public function diffFiltered(ChronosInterval $ci, callable $callback, ChronosInterface $dt = null, $abs = true)
{
$start = $this;
$end = $dt === null ? static::now($this->tz) : $dt;
$inverse = false;
if (defined('HHVM_VERSION')) {
$start = new DateTimeImmutable($this->toIso8601String());
$end = new DateTimeImmutable($end->toIso8601String());
}
if ($end < $start) {
$start = $end;
$end = $this;
$inverse = true;
}
$period = new DatePeriod($start, $ci, $end);
$vals = array_filter(iterator_to_array($period), function (DateTimeInterface $date) use($callback) {
return $callback(static::instance($date));
});
$diff = count($vals);
return $inverse && !$abs ? -$diff : $diff;
}