pub struct HashSet<T, S = DefaultHashBuilder, A: Allocator + Clone = Global> { /* private fields */ }
Expand description
A hash set implemented as a HashMap
where the value is ()
.
As with the HashMap
type, a HashSet
requires that the elements
implement the Eq
and Hash
traits. This can frequently be achieved by
using #[derive(PartialEq, Eq, Hash)]
. If you implement these yourself,
it is important that the following property holds:
k1 == k2 -> hash(k1) == hash(k2)
In other words, if two keys are equal, their hashes must be equal.
It is a logic error for an item to be modified in such a way that the
item’s hash, as determined by the Hash
trait, or its equality, as
determined by the Eq
trait, changes while it is in the set. This is
normally only possible through Cell
, RefCell
, global state, I/O, or
unsafe code.
It is also a logic error for the Hash
implementation of a key to panic.
This is generally only possible if the trait is implemented manually. If a
panic does occur then the contents of the HashSet
may become corrupted and
some items may be dropped from the table.
Examples
use hashbrown::HashSet;
// Type inference lets us omit an explicit type signature (which
// would be `HashSet<String>` in this example).
let mut books = HashSet::new();
// Add some books.
books.insert("A Dance With Dragons".to_string());
books.insert("To Kill a Mockingbird".to_string());
books.insert("The Odyssey".to_string());
books.insert("The Great Gatsby".to_string());
// Check for a specific one.
if !books.contains("The Winds of Winter") {
println!("We have {} books, but The Winds of Winter ain't one.",
books.len());
}
// Remove a book.
books.remove("The Odyssey");
// Iterate over everything.
for book in &books {
println!("{}", book);
}
The easiest way to use HashSet
with a custom type is to derive
Eq
and Hash
. We must also derive PartialEq
. This will in the
future be implied by Eq
.
use hashbrown::HashSet;
#[derive(Hash, Eq, PartialEq, Debug)]
struct Viking {
name: String,
power: usize,
}
let mut vikings = HashSet::new();
vikings.insert(Viking { name: "Einar".to_string(), power: 9 });
vikings.insert(Viking { name: "Einar".to_string(), power: 9 });
vikings.insert(Viking { name: "Olaf".to_string(), power: 4 });
vikings.insert(Viking { name: "Harald".to_string(), power: 8 });
// Use derived implementation to print the vikings.
for x in &vikings {
println!("{:?}", x);
}
A HashSet
with fixed list of elements can be initialized from an array:
use hashbrown::HashSet;
let viking_names: HashSet<&'static str> =
[ "Einar", "Olaf", "Harald" ].iter().cloned().collect();
// use the values stored in the set
Implementations
sourceimpl<T> HashSet<T, DefaultHashBuilder>
impl<T> HashSet<T, DefaultHashBuilder>
sourcepub fn new() -> Self
pub fn new() -> Self
Creates an empty HashSet
.
The hash set is initially created with a capacity of 0, so it will not allocate until it is first inserted into.
Examples
use hashbrown::HashSet;
let set: HashSet<i32> = HashSet::new();
sourcepub fn with_capacity(capacity: usize) -> Self
pub fn with_capacity(capacity: usize) -> Self
Creates an empty HashSet
with the specified capacity.
The hash set will be able to hold at least capacity
elements without
reallocating. If capacity
is 0, the hash set will not allocate.
Examples
use hashbrown::HashSet;
let set: HashSet<i32> = HashSet::with_capacity(10);
assert!(set.capacity() >= 10);
sourceimpl<T: Hash + Eq, A: Allocator + Clone> HashSet<T, DefaultHashBuilder, A>
impl<T: Hash + Eq, A: Allocator + Clone> HashSet<T, DefaultHashBuilder, A>
sourcepub fn new_in(alloc: A) -> Self
pub fn new_in(alloc: A) -> Self
Creates an empty HashSet
.
The hash set is initially created with a capacity of 0, so it will not allocate until it is first inserted into.
Examples
use hashbrown::HashSet;
let set: HashSet<i32> = HashSet::new();
sourcepub fn with_capacity_in(capacity: usize, alloc: A) -> Self
pub fn with_capacity_in(capacity: usize, alloc: A) -> Self
Creates an empty HashSet
with the specified capacity.
The hash set will be able to hold at least capacity
elements without
reallocating. If capacity
is 0, the hash set will not allocate.
Examples
use hashbrown::HashSet;
let set: HashSet<i32> = HashSet::with_capacity(10);
assert!(set.capacity() >= 10);
sourceimpl<T, S, A: Allocator + Clone> HashSet<T, S, A>
impl<T, S, A: Allocator + Clone> HashSet<T, S, A>
sourcepub fn capacity(&self) -> usize
pub fn capacity(&self) -> usize
Returns the number of elements the set can hold without reallocating.
Examples
use hashbrown::HashSet;
let set: HashSet<i32> = HashSet::with_capacity(100);
assert!(set.capacity() >= 100);
sourcepub fn iter(&self) -> Iter<'_, T>ⓘNotable traits for Iter<'a, K>impl<'a, K> Iterator for Iter<'a, K> type Item = &'a K;
pub fn iter(&self) -> Iter<'_, T>ⓘNotable traits for Iter<'a, K>impl<'a, K> Iterator for Iter<'a, K> type Item = &'a K;
An iterator visiting all elements in arbitrary order.
The iterator element type is &'a T
.
Examples
use hashbrown::HashSet;
let mut set = HashSet::new();
set.insert("a");
set.insert("b");
// Will print in an arbitrary order.
for x in set.iter() {
println!("{}", x);
}
sourcepub fn len(&self) -> usize
pub fn len(&self) -> usize
Returns the number of elements in the set.
Examples
use hashbrown::HashSet;
let mut v = HashSet::new();
assert_eq!(v.len(), 0);
v.insert(1);
assert_eq!(v.len(), 1);
sourcepub fn is_empty(&self) -> bool
pub fn is_empty(&self) -> bool
Returns true
if the set contains no elements.
Examples
use hashbrown::HashSet;
let mut v = HashSet::new();
assert!(v.is_empty());
v.insert(1);
assert!(!v.is_empty());
sourcepub fn drain(&mut self) -> Drain<'_, T, A>ⓘNotable traits for Drain<'_, K, A>impl<K, A: Allocator + Clone> Iterator for Drain<'_, K, A> type Item = K;
pub fn drain(&mut self) -> Drain<'_, T, A>ⓘNotable traits for Drain<'_, K, A>impl<K, A: Allocator + Clone> Iterator for Drain<'_, K, A> type Item = K;
Clears the set, returning all elements in an iterator.
Examples
use hashbrown::HashSet;
let mut set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
assert!(!set.is_empty());
// print 1, 2, 3 in an arbitrary order
for i in set.drain() {
println!("{}", i);
}
assert!(set.is_empty());
sourcepub fn retain<F>(&mut self, f: F) where
F: FnMut(&T) -> bool,
pub fn retain<F>(&mut self, f: F) where
F: FnMut(&T) -> bool,
Retains only the elements specified by the predicate.
In other words, remove all elements e
such that f(&e)
returns false
.
Examples
use hashbrown::HashSet;
let xs = [1,2,3,4,5,6];
let mut set: HashSet<i32> = xs.iter().cloned().collect();
set.retain(|&k| k % 2 == 0);
assert_eq!(set.len(), 3);
sourcepub fn drain_filter<F>(&mut self, f: F) -> DrainFilter<'_, T, F, A>ⓘNotable traits for DrainFilter<'_, K, F, A>impl<K, F, A: Allocator + Clone> Iterator for DrainFilter<'_, K, F, A> where
F: FnMut(&K) -> bool, type Item = K;
where
F: FnMut(&T) -> bool,
pub fn drain_filter<F>(&mut self, f: F) -> DrainFilter<'_, T, F, A>ⓘNotable traits for DrainFilter<'_, K, F, A>impl<K, F, A: Allocator + Clone> Iterator for DrainFilter<'_, K, F, A> where
F: FnMut(&K) -> bool, type Item = K;
where
F: FnMut(&T) -> bool,
F: FnMut(&K) -> bool, type Item = K;
Drains elements which are true under the given predicate, and returns an iterator over the removed items.
In other words, move all elements e
such that f(&e)
returns true
out
into another iterator.
When the returned DrainedFilter is dropped, any remaining elements that satisfy the predicate are dropped from the set.
Examples
use hashbrown::HashSet;
let mut set: HashSet<i32> = (0..8).collect();
let drained: HashSet<i32> = set.drain_filter(|v| v % 2 == 0).collect();
let mut evens = drained.into_iter().collect::<Vec<_>>();
let mut odds = set.into_iter().collect::<Vec<_>>();
evens.sort();
odds.sort();
assert_eq!(evens, vec![0, 2, 4, 6]);
assert_eq!(odds, vec![1, 3, 5, 7]);
sourceimpl<T, S> HashSet<T, S, Global>
impl<T, S> HashSet<T, S, Global>
sourcepub const fn with_hasher(hasher: S) -> Self
pub const fn with_hasher(hasher: S) -> Self
Creates a new empty hash set which will use the given hasher to hash keys.
The hash set is also created with the default initial capacity.
Warning: hasher
is normally randomly generated, and
is designed to allow HashSet
s to be resistant to attacks that
cause many collisions and very poor performance. Setting it
manually using this function can expose a DoS attack vector.
The hash_builder
passed should implement the BuildHasher
trait for
the HashMap to be useful, see its documentation for details.
Examples
use hashbrown::HashSet;
use hashbrown::hash_map::DefaultHashBuilder;
let s = DefaultHashBuilder::default();
let mut set = HashSet::with_hasher(s);
set.insert(2);
sourcepub fn with_capacity_and_hasher(capacity: usize, hasher: S) -> Self
pub fn with_capacity_and_hasher(capacity: usize, hasher: S) -> Self
Creates an empty HashSet
with the specified capacity, using
hasher
to hash the keys.
The hash set will be able to hold at least capacity
elements without
reallocating. If capacity
is 0, the hash set will not allocate.
Warning: hasher
is normally randomly generated, and
is designed to allow HashSet
s to be resistant to attacks that
cause many collisions and very poor performance. Setting it
manually using this function can expose a DoS attack vector.
The hash_builder
passed should implement the BuildHasher
trait for
the HashMap to be useful, see its documentation for details.
Examples
use hashbrown::HashSet;
use hashbrown::hash_map::DefaultHashBuilder;
let s = DefaultHashBuilder::default();
let mut set = HashSet::with_capacity_and_hasher(10, s);
set.insert(1);
sourceimpl<T, S, A> HashSet<T, S, A> where
A: Allocator + Clone,
impl<T, S, A> HashSet<T, S, A> where
A: Allocator + Clone,
sourcepub fn with_hasher_in(hasher: S, alloc: A) -> Self
pub fn with_hasher_in(hasher: S, alloc: A) -> Self
Creates a new empty hash set which will use the given hasher to hash keys.
The hash set is also created with the default initial capacity.
Warning: hasher
is normally randomly generated, and
is designed to allow HashSet
s to be resistant to attacks that
cause many collisions and very poor performance. Setting it
manually using this function can expose a DoS attack vector.
Examples
use hashbrown::HashSet;
use hashbrown::hash_map::DefaultHashBuilder;
let s = DefaultHashBuilder::default();
let mut set = HashSet::with_hasher(s);
set.insert(2);
sourcepub fn with_capacity_and_hasher_in(capacity: usize, hasher: S, alloc: A) -> Self
pub fn with_capacity_and_hasher_in(capacity: usize, hasher: S, alloc: A) -> Self
Creates an empty HashSet
with the specified capacity, using
hasher
to hash the keys.
The hash set will be able to hold at least capacity
elements without
reallocating. If capacity
is 0, the hash set will not allocate.
Warning: hasher
is normally randomly generated, and
is designed to allow HashSet
s to be resistant to attacks that
cause many collisions and very poor performance. Setting it
manually using this function can expose a DoS attack vector.
Examples
use hashbrown::HashSet;
use hashbrown::hash_map::DefaultHashBuilder;
let s = DefaultHashBuilder::default();
let mut set = HashSet::with_capacity_and_hasher(10, s);
set.insert(1);
sourcepub fn hasher(&self) -> &S
pub fn hasher(&self) -> &S
Returns a reference to the set’s BuildHasher
.
Examples
use hashbrown::HashSet;
use hashbrown::hash_map::DefaultHashBuilder;
let hasher = DefaultHashBuilder::default();
let set: HashSet<i32> = HashSet::with_hasher(hasher);
let hasher: &DefaultHashBuilder = set.hasher();
sourceimpl<T, S, A> HashSet<T, S, A> where
T: Eq + Hash,
S: BuildHasher,
A: Allocator + Clone,
impl<T, S, A> HashSet<T, S, A> where
T: Eq + Hash,
S: BuildHasher,
A: Allocator + Clone,
sourcepub fn reserve(&mut self, additional: usize)
pub fn reserve(&mut self, additional: usize)
Reserves capacity for at least additional
more elements to be inserted
in the HashSet
. The collection may reserve more space to avoid
frequent reallocations.
Panics
Panics if the new allocation size overflows usize
.
Examples
use hashbrown::HashSet;
let mut set: HashSet<i32> = HashSet::new();
set.reserve(10);
assert!(set.capacity() >= 10);
sourcepub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError>
pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError>
Tries to reserve capacity for at least additional
more elements to be inserted
in the given HashSet<K,V>
. The collection may reserve more space to avoid
frequent reallocations.
Errors
If the capacity overflows, or the allocator reports a failure, then an error is returned.
Examples
use hashbrown::HashSet;
let mut set: HashSet<i32> = HashSet::new();
set.try_reserve(10).expect("why is the test harness OOMing on 10 bytes?");
sourcepub fn shrink_to_fit(&mut self)
pub fn shrink_to_fit(&mut self)
Shrinks the capacity of the set as much as possible. It will drop down as much as possible while maintaining the internal rules and possibly leaving some space in accordance with the resize policy.
Examples
use hashbrown::HashSet;
let mut set = HashSet::with_capacity(100);
set.insert(1);
set.insert(2);
assert!(set.capacity() >= 100);
set.shrink_to_fit();
assert!(set.capacity() >= 2);
sourcepub fn shrink_to(&mut self, min_capacity: usize)
pub fn shrink_to(&mut self, min_capacity: usize)
Shrinks the capacity of the set with a lower limit. It will drop down no lower than the supplied limit while maintaining the internal rules and possibly leaving some space in accordance with the resize policy.
Panics if the current capacity is smaller than the supplied minimum capacity.
Examples
use hashbrown::HashSet;
let mut set = HashSet::with_capacity(100);
set.insert(1);
set.insert(2);
assert!(set.capacity() >= 100);
set.shrink_to(10);
assert!(set.capacity() >= 10);
set.shrink_to(0);
assert!(set.capacity() >= 2);
sourcepub fn difference<'a>(&'a self, other: &'a Self) -> Difference<'a, T, S, A>ⓘNotable traits for Difference<'a, T, S, A>impl<'a, T, S, A> Iterator for Difference<'a, T, S, A> where
T: Eq + Hash,
S: BuildHasher,
A: Allocator + Clone, type Item = &'a T;
pub fn difference<'a>(&'a self, other: &'a Self) -> Difference<'a, T, S, A>ⓘNotable traits for Difference<'a, T, S, A>impl<'a, T, S, A> Iterator for Difference<'a, T, S, A> where
T: Eq + Hash,
S: BuildHasher,
A: Allocator + Clone, type Item = &'a T;
T: Eq + Hash,
S: BuildHasher,
A: Allocator + Clone, type Item = &'a T;
Visits the values representing the difference,
i.e., the values that are in self
but not in other
.
Examples
use hashbrown::HashSet;
let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();
// Can be seen as `a - b`.
for x in a.difference(&b) {
println!("{}", x); // Print 1
}
let diff: HashSet<_> = a.difference(&b).collect();
assert_eq!(diff, [1].iter().collect());
// Note that difference is not symmetric,
// and `b - a` means something else:
let diff: HashSet<_> = b.difference(&a).collect();
assert_eq!(diff, [4].iter().collect());
sourcepub fn symmetric_difference<'a>(
&'a self,
other: &'a Self
) -> SymmetricDifference<'a, T, S, A>ⓘNotable traits for SymmetricDifference<'a, T, S, A>impl<'a, T, S, A> Iterator for SymmetricDifference<'a, T, S, A> where
T: Eq + Hash,
S: BuildHasher,
A: Allocator + Clone, type Item = &'a T;
pub fn symmetric_difference<'a>(
&'a self,
other: &'a Self
) -> SymmetricDifference<'a, T, S, A>ⓘNotable traits for SymmetricDifference<'a, T, S, A>impl<'a, T, S, A> Iterator for SymmetricDifference<'a, T, S, A> where
T: Eq + Hash,
S: BuildHasher,
A: Allocator + Clone, type Item = &'a T;
T: Eq + Hash,
S: BuildHasher,
A: Allocator + Clone, type Item = &'a T;
Visits the values representing the symmetric difference,
i.e., the values that are in self
or in other
but not in both.
Examples
use hashbrown::HashSet;
let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();
// Print 1, 4 in arbitrary order.
for x in a.symmetric_difference(&b) {
println!("{}", x);
}
let diff1: HashSet<_> = a.symmetric_difference(&b).collect();
let diff2: HashSet<_> = b.symmetric_difference(&a).collect();
assert_eq!(diff1, diff2);
assert_eq!(diff1, [1, 4].iter().collect());
sourcepub fn intersection<'a>(&'a self, other: &'a Self) -> Intersection<'a, T, S, A>ⓘNotable traits for Intersection<'a, T, S, A>impl<'a, T, S, A> Iterator for Intersection<'a, T, S, A> where
T: Eq + Hash,
S: BuildHasher,
A: Allocator + Clone, type Item = &'a T;
pub fn intersection<'a>(&'a self, other: &'a Self) -> Intersection<'a, T, S, A>ⓘNotable traits for Intersection<'a, T, S, A>impl<'a, T, S, A> Iterator for Intersection<'a, T, S, A> where
T: Eq + Hash,
S: BuildHasher,
A: Allocator + Clone, type Item = &'a T;
T: Eq + Hash,
S: BuildHasher,
A: Allocator + Clone, type Item = &'a T;
Visits the values representing the intersection,
i.e., the values that are both in self
and other
.
Examples
use hashbrown::HashSet;
let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();
// Print 2, 3 in arbitrary order.
for x in a.intersection(&b) {
println!("{}", x);
}
let intersection: HashSet<_> = a.intersection(&b).collect();
assert_eq!(intersection, [2, 3].iter().collect());
sourcepub fn union<'a>(&'a self, other: &'a Self) -> Union<'a, T, S, A>ⓘNotable traits for Union<'a, T, S, A>impl<'a, T, S, A> Iterator for Union<'a, T, S, A> where
T: Eq + Hash,
S: BuildHasher,
A: Allocator + Clone, type Item = &'a T;
pub fn union<'a>(&'a self, other: &'a Self) -> Union<'a, T, S, A>ⓘNotable traits for Union<'a, T, S, A>impl<'a, T, S, A> Iterator for Union<'a, T, S, A> where
T: Eq + Hash,
S: BuildHasher,
A: Allocator + Clone, type Item = &'a T;
T: Eq + Hash,
S: BuildHasher,
A: Allocator + Clone, type Item = &'a T;
Visits the values representing the union,
i.e., all the values in self
or other
, without duplicates.
Examples
use hashbrown::HashSet;
let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();
// Print 1, 2, 3, 4 in arbitrary order.
for x in a.union(&b) {
println!("{}", x);
}
let union: HashSet<_> = a.union(&b).collect();
assert_eq!(union, [1, 2, 3, 4].iter().collect());
sourcepub fn contains<Q: ?Sized>(&self, value: &Q) -> bool where
T: Borrow<Q>,
Q: Hash + Eq,
pub fn contains<Q: ?Sized>(&self, value: &Q) -> bool where
T: Borrow<Q>,
Q: Hash + Eq,
Returns true
if the set contains a value.
The value may be any borrowed form of the set’s value type, but
Hash
and Eq
on the borrowed form must match those for
the value type.
Examples
use hashbrown::HashSet;
let set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
assert_eq!(set.contains(&1), true);
assert_eq!(set.contains(&4), false);
sourcepub fn get<Q: ?Sized>(&self, value: &Q) -> Option<&T> where
T: Borrow<Q>,
Q: Hash + Eq,
pub fn get<Q: ?Sized>(&self, value: &Q) -> Option<&T> where
T: Borrow<Q>,
Q: Hash + Eq,
Returns a reference to the value in the set, if any, that is equal to the given value.
The value may be any borrowed form of the set’s value type, but
Hash
and Eq
on the borrowed form must match those for
the value type.
Examples
use hashbrown::HashSet;
let set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
assert_eq!(set.get(&2), Some(&2));
assert_eq!(set.get(&4), None);
sourcepub fn get_or_insert(&mut self, value: T) -> &T
pub fn get_or_insert(&mut self, value: T) -> &T
Inserts the given value
into the set if it is not present, then
returns a reference to the value in the set.
Examples
use hashbrown::HashSet;
let mut set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
assert_eq!(set.len(), 3);
assert_eq!(set.get_or_insert(2), &2);
assert_eq!(set.get_or_insert(100), &100);
assert_eq!(set.len(), 4); // 100 was inserted
sourcepub fn get_or_insert_owned<Q: ?Sized>(&mut self, value: &Q) -> &T where
T: Borrow<Q>,
Q: Hash + Eq + ToOwned<Owned = T>,
pub fn get_or_insert_owned<Q: ?Sized>(&mut self, value: &Q) -> &T where
T: Borrow<Q>,
Q: Hash + Eq + ToOwned<Owned = T>,
Inserts an owned copy of the given value
into the set if it is not
present, then returns a reference to the value in the set.
Examples
use hashbrown::HashSet;
let mut set: HashSet<String> = ["cat", "dog", "horse"]
.iter().map(|&pet| pet.to_owned()).collect();
assert_eq!(set.len(), 3);
for &pet in &["cat", "dog", "fish"] {
let value = set.get_or_insert_owned(pet);
assert_eq!(value, pet);
}
assert_eq!(set.len(), 4); // a new "fish" was inserted
sourcepub fn get_or_insert_with<Q: ?Sized, F>(&mut self, value: &Q, f: F) -> &T where
T: Borrow<Q>,
Q: Hash + Eq,
F: FnOnce(&Q) -> T,
pub fn get_or_insert_with<Q: ?Sized, F>(&mut self, value: &Q, f: F) -> &T where
T: Borrow<Q>,
Q: Hash + Eq,
F: FnOnce(&Q) -> T,
Inserts a value computed from f
into the set if the given value
is
not present, then returns a reference to the value in the set.
Examples
use hashbrown::HashSet;
let mut set: HashSet<String> = ["cat", "dog", "horse"]
.iter().map(|&pet| pet.to_owned()).collect();
assert_eq!(set.len(), 3);
for &pet in &["cat", "dog", "fish"] {
let value = set.get_or_insert_with(pet, str::to_owned);
assert_eq!(value, pet);
}
assert_eq!(set.len(), 4); // a new "fish" was inserted
sourcepub fn is_disjoint(&self, other: &Self) -> bool
pub fn is_disjoint(&self, other: &Self) -> bool
Returns true
if self
has no elements in common with other
.
This is equivalent to checking for an empty intersection.
Examples
use hashbrown::HashSet;
let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
let mut b = HashSet::new();
assert_eq!(a.is_disjoint(&b), true);
b.insert(4);
assert_eq!(a.is_disjoint(&b), true);
b.insert(1);
assert_eq!(a.is_disjoint(&b), false);
sourcepub fn is_subset(&self, other: &Self) -> bool
pub fn is_subset(&self, other: &Self) -> bool
Returns true
if the set is a subset of another,
i.e., other
contains at least all the values in self
.
Examples
use hashbrown::HashSet;
let sup: HashSet<_> = [1, 2, 3].iter().cloned().collect();
let mut set = HashSet::new();
assert_eq!(set.is_subset(&sup), true);
set.insert(2);
assert_eq!(set.is_subset(&sup), true);
set.insert(4);
assert_eq!(set.is_subset(&sup), false);
sourcepub fn is_superset(&self, other: &Self) -> bool
pub fn is_superset(&self, other: &Self) -> bool
Returns true
if the set is a superset of another,
i.e., self
contains at least all the values in other
.
Examples
use hashbrown::HashSet;
let sub: HashSet<_> = [1, 2].iter().cloned().collect();
let mut set = HashSet::new();
assert_eq!(set.is_superset(&sub), false);
set.insert(0);
set.insert(1);
assert_eq!(set.is_superset(&sub), false);
set.insert(2);
assert_eq!(set.is_superset(&sub), true);
sourcepub fn insert(&mut self, value: T) -> bool
pub fn insert(&mut self, value: T) -> bool
Adds a value to the set.
If the set did not have this value present, true
is returned.
If the set did have this value present, false
is returned.
Examples
use hashbrown::HashSet;
let mut set = HashSet::new();
assert_eq!(set.insert(2), true);
assert_eq!(set.insert(2), false);
assert_eq!(set.len(), 1);
sourcepub fn insert_unique_unchecked(&mut self, value: T) -> &T
pub fn insert_unique_unchecked(&mut self, value: T) -> &T
Insert a value the set without checking if the value already exists in the set.
Returns a reference to the value just inserted.
This operation is safe if a value does not exist in the set.
However, if a value exists in the set already, the behavior is unspecified: this operation may panic, loop forever, or any following operation with the set may panic, loop forever or return arbitrary result.
That said, this operation (and following operations) are guaranteed to not violate memory safety.
This operation is faster than regular insert, because it does not perform lookup before insertion.
This operation is useful during initial population of the set. For example, when constructing a set from another set, we know that values are unique.
sourcepub fn replace(&mut self, value: T) -> Option<T>
pub fn replace(&mut self, value: T) -> Option<T>
Adds a value to the set, replacing the existing value, if any, that is equal to the given one. Returns the replaced value.
Examples
use hashbrown::HashSet;
let mut set = HashSet::new();
set.insert(Vec::<i32>::new());
assert_eq!(set.get(&[][..]).unwrap().capacity(), 0);
set.replace(Vec::with_capacity(10));
assert_eq!(set.get(&[][..]).unwrap().capacity(), 10);
sourcepub fn remove<Q: ?Sized>(&mut self, value: &Q) -> bool where
T: Borrow<Q>,
Q: Hash + Eq,
pub fn remove<Q: ?Sized>(&mut self, value: &Q) -> bool where
T: Borrow<Q>,
Q: Hash + Eq,
Removes a value from the set. Returns whether the value was present in the set.
The value may be any borrowed form of the set’s value type, but
Hash
and Eq
on the borrowed form must match those for
the value type.
Examples
use hashbrown::HashSet;
let mut set = HashSet::new();
set.insert(2);
assert_eq!(set.remove(&2), true);
assert_eq!(set.remove(&2), false);
sourcepub fn take<Q: ?Sized>(&mut self, value: &Q) -> Option<T> where
T: Borrow<Q>,
Q: Hash + Eq,
pub fn take<Q: ?Sized>(&mut self, value: &Q) -> Option<T> where
T: Borrow<Q>,
Q: Hash + Eq,
Removes and returns the value in the set, if any, that is equal to the given one.
The value may be any borrowed form of the set’s value type, but
Hash
and Eq
on the borrowed form must match those for
the value type.
Examples
use hashbrown::HashSet;
let mut set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
assert_eq!(set.take(&2), Some(2));
assert_eq!(set.take(&2), None);
Trait Implementations
sourceimpl<T, S, A> BitAnd<&'_ HashSet<T, S, A>> for &HashSet<T, S, A> where
T: Eq + Hash + Clone,
S: BuildHasher + Default,
A: Allocator + Clone,
impl<T, S, A> BitAnd<&'_ HashSet<T, S, A>> for &HashSet<T, S, A> where
T: Eq + Hash + Clone,
S: BuildHasher + Default,
A: Allocator + Clone,
sourcefn bitand(self, rhs: &HashSet<T, S, A>) -> HashSet<T, S>
fn bitand(self, rhs: &HashSet<T, S, A>) -> HashSet<T, S>
Returns the intersection of self
and rhs
as a new HashSet<T, S>
.
Examples
use hashbrown::HashSet;
let a: HashSet<_> = vec![1, 2, 3].into_iter().collect();
let b: HashSet<_> = vec![2, 3, 4].into_iter().collect();
let set = &a & &b;
let mut i = 0;
let expected = [2, 3];
for x in &set {
assert!(expected.contains(x));
i += 1;
}
assert_eq!(i, expected.len());
sourceimpl<T, S, A> BitOr<&'_ HashSet<T, S, A>> for &HashSet<T, S, A> where
T: Eq + Hash + Clone,
S: BuildHasher + Default,
A: Allocator + Clone,
impl<T, S, A> BitOr<&'_ HashSet<T, S, A>> for &HashSet<T, S, A> where
T: Eq + Hash + Clone,
S: BuildHasher + Default,
A: Allocator + Clone,
sourcefn bitor(self, rhs: &HashSet<T, S, A>) -> HashSet<T, S>
fn bitor(self, rhs: &HashSet<T, S, A>) -> HashSet<T, S>
Returns the union of self
and rhs
as a new HashSet<T, S>
.
Examples
use hashbrown::HashSet;
let a: HashSet<_> = vec![1, 2, 3].into_iter().collect();
let b: HashSet<_> = vec![3, 4, 5].into_iter().collect();
let set = &a | &b;
let mut i = 0;
let expected = [1, 2, 3, 4, 5];
for x in &set {
assert!(expected.contains(x));
i += 1;
}
assert_eq!(i, expected.len());
sourceimpl<T, S> BitXor<&'_ HashSet<T, S, Global>> for &HashSet<T, S> where
T: Eq + Hash + Clone,
S: BuildHasher + Default,
impl<T, S> BitXor<&'_ HashSet<T, S, Global>> for &HashSet<T, S> where
T: Eq + Hash + Clone,
S: BuildHasher + Default,
sourcefn bitxor(self, rhs: &HashSet<T, S>) -> HashSet<T, S>
fn bitxor(self, rhs: &HashSet<T, S>) -> HashSet<T, S>
Returns the symmetric difference of self
and rhs
as a new HashSet<T, S>
.
Examples
use hashbrown::HashSet;
let a: HashSet<_> = vec![1, 2, 3].into_iter().collect();
let b: HashSet<_> = vec![3, 4, 5].into_iter().collect();
let set = &a ^ &b;
let mut i = 0;
let expected = [1, 2, 4, 5];
for x in &set {
assert!(expected.contains(x));
i += 1;
}
assert_eq!(i, expected.len());
sourceimpl<'a, T, S, A> Extend<&'a T> for HashSet<T, S, A> where
T: 'a + Eq + Hash + Copy,
S: BuildHasher,
A: Allocator + Clone,
impl<'a, T, S, A> Extend<&'a T> for HashSet<T, S, A> where
T: 'a + Eq + Hash + Copy,
S: BuildHasher,
A: Allocator + Clone,
sourcefn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I)
fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I)
Extends a collection with the contents of an iterator. Read more
sourcefn extend_one(&mut self, item: A)
fn extend_one(&mut self, item: A)
extend_one
)Extends a collection with exactly one element.
sourcefn extend_reserve(&mut self, additional: usize)
fn extend_reserve(&mut self, additional: usize)
extend_one
)Reserves capacity in a collection for the given number of additional elements. Read more
sourceimpl<T, S, A> Extend<T> for HashSet<T, S, A> where
T: Eq + Hash,
S: BuildHasher,
A: Allocator + Clone,
impl<T, S, A> Extend<T> for HashSet<T, S, A> where
T: Eq + Hash,
S: BuildHasher,
A: Allocator + Clone,
sourcefn extend<I: IntoIterator<Item = T>>(&mut self, iter: I)
fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I)
Extends a collection with the contents of an iterator. Read more
sourcefn extend_one(&mut self, item: A)
fn extend_one(&mut self, item: A)
extend_one
)Extends a collection with exactly one element.
sourcefn extend_reserve(&mut self, additional: usize)
fn extend_reserve(&mut self, additional: usize)
extend_one
)Reserves capacity in a collection for the given number of additional elements. Read more
sourceimpl<T, A, const N: usize> From<[T; N]> for HashSet<T, DefaultHashBuilder, A> where
T: Eq + Hash,
A: Default + Allocator + Clone,
impl<T, A, const N: usize> From<[T; N]> for HashSet<T, DefaultHashBuilder, A> where
T: Eq + Hash,
A: Default + Allocator + Clone,
sourceimpl<T, S, A> FromIterator<T> for HashSet<T, S, A> where
T: Eq + Hash,
S: BuildHasher + Default,
A: Default + Allocator + Clone,
impl<T, S, A> FromIterator<T> for HashSet<T, S, A> where
T: Eq + Hash,
S: BuildHasher + Default,
A: Default + Allocator + Clone,
sourcefn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Self
fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Self
Creates a value from an iterator. Read more
sourceimpl<'a, T, S, A: Allocator + Clone> IntoIterator for &'a HashSet<T, S, A>
impl<'a, T, S, A: Allocator + Clone> IntoIterator for &'a HashSet<T, S, A>
sourceimpl<T, S, A: Allocator + Clone> IntoIterator for HashSet<T, S, A>
impl<T, S, A: Allocator + Clone> IntoIterator for HashSet<T, S, A>
sourcefn into_iter(self) -> IntoIter<T, A>ⓘNotable traits for IntoIter<K, A>impl<K, A: Allocator + Clone> Iterator for IntoIter<K, A> type Item = K;
fn into_iter(self) -> IntoIter<T, A>ⓘNotable traits for IntoIter<K, A>impl<K, A: Allocator + Clone> Iterator for IntoIter<K, A> type Item = K;
Creates a consuming iterator, that is, one that moves each value out of the set in arbitrary order. The set cannot be used after calling this.
Examples
use hashbrown::HashSet;
let mut set = HashSet::new();
set.insert("a".to_string());
set.insert("b".to_string());
// Not possible to collect to a Vec<String> with a regular `.iter()`.
let v: Vec<String> = set.into_iter().collect();
// Will print in an arbitrary order.
for x in &v {
println!("{}", x);
}
type Item = T
type Item = T
The type of the elements being iterated over.
sourceimpl<T, S, A> PartialEq<HashSet<T, S, A>> for HashSet<T, S, A> where
T: Eq + Hash,
S: BuildHasher,
A: Allocator + Clone,
impl<T, S, A> PartialEq<HashSet<T, S, A>> for HashSet<T, S, A> where
T: Eq + Hash,
S: BuildHasher,
A: Allocator + Clone,
sourceimpl<T, S> Sub<&'_ HashSet<T, S, Global>> for &HashSet<T, S> where
T: Eq + Hash + Clone,
S: BuildHasher + Default,
impl<T, S> Sub<&'_ HashSet<T, S, Global>> for &HashSet<T, S> where
T: Eq + Hash + Clone,
S: BuildHasher + Default,
sourcefn sub(self, rhs: &HashSet<T, S>) -> HashSet<T, S>
fn sub(self, rhs: &HashSet<T, S>) -> HashSet<T, S>
Returns the difference of self
and rhs
as a new HashSet<T, S>
.
Examples
use hashbrown::HashSet;
let a: HashSet<_> = vec![1, 2, 3].into_iter().collect();
let b: HashSet<_> = vec![3, 4, 5].into_iter().collect();
let set = &a - &b;
let mut i = 0;
let expected = [1, 2];
for x in &set {
assert!(expected.contains(x));
i += 1;
}
assert_eq!(i, expected.len());
impl<T, S, A> Eq for HashSet<T, S, A> where
T: Eq + Hash,
S: BuildHasher,
A: Allocator + Clone,
Auto Trait Implementations
impl<T, S, A> RefUnwindSafe for HashSet<T, S, A> where
A: RefUnwindSafe,
S: RefUnwindSafe,
T: RefUnwindSafe,
impl<T, S, A> Send for HashSet<T, S, A> where
A: Send,
S: Send,
T: Send,
impl<T, S, A> Sync for HashSet<T, S, A> where
A: Sync,
S: Sync,
T: Sync,
impl<T, S, A> Unpin for HashSet<T, S, A> where
A: Unpin,
S: Unpin,
T: Unpin,
impl<T, S, A> UnwindSafe for HashSet<T, S, A> where
A: UnwindSafe,
S: UnwindSafe,
T: UnwindSafe,
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcepub fn borrow_mut(&mut self) -> &mut T
pub fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
sourceimpl<T> ToOwned for T where
T: Clone,
impl<T> ToOwned for T where
T: Clone,
type Owned = T
type Owned = T
The resulting type after obtaining ownership.
sourcepub fn to_owned(&self) -> T
pub fn to_owned(&self) -> T
Creates owned data from borrowed data, usually by cloning. Read more
sourcepub fn clone_into(&self, target: &mut T)
pub fn clone_into(&self, target: &mut T)
toowned_clone_into
)Uses borrowed data to replace owned data, usually by cloning. Read more