gecko-dev/browser/devtools/shared/EventEmitter.jsm

81 строка
2.4 KiB
JavaScript

var EXPORTED_SYMBOLS = ["EventEmitter"];
function EventEmitter() {
}
EventEmitter.prototype = {
/**
* Connect a listener.
*
* @param string aEvent
* The event name to which we're connecting.
* @param function aListener
* Called when the event is fired.
*/
on: function EventEmitter_on(aEvent, aListener) {
if (!this._eventEmitterListeners)
this._eventEmitterListeners = new Map();
if (!this._eventEmitterListeners.has(aEvent)) {
this._eventEmitterListeners.set(aEvent, []);
}
this._eventEmitterListeners.get(aEvent).push(aListener);
},
/**
* Listen for the next time an event is fired.
*
* @param string aEvent
* The event name to which we're connecting.
* @param function aListener
* Called when the event is fired. Will be called at most one time.
*/
once: function EventEmitter_once(aEvent, aListener) {
let handler = function() {
this.off(aEvent, handler);
aListener();
}.bind(this);
this.on(aEvent, handler);
},
/**
* Remove a previously-registered event listener. Works for events
* registered with either on or once.
*
* @param string aEvent
* The event name whose listener we're disconnecting.
* @param function aListener
* The listener to remove.
*/
off: function EventEmitter_off(aEvent, aListener) {
if (!this._eventEmitterListeners)
return;
let listeners = this._eventEmitterListeners.get(aEvent);
this._eventEmitterListeners.set(aEvent, listeners.filter(function(l) aListener != l));
},
/**
* Emit an event. All arguments to this method will
* be sent to listner functions.
*/
emit: function EventEmitter_emit(aEvent) {
if (!this._eventEmitterListeners || !this._eventEmitterListeners.has(aEvent))
return;
let originalListeners = this._eventEmitterListeners.get(aEvent);
for (let listener of this._eventEmitterListeners.get(aEvent)) {
// If the object was destroyed during event emission, stop
// emitting.
if (!this._eventEmitterListeners) {
break;
}
// If listeners were removed during emission, make sure the
// event handler we're going to fire wasn't removed.
if (originalListeners === this._eventEmitterListeners.get(aEvent) ||
this._eventEmitterListeners.get(aEvent).some(function(l) l === listener)) {
listener.apply(null, arguments);
}
}
},
}