Blame · deepEqualExt.ts

b69ab31	1	/**
b69ab31	2	* Copyright (c) Meta Platforms, Inc. and affiliates.
b69ab31	3	*
b69ab31	4	* This source code is licensed under the MIT license found in the
b69ab31	5	* LICENSE file in the root directory of this source tree.
b69ab31	6	*/
b69ab31	7
b69ab31	8	import deepEqual from 'fast-deep-equal';
b69ab31	9
b69ab31	10	/** Try to reuse objects from `oldArray` for objects with the same key and deepEqual values. */
b69ab31	11	export function reuseEqualObjects<T>(
b69ab31	12	oldArray: Array<T>,
b69ab31	13	newArray: Array<T>,
b69ab31	14	keyFunc: (value: T) => string,
b69ab31	15	equalFunc: (a: T, b: T) => boolean = deepEqual,
b69ab31	16	): Array<T> {
b69ab31	17	const oldMap = new Map<string, T>(oldArray.map(v => [keyFunc(v), v]));
b69ab31	18	return newArray.map(value => {
b69ab31	19	const oldValue = oldMap.get(keyFunc(value));
b69ab31	20	return oldValue && equalFunc(oldValue, value) ? oldValue : value;
b69ab31	21	});
b69ab31	22	}