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import { Lock } from "../../deps.ts";
export type SimplebusCallback<T> = (data: T) => void | Promise<void>;
export class Simplebus<T> {  _cbs: Set<SimplebusCallback<T>>;  _cbsOnce: Set<SimplebusCallback<T>>;  _lock: Lock<void>;  constructor() {    this._cbs = new Set<SimplebusCallback<T>>();    this._cbsOnce = new Set<SimplebusCallback<T>>();    this._lock = new Lock<void>();  }  async send(data: T, opts?: { useLock: boolean }): Promise<void> {    // useLock: default true    // To avoid deadlock, set useLock: false when you send from    // inside another event handler (on the same Simplebus instance)    let useLock = opts === undefined ? true : opts.useLock;    await this._lock.run(async () => {      for (let cb of this._cbs) {        await cb(data);      }      for (let cb of this._cbsOnce) {        await cb(data);      }      this._cbsOnce.clear();    }, { bypass: !useLock });  }  on(cb: SimplebusCallback<T>): () => void {    this._cbs.add(cb);    return () => this._cbs.delete(cb);  }  once(cb: SimplebusCallback<T>): () => void {    this._cbsOnce.add(cb);    return () => this._cbsOnce.delete(cb);  }  removeAllSubscribers() {    this._cbs.clear();    this._cbsOnce.clear();  }}