* Implementation notes:
*
* 1. the time is stored as a 64bit integer containing the signed number of
- * milliseconds since Jan 1. 1970 (the Unix Epoch)
+ * milliseconds since Jan 1. 1970 (the Unix Epoch) - so it is always
+ * expressed in GMT.
*
* 2. the range is thus something about 580 million years, but due to current
* algorithms limitations, only dates from Nov 24, 4714BC are handled
* algorithm used by Scott E. Lee's code only works for positive JDNs, more
* or less)
*
+ * 5. the object constructed for the given DD-MM-YYYY HH:MM:SS corresponds to
+ * this moment in local time and may be converted to the object
+ * corresponding to the same date/time in another time zone by using
+ * ToTimezone()
+ *
+ * 6. the conversions to the current (or any other) timezone are done when the
+ * internal time representation is converted to the broken-down one in
+ * wxDateTime::Tm.
*/
// ============================================================================
#include "wx/datetime.h"
+#ifndef WX_TIMEZONE
+ #define WX_TIMEZONE timezone
+#endif
+
// ----------------------------------------------------------------------------
// constants
// ----------------------------------------------------------------------------
s_timezoneSet = TRUE;
}
- return (int)timezone;
+ return (int)WX_TIMEZONE;
}
// return the integral part of the JDN for the midnight of the given date (to
wday = wxDateTime::Inv_WeekDay;
}
-wxDateTime::Tm::Tm(const struct tm& tm)
+wxDateTime::Tm::Tm(const struct tm& tm, const TimeZone& tz)
+ : m_tz(tz)
{
msec = 0;
sec = tm.tm_sec;
{
// 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)) &&
+ (mday <= GetNumOfDaysInMonth(year, mon)) &&
(hour < 24) && (min < 60) && (sec < 62) && (msec < 1000);
}
void wxDateTime::Tm::ComputeWeekDay()
{
- wxFAIL_MSG(_T("TODO"));
+ // compute the week day from day/month/year: we use the dumbest algorithm
+ // possible: just compute our JDN and then use the (simple to derive)
+ // formula: weekday = (JDN + 1.5) % 7
+ wday = (wxDateTime::WeekDay)(GetTruncatedJDN(mday, mon, year) + 2) % 7;
}
void wxDateTime::Tm::AddMonths(int monDiff)
while ( monDiff + mon > MONTHS_IN_YEAR )
{
year++;
+
+ monDiff -= MONTHS_IN_YEAR;
}
mon = (wxDateTime::Month)(mon + monDiff);
switch ( tz )
{
case wxDateTime::Local:
- // leave offset to be 0
+ // get the offset from C RTL: it returns the difference GMT-local
+ // while we want to have the offset _from_ GMT, hence the '-'
+ m_offset = -GetTimeZone();
break;
case wxDateTime::GMT_12:
case wxDateTime::GMT_3:
case wxDateTime::GMT_2:
case wxDateTime::GMT_1:
- m_offset = -60*(wxDateTime::GMT0 - tz);
+ m_offset = -3600*(wxDateTime::GMT0 - tz);
break;
case wxDateTime::GMT0:
case wxDateTime::GMT10:
case wxDateTime::GMT11:
case wxDateTime::GMT12:
- m_offset = 60*(tz - wxDateTime::GMT0);
+ m_offset = 3600*(tz - wxDateTime::GMT0);
break;
case wxDateTime::A_CST:
// Central Standard Time in use in Australia = UTC + 9.5
- m_offset = 9*60 + 30;
+ m_offset = 60*(9*60 + 30);
break;
default:
return year > 0 ? year / 100 : year / 100 - 1;
}
-/* static */
-void wxDateTime::SetCountry(wxDateTime::Country country)
-{
- ms_country = country;
-}
-
/* static */
int wxDateTime::ConvertYearToBC(int year)
{
// and offset it by the number of days needed to get the correct wday
tm.tm_mday += wday;
+ // call mktime() to normalize it...
+ (void)mktime(&tm);
+
+ // ... and call strftime()
return CallStrftime(abbr ? _T("%a") : _T("%A"), &tm);
}
// ----------------------------------------------------------------------------
-// constructors and assignment operators
+// Country stuff: date calculations depend on the country (DST, work days,
+// ...), so we need to know which rules to follow.
// ----------------------------------------------------------------------------
-wxDateTime& wxDateTime::Set(const struct tm& tm1)
+/* static */
+wxDateTime::Country wxDateTime::GetCountry()
{
- wxASSERT_MSG( IsValid(), _T("invalid wxDateTime") );
+ if ( ms_country == Country_Unknown )
+ {
+ // try to guess from the time zone name
+ time_t t = time(NULL);
+ struct tm *tm = localtime(&t);
- tm tm2(tm1);
+ wxString tz = CallStrftime(_T("%Z"), tm);
+ if ( tz == _T("WET") || tz == _T("WEST") )
+ {
+ ms_country = UK;
+ }
+ else if ( tz == _T("CET") || tz == _T("CEST") )
+ {
+ ms_country = Country_EEC;
+ }
+ else if ( tz == _T("MSK") || tz == _T("MSD") )
+ {
+ ms_country = Russia;
+ }
+ else if ( tz == _T("AST") || tz == _T("ADT") ||
+ tz == _T("EST") || tz == _T("EDT") ||
+ tz == _T("CST") || tz == _T("CDT") ||
+ tz == _T("MST") || tz == _T("MDT") ||
+ tz == _T("PST") || tz == _T("PDT") )
+ {
+ ms_country = USA;
+ }
+ else
+ {
+ // well, choose a default one
+ ms_country = USA;
+ }
+ }
- // we want the time in GMT, mktime() takes the local time, so use timegm()
- // if it's available
-#ifdef HAVE_TIMEGM
- time_t timet = timegm(&tm2);
-#else // !HAVE_TIMEGM
- // FIXME this almost surely doesn't work
- tm2.tm_sec -= GetTimeZone();
+ return ms_country;
+}
- time_t timet = mktime(&tm2);
+/* static */
+void wxDateTime::SetCountry(wxDateTime::Country country)
+{
+ ms_country = country;
+}
+
+/* static */
+bool wxDateTime::IsWestEuropeanCountry(Country country)
+{
+ if ( country == Country_Default )
+ {
+ country = GetCountry();
+ }
+
+ return (Country_WesternEurope_Start <= country) &&
+ (country <= Country_WesternEurope_End);
+}
+
+// ----------------------------------------------------------------------------
+// DST calculations: we use 3 different rules for the West European countries,
+// USA and for the rest of the world. This is undoubtedly false for many
+// countries, but I lack the necessary info (and the time to gather it),
+// please add the other rules here!
+// ----------------------------------------------------------------------------
+
+/* static */
+bool wxDateTime::IsDSTApplicable(int year, Country country)
+{
+ if ( year == Inv_Year )
+ {
+ // take the current year if none given
+ year = GetCurrentYear();
+ }
+
+ if ( country == Country_Default )
+ {
+ country = GetCountry();
+ }
+
+ switch ( country )
+ {
+ case USA:
+ case UK:
+ // DST was first observed in the US and UK during WWI, reused
+ // during WWII and used again since 1966
+ return year >= 1966 ||
+ (year >= 1942 && year <= 1945) ||
+ (year == 1918 || year == 1919);
+
+ default:
+ // assume that it started after WWII
+ return year > 1950;
+ }
+}
+
+/* static */
+wxDateTime wxDateTime::GetBeginDST(int year, Country country)
+{
+ if ( year == Inv_Year )
+ {
+ // take the current year if none given
+ year = GetCurrentYear();
+ }
- if ( tm2.tm_isdst )
+ if ( country == Country_Default )
{
- tm2.tm_hour += 1;
+ country = GetCountry();
+ }
- timet = mktime(&tm2);
+ if ( !IsDSTApplicable(year, country) )
+ {
+ return ms_InvDateTime;
}
-#endif // HAVE_TIMEGM/!HAVE_TIMEGM
- if ( timet == (time_t)(-1) )
+ wxDateTime dt;
+
+ if ( IsWestEuropeanCountry(country) || (country == Russia) )
{
- wxFAIL_MSG(_T("Invalid time"));
+ // DST begins at 1 a.m. GMT on the last Sunday of March
+ if ( !dt.SetToLastWeekDay(Sun, Mar, year) )
+ {
+ // weird...
+ wxFAIL_MSG( _T("no last Sunday in March?") );
+ }
+
+ dt += wxTimeSpan::Hours(1);
+
+ dt.MakeGMT();
+ }
+ else switch ( country )
+ {
+ case USA:
+ switch ( year )
+ {
+ case 1918:
+ case 1919:
+ // don't know for sure - assume it was in effect all year
+
+ case 1943:
+ case 1944:
+ case 1945:
+ dt.Set(1, Jan, year);
+ break;
+
+ case 1942:
+ // DST was installed Feb 2, 1942 by the Congress
+ dt.Set(2, Feb, year);
+ break;
+
+ // Oil embargo changed the DST period in the US
+ case 1974:
+ dt.Set(6, Jan, 1974);
+ break;
+
+ case 1975:
+ dt.Set(23, Feb, 1975);
+ break;
+
+ default:
+ // before 1986, DST begun on the last Sunday of April, but
+ // in 1986 Reagan changed it to begin at 2 a.m. of the
+ // first Sunday in April
+ if ( year < 1986 )
+ {
+ if ( !dt.SetToLastWeekDay(Sun, Apr, year) )
+ {
+ // weird...
+ wxFAIL_MSG( _T("no first Sunday in April?") );
+ }
+ }
+ else
+ {
+ if ( !dt.SetToWeekDay(Sun, 1, Apr, year) )
+ {
+ // weird...
+ wxFAIL_MSG( _T("no first Sunday in April?") );
+ }
+ }
+
+ dt += wxTimeSpan::Hours(2);
+
+ // TODO what about timezone??
+ }
+
+ break;
+
+ default:
+ // assume Mar 30 as the start of the DST for the rest of the world
+ // - totally bogus, of course
+ dt.Set(30, Mar, year);
+ }
+
+ return dt;
+}
+
+/* static */
+wxDateTime wxDateTime::GetEndDST(int year, Country country)
+{
+ if ( year == Inv_Year )
+ {
+ // take the current year if none given
+ year = GetCurrentYear();
+ }
+
+ if ( country == Country_Default )
+ {
+ country = GetCountry();
+ }
+
+ if ( !IsDSTApplicable(year, country) )
+ {
+ return ms_InvDateTime;
+ }
+
+ wxDateTime dt;
+
+ if ( IsWestEuropeanCountry(country) || (country == Russia) )
+ {
+ // DST ends at 1 a.m. GMT on the last Sunday of October
+ if ( !dt.SetToLastWeekDay(Sun, Oct, year) )
+ {
+ // weirder and weirder...
+ wxFAIL_MSG( _T("no last Sunday in October?") );
+ }
+
+ dt += wxTimeSpan::Hours(1);
+
+ dt.MakeGMT();
+ }
+ else switch ( country )
+ {
+ case USA:
+ switch ( year )
+ {
+ case 1918:
+ case 1919:
+ // don't know for sure - assume it was in effect all year
+
+ case 1943:
+ case 1944:
+ dt.Set(31, Dec, year);
+ break;
+
+ case 1945:
+ // the time was reset after the end of the WWII
+ dt.Set(30, Sep, year);
+ break;
+
+ default:
+ // DST ends at 2 a.m. on the last Sunday of October
+ if ( !dt.SetToLastWeekDay(Sun, Oct, year) )
+ {
+ // weirder and weirder...
+ wxFAIL_MSG( _T("no last Sunday in October?") );
+ }
+
+ dt += wxTimeSpan::Hours(2);
+
+ // TODO what about timezone??
+ }
+ break;
+
+ default:
+ // assume October 26th as the end of the DST - totally bogus too
+ dt.Set(26, Oct, year);
+ }
+
+ return dt;
+}
+
+// ----------------------------------------------------------------------------
+// constructors and assignment operators
+// ----------------------------------------------------------------------------
+
+// the values in the tm structure contain the local time
+wxDateTime& wxDateTime::Set(const struct tm& tm)
+{
+ wxASSERT_MSG( IsValid(), _T("invalid wxDateTime") );
+
+ struct tm tm2(tm);
+ time_t timet = mktime(&tm2);
+
+ if ( timet == (time_t)-1 )
+ {
+ // mktime() rather unintuitively fails for Jan 1, 1970 if the hour is
+ // less than timezone - try to make it work for this case
+ if ( tm2.tm_year == 70 && tm2.tm_mon == 0 && tm2.tm_mday == 1 )
+ {
+ // add timezone to make sure that date is in range
+ tm2.tm_sec -= GetTimeZone();
+
+ timet = mktime(&tm2);
+ if ( timet != (time_t)-1 )
+ {
+ timet += GetTimeZone();
+
+ return Set(timet);
+ }
+ }
+
+ wxFAIL_MSG( _T("mktime() failed") );
return ms_InvDateTime;
}
// get the current date from system
time_t timet = GetTimeNow();
- struct tm *tm = gmtime(&timet);
+ struct tm *tm = localtime(&timet);
+
+ wxCHECK_MSG( tm, ms_InvDateTime, _T("localtime() failed") );
// adjust the time
tm->tm_hour = hour;
tm.tm_hour = hour;
tm.tm_min = minute;
tm.tm_sec = second;
- tm.tm_isdst = -1; // mktime() will guess it (wrongly, probably)
+ tm.tm_isdst = -1; // mktime() will guess it
(void)Set(tm);
m_time -= EPOCH_JDN;
m_time *= SECONDS_PER_DAY * TIME_T_FACTOR;
- Add(wxTimeSpan(hour, minute, second, millisec));
+ // JDN corresponds to GMT, we take localtime
+ Add(wxTimeSpan(hour, minute, second + GetTimeZone(), millisec));
}
return *this;
// time_t <-> broken down time conversions
// ----------------------------------------------------------------------------
-wxDateTime::Tm wxDateTime::GetTm() const
+wxDateTime::Tm wxDateTime::GetTm(const TimeZone& tz) const
{
wxASSERT_MSG( IsValid(), _T("invalid wxDateTime") );
if ( time != (time_t)-1 )
{
// use C RTL functions
- tm *tm = gmtime(&time);
-
- // should never happen
- wxCHECK_MSG( tm, Tm(), _T("gmtime() failed") );
+ tm *tm;
+ if ( tz.GetOffset() == -GetTimeZone() )
+ {
+ // we are working with local time
+ tm = localtime(&time);
- return Tm(*tm);
- }
- else
- {
- // remember the time and do the calculations with the date only - this
- // eliminates rounding errors of the floating point arithmetics
+ // should never happen
+ wxCHECK_MSG( tm, Tm(), _T("gmtime() failed") );
+ }
+ else
+ {
+ time += tz.GetOffset();
+ if ( time >= 0 )
+ {
+ tm = gmtime(&time);
- wxLongLong timeMidnight = m_time;
+ // should never happen
+ wxCHECK_MSG( tm, Tm(), _T("gmtime() failed") );
+ }
+ else
+ {
+ tm = (struct tm *)NULL;
+ }
+ }
- long timeOnly = (m_time % MILLISECONDS_PER_DAY).ToLong();
- if ( timeOnly < 0 )
+ if ( tm )
{
- timeOnly = MILLISECONDS_PER_DAY - timeOnly;
+ return Tm(*tm, tz);
}
+ //else: use generic code below
+ }
- timeMidnight -= timeOnly;
+ // remember the time and do the calculations with the date only - this
+ // eliminates rounding errors of the floating point arithmetics
- // calculate the Gregorian date from JDN for the midnight of our date:
- // this will yield day, month (in 1..12 range) and year
+ wxLongLong timeMidnight = m_time + tz.GetOffset() * 1000;
- // actually, this is the JDN for the noon of the previous day
- long jdn = (timeMidnight / MILLISECONDS_PER_DAY).ToLong() + EPOCH_JDN;
+ long timeOnly = (timeMidnight % MILLISECONDS_PER_DAY).ToLong();
- // CREDIT: code below is by Scott E. Lee (but bugs are mine)
+ // we want to always have positive time and timeMidnight to be really
+ // the midnight before it
+ if ( timeOnly < 0 )
+ {
+ timeOnly = MILLISECONDS_PER_DAY + timeOnly;
+ }
- wxASSERT_MSG( jdn > -2, _T("JDN out of range") );
+ timeMidnight -= timeOnly;
- // calculate the century
- int temp = (jdn + JDN_OFFSET) * 4 - 1;
- int century = temp / DAYS_PER_400_YEARS;
+ // calculate the Gregorian date from JDN for the midnight of our date:
+ // this will yield day, month (in 1..12 range) and year
- // then the year and day of year (1 <= dayOfYear <= 366)
- temp = ((temp % DAYS_PER_400_YEARS) / 4) * 4 + 3;
- int year = (century * 100) + (temp / DAYS_PER_4_YEARS);
- int dayOfYear = (temp % DAYS_PER_4_YEARS) / 4 + 1;
+ // actually, this is the JDN for the noon of the previous day
+ long jdn = (timeMidnight / MILLISECONDS_PER_DAY).ToLong() + EPOCH_JDN;
- // and finally the month and day of the month
- temp = dayOfYear * 5 - 3;
- int month = temp / DAYS_PER_5_MONTHS;
- int day = (temp % DAYS_PER_5_MONTHS) / 5 + 1;
+ // CREDIT: code below is by Scott E. Lee (but bugs are mine)
- // month is counted from March - convert to normal
- if ( month < 10 )
- {
- month += 3;
- }
- else
- {
- year += 1;
- month -= 9;
- }
+ wxASSERT_MSG( jdn > -2, _T("JDN out of range") );
+
+ // calculate the century
+ int temp = (jdn + JDN_OFFSET) * 4 - 1;
+ int century = temp / DAYS_PER_400_YEARS;
- // year is offset by 4800
- year -= 4800;
+ // then the year and day of year (1 <= dayOfYear <= 366)
+ temp = ((temp % DAYS_PER_400_YEARS) / 4) * 4 + 3;
+ int year = (century * 100) + (temp / DAYS_PER_4_YEARS);
+ int dayOfYear = (temp % DAYS_PER_4_YEARS) / 4 + 1;
- // check that the algorithm gave us something reasonable
- wxASSERT_MSG( (0 < month) && (month <= 12), _T("invalid month") );
- wxASSERT_MSG( (1 <= day) && (day < 32), _T("invalid day") );
- wxASSERT_MSG( (INT_MIN <= year) && (year <= INT_MAX),
- _T("year range overflow") );
+ // and finally the month and day of the month
+ temp = dayOfYear * 5 - 3;
+ int month = temp / DAYS_PER_5_MONTHS;
+ int day = (temp % DAYS_PER_5_MONTHS) / 5 + 1;
- // construct Tm from these values
- Tm tm;
- tm.year = (int)year;
- tm.mon = (Month)(month - 1); // algorithm yields 1 for January, not 0
- tm.mday = (wxDateTime_t)day;
- tm.msec = timeOnly % 1000;
- timeOnly -= tm.msec;
- timeOnly /= 1000; // now we have time in seconds
+ // month is counted from March - convert to normal
+ if ( month < 10 )
+ {
+ month += 3;
+ }
+ else
+ {
+ year += 1;
+ month -= 9;
+ }
- tm.sec = timeOnly % 60;
- timeOnly -= tm.sec;
- timeOnly /= 60; // now we have time in minutes
+ // year is offset by 4800
+ year -= 4800;
- tm.min = timeOnly % 60;
- timeOnly -= tm.min;
+ // check that the algorithm gave us something reasonable
+ wxASSERT_MSG( (0 < month) && (month <= 12), _T("invalid month") );
+ wxASSERT_MSG( (1 <= day) && (day < 32), _T("invalid day") );
+ wxASSERT_MSG( (INT_MIN <= year) && (year <= INT_MAX),
+ _T("year range overflow") );
- tm.hour = timeOnly / 60;
+ // construct Tm from these values
+ Tm tm;
+ tm.year = (int)year;
+ tm.mon = (Month)(month - 1); // algorithm yields 1 for January, not 0
+ tm.mday = (wxDateTime_t)day;
+ tm.msec = timeOnly % 1000;
+ timeOnly -= tm.msec;
+ timeOnly /= 1000; // now we have time in seconds
- return tm;
- }
+ 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)
// add advance n-1 weeks more
diff += 7*(n - 1);
- dt -= wxDateSpan::Days(diff);
+ dt += wxDateSpan::Days(diff);
}
- else
+ else // count from the end of the month
{
// get the last day of the month
dt.SetToLastMonthDay(month, year);
diff += 7;
// and rewind n-1 weeks from there
- diff += 7*(n - 1);
+ diff += 7*(-n - 1);
dt -= wxDateSpan::Days(diff);
}
}
}
+wxDateTime::wxDateTime_t wxDateTime::GetDayOfYear(const TimeZone& tz) const
+{
+ // this array contains the cumulated number of days in all previous months
+ // for normal and leap years
+ static const wxDateTime_t cumulatedDays[2][MONTHS_IN_YEAR] =
+ {
+ { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 },
+ { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335 }
+ };
+
+ Tm tm(GetTm(tz));
+
+ return cumulatedDays[IsLeapYear(tm.year)][tm.mon] + tm.mday;
+}
+
+wxDateTime::wxDateTime_t wxDateTime::GetWeekOfYear(const TimeZone& tz) const
+{
+ // the first week of the year is the one which contains Jan, 4 (according
+ // to ISO standard rule), so the year day N0 = 4 + 7*W always lies in the
+ // week W+1. As any day N = 7*W + 4 + (N - 4)%7, it lies in the same week
+ // as N0 or in the next one.
+
+ // TODO this surely may be optimized - I got confused while writing it
+
+ wxDateTime_t nDayInYear = GetDayOfYear(tz);
+
+ // the week day of the day lying in the first week
+ WeekDay wdayStart = wxDateTime(4, Jan, GetYear()).GetWeekDay();
+
+ wxDateTime_t week = (nDayInYear - 4) / 7 + 1;
+
+ // notice that Sunday shoould be counted as 7, not 0 here!
+ if ( ((nDayInYear - 4) % 7) + (!wdayStart ? 7 : wdayStart) > 7 )
+ {
+ week++;
+ }
+
+ return week;
+}
+
// ----------------------------------------------------------------------------
// Julian day number conversion and related stuff
// ----------------------------------------------------------------------------
double wxDateTime::GetJulianDayNumber() const
{
- Tm tm(GetTm());
+ // JDN are always expressed for the GMT dates
+ Tm tm(ToTimezone(GMT0).GetTm(GMT0));
double result = GetTruncatedJDN(tm.mday, tm.mon, tm.year);
}
// ----------------------------------------------------------------------------
-// timezone stuff
+// timezone and DST stuff
// ----------------------------------------------------------------------------
-wxDateTime& wxDateTime::MakeUTC()
+int wxDateTime::IsDST(wxDateTime::Country country) const
{
- return Add(wxTimeSpan::Seconds(GetTimeZone()));
+ wxCHECK_MSG( country == Country_Default, -1,
+ _T("country support not implemented") );
+
+ // use the C RTL for the dates in the standard range
+ time_t timet = GetTicks();
+ if ( timet != (time_t)-1 )
+ {
+ tm *tm = localtime(&timet);
+
+ wxCHECK_MSG( tm, -1, _T("localtime() failed") );
+
+ return tm->tm_isdst;
+ }
+ else
+ {
+ int year = GetYear();
+
+ if ( !IsDSTApplicable(year, country) )
+ {
+ // no DST time in this year in this country
+ return -1;
+ }
+
+ return IsBetween(GetBeginDST(year, country), GetEndDST(year, country));
+ }
}
wxDateTime& wxDateTime::MakeTimezone(const TimeZone& tz)
{
- int minDiff = GetTimeZone() / SECONDS_IN_MINUTE + tz.GetOffset();
- return Add(wxTimeSpan::Minutes(minDiff));
-}
+ int secDiff = GetTimeZone() + tz.GetOffset();
-wxDateTime& wxDateTime::MakeLocalTime(const TimeZone& tz)
-{
- int minDiff = GetTimeZone() / SECONDS_IN_MINUTE + tz.GetOffset();
- return Substract(wxTimeSpan::Minutes(minDiff));
+ // we need to know whether DST is or not in effect for this date
+ if ( IsDST() == 1 )
+ {
+ // FIXME we assume that the DST is always shifted by 1 hour
+ secDiff -= 3600;
+ }
+
+ return Substract(wxTimeSpan::Seconds(secDiff));
}
// ----------------------------------------------------------------------------
// wxDateTime to/from text representations
// ----------------------------------------------------------------------------
-wxString wxDateTime::Format(const wxChar *format) const
+wxString wxDateTime::Format(const wxChar *format, const TimeZone& tz) const
{
wxCHECK_MSG( format, _T(""), _T("NULL format in wxDateTime::Format") );
if ( time != (time_t)-1 )
{
// use strftime()
- tm *tm = gmtime(&time);
+ tm *tm;
+ if ( tz.GetOffset() == -GetTimeZone() )
+ {
+ // we are working with local time
+ tm = localtime(&time);
- // should never happen
- wxCHECK_MSG( tm, _T(""), _T("gmtime() failed") );
+ // should never happen
+ wxCHECK_MSG( tm, wxEmptyString, _T("localtime() failed") );
+ }
+ else
+ {
+ time += tz.GetOffset();
- 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 )
+ if ( time >= 0 )
+ {
+ tm = gmtime(&time);
+
+ // should never happen
+ wxCHECK_MSG( tm, wxEmptyString, _T("gmtime() failed") );
+ }
+ else
+ {
+ tm = (struct tm *)NULL;
+ }
+ }
+
+ if ( tm )
{
- replacement << (wxChar)-1;
+ return CallStrftime(format, tm);
}
+ //else: use generic code below
+ }
+
+ // use a hack and still use strftime(): first find the YEAR which is a year
+ // in the strftime() range (1970 - 2038) whose Jan 1 falls on the same week
+ // day as the Jan 1 of the real year. Then 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. Notice that "all occurences of YEAR"
+ // means all occurences of 4 digit as well as 2 digit form!
+
+ // NB: may be it would be simpler to "honestly" reimplement strftime()?
+
+ // find the YEAR: normally, for any year X, Jan 1 or the year X + 28 is the
+ // same weekday as Jan 1 of X (because the weekday advances by 1 for each
+ // normal X and by 2 for each leap X, hence by 5 every 4 years or by 35
+ // which is 0 mod 7 every 28 years) but this rule breaks down if there are
+ // years between X and Y which are divisible by 4 but not leap (i.e.
+ // divisible by 100 but not 400), hence the correction.
+
+ int yearReal = GetYear(tz);
+ int year = 1970 + yearReal % 28;
+
+ int nCenturiesInBetween = (year / 100) - (yearReal / 100);
+ int nLostWeekDays = nCenturiesInBetween - (nCenturiesInBetween / 400);
+
+ // we have to gain back the "lost" weekdays...
+ while ( (nLostWeekDays % 7) != 0 )
+ {
+ nLostWeekDays += year++ % 4 ? 1 : 2;
+ }
- // replace all occurences of year with it
- bool wasReplaced = fmt.Replace(strYear, replacement) > 0;
+ // at any rate, we can't go further than 1997 + 28!
+ wxASSERT_MSG( year < 2030, _T("logic error in wxDateTime::Format") );
- // use strftime() to format the same date but in supported year
- wxDateTime dt(*this);
- dt.SetYear(year);
- wxString str = dt.Format(format);
+ wxString strYear, strYear2;
+ strYear.Printf(_T("%d"), year);
+ strYear2.Printf(_T("%d"), year % 100);
- // now replace the occurence of 1999 with the real year
- wxString strYearReal;
- strYearReal.Printf(_T("%d"), yearReal);
- str.Replace(strYear, strYearReal);
+ // find two strings 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;
+ }
- // and replace back all occurences of replacement string
- if ( wasReplaced )
- str.Replace(replacement, strYear);
+ wxString replacement2 = (wxChar)-2;
+ while ( fmt.Find(replacement) != wxNOT_FOUND )
+ {
+ replacement << (wxChar)-2;
+ }
- return str;
+ // replace all occurences of year with it
+ bool wasReplaced = fmt.Replace(strYear, replacement) > 0;
+ if ( !wasReplaced )
+ wasReplaced = fmt.Replace(strYear2, replacement2) > 0;
+
+ // use strftime() to format the same date but in supported year
+ wxDateTime dt(*this);
+ dt.SetYear(year);
+ wxString str = dt.Format(format, tz);
+
+ // now replace the occurence of 1999 with the real year
+ wxString strYearReal, strYearReal2;
+ strYearReal.Printf(_T("%04d"), yearReal);
+ strYearReal2.Printf(_T("%02d"), yearReal % 100);
+ str.Replace(strYear, strYearReal);
+ str.Replace(strYear2, strYearReal2);
+
+ // and replace back all occurences of replacement string
+ if ( wasReplaced )
+ {
+ str.Replace(replacement2, strYear2);
+ str.Replace(replacement, strYear);
}
+
+ return str;
}
// ============================================================================
break;
case 'l':
- tmp.Printf(_T("%03d"), GetMilliseconds());
+ tmp.Printf(_T("%03d"), GetMilliseconds().GetValue());
break;
case 'M':
break;
case 'S':
- tmp.Printf(_T("%02d"), GetSeconds());
+ tmp.Printf(_T("%02d"), GetSeconds().GetValue());
break;
}
projects / wxWidgets.git / blobdiff