darkrc/bin/factors

#!/usr/bin/env luajit

local primes = require 'primes'

local arrr = require 'arrr'

local parser = arrr {
	{ "Enable batch factorization", "--batch", "-b" };
	{ "Initialize prime table up to the Nth prime", "--initialize", "-n", "n", tonumber };
  { "Cache file", "--cache", "-c", 1, io.open };
}

local options = parser {...}

if options.cache then
  local i = 1
  for line in options.cache:lines() do
    primes[i] = tonumber(line)
    i = i + 1
  end
end

if options.initialize then
	for i=1, options.initialize do
		local _ = primes[i]
	end
end

if not options.batch then
	local number = options[1] and tonumber(options[1])
	if not number then
		io.write("Please input a number: ")
		number = assert(tonumber(io.read())) -- Try 351681238432 ;)
	end

	for i, factor in ipairs{primes:factorize(number)} do
		print(factor)
	end
else
	for number in io.lines() do
		number = assert(tonumber(number))
		print(number.." = "..table.concat({primes:factorize(number)}, " + "))
	end
end