97 lines
2.8 KiB
JavaScript
97 lines
2.8 KiB
JavaScript
class Postie {
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constructor() {
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this._topics = new Map();
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}
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_getSubscribers(topic) {
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const subscribers = this._topics.get(topic);
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if (subscribers === undefined) {
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throw new Error(`Topic:"${topic}" doesn't exist.`);
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}
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return subscribers;
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}
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_getInboxes(topic, address) {
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const subscribers = this._getSubscribers(topic);
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const inboxes = subscribers.get(address);
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if (inboxes === undefined) {
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throw new Error(`Inbox on topic:"${topic}" at address:"${address}" doesn't exist.`);
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}
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return inboxes;
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}
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hasTopic(topic) {
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return this._topics.get(topic) !== undefined;
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}
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hasSubscriber(topic, address) {
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const subscribers = this._getSubscribers(topic);
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return subscribers.get(address) !== undefined;
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}
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hasTopicAndSubscriber(topic, address) {
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return (this.hasTopic(topic))
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? this.hasSubscriber(topic, address)
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: false;
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}
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/**
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* @param {string} topic - Subscription topic
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* @param {string} address - Address of subscriber
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* @param {function} inbox - The inbox function to receive post data
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*/
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subscribe(topic, address, inbox) {
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if (typeof inbox !== 'function') {
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throw new TypeError('Inbox must be a function.');
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}
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if (this._topics.has(topic) === false) {
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this._topics.set(topic, new Map());
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}
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const subscribers = this._topics.get(topic);
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const inboxes = subscribers.get(address) ?? new Set();
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inboxes.add(inbox);
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subscribers.set(address, inboxes);
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return () => this.unsubscribe(topic, address, inbox);
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}
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unsubscribe(topic, address, inbox) {
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const subscribers = this._getSubscribers(topic);
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if (!subscribers) throw new Error(`Unable to unsubscribe. Topic: "${topic}" doesn't exist.`);
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const inboxes = subscribers.get(address);
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if (!inboxes) throw new Error(`Unable to unsubscribe. Subscriber on topic:"${topic}" at address:"${address}" doesn't exist`);
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if (!inboxes.delete(inbox)) throw new Error('Unable to unsubscribe. Inbox doesn\'t exist');
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if (inboxes.size === 0) subscribers.delete(address);
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if (subscribers.size === 0) this._topics.delete(topic);
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}
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/**
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* @param {string} topic - Subscription topic
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* @param {string|string[]} address - Address of subscriber
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* @param {*} data - Data to deliver to subscriber
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*/
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post(topic, address, data) {
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const sendPost = (inboxes, addr) => {
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if (inboxes === undefined) {
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throw new Error(`Unable to post on topic:"${topic}" at address:"${addr}". Subscriber doesn't exist.`);
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}
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inboxes.forEach((inbox) => inbox(data));
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};
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if (typeof address === 'string') {
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sendPost(this._getInboxes(topic, address), address);
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return;
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}
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const subscribers = this._getSubscribers(topic);
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address.forEach((addr) => {
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sendPost(subscribers.get(addr), addr);
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});
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}
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}
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export default Postie;
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