Run permutations of a program

permutator

#!/usr/bin/ruby

require 'pty'

def generate_permutations cmd_template, lists, vars=[]
	if lists.empty?
		cmd = String.new(cmd_template)
		vars.each_with_index { |var, i| cmd.gsub! "{#{i}}", var }
		if $preview
			puts cmd
		else
			PTY.spawn(cmd) do |output, input|
				begin
					output.each { |line| puts line }
				rescue Errno::EIO
					# do nothing
				end
			end
		end
	else
		lists[0].each do |elem|
			vars.push(elem)
			generate_permutations cmd_template, lists[1..-1], vars
			vars.pop
		end
	end
end

def generate_permutation_lists params
	lists = Array.new
	file_index = params.index "-f"
	
	while file_index
		if file_index == params.length - 1
			params.delete "-f"
			break
		elsif params[file_index + 1] == "-f"
			params.delete_at file_index
		else
			begin
				filepath = params[file_index + 1]
				from_file = File.read(filepath).split("\n")
				lists.push(from_file)
				2.times { params.delete_at file_index }

				file_index = params.index "-f"
			rescue StandardError => err
				puts "Unable to read from file: #{filepath} (#{err})"
				return
			end
		end
	end

	return lists
end

def main params
	$preview = false
	if params.include? "--preview" or params.include? "-p"
		$preview = true
		params.delete "--preview"
		params.delete "-p"
	end

	lists = generate_permutation_lists params
	cmd = params.join(" ")
	generate_permutations cmd, lists
end

main ARGV