PDateTime.cc

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// -*- C++ -*-

// PDateTime
// Copyright (c) 2002 by Nicolas Chapados

// 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. The name of the authors may not be used to endorse or promote
//     products derived from this software without specific prior written
//     permission.
// 
// THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``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 AUTHORS 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.
// 
// This file is part of the PLearn library. For more information on the PLearn
// library, go to the PLearn Web site at www.plearn.org

/* *******************************************************      
   * $Id: PDateTime.cc,v 1.7 2004/07/21 19:55:18 chapados Exp $
   * This file is part of the PLearn library.
   ******************************************************* */

//#include <limits.h>                 // from stdc
#include "stringutils.h"            // For tostring.
#include "PDateTime.h"
#include "general.h"                // for MISSING_VALUE

namespace PLearn {
using namespace std;

PDateTime::PDateTime()
{
  setMissing();
}

PDateTime::PDateTime(double julian_day)
{
  int jw = (int)((julian_day - 1867216.25)/36524.25);
  int jx = (int)(jw/4);
  int ja = (int)(julian_day + 1 + jw - jx);
  int jb = ja + 1524;
  int jc = (int)((jb - 122.1)/365.25);
  int jd = (int)(365.25*jc);
  int je = (int)((jb - jd)/30.6001);
  int jf = (int)(30.6001*je);

  day = jb - jd - jf;
  month = (je>13) ? je-13 : je-1;
  year = (month>2) ? jc-4716 : jc-4715;

  double fraction = julian_day - floor(julian_day);
  int hh,mm,ss;
  double_to_hhmmss(fraction,hh,mm,ss);
  hour = hh;
  min = mm;
  sec = ss;
}

PDateTime::PDateTime(string date)
{
  // Parse either "YYYY/MM/DD" or "YYYY/MM/DD hh:mm:ss" format
  if ((date.size() == 10 || date.size() == 19) &&
      date[4] == '/' && date[7] == '/' &&
      (date.size() == 19? date[13] == ':' && date[16] == ':' : true)) {
    year = toint(date.substr(0,4));
    month = toint(date.substr(5,2));
    day = toint(date.substr(8,2));
    if (date.size() == 10)
      hour = min = sec = 0;
    else {
      hour = toint(date.substr(11,2));
      min  = toint(date.substr(14,2));
      sec  = toint(date.substr(17,2));
    }
  }
  else
    PLERROR("PDateTime::PDateTime: the passed date-time string is not in "
            "\"YYYY/MM/DD\" or \"YYYY/MM/DD hh:mm:ss\" format");
}

bool PDateTime::isMissing() const
{
  return year == SHRT_MIN && month == 0 && day == 0;
}

void PDateTime::setMissing()
{
  year = SHRT_MIN;
  month = 0;
  day = 0;
}  
  
string PDateTime::info() const
{
  return tostring(year)+ slash+
    right(tostring(int(month)), 2, '0') + slash+
    right(tostring(int(day)),   2, '0') + " "+
    right(tostring(int(hour)),  2, '0') + ":"+
    right(tostring(int(min)),   2, '0') + ":"+
    right(tostring(int(sec)),   2, '0');
}

double PDateTime::toJulianDay() const
{
  if (year < 1582)
    PLERROR("toJulianDay works safely only for year > 1581 (%d)", year);

  double fraction = hhmmss_to_double(hour,min,sec);
  
  int jy = (month>2) ? year : year-1;
  int jm = (month>2) ? month : month+12;
  int ja = (int)(jy/100);
  int jb = (int)(ja/4);
  int jc = 2 - ja + jb;
  int je = (int)(365.25*(jy + 4716));
  int jf = (int)(30.6001*(jm + 1));

  return jc + day + je + jf - 1524 + fraction;
}

double datetime_to_double(const PDateTime& t)
{
  if (t.isMissing())
    return MISSING_VALUE;
  else
    return double((t.year-1900)*10000 + t.month*100 + t.day) +
      hhmmss_to_double(t.hour,t.min,t.sec);
}

PDateTime double_to_datetime(double f)
{
  PDateTime date;                     // missing by default
  if (! is_missing(f)) {
    long d = long(f);
    double fraction = f-d;
    date.year = 1900 + d/10000;
    d %= 10000;
    date.month = d/100;
    date.day = d%100;

    int hh,mm,ss;
    double_to_hhmmss(fraction,hh,mm,ss);
    date.hour = hh;
    date.min  = mm;
    date.sec  = ss;
  }
  return date;
}

double hhmmss_to_double(int hh, int mm, int ss)
{
  // There are 1440 minutes in a day.
  // There are 86400 seconds in a day.
  return double(hh)/24. + double(mm)/1440. + double(ss)/86400;
}

void double_to_hhmmss(double fraction, int& hh, int& mm, int& ss)
{
  hh = int(fraction *= 24);
  fraction -= hh;
  mm = int(fraction *= 60);
  fraction -= mm;
  ss = int(fraction * 60);
}


} // end of namespace PLearn

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