-local ipairs, pairs =
- ipairs, pairs;
+-- 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, 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;
+ 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 };
+ local items = setmetatable({}, items_mt);
+ local set = { _items = items };
function set:add(item)
items[item] = true;
end
end
+ function set:empty()
+ return not next(items);
+ end
+
if list then
set:add_list(list);
end
- return set;
+ return setmetatable(set, set_mt);
end
function union(set1, set2)
local set = new();
- local items = set.items;
+ local items = set._items;
- for item in pairs(set1.items) do
+ 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
function difference(set1, set2)
local set = new();
- local items = set.items;
+ local items = set._items;
- for item in pairs(set1.items) do
- items[item] = true;
+ 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;