1. Nic Ferrier
  2. emacs

Source

emacs / lisp / hilit-chg.el

   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, 2009 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