Immutable DateTime

DateTime.php

<?php

namespace InterNations\Component\Date\Value;

use DateTime as DateTimeBase;
use DateTimeZone;
use DateInterval;

class DateTime extends DateTimeBase
{
    protected $frozen = true;

    public function __construct($dateString = null, DateTimeZone $timezone = null)
    {
        if ($timezone) {
            parent::__construct($dateString, $timezone);
        } else {
            parent::__construct($dateString);
        }
    }

    public static function now($microtime = false, DateTimeZone $timezone = null)
    {
        if ($microtime) {
            return new static(date('Y-m-d H:i:s' . substr(microtime(true), 10)), $timezone);
        }
        return new static('now', $timezone);
    }

    public static function createFromFormat($format, $time, $timezone = null)
    {
        if ($timezone) {
            $date = parent::createFromFormat($format, $time, $timezone);
        } else {
            $date = parent::createFromFormat($format, $time);
        }

        if (false === $date) {
            return false;
        }

        return new static($date->format('Y-m-d H:i:s.u'), $timezone);
    }

    public function modify($dateString)
    {
        return $this->_guard(__FUNCTION__, array($dateString));
    }

    public function add($interval)
    {
        return $this->_guard('add', func_get_args());
    }

    public function sub($interval)
    {
        return $this->_guard('sub', func_get_args());
    }

    public function setTimezone($timezone)
    {
        return $this->_guard('setTimezone', func_get_args());
    }

    public function setTime($hour, $minute, $second = null)
    {
        return $this->_guard('setTime', func_get_args());
    }

    public function setDate($year, $month, $day)
    {
        return $this->_guard('setDate', func_get_args());
    }

    public function setISODate($year, $week, $day = 1)
    {
        return $this->_guard('setISODate', func_get_args());
    }

    public function setTimestamp($timestamp)
    {
        return $this->_guard('setTimestamp', func_get_args());
    }

    public function diff($date, $absolute = false)
    {
        return $this->_guard('diff', func_get_args());
    }

    public function isFuture(DateTime $compareDate = null)
    {
        if (!$compareDate) {
            $compareDate = self::now(false, $this->getTimezone());
        }
        return $this > $compareDate;
    }

    public function isPast(DateTime $compareDate = null)
    {
        if (!$compareDate) {
            $compareDate = self::now(false, $this->getTimezone());
        }
        return $this < $compareDate;
    }

    protected function _guard($method, array $arguments)
    {
        if ($this->frozen) {
            $date = clone $this;
            $date->frozen = false;
            call_user_func_array(array($date, $method), $arguments);
            $date->frozen = true;
            return $date;
        } else {
            return call_user_func_array(array('parent', $method), $arguments);
        }
    }
}