/*!
 * Copyright 2016 The ANTLR Project. All rights reserved.
 * Licensed under the BSD-3-Clause license. See LICENSE file in the project root for license information.
 */
/** The basic notion of a tree has a parent, a payload, and a list of children.
 *  It is the most abstract interface for all the trees used by ANTLR.
 */
export interface Tree {
    /** The parent of this node. If the return value is `undefined`, then this
     *  node is the root of the tree.
     */
    readonly parent: Tree | undefined;
    /**
     * This method returns whatever object represents the data at this node. For
     * example, for parse trees, the payload can be a {@link Token} representing
     * a leaf node or a {@link RuleContext} object representing a rule
     * invocation. For abstract syntax trees (ASTs), this is a {@link Token}
     * object.
     */
    readonly payload: {
        text?: string;
    };
    /**
     * If there are children, get the `i`th value indexed from 0. Throws a `RangeError` if `i` is less than zero, or
     * greater than or equal to `childCount`.
     */
    getChild(i: number): Tree;
    /** How many children are there? If there is none, then this
     *  node represents a leaf node.
     */
    readonly childCount: number;
    /** Print out a whole tree, not just a node, in LISP format
     *  `(root child1 .. childN)`. Print just a node if this is a leaf.
     */
    toStringTree(): string;
}