1 ;;; life.el --- John Horton Conway's `Life' game for GNU Emacs
3 ;; Copyright (C) 1988, 2001-2012 Free Software Foundation, Inc.
5 ;; Author: Kyle Jones <kyleuunet.uu.net>
9 ;; This file is part of GNU Emacs.
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 3 of the License, or
14 ;; (at your option) any later version.
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.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
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.
34 ("@@@ @@@" "@@ @@ " "@@@ @@@")
35 ("@@@ @@@" "@@ @@" "@@@ @@@")
36 ("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@")
43 ("@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@")
55 ("@@@@@@@@@" "@ @ @" "@ @@@@@ @" "@ @ @ @" "@@@ @@@"
56 "@ @ @ @" "@ @@@@@ @" "@ @ @" "@@@@@@@@@")
77 ("@@@@@@@@ @@@@@ @@@ @@@@@@@ @@@@@")]
78 "Vector of rectangles containing some Life startup patterns.")
80 ;; Macros are used macros for manifest constants instead of variables
81 ;; because the compiler will convert them to constants, which should
82 ;; eval faster than symbols.
84 ;; Don't change any of the life-* macro constants unless you thoroughly
85 ;; understand the `life-grim-reaper' function.
87 (defmacro life-life-char
() ?
@)
88 (defmacro life-death-char
() (1+ (life-life-char)))
89 (defmacro life-birth-char
() 3)
90 (defmacro life-void-char
() ?\
)
92 (defmacro life-life-string
() (char-to-string (life-life-char)))
93 (defmacro life-death-string
() (char-to-string (life-death-char)))
94 (defmacro life-birth-string
() (char-to-string (life-birth-char)))
95 (defmacro life-void-string
() (char-to-string (life-void-char)))
96 (defmacro life-not-void-regexp
() (concat "[^" (life-void-string) "\n]"))
98 (defmacro life-increment
(variable) (list 'setq variable
(list '1+ variable
)))
101 ;; list of numbers that tell how many characters to move to get to
102 ;; each of a cell's eight neighbors.
103 (defvar life-neighbor-deltas nil
)
105 ;; window display always starts here. Easier to deal with than
106 ;; (scroll-up) and (scroll-down) when trying to center the display.
107 (defvar life-window-start nil
)
110 (defvar life-current-generation nil
)
111 ;; Sadly, mode-line-format won't display numbers.
112 (defvar life-generation-string nil
)
115 (defun life (&optional sleeptime
)
116 "Run Conway's Life simulation.
117 The starting pattern is randomly selected. Prefix arg (optional first
118 arg non-nil from a program) is the number of seconds to sleep between
119 generations (this defaults to 1)."
121 (or sleeptime
(setq sleeptime
1))
125 (let ((inhibit-quit t
))
126 (life-display-generation sleeptime
)
128 (life-expand-plane-if-needed)
129 (life-increment-generation)))))
131 (defalias 'life-mode
'life
)
132 (put 'life-mode
'mode-class
'special
)
136 (switch-to-buffer (get-buffer-create "*Life*") t
)
138 (kill-all-local-variables)
139 (setq case-fold-search nil
141 major-mode
'life-mode
143 show-trailing-whitespace nil
144 life-current-generation
0
145 life-generation-string
"0"
146 mode-line-buffer-identification
'("Life: generation "
147 life-generation-string
)
148 fill-column
(1- (window-width))
150 (buffer-disable-undo (current-buffer))
151 ;; stuff in the random pattern
152 (life-insert-random-pattern)
153 ;; make sure (life-life-char) is used throughout
154 (goto-char (point-min))
155 (while (re-search-forward (life-not-void-regexp) nil t
)
156 (replace-match (life-life-string) t t
))
157 ;; center the pattern horizontally
158 (goto-char (point-min))
159 (setq n
(/ (- fill-column
(line-end-position)) 2))
163 ;; center the pattern vertically
164 (setq n
(/ (- (1- (window-height))
165 (count-lines (point-min) (point-max)))
167 (goto-char (point-min))
169 (goto-char (point-max))
171 ;; pad lines out to fill-column
172 (goto-char (point-min))
175 (indent-to fill-column
)
176 (move-to-column fill-column
)
177 (delete-region (point) (progn (end-of-line) (point)))
179 ;; expand tabs to spaces
180 (untabify (point-min) (point-max))
181 ;; before starting be sure the automaton has room to grow
182 (life-expand-plane-if-needed)
183 ;; compute initial neighbor deltas
184 (life-compute-neighbor-deltas)))
186 (defun life-compute-neighbor-deltas ()
187 (setq life-neighbor-deltas
188 (list -
1 (- fill-column
)
189 (- (1+ fill-column
)) (- (+ 2 fill-column
))
190 1 fill-column
(1+ fill-column
)
193 (defun life-insert-random-pattern ()
195 (elt life-patterns
(random (length life-patterns
))))
198 (defun life-increment-generation ()
199 (life-increment life-current-generation
)
200 (setq life-generation-string
(int-to-string life-current-generation
)))
202 (defun life-grim-reaper ()
203 ;; Clear the match information. Later we check to see if it
204 ;; is still clear, if so then all the cells have died.
206 (goto-char (point-min))
207 ;; For speed declare all local variable outside the loop.
208 (let (point char pivot living-neighbors list
)
209 (while (search-forward (life-life-string) nil t
)
210 (setq list life-neighbor-deltas
214 (setq point
(+ pivot
(car list
))
215 char
(char-after point
))
216 (cond ((eq char
(life-void-char))
217 (subst-char-in-region point
(1+ point
)
218 (life-void-char) 1 t
))
220 (subst-char-in-region point
(1+ point
) char
(1+ char
) t
))
222 (subst-char-in-region point
(1+ point
) char
9 t
))
223 ((>= char
(life-life-char))
224 (life-increment living-neighbors
)))
225 (setq list
(cdr list
)))
226 (if (memq living-neighbors
'(2 3))
228 (subst-char-in-region pivot
(1+ pivot
)
229 (life-life-char) (life-death-char) t
))))
230 (if (null (match-beginning 0))
232 (subst-char-in-region 1 (point-max) 9 (life-void-char) t
)
233 (subst-char-in-region 1 (point-max) 1 (life-void-char) t
)
234 (subst-char-in-region 1 (point-max) 2 (life-void-char) t
)
235 (subst-char-in-region 1 (point-max) (life-birth-char) (life-life-char) t
)
236 (subst-char-in-region 1 (point-max) (life-death-char) (life-void-char) t
))
238 (defun life-expand-plane-if-needed ()
240 (goto-char (point-min))
242 ;; check for life at beginning or end of line. If found at
243 ;; either end, expand at both ends,
244 (cond ((or (eq (following-char) (life-life-char))
245 (eq (progn (end-of-line) (preceding-char)) (life-life-char)))
246 (goto-char (point-min))
248 (insert (life-void-char))
250 (insert (life-void-char))
252 (setq fill-column
(+ 2 fill-column
))
254 (life-compute-neighbor-deltas)
257 (goto-char (point-min))
258 ;; check for life within the first two lines of the buffer.
259 ;; If present insert two lifeless lines at the beginning..
260 (cond ((search-forward (life-life-string)
261 (+ (point) fill-column fill-column
2) t
)
262 (goto-char (point-min))
263 (insert-char (life-void-char) fill-column
)
265 (insert-char (life-void-char) fill-column
)
267 (setq life-window-start
(+ life-window-start fill-column
1))))
268 (goto-char (point-max))
269 ;; check for life within the last two lines of the buffer.
270 ;; If present insert two lifeless lines at the end.
271 (cond ((search-backward (life-life-string)
272 (- (point) fill-column fill-column
2) t
)
273 (goto-char (point-max))
274 (insert-char (life-void-char) fill-column
)
276 (insert-char (life-void-char) fill-column
)
278 (setq life-window-start
(+ life-window-start fill-column
1)))))
280 (defun life-display-generation (sleeptime)
281 (goto-char life-window-start
)
284 ;; Redisplay; if the user has hit a key, exit the loop.
285 (or (and (sit-for sleeptime
) (< 0 sleeptime
))
286 (not (input-pending-p))
287 (throw 'life-exit nil
)))
289 (defun life-extinct-quit ()
290 (life-display-generation 0)
291 (signal 'life-extinct nil
))
293 (put 'life-extinct
'error-conditions
'(life-extinct quit
))
294 (put 'life-extinct
'error-message
"All life has perished")
298 ;;; life.el ends here