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date Mon, 13 Aug 2007 08:45:50 +0200
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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 ;; Keywords: games
7
8 ;; This file is part of XEmacs.
9
10 ;; XEmacs is free software; you can redistribute it and/or modify it
11 ;; 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 ;; XEmacs is distributed in the hope that it will be useful, but
16 ;; WITHOUT ANY WARRANTY; without even the implied warranty of
17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 ;; General Public License for more details.
19
20 ;; You should have received a copy of the GNU General Public License
21 ;; along with XEmacs; see the file COPYING. If not, write to the Free
22 ;; Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
23
24 ;;; Synched up with: FSF 19.30.
25
26 ;;; Commentary:
27
28 ;; A demonstrator for John Horton Conway's "Life" cellular automaton
29 ;; in Emacs Lisp. Picks a random one of a set of interesting Life
30 ;; patterns and evolves it according to the familiar rules.
31
32 ;;; Code:
33
34 (defconst life-patterns
35 [("@@@" " @@" "@@@")
36 ("@@@ @@@" "@@ @@ " "@@@ @@@")
37 ("@@@ @@@" "@@ @@" "@@@ @@@")
38 ("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@")
39 ("@@@@@@@@@@")
40 (" @@@@@@@@@@ "
41 " @@@@@@@@@@ "
42 " @@@@@@@@@@ "
43 "@@@@@@@@@@ "
44 "@@@@@@@@@@ ")
45 ("@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@")
46 ("@ @" "@ @" "@ @"
47 "@ @" "@ @" "@ @"
48 "@ @" "@ @" "@ @"
49 "@ @" "@ @" "@ @"
50 "@ @" "@ @" "@ @")
51 ("@@ " " @@ " " @@ "
52 " @@ " " @@ " " @@ "
53 " @@ " " @@ " " @@ "
54 " @@ " " @@ " " @@ "
55 " @@ " " @@ " " @@ "
56 " @@")
57 ("@@@@@@@@@" "@ @ @" "@ @@@@@ @" "@ @ @ @" "@@@ @@@"
58 "@ @ @ @" "@ @@@@@ @" "@ @ @" "@@@@@@@@@")]
59 "Vector of rectangles containing some Life startup patterns.")
60
61 ;; Macros are used macros for manifest constants instead of variables
62 ;; because the compiler will convert them to constants, which should
63 ;; eval faster than symbols.
64 ;;
65 ;; Don't change any of the life-* macro constants unless you thoroughly
66 ;; understand the `life-grim-reaper' function.
67
68 (defmacro life-life-char () ?@)
69 (defmacro life-death-char () (1+ (life-life-char)))
70 (defmacro life-birth-char () 3)
71 (defmacro life-void-char () ?\ )
72
73 (defmacro life-life-string () (char-to-string (life-life-char)))
74 (defmacro life-death-string () (char-to-string (life-death-char)))
75 (defmacro life-birth-string () (char-to-string (life-birth-char)))
76 (defmacro life-void-string () (char-to-string (life-void-char)))
77 (defmacro life-not-void-regexp () (concat "[^" (life-void-string) "\n]"))
78
79 (defmacro life-increment (variable) (list 'setq variable (list '1+ variable)))
80
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 (defvar life-initialized nil
96 "Non-nil if `life' has been run at least once.")
97
98 ;;;###autoload
99 (defun life (&optional sleeptime)
100 "Run Conway's Life simulation.
101 The starting pattern is randomly selected. Prefix arg (optional first
102 arg non-nil from a program) is the number of seconds to sleep between
103 generations (this defaults to 1)."
104 (interactive "p")
105 (or life-initialized
106 (random t))
107 (setq life-initialized t)
108 (or sleeptime (setq sleeptime 1))
109 (life-setup)
110 (life-display-generation sleeptime)
111 (catch 'life-exit
112 (while t
113 (let ((inhibit-quit t))
114 (life-grim-reaper)
115 (life-expand-plane-if-needed)
116 (life-increment-generation)
117 (life-display-generation sleeptime)))))
118
119 (defalias 'life-mode 'life)
120 (put 'life-mode 'mode-class 'special)
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 ;; XEmacs change:
128 (set-specifier scrollbar-height 0 (current-buffer))
129 (set-specifier scrollbar-width 0 (current-buffer))
130 (setq case-fold-search nil
131 mode-name "Life"
132 major-mode 'life-mode
133 truncate-lines t
134 life-current-generation 0
135 life-generation-string "0"
136 mode-line-buffer-identification '("Life: generation "
137 life-generation-string)
138 fill-column (1- (window-width))
139 life-window-start 1)
140 (buffer-disable-undo (current-buffer))
141 ;; stuff in the random pattern
142 (life-insert-random-pattern)
143 ;; make sure (life-life-char) is used throughout
144 (goto-char (point-min))
145 (while (re-search-forward (life-not-void-regexp) nil t)
146 (replace-match (life-life-string) t t))
147 ;; center the pattern horizontally
148 (goto-char (point-min))
149 (setq n (/ (- fill-column (save-excursion (end-of-line) (point))) 2))
150 (while (not (eobp))
151 (indent-to n)
152 (forward-line))
153 ;; center the pattern vertically
154 (setq n (/ (- (1- (window-height))
155 (count-lines (point-min) (point-max)))
156 2))
157 (goto-char (point-min))
158 (newline n)
159 (goto-char (point-max))
160 (newline n)
161 ;; pad lines out to fill-column
162 (goto-char (point-min))
163 (while (not (eobp))
164 (end-of-line)
165 (indent-to fill-column)
166 (move-to-column fill-column)
167 (delete-region (point) (progn (end-of-line) (point)))
168 (forward-line))
169 ;; expand tabs to spaces
170 (untabify (point-min) (point-max))
171 ;; before starting be sure the automaton has room to grow
172 (life-expand-plane-if-needed)
173 ;; compute initial neighbor deltas
174 (life-compute-neighbor-deltas)))
175
176 (defun life-compute-neighbor-deltas ()
177 (setq life-neighbor-deltas
178 (list -1 (- fill-column)
179 (- (1+ fill-column)) (- (+ 2 fill-column))
180 1 fill-column (1+ fill-column)
181 (+ 2 fill-column))))
182
183 (defun life-insert-random-pattern ()
184 (insert-rectangle
185 (elt life-patterns (random (length life-patterns))))
186 (insert ?\n))
187
188 (defun life-increment-generation ()
189 (life-increment life-current-generation)
190 (setq life-generation-string (int-to-string life-current-generation)))
191
192 (defun life-grim-reaper ()
193 ;; Clear the match information. Later we check to see if it
194 ;; is still clear, if so then all the cells have died.
195 (store-match-data nil)
196 (goto-char (point-min))
197 ;; For speed declare all local variable outside the loop.
198 (let (point char pivot living-neighbors list)
199 (while (search-forward (life-life-string) nil t)
200 (setq list life-neighbor-deltas
201 living-neighbors 0
202 pivot (1- (point)))
203 (while list
204 (setq point (+ pivot (car list))
205 char (char-after point))
206 (cond ((eq char (life-void-char))
207 (subst-char-in-region point (1+ point)
208 (life-void-char) 1 t))
209 ((< char 3)
210 (subst-char-in-region point (1+ point) char (1+ char) t))
211 ((< char 9)
212 (subst-char-in-region point (1+ point) char 9 t))
213 ((>= char (life-life-char))
214 (life-increment living-neighbors)))
215 (setq list (cdr list)))
216 (if (memq living-neighbors '(2 3))
217 ()
218 (subst-char-in-region pivot (1+ pivot)
219 (life-life-char) (life-death-char) t))))
220 (if (null (match-beginning 0))
221 (life-extinct-quit))
222 (subst-char-in-region 1 (point-max) 9 (life-void-char) t)
223 (subst-char-in-region 1 (point-max) 1 (life-void-char) t)
224 (subst-char-in-region 1 (point-max) 2 (life-void-char) t)
225 (subst-char-in-region 1 (point-max) (life-birth-char) (life-life-char) t)
226 (subst-char-in-region 1 (point-max) (life-death-char) (life-void-char) t))
227
228 (defun life-expand-plane-if-needed ()
229 (catch 'done
230 (goto-char (point-min))
231 (while (not (eobp))
232 ;; check for life at beginning or end of line. If found at
233 ;; either end, expand at both ends,
234 (cond ((or (eq (following-char) (life-life-char))
235 (eq (progn (end-of-line) (preceding-char)) (life-life-char)))
236 (goto-char (point-min))
237 (while (not (eobp))
238 (insert (life-void-char))
239 (end-of-line)
240 (insert (life-void-char))
241 (forward-char))
242 (setq fill-column (+ 2 fill-column))
243 (scroll-left 1)
244 (life-compute-neighbor-deltas)
245 (throw 'done t)))
246 (forward-line)))
247 (goto-char (point-min))
248 ;; check for life within the first two lines of the buffer.
249 ;; If present insert two lifeless lines at the beginning..
250 (cond ((search-forward (life-life-string)
251 (+ (point) fill-column fill-column 2) t)
252 (goto-char (point-min))
253 (insert-char (life-void-char) fill-column)
254 (insert ?\n)
255 (insert-char (life-void-char) fill-column)
256 (insert ?\n)
257 (setq life-window-start (+ life-window-start fill-column 1))))
258 (goto-char (point-max))
259 ;; check for life within the last two lines of the buffer.
260 ;; If present insert two lifeless lines at the end.
261 (cond ((search-backward (life-life-string)
262 (- (point) fill-column fill-column 2) t)
263 (goto-char (point-max))
264 (insert-char (life-void-char) fill-column)
265 (insert ?\n)
266 (insert-char (life-void-char) fill-column)
267 (insert ?\n)
268 (setq life-window-start (+ life-window-start fill-column 1)))))
269
270 (defun life-display-generation (sleeptime)
271 (goto-char life-window-start)
272 (recenter 0)
273
274 ;; Redisplay; if the user has hit a key, exit the loop.
275 (or (eq t (sit-for sleeptime))
276 (throw 'life-exit nil)))
277
278 (defun life-extinct-quit ()
279 (life-display-generation 0)
280 (signal 'life-extinct nil))
281
282 ;; XEmacs change
283 (define-error 'life-extinct "All life has perished" 'quit)
284
285 (provide 'life)
286
287 ;;; life.el ends here