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/
filter.php
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/
filter.php
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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/>.
/**
* Moodle - Filter for converting simple calculator-type algebraic
* expressions to cached gif images
*
* @package filter
* @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
*/
defined('MOODLE_INTERNAL') || die();
//-------------------------------------------------------------------------
// 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
//-------------------------------------------------------------------------
function filter_algebra_image($imagefile, $tex= "", $height="", $width="", $align="middle") {
// 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 .= "\" $style />";
if (!file_exists("$CFG->dataroot/filter/algebra/$imagefile") && has_capability('moodle/site:config', get_context_instance(CONTEXT_SYSTEM))) {
$link = '/filter/algebra/algebradebug.php';
$action = null;
} else {
$link = new moodle_url('/filter/tex/displaytex.php', array('texexp'=>$tex));
$action = new popup_action('click', $link, 'popup', array('width'=>320,'height'=>240)); //TODO: the popups do not work when text caching is enabled!!
}
$output .= $OUTPUT->action_link($link, $anchorcontents, $action, array('title'=>'TeX'));
} else {
$output .= "Error: must pass URL or course";
}
return $output;
}
class filter_algebra extends moodle_text_filter {
public function filter($text, array $options = array()){
global $CFG, $DB;
/// Do a quick check using stripos to avoid unnecessary wor
if (!preg_match('/<algebra/i',$text) && !strstr($text,'@@')) {
return $text;
}
//restrict filtering to forum 130 (Maths Tools on moodle.org)
# $scriptname = $_SERVER['SCRIPT_NAME'];
# if (!strstr($scriptname,'/forum/')) {
# return $text;
# }
# if (strstr($scriptname,'post.php')) {
# $parent = forum_get_post_full($_GET['reply']);
# $discussion = $DB->get_record("forum_discussions",array("id"=>$parent->discussion));
# } else if (strstr($scriptname,'discuss.php')) {
# $discussion = $DB->get_record("forum_discussions",array("id"=>$_GET['d']));
# } else {
# return $text;
# }
# if ($discussion->forum != 130) {
# 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);
}
// <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 = $DB->get_record("cache_filters",array("filter"=>"algebra", "md5key"=>$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('/\\\frac{(.+?)}{\\\left\((.+?)\\\right\)}/s','\frac{'."\$1}{\$2}",$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);
$texexp = str_replace('\mbox', '', $texexp); // now blacklisted in tex, sorry
$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], filter_algebra_image($filename, $texexp, '', '', $align), $text);
} else {
$text = str_replace( $matches[0][$i],"<b>Undetermined error:</b> ",$text);
}
} else {
$text = str_replace( $matches[0][$i], filter_algebra_image($filename, $texcache->rawtext), $text);
}
}
return $text;
}
}