datetime.cpp

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//
// DateTime.cpp
//
// $Id: //poco/Main/Foundation/src/DateTime.cpp#5 $
//
// Copyright (c) 2004, Guenter Obiltschnig/Applied Informatics.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
//
// 3. Redistributions in any form must be accompanied by information on
//    how to obtain complete source code for this software and any
//    accompanying software that uses this software.  The source code
//    must either be included in the distribution or be available for no
//    more than the cost of distribution plus a nominal fee, and must be
//    freely redistributable under reasonable conditions.  For an
//    executable file, complete source code means the source code for all
//    modules it contains.  It does not include source code for modules or
//    files that typically accompany the major components of the operating
//    system on which the executable file runs.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
// ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//


#include "Foundation/DateTime.h"
#include <math.h>


Foundation_BEGIN


inline double DateTime::toJulianDay(Timestamp::UtcTimeVal utcTime)
{
	double utcDays = double(utcTime)/864000000000.0;
	return utcDays + 2299160.5; // first day of Gregorian reform (Oct 15 1582)
}


inline Timestamp::UtcTimeVal DateTime::toUtcTime(double julianDay)
{
	return Timestamp::UtcTimeVal((julianDay - 2299160.5)*864000000000.0);
}


DateTime::DateTime()
{
	Timestamp now;
	_utcTime = now.utcTime();
	_julianDay = toJulianDay(_utcTime);
	computeGregorian();
}


DateTime::DateTime(const Timestamp& timestamp):
	_utcTime(timestamp.utcTime()),
	_julianDay(toJulianDay(_utcTime))
{
	computeGregorian();
}

	
DateTime::DateTime(int year, int month, int day, int hour, int minute, int second, int millisecond, int microsecond):
	_year(year),
	_month(month),
	_day(day),
	_hour(hour),
	_minute(minute),
	_second(second),
	_millisecond(millisecond),
	_microsecond(microsecond)
{
	poco_assert (year >= 0 && year <= 9999);
	poco_assert (month >= 1 && month <= 12);
	poco_assert (day >= 1 && day <= daysOfMonth(year, month));
	poco_assert (hour >= 0 && hour <= 23);
	poco_assert (minute >= 0 && minute <= 59);
	poco_assert (second >= 0 && second <= 59);
	poco_assert (millisecond >= 0 && millisecond <= 999);
	poco_assert (microsecond >= 0 && millisecond <= 999);
	
	_julianDay = toJulianDay(year, month, day, hour, minute, second, millisecond, microsecond);
	_utcTime   = toUtcTime(_julianDay);
}


DateTime::DateTime(double julianDay):
	_utcTime(toUtcTime(julianDay)),
	_julianDay(julianDay)
{
	computeGregorian();
}


DateTime::DateTime(const DateTime& dateTime):
	_utcTime(dateTime._utcTime),
	_julianDay(dateTime._julianDay),
	_year(dateTime._year),
	_month(dateTime._month),
	_day(dateTime._day),
	_hour(dateTime._hour),
	_minute(dateTime._minute),
	_second(dateTime._second),
	_millisecond(dateTime._millisecond),
	_microsecond(dateTime._microsecond)
{
}


DateTime::~DateTime()
{
}


DateTime& DateTime::operator = (const DateTime& dateTime)
{
	if (&dateTime != this)
	{
		_utcTime     = dateTime._utcTime;
		_julianDay   = dateTime._julianDay;
		_year        = dateTime._year;
		_month       = dateTime._month;
		_day         = dateTime._day;
		_hour        = dateTime._hour;
		_minute      = dateTime._minute;
		_second      = dateTime._second;
		_millisecond = dateTime._millisecond;
		_microsecond = dateTime._microsecond;
	}
	return *this;
}

	
DateTime& DateTime::operator = (const Timestamp& timestamp)
{
	_utcTime   = timestamp.utcTime();
	_julianDay = toJulianDay(_utcTime);
	computeGregorian();
	return *this;
}


DateTime& DateTime::operator = (double julianDay)
{
	_julianDay = julianDay;
	_utcTime   = toUtcTime(julianDay);
	computeGregorian();
	return *this;
}


DateTime& DateTime::assign(int year, int month, int day, int hour, int minute, int second, int millisecond, int microsecond)
{
	poco_assert (year >= 0 && year <= 9999);
	poco_assert (month >= 1 && month <= 12);
	poco_assert (day >= 1 && day <= daysOfMonth(year, month));
	poco_assert (hour >= 0 && hour <= 23);
	poco_assert (minute >= 0 && minute <= 59);
	poco_assert (second >= 0 && second <= 59);
	poco_assert (millisecond >= 0 && millisecond <= 999);
	poco_assert (microsecond >= 0 && millisecond <= 999);

	_julianDay   = toJulianDay(year, month, day, hour, minute, second, millisecond, microsecond);
	_utcTime     = toUtcTime(_julianDay);
	_year        = year;
	_month       = month;
	_day         = day;
	_hour        = hour;
	_minute      = minute;
	_second      = second;
	_millisecond = millisecond;
	
	return *this;
}


int DateTime::dayOfWeek() const
{
	return int((floor(_julianDay + 1.5))) % 7;
}


int DateTime::dayOfYear() const
{
	int doy = 0;
	for (int month = 1; month < _month; ++month)
		doy += daysOfMonth(_year, month);
	doy += _day;
	return doy;
}


int DateTime::daysOfMonth(int year, int month)
{
	poco_assert (month >= 1 && month <= 12);

	static int daysOfMonthTable[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
	
	if (month == 2 && isLeapYear(year))
		return 29;
	else
		return daysOfMonthTable[month];
}


int DateTime::week(int firstDayOfWeek) const
{
	poco_assert (firstDayOfWeek >= 0 && firstDayOfWeek <= 6);

	/// find the first firstDayOfWeek.
	int baseDay = 1;
	while (DateTime(_year, 1, baseDay).dayOfWeek() != firstDayOfWeek) ++baseDay;

	int doy  = dayOfYear();
	int offs = baseDay <= 4 ? 0 : 1; 
	if (doy < baseDay)
		return offs;
	else
		return (doy - baseDay)/7 + 1 + offs;
}


double DateTime::toJulianDay(int year, int month, int day, int hour, int minute, int second, int millisecond, int microsecond)
{
	// lookup table for (153*month - 457)/5 - note that 3 <= month <= 14.
	static int lookup[] = {-91, -60, -30, 0, 31, 61, 92, 122, 153, 184, 214, 245, 275, 306, 337};
 
	// day to double
	double dday = double(day) + ((double((hour*60 + minute)*60 + second)*1000 + millisecond)*1000 + microsecond)/86400000000.0;
	if (month < 3)
	{
		month += 12;
		--year;
	}
	double dyear = double(year);
	return dday + lookup[month] + 365*year + floor(dyear/4) - floor(dyear/100) + floor(dyear/400) + 1721118.5;
}


void DateTime::computeGregorian()
{
	double z    = floor(_julianDay - 1721118.5);
	double r    = _julianDay - 1721118.5 - z;
	double g    = z - 0.25;
	double a    = floor(g / 36524.25);
	double b    = a - floor(a/4);
	_year       = short(floor((b + g)/365.25));
	double c    = b + z - floor(365.25*_year);
	_month      = short(floor((5*c + 456)/153));
	double dday = c - floor((153.0*_month - 457)/5) + r;
	_day        = short(dday);
	if (_month > 12)
	{
		++_year;
		_month -= 12;
	}
	r      *= 24;
	_hour   = short(floor(r));
	r      -= floor(r);
	r      *= 60;
	_minute = short(floor(r));
	r      -= floor(r);
	r      *= 60;
	_second = short(floor(r));
	r      -= floor(r);
	r      *= 1000;
	_millisecond = short(r + 0.5);
}


Foundation_END