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c0274f38 ER |
1 | ;;; compare-w.el --- compare text between windows for Emacs. |
2 | ||
048ab7d3 | 3 | ;; Copyright (C) 1986, 1989, 1993 Free Software Foundation, Inc. |
745bc783 | 4 | |
9750e079 ER |
5 | ;; Maintainer: FSF |
6 | ||
745bc783 JB |
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) |
745bc783 JB |
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 | ||
e41b2db1 ER |
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 | ||
048ab7d3 RS |
32 | (defvar compare-windows-whitespace "[ \t\n]+" |
33 | "*Regexp that defines whitespace sequences for \\[compare-windows]. | |
745bc783 JB |
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 | |
048ab7d3 | 64 | compare-windows-whitespace))) |
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65 | (setq p1 (point) b1 (current-buffer)) |
66 | (setq w2 (next-window (selected-window))) | |
67 | (if (eq w2 (selected-window)) | |
68 | (error "No other window")) | |
69 | (setq p2 (window-point w2) | |
70 | b2 (window-buffer w2)) | |
71 | (setq opoint2 p2) | |
72 | (setq maxp1 (point-max)) | |
73 | (save-excursion | |
74 | (set-buffer b2) | |
75 | (setq maxp2 (point-max))) | |
76 | ||
77 | (setq success t) | |
78 | (while success | |
79 | (setq success nil) | |
80 | ;; if interrupted, show how far we've gotten | |
81 | (goto-char p1) | |
82 | (set-window-point w2 p2) | |
83 | ||
84 | ;; If both buffers have whitespace next to point, | |
85 | ;; optionally skip over it. | |
86 | ||
87 | (and skip-whitespace | |
88 | (save-excursion | |
89 | (let (p1a p2a w1 w2 result1 result2) | |
048ab7d3 RS |
90 | (setq result1 |
91 | (if (stringp skip-whitespace) | |
92 | (compare-windows-skip-whitespace opoint1) | |
93 | (funcall skip-whitespace opoint1))) | |
94 | (setq p1a (point)) | |
745bc783 JB |
95 | (set-buffer b2) |
96 | (goto-char p2) | |
048ab7d3 RS |
97 | (setq result2 |
98 | (if (stringp skip-whitespace) | |
99 | (compare-windows-skip-whitespace opoint2) | |
100 | (funcall skip-whitespace opoint2))) | |
101 | (setq p2a (point)) | |
5a534851 RS |
102 | (if (or (stringp skip-whitespace) |
103 | (and result1 result2 (eq result1 result2))) | |
104 | (setq p1 p1a | |
105 | p2 p2a))))) | |
745bc783 JB |
106 | |
107 | ;; Try advancing comparing 1000 chars at a time. | |
108 | ;; When that fails, go 500 chars at a time, and so on. | |
109 | (let ((size 1000) | |
d76bfaa2 RS |
110 | success-1 |
111 | (case-fold-search compare-ignore-case)) | |
745bc783 JB |
112 | (while (> size 0) |
113 | (setq success-1 t) | |
d76bfaa2 | 114 | ;; Try comparing SIZE chars at a time, repeatedly, till that fails. |
745bc783 JB |
115 | (while success-1 |
116 | (setq size (min size (- maxp1 p1) (- maxp2 p2))) | |
745bc783 JB |
117 | (setq success-1 |
118 | (and (> size 0) | |
d76bfaa2 RS |
119 | (= 0 (compare-buffer-substrings b2 p2 (+ size p2) |
120 | b1 p1 (+ size p1))))) | |
745bc783 JB |
121 | (if success-1 |
122 | (setq p1 (+ p1 size) p2 (+ p2 size) | |
123 | success t))) | |
d76bfaa2 | 124 | ;; If SIZE chars don't match, try fewer. |
745bc783 JB |
125 | (setq size (/ size 2))))) |
126 | ||
127 | (goto-char p1) | |
128 | (set-window-point w2 p2) | |
129 | (if (= (point) opoint1) | |
130 | (ding)))) | |
49116ac0 | 131 | |
048ab7d3 RS |
132 | ;; Move forward over whatever might be called whitespace. |
133 | ;; compare-windows-whitespace is a regexp that matches whitespace. | |
134 | ;; Match it at various starting points before the original point | |
135 | ;; and find the latest point at which a match ends. | |
136 | ;; Don't try starting points before START, though. | |
137 | ;; Value is non-nil if whitespace is found. | |
7f5d3541 RS |
138 | |
139 | ;; If there is whitespace before point, but none after, | |
140 | ;; then return t, but don't advance point. | |
048ab7d3 RS |
141 | (defun compare-windows-skip-whitespace (start) |
142 | (let ((end (point)) | |
7f5d3541 | 143 | (beg (point)) |
048ab7d3 | 144 | (opoint (point))) |
5dd1ad8e | 145 | (while (or (and (looking-at compare-windows-whitespace) |
7f5d3541 RS |
146 | (<= end (match-end 0)) |
147 | ;; This match goes past END, so advance END. | |
148 | (progn (setq end (match-end 0)) | |
5dd1ad8e RS |
149 | (> (point) start))) |
150 | (and (/= (point) start) | |
151 | ;; Consider at least the char before point, | |
152 | ;; unless it is also before START. | |
153 | (= (point) opoint))) | |
048ab7d3 RS |
154 | ;; keep going back until whitespace |
155 | ;; doesn't extend to or past end | |
156 | (forward-char -1)) | |
7f5d3541 | 157 | (setq beg (point)) |
048ab7d3 | 158 | (goto-char end) |
7f5d3541 RS |
159 | (or (/= beg opoint) |
160 | (/= end opoint)))) | |
048ab7d3 | 161 | |
49116ac0 JB |
162 | (provide 'compare-w) |
163 | ||
c0274f38 | 164 | ;;; compare-w.el ends here |