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\data;
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use Yii;
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use yii\base\BaseObject;
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use yii\web\Link;
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use yii\web\Linkable;
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use yii\web\Request;
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/**
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 * Pagination represents information relevant to pagination of data items.
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 *
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 * When data needs to be rendered in multiple pages, Pagination can be used to
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 * represent information such as [[totalCount|total item count]], [[pageSize|page size]],
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 * [[page|current page]], etc. These information can be passed to [[\yii\widgets\LinkPager|pagers]]
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 * to render pagination buttons or links.
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 *
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 * The following example shows how to create a pagination object and feed it
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 * to a pager.
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 *
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 * Controller action:
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 *
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 * ```php
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 * public function actionIndex()
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 * {
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 *     $query = Article::find()->where(['status' => 1]);
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 *     $countQuery = clone $query;
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 *     $pages = new Pagination(['totalCount' => $countQuery->count()]);
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 *     $models = $query->offset($pages->offset)
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 *         ->limit($pages->limit)
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 *         ->all();
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 *
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 *     return $this->render('index', [
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 *          'models' => $models,
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 *          'pages' => $pages,
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 *     ]);
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 * }
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 * ```
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 *
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 * View:
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 *
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 * ```php
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 * foreach ($models as $model) {
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 *     // display $model here
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 * }
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 *
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 * // display pagination
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 * echo LinkPager::widget([
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 *     'pagination' => $pages,
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 * ]);
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 * ```
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 *
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 * For more details and usage information on Pagination, see the [guide article on pagination](guide:output-pagination).
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 *
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 * @property-read int $limit The limit of the data. This may be used to set the LIMIT value for a SQL
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 * statement for fetching the current page of data. Note that if the page size is infinite, a value -1 will be
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 * returned.
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 * @property-read array $links The links for navigational purpose. The array keys specify the purpose of the
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 * links (e.g. [[LINK_FIRST]]), and the array values are the corresponding URLs.
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 * @property-read int $offset The offset of the data. This may be used to set the OFFSET value for a SQL
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 * statement for fetching the current page of data.
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 * @property int $page The zero-based current page number.
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 * @property-read int $pageCount Number of pages.
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 * @property int $pageSize The number of items per page. If it is less than 1, it means the page size is
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 * infinite, and thus a single page contains all items.
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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 Pagination extends BaseObject implements Linkable
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{
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    const LINK_NEXT = 'next';
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    const LINK_PREV = 'prev';
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    const LINK_FIRST = 'first';
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    const LINK_LAST = 'last';
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    /**
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     * @var string name of the parameter storing the current page index.
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     * @see params
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     */
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    public $pageParam = 'page';
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    /**
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     * @var string name of the parameter storing the page size.
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     * @see params
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     */
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    public $pageSizeParam = 'per-page';
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    /**
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     * @var bool whether to always have the page parameter in the URL created by [[createUrl()]].
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     * If false and [[page]] is 0, the page parameter will not be put in the URL.
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     */
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    public $forcePageParam = true;
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    /**
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     * @var string|null the route of the controller action for displaying the paged contents.
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     * If not set, it means using the currently requested route.
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     */
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    public $route;
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    /**
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     * @var array|null parameters (name => value) that should be used to obtain the current page number
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     * and to create new pagination URLs. If not set, all parameters from $_GET will be used instead.
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     *
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     * In order to add hash to all links use `array_merge($_GET, ['#' => 'my-hash'])`.
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     *
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     * The array element indexed by [[pageParam]] is considered to be the current page number (defaults to 0);
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     * while the element indexed by [[pageSizeParam]] is treated as the page size (defaults to [[defaultPageSize]]).
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     */
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    public $params;
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    /**
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     * @var \yii\web\UrlManager|null the URL manager used for creating pagination URLs. If not set,
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     * the "urlManager" application component will be used.
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     */
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    public $urlManager;
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    /**
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     * @var bool whether to check if [[page]] is within valid range.
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     * When this property is true, the value of [[page]] will always be between 0 and ([[pageCount]]-1).
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     * Because [[pageCount]] relies on the correct value of [[totalCount]] which may not be available
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     * in some cases (e.g. MongoDB), you may want to set this property to be false to disable the page
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     * number validation. By doing so, [[page]] will return the value indexed by [[pageParam]] in [[params]].
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     */
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    public $validatePage = true;
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    /**
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     * @var int total number of items.
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     */
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    public $totalCount = 0;
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    /**
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     * @var int the default page size. This property will be returned by [[pageSize]] when page size
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     * cannot be determined by [[pageSizeParam]] from [[params]].
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     */
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    public $defaultPageSize = 20;
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    /**
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     * @var array|false the page size limits. The first array element defines the minimum page size, and the second
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     * the maximum page size. If this is false, it means [[pageSize]] should always return the value of [[defaultPageSize]].
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     */
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    public $pageSizeLimit = [1, 50];
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    /**
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     * @var int number of items on each page.
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     * If it is less than 1, it means the page size is infinite, and thus a single page contains all items.
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     */
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    private $_pageSize;
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    /**
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     * @return int number of pages
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     */
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    public function getPageCount()
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    {
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        $pageSize = $this->getPageSize();
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        if ($pageSize < 1) {
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            return $this->totalCount > 0 ? 1 : 0;
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        }
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        $totalCount = $this->totalCount < 0 ? 0 : (int) $this->totalCount;
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        return (int) (($totalCount + $pageSize - 1) / $pageSize);
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    }
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    private $_page;
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    /**
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     * Returns the zero-based current page number.
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     * @param bool $recalculate whether to recalculate the current page based on the page size and item count.
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     * @return int the zero-based current page number.
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     */
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    public function getPage($recalculate = false)
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    {
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        if ($this->_page === null || $recalculate) {
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            $page = (int) $this->getQueryParam($this->pageParam, 1) - 1;
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            $this->setPage($page, true);
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        }
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        return $this->_page;
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    }
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    /**
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     * Sets the current page number.
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     * @param int $value the zero-based index of the current page.
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     * @param bool $validatePage whether to validate the page number. Note that in order
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     * to validate the page number, both [[validatePage]] and this parameter must be true.
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     */
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    public function setPage($value, $validatePage = false)
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    {
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        if ($value === null) {
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            $this->_page = null;
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        } else {
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            $value = (int) $value;
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            if ($validatePage && $this->validatePage) {
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                $pageCount = $this->getPageCount();
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                if ($value >= $pageCount) {
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                    $value = $pageCount - 1;
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                }
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            }
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            if ($value < 0) {
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                $value = 0;
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            }
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            $this->_page = $value;
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        }
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    }
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    /**
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     * Returns the number of items per page.
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     * By default, this method will try to determine the page size by [[pageSizeParam]] in [[params]].
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     * If the page size cannot be determined this way, [[defaultPageSize]] will be returned.
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     * @return int the number of items per page. If it is less than 1, it means the page size is infinite,
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     * and thus a single page contains all items.
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     * @see pageSizeLimit
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     */
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    public function getPageSize()
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    {
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        if ($this->_pageSize === null) {
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            if (empty($this->pageSizeLimit) || !isset($this->pageSizeLimit[0], $this->pageSizeLimit[1])) {
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                $pageSize = $this->defaultPageSize;
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                $this->setPageSize($pageSize);
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            } else {
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                $pageSize = (int) $this->getQueryParam($this->pageSizeParam, $this->defaultPageSize);
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                $this->setPageSize($pageSize, true);
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            }
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        }
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        return $this->_pageSize;
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    }
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    /**
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     * @param int $value the number of items per page.
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     * @param bool $validatePageSize whether to validate page size.
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     */
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    public function setPageSize($value, $validatePageSize = false)
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    {
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        if ($value === null) {
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            $this->_pageSize = null;
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        } else {
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            $value = (int) $value;
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            if ($validatePageSize && isset($this->pageSizeLimit[0], $this->pageSizeLimit[1])) {
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                if ($value < $this->pageSizeLimit[0]) {
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                    $value = $this->pageSizeLimit[0];
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                } elseif ($value > $this->pageSizeLimit[1]) {
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                    $value = $this->pageSizeLimit[1];
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                }
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            }
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            $this->_pageSize = $value;
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        }
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    }
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    /**
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     * Creates the URL suitable for pagination with the specified page number.
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     * This method is mainly called by pagers when creating URLs used to perform pagination.
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     * @param int $page the zero-based page number that the URL should point to.
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     * @param int|null $pageSize the number of items on each page. If not set, the value of [[pageSize]] will be used.
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     * @param bool $absolute whether to create an absolute URL. Defaults to `false`.
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     * @return string the created URL
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     * @see params
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     * @see forcePageParam
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     */
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    public function createUrl($page, $pageSize = null, $absolute = false)
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    {
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        $page = (int) $page;
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        $pageSize = (int) $pageSize;
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        if (($params = $this->params) === null) {
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            $request = Yii::$app->getRequest();
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            $params = $request instanceof Request ? $request->getQueryParams() : [];
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        }
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        if ($page > 0 || $page == 0 && $this->forcePageParam) {
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            $params[$this->pageParam] = $page + 1;
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        } else {
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            unset($params[$this->pageParam]);
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        }
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        if ($pageSize <= 0) {
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            $pageSize = $this->getPageSize();
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        }
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        if ($pageSize != $this->defaultPageSize) {
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            $params[$this->pageSizeParam] = $pageSize;
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        } else {
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            unset($params[$this->pageSizeParam]);
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        }
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        $params[0] = $this->route === null ? Yii::$app->controller->getRoute() : $this->route;
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        $urlManager = $this->urlManager === null ? Yii::$app->getUrlManager() : $this->urlManager;
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        if ($absolute) {
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            return $urlManager->createAbsoluteUrl($params);
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        }
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        return $urlManager->createUrl($params);
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    }
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    /**
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     * @return int the offset of the data. This may be used to set the
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     * OFFSET value for a SQL statement for fetching the current page of data.
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     */
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    public function getOffset()
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    {
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        $pageSize = $this->getPageSize();
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        return $pageSize < 1 ? 0 : $this->getPage() * $pageSize;
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    }
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    /**
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     * @return int the limit of the data. This may be used to set the
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     * LIMIT value for a SQL statement for fetching the current page of data.
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     * Note that if the page size is infinite, a value -1 will be returned.
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     */
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    public function getLimit()
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    {
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        $pageSize = $this->getPageSize();
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        return $pageSize < 1 ? -1 : $pageSize;
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    }
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    /**
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     * Returns a whole set of links for navigating to the first, last, next and previous pages.
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     * @param bool $absolute whether the generated URLs should be absolute.
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     * @return array the links for navigational purpose. The array keys specify the purpose of the links (e.g. [[LINK_FIRST]]),
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     * and the array values are the corresponding URLs.
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     */
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    public function getLinks($absolute = false)
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    {
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        $currentPage = $this->getPage();
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        $pageCount = $this->getPageCount();
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        $links = [Link::REL_SELF => $this->createUrl($currentPage, null, $absolute)];
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        if ($pageCount > 0) {
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            $links[self::LINK_FIRST] = $this->createUrl(0, null, $absolute);
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            $links[self::LINK_LAST] = $this->createUrl($pageCount - 1, null, $absolute);
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            if ($currentPage > 0) {
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                $links[self::LINK_PREV] = $this->createUrl($currentPage - 1, null, $absolute);
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            }
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            if ($currentPage < $pageCount - 1) {
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                $links[self::LINK_NEXT] = $this->createUrl($currentPage + 1, null, $absolute);
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            }
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        }
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        return $links;
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    }
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    /**
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     * Returns the value of the specified query parameter.
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     * This method returns the named parameter value from [[params]]. Null is returned if the value does not exist.
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     * @param string $name the parameter name
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     * @param string|null $defaultValue the value to be returned when the specified parameter does not exist in [[params]].
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     * @return string|null the parameter value
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     */
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    protected function getQueryParam($name, $defaultValue = null)
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    {
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        if (($params = $this->params) === null) {
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            $request = Yii::$app->getRequest();
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            $params = $request instanceof Request ? $request->getQueryParams() : [];
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        }
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        return isset($params[$name]) && is_scalar($params[$name]) ? $params[$name] : $defaultValue;
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    }
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}
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