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250 lines
10 KiB
250 lines
10 KiB
2 years ago
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<?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 if (preg_match('/\\\\[[(]/', $text) || preg_match('/\$\$/', $text)) {
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// Only parse the text if there are mathjax symbols in it. The recognized
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// math environments are \[ \] and $$ $$ for display mathematics and \( \)
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// for inline mathematics.
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// Note: 2 separate regexes seems to perform better here than using a single
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// regex with groupings.
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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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