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