49 lines
1.2 KiB
JavaScript
49 lines
1.2 KiB
JavaScript
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class Broker {
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constructor() {
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this.topics = {};
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}
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topics() {
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return Object.keys(this.topics);
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}
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subscribe(topic, listener) {
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let topics = this.topics;
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let channel = topics[topic];
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if (!channel) {
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channel = topics[topic] = [];
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}
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if (channel.indexOf(listener) < 0) {
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channel.push(listener);
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this.publish(".topic.add", topic);
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}
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}
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unsubscribe(topic, listener) {
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let channel = this.topics[topic];
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if (!channel) {
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return;
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}
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let index = channel.indexOf(listener);
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if (index < 0) {
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return;
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}
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channel.splice(index,1);
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if (channel.length === 0) {
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delete this.topics[topic];
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this.publish(".topic.remove", topic);
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}
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}
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publish(topic, message, options = {}) {
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if (topic !== ".topic.publish") {
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this.publish(".topic.publish", {topic, message, options});
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}
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let channel = this.topics[topic];
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if (channel && channel.length) {
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for (let listener of channel) {
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listener(message, topic, options);
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}
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}
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}
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}
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