Get rid of deprecated metadata (#628)

The deprecated metadata gets converted to a proper ItemStackMetaRef.
All keys stay the same except for:
- Cans that use `can_level` now, since they didn't store a serialized table in the metadata before.
- `charge` which is now `technic:charge`, since any item (also from other mods) may have a technic charge which can cause compatibility problems.

Backwards compatibility is kept but going back to older `technic` versions might result in misbehaving circuits.

technic/helpers.lua

@@ -65,15 +65,26 @@ function technic.swap_node(pos, name)
 end
 
 
+--- Returns the meta of an item
+-- Gets overridden when legacy.lua is loaded
+function technic.get_stack_meta(itemstack)
+	return itemstack:get_meta()
+end
+
+--- Same as technic.get_stack_meta for cans
+function technic.get_stack_meta_cans(itemstack)
+	return itemstack:get_meta()
+end
+
+
 --- Fully charge RE chargeable item.
 -- Must be defined early to reference in item definitions.
 function technic.refill_RE_charge(stack)
 	local max_charge = technic.power_tools[stack:get_name()]
 	if not max_charge then return stack end
+	local meta = technic.get_stack_meta(stack)
+	meta:set_int("technic:charge", max_charge)
 	technic.set_RE_wear(stack, max_charge, max_charge)
-	local meta = minetest.deserialize(stack:get_metadata()) or {}
-	meta.charge = max_charge
-	stack:set_metadata(minetest.serialize(meta))
 	return stack
 end
 

technic/legacy.lua

@@ -39,3 +39,40 @@ for i = 0, 64 do
 	minetest.register_alias("technic:lv_cable"..i, "technic:lv_cable")
 end
 
+-- Item meta
+
+-- Meta keys that have changed
+technic.legacy_meta_keys = {
+	["charge"] = "technic:charge",
+}
+
+-- Converts legacy itemstack metadata string to itemstack meta and returns the ItemStackMetaRef
+function technic.get_stack_meta(itemstack)
+	local meta = itemstack:get_meta()
+	local legacy_string = meta:get("") -- Get deprecated metadata
+	if legacy_string then
+		local legacy_table = minetest.deserialize(legacy_string)
+		if legacy_table then
+			local table = meta:to_table()
+			for k, v in pairs(legacy_table) do
+				table.fields[technic.legacy_meta_keys[k] or k] = v
+			end
+			meta:from_table(table)
+		end
+		meta:set_string("", "") -- Remove deprecated metadata
+	end
+	return meta
+end
+
+-- Same as technic.get_stack_meta for cans.
+-- (Cans didn't store a serialized table in the legacy metadata string, but just a number.)
+function technic.get_stack_meta_cans(itemstack)
+	local meta = itemstack:get_meta()
+	local legacy_string = meta:get("") -- Get deprecated metadata
+	if legacy_string then
+		meta:set_string("can_level", legacy_string)
+		meta:set_string("", "") -- Remove deprecated metadata
+		return meta
+	end
+	return meta
+end

technic/machines/register/battery_box.lua

@@ -415,22 +415,17 @@ local function default_get_charge(itemstack)
 	if not technic.power_tools[tool_name] then
 		return 0, 0
 	end
-	-- Set meta data for the tool if it didn't do it itself
-	local item_meta = minetest.deserialize(itemstack:get_metadata()) or {}
-	if not item_meta.charge then
-		item_meta.charge = 0
-	end
-	return item_meta.charge, technic.power_tools[tool_name]
+	local item_meta = technic.get_stack_meta(itemstack)
+	return item_meta:get_int("technic:charge"), technic.power_tools[tool_name]
 end
 
 local function default_set_charge(itemstack, charge)
 	local tool_name = itemstack:get_name()
 	if technic.power_tools[tool_name] then
 		technic.set_RE_wear(itemstack, charge, technic.power_tools[tool_name])
 	end
-	local item_meta = minetest.deserialize(itemstack:get_metadata()) or {}
-	item_meta.charge = charge
-	itemstack:set_metadata(minetest.serialize(item_meta))
+	local item_meta = technic.get_stack_meta(itemstack)
+	item_meta:set_int("technic:charge", charge)
 end
 
 function technic.charge_tools(meta, batt_charge, charge_step)

technic/tools/cans.lua

@@ -12,14 +12,6 @@ local function set_can_wear(itemstack, level, max_level)
 	itemstack:set_wear(temp)
 end
 
-local function get_can_level(itemstack)
-	if itemstack:get_metadata() == "" then
-		return 0
-	else
-		return tonumber(itemstack:get_metadata())
-	end
-end
-
 function technic.register_can(d)
 	local data = {}
 	for k, v in pairs(d) do data[k] = v end
@@ -33,7 +25,8 @@ function technic.register_can(d)
 			if pointed_thing.type ~= "node" then return end
 			local node = minetest.get_node(pointed_thing.under)
 			if node.name ~= data.liquid_source_name then return end
-			local charge = get_can_level(itemstack)
+			local meta = technic.get_stack_meta_cans(itemstack)
+			local charge = meta:get_int("can_level")
 			if charge == data.can_capacity then return end
 			if minetest.is_protected(pointed_thing.under, user:get_player_name()) then
 				minetest.log("action", user:get_player_name()..
@@ -44,7 +37,7 @@ function technic.register_can(d)
 			end
 			minetest.remove_node(pointed_thing.under)
 			charge = charge + 1
-			itemstack:set_metadata(tostring(charge))
+			meta:set_int("can_level", charge)
 			set_can_wear(itemstack, charge, data.can_capacity)
 			return itemstack
 		end,
@@ -63,7 +56,8 @@ function technic.register_can(d)
 				-- Try to place node above the pointed source, or abort.
 				if not def.buildable_to or node_name == data.liquid_source_name then return end
 			end
-			local charge = get_can_level(itemstack)
+			local meta = technic.get_stack_meta_cans(itemstack)
+			local charge = meta:get_int("can_level")
 			if charge == 0 then return end
 			if minetest.is_protected(pos, user:get_player_name()) then
 				minetest.log("action", user:get_player_name()..
@@ -74,12 +68,13 @@ function technic.register_can(d)
 			end
 			minetest.set_node(pos, {name=data.liquid_source_name})
 			charge = charge - 1
-			itemstack:set_metadata(tostring(charge))
+			meta:set_int("can_level", charge)
 			set_can_wear(itemstack, charge, data.can_capacity)
 			return itemstack
 		end,
 		on_refill = function(stack)
-			stack:set_metadata(tostring(data.can_capacity))
+			local meta = technic.get_stack_meta_cans(stack)
+			meta:set_int("can_level", data.can_capacity)
 			set_can_wear(stack, data.can_capacity, data.can_capacity)
 			return stack
 		end,

technic/tools/chainsaw.lua

@@ -313,10 +313,8 @@ minetest.register_tool("technic:chainsaw", {
 			return itemstack
 		end
 
-		local meta = minetest.deserialize(itemstack:get_metadata())
-		if not meta or not meta.charge then
-			return
-		end
+		local meta = technic.get_stack_meta(itemstack)
+		local charge = meta:get_int("technic:charge")
 
 		local name = user:get_player_name()
 		if minetest.is_protected(pointed_thing.under, name) then
@@ -326,14 +324,14 @@ minetest.register_tool("technic:chainsaw", {
 
 		-- Send current charge to digging function so that the
 		-- chainsaw will stop after digging a number of nodes
-		chainsaw_dig(user, pointed_thing.under, meta.charge)
-		meta.charge = cutter.charge
+		chainsaw_dig(user, pointed_thing.under, charge)
+		charge = cutter.charge
 
 		cutter = {} -- Free RAM
 
 		if not technic.creative_mode then
-			technic.set_RE_wear(itemstack, meta.charge, chainsaw_max_charge)
-			itemstack:set_metadata(minetest.serialize(meta))
+			meta:set_int("technic:charge", charge)
+			technic.set_RE_wear(itemstack, charge, chainsaw_max_charge)
 		end
 		return itemstack
 	end,

technic/tools/flashlight.lua

@@ -38,12 +38,13 @@ local function check_for_flashlight(player)
 	local hotbar = inv:get_list("main")
 	for i = 1, 8 do
 		if hotbar[i]:get_name() == "technic:flashlight" then
-			local meta = minetest.deserialize(hotbar[i]:get_metadata())
-			if meta and meta.charge and meta.charge >= 2 then
+			local meta = technic.get_stack_meta(hotbar[i])
+			local charge = meta:get_int("technic:charge")
+			if charge >= 2 then
 				if not technic.creative_mode then
-					meta.charge = meta.charge - 2;
-					technic.set_RE_wear(hotbar[i], meta.charge, flashlight_max_charge)
-					hotbar[i]:set_metadata(minetest.serialize(meta))
+					charge = charge - 2;
+					meta:set_int("technic:charge", charge)
+					technic.set_RE_wear(hotbar[i], charge, flashlight_max_charge)
 					inv:set_stack("main", i, hotbar[i])
 				end
 				return true

technic/tools/mining_drill.lua

@@ -248,54 +248,53 @@ end
 
 local function mining_drill_mkX_setmode(user, itemstack, drill_type, max_modes)
 	local player_name = user:get_player_name()
-	local meta = minetest.deserialize(itemstack:get_metadata()) or {}
+	local meta = technic.get_stack_meta(itemstack)
 
-	if not meta["mode"] then
+	if not meta:contains("mode") then
 		minetest.chat_send_player(player_name,
 			S("Use while sneaking to change Mining Drill Mk%d modes."):format(drill_type))
 	end
-	local mode = (meta["mode"] or 0) + 1
+	local mode = meta:get_int("mode") + 1
 	if mode > max_modes then mode = 1 end
 
 	minetest.chat_send_player(player_name,
 		S("Mining Drill Mk%d Mode %d"):format(2, mode)..
 		": "..mining_drill_mode_text[mode][1])
     itemstack:set_name(("technic:mining_drill_mk%d_%s"):format(drill_type, mode))
-	meta["mode"] = mode
-    itemstack:set_metadata(minetest.serialize(meta))
+	meta:set_int("mode", mode)
 	return itemstack
 end
 
 local function mining_drill_mkX_handler(itemstack, user, pointed_thing, drill_type, max_modes)
 	local keys = user:get_player_control()
-	local meta = minetest.deserialize(itemstack:get_metadata()) or {}
+	local meta = technic.get_stack_meta(itemstack)
 
 	-- Mode switching (if possible)
 	if max_modes > 1 then
-		if not meta.mode or keys.sneak then
+		if not meta:contains("mode") or keys.sneak then
 			return mining_drill_mkX_setmode(user, itemstack, drill_type, max_modes)
 		end
 	end
 	if pointed_thing.type ~= "node" or not pos_is_pointable(pointed_thing.under) then
 		return
 	end
-	if not meta.charge then
-		return
-	end
+
+	local charge = meta:get_int("technic:charge")
+	local mode = meta:contains("mode") and meta:get_int("mode") or 1
 
 	-- Check whether the tool has enough charge
-	local charge_to_take = cost_to_use(drill_type, meta.mode or 1)
-	if meta.charge < charge_to_take then
+	local charge_to_take = cost_to_use(drill_type, mode)
+	if charge < charge_to_take then
 		return
 	end
 
 	-- Do the actual shoorting action
 	local pos = minetest.get_pointed_thing_position(pointed_thing, false)
-	drill_dig_it(pos, user, meta.mode or 1)
+	drill_dig_it(pos, user, mode)
 	if not technic.creative_mode then
-		meta.charge = meta.charge - charge_to_take
-		itemstack:set_metadata(minetest.serialize(meta))
-		technic.set_RE_wear(itemstack, meta.charge, max_charge[drill_type])
+		charge = charge - charge_to_take
+		meta:set_int("technic:charge", charge)
+		technic.set_RE_wear(itemstack, charge, max_charge[drill_type])
 	end
 	return itemstack
 end

technic/tools/mining_lasers.lua

@@ -101,25 +101,26 @@ for _, m in pairs(mining_lasers_list) do
 		wear_represents = "technic_RE_charge",
 		on_refill = technic.refill_RE_charge,
 		on_use = function(itemstack, user)
-			local meta = minetest.deserialize(itemstack:get_metadata())
-			if not meta or not meta.charge or meta.charge == 0 then
+			local meta = technic.get_stack_meta(itemstack)
+			local charge = meta:get_int("technic:charge")
+			if charge == 0 then
 				return
 			end
 
 			local range = m[2]
-			if meta.charge < m[4] then
+			if charge < m[4] then
 				if not allow_entire_discharging then
 					return
 				end
 				-- If charge is too low, give the laser a shorter range
-				range = range * meta.charge / m[4]
+				range = range * charge / m[4]
 			end
 			laser_shoot(user, range, "technic_laser_beam_mk" .. m[1] .. ".png",
 				"technic_laser_mk" .. m[1])
 			if not technic.creative_mode then
-				meta.charge = math.max(meta.charge - m[4], 0)
-				technic.set_RE_wear(itemstack, meta.charge, m[3])
-				itemstack:set_metadata(minetest.serialize(meta))
+				charge = math.max(charge - m[4], 0)
+				meta:set_int("technic:charge", charge)
+				technic.set_RE_wear(itemstack, charge, m[3])
 			end
 			return itemstack
 		end,

technic/tools/prospector.lua

@@ -2,14 +2,16 @@ local S = technic.getter
 
 technic.register_power_tool("technic:prospector", 300000)
 
-local function get_metadata(toolstack)
-	local m = minetest.deserialize(toolstack:get_metadata())
-	if not m then m = {} end
-	if not m.charge then m.charge = 0 end
-	if not m.target then m.target = "" end
-	if not m.look_depth then m.look_depth = 7 end
-	if not m.look_radius then m.look_radius = 1 end
-	return m
+-- Helper function to consolidate ItemStackMetaRef access and initialize
+local function meta_to_table(meta)
+	local t = {}
+	local mt = meta:to_table()
+
+	t.charge = tonumber(mt.fields["technic:charge"]) or 0
+	t.target = mt.fields.target or ""
+	t.look_depth = tonumber(mt.fields.look_depth) or 7
+	t.look_radius = tonumber(mt.fields.look_radius) or 1
+	return t
 end
 
 minetest.register_tool("technic:prospector", {
@@ -20,7 +22,8 @@ minetest.register_tool("technic:prospector", {
 	on_use = function(toolstack, user, pointed_thing)
 		if not user or not user:is_player() or user.is_fake_player then return end
 		if pointed_thing.type ~= "node" then return end
-		local toolmeta = get_metadata(toolstack)
+		local meta = technic.get_stack_meta(toolstack)
+		local toolmeta = meta_to_table(meta)
 		local look_diameter = toolmeta.look_radius * 2 + 1
 		local charge_to_take = toolmeta.look_depth * (toolmeta.look_depth + 1) * look_diameter * look_diameter
 		if toolmeta.charge < charge_to_take then return end
@@ -30,7 +33,7 @@ minetest.register_tool("technic:prospector", {
 		end
 		if not technic.creative_mode then
 			toolmeta.charge = toolmeta.charge - charge_to_take
-			toolstack:set_metadata(minetest.serialize(toolmeta))
+			meta:set_int("technic:charge", toolmeta.charge)
 			technic.set_RE_wear(toolstack, toolmeta.charge, technic.power_tools[toolstack:get_name()])
 		end
 		-- What in the heaven's name is this evil sorcery ?
@@ -77,7 +80,8 @@ minetest.register_tool("technic:prospector", {
 	end,
 	on_place = function(toolstack, user, pointed_thing)
 		if not user or not user:is_player() or user.is_fake_player then return end
-		local toolmeta = get_metadata(toolstack)
+		local meta = technic.get_stack_meta(toolstack)
+		local toolmeta = meta_to_table(meta)
 		local pointed
 		if pointed_thing.type == "node" then
 			local pname = minetest.get_node(pointed_thing.under).name
@@ -125,19 +129,16 @@ minetest.register_on_player_receive_fields(function(user, formname, fields)
 	if not user or not user:is_player() or user.is_fake_player then return end
 	local toolstack = user:get_wielded_item()
 	if toolstack:get_name() ~= "technic:prospector" then return true end
-	local toolmeta = get_metadata(toolstack)
+	local meta = technic.get_stack_meta(toolstack)
 	for field, value in pairs(fields) do
 		if field:sub(1, 7) == "target_" then
-			toolmeta.target = field:sub(8)
-		end
-		if field:sub(1, 12) == "look_radius_" then
-			toolmeta.look_radius = field:sub(13)
-		end
-		if field:sub(1, 11) == "look_depth_" then
-			toolmeta.look_depth = field:sub(12)
+			meta:set_string("target", field:sub(8))
+		elseif field:sub(1, 12) == "look_radius_" then
+			meta:set_string("look_radius", field:sub(13))
+		elseif field:sub(1, 11) == "look_depth_" then
+			meta:set_string("look_depth", field:sub(12))
 		end
 	end
-	toolstack:set_metadata(minetest.serialize(toolmeta))
 	user:set_wielded_item(toolstack)
 	return true
 end)