Index: modules/taxonomy/taxonomy.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/taxonomy/taxonomy.module,v
retrieving revision 1.603
diff -u -p -r1.603 taxonomy.module
--- modules/taxonomy/taxonomy.module	22 Aug 2010 15:45:03 -0000	1.603
+++ modules/taxonomy/taxonomy.module	30 Aug 2010 11:22:43 -0000
@@ -801,21 +801,17 @@ function taxonomy_get_children($tid, $vi
  *   for the entire vocabulary.
  * @param $max_depth
  *   The number of levels of the tree to return. Leave NULL to return all levels.
- * @param $depth
- *   Internal use only.
  *
  * @return
  *   An array of all term objects in the tree. Each term object is extended
  *   to have "depth" and "parents" attributes in addition to its normal ones.
  *   Results are statically cached.
  */
-function taxonomy_get_tree($vid, $parent = 0, $max_depth = NULL, $depth = -1) {
+function taxonomy_get_tree($vid, $parent = 0, $max_depth = NULL) {
   $children = &drupal_static(__FUNCTION__, array());
   $parents = &drupal_static(__FUNCTION__ . ':parents', array());
   $terms = &drupal_static(__FUNCTION__ . ':terms', array());
 
-  $depth++;
-
   // We cache trees, so it's not CPU-intensive to call get_tree() on a term
   // and its children, too.
   if (!isset($children[$vid])) {
@@ -839,19 +835,46 @@ function taxonomy_get_tree($vid, $parent
       $parents[$vid][$tid][] = $parent_tid;
     }
   }
-
-  $max_depth = (is_null($max_depth)) ? count($children[$vid]) : $max_depth;
+  
   $tree = array();
-  if ($max_depth > $depth && !empty($children[$vid][$parent])) {
-    foreach ($children[$vid][$parent] as $child) {
-      $term = clone $terms[$vid][$child];
-      $term->depth = $depth;
-      $term->parents = $parents[$vid][$child];
-      $tree[] = $term;
-      if (!empty($children[$vid][$child])) {
-        $tree = array_merge($tree, taxonomy_get_tree($vid, $child, $max_depth, $depth));
+  $max_depth = (is_null($max_depth)) ? count($children[$vid]) : $max_depth;
+  $prev_parents = array(); //stores the parents we have to process
+  while (true) {
+    $depth = count($prev_parents);
+    if ($max_depth > $depth && !empty($children[$vid][$parent])) {
+      $has_children = FALSE;
+      $child = current($children[$vid][$parent]);
+      do {
+        if (empty($child)) {
+          break;
+        }
+        $term = clone $terms[$vid][$child];
+        $term->depth = $depth;
+        $term->parents = $parents[$vid][$child];
+        $tree[] = $term;
+        if (!empty($children[$vid][$child])) {
+          $prev_parents[] = $parent; //we have to continue with the current parent later
+          $prev_parents[] = $child;  //use $child for the next iteration
+          reset($children[$vid][$child]); // reset pointers for child lists as we step in there more often with multi parents
+          next($children[$vid][$parent]); //move pointer so that we get the correct term the next time
+          $has_children = TRUE;
+          break;
+        }
+      } while ($child = next($children[$vid][$parent]));
+     
+      if (!$has_children) {
+        //we processed all terms in this hierarchy-level
+        //reset pointer so that this function works the next time it gets called
+        reset($children[$vid][$parent]);
       }
     }
+
+    if (count($prev_parents)) {
+      $parent = array_pop($prev_parents);
+    }
+    else {
+      break;
+    }
   }
 
   return $tree;