prosody
594a07e753a0
util/set.lua

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util/set.lua @ 1028:594a07e753a0

util.set: Add metatable to sets to allow +, -, /, ==, tostring and to double as iterators
author Matthew Wild <mwild1@gmail.com>
date Wed, 22 Apr 2009 18:00:45 +0100
parent 917:f12f88b3d4a1
child 1029:4ead03974759
comparison
equal deleted inserted replaced
1027:fe2e3d3dba6a 1028:594a07e753a0
1 local ipairs, pairs = 1 local ipairs, pairs, setmetatable, next, tostring =
2 ipairs, pairs; 2 ipairs, pairs, setmetatable, next, tostring;
3 local t_concat = table.concat;
3 4
4 module "set" 5 module "set"
5 6
7 local set_mt = {};
8 function set_mt.__call(set, _, k)
9 return next(set._items, k);
10 end
11 function set_mt.__add(set1, set2)
12 return _M.union(set1, set2);
13 end
14 function set_mt.__sub(set1, set2)
15 return _M.difference(set1, set2);
16 end
17 function set_mt.__div(set, func)
18 local new_set, new_items = _M.new();
19 local items, new_items = set._items, new_set._items;
20 for item in pairs(items) do
21 if func(item) then
22 new_items[item] = true;
23 end
24 end
25 return new_set;
26 end
27 function set_mt.__eq(set1, set2)
28 local set1, set2 = set1._items, set2._items;
29 for item in pairs(set1) do
30 if not set2[item] then
31 return false;
32 end
33 end
34
35 for item in pairs(set2) do
36 if not set1[item] then
37 return false;
38 end
39 end
40
41 return true;
42 end
43 function set_mt.__tostring(set)
44 local s, items = { }, set._items;
45 for item in pairs(items) do
46 s[#s+1] = tostring(item);
47 end
48 return t_concat(s, ", ");
49 end
50
51 local items_mt = {};
52 function items_mt.__call(items, _, k)
53 return next(items, k);
54 end
55
6 function new(list) 56 function new(list)
7 local items = {}; 57 local items = setmetatable({}, items_mt);
8 local set = { _items = items }; 58 local set = { _items = items };
9 59
10 function set:add(item) 60 function set:add(item)
11 items[item] = true; 61 items[item] = true;
12 end 62 end
43 93
44 if list then 94 if list then
45 set:add_list(list); 95 set:add_list(list);
46 end 96 end
47 97
48 return set; 98 return setmetatable(set, set_mt);
49 end 99 end
50 100
51 function union(set1, set2) 101 function union(set1, set2)
52 local set = new(); 102 local set = new();
53 local items = set._items; 103 local items = set._items;