;; Copyright (C) 1988 Free Software Foundation, Inc.
;; Author: Kyle Jones <talos!kjones@uunet.uu.net>
-;; Keyword: games
+;; Keywords: games
;; This file is part of GNU Emacs.
;; along with GNU Emacs; see the file COPYING. If not, write to
;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+;;; Commentary:
+
+;; A demonstrator for John Horton Conway's "Life" cellular automaton
+;; in Emacs Lisp. Picks a random one of a set of interesting Life
+;; patterns and evolves it according to the familiar rules.
+
;;; Code:
(defconst life-patterns
(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)))
+(defmacro life-increment (variable) (list 'setq variable (list '1+ variable)))
;; list of numbers that tell how many characters to move to get to
;; Sadly, mode-line-format won't display numbers.
(defconst life-generation-string nil)
-(defun abs (n) (if (< n 0) (- n) n))
+(defvar life-initialized nil
+ "Non-nil if `life' has been run at least once.")
;;;###autoload
(defun life (&optional sleeptime)
arg non-nil from a program) is the number of seconds to sleep between
generations (this defaults to 1)."
(interactive "p")
+ (or life-initialized
+ (random t))
+ (setq life-initialized t)
(or sleeptime (setq sleeptime 1))
(life-setup)
(life-display-generation sleeptime)
(life-increment-generation)
(life-display-generation sleeptime)))))
-(fset 'life-mode 'life)
+(defalias 'life-mode 'life)
(put 'life-mode 'mode-class 'special)
-(random t)
-
(defun life-setup ()
(let (n)
(switch-to-buffer (get-buffer-create "*Life*") t)
;; stuff in the random pattern
(life-insert-random-pattern)
;; make sure (life-life-char) is used throughout
- (goto-beginning-of-buffer)
+ (goto-char (point-min))
(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)
+ (goto-char (point-min))
(setq n (/ (- fill-column (save-excursion (end-of-line) (point))) 2))
(while (not (eobp))
(indent-to n)
(setq n (/ (- (1- (window-height))
(count-lines (point-min) (point-max)))
2))
- (goto-beginning-of-buffer)
+ (goto-char (point-min))
(newline n)
- (goto-end-of-buffer)
+ (goto-char (point-max))
(newline n)
;; pad lines out to fill-column
- (goto-beginning-of-buffer)
+ (goto-char (point-min))
(while (not (eobp))
(end-of-line)
(indent-to fill-column)
(defun life-insert-random-pattern ()
(insert-rectangle
- (elt life-patterns (% (abs (random)) (length life-patterns))))
+ (elt life-patterns (random (length life-patterns))))
(insert ?\n))
(defun life-increment-generation ()
- (increment life-current-generation)
+ (life-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)
+ (goto-char (point-min))
;; For speed declare all local variable outside the loop.
(let (point char pivot living-neighbors list)
(while (search-forward (life-life-string) nil t)
((< char 9)
(subst-char-in-region point (1+ point) char 9 t))
((>= char (life-life-char))
- (increment living-neighbors)))
+ (life-increment living-neighbors)))
(setq list (cdr list)))
(if (memq living-neighbors '(2 3))
()
(defun life-expand-plane-if-needed ()
(catch 'done
- (goto-beginning-of-buffer)
+ (goto-char (point-min))
(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)
+ (goto-char (point-min))
(while (not (eobp))
(insert (life-void-char))
(end-of-line)
(life-compute-neighbor-deltas)
(throw 'done t)))
(forward-line)))
- (goto-beginning-of-buffer)
+ (goto-char (point-min))
;; 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)
+ (goto-char (point-min))
(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)
+ (goto-char (point-max))
;; 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)
+ (goto-char (point-max))
(insert-char (life-void-char) fill-column)
(insert ?\n)
(insert-char (life-void-char) fill-column)