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1 ;;; compare-w.el --- compare text between windows for Emacs
3 ;; Copyright (C) 1986, 1989, 1993, 1997, 2001-2011
4 ;; Free Software Foundation, Inc.
6 ;; Maintainer: FSF
7 ;; Keywords: convenience files vc
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 3 of the License, or
14 ;; (at your option) 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. If not, see <http://www.gnu.org/licenses/>.
24 ;;; Commentary:
26 ;; This package provides one entry point, compare-windows. It compares
27 ;; text starting from point in two adjacent windows, advancing point
28 ;; until it finds a difference. Option variables permit you to ignore
29 ;; whitespace differences, or case differences, or both.
31 ;;; Code:
34 "Compare text between windows."
39 "Regexp or function that defines whitespace sequences for `compare-windows'.
40 That command optionally ignores changes in whitespace.
42 The value of `compare-windows-whitespace' is normally a regexp, but it
43 can also be a function. The function's job is to categorize any
44 whitespace around (including before) point; it should also advance
45 past any whitespace. The function is called in each window, with
46 point at the current scanning point. It gets one argument, the point
48 any text before that point.
50 If the function returns the same value for both windows, then the
51 whitespace is considered to match, and is skipped."
56 "Non-nil means `compare-windows' ignores whitespace."
62 "Non-nil means `compare-windows' ignores case differences."
67 "Function or regexp that is used to synchronize points in two
68 windows if before calling `compare-windows' points are located
69 on mismatched positions.
71 The value of `compare-windows-sync' can be a function. The
72 function's job is to advance points in both windows to the next
73 matching text. If the value of `compare-windows-sync' is a
74 regexp, then points in both windows are advanced to the next
75 occurrence of this regexp.
77 The current default value is the general function
78 `compare-windows-sync-default-function' that is able to
79 synchronize points by using quadratic algorithm to find the first
80 matching 32-character string in two windows.
82 The other useful values of this variable could be such functions
83 as `forward-word', `forward-sentence', `forward-paragraph', or a
84 regexp containing some field separator or a newline, depending on
85 the nature of the difference units separator. The variable can
86 be made buffer-local.
89 no synchronization is performed, and the function `ding' is called
90 to beep or flash the screen when points are mismatched."
96 "Size of string from one window that is searched in second window.
98 Small number makes difference regions more fine-grained, but it
99 may fail by finding the wrong match. The bigger number makes
100 difference regions more coarse-grained.
102 The default value 32 is good for the most cases."
108 "List of two values, each of which is used as argument of
109 function `recenter' called in each of two windows to place
110 matching points side-by-side.
112 The value `(-1 0)' is useful if windows are split vertically,
113 and the value `((4) (4))' for horizontally split windows."
119 "Non-nil means compare-windows highlights the differences.
120 The value t removes highlighting immediately after invoking a command
121 other than `compare-windows'.
122 The value `persistent' leaves all highlighted differences. You can clear
123 out all highlighting later with the command `compare-windows-dehighlight'."
132 "Face for highlighting of compare-windows difference regions."
142 ;;;###autoload
144 "Compare text in current window with text in next window.
145 Compares the text starting at point in each window,
146 moving over text in each one as far as they match.
148 This command pushes the mark in each window
149 at the prior location of point in that window.
150 If both windows display the same buffer,
151 the mark is pushed twice in that buffer:
152 first in the other window, then in the selected window.
154 A prefix arg means reverse the value of variable
155 `compare-ignore-whitespace'. If `compare-ignore-whitespace' is
156 nil, then a prefix arg means ignore changes in whitespace. If
157 `compare-ignore-whitespace' is non-nil, then a prefix arg means
158 don't ignore changes in whitespace. The variable
159 `compare-windows-whitespace' controls how whitespace is skipped.
160 If `compare-ignore-case' is non-nil, changes in case are also
161 ignored.
163 If `compare-windows-sync' is non-nil, then successive calls of
164 this command work in interlaced mode:
165 on first call it advances points to the next difference,
166 on second call it synchronizes points by skipping the difference,
167 on third call it again advances points to the next difference and so on."
174 opoint2
175 skip-func-1
176 skip-func-2
178 'compare-windows-sync-regexp
179 compare-windows-sync)))
195 t)
196 compare-windows-whitespace)))
203 t)
204 compare-windows-whitespace)))
210 ;; If both windows have whitespace next to point,
211 ;; optionally skip over it.
223 p2 p2a)))))
231 ;; Advance point now rather than later, in case we're interrupted.
241 ;; If points are not advanced (i.e. already on mismatch position),
242 ;; then synchronize points between both windows
256 ;; If points are still not synchronized, then ding
258 ;; Display error message when current points in two windows
259 ;; are unmatched and next matching points can't be found.
264 ;; Move forward over whatever might be called whitespace.
265 ;; compare-windows-whitespace is a regexp that matches whitespace.
266 ;; Match it at various starting points before the original point
267 ;; and find the latest point at which a match ends.
268 ;; Don't try starting points before START, though.
269 ;; Value is non-nil if whitespace is found.
270 ;; If there is whitespace before point, but none after,
271 ;; then return t, but don't advance point.
278 ;; This match goes past END, so advance END.
282 ;; Consider at least the char before point,
283 ;; unless it is also before START.
285 ;; keep going back until whitespace
286 ;; doesn't extend to or past end
293 ;; Move forward to the next synchronization regexp.
298 ;; Function works in two passes: one call on each window.
299 ;; On the first call both matching points are computed,
300 ;; and one of them is stored in compare-windows-sync-point
301 ;; to be used when this function is called on second window.
312 in-bounds-p s1 p2 p12s p12)
314 ;; until matching points are found
316 ;; until size exceeds the maximum points of both buffers
317 ;; (bounds below take care to not overdo in each of them)
320 ;; until string size becomes smaller than 4
323 ;; make the next search in the double-sized region;
324 ;; on first iteration it is 2*compare-windows-sync-string-size,
325 ;; on last iterations it exceeds both buffers maximum points
327 ;; if region size exceeds the maximum points of both buffers,
328 ;; then start to halve the string size until 4;
329 ;; this helps to find differences near the end of buffers
345 ;; use closest matching points (i.e. points with minimal sum)
351 ;; else set point in the second window to the pre-calculated value
356 ;; Highlight differences
372 ;; Remove highlighting before next command is executed
382 "Remove highlighting created by `compare-windows-highlight'."
392 ;;; compare-w.el ends here