Ruby でライフゲーム

• 50行で作る、HTML5+JavaScriptな簡単ライフゲーム

これを見て作りたくなったからつくった。
あれれ、130行になったぞ……　まあ、使っていないコードもあるのと、割と丁寧に書いてはいる気がするのでこんなもんで……

life.rb

require 'singleton'

FPS = 30.0 # 60.0
SIZE = 75

def mainloop
  loop do
    update
    sleep 1.000 / FPS
  end
end

def clear
  puts "\e[H\e[2J"
end

def update
  field = Field.instance
  field.each do |cell|
    count = cell.around_self.map{|x, y| field.get(x, y) }.count(&:alive?)
    new_cell = case
               when (2..3).cover?(count) && cell.alive?
                 cell.to_alive
               when count == 3           && cell.dead?
                 cell.to_alive
               else
                 cell.to_dead
               end
    field.set(new_cell)
  end
  field.commit
  clear
  puts field.to_s
end

class Field
  include Enumerable
  include Singleton

  def initialize
    @field = 
      get_mock_field.map.with_index do |row, y|
        row.map.with_index{|_, x| Cell.gen(x, y) }
      end
    clear_tmp_field
  end
  attr_reader :field, :tmp_field

  def to_s
    each_row.map do |row|
      row.map(&:to_s).join(" ")
    end.join("\n")
  end

  def get(x, y)
    return nil if x < 0 or x > SIZE or y < 0 or y > SIZE
    field[y][x]
  end

  def set(cell)
    tmp_field[cell.y][cell.x] = cell
  end

  def commit
    @field = tmp_field
    clear_tmp_field
  end

  def each
    return to_enum unless block_given?
    @field.flatten.each do |cell|
      yield cell
    end
  end

  def each_row
    return enum_for(:each_row) unless block_given?
    @field.each do |row|
      yield row
    end
  end

  private
  def clear_tmp_field
    @tmp_field = get_mock_field
  end

  def get_mock_field
    ([[nil] * SIZE] * SIZE).map{|r| r.clone } # change pointer
  end
end

class Cell < Struct.new(:cont, :x, :y)
  def self.gen(x, y)
    new [true, false].sample, x, y
  end

  def to_s
    cont ? "@" : "_"
  end

  alias alive? cont
  def dead?; !alive? end

  def to_toggled
    Cell.new(!cont, x, y)
  end

  def to_alive
    Cell.new(true, x, y)
  end

  def to_dead
    Cell.new(false, x, y)
  end

  def around_self
    return enum_for(:around_self) unless block_given?
    x_min = [0       , x - 1].max
    x_max = [SIZE - 1, x + 1].min
    y_min = [0       , y - 1].max
    y_max = [SIZE - 1, y + 1].min
    [*x_min..x_max].product([*y_min..y_max]).each do |_x, _y|
      next if x == _x and y == _y
      yield _x, _y
    end
  end
end

mainloop