56 lines
1.8 KiB
PHP
56 lines
1.8 KiB
PHP
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<?php
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/**
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* CExpressionDependency class file.
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*
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* @author Qiang Xue <qiang.xue@gmail.com>
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* @link http://www.yiiframework.com/
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* @copyright 2008-2013 Yii Software LLC
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* @license http://www.yiiframework.com/license/
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*/
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/**
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* CExpressionDependency represents a dependency based on the result of a PHP expression.
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*
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* CExpressionDependency performs dependency checking based on the
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* result of a PHP {@link expression}.
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* The dependency is reported as unchanged if and only if the result 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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* @author Qiang Xue <qiang.xue@gmail.com>
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* @package system.caching.dependencies
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* @since 1.0
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*/
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class CExpressionDependency extends CCacheDependency
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{
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/**
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* @var string the PHP expression whose result is used to determine the dependency.
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* The expression can also be a valid serializable PHP callback.
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* It will be passed with a parameter which is the dependency object itself.
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*
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* The PHP expression will be evaluated using {@link evaluateExpression}.
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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 {@link http://www.php.net/manual/en/language.expressions.php php manual}.
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*/
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public $expression;
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/**
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* Constructor.
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* @param string $expression the PHP expression whose result is used to determine the dependency.
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*/
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public function __construct($expression='true')
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{
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$this->expression=$expression;
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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 generateDependentData()
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{
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return $this->evaluateExpression($this->expression);
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}
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}
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