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1 | ;;; compare-w.el --- compare text between windows for Emacs. |
2 | ||
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3 | ;; Copyright (C) 1986, 1989 Free Software Foundation, Inc. |
4 | ||
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5 | ;; Maintainer: FSF |
6 | ||
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7 | ;; This file is part of GNU Emacs. |
8 | ||
9 | ;; GNU Emacs is free software; you can redistribute it and/or modify | |
10 | ;; it under the terms of the GNU General Public License as published by | |
e5167999 | 11 | ;; the Free Software Foundation; either version 2, or (at your option) |
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12 | ;; any later version. |
13 | ||
14 | ;; GNU Emacs is distributed in the hope that it will be useful, | |
15 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
17 | ;; GNU General Public License for more details. | |
18 | ||
19 | ;; You should have received a copy of the GNU General Public License | |
20 | ;; along with GNU Emacs; see the file COPYING. If not, write to | |
21 | ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. | |
22 | ||
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23 | ;;; Commentary: |
24 | ||
25 | ;; This package provides one entry point, compare-windows. It compares | |
26 | ;; text starting from point in two adjacent windows, advancing point | |
27 | ;; until it finds a difference. Option variables permit you to ignore | |
28 | ;; whitespace differences, or case differences, or both. | |
29 | ||
e5167999 ER |
30 | ;;; Code: |
31 | ||
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32 | (defvar compare-windows-whitespace " \t\n" |
33 | "*String of characters considered whitespace for \\[compare-windows]. | |
34 | Changes in whitespace are optionally ignored. | |
35 | ||
36 | The value of `compare-windows-whitespace' may instead be a function; this | |
37 | function is called in each buffer, with point at the current scanning point. | |
38 | The function's job is to categorize any whitespace around (including before) | |
39 | point; it should also advance past any whitespace. | |
40 | ||
41 | The function is passed one argument, the point where `compare-windows' | |
42 | was originally called; it should not consider any text before that point. | |
43 | If the function returns the same value for both buffers, then the | |
44 | whitespace is considered to match, and is skipped.") | |
45 | ||
46 | (defvar compare-ignore-case nil | |
47 | "*Non-nil means \\[compare-windows] ignores case differences.") | |
48 | ||
49 | ;;;###autoload | |
50 | (defun compare-windows (ignore-whitespace) | |
51 | "Compare text in current window with text in next window. | |
52 | Compares the text starting at point in each window, | |
53 | moving over text in each one as far as they match. | |
54 | ||
55 | A prefix arg means ignore changes in whitespace. | |
56 | The variable `compare-windows-whitespace' controls how whitespace is skipped. | |
57 | If `compare-ignore-case' is non-nil, changes in case are also ignored." | |
58 | (interactive "P") | |
59 | (let* (p1 p2 maxp1 maxp2 b1 b2 w2 | |
60 | success size | |
61 | (opoint1 (point)) | |
62 | opoint2 | |
63 | (skip-whitespace (if ignore-whitespace | |
64 | compare-windows-whitespace)) | |
65 | (skip-whitespace-regexp (concat "[" skip-whitespace "]+"))) | |
66 | (setq p1 (point) b1 (current-buffer)) | |
67 | (setq w2 (next-window (selected-window))) | |
68 | (if (eq w2 (selected-window)) | |
69 | (error "No other window")) | |
70 | (setq p2 (window-point w2) | |
71 | b2 (window-buffer w2)) | |
72 | (setq opoint2 p2) | |
73 | (setq maxp1 (point-max)) | |
74 | (save-excursion | |
75 | (set-buffer b2) | |
76 | (setq maxp2 (point-max))) | |
77 | ||
78 | (setq success t) | |
79 | (while success | |
80 | (setq success nil) | |
81 | ;; if interrupted, show how far we've gotten | |
82 | (goto-char p1) | |
83 | (set-window-point w2 p2) | |
84 | ||
85 | ;; If both buffers have whitespace next to point, | |
86 | ;; optionally skip over it. | |
87 | ||
88 | (and skip-whitespace | |
89 | (save-excursion | |
90 | (let (p1a p2a w1 w2 result1 result2) | |
91 | (if (stringp skip-whitespace) | |
92 | (progn | |
93 | (if (not (eobp)) | |
94 | (skip-chars-backward skip-whitespace opoint1)) | |
95 | (and (looking-at skip-whitespace-regexp) | |
96 | (setq p1a (match-end 0) result1 t))) | |
97 | (setq result1 (funcall skip-whitespace opoint1)) | |
98 | (setq p1a (point))) | |
99 | (set-buffer b2) | |
100 | (goto-char p2) | |
101 | (if (stringp skip-whitespace) | |
102 | (progn | |
103 | (if (not (eobp)) | |
104 | (skip-chars-backward skip-whitespace opoint2)) | |
105 | (and (looking-at skip-whitespace-regexp) | |
106 | (setq p2a (match-end 0) result2 t))) | |
107 | (setq result2 (funcall skip-whitespace opoint2)) | |
108 | (setq p2a (point))) | |
109 | (and result1 result2 (eq result1 result2) | |
110 | (setq p1 p1a | |
111 | p2 p2a))))) | |
112 | ||
113 | ;; Try advancing comparing 1000 chars at a time. | |
114 | ;; When that fails, go 500 chars at a time, and so on. | |
115 | (let ((size 1000) | |
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116 | success-1 |
117 | (case-fold-search compare-ignore-case)) | |
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118 | (while (> size 0) |
119 | (setq success-1 t) | |
d76bfaa2 | 120 | ;; Try comparing SIZE chars at a time, repeatedly, till that fails. |
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121 | (while success-1 |
122 | (setq size (min size (- maxp1 p1) (- maxp2 p2))) | |
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123 | (setq success-1 |
124 | (and (> size 0) | |
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125 | (= 0 (compare-buffer-substrings b2 p2 (+ size p2) |
126 | b1 p1 (+ size p1))))) | |
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127 | (if success-1 |
128 | (setq p1 (+ p1 size) p2 (+ p2 size) | |
129 | success t))) | |
d76bfaa2 | 130 | ;; If SIZE chars don't match, try fewer. |
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131 | (setq size (/ size 2))))) |
132 | ||
133 | (goto-char p1) | |
134 | (set-window-point w2 p2) | |
135 | (if (= (point) opoint1) | |
136 | (ding)))) | |
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137 | |
138 | (provide 'compare-w) | |
139 | ||
c0274f38 | 140 | ;;; compare-w.el ends here |