Question

Anybody have a slicker way to do this? Seems like it should be easier than this, but I’m having a mental block. Basically I need to remove items from an dictionary and recurse into the values of the items that are also dictionaries.

private void RemoveNotPermittedItems(ActionDictionary menu) {     var keysToRemove = new List<string>();     foreach (var item in menu)     {         if (!GetIsPermitted(item.Value.Call))         {             keysToRemove.Add(item.Key);         }         else if (item.Value is ActionDictionary)         {             RemoveNotPermittedItems((ActionDictionary)item.Value);             if (((ActionDictionary)item.Value).Count == 0)             {                 keysToRemove.Add(item.Key);             }         }     }     foreach (var key in (from item in menu where keysToRemove.Contains(item.Key) select item.Key).ToArray())     {         menu.Remove(key);     } } 

Action dictionary is like this:

public class ActionDictionary : Dictionary<string, IActionItem>, IActionItem 

Answer 1

You don’t really need to collect the keys and iterate them again if you iterate the dictionary in reverse (from ‘menu.Count – 1’ to zero). Iterating in forward order will, of course, yield mutated collection exceptions if you start removing things.

I don’t know what an ActionDictionary is, so I couldn’t test your exact scenario, but here’s an example using just Dictionary<string,object>.

    static int counter = 0;     private static void RemoveNotPermittedItems(Dictionary<string, object> menu)     {         for (int c = menu.Count - 1; c >= 0; c--)         {             var key = menu.Keys.ElementAt(c);             var value = menu[key];             if (value is Dictionary<string, object>)             {                 RemoveNotPermittedItems((Dictionary<string, object>)value);                 if (((Dictionary<string, object>)value).Count == 0)                 {                     menu.Remove(key);                 }             }             else if (!GetIsPermitted(value))             {                 menu.Remove(key);             }         }     }      // This just added to actually cause some elements to be removed...     private static bool GetIsPermitted(object value)     {         if (counter++ % 2 == 0)             return false;         return true;     } 

I also reversed the ‘if’ statement, but that was just an assumption that you’d want to do type checking before calling a method to act on the item’s value…it will work either way assuming ‘GetIsPermitted’ always returns TRUE for ActionDictionary.

Hope this helps.