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[prosody.git] / util / set.lua

diff --git a/util/set.lua b/util/set.lua
index 08361d03332044e929bd01ed998f4391c83f8c5c..04f5f0f4f297d3d5b9d8bf3d167edebf4cf6d092 100644 (file)
--- a/util/set.lua
+++ b/util/set.lua
@@ -1,75 +1,159 @@
+-- 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;
 
 module "set"
 
+local set_mt = {};
+function set_mt.__call(set, _, k)
+       return next(set._items, k);
+end
+function set_mt.__add(set1, set2)
+       return _M.union(set1, set2);
+end
+function set_mt.__sub(set1, set2)
+       return _M.difference(set1, set2);
+end
+function set_mt.__div(set, func)
+       local new_set = _M.new();
+       local items, new_items = set._items, new_set._items;
+       for item in pairs(items) do
+               local new_item = func(item);
+               if new_item ~= nil then
+                       new_items[new_item] = true;
+               end
+       end
+       return new_set;
+end
+function set_mt.__eq(set1, set2)
+       local set1, set2 = set1._items, set2._items;
+       for item in pairs(set1) do
+               if not set2[item] then
+                       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)
+       local s, items = { }, set._items;
+       for item in pairs(items) do
+               s[#s+1] = tostring(item);
+       end
+       return t_concat(s, ", ");
+end
+
+local items_mt = {};
+function items_mt.__call(items, _, k)
+       return next(items, k);
+end
+
 function new(list)
-       local items = {};
-       local set = { items = items };
-       
-       function set:add(set, item)
+       local items = setmetatable({}, items_mt);
+       local set = { _items = items };
+
+       function set:add(item)
                items[item] = true;
        end
-       
-       function set:contains(set, item)
-               return items[item]
+
+       function set:contains(item)
+               return items[item];
        end
-       
-       function set:items(set)
-               return items;
+
+       function set:items()
+               return next, items;
        end
-       
-       function set:remove(set, item)
+
+       function set:remove(item)
                items[item] = nil;
        end
-       
-       function set:add_list(set, list)
-               for _, item in ipairs(list) do
-                       items[item] = true;
+
+       function set:add_list(list)
+               if list then
+                       for _, item in ipairs(list) do
+                               items[item] = true;
+                       end
                end
        end
-       
-       function set:include(set, otherset)
-               for item in pairs(otherset) do
+
+       function set:include(otherset)
+               for item in otherset do
                        items[item] = true;
                end
        end
 
-       function set:exclude(set, otherset)
-               for item in pairs(otherset) do
+       function set:exclude(otherset)
+               for item in otherset do
                        items[item] = nil;
                end
        end
-       
-       return set;
+
+       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
+       local items = set._items;
+
+       for item in pairs(set1._items) do
                items[item] = true;
        end
 
-       for item in pairs(set2.items) do
+       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] = true;
+       local items = set._items;
+
+       for item in pairs(set1._items) do
+               items[item] = (not set2._items[item]) or nil;
        end
 
-       for item in pairs(set2.items) do
-               items[item] = nil;
+       return set;
+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
 
+function xor(set1, set2)
+       return union(set1, set2) - intersection(set1, set2);
+end
+
 return _M;