import { Id } from "./types.js";
/**
 * Tree of nestable things.
 *  - Things can have multiple children.
 *  - Things can only have one parent.
 *  - Things can be orphans (bring your own concept of a "root").
 */
export declare class Hierarchy {
    #private;
    has(id: Id): boolean;
    getChildren(id: Id): Set<string>;
    getParent(id: Id): string | undefined;
    /** establish an id as a root with no parents, but ready to accept children */
    establishRoot(root: Id): void;
    /** give a parent some children  */
    attach(parent: Id, ...children: Id[]): void;
    /** detach this id from its parent in the hierarchy */
    detach(id: Id): undefined;
    /** destroy all relations associated with this id, and all its descendants */
    destroy(id: Id): void;
    /** iterate over this id and all its descendants */
    crawl(id: Id, predicate?: (id: Id, path: Id[]) => boolean): Generator<[string, string[]], void, unknown>;
}