PlayMinetestServer/mods/inventorybags/sort_inventory_function.lua

-- This function ( sort_inventory(inv) ) was taken form the technic_chests mod 
-- https://github.com/minetest-mods/technic/blob/master/technic_chests/register.lua
-- License:
-- Copyright (C) 2012-2014 Maciej Kasatkin (RealBadAngel)
-- Technic chests code is licensed under the GNU LGPLv2+.

function inventorybags.sort_inventory(inv)
 	local inlist = inv:get_list("main")
 	local typecnt = {}
 	local typekeys = {}
 	for _, st in ipairs(inlist) do
 		if not st:is_empty() then
 			local n = st:get_name()
 			local w = st:get_wear()
 			local m = st:get_metadata()
 			local k = string.format("%s %05d %s", n, w, m)
 			if not typecnt[k] then
				typecnt[k] = {st}
 				table.insert(typekeys, k)
			else
				table.insert(typecnt[k], st)
 			end
 		end
 	end
 	table.sort(typekeys)
	inv:set_list("main", {})
 	for _, k in ipairs(typekeys) do
		for _, item in ipairs(typecnt[k]) do
			inv:add_item("main", item)
 		end
 	end
end