Merge pull request #705 from streamich/local-apply

Introduce `.applyLocalPatch()` method

Author: streamich

src/json-crdt/model/Model.ts

@@ -306,12 +306,33 @@ export class Model<N extends JsonNode = JsonNode<any>> implements Printable {
    */
   public onpatch?: (patch: Patch) => void = undefined;
 
+  /**
+   * Works like `applyPatch`, but is intended to be used by the local client
+   * for locally generated patches. It checks if the model clock is ahead of
+   * the patch clock and rebases the patch if necessary.
+   *
+   * @param patch A patch to apply to the document.
+   */
+  public applyLocalPatch(patch: Patch): void {
+    const id = patch.getId();
+    if (id) {
+      const clock = this.clock;
+      if (clock.sid === id.sid) {
+        const time = clock.time;
+        if (time > id.time) patch = patch.rebase(time);
+      }
+    }
+    this.applyPatch(patch);
+  }
+
   /**
    * Applies a single patch to the document. All mutations to the model must go
    * through this method. (With the only exception of local changes through API,
    * which have an alternative path.)
+   *
+   * @param patch A patch to apply to the document.
    */
-  public applyPatch(patch: Patch) {
+  public applyPatch(patch: Patch): void {
     this.onbeforepatch?.(patch);
     const ops = patch.ops;
     const {length} = ops;

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

@@ -0,0 +1,46 @@
+import {s} from '../../../json-crdt-patch';
+import {Model} from '../Model';
+
+describe('.applyLocalPatch()', () => {
+  test('advances clock of a locally created patch', () => {
+    const schema = s.obj({});
+    const doc1 = Model.create(schema);
+    const doc2 = doc1.clone();
+    const time1 = doc1.clock.time;
+    doc1.s.toApi().set({a: 1});
+    const time2 = doc1.clock.time;
+    doc2.s.toApi().set({b: 2});
+    const time3 = doc1.clock.time;
+    expect(time2 > time1).toBe(true);
+    expect(time2).toBe(time3);
+    const patch = doc2.api.flush()!;
+    const time4 = patch.getId()!.time;
+    expect(time4).toBe(time1);
+    expect(doc1.view()).toEqual({a: 1});
+    doc1.applyLocalPatch(patch);
+    const time5 = doc1.clock.time;
+    expect(time5 > time3).toBe(true);
+    expect(doc1.view()).toEqual({a: 1, b: 2});
+  });
+
+  test('does not advance clock of a patch of a fork', () => {
+    const schema = s.obj({});
+    const doc1 = Model.create(schema);
+    const doc2 = doc1.fork();
+    const time1 = doc1.clock.time;
+    doc1.s.toApi().set({a: 1});
+    const time2 = doc1.clock.time;
+    doc2.s.toApi().set({b: 2});
+    const time3 = doc1.clock.time;
+    expect(time2 > time1).toBe(true);
+    expect(time2).toBe(time3);
+    const patch = doc2.api.flush()!;
+    const time4 = patch.getId()!.time;
+    expect(time4).toBe(time1);
+    expect(doc1.view()).toEqual({a: 1});
+    doc1.applyLocalPatch(patch);
+    const time5 = doc1.clock.time;
+    expect(time5).toBe(time3);
+    expect(doc1.view()).toEqual({a: 1, b: 2});
+  });
+});

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

@@ -4,7 +4,7 @@ import {Model} from '../Model';
 describe('Document', () => {
   describe('JSON builder', () => {
     test('can create object using JSON builder', () => {
-      const doc = Model.withLogicalClock();
+      const doc = Model.create();
       const builder = new PatchBuilder(doc.clock);
       const obj = builder.json({});
       builder.root(obj);
@@ -13,7 +13,7 @@ describe('Document', () => {
     });
 
     test('can create complex object', () => {
-      const doc = Model.withLogicalClock();
+      const doc = Model.create();
       const builder = new PatchBuilder(doc.clock);
       const json = {
         score: 123,