1 ;;; help-fns.el --- Complex help functions
3 ;; Copyright (C) 1985, 1986, 1993, 1994, 1998, 1999, 2000, 2001, 2002
4 ;; Free Software Foundation, Inc.
7 ;; Keywords: help, internal
9 ;; This file is part of GNU Emacs.
11 ;; GNU Emacs is free software; you can redistribute it and/or modify
12 ;; it under the terms of the GNU General Public License as published by
13 ;; the Free Software Foundation; either version 2, or (at your option)
16 ;; GNU Emacs is distributed in the hope that it will be useful,
17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 ;; GNU General Public License for more details.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with GNU Emacs; see the file COPYING. If not, write to the
23 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
24 ;; Boston, MA 02111-1307, USA.
28 ;; This file contains those help commands which are complicated, and
29 ;; which may not be used in every session. For example
30 ;; `describe-function' will probably be heavily used when doing elisp
31 ;; programming, but not if just editing C files. Simpler help commands
40 (defun help-with-tutorial (&optional arg)
41 "Select the Emacs learn-by-doing tutorial.
42 If there is a tutorial version written in the language
43 of the selected language environment, that version is used.
44 If there's no tutorial in that language, `TUTORIAL' is selected.
45 With ARG, you are asked to choose which language."
48 (let ((minibuffer-setup-hook minibuffer-setup-hook))
49 (add-hook 'minibuffer-setup-hook
50 'minibuffer-completion-help)
51 (read-language-name 'tutorial "Language: " "English"))
52 (if (get-language-info current-language-environment 'tutorial)
53 current-language-environment
56 (setq filename (get-language-info lang 'tutorial))
57 (setq file (expand-file-name (concat "~/" filename)))
58 (delete-other-windows)
59 (if (get-file-buffer file)
60 (switch-to-buffer (get-file-buffer file))
61 (switch-to-buffer (create-file-buffer file))
62 (setq buffer-file-name file)
63 (setq default-directory (expand-file-name "~/"))
64 (setq buffer-auto-save-file-name nil)
65 (insert-file-contents (expand-file-name filename data-directory))
66 (goto-char (point-min))
67 (search-forward "\n<<")
69 ;; Convert the <<...>> line to the proper [...] line,
70 ;; or just delete the <<...>> line if a [...] line follows.
71 (cond ((save-excursion
74 (delete-region (point) (progn (forward-line 1) (point))))
75 ((looking-at "<<Blank lines inserted.*>>")
76 (replace-match "[Middle of page left blank for didactic purposes. Text continues below]"))
83 (let ((n (- (window-height (selected-window))
84 (count-lines (point-min) (point))
88 ;; For a short gap, we don't need the [...] line,
90 (delete-region (point) (progn (end-of-line) (point)))
92 ;; Some people get confused by the large gap.
95 ;; Skip the [...] line (don't delete it).
97 (newline (- n (/ n 2)))))
98 (goto-char (point-min))
99 (set-buffer-modified-p nil))))
102 (defun locate-library (library &optional nosuffix path interactive-call)
103 "Show the precise file name of Emacs library LIBRARY.
104 This command searches the directories in `load-path' like `\\[load-library]'
105 to find the file that `\\[load-library] RET LIBRARY RET' would load.
106 Optional second arg NOSUFFIX non-nil means don't add suffixes `load-suffixes'
107 to the specified name LIBRARY.
109 If the optional third arg PATH is specified, that list of directories
110 is used instead of `load-path'.
112 When called from a program, the file name is normaly returned as a
113 string. When run interactively, the argument INTERACTIVE-CALL is t,
114 and the file name is displayed in the echo area."
115 (interactive (list (completing-read "Locate library: "
116 'locate-file-completion
117 (cons load-path load-suffixes))
120 (let ((file (locate-file library
122 (append (unless nosuffix load-suffixes) '("")))))
125 (message "Library is file %s" (abbreviate-file-name file))
126 (message "No library %s in search path" library)))
133 (defun describe-function (function)
134 "Display the full documentation of FUNCTION (a symbol)."
136 (let ((fn (function-called-at-point))
137 (enable-recursive-minibuffers t)
139 (setq val (completing-read (if fn
140 (format "Describe function (default %s): " fn)
141 "Describe function: ")
142 obarray 'fboundp t nil nil (symbol-name fn)))
143 (list (if (equal val "")
146 (message "You didn't specify a function")
147 (help-setup-xref (list #'describe-function function) (interactive-p))
149 (with-output-to-temp-buffer (help-buffer)
151 ;; Use " is " instead of a colon so that
152 ;; it is easier to get out the function name using forward-sexp.
154 (describe-function-1 function)
155 (print-help-return-message)
156 (with-current-buffer standard-output
157 ;; Return the text we displayed.
160 (defun help-split-fundoc (doc def)
161 "Split a function docstring DOC into the actual doc and the usage info.
162 Return (USAGE . DOC) or nil if there's no usage info.
163 DEF is the function whose usage we're looking for in DOC."
164 ;; Functions can get the calling sequence at the end of the doc string.
165 ;; In cases where `function' has been fset to a subr we can't search for
166 ;; function's name in the doc string so we use `fn' as the anonymous
167 ;; function name instead.
168 (when (and doc (string-match "\n\n(fn\\(\\( .*\\)?)\\)\\'" doc))
169 (cons (format "(%s%s"
170 ;; Replace `fn' with the actual function name.
171 (if (consp def) "anonymous" def)
172 (match-string 1 doc))
173 (substring doc 0 (match-beginning 0)))))
175 (defun help-add-fundoc-usage (doc arglist)
176 "Add the usage info to the docstring DOC.
177 If DOC already has a usage info, then just return DOC unchanged.
178 The usage info is built from ARGLIST. DOC can be nil.
179 ARGLIST can also be t or a string of the form \"(fun ARG1 ARG2 ...)\"."
180 (unless (stringp doc) (setq doc "Not documented"))
181 (if (or (string-match "\n\n(fn\\(\\( .*\\)?)\\)\\'" doc) (eq arglist t))
184 (if (string-match "\n?\n\\'" doc)
185 (if (< (- (match-end 0) (match-beginning 0)) 2) "\n" "")
187 (if (and (stringp arglist)
188 (string-match "\\`([^ ]+\\(.*\\))\\'" arglist))
189 (concat "(fn" (match-string 1 arglist) ")")
190 (help-make-usage 'fn arglist)))))
192 (defun help-function-arglist (def)
193 ;; Handle symbols aliased to other symbols.
194 (if (and (symbolp def) (fboundp def)) (setq def (indirect-function def)))
195 ;; If definition is a macro, find the function inside it.
196 (if (eq (car-safe def) 'macro) (setq def (cdr def)))
198 ((byte-code-function-p def) (aref def 0))
199 ((eq (car-safe def) 'lambda) (nth 1 def))
200 ((and (eq (car-safe def) 'autoload) (not (eq (nth 4 def) 'keymap)))
201 "[Arg list not available until function definition is loaded.]")
204 (defun help-make-usage (function arglist)
205 (cons (if (symbolp function) function 'anonymous)
206 (mapcar (lambda (arg)
207 (if (not (symbolp arg))
208 (if (and (consp arg) (symbolp (car arg)))
209 ;; CL style default values for optional args.
210 (cons (intern (upcase (symbol-name (car arg))))
213 (let ((name (symbol-name arg)))
214 (if (string-match "\\`&" name) arg
215 (intern (upcase name))))))
219 (defun describe-function-1 (function)
220 (let* ((def (if (symbolp function)
221 (symbol-function function)
224 (beg (if (commandp def) "an interactive " "a ")))
226 (cond ((or (stringp def)
230 (if (eq 'unevalled (cdr (subr-arity def)))
231 (concat beg "special form")
232 (concat beg "built-in function")))
233 ((byte-code-function-p def)
234 (concat beg "compiled Lisp function"))
236 (while (symbolp (symbol-function def))
237 (setq def (symbol-function def)))
238 (format "an alias for `%s'" def))
239 ((eq (car-safe def) 'lambda)
240 (concat beg "Lisp function"))
241 ((eq (car-safe def) 'macro)
243 ((eq (car-safe def) 'autoload)
244 (setq file-name (nth 1 def))
245 (format "%s autoloaded %s"
246 (if (commandp def) "an interactive" "an")
247 (if (eq (nth 4 def) 'keymap) "keymap"
248 (if (nth 4 def) "Lisp macro" "Lisp function"))
252 (elts (cdr-safe def)))
254 (if (char-table-p (car-safe elts))
257 (setq elts (cdr-safe elts)))
263 (with-current-buffer standard-output
266 (if (re-search-backward "alias for `\\([^`']+\\)'" nil t)
267 (help-xref-button 1 'help-function def)))))
269 (setq file-name (symbol-file function)))
270 (when (equal file-name "loaddefs.el")
271 ;; Find the real def site of the preloaded function.
272 ;; This is necessary only for defaliases.
275 (find-function-search-for-symbol function nil "loaddefs.el")
278 (with-current-buffer (car location)
279 (goto-char (cdr location))
280 (when (re-search-backward
281 "^;;; Generated autoloads from \\(.*\\)" nil t)
282 (setq file-name (match-string 1)))))))
286 ;; We used to add .el to the file name,
287 ;; but that's completely wrong when the user used load-file.
290 ;; Make a hyperlink to the library.
291 (with-current-buffer standard-output
293 (re-search-backward "`\\([^`']+\\)'" nil t)
294 (help-xref-button 1 'help-function-def function file-name)))))
297 (when (commandp function)
298 (let* ((remapped (command-remapping function))
299 (keys (where-is-internal
300 (or remapped function) overriding-local-map nil nil)))
302 (princ "It is remapped to `")
303 (princ (symbol-name remapped))
306 (princ (if remapped " which is bound to " "It is bound to "))
307 ;; FIXME: This list can be very long (f.ex. for self-insert-command).
308 (princ (mapconcat 'key-description keys ", ")))
309 (when (or remapped keys)
312 (let* ((arglist (help-function-arglist def))
313 (doc (documentation function))
314 (usage (help-split-fundoc doc function)))
315 ;; If definition is a keymap, skip arglist note.
316 (unless (keymapp def)
318 (usage (setq doc (cdr usage)) (car usage))
319 ((listp arglist) (help-make-usage function arglist))
320 ((stringp arglist) arglist)
321 ;; Maybe the arglist is in the docstring of the alias.
322 ((let ((fun function))
323 (while (and (symbolp fun)
324 (setq fun (symbol-function fun))
325 (not (setq usage (help-split-fundoc
332 (format "\nMacro: %s" (format-kbd-macro def)))
333 (t "[Missing arglist. Please make a bug report.]")))
336 ;; function might be a lambda construct.
338 (get function 'byte-obsolete-info))))
341 (princ "This function is obsolete")
342 (if (nth 2 obsolete) (princ (format " since %s" (nth 2 obsolete))))
344 (princ (if (stringp (car obsolete)) (car obsolete)
345 (format "use `%s' instead." (car obsolete))))
348 (princ (or doc "Not documented.")))))
354 (defun variable-at-point ()
355 "Return the bound variable symbol found around point.
356 Return 0 if there is no such symbol."
358 (with-syntax-table emacs-lisp-mode-syntax-table
360 (or (not (zerop (skip-syntax-backward "_w")))
361 (eq (char-syntax (following-char)) ?w)
362 (eq (char-syntax (following-char)) ?_)
364 (skip-chars-forward "'")
365 (let ((obj (read (current-buffer))))
366 (or (and (symbolp obj) (boundp obj) obj)
371 (defun describe-variable (variable &optional buffer)
372 "Display the full documentation of VARIABLE (a symbol).
373 Returns the documentation as a string, also.
374 If VARIABLE has a buffer-local value in BUFFER (default to the current buffer),
375 it is displayed along with the global value."
377 (let ((v (variable-at-point))
378 (enable-recursive-minibuffers t)
380 (setq val (completing-read (if (symbolp v)
382 "Describe variable (default %s): " v)
383 "Describe variable: ")
384 obarray 'boundp t nil nil
385 (if (symbolp v) (symbol-name v))))
386 (list (if (equal val "")
388 (unless (buffer-live-p buffer) (setq buffer (current-buffer)))
389 (if (not (symbolp variable))
390 (message "You did not specify a variable")
392 (let* ((valvoid (not (with-current-buffer buffer (boundp variable))))
393 ;; Extract the value before setting up the output buffer,
394 ;; in case `buffer' *is* the output buffer.
395 (val (unless valvoid (buffer-local-value variable buffer))))
396 (help-setup-xref (list #'describe-variable variable buffer)
398 (with-output-to-temp-buffer (help-buffer)
399 (with-current-buffer buffer
403 (with-current-buffer standard-output
404 (princ "'s value is ")
406 (let ((from (point)))
408 (help-xref-on-pp from (point))
409 (if (< (point) (+ from 20))
410 (delete-region (1- from) from)))))
412 (when (local-variable-p variable)
413 (princ (format "Local in buffer %s; " (buffer-name)))
414 (if (not (default-boundp variable))
415 (princ "globally void")
416 (let ((val (default-value variable)))
417 (with-current-buffer standard-output
418 (princ "global value is ")
420 ;; Fixme: pp can take an age if you happen to
421 ;; ask for a very large expression. We should
422 ;; probably print it raw once and check it's a
423 ;; sensible size before prettyprinting. -- fx
424 (let ((from (point)))
426 (help-xref-on-pp from (point))
427 (if (< (point) (+ from 20))
428 (delete-region (1- from) from))))))
431 (with-current-buffer standard-output
432 (when (> (count-lines (point-min) (point-max)) 10)
433 ;; Note that setting the syntax table like below
434 ;; makes forward-sexp move over a `'s' at the end
436 (set-syntax-table emacs-lisp-mode-syntax-table)
437 (goto-char (point-min))
441 (delete-region (point) (progn (end-of-line) (point)))
442 (insert " value is shown below.\n\n")
444 (insert "\n\nValue:"))))
445 ;; Add a note for variables that have been make-var-buffer-local.
446 (when (and (local-variable-if-set-p variable)
447 (or (not (local-variable-p variable))
449 (local-variable-if-set-p variable))))
452 (insert "Automatically becomes buffer-local when set in any fashion.\n"))))
453 ;; Mention if it's an alias
454 (let* ((alias (condition-case nil
455 (indirect-variable variable)
457 (obsolete (get variable 'byte-obsolete-variable))
458 (doc (or (documentation-property variable 'variable-documentation)
459 (documentation-property alias 'variable-documentation))))
460 (unless (eq alias variable)
461 (princ (format "This variable is an alias for `%s'." alias))
465 (princ "This variable is obsolete")
466 (if (cdr obsolete) (princ (format " since %s" (cdr obsolete))))
468 (princ (if (stringp (car obsolete)) (car obsolete)
469 (format "use `%s' instead." (car obsolete))))
472 (princ (or doc "Not documented as a variable.")))
473 ;; Make a link to customize if this variable can be customized.
474 (if (custom-variable-p variable)
475 (let ((customize-label "customize"))
478 (princ (concat "You can " customize-label " this variable."))
479 (with-current-buffer standard-output
482 (concat "\\(" customize-label "\\)") nil t)
483 (help-xref-button 1 'help-customize-variable variable)))))
484 ;; Make a hyperlink to the library if appropriate. (Don't
485 ;; change the format of the buffer's initial line in case
486 ;; anything expects the current format.)
487 (let ((file-name (symbol-file (cons 'defvar variable))))
488 (when (equal file-name "loaddefs.el")
489 ;; Find the real def site of the preloaded variable.
492 (find-variable-noselect variable file-name)
495 (with-current-buffer (car location)
496 (goto-char (cdr location))
497 (when (re-search-backward
498 "^;;; Generated autoloads from \\(.*\\)" nil t)
499 (setq file-name (match-string 1)))))))
501 (princ "\n\nDefined in `")
504 (with-current-buffer standard-output
506 (re-search-backward "`\\([^`']+\\)'" nil t)
507 (help-xref-button 1 'help-variable-def
508 variable file-name)))))
510 (print-help-return-message)
512 (set-buffer standard-output)
513 ;; Return the text we displayed.
514 (buffer-string))))))))
518 (defun describe-syntax (&optional buffer)
519 "Describe the syntax specifications in the syntax table of BUFFER.
520 The descriptions are inserted in a help buffer, which is then displayed.
521 BUFFER defaults to the current buffer."
523 (setq buffer (or buffer (current-buffer)))
524 (help-setup-xref (list #'describe-syntax buffer) (interactive-p))
525 (with-output-to-temp-buffer (help-buffer)
526 (let ((table (with-current-buffer buffer (syntax-table))))
527 (with-current-buffer standard-output
528 (describe-vector table 'internal-describe-syntax-value)
529 (while (setq table (char-table-parent table))
530 (insert "\nThe parent syntax table is:")
531 (describe-vector table 'internal-describe-syntax-value))))))
533 (defun help-describe-category-set (value)
535 ((null value) "default")
536 ((char-table-p value) "deeper char-table ...")
537 (t (condition-case err
538 (category-set-mnemonics value)
539 (error "invalid"))))))
542 (defun describe-categories (&optional buffer)
543 "Describe the category specifications in the current category table.
544 The descriptions are inserted in a buffer, which is then displayed."
546 (setq buffer (or buffer (current-buffer)))
547 (help-setup-xref (list #'describe-categories buffer) (interactive-p))
548 (with-output-to-temp-buffer (help-buffer)
549 (let ((table (with-current-buffer buffer (category-table))))
550 (with-current-buffer standard-output
551 (describe-vector table 'help-describe-category-set)
552 (let ((docs (char-table-extra-slot table 0)))
553 (if (or (not (vectorp docs)) (/= (length docs) 95))
554 (insert "Invalid first extra slot in this char table\n")
555 (insert "Meanings of mnemonic characters are:\n")
557 (let ((elt (aref docs i)))
559 (insert (+ i ?\ ) ": " elt "\n"))))
560 (while (setq table (char-table-parent table))
561 (insert "\nThe parent category table is:")
562 (describe-vector table 'help-describe-category-set))))))))
566 ;;; help-fns.el ends here