<?php
/** @class DateClass
*   $Id: DateClass.php 1131 2012-12-18 16:49:40Z elena $
*   @brief extends DateTime class with createFromFormat for php 5.2
*/


class DateClass extends DateTime {

public function getTimestamp(){
    return $this->format ("U");
}

/**
*    This function calculates the number of days between the first and the second date. Arguments must be subclasses of DateTime
**/
static function differenceInDays ($firstDate, $secondDate){
    $firstDateTimeStamp = $firstDate->format("U");
    $secondDateTimeStamp = $secondDate->format("U");
    $rv = round ((($firstDateTimeStamp - $secondDateTimeStamp))/86400);
    return $rv;
}

/**
* This function returns an object of DateClass from $time in format $format. See date() for possible values for $format
**/
static function createFromFormat ($format, $time){
    assert ($format!="");
    if($time==""){
        return new DateClass();
    }

    $regexpArray['Y'] = "(?P<Y>[12][90]\d\d)";       
    $regexpArray['m'] = "(?P<m>0[1-9]|1[012])";
    $regexpArray['d'] = "(?P<d>0[1-9]|[12][0-9]|3[01])";
    $regexpArray['-'] = "[-]";
    $regexpArray['.'] = "[\. /.]";
    $regexpArray[':'] = "[:]"; 
    $regexpArray['/'] = "[\/]";     
    $regexpArray['space'] = "[\s]";
    $regexpArray['H'] = "(?P<H>0[0-9]|1[0-9]|2[0-3])";
    $regexpArray['i'] = "(?P<i>[0-5][0-9])";
    $regexpArray['s'] = "(?P<s>[0-5][0-9])";

    $formatArray = str_split ($format);
    $regex = "";

    // create the regular expression
    foreach($formatArray as $character){
        if ($character==" ") $regex = $regex.$regexpArray['space'];
        elseif (array_key_exists($character, $regexpArray)) $regex = $regex.$regexpArray[$character];
    }
    $regex = "/".$regex."/";

    // get results for regualar expression
    preg_match ($regex, $time, $result);

    // create the init string for the new DateTime
    $initString = $result['Y']."-".$result['m']."-".$result['d'];

// if no value for hours, minutes and seconds was found add 00:00:00
    if (isset($result['H'])) $initString = $initString." ".$result['H'].":".$result['i'].":".$result['s'];
    else {$initString = $initString." 00:00:00";}
     
    $newDate = new DateClass ($initString);
    return $newDate;
    }   
}

?>