Autotrack, take 2

packages/@glimmer/component/src/component.ts

@@ -1,5 +1,6 @@
 import { assert } from "@glimmer/util";
 import { metaFor } from "./tracked";
+import { CURRENT_TAG } from "@glimmer/reference";
 
 export interface Bounds {
   firstNode: Node;
@@ -266,7 +267,7 @@ class Component {
 
   set args(args) {
     this.__args__ = args;
-    metaFor(this).dirtyableTagFor("args").inner.dirty();
+    metaFor(this).updatableTagFor("args").inner.update(CURRENT_TAG);
   }
 
   /** @private

packages/@glimmer/component/src/tracked.ts

@@ -1,6 +1,23 @@
 import { DEBUG } from "@glimmer/env";
-import { Tag, DirtyableTag, TagWrapper, combine, CONSTANT_TAG } from "@glimmer/reference";
-import { dict, Dict } from "@glimmer/util";
+import { Tag, DirtyableTag, UpdatableTag, TagWrapper, combine, CONSTANT_TAG, CURRENT_TAG } from "@glimmer/reference";
+import { dict, Dict, Option } from "@glimmer/util";
+
+/**
+ * An object that that tracks @tracked properties that were consumed.
+ */
+class Tracker {
+  private tags = new Set<Tag>();
+
+  add(tag: Tag) {
+    this.tags.add(tag);
+  }
+
+  combine(): Tag {
+    let tags: Tag[] = [];
+    this.tags.forEach(tag => tags.push(tag));
+    return combine(tags);
+  }
+}
 
 /**
  * @decorator
@@ -82,19 +99,62 @@ export function tracked(...dependencies: any[]): any {
   }
 }
 
+/**
+ * Whenever a tracked computed property is entered, the current tracker is
+ * saved off and a new tracker is replaced.
+ * 
+ * Any tracked properties consumed are added to the current tracker.
+ * 
+ * When a tracked computed property is exited, the tracker's tags are
+ * combined and added to the parent tracker.
+ * 
+ * The consequence is that each tracked computed property has a tag
+ * that corresponds to the tracked properties consumed inside of
+ * itself, including child tracked computed properties.
+ */
+let CURRENT_TRACKER: Option<Tracker> = null;
+
 function descriptorForTrackedComputedProperty(target: any, key: any, descriptor: PropertyDescriptor, dependencies: string[]): PropertyDescriptor {
   let meta = metaFor(target);
   meta.trackedProperties[key] = true;
   meta.trackedPropertyDependencies[key] = dependencies || [];
 
+  let get = descriptor.get as Function;
+  let set = descriptor.set as Function;
+
+  function getter(this: any) {
+    // Swap the parent tracker for a new tracker
+    let old = CURRENT_TRACKER;
+    let tracker = CURRENT_TRACKER = new Tracker();
+
+    // Call the getter
+    let ret = get.call(this);
+
+    // Swap back the parent tracker
+    CURRENT_TRACKER = old;
+
+    // Combine the tags in the new tracker and add them to the parent tracker
+    let tag = tracker.combine();
+    if (CURRENT_TRACKER) CURRENT_TRACKER.add(tag);
+
+    // Update the UpdatableTag for this property with the tag for all of the
+    // consumed dependencies.
+    metaFor(this).updatableTagFor(key).inner.update(tag);
+
+    return ret;
+  }
+
   return {
     enumerable: true,
     configurable: false,
-    get: descriptor.get,
+    get: getter,
     set: function() {
-      metaFor(this).dirtyableTagFor(key).inner.dirty();
-      descriptor.set.apply(this, arguments);
-      propertyDidChange();
+      // Bump the global revision counter
+      EPOCH.inner.dirty();
+
+      // Mark the UpdatableTag for this property with the current tag.
+      metaFor(this).updatableTagFor(key).inner.update(CURRENT_TAG);
+      set.apply(this, arguments);
     }
   };
 }
@@ -125,11 +185,16 @@ function installTrackedProperty(target: any, key: Key) {
     configurable: true,
 
     get() {
+      if (CURRENT_TRACKER) CURRENT_TRACKER.add(metaFor(this).updatableTagFor(key));
       return this[shadowKey];
     },
 
     set(newValue) {
-      metaFor(this).dirtyableTagFor(key).inner.dirty();
+      // Bump the global revision counter
+      EPOCH.inner.dirty();
+
+      // Mark the UpdatableTag for this property with the current tag.
+      metaFor(this).updatableTagFor(key).inner.update(CURRENT_TAG);
       this[shadowKey] = newValue;
       propertyDidChange();
     }
@@ -152,13 +217,13 @@ function installTrackedProperty(target: any, key: Key) {
  */
 export default class Meta {
   tags: Dict<Tag>;
-  computedPropertyTags: Dict<TagWrapper<DirtyableTag>>;
+  computedPropertyTags: Dict<TagWrapper<UpdatableTag>>;
   trackedProperties: Dict<boolean>;
   trackedPropertyDependencies: Dict<string[]>;
 
   constructor(parent: Meta) {
     this.tags = dict<Tag>();
-    this.computedPropertyTags = dict<TagWrapper<DirtyableTag>>();
+    this.computedPropertyTags = dict<TagWrapper<UpdatableTag>>();
     this.trackedProperties = parent ? Object.create(parent.trackedProperties) : dict<boolean>();
     this.trackedPropertyDependencies = parent ? Object.create(parent.trackedPropertyDependencies) : dict<string[]>();
   }
@@ -168,8 +233,8 @@ export default class Meta {
    * by e.g. Glimmer VM to detect when a property should be re-rendered. Think
    * of this as the "public-facing" tag.
    *
-   * For static tracked properties, this is a single DirtyableTag. For computed
-   * properties, it is a combinator of the property's DirtyableTag as well as
+   * For static tracked properties, this is a single UpdatableTag. For computed
+   * properties, it is a combinator of the property's UpdatableTag as well as
    * all of its dependencies' tags.
    */
   tagFor(key: Key): Tag {
@@ -186,31 +251,31 @@ export default class Meta {
 
   /**
    * The tag used internally to invalidate when a tracked property is set. For
-   * static properties, this is the same DirtyableTag returned from `tagFor`.
-   * For computed properties, it is the DirtyableTag used as one of the tags in
+   * static properties, this is the same UpdatableTag returned from `tagFor`.
+   * For computed properties, it is the UpdatableTag used as one of the tags in
    * the tag combinator of the CP and its dependencies.
   */
-  dirtyableTagFor(key: Key): TagWrapper<DirtyableTag> {
+  updatableTagFor(key: Key): TagWrapper<UpdatableTag> {
     let dependencies = this.trackedPropertyDependencies[key];
     let tag;
 
     if (dependencies) {
       // The key is for a computed property.
       tag = this.computedPropertyTags[key];
       if (tag) { return tag; }
-      return this.computedPropertyTags[key] = DirtyableTag.create();
+      return this.computedPropertyTags[key] = UpdatableTag.create(CURRENT_TAG);
     } else {
       // The key is for a static property.
       tag = this.tags[key];
-      if (tag) { return tag as TagWrapper<DirtyableTag>; }
-      return this.tags[key] = DirtyableTag.create();
+      if (tag) { return tag as TagWrapper<UpdatableTag>; }
+      return this.tags[key] = UpdatableTag.create(CURRENT_TAG);
     }
   }
 }
 
 function combinatorForComputedProperties(meta: Meta, key: Key, dependencies: Key[] | void): Tag {
   // Start off with the tag for the CP's own dirty state.
-  let tags: Tag[] = [meta.dirtyableTagFor(key)];
+  let tags: Tag[] = [meta.updatableTagFor(key)];
 
   // Next, add in all of the tags for its dependencies.
   if (dependencies && dependencies.length) {
@@ -243,6 +308,8 @@ function hasOwnProperty(obj: any, key: symbol) {
   return hOP.call(obj, key);
 }
 
+const EPOCH = DirtyableTag.create();
+
 let propertyDidChange = function() {};
 
 export function setPropertyDidChange(cb: () => void) {
@@ -300,7 +367,7 @@ export function tagForProperty(obj: any, key: string, throwError: UntrackedPrope
  */
 function installDevModeErrorInterceptor(obj: object, key: string, throwError: UntrackedPropertyErrorThrower) {
   let target = obj;
-  let descriptor: PropertyDescriptor;
+  let descriptor: Option<PropertyDescriptor> = null;
 
   // Find the descriptor for the current property. We may need to walk the
   // prototype chain to do so. If the property is undefined, we may never get a
@@ -316,16 +383,18 @@ function installDevModeErrorInterceptor(obj: object, key: string, throwError: Un
   // If possible, define a property descriptor that passes through the current
   // value on reads but throws an exception on writes.
   if (descriptor) {
+    let { get, value } = descriptor;
+
     if (descriptor.configurable || !hasOwnDescriptor) {
       Object.defineProperty(obj, key, {
         configurable: descriptor.configurable,
         enumerable: descriptor.enumerable,
 
         get() {
-          if (descriptor.get) {
-            return descriptor.get.call(this);
+          if (get) {
+            return get.call(this);
           } else {
-            return descriptor.value;
+            return value;
           }
         },
 

packages/@glimmer/component/test/browser/tracked-property-test.ts

@@ -172,15 +172,14 @@ test('can track a computed property', (assert) => {
 
 test('tracked computed properties are invalidated when their dependencies are invalidated', (assert) => {
   class TrackedPerson {
-    @tracked('fullName')
-    get salutation() {
+    @tracked get salutation() {
       return `Hello, ${this.fullName}!`;
     }
 
-    @tracked('firstName', 'lastName')
-    get fullName() {
+    @tracked get fullName() {
       return `${this.firstName} ${this.lastName}`;
     }
+
     set fullName(fullName) {
       let [firstName, lastName] = fullName.split(' ');
       this.firstName = firstName;
@@ -192,8 +191,8 @@ test('tracked computed properties are invalidated when their dependencies are in
   }
 
   let obj = new TrackedPerson();
-  assert.strictEqual(obj.salutation, 'Hello, Tom Dale!');
-  assert.strictEqual(obj.fullName, 'Tom Dale');
+  assert.strictEqual(obj.salutation, 'Hello, Tom Dale!', `the saluation field is valid`);
+  assert.strictEqual(obj.fullName, 'Tom Dale', `the fullName field is valid`);
 
   let tag = tagForProperty(obj, 'salutation');
   let snapshot = tag.value();
@@ -219,6 +218,83 @@ test('tracked computed properties are invalidated when their dependencies are in
   assert.strictEqual(tag.validate(snapshot), true);
 });
 
+test('nested @tracked in multiple objects', (assert) => {
+  class TrackedPerson {
+    @tracked get salutation() {
+      return `Hello, ${this.fullName}!`;
+    }
+
+    @tracked get fullName(): string {
+      return `${this.firstName} ${this.lastName}`;
+    }
+
+    set fullName(fullName: string) {
+      let [firstName, lastName] = fullName.split(' ');
+      this.firstName = firstName;
+      this.lastName = lastName;
+    }
+
+    toString() {
+      return this.fullName;
+    }
+
+    @tracked firstName = 'Tom';
+    @tracked lastName = 'Dale';
+  }
+
+  class TrackedContact {
+    @tracked email: string;
+    @tracked person: TrackedPerson;
+
+    constructor(person: TrackedPerson, email: string) {
+      this.person = person;
+      this.email = email;
+    }
+
+    @tracked get contact(): string {
+      return `${this.person} @ ${this.email}`;
+    }
+  }
+
+  let obj = new TrackedContact(new TrackedPerson(), 'tom@example.com');
+  assert.strictEqual(obj.contact, 'Tom Dale @ tom@example.com', `the contact field is valid`);
+  assert.strictEqual(obj.person.fullName, 'Tom Dale', `the fullName field is valid`);
+  let person = obj.person;
+
+  let tag = tagForProperty(obj, 'contact');
+  let snapshot = tag.value();
+  assert.ok(tag.validate(snapshot), 'tag should be valid to start');
+
+  person.firstName = 'Edsger';
+  person.lastName = 'Dijkstra';
+  assert.strictEqual(tag.validate(snapshot), false, 'tag is invalidated after nested dependency is set');
+  assert.strictEqual(person.fullName, 'Edsger Dijkstra');
+  assert.strictEqual(obj.contact, 'Edsger Dijkstra @ tom@example.com');
+
+  snapshot = tag.value();
+  assert.strictEqual(tag.validate(snapshot), true);
+
+  person.fullName = 'Alan Kay';
+  assert.strictEqual(tag.validate(snapshot), false, 'tag is invalidated after chained dependency is set');
+  assert.strictEqual(person.fullName, 'Alan Kay');
+  assert.strictEqual(person.firstName, 'Alan');
+  assert.strictEqual(person.lastName, 'Kay');
+  assert.strictEqual(obj.contact, 'Alan Kay @ tom@example.com');
+
+  snapshot = tag.value();
+  assert.strictEqual(tag.validate(snapshot), true);
+
+  obj.email = "alan@example.com";
+  assert.strictEqual(tag.validate(snapshot), false, 'tag is invalidated after chained dependency is set');
+  assert.strictEqual(person.fullName, 'Alan Kay');
+  assert.strictEqual(person.firstName, 'Alan');
+  assert.strictEqual(person.lastName, 'Kay');
+  assert.strictEqual(obj.contact, 'Alan Kay @ alan@example.com');
+
+  snapshot = tag.value();
+  assert.strictEqual(tag.validate(snapshot), true);
+});
+
 module('[@glimmer/component] Tracked Property Warning in Development Mode');
 
 if (DEBUG) {