From 34a4b98cf6dbb4a97dda590d16832ffcd196bd3a Mon Sep 17 00:00:00 2001
From: Matthew Wild <mwild1@gmail.com>
Date: Wed, 22 Apr 2009 18:00:45 +0100
Subject: util.set: Add metatable to sets to allow +, -, /, ==, tostring and to
 double as iterators

---
 util/set.lua | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 54 insertions(+), 4 deletions(-)

(limited to 'util/set.lua')

diff --git a/util/set.lua b/util/set.lua
index f550a721..892f1c9d 100644
--- a/util/set.lua
+++ b/util/set.lua
@@ -1,10 +1,60 @@
-local ipairs, pairs = 
-      ipairs, pairs;
+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 items = setmetatable({}, items_mt);
 	local set = { _items = items };
 	
 	function set:add(item)
@@ -45,7 +95,7 @@ function new(list)
 		set:add_list(list);
 	end
 	
-	return set;
+	return setmetatable(set, set_mt);
 end
 
 function union(set1, set2)
-- 
cgit v1.2.3


From 901af1535f708d391d10e7c116d4a9538b89dac2 Mon Sep 17 00:00:00 2001
From: Matthew Wild <mwild1@gmail.com>
Date: Wed, 22 Apr 2009 18:03:02 +0100
Subject: util.set: Add set:empty() to discover if the set is the empty set

---
 util/set.lua | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'util/set.lua')

diff --git a/util/set.lua b/util/set.lua
index 892f1c9d..bb318adf 100644
--- a/util/set.lua
+++ b/util/set.lua
@@ -91,6 +91,10 @@ function new(list)
 		end
 	end
 	
+	function set:empty()
+		return not next(items);
+	end
+	
 	if list then
 		set:add_list(list);
 	end
-- 
cgit v1.2.3


From 0d98ee54b5a332e5d6a42aebf85026da2d432d2f Mon Sep 17 00:00:00 2001
From: Matthew Wild <mwild1@gmail.com>
Date: Wed, 22 Apr 2009 18:03:42 +0100
Subject: util.set: Add set.xor() to get a set consisting of items not in both
 sets

---
 util/set.lua | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'util/set.lua')

diff --git a/util/set.lua b/util/set.lua
index bb318adf..84bfe8c4 100644
--- a/util/set.lua
+++ b/util/set.lua
@@ -141,4 +141,8 @@ function intersection(set1, set2)
 	return set;
 end
 
+function xor(set1, set2)
+	return union(set1, set2) - intersection(set1, set2);
+end
+
 return _M;
-- 
cgit v1.2.3