lisp/play/life.el

   1 ;;; life.el --- John Horton Conway's `Life' game for GNU Emacs
   2
   3 ;; Author: Kyle Jones <talos!kjones@uunet.uu.net>
   4 ;; Last-Modified: 16 Mar 1992
   5 ;; Keyword: games
   6
   7 ;; Copyright (C) 1988 Free Software Foundation, Inc.
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software; you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation; either version 2, or (at your option)
  14 ;; any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs; see the file COPYING.  If not, write to
  23 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  24
  25 ;;; Code:
  26
  27 (defconst life-patterns
  28   [("@@@" " @@" "@@@")
  29    ("@@@ @@@" "@@  @@ " "@@@ @@@")
  30    ("@@@ @@@" "@@   @@" "@@@ @@@")
  31    ("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@")
  32    ("@@@@@@@@@@")
  33    ("   @@@@@@@@@@       "
  34     "     @@@@@@@@@@     "
  35     "       @@@@@@@@@@   "
  36     "@@@@@@@@@@          "
  37     "@@@@@@@@@@          ")
  38    ("@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@")
  39    ("@               @" "@               @"  "@               @"
  40     "@               @" "@               @"  "@               @"
  41     "@               @" "@               @"  "@               @"
  42     "@               @" "@               @"  "@               @"
  43     "@               @" "@               @"  "@               @")
  44    ("@@               " " @@              " "  @@             "
  45     "   @@            " "    @@           " "     @@          "
  46     "      @@         " "       @@        " "        @@       "
  47     "         @@      " "          @@     " "           @@    "
  48     "            @@   " "             @@  " "              @@ "
  49     "               @@")
  50    ("@@@@@@@@@" "@   @   @" "@ @@@@@ @" "@ @   @ @" "@@@   @@@"
  51     "@ @   @ @" "@ @@@@@ @" "@   @   @" "@@@@@@@@@")]
  52   "Vector of rectangles containing some Life startup patterns.")
  53
  54 ;; Macros are used macros for manifest constants instead of variables
  55 ;; because the compiler will convert them to constants, which should
  56 ;; eval faster than symbols.
  57 ;;
  58 ;; The (require) wrapping forces the compiler to eval these macros at
  59 ;; compile time.  This would not be necessary if we did not use macros
  60 ;; inside of macros, which the compiler doesn't seem to check for.
  61 ;;
  62 ;; Don't change any of the life-* macro constants unless you thoroughly
  63 ;; understand the `life-grim-reaper' function.
  64 (require
  65  (progn
  66    (defmacro life-life-char () ?@)
  67    (defmacro life-death-char () (1+ (life-life-char)))
  68    (defmacro life-birth-char () 3)
  69    (defmacro life-void-char () ?\ )
  70
  71    (defmacro life-life-string () (char-to-string (life-life-char)))
  72    (defmacro life-death-string () (char-to-string (life-death-char)))
  73    (defmacro life-birth-string () (char-to-string (life-birth-char)))
  74    (defmacro life-void-string () (char-to-string (life-void-char)))
  75    (defmacro life-not-void-regexp () (concat "[^" (life-void-string) "\n]"))
  76
  77    ;; try to optimize the (goto-char (point-min)) & (goto-char (point-max))
  78    ;; idioms.  This depends on goto-char's not griping if we underrshoot
  79    ;; or overshoot beginning or end of buffer.
  80    (defmacro goto-beginning-of-buffer () '(goto-char 1))
  81    (defmacro maxint () (lsh (lsh (lognot 0) 1) -1))
  82    (defmacro goto-end-of-buffer () '(goto-char (maxint)))
  83
  84    (defmacro increment (variable) (list 'setq variable (list '1+ variable)))
  85    'life))
  86
  87 ;; list of numbers that tell how many characters to move to get to
  88 ;; each of a cell's eight neighbors.
  89 (defconst life-neighbor-deltas nil)
  90
  91 ;; window display always starts here.  Easier to deal with than
  92 ;; (scroll-up) and (scroll-down) when trying to center the display.
  93 (defconst life-window-start nil)
  94
  95 ;; For mode line
  96 (defconst life-current-generation nil)
  97 ;; Sadly, mode-line-format won't display numbers.
  98 (defconst life-generation-string nil)
  99
 100 (defun abs (n) (if (< n 0) (- n) n))
 101
 102 (defun life (&optional sleeptime)
 103   "Run Conway's Life simulation.
 104 The starting pattern is randomly selected.  Prefix arg (optional first
 105 arg non-nil from a program) is the number of seconds to sleep between
 106 generations (this defaults to 1)."
 107   (interactive "p")
 108   (or sleeptime (setq sleeptime 1))
 109   (life-setup)
 110   (life-display-generation sleeptime)
 111   (while t
 112     (let ((inhibit-quit t))
 113       (life-grim-reaper)
 114       (life-expand-plane-if-needed)
 115       (life-increment-generation)
 116       (life-display-generation sleeptime))))
 117
 118 (fset 'life-mode 'life)
 119 (put 'life-mode 'mode-class 'special)
 120
 121 (random t)
 122
 123 (defun life-setup ()
 124   (let (n)
 125     (switch-to-buffer (get-buffer-create "*Life*") t)
 126     (erase-buffer)
 127     (kill-all-local-variables)
 128     (setq case-fold-search nil
 129           mode-name "Life"
 130           major-mode 'life-mode
 131           truncate-lines t
 132           life-current-generation 0
 133           life-generation-string "0"
 134           mode-line-buffer-identification '("Life: generation "
 135                                             life-generation-string)
 136           fill-column (1- (window-width))
 137           life-window-start 1)
 138     (buffer-disable-undo (current-buffer))
 139     ;; stuff in the random pattern
 140     (life-insert-random-pattern)
 141     ;; make sure (life-life-char) is used throughout
 142     (goto-beginning-of-buffer)
 143     (while (re-search-forward (life-not-void-regexp) nil t)
 144       (replace-match (life-life-string) t t))
 145     ;; center the pattern horizontally
 146     (goto-beginning-of-buffer)
 147     (setq n (/ (- fill-column (save-excursion (end-of-line) (point))) 2))
 148     (while (not (eobp))
 149       (indent-to n)
 150       (forward-line))
 151     ;; center the pattern vertically
 152     (setq n (/ (- (1- (window-height))
 153                   (count-lines (point-min) (point-max)))
 154                2))
 155     (goto-beginning-of-buffer)
 156     (newline n)
 157     (goto-end-of-buffer)
 158     (newline n)
 159     ;; pad lines out to fill-column
 160     (goto-beginning-of-buffer)
 161     (while (not (eobp))
 162       (end-of-line)
 163       (indent-to fill-column)
 164       (move-to-column fill-column)
 165       (delete-region (point) (progn (end-of-line) (point)))
 166       (forward-line))
 167     ;; expand tabs to spaces
 168     (untabify (point-min) (point-max))
 169     ;; before starting be sure the automaton has room to grow
 170     (life-expand-plane-if-needed)
 171     ;; compute initial neighbor deltas
 172     (life-compute-neighbor-deltas)))
 173
 174 (defun life-compute-neighbor-deltas ()
 175   (setq life-neighbor-deltas
 176         (list -1 (- fill-column)
 177               (- (1+ fill-column)) (- (+ 2 fill-column))
 178               1 fill-column (1+ fill-column)
 179               (+ 2 fill-column))))
 180
 181 (defun life-insert-random-pattern ()
 182   (insert-rectangle
 183    (elt life-patterns (% (abs (random)) (length life-patterns))))
 184   (insert ?\n))
 185
 186 (defun life-increment-generation ()
 187   (increment life-current-generation)
 188   (setq life-generation-string (int-to-string life-current-generation)))
 189
 190 (defun life-grim-reaper ()
 191   ;; Clear the match information.  Later we check to see if it
 192   ;; is still clear, if so then all the cells have died.
 193   (store-match-data nil)
 194   (goto-beginning-of-buffer)
 195   ;; For speed declare all local variable outside the loop.
 196   (let (point char pivot living-neighbors list)
 197     (while (search-forward (life-life-string) nil t)
 198       (setq list life-neighbor-deltas
 199             living-neighbors 0
 200             pivot (1- (point)))
 201       (while list
 202         (setq point (+ pivot (car list))
 203               char (char-after point))
 204         (cond ((eq char (life-void-char))
 205                (subst-char-in-region point (1+ point)
 206                                      (life-void-char) 1 t))
 207               ((< char 3)
 208                (subst-char-in-region point (1+ point) char (1+ char) t))
 209               ((< char 9)
 210                (subst-char-in-region point (1+ point) char 9 t))
 211               ((>= char (life-life-char))
 212                (increment living-neighbors)))
 213         (setq list (cdr list)))
 214       (if (memq living-neighbors '(2 3))
 215           ()
 216         (subst-char-in-region pivot (1+ pivot)
 217                             (life-life-char) (life-death-char) t))))
 218   (if (null (match-beginning 0))
 219       (life-extinct-quit))
 220   (subst-char-in-region 1 (point-max) 9 (life-void-char) t)
 221   (subst-char-in-region 1 (point-max) 1 (life-void-char) t)
 222   (subst-char-in-region 1 (point-max) 2 (life-void-char) t)
 223   (subst-char-in-region 1 (point-max) (life-birth-char) (life-life-char) t)
 224   (subst-char-in-region 1 (point-max) (life-death-char) (life-void-char) t))
 225
 226 (defun life-expand-plane-if-needed ()
 227   (catch 'done
 228     (goto-beginning-of-buffer)
 229     (while (not (eobp))
 230       ;; check for life at beginning or end of line.  If found at
 231       ;; either end, expand at both ends,
 232       (cond ((or (eq (following-char) (life-life-char))
 233                  (eq (progn (end-of-line) (preceding-char)) (life-life-char)))
 234              (goto-beginning-of-buffer)
 235              (while (not (eobp))
 236                (insert (life-void-char))
 237                (end-of-line)
 238                (insert (life-void-char))
 239                (forward-char))
 240            (setq fill-column (+ 2 fill-column))
 241            (scroll-left 1)
 242            (life-compute-neighbor-deltas)
 243            (throw 'done t)))
 244       (forward-line)))
 245   (goto-beginning-of-buffer)
 246   ;; check for life within the first two lines of the buffer.
 247   ;; If present insert two lifeless lines at the beginning..
 248   (cond ((search-forward (life-life-string)
 249                          (+ (point) fill-column fill-column 2) t)
 250          (goto-beginning-of-buffer)
 251          (insert-char (life-void-char) fill-column)
 252          (insert ?\n)
 253          (insert-char (life-void-char) fill-column)
 254          (insert ?\n)
 255          (setq life-window-start (+ life-window-start fill-column 1))))
 256   (goto-end-of-buffer)
 257   ;; check for life within the last two lines of the buffer.
 258   ;; If present insert two lifeless lines at the end.
 259   (cond ((search-backward (life-life-string)
 260                           (- (point) fill-column fill-column 2) t)
 261          (goto-end-of-buffer)
 262          (insert-char (life-void-char) fill-column)
 263          (insert ?\n)
 264          (insert-char (life-void-char) fill-column)
 265          (insert ?\n)
 266          (setq life-window-start (+ life-window-start fill-column 1)))))
 267
 268 (defun life-display-generation (sleeptime)
 269   (goto-char life-window-start)
 270   (recenter 0)
 271   (sit-for sleeptime))
 272
 273 (defun life-extinct-quit ()
 274   (life-display-generation 0)
 275   (signal 'life-extinct nil))
 276
 277 (put 'life-extinct 'error-conditions '(life-extinct quit))
 278 (put 'life-extinct 'error-message "All life has perished")
 279
 280 (provide 'life)
 281
 282 ;;; life.el ends here