drupal/core/modules/views/views.module

<?php

/**
 * @file
 * Primarily Drupal hooks and global API functions to manipulate views.
 *
 * This is the main module file for Views. The main entry points into
 * this module are views_page() and views_block(), where it handles
 * incoming page and block requests.
 */

use Drupal\Core\Database\Query\AlterableInterface;
use Drupal\views\ViewExecutable;
use Drupal\Component\Plugin\Exception\PluginException;
use Drupal\views\Plugin\Core\Entity\View;

/**
 * Implements hook_forms().
 *
 * To provide distinct form IDs for Views forms, the View name and
 * specific display name are appended to the base ID,
 * views_form_views_form. When such a form is built or submitted, this
 * function will return the proper callback function to use for the given form.
 */
function views_forms($form_id, $args) {
  if (strpos($form_id, 'views_form_') === 0) {
    return array(
      $form_id => array(
        'callback' => 'views_form',
      ),
    );
  }
}

/**
 * Returns a form ID for a Views form using the name and display of the View.
 */
function views_form_id($view) {
  $parts = array(
    'views_form',
    $view->storage->id(),
    $view->current_display,
  );

  return implode('_', $parts);
}

/**
 * Implements hook_element_info().
 */
function views_element_info() {
  $types['view'] = array(
    '#theme_wrappers' => array('container'),
    '#pre_render' => array('views_pre_render_view_element'),
    '#name' => NULL,
    '#display_id' => 'default',
    '#arguments' => array(),
  );
  return $types;
}

/**
 * View element pre render callback.
 */
function views_pre_render_view_element($element) {
  $element['#attributes']['class'][] = 'views-element-container';

  $view = views_get_view($element['#name']);
  if ($view && $view->access($element['#display_id'])) {
    $element['view']['#markup'] = $view->preview($element['#display_id'], $element['#arguments']);
  }

  return $element;
}

/**
 * Implement hook_theme(). Register views theming functions.
 */
function views_theme($existing, $type, $theme, $path) {
  module_load_include('inc', 'views', 'views.theme');

  // Some quasi clever array merging here.
  $base = array(
    'file' => 'views.theme.inc',
  );

  // Our extra version of pager from pager.inc
  $hooks['views_mini_pager'] = $base + array(
    'variables' => array('tags' => array(), 'quantity' => 10, 'element' => 0, 'parameters' => array()),
    'pattern' => 'views_mini_pager__',
  );

  $variables = array(
    // For displays, we pass in a dummy array as the first parameter, since
    // $view is an object but the core contextual_preprocess() function only
    // attaches contextual links when the primary theme argument is an array.
    'display' => array('view_array' => array(), 'view' => NULL),
    'style' => array('view' => NULL, 'options' => NULL, 'rows' => NULL, 'title' => NULL),
    'row' => array('view' => NULL, 'options' => NULL, 'row' => NULL, 'field_alias' => NULL),
    'exposed_form' => array('view' => NULL, 'options' => NULL),
    'pager' => array(
      'view' => NULL, 'options' => NULL,
      'tags' => array(), 'quantity' => 10, 'element' => 0, 'parameters' => array()
    ),
  );

  // Default view themes
  $hooks['views_view_field'] = $base + array(
    'pattern' => 'views_view_field__',
    'variables' => array('view' => NULL, 'field' => NULL, 'row' => NULL),
  );
  $hooks['views_view_grouping'] = $base + array(
    'pattern' => 'views_view_grouping__',
    'variables' => array('view' => NULL, 'grouping' => NULL, 'grouping_level' => NULL, 'rows' => NULL, 'title' => NULL),
  );

  $plugins = views_get_plugin_definitions();

  // Register theme functions for all style plugins
  foreach ($plugins as $type => $info) {
    foreach ($info as $plugin => $def) {
      // Not all plugins have theme functions, and they can also explicitly
      // prevent a theme function from being registered automatically.
      if (!isset($def['theme']) || empty($def['register_theme'])) {
        continue;
      }

      $hooks[$def['theme']] = array(
        'pattern' => $def['theme'] . '__',
        'variables' => $variables[$type],
      );

      if ($def['module'] == 'views') {
        $def['theme_file'] = 'views.theme.inc';
      }
      elseif (isset($def['theme_file'])) {
        $def['theme_path'] = drupal_get_path('module', $def['module']);
      }

      if (isset($def['theme_path'])) {
        $hooks[$def['theme']]['path'] = $def['theme_path'];
      }
      if (isset($def['theme_file'])) {
        $hooks[$def['theme']]['file'] = $def['theme_file'];
      }
      if (isset($def['theme_path']) && isset($def['theme_file'])) {
        $include = DRUPAL_ROOT . '/' . $def['theme_path'] . '/' . $def['theme_file'];
        if (is_file($include)) {
          require_once $include;
        }
      }
      if (!function_exists('theme_' . $def['theme'])) {
        $hooks[$def['theme']]['template'] = drupal_clean_css_identifier($def['theme']);
      }
    }
  }

  $hooks['views_form_views_form'] = $base + array(
    'render element' => 'form',
  );

  $hooks['views_exposed_form'] = $base + array(
    'template' => 'views-exposed-form',
    'pattern' => 'views_exposed_form__',
    'render element' => 'form',
  );

  $hooks['views_more'] = $base + array(
    'template' => 'views-more',
    'pattern' => 'views_more__',
    'variables' => array('more_url' => NULL, 'link_text' => 'more', 'view' => NULL),
  );

  return $hooks;
}

/**
 * Returns a list of plugins and metadata about them.
 *
 * @return array
 *   An array keyed by PLUGIN_TYPE:PLUGIN_NAME, like 'display:page' or
 *   'pager:full', containing an array with the following keys:
 *   - title: The plugin's title.
 *   - type: The plugin type.
 *   - module: The module providing the plugin.
 *   - views: An array of enabled Views that are currently using this plugin,
 *     keyed by machine name.
 */
function views_plugin_list() {
  $plugin_data = views_get_plugin_definitions();
  $plugins = array();
  foreach (views_get_enabled_views() as $view) {
    foreach ($view->get('display') as $display_id => $display) {
      foreach ($plugin_data as $type => $info) {
        if ($type == 'display' && isset($display['display_plugin'])) {
          $name = $display['display_plugin'];
        }
        elseif (isset($display['display_options']["{$type}_plugin"])) {
          $name = $display['display_options']["{$type}_plugin"];
        }
        elseif (isset($display['display_options'][$type]['type'])) {
          $name = $display['display_options'][$type]['type'];
        }
        else {
          continue;
        }

        // Key first by the plugin type, then the name.
        $key = $type . ':' . $name;
        // Add info for this plugin.
        if (!isset($plugins[$key])) {
          $plugins[$key] = array(
            'type' => $type,
            'title' => check_plain($info[$name]['title']),
            'module' => check_plain($info[$name]['module']),
            'views' => array(),
          );
        }

        // Add this view to the list for this plugin.
        $plugins[$key]['views'][$view->id()] = $view->id();
      }
    }
  }
  return $plugins;
}

/**
 * A theme preprocess function to automatically allow view-based node
 * templates if called from a view.
 *
 * The 'modules/node.views.inc' file is a better place for this, but
 * we haven't got a chance to load that file before Drupal builds the
 * node portion of the theme registry.
 */
function views_preprocess_node(&$vars) {
  // The 'view' attribute of the node is added in views_preprocess_node()
  if (!empty($vars['node']->view) && $vars['node']->view->storage->id()) {
    $vars['view'] = $vars['node']->view;
    $vars['theme_hook_suggestions'][] = 'node__view__' . $vars['node']->view->storage->id();
    if (!empty($vars['node']->view->current_display)) {
      $vars['theme_hook_suggestions'][] = 'node__view__' . $vars['node']->view->storage->id() . '__' . $vars['node']->view->current_display;

      // If a node is being rendered in a view, and the view does not have a path,
      // prevent drupal from accidentally setting the $page variable:
      if ($vars['page'] && $vars['view_mode'] == 'full' && !$vars['view']->display_handler->hasPath()) {
        $vars['page'] = FALSE;
      }
    }
  }

  // Allow to alter comments and links based on the settings in the row plugin.
  if (!empty($vars['view']->style_plugin->row_plugin) && get_class($vars['view']->style_plugin->row_plugin) == 'views_plugin_row_node_view') {
    node_row_node_view_preprocess_node($vars);
  }
}

/**
 * A theme preprocess function to automatically allow view-based node
 * templates if called from a view.
 */
function views_preprocess_comment(&$vars) {
  // The 'view' attribute of the node is added in template_preprocess_views_view_row_comment()
  if (!empty($vars['comment']->view) && $vars['comment']->view->storage->id()) {
    $vars['view'] = &$vars['comment']->view;
    $vars['theme_hook_suggestions'][] = 'comment__view__' . $vars['comment']->view->storage->id();
    if (!empty($vars['node']->view->current_display)) {
      $vars['theme_hook_suggestions'][] = 'comment__view__' . $vars['comment']->view->storage->id() . '__' . $vars['comment']->view->current_display;
    }
  }
}

/**
 * Implement hook_permission().
 */
function views_permission() {
  return array(
    'administer views' => array(
      'title' => t('Administer views'),
      'description' => t('Access the views administration pages.'),
    ),
    'access all views' => array(
      'title' => t('Bypass views access control'),
      'description' => t('Bypass access control when accessing views.'),
    ),
  );
}

/**
 * Implement hook_menu().
 */
function views_menu() {
  // Any event which causes a menu rebuild could potentially mean that the
  // Views data is updated -- module changes, profile changes, etc.
  views_invalidate_cache();
  $items = array();
  $items['views/ajax'] = array(
    'title' => 'Views',
    'page callback' => 'views_ajax',
    'theme callback' => 'ajax_base_page_theme',
    'delivery callback' => 'ajax_deliver',
    'access callback' => TRUE,
    'description' => 'Ajax callback for view loading.',
    'type' => MENU_CALLBACK,
    'file' => 'includes/ajax.inc',
  );
  // Define another taxonomy autocomplete because the default one of drupal
  // does not support a vid a argument anymore
  $items['admin/views/ajax/autocomplete/taxonomy/%'] = array(
    'page callback' => 'views_ajax_autocomplete_taxonomy',
    'theme callback' => 'ajax_base_page_theme',
    'access callback' => 'user_access',
    'access arguments' => array('access content'),
    'type' => MENU_CALLBACK,
    'file' => 'includes/ajax.inc',
  );
  return $items;
}

/**
 * Implement hook_menu_alter().
 */
function views_menu_alter(&$callbacks) {
  $our_paths = array();
  $views = views_get_applicable_views('uses_hook_menu');
  foreach ($views as $data) {
    list($view, $display_id) = $data;
    $result = $view->executeHookMenu($display_id, $callbacks);
    if (is_array($result)) {
      // The menu system doesn't support having two otherwise
      // identical paths with different placeholders.  So we
      // want to remove the existing items from the menu whose
      // paths would conflict with ours.

      // First, we must find any existing menu items that may
      // conflict.  We use a regular expression because we don't
      // know what placeholders they might use.  Note that we
      // first construct the regex itself by replacing %views_arg
      // in the display path, then we use this constructed regex
      // (which will be something like '#^(foo/%[^/]*/bar)$#') to
      // search through the existing paths.
      $regex = '#^(' . preg_replace('#%views_arg#', '%[^/]*', implode('|', array_keys($result))) . ')$#';
      $matches = preg_grep($regex, array_keys($callbacks));

      // Remove any conflicting items that were found.
      foreach ($matches as $path) {
        // Don't remove the paths we just added!
        if (!isset($our_paths[$path])) {
          unset($callbacks[$path]);
        }
      }
      foreach ($result as $path => $item) {
        if (!isset($callbacks[$path])) {
          // Add a new item, possibly replacing (and thus effectively
          // overriding) one that we removed above.
          $callbacks[$path] = $item;
        }
        else {
          // This item already exists, so it must be one that we added.
          // We change the various callback arguments to pass an array
          // of possible display IDs instead of a single ID.
          $callbacks[$path]['page arguments'][1] = (array)$callbacks[$path]['page arguments'][1];
          $callbacks[$path]['page arguments'][1][] = $display_id;
          $callbacks[$path]['access arguments'][] = $item['access arguments'][0];
          $callbacks[$path]['load arguments'][1] = (array)$callbacks[$path]['load arguments'][1];
          $callbacks[$path]['load arguments'][1][] = $display_id;
        }
        $our_paths[$path] = TRUE;
      }
    }
    $view->destroy();
  }
}

/**
 * Helper function for menu loading. This will automatically be
 * called in order to 'load' a views argument; primarily it
 * will be used to perform validation.
 *
 * @param $value
 *   The actual value passed.
 * @param $name
 *   The name of the view. This needs to be specified in the 'load function'
 *   of the menu entry.
 * @param $display_id
 *   The display id that will be loaded for this menu item.
 * @param $index
 *   The menu argument index. This counts from 1.
 */
function views_arg_load($value, $name, $display_id, $index) {
  static $views = array();

  // Make sure we haven't already loaded this views argument for a similar menu
  // item elsewhere.
  $key = $name . ':' . $display_id . ':' . $value . ':' . $index;
  if (isset($views[$key])) {
    return $views[$key];
  }

  if ($view = views_get_view($name)) {
    $view->setDisplay($display_id);
    $view->initHandlers();

    $ids = array_keys($view->argument);

    $indexes = array();
    $path = explode('/', $view->getPath());

    foreach ($path as $id => $piece) {
      if ($piece == '%' && !empty($ids)) {
        $indexes[$id] = array_shift($ids);
      }
    }

    if (isset($indexes[$index])) {
      if (isset($view->argument[$indexes[$index]])) {
        $arg = $view->argument[$indexes[$index]]->validate_argument($value) ? $value : FALSE;
        $view->destroy();

        // Store the output in case we load this same menu item again.
        $views[$key] = $arg;
        return $arg;
      }
    }
    $view->destroy();
  }
}

/**
 * Page callback: Displays a page view, given a name and display id.
 *
 * @param $name
 *   The name of a view.
 * @param $display_id
 *   The display id of a view.
 *
 * @return
 *   Either the HTML of a fully-executed view, or MENU_NOT_FOUND.
 */
function views_page($name, $display_id) {
  $args = func_get_args();
  // Remove $name and $display_id from the arguments.
  array_shift($args);
  array_shift($args);

  // Load the view and render it.
  if ($view = views_get_view($name)) {
    return $view->executeDisplay($display_id, $args);
  }

  // Fallback; if we get here no view was found or handler was not valid.
  return MENU_NOT_FOUND;
}

/**
 * Implements hook_page_alter().
 */
function views_page_alter(&$page) {
  // If the main content of this page contains a view, attach its contextual
  // links to the overall page array. This allows them to be rendered directly
  // next to the page title.
  if ($view = views_get_page_view()) {
    views_add_contextual_links($page, 'page', $view, $view->current_display);
  }
}

/**
 * Implements MODULE_preprocess_HOOK().
 */
function views_preprocess_html(&$variables) {
  // If the page contains a view as its main content, contextual links may have
  // been attached to the page as a whole; for example, by views_page_alter().
  // This allows them to be associated with the page and rendered by default
  // next to the page title (which we want). However, it also causes the
  // Contextual Links module to treat the wrapper for the entire page (i.e.,
  // the <body> tag) as the HTML element that these contextual links are
  // associated with. This we don't want; for better visual highlighting, we
  // prefer a smaller region to be chosen. The region we prefer differs from
  // theme to theme and depends on the details of the theme's markup in
  // page.tpl.php, so we can only find it using JavaScript. We therefore remove
  // the "contextual-region" class from the <body> tag here and add
  // JavaScript that will insert it back in the correct place.
  if (!empty($variables['page']['#views_contextual_links_info'])) {
    $key = array_search('contextual-region', $variables['attributes']['class']->value());
    if ($key !== FALSE) {
      unset($variables['attributes']['class'][$key]);
      // Add the JavaScript, with a group and weight such that it will run
      // before modules/contextual/contextual.js.
      drupal_add_js(drupal_get_path('module', 'views') . '/js/views-contextual.js', array('group' => JS_LIBRARY, 'weight' => -1));
    }
  }
}

/**
 * Implements hook_contextual_links_view_alter().
 */
function views_contextual_links_view_alter(&$element, $items) {
  // If we are rendering views-related contextual links attached to the overall
  // page array, add a class to the list of contextual links. This will be used
  // by the JavaScript added in views_preprocess_html().
  if (!empty($element['#element']['#views_contextual_links_info']) && !empty($element['#element']['#type']) && $element['#element']['#type'] == 'page') {
    $element['#attributes']['class'][] = 'views-contextual-links-page';
  }
}

/**
 * Converts Views block content to a renderable array with contextual links.
 *
 * @param $block
 *   An array representing the block, with the same structure as the return
 *   value of hook_block_view(). This will be modified so as to force
 *   $block['content'] to be a renderable array, containing the optional
 *   '#contextual_links' property (if there are any contextual links associated
 *   with the block).
 * @param $view
 *   The view that was used to generate the block content.
 * @param $display_id
 *   The ID of the display within the view that was used to generate the block
 *   content.
 * @param $block_type
 *   The type of the block. If it's block it's a regular views display,
 *   but 'special_block_-exp' exist as well.
 */
function views_add_block_contextual_links(&$block, ViewExecutable $view, $display_id, $block_type = 'block') {
  // Do not add contextual links to an empty block.
  if (!empty($block)) {
    // Contextual links only work on blocks whose content is a renderable
    // array, so if the block contains a string of already-rendered markup,
    // convert it to an array.
    if (is_string($block)) {
      $block = array('#markup' => $block);
    }
    // Add the contextual links.
    views_add_contextual_links($block, $block_type, $view, $display_id);
  }
}

/**
 * Adds contextual links associated with a view display to a renderable array.
 *
 * This function should be called when a view is being rendered in a particular
 * location and you want to attach the appropriate contextual links (e.g.,
 * links for editing the view) to it.
 *
 * The function operates by checking the view's display plugin to see if it has
 * defined any contextual links that are intended to be displayed in the
 * requested location; if so, it attaches them. The contextual links intended
 * for a particular location are defined by the 'contextual links' and
 * 'contextual_links_locations' properties in the plugin annotation; as a
 * result, these hook implementations have full control over where and how
 * contextual links are rendered for each display.
 *
 * In addition to attaching the contextual links to the passed-in array (via
 * the standard #contextual_links property), this function also attaches
 * additional information via the #views_contextual_links_info property. This
 * stores an array whose keys are the names of each module that provided
 * views-related contextual links (same as the keys of the #contextual_links
 * array itself) and whose values are themselves arrays whose keys ('location',
 * 'view_name', and 'view_display_id') store the location, name of the view,
 * and display ID that were passed in to this function. This allows you to
 * access information about the contextual links and how they were generated in
 * a variety of contexts where you might be manipulating the renderable array
 * later on (for example, alter hooks which run later during the same page
 * request).
 *
 * @param $render_element
 *   The renderable array to which contextual links will be added. This array
 *   should be suitable for passing in to drupal_render() and will normally
 *   contain a representation of the view display whose contextual links are
 *   being requested.
 * @param $location
 *   The location in which the calling function intends to render the view and
 *   its contextual links. The core system supports three options for this
 *   parameter:
 *   - 'block': Used when rendering a block which contains a view. This
 *     retrieves any contextual links intended to be attached to the block
 *     itself.
 *   - 'page': Used when rendering the main content of a page which contains a
 *     view. This retrieves any contextual links intended to be attached to the
 *     page itself (for example, links which are displayed directly next to the
 *     page title).
 *   - 'view': Used when rendering the view itself, in any context. This
 *     retrieves any contextual links intended to be attached directly to the
 *     view.
 *   If you are rendering a view and its contextual links in another location,
 *   you can pass in a different value for this parameter. However, you will
 *   also need to set 'contextual_links_locations' in your plugin annotation to
 *   indicate which view displays support having their contextual links
 *   rendered in the location you have defined.
 * @param $view
 *   The view whose contextual links will be added.
 * @param $display_id
 *   The ID of the display within $view whose contextual links will be added.
 *
 * @see views_block_view()
 * @see views_page_alter()
 * @see template_preprocess_views_view()
 */
function views_add_contextual_links(&$render_element, $location, ViewExecutable $view, $display_id) {
  // Do not do anything if the view is configured to hide its administrative
  // links.
  if (empty($view->hide_admin_links)) {
    // Also do not do anything if the display plugin has not defined any
    // contextual links that are intended to be displayed in the requested
    // location.
    $plugin_id = $view->displayHandlers->get($display_id)->getPluginId();
    $plugin = drupal_container()->get('plugin.manager.views.display')->getDefinition($plugin_id);
    // If contextual_links_locations are not set, provide a sane default. (To
    // avoid displaying any contextual links at all, a display plugin can still
    // set 'contextual_links_locations' to, e.g., {""}.)

    if (!isset($plugin['contextual_links_locations'])) {
      $plugin['contextual_links_locations'] = array('view');
    }
    elseif ($plugin['contextual_links_locations'] == array() || $plugin['contextual_links_locations'] == array('')) {
      $plugin['contextual_links_locations'] = array();
    }
    else {
      $plugin += array('contextual_links_locations' => array('view'));
    }

    // On exposed_forms blocks contextual links should always be visible.
    $plugin['contextual_links_locations'][] = 'special_block_-exp';
    $has_links = !empty($plugin['contextual links']) && !empty($plugin['contextual_links_locations']);
    if ($has_links && in_array($location, $plugin['contextual_links_locations'])) {
      foreach ($plugin['contextual links'] as $module => $link) {
        $args = array();
        $valid = TRUE;
        if (!empty($link['argument properties'])) {
          foreach ($link['argument properties'] as $property) {
            // If the plugin is trying to create an invalid contextual link
            // (for example, "path/to/{$view->storage->property}", where
            // $view->storage->{property} does not exist), we cannot construct
            // the link, so we skip it.
            if (!property_exists($view->storage, $property)) {
              $valid = FALSE;
              break;
            }
            else {
              $args[] = $view->storage->{$property};
            }
          }
        }
        // If the link was valid, attach information about it to the renderable
        // array.
        if ($valid) {
          $render_element['#contextual_links'][$module] = array($link['parent path'], $args);
          $render_element['#views_contextual_links_info'][$module] = array(
            'location' => $location,
            'view' => $view,
            'view_name' => $view->storage->id(),
            'view_display_id' => $display_id,
          );
        }
      }
    }
  }
}

/**
 * Prepares a list of language names.
 *
 * This is a wrapper around language_list to return a plain key value array.
 *
 * @param string $field
 *   The field of the language object which should be used as the value of the
 *   array.
 * @param int $flags
 *   (optional) Specifies the state of the languages that have to be returned.
 *   It can be: LANGUAGE_CONFIGURABLE, LANGUAGE_LOCKED, LANGUAGE_ALL.
 *
 * @return array
 *   An array of language names (or $field) keyed by the langcode.
 *
 * @see locale_language_list()
 */
function views_language_list($field = 'name', $flags = LANGUAGE_ALL) {
  $languages = language_list($flags);
  $list = array();
  foreach ($languages as $language) {
    $list[$language->langcode] = ($field == 'name') ? t($language->name) : $language->$field;
  }
  return $list;
}

/**
 * Implements hook_cache_flush().
 */
function views_cache_flush() {
  return array('views_info', 'views_results');
}

/**
 * Implements hook_field_create_instance.
 */
function views_field_create_instance($instance) {
  cache('views_info')->deleteAll();
  cache('views_results')->deleteAll();
}

/**
 * Implements hook_field_update_instance.
 */
function views_field_update_instance($instance, $prior_instance) {
  cache('views_info')->deleteAll();
  cache('views_results')->deleteAll();
}

/**
 * Implements hook_field_delete_instance.
 */
function views_field_delete_instance($instance) {
  cache('views_info')->deleteAll();
  cache('views_results')->deleteAll();
}

/**
 * Invalidate the views cache, forcing a rebuild on the next grab of table data.
 */
function views_invalidate_cache() {
  // Clear the views cache.
  cache('views_info')->deleteAll();

  // Clear the page and block cache.
  cache_delete_tags(array('content' => TRUE));

  // Set the menu as needed to be rebuilt.
  state()->set('menu_rebuild_needed', TRUE);

  // Invalidate the block cache to update views block derivatives.
  if (module_exists('block')) {
    drupal_container()->get('plugin.manager.block')->clearCachedDefinitions();
  }

  // Allow modules to respond to the Views cache being cleared.
  module_invoke_all('views_invalidate_cache');
}

/**
 * Access callback to determine if the user can import Views.
 *
 * View imports require an additional access check because they are PHP
 * code and PHP is more locked down than administer views.
 */
function views_import_access() {
  return user_access('administer views') && user_access('use PHP for settings');
}

/**
 * Determine if the logged in user has access to a view.
 *
 * This function should only be called from a menu hook or some other
 * embedded source. Each argument is the result of a call to
 * views_plugin_access::get_access_callback() which is then used
 * to determine if that display is accessible. If *any* argument
 * is accessible, then the view is accessible.
 */
function views_access() {
  $args = func_get_args();
  foreach ($args as $arg) {
    if ($arg === TRUE) {
      return TRUE;
    }

    if (!is_array($arg)) {
      continue;
    }

    list($callback, $arguments) = $arg;
    $arguments = $arguments ? $arguments : array();
    // Bring dynamic arguments to the access callback.
    foreach ($arguments as $key => $value) {
      if (is_int($value) && isset($args[$value])) {
        $arguments[$key] = $args[$value];
      }
    }
    if (function_exists($callback) && call_user_func_array($callback, $arguments)) {
      return TRUE;
    }
  }

  return FALSE;
}

/**
 * Access callback for the views_plugin_access_perm access plugin.
 *
 * Determine if the specified user has access to a view on the basis of
 * permissions. If the $account argument is omitted, the current user
 * is used.
 */
function views_check_perm($perm, $account = NULL) {
  return user_access($perm, $account) || user_access('access all views', $account);
}

/**
 * Access callback for the views_plugin_access_role access plugin.

 * Determine if the specified user has access to a view on the basis of any of
 * the requested roles. If the $account argument is omitted, the current user
 * is used.
 */
function views_check_roles($rids, $account = NULL) {
  global $user;
  $account = isset($account) ? $account : $user;
  $roles = array_keys($account->roles);
  $roles[] = $account->uid ? DRUPAL_AUTHENTICATED_RID : DRUPAL_ANONYMOUS_RID;
  return user_access('access all views', $account) || array_intersect(array_filter($rids), $roles);
}

/**
 * Set the current 'page view' that is being displayed so that it is easy
 * for other modules or the theme to identify.
 */
function &views_set_page_view($view = NULL) {
  static $cache = NULL;
  if (isset($view)) {
    $cache = $view;
  }

  return $cache;
}

/**
 * Find out what, if any, page view is currently in use. Please note that
 * this returns a reference, so be careful! You can unintentionally modify the
 * $view object.
 *
 * @return Drupal\views\ViewExecutable
 *   A fully formed, empty $view object.
 */
function &views_get_page_view() {
  return views_set_page_view();
}

/**
 * Set the current 'current view' that is being built/rendered so that it is
 * easy for other modules or items in drupal_eval to identify
 *
 * @return Drupal\views\ViewExecutable
 */
function &views_set_current_view($view = NULL) {
  static $cache = NULL;
  if (isset($view)) {
    $cache = $view;
  }

  return $cache;
}

/**
 * Find out what, if any, current view is currently in use. Please note that
 * this returns a reference, so be careful! You can unintentionally modify the
 * $view object.
 *
 * @return Drupal\views\ViewExecutable
 */
function &views_get_current_view() {
  return views_set_current_view();
}

/**
 * Include views .inc files as necessary.
 */
function views_include($file) {
  module_load_include('inc', 'views', 'includes/' . $file);
}

/**
 * Implements hook_hook_info().
 */
function views_hook_info() {
  $hooks['views_data'] = array(
    'group' => 'views',
  );
  $hooks['views_data_alter'] = array(
    'group' => 'views',
  );
  $hooks['views_query_substitutions'] = array(
    'group' => 'views',
  );
  $hooks['views_form_substitutions'] = array(
    'group' => 'views',
  );
  $hooks['views_analyze'] = array(
    'group' => 'views',
  );
  $hooks['views_data_alter'] = array(
    'group' => 'views',
  );

  return $hooks;
}

/**
 * Implements hook_library_info().
 */
function views_library_info() {
  $path = drupal_get_path('module', 'views') . '/js';
  $libraries['views.ajax'] = array(
    'title' => 'Views AJAX',
    'version' => VERSION,
    'js' => array(
      "$path/base.js" => array('group' => JS_DEFAULT),
      "$path/ajax_view.js" => array('group' => JS_DEFAULT),
    ),
    'dependencies' => array(
      array('system', 'jquery'),
      array('system', 'drupal'),
      array('system', 'drupalSettings'),
      array('system', 'jquery.once'),
      array('system', 'jquery.form'),
      array('system', 'drupal.ajax'),
    ),
  );

  return $libraries;
}

/**
 * Fetch a handler from the data cache.
 *
 * @param $table
 *   The name of the table this handler is from.
 * @param $field
 *   The name of the field this handler is from.
 * @param $type
 *   The type of handler. i.e, sort, field, argument, filter, relationship
 * @param $override
 *   Override the actual handler object with this class. Used for
 *   aggregation when the handler is redirected to the aggregation
 *   handler.
 *
 * @return views_handler
 *   An instance of a handler object. May be views_handler_broken.
 */
function views_get_handler($table, $field, $type, $override = NULL) {
  // Get the plugin manager for this type.
  $manager = drupal_container()->get("plugin.manager.views.$type");
  $data = drupal_container()->get('views.views_data')->get($table);

  if (isset($data[$field][$type])) {
    $definition = $data[$field][$type];
    foreach (array('group', 'title', 'title short', 'help', 'real field', 'real table') as $key) {
      if (!isset($definition[$key])) {
        // First check the field level
        if (!empty($data[$field][$key])) {
          $definition[$key] = $data[$field][$key];
        }
        // Then if that doesn't work, check the table level
        elseif (!empty($data['table'][$key])) {
          $definition[$key] = $data['table'][$key];
        }
      }
    }

    // @todo This is crazy. Find a way to remove the override functionality.
    $plugin_id = $override ?: $definition['id'];
    // Try to use the overridden handler.
    try {
      return $manager->createInstance($plugin_id, $definition);
    }
    catch (PluginException $e) {
      // If that fails, use the original handler.
      try {
        return $manager->createInstance($definition['id'], $definition);
      }
      catch (PluginException $e) {
        // Deliberately empty, this case is handled generically below.
      }
    }
  }

  // Finally, use the 'broken' handler.
  debug(t("Missing handler: @table @field @type", array('@table' => $table, '@field' => $field, '@type' => $type)));
  return $manager->createInstance('broken');
}

/**
 * Fetch a list of all base tables available
 *
 * @return array
 *   A keyed array of in the form of 'base_table' => 'Description'.
 */
function views_fetch_base_tables() {
  static $base_tables = array();
  if (empty($base_tables)) {
    $tables = array();
    $data = drupal_container()->get('views.views_data')->get();
    foreach ($data as $table => $info) {
      if (!empty($info['table']['base'])) {
        $tables[$table] = array(
          'title' => $info['table']['base']['title'],
          'description' => !empty($info['table']['base']['help']) ? $info['table']['base']['help'] : '',
          'weight' => !empty($info['table']['base']['weight']) ? $info['table']['base']['weight'] : 0,
        );
      }
    }
    uasort($tables, '_views_weight_sort');
    $base_tables = $tables;
  }

  return $base_tables;
}

/**
 * Sorts a structured array by the 'weight' and then by 'title' element.
 *
 * Callback for uasort() in views_fetch_base_tables().
 *
 * @param array $a
 *   First item for comparison. The compared items should be associative arrays
 *   that include a 'weight' and title element.
 * @param array $b
 *   Second item for comparison.
 *
 * @return int
 *   -1 if the first item comes first, 1 if second and 0 if they have the same
 *   order.
 */
function _views_weight_sort($a, $b) {
  if ($a['weight'] != $b['weight']) {
    return $a['weight'] < $b['weight'] ? -1 : 1;
  }
  if ($a['title'] != $b['title']) {
    return $a['title'] < $b['title'] ? -1 : 1;
  }

  return 0;
}

/**
 * Fetch a list of all base tables available
 *
 * @param $type
 *   Either 'display', 'style' or 'row'
 * @param $key
 *   For style plugins, this is an optional type to restrict to. May be 'normal',
 *   'summary', 'feed' or others based on the neds of the display.
 * @param $base
 *   An array of possible base tables.
 *
 * @return
 *   A keyed array of in the form of 'base_table' => 'Description'.
 */
function views_fetch_plugin_names($type, $key = NULL, $base = array()) {
  $definitions = drupal_container()->get("plugin.manager.views.$type")->getDefinitions();
  $plugins = array();

  foreach ($definitions as $id => $plugin) {
    // Skip plugins that don't conform to our key.
    if ($key && (empty($plugin['type']) || $plugin['type'] != $key)) {
      continue;
    }
    // @todo While Views is providing on behalf of core modules, check to see
    //   if they are enabled or not.
    if (isset($plugin['module']) && !module_exists($plugin['module'])) {
      continue;
    }

    if (empty($plugin['no_ui']) && (empty($base) || empty($plugin['base']) || array_intersect($base, $plugin['base']))) {
      $plugins[$id] = $plugin['title'];
    }
  }

  if (!empty($plugins)) {
    asort($plugins);
    return $plugins;
  }

  // fall-through
  return array();
}

/**
 * Gets all the views plugin definitions.
 *
 * @return array
 *   An array of plugin definitions for all types.
 */
function views_get_plugin_definitions() {
  $container = drupal_container();
  $plugins = array();
  foreach (ViewExecutable::getPluginTypes() as $plugin_type) {
    $plugins[$plugin_type] = $container->get("plugin.manager.views.$plugin_type")->getDefinitions();
  }

  return $plugins;
}

/**
 * Get enabled display extenders.
 */
function views_get_enabled_display_extenders() {
  $enabled = array_filter((array) config('views.settings')->get('display_extenders'));

  return drupal_map_assoc($enabled);
}

/**
 * Return a list of all views and display IDs that have a particular
 * setting in their display's plugin settings.
 *
 * @return
 * @code
 * array(
 *   array($view, $display_id),
 *   array($view, $display_id),
 * );
 * @endcode
 */
function views_get_applicable_views($type) {
  // @todo: Use a smarter flagging system so that we don't have to
  // load every view for this.
  $result = array();
  $views = views_get_all_views();

  foreach ($views as $view) {
    // Skip disabled views.
    if (!$view->isEnabled()) {
      continue;
    }

    $display = $view->get('display');
    if (empty($display)) {
      // Skip this view as it is broken.
      continue;
    }

    // Check each display to see if it meets the criteria and is enabled.
    $executable = $view->get('executable');
    $executable->setDisplay();
    foreach ($executable->displayHandlers as $id => $handler) {
      if (!empty($handler->definition[$type]) && $handler->isEnabled()) {
        $result[] = array($executable, $id);
      }
    }
  }
  return $result;
}

/**
 * Returns an array of all views as fully loaded $view objects.
 */
function views_get_all_views() {
  return drupal_container()->get('plugin.manager.entity')->getStorageController('view')->load();
}

/**
 * Returns an array of all enabled views, as fully loaded $view objects.
 */
function views_get_enabled_views() {
  $views = views_get_all_views();
  return array_filter($views, 'views_view_is_enabled');
}

/**
 * Returns an array of all disabled views, as fully loaded $view objects.
 */
function views_get_disabled_views() {
  $views = views_get_all_views();
  return array_filter($views, 'views_view_is_disabled');
}

/**
 * Return an array of view as options array, that can be used by select,
 * checkboxes and radios as #options.
 *
 * @param bool $views_only
 *  If TRUE, only return views, not displays.
 * @param string $filter
 *  Filters the views on status. Can either be 'all' (default), 'enabled' or
 *  'disabled'
 * @param  mixed $exclude_view
 *  view or current display to exclude
 *  either a
 *  - views object (containing $exclude_view->storage->name and $exclude_view->current_display)
 *  - views name as string:  e.g. my_view
 *  - views name and display id (separated by ':'): e.g. my_view:default
 * @param bool $optgroup
 *  If TRUE, returns an array with optgroups for each view (will be ignored for
 *  $views_only = TRUE). Can be used by select
 * @param bool $sort
 *  If TRUE, the list of views is sorted ascending.
 *
 * @return array
 *  an associative array for use in select.
 *  - key: view name and display id separated by ':', or the view name only
 */
function views_get_views_as_options($views_only = FALSE, $filter = 'all', $exclude_view = NULL, $optgroup = FALSE, $sort = FALSE) {

  // Filter the big views array.
  switch ($filter) {
    case 'all':
    case 'disabled':
    case 'enabled':
      $func = "views_get_{$filter}_views";
      $views = $func();
      break;
    default:
      return array();
  }

  // Prepare exclude view strings for comparison.
  if (empty($exclude_view)) {
    $exclude_view_name = '';
    $exclude_view_display = '';
  }
  elseif (is_object($exclude_view)) {
    $exclude_view_name = $exclude_view->storage->id();
    $exclude_view_display = $exclude_view->current_display;
  }
  else {
    // Append a ':' to the $exclude_view string so we always have more than one
    // item to explode.
    list($exclude_view_name, $exclude_view_display) = explode(':', "$exclude_view:");
  }

  $options = array();
  foreach ($views as $view) {
    $id = $view->id();
    // Return only views.
    if ($views_only && $id != $exclude_view_name) {
      $options[$id] = $view->getHumanName();
    }
    // Return views with display ids.
    else {
      foreach ($view->get('display') as $display_id => $display) {
        if (!($id == $exclude_view_name && $display_id == $exclude_view_display)) {
          if ($optgroup) {
            $options[$id][$id . ':' . $display['id']] = t('@view : @display', array('@view' => $id, '@display' => $display['id']));
          }
          else {
            $options[$id . ':' . $display['id']] = t('View: @view - Display: @display', array('@view' => $id, '@display' => $display['id']));
          }
        }
      }
    }
  }
  if ($sort) {
    ksort($options);
  }
  return $options;
}

/**
 * Returns whether the view is enabled.
 *
 * @param Drupal\views\Plugin\Core\Entity\View $view
 *   The view object to check.
 *
 * @return bool
 *   Returns TRUE if a view is enabled, FALSE otherwise.
 */
function views_view_is_enabled(View $view) {
  return $view->isEnabled();
}

/**
 * Returns whether the view is disabled.
 *
 * @param Drupal\views\Plugin\Core\Entity\View $view
 *   The view object to check.
 *
 * @return bool
 *   Returns TRUE if a view is disabled, FALSE otherwise.
 */
function views_view_is_disabled(View $view) {
  return !$view->isEnabled();
}

/**
 * Enables a view.
 *
 * @param Drupal\views\Plugin\Core\Entity\View $view
 *   The View object to disable.
 */
function views_enable_view(View $view) {
  $view->enable();
}

/**
 * Disables a view.
 *
 * @param Drupal\views\Plugin\Core\Entity\View $view
 *   The View object to disable.
 */
function views_disable_view(View $view) {
  $view->disable();
}

/**
 * Loads a view from configuration.
 *
 * @param string $name
 *   The name of the view.
 *
 * @return Drupal\views\ViewExecutable
 *   A reference to the $view object.
 */
function views_get_view($name) {
  $view = entity_load('view', $name);
  if ($view) {
    return $view->get('executable');
  }
}

/**
 * Returns TRUE if the passed-in view contains handlers with views form
 * implementations, FALSE otherwise.
 */
function views_view_has_form_elements($view) {
  foreach ($view->field as $field) {
    if (property_exists($field, 'views_form_callback') || method_exists($field, 'views_form')) {
      return TRUE;
    }
  }
  $area_handlers = array_merge(array_values($view->header), array_values($view->footer));
  $empty = empty($view->result);
  foreach ($area_handlers as $area) {
    if (method_exists($area, 'views_form') && !$area->views_form_empty($empty)) {
      return TRUE;
    }
  }
  return FALSE;
}

/**
 * This is the entry function. Just gets the form for the current step.
 * The form is always assumed to be multistep, even if it has only one
 * step (the default 'views_form_views_form' step). That way it is actually
 * possible for modules to have a multistep form if they need to.
 */
function views_form($form, &$form_state, ViewExecutable $view, $output) {
  $form_state['step'] = isset($form_state['step']) ? $form_state['step'] : 'views_form_views_form';
  // Cache the built form to prevent it from being rebuilt prior to validation
  // and submission, which could lead to data being processed incorrectly,
  // because the views rows (and thus, the form elements as well) have changed
  // in the meantime.
  $form_state['cache'] = TRUE;

  $form = array();
  $query = drupal_get_query_parameters();
  $form['#action'] = url($view->getUrl(), array('query' => $query));
  // Tell the preprocessor whether it should hide the header, footer, pager...
  $form['show_view_elements'] = array(
    '#type' => 'value',
    '#value' => ($form_state['step'] == 'views_form_views_form') ? TRUE : FALSE,
  );

  $form = $form_state['step']($form, $form_state, $view, $output);
  return $form;
}

/**
 * Callback for the main step of a Views form.
 * Invoked by views_form().
 */
function views_form_views_form($form, &$form_state, ViewExecutable $view, $output) {
  $form['#prefix'] = '<div class="views-form">';
  $form['#suffix'] = '</div>';
  $form['#theme'] = 'views_form_views_form';
  $form['#validate'][] = 'views_form_views_form_validate';
  $form['#submit'][] = 'views_form_views_form_submit';

  // Add the output markup to the form array so that it's included when the form
  // array is passed to the theme function.
  $form['output'] = array(
    '#type' => 'markup',
    '#markup' => $output,
    // This way any additional form elements will go before the view
    // (below the exposed widgets).
    '#weight' => 50,
  );

  $form['actions'] = array(
    '#type' => 'actions',
  );
  $form['actions']['submit'] = array(
    '#type' => 'submit',
    '#value' => t('Save'),
  );

  $substitutions = array();
  foreach ($view->field as $field_name => $field) {
    $form_element_name = $field_name;
    if (method_exists($field, 'form_element_name')) {
      $form_element_name = $field->form_element_name();
    }
    $method_form_element_row_id_exists = FALSE;
    if (method_exists($field, 'form_element_row_id')) {
      $method_form_element_row_id_exists = TRUE;
    }

    // If the field provides a views form, allow it to modify the $form array.
    $has_form = FALSE;
    if (property_exists($field, 'views_form_callback')) {
      $callback = $field->views_form_callback;
      $callback($view, $field, $form, $form_state);
      $has_form = TRUE;
    }
    elseif (method_exists($field, 'views_form')) {
      $field->views_form($form, $form_state);
      $has_form = TRUE;
    }

    // Build the substitutions array for use in the theme function.
    if ($has_form) {
      foreach ($view->result as $row_id => $row) {
        if ($method_form_element_row_id_exists) {
          $form_element_row_id = $field->form_element_row_id($row_id);
        }
        else {
          $form_element_row_id = $row_id;
        }

        $substitutions[] = array(
          'placeholder' => '<!--form-item-' . $form_element_name . '--' . $form_element_row_id . '-->',
          'field_name' => $form_element_name,
          'row_id' => $form_element_row_id,
        );
      }
    }
  }

  // Give the area handlers a chance to extend the form.
  $area_handlers = array_merge(array_values($view->header), array_values($view->footer));
  $empty = empty($view->result);
  foreach ($area_handlers as $area) {
    if (method_exists($area, 'views_form') && !$area->views_form_empty($empty)) {
      $area->views_form($form, $form_state);
    }
  }

  $form['#substitutions'] = array(
    '#type' => 'value',
    '#value' => $substitutions,
  );

  return $form;
}

/**
 * Validate handler for the first step of the views form.
 * Calls any existing views_form_validate functions located
 * on the views fields.
 */
function views_form_views_form_validate($form, &$form_state) {
  $view = $form_state['build_info']['args'][0];

  // Call the validation method on every field handler that has it.
  foreach ($view->field as $field_name => $field) {
    if (method_exists($field, 'views_form_validate')) {
      $field->views_form_validate($form, $form_state);
    }
  }

  // Call the validate method on every area handler that has it.
  foreach (array('header', 'footer') as $area) {
    foreach ($view->{$area} as $area_name => $area_handler) {
      if (method_exists($area_handler, 'views_form_validate')) {
        $area_handler->views_form_validate($form, $form_state);
      }
    }
  }
}

/**
 * Submit handler for the first step of the views form.
 * Calls any existing views_form_submit functions located
 * on the views fields.
 */
function views_form_views_form_submit($form, &$form_state) {
  $view = $form_state['build_info']['args'][0];

  // Call the submit method on every field handler that has it.
  foreach ($view->field as $field_name => $field) {
    if (method_exists($field, 'views_form_submit')) {
      $field->views_form_submit($form, $form_state);
    }
  }

  // Call the submit method on every area handler that has it.
  foreach (array('header', 'footer') as $area) {
    foreach ($view->{$area} as $area_name => $area_handler) {
      if (method_exists($area_handler, 'views_form_submit')) {
        $area_handler->views_form_submit($form, $form_state);
      }
    }
  }
}

/**
 * Form builder for the exposed widgets form.
 *
 * Be sure that $view and $display are references.
 */
function views_exposed_form($form, &$form_state) {
  // Don't show the form when batch operations are in progress.
  if ($batch = batch_get() && isset($batch['current_set'])) {
    return array(
      // Set the theme callback to be nothing to avoid errors in template_preprocess_views_exposed_form().
      '#theme' => '',
    );
  }

  // Make sure that we validate because this form might be submitted
  // multiple times per page.
  $form_state['must_validate'] = TRUE;
  $view = &$form_state['view'];
  $display = &$form_state['display'];

  $form_state['input'] = $view->getExposedInput();

  // Let form plugins know this is for exposed widgets.
  $form_state['exposed'] = TRUE;
  // Check if the form was already created
  if ($cache = views_exposed_form_cache($view->storage->id(), $view->current_display)) {
    return $cache;
  }

  $form['#info'] = array();

  // Go through each handler and let it generate its exposed widget.
  foreach ($view->display_handler->handlers as $type => $value) {
    foreach ($view->$type as $id => $handler) {
      if ($handler->canExpose() && $handler->isExposed()) {
        // Grouped exposed filters have their own forms.
        // Instead of render the standard exposed form, a new Select or
        // Radio form field is rendered with the available groups.
        // When an user choose an option the selected value is split
        // into the operator and value that the item represents.
        if ($handler->isAGroup()) {
          $handler->group_form($form, $form_state);
          $id = $handler->options['group_info']['identifier'];
        }
        else {
          $handler->buildExposedForm($form, $form_state);
        }
        if ($info = $handler->exposedInfo()) {
          $form['#info']["$type-$id"] = $info;
        }
      }
    }
  }

  $form['submit'] = array(
    // Prevent from showing up in $_GET.
    '#name' => '',
    '#type' => 'submit',
    '#value' => t('Apply'),
    '#id' => drupal_html_id('edit-submit-' . $view->storage->id()),
  );

  $form['#action'] = url($view->display_handler->getUrl());
  $form['#theme'] = views_theme_functions('views_exposed_form', $view, $display);
  $form['#id'] = drupal_clean_css_identifier('views_exposed_form-' . check_plain($view->storage->id()) . '-' . check_plain($display['id']));
//  $form['#attributes']['class'] = array('views-exposed-form');

  $exposed_form_plugin = $form_state['exposed_form_plugin'];
  $exposed_form_plugin->exposed_form_alter($form, $form_state);

  // Save the form
  views_exposed_form_cache($view->storage->id(), $view->current_display, $form);

  return $form;
}

/**
 * Implement hook_form_alter for the exposed form.
 *
 * Since the exposed form is a GET form, we don't want it to send a wide
 * variety of information.
 */
function views_form_views_exposed_form_alter(&$form, &$form_state) {
  $form['form_build_id']['#access'] = FALSE;
  $form['form_token']['#access'] = FALSE;
  $form['form_id']['#access'] = FALSE;
}

/**
 * Validate handler for exposed filters
 */
function views_exposed_form_validate(&$form, &$form_state) {
  foreach (array('field', 'filter') as $type) {
    $handlers = &$form_state['view']->$type;
    foreach ($handlers as $key => $handler) {
      $handlers[$key]->validateExposed($form, $form_state);
    }
  }
  $exposed_form_plugin = $form_state['exposed_form_plugin'];
  $exposed_form_plugin->exposed_form_validate($form, $form_state);
}

/**
 * Submit handler for exposed filters
 */
function views_exposed_form_submit(&$form, &$form_state) {
  foreach (array('field', 'filter') as $type) {
    $handlers = &$form_state['view']->$type;
    foreach ($handlers as $key => $info) {
      $handlers[$key]->submitExposed($form, $form_state);
    }
  }
  $form_state['view']->exposed_data = $form_state['values'];
  $form_state['view']->exposed_raw_input = array();

  $exclude = array('submit', 'form_build_id', 'form_id', 'form_token', 'exposed_form_plugin', '', 'reset');
  $exposed_form_plugin = $form_state['exposed_form_plugin'];
  $exposed_form_plugin->exposed_form_submit($form, $form_state, $exclude);

  foreach ($form_state['values'] as $key => $value) {
    if (!in_array($key, $exclude)) {
      $form_state['view']->exposed_raw_input[$key] = $value;
    }
  }
}

/**
 * Save the Views exposed form for later use.
 *
 * @param $views_name
 *   String. The views name.
 * @param $display_name
 *   String. The current view display name.
 * @param $form_output
 *   Array (optional). The form structure. Only needed when inserting the value.
 * @return
 *   Array. The form structure, if any. Otherwise, return FALSE.
 */
function views_exposed_form_cache($views_name, $display_name, $form_output = NULL) {
  // When running tests for exposed filters, this cache should
  // be cleared between each test.
  $views_exposed = &drupal_static(__FUNCTION__);

  // Save the form output
  if (!empty($form_output)) {
    $views_exposed[$views_name][$display_name] = $form_output;
    return;
  }

  // Return the form output, if any
  return empty($views_exposed[$views_name][$display_name]) ? FALSE : $views_exposed[$views_name][$display_name];
}

/**
 * Build a list of theme function names for use most everywhere.
 */
function views_theme_functions($hook, ViewExecutable $view, $display = NULL) {
  module_load_include('inc', 'views', 'views.theme');
  return _views_theme_functions($hook, $view, $display);
}

/**
 * Substitute current time; this works with cached queries.
 */
function views_views_query_substitutions($view) {
  return array(
    '***CURRENT_VERSION***' => VERSION,
    '***CURRENT_TIME***' => REQUEST_TIME,
    '***CURRENT_LANGUAGE***' => language(LANGUAGE_TYPE_CONTENT)->langcode,
    '***DEFAULT_LANGUAGE***' => language_default()->langcode,
  );
}

/**
 * Implements hook_query_TAG_alter().
 *
 * This is the hook_query_alter() for queries tagged by Views and is used to
 * add in substitutions from hook_views_query_substitutions().
 */
function views_query_views_alter(AlterableInterface $query) {
  $substitutions = $query->getMetaData('views_substitutions');
  $tables =& $query->getTables();
  $where =& $query->conditions();

  // Replaces substitions in tables.
  foreach ($tables as $table_name => $table_metadata) {
    foreach ($table_metadata['arguments'] as $replacement_key => $value) {
      if (isset($substitutions[$value])) {
        $tables[$table_name]['arguments'][$replacement_key] = $substitutions[$value];
      }
    }
  }

  // Replaces substitions in filter criterias.
  _views_query_tag_alter_condition($query, $where, $substitutions);
}

/**
 * Replaces the substitutions recursive foreach condition.
 */
function _views_query_tag_alter_condition(AlterableInterface $query, &$conditions, $substitutions) {
  foreach ($conditions as $condition_id => &$condition) {
    if (is_numeric($condition_id)) {
      if (is_string($condition['field'])) {
        $condition['field'] = str_replace(array_keys($substitutions), array_values($substitutions), $condition['field']);
      }
      elseif (is_object($condition['field'])) {
        $sub_conditions =& $condition['field']->conditions();
        _views_query_tag_alter_condition($query, $sub_conditions, $substitutions);
      }
      // $condition['value'] is a subquery so alter the subquery recursive.
      // Therefore take sure to get the metadata of the main query.
      if (is_object($condition['value'])) {
        $subquery = $condition['value'];
        $subquery->addMetaData('views_substitutions', $query->getMetaData('views_substitutions'));
        views_query_views_alter($condition['value']);
      }
      elseif (isset($condition['value'])) {
        $condition['value'] = str_replace(array_keys($substitutions), array_values($substitutions), $condition['value']);
      }
    }
  }
}

/**
 * Embed a view using a PHP snippet.
 *
 * This function is meant to be called from PHP snippets, should one wish to
 * embed a view in a node or something. It's meant to provide the simplest
 * solution and doesn't really offer a lot of options, but breaking the function
 * apart is pretty easy, and this provides a worthwhile guide to doing so.
 *
 * Note that this function does NOT display the title of the view. If you want
 * to do that, you will need to do what this function does manually, by
 * loading the view, getting the preview and then getting $view->getTitle().
 *
 * @param $name
 *   The name of the view to embed.
 * @param $display_id
 *   The display id to embed. If unsure, use 'default', as it will always be
 *   valid. But things like 'page' or 'block' should work here.
 * @param ...
 *   Any additional parameters will be passed as arguments.
 */
function views_embed_view($name, $display_id = 'default') {
  $args = func_get_args();
  array_shift($args); // remove $name
  if (count($args)) {
    array_shift($args); // remove $display_id
  }

  $view = views_get_view($name);
  if (!$view || !$view->access($display_id)) {
    return;
  }

  return $view->preview($display_id, $args);
}

/**
 * Get the result of a view.
 *
 * @param string $name
 *   The name of the view to retrieve the data from.
 * @param string $display_id
 *   The display id. On the edit page for the view in question, you'll find
 *   a list of displays at the left side of the control area. "Master"
 *   will be at the top of that list. Hover your cursor over the name of the
 *   display you want to use. An URL will appear in the status bar of your
 *   browser. This is usually at the bottom of the window, in the chrome.
 *   Everything after #views-tab- is the display ID, e.g. page_1.
 * @param ...
 *   Any additional parameters will be passed as arguments.
 * @return array
 *   An array containing an object for each view item.
 */
function views_get_view_result($name, $display_id = NULL) {
  $args = func_get_args();
  array_shift($args); // remove $name
  if (count($args)) {
    array_shift($args); // remove $display_id
  }

  $view = views_get_view($name);
  if (is_object($view)) {
    if (is_array($args)) {
      $view->setArguments($args);
    }
    if (is_string($display_id)) {
      $view->setDisplay($display_id);
    }
    else {
      $view->initDisplay();
    }
    $view->preExecute();
    $view->execute();
    return $view->result;
  }
  else {
    return array();
  }
}

/**
 * #process callback to see if we need to check_plain() the options.
 *
 * Since FAPI is inconsistent, the #options are sanitized for you in all cases
 * _except_ checkboxes. We have form elements that are sometimes 'select' and
 * sometimes 'checkboxes', so we need decide late in the form rendering cycle
 * if the options need to be sanitized before they're rendered. This callback
 * inspects the type, and if it's still 'checkboxes', does the sanitation.
 */
function views_process_check_options($element, &$form_state) {
  if ($element['#type'] == 'checkboxes' || $element['#type'] == 'checkbox') {
    $element['#options'] = array_map('check_plain', $element['#options']);
  }
  return $element;
}

/**
 * Validation callback for query tags.
 */
function views_element_validate_tags($element, &$form_state) {
  $values = array_map('trim', explode(',', $element['#value']));
  foreach ($values as $value) {
    if (preg_match("/[^a-z_]/", $value)) {
      form_error($element, t('The query tags may only contain lower-case alphabetical characters and underscores.'));
      return;
    }
  }
}

/**
 * Prerender function to move the textarea to the top.
 */
function views_handler_field_custom_pre_render_move_text($form) {
  $form['text'] = $form['alter']['text'];
  $form['help'] = $form['alter']['help'];
  unset($form['alter']['text']);
  unset($form['alter']['help']);

  return $form;
}

/**
 * Helper function: Return an array of formatter options for a field type.
 *
 * Borrowed from field_ui.
 */
function _field_view_formatter_options($field_type = NULL) {
  $options = &drupal_static(__FUNCTION__);

  if (!isset($options)) {
    $field_types = field_info_field_types();
    $options = array();
    foreach (field_info_formatter_types() as $name => $formatter) {
      foreach ($formatter['field_types'] as $formatter_field_type) {
        // Check that the field type exists.
        if (isset($field_types[$formatter_field_type])) {
          $options[$formatter_field_type][$name] = $formatter['label'];
        }
      }
    }
  }

  if ($field_type) {
    return !empty($options[$field_type]) ? $options[$field_type] : array();
  }
  return $options;
}

/**
 * Trim the field down to the specified length.
 *
 * @param $alter
 *   - max_length: Maximum lenght of the string, the rest gets truncated.
 *   - word_boundary: Trim only on a word boundary.
 *   - ellipsis: Show an ellipsis (...) at the end of the trimmed string.
 *   - html: Take sure that the html is correct.
 *
 * @param $value
 *   The string which should be trimmed.
 */
function views_trim_text($alter, $value) {
  if (drupal_strlen($value) > $alter['max_length']) {
    $value = drupal_substr($value, 0, $alter['max_length']);
    if (!empty($alter['word_boundary'])) {
      $regex = "(.*)\b.+";
      if (function_exists('mb_ereg')) {
        mb_regex_encoding('UTF-8');
        $found = mb_ereg($regex, $value, $matches);
      }
      else {
        $found = preg_match("/$regex/us", $value, $matches);
      }
      if ($found) {
        $value = $matches[1];
      }
    }
    // Remove scraps of HTML entities from the end of a strings
    $value = rtrim(preg_replace('/(?:<(?!.+>)|&(?!.+;)).*$/us', '', $value));

    if (!empty($alter['ellipsis'])) {
      // @todo: What about changing this to a real ellipsis?
      $value .= t('...');
    }
  }
  if (!empty($alter['html'])) {
    $value = _filter_htmlcorrector($value);
  }

  return $value;
}

/**
 * Filter by no empty values, though allow to use "0".
 * @param $var
 * @return bool
 */
function _views_array_filter_zero($var) {
  return trim($var) != "";
}

/**
 * Adds one to each key of the array.
 *
 * For example array(0 => 'foo') would be array(1 => 'foo').
 */
function views_array_key_plus($array) {
  $keys = array_keys($array);
  rsort($keys);
  foreach ($keys as $key) {
    $array[$key+1] = $array[$key];
    unset($array[$key]);
  }
  asort($array);
  return $array;
}

/**
 * Set a cached item in the views cache.
 *
 * This is just a convenience wrapper around cache_set().
 *
 * @param $cid
 *   The cache ID of the data to store.
 * @param $data
 *   The data to store in the cache. Complex data types will be automatically serialized before insertion.
 *   Strings will be stored as plain text and not serialized.
 * @param $use_language
 *   If TRUE, the data will be cached specific to the currently active language.
 */
function views_cache_set($cid, $data, $use_language = FALSE) {
  if (config('views.settings')->get('skip_cache')) {
    return;
  }
  if ($use_language) {
    $cid .= ':' . language(LANGUAGE_TYPE_INTERFACE)->langcode;
  }

  cache('views_info')->set($cid, $data);
}

/**
 * Return data from the persistent views cache.
 *
 * This is just a convenience wrapper around cache_get().
 *
 * @param int $cid
 *   The cache ID of the data to retrieve.
 * @param bool $use_language
 *   If TRUE, the data will be requested specific to the currently active language.
 *
 * @return stdClass|bool
 *   The cache or FALSE on failure.
 */
function views_cache_get($cid, $use_language = FALSE) {
  if (config('views.settings')->get('skip_cache')) {
    return FALSE;
  }
  if ($use_language) {
    $cid .= ':' . language(LANGUAGE_TYPE_INTERFACE)->langcode;
  }

  return cache('views_info')->get($cid);
}