import { CommonTree } from "./CommonTree.js";
import type { TreeVisitorAction } from "./TreeVisitorAction.js";
/**
 * Do a depth first walk of a tree, applying pre() and post() actions as we discover and finish nodes.
 */
export declare class TreeVisitor {
    /**
     * Visit every node in tree t and trigger an action for each node before/after having visited all of its children.
     * Execute both actions even if t has no children. If a child visit yields a new child, it can update its
     * parent's child list or just return the new child. The  child update code works even if the child visit
     * alters its parent and returns the new tree.
     *
     * @param t The tree to visit.
     * @param action The action to trigger for each node.
     *
     * @returns The result of applying post action to this node.
     */
    visit(t: CommonTree, action?: TreeVisitorAction<CommonTree>): CommonTree;
}