lisp/ehelp.el

   1 ;;; ehelp.el --- bindings for electric-help mode
   2
   3 ;; Copyright (C) 1986, 1995, 2000, 2001 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 (defgroup electric-help ()
  48   "Electric help facility."
  49   :version "21.1"
  50   :group 'help)
  51
  52 (defcustom electric-help-shrink-window t
  53   "If set, adjust help window sizes to buffer sizes when displaying help."
  54   :type 'boolean
  55   :group 'electric-help)
  56
  57 (defcustom electric-help-mode-hook nil
  58   "Hook run by `with-electric-help' after initializing the buffer."
  59   :type 'hook
  60   :group 'electric-help)
  61
  62 (put 'electric-help-undefined 'suppress-keymap t)
  63 (if electric-help-map
  64     ()
  65   (let ((map (make-keymap)))
  66     ;; allow all non-self-inserting keys - search, scroll, etc, but
  67     ;; let M-x and C-x exit ehelp mode and retain buffer:
  68     (suppress-keymap map)
  69     (define-key map "\C-u" 'electric-help-undefined)
  70     (define-key map [?\C-0] 'electric-help-undefined)
  71     (define-key map [?\C-1] 'electric-help-undefined)
  72     (define-key map [?\C-2] 'electric-help-undefined)
  73     (define-key map [?\C-3] 'electric-help-undefined)
  74     (define-key map [?\C-4] 'electric-help-undefined)
  75     (define-key map [?\C-5] 'electric-help-undefined)
  76     (define-key map [?\C-6] 'electric-help-undefined)
  77     (define-key map [?\C-7] 'electric-help-undefined)
  78     (define-key map [?\C-8] 'electric-help-undefined)
  79     (define-key map [?\C-9] 'electric-help-undefined)
  80     (define-key map (char-to-string help-char) 'electric-help-help)
  81     (define-key map "?" 'electric-help-help)
  82     (define-key map " " 'scroll-up)
  83     (define-key map "\^?" 'scroll-down)
  84     (define-key map "." 'beginning-of-buffer)
  85     (define-key map "<" 'beginning-of-buffer)
  86     (define-key map ">" 'end-of-buffer)
  87     ;(define-key map "\C-g" 'electric-help-exit)
  88     (define-key map "q" 'electric-help-exit)
  89     (define-key map "Q" 'electric-help-exit)
  90     ;;a better key than this?
  91     (define-key map "r" 'electric-help-retain)
  92     (define-key map "R" 'electric-help-retain)
  93     (define-key map "\ex" 'electric-help-execute-extended)
  94     (define-key map "\C-x" 'electric-help-ctrl-x-prefix)
  95
  96     (setq electric-help-map map)))
  97
  98 (defun electric-help-mode ()
  99   "`with-electric-help' temporarily places its buffer in this mode.
 100 \(On exit from `with-electric-help', the buffer is put in `default-major-mode'.)"
 101   (setq buffer-read-only t)
 102   (setq mode-name "Help")
 103   (setq major-mode 'help)
 104   (setq mode-line-buffer-identification '(" Help:  %b"))
 105   (use-local-map electric-help-map)
 106   (add-hook 'mouse-leave-buffer-hook 'electric-help-retain)
 107   (view-mode -1)
 108   ;; this is done below in with-electric-help
 109   ;(run-hooks 'electric-help-mode-hook)
 110   )
 111
 112 ;;;###autoload
 113 (defun with-electric-help (thunk &optional buffer noerase minheight)
 114   "Pop up an \"electric\" help buffer.
 115 The arguments are THUNK &optional BUFFER NOERASE MINHEIGHT.
 116 THUNK is a function of no arguments which is called to initialize the
 117 contents of BUFFER.  BUFFER defaults to `*Help*'.  BUFFER will be
 118 erased before THUNK is called unless NOERASE is non-nil.  THUNK will
 119 be called while BUFFER is current and with `standard-output' bound to
 120 the buffer specified by BUFFER.
 121
 122 If THUNK returns nil, we display BUFFER starting at the top, and
 123 shrink the window to fit.  If THUNK returns non-nil, we don't do those things.
 124
 125 After THUNK has been called, this function \"electrically\" pops up a window
 126 in which BUFFER is displayed and allows the user to scroll through that buffer
 127 in electric-help-mode. The window's height will be at least MINHEIGHT if
 128 this value is non-nil.
 129
 130 If THUNK returns nil, we display BUFFER starting at the top, and
 131 shrink the window to fit if `electric-help-shrink-window' is non-nil.
 132 If THUNK returns non-nil, we don't do those things.
 133
 134 When the user exits (with `electric-help-exit', or otherwise), the help
 135 buffer's window disappears (i.e., we use `save-window-excursion'), and
 136 BUFFER is put into `default-major-mode' (or `fundamental-mode') when we exit."
 137   (setq buffer (get-buffer-create (or buffer "*Help*")))
 138   (let ((one (one-window-p t))
 139         (config (current-window-configuration))
 140         (bury nil)
 141         (electric-help-form-to-execute nil))
 142     (unwind-protect
 143          (save-excursion
 144            (when one
 145              (goto-char (window-start (selected-window))))
 146            (let ((pop-up-windows t))
 147              (pop-to-buffer buffer))
 148            (save-excursion
 149              (set-buffer buffer)
 150              (when (and minheight (< (window-height) minheight))
 151                (enlarge-window (- minheight (window-height))))
 152              (electric-help-mode)
 153              (setq buffer-read-only nil)
 154              (unless noerase
 155                (erase-buffer)))
 156            (let ((standard-output buffer))
 157              (unless (funcall thunk)
 158                (set-buffer buffer)
 159                (set-buffer-modified-p nil)
 160                (goto-char (point-min))
 161                (when (and one electric-help-shrink-window)
 162                  (shrink-window-if-larger-than-buffer))))
 163            (set-buffer buffer)
 164            (run-hooks 'electric-help-mode-hook)
 165            (setq buffer-read-only t)
 166            (if (eq (car-safe (electric-help-command-loop)) 'retain)
 167                (setq config (current-window-configuration))
 168              (setq bury t))
 169            ;; Remove the hook.
 170            (when (memq 'electric-help-retain mouse-leave-buffer-hook)
 171              (remove-hook 'mouse-leave-buffer-hook 'electric-help-retain)))
 172       (message "")
 173       (set-buffer buffer)
 174       (setq buffer-read-only nil)
 175
 176       ;; We should really get a usable *Help* buffer when retaining
 177       ;; the electric one with `r'.  The problem is that a simple
 178       ;; call to help-mode won't cut it; at least RET is bound wrong
 179       ;; afterwards.  It's also not clear that `help-mode' is always
 180       ;; the right thing, maybe we should add an optional parameter.
 181       (condition-case ()
 182           (funcall (or default-major-mode 'fundamental-mode))
 183         (error nil))
 184
 185       (set-window-configuration config)
 186       (when bury
 187         ;;>> Perhaps this shouldn't be done,
 188         ;; so that when we say "Press space to bury" we mean it
 189         (replace-buffer-in-windows buffer)
 190         ;; must do this outside of save-window-excursion
 191         (bury-buffer buffer))
 192       (eval electric-help-form-to-execute))))
 193
 194 (defun electric-help-command-loop ()
 195   (catch 'exit
 196     (if (pos-visible-in-window-p (point-max))
 197         (progn (message "%s" (substitute-command-keys "<<< Press Space to bury the help buffer, Press \\[electric-help-retain] to retain it >>>"))
 198                (if (equal (setq unread-command-events (list (read-event)))
 199                           '(?\ ))
 200                    (progn (setq unread-command-events nil)
 201                           (throw 'exit t)))))
 202     (let (up down both neither
 203           (standard (and (eq (key-binding " ")
 204                              'scroll-up)
 205                          (eq (key-binding "\^?")
 206                              'scroll-down)
 207                          (eq (key-binding "q")
 208                              'electric-help-exit)
 209                          (eq (key-binding "r")
 210                              'electric-help-retain))))
 211       (Electric-command-loop
 212         'exit
 213         (function (lambda ()
 214           (sit-for 0) ;necessary if last command was end-of-buffer or
 215                       ;beginning-of-buffer - otherwise pos-visible-in-window-p
 216                       ;will yield a wrong result.
 217           (let ((min (pos-visible-in-window-p (point-min)))
 218                 (max (pos-visible-in-window-p (point-max))))
 219             (cond (isearch-mode 'noprompt)
 220                   ((and min max)
 221                    (cond (standard "Press q to exit, r to retain ")
 222                          (neither)
 223                          (t (setq neither (substitute-command-keys "Press \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
 224                   (min
 225                    (cond (standard "Press SPC to scroll, q to exit, r to retain ")
 226                          (up)
 227                          (t (setq up (substitute-command-keys "Press \\[scroll-up] to scroll, \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
 228                   (max
 229                    (cond (standard "Press DEL to scroll back, q to exit, r to retain ")
 230                          (down)
 231                          (t (setq down (substitute-command-keys "Press \\[scroll-down] to scroll back, \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
 232                   (t
 233                    (cond (standard "Press SPC to scroll, DEL to scroll back, q to exit, r to retain ")
 234                          (both)
 235                          (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 ")))))))))
 236                     t))))
 237
 238
 239 \f
 240 ;(defun electric-help-scroll-up (arg)
 241 ;  ">>>Doc"
 242 ;  (interactive "P")
 243 ;  (if (and (null arg) (pos-visible-in-window-p (point-max)))
 244 ;      (electric-help-exit)
 245 ;    (scroll-up arg)))
 246
 247 (defun electric-help-exit ()
 248   "Exit `electric-help', restoring the previous window/buffer configuration.
 249 \(The *Help* buffer will be buried.)"
 250   (interactive)
 251   ;; Make sure that we don't throw twice, even if two events cause
 252   ;; calling this function:
 253   (if (memq 'electric-help-retain mouse-leave-buffer-hook)
 254       (progn
 255         (remove-hook 'mouse-leave-buffer-hook 'electric-help-retain)
 256         (throw 'exit t))))
 257
 258 (defun electric-help-retain ()
 259   "Exit `electric-help', retaining the current window/buffer configuration.
 260 \(The *Help* buffer will not be selected, but \\[switch-to-buffer-other-window] RET
 261 will select it.)"
 262   (interactive)
 263   ;; Make sure that we don't throw twice, even if two events cause
 264   ;; calling this function:
 265   (if (memq 'electric-help-retain mouse-leave-buffer-hook)
 266       (progn
 267         (remove-hook 'mouse-leave-buffer-hook 'electric-help-retain)
 268         (throw 'exit '(retain)))))
 269
 270
 271 (defun electric-help-undefined ()
 272   (interactive)
 273   (error "%s is undefined -- Press %s to exit"
 274          (mapconcat 'single-key-description (this-command-keys) " ")
 275          (if (eq (key-binding "q") 'electric-help-exit)
 276              "q"
 277            (substitute-command-keys "\\[electric-help-exit]"))))
 278
 279
 280 ;>>> this needs to be hairified (recursive help, anybody?)
 281 (defun electric-help-help ()
 282   (interactive)
 283   (if (and (eq (key-binding "q") 'electric-help-exit)
 284            (eq (key-binding " ") 'scroll-up)
 285            (eq (key-binding "\^?") 'scroll-down)
 286            (eq (key-binding "r") 'electric-help-retain))
 287       (message "SPC scrolls up, DEL scrolls down, q exits burying help buffer, r exits")
 288     (message "%s" (substitute-command-keys "\\[scroll-up] scrolls up, \\[scroll-down] scrolls down, \\[electric-help-exit] exits burying help buffer, \\[electric-help-retain] exits")))
 289   (sit-for 2))
 290
 291 \f
 292 ;;;###autoload
 293 (defun electric-helpify (fun &optional name)
 294   (let ((name (or name "*Help*")))
 295     (if (save-window-excursion
 296           ;; kludge-o-rama
 297           (let* ((p (symbol-function 'print-help-return-message))
 298                  (b (get-buffer name))
 299                  (m (buffer-modified-p b)))
 300             (and b (not (get-buffer-window b))
 301                  (setq b nil))
 302             (unwind-protect
 303                 (progn
 304                   (message "%s..." (capitalize (symbol-name fun)))
 305                   ;; with-output-to-temp-buffer marks the buffer as unmodified.
 306                   ;; kludging excessively and relying on that as some sort
 307                   ;;  of indication leads to the following abomination...
 308                   ;;>> This would be doable without such icky kludges if either
 309                   ;;>> (a) there were a function to read the interactive
 310                   ;;>>     args for a command and return a list of those args.
 311                   ;;>>     (To which one would then just apply the command)
 312                   ;;>>     (The only problem with this is that interactive-p
 313                   ;;>>      would break, but that is such a misfeature in
 314                   ;;>>      any case that I don't care)
 315                   ;;>>     It is easy to do this for emacs-lisp functions;
 316                   ;;>>     the only problem is getting the interactive spec
 317                   ;;>>     for subrs
 318                   ;;>> (b) there were a function which returned a
 319                   ;;>>     modification-tick for a buffer.  One could tell
 320                   ;;>>     whether a buffer had changed by whether the
 321                   ;;>>     modification-tick were different.
 322                   ;;>>     (Presumably there would have to be a way to either
 323                   ;;>>      restore the tick to some previous value, or to
 324                   ;;>>      suspend updating of the tick in order to allow
 325                   ;;>>      things like momentary-string-display)
 326                   (and b
 327                        (save-excursion
 328                          (set-buffer b)
 329                          (set-buffer-modified-p t)))
 330                   (fset 'print-help-return-message 'ignore)
 331                   (call-interactively fun)
 332                   (and (get-buffer name)
 333                        (get-buffer-window (get-buffer name))
 334                        (or (not b)
 335                            (not (eq b (get-buffer name)))
 336                            (not (buffer-modified-p b)))))
 337               (fset 'print-help-return-message p)
 338               (and b (buffer-name b)
 339                    (save-excursion
 340                      (set-buffer b)
 341                      (set-buffer-modified-p m))))))
 342         (with-electric-help 'ignore name t))))
 343
 344 \f
 345
 346 ;; This is to be bound to M-x in ehelp mode. Retains ehelp buffer and then
 347 ;; continues with execute-extended-command.
 348 (defun electric-help-execute-extended (prefixarg)
 349   (interactive "p")
 350   (setq electric-help-form-to-execute '(execute-extended-command nil))
 351   (electric-help-retain))
 352
 353 ;; This is to be buond to C-x in ehelp mode. Retains ehelp buffer and then
 354 ;; continues with ctrl-x prefix.
 355 (defun electric-help-ctrl-x-prefix (prefixarg)
 356   (interactive "p")
 357   (setq electric-help-form-to-execute '(progn (message nil) (setq unread-command-char ?\C-x)))
 358   (electric-help-retain))
 359
 360 \f
 361 (defun electric-describe-key ()
 362   (interactive)
 363   (electric-helpify 'describe-key))
 364
 365 (defun electric-describe-mode ()
 366   (interactive)
 367   (electric-helpify 'describe-mode))
 368
 369 (defun electric-view-lossage ()
 370   (interactive)
 371   (electric-helpify 'view-lossage))
 372
 373 ;(defun electric-help-for-help ()
 374 ;  "See help-for-help"
 375 ;  (interactive)
 376 ;  )
 377
 378 (defun electric-describe-function ()
 379   (interactive)
 380   (electric-helpify 'describe-function))
 381
 382 (defun electric-describe-variable ()
 383   (interactive)
 384   (electric-helpify 'describe-variable))
 385
 386 (defun electric-describe-bindings ()
 387   (interactive)
 388   (electric-helpify 'describe-bindings))
 389
 390 (defun electric-describe-syntax ()
 391   (interactive)
 392   (electric-helpify 'describe-syntax))
 393
 394 (defun electric-command-apropos ()
 395   (interactive)
 396   (electric-helpify 'command-apropos "*Apropos*"))
 397
 398 ;(define-key help-map "a" 'electric-command-apropos)
 399
 400 (defun electric-apropos ()
 401   (interactive)
 402   (electric-helpify 'apropos))
 403
 404 \f
 405 ;;;; ehelp-map
 406
 407 (defvar ehelp-map ())
 408 (if ehelp-map
 409     nil
 410   (let ((map (copy-keymap help-map)))
 411     (substitute-key-definition 'apropos 'electric-apropos map)
 412     (substitute-key-definition 'command-apropos 'electric-command-apropos map)
 413     (substitute-key-definition 'describe-key 'electric-describe-key map)
 414     (substitute-key-definition 'describe-mode 'electric-describe-mode map)
 415     (substitute-key-definition 'view-lossage 'electric-view-lossage map)
 416     (substitute-key-definition 'describe-function 'electric-describe-function map)
 417     (substitute-key-definition 'describe-variable 'electric-describe-variable map)
 418     (substitute-key-definition 'describe-bindings 'electric-describe-bindings map)
 419     (substitute-key-definition 'describe-syntax 'electric-describe-syntax map)
 420
 421     (setq ehelp-map map)))
 422
 423 ;;;###(autoload 'ehelp-command "ehelp" "Prefix command for ehelp." t 'keymap)
 424 (defalias 'ehelp-command ehelp-map)
 425 (put 'ehelp-command 'documentation "Prefix command for ehelp.")
 426
 427 (provide 'ehelp)
 428
 429 ;;; ehelp.el ends here