Struct HashSet

pub struct HashSet<T, S = FixedHasher>(/* private fields */);

New-type for HashSet with FixedHasher as the default hashing provider. Can be trivially converted to and from a hashbrown HashSet using From.

A new-type is used instead of a type alias due to critical methods like new being incompatible with Bevy’s choice of default hasher.

Implementations

impl<T> HashSet<T>

pub const fn new() -> HashSet<T>

Creates an empty HashSet.

Refer to new for further details.

Examples

// Creates a HashSet with zero capacity.
let map = HashSet::new();

pub fn with_capacity(capacity: usize) -> HashSet<T>

Creates an empty HashSet with the specified capacity.

Refer to with_capacity for further details.

Examples

// Creates a HashSet with capacity for at least 5 entries.
let map = HashSet::with_capacity(5);

impl<T, S> HashSet<T, S>

pub fn capacity(&self) -> usize

Returns the number of elements the set can hold without reallocating.

Refer to capacity for further details.

Examples

let map = HashSet::with_capacity(5);

assert!(map.capacity() >= 5);

pub fn iter(&self) -> Iter<'_, T>

An iterator visiting all elements in arbitrary order. The iterator element type is &'a T.

Refer to iter for further details.

Examples

let mut map = HashSet::new();

map.insert("foo");
map.insert("bar");
map.insert("baz");

for value in map.iter() {
    // "foo", "bar", "baz"
    // Note that the above order is not guaranteed
}

pub fn len(&self) -> usize

Returns the number of elements in the set.

Refer to len for further details.

Examples

let mut map = HashSet::new();

assert_eq!(map.len(), 0);

map.insert("foo");

assert_eq!(map.len(), 1);

pub fn is_empty(&self) -> bool

Returns true if the set contains no elements.

Refer to is_empty for further details.

Examples

let mut map = HashSet::new();

assert!(map.is_empty());

map.insert("foo");

assert!(!map.is_empty());

pub fn drain(&mut self) -> Drain<'_, T>

Clears the set, returning all elements in an iterator.

Refer to drain for further details.

Examples

let mut map = HashSet::new();

map.insert("foo");
map.insert("bar");
map.insert("baz");

for value in map.drain() {
    // "foo", "bar", "baz"
    // Note that the above order is not guaranteed
}

assert!(map.is_empty());

pub fn retain<F>(&mut self, f: F)

where F: FnMut(&T) -> bool,

Retains only the elements specified by the predicate.

Refer to retain for further details.

Examples

let mut map = HashSet::new();

map.insert("foo");
map.insert("bar");
map.insert("baz");

map.retain(|value| *value == "baz");

assert_eq!(map.len(), 1);

pub fn extract_if<F>(&mut self, f: F) -> ExtractIf<'_, T, F>

where F: FnMut(&T) -> bool,

Drains elements which are true under the given predicate, and returns an iterator over the removed items.

Refer to extract_if for further details.

Examples

let mut map = HashSet::new();

map.insert("foo");
map.insert("bar");
map.insert("baz");

let extracted = map
    .extract_if(|value| *value == "baz")
    .collect::<Vec<_>>();

assert_eq!(map.len(), 2);
assert_eq!(extracted.len(), 1);

pub fn clear(&mut self)

Clears the set, removing all values.

Refer to clear for further details.

Examples

let mut map = HashSet::new();

map.insert("foo");
map.insert("bar");
map.insert("baz");

map.clear();

assert!(map.is_empty());

pub const fn with_hasher(hasher: S) -> HashSet<T, S>

Creates a new empty hash set which will use the given hasher to hash keys.

Refer to with_hasher for further details.

Examples

// Creates a HashSet with the provided hasher.
let map = HashSet::with_hasher(SomeHasher);

pub fn with_capacity_and_hasher(capacity: usize, hasher: S) -> HashSet<T, S>

Creates an empty HashSet with the specified capacity, using hasher to hash the keys.

Refer to with_capacity_and_hasher for further details.

Examples

// Creates a HashSet with capacity for 5 entries and the provided hasher.
let map = HashSet::with_capacity_and_hasher(5, SomeHasher);

pub fn hasher(&self) -> &S

Returns a reference to the set’s BuildHasher.

Refer to hasher for further details.

pub fn into_inner(self) -> HashSet<T, S>

Takes the inner HashSet out of this wrapper.

Examples

let map: HashSet<&'static str> = HashSet::new();
let map: hashbrown::HashSet<&'static str, _> = map.into_inner();

impl<T, S> HashSet<T, S>

where T: Eq + Hash, S: BuildHasher,

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.

Refer to reserve for further details.

Examples

let mut map = HashSet::with_capacity(5);

assert!(map.capacity() >= 5);

map.reserve(10);

assert!(map.capacity() - map.len() >= 10);

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.

Refer to try_reserve for further details.

Examples

let mut map = HashSet::with_capacity(5);

assert!(map.capacity() >= 5);

map.try_reserve(10).expect("Out of Memory!");

assert!(map.capacity() - map.len() >= 10);

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.

Refer to shrink_to_fit for further details.

Examples

let mut map = HashSet::with_capacity(5);

map.insert("foo");
map.insert("bar");
map.insert("baz");

assert!(map.capacity() >= 5);

map.shrink_to_fit();

assert_eq!(map.capacity(), 3);

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.

Refer to shrink_to for further details.

pub fn difference<'a>( &'a self, other: &'a HashSet<T, S>, ) -> Difference<'a, T, S>

Visits the values representing the difference, i.e., the values that are in self but not in other.

Refer to difference for further details.

pub fn symmetric_difference<'a>( &'a self, other: &'a HashSet<T, S>, ) -> SymmetricDifference<'a, T, S>

Visits the values representing the symmetric difference, i.e., the values that are in self or in other but not in both.

Refer to symmetric_difference for further details.

pub fn intersection<'a>( &'a self, other: &'a HashSet<T, S>, ) -> Intersection<'a, T, S>

Visits the values representing the intersection, i.e., the values that are both in self and other.

Refer to intersection for further details.

pub fn union<'a>(&'a self, other: &'a HashSet<T, S>) -> Union<'a, T, S>

Visits the values representing the union, i.e., all the values in self or other, without duplicates.

Refer to union for further details.

pub fn contains<Q>(&self, value: &Q) -> bool

where Q: Hash + Equivalent<T> + ?Sized,

Returns true if the set contains a value.

Refer to contains for further details.

Examples

let mut map = HashSet::new();

map.insert("foo");

assert!(map.contains("foo"));

pub fn get<Q>(&self, value: &Q) -> Option<&T>

where Q: Hash + Equivalent<T> + ?Sized,

Returns a reference to the value in the set, if any, that is equal to the given value.

Refer to get for further details.

Examples

let mut map = HashSet::new();

map.insert("foo");

assert_eq!(map.get("foo"), Some(&"foo"));

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.

Refer to get_or_insert for further details.

Examples

let mut map = HashSet::new();

assert_eq!(map.get_or_insert("foo"), &"foo");

pub fn get_or_insert_with<Q, F>(&mut self, value: &Q, f: F) -> &T

where Q: Hash + Equivalent<T> + ?Sized, 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.

Refer to get_or_insert_with for further details.

Examples

let mut map = HashSet::new();

assert_eq!(map.get_or_insert_with(&"foo", |_| "foo"), &"foo");

pub fn entry(&mut self, value: T) -> Entry<'_, T, S>

Gets the given value’s corresponding entry in the set for in-place manipulation.

Refer to entry for further details.

Examples

let mut map = HashSet::new();

let value = map.entry("foo").or_insert();

pub fn is_disjoint(&self, other: &HashSet<T, S>) -> bool

Returns true if self has no elements in common with other. This is equivalent to checking for an empty intersection.

Refer to is_disjoint for further details.

pub fn is_subset(&self, other: &HashSet<T, S>) -> bool

Returns true if the set is a subset of another, i.e., other contains at least all the values in self.

Refer to is_subset for further details.

pub fn is_superset(&self, other: &HashSet<T, S>) -> bool

Returns true if the set is a superset of another, i.e., self contains at least all the values in other.

Refer to is_superset for further details.

pub fn insert(&mut self, value: T) -> bool

Adds a value to the set.

Refer to insert for further details.

Examples

let mut map = HashSet::new();

map.insert("foo");

assert!(map.contains("foo"));

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.

Refer to replace for further details.

Examples

let mut map = HashSet::new();

map.insert("foo");

assert_eq!(map.replace("foo"), Some("foo"));

pub fn remove<Q>(&mut self, value: &Q) -> bool

where Q: Hash + Equivalent<T> + ?Sized,

Removes a value from the set. Returns whether the value was present in the set.

Refer to remove for further details.

Examples

let mut map = HashSet::new();

map.insert("foo");

assert!(map.remove("foo"));

assert!(map.is_empty());

pub fn take<Q>(&mut self, value: &Q) -> Option<T>

where Q: Hash + Equivalent<T> + ?Sized,

Removes and returns the value in the set, if any, that is equal to the given one.

Refer to take for further details.

Examples

let mut map = HashSet::new();

map.insert("foo");

assert_eq!(map.take("foo"), Some("foo"));

assert!(map.is_empty());

pub fn allocation_size(&self) -> usize

Returns the total amount of memory allocated internally by the hash set, in bytes.

Refer to allocation_size for further details.

Examples

let mut map = HashSet::new();

assert_eq!(map.allocation_size(), 0);

map.insert("foo");

assert!(map.allocation_size() >= size_of::<&'static str>());

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.

Refer to insert_unique_unchecked for further details.

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.

Methods from Deref<Target = HashSet<T, S>>

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);

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);
}

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);

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());

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());

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.into_iter().collect();
set.retain(|&k| k % 2 == 0);
assert_eq!(set.len(), 3);

pub fn extract_if<F>(&mut self, f: F) -> ExtractIf<'_, T, F, A>

where F: FnMut(&T) -> bool,

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]);

pub fn clear(&mut self)

Clears the set, removing all values.

Examples

use hashbrown::HashSet;

let mut v = HashSet::new();
v.insert(1);
v.clear();
assert!(v.is_empty());

pub fn allocator(&self) -> &A

Returns a reference to the underlying allocator.

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();

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);

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?");

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);

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);

pub fn difference<'a>( &'a self, other: &'a HashSet<T, S, A>, ) -> 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());

pub fn symmetric_difference<'a>( &'a self, other: &'a HashSet<T, S, A>, ) -> 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());

pub fn intersection<'a>( &'a self, other: &'a HashSet<T, S, A>, ) -> 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());

pub fn union<'a>(&'a self, other: &'a HashSet<T, S, A>) -> 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());

pub fn contains<Q>(&self, value: &Q) -> bool

where Q: Hash + Equivalent<T> + ?Sized,

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);

pub fn get<Q>(&self, value: &Q) -> Option<&T>

where Q: Hash + Equivalent<T> + ?Sized,

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);

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

pub fn get_or_insert_with<Q, F>(&mut self, value: &Q, f: F) -> &T

where Q: Hash + Equivalent<T> + ?Sized, 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

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());

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'));

pub fn is_disjoint(&self, other: &HashSet<T, S, A>) -> 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);

pub fn is_subset(&self, other: &HashSet<T, S, A>) -> 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);

pub fn is_superset(&self, other: &HashSet<T, S, A>) -> 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);

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);

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.

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);

pub fn remove<Q>(&mut self, value: &Q) -> bool

where Q: Hash + Equivalent<T> + ?Sized,

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);

pub fn take<Q>(&mut self, value: &Q) -> Option<T>

where Q: Hash + Equivalent<T> + ?Sized,

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);

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

impl<T, S> BitAnd<&HashSet<T, S>> for &HashSet<T, S>

where &'a HashSet<T, S>: for<'a> BitAnd<Output = HashSet<T, S>>,

fn bitand(self, rhs: &HashSet<T, S>) -> HashSet<T, S>

Returns the intersection of self and rhs as a new HashSet<T, S>.

type Output = HashSet<T, S>

The resulting type after applying the & operator.

impl<T, S> BitAndAssign<&HashSet<T, S>> for HashSet<T, S>

where HashSet<T, S>: for<'a> BitAndAssign<&'a HashSet<T, S>>,

fn bitand_assign(&mut self, rhs: &HashSet<T, S>)

Modifies this set to contain the intersection of self and rhs.

impl<T, S> BitOr<&HashSet<T, S>> for &HashSet<T, S>

where &'a HashSet<T, S>: for<'a> BitOr<Output = HashSet<T, S>>,

fn bitor(self, rhs: &HashSet<T, S>) -> HashSet<T, S>

Returns the union of self and rhs as a new HashSet<T, S>.

type Output = HashSet<T, S>

The resulting type after applying the | operator.

impl<T, S> BitOrAssign<&HashSet<T, S>> for HashSet<T, S>

where HashSet<T, S>: for<'a> BitOrAssign<&'a HashSet<T, S>>,

fn bitor_assign(&mut self, rhs: &HashSet<T, S>)

Modifies this set to contain the union of self and rhs.

impl<T, S> BitXor<&HashSet<T, S>> for &HashSet<T, S>

where &'a HashSet<T, S>: for<'a> BitXor<Output = 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>.

type Output = HashSet<T, S>

The resulting type after applying the ^ operator.

impl<T, S> BitXorAssign<&HashSet<T, S>> for HashSet<T, S>

where HashSet<T, S>: for<'a> BitXorAssign<&'a HashSet<T, S>>,

fn bitxor_assign(&mut self, rhs: &HashSet<T, S>)

Modifies this set to contain the symmetric difference of self and rhs.

impl<T, S> Clone for HashSet<T, S>

where HashSet<T, S>: Clone,

fn clone(&self) -> HashSet<T, S>

Returns a copy of the value.

fn clone_from(&mut self, source: &HashSet<T, S>)

Performs copy-assignment from source.

impl<T, S> Debug for HashSet<T, S>

where HashSet<T, S>: Debug,

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<T, S> Default for HashSet<T, S>

where HashSet<T, S>: Default,

fn default() -> HashSet<T, S>

Returns the “default value” for a type.

impl<T, S> Deref for HashSet<T, S>

type Target = HashSet<T, S>

The resulting type after dereferencing.

fn deref(&self) -> &<HashSet<T, S> as Deref>::Target

Dereferences the value.

impl<T, S> DerefMut for HashSet<T, S>

fn deref_mut(&mut self) -> &mut <HashSet<T, S> as Deref>::Target

Mutably dereferences the value.

impl<'de, T, S> Deserialize<'de> for HashSet<T, S>

where HashSet<T, S>: Deserialize<'de>,

fn deserialize<D>( deserializer: D, ) -> Result<HashSet<T, S>, <D as Deserializer<'de>>::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl DynamicComponentFetch for &HashSet<ComponentId>

type Ref<'w> = HashMap<ComponentId, Ptr<'w>>

The read-only reference type returned by DynamicComponentFetch::fetch_ref.

type Mut<'w> = HashMap<ComponentId, MutUntyped<'w>>

The mutable reference type returned by DynamicComponentFetch::fetch_mut.

unsafe fn fetch_ref( self, cell: UnsafeEntityCell<'_>, ) -> Result<<&HashSet<ComponentId> as DynamicComponentFetch>::Ref<'_>, EntityComponentError>

Returns untyped read-only reference(s) to the component(s) with the given ComponentIds, as determined by self.

unsafe fn fetch_mut( self, cell: UnsafeEntityCell<'_>, ) -> Result<<&HashSet<ComponentId> as DynamicComponentFetch>::Mut<'_>, EntityComponentError>

Returns untyped mutable reference(s) to the component(s) with the given ComponentIds, as determined by self.

unsafe fn fetch_mut_assume_mutable( self, cell: UnsafeEntityCell<'_>, ) -> Result<<&HashSet<ComponentId> as DynamicComponentFetch>::Mut<'_>, EntityComponentError>

Returns untyped mutable reference(s) to the component(s) with the given ComponentIds, as determined by self. Assumes all ComponentIds refer to mutable components.

impl<T, S, X> Extend<X> for HashSet<T, S>

where HashSet<T, S>: Extend<X>,

fn extend<U>(&mut self, iter: U)

where U: IntoIterator<Item = X>,

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

🔬This is a nightly-only experimental API. (extend_one)

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

🔬This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements.

impl<T, const N: usize> From<[T; N]> for HashSet<T>

where T: Eq + Hash,

fn from(value: [T; N]) -> HashSet<T>

Converts to this type from the input type.

impl<T, S> From<HashMap<T, (), S>> for HashSet<T, S>

fn from(value: HashMap<T, (), S>) -> HashSet<T, S>

Converts to this type from the input type.

impl<T, S> From<HashSet<T, S>> for HashSet<T, S>

fn from(value: HashSet<T, S>) -> HashSet<T, S>

Converts to this type from the input type.

impl<T, S> From<HashSet<T, S>> for HashSet<T, S>

fn from(value: HashSet<T, S>) -> HashSet<T, S>

Converts to this type from the input type.

impl<T, S> FromEntitySetIterator<T> for HashSet<T, S>

where T: EntityEquivalent + Hash, S: BuildHasher + Default,

fn from_entity_set_iter<I>(set_iter: I) -> HashSet<T, S>

where I: EntitySet<Item = T>,

Creates a value from an EntitySetIterator.

impl<T, S, X> FromIterator<X> for HashSet<T, S>

where HashSet<T, S>: FromIterator<X>,

fn from_iter<U>(iter: U) -> HashSet<T, S>

where U: IntoIterator<Item = X>,

Creates a value from an iterator.

impl<V, S> FromReflect for HashSet<V, S>

where V: FromReflect + TypePath + GetTypeRegistration + Eq + Hash, S: TypePath + BuildHasher + Default + Send + Sync,

fn from_reflect( reflect: &(dyn PartialReflect + 'static), ) -> Option<HashSet<V, S>>

Constructs a concrete instance of Self from a reflected value.

fn take_from_reflect( reflect: Box<dyn PartialReflect>, ) -> Result<Self, Box<dyn PartialReflect>>

Attempts to downcast the given value to Self using, constructing the value using from_reflect if that fails.

impl<V, S> GetTypeRegistration for HashSet<V, S>

where V: FromReflect + TypePath + GetTypeRegistration + Eq + Hash, S: TypePath + BuildHasher + Default + Send + Sync,

fn get_type_registration() -> TypeRegistration

Returns the default TypeRegistration for this type.

fn register_type_dependencies(registry: &mut TypeRegistry)

Registers other types needed by this type.

impl<'a, T, S> IntoIterator for &'a HashSet<T, S>

where &'a HashSet<T, S>: IntoIterator,

type Item = <&'a HashSet<T, S> as IntoIterator>::Item

The type of the elements being iterated over.

type IntoIter = <&'a HashSet<T, S> as IntoIterator>::IntoIter

Which kind of iterator are we turning this into?

fn into_iter(self) -> <&'a HashSet<T, S> as IntoIterator>::IntoIter

Creates an iterator from a value.

impl<'a, T, S> IntoIterator for &'a mut HashSet<T, S>

where &'a mut HashSet<T, S>: IntoIterator,

type Item = <&'a mut HashSet<T, S> as IntoIterator>::Item

The type of the elements being iterated over.

type IntoIter = <&'a mut HashSet<T, S> as IntoIterator>::IntoIter

Which kind of iterator are we turning this into?

fn into_iter(self) -> <&'a mut HashSet<T, S> as IntoIterator>::IntoIter

Creates an iterator from a value.

impl<T, S> IntoIterator for HashSet<T, S>

where HashSet<T, S>: IntoIterator,

type Item = <HashSet<T, S> as IntoIterator>::Item

The type of the elements being iterated over.

type IntoIter = <HashSet<T, S> as IntoIterator>::IntoIter

Which kind of iterator are we turning this into?

fn into_iter(self) -> <HashSet<T, S> as IntoIterator>::IntoIter

Creates an iterator from a value.

impl<S> MapEntities for HashSet<Entity, S>

where S: BuildHasher + Default,

fn map_entities<E>(&mut self, entity_mapper: &mut E)

where E: EntityMapper,

Updates all Entity references stored inside using entity_mapper.

impl<T, S> PartialEq for HashSet<T, S>

where HashSet<T, S>: PartialEq,

fn eq(&self, other: &HashSet<T, S>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<V, S> PartialReflect for HashSet<V, S>

where V: FromReflect + TypePath + GetTypeRegistration + Eq + Hash, S: TypePath + BuildHasher + Default + Send + Sync,

fn get_represented_type_info(&self) -> Option<&'static TypeInfo>

Returns the TypeInfo of the type represented by this value.

fn into_partial_reflect(self: Box<HashSet<V, S>>) -> Box<dyn PartialReflect>

Casts this type to a boxed, reflected value.

fn as_partial_reflect(&self) -> &(dyn PartialReflect + 'static)

Casts this type to a reflected value.

fn as_partial_reflect_mut(&mut self) -> &mut (dyn PartialReflect + 'static)

Casts this type to a mutable, reflected value.

fn try_into_reflect( self: Box<HashSet<V, S>>, ) -> Result<Box<dyn Reflect>, Box<dyn PartialReflect>>

Attempts to cast this type to a boxed, fully-reflected value.

fn try_as_reflect(&self) -> Option<&(dyn Reflect + 'static)>

Attempts to cast this type to a fully-reflected value.

fn try_as_reflect_mut(&mut self) -> Option<&mut (dyn Reflect + 'static)>

Attempts to cast this type to a mutable, fully-reflected value.

fn apply(&mut self, value: &(dyn PartialReflect + 'static))

Applies a reflected value to this value.

fn try_apply( &mut self, value: &(dyn PartialReflect + 'static), ) -> Result<(), ApplyError>

Tries to apply a reflected value to this value.

fn reflect_kind(&self) -> ReflectKind

Returns a zero-sized enumeration of “kinds” of type.

fn reflect_ref(&self) -> ReflectRef<'_>

Returns an immutable enumeration of “kinds” of type.

fn reflect_mut(&mut self) -> ReflectMut<'_>

Returns a mutable enumeration of “kinds” of type.

fn reflect_owned(self: Box<HashSet<V, S>>) -> ReflectOwned

Returns an owned enumeration of “kinds” of type.

fn reflect_clone(&self) -> Result<Box<dyn Reflect>, ReflectCloneError>

Attempts to clone Self using reflection.

fn reflect_partial_eq( &self, value: &(dyn PartialReflect + 'static), ) -> Option<bool>

Returns a “partial equality” comparison result.

fn clone_value(&self) -> Box<dyn PartialReflect>

👎Deprecated since 0.16.0: to clone reflected values, prefer using reflect_clone. To convert reflected values to dynamic ones, use to_dynamic.

Clones Self into its dynamic representation.

fn to_dynamic(&self) -> Box<dyn PartialReflect>

Converts this reflected value into its dynamic representation based on its kind.

fn reflect_hash(&self) -> Option<u64>

Returns a hash of the value (which includes the type).

fn debug(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Debug formatter for the value.

fn is_dynamic(&self) -> bool

Indicates whether or not this type is a dynamic type.

impl<V, S> Reflect for HashSet<V, S>

where V: FromReflect + TypePath + GetTypeRegistration + Eq + Hash, S: TypePath + BuildHasher + Default + Send + Sync,

fn into_any(self: Box<HashSet<V, S>>) -> Box<dyn Any>

Returns the value as a Box<dyn Any>.

fn as_any(&self) -> &(dyn Any + 'static)

Returns the value as a &dyn Any.

fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)

Returns the value as a &mut dyn Any.

fn into_reflect(self: Box<HashSet<V, S>>) -> Box<dyn Reflect>

Casts this type to a boxed, fully-reflected value.

fn as_reflect(&self) -> &(dyn Reflect + 'static)

Casts this type to a fully-reflected value.

fn as_reflect_mut(&mut self) -> &mut (dyn Reflect + 'static)

Casts this type to a mutable, fully-reflected value.

fn set(&mut self, value: Box<dyn Reflect>) -> Result<(), Box<dyn Reflect>>

Performs a type-checked assignment of a reflected value to this value.

impl<T, S> Serialize for HashSet<T, S>

where HashSet<T, S>: Serialize,

fn serialize<U>( &self, serializer: U, ) -> Result<<U as Serializer>::Ok, <U as Serializer>::Error>

where U: Serializer,

Serialize this value into the given Serde serializer.

impl<V, S> Set for HashSet<V, S>

where V: FromReflect + TypePath + GetTypeRegistration + Eq + Hash, S: TypePath + BuildHasher + Default + Send + Sync,

fn get( &self, value: &(dyn PartialReflect + 'static), ) -> Option<&(dyn PartialReflect + 'static)>

Returns a reference to the value.

fn len(&self) -> usize

Returns the number of elements in the set.

fn iter(&self) -> Box<dyn Iterator<Item = &(dyn PartialReflect + 'static)> + '_>

Returns an iterator over the values of the set.

fn drain(&mut self) -> Vec<Box<dyn PartialReflect>>

Drain the values of this set to get a vector of owned values.

fn insert_boxed(&mut self, value: Box<dyn PartialReflect>) -> bool

Inserts a value into the set.

fn remove(&mut self, value: &(dyn PartialReflect + 'static)) -> bool

Removes a value from the set.

fn contains(&self, value: &(dyn PartialReflect + 'static)) -> bool

Checks if the given value is contained in the set

fn is_empty(&self) -> bool

Returns true if the list contains no elements.

fn clone_dynamic(&self) -> DynamicSet

👎Deprecated since 0.16.0: use to_dynamic_set instead

Clones the set, producing a DynamicSet.

fn to_dynamic_set(&self) -> DynamicSet

Creates a new DynamicSet from this set.

impl<T, S> Sub<&HashSet<T, S>> for &HashSet<T, S>

where &'a HashSet<T, S>: for<'a> Sub<Output = 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>.

type Output = HashSet<T, S>

The resulting type after applying the - operator.

impl<T, S> SubAssign<&HashSet<T, S>> for HashSet<T, S>

where HashSet<T, S>: for<'a> SubAssign<&'a HashSet<T, S>>,

fn sub_assign(&mut self, rhs: &HashSet<T, S>)

Modifies this set to contain the difference of self and rhs.

impl<V, S> TypePath for HashSet<V, S>

where HashSet<V, S>: Any + Send + Sync, V: TypePath, S: TypePath,

fn type_path() -> &'static str

Returns the fully qualified path of the underlying type.

fn short_type_path() -> &'static str

Returns a short, pretty-print enabled path to the type.

fn type_ident() -> Option<&'static str>

Returns the name of the type, or None if it is anonymous.

fn crate_name() -> Option<&'static str>

Returns the name of the crate the type is in, or None if it is anonymous.

fn module_path() -> Option<&'static str>

Returns the path to the module the type is in, or None if it is anonymous.

impl<V, S> Typed for HashSet<V, S>

where V: FromReflect + TypePath + GetTypeRegistration + Eq + Hash, S: TypePath + BuildHasher + Default + Send + Sync,

fn type_info() -> &'static TypeInfo

Returns the compile-time info for the underlying type.

impl<T, S> Eq for HashSet<T, S>

where HashSet<T, S>: Eq,