feat(json-crdt-extensions): 🎸 improve Overlay.pairs() iterator

Author: streamich

src/json-crdt-extensions/peritext/__tests__/setup.ts

@@ -1,41 +1,18 @@
 import {s} from '../../../json-crdt-patch';
+import {Model} from '../../../json-crdt/model';
+import {SchemaToJsonNode} from '../../../json-crdt/schema/types';
 import {ModelWithExt, ext} from '../../ModelWithExt';
 
-/**
- * Creates a Peritext instance with text "0123456789", with single-char and
- * block-wise chunks, as well as with plenty of tombstones.
- */
-export const setupNumbersWithTombstones = () => {
-  const schema = s.obj({
-    text: ext.peritext.new('1234'),
-  });
-  const model = ModelWithExt.create(schema);
-  const str = model.s.text.toExt().text();
-  str.ins(1, '234');
-  str.ins(2, '345');
-  str.ins(3, '456');
-  str.ins(4, '567');
-  str.ins(5, '678');
-  str.ins(6, '789');
-  str.del(7, 1);
-  str.del(8, 1);
-  str.ins(0, '0');
-  str.del(1, 4);
-  str.del(2, 1);
-  str.ins(1, '1');
-  str.del(0, 1);
-  str.ins(0, '0');
-  str.ins(2, '234');
-  str.del(4, 7);
-  str.del(4, 2);
-  str.del(7, 3);
-  str.ins(6, '6789');
-  str.del(7, 2);
-  str.ins(7, '78');
-  str.del(10, 2);
-  str.del(2, 3);
-  str.ins(2, '234');
-  if (str.view() !== '0123456789') throw new Error('Invalid text');
+export type Schema = ReturnType<typeof schema>;
+export type Kit = ReturnType<typeof setupKit>;
+
+const schema = (text: string) => s.obj({
+  text: ext.peritext.new(text),
+});
+
+export const setupKit = (initialText: string = '', edits: (model: Model<SchemaToJsonNode<Schema>>) => void = () => {}) => {
+  const model = ModelWithExt.create(schema(initialText));
+  edits(model);
   const api = model.api;
   const peritextApi = model.s.text.toExt();
   const peritext = peritextApi.txt;
@@ -49,3 +26,70 @@ export const setupNumbersWithTombstones = () => {
     editor,
   };
 };
+
+export const setupHelloWorldKit = (): Kit => {
+  return setupKit('', (model) => {
+    const str = model.s.text.toExt().text();
+    str.ins(0, 'hello world');
+    if (str.view() !== 'hello world') throw new Error('Invalid text');
+  });
+};
+
+export const setupHelloWorldWithFewEditsKit = (): Kit => {
+  return setupKit('', (model) => {
+    const str = model.s.text.toExt().text();
+    str.ins(0, 'wworld');
+    str.ins(0, 'helo ');
+    str.ins(2, 'l');
+    str.del(7, 1);
+    if (str.view() !== 'hello world') throw new Error('Invalid text');
+  });
+};
+
+/**
+ * Creates a Peritext instance with text "0123456789", no edits.
+ */
+export const setupNumbersKit = (): Kit => {
+  return setupKit('', (model) => {
+    const str = model.s.text.toExt().text();
+    str.ins(0, '0123456789');
+    if (str.view() !== '0123456789') throw new Error('Invalid text');
+  });
+};
+
+/**
+ * Creates a Peritext instance with text "0123456789", with single-char and
+ * block-wise chunks, as well as with plenty of tombstones.
+ */
+export const setupNumbersWithTombstonesKit = (): Kit => {
+  return setupKit('1234', (model) => {
+    const str = model.s.text.toExt().text();
+    str.ins(0, '234');
+    str.ins(1, '234');
+    str.ins(2, '345');
+    str.ins(3, '456');
+    str.ins(4, '567');
+    str.ins(5, '678');
+    str.ins(6, '789');
+    str.del(7, 1);
+    str.del(8, 1);
+    str.ins(0, '0');
+    str.del(1, 4);
+    str.del(2, 1);
+    str.ins(1, '1');
+    str.del(0, 1);
+    str.ins(0, '0');
+    str.ins(2, '234');
+    str.del(4, 7);
+    str.del(4, 2);
+    str.del(7, 3);
+    str.ins(6, '6789');
+    str.del(7, 2);
+    str.ins(7, '78');
+    str.del(10, 2);
+    str.del(2, 3);
+    str.ins(2, '234');
+    str.del(10, 3);
+    if (str.view() !== '0123456789') throw new Error('Invalid text');
+  });
+};

src/json-crdt-extensions/peritext/editor/Editor.ts

@@ -10,9 +10,13 @@ import type {MarkerSlice} from '../slice/MarkerSlice';
 
 export class Editor<T = string> {
   public readonly saved: EditorSlices<T>;
+  public readonly extra: EditorSlices<T>;
+  public readonly local: EditorSlices<T>;
 
   constructor(public readonly txt: Peritext<T>) {
     this.saved = new EditorSlices(txt, txt.savedSlices);
+    this.extra = new EditorSlices(txt, txt.extraSlices);
+    this.local = new EditorSlices(txt, txt.localSlices);
   }
 
   public firstCursor(): Cursor<T> | undefined {

src/json-crdt-extensions/peritext/overlay/Overlay.ts

@@ -196,12 +196,35 @@ export class Overlay<T = string> implements Printable, Stateful {
   }
 
   public pairs0(after: undefined | OverlayPoint<T>): UndefIterator<OverlayPair<T>> {
+    const isEmpty = !this.root;
+    if (isEmpty) {
+      let closed = false;
+      return () => {
+        if (closed) return;
+        closed = true;
+        return [undefined, undefined];
+      }
+    }
     let p1: OverlayPoint<T> | undefined;
     let p2: OverlayPoint<T> | undefined;
     const iterator = this.points0(after);
     return () => {
+      const next = iterator();
+      const isEnd = !next;
+      if (isEnd) {
+        if (!p2 || p2.isAbsEnd()) return;
+        p1 = p2;
+        p2 = undefined;
+        return [p1, p2];
+      }
       p1 = p2;
-      p2 = iterator();
+      p2 = next;
+      if (!p1) {
+        if (p2 && p2.isAbsStart()) {
+          p1 = p2;
+          p2 = iterator();
+        }
+      }
       return (p1 || p2) ? [p1, p2] : undefined;
     };
   }