gol-ls.ls

/**
 * Conway's Game of Life, in LiveScript
 * ====================================
 * 
 * Conway's Game of Life is a cellular automaton, published by John H Conway
 * in 1970, fulfilling the design principles but greatly simplifying the
 * research of von Neumann, into a hypothetical machine that could build
 * copies of itself. It is a zero-player game, meaning there is no input, and
 * the game will progress on its own with a 'seed', or configuration, to
 * begin with.
 *
 * As a computer simulation, Life (as it will be herein abbreviated) has had
 * phenomenal cultural interest across all different fields; in my usage here,
 * I am implementing a familiar objective pattern for Life in different
 * languages, and in as idiomatic a structure and style as I can, in that
 * language.
 */

class CellState
  (@_state) ->

  @LIVE = new this true
  @DEAD = new this false

class Cell
  -> @_state = CellState.DEAD

  get-state: -> @_state
  set-state: (@_state) ->

class FlatVector
  (@x, @y) ->

  plus: (v) -> new FlatVector @x + v.x, @y + v.y
  to-id: (w) ->
    | y < 1     => x
    | otherwise => w * (y - 1) + x

  from-id = (i, w, h) -> 
    | i > (w - 1) * (h - 1) => false
    | otherwise             => new FlatVector (i % iw), (floor i / iw) + 1

class World
  (@width, @height) ->
    @_cells = []
    @each (v) ->
      @_cells[v.to-id!] = new Cell

  each: -> (callback, endline-callback) ~>
    for y til @width
      for x til @height
        callback new Vector x, y
      endline-callback?!

  get-cell-state: (v) ~> @_cells[v.to-id!]get-state!
  set-cell-state: (v, s) ~> @_cells[v.to-id!]set-state s

  get-neighbors: (v) ~>
    # Each of these coordinates corresponds with a relative direction in two
    # dimensions, in the order:
    #   NW, N, NE, W, E, SW, S, SE
    n = []
    each [[-1 -1] [0 -1] [1 -1] [-1 0] [1 0], [-1 1] [0 1] [1 1]] ([x, y]) ->
      n.push v.plus new FlatVector x, y
    return n

  get-num-living-neighbors: (v) ~>
    length filter (n) ->
      @_cells.get-cell-state n.to-id! is CellState.LIVE, @get-neighbors

class GameOfLife
  (@world) ->

  tick: ->
    nw = new World @world.width!, @world.height!
    @world.each (v) ->
      c = v.get-num-living-neighbors!
      state = switch c
      | 3 => CellState.LIVE
      | 2 => @world.get-cell-state v
      | _ => CellState.DEAD
      nw.set-cell-state v, state
    @world = nw