layout.module | Documentation

The Layout module creates pages and wraps existing pages in layouts.
Backdrop's primary tool for positioning content is through layouts and blocks. A "layout" is the template that defines regions in which pieces of content may be placed. Each piece of content in this case is called a "block". Blocks may be placed multiple times in a single layout, and each block maintains separate settings. Each layout created saves to a configuration file, including all the settings for the blocks contained within it.
Layout module provides two distinct ways of rendering pages. It is capable of creating a stand-alone page that is created at any custom path specified by the user, and it can also "wrap" the content of any path provided by a module. In the case where a custom path is created, Layout module registers the path in the menu system through hook_menu(). For wrapping module-provided pages, Layout module declares itself as the system-wide "route handler", as checked in menu_execute_active_handler(). Layout module then becomes responsible for calling the module-provided content as a block, and positions other blocks around the existing content.
File

core/modules/layout/layout.module
View source
<?php
/**
 * @file
 * The Layout module creates pages and wraps existing pages in layouts.
 *
 * Backdrop's primary tool for positioning content is through layouts and
 * blocks. A "layout" is the template that defines regions in which pieces of
 * content may be placed. Each piece of content in this case is called a
 * "block". Blocks may be placed multiple times in a single layout, and each
 * block maintains separate settings. Each layout created saves to a
 * configuration file, including all the settings for the blocks contained
 * within it.
 *
 * Layout module provides two distinct ways of rendering pages. It is capable of
 * creating a stand-alone page that is created at any custom path specified by
 * the user, and it can also "wrap" the content of any path provided by a
 * module. In the case where a custom path is created, Layout module registers
 * the path in the menu system through hook_menu(). For wrapping module-provided
 * pages, Layout module declares itself as the system-wide "route handler", as
 * checked in menu_execute_active_handler(). Layout module then becomes
 * responsible for calling the module-provided content as a block, and positions
 * other blocks around the existing content.
 */

/**
 * Layouts constant for user-defined layouts.
 */
define('LAYOUT_STORAGE_NORMAL', 1);

/**
 * Layout constant for layouts that override module-defined presets.
 */
define('LAYOUT_STORAGE_OVERRIDE', 2);

/**
 * Layout constant for module-defined layouts.
 */
define('LAYOUT_STORAGE_DEFAULT', 4);

/**
 * Layout constant indicating the title of the layout is the default.
 */
define('LAYOUT_TITLE_DEFAULT', 'default');

/**
 * Layout constant indicating the title of the layout is not shown.
 */
define('LAYOUT_TITLE_NONE', 'none');

/**
 * Layout constant indicating the title of the layout is manually specified.
 */
define('LAYOUT_TITLE_CUSTOM', 'custom');

/**
 * Layout constant indicating the title of the layout comes from a block.
 */
define('LAYOUT_TITLE_BLOCK', 'block');

/**
 * Denotes that the block is disabled.
 */
define('BLOCK_DISABLED', 0);

/**
 * Denotes that the block is enabled.
 */
define('BLOCK_ENABLED', 1);

/**
 * Implements hook_menu().
 */
function layout_menu() {
  $items = array();

  $base = array(
    'access arguments' => array('administer layouts'),
    'theme callback' => 'ajax_base_page_theme',
  );

  $items['admin/structure/layouts'] = array(
    'title' => 'Layouts',
    'description' => 'Create new landing pages or modify the layout of existing pages on your site.',
    'page callback' => 'layout_list_page',
    'type' => MENU_NORMAL_ITEM,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts'] += $base;

  $items['admin/structure/layouts/list'] = array(
    'title' => 'List layouts',
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => -10,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/list'] += $base;

  $items['admin/structure/layouts/settings'] = array(
    'title' => 'Layout templates',
    'description' => 'Manage layout templates.',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_settings_page'),
    'type' => MENU_LOCAL_TASK,
    'weight' => 20,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/settings'] += $base;

  $items['admin/structure/layouts/settings/flexible-template/add'] = array(
    'title' => 'Add flexible layout template',
    'page callback' => 'layout_flexible_template_settings_add_form',
    'access arguments' => array('administer flexible templates'),
    'type' => MENU_LOCAL_ACTION,
    'weight' => -10,
    'file' => 'layout.flexible.inc',
  );
  $items['admin/structure/layouts/settings/flexible-template/add'] += $base;

  $items['admin/structure/layouts/settings/flexible-template/%layout_flexible_tempstore/edit'] = array(
    'title' => 'Configure flexible layout template',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_flexible_template_settings_edit_form', 5),
    'access arguments' => array('administer flexible templates'),
    'type' => MENU_NORMAL_ITEM,
    'weight' => -10,
    'file' => 'layout.flexible.inc',
  );
  $items['admin/structure/layouts/settings/flexible-template/%layout_flexible_tempstore/edit'] += $base;

  $items['admin/structure/layouts/settings/flexible-template/%layout_flexible_tempstore/configure'] = array(
    'title' => 'Configure flexible layout template',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_flexible_template_configure_form', 5),
    'access arguments' => array('administer flexible templates'),
    'type' => MENU_NORMAL_ITEM,
    'weight' => -10,
    'file' => 'layout.flexible.inc',
  );
  $items['admin/structure/layouts/settings/flexible-template/%layout_flexible_tempstore/configure'] += $base;

  $items['admin/structure/layouts/settings/flexible-template/%layout_flexible_tempstore/delete'] = array(
    'title' => 'Delete flexible layout template',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_flexible_template_delete_form', 5),
    'access arguments' => array('administer flexible templates'),
    'type' => MENU_NORMAL_ITEM,
    'weight' => -10,
    'file' => 'layout.flexible.inc',
  );
  $items['admin/structure/layouts/settings/flexible-template/%layout_flexible_tempstore/delete'] += $base;

  $items['admin/structure/layouts/settings/flexible-template/%layout_flexible_tempstore/row/%/delete'] = array(
    'title' => 'Delete row',
    'page callback' => 'layout_flexible_template_delete_row',
    'page arguments' => array(5, 7),
    'access arguments' => array('administer flexible templates'),
    'type' => MENU_CALLBACK,
    'weight' => -10,
    'file' => 'layout.flexible.inc',
  );
  $items['admin/structure/layouts/settings/flexible-template/%layout_flexible_tempstore/row/%/delete'] += $base;

  $items['admin/structure/layouts/settings/flexible-template/%layout_flexible_tempstore/row/%/select-widths'] = array(
    'title' => 'Choose region widths',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_flexible_template_region_style_select', 5, 7),
    'access arguments' => array('administer flexible templates'),
    'type' => MENU_CALLBACK,
    'weight' => -10,
    'file' => 'layout.flexible.inc',
  );
  $items['admin/structure/layouts/settings/flexible-template/%layout_flexible_tempstore/row/%/select-widths'] += $base;

  $items['admin/structure/layouts/settings/flexible-template/%layout_flexible_tempstore/row/%/configure'] = array(
    'title' => 'Add row',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_flexible_template_edit_row_form', 5, 7),
    'access arguments' => array('administer flexible templates'),
    'type' => MENU_CALLBACK,
    'weight' => -10,
    'file' => 'layout.flexible.inc',
  );
  $items['admin/structure/layouts/settings/flexible-template/%layout_flexible_tempstore/row/%/configure'] += $base;

  $items['admin/structure/layouts/settings/flexible-template/%layout_flexible_tempstore/row/%/configure/%'] = array(
    'title' => 'Add row',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_flexible_template_edit_row_form', 5, 7, 9),
    'access arguments' => array('administer flexible templates'),
    'type' => MENU_CALLBACK,
    'weight' => -10,
    'file' => 'layout.flexible.inc',
  );
  $items['admin/structure/layouts/settings/flexible-template/%layout_flexible_tempstore/row/%/configure/%'] += $base;

  $items['admin/structure/layouts/settings/toggle/%/enable'] = array(
    'title' => 'Enable layout template',
    'page callback' => 'layout_template_toggle_enabled',
    'page arguments' => array(5, TRUE),
    'type' => MENU_CALLBACK,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/settings/toggle/%/enable'] += $base;

  $items['admin/structure/layouts/settings/toggle/%/disable'] = array(
    'title' => 'Disable layout template',
    'page callback' => 'layout_template_toggle_enabled',
    'page arguments' => array(5, FALSE),
    'type' => MENU_CALLBACK,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/settings/toggle/%/disable'] += $base;

  $items['admin/structure/layouts/reorder'] = array(
    'title' => 'Reorder',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_reorder_form'),
    'type' => MENU_CALLBACK,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/reorder'] += $base;

  $items['admin/structure/layouts/add'] = array(
    'title' => 'Add layout',
    'page callback' => 'layout_add_page',
    'page arguments' => array(),
    'type' => MENU_LOCAL_ACTION,
    'weight' => -10,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/add'] += $base;

  $items['admin/structure/layouts/manage/%layout_tempstore'] = array(
    'title' => 'Manage blocks',
    'title callback' => 'layout_page_title',
    'title arguments' => array(4),
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_content_form', 4),
    'type' => MENU_NORMAL_ITEM,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore'] += $base;

  // @deprecated: Remove backwards-compatibility redirect in 2.0.
  $items['admin/structure/layouts/manage/%layout_tempstore/edit'] = array(
    'page callback' => 'system_redirect_deprecated_page',
    'page arguments' => array('admin/structure/layouts/manage/%layout_tempstore/blocks'),
    'access arguments' => array('administer layouts'),
    'type' => MENU_CALLBACK,
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/blocks'] = array(
    'title' => 'Manage blocks',
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => 0,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/blocks'] += $base;

  // @deprecated: Remove backwards-compatibility redirect in 2.0.
  $items['admin/structure/layouts/manage/%layout_tempstore/settings'] = array(
    'page callback' => 'system_redirect_deprecated_page',
    'page arguments' => array('admin/structure/layouts/manage/%layout_tempstore/configure'),
    'access arguments' => array('administer layouts'),
    'type' => MENU_CALLBACK,
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/configure'] = array(
    'title' => 'Configure layout',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_settings_form', 4),
    'type' => MENU_LOCAL_TASK,
    'weight' => 10,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/configure'] += $base;

  $items['admin/structure/layouts/manage/%layout_tempstore/add-block/%/%'] = array(
    'title' => 'Add block',
    'page callback' => 'layout_block_add_page',
    'page arguments' => array(4, 6, 7),
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/add-block/%/%'] += $base;

  $items['admin/structure/layouts/manage/%layout_tempstore/configure-region/%/%'] = array(
    'title' => 'Configure region',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_configure_region_page', 4, 6, 7),
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/configure-region/%/%'] += $base;

  $items['admin/structure/layouts/manage/%layout_tempstore/edit-title/editor/title'] = array(
    'title' => 'Configure page title',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_title_settings_form', 4),
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/edit-title/editor/title'] += $base;

  $items['admin/structure/layouts/manage/%layout_tempstore/configure-block/%/%layout_tempstore_block'] = array(
    'title' => 'Configure block',
    'load arguments' => array(4),
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_block_configure_form', 4, 7, 6),
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/configure-block/%/%layout_tempstore_block'] += $base;

  // This shortcut path does not use layout_tempstore, for efficiency when
  // checking access to this path from contextual links. To work as a contextual
  // link, we have to specify the context and also set the type to be a
  // MENU_LOCAL_TASK, even though this page never shows up as a tab anywhere.
  $items['admin/structure/layouts/manage/%layout/configure-redirect/%'] = array(
    'title' => 'Configure block',
    'load arguments' => array(4),
    'page callback' => 'layout_block_configure_redirect',
    'page arguments' => array(4, 6),
    'context' => MENU_CONTEXT_INLINE,
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout/configure-redirect/%'] += $base;

  $items['admin/structure/layouts/manage/%layout_tempstore/remove-block/%/%layout_tempstore_block'] = array(
    'title' => 'Remove block',
    'load arguments' => array(4),
    'page callback' => 'layout_block_remove_page',
    'page arguments' => array(4, 7, 6),
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/remove-block/%/%layout_tempstore_block'] += $base;

  $items['admin/structure/layouts/manage/%layout_tempstore/toggle-block-status/%/%layout_tempstore_block'] = array(
    'title' => 'Disable block',
    'load arguments' => array(4),
    'page callback' => 'layout_block_disable_page',
    'page arguments' => array(4, 7, 6),
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/toggle-block-status/%/%layout_tempstore_block'] += $base;

  $items['admin/structure/layouts/manage/%layout_tempstore/clone'] = array(
    'title' => 'Clone layout',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_clone_form', 4),
    'type' => MENU_CALLBACK,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/clone'] += $base;

  $items['admin/structure/layouts/manage/%layout_tempstore/enable'] = array(
    'page callback' => 'layout_toggle_enabled',
    'page arguments' => array(4, TRUE),
    'type' => MENU_CALLBACK,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/enable'] += $base;

  $items['admin/structure/layouts/manage/%layout_tempstore/disable'] = array(
    'page callback' => 'layout_toggle_enabled',
    'page arguments' => array(4, FALSE),
    'type' => MENU_CALLBACK,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/disable'] += $base;

  $items['admin/structure/layouts/manage/%layout_tempstore/delete'] = array(
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_delete_form', 4),
    'type' => MENU_CALLBACK,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/delete'] += $base;

  $items['admin/structure/layouts/manage/%layout_tempstore/break-lock'] = array(
    'page callback' => 'layout_break_lock_page',
    'page arguments' => array(4, 'layout'),
    'type' => MENU_CALLBACK,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/break-lock'] += $base;

  $items['admin/structure/layouts/manage/%layout_tempstore/context/add'] = array(
    'title' => 'Add context',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_context_add_form', 4),
    'type' => MENU_CALLBACK,
    'file' => 'layout.context.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/context/add'] += $base;

  $items['admin/structure/layouts/manage/%layout_tempstore/relationship/add'] = array(
    'title' => 'Add relationship',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_context_relationship_add_form', 4),
    'type' => MENU_CALLBACK,
    'file' => 'layout.context.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/relationship/add'] += $base;

  $items['admin/structure/layouts/manage/%layout_tempstore/context/edit/layout/%'] = array(
    'title' => 'Configure context',
    'load arguments' => array(4),
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_context_add_form', 4, 8),
    'type' => MENU_CALLBACK,
    'file' => 'layout.context.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/context/edit/layout/%'] += $base;

  $items['admin/structure/layouts/manage/%layout_tempstore/relationship/edit/layout/%'] = array(
    'title' => 'Configure relationship',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_context_relationship_add_form', 4, 8),
    'type' => MENU_CALLBACK,
    'file' => 'layout.context.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/relationship/edit/layout/%'] += $base;

  $items['admin/structure/layouts/manage/%layout_tempstore/condition/add'] = array(
    'title' => 'Add visibility condition',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_condition_add_form', 4),
    'type' => MENU_CALLBACK,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/condition/add'] += $base;

  $items['admin/structure/layouts/manage/%layout_tempstore/condition/edit/layout/%'] = array(
    'title' => 'Configure condition',
    'load arguments' => array(4),
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_condition_add_form', 4, NULL, NULL, 8),
    'type' => MENU_CALLBACK,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/condition/edit/layout/%'] += $base;

  $items['admin/structure/layouts/manage/%layout_tempstore/condition/add/%layout_tempstore_block'] = array(
    'title' => 'Add visibility condition',
    'load arguments' => array(4),
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_condition_add_form', 4, 7),
    'type' => MENU_CALLBACK,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/condition/add/%layout_tempstore_block'] += $base;

  $items['admin/structure/layouts/manage/%layout_tempstore/condition/edit/%layout_tempstore_block/%'] = array(
    'title' => 'Configure condition',
    'load arguments' => array(4),
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_condition_add_form', 4, 7, NULL, 8),
    'type' => MENU_CALLBACK,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/manage/%layout_tempstore/condition/edit/%layout_tempstore_block/%'] += $base;

  $items['admin/structure/layouts/menu/%layout_tempstore_menu_item'] = array(
    'title' => 'Menu settings',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_menu_item_form', 4),
    'type' => MENU_NORMAL_ITEM,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/menu/%layout_tempstore_menu_item'] += $base;

  $items['admin/structure/layouts/menu/%layout_tempstore_menu_item/settings'] = array(
    'title' => 'Menu settings',
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => -1,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/menu/%layout_tempstore_menu_item/settings'] += $base;

  $items['admin/structure/layouts/menu/%layout_tempstore_menu_item/break-lock'] = array(
    'page callback' => 'layout_break_lock_page',
    'page arguments' => array(4, 'menu_item'),
    'type' => MENU_CALLBACK,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/menu/%layout_tempstore_menu_item/break-lock'] += $base;

  $items['admin/structure/layouts/menu/%layout_tempstore_menu_item/condition/add'] = array(
    'title' => 'Add visibility condition',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_condition_add_form', NULL, NULL, 4),
    'type' => MENU_CALLBACK,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/menu/%layout_tempstore_menu_item/condition/add'] += $base;

  $items['admin/structure/layouts/menu/%layout_tempstore_menu_item/condition/edit/%'] = array(
    'title' => 'Configure condition',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('layout_condition_add_form', NULL, NULL, 4, 7),
    'type' => MENU_CALLBACK,
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/layouts/menu/%layout_tempstore_menu_item/condition/edit/%'] += $base;

  // Add menu entries for each custom layout path.
  foreach (layout_menu_item_load_all() as $menu_item) {
    if (!empty($menu_item->disabled)) {
      continue;
    }

    $path             = array();
    $page_arguments   = array($menu_item->name);
    $access_arguments = array($menu_item->name);
    $load_arguments   = array($menu_item->name, '%map', '%index');

    // Replace placeholders with named placeholders for known contexts.
    foreach (explode('/', $menu_item->path) as $position => $bit) {
      $placeholder = $bit;

      if (strpos($bit, '%') === 0) {
        $placeholder = '%layout_path';
      }

      $path[]             = $placeholder;
      $page_arguments[]   = $position;
      $access_arguments[] = $position;
    }

    $menu_path = implode('/', $path);
    $items[$menu_path] = layout_page_menu_item($menu_item->menu, $access_arguments, $page_arguments, $load_arguments);

    // Add a parent menu item if one is configured.
    if (isset($menu_item->menu['type']) && $menu_item->menu['type'] == 'default tab') {
      array_pop($path);
      $parent_path = implode('/', $path);
      $items[$parent_path] = layout_page_menu_item($menu_item->menu['parent'], $access_arguments, $page_arguments, $load_arguments);
    }
  }

  // A page in the Reports section to list all blocks and their modules.
  $items['admin/reports/blocks'] = array(
    'title' => 'Blocks',
    'description' => 'Overview of all blocks and their modules.',
    'page callback' => 'layout_block_list',
    'access callback' => 'user_access',
    'access arguments' => array('administer layouts'),
    'file' => 'layout.admin.inc',
  );

  // Create layout tabs for all possible entity bundles. Limit to entities that
  // define a menu context path.
  $all_info = _layout_get_all_info('layout_context');
  $entity_names = array();
  foreach ($all_info as $entity_type_name => $context_info) {
    if (!empty($context_info['menu paths'])) {
      $entity_names[] = $entity_type_name;
    }
  }

  foreach (entity_get_info() as $entity_type => $entity_info) {
    if (in_array($entity_type, $entity_names)) {
      foreach ($entity_info['bundles'] as $bundle_name => $bundle_info) {
        if (isset($bundle_info['admin'])) {
          $path = $bundle_info['admin']['path'];
          if (isset($bundle_info['admin']['bundle argument'])) {
            $bundle_arg = $bundle_info['admin']['bundle argument'];
          }
          else {
            $bundle_arg = $bundle_name;
          }

          $access = array(
            'access callback' => 'user_access',
            'access arguments' => array('administer layouts'),
          );

          $items["$path/layouts"] = array(
            'title' => 'Manage layouts',
            'page callback' => 'backdrop_get_form',
            'page arguments' => array('layout_entity_admin_form', $entity_type, $bundle_arg),
            'type' => MENU_LOCAL_TASK,
            'weight' => 2,
            'file' => 'layout.entity.admin.inc',
          ) + $access;
          $items["$path/layouts/add"] = array(
            'title' => 'Add layout',
            'title callback' => 'layout_entity_menu_title',
            'title arguments' => array($entity_type, $bundle_arg),
            'page callback' => 'backdrop_get_form',
            'page arguments' => array('layout_entity_admin_add_form', $entity_type, $bundle_arg),
            'file' => 'layout.entity.admin.inc',
            'type' => MENU_LOCAL_ACTION,
          ) + $access;
        }
      }
    }
  }

  return $items;
}

/**
 * Menu loader callback; Convert %layout_path placeholders to loaded objects.
 */
function layout_path_load($arg_value, $menu_item_name, $path_parts, $arg_position) {
  $menu_item = layout_menu_item_load($menu_item_name);
  $contexts = $menu_item->getContexts();
  $context_info = layout_get_context_info($contexts[$arg_position]->plugin);

  if (isset($context_info['load callback']) && function_exists($context_info['load callback'])) {
    return call_user_func_array($context_info['load callback'], array($arg_value));
  }

  // Pass-through the string argument if no load callback specified.
  return $arg_value;
}

/**
 * Create a menu item for Layout-provided pages.
 *
 * @param array $menu
 *   The configuration for this menu item as configured by the user.
 * @param $access_arguments
 *   The arguments for the menu system.
 * @param $page_arguments
 *   The page callback arguments for the menu system.
 * @param $load_arguments
 *   The magic loader arguments for the menu system.
 *
 * @return array
 *   The menu item array.
 */
function layout_page_menu_item(array $menu, array $access_arguments, array $page_arguments, array $load_arguments) {
  $item = array(
    'access callback' => 'layout_page_access',
    'access arguments' => $access_arguments,
    'page callback' => 'layout_page_callback',
    'page arguments' => $page_arguments,
    'load arguments' => $load_arguments,
    'file' => 'layout.pages.inc',
  );

  if (isset($menu['title'])) {
    $item['title'] = $menu['title'];
  }

  if (isset($menu['weight'])) {
    $item['weight'] = $menu['weight'];
  }

  if (empty($menu['type'])) {
    $menu['type'] = 'none';
  }

  switch ($menu['type']) {
    case 'normal':
      $item['type'] = MENU_NORMAL_ITEM;
      // Insert item into the proper menu
      $item['menu_name'] = $menu['name'];
      break;
    case 'tab':
      $item['type'] = MENU_LOCAL_TASK;
      break;
    case 'action':
      $item['type'] = MENU_LOCAL_ACTION;
      break;
    case 'default tab':
      $item['type'] = MENU_DEFAULT_LOCAL_TASK;
      break;
    case 'none':
    default:
      $item['type'] = MENU_CALLBACK;
      break;
  }

  return $item;
}

/**
 * Menu title callback; Return the title for editing a layout.
 */
function layout_page_title(Layout $layout) {
  // Page titles are run through check_plain() before output, so no escaping
  // here is intentional. See backdrop_get_title().
  return $layout->title;
}

/**
 * Menu access callback; Check access for any Layout-provided page.
 */
function layout_page_access() {
  module_load_include('inc', 'layout', 'layout.pages');
  $args = func_get_args();
  return call_user_func_array('_layout_page_access', $args);
}

/**
 * Title callback: Returns a label for the action link to create bundle layouts.
 *
 * @param string $entity_type
 *   The entity type such as "node", "user", "taxonomy_term", etc.
 * @param string|stdClass $bundle_arg
 *   The bundle as a string or object. The object may be a TaxonomyVocabulary
 *   or stdClass (in the case of a node type).
 *
 * @return string
 *   The translated label used for the local actions.
 *
 * @see layout_menu()
 */
function layout_entity_menu_title($entity_type, $bundle_arg) {
  module_load_include('inc', 'layout', 'layout.entity.admin');
  $entity_info = entity_get_info($entity_type);
  $single_bundle = (count($entity_info['bundles']) == 1) && isset($entity_info['bundles'][$entity_type]);

  if (!$single_bundle) {
    $bundle_label = _layout_entity_bundle_label($entity_type, $bundle_arg);
    return t('Add @bundle_label layout', array('@bundle_label' => $bundle_label));
  }
  else {
    return t('Add @entity layout', array('@entity' => $entity_info['label']));
  }
}

/**
 * Suppress the layout.
 *
 * This function should be called from within another module's page callback
 * when the layout should not be displayed, that is, content only. This can be
 * useful for modules that implement popup pages or other special pages where
 * the default layout would be distracting.
 *
 * @param bool $suppress
 *   If set to TRUE, the layout will be suppressed.
 *
 * @return bool
 *   TRUE if the layout can be suppressed, FALSE otherwise.
 *
 * @since 1.21.0 Function added.
 */
function layout_suppress($suppress = NULL) {
  $suppression_static = &backdrop_static(__FUNCTION__, FALSE);

  if (isset($suppress)) {
    $suppression_static = $suppress;
  }

  return $suppression_static;
}

/**
 * Route handler callback; Execute the current route item or wrap in a layout.
 *
 * @param $router_item
 *   The menu router item for the page currently being loaded.
 *
 * @return
 *   The fully built HTML content for this page, which will be wrapped in
 *   page.tpl.php.
 *
 * @ingroup callbacks
 */
function layout_route_handler($router_item) {
  // If a different delivery callback is specified, we're probably not returning
  // HTML, and it definitely should not be wrapped in a layout. Call the default
  // route handler, and return its response directly. Do the same if requested
  // by layout_suppress().
  if (!backdrop_is_html() || !empty($router_item['delivery_callback']) || $router_item['page_callback'] === 'layout_page_callback' || layout_suppress()) {
    return menu_default_route_handler($router_item);
  }

  $selected_layout = layout_get_layout_by_path(NULL, $router_item);

  // Safety check that we don't show an admin layout to a user who cannot view
  // the admin theme. This may happen because the cached layout list does not
  // include a permissions check on the admin theme.
  if ($selected_layout->name === 'admin_default' && !user_access('view the administration theme')) {
    $selected_layout = layout_load('default');
  }

  // Special handling for 404 and 403 pages to render in admin theme. The
  // current path will be the 404/403 system path, and we need to check the
  // original path, which is stored in "destination" by
  // backdrop_deliver_html_page().
  if (in_array(backdrop_get_http_header('Status'), array(
    '404 Not Found',
    '403 Forbidden',
  )) && user_access('view the administration theme')) {
    if (isset($_GET['destination']) && path_is_admin($_GET['destination'])) {
      $selected_layout = layout_load('admin_default');
    }
  }

  if ($selected_layout) {
    // Render the layout.
    $renderer = layout_create_renderer($selected_layout->renderer_name, $selected_layout);

    if ($selected_layout->isDefault()) {
      $renderer->ensurePageContentBlock();
    }

    return $renderer->render();
  }

  // Fallback code if even the expected default layout cannot be found.
  return menu_default_route_handler($router_item);
}

/**
 * Implements hook_theme()
 */
function layout_theme() {
  $base = array(
    'file' => 'layout.theme.inc',
  );

  $items = array(
    'layout' => array(
      'variables' => array(
        'content' => NULL,
        'settings' => NULL,
        'layout' => NULL,
        // @todo: Rename to layout_template_info in 2.x.
        'layout_info' => NULL,
        'renderer' => NULL,
        'attributes' => array(),
        'admin' => FALSE,
      ),
      'template' => 'templates/layout',
    ) + $base,
    'layout_reorder_layouts' => array(
      'render element' => 'element',
    ) + $base,
    'layout_content_form' => array(
      'template' => 'templates/layout-content-form',
      'render element' => 'form',
    ) + $base,
    'layout_hero_background_image' => array(
      'render element' => 'element',
    ) + $base,
    'layout_info' => array(
      'variables' => array('layout' => NULL),
    ) + $base,
    'layout_condition_info' => array(
      'variables' => array(
        'layout' => NULL,
        'show_empty' => TRUE,
      ),
    ) + $base,
    'layout_template_option' => array(
      'variables' => array('template_info' => NULL),
    ) + $base,
    'layout_template_info' => array(
      'variables' => array('template_info' => NULL),
    ) + $base,
    'layout_flexible_template_style_option' => array(
      'variables' => array('row_style' => NULL),
    ) + $base,
    'layout_menu_item_arguments_table' => array(
      'render element' => 'element',
    ) + $base,
    'layout_settings_context_table' => array(
      'render element' => 'element',
    ) + $base,
    'layout_action_links' => array(
      'render element' => 'element',
    ) + $base,
    'layout_conditions' => array(
      'render element' => 'element',
    ) + $base,
    'layout_region_inner' => array(
      'variables' => array(
        'blocks' => array(),
        'tag' => '',
        'classes' => array(),
        'attributes' => array(),
      ),
    ) + $base,
  );

  // Register all layout templates.
  $layout_templates = layout_get_layout_template_info();

  foreach ($layout_templates as $template) {
    if (!empty($template['template'])) {
      $theme_key = str_replace('-', '_', $template['template']);
      $items[$theme_key] = array(
        'variables' => array(
          'content' => NULL,
          'settings' => NULL,
          'layout' => NULL,
          // @todo: Rename to layout_template_info in 2.x.
          'layout_info' => NULL,
          'renderer' => NULL,
          'attributes' => array(),
          'admin' => FALSE,
        ),
        'template' => $template['template'],
        'path' => $template['path'],
        'base hook' => 'layout',
      );

      if (isset($template['file'])) {
        $items[$theme_key]['file'] = $template['file'];
      }
    }
  }

  // Register all styles.
  $styles = _layout_get_all_info('layout_style');

  foreach ($styles as $style) {
    if (!empty($style['block theme'])) {
      $items[$style['block theme']] = array(
        'variables' => array(
          'content' => NULL,
          'layout' => NULL,
          'block' => NULL,
          'style' => NULL,
          'settings' => array(),
          'attributes' => array(),
        ),
      );

      if (isset($style['file'])) {
        $items[$style['block theme']]['file'] = $style['file'];
      }

      if (isset($style['path'])) {
        $items[$style['block theme']]['path'] = $style['path'];
      }

      if (isset($style['template'])) {
        $items[$style['block theme']]['template'] = $style['template'];
      }
    }

    if (!empty($style['hook theme'])) {
      if (is_array($style['hook theme'])) {
        $items += $style['hook theme'];
      }
      elseif (function_exists($style['hook theme'])) {
        $style['hook theme']($items, $style);
      }
    }
  }

  return $items;
}

/**
 * Implements hook_permission().
 */
function layout_permission() {
  return array(
    'administer layouts' => array(
      'title' => t('Administer Layouts'),
      'description' => t('Create and modify layouts and blocks.'),
      'restrict access' => TRUE,
      'warning' => t('Change the access/visibility of menu items, layouts and blocks.'),
    ),
    'administer flexible templates' => array(
      'title' => t('Administer Flexible Templates'),
      'description' => t('Create, configure and delete flexible layout templates.'),
      'restrict access' => TRUE,
      'warning' => t('Manage all aspects of flexible layout templates, including deleting them.'),
    ),
  );
}

/**
 * Implements hook_config_info().
 */
function layout_config_info() {
  $prefixes['layout.settings'] = array(
    'label' => t('Layout settings'),
    'group' => t('Configuration'),
  );

  $prefixes['layout.layout'] = array(
    'name_key' => 'name',
    'label_key' => 'title',
    'group' => t('Layouts'),
  );

  $prefixes['layout.menu_item'] = array(
    'name_key' => 'name',
    'label_key' => 'path',
    'group' => t('Layout menu items'),
  );

  $prefixes['layout.flexible'] = array(
    'name_key' => 'name',
    'label_key' => 'title',
    'group' => t('Flexible layout templates'),
  );

  return $prefixes;
}

/**
 * Implements hook_library_info().
 */
function layout_library_info() {
  $path = backdrop_get_path('module', 'layout');

  $libraries['bootstrap4-gs'] = array(
    'title' => 'Bootstrap4 Grid System',
    'website' => 'http://v4-alpha.getbootstrap.com/layout/grid/',
    'version' => BACKDROP_VERSION,
    'css' => array(
      $path . '/css/grid-flexbox.css' => array(),
    ),
    'js' => array(
      $path . '/js/grid-fallback.js' => array(),
    ),
  );

  return $libraries;
}

/**
 * Implements hook_layout_api().
 */
function layout_layout_api() {
  return array(
    'file' => 'includes/layout.layout.inc',
  );
}

/**
 * Implements hook_block_info().
 */
function layout_block_info() {
  $blocks = array();
  $blocks['custom_block'] = array(
    'info' => t('Custom block'),
    'description' => t('A basic block for adding custom text.'),
    'class' => 'BlockText',
  );

  $blocks['hero'] = array(
    'info' => t('Hero block'),
    'description' => t('A hero block often consists of text over a background image, though either are optional.'),
    'class' => 'BlockHero',
  );

  return $blocks;
}

/**
 * Implements hook_autoload_info().
 */
function layout_autoload_info() {
  return array(
    'Block' => 'includes/block.class.inc',
    'BlockBroken' => 'includes/block.class.inc',
    'BlockHero' => 'includes/block.hero.inc',
    'BlockLegacy' => 'includes/block_legacy.class.inc',
    'BlockText' => 'includes/block.text.inc',
    'Layout' => 'includes/layout.class.inc',
    'LayoutFlexibleTemplate' => 'includes/layout_flexible.class.inc',
    'LayoutHandler' => 'includes/layout_handler.class.inc',
    'LayoutHandlerBroken' => 'includes/layout_handler.class.inc',
    'LayoutMenuItem' => 'includes/layout_menu_item.class.inc',

    // Exceptions.
    'LayoutException' => 'includes/layout.exceptions.inc',
    'LayoutMissingException' => 'includes/layout.exceptions.inc',
    'LayoutSaveException' => 'includes/layout.exceptions.inc',

    // Context handlers.
    'EntityLayoutContext' => 'plugins/context/entity_layout_context_handler.inc',
    'LayoutContextBroken' => 'plugins/context/layout_context.inc',
    'LayoutOverridesPathContext' => 'plugins/context/layout_context.inc',
    'LayoutStringContext' => 'plugins/context/layout_context.inc',
    'LayoutContext' => 'plugins/context/layout_context.inc',

    // Access handlers.
    'EntityBundleLayoutAccess' => 'plugins/access/entity_bundle_layout_access.inc',
    'EntityIDLayoutAccess' => 'plugins/access/entity_id_layout_access.inc',
    'FrontLayoutAccess' => 'plugins/access/front_layout_access.inc',
    'HttpResponseCodeLayoutAccess' => 'plugins/access/http_response_code_layout_access.inc',
    'LanguageLayoutAccess' => 'plugins/access/language_layout_access.inc',
    'LayoutAccess' => 'plugins/access/layout_access.inc',
    'LayoutAccessBroken' => 'plugins/access/layout_access.inc',
    'LayoutAccessNegatable' => 'plugins/access/layout_access.inc',
    'PathLayoutAccess' => 'plugins/access/path_layout_access.inc',
    'UserCompareLayoutAccess' => 'plugins/access/user_compare_layout_access.inc',
    'UserPermissionLayoutAccess' => 'plugins/access/user_permission_layout_access.inc',
    'UserRoleLayoutAccess' => 'plugins/access/user_role_layout_access.inc',

    // Renderer handlers.
    'LayoutRendererEditor' => 'plugins/renderers/layout_renderer_editor.inc',
    'LayoutRendererFlexible' => 'plugins/renderers/layout_renderer_flexible.inc',
    'LayoutRendererStandard' => 'plugins/renderers/layout_renderer_standard.inc',

    // Styles.
    'LayoutStyle' => 'plugins/styles/layout_style_default.inc',
    'LayoutStyleDynamic' => 'plugins/styles/layout_style_dynamic.inc',

    // Relationships.
    'LayoutRelationship' => 'plugins/relationships/layout_relationship.inc',
    'LayoutRelationshipAuthorFromNode' => 'plugins/relationships/author_from_node.inc',
    'LayoutRelationshipBroken' => 'plugins/relationships/layout_relationship.inc',
  );
}

/**
 * Implements hook_contextual_links_view_alter()
 */
function layout_contextual_links_view_alter(&$element, $items) {
  // Convert the link to manage blocks to use a shortened URL that lands the
  // user on the overall layout edit screen with a modal opened, instead of the
  // path to the block edit page itself.
  $links = &$element['#links'];

  if (isset($links['layout-configure-redirect-'])) {
    if ($position = strpos($links['layout-configure-redirect-']['href'], '/configure-redirect')) {
      $last_slash = strrpos($links['layout-configure-redirect-']['href'], '/');
      $uuid = substr($links['layout-configure-redirect-']['href'], $last_slash + 1);
      $links['layout-configure-redirect-']['fragment'] = 'configure-block:' . $uuid;
    }
  }
}

/**
 * Load an individual layout.
 *
 * @param string $layout_name
 *   The layout machine name to load.
 * @param bool $skip_menu_items
 *   Flag to skip the attempted loading of menu items for the loaded layouts.
 *   This should be set to TRUE if loading layouts that definitely do not have
 *   menu items associated with them, for example the default layouts or a
 *   layout that overrides an existing menu path.
 *
 * @return Layout|boolean
 */
function layout_load($layout_name, $skip_menu_items = NULL) {
  // Skip menu item loading for default layouts, as we know they do not have
  // an associated menu item.
  if (is_null($skip_menu_items)) {
    $skip_menu_items = in_array($layout_name, array('default', 'admin_default'));
  }

  $layouts = layout_load_multiple(array($layout_name), $skip_menu_items);
  return $layouts[$layout_name];
}

/**
 * Load multiple layouts based on a particular criteria.
 *
 * @param array $layout_names
 *   The names of the layouts to be loaded.
 * @param bool $skip_menu_items
 *   Flag to skip the attempted loading of menu items for the loaded layouts.
 *   This should be set to TRUE if loading layouts that definitely do not have
 *   menu items associated with them, for example the default layouts or a
 *   layout that overrides an existing menu path.
 *
 * @return Layout[]
 *   An array of Layout object instances.
 */
function layout_load_multiple($layout_names, $skip_menu_items = FALSE) {
  $loaded_layouts = &backdrop_static(__FUNCTION__, array());

  $layouts_to_load = array();
  foreach ($layout_names as $layout_name) {
    if (!isset($loaded_layouts[$layout_name])) {
      $layouts_to_load[] = $layout_name;
    }
  }

  if ($layouts_to_load) {
    $menu_items = layout_menu_item_load_multiple($layout_names);

    // Cache the raw config files once read.
    $configs = layout_get_all_configs('layout');

    // Create the layout instances and associate the menu items with each.
    foreach ($layouts_to_load as $layout_name) {
      if (isset($configs[$layout_name])) {
        $layout_data = $configs[$layout_name];
        $loaded_layouts[$layout_name] = new Layout($layout_data);

        // Associate the applicable menu item.
        if (isset($layout_data['path']) && !$skip_menu_items) {
          // Most of the time, layouts will be loaded as a group, including the
          // layout that owns the menu item.
          if (isset($menu_items[$layout_data['path']])) {
            $loaded_layouts[$layout_name]->menu_item = $menu_items[$layout_data['path']];
          }
          // In the situation that a layout is loaded separately of its menu
          // item owner, load the menu item by path.
          elseif ($menu_item = layout_menu_item_load_multiple_by_path($layout_data['path'])) {
            $loaded_layouts[$layout_name]->menu_item = $menu_item;
          }
        }
      }
    }
  }

  // Return the requested layouts.
  $layouts = array();

  foreach ($layout_names as $layout_name) {
    if (isset($loaded_layouts[$layout_name])) {
      $layouts[$layout_name] = $loaded_layouts[$layout_name];
    }
    else {
      $layouts[$layout_name] = FALSE;
    }
  }

  return $layouts;
}

/**
 * Load all layouts for a given router item and allow other modules to alter
 * them and/or set their contexts.
 *
 * @param array $router_item
 *   The fully built menu router item, e.g., what is returned by menu_get_item().
 * @param bool $skip_menu_items
 *   Flag to skip the attempted loading of menu items for the loaded layouts.
 *
 * @return Layout[]
 *   An array of load Layout object instances.
 */
function layout_load_multiple_by_router_item($router_item, $skip_menu_items = NULL) {
  $href = $router_item['href'];
  $layouts_by_item = &backdrop_static(__FUNCTION__, array());

  if (isset($layouts_by_item[$href])) {
    return $layouts_by_item[$href];
  }

  $layouts = layout_load_multiple_by_path($router_item['path'], $skip_menu_items);
  backdrop_alter('layout_load_by_router_item', $layouts, $router_item);
  $layouts_by_item[$href] = $layouts;
  return $layouts;
}

/**
 * Load all layouts at a given path.
 *
 * This function does not invoke hook_layout_load_by_router_item_alter(). In
 * general, developers should use layout_load_multiple_by_router_item() rather
 * than layout_load_multiple_by_path() to allow client modules to alter the
 * layouts and only call this function in situations where client alteration is
 * not desired and/or the router item is not available. Examples where this
 * might be needed:
 * - Inside a hook_menu() implementation (see dashboard_menu()).
 * - Inside a hook_layout_load_by_router_item_alter() implementation (see
 *   node_layout_load_by_router_item_alter()).
 *
 * @param string $path
 *   The menu routing path, with all placeholders represented by "%" symbols.
 * @param bool $skip_menu_items
 *   Flag to skip the attempted loading of menu items for the loaded layouts.
 *
 * @return Layout[]
 *   An array of load Layout object instances.
 *
 * @see dashboard_menu()
 * @see node_layout_load_by_router_item_alter()
 */
function layout_load_multiple_by_path($path, $skip_menu_items = NULL) {
  if ($cache = cache('layout_path')->get($path)) {
    $layouts = $cache->data;

    // Populate these cached layouts into layout_load_multiple() to optimize
    // any future calls to it.
    $static_cache = &backdrop_static('layout_load_multiple', array());
    $static_cache = array_merge($layouts, $static_cache);
  }
  else {
    $layout_names = layout_get_path_layout_names($path);

    if (empty($layout_names)) {
      // Skip loading menu items for the default layouts.
      if (is_null($skip_menu_items)) {
        $skip_menu_items = TRUE;
      }

      if (path_is_admin($path)) {
        $layout_names[] = 'admin_default';
      }
      else {
        $layout_names[] = 'default';
      }
    }

    $layouts = layout_load_multiple($layout_names, $skip_menu_items);
    cache('layout_path')->set($path, $layouts);
  }

  return $layouts;
}

/**
 * Return an array of all layouts as fully loaded Layout objects.
 *
 * Note that this operation can be very expensive and its use is discouraged.
 * Use layout_load_multiple() to load specific layouts.
 *
 * @return Layout[]
 *   An array of Layout object instances.
 */
function layout_load_all() {
  $configs = layout_get_all_configs('layout');
  $layout_names = array_keys($configs);
  return layout_load_multiple($layout_names);
}

/**
 * Load an individual Layout menu item.
 *
 * @return LayoutMenuItem|boolean
 */
function layout_menu_item_load($menu_item_name) {
  $menu_items = layout_menu_item_load_multiple(array($menu_item_name));

  // Returned menu items are by path, so return the first item if it exists.
  if ($path = key($menu_items)) {
    return $menu_items[$path];
  }
  else {
    return FALSE;
  }
}

/**
 * Load menu items by name.
 *
 * @param array $menu_item_names
 *   An array of menu item names, if left empty, all Layout menu items will
 *   be returned.
 *
 * @return array
 *   An array of loaded LayoutMenuItem instances, keyed by the layout menu item
 *   path.
 */
function layout_menu_item_load_multiple($menu_item_names = NULL) {
  $loaded_menu_items = &backdrop_static(__FUNCTION__, array());

  $menu_items_to_load = array();
  foreach ($menu_item_names as $menu_item_name) {
    if (!isset($loaded_menu_items[$menu_item_name])) {
      $menu_items_to_load[] = $menu_item_name;
    }
  }

  if ($menu_items_to_load) {
    $configs = layout_get_all_configs('menu_item');
    foreach ($menu_items_to_load as $menu_item_name) {
      if (isset($configs[$menu_item_name])) {
        $loaded_menu_items[$menu_item_name] = new LayoutMenuItem($configs[$menu_item_name]);
      }
    }
  }

  // Return the requested menu items.
  $menu_items = array();
  foreach ($menu_item_names as $menu_item_name) {
    if (isset($loaded_menu_items[$menu_item_name])) {
      $path = $loaded_menu_items[$menu_item_name]->path;
      $menu_items[$path] = $loaded_menu_items[$menu_item_name];
    }
  }

  return $menu_items;
}

/**
 * Load an individual Layout menu item based on its path.
 */
function layout_menu_item_load_multiple_by_path($path) {
  $configs = layout_get_all_configs('menu_item');
  foreach ($configs as $menu_item_name => $config) {
    if ($config['path'] === $path) {
      return layout_menu_item_load($menu_item_name);
    }
  }

  return FALSE;
}

/**
 * Return an array of all menu items as fully loaded LayoutMenuItem objects.
 *
 * Note this operation may be expensive. It should only be called in areas where
 * the results will be cached, e.g. on menu rebuild.
 */
function layout_menu_item_load_all() {
  $configs = layout_get_all_configs('menu_item');
  $menu_item_names = array_keys($configs);
  return layout_menu_item_load_multiple($menu_item_names);
}

/**
 * Read all configuration files from disk of a particular layout type.
 *
 * This method provides basic caching around Layout's config files.
 *
 * @param $type
 *   Either "layout" or "menu_item".
 *
 * @return array
 *   An array of all configs for the specified type.
 */
function layout_get_all_configs($type) {
  // Cache the raw config files once read.
  if ($cache = cache()->get('layout:' . $type . ':config')) {
    $configs = $cache->data;
  }
  else {
    $configs = array();

    $config_names = config_get_names_with_prefix('layout.' . $type . '.');
    foreach ($config_names as $config_file) {
      $config = config($config_file);
      $data = $config->get();
      $data += array(
        'weight' => 0,
      );
      $configs[$data['name']] = $data;
    }

    // Sort the configs by path and weight.
    backdrop_sort($configs, array(
      'path' => SORT_STRING,
      'weight' => SORT_NUMERIC,
    ));

    // Put default layouts at the bottom.
    if ($type === 'layout') {
      $default = $configs['default'];
      $admin_default = $configs['admin_default'];
      unset($configs['default']);
      unset($configs['admin_default']);
      $configs['default'] = $default;
      $configs['admin_default'] = $admin_default;
    }

    cache()->set('layout:' . $type . ':config', $configs);
  }

  return $configs;
}

/**
 * Get a list of layouts that share a particular path.
 */
function layout_get_path_layout_names($path) {
  $path_map = &backdrop_static(__FUNCTION__, array());

  if (empty($path_map)) {
    $configs = layout_get_all_configs('layout');
    foreach ($configs as $layout_name => $config) {
      if (isset($config['path'])) {
        $path_map[$config['path']][] = $layout_name;
      }
    }
  }

  return isset($path_map[$path]) ? $path_map[$path] : array();
}

/**
 * Check if a path is provided by Layout module, as in a custom layout path.
 *
 * @return
 *   Boolean TRUE if Layout module provides a path, FALSE if another module
 *   specified the path, or NULL if a path does not exist in the system.
 */
function layout_provides_path($path) {
  if (empty($path)) {
    return FALSE;
  }

  $result = db_query('SELECT * FROM {menu_router} WHERE path = :path', array(':path' => $path));
  $return = NULL;

  // If any page callback exists at this path, allow it to trump custom layouts.
  foreach ($result as $router) {
    if ($router->page_callback == 'layout_page_callback') {
      $return = TRUE;
    }
    else {
      $return = FALSE;
      break;
    }
  }

  return $return;
}

/**
 * Get the layout which is active based on a path or router item.
 *
 * This may also be used to get the current layout on a page if no parameters
 * are passed. In which case the current path will be used.
 *
 * @param string $path
 *   The menu routing path, with all placeholders represented by "%" symbols.
 * @param array $router_item
 *   The menu router item for the page currently being loaded.
 *   The $path parameter will be ignored if $router_item is specified.
 * @param bool $is_layout_page
 *   Flag that says whether this is being called from the page callback for a
 *   layout-provided page.
 *
 * @return Layout
 *   The Layout object for the specified path.
 *
 * @since 1.4.0
 */
function layout_get_layout_by_path($path = NULL, $router_item = NULL, $is_layout_page = FALSE) {
  if (!isset($router_item)) {
    $router_item = menu_get_item($path);
  }

  // Use the static cache, but keyed on the normal path (such as node/1), rather
  // than the system path (such as node/%), since client modules might serve up
  // different layouts for the same system path.
  $href = $router_item['href'];
  $layouts_by_path = &backdrop_static(__FUNCTION__, array());
  if (isset($layouts_by_path[$href])) {
    return $layouts_by_path[$href];
  }

  $layouts = layout_load_multiple_by_router_item($router_item, !$is_layout_page);
  $selected_layout = NULL;
  foreach ($layouts as $layout) {
    // Contexts must have their data set before the layout's access may be
    // checked.
    $menu_contexts = $layout->getContexts(LayoutContext::USAGE_TYPE_MENU);
    foreach ($menu_contexts as $menu_context) {
      $menu_context->setDataFromRouter($router_item);
    }
    backdrop_static_reset('Layout::getContexts');

    if (!$layout->disabled && $layout->checkAccess()) {
      $selected_layout = $layout;
      break;
    }
  }

  if (!$is_layout_page) {
    // If no layout matches at the path, use a default layout.
    if (!$selected_layout) {
      if (path_is_admin($router_item['path']) && user_access('view the administration theme')) {
        $selected_layout = layout_load('admin_default');
      }
      else {
        $selected_layout = layout_load('default');
      }
    }
  }

  $layouts_by_path[$href] = $selected_layout;
  return $selected_layout;
}

/**
 * Implements hook_flush_caches().
 */
function layout_flush_caches() {
  return array('layout_path');
}

/**
 * Reset all caches provided by Layout module.
 */
function layout_reset_caches() {
  cache()->delete('layout:layout:config');
  cache()->delete('layout:menu_item:config');
  cache()->delete('layout_info');
  cache('layout_path')->flush();

  backdrop_static_reset('layout_load_multiple');
  backdrop_static_reset('layout_menu_item_load_multiple');
  backdrop_static_reset('layout_get_path_layout_names');
  backdrop_static_reset('layout_get_layout_template_info');
  backdrop_static_reset('layout_get_block_info');
  backdrop_static_reset('layout_get_layout_tempstore');
  backdrop_static_reset('_layout_include_files');
  backdrop_static_reset('_layout_get_all_info');
}

/**
 * Load all include files for modules that implement hook_layout_api().
 */
function _layout_include_files() {
  $included = &backdrop_static(__FUNCTION__, FALSE);
  if (!$included) {
    foreach (module_implements('layout_api') as $module) {
      $function = $module . '_layout_api';
      $api_info = $function();
      if (isset($api_info['file'])) {
        include_once(BACKDROP_ROOT . '/' . backdrop_get_path('module', $module) . '/' . $api_info['file']);
      }
    }
    $included = TRUE;
  }
}

/**
 * Load layout-related information from modules.
 */
function _layout_get_all_info($data_type, $init = array()) {
  $all_info = &backdrop_static(__FUNCTION__);

  if (!isset($all_info[$data_type])) {
    _layout_include_files();
    $all_info[$data_type] = $init;

    foreach (module_implements($data_type . '_info') as $module) {
      $function = $module . '_' . $data_type . '_info';
      $data = $function();
      $module_path = backdrop_get_path('module', $module);

      foreach ($data as $key => $info) {
        $info['module'] = $module;
        $info['name'] = $key;

        if (isset($info['path'])) {
          $info['path'] = $module_path . '/' . $info['path'];
        }
        else {
          $info['path'] = $module_path;
        }

        $all_info[$data_type][$key] = $info;
      }
    }
  }

  return $all_info[$data_type];
}

/**
 * Load the information of either a single layout template or all available
 * layout templates.
 *
 * @param string $template_name
 *   Optionally specify a name of a single layout template, e.g. "boxton" or
 *   "simmons". If no layout template name is specified, information for all
 *   layout templates will be returned.
 *
 * @param boolean $rebuild
 *   Whether the list of layout template info needs to be rebuilt (see
 *   https://github.com/backdrop/backdrop-issues/issues/984). The rebuild is
 *   required only on specific cases, so this defaults to FALSE. That way, the
 *   rest of the times the layout cache is used (when available) for performance
 *   reasons.
 *
 * @return array|boolean
 *   The layout template information, as returned by either a stand-alone
 *   template .info file, or through a module's hook_layout_template_info().
 *
 * @see hook_layout_template_info()
 * @see hook_layout_info()
 */
function layout_get_layout_template_info($template_name = NULL, $rebuild = FALSE) {
  $info = &backdrop_static(__FUNCTION__);

  // Try getting a cached list of layout info.
  if (!isset($info) && !$rebuild) {
    // @todo: Rename cache key to layout_template_info in 2.x.
    $cache = cache('cache')->get('layout_info');

    if ($cache && $cache->data) {
      $info = $cache->data;
    }
  }

  // Rebuild the list of layout info.
  if (!isset($info) || $rebuild) {
    $files = backdrop_system_listing('/^' . BACKDROP_PHP_FUNCTION_PATTERN . '\.info$/', 'layouts', 'name', 0);
    $init = array();

    foreach ($files as $name => $file) {
      $init[$name] = backdrop_parse_info_file($file->uri);

      // Skip modules or themes that have been placed in the wrong directory.
      if (isset($init[$name]['type']) && $init[$name]['type'] != 'layout') {
        unset($init[$name]);
        continue;
      }

      $init[$name]['path'] = dirname($file->uri);
      $init[$name]['title'] = $init[$name]['name'];
      $init[$name]['name'] = $name;
    }
    $info = _layout_get_all_info('layout_template', $init);
    // Account for implementations of the deprecated hook_layout_info().
    $info = _layout_get_all_info('layout', $info);

    // Populate defaults.
    foreach ($info as $name => $layout_template_info) {
      $info[$name] += array(
        'hidden' => FALSE,
        'preview' => 'preview.png',
        'default region' => 'content',
        'stylesheets' => array(
          'all' => array(str_replace('_', '-', $name) . '.css'),
        ),
      );
      if (!isset($info[$name]['template'])) {
        $template_path = BACKDROP_ROOT . '/' . $layout_template_info['path'] . '/layout--' . str_replace('_', '-', $name) . '.tpl.php';

        if (is_file($template_path)) {
          $info[$name]['template'] = 'layout--' . str_replace('_', '-', $name);
        }
      }
    }

    // Sort the available layouts by display name.
    backdrop_sort($info, array('title' => SORT_STRING));

    cache('cache')->set('layout_info', $info);
  }

  if ($template_name) {
    if (isset($info[$template_name])) {
      return $info[$template_name];
    }
    else {
      return FALSE;
    }
  }
  else {
    return $info;
  }
}

/**
 * Load the layout template information for a single layout template name.
 *
 * Duplicates the function layout_get_layout_template_info() to maintain
 * compatibility. Should not be used in new code.
 *
 * @param string $layout_name
 *   The name of the layout template, e.g. "one_column" or
 *   "three_three_four_column". If no layout template is specified, all layout
 *  info will be returned.
 *
 * @return array|boolean
 *   The layout template information, as returned by either a stand-alone
 *   template .info file, or through a module's hook_layout_template_info().
 *
 * @deprecated since 1.4.0
 * @see layout_get_layout_template_info()
 */
function layout_get_layout_info($layout_name = NULL) {
  return layout_get_layout_template_info($layout_name);
}

/**
 * Load all layout context information from modules.
 *
 * @param string $plugin_name
 *   The name of the plugin.
 *
 * @return array
 */
function layout_get_context_info($plugin_name) {
  $info = _layout_get_all_info('layout_context');

  return isset($info[$plugin_name]) ? $info[$plugin_name] : FALSE;
}

/**
 * Fetch all relevant relationships.
 *
 * Relevant relationships are any relationship that can be created based upon
 * the list of existing contexts. For example, the 'node author' relationship
 * is relevant if there is a 'node' context, but makes no sense if there is
 * not one.
 *
 * @param $contexts
 *   An array of contexts used to figure out which relationships are relevant.
 *
 * @return
 *   An array of relationship keys that are relevant for the given set of
 *   contexts.
 */
function layout_relationships_get_relevant_info($contexts) {
  $relevant = array();
  $relationships = _layout_get_all_info('layout_relationship');

  foreach ($contexts as $context) {
    // Go through each relationship
    foreach ($relationships as $rid => $relationship) {
      $handler = layout_create_handler('layout_relationship', $rid);
      if ($children = $handler->getChildren($rid)) {
        foreach ($children as $child_rid => $child) {
          if ($child['context'] == $context->plugin) {
            $relevant[$child_rid] = $child;
          }
        }
      }
      else {
        if ($relationship['context'] == $context->plugin) {
          $relevant[$rid . ':relationship'] = $relationship;
        }
      }
    }
  }

  return $relevant;
}

/**
 * Load all layout relationship information from modules.
 *
 * @return array
 */
function layout_get_relationship_info($plugin_name) {
  $info = _layout_get_all_info('layout_relationship');
  return isset($info[$plugin_name]) ? $info[$plugin_name] : FALSE;
}

/**
 * Load all layout access information from modules.
 *
 * @return array
 */
function layout_get_access_info($plugin_name) {
  $info = _layout_get_all_info('layout_access');
  return isset($info[$plugin_name]) ? $info[$plugin_name] : FALSE;
}

/**
 * Load all layout renderer information from modules.
 *
 * @return array
 */
function layout_get_renderer_info($plugin_name) {
  $info = _layout_get_all_info('layout_renderer');
  return isset($info[$plugin_name]) ? $info[$plugin_name] : FALSE;
}

/**
 * Load all layout style information from modules.
 */
function layout_get_style_info($plugin_name) {
  $info = _layout_get_all_info('layout_style');
  return isset($info[$plugin_name]) ? $info[$plugin_name] : FALSE;
}

/**
 * Get information about all blocks or just a single one.
 *
 * @param $block_module
 *   The name of a module providing the desired block.
 * @param $block_delta
 *   The key of the block within that module.
 *
 * @return array|FALSE
 *   The information from hook_block_info() for the requests block(s).
 */
function layout_get_block_info($block_module = NULL, $block_delta = NULL) {
  $block_info = &backdrop_static(__FUNCTION__, array(
    'all' => NULL, // Set TRUE when block info for all modules has been loaded.
    'modules' => array(), // The actual list of stored block info, per module.
  ));

  if (isset($block_module)) {
    $modules = array($block_module);
  }
  elseif (!isset($block_info['all'])) {
    $modules = module_implements('block_info');
    $block_info['all'] = TRUE;
  }
  else {
    $modules = array();
  }

  // Load each module's block info that is required.
  $new_block_info = array();
  foreach ($modules as $module) {
    if (!isset($block_info['modules'][$module])) {
      $new_block_info[$module] = module_invoke($module, 'block_info');
    }
  }

  // Alter and merge the collection of new blocks.
  if (!empty($new_block_info)) {
    backdrop_alter('block_info', $new_block_info);
    $block_info['modules'] = array_merge($block_info['modules'], $new_block_info);
  }

  // Return partial or full results based on the requested properties.
  if (isset($block_module) && isset($block_delta)) {
    if (isset($block_info['modules'][$block_module][$block_delta])) {
      return $block_info['modules'][$block_module][$block_delta];
    }
    else {
      return FALSE;
    }
  }
  elseif (isset($block_module)) {
    if (isset($block_info['modules'][$block_module])) {
      return $block_info['modules'][$block_module];
    }
    else {
      return FALSE;
    }
  }

  return $block_info['modules'];
}

/**
 * Helper function to get a handler class name based on the plugin name.
 */
function layout_get_handler_name($plugin_type, $plugin_name) {
  // Block "plugins" for Layouts are wrappers around the generic block system.
  $broken_class = NULL;

  if ($plugin_type === 'block') {
    $parts = explode(':', $plugin_name);
    list($module, $delta) = $parts;
    $info = layout_get_block_info($module, $delta);

    if ($info) {
      if (isset($info['class'])) {
        $class_name = $info['class'];
      }
      else {
        $class_name = 'BlockLegacy';
      }
      // Field blocks use the field name as the third part of the plugin name.
      // If the field no longer exists, return a broken block.
      if ($delta == 'field_block' && isset($parts[2])) {
        $field_name = $parts[2];
        $available_fields = field_get_block_list();

        if (empty($available_fields[$field_name])) {
          $class_name = 'BlockBroken';
        }
      }
    }
    else {
      $class_name = 'BlockBroken';
    }
  }
  else {
    $info = _layout_get_all_info($plugin_type);

    switch ($plugin_type) {
      case 'layout_access':
        $broken_class = 'LayoutAccessBroken';
        break;
      case 'layout_context':
        $broken_class = 'LayoutContextBroken';
        break;
      case 'layout_relationship':
        $broken_class = 'LayoutRelationshipBroken';
        break;
      case 'layout_style':
        $broken_class = 'LayoutStyle';
        break;
    }

    if (isset($info[$plugin_name]['class']) && class_exists($info[$plugin_name]['class'])) {
      $class_name = $info[$plugin_name]['class'];
    }
    else {
      $class_name = $broken_class;
    }
  }

  return $class_name;
}

/**
 * Helper function to instantiate handlers when loading from config.
 *
 * @param string $plugin_type
 *   The type of plugin being loaded, i.e. 'context', 'access', etc.
 * @param string $plugin_name
 *   The name of the plugin, as keyed by that plugin type's info hooks.
 * @param array $config
 *   The configuration options for the handler being created.
 *
 * @return
 *   A handler object instance of the specified plugin type.
 */
function layout_create_handler($plugin_type, $plugin_name, array $config = array()) {
  $handler_name = layout_get_handler_name($plugin_type, $plugin_name);
  return new $handler_name($plugin_name, $config);
}

/**
 * Helper function to create a Layout Context.
 *
 * @return LayoutContext
 */
function layout_create_relationship($relationship_plugin_name, $config = array()) {
  return layout_create_handler('layout_relationship', $relationship_plugin_name, $config);
}

/**
 * Helper function to create a Layout Context.
 *
 * @return LayoutContext
 */
function layout_create_context($context_plugin_name, $config = array()) {
  return layout_create_handler('layout_context', $context_plugin_name, $config);
}

/**
 * Helper function to create a Layout Access.
 *
 * @return LayoutAccess
 */
function layout_create_access($access_plugin_name, $config = array()) {
  return layout_create_handler('layout_access', $access_plugin_name, $config);
}

/**
 * Helper function to create a Layout Renderer.
 *
 * @return LayoutRendererStandard|LayoutRendererEditor
 */
function layout_create_renderer($renderer_plugin_name, Layout $layout) {
  // Renderers do not have "broken" classes if they do not exist. As renderers
  // are not part of configuration, they should never go missing.
  $renderer_info = layout_get_renderer_info($renderer_plugin_name);
  return new $renderer_info['class']($layout, $renderer_info);
}

/**
 * Get a layout or menu item currently being edited from the tempstore.
 *
 * If a layout is not yet being edited, the layout will be loaded from
 * configuration.
 *
 * @param string $name
 *   The machine name of the Layout item to load.
 * @param string $type
 *   The type of item to load. Must be either "layout" or "menu_item".
 */
function layout_get_layout_tempstore($name, $type = 'layout') {
  $caches = &backdrop_static(__FUNCTION__, array());

  if (!isset($caches[$type][$name])) {
    // Try loading from tempstore first to get in-progress changes.
    $item = tempstore_get('layout.' . $type, $name);

    if (!$item) {
      if ($type == 'layout') {
        $item = layout_load($name);
      }
      elseif ($type == 'menu_item') {
        $item = layout_menu_item_load($name);
      }
    }

    $caches[$type][$name] = $item;
  }

  return $caches[$type][$name];
}

/**
 * Store changes to a layout or menu item in the temporary store.
 *
 * @param Layout|LayoutMenuItem $item
 *   The Layout item to save into tempstore.
 * @param string $type
 *   The type of item to save. Must be either "layout" or "menu_item".
 */
function layout_set_layout_tempstore($item, $type = 'layout') {
  if (empty($item->name)) {
    return;
  }

  $item->locked = array(
    'uid' => $GLOBALS['user']->uid,
    'updated' => REQUEST_TIME,
  );
  tempstore_set('layout.' . $type, $item->name, $item, 604800);
}

/**
 * Remove an item from the object cache.
 */
function layout_clear_layout_tempstore($name, $type = 'layout') {
  tempstore_clear('layout.' . $type, $name);
}

/**
 * Menu loader callback to load a Layout cache object.
 */
function layout_tempstore_load($layout_name) {
  return layout_get_layout_tempstore($layout_name, 'layout');
}

/**
 * Menu loader callback to load a Layout cache object.
 */
function layout_tempstore_menu_item_load($layout_name) {
  return layout_get_layout_tempstore($layout_name, 'menu_item');
}

/**
 * Menu loader to load an individual block from a layout.
 */
function layout_tempstore_block_load($layout_block_uuid, $layout_name) {
  $layout = layout_tempstore_load($layout_name);
  $block = FALSE;

  if (isset($layout->in_progress['block']) && $layout->in_progress['block']->uuid === $layout_block_uuid) {
    $block = $layout->in_progress['block'];
  }
  elseif (isset($layout->content[$layout_block_uuid])) {
    $block = $layout->content[$layout_block_uuid];
  }

  return $block;
}

/**
 * Given a path with placeholders (%), determine the required contexts.
 *
 * @param string $path
 *   The path for which required contexts should be retrieved.
 *
 * @return array
 *   An array of required contexts that match the given path.
 */
function layout_context_required_by_path($path) {
  $required_context_info = array();

  // Populate each required context on the available known handlers.
  $all_info = _layout_get_all_info('layout_context');
  foreach ($all_info as $context_info) {
    foreach ($context_info['menu paths'] as $context_path) {
      // Remove named placeholders to just match on % symbols.
      $cleaned_path = preg_replace('/%[a-z0-9_]+/', '%', $context_path);

      // If it is an exact path match, assign the context without a position.
      if (strpos($path, '%') === FALSE && $path === $cleaned_path) {
        $required_context_info[$context_info['name']] = array(
          'plugin' => $context_info['name'],
        );
      }
      // If the path matches based on % placeholders, add this context as a
      // required context info in the correct order.
      elseif (strpos($path, $cleaned_path) === 0) {
        // Determine the argument placement within the path.
        $parts = explode('/', $context_path);
        foreach ($parts as $part_index => $part) {
          if (!empty($context_info['path placeholder']) && $part === $context_info['path placeholder']) {
            $required_context_info[$part_index] = array(
              'plugin' => $context_info['name'],
              'position' => $part_index,
            );
          }
        }
      }
    }
  }

  // If any placeholders are not filled, populate with a placeholder context
  // that can be modified.
  $parts = explode('/', $path);
  foreach ($parts as $part_index => $part) {
    if ($part === '%' && !isset($required_context_info[$part_index])) {
      $required_context_info[$part_index] = array(
        'plugin' => 'string',
        'position' => $part_index,
      );
    }
  }

  // Put the required contexts in order based on the path.
  ksort($required_context_info);

  // Convert required context info into objects.
  $required_contexts[$path] = array();
  foreach ($required_context_info as $context_position => $context_info) {
    $context = layout_create_context($context_info['plugin']);
    $context->required = TRUE;
    $context->usageType = LayoutContext::USAGE_TYPE_MENU;
    // String placeholders are not locked, allowing a new value to be set.
    $context->locked = $context_info['plugin'] !== 'string';
    $context->position = $context_position;
    $context->plugin = $context_info['plugin'];
    $required_contexts[$path][$context_position] = $context;
  }

  return $required_contexts[$path];
}

/**
 * Returns the current user account context, which is always available.
 *
 * @return EntityLayoutContext
 *   The layout context for the current user account.
 *
 * @since 1.17.5 Function added.
 */
function layout_current_user_context() {
  $current_user_context = layout_create_context('user', array(
    'name' => 'current_user',
    'label' => t('Logged-in user account'),
    'locked' => TRUE,
    'usageType' => LayoutContext::USAGE_TYPE_SYSTEM,
  ));
  $current_user_context->setData($GLOBALS['user']);

  return $current_user_context;
}

/**
 * Determine if a block has the necessary contexts.
 *
 * @param Layout $layout
 *   The layout on which the specified block will be displayed.
 * @param string $block_module
 *   The module that provides the block to be checked.
 * @param string $block_delta
 *   The identifier for the block within hook_block_info().
 *
 * @return bool
 *   TRUE if the block has required contexts. FALSE otherwise.
 */
function layout_block_has_required_contexts(Layout $layout, $block_module, $block_delta) {
  $block_info = module_invoke($block_module, 'block_info');
  $required_contexts = array();

  if (isset($block_info[$block_delta]['required contexts'])) {
    $required_contexts = $block_info[$block_delta]['required contexts'];
  }

  $available_contexts = $layout->getContexts();

  foreach ($required_contexts as $key => $required_context_plugin_name) {
    foreach ($available_contexts as $context) {
      if ($context->isA($required_context_plugin_name)) {
        // Matching context available, remove from required list.
        unset($required_contexts[$key]);
      }
    }
  }

  // If there are no missing contexts, all required contexts are available.
  return empty($required_contexts);
}

/**
 * Helper function for setting contexts on a layout handler.
 *
 * @param array $contexts
 *   An array of contexts that will be set by reference if all required contexts
 *   are found.
 * @param LayoutContext[] $all_contexts
 *   The full array of contexts on an entire layout, from which the required
 *   contexts will be selected.
 * @param array $required_contexts
 *   The array of context keys and types that need to be selected from
 *   the $all_contexts array and populated into the $contexts array.
 * @param array $context_settings
 *   If a plugin has multiple contexts, a user may select which context should
 *   be used. This array will be keyed by the plugin's required context keys,
 *   with the values being the overall layout's context keys.
 *
 * @return bool
 *   TRUE if all contexts were set on the Layout. If a requested context is not
 *   available, FALSE will be returned and no contexts will be set at all.
 */
function layout_set_handler_contexts(array &$contexts, array $all_contexts, array $required_contexts, array $context_settings) {
  foreach ($required_contexts as $required_context_key => $context_type) {
    // Use the configured context if available.
    if (isset($context_settings[$required_context_key])) {
      $layout_context_key = $context_settings[$required_context_key];
      if (isset($all_contexts[$layout_context_key]) && ($all_contexts[$layout_context_key]->isA($context_type))) {
        $contexts[$required_context_key] = $all_contexts[$layout_context_key];
        continue;
      }
    }

    // Otherwise use the first context that matches the right type.
    foreach ($all_contexts as $layout_context) {
      if ($layout_context->isA($context_type)) {
        $contexts[$required_context_key] = $layout_context;
        continue 2;
      }
    }

    // If we reach here, no matching required context was found, empty all
    // contexts to prevent partial functionality and return FALSE.
    $contexts = array();
    return FALSE;
  }

  // All required contexts populated successfully.
  return TRUE;
}

/**
 * Implements hook_modules_uninstalled().
 *
 * Deletes all blocks provided by a module when that module is uninstalled.
 */
function layout_modules_uninstalled($modules) {
  $layouts = layout_load_all();
  foreach ($modules as $module) {
    foreach ($layouts as $layout) {
      $blocks_to_remove = array();

      foreach ($layout->content as $uuid => $block) {
        if ($block->module == $module) {
          $blocks_to_remove[] = $uuid;
        }
      }

      if ($blocks_to_remove) {
        foreach ($blocks_to_remove as $uuid_to_remove) {
          $layout->removeBlock($uuid_to_remove);
        }
        $layout->save();
      }
    }
  }
}

/**
 * Gets the title description for the current layout.
 *
 * @param Layout $layout
 *   Full layout object.
 *
 * @return $description
 *   Description of title source.
 */
function layout_get_title_description(Layout $layout) {
  $source = $layout->settings['title_display'];
  switch ($source) {
    case LAYOUT_TITLE_DEFAULT:
      $description = t('Default page title');
      break;
    case LAYOUT_TITLE_CUSTOM:
      $description = t('Custom page title: %title', array('%title' => $layout->settings['title']));
      break;
    case LAYOUT_TITLE_BLOCK:
      $all_blocks = layout_get_block_info();
      if (!empty($layout->settings['title_block'])) {
        $uuid = $layout->settings['title_block'];
        $title_block = $layout->content[$uuid];
        $description = t('Title copied from the %block block', array('%block' => $all_blocks[$title_block->module][$title_block->delta]['info']));
      }
      break;
    case LAYOUT_TITLE_NONE:
      $description = t('No title');
      break;
  }

  return $description;
}

/**
 * Store changes to a flexible layout template in the temporary store.
 *
 * @param LayoutFlexibleTemplate $flexible_template
 *   The loaded flexible template object.
 */
function layout_flexible_tempstore_set(LayoutFlexibleTemplate $flexible_template) {
  tempstore_set('layout.flexible', $flexible_template->name, $flexible_template, 604800);
}

/**
 * Get a flexible template currently being edited from the tempstore.
 *
 * If a template is not yet being edited, the template will be loaded from
 * configuration.
 *
 * @param string $flexible_template_name
 *   The machine name of the flexible template to load.
 *
 * @return LayoutFlexibleTemplate
 *   The flexible template object.
 */
function layout_flexible_tempstore_load($flexible_template_name = NULL) {
  if (!$flexible_template_name) {
    return new LayoutFlexibleTemplate();
  }

  $caches = &backdrop_static(__FUNCTION__, array());
  if (!isset($caches[$flexible_template_name])) {
    if (!$item = tempstore_get('layout.flexible', $flexible_template_name)) {
      $item = layout_flexible_template_load($flexible_template_name);
    }
    $caches[$flexible_template_name] = $item;
  }

  return $caches[$flexible_template_name];
}

/**
 * Load an individual flexible template.
 *
 * @param string $flexible_template_name
 *   The machine name of the template to load.
 *
 * @return LayoutFlexibleTemplate|false
 */
function layout_flexible_template_load($flexible_template_name = NULL) {
  $all_templates = layout_flexible_template_load_all();
  if (isset($all_templates[$flexible_template_name])) {
    return $all_templates[$flexible_template_name];
  }
  else {
    return FALSE;
  }
}

/**
 * Load all flexible templates.
 *
 * @return LayoutFlexibleTemplate[]
 */
function layout_flexible_template_load_all() {
  $templates = &backdrop_static(__FUNCTION__, array());

  if (empty($templates)) {
    $cache = cache()->get('layout:flexible:config');
    if ($cache && $cache->data) {
      $configs = $cache->data;
    }
    else {
      $configs = array();
      $config_names = config_get_names_with_prefix('layout.flexible.');
      foreach ($config_names as $config_file) {
        $config = config($config_file);
        $data = $config->get();
        $configs[$data['name']] = $data;
      }

      cache()->set('layout:flexible:config', $configs);
    }

    foreach ($configs as $template_name => $config) {
      $templates[$template_name] = new LayoutFlexibleTemplate($config);
    }
  }

  return $templates;
}

/**
 * Implements hook_layout_template_info().
 */
function layout_layout_template_info() {
  $layouts = array();
  $styles = layout_flexible_row_styles();

  $flexible_templates = layout_flexible_template_load_all();
  foreach ($flexible_templates as $flexible_template) {
    $layouts[$flexible_template->name] = array(
      'title' => $flexible_template->title,
      'regions' => array(),
      'default region' => '',
      'template' => 'layout--flexible',
      'flexible' => TRUE,
      'type' => 'layout',
      'path' => 'templates',
      'preview' => 'flexible_template.png',
      'libraries' => array('bootstrap4-gs'),
    );

    foreach ($flexible_template->rows as $row_name => $region) {
      $region_style = $styles[$region['contains']];
      for ($i = 0; $i < $region_style['region_count']; $i++) {
        if (!empty($region['region_names']['region_' . $i]['label'])) {
          $region_name = $region['region_names']['region_' . $i]['label'];
        }
        else {
          $region_name = $row_name . ' ' . $i;
        }
        $layouts[$flexible_template->name]['regions'][$row_name . '--' . $i] = $region_name;
      }
    }
  }

  return $layouts;
}

/**
 * Implements deprecated hook_layout_info().
 *
 * This hook has been replaced by hook_layout_template_info.
 *
 * @deprecated since 1.30.0
 * @see layout_layout_template_info()
 * @see https://docs.backdropcms.org/change-records/hook_layout_info-renamed-to-hook_layout_template_info
 */
function layout_layout_info() {
  watchdog_deprecated_function('layout', __FUNCTION__);
  return layout_layout_template_info();
}

/**
 * Implements hook_layout_presave().
 */
function layout_layout_presave($layout) {
  if (!empty($layout->removed_blocks)) {
    foreach ($layout->removed_blocks as $uuid => $block) {
      // @todo: Follow-up for other block types with files/images.
      if (is_a($block, 'BlockHero')) {
        if (!empty($block->settings['image'])) {
          $image = file_load($block->settings['image']);
          if ($image) {
            file_usage_delete($image, 'layout', 'block', $image->fid);
          }
        }
      }
    }
  }
}

/**
 * Reset all caches provided by Layout module.
 */
function layout_flexible_reset_caches() {
  cache()->delete('layout:flexible:config');

  backdrop_static_reset('layout_flexible_template_load_all');
  backdrop_static_reset('layout_flexible_tempstore_load');
}

/**
 * Provides the default row styles.
 */
function layout_flexible_row_styles() {
  $styles = array(
    'region_12' => array(
      'split' => '100:0',
      'bootstrap' => '12:0',
      'region_count' => 1,
      'name' => t('One full-width region'),
    ),
    'region_10_2' => array(
      'split' => '83:17',
      'bootstrap' => '10:2',
      'region_count' => 2,
      'name' => t('Two regions') . (' 83% : 17%'),
    ),
    'region_9_3' => array(
      'split' => '75:25',
      'bootstrap' => '9:3',
      'region_count' => 2,
      'name' => t('Two regions') . (' 75% : 25%'),
    ),
    'region_8_4' => array(
      'split' => '67:33',
      'bootstrap' => '8:4',
      'region_count' => 2,
      'name' => t('Two regions') . (' 67% : 33%'),
    ),
    'region_6_6' => array(
      'split' => '50:50',
      'bootstrap' => '6:6',
      'region_count' => 2,
      'name' => t('Two regions') . (' 50% : 50%'),
    ),
    'region_4_8' => array(
      'split' => '33:67',
      'bootstrap' => '4:8',
      'region_count' => 2,
      'name' => t('Two regions') . (' 33% : 67%'),
    ),
    'region_3_9' => array(
      'split' => '25:75',
      'bootstrap' => '3:9',
      'region_count' => 2,
      'name' => t('Two regions') . (' 25% : 75%'),
    ),
    'region_2_10' => array(
      'split' => '17:83',
      'bootstrap' => '2:10',
      'region_count' => 2,
      'name' => t('Two regions') . (' 17% : 83%'),
    ),
    'region_4_4_4' => array(
      'split' => '33:33:33',
      'bootstrap' => '4:4:4',
      'region_count' => 3,
      'name' => t('Three regions') . (' 33% : 33% : 33%'),
    ),
    'region_2_8_2' => array(
      'split' => '17:67:17',
      'bootstrap' => '2:8:2',
      'region_count' => 3,
      'name' => t('Three regions') . (' 17% : 67% : 17%'),
    ),
    'region_2_2_8' => array(
      'split' => '17:17:67',
      'bootstrap' => '2:2:8',
      'region_count' => 3,
      'name' => t('Three regions') . (' 17% : 17% : 67%'),
    ),
    'region_8_2_2' => array(
      'split' => '67:17:17',
      'bootstrap' => '8:2:2',
      'region_count' => 3,
      'name' => t('Three regions') . (' 67% : 17% : 17%'),
    ),
    'region_3_6_3' => array(
      'split' => '25:50:25',
      'bootstrap' => '3:6:3',
      'region_count' => 3,
      'name' => t('Three regions') . (' 25% : 50% : 25%'),
    ),
    'region_3_3_6' => array(
      'split' => '25:25:50',
      'bootstrap' => '3:3:6',
      'region_count' => 3,
      'name' => t('Three regions') . (' 25% : 25% : 50%'),
    ),
    'region_6_3_3' => array(
      'split' => '50:25:25',
      'bootstrap' => '6:3:3',
      'region_count' => 3,
      'name' => t('Three regions') . (' 50% : 25% : 25%'),
    ),
    'region_4_2_6' => array(
      'split' => '33:17:50',
      'bootstrap' => '4:2:6',
      'region_count' => 3,
      'name' => t('Three regions') . (' 33% : 17% : 50%'),
    ),
    'region_4_6_2' => array(
      'split' => '33:50:17',
      'bootstrap' => '4:6:2',
      'region_count' => 3,
      'name' => t('Three regions') . (' 33% : 50% : 17%'),
    ),
    'region_2_6_4' => array(
      'split' => '17:50:33',
      'bootstrap' => '2:6:4',
      'region_count' => 3,
      'name' => t('Three regions') . (' 17% : 50% : 33%'),
    ),
    'region_2_4_6' => array(
      'split' => '17:33:50',
      'bootstrap' => '2:4:6',
      'region_count' => 3,
      'name' => t('Three regions') . (' 17% : 33% : 50%'),
    ),
    'region_6_2_4' => array(
      'split' => '50:17:33',
      'bootstrap' => '6:2:4',
      'region_count' => 3,
      'name' => t('Three regions') . (' 50% : 17% : 33%'),
    ),
    'region_6_4_2' => array(
      'split' => '50:33:17',
      'bootstrap' => '6:4:2',
      'region_count' => 3,
      'name' => t('Three regions') . (' 50% : 33% : 17%'),
    ),
    'region_3_3_3_3' => array(
      'split' => '25:25:25:25',
      'bootstrap' => '3:3:3:3',
      'region_count' => 4,
      'name' => t('Four regions') . (' 25% : 25% : 25% : 25%'),
    ),
    'region_3_3_4_2' => array(
      'split' => '25:25:33:17',
      'bootstrap' => '3:3:4:2',
      'region_count' => 4,
      'name' => t('Four regions') . (' 25% : 25% : 33% : 17%'),
    ),
    'region_3_3_2_4' => array(
      'split' => '25:25:17:33',
      'bootstrap' => '3:3:2:4',
      'region_count' => 4,
      'name' => t('Four regions') . (' 25% : 25% : 17% : 33%'),
    ),
    'region_4_3_3_2' => array(
      'split' => '33:25:25:17',
      'bootstrap' => '4:3:3:2',
      'region_count' => 4,
      'name' => t('Four regions') . (' 33% : 25% : 25% : 17%'),
    ),
    'region_2_3_3_4' => array(
      'split' => '17:25:25:33',
      'bootstrap' => '2:3:3:4',
      'region_count' => 4,
      'name' => t('Four regions') . (' 17% : 25% : 25% : 33%'),
    ),
    'region_2_4_3_3' => array(
      'split' => '17:33:25:25',
      'bootstrap' => '2:4:3:3',
      'region_count' => 4,
      'name' => t('Four regions') . (' 17% : 33% : 25% : 25%'),
    ),
    'region_4_2_3_3' => array(
      'split' => '33:17:25:25',
      'bootstrap' => '4:2:3:3',
      'region_count' => 4,
      'name' => t('Four regions') . (' 33% : 17% : 25% : 25%'),
    ),
    'region_2_4_4_2' => array(
      'split' => '17:33:33:17',
      'bootstrap' => '2:4:4:2',
      'region_count' => 4,
      'name' => t('Four regions') . (' 17% : 33% : 33% : 17%'),
    ),
    'region_2_4_2_4' => array(
      'split' => '17:33:17:33',
      'bootstrap' => '2:4:2:4',
      'region_count' => 4,
      'name' => t('Four regions') . (' 17% : 33% : 17% : 33%'),
    ),
    'region_4_2_2_4' => array(
      'split' => '33:17:17:33',
      'bootstrap' => '4:2:2:4',
      'region_count' => 4,
      'name' => t('Four regions') . (' 33% : 17% : 17% : 33%'),
    ),
    'region_4_2_4_2' => array(
      'split' => '33:17:33:17',
      'bootstrap' => '4:2:4:2',
      'region_count' => 4,
      'name' => t('Four regions') . (' 33% : 17% : 33% : 17%'),
    ),
  );

  return $styles;
}

/**
 * Utility function to clean CSS for Layout UI.
 *
 * @param string $classes
 *  CSS classes, as entered into the Layout user interface.
 *
 * @return string
 *   String of sanitized classes separated by spaces.
 */
function _layout_clean_custom_css($classes = array()) {
  if (!empty($classes)) {
    $new_classes = explode(' ', $classes);
    foreach ($new_classes as $class) {
      $clean_classes[] = backdrop_clean_css_identifier($class, array());
    }

    $clean_classes = array_filter($clean_classes);
    return implode(' ', $clean_classes);
  }

  return '';
}

/**
 * Implements hook_field_delete_instance().
 */
function layout_field_delete_instance($instance) {
  cache('layout_path')->flush();
}
Functions

Name	Description
layout_autoload_info	Implements hook_autoload_info().
layout_block_has_required_contexts	Determine if a block has the necessary contexts.
layout_block_info	Implements hook_block_info().
layout_clear_layout_tempstore	Remove an item from the object cache.
layout_config_info	Implements hook_config_info().
layout_contextual_links_view_alter	Implements hook_contextual_links_view_alter()
layout_context_required_by_path	Given a path with placeholders (%), determine the required contexts.
layout_create_access	Helper function to create a Layout Access.
layout_create_context	Helper function to create a Layout Context.
layout_create_handler	Helper function to instantiate handlers when loading from config.
layout_create_relationship	Helper function to create a Layout Context.
layout_create_renderer	Helper function to create a Layout Renderer.
layout_current_user_context	Returns the current user account context, which is always available.
layout_entity_menu_title	Title callback: Returns a label for the action link to create bundle layouts.
layout_field_delete_instance	Implements hook_field_delete_instance().
layout_flexible_reset_caches	Reset all caches provided by Layout module.
layout_flexible_row_styles	Provides the default row styles.
layout_flexible_template_load	Load an individual flexible template.
layout_flexible_template_load_all	Load all flexible templates.
layout_flexible_tempstore_load	Get a flexible template currently being edited from the tempstore.
layout_flexible_tempstore_set	Store changes to a flexible layout template in the temporary store.
layout_flush_caches	Implements hook_flush_caches().
layout_get_access_info	Load all layout access information from modules.
layout_get_all_configs	Read all configuration files from disk of a particular layout type.
layout_get_block_info	Get information about all blocks or just a single one.
layout_get_context_info	Load all layout context information from modules.
layout_get_handler_name	Helper function to get a handler class name based on the plugin name.
layout_get_layout_by_path	Get the layout which is active based on a path or router item.
layout_get_layout_info Deprecated	Load the layout template information for a single layout template name.
layout_get_layout_template_info	Load the information of either a single layout template or all available layout templates.
layout_get_layout_tempstore	Get a layout or menu item currently being edited from the tempstore.
layout_get_path_layout_names	Get a list of layouts that share a particular path.
layout_get_relationship_info	Load all layout relationship information from modules.
layout_get_renderer_info	Load all layout renderer information from modules.
layout_get_style_info	Load all layout style information from modules.
layout_get_title_description	Gets the title description for the current layout.
layout_layout_api	Implements hook_layout_api().
layout_layout_info Deprecated	Implements deprecated hook_layout_info().
layout_layout_presave	Implements hook_layout_presave().
layout_layout_template_info	Implements hook_layout_template_info().
layout_library_info	Implements hook_library_info().
layout_load	Load an individual layout.
layout_load_all	Return an array of all layouts as fully loaded Layout objects.
layout_load_multiple	Load multiple layouts based on a particular criteria.
layout_load_multiple_by_path	Load all layouts at a given path.
layout_load_multiple_by_router_item	Load all layouts for a given router item and allow other modules to alter them and/or set their contexts.
layout_menu	Implements hook_menu().
layout_menu_item_load	Load an individual Layout menu item.
layout_menu_item_load_all	Return an array of all menu items as fully loaded LayoutMenuItem objects.
layout_menu_item_load_multiple	Load menu items by name.
layout_menu_item_load_multiple_by_path	Load an individual Layout menu item based on its path.
layout_modules_uninstalled	Implements hook_modules_uninstalled().
layout_page_access	Menu access callback; Check access for any Layout-provided page.
layout_page_menu_item	Create a menu item for Layout-provided pages.
layout_page_title	Menu title callback; Return the title for editing a layout.
layout_path_load	Menu loader callback; Convert %layout_path placeholders to loaded objects.
layout_permission	Implements hook_permission().
layout_provides_path	Check if a path is provided by Layout module, as in a custom layout path.
layout_relationships_get_relevant_info	Fetch all relevant relationships.
layout_reset_caches	Reset all caches provided by Layout module.
layout_route_handler	Route handler callback; Execute the current route item or wrap in a layout.
layout_set_handler_contexts	Helper function for setting contexts on a layout handler.
layout_set_layout_tempstore	Store changes to a layout or menu item in the temporary store.
layout_suppress	Suppress the layout.
layout_tempstore_block_load	Menu loader to load an individual block from a layout.
layout_tempstore_load	Menu loader callback to load a Layout cache object.
layout_tempstore_menu_item_load	Menu loader callback to load a Layout cache object.
layout_theme	Implements hook_theme()
_layout_clean_custom_css	Utility function to clean CSS for Layout UI.
_layout_get_all_info	Load layout-related information from modules.
_layout_include_files	Load all include files for modules that implement hook_layout_api().
Constants

Name	Description
BLOCK_DISABLED	Denotes that the block is disabled.
BLOCK_ENABLED	Denotes that the block is enabled.
LAYOUT_STORAGE_DEFAULT	Layout constant for module-defined layouts.
LAYOUT_STORAGE_NORMAL	Layouts constant for user-defined layouts.
LAYOUT_STORAGE_OVERRIDE	Layout constant for layouts that override module-defined presets.
LAYOUT_TITLE_BLOCK	Layout constant indicating the title of the layout comes from a block.
LAYOUT_TITLE_CUSTOM	Layout constant indicating the title of the layout is manually specified.
LAYOUT_TITLE_DEFAULT	Layout constant indicating the title of the layout is the default.
LAYOUT_TITLE_NONE	Layout constant indicating the title of the layout is not shown.