perm.rb: explodes ARGV as a TSV (permutate 'foo bar baz' 'quu qux' yields 6 lines)

perm.rb

# frozen_string_literal: true
# permutate.rb: MIT license. @snipsnipsnip
require 'csv'
require 'optparse'
require 'shellwords'

def main(argv=ARGV)
  filter = nil
  rest = nil
  need_header = false
  unique_marker = nil
  utate = false

  OptionParser.new do |o|
    o.banner += " ['a b c' 'd e %1$s'...]"
    o.separator "Options:"
    o.on('-c', '--column-header', "Treat first value ('a' and 'd' in the usage) as a title row", TrueClass) {|a| need_header = a }
    o.on('-u [OMITTED-MARKER]', '--only-unique-value', "Replaces duplicate output with OMITTED-MARKER", String) {|a| unique_marker = a || "" }
    o.on('--utate', "Permutates columns", TrueClass) {|a| utate = true }
    o.on('-e CODE', '--eval', "Applies filter. CODE must return a callable (String[] -> String[] | nil)", String) {|a| filter = TOPLEVEL_BINDING.eval(a) }
    o.on('-h', '--help') { abort o.to_s }
    rest = o.parse(argv)

    abort o.to_s if rest.empty?
    abort "CODE must return a callable (String[] -> String[] | nil)" unless !filter || filter.respond_to?(:call)
    true
  end or return

  CSV(col_sep: "\t") do |csv|
    orig_cols = rest.map {|x| Shellwords.shellsplit x.strip }

    permutated_cols = utate ? orig_cols.permutation : [orig_cols]
    no = 1
    prev_line = nil
    permutated_cols.each do |cols|
      if need_header
        csv << ['No', *cols.map(&:first)]
        cols = cols.map {|c| c.drop 1 }
      end

      :product.to_proc.(*cols) do |line|
        line.map! {|c| c.include?(?%) ? c % line : c }
        line = filter.call(line) || next if filter

        curr_line = [no, *line]

        if prev_line && unique_marker
          line.each_index do |col|
            curr_line[col + 1] = unique_marker if line[col] == prev_line[col]
          end
        end

        csv << curr_line

        no += 1
        prev_line = line
      end
    end
  end
end

main if $0 == __FILE__