summaryrefslogtreecommitdiff
path: root/lisp/ehelp.el
blob: 66e4f5c633bf7f4d0b14f3162efc4e27f41c1185 (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
;;; ehelp.el --- bindings for electric-help mode -*- lexical-binding: t -*-

;; Copyright (C) 1986, 1995, 2000-2015 Free Software Foundation, Inc.

;; Author: Richard Mlynarik
;; (according to ack.texi and authors.el)
;; Maintainer: emacs-devel@gnu.org
;; Keywords: help, extensions

;; 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 package provides a pre-packaged `Electric Help Mode' for
;; browsing Emacs help screens.  There is one entry point,
;; `with-electric-help'; all you have to give it is a no-argument
;; function that generates the actual text of the help into the current
;; buffer.

;; To make this the default, you must do
;; (require 'ehelp)
;; (define-key global-map "\C-h" 'ehelp-command)
;; (define-key global-map [help] 'ehelp-command)
;; (define-key global-map [f1] 'ehelp-command)

;;; Code:

(require 'electric)

(defvar electric-help-form-to-execute nil)

(defgroup electric-help ()
  "Electric help facility."
  :version "21.1"
  :group 'help)

(defcustom electric-help-shrink-window t
  "If set, adjust help window sizes to buffer sizes when displaying help."
  :type 'boolean
  :group 'electric-help)

(defcustom electric-help-mode-hook nil
  "Hook run by `with-electric-help' after initializing the buffer."
  :type 'hook
  :group 'electric-help)

(put 'electric-help-undefined 'suppress-keymap t)

(defvar electric-help-map
  (let ((map (make-keymap)))
    ;; FIXME fragile.  Should derive from help-mode-map in a smarter way.
    (set-keymap-parent map button-buffer-map)
    ;; allow all non-self-inserting keys - search, scroll, etc, but
    ;; let M-x and C-x exit ehelp mode and retain buffer:
    (suppress-keymap map)
    (define-key map "\C-u" 'electric-help-undefined)
    (define-key map [?\C-0] 'electric-help-undefined)
    (define-key map [?\C-1] 'electric-help-undefined)
    (define-key map [?\C-2] 'electric-help-undefined)
    (define-key map [?\C-3] 'electric-help-undefined)
    (define-key map [?\C-4] 'electric-help-undefined)
    (define-key map [?\C-5] 'electric-help-undefined)
    (define-key map [?\C-6] 'electric-help-undefined)
    (define-key map [?\C-7] 'electric-help-undefined)
    (define-key map [?\C-8] 'electric-help-undefined)
    (define-key map [?\C-9] 'electric-help-undefined)
    (define-key map (char-to-string help-char) 'electric-help-help)
    (define-key map "?" 'electric-help-help)
    (define-key map " " 'scroll-up)
    (define-key map [?\S-\ ] 'scroll-down)
    (define-key map "\^?" 'scroll-down)
    (define-key map "." 'beginning-of-buffer)
    (define-key map "<" 'beginning-of-buffer)
    (define-key map ">" 'end-of-buffer)
    ;(define-key map "\C-g" 'electric-help-exit)
    (define-key map "Q" 'electric-help-exit)
    (define-key map "q" 'electric-help-exit)
    ;;a better key than this?
    (define-key map "R" 'electric-help-retain)
    (define-key map "r" 'electric-help-retain)
    (define-key map "\ex" 'electric-help-execute-extended)
    (define-key map "\C-x" 'electric-help-ctrl-x-prefix)
    map)
  "Keymap defining commands available in `electric-help-mode'.")

(defvar electric-help-orig-major-mode nil)
(make-variable-buffer-local 'electric-help-orig-major-mode)

(defun electric-help-mode ()
  "`with-electric-help' temporarily places its buffer in this mode.
\(On exit from `with-electric-help', the original `major-mode' is restored.)"
  (setq buffer-read-only t)
  (setq electric-help-orig-major-mode major-mode)
  (setq mode-name "Help")
  (setq major-mode 'help-mode)
  (setq mode-line-buffer-identification '(" Help:  %b"))
  (use-local-map electric-help-map)
  (add-hook 'mouse-leave-buffer-hook 'electric-help-retain)
  (view-mode -1)
  ;; this is done below in with-electric-help
  ;(run-hooks 'electric-help-mode-hook)
  )

;;;###autoload
(defun with-electric-help (thunk &optional buffer noerase minheight)
  "Pop up an \"electric\" help buffer.
THUNK is a function of no arguments which is called to initialize the
contents of BUFFER.  BUFFER defaults to `*Help*'.  BUFFER will be
erased before THUNK is called unless NOERASE is non-nil.  THUNK will
be called while BUFFER is current and with `standard-output' bound to
the buffer specified by BUFFER.

If THUNK returns nil, we display BUFFER starting at the top, and shrink
the window to fit.  If THUNK returns non-nil, we don't do those things.

After THUNK has been called, this function \"electrically\" pops up a
window in which BUFFER is displayed and allows the user to scroll
through that buffer in `electric-help-mode'.  The window's height will
be at least MINHEIGHT if this value is non-nil.

If THUNK returns nil, we display BUFFER starting at the top, and
shrink the window to fit if `electric-help-shrink-window' is non-nil.
If THUNK returns non-nil, we don't do those things.

When the user exits (with `electric-help-exit', or otherwise), the help
buffer's window disappears (i.e., we use `save-window-excursion'), and
BUFFER is put back into its original major mode."
  (setq buffer (get-buffer-create (or buffer "*Help*")))
  (let ((one (one-window-p t))
	(config (current-window-configuration))
        (bury nil)
        (electric-help-form-to-execute nil))
    (unwind-protect
         (save-excursion
           (when one
	     (goto-char (window-start)))
           (let ((pop-up-windows t))
             (pop-to-buffer buffer))
           (with-current-buffer buffer
             (when (and minheight (< (window-height) minheight))
	       (enlarge-window (- minheight (window-height))))
             (electric-help-mode)
	     (setq buffer-read-only nil)
	     (unless noerase
	       (erase-buffer)))
           (let ((standard-output buffer))
             (unless (funcall thunk)
	       (set-buffer buffer)
	       (set-buffer-modified-p nil)
	       (goto-char (point-min))
	       (when (and one electric-help-shrink-window)
		 (shrink-window-if-larger-than-buffer))))
           (set-buffer buffer)
           (run-hooks 'electric-help-mode-hook)
	   (setq buffer-read-only t)
           (if (eq (car-safe (electric-help-command-loop)) 'retain)
               (setq config (current-window-configuration))
	     (setq bury t))
	   ;; Remove the hook.
	   (when (memq 'electric-help-retain mouse-leave-buffer-hook)
	     (remove-hook 'mouse-leave-buffer-hook 'electric-help-retain)))
      (message "")
      (set-buffer buffer)
      (setq buffer-read-only nil)

      ;; Restore the original major mode saved by `electric-help-mode'.
      ;; We should really get a usable *Help* buffer when retaining
      ;; the electric one with `r'.  The problem is that a simple
      ;; call to `help-mode' won't cut it; e.g. RET is bound wrong
      ;; afterwards (`View-scroll-line-forward' instead of `help-follow').
      ;; That's because Help mode should be set with `with-help-window'
      ;; instead of the direct call to `help-mode'. But at least
      ;; RET works correctly on links after using `help-mode'.
      ;; This is satisfactory enough.
      (condition-case ()
          (funcall (or electric-help-orig-major-mode 'fundamental-mode))
        (error nil))

      (set-window-configuration config)
      (when bury
	;;>> Perhaps this shouldn't be done,
	;; so that when we say "Press space to bury" we mean it
	(replace-buffer-in-windows buffer)
	;; must do this outside of save-window-excursion
	(bury-buffer buffer))
      (if (functionp electric-help-form-to-execute)
          (funcall electric-help-form-to-execute)
        (eval electric-help-form-to-execute)))))

(defun electric-help-command-loop ()
  (catch 'exit
    (if (pos-visible-in-window-p (point-max))
	(progn (message "%s" (substitute-command-keys "<<< Press Space to bury the help buffer, Press \\[electric-help-retain] to retain it >>>"))
	       (if (equal (setq unread-command-events (list (read-event)))
			  '(?\s))
		   (progn (setq unread-command-events nil)
			  (throw 'exit t)))))
    (let (up down both neither
	  (standard (and (eq (key-binding " " nil t)
			     'scroll-up)
			 (eq (key-binding "\^?" nil t)
			     'scroll-down)
			 (eq (key-binding "q" nil t)
			     'electric-help-exit)
			 (eq (key-binding "r" nil t)
			     'electric-help-retain))))
      (Electric-command-loop
        'exit
	(function (lambda ()
	  (sit-for 0) ;necessary if last command was end-of-buffer or
	              ;beginning-of-buffer - otherwise pos-visible-in-window-p
	              ;will yield a wrong result.
	  (let ((min (pos-visible-in-window-p (point-min)))
		(max (pos-visible-in-window-p (1- (point-max)))))
	    (cond (isearch-mode 'noprompt)
		  ((and min max)
		   (cond (standard "Press q to exit, r to retain ")
			 (neither)
			 (t (setq neither (substitute-command-keys "Press \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
		  (min
		   (cond (standard "Press SPC to scroll, q to exit, r to retain ")
			 (up)
			 (t (setq up (substitute-command-keys "Press \\[scroll-up] to scroll, \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
		  (max
		   (cond (standard "Press DEL to scroll back, q to exit, r to retain ")
			 (down)
			 (t (setq down (substitute-command-keys "Press \\[scroll-down] to scroll back, \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
		  (t
		   (cond (standard "Press SPC to scroll, DEL to scroll back, q to exit, r to retain ")
			 (both)
			 (t (setq both (substitute-command-keys "Press \\[scroll-up] to scroll, \\[scroll-down] to scroll back, \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))))))
		    t))))



;(defun electric-help-scroll-up (arg)
;  ">>>Doc"
;  (interactive "P")
;  (if (and (null arg) (pos-visible-in-window-p (point-max)))
;      (electric-help-exit)
;    (scroll-up arg)))

(defun electric-help-exit ()
  "Exit `with-electric-help', restoring the previous window/buffer configuration.
\(The *Help* buffer will be buried.)"
  (interactive)
  ;; Make sure that we don't throw twice, even if two events cause
  ;; calling this function:
  (if (memq 'electric-help-retain mouse-leave-buffer-hook)
      (progn
	(remove-hook 'mouse-leave-buffer-hook 'electric-help-retain)
	(throw 'exit t))))

(defun electric-help-retain ()
  "Exit `with-electric-help', retaining the current window/buffer configuration.
\(The *Help* buffer will not be selected, but \\[switch-to-buffer-other-window] RET
will select it.)"
  (interactive)
  ;; Make sure that we don't throw twice, even if two events cause
  ;; calling this function:
  (if (memq 'electric-help-retain mouse-leave-buffer-hook)
      (progn
	(remove-hook 'mouse-leave-buffer-hook 'electric-help-retain)
	(throw 'exit '(retain)))))


(defun electric-help-undefined ()
  (interactive)
  (error "%s is undefined -- Press %s to exit"
	 (mapconcat 'single-key-description (this-command-keys) " ")
	 (if (eq (key-binding "q" nil t) 'electric-help-exit)
	     "q"
	   (substitute-command-keys "\\[electric-help-exit]"))))


;>>> this needs to be hairified (recursive help, anybody?)
(defun electric-help-help ()
  (interactive)
  (if (and (eq (key-binding "q" nil t) 'electric-help-exit)
	   (eq (key-binding " " nil t) 'scroll-up)
	   (eq (key-binding "\^?" nil t) 'scroll-down)
	   (eq (key-binding "r" nil t) 'electric-help-retain))
      (message "SPC scrolls up, DEL scrolls down, q exits burying help buffer, r exits")
    (message "%s" (substitute-command-keys "\\[scroll-up] scrolls up, \\[scroll-down] scrolls down, \\[electric-help-exit] exits burying help buffer, \\[electric-help-retain] exits")))
  (sit-for 2))


;;;###autoload
(defun electric-helpify (fun &optional name)
  (let ((name (or name "*Help*")))
    (if (save-window-excursion
	  ;; kludge-o-rama
	  (let* ((p (symbol-function 'help-print-return-message))
		 (b (get-buffer name))
		 (m (buffer-modified-p b)))
	    (and b (not (get-buffer-window b))
		 (setq b nil))
	    (unwind-protect
		(progn
		  (message "%s..." (capitalize (symbol-name fun)))
		  ;; with-output-to-temp-buffer marks the buffer as unmodified.
		  ;; kludging excessively and relying on that as some sort
		  ;;  of indication leads to the following abomination...
		  ;;>> This would be doable without such icky kludges if either
		  ;;>> (a) there were a function to read the interactive
		  ;;>>     args for a command and return a list of those args.
		  ;;>>     (To which one would then just apply the command)
		  ;;>>     (The only problem with this is that interactive-p
		  ;;>>      would break, but that is such a misfeature in
		  ;;>>      any case that I don't care)
		  ;;>>     It is easy to do this for emacs-lisp functions;
		  ;;>>     the only problem is getting the interactive spec
		  ;;>>     for subrs
		  ;;>> (b) there were a function which returned a
		  ;;>>     modification-tick for a buffer.  One could tell
		  ;;>>     whether a buffer had changed by whether the
		  ;;>>     modification-tick were different.
		  ;;>>     (Presumably there would have to be a way to either
		  ;;>>      restore the tick to some previous value, or to
		  ;;>>      suspend updating of the tick in order to allow
		  ;;>>      things like momentary-string-display)
		  (and b
		       (with-current-buffer b
			 (set-buffer-modified-p t)))
		  (fset 'help-print-return-message 'ignore)
		  (call-interactively fun)
		  (and (get-buffer name)
		       (get-buffer-window (get-buffer name))
		       (or (not b)
			   (not (eq b (get-buffer name)))
			   (not (buffer-modified-p b)))))
	      (fset 'help-print-return-message p)
	      (and b (buffer-name b)
		   (with-current-buffer b
		     (set-buffer-modified-p m))))))
	(with-electric-help 'ignore name t))))



;; This is to be bound to M-x in ehelp mode. Retains ehelp buffer and then
;; continues with execute-extended-command.
(defun electric-help-execute-extended (_prefixarg)
  (interactive "p")
  (setq electric-help-form-to-execute
        (lambda () (execute-extended-command nil)))
  (electric-help-retain))

;; This is to be buond to C-x in ehelp mode. Retains ehelp buffer and then
;; continues with ctrl-x prefix.
(defun electric-help-ctrl-x-prefix (_prefixarg)
  (interactive "p")
  (setq electric-help-form-to-execute
        (lambda ()
          (message nil)
          (setq unread-command-events
                (append unread-command-events '(?\C-x)))))
  (electric-help-retain))


(defun electric-describe-key ()
  (interactive)
  (electric-helpify 'describe-key))

(defun electric-describe-mode ()
  (interactive)
  (electric-helpify 'describe-mode))

(defun electric-view-lossage ()
  (interactive)
  (electric-helpify 'view-lossage))

;(defun electric-help-for-help ()
;  "See help-for-help"
;  (interactive)
;  )

(defun electric-describe-function ()
  (interactive)
  (electric-helpify 'describe-function))

(defun electric-describe-variable ()
  (interactive)
  (electric-helpify 'describe-variable))

(defun electric-describe-bindings ()
  (interactive)
  (electric-helpify 'describe-bindings))

(defun electric-describe-syntax ()
  (interactive)
  (electric-helpify 'describe-syntax))

(defun electric-command-apropos ()
  (interactive)
  (electric-helpify 'command-apropos "*Apropos*"))

;(define-key help-map "a" 'electric-command-apropos)

(defun electric-apropos ()
  (interactive)
  (electric-helpify 'apropos))


;;;; ehelp-map

(defvar ehelp-map
  (let ((map (copy-keymap help-map)))
    (substitute-key-definition 'apropos 'electric-apropos map)
    (substitute-key-definition 'command-apropos 'electric-command-apropos map)
    (substitute-key-definition 'describe-key 'electric-describe-key map)
    (substitute-key-definition 'describe-mode 'electric-describe-mode map)
    (substitute-key-definition 'view-lossage 'electric-view-lossage map)
    (substitute-key-definition 'describe-function 'electric-describe-function map)
    (substitute-key-definition 'describe-variable 'electric-describe-variable map)
    (substitute-key-definition 'describe-bindings 'electric-describe-bindings map)
    (substitute-key-definition 'describe-syntax 'electric-describe-syntax map)
    map))

;;;###(autoload 'ehelp-command "ehelp" "Prefix command for ehelp." t 'keymap)
(defalias 'ehelp-command ehelp-map)
(put 'ehelp-command 'documentation "Prefix command for ehelp.")

(provide 'ehelp)

;;; ehelp.el ends here