Tree Navigation

/**
 * Check if object has any children
 * Time Complexity: O(1)
 * @param {Object} object - Object to check
 * @returns {boolean} True if object has children, false otherwise
 */
hasChildren(object: Object): boolean;

/**
 * Get the first child of an object
 * Time Complexity: O(1)
 * @param {Object} object - Parent object
 * @returns {Object|null} First child object or null if no children
 */
firstChild(object: Object): Object | null;

/**
 * Get the last child of an object
 * Time Complexity: O(1)
 * @param {Object} object - Parent object
 * @returns {Object|null} Last child object or null if no children
 */
lastChild(object: Object): Object | null;

/**
 * Get the previous sibling of an object
 * Time Complexity: O(1)
 * @param {Object} object - Reference object
 * @returns {Object|null} Previous sibling object or null if none
 */
previousSibling(object: Object): Object | null;

/**
 * Get the next sibling of an object
 * Time Complexity: O(1)
 * @param {Object} object - Reference object
 * @returns {Object|null} Next sibling object or null if none
 */
nextSibling(object: Object): Object | null;

/**
 * Get the parent of an object
 * Time Complexity: O(1)
 * @param {Object} object - Child object
 * @returns {Object|null} Parent object or null if no parent
 */
parent(object: Object): Object | null;

const SymbolTree = require("symbol-tree");
const tree = new SymbolTree();

// Create a tree structure
const parent = { name: "parent" };
const child1 = { name: "child1" };
const child2 = { name: "child2" };
const grandchild = { name: "grandchild" };

tree.appendChild(parent, child1);
tree.appendChild(parent, child2);
tree.appendChild(child1, grandchild);

// Navigate the tree
console.log(tree.hasChildren(parent)); // true
console.log(tree.hasChildren(child1)); // true
console.log(tree.hasChildren(child2)); // false

// Access children
console.log(tree.firstChild(parent) === child1); // true
console.log(tree.lastChild(parent) === child2); // true

// Navigate siblings
console.log(tree.nextSibling(child1) === child2); // true
console.log(tree.previousSibling(child2) === child1); // true
console.log(tree.nextSibling(child2)); // null (no next sibling)

// Access parents
console.log(tree.parent(child1) === parent); // true
console.log(tree.parent(grandchild) === child1); // true
console.log(tree.parent(parent)); // null (no parent)

// Traverse an entire branch
function printBranch(node, indent = 0) {
  const spaces = " ".repeat(indent);
  console.log(spaces + node.name);
  
  for (let child = tree.firstChild(node); child; child = tree.nextSibling(child)) {
    printBranch(child, indent + 2);
  }
}

printBranch(parent);
// Output:
// parent
//   child1
//     grandchild
//   child2

const tree = new SymbolTree();

// Create a linked list
const nodeA = { value: "A" };
const nodeB = { value: "B" };
const nodeC = { value: "C" };

tree.insertBefore(nodeB, nodeA); // A -> B
tree.insertAfter(nodeB, nodeC);  // A -> B -> C

// Navigate the linked list
let current = nodeA;
while (current) {
  console.log(current.value);
  current = tree.nextSibling(current);
}
// Output: A, B, C

// Navigate backwards
current = nodeC;
while (current) {
  console.log(current.value);
  current = tree.previousSibling(current);
}
// Output: C, B, A