Method _getTreeStructure

src/aria/tree/testing/tree-harness.ts:54–97

* Recursively collect the structured text of the tree items. * @param items A list of tree items * @param level The level of items that are being accounted for during this iteration * @param parentExpanded Whether the parent of the first item in param items is expanded

(
    items: [number, string, boolean][],
    level: number,
    parentExpanded: boolean,
  )

   * @param parentExpanded Whether the parent of the first item in param items is expanded
   */
  private _getTreeStructure(
    items: [number, string, boolean][],
    level: number,
    parentExpanded: boolean,
  ): TextTree {
    const result: TextTree = {};
    for (let i = 0; i < items.length; i++) {
      const [itemLevel, text, expanded] = items[i];
      const nextItemLevel = items[i + 1]?.[0] ?? -1;

      // Return the accumulated value for the current level once we reach a shallower level item
      if (itemLevel < level) {
        return result;
      }
      // Skip deeper level items during this iteration, they will be picked up in a later iteration
      if (itemLevel > level) {
        continue;
      }
      // Only add to representation if it is visible (parent is expanded)
      if (parentExpanded) {
        // Collect the data under this item according to the following rules:
        // 1. If the next item in the list is a sibling of the current item add it to the child list
        // 2. If the next item is a child of the current item, get the sub-tree structure for the
        //    child and add it under this item
        // 3. If the next item has a shallower level, we've reached the end of the child items for
        //    the current parent.
        if (nextItemLevel === level) {
          this._addChildToItem(result, {text});
        } else if (nextItemLevel > level) {
          let children = this._getTreeStructure(
            items.slice(i + 1),
            nextItemLevel,
            expanded,
          )?.children;
          let child = children ? {text, children} : {text};
          this._addChildToItem(result, child);
        } else {
          this._addChildToItem(result, {text});
          return result;
        }
      }
    }
    return result;
  }

  private _addChildToItem(result: TextTree, child: TextTree) {
    result.children ? result.children.push(child) : (result.children = [child]);