feat(json-crdt-extensions): 🎸 implement OverlayPointMarker

Author: streamich

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

@@ -0,0 +1,41 @@
+import {OverlayPoint} from './OverlayPoint';
+import {SliceType} from '../types';
+import type {Anchor} from '../rga/constants';
+import type {AbstractRga} from '../../../json-crdt/nodes/rga';
+import type {ITimestampStruct} from '../../../json-crdt-patch/clock';
+import type {SplitSlice} from '../slice/SplitSlice';
+
+export class OverlayPointMarker extends OverlayPoint {
+  /**
+   * Hash value of the preceding text contents, up until the next marker.
+   */
+  public textHash: number = 0;
+
+  /** @todo splice can always be set, maybe? */
+  constructor(protected readonly rga: AbstractRga<string>, id: ITimestampStruct, anchor: Anchor, public readonly slice: SplitSlice | undefined) {
+    super(rga, id, anchor);
+  }
+
+  /** @todo Rename or access it directly. */
+  public markerHash(): number {
+    return this.slice ? this.slice.hash : 0;
+  }
+
+  public tag(): SliceType | 0 {
+    if (!this.slice) return 0;
+    return this.slice.type;
+  }
+
+  public data(): unknown {
+    if (!this.slice) return undefined;
+    return this.slice.data();
+  }
+
+  // ---------------------------------------------------------------- Printable
+
+  public toStringName(tab: string, lite?: boolean): string {
+    const hash = lite ? '' : `#${this.textHash.toString(36).slice(-4)}`;
+    const tag = lite ? '' : `, ${JSON.stringify((this.tag() as any)[1])}`;
+    return `${super.toStringName(tab, lite)}${lite ? '' : ' '}${hash}${tag}`;
+  }
+}