GOV/Webservice/PHP/GovTimespan.php

<?php
define('PRECISION_DAY',   2);
define('PRECISION_MONTH', 1);
define('PRECISION_YEAR',  0);
define('NO_BEGIN',  (PHP_MAX_INT*-1)+1);
define('NO_END',  PHP_MAX_INT);
 
class GovTimespan {
   var $begin;
   var $end;
 
   function GovTimespan( $begin, $end, $julianDays = FALSE ) {
      if( $julianDays ) {
         $this->begin = $begin;
         $this->end = $end;
      } else {
         // input is in years
         $this->setBeginDate( $begin, 0, 0);
         $this->setEndDate( $begin, 0, 0);
      }
   }
 
   function hasBeginMonth() {
      return ($this->begin % 10) > 0;
   }
 
   function hasEndMonth() {
      return ($this->end % 10) > 0;
   }
 
   function getBeginYear() {
      $cal = cal_from_jd($this->begin,CAL_GREGORIAN);
      return $cal['year'];
   }
 
   function getEndYear() {
      $cal = cal_from_jd($this->end,CAL_GREGORIAN);
      return $cal['year'];
   }
 
   function setBeginDate( $year, $month, $day ) {
      if( $month == 0 ) { $myMonth = 1;} else {$myMonth = $month;}
      if( $day == 0 ) {$myDay = 1;} else {$myDay = $day;}
      $julianDay = cal_to_jd(CAL_GREGORIAN,$myMonth,$myDay,$year);
 
      $this->begin = ($julianDay * 10) + $this->calculatePrecisionIndicator($month, $day);
   }
 
   function setEndDate( $year, $month, $day ) {
      if( $month == 0 ) { $myMonth = 1;} else {$myMonth = $month;}
      if( $day == 0 ) {$myDay = 1;} else {$myDay = $day;}
      $julianDay = cal_to_jd(CAL_GREGORIAN,$myMonth,$myDay,$year);
 
      $this->end = ($julianDay * 10) + $this->calculatePrecisionIndicator($month, $day);
   }
 
   function calculatePrecisionIndicator( $month, $day ) {
      if( $month == 0 ) return PRECISION_YEAR;
      if( $day == 0 ) return PRECISION_YEAR;
      return PRECISION_DAY;
   }
 
   /** Check if the timespans overlap. */
   function overlaps( $timespan ) {
        if ($timespan == null) {
            $result = true;
        } else {
            if ((!$this->hasBeginMonth() && !$timespan->hasEndMonth()) ||
                    (!$this->hasEndMonth() && !$timespan->hasBeginMonth())) {
                /* Timespans overlap only at a value that contains a year (no month or day).
                 * Be lenient in this case.
                 */
                $result = ($this->getBeginYear() < $timespan->getEndYear()) &&
                    ($this->getEndYear() > $timespan->getBeginYear());
            } else {
                $result = ($this->begin < $timespan->end) && ($this->end > $timespan->begin);
            }
        }
 
        return $result;
   }
}
?>