<?php
$str = 'mes "teste de mensagem";
input "blablabla";
switch("este é um":"placeholder");
end script;';
$regex = '/[.*\n]?"(.+?)"[.*\n]?(?1)*?/';
//preg_match($regex, $str, $matches);
PD9waHAKCiRzdHIgPSAnbWVzICJ0ZXN0ZSBkZSBtZW5zYWdlbSI7CmlucHV0ICJibGFibGFibGEiOwpzd2l0Y2goImVzdGUgw6kgdW0iOiJwbGFjZWhvbGRlciIpOwplbmQgc2NyaXB0Oyc7CgoKJHJlZ2V4ID0gJy9bLipcbl0/IiguKz8pIlsuKlxuXT8oPzEpKj8vJzsKCi8vcHJlZ19tYXRjaCgkcmVnZXgsICRzdHIsICRtYXRjaGVzKTsKcHJlZ19tYXRjaF9hbGwoJHJlZ2V4LCAkc3RyLCAkbWF0Y2hlcyk7CgpwcmludF9yKCRtYXRjaGVzKTs=