yii2

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<?php
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/**
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 * @link https://www.yiiframework.com/
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 * @copyright Copyright (c) 2008 Yii Software LLC
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 * @license https://www.yiiframework.com/license/
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 */
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namespace yii\caching;
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/**
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 * ChainedDependency represents a dependency which is composed of a list of other dependencies.
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 *
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 * When [[dependOnAll]] is true, if any of the dependencies has changed, this dependency is
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 * considered changed; When [[dependOnAll]] is false, if one of the dependencies has NOT changed,
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 * this dependency is considered NOT changed.
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 *
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 * For more details and usage information on Cache, see the [guide article on caching](guide:caching-overview).
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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 ChainedDependency extends Dependency
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{
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    /**
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     * @var Dependency[] list of dependencies that this dependency is composed of.
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     * Each array element must be a dependency object.
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     */
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    public $dependencies = [];
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    /**
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     * @var bool whether this dependency is depending on every dependency in [[dependencies]].
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     * Defaults to true, meaning if any of the dependencies has changed, this dependency is considered changed.
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     * When it is set false, it means if one of the dependencies has NOT changed, this dependency
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     * is considered NOT changed.
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     */
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    public $dependOnAll = true;
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    /**
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     * Evaluates the dependency by generating and saving the data related with dependency.
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     * @param CacheInterface $cache the cache component that is currently evaluating this dependency
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     */
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    public function evaluateDependency($cache)
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    {
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        foreach ($this->dependencies as $dependency) {
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            $dependency->evaluateDependency($cache);
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        }
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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 does nothing in this class.
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     * @param CacheInterface $cache the cache component that is currently evaluating this dependency
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     * @return mixed the data needed to determine if dependency has been changed.
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     */
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    protected function generateDependencyData($cache)
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    {
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        return null;
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    }
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    /**
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     * {@inheritdoc}
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     */
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    public function isChanged($cache)
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    {
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        foreach ($this->dependencies as $dependency) {
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            if ($this->dependOnAll && $dependency->isChanged($cache)) {
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                return true;
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            } elseif (!$this->dependOnAll && !$dependency->isChanged($cache)) {
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                return false;
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            }
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        }
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        return !$this->dependOnAll;
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    }
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}
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