Refactor write_config() a bit

Since the 'top_node' menu node itself is skipped, we can start from
there and move the tree walk to the beginning of the loop. For an empty
configuration (top_node.list set to None) the tree walk immediately
discovers that there are no more nodes and returns.

1 files changed, 19 insertions, 19 deletions

diff --git a/kconfiglib.py b/kconfiglib.py
index 5aaedcc..a01df27 100644
--- a/kconfiglib.py
+++ b/kconfiglib.py
@@ -1090,26 +1090,11 @@ class Kconfig(object):
             for sym in self._defined_syms_set:
                 sym._written = False
 
-            node = self.top_node.list
-            if not node:
-                # Empty configuration
-                return
-
+            # The 'top_node' menu node itself doesn't generate any output, so
+            # it's skipped over below
+            node = self.top_node
             while 1:
-                item = node.item
-                if isinstance(item, Symbol):
-                    if not item._written:
-                        item._written = True
-                        f.write(item.config_string)
-
-                elif expr_value(node.dep) and \
-                     ((item == MENU and expr_value(node.visibility)) or
-                       item == COMMENT):
-
-                    f.write("\n#\n# {}\n#\n".format(node.prompt[0]))
-
-                # Iterative tree walk using parent pointers
-
+                # Jump to the next node with an iterative tree walk
                 if node.list:
                     node = node.list
                 elif node.next:
@@ -1123,6 +1108,21 @@ class Kconfig(object):
                     else:
                         return
 
+                # Write node
+
+                item = node.item
+
+                if isinstance(item, Symbol):
+                    if not item._written:
+                        item._written = True
+                        f.write(item.config_string)
+
+                elif expr_value(node.dep) and \
+                     ((item == MENU and expr_value(node.visibility)) or
+                       item == COMMENT):
+
+                    f.write("\n#\n# {}\n#\n".format(node.prompt[0]))
+
     def write_min_config(self, filename,
                          header="# Generated by Kconfiglib (https://github.com/ulfalizer/Kconfiglib)\n"):
         """