Object.observe: generate change records for named properties.

src/object-observe.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 50 matching lines @@
     });
   }
 
   var objectInfo = objectInfoMap.get(object);
   if (IS_UNDEFINED(objectInfo)) {
     // TODO: setup objectInfo.notifier
     objectInfo = {
       changeObservers: new InternalArray(callback)
     };
     objectInfoMap.set(object, objectInfo);
+    %SetIsObserved(object, true);
     return;
   }

[rafaelw, 2012/10/31 14:44:31]

do we have JS debug-only ASSERTS? If so, it'd be nice to ASSERT(%IsObserved)

[rossberg, 2012/11/05 17:11:08]

Unfortunately, no.

 
   var changeObservers = objectInfo.changeObservers;
   if (changeObservers.indexOf(callback) >= 0)
     return;
 
   changeObservers.push(callback);
 }
 
 function ObjectUnobserve(object, callback) {
   if (!IS_SPEC_OBJECT(object))
@@ skipping 19 matching lines @@
     // TODO: "activate" the observer
 
     if (IS_NULL(observerInfo.pendingChangeRecords)) {
       observerInfo.pendingChangeRecords = new InternalArray(changeRecord);
     } else {
       observerInfo.pendingChangeRecords.push(changeRecord);
     }
   }
 }
 
+function NotifyChange(type, object, name, oldValue) {
+  var objectInfo = objectInfoMap.get(object);
+  if (IS_UNDEFINED(objectInfo)) return;

[rafaelw, 2012/10/31 14:44:31]

Seems like we should CHECK() here - can we crash from JS? This should never
happen, right?

[rossberg, 2012/11/05 17:11:08]

There is no direct way to do that, but I just removed the line, so that the
access below would throw an exception. Then the !threw assertion in
JSObject::Notify would fire.

+
+  var changeRecord = { type: type, object: object, name: name };
+  if (arguments.length == 4) changeRecord.oldValue = oldValue;

[rafaelw, 2012/10/31 14:44:31]

For safety, I think that you should switch on arguments.length and create one of
two object literals. $Object is theoritically exposed and user script could have
installed an accessor on Object.prototype.oldValue.

[rossberg, 2012/11/05 17:11:08]

Done.

+  InternalObjectFreeze(changeRecord);
+  EnqueueChangeRecord(changeRecord, objectInfo.changeObservers);
+}
+
 function ObjectNotify(object, changeRecord) {
   // TODO: notifier needs to be [[THIS]]
   if (!IS_STRING(changeRecord.type))
     throw MakeTypeError("observe_type_non_string");
 
   var objectInfo = objectInfoMap.get(object);
   if (IS_UNDEFINED(objectInfo))
     return;
 
   var newRecord = {
-    object: object  // TODO: Needs to be 'object' retreived from notifier
+    object: object  // TODO: Needs to be 'object' retrieved from notifier
   };
   for (var prop in changeRecord) {
     if (prop === 'object')
       continue;
     newRecord[prop] = changeRecord[prop];
   }
   InternalObjectFreeze(newRecord);
 
   EnqueueChangeRecord(newRecord, objectInfo.changeObservers);
 }
@@ skipping 21 matching lines @@
 function SetupObjectObserve() {
   %CheckIsBootstrapping();
   InstallFunctions($Object, DONT_ENUM, $Array(
     "deliverChangeRecords", ObjectDeliverChangeRecords,
     "notify", ObjectNotify,  // TODO: Remove when getNotifier is implemented.
     "observe", ObjectObserve,
     "unobserve", ObjectUnobserve
   ));
 }
 
-SetupObjectObserve();
+SetupObjectObserve();