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Implement HashMap similar to Python's dict
Implement an abstract base class for values hashable by their numeric value and distinguishable by strict equality. Implement HashMap as an associative data structure for hashable values. Implement HashSet as a collection of hashable values. Replace FractionSet implementation with HashSet<Fraction>.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,201 @@ | ||
| /** | ||
| * A hashable type expected to remain immutable so that it can be used as a dictionary / hash map key. | ||
| */ | ||
| export abstract class Hashable { | ||
| abstract strictEquals(other: Hashable): boolean; | ||
|
|
||
| abstract valueOf(): number; | ||
| } | ||
|
|
||
| /** | ||
| * Python style dictionary implementation using hashable keys. | ||
| */ | ||
| export class HashMap<Key extends Hashable, Value> implements Map<Key, Value> { | ||
| private map: Map<number, [Key, Value][]>; | ||
|
|
||
| constructor(entries?: Iterable<[Key, Value]>) { | ||
| this.map = new Map(); | ||
| if (entries === undefined) { | ||
| return; | ||
| } | ||
| for (const [key, value] of entries) { | ||
| this.set(key, value); | ||
| } | ||
| } | ||
|
|
||
| set(key: Key, value: Value) { | ||
| const hash = key.valueOf(); | ||
| const subEntries = this.map.get(hash) ?? []; | ||
| for (let i = 0; i < subEntries.length; ++i) { | ||
| const [existing] = subEntries[i]; | ||
| if (key.strictEquals(existing)) { | ||
| subEntries[i] = [key, value]; | ||
| return this; | ||
| } | ||
| } | ||
| subEntries.push([key, value]); | ||
| this.map.set(hash, subEntries); | ||
| return this; | ||
| } | ||
|
|
||
| get(key: Key) { | ||
| const hash = key.valueOf(); | ||
| const subEntries = this.map.get(hash); | ||
| if (subEntries === undefined) { | ||
| return undefined; | ||
| } | ||
| for (const [existing, value] of subEntries) { | ||
| if (existing.strictEquals(key)) { | ||
| return value; | ||
| } | ||
| } | ||
| return undefined; | ||
| } | ||
|
|
||
| clear(): void { | ||
| this.map.clear(); | ||
| } | ||
|
|
||
| delete(key: Key): boolean { | ||
| const hash = key.valueOf(); | ||
| const subEntries = this.map.get(hash); | ||
| if (subEntries === undefined) { | ||
| return false; | ||
| } | ||
| for (let i = 0; i < subEntries.length; ++i) { | ||
| const [existing] = subEntries[i]; | ||
| if (existing.strictEquals(key)) { | ||
| subEntries.splice(i, 1); | ||
| if (!subEntries.length) { | ||
| this.map.delete(hash); | ||
| } | ||
| return true; | ||
| } | ||
| } | ||
| return false; | ||
| } | ||
|
|
||
| has(key: Key): boolean { | ||
| const hash = key.valueOf(); | ||
| const subEntries = this.map.get(hash); | ||
| if (subEntries === undefined) { | ||
| return false; | ||
| } | ||
| for (const [existing] of subEntries) { | ||
| if (existing.strictEquals(key)) { | ||
| return true; | ||
| } | ||
| } | ||
| return false; | ||
| } | ||
|
|
||
| get size(): number { | ||
| let total = 0; | ||
| for (const subEntries of this.map) { | ||
| total += subEntries.length; | ||
| } | ||
| return total; | ||
| } | ||
|
|
||
| *entries(): IterableIterator<[Key, Value]> { | ||
| for (const subEntries of this.map.values()) { | ||
| for (const entry of subEntries) { | ||
| yield entry; | ||
| } | ||
| } | ||
| } | ||
|
|
||
| *keys(): IterableIterator<Key> { | ||
| for (const subEntries of this.map.values()) { | ||
| for (const [key] of subEntries) { | ||
| yield key; | ||
| } | ||
| } | ||
| } | ||
|
|
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| *values(): IterableIterator<Value> { | ||
| for (const subEntries of this.map.values()) { | ||
| // eslint-disable-next-line @typescript-eslint/no-unused-vars | ||
| for (const [_, value] of subEntries) { | ||
| yield value; | ||
| } | ||
| } | ||
| } | ||
|
|
||
| *[Symbol.iterator]() { | ||
| yield* this.entries(); | ||
| } | ||
|
|
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| get [Symbol.toStringTag]() { | ||
| return 'HashMap'; | ||
| } | ||
|
|
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| forEach( | ||
| callbackfn: (value: Value, key: Key, map: HashMap<Key, Value>) => void, | ||
| thisArg?: any | ||
| ): void { | ||
| callbackfn = callbackfn.bind(thisArg); | ||
| for (const subEntries of this.map.values()) { | ||
| for (const [key, value] of subEntries) { | ||
| callbackfn(value, key, this); | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| /** | ||
| * Python style set implementation using hashable values. | ||
| */ | ||
| export class HashSet<T extends Hashable> implements Set<T> { | ||
| private hashmap: HashMap<T, undefined>; | ||
| constructor(values?: Iterable<T>) { | ||
| this.hashmap = new HashMap(); | ||
| if (values === undefined) { | ||
| return; | ||
| } | ||
| for (const value of values) { | ||
| this.hashmap.set(value, undefined); | ||
| } | ||
| } | ||
| add(value: T) { | ||
| this.hashmap.set(value, undefined); | ||
| return this; | ||
| } | ||
| clear(): void { | ||
| this.hashmap.clear(); | ||
| } | ||
| delete(value: T): boolean { | ||
| return this.hashmap.delete(value); | ||
| } | ||
| has(value: T): boolean { | ||
| return this.hashmap.has(value); | ||
| } | ||
| get size() { | ||
| return this.hashmap.size; | ||
| } | ||
| *entries(): IterableIterator<[T, T]> { | ||
| for (const key of this.hashmap.keys()) { | ||
| yield [key, key]; | ||
| } | ||
| } | ||
| *keys(): IterableIterator<T> { | ||
| yield* this.hashmap.keys(); | ||
| } | ||
| *values(): IterableIterator<T> { | ||
| yield* this.hashmap.keys(); | ||
| } | ||
| *[Symbol.iterator]() { | ||
| yield* this.hashmap.keys(); | ||
| } | ||
|
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| get [Symbol.toStringTag]() { | ||
| return 'HashSet'; | ||
| } | ||
| forEach( | ||
| callbackfn: (value: T, value2: T, set: Set<T>) => void, | ||
| thisArg?: any | ||
| ): void { | ||
| callbackfn = callbackfn.bind(thisArg); | ||
| this.hashmap.forEach((_, key) => callbackfn(key, key, this)); | ||
| } | ||
| } |
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