Struct im::HashSet

pub struct HashSet<A, S = RandomState> { /* fields omitted */ }

[−] Expand description

An unordered set.

An immutable hash set using [hash array mapped tries] 1.

Most operations on this set are O(log_x n) for a suitably high x that it should be nearly O(1) for most sets. Because of this, it’s a great choice for a generic set as long as you don’t mind that values will need to implement Hash and Eq.

Values will have a predictable order based on the hasher being used. Unless otherwise specified, this will be the standard RandomState hasher.

Implementations

impl<A> HashSet<A, RandomState>[−]

#[must_use]

pub fn new() -> Self[−]

Construct an empty set.

impl<A> HashSet<A, RandomState> where
    A: Hash + Eq + Clone, [−]

#[must_use]

pub fn unit(a: A) -> Self[−]

Construct a set with a single value.

Examples

let set = HashSet::unit(123);
assert!(set.contains(&123));

impl<A, S> HashSet<A, S>[−]

#[must_use]

pub fn is_empty(&self) -> bool[−]

Test whether a set is empty.

Time: O(1)

Examples

assert!(
  !hashset![1, 2, 3].is_empty()
);
assert!(
  HashSet::<i32>::new().is_empty()
);

#[must_use]

pub fn len(&self) -> usize[−]

Get the size of a set.

Time: O(1)

Examples

assert_eq!(3, hashset![1, 2, 3].len());

pub fn ptr_eq(&self, other: &Self) -> bool[−]

Test whether two sets refer to the same content in memory.

This is true if the two sides are references to the same set, or if the two sets refer to the same root node.

This would return true if you’re comparing a set to itself, or if you’re comparing a set to a fresh clone of itself.

Time: O(1)

#[must_use]

pub fn with_hasher<RS>(hasher: RS) -> Self where
    Arc<S>: From<RS>, [−]

Construct an empty hash set using the provided hasher.

#[must_use]

pub fn hasher(&self) -> &Arc<S>[−]

Get a reference to the set’s BuildHasher.

#[must_use]

pub fn new_from<A1>(&self) -> HashSet<A1, S> where
    A1: Hash + Eq + Clone, [−]

Construct an empty hash set using the same hasher as the current hash set.

pub fn clear(&mut self)[−]

Discard all elements from the set.

This leaves you with an empty set, and all elements that were previously inside it are dropped.

Time: O(n)

Examples

let mut set = hashset![1, 2, 3];
set.clear();
assert!(set.is_empty());

#[must_use]

pub fn iter(&self) -> Iter<'_, A>[−]

Get an iterator over the values in a hash set.

Please note that the order is consistent between sets using the same hasher, but no other ordering guarantee is offered. Items will not come out in insertion order or sort order. They will, however, come out in the same order every time for the same set.

impl<A, S> HashSet<A, S> where
    A: Hash + Eq,
    S: BuildHasher, [−]

#[must_use]

pub fn contains<BA: ?Sized>(&self, a: &BA) -> bool where
    BA: Hash + Eq,
    A: Borrow<BA>, [−]

Test if a value is part of a set.

Time: O(log n)

#[must_use]

pub fn is_subset<RS>(&self, other: RS) -> bool where
    RS: Borrow<Self>, [−]

Test whether a set is a subset of another set, meaning that all values in our set must also be in the other set.

Time: O(n log n)

#[must_use]

pub fn is_proper_subset<RS>(&self, other: RS) -> bool where
    RS: Borrow<Self>, [−]

Test whether a set is a proper subset of another set, meaning that all values in our set must also be in the other set. A proper subset must also be smaller than the other set.

Time: O(n log n)

impl<A, S> HashSet<A, S> where
    A: Hash + Eq + Clone,
    S: BuildHasher, [−]

pub fn insert(&mut self, a: A) -> Option<A>[−]

Insert a value into a set.

Time: O(log n)

pub fn remove<BA: ?Sized>(&mut self, a: &BA) -> Option<A> where
    BA: Hash + Eq,
    A: Borrow<BA>, [−]

Remove a value from a set if it exists.

Time: O(log n)

#[must_use]

pub fn update(&self, a: A) -> Self[−]

Construct a new set from the current set with the given value added.

Time: O(log n)

Examples

let set = hashset![123];
assert_eq!(
  set.update(456),
  hashset![123, 456]
);

#[must_use]

pub fn without<BA: ?Sized>(&self, a: &BA) -> Self where
    BA: Hash + Eq,
    A: Borrow<BA>, [−]

Construct a new set with the given value removed if it’s in the set.

Time: O(log n)

pub fn retain<F>(&mut self, f: F) where
    F: FnMut(&A) -> bool, [−]

Filter out values from a set which don’t satisfy a predicate.

This is slightly more efficient than filtering using an iterator, in that it doesn’t need to rehash the retained values, but it still needs to reconstruct the entire tree structure of the set.

Time: O(n log n)

Examples

let mut set = hashset![1, 2, 3];
set.retain(|v| *v > 1);
let expected = hashset![2, 3];
assert_eq!(expected, set);

#[must_use]

pub fn union(self, other: Self) -> Self[−]

Construct the union of two sets.

Time: O(n log n)

Examples

let set1 = hashset!{1, 2};
let set2 = hashset!{2, 3};
let expected = hashset!{1, 2, 3};
assert_eq!(expected, set1.union(set2));

#[must_use]

pub fn unions<I>(i: I) -> Self where
    I: IntoIterator<Item = Self>,
    S: Default, [−]

Construct the union of multiple sets.

Time: O(n log n)

#[must_use]

pub fn difference(self, other: Self) -> Self[−]

Construct the symmetric difference between two sets.

This is an alias for the symmetric_difference method.

Time: O(n log n)

Examples

let set1 = hashset!{1, 2};
let set2 = hashset!{2, 3};
let expected = hashset!{1, 3};
assert_eq!(expected, set1.difference(set2));

#[must_use]

pub fn symmetric_difference(self, other: Self) -> Self[−]

Construct the symmetric difference between two sets.

Time: O(n log n)

Examples

let set1 = hashset!{1, 2};
let set2 = hashset!{2, 3};
let expected = hashset!{1, 3};
assert_eq!(expected, set1.symmetric_difference(set2));

#[must_use]

pub fn relative_complement(self, other: Self) -> Self[−]

Construct the relative complement between two sets, that is the set of values in self that do not occur in other.

Time: O(m log n) where m is the size of the other set

Examples

let set1 = ordset!{1, 2};
let set2 = ordset!{2, 3};
let expected = ordset!{1};
assert_eq!(expected, set1.relative_complement(set2));

#[must_use]

pub fn intersection(self, other: Self) -> Self[−]

Construct the intersection of two sets.

Time: O(n log n)

Examples

let set1 = hashset!{1, 2};
let set2 = hashset!{2, 3};
let expected = hashset!{2};
assert_eq!(expected, set1.intersection(set2));

Trait Implementations

impl<'a, A, S> Add<&'a HashSet<A, S>> for &'a HashSet<A, S> where
    A: Hash + Eq + Clone,
    S: BuildHasher, [+]

[+] Show hidden undocumented items

type Output = HashSet<A, S>

The resulting type after applying the + operator.

fn add(self, other: Self) -> Self::Output[−]

Performs the + operation.

impl<A, S> Add<HashSet<A, S>> for HashSet<A, S> where
    A: Hash + Eq + Clone,
    S: BuildHasher, [+]

[+] Show hidden undocumented items

type Output = HashSet<A, S>

The resulting type after applying the + operator.

fn add(self, other: Self) -> Self::Output[−]

Performs the + operation.

impl<A, S> Clone for HashSet<A, S> where
    A: Clone, [+]

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fn clone(&self) -> Self[−]

Clone a set.

Time: O(1)

pub fn clone_from(&mut self, source: &Self)[−]

Performs copy-assignment from source.

impl<A, S> Debug for HashSet<A, S> where
    A: Hash + Eq + Debug,
    S: BuildHasher, [+]

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

Formats the value using the given formatter.

impl<A, S> Debug for HashSet<A, S> where
    A: Hash + Eq + Debug + Ord,
    S: BuildHasher, [+]

[+] Show hidden undocumented items

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

Formats the value using the given formatter.

impl<A, S> Default for HashSet<A, S> where
    S: BuildHasher + Default, [+]

[+] Show hidden undocumented items

fn default() -> Self[−]

Returns the “default value” for a type.

impl<A, S> Eq for HashSet<A, S> where
    A: Hash + Eq,
    S: BuildHasher + Default, 

impl<A, S, R> Extend<R> for HashSet<A, S> where
    A: Hash + Eq + Clone + From<R>,
    S: BuildHasher, [+]

[+] Show hidden undocumented items

fn extend<I>(&mut self, iter: I) where
    I: IntoIterator<Item = R>, [−]

Extends a collection with the contents of an iterator.

pub fn extend_one(&mut self, item: A)[−]

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

Extends a collection with exactly one element.

pub 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<'a, A, S> From<&'a [A]> for HashSet<A, S> where
    A: Hash + Eq + Clone,
    S: BuildHasher + Default, [+]

[+] Show hidden undocumented items

fn from(slice: &'a [A]) -> Self[−]

Performs the conversion.

impl<'a, A, S> From<&'a BTreeSet<A>> for HashSet<A, S> where
    A: Hash + Eq + Clone,
    S: BuildHasher + Default, [+]

[+] Show hidden undocumented items

fn from(btree_set: &BTreeSet<A>) -> Self[−]

Performs the conversion.

impl<'a, A, S> From<&'a HashSet<A, RandomState>> for HashSet<A, S> where
    A: Eq + Hash + Clone,
    S: BuildHasher + Default, [+]

[+] Show hidden undocumented items

fn from(hash_set: &HashSet<A>) -> Self[−]

Performs the conversion.

impl<'a, A: Hash + Eq + Ord + Clone, S: BuildHasher> From<&'a HashSet<A, S>> for OrdSet<A>[+]

[+] Show hidden undocumented items

fn from(hashset: &HashSet<A, S>) -> Self[−]

Performs the conversion.

impl<'a, A, S> From<&'a OrdSet<A>> for HashSet<A, S> where
    A: Ord + Hash + Eq + Clone,
    S: BuildHasher + Default, [+]

[+] Show hidden undocumented items

fn from(ordset: &OrdSet<A>) -> Self[−]

Performs the conversion.

impl<'a, A, S> From<&'a Vec<A, Global>> for HashSet<A, S> where
    A: Hash + Eq + Clone,
    S: BuildHasher + Default, [+]

[+] Show hidden undocumented items

fn from(vec: &Vec<A>) -> Self[−]

Performs the conversion.

impl<'s, 'a, A: ?Sized, OA, SA, SB> From<&'s HashSet<&'a A, SA>> for HashSet<OA, SB> where
    A: ToOwned<Owned = OA> + Hash + Eq,
    OA: Borrow<A> + Hash + Eq + Clone,
    SA: BuildHasher,
    SB: BuildHasher + Default, [+]

[+] Show hidden undocumented items

fn from(set: &HashSet<&A, SA>) -> Self[−]

Performs the conversion.

impl<A, S> From<HashSet<A, RandomState>> for HashSet<A, S> where
    A: Eq + Hash + Clone,
    S: BuildHasher + Default, [+]

[+] Show hidden undocumented items

fn from(hash_set: HashSet<A>) -> Self[−]

Performs the conversion.

impl<A: Hash + Eq + Ord + Clone, S: BuildHasher> From<HashSet<A, S>> for OrdSet<A>[+]

[+] Show hidden undocumented items

fn from(hashset: HashSet<A, S>) -> Self[−]

Performs the conversion.

impl<A, S> From<OrdSet<A>> for HashSet<A, S> where
    A: Ord + Hash + Eq + Clone,
    S: BuildHasher + Default, [+]

[+] Show hidden undocumented items

fn from(ordset: OrdSet<A>) -> Self[−]

Performs the conversion.

impl<A, S> From<Vec<A, Global>> for HashSet<A, S> where
    A: Hash + Eq + Clone,
    S: BuildHasher + Default, [+]

[+] Show hidden undocumented items

fn from(vec: Vec<A>) -> Self[−]

Performs the conversion.

impl<A, RA, S> FromIterator<RA> for HashSet<A, S> where
    A: Hash + Eq + Clone + From<RA>,
    S: BuildHasher + Default, [+]

[+] Show hidden undocumented items

fn from_iter<T>(i: T) -> Self where
    T: IntoIterator<Item = RA>, [−]

Creates a value from an iterator.

impl<A, S> Hash for HashSet<A, S> where
    A: Hash + Eq,
    S: BuildHasher + Default, [+]

[+] Show hidden undocumented items

fn hash<H>(&self, state: &mut H) where
    H: Hasher, [−]

Feeds this value into the given Hasher.

pub fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, [−]

Feeds a slice of this type into the given Hasher.

impl<'a, A, S> IntoIterator for &'a HashSet<A, S> where
    A: Hash + Eq,
    S: BuildHasher, [+]

[+] Show hidden undocumented items

type Item = &'a A

The type of the elements being iterated over.

type IntoIter = Iter<'a, A>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter[−]

Creates an iterator from a value.

impl<A, S> IntoIterator for HashSet<A, S> where
    A: Hash + Eq + Clone,
    S: BuildHasher, [+]

[+] Show hidden undocumented items

type Item = A

The type of the elements being iterated over.

type IntoIter = ConsumingIter<Self::Item>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter[−]

Creates an iterator from a value.

impl<'a, A, S> Mul<&'a HashSet<A, S>> for &'a HashSet<A, S> where
    A: Hash + Eq + Clone,
    S: BuildHasher, [+]

[+] Show hidden undocumented items

type Output = HashSet<A, S>

The resulting type after applying the * operator.

fn mul(self, other: Self) -> Self::Output[−]

Performs the * operation.

impl<A, S> Mul<HashSet<A, S>> for HashSet<A, S> where
    A: Hash + Eq + Clone,
    S: BuildHasher, [+]

[+] Show hidden undocumented items

type Output = HashSet<A, S>

The resulting type after applying the * operator.

fn mul(self, other: Self) -> Self::Output[−]

Performs the * operation.

impl<A, S> Ord for HashSet<A, S> where
    A: Hash + Eq + Clone + Ord,
    S: BuildHasher + Default, [+]

[+] Show hidden undocumented items

fn cmp(&self, other: &Self) -> Ordering[−]

This method returns an Ordering between self and other.

#[must_use]

pub fn max(self, other: Self) -> Self[−]

Compares and returns the maximum of two values.

#[must_use]

pub fn min(self, other: Self) -> Self[−]

Compares and returns the minimum of two values.

#[must_use]

pub fn clamp(self, min: Self, max: Self) -> Self[−]

Restrict a value to a certain interval.

impl<A, S> PartialEq<HashSet<A, S>> for HashSet<A, S> where
    A: Hash + Eq,
    S: BuildHasher + Default, [+]

[+] Show hidden undocumented items

fn eq(&self, other: &Self) -> bool[−]

This method tests for self and other values to be equal, and is used by ==.

#[must_use]

pub fn ne(&self, other: &Rhs) -> bool[−]

This method tests for !=.

impl<A, S> PartialOrd<HashSet<A, S>> for HashSet<A, S> where
    A: Hash + Eq + Clone + PartialOrd,
    S: BuildHasher + Default, [+]

[+] Show hidden undocumented items

fn partial_cmp(&self, other: &Self) -> Option<Ordering>[−]

This method returns an ordering between self and other values if one exists.

#[must_use]

pub fn lt(&self, other: &Rhs) -> bool[−]

This method tests less than (for self and other) and is used by the < operator.

#[must_use]

pub fn le(&self, other: &Rhs) -> bool[−]

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use]

pub fn gt(&self, other: &Rhs) -> bool[−]

This method tests greater than (for self and other) and is used by the > operator.

#[must_use]

pub fn ge(&self, other: &Rhs) -> bool[−]

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<A, S> Sum<HashSet<A, S>> for HashSet<A, S> where
    A: Hash + Eq + Clone,
    S: BuildHasher + Default, [+]

[+] Show hidden undocumented items

fn sum<I>(it: I) -> Self where
    I: Iterator<Item = Self>, [−]

Method which takes an iterator and generates Self from the elements by “summing up” the items.