feat(json-crdt-extensions): 🎸 improve mutations in persisted slices

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

@@ -1,5 +1,4 @@
 import {Point} from '../rga/Point';
-import {Range} from '../rga/Range';
 import {CursorAnchor} from '../slice/constants';
 import {PersistedSlice} from '../slice/PersistedSlice';
 
@@ -8,6 +7,8 @@ export class Cursor<T = string> extends PersistedSlice<T> {
     return this.type as CursorAnchor;
   }
 
+  // ---------------------------------------------------------------- mutations
+
   public set anchorSide(value: CursorAnchor) {
     this.update({type: value});
   }
@@ -20,31 +21,15 @@ export class Cursor<T = string> extends PersistedSlice<T> {
     return this.anchorSide === CursorAnchor.Start ? this.end : this.start;
   }
 
-  public set(start: Point<T>, end?: Point<T>, anchorSide: CursorAnchor = this.anchorSide): void {
-    if (!end || end === start) end = start.clone();
-    super.set(start, end);
+  public set(start: Point<T>, end: Point<T> = start, anchorSide: CursorAnchor = this.anchorSide): void {
+    this.start = start;
+    this.end = end === start ? end.clone() : end;
     this.update({
       range: this,
       type: anchorSide,
     });
   }
 
-  /** TODO: Move to {@link PersistedSlice}. */
-  public setAt(start: number, length: number = 0): void {
-    let at = start;
-    let len = length;
-    if (len < 0) {
-      at += len;
-      len = -len;
-    }
-    const range = Range.at<T>(this.rga, start, length);
-    const anchorSide = this.anchorSide;
-    this.update({
-      range,
-      type: anchorSide !== this.anchorSide ? anchorSide : undefined,
-    });
-  }
-
   /**
    * Move one of the edges of the cursor to a new point.
    *
@@ -64,9 +49,7 @@ export class Cursor<T = string> extends PersistedSlice<T> {
   public move(move: number): void {
     const {start, end} = this;
     start.move(move);
-    if (start !== end) {
-      end.move(move);
-    }
+    if (start !== end) end.move(move);
     this.set(start, end);
   }
 

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

@@ -119,26 +119,16 @@ export class Range<T = string> implements Pick<Stateful, 'refresh'>, Printable {
     return start2.cmp(end2) === 0;
   }
 
-  /**
-   * Collapse the range to the start point and sets the anchor position to be
-   * "after" the character.
-   */
-  public collapseToStart(): void {
-    this.start = this.start.clone();
-    this.start.refAfter();
-    this.end = this.start.clone();
+  public contains(range: Range<T>): boolean {
+    return this.start.cmpSpatial(range.start) <= 0 && this.end.cmpSpatial(range.end) >= 0;
   }
 
-  /**
-   * Collapse the range to the end point and sets the anchor position to be
-   * "before" the character.
-   */
-  public collapseToEnd(): void {
-    this.end = this.end.clone();
-    this.end.refAfter();
-    this.start = this.end.clone();
+  public containsPoint(point: Point<T>): boolean {
+    return this.start.cmpSpatial(point) <= 0 && this.end.cmpSpatial(point) >= 0;
   }
 
+  // ---------------------------------------------------------------- mutations
+
   public set(start: Point<T>, end: Point<T> = start): void {
     this.start = start;
     this.end = end === start ? end.clone() : end;
@@ -158,12 +148,26 @@ export class Range<T = string> implements Pick<Stateful, 'refresh'>, Printable {
     this.set(point);
   }
 
-  public contains(range: Range<T>): boolean {
-    return this.start.cmpSpatial(range.start) <= 0 && this.end.cmpSpatial(range.end) >= 0;
+  /**
+   * Collapse the range to the start point and sets the anchor position to be
+   * "after" the character.
+   */
+  public collapseToStart(): void {
+    const start = this.start.clone();
+    start.refAfter();
+    const end = start.clone();
+    this.set(start, end);
   }
 
-  public containsPoint(point: Point<T>): boolean {
-    return this.start.cmpSpatial(point) <= 0 && this.end.cmpSpatial(point) >= 0;
+  /**
+   * Collapse the range to the end point and sets the anchor position to be
+   * "before" the character.
+   */
+  public collapseToEnd(): void {
+    const end = this.end.clone();
+    end.refAfter();
+    const start = this.end.clone();
+    this.set(start, end);
   }
 
   /**

src/json-crdt-extensions/peritext/slice/PersistedSlice.ts

@@ -4,7 +4,7 @@ import {Range} from '../rga/Range';
 import {updateNode} from '../../../json-crdt/hash';
 import {printTree} from 'tree-dump/lib/printTree';
 import {Anchor} from '../rga/constants';
-import {SliceHeaderMask, SliceHeaderShift, SliceBehavior, SliceTupleIndex} from './constants';
+import {SliceHeaderMask, SliceHeaderShift, SliceBehavior, SliceTupleIndex, CursorAnchor} from './constants';
 import {CONST} from '../../../json-hash';
 import {Timestamp, compare} from '../../../json-crdt-patch/clock';
 import {VecNode} from '../../../json-crdt/nodes';
@@ -66,6 +66,22 @@ export class PersistedSlice<T = string> extends Range<T> implements MutableSlice
     return this.model.api.wrap(this.tuple);
   }
 
+  // ---------------------------------------------------------------- mutations
+
+  public set(start: Point<T>, end: Point<T> = start): void {
+    super.set(start, end);
+    this.update({range: this});
+  }
+
+  /**
+   * Expand range left and right to contain all invisible space: (1) tombstones,
+   * (2) anchors of non-deleted adjacent chunks.
+   */
+  public expand(): void {
+    super.expand();
+    this.update({range: this});
+  }
+
   // ------------------------------------------------------------- MutableSlice
 
   public readonly id: ITimestampStruct;