Markku Riekkinen
194ffa2344
The MathJax filter used to break mathematics if inline math was used inside display math. Nolink spans were added around the inline math even though it was nested inside another math environment. This fix is aware of the nesting so that the spans may be inserted only at the outer math environment. No regular expressions are used because they do not support detecting arbitrary, unlimited nesting of parentheses in the text, which is now needed.
244 lines
9.6 KiB
PHP
244 lines
9.6 KiB
PHP
<?php
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// This file is part of Moodle - http://moodle.org/
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//
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// Moodle is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// Moodle is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
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/**
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* This filter provides automatic support for MathJax
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*
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* @package filter_mathjaxloader
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* @copyright 2013 Damyon Wiese (damyon@moodle.com)
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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defined('MOODLE_INTERNAL') || die();
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/**
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* Mathjax filtering
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*/
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class filter_mathjaxloader extends moodle_text_filter {
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/*
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* Perform a mapping of the moodle language code to the equivalent for MathJax.
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*
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* @param string $moodlelangcode - The moodle language code - e.g. en_pirate
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* @return string The MathJax language code.
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*/
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public function map_language_code($moodlelangcode) {
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// List of language codes found in the MathJax/localization/ directory.
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$mathjaxlangcodes = [
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'ar', 'ast', 'bcc', 'bg', 'br', 'ca', 'cdo', 'ce', 'cs', 'cy', 'da', 'de', 'diq', 'en', 'eo', 'es', 'fa',
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'fi', 'fr', 'gl', 'he', 'ia', 'it', 'ja', 'kn', 'ko', 'lb', 'lki', 'lt', 'mk', 'nl', 'oc', 'pl', 'pt',
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'pt-br', 'qqq', 'ru', 'scn', 'sco', 'sk', 'sl', 'sv', 'th', 'tr', 'uk', 'vi', 'zh-hans', 'zh-hant'
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];
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// List of explicit mappings and known exceptions (moodle => mathjax).
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$explicit = [
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'cz' => 'cs',
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'pt_br' => 'pt-br',
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'zh_tw' => 'zh-hant',
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'zh_cn' => 'zh-hans',
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];
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// If defined, explicit mapping takes the highest precedence.
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if (isset($explicit[$moodlelangcode])) {
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return $explicit[$moodlelangcode];
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}
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// If there is exact match, it will be probably right.
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if (in_array($moodlelangcode, $mathjaxlangcodes)) {
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return $moodlelangcode;
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}
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// Finally try to find the best matching mathjax pack.
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$parts = explode('_', $moodlelangcode, 2);
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if (in_array($parts[0], $mathjaxlangcodes)) {
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return $parts[0];
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}
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// No more guessing, use English.
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return 'en';
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}
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/*
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* Add the javascript to enable mathjax processing on this page.
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*
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* @param moodle_page $page The current page.
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* @param context $context The current context.
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*/
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public function setup($page, $context) {
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if ($page->requires->should_create_one_time_item_now('filter_mathjaxloader-scripts')) {
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$url = get_config('filter_mathjaxloader', 'httpsurl');
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$lang = $this->map_language_code(current_language());
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$url = new moodle_url($url, array('delayStartupUntil' => 'configured'));
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$moduleconfig = array(
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'name' => 'mathjax',
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'fullpath' => $url
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);
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$page->requires->js_module($moduleconfig);
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$config = get_config('filter_mathjaxloader', 'mathjaxconfig');
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$wwwroot = new moodle_url('/');
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$config = str_replace('{wwwroot}', $wwwroot->out(true), $config);
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$params = array('mathjaxconfig' => $config, 'lang' => $lang);
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$page->requires->yui_module('moodle-filter_mathjaxloader-loader', 'M.filter_mathjaxloader.configure', array($params));
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}
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}
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/*
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* This function wraps the filtered text in a span, that mathjaxloader is configured to process.
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*
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* @param string $text The text to filter.
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* @param array $options The filter options.
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*/
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public function filter($text, array $options = array()) {
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global $PAGE;
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$legacy = get_config('filter_mathjaxloader', 'texfiltercompatibility');
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$extradelimiters = explode(',', get_config('filter_mathjaxloader', 'additionaldelimiters'));
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if ($legacy) {
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// This replaces any of the tex filter maths delimiters with the default for inline maths in MathJAX "\( blah \)".
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// E.g. "<tex.*> blah </tex>".
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$text = preg_replace('|<(/?) *tex( [^>]*)?>|u', '[\1tex]', $text);
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// E.g. "[tex.*] blah [/tex]".
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$text = str_replace('[tex]', '\\(', $text);
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$text = str_replace('[/tex]', '\\)', $text);
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// E.g. "$$ blah $$".
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$text = preg_replace('|\$\$([\S\s]*?)\$\$|u', '\\(\1\\)', $text);
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// E.g. "\[ blah \]".
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$text = str_replace('\\[', '\\(', $text);
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$text = str_replace('\\]', '\\)', $text);
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}
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$hasextra = false;
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foreach ($extradelimiters as $extra) {
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if ($extra && strpos($text, $extra) !== false) {
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$hasextra = true;
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break;
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}
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}
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$hasdisplayorinline = false;
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if ($hasextra) {
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// If custom dilimeters are used, wrap whole text to prevent autolinking.
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$text = '<span class="nolink">' . $text . '</span>';
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} else {
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// Wrap display and inline math environments in nolink spans.
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// Do not wrap nested environments, i.e., if inline math is nested
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// inside display math, only the outer display math is wrapped in
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// a span. The span HTML inside a LaTex math environment would break
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// MathJax. See MDL-61981.
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list($text, $hasdisplayorinline) = $this->wrap_math_in_nolink($text);
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}
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if ($hasdisplayorinline || $hasextra) {
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$PAGE->requires->yui_module('moodle-filter_mathjaxloader-loader', 'M.filter_mathjaxloader.typeset');
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return '<span class="filter_mathjaxloader_equation">' . $text . '</span>';
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}
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return $text;
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}
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/**
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* Find math environments in the $text and wrap them in no link spans
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* (<span class="nolink"></span>). If math environments are nested, only
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* the outer environment is wrapped in the span.
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*
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* The recognized math environments are \[ \] and $$ $$ for display
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* mathematics and \( \) for inline mathematics.
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*
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* @param string $text The text to filter.
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* @return array An array containing the potentially modified text and
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* a boolean that is true if any changes were made to the text.
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*/
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protected function wrap_math_in_nolink($text) {
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$i = 1;
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$len = strlen($text);
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$displaystart = -1;
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$displaybracket = false;
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$displaydollar = false;
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$inlinestart = -1;
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$changesdone = false;
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// Loop over the $text once.
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while ($i < $len) {
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if ($displaystart === -1) {
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// No display math has started yet.
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if ($text[$i - 1] === '\\' && $text[$i] === '[') {
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// Display mode \[ begins.
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$displaystart = $i - 1;
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$displaybracket = true;
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} else if ($text[$i - 1] === '$' && $text[$i] === '$') {
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// Display mode $$ begins.
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$displaystart = $i - 1;
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$displaydollar = true;
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} else if ($text[$i - 1] === '\\' && $text[$i] === '(') {
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// Inline math \( begins, not nested inside display math.
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$inlinestart = $i - 1;
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} else if ($text[$i - 1] === '\\' && $text[$i] === ')' && $inlinestart > -1) {
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// Inline math ends, not nested inside display math.
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// Wrap the span around it.
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$text = $this->insert_span($text, $inlinestart, $i);
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$inlinestart = -1; // Reset.
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$i += 28; // The $text length changed due to the <span>.
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$len += 28;
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$changesdone = true;
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}
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} else {
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// Display math open.
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if (($text[$i - 1] === '\\' && $text[$i] === ']' && $displaybracket) ||
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($text[$i - 1] === '$' && $text[$i] === '$' && $displaydollar)) {
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// Display math ends, wrap the span around it.
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$text = $this->insert_span($text, $displaystart, $i);
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$displaystart = -1; // Reset.
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$displaybracket = false;
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$displaydollar = false;
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$i += 28; // The $text length changed due to the <span>.
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$len += 28;
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$changesdone = true;
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}
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}
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++$i;
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}
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return array($text, $changesdone);
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}
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/**
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* Wrap a portion of the $text inside a no link span
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* (<span class="nolink"></span>). The whole text is then returned.
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*
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* @param string $text The text to modify.
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* @param int $start The start index of the substring in $text that should
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* be wrapped in the span.
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* @param int $end The end index of the substring in $text that should be
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* wrapped in the span.
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* @return string The whole $text with the span inserted around
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* the defined substring.
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*/
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protected function insert_span($text, $start, $end) {
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return substr_replace($text,
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'<span class="nolink">'. substr($text, $start, $end - $start + 1) .'</span>',
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$start,
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$end - $start + 1);
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}
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}
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