1import { Hashable } from "./Hashable";
 2
 3export class HashMap<K extends Hashable, V> implements Map<K, V> {
 4  static readonly EMPTY = Object.freeze(new HashMap());
 5  [Symbol.toStringTag]: "Map";
 6  private readonly keyMap = new Map<string, K>();
 7  private readonly valueMap = new Map<string, V>();
 8
 9  constructor(iterable?: Iterable<[K, V]>) {
10    if (iterable) {
11      for (const [key, value] of iterable) {
12        this.set(key, value);
13      }
14    }
15  }
16
17  get size() {
18    return this.valueMap.size;
19  }
20
21  clear(): void {
22    this.valueMap.clear();
23  }
24
25  delete(key: K): boolean {
26    this.keyMap.delete(key.hashKey);
27    return this.valueMap.delete(key.hashKey);
28  }
29
30  forEach(fn: (value: V, key: K, map: Map<K, V>) => void, thisArg?: any): void {
31    const self = this;
32    this.valueMap.forEach((value, key) => {
33      fn.bind(thisArg)(value, self.keyMap.get(key), self);
34    });
35  }
36
37  get(key: K): V | undefined {
38    return this.valueMap.get(key.hashKey);
39  }
40
41  has(key: K): boolean {
42    return this.keyMap.has(key.hashKey);
43  }
44
45  set(key: K, value: V): this {
46    this.keyMap.set(key.hashKey, key);
47    this.valueMap.set(key.hashKey, value);
48    return this;
49  }
50
51  [Symbol.iterator](): IterableIterator<[K, V]> {
52    const entries = this.valueMap.entries();
53    const keyMap = this.keyMap;
54    return {
55      next(): IteratorResult<[K, V]> {
56        const next = entries.next();
57        return {
58          done: next.done,
59          value: [keyMap.get(next.value[0]), next.value[1]],
60        };
61      },
62
63      [Symbol.iterator](): IterableIterator<[K, V]> {
64        return this;
65      },
66    };
67  }
68
69  *entries(): IterableIterator<[K, V]> {
70    for (const [hashKey, value] of this.valueMap.entries()) {
71      const key = this.keyMap.get(hashKey);
72      yield [key, value];
73    }
74  }
75
76  keys(): IterableIterator<K> {
77    return this.keyMap.values();
78  }
79
80  values(): IterableIterator<V> {
81    return this.valueMap.values();
82  }
83}