summaryrefslogtreecommitdiff
path: root/framework/caching/dependencies/CCacheDependency.php
blob: ca0f3183611f35042842ee4a449230087877f921 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
<?php
/**
 * CCacheDependency class file.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link http://www.yiiframework.com/
 * @copyright Copyright &copy; 2008-2011 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

/**
 * CCacheDependency is the base class for cache dependency classes.
 *
 * CCacheDependency implements the {@link ICacheDependency} interface.
 * Child classes should override its {@link generateDependentData} for
 * actual dependency checking.
 *
 * @property boolean $hasChanged Whether the dependency has changed.
 * @property mixed $dependentData The data used to determine if dependency has been changed.
 * This data is available after {@link evaluateDependency} is called.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @version $Id: CCacheDependency.php 3426 2011-10-25 00:01:09Z alexander.makarow $
 * @package system.caching.dependencies
 * @since 1.0
 */
class CCacheDependency extends CComponent implements ICacheDependency
{
	private $_data;

	/**
	 * Evaluates the dependency by generating and saving the data related with dependency.
	 * This method is invoked by cache before writing data into it.
	 */
	public function evaluateDependency()
	{
		$this->_data=$this->generateDependentData();
	}

	/**
	 * @return boolean whether the dependency has changed.
	 */
	public function getHasChanged()
	{
		return $this->generateDependentData()!=$this->_data;
	}

	/**
	 * @return mixed the data used to determine if dependency has been changed.
	 * This data is available after {@link evaluateDependency} is called.
	 */
	public function getDependentData()
	{
		return $this->_data;
	}

	/**
	 * Generates the data needed to determine if dependency has been changed.
	 * Derived classes should override this method to generate actual dependent data.
	 * @return mixed the data needed to determine if dependency has been changed.
	 */
	protected function generateDependentData()
	{
		return null;
	}
}