HashMap

Mutable hash map (aka Hashtable)

This module defines an imperative hash map (hash table), with a general key and value type.

It has a minimal object-oriented interface: get, set, delete, count and entries.

The class is parameterized by the key’s equality and hash functions, and an initial capacity. However, as with the Buffer class, no array allocation happens until the first set.

Internally, table growth policy is very simple, for now: Double the current capacity when the expected bucket list size grows beyond a certain constant.

HashMap

class HashMap<K, V>(initCapacity : Nat, keyEq : (K, K) -> Bool, keyHash : K -> Hash.Hash)

An imperative HashMap with a minimal object-oriented interface. Maps keys of type K to values of type V.

size

func size() : Nat

Returns the number of entries in this HashMap.

delete

func delete(k : K)

Deletes the entry with the key k. Doesn’t do anything if the key doesn’t exist.

remove

func remove(k : K) : ?V

Removes the entry with the key k and returns the associated value if it existed or null otherwise.

get

func get(k : K) : ?V

Gets the entry with the key k and returns its associated value if it existed or null otherwise.

put

func put(k : K, v : V)

Insert the value v at key k. Overwrites an existing entry with key k

replace

func replace(k : K, v : V) : ?V

Insert the value v at key k and returns the previous value stored at k or null if it didn’t exist.

entries

func entries() : Iter.Iter<(K, V)>

Returns an iterator over the key value pairs in this HashMap. Does not modify the HashMap.

clone

func clone<K, V>(h : HashMap<K, V>, keyEq : (K, K) -> Bool, keyHash : K -> Hash.Hash) : HashMap<K, V>

clone cannot be an efficient object method, …​but is still useful in tests, and beyond.

fromIter

func fromIter<K, V>(iter : Iter.Iter<(K, V)>, initCapacity : Nat, keyEq : (K, K) -> Bool, keyHash : K -> Hash.Hash) : HashMap<K, V>

Clone from any iterator of key-value pairs

map

func map<K, V1, V2>(h : HashMap<K, V1>, keyEq : (K, K) -> Bool, keyHash : K -> Hash.Hash, mapFn : (K, V1) -> V2) : HashMap<K, V2>

mapFilter

func mapFilter<K, V1, V2>(h : HashMap<K, V1>, keyEq : (K, K) -> Bool, keyHash : K -> Hash.Hash, mapFn : (K, V1) -> ?V2) : HashMap<K, V2>