Anagrams in Ruby

anagram.rb

#!/usr/bin/env ruby -wKU

require 'optparse'

dictionary = '/usr/share/dict/words'

OptionParser.new do |opts|
  opts.banner = 'Usage: anagram [ options ] word...'

  opts.on('-d', '--dict path', String, 'Path to dictionary') do |dict|
    dictionary = dict
  end

  opts.on('-h', '--help', 'Show this message') do
    puts opts
    exit
  end

  begin
    ARGV << '-h' if ARGV.empty?
    opts.parse!(ARGV)
  rescue OptionParser::ParseError => e
    STDERR.puts e.message, '\n', opts
    exit(-1)
  end
end

# convert "wombat" into "abmotw". All anagrams share a signature
def signature_of(word)
  word.unpack("c*").sort.pack("c*")
end

signatures = Hash.new

File.foreach(dictionary) do |line|
  word = line.chomp
  signature = signature_of(word) 
  (signatures[signature] ||= []) << word
end

ARGV.each do |word|
  signature = signature_of(word)
  if signatures[signature]
    puts "Anagrams of #{word}: #{signatures[signature].join(', ')}"
  else
    puts "No anagrams of #{word} in #{dictionary}"
  end
end