[Summary view]

Differences Between: [Versions 310 and 403]

   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  
  40          // List of language codes found in the MathJax/localization/ directory.
  41          $mathjaxlangcodes = [
  42              'ar', 'ast', 'bcc', 'bg', 'br', 'ca', 'cdo', 'ce', 'cs', 'cy', 'da', 'de', 'diq', 'en', 'eo', 'es', 'fa',
  43              'fi', 'fr', 'gl', 'he', 'ia', 'it', 'ja', 'kn', 'ko', 'lb', 'lki', 'lt', 'mk', 'nl', 'oc', 'pl', 'pt',
  44              'pt-br', 'qqq', 'ru', 'scn', 'sco', 'sk', 'sl', 'sv', 'th', 'tr', 'uk', 'vi', 'zh-hans', 'zh-hant'
  45          ];
  46  
  47          // List of explicit mappings and known exceptions (moodle => mathjax).
  48          $explicit = [
  49              'cz' => 'cs',
  50              'pt_br' => 'pt-br',
  51              'zh_tw' => 'zh-hant',
  52              'zh_cn' => 'zh-hans',
  53          ];
  54  
  55          // If defined, explicit mapping takes the highest precedence.
  56          if (isset($explicit[$moodlelangcode])) {
  57              return $explicit[$moodlelangcode];
  58          }
  59  
  60          // If there is exact match, it will be probably right.
  61          if (in_array($moodlelangcode, $mathjaxlangcodes)) {
  62              return $moodlelangcode;
  63          }
  64  
  65          // Finally try to find the best matching mathjax pack.
  66          $parts = explode('_', $moodlelangcode, 2);
  67          if (in_array($parts[0], $mathjaxlangcodes)) {
  68              return $parts[0];
  69          }
  70  
  71          // No more guessing, use English.
  72          return 'en';
  73      }
  74  
  75      /*
  76       * Add the javascript to enable mathjax processing on this page.
  77       *
  78       * @param moodle_page $page The current page.
  79       * @param context $context The current context.
  80       */
  81      public function setup($page, $context) {
  82  
  83          if ($page->requires->should_create_one_time_item_now('filter_mathjaxloader-scripts')) {
  84              $url = get_config('filter_mathjaxloader', 'httpsurl');
  85              $lang = $this->map_language_code(current_language());
  86              $url = new moodle_url($url, array('delayStartupUntil' => 'configured'));
  87  
  88              $moduleconfig = array(
  89                  'name' => 'mathjax',
  90                  'fullpath' => $url
  91              );
  92  
  93              $page->requires->js_module($moduleconfig);
  94  
  95              $config = get_config('filter_mathjaxloader', 'mathjaxconfig');
  96              $wwwroot = new moodle_url('/');
  97  
  98              $config = str_replace('{wwwroot}', $wwwroot->out(true), $config);
  99  
 100              $params = array('mathjaxconfig' => $config, 'lang' => $lang);
 101  
 102              $page->requires->yui_module('moodle-filter_mathjaxloader-loader', 'M.filter_mathjaxloader.configure', array($params));
 103          }
 104      }
 105  
 106      /*
 107       * This function wraps the filtered text in a span, that mathjaxloader is configured to process.
 108       *
 109       * @param string $text The text to filter.
 110       * @param array $options The filter options.
 111       */
 112      public function filter($text, array $options = array()) {
 113          global $PAGE;
 114  
 115          $legacy = get_config('filter_mathjaxloader', 'texfiltercompatibility');
 116          $extradelimiters = explode(',', get_config('filter_mathjaxloader', 'additionaldelimiters'));
 117          if ($legacy) {
 118              // This replaces any of the tex filter maths delimiters with the default for inline maths in MathJAX "\( blah \)".
 119              // E.g. "<tex.*> blah </tex>".
 120              $text = preg_replace('|<(/?) *tex( [^>]*)?>|u', '[\1tex]', $text);
 121              // E.g. "[tex.*] blah [/tex]".
 122              $text = str_replace('[tex]', '\\(', $text);
 123              $text = str_replace('[/tex]', '\\)', $text);
 124              // E.g. "$$ blah $$".
 125              $text = preg_replace('|\$\$([\S\s]*?)\$\$|u', '\\(\1\\)', $text);
 126              // E.g. "\[ blah \]".
 127              $text = str_replace('\\[', '\\(', $text);
 128              $text = str_replace('\\]', '\\)', $text);
 129          }
 130  
 131          $hasextra = false;
 132          foreach ($extradelimiters as $extra) {
 133              if ($extra && strpos($text, $extra) !== false) {
 134                  $hasextra = true;
 135                  break;
 136              }
 137          }
 138  
 139          $hasdisplayorinline = false;
 140          if ($hasextra) {
 141              // If custom dilimeters are used, wrap whole text to prevent autolinking.
 142              $text = '<span class="nolink">' . $text . '</span>';
 143          } else if (preg_match('/\\\\[[(]/', $text) || preg_match('/\$\$/', $text)) {
 144              // Only parse the text if there are mathjax symbols in it. The recognized
 145              // math environments are \[ \] and $$ $$ for display mathematics and \( \)
 146              // for inline mathematics.
 147              // Note: 2 separate regexes seems to perform better here than using a single
 148              // regex with groupings.
 149  
 150              // Wrap display and inline math environments in nolink spans.
 151              // Do not wrap nested environments, i.e., if inline math is nested
 152              // inside display math, only the outer display math is wrapped in
 153              // a span. The span HTML inside a LaTex math environment would break
 154              // MathJax. See MDL-61981.
 155              list($text, $hasdisplayorinline) = $this->wrap_math_in_nolink($text);
 156          }
 157  
 158          if ($hasdisplayorinline || $hasextra) {
 159              $PAGE->requires->yui_module('moodle-filter_mathjaxloader-loader', 'M.filter_mathjaxloader.typeset');
 160              return '<span class="filter_mathjaxloader_equation">' . $text . '</span>';
 161          }
 162          return $text;
 163      }
 164  
 165      /**
 166       * Find math environments in the $text and wrap them in no link spans
 167       * (<span class="nolink"></span>). If math environments are nested, only
 168       * the outer environment is wrapped in the span.
 169       *
 170       * The recognized math environments are \[ \] and $$ $$ for display
 171       * mathematics and \( \) for inline mathematics.
 172       *
 173       * @param string $text The text to filter.
 174       * @return array An array containing the potentially modified text and
 175       * a boolean that is true if any changes were made to the text.
 176       */
 177      protected function wrap_math_in_nolink($text) {
 178          $i = 1;
 179          $len = strlen($text);
 180          $displaystart = -1;
 181          $displaybracket = false;
 182          $displaydollar = false;
 183          $inlinestart = -1;
 184          $changesdone = false;
 185          // Loop over the $text once.
 186          while ($i < $len) {
 187              if ($displaystart === -1) {
 188                  // No display math has started yet.
 189                  if ($text[$i - 1] === '\\' && $text[$i] === '[') {
 190                      // Display mode \[ begins.
 191                      $displaystart = $i - 1;
 192                      $displaybracket = true;
 193                  } else if ($text[$i - 1] === '$' && $text[$i] === '$') {
 194                      // Display mode $$ begins.
 195                      $displaystart = $i - 1;
 196                      $displaydollar = true;
 197                  } else if ($text[$i - 1] === '\\' && $text[$i] === '(') {
 198                      // Inline math \( begins, not nested inside display math.
 199                      $inlinestart = $i - 1;
 200                  } else if ($text[$i - 1] === '\\' && $text[$i] === ')' && $inlinestart > -1) {
 201                      // Inline math ends, not nested inside display math.
 202                      // Wrap the span around it.
 203                      $text = $this->insert_span($text, $inlinestart, $i);
 204  
 205                      $inlinestart = -1; // Reset.
 206                      $i += 28; // The $text length changed due to the <span>.
 207                      $len += 28;
 208                      $changesdone = true;
 209                  }
 210              } else {
 211                  // Display math open.
 212                  if (($text[$i - 1] === '\\' && $text[$i] === ']' && $displaybracket) ||
 213                          ($text[$i - 1] === '$' && $text[$i] === '$' && $displaydollar)) {
 214                      // Display math ends, wrap the span around it.
 215                      $text = $this->insert_span($text, $displaystart, $i);
 216  
 217                      $displaystart = -1; // Reset.
 218                      $displaybracket = false;
 219                      $displaydollar = false;
 220                      $i += 28; // The $text length changed due to the <span>.
 221                      $len += 28;
 222                      $changesdone = true;
 223                  }
 224              }
 225  
 226              ++$i;
 227          }
 228          return array($text, $changesdone);
 229      }
 230  
 231      /**
 232       * Wrap a portion of the $text inside a no link span
 233       * (<span class="nolink"></span>). The whole text is then returned.
 234       *
 235       * @param string $text The text to modify.
 236       * @param int $start The start index of the substring in $text that should
 237       * be wrapped in the span.
 238       * @param int $end The end index of the substring in $text that should be
 239       * wrapped in the span.
 240       * @return string The whole $text with the span inserted around
 241       * the defined substring.
 242       */
 243      protected function insert_span($text, $start, $end) {
 244          return substr_replace($text,
 245                  '<span class="nolink">'. substr($text, $start, $end - $start + 1) .'</span>',
 246                  $start,
 247                  $end - $start + 1);
 248      }
 249  }