private function nextChar()
    {
        if( ! $this->isEOF())
        {
            $this->linePos ++;

            return $this->input[$this->pos++];
        }
        return null;
    }
private function nextChar()
    {
        if( ! $this->isEOF())
        {
            $this->linePos ++;

            return $this->input[$this->pos++];
        }
        return null;
    }
private function nextChar ( ) { if ( ! $ this -> isEOF ( ) ) { $ this -> linePos ++ ; return $ this -> input [ $ this -> pos ++ ] ; } return null ; }
Returns current char,
then moves pointer.

@return string|null
Returns current char then moves pointer .