[DevTools] Introduce typed events.

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

Index: third_party/WebKit/Source/devtools/front_end/common/Object.js
diff --git a/third_party/WebKit/Source/devtools/front_end/common/Object.js b/third_party/WebKit/Source/devtools/front_end/common/Object.js
index cf053942051630186538752c734f6ee4ea6fcb5d..6f5d793c827a6d14ee94043e1b8a9248b4074a63 100644
--- a/third_party/WebKit/Source/devtools/front_end/common/Object.js
+++ b/third_party/WebKit/Source/devtools/front_end/common/Object.js
@@ -90,6 +90,56 @@ Common.Object = class {
     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);
+  }
 };
 
 /**
@@ -110,12 +160,15 @@ Common.Event = class {
 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);
@@ -148,6 +201,29 @@ Common.EventTarget.prototype = {
    * @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) {},
 };
 
 /**
@@ -167,3 +243,22 @@ Common.EventTarget.EventDescriptor = class {
     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;
+  }
+};