[DevTools] Introduce typed events.

third_party/WebKit/Source/devtools/front_end/common/Object.js

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 72 matching lines @@
    */
   dispatchEventToListeners(eventType, eventData) {
     if (!this._listeners || !this._listeners.has(eventType))
       return;
 
     var event = new Common.Event(eventData);
     var listeners = this._listeners.get(eventType).slice(0);
     for (var i = 0; i < listeners.length; ++i)
       listeners[i].listener.call(listeners[i].thisObject, event);
   }
+
+  /**
+   * @template T
+   * @override
+   * @param {function(new:T, ...)} eventType
+   * @param {function(!T)} listener
+   * @param {!Object=} thisObject
+   * @return {!Common.EventTarget.TypedEventDescriptor}
+   */
+  on(eventType, listener, thisObject) {
+    if (!this._listeners)
+      this._listeners = new Map();
+    if (!this._listeners.has(eventType))
+      this._listeners.set(eventType, []);
+    this._listeners.get(eventType).push({thisObject: thisObject, listener: listener});
+    return new Common.EventTarget.TypedEventDescriptor(this, eventType, thisObject, listener);
+  }
+
+  /**
+   * @template T
+   * @override
+   * @param {function(new:T, ...)} eventType
+   * @param {function(!T)} listener
+   * @param {!Object=} thisObject
+   */
+  off(eventType, listener, thisObject) {
+    if (!this._listeners || !this._listeners.has(eventType))
+      return;
+    var listeners = this._listeners.get(eventType);
+    for (var i = 0; i < listeners.length; ++i) {
+      if (listeners[i].listener === listener && listeners[i].thisObject === thisObject)
+        listeners.splice(i--, 1);
+    }
+    if (!listeners.length)
+      this._listeners.delete(eventType);
+  }
+
+  /**
+   * @template T
+   * @override
+   * @param {!T} event
+   */
+  emit(event) {
+    var eventType = event.constructor;
+    if (!this._listeners || !this._listeners.has(eventType))
+      return;
+    var listeners = this._listeners.get(eventType).slice(0);
+    for (var i = 0; i < listeners.length; ++i)
+      listeners[i].listener.call(listeners[i].thisObject, event);
+  }
 };
 
 /**
  * @unrestricted
  */
 Common.Event = class {
   /**
    * @param {*=} data
    */
   constructor(data) {
     this.data = data;
   }
 };
 
 /**
  * @interface
  */
 Common.EventTarget = function() {};
 
 /**
- * @param {!Array<!Common.EventTarget.EventDescriptor>} eventList
+ * @param {!Array<!Common.EventTarget.EventDescriptor|!Common.EventTarget.TypedEventDescriptor>} eventList
  */
 Common.EventTarget.removeEventListeners = function(eventList) {
   for (var i = 0; i < eventList.length; ++i) {
     var eventInfo = eventList[i];
-    eventInfo.eventTarget.removeEventListener(eventInfo.eventType, eventInfo.method, eventInfo.receiver);
+    if (eventInfo instanceof Common.EventTarget.EventDescriptor)
+      eventInfo.eventTarget.removeEventListener(eventInfo.eventType, eventInfo.method, eventInfo.receiver);
+    else
+      eventInfo.eventTarget.off(eventInfo.eventType, eventInfo.method, eventInfo.receiver);
   }
   // Do not hold references on unused event descriptors.
   eventList.splice(0, eventList.length);
 };
 
 Common.EventTarget.prototype = {
   /**
    * @param {symbol} eventType
    * @param {function(!Common.Event)} listener
    * @param {!Object=} thisObject
@@ skipping 12 matching lines @@
    * @param {symbol} eventType
    * @return {boolean}
    */
   hasEventListeners(eventType) {},
 
   /**
    * @param {symbol} eventType
    * @param {*=} eventData
    */
   dispatchEventToListeners(eventType, eventData) {},
+
+  /**
+   * @template T
+   * @param {function(new:T, ...)} eventType
+   * @param {function(!T)} listener
+   * @param {!Object=} thisObject
+   * @return {!Common.EventTarget.TypedEventDescriptor}
+   */
+  on(eventType, listener, thisObject) {},
+
+  /**
+   * @template T
+   * @param {function(new:T, ...)} eventType
+   * @param {function(!T)} listener
+   * @param {!Object=} thisObject
+   */
+  off(eventType, listener, thisObject) {},
+
+  /**
+   * @template T
+   * @param {!T} event
+   */
+  emit(event) {},
 };
 
 /**
  * @unrestricted
  */
 Common.EventTarget.EventDescriptor = class {
   /**
    * @param {!Common.EventTarget} eventTarget
    * @param {symbol} eventType
    * @param {(!Object|undefined)} receiver
    * @param {function(?):?} method
    */
   constructor(eventTarget, eventType, receiver, method) {
     this.eventTarget = eventTarget;
     this.eventType = eventType;
     this.receiver = receiver;
     this.method = method;
   }
 };
+
+/**
+ * @template T
+ * @unrestricted
+ */
+Common.EventTarget.TypedEventDescriptor = class {
+  /**
+   * @param {!Common.EventTarget} eventTarget
+   * @param {function(new:T, ...)} eventType
+   * @param {(!Object|undefined)} receiver
+   * @param {function(!T)} method
+   */
+  constructor(eventTarget, eventType, receiver, method) {
+    this.eventTarget = eventTarget;
+    this.eventType = eventType;
+    this.receiver = receiver;
+    this.method = method;
+  }
+};