1 ;;; ehelp.el --- bindings for electric-help mode
3 ;; Copyright (C) 1986, 1995 Free Software Foundation, Inc.
6 ;; Keywords: help, extensions
8 ;; This file is part of GNU Emacs.
10 ;; GNU Emacs is free software; you can redistribute it and/or modify
11 ;; it under the terms of the GNU General Public License as published by
12 ;; the Free Software Foundation; either version 2, or (at your option)
15 ;; GNU Emacs is distributed in the hope that it will be useful,
16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 ;; GNU General Public License for more details.
20 ;; You should have received a copy of the GNU General Public License
21 ;; along with GNU Emacs; see the file COPYING. If not, write to
22 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
26 ;; This package provides a pre-packaged `Electric Help Mode' for
27 ;; browsing on-line help screens. There is one entry point,
28 ;; `with-electric-help'; all you have to give it is a no-argument
29 ;; function that generates the actual text of the help into the current
32 ;; To make this the default, you must do
34 ;; (define-key global-map "\C-h" 'ehelp-command)
35 ;; (define-key global-map [help] 'ehelp-command)
36 ;; (define-key global-map [f1] 'ehelp-command)
41 (defvar electric-help-map
()
42 "Keymap defining commands available in `electric-help-mode'.")
44 (put 'electric-help-undefined
'suppress-keymap t
)
47 (let ((map (make-keymap)))
48 ;; allow all non-self-inserting keys - search, scroll, etc
50 (define-key map
(char-to-string help-char
) 'electric-help-help
)
51 (define-key map
"?" 'electric-help-help
)
52 (define-key map
" " 'scroll-up
)
53 (define-key map
"\^?" 'scroll-down
)
54 (define-key map
"." 'beginning-of-buffer
)
55 (define-key map
"<" 'beginning-of-buffer
)
56 (define-key map
">" 'end-of-buffer
)
57 ;(define-key map "\C-g" 'electric-help-exit)
58 (define-key map
"q" 'electric-help-exit
)
59 (define-key map
"Q" 'electric-help-exit
)
60 ;;a better key than this?
61 (define-key map
"r" 'electric-help-retain
)
62 (define-key map
"R" 'electric-help-retain
)
64 (setq electric-help-map map
)))
66 (defun electric-help-mode ()
67 "`with-electric-help' temporarily places its buffer in this mode.
68 \(On exit from `with-electric-help', the buffer is put in `default-major-mode'.)"
69 (setq buffer-read-only t
)
70 (setq mode-name
"Help")
71 (setq major-mode
'help
)
72 (setq mode-line-buffer-identification
'(" Help: %b"))
73 (use-local-map electric-help-map
)
74 ;; this is done below in with-electric-help
75 ;(run-hooks 'electric-help-mode-hook)
79 (defun with-electric-help (thunk &optional buffer noerase
)
80 "Pop up an \"electric\" help buffer.
81 Arguments are THUNK &optional BUFFER NOERASE. BUFFER defaults to `*Help*'.
82 THUNK is a function of no arguments which is called to initialize
83 the contents of BUFFER. BUFFER will be erased before THUNK is called unless
84 NOERASE is non-nil. THUNK will be called with `standard-output' bound to
85 the buffer specified by BUFFER.
87 If THUNK returns nil, we display BUFFER starting at the top, and
88 shrink the window to fit. If THUNK returns non-nil, we don't do those things.
90 After THUNK has been called, this function \"electrically\" pops up a window
91 in which BUFFER is displayed and allows the user to scroll through that buffer
92 in electric-help-mode.
93 When the user exits (with `electric-help-exit', or otherwise) the help
94 buffer's window disappears (i.e., we use `save-window-excursion')
95 BUFFER is put into `default-major-mode' (or `fundamental-mode') when we exit."
96 (setq buffer
(get-buffer-create (or buffer
"*Help*")))
97 (let ((one (one-window-p t
))
98 (config (current-window-configuration))
102 (if one
(goto-char (window-start (selected-window))))
103 (let ((pop-up-windows t
))
104 (pop-to-buffer buffer
))
108 (setq buffer-read-only nil
)
109 (or noerase
(erase-buffer)))
110 (let ((standard-output buffer
))
111 (if (not (funcall thunk
))
114 (set-buffer-modified-p nil
)
115 (goto-char (point-min))
116 (if one
(shrink-window-if-larger-than-buffer (selected-window))))))
118 (run-hooks 'electric-help-mode-hook
)
119 (if (eq (car-safe (electric-help-command-loop))
121 (setq config
(current-window-configuration))
125 (setq buffer-read-only nil
)
127 (funcall (or default-major-mode
'fundamental-mode
))
129 (set-window-configuration config
)
132 ;;>> Perhaps this shouldn't be done.
133 ;; so that when we say "Press space to bury" we mean it
134 (replace-buffer-in-windows buffer
)
135 ;; must do this outside of save-window-excursion
136 (bury-buffer buffer
))))))
138 (defun electric-help-command-loop ()
140 (if (pos-visible-in-window-p (point-max))
141 (progn (message (substitute-command-keys "<<< Press Space to bury the help buffer, Press \\[electric-help-retain] to retain it >>>"))
142 (if (equal (setq unread-command-events
(list (read-event)))
144 (progn (setq unread-command-events nil
)
146 (let (up down both neither
147 (standard (and (eq (key-binding " ")
149 (eq (key-binding "\^?")
151 (eq (key-binding "q")
153 (eq (key-binding "r")
154 'electric-help-retain
))))
155 (Electric-command-loop
158 (let ((min (pos-visible-in-window-p (point-min)))
159 (max (pos-visible-in-window-p (point-max))))
161 (cond (standard "Press q to exit, r to retain ")
163 (t (setq neither
(substitute-command-keys "Press \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
165 (cond (standard "Press SPC to scroll, q to exit, r to retain ")
167 (t (setq up
(substitute-command-keys "Press \\[scroll-up] to scroll, \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
169 (cond (standard "Press DEL to scroll back, q to exit ")
171 (t (setq down
(substitute-command-keys "Press \\[scroll-down] to scroll back, \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
173 (cond (standard "Press SPC to scroll, DEL to scroll back, q to exit ")
175 (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 ")))))))))
180 ;(defun electric-help-scroll-up (arg)
183 ; (if (and (null arg) (pos-visible-in-window-p (point-max)))
184 ; (electric-help-exit)
187 (defun electric-help-exit ()
192 (defun electric-help-retain ()
193 "Exit `electric-help', retaining the current window/buffer configuration.
194 \(The *Help* buffer will not be selected, but \\[switch-to-buffer-other-window] RET
197 (throw 'exit
'(retain)))
200 (defun electric-help-undefined ()
202 (error "%s is undefined -- Press %s to exit"
203 (mapconcat 'single-key-description
(this-command-keys) " ")
204 (if (eq (key-binding "Q") 'electric-help-exit
)
206 (substitute-command-keys "\\[electric-help-exit]"))))
209 ;>>> this needs to be hairified (recursive help, anybody?)
210 (defun electric-help-help ()
212 (if (and (eq (key-binding "q") 'electric-help-exit
)
213 (eq (key-binding " ") 'scroll-up
)
214 (eq (key-binding "\^?") 'scroll-down
)
215 (eq (key-binding "r") 'electric-help-retain
))
216 (message "SPC scrolls up, DEL scrolls down, q exits burying help buffer, r exits")
217 (message "%s" (substitute-command-keys "\\[scroll-up] scrolls up, \\[scroll-down] scrolls down, \\[electric-help-exit] exits burying help buffer, \\[electric-help-retain] exits")))
222 (defun electric-helpify (fun)
223 (let ((name "*Help*"))
224 (if (save-window-excursion
226 (let* ((p (symbol-function 'print-help-return-message
))
227 (b (get-buffer name
))
228 (m (buffer-modified-p b
)))
229 (and b
(not (get-buffer-window b
))
233 (message "%s..." (capitalize (symbol-name fun
)))
234 ;; with-output-to-temp-buffer marks the buffer as unmodified.
235 ;; kludging excessively and relying on that as some sort
236 ;; of indication leads to the following abomination...
237 ;;>> This would be doable without such icky kludges if either
238 ;;>> (a) there were a function to read the interactive
239 ;;>> args for a command and return a list of those args.
240 ;;>> (To which one would then just apply the command)
241 ;;>> (The only problem with this is that interactive-p
242 ;;>> would break, but that is such a misfeature in
243 ;;>> any case that I don't care)
244 ;;>> It is easy to do this for emacs-lisp functions;
245 ;;>> the only problem is getting the interactive spec
247 ;;>> (b) there were a function which returned a
248 ;;>> modification-tick for a buffer. One could tell
249 ;;>> whether a buffer had changed by whether the
250 ;;>> modification-tick were different.
251 ;;>> (Presumably there would have to be a way to either
252 ;;>> restore the tick to some previous value, or to
253 ;;>> suspend updating of the tick in order to allow
254 ;;>> things like momentary-string-display)
258 (set-buffer-modified-p t
)))
259 (fset 'print-help-return-message
'ignore
)
260 (call-interactively fun
)
261 (and (get-buffer name
)
262 (get-buffer-window (get-buffer name
))
264 (not (eq b
(get-buffer name
)))
265 (not (buffer-modified-p b
)))))
266 (fset 'print-help-return-message p
)
267 (and b
(buffer-name b
)
270 (set-buffer-modified-p m
))))))
271 (with-electric-help 'ignore name t
))))
274 (defun electric-describe-key ()
276 (electric-helpify 'describe-key
))
278 (defun electric-describe-mode ()
280 (electric-helpify 'describe-mode
))
282 (defun electric-view-lossage ()
284 (electric-helpify 'view-lossage
))
286 ;(defun electric-help-for-help ()
287 ; "See help-for-help"
291 (defun electric-describe-function ()
293 (electric-helpify 'describe-function
))
295 (defun electric-describe-variable ()
297 (electric-helpify 'describe-variable
))
299 (defun electric-describe-bindings ()
301 (electric-helpify 'describe-bindings
))
303 (defun electric-describe-syntax ()
305 (electric-helpify 'describe-syntax
))
307 (defun electric-command-apropos ()
309 (electric-helpify 'command-apropos
))
311 ;(define-key help-map "a" 'electric-command-apropos)
313 (defun electric-apropos ()
315 (electric-helpify 'apropos
))
320 (defvar ehelp-map
())
323 (let ((map (copy-keymap help-map
)))
324 (substitute-key-definition 'command-apropos
'electric-command-apropos map
)
325 (substitute-key-definition 'describe-key
'electric-describe-key map
)
326 (substitute-key-definition 'describe-mode
'electric-describe-mode map
)
327 (substitute-key-definition 'view-lossage
'electric-view-lossage map
)
328 (substitute-key-definition 'describe-function
'electric-describe-function map
)
329 (substitute-key-definition 'describe-variable
'electric-describe-variable map
)
330 (substitute-key-definition 'describe-bindings
'electric-describe-bindings map
)
331 (substitute-key-definition 'describe-syntax
'electric-describe-syntax map
)
334 (fset 'ehelp-command map
)))
338 ;;; ehelp.el ends here