mapcomplete/UI/UIEventSource.ts

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export class UIEventSource<T>{
public data : T;
private _callbacks = [];
constructor(data: T) {
this.data = data;
}
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public addCallback(callback: ((latestData : T) => void)) {
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this._callbacks.push(callback);
return this;
}
public setData(t: T): void {
if (this.data === t) {
return;
}
this.data = t;
this.ping();
}
public ping(): void {
for (const callback of this._callbacks) {
callback(this.data);
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}
}
public map<J>(f: ((T) => J)): UIEventSource<J> {
const self = this;
this.addCallback(function () {
newSource.setData(f(self.data));
newSource.ping();
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});
const newSource = new UIEventSource<J>(
f(this.data)
);
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return newSource;
}
}