aboutsummaryrefslogtreecommitdiffstats
path: root/tools/migration/migrator/mtools.lua
blob: e7b774bbc82700e21e77009719b7f01e33b571d4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56


local print = print;
local t_insert = table.insert;
local t_sort = table.sort;

module "mtools"

function sorted(params)

	local reader = params.reader; -- iterator to get items from
	local sorter = params.sorter; -- sorting function
	local filter = params.filter; -- filter function

	local cache = {};
	for item in reader do
		if filter then item = filter(item); end
		if item then t_insert(cache, item); end
	end
	if sorter then
		t_sort(cache, sorter);
	end
	local i = 0;
	return function()
		i = i + 1;
		return cache[i];
	end;

end

function merged(reader, merger)

	local item1 = reader();
	local merged = { item1 };
	return function()
		while true do
			if not item1 then return nil; end
			local item2 = reader();
			if not item2 then item1 = nil; return merged; end
			if merger(item1, item2) then
			--print("merged")
				item1 = item2;
				t_insert(merged, item1);
			else
			--print("unmerged", merged)
				item1 = item2;
				local tmp = merged;
				merged = { item1 };
				return tmp;
			end
		end
	end;

end

return _M;