private function parseSubjectByCharacter()
    {
        $i = 0;
        foreach (preg_split('//u', $this->subject) as $currentCharacter) {
            if ($currentCharacter === '') {
                continue;
            }
            $this->iteratorCache->append(new TextIteratorElement($currentCharacter, $i, 1, false));
            $i++;
        }
    }