summaryrefslogtreecommitdiff
path: root/lisp/hilit-chg.el
blob: 0f84a0406af8623d74533b7118c8c55f9c44a2dd (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
;;; hilit-chg.el --- minor mode displaying buffer changes with special face

;; Copyright (C) 1998, 2000, 2001, 2002, 2003, 2004,
;;   2005, 2006, 2007, 2008 Free Software Foundation, Inc.

;; Author: Richard Sharman <rsharman@pobox.com>
;; Keywords: faces

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; A minor mode: "Highlight Changes mode".

;; When Highlight Changes mode is enabled changes to the buffer are
;; recorded with a text property.  Normally these ranges of text are
;; displayed in a distinctive face.  However, sometimes it is
;; desirable to temporarily not see these changes.  Instead of
;; disabling Highlight Changes mode (which would remove the text property)
;; use the command highlight-changes-visible-mode.

;; Two faces are supported: one for changed or inserted text and
;; another for the first character after text has been deleted.

;; When Highlight Changes mode is on (even if changes are not visible)
;; you can go to the next or previous change with
;; `highlight-changes-next-change' or `highlight-changes-previous-change'.

;; Command highlight-compare-with-file shows changes in this file
;; compared with another file (by default the previous version of the
;; file).
;;
;; The command highlight-compare-buffers compares two buffers by
;; highlighting their differences.

;; You can "age" different sets of changes by using
;; `highlight-changes-rotate-faces'.  This rotates through a series
;; of different faces, so you can distinguish "new" changes from "older"
;; changes.  You can customize these "rotated" faces in two ways.  You can
;; either explicitly define each face by customizing
;; `highlight-changes-face-list'.  If, however, the faces differ from
;; `highlight-changes-face' only in the foreground color, you can simply set
;; `highlight-changes-colors'.  If `highlight-changes-face-list' is nil when
;; the faces are required they will be constructed from
;; `highlight-changes-colors'.

;; You can automatically rotate faces when the buffer is saved;
;; see function `highlight-changes-rotate-faces' for how to do this.

;; The hook `highlight-changes-mode-hook' is called when
;; Highlight Changes mode is turned on or off.
;; When it called, variable `highlight-changes-mode' has been updated
;; to the new value.
;;
;; Example usage:
;; (defun my-highlight-changes-mode-hook ()
;;   (if highlight-changes-mode
;;       (add-hook 'write-file-functions 'highlight-changes-rotate-faces nil t)
;;     (remove-hook 'write-file-functions 'highlight-changes-rotate-faces t)
;;     ))


;;           Automatically enabling Highlight Changes mode
;;

;; Normally, Highlight Changes mode is turned on explicitly in a buffer.
;;
;; If you prefer to have it automatically invoked you can do it as
;; follows.

;; 1. Most modes have a major-hook, typically called MODE-hook.  You
;; can use `add-hook' to call `highlight-changes-mode'.

;;   Example:
;;	(add-hook 'c-mode-hook 'highlight-changes-mode)

;; However, this cannot be done for Fundamental mode for there is no
;; such hook.

;; 2. You can use the function `global-highlight-changes-mode'
;;
;; This function, which is fashioned after the way `global-font-lock' works,
;; toggles on or off global Highlight Changes mode.  When activated, it turns
;; on Highlight Changes mode in all "suitable" existing buffers and will turn
;; it on in new "suitable" buffers to be created.

;; A buffer's "suitability" is determined by variable
;; `highlight-changes-global-modes', as follows.  If it is
;; * nil  -- then no buffers are suitable;
;; * a function -- this function is called and the result is used.  As
;;   an example, if the value is `buffer-file-name' then all buffers
;;   who are visiting files are suitable, but others (like dired
;;   buffers) are not;
;; * a list -- then the buffer is suitable if and only if its mode is in the
;;   list, except if the first element is `not', in which case the test
;;   is reversed (i.e. it is a list of unsuitable modes).
;; * Otherwise, the buffer is suitable if its name does not begin with
;;   ` ' or `*' and if `buffer-file-name' returns true.

;; To enable it for future sessions put this in your ~/.emacs file:
;;		(global-highlight-changes-mode t)


;;     Possible bindings:
;; (global-set-key '[C-right] 'highlight-changes-next-change)
;; (global-set-key '[C-left]  'highlight-changes-previous-change)
;;
;;     Other interactive functions (that could be bound if desired):
;; highlight-changes-mode
;; highlight-changes-toggle-visibility
;; highlight-changes-remove-highlight
;; highlight-compare-with-file
;; highlight-compare-buffers
;; highlight-changes-rotate-faces


;;; Bugs:

;; - the next-change and previous-change functions are too literal;
;;   they should find the next "real" change, in other words treat
;;   consecutive changes as one.


;;; To do (maybe), notes, ...

;; - having different faces for deletion and non-deletion: is it
;;   really worth the hassle?
;; - highlight-compare-with-file should allow RCS files - e.g. nice to be
;;   able to say show changes compared with version 2.1.


;;; History:

;; R Sharman (rsharman@pobox.com) Feb 1998:
;; - initial release as change-mode.
;; Jari Aalto <jari.aalto@ntc.nokia.com> Mar 1998
;; - fixes for byte compile errors
;; - use eval-and-compile for autoload
;; Marijn Ros <J.M.Ros@fys.ruu.nl> Mar 98
;; - suggested turning it on by default
;; Eric Ludlam <zappo@gnu.org> Suggested using overlays.
;; July 98
;; - global mode and various stuff added
;; - Changed to use overlays
;; August 98
;; - renamed to Highlight Changes mode.
;; Dec 2003
;; - Use require for ediff stuff
;; - Added highlight-compare-buffers
;; Mar 2008
;; - Made highlight-changes-mode like other modes (toggle on/off)
;; - Added new command highlight-changes-visible-mode to replace the
;;   previous active/passive aspect of highlight-changes-mode.
;; - Removed highlight-changes-toggle-hook
;; - Put back eval-and-compile inadvertently dropped
;; May 2008
;; - Removed highlight-changes-disable-hook and highlight-changes-enable-hook
;;   because highlight-changes-mode-hook can do both.

;;; Code:

(require 'wid-edit)

;; ====================== Customization =======================
(defgroup highlight-changes nil
  "Highlight Changes mode."
  :version "20.4"
  :group 'faces)


;; Face information: How the changes appear.

;; Defaults for face: red foreground, no change to background,
;; and underlined if a change is because of a deletion.
;; Note: underlining is helpful in that it shows up changes in white space.
;; However, having it set for non-delete changes can be annoying because all
;; indentation on inserts gets underlined (which can look pretty ugly!).

(defface highlight-changes
  '((((min-colors 88) (class color)) (:foreground "red1"))
    (((class color)) (:foreground "red" ))
    (t (:inverse-video t)))
  "Face used for highlighting changes."
  :group 'highlight-changes)
;; backward-compatibility alias
(put 'highlight-changes-face 'face-alias 'highlight-changes)

;; This looks pretty ugly, actually.  Maybe the underline should be removed.
(defface highlight-changes-delete
  '((((min-colors 88) (class color)) (:foreground "red1" :underline t))
    (((class color)) (:foreground "red" :underline t))
    (t (:inverse-video t)))
  "Face used for highlighting deletions."
  :group 'highlight-changes)
;; backward-compatibility alias
(put 'highlight-changes-delete-face 'face-alias 'highlight-changes-delete)



;; A (not very good) default list of colors to rotate through.
;;
(define-obsolete-variable-alias 'highlight-changes-colours
                                'highlight-changes-colors "22.1")

(defcustom highlight-changes-colors
  (if (eq (frame-parameter nil 'background-mode) 'light)
      ;; defaults for light background:
      '( "magenta" "blue" "darkgreen" "chocolate" "sienna4" "NavyBlue")
      ;; defaults for dark background:
    '("yellow" "magenta" "blue" "maroon" "firebrick" "green4" "DarkOrchid"))
  "Colors used by `highlight-changes-rotate-faces'.
The newest rotated change will be displayed in the first element of this list,
the next older will be in the second element etc.

This list is used if `highlight-changes-face-list' is nil, otherwise that
variable overrides this list.  If you only care about foreground
colors then use this, if you want fancier faces then set
`highlight-changes-face-list'."
  :type '(repeat color)
  :group 'highlight-changes)

;; When you invoke highlight-changes-mode, should highlight-changes-visible-mode
;; be on or off?

(define-obsolete-variable-alias 'highlight-changes-initial-state
  'highlight-changes-visibility-initial-state "23.1")

(defcustom highlight-changes-visibility-initial-state t
  "Controls whether changes are initially visible in Highlight Changes mode.

This controls the initial value of `highlight-changes-visible-mode'.
When a buffer is in Highlight Changes mode the function
`highlight-changes-visible-mode' is used to toggle the mode on or off."
  :type 'boolean
  :group 'highlight-changes)

;; highlight-changes-global-initial-state has been removed



;; These are the strings displayed in the mode-line for the minor mode:
(define-obsolete-variable-alias 'highlight-changes-active-string
  'highlight-changes-visible-string "23.1")

(defcustom highlight-changes-visible-string " +Chg"
  "The string used when in Highlight Changes mode and changes are visible.
This should be set to nil if no indication is desired, or to
a string with a leading space."
  :type '(choice string
		 (const :tag "None"  nil))
  :group 'highlight-changes)

(define-obsolete-variable-alias 'highlight-changes-passive-string
  'highlight-changes-invisible-string "23.1")

(defcustom highlight-changes-invisible-string " -Chg"
  "The string used when in Highlight Changes mode and changes are hidden.
This should be set to nil if no indication is desired, or to
a string with a leading space."
  :type '(choice string
		 (const :tag "None"  nil))
  :group 'highlight-changes)

(defcustom highlight-changes-global-modes t
  "Determine whether a buffer is suitable for global Highlight Changes mode.

A function means call that function to decide: if it returns non-nil,
the buffer is suitable.

A list means the elements are major modes suitable for Highlight
Changes mode, or a list whose first element is `not' followed by major
modes which are not suitable.

A value of t means the buffer is suitable if it is visiting a file and
its name does not begin with ` ' or `*'.

A value of nil means no buffers are suitable for `global-highlight-changes-mode'
\(effectively disabling the mode).

Example:
	(c-mode c++-mode)
means that Highlight Changes mode is turned on for buffers in C and C++
modes only."
  :type '(choice
	  (const :tag "all non-special buffers visiting files" t)
	  (set :menu-tag "specific modes" :tag "modes"
	       :value (not)
	       (const :tag "All except these" not)
	       (repeat :tag "Modes" :inline t (symbol :tag "mode")))
	  (function :menu-tag "determined by function"
			   :value buffer-file-name)
	  (const :tag "none" nil)
	  )
  :group 'highlight-changes)

(defcustom highlight-changes-global-changes-existing-buffers nil
  "If non-nil, toggling global Highlight Changes mode affects existing buffers.
Normally, `global-highlight-changes' affects only new buffers (to be
created).  However, if `highlight-changes-global-changes-existing-buffers'
is non-nil, then turning on `global-highlight-changes' will turn on
Highlight Changes mode in suitable buffers, and turning the mode off will
remove it from existing buffers."
  :type 'boolean
  :group 'highlight-changes)

;; These are for internal use.

(defvar hilit-chg-list nil)
(defvar hilit-chg-string " ??")

(make-variable-buffer-local 'hilit-chg-string)



;;; Functions...

;;;###autoload
(define-minor-mode highlight-changes-mode
  "Toggle Highlight Changes mode.

With ARG, turn Highlight Changes mode on if and only if arg is positive.

In Highlight Changes mode changes are recorded with a text property.
Normally they are displayed in a distinctive face, but command
\\[highlight-changes-visible-mode] can be used to toggles this
on and off.

Other functions for buffers in this mode include:
\\[highlight-changes-next-change] - move point to beginning of next change
\\[highlight-changes-previous-change] - move to beginning of previous change
\\[highlight-changes-remove-highlight] - remove the change face from the region
\\[highlight-changes-rotate-faces] - rotate different \"ages\" of changes
through	various faces.
\\[highlight-compare-with-file] - mark text as changed by comparing this
buffer with the contents of a file
\\[highlight-compare-buffers] highlights differences between two buffers."
  nil			;; init-value
  hilit-chg-string	;; lighter
  nil			;; keymap
  (if (or (display-color-p)
	  (and (fboundp 'x-display-grayscale-p) (x-display-grayscale-p)))
      (progn
	(if (and (eq this-command 'global-highlight-changes-mode)
		 (not highlight-changes-global-changes-existing-buffers))
	    ;; The global mode has toggled the value of the mode variable,
	    ;; but not other changes have been mode, so we are safe
	    ;; to retoggle it.
	    (setq highlight-changes-mode (not highlight-changes-mode)))
	(if highlight-changes-mode
	    ;; it is being turned on
	    (hilit-chg-set)
	  ;; mode is turned off
	  (hilit-chg-clear)))
    (message "Highlight Changes mode requires color or grayscale display")))


;;;###autoload
(define-minor-mode highlight-changes-visible-mode
  "Toggle visiblility of changes when buffer is in Highlight Changes mode.

This mode only has an effect when Highlight Changes mode is on.
It allows toggling between whether or not the changed text is displayed
in a distinctive face.

The default value can be customized with variable
`highlight-changes-visibility-initial-state'

This command does not itself set highlight-changes mode."

  t		;; init-value
  nil		;; lighter
  nil		;; keymap

  (hilit-chg-update)
  )


(defun hilit-chg-cust-fix-changes-face-list (w wc &optional event)
  ;; When customization function `highlight-changes-face-list' inserts a new
  ;; face it uses the default face.  We don't want the user to modify this
  ;; face, so we rename the faces in the list on an insert.  The rename is
  ;; actually done by copying the faces so user-defined faces still remain
  ;; in the same order.
  ;; The notifying the parent is needed because without it changes to the
  ;; faces are saved but not to the actual list itself.
  (let ((old-list (widget-value w)))
    (if (member 'default old-list)
	(let
	    ((p (reverse old-list))
	     (n (length old-list))
	     new-name old-name
	     (new-list nil)
	     )
	  (while p
	    (setq old-name (car p))
	    (setq new-name (intern (format "highlight-changes-%d" n)))
	    (if (eq old-name new-name)
		nil
	      ;; A new face has been inserted: we don't want to modify the
	      ;; default face so copy it.  Better, though, (I think) is to
	      ;; make a new face have the same attributes as
	      ;; the `highlight-changes' face.
	      (if (eq old-name 'default)
		  (copy-face 'highlight-changes new-name)
		(copy-face old-name new-name)
		))
	    (setq new-list (append (list new-name) new-list))
	    (setq n (1- n))
	    (setq p (cdr p)))
	  (if (equal new-list (widget-value w))
	      nil ;; (message "notify: no change!")
	    (widget-value-set w new-list)
	    (widget-setup)
	    )
	  )
      ;; (message "notify: no default here!")
      ))
  (let ((parent (widget-get w :parent)))
    (when parent
      (widget-apply parent :notify w event))))


(defcustom highlight-changes-face-list nil
  "A list of faces used when rotating changes.
Normally the variable is initialized to nil and the list is created from
`highlight-changes-colors' when needed.  However, you can set this variable
to any list of faces.  You will have to do this if you want faces which
don't just differ from the `highlight-changes' face by the foreground color.
Otherwise, this list will be constructed when needed from
`highlight-changes-colors'."
  :type '(choice
	  (repeat
	    :notify hilit-chg-cust-fix-changes-face-list
	    face  )
	  (const :tag "Derive from highlight-changes-colors"  nil)
	  )
  :group 'highlight-changes)


(defun hilit-chg-map-changes (func &optional start-position end-position)
  "Call function FUNC for each region used by Highlight Changes mode.
If START-POSITION is nil, (point-min) is used.
If END-POSITION is nil, (point-max) is used.
FUNC is called with 3 params: PROPERTY START STOP."
  (let ((start (or start-position (point-min)))
	(limit (or end-position (point-max)))
	prop end)
    (while (and start (< start limit))
      (setq prop (get-text-property start 'hilit-chg))
      (setq end (text-property-not-all start limit 'hilit-chg prop))
      (if prop
	  (funcall func prop start (or end limit)))
      (setq start end))))


(defun hilit-chg-display-changes (&optional beg end)
  "Display face information for Highlight Changes mode.

An overlay from BEG to END containing a change face is added from the
information in the text property of type `hilit-chg'.

This is the opposite of `hilit-chg-hide-changes'."
  (hilit-chg-map-changes 'hilit-chg-make-ov beg end))


(defun hilit-chg-make-ov (prop start end)
  (or prop
      (error "hilit-chg-make-ov: prop is nil"))
  ;; For the region create overlays with a distincive face
  ;; and the text property 'hilit-chg.
  (let ((ov (make-overlay start end))
	(face (if (eq prop 'hilit-chg-delete)
                  'highlight-changes-delete
                (nth 1 (member prop hilit-chg-list)))))
    (if face
	(progn
	  ;; We must mark the face, that is the purpose of the overlay.
	  (overlay-put ov 'face face)
	  ;; I don't think we need to set evaporate since we should
	  ;; be controlling them!
	  (overlay-put ov 'evaporate t)
	  ;; We set the change property so we can tell this is one
	  ;; of our overlays (so we don't delete someone else's).
	  (overlay-put ov 'hilit-chg t)
	  )
      (error "hilit-chg-make-ov: no face for prop: %s" prop))))

(defun hilit-chg-hide-changes (&optional beg end)
  "Remove face information for Highlight Changes mode.

The overlay containing the face is removed, but the text property
containing the change information is retained.

This is the opposite of `hilit-chg-display-changes'."
  (let ((start (or beg (point-min)))
	(limit (or end (point-max))))
    (dolist (p (overlays-in start limit))
      ;; don't delete the overlay if it isn't ours!
      (if (overlay-get p 'hilit-chg)
	  (delete-overlay p)))))


(defun hilit-chg-fixup (beg end)
  "Fix change overlays in region between BEG and END.

Ensure the overlays agree with the changes as determined from
the text properties of type `hilit-chg'."
  ;; Remove or alter overlays in region beg..end
  (remove-overlays beg end 'hilit-chg t)
  (hilit-chg-display-changes beg end))

;; Inspired by font-lock.  Something like this should be moved to subr.el.
(defmacro highlight-save-buffer-state (&rest body)
  "Bind variables according to VARLIST and eval BODY restoring buffer state."
  (declare (indent 0) (debug t))
  (let ((modified (make-symbol "modified")))
    `(let* ((,modified (buffer-modified-p))
            (inhibit-modification-hooks t)
            deactivate-mark
            ;; So we don't check the file's mtime.
            buffer-file-name
            buffer-file-truename)
       (progn
         ,@body)
       (unless ,modified
         (restore-buffer-modified-p nil)))))

;;;###autoload
(defun highlight-changes-remove-highlight (beg end)
  "Remove the change face from the region between BEG and END.
This allows you to manually remove highlighting from uninteresting changes."
  (interactive "r")
  (highlight-save-buffer-state
    (remove-text-properties beg end '(hilit-chg nil))
    (hilit-chg-fixup beg end)))

(defun hilit-chg-set-face-on-change (beg end leng-before
					 &optional no-property-change)
  "Record changes and optionally display them in a distinctive face.
`hilit-chg-set' adds this function to the `after-change-functions' hook."
  ;;
  ;; This function is called by the `after-change-functions' hook, which
  ;; is how we are notified when text is changed.
  ;; It is also called from `highlight-compare-with-file'.
  ;;
  ;; We do NOT want to simply do this if this is an undo command, because
  ;; otherwise an undone change shows up as changed.  While the properties
  ;; are automatically restored by undo, we must fix up the overlay.
  (save-match-data
    (let ((beg-decr 1) (end-incr 1)
	  (type 'hilit-chg)
	  old)
      (if undo-in-progress
	  (if (and highlight-changes-mode
		   highlight-changes-visible-mode)
	      (hilit-chg-fixup beg end))
        (highlight-save-buffer-state
          (if (and (= beg end) (> leng-before 0))
              ;; deletion
              (progn
                ;; The eolp and bolp tests are a kludge!  But they prevent
                ;; rather nasty looking displays when deleting text at the end
                ;; of line, such as normal corrections as one is typing and
                ;; immediately makes a correction, and when deleting first
                ;; character of a line.
                ;; (if (= leng-before 1)
                ;;     (if (eolp)
                ;;         (setq beg-decr 0 end-incr 0)
                ;;       (if (bolp)
                ;;   	(setq beg-decr 0))))
                ;; (setq beg (max (- beg beg-decr) (point-min)))
                (setq end (min (+ end end-incr) (point-max)))
                (setq type 'hilit-chg-delete))
            ;; Not a deletion.
            ;; Most of the time the following is not necessary, but
            ;; if the current text was marked as a deletion then
            ;; the old overlay is still in effect, so if we add some
            ;; text then remove the deletion marking, but set it to
	  ;; changed otherwise its highlighting disappears.
	  (if (eq (get-text-property end 'hilit-chg) 'hilit-chg-delete)
	      (progn
		(put-text-property end (+ end 1) 'hilit-chg 'hilit-chg)
		(if highlight-changes-visible-mode
		    (hilit-chg-fixup beg (+ end 1))))))
          (unless no-property-change
            (put-text-property beg end 'hilit-chg type))
          (if (or highlight-changes-visible-mode no-property-change)
              (hilit-chg-make-ov type beg end)))))))

(defun hilit-chg-update ()
  "Update a buffer's highlight changes when visibility changed."
  (if highlight-changes-visible-mode
      ;; changes are visible
      (progn
	(setq hilit-chg-string highlight-changes-visible-string)
	(or buffer-read-only
	    (hilit-chg-display-changes)))
    ;; changes are invisible
    (setq hilit-chg-string highlight-changes-invisible-string)
    (or buffer-read-only
	(hilit-chg-hide-changes))))

(defun hilit-chg-set ()
  "Turn on Highlight Changes mode for this buffer."
  (remove-hook 'after-change-functions 'hilit-chg-set-face-on-change t)
  (hilit-chg-make-list)
  (setq highlight-changes-mode t)
  (setq highlight-changes-visible-mode highlight-changes-visibility-initial-state)
  (hilit-chg-update)
  (force-mode-line-update)
  (add-hook 'after-change-functions 'hilit-chg-set-face-on-change nil t))

(defun hilit-chg-clear ()
  "Remove Highlight Changes mode for this buffer.
This removes all saved change information."
  (if buffer-read-only
      ;; We print the buffer name because this function could be called
      ;; on many buffers from `global-highlight-changes-mode'.
      (message "Cannot remove highlighting from read-only mode buffer %s"
	       (buffer-name))
    (remove-hook 'after-change-functions 'hilit-chg-set-face-on-change t)
    (highlight-save-buffer-state
      (hilit-chg-hide-changes)
      (hilit-chg-map-changes
       (lambda (prop start stop)
         (remove-text-properties start stop '(hilit-chg nil)))))
    (setq highlight-changes-mode nil)
    (force-mode-line-update)))


;;;###autoload
(defun highlight-changes-next-change ()
  "Move to the beginning of the next change, if in Highlight Changes mode."
  (interactive)
  (if highlight-changes-mode
      (let ((start (point))
	    prop)
	(setq prop (get-text-property (point) 'hilit-chg))
	(if prop
	    ;; we are in a change
	    (setq start (next-single-property-change (point) 'hilit-chg)))
	(if start
	    (setq start (next-single-property-change start 'hilit-chg)))
	(if start
	    (goto-char start)
	  (message "no next change")))
    (message "This buffer is not in Highlight Changes mode.")))


;;;###autoload
(defun highlight-changes-previous-change ()
  "Move to the beginning of the previous change, if in Highlight Changes mode."
  (interactive)
  (if highlight-changes-mode
      (let ( (start (point)) (prop nil) )
	(or (bobp)
	    (setq prop (get-text-property (1- (point)) 'hilit-chg)))
	(if prop
	    ;; we are in a change
	    (setq start (previous-single-property-change (point) 'hilit-chg)))
	(if start
	    (setq start (previous-single-property-change start 'hilit-chg)))
	;; special handling for the case where (point-min) is a change
	(if start
	    (setq start (or (previous-single-property-change start 'hilit-chg)
			    (if (get-text-property (point-min) 'hilit-chg)
				(point-min)))))
	(if start
	    (goto-char start)
	  (message "no previous change")))
    (message "This buffer is not in Highlight Changes mode.")))

;; ========================================================================

(defun hilit-chg-make-list (&optional force)
  "Construct `hilit-chg-list' and `highlight-changes-face-list'."
  ;; Constructs highlight-changes-face-list if necessary,
  ;; and hilit-chg-list always:
  ;; Maybe this should always be called when rotating a face
  ;; so we pick up any changes?
  (if (or (null highlight-changes-face-list)  ; Don't do it if it
	  force) ; already exists unless FORCE non-nil.
      (let ((p highlight-changes-colors)
	    (n 1) name)
	(setq highlight-changes-face-list nil)
	(while p
	  (setq name (intern (format "highlight-changes-%d" n)))
	  (copy-face 'highlight-changes name)
	  (set-face-foreground name (car p))
	  (setq highlight-changes-face-list
		(append highlight-changes-face-list (list name)))
	  (setq p (cdr p))
	  (setq n (1+ n)))))
  (setq hilit-chg-list (list 'hilit-chg 'highlight-changes))
  (let ((p highlight-changes-face-list)
	(n 1)
	last-category last-face)
    (while p
      (setq last-category (intern (format "change-%d" n)))
      ;; (setq last-face (intern (format "highlight-changes-%d" n)))
      (setq last-face (car p))
      (setq hilit-chg-list
	    (append hilit-chg-list
		    (list last-category last-face)))
      (setq p (cdr p))
      (setq n (1+ n)))
    (setq hilit-chg-list
	  (append hilit-chg-list
		  (list last-category last-face)))))

(defun hilit-chg-bump-change (prop start end)
  "Increment (age) the Highlight Changes mode text property."
  (let ( new-prop )
    (if (eq prop 'hilit-chg-delete)
	(setq new-prop (nth 2 hilit-chg-list))
      (setq new-prop (nth 2 (member prop hilit-chg-list))))
    (if prop
	(put-text-property start end 'hilit-chg new-prop)
      (message "%d-%d unknown property %s not changed" start end prop))))

;;;###autoload
(defun highlight-changes-rotate-faces ()
  "Rotate the faces if in Highlight Changes mode and the changes are visible.

Current changes are displayed in the face described by the first element
of `highlight-changes-face-list', one level older changes are shown in
face described by the second element, and so on.  Very old changes remain
shown in the last face in the list.

You can automatically rotate colors when the buffer is saved by adding
this function to `write-file-functions' as a buffer-local value.  To do
this, eval the following in the buffer to be saved:

  \(add-hook 'write-file-functions 'highlight-changes-rotate-faces nil t)"
  (interactive)
  (when (and highlight-changes-mode highlight-changes-visible-mode)
    (let ((modified (buffer-modified-p))
	  (inhibit-modification-hooks t))
      ;; The `modified' related code tries to combine two goals: (1) Record the
      ;; rotation in `buffer-undo-list' and (2) avoid setting the modified flag
      ;; of the current buffer due to the rotation.  We do this by inserting (in
      ;; `buffer-undo-list') entries restoring buffer-modified-p to nil before
      ;; and after the entry for the rotation.
      ;; FIXME: this is no good: we need to test the `modified' state at the
      ;; time of the undo, not at the time of the "do", otherwise the undo
      ;; may erroneously clear the modified flag.  --Stef
      ;; (unless modified
      ;;   ;; Install the "before" entry.
      ;;   (push '(apply restore-buffer-modified-p nil) buffer-undo-list))
      (unwind-protect
	  (progn
	    ;; ensure hilit-chg-list is made and up to date
	    (hilit-chg-make-list)
	    ;; remove our existing overlays
	    (hilit-chg-hide-changes)
	    ;; for each change text property, increment it
	    (hilit-chg-map-changes 'hilit-chg-bump-change)
	    ;; and display them
	    (hilit-chg-display-changes))
	(unless modified
	  ;; Install the "after" entry.  FIXME: See above.
	  ;; (push '(apply restore-buffer-modified-p nil) buffer-undo-list)

	  (restore-buffer-modified-p nil)))))
  ;; This always returns nil so it is safe to use in write-file-functions
  nil)

;; ========================================================================
;; Comparing buffers/files
;; These use ediff to find the differences.

(defun highlight-markup-buffers
  (buf-a file-a buf-b file-b &optional markup-a-only)
  "Get differences between two buffers and set highlight changes.
Both buffers are done unless optional parameter MARKUP-A-ONLY
is non-nil."
  (eval-and-compile
    (require 'ediff-util))
  (save-window-excursion
    (let* (change-info
	   change-a change-b
	   a-start a-end len-a
	   b-start b-end len-b
	   (bufa-modified (buffer-modified-p buf-a))
	   (bufb-modified (buffer-modified-p buf-b))
	   (buf-a-read-only (with-current-buffer buf-a buffer-read-only))
	   (buf-b-read-only (with-current-buffer buf-b buffer-read-only))
	   temp-a temp-b)
      (if (and file-a bufa-modified)
	  (if (y-or-n-p (format "Save buffer %s?  " buf-a))
	      (with-current-buffer buf-a
		(save-buffer)
		(setq bufa-modified (buffer-modified-p buf-a)))
	    (setq file-a nil)))
      (or file-a
	  (setq temp-a (setq file-a (ediff-make-temp-file buf-a nil))))

      (if (and file-b bufb-modified)
	  (if (y-or-n-p (format "Save buffer %s?  " buf-b))
	      (with-current-buffer buf-b
		(save-buffer)
		(setq bufb-modified (buffer-modified-p buf-b)))
	    (setq file-b nil)))
      (or file-b
	  (setq temp-b (setq file-b (ediff-make-temp-file buf-b nil))))
      (set-buffer buf-a)
      (highlight-changes-mode 1)
      (or markup-a-only (with-current-buffer buf-b
			  (highlight-changes-mode 1)))
      (setq change-info (hilit-chg-get-diff-info buf-a file-a buf-b file-b))


      (setq change-a (car change-info))
      (setq change-b (car (cdr change-info)))

      (hilit-chg-make-list)
      (while change-a
	(setq a-start (nth 0 (car change-a)))
	(setq a-end (nth 1 (car change-a)))
	(setq b-start (nth 0 (car change-b)))
	(setq b-end (nth 1 (car change-b)))
	(setq len-a (- a-end a-start))
	(setq len-b (- b-end b-start))
	(set-buffer buf-a)
	(hilit-chg-set-face-on-change a-start a-end len-b buf-a-read-only)
	(or markup-a-only
	    (with-current-buffer buf-b
	      (hilit-chg-set-face-on-change b-start b-end len-a
					    buf-b-read-only)
	      ))
	(setq change-a (cdr change-a))
	(setq change-b (cdr change-b)))
      (or bufa-modified
	  (with-current-buffer buf-a (set-buffer-modified-p nil)))
      (or bufb-modified
	  (with-current-buffer buf-b (set-buffer-modified-p nil)))
      (if temp-a
	  (delete-file temp-a))
      (if temp-b
	  (delete-file temp-b)))
    ))

;;;###autoload
(defun highlight-compare-buffers (buf-a buf-b)
"Compare two buffers and highlight the differences.

The default is the current buffer and the one in the next window.

If either buffer is modified and is visiting a file, you are prompted
to save the file.

Unless the buffer is unmodified and visiting a file, the buffer is
written to a temporary file for comparison.

If a buffer is read-only, differences will be highlighted but no property
changes are made, so \\[highlight-changes-next-change] and
\\[highlight-changes-previous-change] will not work."
  (interactive
   (list
    (get-buffer (read-buffer "buffer-a " (current-buffer) t))
    (get-buffer
     (read-buffer "buffer-b "
		  (window-buffer (next-window (selected-window))) t))))
  (let ((file-a (buffer-file-name buf-a))
	(file-b (buffer-file-name buf-b)))
    (highlight-markup-buffers buf-a file-a buf-b file-b)
    ))

;;;###autoload
(defun highlight-compare-with-file (file-b)
  "Compare this buffer with a file, and highlight differences.

If the buffer has a backup filename, it is used as the default when
this function is called interactively.

If the current buffer is visiting the file being compared against, it
also will have its differences highlighted.  Otherwise, the file is
read in temporarily but the buffer is deleted.

If the buffer is read-only, differences will be highlighted but no property
changes are made, so \\[highlight-changes-next-change] and
\\[highlight-changes-previous-change] will not work."
  (interactive
   (let ((file buffer-file-name)
	 (file-name nil)
	 (file-dir nil))
     (and file
	  (setq file-name (file-name-nondirectory file)
		file-dir (file-name-directory file)))
     (setq file-name (make-backup-file-name file-name))
     (unless (file-exists-p file-name)
	     (setq file-name nil))
     (list (read-file-name
	    "Find to compare with: "	;; prompt
	    file-dir			;; directory
	    nil				;; default
	    nil				;; existing
	    file-name)			;; initial
	   )))
  (let* ((buf-a (current-buffer))
	 (file-a (buffer-file-name))
	 (existing-buf (get-file-buffer file-b))
	 (buf-b (or existing-buf
		    (find-file-noselect file-b)))
	 (buf-b-read-only (with-current-buffer buf-b buffer-read-only)))
    (highlight-markup-buffers buf-a file-a buf-b file-b (not existing-buf))
    (unless existing-buf
      (kill-buffer buf-b))
    ))


(defun hilit-chg-get-diff-info (buf-a file-a buf-b file-b)
  (let ((e nil) x y)   ;; e is set by function hilit-chg-get-diff-list-hk
    (ediff-setup buf-a file-a buf-b file-b
	       nil nil   ; buf-c file-C
	       'hilit-chg-get-diff-list-hk
	       (list (cons 'ediff-job-name 'something))
	       )
    (ediff-with-current-buffer e (ediff-really-quit nil))
    (list x y)))


(defun hilit-chg-get-diff-list-hk ()
  ;; x and y are dynamically bound by hilit-chg-get-diff-info
  ;; which calls this function as a hook
  (defvar x)  ;; placate the byte-compiler
  (defvar y)
  (setq e (current-buffer))
  (let ((n 0) extent p va vb a b)
    (setq x nil y nil)    ;; x and y are bound by hilit-chg-get-diff-info
    (while (< n ediff-number-of-differences)
      (ediff-make-fine-diffs n)
      (setq va (ediff-get-fine-diff-vector n 'A))
      ;; va is a vector if there are fine differences
      (if va
	  (setq a (append va nil))
	;; if not, get the unrefined difference
	(setq va (ediff-get-difference n 'A))
	(setq a (list (elt va 0))))
      ;; a list a list
      (setq p a)
      (while p
	(setq extent (list (overlay-start (car p))
			   (overlay-end (car p))))
	(setq p (cdr p))
	(setq x (append x (list extent) )));; while p
      ;;
      (setq vb (ediff-get-fine-diff-vector n 'B))
      ;; vb is a vector
      (if vb
	  (setq b (append vb nil))
	;; if not, get the unrefined difference
	(setq vb (ediff-get-difference n 'B))
	(setq b (list (elt vb 0))))
      ;; b list a list
      (setq p b)
      (while p
	(setq extent (list (overlay-start (car p))
			   (overlay-end (car p))))
	(setq p (cdr p))
	(setq y (append y (list extent) )))
      (setq n (1+ n)));; while
    ;; ediff-quit doesn't work here.
    ;; No point in returning a value, since this is a hook function.
    ))

;; ======================= global-highlight-changes-mode ==============

;;;###autoload
(define-globalized-minor-mode global-highlight-changes-mode
  highlight-changes-mode highlight-changes-mode-turn-on)

(define-obsolete-function-alias
 'global-highlight-changes
  'global-highlight-changes-mode "23.1")

(defun highlight-changes-mode-turn-on ()
  "See if Highlight Changes mode should be turned on for this buffer.
This is called when `global-highlight-changes-mode' is turned on."
  (or highlight-changes-mode			; do nothing if already on
      (if
	  (cond
	   ((null highlight-changes-global-modes)
	    nil)
	   ((functionp highlight-changes-global-modes)
	    (funcall highlight-changes-global-modes))
	    ((listp highlight-changes-global-modes)
	     (if (eq (car-safe highlight-changes-global-modes) 'not)
		 (not (memq major-mode (cdr highlight-changes-global-modes)))
	       (memq major-mode highlight-changes-global-modes)))
	    (t
	     (and
	      (not (string-match "^[ *]" (buffer-name)))
	      (buffer-file-name))))
	  (highlight-changes-mode 1))
	))


;;;; Desktop support.

;; Called by `desktop-create-buffer' to restore `highlight-changes-mode'.
(defun hilit-chg-desktop-restore (desktop-buffer-locals)
  (highlight-changes-mode
   (or (cdr (assq 'highlight-changes-mode desktop-buffer-locals)) 1)))

(add-to-list 'desktop-minor-mode-handlers
             '(highlight-changes-mode . hilit-chg-desktop-restore))

(add-to-list 'desktop-locals-to-save 'highlight-changes-mode)

;; ===================== debug ==================
;; For debug & test use:
;;
;; (defun hilit-chg-debug-show (&optional beg end)
;;   (interactive)
;;   (message "--- hilit-chg-debug-show ---")
;;   (hilit-chg-map-changes '(lambda (prop start end)
;; 			      (message "%d-%d: %s" start end prop)
;; 			      )
;; 			   beg end
;; 			   ))
;;
;; ================== end of debug ===============

(provide 'hilit-chg)

;; arch-tag: de00301d-5bad-44da-aa82-e0e010b0c463
;;; hilit-chg.el ends here