lisp/ehelp.el

   1 ;;; ehelp.el --- bindings for electric-help mode
   2
   3 ;; Copyright (C) 1986, 1995, 2000, 2001, 2002, 2003, 2004, 2005, 2006,
   4 ;;   2007, 2008, 2009, 2010  Free Software Foundation, Inc.
   5
   6 ;; Author: Richard Mlynarik
   7 ;; (according to ack.texi and authors.el)
   8 ;; Maintainer: FSF
   9 ;; Keywords: help, extensions
  10
  11 ;; This file is part of GNU Emacs.
  12
  13 ;; GNU Emacs is free software: you can redistribute it and/or modify
  14 ;; it under the terms of the GNU General Public License as published by
  15 ;; the Free Software Foundation, either version 3 of the License, or
  16 ;; (at your option) any later version.
  17
  18 ;; GNU Emacs is distributed in the hope that it will be useful,
  19 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  20 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21 ;; GNU General Public License for more details.
  22
  23 ;; You should have received a copy of the GNU General Public License
  24 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  25
  26 ;;; Commentary:
  27
  28 ;; This package provides a pre-packaged `Electric Help Mode' for
  29 ;; browsing on-line help screens.  There is one entry point,
  30 ;; `with-electric-help'; all you have to give it is a no-argument
  31 ;; function that generates the actual text of the help into the current
  32 ;; buffer.
  33
  34 ;; To make this the default, you must do
  35 ;; (require 'ehelp)
  36 ;; (define-key global-map "\C-h" 'ehelp-command)
  37 ;; (define-key global-map [help] 'ehelp-command)
  38 ;; (define-key global-map [f1] 'ehelp-command)
  39
  40 ;;; Code:
  41
  42 (require 'electric)
  43
  44 (defvar electric-help-form-to-execute nil)
  45
  46 (defgroup electric-help ()
  47   "Electric help facility."
  48   :version "21.1"
  49   :group 'help)
  50
  51 (defcustom electric-help-shrink-window t
  52   "If set, adjust help window sizes to buffer sizes when displaying help."
  53   :type 'boolean
  54   :group 'electric-help)
  55
  56 (defcustom electric-help-mode-hook nil
  57   "Hook run by `with-electric-help' after initializing the buffer."
  58   :type 'hook
  59   :group 'electric-help)
  60
  61 (put 'electric-help-undefined 'suppress-keymap t)
  62
  63 (defvar electric-help-map
  64   (let ((map (make-keymap)))
  65     ;; allow all non-self-inserting keys - search, scroll, etc, but
  66     ;; let M-x and C-x exit ehelp mode and retain buffer:
  67     (suppress-keymap map)
  68     (define-key map "\C-u" 'electric-help-undefined)
  69     (define-key map [?\C-0] 'electric-help-undefined)
  70     (define-key map [?\C-1] 'electric-help-undefined)
  71     (define-key map [?\C-2] 'electric-help-undefined)
  72     (define-key map [?\C-3] 'electric-help-undefined)
  73     (define-key map [?\C-4] 'electric-help-undefined)
  74     (define-key map [?\C-5] 'electric-help-undefined)
  75     (define-key map [?\C-6] 'electric-help-undefined)
  76     (define-key map [?\C-7] 'electric-help-undefined)
  77     (define-key map [?\C-8] 'electric-help-undefined)
  78     (define-key map [?\C-9] 'electric-help-undefined)
  79     (define-key map (char-to-string help-char) 'electric-help-help)
  80     (define-key map "?" 'electric-help-help)
  81     (define-key map " " 'scroll-up)
  82     (define-key map "\^?" 'scroll-down)
  83     (define-key map "." 'beginning-of-buffer)
  84     (define-key map "<" 'beginning-of-buffer)
  85     (define-key map ">" 'end-of-buffer)
  86     ;(define-key map "\C-g" 'electric-help-exit)
  87     (define-key map "Q" 'electric-help-exit)
  88     (define-key map "q" 'electric-help-exit)
  89     ;;a better key than this?
  90     (define-key map "R" 'electric-help-retain)
  91     (define-key map "r" 'electric-help-retain)
  92     (define-key map "\ex" 'electric-help-execute-extended)
  93     (define-key map "\C-x" 'electric-help-ctrl-x-prefix)
  94     map)
  95   "Keymap defining commands available in `electric-help-mode'.")
  96
  97 (defvar electric-help-orig-major-mode nil)
  98 (make-variable-buffer-local 'electric-help-orig-major-mode)
  99
 100 (defun electric-help-mode ()
 101   "`with-electric-help' temporarily places its buffer in this mode.
 102 \(On exit from `with-electric-help', the original `major-mode' is restored.)"
 103   (setq buffer-read-only t)
 104   (setq electric-help-orig-major-mode major-mode)
 105   (setq mode-name "Help")
 106   (setq major-mode 'help)
 107   (setq mode-line-buffer-identification '(" Help:  %b"))
 108   (use-local-map electric-help-map)
 109   (add-hook 'mouse-leave-buffer-hook 'electric-help-retain)
 110   (view-mode -1)
 111   ;; this is done below in with-electric-help
 112   ;(run-hooks 'electric-help-mode-hook)
 113   )
 114
 115 ;;;###autoload
 116 (defun with-electric-help (thunk &optional buffer noerase minheight)
 117   "Pop up an \"electric\" help buffer.
 118 THUNK is a function of no arguments which is called to initialize the
 119 contents of BUFFER.  BUFFER defaults to `*Help*'.  BUFFER will be
 120 erased before THUNK is called unless NOERASE is non-nil.  THUNK will
 121 be called while BUFFER is current and with `standard-output' bound to
 122 the buffer specified by BUFFER.
 123
 124 If THUNK returns nil, we display BUFFER starting at the top, and shrink
 125 the window to fit.  If THUNK returns non-nil, we don't do those things.
 126
 127 After THUNK has been called, this function \"electrically\" pops up a
 128 window in which BUFFER is displayed and allows the user to scroll
 129 through that buffer in `electric-help-mode'.  The window's height will
 130 be at least MINHEIGHT if this value is non-nil.
 131
 132 If THUNK returns nil, we display BUFFER starting at the top, and
 133 shrink the window to fit if `electric-help-shrink-window' is non-nil.
 134 If THUNK returns non-nil, we don't do those things.
 135
 136 When the user exits (with `electric-help-exit', or otherwise), the help
 137 buffer's window disappears (i.e., we use `save-window-excursion'), and
 138 BUFFER is put back into its original major mode."
 139   (setq buffer (get-buffer-create (or buffer "*Help*")))
 140   (let ((one (one-window-p t))
 141         (config (current-window-configuration))
 142         (bury nil)
 143         (electric-help-form-to-execute nil))
 144     (unwind-protect
 145          (save-excursion
 146            (when one
 147              (goto-char (window-start (selected-window))))
 148            (let ((pop-up-windows t))
 149              (pop-to-buffer buffer))
 150            (with-current-buffer buffer
 151              (when (and minheight (< (window-height) minheight))
 152                (enlarge-window (- minheight (window-height))))
 153              (electric-help-mode)
 154              (setq buffer-read-only nil)
 155              (unless noerase
 156                (erase-buffer)))
 157            (let ((standard-output buffer))
 158              (unless (funcall thunk)
 159                (set-buffer buffer)
 160                (set-buffer-modified-p nil)
 161                (goto-char (point-min))
 162                (when (and one electric-help-shrink-window)
 163                  (shrink-window-if-larger-than-buffer))))
 164            (set-buffer buffer)
 165            (run-hooks 'electric-help-mode-hook)
 166            (setq buffer-read-only t)
 167            (if (eq (car-safe (electric-help-command-loop)) 'retain)
 168                (setq config (current-window-configuration))
 169              (setq bury t))
 170            ;; Remove the hook.
 171            (when (memq 'electric-help-retain mouse-leave-buffer-hook)
 172              (remove-hook 'mouse-leave-buffer-hook 'electric-help-retain)))
 173       (message "")
 174       (set-buffer buffer)
 175       (setq buffer-read-only nil)
 176
 177       ;; Restore the original major mode saved by `electric-help-mode'.
 178       ;; We should really get a usable *Help* buffer when retaining
 179       ;; the electric one with `r'.  The problem is that a simple
 180       ;; call to `help-mode' won't cut it; e.g. RET is bound wrong
 181       ;; afterwards (`View-scroll-line-forward' instead of `help-follow').
 182       ;; That's because Help mode should be set with `with-help-window'
 183       ;; instead of the direct call to `help-mode'. But at least
 184       ;; RET works correctly on links after using `help-mode'.
 185       ;; This is satisfactory enough.
 186       (condition-case ()
 187           (funcall (or electric-help-orig-major-mode 'fundamental-mode))
 188         (error nil))
 189
 190       (set-window-configuration config)
 191       (when bury
 192         ;;>> Perhaps this shouldn't be done,
 193         ;; so that when we say "Press space to bury" we mean it
 194         (replace-buffer-in-windows buffer)
 195         ;; must do this outside of save-window-excursion
 196         (bury-buffer buffer))
 197       (eval electric-help-form-to-execute))))
 198
 199 (defun electric-help-command-loop ()
 200   (catch 'exit
 201     (if (pos-visible-in-window-p (point-max))
 202         (progn (message "%s" (substitute-command-keys "<<< Press Space to bury the help buffer, Press \\[electric-help-retain] to retain it >>>"))
 203                (if (equal (setq unread-command-events (list (read-event)))
 204                           '(?\s))
 205                    (progn (setq unread-command-events nil)
 206                           (throw 'exit t)))))
 207     (let (up down both neither
 208           (standard (and (eq (key-binding " " nil t)
 209                              'scroll-up)
 210                          (eq (key-binding "\^?" nil t)
 211                              'scroll-down)
 212                          (eq (key-binding "q" nil t)
 213                              'electric-help-exit)
 214                          (eq (key-binding "r" nil t)
 215                              'electric-help-retain))))
 216       (Electric-command-loop
 217         'exit
 218         (function (lambda ()
 219           (sit-for 0) ;necessary if last command was end-of-buffer or
 220                       ;beginning-of-buffer - otherwise pos-visible-in-window-p
 221                       ;will yield a wrong result.
 222           (let ((min (pos-visible-in-window-p (point-min)))
 223                 (max (pos-visible-in-window-p (1- (point-max)))))
 224             (cond (isearch-mode 'noprompt)
 225                   ((and min max)
 226                    (cond (standard "Press q to exit, r to retain ")
 227                          (neither)
 228                          (t (setq neither (substitute-command-keys "Press \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
 229                   (min
 230                    (cond (standard "Press SPC to scroll, q to exit, r to retain ")
 231                          (up)
 232                          (t (setq up (substitute-command-keys "Press \\[scroll-up] to scroll, \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
 233                   (max
 234                    (cond (standard "Press DEL to scroll back, q to exit, r to retain ")
 235                          (down)
 236                          (t (setq down (substitute-command-keys "Press \\[scroll-down] to scroll back, \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
 237                   (t
 238                    (cond (standard "Press SPC to scroll, DEL to scroll back, q to exit, r to retain ")
 239                          (both)
 240                          (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 ")))))))))
 241                     t))))
 242
 243
 244 \f
 245 ;(defun electric-help-scroll-up (arg)
 246 ;  ">>>Doc"
 247 ;  (interactive "P")
 248 ;  (if (and (null arg) (pos-visible-in-window-p (point-max)))
 249 ;      (electric-help-exit)
 250 ;    (scroll-up arg)))
 251
 252 (defun electric-help-exit ()
 253   "Exit `with-electric-help', restoring the previous window/buffer configuration.
 254 \(The *Help* buffer will be buried.)"
 255   (interactive)
 256   ;; Make sure that we don't throw twice, even if two events cause
 257   ;; calling this function:
 258   (if (memq 'electric-help-retain mouse-leave-buffer-hook)
 259       (progn
 260         (remove-hook 'mouse-leave-buffer-hook 'electric-help-retain)
 261         (throw 'exit t))))
 262
 263 (defun electric-help-retain ()
 264   "Exit `with-electric-help', retaining the current window/buffer configuration.
 265 \(The *Help* buffer will not be selected, but \\[switch-to-buffer-other-window] RET
 266 will select it.)"
 267   (interactive)
 268   ;; Make sure that we don't throw twice, even if two events cause
 269   ;; calling this function:
 270   (if (memq 'electric-help-retain mouse-leave-buffer-hook)
 271       (progn
 272         (remove-hook 'mouse-leave-buffer-hook 'electric-help-retain)
 273         (throw 'exit '(retain)))))
 274
 275
 276 (defun electric-help-undefined ()
 277   (interactive)
 278   (error "%s is undefined -- Press %s to exit"
 279          (mapconcat 'single-key-description (this-command-keys) " ")
 280          (if (eq (key-binding "q" nil t) 'electric-help-exit)
 281              "q"
 282            (substitute-command-keys "\\[electric-help-exit]"))))
 283
 284
 285 ;>>> this needs to be hairified (recursive help, anybody?)
 286 (defun electric-help-help ()
 287   (interactive)
 288   (if (and (eq (key-binding "q" nil t) 'electric-help-exit)
 289            (eq (key-binding " " nil t) 'scroll-up)
 290            (eq (key-binding "\^?" nil t) 'scroll-down)
 291            (eq (key-binding "r" nil t) 'electric-help-retain))
 292       (message "SPC scrolls up, DEL scrolls down, q exits burying help buffer, r exits")
 293     (message "%s" (substitute-command-keys "\\[scroll-up] scrolls up, \\[scroll-down] scrolls down, \\[electric-help-exit] exits burying help buffer, \\[electric-help-retain] exits")))
 294   (sit-for 2))
 295
 296 \f
 297 ;;;###autoload
 298 (defun electric-helpify (fun &optional name)
 299   (let ((name (or name "*Help*")))
 300     (if (save-window-excursion
 301           ;; kludge-o-rama
 302           (let* ((p (symbol-function 'help-print-return-message))
 303                  (b (get-buffer name))
 304                  (m (buffer-modified-p b)))
 305             (and b (not (get-buffer-window b))
 306                  (setq b nil))
 307             (unwind-protect
 308                 (progn
 309                   (message "%s..." (capitalize (symbol-name fun)))
 310                   ;; with-output-to-temp-buffer marks the buffer as unmodified.
 311                   ;; kludging excessively and relying on that as some sort
 312                   ;;  of indication leads to the following abomination...
 313                   ;;>> This would be doable without such icky kludges if either
 314                   ;;>> (a) there were a function to read the interactive
 315                   ;;>>     args for a command and return a list of those args.
 316                   ;;>>     (To which one would then just apply the command)
 317                   ;;>>     (The only problem with this is that interactive-p
 318                   ;;>>      would break, but that is such a misfeature in
 319                   ;;>>      any case that I don't care)
 320                   ;;>>     It is easy to do this for emacs-lisp functions;
 321                   ;;>>     the only problem is getting the interactive spec
 322                   ;;>>     for subrs
 323                   ;;>> (b) there were a function which returned a
 324                   ;;>>     modification-tick for a buffer.  One could tell
 325                   ;;>>     whether a buffer had changed by whether the
 326                   ;;>>     modification-tick were different.
 327                   ;;>>     (Presumably there would have to be a way to either
 328                   ;;>>      restore the tick to some previous value, or to
 329                   ;;>>      suspend updating of the tick in order to allow
 330                   ;;>>      things like momentary-string-display)
 331                   (and b
 332                        (with-current-buffer b
 333                          (set-buffer-modified-p t)))
 334                   (fset 'help-print-return-message 'ignore)
 335                   (call-interactively fun)
 336                   (and (get-buffer name)
 337                        (get-buffer-window (get-buffer name))
 338                        (or (not b)
 339                            (not (eq b (get-buffer name)))
 340                            (not (buffer-modified-p b)))))
 341               (fset 'help-print-return-message p)
 342               (and b (buffer-name b)
 343                    (with-current-buffer b
 344                      (set-buffer-modified-p m))))))
 345         (with-electric-help 'ignore name t))))
 346
 347 \f
 348
 349 ;; This is to be bound to M-x in ehelp mode. Retains ehelp buffer and then
 350 ;; continues with execute-extended-command.
 351 (defun electric-help-execute-extended (prefixarg)
 352   (interactive "p")
 353   (setq electric-help-form-to-execute '(execute-extended-command nil))
 354   (electric-help-retain))
 355
 356 ;; This is to be buond to C-x in ehelp mode. Retains ehelp buffer and then
 357 ;; continues with ctrl-x prefix.
 358 (defun electric-help-ctrl-x-prefix (prefixarg)
 359   (interactive "p")
 360   (setq electric-help-form-to-execute '(progn (message nil) (setq unread-command-char ?\C-x)))
 361   (electric-help-retain))
 362
 363 \f
 364 (defun electric-describe-key ()
 365   (interactive)
 366   (electric-helpify 'describe-key))
 367
 368 (defun electric-describe-mode ()
 369   (interactive)
 370   (electric-helpify 'describe-mode))
 371
 372 (defun electric-view-lossage ()
 373   (interactive)
 374   (electric-helpify 'view-lossage))
 375
 376 ;(defun electric-help-for-help ()
 377 ;  "See help-for-help"
 378 ;  (interactive)
 379 ;  )
 380
 381 (defun electric-describe-function ()
 382   (interactive)
 383   (electric-helpify 'describe-function))
 384
 385 (defun electric-describe-variable ()
 386   (interactive)
 387   (electric-helpify 'describe-variable))
 388
 389 (defun electric-describe-bindings ()
 390   (interactive)
 391   (electric-helpify 'describe-bindings))
 392
 393 (defun electric-describe-syntax ()
 394   (interactive)
 395   (electric-helpify 'describe-syntax))
 396
 397 (defun electric-command-apropos ()
 398   (interactive)
 399   (electric-helpify 'command-apropos "*Apropos*"))
 400
 401 ;(define-key help-map "a" 'electric-command-apropos)
 402
 403 (defun electric-apropos ()
 404   (interactive)
 405   (electric-helpify 'apropos))
 406
 407 \f
 408 ;;;; ehelp-map
 409
 410 (defvar ehelp-map
 411   (let ((map (copy-keymap help-map)))
 412     (substitute-key-definition 'apropos 'electric-apropos map)
 413     (substitute-key-definition 'command-apropos 'electric-command-apropos map)
 414     (substitute-key-definition 'describe-key 'electric-describe-key map)
 415     (substitute-key-definition 'describe-mode 'electric-describe-mode map)
 416     (substitute-key-definition 'view-lossage 'electric-view-lossage map)
 417     (substitute-key-definition 'describe-function 'electric-describe-function map)
 418     (substitute-key-definition 'describe-variable 'electric-describe-variable map)
 419     (substitute-key-definition 'describe-bindings 'electric-describe-bindings map)
 420     (substitute-key-definition 'describe-syntax 'electric-describe-syntax map)
 421     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 ;; arch-tag: e0e3037f-42c0-433e-ba18-322c5d951f46
 430 ;;; ehelp.el ends here