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