mod_adhoc: Add support for commands only executable by global administrators

[prosody.git] / util / set.lua

diff --git a/util/set.lua b/util/set.lua
index 892f1c9d3f70e14bc75a3d36df9ebdcd98531078..e4cc2dffbd428b6be84c2ec749ba0cd2156b67b3 100644 (file)
--- a/util/set.lua
+++ b/util/set.lua
@@ -1,4 +1,12 @@
-local ipairs, pairs, setmetatable, next, tostring = 
+-- 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.
+--
+
+local ipairs, pairs, setmetatable, next, tostring =
       ipairs, pairs, setmetatable, next, tostring;
 local t_concat = table.concat;
 
@@ -91,6 +99,10 @@ function new(list)
                end
        end
        
+       function set:empty()
+               return not next(items);
+       end
+       
        if list then
                set:add_list(list);
        end
@@ -137,4 +149,8 @@ function intersection(set1, set2)
        return set;
 end
 
+function xor(set1, set2)
+       return union(set1, set2) - intersection(set1, set2);
+end
+
 return _M;