feat(json-crdt-extensions): 🎸 support right character retrieval for deleted points

Author: streamich

src/json-crdt-extensions/peritext/point/Point.ts

@@ -180,7 +180,13 @@ export class Point implements Pick<Stateful, 'refresh'>, Printable {
       return chunk ? new ChunkSlice(chunk, 0, 1) : undefined;
     }
     let chunk = this.chunk();
-    if (!chunk || chunk.del) return;
+    if (!chunk) return;
+    if (chunk.del) {
+      const nextId = this.nextId();
+      if (!nextId) return;
+      const tmp = new Point(this.txt, nextId, Anchor.Before);
+      return tmp.rightChar();
+    }
     if (this.anchor === Anchor.Before) {
       const off = this.id.time - chunk.id.time;
       return new ChunkSlice(chunk, off, 1);

src/json-crdt-extensions/peritext/point/__tests__/Point.spec.ts

@@ -552,12 +552,16 @@ describe('.rightChar()', () => {
     expect(end.rightChar()).toBe(undefined);
   });
 
-  test('retrieves left char of a deleted point', () => {
-    const {peritext, chunkD1} = setupWithChunkedText();
+  test('retrieves right char of a deleted point', () => {
+    const {peritext, chunkD1, chunkD2} = setupWithChunkedText();
     const p1 = peritext.point(chunkD1.id, Anchor.Before);
-    expect(p1.leftChar()!.view()).toBe('3');
+    expect(p1.rightChar()!.view()).toBe('4');
     const p2 = peritext.point(chunkD1.id, Anchor.After);
-    expect(p2.leftChar()!.view()).toBe('3');
+    expect(p2.rightChar()!.view()).toBe('4');
+    const p3 = peritext.point(chunkD2.id, Anchor.Before);
+    expect(p3.rightChar()!.view()).toBe('7');
+    const p4 = peritext.point(chunkD2.id, Anchor.After);
+    expect(p4.rightChar()!.view()).toBe('7');
   });
 });
 
@@ -630,4 +634,16 @@ describe('.leftChar()', () => {
       expect(char.view()).toBe(res[i]);
     }
   });
+
+  test('retrieves left char of a deleted point', () => {
+    const {peritext, chunkD1, chunkD2} = setupWithChunkedText();
+    const p1 = peritext.point(chunkD1.id, Anchor.Before);
+    expect(p1.leftChar()!.view()).toBe('3');
+    const p2 = peritext.point(chunkD1.id, Anchor.After);
+    expect(p2.leftChar()!.view()).toBe('3');
+    const p3 = peritext.point(chunkD2.id, Anchor.Before);
+    expect(p3.leftChar()!.view()).toBe('6');
+    const p4 = peritext.point(chunkD2.id, Anchor.After);
+    expect(p4.leftChar()!.view()).toBe('6');
+  });
 });