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, 2011  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 (defun electric-help-mode ()
  98   "`with-electric-help' temporarily places its buffer in this mode.
  99 \(On exit from `with-electric-help', the buffer is put in default `major-mode'.)"
 100   (setq buffer-read-only t)
 101   (setq mode-name "Help")
 102   (setq major-mode 'help)
 103   (setq mode-line-buffer-identification '(" Help:  %b"))
 104   (use-local-map electric-help-map)
 105   (add-hook 'mouse-leave-buffer-hook 'electric-help-retain)
 106   (view-mode -1)
 107   ;; this is done below in with-electric-help
 108   ;(run-hooks 'electric-help-mode-hook)
 109   )
 110
 111 ;;;###autoload
 112 (defun with-electric-help (thunk &optional buffer noerase minheight)
 113   "Pop up an \"electric\" help buffer.
 114 THUNK is a function of no arguments which is called to initialize the
 115 contents of BUFFER.  BUFFER defaults to `*Help*'.  BUFFER will be
 116 erased before THUNK is called unless NOERASE is non-nil.  THUNK will
 117 be called while BUFFER is current and with `standard-output' bound to
 118 the buffer specified by BUFFER.
 119
 120 If THUNK returns nil, we display BUFFER starting at the top, and shrink
 121 the window to fit.  If THUNK returns non-nil, we don't do those things.
 122
 123 After THUNK has been called, this function \"electrically\" pops up a
 124 window in which BUFFER is displayed and allows the user to scroll
 125 through that buffer in `electric-help-mode'.  The window's height will
 126 be at least MINHEIGHT if this value is non-nil.
 127
 128 If THUNK returns nil, we display BUFFER starting at the top, and
 129 shrink the window to fit if `electric-help-shrink-window' is non-nil.
 130 If THUNK returns non-nil, we don't do those things.
 131
 132 When the user exits (with `electric-help-exit', or otherwise), the help
 133 buffer's window disappears (i.e., we use `save-window-excursion'), and
 134 BUFFER is put into default `major-mode' (or `fundamental-mode')."
 135   (setq buffer (get-buffer-create (or buffer "*Help*")))
 136   (let ((one (one-window-p t))
 137         (config (current-window-configuration))
 138         (bury nil)
 139         (electric-help-form-to-execute nil))
 140     (unwind-protect
 141          (save-excursion
 142            (when one
 143              (goto-char (window-start (selected-window))))
 144            (let ((pop-up-windows t))
 145              (pop-to-buffer buffer))
 146            (with-current-buffer buffer
 147              (when (and minheight (< (window-height) minheight))
 148                (enlarge-window (- minheight (window-height))))
 149              (electric-help-mode)
 150              (setq buffer-read-only nil)
 151              (unless noerase
 152                (erase-buffer)))
 153            (let ((standard-output buffer))
 154              (unless (funcall thunk)
 155                (set-buffer buffer)
 156                (set-buffer-modified-p nil)
 157                (goto-char (point-min))
 158                (when (and one electric-help-shrink-window)
 159                  (shrink-window-if-larger-than-buffer))))
 160            (set-buffer buffer)
 161            (run-hooks 'electric-help-mode-hook)
 162            (setq buffer-read-only t)
 163            (if (eq (car-safe (electric-help-command-loop)) 'retain)
 164                (setq config (current-window-configuration))
 165              (setq bury t))
 166            ;; Remove the hook.
 167            (when (memq 'electric-help-retain mouse-leave-buffer-hook)
 168              (remove-hook 'mouse-leave-buffer-hook 'electric-help-retain)))
 169       (message "")
 170       (set-buffer buffer)
 171       (setq buffer-read-only nil)
 172
 173       ;; We should really get a usable *Help* buffer when retaining
 174       ;; the electric one with `r'.  The problem is that a simple
 175       ;; call to help-mode won't cut it; at least RET is bound wrong
 176       ;; afterwards.  It's also not clear that `help-mode' is always
 177       ;; the right thing, maybe we should add an optional parameter.
 178       (condition-case ()
 179           (funcall (or (default-value 'major-mode) 'fundamental-mode))
 180         (error nil))
 181
 182       (set-window-configuration config)
 183       (when bury
 184         ;;>> Perhaps this shouldn't be done,
 185         ;; so that when we say "Press space to bury" we mean it
 186         (replace-buffer-in-windows buffer)
 187         ;; must do this outside of save-window-excursion
 188         (bury-buffer buffer))
 189       (eval electric-help-form-to-execute))))
 190
 191 (defun electric-help-command-loop ()
 192   (catch 'exit
 193     (if (pos-visible-in-window-p (point-max))
 194         (progn (message "%s" (substitute-command-keys "<<< Press Space to bury the help buffer, Press \\[electric-help-retain] to retain it >>>"))
 195                (if (equal (setq unread-command-events (list (read-event)))
 196                           '(?\s))
 197                    (progn (setq unread-command-events nil)
 198                           (throw 'exit t)))))
 199     (let (up down both neither
 200           (standard (and (eq (key-binding " " nil t)
 201                              'scroll-up)
 202                          (eq (key-binding "\^?" nil t)
 203                              'scroll-down)
 204                          (eq (key-binding "q" nil t)
 205                              'electric-help-exit)
 206                          (eq (key-binding "r" nil t)
 207                              'electric-help-retain))))
 208       (Electric-command-loop
 209         'exit
 210         (function (lambda ()
 211           (sit-for 0) ;necessary if last command was end-of-buffer or
 212                       ;beginning-of-buffer - otherwise pos-visible-in-window-p
 213                       ;will yield a wrong result.
 214           (let ((min (pos-visible-in-window-p (point-min)))
 215                 (max (pos-visible-in-window-p (1- (point-max)))))
 216             (cond (isearch-mode 'noprompt)
 217                   ((and min max)
 218                    (cond (standard "Press q to exit, r to retain ")
 219                          (neither)
 220                          (t (setq neither (substitute-command-keys "Press \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
 221                   (min
 222                    (cond (standard "Press SPC to scroll, q to exit, r to retain ")
 223                          (up)
 224                          (t (setq up (substitute-command-keys "Press \\[scroll-up] to scroll, \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
 225                   (max
 226                    (cond (standard "Press DEL to scroll back, q to exit, r to retain ")
 227                          (down)
 228                          (t (setq down (substitute-command-keys "Press \\[scroll-down] to scroll back, \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
 229                   (t
 230                    (cond (standard "Press SPC to scroll, DEL to scroll back, q to exit, r to retain ")
 231                          (both)
 232                          (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 ")))))))))
 233                     t))))
 234
 235
 236 \f
 237 ;(defun electric-help-scroll-up (arg)
 238 ;  ">>>Doc"
 239 ;  (interactive "P")
 240 ;  (if (and (null arg) (pos-visible-in-window-p (point-max)))
 241 ;      (electric-help-exit)
 242 ;    (scroll-up arg)))
 243
 244 (defun electric-help-exit ()
 245   "Exit `with-electric-help', restoring the previous window/buffer configuration.
 246 \(The *Help* buffer will be buried.)"
 247   (interactive)
 248   ;; Make sure that we don't throw twice, even if two events cause
 249   ;; calling this function:
 250   (if (memq 'electric-help-retain mouse-leave-buffer-hook)
 251       (progn
 252         (remove-hook 'mouse-leave-buffer-hook 'electric-help-retain)
 253         (throw 'exit t))))
 254
 255 (defun electric-help-retain ()
 256   "Exit `with-electric-help', retaining the current window/buffer configuration.
 257 \(The *Help* buffer will not be selected, but \\[switch-to-buffer-other-window] RET
 258 will select it.)"
 259   (interactive)
 260   ;; Make sure that we don't throw twice, even if two events cause
 261   ;; calling this function:
 262   (if (memq 'electric-help-retain mouse-leave-buffer-hook)
 263       (progn
 264         (remove-hook 'mouse-leave-buffer-hook 'electric-help-retain)
 265         (throw 'exit '(retain)))))
 266
 267
 268 (defun electric-help-undefined ()
 269   (interactive)
 270   (error "%s is undefined -- Press %s to exit"
 271          (mapconcat 'single-key-description (this-command-keys) " ")
 272          (if (eq (key-binding "q" nil t) 'electric-help-exit)
 273              "q"
 274            (substitute-command-keys "\\[electric-help-exit]"))))
 275
 276
 277 ;>>> this needs to be hairified (recursive help, anybody?)
 278 (defun electric-help-help ()
 279   (interactive)
 280   (if (and (eq (key-binding "q" nil t) 'electric-help-exit)
 281            (eq (key-binding " " nil t) 'scroll-up)
 282            (eq (key-binding "\^?" nil t) 'scroll-down)
 283            (eq (key-binding "r" nil t) 'electric-help-retain))
 284       (message "SPC scrolls up, DEL scrolls down, q exits burying help buffer, r exits")
 285     (message "%s" (substitute-command-keys "\\[scroll-up] scrolls up, \\[scroll-down] scrolls down, \\[electric-help-exit] exits burying help buffer, \\[electric-help-retain] exits")))
 286   (sit-for 2))
 287
 288 \f
 289 ;;;###autoload
 290 (defun electric-helpify (fun &optional name)
 291   (let ((name (or name "*Help*")))
 292     (if (save-window-excursion
 293           ;; kludge-o-rama
 294           (let* ((p (symbol-function 'help-print-return-message))
 295                  (b (get-buffer name))
 296                  (m (buffer-modified-p b)))
 297             (and b (not (get-buffer-window b))
 298                  (setq b nil))
 299             (unwind-protect
 300                 (progn
 301                   (message "%s..." (capitalize (symbol-name fun)))
 302                   ;; with-output-to-temp-buffer marks the buffer as unmodified.
 303                   ;; kludging excessively and relying on that as some sort
 304                   ;;  of indication leads to the following abomination...
 305                   ;;>> This would be doable without such icky kludges if either
 306                   ;;>> (a) there were a function to read the interactive
 307                   ;;>>     args for a command and return a list of those args.
 308                   ;;>>     (To which one would then just apply the command)
 309                   ;;>>     (The only problem with this is that interactive-p
 310                   ;;>>      would break, but that is such a misfeature in
 311                   ;;>>      any case that I don't care)
 312                   ;;>>     It is easy to do this for emacs-lisp functions;
 313                   ;;>>     the only problem is getting the interactive spec
 314                   ;;>>     for subrs
 315                   ;;>> (b) there were a function which returned a
 316                   ;;>>     modification-tick for a buffer.  One could tell
 317                   ;;>>     whether a buffer had changed by whether the
 318                   ;;>>     modification-tick were different.
 319                   ;;>>     (Presumably there would have to be a way to either
 320                   ;;>>      restore the tick to some previous value, or to
 321                   ;;>>      suspend updating of the tick in order to allow
 322                   ;;>>      things like momentary-string-display)
 323                   (and b
 324                        (with-current-buffer b
 325                          (set-buffer-modified-p t)))
 326                   (fset 'help-print-return-message 'ignore)
 327                   (call-interactively fun)
 328                   (and (get-buffer name)
 329                        (get-buffer-window (get-buffer name))
 330                        (or (not b)
 331                            (not (eq b (get-buffer name)))
 332                            (not (buffer-modified-p b)))))
 333               (fset 'help-print-return-message p)
 334               (and b (buffer-name b)
 335                    (with-current-buffer b
 336                      (set-buffer-modified-p m))))))
 337         (with-electric-help 'ignore name t))))
 338
 339 \f
 340
 341 ;; This is to be bound to M-x in ehelp mode. Retains ehelp buffer and then
 342 ;; continues with execute-extended-command.
 343 (defun electric-help-execute-extended (prefixarg)
 344   (interactive "p")
 345   (setq electric-help-form-to-execute '(execute-extended-command nil))
 346   (electric-help-retain))
 347
 348 ;; This is to be buond to C-x in ehelp mode. Retains ehelp buffer and then
 349 ;; continues with ctrl-x prefix.
 350 (defun electric-help-ctrl-x-prefix (prefixarg)
 351   (interactive "p")
 352   (setq electric-help-form-to-execute '(progn (message nil) (setq unread-command-char ?\C-x)))
 353   (electric-help-retain))
 354
 355 \f
 356 (defun electric-describe-key ()
 357   (interactive)
 358   (electric-helpify 'describe-key))
 359
 360 (defun electric-describe-mode ()
 361   (interactive)
 362   (electric-helpify 'describe-mode))
 363
 364 (defun electric-view-lossage ()
 365   (interactive)
 366   (electric-helpify 'view-lossage))
 367
 368 ;(defun electric-help-for-help ()
 369 ;  "See help-for-help"
 370 ;  (interactive)
 371 ;  )
 372
 373 (defun electric-describe-function ()
 374   (interactive)
 375   (electric-helpify 'describe-function))
 376
 377 (defun electric-describe-variable ()
 378   (interactive)
 379   (electric-helpify 'describe-variable))
 380
 381 (defun electric-describe-bindings ()
 382   (interactive)
 383   (electric-helpify 'describe-bindings))
 384
 385 (defun electric-describe-syntax ()
 386   (interactive)
 387   (electric-helpify 'describe-syntax))
 388
 389 (defun electric-command-apropos ()
 390   (interactive)
 391   (electric-helpify 'command-apropos "*Apropos*"))
 392
 393 ;(define-key help-map "a" 'electric-command-apropos)
 394
 395 (defun electric-apropos ()
 396   (interactive)
 397   (electric-helpify 'apropos))
 398
 399 \f
 400 ;;;; ehelp-map
 401
 402 (defvar ehelp-map
 403   (let ((map (copy-keymap help-map)))
 404     (substitute-key-definition 'apropos 'electric-apropos map)
 405     (substitute-key-definition 'command-apropos 'electric-command-apropos map)
 406     (substitute-key-definition 'describe-key 'electric-describe-key map)
 407     (substitute-key-definition 'describe-mode 'electric-describe-mode map)
 408     (substitute-key-definition 'view-lossage 'electric-view-lossage map)
 409     (substitute-key-definition 'describe-function 'electric-describe-function map)
 410     (substitute-key-definition 'describe-variable 'electric-describe-variable map)
 411     (substitute-key-definition 'describe-bindings 'electric-describe-bindings map)
 412     (substitute-key-definition 'describe-syntax 'electric-describe-syntax map)
 413     map))
 414
 415 ;;;###(autoload 'ehelp-command "ehelp" "Prefix command for ehelp." t 'keymap)
 416 (defalias 'ehelp-command ehelp-map)
 417 (put 'ehelp-command 'documentation "Prefix command for ehelp.")
 418
 419 (provide 'ehelp)
 420
 421 ;; arch-tag: e0e3037f-42c0-433e-ba18-322c5d951f46
 422 ;;; ehelp.el ends here