Translator of unicode regex ranges

unicode_translator.rb

#!/usr/bin/env ruby

# Prints what regex unicode ranges passed via STDIN actually mean
#
# Example input:
#
#     [\u0021-\u0027\u002A-\u002E\u003F\u0041-\u005A\u005C\u005F-\u007A\u00AA\u00B5\u00BA\u00C0-\u00D6\u00D8-\u00F6]
#
# Output:
#
#     0021 - 0027: !"#$%&'
#     002A - 002E: *+,-.
#     0041 - 005A: ABCDEFGHIJKLMNOPQRSTUVWXYZ
#     005F - 007A: _`abcdefghijklmnopqrstuvwxyz
#     00C0 - 00D6: ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖ
#     00D8 - 00F6: ØÙÚÛÜÝÞßàáâãäåæçèéêëìíîïðñòóôõö
#     003F: ?
#     005C: \
#     00AA: ª
#     00B5: µ
#     00BA: º

def unicode_regexp_to_characters(input)
  output = []
  input
    .gsub(/\\u(\w{4})-\\u(\w{4})/) do
      chars = ($1.hex .. $2.hex).map { |code| [code].pack('U') }.join
      output << "#{$1} - #{$2}: #{chars}"
      ''
    end
    .scan(/\\u(\w{4})/) do
      char = [$1.hex].pack('U')
      output << "#{$1}: #{char}"
    end
  output
end

STDIN.each_line do |line|
  puts unicode_regexp_to_characters(line).join("\n")
end