1 files changed, 53 insertions, 0 deletions
diff --git a/framework/caching/dependencies/CExpressionDependency.php b/framework/caching/dependencies/CExpressionDependency.php
new file mode 100644
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+++ b/framework/caching/dependencies/CExpressionDependency.php
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+<?php
+/**
+ * CExpressionDependency 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/
+ */
+
+/**
+ * CExpressionDependency represents a dependency based on the result of a PHP expression.
+ *
+ * CExpressionDependency performs dependency checking based on the
+ * result of a PHP {@link expression}.
+ * The dependency is reported as unchanged if and only if the result is
+ * the same as the one evaluated when storing the data to cache.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @version $Id: CExpressionDependency.php 3515 2011-12-28 12:29:24Z mdomba $
+ * @package system.caching.dependencies
+ * @since 1.0
+ */
+class CExpressionDependency extends CCacheDependency
+{
+	/**
+	 * @var string the PHP expression whose result is used to determine the dependency.
+	 * The expression can also be a valid PHP callback,
+	 * including class method name (array(ClassName/Object, MethodName)),
+	 * or anonymous function (PHP 5.3.0+). The function/method will be passed with a
+	 * parameter which is the dependency object itself.
+	 */
+	public $expression;
+
+	/**
+	 * Constructor.
+	 * @param string $expression the PHP expression whose result is used to determine the dependency.
+	 */
+	public function __construct($expression='true')
+	{
+		$this->expression=$expression;
+	}
+
+	/**
+	 * 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 generateDependentData()
+	{
+		return $this->evaluateExpression($this->expression);
+	}
+}