help.el 25.4 KB
Newer Older
Eric S. Raymond's avatar
Eric S. Raymond committed
1 2
;;; help.el --- help commands for Emacs

Karl Heuer's avatar
Karl Heuer committed
3
;; Copyright (C) 1985, 1986, 1993, 1994 Free Software Foundation, Inc.
Eric S. Raymond's avatar
Eric S. Raymond committed
4

Eric S. Raymond's avatar
Eric S. Raymond committed
5
;; Maintainer: FSF
Eric S. Raymond's avatar
Eric S. Raymond committed
6
;; Keywords: help, internal
Eric S. Raymond's avatar
Eric S. Raymond committed
7

Richard M. Stallman's avatar
Richard M. Stallman committed
8 9 10 11
;; This file is part of GNU Emacs.

;; GNU Emacs is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
Eric S. Raymond's avatar
Eric S. Raymond committed
12
;; the Free Software Foundation; either version 2, or (at your option)
Richard M. Stallman's avatar
Richard M. Stallman committed
13 14 15 16 17 18 19 20
;; any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
Erik Naggum's avatar
Erik Naggum committed
21 22 23
;; along with GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.
Richard M. Stallman's avatar
Richard M. Stallman committed
24

25 26
;;; Commentary:

27
;; This code implements GNU Emacs' on-line help system, the one invoked by
28 29
;;`M-x help-for-help'.

Eric S. Raymond's avatar
Eric S. Raymond committed
30 31
;;; Code:

32 33
;; Get the macro make-help-screen when this is compiled,
;; or run interpreted, but not when the compiled code is loaded.
34
(eval-when-compile (require 'help-macro))
35

Richard M. Stallman's avatar
Richard M. Stallman committed
36 37 38
(defvar help-map (make-sparse-keymap)
  "Keymap for characters following the Help key.")

Karl Heuer's avatar
Karl Heuer committed
39 40 41
(defvar help-mode-map (make-sparse-keymap)
  "Keymap for help mode.")

Eric S. Raymond's avatar
Eric S. Raymond committed
42
(define-key global-map (char-to-string help-char) 'help-command)
43 44
(define-key global-map [help] 'help-command)
(define-key global-map [f1] 'help-command)
Richard M. Stallman's avatar
Richard M. Stallman committed
45 46
(fset 'help-command help-map)

Eric S. Raymond's avatar
Eric S. Raymond committed
47
(define-key help-map (char-to-string help-char) 'help-for-help)
48 49
(define-key help-map [help] 'help-for-help)
(define-key help-map [f1] 'help-for-help)
Richard M. Stallman's avatar
Richard M. Stallman committed
50 51 52 53 54
(define-key help-map "?" 'help-for-help)

(define-key help-map "\C-c" 'describe-copying)
(define-key help-map "\C-d" 'describe-distribution)
(define-key help-map "\C-w" 'describe-no-warranty)
55
(define-key help-map "\C-p" 'describe-project)
56
(define-key help-map "a" 'apropos-command)
Richard M. Stallman's avatar
Richard M. Stallman committed
57 58 59 60 61 62 63 64 65

(define-key help-map "b" 'describe-bindings)

(define-key help-map "c" 'describe-key-briefly)
(define-key help-map "k" 'describe-key)

(define-key help-map "d" 'describe-function)
(define-key help-map "f" 'describe-function)

66 67
(define-key help-map "F" 'view-emacs-FAQ)

Richard M. Stallman's avatar
Richard M. Stallman committed
68
(define-key help-map "i" 'info)
Jim Blandy's avatar
Jim Blandy committed
69 70
(define-key help-map "\C-f" 'Info-goto-emacs-command-node)
(define-key help-map "\C-k" 'Info-goto-emacs-key-command-node)
71
(define-key help-map "\C-i" 'info-lookup-symbol)
Richard M. Stallman's avatar
Richard M. Stallman committed
72 73 74 75 76 77 78 79

(define-key help-map "l" 'view-lossage)

(define-key help-map "m" 'describe-mode)

(define-key help-map "\C-n" 'view-emacs-news)
(define-key help-map "n" 'view-emacs-news)

80
(define-key help-map "p" 'finder-by-keyword)
81 82
(autoload 'finder-by-keyword "finder"
  "Find packages matching a given keyword." t)
83

Richard M. Stallman's avatar
Richard M. Stallman committed
84 85 86 87 88 89 90 91
(define-key help-map "s" 'describe-syntax)

(define-key help-map "t" 'help-with-tutorial)

(define-key help-map "w" 'where-is)

(define-key help-map "v" 'describe-variable)

Richard M. Stallman's avatar
Richard M. Stallman committed
92 93
(define-key help-map "q" 'help-quit)

Simon Marshall's avatar
Simon Marshall committed
94
(defvar help-font-lock-keywords
95 96 97 98 99 100
  (eval-when-compile
    (let ((name-char "[-+a-zA-Z0-9_*]") (sym-char "[-+a-zA-Z0-9_:*]"))
      (list
       ;;
       ;; The symbol itself.
       (list (concat "\\`\\(" name-char "+\\)\\(\\(:\\)\\|\\('\\)\\)")
101 102
	     '(1 (if (match-beginning 3)
		     font-lock-function-name-face
103
		   font-lock-variable-name-face)))
104 105 106 107 108 109 110
       ;;
       ;; Words inside `' which tend to be symbol names.
       (list (concat "`\\(" sym-char sym-char "+\\)'")
	     1 'font-lock-reference-face t)
       ;;
       ;; CLisp `:' keywords as references.
       (list (concat "\\<:" sym-char "+\\>") 0 'font-lock-reference-face t))))
Simon Marshall's avatar
Simon Marshall committed
111 112
  "Default expressions to highlight in Help mode.")

Karl Heuer's avatar
Karl Heuer committed
113 114 115 116 117 118 119 120 121 122
(defun help-mode ()
  "Major mode for viewing help text.
Entry to this mode runs the normal hook `help-mode-hook'.
Commands:
\\{help-mode-map}"
  (interactive)
  (kill-all-local-variables)
  (use-local-map help-mode-map)
  (setq mode-name "Help")
  (setq major-mode 'help-mode)
Simon Marshall's avatar
Simon Marshall committed
123
  (make-local-variable 'font-lock-defaults)
124
  (setq font-lock-defaults '(help-font-lock-keywords))
125
  (view-mode)
126 127
  (make-local-variable 'view-no-disable-on-exit)
  (setq view-no-disable-on-exit t)
Karl Heuer's avatar
Karl Heuer committed
128 129
  (run-hooks 'help-mode-hook))

Richard M. Stallman's avatar
Richard M. Stallman committed
130 131 132 133
(defun help-quit ()
  (interactive)
  nil)

134 135
(defun help-with-tutorial (&optional arg)
  "Select the Emacs learn-by-doing tutorial.
136 137 138 139
If there is a tutorial version written in the language
of the selected anguage envgironment, that version is used.
If there's no tutorial in that language, `TUTORIAL' is selected.
With arg, you are asked to select which language."
140
  (interactive "P")
141 142 143 144
  (let (lang filename file)
    (if arg
	(or (setq lang (read-language-name 'tutorial "Language: "))
	    (error "No tutorial file of the specified language"))
145
      (setq lang current-language-environment))
146 147 148
    (setq filename (or (get-language-info lang 'tutorial)
		       "TUTORIAL"))
    (setq file (expand-file-name (concat "~/" filename)))
Richard M. Stallman's avatar
Richard M. Stallman committed
149 150 151 152 153 154
    (delete-other-windows)
    (if (get-file-buffer file)
	(switch-to-buffer (get-file-buffer file))
      (switch-to-buffer (create-file-buffer file))
      (setq buffer-file-name file)
      (setq default-directory (expand-file-name "~/"))
Jim Blandy's avatar
Jim Blandy committed
155
      (setq buffer-auto-save-file-name nil)
156
      (insert-file-contents (expand-file-name filename data-directory))
Richard M. Stallman's avatar
Richard M. Stallman committed
157 158 159 160
      (goto-char (point-min))
      (search-forward "\n<<")
      (beginning-of-line)
      (delete-region (point) (progn (end-of-line) (point)))
161
      (let ((n (- (window-height (selected-window))
Richard M. Stallman's avatar
Richard M. Stallman committed
162
		  (count-lines (point-min) (point))
163
		  6)))
164
	(if (< n 12)
165 166 167 168 169 170
	    (newline n)
	  ;; Some people get confused by the large gap.
	  (newline (/ n 2))
	  (insert "[Middle of page left blank for didactic purposes.  "
		  "Text continues below]")
	  (newline (- n (/ n 2)))))
Richard M. Stallman's avatar
Richard M. Stallman committed
171 172 173
      (goto-char (point-min))
      (set-buffer-modified-p nil))))

174 175 176 177
(defun describe-key-briefly (key &optional insert)
  "Print the name of the function KEY invokes.  KEY is a string.
If INSERT (the prefix arg) is non-nil, insert the message in the buffer."
  (interactive "kDescribe key briefly: \nP")
178 179 180 181 182 183 184
  ;; If this key seq ends with a down event, discard the
  ;; following click or drag event.  Otherwise that would
  ;; erase the message.
  (let ((type (aref key (1- (length key)))))
    (if (listp type) (setq type (car type)))
    (and (symbolp type)
	 (memq 'down (event-modifiers type))
185
	 (read-event)))
186 187
  (save-excursion
    (let ((modifiers (event-modifiers (aref key 0)))
188
	  (standard-output (if insert (current-buffer) t))
189 190 191 192 193 194 195 196 197 198 199 200 201
	  window position)
      ;; For a mouse button event, go to the button it applies to
      ;; to get the right key bindings.  And go to the right place
      ;; in case the keymap depends on where you clicked.
      (if (or (memq 'click modifiers) (memq 'down modifiers)
	      (memq 'drag modifiers))
	  (setq window (posn-window (event-start (aref key 0)))
		position (posn-point (event-start (aref key 0)))))
      (if (windowp window)
	  (progn
	    (set-buffer (window-buffer window))
	    (goto-char position)))
      ;; Ok, now look up the key and name the command.
202 203
      (let ((defn (key-binding key))
	    (key-desc (key-description key)))
204
	(if (or (null defn) (integerp defn))
205 206 207 208 209 210 211 212
	    (princ (format "%s is undefined" key-desc))
	  (princ (format (if insert
			     "%s (%s)"
			   (if (windowp window)
			       "%s at that spot runs the command %s"
			     "%s runs the command %s"))
			 key-desc
			 (if (symbolp defn) defn (prin1-to-string defn)))))))))
Richard M. Stallman's avatar
Richard M. Stallman committed
213 214 215 216 217 218

(defun print-help-return-message (&optional function)
  "Display or return message saying how to restore windows after help command.
Computes a message and applies the optional argument FUNCTION to it.
If FUNCTION is nil, applies `message' to it, thus printing it."
  (and (not (get-buffer-window standard-output))
219
       (let ((first-message
220
	      (cond ((special-display-p (buffer-name standard-output))
221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239
		     ;; If the help output buffer is a special display buffer,
		     ;; don't say anything about how to get rid of it.
		     ;; First of all, the user will do that with the window
		     ;; manager, not with Emacs.
		     ;; Secondly, the buffer has not been displayed yet,
		     ;; so we don't know whether its frame will be selected.
		     nil)
		    ((not (one-window-p t))
		     "Type \\[switch-to-buffer-other-window] RET to restore the other window.")
		    (pop-up-windows
		     "Type \\[delete-other-windows] to remove help window.")
		    (t
		     "Type \\[switch-to-buffer] RET to remove help window."))))
	 (funcall (or function 'message)
		  (concat
		   (if first-message
		       (substitute-command-keys first-message)
		     "")
		   (if first-message "  " "")
240 241
		   ;; If the help buffer will go in a separate frame,
		   ;; it's no use mentioning a command to scroll, so don't.
242
		   (if (special-display-p (buffer-name standard-output))
243
		       nil
244
		     (if (same-window-p (buffer-name standard-output))
245 246 247 248
			 ;; Say how to scroll this window.
			 (substitute-command-keys
			  "\\[scroll-up] to scroll the help.")
		       ;; Say how to scroll some other window.
249
		       (substitute-command-keys
250
			"\\[scroll-other-window] to scroll the help."))))))))
Richard M. Stallman's avatar
Richard M. Stallman committed
251 252 253 254

(defun describe-key (key)
  "Display documentation of the function invoked by KEY.  KEY is a string."
  (interactive "kDescribe key: ")
255 256 257 258 259 260 261 262
  ;; If this key seq ends with a down event, discard the
  ;; following click or drag event.  Otherwise that would
  ;; erase the message.
  (let ((type (aref key (1- (length key)))))
    (if (listp type) (setq type (car type)))
    (and (symbolp type)
	 (memq 'down (event-modifiers type))
	 (read-event)))
263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285
  (save-excursion
    (let ((modifiers (event-modifiers (aref key 0)))
	  window position)
      ;; For a mouse button event, go to the button it applies to
      ;; to get the right key bindings.  And go to the right place
      ;; in case the keymap depends on where you clicked.
      (if (or (memq 'click modifiers) (memq 'down modifiers)
	      (memq 'drag modifiers))
	  (setq window (posn-window (event-start (aref key 0)))
		position (posn-point (event-start (aref key 0)))))
      (if (windowp window)
	  (progn
	    (set-buffer (window-buffer window))
	    (goto-char position)))
      (let ((defn (key-binding key)))
	(if (or (null defn) (integerp defn))
	    (message "%s is undefined" (key-description key))
	  (with-output-to-temp-buffer "*Help*"
	    (princ (key-description key))
	    (if (windowp window)
		(princ " at that spot"))
	    (princ " runs the command ")
	    (prin1 defn)
286
	    (princ "\n")
287 288 289 290 291
	    (let ((doc (documentation defn)))
	      (if doc
		  (progn (terpri)
			 (princ doc))
		(princ "not documented")))
292 293 294 295
	    (save-excursion
	      (set-buffer standard-output)
	      (help-mode))
	    (print-help-return-message)))))))
Richard M. Stallman's avatar
Richard M. Stallman committed
296

297 298
(defun describe-mode ()
  "Display documentation of current major mode and minor modes.
Richard M. Stallman's avatar
Richard M. Stallman committed
299
For this to work correctly for a minor mode, the mode's indicator variable
300
\(listed in `minor-mode-alist') must also be a function whose documentation
Richard M. Stallman's avatar
Richard M. Stallman committed
301
describes the minor mode."
302
  (interactive)
Richard M. Stallman's avatar
Richard M. Stallman committed
303
  (with-output-to-temp-buffer "*Help*"
304
    (let ((minor-modes minor-mode-alist)
305
	  (first t))
306 307
      (while minor-modes
	(let* ((minor-mode (car (car minor-modes)))
308
	       (indicator (car (cdr (car minor-modes)))))
309 310 311
	  ;; Document a minor mode if it is listed in minor-mode-alist,
	  ;; bound locally in this buffer, non-nil, and has a function
	  ;; definition.
312
	  (if (and (symbol-value minor-mode)
313 314 315 316 317 318 319 320 321
		   (fboundp minor-mode))
	      (let ((pretty-minor-mode minor-mode))
		(if (string-match "-mode$" (symbol-name minor-mode))
		    (setq pretty-minor-mode
			  (capitalize
			   (substring (symbol-name minor-mode)
				      0 (match-beginning 0)))))
		(while (and indicator (symbolp indicator))
		  (setq indicator (symbol-value indicator)))
322 323 324 325
		(if first
		    (princ "The minor modes are described first,
followed by the major mode, which is described on the last page.\n\f\n"))
		(setq first nil)
326 327 328 329 330
		(princ (format "%s minor mode (%s):\n"
			       pretty-minor-mode
			       (if indicator
				   (format "indicator%s" indicator)
				 "no indicator")))
331
		(princ (documentation minor-mode))
332
		(princ "\n\f\n"))))
333
	(setq minor-modes (cdr minor-modes))))
Richard M. Stallman's avatar
Richard M. Stallman committed
334
    (princ mode-name)
335
    (princ " mode:\n")
Richard M. Stallman's avatar
Richard M. Stallman committed
336
    (princ (documentation major-mode))
337 338 339
    (save-excursion
      (set-buffer standard-output)
      (help-mode))
Richard M. Stallman's avatar
Richard M. Stallman committed
340 341 342 343 344 345 346 347 348
    (print-help-return-message)))

;; So keyboard macro definitions are documented correctly
(fset 'defining-kbd-macro (symbol-function 'start-kbd-macro))

(defun describe-distribution ()
  "Display info on how to obtain the latest version of GNU Emacs."
  (interactive)
  (find-file-read-only
Jim Blandy's avatar
Jim Blandy committed
349
   (expand-file-name "DISTRIB" data-directory)))
Richard M. Stallman's avatar
Richard M. Stallman committed
350 351 352 353 354

(defun describe-copying ()
  "Display info on how you may redistribute copies of GNU Emacs."
  (interactive)
  (find-file-read-only
Jim Blandy's avatar
Jim Blandy committed
355
   (expand-file-name "COPYING" data-directory))
Richard M. Stallman's avatar
Richard M. Stallman committed
356 357
  (goto-char (point-min)))

358 359 360 361 362 363 364
(defun describe-project ()
  "Display info on the GNU project."
  (interactive)
  (find-file-read-only
   (expand-file-name "GNU" data-directory))
  (goto-char (point-min)))

Richard M. Stallman's avatar
Richard M. Stallman committed
365 366 367 368 369 370 371 372
(defun describe-no-warranty ()
  "Display info on all the kinds of warranty Emacs does NOT have."
  (interactive)
  (describe-copying)
  (let (case-fold-search)
    (search-forward "NO WARRANTY")
    (recenter 0)))

373
(defun describe-prefix-bindings ()
374 375 376
  "Describe the bindings of the prefix used to reach this command.
The prefix described consists of all but the last event
of the key sequence that ran this command."
377
  (interactive)
378 379 380 381 382 383 384 385 386 387
  (let* ((key (this-command-keys)))
    (describe-bindings
     (if (stringp key)
	 (substring key 0 (1- (length key)))
       (let ((prefix (make-vector (1- (length key)) nil))
	     (i 0))
	 (while (< i (length prefix))
	   (aset prefix i (aref key i))
	   (setq i (1+ i)))
	 prefix)))))
388 389
;; Make C-h after a prefix, when not specifically bound, 
;; run describe-prefix-bindings.
390 391
(setq prefix-help-command 'describe-prefix-bindings)

Richard M. Stallman's avatar
Richard M. Stallman committed
392 393 394
(defun view-emacs-news ()
  "Display info on recent changes to Emacs."
  (interactive)
Jim Blandy's avatar
Jim Blandy committed
395
  (find-file-read-only (expand-file-name "NEWS" data-directory)))
Richard M. Stallman's avatar
Richard M. Stallman committed
396

397 398 399 400 401
(defun view-emacs-FAQ ()
  "Display the Emacs Frequently Asked Questions (FAQ) file."
  (interactive)
  (find-file-read-only (expand-file-name "FAQ" data-directory)))

Richard M. Stallman's avatar
Richard M. Stallman committed
402 403 404 405
(defun view-lossage ()
  "Display last 100 input keystrokes."
  (interactive)
  (with-output-to-temp-buffer "*Help*"
406 407 408 409 410 411 412 413
    (princ (mapconcat (function (lambda (key)
				  (if (or (integerp key)
					  (symbolp key)
					  (listp key))
				      (single-key-description key)
				    (prin1-to-string key nil))))
		      (recent-keys)
		      " "))
Richard M. Stallman's avatar
Richard M. Stallman committed
414 415 416 417 418
    (save-excursion
      (set-buffer standard-output)
      (goto-char (point-min))
      (while (progn (move-to-column 50) (not (eobp)))
	(search-forward " " nil t)
419 420
	(insert "\n"))
      (help-mode))
Richard M. Stallman's avatar
Richard M. Stallman committed
421 422
    (print-help-return-message)))

Richard M. Stallman's avatar
Richard M. Stallman committed
423
(defalias 'help 'help-for-help)
424
(make-help-screen help-for-help
425
  "a b c C f F C-f i I k C-k l L m n p s t v w C-c C-d C-n C-p C-w; ? for help:"
426
  "You have typed \\[help-command], the help character.  Type a Help option:
427
\(Use SPC or DEL to scroll through this text.  Type \\<help-map>\\[help-quit] to exit the Help command.)
Richard M. Stallman's avatar
Richard M. Stallman committed
428

429 430 431
a  command-apropos.  Give a substring, and see a list of commands
	(functions interactively callable) that contain
	that substring.  See also the  apropos  command.
432 433
b  describe-bindings.  Display table of all key bindings.
c  describe-key-briefly.  Type a command key sequence;
434
	it prints the function name that sequence runs.
435 436 437
C  describe-coding-system.  This describes either a specific coding system
        (if you type its name) or the coding systems currently in use
	(if you type just RET).
438
f  describe-function.  Type a function name and get documentation of it.
439 440
C-f Info-goto-emacs-command-node.  Type a function name;
	it takes you to the Info node for that command.
441
i  info. The  info  documentation reader.
442 443
I  describe-input-method.  Describe a specific input method (if you type
	its name) or the current input method (if you type just RET).
444
k  describe-key.  Type a command key sequence;
445 446 447
	it displays the full documentation.
C-k Info-goto-emacs-key-command-node.  Type a command key sequence;
	it takes you to the Info node for the command bound to that key.
448
l  view-lossage.  Shows last 100 characters you typed.
449 450 451
L  describe-language-environment.  This describes either the a
	specific language environment (if you type its name)
	or the current language environment (if you type just RET).
452
m  describe-mode.  Print documentation of current major mode,
453
	which describes the commands peculiar to it.
454 455 456 457 458
n  view-emacs-news.  Shows emacs news file.
p  finder-by-keyword. Find packages matching a given topic keyword.
s  describe-syntax.  Display contents of syntax table, plus explanations
t  help-with-tutorial.  Select the Emacs learn-by-doing tutorial.
v  describe-variable.  Type name of a variable;
459
	it displays the variable's documentation and value.
460
w  where-is.  Type command name; it prints which keystrokes
461
	invoke that command.
462 463 464 465 466 467 468 469

F  Display the frequently asked questions file.
h  Display the HELLO file which illustrates various scripts.
C-c Display Emacs copying permission (General Public License).
C-d Display Emacs ordering information.
C-n Display news of recent Emacs changes.
C-p Display information about the GNU project.
C-w Display information on absence of warranty for GNU Emacs."
470
  help-map)
Richard M. Stallman's avatar
Richard M. Stallman committed
471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486

;; Return a function which is called by the list containing point.
;; If that gives no function, return a function whose name is around point.
;; If that doesn't give a function, return nil.
(defun function-called-at-point ()
  (or (condition-case ()
	  (save-excursion
	    (save-restriction
	      (narrow-to-region (max (point-min) (- (point) 1000)) (point-max))
	      (backward-up-list 1)
	      (forward-char 1)
	      (let (obj)
		(setq obj (read (current-buffer)))
		(and (symbolp obj) (fboundp obj) obj))))
	(error nil))
      (condition-case ()
487 488 489 490 491 492 493 494 495 496 497 498
	  (let ((stab (syntax-table)))
	    (unwind-protect
		(save-excursion
		  (set-syntax-table emacs-lisp-mode-syntax-table)
		  (or (not (zerop (skip-syntax-backward "_w")))
		      (eq (char-syntax (following-char)) ?w)
		      (eq (char-syntax (following-char)) ?_)
		      (forward-sexp -1))
		  (skip-chars-forward "'")
		  (let ((obj (read (current-buffer))))
		    (and (symbolp obj) (fboundp obj) obj)))
	      (set-syntax-table stab)))
Richard M. Stallman's avatar
Richard M. Stallman committed
499 500
	(error nil))))

501 502 503 504 505 506 507 508 509
(defun describe-function-find-file (function)
  (let ((files load-history)
	file functions)
    (while files
      (if (memq function (cdr (car files)))
	  (setq file (car (car files)) files nil))
      (setq files (cdr files)))
    file))

Richard M. Stallman's avatar
Richard M. Stallman committed
510 511 512 513 514 515 516 517 518 519 520 521
(defun describe-function (function)
  "Display the full documentation of FUNCTION (a symbol)."
  (interactive
   (let ((fn (function-called-at-point))
	 (enable-recursive-minibuffers t)	     
	 val)
     (setq val (completing-read (if fn
				    (format "Describe function (default %s): " fn)
				  "Describe function: ")
				obarray 'fboundp t))
     (list (if (equal val "")
	       fn (intern val)))))
522 523 524
  (if function
      (with-output-to-temp-buffer "*Help*"
	(prin1 function)
525 526 527
	;; Use " is " instead of a colon so that
	;; it is easier to get out the function name using forward-sexp.
	(princ " is ")
528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591
	(let* ((def (symbol-function function))
	       file-name
	       (beg (if (commandp def) "an interactive " "a ")))
	  (princ (cond ((or (stringp def)
			    (vectorp def))
			"a keyboard macro")
		       ((subrp def)
			(concat beg "built-in function"))
		       ((byte-code-function-p def)
			(concat beg "compiled Lisp function"))
		       ((symbolp def)
			(format "alias for `%s'" def))
		       ((eq (car-safe def) 'lambda)
			(concat beg "Lisp function"))
		       ((eq (car-safe def) 'macro)
			"a Lisp macro")
		       ((eq (car-safe def) 'mocklisp)
			"a mocklisp function")
		       ((eq (car-safe def) 'autoload)
			(setq file-name (nth 1 def))
			(format "%s autoloaded Lisp %s"
				(if (commandp def) "an interactive" "an")
				(if (nth 4 def) "macro" "function")
				))
		       (t "")))
	  (or file-name
	      (setq file-name (describe-function-find-file function)))
	  (if file-name
	      (progn
		(princ " in `")
		;; We used to add .el to the file name,
		;; but that's completely wrong when the user used load-file.
		(princ file-name)
		(princ "'")))
	  (princ ".")
	  (terpri)
	  (let ((arglist (cond ((byte-code-function-p def)
				(car (append def nil)))
			       ((eq (car-safe def) 'lambda)
				(nth 1 def))
			       (t t))))
	    (if (listp arglist)
		(progn
		  (princ (cons function
			       (mapcar (lambda (arg)
					 (if (memq arg '(&optional &rest))
					     arg
					   (intern (upcase (symbol-name arg)))))
				       arglist)))
		  (terpri))))
	  (let ((doc (documentation function)))
	    (if doc
		(progn (terpri)
		       (princ doc))
	      (princ "not documented"))))
	(print-help-return-message)
	(save-excursion
	  (set-buffer standard-output)
	  (help-mode)
	  ;; Return the text we displayed.
	  (buffer-string)))
    (message "You didn't specify a function")))

;; We return 0 if we can't find a variable to return.
Richard M. Stallman's avatar
Richard M. Stallman committed
592 593
(defun variable-at-point ()
  (condition-case ()
594 595 596 597 598 599 600 601 602 603
      (let ((stab (syntax-table)))
	(unwind-protect
	    (save-excursion
	      (set-syntax-table emacs-lisp-mode-syntax-table)
	      (or (not (zerop (skip-syntax-backward "_w")))
		  (eq (char-syntax (following-char)) ?w)
		  (eq (char-syntax (following-char)) ?_)
		  (forward-sexp -1))
	      (skip-chars-forward "'")
	      (let ((obj (read (current-buffer))))
604 605
		(or (and (symbolp obj) (boundp obj) obj)
		    0)))
606
	  (set-syntax-table stab)))
607
    (error 0)))
Richard M. Stallman's avatar
Richard M. Stallman committed
608 609 610 611 612 613 614 615

(defun describe-variable (variable)
  "Display the full documentation of VARIABLE (a symbol).
Returns the documentation as a string, also."
  (interactive 
   (let ((v (variable-at-point))
	 (enable-recursive-minibuffers t)
	 val)
616
     (setq val (completing-read (if (symbolp v)
Richard M. Stallman's avatar
Richard M. Stallman committed
617 618 619 620 621
				    (format "Describe variable (default %s): " v)
				  "Describe variable: ")
				obarray 'boundp t))
     (list (if (equal val "")
	       v (intern val)))))
622
  (if (symbolp variable)
623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666
      (let (valvoid)
	(with-output-to-temp-buffer "*Help*"
	  (prin1 variable)
	  (if (not (boundp variable))
	      (progn
		(princ " is void")
		(terpri)
		(setq valvoid t))
	    (princ "'s value is ")
	    (terpri)
	    (pp (symbol-value variable))
	    (terpri))
	  (if (local-variable-p variable)
	      (progn
		(princ (format "Local in buffer %s; " (buffer-name)))
		(if (not (default-boundp variable))
		    (princ "globally void")
		  (princ "global value is ")
		  (terpri)
		  (pp (default-value variable)))
		(terpri)))
	  (terpri)
	  (save-current-buffer
	    (set-buffer standard-output)
	    (if (> (count-lines (point-min) (point-max)) 10)
		(progn
		  (goto-char (point-min))
		  (if valvoid
		      (forward-line 1)
		    (forward-sexp 1)
		    (delete-region (point) (progn (end-of-line) (point)))
		    (insert "'s value is shown below.\n\n")
		    (save-excursion
		      (insert "\n\nValue:"))))))
	  (princ "Documentation:")
	  (terpri)
	  (let ((doc (documentation-property variable 'variable-documentation)))
	    (princ (or doc "not documented as a variable.")))
	  (print-help-return-message)
	  (save-excursion
	    (set-buffer standard-output)
	    (help-mode)
	    ;; Return the text we displayed.
	    (buffer-string))))
667
    (message "You did not specify a variable")))
Richard M. Stallman's avatar
Richard M. Stallman committed
668

669
(defun where-is (definition &optional insert)
670
  "Print message listing key sequences that invoke specified command.
671 672
Argument is a command definition, usually a symbol with a function definition.
If INSERT (the prefix arg) is non-nil, insert the message in the buffer."
673 674 675 676 677 678 679 680 681
  (interactive
   (let ((fn (function-called-at-point))
	 (enable-recursive-minibuffers t)	     
	 val)
     (setq val (completing-read (if fn
				    (format "Where is command (default %s): " fn)
				  "Where is command: ")
				obarray 'fboundp t))
     (list (if (equal val "")
682 683
	       fn (intern val))
	   current-prefix-arg)))
684
  (let* ((keys (where-is-internal definition overriding-local-map nil nil))
685 686 687 688 689 690 691 692 693
	 (keys1 (mapconcat 'key-description keys ", "))
	 (standard-output (if insert (current-buffer) t)))
    (if insert
	(if (> (length keys1) 0)
	    (princ (format "%s (%s)" keys1 definition))
	  (princ (format "M-x %s RET" definition)))
      (if (> (length keys1) 0)
	  (princ (format "%s is on %s" definition keys1))
	(princ (format "%s is not on any key" definition)))))
694 695
  nil)

696
(defun locate-library (library &optional nosuffix path interactive-call)
697
  "Show the precise file name of Emacs library LIBRARY.
Richard M. Stallman's avatar
Richard M. Stallman committed
698 699 700
This command searches the directories in `load-path' like `M-x load-library'
to find the file that `M-x load-library RET LIBRARY RET' would load.
Optional second arg NOSUFFIX non-nil means don't add suffixes `.elc' or `.el'
701 702 703 704
to the specified name LIBRARY.

If the optional third arg PATH is specified, that list of directories
is used instead of `load-path'."
705 706 707 708 709 710
  (interactive (list (read-string "Locate library: ")
		     nil nil
		     t))
  (let (result)
    (catch 'answer
      (mapcar
711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734
       (lambda (dir)
	 (mapcar
	  (lambda (suf)
	    (let ((try (expand-file-name (concat library suf) dir)))
	      (and (file-readable-p try)
		   (null (file-directory-p try))
		   (progn
		     (setq result try)
		     (throw 'answer try)))))
	  (if nosuffix
	      '("")
	    (let ((basic '(".elc" ".el" ""))
		  (compressed '(".Z" ".gz" "")))
	      ;; If autocompression mode is on,
	      ;; consider all combinations of library suffixes
	      ;; and compression suffixes.
	      (if (rassq 'jka-compr-handler file-name-handler-alist)
		  (apply 'nconc
			 (mapcar (lambda (compelt)
				   (mapcar (lambda (baselt)
					     (concat baselt compelt))
					   basic))
				 compressed))
		basic)))))
735 736 737 738 739 740
       (or path load-path)))
    (and interactive-call
	 (if result
	     (message "Library is file %s" result)
	   (message "No library %s in search path" library)))
    result))
Eric S. Raymond's avatar
Eric S. Raymond committed
741 742

;;; help.el ends here