interface PagerParametersInterface

interface PagerParametersInterface {
    
    /**
     * Gets all request URL query parameters that are unrelated to paging.
     *
     * @return array
     *   A URL query parameter array that consists of all components of the
     *   current page request except for those pertaining to paging.
     */
    public function getQueryParameters();
    
    /**
     * Returns the current page being requested for display within a pager.
     *
     * @param int $pager_id
     *   (optional) An integer to distinguish between multiple pagers on one page.
     *
     * @return int
     *   The number of the current requested page, within the pager represented by
     *   $element. This is determined from the URL query parameter
     *   \Drupal::request()->query->get('page'), or 0 by default. Note that this
     *   number may differ from the actual page being displayed. For example, if a
     *   search for "example text" brings up three pages of results, but a user
     *   visits search/node/example+text?page=10, this function will return 10,
     *   even though the default pager implementation adjusts for this and still
     *   displays the third page of search results at that URL.
     */
    public function findPage($pager_id = 0);
    
    /**
     * Gets the request query parameter.
     *
     * @return int[]
     *   Array of pagers. Keys are integers which are the element ID. Values are
     *   the zero-based current page from the request. The first page is 0, the
     *   second page is 1, etc.
     */
    public function getPagerQuery();
    
    /**
     * Gets the 'page' query parameter for the current request.
     *
     * @return string
     *   The 'page' query parameter for the current request. This is a
     *   comma-delimited string of pager element values. Defaults to empty string
     *   if the query does not have a 'page' parameter.
     */
    public function getPagerParameter();

}