4.4BSD/usr/src/contrib/emacs-18.57/lisp/life.el
;; Conway's `Life' for GNU Emacs
;; Copyright (C) 1988 Free Software Foundation, Inc.
;; Contributed by Kyle Jones, talos!kjones@uunet.uu.net
;; This file is part of GNU Emacs.
;; GNU Emacs is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 1, or (at your option)
;; any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING. If not, write to
;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
(provide 'life)
(defconst life-patterns
[("@@@" " @@" "@@@")
("@@@ @@@" "@@ @@ " "@@@ @@@")
("@@@ @@@" "@@ @@" "@@@ @@@")
("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@")
("@@@@@@@@@@")
(" @@@@@@@@@@ "
" @@@@@@@@@@ "
" @@@@@@@@@@ "
"@@@@@@@@@@ "
"@@@@@@@@@@ ")
("@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@")
("@ @" "@ @" "@ @"
"@ @" "@ @" "@ @"
"@ @" "@ @" "@ @"
"@ @" "@ @" "@ @"
"@ @" "@ @" "@ @")
("@@ " " @@ " " @@ "
" @@ " " @@ " " @@ "
" @@ " " @@ " " @@ "
" @@ " " @@ " " @@ "
" @@ " " @@ " " @@ "
" @@")
("@@@@@@@@@" "@ @ @" "@ @@@@@ @" "@ @ @ @" "@@@ @@@"
"@ @ @ @" "@ @@@@@ @" "@ @ @" "@@@@@@@@@")]
"Vector of rectangles containing some Life startup patterns.")
;; Macros are used macros for manifest constants instead of variables
;; because the compiler will convert them to constants, which should
;; eval faster than symbols.
;;
;; The (require) wrapping forces the compiler to eval these macros at
;; compile time. This would not be necessary if we did not use macros
;; inside of macros, which the compiler doesn't seem to check for.
;;
;; Don't change any of the life-* macro constants unless you thoroughly
;; understand the `life-grim-reaper' function.
(require
(progn
(defmacro life-life-char () ?@)
(defmacro life-death-char () (1+ (life-life-char)))
(defmacro life-birth-char () 3)
(defmacro life-void-char () ?\ )
(defmacro life-life-string () (char-to-string (life-life-char)))
(defmacro life-death-string () (char-to-string (life-death-char)))
(defmacro life-birth-string () (char-to-string (life-birth-char)))
(defmacro life-void-string () (char-to-string (life-void-char)))
(defmacro life-not-void-regexp () (concat "[^" (life-void-string) "\n]"))
;; try to optimize the (goto-char (point-min)) & (goto-char (point-max))
;; idioms. This depends on goto-char's not griping if we underrshoot
;; or overshoot beginning or end of buffer.
(defmacro goto-beginning-of-buffer () '(goto-char 1))
(defmacro maxint () (lsh (lsh (lognot 0) 1) -1))
(defmacro goto-end-of-buffer () '(goto-char (maxint)))
(defmacro increment (variable) (list 'setq variable (list '1+ variable)))
'life))
;; list of numbers that tell how many characters to move to get to
;; each of a cell's eight neighbors.
(defconst life-neighbor-deltas nil)
;; window display always starts here. Easier to deal with than
;; (scroll-up) and (scroll-down) when trying to center the display.
(defconst life-window-start nil)
;; For mode line
(defconst life-current-generation nil)
;; Sadly, mode-line-format won't display numbers.
(defconst life-generation-string nil)
(defun abs (n) (if (< n 0) (- n) n))
(defun life (&optional sleeptime)
"Run Conway's Life simulation.
The starting pattern is randomly selected. Prefix arg (optional first arg
non-nil from a program) is the number of seconds to sleep between
generations (this defaults to 1)."
(interactive "p")
(or sleeptime (setq sleeptime 1))
(life-setup)
(life-display-generation sleeptime)
(while t
(let ((inhibit-quit t))
(life-grim-reaper)
(life-expand-plane-if-needed)
(life-increment-generation)
(life-display-generation sleeptime))))
(fset 'life-mode 'life)
(put 'life-mode 'mode-class 'special)
(random t)
(defun life-setup ()
(let (n)
(switch-to-buffer (get-buffer-create "*Life*") t)
(erase-buffer)
(kill-all-local-variables)
(setq case-fold-search nil
mode-name "Life"
major-mode 'life-mode
truncate-lines t
life-current-generation 0
life-generation-string "0"
mode-line-buffer-identification '("Life: generation "
life-generation-string)
fill-column (1- (window-width))
life-window-start 1)
(buffer-flush-undo (current-buffer))
;; stuff in the random pattern
(life-insert-random-pattern)
;; make sure (life-life-char) is used throughout
(goto-beginning-of-buffer)
(while (re-search-forward (life-not-void-regexp) nil t)
(replace-match (life-life-string) t t))
;; center the pattern horizontally
(goto-beginning-of-buffer)
(setq n (/ (- fill-column (save-excursion (end-of-line) (point))) 2))
(while (not (eobp))
(indent-to n)
(forward-line))
;; center the pattern vertically
(setq n (/ (- (1- (window-height))
(count-lines (point-min) (point-max)))
2))
(goto-beginning-of-buffer)
(newline n)
(goto-end-of-buffer)
(newline n)
;; pad lines out to fill-column
(goto-beginning-of-buffer)
(while (not (eobp))
(end-of-line)
(indent-to fill-column)
(move-to-column fill-column)
(delete-region (point) (progn (end-of-line) (point)))
(forward-line))
;; expand tabs to spaces
(untabify (point-min) (point-max))
;; before starting be sure the automaton has room to grow
(life-expand-plane-if-needed)
;; compute initial neighbor deltas
(life-compute-neighbor-deltas)))
(defun life-compute-neighbor-deltas ()
(setq life-neighbor-deltas
(list -1 (- fill-column)
(- (1+ fill-column)) (- (+ 2 fill-column))
1 fill-column (1+ fill-column)
(+ 2 fill-column))))
(defun life-insert-random-pattern ()
(insert-rectangle
(elt life-patterns (% (abs (random)) (length life-patterns))))
(insert ?\n))
(defun life-increment-generation ()
(increment life-current-generation)
(setq life-generation-string (int-to-string life-current-generation)))
(defun life-grim-reaper ()
;; Clear the match information. Later we check to see if it
;; is still clear, if so then all the cells have died.
(store-match-data nil)
(goto-beginning-of-buffer)
;; For speed declare all local variable outside the loop.
(let (point char pivot living-neighbors list)
(while (search-forward (life-life-string) nil t)
(setq list life-neighbor-deltas
living-neighbors 0
pivot (1- (point)))
(while list
(setq point (+ pivot (car list))
char (char-after point))
(cond ((eq char (life-void-char))
(subst-char-in-region point (1+ point)
(life-void-char) 1 t))
((< char 3)
(subst-char-in-region point (1+ point) char (1+ char) t))
((< char 9)
(subst-char-in-region point (1+ point) char 9 t))
((>= char (life-life-char))
(increment living-neighbors)))
(setq list (cdr list)))
(if (memq living-neighbors '(2 3))
()
(subst-char-in-region pivot (1+ pivot)
(life-life-char) (life-death-char) t))))
(if (null (match-beginning 0))
(life-extinct-quit))
(subst-char-in-region 1 (point-max) 9 (life-void-char) t)
(subst-char-in-region 1 (point-max) 1 (life-void-char) t)
(subst-char-in-region 1 (point-max) 2 (life-void-char) t)
(subst-char-in-region 1 (point-max) (life-birth-char) (life-life-char) t)
(subst-char-in-region 1 (point-max) (life-death-char) (life-void-char) t))
(defun life-expand-plane-if-needed ()
(catch 'done
(goto-beginning-of-buffer)
(while (not (eobp))
;; check for life at beginning or end of line. If found at
;; either end, expand at both ends,
(cond ((or (eq (following-char) (life-life-char))
(eq (progn (end-of-line) (preceding-char)) (life-life-char)))
(goto-beginning-of-buffer)
(while (not (eobp))
(insert (life-void-char))
(end-of-line)
(insert (life-void-char))
(forward-char))
(setq fill-column (+ 2 fill-column))
(scroll-left 1)
(life-compute-neighbor-deltas)
(throw 'done t)))
(forward-line)))
(goto-beginning-of-buffer)
;; check for life within the first two lines of the buffer.
;; If present insert two lifeless lines at the beginning..
(cond ((search-forward (life-life-string)
(+ (point) fill-column fill-column 2) t)
(goto-beginning-of-buffer)
(insert-char (life-void-char) fill-column)
(insert ?\n)
(insert-char (life-void-char) fill-column)
(insert ?\n)
(setq life-window-start (+ life-window-start fill-column 1))))
(goto-end-of-buffer)
;; check for life within the last two lines of the buffer.
;; If present insert two lifeless lines at the end.
(cond ((search-backward (life-life-string)
(- (point) fill-column fill-column 2) t)
(goto-end-of-buffer)
(insert-char (life-void-char) fill-column)
(insert ?\n)
(insert-char (life-void-char) fill-column)
(insert ?\n)
(setq life-window-start (+ life-window-start fill-column 1)))))
(defun life-display-generation (sleeptime)
(goto-char life-window-start)
(recenter 0)
(sit-for sleeptime))
(defun life-extinct-quit ()
(life-display-generation 0)
(signal 'life-extinct nil))
(put 'life-extinct 'error-conditions '(life-extinct quit))
(put 'life-extinct 'error-message "All life has perished")