diff options
Diffstat (limited to 'tools/migration/mtools.lua')
| -rw-r--r-- | tools/migration/mtools.lua | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/tools/migration/mtools.lua b/tools/migration/mtools.lua new file mode 100644 index 00000000..d2bd1e7a --- /dev/null +++ b/tools/migration/mtools.lua @@ -0,0 +1,56 @@ +
+
+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;
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