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