(Lua) Print Table function

--[[
Most pure lua print table functions I've seen have a problem with deep recursion and tend to cause a stack overflow when going too deep. This print table function that I've written does not have this problem. It should also be capable of handling really large tables due to the way it handles concatenation. In my personal usage of this function, it outputted 63k lines to file in about a second.

The output also keeps lua syntax and the script can easily be modified for simple persistent storage by writing the output to file if modified to allow only number, boolean, string and table data types to be formatted.

author: Alundaio (aka Revolucas)
--]]

function print_table(node)
    -- to make output beautiful
    local function tab(amt)
        local str = ""
        for i=1,amt do
            str = str .. "\t"
        end
        return str
    end

    local cache, stack, output = {},{},{}
    local depth = 1
    local output_str = "{\n"

    while true do
        local size = 0
        for k,v in pairs(node) do
            size = size + 1
        end

        local cur_index = 1
        for k,v in pairs(node) do
            if (cache[node] == nil) or (cur_index >= cache[node]) then

                if (string.find(output_str,"}",output_str:len())) then
                    output_str = output_str .. ",\n"
                elseif not (string.find(output_str,"\n",output_str:len())) then
                    output_str = output_str .. "\n"
                end

                -- This is necessary for working with HUGE tables otherwise we run out of memory using concat on huge strings
                table.insert(output,output_str)
                output_str = ""

                local key
                if (type(k) == "number" or type(k) == "boolean") then
                    key = "["..tostring(k).."]"
                else
                    key = "['"..tostring(k).."']"
                end

                if (type(v) == "number" or type(v) == "boolean") then
                    output_str = output_str .. tab(depth) .. key .. " = "..tostring(v)
                elseif (type(v) == "table") then
                    output_str = output_str .. tab(depth) .. key .. " = {\n"
                    table.insert(stack,node)
                    table.insert(stack,v)
                    cache[node] = cur_index+1
                    break
                else
                    output_str = output_str .. tab(depth) .. key .. " = '"..tostring(v).."'"
                end

                if (cur_index == size) then
                    output_str = output_str .. "\n" .. tab(depth-1) .. "}"
                else
                    output_str = output_str .. ","
                end
            else
                -- close the table
                if (cur_index == size) then
                    output_str = output_str .. "\n" .. tab(depth-1) .. "}"
                end
            end

            cur_index = cur_index + 1
        end

        if (#stack > 0) then
            node = stack[#stack]
            stack[#stack] = nil
            depth = cache[node] == nil and depth + 1 or depth - 1
        else
            break
        end
    end

    -- This is necessary for working with HUGE tables otherwise we run out of memory using concat on huge strings
    table.insert(output,output_str)
    output_str = table.concat(output)

    print(output_str)
end