gristlabs_grist-core/app/client/lib/fromKoSave.ts

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/**
* Replicates some of grainjs's fromKo, except that the returned observables have a set() method
* which calls koObs.saveOnly(val) rather than koObs(val).
*/
import {IKnockoutObservable, KoWrapObs, Observable} from 'grainjs';
const wrappers: WeakMap<IKnockoutObservable<any>, Observable<any>> = new WeakMap();
/**
* Returns a Grain.js observable which mirrors a Knockout observable.
*
* Do not dispose this wrapper, as it is shared by all code using koObs, and its lifetime is tied
* to the lifetime of koObs. If unused, it consumes minimal resources, and should get garbage
* collected along with koObs.
*/
export function fromKoSave<T>(koObs: IKnockoutObservable<T>): Observable<T> {
return wrappers.get(koObs) || wrappers.set(koObs, new KoSaveWrapObs(koObs)).get(koObs)!;
}
export class KoSaveWrapObs<T> extends KoWrapObs<T> {
constructor(_koObs: IKnockoutObservable<T>) {
if (!('saveOnly' in _koObs)) {
throw new Error('fromKoSave needs a saveable observable');
}
super(_koObs);
}
public set(value: T): void {
// Hacky cast to get a private member. TODO: should make it protected instead.
(this as any)._koObs.saveOnly(value);
}
}