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1 ;;; compare-w.el --- compare text between windows for Emacs
3 ;; Copyright (C) 1986, 1989, 1993, 1997, 2002, 2003, 2004,
4 ;; 2005, 2006 Free Software Foundation, Inc.
6 ;; Maintainer: FSF
7 ;; Keywords: convenience files
9 ;; This file is part of GNU Emacs.
11 ;; GNU Emacs is free software; you can redistribute it and/or modify
12 ;; it under the terms of the GNU General Public License as published by
13 ;; the Free Software Foundation; either version 2, or (at your option)
14 ;; any later version.
16 ;; GNU Emacs is distributed in the hope that it will be useful,
17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 ;; GNU General Public License for more details.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with GNU Emacs; see the file COPYING. If not, write to the
23 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
24 ;; Boston, MA 02110-1301, USA.
26 ;;; Commentary:
28 ;; This package provides one entry point, compare-windows. It compares
29 ;; text starting from point in two adjacent windows, advancing point
30 ;; until it finds a difference. Option variables permit you to ignore
31 ;; whitespace differences, or case differences, or both.
33 ;;; Code:
36 "Compare text between windows."
41 "*Regexp or function that defines whitespace sequences for `compare-windows'.
42 That command optionally ignores changes in whitespace.
44 The value of `compare-windows-whitespace' is normally a regexp, but it
45 can also be a function. The function's job is to categorize any
46 whitespace around (including before) point; it should also advance
47 past any whitespace. The function is called in each window, with
48 point at the current scanning point. It gets one argument, the point
50 any text before that point.
52 If the function returns the same value for both windows, then the
53 whitespace is considered to match, and is skipped."
58 "*Non-nil means `compare-windows' ignores whitespace."
64 "*Non-nil means `compare-windows' ignores case differences."
69 "*Function or regexp that is used to synchronize points in two
70 windows if before calling `compare-windows' points are located
71 on mismatched positions.
73 The value of `compare-windows-sync' can be a function. The
74 function's job is to advance points in both windows to the next
75 matching text. If the value of `compare-windows-sync' is a
76 regexp, then points in both windows are advanced to the next
77 occurrence of this regexp.
79 The current default value is the general function
80 `compare-windows-sync-default-function' that is able to
81 synchronize points by using quadratic algorithm to find the first
82 matching 32-character string in two windows.
84 The other useful values of this variable could be such functions
85 as `forward-word', `forward-sentence', `forward-paragraph', or a
86 regexp containing some field separator or a newline, depending on
87 the nature of the difference units separator. The variable can
88 be made buffer-local.
90 If the value of this variable is `nil', then function `ding' is
91 called to beep or flash the screen when points are mismatched."
97 "*Size of string from one window that is searched in second window.
99 Small number makes difference regions more fine-grained, but it
100 may fail by finding the wrong match. The bigger number makes
101 difference regions more coarse-grained.
103 The default value 32 is good for the most cases."
109 "*List of two values, each of which is used as argument of
110 function `recenter' called in each of two windows to place
111 matching points side-by-side.
113 The value `(-1 0)' is useful if windows are split vertically,
114 and the value `((4) (4))' for horizontally split windows."
120 "*Non-nil means compare-windows highlights the differences."
127 "Face for highlighting of compare-windows difference regions."
135 ;;;###autoload
137 "Compare text in current window with text in next window.
138 Compares the text starting at point in each window,
139 moving over text in each one as far as they match.
141 This command pushes the mark in each window
142 at the prior location of point in that window.
143 If both windows display the same buffer,
144 the mark is pushed twice in that buffer:
145 first in the other window, then in the selected window.
147 A prefix arg means reverse the value of variable
148 `compare-ignore-whitespace'. If `compare-ignore-whitespace' is
149 nil, then a prefix arg means ignore changes in whitespace. If
150 `compare-ignore-whitespace' is non-nil, then a prefix arg means
151 don't ignore changes in whitespace. The variable
152 `compare-windows-whitespace' controls how whitespace is skipped.
153 If `compare-ignore-case' is non-nil, changes in case are also
154 ignored.
156 If `compare-windows-sync' is non-nil, then successive calls of
157 this command work in interlaced mode:
158 on first call it advances points to the next difference,
159 on second call it synchronizes points by skipping the difference,
160 on third call it again advances points to the next difference and so on."
165 opoint2
168 compare-ignore-whitespace)
170 'compare-windows-skip-whitespace
171 compare-windows-whitespace)))
173 'compare-windows-sync-regexp
174 compare-windows-sync)))
192 ;; If both windows have whitespace next to point,
193 ;; optionally skip over it.
206 p2 p2a)))))
214 ;; Advance point now rather than later, in case we're interrupted.
224 ;; If points are not advanced (i.e. already on mismatch position),
225 ;; then synchronize points between both windows
239 ;; If points are still not synchronized, then ding
241 ;; Display error message when current points in two windows
242 ;; are unmatched and next matching points can't be found.
247 ;; Move forward over whatever might be called whitespace.
248 ;; compare-windows-whitespace is a regexp that matches whitespace.
249 ;; Match it at various starting points before the original point
250 ;; and find the latest point at which a match ends.
251 ;; Don't try starting points before START, though.
252 ;; Value is non-nil if whitespace is found.
253 ;; If there is whitespace before point, but none after,
254 ;; then return t, but don't advance point.
261 ;; This match goes past END, so advance END.
265 ;; Consider at least the char before point,
266 ;; unless it is also before START.
268 ;; keep going back until whitespace
269 ;; doesn't extend to or past end
276 ;; Move forward to the next synchronization regexp.
281 ;; Function works in two passes: one call on each window.
282 ;; On the first call both matching points are computed,
283 ;; and one of them is stored in compare-windows-sync-point
284 ;; to be used when this function is called on second window.
295 in-bounds-p s1 p2 p12s p12)
297 ;; until matching points are found
299 ;; until size exceeds the maximum points of both buffers
300 ;; (bounds below take care to not overdo in each of them)
303 ;; until string size becomes smaller than 4
306 ;; make the next search in the double-sized region;
307 ;; on first iteration it is 2*compare-windows-sync-string-size,
308 ;; on last iterations it exceeds both buffers maximum points
310 ;; if region size exceeds the maximum points of both buffers,
311 ;; then start to halve the string size until 4;
312 ;; this helps to find differences near the end of buffers
328 ;; use closest matching points (i.e. points with minimal sum)
334 ;; else set point in the second window to the pre-calculated value
339 ;; Highlight differences
354 ;; Remove highlighting before next command is executed
358 "Remove highlighting created by `compare-windows-highlight'."
366 ;;; arch-tag: 4177aab1-48e6-4a98-b7a1-000ee285de46
367 ;;; compare-w.el ends here