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89 lines
2.6 KiB
89 lines
2.6 KiB
/**
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* An event bus can be used to emit events, and to subscribe to events
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* @constructor EventBus
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*/
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function EventBus() {
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this.subscriptions = [];
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}
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/**
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* Subscribe to an event
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* @param {String | RegExp} event The event can be a regular expression, or
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* a string with wildcards, like 'server.*'.
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* @param {function} callback. Callback are called with three parameters:
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* {String} event, {*} [data], {*} [source]
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* @param {*} [target]
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* @returns {String} id A subscription id
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*/
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EventBus.prototype.on = function (event, callback, target) {
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var regexp = (event instanceof RegExp) ?
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event :
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new RegExp(event.replace('*', '\\w+'));
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var subscription = {
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id: util.randomUUID(),
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event: event,
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regexp: regexp,
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callback: (typeof callback === 'function') ? callback : null,
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target: target
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};
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this.subscriptions.push(subscription);
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return subscription.id;
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};
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/**
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* Unsubscribe from an event
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* @param {String | Object} filter Filter for subscriptions to be removed
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* Filter can be a string containing a
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* subscription id, or an object containing
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* one or more of the fields id, event,
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* callback, and target.
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*/
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EventBus.prototype.off = function (filter) {
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var i = 0;
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while (i < this.subscriptions.length) {
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var subscription = this.subscriptions[i];
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var match = true;
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if (filter instanceof Object) {
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// filter is an object. All fields must match
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for (var prop in filter) {
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if (filter.hasOwnProperty(prop)) {
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if (filter[prop] !== subscription[prop]) {
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match = false;
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}
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}
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}
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}
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else {
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// filter is a string, filter on id
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match = (subscription.id == filter);
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}
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if (match) {
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this.subscriptions.splice(i, 1);
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}
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else {
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i++;
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}
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}
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};
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/**
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* Emit an event
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* @param {String} event
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* @param {*} [data]
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* @param {*} [source]
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*/
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EventBus.prototype.emit = function (event, data, source) {
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for (var i =0; i < this.subscriptions.length; i++) {
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var subscription = this.subscriptions[i];
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if (subscription.regexp.test(event)) {
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if (subscription.callback) {
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subscription.callback(event, data, source);
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}
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}
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}
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};
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