Annotation of GNUtools/emacs/lisp/life.el, revision 1.1.1.1

1.1       root        1: ;; Conway's `Life' for GNU Emacs
                      2: ;; Copyright (C) 1988 Free Software Foundation, Inc.
                      3: ;; Contributed by Kyle Jones, [email protected]
                      4: 
                      5: ;; This file is part of GNU Emacs.
                      6: 
                      7: ;; GNU Emacs is free software; you can redistribute it and/or modify
                      8: ;; it under the terms of the GNU General Public License as published by
                      9: ;; the Free Software Foundation; either version 1, or (at your option)
                     10: ;; any later version.
                     11: 
                     12: ;; GNU Emacs is distributed in the hope that it will be useful,
                     13: ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
                     14: ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
                     15: ;; GNU General Public License for more details.
                     16: 
                     17: ;; You should have received a copy of the GNU General Public License
                     18: ;; along with GNU Emacs; see the file COPYING.  If not, write to
                     19: ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
                     20: 
                     21: (provide 'life)
                     22: 
                     23: (defconst life-patterns
                     24:   [("@@@" " @@" "@@@")
                     25:    ("@@@ @@@" "@@  @@ " "@@@ @@@")
                     26:    ("@@@ @@@" "@@   @@" "@@@ @@@")
                     27:    ("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@")
                     28:    ("@@@@@@@@@@")
                     29:    ("   @@@@@@@@@@       "
                     30:     "     @@@@@@@@@@     "
                     31:     "       @@@@@@@@@@   "
                     32:     "@@@@@@@@@@          "
                     33:     "@@@@@@@@@@          ")
                     34:    ("@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@")
                     35:    ("@               @" "@               @"  "@               @"
                     36:     "@               @" "@               @"  "@               @"
                     37:     "@               @" "@               @"  "@               @"
                     38:     "@               @" "@               @"  "@               @"
                     39:     "@               @" "@               @"  "@               @")
                     40:    ("@@               " " @@              " "  @@             "
                     41:     "   @@            " "    @@           " "     @@          "
                     42:     "      @@         " "       @@        " "        @@       "
                     43:     "         @@      " "          @@     " "           @@    "
                     44:     "            @@   " "             @@  " "              @@ "
                     45:     "               @@")
                     46:    ("@@@@@@@@@" "@   @   @" "@ @@@@@ @" "@ @   @ @" "@@@   @@@" 
                     47:     "@ @   @ @" "@ @@@@@ @" "@   @   @" "@@@@@@@@@")]
                     48:   "Vector of rectangles containing some Life startup patterns.")
                     49: 
                     50: ;; Macros are used macros for manifest constants instead of variables
                     51: ;; because the compiler will convert them to constants, which should
                     52: ;; eval faster than symbols.
                     53: ;;
                     54: ;; The (require) wrapping forces the compiler to eval these macros at
                     55: ;; compile time.  This would not be necessary if we did not use macros
                     56: ;; inside of macros, which the compiler doesn't seem to check for.
                     57: ;;
                     58: ;; Don't change any of the life-* macro constants unless you thoroughly
                     59: ;; understand the `life-grim-reaper' function.
                     60: (require
                     61:  (progn
                     62:    (defmacro life-life-char () ?@)
                     63:    (defmacro life-death-char () (1+ (life-life-char)))
                     64:    (defmacro life-birth-char () 3)
                     65:    (defmacro life-void-char () ?\ )
                     66: 
                     67:    (defmacro life-life-string () (char-to-string (life-life-char)))
                     68:    (defmacro life-death-string () (char-to-string (life-death-char)))
                     69:    (defmacro life-birth-string () (char-to-string (life-birth-char)))
                     70:    (defmacro life-void-string () (char-to-string (life-void-char)))
                     71:    (defmacro life-not-void-regexp () (concat "[^" (life-void-string) "\n]"))
                     72: 
                     73:    ;; try to optimize the (goto-char (point-min)) & (goto-char (point-max))
                     74:    ;; idioms.  This depends on goto-char's not griping if we underrshoot
                     75:    ;; or overshoot beginning or end of buffer.
                     76:    (defmacro goto-beginning-of-buffer () '(goto-char 1))
                     77:    (defmacro maxint () (lsh (lsh (lognot 0) 1) -1))
                     78:    (defmacro goto-end-of-buffer () '(goto-char (maxint)))
                     79: 
                     80:    (defmacro increment (variable) (list 'setq variable (list '1+ variable)))
                     81:    'life))
                     82: 
                     83: ;; list of numbers that tell how many characters to move to get to
                     84: ;; each of a cell's eight neighbors.
                     85: (defconst life-neighbor-deltas nil)
                     86: 
                     87: ;; window display always starts here.  Easier to deal with than
                     88: ;; (scroll-up) and (scroll-down) when trying to center the display.
                     89: (defconst life-window-start nil)
                     90: 
                     91: ;; For mode line
                     92: (defconst life-current-generation nil)
                     93: ;; Sadly, mode-line-format won't display numbers.
                     94: (defconst life-generation-string nil)
                     95: 
                     96: (defun abs (n) (if (< n 0) (- n) n))
                     97: 
                     98: (defun life (&optional sleeptime)
                     99:   "Run Conway's Life simulation.
                    100: The starting pattern is randomly selected.  Prefix arg (optional first arg
                    101: non-nil from a program) is the number of seconds to sleep between
                    102: generations (this defaults to 1)."
                    103:   (interactive "p")
                    104:   (or sleeptime (setq sleeptime 1))
                    105:   (life-setup)
                    106:   (life-display-generation sleeptime)
                    107:   (while t
                    108:     (let ((inhibit-quit t))
                    109:       (life-grim-reaper)
                    110:       (life-expand-plane-if-needed)
                    111:       (life-increment-generation)
                    112:       (life-display-generation sleeptime))))
                    113: 
                    114: (fset 'life-mode 'life)
                    115: (put 'life-mode 'mode-class 'special)
                    116: 
                    117: (random t)
                    118: 
                    119: (defun life-setup ()
                    120:   (let (n)
                    121:     (switch-to-buffer (get-buffer-create "*Life*") t)
                    122:     (erase-buffer)
                    123:     (kill-all-local-variables)
                    124:     (setq case-fold-search nil
                    125:          mode-name "Life"
                    126:          major-mode 'life-mode
                    127:          truncate-lines t
                    128:          life-current-generation 0
                    129:          life-generation-string "0"
                    130:          mode-line-buffer-identification '("Life: generation "
                    131:                                            life-generation-string)
                    132:          fill-column (1- (window-width))
                    133:          life-window-start 1)
                    134:     (buffer-flush-undo (current-buffer))
                    135:     ;; stuff in the random pattern
                    136:     (life-insert-random-pattern)
                    137:     ;; make sure (life-life-char) is used throughout
                    138:     (goto-beginning-of-buffer)
                    139:     (while (re-search-forward (life-not-void-regexp) nil t)
                    140:       (replace-match (life-life-string) t t))
                    141:     ;; center the pattern horizontally
                    142:     (goto-beginning-of-buffer)
                    143:     (setq n (/ (- fill-column (save-excursion (end-of-line) (point))) 2))
                    144:     (while (not (eobp))
                    145:       (indent-to n)
                    146:       (forward-line))
                    147:     ;; center the pattern vertically
                    148:     (setq n (/ (- (1- (window-height))
                    149:                  (count-lines (point-min) (point-max)))
                    150:               2))
                    151:     (goto-beginning-of-buffer)
                    152:     (newline n)
                    153:     (goto-end-of-buffer)
                    154:     (newline n)
                    155:     ;; pad lines out to fill-column
                    156:     (goto-beginning-of-buffer)
                    157:     (while (not (eobp))
                    158:       (end-of-line)
                    159:       (indent-to fill-column)
                    160:       (move-to-column fill-column)
                    161:       (delete-region (point) (progn (end-of-line) (point)))
                    162:       (forward-line))
                    163:     ;; expand tabs to spaces
                    164:     (untabify (point-min) (point-max))
                    165:     ;; before starting be sure the automaton has room to grow
                    166:     (life-expand-plane-if-needed)
                    167:     ;; compute initial neighbor deltas
                    168:     (life-compute-neighbor-deltas)))
                    169: 
                    170: (defun life-compute-neighbor-deltas ()
                    171:   (setq life-neighbor-deltas
                    172:        (list -1 (- fill-column)
                    173:              (- (1+ fill-column)) (- (+ 2 fill-column))
                    174:              1 fill-column (1+ fill-column)
                    175:              (+ 2 fill-column))))
                    176: 
                    177: (defun life-insert-random-pattern ()
                    178:   (insert-rectangle
                    179:    (elt life-patterns (% (abs (random)) (length life-patterns))))
                    180:   (insert ?\n))
                    181: 
                    182: (defun life-increment-generation ()
                    183:   (increment life-current-generation)
                    184:   (setq life-generation-string (int-to-string life-current-generation)))
                    185: 
                    186: (defun life-grim-reaper ()
                    187:   ;; Clear the match information.  Later we check to see if it
                    188:   ;; is still clear, if so then all the cells have died.
                    189:   (store-match-data nil)
                    190:   (goto-beginning-of-buffer)
                    191:   ;; For speed declare all local variable outside the loop.
                    192:   (let (point char pivot living-neighbors list)
                    193:     (while (search-forward (life-life-string) nil t)
                    194:       (setq list life-neighbor-deltas
                    195:            living-neighbors 0
                    196:            pivot (1- (point)))
                    197:       (while list
                    198:        (setq point (+ pivot (car list))
                    199:              char (char-after point))
                    200:        (cond ((eq char (life-void-char))
                    201:               (subst-char-in-region point (1+ point)
                    202:                                     (life-void-char) 1 t))
                    203:              ((< char 3)
                    204:               (subst-char-in-region point (1+ point) char (1+ char) t))
                    205:              ((< char 9)
                    206:               (subst-char-in-region point (1+ point) char 9 t))
                    207:              ((>= char (life-life-char))
                    208:               (increment living-neighbors)))
                    209:        (setq list (cdr list)))
                    210:       (if (memq living-neighbors '(2 3))
                    211:          ()
                    212:        (subst-char-in-region pivot (1+ pivot)
                    213:                            (life-life-char) (life-death-char) t))))
                    214:   (if (null (match-beginning 0))
                    215:       (life-extinct-quit))
                    216:   (subst-char-in-region 1 (point-max) 9 (life-void-char) t)
                    217:   (subst-char-in-region 1 (point-max) 1 (life-void-char) t)
                    218:   (subst-char-in-region 1 (point-max) 2 (life-void-char) t)
                    219:   (subst-char-in-region 1 (point-max) (life-birth-char) (life-life-char) t)
                    220:   (subst-char-in-region 1 (point-max) (life-death-char) (life-void-char) t))
                    221: 
                    222: (defun life-expand-plane-if-needed ()
                    223:   (catch 'done
                    224:     (goto-beginning-of-buffer)
                    225:     (while (not (eobp))
                    226:       ;; check for life at beginning or end of line.  If found at
                    227:       ;; either end, expand at both ends,
                    228:       (cond ((or (eq (following-char) (life-life-char))
                    229:                 (eq (progn (end-of-line) (preceding-char)) (life-life-char)))
                    230:             (goto-beginning-of-buffer)
                    231:             (while (not (eobp))
                    232:               (insert (life-void-char))
                    233:               (end-of-line)
                    234:               (insert (life-void-char))
                    235:               (forward-char))
                    236:           (setq fill-column (+ 2 fill-column))
                    237:           (scroll-left 1)
                    238:           (life-compute-neighbor-deltas)
                    239:           (throw 'done t)))
                    240:       (forward-line)))
                    241:   (goto-beginning-of-buffer)
                    242:   ;; check for life within the first two lines of the buffer.
                    243:   ;; If present insert two lifeless lines at the beginning..
                    244:   (cond ((search-forward (life-life-string)
                    245:                         (+ (point) fill-column fill-column 2) t)
                    246:         (goto-beginning-of-buffer)
                    247:         (insert-char (life-void-char) fill-column)
                    248:         (insert ?\n)
                    249:         (insert-char (life-void-char) fill-column)
                    250:         (insert ?\n)
                    251:         (setq life-window-start (+ life-window-start fill-column 1))))
                    252:   (goto-end-of-buffer)
                    253:   ;; check for life within the last two lines of the buffer.
                    254:   ;; If present insert two lifeless lines at the end.
                    255:   (cond ((search-backward (life-life-string)
                    256:                          (- (point) fill-column fill-column 2) t)
                    257:         (goto-end-of-buffer)
                    258:         (insert-char (life-void-char) fill-column)
                    259:         (insert ?\n)
                    260:         (insert-char (life-void-char) fill-column)
                    261:         (insert ?\n)
                    262:         (setq life-window-start (+ life-window-start fill-column 1)))))
                    263: 
                    264: (defun life-display-generation (sleeptime)
                    265:   (goto-char life-window-start)
                    266:   (recenter 0)
                    267:   (sit-for sleeptime))
                    268: 
                    269: (defun life-extinct-quit ()
                    270:   (life-display-generation 0)
                    271:   (signal 'life-extinct nil))
                    272: 
                    273: (put 'life-extinct 'error-conditions '(life-extinct quit))
                    274: (put 'life-extinct 'error-message "All life has perished")
                    275: 
                    276: 

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