Struct weak_table::WeakValueHashMap

pub struct WeakValueHashMap<K, V, S = RandomState> { /* fields omitted */ }

A hash map with weak values.

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

Methods

impl<K: Eq + Hash, V: WeakElement> WeakValueHashMap<K, V, RandomState>

pub fn new() -> Self

Creates an empty WeakValueHashMap.

pub fn with_capacity(capacity: usize) -> Self

Creates an empty WeakValueHashMap with the given capacity.

impl<K: Eq + Hash, V: WeakElement, S: BuildHasher> WeakValueHashMap<K, V, S>

pub fn with_hasher(hash_builder: S) -> Self

Creates an empty WeakValueHashMap with the given capacity and hasher.

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

Creates an empty WeakValueHashMap with the given capacity and hasher.

pub fn hasher(&self) -> &S

Returns a reference to the map's BuildHasher.

pub fn capacity(&self) -> usize

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

pub fn remove_expired(&mut self)

Removes all mappings whose keys have expired.

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

Reserves room for additional elements.

pub fn shrink_to_fit(&mut self)

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

pub fn len(&self) -> usize

Returns an over-approximation of the number of elements.

pub fn is_empty(&self) -> bool

Is the map empty?

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

pub fn load_factor(&self) -> f32

The proportion of buckets that are used.

This is an over-approximation because of expired keys.

pub fn entry(&mut self, key: K) -> Entry<K, V>

Gets the requested entry.

pub fn clear(&mut self)

Removes all associations from the map.

pub fn get<Q: ?Sized>(&self, key: &Q) -> Option<V::Strong> where
    Q: Hash + Eq,
    K: Borrow<Q>, 

Returns a reference to the value corresponding to the key.

pub fn contains_key<Q: ?Sized>(&self, key: &Q) -> bool where
    Q: Hash + Eq,
    K: Borrow<Q>, 

Returns true if the map contains the specified key.

pub fn insert(&mut self, key: K, value: V::Strong) -> Option<V::Strong>

Unconditionally inserts the value, returning the old value if already present.

Like std::collections::HashMap, this does not replace the key if occupied.

pub fn remove<Q: ?Sized>(&mut self, key: &Q) -> Option<V::Strong> where
    Q: Hash + Eq,
    K: Borrow<Q>, 

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

pub fn retain<F>(&mut self, f: F) where
    F: FnMut(&K, V::Strong) -> bool, 

Removes all mappings not satisfying the given predicate.

Also removes any expired mappings.

pub fn is_submap_with<F, S1, V1>(
    &self,
    other: &WeakValueHashMap<K, V1, S1>,
    value_equal: F
) -> bool where
    V1: WeakElement,
    F: FnMut(V::Strong, V1::Strong) -> bool,
    S1: BuildHasher, 

Is this map a submap of the other, using the given value comparison.

In particular, all the keys of self must be in other and the values must compare true with value_equal.

pub fn is_submap<V1, S1>(&self, other: &WeakValueHashMap<K, V1, S1>) -> bool where
    V1: WeakElement,
    V::Strong: PartialEq<V1::Strong>,
    S1: BuildHasher, 

Is self a submap of other?

pub fn domain_is_subset<V1, S1>(
    &self,
    other: &WeakValueHashMap<K, V1, S1>
) -> bool where
    V1: WeakElement,
    S1: BuildHasher, 

Are the keys of self a subset of the keys of other?

impl<K, V: WeakElement, S> WeakValueHashMap<K, V, S>

Important traits for Iter<'a, K, V>

impl<'a, K, V: WeakElement> Iterator for Iter<'a, K, V> type Item = (&'a K, V::Strong);

pub fn iter(&self) -> Iter<K, V>

Gets an iterator over the keys and values.

Important traits for Keys<'a, K, V>

impl<'a, K, V: WeakElement> Iterator for Keys<'a, K, V> type Item = &'a K;

pub fn keys(&self) -> Keys<K, V>

Gets an iterator over the keys.

Important traits for Values<'a, K, V>

impl<'a, K, V: WeakElement> Iterator for Values<'a, K, V> type Item = V::Strong;

pub fn values(&self) -> Values<K, V>

Gets an iterator over the values.

Important traits for Drain<'a, K, V>

impl<'a, K, V: WeakElement> Iterator for Drain<'a, K, V> type Item = (K, V::Strong);

pub fn drain(&mut self) -> Drain<K, V>

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

Trait Implementations

impl<K, V, V1, S, S1> PartialEq<WeakValueHashMap<K, V1, S1>> for WeakValueHashMap<K, V, S> where
    K: Eq + Hash,
    V: WeakElement,
    V1: WeakElement,
    V::Strong: PartialEq<V1::Strong>,
    S: BuildHasher,
    S1: BuildHasher, 

fn eq(&self, other: &WeakValueHashMap<K, V1, S1>) -> bool

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

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

This method tests for !=.

impl<K: Eq + Hash, V: WeakElement, S: BuildHasher> Eq for WeakValueHashMap<K, V, S> where
    V::Strong: Eq, 

impl<K: Eq + Hash, V: WeakElement, S: BuildHasher + Default> Default for WeakValueHashMap<K, V, S>

fn default() -> Self

Returns the "default value" for a type.

impl<K, V, S> FromIterator<(K, V::Strong)> for WeakValueHashMap<K, V, S> where
    K: Eq + Hash,
    V: WeakElement,
    S: BuildHasher + Default, 

fn from_iter<T: IntoIterator<Item = (K, V::Strong)>>(iter: T) -> Self

Creates a value from an iterator.

impl<K, V, S> Extend<(K, V::Strong)> for WeakValueHashMap<K, V, S> where
    K: Eq + Hash,
    V: WeakElement,
    S: BuildHasher, 

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

Extends a collection with the contents of an iterator.

impl<'a, K, V, S> Extend<(&'a K, &'a V::Strong)> for WeakValueHashMap<K, V, S> where
    K: 'a + Eq + Hash + Clone,
    V: 'a + WeakElement,
    V::Strong: Clone,
    S: BuildHasher, 

fn extend<T: IntoIterator<Item = (&'a K, &'a V::Strong)>>(&mut self, iter: T)

Extends a collection with the contents of an iterator.

impl<K: Debug, V: WeakElement, S> Debug for WeakValueHashMap<K, V, S> where
    V::Strong: Debug, 

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

Formats the value using the given formatter.

impl<K, V: WeakElement, S> IntoIterator for WeakValueHashMap<K, V, S>

type Item = (K, V::Strong)

The type of the elements being iterated over.

type IntoIter = IntoIter<K, V>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<'a, K, V: WeakElement, S> IntoIterator for &'a WeakValueHashMap<K, V, S>

type Item = (&'a K, V::Strong)

The type of the elements being iterated over.

type IntoIter = Iter<'a, K, V>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<K: Clone, V: Clone, S: Clone> Clone for WeakValueHashMap<K, V, S>

fn clone(&self) -> WeakValueHashMap<K, V, S>

Returns a copy of the value.

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

Performs copy-assignment from source.