private function processDirection($currentDirection)
{
switch (strtolower($currentDirection)) {
case self::MOVE_LEFT:
$this->currentVisitor->moveLeft();
break;
case self::MOVE_RIGHT:
$this->currentVisitor->moveRight();
break;
case self::MOVE_UP:
$this->currentVisitor->moveUp();
break;
case self::MOVE_DOWN:
$this->currentVisitor->moveDown();
break;
}
}