blah

#!/usr/bin/env ruby

class Scanner
  KEYWORDS = {
    :direction =>  %w( north south east west etc ),
    :verb => %w( go stop kill eat ),
    :stop => %w( the in of from at it ),
    :noun => %w( door bear princess cabinet )
  }

  Token = Struct.new(:type, :word)

  def self.scan(string)
    string.split.map do |word|
      if key = KEYWORDS.find { |k, v| v.include?(word) }
        Token.new key.shift, word
      end
    end
  end
end

p Scanner.scan 'south' #=> [#<struct Scanner::Token type=:direction, word="south">]
p Scanner.scan 'door'  #=> [#<struct Scanner::Token type=:noun, word="door">]