markov.rb

class Markov
  attr_reader :order, :phrases
  
  def initialize(corpus=[], order=3)
    @order = order
    @phrases = Hash.new {|h,k| h[k] = []}
    add(corpus)
  end
  
  def add(corpus)
    corpus = read_if_file(corpus)
    corpus.each_with_index do |word, index|
      phrase = corpus[index, order]
      phrases[phrase] << corpus[index + order]
    end
  end
  
  def generate(max=100)
    seed = @phrases.keys.sample
    output = []
    
    max.times do
      options = phrases[seed]
      output << seed.shift
      seed.push(options[rand(options.length)])
      break if seed.compact.empty?
    end
    output.join(" ")
  end
  
  private
  def read_if_file(object)
    object = File.open(File.expand_path(object)) if object.respond_to?(:to_str)
    if object.respond_to?(:each_line)
      array = []
      object.each_line {|line| array.push(*line.scan(/\S+/))}
      object.close if object.respond_to?(:close)
      object = array
    end
    object
  end
end