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// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.import { ERR_INVALID_ARG_TYPE } from "./internal/errors.ts";import { validateFunction } from "./internal/validators.mjs";import { nextTick } from "./process.ts";
type Subscriber = (message: unknown, name?: string) => void;
export class Channel {  _subscribers: Subscriber[];  name: string;  constructor(name: string) {    this._subscribers = [];    this.name = name;  }
  publish(message: unknown) {    for (const subscriber of this._subscribers) {      try {        subscriber(message, this.name);      } catch (err) {        nextTick(() => {          throw err;        });      }    }  }
  subscribe(subscription: Subscriber) {    validateFunction(subscription, "subscription");
    this._subscribers.push(subscription);  }
  unsubscribe(subscription: Subscriber) {    if (!this._subscribers.includes(subscription)) {      return false;    }
    this._subscribers.splice(this._subscribers.indexOf(subscription), 1);
    return true;  }
  get hasSubscribers() {    return this._subscribers.length > 0;  }}
const channels: Record<string, Channel> = {};
export function channel(name: string) {  if (typeof name !== "string" && typeof name !== "symbol") {    throw new ERR_INVALID_ARG_TYPE("channel", ["string", "symbol"], name);  }
  if (!Object.hasOwn(channels, name)) {    channels[name] = new Channel(name);  }
  return channels[name];}
export function hasSubscribers(name: string) {  if (!Object.hasOwn(channels, name)) {    return false;  }
  return channels[name].hasSubscribers;}
export function subscribe(name: string, subscription: Subscriber) {  const c = channel(name);
  return c.subscribe(subscription);}
export function unsubscribe(name: string, subscription: Subscriber) {  const c = channel(name);
  return c.unsubscribe(subscription);}
export default {  channel,  hasSubscribers,  subscribe,  unsubscribe,  Channel,};