perf(json-crdt-extensions): ⚡️ speed up range text materialization

src/json-crdt-extensions/peritext/rga/Range.ts

@@ -214,8 +214,9 @@ export class Range<T = string> implements Pick<Stateful, 'refresh'>, Printable {
     const endId = end.anchor === Anchor.After ? end.id : end.prevId();
     if (!startId || !endId) return '';
     let result = '';
-    rga.range0(undefined, startId, endId, (chunk: Chunk<T>, from: number, length: number) => {
-      if (chunk.data) result += chunk.view().slice(from, from + length);
+    rga.range0(start.chunk(), startId, endId, (chunk: Chunk<T>, from: number, length: number) => {
+      const data = chunk.data as string;
+      if (data) result += data.slice(from, from + length);
     });
     return result;
   }

src/json-crdt-extensions/peritext/rga/__tests__/Range.text.spec.ts

@@ -0,0 +1,32 @@
+import {Kit, setupHelloWorldKit, setupHelloWorldWithFewEditsKit, setupNumbersKit, setupNumbersWithTombstonesKit} from '../../__tests__/setup';
+
+const run = (setup: () => Kit) => {
+  test('can produce text for all possible ranges', () => {
+    const {peritext} = setup();
+    const length = peritext.strApi().length();
+    const str = peritext.strApi().view();
+    for (let i = 0; i < length - 1; i++) {
+      for (let j = 1; j <= length - i - i; j++) {
+        const range = peritext.rangeAt(i, j);
+        expect(range.text()).toBe(str.slice(i, i + j));
+        // console.log(str.slice(i, i + j));
+      }
+    }
+  });
+};
+
+describe('no edits "hello world"', () => {
+  run(setupHelloWorldKit);
+});
+
+describe('some edits "hello world"', () => {
+  run(setupHelloWorldWithFewEditsKit);
+});
+
+describe('no edits "number"', () => {
+  run(setupNumbersKit);
+});
+
+describe('heavy edits "number"', () => {
+  run(setupNumbersWithTombstonesKit);
+});