How would you go about checking if a table is cyclic or contains a cyclic table

[GetStyled]

I’m having trouble thinking of a way to do this without turning it into spaghetti code. Is there a simple way to accomplish this?

also an example of a cyclic table is:

local a = {}
local b = {}
a[1] = b
b[1] = a

[waves5217 (waves)]

There are no built-in ways to detect cyclic tables, but I threw together a quick recursive function that seems to work. It’s as easy as I could get it. Recursively checks all tables and those marked as tracked have already been visited. You’ll have to take some consumed memory into account. Please let me know if you find any mistakes or the output isn’t correct.

To improve efficiency, going by layers might improve execution time. Depends on extents of the table and the number of nested tables. I used Depth-first search - Wikipedia.

If your tables are small, the difference is almost negligible. Otherwise, different algorithms suit different tables. The polar opposite of Depth-first search is Breadth-first search - Wikipedia.

local function ContainsCyclicReference(tbl)
	local tracked = {} -- all visited tables
	
	local function DeepSearch(t)
		tracked[t] = true
		
		for _,v in t do
			if typeof(v) ~= "table" then continue; end
			return tracked[v] and true or DeepSearch(v)
		end
		return false
	end
	return DeepSearch(tbl)
end

local a = {}
local b = {}
local c = {}
a[1] = b
b[1] = {[1] = {[2] = c}}
c[1] = a

print(ContainsCyclicReference(a)) --> true