FluentDOM\Query::changeClassString PHP Method

    private function changeClassString($current, $toggle, $switch)
    {
        $currentClasses = array_flip(preg_split('(\\s+)', trim($current), 0, PREG_SPLIT_NO_EMPTY));
        $toggleClasses = array_unique(preg_split('(\\s+)', trim($toggle), 0, PREG_SPLIT_NO_EMPTY));
        $modified = FALSE;
        foreach ($toggleClasses as $class) {
            if (isset($currentClasses[$class]) && (NULL === $switch || FALSE === $switch)) {
                unset($currentClasses[$class]);
                $modified = TRUE;
            } elseif (NULL === $switch || TRUE === $switch) {
                $currentClasses[$class] = TRUE;
                $modified = TRUE;
            }
        }
        return $modified ? implode(' ', array_keys($currentClasses)) : FALSE;
    }