1 ;;; help.el --- help commands for Emacs
3 ;; Copyright (C) 1985, 1986 Free Software Foundation, Inc.
6 ;; Keywords: help, internal
8 ;; This file is part of GNU Emacs.
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)
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.
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
22 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
26 (defvar help-map (make-sparse-keymap)
27 "Keymap for characters following the Help key.")
29 (define-key global-map (char-to-string help-char) 'help-command)
30 (fset 'help-command help-map)
32 (define-key help-map (char-to-string help-char) 'help-for-help)
33 (define-key help-map "?" 'help-for-help)
35 (define-key help-map "\C-c" 'describe-copying)
36 (define-key help-map "\C-d" 'describe-distribution)
37 (define-key help-map "\C-w" 'describe-no-warranty)
38 (define-key help-map "a" 'command-apropos)
40 (define-key help-map "b" 'describe-bindings)
42 (define-key help-map "c" 'describe-key-briefly)
43 (define-key help-map "k" 'describe-key)
45 (define-key help-map "d" 'describe-function)
46 (define-key help-map "f" 'describe-function)
48 (define-key help-map "i" 'info)
49 (define-key help-map "\C-f" 'Info-goto-emacs-command-node)
50 (define-key help-map "\C-k" 'Info-goto-emacs-key-command-node)
52 (define-key help-map "l" 'view-lossage)
54 (define-key help-map "m" 'describe-mode)
56 (define-key help-map "\C-n" 'view-emacs-news)
57 (define-key help-map "n" 'view-emacs-news)
59 (define-key help-map "s" 'describe-syntax)
61 (define-key help-map "t" 'help-with-tutorial)
63 (define-key help-map "w" 'where-is)
65 (define-key help-map "v" 'describe-variable)
67 (defun help-with-tutorial ()
68 "Select the Emacs learn-by-doing tutorial."
70 (let ((file (expand-file-name "~/TUTORIAL")))
71 (delete-other-windows)
72 (if (get-file-buffer file)
73 (switch-to-buffer (get-file-buffer file))
74 (switch-to-buffer (create-file-buffer file))
75 (setq buffer-file-name file)
76 (setq default-directory (expand-file-name "~/"))
77 (setq buffer-auto-save-file-name nil)
78 (insert-file-contents (expand-file-name "TUTORIAL" data-directory))
79 (goto-char (point-min))
80 (search-forward "\n<<")
82 (delete-region (point) (progn (end-of-line) (point)))
83 (newline (- (window-height (selected-window))
84 (count-lines (point-min) (point))
86 (goto-char (point-min))
87 (set-buffer-modified-p nil))))
89 (defun describe-key-briefly (key)
90 "Print the name of the function KEY invokes. KEY is a string."
91 (interactive "kDescribe key briefly: ")
92 (let ((defn (key-binding key)))
93 (if (or (null defn) (integerp defn))
94 (message "%s is undefined" (key-description key))
95 (message "%s runs the command %s"
97 (if (symbolp defn) defn (prin1-to-string defn))))))
99 (defun print-help-return-message (&optional function)
100 "Display or return message saying how to restore windows after help command.
101 Computes a message and applies the optional argument FUNCTION to it.
102 If FUNCTION is nil, applies `message' to it, thus printing it."
103 (and (not (get-buffer-window standard-output))
104 (funcall (or function 'message)
106 (substitute-command-keys
109 "Type \\[delete-other-windows] to remove help window."
110 "Type \\[switch-to-buffer] RET to remove help window.")
111 "Type \\[switch-to-buffer-other-window] RET to restore the other window."))
112 (substitute-command-keys
113 " \\[scroll-other-window] to scroll the help.")))))
115 (defun describe-key (key)
116 "Display documentation of the function invoked by KEY. KEY is a string."
117 (interactive "kDescribe key: ")
118 (let ((defn (key-binding key)))
119 (if (or (null defn) (integerp defn))
120 (message "%s is undefined" (key-description key))
121 (with-output-to-temp-buffer "*Help*"
124 (if (documentation defn)
125 (princ (documentation defn))
126 (princ "not documented"))
127 (print-help-return-message)))))
129 (defun describe-mode (&optional minor)
130 "Display documentation of current major mode.
131 If optional MINOR is non-nil (or prefix argument is given if interactive),
132 display documentation of active minor modes as well.
133 For this to work correctly for a minor mode, the mode's indicator variable
134 (listed in `minor-mode-alist') must also be a function whose documentation
135 describes the minor mode."
137 (with-output-to-temp-buffer "*Help*"
140 (princ (documentation major-mode))
141 (let ((minor-modes minor-mode-alist)
142 (locals (buffer-local-variables)))
144 (let* ((minor-mode (car (car minor-modes)))
145 (indicator (car (cdr (car minor-modes))))
146 (local-binding (assq minor-mode locals)))
147 ;; Document a minor mode if it is listed in minor-mode-alist,
148 ;; bound locally in this buffer, non-nil, and has a function
150 (if (and local-binding
152 (fboundp minor-mode))
154 (princ (format "\n\n\n%s minor mode (indicator%s):\n"
155 minor-mode indicator))
156 (princ (documentation minor-mode)))))
157 (setq minor-modes (cdr minor-modes))))
158 (print-help-return-message)))
160 ;; So keyboard macro definitions are documented correctly
161 (fset 'defining-kbd-macro (symbol-function 'start-kbd-macro))
163 (defun describe-distribution ()
164 "Display info on how to obtain the latest version of GNU Emacs."
167 (expand-file-name "DISTRIB" data-directory)))
169 (defun describe-copying ()
170 "Display info on how you may redistribute copies of GNU Emacs."
173 (expand-file-name "COPYING" data-directory))
174 (goto-char (point-min)))
176 (defun describe-no-warranty ()
177 "Display info on all the kinds of warranty Emacs does NOT have."
180 (let (case-fold-search)
181 (search-forward "NO WARRANTY")
184 (defun view-emacs-news ()
185 "Display info on recent changes to Emacs."
187 (find-file-read-only (expand-file-name "NEWS" data-directory)))
189 (defun view-lossage ()
190 "Display last 100 input keystrokes."
192 (with-output-to-temp-buffer "*Help*"
193 (princ (key-description (recent-keys)))
195 (set-buffer standard-output)
196 (goto-char (point-min))
197 (while (progn (move-to-column 50) (not (eobp)))
198 (search-forward " " nil t)
200 (print-help-return-message)))
202 (defun help-for-help ()
203 "You have typed \\[help-for-help], the help character. Type a Help option:
205 A command-apropos. Give a substring, and see a list of commands
206 (functions interactively callable) that contain
207 that substring. See also the apropos command.
208 B describe-bindings. Display table of all key bindings.
209 C describe-key-briefly. Type a command key sequence;
210 it prints the function name that sequence runs.
211 F describe-function. Type a function name and get documentation of it.
212 I info. The info documentation reader.
213 K describe-key. Type a command key sequence;
214 it displays the full documentation.
215 L view-lossage. Shows last 100 characters you typed.
216 M describe-mode. Print documentation of current major mode,
217 which describes the commands peculiar to it.
218 N view-emacs-news. Shows emacs news file.
219 S describe-syntax. Display contents of syntax table, plus explanations
220 T help-with-tutorial. Select the Emacs learn-by-doing tutorial.
221 V describe-variable. Type name of a variable;
222 it displays the variable's documentation and value.
223 W where-is. Type command name; it prints which keystrokes
225 C-c print Emacs copying permission (General Public License).
226 C-d print Emacs ordering information.
227 C-n print news of recent Emacs changes.
228 C-w print information on absence of warranty for GNU Emacs."
230 (message (substitute-command-keys
231 "A B C F I K L M N S T V W C-c C-d C-n C-w. Type \\[help-for-help] again for more help: "))
232 (let ((char (read-char)))
233 (if (or (= char help-char) (= char ??))
234 (save-window-excursion
235 (switch-to-buffer "*Help*")
236 (delete-other-windows)
238 (insert (documentation 'help-for-help))
239 (goto-char (point-min))
240 (while (memq char (cons help-char '(?? ?\C-v ?\ ?\177 ?\M-v)))
241 (if (memq char '(?\C-v ?\ ))
243 (if (memq char '(?\177 ?\M-v))
245 (message "A B C F I K L M N S T V W C-c C-d C-n C-w%s: "
246 (if (pos-visible-in-window-p (point-max))
247 "" " or Space to scroll"))
248 (let ((cursor-in-echo-area t))
249 (setq char (read-char))))))
250 (let ((defn (cdr (assq (downcase char) (cdr help-map)))))
251 (if defn (call-interactively defn) (ding)))))
254 ;; Return a function which is called by the list containing point.
255 ;; If that gives no function, return a function whose name is around point.
256 ;; If that doesn't give a function, return nil.
257 (defun function-called-at-point ()
258 (or (condition-case ()
261 (narrow-to-region (max (point-min) (- (point) 1000)) (point-max))
265 (setq obj (read (current-buffer)))
266 (and (symbolp obj) (fboundp obj) obj))))
271 (skip-chars-forward "'")
272 (let ((obj (read (current-buffer))))
273 (and (symbolp obj) (fboundp obj) obj)))
276 (defun describe-function (function)
277 "Display the full documentation of FUNCTION (a symbol)."
279 (let ((fn (function-called-at-point))
280 (enable-recursive-minibuffers t)
282 (setq val (completing-read (if fn
283 (format "Describe function (default %s): " fn)
284 "Describe function: ")
286 (list (if (equal val "")
288 (with-output-to-temp-buffer "*Help*"
291 (let* ((def (symbol-function function))
292 (beg (if (commandp def) "an interactive " "a ")))
293 (princ (cond ((stringp def) "a keyboard macro.")
295 (concat beg "built-in function."))
296 ((compiled-function-p def)
297 (concat beg "compiled Lisp function."))
299 (format "alias for `%s'." def))
300 ((eq (car-safe def) 'lambda)
301 (concat beg "Lisp function."))
302 ((eq (car-safe def) 'macro)
304 ((eq (car-safe def) 'mocklisp)
305 "a mocklisp function.")
306 ((eq (car-safe def) 'autoload)
307 (format "%s autoloaded Lisp %s."
308 (if (commandp def) "an interactive" "an")
309 (if (nth 4 def) "macro" "function")
310 ;;; Including the file name made this line too long.
315 (if (documentation function)
316 (princ (documentation function))
317 (princ "not documented"))
318 (print-help-return-message)
319 ;; Return the text we displayed.
320 (save-excursion (set-buffer standard-output) (buffer-string))))
322 (defun variable-at-point ()
326 (skip-chars-forward "'")
327 (let ((obj (read (current-buffer))))
328 (and (symbolp obj) (boundp obj) obj)))
331 (defun describe-variable (variable)
332 "Display the full documentation of VARIABLE (a symbol).
333 Returns the documentation as a string, also."
335 (let ((v (variable-at-point))
336 (enable-recursive-minibuffers t)
338 (setq val (completing-read (if v
339 (format "Describe variable (default %s): " v)
340 "Describe variable: ")
342 (list (if (equal val "")
344 (with-output-to-temp-buffer "*Help*"
346 (princ "'s value is ")
347 (if (not (boundp variable))
349 (prin1 (symbol-value variable)))
351 (princ "Documentation:")
353 (let ((doc (documentation-property variable 'variable-documentation)))
355 (princ (substitute-command-keys doc))
356 (princ "not documented as a variable.")))
357 (print-help-return-message)
358 ;; Return the text we displayed.
359 (save-excursion (set-buffer standard-output) (buffer-string))))
361 (defun command-apropos (string)
362 "Like apropos but lists only symbols that are names of commands
363 \(interactively callable functions). Argument REGEXP is a regular expression
364 that is matched against command symbol names. Returns list of symbols and
365 documentation found."
366 (interactive "sCommand apropos (regexp): ")
368 (let ((standard-output (get-buffer-create "*Help*")))
369 (print-help-return-message 'identity))))
370 (apropos string t 'commandp)
371 (and message (message message))))
373 (defun locate-library (library &optional nosuffix)
374 "Show the full path name of Emacs library LIBRARY.
375 This command searches the directories in `load-path' like `M-x load-library'
376 to find the file that `M-x load-library RET LIBRARY RET' would load.
377 Optional second arg NOSUFFIX non-nil means don't add suffixes `.elc' or `.el'
378 to the specified name LIBRARY (a la calling `load' instead of `load-library')."
379 (interactive "sLocate library: ")
385 (let ((try (expand-file-name (concat library suf) dir)))
386 (and (file-readable-p try)
387 (null (file-directory-p try))
389 (message "Library is file %s" try)
390 (throw 'answer try)))))
391 (if nosuffix '("") '(".elc" ".el" ""))))
393 (message "No library %s in search path" library)
396 ;;; help.el ends here