OW_DateTime.cpp

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* modification, are permitted provided that the following conditions are met:
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#include "OW_config.h"
#include "OW_DateTime.hpp"
#include "OW_String.hpp"
#include "OW_BinarySerialization.hpp"
#include "OW_Format.hpp"
#include "OW_Mutex.hpp"
#include "OW_MutexLock.hpp"
#include "OW_ExceptionIds.hpp"

#if defined(OW_HAVE_ISTREAM) && defined(OW_HAVE_OSTREAM)
#include <istream>
#include <ostream>
#else
#include <iostream>
#endif

#include <time.h>
#ifdef OW_HAVE_SYS_TIME_H
#include <sys/time.h>
#endif

#include <cctype>


#ifndef OW_HAVE_LOCALTIME_R
namespace
{
   OW_NAMESPACE::Mutex localtimeMutex;
}
struct tm *localtime_r(const time_t *timep, struct tm *result)
{
   OW_NAMESPACE::MutexLock lock(localtimeMutex);
   struct tm *p = localtime(timep);
   
   if (p)
   {
      *(result) = *p;
   }
   
   return p;
}
#endif

#ifndef OW_HAVE_GMTIME_R
namespace
{
   OW_NAMESPACE::Mutex gmtimeMutex;
}
struct tm *gmtime_r(const time_t *timep, struct tm *result)
{
   OW_NAMESPACE::MutexLock lock(gmtimeMutex);
   struct tm *p = gmtime(timep);
   
   if (p)
   {
      *(result) = *p;
   }
   
   return p;
}
#endif

#ifndef OW_HAVE_ASCTIME_R
namespace
{
   OW_NAMESPACE::Mutex asctimeMutex;
}
char *asctime_r(const struct tm *tm, char *result)
{
   OW_NAMESPACE::MutexLock lock(asctimeMutex);
   char *p = asctime(tm);
   
   if (p)
   {
      //asctime_r requires a buffer to be at least 26 chars in size
      ::strncpy(result,p,25);
      result[25] = 0;
   }
   
   return result;
}
#endif

namespace OW_NAMESPACE
{

using std::istream;
using std::ostream;

OW_DEFINE_EXCEPTION_WITH_ID(DateTime);

DateTime::DateTime()
   : m_time(0)
   , m_microseconds(0)

{
}
namespace
{

inline void badDateTime(const String& str)
{
   OW_THROW(DateTimeException, Format("Invalid DateTime: %1", str).c_str());
}

inline void validateRanges(Int32 year, Int32 month, Int32 day, Int32 hour,
Int32 minute, Int32 second, Int32 microseconds, const String& str)
{
   if (year < 0 || year > 9999 ||
   month < 1 || month > 12 ||
   day < 1 || day > 31 ||
   hour < 0 || hour > 23 ||
   minute < 0 || minute > 59 ||
   second < 0 || second > 60 ||
   microseconds < 0 || microseconds > 999999)
   {
      badDateTime(str);
   }
}

inline bool isDOWValid(const char* str)
{
   // a little FSM to validate the day of the week
   bool good = true;
   if (str[0] == 'S') // Sun, Sat
   {
      if (str[1] == 'u')
      {
         if (str[2] != 'n') // Sun
         {
            good = false;
         }
      }
      else if (str[1] ==  'a')
      {
         if (str[2] != 't') // Sat
         {
            good = false;
         }
      }
      else
      {
         good = false;
      }
   }
   else if (str[0] == 'M') // Mon
   {
      if (str[1] == 'o')
      {
         if (str[2] != 'n')
         {
            good = false;
         }
      }
      else
      {
         good = false;
      }
   }
   else if (str[0] == 'T') // Tue, Thu
   {
      if (str[1] == 'u')
      {
         if (str[2] != 'e') // Tue
         {
            good = false;
         }
      }
      else if (str[1] ==  'h')
      {
         if (str[2] != 'u') // Thu
         {
            good = false;
         }
      }
      else
      {
         good = false;
      }
   }
   else if (str[0] == 'W') // Wed
   {
      if (str[1] == 'e')
      {
         if (str[2] != 'd')
         {
            good = false;
         }
      }
      else
      {
         good = false;
      }
   }
   else if (str[0] == 'F') // Fri
   {
      if (str[1] == 'r')
      {
         if (str[2] != 'i')
         {
            good = false;
         }
      }
      else
      {
         good = false;
      }
   }
   else
   {
      good = false;
   }

   return good;
}

inline bool isLongDOWValid(const String& s)
{
   if ( (s == "Sunday") ||
   (s == "Monday") ||
   (s == "Tuesday") ||
   (s == "Wednesday") ||
   (s == "Thursday") ||
   (s == "Friday") ||
   (s == "Saturday") )
   {
      return true;
   }
   return false;
}

// returns -1 if the month is invalid, 1-12 otherwise
inline int decodeShortMonth(const char* str)
{
   // a little FSM to calculate the month
   if (str[0] == 'J') // Jan, Jun, Jul
   {
      if (str[1] == 'a')
      {
         if (str[2] == 'n') // Jan
         {
            return 1;
         }
      }
      else if (str[1] ==  'u')
      {
         if (str[2] == 'n') // Jun
         {
            return 6;
         }
         else if (str[2] == 'l') // Jul
         {
            return 7;
         }
      }
   }
   else if (str[0] == 'F') // Feb
   {
      if (str[1] == 'e' && str[2] == 'b')
      {
         return 2;
      }
   }
   else if (str[0] == 'M') // Mar, May
   {
      if (str[1] == 'a')
      {
         if (str[2] == 'r') // Mar
         {
            return 3;
         }
         else if (str[2] == 'y') // May
         {
            return 5;
         }
      }
   }
   else if (str[0] == 'A') // Apr, Aug
   {
      if (str[1] == 'p')
      {
         if (str[2] == 'r') // Apr
         {
            return 4;
         }
      }
      else if (str[1] == 'u')
      {
         if (str[2] == 'g') // Aug
         {
            return 8;
         }
      }
   }
   else if (str[0] == 'S') // Sep
   {
      if (str[1] == 'e' && str[2] == 'p')
      {
         return 9;
      }
   }
   else if (str[0] == 'O') // Oct
   {
      if (str[1] == 'c' && str[2] == 't')
      {
         return 10;
      }
   }
   else if (str[0] == 'N') // Nov
   {
      if (str[1] == 'o' && str[2] == 'v')
      {
         return 11;
      }
   }
   else if (str[0] == 'D') // Dec
   {
      if (str[1] == 'e' && str[2] == 'c')
      {
         return 12;
      }
   }

   return -1;
}

// returns -1 if the month is invalid, 1-12 otherwise
inline int decodeLongMonth(const String& str)
{
   if ( str.equals("January") )
   {
      return 1;
   }
   else if ( str.equals("February") )
   {
      return 2;
   }
   else if ( str.equals("March") )
   {
      return 3;
   }
   else if ( str.equals("April") )
   {
      return 4;
   }
   else if ( str.equals("May") )
   {
      return 5;
   }
   else if ( str.equals("June") )
   {
      return 6;
   }
   else if ( str.equals("July") )
   {
      return 7;
   }
   else if ( str.equals("August") )
   {
      return 8;
   }
   else if ( str.equals("September") )
   {
      return 9;
   }
   else if ( str.equals("October") )
   {
      return 10;
   }
   else if ( str.equals("November") )
   {
      return 11;
   }
   else if ( str.equals("December") )
   {
      return 12;
   }
   return -1;
}

// Get the timezone offset (from UTC) for the given timezone.  Valid results
// are in the range -12 to 12, except for the case where LOCAL_TIME_OFFSET is
// returned, in which case UTC should not be used.
const int LOCAL_TIME_OFFSET = -24;
bool getTimeZoneOffset(const String& timezone, int& offset)
{
   int temp_offset = LOCAL_TIME_OFFSET -1;
   if ( timezone.length() == 1 )
   {
      // Single-letter abbrev.
      // This could be simplified into a couple of if statements with some
      // character math, but this should work for now.
      switch ( timezone[0] )
      {
         case 'Y': // Yankee   UTC-12
            temp_offset = -12;
            break;
         case 'X': // Xray     UTC-11
            temp_offset = -11;
            break;
         case 'W': // Whiskey  UTC-10
            temp_offset = -10;
            break;
         case 'V': // Victor   UTC-9
            temp_offset = -9;
            break;
         case 'U': // Uniform  UTC-8
            temp_offset = -8;
            break;
         case 'T': // Tango    UTC-7
            temp_offset = -7;
            break;
         case 'S': // Sierra   UTC-6
            temp_offset = -6;
            break;
         case 'R': // Romeo    UTC-5
            temp_offset = -5;
            break;
         case 'Q': // Quebec   UTC-4
            temp_offset = -4;
            break;
         case 'P': // Papa     UTC-3
            temp_offset = -3;
            break;
         case 'O': // Oscar    UTC-2
            temp_offset = -2;
            break;
         case 'N': // November UTC-1
            temp_offset = -1;
            break;
         case 'Z': // Zulu     UTC
            temp_offset = 0;
            break;
         case 'A': // Aplpha   UTC+1
            temp_offset = 1;
            break;
         case 'B': // Bravo    UTC+2
            temp_offset = 2;
            break;
         case 'C': // Charlie  UTC+3
            temp_offset = 3;
            break;
         case 'D': // Delta    UTC+4
            temp_offset = 4;
            break;
         case 'E': // Echo     UTC+5
            temp_offset = 5;
            break;
         case 'F': // Foxtrot  UTC+6
            temp_offset = 6;
            break;
         case 'G': // Golf     UTC+7
            temp_offset = 7;
            break;
         case 'H': // Hotel    UTC+8
            temp_offset = 8;
            break;
         case 'I': // India    UTC+9
            temp_offset = 9;
            break;
         case 'K': // Kilo     UTC+10
            temp_offset = 10;
            break;
         case 'L': // Lima     UTC+11
            temp_offset = 11;
            break;
         case 'M': // Mike     UTC+12
            temp_offset = 12;
            break;
         case 'J': // Juliet   Always local time
            temp_offset = LOCAL_TIME_OFFSET;
            break;
         default:
            break;
      }
   }
   else if ( timezone == "UTC" ) // Universal Time Coordinated, civil time
   {
      temp_offset = 0;
   }
   // European timezones
   else if ( timezone == "GMT" ) // Greenwich Mean Time   UTC
   {
      temp_offset = 0;
   }
   else if ( timezone == "BST" ) // British Summer Time   UTC+1
   {
      temp_offset = 1;
   }
   else if ( timezone == "IST" ) // Irish Summer Time     UTC+1
   {
      temp_offset = 1;
   }
   else if ( timezone == "WET" ) // Western Europe Time   UTC
   {
      temp_offset = 0;
   }
   else if ( timezone == "WEST" ) // Western Europe Summer Time   UTC+1
   {
      temp_offset = 1;
   }
   else if ( timezone == "CET" ) // Central Europe Time   UTC+1
   {
      temp_offset = 1;
   }
   else if ( timezone == "CEST" ) // Central Europe Summer Time   UTC+2
   {
      temp_offset = 2;
   }
   else if ( timezone == "EET" ) // Eastern Europe Time   UTC+2
   {
      temp_offset = 2;
   }
   else if ( timezone == "EEST" ) // Eastern Europe Summer Time   UTC+3
   {
      temp_offset = 3;
   }
   else if ( timezone == "MSK" ) // Moscow Time   UTC+3
   {
      temp_offset = 3;
   }
   else if ( timezone == "MSD" ) // Moscow Summer Time    UTC+4
   {
      temp_offset = 4;
   }
   // US and Canada
   else if ( timezone == "AST" ) // Atlantic Standard Time        UTC-4
   {
      temp_offset = -4;
   }
   else if ( timezone == "ADT" ) // Atlantic Daylight Saving Time UTC-3
   {
      temp_offset = -3;
   }
   else if ( timezone == "EST" ) // Eastern Standard Time         UTC-5
   {
      // CHECKME! This can also be Australian Eastern Standard Time UTC+10
      // (UTC+11 in Summer)
      temp_offset = -5;
   }
   else if ( timezone == "EDT" ) // Eastern Daylight Saving Time  UTC-4
   {
      temp_offset = -4;
   }
   else if ( timezone == "ET" ) // Eastern Time, either as EST or EDT
   // depending on place and time of year
   {
      // CHECKME! Assuming standard time.
      temp_offset = -5;
   }
   else if ( timezone == "CST" ) // Central Standard Time         UTC-6
   {
      // CHECKME! This can also be Australian Central Standard Time UTC+9.5
      temp_offset = -6;
   }
   else if ( timezone == "CDT" ) // Central Daylight Saving Time  UTC-5
   {
      temp_offset = -5;
   }
   else if ( timezone == "CT" ) // Central Time, either as CST or CDT
   // depending on place and time of year
   {
      // CHECKME! Assuming standard time.
      temp_offset = -6;
   }
   else if ( timezone == "MST" ) // Mountain Standard Time        UTC-7
   {
      temp_offset = -7;
   }
   else if ( timezone == "MDT" ) // Mountain Daylight Saving Time UTC-6
   {
      temp_offset = -6;
   }
   else if ( timezone == "MT" ) // Mountain Time, either as MST or MDT
   // depending on place and time of year
   {
      // CHECKME! Assuming standard time.
      temp_offset = -7;
   }
   else if ( timezone == "PST" ) // Pacific Standard Time         UTC-8
   {
      temp_offset = -8;
   }
   else if ( timezone == "PDT" ) // Pacific Daylight Saving Time  UTC-7
   {
      temp_offset = -7;
   }
   else if ( timezone == "PT" ) // Pacific Time, either as PST or PDT
   // depending on place and time of year
   {
      // CHECKME! Assuming standard time.
      temp_offset = -8;
   }
   else if ( timezone == "HST" ) // Hawaiian Standard Time        UTC-10
   {
      temp_offset = -10;
   }
   else if ( timezone == "AKST" ) // Alaska Standard Time         UTC-9
   {
      temp_offset = -9;
   }
   else if ( timezone == "AKDT" ) // Alaska Standard Daylight Saving Time UTC-8
   {
      temp_offset = -8;
   }
   // Australia
   else if ( timezone == "WST" ) // Western Standard Time         UTC+8
   {
      temp_offset = 8;
   }

   // Check the results of that huge mess.
   if ( temp_offset >= LOCAL_TIME_OFFSET )
   {
      offset = temp_offset;
      return true;
   }
   return false;
}

Int32 getDaysPerMonth(Int32 year, Int32 month)
{
   const Int32 normal_days_per_month[12] =
   { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

   if ( (month >= 1) && (month <= 12) )
   {
      if ( month != 2 )
      {
         return normal_days_per_month[month - 1];
      }

      int leap_year_adjust = 0;

      if ( (year % 4) == 0 )
      {
         // Possibly a leap year.
         if ( (year % 100) == 0 )
         {
            if ( (year % 400) == 0 )
            {
               leap_year_adjust = 1;
            }
         }
         else
         {
            leap_year_adjust = 1;
         }
      }

      return normal_days_per_month[month - 1] + leap_year_adjust;
      // Check to see if it's a leap year.
   }
   return 0;
}

// Adjust the time given (year, month, day, hour) for the given timezone
// offset.
// Note: this is converting FROM local time to UTC, so the timezone offset is
// subtracted instead of added.
void adjustTimeForTimeZone(Int32 timezone_offset, Int32& year, Int32& month,
Int32& day, Int32& hour)
{
   if ( timezone_offset < 0 )
   {
      hour -= timezone_offset;

      if ( hour > 23 )
      {
         ++day;
         hour -= 24;
      }
      // This assumes that the timezone will not shove a date by more than one day.
      if ( day > getDaysPerMonth(year, month) )
      {
         ++month;
         day = 1;
      }
      if ( month > 12 )
      {
         month -= 12;
         ++year;
      }
   }
   else if ( timezone_offset > 0 )
   {
      hour -= timezone_offset;

      if ( hour < 0 )
      {
         --day;
         hour += 24;
      }
      // This assumes that the timezone will not shove a date by more than one day.
      if ( day < 1 )
      {
         --month;
         day += getDaysPerMonth(year, month);
      }
      if ( month < 1 )
      {
         month += 12;
         --year;
      }
   }
}


} // end anonymous namespace

DateTime::DateTime(const String& str)
{
   // CIM format
   if ( str.length() == 25 )
   {
      // validate required characters
      if (  !(str[14] != '.' || (str[21] != '+' && str[21] != '-')) )
      {
         try
         {
            // in CIM, "Fields which are not significant must be
            // replaced with asterisk characters."  We'll convert
            // asterisks to 0s so we can process them.
            String strNoAsterisks(str);
            for (size_t i = 0; i < strNoAsterisks.length(); ++i)
            {
               if (strNoAsterisks[i] == '*')
               {
                  strNoAsterisks[i] = '0';
               }
            }
            Int32 year = strNoAsterisks.substring(0, 4).toInt32();
            Int32 month = strNoAsterisks.substring(4, 2).toInt32();
            Int32 day = strNoAsterisks.substring(6, 2).toInt32();
            Int32 hour = strNoAsterisks.substring(8, 2).toInt32();
            Int32 minute = strNoAsterisks.substring(10, 2).toInt32();
            Int32 second = strNoAsterisks.substring(12, 2).toInt32();
            Int32 microseconds = strNoAsterisks.substring(15, 6).toInt32();

            validateRanges(year, month, day, hour, minute, second, microseconds, str);

            Int32 utc = strNoAsterisks.substring(22, 3).toInt32();
            // adjust the time to utc.  According to the CIM spec:
            // "utc is the offset from UTC in minutes"
            if (str[21] == '+')
            {
               utc = 0 - utc;
            }
            minute += utc;

            set(year, month, day, hour, minute, second,
            microseconds, E_UTC_TIME);
            return;
         }
         catch (StringConversionException&)
         {
            // Instead of throwing another exception here, we'll try to parse it in
            // a more general way below.
         }
      }
   }

   // It didn't return from above, so it's not a CIM datetime.  Try to parse
   // it as a free-form date string.
   if ( !str.empty() )
   {
      // This is a general method of extracting the date.
      // It still assumes english names for months and days of week.

      String weekday;
      String day;
      String time;
      int timezone_number = LOCAL_TIME_OFFSET - 1;
      Int32 month_number = -1;
      String year;

      StringArray tokenized_date = str.tokenize();

      // Attempt to fill in the above list of strings...
      for ( StringArray::const_iterator date_token = tokenized_date.begin();
      date_token != tokenized_date.end();
      ++date_token )
      {
         // Check to see if it's a day of the week.
         if ( isDOWValid( date_token->c_str() ) )
         {
            if ( weekday.empty() )
            {
               if ( date_token->length() > 3 )
               {
                  if ( isLongDOWValid( *date_token ) )
                  {
                     weekday = *date_token;
                  }
                  else
                  {
                     // Invalid long day of week
                     badDateTime(str);
                  }
               }
               else
               {
                  weekday = *date_token;
               }
            }
            else
            {
               // Multiple weekdays.
               badDateTime(str);
            }
         }
         // Only do this comparison if a month has not already been found.
         else if ( (month_number == -1) &&
         (month_number = decodeShortMonth( date_token->c_str() ) ) != -1 )
         {
            if ( date_token->length() > 3 )
            {
               month_number = decodeLongMonth( date_token->c_str() );

               if ( month_number == -1 )
               {
                  // Invalid characters in the long version of the month.
                  badDateTime(str);
               }
            }
         }
         // Get the time, if the time wasn't already set.
         else if ( time.empty() && (date_token->indexOf(":") != String::npos) )
         {
            // This will be checked below... Assume it's correct.
            time = *date_token;
         }
         // If a day hasn't been found, and this is a number, assume it's the day.
         else if ( day.empty() && isdigit((*date_token)[0]) )
         {
            day = *date_token;
         }
         // If a year hasn't been found, and this is a number, assume it's the year.
         else if ( year.empty() && isdigit((*date_token)[0]) )
         {
            year = *date_token;
         }
         else if ( (timezone_number <= LOCAL_TIME_OFFSET) &&
         (date_token->length() >= 1) &&
         (date_token->length() <= 4) &&
         getTimeZoneOffset(*date_token, timezone_number) )
         {
            // Matched the timezone (nothing to do, it's already been set).
         }
         else
         {
            badDateTime(str);
         }

      } // for each token.


      // Done looking at tokens.  Verify that all the required fields are present.
      if ( (month_number >= 1) && !day.empty() && !time.empty() && !year.empty() )
      {
         // We've got enough to construct the date.

         // Parse the time
         StringArray time_fields = time.tokenize(":");

         // We need at least the hour and minute, anything other than H:M:S should
         // be in error.
         if ( (time_fields.size() < 2) || (time_fields.size() > 3) )
         {
            badDateTime(str);
         }

         try
         {

            Int32 hour;
            Int32 minute;
            Int32 second = 0;
            UInt32 microseconds = 0;
            Int32 year_number = year.toInt32();
            Int32 day_number = day.toInt32();

            hour = time_fields[0].toInt32();
            minute = time_fields[1].toInt32();

            if ( time_fields.size() == 3 )
            {
               second = time_fields[2].toInt32();
            }

            validateRanges(year_number, month_number, day_number,
            hour, minute, second, microseconds, str);

            if ( timezone_number <= LOCAL_TIME_OFFSET )
            {
               set(year_number, month_number, day_number, hour,
               minute, second, microseconds, E_LOCAL_TIME);
            }
            else
            {
               // Adjust the time for the timezone.
               // The current numbers have already been validated, so any changes
               // should not do anything unexpected.

               adjustTimeForTimeZone(timezone_number, year_number, month_number, day_number, hour);

               // Check again.
               validateRanges(year_number, month_number, day_number, hour,
                  minute, second, microseconds, str);

               set(year_number, month_number, day_number, hour,
                  minute, second, microseconds, E_UTC_TIME);
            }
         }
         catch (const StringConversionException&)
         {
            badDateTime(str);
         }
      }
      else
      {
         // Not all required fields available.
         badDateTime(str);
      }
   }
   else
   {
      // An empty string.
      badDateTime(str);
   }
}
DateTime::DateTime(time_t t, UInt32 microseconds)
   : m_time(t)
   , m_microseconds(microseconds)
{
}
DateTime::DateTime(int year, int month, int day, int hour, int minute,
   int second, UInt32 microseconds, ETimeOffset timeOffset)
{
   set(year, month, day, hour, minute, second, microseconds, timeOffset);
}
DateTime::~DateTime()
{
}
inline tm
DateTime::getTm(ETimeOffset timeOffset) const
{
   if (timeOffset == E_LOCAL_TIME)
   {
      tm theTime;
      localtime_r(&m_time, &theTime);
      return theTime;
   }
   else // timeOffset == E_UTC_TIME
   {
      tm theTime;
      gmtime_r(&m_time, &theTime);
      return theTime;
   }
}

inline void
DateTime::setTime(tm& tmarg, ETimeOffset timeOffset)
{
   if (timeOffset == E_LOCAL_TIME)
   {
      m_time = ::mktime(&tmarg);
   }
   else // timeOffset == E_UTC_TIME
   {
#ifdef OW_HAVE_TIMEGM
      m_time = ::timegm(&tmarg);
#else
      // timezone is a global that is set by mktime() which is "the
      // difference, in seconds, between Coordinated Universal Time
      // (UTC) and local standard time."
#ifdef OW_NETWARE
      m_time = ::mktime(&tmarg) - _timezone;
#else
      m_time = ::mktime(&tmarg) - ::timezone;
#endif
#endif
   }
   // apparently some implementations of timegm return something other than -1 on error, but still < 0...
   if (m_time < 0)
   {
      char buff[30];
      String extraError;

      if( tmarg.tm_wday < 0 || tmarg.tm_wday > 6 )
      {
         extraError += Format("Invalid weekday: %1. ", tmarg.tm_wday);
         tmarg.tm_wday = 0;
      }

      if( tmarg.tm_mon < 0 || tmarg.tm_mon > 11 )
      {
         extraError += Format("Invalid month: %1. ", tmarg.tm_mon);
         tmarg.tm_mon = 0;
      }

      asctime_r(&tmarg, buff);

      OW_THROW(DateTimeException, Format("Unable to represent time \"%1\" as a time_t. %2", buff, extraError).toString().rtrim().c_str());
   }
}
int
DateTime::getHour(ETimeOffset timeOffset) const
{
   return getTm(timeOffset).tm_hour;
}
int
DateTime::getMinute(ETimeOffset timeOffset) const
{
   return getTm(timeOffset).tm_min;
}
int
DateTime::getSecond(ETimeOffset timeOffset) const
{
   return getTm(timeOffset).tm_sec;
}
UInt32
DateTime::getMicrosecond() const
{
   return m_microseconds;
}
int
DateTime::getDay(ETimeOffset timeOffset) const
{
   return getTm(timeOffset).tm_mday;
}
int
DateTime::getDow(ETimeOffset timeOffset) const
{
   return getTm(timeOffset).tm_wday;
}
int
DateTime::getMonth(ETimeOffset timeOffset) const
{
   return getTm(timeOffset).tm_mon+1;
}
int
DateTime::getYear(ETimeOffset timeOffset) const
{
   return (getTm(timeOffset).tm_year + 1900);
}
time_t
DateTime::get() const
{
   return m_time;
}
void
DateTime::setHour(int hour, ETimeOffset timeOffset)
{
   tm theTime = getTm(timeOffset);
   theTime.tm_hour = hour;
   setTime(theTime, timeOffset);
}
void
DateTime::setMinute(int minute, ETimeOffset timeOffset)
{
   tm theTime = getTm(timeOffset);
   theTime.tm_min = minute;
   setTime(theTime, timeOffset);
}
void
DateTime::setSecond(int second, ETimeOffset timeOffset)
{
   tm theTime = getTm(timeOffset);
   theTime.tm_sec = second;
   setTime(theTime, timeOffset);
}
void
DateTime::setMicrosecond(UInt32 microseconds)
{
   if (microseconds > 999999)
   {
      OW_THROW(DateTimeException, Format("invalid microseconds: %1", microseconds).c_str());
   }
   m_microseconds = microseconds;
}
void
DateTime::setTime(int hour, int minute, int second, ETimeOffset timeOffset)
{
   tm theTime = getTm(timeOffset);
   theTime.tm_hour = hour;
   theTime.tm_min = minute;
   theTime.tm_sec = second;
   setTime(theTime, timeOffset);
}
void
DateTime::setDay(int day, ETimeOffset timeOffset)
{
   tm theTime = getTm(timeOffset);
   theTime.tm_mday = day;
   setTime(theTime, timeOffset);
}
void
DateTime::setMonth(int month, ETimeOffset timeOffset)
{
   if (month == 0)
   {
      OW_THROW(DateTimeException, "invalid month: 0");
   }

   tm theTime = getTm(timeOffset);
   theTime.tm_mon = month-1;
   setTime(theTime, timeOffset);
}
void
DateTime::setYear(int year, ETimeOffset timeOffset)
{
   tm theTime = getTm(timeOffset);
   theTime.tm_year = year - 1900;
   setTime(theTime, timeOffset);
}
void
DateTime::set(int year, int month, int day, int hour, int minute, int second,
   UInt32 microseconds, ETimeOffset timeOffset)
{
   tm tmarg;
   memset(&tmarg, 0, sizeof(tmarg));
   tmarg.tm_year = (year >= 1900) ? year - 1900 : year;
   tmarg.tm_mon = month-1;
   tmarg.tm_mday = day;
   tmarg.tm_hour = hour;
   tmarg.tm_min = minute;
   tmarg.tm_sec = second;
   if (timeOffset == E_UTC_TIME)
   {
      tmarg.tm_isdst = 0; // don't want dst applied to utc time!
   }
   else
   {
      tmarg.tm_isdst = -1; // don't know about daylight savings time
   }
   setTime(tmarg, timeOffset);
   m_microseconds = microseconds;
}
void
DateTime::setToCurrent()
{
#ifdef OW_HAVE_GETTIMEOFDAY
   timeval tv;
   gettimeofday(&tv, NULL);
   m_time = tv.tv_sec;
   m_microseconds = tv.tv_usec;
#else
   m_time = time(NULL);
   m_microseconds = 0;
#endif
}
void
DateTime::addDays(int days)
{
   tm theTime = getTm(E_UTC_TIME);
   theTime.tm_mday += days;
   setTime(theTime, E_UTC_TIME);
}
void
DateTime::addYears(int years)
{
   tm theTime = getTm(E_UTC_TIME);
   theTime.tm_year += years;
   setTime(theTime, E_UTC_TIME);
}
void
DateTime::addMonths(int months)
{
   tm theTime = getTm(E_UTC_TIME);
   theTime.tm_mon += months;
   setTime(theTime, E_UTC_TIME);
}
String
DateTime::toString(ETimeOffset timeOffset) const
{
   tm theTime = getTm(timeOffset);
   char buff[30];
   asctime_r(&theTime, buff);
   String s(buff);
   return s;
}

String DateTime::toString(char const * format, ETimeOffset timeOffset) const
{
   tm theTime = getTm(timeOffset);
   size_t const BUFSZ = 1024;
   char buf[BUFSZ];
   size_t n = strftime(buf, BUFSZ, format, &theTime);
   buf[n >= BUFSZ ? 0 : n] = '\0';
   return String(buf);
}

char const DateTime::DEFAULT_FORMAT[] = "%c";

String
DateTime::toStringGMT() const
{
   return toString(E_UTC_TIME);
}

Int16 DateTime::localTimeAndOffset(time_t t, struct tm & t_loc)
{
   struct tm t_utc;
   struct tm * ptm_utc = ::gmtime_r(&t, &t_utc);
   struct tm * ptm_loc = ::localtime_r(&t, &t_loc);
   if (!ptm_utc || !ptm_loc)
   {
      OW_THROW(DateTimeException, Format("Invalid time_t: %1", t).c_str());
   }
   int min_diff =
      (t_loc.tm_min - t_utc.tm_min) + 60 * (t_loc.tm_hour - t_utc.tm_hour);
   // Note: UTC offsets can be greater than 12 hours, but are guaranteed to
   // be less than 24 hours.
   int day_diff = t_loc.tm_mday - t_utc.tm_mday;
   int const one_day = 24 * 60;
   if (day_diff == 0)
   {
      return min_diff;
   }
   else if (day_diff == 1 || day_diff < -1)
   {
      // if day_diff < -1, then UTC day is last day of month and local day
      // is 1st of next month.
      return min_diff + one_day;
   }
   else /* day_diff == -1 || day_diff > 1 */
   {
      // if day_diff > 1, then UTC day is 1st of month and local day is last
      // day of previous month.
      return min_diff - one_day;
   }
}

void
DateTime::set(time_t t, UInt32 microseconds)
{
   if (t == static_cast<time_t>(-1) || microseconds > 999999)
   {
      OW_THROW(DateTimeException, "Either t == -1 or microseconds > 999999");
   }

   m_time = t;
   m_microseconds = microseconds;
}

// static
DateTime
DateTime::getCurrent()
{
   DateTime current;
   current.setToCurrent();
   return current;
}

DateTime operator-(DateTime const & x, DateTime const & y)
{
   time_t diff = x.get() - y.get();
   Int32 microdiff = (Int32)x.getMicrosecond() - (Int32)y.getMicrosecond();
   if (microdiff < 0)
   {
      --diff;
      microdiff += 1000000;
   }
   return DateTime(diff, (UInt32)microdiff);
}

} // end namespace OW_NAMESPACE

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