+ -- We make a stack, and manually maintain size for performance.
+ -- Stored in the stack, we will maintain tables with pos, and
+ -- last neighbor visited. This way, when we get back to each
+ -- node, we know which directions we have already walked, and
+ -- which direction is the next to walk.
+ local s = {}
+ local n = 0
+ -- The neighbor order we will visit from our table.
+ local v = 1
+
+ while true do
+ -- Push current pos onto the stack.
+ n = n + 1
+ s[n] = {p = p, v = v}
+ -- Select next node from neighbor list.
+ p = vector.add(p, check_for_falling_neighbors[v])
+ -- Now we check out the node. If it is in need of an update,
+ -- it will let us know in the return value (true = updated).
+ if not core.check_single_for_falling(p) then
+ -- If we don't need to "recurse" (walk) to it then pop
+ -- our previous pos off the stack and continue from there,
+ -- with the v value we were at when we last were at that
+ -- node
+ repeat
+ local pop = s[n]
+ p = pop.p
+ v = pop.v
+ s[n] = nil
+ n = n - 1
+ -- If there's nothing left on the stack, and no
+ -- more sides to walk to, we're done and can exit
+ if n == 0 and v == 11 then
+ return
+ end
+ until v < 11
+ -- The next round walk the next neighbor in list.
+ v = v + 1
+ else
+ -- If we did need to walk the neighbor, then
+ -- start walking it from the walk order start (1),
+ -- and not the order we just pushed up the stack.
+ v = 1
+ end