system.api.php 60.5 KB
Newer Older
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
<?php
// $Id$

/**
 * @file
 * Hooks provided by Drupal core and the System module.
 */

/**
 * @addtogroup hooks
 * @{
 */

/**
 * Perform periodic actions.
 *
 * Modules that require to schedule some commands to be executed at regular
 * intervals can implement hook_cron(). The engine will then call the hook
 * at the appropriate intervals defined by the administrator. This interface
 * is particularly handy to implement timers or to automate certain tasks.
 * Database maintenance, recalculation of settings or parameters, and
 * automatic mailings are good candidates for cron tasks.
 *
 * @return
 *   None.
 *
 * This hook will only be called if cron.php is run (e.g. by crontab).
 */
function hook_cron() {
  $result = db_query('SELECT * FROM {site} WHERE checked = 0 OR checked + refresh < :time', array(':time' => REQUEST_TIME));

  foreach ($result as $site) {
    cloud_update($site);
  }
}

/**
 * Rewrite database queries, usually for access control.
 *
 * Add JOIN and WHERE statements to queries and decide whether the primary_field
 * shall be made DISTINCT. For node objects, primary field is always called nid.
 * For taxonomy terms, it is tid and for vocabularies it is vid. For comments,
 * it is cid. Primary table is the table where the primary object (node, file,
44
 * taxonomy_term_node etc.) is.
45
46
47
48
49
50
51
52
53
 *
 * You shall return an associative array. Possible keys are 'join', 'where' and
 * 'distinct'. The value of 'distinct' shall be 1 if you want that the
 * primary_field made DISTINCT.
 *
 * @param $query
 *   Query to be rewritten.
 * @param $primary_table
 *   Name or alias of the table which has the primary key field for this query.
54
 *   Typical table names would be: {block}, {comment}, {forum}, {node},
55
 *   {menu}, {taxonomy_term_data} or {taxonomy_vocabulary}. However, it is more common for
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
 *   $primary_table to contain the usual table alias: b, c, f, n, m, t or v.
 * @param $primary_field
 *   Name of the primary field.
 * @param $args
 *   Array of additional arguments.
 * @return
 *   An array of join statements, where statements, distinct decision.
 */
function hook_db_rewrite_sql($query, $primary_table, $primary_field, $args) {
  switch ($primary_field) {
    case 'nid':
      // this query deals with node objects
      $return = array();
      if ($primary_table != 'n') {
        $return['join'] = "LEFT JOIN {node} n ON $primary_table.nid = n.nid";
      }
      $return['where'] = 'created >' . mktime(0, 0, 0, 1, 1, 2005);
      return $return;
      break;
    case 'tid':
      // this query deals with taxonomy objects
      break;
    case 'vid':
      // this query deals with vocabulary objects
      break;
  }
}

/**
 * Allows modules to declare their own Forms API element types and specify their
 * default values.
 *
 * This hook allows modules to declare their own form element types and to
 * specify their default values. The values returned by this hook will be
 * merged with the elements returned by hook_form() implementations and so
 * can return defaults for any Form APIs keys in addition to those explicitly
 * mentioned below.
 *
 * Each of the form element types defined by this hook is assumed to have
 * a matching theme function, e.g. theme_elementtype(), which should be
 * registered with hook_theme() as normal.
 *
 * Form more information about custom element types see the explanation at
 * http://drupal.org/node/169815.
 *
 * @return
 *  An associative array describing the element types being defined. The array
 *  contains a sub-array for each element type, with the machine-readable type
 *  name as the key. Each sub-array has a number of possible attributes:
 *  - "#input": boolean indicating whether or not this element carries a value
 *    (even if it's hidden).
 *  - "#process": array of callback functions taking $element and $form_state.
 *  - "#after_build": array of callback functions taking $element and $form_state.
 *  - "#validate": array of callback functions taking $form and $form_state.
 *  - "#element_validate": array of callback functions taking $element and
 *    $form_state.
 *  - "#pre_render": array of callback functions taking $element and $form_state.
 *  - "#post_render": array of callback functions taking $element and $form_state.
 *  - "#submit": array of callback functions taking $form and $form_state.
 */
function hook_elements() {
  $type['filter_format'] = array('#input' => TRUE);
  return $type;
}

/**
 * Perform cleanup tasks.
 *
 * This hook is run at the end of each page request. It is often used for
 * page logging and printing out debugging information.
 *
 * Only use this hook if your code must run even for cached page views.
 * If you have code which must run once on all non cached pages, use
 * hook_init instead. Thats the usual case. If you implement this hook
 * and see an error like 'Call to undefined function', it is likely that
 * you are depending on the presence of a module which has not been loaded yet.
 * It is not loaded because Drupal is still in bootstrap mode.
 *
 * @param $destination
 *   If this hook is invoked as part of a drupal_goto() call, then this argument
 *   will be a fully-qualified URL that is the destination of the redirect.
 *   Modules may use this to react appropriately; for example, nothing should
 *   be output in this case, because PHP will then throw a "headers cannot be
 *   modified" error when attempting the redirection.
 * @return
 *   None.
 */
function hook_exit($destination = NULL) {
  db_query('UPDATE {counter} SET hits = hits + 1 WHERE type = 1');
}

/**
 * Insert closing HTML.
 *
 * This hook enables modules to insert HTML just before the \</body\> closing
 * tag of web pages. This is useful for adding JavaScript code to the footer
 * and for outputting debug information. It is not possible to add JavaScript
 * to the header at this point, and developers wishing to do so should use
 * hook_init() instead.
 *
 * @param $main
 *   Whether the current page is the front page of the site.
 * @return
 *   The HTML to be inserted.
 */
function hook_footer($main = 0) {
  if (variable_get('dev_query', 0)) {
    return '<div style="clear:both;">' . devel_query_table() . '</div>';
  }
}

/**
 * Perform necessary alterations to the JavaScript before it is presented on
 * the page.
 *
 * @param $javascript
 *   An array of all JavaScript being presented on the page.
 * @see drupal_add_js()
 * @see drupal_get_js()
 * @see drupal_js_defaults()
 */
function hook_js_alter(&$javascript) {
  // Swap out jQuery to use an updated version of the library.
  $javascript['misc/jquery.js']['data'] = drupal_get_path('module', 'jquery_update') . '/jquery.js';
}

182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
/**
 * Perform alterations before a page is rendered.
 *
 * Use this hook when you want to add, remove, or alter elements at the page
 * level. If you are making changes to entities such as forms, menus, or user
 * profiles, use those objects' native alter hooks instead (hook_form_alter(),
 * for example).
 *
 * The $page array contains top level elements for each block region:
 * @code
 *   $page['header']
 *   $page['left']
 *   $page['content']
 *   $page['right']
 *   $page['footer']
 * @endcode
 *
 * The 'content' element contains the main content of the current page, and its
 * structure will vary depending on what module is responsible for building the
 * page. Some legacy modules may not return structured content at all: their
 * pre-rendered markup will be located in $page['content']['main']['#markup'].
 *
 * Pages built by Drupal's core Node and Blog modules use a standard structure:
 *
 * @code
 *   // Node body.
 *   $page['content']['nodes'][$nid]['body']
 *   // Array of links attached to the node (add comments, read more).
 *   $page['content']['nodes'][$nid]['links']
 *   // The node object itself.
 *   $page['content']['nodes'][$nid]['#node']
 *   // The results pager.
 *   $page['content']['pager']
215
 * @endcode
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
 *
 * Blocks may be referenced by their module/delta pair within a region:
 * @code
 *   // The login block in the left sidebar region.
 *   $page['left']['user-login']['#block'];
 * @endcode
 *
 * @param $page
 *   Nested array of renderable elements that make up the page.
 *
 * @see drupal_render_page()
 */
function hook_page_alter($page) {
  if (menu_get_object('node', 1)) {
    // We are on a node detail page. Append a standard disclaimer to the
    // content region.
    $page['content']['disclaimer'] = array(
      '#markup' => t('Acme, Inc. is not responsible for the contents of this sample code.'),
      '#weight' => 25,
    );
  }
}

239
240
241
242
243
244
/**
 * Perform alterations before a form is rendered.
 *
 * One popular use of this hook is to add form elements to the node form. When
 * altering a node form, the node object retrieved at from $form['#node'].
 *
245
246
247
 * Note that you can also use hook_FORM_ID_alter() to alter a specific form,
 * instead of this hook, which gets called for all forms.
 *
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
 * @param $form
 *   Nested array of form elements that comprise the form.
 * @param $form_state
 *   A keyed array containing the current state of the form.
 * @param $form_id
 *   String representing the name of the form itself. Typically this is the
 *   name of the function that generated the form.
 * @return
 *   None.
 */
function hook_form_alter(&$form, $form_state, $form_id) {
  if (isset($form['type']) && $form['type']['#value'] . '_node_settings' == $form_id) {
    $form['workflow']['upload_' . $form['type']['#value']] = array(
      '#type' => 'radios',
      '#title' => t('Attachments'),
      '#default_value' => variable_get('upload_' . $form['type']['#value'], 1),
      '#options' => array(t('Disabled'), t('Enabled')),
    );
  }
}

/**
 * Provide a form-specific alteration instead of the global hook_form_alter().
 *
 * Modules can implement hook_form_FORM_ID_alter() to modify a specific form,
 * rather than implementing hook_form_alter() and checking the form ID, or
 * using long switch statements to alter multiple forms.
 *
 * Note that this hook fires before hook_form_alter(). Therefore all
 * implementations of hook_form_FORM_ID_alter() will run before all implementations
 * of hook_form_alter(), regardless of the module order.
 *
 * @param $form
 *   Nested array of form elements that comprise the form.
 * @param $form_state
 *   A keyed array containing the current state of the form.
 * @return
 *   None.
 *
 * @see drupal_prepare_form().
 */
function hook_form_FORM_ID_alter(&$form, &$form_state) {
  // Modification for the form with the given form ID goes here. For example, if
  // FORM_ID is "user_register" this code would run only on the user
  // registration form.

  // Add a checkbox to registration form about agreeing to terms of use.
  $form['terms_of_use'] = array(
    '#type' => 'checkbox',
    '#title' => t("I agree with the website's terms and conditions."),
    '#required' => TRUE,
  );
}

/**
 * Map form_ids to builder functions.
 *
 * This hook allows modules to build multiple forms from a single form "factory"
 * function but each form will have a different form id for submission,
 * validation, theming or alteration by other modules.
 *
 * The callback arguments will be passed as parameters to the function. Callers
 * of drupal_get_form() are also able to pass in parameters. These will be
 * appended after those specified by hook_forms().
 *
 * See node_forms() for an actual example of how multiple forms share a common
 * building function.
 *
 * @return
 *   An array keyed by form id with callbacks and optional, callback arguments.
 */
function hook_forms() {
  $forms['mymodule_first_form'] = array(
    'callback' => 'mymodule_form_builder',
    'callback arguments' => array('some parameter'),
  );
  $forms['mymodule_second_form'] = array(
    'callback' => 'mymodule_form_builder',
  );
  return $forms;
}

/**
 * Perform setup tasks. See also, hook_init.
 *
 * This hook is run at the beginning of the page request. It is typically
 * used to set up global parameters which are needed later in the request.
 *
 * Only use this hook if your code must run even for cached page views.This hook
 * is called before modules or most include files are loaded into memory.
 * It happens while Drupal is still in bootstrap mode.
 *
 * @return
 *   None.
 */
function hook_boot() {
  // we need user_access() in the shutdown function. make sure it gets loaded
  drupal_load('module', 'user');
  register_shutdown_function('devel_shutdown');
}

/**
 * Perform setup tasks. See also, hook_boot.
 *
 * This hook is run at the beginning of the page request. It is typically
 * used to set up global parameters which are needed later in the request.
 * when this hook is called, all modules are already loaded in memory.
 *
 * For example, this hook is a typical place for modules to add CSS or JS
 * that should be present on every page. This hook is not run on cached
 * pages - though CSS or JS added this way will be present on a cached page.
 *
 * @return
 *   None.
 */
function hook_init() {
  drupal_add_css(drupal_get_path('module', 'book') . '/book.css');
}

/**
368
369
370
371
372
373
374
375
376
377
378
379
 * Define image toolkits provided by this module.
 *
 * The file which includes each toolkit's functions must be declared as part of
 * the files array in the module .info file so that the registry will find and
 * parse it.
 *
 * The toolkit's functions must be named image_toolkitname_operation().
 * where the operation may be:
 *   - 'load': Required. See image_gd_load() for usage.
 *   - 'save': Required. See image_gd_save() for usage.
 *   - 'settings': Optional. See image_gd_settings() for usage.
 *   - 'resize': Optional. See image_gd_resize() for usage.
380
 *   - 'rotate': Optional. See image_gd_rotate() for usage.
381
382
383
384
385
386
387
388
389
390
391
 *   - 'crop': Optional. See image_gd_crop() for usage.
 *   - 'desaturate': Optional. See image_gd_desaturate() for usage.
 *
 * @return
 *   An array with the toolkit name as keys and sub-arrays with these keys:
 *     - 'title': A string with the toolkit's title.
 *     - 'available': A Boolean value to indicate that the toolkit is operating
 *       properly, e.g. all required libraries exist.
 *
 * @see system_image_toolkits()
 */
392
function hook_image_toolkits() {
393
394
395
396
397
398
399
400
401
402
  return array(
    'working' => array(
      'title' => t('A toolkit that works.'),
      'available' => TRUE,
    ),
    'broken' => array(
      'title' => t('A toolkit that is "broken" and will not be listed.'),
      'available' => FALSE,
    ),
  );
403
404
405
406
407
408
}

/**
 * Define internal Drupal links.
 *
 * This hook enables modules to add links to many parts of Drupal. Links
409
 * may be added in the navigation block, for example.
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
 *
 * The returned array should be a keyed array of link entries. Each link can
 * be in one of two formats.
 *
 * The first format will use the l() function to render the link:
 *   - attributes: Optional. See l() for usage.
 *   - fragment: Optional. See l() for usage.
 *   - href: Required. The URL of the link.
 *   - html: Optional. See l() for usage.
 *   - query: Optional. See l() for usage.
 *   - title: Required. The name of the link.
 *
 * The second format can be used for non-links. Leaving out the href index will
 * select this format:
 *   - title: Required. The text or HTML code to display.
 *   - attributes: Optional. An associative array of HTML attributes to apply to the span tag.
 *   - html: Optional. If not set to true, check_plain() will be run on the title before it is displayed.
 *
 * @param $type
 *   An identifier declaring what kind of link is being requested.
 *   Possible values:
 *   - comment: Links to be placed below a comment being viewed.
 * @param $object
433
 *   A comment object.
434
 * @param $teaser
435
 *   A 0/1 flag depending on whether the node is
436
437
438
439
440
441
442
443
 *   displayed with its teaser or its full form.
 * @return
 *   An array of the requested links.
 *
 */
function hook_link($type, $object, $teaser = FALSE) {
  $links = array();

444
445
446
  if ($type == 'comment') {
    $links = comment_links($object, FALSE);
    return $links;
447
448
449
450
451
452
  }

  return $links;
}

/**
453
454
 * Perform alterations before links on a comment are rendered. One popular use of
 * this hook is to add/delete links from other modules.
455
456
 *
 * @param $links
457
 *   Nested array of links for the node keyed by providing module.
458
 * @param $node
459
 *   A node object that contains the links.
460
461
462
 * @return
 *   None.
 */
463
464
function hook_link_alter(array &$links, $node) {
  foreach ($links as $module => $link) {
465
466
    if (strstr($module, 'taxonomy_term')) {
      // Link back to the forum and not the taxonomy term page
467
      $links[$module]['href'] = str_replace('taxonomy/term', 'forum', $link['href']);
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
    }
  }
}

/**
 * Perform alterations profile items before they are rendered. You may omit/add/re-sort/re-categorize, etc.
 *
 * @param $account
 *   A user object whose profile is being rendered. Profile items
 *   are stored in $account->content.
 * @return
 *   None.
 */
function hook_profile_alter(&$account) {
  foreach ($account->content AS $key => $field) {
    // do something
  }
}

/**
 * Alter any aspect of the emails sent by Drupal. You can use this hook
 * to add a common site footer to all outgoing emails; add extra header
 * fields and/or modify the mails sent out in any way. HTML-izing the
 * outgoing mails is one possibility. See also drupal_mail().
 *
 * @param $message
 *   A structured array containing the message to be altered. Keys in this
 *   array include:
 *   mail_id
 *     An id to identify the mail sent. Look into the module source codes
 *     for possible mail_id values.
 *   to
 *     The mail address or addresses where the message will be send to. The
 *     formatting of this string must comply with RFC 2822.
 *   subject
 *     Subject of the e-mail to be sent. This must not contain any newline
 *     characters, or the mail may not be sent properly.
 *   body
 *     An array of lines containing the message to be sent. Drupal will format
 *     the correct line endings for you.
 *   from
 *     The From, Reply-To, Return-Path and Error-To headers in $headers
 *     are already set to this value (if given).
 *   headers
 *     Associative array containing the headers to add. This is typically
 *     used to add extra headers (From, Cc, and Bcc).
 * @return
 *   None.
 */
function hook_mail_alter(&$message) {
  if ($message['mail_id'] == 'my_message') {
    $message['body'] .= "\n\n--\nMail sent out from " . variable_get('sitename', t('Drupal'));
  }
}

/**
 * Alter the information parsed from module and theme .info files
 *
 * This hook is invoked in  module_rebuild_cache() and in system_theme_data().
 * A module may implement this hook in order to add to or alter the data
 * generated by reading the .info file with drupal_parse_info_file().
 *
 * @param &$info
 *   The .info file contents, passed by reference so that it can be altered.
 * @param $file
 *   Full information about the module or theme, including $file->name, and
 *   $file->filename
 */
function hook_system_info_alter(&$info, $file) {
  // Only fill this in if the .info file does not define a 'datestamp'.
  if (empty($info['datestamp'])) {
    $info['datestamp'] = filemtime($file->filename);
  }
}

/**
 * Define user permissions.
 *
 * This hook can supply permissions that the module defines, so that they
 * can be selected on the user permissions page and used to restrict
 * access to actions the module performs.
 *
 * @return
 *   An array of which permission names are the keys and their corresponding value is a description of the permission
 *
 * The permissions in the array do not need to be wrapped with the function t(),
 * since the string extractor takes care of extracting permission names defined in the perm hook for translation.
 *
 * Permissions are checked using user_access().
 *
 * For a detailed usage example, see page_example.module.
 */
function hook_perm() {
  return array(
    'administer my module' => t('Perform maintenance tasks for my module'),
  );
}

/**
 * Register a module (or theme's) theme implementations.
 *
 * Modules and themes implementing this return an array of arrays. The key
 * to each sub-array is the internal name of the hook, and the array contains
 * info about the hook. Each array may contain the following items:
 *
 * - arguments: (required) An array of arguments that this theme hook uses. This
 *   value allows the theme layer to properly utilize templates. The
 *   array keys represent the name of the variable, and the value will be
 *   used as the default value if not specified to the theme() function.
 *   These arguments must be in the same order that they will be given to
 *   the theme() function.
 * - file: The file the implementation resides in. This file will be included
 *   prior to the theme being rendered, to make sure that the function or
 *   preprocess function (as needed) is actually loaded; this makes it possible
 *   to split theme functions out into separate files quite easily.
 * - path: Override the path of the file to be used. Ordinarily the module or
 *   theme path will be used, but if the file will not be in the default path,
 *   include it here. This path should be relative to the Drupal root
 *   directory.
 * - template: If specified, this theme implementation is a template, and this
 *   is the template file <b>without an extension</b>. Do not put .tpl.php
 *   on this file; that extension will be added automatically by the default
 *   rendering engine (which is PHPTemplate). If 'path', above, is specified,
 *   the template should also be in this path.
 * - function: If specified, this will be the function name to invoke for this
 *   implementation. If neither file nor function is specified, a default
 *   function name will be assumed. For example, if a module registers
 *   the 'node' theme hook, 'theme_node' will be assigned to its function.
 *   If the chameleon theme registers the node hook, it will be assigned
 *   'chameleon_node' as its function.
 * - pattern: A regular expression pattern to be used to allow this theme
 *   implementation to have a dynamic name. The convention is to use __ to
 *   differentiate the dynamic portion of the theme. For example, to allow
 *   forums to be themed individually, the pattern might be: 'forum__'. Then,
 *   when the forum is themed, call: <code>theme(array('forum__' . $tid, 'forum'),
 *   $forum)</code>.
 * - preprocess functions: A list of functions used to preprocess this data.
 *   Ordinarily this won't be used; it's automatically filled in. By default,
 *   for a module this will be filled in as template_preprocess_HOOK. For
 *   a theme this will be filled in as phptemplate_preprocess and
 *   phptemplate_preprocess_HOOK as well as themename_preprocess and
 *   themename_preprocess_HOOK.
 * - override preprocess functions: Set to TRUE when a theme does NOT want the
 *   standard preprocess functions to run. This can be used to give a theme
 *   FULL control over how variables are set. For example, if a theme wants
 *   total control over how certain variables in the page.tpl.php are set,
 *   this can be set to true. Please keep in mind that when this is used
 *   by a theme, that theme becomes responsible for making sure necessary
 *   variables are set.
 * - type: (automatically derived) Where the theme hook is defined:
 *   'module', 'theme_engine', or 'theme'.
 * - theme path: (automatically derived) The directory path of the theme or
 *   module, so that it doesn't need to be looked up.
 * - theme paths: (automatically derived) An array of template suggestions where
 *   .tpl.php files related to this theme hook may be found.
 *
 * The following parameters are all optional.
 *
 * @param $existing
 *   An array of existing implementations that may be used for override
 *   purposes. This is primarily useful for themes that may wish to examine
 *   existing implementations to extract data (such as arguments) so that
 *   it may properly register its own, higher priority implementations.
 * @param $type
 *   What 'type' is being processed. This is primarily useful so that themes
 *   tell if they are the actual theme being called or a parent theme.
 *   May be one of:
 *     - module: A module is being checked for theme implementations.
 *     - base_theme_engine: A theme engine is being checked for a theme which is a parent of the actual theme being used.
 *     - theme_engine: A theme engine is being checked for the actual theme being used.
 *     - base_theme: A base theme is being checked for theme implementations.
 *     - theme: The actual theme in use is being checked.
 * @param $theme
 *   The actual name of theme that is being being checked (mostly only useful for
 *   theme engine).
 * @param $path
 *   The directory path of the theme or module, so that it doesn't need to be
 *   looked up.
 *
 * @return
 *   A keyed array of theme hooks.
 */
function hook_theme($existing, $type, $theme, $path) {
  return array(
    'forum_display' => array(
      'arguments' => array('forums' => NULL, 'topics' => NULL, 'parents' => NULL, 'tid' => NULL, 'sortby' => NULL, 'forum_per_page' => NULL),
    ),
    'forum_list' => array(
      'arguments' => array('forums' => NULL, 'parents' => NULL, 'tid' => NULL),
    ),
    'forum_topic_list' => array(
      'arguments' => array('tid' => NULL, 'topics' => NULL, 'sortby' => NULL, 'forum_per_page' => NULL),
    ),
    'forum_icon' => array(
      'arguments' => array('new_posts' => NULL, 'num_posts' => 0, 'comment_mode' => 0, 'sticky' => 0),
    ),
    'forum_topic_navigation' => array(
      'arguments' => array('node' => NULL),
    ),
  );
}

/**
 * Alter the theme registry information returned from hook_theme().
 *
 * The theme registry stores information about all available theme hooks,
 * including which callback functions those hooks will call when triggered,
 * what template files are exposed by these hooks, and so on.
 *
 * Note that this hook is only executed as the theme cache is re-built.
 * Changes here will not be visible until the next cache clear.
 *
 * The $theme_registry array is keyed by theme hook name, and contains the
 * information returned from hook_theme(), as well as additional properties
 * added by _theme_process_registry().
 *
 * For example:
 * @code
 *  $theme_registry['user_profile'] = array(
 *    'arguments' => array(
 *      'account' => NULL,
 *    ),
 *    'template' => 'modules/user/user-profile',
 *    'file' => 'modules/user/user.pages.inc',
 *    'type' => 'module',
 *    'theme path' => 'modules/user',
 *    'theme paths' => array(
 *      0 => 'modules/user',
 *    ),
 *    'preprocess functions' => array(
 *      0 => 'template_preprocess',
 *      1 => 'template_preprocess_user_profile',
 *     ),
 *   )
 * );
 * @endcode
 *
 * @param $theme_registry
 *   The entire cache of theme registry information, post-processing.
 * @see hook_theme()
 * @see _theme_process_registry()
 */
function hook_theme_registry_alter(&$theme_registry) {
  // Kill the next/previous forum topic navigation links.
  foreach ($theme_registry['forum_topic_navigation']['preprocess functions'] as $key => $value) {
    if ($value = 'template_preprocess_forum_topic_navigation') {
      unset($theme_registry['forum_topic_navigation']['preprocess functions'][$key]);
    }
  }
}

/**
 * Register XML-RPC callbacks.
 *
 * This hook lets a module register callback functions to be called when
 * particular XML-RPC methods are invoked by a client.
 *
 * @return
 *   An array which maps XML-RPC methods to Drupal functions. Each array
 *   element is either a pair of method => function or an array with four
 *   entries:
 *   - The XML-RPC method name (for example, module.function).
 *   - The Drupal callback function (for example, module_function).
 *   - The method signature is an array of XML-RPC types. The first element
 *     of this array is the type of return value and then you should write a
 *     list of the types of the parameters. XML-RPC types are the following
 *     (See the types at http://www.xmlrpc.com/spec):
 *       - "boolean": 0 (false) or 1 (true).
 *       - "double": a floating point number (for example, -12.214).
 *       - "int": a integer number (for example,  -12).
 *       - "array": an array without keys (for example, array(1, 2, 3)).
 *       - "struct": an associative array or an object (for example,
 *          array('one' => 1, 'two' => 2)).
 *       - "date": when you return a date, then you may either return a
 *          timestamp (time(), mktime() etc.) or an ISO8601 timestamp. When
 *          date is specified as an input parameter, then you get an object,
 *          which is described in the function xmlrpc_date
 *       - "base64": a string containing binary data, automatically
 *          encoded/decoded automatically.
 *       - "string": anything else, typically a string.
 *   - A descriptive help string, enclosed in a t() function for translation
 *     purposes.
 *   Both forms are shown in the example.
 */
function hook_xmlrpc() {
  return array(
    'drupal.login' => 'drupal_login',
    array(
      'drupal.site.ping',
      'drupal_directory_ping',
      array('boolean', 'string', 'string', 'string', 'string', 'string'),
      t('Handling ping request'))
  );
}

/**
 * Log an event message
 *
 * This hook allows modules to route log events to custom destinations, such as
 * SMS, Email, pager, syslog, ...etc.
 *
 * @param $log_entry
770
 *   An associative array containing the following keys:
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
 *   - type: The type of message for this entry. For contributed modules, this is
 *     normally the module name. Do not use 'debug', use severity WATCHDOG_DEBUG instead.
 *   - user: The user object for the user who was logged in when the event happened.
 *   - request_uri: The Request URI for the page the event happened in.
 *   - referer: The page that referred the use to the page where the event occurred.
 *   - ip: The IP address where the request for the page came from.
 *   - timestamp: The UNIX timetamp of the date/time the event occurred
 *   - severity: One of the following values as defined in RFC 3164 http://www.faqs.org/rfcs/rfc3164.html
 *     WATCHDOG_EMERG     Emergency: system is unusable
 *     WATCHDOG_ALERT     Alert: action must be taken immediately
 *     WATCHDOG_CRITICAL  Critical: critical conditions
 *     WATCHDOG_ERROR     Error: error conditions
 *     WATCHDOG_WARNING   Warning: warning conditions
 *     WATCHDOG_NOTICE    Notice: normal but significant condition
 *     WATCHDOG_INFO      Informational: informational messages
 *     WATCHDOG_DEBUG     Debug: debug-level messages
 *   - link: an optional link provided by the module that called the watchdog() function.
 *   - message: The text of the message to be logged.
 *
 * @return
 *   None.
 */
793
794
function hook_watchdog(array $log_entry) {
  global $base_url, $language;
795
796
797
798
799
800
801
802
803
804
805
806

  $severity_list = array(
    WATCHDOG_EMERG    => t('Emergency'),
    WATCHDOG_ALERT    => t('Alert'),
    WATCHDOG_CRITICAL => t('Critical'),
    WATCHDOG_ERROR    => t('Error'),
    WATCHDOG_WARNING  => t('Warning'),
    WATCHDOG_NOTICE   => t('Notice'),
    WATCHDOG_INFO     => t('Info'),
    WATCHDOG_DEBUG    => t('Debug'),
  );

807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
  $to = 'someone@example.com';
  $params = array();
  $params['subject'] = t('[@site_name] @severity_desc: Alert from your web site', array(
    '@site_name' => variable_get('site_name', 'Drupal'),
    '@severity_desc' => $severity_list[$log_entry['severity']],
  ));

  $params['message']  = "\nSite:         @base_url";
  $params['message'] .= "\nSeverity:     (@severity) @severity_desc";
  $params['message'] .= "\nTimestamp:    @timestamp";
  $params['message'] .= "\nType:         @type";
  $params['message'] .= "\nIP Address:   @ip";
  $params['message'] .= "\nRequest URI:  @request_uri";
  $params['message'] .= "\nReferrer URI: @referer_uri";
  $params['message'] .= "\nUser:         (@uid) @name";
  $params['message'] .= "\nLink:         @link";
  $params['message'] .= "\nMessage:      \n\n@message";

  $params['message'] = t($params['message'], array(
826
    '@base_url'      => $base_url,
827
828
829
830
831
832
833
834
835
836
837
    '@severity'      => $log_entry['severity'],
    '@severity_desc' => $severity_list[$log_entry['severity']],
    '@timestamp'     => format_date($log_entry['timestamp']),
    '@type'          => $log_entry['type'],
    '@ip'            => $log_entry['ip'],
    '@request_uri'   => $log_entry['request_uri'],
    '@referer_uri'   => $log_entry['referer'],
    '@uid'           => $log_entry['user']->uid,
    '@name'          => $log_entry['user']->name,
    '@link'          => strip_tags($log_entry['link']),
    '@message'       => strip_tags($log_entry['message']),
838
839
  ));

840
  drupal_mail('emaillog', 'entry', $to, $language, $params);
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
}

/**
 * Prepare a message based on parameters. @see drupal_mail for more.
 *
 * @param $key
 *   An identifier of the mail.
 * @param $message
 *  An array to be filled in. Keys in this array include:
 *  - 'mail_id':
 *     An id to identify the mail sent. Look into the module source codes
 *     for possible mail_id values.
 *  - 'to':
 *     The mail address or addresses where the message will be send to. The
 *     formatting of this string must comply with RFC 2822.
 *  - 'subject':
 *     Subject of the e-mail to be sent. This must not contain any newline
 *     characters, or the mail may not be sent properly. Empty string when
 *     the hook is invoked.
 *  - 'body':
 *     An array of lines containing the message to be sent. Drupal will format
 *     the correct line endings for you. Empty array when the hook is invoked.
 *  - 'from':
 *     The From, Reply-To, Return-Path and Error-To headers in $headers
 *     are already set to this value (if given).
 *  - 'headers':
 *     Associative array containing the headers to add. This is typically
 *     used to add extra headers (From, Cc, and Bcc).
 * @param $params
 *   An arbitrary array of parameters set by the caller to drupal_mail.
 */
function hook_mail($key, &$message, $params) {
  $account = $params['account'];
  $context = $params['context'];
  $variables = array(
    '%site_name' => variable_get('site_name', 'Drupal'),
    '%username' => $account->name,
  );
  if ($context['hook'] == 'taxonomy') {
    $object = $params['object'];
    $vocabulary = taxonomy_vocabulary_load($object->vid);
    $variables += array(
      '%term_name' => $object->name,
      '%term_description' => $object->description,
      '%term_id' => $object->tid,
      '%vocabulary_name' => $vocabulary->name,
      '%vocabulary_description' => $vocabulary->description,
      '%vocabulary_id' => $vocabulary->vid,
    );
  }

  // Node-based variable translation is only available if we have a node.
  if (isset($params['node'])) {
    $node = $params['node'];
    $variables += array(
      '%uid' => $node->uid,
      '%node_url' => url('node/' . $node->nid, array('absolute' => TRUE)),
      '%node_type' => node_get_types('name', $node),
      '%title' => $node->title,
      '%teaser' => $node->teaser,
      '%body' => $node->body,
    );
  }
  $subject = strtr($context['subject'], $variables);
  $body = strtr($context['message'], $variables);
  $message['subject'] .= str_replace(array("\r", "\n"), '', $subject);
  $message['body'][] = drupal_html_to_text($body);
}

/**
 * Add a list of cache tables to be cleared.
 *
 * This hook allows your module to add cache table names to the list of cache
 * tables that will be cleared by the Clear button on the Performance page or
 * whenever drupal_flush_all_caches is invoked.
 *
 * @see drupal_flush_all_caches()
 *
 * @param None.
 *
 * @return
 *   An array of cache table names.
 */
function hook_flush_caches() {
  return array('cache_example');
}

/**
 * Perform necessary actions after modules are installed.
 *
 * This function differs from hook_install() as it gives all other
 * modules a chance to perform actions when a module is installed,
 * whereas hook_install() will only be called on the module actually
 * being installed.
 *
 * @see hook_install()
 *
 * @param $modules
 *   An array of the installed modules.
 */
function hook_modules_installed($modules) {
  if (in_array('lousy_module', $modules)) {
    variable_set('lousy_module_conflicting_variable', FALSE);
  }
}

/**
 * Perform necessary actions after modules are enabled.
 *
 * This function differs from hook_enable() as it gives all other
 * modules a chance to perform actions when modules are enabled,
 * whereas hook_enable() will only be called on the module actually
 * being enabled.
 *
 * @see hook_enable()
 *
 * @param $modules
 *   An array of the enabled modules.
 */
function hook_modules_enabled($modules) {
  if (in_array('lousy_module', $modules)) {
    drupal_set_message(t('mymodule is not compatible with lousy_module'), 'error');
    mymodule_disable_functionality();
  }
}

/**
 * Perform necessary actions after modules are disabled.
 *
 * This function differs from hook_disable() as it gives all other
 * modules a chance to perform actions when modules are disabled,
 * whereas hook_disable() will only be called on the module actually
 * being disabled.
 *
 * @see hook_disable()
 *
 * @param $modules
 *   An array of the disabled modules.
 */
function hook_modules_disabled($modules) {
  if (in_array('lousy_module', $modules)) {
    mymodule_enable_functionality();
  }
}

/**
 * Perform necessary actions after modules are uninstalled.
 *
 * This function differs from hook_uninstall() as it gives all other
 * modules a chance to perform actions when a module is uninstalled,
 * whereas hook_uninstall() will only be called on the module actually
 * being uninstalled.
 *
 * It is recommended that you implement this module if your module
 * stores data that may have been set by other modules.
 *
 * @see hook_uninstall()
 *
 * @param $modules
 *   The name of the uninstalled module.