private int readEscapeChar() {
        int c = getc();
        if (c == 'n')
            c = '\n';
        else if (c == 't')
            c = '\t';
        else if (c == 'r')
            c = '\r';
        else if (c == 'f')
            c = '\f';
        else if (c == '\n')
            ++lineNumber;

        return c;
    }