256 terminal colors and hex colors in Ruby

colors256.rb

class Array
  def generate_color(num, reg)
    each.with_index(num) do |hexcolor, termcolor|
      number = "#{termcolor}".ljust(3)
      bg = "\e[48;5;#{termcolor}m  \e[0m"
      fg = "\e[38;5;#{termcolor}m #{number} ##{hexcolor} \e[0m"
      print bg + fg
      print "\n" if reg =~ hexcolor
    end
  end
end

def system_color
  hex = %w(000000 800000 008000 808000 000080 800080 008080 c0c0c0 808080 ff0000 00ff00 ffff00 0000ff ff00ff 00ffff ffffff)

  hex.generate_color(0, /(c0|ffffff)$/)
end

def color_cube
  hex = []
  el = %w(00 5f 87 af d7 ff)
  el.each do |r|
    el.each do |g|
      el.each do |b|
        hex << r + g + b
      end
    end
  end

  hex.generate_color(16, /f{2}$/)
end

def gray_scale
  el = %w(08 12 1c 26 30 3a 44 4e 58 60 66 76 80 8a 94 9e a8 b2 bc c6 d0 da e4 ee)
  hex = el.map { |i| i * 3 }

  hex.generate_color(232, /(4e|9e|ee)$/)
end

system_color
color_cube
gray_scale