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Annotation of 43BSD/contrib/emacs/lisp/compare-w.el, revision 1.1.1.1

1.1       root        1: ;; Compare text between windows for Emacs.
                      2: ;; Copyright (C) 1985 Richard M. Stallman.
                      3: 
                      4: ;; This file is part of GNU Emacs.
                      5: 
                      6: ;; GNU Emacs is distributed in the hope that it will be useful,
                      7: ;; but WITHOUT ANY WARRANTY.  No author or distributor
                      8: ;; accepts responsibility to anyone for the consequences of using it
                      9: ;; or for whether it serves any particular purpose or works at all,
                     10: ;; unless he says so in writing.  Refer to the GNU Emacs General Public
                     11: ;; License for full details.
                     12: 
                     13: ;; Everyone is granted permission to copy, modify and redistribute
                     14: ;; GNU Emacs, but only under the conditions described in the
                     15: ;; GNU Emacs General Public License.   A copy of this license is
                     16: ;; supposed to have been given to you along with GNU Emacs so you
                     17: ;; can know your rights and responsibilities.  It should be in a
                     18: ;; file named COPYING.  Among other things, the copyright notice
                     19: ;; and this notice must be preserved on all copies.
                     20: 
                     21: 
                     22: (defun compare-windows ()
                     23:   "Compare text in current window with text in next window.
                     24: Compares the text starting at point in each window,
                     25: moving over text in each one as far as they match."
                     26:   (interactive)
                     27:   (let (p1 p2 np1 np2 maxp1 maxp2 b1 b2 w2
                     28:           success size
                     29:           (opoint (point)))
                     30:     (setq p1 (point) b1 (current-buffer))
                     31:     (setq w2 (next-window (selected-window)))
                     32:     (if (eq w2 (selected-window))
                     33:        (error "No other window."))
                     34:     (setq p2 (window-point w2)
                     35:          b2 (window-buffer w2))
                     36:     (setq maxp1 (point-max))
                     37:     (save-excursion
                     38:      (set-buffer b2)
                     39:      (setq maxp2 (point-max)))
                     40: 
                     41:     (setq losep1 (+ 10 maxp1) losep2 (+ 10 maxp2))
                     42: 
                     43:     ;; Try advancing comparing 1000 chars at a time.
                     44:     ;; When that fails, go 500 chars at a time, and so on.
                     45:     (setq size 1000)
                     46:     (while (> size 0)
                     47:       (setq success t)
                     48:       (while success
                     49:        (setq np2 (min (+ p2 size) maxp2))
                     50:        (setq np1 (min (+ p1 size) maxp1))
                     51:        (save-excursion
                     52:         (set-buffer b2)
                     53:         (setq s2 (buffer-substring p2 np2)))
                     54:        (setq s1 (buffer-substring p1 np1))
                     55:        (setq success (and (/= np1 p1) (equal s1 s2)))
                     56:        ;; Don't bother retrying the last fraction of what already lost.
                     57:        (and success
                     58:             (or (> (+ p2 size) (- losep2 3))
                     59:                 (> (+ p1 size) (- losep1 3)))
                     60:             (> size 1)
                     61:             (setq success nil))
                     62:        (if success
                     63:            (setq p1 np1 p2 np2)
                     64:          (setq losep1 np1 losep2 np2
                     65:                maxp1 np1 maxp2 np2)))
                     66:       (setq size (min (- maxp1 p1) (- maxp2 p2) (/ size 2))))
                     67: 
                     68:     (goto-char p1)
                     69:     (set-window-point w2 p2)
                     70:     (if (= (point) opoint)
                     71:        (ding))))

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