Online PHP editor | output for ubuKX

<?php $list = json_decode(<<<'JSON' [ { "TagId": 2, "ParentTagId": null, "Name": "women" }, { "TagId": 5, "ParentTagId": 2, "Name": "bottom" }, { "TagId": 4, "ParentTagId": 2, "Name": "top" }, { "TagId": 7, "ParentTagId": 4, "Name": "shirt" }, { "TagId": 8, "ParentTagId": 4, "Name": "tshirt" }, { "TagId": 12, "ParentTagId": 7, "Name": "longsleeve" }, { "TagId": 16, "ParentTagId": null, "Name": "men" } ] JSON ); class Trie implements getIterator { protected $parent; protected $children = []; public function insert(Node $node) { $node->parent = $this; $this->children[] = $node; } public function findById($id) { foreach($this->children as $childNode) { if ($childNode->TagId === $id) { return $childNode; } } } public function hasChildren() { return (bool) count($this->children); } public function getIterator() { return $this->children; } } class Node extends Trie { public function __construct(stdClass $obj) { foreach($obj as $p => $v) { $this->$p = $v; } } } $trie = new Trie; /* Insert all of the parentless nodes */ foreach($list as $n => $obj) { if (!$obj->ParentTagId) { $trie->insert(new Node($obj)); unset($list[$n]); } } /* Insert all of the child nodes */ foreach($list as $n => $obj) { $p = $trie->findById($obj->ParentTagId); if ($p) { $p->insert(new Node($obj)); unset($list[$n]); } } var_dump(json_encode($trie));