Merge pull request #565 from streamich/peritext-slices

Peritext `Point` class implementation

Author: streamich

src/json-crdt-extensions/peritext/Peritext.ts

@@ -0,0 +1,41 @@
+import {Anchor} from './constants';
+import {Point} from './point/Point';
+import {printTree} from '../../util/print/printTree';
+import {ArrNode, StrNode} from '../../json-crdt/nodes';
+import {type ITimestampStruct} from '../../json-crdt-patch/clock';
+import type {Model} from '../../json-crdt/model';
+import type {Printable} from '../../util/print/types';
+
+export class Peritext implements Printable {
+  constructor(
+    public readonly model: Model,
+    public readonly str: StrNode,
+    slices: ArrNode,
+  ) {}
+
+  public point(id: ITimestampStruct, anchor: Anchor = Anchor.After): Point {
+    return new Point(this, id, anchor);
+  }
+
+  public pointAt(pos: number, anchor: Anchor = Anchor.Before): Point {
+    const str = this.str;
+    const id = str.find(pos);
+    if (!id) return this.point(str.id, Anchor.After);
+    return this.point(id, anchor);
+  }
+
+  public pointAtStart(): Point {
+    return this.point(this.str.id, Anchor.After);
+  }
+
+  public pointAtEnd(): Point {
+    return this.point(this.str.id, Anchor.Before);
+  }
+
+  // ---------------------------------------------------------------- Printable
+
+  public toString(tab: string = ''): string {
+    const nl = () => '';
+    return this.constructor.name + printTree(tab, [(tab) => this.str.toString(tab)]);
+  }
+}

src/json-crdt-extensions/peritext/constants.ts

@@ -0,0 +1,43 @@
+export const enum Anchor {
+  Before = 0,
+  After = 1,
+}
+
+export const enum SliceHeaderMask {
+  X1Anchor = 0b1,
+  X2Anchor = 0b10,
+  Behavior = 0b11100,
+}
+
+export const enum SliceHeaderShift {
+  X1Anchor = 0,
+  X2Anchor = 1,
+  Behavior = 2,
+}
+
+export const enum SliceBehavior {
+  /**
+   * A Split slice, which is used to mark a block split position in the document.
+   * For example, paragraph, heading, blockquote, etc.
+   */
+  Split = 0b000,
+
+  /**
+   * Appends attributes to a stack of attributes for a specific slice type. This
+   * is useful when the same slice type can have multiple attributes, like
+   * inline comments, highlights, etc.
+   */
+  Stack = 0b001,
+
+  /**
+   * Overwrites the stack of attributes for a specific slice type. Could be used
+   * for simple inline formatting, like bold, italic, etc.
+   */
+  Overwrite = 0b010,
+
+  /**
+   * Removes all attributes for a specific slice type. For example, could be
+   * used to re-verse inline formatting, like bold, italic, etc.
+   */
+  Erase = 0b011,
+}