/**
* Representation of a single EventEmitter function.
* @private
*/
class EE {
/**
* @param {function} fn Event handler to be called.
* @param {Mixed} context Context for function execution.
* @param {boolean} once Only emit once
* @private
*/
constructor(fn, context, once = false) {
this.fn = fn;
this.context = context;
this.once = once;
}
}
/**
* Minimal EventEmitter interface that is molded against the Node.js
* EventEmitter interface.
*
* @class EventEmitter
*/
class EventEmitter {
/**
* @constructor
*/
constructor() {
/**
* Holds the assigned EventEmitters by name.
*
* @type {object}
* @private
*/
this._events = undefined;
}
/**
* Return a list of assigned event listeners.
*
* @memberof EventEmitter#
* @method listeners
* @param {string} event The events that should be listed.
* @param {boolean} exists We only need to know if there are listeners.
* @returns {array|boolean} Listener list
*/
listeners(event, exists) {
let available = this._events && this._events[event];
if (exists) {return !!available;}
if (!available) {return [];}
if (available.fn) {return [available.fn];}
let i, l, ee;
for (i = 0, l = available.length, ee = new Array(l); i < l; i++) {
ee[i] = available[i].fn;
}
return ee;
}
/**
* Emit an event to all registered event listeners.
*
* @memberof EventEmitter#
* @method emit
* @param {string} event The name of the event.
* @param {*} a1 First param
* @param {*} a2 Second param
* @param {*} a3 Third param
* @param {*} a4 Forth param
* @param {*} a5 Fifth param
* @returns {boolean} Indication if we've emitted an event.
*/
emit(event, a1, a2, a3, a4, a5) {
if (!this._events || !this._events[event]) {return false;}
let listeners = this._events[event],
len = arguments.length, args, i;
if ('function' === typeof listeners.fn) {
if (listeners.once) {this.removeListener(event, listeners.fn, undefined, true);}
switch (len) {
case 1: return listeners.fn.call(listeners.context), true;
case 2: return listeners.fn.call(listeners.context, a1), true;
case 3: return listeners.fn.call(listeners.context, a1, a2), true;
case 4: return listeners.fn.call(listeners.context, a1, a2, a3), true;
case 5: return listeners.fn.call(listeners.context, a1, a2, a3, a4), true;
case 6: return listeners.fn.call(listeners.context, a1, a2, a3, a4, a5), true;
}
for (i = 1, args = new Array(len - 1); i < len; i++) {
args[i - 1] = arguments[i];
}
listeners.fn.apply(listeners.context, args);
}
else {
let length = listeners.length, j;
for (i = 0; i < length; i++) {
if (listeners[i].once) {this.removeListener(event, listeners[i].fn, undefined, true);}
switch (len) {
case 1: listeners[i].fn.call(listeners[i].context); break;
case 2: listeners[i].fn.call(listeners[i].context, a1); break;
case 3: listeners[i].fn.call(listeners[i].context, a1, a2); break;
default:
if (!args) {
for (j = 1, args = new Array(len - 1); j < len; j++) {
args[j - 1] = arguments[j];
}}
listeners[i].fn.apply(listeners[i].context, args);
}
}
}
return true;
}
/**
* Register a new EventListener for the given event.
*
* @memberof EventEmitter#
* @method on
* @param {string} event Name of the event.
* @param {functon} fn Callback function.
* @param {Mixed} context The context of the function.
* @return {EventEmitter} Self for chaining
*/
on(event, fn, context) {
var listener = new EE(fn, context || this);
if (!this._events) {this._events = Object.create(null);}
if (!this._events[event]) {this._events[event] = listener;}
else {
if (!this._events[event].fn) {this._events[event].push(listener);}
else {
this._events[event] = [
this._events[event], listener,
];}
}
return this;
}
/**
* Add an EventListener that's only called once.
*
* @memberof EventEmitter#
* @method once
* @param {string} event Name of the event.
* @param {function} fn Callback function.
* @param {Mixed} context The context of the function.
* @return {EventEmitter} Self for chaining
*/
once(event, fn, context) {
let listener = new EE(fn, context || this, true);
if (!this._events) {this._events = Object.create(null);}
if (!this._events[event]) {this._events[event] = listener;}
else {
if (!this._events[event].fn) {this._events[event].push(listener);}
else {
this._events[event] = [
this._events[event], listener,
];}
}
return this;
}
/**
* Remove event listeners.
*
* @memberof EventEmitter#
* @method removeListener
* @param {string} event The event we want to remove.
* @param {function} fn The listener that we need to find.
* @param {Mixed} context Only remove listeners matching this context.
* @param {boolean} once Only remove once listeners.
* @return {EventEmitter} Self for chaining
*/
removeListener(event, fn, context, once) {
if (!this._events || !this._events[event]) {return this;}
let listeners = this._events[event], events = [];
if (fn) {
if (listeners.fn) {
if (
listeners.fn !== fn
|| (once && !listeners.once)
|| (context && listeners.context !== context)
) {
events.push(listeners);
}
}
else {
for (let i = 0, length = listeners.length; i < length; i++) {
if (
listeners[i].fn !== fn
|| (once && !listeners[i].once)
|| (context && listeners[i].context !== context)
) {
events.push(listeners[i]);
}
}
}
}
//
// Reset the array, or remove it completely if we have no more listeners.
//
if (events.length) {
this._events[event] = events.length === 1 ? events[0] : events;
}
else {
delete this._events[event];
}
return this;
}
/**
* Remove all listeners or only the listeners for the specified event.
*
* @memberof EventEmitter#
* @method removeAllListeners
* @param {string} event The event want to remove all listeners for.
* @return {EventEmitter} Self for chaining
*/
removeAllListeners(event) {
if (!this._events) {return this;}
if (event) {delete this._events[event];}
else {this._events = Object.create(null);}
return this;
}
}
/**
* @method off
* @memberof EventEmitter#
* @alias EventEmitter#removeListener
*/
EventEmitter.prototype.off = EventEmitter.prototype.removeListener;
/**
* @method addListener
* @memberof EventEmitter#
* @alias EventEmitter#on
*/
EventEmitter.prototype.addListener = EventEmitter.prototype.on;
/**
* Minimal EventEmitter interface that is molded against the Node.js
* EventEmitter interface.
*
* @exports engine/EventEmitter
* @see EventEmitter
*/
module.exports = EventEmitter;