1 ;;; help.el --- help commands for Emacs
3 ;; Copyright (C) 1985, 1986, 1993 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 ;; This code implements GNU Emac's on-line help system, the one invoked by
27 ;;`M-x help-for-help'.
31 ;; Get the macro make-help-screen when this is compiled,
32 ;; or run interpreted, but not when the compiled code is loaded.
33 (eval-when-compile (require 'help-macro
))
35 (defvar help-map
(make-sparse-keymap)
36 "Keymap for characters following the Help key.")
38 (define-key global-map
(char-to-string help-char
) 'help-command
)
39 (fset 'help-command help-map
)
41 (define-key help-map
(char-to-string help-char
) 'help-for-help
)
42 (define-key help-map
"?" 'help-for-help
)
44 (define-key help-map
"\C-c" 'describe-copying
)
45 (define-key help-map
"\C-d" 'describe-distribution
)
46 (define-key help-map
"\C-w" 'describe-no-warranty
)
47 (define-key help-map
"a" 'command-apropos
)
49 (define-key help-map
"b" 'describe-bindings
)
51 (define-key help-map
"c" 'describe-key-briefly
)
52 (define-key help-map
"k" 'describe-key
)
54 (define-key help-map
"d" 'describe-function
)
55 (define-key help-map
"f" 'describe-function
)
57 (define-key help-map
"i" 'info
)
58 (define-key help-map
"\C-f" 'Info-goto-emacs-command-node
)
59 (define-key help-map
"\C-k" 'Info-goto-emacs-key-command-node
)
61 (define-key help-map
"l" 'view-lossage
)
63 (define-key help-map
"m" 'describe-mode
)
65 (define-key help-map
"\C-n" 'view-emacs-news
)
66 (define-key help-map
"n" 'view-emacs-news
)
68 (define-key help-map
"p" 'finder-by-keyword
)
69 (autoload 'finder-by-keyword
"finder")
71 (define-key help-map
"s" 'describe-syntax
)
73 (define-key help-map
"t" 'help-with-tutorial
)
75 (define-key help-map
"w" 'where-is
)
77 (define-key help-map
"v" 'describe-variable
)
79 (defun help-with-tutorial ()
80 "Select the Emacs learn-by-doing tutorial."
82 (let ((file (expand-file-name "~/TUTORIAL")))
83 (delete-other-windows)
84 (if (get-file-buffer file
)
85 (switch-to-buffer (get-file-buffer file
))
86 (switch-to-buffer (create-file-buffer file
))
87 (setq buffer-file-name file
)
88 (setq default-directory
(expand-file-name "~/"))
89 (setq buffer-auto-save-file-name nil
)
90 (insert-file-contents (expand-file-name "TUTORIAL" data-directory
))
91 (goto-char (point-min))
92 (search-forward "\n<<")
94 (delete-region (point) (progn (end-of-line) (point)))
95 (newline (- (window-height (selected-window))
96 (count-lines (point-min) (point))
98 (goto-char (point-min))
99 (set-buffer-modified-p nil
))))
101 (defun describe-key-briefly (key)
102 "Print the name of the function KEY invokes. KEY is a string."
103 (interactive "kDescribe key briefly: ")
104 ;; If this key seq ends with a down event, discard the
105 ;; following click or drag event. Otherwise that would
106 ;; erase the message.
107 (let ((type (aref key
(1- (length key
)))))
108 (if (listp type
) (setq type
(car type
)))
110 (memq 'down
(event-modifiers type
))
111 (setq foo
(read-event))))
112 (let ((defn (key-binding key
)))
113 (if (or (null defn
) (integerp defn
))
114 (message "%s is undefined" (key-description key
))
115 (message "%s runs the command %s"
116 (key-description key
)
117 (if (symbolp defn
) defn
(prin1-to-string defn
))))))
119 (defun print-help-return-message (&optional function
)
120 "Display or return message saying how to restore windows after help command.
121 Computes a message and applies the optional argument FUNCTION to it.
122 If FUNCTION is nil, applies `message' to it, thus printing it."
123 (and (not (get-buffer-window standard-output
))
124 (funcall (or function
'message
)
126 (substitute-command-keys
129 "Type \\[delete-other-windows] to remove help window."
130 "Type \\[switch-to-buffer] RET to remove help window.")
131 "Type \\[switch-to-buffer-other-window] RET to restore the other window."))
132 (substitute-command-keys
133 " \\[scroll-other-window] to scroll the help.")))))
135 (defun describe-key (key)
136 "Display documentation of the function invoked by KEY. KEY is a string."
137 (interactive "kDescribe key: ")
138 ;; If this key seq ends with a down event, discard the
139 ;; following click or drag event. Otherwise that would
140 ;; erase the message.
141 (let ((type (aref key
(1- (length key
)))))
142 (if (listp type
) (setq type
(car type
)))
144 (memq 'down
(event-modifiers type
))
146 (let ((defn (key-binding key
)))
147 (if (or (null defn
) (integerp defn
))
148 (message "%s is undefined" (key-description key
))
149 (with-output-to-temp-buffer "*Help*"
152 (if (documentation defn
)
153 (princ (documentation defn
))
154 (princ "not documented"))
155 (print-help-return-message)))))
157 (defun describe-mode (&optional minor
)
158 "Display documentation of current major mode.
159 If optional MINOR is non-nil (or prefix argument is given if interactive),
160 display documentation of active minor modes as well.
161 For this to work correctly for a minor mode, the mode's indicator variable
162 (listed in `minor-mode-alist') must also be a function whose documentation
163 describes the minor mode."
165 (with-output-to-temp-buffer "*Help*"
168 (princ (documentation major-mode
))
169 (let ((minor-modes minor-mode-alist
)
170 (locals (buffer-local-variables)))
172 (let* ((minor-mode (car (car minor-modes
)))
173 (indicator (car (cdr (car minor-modes
))))
174 (local-binding (assq minor-mode locals
)))
175 ;; Document a minor mode if it is listed in minor-mode-alist,
176 ;; bound locally in this buffer, non-nil, and has a function
178 (if (and local-binding
180 (fboundp minor-mode
))
182 (princ (format "\n\n\n%s minor mode (indicator%s):\n"
183 minor-mode indicator
))
184 (princ (documentation minor-mode
)))))
185 (setq minor-modes
(cdr minor-modes
))))
186 (print-help-return-message)))
188 ;; So keyboard macro definitions are documented correctly
189 (fset 'defining-kbd-macro
(symbol-function 'start-kbd-macro
))
191 (defun describe-distribution ()
192 "Display info on how to obtain the latest version of GNU Emacs."
195 (expand-file-name "DISTRIB" data-directory
)))
197 (defun describe-copying ()
198 "Display info on how you may redistribute copies of GNU Emacs."
201 (expand-file-name "COPYING" data-directory
))
202 (goto-char (point-min)))
204 (defun describe-no-warranty ()
205 "Display info on all the kinds of warranty Emacs does NOT have."
208 (let (case-fold-search)
209 (search-forward "NO WARRANTY")
212 (defun view-emacs-news ()
213 "Display info on recent changes to Emacs."
215 (find-file-read-only (expand-file-name "NEWS" data-directory
)))
217 (defun view-lossage ()
218 "Display last 100 input keystrokes."
220 (with-output-to-temp-buffer "*Help*"
221 (princ (key-description (recent-keys)))
223 (set-buffer standard-output
)
224 (goto-char (point-min))
225 (while (progn (move-to-column 50) (not (eobp)))
226 (search-forward " " nil t
)
228 (print-help-return-message)))
230 (make-help-screen help-for-help
231 "a b c f i k l m n p s t v w C-c C-d C-n C-w. Type \\[help-for-help] again for more help: "
232 "You have typed \\[help-for-help], the help character. Type a Help option:
234 a command-apropos. Give a substring, and see a list of commands
235 (functions interactively callable) that contain
236 that substring. See also the apropos command.
237 b describe-bindings. Display table of all key bindings.
238 c describe-key-briefly. Type a command key sequence;
239 it prints the function name that sequence runs.
240 f describe-function. Type a function name and get documentation of it.
241 i info. The info documentation reader.
242 k describe-key. Type a command key sequence;
243 it displays the full documentation.
244 l view-lossage. Shows last 100 characters you typed.
245 m describe-mode. Print documentation of current major mode,
246 which describes the commands peculiar to it.
247 n view-emacs-news. Shows emacs news file.
248 p finder-by-keyword. Find packages matching a given topic keyword.
249 s describe-syntax. Display contents of syntax table, plus explanations
250 t help-with-tutorial. Select the Emacs learn-by-doing tutorial.
251 v describe-variable. Type name of a variable;
252 it displays the variable's documentation and value.
253 w where-is. Type command name; it prints which keystrokes
255 C-c print Emacs copying permission (General Public License).
256 C-d print Emacs ordering information.
257 C-n print news of recent Emacs changes.
258 C-w print information on absence of warranty for GNU Emacs."
261 ;; Return a function which is called by the list containing point.
262 ;; If that gives no function, return a function whose name is around point.
263 ;; If that doesn't give a function, return nil.
264 (defun function-called-at-point ()
265 (or (condition-case ()
268 (narrow-to-region (max (point-min) (- (point) 1000)) (point-max))
272 (setq obj
(read (current-buffer)))
273 (and (symbolp obj
) (fboundp obj
) obj
))))
278 (skip-chars-forward "'")
279 (let ((obj (read (current-buffer))))
280 (and (symbolp obj
) (fboundp obj
) obj
)))
283 (defun describe-function (function)
284 "Display the full documentation of FUNCTION (a symbol)."
286 (let ((fn (function-called-at-point))
287 (enable-recursive-minibuffers t
)
289 (setq val
(completing-read (if fn
290 (format "Describe function (default %s): " fn
)
291 "Describe function: ")
293 (list (if (equal val
"")
295 (with-output-to-temp-buffer "*Help*"
298 (let* ((def (symbol-function function
))
299 (beg (if (commandp def
) "an interactive " "a ")))
300 (princ (cond ((or (stringp def
)
304 (concat beg
"built-in function."))
305 ((byte-code-function-p def
)
306 (concat beg
"compiled Lisp function."))
308 (format "alias for `%s'." def
))
309 ((eq (car-safe def
) 'lambda
)
310 (concat beg
"Lisp function."))
311 ((eq (car-safe def
) 'macro
)
313 ((eq (car-safe def
) 'mocklisp
)
314 "a mocklisp function.")
315 ((eq (car-safe def
) 'autoload
)
316 (format "%s autoloaded Lisp %s."
317 (if (commandp def
) "an interactive" "an")
318 (if (nth 4 def
) "macro" "function")
319 ;;; Including the file name made this line too long.
324 (let ((arglist (cond ((byte-code-function-p def
)
325 (car (append def nil
)))
326 ((eq (car-safe def
) 'lambda
)
331 (princ (cons function
332 (mapcar (lambda (arg)
333 (if (memq arg
'(&optional
&rest
))
335 (intern (upcase (symbol-name arg
)))))
338 (if (documentation function
)
340 (princ (documentation function
)))
341 (princ "not documented"))
343 (print-help-return-message)
344 ;; Return the text we displayed.
345 (save-excursion (set-buffer standard-output
) (buffer-string))))
347 (defun variable-at-point ()
351 (skip-chars-forward "'")
352 (let ((obj (read (current-buffer))))
353 (and (symbolp obj
) (boundp obj
) obj
)))
356 (defun describe-variable (variable)
357 "Display the full documentation of VARIABLE (a symbol).
358 Returns the documentation as a string, also."
360 (let ((v (variable-at-point))
361 (enable-recursive-minibuffers t
)
363 (setq val
(completing-read (if v
364 (format "Describe variable (default %s): " v
)
365 "Describe variable: ")
367 (list (if (equal val
"")
369 (with-output-to-temp-buffer "*Help*"
371 (princ "'s value is ")
372 (if (not (boundp variable
))
374 (prin1 (symbol-value variable
)))
376 (princ "Documentation:")
378 (let ((doc (documentation-property variable
'variable-documentation
)))
380 (princ (substitute-command-keys doc
))
381 (princ "not documented as a variable.")))
382 (print-help-return-message)
383 ;; Return the text we displayed.
384 (save-excursion (set-buffer standard-output
) (buffer-string))))
386 (defun command-apropos (string)
387 "Like apropos but lists only symbols that are names of commands
388 \(interactively callable functions). Argument REGEXP is a regular expression
389 that is matched against command symbol names. Returns list of symbols and
390 documentation found."
391 (interactive "sCommand apropos (regexp): ")
393 (let ((standard-output (get-buffer-create "*Help*")))
394 (print-help-return-message 'identity
))))
395 (if (apropos string t
'commandp
)
396 (and message
(message message
)))))
398 (defun locate-library (library &optional nosuffix
)
399 "Show the full path name of Emacs library LIBRARY.
400 This command searches the directories in `load-path' like `M-x load-library'
401 to find the file that `M-x load-library RET LIBRARY RET' would load.
402 Optional second arg NOSUFFIX non-nil means don't add suffixes `.elc' or `.el'
403 to the specified name LIBRARY (a la calling `load' instead of `load-library')."
404 (interactive "sLocate library: ")
410 (let ((try (expand-file-name (concat library suf
) dir
)))
411 (and (file-readable-p try
)
412 (null (file-directory-p try
))
414 (message "Library is file %s" try
)
415 (throw 'answer try
)))))
416 (if nosuffix
'("") '(".elc" ".el" ""))))
418 (message "No library %s in search path" library
)
421 ;;; help.el ends here