1 files changed, 28 insertions, 25 deletions

diff --git a/util/set.lua b/util/set.lua
index e4cc2dff..89cd7cf3 100644
--- a/util/set.lua
+++ b/util/set.lua
@@ -1,7 +1,7 @@
 -- Prosody IM
 -- Copyright (C) 2008-2010 Matthew Wild
 -- Copyright (C) 2008-2010 Waqas Hussain
--- 
+--
 -- This project is MIT/X11 licensed. Please see the
 -- COPYING file in the source package for more information.
 --
@@ -26,8 +26,9 @@ function set_mt.__div(set, func)
 	local new_set, new_items = _M.new();
 	local items, new_items = set._items, new_set._items;
 	for item in pairs(items) do
-		if func(item) then
-			new_items[item] = true;
+		local new_item = func(item);
+		if new_item ~= nil then
+			new_items[new_item] = true;
 		end
 	end
 	return new_set;
@@ -39,13 +40,13 @@ function set_mt.__eq(set1, set2)
 			return false;
 		end
 	end
-	
+
 	for item in pairs(set2) do
 		if not set1[item] then
 			return false;
 		end
 	end
-	
+
 	return true;
 end
 function set_mt.__tostring(set)
@@ -64,56 +65,58 @@ end
 function new(list)
 	local items = setmetatable({}, items_mt);
 	local set = { _items = items };
-	
+
 	function set:add(item)
 		items[item] = true;
 	end
-	
+
 	function set:contains(item)
 		return items[item];
 	end
-	
+
 	function set:items()
-		return items;
+		return next, items;
 	end
-	
+
 	function set:remove(item)
 		items[item] = nil;
 	end
-	
+
 	function set:add_list(list)
-		for _, item in ipairs(list) do
-			items[item] = true;
+		if list then
+			for _, item in ipairs(list) do
+				items[item] = true;
+			end
 		end
 	end
-	
+
 	function set:include(otherset)
-		for item in pairs(otherset) do
+		for item in otherset do
 			items[item] = true;
 		end
 	end
 
 	function set:exclude(otherset)
-		for item in pairs(otherset) do
+		for item in otherset do
 			items[item] = nil;
 		end
 	end
-	
+
 	function set:empty()
 		return not next(items);
 	end
-	
+
 	if list then
 		set:add_list(list);
 	end
-	
+
 	return setmetatable(set, set_mt);
 end
 
 function union(set1, set2)
 	local set = new();
 	local items = set._items;
-	
+
 	for item in pairs(set1._items) do
 		items[item] = true;
 	end
@@ -121,14 +124,14 @@ function union(set1, set2)
 	for item in pairs(set2._items) do
 		items[item] = true;
 	end
-	
+
 	return set;
 end
 
 function difference(set1, set2)
 	local set = new();
 	local items = set._items;
-	
+
 	for item in pairs(set1._items) do
 		items[item] = (not set2._items[item]) or nil;
 	end
@@ -139,13 +142,13 @@ end
 function intersection(set1, set2)
 	local set = new();
 	local items = set._items;
-	
+
 	set1, set2 = set1._items, set2._items;
-	
+
 	for item in pairs(set1) do
 		items[item] = (not not set2[item]) or nil;
 	end
-	
+
 	return set;
 end