? format_old.php
Index: format.php
===================================================================
RCS file: /cvsroot/moodle/moodle/question/format/gift/format.php,v
retrieving revision 1.41
diff -u -r1.41 format.php
--- format.php	23 Jun 2011 09:40:08 -0000	1.41
+++ format.php	24 Aug 2011 20:15:20 -0000
@@ -56,7 +56,12 @@
  * members of the Moodle community. It was originally based on
  * the missingword format, which included code from Thomas Robb
  * and others. Paul Tsuchido Shew wrote this filter in December 2003.
- *
+ * 
+ * Modified by Gian Paolo Leonardi in July 2011 to avoid escaping of
+ * control characters in TeX/LaTeX regions delimited by pairs of double dollars:
+ * with this new gift format, the insertion of TeX/LaTeX commands in the 
+ * question text is done without escaping of control characters.
+ *  
  * @copyright  2003 Paul Tsuchido Shew
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
@@ -112,19 +117,42 @@
 
     protected function escapedchar_pre($string) {
         //Replaces escaped control characters with a placeholder BEFORE processing
+        //Modified (July 2011) by Gian Paolo Leonardi to avoid escaping within TeX/LaTeX regions
 
-        $escapedcharacters = array("\\:",    "\\#",    "\\=",    "\\{",    "\\}",    "\\~",    "\\n"  );  //dlnsk
-        $placeholders      = array("&&058;", "&&035;", "&&061;", "&&123;", "&&125;", "&&126;", "&&010");  //dlnsk
+      $escapedcharacters = array("\\:",    "\\#",    "\\=",    "\\{",    "\\}",    "\\~",    "\\n"  );  //dlnsk
 
-        $string = str_replace("\\\\", "&&092;", $string);
-        $string = str_replace($escapedcharacters, $placeholders, $string);
-        $string = str_replace("&&092;", "\\", $string);
-        return $string;
+      $placeholders      = array("&&058;", "&&035;", "&&061;", "&&123;", "&&125;", "&&126;", "&&010");  //dlnsk
+
+      $texescapedcharacters = array(":",      "#",      "=",      "{",      "}",      "~");  //dlnsk
+
+      $texplaceholders      = array("&&058;", "&&035;", "&&061;", "&&123;", "&&125;", "&&126;");  //dlnsk
+
+      $chunks = explode("$$", $string);
+      reset($chunks);
+      $counter = 1;
+      $stringa = "";
+      while ($achunk = each($chunks)) {
+	$chunk = $achunk[1];
+	if ($counter % 2) {
+	  $chunk = str_replace("\\\\", "&&092;", $chunk);
+	  $chunk = str_replace($escapedcharacters, $placeholders, $chunk);
+	  $chunk = str_replace("&&092;", "\\", $chunk);
+	}
+	else {
+	  $chunk = str_replace($texescapedcharacters, $texplaceholders, $chunk);
+	}
+	$stringa .= $chunk;
+	$stringa .= "$$";
+	$counter += 1;
+      }
+      $stringa = rtrim($stringa, "$");
+      return $stringa;
     }
 
     protected function escapedchar_post($string) {
         //Replaces placeholders with corresponding character AFTER processing is done
-        $placeholders = array("&&058;", "&&035;", "&&061;", "&&123;", "&&125;", "&&126;", "&&010"); //dlnsk
+        //Modified (July 2011) by Gian Paolo Leonardi to avoid escaping within TeX/LaTeX regions
+       $placeholders = array("&&058;", "&&035;", "&&061;", "&&123;", "&&125;", "&&126;", "&&010"); //dlnsk
         $characters   = array(":",     "#",      "=",      "{",      "}",      "~",      "\n"  ); //dlnsk
         $string = str_replace($placeholders, $characters, $string);
         return $string;
@@ -552,11 +580,28 @@
     protected function repchar($text, $notused = 0) {
         // Escapes 'reserved' characters # = ~ {) :
         // Removes new lines
+        // Modified (July 2011) by Gian Paolo Leonardi to avoid escaping within TeX/LaTeX regions
+
         $reserved = array( '#', '=', '~', '{', '}', ':', "\n", "\r");
         $escaped =  array('\#','\=','\~','\{','\}','\:', '\n', '' );
 
-        $newtext = str_replace($reserved, $escaped, $text);
-        return $newtext;
+      $chunks = explode("$$", $text);
+      reset($chunks);
+      $counter = 1;
+      $newtext = "";
+
+      while ($achunk = each($chunks)) {
+	$chunk = $achunk[1];
+	if ($counter % 2) {
+	  $chunk = str_replace($reserved, $escaped, $chunk);
+	}
+	$newtext .= $chunk;
+	$newtext .= "$$";
+	$counter += 1;
+      }
+      $newtext = rtrim($newtext, "$");
+
+      return $newtext;
     }
 
     /**