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emacs/lisp/help-fns.el

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;;; help-fns.el --- Complex help functions
;; Copyright (C) 1985, 1986, 1993, 1994, 1998, 1999, 2000, 2001, 2002
;; Free Software Foundation, Inc.
;; Maintainer: FSF
;; Keywords: help, internal
;; 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
;; the Free Software Foundation; either version 2, or (at your option)
;; 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
;; 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.
;;; Commentary:
;; This file contains those help commands which are complicated, and
;; which may not be used in every session. For example
;; `describe-function' will probably be heavily used when doing elisp
;; programming, but not if just editing C files. Simpler help commands
;; are in help.el
;;; Code:
(require 'help-mode)
;;;###autoload
(defun help-with-tutorial (&optional arg)
"Select the Emacs learn-by-doing tutorial.
If there is a tutorial version written in the language
of the selected language environment, that version is used.
If there's no tutorial in that language, `TUTORIAL' is selected.
With ARG, you are asked to choose which language."
(interactive "P")
(let ((lang (if arg
(let ((minibuffer-setup-hook minibuffer-setup-hook))
(add-hook 'minibuffer-setup-hook
'minibuffer-completion-help)
(read-language-name 'tutorial "Language: " "English"))
(if (get-language-info current-language-environment 'tutorial)
current-language-environment
"English")))
file filename)
(setq filename (get-language-info lang 'tutorial))
(setq file (expand-file-name (concat "~/" filename)))
(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 "~/"))
(setq buffer-auto-save-file-name nil)
(insert-file-contents (expand-file-name filename data-directory))
(goto-char (point-min))
(search-forward "\n<<")
(beginning-of-line)
;; Convert the <<...>> line to the proper [...] line,
;; or just delete the <<...>> line if a [...] line follows.
(cond ((save-excursion
(forward-line 1)
(looking-at "\\["))
(delete-region (point) (progn (forward-line 1) (point))))
((looking-at "<<Blank lines inserted.*>>")
(replace-match "[Middle of page left blank for didactic purposes. Text continues below]"))
(t
(looking-at "<<")
(replace-match "[")
(search-forward ">>")
(replace-match "]")))
(beginning-of-line)
(let ((n (- (window-height (selected-window))
(count-lines (point-min) (point))
6)))
(if (< n 8)
(progn
;; For a short gap, we don't need the [...] line,
;; so delete it.
(delete-region (point) (progn (end-of-line) (point)))
(newline n))
;; Some people get confused by the large gap.
(newline (/ n 2))
;; Skip the [...] line (don't delete it).
(forward-line 1)
(newline (- n (/ n 2)))))
(goto-char (point-min))
(set-buffer-modified-p nil))))
;;;###autoload
(defun locate-library (library &optional nosuffix path interactive-call)
"Show the precise file name of Emacs library LIBRARY.
This command searches the directories in `load-path' like `\\[load-library]'
to find the file that `\\[load-library] RET LIBRARY RET' would load.
Optional second arg NOSUFFIX non-nil means don't add suffixes `load-suffixes'
to the specified name LIBRARY.
If the optional third arg PATH is specified, that list of directories
is used instead of `load-path'.
When called from a program, the file name is normaly returned as a
string. When run interactively, the argument INTERACTIVE-CALL is t,
and the file name is displayed in the echo area."
(interactive (list (completing-read "Locate library: "
'locate-file-completion
(cons load-path load-suffixes))
nil nil
t))
(let ((file (locate-file library
(or path load-path)
(append (unless nosuffix load-suffixes) '("")))))
(if interactive-call
(if file
(message "Library is file %s" (abbreviate-file-name file))
(message "No library %s in search path" library)))
file))
;; Functions
;;;###autoload
(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 nil nil (symbol-name fn)))
(list (if (equal val "")
fn (intern val)))))
(if (null function)
(message "You didn't specify a function")
(help-setup-xref (list #'describe-function function) (interactive-p))
(save-excursion
(with-output-to-temp-buffer (help-buffer)
(prin1 function)
;; Use " is " instead of a colon so that
;; it is easier to get out the function name using forward-sexp.
(princ " is ")
(describe-function-1 function)
(print-help-return-message)
(with-current-buffer standard-output
;; Return the text we displayed.
(buffer-string))))))
(defun help-split-fundoc (doc def)
"Split a function docstring DOC into the actual doc and the usage info.
Return (USAGE . DOC) or nil if there's no usage info.
DEF is the function whose usage we're looking for in DOC."
;; Functions can get the calling sequence at the end of the doc string.
;; In cases where `function' has been fset to a subr we can't search for
;; function's name in the doc string so we use `fn' as the anonymous
;; function name instead.
(when (and doc (string-match "\n\n(fn\\(\\( .*\\)?)\\)\\'" doc))
(cons (format "(%s%s"
;; Replace `fn' with the actual function name.
(if (consp def) "anonymous" def)
(match-string 1 doc))
(substring doc 0 (match-beginning 0)))))
(defun help-add-fundoc-usage (doc arglist)
"Add the usage info to the docstring DOC.
If DOC already has a usage info, then just return DOC unchanged.
The usage info is built from ARGLIST. DOC can be nil."
(unless (stringp doc) (setq doc "Not documented"))
(if (string-match "\n\n(fn\\(\\( .*\\)?)\\)\\'" doc)
doc
(format "%s%s%s" doc
(if (string-match "\n?\n\\'" doc)
(if (< (- (match-end 0) (match-beginning 0)) 2) "\n")
"\n\n")
(help-make-usage 'fn arglist))))
(defun help-function-arglist (def)
;; Handle symbols aliased to other symbols.
(if (and (symbolp def) (fboundp def)) (setq def (indirect-function def)))
;; If definition is a macro, find the function inside it.
(if (eq (car-safe def) 'macro) (setq def (cdr def)))
(cond
((byte-code-function-p def) (aref def 0))
((eq (car-safe def) 'lambda) (nth 1 def))
((and (eq (car-safe def) 'autoload) (not (eq (nth 4 def) 'keymap)))
"[Arg list not available until function definition is loaded.]")
(t t)))
(defun help-make-usage (function arglist)
(cons (if (symbolp function) function 'anonymous)
(mapcar (lambda (arg)
(if (not (symbolp arg))
(if (and (consp arg) (symbolp (car arg)))
;; CL style default values for optional args.
(cons (intern (upcase (symbol-name (car arg))))
(cdr arg))
arg)
(let ((name (symbol-name arg)))
(if (string-match "\\`&" name) arg
(intern (upcase name))))))
arglist)))
;;;###autoload
(defun describe-function-1 (function)
(let* ((def (if (symbolp function)
(symbol-function function)
function))
file-name string
(beg (if (commandp def) "an interactive " "a ")))
(setq string
(cond ((or (stringp def)
(vectorp def))
"a keyboard macro")
((subrp def)
(if (eq 'unevalled (cdr (subr-arity def)))
(concat beg "special form")
(concat beg "built-in function")))
((byte-code-function-p def)
(concat beg "compiled Lisp function"))
((symbolp def)
(while (symbolp (symbol-function def))
(setq def (symbol-function def)))
(format "an 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) 'autoload)
(setq file-name (nth 1 def))
(format "%s autoloaded %s"
(if (commandp def) "an interactive" "an")
(if (eq (nth 4 def) 'keymap) "keymap"
(if (nth 4 def) "Lisp macro" "Lisp function"))
))
((keymapp def)
(let ((is-full nil)
(elts (cdr-safe def)))
(while elts
(if (char-table-p (car-safe elts))
(setq is-full t
elts nil))
(setq elts (cdr-safe elts)))
(if is-full
"a full keymap"
"a sparse keymap")))
(t "")))
(princ string)
(with-current-buffer standard-output
(save-excursion
(save-match-data
(if (re-search-backward "alias for `\\([^`']+\\)'" nil t)
(help-xref-button 1 'help-function def)))))
(or file-name
(setq file-name (symbol-file function)))
(when (equal file-name "loaddefs.el")
;; Find the real def site of the preloaded function.
;; This is necessary only for defaliases.
(let ((location
(condition-case nil
(find-function-search-for-symbol function nil "loaddefs.el")
(error nil))))
(when location
(with-current-buffer (car location)
(goto-char (cdr location))
(when (re-search-backward
"^;;; Generated autoloads from \\(.*\\)" nil t)
(setq file-name (match-string 1)))))))
(cond
(file-name
(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 "'")
;; Make a hyperlink to the library.
(with-current-buffer standard-output
(save-excursion
(re-search-backward "`\\([^`']+\\)'" nil t)
(help-xref-button 1 'help-function-def function file-name)))))
(princ ".")
(terpri)
(when (commandp function)
(let* ((remapped (command-remapping function))
(keys (where-is-internal
(or remapped function) overriding-local-map nil nil)))
(when remapped
(princ "It is remapped to `")
(princ (symbol-name remapped))
(princ "'"))
(when keys
(princ (if remapped " which is bound to " "It is bound to "))
;; FIXME: This list can be very long (f.ex. for self-insert-command).
(princ (mapconcat 'key-description keys ", ")))
(when (or remapped keys)
(princ ".")
(terpri))))
(let* ((arglist (help-function-arglist def))
(doc (documentation function))
(usage (help-split-fundoc doc function)))
;; If definition is a keymap, skip arglist note.
(unless (keymapp def)
(princ (cond
(usage (setq doc (cdr usage)) (car usage))
((listp arglist) (help-make-usage function arglist))
((stringp arglist) arglist)
;; Maybe the arglist is in the docstring of the alias.
((let ((fun function))
(while (and (symbolp fun)
(setq fun (symbol-function fun))
(not (setq usage (help-split-fundoc
(documentation fun)
function)))))
usage)
(car usage))
((or (stringp def)
(vectorp def))
(format "\nMacro: %s" (format-kbd-macro def)))
(t "[Missing arglist. Please make a bug report.]")))
(terpri))
(let ((obsolete (and
;; function might be a lambda construct.
(symbolp function)
(get function 'byte-obsolete-info))))
(when obsolete
(terpri)
(princ "This function is obsolete")
(if (nth 2 obsolete) (princ (format " since %s" (nth 2 obsolete))))
(princ ";") (terpri)
(princ (if (stringp (car obsolete)) (car obsolete)
(format "use `%s' instead." (car obsolete))))
(terpri)))
(terpri)
(princ (or doc "Not documented.")))))
;; Variables
;;;###autoload
(defun variable-at-point ()
"Return the bound variable symbol found around point.
Return 0 if there is no such symbol."
(condition-case ()
(with-syntax-table emacs-lisp-mode-syntax-table
(save-excursion
(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))))
(or (and (symbolp obj) (boundp obj) obj)
0))))
(error 0)))
;;;###autoload
(defun describe-variable (variable &optional buffer)
"Display the full documentation of VARIABLE (a symbol).
Returns the documentation as a string, also.
If VARIABLE has a buffer-local value in BUFFER (default to the current buffer),
it is displayed along with the global value."
(interactive
(let ((v (variable-at-point))
(enable-recursive-minibuffers t)
val)
(setq val (completing-read (if (symbolp v)
(format
"Describe variable (default %s): " v)
"Describe variable: ")
obarray 'boundp t nil nil
(if (symbolp v) (symbol-name v))))
(list (if (equal val "")
v (intern val)))))
(unless (buffer-live-p buffer) (setq buffer (current-buffer)))
(if (not (symbolp variable))
(message "You did not specify a variable")
(save-excursion
(let* ((valvoid (not (with-current-buffer buffer (boundp variable))))
;; Extract the value before setting up the output buffer,
;; in case `buffer' *is* the output buffer.
(val (unless valvoid (buffer-local-value variable buffer))))
(help-setup-xref (list #'describe-variable variable buffer)
(interactive-p))
(with-output-to-temp-buffer (help-buffer)
(with-current-buffer buffer
(prin1 variable)
(if valvoid
(princ " is void")
(with-current-buffer standard-output
(princ "'s value is ")
(terpri)
(let ((from (point)))
(pp val)
(help-xref-on-pp from (point))
(if (< (point) (+ from 20))
(delete-region (1- from) from)))))
(terpri)
(when (local-variable-p variable)
(princ (format "Local in buffer %s; " (buffer-name)))
(if (not (default-boundp variable))
(princ "globally void")
(let ((val (default-value variable)))
(with-current-buffer standard-output
(princ "global value is ")
(terpri)
;; Fixme: pp can take an age if you happen to
;; ask for a very large expression. We should
;; probably print it raw once and check it's a
;; sensible size before prettyprinting. -- fx
(let ((from (point)))
(pp val)
(help-xref-on-pp from (point))
(if (< (point) (+ from 20))
(delete-region (1- from) from))))))
(terpri))
(terpri)
(with-current-buffer standard-output
(when (> (count-lines (point-min) (point-max)) 10)
;; Note that setting the syntax table like below
;; makes forward-sexp move over a `'s' at the end
;; of a symbol.
(set-syntax-table emacs-lisp-mode-syntax-table)
(goto-char (point-min))
(if valvoid
(forward-line 1)
(forward-sexp 1)
(delete-region (point) (progn (end-of-line) (point)))
(insert " value is shown below.\n\n")
(save-excursion
(insert "\n\nValue:"))))
;; Add a note for variables that have been make-var-buffer-local.
(when (and (local-variable-if-set-p variable)
(or (not (local-variable-p variable))
(with-temp-buffer
(local-variable-if-set-p variable))))
(save-excursion
(forward-line -1)
(insert "Automatically becomes buffer-local when set in any fashion.\n"))))
;; Mention if it's an alias
(let* ((alias (condition-case nil
(indirect-variable variable)
(error variable)))
(obsolete (get variable 'byte-obsolete-variable))
(doc (or (documentation-property variable 'variable-documentation)
(documentation-property alias 'variable-documentation))))
(unless (eq alias variable)
(princ (format "This variable is an alias for `%s'." alias))
(terpri)
(terpri))
(when obsolete
(princ "This variable is obsolete")
(if (cdr obsolete) (princ (format " since %s" (cdr obsolete))))
(princ ";") (terpri)
(princ (if (stringp (car obsolete)) (car obsolete)
(format "use `%s' instead." (car obsolete))))
(terpri)
(terpri))
(princ (or doc "Not documented as a variable.")))
;; Make a link to customize if this variable can be customized.
(if (custom-variable-p variable)
(let ((customize-label "customize"))
(terpri)
(terpri)
(princ (concat "You can " customize-label " this variable."))
(with-current-buffer standard-output
(save-excursion
(re-search-backward
(concat "\\(" customize-label "\\)") nil t)
(help-xref-button 1 'help-customize-variable variable)))))
;; Make a hyperlink to the library if appropriate. (Don't
;; change the format of the buffer's initial line in case
;; anything expects the current format.)
(let ((file-name (symbol-file (cons 'defvar variable))))
(when (equal file-name "loaddefs.el")
;; Find the real def site of the preloaded variable.
(let ((location
(condition-case nil
(find-variable-noselect variable file-name)
(error nil))))
(when location
(with-current-buffer (car location)
(goto-char (cdr location))
(when (re-search-backward
"^;;; Generated autoloads from \\(.*\\)" nil t)
(setq file-name (match-string 1)))))))
(when file-name
(princ "\n\nDefined in `")
(princ file-name)
(princ "'.")
(with-current-buffer standard-output
(save-excursion
(re-search-backward "`\\([^`']+\\)'" nil t)
(help-xref-button 1 'help-variable-def
variable file-name)))))
(print-help-return-message)
(save-excursion
(set-buffer standard-output)
;; Return the text we displayed.
(buffer-string))))))))
;;;###autoload
(defun describe-syntax (&optional buffer)
"Describe the syntax specifications in the syntax table of BUFFER.
The descriptions are inserted in a help buffer, which is then displayed.
BUFFER defaults to the current buffer."
(interactive)
(setq buffer (or buffer (current-buffer)))
(help-setup-xref (list #'describe-syntax buffer) (interactive-p))
(with-output-to-temp-buffer (help-buffer)
(let ((table (with-current-buffer buffer (syntax-table))))
(with-current-buffer standard-output
(describe-vector table 'internal-describe-syntax-value)
(while (setq table (char-table-parent table))
(insert "\nThe parent syntax table is:")
(describe-vector table 'internal-describe-syntax-value))))))
(defun help-describe-category-set (value)
(insert (cond
((null value) "default")
((char-table-p value) "deeper char-table ...")
(t (condition-case err
(category-set-mnemonics value)
(error "invalid"))))))
;;;###autoload
(defun describe-categories (&optional buffer)
"Describe the category specifications in the current category table.
The descriptions are inserted in a buffer, which is then displayed."
(interactive)
(setq buffer (or buffer (current-buffer)))
(help-setup-xref (list #'describe-categories buffer) (interactive-p))
(with-output-to-temp-buffer (help-buffer)
(let ((table (with-current-buffer buffer (category-table))))
(with-current-buffer standard-output
(describe-vector table 'help-describe-category-set)
(let ((docs (char-table-extra-slot table 0)))
(if (or (not (vectorp docs)) (/= (length docs) 95))
(insert "Invalid first extra slot in this char table\n")
(insert "Meanings of mnemonic characters are:\n")
(dotimes (i 95)
(let ((elt (aref docs i)))
(when elt
(insert (+ i ?\ ) ": " elt "\n"))))
(while (setq table (char-table-parent table))
(insert "\nThe parent category table is:")
(describe-vector table 'help-describe-category-set))))))))
(provide 'help-fns)
;;; help-fns.el ends here
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