Add legacy node conversion to vl_legacy and update rails.lua to use it

mods/CORE/vl_legacy/API.md

@@ -17,3 +17,19 @@ Arguments:
 * `old`: Itemstring to be converted
 * `new`: New item string
 
+## `vl_legacy.convert_node(pos, node)`
+
+Converts legacy nodes to newer versions.
+
+Arguments:
+* `pos`: Position of the node to attempt conversion
+* `node`: Node definition to convert. The node will be loaded from map data if `nil`.
+
+The node definition for the old node must contain the field `_vl_legacy_convert` with
+a value that is either a `function(pos, node)` or `string` for this call to have any
+affect. If a function is provided, the function is called with `pos` and `node` as
+arguments. If a string is provided, a node name conversion will occur.
+
+This mod provides an LBM and ABM that will automatically call this function for nodes
+with `group:legacy` set.
+

mods/CORE/vl_legacy/init.lua

@@ -35,6 +35,17 @@ function mod.convert_inventory(inv)
 	mod.convert_inventory_lists(lists)
 	inv:set_lists(lists)
 end
+function mod.convert_node(pos, node)
+	local node = node or minetest.get_node(pos)
+	local node_def = minetest.registered_nodes[node.name]
+	local convert = node_def._vl_legacy_convert_node
+	if type(convert) == "function" then
+		convert(pos, node)
+	elseif type(convert) == "string" then
+		node.name = convert
+		minetest.swap_node(pos, node)
+	end
+end
 
 minetest.register_on_joinplayer(function(player)
 	mod.convert_inventory(player:get_inventory())
@@ -49,4 +60,16 @@ minetest.register_lbm({
 		mod.convert_inventory(meta:get_inventory())
 	end
 })
-
+minetest.register_lbm({
+	name = "vl_legacy:convert_nodes",
+	nodenames = "group:legacy",
+	run_at_every_load = true,
+	action = mod.convert_node,
+})
+minetest.register_abm({
+	label = "Convert Legacy Nodes",
+	nodenames = "group:legacy",
+	interval = 5,
+	chance = 1,
+	action = mod.convert_node,
+})

mods/ENTITIES/mcl_minecarts/rails.lua

@@ -373,28 +373,24 @@ end
 local CURVY_RAILS_MAP = {
 	["mcl_minecarts:rail"] = "mcl_minecarts:rail_v2",
 }
+local function convert_legacy_curvy_rails(pos, node)
+	node.name = CURVY_RAILS_MAP[node.name]
+	if node.name then
+		minetest.swap_node(pos, node)
+		mod.update_rail_connections(pos, { legacy = true, ignore_neighbor_connections = true })
+	end
+end
 for old,new in pairs(CURVY_RAILS_MAP) do
 	local new_def = minetest.registered_nodes[new]
 	minetest.register_node(old, {
 		drawtype = "raillike",
 		inventory_image = new_def.inventory_image,
-		groups = { rail = 1 },
+		groups = { rail = 1, legacy = 1 },
 		tiles = { new_def.tiles[1], new_def.tiles[1], new_def.tiles[1], new_def.tiles[1] },
+		_vl_legacy_convert_node = convert_legacy_curvy_rails
 	})
 	vl_legacy.register_item_conversion(old, new)
 end
-minetest.register_lbm({
-	name = "mcl_minecarts:update_legacy_curvy_rails",
-	nodenames = mcl_util.table_keys(CURVY_RAILS_MAP),
-	run_at_every_load = true,
-	action = function(pos, node)
-		node.name = CURVY_RAILS_MAP[node.name]
-		if node.name then
-			minetest.swap_node(pos, node)
-			mod.update_rail_connections(pos, { legacy = true, ignore_neighbor_connections = true })
-		end
-	end
-})
 local STRAIGHT_RAILS_MAP ={
 	["mcl_minecarts:golden_rail"] = "mcl_minecarts:golden_rail_v2",
 	["mcl_minecarts:golden_rail_on"] = "mcl_minecarts:golden_rail_v2_on",
@@ -403,39 +399,34 @@ local STRAIGHT_RAILS_MAP ={
 	["mcl_minecarts:detector_rail"] = "mcl_minecarts:detector_rail_v2",
 	["mcl_minecarts:detector_rail_on"] = "mcl_minecarts:detector_rail_v2_on",
 }
+local function convert_legacy_straight_rail(pos, node)
+	node.name = STRAIGHT_RAILS_MAP[node.name]
+	if node.name then
+		local connections = mod.get_rail_connections(pos, { legacy = true, ignore_neighbor_connections = true })
+		if not mod.HORIZONTAL_STANDARD_RULES[connections] then
+			-- Drop an immortal object at this location
+			local item_entity = minetest.add_item(pos, ItemStack(node.name))
+			if item_entity then
+				item_entity:get_luaentity()._immortal = true
+			end
+
+			-- This is a configuration that doesn't exist in the new rail
+			-- Replace with a standard rail
+			node.name = "mcl_minecarts:rail_v2"
+		end
+		minetest.swap_node(pos, node)
+		mod.update_rail_connections(pos, { legacy = true, ignore_neighbor_connections = true })
+	end
+end
 for old,new in pairs(STRAIGHT_RAILS_MAP) do
 	local new_def = minetest.registered_nodes[new]
 	minetest.register_node(old, {
 		drawtype = "raillike",
 		inventory_image = new_def.inventory_image,
-		groups = { rail = 1 },
+		groups = { rail = 1, legacy = 1 },
 		tiles = { new_def.tiles[1], new_def.tiles[1], new_def.tiles[1], new_def.tiles[1] },
+		_vl_legacy_convert_node = convert_legacy_straight_rail,
 	})
 	vl_legacy.register_item_conversion(old, new)
 end
 
-minetest.register_lbm({
-	name = "mcl_minecarts:update_legacy_straight_rails",
-	nodenames = mcl_util.table_keys(STRAIGHT_RAILS_MAP),
-	run_at_every_load = true,
-	action = function(pos, node)
-		node.name = STRAIGHT_RAILS_MAP[node.name]
-		if node.name then
-			local connections = mod.get_rail_connections(pos, { legacy = true, ignore_neighbor_connections = true })
-			if not mod.HORIZONTAL_STANDARD_RULES[connections] then
-				-- Drop an immortal object at this location
-				local item_entity = minetest.add_item(pos, ItemStack(node.name))
-				if item_entity then
-					item_entity:get_luaentity()._immortal = true
-				end
-
-				-- This is a configuration that doesn't exist in the new rail
-				-- Replace with a standard rail
-				node.name = "mcl_minecarts:rail_v2"
-			end
-			minetest.swap_node(pos, node)
-			mod.update_rail_connections(pos, { legacy = true, ignore_neighbor_connections = true })
-		end
-	end
-})
-