tools/migration/migrator/mtools.lua

   1
   2
   3 local print = print;
   4 local t_insert = table.insert;
   5 local t_sort = table.sort;
   6
   7 module "mtools"
   8
   9 function sorted(params)
  10
  11         local reader = params.reader; -- iterator to get items from
  12         local sorter = params.sorter; -- sorting function
  13         local filter = params.filter; -- filter function
  14
  15         local cache = {};
  16         for item in reader do
  17                 if filter then item = filter(item); end
  18                 if item then t_insert(cache, item); end
  19         end
  20         if sorter then
  21                 t_sort(cache, sorter);
  22         end
  23         local i = 0;
  24         return function()
  25                 i = i + 1;
  26                 return cache[i];
  27         end;
  28
  29 end
  30
  31 function merged(reader, merger)
  32
  33         local item1 = reader();
  34         local merged = { item1 };
  35         return function()
  36                 while true do
  37                         if not item1 then return nil; end
  38                         local item2 = reader();
  39                         if not item2 then item1 = nil; return merged; end
  40                         if merger(item1, item2) then
  41                         --print("merged")
  42                                 item1 = item2;
  43                                 t_insert(merged, item1);
  44                         else
  45                         --print("unmerged", merged)
  46                                 item1 = item2;
  47                                 local tmp = merged;
  48                                 merged = { item1 };
  49                                 return tmp;
  50                         end
  51                 end
  52         end;
  53
  54 end
  55
  56 return _M;