lisp/ehelp.el

   1 ;;; ehelp.el --- bindings for electric-help mode
   2
   3 ;; Copyright (C) 1986, 1995 Free Software Foundation, Inc.
   4
   5 ;; Maintainer: FSF
   6 ;; Keywords: help, extensions
   7
   8 ;; This file is part of GNU Emacs.
   9
  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.
  14
  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.
  19
  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.
  24
  25 ;;; Commentary:
  26
  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.
  32
  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)
  38
  39 ;;; Code:
  40
  41 (require 'electric)
  42 (defvar electric-help-map ()
  43   "Keymap defining commands available in `electric-help-mode'.")
  44
  45 (defvar electric-help-form-to-execute nil)
  46
  47 (put 'electric-help-undefined 'suppress-keymap t)
  48 (if electric-help-map
  49     ()
  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)
  80
  81     (setq electric-help-map map)))
  82
  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)
  95   )
  96
  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.
 106
 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.
 109
 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.
 114
 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.
 118
 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))))
 172
 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 ")))))
 211                   (t
 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))))
 216
 217
 218 \f
 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)))
 225
 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))))
 236
 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)))))
 248
 249
 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)
 255              "q"
 256            (substitute-command-keys "\\[electric-help-exit]"))))
 257
 258
 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))
 269
 270 \f
 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))))
 322
 323 \f
 324
 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))
 331
 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))
 338
 339 \f
 340 (defun electric-describe-key ()
 341   (interactive)
 342   (electric-helpify 'describe-key))
 343
 344 (defun electric-describe-mode ()
 345   (interactive)
 346   (electric-helpify 'describe-mode))
 347
 348 (defun electric-view-lossage ()
 349   (interactive)
 350   (electric-helpify 'view-lossage))
 351
 352 ;(defun electric-help-for-help ()
 353 ;  "See help-for-help"
 354 ;  (interactive)
 355 ;  )
 356
 357 (defun electric-describe-function ()
 358   (interactive)
 359   (electric-helpify 'describe-function))
 360
 361 (defun electric-describe-variable ()
 362   (interactive)
 363   (electric-helpify 'describe-variable))
 364
 365 (defun electric-describe-bindings ()
 366   (interactive)
 367   (electric-helpify 'describe-bindings))
 368
 369 (defun electric-describe-syntax ()
 370   (interactive)
 371   (electric-helpify 'describe-syntax))
 372
 373 (defun electric-command-apropos ()
 374   (interactive)
 375   (electric-helpify 'command-apropos "*Apropos*"))
 376
 377 ;(define-key help-map "a" 'electric-command-apropos)
 378
 379 (defun electric-apropos ()
 380   (interactive)
 381   (electric-helpify 'apropos))
 382
 383 \f
 384 ;;;; ehelp-map
 385
 386 (defvar ehelp-map ())
 387 (if ehelp-map
 388     nil
 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)
 399
 400     (setq ehelp-map map)
 401     (fset 'ehelp-command map)))
 402
 403 (provide 'ehelp)
 404
 405 ;;; ehelp.el ends here