File: /home/enamadmin/public_html/aaelearningb/filter/algebra/classes/text_filter.php
<?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/>.
namespace filter_algebra;
use core\context\system as context_system;
use core\output\actions\popup_action;
use core\url;
use stdClass;
/**
* Moodle - Filter for converting simple calculator-type algebraic expressions to cached gif images
*
* NOTE: This Moodle text filter converts algebraic expressions delimited
* by either @@...@@ or by <algebra...>...</algebra> tags
* first converts it to TeX using WeBWorK algebra parser Perl library
* AlgParser.pm, part of the WeBWorK distribution obtained from
* http://webhost.math.rochester.edu/downloadwebwork/
* then converts the TeX to gif images using
* mimetex.cgi obtained from http://www.forkosh.com/mimetex.html authored by
* John Forkosh john@forkosh.com. The mimetex.cgi ELF binary compiled for Linux i386
* as well as AlgParser.pm are included with this distribution.
* Note that there may be patent restrictions on the production of gif images
* in Canada and some parts of Western Europe and Japan until July 2004.
* -------------------------------------------------------------------------
* You will then need to edit your moodle/config.php to invoke mathml_filter.php
* -------------------------------------------------------------------------
*
* @package filter_algebra
* @subpackage algebra
* @copyright 2004 Zbigniew Fiedorowicz fiedorow@math.ohio-state.edu
* Originally based on code provided by Bruno Vernier bruno@vsbeducation.ca
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class text_filter extends \core_filters\text_filter {
#[\Override]
public function filter($text, array $options = []) {
global $CFG, $DB;
// Do a quick check using stripos to avoid unnecessary work.
if (!preg_match('/<algebra/i', $text) && !strstr($text, '@@')) {
return $text;
}
preg_match_all('/@(@@+)([^@])/', $text, $matches);
for ($i = 0; $i < count($matches[0]); $i++) {
$replacement = str_replace('@', '@', $matches[1][$i]) . $matches[2][$i];
$text = str_replace($matches[0][$i], $replacement, $text);
}
// The following regular expression matches TeX expressions delimited by:
// <algebra> some algebraic input expression </algebra>
// or @@ some algebraic input expression @@.
preg_match_all('/<algebra>(.+?)<\/algebra>|@@(.+?)@@/is', $text, $matches);
for ($i = 0; $i < count($matches[0]); $i++) {
$algebra = $matches[1][$i] . $matches[2][$i];
// Look for some common false positives, and skip processing them.
if ($algebra == 'PLUGINFILE' || $algebra == 'DRAFTFILE') {
// Raw pluginfile URL.
continue;
}
if (preg_match('/^ -\d+(,\d+)? \+\d+(,\d+)? $/', $algebra)) {
// Part of a unified diff.
continue;
}
$algebra = str_replace('<nolink>', '', $algebra);
$algebra = str_replace('</nolink>', '', $algebra);
$algebra = str_replace('<span class="nolink">', '', $algebra);
$algebra = str_replace('</span>', '', $algebra);
$align = "middle";
if (preg_match('/^align=bottom /', $algebra)) {
$align = "text-bottom";
$algebra = preg_replace('/^align=bottom /', '', $algebra);
} else if (preg_match('/^align=top /', $algebra)) {
$align = "text-top";
$algebra = preg_replace('/^align=top /', '', $algebra);
}
$md5 = md5($algebra);
$filename = $md5 . ".gif";
if (! $texcache = $DB->get_record("cache_filters", ["filter" => "algebra", "md5key" => $md5])) {
$algebra = str_replace('<', '<', $algebra);
$algebra = str_replace('>', '>', $algebra);
$algebra = str_replace('<>', '#', $algebra);
$algebra = str_replace('<=', '%', $algebra);
$algebra = str_replace('>=', '!', $algebra);
$algebra = preg_replace('/([=><%!#] *)-/', "\$1 zeroplace -", $algebra);
$algebra = str_replace('delta', 'zdelta', $algebra);
$algebra = str_replace('beta', 'bita', $algebra);
$algebra = str_replace('theta', 'thita', $algebra);
$algebra = str_replace('zeta', 'zita', $algebra);
$algebra = str_replace('eta', 'xeta', $algebra);
$algebra = str_replace('epsilon', 'zepslon', $algebra);
$algebra = str_replace('upsilon', 'zupslon', $algebra);
$algebra = preg_replace('!\r\n?!', ' ', $algebra);
$algebra = escapeshellarg($algebra);
if ((PHP_OS == "WINNT") || (PHP_OS == "WIN32") || (PHP_OS == "Windows")) {
$cmd = "cd $CFG->dirroot\\filter\\algebra & algebra2tex.pl $algebra";
} else {
$cmd = "cd $CFG->dirroot/filter/algebra; ./algebra2tex.pl $algebra";
}
$texexp = `$cmd`;
if (preg_match('/parsehilight/', $texexp)) {
$text = str_replace($matches[0][$i], "<b>Syntax error:</b> " . $texexp, $text);
} else if ($texexp) {
$texexp = str_replace('zeroplace', '', $texexp);
$texexp = str_replace('#', '\not= ', $texexp);
$texexp = str_replace('%', '\leq ', $texexp);
$texexp = str_replace('!', '\geq ', $texexp);
$texexp = str_replace('\left{', '{', $texexp);
$texexp = str_replace('\right}', '}', $texexp);
$texexp = str_replace('\fun', ' ', $texexp);
$texexp = str_replace('infty', '\infty', $texexp);
$texexp = str_replace('alpha', '\alpha', $texexp);
$texexp = str_replace('gamma', '\gamma', $texexp);
$texexp = str_replace('iota', '\iota', $texexp);
$texexp = str_replace('kappa', '\kappa', $texexp);
$texexp = str_replace('lambda', '\lambda', $texexp);
$texexp = str_replace('mu', '\mu', $texexp);
$texexp = str_replace('nu', '\nu', $texexp);
$texexp = str_replace('xi', '\xi', $texexp);
$texexp = str_replace('rho', '\rho', $texexp);
$texexp = str_replace('sigma', '\sigma', $texexp);
$texexp = str_replace('tau', '\tau', $texexp);
$texexp = str_replace('phi', '\phi', $texexp);
$texexp = str_replace('chi', '\chi', $texexp);
$texexp = str_replace('psi', '\psi', $texexp);
$texexp = str_replace('omega', '\omega', $texexp);
$texexp = str_replace('zdelta', '\delta', $texexp);
$texexp = str_replace('bita', '\beta', $texexp);
$texexp = str_replace('thita', '\theta', $texexp);
$texexp = str_replace('zita', '\zeta', $texexp);
$texexp = str_replace('xeta', '\eta', $texexp);
$texexp = str_replace('zepslon', '\epsilon', $texexp);
$texexp = str_replace('zupslon', '\upsilon', $texexp);
$texexp = str_replace('\mbox{logten}', '\mbox{log}_{10}', $texexp);
$texexp = str_replace('\mbox{acos}', '\mbox{cos}^{-1}', $texexp);
$texexp = str_replace('\mbox{asin}', '\mbox{sin}^{-1}', $texexp);
$texexp = str_replace('\mbox{atan}', '\mbox{tan}^{-1}', $texexp);
$texexp = str_replace('\mbox{asec}', '\mbox{sec}^{-1}', $texexp);
$texexp = str_replace('\mbox{acsc}', '\mbox{csc}^{-1}', $texexp);
$texexp = str_replace('\mbox{acot}', '\mbox{cot}^{-1}', $texexp);
$texexp = str_replace('\mbox{acosh}', '\mbox{cosh}^{-1}', $texexp);
$texexp = str_replace('\mbox{asinh}', '\mbox{sinh}^{-1}', $texexp);
$texexp = str_replace('\mbox{atanh}', '\mbox{tanh}^{-1}', $texexp);
$texexp = str_replace('\mbox{asech}', '\mbox{sech}^{-1}', $texexp);
$texexp = str_replace('\mbox{acsch}', '\mbox{csch}^{-1}', $texexp);
$texexp = str_replace('\mbox{acoth}', '\mbox{coth}^{-1}', $texexp);
$texexp = preg_replace('/\\\sqrt{(.+?),(.+?)}/s', '\sqrt[' . "\$2]{\$1}", $texexp);
$texexp = preg_replace('/\\\mbox{abs}\\\left\((.+?)\\\right\)/s', "|\$1|", $texexp);
$texexp = preg_replace('/\\\log\\\left\((.+?),(.+?)\\\right\)/s', '\log_{' . "\$2}\\left(\$1\\right)", $texexp);
$texexp = preg_replace(
'/(\\\cos|\\\sin|\\\tan|\\\sec|\\\csc|\\\cot)([h]*)\\\left\((.+?),(.+?)\\\right\)/s',
"\$1\$2^{" . "\$4}\\left(\$3\\right)",
$texexp,
);
$texexp = preg_replace('/\\\int\\\left\((.+?),(.+?),(.+?)\\\right\)/s', '\int_' . "{\$2}^{\$3}\$1 ", $texexp);
$texexp = preg_replace('/\\\int\\\left\((.+?d[a-z])\\\right\)/s', '\int ' . "\$1 ", $texexp);
$texexp = preg_replace('/\\\lim\\\left\((.+?),(.+?),(.+?)\\\right\)/s', '\lim_' . "{\$2\\to \$3}\$1 ", $texexp);
// Remove a forbidden keyword.
$texexp = str_replace('\mbox', '', $texexp);
$texcache = new stdClass();
$texcache->filter = 'algebra';
$texcache->version = 1;
$texcache->md5key = $md5;
$texcache->rawtext = $texexp;
$texcache->timemodified = time();
$DB->insert_record("cache_filters", $texcache, false);
$text = str_replace($matches[0][$i], self::get_image_markup($filename, $texexp, 0, 0, $align), $text);
} else {
$text = str_replace($matches[0][$i], "<b>Undetermined error:</b> " . $matches[0][$i], $text);
}
} else {
$text = str_replace($matches[0][$i], self::get_image_markup($filename, $texcache->rawtext), $text);
}
}
return $text;
}
/**
* Create image link.
*
* @param string $imagefile name of file
* @param string $tex TeX notation (html entities already decoded)
* @param int $height O means automatic
* @param int $width O means automatic
* @param string $align
* @return string HTML markup
*/
protected function get_image_markup(
string $imagefile,
string $tex = "",
int $height = 0,
int $width = 0,
string $align = 'middle',
): string {
// Given the path to a picture file in a course, or a URL,
// this function includes the picture in the page.
global $CFG, $OUTPUT;
$output = "";
$style = 'style="border:0px; vertical-align:' . $align . ';';
$title = '';
if ($tex) {
$tex = html_entity_decode($tex, ENT_QUOTES, 'UTF-8');
$title = 'title="' . s($tex) . '"';
}
if ($height) {
$style .= " height:{$height}px;";
}
if ($width) {
$style .= " width:{$width}px;";
}
$style .= '"';
$anchorcontents = '';
if ($imagefile) {
$anchorcontents .= "<img $title alt=\"" . s($tex) . "\" src=\"";
if ($CFG->slasharguments) {
// Use this method if possible for better caching.
$anchorcontents .= "$CFG->wwwroot/filter/algebra/pix.php/$imagefile";
} else {
$anchorcontents .= "$CFG->wwwroot/filter/algebra/pix.php?file=$imagefile";
}
$anchorcontents .= "\" $style />";
$imagefound = file_exists("$CFG->dataroot/filter/algebra/$imagefile");
if (!$imagefound && has_capability('moodle/site:config', context_system::instance())) {
$link = '/filter/algebra/algebradebug.php';
$action = null;
} else {
$link = new url('/filter/tex/displaytex.php', ['texexp' => $tex]);
// TODO: the popups do not work when text caching is enabled.
$action = new popup_action('click', $link, 'popup', ['width' => 320, 'height' => 240]);
}
$output .= $OUTPUT->action_link($link, $anchorcontents, $action, ['title' => 'TeX']);
} else {
$output .= "Error: must pass URL or course";
}
return $output;
}
}