<K> ExactSizeIterator for IntoIter<K> {
1273 fn len(&self) -> usize {
1277 #[stable(feature = "fused", since = "1.26.0")]
1278 impl<K> FusedIterator for IntoIter<K> {}
1280 #[stable(feature = "std_debug", since = "1.16.0")]
1281 impl<K: fmt::Debug> fmt::Debug for IntoIter<K> {
1282 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1283 let entries_iter = self.iter
1286 f.debug_list().entries(entries_iter).finish()
1290 #[stable(feature = "rust1", since = "1.0.0")]
1291 impl<'a, K> Iterator for Drain<'a, K> {
1295 fn next(&mut self) -> Option<K> {
1296 self.iter.next().map(|(k, _)| k)
1299 fn size_hint(&self) -> (usize, Option<usize>) {
1300 self.iter.size_hint()
1303 #[stable(feature = "rust1", since = "1.0.0")]
1304 impl<K> ExactSizeIterator for Drain<'_, K> {
1306 fn len(&self) -> usize {
1310 #[stable(feature = "fused", since = "1.26.0")]
1311 impl<K> FusedIterator for Drain<'_, K> {}
1313 #[stable(feature = "std_debug", since = "1.16.0")]
1314 impl<K: fmt::Debug> fmt::Debug for Drain<'_, K> {
1315 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1316 let entries_iter = self.iter
1319 f.debug_list().entries(entries_iter).finish()
1323 #[stable(feature = "rust1", since = "1.0.0")]
1324 impl<T, S> Clone for Intersection<'_, T, S> {
1326 fn clone(&self) -> Self {
1327 Intersection { iter: self.iter.clone(), ..*self }
1331 #[stable(feature = "rust1", since = "1.0.0")]
1332 impl<'a, T, S> Iterator for Intersection<'a, T, S>
1339 fn next(&mut self) -> Option<&'a T> {
1341 let elt = self.iter.next()?;
1342 if self.other.contains(elt) {
1349 fn size_hint(&self) -> (usize, Option<usize>) {
1350 let (_, upper) = self.iter.size_hint();
1355 #[stable(feature = "std_debug", since = "1.16.0")]
1356 impl<T, S> fmt::Debug for Intersection<'_, T, S>
1357 where T: fmt::Debug + Eq + Hash,
1360 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1361 f.debug_list().entries(self.clone()).finish()
1365 #[stable(feature = "fused", since = "1.26.0")]
1366 impl<T, S> FusedIterator for Intersection<'_, T, S>
1372 #[stable(feature = "rust1", since = "1.0.0")]
1373 impl<T, S> Clone for Difference<'_, T, S> {
1375 fn clone(&self) -> Self {
1376 Difference { iter: self.iter.clone(), ..*self }
1380 #[stable(feature = "rust1", since = "1.0.0")]
1381 impl<'a, T, S> Iterator for Difference<'a, T, S>
1388 fn next(&mut self) -> Option<&'a T> {
1390 let elt = self.iter.next()?;
1391 if !self.other.contains(elt) {
1398 fn size_hint(&self) -> (usize, Option<usize>) {
1399 let (_, upper) = self.iter.size_hint();
1404 #[stable(feature = "fused", since = "1.26.0")]
1405 impl<T, S> FusedIterator for Difference<'_, T, S>
1411 #[stable(feature = "std_debug", since = "1.16.0")]
1412 impl<T, S> fmt::Debug for Difference<'_, T, S>
1413 where T: fmt::Debug + Eq + Hash,
1416 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1417 f.debug_list().entries(self.clone()).finish()
1421 #[stable(feature = "rust1", since = "1.0.0")]
1422 impl<T, S> Clone for SymmetricDifference<'_, T, S> {
1424 fn clone(&self) -> Self {
1425 SymmetricDifference { iter: self.iter.clone() }
1429 #[stable(feature = "rust1", since = "1.0.0")]
1430 impl<'a, T, S> Iterator for SymmetricDifference<'a, T, S>
1437 fn next(&mut self) -> Option<&'a T> {
1441 fn size_hint(&self) -> (usize, Option<usize>) {
1442 self.iter.size_hint()
1446 #[stable(feature = "fused", since = "1.26.0")]
1447 impl<T, S> FusedIterator for SymmetricDifference<'_, T, S>
1453 #[stable(feature = "std_debug", since = "1.16.0")]
1454 impl<T, S> fmt::Debug for SymmetricDifference<'_, T, S>
1455 where T: fmt::Debug + Eq + Hash,
1458 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1459 f.debug_list().entries(self.clone()).finish()
1463 #[stable(feature = "rust1", since = "1.0.0")]
1464 impl<T, S> Clone for Union<'_, T, S> {
1466 fn clone(&self) -> Self {
1467 Union { iter: self.iter.clone() }
1471 #[stable(feature = "fused", since = "1.26.0")]
1472 impl<T, S> FusedIterator for Union<'_, T, S>
1478 #[stable(feature = "std_debug", since = "1.16.0")]
1479 impl<T, S> fmt::Debug for Union<'_, T, S>
1480 where T: fmt::Debug + Eq + Hash,
1483 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1484 f.debug_list().entries(self.clone()).finish()
1488 #[stable(feature = "rust1", since = "1.0.0")]
1489 impl<'a, T, S> Iterator for Union<'a, T, S>
1496 fn next(&mut self) -> Option<&'a T> {
1500 fn size_hint(&self) -> (usize, Option<usize>) {
1501 self.iter.size_hint()
1506 fn assert_covariance() {
1507 fn set<'new>(v: HashSet<&'static str>) -> HashSet<&'new str> {
1510 fn iter<'a, 'new>(v: Iter<'a, &'static str>) -> Iter<'a, &'new str> {
1513 fn into_iter<'new>(v: IntoIter<&'static str>) -> IntoIter<&'new str> {
1516 fn difference<'a, 'new>(v: Difference<'a, &'static str, RandomState>)
1517 -> Difference<'a, &'new str, RandomState> {
1520 fn symmetric_difference<'a, 'new>(v: SymmetricDifference<'a, &'static str, RandomState>)
1521 -> SymmetricDifference<'a, &'new str, RandomState> {
1524 fn intersection<'a, 'new>(v: Intersection<'a, &'static str, RandomState>)
1525 -> Intersection<'a, &'new str, RandomState> {
1528 fn union<'a, 'new>(v: Union<'a, &'static str, RandomState>)
1529 -> Union<'a, &'new str, RandomState> {
1532 fn drain<'new>(d: Drain<'static, &'static str>) -> Drain<'new, &'new str> {
1540 use super::super::map::RandomState;
1543 fn test_zero_capacities() {
1544 type HS = HashSet<i32>;
1547 assert_eq!(s.capacity(), 0);
1549 let s = HS::default();
1550 assert_eq!(s.capacity(), 0);
1552 let s = HS::with_hasher(RandomState::new());
1553 assert_eq!(s.capacity(), 0);
1555 let s = HS::with_capacity(0);
1556 assert_eq!(s.capacity(), 0);
1558 let s = HS::with_capacity_and_hasher(0, RandomState::new());
1559 assert_eq!(s.capacity(), 0);
1561 let mut s = HS::new();
1567 assert_eq!(s.capacity(), 0);
1569 let mut s = HS::new();
1571 assert_eq!(s.capacity(), 0);
1575 fn test_disjoint() {
1576 let mut xs = HashSet::new();
1577 let mut ys = HashSet::new();
1578 assert!(xs.is_disjoint(&ys));
1579 assert!(ys.is_disjoint(&xs));
1580 assert!(xs.insert(5));
1581 assert!(ys.insert(11));
1582 assert!(xs.is_disjoint(&ys));
1583 assert!(ys.is_disjoint(&xs));
1584 assert!(xs.insert(7));
1585 assert!(xs.insert(19));
1586 assert!(xs.insert(4));
1587 assert!(ys.insert(2));
1588 assert!(ys.insert(-11));
1589 assert!(xs.is_disjoint(&ys));
1590 assert!(ys.is_disjoint(&xs));
1591 assert!(ys.insert(7));
1592 assert!(!xs.is_disjoint(&ys));
1593 assert!(!ys.is_disjoint(&xs));
1597 fn test_subset_and_superset() {
1598 let mut a = HashSet::new();
1599 assert!(a.insert(0));
1600 assert!(a.insert(5));
1601 assert!(a.insert(11));
1602 assert!(a.insert(7));
1604 let mut b = HashSet::new();
1605 assert!(b.insert(0));
1606 assert!(b.insert(7));
1607 assert!(b.insert(19));
1608 assert!(b.insert(250));
1609 assert!(b.insert(11));
1610 assert!(b.insert(200));
1612 assert!(!a.is_subset(&b));
1613 assert!(!a.is_superset(&b));
1614 assert!(!b.is_subset(&a));
1615 assert!(!b.is_superset(&a));
1617 assert!(b.insert(5));
1619 assert!(a.is_subset(&b));
1620 assert!(!a.is_superset(&b));
1621 assert!(!b.is_subset(&a));
1622 assert!(b.is_superset(&a));
1627 let mut a = HashSet::new();
1629 assert!(a.insert(i));
1631 let mut observed: u32 = 0;
1633 observed |= 1 << *k;
1635 assert_eq!(observed, 0xFFFF_FFFF);
1639 fn test_intersection() {
1640 let mut a = HashSet::new();
1641 let mut b = HashSet::new();
1642 assert!(a.intersection(&b).next().is_none());
1644 assert!(a.insert(11));
1645 assert!(a.insert(1));
1646 assert!(a.insert(3));
1647 assert!(a.insert(77));
1648 assert!(a.insert(103));
1649 assert!(a.insert(5));
1650 assert!(a.insert(-5));
1652 assert!(b.insert(2));
1653 assert!(b.insert(11));
1654 assert!(b.insert(77));
1655 assert!(b.insert(-9));
1656 assert!(b.insert(-42));
1657 assert!(b.insert(5));
1658 assert!(b.insert(3));
1661 let expected = [3, 5, 11, 77];
1662 for x in a.intersection(&b) {
1663 assert!(expected.contains(x));
1666 assert_eq!(i, expected.len());
1668 assert!(a.insert(9)); // make a bigger than b
1671 for x in a.intersection(&b) {
1672 assert!(expected.contains(x));
1675 assert_eq!(i, expected.len());
1678 for x in b.intersection(&a) {
1679 assert!(expected.contains(x));
1682 assert_eq!(i, expected.len());
1686 fn test_difference() {
1687 let mut a = HashSet::new();
1688 let mut b = HashSet::new();
1690 assert!(a.insert(1));
1691 assert!(a.insert(3));
1692 assert!(a.insert(5));
1693 assert!(a.insert(9));
1694 assert!(a.insert(11));
1696 assert!(b.insert(3));
1697 assert!(b.insert(9));
1700 let expected = [1, 5, 11];
1701 for x in a.difference(&b) {
1702 assert!(expected.contains(x));
1705 assert_eq!(i, expected.len());
1709 fn test_symmetric_difference() {
1710 let mut a = HashSet::new();
1711 let mut b = HashSet::new();
1713 assert!(a.insert(1));
1714 assert!(a.insert(3));
1715 assert!(a.insert(5));
1716 assert!(a.insert(9));
1717 assert!(a.insert(11));
1719 assert!(b.insert(-2));
1720 assert!(b.insert(3));
1721 assert!(b.insert(9));
1722 assert!(b.insert(14));
1723 assert!(b.insert(22));
1726 let expected = [-2, 1, 5, 11, 14, 22];
1727 for x in a.symmetric_difference(&b) {
1728 assert!(expected.contains(x));
1731 assert_eq!(i, expected.len());
1736 let mut a = HashSet::new();
1737 let mut b = HashSet::new();
1738 assert!(a.union(&b).next().is_none());
1739 assert!(b.union(&a).next().is_none());
1741 assert!(a.insert(1));
1742 assert!(a.insert(3));
1743 assert!(a.insert(11));
1744 assert!(a.insert(16));
1745 assert!(a.insert(19));
1746 assert!(a.insert(24));
1748 assert!(b.insert(-2));
1749 assert!(b.insert(1));
1750 assert!(b.insert(5));
1751 assert!(b.insert(9));
1752 assert!(b.insert(13));
1753 assert!(b.insert(19));
1756 let expected = [-2, 1, 3, 5, 9, 11, 13, 16, 19, 24];
1757 for x in a.union(&b) {
1758 assert!(expected.contains(x));
1761 assert_eq!(i, expected.len());
1763 assert!(a.insert(9)); // make a bigger than b
1764 assert!(a.insert(5));
1767 for x in a.union(&b) {
1768 assert!(expected.contains(x));
1771 assert_eq!(i, expected.len());
1774 for x in b.union(&a) {
1775 assert!(expected.contains(x));
1778 assert_eq!(i, expected.len());
1782 fn test_from_iter() {
1783 let xs = [1, 2, 2, 3, 4, 5, 6, 7, 8, 9];
1785 let set: HashSet<_> = xs.iter().cloned().collect();
1788 assert!(set.contains(x));
1791 assert_eq!(set.iter().len(), xs.len() - 1);
1795 fn test_move_iter() {
1797 let mut hs = HashSet::new();
1805 let v = hs.into_iter().collect::<Vec<char>>();
1806 assert!(v == ['a', 'b'] || v == ['b', 'a']);
1811 // These constants once happened to expose a bug in insert().
1812 // I'm keeping them around to prevent a regression.
1813 let mut s1 = HashSet::new();
1819 let mut s2 = HashSet::new();
1833 let mut set = HashSet::new();
1834 let empty = HashSet::<i32>::new();
1839 let set_str = format!("{:?}", set);
1841 assert!(set_str == "{1, 2}" || set_str == "{2, 1}");
1842 assert_eq!(format!("{:?}", empty), "{}");
1846 fn test_trivial_drain() {
1847 let mut s = HashSet::<i32>::new();
1848 for _ in s.drain() {}
1849 assert!(s.is_empty());
1852 let mut s = HashSet::<i32>::new();
1854 assert!(s.is_empty());
1859 let mut s: HashSet<_> = (1..100).collect();
1861 // try this a bunch of times to make sure we don't screw up internal state.
1863 assert_eq!(s.len(), 99);
1867 let mut d = s.drain();
1868 for (i, x) in d.by_ref().take(50).enumerate() {
1872 assert_eq!(last_i, 49);
1876 panic!("s should be empty!");
1879 // reset to try again.
1889 struct Foo(&'static str, i32);
1891 impl PartialEq for Foo {
1892 fn eq(&self, other: &Self) -> bool {
1899 impl hash::Hash for Foo {
1900 fn hash<H: hash::Hasher>(&self, h: &mut H) {
1905 let mut s = HashSet::new();
1906 assert_eq!(s.replace(Foo("a", 1)), None);
1907 assert_eq!(s.len(), 1);
1908 assert_eq!(s.replace(Foo("a", 2)), Some(Foo("a", 1)));
1909 assert_eq!(s.len(), 1);
1911 let mut it = s.iter();
1912 assert_eq!(it.next(), Some(&Foo("a", 2)));
1913 assert_eq!(it.next(), None);
1917 fn test_extend_ref() {
1918 let mut a = HashSet::new();
1921 a.extend(&[2, 3, 4]);
1923 assert_eq!(a.len(), 4);
1924 assert!(a.contains(&1));
1925 assert!(a.contains(&2));
1926 assert!(a.contains(&3));
1927 assert!(a.contains(&4));
1929 let mut b = HashSet::new();
1935 assert_eq!(a.len(), 6);
1936 assert!(a.contains(&1));
1937 assert!(a.contains(&2));
1938 assert!(a.contains(&3));
1939 assert!(a.contains(&4));
1940 assert!(a.contains(&5));
1941 assert!(a.contains(&6));
1946 let xs = [1, 2, 3, 4, 5, 6];
1947 let mut set: HashSet<i32> = xs.iter().cloned().collect();
1948 set.retain(|&k| k % 2 == 0);
1949 assert_eq!(set.len(), 3);
1950 assert!(set.contains(&2));
1951 assert!(set.contains(&4));
1952 assert!(set.contains(&6));