Initial JS stub implementation of Object.observe. Adds support for...

Initial JS stub implementation of Object.observe. Adds support for .object/.unobserve/.notify/.deliverChangeRecords. No delivery mechanism is implemented for end-of-microtask.

Review URL: https://codereview.chromium.org/11225058
Patch from Rafael Weinstein <rafaelw@google.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12820 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

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
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"use strict";
+
+var InternalObjectIsFrozen = $Object.isFrozen;
+var InternalObjectFreeze = $Object.freeze;
+
+var InternalWeakMapProto = {
+  __proto__: null,
+  set: $WeakMap.prototype.set,
+  get: $WeakMap.prototype.get,
+  has: $WeakMap.prototype.has
+}
+
+function createInternalWeakMap() {
+  var map = new $WeakMap;
+  map.__proto__ = InternalWeakMapProto;
+  return map;
+}
+
+var observerInfoMap = createInternalWeakMap();
+var objectInfoMap = createInternalWeakMap();
+
+function ObjectObserve(object, callback) {
+  if (!IS_SPEC_OBJECT(object))
+    throw MakeTypeError("observe_non_object", ["observe"]);
+  if (!IS_SPEC_FUNCTION(callback))
+    throw MakeTypeError("observe_non_function", ["observe"]);
+  if (InternalObjectIsFrozen(callback))
+    throw MakeTypeError("observe_callback_frozen");
+
+  if (!observerInfoMap.has(callback)) {
+    // TODO: setup observerInfo.priority.
+    observerInfoMap.set(callback, {
+      pendingChangeRecords: null
+    });
+  }
+
+  var objectInfo = objectInfoMap.get(object);
+  if (IS_UNDEFINED(objectInfo)) {
+    // TODO: setup objectInfo.notifier
+    objectInfo = {
+      changeObservers: new InternalArray(callback)
+    };
+    objectInfoMap.set(object, objectInfo);
+    return;
+  }
+
+  var changeObservers = objectInfo.changeObservers;
+  if (changeObservers.indexOf(callback) >= 0)
+    return;
+
+  changeObservers.push(callback);
+}
+
+function ObjectUnobserve(object, callback) {
+  if (!IS_SPEC_OBJECT(object))
+    throw MakeTypeError("observe_non_object", ["unobserve"]);
+
+  var objectInfo = objectInfoMap.get(object);
+  if (IS_UNDEFINED(objectInfo))
+    return;
+
+  var changeObservers = objectInfo.changeObservers;
+  var index = changeObservers.indexOf(callback);
+  if (index < 0)
+    return;
+
+  changeObservers.splice(index, 1);
+}
+
+function EnqueueChangeRecord(changeRecord, observers) {
+  for (var i = 0; i < observers.length; i++) {
+    var observer = observers[i];
+    var observerInfo = observerInfoMap.get(observer);
+
+    // TODO: "activate" the observer
+
+    if (IS_NULL(observerInfo.pendingChangeRecords)) {
+      observerInfo.pendingChangeRecords = new InternalArray(changeRecord);
+    } else {
+      observerInfo.pendingChangeRecords.push(changeRecord);
+    }
+  }
+}
+
+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
+  };
+  for (var prop in changeRecord) {
+    if (prop === 'object')
+      continue;
+    newRecord[prop] = changeRecord[prop];
+  }
+  InternalObjectFreeze(newRecord);
+
+  EnqueueChangeRecord(newRecord, objectInfo.changeObservers);
+}
+
+function ObjectDeliverChangeRecords(callback) {
+  if (!IS_SPEC_FUNCTION(callback))
+    throw MakeTypeError("observe_non_function", ["deliverChangeRecords"]);
+
+  var observerInfo = observerInfoMap.get(callback);
+  if (IS_UNDEFINED(observerInfo))
+    return;
+
+  var pendingChangeRecords = observerInfo.pendingChangeRecords;
+  if (IS_NULL(pendingChangeRecords))
+    return;
+
+  observerInfo.pendingChangeRecords = null;
+  var delivered = [];
+  %MoveArrayContents(pendingChangeRecords, delivered);
+  try {
+    %Call(void 0, delivered, callback);
+  } catch (ex) {}
+}
+
+function SetupObjectObserve() {
+  %CheckIsBootstrapping();
+  InstallFunctions($Object, DONT_ENUM, $Array(
+    "deliverChangeRecords", ObjectDeliverChangeRecords,
+    "notify", ObjectNotify,  // TODO: Remove when getNotifier is implemented.
+    "observe", ObjectObserve,
+    "unobserve", ObjectUnobserve
+  ));
+}
+
+SetupObjectObserve();
\ No newline at end of file

test/mjsunit/harmony/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
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Flags: --harmony-object-observe
+
+var allObservers = [];
+function reset() {
+  allObservers.forEach(function(observer) { observer.reset(); });
+}
+
+function createObserver() {
+  "use strict";  // So that |this| in callback can be undefined.
+
+  var observer = {
+    records: undefined,
+    callbackCount: 0,
+    reset: function() {
+      this.records = undefined;
+      this.callbackCount = 0;
+    },
+    assertNotCalled: function() {
+      assertEquals(undefined, this.records);
+      assertEquals(0, this.callbackCount);
+    },
+    assertCalled: function() {
+      assertEquals(1, this.callbackCount);
+    },
+    assertRecordCount: function(count) {
+      this.assertCalled();
+      assertEquals(count, this.records.length);
+    },
+    assertCallbackRecords: function(recs) {
+      this.assertRecordCount(recs.length);
+      for (var i = 0; i < recs.length; i++) {
+        assertSame(this.records[i].object, recs[i].object);
+        assertEquals('string', typeof recs[i].type);
+        assertPropertiesEqual(this.records[i], recs[i]);
+      }
+    }
+  };
+
+  observer.callback = function(r) {
+    assertEquals(undefined, this);
+    assertEquals('object', typeof r);
+    assertTrue(r instanceof Array)
+    observer.records = r;
+    observer.callbackCount++;
+  };
+
+  observer.reset();
+  allObservers.push(observer);
+  return observer;
+}
+
+var observer = createObserver();
+assertEquals("function", typeof observer.callback);
+var obj = {};
+
+function frozenFunction() {}
+Object.freeze(frozenFunction);
+var nonFunction = {};
+var changeRecordWithAccessor = { type: 'foo' };
+var recordCreated = false;
+Object.defineProperty(changeRecordWithAccessor, 'name', {
+  get: function() {
+    recordCreated = true;
+  },
+  enumerable: true
+})
+
+// Object.observe
+assertThrows(function() { Object.observe("non-object", observer.callback); }, TypeError);
+assertThrows(function() { Object.observe(obj, nonFunction); }, TypeError);
+assertThrows(function() { Object.observe(obj, frozenFunction); }, TypeError);
+
+// Object.unobserve
+assertThrows(function() { Object.unobserve(4, observer.callback); }, TypeError);
+
+// Object.notify
+assertThrows(function() { Object.notify(obj, {}); }, TypeError);
+assertThrows(function() { Object.notify(obj, { type: 4 }); }, TypeError);
+Object.notify(obj, changeRecordWithAccessor);
+assertFalse(recordCreated);
+
+// Object.deliverChangeRecords
+assertThrows(function() { Object.deliverChangeRecords(nonFunction); }, TypeError);
+
+// Multiple records are delivered.
+Object.observe(obj, observer.callback);
+Object.notify(obj, {
+  object: obj,
+  type: 'updated',
+  name: 'foo',
+  expando: 1
+});
+
+Object.notify(obj, {
+  object: obj,
+  type: 'deleted',
+  name: 'bar',
+  expando2: 'str'
+});
+Object.deliverChangeRecords(observer.callback);
+observer.assertCallbackRecords([
+  { object: obj, name: 'foo', type: 'updated', expando: 1 },
+  { object: obj, name: 'bar', type: 'deleted', expando2: 'str' }
+]);
+
+// No delivery takes place if no records are pending
+reset();
+Object.deliverChangeRecords(observer.callback);
+observer.assertNotCalled();
+
+// Multiple observation has no effect.
+reset();
+Object.observe(obj, observer.callback);
+Object.observe(obj, observer.callback);
+Object.notify(obj, {
+  type: 'foo',
+});
+Object.deliverChangeRecords(observer.callback);
+observer.assertCalled();
+
+// Observation can be stopped.
+reset();
+Object.unobserve(obj, observer.callback);
+Object.notify(obj, {
+  type: 'foo',
+});
+Object.deliverChangeRecords(observer.callback);
+observer.assertNotCalled();
+
+// Multiple unobservation has no effect
+reset();
+Object.unobserve(obj, observer.callback);
+Object.unobserve(obj, observer.callback);
+Object.notify(obj, {
+  type: 'foo',
+});
+Object.deliverChangeRecords(observer.callback);
+observer.assertNotCalled();
+
+// Re-observation works and only includes changeRecords after of call.
+reset();
+Object.notify(obj, {
+  type: 'foo',
+});
+Object.observe(obj, observer.callback);
+Object.notify(obj, {
+  type: 'foo',
+});
+records = undefined;
+Object.deliverChangeRecords(observer.callback);
+observer.assertRecordCount(1);
+
+// Observing a continuous stream of changes, while itermittantly unobserving.
+reset();
+Object.observe(obj, observer.callback);
+Object.notify(obj, {
+  type: 'foo',
+  val: 1
+});
+
+Object.unobserve(obj, observer.callback);
+Object.notify(obj, {
+  type: 'foo',
+  val: 2
+});
+
+Object.observe(obj, observer.callback);
+Object.notify(obj, {
+  type: 'foo',
+  val: 3
+});
+
+Object.unobserve(obj, observer.callback);
+Object.notify(obj, {
+  type: 'foo',
+  val: 4
+});
+
+Object.observe(obj, observer.callback);
+Object.notify(obj, {
+  type: 'foo',
+  val: 5
+});
+
+Object.unobserve(obj, observer.callback);
+Object.deliverChangeRecords(observer.callback);
+observer.assertCallbackRecords([
+  { object: obj, type: 'foo', val: 1 },
+  { object: obj, type: 'foo', val: 3 },
+  { object: obj, type: 'foo', val: 5 }
+]);
+
+// Observing multiple objects; records appear in order;.
+reset();
+var obj2 = {};
+var obj3 = {}
+Object.observe(obj, observer.callback);
+Object.observe(obj3, observer.callback);
+Object.observe(obj2, observer.callback);
+Object.notify(obj, {
+  type: 'foo',
+});
+Object.notify(obj2, {
+  type: 'foo',
+});
+Object.notify(obj3, {
+  type: 'foo',
+});
+Object.deliverChangeRecords(observer.callback);
+observer.assertCallbackRecords([
+  { object: obj, type: 'foo' },
+  { object: obj2, type: 'foo' },
+  { object: obj3, type: 'foo' }
+]);
\ No newline at end of file