Struct WeakHashSet

pub struct WeakHashSet<T, S = RandomState>(/* private fields */);

A hash set with weak elements, hashed on element value.

When a weak pointer expires, its mapping is lazily removed.

Implementations

impl<T: WeakKey> WeakHashSet<T, RandomState>

pub fn new() -> Self

Creates an empty WeakHashSet.

O(1) time

pub fn with_capacity(capacity: usize) -> Self

Creates an empty WeakHashSet with the given capacity.

O(n) time

impl<T: WeakKey, S: BuildHasher> WeakHashSet<T, S>

pub fn with_hasher(hash_builder: S) -> Self

Creates an empty WeakHashSet with the given capacity and hasher.

O(n) time

pub fn with_capacity_and_hasher(capacity: usize, hash_builder: S) -> Self

Creates an empty WeakHashSet with the given capacity and hasher.

O(n) time

pub fn hasher(&self) -> &S

Returns a reference to the map’s BuildHasher.

O(1) time

pub fn capacity(&self) -> usize

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

O(1) time

pub fn remove_expired(&mut self)

Removes all mappings whose keys have expired.

O(n) time

pub fn reserve(&mut self, additional_capacity: usize)

Reserves room for additional elements.

O(n) time

pub fn shrink_to_fit(&mut self)

Shrinks the capacity to the minimum allowed to hold the current number of elements.

O(n) time

pub fn len(&self) -> usize

Returns an over-approximation of the number of elements.

O(1) time

pub fn is_empty(&self) -> bool

Is the set empty?

Note that this may return false even if all keys in the set have expired, if they haven’t been collected yet.

O(1) time

pub fn load_factor(&self) -> f32

The proportion of buckets that are used.

This is an over-approximation because of expired elements.

O(1) time

pub fn clear(&mut self)

Removes all associations from the map.

O(n) time

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

where Q: ?Sized + Eq + Hash, T::Key: Borrow<Q>,

Returns true if the map contains the specified key.

expected O(1) time; worst-case O(p) time

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

where Q: ?Sized + Eq + Hash, T::Key: Borrow<Q>,

Gets a strong reference to the given key, if found.

Examples

use weak_table::WeakHashSet;
use std::rc::{Rc, Weak};
use std::ops::Deref;

let mut set: WeakHashSet<Weak<String>> = WeakHashSet::new();

let a = Rc::new("a".to_owned());
set.insert(a.clone());

let also_a = set.get("a").unwrap();

assert!(Rc::ptr_eq( &a, &also_a ));

expected O(1) time; worst-case O(p) time

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

Unconditionally inserts the value, returning the old value if already present. Does not replace the key.

expected O(1) time; worst-case O(p) time

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

where Q: ?Sized + Eq + Hash, T::Key: Borrow<Q>,

Removes the entry with the given key, if it exists, and returns the value.

expected O(1) time; worst-case O(p) time

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

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

Removes all mappings not satisfying the given predicate.

Also removes any expired mappings.

O(n) time

pub fn is_subset<S1>(&self, other: &WeakHashSet<T, S1>) -> bool

where S1: BuildHasher,

Is self a subset of other?

expected O(n) time; worst-case O(nq) time (where n is self.capacity() and q is the length of the probe sequences in other)

impl<T: WeakKey, S> WeakHashSet<T, S>

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

Gets an iterator over the keys and values.

O(1) time

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

Gets a draining iterator, which removes all the values but retains the storage.

O(1) time (and O(n) time to dispose of the result)

Trait Implementations

impl<T: Clone, S: Clone> Clone for WeakHashSet<T, S>

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

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: WeakKey, S> Debug for WeakHashSet<T, S>

where T::Strong: Debug,

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

Formats the value using the given formatter.

impl<T: WeakKey, S: BuildHasher + Default> Default for WeakHashSet<T, S>

fn default() -> Self

Returns the “default value” for a type.

impl<T: WeakKey, S: BuildHasher> Extend<<T as WeakElement>::Strong> for WeakHashSet<T, S>

fn extend<I: IntoIterator<Item = T::Strong>>(&mut self, iter: I)

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, S> FromIterator<<T as WeakElement>::Strong> for WeakHashSet<T, S>

where T: WeakKey, S: BuildHasher + Default,

fn from_iter<I: IntoIterator<Item = T::Strong>>(iter: I) -> Self

Creates a value from an iterator.

impl<'a, T: WeakKey, S> IntoIterator for &'a WeakHashSet<T, S>

fn into_iter(self) -> Self::IntoIter

Creates a borrowing iterator from self.

O(1) time

type Item = <T as WeakElement>::Strong

The type of the elements being iterated over.

type IntoIter = Iter<'a, T>

Which kind of iterator are we turning this into?

impl<T: WeakKey, S> IntoIterator for WeakHashSet<T, S>

fn into_iter(self) -> Self::IntoIter

Creates an owning iterator from self.

O(1) time (and O(n) time to dispose of the result)

type Item = <T as WeakElement>::Strong

The type of the elements being iterated over.

type IntoIter = IntoIter<T>

Which kind of iterator are we turning this into?

impl<T, S, S1> PartialEq<WeakHashSet<T, S1>> for WeakHashSet<T, S>

where T: WeakKey, S: BuildHasher, S1: BuildHasher,

fn eq(&self, other: &WeakHashSet<T, S1>) -> 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: WeakKey, S: BuildHasher> Eq for WeakHashSet<T, S>

where T::Key: Eq,