tree without recursion

CategoryRepository.php

function buildTree($data, $parentID = 0) {

        // build a tree using references and not recursion
        $references = array();
        $tree = array();

        foreach ($data as $id=> &$node) {
            // Use id as key to make a references to the tree and initialize it with node reference.
            $references[$node['id']] = &$node;

            // Add empty array to hold the children/subcategories
            $node['children'] = array();

            // Get your root node and add this directly to the tree
            if ($node['parentID']==$parentID) {
                $tree[$node['id']] = &$node;
            } else {
                // Add the non-root node to its parent's references
                $references[$node['parentID']]['children'][$node['id']] = &$node;
            }
        }
        return $tree;
    }