Struct HashSet

pub struct HashSet<T, S = BuildHasherDefault<AHasher>, A = Global>
where
    A: Allocator,
{ /* private fields */ }

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 rune::alloc::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.try_insert("A Dance With Dragons".to_string())?;
books.try_insert("To Kill a Mockingbird".to_string())?;
books.try_insert("The Odyssey".to_string())?;
books.try_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 rune::alloc::HashSet;

#[derive(Hash, Eq, PartialEq, Debug)]
struct Viking {
    name: String,
    power: usize,
}

let mut vikings = HashSet::new();

vikings.try_insert(Viking { name: "Einar".to_string(), power: 9 })?;
vikings.try_insert(Viking { name: "Einar".to_string(), power: 9 })?;
vikings.try_insert(Viking { name: "Olaf".to_string(), power: 4 })?;
vikings.try_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 rune::alloc::HashSet;
use rune::alloc::prelude::*;

let viking_names: HashSet<&'static str> =
    [ "Einar", "Olaf", "Harald" ].iter().copied().try_collect()?;
// use the values stored in the set

Implementations

impl<T> HashSet<T>

pub fn new() -> HashSet<T>

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 ahash::RandomState or std::collections::hash_map::RandomState as the hasher when creating a HashSet, for example with with_hasher method.

Examples

use rune::alloc::HashSet;
let set: HashSet<i32> = HashSet::new();

pub fn try_with_capacity(capacity: usize) -> Result<HashSet<T>, Error>

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 ahash::RandomState or std::collections::hash_map::RandomState as the hasher when creating a HashSet, for example with try_with_capacity_and_hasher method.

Examples

use rune::alloc::HashSet;
let set: HashSet<i32> = HashSet::try_with_capacity(10)?;
assert!(set.capacity() >= 10);

impl<T, A> HashSet<T, BuildHasherDefault<AHasher>, A>

where T: Hash + Eq, A: Allocator,

pub fn new_in(alloc: A) -> HashSet<T, BuildHasherDefault<AHasher>, A>

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 ahash::RandomState or std::collections::hash_map::RandomState as the hasher when creating a HashSet, for example with with_hasher_in method.

Examples

use rune::alloc::HashSet;
use rune::alloc::alloc::Global;

let set: HashSet<i32> = HashSet::new_in(Global);

pub fn try_with_capacity_in( capacity: usize, alloc: A, ) -> Result<HashSet<T, BuildHasherDefault<AHasher>, A>, Error>

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 ahash::RandomState or std::collections::hash_map::RandomState as the hasher when creating a HashSet, for example with try_with_capacity_and_hasher_in method.

Examples

use rune::alloc::HashSet;
let set: HashSet<i32> = HashSet::try_with_capacity(10)?;
assert!(set.capacity() >= 10);

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

where A: Allocator,

pub fn capacity(&self) -> usize

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

Examples

use rune::alloc::HashSet;

let set: HashSet<i32> = HashSet::try_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 rune::alloc::HashSet;

let mut set = HashSet::new();
set.try_insert("a")?;
set.try_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 rune::alloc::HashSet;

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

pub fn is_empty(&self) -> bool

Returns true if the set contains no elements.

Examples

use rune::alloc::HashSet;

let mut v = HashSet::new();
assert!(v.is_empty());
v.try_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 rune::alloc::HashSet;

let mut set: HashSet<_> = HashSet::try_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());

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 rune::alloc::HashSet;

let mut set: HashSet<i32> = HashSet::try_from([1, 2, 3, 4, 5, 6])?;
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 rune::alloc::{try_vec, HashSet, Vec};
use rune::alloc::prelude::*;

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

let mut evens = drained.into_iter().try_collect::<Vec<_>>()?;
let mut odds = set.into_iter().try_collect::<Vec<_>>()?;
evens.sort();
odds.sort();

assert_eq!(evens, try_vec![0, 2, 4, 6]);
assert_eq!(odds, try_vec![1, 3, 5, 7]);

pub fn clear(&mut self)

Clears the set, removing all values.

Examples

use rune::alloc::HashSet;

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

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

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.

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 ahash::RandomState or 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 rune::alloc::HashSet;
use rune::alloc::hash_map::DefaultHashBuilder;

let s = DefaultHashBuilder::default();
let mut set = HashSet::with_hasher(s);
set.try_insert(2)?;

pub fn try_with_capacity_and_hasher( capacity: usize, hasher: S, ) -> Result<HashSet<T, S>, Error>

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 ahash::RandomState or 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 rune::alloc::HashSet;
use rune::alloc::hash_map::DefaultHashBuilder;

let s = DefaultHashBuilder::default();
let mut set = HashSet::try_with_capacity_and_hasher(10, s)?;
set.try_insert(1)?;

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

where A: Allocator,

pub fn allocator(&self) -> &A

Returns a reference to the underlying allocator.

pub const 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.

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 ahash::RandomState or 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 rune::alloc::HashSet;
use rune::alloc::hash_map::DefaultHashBuilder;

let s = DefaultHashBuilder::default();
let mut set = HashSet::with_hasher(s);
set.try_insert(2)?;

pub fn try_with_capacity_and_hasher_in( capacity: usize, hasher: S, alloc: A, ) -> Result<HashSet<T, S, A>, Error>

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 ahash::RandomState or 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 rune::alloc::HashSet;
use rune::alloc::alloc::Global;
use rune::alloc::hash_map::DefaultHashBuilder;

let s = DefaultHashBuilder::default();
let mut set = HashSet::try_with_capacity_and_hasher_in(10, s, Global)?;
set.try_insert(1)?;

pub fn hasher(&self) -> &S

Returns a reference to the set’s BuildHasher.

Examples

use rune::alloc::HashSet;
use rune::alloc::hash_map::DefaultHashBuilder;

let hasher = DefaultHashBuilder::default();
let set: HashSet<i32> = HashSet::with_hasher(hasher);
let hasher: &DefaultHashBuilder = set.hasher();

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

where T: Eq + Hash, S: BuildHasher, A: Allocator,

pub fn try_reserve(&mut self, additional: usize) -> Result<(), Error>

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 rune::alloc::HashSet;
let mut set: HashSet<i32> = HashSet::new();
set.try_reserve(10).expect("why is the test harness OOMing on 10 bytes?");

pub fn try_shrink_to_fit(&mut self) -> Result<(), Error>

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 rune::alloc::HashSet;

let mut set = HashSet::try_with_capacity(100)?;
set.try_insert(1)?;
set.try_insert(2)?;
assert!(set.capacity() >= 100);
set.try_shrink_to_fit()?;
assert!(set.capacity() >= 2);

pub fn try_shrink_to(&mut self, min_capacity: usize) -> Result<(), Error>

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 rune::alloc::HashSet;

let mut set = HashSet::try_with_capacity(100)?;
set.try_insert(1)?;
set.try_insert(2)?;
assert!(set.capacity() >= 100);
set.try_shrink_to(10)?;
assert!(set.capacity() >= 10);
set.try_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 rune::alloc::HashSet;
use rune::alloc::prelude::*;

let a: HashSet<_> = HashSet::try_from([1, 2, 3])?;
let b: HashSet<_> = HashSet::try_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).copied().try_collect()?;
assert_eq!(diff, HashSet::try_from([1])?);

// Note that difference is not symmetric,
// and `b - a` means something else:
let diff: HashSet<_> = b.difference(&a).copied().try_collect()?;
assert_eq!(diff, HashSet::try_from([4])?);

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 rune::alloc::HashSet;
use rune::alloc::prelude::*;

let a: HashSet<_> = HashSet::try_from([1, 2, 3])?;
let b: HashSet<_> = HashSet::try_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).copied().try_collect()?;
let diff2: HashSet<_> = b.symmetric_difference(&a).copied().try_collect()?;

assert_eq!(diff1, diff2);
assert_eq!(diff1, HashSet::try_from([1, 4])?);

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 rune::alloc::HashSet;
use rune::alloc::prelude::*;

let a: HashSet<_> = HashSet::try_from([1, 2, 3])?;
let b: HashSet<_> = HashSet::try_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).copied().try_collect()?;
assert_eq!(intersection, HashSet::try_from([2, 3])?);

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 rune::alloc::HashSet;
use rune::alloc::prelude::*;

let a: HashSet<_> = HashSet::try_from([1, 2, 3])?;
let b: HashSet<_> = HashSet::try_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).copied().try_collect()?;
assert_eq!(union, HashSet::try_from([1, 2, 3, 4])?);

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 rune::alloc::HashSet;

let set: HashSet<_> = HashSet::try_from([1, 2, 3])?;
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 rune::alloc::HashSet;

let set: HashSet<_> = HashSet::try_from([1, 2, 3])?;
assert_eq!(set.get(&2), Some(&2));
assert_eq!(set.get(&4), None);

pub fn get_or_try_insert(&mut self, value: T) -> Result<&T, Error>

Inserts the given value into the set if it is not present, then returns a reference to the value in the set.

Examples

use rune::alloc::HashSet;

let mut set: HashSet<_> = HashSet::try_from([1, 2, 3])?;
assert_eq!(set.len(), 3);
assert_eq!(set.get_or_try_insert(2)?, &2);
assert_eq!(set.get_or_try_insert(100)?, &100);
assert_eq!(set.len(), 4); // 100 was inserted

pub fn get_or_try_insert_owned<Q>(&mut self, value: &Q) -> Result<&T, Error>

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

Inserts an owned copy of the given value into the set if it is not present, then returns a reference to the value in the set.

Examples

use rune::alloc::{HashSet, String, Error};
use rune::alloc::prelude::*;

let mut set: HashSet<String> = ["cat", "dog", "horse"]
    .iter().map(|&pet| pet.try_to_owned()).try_collect::<Result<_, _>>()??;

assert_eq!(set.len(), 3);
for &pet in &["cat", "dog", "fish"] {
    let value = set.get_or_try_insert_owned(pet)?;
    assert_eq!(value, pet);
}
assert_eq!(set.len(), 4); // a new "fish" was inserted

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

where Q: Hash + Equivalent<T> + ?Sized, F: FnOnce(&Q) -> Result<T, Error>,

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 rune::alloc::{HashSet, String, Error};
use rune::alloc::prelude::*;

let mut set: HashSet<String> = ["cat", "dog", "horse"]
    .iter().map(|&pet| pet.try_to_owned()).try_collect::<Result<_, _>>()??;

assert_eq!(set.len(), 3);
for &pet in &["cat", "dog", "fish"] {
    let value = set.get_or_try_insert_with(pet, str::try_to_owned)?;
    assert_eq!(value, pet);
}
assert_eq!(set.len(), 4); // a new "fish" was inserted

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 rune::alloc::HashSet;
use rune::alloc::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.try_insert()?;
            }
            Occupied(single_entry) => {
                // We've already seen this once, "move" it to dupes.
                single_entry.remove();
                dupe_entry.try_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 rune::alloc::HashSet;

let a = HashSet::try_from([1, 2, 3])?;
let mut b = HashSet::new();

assert_eq!(a.is_disjoint(&b), true);
b.try_insert(4)?;
assert_eq!(a.is_disjoint(&b), true);
b.try_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 rune::alloc::HashSet;

let sup = HashSet::try_from([1, 2, 3])?;
let mut set = HashSet::new();

assert_eq!(set.is_subset(&sup), true);
set.try_insert(2)?;
assert_eq!(set.is_subset(&sup), true);
set.try_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 rune::alloc::HashSet;

let sub = HashSet::try_from([1, 2])?;
let mut set = HashSet::new();

assert_eq!(set.is_superset(&sub), false);

set.try_insert(0)?;
set.try_insert(1)?;
assert_eq!(set.is_superset(&sub), false);

set.try_insert(2)?;
assert_eq!(set.is_superset(&sub), true);

pub fn try_insert(&mut self, value: T) -> Result<bool, Error>

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 rune::alloc::HashSet;

let mut set = HashSet::new();

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

pub fn try_insert_unique_unchecked(&mut self, value: T) -> Result<&T, Error>

Insert a value the set without checking if the value already exists in the set.

Returns a reference to the value just inserted.

This operation is safe if a value does not exist in the set.

However, if a value exists in the set already, the behavior is unspecified: this operation may panic, loop forever, or any following operation with the set may panic, loop forever or return arbitrary result.

That said, this operation (and following operations) are guaranteed to not violate memory safety.

This operation is faster than regular insert, because it does not perform lookup before insertion.

This operation is useful during initial population of the set. For example, when constructing a set from another set, we know that values are unique.

pub fn try_replace(&mut self, value: T) -> Result<Option<T>, Error>

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 rune::alloc::HashSet;

let mut set = HashSet::new();
set.try_insert(Vec::<i32>::new())?;

assert_eq!(set.get(&[][..]).unwrap().capacity(), 0);
set.try_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 rune::alloc::HashSet;

let mut set = HashSet::new();

set.try_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 rune::alloc::HashSet;

let mut set: HashSet<_> = HashSet::try_from([1, 2, 3])?;
assert_eq!(set.take(&2), Some(2));
assert_eq!(set.take(&2), None);

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

where A: Allocator,

pub fn raw_table(&self) -> &RawTable<(T, ()), A>

Returns a reference to the RawTable used underneath HashSet. This function is only available if the raw feature of the crate is enabled.

Note

Calling this function is safe, but using the raw hash table API may require unsafe functions or blocks.

RawTable API gives the lowest level of control under the set that can be useful for extending the HashSet’s API, but may lead to undefined behavior.

pub fn raw_table_mut(&mut self) -> &mut RawTable<(T, ()), A>

Returns a mutable reference to the RawTable used underneath HashSet. This function is only available if the raw feature of the crate is enabled.

Note

Calling this function is safe, but using the raw hash table API may require unsafe functions or blocks.

RawTable API gives the lowest level of control under the set that can be useful for extending the HashSet’s API, but may lead to undefined behavior.

Trait Implementations

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

where T: Debug, A: Allocator,

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

Formats the value using the given formatter.

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

where S: Default, A: Default + Allocator,

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

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

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

where T: Deserialize<'de> + Eq + Hash, S: BuildHasher + Default, A: Allocator + Default,

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

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

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

where A: Allocator,

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

Converts to this type from the input type.

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

where A: Allocator,

type Item = &'a T

The type of the elements being iterated over.

type IntoIter = Iter<'a, T>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Iter<'a, T>

Creates an iterator from a value.

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

where A: Allocator,

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 rune::alloc::prelude::*;
use rune::alloc::HashSet;

let mut set = HashSet::new();
set.try_insert("a".try_to_string()?)?;
set.try_insert("b".try_to_string()?)?;

// Not possible to collect to a Vec<String> with a regular `.iter()`.
let v: Vec<String> = set.into_iter().try_collect()?;

// Will print in an arbitrary order.
for x in &v {
    println!("{}", x);
}

type Item = T

The type of the elements being iterated over.

type IntoIter = IntoIter<T, A>

Which kind of iterator are we turning this into?

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

where T: Eq + Hash, S: BuildHasher, A: Allocator,

fn eq(&self, other: &HashSet<T, S, A>) -> 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<T, H, A> Serialize for HashSet<T, H, A>

where T: Serialize + Eq + Hash, H: BuildHasher, A: Allocator,

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

where S: Serializer,

Serialize this value into the given Serde serializer.

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

where A: Allocator + Clone, T: TryClone, S: Clone,

fn try_clone(&self) -> Result<HashSet<T, S, A>, Error>

Try to clone the current value, raising an allocation error if it’s unsuccessful.

fn try_clone_from(&mut self, source: &HashSet<T, S, A>) -> Result<(), Error>

Performs copy-assignment from source.

impl<'a, T, S, A> TryExtend<&'a T> for HashSet<T, S, A>

where T: 'a + Eq + Hash + Copy, S: BuildHasher, A: Allocator,

fn try_extend<I>(&mut self, iter: I) -> Result<(), Error>

where I: IntoIterator<Item = &'a T>,

Extends a collection with the contents of an iterator.

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

where T: Eq + Hash, S: BuildHasher, A: Allocator,

fn try_extend<I>(&mut self, iter: I) -> Result<(), Error>

where I: IntoIterator<Item = T>,

Extends a collection with the contents of an iterator.

impl<T, A, const N: usize> TryFrom<[T; N]> for HashSet<T, BuildHasherDefault<AHasher>, A>

where A: Allocator + Default, T: Eq + Hash,

fn try_from( arr: [T; N], ) -> Result<HashSet<T, BuildHasherDefault<AHasher>, A>, <HashSet<T, BuildHasherDefault<AHasher>, A> as TryFrom<[T; N]>>::Error>

Examples

use rune::alloc::HashSet;

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

type Error = Error

The type returned in the event of a conversion error.

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

where A: Allocator, T: Eq + Hash, S: BuildHasher + Default,

fn try_from_iter_in<I>(iter: I, alloc: A) -> Result<HashSet<T, S, A>, Error>

where I: IntoIterator<Item = T>,

Creates a value from an iterator within an allocator.

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

where T: Eq + Hash, S: BuildHasher, A: Allocator,