Numerical Character References

ncr.rb

#!/usr/bin/env ruby
# -*- coding: utf-8 -*-

# Numerical Character References

if RUBY_VERSION < "1.9"
  $KCODE = "u"

  class String
    def ord
      self[0]
    end
  end
end

require "optparse"

module Ncr
  module_function

  def get_ref(param, opt = {})
    code = 0
    ch = ""

    case param
    when /^[1-9]/
      ch = $&
      num = ch.to_i
      code = 9311 + num
    when /^0/
      ch = $&
      code = 0x24ea
    when /^heart/i
      ch = $&
      code = 0x2665
    when /^jis/i
      ch = $&
      code = 0x3004
    when /^[a-z]/
      ch = $&
      code = 0x24d0 + (ch.ord - ?a.ord)
    end

    opt[:ch] = ch
    code_to_s(code, opt)
  end

  def code_to_s(code, opt = {})
    str = (opt[:hex] ? "&\#x%x;" : "&\#%d;") % code
    if opt[:output] != :short
      str += " ... #{opt[:ch]}"
    end
    if opt[:output] == :html
      str += "<br>"
    end
    str
  end
end

if __FILE__ == $0
  op = OptionParser.new
  h = {}
  op.on("-x", "--hexadecimal", "hexadecimal") {
    h[:hex] = true
  }
  op.on("-s", "--short", "values only") {
    h[:output] = :short
  }
  op.on("-h", "--html", "HTML") {
    h[:output] = :html
  }
  op.parse!(ARGV)

  if ARGV.empty?
    argv = ["1"]
  else
    argv = ARGV
  end
  argv.each do |param|
    puts Ncr.get_ref(param, h)
  end
end

# Example
#   ruby ncr.rb
#   ruby ncr.rb -x 1
#   ruby ncr.rb -s 1
#   ruby ncr.rb -xh 1 2 3 4 5 heart jis a b c x y z