Online PHP editor | output for trdBX

<?php $data = []; $data['x'] = ['x_v']; $data['y'] = ['y_v']; $gen = new \ArrayIterator($data); var_dump($gen->valid()); var_dump($gen->current()); $filterFx = function ($row) { return count($row) !== false; // always true }; $genOrig = $gen; $gen = new \CallbackFilterIterator($gen, $filterFx); $genOrig->next(); // has correctly no effect // $gen->rewind(); // must be called, iterator is not initialized by default var_dump($gen->valid()); var_dump($gen->current()); var_dump($gen->valid()); var_dump($gen->next());