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feat: support findLast
and reduceRight
methods (#9573)
* feat(collection): findLast and reverseRight * chore(collection): performance and tests change Co-authored-by: kyra <kyradiscord@gmail.com> * remove unnecessary code * Update packages/collection/src/collection.ts Co-authored-by: Aura Román <kyradiscord@gmail.com> * Apply suggestions from code review Co-authored-by: Jiralite <33201955+Jiralite@users.noreply.github.com> --------- Co-authored-by: kyra <kyradiscord@gmail.com> Co-authored-by: Jiralite <33201955+Jiralite@users.noreply.github.com>
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@ -908,3 +908,73 @@ describe('random thisArg tests', () => {
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}, array);
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});
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});
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describe('findLast() tests', () => {
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const coll = createTestCollection();
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test('it returns last matched element', () => {
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expect(coll.findLast((value) => value % 2 === 1)).toStrictEqual(3);
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});
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test('throws if fn is not a function', () => {
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// @ts-expect-error: Invalid function
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expectInvalidFunctionError(() => createCollection().findLast());
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// @ts-expect-error: Invalid function
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expectInvalidFunctionError(() => createCollection().findLast(123), 123);
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});
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test('binds the thisArg', () => {
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coll.findLast(function findLast() {
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expect(this).toBeNull();
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return true;
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}, null);
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});
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});
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describe('findLastKey() tests', () => {
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const coll = createTestCollection();
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test('it returns last matched element', () => {
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expect(coll.findLastKey((value) => value % 2 === 1)).toStrictEqual('c');
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});
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test('throws if fn is not a function', () => {
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// @ts-expect-error: Invalid function
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expectInvalidFunctionError(() => createCollection().findLastKey());
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// @ts-expect-error: Invalid function
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expectInvalidFunctionError(() => createCollection().findLastKey(123), 123);
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});
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test('binds the thisArg', () => {
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coll.findLastKey(function findLastKey() {
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expect(this).toBeNull();
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return true;
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}, null);
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});
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});
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describe('reduceRight() tests', () => {
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const coll = createTestCollection();
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test('throws if fn is not a function', () => {
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// @ts-expect-error: Invalid function
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expectInvalidFunctionError(() => coll.reduceRight());
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// @ts-expect-error: Invalid function
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expectInvalidFunctionError(() => coll.reduceRight(123), 123);
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});
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test('reduce collection into a single value with initial value', () => {
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const sum = coll.reduceRight((a, x) => a + x, 0);
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expect(sum).toStrictEqual(6);
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});
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test('reduce collection into a single value without initial value', () => {
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const sum = coll.reduceRight<number>((a, x) => a + x);
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expect(sum).toStrictEqual(6);
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});
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test('reduce empty collection without initial value', () => {
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const coll = createCollection();
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expect(() => coll.reduceRight((a: number, x) => a + x)).toThrowError(
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new TypeError('Reduce of empty collection with no initial value'),
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);
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});
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});
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@ -274,6 +274,64 @@ export class Collection<K, V> extends Map<K, V> {
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return undefined;
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}
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/**
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* Searches for a last item where the given function returns a truthy value. This behaves like
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* {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/findLast | Array.findLast()}.
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*
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* @param fn - The function to test with (should return a boolean)
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* @param thisArg - Value to use as `this` when executing the function
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*/
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public findLast<V2 extends V>(fn: (value: V, key: K, collection: this) => value is V2): V2 | undefined;
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public findLast(fn: (value: V, key: K, collection: this) => unknown): V | undefined;
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public findLast<This, V2 extends V>(
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fn: (this: This, value: V, key: K, collection: this) => value is V2,
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thisArg: This,
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): V2 | undefined;
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public findLast<This>(fn: (this: This, value: V, key: K, collection: this) => unknown, thisArg: This): V | undefined;
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public findLast(fn: (value: V, key: K, collection: this) => unknown, thisArg?: unknown): V | undefined {
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if (typeof fn !== 'function') throw new TypeError(`${fn} is not a function`);
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if (thisArg !== undefined) fn = fn.bind(thisArg);
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const entries = [...this.entries()];
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for (let index = entries.length - 1; index >= 0; index--) {
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const val = entries[index]![1];
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const key = entries[index]![0];
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if (fn(val, key, this)) return val;
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}
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return undefined;
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}
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/**
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* Searches for the key of a last item where the given function returns a truthy value. This behaves like
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* {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/findLastIndex | Array.findLastIndex()},
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* but returns the key rather than the positional index.
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*
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* @param fn - The function to test with (should return a boolean)
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* @param thisArg - Value to use as `this` when executing the function
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*/
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public findLastKey<K2 extends K>(fn: (value: V, key: K, collection: this) => key is K2): K2 | undefined;
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public findLastKey(fn: (value: V, key: K, collection: this) => unknown): K | undefined;
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public findLastKey<This, K2 extends K>(
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fn: (this: This, value: V, key: K, collection: this) => key is K2,
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thisArg: This,
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): K2 | undefined;
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public findLastKey<This>(
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fn: (this: This, value: V, key: K, collection: this) => unknown,
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thisArg: This,
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): K | undefined;
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public findLastKey(fn: (value: V, key: K, collection: this) => unknown, thisArg?: unknown): K | undefined {
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if (typeof fn !== 'function') throw new TypeError(`${fn} is not a function`);
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if (thisArg !== undefined) fn = fn.bind(thisArg);
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const entries = [...this.entries()];
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for (let index = entries.length - 1; index >= 0; index--) {
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const key = entries[index]![0];
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const val = entries[index]![1];
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if (fn(val, key, this)) return key;
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}
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return undefined;
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}
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/**
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* Removes items that satisfy the provided filter function.
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*
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@ -533,6 +591,37 @@ export class Collection<K, V> extends Map<K, V> {
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return accumulator;
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}
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/**
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* Applies a function to produce a single value. Identical in behavior to
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* {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduceRight | Array.reduceRight()}.
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*
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* @param fn - Function used to reduce, taking four arguments; `accumulator`, `value`, `key`, and `collection`
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* @param initialValue - Starting value for the accumulator
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*/
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public reduceRight<T>(fn: (accumulator: T, value: V, key: K, collection: this) => T, initialValue?: T): T {
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if (typeof fn !== 'function') throw new TypeError(`${fn} is not a function`);
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const entries = [...this.entries()];
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let accumulator!: T;
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let index: number;
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if (initialValue === undefined) {
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if (entries.length === 0) throw new TypeError('Reduce of empty collection with no initial value');
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accumulator = entries[entries.length - 1]![1] as unknown as T;
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index = entries.length - 1;
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} else {
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accumulator = initialValue;
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index = entries.length;
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}
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while (--index >= 0) {
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const key = entries[index]![0];
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const val = entries[index]![1];
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accumulator = fn(accumulator, val, key, this);
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}
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return accumulator;
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}
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/**
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* Identical to
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* {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/forEach | Map.forEach()},
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