lib/outputrequirementslib.php

   1 <?php
   2
   3 // This file is part of Moodle - http://moodle.org/
   4 //
   5 // Moodle is free software: you can redistribute it and/or modify
   6 // it under the terms of the GNU General Public License as published by
   7 // the Free Software Foundation, either version 3 of the License, or
   8 // (at your option) any later version.
   9 //
  10 // Moodle is distributed in the hope that it will be useful,
  11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 // GNU General Public License for more details.
  14 //
  15 // You should have received a copy of the GNU General Public License
  16 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  17
  18
  19 /**
  20  * Library functions to facilitate the use of JavaScript in Moodle.
  21  *
  22  * @package    core
  23  * @subpackage lib
  24  * @copyright  2009 Tim Hunt, 2010 Petr Skoda
  25  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  26  */
  27
  28 defined('MOODLE_INTERNAL') || die();
  29
  30 // note: you can find history of this file in lib/ajax/ajaxlib.php
  31
  32 /**
  33  * This class tracks all the things that are needed by the current page.
  34  *
  35  * Normally, the only instance of this  class you will need to work with is the
  36  * one accessible via $PAGE->requires.
  37  *
  38  * Typical usage would be
  39  * <pre>
  40  *     $PAGE->requires->js_init_call('M.mod_forum.init_view');
  41  * </pre>
  42  *
  43  * It also supports obsoleted coding style withouth YUI3 modules.
  44  * <pre>
  45  *     $PAGE->requires->css('/mod/mymod/userstyles.php?id='.$id); // not overridable via themes!
  46  *     $PAGE->requires->js('/mod/mymod/script.js');
  47  *     $PAGE->requires->js('/mod/mymod/small_but_urgent.js', true);
  48  *     $PAGE->requires->js_function_call('init_mymod', array($data), true);
  49  * </pre>
  50  *
  51  * There are some natural restrictions on some methods. For example, {@link css()}
  52  * can only be called before the <head> tag is output. See the comments on the
  53  * individual methods for details.
  54  *
  55  * @copyright 2009 Tim Hunt, 2010 Petr Skoda
  56  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  57  * @since Moodle 2.0
  58  */
  59 class page_requirements_manager {
  60     /** List of string available from JS */
  61     protected $stringsforjs = array();
  62     /** List of JS variables to be initialised */
  63     protected $jsinitvariables = array('head'=>array(), 'footer'=>array());
  64     /** Included JS scripts */
  65     protected $jsincludes = array('head'=>array(), 'footer'=>array());
  66     /** List of needed function calls */
  67     protected $jscalls = array('normal'=>array(), 'ondomready'=>array());
  68     /**
  69      * List of skip links, those are needed for accessibility reasons
  70      * @var array
  71      */
  72     protected $skiplinks = array();
  73     /**
  74      * Javascript code used for initialisation of page, it should be relatively small
  75      * @var array
  76      */
  77     protected $jsinitcode = array();
  78     /**
  79      * Theme sheets, initialised only from core_renderer
  80      * @var array of moodle_url
  81      */
  82     protected $cssthemeurls = array();
  83     /**
  84      * List of custom theme sheets, these are strongly discouraged!
  85      * Useful mostly only for CSS submitted by teachers that is not part of the theme.
  86      * @var array of moodle_url
  87      */
  88     protected $cssurls = array();
  89     /**
  90      * List of requested event handlers
  91      * @var array
  92      */
  93     protected $eventhandlers = array();
  94     /**
  95      * Extra modules
  96      * @var array
  97      */
  98     protected $extramodules = array();
  99     /** Flag indicated head stuff already printed */
 100     protected $headdone = false;
 101     /** Flag indicating top of body already printed */
 102     protected $topofbodydone = false;
 103
 104     /** YUI PHPLoader instance responsible for YUI2 loading from PHP only */
 105     protected $yui2loader;
 106     /** YUI PHPLoader instance responsible for YUI3 loading from PHP only */
 107     protected $yui3loader;
 108     /** YUI loader information for YUI3 loading from javascript */
 109     protected $M_yui_loader;
 110     /** some config vars exposed in JS, please no secret stuff there */
 111     protected $M_cfg;
 112     /** stores debug backtraces from when JS modules were included in the page */
 113     protected $debug_moduleloadstacktraces = array();
 114
 115     /**
 116      * Page requirements constructor.
 117      */
 118     public function __construct() {
 119         global $CFG;
 120
 121         require_once("$CFG->libdir/yui/phploader/phploader/loader.php");
 122
 123         $this->yui3loader = new stdClass();
 124         $this->yui2loader = new YAHOO_util_Loader($CFG->yui2version);
 125
 126         // set up some loader options
 127         if (debugging('', DEBUG_DEVELOPER)) {
 128             $this->yui3loader->filter = YUI_RAW; // for more detailed logging info use YUI_DEBUG here
 129             $this->yui2loader->filter = YUI_RAW; // for more detailed logging info use YUI_DEBUG here
 130         } else {
 131             $this->yui3loader->filter = null;
 132             $this->yui2loader->filter = null;
 133         }
 134         if (!empty($CFG->useexternalyui)) {
 135             $this->yui3loader->base = 'http://yui.yahooapis.com/' . $CFG->yui3version . '/build/';
 136             $this->yui2loader->base = 'http://yui.yahooapis.com/' . $CFG->yui2version . '/build/';
 137             $this->yui3loader->comboBase = 'http://yui.yahooapis.com/combo?';
 138             $this->yui2loader->comboBase = 'http://yui.yahooapis.com/combo?';
 139         } else {
 140             $this->yui3loader->base = $CFG->httpswwwroot . '/lib/yui/'. $CFG->yui3version . '/build/';
 141             $this->yui2loader->base = $CFG->httpswwwroot . '/lib/yui/'. $CFG->yui2version . '/build/';
 142             $this->yui3loader->comboBase = $CFG->httpswwwroot . '/theme/yui_combo.php?';
 143             $this->yui2loader->comboBase = $CFG->httpswwwroot . '/theme/yui_combo.php?';
 144         }
 145
 146         // enable combo loader? this significantly helps with caching and performance!
 147         $this->yui3loader->combine = !empty($CFG->yuicomboloading);
 148         $this->yui2loader->combine = !empty($CFG->yuicomboloading);
 149
 150         if (empty($CFG->cachejs)) {
 151             $jsrev = -1;
 152         } else if (empty($CFG->jsrev)) {
 153             $jsrev = 1;
 154         } else {
 155             $jsrev = $CFG->jsrev;
 156         }
 157
 158         // set up JS YUI loader helper object
 159         $this->M_yui_loader = new stdClass();
 160         $this->M_yui_loader->base         = $this->yui3loader->base;
 161         $this->M_yui_loader->comboBase    = $this->yui3loader->comboBase;
 162         $this->M_yui_loader->combine      = $this->yui3loader->combine;
 163         $this->M_yui_loader->filter       = ($this->yui3loader->filter == YUI_DEBUG) ? 'debug' : '';
 164         $this->M_yui_loader->insertBefore = 'firstthemesheet';
 165         $this->M_yui_loader->modules      = array();
 166         $this->M_yui_loader->groups       = array(
 167             'moodle' => array(
 168                 'name' => 'moodle',
 169                 'base' => $CFG->httpswwwroot . '/theme/yui_combo.php?moodle/'.$jsrev.'/',
 170                 'comboBase' => $CFG->httpswwwroot . '/theme/yui_combo.php?',
 171                 'combine' => $this->yui3loader->combine,
 172                 'filter' => '',
 173                 'ext' => false,
 174                 'root' => 'moodle/'.$jsrev.'/', // Add the rev to the root path so that we can control caching
 175                 'patterns' => array(
 176                     'moodle-' => array(
 177                         'group' => 'moodle',
 178                         'configFn' => '@MOODLECONFIGFN@'
 179                     ),
 180                     'root' => 'moodle'
 181                 )
 182             ),
 183             'local' => array(
 184                 'name' => 'gallery',
 185                 'base' => $CFG->wwwroot.'/lib/yui/gallery/',
 186                 'comboBase' => $CFG->httpswwwroot . '/theme/yui_combo.php?',
 187                 'combine' => $this->yui3loader->combine,
 188                 'filter' => $this->M_yui_loader->filter,
 189                 'ext' => false,
 190                 'root' => 'gallery/',
 191                 'patterns' => array(
 192                     'gallery-' => array(
 193                         'group' => 'gallery',
 194                         'configFn' => '@GALLERYCONFIGFN@',
 195                     ),
 196                     'root' => 'gallery'
 197                 )
 198             )
 199         );
 200         $this->add_yui2_modules(); // adds loading info for all YUI2 modules
 201         $this->js_module($this->find_module('core_filepicker'));
 202         $this->js_module($this->find_module('core_dock'));
 203
 204     }
 205
 206     /**
 207      * This method adds yui2 modules into the yui3 JS loader-
 208      * @return void
 209      */
 210     protected function add_yui2_modules() {
 211         //note: this function is definitely not perfect, because
 212         //      it adds tons of markup into each page, but it can be
 213         //      abstracted into separate JS file with proper headers
 214         global $CFG;
 215
 216         $GLOBALS['yui_current'] = array();
 217         require($CFG->libdir.'/yui/phploader/lib/meta/config_'.$CFG->yui2version.'.php');
 218         $info = $GLOBALS['yui_current'];
 219         unset($GLOBALS['yui_current']);
 220
 221         if (empty($CFG->yuicomboloading)) {
 222             $urlbase = $this->yui2loader->base;
 223         } else {
 224             $urlbase = $this->yui2loader->comboBase.$CFG->yui2version.'/build/';
 225         }
 226
 227         $modules = array();
 228         $ignored = array(); // list of CSS modules that are not needed
 229         foreach ($info['moduleInfo'] as $name => $module) {
 230             if ($module['type'] === 'css') {
 231                 $ignored[$name] = true;
 232             } else {
 233                 $modules['yui2-'.$name] = $module;
 234             }
 235         }
 236         foreach ($modules as $name=>$module) {
 237             $module['fullpath'] = $urlbase.$module['path']; // fix path to point to correct location
 238             unset($module['path']);
 239             unset($module['skinnable']); // we load all YUI2 css automatically, this prevents weird missing css loader problems
 240             foreach(array('requires', 'optional', 'supersedes') as $fixme) {
 241                 if (!empty($module[$fixme])) {
 242                     $fixed = false;
 243                     foreach ($module[$fixme] as $key=>$dep) {
 244                         if (isset($ignored[$dep])) {
 245                             unset($module[$fixme][$key]);
 246                             $fixed = true;
 247                         } else {
 248                             $module[$fixme][$key] = 'yui2-'.$dep;
 249                         }
 250                     }
 251                     if ($fixed) {
 252                         $module[$fixme] = array_merge($module[$fixme]); // fix keys
 253                     }
 254                 }
 255             }
 256             $this->M_yui_loader->modules[$name] = $module;
 257             if (debugging('', DEBUG_DEVELOPER)) {
 258                 if (!array_key_exists($name, $this->debug_moduleloadstacktraces)) {
 259                     $this->debug_moduleloadstacktraces[$name] = array();
 260                 }
 261                 $this->debug_moduleloadstacktraces[$name][] = format_backtrace(debug_backtrace());
 262             }
 263         }
 264     }
 265
 266     /**
 267      * Initialise with the bits of JavaScript that every Moodle page should have.
 268      *
 269      * @param moodle_page $page
 270      * @param core_renderer $output
 271      */
 272     protected function init_requirements_data(moodle_page $page, core_renderer $renderer) {
 273         global $CFG;
 274
 275         // JavaScript should always work with $CFG->httpswwwroot rather than $CFG->wwwroot.
 276         // Otherwise, in some situations, users will get warnings about insecure content
 277         // on secure pages from their web browser.
 278
 279         $this->M_cfg = array(
 280             'wwwroot'             => $CFG->httpswwwroot, // Yes, really. See above.
 281             'sesskey'             => sesskey(),
 282             'loadingicon'         => $renderer->pix_url('i/loading_small', 'moodle')->out(false),
 283             'themerev'            => theme_get_revision(),
 284             'theme'               => $page->theme->name,
 285             'jsrev'               => ((empty($CFG->cachejs) or empty($CFG->jsrev)) ? -1 : $CFG->jsrev),
 286         );
 287         if (debugging('', DEBUG_DEVELOPER)) {
 288             $this->M_cfg['developerdebug'] = true;
 289             $this->yui2_lib('logger');
 290         }
 291
 292         // accessibility stuff
 293         $this->skip_link_to('maincontent', get_string('tocontent', 'access'));
 294
 295         // to be removed soon
 296         $this->yui2_lib('dom');        // at least javascript-static.js needs to be migrated to YUI3
 297
 298         $this->string_for_js('confirmation', 'admin');
 299         $this->string_for_js('cancel', 'moodle');
 300         $this->string_for_js('yes', 'moodle');
 301
 302         if ($page->pagelayout === 'frametop') {
 303             $this->js_init_call('M.util.init_frametop');
 304         }
 305     }
 306
 307     /**
 308      * Ensure that the specified JavaScript file is linked to from this page.
 309      *
 310      * NOTE: This function is to be used in rare cases only, please store your JS in module.js file
 311      * and use $PAGE->requires->js_init_call() instead.
 312      *
 313      * By default the link is put at the end of the page, since this gives best page-load performance.
 314      *
 315      * Even if a particular script is requested more than once, it will only be linked
 316      * to once.
 317      *
 318      * @param string|moodle_url $url The path to the .js file, relative to $CFG->dirroot / $CFG->wwwroot.
 319      *      For example '/mod/mymod/customscripts.js'; use moodle_url for external scripts
 320      * @param bool $inhead initialise in head
 321      * @return void
 322      */
 323     public function js($url, $inhead=false) {
 324         $url = $this->js_fix_url($url);
 325         $where = $inhead ? 'head' : 'footer';
 326         $this->jsincludes[$where][$url->out()] = $url;
 327     }
 328
 329     /**
 330      * Ensure that the specified YUI2 library file, and all its required dependencies,
 331      * are linked to from this page.
 332      *
 333      * By default the link is put at the end of the page, since this gives best page-load
 334      * performance. Optional dependencies are not loaded automatically - if you want
 335      * them you will need to load them first with other calls to this method.
 336      *
 337      * Even if a particular library is requested more than once (perhaps as a dependency
 338      * of other libraries) it will only be linked to once.
 339      *
 340      * The library is leaded as soon as possible, if $OUTPUT->header() not used yet it
 341      * is put into the page header, otherwise it is loaded in the page footer.
 342      *
 343      * @param string|array $libname the name of the YUI2 library you require. For example 'autocomplete'.
 344      * @return void
 345      */
 346     public function yui2_lib($libname) {
 347         $libnames = (array)$libname;
 348         foreach ($libnames as $lib) {
 349             $this->yui2loader->load($lib);
 350         }
 351     }
 352
 353     /**
 354      * Returns the actual url through which a script is served.
 355      * @param moodle_url|string $url full moodle url, or shortened path to script
 356      * @return moodle_url
 357      */
 358     protected function js_fix_url($url) {
 359         global $CFG;
 360
 361         if ($url instanceof moodle_url) {
 362             return $url;
 363         } else if (strpos($url, '/') === 0) {
 364             if (debugging()) {
 365                 // check file existence only when in debug mode
 366                 if (!file_exists($CFG->dirroot . strtok($url, '?'))) {
 367                     throw new coding_exception('Attempt to require a JavaScript file that does not exist.', $url);
 368                 }
 369             }
 370             if (!empty($CFG->cachejs) and !empty($CFG->jsrev) and strpos($url, '/lib/editor/') !== 0 and substr($url, -3) === '.js') {
 371                 return new moodle_url($CFG->httpswwwroot.'/lib/javascript.php', array('file'=>$url, 'rev'=>$CFG->jsrev));
 372             } else {
 373                 return new moodle_url($CFG->httpswwwroot.$url);
 374             }
 375         } else {
 376             throw new coding_exception('Invalid JS url, it has to be shortened url starting with / or moodle_url instance.', $url);
 377         }
 378     }
 379
 380     /**
 381      * Find out if JS module present and return details.
 382      * @param string $component name of component in frankenstyle, ex: core_group, mod_forum
 383      * @return array description of module or null if not found
 384      */
 385     protected function find_module($component) {
 386         global $CFG;
 387
 388         $module = null;
 389
 390
 391         if (strpos($component, 'core_') === 0) {
 392             // must be some core stuff - list here is not complete, this is just the stuff used from multiple places
 393             // so that we do nto have to repeat the definition of these modules over and over again
 394             switch($component) {
 395                 case 'core_filepicker':
 396                     $module = array('name'     => 'core_filepicker',
 397                                     'fullpath' => '/repository/filepicker.js',
 398                                     'requires' => array('base', 'node', 'node-event-simulate', 'json', 'async-queue', 'io-base', 'io-upload-iframe', 'io-form', 'yui2-button', 'yui2-container', 'yui2-layout', 'yui2-menu', 'yui2-treeview', 'yui2-dragdrop', 'yui2-cookie'),
 399                                     'strings'  => array(array('add', 'repository'), array('back', 'repository'), array('cancel', 'moodle'), array('close', 'repository'),
 400                                                         array('cleancache', 'repository'), array('copying', 'repository'), array('date', 'repository'), array('downloadsucc', 'repository'),
 401                                                         array('emptylist', 'repository'), array('error', 'repository'), array('federatedsearch', 'repository'),
 402                                                         array('filenotnull', 'repository'), array('getfile', 'repository'), array('help', 'moodle'), array('iconview', 'repository'),
 403                                                         array('invalidjson', 'repository'), array('linkexternal', 'repository'), array('listview', 'repository'),
 404                                                         array('loading', 'repository'), array('login', 'repository'), array('logout', 'repository'), array('noenter', 'repository'),
 405                                                         array('noresult', 'repository'), array('manageurl', 'repository'), array('popup', 'repository'), array('preview', 'repository'),
 406                                                         array('refresh', 'repository'), array('save', 'repository'), array('saveas', 'repository'), array('saved', 'repository'),
 407                                                         array('saving', 'repository'), array('search', 'repository'), array('searching', 'repository'), array('size', 'repository'),
 408                                                         array('submit', 'repository'), array('sync', 'repository'), array('title', 'repository'), array('upload', 'repository'),
 409                                                         array('uploading', 'repository'), array('xhtmlerror', 'repository'),
 410                                                         array('cancel'), array('chooselicense', 'repository'), array('author', 'repository'),
 411                                                         array('ok', 'moodle'), array('error', 'moodle'), array('info', 'moodle'), array('norepositoriesavailable', 'repository'), array('norepositoriesexternalavailable', 'repository'),
 412                                                         array('nofilesattached', 'repository'), array('filepicker', 'repository'),
 413                                                         array('nofilesavailable', 'repository'), array('overwrite', 'repository'),
 414                                                         array('renameto', 'repository'), array('fileexists', 'repository'),
 415                                                         array('fileexistsdialogheader', 'repository'), array('fileexistsdialog_editor', 'repository'),
 416                                                         array('fileexistsdialog_filemanager', 'repository')
 417                                                     ));
 418                     break;
 419                 case 'core_comment':
 420                     $module = array('name'     => 'core_comment',
 421                                     'fullpath' => '/comment/comment.js',
 422                                     'requires' => array('base', 'io-base', 'node', 'json', 'yui2-animation', 'overlay'),
 423                                     'strings' => array(array('confirmdeletecomments', 'admin'), array('yes', 'moodle'), array('no', 'moodle'))
 424                                 );
 425                     break;
 426                 case 'core_role':
 427                     $module = array('name'     => 'core_role',
 428                                     'fullpath' => '/admin/roles/module.js',
 429                                     'requires' => array('node', 'cookie'));
 430                     break;
 431                 case 'core_completion':
 432                     $module = array('name'     => 'core_completion',
 433                                     'fullpath' => '/course/completion.js');
 434                     break;
 435                 case 'core_dock':
 436                     $module = array('name'     => 'core_dock',
 437                                     'fullpath' => '/blocks/dock.js',
 438                                     'requires' => array('base', 'node', 'event-custom', 'event-mouseenter', 'event-resize'),
 439                                     'strings' => array(array('addtodock', 'block'),array('undockitem', 'block'),array('undockall', 'block'),array('thisdirectionvertical', 'langconfig')));
 440                     break;
 441                 case 'core_message':
 442                     $module = array('name'     => 'core_message',
 443                                     'requires' => array('base', 'node', 'event', 'node-event-simulate'),
 444                                     'fullpath' => '/message/module.js');
 445                     break;
 446                 case 'core_group':
 447                     $module = array('name'     => 'core_group',
 448                                     'fullpath' => '/group/module.js',
 449                                     'requires' => array('node', 'overlay', 'event-mouseenter'));
 450                     break;
 451                 case 'core_question_engine':
 452                     $module = array('name'     => 'core_question_engine',
 453                                     'fullpath' => '/question/qengine.js',
 454                                     'requires' => array('node', 'event'));
 455                     break;
 456                 case 'core_rating':
 457                     $module = array('name'     => 'core_rating',
 458                                     'fullpath' => '/rating/module.js',
 459                                     'requires' => array('node', 'event', 'overlay', 'io-base', 'json'));
 460                     break;
 461                 case 'core_filetree':
 462                     $module = array('name'     => 'core_filetree',
 463                                     'fullpath' => '/files/module.js',
 464                                     'requires' => array('node', 'event', 'overlay', 'io-base', 'json', 'yui2-treeview'));
 465                     break;
 466             }
 467
 468         } else {
 469             if ($dir = get_component_directory($component)) {
 470                 if (file_exists("$dir/module.js")) {
 471                     if (strpos($dir, $CFG->dirroot.'/') === 0) {
 472                         $dir = substr($dir, strlen($CFG->dirroot));
 473                         $module = array('name'=>$component, 'fullpath'=>"$dir/module.js", 'requires' => array());
 474                     }
 475                 }
 476             }
 477         }
 478
 479         return $module;
 480     }
 481
 482     /**
 483      * Append YUI3 module to default YUI3 JS loader.
 484      * The structure of module array is described at http://developer.yahoo.com/yui/3/yui/:
 485      * @param string|array $module name of module (details are autodetected), or full module specification as array
 486      * @return void
 487      */
 488     public function js_module($module) {
 489         global $CFG;
 490
 491         if (empty($module)) {
 492             throw new coding_exception('Missing YUI3 module name or full description.');
 493         }
 494
 495         if (is_string($module)) {
 496             $module = $this->find_module($module);
 497         }
 498
 499         if (empty($module) or empty($module['name']) or empty($module['fullpath'])) {
 500             throw new coding_exception('Missing YUI3 module details.');
 501         }
 502
 503         // Don't load this module if we already have, no need to!
 504         if ($this->js_module_loaded($module['name'])) {
 505             if (debugging('', DEBUG_DEVELOPER)) {
 506                 $this->debug_moduleloadstacktraces[$module['name']][] = format_backtrace(debug_backtrace());
 507             }
 508             return;
 509         }
 510
 511         $module['fullpath'] = $this->js_fix_url($module['fullpath'])->out(false);
 512         // add all needed strings
 513         if (!empty($module['strings'])) {
 514             foreach ($module['strings'] as $string) {
 515                 $identifier = $string[0];
 516                 $component = isset($string[1]) ? $string[1] : 'moodle';
 517                 $a = isset($string[2]) ? $string[2] : null;
 518                 $this->string_for_js($identifier, $component, $a);
 519             }
 520         }
 521         unset($module['strings']);
 522
 523         // Process module requirements and attempt to load each. This allows
 524         // moodle modules to require each other.
 525         if (!empty($module['requires'])){
 526             foreach ($module['requires'] as $requirement) {
 527                 $rmodule = $this->find_module($requirement);
 528                 if (is_array($rmodule)) {
 529                     $this->js_module($rmodule);
 530                 }
 531             }
 532         }
 533
 534         if ($this->headdone) {
 535             $this->extramodules[$module['name']] = $module;
 536         } else {
 537             $this->M_yui_loader->modules[$module['name']] = $module;
 538         }
 539         if (debugging('', DEBUG_DEVELOPER)) {
 540             if (!array_key_exists($module['name'], $this->debug_moduleloadstacktraces)) {
 541                 $this->debug_moduleloadstacktraces[$module['name']] = array();
 542             }
 543             $this->debug_moduleloadstacktraces[$module['name']][] = format_backtrace(debug_backtrace());
 544         }
 545     }
 546
 547     /**
 548      * Returns true if the module has already been loaded.
 549      *
 550      * @param string|array $modulename
 551      * @return bool True if the module has already been loaded
 552      */
 553     protected function js_module_loaded($module) {
 554         if (is_string($module)) {
 555             $modulename = $module;
 556         } else {
 557             $modulename = $module['name'];
 558         }
 559         return array_key_exists($modulename, $this->M_yui_loader->modules) ||
 560                array_key_exists($modulename, $this->extramodules);
 561     }
 562
 563     /**
 564      * Returns the stacktraces from loading js modules.
 565      * @return array
 566      */
 567     public function get_loaded_modules() {
 568         return $this->debug_moduleloadstacktraces;
 569     }
 570
 571     /**
 572      * Ensure that the specified CSS file is linked to from this page.
 573      *
 574      * Because stylesheet links must go in the <head> part of the HTML, you must call
 575      * this function before {@link get_head_code()} is called. That normally means before
 576      * the call to print_header. If you call it when it is too late, an exception
 577      * will be thrown.
 578      *
 579      * Even if a particular style sheet is requested more than once, it will only
 580      * be linked to once.
 581      *
 582      * Please note use of this feature is strongly discouraged,
 583      * it is suitable only for places where CSS is submitted directly by teachers.
 584      * (Students must not be allowed to submit any external CSS because it may
 585      * contain embedded javascript!). Example of correct use is mod/data.
 586      *
 587      * @param string $stylesheet The path to the .css file, relative to $CFG->wwwroot.
 588      *   For example:
 589      *      $PAGE->requires->css('mod/data/css.php?d='.$data->id);
 590      */
 591     public function css($stylesheet) {
 592         global $CFG;
 593
 594         if ($this->headdone) {
 595             throw new coding_exception('Cannot require a CSS file after &lt;head> has been printed.', $stylesheet);
 596         }
 597
 598         if ($stylesheet instanceof moodle_url) {
 599             // ok
 600         } else if (strpos($stylesheet, '/') === 0) {
 601             $stylesheet = new moodle_url($CFG->httpswwwroot.$stylesheet);
 602         } else {
 603             throw new coding_exception('Invalid stylesheet parameter.', $stylesheet);
 604         }
 605
 606         $this->cssurls[$stylesheet->out()] = $stylesheet; // overrides
 607     }
 608
 609     /**
 610      * Add theme stylkesheet to page - do not use from plugin code,
 611      * this should be called only from the core renderer!
 612      * @param moodle_url $stylesheet
 613      * @return void
 614      */
 615     public function css_theme(moodle_url $stylesheet) {
 616         $this->cssthemeurls[] = $stylesheet;
 617     }
 618
 619     /**
 620      * Ensure that a skip link to a given target is printed at the top of the <body>.
 621      *
 622      * You must call this function before {@link get_top_of_body_code()}, (if not, an exception
 623      * will be thrown). That normally means you must call this before the call to print_header.
 624      *
 625      * If you ask for a particular skip link to be printed, it is then your responsibility
 626      * to ensure that the appropriate <a name="..."> tag is printed in the body of the
 627      * page, so that the skip link goes somewhere.
 628      *
 629      * Even if a particular skip link is requested more than once, only one copy of it will be output.
 630      *
 631      * @param $target the name of anchor this link should go to. For example 'maincontent'.
 632      * @param $linktext The text to use for the skip link. Normally get_string('skipto', 'access', ...);
 633      */
 634     public function skip_link_to($target, $linktext) {
 635         if ($this->topofbodydone) {
 636             debugging('Page header already printed, can not add skip links any more, code needs to be fixed.');
 637             return;
 638         }
 639         $this->skiplinks[$target] = $linktext;
 640     }
 641
 642     /**
 643      * !!!DEPRECATED!!! please use js_init_call() if possible
 644      * Ensure that the specified JavaScript function is called from an inline script
 645      * somewhere on this page.
 646      *
 647      * By default the call will be put in a script tag at the
 648      * end of the page after initialising Y instance, since this gives best page-load
 649      * performance and allows you to use YUI3 library.
 650      *
 651      * If you request that a particular function is called several times, then
 652      * that is what will happen (unlike linking to a CSS or JS file, where only
 653      * one link will be output).
 654      *
 655      * The main benefit of the method is the automatic encoding of all function parameters.
 656      *
 657      * @param string $function the name of the JavaScritp function to call. Can
 658      *      be a compound name like 'Y.Event.purgeElement'. Can also be
 659      *      used to create and object by using a 'function name' like 'new user_selector'.
 660      * @param array $arguments and array of arguments to be passed to the function.
 661      *      When generating the function call, this will be escaped using json_encode,
 662      *      so passing objects and arrays should work.
 663      * @param bool $ondomready
 664      * @param int $delay
 665      * @return void
 666      */
 667     public function js_function_call($function, array $arguments = null, $ondomready = false, $delay = 0) {
 668         $where = $ondomready ? 'ondomready' : 'normal';
 669         $this->jscalls[$where][] = array($function, $arguments, $delay);
 670     }
 671
 672     /**
 673      * Adds a call to make use of a YUI gallery module. DEPRECATED DO NOT USE!!!
 674      *
 675      * @deprecated DO NOT USE
 676      *
 677      * @param string|array $modules One or more gallery modules to require
 678      * @param string $version
 679      * @param string $function
 680      * @param array $arguments
 681      * @param bool $ondomready
 682      */
 683     public function js_gallery_module($modules, $version, $function, array $arguments = null, $ondomready = false) {
 684         global $CFG;
 685         debugging('This function will be removed before 2.0 is released please change it from js_gallery_module to yui_module', DEBUG_DEVELOPER);
 686         $this->yui_module($modules, $function, $arguments, $version, $ondomready);
 687     }
 688
 689     /**
 690      * Creates a JavaScript function call that requires one or more modules to be loaded
 691      *
 692      * This function can be used to include all of the standard YUI module types within JavaScript:
 693      *     - YUI3 modules    [node, event, io]
 694      *     - YUI2 modules    [yui2-*]
 695      *     - Moodle modules  [moodle-*]
 696      *     - Gallery modules [gallery-*]
 697      *
 698      * @param array|string $modules One or more modules
 699      * @param string $function The function to call once modules have been loaded
 700      * @param array $arguments An array of arguments to pass to the function
 701      * @param string $galleryversion The gallery version to use
 702      * @param bool $ondomready
 703      */
 704     public function yui_module($modules, $function, array $arguments = null, $galleryversion = '2010.04.08-12-35', $ondomready = false) {
 705         global $CFG;
 706
 707         if (!is_array($modules)) {
 708             $modules = array($modules);
 709         }
 710         if (empty($CFG->useexternalyui) || true) {
 711             // We need to set the M.yui.galleryversion to the correct version
 712             $jscode = 'M.yui.galleryversion='.json_encode($galleryversion).';';
 713         } else {
 714             // Set Y's config.gallery to the version
 715             $jscode = 'Y.config.gallery='.json_encode($galleryversion).';';
 716         }
 717         $jscode .= 'Y.use('.join(',', array_map('json_encode', $modules)).',function() {'.js_writer::function_call($function, $arguments).'});';
 718         if ($ondomready) {
 719             $jscode = "Y.on('domready', function() { $jscode });";
 720         }
 721         $this->jsinitcode[] = $jscode;
 722     }
 723
 724     /**
 725      * Ensure that the specified JavaScript function is called from an inline script
 726      * from page footer.
 727      *
 728      * @param string $function the name of the JavaScritp function to with init code,
 729      *      usually something like 'M.mod_mymodule.init'
 730      * @param array $extraarguments and array of arguments to be passed to the function.
 731      *      The first argument is always the YUI3 Y instance with all required dependencies
 732      *      already loaded.
 733      * @param bool $ondomready wait for dom ready (helps with some IE problems when modifying DOM)
 734      * @param array $module JS module specification array
 735      * @return void
 736      */
 737     public function js_init_call($function, array $extraarguments = null, $ondomready = false, array $module = null) {
 738         $jscode = js_writer::function_call_with_Y($function, $extraarguments);
 739         if (!$module) {
 740             // detect module automatically
 741             if (preg_match('/M\.([a-z0-9]+_[^\.]+)/', $function, $matches)) {
 742                 $module = $this->find_module($matches[1]);
 743             }
 744         }
 745
 746         $this->js_init_code($jscode, $ondomready, $module);
 747     }
 748
 749     /**
 750      * Add short static javascript code fragment to page footer.
 751      * This is intended primarily for loading of js modules and initialising page layout.
 752      * Ideally the JS code fragment should be stored in plugin renderer so that themes
 753      * may override it.
 754      * @param string $jscode
 755      * @param bool $ondomready wait for dom ready (helps with some IE problems when modifying DOM)
 756      * @param array $module JS module specification array
 757      * @return void
 758      */
 759     public function js_init_code($jscode, $ondomready = false, array $module = null) {
 760         $jscode = trim($jscode, " ;\n"). ';';
 761
 762         if ($module) {
 763             $this->js_module($module);
 764             $modulename = $module['name'];
 765             $jscode = "Y.use('$modulename', function(Y) { $jscode });";
 766         }
 767
 768         if ($ondomready) {
 769             $jscode = "Y.on('domready', function() { $jscode });";
 770         }
 771
 772         $this->jsinitcode[] = $jscode;
 773     }
 774
 775     /**
 776      * Make a language string available to JavaScript.
 777      *
 778      * All the strings will be available in a M.str object in the global namespace.
 779      * So, for example, after a call to $PAGE->requires->string_for_js('course', 'moodle');
 780      * then the JavaScript variable M.str.moodle.course will be 'Course', or the
 781      * equivalent in the current language.
 782      *
 783      * The arguments to this function are just like the arguments to get_string
 784      * except that $component is not optional, and there are some aspects to consider
 785      * when the string contains {$a} placeholder.
 786      *
 787      * If the string does not contain any {$a} placeholder, you can simply use
 788      * M.str.component.identifier to obtain it. If you prefer, you can call
 789      * M.util.get_string(identifier, component) to get the same result.
 790      *
 791      * If you need to use {$a} placeholders, there are two options. Either the
 792      * placeholder should be substituted in PHP on server side or it should
 793      * be substituted in Javascript at client side.
 794      *
 795      * To substitute the placeholder at server side, just provide the required
 796      * value for the placeholder when you require the string. Because each string
 797      * is only stored once in the JavaScript (based on $identifier and $module)
 798      * you cannot get the same string with two different values of $a. If you try,
 799      * an exception will be thrown. Once the placeholder is substituted, you can
 800      * use M.str or M.util.get_string() as shown above:
 801      *
 802      *     // require the string in PHP and replace the placeholder
 803      *     $PAGE->requires->string_for_js('fullnamedisplay', 'moodle', $USER);
 804      *     // use the result of the substitution in Javascript
 805      *     alert(M.str.moodle.fullnamedisplay);
 806      *
 807      * To substitute the placeholder at client side, use M.util.get_string()
 808      * function. It implements the same logic as {@see get_string()}:
 809      *
 810      *     // require the string in PHP but keep {$a} as it is
 811      *     $PAGE->requires->string_for_js('fullnamedisplay', 'moodle');
 812      *     // provide the values on the fly in Javascript
 813      *     user = { firstname : 'Harry', lastname : 'Potter' }
 814      *     alert(M.util.get_string('fullnamedisplay', 'moodle', user);
 815      *
 816      * If you do need the same string expanded with different $a values in PHP
 817      * on server side, then the solution is to put them in your own data structure
 818      * (e.g. and array) that you pass to JavaScript with {@link data_for_js()}.
 819      *
 820      * @param string $identifier the desired string.
 821      * @param string $module the language file to look in.
 822      * @param mixed $a any extra data to add into the string (optional).
 823      */
 824     public function string_for_js($identifier, $component, $a = NULL) {
 825         $string = get_string($identifier, $component, $a);
 826         if (!$component) {
 827             throw new coding_exception('The $module parameter is required for page_requirements_manager::string_for_js.');
 828         }
 829         if (isset($this->stringsforjs[$component][$identifier]) && $this->stringsforjs[$component][$identifier] !== $string) {
 830             throw new coding_exception("Attempt to re-define already required string '$identifier' " .
 831                     "from lang file '$component'. Did you already ask for it with a different \$a? {$this->stringsforjs[$component][$identifier]} !== $string");
 832         }
 833         $this->stringsforjs[$component][$identifier] = $string;
 834     }
 835
 836     /**
 837      * Make an array of language strings available for JS
 838      *
 839      * This function calls the above function {@link string_for_js()} for each requested
 840      * string in the $identifiers array that is passed to the argument for a single module
 841      * passed in $module.
 842      *
 843      * <code>
 844      * $PAGE->requires->strings_for_js(array('one', 'two', 'three'), 'mymod', array('a', null, 3));
 845      *
 846      * // The above is identitical to calling
 847      *
 848      * $PAGE->requires->string_for_js('one', 'mymod', 'a');
 849      * $PAGE->requires->string_for_js('two', 'mymod');
 850      * $PAGE->requires->string_for_js('three', 'mymod', 3);
 851      * </code>
 852      *
 853      * @param array $identifiers An array of desired strings
 854      * @param string $component The module to load for
 855      * @param mixed $a This can either be a single variable that gets passed as extra
 856      *         information for every string or it can be an array of mixed data where the
 857      *         key for the data matches that of the identifier it is meant for.
 858      *
 859      */
 860     public function strings_for_js($identifiers, $component, $a=NULL) {
 861         foreach ($identifiers as $key => $identifier) {
 862             if (is_array($a) && array_key_exists($key, $a)) {
 863                 $extra = $a[$key];
 864             } else {
 865                 $extra = $a;
 866             }
 867             $this->string_for_js($identifier, $component, $extra);
 868         }
 869     }
 870
 871     /**
 872      * !!!!!!DEPRECATED!!!!!! please use js_init_call() for everything now.
 873      *
 874      * Make some data from PHP available to JavaScript code.
 875      *
 876      * For example, if you call
 877      * <pre>
 878      *      $PAGE->requires->data_for_js('mydata', array('name' => 'Moodle'));
 879      * </pre>
 880      * then in JavsScript mydata.name will be 'Moodle'.
 881      * @param string $variable the the name of the JavaScript variable to assign the data to.
 882      *      Will probably work if you use a compound name like 'mybuttons.button[1]', but this
 883      *      should be considered an experimental feature.
 884      * @param mixed $data The data to pass to JavaScript. This will be escaped using json_encode,
 885      *      so passing objects and arrays should work.
 886      * @param bool $inhead initialise in head
 887      * @return void
 888      */
 889     public function data_for_js($variable, $data, $inhead=false) {
 890         $where = $inhead ? 'head' : 'footer';
 891         $this->jsinitvariables[$where][] = array($variable, $data);
 892     }
 893
 894     /**
 895      * Creates a YUI event handler.
 896      *
 897      * @param mixed $selector standard YUI selector for elemnts, may be array or string, element id is in the form "#idvalue"
 898      * @param string $event A valid DOM event (click, mousedown, change etc.)
 899      * @param string $function The name of the function to call
 900      * @param array  $arguments An optional array of argument parameters to pass to the function
 901      * @return void
 902      */
 903     public function event_handler($selector, $event, $function, array $arguments = null) {
 904         $this->eventhandlers[] = array('selector'=>$selector, 'event'=>$event, 'function'=>$function, 'arguments'=>$arguments);
 905     }
 906
 907     /**
 908      * Returns code needed for registering of event handlers.
 909      * @return string JS code
 910      */
 911     protected function get_event_handler_code() {
 912         $output = '';
 913         foreach ($this->eventhandlers as $h) {
 914             $output .= js_writer::event_handler($h['selector'], $h['event'], $h['function'], $h['arguments']);
 915         }
 916         return $output;
 917     }
 918
 919     /**
 920      * Get the inline JavaScript code that need to appear in a particular place.
 921      * @return bool $ondomready
 922      */
 923     protected function get_javascript_code($ondomready) {
 924         $where = $ondomready ? 'ondomready' : 'normal';
 925         $output = '';
 926         if ($this->jscalls[$where]) {
 927             foreach ($this->jscalls[$where] as $data) {
 928                 $output .= js_writer::function_call($data[0], $data[1], $data[2]);
 929             }
 930             if (!empty($ondomready)) {
 931                 $output = "    Y.on('domready', function() {\n$output\n    });";
 932             }
 933         }
 934         return $output;
 935     }
 936
 937     /**
 938      * Returns js code to be executed when Y is available.
 939      * @return unknown_type
 940      */
 941     protected function get_javascript_init_code() {
 942         if (count($this->jsinitcode)) {
 943             return implode("\n", $this->jsinitcode) . "\n";
 944         }
 945         return '';
 946     }
 947
 948     /**
 949      * Returns basic YUI3 JS loading code.
 950      * YUI3 is using autoloading of both CSS and JS code.
 951      *
 952      * Major benefit of this compared to standard js/csss loader is much improved
 953      * caching, better browser cache utilisation, much fewer http requests.
 954      *
 955      * @return string
 956      */
 957     protected function get_yui3lib_headcode() {
 958         global $CFG;
 959
 960         $code = '';
 961
 962         if ($this->yui3loader->combine) {
 963             $code .= '<link rel="stylesheet" type="text/css" href="'.$this->yui3loader->comboBase
 964                      .$CFG->yui3version.'/build/cssreset/reset-min.css&amp;'
 965                      .$CFG->yui3version.'/build/cssfonts/fonts-min.css&amp;'
 966                      .$CFG->yui3version.'/build/cssgrids/grids-min.css&amp;'
 967                      .$CFG->yui3version.'/build/cssbase/base-min.css" />';
 968         } else {
 969             $code .= '<link rel="stylesheet" type="text/css" href="'.$this->yui3loader->base.'cssreset/reset-min.css" />';
 970             $code .= '<link rel="stylesheet" type="text/css" href="'.$this->yui3loader->base.'cssfonts/fonts-min.css" />';
 971             $code .= '<link rel="stylesheet" type="text/css" href="'.$this->yui3loader->base.'cssgrids/grids-min.css" />';
 972             $code .= '<link rel="stylesheet" type="text/css" href="'.$this->yui3loader->base.'cssbase/base-min.css" />';
 973         }
 974
 975         if (debugging('', DEBUG_DEVELOPER)) {
 976             $code .= '<script src="'.$this->yui3loader->base.'yui/yui-debug.js"></script>';
 977         } else {
 978             $code .= '<script src="'.$this->yui3loader->base.'yui/yui-min.js"></script>';
 979         }
 980
 981         return $code;
 982     }
 983
 984     /**
 985      * Returns basic YUI2 JS loading code.
 986      * It can be called manually at any time.
 987      * If called manually the result needs to be output using echo().
 988      *
 989      * Major benefit of this compared to standard js loader is much improved
 990      * caching, better browser cache utilisation, much fewer http requests.
 991      *
 992      * All YUI2 CSS is loaded automatically.
 993      *
 994      * @return string JS embedding code
 995      */
 996     public function get_yui2lib_code() {
 997         global $CFG;
 998
 999         if ($this->headdone) {
1000             $code = $this->yui2loader->script();
1001         } else {
1002             $code = $this->yui2loader->script();
1003             if ($this->yui2loader->combine) {
1004                 $skinurl = $this->yui2loader->comboBase . $CFG->yui2version . '/build/assets/skins/sam/skin.css';
1005             } else {
1006                 $skinurl = $this->yui2loader->base . 'assets/skins/sam/skin.css';
1007             }
1008             // please note this is a temporary hack until we fully migrate to later YUI3 that has all the widgets
1009             $attributes = array('rel'=>'stylesheet', 'type'=>'text/css', 'href'=>$skinurl);
1010             $code .= "\n" . html_writer::empty_tag('link', $attributes) . "\n";
1011         }
1012         $code = str_replace('&amp;', '&', $code);
1013         $code = str_replace('&', '&amp;', $code);
1014         return $code;
1015     }
1016
1017     /**
1018      * Returns html tags needed for inclusion of theme CSS
1019      * @return string
1020      */
1021     protected function get_css_code() {
1022         // First of all the theme CSS, then any custom CSS
1023         // Please note custom CSS is strongly discouraged,
1024         // because it can not be overridden by themes!
1025         // It is suitable only for things like mod/data which accepts CSS from teachers.
1026         $attributes = array('rel'=>'stylesheet', 'type'=>'text/css');
1027
1028         // This line of code may look funny but it is currently required in order
1029         // to avoid MASSIVE display issues in Internet Explorer.
1030         // As of IE8 + YUI3.1.1 the reference stylesheet (firstthemesheet) gets
1031         // ignored whenever another resource is added until such time as a redraw
1032         // is forced, usually by moving the mouse over the affected element.
1033         $code = html_writer::tag('script', '/** Required in order to fix style inclusion problems in IE with YUI **/', array('id'=>'firstthemesheet', 'type'=>'text/css'));
1034
1035         $urls = $this->cssthemeurls + $this->cssurls;
1036         foreach ($urls as $url) {
1037             $attributes['href'] = $url;
1038             $code .= html_writer::empty_tag('link', $attributes) . "\n";
1039             // this id is needed in first sheet only so that theme may override YUI sheets laoded on the fly
1040             unset($attributes['id']);
1041         }
1042
1043         return $code;
1044     }
1045
1046     /**
1047      * Adds extra modules specified after printing of page header
1048      */
1049     protected function get_extra_modules_code() {
1050         if (empty($this->extramodules)) {
1051             return '';
1052         }
1053         return html_writer::script(js_writer::function_call('M.yui.add_module', array($this->extramodules)));
1054     }
1055
1056     /**
1057      * Generate any HTML that needs to go inside the <head> tag.
1058      *
1059      * Normally, this method is called automatically by the code that prints the
1060      * <head> tag. You should not normally need to call it in your own code.
1061      *
1062      * @return string the HTML code to to inside the <head> tag.
1063      */
1064     public function get_head_code(moodle_page $page, core_renderer $renderer) {
1065         global $CFG;
1066
1067         // note: the $page and $output are not stored here because it would
1068         // create circular references in memory which prevents garbage collection
1069         $this->init_requirements_data($page, $renderer);
1070
1071         // yui3 JS and CSS is always loaded first - it is cached in browser
1072         $output = $this->get_yui3lib_headcode();
1073
1074         // BC: load basic YUI2 for now, all yui2 things should be loaded via Y.use('yui2-oldmodulename')
1075         $output .= $this->get_yui2lib_code();
1076
1077         // now theme CSS + custom CSS in this specific order
1078         $output .= $this->get_css_code();
1079
1080         // set up global YUI3 loader object - this should contain all code needed by plugins
1081         // note: in JavaScript just use "YUI(M.yui.loader).use('overlay', function(Y) { .... });"
1082         // this needs to be done before including any other script
1083         $js = "var M = {}; M.yui = {}; var moodleConfigFn = function(me) {var p = me.path, b = me.name.replace(/^moodle-/,'').split('-', 3), n = b.pop();if (/(skin|core)/.test(n)) {n = b.pop();me.type = 'css';};me.path = b.join('-')+'/'+n+'/'+n+'.'+me.type;}; var galleryConfigFn = function(me) {var p = me.path,v=M.yui.galleryversion,f;if(/-(skin|core)/.test(me.name)) {me.type = 'css';p = p.replace(/-(skin|core)/, '').replace(/\.js/, '.css').split('/'), f = p.pop().replace(/(\-(min|debug))/, '');if (/-skin/.test(me.name)) {p.splice(p.length,0,v,'assets','skins','sam', f);} else {p.splice(p.length,0,v,'assets', f);};} else {p = p.split('/'), f = p.pop();p.splice(p.length,0,v, f);};me.path = p.join('/');};\n";
1084         $js .= js_writer::set_variable('M.yui.loader', $this->M_yui_loader, false) . "\n";
1085         $js .= js_writer::set_variable('M.cfg', $this->M_cfg, false);
1086         $js = str_replace('"@GALLERYCONFIGFN@"', 'galleryConfigFn', $js);
1087         $js = str_replace('"@MOODLECONFIGFN@"', 'moodleConfigFn', $js);
1088
1089         $output .= html_writer::script($js);
1090
1091         // link our main JS file, all core stuff should be there
1092         $output .= html_writer::script('', $this->js_fix_url('/lib/javascript-static.js'));
1093
1094         // add variables
1095         if ($this->jsinitvariables['head']) {
1096             $js = '';
1097             foreach ($this->jsinitvariables['head'] as $data) {
1098                 list($var, $value) = $data;
1099                 $js .= js_writer::set_variable($var, $value, true);
1100             }
1101             $output .= html_writer::script($js);
1102         }
1103
1104         // all the other linked things from HEAD - there should be as few as possible
1105         if ($this->jsincludes['head']) {
1106             foreach ($this->jsincludes['head'] as $url) {
1107                 $output .= html_writer::script('', $url);
1108             }
1109         }
1110
1111         // mark head sending done, it is not possible to anything there
1112         $this->headdone = true;
1113
1114         return $output;
1115     }
1116
1117     /**
1118      * Generate any HTML that needs to go at the start of the <body> tag.
1119      *
1120      * Normally, this method is called automatically by the code that prints the
1121      * <head> tag. You should not normally need to call it in your own code.
1122      *
1123      * @return string the HTML code to go at the start of the <body> tag.
1124      */
1125     public function get_top_of_body_code() {
1126         // first the skip links
1127         $links = '';
1128         $attributes = array('class'=>'skip');
1129         foreach ($this->skiplinks as $url => $text) {
1130             $attributes['href'] = '#' . $url;
1131             $links .= html_writer::tag('a', $text, $attributes);
1132         }
1133         $output = html_writer::tag('div', $links, array('class'=>'skiplinks')) . "\n";
1134
1135         // then the clever trick for hiding of things not needed when JS works
1136         $output .= html_writer::script("document.body.className += ' jsenabled';") . "\n";
1137         $this->topofbodydone = true;
1138         return $output;
1139     }
1140
1141     /**
1142      * Generate any HTML that needs to go at the end of the page.
1143      *
1144      * Normally, this method is called automatically by the code that prints the
1145      * page footer. You should not normally need to call it in your own code.
1146      *
1147      * @return string the HTML code to to at the end of the page.
1148      */
1149     public function get_end_code() {
1150         global $CFG;
1151         // add other requested modules
1152         $output = $this->get_extra_modules_code();
1153
1154         // add missing YUI2 YUI - to be removed once we convert everything to YUI3!
1155         $output .= $this->get_yui2lib_code();
1156
1157         // all the other linked scripts - there should be as few as possible
1158         if ($this->jsincludes['footer']) {
1159             foreach ($this->jsincludes['footer'] as $url) {
1160                 $output .= html_writer::script('', $url);
1161             }
1162         }
1163
1164         // add all needed strings
1165         if (!empty($this->stringsforjs)) {
1166             $output .= html_writer::script(js_writer::set_variable('M.str', $this->stringsforjs));
1167         }
1168
1169         // add variables
1170         if ($this->jsinitvariables['footer']) {
1171             $js = '';
1172             foreach ($this->jsinitvariables['footer'] as $data) {
1173                 list($var, $value) = $data;
1174                 $js .= js_writer::set_variable($var, $value, true);
1175             }
1176             $output .= html_writer::script($js);
1177         }
1178
1179         $inyuijs = $this->get_javascript_code(false);
1180         $ondomreadyjs = $this->get_javascript_code(true);
1181         $jsinit = $this->get_javascript_init_code();
1182         $handlersjs = $this->get_event_handler_code();
1183
1184         // there is no global Y, make sure it is available in your scope
1185         $js = "YUI(M.yui.loader).use('node', function(Y) {\n{$inyuijs}{$ondomreadyjs}{$jsinit}{$handlersjs}\n});";
1186
1187         $output .= html_writer::script($js);
1188
1189         return $output;
1190     }
1191
1192     /**
1193      * @return boolean Have we already output the code in the <head> tag?
1194      */
1195     public function is_head_done() {
1196         return $this->headdone;
1197     }
1198
1199     /**
1200      * @return boolean Have we already output the code at the start of the <body> tag?
1201      */
1202     public function is_top_of_body_done() {
1203         return $this->topofbodydone;
1204     }
1205 }
1206
1207 /**
1208  * Invalidate all server and client side JS caches.
1209  * @return void
1210  */
1211 function js_reset_all_caches() {
1212     global $CFG;
1213     require_once("$CFG->libdir/filelib.php");
1214
1215     set_config('jsrev', empty($CFG->jsrev) ? 1 : $CFG->jsrev+1);
1216     fulldelete("$CFG->cachedir/js");
1217 }
1218