Skip to content
Snippets Groups Projects
Select Git revision
  • 4e2ee96d4c04fbee06abcd3d0bf84a7893792c7f
  • 11.x default protected
  • 11.2.x protected
  • 10.5.x protected
  • 10.6.x protected
  • 11.1.x protected
  • 10.4.x protected
  • 11.0.x protected
  • 10.3.x protected
  • 7.x protected
  • 10.2.x protected
  • 10.1.x protected
  • 9.5.x protected
  • 10.0.x protected
  • 9.4.x protected
  • 9.3.x protected
  • 9.2.x protected
  • 9.1.x protected
  • 8.9.x protected
  • 9.0.x protected
  • 8.8.x protected
  • 10.5.1 protected
  • 11.2.2 protected
  • 11.2.1 protected
  • 11.2.0 protected
  • 10.5.0 protected
  • 11.2.0-rc2 protected
  • 10.5.0-rc1 protected
  • 11.2.0-rc1 protected
  • 10.4.8 protected
  • 11.1.8 protected
  • 10.5.0-beta1 protected
  • 11.2.0-beta1 protected
  • 11.2.0-alpha1 protected
  • 10.4.7 protected
  • 11.1.7 protected
  • 10.4.6 protected
  • 11.1.6 protected
  • 10.3.14 protected
  • 10.4.5 protected
  • 11.0.13 protected
41 results

story.module

Blame
  • Code owners
    Assign users and groups as approvers for specific file changes. Learn more.
    module.inc 38.69 KiB
    <?php
    
    /**
     * @file
     * API for loading and interacting with Drupal modules.
     */
    
    use Drupal\Component\Graph\Graph;
    
    /**
     * Load all the modules that have been enabled in the system table.
     *
     * @param $bootstrap
     *   Whether to load only the reduced set of modules loaded in "bootstrap mode"
     *   for cached pages. See bootstrap.inc.
     *
     * @return
     *   If $bootstrap is NULL, return a boolean indicating whether all modules
     *   have been loaded.
     */
    function module_load_all($bootstrap = FALSE) {
      // Already loaded code cannot be unloaded, but new modules may be added within
      // a request, which should be loaded as well.
      // Use the advanced drupal_static() pattern, since this is called very often.
      // @see theme()
      static $drupal_static_fast;
      if (!isset($drupal_static_fast)) {
        $drupal_static_fast['has_run'] = &drupal_static(__FUNCTION__, FALSE);
      }
      $has_run = &$drupal_static_fast['has_run'];
    
      if (isset($bootstrap)) {
        foreach (module_list(TRUE, $bootstrap) as $module) {
          drupal_load('module', $module);
        }
        // $has_run will be TRUE if $bootstrap is FALSE.
        $has_run = !$bootstrap;
      }
      return $has_run;
    }
    
    
    /**
     * Returns a list of currently active modules.
     *
     * Usually, this returns a list of all enabled modules. When called early on in
     * the bootstrap, it will return a list of vital modules only (those needed to
     * generate cached pages).
     *
     * All parameters to this function are optional and should generally not be
     * changed from their defaults.
     *
     * @param $refresh
     *   (optional) Whether to force the module list to be regenerated (such as
     *   after the administrator has changed the system settings). Defaults to
     *   FALSE.
     * @param $bootstrap_refresh
     *   (optional) When $refresh is TRUE, setting $bootstrap_refresh to TRUE forces
     *   the module list to be regenerated using the reduced set of modules loaded
     *   in "bootstrap mode" for cached pages. Otherwise, setting $refresh to TRUE
     *   generates the complete list of enabled modules.
     * @param $sort
     *   (optional) By default, modules are ordered by weight and module name. Set
     *   this option to TRUE to return a module list ordered only by module name.
     * @param $fixed_list
     *   (optional) If an array of module names is provided, this will override the
     *   module list with the given set of modules. This will persist until the next
     *   call with $refresh set to TRUE or with a new $fixed_list passed in. This
     *   parameter is primarily intended for internal use (e.g., in install.php and
     *   update.php).
     *
     * @return
     *   An associative array whose keys and values are the names of the modules in
     *   the list.
     */
    function module_list($refresh = FALSE, $bootstrap_refresh = FALSE, $sort = FALSE, $fixed_list = NULL) {
      // system_list() may be reset within a request, so the module list needs to be
      // reset, too.
      // Use the advanced drupal_static() pattern, since this is called very often.
      static $drupal_static_fast;
      if (!isset($drupal_static_fast)) {
        $drupal_static_fast['list'] = &drupal_static(__FUNCTION__ . ':list');
        $drupal_static_fast['sorted_list'] = &drupal_static(__FUNCTION__ . ':sorted_list');
      }
      $list = &$drupal_static_fast['list'];
      $sorted_list = &$drupal_static_fast['sorted_list'];
    
      if (!isset($list) || $refresh || isset($fixed_list)) {
        $list = array();
        $sorted_list = NULL;
        // The fixed list may be a completely empty array, thus check for isset().
        // Calling code may use this to empty out the module list entirely. For
        // example, unit tests need to ensure that no modules are invoked.
        if (isset($fixed_list)) {
          foreach ($fixed_list as $name => $module) {
            drupal_get_filename('module', $name, $module['filename']);
            $list[$name] = $name;
          }
        }
        else {
          if ($refresh) {
            // For the $refresh case, make sure that system_list() returns fresh
            // data.
            drupal_static_reset('system_list');
          }
          if ($bootstrap_refresh) {
            $list = system_list('bootstrap');
          }
          else {
            // Not using drupal_map_assoc() here as that requires common.inc.
            $list = array_keys(system_list('module_enabled'));
            $list = (!empty($list) ? array_combine($list, $list) : array());
          }
        }
      }
      if ($sort) {
        if (!isset($sorted_list)) {
          $sorted_list = $list;
          ksort($sorted_list);
        }
        return $sorted_list;
      }
      return $list;
    }
    
    /**
     * Build a list of bootstrap modules and enabled modules and themes.
     *
     * @param $type
     *   The type of list to return:
     *   - module_enabled: All enabled modules.
     *   - bootstrap: All enabled modules required for bootstrap.
     *   - theme: All themes.
     *
     * @return
     *   An associative array of modules or themes, keyed by name. For $type
     *   'bootstrap', the array values equal the keys. For $type 'module_enabled'
     *   or 'theme', the array values are objects representing the respective
     *   database row, with the 'info' property already unserialized.
     *
     * @see module_list()
     * @see list_themes()
     */
    function system_list($type) {
      $lists = &drupal_static(__FUNCTION__);
    
      // For bootstrap modules, attempt to fetch the list from cache if possible.
      // if not fetch only the required information to fire bootstrap hooks
      // in case we are going to serve the page from cache.
      if ($type == 'bootstrap') {
        if (isset($lists['bootstrap'])) {
          return $lists['bootstrap'];
        }
        if ($cached = cache('bootstrap')->get('bootstrap_modules')) {
          $bootstrap_list = $cached->data;
        }
        else {
          $bootstrap_list = db_query("SELECT name, filename FROM {system} WHERE status = 1 AND bootstrap = 1 AND type = 'module' ORDER BY weight ASC, name ASC")->fetchAllAssoc('name');
          cache('bootstrap')->set('bootstrap_modules', $bootstrap_list);
        }
        // To avoid a separate database lookup for the filepath, prime the
        // drupal_get_filename() static cache for bootstrap modules only.
        // The rest is stored separately to keep the bootstrap module cache small.
        foreach ($bootstrap_list as $module) {
          drupal_classloader_register($module->name, dirname($module->filename));
          drupal_get_filename('module', $module->name, $module->filename);
        }
        // We only return the module names here since module_list() doesn't need
        // the filename itself.
        $lists['bootstrap'] = array_keys($bootstrap_list);
      }
      // Otherwise build the list for enabled modules and themes.
      elseif (!isset($lists['module_enabled'])) {
        if ($cached = cache('bootstrap')->get('system_list')) {
          $lists = $cached->data;
        }
        else {
          $lists = array(
            'module_enabled' => array(),
            'theme' => array(),
            'filepaths' => array(),
          );
          // The module name (rather than the filename) is used as the fallback
          // weighting in order to guarantee consistent behavior across different
          // Drupal installations, which might have modules installed in different
          // locations in the file system. The ordering here must also be
          // consistent with the one used in module_implements().
          $result = db_query("SELECT * FROM {system} WHERE type = 'theme' OR (type = 'module' AND status = 1) ORDER BY weight ASC, name ASC");
          foreach ($result as $record) {
            $record->info = unserialize($record->info);
            // Build a list of all enabled modules.
            if ($record->type == 'module') {
              $lists['module_enabled'][$record->name] = $record;
            }
            // Build a list of themes.
            if ($record->type == 'theme') {
              $lists['theme'][$record->name] = $record;
            }
            // Build a list of filenames so drupal_get_filename can use it.
            if ($record->status) {
              $lists['filepaths'][] = array('type' => $record->type, 'name' => $record->name, 'filepath' => $record->filename);
            }
          }
          foreach ($lists['theme'] as $key => $theme) {
            if (!empty($theme->info['base theme'])) {
              // Make a list of the theme's base themes.
              $lists['theme'][$key]->base_themes = drupal_find_base_themes($lists['theme'], $key);
              // Don't proceed if there was a problem with the root base theme.
              if (!current($lists['theme'][$key]->base_themes)) {
                continue;
              }
              // Determine the root base theme.
              $base_key = key($lists['theme'][$key]->base_themes);
              // Add to the list of sub-themes for each of the theme's base themes.
              foreach (array_keys($lists['theme'][$key]->base_themes) as $base_theme) {
                $lists['theme'][$base_theme]->sub_themes[$key] = $lists['theme'][$key]->info['name'];
              }
              // Add the base theme's theme engine info.
              $lists['theme'][$key]->info['engine'] = $lists['theme'][$base_key]->info['engine'];
            }
            else {
              // A plain theme is its own base theme.
              $base_key = $key;
            }
            // Set the theme engine prefix.
            $lists['theme'][$key]->prefix = ($lists['theme'][$key]->info['engine'] == 'theme') ? $base_key : $lists['theme'][$key]->info['engine'];
          }
          cache('bootstrap')->set('system_list', $lists);
        }
        // To avoid a separate database lookup for the filepath, prime the
        // drupal_get_filename() static cache with all enabled modules and themes.
        foreach ($lists['filepaths'] as $item) {
          drupal_get_filename($item['type'], $item['name'], $item['filepath']);
          drupal_classloader_register($item['name'], dirname($item['filepath']));
        }
      }
    
      return $lists[$type];
    }
    
    /**
     * Reset all system_list() caches.
     */
    function system_list_reset() {
      drupal_static_reset('system_list');
      drupal_static_reset('system_rebuild_module_data');
      drupal_static_reset('list_themes');
      cache('bootstrap')->deleteMultiple(array('bootstrap_modules', 'system_list'));
    }
    
    /**
     * Find dependencies any level deep and fill in required by information too.
     *
     * @param $files
     *   The array of filesystem objects used to rebuild the cache.
     *
     * @return
     *   The same array with the new keys for each module:
     *   - requires: An array with the keys being the modules that this module
     *     requires.
     *   - required_by: An array with the keys being the modules that will not work
     *     without this module.
     */
    function _module_build_dependencies($files) {
      foreach ($files as $filename => $file) {
        $graph[$file->name]['edges'] = array();
        if (isset($file->info['dependencies']) && is_array($file->info['dependencies'])) {
          foreach ($file->info['dependencies'] as $dependency) {
            $dependency_data = drupal_parse_dependency($dependency);
            $graph[$file->name]['edges'][$dependency_data['name']] = $dependency_data;
          }
        }
      }
      $graph_object = new Graph($graph);
      $graph = $graph_object->searchAndSort();
      foreach ($graph as $module => $data) {
        $files[$module]->required_by = isset($data['reverse_paths']) ? $data['reverse_paths'] : array();
        $files[$module]->requires = isset($data['paths']) ? $data['paths'] : array();
        $files[$module]->sort = $data['weight'];
      }
      return $files;
    }
    
    /**
     * Determine whether a given module exists.
     *
     * @param $module
     *   The name of the module (without the .module extension).
     *
     * @return
     *   TRUE if the module is both installed and enabled.
     */
    function module_exists($module) {
      $list = module_list();
      return isset($list[$module]);
    }
    
    /**
     * Load a module's installation hooks.
     *
     * @param $module
     *   The name of the module (without the .module extension).
     *
     * @return
     *   The name of the module's install file, if successful; FALSE otherwise.
     */
    function module_load_install($module) {
      // Make sure the installation API is available
      include_once DRUPAL_ROOT . '/core/includes/install.inc';
    
      return module_load_include('install', $module);
    }
    
    /**
     * Load a module include file.
     *
     * Examples:
     * @code
     *   // Load node.admin.inc from the node module.
     *   module_load_include('inc', 'node', 'node.admin');
     *   // Load content_types.inc from the node module.
     *   module_load_include('inc', 'node', 'content_types');
     * @endcode
     *
     * Do not use this function to load an install file, use module_load_install()
     * instead. Do not use this function in a global context since it requires
     * Drupal to be fully bootstrapped, use require_once DRUPAL_ROOT . '/path/file'
     * instead.
     *
     * @param $type
     *   The include file's type (file extension).
     * @param $module
     *   The module to which the include file belongs.
     * @param $name
     *   (optional) The base file name (without the $type extension). If omitted,
     *   $module is used; i.e., resulting in "$module.$type" by default.
     *
     * @return
     *   The name of the included file, if successful; FALSE otherwise.
     */
    function module_load_include($type, $module, $name = NULL) {
      if (!isset($name)) {
        $name = $module;
      }
    
      if (function_exists('drupal_get_path')) {
        $file = DRUPAL_ROOT . '/' . drupal_get_path('module', $module) . "/$name.$type";
        if (is_file($file)) {
          require_once $file;
          return $file;
        }
      }
      return FALSE;
    }
    
    /**
     * Load an include file for each of the modules that have been enabled in
     * the system table.
     */
    function module_load_all_includes($type, $name = NULL) {
      $modules = module_list();
      foreach ($modules as $module) {
        module_load_include($type, $module, $name);
      }
    }
    
    /**
     * Enables or installs a given list of modules.
     *
     * Definitions:
     * - "Enabling" is the process of activating a module for use by Drupal.
     * - "Disabling" is the process of deactivating a module.
     * - "Installing" is the process of enabling it for the first time or after it
     *   has been uninstalled.
     * - "Uninstalling" is the process of removing all traces of a module.
     *
     * Order of events:
     * - Gather and add module dependencies to $module_list (if applicable).
     * - For each module that is being enabled:
     *   - Install module schema and update system registries and caches.
     *   - If the module is being enabled for the first time or had been
     *     uninstalled, invoke hook_install() and add it to the list of installed
     *     modules.
     *   - Invoke hook_enable().
     * - Invoke hook_modules_installed().
     * - Invoke hook_modules_enabled().
     *
     * @param $module_list
     *   An array of module names.
     * @param $enable_dependencies
     *   If TRUE, dependencies will automatically be added and enabled in the
     *   correct order. This incurs a significant performance cost, so use FALSE
     *   if you know $module_list is already complete and in the correct order.
     *
     * @return
     *   FALSE if one or more dependencies are missing, TRUE otherwise.
     *
     * @see hook_install()
     * @see hook_enable()
     * @see hook_modules_installed()
     * @see hook_modules_enabled()
     */
    function module_enable($module_list, $enable_dependencies = TRUE) {
      if ($enable_dependencies) {
        // Get all module data so we can find dependencies and sort.
        $module_data = system_rebuild_module_data();
        // Create an associative array with weights as values.
        $module_list = array_flip(array_values($module_list));
    
        while (list($module) = each($module_list)) {
          if (!isset($module_data[$module])) {
            // This module is not found in the filesystem, abort.
            return FALSE;
          }
          if ($module_data[$module]->status) {
            // Skip already enabled modules.
            unset($module_list[$module]);
            continue;
          }
          $module_list[$module] = $module_data[$module]->sort;
    
          // Add dependencies to the list, with a placeholder weight.
          // The new modules will be processed as the while loop continues.
          foreach (array_keys($module_data[$module]->requires) as $dependency) {
            if (!isset($module_list[$dependency])) {
              $module_list[$dependency] = 0;
            }
          }
        }
    
        if (!$module_list) {
          // Nothing to do. All modules already enabled.
          return TRUE;
        }
    
        // Sort the module list by pre-calculated weights.
        arsort($module_list);
        $module_list = array_keys($module_list);
      }
    
      // Required for module installation checks.
      include_once DRUPAL_ROOT . '/core/includes/install.inc';
    
      $modules_installed = array();
      $modules_enabled = array();
      foreach ($module_list as $module) {
        // Only process modules that are not already enabled.
        $existing = db_query("SELECT status FROM {system} WHERE type = :type AND name = :name", array(
          ':type' => 'module',
          ':name' => $module))
          ->fetchObject();
        if ($existing->status == 0) {
          // Load the module's code.
          drupal_load('module', $module);
          module_load_install($module);
    
          // Update the database and module list to reflect the new module. This
          // needs to be done first so that the module's hook implementations,
          // hook_schema() in particular, can be called while it is being
          // installed.
          db_update('system')
            ->fields(array('status' => 1))
            ->condition('type', 'module')
            ->condition('name', $module)
            ->execute();
          // Refresh the module list to include it.
          system_list_reset();
          module_list(TRUE);
          module_implements_reset();
          _system_update_bootstrap_status();
          // Update the registry to include it.
          registry_update();
          // Refresh the schema to include it.
          drupal_get_schema(NULL, TRUE);
          // Update the theme registry to include it.
          drupal_theme_rebuild();
    
          // Allow modules to react prior to the installation of a module.
          module_invoke_all('modules_preinstall', array($module));
    
          // Now install the module if necessary.
          if (drupal_get_installed_schema_version($module, TRUE) == SCHEMA_UNINSTALLED) {
            drupal_install_schema($module);
    
            // Set the schema version to the number of the last update provided
            // by the module.
            $versions = drupal_get_schema_versions($module);
            $version = $versions ? max($versions) : SCHEMA_INSTALLED;
    
            // Install default configuration of the module.
            config_install_default_config($module);
    
            // If the module has no current updates, but has some that were
            // previously removed, set the version to the value of
            // hook_update_last_removed().
            if ($last_removed = module_invoke($module, 'update_last_removed')) {
              $version = max($version, $last_removed);
            }
            drupal_set_installed_schema_version($module, $version);
            // Allow the module to perform install tasks.
            module_invoke($module, 'install');
            // Record the fact that it was installed.
            $modules_installed[] = $module;
            watchdog('system', '%module module installed.', array('%module' => $module), WATCHDOG_INFO);
          }
    
          // Allow modules to react prior to the enabling of a module.
          module_invoke_all('modules_preenable', array($module));
    
          // Enable the module.
          module_invoke($module, 'enable');
    
          // Record the fact that it was enabled.
          $modules_enabled[] = $module;
          watchdog('system', '%module module enabled.', array('%module' => $module), WATCHDOG_INFO);
        }
      }
    
      // If any modules were newly installed, invoke hook_modules_installed().
      if (!empty($modules_installed)) {
        module_invoke_all('modules_installed', $modules_installed);
      }
    
      // If any modules were newly enabled, invoke hook_modules_enabled().
      if (!empty($modules_enabled)) {
        module_invoke_all('modules_enabled', $modules_enabled);
      }
    
      return TRUE;
    }
    
    /**
     * Disable a given set of modules.
     *
     * @param $module_list
     *   An array of module names.
     * @param $disable_dependents
     *   If TRUE, dependent modules will automatically be added and disabled in the
     *   correct order. This incurs a significant performance cost, so use FALSE
     *   if you know $module_list is already complete and in the correct order.
     */
    function module_disable($module_list, $disable_dependents = TRUE) {
      if ($disable_dependents) {
        // Get all module data so we can find dependents and sort.
        $module_data = system_rebuild_module_data();
        // Create an associative array with weights as values.
        $module_list = array_flip(array_values($module_list));
    
        $profile = drupal_get_profile();
        while (list($module) = each($module_list)) {
          if (!isset($module_data[$module]) || !$module_data[$module]->status) {
            // This module doesn't exist or is already disabled, skip it.
            unset($module_list[$module]);
            continue;
          }
          $module_list[$module] = $module_data[$module]->sort;
    
          // Add dependent modules to the list, with a placeholder weight.
          // The new modules will be processed as the while loop continues.
          foreach ($module_data[$module]->required_by as $dependent => $dependent_data) {
            if (!isset($module_list[$dependent]) && $dependent != $profile) {
              $module_list[$dependent] = 0;
            }
          }
        }
    
        // Sort the module list by pre-calculated weights.
        asort($module_list);
        $module_list = array_keys($module_list);
      }
    
      $invoke_modules = array();
    
      foreach ($module_list as $module) {
        if (module_exists($module)) {
          module_load_install($module);
          module_invoke($module, 'disable');
          db_update('system')
            ->fields(array('status' => 0))
            ->condition('type', 'module')
            ->condition('name', $module)
            ->execute();
          $invoke_modules[] = $module;
          watchdog('system', '%module module disabled.', array('%module' => $module), WATCHDOG_INFO);
        }
      }
    
      if (!empty($invoke_modules)) {
        // Refresh the module list to exclude the disabled modules.
        system_list_reset();
        module_list(TRUE);
        module_implements_reset();
        // Invoke hook_modules_disabled before disabling modules,
        // so we can still call module hooks to get information.
        module_invoke_all('modules_disabled', $invoke_modules);
        // Update the registry to remove the newly-disabled module.
        registry_update();
        _system_update_bootstrap_status();
        // Update the theme registry to remove the newly-disabled module.
        drupal_theme_rebuild();
      }
    }
    
    /**
     * @defgroup hooks Hooks
     * @{
     * Allow modules to interact with the Drupal core.
     *
     * Drupal's module system is based on the concept of "hooks". A hook is a PHP
     * function that is named foo_bar(), where "foo" is the name of the module
     * (whose filename is thus foo.module) and "bar" is the name of the hook. Each
     * hook has a defined set of parameters and a specified result type.
     *
     * To extend Drupal, a module need simply implement a hook. When Drupal wishes
     * to allow intervention from modules, it determines which modules implement a
     * hook and calls that hook in all enabled modules that implement it.
     *
     * The available hooks to implement are explained here in the Hooks section of
     * the developer documentation. The string "hook" is used as a placeholder for
     * the module name in the hook definitions. For example, if the module file is
     * called example.module, then hook_help() as implemented by that module would
     * be defined as example_help().
     *
     * The example functions included are not part of the Drupal core, they are
     * just models that you can modify. Only the hooks implemented within modules
     * are executed when running Drupal.
     *
     * See also @link themeable the themeable group page. @endlink
     */
    
    /**
     * Determine whether a module implements a hook.
     *
     * @param $module
     *   The name of the module (without the .module extension).
     * @param $hook
     *   The name of the hook (e.g. "help" or "menu").
     *
     * @return
     *   TRUE if the module is both installed and enabled, and the hook is
     *   implemented in that module.
     */
    function module_hook($module, $hook) {
      $function = $module . '_' . $hook;
      if (function_exists($function)) {
        return TRUE;
      }
      // If the hook implementation does not exist, check whether it may live in an
      // optional include file registered via hook_hook_info().
      $hook_info = module_hook_info();
      if (isset($hook_info[$hook]['group'])) {
        module_load_include('inc', $module, $module . '.' . $hook_info[$hook]['group']);
        if (function_exists($function)) {
          return TRUE;
        }
      }
      return FALSE;
    }
    
    /**
     * Determine which modules are implementing a hook.
     *
     * @param $hook
     *   The name of the hook (e.g. "help" or "menu").
     * @param $sort
     *   By default, modules are ordered by weight and filename, settings this option
     *   to TRUE, module list will be ordered by module name.
     *
     * @return
     *   An array with the names of the modules which are implementing this hook.
     *
     * @see module_implements_write_cache()
     */
    function module_implements($hook, $sort = FALSE) {
      // Use the advanced drupal_static() pattern, since this is called very often.
      static $drupal_static_fast;
      if (!isset($drupal_static_fast)) {
        $drupal_static_fast['implementations'] = &drupal_static(__FUNCTION__);
      }
      $implementations = &$drupal_static_fast['implementations'];
    
      // Fetch implementations from cache.
      if (empty($implementations)) {
        $implementations = cache('bootstrap')->get('module_implements');
        if ($implementations === FALSE) {
          $implementations = array();
        }
        else {
          $implementations = $implementations->data;
        }
      }
    
      if (!isset($implementations[$hook])) {
        // The hook is not cached, so ensure that whether or not it has
        // implementations, that the cache is updated at the end of the request.
        $implementations['#write_cache'] = TRUE;
        $hook_info = module_hook_info();
        $implementations[$hook] = array();
        $list = module_list(FALSE, FALSE, $sort);
        foreach ($list as $module) {
          $include_file = isset($hook_info[$hook]['group']) && module_load_include('inc', $module, $module . '.' . $hook_info[$hook]['group']);
          // Since module_hook() may needlessly try to load the include file again,
          // function_exists() is used directly here.
          if (function_exists($module . '_' . $hook)) {
            $implementations[$hook][$module] = $include_file ? $hook_info[$hook]['group'] : FALSE;
          }
        }
        // Allow modules to change the weight of specific implementations but avoid
        // an infinite loop.
        if ($hook != 'module_implements_alter') {
          drupal_alter('module_implements', $implementations[$hook], $hook);
        }
      }
      else {
        foreach ($implementations[$hook] as $module => $group) {
          // If this hook implementation is stored in a lazy-loaded file, so include
          // that file first.
          if ($group) {
            module_load_include('inc', $module, "$module.$group");
          }
          // It is possible that a module removed a hook implementation without the
          // implementations cache being rebuilt yet, so we check whether the
          // function exists on each request to avoid undefined function errors.
          // Since module_hook() may needlessly try to load the include file again,
          // function_exists() is used directly here.
          if (!function_exists($module . '_' . $hook)) {
            // Clear out the stale implementation from the cache and force a cache
            // refresh to forget about no longer existing hook implementations.
            unset($implementations[$hook][$module]);
            $implementations['#write_cache'] = TRUE;
          }
        }
      }
    
      return array_keys($implementations[$hook]);
    }
    
    /**
     * Regenerate the stored list of hook implementations.
     */
    function module_implements_reset() {
      // We maintain a persistent cache of hook implementations in addition to the
      // static cache to avoid looping through every module and every hook on each
      // request. Benchmarks show that the benefit of this caching outweighs the
      // additional database hit even when using the default database caching
      // backend and only a small number of modules are enabled. The cost of the
      // cache('bootstrap')->get() is more or less constant and reduced further when
      // non-database caching backends are used, so there will be more significant
      // gains when a large number of modules are installed or hooks invoked, since
      // this can quickly lead to module_hook() being called several thousand times
      // per request.
      drupal_static_reset('module_implements');
      cache('bootstrap')->set('module_implements', array());
      drupal_static_reset('module_hook_info');
      drupal_static_reset('drupal_alter');
      cache('bootstrap')->delete('hook_info');
    }
    
    /**
     * Retrieve a list of what hooks are explicitly declared.
     */
    function module_hook_info() {
      // When this function is indirectly invoked from bootstrap_invoke_all() prior
      // to all modules being loaded, we do not want to cache an incomplete
      // hook_hook_info() result, so instead return an empty array. This requires
      // bootstrap hook implementations to reside in the .module file, which is
      // optimal for performance anyway.
      if (!module_load_all(NULL)) {
        return array();
      }
      $hook_info = &drupal_static(__FUNCTION__);
    
      if (!isset($hook_info)) {
        $hook_info = array();
        $cache = cache('bootstrap')->get('hook_info');
        if ($cache === FALSE) {
          // Rebuild the cache and save it.
          // We can't use module_invoke_all() here or it would cause an infinite
          // loop.
          foreach (module_list() as $module) {
            $function = $module . '_hook_info';
            if (function_exists($function)) {
              $result = $function();
              if (isset($result) && is_array($result)) {
                $hook_info = array_merge_recursive($hook_info, $result);
              }
            }
          }
          // We can't use drupal_alter() for the same reason as above.
          foreach (module_list() as $module) {
            $function = $module . '_hook_info_alter';
            if (function_exists($function)) {
              $function($hook_info);
            }
          }
          cache('bootstrap')->set('hook_info', $hook_info);
        }
        else {
          $hook_info = $cache->data;
        }
      }
    
      return $hook_info;
    }
    
    /**
     * Writes the hook implementation cache.
     *
     * @see module_implements()
     */
    function module_implements_write_cache() {
      $implementations = &drupal_static('module_implements');
      // Check whether we need to write the cache. We do not want to cache hooks
      // which are only invoked on HTTP POST requests since these do not need to be
      // optimized as tightly, and not doing so keeps the cache entry smaller.
      if (isset($implementations['#write_cache']) && ($_SERVER['REQUEST_METHOD'] == 'GET' || $_SERVER['REQUEST_METHOD'] == 'HEAD')) {
        unset($implementations['#write_cache']);
        cache('bootstrap')->set('module_implements', $implementations);
      }
    }
    
    /**
     * Invoke a hook in a particular module.
     *
     * @param $module
     *   The name of the module (without the .module extension).
     * @param $hook
     *   The name of the hook to invoke.
     * @param ...
     *   Arguments to pass to the hook implementation.
     *
     * @return
     *   The return value of the hook implementation.
     */
    function module_invoke($module, $hook) {
      $args = func_get_args();
      // Remove $module and $hook from the arguments.
      unset($args[0], $args[1]);
      if (module_hook($module, $hook)) {
        return call_user_func_array($module . '_' . $hook, $args);
      }
    }
    
    /**
     * Invoke a hook in all enabled modules that implement it.
     *
     * @param $hook
     *   The name of the hook to invoke.
     * @param ...
     *   Arguments to pass to the hook.
     *
     * @return
     *   An array of return values of the hook implementations. If modules return
     *   arrays from their implementations, those are merged into one array.
     */
    function module_invoke_all($hook) {
      $args = func_get_args();
      // Remove $hook from the arguments.
      unset($args[0]);
      $return = array();
      foreach (module_implements($hook) as $module) {
        $function = $module . '_' . $hook;
        if (function_exists($function)) {
          $result = call_user_func_array($function, $args);
          if (isset($result) && is_array($result)) {
            $return = array_merge_recursive($return, $result);
          }
          elseif (isset($result)) {
            $return[] = $result;
          }
        }
      }
    
      return $return;
    }
    
    /**
     * @} End of "defgroup hooks".
     */
    
    /**
     * Array of modules required by core.
     */
    function drupal_required_modules() {
      $files = drupal_system_listing('/^' . DRUPAL_PHP_FUNCTION_PATTERN . '\.info$/', 'modules', 'name', 0);
      $required = array();
    
      // An install profile is required and one must always be loaded.
      $required[] = drupal_get_profile();
    
      foreach ($files as $name => $file) {
        $info = drupal_parse_info_file($file->uri);
        if (!empty($info) && !empty($info['required']) && $info['required']) {
          $required[] = $name;
        }
      }
    
      return $required;
    }
    
    /**
     * Hands off alterable variables to type-specific *_alter implementations.
     *
     * This dispatch function hands off the passed-in variables to type-specific
     * hook_TYPE_alter() implementations in modules. It ensures a consistent
     * interface for all altering operations.
     *
     * A maximum of 2 alterable arguments is supported. In case more arguments need
     * to be passed and alterable, modules provide additional variables assigned by
     * reference in the last $context argument:
     * @code
     *   $context = array(
     *     'alterable' => &$alterable,
     *     'unalterable' => $unalterable,
     *     'foo' => 'bar',
     *   );
     *   drupal_alter('mymodule_data', $alterable1, $alterable2, $context);
     * @endcode
     *
     * Note that objects are always passed by reference in PHP5. If it is absolutely
     * required that no implementation alters a passed object in $context, then an
     * object needs to be cloned:
     * @code
     *   $context = array(
     *     'unalterable_object' => clone $object,
     *   );
     *   drupal_alter('mymodule_data', $data, $context);
     * @endcode
     *
     * @param $type
     *   A string describing the type of the alterable $data. 'form', 'links',
     *   'node_content', and so on are several examples. Alternatively can be an
     *   array, in which case hook_TYPE_alter() is invoked for each value in the
     *   array, ordered first by module, and then for each module, in the order of
     *   values in $type. For example, when Form API is using drupal_alter() to
     *   execute both hook_form_alter() and hook_form_FORM_ID_alter()
     *   implementations, it passes array('form', 'form_' . $form_id) for $type.
     * @param $data
     *   The variable that will be passed to hook_TYPE_alter() implementations to be
     *   altered. The type of this variable depends on the value of the $type
     *   argument. For example, when altering a 'form', $data will be a structured
     *   array. When altering a 'profile', $data will be an object.
     * @param $context1
     *   (optional) An additional variable that is passed by reference.
     * @param $context2
     *   (optional) An additional variable that is passed by reference. If more
     *   context needs to be provided to implementations, then this should be an
     *   associative array as described above.
     */
    function drupal_alter($type, &$data, &$context1 = NULL, &$context2 = NULL) {
      // Use the advanced drupal_static() pattern, since this is called very often.
      static $drupal_static_fast;
      if (!isset($drupal_static_fast)) {
        $drupal_static_fast['functions'] = &drupal_static(__FUNCTION__);
      }
      $functions = &$drupal_static_fast['functions'];
    
      // Most of the time, $type is passed as a string, so for performance,
      // normalize it to that. When passed as an array, usually the first item in
      // the array is a generic type, and additional items in the array are more
      // specific variants of it, as in the case of array('form', 'form_FORM_ID').
      if (is_array($type)) {
        $cid = implode(',', $type);
        $extra_types = $type;
        $type = array_shift($extra_types);
        // Allow if statements in this function to use the faster isset() rather
        // than !empty() both when $type is passed as a string, or as an array with
        // one item.
        if (empty($extra_types)) {
          unset($extra_types);
        }
      }
      else {
        $cid = $type;
      }
    
      // Some alter hooks are invoked many times per page request, so statically
      // cache the list of functions to call, and on subsequent calls, iterate
      // through them quickly.
      if (!isset($functions[$cid])) {
        $functions[$cid] = array();
        $hook = $type . '_alter';
        $modules = module_implements($hook);
        if (!isset($extra_types)) {
          // For the more common case of a single hook, we do not need to call
          // function_exists(), since module_implements() returns only modules with
          // implementations.
          foreach ($modules as $module) {
            $functions[$cid][] = $module . '_' . $hook;
          }
        }
        else {
          // For multiple hooks, we need $modules to contain every module that
          // implements at least one of them.
          $extra_modules = array();
          foreach ($extra_types as $extra_type) {
            $extra_modules = array_merge($extra_modules, module_implements($extra_type . '_alter'));
          }
          // If any modules implement one of the extra hooks that do not implement
          // the primary hook, we need to add them to the $modules array in their
          // appropriate order. module_implements() can only return ordered
          // implementations of a single hook. To get the ordered implementations
          // of multiple hooks, we mimic the module_implements() logic of first
          // ordering by module_list(), and then calling
          // drupal_alter('module_implements').
          if (array_diff($extra_modules, $modules)) {
            // Merge the arrays and order by module_list().
            $modules = array_intersect(module_list(), array_merge($modules, $extra_modules));
            // Since module_implements() already took care of loading the necessary
            // include files, we can safely pass FALSE for the array values.
            $implementations = array_fill_keys($modules, FALSE);
            // Let modules adjust the order solely based on the primary hook. This
            // ensures the same module order regardless of whether this if block
            // runs. Calling drupal_alter() recursively in this way does not result
            // in an infinite loop, because this call is for a single $type, so we
            // won't end up in this code block again.
            drupal_alter('module_implements', $implementations, $hook);
            $modules = array_keys($implementations);
          }
          foreach ($modules as $module) {
            // Since $modules is a merged array, for any given module, we do not
            // know whether it has any particular implementation, so we need a
            // function_exists().
            $function = $module . '_' . $hook;
            if (function_exists($function)) {
              $functions[$cid][] = $function;
            }
            foreach ($extra_types as $extra_type) {
              $function = $module . '_' . $extra_type . '_alter';
              if (function_exists($function)) {
                $functions[$cid][] = $function;
              }
            }
          }
        }
        // Allow the theme to alter variables after the theme system has been
        // initialized.
        global $theme, $base_theme_info;
        if (isset($theme)) {
          $theme_keys = array();
          foreach ($base_theme_info as $base) {
            $theme_keys[] = $base->name;
          }
          $theme_keys[] = $theme;
          foreach ($theme_keys as $theme_key) {
            $function = $theme_key . '_' . $hook;
            if (function_exists($function)) {
              $functions[$cid][] = $function;
            }
            if (isset($extra_types)) {
              foreach ($extra_types as $extra_type) {
                $function = $theme_key . '_' . $extra_type . '_alter';
                if (function_exists($function)) {
                  $functions[$cid][] = $function;
                }
              }
            }
          }
        }
      }
    
      foreach ($functions[$cid] as $function) {
        $function($data, $context1, $context2);
      }
    }