1 ;;; life.el --- John Horton Conway's `Life' game for GNU Emacs
3 ;; Copyright (C) 1988 Free Software Foundation, Inc.
5 ;; Author: Kyle Jones <talos!kjones@uunet.uu.net>
8 ;; This file is part of GNU Emacs.
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)
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.
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.
26 ;; A demonstrator for John Horton Conway's "Life" cellular automaton
27 ;; in Emacs Lisp. Picks a random one of a set of interesting Life
28 ;; patterns and evolves it according to the familiar rules.
32 (defconst life-patterns
34 ("@@@ @@@" "@@ @@ " "@@@ @@@")
35 ("@@@ @@@" "@@ @@" "@@@ @@@")
36 ("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@")
43 ("@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@")
55 ("@@@@@@@@@" "@ @ @" "@ @@@@@ @" "@ @ @ @" "@@@ @@@"
56 "@ @ @ @" "@ @@@@@ @" "@ @ @" "@@@@@@@@@")]
57 "Vector of rectangles containing some Life startup patterns.")
59 ;; Macros are used macros for manifest constants instead of variables
60 ;; because the compiler will convert them to constants, which should
61 ;; eval faster than symbols.
63 ;; Don't change any of the life-* macro constants unless you thoroughly
64 ;; understand the `life-grim-reaper' function.
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
() ?\
)
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]"))
77 (defmacro life-increment
(variable) (list 'setq variable
(list '1+ variable
)))
80 ;; list of numbers that tell how many characters to move to get to
81 ;; each of a cell's eight neighbors.
82 (defconst life-neighbor-deltas nil
)
84 ;; window display always starts here. Easier to deal with than
85 ;; (scroll-up) and (scroll-down) when trying to center the display.
86 (defconst life-window-start nil
)
89 (defconst life-current-generation nil
)
90 ;; Sadly, mode-line-format won't display numbers.
91 (defconst life-generation-string nil
)
93 (defvar life-initialized nil
94 "Non-nil if `life' has been run at least once.")
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)."
105 (setq life-initialized t
)
106 (or sleeptime
(setq sleeptime
1))
108 (life-display-generation sleeptime
)
111 (let ((inhibit-quit t
))
113 (life-expand-plane-if-needed)
114 (life-increment-generation)
115 (life-display-generation sleeptime
)))))
117 (defalias 'life-mode
'life
)
118 (put 'life-mode
'mode-class
'special
)
122 (switch-to-buffer (get-buffer-create "*Life*") t
)
124 (kill-all-local-variables)
125 (setq case-fold-search nil
127 major-mode
'life-mode
129 life-current-generation
0
130 life-generation-string
"0"
131 mode-line-buffer-identification
'("Life: generation "
132 life-generation-string
)
133 fill-column
(1- (window-width))
135 (buffer-disable-undo (current-buffer))
136 ;; stuff in the random pattern
137 (life-insert-random-pattern)
138 ;; make sure (life-life-char) is used throughout
139 (goto-char (point-min))
140 (while (re-search-forward (life-not-void-regexp) nil t
)
141 (replace-match (life-life-string) t t
))
142 ;; center the pattern horizontally
143 (goto-char (point-min))
144 (setq n
(/ (- fill-column
(save-excursion (end-of-line) (point))) 2))
148 ;; center the pattern vertically
149 (setq n
(/ (- (1- (window-height))
150 (count-lines (point-min) (point-max)))
152 (goto-char (point-min))
154 (goto-char (point-max))
156 ;; pad lines out to fill-column
157 (goto-char (point-min))
160 (indent-to fill-column
)
161 (move-to-column fill-column
)
162 (delete-region (point) (progn (end-of-line) (point)))
164 ;; expand tabs to spaces
165 (untabify (point-min) (point-max))
166 ;; before starting be sure the automaton has room to grow
167 (life-expand-plane-if-needed)
168 ;; compute initial neighbor deltas
169 (life-compute-neighbor-deltas)))
171 (defun life-compute-neighbor-deltas ()
172 (setq life-neighbor-deltas
173 (list -
1 (- fill-column
)
174 (- (1+ fill-column
)) (- (+ 2 fill-column
))
175 1 fill-column
(1+ fill-column
)
178 (defun life-insert-random-pattern ()
180 (elt life-patterns
(random (length life-patterns
))))
183 (defun life-increment-generation ()
184 (life-increment life-current-generation
)
185 (setq life-generation-string
(int-to-string life-current-generation
)))
187 (defun life-grim-reaper ()
188 ;; Clear the match information. Later we check to see if it
189 ;; is still clear, if so then all the cells have died.
190 (store-match-data nil
)
191 (goto-char (point-min))
192 ;; For speed declare all local variable outside the loop.
193 (let (point char pivot living-neighbors list
)
194 (while (search-forward (life-life-string) nil t
)
195 (setq list life-neighbor-deltas
199 (setq point
(+ pivot
(car list
))
200 char
(char-after point
))
201 (cond ((eq char
(life-void-char))
202 (subst-char-in-region point
(1+ point
)
203 (life-void-char) 1 t
))
205 (subst-char-in-region point
(1+ point
) char
(1+ char
) t
))
207 (subst-char-in-region point
(1+ point
) char
9 t
))
208 ((>= char
(life-life-char))
209 (life-increment living-neighbors
)))
210 (setq list
(cdr list
)))
211 (if (memq living-neighbors
'(2 3))
213 (subst-char-in-region pivot
(1+ pivot
)
214 (life-life-char) (life-death-char) t
))))
215 (if (null (match-beginning 0))
217 (subst-char-in-region 1 (point-max) 9 (life-void-char) t
)
218 (subst-char-in-region 1 (point-max) 1 (life-void-char) t
)
219 (subst-char-in-region 1 (point-max) 2 (life-void-char) t
)
220 (subst-char-in-region 1 (point-max) (life-birth-char) (life-life-char) t
)
221 (subst-char-in-region 1 (point-max) (life-death-char) (life-void-char) t
))
223 (defun life-expand-plane-if-needed ()
225 (goto-char (point-min))
227 ;; check for life at beginning or end of line. If found at
228 ;; either end, expand at both ends,
229 (cond ((or (eq (following-char) (life-life-char))
230 (eq (progn (end-of-line) (preceding-char)) (life-life-char)))
231 (goto-char (point-min))
233 (insert (life-void-char))
235 (insert (life-void-char))
237 (setq fill-column
(+ 2 fill-column
))
239 (life-compute-neighbor-deltas)
242 (goto-char (point-min))
243 ;; check for life within the first two lines of the buffer.
244 ;; If present insert two lifeless lines at the beginning..
245 (cond ((search-forward (life-life-string)
246 (+ (point) fill-column fill-column
2) t
)
247 (goto-char (point-min))
248 (insert-char (life-void-char) fill-column
)
250 (insert-char (life-void-char) fill-column
)
252 (setq life-window-start
(+ life-window-start fill-column
1))))
253 (goto-char (point-max))
254 ;; check for life within the last two lines of the buffer.
255 ;; If present insert two lifeless lines at the end.
256 (cond ((search-backward (life-life-string)
257 (- (point) fill-column fill-column
2) t
)
258 (goto-char (point-max))
259 (insert-char (life-void-char) fill-column
)
261 (insert-char (life-void-char) fill-column
)
263 (setq life-window-start
(+ life-window-start fill-column
1)))))
265 (defun life-display-generation (sleeptime)
266 (goto-char life-window-start
)
269 ;; Redisplay; if the user has hit a key, exit the loop.
270 (or (eq t
(sit-for sleeptime
))
271 (throw 'life-exit nil
)))
273 (defun life-extinct-quit ()
274 (life-display-generation 0)
275 (signal 'life-extinct nil
))
277 (put 'life-extinct
'error-conditions
'(life-extinct quit
))
278 (put 'life-extinct
'error-message
"All life has perished")
282 ;;; life.el ends here