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   1  <?php
   2  // This file is part of Moodle - http://moodle.org/
   3  //
   4  // Moodle is free software: you can redistribute it and/or modify
   5  // it under the terms of the GNU General Public License as published by
   6  // the Free Software Foundation, either version 3 of the License, or
   7  // (at your option) any later version.
   8  //
   9  // Moodle is distributed in the hope that it will be useful,
  10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  // GNU General Public License for more details.
  13  //
  14  // You should have received a copy of the GNU General Public License
  15  // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16  
  17  /**
  18   * This filter provides automatic support for MathJax
  19   *
  20   * @package    filter_mathjaxloader
  21   * @copyright  2013 Damyon Wiese (damyon@moodle.com)
  22   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  23   */
  24  
  25  defined('MOODLE_INTERNAL') || die();
  26  
  27  /**
  28   * Mathjax filtering
  29   */
  30  class filter_mathjaxloader extends moodle_text_filter {
  31  
  32      /*
  33       * Perform a mapping of the moodle language code to the equivalent for MathJax.
  34       *
  35       * @param string $moodlelangcode - The moodle language code - e.g. en_pirate
  36       * @return string The MathJax language code.
  37       */
  38      public function map_language_code($moodlelangcode) {
  39          $mathjaxlangcodes = array('br',
  40                                    'cdo',
  41                                    'cs',
  42                                    'da',
  43                                    'de',
  44                                    'en',
  45                                    'eo',
  46                                    'es',
  47                                    'fa',
  48                                    'fi',
  49                                    'fr',
  50                                    'gl',
  51                                    'he',
  52                                    'ia',
  53                                    'it',
  54                                    'ja',
  55                                    'ko',
  56                                    'lb',
  57                                    'mk',
  58                                    'nl',
  59                                    'oc',
  60                                    'pl',
  61                                    'pt',
  62                                    'pt-br',
  63                                    'ru',
  64                                    'sl',
  65                                    'sv',
  66                                    'tr',
  67                                    'uk',
  68                                    'zh-hans');
  69          $exceptions = array('cz' => 'cs');
  70  
  71          // First see if this is an exception.
  72          if (isset($exceptions[$moodlelangcode])) {
  73              $moodlelangcode = $exceptions[$moodlelangcode];
  74          }
  75  
  76          // Now look for an exact lang string match.
  77          if (in_array($moodlelangcode, $mathjaxlangcodes)) {
  78              return $moodlelangcode;
  79          }
  80  
  81          // Now try shortening the moodle lang string.
  82          $moodlelangcode = preg_replace('/-.*/', '', $moodlelangcode);
  83          // Look for a match on the shortened string.
  84          if (in_array($moodlelangcode, $mathjaxlangcodes)) {
  85              return $moodlelangcode;
  86          }
  87          // All failed - use english.
  88          return 'en';
  89      }
  90  
  91      /*
  92       * Add the javascript to enable mathjax processing on this page.
  93       *
  94       * @param moodle_page $page The current page.
  95       * @param context $context The current context.
  96       */
  97      public function setup($page, $context) {
  98          // This only requires execution once per request.
  99          static $jsinitialised = false;
 100  
 101          if (empty($jsinitialised)) {
 102              if (is_https()) {
 103                  $url = get_config('filter_mathjaxloader', 'httpsurl');
 104              } else {
 105                  $url = get_config('filter_mathjaxloader', 'httpurl');
 106              }
 107              $lang = $this->map_language_code(current_language());
 108              $url = new moodle_url($url, array('delayStartupUntil' => 'configured'));
 109  
 110              $moduleconfig = array(
 111                  'name' => 'mathjax',
 112                  'fullpath' => $url
 113              );
 114  
 115              $page->requires->js_module($moduleconfig);
 116  
 117              $config = get_config('filter_mathjaxloader', 'mathjaxconfig');
 118  
 119              $params = array('mathjaxconfig' => $config, 'lang' => $lang);
 120  
 121              $page->requires->yui_module('moodle-filter_mathjaxloader-loader', 'M.filter_mathjaxloader.configure', array($params));
 122  
 123              $jsinitialised = true;
 124          }
 125      }
 126  
 127      /*
 128       * This function wraps the filtered text in a span, that mathjaxloader is configured to process.
 129       *
 130       * @param string $text The text to filter.
 131       * @param array $options The filter options.
 132       */
 133      public function filter($text, array $options = array()) {
 134          global $PAGE;
 135  
 136          $legacy = get_config('filter_mathjaxloader', 'texfiltercompatibility');
 137          $extradelimiters = explode(',', get_config('filter_mathjaxloader', 'additionaldelimiters'));
 138          if ($legacy) {
 139              // This replaces any of the tex filter maths delimiters with the default for inline maths in MathJAX "\( blah \)".
 140              // E.g. "<tex.*> blah </tex>".
 141              $text = preg_replace('|<(/?) *tex( [^>]*)?>|u', '[\1tex]', $text);
 142              // E.g. "[tex.*] blah [/tex]".
 143              $text = str_replace('[tex]', '\\(', $text);
 144              $text = str_replace('[/tex]', '\\)', $text);
 145              // E.g. "$$ blah $$".
 146              $text = preg_replace('|\$\$([\S\s]*?)\$\$|u', '\\(\1\\)', $text);
 147              // E.g. "\[ blah \]".
 148              $text = str_replace('\\[', '\\(', $text);
 149              $text = str_replace('\\]', '\\)', $text);
 150          }
 151  
 152          $hasinline = strpos($text, '\\(') !== false && strpos($text, '\\)') !== false;
 153          $hasdisplay = (strpos($text, '$$') !== false) ||
 154                        (strpos($text, '\\[') !== false && strpos($text, '\\]') !== false);
 155  
 156          $hasextra = false;
 157  
 158          foreach ($extradelimiters as $extra) {
 159              if ($extra && strpos($text, $extra) !== false) {
 160                  $hasextra = true;
 161                  break;
 162              }
 163          }
 164          if ($hasinline || $hasdisplay || $hasextra) {
 165              $PAGE->requires->yui_module('moodle-filter_mathjaxloader-loader', 'M.filter_mathjaxloader.typeset');
 166              if ($hasextra) {
 167                  // If custom dilimeters are used, wrap whole text to prevent autolinking.
 168                  $text = '<span class="nolink">' + $text + '</span>';
 169              } else {
 170                  if ($hasinline) {
 171                      // If the default inline TeX delimiters \( \) are present, wrap each pair in nolink.
 172                      $text = preg_replace('/\\\\\\([\S\s]*?\\\\\\)/u',
 173                          '<span class="nolink">\0</span>', $text);
 174                  }
 175                  if ($hasdisplay) {
 176                      // If default display TeX is used, wrap $$ $$ or \[ \] individually.
 177                      $text = preg_replace('/\$\$[\S\s]*?\$\$|\\\\\\[[\S\s]*?\\\\\\]/u',
 178                          '<span class="nolink">\0</span>', $text);
 179                  }
 180              }
 181              return '<span class="filter_mathjaxloader_equation">' . $text . '</span>';
 182          }
 183          return $text;
 184      }
 185  }