<?php /** * @link http://www.yiiframework.com/ * @copyright Copyright (c) 2008 Yii Software LLC * @license http://www.yiiframework.com/license/ */ namespace yii\caching; /** * ExpressionDependency represents a dependency based on the result of a PHP expression. * * ExpressionDependency will use `eval()` to evaluate the PHP expression. * The dependency is reported as unchanged if and only if the result of the expression is * the same as the one evaluated when storing the data to cache. * * A PHP expression can be any PHP code that has a value. To learn more about what an expression is, * please refer to the [php manual](http://www.php.net/manual/en/language.expressions.php). * * @author Qiang Xue <qiang.xue@gmail.com> * @since 2.0 */ class ExpressionDependency extends Dependency { /** * @var string the string representation of a PHP expression whose result is used to determine the dependency. * A PHP expression can be any PHP code that has a value. To learn more about what an expression is, * please refer to the [php manual](http://www.php.net/manual/en/language.expressions.php). */ public $expression; /** * @var mixed custom data associated with this dependency. In [[expression]], you may compare the value of * this property with the latest data to determine if the dependency has changed or not. */ public $data; /** * Constructor. * @param string $expression the PHP expression whose result is used to determine the dependency. * @param mixed $data the custom data associated with this dependency * @param array $config name-value pairs that will be used to initialize the object properties */ public function __construct($expression = 'true', $data = null, $config = array()) { $this->expression = $expression; $this->data = $data; parent::__construct($config); } /** * Generates the data needed to determine if dependency has been changed. * This method returns the result of the PHP expression. * @return mixed the data needed to determine if dependency has been changed. */ protected function generateDependencyData() { return eval("return {$this->expression};"); } }