smartstate/ts/smartstate.classes.statepart.ts

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import * as plugins from './smartstate.plugins.js';
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import { StateAction, type IActionDef } from './smartstate.classes.stateaction.js';
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export class StatePart<TStatePartName, TStatePayload> {
public name: TStatePartName;
public state = new plugins.smartrx.rxjs.Subject<TStatePayload>();
public stateStore: TStatePayload;
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private cumulativeDeferred = plugins.smartpromise.cumulativeDefer();
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constructor(nameArg: TStatePartName) {
this.name = nameArg;
}
/**
* gets the state from the state store
*/
public getState(): TStatePayload {
return this.stateStore;
}
/**
* sets the stateStore to the new state
* @param newStateArg
*/
public setState(newStateArg: TStatePayload) {
this.stateStore = newStateArg;
this.notifyChange();
}
/**
* notifies of a change on the state
*/
public notifyChange() {
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const createStateHash = (stateArg: any) => {
return plugins.isohash.sha256FromString(plugins.smartjson.stringify(stateArg));
};
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if (
this.stateStore &&
this.lastStateNotificationPayloadHash &&
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createStateHash(this.stateStore) === this.lastStateNotificationPayloadHash
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) {
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return;
} else {
this.lastStateNotificationPayloadHash = this.stateStore;
}
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this.state.next(this.stateStore);
}
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private lastStateNotificationPayloadHash: any;
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/**
* creates a cumulative notification by adding a change notification at the end of the call stack;
*/
public notifyChangeCumulative() {
// TODO: check viability
setTimeout(() => this.state.next(this.stateStore), 0);
}
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/**
* selects a state or a substate
*/
public select<T = TStatePayload>(
selectorFn?: (state: TStatePayload) => T
): plugins.smartrx.rxjs.Observable<T> {
if (!selectorFn) {
selectorFn = (state: TStatePayload) => <T>(<any>state);
}
const mapped = this.state.pipe(
plugins.smartrx.rxjs.ops.startWith(this.getState()),
plugins.smartrx.rxjs.ops.map((stateArg) => {
try {
return selectorFn(stateArg);
} catch (e) {
// Nothing here
}
})
);
return mapped;
}
/**
* creates an action capable of modifying the state
*/
public createAction<TActionPayload>(
actionDef: IActionDef<TStatePayload, TActionPayload>
): StateAction<TStatePayload, TActionPayload> {
return new StateAction(this, actionDef);
}
/**
* dispatches an action on the statepart level
*/
public async dispatchAction<T>(stateAction: StateAction<TStatePayload, T>, actionPayload: T) {
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await this.cumulativeDeferred.promise;
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const newState = await stateAction.actionDef(this, actionPayload);
this.setState(newState);
}
/**
* waits until a certain part of the state becomes available
* @param selectorFn
*/
public async waitUntilPresent<T = TStatePayload>(
selectorFn?: (state: TStatePayload) => T
): Promise<T> {
const done = plugins.smartpromise.defer<T>();
const selectedObservable = this.select(selectorFn);
const subscription = selectedObservable.subscribe(async (value) => {
if (value) {
done.resolve(value);
}
});
const result = await done.promise;
subscription.unsubscribe();
return result;
}
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/**
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* is executed
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*/
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public async stateSetup(
funcArg: (statePartArg?: StatePart<any, TStatePayload>) => Promise<TStatePayload>
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) {
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const resultPromise = funcArg(this);
this.cumulativeDeferred.addPromise(resultPromise);
this.setState(await resultPromise);
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}
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}