summaryrefslogtreecommitdiff
path: root/lisp/help.el
blob: d3aaa1e251de196668e4abe8fd42832338838303 (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
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
;;; help.el --- help commands for Emacs

;; Copyright (C) 1985-1986, 1993-1994, 1998-2017 Free Software
;; Foundation, Inc.

;; Maintainer: emacs-devel@gnu.org
;; Keywords: help, internal
;; Package: emacs

;; 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:

;; This code implements GNU Emacs's built-in help system, the one invoked by
;; `M-x help-for-help'.

;;; Code:

;; Get the macro make-help-screen when this is compiled,
;; or run interpreted, but not when the compiled code is loaded.
(eval-when-compile (require 'help-macro))

;; This makes `with-output-to-temp-buffer' buffers use `help-mode'.
(add-hook 'temp-buffer-setup-hook 'help-mode-setup)
(add-hook 'temp-buffer-show-hook 'help-mode-finish)

;; `help-window-point-marker' is a marker you can move to a valid
;; position of the buffer shown in the help window in order to override
;; the standard positioning mechanism (`point-min') chosen by
;; `with-output-to-temp-buffer' and `with-temp-buffer-window'.
;; `with-help-window' has this point nowhere before exiting.  Currently
;; used by `view-lossage' to assert that the last keystrokes are always
;; visible.
(defvar help-window-point-marker (make-marker)
  "Marker to override default `window-point' in help windows.")

(defvar help-window-old-frame nil
  "Frame selected at the time `with-help-window' is invoked.")

(defvar help-map
  (let ((map (make-sparse-keymap)))
    (define-key map (char-to-string help-char) 'help-for-help)
    (define-key map [help] 'help-for-help)
    (define-key map [f1] 'help-for-help)
    (define-key map "." 'display-local-help)
    (define-key map "?" 'help-for-help)

    (define-key map "\C-a" 'about-emacs)
    (define-key map "\C-c" 'describe-copying)
    (define-key map "\C-d" 'view-emacs-debugging)
    (define-key map "\C-e" 'view-external-packages)
    (define-key map "\C-f" 'view-emacs-FAQ)
    (define-key map "\C-m" 'view-order-manuals)
    (define-key map "\C-n" 'view-emacs-news)
    (define-key map "\C-o" 'describe-distribution)
    (define-key map "\C-p" 'view-emacs-problems)
    (define-key map "\C-t" 'view-emacs-todo)
    (define-key map "\C-w" 'describe-no-warranty)

    ;; This does not fit the pattern, but it is natural given the C-\ command.
    (define-key map "\C-\\" 'describe-input-method)

    (define-key map "C" 'describe-coding-system)
    (define-key map "F" 'Info-goto-emacs-command-node)
    (define-key map "I" 'describe-input-method)
    (define-key map "K" 'Info-goto-emacs-key-command-node)
    (define-key map "L" 'describe-language-environment)
    (define-key map "S" 'info-lookup-symbol)

    (define-key map "a" 'apropos-command)
    (define-key map "b" 'describe-bindings)
    (define-key map "c" 'describe-key-briefly)
    (define-key map "d" 'apropos-documentation)
    (define-key map "e" 'view-echo-area-messages)
    (define-key map "f" 'describe-function)
    (define-key map "g" 'describe-gnu-project)
    (define-key map "h" 'view-hello-file)

    (define-key map "i" 'info)
    (define-key map "4i" 'info-other-window)

    (define-key map "k" 'describe-key)
    (define-key map "l" 'view-lossage)
    (define-key map "m" 'describe-mode)
    (define-key map "o" 'describe-symbol)
    (define-key map "n" 'view-emacs-news)
    (define-key map "p" 'finder-by-keyword)
    (define-key map "P" 'describe-package)
    (define-key map "r" 'info-emacs-manual)
    (define-key map "s" 'describe-syntax)
    (define-key map "t" 'help-with-tutorial)
    (define-key map "w" 'where-is)
    (define-key map "v" 'describe-variable)
    (define-key map "q" 'help-quit)
    map)
  "Keymap for characters following the Help key.")

(define-key global-map (char-to-string help-char) 'help-command)
(define-key global-map [help] 'help-command)
(define-key global-map [f1] 'help-command)
(fset 'help-command help-map)

;; insert-button makes the action nil if it is not store somewhere
(defvar help-button-cache nil)


(defun help-quit ()
  "Just exit from the Help command's command loop."
  (interactive)
  nil)

(defvar help-return-method nil
  "What to do to \"exit\" the help buffer.
This is a list
 (WINDOW . t)              delete the selected window (and possibly its frame,
                           see `quit-window'), go to WINDOW.
 (WINDOW . quit-window)    do quit-window, then select WINDOW.
 (WINDOW BUF START POINT)  display BUF at START, POINT, then select WINDOW.")

(define-obsolete-function-alias 'print-help-return-message 'help-print-return-message "23.2")
(defun help-print-return-message (&optional function)
  "Display or return message saying how to restore windows after help command.
This function assumes that `standard-output' is the help buffer.
It computes a message, and applies the optional argument FUNCTION to it.
If FUNCTION is nil, it applies `message', thus displaying the message.
In addition, this function sets up `help-return-method', which see, that
specifies what to do when the user exits the help buffer.

Do not call this in the scope of `with-help-window'."
  (and (not (get-buffer-window standard-output))
       (let ((first-message
	      (cond ((or
		      pop-up-frames
		      (special-display-p (buffer-name standard-output)))
		     (setq help-return-method (cons (selected-window) t))
		     ;; If the help output buffer is a special display buffer,
		     ;; don't say anything about how to get rid of it.
		     ;; First of all, the user will do that with the window
		     ;; manager, not with Emacs.
		     ;; Secondly, the buffer has not been displayed yet,
		     ;; so we don't know whether its frame will be selected.
		     nil)
		    ((not (one-window-p t))
		     (setq help-return-method
			   (cons (selected-window) 'quit-window))
		     "Type \\[display-buffer] RET to restore the other window.")
		    (pop-up-windows
		     (setq help-return-method (cons (selected-window) t))
		     "Type \\[delete-other-windows] to remove help window.")
		    (t
		     (setq help-return-method
			   (list (selected-window) (window-buffer)
				 (window-start) (window-point)))
		     "Type \\[switch-to-buffer] RET to remove help window."))))
	 (funcall (or function 'message)
		  (concat
		   (if first-message
		       (substitute-command-keys first-message))
		   (if first-message "  ")
		   ;; If the help buffer will go in a separate frame,
		   ;; it's no use mentioning a command to scroll, so don't.
		   (if (or pop-up-windows
			   (special-display-p (buffer-name standard-output)))
		       nil
		     (if (same-window-p (buffer-name standard-output))
			 ;; Say how to scroll this window.
			 (substitute-command-keys
			  "\\[scroll-up] to scroll the help.")
		       ;; Say how to scroll some other window.
		       (substitute-command-keys
			"\\[scroll-other-window] to scroll the help."))))))))

;; So keyboard macro definitions are documented correctly
(fset 'defining-kbd-macro (symbol-function 'start-kbd-macro))

(defalias 'help 'help-for-help-internal)
;; find-function can find this.
(defalias 'help-for-help 'help-for-help-internal)
;; It can't find this, but nobody will look.
(make-help-screen help-for-help-internal
  (purecopy "Type a help option: [abcCdefFgiIkKlLmnprstvw.] C-[cdefmnoptw] or ?")
  ;; Don't purecopy this one, because it's not evaluated (it's
  ;; directly used as a docstring in a function definition, so it'll
  ;; be moved to the DOC file anyway: no need for purecopying it).
  "You have typed %THIS-KEY%, the help character.  Type a Help option:
\(Use SPC or DEL to scroll through this text.  Type \\<help-map>\\[help-quit] to exit the Help command.)

a PATTERN   Show commands whose name matches the PATTERN (a list of words
              or a regexp).  See also the `apropos' command.
b           Display all key bindings.
c KEYS      Display the command name run by the given key sequence.
C CODING    Describe the given coding system, or RET for current ones.
d PATTERN   Show a list of functions, variables, and other items whose
              documentation matches the PATTERN (a list of words or a regexp).
e           Go to the *Messages* buffer which logs echo-area messages.
f FUNCTION  Display documentation for the given function.
F COMMAND   Show the Emacs manual's section that describes the command.
g           Display information about the GNU project.
h           Display the HELLO file which illustrates various scripts.
i           Start the Info documentation reader: read included manuals.
I METHOD    Describe a specific input method, or RET for current.
k KEYS      Display the full documentation for the key sequence.
K KEYS      Show the Emacs manual's section for the command bound to KEYS.
l           Show last 300 input keystrokes (lossage).
L LANG-ENV  Describes a specific language environment, or RET for current.
m           Display documentation of current minor modes and current major mode,
              including their special commands.
n           Display news of recent Emacs changes.
o SYMBOL    Display the given function or variable's documentation and value.
p TOPIC     Find packages matching a given topic keyword.
P PACKAGE   Describe the given Emacs Lisp package.
r           Display the Emacs manual in Info mode.
s           Display contents of current syntax table, plus explanations.
S SYMBOL    Show the section for the given symbol in the Info manual
              for the programming language used in this buffer.
t           Start the Emacs learn-by-doing tutorial.
v VARIABLE  Display the given variable's documentation and value.
w COMMAND   Display which keystrokes invoke the given command (where-is).
.           Display any available local help at point in the echo area.

C-a         Information about Emacs.
C-c         Emacs copying permission (GNU General Public License).
C-d         Instructions for debugging GNU Emacs.
C-e         External packages and information about Emacs.
C-f         Emacs FAQ.
C-m         How to order printed Emacs manuals.
C-n         News of recent Emacs changes.
C-o         Emacs ordering and distribution information.
C-p         Info about known Emacs problems.
C-t         Emacs TODO list.
C-w         Information on absence of warranty for GNU Emacs."
  help-map)



(defun function-called-at-point ()
  "Return a function around point or else called by the list containing point.
If that doesn't give a function, return nil."
  (with-syntax-table emacs-lisp-mode-syntax-table
    (or (condition-case ()
            (save-excursion
              (or (not (zerop (skip-syntax-backward "_w")))
                  (eq (char-syntax (following-char)) ?w)
                  (eq (char-syntax (following-char)) ?_)
                  (forward-sexp -1))
              (skip-chars-forward "'")
              (let ((obj (read (current-buffer))))
                (and (symbolp obj) (fboundp obj) obj)))
          (error nil))
        (condition-case ()
            (save-excursion
              (save-restriction
                (narrow-to-region (max (point-min)
                                       (- (point) 1000)) (point-max))
                ;; Move up to surrounding paren, then after the open.
                (backward-up-list 1)
                (forward-char 1)
                ;; If there is space here, this is probably something
                ;; other than a real Lisp function call, so ignore it.
                (if (looking-at "[ \t]")
                    (error "Probably not a Lisp function call"))
                (let ((obj (read (current-buffer))))
                  (and (symbolp obj) (fboundp obj) obj))))
          (error nil))
        (let* ((str (find-tag-default))
               (sym (if str (intern-soft str))))
          (if (and sym (fboundp sym))
              sym
            (save-match-data
              (when (and str (string-match "\\`\\W*\\(.*?\\)\\W*\\'" str))
                (setq sym (intern-soft (match-string 1 str)))
                (and (fboundp sym) sym))))))))


;;; `User' help functions

(defun view-help-file (file &optional dir)
  (view-file (expand-file-name file (or dir data-directory)))
  (goto-address-mode 1)
  (goto-char (point-min)))

(defun describe-distribution ()
  "Display info on how to obtain the latest version of GNU Emacs."
  (interactive)
  (view-help-file "DISTRIB"))

(defun describe-copying ()
  "Display info on how you may redistribute copies of GNU Emacs."
  (interactive)
  (view-help-file "COPYING"))

;; Maybe this command should just be removed.
(defun describe-gnu-project ()
  "Browse online information on the GNU project."
  (interactive)
  (browse-url "http://www.gnu.org/gnu/thegnuproject.html"))

(define-obsolete-function-alias 'describe-project 'describe-gnu-project "22.2")

(defun describe-no-warranty ()
  "Display info on all the kinds of warranty Emacs does NOT have."
  (interactive)
  (describe-copying)
  (let (case-fold-search)
    (search-forward "Disclaimer of Warranty")
    (forward-line 0)
    (recenter 0)))

(defun describe-prefix-bindings ()
  "Describe the bindings of the prefix used to reach this command.
The prefix described consists of all but the last event
of the key sequence that ran this command."
  (interactive)
  (let ((key (this-command-keys)))
    (describe-bindings
     (if (stringp key)
	 (substring key 0 (1- (length key)))
       (let ((prefix (make-vector (1- (length key)) nil))
	     (i 0))
	 (while (< i (length prefix))
	   (aset prefix i (aref key i))
	   (setq i (1+ i)))
	 prefix)))))
;; Make C-h after a prefix, when not specifically bound,
;; run describe-prefix-bindings.
(setq prefix-help-command 'describe-prefix-bindings)

(defun view-emacs-news (&optional version)
  "Display info on recent changes to Emacs.
With argument, display info only for the selected version."
  (interactive "P")
  (unless version
    (setq version emacs-major-version))
  (when (consp version)
    (let* ((all-versions
	    (let (res)
	      (mapc
	       (lambda (file)
		 (with-temp-buffer
		   (insert-file-contents
		    (expand-file-name file data-directory))
		   (while (re-search-forward
			   (if (member file '("NEWS.18" "NEWS.1-17"))
			       "Changes in \\(?:Emacs\\|version\\)?[ \t]*\\([0-9]+\\(?:\\.[0-9]+\\)?\\)"
			     "^\\* [^0-9\n]*\\([0-9]+\\.[0-9]+\\)") nil t)
		     (setq res (cons (match-string-no-properties 1) res)))))
	       (cons "NEWS"
		     (directory-files data-directory nil
				      "^NEWS\\.[0-9][-0-9]*$" nil)))
	      (sort (delete-dups res) #'string>)))
	   (current (car all-versions)))
      (setq version (completing-read
		     (format "Read NEWS for the version (default %s): " current)
		     all-versions nil nil nil nil current))
      (if (integerp (string-to-number version))
	  (setq version (string-to-number version))
	(unless (or (member version all-versions)
		    (<= (string-to-number version) (string-to-number current)))
	  (error "No news about version %s" version)))))
  (when (integerp version)
    (cond ((<= version 12)
	   (setq version (format "1.%d" version)))
	  ((<= version 18)
	   (setq version (format "%d" version)))
	  ((> version emacs-major-version)
	   (error "No news about Emacs %d (yet)" version))))
  (let* ((vn (if (stringp version)
		 (string-to-number version)
	       version))
	 (file (cond
		((>= vn emacs-major-version) "NEWS")
		((< vn 18) "NEWS.1-17")
		(t (format "NEWS.%d" vn))))
	 res)
    (view-file (expand-file-name file data-directory))
    (widen)
    (goto-char (point-min))
    (when (stringp version)
      (when (re-search-forward
	     (concat (if (< vn 19)
			 "Changes in Emacs[ \t]*"
		       "^\\* [^0-9\n]*") version "$")
	     nil t)
	(beginning-of-line)
	(narrow-to-region
	 (point)
	 (save-excursion
	   (while (and (setq res
			     (re-search-forward
			      (if (< vn 19)
				  "Changes in \\(?:Emacs\\|version\\)?[ \t]*\\([0-9]+\\(?:\\.[0-9]+\\)?\\)"
				"^\\* [^0-9\n]*\\([0-9]+\\.[0-9]+\\)") nil t))
		       (equal (match-string-no-properties 1) version)))
	   (or res (goto-char (point-max)))
	   (beginning-of-line)
	   (point)))))))

(defun view-emacs-todo (&optional _arg)
  "Display the Emacs TODO list."
  (interactive "P")
  (view-help-file "TODO"))

(define-obsolete-function-alias 'view-todo 'view-emacs-todo "22.2")


(defun view-echo-area-messages ()
  "View the log of recent echo-area messages: the `*Messages*' buffer.
The number of messages retained in that buffer
is specified by the variable `message-log-max'."
  (interactive)
  (with-current-buffer (messages-buffer)
    (goto-char (point-max))
    (display-buffer (current-buffer))))

(defun view-order-manuals ()
  "Display information on how to buy printed copies of Emacs manuals."
  (interactive)
;;  (view-help-file "ORDERS")
  (info "(emacs)Printed Books"))

(defun view-emacs-FAQ ()
  "Display the Emacs Frequently Asked Questions (FAQ) file."
  (interactive)
  ;; (find-file-read-only (expand-file-name "FAQ" data-directory))
  (info "(efaq)"))

(defun view-emacs-problems ()
  "Display info on known problems with Emacs and possible workarounds."
  (interactive)
  (view-help-file "PROBLEMS"))

(defun view-emacs-debugging ()
  "Display info on how to debug Emacs problems."
  (interactive)
  (view-help-file "DEBUG"))

;; This used to visit MORE.STUFF; maybe it should just be removed.
(defun view-external-packages ()
  "Display info on where to get more Emacs packages."
  (interactive)
  (info "(efaq)Packages that do not come with Emacs"))

(defun view-lossage ()
  "Display last few input keystrokes and the commands run.

To record all your input, use `open-dribble-file'."
  (interactive)
  (help-setup-xref (list #'view-lossage)
		   (called-interactively-p 'interactive))
  (with-help-window (help-buffer)
    (princ " ")
    (princ (mapconcat (lambda (key)
			(cond
			 ((and (consp key) (null (car key)))
			  (format "[%s]\n" (if (symbolp (cdr key)) (cdr key)
					   "anonymous-command")))
			 ((or (integerp key) (symbolp key) (listp key))
			  (single-key-description key))
			 (t
			  (prin1-to-string key nil))))
		      (recent-keys 'include-cmds)
		      " "))
    (with-current-buffer standard-output
      (goto-char (point-min))
      (while (not (eobp))
	(move-to-column 50)
	(unless (eolp)
	  (fill-region (line-beginning-position) (line-end-position)))
	(forward-line 1))
      ;; jidanni wants to see the last keystrokes immediately.
      (set-marker help-window-point-marker (point)))))


;; Key bindings

(defun describe-bindings (&optional prefix buffer)
  "Display a buffer showing a list of all defined keys, and their definitions.
The keys are displayed in order of precedence.

The optional argument PREFIX, if non-nil, should be a key sequence;
then we display only bindings that start with that prefix.
The optional argument BUFFER specifies which buffer's bindings
to display (default, the current buffer).  BUFFER can be a buffer
or a buffer name."
  (interactive)
  (or buffer (setq buffer (current-buffer)))
  (help-setup-xref (list #'describe-bindings prefix buffer)
		   (called-interactively-p 'interactive))
  (with-help-window (help-buffer)
    ;; Be aware that `describe-buffer-bindings' puts its output into
    ;; the current buffer.
    (with-current-buffer (help-buffer)
      (describe-buffer-bindings buffer prefix))))

;; This function used to be in keymap.c.
(defun describe-bindings-internal (&optional menus prefix)
  "Show a list of all defined keys, and their definitions.
We put that list in a buffer, and display the buffer.

The optional argument MENUS, if non-nil, says to mention menu bindings.
\(Ordinarily these are omitted from the output.)
The optional argument PREFIX, if non-nil, should be a key sequence;
then we display only bindings that start with that prefix."
  (declare (obsolete describe-buffer-bindings "24.4"))
  (let ((buf (current-buffer)))
    (with-help-window (help-buffer)
      ;; Be aware that `describe-buffer-bindings' puts its output into
      ;; the current buffer.
      (with-current-buffer (help-buffer)
	(describe-buffer-bindings buf prefix menus)))))

(defun where-is (definition &optional insert)
  "Print message listing key sequences that invoke the command DEFINITION.
Argument is a command definition, usually a symbol with a function definition.
If INSERT (the prefix arg) is non-nil, insert the message in the buffer."
  (interactive
   (let ((fn (function-called-at-point))
	 (enable-recursive-minibuffers t)
	 val)
     (setq val (completing-read
		(if fn
		    (format "Where is command (default %s): " fn)
		  "Where is command: ")
		obarray 'commandp t nil nil
		(and fn (symbol-name fn))))
     (list (unless (equal val "") (intern val))
	   current-prefix-arg)))
  (unless definition (error "No command"))
  (let ((func (indirect-function definition))
        (defs nil)
        (standard-output (if insert (current-buffer) standard-output)))
    ;; In DEFS, find all symbols that are aliases for DEFINITION.
    (mapatoms (lambda (symbol)
		(and (fboundp symbol)
		     (not (eq symbol definition))
		     (eq func (condition-case ()
				  (indirect-function symbol)
				(error symbol)))
		     (push symbol defs))))
    ;; Look at all the symbols--first DEFINITION,
    ;; then its aliases.
    (dolist (symbol (cons definition defs))
      (let* ((remapped (command-remapping symbol))
	     (keys (where-is-internal
		    symbol overriding-local-map nil nil remapped))
	     (keys (mapconcat 'key-description keys ", "))
	     string)
	(setq string
	      (if insert
		  (if (> (length keys) 0)
		      (if remapped
			  (format "%s (%s) (remapped from %s)"
				  keys remapped symbol)
			(format "%s (%s)" keys symbol))
		    (format "M-x %s RET" symbol))
		(if (> (length keys) 0)
		    (if remapped
			(format "%s is remapped to %s which is on %s"
				symbol remapped keys)
		      (format "%s is on %s" symbol keys))
		  ;; If this is the command the user asked about,
		  ;; and it is not on any key, say so.
		  ;; For other symbols, its aliases, say nothing
		  ;; about them unless they are on keys.
		  (if (eq symbol definition)
		      (format "%s is not on any key" symbol)))))
	(when string
	  (unless (eq symbol definition)
	    (princ ";\n its alias "))
	  (princ string)))))
  nil)

(defun help-key-description (key untranslated)
  (let ((string (key-description key)))
    (if (or (not untranslated)
	    (and (eq (aref untranslated 0) ?\e) (not (eq (aref key 0) ?\e))))
	string
      (let ((otherstring (key-description untranslated)))
	(if (equal string otherstring)
	    string
	  (format "%s (translated from %s)" string otherstring))))))

(defun describe-key-briefly (&optional key insert untranslated)
  "Print the name of the function KEY invokes.  KEY is a string.
If INSERT (the prefix arg) is non-nil, insert the message in the buffer.
If non-nil, UNTRANSLATED is a vector of the untranslated events.
It can also be a number in which case the untranslated events from
the last key hit are used.

If KEY is a menu item or a tool-bar button that is disabled, this command
temporarily enables it to allow getting help on disabled items and buttons."
  (interactive
   (let ((enable-disabled-menus-and-buttons t)
	 (cursor-in-echo-area t)
	 saved-yank-menu)
     (unwind-protect
	 (let (key)
	   ;; If yank-menu is empty, populate it temporarily, so that
	   ;; "Select and Paste" menu can generate a complete event.
	   (when (null (cdr yank-menu))
	     (setq saved-yank-menu (copy-sequence yank-menu))
	     (menu-bar-update-yank-menu "(any string)" nil))
           (while
               (progn
                 (setq key (read-key-sequence "Describe the following key, mouse click, or menu item: "))
                 (and (vectorp key)
                      (consp (aref key 0))
                      (symbolp (car (aref key 0)))
                      (string-match "\\(mouse\\|down\\|click\\|drag\\)"
                                    (symbol-name (car (aref key 0))))
                      (not (sit-for (/ double-click-time 1000.0) t)))))
	   ;; Clear the echo area message (Bug#7014).
	   (message nil)
	   ;; If KEY is a down-event, read and discard the
	   ;; corresponding up-event.  Note that there are also
	   ;; down-events on scroll bars and mode lines: the actual
	   ;; event then is in the second element of the vector.
	   (and (vectorp key)
		(let ((last-idx (1- (length key))))
		  (and (eventp (aref key last-idx))
		       (memq 'down (event-modifiers (aref key last-idx)))))
		(read-event))
	   (list
	    key
	    (if current-prefix-arg (prefix-numeric-value current-prefix-arg))
	    1))
       ;; Put yank-menu back as it was, if we changed it.
       (when saved-yank-menu
	 (setq yank-menu (copy-sequence saved-yank-menu))
	 (fset 'yank-menu (cons 'keymap yank-menu))))))
  (if (numberp untranslated)
      (setq untranslated (this-single-command-raw-keys)))
  (let* ((event (if (and (symbolp (aref key 0))
			 (> (length key) 1)
			 (consp (aref key 1)))
		    (aref key 1)
		  (aref key 0)))
	 (modifiers (event-modifiers event))
	 (standard-output (if insert (current-buffer) standard-output))
	 (mouse-msg (if (or (memq 'click modifiers) (memq 'down modifiers)
			    (memq 'drag modifiers)) " at that spot" ""))
	 (defn (key-binding key t))
	 key-desc)
    ;; Handle the case where we faked an entry in "Select and Paste" menu.
    (if (and (eq defn nil)
	     (stringp (aref key (1- (length key))))
	     (eq (key-binding (substring key 0 -1)) 'yank-menu))
	(setq defn 'menu-bar-select-yank))
    ;; Don't bother user with strings from (e.g.) the select-paste menu.
    (if (stringp (aref key (1- (length key))))
	(aset key (1- (length key)) "(any string)"))
    (if (and (> (length untranslated) 0)
	     (stringp (aref untranslated (1- (length untranslated)))))
	(aset untranslated (1- (length untranslated)) "(any string)"))
    ;; Now describe the key, perhaps as changed.
    (setq key-desc (help-key-description key untranslated))
    (if (or (null defn) (integerp defn) (equal defn 'undefined))
	(princ (format "%s%s is undefined" key-desc mouse-msg))
      (princ (format "%s%s runs the command %S" key-desc mouse-msg defn)))))

(defun help--key-binding-keymap (key &optional accept-default no-remap position)
  "Return a keymap holding a binding for KEY within current keymaps.
The effect of the arguments KEY, ACCEPT-DEFAULT, NO-REMAP and
POSITION is as documented in the function `key-binding'."
  (let* ((active-maps (current-active-maps t position))
         map found)
    ;; We loop over active maps like key-binding does.
    (while (and
            (not found)
            (setq map (pop active-maps)))
      (setq found (lookup-key map key accept-default))
      (when (integerp found)
        ;; The first `found' characters of KEY were found but not the
        ;; whole sequence.
        (setq found nil)))
    (when found
      (if (and (symbolp found)
               (not no-remap)
               (command-remapping found))
          ;; The user might want to know in which map the binding is
          ;; found, or in which map the remapping is found.  The
          ;; default is to show the latter.
          (help--key-binding-keymap (vector 'remap found))
        map))))

(defun help--binding-locus (key position)
  "Describe in which keymap KEY is defined.
Return a symbol pointing to that keymap if one exists ; otherwise
return nil.  The argument POSITION is as documented in the
function `key-binding'."
  (let ((map (help--key-binding-keymap key t nil position)))
    (when map
      (catch 'found
        (let ((advertised-syms (nconc
                                (list 'overriding-terminal-local-map
                                      'overriding-local-map)
                                (delq nil
                                      (mapcar
                                       (lambda (mode-and-map)
                                         (let ((mode (car mode-and-map)))
                                           (when (symbol-value mode)
                                             (intern-soft
                                              (format "%s-map" mode)))))
                                       minor-mode-map-alist))
                                (list 'global-map
                                      (intern-soft (format "%s-map" major-mode)))))
              found)
          ;; Look into these advertised symbols first.
          (dolist (sym advertised-syms)
            (when (and
                   (boundp sym)
                   (eq map (symbol-value sym)))
              (throw 'found sym)))
          ;; Only look in other symbols otherwise.
          (mapatoms
           (lambda (x)
             (when (and (boundp x)
                        ;; Avoid let-bound symbols.
                        (special-variable-p x)
                        (eq (symbol-value x) map))
               (throw 'found x))))
          nil)))))

(defun describe-key (&optional key untranslated up-event)
  "Display documentation of the function invoked by KEY.
KEY can be any kind of a key sequence; it can include keyboard events,
mouse events, and/or menu events.  When calling from a program,
pass KEY as a string or a vector.

If non-nil, UNTRANSLATED is a vector of the corresponding untranslated events.
It can also be a number, in which case the untranslated events from
the last key sequence entered are used.
UP-EVENT is the up-event that was discarded by reading KEY, or nil.

If KEY is a menu item or a tool-bar button that is disabled, this command
temporarily enables it to allow getting help on disabled items and buttons."
  (interactive
   (let ((enable-disabled-menus-and-buttons t)
	 (cursor-in-echo-area t)
	 saved-yank-menu)
     (unwind-protect
	 (let (key)
	   ;; If yank-menu is empty, populate it temporarily, so that
	   ;; "Select and Paste" menu can generate a complete event.
	   (when (null (cdr yank-menu))
	     (setq saved-yank-menu (copy-sequence yank-menu))
	     (menu-bar-update-yank-menu "(any string)" nil))
           (while
               (progn
                 (setq key (read-key-sequence "Describe the following key, mouse click, or menu item: "))
                 (and (vectorp key)
                      (consp (aref key 0))
                      (symbolp (car (aref key 0)))
                      (string-match "\\(mouse\\|down\\|click\\|drag\\)"
                                    (symbol-name (car (aref key 0))))
                      (not (sit-for (/ double-click-time 1000.0) t)))))
	   (list
	    key
	    (prefix-numeric-value current-prefix-arg)
	    ;; If KEY is a down-event, read and include the
	    ;; corresponding up-event.  Note that there are also
	    ;; down-events on scroll bars and mode lines: the actual
	    ;; event then is in the second element of the vector.
	    (and (vectorp key)
		 (let ((last-idx (1- (length key))))
		   (and (eventp (aref key last-idx))
			(memq 'down (event-modifiers (aref key last-idx)))))
		 (or (and (eventp (aref key 0))
			  (memq 'down (event-modifiers (aref key 0)))
			  ;; However, for the C-down-mouse-2 popup
			  ;; menu, there is no subsequent up-event.  In
			  ;; this case, the up-event is the next
			  ;; element in the supplied vector.
			  (= (length key) 1))
		     (and (> (length key) 1)
			  (eventp (aref key 1))
			  (memq 'down (event-modifiers (aref key 1)))))
		 (read-event))))
       ;; Put yank-menu back as it was, if we changed it.
       (when saved-yank-menu
	 (setq yank-menu (copy-sequence saved-yank-menu))
	 (fset 'yank-menu (cons 'keymap yank-menu))))))
  (if (numberp untranslated)
      (setq untranslated (this-single-command-raw-keys)))
  (let* ((event (aref key (if (and (symbolp (aref key 0))
				   (> (length key) 1)
				   (consp (aref key 1)))
			      1
			    0)))
	 (modifiers (event-modifiers event))
	 (mouse-msg (if (or (memq 'click modifiers) (memq 'down modifiers)
			    (memq 'drag modifiers)) " at that spot" ""))
	 (defn (key-binding key t))
         key-locus key-locus-up key-locus-up-tricky
	 defn-up defn-up-tricky ev-type
	 mouse-1-remapped mouse-1-tricky)

    ;; Handle the case where we faked an entry in "Select and Paste" menu.
    (when (and (eq defn nil)
	       (stringp (aref key (1- (length key))))
	       (eq (key-binding (substring key 0 -1)) 'yank-menu))
      (setq defn 'menu-bar-select-yank))
    (if (or (null defn) (integerp defn) (equal defn 'undefined))
	(message "%s%s is undefined"
		 (help-key-description key untranslated) mouse-msg)
      (help-setup-xref (list #'describe-function defn)
		       (called-interactively-p 'interactive))
      ;; Don't bother user with strings from (e.g.) the select-paste menu.
      (when (stringp (aref key (1- (length key))))
	(aset key (1- (length key)) "(any string)"))
      (when (and untranslated
		 (stringp (aref untranslated (1- (length untranslated)))))
	(aset untranslated (1- (length untranslated))
	      "(any string)"))
      ;; Need to do this before erasing *Help* buffer in case event
      ;; is a mouse click in an existing *Help* buffer.
      (when up-event
	(setq ev-type (event-basic-type up-event))
	(let ((sequence (vector up-event)))
	  (when (and (eq ev-type 'mouse-1)
		     mouse-1-click-follows-link
		     (not (eq mouse-1-click-follows-link 'double))
		     (setq mouse-1-remapped
			   (mouse-on-link-p (event-start up-event))))
	    (setq mouse-1-tricky (and (integerp mouse-1-click-follows-link)
				      (> mouse-1-click-follows-link 0)))
	    (cond ((stringp mouse-1-remapped)
		   (setq sequence mouse-1-remapped))
		  ((vectorp mouse-1-remapped)
		   (setcar up-event (elt mouse-1-remapped 0)))
		  (t (setcar up-event 'mouse-2))))
	  (setq defn-up (key-binding sequence nil nil (event-start up-event)))
          (setq key-locus-up (help--binding-locus sequence (event-start up-event)))
	  (when mouse-1-tricky
	    (setq sequence (vector up-event))
	    (aset sequence 0 'mouse-1)
	    (setq defn-up-tricky (key-binding sequence nil nil (event-start up-event)))
            (setq key-locus-up-tricky (help--binding-locus sequence (event-start up-event))))))
      (setq key-locus (help--binding-locus key (event-start event)))
      (with-help-window (help-buffer)
	(princ (help-key-description key untranslated))
	(princ (format "%s runs the command %S%s, which is "
		       mouse-msg defn (if key-locus
                                          (format " (found in %s)" key-locus)
                                        "")))
	(describe-function-1 defn)
	(when up-event
	  (unless (or (null defn-up)
		      (integerp defn-up)
		      (equal defn-up 'undefined))
	    (princ (format "

----------------- up-event %s----------------

%s%s%s runs the command %S%s, which is "
			   (if mouse-1-tricky "(short click) " "")
			   (key-description (vector up-event))
			   mouse-msg
			   (if mouse-1-remapped
                               " is remapped to <mouse-2>, which" "")
			   defn-up (if key-locus-up
                                       (format " (found in %s)" key-locus-up)
                                     "")))
	    (describe-function-1 defn-up))
	  (unless (or (null defn-up-tricky)
		      (integerp defn-up-tricky)
		      (eq defn-up-tricky 'undefined))
	    (princ (format "

----------------- up-event (long click) ----------------

Pressing <%S>%s for longer than %d milli-seconds
runs the command %S%s, which is "
			   ev-type mouse-msg
			   mouse-1-click-follows-link
			   defn-up-tricky (if key-locus-up-tricky
                                              (format " (found in %s)" key-locus-up-tricky)
                                            "")))
	    (describe-function-1 defn-up-tricky)))))))

(defun describe-mode (&optional buffer)
  "Display documentation of current major mode and minor modes.
A brief summary of the minor modes comes first, followed by the
major mode description.  This is followed by detailed
descriptions of the minor modes, each on a separate page.

For this to work correctly for a minor mode, the mode's indicator
variable \(listed in `minor-mode-alist') must also be a function
whose documentation describes the minor mode.

If called from Lisp with a non-nil BUFFER argument, display
documentation for the major and minor modes of that buffer."
  (interactive "@")
  (unless buffer (setq buffer (current-buffer)))
  (help-setup-xref (list #'describe-mode buffer)
		   (called-interactively-p 'interactive))
  ;; For the sake of help-do-xref and help-xref-go-back,
  ;; don't switch buffers before calling `help-buffer'.
  (with-help-window (help-buffer)
    (with-current-buffer buffer
      (let (minor-modes)
	;; Older packages do not register in minor-mode-list but only in
	;; minor-mode-alist.
	(dolist (x minor-mode-alist)
	  (setq x (car x))
	  (unless (memq x minor-mode-list)
	    (push x minor-mode-list)))
	;; Find enabled minor mode we will want to mention.
	(dolist (mode minor-mode-list)
	  ;; Document a minor mode if it is listed in minor-mode-alist,
	  ;; non-nil, and has a function definition.
	  (let ((fmode (or (get mode :minor-mode-function) mode)))
	    (and (boundp mode) (symbol-value mode)
		 (fboundp fmode)
		 (let ((pretty-minor-mode
			(if (string-match "\\(\\(-minor\\)?-mode\\)?\\'"
					  (symbol-name fmode))
			    (capitalize
			     (substring (symbol-name fmode)
					0 (match-beginning 0)))
			  fmode)))
		   (push (list fmode pretty-minor-mode
			       (format-mode-line (assq mode minor-mode-alist)))
			 minor-modes)))))
	(setq minor-modes
	      (sort minor-modes
		    (lambda (a b) (string-lessp (cadr a) (cadr b)))))
	(when minor-modes
	  (princ "Enabled minor modes:\n")
	  (make-local-variable 'help-button-cache)
	  (with-current-buffer standard-output
	    (dolist (mode minor-modes)
	      (let ((mode-function (nth 0 mode))
		    (pretty-minor-mode (nth 1 mode))
		    (indicator (nth 2 mode)))
		(save-excursion
		  (goto-char (point-max))
		  (princ "\n\f\n")
		  (push (point-marker) help-button-cache)
		  ;; Document the minor modes fully.
                  (insert-text-button
                   pretty-minor-mode 'type 'help-function
                   'help-args (list mode-function)
                   'button '(t))
		  (princ (format " minor mode (%s):\n"
				 (if (zerop (length indicator))
				     "no indicator"
				   (format "indicator%s"
					   indicator))))
		  (princ (documentation mode-function)))
		(insert-button pretty-minor-mode
			       'action (car help-button-cache)
			       'follow-link t
			       'help-echo "mouse-2, RET: show full information")
		(newline)))
	    (forward-line -1)
	    (fill-paragraph nil)
	    (forward-line 1))

	  (princ "\n(Information about these minor modes follows the major mode info.)\n\n"))
	;; Document the major mode.
	(let ((mode mode-name))
	  (with-current-buffer standard-output
            (let ((start (point)))
              (insert (format-mode-line mode nil nil buffer))
              (add-text-properties start (point) '(face bold)))))
	(princ " mode")
	(let* ((mode major-mode)
	       (file-name (find-lisp-object-file-name mode nil)))
	  (when file-name
	    (princ (format-message " defined in `%s'"
                                   (file-name-nondirectory file-name)))
	    ;; Make a hyperlink to the library.
	    (with-current-buffer standard-output
	      (save-excursion
		(re-search-backward (substitute-command-keys "`\\([^`']+\\)'")
                                    nil t)
		(help-xref-button 1 'help-function-def mode file-name)))))
	(princ ":\n")
	(princ (documentation major-mode)))))
  ;; For the sake of IELM and maybe others
  nil)


(defun describe-minor-mode (minor-mode)
  "Display documentation of a minor mode given as MINOR-MODE.
MINOR-MODE can be a minor mode symbol or a minor mode indicator string
appeared on the mode-line."
  (interactive (list (completing-read
		      "Minor mode: "
			      (nconc
			       (describe-minor-mode-completion-table-for-symbol)
			       (describe-minor-mode-completion-table-for-indicator)
			       ))))
  (if (symbolp minor-mode)
      (setq minor-mode (symbol-name minor-mode)))
  (let ((symbols (describe-minor-mode-completion-table-for-symbol))
	(indicators (describe-minor-mode-completion-table-for-indicator)))
    (cond
     ((member minor-mode symbols)
      (describe-minor-mode-from-symbol (intern minor-mode)))
     ((member minor-mode indicators)
      (describe-minor-mode-from-indicator minor-mode))
     (t
      (error "No such minor mode: %s" minor-mode)))))

;; symbol
(defun describe-minor-mode-completion-table-for-symbol ()
  ;; In order to list up all minor modes, minor-mode-list
  ;; is used here instead of minor-mode-alist.
  (delq nil (mapcar 'symbol-name minor-mode-list)))

(defun describe-minor-mode-from-symbol (symbol)
  "Display documentation of a minor mode given as a symbol, SYMBOL"
  (interactive (list (intern (completing-read
			      "Minor mode symbol: "
			      (describe-minor-mode-completion-table-for-symbol)))))
  (if (fboundp symbol)
      (describe-function symbol)
    (describe-variable symbol)))

;; indicator
(defun describe-minor-mode-completion-table-for-indicator ()
  (delq nil
	(mapcar (lambda (x)
		  (let ((i (format-mode-line x)))
		    ;; remove first space if existed
		    (cond
		     ((= 0 (length i))
		      nil)
		     ((eq (aref i 0) ?\s)
		      (substring i 1))
		     (t
		      i))))
		minor-mode-alist)))

(defun describe-minor-mode-from-indicator (indicator)
  "Display documentation of a minor mode specified by INDICATOR.
If you call this function interactively, you can give indicator which
is currently activated with completion."
  (interactive (list
		(completing-read
		 "Minor mode indicator: "
		 (describe-minor-mode-completion-table-for-indicator))))
  (let ((minor-mode (lookup-minor-mode-from-indicator indicator)))
    (if minor-mode
	(describe-minor-mode-from-symbol minor-mode)
      (error "Cannot find minor mode for `%s'" indicator))))

(defun lookup-minor-mode-from-indicator (indicator)
  "Return a minor mode symbol from its indicator on the mode line."
  ;; remove first space if existed
  (if (and (< 0 (length indicator))
	   (eq (aref indicator 0) ?\s))
      (setq indicator (substring indicator 1)))
  (let ((minor-modes minor-mode-alist)
	result)
    (while minor-modes
      (let* ((minor-mode (car (car minor-modes)))
	     (anindicator (format-mode-line
			   (car (cdr (car minor-modes))))))
	;; remove first space if existed
	(if (and (stringp anindicator)
		 (> (length anindicator) 0)
		 (eq (aref anindicator 0) ?\s))
	    (setq anindicator (substring anindicator 1)))
	(if (equal indicator anindicator)
	    (setq result minor-mode
		  minor-modes nil)
	  (setq minor-modes (cdr minor-modes)))))
    result))

;;; Automatic resizing of temporary buffers.
(defcustom temp-buffer-max-height
  (lambda (buffer)
    (if (and (display-graphic-p) (eq (selected-window) (frame-root-window)))
	(/ (x-display-pixel-height) (frame-char-height) 2)
      (/ (- (frame-height) 2) 2)))
  "Maximum height of a window displaying a temporary buffer.
This is effective only when Temp Buffer Resize mode is enabled.
The value is the maximum height (in lines) which
`resize-temp-buffer-window' will give to a window displaying a
temporary buffer.  It can also be a function to be called to
choose the height for such a buffer.  It gets one argument, the
buffer, and should return a positive integer.  At the time the
function is called, the window to be resized is selected."
  :type '(choice integer function)
  :group 'help
  :version "24.3")

(defcustom temp-buffer-max-width
  (lambda (buffer)
    (if (and (display-graphic-p) (eq (selected-window) (frame-root-window)))
	(/ (x-display-pixel-width) (frame-char-width) 2)
      (/ (- (frame-width) 2) 2)))
  "Maximum width of a window displaying a temporary buffer.
This is effective only when Temp Buffer Resize mode is enabled.
The value is the maximum width (in columns) which
`resize-temp-buffer-window' will give to a window displaying a
temporary buffer.  It can also be a function to be called to
choose the width for such a buffer.  It gets one argument, the
buffer, and should return a positive integer.  At the time the
function is called, the window to be resized is selected."
  :type '(choice integer function)
  :group 'help
  :version "24.4")

(define-minor-mode temp-buffer-resize-mode
  "Toggle auto-resizing temporary buffer windows (Temp Buffer Resize Mode).
With a prefix argument ARG, enable Temp Buffer Resize mode if ARG
is positive, and disable it otherwise.  If called from Lisp,
enable the mode if ARG is omitted or nil.

When Temp Buffer Resize mode is enabled, the windows in which we
show a temporary buffer are automatically resized in height to
fit the buffer's contents, but never more than
`temp-buffer-max-height' nor less than `window-min-height'.

A window is resized only if it has been specially created for the
buffer.  Windows that have shown another buffer before are not
resized.  A frame is resized only if `fit-frame-to-buffer' is
non-nil.

This mode is used by `help', `apropos' and `completion' buffers,
and some others."
  :global t :group 'help
  (if temp-buffer-resize-mode
      ;; `help-make-xrefs' may add a `back' button and thus increase the
      ;; text size, so `resize-temp-buffer-window' must be run *after* it.
      (add-hook 'temp-buffer-show-hook 'resize-temp-buffer-window 'append)
    (remove-hook 'temp-buffer-show-hook 'resize-temp-buffer-window)))

(defun resize-temp-buffer-window (&optional window)
  "Resize WINDOW to fit its contents.
WINDOW must be a live window and defaults to the selected one.
Do not resize if WINDOW was not created by `display-buffer'.

If WINDOW is part of a vertical combination, restrain its new
size by `temp-buffer-max-height' and do not resize if its minimum
accessible position is scrolled out of view.  If WINDOW is part
of a horizontal combination, restrain its new size by
`temp-buffer-max-width'.  In both cases, the value of the option
`fit-window-to-buffer-horizontally' can inhibit resizing.

If WINDOW is the root window of its frame, resize the frame
provided `fit-frame-to-buffer' is non-nil.

This function may call `preserve-window-size' to preserve the
size of WINDOW."
  (setq window (window-normalize-window window t))
  (let ((height (if (functionp temp-buffer-max-height)
		    (with-selected-window window
		      (funcall temp-buffer-max-height (window-buffer)))
		  temp-buffer-max-height))
	(width (if (functionp temp-buffer-max-width)
		   (with-selected-window window
		     (funcall temp-buffer-max-width (window-buffer)))
		 temp-buffer-max-width))
	(quit-cadr (cadr (window-parameter window 'quit-restore))))
    ;; Resize WINDOW iff it was made by `display-buffer'.
    (when (or (and (eq quit-cadr 'window)
		   (or (and (window-combined-p window)
			    (not (eq fit-window-to-buffer-horizontally
				     'only))
			    (pos-visible-in-window-p (point-min) window))
		       (and (window-combined-p window t)
			    fit-window-to-buffer-horizontally)))
	      (and (eq quit-cadr 'frame)
                   fit-frame-to-buffer
                   (eq window (frame-root-window window))))
	(fit-window-to-buffer window height nil width nil t))))

;;; Help windows.
(defcustom help-window-select nil
  "Non-nil means select help window for viewing.
Choices are:

 never (nil) Select help window only if there is no other window
             on its frame.

 other       Select help window if and only if it appears on the
             previously selected frame, that frame contains at
             least two other windows and the help window is
             either new or showed a different buffer before.

 always (t)  Always select the help window.

If this option is non-nil and the help window appears on another
frame, then give that frame input focus too.  Note also that if
the help window appears on another frame, it may get selected and
its frame get input focus even if this option is nil.

This option has effect if and only if the help window was created
by `with-help-window'."
  :type '(choice (const :tag "never (nil)" nil)
		 (const :tag "other" other)
		 (const :tag "always (t)" t))
  :group 'help
  :version "23.1")

(defcustom help-enable-auto-load t
  "Whether Help commands can perform autoloading.
If non-nil, whenever \\[describe-function] is called for an
autoloaded function whose docstring contains any key substitution
construct (see `substitute-command-keys'), the library is loaded,
so that the documentation can show the right key bindings."
  :type 'boolean
  :group 'help
  :version "24.3")

(defun help-window-display-message (quit-part window &optional scroll)
  "Display message telling how to quit and scroll help window.
QUIT-PART is a string telling how to quit the help window WINDOW.
Optional argument SCROLL non-nil means tell how to scroll WINDOW.
SCROLL equal `other' means tell how to scroll the \"other\"
window."
  (let ((scroll-part
	 (cond
	  ;; If we don't have QUIT-PART we probably reuse a window
	  ;; showing the same buffer so we don't show any message.
	  ((not quit-part) nil)
	  ((pos-visible-in-window-p
	    (with-current-buffer (window-buffer window)
	      (point-max)) window t)
	   ;; Buffer end is at least partially visible, no need to talk
	   ;; about scrolling.
	   ".")
	  ((eq scroll 'other)
	   ", \\[scroll-other-window] to scroll help.")
	  (scroll ", \\[scroll-up] to scroll help."))))
    (message "%s"
     (substitute-command-keys (concat quit-part scroll-part)))))

(defun help-window-setup (window &optional value)
  "Set up help window WINDOW for `with-help-window'.
WINDOW is the window used for displaying the help buffer.
Return VALUE."
  (let* ((help-buffer (when (window-live-p window)
			(window-buffer window)))
	 (help-setup (when (window-live-p window)
		       (car (window-parameter window 'quit-restore))))
	 (frame (window-frame window)))

    (when help-buffer
      ;; Handle `help-window-point-marker'.
      (when (eq (marker-buffer help-window-point-marker) help-buffer)
	(set-window-point window help-window-point-marker)
	;; Reset `help-window-point-marker'.
	(set-marker help-window-point-marker nil))

      ;; If the help window appears on another frame, select it if
      ;; `help-window-select' is non-nil and give that frame input focus
      ;; too.  See also Bug#19012.
      (when (and help-window-select
		 (frame-live-p help-window-old-frame)
		 (not (eq frame help-window-old-frame)))
	(select-window window)
	(select-frame-set-input-focus frame))

      (cond
       ((or (eq window (selected-window))
	    ;; If the help window is on the selected frame, select
	    ;; it if `help-window-select' is t or `help-window-select'
	    ;; is 'other, the frame contains at least three windows, and
	    ;; the help window did show another buffer before.  See also
	    ;; Bug#11039.
	    (and (eq frame (selected-frame))
		 (or (eq help-window-select t)
		     (and (eq help-window-select 'other)
			  (> (length (window-list nil 'no-mini)) 2)
			  (not (eq help-setup 'same))))
		 (select-window window)))
	;; The help window is or gets selected ...
	(help-window-display-message
	 (cond
	  ((eq help-setup 'window)
	   ;; ... and is new, ...
	   "Type \"q\" to delete help window")
	  ((eq help-setup 'frame)
	   ;; ... on a new frame, ...
	   "Type \"q\" to quit the help frame")
	  ((eq help-setup 'other)
	   ;; ... or displayed some other buffer before.
	   "Type \"q\" to restore previous buffer"))
	 window t))
       ((and (eq (window-frame window) help-window-old-frame)
	     (= (length (window-list nil 'no-mini)) 2))
	;; There are two windows on the help window's frame and the
	;; other one is the selected one.
	(help-window-display-message
	 (cond
	  ((eq help-setup 'window)
	   "Type \\[delete-other-windows] to delete the help window")
	  ((eq help-setup 'other)
	   "Type \"q\" in help window to restore its previous buffer"))
	 window 'other))
       (t
	;; The help window is not selected ...
	(help-window-display-message
	 (cond
	  ((eq help-setup 'window)
	   ;; ... and is new, ...
	   "Type \"q\" in help window to delete it")
	  ((eq help-setup 'other)
	   ;; ... or displayed some other buffer before.
	   "Type \"q\" in help window to restore previous buffer"))
	 window))))
    ;; Return VALUE.
    value))

;; `with-help-window' is a wrapper for `with-temp-buffer-window'
;; providing the following additional twists:

;; (1) It puts the buffer in `help-mode' (via `help-mode-setup') and
;;     adds cross references (via `help-mode-finish').

;; (2) It issues a message telling how to scroll and quit the help
;;     window (via `help-window-setup').

;; (3) An option (customizable via `help-window-select') to select the
;;     help window automatically.

;; (4) A marker (`help-window-point-marker') to move point in the help
;;     window to an arbitrary buffer position.
(defmacro with-help-window (buffer-name &rest body)
  "Display buffer named BUFFER-NAME in a help window.
Evaluate the forms in BODY with standard output bound to a buffer
called BUFFER-NAME (creating it if it does not exist), put that
buffer in `help-mode', display the buffer in a window (see
`with-temp-buffer-window' for details) and issue a message how to
deal with that \"help\" window when it's no more needed.  Select
the help window if the current value of the user option
`help-window-select' says so.  Return last value in BODY."
  (declare (indent 1) (debug t))
  `(progn
     ;; Make `help-window-point-marker' point nowhere.  The only place
     ;; where this should be set to a buffer position is within BODY.
     (set-marker help-window-point-marker nil)
     (let ((temp-buffer-window-setup-hook
	    (cons 'help-mode-setup temp-buffer-window-setup-hook))
	   (temp-buffer-window-show-hook
	    (cons 'help-mode-finish temp-buffer-window-show-hook)))
       (setq help-window-old-frame (selected-frame))
       (with-temp-buffer-window
	,buffer-name nil 'help-window-setup (progn ,@body)))))

;; Called from C, on encountering `help-char' when reading a char.
;; Don't print to *Help*; that would clobber Help history.
(defun help-form-show ()
  "Display the output of a non-nil `help-form'."
  (let ((msg (eval help-form)))
    (if (stringp msg)
	(with-output-to-temp-buffer " *Char Help*"
	  (princ msg)))))


(defun help--docstring-quote (string)
  "Return a doc string that represents STRING.
The result, when formatted by `substitute-command-keys', should equal STRING."
  (replace-regexp-in-string "['\\`‘’]" "\\\\=\\&" string))

;; The following functions used to be in help-fns.el, which is not preloaded.
;; But for various reasons, they are more widely needed, so they were
;; moved to this file, which is preloaded.  http://debbugs.gnu.org/17001

(defun help-split-fundoc (docstring def)
  "Split a function DOCSTRING into the actual doc and the usage info.
Return (USAGE . DOC) or nil if there's no usage info, where USAGE info
is a string describing the argument list of DEF, such as
\"(apply FUNCTION &rest ARGUMENTS)\".
DEF is the function whose usage we're looking for in DOCSTRING."
  ;; Functions can get the calling sequence at the end of the doc string.
  ;; In cases where `function' has been fset to a subr we can't search for
  ;; function's name in the doc string so we use `fn' as the anonymous
  ;; function name instead.
  (when (and docstring (string-match "\n\n(fn\\(\\( .*\\)?)\\)\\'" docstring))
    (let ((doc (unless (zerop (match-beginning 0))
		 (substring docstring 0 (match-beginning 0))))
	  (usage-tail (match-string 1 docstring)))
      (cons (format "(%s%s"
		    ;; Replace `fn' with the actual function name.
		    (if (symbolp def)
			(help--docstring-quote (format "%S" def))
		      'anonymous)
		    usage-tail)
	    doc))))

(defun help-add-fundoc-usage (docstring arglist)
  "Add the usage info to DOCSTRING.
If DOCSTRING already has a usage info, then just return it unchanged.
The usage info is built from ARGLIST.  DOCSTRING can be nil.
ARGLIST can also be t or a string of the form \"(FUN ARG1 ARG2 ...)\"."
  (unless (stringp docstring) (setq docstring ""))
  (if (or (string-match "\n\n(fn\\(\\( .*\\)?)\\)\\'" docstring)
          (eq arglist t))
      docstring
    (concat docstring
	    (if (string-match "\n?\n\\'" docstring)
		(if (< (- (match-end 0) (match-beginning 0)) 2) "\n" "")
	      "\n\n")
	    (if (stringp arglist)
                (if (string-match "\\`[^ ]+\\(.*\\))\\'" arglist)
                    (concat "(fn" (match-string 1 arglist) ")")
                  (error "Unrecognized usage format"))
	      (help--make-usage-docstring 'fn arglist)))))

(defun help-function-arglist (def &optional preserve-names)
  "Return a formal argument list for the function DEF.
IF PRESERVE-NAMES is non-nil, return a formal arglist that uses
the same names as used in the original source code, when possible."
  ;; Handle symbols aliased to other symbols.
  (if (and (symbolp def) (fboundp def)) (setq def (indirect-function def)))
  ;; If definition is a macro, find the function inside it.
  (if (eq (car-safe def) 'macro) (setq def (cdr def)))
  (cond
   ((and (byte-code-function-p def) (listp (aref def 0))) (aref def 0))
   ((eq (car-safe def) 'lambda) (nth 1 def))
   ((eq (car-safe def) 'closure) (nth 2 def))
   ((or (and (byte-code-function-p def) (integerp (aref def 0)))
        (subrp def))
    (or (when preserve-names
          (let* ((doc (condition-case nil (documentation def) (error nil)))
                 (docargs (if doc (car (help-split-fundoc doc nil))))
                 (arglist (if docargs
                              (cdar (read-from-string (downcase docargs)))))
                 (valid t))
            ;; Check validity.
            (dolist (arg arglist)
              (unless (and (symbolp arg)
                           (let ((name (symbol-name arg)))
                             (if (eq (aref name 0) ?&)
                                 (memq arg '(&rest &optional))
                               (not (string-match "\\." name)))))
                (setq valid nil)))
            (when valid arglist)))
        (let* ((args-desc (if (not (subrp def))
                              (aref def 0)
                            (let ((a (subr-arity def)))
                              (logior (car a)
                                      (if (numberp (cdr a))
                                          (lsh (cdr a) 8)
                                        (lsh 1 7))))))
               (max (lsh args-desc -8))
               (min (logand args-desc 127))
               (rest (logand args-desc 128))
               (arglist ()))
          (dotimes (i min)
            (push (intern (concat "arg" (number-to-string (1+ i)))) arglist))
          (when (> max min)
            (push '&optional arglist)
            (dotimes (i (- max min))
              (push (intern (concat "arg" (number-to-string (+ 1 i min))))
                    arglist)))
          (unless (zerop rest) (push '&rest arglist) (push 'rest arglist))
          (nreverse arglist))))
   ((and (autoloadp def) (not (eq (nth 4 def) 'keymap)))
    "[Arg list not available until function definition is loaded.]")
   (t t)))

(defun help--make-usage (function arglist)
  (cons (if (symbolp function) function 'anonymous)
	(mapcar (lambda (arg)
		  (if (not (symbolp arg)) arg
		    (let ((name (symbol-name arg)))
		      (cond
                       ((string-match "\\`&" name) arg)
                       ((string-match "\\`_." name)
                        (intern (upcase (substring name 1))))
                       (t (intern (upcase name)))))))
		arglist)))

(define-obsolete-function-alias 'help-make-usage 'help--make-usage "25.1")

(defun help--make-usage-docstring (fn arglist)
  (let ((print-escape-newlines t))
    (help--docstring-quote (format "%S" (help--make-usage fn arglist)))))


(provide 'help)

;;; help.el ends here