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<?php // https://axenov.dev/php-trees-without-recursion/ // функция построения дерева без рекурсии function tree( array $flat_list, string $fk = 'hid', string $pk = 'id', ): array { $tree = []; foreach ($flat_list as &$node) { $references[$node[$pk]] = &$node; if (empty($node[$fk])) { $tree[$node[$pk]] = &$node; } else { $references[$node[$fk]]['children'][] = &$node; } } return $tree; } //============================================ // Кейс 1. Допустим, массив неассоциирован //============================================ // пример вспомогательной фукции для ассоциации массива function key_by_field(array $flat_list, string $pk = 'id'): array { $result = []; foreach ($flat_list as $element) { $result[$element[$pk]] = $element; } return $result; } // исходные данные $data = <<<JSON [ { "id": 1, "hid": null, "title": "Root" }, { "id": 2, "hid": 1, "title": "Branch 1" }, { "id": 3, "hid": 2, "title": "Leaf 1.1" }, { "id": 5, "hid": 1, "title": "Branch 2" }, { "id": 6, "hid": 5, "title": "Leaf 2.1" }, { "id": 4, "hid": 2, "title": "Leaf 1.2" }, { "id": 7, "hid": 5, "title": "Leaf 2.2" } ] JSON; $json = json_decode($data, JSON_OBJECT_AS_ARRAY | JSON_THROW_ON_ERROR); $json = key_by_field($json); // формирование нового списка элементов print_r(tree($json)); //============================================ // Кейс 2. Допустим, массив ассоциирован //============================================ $data2 = <<<JSON { "1": { "id": 1, "hid": null, "title": "Root" }, "3": { "id": 2, "hid": 2, "title": "Leaf 1.1" }, "2": { "id": 3, "hid": 1, "title": "Branch 1" }, "5": { "id": 5, "hid": 1, "title": "Branch 2" }, "6": { "id": 6, "hid": 5, "title": "Leaf 2.1" }, "4": { "id": 4, "hid": 2, "title": "Leaf 1.2" }, "7": { "id": 7, "hid": 5, "title": "Leaf 2.2" } } JSON; $json2 = json_decode($data2, JSON_OBJECT_AS_ARRAY | JSON_THROW_ON_ERROR); // формирование нового списка элементов print_r(tree($json2));