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[emacs.git] / lisp / ehelp.el
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1 ;;; ehelp.el --- bindings for electric-help mode
3 ;; Copyright (C) 1986, 1995 Free Software Foundation, Inc.
5 ;; Maintainer: FSF
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)
13 ;; any later version.
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 the
22 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
23 ;; Boston, MA 02111-1307, USA.
25 ;;; Commentary:
27 ;; This package provides a pre-packaged `Electric Help Mode' for
28 ;; browsing on-line help screens. There is one entry point,
29 ;; `with-electric-help'; all you have to give it is a no-argument
30 ;; function that generates the actual text of the help into the current
31 ;; buffer.
33 ;; To make this the default, you must do
34 ;; (require 'ehelp)
35 ;; (define-key global-map "\C-h" 'ehelp-command)
36 ;; (define-key global-map [help] 'ehelp-command)
37 ;; (define-key global-map [f1] 'ehelp-command)
39 ;;; Code:
41 (require 'electric)
42 (defvar electric-help-map ()
43 "Keymap defining commands available in `electric-help-mode'.")
45 (defvar electric-help-form-to-execute nil)
47 (put 'electric-help-undefined 'suppress-keymap t)
48 (if electric-help-map
50 (let ((map (make-keymap)))
51 ;; allow all non-self-inserting keys - search, scroll, etc, but
52 ;; let M-x and C-x exit ehelp mode and retain buffer:
53 (suppress-keymap map)
54 (define-key map "\C-u" 'electric-help-undefined)
55 (define-key map [?\C-0] 'electric-help-undefined)
56 (define-key map [?\C-1] 'electric-help-undefined)
57 (define-key map [?\C-2] 'electric-help-undefined)
58 (define-key map [?\C-3] 'electric-help-undefined)
59 (define-key map [?\C-4] 'electric-help-undefined)
60 (define-key map [?\C-5] 'electric-help-undefined)
61 (define-key map [?\C-6] 'electric-help-undefined)
62 (define-key map [?\C-7] 'electric-help-undefined)
63 (define-key map [?\C-8] 'electric-help-undefined)
64 (define-key map [?\C-9] 'electric-help-undefined)
65 (define-key map (char-to-string help-char) 'electric-help-help)
66 (define-key map "?" 'electric-help-help)
67 (define-key map " " 'scroll-up)
68 (define-key map "\^?" 'scroll-down)
69 (define-key map "." 'beginning-of-buffer)
70 (define-key map "<" 'beginning-of-buffer)
71 (define-key map ">" 'end-of-buffer)
72 ;(define-key map "\C-g" 'electric-help-exit)
73 (define-key map "q" 'electric-help-exit)
74 (define-key map "Q" 'electric-help-exit)
75 ;;a better key than this?
76 (define-key map "r" 'electric-help-retain)
77 (define-key map "R" 'electric-help-retain)
78 (define-key map "\ex" 'electric-help-execute-extended)
79 (define-key map "\C-x" 'electric-help-ctrl-x-prefix)
81 (setq electric-help-map map)))
83 (defun electric-help-mode ()
84 "`with-electric-help' temporarily places its buffer in this mode.
85 \(On exit from `with-electric-help', the buffer is put in `default-major-mode'.)"
86 (setq buffer-read-only t)
87 (setq mode-name "Help")
88 (setq major-mode 'help)
89 (setq mode-line-buffer-identification '(" Help: %b"))
90 (use-local-map electric-help-map)
91 (add-hook 'mouse-leave-buffer-hook 'electric-help-retain)
92 (view-mode -1)
93 ;; this is done below in with-electric-help
94 ;(run-hooks 'electric-help-mode-hook)
97 ;;;###autoload
98 (defun with-electric-help (thunk &optional buffer noerase minheight)
99 "Pop up an \"electric\" help buffer.
100 The arguments are THUNK &optional BUFFER NOERASE MINHEIGHT.
101 THUNK is a function of no arguments which is called to initialize the
102 contents of BUFFER. BUFFER defaults to `*Help*'. BUFFER will be
103 erased before THUNK is called unless NOERASE is non-nil. THUNK will
104 be called while BUFFER is current and with `standard-output' bound to
105 the buffer specified by BUFFER.
107 If THUNK returns nil, we display BUFFER starting at the top, and
108 shrink the window to fit. If THUNK returns non-nil, we don't do those things.
110 After THUNK has been called, this function \"electrically\" pops up a window
111 in which BUFFER is displayed and allows the user to scroll through that buffer
112 in electric-help-mode. The window's height will be at least MINHEIGHT if
113 this value is non-nil.
115 If THUNK returns nil, we display BUFFER starting at the top, and
116 shrink the window to fit. If THUNK returns non-nil, we don't do those
117 things.
119 When the user exits (with `electric-help-exit', or otherwise) the help
120 buffer's window disappears (i.e., we use `save-window-excursion')
121 BUFFER is put into `default-major-mode' (or `fundamental-mode') when we exit."
122 (setq buffer (get-buffer-create (or buffer "*Help*")))
123 (let ((one (one-window-p t))
124 (config (current-window-configuration))
125 (bury nil)
126 (electric-help-form-to-execute nil))
127 (unwind-protect
128 (save-excursion
129 (if one (goto-char (window-start (selected-window))))
130 (let ((pop-up-windows t))
131 (pop-to-buffer buffer))
132 (save-excursion
133 (set-buffer buffer)
134 (if (and minheight (< (window-height) minheight))
135 (enlarge-window (- minheight (window-height))))
136 (electric-help-mode)
137 (setq buffer-read-only nil)
138 (or noerase
139 (erase-buffer)))
140 (let ((standard-output buffer))
141 (if (not (funcall thunk))
142 (progn
143 (set-buffer buffer)
144 (set-buffer-modified-p nil)
145 (goto-char (point-min))
146 (if one (shrink-window-if-larger-than-buffer (selected-window))))))
147 (set-buffer buffer)
148 (run-hooks 'electric-help-mode-hook)
149 (setq buffer-read-only t)
150 (if (eq (car-safe (electric-help-command-loop))
151 'retain)
152 (setq config (current-window-configuration))
153 (setq bury t))
154 ;; Remove the hook.
155 (if (memq 'electric-help-retain mouse-leave-buffer-hook)
156 (remove-hook 'mouse-leave-buffer-hook 'electric-help-retain)))
157 (message "")
158 (set-buffer buffer)
159 (setq buffer-read-only nil)
160 (condition-case ()
161 (funcall (or default-major-mode 'fundamental-mode))
162 (error nil))
163 (set-window-configuration config)
164 (if bury
165 (progn
166 ;;>> Perhaps this shouldn't be done.
167 ;; so that when we say "Press space to bury" we mean it
168 (replace-buffer-in-windows buffer)
169 ;; must do this outside of save-window-excursion
170 (bury-buffer buffer)))
171 (eval electric-help-form-to-execute))))
173 (defun electric-help-command-loop ()
174 (catch 'exit
175 (if (pos-visible-in-window-p (point-max))
176 (progn (message "%s" (substitute-command-keys "<<< Press Space to bury the help buffer, Press \\[electric-help-retain] to retain it >>>"))
177 (if (equal (setq unread-command-events (list (read-event)))
178 '(?\ ))
179 (progn (setq unread-command-events nil)
180 (throw 'exit t)))))
181 (let (up down both neither
182 (standard (and (eq (key-binding " ")
183 'scroll-up)
184 (eq (key-binding "\^?")
185 'scroll-down)
186 (eq (key-binding "q")
187 'electric-help-exit)
188 (eq (key-binding "r")
189 'electric-help-retain))))
190 (Electric-command-loop
191 'exit
192 (function (lambda ()
193 (sit-for 0) ;necessary if last command was end-of-buffer or
194 ;beginning-of-buffer - otherwise pos-visible-in-window-p
195 ;will yield a wrong result.
196 (let ((min (pos-visible-in-window-p (point-min)))
197 (max (pos-visible-in-window-p (point-max))))
198 (cond (isearch-mode 'noprompt)
199 ((and min max)
200 (cond (standard "Press q to exit, r to retain ")
201 (neither)
202 (t (setq neither (substitute-command-keys "Press \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
203 (min
204 (cond (standard "Press SPC to scroll, q to exit, r to retain ")
205 (up)
206 (t (setq up (substitute-command-keys "Press \\[scroll-up] to scroll, \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
207 (max
208 (cond (standard "Press DEL to scroll back, q to exit, r to retain ")
209 (down)
210 (t (setq down (substitute-command-keys "Press \\[scroll-down] to scroll back, \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
212 (cond (standard "Press SPC to scroll, DEL to scroll back, q to exit, r to retain ")
213 (both)
214 (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 ")))))))))
215 t))))
219 ;(defun electric-help-scroll-up (arg)
220 ; ">>>Doc"
221 ; (interactive "P")
222 ; (if (and (null arg) (pos-visible-in-window-p (point-max)))
223 ; (electric-help-exit)
224 ; (scroll-up arg)))
226 (defun electric-help-exit ()
227 "Exit `electric-help', restoring the previous window/buffer configuration.
228 \(The *Help* buffer will be buried.)"
229 (interactive)
230 ;; Make sure that we don't throw twice, even if two events cause
231 ;; calling this function:
232 (if (memq 'electric-help-retain mouse-leave-buffer-hook)
233 (progn
234 (remove-hook 'mouse-leave-buffer-hook 'electric-help-retain)
235 (throw 'exit t))))
237 (defun electric-help-retain ()
238 "Exit `electric-help', retaining the current window/buffer configuration.
239 \(The *Help* buffer will not be selected, but \\[switch-to-buffer-other-window] RET
240 will select it.)"
241 (interactive)
242 ;; Make sure that we don't throw twice, even if two events cause
243 ;; calling this function:
244 (if (memq 'electric-help-retain mouse-leave-buffer-hook)
245 (progn
246 (remove-hook 'mouse-leave-buffer-hook 'electric-help-retain)
247 (throw 'exit '(retain)))))
250 (defun electric-help-undefined ()
251 (interactive)
252 (error "%s is undefined -- Press %s to exit"
253 (mapconcat 'single-key-description (this-command-keys) " ")
254 (if (eq (key-binding "q") 'electric-help-exit)
256 (substitute-command-keys "\\[electric-help-exit]"))))
259 ;>>> this needs to be hairified (recursive help, anybody?)
260 (defun electric-help-help ()
261 (interactive)
262 (if (and (eq (key-binding "q") 'electric-help-exit)
263 (eq (key-binding " ") 'scroll-up)
264 (eq (key-binding "\^?") 'scroll-down)
265 (eq (key-binding "r") 'electric-help-retain))
266 (message "SPC scrolls up, DEL scrolls down, q exits burying help buffer, r exits")
267 (message "%s" (substitute-command-keys "\\[scroll-up] scrolls up, \\[scroll-down] scrolls down, \\[electric-help-exit] exits burying help buffer, \\[electric-help-retain] exits")))
268 (sit-for 2))
271 ;;;###autoload
272 (defun electric-helpify (fun &optional name)
273 (let ((name (or name "*Help*")))
274 (if (save-window-excursion
275 ;; kludge-o-rama
276 (let* ((p (symbol-function 'print-help-return-message))
277 (b (get-buffer name))
278 (m (buffer-modified-p b)))
279 (and b (not (get-buffer-window b))
280 (setq b nil))
281 (unwind-protect
282 (progn
283 (message "%s..." (capitalize (symbol-name fun)))
284 ;; with-output-to-temp-buffer marks the buffer as unmodified.
285 ;; kludging excessively and relying on that as some sort
286 ;; of indication leads to the following abomination...
287 ;;>> This would be doable without such icky kludges if either
288 ;;>> (a) there were a function to read the interactive
289 ;;>> args for a command and return a list of those args.
290 ;;>> (To which one would then just apply the command)
291 ;;>> (The only problem with this is that interactive-p
292 ;;>> would break, but that is such a misfeature in
293 ;;>> any case that I don't care)
294 ;;>> It is easy to do this for emacs-lisp functions;
295 ;;>> the only problem is getting the interactive spec
296 ;;>> for subrs
297 ;;>> (b) there were a function which returned a
298 ;;>> modification-tick for a buffer. One could tell
299 ;;>> whether a buffer had changed by whether the
300 ;;>> modification-tick were different.
301 ;;>> (Presumably there would have to be a way to either
302 ;;>> restore the tick to some previous value, or to
303 ;;>> suspend updating of the tick in order to allow
304 ;;>> things like momentary-string-display)
305 (and b
306 (save-excursion
307 (set-buffer b)
308 (set-buffer-modified-p t)))
309 (fset 'print-help-return-message 'ignore)
310 (call-interactively fun)
311 (and (get-buffer name)
312 (get-buffer-window (get-buffer name))
313 (or (not b)
314 (not (eq b (get-buffer name)))
315 (not (buffer-modified-p b)))))
316 (fset 'print-help-return-message p)
317 (and b (buffer-name b)
318 (save-excursion
319 (set-buffer b)
320 (set-buffer-modified-p m))))))
321 (with-electric-help 'ignore name t))))
325 ;; This is to be bound to M-x in ehelp mode. Retains ehelp buffer and then
326 ;; continues with execute-extended-command.
327 (defun electric-help-execute-extended (prefixarg)
328 (interactive "p")
329 (setq electric-help-form-to-execute '(execute-extended-command nil))
330 (electric-help-retain))
332 ;; This is to be buond to C-x in ehelp mode. Retains ehelp buffer and then
333 ;; continues with ctrl-x prefix.
334 (defun electric-help-ctrl-x-prefix (prefixarg)
335 (interactive "p")
336 (setq electric-help-form-to-execute '(progn (message nil) (setq unread-command-char ?\C-x)))
337 (electric-help-retain))
340 (defun electric-describe-key ()
341 (interactive)
342 (electric-helpify 'describe-key))
344 (defun electric-describe-mode ()
345 (interactive)
346 (electric-helpify 'describe-mode))
348 (defun electric-view-lossage ()
349 (interactive)
350 (electric-helpify 'view-lossage))
352 ;(defun electric-help-for-help ()
353 ; "See help-for-help"
354 ; (interactive)
357 (defun electric-describe-function ()
358 (interactive)
359 (electric-helpify 'describe-function))
361 (defun electric-describe-variable ()
362 (interactive)
363 (electric-helpify 'describe-variable))
365 (defun electric-describe-bindings ()
366 (interactive)
367 (electric-helpify 'describe-bindings))
369 (defun electric-describe-syntax ()
370 (interactive)
371 (electric-helpify 'describe-syntax))
373 (defun electric-command-apropos ()
374 (interactive)
375 (electric-helpify 'command-apropos "*Apropos*"))
377 ;(define-key help-map "a" 'electric-command-apropos)
379 (defun electric-apropos ()
380 (interactive)
381 (electric-helpify 'apropos))
384 ;;;; ehelp-map
386 (defvar ehelp-map ())
387 (if ehelp-map
389 (let ((map (copy-keymap help-map)))
390 (substitute-key-definition 'apropos 'electric-apropos map)
391 (substitute-key-definition 'command-apropos 'electric-command-apropos map)
392 (substitute-key-definition 'describe-key 'electric-describe-key map)
393 (substitute-key-definition 'describe-mode 'electric-describe-mode map)
394 (substitute-key-definition 'view-lossage 'electric-view-lossage map)
395 (substitute-key-definition 'describe-function 'electric-describe-function map)
396 (substitute-key-definition 'describe-variable 'electric-describe-variable map)
397 (substitute-key-definition 'describe-bindings 'electric-describe-bindings map)
398 (substitute-key-definition 'describe-syntax 'electric-describe-syntax map)
400 (setq ehelp-map map)
401 (fset 'ehelp-command map)))
403 (provide 'ehelp)
405 ;;; ehelp.el ends here