structural none linear data

none-linear-tree-node.php

<?php
class TreeNode
{
    public function __construct(public readonly string $value, public readonly ?TreeNode $left = null, public readonly ?TreeNode $right = null)
    {
    }

    public function makeRightAsTreeNodeThenDo(TreeNode $right, callable $result): void
    {
        $result(new self($this->value, $this->left, $right));
    }
}

class AggregateTreeNode
{
    public function __construct(public readonly TreeNode $root)
    {
    }
}

// Structural non linear data
$root = new TreeNode('root');
$node1 = new TreeNode('foo', $root);
$node2 = new TreeNode('bar', $node1);

$node1->makeRightAsTreeNodeThenDo($node2, function (TreeNode $res) use (&$node1) {
    $node1 = $res;
});

$root->makeRightAsTreeNodeThenDo($node1, function (TreeNode $res) use (&$root) {
    $root = $res;
});

$tree = new AggregateTreeNode($root);

$node = $tree->root;

// We always have the root tree node
do {
    echo $node->value;
    $node = $node->right;
} while($node);