3v4l.org

run code in 300+ PHP versions simultaneously
<?php preg_match('/(?>[A-Za-z]+)::([A-Za-z]+)/', 'Foo::Bar', $m); var_dump($m); preg_match('/([A-Za-z]++)::([A-Za-z]+)/', 'Foo::Bar', $m); var_dump($m);

preferences:
35.16 ms | 402 KiB | 5 Q