Merge pull request #466 from streamich/events-2.0

JSON CRDT Events 2.0

Author: streamich

src/json-crdt/__demos__/events.ts

@@ -25,7 +25,7 @@ const model = Model.withLogicalClock(1234); // 1234 is the session ID
 
 // DOM Level 2 node events
 const root = model.api.r;
-root.events.on('view', () => {
+root.events.onViewChanges.listen(() => {
   console.log('Root value changed');
 });
 

src/json-crdt/model/Model.ts

@@ -17,15 +17,6 @@ import type {NodeApi} from './api/nodes';
 
 export const UNDEFINED = new ConNode(ORIGIN, undefined);
 
-export const enum ModelChangeType {
-  /** When operations are applied through `.applyPatch()` directly. */
-  REMOTE = 0,
-  /** When local operations are applied through the `ModelApi`. */
-  LOCAL = 1,
-  /** When model is reset using the `.reset()` method. */
-  RESET = 2,
-}
-
 /**
  * In instance of Model class represents the underlying data structure,
  * i.e. model, of the JSON CRDT document.
@@ -140,15 +131,6 @@ export class Model<N extends JsonNode = JsonNode> implements Printable {
    */
   public tick: number = 0;
 
-  /**
-   * Callback called after every `applyPatch` call.
-   *
-   * When using the `.api` API, this property is set automatically by
-   * the {@link ModelApi} class. In that case use the `mode.api.evens.on('change')`
-   * to subscribe to changes.
-   */
-  public onchange: undefined | ((type: ModelChangeType) => void) = undefined;
-
   /**
    * Applies a batch of patches to the document.
    *
@@ -159,16 +141,27 @@ export class Model<N extends JsonNode = JsonNode> implements Printable {
     for (let i = 0; i < length; i++) this.applyPatch(patches[i]);
   }
 
+  /**
+   * Callback called before every `applyPatch` call.
+   */
+  public onbeforepatch?: (patch: Patch) => void = undefined;
+
+  /**
+   * Callback called after every `applyPatch` call.
+   */
+  public onpatch?: (patch: Patch) => void = undefined;
+
   /**
    * Applies a single patch to the document. All mutations to the model must go
    * through this method.
    */
   public applyPatch(patch: Patch) {
+    this.onbeforepatch?.(patch);
     const ops = patch.ops;
     const {length} = ops;
     for (let i = 0; i < length; i++) this.applyOperation(ops[i]);
     this.tick++;
-    this.onchange?.(ModelChangeType.REMOTE);
+    this.onpatch?.(patch);
   }
 
   /**
@@ -180,6 +173,7 @@ export class Model<N extends JsonNode = JsonNode> implements Printable {
    *
    * @param op Any JSON CRDT Patch operation
    * @ignore
+   * @internal
    */
   public applyOperation(op: JsonCrdtPatchOperation): void {
     this.clock.observe(op.id, op.span());
@@ -293,7 +287,7 @@ export class Model<N extends JsonNode = JsonNode> implements Printable {
     const node = this.index.get(value);
     if (!node) return;
     const api = node.api;
-    if (api) (api as NodeApi).events.onDelete();
+    if (api) (api as NodeApi).events.handleDelete();
     node.children((child) => this.deleteNodeTree(child.id));
     this.index.del(value);
   }
@@ -322,18 +316,40 @@ export class Model<N extends JsonNode = JsonNode> implements Printable {
     return this.fork(this.clock.sid);
   }
 
+  /**
+   * Callback called before model isi reset using the `.reset()` method.
+   */
+  public onbeforereset?: () => void = undefined;
+
+  /**
+   * Callback called after model has been reset using the `.reset()` method.
+   */
+  public onreset?: () => void = undefined;
+
   /**
    * Resets the model to equivalent state of another model.
    */
   public reset(to: Model<N>): void {
+    this.onbeforereset?.();
+    const index = this.index;
     this.index = new AvlMap<clock.ITimestampStruct, JsonNode>(clock.compare);
     const blob = to.toBinary();
     decoder.decode(blob, <any>this);
     this.clock = to.clock.clone();
     this.ext = to.ext.clone();
-    const api = this._api;
-    if (api) api.flush();
-    this.onchange?.(ModelChangeType.RESET);
+    this._api?.flush();
+    index.forEach(({v: node}) => {
+      const api = node.api as NodeApi | undefined;
+      if (!api) return;
+      const newNode = this.index.get(node.id);
+      if (!newNode) {
+        api.events.handleDelete();
+        return;
+      }
+      api.node = newNode;
+      newNode.api = api;
+    });
+    this.onreset?.();
   }
 
   /**

src/json-crdt/model/__tests__/Model.cloning.spec.ts

@@ -1,4 +1,5 @@
 import {until} from '../../../__tests__/util';
+import {schema} from '../../../json-crdt-patch';
 import {PatchBuilder} from '../../../json-crdt-patch/PatchBuilder';
 import {Model} from '../Model';
 
@@ -214,9 +215,24 @@ describe('reset()', () => {
     });
     doc2.api.str(['text']).ins(5, ' world');
     let cnt = 0;
-    doc2.api.events.on('change', () => cnt++);
+    doc2.api.onChanges.listen(() => cnt++);
     doc2.reset(doc1);
     await until(() => cnt > 0);
     expect(cnt).toBe(1);
   });
+
+  test('preserves API nodes when model is reset', async () => {
+    const doc1 = Model.withLogicalClock().setSchema(
+      schema.obj({
+        text: schema.str('hell'),
+      }),
+    );
+    const doc2 = doc1.fork();
+    doc2.s.text.toApi().ins(4, 'o');
+    const str = doc1.s.text.toApi();
+    expect(str === doc2.s.text.toApi()).toBe(false);
+    expect(str.view()).toBe('hell');
+    doc1.reset(doc2);
+    expect(str.view()).toBe('hello');
+  });
 });

src/json-crdt/model/__tests__/Model.events.spec.ts

@@ -1,11 +1,11 @@
 import {PatchBuilder} from '../../../json-crdt-patch';
-import {Model, ModelChangeType} from '../Model';
+import {Model} from '../Model';
 
 describe('DOM Level 0, .onchange event system', () => {
   it('should trigger the onchange event when a value is set', () => {
     const model = Model.withLogicalClock();
     let cnt = 0;
-    model.onchange = () => {
+    model.onpatch = () => {
       cnt++;
     };
     expect(cnt).toBe(0);
@@ -26,7 +26,7 @@ describe('DOM Level 0, .onchange event system', () => {
   it('should trigger the onchange event when a value is set to the same value', () => {
     const model = Model.withLogicalClock();
     let cnt = 0;
-    model.onchange = () => {
+    model.onpatch = () => {
       cnt++;
     };
     expect(cnt).toBe(0);
@@ -42,7 +42,7 @@ describe('DOM Level 0, .onchange event system', () => {
   it('should trigger the onchange event when a value is deleted', () => {
     const model = Model.withLogicalClock();
     let cnt = 0;
-    model.onchange = () => {
+    model.onpatch = () => {
       cnt++;
     };
     expect(cnt).toBe(0);
@@ -60,7 +60,7 @@ describe('DOM Level 0, .onchange event system', () => {
   it('should trigger the onchange event when a non-existent value is deleted', () => {
     const model = Model.withLogicalClock();
     let cnt = 0;
-    model.onchange = () => {
+    model.onpatch = () => {
       cnt++;
     };
     expect(cnt).toBe(0);
@@ -78,7 +78,7 @@ describe('DOM Level 0, .onchange event system', () => {
   it('should trigger when root value is changed', () => {
     const model = Model.withLogicalClock();
     let cnt = 0;
-    model.onchange = () => {
+    model.onpatch = () => {
       cnt++;
     };
     expect(cnt).toBe(0);
@@ -96,29 +96,12 @@ describe('DOM Level 0, .onchange event system', () => {
   });
 
   describe('event types', () => {
-    it('should trigger the onchange event with a REMOTE event type', () => {
-      const model = Model.withLogicalClock();
-      let cnt = 0;
-      model.onchange = (type) => {
-        expect(type).toBe(ModelChangeType.REMOTE);
-        cnt++;
-      };
-      const builder = new PatchBuilder(model.clock.clone());
-      builder.root(builder.json({foo: 123}));
-      const patch = builder.flush();
-      expect(cnt).toBe(0);
-      model.applyPatch(patch);
-      expect(cnt).toBe(1);
-      expect(model.view()).toStrictEqual({foo: 123});
-    });
-
     it('should trigger the onchange event with a RESET event type', () => {
       const model1 = Model.withLogicalClock();
       const model2 = Model.withLogicalClock();
       model2.api.root([1, 2, 3]);
       let cnt = 0;
-      model1.onchange = (type) => {
-        expect(type).toBe(ModelChangeType.RESET);
+      model1.onreset = () => {
         cnt++;
       };
       expect(cnt).toBe(0);