Don't require a full network recalculation to add or remove a dead end

A dead end (node with only one connection) can be simply added or removed from the network without needing to traverse the whole thing.

technic/machines/register/cables.lua

@@ -11,7 +11,15 @@ function technic.get_cable_tier(name)
 	return cable_tier[name]
 end
 
-local function clear_networks(pos)
+local function check_connections(pos)
+	-- Build a table of all machines
+	local machines = {}
+	for tier,list in pairs(technic.machines) do
+		for k,v in pairs(list) do
+			machines[k] = v
+		end
+	end
+	local connections = {}
 	local positions = {
 		{x=pos.x+1, y=pos.y,   z=pos.z},
 		{x=pos.x-1, y=pos.y,   z=pos.z},
@@ -19,9 +27,86 @@ local function clear_networks(pos)
 		{x=pos.x,   y=pos.y-1, z=pos.z},
 		{x=pos.x,   y=pos.y,   z=pos.z+1},
 		{x=pos.x,   y=pos.y,   z=pos.z-1}}
+	for _,connected_pos in pairs(positions) do
+		local name = minetest.get_node(connected_pos).name
+		if machines[name] or technic.get_cable_tier(name) then
+			table.insert(connections,connected_pos)
+		end
+	end
+	return connections
+end
+
+local function clear_networks(pos)
+	local node = minetest.get_node(pos)
+	local meta = minetest.get_meta(pos)
+	local placed = node.name ~= "air"
+	local positions = check_connections(pos)
+	if #positions < 1 then return end
+	local dead_end = #positions == 1
 	for _,connected_pos in pairs(positions) do
 		local net = technic.cables[minetest.hash_node_position(connected_pos)]
 		if net and technic.networks[net] then
+			if dead_end and placed then
+				-- Dead end placed, add it to the network
+				-- Get the network
+				local network_id = technic.cables[minetest.hash_node_position(positions[1])]
+				if not network_id then
+					-- We're evidently not on a network, nothing to add ourselves to
+					return
+				end
+				local sw_pos = minetest.get_position_from_hash(network_id)
+				sw_pos.y = sw_pos.y + 1
+				local network = technic.networks[network_id]
+				local tier = network.tier
+
+				-- Actually add it to the (cached) network
+				-- This is similar to check_node_subp
+				technic.cables[minetest.hash_node_position(pos)] = network_id
+				pos.visited = 1
+				if technic.is_tier_cable(name, tier) then
+					table.insert(network.all_nodes,pos)
+				elseif technic.machines[tier][node.name] then
+					meta:set_string(tier.."_network",minetest.pos_to_string(sw_pos))
+					if     technic.machines[tier][node.name] == technic.producer then
+						table.insert(network.PR_nodes,pos)
+					elseif technic.machines[tier][node.name] == technic.receiver then
+						table.insert(network.RE_nodes,pos)
+					elseif technic.machines[tier][node.name] == technic.producer_receiver then
+						table.insert(network.PR_nodes,pos)
+						table.insert(network.RE_nodes,pos)
+					elseif technic.machines[tier][node.name] == "SPECIAL" and
+							(pos.x ~= sw_pos.x or pos.y ~= sw_pos.y or pos.z ~= sw_pos.z) and
+							from_below then
+						table.insert(network.SP_nodes,pos)
+					elseif technic.machines[tier][node.name] == technic.battery then
+						table.insert(network.BA_nodes,pos)
+					end
+				end
+			elseif dead_end and not placed then
+				-- Dead end removed, remove it from the network
+				-- Get the network
+				local network_id = technic.cables[minetest.hash_node_position(positions[1])]
+				if not network_id then
+					-- We're evidently not on a network, nothing to add ourselves to
+					return
+				end
+				local network = technic.networks[network_id]
+
+				-- Search for and remove machine
+				technic.cables[minetest.hash_node_position(pos)] = nil
+				for tblname,table in pairs(network) do
+					if tblname ~= "tier" then
+						for machinenum,machine in pairs(table) do
+							if machine.x == pos.x
+							and machine.y == pos.y
+							and machine.z == pos.z then
+								table[machinenum] = nil
+							end
+						end
+					end
+				end
+			else
+				-- Not a dead end, so the whole network needs to be recalculated
 				for _,v in pairs(technic.networks[net].all_nodes) do
 					local pos1 = minetest.hash_node_position(v)
 					technic.cables[pos1] = nil
@@ -30,6 +115,7 @@ local function clear_networks(pos)
 			end
 		end
 	end
+end
 
 function technic.register_cable(tier, size)
 	local ltier = string.lower(tier)