utility::string_t datetime::to_string()

in Include/json_cpp/details/asyncrt_utils.hpp [530:657]

• 106 lines of code
• 14 McCabe index (conditional complexity)

utility::string_t datetime::to_string(date_format format) const
{
#ifdef _WIN32
    int status;

    ULARGE_INTEGER largeInt;
    largeInt.QuadPart = m_interval;

    FILETIME ft;
    ft.dwHighDateTime = largeInt.HighPart;
    ft.dwLowDateTime = largeInt.LowPart;

    SYSTEMTIME systemTime;
    if (!FileTimeToSystemTime((const FILETIME *)&ft, &systemTime))
    {
        throw utility::details::create_system_error(GetLastError());
    }

    std::wostringstream outStream;
    outStream.imbue(std::locale::classic());

    if (format == RFC_1123)
    {
#if _WIN32_WINNT < _WIN32_WINNT_VISTA
        TCHAR dateStr[18] = {0};
        status = GetDateFormat(LOCALE_INVARIANT, 0, &systemTime, __TEXT("ddd',' dd MMM yyyy"), dateStr, sizeof(dateStr) / sizeof(TCHAR));
#else
        wchar_t dateStr[18] = {0};
        status = GetDateFormatEx(LOCALE_NAME_INVARIANT, 0, &systemTime, L"ddd',' dd MMM yyyy", dateStr, sizeof(dateStr) / sizeof(wchar_t), NULL);
#endif // _WIN32_WINNT < _WIN32_WINNT_VISTA
        if (status == 0)
        {
            throw utility::details::create_system_error(GetLastError());
        }

#if _WIN32_WINNT < _WIN32_WINNT_VISTA
        TCHAR timeStr[10] = {0};
        status = GetTimeFormat(LOCALE_INVARIANT, TIME_NOTIMEMARKER | TIME_FORCE24HOURFORMAT, &systemTime, __TEXT("HH':'mm':'ss"), timeStr, sizeof(timeStr) / sizeof(TCHAR));
#else
        wchar_t timeStr[10] = {0};
        status = GetTimeFormatEx(LOCALE_NAME_INVARIANT, TIME_NOTIMEMARKER | TIME_FORCE24HOURFORMAT, &systemTime, L"HH':'mm':'ss", timeStr, sizeof(timeStr) / sizeof(wchar_t));
#endif // _WIN32_WINNT < _WIN32_WINNT_VISTA
        if (status == 0)
        {
            throw utility::details::create_system_error(GetLastError());
        }

        outStream << dateStr << " " << timeStr << " " << "GMT";
    }
    else if (format == ISO_8601)
    {
        const size_t buffSize = 64;
#if _WIN32_WINNT < _WIN32_WINNT_VISTA
        TCHAR dateStr[buffSize] = {0};
        status = GetDateFormat(LOCALE_INVARIANT, 0, &systemTime, __TEXT("yyyy-MM-dd"), dateStr, buffSize);
#else
        wchar_t dateStr[buffSize] = {0};
        status = GetDateFormatEx(LOCALE_NAME_INVARIANT, 0, &systemTime, L"yyyy-MM-dd", dateStr, buffSize, NULL);
#endif // _WIN32_WINNT < _WIN32_WINNT_VISTA
        if (status == 0)
        {
            throw utility::details::create_system_error(GetLastError());
        }

#if _WIN32_WINNT < _WIN32_WINNT_VISTA
        TCHAR timeStr[buffSize] = {0};
        status = GetTimeFormat(LOCALE_INVARIANT, TIME_NOTIMEMARKER | TIME_FORCE24HOURFORMAT, &systemTime, __TEXT("HH':'mm':'ss"), timeStr, buffSize);
#else
        wchar_t timeStr[buffSize] = {0};
        status = GetTimeFormatEx(LOCALE_NAME_INVARIANT, TIME_NOTIMEMARKER | TIME_FORCE24HOURFORMAT, &systemTime, L"HH':'mm':'ss", timeStr, buffSize);
#endif // _WIN32_WINNT < _WIN32_WINNT_VISTA
        if (status == 0)
        {
            throw utility::details::create_system_error(GetLastError());
        }

        outStream << dateStr << "T" << timeStr;
        uint64_t frac_sec = largeInt.QuadPart % _secondTicks;
        if (frac_sec > 0)
        {
            // Append fractional second, which is a 7-digit value with no trailing zeros
            // This way, '1200' becomes '00012'
            char buf[9] = { 0 };
            sprintf_s(buf, sizeof(buf), ".%07ld", (long int)frac_sec);
            // trim trailing zeros
            for (int i = 7; buf[i] == '0'; i--) buf[i] = '\0';
            outStream << buf;
        }
        outStream << "Z";
    }

    return outStream.str();
#else //LINUX
    uint64_t input = m_interval;
    uint64_t frac_sec = input % _secondTicks;
    input /= _secondTicks; // convert to seconds
    time_t time = (time_t)input - (time_t)11644473600LL;// diff between windows and unix epochs (seconds)

    struct tm datetime;
    gmtime_r(&time, &datetime);

    const int max_dt_length = 64;
    char output[max_dt_length+1] = {0};

    if (format != RFC_1123 && frac_sec > 0)
    {
        // Append fractional second, which is a 7-digit value with no trailing zeros
        // This way, '1200' becomes '00012'
        char buf[9] = { 0 };
        snprintf(buf, sizeof(buf), ".%07ld", (long int)frac_sec);
        // trim trailing zeros
        for (int i = 7; buf[i] == '0'; i--) buf[i] = '\0';
        // format the datetime into a separate buffer
        char datetime_str[max_dt_length+1] = {0};
        strftime(datetime_str, sizeof(datetime_str), "%Y-%m-%dT%H:%M:%S", &datetime);
        // now print this buffer into the output buffer
        snprintf(output, sizeof(output), "%s%sZ", datetime_str, buf);
    }
    else
    {
        strftime(output, sizeof(output),
            format == RFC_1123 ? "%a, %d %b %Y %H:%M:%S GMT" : "%Y-%m-%dT%H:%M:%SZ",
            &datetime);
    }

    return std::string(output);
#endif
}