diff -r 7c15fea5cbea -r 1ce90ab4fab9 src/tree.c
--- a/src/tree.c	Mon Feb 19 22:12:13 2024 +0100
+++ b/src/tree.c	Wed Feb 21 18:32:38 2024 +0100
@@ -182,40 +182,58 @@
     off_t const loc_children = iter->loc_children;
 
     // TODO: support mutating iterator
-    // TODO: support visit_on_exit
 
-    void *children = tree_children(iter->node);
+    void *children;
+
+    // check if we are currently exiting or entering nodes
+    if (iter->exiting) {
+        children = NULL;
+    } else {
+        children = tree_children(iter->node);
+    }
+
     if (children == NULL) {
         // search for the next node
-        void *current = iter->node;
-        do {
-            // check if there is a sibling
-            void *next = tree_next(current);
-            if (next == NULL) {
-                // no sibling, check again for parent node
-                --iter->depth;
-                if (iter->depth == 0) {
+        void *next;
+        cx_tree_iter_search_next:
+        // check if there is a sibling
+        next = tree_next(iter->node);
+        if (next == NULL) {
+            // no sibling, we are done with this node and exit
+            if (iter->visit_on_exit && !iter->exiting) {
+                // iter is supposed to visit the node again
+                iter->exiting = true;
+            } else {
+                iter->exiting = false;
+                if (iter->depth == 1) {
                     // there is no parent - we have iterated the entire tree
                     // invalidate the iterator and free the node stack
                     iter->node = NULL;
-                    current = NULL;
-                    iter->stack_capacity = 0;
+                    iter->stack_capacity = iter->depth = 0;
                     free(iter->stack);
                     iter->stack = NULL;
                 } else {
                     // the parent node can be obtained from the top of stack
                     // this way we can avoid the loc_parent in the iterator
-                    current = iter->stack[iter->depth - 1];
+                    iter->depth--;
+                    iter->node = iter->stack[iter->depth - 1];
+                    // retry with the parent node to find a sibling
+                    goto cx_tree_iter_search_next;
                 }
+            }
+        } else {
+            if (iter->visit_on_exit && !iter->exiting) {
+                // iter is supposed to visit the node again
+                iter->exiting = true;
             } else {
-                // move to the sibling and break the loop
-                current = NULL;
+                iter->exiting = false;
+                // move to the sibling
                 iter->counter++;
                 iter->node = next;
                 // new top of stack is the sibling
                 iter->stack[iter->depth - 1] = next;
             }
-        } while (current != NULL);
+        }
     } else {
         // node has children, push the first child onto the stack and enter it
         cx_array_simple_add(iter->stack, children);