formats.exposed/public/common/nodePath.js

// @ts-check

/**
 * A node path is an array of indices that can traverse a Node tree.
 *
 * For example, given the following tree:
 *
 * ```javascript
 * {
 *   name: "top",
 *   children: [
 *     { name: "first" },
 *     { name: "second", children: [{ name: "grandchild" }] },
 *   ],
 * }
 * ```
 *
 * `[]` is "top", `[0]` is "first", `[1]` is "second", and `[1, 0]` is "grandchild".
 *
 * @typedef {number[]} NodePath
 */

/**
 * @param {unknown} value
 * @returns {null | NodePath} The parsed node path, or null if invalid.
 */
export const parse = (value) => {
  if (typeof value !== "string") return null;
  if (!value) return [];
  return value.split(",").map((str) => {
    const result = parseInt(str, 10);
    if (Number.isFinite(result)) return result;
    throw new Error(`Invalid node path: ${value}`);
  });
};

/**
 * @param {NodePath} a
 * @param {NodePath} b
 * @returns {boolean}
 */
export const isEqualTo = (a, b) => a.length === b.length && isSupersetOf(a, b);

/**
 * @param {NodePath} smaller
 * @param {NodePath} bigger
 * @returns {boolean}
 */
export const isSupersetOf = (smaller, bigger) => {
  for (let i = 0; i < smaller.length; i++) {
    if (smaller[i] !== bigger[i]) return false;
  }
  return true;
};