How to iterate all content in a table using loops?

Please note:

I know how to iterate a table, this question is basically asking how to iterate ALL content in a table. For example, if you have a table like: local t = {a = 1, b = {1,2,3}} , I'd want to return a table with all it's unpacked data, assuming there are nested tables in it. Like getting all descendants of an object, except instead of iterating an object, it'd be a table.

Question

I know how I could iterate all content in a table with recursive functions, but is there a way to do it with loops instead? This is my current code for my current table iteration:

local function tree(t)
	local all = {}
	local function add(x)
		for i,v in next, x do
			all[#all+1] = v
			if type(v) == "table" then
				add(v)
			end
		end
	end
	add(t)
	return all
end

for i,v in next, tree{
	a = 1,
	b = {1,2,3}
} do print(i,v) end -- prints all values

But I'd like a looped alternative a lot more. If anyone knows how or if this is possible, I'd appreciate the explanation. Thanks.

To iterate through nested tables, you can used nested loops inside of nested functions.

local test = {1,2,3,a = {4,5,b = {6}}}

local function printall(tab)
	for i,v in pairs(tab) do
	if type(v) == "table" then --if v is a table then
	printall(v) --run the function again on the value v
	else
	print(v)
	end
	end
end

printall(test)

additionally, you could use coroutines so that iterating through the nested tables wouldn't effect the rest of the code.

local test = {1,2,3,a = {4,5,b = {6}}}

local function printall(tab)
	for i,v in pairs(tab) do
	if type(v) == "table" then --if v is a table then
	coroutine.resume(coroutine.create(printall),v) --run the function again on the value v under a new thread
	else
	print(v)
	end
	end
end

coroutine.resume(coroutine.create(printall),test)

EDITED

You could use a while loop:

local tab = {}
local num = 0

while num < #tab do
	num = num + 1
	if type(tab[num]) == "table" then
		for _,v in pairs (tab[num]) do
			print(v)
		end
	else
		print(tab[num])
	end
end

or a repeat loop:

local tab = {}
local num = 0

repeat
num = num + 1
if type(tab[num]) == "table" then
	for _,v in pairs (tab[num]) do
		print(v)
	end
else
	print(tab[num])
end
until
num == #tab

Both basically continue until num is equal to #tab.

type() is a function used to get the type of value you are putting into it's parameters.