pub struct HashSet<T, S = DefaultHashBuilder, A: Allocator = 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" ].into_iter().collect();
// use the values stored in the set
Implementations§
source§impl<T, S, A> HashSet<T, S, A>
impl<T, S, A> HashSet<T, S, A>
sourcepub fn par_union<'a>(&'a self, other: &'a Self) -> ParUnion<'a, T, S, A>
pub fn par_union<'a>(&'a self, other: &'a Self) -> ParUnion<'a, T, S, A>
Visits (potentially in parallel) the values representing the union,
i.e. all the values in self
or other
, without duplicates.
sourcepub fn par_difference<'a>(
&'a self,
other: &'a Self,
) -> ParDifference<'a, T, S, A>
pub fn par_difference<'a>( &'a self, other: &'a Self, ) -> ParDifference<'a, T, S, A>
Visits (potentially in parallel) the values representing the difference,
i.e. the values that are in self
but not in other
.
sourcepub fn par_symmetric_difference<'a>(
&'a self,
other: &'a Self,
) -> ParSymmetricDifference<'a, T, S, A>
pub fn par_symmetric_difference<'a>( &'a self, other: &'a Self, ) -> ParSymmetricDifference<'a, T, S, A>
Visits (potentially in parallel) the values representing the symmetric
difference, i.e. the values that are in self
or in other
but not in both.
sourcepub fn par_intersection<'a>(
&'a self,
other: &'a Self,
) -> ParIntersection<'a, T, S, A>
pub fn par_intersection<'a>( &'a self, other: &'a Self, ) -> ParIntersection<'a, T, S, A>
Visits (potentially in parallel) the values representing the
intersection, i.e. the values that are both in self
and other
.
sourcepub fn par_is_disjoint(&self, other: &Self) -> bool
pub fn par_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.
This method runs in a potentially parallel fashion.
sourcepub fn par_is_subset(&self, other: &Self) -> bool
pub fn par_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
.
This method runs in a potentially parallel fashion.
sourcepub fn par_is_superset(&self, other: &Self) -> bool
pub fn par_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
.
This method runs in a potentially parallel fashion.
source§impl<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.
§HashDoS resistance
The hash_builder
normally use a fixed key by default and that does
not allow the HashSet
to be protected against attacks such as HashDoS
.
Users who require HashDoS resistance should explicitly use
std::collections::hash_map::RandomState
as the hasher when creating a HashSet
, for example with
with_hasher
method.
§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.
§HashDoS resistance
The hash_builder
normally use a fixed key by default and that does
not allow the HashSet
to be protected against attacks such as HashDoS
.
Users who require HashDoS resistance should explicitly use
std::collections::hash_map::RandomState
as the hasher when creating a HashSet
, for example with
with_capacity_and_hasher
method.
§Examples
use hashbrown::HashSet;
let set: HashSet<i32> = HashSet::with_capacity(10);
assert!(set.capacity() >= 10);
source§impl<T: Hash + Eq, A: Allocator> HashSet<T, DefaultHashBuilder, A>
impl<T: Hash + Eq, A: Allocator> 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.
§HashDoS resistance
The hash_builder
normally use a fixed key by default and that does
not allow the HashSet
to be protected against attacks such as HashDoS
.
Users who require HashDoS resistance should explicitly use
std::collections::hash_map::RandomState
as the hasher when creating a HashSet
, for example with
with_hasher_in
method.
§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.
§HashDoS resistance
The hash_builder
normally use a fixed key by default and that does
not allow the HashSet
to be protected against attacks such as HashDoS
.
Users who require HashDoS resistance should explicitly use
std::collections::hash_map::RandomState
as the hasher when creating a HashSet
, for example with
with_capacity_and_hasher_in
method.
§Examples
use hashbrown::HashSet;
let set: HashSet<i32> = HashSet::with_capacity(10);
assert!(set.capacity() >= 10);
source§impl<T, S, A: Allocator> HashSet<T, S, A>
impl<T, S, A: Allocator> 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> ⓘ
pub fn iter(&self) -> Iter<'_, T> ⓘ
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> ⓘ
pub fn drain(&mut self) -> Drain<'_, T, A> ⓘ
Clears the set, returning all elements in an iterator.
§Examples
use hashbrown::HashSet;
let mut set: HashSet<_> = [1, 2, 3].into_iter().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)
pub fn retain<F>(&mut self, f: F)
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.into_iter().collect();
set.retain(|&k| k % 2 == 0);
assert_eq!(set.len(), 3);
sourcepub fn extract_if<F>(&mut self, f: F) -> ExtractIf<'_, T, F, A> ⓘ
pub fn extract_if<F>(&mut self, f: F) -> ExtractIf<'_, T, F, A> ⓘ
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.
If the returned ExtractIf
is not exhausted, e.g. because it is dropped without iterating
or the iteration short-circuits, then the remaining elements will be retained.
Use retain()
with a negated predicate if you do not need the returned iterator.
§Examples
use hashbrown::HashSet;
let mut set: HashSet<i32> = (0..8).collect();
let drained: HashSet<i32> = set.extract_if(|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]);
source§impl<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 initially created with a capacity of 0, so it will not allocate until it is first inserted into.
§HashDoS resistance
The hash_builder
normally use a fixed key by default and that does
not allow the HashSet
to be protected against attacks such as HashDoS
.
Users who require HashDoS resistance should explicitly use
std::collections::hash_map::RandomState
as the hasher when creating a HashSet
.
The hash_builder
passed should implement the BuildHasher
trait for
the HashSet
to be useful, see its documentation for details.
§Examples
use hashbrown::HashSet;
use hashbrown::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.
§HashDoS resistance
The hash_builder
normally use a fixed key by default and that does
not allow the HashSet
to be protected against attacks such as HashDoS
.
Users who require HashDoS resistance should explicitly use
std::collections::hash_map::RandomState
as the hasher when creating a HashSet
.
The hash_builder
passed should implement the BuildHasher
trait for
the HashSet
to be useful, see its documentation for details.
§Examples
use hashbrown::HashSet;
use hashbrown::DefaultHashBuilder;
let s = DefaultHashBuilder::default();
let mut set = HashSet::with_capacity_and_hasher(10, s);
set.insert(1);
source§impl<T, S, A> HashSet<T, S, A>where
A: Allocator,
impl<T, S, A> HashSet<T, S, A>where
A: Allocator,
sourcepub const fn with_hasher_in(hasher: S, alloc: A) -> Self
pub const 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 initially created with a capacity of 0, so it will not allocate until it is first inserted into.
§HashDoS resistance
The hash_builder
normally use a fixed key by default and that does
not allow the HashSet
to be protected against attacks such as HashDoS
.
Users who require HashDoS resistance should explicitly use
std::collections::hash_map::RandomState
as the hasher when creating a HashSet
.
The hash_builder
passed should implement the BuildHasher
trait for
the HashSet
to be useful, see its documentation for details.
§Examples
use hashbrown::HashSet;
use hashbrown::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.
§HashDoS resistance
The hash_builder
normally use a fixed key by default and that does
not allow the HashSet
to be protected against attacks such as HashDoS
.
Users who require HashDoS resistance should explicitly use
std::collections::hash_map::RandomState
as the hasher when creating a HashSet
.
The hash_builder
passed should implement the BuildHasher
trait for
the HashSet
to be useful, see its documentation for details.
§Examples
use hashbrown::HashSet;
use hashbrown::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::DefaultHashBuilder;
let hasher = DefaultHashBuilder::default();
let set: HashSet<i32> = HashSet::with_hasher(hasher);
let hasher: &DefaultHashBuilder = set.hasher();
source§impl<T, S, A> HashSet<T, S, A>
impl<T, S, A> HashSet<T, S, A>
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 capacity exceeds isize::MAX
bytes and abort
the program
in case of allocation error. Use try_reserve
instead
if you want to handle memory allocation failure.
§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> ⓘ
pub fn difference<'a>(&'a self, other: &'a Self) -> Difference<'a, T, S, A> ⓘ
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].into_iter().collect();
let b: HashSet<_> = [4, 2, 3, 4].into_iter().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> ⓘ
pub fn symmetric_difference<'a>( &'a self, other: &'a Self, ) -> SymmetricDifference<'a, T, S, A> ⓘ
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].into_iter().collect();
let b: HashSet<_> = [4, 2, 3, 4].into_iter().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> ⓘ
pub fn intersection<'a>(&'a self, other: &'a Self) -> Intersection<'a, T, S, A> ⓘ
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].into_iter().collect();
let b: HashSet<_> = [4, 2, 3, 4].into_iter().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> ⓘ
pub fn union<'a>(&'a self, other: &'a Self) -> Union<'a, T, S, A> ⓘ
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].into_iter().collect();
let b: HashSet<_> = [4, 2, 3, 4].into_iter().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>(&self, value: &Q) -> bool
pub fn contains<Q>(&self, value: &Q) -> bool
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].into_iter().collect();
assert_eq!(set.contains(&1), true);
assert_eq!(set.contains(&4), false);
sourcepub fn get<Q>(&self, value: &Q) -> Option<&T>
pub fn get<Q>(&self, value: &Q) -> Option<&T>
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].into_iter().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].into_iter().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_with<Q, F>(&mut self, value: &Q, f: F) -> &T
pub fn get_or_insert_with<Q, F>(&mut self, value: &Q, f: F) -> &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
The following example will panic because the new value doesn’t match.
let mut set = hashbrown::HashSet::new();
set.get_or_insert_with("rust", |_| String::new());
sourcepub fn entry(&mut self, value: T) -> Entry<'_, T, S, A>
pub fn entry(&mut self, value: T) -> Entry<'_, T, S, A>
Gets the given value’s corresponding entry in the set for in-place manipulation.
§Examples
use hashbrown::HashSet;
use hashbrown::hash_set::Entry::*;
let mut singles = HashSet::new();
let mut dupes = HashSet::new();
for ch in "a short treatise on fungi".chars() {
if let Vacant(dupe_entry) = dupes.entry(ch) {
// We haven't already seen a duplicate, so
// check if we've at least seen it once.
match singles.entry(ch) {
Vacant(single_entry) => {
// We found a new character for the first time.
single_entry.insert();
}
Occupied(single_entry) => {
// We've already seen this once, "move" it to dupes.
single_entry.remove();
dupe_entry.insert();
}
}
}
}
assert!(!singles.contains(&'t') && dupes.contains(&'t'));
assert!(singles.contains(&'u') && !dupes.contains(&'u'));
assert!(!singles.contains(&'v') && !dupes.contains(&'v'));
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].into_iter().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].into_iter().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].into_iter().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 unsafe fn insert_unique_unchecked(&mut self, value: T) -> &T
pub unsafe fn insert_unique_unchecked(&mut self, value: T) -> &T
Insert a value the set without checking if the value already exists in the set.
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.
§Safety
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.
However this operation is still unsafe because the resulting HashSet
may be passed to unsafe code which does expect the set to behave
correctly, and would cause unsoundness as a result.
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>(&mut self, value: &Q) -> bool
pub fn remove<Q>(&mut self, value: &Q) -> bool
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>(&mut self, value: &Q) -> Option<T>
pub fn take<Q>(&mut self, value: &Q) -> Option<T>
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].into_iter().collect();
assert_eq!(set.take(&2), Some(2));
assert_eq!(set.take(&2), None);
sourcepub fn allocation_size(&self) -> usize
pub fn allocation_size(&self) -> usize
Returns the total amount of memory allocated internally by the hash set, in bytes.
The returned number is informational only. It is intended to be primarily used for memory profiling.
Trait Implementations§
source§impl<T, S, A> BitAnd<&HashSet<T, S, A>> for &HashSet<T, S, A>
impl<T, S, A> BitAnd<&HashSet<T, S, A>> for &HashSet<T, S, A>
source§fn bitand(self, rhs: &HashSet<T, S, A>) -> HashSet<T, S, A>
fn bitand(self, rhs: &HashSet<T, S, A>) -> HashSet<T, S, A>
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());
source§impl<T, S, A> BitAndAssign<&HashSet<T, S, A>> for HashSet<T, S, A>
impl<T, S, A> BitAndAssign<&HashSet<T, S, A>> for HashSet<T, S, A>
source§fn bitand_assign(&mut self, rhs: &HashSet<T, S, A>)
fn bitand_assign(&mut self, rhs: &HashSet<T, S, A>)
Modifies this set to contain the intersection of self
and rhs
.
§Examples
use hashbrown::HashSet;
let mut a: HashSet<_> = vec![1, 2, 3].into_iter().collect();
let b: HashSet<_> = vec![2, 3, 4].into_iter().collect();
a &= &b;
let mut i = 0;
let expected = [2, 3];
for x in &a {
assert!(expected.contains(x));
i += 1;
}
assert_eq!(i, expected.len());
source§impl<T, S, A> BitOr<&HashSet<T, S, A>> for &HashSet<T, S, A>
impl<T, S, A> BitOr<&HashSet<T, S, A>> for &HashSet<T, S, A>
source§fn bitor(self, rhs: &HashSet<T, S, A>) -> HashSet<T, S, A>
fn bitor(self, rhs: &HashSet<T, S, A>) -> HashSet<T, S, A>
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());
source§impl<T, S, A> BitOrAssign<&HashSet<T, S, A>> for HashSet<T, S, A>
impl<T, S, A> BitOrAssign<&HashSet<T, S, A>> for HashSet<T, S, A>
source§fn bitor_assign(&mut self, rhs: &HashSet<T, S, A>)
fn bitor_assign(&mut self, rhs: &HashSet<T, S, A>)
Modifies this set to contain the union of self
and rhs
.
§Examples
use hashbrown::HashSet;
let mut a: HashSet<_> = vec![1, 2, 3].into_iter().collect();
let b: HashSet<_> = vec![3, 4, 5].into_iter().collect();
a |= &b;
let mut i = 0;
let expected = [1, 2, 3, 4, 5];
for x in &a {
assert!(expected.contains(x));
i += 1;
}
assert_eq!(i, expected.len());
source§impl<T, S, A> BitXor<&HashSet<T, S, A>> for &HashSet<T, S, A>
impl<T, S, A> BitXor<&HashSet<T, S, A>> for &HashSet<T, S, A>
source§fn bitxor(self, rhs: &HashSet<T, S, A>) -> HashSet<T, S, A>
fn bitxor(self, rhs: &HashSet<T, S, A>) -> HashSet<T, S, A>
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());
source§impl<T, S, A> BitXorAssign<&HashSet<T, S, A>> for HashSet<T, S, A>
impl<T, S, A> BitXorAssign<&HashSet<T, S, A>> for HashSet<T, S, A>
source§fn bitxor_assign(&mut self, rhs: &HashSet<T, S, A>)
fn bitxor_assign(&mut self, rhs: &HashSet<T, S, A>)
Modifies this set to contain the symmetric difference of self
and rhs
.
§Examples
use hashbrown::HashSet;
let mut a: HashSet<_> = vec![1, 2, 3].into_iter().collect();
let b: HashSet<_> = vec![3, 4, 5].into_iter().collect();
a ^= &b;
let mut i = 0;
let expected = [1, 2, 4, 5];
for x in &a {
assert!(expected.contains(x));
i += 1;
}
assert_eq!(i, expected.len());
source§impl<'de, T, S, A> Deserialize<'de> for HashSet<T, S, A>
impl<'de, T, S, A> Deserialize<'de> for HashSet<T, S, A>
source§fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>where
D: Deserializer<'de>,
fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>where
D: Deserializer<'de>,
source§impl<'a, T, S, A> Extend<&'a T> for HashSet<T, S, A>
impl<'a, T, S, A> Extend<&'a T> for HashSet<T, S, A>
source§fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I)
fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I)
source§fn extend_one(&mut self, k: &'a T)
fn extend_one(&mut self, k: &'a T)
extend_one
)source§fn extend_reserve(&mut self, additional: usize)
fn extend_reserve(&mut self, additional: usize)
extend_one
)source§impl<T, S, A> Extend<T> for HashSet<T, S, A>
impl<T, S, A> Extend<T> for HashSet<T, S, A>
source§fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I)
fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I)
source§fn extend_one(&mut self, k: T)
fn extend_one(&mut self, k: T)
extend_one
)source§fn extend_reserve(&mut self, additional: usize)
fn extend_reserve(&mut self, additional: usize)
extend_one
)source§impl<T, S, A> FromIterator<T> for HashSet<T, S, A>
impl<T, S, A> FromIterator<T> for HashSet<T, S, A>
source§fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Self
fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Self
source§impl<T, S> FromParallelIterator<T> for HashSet<T, S, Global>
impl<T, S> FromParallelIterator<T> for HashSet<T, S, Global>
Collect values from a parallel iterator into a hashset.
source§fn from_par_iter<P>(par_iter: P) -> Selfwhere
P: IntoParallelIterator<Item = T>,
fn from_par_iter<P>(par_iter: P) -> Selfwhere
P: IntoParallelIterator<Item = T>,
par_iter
. Read moresource§impl<'a, T, S, A: Allocator> IntoIterator for &'a HashSet<T, S, A>
impl<'a, T, S, A: Allocator> IntoIterator for &'a HashSet<T, S, A>
source§impl<T, S, A: Allocator> IntoIterator for HashSet<T, S, A>
impl<T, S, A: Allocator> IntoIterator for HashSet<T, S, A>
source§fn into_iter(self) -> IntoIter<T, A> ⓘ
fn into_iter(self) -> IntoIter<T, A> ⓘ
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);
}
source§impl<'a, T, S> ParallelExtend<&'a T> for HashSet<T, S, Global>
impl<'a, T, S> ParallelExtend<&'a T> for HashSet<T, S, Global>
Extend a hash set with copied items from a parallel iterator.
source§fn par_extend<I>(&mut self, par_iter: I)where
I: IntoParallelIterator<Item = &'a T>,
fn par_extend<I>(&mut self, par_iter: I)where
I: IntoParallelIterator<Item = &'a T>,
par_iter
. Read moresource§impl<T, S> ParallelExtend<T> for HashSet<T, S, Global>
impl<T, S> ParallelExtend<T> for HashSet<T, S, Global>
Extend a hash set with items from a parallel iterator.
source§fn par_extend<I>(&mut self, par_iter: I)where
I: IntoParallelIterator<Item = T>,
fn par_extend<I>(&mut self, par_iter: I)where
I: IntoParallelIterator<Item = T>,
par_iter
. Read moresource§impl<T, S, A> Sub<&HashSet<T, S, A>> for &HashSet<T, S, A>
impl<T, S, A> Sub<&HashSet<T, S, A>> for &HashSet<T, S, A>
source§fn sub(self, rhs: &HashSet<T, S, A>) -> HashSet<T, S, A>
fn sub(self, rhs: &HashSet<T, S, A>) -> HashSet<T, S, A>
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());
source§impl<T, S, A> SubAssign<&HashSet<T, S, A>> for HashSet<T, S, A>
impl<T, S, A> SubAssign<&HashSet<T, S, A>> for HashSet<T, S, A>
source§fn sub_assign(&mut self, rhs: &HashSet<T, S, A>)
fn sub_assign(&mut self, rhs: &HashSet<T, S, A>)
Modifies this set to contain the difference of self
and rhs
.
§Examples
use hashbrown::HashSet;
let mut a: HashSet<_> = vec![1, 2, 3].into_iter().collect();
let b: HashSet<_> = vec![3, 4, 5].into_iter().collect();
a -= &b;
let mut i = 0;
let expected = [1, 2];
for x in &a {
assert!(expected.contains(x));
i += 1;
}
assert_eq!(i, expected.len());
impl<T, S, A> Eq for HashSet<T, S, A>
Auto Trait Implementations§
impl<T, S, A> Freeze for HashSet<T, S, A>
impl<T, S, A> RefUnwindSafe for HashSet<T, S, A>
impl<T, S, A> Send for HashSet<T, S, A>
impl<T, S, A> Sync for HashSet<T, S, A>
impl<T, S, A> Unpin for HashSet<T, S, A>
impl<T, S, A> UnwindSafe for HashSet<T, S, A>
Blanket Implementations§
source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
source§impl<T> CloneToUninit for Twhere
T: Clone,
impl<T> CloneToUninit for Twhere
T: Clone,
source§unsafe fn clone_to_uninit(&self, dst: *mut T)
unsafe fn clone_to_uninit(&self, dst: *mut T)
clone_to_uninit
)source§impl<Q, K> Equivalent<K> for Q
impl<Q, K> Equivalent<K> for Q
source§fn equivalent(&self, key: &K) -> bool
fn equivalent(&self, key: &K) -> bool
key
and return true
if they are equal.source§impl<T> IntoEither for T
impl<T> IntoEither for T
source§fn into_either(self, into_left: bool) -> Either<Self, Self>
fn into_either(self, into_left: bool) -> Either<Self, Self>
self
into a Left
variant of Either<Self, Self>
if into_left
is true
.
Converts self
into a Right
variant of Either<Self, Self>
otherwise. Read moresource§fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
self
into a Left
variant of Either<Self, Self>
if into_left(&self)
returns true
.
Converts self
into a Right
variant of Either<Self, Self>
otherwise. Read more