Improve performance of Remove Empty Groups extension. Thanks to Cyrille

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extensions/fablabchemnitz/remove_empty_groups/remove_empty_groups.py

@@ -5,32 +5,40 @@ import inkex
 """
 Extension for InkScape 1.0
 
-This extension is totally minimal. It will just clean the whole document from groups without content (dangling groups). That usually happens if you have a group but remove it's paths for example. The group will possibly stay in the XML tree. This also applies for layers because layers are just special types of groups. This effect applies to the whole document ONLY!
+This extension is totally minimal. It will just clean the whole document from groups without content (dangling groups). That usually happens if you have a group but remove its paths for example. The group will possibly stay in the XML tree. This also applies for layers because layers are just special types of groups. This effect applies to the whole document ONLY!
  
 Author: Mario Voigt / FabLab Chemnitz
 Mail: mario.voigt@stadtfabrikanten.org
 Date: 19.08.2020
-Last Patch: 01.04.2021
+Last Patch: 18.04.2022
 License: GNU GPL v3
+
+Thanks to Cyrille
 """
 
 class RemoveEmptyGroups(inkex.EffectExtension):
      
     def effect(self):
-        while True: 
-            groups = self.document.xpath('//svg:g',namespaces=inkex.NSS)
-            oldLen = len(groups)
-            #leave the loop if there are no groups at all
-            if len(groups) == 0:
-                break
-            #loop trough groups. we have minimum of one to check for emptyness
-            for group in groups:
-                if len(group.getchildren()) == 0 and group.getparent() is not None:
-                    group.getparent().remove(group) #deletes the deepest empty group
-                    continue #we found minimum of one element to delete. so we should run another cycle to check if the parent of this group is empty after deletion
-            newLen = len(self.document.xpath('//svg:g',namespaces=inkex.NSS))
-            if newLen == oldLen: #found no more empty groups. Leaving the loop
-                break
-            
-if __name__ == '__main__':            
+        # gets all group elements in document, at any/all nested levels
+        groups = self.document.xpath('//svg:g',namespaces=inkex.NSS)
+
+        # end if there are no groups
+        if len(groups) == 0:
+            return
+
+        # used to track if we make changes
+        made_changes = False
+
+        # loop through groups
+        for group in groups:
+
+            # checks if item is empty leaf, and if so prune up branch
+            while len(group.getchildren()) == 0:
+                # this group is empty, delete it
+                parent = group.getparent()
+                parent.remove(group)
+                # see if we should delete the parent too, recursively
+                group = parent
+
+if __name__ == '__main__':
     RemoveEmptyGroups().run()