cms/drupal/includes/ajax.inc
changeset 541 e756a8c72c3d
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cms/drupal/includes/ajax.inc	Fri Sep 08 12:04:06 2017 +0200
@@ -0,0 +1,1317 @@
+<?php
+
+/**
+ * @file
+ * Functions for use with Drupal's Ajax framework.
+ */
+
+/**
+ * @defgroup ajax Ajax framework
+ * @{
+ * Functions for Drupal's Ajax framework.
+ *
+ * Drupal's Ajax framework is used to dynamically update parts of a page's HTML
+ * based on data from the server. Upon a specified event, such as a button
+ * click, a callback function is triggered which performs server-side logic and
+ * may return updated markup, which is then replaced on-the-fly with no page
+ * refresh necessary.
+ *
+ * This framework creates a PHP macro language that allows the server to
+ * instruct JavaScript to perform actions on the client browser. When using
+ * forms, it can be used with the #ajax property.
+ * The #ajax property can be used to bind events to the Ajax framework. By
+ * default, #ajax uses 'system/ajax' as its path for submission and thus calls
+ * ajax_form_callback() and a defined #ajax['callback'] function.
+ * However, you may optionally specify a different path to request or a
+ * different callback function to invoke, which can return updated HTML or can
+ * also return a richer set of
+ * @link ajax_commands Ajax framework commands @endlink.
+ *
+ * Standard form handling is as follows:
+ *   - A form element has a #ajax property that includes #ajax['callback'] and
+ *     omits #ajax['path']. See below about using #ajax['path'] to implement
+ *     advanced use-cases that require something other than standard form
+ *     handling.
+ *   - On the specified element, Ajax processing is triggered by a change to
+ *     that element.
+ *   - The browser submits an HTTP POST request to the 'system/ajax' Drupal
+ *     path.
+ *   - The menu page callback for 'system/ajax', ajax_form_callback(), calls
+ *     drupal_process_form() to process the form submission and rebuild the
+ *     form if necessary. The form is processed in much the same way as if it
+ *     were submitted without Ajax, with the same #process functions and
+ *     validation and submission handlers called in either case, making it easy
+ *     to create Ajax-enabled forms that degrade gracefully when JavaScript is
+ *     disabled.
+ *   - After form processing is complete, ajax_form_callback() calls the
+ *     function named by #ajax['callback'], which returns the form element that
+ *     has been updated and needs to be returned to the browser, or
+ *     alternatively, an array of custom Ajax commands.
+ *   - The page delivery callback for 'system/ajax', ajax_deliver(), renders the
+ *     element returned by #ajax['callback'], and returns the JSON string
+ *     created by ajax_render() to the browser.
+ *   - The browser unserializes the returned JSON string into an array of
+ *     command objects and executes each command, resulting in the old page
+ *     content within and including the HTML element specified by
+ *     #ajax['wrapper'] being replaced by the new content returned by
+ *     #ajax['callback'], using a JavaScript animation effect specified by
+ *     #ajax['effect'].
+ *
+ * A simple example of basic Ajax use from the
+ * @link http://drupal.org/project/examples Examples module @endlink follows:
+ * @code
+ * function main_page() {
+ *   return drupal_get_form('ajax_example_simplest');
+ * }
+ *
+ * function ajax_example_simplest($form, &$form_state) {
+ *   $form = array();
+ *   $form['changethis'] = array(
+ *     '#type' => 'select',
+ *     '#options' => array(
+ *       'one' => 'one',
+ *       'two' => 'two',
+ *       'three' => 'three',
+ *     ),
+ *     '#ajax' => array(
+ *       'callback' => 'ajax_example_simplest_callback',
+ *       'wrapper' => 'replace_textfield_div',
+ *      ),
+ *   );
+
+ *   // This entire form element will be replaced with an updated value.
+ *   $form['replace_textfield'] = array(
+ *     '#type' => 'textfield',
+ *     '#title' => t("The default value will be changed"),
+ *     '#description' => t("Say something about why you chose") . "'" .
+ *       (!empty($form_state['values']['changethis'])
+ *       ? $form_state['values']['changethis'] : t("Not changed yet")) . "'",
+ *     '#prefix' => '<div id="replace_textfield_div">',
+ *     '#suffix' => '</div>',
+ *   );
+ *   return $form;
+ * }
+ *
+ * function ajax_example_simplest_callback($form, $form_state) {
+ *   // The form has already been submitted and updated. We can return the replaced
+ *   // item as it is.
+ *   return $form['replace_textfield'];
+ * }
+ * @endcode
+ *
+ * In the above example, the 'changethis' element is Ajax-enabled. The default
+ * #ajax['event'] is 'change', so when the 'changethis' element changes,
+ * an Ajax call is made. The form is submitted and reprocessed, and then the
+ * callback is called. In this case, the form has been automatically
+ * built changing $form['replace_textfield']['#description'], so the callback
+ * just returns that part of the form.
+ *
+ * To implement Ajax handling in a form, add '#ajax' to the form
+ * definition of a field. That field will trigger an Ajax event when it is
+ * clicked (or changed, depending on the kind of field). #ajax supports
+ * the following parameters (either 'path' or 'callback' is required at least):
+ * - #ajax['callback']: The callback to invoke to handle the server side of the
+ *   Ajax event, which will receive a $form and $form_state as arguments, and
+ *   returns a renderable array (most often a form or form fragment), an HTML
+ *   string, or an array of Ajax commands. If returning a renderable array or
+ *   a string, the value will replace the original element named in
+ *   #ajax['wrapper'], and
+ *   theme_status_messages()
+ *   will be prepended to that
+ *   element. (If the status messages are not wanted, return an array
+ *   of Ajax commands instead.)
+ *   #ajax['wrapper']. If an array of Ajax commands is returned, it will be
+ *   executed by the calling code.
+ * - #ajax['path']: The menu path to use for the request. This is often omitted
+ *   and the default is used. This path should map
+ *   to a menu page callback that returns data using ajax_render(). Defaults to
+ *   'system/ajax', which invokes ajax_form_callback(), eventually calling
+ *   the function named in #ajax['callback']. If you use a custom
+ *   path, you must set up the menu entry and handle the entire callback in your
+ *   own code.
+ * - #ajax['wrapper']: The CSS ID of the area to be replaced by the content
+ *   returned by the #ajax['callback'] function. The content returned from
+ *   the callback will replace the entire element named by #ajax['wrapper'].
+ *   The wrapper is usually created using #prefix and #suffix properties in the
+ *   form. Note that this is the wrapper ID, not a CSS selector. So to replace
+ *   the element referred to by the CSS selector #some-selector on the page,
+ *   use #ajax['wrapper'] = 'some-selector', not '#some-selector'.
+ * - #ajax['effect']: The jQuery effect to use when placing the new HTML.
+ *   Defaults to no effect. Valid options are 'none', 'slide', or 'fade'.
+ * - #ajax['speed']: The effect speed to use. Defaults to 'slow'. May be
+ *   'slow', 'fast' or a number in milliseconds which represents the length
+ *   of time the effect should run.
+ * - #ajax['event']: The JavaScript event to respond to. This is normally
+ *   selected automatically for the type of form widget being used, and
+ *   is only needed if you need to override the default behavior.
+ * - #ajax['prevent']: A JavaScript event to prevent when 'event' is triggered.
+ *   Defaults to 'click' for #ajax on #type 'submit', 'button', and
+ *   'image_button'. Multiple events may be specified separated by spaces.
+ *   For example, when binding #ajax behaviors to form buttons, pressing the
+ *   ENTER key within a textfield triggers the 'click' event of the form's first
+ *   submit button. Triggering Ajax in this situation leads to problems, like
+ *   breaking autocomplete textfields. Because of that, Ajax behaviors are bound
+ *   to the 'mousedown' event on form buttons by default. However, binding to
+ *   'mousedown' rather than 'click' means that it is possible to trigger a
+ *   click by pressing the mouse, holding the mouse button down until the Ajax
+ *   request is complete and the button is re-enabled, and then releasing the
+ *   mouse button. For this case, 'prevent' can be set to 'click', so an
+ *   additional event handler is bound to prevent such a click from triggering a
+ *   non-Ajax form submission. This also prevents a textfield's ENTER press
+ *   triggering a button's non-Ajax form submission behavior.
+ * - #ajax['method']: The jQuery method to use to place the new HTML.
+ *   Defaults to 'replaceWith'. May be: 'replaceWith', 'append', 'prepend',
+ *   'before', 'after', or 'html'. See the
+ *   @link http://api.jquery.com/category/manipulation/ jQuery manipulators documentation @endlink
+ *   for more information on these methods.
+ * - #ajax['progress']: Choose either a throbber or progress bar that is
+ *   displayed while awaiting a response from the callback, and add an optional
+ *   message. Possible keys: 'type', 'message', 'url', 'interval'.
+ *   More information is available in the
+ *   @link forms_api_reference.html Form API Reference @endlink
+ *
+ * In addition to using Form API for doing in-form modification, Ajax may be
+ * enabled by adding classes to buttons and links. By adding the 'use-ajax'
+ * class to a link, the link will be loaded via an Ajax call. When using this
+ * method, the href of the link can contain '/nojs/' as part of the path. When
+ * the Ajax framework makes the request, it will convert this to '/ajax/'.
+ * The server is then able to easily tell if this request was made through an
+ * actual Ajax request or in a degraded state, and respond appropriately.
+ *
+ * Similarly, submit buttons can be given the class 'use-ajax-submit'. The
+ * form will then be submitted via Ajax to the path specified in the #action.
+ * Like the ajax-submit class above, this path will have '/nojs/' replaced with
+ * '/ajax/' so that the submit handler can tell if the form was submitted
+ * in a degraded state or not.
+ *
+ * When responding to Ajax requests, the server should do what it needs to do
+ * for that request, then create a commands array. This commands array will
+ * be converted to a JSON object and returned to the client, which will then
+ * iterate over the array and process it like a macro language.
+ *
+ * Each command item is an associative array which will be converted to a
+ * command object on the JavaScript side. $command_item['command'] is the type
+ * of command, e.g. 'alert' or 'replace', and will correspond to a method in the
+ * Drupal.ajax[command] space. The command array may contain any other data that
+ * the command needs to process, e.g. 'method', 'selector', 'settings', etc.
+ *
+ * Commands are usually created with a couple of helper functions, so they
+ * look like this:
+ * @code
+ *   $commands = array();
+ *   // Replace the content of '#object-1' on the page with 'some html here'.
+ *   $commands[] = ajax_command_replace('#object-1', 'some html here');
+ *   // Add a visual "changed" marker to the '#object-1' element.
+ *   $commands[] = ajax_command_changed('#object-1');
+ *   // Menu 'page callback' and #ajax['callback'] functions are supposed to
+ *   // return render arrays. If returning an Ajax commands array, it must be
+ *   // encapsulated in a render array structure.
+ *   return array('#type' => 'ajax', '#commands' => $commands);
+ * @endcode
+ *
+ * When returning an Ajax command array, it is often useful to have
+ * status messages rendered along with other tasks in the command array.
+ * In that case the Ajax commands array may be constructed like this:
+ * @code
+ *   $commands = array();
+ *   $commands[] = ajax_command_replace(NULL, $output);
+ *   $commands[] = ajax_command_prepend(NULL, theme('status_messages'));
+ *   return array('#type' => 'ajax', '#commands' => $commands);
+ * @endcode
+ *
+ * See @link ajax_commands Ajax framework commands @endlink
+ */
+
+/**
+ * Renders a commands array into JSON.
+ *
+ * @param $commands
+ *   A list of macro commands generated by the use of ajax_command_*()
+ *   functions.
+ */
+function ajax_render($commands = array()) {
+  // Although ajax_deliver() does this, some contributed and custom modules
+  // render Ajax responses without using that delivery callback.
+  ajax_set_verification_header();
+
+  // Ajax responses aren't rendered with html.tpl.php, so we have to call
+  // drupal_get_css() and drupal_get_js() here, in order to have new files added
+  // during this request to be loaded by the page. We only want to send back
+  // files that the page hasn't already loaded, so we implement simple diffing
+  // logic using array_diff_key().
+  foreach (array('css', 'js') as $type) {
+    // It is highly suspicious if $_POST['ajax_page_state'][$type] is empty,
+    // since the base page ought to have at least one JS file and one CSS file
+    // loaded. It probably indicates an error, and rather than making the page
+    // reload all of the files, instead we return no new files.
+    if (empty($_POST['ajax_page_state'][$type])) {
+      $items[$type] = array();
+    }
+    else {
+      $function = 'drupal_add_' . $type;
+      $items[$type] = $function();
+      drupal_alter($type, $items[$type]);
+      // @todo Inline CSS and JS items are indexed numerically. These can't be
+      //   reliably diffed with array_diff_key(), since the number can change
+      //   due to factors unrelated to the inline content, so for now, we strip
+      //   the inline items from Ajax responses, and can add support for them
+      //   when drupal_add_css() and drupal_add_js() are changed to use a hash
+      //   of the inline content as the array key.
+      foreach ($items[$type] as $key => $item) {
+        if (is_numeric($key)) {
+          unset($items[$type][$key]);
+        }
+      }
+      // Ensure that the page doesn't reload what it already has.
+      $items[$type] = array_diff_key($items[$type], $_POST['ajax_page_state'][$type]);
+    }
+  }
+
+  // Render the HTML to load these files, and add AJAX commands to insert this
+  // HTML in the page. We pass TRUE as the $skip_alter argument to prevent the
+  // data from being altered again, as we already altered it above. Settings are
+  // handled separately, afterwards.
+  if (isset($items['js']['settings'])) {
+    unset($items['js']['settings']);
+  }
+  $styles = drupal_get_css($items['css'], TRUE);
+  $scripts_footer = drupal_get_js('footer', $items['js'], TRUE);
+  $scripts_header = drupal_get_js('header', $items['js'], TRUE);
+
+  $extra_commands = array();
+  if (!empty($styles)) {
+    $extra_commands[] = ajax_command_add_css($styles);
+  }
+  if (!empty($scripts_header)) {
+    $extra_commands[] = ajax_command_prepend('head', $scripts_header);
+  }
+  if (!empty($scripts_footer)) {
+    $extra_commands[] = ajax_command_append('body', $scripts_footer);
+  }
+  if (!empty($extra_commands)) {
+    $commands = array_merge($extra_commands, $commands);
+  }
+
+  // Now add a command to merge changes and additions to Drupal.settings.
+  $scripts = drupal_add_js();
+  if (!empty($scripts['settings'])) {
+    $settings = $scripts['settings'];
+    array_unshift($commands, ajax_command_settings(drupal_array_merge_deep_array($settings['data']), TRUE));
+  }
+
+  // Allow modules to alter any Ajax response.
+  drupal_alter('ajax_render', $commands);
+
+  return drupal_json_encode($commands);
+}
+
+/**
+ * Gets a form submitted via #ajax during an Ajax callback.
+ *
+ * This will load a form from the form cache used during Ajax operations. It
+ * pulls the form info from $_POST.
+ *
+ * @return
+ *   An array containing the $form, $form_state, $form_id, $form_build_id and an
+ *   initial list of Ajax $commands. Use the list() function to break these
+ *   apart:
+ *   @code
+ *     list($form, $form_state, $form_id, $form_build_id, $commands) = ajax_get_form();
+ *   @endcode
+ */
+function ajax_get_form() {
+  $form_state = form_state_defaults();
+
+  $form_build_id = $_POST['form_build_id'];
+
+  // Get the form from the cache.
+  $form = form_get_cache($form_build_id, $form_state);
+  if (!$form) {
+    // If $form cannot be loaded from the cache, the form_build_id in $_POST
+    // must be invalid, which means that someone performed a POST request onto
+    // system/ajax without actually viewing the concerned form in the browser.
+    // This is likely a hacking attempt as it never happens under normal
+    // circumstances, so we just do nothing.
+    watchdog('ajax', 'Invalid form POST data.', array(), WATCHDOG_WARNING);
+    drupal_exit();
+  }
+
+  // When a page level cache is enabled, the form-build id might have been
+  // replaced from within form_get_cache. If this is the case, it is also
+  // necessary to update it in the browser by issuing an appropriate Ajax
+  // command.
+  $commands = array();
+  if (isset($form['#build_id_old']) && $form['#build_id_old'] != $form['#build_id']) {
+    // If the form build ID has changed, issue an Ajax command to update it.
+    $commands[] = ajax_command_update_build_id($form);
+    $form_build_id = $form['#build_id'];
+  }
+
+  // Since some of the submit handlers are run, redirects need to be disabled.
+  $form_state['no_redirect'] = TRUE;
+
+  // When a form is rebuilt after Ajax processing, its #build_id and #action
+  // should not change.
+  // @see drupal_rebuild_form()
+  $form_state['rebuild_info']['copy']['#build_id'] = TRUE;
+  $form_state['rebuild_info']['copy']['#action'] = TRUE;
+
+  // The form needs to be processed; prepare for that by setting a few internal
+  // variables.
+  $form_state['input'] = $_POST;
+  $form_id = $form['#form_id'];
+
+  return array($form, $form_state, $form_id, $form_build_id, $commands);
+}
+
+/**
+ * Menu callback; handles Ajax requests for the #ajax Form API property.
+ *
+ * This rebuilds the form from cache and invokes the defined #ajax['callback']
+ * to return an Ajax command structure for JavaScript. In case no 'callback' has
+ * been defined, nothing will happen.
+ *
+ * The Form API #ajax property can be set both for buttons and other input
+ * elements.
+ *
+ * This function is also the canonical example of how to implement
+ * #ajax['path']. If processing is required that cannot be accomplished with
+ * a callback, re-implement this function and set #ajax['path'] to the
+ * enhanced function.
+ *
+ * @see system_menu()
+ */
+function ajax_form_callback() {
+  list($form, $form_state, $form_id, $form_build_id, $commands) = ajax_get_form();
+  drupal_process_form($form['#form_id'], $form, $form_state);
+
+  // We need to return the part of the form (or some other content) that needs
+  // to be re-rendered so the browser can update the page with changed content.
+  // Since this is the generic menu callback used by many Ajax elements, it is
+  // up to the #ajax['callback'] function of the element (may or may not be a
+  // button) that triggered the Ajax request to determine what needs to be
+  // rendered.
+  if (!empty($form_state['triggering_element'])) {
+    $callback = $form_state['triggering_element']['#ajax']['callback'];
+  }
+  if (!empty($callback) && is_callable($callback)) {
+    $result = $callback($form, $form_state);
+
+    if (!(is_array($result) && isset($result['#type']) && $result['#type'] == 'ajax')) {
+      // Turn the response into a #type=ajax array if it isn't one already.
+      $result = array(
+        '#type' => 'ajax',
+        '#commands' => ajax_prepare_response($result),
+      );
+    }
+
+    $result['#commands'] = array_merge($commands, $result['#commands']);
+
+    return $result;
+  }
+}
+
+/**
+ * Theme callback for Ajax requests.
+ *
+ * Many different pages can invoke an Ajax request to system/ajax or another
+ * generic Ajax path. It is almost always desired for an Ajax response to be
+ * rendered using the same theme as the base page, because most themes are built
+ * with the assumption that they control the entire page, so if the CSS for two
+ * themes are both loaded for a given page, they may conflict with each other.
+ * For example, Bartik is Drupal's default theme, and Seven is Drupal's default
+ * administration theme. Depending on whether the "Use the administration theme
+ * when editing or creating content" checkbox is checked, the node edit form may
+ * be displayed in either theme, but the Ajax response to the Field module's
+ * "Add another item" button should be rendered using the same theme as the rest
+ * of the page. Therefore, system_menu() sets the 'theme callback' for
+ * 'system/ajax' to this function, and it is recommended that modules
+ * implementing other generic Ajax paths do the same.
+ *
+ * @see system_menu()
+ * @see file_menu()
+ */
+function ajax_base_page_theme() {
+  if (!empty($_POST['ajax_page_state']['theme']) && !empty($_POST['ajax_page_state']['theme_token'])) {
+    $theme = $_POST['ajax_page_state']['theme'];
+    $token = $_POST['ajax_page_state']['theme_token'];
+
+    // Prevent a request forgery from giving a person access to a theme they
+    // shouldn't be otherwise allowed to see. However, since everyone is allowed
+    // to see the default theme, token validation isn't required for that, and
+    // bypassing it allows most use-cases to work even when accessed from the
+    // page cache.
+    if ($theme === variable_get('theme_default', 'bartik') || drupal_valid_token($token, $theme)) {
+      return $theme;
+    }
+  }
+}
+
+/**
+ * Packages and sends the result of a page callback as an Ajax response.
+ *
+ * This function is the equivalent of drupal_deliver_html_page(), but for Ajax
+ * requests. Like that function, it:
+ * - Adds needed HTTP headers.
+ * - Prints rendered output.
+ * - Performs end-of-request tasks.
+ *
+ * @param $page_callback_result
+ *   The result of a page callback. Can be one of:
+ *   - NULL: to indicate no content.
+ *   - An integer menu status constant: to indicate an error condition.
+ *   - A string of HTML content.
+ *   - A renderable array of content.
+ *
+ * @see drupal_deliver_html_page()
+ */
+function ajax_deliver($page_callback_result) {
+  // Browsers do not allow JavaScript to read the contents of a user's local
+  // files. To work around that, the jQuery Form plugin submits forms containing
+  // a file input element to an IFRAME, instead of using XHR. Browsers do not
+  // normally expect JSON strings as content within an IFRAME, so the response
+  // must be customized accordingly.
+  // @see http://malsup.com/jquery/form/#file-upload
+  // @see Drupal.ajax.prototype.beforeSend()
+  $iframe_upload = !empty($_POST['ajax_iframe_upload']);
+
+  // Emit a Content-Type HTTP header if none has been added by the page callback
+  // or by a wrapping delivery callback.
+  if (is_null(drupal_get_http_header('Content-Type'))) {
+    if (!$iframe_upload) {
+      // Standard JSON can be returned to a browser's XHR object, and to
+      // non-browser user agents.
+      // @see http://www.ietf.org/rfc/rfc4627.txt?number=4627
+      drupal_add_http_header('Content-Type', 'application/json; charset=utf-8');
+    }
+    else {
+      // Browser IFRAMEs expect HTML. With most other content types, Internet
+      // Explorer presents the user with a download prompt.
+      drupal_add_http_header('Content-Type', 'text/html; charset=utf-8');
+    }
+  }
+
+  // Let ajax.js know that this response is safe to process.
+  ajax_set_verification_header();
+
+  // Print the response.
+  $commands = ajax_prepare_response($page_callback_result);
+  $json = ajax_render($commands);
+  if (!$iframe_upload) {
+    // Standard JSON can be returned to a browser's XHR object, and to
+    // non-browser user agents.
+    print $json;
+  }
+  else {
+    // Browser IFRAMEs expect HTML. Browser extensions, such as Linkification
+    // and Skype's Browser Highlighter, convert URLs, phone numbers, etc. into
+    // links. This corrupts the JSON response. Protect the integrity of the
+    // JSON data by making it the value of a textarea.
+    // @see http://malsup.com/jquery/form/#file-upload
+    // @see http://drupal.org/node/1009382
+    print '<textarea>' . $json . '</textarea>';
+  }
+
+  // Perform end-of-request tasks.
+  ajax_footer();
+}
+
+/**
+ * Converts the return value of a page callback into an Ajax commands array.
+ *
+ * @param $page_callback_result
+ *   The result of a page callback. Can be one of:
+ *   - NULL: to indicate no content.
+ *   - An integer menu status constant: to indicate an error condition.
+ *   - A string of HTML content.
+ *   - A renderable array of content.
+ *
+ * @return
+ *   An Ajax commands array that can be passed to ajax_render().
+ */
+function ajax_prepare_response($page_callback_result) {
+  $commands = array();
+  if (!isset($page_callback_result)) {
+    // Simply delivering an empty commands array is sufficient. This results
+    // in the Ajax request being completed, but nothing being done to the page.
+  }
+  elseif (is_int($page_callback_result)) {
+    switch ($page_callback_result) {
+      case MENU_NOT_FOUND:
+        $commands[] = ajax_command_alert(t('The requested page could not be found.'));
+        break;
+
+      case MENU_ACCESS_DENIED:
+        $commands[] = ajax_command_alert(t('You are not authorized to access this page.'));
+        break;
+
+      case MENU_SITE_OFFLINE:
+        $commands[] = ajax_command_alert(filter_xss_admin(variable_get('maintenance_mode_message',
+          t('@site is currently under maintenance. We should be back shortly. Thank you for your patience.', array('@site' => variable_get('site_name', 'Drupal'))))));
+        break;
+    }
+  }
+  elseif (is_array($page_callback_result) && isset($page_callback_result['#type']) && ($page_callback_result['#type'] == 'ajax')) {
+    // Complex Ajax callbacks can return a result that contains an error message
+    // or a specific set of commands to send to the browser.
+    $page_callback_result += element_info('ajax');
+    $error = $page_callback_result['#error'];
+    if (isset($error) && $error !== FALSE) {
+      if ((empty($error) || $error === TRUE)) {
+        $error = t('An error occurred while handling the request: The server received invalid input.');
+      }
+      $commands[] = ajax_command_alert($error);
+    }
+    else {
+      $commands = $page_callback_result['#commands'];
+    }
+  }
+  else {
+    // Like normal page callbacks, simple Ajax callbacks can return HTML
+    // content, as a string or render array. This HTML is inserted in some
+    // relationship to #ajax['wrapper'], as determined by which jQuery DOM
+    // manipulation method is used. The method used is specified by
+    // #ajax['method']. The default method is 'replaceWith', which completely
+    // replaces the old wrapper element and its content with the new HTML.
+    $html = is_string($page_callback_result) ? $page_callback_result : drupal_render($page_callback_result);
+    $commands[] = ajax_command_insert(NULL, $html);
+    // Add the status messages inside the new content's wrapper element, so that
+    // on subsequent Ajax requests, it is treated as old content.
+    $commands[] = ajax_command_prepend(NULL, theme('status_messages'));
+  }
+
+  return $commands;
+}
+
+/**
+ * Sets a response header for ajax.js to trust the response body.
+ *
+ * It is not safe to invoke Ajax commands within user-uploaded files, so this
+ * header protects against those being invoked.
+ *
+ * @see Drupal.ajax.options.success()
+ */
+function ajax_set_verification_header() {
+  $added = &drupal_static(__FUNCTION__);
+
+  // User-uploaded files cannot set any response headers, so a custom header is
+  // used to indicate to ajax.js that this response is safe. Note that most
+  // Ajax requests bound using the Form API will be protected by having the URL
+  // flagged as trusted in Drupal.settings, so this header is used only for
+  // things like custom markup that gets Ajax behaviors attached.
+  if (empty($added)) {
+    drupal_add_http_header('X-Drupal-Ajax-Token', '1');
+    // Avoid sending the header twice.
+    $added = TRUE;
+  }
+}
+
+/**
+ * Performs end-of-Ajax-request tasks.
+ *
+ * This function is the equivalent of drupal_page_footer(), but for Ajax
+ * requests.
+ *
+ * @see drupal_page_footer()
+ */
+function ajax_footer() {
+  // Even for Ajax requests, invoke hook_exit() implementations. There may be
+  // modules that need very fast Ajax responses, and therefore, run Ajax
+  // requests with an early bootstrap.
+  if (drupal_get_bootstrap_phase() == DRUPAL_BOOTSTRAP_FULL && (!defined('MAINTENANCE_MODE') || MAINTENANCE_MODE != 'update')) {
+    module_invoke_all('exit');
+  }
+
+  // Commit the user session. See above comment about the possibility of this
+  // function running without session.inc loaded.
+  if (function_exists('drupal_session_commit')) {
+    drupal_session_commit();
+  }
+}
+
+/**
+ * Form element processing handler for the #ajax form property.
+ *
+ * @param $element
+ *   An associative array containing the properties of the element.
+ *
+ * @return
+ *   The processed element.
+ *
+ * @see ajax_pre_render_element()
+ */
+function ajax_process_form($element, &$form_state) {
+  $element = ajax_pre_render_element($element);
+  if (!empty($element['#ajax_processed'])) {
+    $form_state['cache'] = TRUE;
+  }
+  return $element;
+}
+
+/**
+ * Adds Ajax information about an element to communicate with JavaScript.
+ *
+ * If #ajax['path'] is set on an element, this additional JavaScript is added
+ * to the page header to attach the Ajax behaviors. See ajax.js for more
+ * information.
+ *
+ * @param $element
+ *   An associative array containing the properties of the element.
+ *   Properties used:
+ *   - #ajax['event']
+ *   - #ajax['prevent']
+ *   - #ajax['path']
+ *   - #ajax['options']
+ *   - #ajax['wrapper']
+ *   - #ajax['parameters']
+ *   - #ajax['effect']
+ *
+ * @return
+ *   The processed element with the necessary JavaScript attached to it.
+ */
+function ajax_pre_render_element($element) {
+  // Skip already processed elements.
+  if (isset($element['#ajax_processed'])) {
+    return $element;
+  }
+  // Initialize #ajax_processed, so we do not process this element again.
+  $element['#ajax_processed'] = FALSE;
+
+  // Nothing to do if there is neither a callback nor a path.
+  if (!(isset($element['#ajax']['callback']) || isset($element['#ajax']['path']))) {
+    return $element;
+  }
+
+  // Add a reasonable default event handler if none was specified.
+  if (isset($element['#ajax']) && !isset($element['#ajax']['event'])) {
+    switch ($element['#type']) {
+      case 'submit':
+      case 'button':
+      case 'image_button':
+        // Pressing the ENTER key within a textfield triggers the click event of
+        // the form's first submit button. Triggering Ajax in this situation
+        // leads to problems, like breaking autocomplete textfields, so we bind
+        // to mousedown instead of click.
+        // @see http://drupal.org/node/216059
+        $element['#ajax']['event'] = 'mousedown';
+        // Retain keyboard accessibility by setting 'keypress'. This causes
+        // ajax.js to trigger 'event' when SPACE or ENTER are pressed while the
+        // button has focus.
+        $element['#ajax']['keypress'] = TRUE;
+        // Binding to mousedown rather than click means that it is possible to
+        // trigger a click by pressing the mouse, holding the mouse button down
+        // until the Ajax request is complete and the button is re-enabled, and
+        // then releasing the mouse button. Set 'prevent' so that ajax.js binds
+        // an additional handler to prevent such a click from triggering a
+        // non-Ajax form submission. This also prevents a textfield's ENTER
+        // press triggering this button's non-Ajax form submission behavior.
+        if (!isset($element['#ajax']['prevent'])) {
+          $element['#ajax']['prevent'] = 'click';
+        }
+        break;
+
+      case 'password':
+      case 'textfield':
+      case 'textarea':
+        $element['#ajax']['event'] = 'blur';
+        break;
+
+      case 'radio':
+      case 'checkbox':
+      case 'select':
+        $element['#ajax']['event'] = 'change';
+        break;
+
+      case 'link':
+        $element['#ajax']['event'] = 'click';
+        break;
+
+      default:
+        return $element;
+    }
+  }
+
+  // Attach JavaScript settings to the element.
+  if (isset($element['#ajax']['event'])) {
+    $element['#attached']['library'][] = array('system', 'jquery.form');
+    $element['#attached']['library'][] = array('system', 'drupal.ajax');
+
+    $settings = $element['#ajax'];
+
+    // Assign default settings.
+    $settings += array(
+      'path' => 'system/ajax',
+      'options' => array(),
+    );
+
+    // @todo Legacy support. Remove in Drupal 8.
+    if (isset($settings['method']) && $settings['method'] == 'replace') {
+      $settings['method'] = 'replaceWith';
+    }
+
+    // Change path to URL.
+    $settings['url'] = url($settings['path'], $settings['options']);
+    unset($settings['path'], $settings['options']);
+
+    // Add special data to $settings['submit'] so that when this element
+    // triggers an Ajax submission, Drupal's form processing can determine which
+    // element triggered it.
+    // @see _form_element_triggered_scripted_submission()
+    if (isset($settings['trigger_as'])) {
+      // An element can add a 'trigger_as' key within #ajax to make the element
+      // submit as though another one (for example, a non-button can use this
+      // to submit the form as though a button were clicked). When using this,
+      // the 'name' key is always required to identify the element to trigger
+      // as. The 'value' key is optional, and only needed when multiple elements
+      // share the same name, which is commonly the case for buttons.
+      $settings['submit']['_triggering_element_name'] = $settings['trigger_as']['name'];
+      if (isset($settings['trigger_as']['value'])) {
+        $settings['submit']['_triggering_element_value'] = $settings['trigger_as']['value'];
+      }
+      unset($settings['trigger_as']);
+    }
+    elseif (isset($element['#name'])) {
+      // Most of the time, elements can submit as themselves, in which case the
+      // 'trigger_as' key isn't needed, and the element's name is used.
+      $settings['submit']['_triggering_element_name'] = $element['#name'];
+      // If the element is a (non-image) button, its name may not identify it
+      // uniquely, in which case a match on value is also needed.
+      // @see _form_button_was_clicked()
+      if (isset($element['#button_type']) && empty($element['#has_garbage_value'])) {
+        $settings['submit']['_triggering_element_value'] = $element['#value'];
+      }
+    }
+
+    // Convert a simple #ajax['progress'] string into an array.
+    if (isset($settings['progress']) && is_string($settings['progress'])) {
+      $settings['progress'] = array('type' => $settings['progress']);
+    }
+    // Change progress path to a full URL.
+    if (isset($settings['progress']['path'])) {
+      $settings['progress']['url'] = url($settings['progress']['path']);
+      unset($settings['progress']['path']);
+    }
+
+    $element['#attached']['js'][] = array(
+      'type' => 'setting',
+      'data' => array(
+        'ajax' => array($element['#id'] => $settings),
+        'urlIsAjaxTrusted' => array(
+          $settings['url'] => TRUE,
+        ),
+      ),
+    );
+
+    // Indicate that Ajax processing was successful.
+    $element['#ajax_processed'] = TRUE;
+  }
+  return $element;
+}
+
+/**
+ * @} End of "defgroup ajax".
+ */
+
+/**
+ * @defgroup ajax_commands Ajax framework commands
+ * @{
+ * Functions to create various Ajax commands.
+ *
+ * These functions can be used to create arrays for use with the
+ * ajax_render() function.
+ */
+
+/**
+ * Creates a Drupal Ajax 'alert' command.
+ *
+ * The 'alert' command instructs the client to display a JavaScript alert
+ * dialog box.
+ *
+ * This command is implemented by Drupal.ajax.prototype.commands.alert()
+ * defined in misc/ajax.js.
+ *
+ * @param $text
+ *   The message string to display to the user.
+ *
+ * @return
+ *   An array suitable for use with the ajax_render() function.
+ */
+function ajax_command_alert($text) {
+  return array(
+    'command' => 'alert',
+    'text' => $text,
+  );
+}
+
+/**
+ * Creates a Drupal Ajax 'insert' command using the method in #ajax['method'].
+ *
+ * This command instructs the client to insert the given HTML using whichever
+ * jQuery DOM manipulation method has been specified in the #ajax['method']
+ * variable of the element that triggered the request.
+ *
+ * This command is implemented by Drupal.ajax.prototype.commands.insert()
+ * defined in misc/ajax.js.
+ *
+ * @param $selector
+ *   A jQuery selector string. If the command is a response to a request from
+ *   an #ajax form element then this value can be NULL.
+ * @param $html
+ *   The data to use with the jQuery method.
+ * @param $settings
+ *   An optional array of settings that will be used for this command only.
+ *
+ * @return
+ *   An array suitable for use with the ajax_render() function.
+ */
+function ajax_command_insert($selector, $html, $settings = NULL) {
+  return array(
+    'command' => 'insert',
+    'method' => NULL,
+    'selector' => $selector,
+    'data' => $html,
+    'settings' => $settings,
+  );
+}
+
+/**
+ * Creates a Drupal Ajax 'insert/replaceWith' command.
+ *
+ * The 'insert/replaceWith' command instructs the client to use jQuery's
+ * replaceWith() method to replace each element matched matched by the given
+ * selector with the given HTML.
+ *
+ * This command is implemented by Drupal.ajax.prototype.commands.insert()
+ * defined in misc/ajax.js.
+ *
+ * @param $selector
+ *   A jQuery selector string. If the command is a response to a request from
+ *   an #ajax form element then this value can be NULL.
+ * @param $html
+ *   The data to use with the jQuery replaceWith() method.
+ * @param $settings
+ *   An optional array of settings that will be used for this command only.
+ *
+ * @return
+ *   An array suitable for use with the ajax_render() function.
+ *
+ * See
+ * @link http://docs.jquery.com/Manipulation/replaceWith#content jQuery replaceWith command @endlink
+ */
+function ajax_command_replace($selector, $html, $settings = NULL) {
+  return array(
+    'command' => 'insert',
+    'method' => 'replaceWith',
+    'selector' => $selector,
+    'data' => $html,
+    'settings' => $settings,
+  );
+}
+
+/**
+ * Creates a Drupal Ajax 'insert/html' command.
+ *
+ * The 'insert/html' command instructs the client to use jQuery's html()
+ * method to set the HTML content of each element matched by the given
+ * selector while leaving the outer tags intact.
+ *
+ * This command is implemented by Drupal.ajax.prototype.commands.insert()
+ * defined in misc/ajax.js.
+ *
+ * @param $selector
+ *   A jQuery selector string. If the command is a response to a request from
+ *   an #ajax form element then this value can be NULL.
+ * @param $html
+ *   The data to use with the jQuery html() method.
+ * @param $settings
+ *   An optional array of settings that will be used for this command only.
+ *
+ * @return
+ *   An array suitable for use with the ajax_render() function.
+ *
+ * @see http://docs.jquery.com/Attributes/html#val
+ */
+function ajax_command_html($selector, $html, $settings = NULL) {
+  return array(
+    'command' => 'insert',
+    'method' => 'html',
+    'selector' => $selector,
+    'data' => $html,
+    'settings' => $settings,
+  );
+}
+
+/**
+ * Creates a Drupal Ajax 'insert/prepend' command.
+ *
+ * The 'insert/prepend' command instructs the client to use jQuery's prepend()
+ * method to prepend the given HTML content to the inside each element matched
+ * by the given selector.
+ *
+ * This command is implemented by Drupal.ajax.prototype.commands.insert()
+ * defined in misc/ajax.js.
+ *
+ * @param $selector
+ *   A jQuery selector string. If the command is a response to a request from
+ *   an #ajax form element then this value can be NULL.
+ * @param $html
+ *   The data to use with the jQuery prepend() method.
+ * @param $settings
+ *   An optional array of settings that will be used for this command only.
+ *
+ * @return
+ *   An array suitable for use with the ajax_render() function.
+ *
+ * @see http://docs.jquery.com/Manipulation/prepend#content
+ */
+function ajax_command_prepend($selector, $html, $settings = NULL) {
+  return array(
+    'command' => 'insert',
+    'method' => 'prepend',
+    'selector' => $selector,
+    'data' => $html,
+    'settings' => $settings,
+  );
+}
+
+/**
+ * Creates a Drupal Ajax 'insert/append' command.
+ *
+ * The 'insert/append' command instructs the client to use jQuery's append()
+ * method to append the given HTML content to the inside of each element matched
+ * by the given selector.
+ *
+ * This command is implemented by Drupal.ajax.prototype.commands.insert()
+ * defined in misc/ajax.js.
+ *
+ * @param $selector
+ *   A jQuery selector string. If the command is a response to a request from
+ *   an #ajax form element then this value can be NULL.
+ * @param $html
+ *   The data to use with the jQuery append() method.
+ * @param $settings
+ *   An optional array of settings that will be used for this command only.
+ *
+ * @return
+ *   An array suitable for use with the ajax_render() function.
+ *
+ * @see http://docs.jquery.com/Manipulation/append#content
+ */
+function ajax_command_append($selector, $html, $settings = NULL) {
+  return array(
+    'command' => 'insert',
+    'method' => 'append',
+    'selector' => $selector,
+    'data' => $html,
+    'settings' => $settings,
+  );
+}
+
+/**
+ * Creates a Drupal Ajax 'insert/after' command.
+ *
+ * The 'insert/after' command instructs the client to use jQuery's after()
+ * method to insert the given HTML content after each element matched by
+ * the given selector.
+ *
+ * This command is implemented by Drupal.ajax.prototype.commands.insert()
+ * defined in misc/ajax.js.
+ *
+ * @param $selector
+ *   A jQuery selector string. If the command is a response to a request from
+ *   an #ajax form element then this value can be NULL.
+ * @param $html
+ *   The data to use with the jQuery after() method.
+ * @param $settings
+ *   An optional array of settings that will be used for this command only.
+ *
+ * @return
+ *   An array suitable for use with the ajax_render() function.
+ *
+ * @see http://docs.jquery.com/Manipulation/after#content
+ */
+function ajax_command_after($selector, $html, $settings = NULL) {
+  return array(
+    'command' => 'insert',
+    'method' => 'after',
+    'selector' => $selector,
+    'data' => $html,
+    'settings' => $settings,
+  );
+}
+
+/**
+ * Creates a Drupal Ajax 'insert/before' command.
+ *
+ * The 'insert/before' command instructs the client to use jQuery's before()
+ * method to insert the given HTML content before each of elements matched by
+ * the given selector.
+ *
+ * This command is implemented by Drupal.ajax.prototype.commands.insert()
+ * defined in misc/ajax.js.
+ *
+ * @param $selector
+ *   A jQuery selector string. If the command is a response to a request from
+ *   an #ajax form element then this value can be NULL.
+ * @param $html
+ *   The data to use with the jQuery before() method.
+ * @param $settings
+ *   An optional array of settings that will be used for this command only.
+ *
+ * @return
+ *   An array suitable for use with the ajax_render() function.
+ *
+ * @see http://docs.jquery.com/Manipulation/before#content
+ */
+function ajax_command_before($selector, $html, $settings = NULL) {
+  return array(
+    'command' => 'insert',
+    'method' => 'before',
+    'selector' => $selector,
+    'data' => $html,
+    'settings' => $settings,
+  );
+}
+
+/**
+ * Creates a Drupal Ajax 'remove' command.
+ *
+ * The 'remove' command instructs the client to use jQuery's remove() method
+ * to remove each of elements matched by the given selector, and everything
+ * within them.
+ *
+ * This command is implemented by Drupal.ajax.prototype.commands.remove()
+ * defined in misc/ajax.js.
+ *
+ * @param $selector
+ *   A jQuery selector string. If the command is a response to a request from
+ *   an #ajax form element then this value can be NULL.
+ *
+ * @return
+ *   An array suitable for use with the ajax_render() function.
+ *
+ * @see http://docs.jquery.com/Manipulation/remove#expr
+ */
+function ajax_command_remove($selector) {
+  return array(
+    'command' => 'remove',
+    'selector' => $selector,
+  );
+}
+
+/**
+ * Creates a Drupal Ajax 'changed' command.
+ *
+ * This command instructs the client to mark each of the elements matched by the
+ * given selector as 'ajax-changed'.
+ *
+ * This command is implemented by Drupal.ajax.prototype.commands.changed()
+ * defined in misc/ajax.js.
+ *
+ * @param $selector
+ *   A jQuery selector string. If the command is a response to a request from
+ *   an #ajax form element then this value can be NULL.
+ * @param $asterisk
+ *   An optional CSS selector which must be inside $selector. If specified,
+ *   an asterisk will be appended to the HTML inside the $asterisk selector.
+ *
+ * @return
+ *   An array suitable for use with the ajax_render() function.
+ */
+function ajax_command_changed($selector, $asterisk = '') {
+  return array(
+    'command' => 'changed',
+    'selector' => $selector,
+    'asterisk' => $asterisk,
+  );
+}
+
+/**
+ * Creates a Drupal Ajax 'css' command.
+ *
+ * The 'css' command will instruct the client to use the jQuery css() method
+ * to apply the CSS arguments to elements matched by the given selector.
+ *
+ * This command is implemented by Drupal.ajax.prototype.commands.css()
+ * defined in misc/ajax.js.
+ *
+ * @param $selector
+ *   A jQuery selector string. If the command is a response to a request from
+ *   an #ajax form element then this value can be NULL.
+ * @param $argument
+ *   An array of key/value pairs to set in the CSS for the selector.
+ *
+ * @return
+ *   An array suitable for use with the ajax_render() function.
+ *
+ * @see http://docs.jquery.com/CSS/css#properties
+ */
+function ajax_command_css($selector, $argument) {
+  return array(
+    'command' => 'css',
+    'selector' => $selector,
+    'argument' => $argument,
+  );
+}
+
+/**
+ * Creates a Drupal Ajax 'settings' command.
+ *
+ * The 'settings' command instructs the client either to use the given array as
+ * the settings for ajax-loaded content or to extend Drupal.settings with the
+ * given array, depending on the value of the $merge parameter.
+ *
+ * This command is implemented by Drupal.ajax.prototype.commands.settings()
+ * defined in misc/ajax.js.
+ *
+ * @param $argument
+ *   An array of key/value pairs to add to the settings. This will be utilized
+ *   for all commands after this if they do not include their own settings
+ *   array.
+ * @param $merge
+ *   Whether or not the passed settings in $argument should be merged into the
+ *   global Drupal.settings on the page. By default (FALSE), the settings that
+ *   are passed to Drupal.attachBehaviors will not include the global
+ *   Drupal.settings.
+ *
+ * @return
+ *   An array suitable for use with the ajax_render() function.
+ */
+function ajax_command_settings($argument, $merge = FALSE) {
+  return array(
+    'command' => 'settings',
+    'settings' => $argument,
+    'merge' => $merge,
+  );
+}
+
+/**
+ * Creates a Drupal Ajax 'data' command.
+ *
+ * The 'data' command instructs the client to attach the name=value pair of
+ * data to the selector via jQuery's data cache.
+ *
+ * This command is implemented by Drupal.ajax.prototype.commands.data()
+ * defined in misc/ajax.js.
+ *
+ * @param $selector
+ *   A jQuery selector string. If the command is a response to a request from
+ *   an #ajax form element then this value can be NULL.
+ * @param $name
+ *   The name or key (in the key value pair) of the data attached to this
+ *   selector.
+ * @param $value
+ *   The value of the data. Not just limited to strings can be any format.
+ *
+ * @return
+ *   An array suitable for use with the ajax_render() function.
+ *
+ * @see http://docs.jquery.com/Core/data#namevalue
+ */
+function ajax_command_data($selector, $name, $value) {
+  return array(
+    'command' => 'data',
+    'selector' => $selector,
+    'name' => $name,
+    'value' => $value,
+  );
+}
+
+/**
+ * Creates a Drupal Ajax 'invoke' command.
+ *
+ * The 'invoke' command will instruct the client to invoke the given jQuery
+ * method with the supplied arguments on the elements matched by the given
+ * selector. Intended for simple jQuery commands, such as attr(), addClass(),
+ * removeClass(), toggleClass(), etc.
+ *
+ * This command is implemented by Drupal.ajax.prototype.commands.invoke()
+ * defined in misc/ajax.js.
+ *
+ * @param $selector
+ *   A jQuery selector string. If the command is a response to a request from
+ *   an #ajax form element then this value can be NULL.
+ * @param $method
+ *   The jQuery method to invoke.
+ * @param $arguments
+ *   (optional) A list of arguments to the jQuery $method, if any.
+ *
+ * @return
+ *   An array suitable for use with the ajax_render() function.
+ */
+function ajax_command_invoke($selector, $method, array $arguments = array()) {
+  return array(
+    'command' => 'invoke',
+    'selector' => $selector,
+    'method' => $method,
+    'arguments' => $arguments,
+  );
+}
+
+/**
+ * Creates a Drupal Ajax 'restripe' command.
+ *
+ * The 'restripe' command instructs the client to restripe a table. This is
+ * usually used after a table has been modified by a replace or append command.
+ *
+ * This command is implemented by Drupal.ajax.prototype.commands.restripe()
+ * defined in misc/ajax.js.
+ *
+ * @param $selector
+ *   A jQuery selector string.
+ *
+ * @return
+ *   An array suitable for use with the ajax_render() function.
+ */
+function ajax_command_restripe($selector) {
+  return array(
+    'command' => 'restripe',
+    'selector' => $selector,
+  );
+}
+
+/**
+ * Creates a Drupal Ajax 'update_build_id' command.
+ *
+ * This command updates the value of a hidden form_build_id input element on a
+ * form. It requires the form passed in to have keys for both the old build ID
+ * in #build_id_old and the new build ID in #build_id.
+ *
+ * The primary use case for this Ajax command is to serve a new build ID to a
+ * form served from the cache to an anonymous user, preventing one anonymous
+ * user from accessing the form state of another anonymous users on Ajax enabled
+ * forms.
+ *
+ * @param $form
+ *   The form array representing the form whose build ID should be updated.
+ */
+function ajax_command_update_build_id($form) {
+  return array(
+    'command' => 'updateBuildId',
+    'old' => $form['#build_id_old'],
+    'new' => $form['#build_id'],
+  );
+}
+
+/**
+ * Creates a Drupal Ajax 'add_css' command.
+ *
+ * This method will add css via ajax in a cross-browser compatible way.
+ *
+ * This command is implemented by Drupal.ajax.prototype.commands.add_css()
+ * defined in misc/ajax.js.
+ *
+ * @param $styles
+ *   A string that contains the styles to be added.
+ *
+ * @return
+ *   An array suitable for use with the ajax_render() function.
+ *
+ * @see misc/ajax.js
+ */
+function ajax_command_add_css($styles) {
+  return array(
+    'command' => 'add_css',
+    'data' => $styles,
+  );
+}