29 lines
734 B
TypeScript
29 lines
734 B
TypeScript
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export type Listener<T> = (event: T) => any;
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export class Emitter<T> {
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private listeners: {[key: string]: Listener<T>} = {};
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constructor() { }
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emit(e: T) {
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Object.values(this.listeners).forEach(l => l(e));
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}
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listen(fn: Listener<T>): () => {};
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listen(key: string, fn: Listener<T>): () => {};
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listen(keyOrFn: string | Listener<T>, fn?: Listener<T>): () => {} {
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const func: any = fn ? fn : keyOrFn;
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const key: string = typeof keyOrFn == 'string' ? keyOrFn :
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`_${Object.keys(this.listeners).length.toString()}`;
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this.listeners[<any>key] = func;
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return () => delete this.listeners[<any>key];
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}
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once(fn: Listener<T>) {
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const stop = this.listen(e => {
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fn(e);
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stop();
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});
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}
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}
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