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1 ;;; compare-w.el --- compare text between windows for Emacs
3 ;; Copyright (C) 1986, 1989, 1993, 1997, 2001-2014 Free Software
4 ;; 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."
57 "Non-nil means command `compare-windows' ignores whitespace."
63 "Non-nil means command `compare-windows' ignores case differences."
68 "Function or regexp that is used to synchronize points in two
69 windows if before calling `compare-windows' points are located
70 on mismatched positions.
72 The value of `compare-windows-sync' can be a function. The
73 function's job is to advance points in both windows to the next
74 matching text. If the value of `compare-windows-sync' is a
75 regexp, then points in both windows are advanced to the next
76 occurrence of this regexp.
78 The current default value is the general function
79 `compare-windows-sync-default-function' that is able to
80 synchronize points by using quadratic algorithm to find the first
81 matching 32-character string in two windows.
83 The other useful values of this variable could be such functions
84 as `forward-word', `forward-sentence', `forward-paragraph', or a
85 regexp containing some field separator or a newline, depending on
86 the nature of the difference units separator. The variable can
87 be made buffer-local.
90 no synchronization is performed, and the function `ding' is called
91 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.
121 The value t removes highlighting immediately after invoking a command
122 other than `compare-windows'.
123 The value `persistent' leaves all highlighted differences. You can clear
124 out all highlighting later with the command `compare-windows-dehighlight'."
133 "Face for highlighting of compare-windows difference regions."
143 ;;;###autoload
145 "Compare text in current window with text in next window.
146 Compares the text starting at point in each window,
147 moving over text in each one as far as they match.
149 This command pushes the mark in each window
150 at the prior location of point in that window.
151 If both windows display the same buffer,
152 the mark is pushed twice in that buffer:
153 first in the other window, then in the selected window.
155 A prefix arg means reverse the value of variable
156 `compare-ignore-whitespace'. If `compare-ignore-whitespace' is
157 nil, then a prefix arg means ignore changes in whitespace. If
158 `compare-ignore-whitespace' is non-nil, then a prefix arg means
159 don't ignore changes in whitespace. The variable
160 `compare-windows-whitespace' controls how whitespace is skipped.
161 If `compare-ignore-case' is non-nil, changes in case are also
162 ignored.
164 If `compare-windows-sync' is non-nil, then successive calls of
165 this command work in interlaced mode:
166 on first call it advances points to the next difference,
167 on second call it synchronizes points by skipping the difference,
168 on third call it again advances points to the next difference and so on."
175 opoint2
176 skip-func-1
177 skip-func-2
179 'compare-windows-sync-regexp
180 compare-windows-sync)))
196 t)
197 compare-windows-whitespace)))
204 t)
205 compare-windows-whitespace)))
211 ;; If both windows have whitespace next to point,
212 ;; optionally skip over it.
224 p2 p2a)))))
232 ;; Advance point now rather than later, in case we're interrupted.
242 ;; If points are not advanced (i.e. already on mismatch position),
243 ;; then synchronize points between both windows
257 ;; If points are still not synchronized, then ding
259 ;; Display error message when current points in two windows
260 ;; are unmatched and next matching points can't be found.
265 ;; Move forward over whatever might be called whitespace.
266 ;; compare-windows-whitespace is a regexp that matches whitespace.
267 ;; Match it at various starting points before the original point
268 ;; and find the latest point at which a match ends.
269 ;; Don't try starting points before START, though.
270 ;; Value is non-nil if whitespace is found.
271 ;; If there is whitespace before point, but none after,
272 ;; then return t, but don't advance point.
279 ;; This match goes past END, so advance END.
283 ;; Consider at least the char before point,
284 ;; unless it is also before START.
286 ;; keep going back until whitespace
287 ;; doesn't extend to or past end
294 ;; Move forward to the next synchronization regexp.
299 ;; Function works in two passes: one call on each window.
300 ;; On the first call both matching points are computed,
301 ;; and one of them is stored in compare-windows-sync-point
302 ;; to be used when this function is called on second window.
313 in-bounds-p s1 p2 p12s p12)
315 ;; until matching points are found
317 ;; until size exceeds the maximum points of both buffers
318 ;; (bounds below take care to not overdo in each of them)
321 ;; until string size becomes smaller than 4
324 ;; make the next search in the double-sized region;
325 ;; on first iteration it is 2*compare-windows-sync-string-size,
326 ;; on last iterations it exceeds both buffers maximum points
328 ;; if region size exceeds the maximum points of both buffers,
329 ;; then start to halve the string size until 4;
330 ;; this helps to find differences near the end of buffers
346 ;; use closest matching points (i.e. points with minimal sum)
352 ;; else set point in the second window to the pre-calculated value
357 ;; Highlight differences
373 ;; Remove highlighting before next command is executed
383 "Remove highlighting created by function `compare-windows-highlight'."
393 ;;; compare-w.el ends here