Struct UnorderedHashMap

pub struct UnorderedHashMap<Key, Value, BH = RandomState>(/* private fields */);

A hash map that does not care about the order of insertion.

In particular, it does not support iterating, in order to guarantee deterministic compilation. It does support aggregation which can be used in intermediate computations (see aggregate_by). For an iterable version see OrderedHashMap.

Implementations

impl<Key, Value, BH> UnorderedHashMap<Key, Value, BH>

pub fn len(&self) -> usize

Returns the number of elements in the map.

pub fn is_empty(&self) -> bool

Returns true if the map contains no elements.

impl<Key: Eq + Hash, Value, BH: BuildHasher> UnorderedHashMap<Key, Value, BH>

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

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

Returns a reference to the value corresponding to the key.

The key may be any borrowed form of the map’s key type, but Hash and Eq on the borrowed form must match those for the key type.

pub fn get_mut<Q>(&mut self, key: &Q) -> Option<&mut Value>

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

Returns a mutable reference to the value corresponding to the key.

The key may be any borrowed form of the map’s key type, but Hash and Eq on the borrowed form must match those for the key type.

pub fn insert(&mut self, key: Key, value: Value) -> Option<Value>

Inserts a key-value pair into the map.

If the map did not have this key present, None is returned.

If the map did have this key present, the value is updated, and the old value is returned. The key is not updated, though; this matters for types that can be == without being identical.

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

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

Removes a key from the map, returning the value at the key if the key was previously in the map.

The key may be any borrowed form of the map’s key type, but Hash and Eq on the borrowed form must match those for the key type.

pub fn entry(&mut self, key: Key) -> Entry<'_, Key, Value>

Gets the given key’s corresponding entry in the map for in-place manipulation.

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

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

Returns true if the map contains a value for the specified key.

pub fn map<TargetValue>( &self, mapper: impl Fn(&Value) -> TargetValue, ) -> UnorderedHashMap<Key, TargetValue, BH>

where Key: Clone, BH: Clone,

Maps the values of the map to new values using the given function.

pub fn aggregate_by<TargetKey: Eq + Hash, TargetValue>( &self, mapping_function: impl Fn(&Key) -> TargetKey, reduce_function: impl Fn(&TargetValue, &Value) -> TargetValue, default_value: &TargetValue, ) -> UnorderedHashMap<TargetKey, TargetValue, BH>

where BH: Clone,

Aggregates values of the map using the given functions. mapping_function maps each key to a new key, possibly mapping multiple original keys to the same target key. reduce_function dictates how to aggregate any two values of the same target key. default_value is the initial value for each target key. Note! as the map is unordered, reduce_function should be commutative. Otherwise, the result is undefined (nondeterministic).

pub fn iter_sorted(&self) -> impl Iterator<Item = (&Key, &Value)>

where Key: Ord,

Iterates the map in an ascending order applied by the Ord implementation of Key. NOTE! To guarantee a deterministic output, the Ord implementation must apply a strict ordering. That is, a <= b and b <= a, then a == b. If Ord is derived (in all hierarchy levels), this is probably the case. If the ordering is not strict, the order of the output OrderedHashMap is undefined (nondeterministic). This can be used to convert an unordered map to an ordered map (mostly when the unordered map was used for intermediate processing).

pub fn into_iter_sorted(self) -> impl Iterator<Item = (Key, Value)>

where Key: Ord + Clone,

A consuming version of iter_sorted.

pub fn iter_sorted_by_key<TargetKey, F>(&self, f: F) -> IntoIter<(&Key, &Value)>

where TargetKey: Ord, F: FnMut(&(&Key, &Value)) -> TargetKey,

Iterates the map in an ascending order of the keys produced by the given function f. NOTE! To guarantee a deterministic output, f’s implementation must apply a strict ordering of the (Key, Value) pairs. That is, for any given pair of entries a=(k_a, v_a) and b=(k_b, v_b), if a <= b and b <= a, then a == b. If the ordering is not strict, the order of the output OrderedHashMap is undefined (nondeterministic). This can be used to convert an unordered map to an ordered map (mostly when the unordered map was used for intermediate processing).

pub fn into_iter_sorted_by_key<TargetKey, F>( self, f: F, ) -> IntoIter<(Key, Value)>

where TargetKey: Ord, F: FnMut(&(Key, Value)) -> TargetKey,

A consuming version of iter_sorted_by_key.

pub fn filter<P>(self, p: P) -> Self

where BH: Default, P: FnMut(&Key, &Value) -> bool,

Creates a new map with only the elements from the original map for which the given predicate returns true. Consuming.

pub fn filter_cloned<P>(&self, p: P) -> Self

where BH: Default, P: FnMut(&Key, &Value) -> bool, Key: Clone, Value: Clone,

Non consuming version of filter. Only clones the filtered entries. Requires Key and Value to implement Clone.

pub fn merge<HandleDuplicate>( &mut self, other: &Self, handle_duplicate: HandleDuplicate, )

where BH: Clone, HandleDuplicate: Fn(OccupiedEntry<'_, Key, Value>, &Value), Key: Clone, Value: Clone,

Merges the map with another map. If a key is present in both maps, the given handler function is used to combine the values.

Trait Implementations

impl<Key: Clone, Value: Clone, BH: Clone> Clone for UnorderedHashMap<Key, Value, BH>

fn clone(&self) -> UnorderedHashMap<Key, Value, BH>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<Key: Debug, Value: Debug, BH: Debug> Debug for UnorderedHashMap<Key, Value, BH>

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

Formats the value using the given formatter.

impl<Key, Value, BH: Default> Default for UnorderedHashMap<Key, Value, BH>

fn default() -> Self

Returns the “default value” for a type.

impl<Key: Hash + Eq, Value, const N: usize, BH: BuildHasher + Default> From<[(Key, Value); N]> for UnorderedHashMap<Key, Value, BH>

fn from(items: [(Key, Value); N]) -> Self

Converts to this type from the input type.

impl<Key: Hash + Eq, Value, BH: BuildHasher + Default> FromIterator<(Key, Value)> for UnorderedHashMap<Key, Value, BH>

fn from_iter<T: IntoIterator<Item = (Key, Value)>>(iter: T) -> Self

Creates a value from an iterator.

impl<Key, Q, Value, BH: BuildHasher> Index<&Q> for UnorderedHashMap<Key, Value, BH>

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

type Output = Value

The returned type after indexing.

fn index(&self, key: &Q) -> &Self::Output

Performs the indexing (container[index]) operation.

impl<Key, Value, BH> PartialEq for UnorderedHashMap<Key, Value, BH>

where Key: Eq + Hash, Value: PartialEq, BH: BuildHasher,

fn eq(&self, other: &Self) -> 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<Key, Value, BH> Eq for UnorderedHashMap<Key, Value, BH>

where Key: Eq + Hash, Value: Eq, BH: BuildHasher,