<?php
namespace Cron;
use InvalidArgumentException;
/**
* CRON field factory implementing a flyweight factory
* @link http://en.wikipedia.org/wiki/Cron
*/
class FieldFactory
{
/**
* @var array Cache of instantiated fields
*/
private $fields = array();
/**
* Get an instance of a field object for a cron expression position
*
* @param int $position CRON expression position value to retrieve
*
* @return FieldInterface
* @throws InvalidArgumentException if a position is not valid
*/
public function getField($position)
{
if (!isset($this->fields[$position])) {
switch ($position) {
case 0:
$this->fields[$position] = new MinutesField();
break;
case 1:
$this->fields[$position] = new HoursField();
break;
case 2:
$this->fields[$position] = new DayOfMonthField();
break;
case 3:
$this->fields[$position] = new MonthField();
break;
case 4:
$this->fields[$position] = new DayOfWeekField();
break;
default:
throw new InvalidArgumentException(
($position + 1) . ' is not a valid position'
);
}
}
return $this->fields[$position];
}
}