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/*
* This file is part of Adblock Plus <https://adblockplus.org/>,
* Copyright (C) 2006-2017 eyeo GmbH
*
* Adblock Plus is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* Adblock Plus is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Adblock Plus. If not, see <http://www.gnu.org/licenses/>.
*/
"use strict";
/**
* Registers and emits named events.
*
* @constructor
*/
exports.EventEmitter = function()
{
this._listeners = Object.create(null);
};
exports.EventEmitter.prototype = {
/**
* Adds a listener for the specified event name.
*
* @param {string} name
* @param {function} listener
*/
on(name, listener)
{
if (name in this._listeners)
this._listeners[name].push(listener);
else
this._listeners[name] = [listener];
},
/**
* Removes a listener for the specified event name.
*
* @param {string} name
* @param {function} listener
*/
off(name, listener)
{
let listeners = this._listeners[name];
if (listeners)
{
let idx = listeners.indexOf(listener);
if (idx != -1)
listeners.splice(idx, 1);
}
},
/**
* Adds a one time listener and returns a promise that
* is resolved the next time the specified event is emitted.
* @param {string} name
* @return {Promise}
*/
once(name)
{
return new Promise(resolve =>
{
let listener = () =>
{
this.off(name, listener);
resolve();
};
this.on(name, listener);
});
},
/**
* Returns a copy of the array of listeners for the specified event.
*
* @param {string} name
* @return {function[]}
*/
listeners(name)
{
let listeners = this._listeners[name];
return listeners ? listeners.slice() : [];
},
/**
* Calls all previously added listeners for the given event name.
*
* @param {string} name
* @param {...*} [arg]
*/
emit(name, ...args)
{
let listeners = this.listeners(name);
for (let listener of listeners)
listener(...args);
}
};
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