]> git.saurik.com Git - wxWidgets.git/blobdiff - src/common/datetime.cpp
test for timegm() added
[wxWidgets.git] / src / common / datetime.cpp
index 6161193d34555c7c362a8d002455329226f3a41b..09215a759268c9e7ccc0e0d734d2f320915526c9 100644 (file)
     #include "wx/log.h"
 #endif // WX_PRECOMP
 
+#include "wx/thread.h"
+
+#define wxDEFINE_TIME_CONSTANTS
+
 #include "wx/datetime.h"
 
+// ----------------------------------------------------------------------------
+// constants
+// ----------------------------------------------------------------------------
+
+// some trivial ones
+static const int MONTHS_IN_YEAR = 12;
+
+static const int SECONDS_IN_MINUTE = 60;
+
+static const long SECONDS_PER_DAY = 86400l;
+
+static const long MILLISECONDS_PER_DAY = 86400000l;
+
+// this is the integral part of JDN of the midnight of Jan 1, 1970
+// (i.e. JDN(Jan 1, 1970) = 2440587.5)
+static const int EPOCH_JDN = 2440587;
+
+// ----------------------------------------------------------------------------
+// globals
+// ----------------------------------------------------------------------------
+
+// a critical section is needed to protect GetTimeZone() static
+// variable in MT case
+#ifdef wxUSE_THREADS
+    wxCriticalSection gs_critsectTimezone;
+#endif // wxUSE_THREADS
+
+// ----------------------------------------------------------------------------
+// private functions
+// ----------------------------------------------------------------------------
+
+// get the number of days in the given month of the given year
+static inline
+wxDateTime::wxDateTime_t GetNumOfDaysInMonth(int year, wxDateTime::Month month)
+{
+    // the number of days in month in Julian/Gregorian calendar: the first line
+    // is for normal years, the second one is for the leap ones
+    static wxDateTime::wxDateTime_t daysInMonth[2][MONTHS_IN_YEAR] =
+    {
+        { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
+        { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
+    };
+
+    return daysInMonth[wxDateTime::IsLeapYear(year)][month];
+}
+
+// ensure that the timezone variable is set by calling localtime
+static int GetTimeZone()
+{
+    // set to TRUE when the timezone is set
+    static bool s_timezoneSet = FALSE;
+
+    wxCRIT_SECT_LOCKER(lock, gs_critsectTimezone);
+
+    if ( !s_timezoneSet )
+    {
+        // just call localtime() instead of figurin out whether this system
+        // supports tzset(), _tzset() or something else
+        time_t t;
+        (void)localtime(&t);
+
+        s_timezoneSet = TRUE;
+    }
+
+    return (int)timezone;
+}
+
+// return the integral part of the JDN for the midnight of the given date (to
+// get the real JDN you need to add 0.5, this is, in fact, JDN of the noon of
+// the previous day)
+static long GetTruncatedJDN(wxDateTime::wxDateTime_t day,
+                            wxDateTime::Month mon,
+                            int year)
+{
+    // CREDIT: the algorithm was taken from Peter Baum's home page
+
+    // the algorithm assumes Jan == 1
+    int month = mon + 1;
+
+    // we want the leap day (Feb 29) be at the end of the year, so we count
+    // March as the first month
+    if ( month < wxDateTime::Mar + 1 )
+    {
+        month += MONTHS_IN_YEAR;
+        year--;
+    }
+
+    // this table contains the number of the days before the 1st of the each
+    // month (in a non leap year) with the third value corresponding to March
+    // (and the last one to February)
+    static const int monthOffsets[14] =
+    {
+        0, 31, 61, 92, 122, 153, 184, 214, 245, 275, 306
+    };
+
+    // and now add contributions of all terms together to get the result (you'd
+    // better see the Web page for the description if you want to understand
+    // why it works (if it does :-))
+    return day +
+           // linear approximation for months
+           monthOffsets[month - (wxDateTime::Mar + 1)] +
+           // the year contribution
+           365*year + year/4 - year/100 + year/400 +
+           // 1721119.5 is the JDN of the midnight of Mar 1, year 0
+           1721118;
+}
+
+// this function is a wrapper around strftime(3)
+static wxString CallStrftime(const wxChar *format, const tm* tm)
+{
+    wxChar buf[1024];
+    if ( !wxStrftime(buf, WXSIZEOF(buf), format, tm) )
+    {
+        // is ti really possible that 1024 is too short?
+        wxFAIL_MSG(_T("strftime() failed"));
+    }
+
+    return wxString(buf);
+}
+
+// if year and/or month have invalid values, replace them with the current ones
+static void ReplaceDefaultYearMonthWithCurrent(int *year,
+                                               wxDateTime::Month *month)
+{
+    struct tm *tmNow = NULL;
+
+    if ( *year == wxDateTime::Inv_Year )
+    {
+        tmNow = wxDateTime::GetTmNow();
+
+        *year = 1900 + tmNow->tm_year;
+    }
+
+    if ( *month == wxDateTime::Inv_Month )
+    {
+        if ( !tmNow )
+            tmNow = wxDateTime::GetTmNow();
+
+        *month = (wxDateTime::Month)tmNow->tm_mon;
+    }
+}
+
 // ============================================================================
 // implementation of wxDateTime
 // ============================================================================
 // static data
 // ----------------------------------------------------------------------------
 
-Country wxDateTime::ms_country;
+wxDateTime::Country wxDateTime::ms_country = wxDateTime::Country_Unknown;
 wxDateTime wxDateTime::ms_InvDateTime;
 
+// ----------------------------------------------------------------------------
+// struct Tm
+// ----------------------------------------------------------------------------
+
+wxDateTime::Tm::Tm()
+{
+    year = (wxDateTime_t)wxDateTime::Inv_Year;
+    mon = wxDateTime::Inv_Month;
+    mday = 0;
+    hour = min = sec = msec = 0;
+    wday = wxDateTime::Inv_WeekDay;
+}
+
+wxDateTime::Tm::Tm(const struct tm& tm)
+{
+    msec = 0;
+    sec = tm.tm_sec;
+    min = tm.tm_min;
+    hour = tm.tm_hour;
+    mday = tm.tm_mday;
+    mon = (wxDateTime::Month)tm.tm_mon;
+    year = 1900 + tm.tm_year;
+    wday = tm.tm_wday;
+    yday = tm.tm_yday;
+}
+
+bool wxDateTime::Tm::IsValid() const
+{
+    // we allow for the leap seconds, although we don't use them (yet)
+    return (year != wxDateTime::Inv_Year) && (mon != wxDateTime::Inv_Month) &&
+           (mday < GetNumOfDaysInMonth(year, mon)) &&
+           (hour < 24) && (min < 60) && (sec < 62) && (msec < 1000);
+}
+
+void wxDateTime::Tm::ComputeWeekDay()
+{
+    wxFAIL_MSG(_T("TODO"));
+}
+
+void wxDateTime::Tm::AddMonths(int monDiff)
+{
+    // normalize the months field
+    while ( monDiff < -mon )
+    {
+        year--;
+
+        monDiff += MONTHS_IN_YEAR;
+    }
+
+    while ( monDiff + mon > MONTHS_IN_YEAR )
+    {
+        year++;
+    }
+
+    mon = (wxDateTime::Month)(mon + monDiff);
+
+    wxASSERT_MSG( mon >= 0 && mon < MONTHS_IN_YEAR, _T("logic error") );
+}
+
+void wxDateTime::Tm::AddDays(int dayDiff)
+{
+    // normalize the days field
+    mday += dayDiff;
+    while ( mday < 1 )
+    {
+        AddMonths(-1);
+
+        mday += GetNumOfDaysInMonth(year, mon);
+    }
+
+    while ( mday > GetNumOfDaysInMonth(year, mon) )
+    {
+        mday -= GetNumOfDaysInMonth(year, mon);
+
+        AddMonths(1);
+    }
+
+    wxASSERT_MSG( mday > 0 && mday <= GetNumOfDaysInMonth(year, mon),
+                  _T("logic error") );
+}
+
+// ----------------------------------------------------------------------------
+// class TimeZone
+// ----------------------------------------------------------------------------
+
+wxDateTime::TimeZone::TimeZone(wxDateTime::TZ tz)
+{
+    switch ( tz )
+    {
+        case wxDateTime::Local:
+            // leave offset to be 0
+            break;
+
+        case wxDateTime::GMT_12:
+        case wxDateTime::GMT_11:
+        case wxDateTime::GMT_10:
+        case wxDateTime::GMT_9:
+        case wxDateTime::GMT_8:
+        case wxDateTime::GMT_7:
+        case wxDateTime::GMT_6:
+        case wxDateTime::GMT_5:
+        case wxDateTime::GMT_4:
+        case wxDateTime::GMT_3:
+        case wxDateTime::GMT_2:
+        case wxDateTime::GMT_1:
+            m_offset = -60*(wxDateTime::GMT0 - tz);
+            break;
+
+        case wxDateTime::GMT0:
+        case wxDateTime::GMT1:
+        case wxDateTime::GMT2:
+        case wxDateTime::GMT3:
+        case wxDateTime::GMT4:
+        case wxDateTime::GMT5:
+        case wxDateTime::GMT6:
+        case wxDateTime::GMT7:
+        case wxDateTime::GMT8:
+        case wxDateTime::GMT9:
+        case wxDateTime::GMT10:
+        case wxDateTime::GMT11:
+        case wxDateTime::GMT12:
+            m_offset = 60*(tz - wxDateTime::GMT0);
+            break;
+
+        case wxDateTime::A_CST:
+            // Central Standard Time in use in Australia = UTC + 9.5
+            m_offset = 9*60 + 30;
+            break;
+
+        default:
+            wxFAIL_MSG( _T("unknown time zone") );
+    }
+}
+
+// ----------------------------------------------------------------------------
+// static functions
+// ----------------------------------------------------------------------------
+
+/* static */
+bool wxDateTime::IsLeapYear(int year, wxDateTime::Calendar cal)
+{
+    if ( year == Inv_Year )
+        year = GetCurrentYear();
+
+    if ( cal == Gregorian )
+    {
+        // in Gregorian calendar leap years are those divisible by 4 except
+        // those divisible by 100 unless they're also divisible by 400
+        // (in some countries, like Russia and Greece, additional corrections
+        // exist, but they won't manifest themselves until 2700)
+        return (year % 4 == 0) && ((year % 100 != 0) || (year % 400 == 0));
+    }
+    else if ( cal == Julian )
+    {
+        // in Julian calendar the rule is simpler
+        return year % 4 == 0;
+    }
+    else
+    {
+        wxFAIL_MSG(_T("unknown calendar"));
+
+        return FALSE;
+    }
+}
+
+/* static */
+int wxDateTime::GetCentury(int year)
+{
+    return year > 0 ? year / 100 : year / 100 - 1;
+}
+
+/* static */
+void wxDateTime::SetCountry(wxDateTime::Country country)
+{
+    ms_country = country;
+}
+
+/* static */
+int wxDateTime::ConvertYearToBC(int year)
+{
+    // year 0 is BC 1
+    return year > 0 ? year : year - 1;
+}
+
+/* static */
+int wxDateTime::GetCurrentYear(wxDateTime::Calendar cal)
+{
+    switch ( cal )
+    {
+        case Gregorian:
+            return Now().GetYear();
+
+        case Julian:
+            wxFAIL_MSG(_T("TODO"));
+            break;
+
+        default:
+            wxFAIL_MSG(_T("unsupported calendar"));
+            break;
+    }
+
+    return Inv_Year;
+}
+
+/* static */
+wxDateTime::Month wxDateTime::GetCurrentMonth(wxDateTime::Calendar cal)
+{
+    switch ( cal )
+    {
+        case Gregorian:
+            return Now().GetMonth();
+            break;
+
+        case Julian:
+            wxFAIL_MSG(_T("TODO"));
+            break;
+
+        default:
+            wxFAIL_MSG(_T("unsupported calendar"));
+            break;
+    }
+
+    return Inv_Month;
+}
+
+/* static */
+wxDateTime::wxDateTime_t wxDateTime::GetNumberOfDays(int year, Calendar cal)
+{
+    if ( year == Inv_Year )
+    {
+        // take the current year if none given
+        year = GetCurrentYear();
+    }
+
+    switch ( cal )
+    {
+        case Gregorian:
+        case Julian:
+            return IsLeapYear(year) ? 366 : 365;
+            break;
+
+        default:
+            wxFAIL_MSG(_T("unsupported calendar"));
+            break;
+    }
+
+    return 0;
+}
+
+/* static */
+wxDateTime::wxDateTime_t wxDateTime::GetNumberOfDays(wxDateTime::Month month,
+                                                     int year,
+                                                     wxDateTime::Calendar cal)
+{
+    wxCHECK_MSG( month < MONTHS_IN_YEAR, 0, _T("invalid month") );
+
+    if ( cal == Gregorian || cal == Julian )
+    {
+        if ( year == Inv_Year )
+        {
+            // take the current year if none given
+            year = GetCurrentYear();
+        }
+
+        return GetNumOfDaysInMonth(year, month);
+    }
+    else
+    {
+        wxFAIL_MSG(_T("unsupported calendar"));
+
+        return 0;
+    }
+}
+
+/* static */
+wxString wxDateTime::GetMonthName(wxDateTime::Month month, bool abbr)
+{
+    wxCHECK_MSG( month != Inv_Month, _T(""), _T("invalid month") );
+
+    tm tm = { 0, 0, 0, 1, month, 76 };  // any year will do
+
+    return CallStrftime(abbr ? _T("%b") : _T("%B"), &tm);
+}
+
+/* static */
+wxString wxDateTime::GetWeekDayName(wxDateTime::WeekDay wday, bool abbr)
+{
+    wxCHECK_MSG( wday != Inv_WeekDay, _T(""), _T("invalid weekday") );
+
+    // take some arbitrary Sunday
+    tm tm = { 0, 0, 0, 28, Nov, 99 };
+
+    // and offset it by the number of days needed to get 
+    tm.tm_mday += wday;
+
+    return CallStrftime(abbr ? _T("%a") : _T("%A"), &tm);
+}
+
 // ----------------------------------------------------------------------------
 // constructors and assignment operators
 // ----------------------------------------------------------------------------
 
-wxDateTime& wxDateTime::Set(const struct tm& tm)
+wxDateTime& wxDateTime::Set(const struct tm& tm1)
 {
-    time_t timet = mktime(tm);
+    wxASSERT_MSG( IsValid(), _T("invalid wxDateTime") );
+
+    tm tm2(tm1);
+    time_t timet = mktime(&tm2);
     if ( timet == (time_t)(-1) )
     {
         wxFAIL_MSG(_T("Invalid time"));
@@ -71,6 +518,8 @@ wxDateTime& wxDateTime::Set(wxDateTime_t hour,
                             wxDateTime_t second,
                             wxDateTime_t millisec)
 {
+    wxASSERT_MSG( IsValid(), _T("invalid wxDateTime") );
+
     // we allow seconds to be 61 to account for the leap seconds, even if we
     // don't use them really
     wxCHECK_MSG( hour < 24 && second < 62 && minute < 60 && millisec < 1000,
@@ -86,7 +535,7 @@ wxDateTime& wxDateTime::Set(wxDateTime_t hour,
     tm->tm_min = minute;
     tm->tm_sec = second;
 
-    (void)Set(tm);
+    (void)Set(*tm);
 
     // and finally adjust milliseconds
     return SetMillisecond(millisec);
@@ -100,16 +549,15 @@ wxDateTime& wxDateTime::Set(wxDateTime_t day,
                             wxDateTime_t second,
                             wxDateTime_t millisec)
 {
+    wxASSERT_MSG( IsValid(), _T("invalid wxDateTime") );
+
     wxCHECK_MSG( hour < 24 && second < 62 && minute < 60 && millisec < 1000,
                  ms_InvDateTime,
                  _T("Invalid time in wxDateTime::Set()") );
 
-    if ( year == Inv_Year )
-        year = GetCurrentYear();
-    if ( month == Inv_Month )
-        month = GetCurrentMonth();
+    ReplaceDefaultYearMonthWithCurrent(&year, &month);
 
-    wxCHECK_MSG( day < GetNumberOfDays(month, year), ms_InvDateTime,
+    wxCHECK_MSG( day <= GetNumberOfDays(month, year), ms_InvDateTime,
                  _T("Invalid date in wxDateTime::Set()") );
 
     // the range of time_t type (inclusive)
@@ -118,12 +566,12 @@ wxDateTime& wxDateTime::Set(wxDateTime_t day,
 
     // test only the year instead of testing for the exact end of the Unix
     // time_t range - it doesn't bring anything to do more precise checks
-    if ( year >= yearMaxInRange && year <= yearMaxInRange )
+    if ( year >= yearMinInRange && year <= yearMaxInRange )
     {
         // use the standard library version if the date is in range - this is
-        // probably much more efficient than our code
+        // probably more efficient than our code
         struct tm tm;
-        tm.tm_year = year;
+        tm.tm_year = year - 1900;
         tm.tm_mon = month;
         tm.tm_mday = day;
         tm.tm_hour = hour;
@@ -138,9 +586,461 @@ wxDateTime& wxDateTime::Set(wxDateTime_t day,
     else
     {
         // do time calculations ourselves: we want to calculate the number of
-        // milliseconds between the given date and the epoch (necessarily
-        // negative)
+        // milliseconds between the given date and the epoch
+
+        // get the JDN for the midnight of this day
+        m_time = GetTruncatedJDN(day, month, year);
+        m_time -= EPOCH_JDN;
+        m_time *= SECONDS_PER_DAY * TIME_T_FACTOR;
+
+        Add(wxTimeSpan(hour, minute, second, millisec));
     }
 
     return *this;
 }
+
+wxDateTime& wxDateTime::Set(double jdn)
+{
+    m_time = (jdn - 0.5 - EPOCH_JDN) * TIME_T_FACTOR;
+
+    return *this;
+}
+
+// ----------------------------------------------------------------------------
+// time_t <-> broken down time conversions
+// ----------------------------------------------------------------------------
+
+wxDateTime::Tm wxDateTime::GetTm() const
+{
+    wxASSERT_MSG( IsValid(), _T("invalid wxDateTime") );
+
+    time_t time = GetTicks();
+    if ( time != (time_t)-1 )
+    {
+        // use C RTL functions
+        tm *tm = localtime(&time);
+
+        // should never happen
+        wxCHECK_MSG( tm, Tm(), _T("localtime() failed") );
+
+        return Tm(*tm);
+    }
+    else
+    {
+        // CREDIT: the algorithm was taken from Peter Baum's home page
+
+        // calculate the Gregorian date from JDN for the midnight of our date
+        wxLongLong timeMidnight = m_time;
+        long timeOnly = (m_time % MILLISECONDS_PER_DAY).GetLo();
+        timeMidnight -= timeOnly;
+
+        // TODO this probably could be optimised somehow...
+
+        double jdn = (timeMidnight / MILLISECONDS_PER_DAY).GetLo();
+        jdn += EPOCH_JDN + 0.5;
+        long z = jdn - 1721118.5;
+        double r = jdn - 1721118.5 - z;
+        double g = z - 0.25;
+        long a = g/36524.25;    // number of days per year
+        long b = a - a / 4;
+        int year = (b + g) / 365.25;
+        long c = b + z - 365.25*year;
+        int month = (5*c + 456)/153;
+        int day = c - (153*month - 457)/5 + (r < 0.5 ? 0 : 1);
+        if ( month > 12 )
+        {
+            year++;
+            month -= 12;
+        }
+
+        Tm tm;
+        tm.year = year;
+        tm.mon = (Month)(month - 1); // algorithm yields 1 for January, not 0
+        tm.mday = day;
+        tm.msec = timeOnly % 1000;
+        timeOnly -= tm.msec;
+        timeOnly /= 1000;               // now we have time in seconds
+
+        tm.sec = timeOnly % 60;
+        timeOnly -= tm.sec;
+        timeOnly /= 60;                 // now we have time in minutes
+
+        tm.min = timeOnly % 60;
+        timeOnly -= tm.min;
+
+        tm.hour = timeOnly / 60;
+
+        return tm;
+    }
+}
+
+wxDateTime& wxDateTime::SetYear(int year)
+{
+    wxASSERT_MSG( IsValid(), _T("invalid wxDateTime") );
+
+    Tm tm(GetTm());
+    tm.year = year;
+    Set(tm);
+
+    return *this;
+}
+
+wxDateTime& wxDateTime::SetMonth(Month month)
+{
+    wxASSERT_MSG( IsValid(), _T("invalid wxDateTime") );
+
+    Tm tm(GetTm());
+    tm.mon = month;
+    Set(tm);
+
+    return *this;
+}
+
+wxDateTime& wxDateTime::SetDay(wxDateTime_t mday)
+{
+    wxASSERT_MSG( IsValid(), _T("invalid wxDateTime") );
+
+    Tm tm(GetTm());
+    tm.mday = mday;
+    Set(tm);
+
+    return *this;
+}
+
+wxDateTime& wxDateTime::SetHour(wxDateTime_t hour)
+{
+    wxASSERT_MSG( IsValid(), _T("invalid wxDateTime") );
+
+    Tm tm(GetTm());
+    tm.hour = hour;
+    Set(tm);
+
+    return *this;
+}
+
+wxDateTime& wxDateTime::SetMinute(wxDateTime_t min)
+{
+    wxASSERT_MSG( IsValid(), _T("invalid wxDateTime") );
+
+    Tm tm(GetTm());
+    tm.min = min;
+    Set(tm);
+
+    return *this;
+}
+
+wxDateTime& wxDateTime::SetSecond(wxDateTime_t sec)
+{
+    wxASSERT_MSG( IsValid(), _T("invalid wxDateTime") );
+
+    Tm tm(GetTm());
+    tm.sec = sec;
+    Set(tm);
+
+    return *this;
+}
+
+wxDateTime& wxDateTime::SetMillisecond(wxDateTime_t millisecond)
+{
+    wxASSERT_MSG( IsValid(), _T("invalid wxDateTime") );
+
+    // we don't need to use GetTm() for this one
+    m_time -= m_time % 1000l;
+    m_time += millisecond;
+
+    return *this;
+}
+
+// ----------------------------------------------------------------------------
+// wxDateTime arithmetics
+// ----------------------------------------------------------------------------
+
+wxDateTime& wxDateTime::Add(const wxDateSpan& diff)
+{
+    Tm tm(GetTm());
+
+    tm.year += diff.GetYears();
+    tm.AddMonths(diff.GetMonths());
+    tm.AddDays(diff.GetTotalDays());
+
+    Set(tm);
+
+    return *this;
+}
+
+// ----------------------------------------------------------------------------
+// Weekday and monthday stuff
+// ----------------------------------------------------------------------------
+
+wxDateTime& wxDateTime::SetToLastMonthDay(Month month,
+                                          int year)
+{
+    // take the current month/year if none specified
+    ReplaceDefaultYearMonthWithCurrent(&year, &month);
+
+    return Set(GetNumOfDaysInMonth(year, month), month, year);
+}
+
+bool wxDateTime::SetToWeekDay(WeekDay weekday,
+                              int n,
+                              Month month,
+                              int year)
+{
+    wxCHECK_MSG( weekday != Inv_WeekDay, FALSE, _T("invalid weekday") );
+
+    // we don't check explicitly that -5 <= n <= 5 because we will return FALSE
+    // anyhow in such case - but may be should still give an assert for it?
+
+    // take the current month/year if none specified
+    ReplaceDefaultYearMonthWithCurrent(&year, &month);
+
+    wxDateTime dt;
+
+    // TODO this probably could be optimised somehow...
+
+    if ( n > 0 )
+    {
+        // get the first day of the month
+        dt.Set(1, month, year);
+
+        // get its wday
+        WeekDay wdayFirst = dt.GetWeekDay();
+
+        // go to the first weekday of the month
+        int diff = weekday - wdayFirst;
+        if ( diff < 0 )
+            diff += 7;
+
+        // add advance n-1 weeks more
+        diff += 7*(n - 1);
+
+        dt -= wxDateSpan::Days(diff);
+    }
+    else
+    {
+        // get the last day of the month
+        dt.SetToLastMonthDay(month, year);
+
+        // get its wday
+        WeekDay wdayLast = dt.GetWeekDay();
+
+        // go to the last weekday of the month
+        int diff = wdayLast - weekday;
+        if ( diff < 0 )
+            diff += 7;
+
+        // and rewind n-1 weeks from there
+        diff += 7*(n - 1);
+
+        dt -= wxDateSpan::Days(diff);
+    }
+
+    // check that it is still in the same month
+    if ( dt.GetMonth() == month )
+    {
+        *this = dt;
+
+        return TRUE;
+    }
+    else
+    {
+        // no such day in this month
+        return FALSE;
+    }
+}
+
+// ----------------------------------------------------------------------------
+// Julian day number conversion and related stuff
+// ----------------------------------------------------------------------------
+
+double wxDateTime::GetJulianDayNumber() const
+{
+    Tm tm(GetTm());
+
+    double result = GetTruncatedJDN(tm.mday, tm.mon, tm.year);
+
+    // add the part GetTruncatedJDN() neglected
+    result += 0.5;
+
+    // and now add the time: 86400 sec = 1 JDN
+    return result + ((double)(60*(60*tm.hour + tm.min) + tm.sec)) / 86400;
+}
+
+double wxDateTime::GetRataDie() const
+{
+    // March 1 of the year 0 is Rata Die day -306 and JDN 1721119.5
+    return GetJulianDayNumber() - 1721119.5 - 306;
+}
+
+// ----------------------------------------------------------------------------
+// timezone stuff
+// ----------------------------------------------------------------------------
+
+wxDateTime& wxDateTime::MakeUTC()
+{
+    return Add(wxTimeSpan::Seconds(GetTimeZone()));
+}
+
+wxDateTime& wxDateTime::MakeTimezone(const TimeZone& tz)
+{
+    int minDiff = GetTimeZone() / SECONDS_IN_MINUTE + tz.GetOffset();
+    return Add(wxTimeSpan::Minutes(minDiff));
+}
+
+wxDateTime& wxDateTime::MakeLocalTime(const TimeZone& tz)
+{
+    int minDiff = GetTimeZone() / SECONDS_IN_MINUTE + tz.GetOffset();
+    return Substract(wxTimeSpan::Minutes(minDiff));
+}
+
+// ----------------------------------------------------------------------------
+// wxDateTime to/from text representations
+// ----------------------------------------------------------------------------
+
+wxString wxDateTime::Format(const wxChar *format) const
+{
+    wxCHECK_MSG( format, _T(""), _T("NULL format in wxDateTime::Format") );
+
+    time_t time = GetTicks();
+    if ( time != (time_t)-1 )
+    {
+        // use strftime()
+        tm *tm = localtime(&time);
+
+        // should never happen
+        wxCHECK_MSG( tm, _T(""), _T("localtime() failed") );
+
+        return CallStrftime(format, tm);
+    }
+    else
+    {
+        // use a hack and still use strftime(): make a copy of the format and
+        // replace all occurences of YEAR in it with some unique string not
+        // appearing anywhere else in it, then use strftime() to format the
+        // date in year YEAR and then replace YEAR back by the real year and
+        // the unique replacement string back with YEAR where YEAR is any year
+        // in the range supported by strftime() (1970 - 2037) which is equal to
+        // the real year modulo 28 (so the week days coincide for them)
+
+        // find the YEAR
+        int yearReal = GetYear();
+        int year = 1970 + yearReal % 28;
+
+        wxString strYear;
+        strYear.Printf(_T("%d"), year);
+
+        // find a string not occuring in format (this is surely not optimal way
+        // of doing it... improvements welcome!)
+        wxString fmt = format;
+        wxString replacement = (wxChar)-1;
+        while ( fmt.Find(replacement) != wxNOT_FOUND )
+        {
+            replacement << (wxChar)-1;
+        }
+
+        // replace all occurences of year with it
+        bool wasReplaced = fmt.Replace(strYear, replacement) > 0;
+
+        // use strftime() to format the same date but in supported year
+        wxDateTime dt(*this);
+        dt.SetYear(year);
+        wxString str = dt.Format(format);
+
+        // now replace the occurence of 1999 with the real year
+        wxString strYearReal;
+        strYearReal.Printf(_T("%d"), yearReal);
+        str.Replace(strYear, strYearReal);
+
+        // and replace back all occurences of replacement string
+        if ( wasReplaced )
+            str.Replace(replacement, strYear);
+
+        return str;
+    }
+}
+
+// ============================================================================
+// wxTimeSpan
+// ============================================================================
+
+// not all strftime(3) format specifiers make sense here because, for example,
+// a time span doesn't have a year nor a timezone
+//
+// Here are the ones which are supported (all of them are supported by strftime
+// as well):
+//  %H          hour in 24 hour format
+//  %M          minute (00 - 59)
+//  %S          second (00 - 59)
+//  %%          percent sign
+//
+// Also, for MFC CTimeSpan compatibility, we support
+//  %D          number of days
+//
+// And, to be better than MFC :-), we also have
+//  %E          number of wEeks
+//  %l          milliseconds (000 - 999)
+wxString wxTimeSpan::Format(const wxChar *format) const
+{
+    wxCHECK_MSG( format, _T(""), _T("NULL format in wxTimeSpan::Format") );
+
+    wxString str;
+    str.Alloc(strlen(format));
+
+    for ( const wxChar *pch = format; pch; pch++ )
+    {
+        wxChar ch = *pch;
+
+        if ( ch == '%' )
+        {
+            wxString tmp;
+
+            ch = *pch++;
+            switch ( ch )
+            {
+                default:
+                    wxFAIL_MSG( _T("invalid format character") );
+                    // fall through
+
+                case '%':
+                    // will get to str << ch below
+                    break;
+
+                case 'D':
+                    tmp.Printf(_T("%d"), GetDays());
+                    break;
+
+                case 'E':
+                    tmp.Printf(_T("%d"), GetWeeks());
+                    break;
+
+                case 'H':
+                    tmp.Printf(_T("%02d"), GetHours());
+                    break;
+
+                case 'l':
+                    tmp.Printf(_T("%03d"), GetMilliseconds());
+                    break;
+
+                case 'M':
+                    tmp.Printf(_T("%02d"), GetMinutes());
+                    break;
+
+                case 'S':
+                    tmp.Printf(_T("%02d"), GetSeconds());
+                    break;
+            }
+
+            if ( !!tmp )
+            {
+                str += tmp;
+
+                // skip str += ch below
+                continue;
+            }
+        }
+
+        str += ch;
+    }
+
+    return str;
+}