fix #221, avoid children attribute access on maxlevel

anytree/iterators/levelorderiter.py

@@ -40,11 +40,14 @@ def _iter(children, filter_, stop, maxlevel):
         level = 1
         while children:
             next_children = []
-            for child in children:
-                if filter_(child):
-                    yield child
-                next_children += AbstractIter._get_children(child.children, stop)
-            children = next_children
             level += 1
             if AbstractIter._abort_at_level(level, maxlevel):
-                break
+                for child in children:
+                    if filter_(child):
+                        yield child
+            else:
+                for child in children:
+                    if filter_(child):
+                        yield child
+                    next_children += AbstractIter._get_children(child.children, stop)
+            children = next_children

anytree/render.py

@@ -276,13 +276,14 @@ def __iter__(self):
 
     def __next(self, node, continues, level=0):
         yield RenderTree.__item(node, continues, self.style)
-        children = node.children
         level += 1
-        if children and (self.maxlevel is None or level < self.maxlevel):
-            children = self.childiter(children)
-            for child, is_last in _is_last(children):
-                for grandchild in self.__next(child, continues + (not is_last,), level=level):
-                    yield grandchild
+        if self.maxlevel is None or level < self.maxlevel:
+            children = node.children
+            if children:
+                children = self.childiter(children)
+                for child, is_last in _is_last(children):
+                    for grandchild in self.__next(child, continues + (not is_last,), level=level):
+                        yield grandchild
 
     @staticmethod
     def __item(node, continues, style):