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/**
* Copyright © Magento, Inc. All rights reserved.
* See COPYING.txt for license details.
*/
define([
'ko',
'underscore'
], function (ko, _) {
'use strict';
var eventsMap = new WeakMap();
/**
* Returns events map or a specific event
* data associated with a provided object.
*
* @param {Object} obj - Key in the events weakmap.
* @param {String} [name] - Name of the event.
* @returns {Map|Array|Boolean}
*/
function getEvents(obj, name) {
var events = eventsMap.get(obj);
if (!events) {
return false;
}
return name ? events.get(name) : events;
}
/**
* Adds new event handler.
*
* @param {Object} obj - Key in the events weakmap.
* @param {String} ns - Callback namespace.
* @param {Function} callback - Event callback.
* @param {String} name - Name of the event.
*/
function addHandler(obj, ns, callback, name) {
var events = getEvents(obj),
observable,
data;
observable = !ko.isObservable(obj[name]) ?
ko.getObservable(obj, name) :
obj[name];
if (observable) {
observable.subscribe(callback);
return;
}
if (!events) {
events = new Map();
eventsMap.set(obj, events);
}
data = {
callback: callback,
ns: ns
};
events.has(name) ?
events.get(name).push(data) :
events.set(name, [data]);
}
/**
* Invokes provided callbacks with a specified arguments.
*
* @param {Array} handlers
* @param {Array} args
* @returns {Boolean}
*/
function trigger(handlers, args) {
var bubble = true,
callback;
handlers.forEach(function (handler) {
callback = handler.callback;
if (callback.apply(null, args) === false) {
bubble = false;
}
});
return bubble;
}
return {
/**
* Calls callback when name event is triggered.
* @param {String} events
* @param {Function} callback
* @param {Function} ns
* @return {Object} reference to this
*/
on: function (events, callback, ns) {
var iterator;
if (arguments.length < 2) {
ns = callback;
}
iterator = addHandler.bind(null, this, ns);
_.isObject(events) ?
_.each(events, iterator) :
iterator(callback, events);
return this;
},
/**
* Removed callback from listening to target event
* @param {String} ns
* @return {Object} reference to this
*/
off: function (ns) {
var storage = getEvents(this);
if (!storage) {
return this;
}
storage.forEach(function (handlers, name) {
handlers = handlers.filter(function (handler) {
return !ns ? false : handler.ns !== ns;
});
handlers.length ?
storage.set(name, handlers) :
storage.delete(name);
});
return this;
},
/**
* Triggers event and executes all attached callbacks.
*
* @param {String} name - Name of the event to be triggered.
* @returns {Boolean}
*/
trigger: function (name) {
var handlers,
args;
handlers = getEvents(this, name),
args = _.toArray(arguments).slice(1);
if (!handlers || !name) {
return true;
}
return trigger(handlers, args);
}
};
});