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
   5 ;; Author: Kyle Jones <talos!kjones@uunet.uu.net>
   6 ;; Keyword: games
   7
   8 ;; This file is part of GNU Emacs.
   9
  10 ;; GNU Emacs is free software; you can redistribute it and/or modify
  11 ;; it under the terms of the GNU General Public License as published by
  12 ;; the Free Software Foundation; either version 2, or (at your option)
  13 ;; any later version.
  14
  15 ;; GNU Emacs is distributed in the hope that it will be useful,
  16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ;; GNU General Public License for more details.
  19
  20 ;; You should have received a copy of the GNU General Public License
  21 ;; along with GNU Emacs; see the file COPYING.  If not, write to
  22 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  23
  24 ;;; Code:
  25
  26 (defconst life-patterns
  27   [("@@@" " @@" "@@@")
  28    ("@@@ @@@" "@@  @@ " "@@@ @@@")
  29    ("@@@ @@@" "@@   @@" "@@@ @@@")
  30    ("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@")
  31    ("@@@@@@@@@@")
  32    ("   @@@@@@@@@@       "
  33     "     @@@@@@@@@@     "
  34     "       @@@@@@@@@@   "
  35     "@@@@@@@@@@          "
  36     "@@@@@@@@@@          ")
  37    ("@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@")
  38    ("@               @" "@               @"  "@               @"
  39     "@               @" "@               @"  "@               @"
  40     "@               @" "@               @"  "@               @"
  41     "@               @" "@               @"  "@               @"
  42     "@               @" "@               @"  "@               @")
  43    ("@@               " " @@              " "  @@             "
  44     "   @@            " "    @@           " "     @@          "
  45     "      @@         " "       @@        " "        @@       "
  46     "         @@      " "          @@     " "           @@    "
  47     "            @@   " "             @@  " "              @@ "
  48     "               @@")
  49    ("@@@@@@@@@" "@   @   @" "@ @@@@@ @" "@ @   @ @" "@@@   @@@"
  50     "@ @   @ @" "@ @@@@@ @" "@   @   @" "@@@@@@@@@")]
  51   "Vector of rectangles containing some Life startup patterns.")
  52
  53 ;; Macros are used macros for manifest constants instead of variables
  54 ;; because the compiler will convert them to constants, which should
  55 ;; eval faster than symbols.
  56 ;;
  57 ;; The (require) wrapping forces the compiler to eval these macros at
  58 ;; compile time.  This would not be necessary if we did not use macros
  59 ;; inside of macros, which the compiler doesn't seem to check for.
  60 ;;
  61 ;; Don't change any of the life-* macro constants unless you thoroughly
  62 ;; understand the `life-grim-reaper' function.
  63 (require
  64  (progn
  65    (defmacro life-life-char () ?@)
  66    (defmacro life-death-char () (1+ (life-life-char)))
  67    (defmacro life-birth-char () 3)
  68    (defmacro life-void-char () ?\ )
  69
  70    (defmacro life-life-string () (char-to-string (life-life-char)))
  71    (defmacro life-death-string () (char-to-string (life-death-char)))
  72    (defmacro life-birth-string () (char-to-string (life-birth-char)))
  73    (defmacro life-void-string () (char-to-string (life-void-char)))
  74    (defmacro life-not-void-regexp () (concat "[^" (life-void-string) "\n]"))
  75
  76    ;; try to optimize the (goto-char (point-min)) & (goto-char (point-max))
  77    ;; idioms.  This depends on goto-char's not griping if we underrshoot
  78    ;; or overshoot beginning or end of buffer.
  79    (defmacro goto-beginning-of-buffer () '(goto-char 1))
  80    (defmacro maxint () (lsh (lsh (lognot 0) 1) -1))
  81    (defmacro goto-end-of-buffer () '(goto-char (maxint)))
  82
  83    (defmacro increment (variable) (list 'setq variable (list '1+ variable)))
  84    'life))
  85
  86 ;; list of numbers that tell how many characters to move to get to
  87 ;; each of a cell's eight neighbors.
  88 (defconst life-neighbor-deltas nil)
  89
  90 ;; window display always starts here.  Easier to deal with than
  91 ;; (scroll-up) and (scroll-down) when trying to center the display.
  92 (defconst life-window-start nil)
  93
  94 ;; For mode line
  95 (defconst life-current-generation nil)
  96 ;; Sadly, mode-line-format won't display numbers.
  97 (defconst life-generation-string nil)
  98
  99 (defun abs (n) (if (< n 0) (- n) n))
 100
 101 (defun life (&optional sleeptime)
 102   "Run Conway's Life simulation.
 103 The starting pattern is randomly selected.  Prefix arg (optional first
 104 arg non-nil from a program) is the number of seconds to sleep between
 105 generations (this defaults to 1)."
 106   (interactive "p")
 107   (or sleeptime (setq sleeptime 1))
 108   (life-setup)
 109   (life-display-generation sleeptime)
 110   (while t
 111     (let ((inhibit-quit t))
 112       (life-grim-reaper)
 113       (life-expand-plane-if-needed)
 114       (life-increment-generation)
 115       (life-display-generation sleeptime))))
 116
 117 (fset 'life-mode 'life)
 118 (put 'life-mode 'mode-class 'special)
 119
 120 (random t)
 121
 122 (defun life-setup ()
 123   (let (n)
 124     (switch-to-buffer (get-buffer-create "*Life*") t)
 125     (erase-buffer)
 126     (kill-all-local-variables)
 127     (setq case-fold-search nil
 128           mode-name "Life"
 129           major-mode 'life-mode
 130           truncate-lines t
 131           life-current-generation 0
 132           life-generation-string "0"
 133           mode-line-buffer-identification '("Life: generation "
 134                                             life-generation-string)
 135           fill-column (1- (window-width))
 136           life-window-start 1)
 137     (buffer-disable-undo (current-buffer))
 138     ;; stuff in the random pattern
 139     (life-insert-random-pattern)
 140     ;; make sure (life-life-char) is used throughout
 141     (goto-beginning-of-buffer)
 142     (while (re-search-forward (life-not-void-regexp) nil t)
 143       (replace-match (life-life-string) t t))
 144     ;; center the pattern horizontally
 145     (goto-beginning-of-buffer)
 146     (setq n (/ (- fill-column (save-excursion (end-of-line) (point))) 2))
 147     (while (not (eobp))
 148       (indent-to n)
 149       (forward-line))
 150     ;; center the pattern vertically
 151     (setq n (/ (- (1- (window-height))
 152                   (count-lines (point-min) (point-max)))
 153                2))
 154     (goto-beginning-of-buffer)
 155     (newline n)
 156     (goto-end-of-buffer)
 157     (newline n)
 158     ;; pad lines out to fill-column
 159     (goto-beginning-of-buffer)
 160     (while (not (eobp))
 161       (end-of-line)
 162       (indent-to fill-column)
 163       (move-to-column fill-column)
 164       (delete-region (point) (progn (end-of-line) (point)))
 165       (forward-line))
 166     ;; expand tabs to spaces
 167     (untabify (point-min) (point-max))
 168     ;; before starting be sure the automaton has room to grow
 169     (life-expand-plane-if-needed)
 170     ;; compute initial neighbor deltas
 171     (life-compute-neighbor-deltas)))
 172
 173 (defun life-compute-neighbor-deltas ()
 174   (setq life-neighbor-deltas
 175         (list -1 (- fill-column)
 176               (- (1+ fill-column)) (- (+ 2 fill-column))
 177               1 fill-column (1+ fill-column)
 178               (+ 2 fill-column))))
 179
 180 (defun life-insert-random-pattern ()
 181   (insert-rectangle
 182    (elt life-patterns (% (abs (random)) (length life-patterns))))
 183   (insert ?\n))
 184
 185 (defun life-increment-generation ()
 186   (increment life-current-generation)
 187   (setq life-generation-string (int-to-string life-current-generation)))
 188
 189 (defun life-grim-reaper ()
 190   ;; Clear the match information.  Later we check to see if it
 191   ;; is still clear, if so then all the cells have died.
 192   (store-match-data nil)
 193   (goto-beginning-of-buffer)
 194   ;; For speed declare all local variable outside the loop.
 195   (let (point char pivot living-neighbors list)
 196     (while (search-forward (life-life-string) nil t)
 197       (setq list life-neighbor-deltas
 198             living-neighbors 0
 199             pivot (1- (point)))
 200       (while list
 201         (setq point (+ pivot (car list))
 202               char (char-after point))
 203         (cond ((eq char (life-void-char))
 204                (subst-char-in-region point (1+ point)
 205                                      (life-void-char) 1 t))
 206               ((< char 3)
 207                (subst-char-in-region point (1+ point) char (1+ char) t))
 208               ((< char 9)
 209                (subst-char-in-region point (1+ point) char 9 t))
 210               ((>= char (life-life-char))
 211                (increment living-neighbors)))
 212         (setq list (cdr list)))
 213       (if (memq living-neighbors '(2 3))
 214           ()
 215         (subst-char-in-region pivot (1+ pivot)
 216                             (life-life-char) (life-death-char) t))))
 217   (if (null (match-beginning 0))
 218       (life-extinct-quit))
 219   (subst-char-in-region 1 (point-max) 9 (life-void-char) t)
 220   (subst-char-in-region 1 (point-max) 1 (life-void-char) t)
 221   (subst-char-in-region 1 (point-max) 2 (life-void-char) t)
 222   (subst-char-in-region 1 (point-max) (life-birth-char) (life-life-char) t)
 223   (subst-char-in-region 1 (point-max) (life-death-char) (life-void-char) t))
 224
 225 (defun life-expand-plane-if-needed ()
 226   (catch 'done
 227     (goto-beginning-of-buffer)
 228     (while (not (eobp))
 229       ;; check for life at beginning or end of line.  If found at
 230       ;; either end, expand at both ends,
 231       (cond ((or (eq (following-char) (life-life-char))
 232                  (eq (progn (end-of-line) (preceding-char)) (life-life-char)))
 233              (goto-beginning-of-buffer)
 234              (while (not (eobp))
 235                (insert (life-void-char))
 236                (end-of-line)
 237                (insert (life-void-char))
 238                (forward-char))
 239            (setq fill-column (+ 2 fill-column))
 240            (scroll-left 1)
 241            (life-compute-neighbor-deltas)
 242            (throw 'done t)))
 243       (forward-line)))
 244   (goto-beginning-of-buffer)
 245   ;; check for life within the first two lines of the buffer.
 246   ;; If present insert two lifeless lines at the beginning..
 247   (cond ((search-forward (life-life-string)
 248                          (+ (point) fill-column fill-column 2) t)
 249          (goto-beginning-of-buffer)
 250          (insert-char (life-void-char) fill-column)
 251          (insert ?\n)
 252          (insert-char (life-void-char) fill-column)
 253          (insert ?\n)
 254          (setq life-window-start (+ life-window-start fill-column 1))))
 255   (goto-end-of-buffer)
 256   ;; check for life within the last two lines of the buffer.
 257   ;; If present insert two lifeless lines at the end.
 258   (cond ((search-backward (life-life-string)
 259                           (- (point) fill-column fill-column 2) t)
 260          (goto-end-of-buffer)
 261          (insert-char (life-void-char) fill-column)
 262          (insert ?\n)
 263          (insert-char (life-void-char) fill-column)
 264          (insert ?\n)
 265          (setq life-window-start (+ life-window-start fill-column 1)))))
 266
 267 (defun life-display-generation (sleeptime)
 268   (goto-char life-window-start)
 269   (recenter 0)
 270   (sit-for sleeptime))
 271
 272 (defun life-extinct-quit ()
 273   (life-display-generation 0)
 274   (signal 'life-extinct nil))
 275
 276 (put 'life-extinct 'error-conditions '(life-extinct quit))
 277 (put 'life-extinct 'error-message "All life has perished")
 278
 279 (provide 'life)
 280
 281 ;;; life.el ends here