interface ExposedFormPluginInterface

interface ExposedFormPluginInterface extends ViewsPluginInterface {
    
    /**
     * Renders the exposed form.
     *
     * This method iterates over each handler configured to expose widgets
     * to the end user and attach those widgets to the exposed form.
     *
     * @param bool $block
     *   (optional) TRUE if the exposed form is being rendered as part of a
     *   block; FALSE (default) if not.
     *
     * @return array
     *   Form build array. This method returns an empty array if the form is
     *   being rendered as a block.
     *
     * @see \Drupal\views\ViewExecutable::build()
     */
    public function renderExposedForm($block = FALSE);
    
    /**
     * Runs before the view is rendered.
     *
     * Implement if your exposed form needs to run code before the view is
     * rendered.
     *
     * @param \Drupal\views\ResultRow[] $values
     *   An array of all ResultRow objects returned from the query.
     *
     * @see \Drupal\views\ViewExecutable::render()
     */
    public function preRender($values);
    
    /**
     * Runs after the view has been rendered.
     *
     * Implement if your exposed form needs to run code after the view is
     * rendered.
     *
     * @param string $output
     *   The rendered output of the view display.
     *
     * @see \Drupal\views\ViewExecutable::render()
     */
    public function postRender(&$output);
    
    /**
     * Runs before the view has been executed.
     *
     * Implement if your exposed form needs to run code before query execution.
     *
     * @see \Drupal\views\Plugin\views\display\DisplayPluginBase::preExecute()
     */
    public function preExecute();
    
    /**
     * Runs after the view has been executed.
     *
     * Implement if your exposed form needs to run code after query execution.
     */
    public function postExecute();
    
    /**
     * Alters the exposed form.
     *
     * The exposed form is built by calling the renderExposedForm() method on
     * this class, and then letting each exposed filter and sort handler add
     * widgets to the form. After that is finished, this method is called to
     * let the class alter the finished form.
     *
     * @param array $form
     *   An associative array containing the structure of the form.
     * @param \Drupal\Core\Form\FormStateInterface $form_state
     *   The current state of the form.
     *
     * @see \Drupal\views\Plugin\views\exposed_form\ExposedFormPluginInterface::renderExposedForm()
     * @see \Drupal\views\Form\ViewsExposedForm::buildForm()
     */
    public function exposedFormAlter(&$form, FormStateInterface $form_state);
    
    /**
     * Validates the exposed form submission.
     *
     * @param array $form
     *   An associative array containing the structure of the form.
     * @param \Drupal\Core\Form\FormStateInterface $form_state
     *   The current state of the form.
     *
     * @see \Drupal\views\Form\ViewsExposedForm::validateForm()
     */
    public function exposedFormValidate(&$form, FormStateInterface $form_state);
    
    /**
     * Submits the exposed form.
     *
     * @param array $form
     *   An associative array containing the structure of the form.
     * @param \Drupal\Core\Form\FormStateInterface $form_state
     *   The current state of the form.
     * @param array $exclude
     *   Array of keys that will not appear in $view->exposed_raw_input; for
     *   example, 'form_build_id'.
     *
     * @see \Drupal\views\Form\ViewsExposedForm::submitForm()
     */
    public function exposedFormSubmit(&$form, FormStateInterface $form_state, &$exclude);

}