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DateTime.h
//
// DateTime.h
//
// $Id: //poco/1.4/Foundation/include/Poco/DateTime.h#1 $
//
// Library: Foundation
// Package: DateTime
// Module:  DateTime
//
// Definition of the DateTime class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
// 
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//


#ifndef Foundation_DateTime_INCLUDED
#define Foundation_DateTime_INCLUDED


#include "Poco/Foundation.h"
#include "Poco/Timestamp.h"
#include "Poco/Timespan.h"


namespace Poco {


00051 class Foundation_API DateTime
      /// This class represents an instant in time, expressed
      /// in years, months, days, hours, minutes, seconds
      /// and milliseconds based on the Gregorian calendar.
      /// The class is mainly useful for conversions between
      /// UTC, Julian day and Gregorian calendar dates.
      ///
      /// The date and time stored in a DateTime is always in UTC
      /// (Coordinated Universal Time) and thus independent of the 
      /// timezone in effect on the system.
      ///
      /// Conversion calculations are based on algorithms
      /// collected and described by Peter Baum at
      /// http://vsg.cape.com/~pbaum/date/date0.htm
      ///
      /// Internally, this class stores a date/time in two
      /// forms (UTC and broken down) for performance reasons. Only use 
      /// this class for conversions between date/time representations.
      /// Use the Timestamp class for everything else.
      ///
      /// Notes:
      ///   * Zero is a valid year (in accordance with ISO 8601 and astronomical year numbering)
      ///   * Year zero (0) is a leap year
      ///   * Negative years (years preceding 1 BC) are not supported
      ///
      /// For more information, please see:
      ///   * http://en.wikipedia.org/wiki/Gregorian_Calendar
      ///   * http://en.wikipedia.org/wiki/Julian_day
      ///   * http://en.wikipedia.org/wiki/UTC
      ///   * http://en.wikipedia.org/wiki/ISO_8601
{
public:
00083       enum Months
            /// Symbolic names for month numbers (1 to 12).
      {
            JANUARY = 1,
            FEBRUARY,
            MARCH,
            APRIL,
            MAY,
            JUNE,
            JULY,
            AUGUST,
            SEPTEMBER,
            OCTOBER,
            NOVEMBER,
            DECEMBER
      };
      
00100       enum DaysOfWeek
            /// Symbolic names for week day numbers (0 to 6).
      {
            SUNDAY = 0,
            MONDAY,
            TUESDAY,
            WEDNESDAY,
            THURSDAY,
            FRIDAY,
            SATURDAY
      };
            
      DateTime();
            /// Creates a DateTime for the current date and time.

      DateTime(const Timestamp& timestamp);
            /// Creates a DateTime for the date and time given in
            /// a Timestamp.
            
      DateTime(int year, int month, int day, int hour = 0, int minute = 0, int second = 0, int millisecond = 0, int microsecond = 0);
            /// Creates a DateTime for the given Gregorian date and time.
            ///   * year is from 0 to 9999.
            ///   * month is from 1 to 12.
            ///   * day is from 1 to 31.
            ///   * hour is from 0 to 23.
            ///   * minute is from 0 to 59.
            ///   * second is from 0 to 59.
            ///   * millisecond is from 0 to 999.
            ///   * microsecond is from 0 to 999.

      DateTime(double julianDay);
            /// Creates a DateTime for the given Julian day.

      DateTime(Timestamp::UtcTimeVal utcTime, Timestamp::TimeDiff diff);
            /// Creates a DateTime from an UtcTimeVal and a TimeDiff.
            ///
            /// Mainly used internally by DateTime and friends.

      DateTime(const DateTime& dateTime);
            /// Copy constructor. Creates the DateTime from another one.

      ~DateTime();
            /// Destroys the DateTime.

      DateTime& operator = (const DateTime& dateTime);
            /// Assigns another DateTime.
            
      DateTime& operator = (const Timestamp& timestamp);
            /// Assigns a Timestamp.

      DateTime& operator = (double julianDay);
            /// Assigns a Julian day.

      DateTime& assign(int year, int month, int day, int hour = 0, int minute = 0, int second = 0, int millisecond = 0, int microseconds = 0);
            /// Assigns a Gregorian date and time.
            ///   * year is from 0 to 9999.
            ///   * month is from 1 to 12.
            ///   * day is from 1 to 31.
            ///   * hour is from 0 to 23.
            ///   * minute is from 0 to 59.
            ///   * second is from 0 to 59.
            ///   * millisecond is from 0 to 999.
            ///   * microsecond is from 0 to 999.

      void swap(DateTime& dateTime);
            /// Swaps the DateTime with another one.

      int year() const;
            /// Returns the year.
            
      int month() const;
            /// Returns the month (1 to 12).
      
      int week(int firstDayOfWeek = MONDAY) const;
            /// Returns the week number within the year.
            /// FirstDayOfWeek should be either SUNDAY (0) or MONDAY (1).
            /// The returned week number will be from 0 to 53. Week number 1 is the week 
            /// containing January 4. This is in accordance to ISO 8601.
            /// 
            /// The following example assumes that firstDayOfWeek is MONDAY. For 2005, which started
            /// on a Saturday, week 1 will be the week starting on Monday, January 3.
            /// January 1 and 2 will fall within week 0 (or the last week of the previous year).
            ///
            /// For 2007, which starts on a Monday, week 1 will be the week startung on Monday, January 1.
            /// There will be no week 0 in 2007.
      
      int day() const;
            /// Returns the day witin the month (1 to 31).
            
      int dayOfWeek() const;
            /// Returns the weekday (0 to 6, where
            /// 0 = Sunday, 1 = Monday, ..., 6 = Saturday).
      
      int dayOfYear() const;
            /// Returns the number of the day in the year.
            /// January 1 is 1, February 1 is 32, etc.
      
      int hour() const;
            /// Returns the hour (0 to 23).
            
      int hourAMPM() const;
            /// Returns the hour (0 to 12).
      
      bool isAM() const;
            /// Returns true if hour < 12;

      bool isPM() const;
            /// Returns true if hour >= 12.
            
      int minute() const;
            /// Returns the minute (0 to 59).
            
      int second() const;
            /// Returns the second (0 to 59).
            
      int millisecond() const;
            /// Returns the millisecond (0 to 999)
      
      int microsecond() const;
            /// Returns the microsecond (0 to 999)
      
      double julianDay() const;
            /// Returns the julian day for the date and time.
            
      Timestamp timestamp() const;
            /// Returns the date and time expressed as a Timestamp.

      Timestamp::UtcTimeVal utcTime() const;
            /// Returns the date and time expressed in UTC-based
            /// time. UTC base time is midnight, October 15, 1582.
            /// Resolution is 100 nanoseconds.
            
      bool operator == (const DateTime& dateTime) const;    
      bool operator != (const DateTime& dateTime) const;    
      bool operator <  (const DateTime& dateTime) const;    
      bool operator <= (const DateTime& dateTime) const;    
      bool operator >  (const DateTime& dateTime) const;    
      bool operator >= (const DateTime& dateTime) const;    

      DateTime  operator +  (const Timespan& span) const;
      DateTime  operator -  (const Timespan& span) const;
      Timespan  operator -  (const DateTime& dateTime) const;
      DateTime& operator += (const Timespan& span);
      DateTime& operator -= (const Timespan& span);
      
      void makeUTC(int tzd);
            /// Converts a local time into UTC, by applying the given time zone differential.
            
      void makeLocal(int tzd);
            /// Converts a UTC time into a local time, by applying the given time zone differential.
      
      static bool isLeapYear(int year);
            /// Returns true if the given year is a leap year;
            /// false otherwise.
            
      static int daysOfMonth(int year, int month);
            /// Returns the number of days in the given month
            /// and year. Month is from 1 to 12.
            
      static bool isValid(int year, int month, int day, int hour = 0, int minute = 0, int second = 0, int millisecond = 0, int microsecond = 0);
            /// Checks if the given date and time is valid
            /// (all arguments are within a proper range).
            ///
            /// Returns true if all arguments are valid, false otherwise.
            
protected:  
      static double toJulianDay(Timestamp::UtcTimeVal utcTime);
            /// Computes the Julian day for an UTC time.
      
      static double toJulianDay(int year, int month, int day, int hour = 0, int minute = 0, int second = 0, int millisecond = 0, int microsecond = 0);
            /// Computes the Julian day for a gregorian calendar date and time.
            /// See <http://vsg.cape.com/~pbaum/date/jdimp.htm>, section 2.3.1 for the algorithm.
      
      static Timestamp::UtcTimeVal toUtcTime(double julianDay);
            /// Computes the UTC time for a Julian day.
            
      void computeGregorian(double julianDay);
            /// Computes the Gregorian date for the given Julian day.
            /// See <http://vsg.cape.com/~pbaum/date/injdimp.htm>, section 3.3.1 for the algorithm.

      void computeDaytime();
            /// Extracts the daytime (hours, minutes, seconds, etc.) from the stored utcTime.

private:
      void checkLimit(short& lower, short& higher, short limit);
      void normalize();
            ///utility functions used to correct the overflow in computeGregorian

00288       Timestamp::UtcTimeVal _utcTime;
      short  _year;
      short  _month;
      short  _day;
      short  _hour;
      short  _minute;
      short  _second;
      short  _millisecond;
      short  _microsecond;
};


//
// inlines
//
00303 inline Timestamp DateTime::timestamp() const
{
      return Timestamp::fromUtcTime(_utcTime);
}


00309 inline Timestamp::UtcTimeVal DateTime::utcTime() const
{
      return _utcTime;
}


00315 inline int DateTime::year() const
{
      return _year;
}

      
00321 inline int DateTime::month() const
{
      return _month;
}

      
00327 inline int DateTime::day() const
{
      return _day;
}

      
00333 inline int DateTime::hour() const
{
      return _hour;
}


00339 inline int DateTime::hourAMPM() const
{
      if (_hour < 1)
            return 12;
      else if (_hour > 12)
            return _hour - 12;
      else
            return _hour;
}


00350 inline bool DateTime::isAM() const
{
      return _hour < 12;
}


00356 inline bool DateTime::isPM() const
{
      return _hour >= 12;
}

      
00362 inline int DateTime::minute() const
{
      return _minute;
}

      
00368 inline int DateTime::second() const
{
      return _second;
}

      
00374 inline int DateTime::millisecond() const
{
      return _millisecond;
}


00380 inline int DateTime::microsecond() const
{
      return _microsecond;
}


00386 inline bool DateTime::operator == (const DateTime& dateTime) const
{
      return _utcTime == dateTime._utcTime;
}


inline bool DateTime::operator != (const DateTime& dateTime) const      
{
      return _utcTime != dateTime._utcTime;
}


inline bool DateTime::operator <  (const DateTime& dateTime) const      
{
      return _utcTime < dateTime._utcTime;
}


inline bool DateTime::operator <= (const DateTime& dateTime) const
{
      return _utcTime <= dateTime._utcTime;
}


inline bool DateTime::operator >  (const DateTime& dateTime) const
{
      return _utcTime > dateTime._utcTime;
}


inline bool DateTime::operator >= (const DateTime& dateTime) const      
{
      return _utcTime >= dateTime._utcTime;
}


00422 inline bool DateTime::isLeapYear(int year)
{
      return (year % 4) == 0 && ((year % 100) != 0 || (year % 400) == 0);
}


inline void swap(DateTime& d1, DateTime& d2)
{
      d1.swap(d2);
}


} // namespace Poco


#endif // Foundation_DateTime_INCLUDED

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