lisp/play/life.el

   1 ;;; life.el --- John Horton Conway's `Life' game for GNU Emacs
   2
   3 ;; Copyright (C) 1988 Free Software Foundation, Inc.
   4 ;; Contributed by Kyle Jones, talos!kjones@uunet.uu.net
   5
   6 ;; This file is part of GNU Emacs.
   7
   8 ;; GNU Emacs is free software; you can redistribute it and/or modify
   9 ;; it under the terms of the GNU General Public License as published by
  10 ;; the Free Software Foundation; either version 1, or (at your option)
  11 ;; any later version.
  12
  13 ;; GNU Emacs is distributed in the hope that it will be useful,
  14 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 ;; GNU General Public License for more details.
  17
  18 ;; You should have received a copy of the GNU General Public License
  19 ;; along with GNU Emacs; see the file COPYING.  If not, write to
  20 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  21
  22 (defconst life-patterns
  23   [("@@@" " @@" "@@@")
  24    ("@@@ @@@" "@@  @@ " "@@@ @@@")
  25    ("@@@ @@@" "@@   @@" "@@@ @@@")
  26    ("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@")
  27    ("@@@@@@@@@@")
  28    ("   @@@@@@@@@@       "
  29     "     @@@@@@@@@@     "
  30     "       @@@@@@@@@@   "
  31     "@@@@@@@@@@          "
  32     "@@@@@@@@@@          ")
  33    ("@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@")
  34    ("@               @" "@               @"  "@               @"
  35     "@               @" "@               @"  "@               @"
  36     "@               @" "@               @"  "@               @"
  37     "@               @" "@               @"  "@               @"
  38     "@               @" "@               @"  "@               @")
  39    ("@@               " " @@              " "  @@             "
  40     "   @@            " "    @@           " "     @@          "
  41     "      @@         " "       @@        " "        @@       "
  42     "         @@      " "          @@     " "           @@    "
  43     "            @@   " "             @@  " "              @@ "
  44     "               @@")
  45    ("@@@@@@@@@" "@   @   @" "@ @@@@@ @" "@ @   @ @" "@@@   @@@"
  46     "@ @   @ @" "@ @@@@@ @" "@   @   @" "@@@@@@@@@")]
  47   "Vector of rectangles containing some Life startup patterns.")
  48
  49 ;; Macros are used macros for manifest constants instead of variables
  50 ;; because the compiler will convert them to constants, which should
  51 ;; eval faster than symbols.
  52 ;;
  53 ;; The (require) wrapping forces the compiler to eval these macros at
  54 ;; compile time.  This would not be necessary if we did not use macros
  55 ;; inside of macros, which the compiler doesn't seem to check for.
  56 ;;
  57 ;; Don't change any of the life-* macro constants unless you thoroughly
  58 ;; understand the `life-grim-reaper' function.
  59 (require
  60  (progn
  61    (defmacro life-life-char () ?@)
  62    (defmacro life-death-char () (1+ (life-life-char)))
  63    (defmacro life-birth-char () 3)
  64    (defmacro life-void-char () ?\ )
  65
  66    (defmacro life-life-string () (char-to-string (life-life-char)))
  67    (defmacro life-death-string () (char-to-string (life-death-char)))
  68    (defmacro life-birth-string () (char-to-string (life-birth-char)))
  69    (defmacro life-void-string () (char-to-string (life-void-char)))
  70    (defmacro life-not-void-regexp () (concat "[^" (life-void-string) "\n]"))
  71
  72    ;; try to optimize the (goto-char (point-min)) & (goto-char (point-max))
  73    ;; idioms.  This depends on goto-char's not griping if we underrshoot
  74    ;; or overshoot beginning or end of buffer.
  75    (defmacro goto-beginning-of-buffer () '(goto-char 1))
  76    (defmacro maxint () (lsh (lsh (lognot 0) 1) -1))
  77    (defmacro goto-end-of-buffer () '(goto-char (maxint)))
  78
  79    (defmacro increment (variable) (list 'setq variable (list '1+ variable)))
  80    'life))
  81
  82 ;; list of numbers that tell how many characters to move to get to
  83 ;; each of a cell's eight neighbors.
  84 (defconst life-neighbor-deltas nil)
  85
  86 ;; window display always starts here.  Easier to deal with than
  87 ;; (scroll-up) and (scroll-down) when trying to center the display.
  88 (defconst life-window-start nil)
  89
  90 ;; For mode line
  91 (defconst life-current-generation nil)
  92 ;; Sadly, mode-line-format won't display numbers.
  93 (defconst life-generation-string nil)
  94
  95 (defun abs (n) (if (< n 0) (- n) n))
  96
  97 (defun life (&optional sleeptime)
  98   "Run Conway's Life simulation.
  99 The starting pattern is randomly selected.  Prefix arg (optional first
 100 arg non-nil from a program) is the number of seconds to sleep between
 101 generations (this defaults to 1)."
 102   (interactive "p")
 103   (or sleeptime (setq sleeptime 1))
 104   (life-setup)
 105   (life-display-generation sleeptime)
 106   (while t
 107     (let ((inhibit-quit t))
 108       (life-grim-reaper)
 109       (life-expand-plane-if-needed)
 110       (life-increment-generation)
 111       (life-display-generation sleeptime))))
 112
 113 (fset 'life-mode 'life)
 114 (put 'life-mode 'mode-class 'special)
 115
 116 (random t)
 117
 118 (defun life-setup ()
 119   (let (n)
 120     (switch-to-buffer (get-buffer-create "*Life*") t)
 121     (erase-buffer)
 122     (kill-all-local-variables)
 123     (setq case-fold-search nil
 124           mode-name "Life"
 125           major-mode 'life-mode
 126           truncate-lines t
 127           life-current-generation 0
 128           life-generation-string "0"
 129           mode-line-buffer-identification '("Life: generation "
 130                                             life-generation-string)
 131           fill-column (1- (window-width))
 132           life-window-start 1)
 133     (buffer-disable-undo (current-buffer))
 134     ;; stuff in the random pattern
 135     (life-insert-random-pattern)
 136     ;; make sure (life-life-char) is used throughout
 137     (goto-beginning-of-buffer)
 138     (while (re-search-forward (life-not-void-regexp) nil t)
 139       (replace-match (life-life-string) t t))
 140     ;; center the pattern horizontally
 141     (goto-beginning-of-buffer)
 142     (setq n (/ (- fill-column (save-excursion (end-of-line) (point))) 2))
 143     (while (not (eobp))
 144       (indent-to n)
 145       (forward-line))
 146     ;; center the pattern vertically
 147     (setq n (/ (- (1- (window-height))
 148                   (count-lines (point-min) (point-max)))
 149                2))
 150     (goto-beginning-of-buffer)
 151     (newline n)
 152     (goto-end-of-buffer)
 153     (newline n)
 154     ;; pad lines out to fill-column
 155     (goto-beginning-of-buffer)
 156     (while (not (eobp))
 157       (end-of-line)
 158       (indent-to fill-column)
 159       (move-to-column fill-column)
 160       (delete-region (point) (progn (end-of-line) (point)))
 161       (forward-line))
 162     ;; expand tabs to spaces
 163     (untabify (point-min) (point-max))
 164     ;; before starting be sure the automaton has room to grow
 165     (life-expand-plane-if-needed)
 166     ;; compute initial neighbor deltas
 167     (life-compute-neighbor-deltas)))
 168
 169 (defun life-compute-neighbor-deltas ()
 170   (setq life-neighbor-deltas
 171         (list -1 (- fill-column)
 172               (- (1+ fill-column)) (- (+ 2 fill-column))
 173               1 fill-column (1+ fill-column)
 174               (+ 2 fill-column))))
 175
 176 (defun life-insert-random-pattern ()
 177   (insert-rectangle
 178    (elt life-patterns (% (abs (random)) (length life-patterns))))
 179   (insert ?\n))
 180
 181 (defun life-increment-generation ()
 182   (increment life-current-generation)
 183   (setq life-generation-string (int-to-string life-current-generation)))
 184
 185 (defun life-grim-reaper ()
 186   ;; Clear the match information.  Later we check to see if it
 187   ;; is still clear, if so then all the cells have died.
 188   (store-match-data nil)
 189   (goto-beginning-of-buffer)
 190   ;; For speed declare all local variable outside the loop.
 191   (let (point char pivot living-neighbors list)
 192     (while (search-forward (life-life-string) nil t)
 193       (setq list life-neighbor-deltas
 194             living-neighbors 0
 195             pivot (1- (point)))
 196       (while list
 197         (setq point (+ pivot (car list))
 198               char (char-after point))
 199         (cond ((eq char (life-void-char))
 200                (subst-char-in-region point (1+ point)
 201                                      (life-void-char) 1 t))
 202               ((< char 3)
 203                (subst-char-in-region point (1+ point) char (1+ char) t))
 204               ((< char 9)
 205                (subst-char-in-region point (1+ point) char 9 t))
 206               ((>= char (life-life-char))
 207                (increment living-neighbors)))
 208         (setq list (cdr list)))
 209       (if (memq living-neighbors '(2 3))
 210           ()
 211         (subst-char-in-region pivot (1+ pivot)
 212                             (life-life-char) (life-death-char) t))))
 213   (if (null (match-beginning 0))
 214       (life-extinct-quit))
 215   (subst-char-in-region 1 (point-max) 9 (life-void-char) t)
 216   (subst-char-in-region 1 (point-max) 1 (life-void-char) t)
 217   (subst-char-in-region 1 (point-max) 2 (life-void-char) t)
 218   (subst-char-in-region 1 (point-max) (life-birth-char) (life-life-char) t)
 219   (subst-char-in-region 1 (point-max) (life-death-char) (life-void-char) t))
 220
 221 (defun life-expand-plane-if-needed ()
 222   (catch 'done
 223     (goto-beginning-of-buffer)
 224     (while (not (eobp))
 225       ;; check for life at beginning or end of line.  If found at
 226       ;; either end, expand at both ends,
 227       (cond ((or (eq (following-char) (life-life-char))
 228                  (eq (progn (end-of-line) (preceding-char)) (life-life-char)))
 229              (goto-beginning-of-buffer)
 230              (while (not (eobp))
 231                (insert (life-void-char))
 232                (end-of-line)
 233                (insert (life-void-char))
 234                (forward-char))
 235            (setq fill-column (+ 2 fill-column))
 236            (scroll-left 1)
 237            (life-compute-neighbor-deltas)
 238            (throw 'done t)))
 239       (forward-line)))
 240   (goto-beginning-of-buffer)
 241   ;; check for life within the first two lines of the buffer.
 242   ;; If present insert two lifeless lines at the beginning..
 243   (cond ((search-forward (life-life-string)
 244                          (+ (point) fill-column fill-column 2) t)
 245          (goto-beginning-of-buffer)
 246          (insert-char (life-void-char) fill-column)
 247          (insert ?\n)
 248          (insert-char (life-void-char) fill-column)
 249          (insert ?\n)
 250          (setq life-window-start (+ life-window-start fill-column 1))))
 251   (goto-end-of-buffer)
 252   ;; check for life within the last two lines of the buffer.
 253   ;; If present insert two lifeless lines at the end.
 254   (cond ((search-backward (life-life-string)
 255                           (- (point) fill-column fill-column 2) t)
 256          (goto-end-of-buffer)
 257          (insert-char (life-void-char) fill-column)
 258          (insert ?\n)
 259          (insert-char (life-void-char) fill-column)
 260          (insert ?\n)
 261          (setq life-window-start (+ life-window-start fill-column 1)))))
 262
 263 (defun life-display-generation (sleeptime)
 264   (goto-char life-window-start)
 265   (recenter 0)
 266   (sit-for sleeptime))
 267
 268 (defun life-extinct-quit ()
 269   (life-display-generation 0)
 270   (signal 'life-extinct nil))
 271
 272 (put 'life-extinct 'error-conditions '(life-extinct quit))
 273 (put 'life-extinct 'error-message "All life has perished")
 274
 275 (provide 'life)
 276
 277 ;;; life.el ends here