MDL-45009 Tex filter: Add \( \) delimiters for 1:1 compatibility with…

… MathJax

filter/tex/filter.php

@@ -114,7 +114,11 @@ function filter($text, array $options = array()) {
         global $CFG, $DB;
 
         /// Do a quick check using stripos to avoid unnecessary work
-        if (!preg_match('/<tex/i',$text) and !strstr($text,'$$') and !strstr($text,'\\[') and !preg_match('/\[tex/i',$text)) { //added one more tag (dlnsk)
+        if ((!preg_match('/<tex/i', $text)) &&
+                (strpos($text,'$$') === false) &&
+                (strpos($text,'\\[') === false) &&
+                (strpos($text, '\\(') === false) &&
+                (!preg_match('/\[tex/i',$text))) {
             return $text;
         }
 
@@ -146,9 +150,20 @@ function filter($text, array $options = array()) {
         // or $$ TeX expression $$
         // or \[ TeX expression \]          // original tag of MathType and TeXaide (dlnsk)
         // or [tex] TeX expression [/tex]   // somtime it's more comfortable than <tex> (dlnsk)
-        preg_match_all('/<tex(?:\s+alt=["\'](.*?)["\'])?>(.+?)<\/tex>|\$\$(.+?)\$\$|\\\\\[(.+?)\\\\\]|\\[tex\\](.+?)\\[\/tex\\]/is', $text, $matches);
+        $rules = array(
+            '<tex(?:\s+alt=["\'](.*?)["\'])?>(.+?)<\/tex>',
+            '\$\$(.+?)\$\$',
+            '\\\\\[(.+?)\\\\\]',
+            '\\\\\((.+?)\\\\\)',
+            '\\[tex\\](.+?)\\[\/tex\\]'
+        );
+        $megarule = '/' . implode($rules, '|') . '/is';
+        preg_match_all($megarule, $text, $matches);
         for ($i=0; $i<count($matches[0]); $i++) {
-            $texexp = $matches[2][$i] . $matches[3][$i] . $matches[4][$i] . $matches[5][$i];
+            $texexp = '';
+            for ($j = 0; $j < count($rules); $j++) {
+                $texexp .= $matches[$j + 2][$i];
+            }
             $alt = $matches[1][$i];
             $texexp = str_replace('<nolink>','',$texexp);
             $texexp = str_replace('</nolink>','',$texexp);

filter/tex/tests/filter_test.php

@@ -0,0 +1,81 @@
+<?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/>.
+
+/**
+ * Unit test for the filter_tex
+ *
+ * @package    filter_tex
+ * @copyright  2014 Damyon Wiese
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+defined('MOODLE_INTERNAL') || die();
+
+global $CFG;
+require_once($CFG->dirroot . '/filter/tex/filter.php');
+
+
+/**
+ * Unit tests for filter_tex.
+ *
+ * Test the delimiter parsing used by the tex filter.
+ *
+ * @copyright  2014 Damyon Wiese
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class filter_tex_testcase extends advanced_testcase {
+
+    protected $filter;
+
+    protected function setUp() {
+        parent::setUp();
+        $this->resetAfterTest(true);
+        $this->filter = new filter_tex(context_system::instance(), array());
+    }
+
+    function run_with_delimiters($start, $end, $filtershouldrun) {
+        $pre = 'Some pre text';
+        $post = 'Some post text';
+        $equation = ' \sum{a^b} ';
+
+        $before = $pre . $start . $equation . $end . $post;
+
+        $after = trim($this->filter->filter($before));
+
+        if ($filtershouldrun) {
+            $this->assertNotEquals($after, $before);
+        } else {
+            $this->assertEquals($after, $before);
+        }
+    }
+
+    function test_delimiters() {
+        // First test the list of supported delimiters.
+        $this->run_with_delimiters('$$', '$$', true);
+        $this->run_with_delimiters('\\(', '\\)', true);
+        $this->run_with_delimiters('\\[', '\\]', true);
+        $this->run_with_delimiters('[tex]', '[/tex]', true);
+        $this->run_with_delimiters('<tex>', '</tex>', true);
+        $this->run_with_delimiters('<tex alt="nonsense">', '</tex>', true);
+        // Now test some cases that shouldn't be executed.
+        $this->run_with_delimiters('<textarea>', '</textarea>', false);
+        $this->run_with_delimiters('$', '$', false);
+        $this->run_with_delimiters('(', ')', false);
+        $this->run_with_delimiters('[', ']', false);
+        $this->run_with_delimiters('$$', '\\]', false);
+    }
+
+}