lib/filterlib.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  * Library functions for managing text filter plugins.
  20  *
  21  * @package    core
  22  * @subpackage filter
  23  * @copyright  1999 onwards Martin Dougiamas  {@link http://moodle.com}
  24  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  25  */
  26
  27 defined('MOODLE_INTERNAL') || die();
  28
  29 /** The states a filter can be in, stored in the filter_active table. */
  30 define('TEXTFILTER_ON', 1);
  31 /** The states a filter can be in, stored in the filter_active table. */
  32 define('TEXTFILTER_INHERIT', 0);
  33 /** The states a filter can be in, stored in the filter_active table. */
  34 define('TEXTFILTER_OFF', -1);
  35 /** The states a filter can be in, stored in the filter_active table. */
  36 define('TEXTFILTER_DISABLED', -9999);
  37
  38 /**
  39  * Define one exclusive separator that we'll use in the temp saved tags
  40  *  keys. It must be something rare enough to avoid having matches with
  41  *  filterobjects. MDL-18165
  42  */
  43 define('TEXTFILTER_EXCL_SEPARATOR', '-%-');
  44
  45
  46 /**
  47  * Class to manage the filtering of strings. It is intended that this class is
  48  * only used by weblib.php. Client code should probably be using the
  49  * format_text and format_string functions.
  50  *
  51  * This class is a singleton.
  52  *
  53  * @package    core
  54  * @subpackage filter
  55  * @copyright  1999 onwards Martin Dougiamas  {@link http://moodle.com}
  56  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  57  */
  58 class filter_manager {
  59     /**
  60      * @var array This list of active filters, by context, for filtering content.
  61      * An array contextid => array of filter objects.
  62      */
  63     protected $textfilters = array();
  64
  65     /**
  66      * @var array This list of active filters, by context, for filtering strings.
  67      * An array contextid => array of filter objects.
  68      */
  69     protected $stringfilters = array();
  70
  71     /** @var array Exploded version of $CFG->stringfilters. */
  72     protected $stringfilternames = array();
  73
  74     /** @var object Holds the singleton instance. */
  75     protected static $singletoninstance;
  76
  77     protected function __construct() {
  78         $this->stringfilternames = filter_get_string_filters();
  79     }
  80
  81     /**
  82      * @return filter_manager the singleton instance.
  83      */
  84     public static function instance() {
  85         global $CFG;
  86         if (is_null(self::$singletoninstance)) {
  87             if (!empty($CFG->perfdebug)) {
  88                 self::$singletoninstance = new performance_measuring_filter_manager();
  89             } else {
  90                 self::$singletoninstance = new self();
  91             }
  92         }
  93         return self::$singletoninstance;
  94     }
  95
  96     /**
  97      * Load all the filters required by this context.
  98      *
  99      * @param object $context
 100      */
 101     protected function load_filters($context) {
 102         $filters = filter_get_active_in_context($context);
 103         $this->textfilters[$context->id] = array();
 104         $this->stringfilters[$context->id] = array();
 105         foreach ($filters as $filtername => $localconfig) {
 106             $filter = $this->make_filter_object($filtername, $context, $localconfig);
 107             if (is_null($filter)) {
 108                 continue;
 109             }
 110             $this->textfilters[$context->id][] = $filter;
 111             if (in_array($filtername, $this->stringfilternames)) {
 112                 $this->stringfilters[$context->id][] = $filter;
 113             }
 114         }
 115     }
 116
 117     /**
 118      * Factory method for creating a filter
 119      *
 120      * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
 121      * @param object $context context object.
 122      * @param array $localconfig array of local configuration variables for this filter.
 123      * @return object moodle_text_filter The filter, or null, if this type of filter is
 124      *      not recognised or could not be created.
 125      */
 126     protected function make_filter_object($filtername, $context, $localconfig) {
 127         global $CFG;
 128         $path = $CFG->dirroot .'/'. $filtername .'/filter.php';
 129         if (!is_readable($path)) {
 130             return null;
 131         }
 132         include_once($path);
 133
 134         $filterclassname = 'filter_' . basename($filtername);
 135         if (class_exists($filterclassname)) {
 136             return new $filterclassname($context, $localconfig);
 137         }
 138
 139         // TODO: deprecated since 2.2, will be out in 2.3, see MDL-29996
 140         $legacyfunctionname = basename($filtername) . '_filter';
 141         if (function_exists($legacyfunctionname)) {
 142             return new legacy_filter($legacyfunctionname, $context, $localconfig);
 143         }
 144
 145         return null;
 146     }
 147
 148     /**
 149      * @todo Document this function
 150      * @param string $text
 151      * @param array $filterchain
 152      * @param array $options options passed to the filters
 153      * @return string $text
 154      */
 155     protected function apply_filter_chain($text, $filterchain, array $options = array()) {
 156         foreach ($filterchain as $filter) {
 157             $text = $filter->filter($text, $options);
 158         }
 159         return $text;
 160     }
 161
 162     /**
 163      * @todo Document this function
 164      * @param object $context
 165      * @return object A text filter
 166      */
 167     protected function get_text_filters($context) {
 168         if (!isset($this->textfilters[$context->id])) {
 169             $this->load_filters($context);
 170         }
 171         return $this->textfilters[$context->id];
 172     }
 173
 174     /**
 175      * @todo Document this function
 176      * @param object $context
 177      * @return object A string filter
 178      */
 179     protected function get_string_filters($context) {
 180         if (!isset($this->stringfilters[$context->id])) {
 181             $this->load_filters($context);
 182         }
 183         return $this->stringfilters[$context->id];
 184     }
 185
 186     /**
 187      * Filter some text
 188      *
 189      * @param string $text The text to filter
 190      * @param object $context
 191      * @param array $options options passed to the filters
 192      * @return string resulting text
 193      */
 194     public function filter_text($text, $context, array $options = array()) {
 195         $text = $this->apply_filter_chain($text, $this->get_text_filters($context), $options);
 196         /// <nolink> tags removed for XHTML compatibility
 197         $text = str_replace(array('<nolink>', '</nolink>'), '', $text);
 198         return $text;
 199     }
 200
 201     /**
 202      * Filter a piece of string
 203      *
 204      * @param string $string The text to filter
 205      * @param object $context
 206      * @return string resulting string
 207      */
 208     public function filter_string($string, $context) {
 209         return $this->apply_filter_chain($string, $this->get_string_filters($context));
 210     }
 211
 212     /**
 213      * @todo Document this function
 214      * @param object $context
 215      * @return object A string filter
 216      */
 217     public function text_filtering_hash($context) {
 218         $filters = $this->get_text_filters($context);
 219         $hashes = array();
 220         foreach ($filters as $filter) {
 221             $hashes[] = $filter->hash();
 222         }
 223         return implode('-', $hashes);
 224     }
 225
 226     /**
 227      * Setup page with filters requirements and other prepare stuff.
 228      *
 229      * This method is used by {@see format_text()} and {@see format_string()}
 230      * in order to allow filters to setup any page requirement (js, css...)
 231      * or perform any action needed to get them prepared before filtering itself
 232      * happens by calling to each every active setup() method.
 233      *
 234      * Note it's executed for each piece of text filtered, so filter implementations
 235      * are responsible of controlling the cardinality of the executions that may
 236      * be different depending of the stuff to prepare.
 237      *
 238      * @param moodle_page $page the page we are going to add requirements to.
 239      * @param context $context the context which contents are going to be filtered.
 240      * @since 2.3
 241      */
 242     public function setup_page_for_filters($page, $context) {
 243         $filters = $this->get_text_filters($context);
 244         foreach ($filters as $filter) {
 245             $filter->setup($page, $context);
 246         }
 247     }
 248 }
 249
 250 /**
 251  * Filter manager subclass that does nothing. Having this simplifies the logic
 252  * of format_text, etc.
 253  *
 254  * @todo Document this class
 255  *
 256  * @package    core
 257  * @subpackage filter
 258  * @copyright  1999 onwards Martin Dougiamas  {@link http://moodle.com}
 259  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 260  */
 261 class null_filter_manager {
 262     /**
 263      * @return string
 264      */
 265     public function filter_text($text, $context, $options) {
 266         return $text;
 267     }
 268
 269     /**
 270      * @return string
 271      */
 272     public function filter_string($string, $context) {
 273         return $string;
 274     }
 275
 276     /**
 277      * @return string
 278      */
 279     public function text_filtering_hash() {
 280         return '';
 281     }
 282 }
 283
 284 /**
 285  * Filter manager subclass that tacks how much work it does.
 286  *
 287  * @todo Document this class
 288  *
 289  * @package    core
 290  * @subpackage filter
 291  * @copyright  1999 onwards Martin Dougiamas  {@link http://moodle.com}
 292  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 293  */
 294 class performance_measuring_filter_manager extends filter_manager {
 295     /** @var int */
 296     protected $filterscreated = 0;
 297     protected $textsfiltered = 0;
 298     protected $stringsfiltered = 0;
 299
 300     /**
 301      * @param string $filtername
 302      * @param object $context
 303      * @param mixed $localconfig
 304      * @return mixed
 305      */
 306     protected function make_filter_object($filtername, $context, $localconfig) {
 307         $this->filterscreated++;
 308         return parent::make_filter_object($filtername, $context, $localconfig);
 309     }
 310
 311     /**
 312      * @param string $text
 313      * @param object $context
 314      * @param array $options options passed to the filters
 315      * @return mixed
 316      */
 317     public function filter_text($text, $context, array $options = array()) {
 318         $this->textsfiltered++;
 319         return parent::filter_text($text, $context, $options);
 320     }
 321
 322     /**
 323      * @param string $string
 324      * @param object $context
 325      * @return mixed
 326      */
 327     public function filter_string($string, $context) {
 328         $this->stringsfiltered++;
 329         return parent::filter_string($string, $context);
 330     }
 331
 332     /**
 333      * @return array
 334      */
 335     public function get_performance_summary() {
 336         return array(array(
 337             'contextswithfilters' => count($this->textfilters),
 338             'filterscreated' => $this->filterscreated,
 339             'textsfiltered' => $this->textsfiltered,
 340             'stringsfiltered' => $this->stringsfiltered,
 341         ), array(
 342             'contextswithfilters' => 'Contexts for which filters were loaded',
 343             'filterscreated' => 'Filters created',
 344             'textsfiltered' => 'Pieces of content filtered',
 345             'stringsfiltered' => 'Strings filtered',
 346         ));
 347     }
 348 }
 349
 350 /**
 351  * Base class for text filters. You just need to override this class and
 352  * implement the filter method.
 353  *
 354  * @package    core
 355  * @subpackage filter
 356  * @copyright  1999 onwards Martin Dougiamas  {@link http://moodle.com}
 357  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 358  */
 359 abstract class moodle_text_filter {
 360     /** @var object The context we are in. */
 361     protected $context;
 362     /** @var array Any local configuration for this filter in this context. */
 363     protected $localconfig;
 364
 365     /**
 366      * Set any context-specific configuration for this filter.
 367      * @param object $context The current course id.
 368      * @param object $context The current context.
 369      * @param array $config Any context-specific configuration for this filter.
 370      */
 371     public function __construct($context, array $localconfig) {
 372         $this->context = $context;
 373         $this->localconfig = $localconfig;
 374     }
 375
 376     /**
 377      * @return string The class name of the current class
 378      */
 379     public function hash() {
 380         return __CLASS__;
 381     }
 382
 383     /**
 384      * Setup page with filter requirements and other prepare stuff.
 385      *
 386      * Override this method if the filter needs to setup page
 387      * requirements or needs other stuff to be executed.
 388      *
 389      * Note this method is invoked from {@see setup_page_for_filters()}
 390      * for each piece of text being filtered, so it is responsible
 391      * for controlling its own execution cardinality.
 392      *
 393      * @param moodle_page $page the page we are going to add requirements to.
 394      * @param context $context the context which contents are going to be filtered.
 395      * @since 2.3
 396      */
 397     public function setup($page, $context) {
 398         // Override me, if needed.
 399     }
 400
 401     /**
 402      * Override this function to actually implement the filtering.
 403      *
 404      * @param $text some HTML content.
 405      * @param array $options options passed to the filters
 406      * @return the HTML content after the filtering has been applied.
 407      */
 408     public abstract function filter($text, array $options = array());
 409 }
 410
 411 /**
 412  * moodle_text_filter implementation that encapsulates an old-style filter that
 413  * only defines a function, not a class.
 414  *
 415  * @deprecated since 2.2, see MDL-29995
 416  * @todo will be out in 2.3, see MDL-29996
 417  * @package    core
 418  * @subpackage filter
 419  * @copyright  1999 onwards Martin Dougiamas  {@link http://moodle.com}
 420  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 421  */
 422 class legacy_filter extends moodle_text_filter {
 423     /** @var string */
 424     protected $filterfunction;
 425     protected $courseid;
 426
 427     /**
 428      * Set any context-specific configuration for this filter.
 429      *
 430      * @param string $filterfunction
 431      * @param object $context The current context.
 432      * @param array $config Any context-specific configuration for this filter.
 433      */
 434     public function __construct($filterfunction, $context, array $localconfig) {
 435         parent::__construct($context, $localconfig);
 436         $this->filterfunction = $filterfunction;
 437         $this->courseid = get_courseid_from_context($this->context);
 438     }
 439
 440     /**
 441      * @param string $text
 442      * @param array $options options - not supported for legacy filters
 443      * @return mixed
 444      */
 445     public function filter($text, array $options = array()) {
 446         if ($this->courseid) {
 447             // old filters are called only when inside courses
 448             return call_user_func($this->filterfunction, $this->courseid, $text);
 449         } else {
 450             return $text;
 451         }
 452     }
 453 }
 454
 455 /**
 456  * This is just a little object to define a phrase and some instructions
 457  * for how to process it.  Filters can create an array of these to pass
 458  * to the filter_phrases function below.
 459  *
 460  * @package    core
 461  * @subpackage filter
 462  * @copyright  1999 onwards Martin Dougiamas  {@link http://moodle.com}
 463  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 464  **/
 465 class filterobject {
 466     /** @var string */
 467     var $phrase;
 468     var $hreftagbegin;
 469     var $hreftagend;
 470     /** @var bool */
 471     var $casesensitive;
 472     var $fullmatch;
 473     /** @var mixed */
 474     var $replacementphrase;
 475     var $work_phrase;
 476     var $work_hreftagbegin;
 477     var $work_hreftagend;
 478     var $work_casesensitive;
 479     var $work_fullmatch;
 480     var $work_replacementphrase;
 481     /** @var bool */
 482     var $work_calculated;
 483
 484     /**
 485      * A constructor just because I like constructing
 486      *
 487      * @param string $phrase
 488      * @param string $hreftagbegin
 489      * @param string $hreftagend
 490      * @param bool $casesensitive
 491      * @param bool $fullmatch
 492      * @param mixed $replacementphrase
 493      */
 494     function filterobject($phrase, $hreftagbegin = '<span class="highlight">',
 495                                    $hreftagend = '</span>',
 496                                    $casesensitive = false,
 497                                    $fullmatch = false,
 498                                    $replacementphrase = NULL) {
 499
 500         $this->phrase           = $phrase;
 501         $this->hreftagbegin     = $hreftagbegin;
 502         $this->hreftagend       = $hreftagend;
 503         $this->casesensitive    = $casesensitive;
 504         $this->fullmatch        = $fullmatch;
 505         $this->replacementphrase= $replacementphrase;
 506         $this->work_calculated  = false;
 507
 508     }
 509 }
 510
 511 /**
 512  * Look up the name of this filter in the most appropriate location.
 513  * If $filterlocation = 'mod' then does get_string('filtername', $filter);
 514  * else if $filterlocation = 'filter' then does get_string('filtername', 'filter_' . $filter);
 515  * with a fallback to get_string('filtername', $filter) for backwards compatibility.
 516  * These are the only two options supported at the moment.
 517  *
 518  * @param string $filter the folder name where the filter lives.
 519  * @return string the human-readable name for this filter.
 520  */
 521 function filter_get_name($filter) {
 522     // TODO: should we be using pluginname here instead? , see MDL-29998
 523     list($type, $filter) = explode('/', $filter);
 524     switch ($type) {
 525         case 'filter':
 526             $strfiltername = get_string('filtername', 'filter_' . $filter);
 527             if (substr($strfiltername, 0, 2) != '[[') {
 528                 // found a valid string.
 529                 return $strfiltername;
 530             }
 531             // Fall through to try the legacy location.
 532
 533         // TODO: deprecated since 2.2, will be out in 2.3, see MDL-29996
 534         case 'mod':
 535             $strfiltername = get_string('filtername', $filter);
 536             if (substr($strfiltername, 0, 2) == '[[') {
 537                 $strfiltername .= ' (' . $type . '/' . $filter . ')';
 538             }
 539             return $strfiltername;
 540
 541         default:
 542             throw new coding_exception('Unknown filter type ' . $type);
 543     }
 544 }
 545
 546 /**
 547  * Get the names of all the filters installed in this Moodle.
 548  *
 549  * @global object
 550  * @return array path => filter name from the appropriate lang file. e.g.
 551  * array('mod/glossary' => 'Glossary Auto-linking', 'filter/tex' => 'TeX Notation');
 552  * sorted in alphabetical order of name.
 553  */
 554 function filter_get_all_installed() {
 555     global $CFG;
 556     $filternames = array();
 557     // TODO: deprecated since 2.2, will be out in 2.3, see MDL-29996
 558     $filterlocations = array('mod', 'filter');
 559     foreach ($filterlocations as $filterlocation) {
 560         // TODO: move get_list_of_plugins() to get_plugin_list()
 561         $filters = get_list_of_plugins($filterlocation);
 562         foreach ($filters as $filter) {
 563             // MDL-29994 - Ignore mod/data and mod/glossary filters forever, this will be out in 2.3
 564             if ($filterlocation == 'mod' && ($filter == 'data' || $filter == 'glossary')) {
 565                 continue;
 566             }
 567             $path = $filterlocation . '/' . $filter;
 568             if (is_readable($CFG->dirroot . '/' . $path . '/filter.php')) {
 569                 $strfiltername = filter_get_name($path);
 570                 $filternames[$path] = $strfiltername;
 571             }
 572         }
 573     }
 574     collatorlib::asort($filternames);
 575     return $filternames;
 576 }
 577
 578 /**
 579  * Set the global activated state for a text filter.
 580  *
 581  * @global object
 582  * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
 583  * @param integer $state One of the values TEXTFILTER_ON, TEXTFILTER_OFF or TEXTFILTER_DISABLED.
 584  * @param integer $sortorder (optional) a position in the sortorder to place this filter.
 585  *      If not given defaults to:
 586  *      No change in order if we are updating an existing record, and not changing to or from TEXTFILTER_DISABLED.
 587  *      Just after the last currently active filter when adding an unknown filter
 588  *          in state TEXTFILTER_ON or TEXTFILTER_OFF, or enabling/disabling an existing filter.
 589  *      Just after the very last filter when adding an unknown filter in state TEXTFILTER_DISABLED
 590  */
 591 function filter_set_global_state($filter, $state, $sortorder = false) {
 592     global $DB;
 593
 594     // Check requested state is valid.
 595     if (!in_array($state, array(TEXTFILTER_ON, TEXTFILTER_OFF, TEXTFILTER_DISABLED))) {
 596         throw new coding_exception("Illegal option '$state' passed to filter_set_global_state. " .
 597                 "Must be one of TEXTFILTER_ON, TEXTFILTER_OFF or TEXTFILTER_DISABLED.");
 598     }
 599
 600     // Check sortorder is valid.
 601     if ($sortorder !== false) {
 602         if ($sortorder < 1 || $sortorder > $DB->get_field('filter_active', 'MAX(sortorder)', array()) + 1) {
 603             throw new coding_exception("Invalid sort order passed to filter_set_global_state.");
 604         }
 605     }
 606
 607     // See if there is an existing record.
 608     $syscontext = context_system::instance();
 609     $rec = $DB->get_record('filter_active', array('filter' => $filter, 'contextid' => $syscontext->id));
 610     if (empty($rec)) {
 611         $insert = true;
 612         $rec = new stdClass;
 613         $rec->filter = $filter;
 614         $rec->contextid = $syscontext->id;
 615     } else {
 616         $insert = false;
 617         if ($sortorder === false && !($rec->active == TEXTFILTER_DISABLED xor $state == TEXTFILTER_DISABLED)) {
 618             $sortorder = $rec->sortorder;
 619         }
 620     }
 621
 622     // Automatic sort order.
 623     if ($sortorder === false) {
 624         if ($state == TEXTFILTER_DISABLED && $insert) {
 625             $prevmaxsortorder = $DB->get_field('filter_active', 'MAX(sortorder)', array());
 626         } else {
 627             $prevmaxsortorder = $DB->get_field_select('filter_active', 'MAX(sortorder)', 'active <> ?', array(TEXTFILTER_DISABLED));
 628         }
 629         if (empty($prevmaxsortorder)) {
 630             $sortorder = 1;
 631         } else {
 632             $sortorder = $prevmaxsortorder + 1;
 633             if (!$insert && $state == TEXTFILTER_DISABLED) {
 634                 $sortorder = $prevmaxsortorder;
 635             }
 636         }
 637     }
 638
 639     // Move any existing records out of the way of the sortorder.
 640     if ($insert) {
 641         $DB->execute('UPDATE {filter_active} SET sortorder = sortorder + 1 WHERE sortorder >= ?', array($sortorder));
 642     } else if ($sortorder != $rec->sortorder) {
 643         $sparesortorder = $DB->get_field('filter_active', 'MIN(sortorder)', array()) - 1;
 644         $DB->set_field('filter_active', 'sortorder', $sparesortorder, array('filter' => $filter, 'contextid' => $syscontext->id));
 645         if ($sortorder < $rec->sortorder) {
 646             $DB->execute('UPDATE {filter_active} SET sortorder = sortorder + 1 WHERE sortorder >= ? AND sortorder < ?',
 647                     array($sortorder, $rec->sortorder));
 648         } else if ($sortorder > $rec->sortorder) {
 649             $DB->execute('UPDATE {filter_active} SET sortorder = sortorder - 1 WHERE sortorder <= ? AND sortorder > ?',
 650                     array($sortorder, $rec->sortorder));
 651         }
 652     }
 653
 654     // Insert/update the new record.
 655     $rec->active = $state;
 656     $rec->sortorder = $sortorder;
 657     if ($insert) {
 658         $DB->insert_record('filter_active', $rec);
 659     } else {
 660         $DB->update_record('filter_active', $rec);
 661     }
 662 }
 663
 664 /**
 665  * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
 666  * @return boolean is this filter allowed to be used on this site. That is, the
 667  *      admin has set the global 'active' setting to On, or Off, but available.
 668  */
 669 function filter_is_enabled($filter) {
 670     return array_key_exists($filter, filter_get_globally_enabled());
 671 }
 672
 673 /**
 674  * Return a list of all the filters that may be in use somewhere.
 675  *
 676  * @staticvar array $enabledfilters
 677  * @return array where the keys and values are both the filter name, like 'filter/tex'.
 678  */
 679 function filter_get_globally_enabled() {
 680     static $enabledfilters = null;
 681     if (is_null($enabledfilters)) {
 682         $filters = filter_get_global_states();
 683         $enabledfilters = array();
 684         foreach ($filters as $filter => $filerinfo) {
 685             if ($filerinfo->active != TEXTFILTER_DISABLED) {
 686                 $enabledfilters[$filter] = $filter;
 687             }
 688         }
 689     }
 690     return $enabledfilters;
 691 }
 692
 693 /**
 694  * Return the names of the filters that should also be applied to strings
 695  * (when they are enabled).
 696  *
 697  * @global object
 698  * @return array where the keys and values are both the filter name, like 'filter/tex'.
 699  */
 700 function filter_get_string_filters() {
 701     global $CFG;
 702     $stringfilters = array();
 703     if (!empty($CFG->filterall) && !empty($CFG->stringfilters)) {
 704         $stringfilters = explode(',', $CFG->stringfilters);
 705         $stringfilters = array_combine($stringfilters, $stringfilters);
 706     }
 707     return $stringfilters;
 708 }
 709
 710 /**
 711  * Sets whether a particular active filter should be applied to all strings by
 712  * format_string, or just used by format_text.
 713  *
 714  * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
 715  * @param boolean $applytostrings if true, this filter will apply to format_string
 716  *      and format_text, when it is enabled.
 717  */
 718 function filter_set_applies_to_strings($filter, $applytostrings) {
 719     $stringfilters = filter_get_string_filters();
 720     $numstringfilters = count($stringfilters);
 721     if ($applytostrings) {
 722         $stringfilters[$filter] = $filter;
 723     } else {
 724         unset($stringfilters[$filter]);
 725     }
 726     if (count($stringfilters) != $numstringfilters) {
 727         set_config('stringfilters', implode(',', $stringfilters));
 728         set_config('filterall', !empty($stringfilters));
 729     }
 730 }
 731
 732 /**
 733  * Set the local activated state for a text filter.
 734  *
 735  * @global object
 736  * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
 737  * @param integer $contextid The id of the context to get the local config for.
 738  * @param integer $state One of the values TEXTFILTER_ON, TEXTFILTER_OFF or TEXTFILTER_INHERIT.
 739  * @return void
 740  */
 741 function filter_set_local_state($filter, $contextid, $state) {
 742     global $DB;
 743
 744     // Check requested state is valid.
 745     if (!in_array($state, array(TEXTFILTER_ON, TEXTFILTER_OFF, TEXTFILTER_INHERIT))) {
 746         throw new coding_exception("Illegal option '$state' passed to filter_set_local_state. " .
 747                 "Must be one of TEXTFILTER_ON, TEXTFILTER_OFF or TEXTFILTER_INHERIT.");
 748     }
 749
 750     if ($contextid == context_system::instance()->id) {
 751         throw new coding_exception('You cannot use filter_set_local_state ' .
 752                 'with $contextid equal to the system context id.');
 753     }
 754
 755     if ($state == TEXTFILTER_INHERIT) {
 756         $DB->delete_records('filter_active', array('filter' => $filter, 'contextid' => $contextid));
 757         return;
 758     }
 759
 760     $rec = $DB->get_record('filter_active', array('filter' => $filter, 'contextid' => $contextid));
 761     $insert = false;
 762     if (empty($rec)) {
 763         $insert = true;
 764         $rec = new stdClass;
 765         $rec->filter = $filter;
 766         $rec->contextid = $contextid;
 767     }
 768
 769     $rec->active = $state;
 770
 771     if ($insert) {
 772         $DB->insert_record('filter_active', $rec);
 773     } else {
 774         $DB->update_record('filter_active', $rec);
 775     }
 776 }
 777
 778 /**
 779  * Set a particular local config variable for a filter in a context.
 780  *
 781  * @global object
 782  * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
 783  * @param integer $contextid The id of the context to get the local config for.
 784  * @param string $name the setting name.
 785  * @param string $value the corresponding value.
 786  */
 787 function filter_set_local_config($filter, $contextid, $name, $value) {
 788     global $DB;
 789     $rec = $DB->get_record('filter_config', array('filter' => $filter, 'contextid' => $contextid, 'name' => $name));
 790     $insert = false;
 791     if (empty($rec)) {
 792         $insert = true;
 793         $rec = new stdClass;
 794         $rec->filter = $filter;
 795         $rec->contextid = $contextid;
 796         $rec->name = $name;
 797     }
 798
 799     $rec->value = $value;
 800
 801     if ($insert) {
 802         $DB->insert_record('filter_config', $rec);
 803     } else {
 804         $DB->update_record('filter_config', $rec);
 805     }
 806 }
 807
 808 /**
 809  * Remove a particular local config variable for a filter in a context.
 810  *
 811  * @global object
 812  * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
 813  * @param integer $contextid The id of the context to get the local config for.
 814  * @param string $name the setting name.
 815  */
 816 function filter_unset_local_config($filter, $contextid, $name) {
 817     global $DB;
 818     $DB->delete_records('filter_config', array('filter' => $filter, 'contextid' => $contextid, 'name' => $name));
 819 }
 820
 821 /**
 822  * Get local config variables for a filter in a context. Normally (when your
 823  * filter is running) you don't need to call this, becuase the config is fetched
 824  * for you automatically. You only need this, for example, when you are getting
 825  * the config so you can show the user an editing from.
 826  *
 827  * @global object
 828  * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
 829  * @param integer $contextid The ID of the context to get the local config for.
 830  * @return array of name => value pairs.
 831  */
 832 function filter_get_local_config($filter, $contextid) {
 833     global $DB;
 834     return $DB->get_records_menu('filter_config', array('filter' => $filter, 'contextid' => $contextid), '', 'name,value');
 835 }
 836
 837 /**
 838  * This function is for use by backup. Gets all the filter information specific
 839  * to one context.
 840  *
 841  * @global object
 842  * @param int $contextid
 843  * @return array Array with two elements. The first element is an array of objects with
 844  *      fields filter and active. These come from the filter_active table. The
 845  *      second element is an array of objects with fields filter, name and value
 846  *      from the filter_config table.
 847  */
 848 function filter_get_all_local_settings($contextid) {
 849     global $DB;
 850     $context = context_system::instance();
 851     return array(
 852         $DB->get_records('filter_active', array('contextid' => $contextid), 'filter', 'filter,active'),
 853         $DB->get_records('filter_config', array('contextid' => $contextid), 'filter,name', 'filter,name,value'),
 854     );
 855 }
 856
 857 /**
 858  * Get the list of active filters, in the order that they should be used
 859  * for a particular context, along with any local configuration variables.
 860  *
 861  * @global object
 862  * @param object $context a context
 863  * @return array an array where the keys are the filter names, for example
 864  *      'filter/tex' or 'mod/glossary' and the values are any local
 865  *      configuration for that filter, as an array of name => value pairs
 866  *      from the filter_config table. In a lot of cases, this will be an
 867  *      empty array. So, an example return value for this function might be
 868  *      array('filter/tex' => array(), 'mod/glossary' => array('glossaryid', 123))
 869  */
 870 function filter_get_active_in_context($context) {
 871     global $DB, $FILTERLIB_PRIVATE;
 872
 873     if (!isset($FILTERLIB_PRIVATE)) {
 874         $FILTERLIB_PRIVATE = new stdClass();
 875     }
 876
 877     // Use cache (this is a within-request cache only) if available. See
 878     // function filter_preload_activities.
 879     if (isset($FILTERLIB_PRIVATE->active) &&
 880             array_key_exists($context->id, $FILTERLIB_PRIVATE->active)) {
 881         return $FILTERLIB_PRIVATE->active[$context->id];
 882     }
 883
 884     $contextids = str_replace('/', ',', trim($context->path, '/'));
 885
 886     // The following SQL is tricky. It is explained on
 887     // http://docs.moodle.org/dev/Filter_enable/disable_by_context
 888     $sql = "SELECT active.filter, fc.name, fc.value
 889          FROM (SELECT f.filter, MAX(f.sortorder) AS sortorder
 890              FROM {filter_active} f
 891              JOIN {context} ctx ON f.contextid = ctx.id
 892              WHERE ctx.id IN ($contextids)
 893              GROUP BY filter
 894              HAVING MAX(f.active * " . $DB->sql_cast_2signed('ctx.depth') .
 895                     ") > -MIN(f.active * " . $DB->sql_cast_2signed('ctx.depth') . ")
 896          ) active
 897          LEFT JOIN {filter_config} fc ON fc.filter = active.filter AND fc.contextid = $context->id
 898          ORDER BY active.sortorder";
 899     //TODO: remove sql_cast_2signed() once we do not support upgrade from Moodle 2.2
 900     $rs = $DB->get_recordset_sql($sql);
 901
 902     // Masssage the data into the specified format to return.
 903     $filters = array();
 904     foreach ($rs as $row) {
 905         if (!isset($filters[$row->filter])) {
 906             $filters[$row->filter] = array();
 907         }
 908         if (!is_null($row->name)) {
 909             $filters[$row->filter][$row->name] = $row->value;
 910         }
 911     }
 912
 913     $rs->close();
 914
 915     return $filters;
 916 }
 917
 918 /**
 919  * Preloads the list of active filters for all activities (modules) on the course
 920  * using two database queries.
 921  * @param course_modinfo $modinfo Course object from get_fast_modinfo
 922  */
 923 function filter_preload_activities(course_modinfo $modinfo) {
 924     global $DB, $FILTERLIB_PRIVATE;
 925
 926     if (!isset($FILTERLIB_PRIVATE)) {
 927         $FILTERLIB_PRIVATE = new stdClass();
 928     }
 929
 930     // Don't repeat preload
 931     if (!isset($FILTERLIB_PRIVATE->preloaded)) {
 932         $FILTERLIB_PRIVATE->preloaded = array();
 933     }
 934     if (!empty($FILTERLIB_PRIVATE->preloaded[$modinfo->get_course_id()])) {
 935         return;
 936     }
 937     $FILTERLIB_PRIVATE->preloaded[$modinfo->get_course_id()] = true;
 938
 939     // Get contexts for all CMs
 940     $cmcontexts = array();
 941     $cmcontextids = array();
 942     foreach ($modinfo->get_cms() as $cm) {
 943         $modulecontext = context_module::instance($cm->id);
 944         $cmcontextids[] = $modulecontext->id;
 945         $cmcontexts[] = $modulecontext;
 946     }
 947
 948     // Get course context and all other parents...
 949     $coursecontext = context_course::instance($modinfo->get_course_id());
 950     $parentcontextids = explode('/', substr($coursecontext->path, 1));
 951     $allcontextids = array_merge($cmcontextids, $parentcontextids);
 952
 953     // Get all filter_active rows relating to all these contexts
 954     list ($sql, $params) = $DB->get_in_or_equal($allcontextids);
 955     $filteractives = $DB->get_records_select('filter_active', "contextid $sql", $params);
 956
 957     // Get all filter_config only for the cm contexts
 958     list ($sql, $params) = $DB->get_in_or_equal($cmcontextids);
 959     $filterconfigs = $DB->get_records_select('filter_config', "contextid $sql", $params);
 960
 961     // Note: I was a bit surprised that filter_config only works for the
 962     // most specific context (i.e. it does not need to be checked for course
 963     // context if we only care about CMs) however basede on code in
 964     // filter_get_active_in_context, this does seem to be correct.
 965
 966     // Build course default active list. Initially this will be an array of
 967     // filter name => active score (where an active score >0 means it's active)
 968     $courseactive = array();
 969
 970     // Also build list of filter_active rows below course level, by contextid
 971     $remainingactives = array();
 972
 973     // Array lists filters that are banned at top level
 974     $banned = array();
 975
 976     // Add any active filters in parent contexts to the array
 977     foreach ($filteractives as $row) {
 978         $depth = array_search($row->contextid, $parentcontextids);
 979         if ($depth !== false) {
 980             // Find entry
 981             if (!array_key_exists($row->filter, $courseactive)) {
 982                 $courseactive[$row->filter] = 0;
 983             }
 984             // This maths copes with reading rows in any order. Turning on/off
 985             // at site level counts 1, at next level down 4, at next level 9,
 986             // then 16, etc. This means the deepest level always wins, except
 987             // against the -9999 at top level.
 988             $courseactive[$row->filter] +=
 989                 ($depth + 1) * ($depth + 1) * $row->active;
 990
 991             if ($row->active == TEXTFILTER_DISABLED) {
 992                 $banned[$row->filter] = true;
 993             }
 994         } else {
 995             // Build list of other rows indexed by contextid
 996             if (!array_key_exists($row->contextid, $remainingactives)) {
 997                 $remainingactives[$row->contextid] = array();
 998             }
 999             $remainingactives[$row->contextid][] = $row;
1000         }
1001     }
1002
1003     // Chuck away the ones that aren't active
1004     foreach ($courseactive as $filter=>$score) {
1005         if ($score <= 0) {
1006             unset($courseactive[$filter]);
1007         } else {
1008             $courseactive[$filter] = array();
1009         }
1010     }
1011
1012     // Loop through the contexts to reconstruct filter_active lists for each
1013     // cm on the course
1014     if (!isset($FILTERLIB_PRIVATE->active)) {
1015         $FILTERLIB_PRIVATE->active = array();
1016     }
1017     foreach ($cmcontextids as $contextid) {
1018         // Copy course list
1019         $FILTERLIB_PRIVATE->active[$contextid] = $courseactive;
1020
1021         // Are there any changes to the active list?
1022         if (array_key_exists($contextid, $remainingactives)) {
1023             foreach ($remainingactives[$contextid] as $row) {
1024                 if ($row->active > 0 && empty($banned[$row->filter])) {
1025                     // If it's marked active for specific context, add entry
1026                     // (doesn't matter if one exists already)
1027                     $FILTERLIB_PRIVATE->active[$contextid][$row->filter] = array();
1028                 } else {
1029                     // If it's marked inactive, remove entry (doesn't matter
1030                     // if it doesn't exist)
1031                     unset($FILTERLIB_PRIVATE->active[$contextid][$row->filter]);
1032                 }
1033             }
1034         }
1035     }
1036
1037     // Process all config rows to add config data to these entries
1038     foreach ($filterconfigs as $row) {
1039         if (isset($FILTERLIB_PRIVATE->active[$row->contextid][$row->filter])) {
1040             $FILTERLIB_PRIVATE->active[$row->contextid][$row->filter][$row->name] = $row->value;
1041         }
1042     }
1043 }
1044
1045 /**
1046  * List all of the filters that are available in this context, and what the
1047  * local and inherited states of that filter are.
1048  *
1049  * @global object
1050  * @param object $context a context that is not the system context.
1051  * @return array an array with filter names, for example 'filter/tex' or
1052  *      'mod/glossary' as keys. and and the values are objects with fields:
1053  *      ->filter filter name, same as the key.
1054  *      ->localstate TEXTFILTER_ON/OFF/INHERIT
1055  *      ->inheritedstate TEXTFILTER_ON/OFF - the state that will be used if localstate is set to TEXTFILTER_INHERIT.
1056  */
1057 function filter_get_available_in_context($context) {
1058     global $DB;
1059
1060     // The complex logic is working out the active state in the parent context,
1061     // so strip the current context from the list.
1062     $contextids = explode('/', trim($context->path, '/'));
1063     array_pop($contextids);
1064     $contextids = implode(',', $contextids);
1065     if (empty($contextids)) {
1066         throw new coding_exception('filter_get_available_in_context cannot be called with the system context.');
1067     }
1068
1069     // The following SQL is tricky, in the same way at the SQL in filter_get_active_in_context.
1070     $sql = "SELECT parent_states.filter,
1071                 CASE WHEN fa.active IS NULL THEN " . TEXTFILTER_INHERIT . "
1072                 ELSE fa.active END AS localstate,
1073              parent_states.inheritedstate
1074          FROM (SELECT f.filter, MAX(f.sortorder) AS sortorder,
1075                     CASE WHEN MAX(f.active * " . $DB->sql_cast_2signed('ctx.depth') .
1076                             ") > -MIN(f.active * " . $DB->sql_cast_2signed('ctx.depth') . ") THEN " . TEXTFILTER_ON . "
1077                     ELSE " . TEXTFILTER_OFF . " END AS inheritedstate
1078              FROM {filter_active} f
1079              JOIN {context} ctx ON f.contextid = ctx.id
1080              WHERE ctx.id IN ($contextids)
1081              GROUP BY f.filter
1082              HAVING MIN(f.active) > " . TEXTFILTER_DISABLED . "
1083          ) parent_states
1084          LEFT JOIN {filter_active} fa ON fa.filter = parent_states.filter AND fa.contextid = $context->id
1085          ORDER BY parent_states.sortorder";
1086     return $DB->get_records_sql($sql);
1087 }
1088
1089 /**
1090  * This function is for use by the filter administration page.
1091  *
1092  * @global object
1093  * @return array 'filtername' => object with fields 'filter' (=filtername), 'active' and 'sortorder'
1094  */
1095 function filter_get_global_states() {
1096     global $DB;
1097     $context = context_system::instance();
1098     return $DB->get_records('filter_active', array('contextid' => $context->id), 'sortorder', 'filter,active,sortorder');
1099 }
1100
1101 /**
1102  * Delete all the data in the database relating to a filter, prior to deleting it.
1103  *
1104  * @global object
1105  * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
1106  */
1107 function filter_delete_all_for_filter($filter) {
1108     global $DB;
1109     if (substr($filter, 0, 7) == 'filter/') {
1110         unset_all_config_for_plugin('filter_' . basename($filter));
1111     }
1112     $DB->delete_records('filter_active', array('filter' => $filter));
1113     $DB->delete_records('filter_config', array('filter' => $filter));
1114 }
1115
1116 /**
1117  * Delete all the data in the database relating to a context, used when contexts are deleted.
1118  *
1119  * @param integer $contextid The id of the context being deleted.
1120  */
1121 function filter_delete_all_for_context($contextid) {
1122     global $DB;
1123     $DB->delete_records('filter_active', array('contextid' => $contextid));
1124     $DB->delete_records('filter_config', array('contextid' => $contextid));
1125 }
1126
1127 /**
1128  * Does this filter have a global settings page in the admin tree?
1129  * (The settings page for a filter must be called, for example,
1130  * filtersettingfiltertex or filtersettingmodglossay.)
1131  *
1132  * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
1133  * @return boolean Whether there should be a 'Settings' link on the config page.
1134  */
1135 function filter_has_global_settings($filter) {
1136     global $CFG;
1137     $settingspath = $CFG->dirroot . '/' . $filter . '/filtersettings.php';
1138     return is_readable($settingspath);
1139 }
1140
1141 /**
1142  * Does this filter have local (per-context) settings?
1143  *
1144  * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
1145  * @return boolean Whether there should be a 'Settings' link on the manage filters in context page.
1146  */
1147 function filter_has_local_settings($filter) {
1148     global $CFG;
1149     $settingspath = $CFG->dirroot . '/' . $filter . '/filterlocalsettings.php';
1150     return is_readable($settingspath);
1151 }
1152
1153 /**
1154  * Certain types of context (block and user) may not have local filter settings.
1155  * the function checks a context to see whether it may have local config.
1156  *
1157  * @param object $context a context.
1158  * @return boolean whether this context may have local filter settings.
1159  */
1160 function filter_context_may_have_filter_settings($context) {
1161     return $context->contextlevel != CONTEXT_BLOCK && $context->contextlevel != CONTEXT_USER;
1162 }
1163
1164 /**
1165  * Process phrases intelligently found within a HTML text (such as adding links)
1166  *
1167  * @staticvar array $usedpharses
1168  * @param string $text             the text that we are filtering
1169  * @param array $link_array       an array of filterobjects
1170  * @param array $ignoretagsopen   an array of opening tags that we should ignore while filtering
1171  * @param array $ignoretagsclose  an array of corresponding closing tags
1172  * @param bool $overridedefaultignore True to only use tags provided by arguments
1173  * @return string
1174  **/
1175 function filter_phrases($text, &$link_array, $ignoretagsopen=NULL, $ignoretagsclose=NULL,
1176         $overridedefaultignore=false) {
1177
1178     global $CFG;
1179
1180     static $usedphrases;
1181
1182     $ignoretags = array();  //To store all the enclosig tags to be completely ignored
1183     $tags = array();        //To store all the simple tags to be ignored
1184
1185     if (!$overridedefaultignore) {
1186         // A list of open/close tags that we should not replace within
1187         // Extended to include <script>, <textarea>, <select> and <a> tags
1188         // Regular expression allows tags with or without attributes
1189         $filterignoretagsopen  = array('<head>' , '<nolink>' , '<span class="nolink">',
1190                 '<script(\s[^>]*?)?>', '<textarea(\s[^>]*?)?>',
1191                 '<select(\s[^>]*?)?>', '<a(\s[^>]*?)?>');
1192         $filterignoretagsclose = array('</head>', '</nolink>', '</span>',
1193                  '</script>', '</textarea>', '</select>','</a>');
1194     } else {
1195         // Set an empty default list
1196         $filterignoretagsopen = array();
1197         $filterignoretagsclose = array();
1198     }
1199
1200     // Add the user defined ignore tags to the default list
1201     if ( is_array($ignoretagsopen) ) {
1202         foreach ($ignoretagsopen as $open) {
1203             $filterignoretagsopen[] = $open;
1204         }
1205         foreach ($ignoretagsclose as $close) {
1206             $filterignoretagsclose[] = $close;
1207         }
1208     }
1209
1210 /// Invalid prefixes and suffixes for the fullmatch searches
1211 /// Every "word" character, but the underscore, is a invalid suffix or prefix.
1212 /// (nice to use this because it includes national characters (accents...) as word characters.
1213     $filterinvalidprefixes = '([^\W_])';
1214     $filterinvalidsuffixes = '([^\W_])';
1215
1216     //// Double up some magic chars to avoid "accidental matches"
1217     $text = preg_replace('/([#*%])/','\1\1',$text);
1218
1219
1220 ////Remove everything enclosed by the ignore tags from $text
1221     filter_save_ignore_tags($text,$filterignoretagsopen,$filterignoretagsclose,$ignoretags);
1222
1223 /// Remove tags from $text
1224     filter_save_tags($text,$tags);
1225
1226 /// Time to cycle through each phrase to be linked
1227     $size = sizeof($link_array);
1228     for ($n=0; $n < $size; $n++) {
1229         $linkobject =& $link_array[$n];
1230
1231     /// Set some defaults if certain properties are missing
1232     /// Properties may be missing if the filterobject class has not been used to construct the object
1233         if (empty($linkobject->phrase)) {
1234             continue;
1235         }
1236
1237     /// Avoid integers < 1000 to be linked. See bug 1446.
1238         $intcurrent = intval($linkobject->phrase);
1239         if (!empty($intcurrent) && strval($intcurrent) == $linkobject->phrase && $intcurrent < 1000) {
1240             continue;
1241         }
1242
1243     /// All this work has to be done ONLY it it hasn't been done before
1244     if (!$linkobject->work_calculated) {
1245             if (!isset($linkobject->hreftagbegin) or !isset($linkobject->hreftagend)) {
1246                 $linkobject->work_hreftagbegin = '<span class="highlight"';
1247                 $linkobject->work_hreftagend   = '</span>';
1248             } else {
1249                 $linkobject->work_hreftagbegin = $linkobject->hreftagbegin;
1250                 $linkobject->work_hreftagend   = $linkobject->hreftagend;
1251             }
1252
1253         /// Double up chars to protect true duplicates
1254         /// be cleared up before returning to the user.
1255             $linkobject->work_hreftagbegin = preg_replace('/([#*%])/','\1\1',$linkobject->work_hreftagbegin);
1256
1257             if (empty($linkobject->casesensitive)) {
1258                 $linkobject->work_casesensitive = false;
1259             } else {
1260                 $linkobject->work_casesensitive = true;
1261             }
1262             if (empty($linkobject->fullmatch)) {
1263                 $linkobject->work_fullmatch = false;
1264             } else {
1265                 $linkobject->work_fullmatch = true;
1266             }
1267
1268         /// Strip tags out of the phrase
1269             $linkobject->work_phrase = strip_tags($linkobject->phrase);
1270
1271         /// Double up chars that might cause a false match -- the duplicates will
1272         /// be cleared up before returning to the user.
1273             $linkobject->work_phrase = preg_replace('/([#*%])/','\1\1',$linkobject->work_phrase);
1274
1275         /// Set the replacement phrase properly
1276             if ($linkobject->replacementphrase) {    //We have specified a replacement phrase
1277             /// Strip tags
1278                 $linkobject->work_replacementphrase = strip_tags($linkobject->replacementphrase);
1279             } else {                                 //The replacement is the original phrase as matched below
1280                 $linkobject->work_replacementphrase = '$1';
1281             }
1282
1283         /// Quote any regular expression characters and the delimiter in the work phrase to be searched
1284             $linkobject->work_phrase = preg_quote($linkobject->work_phrase, '/');
1285
1286         /// Work calculated
1287             $linkobject->work_calculated = true;
1288
1289         }
1290
1291     /// If $CFG->filtermatchoneperpage, avoid previously (request) linked phrases
1292         if (!empty($CFG->filtermatchoneperpage)) {
1293             if (!empty($usedphrases) && in_array($linkobject->work_phrase,$usedphrases)) {
1294                 continue;
1295             }
1296         }
1297
1298     /// Regular expression modifiers
1299         $modifiers = ($linkobject->work_casesensitive) ? 's' : 'isu'; // works in unicode mode!
1300
1301     /// Do we need to do a fullmatch?
1302     /// If yes then go through and remove any non full matching entries
1303         if ($linkobject->work_fullmatch) {
1304             $notfullmatches = array();
1305             $regexp = '/'.$filterinvalidprefixes.'('.$linkobject->work_phrase.')|('.$linkobject->work_phrase.')'.$filterinvalidsuffixes.'/'.$modifiers;
1306
1307             preg_match_all($regexp,$text,$list_of_notfullmatches);
1308
1309             if ($list_of_notfullmatches) {
1310                 foreach (array_unique($list_of_notfullmatches[0]) as $key=>$value) {
1311                     $notfullmatches['<*'.$key.'*>'] = $value;
1312                 }
1313                 if (!empty($notfullmatches)) {
1314                     $text = str_replace($notfullmatches,array_keys($notfullmatches),$text);
1315                 }
1316             }
1317         }
1318
1319     /// Finally we do our highlighting
1320         if (!empty($CFG->filtermatchonepertext) || !empty($CFG->filtermatchoneperpage)) {
1321             $resulttext = preg_replace('/('.$linkobject->work_phrase.')/'.$modifiers,
1322                                       $linkobject->work_hreftagbegin.
1323                                       $linkobject->work_replacementphrase.
1324                                       $linkobject->work_hreftagend, $text, 1);
1325         } else {
1326             $resulttext = preg_replace('/('.$linkobject->work_phrase.')/'.$modifiers,
1327                                       $linkobject->work_hreftagbegin.
1328                                       $linkobject->work_replacementphrase.
1329                                       $linkobject->work_hreftagend, $text);
1330         }
1331
1332
1333     /// If the text has changed we have to look for links again
1334         if ($resulttext != $text) {
1335         /// Set $text to $resulttext
1336             $text = $resulttext;
1337         /// Remove everything enclosed by the ignore tags from $text
1338             filter_save_ignore_tags($text,$filterignoretagsopen,$filterignoretagsclose,$ignoretags);
1339         /// Remove tags from $text
1340             filter_save_tags($text,$tags);
1341         /// If $CFG->filtermatchoneperpage, save linked phrases to request
1342             if (!empty($CFG->filtermatchoneperpage)) {
1343                 $usedphrases[] = $linkobject->work_phrase;
1344             }
1345         }
1346
1347
1348     /// Replace the not full matches before cycling to next link object
1349         if (!empty($notfullmatches)) {
1350             $text = str_replace(array_keys($notfullmatches),$notfullmatches,$text);
1351             unset($notfullmatches);
1352         }
1353     }
1354
1355 /// Rebuild the text with all the excluded areas
1356
1357     if (!empty($tags)) {
1358         $text = str_replace(array_keys($tags), $tags, $text);
1359     }
1360
1361     if (!empty($ignoretags)) {
1362         $ignoretags = array_reverse($ignoretags); /// Reversed so "progressive" str_replace() will solve some nesting problems.
1363         $text = str_replace(array_keys($ignoretags),$ignoretags,$text);
1364     }
1365
1366     //// Remove the protective doubleups
1367     $text =  preg_replace('/([#*%])(\1)/','\1',$text);
1368
1369 /// Add missing javascript for popus
1370     $text = filter_add_javascript($text);
1371
1372
1373     return $text;
1374 }
1375
1376 /**
1377  * @todo Document this function
1378  * @param array $linkarray
1379  * @return array
1380  */
1381 function filter_remove_duplicates($linkarray) {
1382
1383     $concepts  = array(); // keep a record of concepts as we cycle through
1384     $lconcepts = array(); // a lower case version for case insensitive
1385
1386     $cleanlinks = array();
1387
1388     foreach ($linkarray as $key=>$filterobject) {
1389         if ($filterobject->casesensitive) {
1390             $exists = in_array($filterobject->phrase, $concepts);
1391         } else {
1392             $exists = in_array(textlib::strtolower($filterobject->phrase), $lconcepts);
1393         }
1394
1395         if (!$exists) {
1396             $cleanlinks[] = $filterobject;
1397             $concepts[] = $filterobject->phrase;
1398             $lconcepts[] = textlib::strtolower($filterobject->phrase);
1399         }
1400     }
1401
1402     return $cleanlinks;
1403 }
1404
1405 /**
1406  * Extract open/lose tags and their contents to avoid being processed by filters.
1407  * Useful to extract pieces of code like <a>...</a> tags. It returns the text
1408  * converted with some <#xTEXTFILTER_EXCL_SEPARATORx#> codes replacing the extracted text. Such extracted
1409  * texts are returned in the ignoretags array (as values), with codes as keys.
1410  *
1411  * @param string $text                  the text that we are filtering (in/out)
1412  * @param array $filterignoretagsopen  an array of open tags to start searching
1413  * @param array $filterignoretagsclose an array of close tags to end searching
1414  * @param array $ignoretags            an array of saved strings useful to rebuild the original text (in/out)
1415  **/
1416 function filter_save_ignore_tags(&$text, $filterignoretagsopen, $filterignoretagsclose, &$ignoretags) {
1417
1418 /// Remove everything enclosed by the ignore tags from $text
1419     foreach ($filterignoretagsopen as $ikey=>$opentag) {
1420         $closetag = $filterignoretagsclose[$ikey];
1421     /// form regular expression
1422         $opentag  = str_replace('/','\/',$opentag); // delimit forward slashes
1423         $closetag = str_replace('/','\/',$closetag); // delimit forward slashes
1424         $pregexp = '/'.$opentag.'(.*?)'.$closetag.'/is';
1425
1426         preg_match_all($pregexp, $text, $list_of_ignores);
1427         foreach (array_unique($list_of_ignores[0]) as $key=>$value) {
1428             $prefix = (string)(count($ignoretags) + 1);
1429             $ignoretags['<#'.$prefix.TEXTFILTER_EXCL_SEPARATOR.$key.'#>'] = $value;
1430         }
1431         if (!empty($ignoretags)) {
1432             $text = str_replace($ignoretags,array_keys($ignoretags),$text);
1433         }
1434     }
1435 }
1436
1437 /**
1438  * Extract tags (any text enclosed by < and > to avoid being processed by filters.
1439  * It returns the text converted with some <%xTEXTFILTER_EXCL_SEPARATORx%> codes replacing the extracted text. Such extracted
1440  * texts are returned in the tags array (as values), with codes as keys.
1441  *
1442  * @param string $text   the text that we are filtering (in/out)
1443  * @param array $tags   an array of saved strings useful to rebuild the original text (in/out)
1444  **/
1445 function filter_save_tags(&$text, &$tags) {
1446
1447     preg_match_all('/<([^#%*].*?)>/is',$text,$list_of_newtags);
1448     foreach (array_unique($list_of_newtags[0]) as $ntkey=>$value) {
1449         $prefix = (string)(count($tags) + 1);
1450         $tags['<%'.$prefix.TEXTFILTER_EXCL_SEPARATOR.$ntkey.'%>'] = $value;
1451     }
1452     if (!empty($tags)) {
1453         $text = str_replace($tags,array_keys($tags),$text);
1454     }
1455 }
1456
1457 /**
1458  * Add missing openpopup javascript to HTML files.
1459  *
1460  * @param string $text
1461  * @return string
1462  */
1463 function filter_add_javascript($text) {
1464     global $CFG;
1465
1466     if (stripos($text, '</html>') === FALSE) {
1467         return $text; // this is not a html file
1468     }
1469     if (strpos($text, 'onclick="return openpopup') === FALSE) {
1470         return $text; // no popup - no need to add javascript
1471     }
1472     $js ="
1473     <script type=\"text/javascript\">
1474     <!--
1475         function openpopup(url,name,options,fullscreen) {
1476           fullurl = \"".$CFG->httpswwwroot."\" + url;
1477           windowobj = window.open(fullurl,name,options);
1478           if (fullscreen) {
1479             windowobj.moveTo(0,0);
1480             windowobj.resizeTo(screen.availWidth,screen.availHeight);
1481           }
1482           windowobj.focus();
1483           return false;
1484         }
1485     // -->
1486     </script>";
1487     if (stripos($text, '</head>') !== FALSE) {
1488         //try to add it into the head element
1489         $text = str_ireplace('</head>', $js.'</head>', $text);
1490         return $text;
1491     }
1492
1493     //last chance - try adding head element
1494     return preg_replace("/<html.*?>/is", "\\0<head>".$js.'</head>', $text);
1495 }