/**
 * Depth-first pre-order strategy (https://en.wikipedia.org/wiki/Tree_traversal#Pre-order_(NLR)).
 *
 * @type {string}
 */
export declare const TRAVERSAL_DF_PRE = "DF-pre-order";
/**
 * @param {Function} callback A callback which will be called on each visited node.
 * @param {*} context A context to pass through.
 * @returns {boolean}
 */
export declare function depthFirstPreOrder(this: TreeNode<object>, callback: Function, context: unknown): unknown;
/**
 * Depth-first post-order strategy (https://en.wikipedia.org/wiki/Tree_traversal#Post-order_(NLR)).
 *
 * @type {string}
 */
export declare const TRAVERSAL_DF_POST = "DF-post-order";
/**
 * Breadth-first traversal strategy (https://en.wikipedia.org/wiki/Tree_traversal#Breadth-first_search_/_level_order).
 *
 * @type {string}
 */
export declare const TRAVERSAL_BF = "BF";
/**
 * @template T
 */
export default class TreeNode<T extends object = Record<string, unknown>> {
    /**
     * A tree data.
     *
     * @type {object}
     */
    data: T;
    /**
     * A parent node.
     *
     * @type {TreeNode}
     */
    parent: TreeNode<T> | null;
    /**
     * A tree leaves.
     *
     * @type {TreeNode[]}
     */
    childs: TreeNode<T>[];
    /**
     * Initializes the tree node with the provided data object.
     */
    constructor(data: T);
    /**
     * Adds a node to tree leaves. Added node is linked with the parent node through "parent" property.
     *
     * @param {TreeNode} node A TreeNode to add.
     */
    addChild(node: TreeNode<T>): void;
    /**
     * @memberof TreeNode#
     * @function cloneTree
     *
     * Clones a tree structure deeply.
     *
     * For example, for giving a tree structure:
     *      .--(B1)--.
     *   .-(C1)   .-(C2)-.----.
     *  (D1)     (D2)   (D3) (D4)
     *
     * Cloning a tree starting from C2 node creates a mirrored tree structure.
     *     .-(C2')-.-----.
     *    (D2')   (D3') (D4')
     *
     * The cloned tree can be safely modified without affecting the original structure.
     * After modification, the clone can be merged with a tree using the "replaceTreeWith" method.
     *
     * @param {TreeNode} [nodeTree=this] A TreeNode to clone.
     * @returns {TreeNode}
     */
    cloneTree(nodeTree?: TreeNode<T>): TreeNode<T>;
    /**
     * Replaces the current node with a passed tree structure.
     *
     * @param {TreeNode} nodeTree A TreeNode to replace with.
     */
    replaceTreeWith(nodeTree: TreeNode<T>): void;
    /**
     * Traverses the tree structure through node childs. The walk down traversing supports
     * a three different strategies.
     *  - Depth-first pre-order strategy (https://en.wikipedia.org/wiki/Tree_traversal#Pre-order_(NLR));
     *  - Depth-first post-order strategy (https://en.wikipedia.org/wiki/Tree_traversal#Post-order_(NLR));
     *  - Breadth-first traversal strategy (https://en.wikipedia.org/wiki/Tree_traversal#Breadth-first_search_/_level_order).
     *
     * @param {Function} callback The callback function which will be called for each node.
     * @param {string} [traversalStrategy=DEFAULT_TRAVERSAL_STRATEGY] Traversing strategy.
     */
    walkDown(callback: (node: TreeNode<T>) => unknown, traversalStrategy?: string): void;
    /**
     * Traverses the tree structure through node parents.
     *
     * @param {Function} callback The callback function which will be called for each node.
     */
    walkUp(callback: (this: TreeNode<T>, node: TreeNode<T>) => boolean | void): void;
}