Drupal PHP Cross Reference Content Management Systems

Source: /modules/system/system.api.php - 4780 lines - 193184 bytes - Summary - Text - Print

   1  <?php
   2  
   3  /**
   4   * @file
   5   * Hooks provided by Drupal core and the System module.
   6   */
   7  
   8  /**
   9   * @addtogroup hooks
  10   * @{
  11   */
  12  
  13  /**
  14   * Defines one or more hooks that are exposed by a module.
  15   *
  16   * Normally hooks do not need to be explicitly defined. However, by declaring a
  17   * hook explicitly, a module may define a "group" for it. Modules that implement
  18   * a hook may then place their implementation in either $module.module or in
  19   * $module.$group.inc. If the hook is located in $module.$group.inc, then that
  20   * file will be automatically loaded when needed.
  21   * In general, hooks that are rarely invoked and/or are very large should be
  22   * placed in a separate include file, while hooks that are very short or very
  23   * frequently called should be left in the main module file so that they are
  24   * always available.
  25   *
  26   * @return
  27   *   An associative array whose keys are hook names and whose values are an
  28   *   associative array containing:
  29   *   - group: A string defining the group to which the hook belongs. The module
  30   *     system will determine whether a file with the name $module.$group.inc
  31   *     exists, and automatically load it when required.
  32   *
  33   * See system_hook_info() for all hook groups defined by Drupal core.
  34   *
  35   * @see hook_hook_info_alter().
  36   */
  37  function hook_hook_info() {
  38    $hooks['token_info'] = array(
  39      'group' => 'tokens',
  40    );
  41    $hooks['tokens'] = array(
  42      'group' => 'tokens',
  43    );
  44    return $hooks;
  45  }
  46  
  47  /**
  48   * Alter information from hook_hook_info().
  49   *
  50   * @param $hooks
  51   *   Information gathered by module_hook_info() from other modules'
  52   *   implementations of hook_hook_info(). Alter this array directly.
  53   *   See hook_hook_info() for information on what this may contain.
  54   */
  55  function hook_hook_info_alter(&$hooks) {
  56    // Our module wants to completely override the core tokens, so make
  57    // sure the core token hooks are not found.
  58    $hooks['token_info']['group'] = 'mytokens';
  59    $hooks['tokens']['group'] = 'mytokens';
  60  }
  61  
  62  /**
  63   * Inform the base system and the Field API about one or more entity types.
  64   *
  65   * Inform the system about one or more entity types (i.e., object types that
  66   * can be loaded via entity_load() and, optionally, to which fields can be
  67   * attached).
  68   *
  69   * @return
  70   *   An array whose keys are entity type names and whose values identify
  71   *   properties of those types that the system needs to know about:
  72   *   - label: The human-readable name of the type.
  73   *   - controller class: The name of the class that is used to load the objects.
  74   *     The class has to implement the DrupalEntityControllerInterface interface.
  75   *     Leave blank to use the DrupalDefaultEntityController implementation.
  76   *   - base table: (used by DrupalDefaultEntityController) The name of the
  77   *     entity type's base table.
  78   *   - revision table: The name of the entity type's revision table (if any).
  79   *   - static cache: (used by DrupalDefaultEntityController) FALSE to disable
  80   *     static caching of entities during a page request. Defaults to TRUE.
  81   *   - field cache: (used by Field API loading and saving of field data) FALSE
  82   *     to disable Field API's persistent cache of field data. Only recommended
  83   *     if a higher level persistent cache is available for the entity type.
  84   *     Defaults to TRUE.
  85   *   - load hook: The name of the hook which should be invoked by
  86   *     DrupalDefaultEntityController:attachLoad(), for example 'node_load'.
  87   *   - uri callback: A function taking an entity as argument and returning the
  88   *     URI elements of the entity, e.g. 'path' and 'options'. The actual entity
  89   *     URI can be constructed by passing these elements to url().
  90   *   - label callback: (optional) A function taking an entity and an entity type
  91   *     as arguments and returning the label of the entity. The entity label is
  92   *     the main string associated with an entity; for example, the title of a
  93   *     node or the subject of a comment. If there is an entity object property
  94   *     that defines the label, use the 'label' element of the 'entity keys'
  95   *     return value component to provide this information (see below). If more
  96   *     complex logic is needed to determine the label of an entity, you can
  97   *     instead specify a callback function here, which will be called to
  98   *     determine the entity label. See also the entity_label() function, which
  99   *     implements this logic.
 100   *   - language callback: (optional) A function taking an entity and an entity
 101   *     type as arguments and returning a language code. In most situations, when
 102   *     needing to determine this value, inspecting a property named after the
 103   *     'language' element of the 'entity keys' should be enough. The language
 104   *     callback is meant to be used primarily for temporary alterations of the
 105   *     property value: entity-defining modules are encouraged to always define a
 106   *     language property, instead of using the callback as main entity language
 107   *     source. In fact not having a language property defined is likely to
 108   *     prevent an entity from being queried by language. Moreover, given that
 109   *     entity_language() is not necessarily used everywhere it would be
 110   *     appropriate, modules implementing the language callback should be aware
 111   *     that this might not be always called.
 112   *   - fieldable: Set to TRUE if you want your entity type to accept fields
 113   *     being attached to it.
 114   *   - translation: An associative array of modules registered as field
 115   *     translation handlers. Array keys are the module names, array values
 116   *     can be any data structure the module uses to provide field translation.
 117   *     Any empty value disallows the module to appear as a translation handler.
 118   *   - entity keys: An array describing how the Field API can extract the
 119   *     information it needs from the objects of the type. Elements:
 120   *     - id: The name of the property that contains the primary id of the
 121   *       entity. Every entity object passed to the Field API must have this
 122   *       property and its value must be numeric.
 123   *     - revision: The name of the property that contains the revision id of
 124   *       the entity. The Field API assumes that all revision ids are unique
 125   *       across all entities of a type. This entry can be omitted if the
 126   *       entities of this type are not versionable.
 127   *     - bundle: The name of the property that contains the bundle name for the
 128   *       entity. The bundle name defines which set of fields are attached to
 129   *       the entity (e.g. what nodes call "content type"). This entry can be
 130   *       omitted if this entity type exposes a single bundle (all entities have
 131   *       the same collection of fields). The name of this single bundle will be
 132   *       the same as the entity type.
 133   *     - label: The name of the property that contains the entity label. For
 134   *       example, if the entity's label is located in $entity->subject, then
 135   *       'subject' should be specified here. If complex logic is required to
 136   *       build the label, a 'label callback' should be defined instead (see
 137   *       the 'label callback' section above for details).
 138   *     - language: The name of the property, typically 'language', that contains
 139   *       the language code representing the language the entity has been created
 140   *       in. This value may be changed when editing the entity and represents
 141   *       the language its textual components are supposed to have. If no
 142   *       language property is available, the 'language callback' may be used
 143   *       instead. This entry can be omitted if the entities of this type are not
 144   *       language-aware.
 145   *   - bundle keys: An array describing how the Field API can extract the
 146   *     information it needs from the bundle objects for this type. This entry
 147   *     is required if the 'path' provided in the 'bundles'/'admin' section
 148   *     identifies the bundle using a named menu placeholder whose loader
 149   *     callback returns an object (e.g., $vocabulary for taxonomy terms, or
 150   *     $node_type for nodes). If the path does not include the bundle, or the
 151   *     bundle is just a string rather than an automatically loaded object, then
 152   *     this can be omitted. Elements:
 153   *     - bundle: The name of the property of the bundle object that contains
 154   *       the name of the bundle object.
 155   *   - bundles: An array describing all bundles for this object type. Keys are
 156   *     bundles machine names, as found in the objects' 'bundle' property
 157   *     (defined in the 'entity keys' entry above). Elements:
 158   *     - label: The human-readable name of the bundle.
 159   *     - uri callback: Same as the 'uri callback' key documented above for the
 160   *       entity type, but for the bundle only. When determining the URI of an
 161   *       entity, if a 'uri callback' is defined for both the entity type and
 162   *       the bundle, the one for the bundle is used.
 163   *     - admin: An array of information that allows Field UI pages to attach
 164   *       themselves to the existing administration pages for the bundle.
 165   *       Elements:
 166   *       - path: the path of the bundle's main administration page, as defined
 167   *         in hook_menu(). If the path includes a placeholder for the bundle,
 168   *         the 'bundle argument' and 'real path' keys below are required.
 169   *       - bundle argument: The position of the bundle placeholder in 'path', if
 170   *         any.
 171   *       - real path: The actual path (no placeholder) of the bundle's main
 172   *         administration page. This will be used to generate links.
 173   *       - access callback: As in hook_menu(). 'user_access' will be assumed if
 174   *         no value is provided.
 175   *       - access arguments: As in hook_menu().
 176   *   - view modes: An array describing the view modes for the entity type. View
 177   *     modes let entities be displayed differently depending on the context.
 178   *     For instance, a node can be displayed differently on its own page
 179   *     ('full' mode), on the home page or taxonomy listings ('teaser' mode), or
 180   *     in an RSS feed ('rss' mode). Modules taking part in the display of the
 181   *     entity (notably the Field API) can adjust their behavior depending on
 182   *     the requested view mode. An additional 'default' view mode is available
 183   *     for all entity types. This view mode is not intended for actual entity
 184   *     display, but holds default display settings. For each available view
 185   *     mode, administrators can configure whether it should use its own set of
 186   *     field display settings, or just replicate the settings of the 'default'
 187   *     view mode, thus reducing the amount of display configurations to keep
 188   *     track of. Keys of the array are view mode names. Each view mode is
 189   *     described by an array with the following key/value pairs:
 190   *     - label: The human-readable name of the view mode
 191   *     - custom settings: A boolean specifying whether the view mode should by
 192   *       default use its own custom field display settings. If FALSE, entities
 193   *       displayed in this view mode will reuse the 'default' display settings
 194   *       by default (e.g. right after the module exposing the view mode is
 195   *       enabled), but administrators can later use the Field UI to apply custom
 196   *       display settings specific to the view mode.
 197   *
 198   * @see entity_load()
 199   * @see hook_entity_info_alter()
 200   */
 201  function hook_entity_info() {
 202    $return = array(
 203      'node' => array(
 204        'label' => t('Node'),
 205        'controller class' => 'NodeController',
 206        'base table' => 'node',
 207        'revision table' => 'node_revision',
 208        'uri callback' => 'node_uri',
 209        'fieldable' => TRUE,
 210        'translation' => array(
 211          'locale' => TRUE,
 212        ),
 213        'entity keys' => array(
 214          'id' => 'nid',
 215          'revision' => 'vid',
 216          'bundle' => 'type',
 217          'language' => 'language',
 218        ),
 219        'bundle keys' => array(
 220          'bundle' => 'type',
 221        ),
 222        'bundles' => array(),
 223        'view modes' => array(
 224          'full' => array(
 225            'label' => t('Full content'),
 226            'custom settings' => FALSE,
 227          ),
 228          'teaser' => array(
 229            'label' => t('Teaser'),
 230            'custom settings' => TRUE,
 231          ),
 232          'rss' => array(
 233            'label' => t('RSS'),
 234            'custom settings' => FALSE,
 235          ),
 236        ),
 237      ),
 238    );
 239  
 240    // Search integration is provided by node.module, so search-related
 241    // view modes for nodes are defined here and not in search.module.
 242    if (module_exists('search')) {
 243      $return['node']['view modes'] += array(
 244        'search_index' => array(
 245          'label' => t('Search index'),
 246          'custom settings' => FALSE,
 247        ),
 248        'search_result' => array(
 249          'label' => t('Search result'),
 250          'custom settings' => FALSE,
 251        ),
 252      );
 253    }
 254  
 255    // Bundles must provide a human readable name so we can create help and error
 256    // messages, and the path to attach Field admin pages to.
 257    foreach (node_type_get_names() as $type => $name) {
 258      $return['node']['bundles'][$type] = array(
 259        'label' => $name,
 260        'admin' => array(
 261          'path' => 'admin/structure/types/manage/%node_type',
 262          'real path' => 'admin/structure/types/manage/' . str_replace('_', '-', $type),
 263          'bundle argument' => 4,
 264          'access arguments' => array('administer content types'),
 265        ),
 266      );
 267    }
 268  
 269    return $return;
 270  }
 271  
 272  /**
 273   * Alter the entity info.
 274   *
 275   * Modules may implement this hook to alter the information that defines an
 276   * entity. All properties that are available in hook_entity_info() can be
 277   * altered here.
 278   *
 279   * @param $entity_info
 280   *   The entity info array, keyed by entity name.
 281   *
 282   * @see hook_entity_info()
 283   */
 284  function hook_entity_info_alter(&$entity_info) {
 285    // Set the controller class for nodes to an alternate implementation of the
 286    // DrupalEntityController interface.
 287    $entity_info['node']['controller class'] = 'MyCustomNodeController';
 288  }
 289  
 290  /**
 291   * Act on entities when loaded.
 292   *
 293   * This is a generic load hook called for all entity types loaded via the
 294   * entity API.
 295   *
 296   * @param $entities
 297   *   The entities keyed by entity ID.
 298   * @param $type
 299   *   The type of entities being loaded (i.e. node, user, comment).
 300   */
 301  function hook_entity_load($entities, $type) {
 302    foreach ($entities as $entity) {
 303      $entity->foo = mymodule_add_something($entity, $type);
 304    }
 305  }
 306  
 307  /**
 308   * Act on an entity before it is about to be created or updated.
 309   *
 310   * @param $entity
 311   *   The entity object.
 312   * @param $type
 313   *   The type of entity being saved (i.e. node, user, comment).
 314   */
 315  function hook_entity_presave($entity, $type) {
 316    $entity->changed = REQUEST_TIME;
 317  }
 318  
 319  /**
 320   * Act on entities when inserted.
 321   *
 322   * @param $entity
 323   *   The entity object.
 324   * @param $type
 325   *   The type of entity being inserted (i.e. node, user, comment).
 326   */
 327  function hook_entity_insert($entity, $type) {
 328    // Insert the new entity into a fictional table of all entities.
 329    $info = entity_get_info($type);
 330    list($id) = entity_extract_ids($type, $entity);
 331    db_insert('example_entity')
 332      ->fields(array(
 333        'type' => $type,
 334        'id' => $id,
 335        'created' => REQUEST_TIME,
 336        'updated' => REQUEST_TIME,
 337      ))
 338      ->execute();
 339  }
 340  
 341  /**
 342   * Act on entities when updated.
 343   *
 344   * @param $entity
 345   *   The entity object.
 346   * @param $type
 347   *   The type of entity being updated (i.e. node, user, comment).
 348   */
 349  function hook_entity_update($entity, $type) {
 350    // Update the entity's entry in a fictional table of all entities.
 351    $info = entity_get_info($type);
 352    list($id) = entity_extract_ids($type, $entity);
 353    db_update('example_entity')
 354      ->fields(array(
 355        'updated' => REQUEST_TIME,
 356      ))
 357      ->condition('type', $type)
 358      ->condition('id', $id)
 359      ->execute();
 360  }
 361  
 362  /**
 363   * Act on entities when deleted.
 364   *
 365   * @param $entity
 366   *   The entity object.
 367   * @param $type
 368   *   The type of entity being deleted (i.e. node, user, comment).
 369   */
 370  function hook_entity_delete($entity, $type) {
 371    // Delete the entity's entry from a fictional table of all entities.
 372    $info = entity_get_info($type);
 373    list($id) = entity_extract_ids($type, $entity);
 374    db_delete('example_entity')
 375      ->condition('type', $type)
 376      ->condition('id', $id)
 377      ->execute();
 378  }
 379  
 380  /**
 381   * Alter or execute an EntityFieldQuery.
 382   *
 383   * @param EntityFieldQuery $query
 384   *   An EntityFieldQuery. One of the most important properties to be changed is
 385   *   EntityFieldQuery::executeCallback. If this is set to an existing function,
 386   *   this function will get the query as its single argument and its result
 387   *   will be the returned as the result of EntityFieldQuery::execute(). This can
 388   *   be used to change the behavior of EntityFieldQuery entirely. For example,
 389   *   the default implementation can only deal with one field storage engine, but
 390   *   it is possible to write a module that can query across field storage
 391   *   engines. Also, the default implementation presumes entities are stored in
 392   *   SQL, but the execute callback could instead query any other entity storage,
 393   *   local or remote.
 394   *
 395   *   Note the $query->altered attribute which is TRUE in case the query has
 396   *   already been altered once. This happens with cloned queries.
 397   *   If there is a pager, then such a cloned query will be executed to count
 398   *   all elements. This query can be detected by checking for
 399   *   ($query->pager && $query->count), allowing the driver to return 0 from
 400   *   the count query and disable the pager.
 401   */
 402  function hook_entity_query_alter($query) {
 403    $query->executeCallback = 'my_module_query_callback';
 404  }
 405  
 406  /**
 407   * Act on entities being assembled before rendering.
 408   *
 409   * @param $entity
 410   *   The entity object.
 411   * @param $type
 412   *   The type of entity being rendered (i.e. node, user, comment).
 413   * @param $view_mode
 414   *   The view mode the entity is rendered in.
 415   * @param $langcode
 416   *   The language code used for rendering.
 417   *
 418   * The module may add elements to $entity->content prior to rendering. The
 419   * structure of $entity->content is a renderable array as expected by
 420   * drupal_render().
 421   *
 422   * @see hook_entity_view_alter()
 423   * @see hook_comment_view()
 424   * @see hook_node_view()
 425   * @see hook_user_view()
 426   */
 427  function hook_entity_view($entity, $type, $view_mode, $langcode) {
 428    $entity->content['my_additional_field'] = array(
 429      '#markup' => $additional_field,
 430      '#weight' => 10,
 431      '#theme' => 'mymodule_my_additional_field',
 432    );
 433  }
 434  
 435  /**
 436   * Alter the results of ENTITY_view().
 437   *
 438   * This hook is called after the content has been assembled in a structured
 439   * array and may be used for doing processing which requires that the complete
 440   * entity content structure has been built.
 441   *
 442   * If a module wishes to act on the rendered HTML of the entity rather than the
 443   * structured content array, it may use this hook to add a #post_render
 444   * callback. Alternatively, it could also implement hook_preprocess_ENTITY().
 445   * See drupal_render() and theme() for details.
 446   *
 447   * @param $build
 448   *   A renderable array representing the entity content.
 449   * @param $type
 450   *   The type of entity being rendered (i.e. node, user, comment).
 451   *
 452   * @see hook_entity_view()
 453   * @see hook_comment_view_alter()
 454   * @see hook_node_view_alter()
 455   * @see hook_taxonomy_term_view_alter()
 456   * @see hook_user_view_alter()
 457   */
 458  function hook_entity_view_alter(&$build, $type) {
 459    if ($build['#view_mode'] == 'full' && isset($build['an_additional_field'])) {
 460      // Change its weight.
 461      $build['an_additional_field']['#weight'] = -10;
 462  
 463      // Add a #post_render callback to act on the rendered HTML of the entity.
 464      $build['#post_render'][] = 'my_module_node_post_render';
 465    }
 466  }
 467  
 468  /**
 469   * Change the view mode of an entity that is being displayed.
 470   *
 471   * @param string $view_mode
 472   *   The view_mode that is to be used to display the entity.
 473   * @param array $context
 474   *   Array with contextual information, including:
 475   *   - entity_type: The type of the entity that is being viewed.
 476   *   - entity: The entity object.
 477   *   - langcode: The langcode the entity is being viewed in.
 478   */
 479  function hook_entity_view_mode_alter(&$view_mode, $context) {
 480    // For nodes, change the view mode when it is teaser.
 481    if ($context['entity_type'] == 'node' && $view_mode == 'teaser') {
 482      $view_mode = 'my_custom_view_mode';
 483    }
 484  }
 485  
 486  /**
 487   * Define administrative paths.
 488   *
 489   * Modules may specify whether or not the paths they define in hook_menu() are
 490   * to be considered administrative. Other modules may use this information to
 491   * display those pages differently (e.g. in a modal overlay, or in a different
 492   * theme).
 493   *
 494   * To change the administrative status of menu items defined in another module's
 495   * hook_menu(), modules should implement hook_admin_paths_alter().
 496   *
 497   * @return
 498   *   An associative array. For each item, the key is the path in question, in
 499   *   a format acceptable to drupal_match_path(). The value for each item should
 500   *   be TRUE (for paths considered administrative) or FALSE (for non-
 501   *   administrative paths).
 502   *
 503   * @see hook_menu()
 504   * @see drupal_match_path()
 505   * @see hook_admin_paths_alter()
 506   */
 507  function hook_admin_paths() {
 508    $paths = array(
 509      'mymodule/*/add' => TRUE,
 510      'mymodule/*/edit' => TRUE,
 511    );
 512    return $paths;
 513  }
 514  
 515  /**
 516   * Redefine administrative paths defined by other modules.
 517   *
 518   * @param $paths
 519   *   An associative array of administrative paths, as defined by implementations
 520   *   of hook_admin_paths().
 521   *
 522   * @see hook_admin_paths()
 523   */
 524  function hook_admin_paths_alter(&$paths) {
 525    // Treat all user pages as administrative.
 526    $paths['user'] = TRUE;
 527    $paths['user/*'] = TRUE;
 528    // Treat the forum topic node form as a non-administrative page.
 529    $paths['node/add/forum'] = FALSE;
 530  }
 531  
 532  /**
 533   * Act on entities as they are being prepared for view.
 534   *
 535   * Allows you to operate on multiple entities as they are being prepared for
 536   * view. Only use this if attaching the data during the entity_load() phase
 537   * is not appropriate, for example when attaching other 'entity' style objects.
 538   *
 539   * @param $entities
 540   *   The entities keyed by entity ID.
 541   * @param $type
 542   *   The type of entities being loaded (i.e. node, user, comment).
 543   * @param $langcode
 544   *   The language to display the entity in.
 545   */
 546  function hook_entity_prepare_view($entities, $type, $langcode) {
 547    // Load a specific node into the user object for later theming.
 548    if ($type == 'user') {
 549      $nodes = mymodule_get_user_nodes(array_keys($entities));
 550      foreach ($entities as $uid => $entity) {
 551        $entity->user_node = $nodes[$uid];
 552      }
 553    }
 554  }
 555  
 556  /**
 557   * Perform periodic actions.
 558   *
 559   * Modules that require some commands to be executed periodically can
 560   * implement hook_cron(). The engine will then call the hook whenever a cron
 561   * run happens, as defined by the administrator. Typical tasks managed by
 562   * hook_cron() are database maintenance, backups, recalculation of settings
 563   * or parameters, automated mailing, and retrieving remote data.
 564   *
 565   * Short-running or non-resource-intensive tasks can be executed directly in
 566   * the hook_cron() implementation.
 567   *
 568   * Long-running tasks and tasks that could time out, such as retrieving remote
 569   * data, sending email, and intensive file tasks, should use the queue API
 570   * instead of executing the tasks directly. To do this, first define one or
 571   * more queues via hook_cron_queue_info(). Then, add items that need to be
 572   * processed to the defined queues.
 573   */
 574  function hook_cron() {
 575    // Short-running operation example, not using a queue:
 576    // Delete all expired records since the last cron run.
 577    $expires = variable_get('mymodule_cron_last_run', REQUEST_TIME);
 578    db_delete('mymodule_table')
 579      ->condition('expires', $expires, '>=')
 580      ->execute();
 581    variable_set('mymodule_cron_last_run', REQUEST_TIME);
 582  
 583    // Long-running operation example, leveraging a queue:
 584    // Fetch feeds from other sites.
 585    $result = db_query('SELECT * FROM {aggregator_feed} WHERE checked + refresh < :time AND refresh <> :never', array(
 586      ':time' => REQUEST_TIME,
 587      ':never' => AGGREGATOR_CLEAR_NEVER,
 588    ));
 589    $queue = DrupalQueue::get('aggregator_feeds');
 590    foreach ($result as $feed) {
 591      $queue->createItem($feed);
 592    }
 593  }
 594  
 595  /**
 596   * Declare queues holding items that need to be run periodically.
 597   *
 598   * While there can be only one hook_cron() process running at the same time,
 599   * there can be any number of processes defined here running. Because of
 600   * this, long running tasks are much better suited for this API. Items queued
 601   * in hook_cron() might be processed in the same cron run if there are not many
 602   * items in the queue, otherwise it might take several requests, which can be
 603   * run in parallel.
 604   *
 605   * @return
 606   *   An associative array where the key is the queue name and the value is
 607   *   again an associative array. Possible keys are:
 608   *   - 'worker callback': The name of the function to call. It will be called
 609   *     with one argument, the item created via DrupalQueue::createItem() in
 610   *     hook_cron().
 611   *   - 'time': (optional) How much time Drupal should spend on calling this
 612   *     worker in seconds. Defaults to 15.
 613   *
 614   * @see hook_cron()
 615   * @see hook_cron_queue_info_alter()
 616   */
 617  function hook_cron_queue_info() {
 618    $queues['aggregator_feeds'] = array(
 619      'worker callback' => 'aggregator_refresh',
 620      'time' => 60,
 621    );
 622    return $queues;
 623  }
 624  
 625  /**
 626   * Alter cron queue information before cron runs.
 627   *
 628   * Called by drupal_cron_run() to allow modules to alter cron queue settings
 629   * before any jobs are processesed.
 630   *
 631   * @param array $queues
 632   *   An array of cron queue information.
 633   *
 634   * @see hook_cron_queue_info()
 635   * @see drupal_cron_run()
 636   */
 637  function hook_cron_queue_info_alter(&$queues) {
 638    // This site has many feeds so let's spend 90 seconds on each cron run
 639    // updating feeds instead of the default 60.
 640    $queues['aggregator_feeds']['time'] = 90;
 641  }
 642  
 643  /**
 644   * Allows modules to declare their own Form API element types and specify their
 645   * default values.
 646   *
 647   * This hook allows modules to declare their own form element types and to
 648   * specify their default values. The values returned by this hook will be
 649   * merged with the elements returned by hook_form() implementations and so
 650   * can return defaults for any Form APIs keys in addition to those explicitly
 651   * mentioned below.
 652   *
 653   * Each of the form element types defined by this hook is assumed to have
 654   * a matching theme function, e.g. theme_elementtype(), which should be
 655   * registered with hook_theme() as normal.
 656   *
 657   * For more information about custom element types see the explanation at
 658   * http://drupal.org/node/169815.
 659   *
 660   * @return
 661   *  An associative array describing the element types being defined. The array
 662   *  contains a sub-array for each element type, with the machine-readable type
 663   *  name as the key. Each sub-array has a number of possible attributes:
 664   *  - "#input": boolean indicating whether or not this element carries a value
 665   *    (even if it's hidden).
 666   *  - "#process": array of callback functions taking $element, $form_state,
 667   *    and $complete_form.
 668   *  - "#after_build": array of callback functions taking $element and $form_state.
 669   *  - "#validate": array of callback functions taking $form and $form_state.
 670   *  - "#element_validate": array of callback functions taking $element and
 671   *    $form_state.
 672   *  - "#pre_render": array of callback functions taking $element and $form_state.
 673   *  - "#post_render": array of callback functions taking $element and $form_state.
 674   *  - "#submit": array of callback functions taking $form and $form_state.
 675   *  - "#title_display": optional string indicating if and how #title should be
 676   *    displayed, see theme_form_element() and theme_form_element_label().
 677   *
 678   * @see hook_element_info_alter()
 679   * @see system_element_info()
 680   */
 681  function hook_element_info() {
 682    $types['filter_format'] = array(
 683      '#input' => TRUE,
 684    );
 685    return $types;
 686  }
 687  
 688  /**
 689   * Alter the element type information returned from modules.
 690   *
 691   * A module may implement this hook in order to alter the element type defaults
 692   * defined by a module.
 693   *
 694   * @param $type
 695   *   All element type defaults as collected by hook_element_info().
 696   *
 697   * @see hook_element_info()
 698   */
 699  function hook_element_info_alter(&$type) {
 700    // Decrease the default size of textfields.
 701    if (isset($type['textfield']['#size'])) {
 702      $type['textfield']['#size'] = 40;
 703    }
 704  }
 705  
 706  /**
 707   * Perform cleanup tasks.
 708   *
 709   * This hook is run at the end of each page request. It is often used for
 710   * page logging and specialized cleanup. This hook MUST NOT print anything
 711   * because by the time it runs the response is already sent to the browser.
 712   *
 713   * Only use this hook if your code must run even for cached page views.
 714   * If you have code which must run once on all non-cached pages, use
 715   * hook_init() instead. That is the usual case. If you implement this hook
 716   * and see an error like 'Call to undefined function', it is likely that
 717   * you are depending on the presence of a module which has not been loaded yet.
 718   * It is not loaded because Drupal is still in bootstrap mode.
 719   *
 720   * @param $destination
 721   *   If this hook is invoked as part of a drupal_goto() call, then this argument
 722   *   will be a fully-qualified URL that is the destination of the redirect.
 723   */
 724  function hook_exit($destination = NULL) {
 725    db_update('counter')
 726      ->expression('hits', 'hits + 1')
 727      ->condition('type', 1)
 728      ->execute();
 729  }
 730  
 731  /**
 732   * Perform necessary alterations to the JavaScript before it is presented on
 733   * the page.
 734   *
 735   * @param $javascript
 736   *   An array of all JavaScript being presented on the page.
 737   *
 738   * @see drupal_add_js()
 739   * @see drupal_get_js()
 740   * @see drupal_js_defaults()
 741   */
 742  function hook_js_alter(&$javascript) {
 743    // Swap out jQuery to use an updated version of the library.
 744    $javascript['misc/jquery.js']['data'] = drupal_get_path('module', 'jquery_update') . '/jquery.js';
 745  }
 746  
 747  /**
 748   * Registers JavaScript/CSS libraries associated with a module.
 749   *
 750   * Modules implementing this return an array of arrays. The key to each
 751   * sub-array is the machine readable name of the library. Each library may
 752   * contain the following items:
 753   *
 754   * - 'title': The human readable name of the library.
 755   * - 'website': The URL of the library's web site.
 756   * - 'version': A string specifying the version of the library; intentionally
 757   *   not a float because a version like "1.2.3" is not a valid float. Use PHP's
 758   *   version_compare() to compare different versions.
 759   * - 'js': An array of JavaScript elements; each element's key is used as $data
 760   *   argument, each element's value is used as $options array for
 761   *   drupal_add_js(). To add library-specific (not module-specific) JavaScript
 762   *   settings, the key may be skipped, the value must specify
 763   *   'type' => 'setting', and the actual settings must be contained in a 'data'
 764   *   element of the value.
 765   * - 'css': Like 'js', an array of CSS elements passed to drupal_add_css().
 766   * - 'dependencies': An array of libraries that are required for a library. Each
 767   *   element is an array listing the module and name of another library. Note
 768   *   that all dependencies for each dependent library will also be added when
 769   *   this library is added.
 770   *
 771   * Registered information for a library should contain re-usable data only.
 772   * Module- or implementation-specific data and integration logic should be added
 773   * separately.
 774   *
 775   * @return
 776   *   An array defining libraries associated with a module.
 777   *
 778   * @see system_library()
 779   * @see drupal_add_library()
 780   * @see drupal_get_library()
 781   */
 782  function hook_library() {
 783    // Library One.
 784    $libraries['library-1'] = array(
 785      'title' => 'Library One',
 786      'website' => 'http://example.com/library-1',
 787      'version' => '1.2',
 788      'js' => array(
 789        drupal_get_path('module', 'my_module') . '/library-1.js' => array(),
 790      ),
 791      'css' => array(
 792        drupal_get_path('module', 'my_module') . '/library-2.css' => array(
 793          'type' => 'file',
 794          'media' => 'screen',
 795        ),
 796      ),
 797    );
 798    // Library Two.
 799    $libraries['library-2'] = array(
 800      'title' => 'Library Two',
 801      'website' => 'http://example.com/library-2',
 802      'version' => '3.1-beta1',
 803      'js' => array(
 804        // JavaScript settings may use the 'data' key.
 805        array(
 806          'type' => 'setting',
 807          'data' => array('library2' => TRUE),
 808        ),
 809      ),
 810      'dependencies' => array(
 811        // Require jQuery UI core by System module.
 812        array('system', 'ui'),
 813        // Require our other library.
 814        array('my_module', 'library-1'),
 815        // Require another library.
 816        array('other_module', 'library-3'),
 817      ),
 818    );
 819    return $libraries;
 820  }
 821  
 822  /**
 823   * Alters the JavaScript/CSS library registry.
 824   *
 825   * Allows certain, contributed modules to update libraries to newer versions
 826   * while ensuring backwards compatibility. In general, such manipulations should
 827   * only be done by designated modules, since most modules that integrate with a
 828   * certain library also depend on the API of a certain library version.
 829   *
 830   * @param $libraries
 831   *   The JavaScript/CSS libraries provided by $module. Keyed by internal library
 832   *   name and passed by reference.
 833   * @param $module
 834   *   The name of the module that registered the libraries.
 835   *
 836   * @see hook_library()
 837   */
 838  function hook_library_alter(&$libraries, $module) {
 839    // Update Farbtastic to version 2.0.
 840    if ($module == 'system' && isset($libraries['farbtastic'])) {
 841      // Verify existing version is older than the one we are updating to.
 842      if (version_compare($libraries['farbtastic']['version'], '2.0', '<')) {
 843        // Update the existing Farbtastic to version 2.0.
 844        $libraries['farbtastic']['version'] = '2.0';
 845        $libraries['farbtastic']['js'] = array(
 846          drupal_get_path('module', 'farbtastic_update') . '/farbtastic-2.0.js' => array(),
 847        );
 848      }
 849    }
 850  }
 851  
 852  /**
 853   * Alter CSS files before they are output on the page.
 854   *
 855   * @param $css
 856   *   An array of all CSS items (files and inline CSS) being requested on the page.
 857   *
 858   * @see drupal_add_css()
 859   * @see drupal_get_css()
 860   */
 861  function hook_css_alter(&$css) {
 862    // Remove defaults.css file.
 863    unset($css[drupal_get_path('module', 'system') . '/defaults.css']);
 864  }
 865  
 866  /**
 867   * Alter the commands that are sent to the user through the Ajax framework.
 868   *
 869   * @param $commands
 870   *   An array of all commands that will be sent to the user.
 871   *
 872   * @see ajax_render()
 873   */
 874  function hook_ajax_render_alter($commands) {
 875    // Inject any new status messages into the content area.
 876    $commands[] = ajax_command_prepend('#block-system-main .content', theme('status_messages'));
 877  }
 878  
 879  /**
 880   * Add elements to a page before it is rendered.
 881   *
 882   * Use this hook when you want to add elements at the page level. For your
 883   * additions to be printed, they have to be placed below a top level array key
 884   * of the $page array that has the name of a region of the active theme.
 885   *
 886   * By default, valid region keys are 'page_top', 'header', 'sidebar_first',
 887   * 'content', 'sidebar_second' and 'page_bottom'. To get a list of all regions
 888   * of the active theme, use system_region_list($theme). Note that $theme is a
 889   * global variable.
 890   *
 891   * If you want to alter the elements added by other modules or if your module
 892   * depends on the elements of other modules, use hook_page_alter() instead which
 893   * runs after this hook.
 894   *
 895   * @param $page
 896   *   Nested array of renderable elements that make up the page.
 897   *
 898   * @see hook_page_alter()
 899   * @see drupal_render_page()
 900   */
 901  function hook_page_build(&$page) {
 902    if (menu_get_object('node', 1)) {
 903      // We are on a node detail page. Append a standard disclaimer to the
 904      // content region.
 905      $page['content']['disclaimer'] = array(
 906        '#markup' => t('Acme, Inc. is not responsible for the contents of this sample code.'),
 907        '#weight' => 25,
 908      );
 909    }
 910  }
 911  
 912  /**
 913   * Alter a menu router item right after it has been retrieved from the database or cache.
 914   *
 915   * This hook is invoked by menu_get_item() and allows for run-time alteration of router
 916   * information (page_callback, title, and so on) before it is translated and checked for
 917   * access. The passed-in $router_item is statically cached for the current request, so this
 918   * hook is only invoked once for any router item that is retrieved via menu_get_item().
 919   *
 920   * Usually, modules will only want to inspect the router item and conditionally
 921   * perform other actions (such as preparing a state for the current request).
 922   * Note that this hook is invoked for any router item that is retrieved by
 923   * menu_get_item(), which may or may not be called on the path itself, so implementations
 924   * should check the $path parameter if the alteration should fire for the current request
 925   * only.
 926   *
 927   * @param $router_item
 928   *   The menu router item for $path.
 929   * @param $path
 930   *   The originally passed path, for which $router_item is responsible.
 931   * @param $original_map
 932   *   The path argument map, as contained in $path.
 933   *
 934   * @see menu_get_item()
 935   */
 936  function hook_menu_get_item_alter(&$router_item, $path, $original_map) {
 937    // When retrieving the router item for the current path...
 938    if ($path == $_GET['q']) {
 939      // ...call a function that prepares something for this request.
 940      mymodule_prepare_something();
 941    }
 942  }
 943  
 944  /**
 945   * Define menu items and page callbacks.
 946   *
 947   * This hook enables modules to register paths in order to define how URL
 948   * requests are handled. Paths may be registered for URL handling only, or they
 949   * can register a link to be placed in a menu (usually the Navigation menu). A
 950   * path and its associated information is commonly called a "menu router item".
 951   * This hook is rarely called (for example, when modules are enabled), and
 952   * its results are cached in the database.
 953   *
 954   * hook_menu() implementations return an associative array whose keys define
 955   * paths and whose values are an associative array of properties for each
 956   * path. (The complete list of properties is in the return value section below.)
 957   *
 958   * The definition for each path may include a page callback function, which is
 959   * invoked when the registered path is requested. If there is no other
 960   * registered path that fits the requested path better, any further path
 961   * components are passed to the callback function. For example, your module
 962   * could register path 'abc/def':
 963   * @code
 964   *   function mymodule_menu() {
 965   *     $items['abc/def'] = array(
 966   *       'page callback' => 'mymodule_abc_view',
 967   *     );
 968   *     return $items;
 969   *   }
 970   *
 971   *   function mymodule_abc_view($ghi = 0, $jkl = '') {
 972   *     // ...
 973   *   }
 974   * @endcode
 975   * When path 'abc/def' is requested, no further path components are in the
 976   * request, and no additional arguments are passed to the callback function (so
 977   * $ghi and $jkl would take the default values as defined in the function
 978   * signature). When 'abc/def/123/foo' is requested, $ghi will be '123' and
 979   * $jkl will be 'foo'. Note that this automatic passing of optional path
 980   * arguments applies only to page and theme callback functions.
 981   *
 982   * In addition to optional path arguments, the page callback and other callback
 983   * functions may specify argument lists as arrays. These argument lists may
 984   * contain both fixed/hard-coded argument values and integers that correspond
 985   * to path components. When integers are used and the callback function is
 986   * called, the corresponding path components will be substituted for the
 987   * integers. That is, the integer 0 in an argument list will be replaced with
 988   * the first path component, integer 1 with the second, and so on (path
 989   * components are numbered starting from zero). To pass an integer without it
 990   * being replaced with its respective path component, use the string value of
 991   * the integer (e.g., '1') as the argument value. This substitution feature
 992   * allows you to re-use a callback function for several different paths. For
 993   * example:
 994   * @code
 995   *   function mymodule_menu() {
 996   *     $items['abc/def'] = array(
 997   *       'page callback' => 'mymodule_abc_view',
 998   *       'page arguments' => array(1, 'foo'),
 999   *     );
1000   *     return $items;
1001   *   }
1002   * @endcode
1003   * When path 'abc/def' is requested, the page callback function will get 'def'
1004   * as the first argument and (always) 'foo' as the second argument.
1005   *
1006   * If a page callback function uses an argument list array, and its path is
1007   * requested with optional path arguments, then the list array's arguments are
1008   * passed to the callback function first, followed by the optional path
1009   * arguments. Using the above example, when path 'abc/def/bar/baz' is requested,
1010   * mymodule_abc_view() will be called with 'def', 'foo', 'bar' and 'baz' as
1011   * arguments, in that order.
1012   *
1013   * Special care should be taken for the page callback drupal_get_form(), because
1014   * your specific form callback function will always receive $form and
1015   * &$form_state as the first function arguments:
1016   * @code
1017   *   function mymodule_abc_form($form, &$form_state) {
1018   *     // ...
1019   *     return $form;
1020   *   }
1021   * @endcode
1022   * See @link form_api Form API documentation @endlink for details.
1023   *
1024   * Wildcards within paths also work with integer substitution. For example,
1025   * your module could register path 'my-module/%/edit':
1026   * @code
1027   *   $items['my-module/%/edit'] = array(
1028   *     'page callback' => 'mymodule_abc_edit',
1029   *     'page arguments' => array(1),
1030   *   );
1031   * @endcode
1032   * When path 'my-module/foo/edit' is requested, integer 1 will be replaced
1033   * with 'foo' and passed to the callback function. Note that wildcards may not
1034   * be used as the first component.
1035   *
1036   * Registered paths may also contain special "auto-loader" wildcard components
1037   * in the form of '%mymodule_abc', where the '%' part means that this path
1038   * component is a wildcard, and the 'mymodule_abc' part defines the prefix for a
1039   * load function, which here would be named mymodule_abc_load(). When a matching
1040   * path is requested, your load function will receive as its first argument the
1041   * path component in the position of the wildcard; load functions may also be
1042   * passed additional arguments (see "load arguments" in the return value
1043   * section below). For example, your module could register path
1044   * 'my-module/%mymodule_abc/edit':
1045   * @code
1046   *   $items['my-module/%mymodule_abc/edit'] = array(
1047   *     'page callback' => 'mymodule_abc_edit',
1048   *     'page arguments' => array(1),
1049   *   );
1050   * @endcode
1051   * When path 'my-module/123/edit' is requested, your load function
1052   * mymodule_abc_load() will be invoked with the argument '123', and should
1053   * load and return an "abc" object with internal id 123:
1054   * @code
1055   *   function mymodule_abc_load($abc_id) {
1056   *     return db_query("SELECT * FROM {mymodule_abc} WHERE abc_id = :abc_id", array(':abc_id' => $abc_id))->fetchObject();
1057   *   }
1058   * @endcode
1059   * This 'abc' object will then be passed into the callback functions defined
1060   * for the menu item, such as the page callback function mymodule_abc_edit()
1061   * to replace the integer 1 in the argument array. Note that a load function
1062   * should return FALSE when it is unable to provide a loadable object. For
1063   * example, the node_load() function for the 'node/%node/edit' menu item will
1064   * return FALSE for the path 'node/999/edit' if a node with a node ID of 999
1065   * does not exist. The menu routing system will return a 404 error in this case.
1066   *
1067   * You can also define a %wildcard_to_arg() function (for the example menu
1068   * entry above this would be 'mymodule_abc_to_arg()'). The _to_arg() function
1069   * is invoked to retrieve a value that is used in the path in place of the
1070   * wildcard. A good example is user.module, which defines
1071   * user_uid_optional_to_arg() (corresponding to the menu entry
1072   * 'tracker/%user_uid_optional'). This function returns the user ID of the
1073   * current user.
1074   *
1075   * The _to_arg() function will get called with three arguments:
1076   * - $arg: A string representing whatever argument may have been supplied by
1077   *   the caller (this is particularly useful if you want the _to_arg()
1078   *   function only supply a (default) value if no other value is specified,
1079   *   as in the case of user_uid_optional_to_arg().
1080   * - $map: An array of all path fragments (e.g. array('node','123','edit') for
1081   *   'node/123/edit').
1082   * - $index: An integer indicating which element of $map corresponds to $arg.
1083   *
1084   * _load() and _to_arg() functions may seem similar at first glance, but they
1085   * have different purposes and are called at different times. _load()
1086   * functions are called when the menu system is collecting arguments to pass
1087   * to the callback functions defined for the menu item. _to_arg() functions
1088   * are called when the menu system is generating links to related paths, such
1089   * as the tabs for a set of MENU_LOCAL_TASK items.
1090   *
1091   * You can also make groups of menu items to be rendered (by default) as tabs
1092   * on a page. To do that, first create one menu item of type MENU_NORMAL_ITEM,
1093   * with your chosen path, such as 'foo'. Then duplicate that menu item, using a
1094   * subdirectory path, such as 'foo/tab1', and changing the type to
1095   * MENU_DEFAULT_LOCAL_TASK to make it the default tab for the group. Then add
1096   * the additional tab items, with paths such as "foo/tab2" etc., with type
1097   * MENU_LOCAL_TASK. Example:
1098   * @code
1099   * // Make "Foo settings" appear on the admin Config page
1100   * $items['admin/config/system/foo'] = array(
1101   *   'title' => 'Foo settings',
1102   *   'type' => MENU_NORMAL_ITEM,
1103   *   // Page callback, etc. need to be added here.
1104   * );
1105   * // Make "Tab 1" the main tab on the "Foo settings" page
1106   * $items['admin/config/system/foo/tab1'] = array(
1107   *   'title' => 'Tab 1',
1108   *   'type' => MENU_DEFAULT_LOCAL_TASK,
1109   *   // Access callback, page callback, and theme callback will be inherited
1110   *   // from 'admin/config/system/foo', if not specified here to override.
1111   * );
1112   * // Make an additional tab called "Tab 2" on "Foo settings"
1113   * $items['admin/config/system/foo/tab2'] = array(
1114   *   'title' => 'Tab 2',
1115   *   'type' => MENU_LOCAL_TASK,
1116   *   // Page callback and theme callback will be inherited from
1117   *   // 'admin/config/system/foo', if not specified here to override.
1118   *   // Need to add access callback or access arguments.
1119   * );
1120   * @endcode
1121   *
1122   * @return
1123   *   An array of menu items. Each menu item has a key corresponding to the
1124   *   Drupal path being registered. The corresponding array value is an
1125   *   associative array that may contain the following key-value pairs:
1126   *   - "title": Required. The untranslated title of the menu item.
1127   *   - "title callback": Function to generate the title; defaults to t().
1128   *     If you require only the raw string to be output, set this to FALSE.
1129   *   - "title arguments": Arguments to send to t() or your custom callback,
1130   *     with path component substitution as described above.
1131   *   - "description": The untranslated description of the menu item.
1132   *   - "page callback": The function to call to display a web page when the user
1133   *     visits the path. If omitted, the parent menu item's callback will be used
1134   *     instead.
1135   *   - "page arguments": An array of arguments to pass to the page callback
1136   *     function, with path component substitution as described above.
1137   *   - "delivery callback": The function to call to package the result of the
1138   *     page callback function and send it to the browser. Defaults to
1139   *     drupal_deliver_html_page() unless a value is inherited from a parent menu
1140   *     item. Note that this function is called even if the access checks fail,
1141   *     so any custom delivery callback function should take that into account.
1142   *     See drupal_deliver_html_page() for an example.
1143   *   - "access callback": A function returning TRUE if the user has access
1144   *     rights to this menu item, and FALSE if not. It can also be a boolean
1145   *     constant instead of a function, and you can also use numeric values
1146   *     (will be cast to boolean). Defaults to user_access() unless a value is
1147   *     inherited from the parent menu item; only MENU_DEFAULT_LOCAL_TASK items
1148   *     can inherit access callbacks. To use the user_access() default callback,
1149   *     you must specify the permission to check as 'access arguments' (see
1150   *     below).
1151   *   - "access arguments": An array of arguments to pass to the access callback
1152   *     function, with path component substitution as described above. If the
1153   *     access callback is inherited (see above), the access arguments will be
1154   *     inherited with it, unless overridden in the child menu item.
1155   *   - "theme callback": (optional) A function returning the machine-readable
1156   *     name of the theme that will be used to render the page. If not provided,
1157   *     the value will be inherited from a parent menu item. If there is no
1158   *     theme callback, or if the function does not return the name of a current
1159   *     active theme on the site, the theme for this page will be determined by
1160   *     either hook_custom_theme() or the default theme instead. As a general
1161   *     rule, the use of theme callback functions should be limited to pages
1162   *     whose functionality is very closely tied to a particular theme, since
1163   *     they can only be overridden by modules which specifically target those
1164   *     pages in hook_menu_alter(). Modules implementing more generic theme
1165   *     switching functionality (for example, a module which allows the theme to
1166   *     be set dynamically based on the current user's role) should use
1167   *     hook_custom_theme() instead.
1168   *   - "theme arguments": An array of arguments to pass to the theme callback
1169   *     function, with path component substitution as described above.
1170   *   - "file": A file that will be included before the page callback is called;
1171   *     this allows page callback functions to be in separate files. The file
1172   *     should be relative to the implementing module's directory unless
1173   *     otherwise specified by the "file path" option. Does not apply to other
1174   *     callbacks (only page callback).
1175   *   - "file path": The path to the directory containing the file specified in
1176   *     "file". This defaults to the path to the module implementing the hook.
1177   *   - "load arguments": An array of arguments to be passed to each of the
1178   *     wildcard object loaders in the path, after the path argument itself.
1179   *     For example, if a module registers path node/%node/revisions/%/view
1180   *     with load arguments set to array(3), the '%node' in the path indicates
1181   *     that the loader function node_load() will be called with the second
1182   *     path component as the first argument. The 3 in the load arguments
1183   *     indicates that the fourth path component will also be passed to
1184   *     node_load() (numbering of path components starts at zero). So, if path
1185   *     node/12/revisions/29/view is requested, node_load(12, 29) will be called.
1186   *     There are also two "magic" values that can be used in load arguments.
1187   *     "%index" indicates the index of the wildcard path component. "%map"
1188   *     indicates the path components as an array. For example, if a module
1189   *     registers for several paths of the form 'user/%user_category/edit/*', all
1190   *     of them can use the same load function user_category_load(), by setting
1191   *     the load arguments to array('%map', '%index'). For instance, if the user
1192   *     is editing category 'foo' by requesting path 'user/32/edit/foo', the load
1193   *     function user_category_load() will be called with 32 as its first
1194   *     argument, the array ('user', 32, 'edit', 'foo') as the map argument,
1195   *     and 1 as the index argument (because %user_category is the second path
1196   *     component and numbering starts at zero). user_category_load() can then
1197   *     use these values to extract the information that 'foo' is the category
1198   *     being requested.
1199   *   - "weight": An integer that determines the relative position of items in
1200   *     the menu; higher-weighted items sink. Defaults to 0. Menu items with the
1201   *     same weight are ordered alphabetically.
1202   *   - "menu_name": Optional. Set this to a custom menu if you don't want your
1203   *     item to be placed in Navigation.
1204   *   - "context": (optional) Defines the context a tab may appear in. By
1205   *     default, all tabs are only displayed as local tasks when being rendered
1206   *     in a page context. All tabs that should be accessible as contextual links
1207   *     in page region containers outside of the parent menu item's primary page
1208   *     context should be registered using one of the following contexts:
1209   *     - MENU_CONTEXT_PAGE: (default) The tab is displayed as local task for the
1210   *       page context only.
1211   *     - MENU_CONTEXT_INLINE: The tab is displayed as contextual link outside of
1212   *       the primary page context only.
1213   *     Contexts can be combined. For example, to display a tab both on a page
1214   *     and inline, a menu router item may specify:
1215   *     @code
1216   *       'context' => MENU_CONTEXT_PAGE | MENU_CONTEXT_INLINE,
1217   *     @endcode
1218   *   - "tab_parent": For local task menu items, the path of the task's parent
1219   *     item; defaults to the same path without the last component (e.g., the
1220   *     default parent for 'admin/people/create' is 'admin/people').
1221   *   - "tab_root": For local task menu items, the path of the closest non-tab
1222   *     item; same default as "tab_parent".
1223   *   - "position": Position of the block ('left' or 'right') on the system
1224   *     administration page for this item.
1225   *   - "type": A bitmask of flags describing properties of the menu item.
1226   *     Many shortcut bitmasks are provided as constants in menu.inc:
1227   *     - MENU_NORMAL_ITEM: Normal menu items show up in the menu tree and can be
1228   *       moved/hidden by the administrator.
1229   *     - MENU_CALLBACK: Callbacks simply register a path so that the correct
1230   *       information is generated when the path is accessed.
1231   *     - MENU_SUGGESTED_ITEM: Modules may "suggest" menu items that the
1232   *       administrator may enable.
1233   *     - MENU_LOCAL_ACTION: Local actions are menu items that describe actions
1234   *       on the parent item such as adding a new user or block, and are
1235   *       rendered in the action-links list in your theme.
1236   *     - MENU_LOCAL_TASK: Local tasks are menu items that describe different
1237   *       displays of data, and are generally rendered as tabs.
1238   *     - MENU_DEFAULT_LOCAL_TASK: Every set of local tasks should provide one
1239   *       "default" task, which should display the same page as the parent item.
1240   *     If the "type" element is omitted, MENU_NORMAL_ITEM is assumed.
1241   *   - "options": An array of options to be passed to l() when generating a link
1242   *     from this menu item. Note that the "options" parameter has no effect on
1243   *     MENU_LOCAL_TASK, MENU_DEFAULT_LOCAL_TASK, and MENU_LOCAL_ACTION items.
1244   *
1245   * For a detailed usage example, see page_example.module.
1246   * For comprehensive documentation on the menu system, see
1247   * http://drupal.org/node/102338.
1248   */
1249  function hook_menu() {
1250    $items['example'] = array(
1251      'title' => 'Example Page',
1252      'page callback' => 'example_page',
1253      'access arguments' => array('access content'),
1254      'type' => MENU_SUGGESTED_ITEM,
1255    );
1256    $items['example/feed'] = array(
1257      'title' => 'Example RSS feed',
1258      'page callback' => 'example_feed',
1259      'access arguments' => array('access content'),
1260      'type' => MENU_CALLBACK,
1261    );
1262  
1263    return $items;
1264  }
1265  
1266  /**
1267   * Alter the data being saved to the {menu_router} table after hook_menu is invoked.
1268   *
1269   * This hook is invoked by menu_router_build(). The menu definitions are passed
1270   * in by reference. Each element of the $items array is one item returned
1271   * by a module from hook_menu. Additional items may be added, or existing items
1272   * altered.
1273   *
1274   * @param $items
1275   *   Associative array of menu router definitions returned from hook_menu().
1276   */
1277  function hook_menu_alter(&$items) {
1278    // Example - disable the page at node/add
1279    $items['node/add']['access callback'] = FALSE;
1280  }
1281  
1282  /**
1283   * Alter the data being saved to the {menu_links} table by menu_link_save().
1284   *
1285   * @param $item
1286   *   Associative array defining a menu link as passed into menu_link_save().
1287   *
1288   * @see hook_translated_menu_link_alter()
1289   */
1290  function hook_menu_link_alter(&$item) {
1291    // Make all new admin links hidden (a.k.a disabled).
1292    if (strpos($item['link_path'], 'admin') === 0 && empty($item['mlid'])) {
1293      $item['hidden'] = 1;
1294    }
1295    // Flag a link to be altered by hook_translated_menu_link_alter().
1296    if ($item['link_path'] == 'devel/cache/clear') {
1297      $item['options']['alter'] = TRUE;
1298    }
1299    // Flag a link to be altered by hook_translated_menu_link_alter(), but only
1300    // if it is derived from a menu router item; i.e., do not alter a custom
1301    // menu link pointing to the same path that has been created by a user.
1302    if ($item['link_path'] == 'user' && $item['module'] == 'system') {
1303      $item['options']['alter'] = TRUE;
1304    }
1305  }
1306  
1307  /**
1308   * Alter a menu link after it has been translated and before it is rendered.
1309   *
1310   * This hook is invoked from _menu_link_translate() after a menu link has been
1311   * translated; i.e., after dynamic path argument placeholders (%) have been
1312   * replaced with actual values, the user access to the link's target page has
1313   * been checked, and the link has been localized. It is only invoked if
1314   * $item['options']['alter'] has been set to a non-empty value (e.g., TRUE).
1315   * This flag should be set using hook_menu_link_alter().
1316   *
1317   * Implementations of this hook are able to alter any property of the menu link.
1318   * For example, this hook may be used to add a page-specific query string to all
1319   * menu links, or hide a certain link by setting:
1320   * @code
1321   *   'hidden' => 1,
1322   * @endcode
1323   *
1324   * @param $item
1325   *   Associative array defining a menu link after _menu_link_translate()
1326   * @param $map
1327   *   Associative array containing the menu $map (path parts and/or objects).
1328   *
1329   * @see hook_menu_link_alter()
1330   */
1331  function hook_translated_menu_link_alter(&$item, $map) {
1332    if ($item['href'] == 'devel/cache/clear') {
1333      $item['localized_options']['query'] = drupal_get_destination();
1334    }
1335  }
1336  
1337  /**
1338   * Inform modules that a menu link has been created.
1339   *
1340   * This hook is used to notify modules that menu items have been
1341   * created. Contributed modules may use the information to perform
1342   * actions based on the information entered into the menu system.
1343   *
1344   * @param $link
1345   *   Associative array defining a menu link as passed into menu_link_save().
1346   *
1347   * @see hook_menu_link_update()
1348   * @see hook_menu_link_delete()
1349   */
1350  function hook_menu_link_insert($link) {
1351    // In our sample case, we track menu items as editing sections
1352    // of the site. These are stored in our table as 'disabled' items.
1353    $record['mlid'] = $link['mlid'];
1354    $record['menu_name'] = $link['menu_name'];
1355    $record['status'] = 0;
1356    drupal_write_record('menu_example', $record);
1357  }
1358  
1359  /**
1360   * Inform modules that a menu link has been updated.
1361   *
1362   * This hook is used to notify modules that menu items have been
1363   * updated. Contributed modules may use the information to perform
1364   * actions based on the information entered into the menu system.
1365   *
1366   * @param $link
1367   *   Associative array defining a menu link as passed into menu_link_save().
1368   *
1369   * @see hook_menu_link_insert()
1370   * @see hook_menu_link_delete()
1371   */
1372  function hook_menu_link_update($link) {
1373    // If the parent menu has changed, update our record.
1374    $menu_name = db_query("SELECT menu_name FROM {menu_example} WHERE mlid = :mlid", array(':mlid' => $link['mlid']))->fetchField();
1375    if ($menu_name != $link['menu_name']) {
1376      db_update('menu_example')
1377        ->fields(array('menu_name' => $link['menu_name']))
1378        ->condition('mlid', $link['mlid'])
1379        ->execute();
1380    }
1381  }
1382  
1383  /**
1384   * Inform modules that a menu link has been deleted.
1385   *
1386   * This hook is used to notify modules that menu items have been
1387   * deleted. Contributed modules may use the information to perform
1388   * actions based on the information entered into the menu system.
1389   *
1390   * @param $link
1391   *   Associative array defining a menu link as passed into menu_link_save().
1392   *
1393   * @see hook_menu_link_insert()
1394   * @see hook_menu_link_update()
1395   */
1396  function hook_menu_link_delete($link) {
1397    // Delete the record from our table.
1398    db_delete('menu_example')
1399      ->condition('mlid', $link['mlid'])
1400      ->execute();
1401  }
1402  
1403  /**
1404   * Alter tabs and actions displayed on the page before they are rendered.
1405   *
1406   * This hook is invoked by menu_local_tasks(). The system-determined tabs and
1407   * actions are passed in by reference. Additional tabs or actions may be added,
1408   * or existing items altered.
1409   *
1410   * Each tab or action is an associative array containing:
1411   * - #theme: The theme function to use to render.
1412   * - #link: An associative array containing:
1413   *   - title: The localized title of the link.
1414   *   - href: The system path to link to.
1415   *   - localized_options: An array of options to pass to url().
1416   * - #active: Whether the link should be marked as 'active'.
1417   *
1418   * @param $data
1419   *   An associative array containing:
1420   *   - actions: An associative array containing:
1421   *     - count: The amount of actions determined by the menu system, which can
1422   *       be ignored.
1423   *     - output: A list of of actions, each one being an associative array
1424   *       as described above.
1425   *   - tabs: An indexed array (list) of tab levels (up to 2 levels), each
1426   *     containing an associative array:
1427   *     - count: The amount of tabs determined by the menu system. This value
1428   *       does not need to be altered if there is more than one tab.
1429   *     - output: A list of of tabs, each one being an associative array as
1430   *       described above.
1431   * @param $router_item
1432   *   The menu system router item of the page.
1433   * @param $root_path
1434   *   The path to the root item for this set of tabs.
1435   */
1436  function hook_menu_local_tasks_alter(&$data, $router_item, $root_path) {
1437    // Add an action linking to node/add to all pages.
1438    $data['actions']['output'][] = array(
1439      '#theme' => 'menu_local_task',
1440      '#link' => array(
1441        'title' => t('Add new content'),
1442        'href' => 'node/add',
1443        'localized_options' => array(
1444          'attributes' => array(
1445            'title' => t('Add new content'),
1446          ),
1447        ),
1448      ),
1449    );
1450  
1451    // Add a tab linking to node/add to all pages.
1452    $data['tabs'][0]['output'][] = array(
1453      '#theme' => 'menu_local_task',
1454      '#link' => array(
1455        'title' => t('Example tab'),
1456        'href' => 'node/add',
1457        'localized_options' => array(
1458          'attributes' => array(
1459            'title' => t('Add new content'),
1460          ),
1461        ),
1462      ),
1463      // Define whether this link is active. This can be omitted for
1464      // implementations that add links to pages outside of the current page
1465      // context.
1466      '#active' => ($router_item['path'] == $root_path),
1467    );
1468  }
1469  
1470  /**
1471   * Alter links in the active trail before it is rendered as the breadcrumb.
1472   *
1473   * This hook is invoked by menu_get_active_breadcrumb() and allows alteration
1474   * of the breadcrumb links for the current page, which may be preferred instead
1475   * of setting a custom breadcrumb via drupal_set_breadcrumb().
1476   *
1477   * Implementations should take into account that menu_get_active_breadcrumb()
1478   * subsequently performs the following adjustments to the active trail *after*
1479   * this hook has been invoked:
1480   * - The last link in $active_trail is removed, if its 'href' is identical to
1481   *   the 'href' of $item. This happens, because the breadcrumb normally does
1482   *   not contain a link to the current page.
1483   * - The (second to) last link in $active_trail is removed, if the current $item
1484   *   is a MENU_DEFAULT_LOCAL_TASK. This happens in order to do not show a link
1485   *   to the current page, when being on the path for the default local task;
1486   *   e.g. when being on the path node/%/view, the breadcrumb should not contain
1487   *   a link to node/%.
1488   *
1489   * Each link in the active trail must contain:
1490   * - title: The localized title of the link.
1491   * - href: The system path to link to.
1492   * - localized_options: An array of options to pass to url().
1493   *
1494   * @param $active_trail
1495   *   An array containing breadcrumb links for the current page.
1496   * @param $item
1497   *   The menu router item of the current page.
1498   *
1499   * @see drupal_set_breadcrumb()
1500   * @see menu_get_active_breadcrumb()
1501   * @see menu_get_active_trail()
1502   * @see menu_set_active_trail()
1503   */
1504  function hook_menu_breadcrumb_alter(&$active_trail, $item) {
1505    // Always display a link to the current page by duplicating the last link in
1506    // the active trail. This means that menu_get_active_breadcrumb() will remove
1507    // the last link (for the current page), but since it is added once more here,
1508    // it will appear.
1509    if (!drupal_is_front_page()) {
1510      $end = end($active_trail);
1511      if ($item['href'] == $end['href']) {
1512        $active_trail[] = $end;
1513      }
1514    }
1515  }
1516  
1517  /**
1518   * Alter contextual links before they are rendered.
1519   *
1520   * This hook is invoked by menu_contextual_links(). The system-determined
1521   * contextual links are passed in by reference. Additional links may be added
1522   * or existing links can be altered.
1523   *
1524   * Each contextual link must at least contain:
1525   * - title: The localized title of the link.
1526   * - href: The system path to link to.
1527   * - localized_options: An array of options to pass to url().
1528   *
1529   * @param $links
1530   *   An associative array containing contextual links for the given $root_path,
1531   *   as described above. The array keys are used to build CSS class names for
1532   *   contextual links and must therefore be unique for each set of contextual
1533   *   links.
1534   * @param $router_item
1535   *   The menu router item belonging to the $root_path being requested.
1536   * @param $root_path
1537   *   The (parent) path that has been requested to build contextual links for.
1538   *   This is a normalized path, which means that an originally passed path of
1539   *   'node/123' became 'node/%'.
1540   *
1541   * @see hook_contextual_links_view_alter()
1542   * @see menu_contextual_links()
1543   * @see hook_menu()
1544   * @see contextual_preprocess()
1545   */
1546  function hook_menu_contextual_links_alter(&$links, $router_item, $root_path) {
1547    // Add a link to all contextual links for nodes.
1548    if ($root_path == 'node/%') {
1549      $links['foo'] = array(
1550        'title' => t('Do fu'),
1551        'href' => 'foo/do',
1552        'localized_options' => array(
1553          'query' => array(
1554            'foo' => 'bar',
1555          ),
1556        ),
1557      );
1558    }
1559  }
1560  
1561  /**
1562   * Perform alterations before a page is rendered.
1563   *
1564   * Use this hook when you want to remove or alter elements at the page
1565   * level, or add elements at the page level that depend on an other module's
1566   * elements (this hook runs after hook_page_build().
1567   *
1568   * If you are making changes to entities such as forms, menus, or user
1569   * profiles, use those objects' native alter hooks instead (hook_form_alter(),
1570   * for example).
1571   *
1572   * The $page array contains top level elements for each block region:
1573   * @code
1574   *   $page['page_top']
1575   *   $page['header']
1576   *   $page['sidebar_first']
1577   *   $page['content']
1578   *   $page['sidebar_second']
1579   *   $page['page_bottom']
1580   * @endcode
1581   *
1582   * The 'content' element contains the main content of the current page, and its
1583   * structure will vary depending on what module is responsible for building the
1584   * page. Some legacy modules may not return structured content at all: their
1585   * pre-rendered markup will be located in $page['content']['main']['#markup'].
1586   *
1587   * Pages built by Drupal's core Node and Blog modules use a standard structure:
1588   *
1589   * @code
1590   *   // Node body.
1591   *   $page['content']['system_main']['nodes'][$nid]['body']
1592   *   // Array of links attached to the node (add comments, read more).
1593   *   $page['content']['system_main']['nodes'][$nid]['links']
1594   *   // The node object itself.
1595   *   $page['content']['system_main']['nodes'][$nid]['#node']
1596   *   // The results pager.
1597   *   $page['content']['system_main']['pager']
1598   * @endcode
1599   *
1600   * Blocks may be referenced by their module/delta pair within a region:
1601   * @code
1602   *   // The login block in the first sidebar region.
1603   *   $page['sidebar_first']['user_login']['#block'];
1604   * @endcode
1605   *
1606   * @param $page
1607   *   Nested array of renderable elements that make up the page.
1608   *
1609   * @see hook_page_build()
1610   * @see drupal_render_page()
1611   */
1612  function hook_page_alter(&$page) {
1613    // Add help text to the user login block.
1614    $page['sidebar_first']['user_login']['help'] = array(
1615      '#weight' => -10,
1616      '#markup' => t('To post comments or add new content, you first have to log in.'),
1617    );
1618  }
1619  
1620  /**
1621   * Perform alterations before a form is rendered.
1622   *
1623   * One popular use of this hook is to add form elements to the node form. When
1624   * altering a node form, the node object can be accessed at $form['#node'].
1625   *
1626   * In addition to hook_form_alter(), which is called for all forms, there are
1627   * two more specific form hooks available. The first,
1628   * hook_form_BASE_FORM_ID_alter(), allows targeting of a form/forms via a base
1629   * form (if one exists). The second, hook_form_FORM_ID_alter(), can be used to
1630   * target a specific form directly.
1631   *
1632   * The call order is as follows: all existing form alter functions are called
1633   * for module A, then all for module B, etc., followed by all for any base
1634   * theme(s), and finally for the theme itself. The module order is determined
1635   * by system weight, then by module name.
1636   *
1637   * Within each module, form alter hooks are called in the following order:
1638   * first, hook_form_alter(); second, hook_form_BASE_FORM_ID_alter(); third,
1639   * hook_form_FORM_ID_alter(). So, for each module, the more general hooks are
1640   * called first followed by the more specific.
1641   *
1642   * @param $form
1643   *   Nested array of form elements that comprise the form.
1644   * @param $form_state
1645   *   A keyed array containing the current state of the form. The arguments
1646   *   that drupal_get_form() was originally called with are available in the
1647   *   array $form_state['build_info']['args'].
1648   * @param $form_id
1649   *   String representing the name of the form itself. Typically this is the
1650   *   name of the function that generated the form.
1651   *
1652   * @see hook_form_BASE_FORM_ID_alter()
1653   * @see hook_form_FORM_ID_alter()
1654   * @see forms_api_reference.html
1655   */
1656  function hook_form_alter(&$form, &$form_state, $form_id) {
1657    if (isset($form['type']) && $form['type']['#value'] . '_node_settings' == $form_id) {
1658      $form['workflow']['upload_' . $form['type']['#value']] = array(
1659        '#type' => 'radios',
1660        '#title' => t('Attachments'),
1661        '#default_value' => variable_get('upload_' . $form['type']['#value'], 1),
1662        '#options' => array(t('Disabled'), t('Enabled')),
1663      );
1664    }
1665  }
1666  
1667  /**
1668   * Provide a form-specific alteration instead of the global hook_form_alter().
1669   *
1670   * Modules can implement hook_form_FORM_ID_alter() to modify a specific form,
1671   * rather than implementing hook_form_alter() and checking the form ID, or
1672   * using long switch statements to alter multiple forms.
1673   *
1674   * Form alter hooks are called in the following order: hook_form_alter(),
1675   * hook_form_BASE_FORM_ID_alter(), hook_form_FORM_ID_alter(). See
1676   * hook_form_alter() for more details.
1677   *
1678   * @param $form
1679   *   Nested array of form elements that comprise the form.
1680   * @param $form_state
1681   *   A keyed array containing the current state of the form. The arguments
1682   *   that drupal_get_form() was originally called with are available in the
1683   *   array $form_state['build_info']['args'].
1684   * @param $form_id
1685   *   String representing the name of the form itself. Typically this is the
1686   *   name of the function that generated the form.
1687   *
1688   * @see hook_form_alter()
1689   * @see hook_form_BASE_FORM_ID_alter()
1690   * @see drupal_prepare_form()
1691   * @see forms_api_reference.html
1692   */
1693  function hook_form_FORM_ID_alter(&$form, &$form_state, $form_id) {
1694    // Modification for the form with the given form ID goes here. For example, if
1695    // FORM_ID is "user_register_form" this code would run only on the user
1696    // registration form.
1697  
1698    // Add a checkbox to registration form about agreeing to terms of use.
1699    $form['terms_of_use'] = array(
1700      '#type' => 'checkbox',
1701      '#title' => t("I agree with the website's terms and conditions."),
1702      '#required' => TRUE,
1703    );
1704  }
1705  
1706  /**
1707   * Provide a form-specific alteration for shared ('base') forms.
1708   *
1709   * By default, when drupal_get_form() is called, Drupal looks for a function
1710   * with the same name as the form ID, and uses that function to build the form.
1711   * In contrast, base forms allow multiple form IDs to be mapped to a single base
1712   * (also called 'factory') form function.
1713   *
1714   * Modules can implement hook_form_BASE_FORM_ID_alter() to modify a specific
1715   * base form, rather than implementing hook_form_alter() and checking for
1716   * conditions that would identify the shared form constructor.
1717   *
1718   * To identify the base form ID for a particular form (or to determine whether
1719   * one exists) check the $form_state. The base form ID is stored under
1720   * $form_state['build_info']['base_form_id'].
1721   *
1722   * See hook_forms() for more information on how to implement base forms in
1723   * Drupal.
1724   *
1725   * Form alter hooks are called in the following order: hook_form_alter(),
1726   * hook_form_BASE_FORM_ID_alter(), hook_form_FORM_ID_alter(). See
1727   * hook_form_alter() for more details.
1728   *
1729   * @param $form
1730   *   Nested array of form elements that comprise the form.
1731   * @param $form_state
1732   *   A keyed array containing the current state of the form.
1733   * @param $form_id
1734   *   String representing the name of the form itself. Typically this is the
1735   *   name of the function that generated the form.
1736   *
1737   * @see hook_form_alter()
1738   * @see hook_form_FORM_ID_alter()
1739   * @see drupal_prepare_form()
1740   * @see hook_forms()
1741   */
1742  function hook_form_BASE_FORM_ID_alter(&$form, &$form_state, $form_id) {
1743    // Modification for the form with the given BASE_FORM_ID goes here. For
1744    // example, if BASE_FORM_ID is "node_form", this code would run on every
1745    // node form, regardless of node type.
1746  
1747    // Add a checkbox to the node form about agreeing to terms of use.
1748    $form['terms_of_use'] = array(
1749      '#type' => 'checkbox',
1750      '#title' => t("I agree with the website's terms and conditions."),
1751      '#required' => TRUE,
1752    );
1753  }
1754  
1755  /**
1756   * Map form_ids to form builder functions.
1757   *
1758   * By default, when drupal_get_form() is called, the system will look for a
1759   * function with the same name as the form ID, and use that function to build
1760   * the form. If no such function is found, Drupal calls this hook. Modules
1761   * implementing this hook can then provide their own instructions for mapping
1762   * form IDs to constructor functions. As a result, you can easily map multiple
1763   * form IDs to a single form constructor (referred to as a 'base' form).
1764   *
1765   * Using a base form can help to avoid code duplication, by allowing many
1766   * similar forms to use the same code base. Another benefit is that it becomes
1767   * much easier for other modules to apply a general change to the group of
1768   * forms; hook_form_BASE_FORM_ID_alter() can be used to easily alter multiple
1769   * forms at once by directly targeting the shared base form.
1770   *
1771   * Two example use cases where base forms may be useful are given below.
1772   *
1773   * First, you can use this hook to tell the form system to use a different
1774   * function to build certain forms in your module; this is often used to define
1775   * a form "factory" function that is used to build several similar forms. In
1776   * this case, your hook implementation will likely ignore all of the input
1777   * arguments. See node_forms() for an example of this. Note, node_forms() is the
1778   * hook_forms() implementation; the base form itself is defined in node_form().
1779   *
1780   * Second, you could use this hook to define how to build a form with a
1781   * dynamically-generated form ID. In this case, you would need to verify that
1782   * the $form_id input matched your module's format for dynamically-generated
1783   * form IDs, and if so, act appropriately.
1784   *
1785   * @param $form_id
1786   *   The unique string identifying the desired form.
1787   * @param $args
1788   *   An array containing the original arguments provided to drupal_get_form()
1789   *   or drupal_form_submit(). These are always passed to the form builder and
1790   *   do not have to be specified manually in 'callback arguments'.
1791   *
1792   * @return
1793   *   An associative array whose keys define form_ids and whose values are an
1794   *   associative array defining the following keys:
1795   *   - callback: The name of the form builder function to invoke. This will be
1796   *     used for the base form ID, for example, to target a base form using
1797   *     hook_form_BASE_FORM_ID_alter().
1798   *   - callback arguments: (optional) Additional arguments to pass to the
1799   *     function defined in 'callback', which are prepended to $args.
1800   *   - wrapper_callback: (optional) The name of a form builder function to
1801   *     invoke before the form builder defined in 'callback' is invoked. This
1802   *     wrapper callback may prepopulate the $form array with form elements,
1803   *     which will then be already contained in the $form that is passed on to
1804   *     the form builder defined in 'callback'. For example, a wrapper callback
1805   *     could setup wizard-alike form buttons that are the same for a variety of
1806   *     forms that belong to the wizard, which all share the same wrapper
1807   *     callback.
1808   */
1809  function hook_forms($form_id, $args) {
1810    // Simply reroute the (non-existing) $form_id 'mymodule_first_form' to
1811    // 'mymodule_main_form'.
1812    $forms['mymodule_first_form'] = array(
1813      'callback' => 'mymodule_main_form',
1814    );
1815  
1816    // Reroute the $form_id and prepend an additional argument that gets passed to
1817    // the 'mymodule_main_form' form builder function.
1818    $forms['mymodule_second_form'] = array(
1819      'callback' => 'mymodule_main_form',
1820      'callback arguments' => array('some parameter'),
1821    );
1822  
1823    // Reroute the $form_id, but invoke the form builder function
1824    // 'mymodule_main_form_wrapper' first, so we can prepopulate the $form array
1825    // that is passed to the actual form builder 'mymodule_main_form'.
1826    $forms['mymodule_wrapped_form'] = array(
1827      'callback' => 'mymodule_main_form',
1828      'wrapper_callback' => 'mymodule_main_form_wrapper',
1829    );
1830  
1831    return $forms;
1832  }
1833  
1834  /**
1835   * Perform setup tasks for all page requests.
1836   *
1837   * This hook is run at the beginning of the page request. It is typically
1838   * used to set up global parameters that are needed later in the request.
1839   *
1840   * Only use this hook if your code must run even for cached page views. This
1841   * hook is called before the theme, modules, or most include files are loaded
1842   * into memory. It happens while Drupal is still in bootstrap mode.
1843   *
1844   * @see hook_init()
1845   */
1846  function hook_boot() {
1847    // We need user_access() in the shutdown function. Make sure it gets loaded.
1848    drupal_load('module', 'user');
1849    drupal_register_shutdown_function('devel_shutdown');
1850  }
1851  
1852  /**
1853   * Perform setup tasks for non-cached page requests.
1854   *
1855   * This hook is run at the beginning of the page request. It is typically
1856   * used to set up global parameters that are needed later in the request.
1857   * When this hook is called, the theme and all modules are already loaded in
1858   * memory.
1859   *
1860   * This hook is not run on cached pages.
1861   *
1862   * To add CSS or JS that should be present on all pages, modules should not
1863   * implement this hook, but declare these files in their .info file.
1864   *
1865   * @see hook_boot()
1866   */
1867  function hook_init() {
1868    // Since this file should only be loaded on the front page, it cannot be
1869    // declared in the info file.
1870    if (drupal_is_front_page()) {
1871      drupal_add_css(drupal_get_path('module', 'foo') . '/foo.css');
1872    }
1873  }
1874  
1875  /**
1876   * Define image toolkits provided by this module.
1877   *
1878   * The file which includes each toolkit's functions must be declared as part of
1879   * the files array in the module .info file so that the registry will find and
1880   * parse it.
1881   *
1882   * The toolkit's functions must be named image_toolkitname_operation().
1883   * where the operation may be:
1884   *   - 'load': Required. See image_gd_load() for usage.
1885   *   - 'save': Required. See image_gd_save() for usage.
1886   *   - 'settings': Optional. See image_gd_settings() for usage.
1887   *   - 'resize': Optional. See image_gd_resize() for usage.
1888   *   - 'rotate': Optional. See image_gd_rotate() for usage.
1889   *   - 'crop': Optional. See image_gd_crop() for usage.
1890   *   - 'desaturate': Optional. See image_gd_desaturate() for usage.
1891   *
1892   * @return
1893   *   An array with the toolkit name as keys and sub-arrays with these keys:
1894   *     - 'title': A string with the toolkit's title.
1895   *     - 'available': A Boolean value to indicate that the toolkit is operating
1896   *       properly, e.g. all required libraries exist.
1897   *
1898   * @see system_image_toolkits()
1899   */
1900  function hook_image_toolkits() {
1901    return array(
1902      'working' => array(
1903        'title' => t('A toolkit that works.'),
1904        'available' => TRUE,
1905      ),
1906      'broken' => array(
1907        'title' => t('A toolkit that is "broken" and will not be listed.'),
1908        'available' => FALSE,
1909      ),
1910    );
1911  }
1912  
1913  /**
1914   * Alter an email message created with the drupal_mail() function.
1915   *
1916   * hook_mail_alter() allows modification of email messages created and sent
1917   * with drupal_mail(). Usage examples include adding and/or changing message
1918   * text, message fields, and message headers.
1919   *
1920   * Email messages sent using functions other than drupal_mail() will not
1921   * invoke hook_mail_alter(). For example, a contributed module directly
1922   * calling the drupal_mail_system()->mail() or PHP mail() function
1923   * will not invoke this hook. All core modules use drupal_mail() for
1924   * messaging, it is best practice but not mandatory in contributed modules.
1925   *
1926   * @param $message
1927   *   An array containing the message data. Keys in this array include:
1928   *  - 'id':
1929   *     The drupal_mail() id of the message. Look at module source code or
1930   *     drupal_mail() for possible id values.
1931   *  - 'to':
1932   *     The address or addresses the message will be sent to. The
1933   *     formatting of this string must comply with RFC 2822.
1934   *  - 'from':
1935   *     The address the message will be marked as being from, which is
1936   *     either a custom address or the site-wide default email address.
1937   *  - 'subject':
1938   *     Subject of the email to be sent. This must not contain any newline
1939   *     characters, or the email may not be sent properly.
1940   *  - 'body':
1941   *     An array of strings containing the message text. The message body is
1942   *     created by concatenating the individual array strings into a single text
1943   *     string using "\n\n" as a separator.
1944   *  - 'headers':
1945   *     Associative array containing mail headers, such as From, Sender,
1946   *     MIME-Version, Content-Type, etc.
1947   *  - 'params':
1948   *     An array of optional parameters supplied by the caller of drupal_mail()
1949   *     that is used to build the message before hook_mail_alter() is invoked.
1950   *  - 'language':
1951   *     The language object used to build the message before hook_mail_alter()
1952   *     is invoked.
1953   *  - 'send':
1954   *     Set to FALSE to abort sending this email message.
1955   *
1956   * @see drupal_mail()
1957   */
1958  function hook_mail_alter(&$message) {
1959    if ($message['id'] == 'modulename_messagekey') {
1960      if (!example_notifications_optin($message['to'], $message['id'])) {
1961        // If the recipient has opted to not receive such messages, cancel
1962        // sending.
1963        $message['send'] = FALSE;
1964        return;
1965      }
1966      $message['body'][] = "--\nMail sent out from " . variable_get('site_name', t('Drupal'));
1967    }
1968  }
1969  
1970  /**
1971   * Alter the registry of modules implementing a hook.
1972   *
1973   * This hook is invoked during module_implements(). A module may implement this
1974   * hook in order to reorder the implementing modules, which are otherwise
1975   * ordered by the module's system weight.
1976   *
1977   * Note that hooks invoked using drupal_alter() can have multiple variations
1978   * (such as hook_form_alter() and hook_form_FORM_ID_alter()). drupal_alter()
1979   * will call all such variants defined by a single module in turn. For the
1980   * purposes of hook_module_implements_alter(), these variants are treated as
1981   * a single hook. Thus, to ensure that your implementation of
1982   * hook_form_FORM_ID_alter() is called at the right time, you will have to
1983   * change the order of hook_form_alter() implementation in
1984   * hook_module_implements_alter().
1985   *
1986   * @param $implementations
1987   *   An array keyed by the module's name. The value of each item corresponds
1988   *   to a $group, which is usually FALSE, unless the implementation is in a
1989   *   file named $module.$group.inc.
1990   * @param $hook
1991   *   The name of the module hook being implemented.
1992   */
1993  function hook_module_implements_alter(&$implementations, $hook) {
1994    if ($hook == 'rdf_mapping') {
1995      // Move my_module_rdf_mapping() to the end of the list. module_implements()
1996      // iterates through $implementations with a foreach loop which PHP iterates
1997      // in the order that the items were added, so to move an item to the end of
1998      // the array, we remove it and then add it.
1999      $group = $implementations['my_module'];
2000      unset($implementations['my_module']);
2001      $implementations['my_module'] = $group;
2002    }
2003  }
2004  
2005  /**
2006   * Return additional themes provided by modules.
2007   *
2008   * Only use this hook for testing purposes. Use a hidden MYMODULE_test.module
2009   * to implement this hook. Testing themes should be hidden, too.
2010   *
2011   * This hook is invoked from _system_rebuild_theme_data() and allows modules to
2012   * register additional themes outside of the regular 'themes' directories of a
2013   * Drupal installation.
2014   *
2015   * @return
2016   *   An associative array. Each key is the system name of a theme and each value
2017   *   is the corresponding path to the theme's .info file.
2018   */
2019  function hook_system_theme_info() {
2020    $themes['mymodule_test_theme'] = drupal_get_path('module', 'mymodule') . '/mymodule_test_theme/mymodule_test_theme.info';
2021    return $themes;
2022  }
2023  
2024  /**
2025   * Alter the information parsed from module and theme .info files
2026   *
2027   * This hook is invoked in _system_rebuild_module_data() and in
2028   * _system_rebuild_theme_data(). A module may implement this hook in order to
2029   * add to or alter the data generated by reading the .info file with
2030   * drupal_parse_info_file().
2031   *
2032   * @param $info
2033   *   The .info file contents, passed by reference so that it can be altered.
2034   * @param $file
2035   *   Full information about the module or theme, including $file->name, and
2036   *   $file->filename
2037   * @param $type
2038   *   Either 'module' or 'theme', depending on the type of .info file that was
2039   *   passed.
2040   */
2041  function hook_system_info_alter(&$info, $file, $type) {
2042    // Only fill this in if the .info file does not define a 'datestamp'.
2043    if (empty($info['datestamp'])) {
2044      $info['datestamp'] = filemtime($file->filename);
2045    }
2046  }
2047  
2048  /**
2049   * Define user permissions.
2050   *
2051   * This hook can supply permissions that the module defines, so that they
2052   * can be selected on the user permissions page and used to grant or restrict
2053   * access to actions the module performs.
2054   *
2055   * Permissions are checked using user_access().
2056   *
2057   * For a detailed usage example, see page_example.module.
2058   *
2059   * @return
2060   *   An array whose keys are permission names and whose corresponding values
2061   *   are arrays containing the following key-value pairs:
2062   *   - title: The human-readable name of the permission, to be shown on the
2063   *     permission administration page. This should be wrapped in the t()
2064   *     function so it can be translated.
2065   *   - description: (optional) A description of what the permission does. This
2066   *     should be wrapped in the t() function so it can be translated.
2067   *   - restrict access: (optional) A boolean which can be set to TRUE to
2068   *     indicate that site administrators should restrict access to this
2069   *     permission to trusted users. This should be used for permissions that
2070   *     have inherent security risks across a variety of potential use cases
2071   *     (for example, the "administer filters" and "bypass node access"
2072   *     permissions provided by Drupal core). When set to TRUE, a standard
2073   *     warning message defined in user_admin_permissions() and output via
2074   *     theme_user_permission_description() will be associated with the
2075   *     permission and displayed with it on the permission administration page.
2076   *     Defaults to FALSE.
2077   *   - warning: (optional) A translated warning message to display for this
2078   *     permission on the permission administration page. This warning overrides
2079   *     the automatic warning generated by 'restrict access' being set to TRUE.
2080   *     This should rarely be used, since it is important for all permissions to
2081   *     have a clear, consistent security warning that is the same across the
2082   *     site. Use the 'description' key instead to provide any information that
2083   *     is specific to the permission you are defining.
2084   *
2085   * @see theme_user_permission_description()
2086   */
2087  function hook_permission() {
2088    return array(
2089      'administer my module' =>  array(
2090        'title' => t('Administer my module'),
2091        'description' => t('Perform administration tasks for my module.'),
2092      ),
2093    );
2094  }
2095  
2096  /**
2097   * Register a module (or theme's) theme implementations.
2098   *
2099   * The implementations declared by this hook have two purposes: either they
2100   * specify how a particular render array is to be rendered as HTML (this is
2101   * usually the case if the theme function is assigned to the render array's
2102   * #theme property), or they return the HTML that should be returned by an
2103   * invocation of theme().
2104   *
2105   * The following parameters are all optional.
2106   *
2107   * @param array $existing
2108   *   An array of existing implementations that may be used for override
2109   *   purposes. This is primarily useful for themes that may wish to examine
2110   *   existing implementations to extract data (such as arguments) so that
2111   *   it may properly register its own, higher priority implementations.
2112   * @param $type
2113   *   Whether a theme, module, etc. is being processed. This is primarily useful
2114   *   so that themes tell if they are the actual theme being called or a parent
2115   *   theme. May be one of:
2116   *   - 'module': A module is being checked for theme implementations.
2117   *   - 'base_theme_engine': A theme engine is being checked for a theme that is
2118   *     a parent of the actual theme being used.
2119   *   - 'theme_engine': A theme engine is being checked for the actual theme
2120   *     being used.
2121   *   - 'base_theme': A base theme is being checked for theme implementations.
2122   *   - 'theme': The actual theme in use is being checked.
2123   * @param $theme
2124   *   The actual name of theme, module, etc. that is being being processed.
2125   * @param $path
2126   *   The directory path of the theme or module, so that it doesn't need to be
2127   *   looked up.
2128   *
2129   * @return array
2130   *   An associative array of theme hook information. The keys on the outer
2131   *   array are the internal names of the hooks, and the values are arrays
2132   *   containing information about the hook. Each information array must contain
2133   *   either a 'variables' element or a 'render element' element, but not both.
2134   *   Use 'render element' if you are theming a single element or element tree
2135   *   composed of elements, such as a form array, a page array, or a single
2136   *   checkbox element. Use 'variables' if your theme implementation is
2137   *   intended to be called directly through theme() and has multiple arguments
2138   *   for the data and style; in this case, the variables not supplied by the
2139   *   calling function will be given default values and passed to the template
2140   *   or theme function. The returned theme information array can contain the
2141   *   following key/value pairs:
2142   *   - variables: (see above) Each array key is the name of the variable, and
2143   *     the value given is used as the default value if the function calling
2144   *     theme() does not supply it. Template implementations receive each array
2145   *     key as a variable in the template file (so they must be legal PHP
2146   *     variable names). Function implementations are passed the variables in a
2147   *     single $variables function argument.
2148   *   - render element: (see above) The name of the renderable element or element
2149   *     tree to pass to the theme function. This name is used as the name of the
2150   *     variable that holds the renderable element or tree in preprocess and
2151   *     process functions.
2152   *   - file: The file the implementation resides in. This file will be included
2153   *     prior to the theme being rendered, to make sure that the function or
2154   *     preprocess function (as needed) is actually loaded; this makes it
2155   *     possible to split theme functions out into separate files quite easily.
2156   *   - path: Override the path of the file to be used. Ordinarily the module or
2157   *     theme path will be used, but if the file will not be in the default
2158   *     path, include it here. This path should be relative to the Drupal root
2159   *     directory.
2160   *   - template: If specified, this theme implementation is a template, and
2161   *     this is the template file without an extension. Do not put .tpl.php on
2162   *     this file; that extension will be added automatically by the default
2163   *     rendering engine (which is PHPTemplate). If 'path', above, is specified,
2164   *     the template should also be in this path.
2165   *   - function: If specified, this will be the function name to invoke for
2166   *     this implementation. If neither 'template' nor 'function' is specified,
2167   *     a default function name will be assumed. For example, if a module
2168   *     registers the 'node' theme hook, 'theme_node' will be assigned to its
2169   *     function. If the chameleon theme registers the node hook, it will be
2170   *     assigned 'chameleon_node' as its function.
2171   *   - base hook: A string declaring the base theme hook if this theme
2172   *     implementation is actually implementing a suggestion for another theme
2173   *     hook.
2174   *   - pattern: A regular expression pattern to be used to allow this theme
2175   *     implementation to have a dynamic name. The convention is to use __ to
2176   *     differentiate the dynamic portion of the theme. For example, to allow
2177   *     forums to be themed individually, the pattern might be: 'forum__'. Then,
2178   *     when the forum is themed, call:
2179   *     @code
2180   *     theme(array('forum__' . $tid, 'forum'), $forum)
2181   *     @endcode
2182   *   - preprocess functions: A list of functions used to preprocess this data.
2183   *     Ordinarily this won't be used; it's automatically filled in. By default,
2184   *     for a module this will be filled in as template_preprocess_HOOK. For
2185   *     a theme this will be filled in as phptemplate_preprocess and
2186   *     phptemplate_preprocess_HOOK as well as themename_preprocess and
2187   *     themename_preprocess_HOOK.
2188   *   - override preprocess functions: Set to TRUE when a theme does NOT want
2189   *     the standard preprocess functions to run. This can be used to give a
2190   *     theme FULL control over how variables are set. For example, if a theme
2191   *     wants total control over how certain variables in the page.tpl.php are
2192   *     set, this can be set to true. Please keep in mind that when this is used
2193   *     by a theme, that theme becomes responsible for making sure necessary
2194   *     variables are set.
2195   *   - type: (automatically derived) Where the theme hook is defined:
2196   *     'module', 'theme_engine', or 'theme'.
2197   *   - theme path: (automatically derived) The directory path of the theme or
2198   *     module, so that it doesn't need to be looked up.
2199   */
2200  function hook_theme($existing, $type, $theme, $path) {
2201    return array(
2202      'forum_display' => array(
2203        'variables' => array('forums' => NULL, 'topics' => NULL, 'parents' => NULL, 'tid' => NULL, 'sortby' => NULL, 'forum_per_page' => NULL),
2204      ),
2205      'forum_list' => array(
2206        'variables' => array('forums' => NULL, 'parents' => NULL, 'tid' => NULL),
2207      ),
2208      'forum_topic_list' => array(
2209        'variables' => array('tid' => NULL, 'topics' => NULL, 'sortby' => NULL, 'forum_per_page' => NULL),
2210      ),
2211      'forum_icon' => array(
2212        'variables' => array('new_posts' => NULL, 'num_posts' => 0, 'comment_mode' => 0, 'sticky' => 0),
2213      ),
2214      'status_report' => array(
2215        'render element' => 'requirements',
2216        'file' => 'system.admin.inc',
2217      ),
2218      'system_date_time_settings' => array(
2219        'render element' => 'form',
2220        'file' => 'system.admin.inc',
2221      ),
2222    );
2223  }
2224  
2225  /**
2226   * Alter the theme registry information returned from hook_theme().
2227   *
2228   * The theme registry stores information about all available theme hooks,
2229   * including which callback functions those hooks will call when triggered,
2230   * what template files are exposed by these hooks, and so on.
2231   *
2232   * Note that this hook is only executed as the theme cache is re-built.
2233   * Changes here will not be visible until the next cache clear.
2234   *
2235   * The $theme_registry array is keyed by theme hook name, and contains the
2236   * information returned from hook_theme(), as well as additional properties
2237   * added by _theme_process_registry().
2238   *
2239   * For example:
2240   * @code
2241   * $theme_registry['user_profile'] = array(
2242   *   'variables' => array(
2243   *     'account' => NULL,
2244   *   ),
2245   *   'template' => 'modules/user/user-profile',
2246   *   'file' => 'modules/user/user.pages.inc',
2247   *   'type' => 'module',
2248   *   'theme path' => 'modules/user',
2249   *   'preprocess functions' => array(
2250   *     0 => 'template_preprocess',
2251   *     1 => 'template_preprocess_user_profile',
2252   *   ),
2253   * );
2254   * @endcode
2255   *
2256   * @param $theme_registry
2257   *   The entire cache of theme registry information, post-processing.
2258   *
2259   * @see hook_theme()
2260   * @see _theme_process_registry()
2261   */
2262  function hook_theme_registry_alter(&$theme_registry) {
2263    // Kill the next/previous forum topic navigation links.
2264    foreach ($theme_registry['forum_topic_navigation']['preprocess functions'] as $key => $value) {
2265      if ($value == 'template_preprocess_forum_topic_navigation') {
2266        unset($theme_registry['forum_topic_navigation']['preprocess functions'][$key]);
2267      }
2268    }
2269  }
2270  
2271  /**
2272   * Return the machine-readable name of the theme to use for the current page.
2273   *
2274   * This hook can be used to dynamically set the theme for the current page
2275   * request. It should be used by modules which need to override the theme
2276   * based on dynamic conditions (for example, a module which allows the theme to
2277   * be set based on the current user's role). The return value of this hook will
2278   * be used on all pages except those which have a valid per-page or per-section
2279   * theme set via a theme callback function in hook_menu(); the themes on those
2280   * pages can only be overridden using hook_menu_alter().
2281   *
2282   * Note that returning different themes for the same path may not work with page
2283   * caching. This is most likely to be a problem if an anonymous user on a given
2284   * path could have different themes returned under different conditions.
2285   *
2286   * Since only one theme can be used at a time, the last (i.e., highest
2287   * weighted) module which returns a valid theme name from this hook will
2288   * prevail.
2289   *
2290   * @return
2291   *   The machine-readable name of the theme that should be used for the current
2292   *   page request. The value returned from this function will only have an
2293   *   effect if it corresponds to a currently-active theme on the site.
2294   */
2295  function hook_custom_theme() {
2296    // Allow the user to request a particular theme via a query parameter.
2297    if (isset($_GET['theme'])) {
2298      return $_GET['theme'];
2299    }
2300  }
2301  
2302  /**
2303   * Register XML-RPC callbacks.
2304   *
2305   * This hook lets a module register callback functions to be called when
2306   * particular XML-RPC methods are invoked by a client.
2307   *
2308   * @return
2309   *   An array which maps XML-RPC methods to Drupal functions. Each array
2310   *   element is either a pair of method => function or an array with four
2311   *   entries:
2312   *   - The XML-RPC method name (for example, module.function).
2313   *   - The Drupal callback function (for example, module_function).
2314   *   - The method signature is an array of XML-RPC types. The first element
2315   *     of this array is the type of return value and then you should write a
2316   *     list of the types of the parameters. XML-RPC types are the following
2317   *     (See the types at http://www.xmlrpc.com/spec):
2318   *       - "boolean": 0 (false) or 1 (true).
2319   *       - "double": a floating point number (for example, -12.214).
2320   *       - "int": a integer number (for example,  -12).
2321   *       - "array": an array without keys (for example, array(1, 2, 3)).
2322   *       - "struct": an associative array or an object (for example,
2323   *          array('one' => 1, 'two' => 2)).
2324   *       - "date": when you return a date, then you may either return a
2325   *          timestamp (time(), mktime() etc.) or an ISO8601 timestamp. When
2326   *          date is specified as an input parameter, then you get an object,
2327   *          which is described in the function xmlrpc_date
2328   *       - "base64": a string containing binary data, automatically
2329   *          encoded/decoded automatically.
2330   *       - "string": anything else, typically a string.
2331   *   - A descriptive help string, enclosed in a t() function for translation
2332   *     purposes.
2333   *   Both forms are shown in the example.
2334   */
2335  function hook_xmlrpc() {
2336    return array(
2337      'drupal.login' => 'drupal_login',
2338      array(
2339        'drupal.site.ping',
2340        'drupal_directory_ping',
2341        array('boolean', 'string', 'string', 'string', 'string', 'string'),
2342        t('Handling ping request'))
2343    );
2344  }
2345  
2346  /**
2347   * Alters the definition of XML-RPC methods before they are called.
2348   *
2349   * This hook allows modules to modify the callback definition of declared
2350   * XML-RPC methods, right before they are invoked by a client. Methods may be
2351   * added, or existing methods may be altered.
2352   *
2353   * Note that hook_xmlrpc() supports two distinct and incompatible formats to
2354   * define a callback, so care must be taken when altering other methods.
2355   *
2356   * @param $methods
2357   *   An asssociative array of method callback definitions, as returned from
2358   *   hook_xmlrpc() implementations.
2359   *
2360   * @see hook_xmlrpc()
2361   * @see xmlrpc_server()
2362   */
2363  function hook_xmlrpc_alter(&$methods) {
2364    // Directly change a simple method.
2365    $methods['drupal.login'] = 'mymodule_login';
2366  
2367    // Alter complex definitions.
2368    foreach ($methods as $key => &$method) {
2369      // Skip simple method definitions.
2370      if (!is_int($key)) {
2371        continue;
2372      }
2373      // Perform the wanted manipulation.
2374      if ($method[0] == 'drupal.site.ping') {
2375        $method[1] = 'mymodule_directory_ping';
2376      }
2377    }
2378  }
2379  
2380  /**
2381   * Log an event message.
2382   *
2383   * This hook allows modules to route log events to custom destinations, such as
2384   * SMS, Email, pager, syslog, ...etc.
2385   *
2386   * @param $log_entry
2387   *   An associative array containing the following keys:
2388   *   - type: The type of message for this entry.
2389   *   - user: The user object for the user who was logged in when the event
2390   *     happened.
2391   *   - uid: The user ID for the user who was logged in when the event happened.
2392   *   - request_uri: The request URI for the page the event happened in.
2393   *   - referer: The page that referred the user to the page where the event
2394   *     occurred.
2395   *   - ip: The IP address where the request for the page came from.
2396   *   - timestamp: The UNIX timestamp of the date/time the event occurred.
2397   *   - severity: The severity of the message; one of the following values as
2398   *     defined in @link http://www.faqs.org/rfcs/rfc3164.html RFC 3164: @endlink
2399   *     - WATCHDOG_EMERGENCY: Emergency, system is unusable.
2400   *     - WATCHDOG_ALERT: Alert, action must be taken immediately.
2401   *     - WATCHDOG_CRITICAL: Critical conditions.
2402   *     - WATCHDOG_ERROR: Error conditions.
2403   *     - WATCHDOG_WARNING: Warning conditions.
2404   *     - WATCHDOG_NOTICE: Normal but significant conditions.
2405   *     - WATCHDOG_INFO: Informational messages.
2406   *     - WATCHDOG_DEBUG: Debug-level messages.
2407   *   - link: An optional link provided by the module that called the watchdog()
2408   *     function.
2409   *   - message: The text of the message to be logged. Variables in the message
2410   *     are indicated by using placeholder strings alongside the variables
2411   *     argument to declare the value of the placeholders. See t() for
2412   *     documentation on how the message and variable parameters interact.
2413   *   - variables: An array of variables to be inserted into the message on
2414   *     display. Will be NULL or missing if a message is already translated or if
2415   *     the message is not possible to translate.
2416   */
2417  function hook_watchdog(array $log_entry) {
2418    global $base_url, $language;
2419  
2420    $severity_list = array(
2421      WATCHDOG_EMERGENCY => t('Emergency'),
2422      WATCHDOG_ALERT     => t('Alert'),
2423      WATCHDOG_CRITICAL  => t('Critical'),
2424      WATCHDOG_ERROR     => t('Error'),
2425      WATCHDOG_WARNING   => t('Warning'),
2426      WATCHDOG_NOTICE    => t('Notice'),
2427      WATCHDOG_INFO      => t('Info'),
2428      WATCHDOG_DEBUG     => t('Debug'),
2429    );
2430  
2431    $to = 'someone@example.com';
2432    $params = array();
2433    $params['subject'] = t('[@site_name] @severity_desc: Alert from your web site', array(
2434      '@site_name' => variable_get('site_name', 'Drupal'),
2435      '@severity_desc' => $severity_list[$log_entry['severity']],
2436    ));
2437  
2438    $params['message']  = "\nSite:         @base_url";
2439    $params['message'] .= "\nSeverity:     (@severity) @severity_desc";
2440    $params['message'] .= "\nTimestamp:    @timestamp";
2441    $params['message'] .= "\nType:         @type";
2442    $params['message'] .= "\nIP Address:   @ip";
2443    $params['message'] .= "\nRequest URI:  @request_uri";
2444    $params['message'] .= "\nReferrer URI: @referer_uri";
2445    $params['message'] .= "\nUser:         (@uid) @name";
2446    $params['message'] .= "\nLink:         @link";
2447    $params['message'] .= "\nMessage:      \n\n@message";
2448  
2449    $params['message'] = t($params['message'], array(
2450      '@base_url'      => $base_url,
2451      '@severity'      => $log_entry['severity'],
2452      '@severity_desc' => $severity_list[$log_entry['severity']],
2453      '@timestamp'     => format_date($log_entry['timestamp']),
2454      '@type'          => $log_entry['type'],
2455      '@ip'            => $log_entry['ip'],
2456      '@request_uri'   => $log_entry['request_uri'],
2457      '@referer_uri'   => $log_entry['referer'],
2458      '@uid'           => $log_entry['uid'],
2459      '@name'          => $log_entry['user']->name,
2460      '@link'          => strip_tags($log_entry['link']),
2461      '@message'       => strip_tags($log_entry['message']),
2462    ));
2463  
2464    drupal_mail('emaillog', 'entry', $to, $language, $params);
2465  }
2466  
2467  /**
2468   * Prepare a message based on parameters; called from drupal_mail().
2469   *
2470   * Note that hook_mail(), unlike hook_mail_alter(), is only called on the
2471   * $module argument to drupal_mail(), not all modules.
2472   *
2473   * @param $key
2474   *   An identifier of the mail.
2475   * @param $message
2476   *   An array to be filled in. Elements in this array include:
2477   *   - id: An ID to identify the mail sent. Look at module source code
2478   *     or drupal_mail() for possible id values.
2479   *   - to: The address or addresses the message will be sent to. The
2480   *     formatting of this string must comply with RFC 2822.
2481   *   - subject: Subject of the e-mail to be sent. This must not contain any
2482   *     newline characters, or the mail may not be sent properly. drupal_mail()
2483   *     sets this to an empty string when the hook is invoked.
2484   *   - body: An array of lines containing the message to be sent. Drupal will
2485   *     format the correct line endings for you. drupal_mail() sets this to an
2486   *     empty array when the hook is invoked.
2487   *   - from: The address the message will be marked as being from, which is
2488   *     set by drupal_mail() to either a custom address or the site-wide
2489   *     default email address when the hook is invoked.
2490   *   - headers: Associative array containing mail headers, such as From,
2491   *     Sender, MIME-Version, Content-Type, etc. drupal_mail() pre-fills
2492   *     several headers in this array.
2493   * @param $params
2494   *   An array of parameters supplied by the caller of drupal_mail().
2495   */
2496  function hook_mail($key, &$message, $params) {
2497    $account = $params['account'];
2498    $context = $params['context'];
2499    $variables = array(
2500      '%site_name' => variable_get('site_name', 'Drupal'),
2501      '%username' => format_username($account),
2502    );
2503    if ($context['hook'] == 'taxonomy') {
2504      $entity = $params['entity'];
2505      $vocabulary = taxonomy_vocabulary_load($entity->vid);
2506      $variables += array(
2507        '%term_name' => $entity->name,
2508        '%term_description' => $entity->description,
2509        '%term_id' => $entity->tid,
2510        '%vocabulary_name' => $vocabulary->name,
2511        '%vocabulary_description' => $vocabulary->description,
2512        '%vocabulary_id' => $vocabulary->vid,
2513      );
2514    }
2515  
2516    // Node-based variable translation is only available if we have a node.
2517    if (isset($params['node'])) {
2518      $node = $params['node'];
2519      $variables += array(
2520        '%uid' => $node->uid,
2521        '%node_url' => url('node/' . $node->nid, array('absolute' => TRUE)),
2522        '%node_type' => node_type_get_name($node),
2523        '%title' => $node->title,
2524        '%teaser' => $node->teaser,
2525        '%body' => $node->body,
2526      );
2527    }
2528    $subject = strtr($context['subject'], $variables);
2529    $body = strtr($context['message'], $variables);
2530    $message['subject'] .= str_replace(array("\r", "\n"), '', $subject);
2531    $message['body'][] = drupal_html_to_text($body);
2532  }
2533  
2534  /**
2535   * Add a list of cache tables to be cleared.
2536   *
2537   * This hook allows your module to add cache table names to the list of cache
2538   * tables that will be cleared by the Clear button on the Performance page or
2539   * whenever drupal_flush_all_caches is invoked.
2540   *
2541   * @return
2542   *   An array of cache table names.
2543   *
2544   * @see drupal_flush_all_caches()
2545   */
2546  function hook_flush_caches() {
2547    return array('cache_example');
2548  }
2549  
2550  /**
2551   * Perform necessary actions after modules are installed.
2552   *
2553   * This function differs from hook_install() in that it gives all other modules
2554   * a chance to perform actions when a module is installed, whereas
2555   * hook_install() is only called on the module actually being installed. See
2556   * module_enable() for a detailed description of the order in which install and
2557   * enable hooks are invoked.
2558   *
2559   * @param $modules
2560   *   An array of the modules that were installed.
2561   *
2562   * @see module_enable()
2563   * @see hook_modules_enabled()
2564   * @see hook_install()
2565   */
2566  function hook_modules_installed($modules) {
2567    if (in_array('lousy_module', $modules)) {
2568      variable_set('lousy_module_conflicting_variable', FALSE);
2569    }
2570  }
2571  
2572  /**
2573   * Perform necessary actions after modules are enabled.
2574   *
2575   * This function differs from hook_enable() in that it gives all other modules a
2576   * chance to perform actions when modules are enabled, whereas hook_enable() is
2577   * only called on the module actually being enabled. See module_enable() for a
2578   * detailed description of the order in which install and enable hooks are
2579   * invoked.
2580   *
2581   * @param $modules
2582   *   An array of the modules that were enabled.
2583   *
2584   * @see hook_enable()
2585   * @see hook_modules_installed()
2586   * @see module_enable()
2587   */
2588  function hook_modules_enabled($modules) {
2589    if (in_array('lousy_module', $modules)) {
2590      drupal_set_message(t('mymodule is not compatible with lousy_module'), 'error');
2591      mymodule_disable_functionality();
2592    }
2593  }
2594  
2595  /**
2596   * Perform necessary actions after modules are disabled.
2597   *
2598   * This function differs from hook_disable() in that it gives all other modules
2599   * a chance to perform actions when modules are disabled, whereas hook_disable()
2600   * is only called on the module actually being disabled.
2601   *
2602   * @param $modules
2603   *   An array of the modules that were disabled.
2604   *
2605   * @see hook_disable()
2606   * @see hook_modules_uninstalled()
2607   */
2608  function hook_modules_disabled($modules) {
2609    if (in_array('lousy_module', $modules)) {
2610      mymodule_enable_functionality();
2611    }
2612  }
2613  
2614  /**
2615   * Perform necessary actions after modules are uninstalled.
2616   *
2617   * This function differs from hook_uninstall() in that it gives all other
2618   * modules a chance to perform actions when a module is uninstalled, whereas
2619   * hook_uninstall() is only called on the module actually being uninstalled.
2620   *
2621   * It is recommended that you implement this hook if your module stores
2622   * data that may have been set by other modules.
2623   *
2624   * @param $modules
2625   *   An array of the modules that were uninstalled.
2626   *
2627   * @see hook_uninstall()
2628   * @see hook_modules_disabled()
2629   */
2630  function hook_modules_uninstalled($modules) {
2631    foreach ($modules as $module) {
2632      db_delete('mymodule_table')
2633        ->condition('module', $module)
2634        ->execute();
2635    }
2636    mymodule_cache_rebuild();
2637  }
2638  
2639  /**
2640   * Registers PHP stream wrapper implementations associated with a module.
2641   *
2642   * Provide a facility for managing and querying user-defined stream wrappers
2643   * in PHP. PHP's internal stream_get_wrappers() doesn't return the class
2644   * registered to handle a stream, which we need to be able to find the handler
2645   * for class instantiation.
2646   *
2647   * If a module registers a scheme that is already registered with PHP, it will
2648   * be unregistered and replaced with the specified class.
2649   *
2650   * @return
2651   *   A nested array, keyed first by scheme name ("public" for "public://"),
2652   *   then keyed by the following values:
2653   *   - 'name' A short string to name the wrapper.
2654   *   - 'class' A string specifying the PHP class that implements the
2655   *     DrupalStreamWrapperInterface interface.
2656   *   - 'description' A string with a short description of what the wrapper does.
2657   *   - 'type' (Optional) A bitmask of flags indicating what type of streams this
2658   *     wrapper will access - local or remote, readable and/or writeable, etc.
2659   *     Many shortcut constants are defined in stream_wrappers.inc. Defaults to
2660   *     STREAM_WRAPPERS_NORMAL which includes all of these bit flags:
2661   *     - STREAM_WRAPPERS_READ
2662   *     - STREAM_WRAPPERS_WRITE
2663   *     - STREAM_WRAPPERS_VISIBLE
2664   *
2665   * @see file_get_stream_wrappers()
2666   * @see hook_stream_wrappers_alter()
2667   * @see system_stream_wrappers()
2668   */
2669  function hook_stream_wrappers() {
2670    return array(
2671      'public' => array(
2672        'name' => t('Public files'),
2673        'class' => 'DrupalPublicStreamWrapper',
2674        'description' => t('Public local files served by the webserver.'),
2675        'type' => STREAM_WRAPPERS_LOCAL_NORMAL,
2676      ),
2677      'private' => array(
2678        'name' => t('Private files'),
2679        'class' => 'DrupalPrivateStreamWrapper',
2680        'description' => t('Private local files served by Drupal.'),
2681        'type' => STREAM_WRAPPERS_LOCAL_NORMAL,
2682      ),
2683      'temp' => array(
2684        'name' => t('Temporary files'),
2685        'class' => 'DrupalTempStreamWrapper',
2686        'description' => t('Temporary local files for upload and previews.'),
2687        'type' => STREAM_WRAPPERS_LOCAL_HIDDEN,
2688      ),
2689      'cdn' => array(
2690        'name' => t('Content delivery network files'),
2691        'class' => 'MyModuleCDNStreamWrapper',
2692        'description' => t('Files served by a content delivery network.'),
2693        // 'type' can be omitted to use the default of STREAM_WRAPPERS_NORMAL
2694      ),
2695      'youtube' => array(
2696        'name' => t('YouTube video'),
2697        'class' => 'MyModuleYouTubeStreamWrapper',
2698        'description' => t('Video streamed from YouTube.'),
2699        // A module implementing YouTube integration may decide to support using
2700        // the YouTube API for uploading video, but here, we assume that this
2701        // particular module only supports playing YouTube video.
2702        'type' => STREAM_WRAPPERS_READ_VISIBLE,
2703      ),
2704    );
2705  }
2706  
2707  /**
2708   * Alters the list of PHP stream wrapper implementations.
2709   *
2710   * @see file_get_stream_wrappers()
2711   * @see hook_stream_wrappers()
2712   */
2713  function hook_stream_wrappers_alter(&$wrappers) {
2714    // Change the name of private files to reflect the performance.
2715    $wrappers['private']['name'] = t('Slow files');
2716  }
2717  
2718  /**
2719   * Load additional information into file objects.
2720   *
2721   * file_load_multiple() calls this hook to allow modules to load
2722   * additional information into each file.
2723   *
2724   * @param $files
2725   *   An array of file objects, indexed by fid.
2726   *
2727   * @see file_load_multiple()
2728   * @see file_load()
2729   */
2730  function hook_file_load($files) {
2731    // Add the upload specific data into the file object.
2732    $result = db_query('SELECT * FROM {upload} u WHERE u.fid IN (:fids)', array(':fids' => array_keys($files)))->fetchAll(PDO::FETCH_ASSOC);
2733    foreach ($result as $record) {
2734      foreach ($record as $key => $value) {
2735        $files[$record['fid']]->$key = $value;
2736      }
2737    }
2738  }
2739  
2740  /**
2741   * Check that files meet a given criteria.
2742   *
2743   * This hook lets modules perform additional validation on files. They're able
2744   * to report a failure by returning one or more error messages.
2745   *
2746   * @param $file
2747   *   The file object being validated.
2748   * @return
2749   *   An array of error messages. If there are no problems with the file return
2750   *   an empty array.
2751   *
2752   * @see file_validate()
2753   */
2754  function hook_file_validate($file) {
2755    $errors = array();
2756  
2757    if (empty($file->filename)) {
2758      $errors[] = t("The file's name is empty. Please give a name to the file.");
2759    }
2760    if (strlen($file->filename) > 255) {
2761      $errors[] = t("The file's name exceeds the 255 characters limit. Please rename the file and try again.");
2762    }
2763  
2764    return $errors;
2765  }
2766  
2767  /**
2768   * Act on a file being inserted or updated.
2769   *
2770   * This hook is called when a file has been added to the database. The hook
2771   * doesn't distinguish between files created as a result of a copy or those
2772   * created by an upload.
2773   *
2774   * @param $file
2775   *   The file that has just been created.
2776   *
2777   * @see file_save()
2778   */
2779  function hook_file_presave($file) {
2780    // Change the file timestamp to an hour prior.
2781    $file->timestamp -= 3600;
2782  }
2783  
2784  /**
2785   * Respond to a file being added.
2786   *
2787   * This hook is called after a file has been added to the database. The hook
2788   * doesn't distinguish between files created as a result of a copy or those
2789   * created by an upload.
2790   *
2791   * @param $file
2792   *   The file that has been added.
2793   *
2794   * @see file_save()
2795   */
2796  function hook_file_insert($file) {
2797    // Add a message to the log, if the file is a jpg
2798    $validate = file_validate_extensions($file, 'jpg');
2799    if (empty($validate)) {
2800      watchdog('file', 'A jpg has been added.');
2801    }
2802  }
2803  
2804  /**
2805   * Respond to a file being updated.
2806   *
2807   * This hook is called when file_save() is called on an existing file.
2808   *
2809   * @param $file
2810   *   The file that has just been updated.
2811   *
2812   * @see file_save()
2813   */
2814  function hook_file_update($file) {
2815  
2816  }
2817  
2818  /**
2819   * Respond to a file that has been copied.
2820   *
2821   * @param $file
2822   *   The newly copied file object.
2823   * @param $source
2824   *   The original file before the copy.
2825   *
2826   * @see file_copy()
2827   */
2828  function hook_file_copy($file, $source) {
2829  
2830  }
2831  
2832  /**
2833   * Respond to a file that has been moved.
2834   *
2835   * @param $file
2836   *   The updated file object after the move.
2837   * @param $source
2838   *   The original file object before the move.
2839   *
2840   * @see file_move()
2841   */
2842  function hook_file_move($file, $source) {
2843  
2844  }
2845  
2846  /**
2847   * Respond to a file being deleted.
2848   *
2849   * @param $file
2850   *   The file that has just been deleted.
2851   *
2852   * @see file_delete()
2853   */
2854  function hook_file_delete($file) {
2855    // Delete all information associated with the file.
2856    db_delete('upload')->condition('fid', $file->fid)->execute();
2857  }
2858  
2859  /**
2860   * Control access to private file downloads and specify HTTP headers.
2861   *
2862   * This hook allows modules enforce permissions on file downloads when the
2863   * private file download method is selected. Modules can also provide headers
2864   * to specify information like the file's name or MIME type.
2865   *
2866   * @param $uri
2867   *   The URI of the file.
2868   * @return
2869   *   If the user does not have permission to access the file, return -1. If the
2870   *   user has permission, return an array with the appropriate headers. If the
2871   *   file is not controlled by the current module, the return value should be
2872   *   NULL.
2873   *
2874   * @see file_download()
2875   */
2876  function hook_file_download($uri) {
2877    // Check if the file is controlled by the current module.
2878    if (!file_prepare_directory($uri)) {
2879      $uri = FALSE;
2880    }
2881    if (strpos(file_uri_target($uri), variable_get('user_picture_path', 'pictures') . '/picture-') === 0) {
2882      if (!user_access('access user profiles')) {
2883        // Access to the file is denied.
2884        return -1;
2885      }
2886      else {
2887        $info = image_get_info($uri);
2888        return array('Content-Type' => $info['mime_type']);
2889      }
2890    }
2891  }
2892  
2893  /**
2894   * Alter the URL to a file.
2895   *
2896   * This hook is called from file_create_url(), and  is called fairly
2897   * frequently (10+ times per page), depending on how many files there are in a
2898   * given page.
2899   * If CSS and JS aggregation are disabled, this can become very frequently
2900   * (50+ times per page) so performance is critical.
2901   *
2902   * This function should alter the URI, if it wants to rewrite the file URL.
2903   *
2904   * @param $uri
2905   *   The URI to a file for which we need an external URL, or the path to a
2906   *   shipped file.
2907   */
2908  function hook_file_url_alter(&$uri) {
2909    global $user;
2910  
2911    // User 1 will always see the local file in this example.
2912    if ($user->uid == 1) {
2913      return;
2914    }
2915  
2916    $cdn1 = 'http://cdn1.example.com';
2917    $cdn2 = 'http://cdn2.example.com';
2918    $cdn_extensions = array('css', 'js', 'gif', 'jpg', 'jpeg', 'png');
2919  
2920    // Most CDNs don't support private file transfers without a lot of hassle,
2921    // so don't support this in the common case.
2922    $schemes = array('public');
2923  
2924    $scheme = file_uri_scheme($uri);
2925  
2926    // Only serve shipped files and public created files from the CDN.
2927    if (!$scheme || in_array($scheme, $schemes)) {
2928      // Shipped files.
2929      if (!$scheme) {
2930        $path = $uri;
2931      }
2932      // Public created files.
2933      else {
2934        $wrapper = file_stream_wrapper_get_instance_by_scheme($scheme);
2935        $path = $wrapper->getDirectoryPath() . '/' . file_uri_target($uri);
2936      }
2937  
2938      // Clean up Windows paths.
2939      $path = str_replace('\\', '/', $path);
2940  
2941      // Serve files with one of the CDN extensions from CDN 1, all others from
2942      // CDN 2.
2943      $pathinfo = pathinfo($path);
2944      if (isset($pathinfo['extension']) && in_array($pathinfo['extension'], $cdn_extensions)) {
2945        $uri = $cdn1 . '/' . $path;
2946      }
2947      else {
2948        $uri = $cdn2 . '/' . $path;
2949      }
2950    }
2951  }
2952  
2953  /**
2954   * Check installation requirements and do status reporting.
2955   *
2956   * This hook has three closely related uses, determined by the $phase argument:
2957   * - Checking installation requirements ($phase == 'install').
2958   * - Checking update requirements ($phase == 'update').
2959   * - Status reporting ($phase == 'runtime').
2960   *
2961   * Note that this hook, like all others dealing with installation and updates,
2962   * must reside in a module_name.install file, or it will not properly abort
2963   * the installation of the module if a critical requirement is missing.
2964   *
2965   * During the 'install' phase, modules can for example assert that
2966   * library or server versions are available or sufficient.
2967   * Note that the installation of a module can happen during installation of
2968   * Drupal itself (by install.php) with an installation profile or later by hand.
2969   * As a consequence, install-time requirements must be checked without access
2970   * to the full Drupal API, because it is not available during install.php.
2971   * For localization you should for example use $t = get_t() to
2972   * retrieve the appropriate localization function name (t() or st()).
2973   * If a requirement has a severity of REQUIREMENT_ERROR, install.php will abort
2974   * or at least the module will not install.
2975   * Other severity levels have no effect on the installation.
2976   * Module dependencies do not belong to these installation requirements,
2977   * but should be defined in the module's .info file.
2978   *
2979   * The 'runtime' phase is not limited to pure installation requirements
2980   * but can also be used for more general status information like maintenance
2981   * tasks and security issues.
2982   * The returned 'requirements' will be listed on the status report in the
2983   * administration section, with indication of the severity level.
2984   * Moreover, any requirement with a severity of REQUIREMENT_ERROR severity will
2985   * result in a notice on the administration configuration page.
2986   *
2987   * @param $phase
2988   *   The phase in which requirements are checked:
2989   *   - install: The module is being installed.
2990   *   - update: The module is enabled and update.php is run.
2991   *   - runtime: The runtime requirements are being checked and shown on the
2992   *     status report page.
2993   *
2994   * @return
2995   *   A keyed array of requirements. Each requirement is itself an array with
2996   *   the following items:
2997   *   - title: The name of the requirement.
2998   *   - value: The current value (e.g., version, time, level, etc). During
2999   *     install phase, this should only be used for version numbers, do not set
3000   *     it if not applicable.
3001   *   - description: The description of the requirement/status.
3002   *   - severity: The requirement's result/severity level, one of:
3003   *     - REQUIREMENT_INFO: For info only.
3004   *     - REQUIREMENT_OK: The requirement is satisfied.
3005   *     - REQUIREMENT_WARNING: The requirement failed with a warning.
3006   *     - REQUIREMENT_ERROR: The requirement failed with an error.
3007   */
3008  function hook_requirements($phase) {
3009    $requirements = array();
3010    // Ensure translations don't break during installation.
3011    $t = get_t();
3012  
3013    // Report Drupal version
3014    if ($phase == 'runtime') {
3015      $requirements['drupal'] = array(
3016        'title' => $t('Drupal'),
3017        'value' => VERSION,
3018        'severity' => REQUIREMENT_INFO
3019      );
3020    }
3021  
3022    // Test PHP version
3023    $requirements['php'] = array(
3024      'title' => $t('PHP'),
3025      'value' => ($phase == 'runtime') ? l(phpversion(), 'admin/reports/status/php') : phpversion(),
3026    );
3027    if (version_compare(phpversion(), DRUPAL_MINIMUM_PHP) < 0) {
3028      $requirements['php']['description'] = $t('Your PHP installation is too old. Drupal requires at least PHP %version.', array('%version' => DRUPAL_MINIMUM_PHP));
3029      $requirements['php']['severity'] = REQUIREMENT_ERROR;
3030    }
3031  
3032    // Report cron status
3033    if ($phase == 'runtime') {
3034      $cron_last = variable_get('cron_last');
3035  
3036      if (is_numeric($cron_last)) {
3037        $requirements['cron']['value'] = $t('Last run !time ago', array('!time' => format_interval(REQUEST_TIME - $cron_last)));
3038      }
3039      else {
3040        $requirements['cron'] = array(
3041          'description' => $t('Cron has not run. It appears cron jobs have not been setup on your system. Check the help pages for <a href="@url">configuring cron jobs</a>.', array('@url' => 'http://drupal.org/cron')),
3042          'severity' => REQUIREMENT_ERROR,
3043          'value' => $t('Never run'),
3044        );
3045      }
3046  
3047      $requirements['cron']['description'] .= ' ' . $t('You can <a href="@cron">run cron manually</a>.', array('@cron' => url('admin/reports/status/run-cron')));
3048  
3049      $requirements['cron']['title'] = $t('Cron maintenance tasks');
3050    }
3051  
3052    return $requirements;
3053  }
3054  
3055  /**
3056   * Define the current version of the database schema.
3057   *
3058   * A Drupal schema definition is an array structure representing one or
3059   * more tables and their related keys and indexes. A schema is defined by
3060   * hook_schema() which must live in your module's .install file.
3061   *
3062   * This hook is called at install and uninstall time, and in the latter
3063   * case, it cannot rely on the .module file being loaded or hooks being known.
3064   * If the .module file is needed, it may be loaded with drupal_load().
3065   *
3066   * The tables declared by this hook will be automatically created when
3067   * the module is first enabled, and removed when the module is uninstalled.
3068   * This happens before hook_install() is invoked, and after hook_uninstall()
3069   * is invoked, respectively.
3070   *
3071   * By declaring the tables used by your module via an implementation of
3072   * hook_schema(), these tables will be available on all supported database
3073   * engines. You don't have to deal with the different SQL dialects for table
3074   * creation and alteration of the supported database engines.
3075   *
3076   * See the Schema API Handbook at http://drupal.org/node/146843 for
3077   * details on schema definition structures.
3078   *
3079   * @return
3080   *   A schema definition structure array. For each element of the
3081   *   array, the key is a table name and the value is a table structure
3082   *   definition.
3083   *
3084   * @ingroup schemaapi
3085   */
3086  function hook_schema() {
3087    $schema['node'] = array(
3088      // example (partial) specification for table "node"
3089      'description' => 'The base table for nodes.',
3090      'fields' => array(
3091        'nid' => array(
3092          'description' => 'The primary identifier for a node.',
3093          'type' => 'serial',
3094          'unsigned' => TRUE,
3095          'not null' => TRUE),
3096        'vid' => array(
3097          'description' => 'The current {node_revision}.vid version identifier.',
3098          'type' => 'int',
3099          'unsigned' => TRUE,
3100          'not null' => TRUE,
3101          'default' => 0),
3102        'type' => array(
3103          'description' => 'The {node_type} of this node.',
3104          'type' => 'varchar',
3105          'length' => 32,
3106          'not null' => TRUE,
3107          'default' => ''),
3108        'title' => array(
3109          'description' => 'The title of this node, always treated as non-markup plain text.',
3110          'type' => 'varchar',
3111          'length' => 255,
3112          'not null' => TRUE,
3113          'default' => ''),
3114        ),
3115      'indexes' => array(
3116        'node_changed'        => array('changed'),
3117        'node_created'        => array('created'),
3118        ),
3119      'unique keys' => array(
3120        'nid_vid' => array('nid', 'vid'),
3121        'vid'     => array('vid')
3122        ),
3123      'foreign keys' => array(
3124        'node_revision' => array(
3125          'table' => 'node_revision',
3126          'columns' => array('vid' => 'vid'),
3127          ),
3128        'node_author' => array(
3129          'table' => 'users',
3130          'columns' => array('uid' => 'uid')
3131          ),
3132         ),
3133      'primary key' => array('nid'),
3134    );
3135    return $schema;
3136  }
3137  
3138  /**
3139   * Perform alterations to existing database schemas.
3140   *
3141   * When a module modifies the database structure of another module (by
3142   * changing, adding or removing fields, keys or indexes), it should
3143   * implement hook_schema_alter() to update the default $schema to take its
3144   * changes into account.
3145   *
3146   * See hook_schema() for details on the schema definition structure.
3147   *
3148   * @param $schema
3149   *   Nested array describing the schemas for all modules.
3150   */
3151  function hook_schema_alter(&$schema) {
3152    // Add field to existing schema.
3153    $schema['users']['fields']['timezone_id'] = array(
3154      'type' => 'int',
3155      'not null' => TRUE,
3156      'default' => 0,
3157      'description' => 'Per-user timezone configuration.',
3158    );
3159  }
3160  
3161  /**
3162   * Perform alterations to a structured query.
3163   *
3164   * Structured (aka dynamic) queries that have tags associated may be altered by any module
3165   * before the query is executed.
3166   *
3167   * @param $query
3168   *   A Query object describing the composite parts of a SQL query.
3169   *
3170   * @see hook_query_TAG_alter()
3171   * @see node_query_node_access_alter()
3172   * @see QueryAlterableInterface
3173   * @see SelectQueryInterface
3174   */
3175  function hook_query_alter(QueryAlterableInterface $query) {
3176    if ($query->hasTag('micro_limit')) {
3177      $query->range(0, 2);
3178    }
3179  }
3180  
3181  /**
3182   * Perform alterations to a structured query for a given tag.
3183   *
3184   * @param $query
3185   *   An Query object describing the composite parts of a SQL query.
3186   *
3187   * @see hook_query_alter()
3188   * @see node_query_node_access_alter()
3189   * @see QueryAlterableInterface
3190   * @see SelectQueryInterface
3191   */
3192  function hook_query_TAG_alter(QueryAlterableInterface $query) {
3193    // Skip the extra expensive alterations if site has no node access control modules.
3194    if (!node_access_view_all_nodes()) {
3195      // Prevent duplicates records.
3196      $query->distinct();
3197      // The recognized operations are 'view', 'update', 'delete'.
3198      if (!$op = $query->getMetaData('op')) {
3199        $op = 'view';
3200      }
3201      // Skip the extra joins and conditions for node admins.
3202      if (!user_access('bypass node access')) {
3203        // The node_access table has the access grants for any given node.
3204        $access_alias = $query->join('node_access', 'na', '%alias.nid = n.nid');
3205        $or = db_or();
3206        // If any grant exists for the specified user, then user has access to the node for the specified operation.
3207        foreach (node_access_grants($op, $query->getMetaData('account')) as $realm => $gids) {
3208          foreach ($gids as $gid) {
3209            $or->condition(db_and()
3210              ->condition($access_alias . '.gid', $gid)
3211              ->condition($access_alias . '.realm', $realm)
3212            );
3213          }
3214        }
3215  
3216        if (count($or->conditions())) {
3217          $query->condition($or);
3218        }
3219  
3220        $query->condition($access_alias . 'grant_' . $op, 1, '>=');
3221      }
3222    }
3223  }
3224  
3225  /**
3226   * Perform setup tasks when the module is installed.
3227   *
3228   * If the module implements hook_schema(), the database tables will
3229   * be created before this hook is fired.
3230   *
3231   * Implementations of this hook are by convention declared in the module's
3232   * .install file. The implementation can rely on the .module file being loaded.
3233   * The hook will only be called the first time a module is enabled or after it
3234   * is re-enabled after being uninstalled. The module's schema version will be
3235   * set to the module's greatest numbered update hook. Because of this, any time
3236   * a hook_update_N() is added to the module, this function needs to be updated
3237   * to reflect the current version of the database schema.
3238   *
3239   * See the Schema API documentation at
3240   * @link http://drupal.org/node/146843 http://drupal.org/node/146843 @endlink
3241   * for details on hook_schema and how database tables are defined.
3242   *
3243   * Note that since this function is called from a full bootstrap, all functions
3244   * (including those in modules enabled by the current page request) are
3245   * available when this hook is called. Use cases could be displaying a user
3246   * message, or calling a module function necessary for initial setup, etc.
3247   *
3248   * Please be sure that anything added or modified in this function that can
3249   * be removed during uninstall should be removed with hook_uninstall().
3250   *
3251   * @see hook_schema()
3252   * @see module_enable()
3253   * @see hook_enable()
3254   * @see hook_disable()
3255   * @see hook_uninstall()
3256   * @see hook_modules_installed()
3257   */
3258  function hook_install() {
3259    // Populate the default {node_access} record.
3260    db_insert('node_access')
3261      ->fields(array(
3262        'nid' => 0,
3263        'gid' => 0,
3264        'realm' => 'all',
3265        'grant_view' => 1,
3266        'grant_update' => 0,
3267        'grant_delete' => 0,
3268      ))
3269      ->execute();
3270  }
3271  
3272  /**
3273   * Perform a single update.
3274   *
3275   * For each change that requires one or more actions to be performed when
3276   * updating a site, add a new hook_update_N(), which will be called by
3277   * update.php. The documentation block preceding this function is stripped of
3278   * newlines and used as the description for the update on the pending updates
3279   * task list. Schema updates should adhere to the
3280   * @link http://drupal.org/node/150215 Schema API. @endlink
3281   *
3282   * Implementations of hook_update_N() are named (module name)_update_(number).
3283   * The numbers are composed of three parts:
3284   * - 1 digit for Drupal core compatibility.
3285   * - 1 digit for your module's major release version (e.g., is this the 7.x-1.*
3286   *   (1) or 7.x-2.* (2) series of your module?). This digit should be 0 for
3287   *   initial porting of your module to a new Drupal core API.
3288   * - 2 digits for sequential counting, starting with 00.
3289   *
3290   * Examples:
3291   * - mymodule_update_7000(): This is the required update for mymodule to run
3292   *   with Drupal core API 7.x when upgrading from Drupal core API 6.x.
3293   * - mymodule_update_7100(): This is the first update to get the database ready
3294   *   to run mymodule 7.x-1.*.
3295   * - mymodule_update_7200(): This is the first update to get the database ready
3296   *   to run mymodule 7.x-2.*. Users can directly update from 6.x-2.* to 7.x-2.*
3297   *   and they get all 70xx and 72xx updates, but not 71xx updates, because
3298   *   those reside in the 7.x-1.x branch only.
3299   *
3300   * A good rule of thumb is to remove updates older than two major releases of
3301   * Drupal. See hook_update_last_removed() to notify Drupal about the removals.
3302   * For further information about releases and release numbers see:
3303   * @link http://drupal.org/node/711070 Maintaining a drupal.org project with Git @endlink
3304   *
3305   * Never renumber update functions.
3306   *
3307   * Implementations of this hook should be placed in a mymodule.install file in
3308   * the same directory as mymodule.module. Drupal core's updates are implemented
3309   * using the system module as a name and stored in database/updates.inc.
3310   *
3311   * Not all module functions are available from within a hook_update_N() function.
3312   * In order to call a function from your mymodule.module or an include file,
3313   * you need to explicitly load that file first.
3314   *
3315   * During database updates the schema of any module could be out of date. For
3316   * this reason, caution is needed when using any API function within an update
3317   * function - particularly CRUD functions, functions that depend on the schema
3318   * (for example by using drupal_write_record()), and any functions that invoke
3319   * hooks. See @link update_api Update versions of API functions @endlink for
3320   * details.
3321   *
3322   * If your update task is potentially time-consuming, you'll need to implement a
3323   * multipass update to avoid PHP timeouts. Multipass updates use the $sandbox
3324   * parameter provided by the batch API (normally, $context['sandbox']) to store
3325   * information between successive calls, and the $sandbox['#finished'] value
3326   * to provide feedback regarding completion level.
3327   *
3328   * See the batch operations page for more information on how to use the
3329   * @link http://drupal.org/node/180528 Batch API. @endlink
3330   *
3331   * @param $sandbox
3332   *   Stores information for multipass updates. See above for more information.
3333   *
3334   * @throws DrupalUpdateException, PDOException
3335   *   In case of error, update hooks should throw an instance of DrupalUpdateException
3336   *   with a meaningful message for the user. If a database query fails for whatever
3337   *   reason, it will throw a PDOException.
3338   *
3339   * @return
3340   *   Optionally, update hooks may return a translated string that will be
3341   *   displayed to the user after the update has completed. If no message is
3342   *   returned, no message will be presented to the user.
3343   *
3344   * @see batch
3345   * @see schemaapi
3346   * @see update_api
3347   * @see hook_update_last_removed()
3348   * @see update_get_update_list()
3349   */
3350  function hook_update_N(&$sandbox) {
3351    // For non-multipass updates, the signature can simply be;
3352    // function hook_update_N() {
3353  
3354    // For most updates, the following is sufficient.
3355    db_add_field('mytable1', 'newcol', array('type' => 'int', 'not null' => TRUE, 'description' => 'My new integer column.'));
3356  
3357    // However, for more complex operations that may take a long time,
3358    // you may hook into Batch API as in the following example.
3359  
3360    // Update 3 users at a time to have an exclamation point after their names.
3361    // (They're really happy that we can do batch API in this hook!)
3362    if (!isset($sandbox['progress'])) {
3363      $sandbox['progress'] = 0;
3364      $sandbox['current_uid'] = 0;
3365      // We'll -1 to disregard the uid 0...
3366      $sandbox['max'] = db_query('SELECT COUNT(DISTINCT uid) FROM {users}')->fetchField() - 1;
3367    }
3368  
3369    $users = db_select('users', 'u')
3370      ->fields('u', array('uid', 'name'))
3371      ->condition('uid', $sandbox['current_uid'], '>')
3372      ->range(0, 3)
3373      ->orderBy('uid', 'ASC')
3374      ->execute();
3375  
3376    foreach ($users as $user) {
3377      $user->name .= '!';
3378      db_update('users')
3379        ->fields(array('name' => $user->name))
3380        ->condition('uid', $user->uid)
3381        ->execute();
3382  
3383      $sandbox['progress']++;
3384      $sandbox['current_uid'] = $user->uid;
3385    }
3386  
3387    $sandbox['#finished'] = empty($sandbox['max']) ? 1 : ($sandbox['progress'] / $sandbox['max']);
3388  
3389    // To display a message to the user when the update is completed, return it.
3390    // If you do not want to display a completion message, simply return nothing.
3391    return t('The update did what it was supposed to do.');
3392  
3393    // In case of an error, simply throw an exception with an error message.
3394    throw new DrupalUpdateException('Something went wrong; here is what you should do.');
3395  }
3396  
3397  /**
3398   * Return an array of information about module update dependencies.
3399   *
3400   * This can be used to indicate update functions from other modules that your
3401   * module's update functions depend on, or vice versa. It is used by the update
3402   * system to determine the appropriate order in which updates should be run, as
3403   * well as to search for missing dependencies.
3404   *
3405   * Implementations of this hook should be placed in a mymodule.install file in
3406   * the same directory as mymodule.module.
3407   *
3408   * @return
3409   *   A multidimensional array containing information about the module update
3410   *   dependencies. The first two levels of keys represent the module and update
3411   *   number (respectively) for which information is being returned, and the
3412   *   value is an array of information about that update's dependencies. Within
3413   *   this array, each key represents a module, and each value represents the
3414   *   number of an update function within that module. In the event that your
3415   *   update function depends on more than one update from a particular module,
3416   *   you should always list the highest numbered one here (since updates within
3417   *   a given module always run in numerical order).
3418   *
3419   * @see update_resolve_dependencies()
3420   * @see hook_update_N()
3421   */
3422  function hook_update_dependencies() {
3423    // Indicate that the mymodule_update_7000() function provided by this module
3424    // must run after the another_module_update_7002() function provided by the
3425    // 'another_module' module.
3426    $dependencies['mymodule'][7000] = array(
3427      'another_module' => 7002,
3428    );
3429    // Indicate that the mymodule_update_7001() function provided by this module
3430    // must run before the yet_another_module_update_7004() function provided by
3431    // the 'yet_another_module' module. (Note that declaring dependencies in this
3432    // direction should be done only in rare situations, since it can lead to the
3433    // following problem: If a site has already run the yet_another_module
3434    // module's database updates before it updates its codebase to pick up the
3435    // newest mymodule code, then the dependency declared here will be ignored.)
3436    $dependencies['yet_another_module'][7004] = array(
3437      'mymodule' => 7001,
3438    );
3439    return $dependencies;
3440  }
3441  
3442  /**
3443   * Return a number which is no longer available as hook_update_N().
3444   *
3445   * If you remove some update functions from your mymodule.install file, you
3446   * should notify Drupal of those missing functions. This way, Drupal can
3447   * ensure that no update is accidentally skipped.
3448   *
3449   * Implementations of this hook should be placed in a mymodule.install file in
3450   * the same directory as mymodule.module.
3451   *
3452   * @return
3453   *   An integer, corresponding to hook_update_N() which has been removed from
3454   *   mymodule.install.
3455   *
3456   * @see hook_update_N()
3457   */
3458  function hook_update_last_removed() {
3459    // We've removed the 5.x-1.x version of mymodule, including database updates.
3460    // The next update function is mymodule_update_5200().
3461    return 5103;
3462  }
3463  
3464  /**
3465   * Remove any information that the module sets.
3466   *
3467   * The information that the module should remove includes:
3468   * - variables that the module has set using variable_set() or system_settings_form()
3469   * - modifications to existing tables
3470   *
3471   * The module should not remove its entry from the {system} table. Database
3472   * tables defined by hook_schema() will be removed automatically.
3473   *
3474   * The uninstall hook must be implemented in the module's .install file. It
3475   * will fire when the module gets uninstalled but before the module's database
3476   * tables are removed, allowing your module to query its own tables during
3477   * this routine.
3478   *
3479   * When hook_uninstall() is called, your module will already be disabled, so
3480   * its .module file will not be automatically included. If you need to call API
3481   * functions from your .module file in this hook, use drupal_load() to make
3482   * them available. (Keep this usage to a minimum, though, especially when
3483   * calling API functions that invoke hooks, or API functions from modules
3484   * listed as dependencies, since these may not be available or work as expected
3485   * when the module is disabled.)
3486   *
3487   * @see hook_install()
3488   * @see hook_schema()
3489   * @see hook_disable()
3490   * @see hook_modules_uninstalled()
3491   */
3492  function hook_uninstall() {
3493    variable_del('upload_file_types');
3494  }
3495  
3496  /**
3497   * Perform necessary actions after module is enabled.
3498   *
3499   * The hook is called every time the module is enabled. It should be
3500   * implemented in the module's .install file. The implementation can
3501   * rely on the .module file being loaded.
3502   *
3503   * @see module_enable()
3504   * @see hook_install()
3505   * @see hook_modules_enabled()
3506   */
3507  function hook_enable() {
3508    mymodule_cache_rebuild();
3509  }
3510  
3511  /**
3512   * Perform necessary actions before module is disabled.
3513   *
3514   * The hook is called every time the module is disabled. It should be
3515   * implemented in the module's .install file. The implementation can rely
3516   * on the .module file being loaded.
3517   *
3518   * @see hook_uninstall()
3519   * @see hook_modules_disabled()
3520   */
3521  function hook_disable() {
3522    mymodule_cache_rebuild();
3523  }
3524  
3525  /**
3526   * Perform necessary alterations to the list of files parsed by the registry.
3527   *
3528   * Modules can manually modify the list of files before the registry parses
3529   * them. The $modules array provides the .info file information, which includes
3530   * the list of files registered to each module. Any files in the list can then
3531   * be added to the list of files that the registry will parse, or modify
3532   * attributes of a file.
3533   *
3534   * A necessary alteration made by the core SimpleTest module is to force .test
3535   * files provided by disabled modules into the list of files parsed by the
3536   * registry.
3537   *
3538   * @param $files
3539   *   List of files to be parsed by the registry. The list will contain
3540   *   files found in each enabled module's info file and the core includes
3541   *   directory. The array is keyed by the file path and contains an array of
3542   *   the related module's name and weight as used internally by
3543   *   _registry_update() and related functions.
3544   *
3545   *   For example:
3546   *   @code
3547   *     $files["modules/system/system.module"] = array(
3548   *       'module' => 'system',
3549   *       'weight' => 0,
3550   *     );
3551   *   @endcode
3552   * @param $modules
3553   *   An array containing all module information stored in the {system} table.
3554   *   Each element of the array also contains the module's .info file
3555   *   information in the property 'info'. An additional 'dir' property has been
3556   *   added to the module information which provides the path to the directory
3557   *   in which the module resides. The example shows how to take advantage of
3558   *   both properties.
3559   *
3560   * @see _registry_update()
3561   * @see simpletest_test_get_all()
3562   */
3563  function hook_registry_files_alter(&$files, $modules) {
3564    foreach ($modules as $module) {
3565      // Only add test files for disabled modules, as enabled modules should
3566      // already include any test files they provide.
3567      if (!$module->status) {
3568        $dir = $module->dir;
3569        foreach ($module->info['files'] as $file) {
3570          if (substr($file, -5) == '.test') {
3571            $files["$dir/$file"] = array('module' => $module->name, 'weight' => $module->weight);
3572          }
3573        }
3574      }
3575    }
3576  }
3577  
3578  /**
3579   * Return an array of tasks to be performed by an installation profile.
3580   *
3581   * Any tasks you define here will be run, in order, after the installer has
3582   * finished the site configuration step but before it has moved on to the
3583   * final import of languages and the end of the installation. You can have any
3584   * number of custom tasks to perform during this phase.
3585   *
3586   * Each task you define here corresponds to a callback function which you must
3587   * separately define and which is called when your task is run. This function
3588   * will receive the global installation state variable, $install_state, as
3589   * input, and has the opportunity to access or modify any of its settings. See
3590   * the install_state_defaults() function in the installer for the list of
3591   * $install_state settings used by Drupal core.
3592   *
3593   * At the end of your task function, you can indicate that you want the
3594   * installer to pause and display a page to the user by returning any themed
3595   * output that should be displayed on that page (but see below for tasks that
3596   * use the form API or batch API; the return values of these task functions are
3597   * handled differently). You should also use drupal_set_title() within the task
3598   * callback function to set a custom page title. For some tasks, however, you
3599   * may want to simply do some processing and pass control to the next task
3600   * without ending the page request; to indicate this, simply do not send back
3601   * a return value from your task function at all. This can be used, for
3602   * example, by installation profiles that need to configure certain site
3603   * settings in the database without obtaining any input from the user.
3604   *
3605   * The task function is treated specially if it defines a form or requires
3606   * batch processing; in that case, you should return either the form API
3607   * definition or batch API array, as appropriate. See below for more
3608   * information on the 'type' key that you must define in the task definition
3609   * to inform the installer that your task falls into one of those two
3610   * categories. It is important to use these APIs directly, since the installer
3611   * may be run non-interactively (for example, via a command line script), all
3612   * in one page request; in that case, the installer will automatically take
3613   * care of submitting forms and processing batches correctly for both types of
3614   * installations. You can inspect the $install_state['interactive'] boolean to
3615   * see whether or not the current installation is interactive, if you need
3616   * access to this information.
3617   *
3618   * Remember that a user installing Drupal interactively will be able to reload
3619   * an installation page multiple times, so you should use variable_set() and
3620   * variable_get() if you are collecting any data that you need to store and
3621   * inspect later. It is important to remove any temporary variables using
3622   * variable_del() before your last task has completed and control is handed
3623   * back to the installer.
3624   *
3625   * @return
3626   *   A keyed array of tasks the profile will perform during the final stage of
3627   *   the installation. Each key represents the name of a function (usually a
3628   *   function defined by this profile, although that is not strictly required)
3629   *   that is called when that task is run. The values are associative arrays
3630   *   containing the following key-value pairs (all of which are optional):
3631   *     - 'display_name'
3632   *       The human-readable name of the task. This will be displayed to the
3633   *       user while the installer is running, along with a list of other tasks
3634   *       that are being run. Leave this unset to prevent the task from
3635   *       appearing in the list.
3636   *     - 'display'
3637   *       This is a boolean which can be used to provide finer-grained control
3638   *       over whether or not the task will display. This is mostly useful for
3639   *       tasks that are intended to display only under certain conditions; for
3640   *       these tasks, you can set 'display_name' to the name that you want to
3641   *       display, but then use this boolean to hide the task only when certain
3642   *       conditions apply.
3643   *     - 'type'
3644   *       A string representing the type of task. This parameter has three
3645   *       possible values:
3646   *       - 'normal': This indicates that the task will be treated as a regular
3647   *       callback function, which does its processing and optionally returns
3648   *       HTML output. This is the default behavior which is used when 'type' is
3649   *       not set.
3650   *       - 'batch': This indicates that the task function will return a batch
3651   *       API definition suitable for batch_set(). The installer will then take
3652   *       care of automatically running the task via batch processing.
3653   *       - 'form': This indicates that the task function will return a standard
3654   *       form API definition (and separately define validation and submit
3655   *       handlers, as appropriate). The installer will then take care of
3656   *       automatically directing the user through the form submission process.
3657   *     - 'run'
3658   *       A constant representing the manner in which the task will be run. This
3659   *       parameter has three possible values:
3660   *       - INSTALL_TASK_RUN_IF_NOT_COMPLETED: This indicates that the task will
3661   *       run once during the installation of the profile. This is the default
3662   *       behavior which is used when 'run' is not set.
3663   *       - INSTALL_TASK_SKIP: This indicates that the task will not run during
3664   *       the current installation page request. It can be used to skip running
3665   *       an installation task when certain conditions are met, even though the
3666   *       task may still show on the list of installation tasks presented to the
3667   *       user.
3668   *       - INSTALL_TASK_RUN_IF_REACHED: This indicates that the task will run
3669   *       on each installation page request that reaches it. This is rarely
3670   *       necessary for an installation profile to use; it is primarily used by
3671   *       the Drupal installer for bootstrap-related tasks.
3672   *     - 'function'
3673   *       Normally this does not need to be set, but it can be used to force the
3674   *       installer to call a different function when the task is run (rather
3675   *       than the function whose name is given by the array key). This could be
3676   *       used, for example, to allow the same function to be called by two
3677   *       different tasks.
3678   *
3679   * @see install_state_defaults()
3680   * @see batch_set()
3681   */
3682  function hook_install_tasks() {
3683    // Here, we define a variable to allow tasks to indicate that a particular,
3684    // processor-intensive batch process needs to be triggered later on in the
3685    // installation.
3686    $myprofile_needs_batch_processing = variable_get('myprofile_needs_batch_processing', FALSE);
3687    $tasks = array(
3688      // This is an example of a task that defines a form which the user who is
3689      // installing the site will be asked to fill out. To implement this task,
3690      // your profile would define a function named myprofile_data_import_form()
3691      // as a normal form API callback function, with associated validation and
3692      // submit handlers. In the submit handler, in addition to saving whatever
3693      // other data you have collected from the user, you might also call
3694      // variable_set('myprofile_needs_batch_processing', TRUE) if the user has
3695      // entered data which requires that batch processing will need to occur
3696      // later on.
3697      'myprofile_data_import_form' => array(
3698        'display_name' => st('Data import options'),
3699        'type' => 'form',
3700      ),
3701      // Similarly, to implement this task, your profile would define a function
3702      // named myprofile_settings_form() with associated validation and submit
3703      // handlers. This form might be used to collect and save additional
3704      // information from the user that your profile needs. There are no extra
3705      // steps required for your profile to act as an "installation wizard"; you
3706      // can simply define as many tasks of type 'form' as you wish to execute,
3707      // and the forms will be presented to the user, one after another.
3708      'myprofile_settings_form' => array(
3709        'display_name' => st('Additional options'),
3710        'type' => 'form',
3711      ),
3712      // This is an example of a task that performs batch operations. To
3713      // implement this task, your profile would define a function named
3714      // myprofile_batch_processing() which returns a batch API array definition
3715      // that the installer will use to execute your batch operations. Due to the
3716      // 'myprofile_needs_batch_processing' variable used here, this task will be
3717      // hidden and skipped unless your profile set it to TRUE in one of the
3718      // previous tasks.
3719      'myprofile_batch_processing' => array(
3720        'display_name' => st('Import additional data'),
3721        'display' => $myprofile_needs_batch_processing,
3722        'type' => 'batch',
3723        'run' => $myprofile_needs_batch_processing ? INSTALL_TASK_RUN_IF_NOT_COMPLETED : INSTALL_TASK_SKIP,
3724      ),
3725      // This is an example of a task that will not be displayed in the list that
3726      // the user sees. To implement this task, your profile would define a
3727      // function named myprofile_final_site_setup(), in which additional,
3728      // automated site setup operations would be performed. Since this is the
3729      // last task defined by your profile, you should also use this function to
3730      // call variable_del('myprofile_needs_batch_processing') and clean up the
3731      // variable that was used above. If you want the user to pass to the final
3732      // Drupal installation tasks uninterrupted, return no output from this
3733      // function. Otherwise, return themed output that the user will see (for
3734      // example, a confirmation page explaining that your profile's tasks are
3735      // complete, with a link to reload the current page and therefore pass on
3736      // to the final Drupal installation tasks when the user is ready to do so).
3737      'myprofile_final_site_setup' => array(
3738      ),
3739    );
3740    return $tasks;
3741  }
3742  
3743  /**
3744   * Change the page the user is sent to by drupal_goto().
3745   *
3746   * @param $path
3747   *   A Drupal path or a full URL.
3748   * @param $options
3749   *   An associative array of additional URL options to pass to url().
3750   * @param $http_response_code
3751   *   The HTTP status code to use for the redirection. See drupal_goto() for more
3752   *   information.
3753   */
3754  function hook_drupal_goto_alter(&$path, &$options, &$http_response_code) {
3755    // A good addition to misery module.
3756    $http_response_code = 500;
3757  }
3758  
3759  /**
3760   * Alter XHTML HEAD tags before they are rendered by drupal_get_html_head().
3761   *
3762   * Elements available to be altered are only those added using
3763   * drupal_add_html_head_link() or drupal_add_html_head(). CSS and JS files
3764   * are handled using drupal_add_css() and drupal_add_js(), so the head links
3765   * for those files will not appear in the $head_elements array.
3766   *
3767   * @param $head_elements
3768   *   An array of renderable elements. Generally the values of the #attributes
3769   *   array will be the most likely target for changes.
3770   */
3771  function hook_html_head_alter(&$head_elements) {
3772    foreach ($head_elements as $key => $element) {
3773      if (isset($element['#attributes']['rel']) && $element['#attributes']['rel'] == 'canonical') {
3774        // I want a custom canonical URL.
3775        $head_elements[$key]['#attributes']['href'] = mymodule_canonical_url();
3776      }
3777    }
3778  }
3779  
3780  /**
3781   * Alter the full list of installation tasks.
3782   *
3783   * @param $tasks
3784   *   An array of all available installation tasks, including those provided by
3785   *   Drupal core. You can modify this array to change or replace any part of
3786   *   the Drupal installation process that occurs after the installation profile
3787   *   is selected.
3788   * @param $install_state
3789   *   An array of information about the current installation state.
3790   */
3791  function hook_install_tasks_alter(&$tasks, $install_state) {
3792    // Replace the "Choose language" installation task provided by Drupal core
3793    // with a custom callback function defined by this installation profile.
3794    $tasks['install_select_locale']['function'] = 'myprofile_locale_selection';
3795  }
3796  
3797  /**
3798   * Alter MIME type mappings used to determine MIME type from a file extension.
3799   *
3800   * This hook is run when file_mimetype_mapping() is called. It is used to
3801   * allow modules to add to or modify the default mapping from
3802   * file_default_mimetype_mapping().
3803   *
3804   * @param $mapping
3805   *   An array of mimetypes correlated to the extensions that relate to them.
3806   *   The array has 'mimetypes' and 'extensions' elements, each of which is an
3807   *   array.
3808   *
3809   * @see file_default_mimetype_mapping()
3810   */
3811  function hook_file_mimetype_mapping_alter(&$mapping) {
3812    // Add new MIME type 'drupal/info'.
3813    $mapping['mimetypes']['example_info'] = 'drupal/info';
3814    // Add new extension '.info' and map it to the 'drupal/info' MIME type.
3815    $mapping['extensions']['info'] = 'example_info';
3816    // Override existing extension mapping for '.ogg' files.
3817    $mapping['extensions']['ogg'] = 189;
3818  }
3819  
3820  /**
3821   * Declares information about actions.
3822   *
3823   * Any module can define actions, and then call actions_do() to make those
3824   * actions happen in response to events. The trigger module provides a user
3825   * interface for associating actions with module-defined triggers, and it makes
3826   * sure the core triggers fire off actions when their events happen.
3827   *
3828   * An action consists of two or three parts:
3829   * - an action definition (returned by this hook)
3830   * - a function which performs the action (which by convention is named
3831   *   MODULE_description-of-function_action)
3832   * - an optional form definition function that defines a configuration form
3833   *   (which has the name of the action function with '_form' appended to it.)
3834   *
3835   * The action function takes two to four arguments, which come from the input
3836   * arguments to actions_do().
3837   *
3838   * @return
3839   *   An associative array of action descriptions. The keys of the array
3840   *   are the names of the action functions, and each corresponding value
3841   *   is an associative array with the following key-value pairs:
3842   *   - 'type': The type of object this action acts upon. Core actions have types
3843   *     'node', 'user', 'comment', and 'system'.
3844   *   - 'label': The human-readable name of the action, which should be passed
3845   *     through the t() function for translation.
3846   *   - 'configurable': If FALSE, then the action doesn't require any extra
3847   *     configuration. If TRUE, then your module must define a form function with
3848   *     the same name as the action function with '_form' appended (e.g., the
3849   *     form for 'node_assign_owner_action' is 'node_assign_owner_action_form'.)
3850   *     This function takes $context as its only parameter, and is paired with
3851   *     the usual _submit function, and possibly a _validate function.
3852   *   - 'triggers': An array of the events (that is, hooks) that can trigger this
3853   *     action. For example: array('node_insert', 'user_update'). You can also
3854   *     declare support for any trigger by returning array('any') for this value.
3855   *   - 'behavior': (optional) A machine-readable array of behaviors of this
3856   *     action, used to signal additionally required actions that may need to be
3857   *     triggered. Currently recognized behaviors by Trigger module:
3858   *     - 'changes_property': If an action with this behavior is assigned to a
3859   *       trigger other than a "presave" hook, any save actions also assigned to
3860   *       this trigger are moved later in the list. If no save action is present,
3861   *       one will be added.
3862   *       Modules that are processing actions (like Trigger module) should take
3863   *       special care for the "presave" hook, in which case a dependent "save"
3864   *       action should NOT be invoked.
3865   *
3866   * @ingroup actions
3867   */
3868  function hook_action_info() {
3869    return array(
3870      'comment_unpublish_action' => array(
3871        'type' => 'comment',
3872        'label' => t('Unpublish comment'),
3873        'configurable' => FALSE,
3874        'behavior' => array('changes_property'),
3875        'triggers' => array('comment_presave', 'comment_insert', 'comment_update'),
3876      ),
3877      'comment_unpublish_by_keyword_action' => array(
3878        'type' => 'comment',
3879        'label' => t('Unpublish comment containing keyword(s)'),
3880        'configurable' => TRUE,
3881        'behavior' => array('changes_property'),
3882        'triggers' => array('comment_presave', 'comment_insert', 'comment_update'),
3883      ),
3884      'comment_save_action' => array(
3885        'type' => 'comment',
3886        'label' => t('Save comment'),
3887        'configurable' => FALSE,
3888        'triggers' => array('comment_insert', 'comment_update'),
3889      ),
3890    );
3891  }
3892  
3893  /**
3894   * Executes code after an action is deleted.
3895   *
3896   * @param $aid
3897   *   The action ID.
3898   */
3899  function hook_actions_delete($aid) {
3900    db_delete('actions_assignments')
3901      ->condition('aid', $aid)
3902      ->execute();
3903  }
3904  
3905  /**
3906   * Alters the actions declared by another module.
3907   *
3908   * Called by actions_list() to allow modules to alter the return values from
3909   * implementations of hook_action_info().
3910   *
3911   * @see trigger_example_action_info_alter()
3912   */
3913  function hook_action_info_alter(&$actions) {
3914    $actions['node_unpublish_action']['label'] = t('Unpublish and remove from public view.');
3915  }
3916  
3917  /**
3918   * Declare archivers to the system.
3919   *
3920   * An archiver is a class that is able to package and unpackage one or more files
3921   * into a single possibly compressed file.  Common examples of such files are
3922   * zip files and tar.gz files.  All archiver classes must implement
3923   * ArchiverInterface.
3924   *
3925   * Each entry should be keyed on a unique value, and specify three
3926   * additional keys:
3927   * - class: The name of the PHP class for this archiver.
3928   * - extensions: An array of file extensions that this archiver supports.
3929   * - weight: This optional key specifies the weight of this archiver.
3930   *   When mapping file extensions to archivers, the first archiver by
3931   *   weight found that supports the requested extension will be used.
3932   *
3933   * @see hook_archiver_info_alter()
3934   */
3935  function hook_archiver_info() {
3936    return array(
3937      'tar' => array(
3938        'class' => 'ArchiverTar',
3939        'extensions' => array('tar', 'tar.gz', 'tar.bz2'),
3940      ),
3941    );
3942  }
3943  
3944  /**
3945   * Alter archiver information declared by other modules.
3946   *
3947   * See hook_archiver_info() for a description of archivers and the archiver
3948   * information structure.
3949   *
3950   * @param $info
3951   *   Archiver information to alter (return values from hook_archiver_info()).
3952   */
3953  function hook_archiver_info_alter(&$info) {
3954    $info['tar']['extensions'][] = 'tgz';
3955  }
3956  
3957  /**
3958   * Define additional date types.
3959   *
3960   * Next to the 'long', 'medium' and 'short' date types defined in core, any
3961   * module can define additional types that can be used when displaying dates,
3962   * by implementing this hook. A date type is basically just a name for a date
3963   * format.
3964   *
3965   * Date types are used in the administration interface: a user can assign
3966   * date format types defined in hook_date_formats() to date types defined in
3967   * this hook. Once a format has been assigned by a user, the machine name of a
3968   * type can be used in the format_date() function to format a date using the
3969   * chosen formatting.
3970   *
3971   * To define a date type in a module and make sure a format has been assigned to
3972   * it, without requiring a user to visit the administrative interface, use
3973   * @code variable_set('date_format_' . $type, $format); @endcode
3974   * where $type is the machine-readable name defined here, and $format is a PHP
3975   * date format string.
3976   *
3977   * To avoid namespace collisions with date types defined by other modules, it is
3978   * recommended that each date type starts with the module name. A date type
3979   * can consist of letters, numbers and underscores.
3980   *
3981   * @return
3982   *   An array of date types where the keys are the machine-readable names and
3983   *   the values are the human-readable labels.
3984   *
3985   * @see hook_date_formats()
3986   * @see format_date()
3987   */
3988  function hook_date_format_types() {
3989    // Define the core date format types.
3990    return array(
3991      'long' => t('Long'),
3992      'medium' => t('Medium'),
3993      'short' => t('Short'),
3994    );
3995  }
3996  
3997  /**
3998   * Modify existing date types.
3999   *
4000   * Allows other modules to modify existing date types like 'long'. Called by
4001   * _system_date_format_types_build(). For instance, A module may use this hook
4002   * to apply settings across all date types, such as locking all date types so
4003   * they appear to be provided by the system.
4004   *
4005   * @param $types
4006   *   A list of date types. Each date type is keyed by the machine-readable name
4007   *   and the values are associative arrays containing:
4008   *   - is_new: Set to FALSE to override previous settings.
4009   *   - module: The name of the module that created the date type.
4010   *   - type: The machine-readable date type name.
4011   *   - title: The human-readable date type name.
4012   *   - locked: Specifies that the date type is system-provided.
4013   */
4014  function hook_date_format_types_alter(&$types) {
4015    foreach ($types as $name => $type) {
4016      $types[$name]['locked'] = 1;
4017    }
4018  }
4019  
4020  /**
4021   * Define additional date formats.
4022   *
4023   * This hook is used to define the PHP date format strings that can be assigned
4024   * to date types in the administrative interface. A module can provide date
4025   * format strings for the core-provided date types ('long', 'medium', and
4026   * 'short'), or for date types defined in hook_date_format_types() by itself
4027   * or another module.
4028   *
4029   * Since date formats can be locale-specific, you can specify the locales that
4030   * each date format string applies to. There may be more than one locale for a
4031   * format. There may also be more than one format for the same locale. For
4032   * example d/m/Y and Y/m/d work equally well in some locales. You may wish to
4033   * define some additional date formats that aren't specific to any one locale,
4034   * for example, "Y m". For these cases, the 'locales' component of the return
4035   * value should be omitted.
4036   *
4037   * Providing a date format here does not normally assign the format to be
4038   * used with the associated date type -- a user has to choose a format for each
4039   * date type in the administrative interface. There is one exception: locale
4040   * initialization chooses a locale-specific format for the three core-provided
4041   * types (see locale_get_localized_date_format() for details). If your module
4042   * needs to ensure that a date type it defines has a format associated with it,
4043   * call @code variable_set('date_format_' . $type, $format); @endcode
4044   * where $type is the machine-readable name defined in hook_date_format_types(),
4045   * and $format is a PHP date format string.
4046   *
4047   * @return
4048   *   A list of date formats to offer as choices in the administrative
4049   *   interface. Each date format is a keyed array consisting of three elements:
4050   *   - 'type': The date type name that this format can be used with, as
4051   *     declared in an implementation of hook_date_format_types().
4052   *   - 'format': A PHP date format string to use when formatting dates. It
4053   *     can contain any of the formatting options described at
4054   *     http://php.net/manual/en/function.date.php
4055   *   - 'locales': (optional) An array of 2 and 5 character locale codes,
4056   *     defining which locales this format applies to (for example, 'en',
4057   *     'en-us', etc.). If your date format is not language-specific, leave this
4058   *     array empty.
4059   *
4060   * @see hook_date_format_types()
4061   */
4062  function hook_date_formats() {
4063    return array(
4064      array(
4065        'type' => 'mymodule_extra_long',
4066        'format' => 'l jS F Y H:i:s e',
4067        'locales' => array('en-ie'),
4068      ),
4069      array(
4070        'type' => 'mymodule_extra_long',
4071        'format' => 'l jS F Y h:i:sa',
4072        'locales' => array('en', 'en-us'),
4073      ),
4074      array(
4075        'type' => 'short',
4076        'format' => 'F Y',
4077        'locales' => array(),
4078      ),
4079    );
4080  }
4081  
4082  /**
4083   * Alter date formats declared by another module.
4084   *
4085   * Called by _system_date_format_types_build() to allow modules to alter the
4086   * return values from implementations of hook_date_formats().
4087   */
4088  function hook_date_formats_alter(&$formats) {
4089    foreach ($formats as $id => $format) {
4090      $formats[$id]['locales'][] = 'en-ca';
4091    }
4092  }
4093  
4094  /**
4095   * Alters the delivery callback used to send the result of the page callback to the browser.
4096   *
4097   * Called by drupal_deliver_page() to allow modules to alter how the
4098   * page is delivered to the browser.
4099   *
4100   * This hook is intended for altering the delivery callback based on
4101   * information unrelated to the path of the page accessed. For example,
4102   * it can be used to set the delivery callback based on a HTTP request
4103   * header (as shown in the code sample). To specify a delivery callback
4104   * based on path information, use hook_menu() or hook_menu_alter().
4105   *
4106   * This hook can also be used as an API function that can be used to explicitly
4107   * set the delivery callback from some other function. For example, for a module
4108   * named MODULE:
4109   * @code
4110   * function MODULE_page_delivery_callback_alter(&$callback, $set = FALSE) {
4111   *   static $stored_callback;
4112   *   if ($set) {
4113   *     $stored_callback = $callback;
4114   *   }
4115   *   elseif (isset($stored_callback)) {
4116   *     $callback = $stored_callback;
4117   *   }
4118   * }
4119   * function SOMEWHERE_ELSE() {
4120   *   $desired_delivery_callback = 'foo';
4121   *   MODULE_page_delivery_callback_alter($desired_delivery_callback, TRUE);
4122   * }
4123   * @endcode
4124   *
4125   * @param $callback
4126   *   The name of a function.
4127   *
4128   * @see drupal_deliver_page()
4129   */
4130  function hook_page_delivery_callback_alter(&$callback) {
4131    // jQuery sets a HTTP_X_REQUESTED_WITH header of 'XMLHttpRequest'.
4132    // If a page would normally be delivered as an html page, and it is called
4133    // from jQuery, deliver it instead as an Ajax response.
4134    if (isset($_SERVER['HTTP_X_REQUESTED_WITH']) && $_SERVER['HTTP_X_REQUESTED_WITH'] == 'XMLHttpRequest' && $callback == 'drupal_deliver_html_page') {
4135      $callback = 'ajax_deliver';
4136    }
4137  }
4138  
4139  /**
4140   * Alters theme operation links.
4141   *
4142   * @param $theme_groups
4143   *   An associative array containing groups of themes.
4144   *
4145   * @see system_themes_page()
4146   */
4147  function hook_system_themes_page_alter(&$theme_groups) {
4148    foreach ($theme_groups as $state => &$group) {
4149      foreach ($theme_groups[$state] as &$theme) {
4150        // Add a foo link to each list of theme operations.
4151        $theme->operations[] = array(
4152          'title' => t('Foo'),
4153          'href' => 'admin/appearance/foo',
4154          'query' => array('theme' => $theme->name)
4155        );
4156      }
4157    }
4158  }
4159  
4160  /**
4161   * Alters inbound URL requests.
4162   *
4163   * @param $path
4164   *   The path being constructed, which, if a path alias, has been resolved to a
4165   *   Drupal path by the database, and which also may have been altered by other
4166   *   modules before this one.
4167   * @param $original_path
4168   *   The original path, before being checked for path aliases or altered by any
4169   *   modules.
4170   * @param $path_language
4171   *   The language of the path.
4172   *
4173   * @see drupal_get_normal_path()
4174   */
4175  function hook_url_inbound_alter(&$path, $original_path, $path_language) {
4176    // Create the path user/me/edit, which allows a user to edit their account.
4177    if (preg_match('|^user/me/edit(/.*)?|', $path, $matches)) {
4178      global $user;
4179      $path = 'user/' . $user->uid . '/edit' . $matches[1];
4180    }
4181  }
4182  
4183  /**
4184   * Alters outbound URLs.
4185   *
4186   * @param $path
4187   *   The outbound path to alter, not adjusted for path aliases yet. It won't be
4188   *   adjusted for path aliases until all modules are finished altering it, thus
4189   *   being consistent with hook_url_inbound_alter(), which adjusts for all path
4190   *   aliases before allowing modules to alter it. This may have been altered by
4191   *   other modules before this one.
4192   * @param $options
4193   *   A set of URL options for the URL so elements such as a fragment or a query
4194   *   string can be added to the URL.
4195   * @param $original_path
4196   *   The original path, before being altered by any modules.
4197   *
4198   * @see url()
4199   */
4200  function hook_url_outbound_alter(&$path, &$options, $original_path) {
4201    // Use an external RSS feed rather than the Drupal one.
4202    if ($path == 'rss.xml') {
4203      $path = 'http://example.com/rss.xml';
4204      $options['external'] = TRUE;
4205    }
4206  
4207    // Instead of pointing to user/[uid]/edit, point to user/me/edit.
4208    if (preg_match('|^user/([0-9]*)/edit(/.*)?|', $path, $matches)) {
4209      global $user;
4210      if ($user->uid == $matches[1]) {
4211        $path = 'user/me/edit' . $matches[2];
4212      }
4213    }
4214  }
4215  
4216  /**
4217   * Alter the username that is displayed for a user.
4218   *
4219   * Called by format_username() to allow modules to alter the username that's
4220   * displayed. Can be used to ensure user privacy in situations where
4221   * $account->name is too revealing.
4222   *
4223   * @param $name
4224   *   The string that format_username() will return.
4225   *
4226   * @param $account
4227   *   The account object passed to format_username().
4228   *
4229   * @see format_username()
4230   */
4231  function hook_username_alter(&$name, $account) {
4232    // Display the user's uid instead of name.
4233    if (isset($account->uid)) {
4234      $name = t('User !uid', array('!uid' => $account->uid));
4235    }
4236  }
4237  
4238  /**
4239   * Provide replacement values for placeholder tokens.
4240   *
4241   * This hook is invoked when someone calls token_replace(). That function first
4242   * scans the text for [type:token] patterns, and splits the needed tokens into
4243   * groups by type. Then hook_tokens() is invoked on each token-type group,
4244   * allowing your module to respond by providing replacement text for any of
4245   * the tokens in the group that your module knows how to process.
4246   *
4247   * A module implementing this hook should also implement hook_token_info() in
4248   * order to list its available tokens on editing screens.
4249   *
4250   * @param $type
4251   *   The machine-readable name of the type (group) of token being replaced, such
4252   *   as 'node', 'user', or another type defined by a hook_token_info()
4253   *   implementation.
4254   * @param $tokens
4255   *   An array of tokens to be replaced. The keys are the machine-readable token
4256   *   names, and the values are the raw [type:token] strings that appeared in the
4257   *   original text.
4258   * @param $data
4259   *   (optional) An associative array of data objects to be used when generating
4260   *   replacement values, as supplied in the $data parameter to token_replace().
4261   * @param $options
4262   *   (optional) An associative array of options for token replacement; see
4263   *   token_replace() for possible values.
4264   *
4265   * @return
4266   *   An associative array of replacement values, keyed by the raw [type:token]
4267   *   strings from the original text.
4268   *
4269   * @see hook_token_info()
4270   * @see hook_tokens_alter()
4271   */
4272  function hook_tokens($type, $tokens, array $data = array(), array $options = array()) {
4273    $url_options = array('absolute' => TRUE);
4274    if (isset($options['language'])) {
4275      $url_options['language'] = $options['language'];
4276      $language_code = $options['language']->language;
4277    }
4278    else {
4279      $language_code = NULL;
4280    }
4281    $sanitize = !empty($options['sanitize']);
4282  
4283    $replacements = array();
4284  
4285    if ($type == 'node' && !empty($data['node'])) {
4286      $node = $data['node'];
4287  
4288      foreach ($tokens as $name => $original) {
4289        switch ($name) {
4290          // Simple key values on the node.
4291          case 'nid':
4292            $replacements[$original] = $node->nid;
4293            break;
4294  
4295          case 'title':
4296            $replacements[$original] = $sanitize ? check_plain($node->title) : $node->title;
4297            break;
4298  
4299          case 'edit-url':
4300            $replacements[$original] = url('node/' . $node->nid . '/edit', $url_options);
4301            break;
4302  
4303          // Default values for the chained tokens handled below.
4304          case 'author':
4305            $name = ($node->uid == 0) ? variable_get('anonymous', t('Anonymous')) : $node->name;
4306            $replacements[$original] = $sanitize ? filter_xss($name) : $name;
4307            break;
4308  
4309          case 'created':
4310            $replacements[$original] = format_date($node->created, 'medium', '', NULL, $language_code);
4311            break;
4312        }
4313      }
4314  
4315      if ($author_tokens = token_find_with_prefix($tokens, 'author')) {
4316        $author = user_load($node->uid);
4317        $replacements += token_generate('user', $author_tokens, array('user' => $author), $options);
4318      }
4319  
4320      if ($created_tokens = token_find_with_prefix($tokens, 'created')) {
4321        $replacements += token_generate('date', $created_tokens, array('date' => $node->created), $options);
4322      }
4323    }
4324  
4325    return $replacements;
4326  }
4327  
4328  /**
4329   * Alter replacement values for placeholder tokens.
4330   *
4331   * @param $replacements
4332   *   An associative array of replacements returned by hook_tokens().
4333   * @param $context
4334   *   The context in which hook_tokens() was called. An associative array with
4335   *   the following keys, which have the same meaning as the corresponding
4336   *   parameters of hook_tokens():
4337   *   - 'type'
4338   *   - 'tokens'
4339   *   - 'data'
4340   *   - 'options'
4341   *
4342   * @see hook_tokens()
4343   */
4344  function hook_tokens_alter(array &$replacements, array $context) {
4345    $options = $context['options'];
4346  
4347    if (isset($options['language'])) {
4348      $url_options['language'] = $options['language'];
4349      $language_code = $options['language']->language;
4350    }
4351    else {
4352      $language_code = NULL;
4353    }
4354    $sanitize = !empty($options['sanitize']);
4355  
4356    if ($context['type'] == 'node' && !empty($context['data']['node'])) {
4357      $node = $context['data']['node'];
4358  
4359      // Alter the [node:title] token, and replace it with the rendered content
4360      // of a field (field_title).
4361      if (isset($context['tokens']['title'])) {
4362        $title = field_view_field('node', $node, 'field_title', 'default', $language_code);
4363        $replacements[$context['tokens']['title']] = drupal_render($title);
4364      }
4365    }
4366  }
4367  
4368  /**
4369   * Provide information about available placeholder tokens and token types.
4370   *
4371   * Tokens are placeholders that can be put into text by using the syntax
4372   * [type:token], where type is the machine-readable name of a token type, and
4373   * token is the machine-readable name of a token within this group. This hook
4374   * provides a list of types and tokens to be displayed on text editing screens,
4375   * so that people editing text can see what their token options are.
4376   *
4377   * The actual token replacement is done by token_replace(), which invokes
4378   * hook_tokens(). Your module will need to implement that hook in order to
4379   * generate token replacements from the tokens defined here.
4380   *
4381   * @return
4382   *   An associative array of available tokens and token types. The outer array
4383   *   has two components:
4384   *   - types: An associative array of token types (groups). Each token type is
4385   *     an associative array with the following components:
4386   *     - name: The translated human-readable short name of the token type.
4387   *     - description: A translated longer description of the token type.
4388   *     - needs-data: The type of data that must be provided to token_replace()
4389   *       in the $data argument (i.e., the key name in $data) in order for tokens
4390   *       of this type to be used in the $text being processed. For instance, if
4391   *       the token needs a node object, 'needs-data' should be 'node', and to
4392   *       use this token in token_replace(), the caller needs to supply a node
4393   *       object as $data['node']. Some token data can also be supplied
4394   *       indirectly; for instance, a node object in $data supplies a user object
4395   *       (the author of the node), allowing user tokens to be used when only
4396   *       a node data object is supplied.
4397   *   - tokens: An associative array of tokens. The outer array is keyed by the
4398   *     group name (the same key as in the types array). Within each group of
4399   *     tokens, each token item is keyed by the machine name of the token, and
4400   *     each token item has the following components:
4401   *     - name: The translated human-readable short name of the token.
4402   *     - description: A translated longer description of the token.
4403   *     - type (optional): A 'needs-data' data type supplied by this token, which
4404   *       should match a 'needs-data' value from another token type. For example,
4405   *       the node author token provides a user object, which can then be used
4406   *       for token replacement data in token_replace() without having to supply
4407   *       a separate user object.
4408   *
4409   * @see hook_token_info_alter()
4410   * @see hook_tokens()
4411   */
4412  function hook_token_info() {
4413    $type = array(
4414      'name' => t('Nodes'),
4415      'description' => t('Tokens related to individual nodes.'),
4416      'needs-data' => 'node',
4417    );
4418  
4419    // Core tokens for nodes.
4420    $node['nid'] = array(
4421      'name' => t("Node ID"),
4422      'description' => t("The unique ID of the node."),
4423    );
4424    $node['title'] = array(
4425      'name' => t("Title"),
4426      'description' => t("The title of the node."),
4427    );
4428    $node['edit-url'] = array(
4429      'name' => t("Edit URL"),
4430      'description' => t("The URL of the node's edit page."),
4431    );
4432  
4433    // Chained tokens for nodes.
4434    $node['created'] = array(
4435      'name' => t("Date created"),
4436      'description' => t("The date the node was posted."),
4437      'type' => 'date',
4438    );
4439    $node['author'] = array(
4440      'name' => t("Author"),
4441      'description' => t("The author of the node."),
4442      'type' => 'user',
4443    );
4444  
4445    return array(
4446      'types' => array('node' => $type),
4447      'tokens' => array('node' => $node),
4448    );
4449  }
4450  
4451  /**
4452   * Alter the metadata about available placeholder tokens and token types.
4453   *
4454   * @param $data
4455   *   The associative array of token definitions from hook_token_info().
4456   *
4457   * @see hook_token_info()
4458   */
4459  function hook_token_info_alter(&$data) {
4460    // Modify description of node tokens for our site.
4461    $data['tokens']['node']['nid'] = array(
4462      'name' => t("Node ID"),
4463      'description' => t("The unique ID of the article."),
4464    );
4465    $data['tokens']['node']['title'] = array(
4466      'name' => t("Title"),
4467      'description' => t("The title of the article."),
4468    );
4469  
4470    // Chained tokens for nodes.
4471    $data['tokens']['node']['created'] = array(
4472      'name' => t("Date created"),
4473      'description' => t("The date the article was posted."),
4474      'type' => 'date',
4475    );
4476  }
4477  
4478  /**
4479   * Alter batch information before a batch is processed.
4480   *
4481   * Called by batch_process() to allow modules to alter a batch before it is
4482   * processed.
4483   *
4484   * @param $batch
4485   *   The associative array of batch information. See batch_set() for details on
4486   *   what this could contain.
4487   *
4488   * @see batch_set()
4489   * @see batch_process()
4490   *
4491   * @ingroup batch
4492   */
4493  function hook_batch_alter(&$batch) {
4494    // If the current page request is inside the overlay, add ?render=overlay to
4495    // the success callback URL, so that it appears correctly within the overlay.
4496    if (overlay_get_mode() == 'child') {
4497      if (isset($batch['url_options']['query'])) {
4498        $batch['url_options']['query']['render'] = 'overlay';
4499      }
4500      else {
4501        $batch['url_options']['query'] = array('render' => 'overlay');
4502      }
4503    }
4504  }
4505  
4506  /**
4507   * Provide information on Updaters (classes that can update Drupal).
4508   *
4509   * An Updater is a class that knows how to update various parts of the Drupal
4510   * file system, for example to update modules that have newer releases, or to
4511   * install a new theme.
4512   *
4513   * @return
4514   *   An associative array of information about the updater(s) being provided.
4515   *   This array is keyed by a unique identifier for each updater, and the
4516   *   values are subarrays that can contain the following keys:
4517   *   - class: The name of the PHP class which implements this updater.
4518   *   - name: Human-readable name of this updater.
4519   *   - weight: Controls what order the Updater classes are consulted to decide
4520   *     which one should handle a given task. When an update task is being run,
4521   *     the system will loop through all the Updater classes defined in this
4522   *     registry in weight order and let each class respond to the task and
4523   *     decide if each Updater wants to handle the task. In general, this
4524   *     doesn't matter, but if you need to override an existing Updater, make
4525   *     sure your Updater has a lighter weight so that it comes first.
4526   *
4527   * @see drupal_get_updaters()
4528   * @see hook_updater_info_alter()
4529   */
4530  function hook_updater_info() {
4531    return array(
4532      'module' => array(
4533        'class' => 'ModuleUpdater',
4534        'name' => t('Update modules'),
4535        'weight' => 0,
4536      ),
4537      'theme' => array(
4538        'class' => 'ThemeUpdater',
4539        'name' => t('Update themes'),
4540        'weight' => 0,
4541      ),
4542    );
4543  }
4544  
4545  /**
4546   * Alter the Updater information array.
4547   *
4548   * An Updater is a class that knows how to update various parts of the Drupal
4549   * file system, for example to update modules that have newer releases, or to
4550   * install a new theme.
4551   *
4552   * @param array $updaters
4553   *   Associative array of updaters as defined through hook_updater_info().
4554   *   Alter this array directly.
4555   *
4556   * @see drupal_get_updaters()
4557   * @see hook_updater_info()
4558   */
4559  function hook_updater_info_alter(&$updaters) {
4560    // Adjust weight so that the theme Updater gets a chance to handle a given
4561    // update task before module updaters.
4562    $updaters['theme']['weight'] = -1;
4563  }
4564  
4565  /**
4566   * Alter the default country list.
4567   *
4568   * @param $countries
4569   *   The associative array of countries keyed by ISO 3166-1 country code.
4570   *
4571   * @see country_get_list()
4572   * @see _country_get_predefined_list()
4573   */
4574  function hook_countries_alter(&$countries) {
4575    // Elbonia is now independent, so add it to the country list.
4576    $countries['EB'] = 'Elbonia';
4577  }
4578  
4579  /**
4580   * Control site status before menu dispatching.
4581   *
4582   * The hook is called after checking whether the site is offline but before
4583   * the current router item is retrieved and executed by
4584   * menu_execute_active_handler(). If the site is in offline mode,
4585   * $menu_site_status is set to MENU_SITE_OFFLINE.
4586   *
4587   * @param $menu_site_status
4588   *   Supported values are MENU_SITE_OFFLINE, MENU_ACCESS_DENIED,
4589   *   MENU_NOT_FOUND and MENU_SITE_ONLINE. Any other value than
4590   *   MENU_SITE_ONLINE will skip the default menu handling system and be passed
4591   *   for delivery to drupal_deliver_page() with a NULL
4592   *   $default_delivery_callback.
4593   * @param $path
4594   *   Contains the system path that is going to be loaded. This is read only,
4595   *   use hook_url_inbound_alter() to change the path.
4596   */
4597  function hook_menu_site_status_alter(&$menu_site_status, $path) {
4598    // Allow access to my_module/authentication even if site is in offline mode.
4599    if ($menu_site_status == MENU_SITE_OFFLINE && user_is_anonymous() && $path == 'my_module/authentication') {
4600      $menu_site_status = MENU_SITE_ONLINE;
4601    }
4602  }
4603  
4604  /**
4605   * Register information about FileTransfer classes provided by a module.
4606   *
4607   * The FileTransfer class allows transferring files over a specific type of
4608   * connection. Core provides classes for FTP and SSH. Contributed modules are
4609   * free to extend the FileTransfer base class to add other connection types,
4610   * and if these classes are registered via hook_filetransfer_info(), those
4611   * connection types will be available to site administrators using the Update
4612   * manager when they are redirected to the authorize.php script to authorize
4613   * the file operations.
4614   *
4615   * @return array
4616   *   Nested array of information about FileTransfer classes. Each key is a
4617   *   FileTransfer type (not human readable, used for form elements and
4618   *   variable names, etc), and the values are subarrays that define properties
4619   *   of that type. The keys in each subarray are:
4620   *   - 'title': Required. The human-readable name of the connection type.
4621   *   - 'class': Required. The name of the FileTransfer class. The constructor
4622   *     will always be passed the full path to the root of the site that should
4623   *     be used to restrict where file transfer operations can occur (the $jail)
4624   *     and an array of settings values returned by the settings form.
4625   *   - 'file': Required. The include file containing the FileTransfer class.
4626   *     This should be a separate .inc file, not just the .module file, so that
4627   *     the minimum possible code is loaded when authorize.php is running.
4628   *   - 'file path': Optional. The directory (relative to the Drupal root)
4629   *     where the include file lives. If not defined, defaults to the base
4630   *     directory of the module implementing the hook.
4631   *   - 'weight': Optional. Integer weight used for sorting connection types on
4632   *     the authorize.php form.
4633   *
4634   * @see FileTransfer
4635   * @see authorize.php
4636   * @see hook_filetransfer_info_alter()
4637   * @see drupal_get_filetransfer_info()
4638   */
4639  function hook_filetransfer_info() {
4640    $info['sftp'] = array(
4641      'title' => t('SFTP (Secure FTP)'),
4642      'file' => 'sftp.filetransfer.inc',
4643      'class' => 'FileTransferSFTP',
4644      'weight' => 10,
4645    );
4646    return $info;
4647  }
4648  
4649  /**
4650   * Alter the FileTransfer class registry.
4651   *
4652   * @param array $filetransfer_info
4653   *   Reference to a nested array containing information about the FileTransfer
4654   *   class registry.
4655   *
4656   * @see hook_filetransfer_info()
4657   */
4658  function hook_filetransfer_info_alter(&$filetransfer_info) {
4659    if (variable_get('paranoia', FALSE)) {
4660      // Remove the FTP option entirely.
4661      unset($filetransfer_info['ftp']);
4662      // Make sure the SSH option is listed first.
4663      $filetransfer_info['ssh']['weight'] = -10;
4664    }
4665  }
4666  
4667  /**
4668   * @} End of "addtogroup hooks".
4669   */
4670  
4671  /**
4672   * @defgroup update_api Update versions of API functions
4673   * @{
4674   * Functions that are similar to normal API functions, but do not invoke hooks.
4675   *
4676   * These simplified versions of core API functions are provided for use by
4677   * update functions (hook_update_N() implementations).
4678   *
4679   * During database updates the schema of any module could be out of date. For
4680   * this reason, caution is needed when using any API function within an update
4681   * function - particularly CRUD functions, functions that depend on the schema
4682   * (for example by using drupal_write_record()), and any functions that invoke
4683   * hooks.
4684   *
4685   * Instead, a simplified utility function should be used. If a utility version
4686   * of the API function you require does not already exist, then you should
4687   * create a new function. The new utility function should be named
4688   * _update_N_mymodule_my_function(). N is the schema version the function acts
4689   * on (the schema version is the number N from the hook_update_N()
4690   * implementation where this schema was introduced, or a number following the
4691   * same numbering scheme), and mymodule_my_function is the name of the original
4692   * API function including the module's name.
4693   *
4694   * Examples:
4695   * - _update_6000_mymodule_save(): This function performs a save operation
4696   *   without invoking any hooks using the 6.x schema.
4697   * - _update_7000_mymodule_save(): This function performs the same save
4698   *   operation using the 7.x schema.
4699   *
4700   * The utility function should not invoke any hooks, and should perform database
4701   * operations using functions from the
4702   * @link database Database abstraction layer, @endlink
4703   * like db_insert(), db_update(), db_delete(), db_query(), and so on.
4704   *
4705   * If a change to the schema necessitates a change to the utility function, a
4706   * new function should be created with a name based on the version of the schema
4707   * it acts on. See _update_7000_bar_get_types() and _update_7001_bar_get_types()
4708   * in the code examples that follow.
4709   *
4710   * For example, foo.install could contain:
4711   * @code
4712   * function foo_update_dependencies() {
4713   *   // foo_update_7010() needs to run after bar_update_7000().
4714   *   $dependencies['foo'][7010] = array(
4715   *     'bar' => 7000,
4716   *   );
4717   *
4718   *   // foo_update_7036() needs to run after bar_update_7001().
4719   *   $dependencies['foo'][7036] = array(
4720   *     'bar' => 7001,
4721   *   );
4722   *
4723   *   return $dependencies;
4724   * }
4725   *
4726   * function foo_update_7000() {
4727   *   // No updates have been run on the {bar_types} table yet, so this needs
4728   *   // to work with the 6.x schema.
4729   *   foreach (_update_6000_bar_get_types() as $type) {
4730   *     // Rename a variable.
4731   *   }
4732   * }
4733   *
4734   * function foo_update_7010() {
4735   *    // Since foo_update_7010() is going to run after bar_update_7000(), it
4736   *    // needs to operate on the new schema, not the old one.
4737   *    foreach (_update_7000_bar_get_types() as $type) {
4738   *      // Rename a different variable.
4739   *    }
4740   * }
4741   *
4742   * function foo_update_7036() {
4743   *   // This update will run after bar_update_7001().
4744   *   foreach (_update_7001_bar_get_types() as $type) {
4745   *   }
4746   * }
4747   * @endcode
4748   *
4749   * And bar.install could contain:
4750   * @code
4751   * function bar_update_7000() {
4752   *   // Type and bundle are confusing, so we renamed the table.
4753   *   db_rename_table('bar_types', 'bar_bundles');
4754   * }
4755   *
4756   * function bar_update_7001() {
4757   *   // Database table names should be singular when possible.
4758   *   db_rename_table('bar_bundles', 'bar_bundle');
4759   * }
4760   *
4761   * function _update_6000_bar_get_types() {
4762   *   db_query('SELECT * FROM {bar_types}')->fetchAll();
4763   * }
4764   *
4765   * function _update_7000_bar_get_types() {
4766   *   db_query('SELECT * FROM {bar_bundles'})->fetchAll();
4767   * }
4768   *
4769   * function _update_7001_bar_get_types() {
4770   *   db_query('SELECT * FROM {bar_bundle}')->fetchAll();
4771   * }
4772   * @endcode
4773   *
4774   * @see hook_update_N()
4775   * @see hook_update_dependencies()
4776   */
4777  
4778  /**
4779   * @} End of "defgroup update_api".
4780   */

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