Blame · immutableExt.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 type {ValueObject} from 'immutable';
b69ab31	9
b69ab31	10	const IS_RECORD_SYMBOL = '@@__IMMUTABLE_RECORD__@@';
b69ab31	11
b69ab31	12	/** Wraps a ValueObject so it self-updates on equals. */
b69ab31	13	export class SelfUpdate<T extends ValueObject> implements ValueObject {
b69ab31	14	inner: T;
b69ab31	15
b69ab31	16	/**
b69ab31	17	* Tell Recoil to not deepFreeze (Object.seal) this object. This is needed
b69ab31	18	* since we might update the `inner` field. We didn't break Recoil
b69ab31	19	* assumptions since we maintain the same "value" of the object.
b69ab31	20	*
b69ab31	21	* See https://github.com/facebookexperimental/Recoil/blob/0.7.7/packages/shared/util/Recoil_deepFreezeValue.js#L42
b69ab31	22	* Recoil tests `value[IS_RECORD_SYMBOL] != null`.
b69ab31	23	*
b69ab31	24	* For immutable.js, it actually checks the boolean value.
b69ab31	25	* See https://github.com/immutable-js/immutable-js/blob/v4.3.4/src/predicates/isRecord.js
b69ab31	26	* Immutable.js uses `Boolean(maybeRecord && maybeRecord[IS_RECORD_SYMBOL])`.
b69ab31	27	*
b69ab31	28	* By using `false`, this tricks Recoil to treat us as an immutable value,
b69ab31	29	* while does not break Immutable.js' type checking.
b69ab31	30	*/
b69ab31	31	[IS_RECORD_SYMBOL] = false;
b69ab31	32
b69ab31	33	constructor(inner: T) {
b69ab31	34	this.inner = inner;
b69ab31	35	}
b69ab31	36
b69ab31	37	hashCode(): number {
b69ab31	38	return this.inner.hashCode() + 1;
b69ab31	39	}
b69ab31	40
b69ab31	41	equals(other: unknown): boolean {
b69ab31	42	if (!(other instanceof SelfUpdate)) {
b69ab31	43	return false;
b69ab31	44	}
b69ab31	45	if (this === other) {
b69ab31	46	return true;
b69ab31	47	}
b69ab31	48	const otherInner = other.inner;
b69ab31	49	const result = this.inner.equals(otherInner);
b69ab31	50	if (result && this.inner !== otherInner) {
b69ab31	51	this.inner = otherInner;
b69ab31	52	}
b69ab31	53	return result;
b69ab31	54	}
b69ab31	55	}