Struct HashSet

struct HashSet<T, S = crate::hash::RandomState, A: Allocator = crate::alloc::Global> { ... }

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. Violating this property is a logic error.

It is also a logic error for a key to be modified in such a way that the key's hash, as determined by the Hash trait, or its equality, as determined by the Eq trait, changes while it is in the map. This is normally only possible through Cell, RefCell, global state, I/O, or unsafe code.

The behavior resulting from either logic error is not specified, but will be encapsulated to the HashSet that observed the logic error and not result in undefined behavior. This could include panics, incorrect results, aborts, memory leaks, and non-termination.

Examples

use std::collections::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, which is required if Eq is derived.

use std::collections::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 a known list of items can be initialized from an array:

use std::collections::HashSet;

let viking_names = HashSet::from(["Einar", "Olaf", "Harald"]);

Usage in const and static

Like HashMap, HashSet is randomly seeded: each HashSet instance uses a different seed, which means that HashSet::new cannot be used in const context. To construct a HashSet in the initializer of a const or static item, you will have to use a different hasher that does not involve a random seed, as demonstrated in the following example. A HashSet constructed this way is not resistant against HashDoS!

use std::collections::HashSet;
use std::hash::{BuildHasherDefault, DefaultHasher};
use std::sync::Mutex;

const EMPTY_SET: HashSet<String, BuildHasherDefault<DefaultHasher>> =
    HashSet::with_hasher(BuildHasherDefault::new());
static SET: Mutex<HashSet<String, BuildHasherDefault<DefaultHasher>>> =
    Mutex::new(HashSet::with_hasher(BuildHasherDefault::new()));

Implementations

impl<T> HashSet<T, RandomState>

fn new() -> HashSet<T, RandomState>

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 std::collections::HashSet;
let set: HashSet<i32> = HashSet::new();

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

Creates an empty HashSet with at least the specified capacity.

The hash set will be able to hold at least capacity elements without reallocating. This method is allowed to allocate for more elements than capacity. If capacity is zero, the hash set will not allocate.

Examples

use std::collections::HashSet;
let set: HashSet<i32> = HashSet::with_capacity(10);
assert!(set.capacity() >= 10);

impl<T, A: Allocator> HashSet<T, RandomState, A>

fn new_in(alloc: A) -> HashSet<T, RandomState, A>

Creates an empty HashSet in the provided allocator.

The hash set is initially created with a capacity of 0, so it will not allocate until it is first inserted into.

fn with_capacity_in(capacity: usize, alloc: A) -> HashSet<T, RandomState, A>

Creates an empty HashSet with at least the specified capacity.

The hash set will be able to hold at least capacity elements without reallocating. This method is allowed to allocate for more elements than capacity. If capacity is zero, the hash set will not allocate.

Examples

use std::collections::HashSet;
let set: HashSet<i32> = HashSet::with_capacity(10);
assert!(set.capacity() >= 10);

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

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

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 HashSets 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 HashSet to be useful, see its documentation for details.

Examples

use std::collections::HashSet;
use std::hash::RandomState;

let s = RandomState::new();
let mut set = HashSet::with_hasher(s);
set.insert(2);

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

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

The hash set will be able to hold at least capacity elements without reallocating. This method is allowed to allocate for more elements than capacity. If capacity is zero, the hash set will not allocate.

Warning: hasher is normally randomly generated, and is designed to allow HashSets 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 HashSet to be useful, see its documentation for details.

Examples

use std::collections::HashSet;
use std::hash::RandomState;

let s = RandomState::new();
let mut set = HashSet::with_capacity_and_hasher(10, s);
set.insert(1);

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

fn reserve(self: &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 speculatively avoid frequent reallocations. After calling reserve, capacity will be greater than or equal to self.len() + additional. Does nothing if capacity is already sufficient.

Panics

Panics if the new allocation size overflows usize.

Examples

use std::collections::HashSet;
let mut set: HashSet<i32> = HashSet::new();
set.reserve(10);
assert!(set.capacity() >= 10);

fn try_reserve(self: &mut Self, additional: usize) -> Result<(), TryReserveError>

Tries to reserve capacity for at least additional more elements to be inserted in the HashSet. The collection may reserve more space to speculatively avoid frequent reallocations. After calling try_reserve, capacity will be greater than or equal to self.len() + additional if it returns Ok(()). Does nothing if capacity is already sufficient.

Errors

If the capacity overflows, or the allocator reports a failure, then an error is returned.

Examples

use std::collections::HashSet;
let mut set: HashSet<i32> = HashSet::new();
set.try_reserve(10).expect("why is the test harness OOMing on a handful of bytes?");

fn shrink_to_fit(self: &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 std::collections::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);

fn shrink_to(self: &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.

If the current capacity is less than the lower limit, this is a no-op.

Examples

use std::collections::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);

fn difference<'a>(self: &'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 std::collections::HashSet;
let a = HashSet::from([1, 2, 3]);
let b = HashSet::from([4, 2, 3, 4]);

// 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());

fn symmetric_difference<'a>(self: &'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 std::collections::HashSet;
let a = HashSet::from([1, 2, 3]);
let b = HashSet::from([4, 2, 3, 4]);

// 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());

fn intersection<'a>(self: &'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.

When an equal element is present in self and other then the resulting Intersection may yield references to one or the other. This can be relevant if T contains fields which are not compared by its Eq implementation, and may hold different value between the two equal copies of T in the two sets.

Examples

use std::collections::HashSet;
let a = HashSet::from([1, 2, 3]);
let b = HashSet::from([4, 2, 3, 4]);

// 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());

fn union<'a>(self: &'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 std::collections::HashSet;
let a = HashSet::from([1, 2, 3]);
let b = HashSet::from([4, 2, 3, 4]);

// 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());

fn contains<Q>(self: &Self, value: &Q) -> bool
where
    T: Borrow<Q>,
    Q: Hash + Eq + ?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 std::collections::HashSet;

let set = HashSet::from([1, 2, 3]);
assert_eq!(set.contains(&1), true);
assert_eq!(set.contains(&4), false);

fn get<Q>(self: &Self, value: &Q) -> Option<&T>
where
    T: Borrow<Q>,
    Q: Hash + Eq + ?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 std::collections::HashSet;

let set = HashSet::from([1, 2, 3]);
assert_eq!(set.get(&2), Some(&2));
assert_eq!(set.get(&4), None);

fn get_or_insert(self: &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

#![feature(hash_set_entry)]

use std::collections::HashSet;

let mut set = HashSet::from([1, 2, 3]);
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

fn get_or_insert_with<Q, F>(self: &mut Self, value: &Q, f: F) -> &T
where
    T: Borrow<Q>,
    Q: Hash + Eq + ?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

#![feature(hash_set_entry)]

use std::collections::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

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

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

Examples

#![feature(hash_set_entry)]

use std::collections::HashSet;
use std::collections::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'));

fn is_disjoint(self: &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 std::collections::HashSet;

let a = HashSet::from([1, 2, 3]);
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);

fn is_subset(self: &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 std::collections::HashSet;

let sup = HashSet::from([1, 2, 3]);
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);

fn is_superset(self: &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 std::collections::HashSet;

let sub = HashSet::from([1, 2]);
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);

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

Adds a value to the set.

Returns whether the value was newly inserted. That is:

  • If the set did not previously contain this value, true is returned.
  • If the set already contained this value, false is returned, and the set is not modified: original value is not replaced, and the value passed as argument is dropped.

Examples

use std::collections::HashSet;

let mut set = HashSet::new();

assert_eq!(set.insert(2), true);
assert_eq!(set.insert(2), false);
assert_eq!(set.len(), 1);

fn replace(self: &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 std::collections::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);

fn remove<Q>(self: &mut Self, value: &Q) -> bool
where
    T: Borrow<Q>,
    Q: Hash + Eq + ?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 std::collections::HashSet;

let mut set = HashSet::new();

set.insert(2);
assert_eq!(set.remove(&2), true);
assert_eq!(set.remove(&2), false);

fn take<Q>(self: &mut Self, value: &Q) -> Option<T>
where
    T: Borrow<Q>,
    Q: Hash + Eq + ?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 std::collections::HashSet;

let mut set = HashSet::from([1, 2, 3]);
assert_eq!(set.take(&2), Some(2));
assert_eq!(set.take(&2), None);

impl<T, S, A: Allocator> HashSet<T, S, A>

fn with_hasher_in(hasher: S, alloc: A) -> HashSet<T, S, A>

Creates a new empty hash set which will use the given hasher to hash keys and will allocate memory using the provided allocator.

The hash set is also created with the default initial capacity.

Warning: hasher is normally randomly generated, and is designed to allow HashSets 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 HashSet to be useful, see its documentation for details.

fn with_capacity_and_hasher_in(capacity: usize, hasher: S, alloc: A) -> HashSet<T, S, A>

Creates an empty HashSet with at least the specified capacity, using hasher to hash the keys and alloc to allocate memory.

The hash set will be able to hold at least capacity elements without reallocating. This method is allowed to allocate for more elements than capacity. If capacity is zero, the hash set will not allocate.

Warning: hasher is normally randomly generated, and is designed to allow HashSets 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 HashSet to be useful, see its documentation for details.

fn capacity(self: &Self) -> usize

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

Examples

use std::collections::HashSet;
let set: HashSet<i32> = HashSet::with_capacity(100);
assert!(set.capacity() >= 100);

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

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

Examples

use std::collections::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}");
}

Performance

In the current implementation, iterating over set takes O(capacity) time instead of O(len) because it internally visits empty buckets too.

fn len(self: &Self) -> usize

Returns the number of elements in the set.

Examples

use std::collections::HashSet;

let mut v = HashSet::new();
assert_eq!(v.len(), 0);
v.insert(1);
assert_eq!(v.len(), 1);

fn is_empty(self: &Self) -> bool

Returns true if the set contains no elements.

Examples

use std::collections::HashSet;

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

fn drain(self: &mut Self) -> Drain<'_, T, A>

Clears the set, returning all elements as an iterator. Keeps the allocated memory for reuse.

If the returned iterator is dropped before being fully consumed, it drops the remaining elements. The returned iterator keeps a mutable borrow on the set to optimize its implementation.

Examples

use std::collections::HashSet;

let mut set = HashSet::from([1, 2, 3]);
assert!(!set.is_empty());

// print 1, 2, 3 in an arbitrary order
for i in set.drain() {
    println!("{i}");
}

assert!(set.is_empty());

fn extract_if<F>(self: &mut Self, pred: F) -> ExtractIf<'_, T, F, A>
where
    F: FnMut(&T) -> bool

Creates an iterator which uses a closure to determine if an element should be removed.

If the closure returns true, the element is removed from the set and yielded. If the closure returns false, or panics, the element remains in the set and will not be yielded.

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

Splitting a set into even and odd values, reusing the original set:

use std::collections::HashSet;

let mut set: HashSet<i32> = (0..8).collect();
let extracted: HashSet<i32> = set.extract_if(|v| v % 2 == 0).collect();

let mut evens = extracted.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]);

fn retain<F>(self: &mut Self, f: F)
where
    F: FnMut(&T) -> bool

Retains only the elements specified by the predicate.

In other words, remove all elements e for which f(&e) returns false. The elements are visited in unsorted (and unspecified) order.

Examples

use std::collections::HashSet;

let mut set = HashSet::from([1, 2, 3, 4, 5, 6]);
set.retain(|&k| k % 2 == 0);
assert_eq!(set, HashSet::from([2, 4, 6]));

Performance

In the current implementation, this operation takes O(capacity) time instead of O(len) because it internally visits empty buckets too.

fn clear(self: &mut Self)

Clears the set, removing all values.

Examples

use std::collections::HashSet;

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

fn hasher(self: &Self) -> &S

Returns a reference to the set's BuildHasher.

Examples

use std::collections::HashSet;
use std::hash::RandomState;

let hasher = RandomState::new();
let set: HashSet<i32> = HashSet::with_hasher(hasher);
let hasher: &RandomState = set.hasher();

impl<'a, T, S, A> Extend for HashSet<T, S, A>

fn extend<I: IntoIterator<Item = &'a T>>(self: &mut Self, iter: I)
fn extend_one(self: &mut Self, item: &'a T)
fn extend_reserve(self: &mut Self, additional: usize)

impl<T> Any for HashSet<T, S, A>

fn type_id(self: &Self) -> TypeId

impl<T> Borrow for HashSet<T, S, A>

fn borrow(self: &Self) -> &T

impl<T> BorrowMut for HashSet<T, S, A>

fn borrow_mut(self: &mut Self) -> &mut T

impl<T> CloneToUninit for HashSet<T, S, A>

unsafe fn clone_to_uninit(self: &Self, dest: *mut u8)

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

fn from(t: T) -> T

Returns the argument unchanged.

impl<T> ToOwned for HashSet<T, S, A>

fn to_owned(self: &Self) -> T
fn clone_into(self: &Self, target: &mut T)

impl<T, N: usize> From for HashSet<T, RandomState>

fn from(arr: [T; N]) -> Self

Converts a [T; N] into a HashSet<T>.

If the array contains any equal values, all but one will be dropped.

Examples

use std::collections::HashSet;

let set1 = HashSet::from([1, 2, 3, 4]);
let set2: HashSet<_> = [1, 2, 3, 4].into();
assert_eq!(set1, set2);

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

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

Creates an empty HashSet<T, S> with the Default value for the hasher.

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

fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> HashSet<T, S>

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

fn clone(self: &Self) -> Self
fn clone_from(self: &mut Self, other: &Self)

Overwrites the contents of self with a clone of the contents of source.

This method is preferred over simply assigning source.clone() to self, as it avoids reallocation if possible.

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

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

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

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

fn extend<I: IntoIterator<Item = T>>(self: &mut Self, iter: I)
fn extend_one(self: &mut Self, item: T)
fn extend_reserve(self: &mut Self, additional: usize)

impl<T, S, A> Freeze for HashSet<T, S, A>

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

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

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> UnsafeUnpin for HashSet<T, S, A>

impl<T, S, A> UnwindSafe for HashSet<T, S, A>

impl<T, S, A: Allocator> IntoIterator for HashSet<T, S, A>

fn into_iter(self: 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 std::collections::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}");
}

impl<T, U> Into for HashSet<T, S, A>

fn into(self: Self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of [From]<T> for U chooses to do.

impl<T, U> TryFrom for HashSet<T, S, A>

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

impl<T, U> TryInto for HashSet<T, S, A>

fn try_into(self: Self) -> Result<U, <U as TryFrom<T>>::Error>