/**
 * Mode for the `walkTree` method.
 */
export declare enum WalkTreeMode {
    /**
     * The walk will be done parent (roots) first, then children.
     */
    ParentFirst = "parentFirst",
    /**
     * The walk will be done children (leafs) first, then parents.
     */
    ChildrenFirst = "childrenFirst"
}
/**
 * Walks a tree, running the predicate function for each node.
 * If the predicate function returns something other than undefined,
 * then the walk will be stopped and the function will return the returned value.
 *
 * @template T Returned node type, defaults to void.
 * @param root Subtree root node.
 * @param visit Function that will be run for each node of the tree.
 * @param mode Mode to walk the tree, as defined in `WalkTreeMode`.
 * @returns The value returned by the predicate function that stopped the walk,
 * or undefined if the walk was completed.
 */
export declare function walkTree<T = void>(root: object, visit: (node: object) => T | undefined, mode: WalkTreeMode): T | undefined;