Online PHP editor | output for U3h2Q

<?php class IteratorWithFilter { public $generator; public function __construct(array $data) { $this->generator = new \ArrayIterator($data); } public function filter() { $weakRef = WeakReference::create($this); $this->generator = new CallbackFilterIterator($this->generator, static function(array $row) use ($weakRef) { $filterObj = $weakRef->get(); return $filterObj->matchRow($row); }); $this->generator->filterObj = $this; // this assigment will link the objects exactly the same as if // bound function is passed directly, thus the WeakReference // will always be valid/nonGCed return $this; } public function matchRow(array $row) { return $row[0] === 'b'; } } function createIterator() { $iter = new IteratorWithFilter([['a'], ['b']]); return $iter->filter(); } for ($i = 0; $i < 10 * 1000; $i++) { $generator = createIterator()->generator; iterator_to_array($generator); // must success and always return ['b'] if (($i % 10) === 0) { gc_collect_cycles(); } if (($i % 1000) === 0) { echo round(memory_get_usage() / (1024 * 1024), 3) . " MiB\n"; } }