1 files changed, 159 insertions, 0 deletions
diff --git a/util/set.lua b/util/set.lua
new file mode 100644
index 00000000..7f45526e
--- /dev/null
+++ b/util/set.lua
@@ -0,0 +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, new_items = _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 = 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;
+	end
+	
+	function set:remove(item)
+		items[item] = nil;
+	end
+	
+	function set:add_list(list)
+		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
+			items[item] = true;
+		end
+	end
+
+	function set:exclude(otherset)
+		for item in pairs(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
+
+	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
+
+	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;