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emacs/lisp/help-fns.el
Miles Bader 59ce725a3b Merge from emacs--rel--22 
Revision: emacs@sv.gnu.org/emacs--devo--0--patch-987
2008-01-08 20:46:54 +00:00

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;;; help-fns.el --- Complex help functions
;; Copyright (C) 1985, 1986, 1993, 1994, 1998, 1999, 2000, 2001,
;; 2002, 2003, 2004, 2005, 2006, 2007, 2008 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 3, 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., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, 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)
;; 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
(and fn (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-help-window (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)
(with-current-buffer standard-output
;; Return the text we displayed.
(buffer-string))))))
(defun help-split-fundoc (docstring def)
"Split a function DOCSTRING 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 DOCSTRING."
;; 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 docstring (string-match "\n\n(fn\\(\\( .*\\)?)\\)\\'" docstring))
(cons (format "(%s%s"
;; Replace `fn' with the actual function name.
(if (consp def) "anonymous" def)
(match-string 1 docstring))
(substring docstring 0 (match-beginning 0)))))
(defun help-add-fundoc-usage (docstring arglist)
"Add the usage info to DOCSTRING.
If DOCSTRING already has a usage info, then just return it unchanged.
The usage info is built from ARGLIST. DOCSTRING can be nil.
ARGLIST can also be t or a string of the form \"(FUN ARG1 ARG2 ...)\"."
(unless (stringp docstring) (setq docstring "Not documented"))
(if (or (string-match "\n\n(fn\\(\\( .*\\)?)\\)\\'" docstring) (eq arglist t))
docstring
(concat docstring
(if (string-match "\n?\n\\'" docstring)
(if (< (- (match-end 0) (match-beginning 0)) 2) "\n" "")
"\n\n")
(if (and (stringp arglist)
(string-match "\\`([^ ]+\\(.*\\))\\'" arglist))
(concat "(fn" (match-string 1 arglist) ")")
(format "%S" (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)))
;; Could be this, if we make symbol-file do the work below.
;; (defun help-C-file-name (subr-or-var kind)
;; "Return the name of the C file where SUBR-OR-VAR is defined.
;; KIND should be `var' for a variable or `subr' for a subroutine."
;; (symbol-file (if (symbolp subr-or-var) subr-or-var
;; (subr-name subr-or-var))
;; (if (eq kind 'var) 'defvar 'defun)))
;;;###autoload
(defun help-C-file-name (subr-or-var kind)
"Return the name of the C file where SUBR-OR-VAR is defined.
KIND should be `var' for a variable or `subr' for a subroutine."
(let ((docbuf (get-buffer-create " *DOC*"))
(name (if (eq 'var kind)
(concat "V" (symbol-name subr-or-var))
(concat "F" (subr-name subr-or-var)))))
(with-current-buffer docbuf
(goto-char (point-min))
(if (eobp)
(insert-file-contents-literally
(expand-file-name internal-doc-file-name doc-directory)))
(let ((file (catch 'loop
(while t
(let ((pnt (search-forward (concat "" name "\n"))))
(re-search-backward "S\\(.*\\)")
(let ((file (match-string 1)))
(if (member file build-files)
(throw 'loop file)
(goto-char pnt))))))))
(if (string-match "\\.\\(o\\|obj\\)\\'" file)
(setq file (replace-match ".c" t t file)))
(if (string-match "\\.c\\'" file)
(concat "src/" file)
file)))))
(defface help-argument-name '((((supports :slant italic)) :inherit italic))
"Face to highlight argument names in *Help* buffers."
:group 'help)
(defun help-default-arg-highlight (arg)
"Default function to highlight arguments in *Help* buffers.
It returns ARG in face `help-argument-name'; ARG is also
downcased if it displays differently than the default
face (according to `face-differs-from-default-p')."
(propertize (if (face-differs-from-default-p 'help-argument-name)
(downcase arg)
arg)
'face 'help-argument-name))
(defun help-do-arg-highlight (doc args)
(with-syntax-table (make-syntax-table emacs-lisp-mode-syntax-table)
(modify-syntax-entry ?\- "w")
(dolist (arg args doc)
(setq doc (replace-regexp-in-string
;; This is heuristic, but covers all common cases
;; except ARG1-ARG2
(concat "\\<" ; beginning of word
"\\(?:[a-z-]*-\\)?" ; for xxx-ARG
"\\("
(regexp-quote arg)
"\\)"
"\\(?:es\\|s\\|th\\)?" ; for ARGth, ARGs
"\\(?:-[a-z0-9-]+\\)?" ; for ARG-xxx, ARG-n
"\\(?:-[{([<`\"].*?\\)?"; for ARG-{x}, (x), <x>, [x], `x'
"\\>") ; end of word
(help-default-arg-highlight arg)
doc t t 1)))))
(defun help-highlight-arguments (usage doc &rest args)
(when usage
(with-temp-buffer
(insert usage)
(goto-char (point-min))
(let ((case-fold-search nil)
(next (not (or args (looking-at "\\["))))
(opt nil))
;; Make a list of all arguments
(skip-chars-forward "^ ")
(while next
(or opt (not (looking-at " &")) (setq opt t))
(if (not (re-search-forward " \\([\\[(]*\\)\\([^] &)\.]+\\)" nil t))
(setq next nil)
(setq args (cons (match-string 2) args))
(when (and opt (string= (match-string 1) "("))
;; A pesky CL-style optional argument with default value,
;; so let's skip over it
(search-backward "(")
(goto-char (scan-sexps (point) 1)))))
;; Highlight aguments in the USAGE string
(setq usage (help-do-arg-highlight (buffer-string) args))
;; Highlight arguments in the DOC string
(setq doc (and doc (help-do-arg-highlight doc args))))))
;; Return value is like the one from help-split-fundoc, but highlighted
(cons usage doc))
;;;###autoload
(defun describe-simplify-lib-file-name (file)
"Simplify a library name FILE to a relative name, and make it a source file."
(if file
;; Try converting the absolute file name to a library name.
(let ((libname (file-name-nondirectory file)))
;; Now convert that back to a file name and see if we get
;; the original one. If so, they are equivalent.
(if (equal file (locate-file libname load-path '("")))
(if (string-match "[.]elc\\'" libname)
(substring libname 0 -1)
libname)
file))))
(defun find-source-lisp-file (file-name)
(let* ((elc-file (locate-file (concat file-name
(if (string-match "\\.el" file-name)
"c"
".elc"))
load-path))
(str (if (and elc-file (file-readable-p elc-file))
(with-temp-buffer
(insert-file-contents-literally elc-file nil 0 256)
(buffer-string))))
(src-file (and str
(string-match ";;; from file \\(.*\\.el\\)" str)
(match-string 1 str))))
(if (and src-file (file-readable-p src-file))
src-file
file-name)))
(declare-function ad-get-advice-info "advice" (function))
;;;###autoload
(defun describe-function-1 (function)
(let* ((advised (and (symbolp function) (featurep 'advice)
(ad-get-advice-info function)))
;; If the function is advised, use the symbol that has the
;; real definition, if that symbol is already set up.
(real-function
(or (and advised
(cdr (assq 'origname advised))
(fboundp (cdr (assq 'origname advised)))
(cdr (assq 'origname advised)))
function))
;; Get the real definition.
(def (if (symbolp real-function)
(symbol-function real-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 'defun)))
(setq file-name (describe-simplify-lib-file-name file-name))
(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)))))))
(when (and (null file-name) (subrp def))
;; Find the C source file name.
(setq file-name (if (get-buffer " *DOC*")
(help-C-file-name def 'subr)
'C-source)))
(when 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 (if (eq file-name 'C-source) "C source code" file-name))
(princ "'")
;; See if lisp files are present where they where installed from.
(if (not (eq file-name 'C-source))
(setq file-name (find-source-lisp-file file-name)))
;; 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 real-function file-name))))
(princ ".")
(terpri)
(when (commandp function)
(if (and (eq function 'self-insert-command)
(eq (key-binding "a") 'self-insert-command)
(eq (key-binding "b") 'self-insert-command)
(eq (key-binding "c") 'self-insert-command))
(princ "It is bound to many ordinary text characters.\n")
(let* ((remapped (command-remapping function))
(keys (where-is-internal
(or remapped function) overriding-local-map nil nil))
non-modified-keys)
;; Which non-control non-meta keys run this command?
(dolist (key keys)
(if (member (event-modifiers (aref key 0)) '(nil (shift)))
(push key non-modified-keys)))
(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 "))
;; If lots of ordinary text characters run this command,
;; don't mention them one by one.
(if (< (length non-modified-keys) 10)
(princ (mapconcat 'key-description keys ", "))
(dolist (key non-modified-keys)
(setq keys (delq key keys)))
(if keys
(progn
(princ (mapconcat 'key-description keys ", "))
(princ ", and many ordinary text characters"))
(princ "many ordinary text characters"))))
(when (or remapped keys non-modified-keys)
(princ ".")
(terpri)))))
(let* ((arglist (help-function-arglist def))
(doc (documentation function))
(usage (help-split-fundoc doc function)))
(with-current-buffer standard-output
;; If definition is a keymap, skip arglist note.
(unless (keymapp def)
(let* ((use (cond
(usage (setq doc (cdr usage)) (car usage))
((listp arglist)
(format "%S" (help-make-usage function arglist)))
((stringp arglist) arglist)
;; Maybe the arglist is in the docstring of a symbol
;; this one is aliased to.
((let ((fun real-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.]")))
(high (help-highlight-arguments use doc)))
(let ((fill-begin (point)))
(insert (car high) "\n")
(fill-region fill-begin (point)))
(setq doc (cdr high))))
(let ((obsolete (and
;; function might be a lambda construct.
(symbolp function)
(get function 'byte-obsolete-info))))
(when obsolete
(princ "\nThis function is obsolete")
(when (nth 2 obsolete)
(insert (format " since %s" (nth 2 obsolete))))
(insert ";\n"
(if (stringp (car obsolete)) (car obsolete)
(format "use `%s' instead." (car obsolete)))
"\n"))
(insert "\n"
(or doc "Not documented.")))))))
;; Variables
;;;###autoload
(defun variable-at-point (&optional any-symbol)
"Return the bound variable symbol found at or before point.
Return 0 if there is no such symbol.
If ANY-SYMBOL is non-nil, don't insist the symbol be bound."
(or (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))))
(and (symbolp obj) (boundp obj) obj))))
(error nil))
(let* ((str (find-tag-default))
(sym (if str (intern-soft str))))
(if (and sym (or any-symbol (boundp sym)))
sym
(save-match-data
(when (and str (string-match "\\`\\W*\\(.*?\\)\\W*\\'" str))
(setq sym (intern-soft (match-string 1 str)))
(and (or any-symbol (boundp sym)) sym)))))
0))
(defun describe-variable-custom-version-info (variable)
(let ((custom-version (get variable 'custom-version))
(cpv (get variable 'custom-package-version))
(output nil))
(if custom-version
(setq output
(format "This variable was introduced, or its default value was changed, in\nversion %s of Emacs.\n"
custom-version))
(when cpv
(let* ((package (car-safe cpv))
(version (car (cdr-safe cpv)))
(pkg-versions (assq package customize-package-emacs-version-alist))
(emacsv (cdr (assoc version pkg-versions))))
(if (and package version)
(setq output
(format (concat "This variable was introduced, or its default value was changed, in\nversion %s of the %s package"
(if emacsv
(format " that is part of Emacs %s" emacsv))
".\n")
version package))))))
output))
;;;###autoload
(defun describe-variable (variable &optional buffer frame)
"Display the full documentation of VARIABLE (a symbol).
Returns the documentation as a string, also.
If VARIABLE has a buffer-local value in BUFFER or FRAME
\(default to the current buffer and current frame),
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
'(lambda (vv)
(or (boundp vv)
(get vv 'variable-documentation)))
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)))
(unless (frame-live-p frame) (setq frame (selected-frame)))
(if (not (symbolp variable))
(message "You did not specify a variable")
(save-excursion
(let ((valvoid (not (with-current-buffer buffer (boundp variable))))
val val-start-pos locus)
;; Extract the value before setting up the output buffer,
;; in case `buffer' *is* the output buffer.
(unless valvoid
(with-selected-frame frame
(with-current-buffer buffer
(setq val (symbol-value variable)
locus (variable-binding-locus variable)))))
(help-setup-xref (list #'describe-variable variable buffer)
(interactive-p))
(with-help-window (help-buffer)
(with-current-buffer buffer
(prin1 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 variable 'defvar)))
(setq file-name (describe-simplify-lib-file-name file-name))
(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)
(when (cdr location)
(goto-char (cdr location)))
(when (re-search-backward
"^;;; Generated autoloads from \\(.*\\)" nil t)
(setq file-name (match-string 1)))))))
(when (and (null file-name)
(integerp (get variable 'variable-documentation)))
;; It's a variable not defined in Elisp but in C.
(setq file-name
(if (get-buffer " *DOC*")
(help-C-file-name variable 'var)
'C-source)))
(if file-name
(progn
(princ " is a variable defined in `")
(princ (if (eq file-name 'C-source) "C source code" file-name))
(princ "'.\n")
(with-current-buffer standard-output
(save-excursion
(re-search-backward "`\\([^`']+\\)'" nil t)
(help-xref-button 1 'help-variable-def
variable file-name)))
(if valvoid
(princ "It is void as a variable.")
(princ "Its ")))
(if valvoid
(princ " is void as a variable.")
(princ "'s "))))
(if valvoid
nil
(with-current-buffer standard-output
(setq val-start-pos (point))
(princ "value is ")
(terpri)
(let ((from (point)))
(pp val)
;; Hyperlinks in variable's value are quite frequently
;; inappropriate e.g C-h v <RET> features <RET>
;; (help-xref-on-pp from (point))
(if (< (point) (+ from 20))
(delete-region (1- from) from)))))
(terpri)
(when locus
(if (bufferp locus)
(princ (format "%socal in buffer %s; "
(if (get variable 'permanent-local)
"Permanently l" "L")
(buffer-name)))
(princ (format "It is a frame-local variable; ")))
(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)
;; See previous comment for this function.
;; (help-xref-on-pp from (point))
(if (< (point) (+ from 20))
(delete-region (1- from) from))))))
(terpri))
;; If the value is large, move it to the end.
(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 val-start-pos)
;; The line below previously read as
;; (delete-region (point) (progn (end-of-line) (point)))
;; which suppressed display of the buffer local value for
;; large values.
(when (looking-at "value is") (replace-match ""))
(save-excursion
(insert "\n\nValue:")
(set (make-local-variable 'help-button-cache)
(point-marker)))
(insert "value is shown ")
(insert-button "below"
'action help-button-cache
'follow-link t
'help-echo "mouse-2, RET: show value")
(insert ".\n")))
(terpri)
(let* ((alias (condition-case nil
(indirect-variable variable)
(error variable)))
(obsolete (get variable 'byte-obsolete-variable))
(safe-var (get variable 'safe-local-variable))
(doc (or (documentation-property variable 'variable-documentation)
(documentation-property alias 'variable-documentation)))
(extra-line nil))
;; 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))))
(setq extra-line t)
(princ " Automatically becomes buffer-local when set in any fashion.\n"))
;; Mention if it's an alias
(unless (eq alias variable)
(setq extra-line t)
(princ (format " This variable is an alias for `%s'.\n" alias)))
(when obsolete
(setq extra-line t)
(princ " This variable is obsolete")
(if (cdr obsolete) (princ (format " since %s" (cdr obsolete))))
(princ ";\n ")
(princ (if (stringp (car obsolete)) (car obsolete)
(format "use `%s' instead." (car obsolete))))
(terpri))
(when safe-var
(setq extra-line t)
(princ " This variable is safe as a file local variable ")
(princ "if its value\n satisfies the predicate ")
(princ (if (byte-code-function-p safe-var)
"which is byte-compiled expression.\n"
(format "`%s'.\n" safe-var))))
(if extra-line (terpri))
(princ "Documentation:\n")
(with-current-buffer standard-output
(insert (or doc "Not documented as a variable."))))
;; Make a link to customize if this variable can be customized.
(when (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))))
;; Note variable's version or package version
(let ((output (describe-variable-custom-version-info variable)))
(when output
(terpri)
(terpri)
(princ output))))
(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-help-window (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.
If BUFFER is non-nil, then describe BUFFER's category table instead.
BUFFER should be a buffer or a buffer name."
(interactive)
(setq buffer (or buffer (current-buffer)))
(help-setup-xref (list #'describe-categories buffer) (interactive-p))
(with-help-window (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 ?\s) ": " 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)
;; arch-tag: 9e10331c-ae81-4d13-965d-c4819aaab0b3
;;; help-fns.el ends here
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