alistair/dist/bus/index.js

import { StrictMap } from '../chunk-JMMXLLD5.js';

// Copyright 2026 Alistair Smith https://github.com/alii/alistair

// src/bus/index.ts
var EventBus = class {
  listeners;
  constructor() {
    this.listeners = new StrictMap();
  }
  on(key, listener) {
    const list = this.listeners.getOr(key, () => /* @__PURE__ */ new Set());
    list.add(listener);
    return () => {
      this.off(key, listener);
    };
  }
  off(key, listener) {
    const list = this.listeners.getElse(key, () => null);
    if (!list) {
      return;
    }
    list.delete(listener);
    if (list.size === 0) {
      this.listeners.delete(key);
    }
  }
  emit(key, ...args) {
    const listeners = this.listeners.getElse(key, () => null);
    if (!listeners) {
      return;
    }
    for (const listener of listeners) {
      listener(...args);
    }
  }
};

export { EventBus };