Merge pull request #599 from streamich/peritext-overlay

Peritext `OverlayPoint`

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

@@ -49,6 +49,7 @@ export class Peritext implements Printable {
    *
    * @param pos Position of the character in the text.
    * @param anchor Whether the point should attach before or after a character.
+   *               Defaults to "before".
    * @returns The point.
    */
   public pointAt(pos: number, anchor: Anchor = Anchor.Before): Point {

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

@@ -0,0 +1,235 @@
+import {Point} from '../rga/Point';
+import {compare} from '../../../json-crdt-patch/clock';
+import {OverlayRef, OverlayRefSliceEnd, OverlayRefSliceStart} from './refs';
+import {printTree} from 'sonic-forest/lib/print/printTree';
+import type {SplitSlice} from '../slice/SplitSlice';
+import type {HeadlessNode} from 'sonic-forest/lib/types';
+import type {Printable} from '../../../util/print/types';
+import type {Slice} from '../slice/types';
+
+/**
+ * A {@link Point} which is indexed in the {@link Overlay} tree. Represents
+ * sparse locations in the string of the places where annotation slices start,
+ * end, or are broken down by other intersecting slices.
+ */
+export class OverlayPoint extends Point implements Printable, HeadlessNode {
+  /**
+   * Hash of text contents until the next {@link OverlayPoint}. This field is
+   * modified by the {@link Overlay} tree.
+   */
+  public hash: number = 0;
+
+  // ------------------------------------------------------------------- layers
+
+  /**
+   * Sorted list of layers, contains the interval from this point to the next
+   * one. A *layer* is a part of a slice from the current point to the next one.
+   * This interval can contain many layers, as the slices can be overlap.
+   */
+  public readonly layers: Slice[] = [];
+
+  /**
+   * Inserts a slice to the list of layers which contains the area from this
+   * point until the next one. The operation is idempotent, so inserting the
+   * same slice twice will not change the state of the point. The layers are
+   * sorted by the slice ID.
+   *
+   * @param slice Slice to add to the layer list.
+   */
+  public addLayer(slice: Slice): void {
+    const layers = this.layers;
+    const length = layers.length;
+    if (!length) {
+      layers.push(slice);
+      return;
+    }
+    // We attempt to insert from the end of the list, as it is the most likely
+    // scenario. And `.push()` is more efficient than `.unshift()`.
+    const lastSlice = layers[length - 1];
+    const sliceId = slice.id;
+    const cmp = compare(lastSlice.id, sliceId);
+    if (cmp < 0) {
+      layers.push(slice);
+      return;
+    } else if (!cmp) return;
+    for (let i = length - 2; i >= 0; i--) {
+      const currSlice = layers[i];
+      const cmp = compare(currSlice.id, sliceId);
+      if (cmp < 0) {
+        layers.splice(i + 1, 0, slice);
+        return;
+      } else if (!cmp) return;
+    }
+    layers.unshift(slice);
+  }
+
+  /**
+   * Removes a slice from the list of layers, which start from this overlay
+   * point.
+   *
+   * @param slice Slice to remove from the layer list.
+   */
+  public removeLayer(slice: Slice): void {
+    const layers = this.layers;
+    const length = layers.length;
+    for (let i = 0; i < length; i++) {
+      if (layers[i] === slice) {
+        layers.splice(i, 1);
+        return;
+      }
+    }
+  }
+
+  // ------------------------------------------------------------------ markers
+
+  /**
+   * Collapsed slices - markers (block splits), which represent a single point
+   * in the text, even if the start and end of the slice are different.
+   * @deprecated This field might happen to be not necessary.
+   */
+  public readonly markers: Slice[] = [];
+
+  /**
+   * Inserts a slice to the list of markers which represent a single point in
+   * the text, even if the start and end of the slice are different. The
+   * operation is idempotent, so inserting the same slice twice will not change
+   * the state of the point. The markers are sorted by the slice ID.
+   *
+   * @param slice Slice to add to the marker list.
+   * @deprecated This method might happen to be not necessary.
+   */
+  public addMarker(slice: Slice): void {
+    /** @deprecated */
+    const markers = this.markers;
+    const length = markers.length;
+    if (!length) {
+      markers.push(slice);
+      return;
+    }
+    // We attempt to insert from the end of the list, as it is the most likely
+    // scenario. And `.push()` is more efficient than `.unshift()`.
+    const lastSlice = markers[length - 1];
+    const sliceId = slice.id;
+    const cmp = compare(lastSlice.id, sliceId);
+    if (cmp < 0) {
+      markers.push(slice);
+      return;
+    } else if (!cmp) return;
+    for (let i = length - 2; i >= 0; i--) {
+      const currSlice = markers[i];
+      const cmp = compare(currSlice.id, sliceId);
+      if (cmp < 0) {
+        markers.splice(i + 1, 0, slice);
+        return;
+      } else if (!cmp) return;
+    }
+    markers.unshift(slice);
+  }
+
+  /**
+   * Removes a slice from the list of markers, which represent a single point in
+   * the text, even if the start and end of the slice are different.
+   *
+   * @param slice Slice to remove from the marker list.
+   * @deprecated This method might happen to be not necessary.
+   */
+  public removeMarker(slice: Slice): void {
+    /** @deprecated */
+    const markers = this.markers;
+    const length = markers.length;
+    for (let i = 0; i < length; i++) {
+      if (markers[i] === slice) {
+        markers.splice(i, 1);
+        return;
+      }
+    }
+  }
+
+  // --------------------------------------------------------------------- refs
+
+  /**
+   * Sorted list of all references to rich-text constructs.
+   */
+  public readonly refs: OverlayRef[] = [];
+
+  /**
+   * Insert a reference to a marker.
+   *
+   * @param slice A marker (split slice).
+   */
+  public addMarkerRef(slice: SplitSlice): void {
+    this.refs.push(slice);
+    this.addMarker(slice);
+  }
+
+  /**
+   * Insert a layer that starts at this point.
+   *
+   * @param slice A slice that starts at this point.
+   */
+  public addLayerStartRef(slice: Slice): void {
+    this.refs.push(new OverlayRefSliceStart(slice));
+    this.addLayer(slice);
+  }
+
+  /**
+   * Insert a layer that ends at this point.
+   *
+   * @param slice A slice that ends at this point.
+   */
+  public addLayerEndRef(slice: Slice): void {
+    this.refs.push(new OverlayRefSliceEnd(slice));
+  }
+
+  /**
+   * Removes a reference to a marker or a slice, and remove the corresponding
+   * layer or marker.
+   *
+   * @param slice A slice to remove the reference to.
+   */
+  public removeRef(slice: Slice): void {
+    const refs = this.refs;
+    const length = refs.length;
+    for (let i = 0; i < length; i++) {
+      const ref = refs[i];
+      if (ref === slice) {
+        refs.splice(i, 1);
+        this.removeMarker(slice);
+        return;
+      }
+      if (
+        (ref instanceof OverlayRefSliceStart && ref.slice === slice) ||
+        (ref instanceof OverlayRefSliceEnd && ref.slice === slice)
+      ) {
+        refs.splice(i, 1);
+        this.removeLayer(slice);
+        return;
+      }
+    }
+  }
+
+  // ---------------------------------------------------------------- Printable
+
+  public toStringName(tab: string, lite?: boolean): string {
+    return super.toString(tab, lite);
+  }
+
+  public toString(tab: string = '', lite?: boolean): string {
+    const refs = lite ? '' : `, refs = ${this.refs.length}`;
+    const header = this.toStringName(tab, lite) + refs;
+    if (lite) return header;
+    return (
+      header +
+      printTree(
+        tab,
+        this.layers.map((slice) => (tab) => slice.toString(tab)),
+      )
+    );
+  }
+
+  // ------------------------------------------------------------- HeadlessNode
+
+  public p: OverlayPoint | undefined = undefined;
+  public l: OverlayPoint | undefined = undefined;
+  public r: OverlayPoint | undefined = undefined;
+}