@graphql-hive/pubsub/dist/index.js

import { Repeater } from '@repeaterjs/repeater';
import { DisposableSymbols } from '@whatwg-node/disposablestack';
import { fakePromise } from '@whatwg-node/promise-helpers';

class MemPubSub {
  #disposed = false;
  #subscribers = /* @__PURE__ */ new Map();
  subscribedTopics() {
    return this.#subscribers.keys();
  }
  publish(topic, data) {
    if (this.#disposed) {
      throw new Error("PubSub is disposed, cannot publish data");
    }
    const listeners = this.#subscribers.get(topic);
    if (listeners) {
      for (const l of listeners.keys()) {
        l(data);
      }
    }
  }
  subscribe(topic, listener) {
    if (this.#disposed) {
      throw new Error("PubSub is disposed, cannot subscribe to topics");
    }
    let listeners = this.#subscribers.get(topic);
    if (!listeners) {
      listeners = /* @__PURE__ */ new Map();
      this.#subscribers.set(topic, listeners);
    }
    if (!listener) {
      return new Repeater((push, stop) => {
        listeners.set(push, stop);
        return stop.then(() => {
          listeners.delete(push);
          if (listeners.size === 0) {
            this.#subscribers.delete(topic);
          }
        });
      });
    }
    const listenerRef = new WeakRef(listener);
    const unsubscribe = () => {
      const l = listenerRef.deref();
      if (l) listeners.delete(l);
      if (listeners.size === 0) {
        this.#subscribers.delete(topic);
      }
    };
    listeners.set(listener, unsubscribe);
    return unsubscribe;
  }
  dispose() {
    this.#disposed = true;
    for (const sub of this.#subscribers.values()) {
      for (const stop of sub.values()) {
        stop();
      }
      sub.clear();
    }
    this.#subscribers.clear();
  }
  [DisposableSymbols.asyncDispose]() {
    return fakePromise(this.dispose());
  }
}

export { MemPubSub };