code.delx.au - gnu-emacs/blob - lisp/help-fns.el

   1 ;;; help-fns.el --- Complex help functions -*- lexical-binding: t -*-
   2
   3 ;; Copyright (C) 1985-1986, 1993-1994, 1998-2016 Free Software
   4 ;; Foundation, Inc.
   5
   6 ;; Maintainer: emacs-devel@gnu.org
   7 ;; Keywords: help, internal
   8 ;; Package: emacs
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; GNU Emacs is free software: you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation, either version 3 of the License, or
  15 ;; (at your option) any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  24
  25 ;;; Commentary:
  26
  27 ;; This file contains those help commands which are complicated, and
  28 ;; which may not be used in every session.  For example
  29 ;; `describe-function' will probably be heavily used when doing elisp
  30 ;; programming, but not if just editing C files.  Simpler help commands
  31 ;; are in help.el
  32
  33 ;;; Code:
  34
  35 (require 'cl-lib)
  36 (require 'help-mode)
  37 (require 'radix-tree)
  38
  39 (defvar help-fns-describe-function-functions nil
  40   "List of functions to run in help buffer in `describe-function'.
  41 Those functions will be run after the header line and argument
  42 list was inserted, and before the documentation will be inserted.
  43 The functions will receive the function name as argument.")
  44
  45 ;; Functions
  46
  47 (defvar help-definition-prefixes nil
  48   ;; FIXME: We keep `definition-prefixes' as a hash-table so as to
  49   ;; avoid pre-loading radix-tree and because it takes slightly less
  50   ;; memory.  But when we use this table it's more efficient to
  51   ;; represent it as a radix tree, since the main operation is to do
  52   ;; `radix-tree-prefixes'.  Maybe we should just bite the bullet and
  53   ;; use a radix tree for `definition-prefixes' (it's not *that*
  54   ;; costly, really).
  55   "Radix-tree representation replacing `definition-prefixes'.")
  56
  57 (defun help-definition-prefixes ()
  58   "Return the up-to-date radix-tree form of `definition-prefixes'."
  59   (when (> (hash-table-count definition-prefixes) 0)
  60     (maphash (lambda (prefix files)
  61                (let ((old (radix-tree-lookup help-definition-prefixes prefix)))
  62                  (setq help-definition-prefixes
  63                        (radix-tree-insert help-definition-prefixes
  64                                           prefix (append old files)))))
  65              definition-prefixes)
  66     (clrhash definition-prefixes))
  67   help-definition-prefixes)
  68
  69 (defun help--loaded-p (file)
  70   "Try and figure out if FILE has already been loaded."
  71   (or (let ((feature (intern-soft file)))
  72         (and feature (featurep feature)))
  73       (let* ((re (load-history-regexp file))
  74              (done nil))
  75         (dolist (x load-history)
  76           (if (string-match-p re (car x)) (setq done t)))
  77         done)))
  78
  79 (defun help--load-prefixes (prefixes)
  80   (pcase-dolist (`(,prefix . ,files) prefixes)
  81     (setq help-definition-prefixes
  82           (radix-tree-insert help-definition-prefixes prefix nil))
  83     (dolist (file files)
  84       ;; FIXME: Should we scan help-definition-prefixes to remove
  85       ;; other prefixes of the same file?
  86       ;; FIXME: this regexp business is not good enough: for file
  87       ;; `toto', it will say `toto' is loaded when in reality it was
  88       ;; just cedet/semantic/toto that has been loaded.
  89       (unless (help--loaded-p file)
  90         (load file 'noerror 'nomessage)))))
  91
  92 (defun help--symbol-completion-table (string pred action)
  93   (let ((prefixes (radix-tree-prefixes (help-definition-prefixes) string)))
  94     (help--load-prefixes prefixes))
  95   (let ((prefix-completions
  96          (mapcar #'intern (all-completions string definition-prefixes))))
  97     (complete-with-action action obarray string
  98                           (if pred (lambda (sym)
  99                                      (or (funcall pred sym)
 100                                          (memq sym prefix-completions)))))))
 101
 102 (defvar describe-function-orig-buffer nil
 103   "Buffer that was current when `describe-function' was invoked.
 104 Functions on `help-fns-describe-function-functions' can use this
 105 to get buffer-local values.")
 106
 107 ;;;###autoload
 108 (defun describe-function (function)
 109   "Display the full documentation of FUNCTION (a symbol)."
 110   (interactive
 111    (let ((fn (function-called-at-point))
 112          (enable-recursive-minibuffers t)
 113          val)
 114      (setq val (completing-read (if fn
 115                                     (format "Describe function (default %s): " fn)
 116                                   "Describe function: ")
 117                                 #'help--symbol-completion-table
 118                                 #'fboundp
 119                                 t nil nil (and fn (symbol-name fn))))
 120      (list (if (equal val "")
 121                fn (intern val)))))
 122   (or (and function (symbolp function))
 123       (user-error "You didn't specify a function symbol"))
 124   (or (fboundp function)
 125       (user-error "Symbol's function definition is void: %s" function))
 126
 127   ;; We save describe-function-orig-buffer on the help xref stack, so
 128   ;; it is restored by the back/forward buttons.  'help-buffer'
 129   ;; expects (current-buffer) to be a help buffer when processing
 130   ;; those buttons, so we can't change the current buffer before
 131   ;; calling that.
 132   (let ((describe-function-orig-buffer
 133          (or describe-function-orig-buffer
 134              (current-buffer))))
 135
 136     (help-setup-xref
 137      (list (lambda (function buffer)
 138              (let ((describe-function-orig-buffer
 139                     (if (buffer-live-p buffer) buffer)))
 140                (describe-function function)))
 141            function describe-function-orig-buffer)
 142      (called-interactively-p 'interactive))
 143
 144     (save-excursion
 145       (with-help-window (help-buffer)
 146         (prin1 function)
 147         ;; Use " is " instead of a colon so that
 148         ;; it is easier to get out the function name using forward-sexp.
 149         (princ " is ")
 150         (describe-function-1 function)
 151         (with-current-buffer standard-output
 152           ;; Return the text we displayed.
 153           (buffer-string))))
 154     ))
 155
 156
 157 ;; Could be this, if we make symbol-file do the work below.
 158 ;; (defun help-C-file-name (subr-or-var kind)
 159 ;;   "Return the name of the C file where SUBR-OR-VAR is defined.
 160 ;; KIND should be `var' for a variable or `subr' for a subroutine."
 161 ;;   (symbol-file (if (symbolp subr-or-var) subr-or-var
 162 ;;               (subr-name subr-or-var))
 163 ;;             (if (eq kind 'var) 'defvar 'defun)))
 164 ;;;###autoload
 165 (defun help-C-file-name (subr-or-var kind)
 166   "Return the name of the C file where SUBR-OR-VAR is defined.
 167 KIND should be `var' for a variable or `subr' for a subroutine."
 168   (let ((docbuf (get-buffer-create " *DOC*"))
 169         (name (if (eq 'var kind)
 170                   (concat "V" (symbol-name subr-or-var))
 171                 (concat "F" (subr-name (advice--cd*r subr-or-var))))))
 172     (with-current-buffer docbuf
 173       (goto-char (point-min))
 174       (if (eobp)
 175           (insert-file-contents-literally
 176            (expand-file-name internal-doc-file-name doc-directory)))
 177       (let ((file (catch 'loop
 178                     (while t
 179                       (let ((pnt (search-forward (concat "\1f" name "\n"))))
 180                         (re-search-backward "\1fS\\(.*\\)")
 181                         (let ((file (match-string 1)))
 182                           (if (member file build-files)
 183                               (throw 'loop file)
 184                             (goto-char pnt))))))))
 185         (if (string-match "^ns.*\\(\\.o\\|obj\\)\\'" file)
 186             (setq file (replace-match ".m" t t file 1))
 187           (if (string-match "\\.\\(o\\|obj\\)\\'" file)
 188               (setq file (replace-match ".c" t t file))))
 189         (if (string-match "\\.\\(c\\|m\\)\\'" file)
 190             (concat "src/" file)
 191           file)))))
 192
 193 (defcustom help-downcase-arguments nil
 194   "If non-nil, argument names in *Help* buffers are downcased."
 195   :type 'boolean
 196   :group 'help
 197   :version "23.2")
 198
 199 (defun help-highlight-arg (arg)
 200   "Highlight ARG as an argument name for a *Help* buffer.
 201 Return ARG in face `help-argument-name'; ARG is also downcased
 202 if the variable `help-downcase-arguments' is non-nil."
 203   (propertize (if help-downcase-arguments (downcase arg) arg)
 204               'face 'help-argument-name))
 205
 206 (defun help-do-arg-highlight (doc args)
 207   (with-syntax-table (make-syntax-table emacs-lisp-mode-syntax-table)
 208     (modify-syntax-entry ?\- "w")
 209     (dolist (arg args)
 210       (setq doc (replace-regexp-in-string
 211                  ;; This is heuristic, but covers all common cases
 212                  ;; except ARG1-ARG2
 213                  (concat "\\<"                   ; beginning of word
 214                          "\\(?:[a-z-]*-\\)?"     ; for xxx-ARG
 215                          "\\("
 216                          (regexp-quote arg)
 217                          "\\)"
 218                          "\\(?:es\\|s\\|th\\)?"  ; for ARGth, ARGs
 219                          "\\(?:-[a-z0-9-]+\\)?"  ; for ARG-xxx, ARG-n
 220                          "\\(?:-[{([<`\"‘].*?\\)?"; for ARG-{x}, (x), <x>, [x], `x', ‘x’
 221                          "\\>")                  ; end of word
 222                  (help-highlight-arg arg)
 223                  doc t t 1)))
 224     doc))
 225
 226 (defun help-highlight-arguments (usage doc &rest args)
 227   (when (and usage (string-match "^(" usage))
 228     (with-temp-buffer
 229       (insert usage)
 230       (goto-char (point-min))
 231       (let ((case-fold-search nil)
 232             (next (not (or args (looking-at "\\["))))
 233             (opt nil))
 234         ;; Make a list of all arguments
 235         (skip-chars-forward "^ ")
 236         (while next
 237           (or opt (not (looking-at " &")) (setq opt t))
 238           (if (not (re-search-forward " \\([\\[(]*\\)\\([^] &).]+\\)" nil t))
 239               (setq next nil)
 240             (setq args (cons (match-string 2) args))
 241             (when (and opt (string= (match-string 1) "("))
 242               ;; A pesky CL-style optional argument with default value,
 243               ;; so let's skip over it
 244               (search-backward "(")
 245               (goto-char (scan-sexps (point) 1)))))
 246         ;; Highlight arguments in the USAGE string
 247         (setq usage (help-do-arg-highlight (buffer-string) args))
 248         ;; Highlight arguments in the DOC string
 249         (setq doc (and doc (help-do-arg-highlight doc args))))))
 250   ;; Return value is like the one from help-split-fundoc, but highlighted
 251   (cons usage doc))
 252
 253 ;; The following function was compiled from the former functions
 254 ;; `describe-simplify-lib-file-name' and `find-source-lisp-file' with
 255 ;; some excerpts from `describe-function-1' and `describe-variable'.
 256 ;; The only additional twists provided are (1) locate the defining file
 257 ;; for autoloaded functions, and (2) give preference to files in the
 258 ;; "install directory" (directories found via `load-path') rather than
 259 ;; to files in the "compile directory" (directories found by searching
 260 ;; the loaddefs.el file).  We autoload it because it's also used by
 261 ;; `describe-face' (instead of `describe-simplify-lib-file-name').
 262
 263 ;;;###autoload
 264 (defun find-lisp-object-file-name (object type)
 265   "Guess the file that defined the Lisp object OBJECT, of type TYPE.
 266 OBJECT should be a symbol associated with a function, variable, or face;
 267   alternatively, it can be a function definition.
 268 If TYPE is `defvar', search for a variable definition.
 269 If TYPE is `defface', search for a face definition.
 270 If TYPE is not a symbol, search for a function definition.
 271
 272 The return value is the absolute name of a readable file where OBJECT is
 273 defined.  If several such files exist, preference is given to a file
 274 found via `load-path'.  The return value can also be `C-source', which
 275 means that OBJECT is a function or variable defined in C.  If no
 276 suitable file is found, return nil."
 277   (let* ((autoloaded (autoloadp type))
 278          (file-name (or (and autoloaded (nth 1 type))
 279                         (symbol-file
 280                          ;; FIXME: Why do we have this weird "If TYPE is the
 281                          ;; value returned by `symbol-function' for a function
 282                          ;; symbol" exception?
 283                          object (or (if (symbolp type) type) 'defun)))))
 284     (cond
 285      (autoloaded
 286       ;; An autoloaded function: Locate the file since `symbol-function'
 287       ;; has only returned a bare string here.
 288       (setq file-name
 289             (locate-file file-name load-path '(".el" ".elc") 'readable)))
 290      ((and (stringp file-name)
 291            (string-match "[.]*loaddefs.el\\'" file-name))
 292       ;; An autoloaded variable or face.  Visit loaddefs.el in a buffer
 293       ;; and try to extract the defining file.  The following form is
 294       ;; from `describe-function-1' and `describe-variable'.
 295       (let ((location
 296              (condition-case nil
 297                  (find-function-search-for-symbol object nil file-name)
 298                (error nil))))
 299         (when (cdr location)
 300           (with-current-buffer (car location)
 301             (goto-char (cdr location))
 302             (when (re-search-backward
 303                    "^;;; Generated autoloads from \\(.*\\)" nil t)
 304               (setq file-name
 305                     (locate-file
 306                      (file-name-sans-extension
 307                       (match-string-no-properties 1))
 308                      load-path '(".el" ".elc") 'readable))))))))
 309
 310     (cond
 311      ((and (not file-name) (subrp type))
 312       ;; A built-in function.  The form is from `describe-function-1'.
 313       (if (get-buffer " *DOC*")
 314           (help-C-file-name type 'subr)
 315         'C-source))
 316      ((and (not file-name) (symbolp object)
 317            (integerp (get object 'variable-documentation)))
 318       ;; A variable defined in C.  The form is from `describe-variable'.
 319       (if (get-buffer " *DOC*")
 320           (help-C-file-name object 'var)
 321         'C-source))
 322      ((not (stringp file-name))
 323       ;; If we don't have a file-name string by now, we lost.
 324       nil)
 325      ;; Now, `file-name' should have become an absolute file name.
 326      ;; For files loaded from ~/.foo.elc, try ~/.foo.
 327      ;; This applies to config files like ~/.emacs,
 328      ;; which people sometimes compile.
 329      ((let (fn)
 330         (and (string-match "\\`\\..*\\.elc\\'"
 331                            (file-name-nondirectory file-name))
 332              (string-equal (file-name-directory file-name)
 333                            (file-name-as-directory (expand-file-name "~")))
 334              (file-readable-p (setq fn (file-name-sans-extension file-name)))
 335              fn)))
 336      ;; When the Elisp source file can be found in the install
 337      ;; directory, return the name of that file.
 338      ((let ((lib-name
 339              (if (string-match "[.]elc\\'" file-name)
 340                  (substring-no-properties file-name 0 -1)
 341                file-name)))
 342         (or (and (file-readable-p lib-name) lib-name)
 343             ;; The library might be compressed.
 344             (and (file-readable-p (concat lib-name ".gz")) lib-name))))
 345      ((let* ((lib-name (file-name-nondirectory file-name))
 346              ;; The next form is from `describe-simplify-lib-file-name'.
 347              (file-name
 348               ;; Try converting the absolute file name to a library
 349               ;; name, convert that back to a file name and see if we
 350               ;; get the original one.  If so, they are equivalent.
 351               (if (equal file-name (locate-file lib-name load-path '("")))
 352                   (if (string-match "[.]elc\\'" lib-name)
 353                       (substring-no-properties lib-name 0 -1)
 354                     lib-name)
 355                 file-name))
 356              (src-file (locate-library file-name t nil 'readable)))
 357         (and src-file (file-readable-p src-file) src-file))))))
 358
 359 (defun help-fns--key-bindings (function)
 360   (when (commandp function)
 361     (let ((pt2 (with-current-buffer standard-output (point)))
 362           (remapped (command-remapping function)))
 363       (unless (memq remapped '(ignore undefined))
 364         (let ((keys (where-is-internal
 365                      (or remapped function) overriding-local-map nil nil))
 366               non-modified-keys)
 367           (if (and (eq function 'self-insert-command)
 368                    (vectorp (car-safe keys))
 369                    (consp (aref (car keys) 0)))
 370               (princ "It is bound to many ordinary text characters.\n")
 371             ;; Which non-control non-meta keys run this command?
 372             (dolist (key keys)
 373               (if (member (event-modifiers (aref key 0)) '(nil (shift)))
 374                   (push key non-modified-keys)))
 375             (when remapped
 376               (princ "Its keys are remapped to ")
 377               (princ (if (symbolp remapped)
 378                          (format-message "`%s'" remapped)
 379                        "an anonymous command"))
 380               (princ ".\n"))
 381
 382             (when keys
 383               (princ (if remapped
 384                          "Without this remapping, it would be bound to "
 385                        "It is bound to "))
 386               ;; If lots of ordinary text characters run this command,
 387               ;; don't mention them one by one.
 388               (if (< (length non-modified-keys) 10)
 389                   (princ (mapconcat 'key-description keys ", "))
 390                 (dolist (key non-modified-keys)
 391                   (setq keys (delq key keys)))
 392                 (if keys
 393                     (progn
 394                       (princ (mapconcat 'key-description keys ", "))
 395                       (princ ", and many ordinary text characters"))
 396                   (princ "many ordinary text characters"))))
 397             (when (or remapped keys non-modified-keys)
 398               (princ ".")
 399               (terpri)))))
 400
 401       (with-current-buffer standard-output
 402         (fill-region-as-paragraph pt2 (point))
 403         (unless (looking-back "\n\n" (- (point) 2))
 404           (terpri))))))
 405
 406 (defun help-fns--compiler-macro (function)
 407   (let ((handler (function-get function 'compiler-macro)))
 408     (when handler
 409       (insert "\nThis function has a compiler macro")
 410       (if (symbolp handler)
 411           (progn
 412             (insert (format-message " `%s'" handler))
 413             (save-excursion
 414               (re-search-backward (substitute-command-keys "`\\([^`']+\\)'")
 415                                   nil t)
 416               (help-xref-button 1 'help-function handler)))
 417         ;; FIXME: Obsolete since 24.4.
 418         (let ((lib (get function 'compiler-macro-file)))
 419           (when (stringp lib)
 420             (insert (format-message " in `%s'" lib))
 421             (save-excursion
 422               (re-search-backward (substitute-command-keys "`\\([^`']+\\)'")
 423                                   nil t)
 424               (help-xref-button 1 'help-function-cmacro function lib)))))
 425       (insert ".\n"))))
 426
 427 (defun help-fns--signature (function doc real-def real-function buffer)
 428   "Insert usage at point and return docstring.  With highlighting."
 429   (if (keymapp function)
 430       doc                       ; If definition is a keymap, skip arglist note.
 431     (let* ((advertised (gethash real-def advertised-signature-table t))
 432            (arglist (if (listp advertised)
 433                         advertised (help-function-arglist real-def)))
 434            (usage (help-split-fundoc doc function)))
 435       (if usage (setq doc (cdr usage)))
 436       (let* ((use (cond
 437                    ((and usage (not (listp advertised))) (car usage))
 438                    ((listp arglist)
 439                     (help--make-usage-docstring function arglist))
 440                    ((stringp arglist) arglist)
 441                    ;; Maybe the arglist is in the docstring of a symbol
 442                    ;; this one is aliased to.
 443                    ((let ((fun real-function))
 444                       (while (and (symbolp fun)
 445                                   (setq fun (symbol-function fun))
 446                                   (not (setq usage (help-split-fundoc
 447                                                     (documentation fun)
 448                                                     function)))))
 449                       usage)
 450                     (car usage))
 451                    ((or (stringp real-def)
 452                         (vectorp real-def))
 453                     (format "\nMacro: %s"
 454                             (help--docstring-quote
 455                              (format-kbd-macro real-def))))
 456                    (t "[Missing arglist.  Please make a bug report.]")))
 457              ;; Insert "`X", not "(\` X)", when documenting `X.
 458              (use1 (replace-regexp-in-string
 459                     "\\`(\\\\=\\\\\\\\=` \\([^\n ]*\\))\\'"
 460                     "\\\\=`\\1" use t))
 461              (high (if buffer
 462                        (let (subst-use1 subst-doc)
 463                          (with-current-buffer buffer
 464                            (setq subst-use1 (substitute-command-keys use1))
 465                            (setq subst-doc (substitute-command-keys doc)))
 466                          (help-highlight-arguments subst-use1 subst-doc))
 467                      (cons use1 doc))))
 468         (let ((fill-begin (point))
 469               (high-usage (car high))
 470               (high-doc (cdr high)))
 471           (insert high-usage "\n")
 472           (fill-region fill-begin (point))
 473           high-doc)))))
 474
 475 (defun help-fns--parent-mode (function)
 476   ;; If this is a derived mode, link to the parent.
 477   (let ((parent-mode (and (symbolp function)
 478                           (get function
 479                                'derived-mode-parent))))
 480     (when parent-mode
 481       (insert (substitute-command-keys "\nParent mode: `"))
 482       (let ((beg (point)))
 483         (insert (format "%s" parent-mode))
 484         (make-text-button beg (point)
 485                           'type 'help-function
 486                           'help-args (list parent-mode)))
 487       (insert (substitute-command-keys "'.\n")))))
 488
 489 (defun help-fns--obsolete (function)
 490   ;; Ignore lambda constructs, keyboard macros, etc.
 491   (let* ((obsolete (and (symbolp function)
 492                         (get function 'byte-obsolete-info)))
 493          (use (car obsolete)))
 494     (when obsolete
 495       (insert "\nThis "
 496               (if (eq (car-safe (symbol-function function)) 'macro)
 497                   "macro"
 498                 "function")
 499               " is obsolete")
 500       (when (nth 2 obsolete)
 501         (insert (format " since %s" (nth 2 obsolete))))
 502       (insert (cond ((stringp use) (concat ";\n" use))
 503                     (use (format-message ";\nuse `%s' instead." use))
 504                     (t "."))
 505               "\n"))))
 506
 507 ;; We could use `symbol-file' but this is a wee bit more efficient.
 508 (defun help-fns--autoloaded-p (function file)
 509   "Return non-nil if FUNCTION has previously been autoloaded.
 510 FILE is the file where FUNCTION was probably defined."
 511   (let* ((file (file-name-sans-extension (file-truename file)))
 512          (load-hist load-history)
 513          (target (cons t function))
 514          found)
 515     (while (and load-hist (not found))
 516       (and (caar load-hist)
 517            (equal (file-name-sans-extension (caar load-hist)) file)
 518            (setq found (member target (cdar load-hist))))
 519       (setq load-hist (cdr load-hist)))
 520     found))
 521
 522 (defun help-fns--interactive-only (function)
 523   "Insert some help blurb if FUNCTION should only be used interactively."
 524   ;; Ignore lambda constructs, keyboard macros, etc.
 525   (and (symbolp function)
 526        (not (eq (car-safe (symbol-function function)) 'macro))
 527        (let* ((interactive-only
 528                (or (get function 'interactive-only)
 529                    (if (boundp 'byte-compile-interactive-only-functions)
 530                        (memq function
 531                              byte-compile-interactive-only-functions)))))
 532          (when interactive-only
 533            (insert "\nThis function is for interactive use only"
 534                    ;; Cf byte-compile-form.
 535                    (cond ((stringp interactive-only)
 536                           (format ";\nin Lisp code %s" interactive-only))
 537                          ((and (symbolp 'interactive-only)
 538                                (not (eq interactive-only t)))
 539                           (format-message ";\nin Lisp code use `%s' instead."
 540                                           interactive-only))
 541                          (t "."))
 542                    "\n")))))
 543
 544 (defun help-fns-short-filename (filename)
 545   (let* ((abbrev (abbreviate-file-name filename))
 546          (short abbrev))
 547     (dolist (dir load-path)
 548       (let ((rel (file-relative-name filename dir)))
 549         (if (< (length rel) (length short))
 550             (setq short rel)))
 551       (let ((rel (file-relative-name abbrev dir)))
 552         (if (< (length rel) (length short))
 553             (setq short rel))))
 554     short))
 555
 556 ;;;###autoload
 557 (defun describe-function-1 (function)
 558   (let* ((advised (and (symbolp function)
 559                        (featurep 'nadvice)
 560                        (advice--p (advice--symbol-function function))))
 561          ;; If the function is advised, use the symbol that has the
 562          ;; real definition, if that symbol is already set up.
 563          (real-function
 564           (or (and advised
 565                    (advice--cd*r (advice--symbol-function function)))
 566               function))
 567          ;; Get the real definition.
 568          (def (if (symbolp real-function)
 569                   (or (symbol-function real-function)
 570                       (signal 'void-function (list real-function)))
 571                 real-function))
 572          (aliased (or (symbolp def)
 573                       ;; Advised & aliased function.
 574                       (and advised (symbolp real-function)
 575                            (not (eq 'autoload (car-safe def))))
 576                       (and (subrp def)
 577                            (not (string= (subr-name def)
 578                                          (symbol-name function))))))
 579          (real-def (cond
 580                     ((and aliased (not (subrp def)))
 581                      (let ((f real-function))
 582                        (while (and (fboundp f)
 583                                    (symbolp (symbol-function f)))
 584                          (setq f (symbol-function f)))
 585                        f))
 586                     ((subrp def) (intern (subr-name def)))
 587                     (t def)))
 588          (sig-key (if (subrp def)
 589                       (indirect-function real-def)
 590                     real-def))
 591          (file-name (find-lisp-object-file-name function (if aliased 'defun
 592                                                            def)))
 593          (pt1 (with-current-buffer (help-buffer) (point)))
 594          (beg (if (and (or (byte-code-function-p def)
 595                            (keymapp def)
 596                            (memq (car-safe def) '(macro lambda closure)))
 597                        (stringp file-name)
 598                        (help-fns--autoloaded-p function file-name))
 599                   (if (commandp def)
 600                       "an interactive autoloaded "
 601                     "an autoloaded ")
 602                 (if (commandp def) "an interactive " "a "))))
 603
 604     ;; Print what kind of function-like object FUNCTION is.
 605     (princ (cond ((or (stringp def) (vectorp def))
 606                   "a keyboard macro")
 607                  ;; Aliases are Lisp functions, so we need to check
 608                  ;; aliases before functions.
 609                  (aliased
 610                   (format-message "an alias for `%s'" real-def))
 611                  ((subrp def)
 612                   (if (eq 'unevalled (cdr (subr-arity def)))
 613                       (concat beg "special form")
 614                     (concat beg "built-in function")))
 615                  ((autoloadp def)
 616                   (format "%s autoloaded %s"
 617                           (if (commandp def) "an interactive" "an")
 618                           (if (eq (nth 4 def) 'keymap) "keymap"
 619                             (if (nth 4 def) "Lisp macro" "Lisp function"))))
 620                  ((or (eq (car-safe def) 'macro)
 621                       ;; For advised macros, def is a lambda
 622                       ;; expression or a byte-code-function-p, so we
 623                       ;; need to check macros before functions.
 624                       (macrop function))
 625                   (concat beg "Lisp macro"))
 626                  ((byte-code-function-p def)
 627                   (concat beg "compiled Lisp function"))
 628                  ((eq (car-safe def) 'lambda)
 629                   (concat beg "Lisp function"))
 630                  ((eq (car-safe def) 'closure)
 631                   (concat beg "Lisp closure"))
 632                  ((keymapp def)
 633                   (let ((is-full nil)
 634                         (elts (cdr-safe def)))
 635                     (while elts
 636                       (if (char-table-p (car-safe elts))
 637                           (setq is-full t
 638                                 elts nil))
 639                       (setq elts (cdr-safe elts)))
 640                     (concat beg (if is-full "keymap" "sparse keymap"))))
 641                  (t "")))
 642
 643     (if (and aliased (not (fboundp real-def)))
 644         (princ ",\nwhich is not defined.  Please make a bug report.")
 645       (with-current-buffer standard-output
 646         (save-excursion
 647           (save-match-data
 648             (when (re-search-backward (substitute-command-keys
 649                                        "alias for `\\([^`']+\\)'")
 650                                       nil t)
 651               (help-xref-button 1 'help-function real-def)))))
 652
 653       (when file-name
 654         ;; We used to add .el to the file name,
 655         ;; but that's completely wrong when the user used load-file.
 656         (princ (format-message " in `%s'"
 657                                (if (eq file-name 'C-source)
 658                                    "C source code"
 659                                  (help-fns-short-filename file-name))))
 660         ;; Make a hyperlink to the library.
 661         (with-current-buffer standard-output
 662           (save-excursion
 663             (re-search-backward (substitute-command-keys "`\\([^`']+\\)'")
 664                                 nil t)
 665             (help-xref-button 1 'help-function-def function file-name))))
 666       (princ ".")
 667       (with-current-buffer (help-buffer)
 668         (fill-region-as-paragraph (save-excursion (goto-char pt1) (forward-line 0) (point))
 669                                   (point)))
 670       (terpri)(terpri)
 671
 672       (let ((doc-raw (documentation function t))
 673             (key-bindings-buffer (current-buffer)))
 674
 675         ;; If the function is autoloaded, and its docstring has
 676         ;; key substitution constructs, load the library.
 677         (and (autoloadp real-def) doc-raw
 678              help-enable-auto-load
 679              (string-match "\\([^\\]=\\|[^=]\\|\\`\\)\\\\[[{<]" doc-raw)
 680              (autoload-do-load real-def))
 681
 682         (help-fns--key-bindings function)
 683         (with-current-buffer standard-output
 684           (let ((doc (help-fns--signature function doc-raw sig-key
 685                                           real-function key-bindings-buffer)))
 686             (run-hook-with-args 'help-fns-describe-function-functions function)
 687             (insert "\n"
 688                     (or doc "Not documented."))
 689             ;; Avoid asking the user annoying questions if she decides
 690             ;; to save the help buffer, when her locale's codeset
 691             ;; isn't UTF-8.
 692             (unless (memq text-quoting-style '(straight grave))
 693               (set-buffer-file-coding-system 'utf-8))))))))
 694
 695 ;; Add defaults to `help-fns-describe-function-functions'.
 696 (add-hook 'help-fns-describe-function-functions #'help-fns--obsolete)
 697 (add-hook 'help-fns-describe-function-functions #'help-fns--interactive-only)
 698 (add-hook 'help-fns-describe-function-functions #'help-fns--parent-mode)
 699 (add-hook 'help-fns-describe-function-functions #'help-fns--compiler-macro)
 700
 701 \f
 702 ;; Variables
 703
 704 ;;;###autoload
 705 (defun variable-at-point (&optional any-symbol)
 706   "Return the bound variable symbol found at or before point.
 707 Return 0 if there is no such symbol.
 708 If ANY-SYMBOL is non-nil, don't insist the symbol be bound."
 709   (with-syntax-table emacs-lisp-mode-syntax-table
 710     (or (condition-case ()
 711             (save-excursion
 712               (skip-chars-forward "'")
 713               (or (not (zerop (skip-syntax-backward "_w")))
 714                   (eq (char-syntax (following-char)) ?w)
 715                   (eq (char-syntax (following-char)) ?_)
 716                   (forward-sexp -1))
 717               (skip-chars-forward "'")
 718               (let ((obj (read (current-buffer))))
 719                 (and (symbolp obj) (boundp obj) obj)))
 720           (error nil))
 721         (let* ((str (find-tag-default))
 722                (sym (if str (intern-soft str))))
 723           (if (and sym (or any-symbol (boundp sym)))
 724               sym
 725             (save-match-data
 726               (when (and str (string-match "\\`\\W*\\(.*?\\)\\W*\\'" str))
 727                 (setq sym (intern-soft (match-string 1 str)))
 728                 (and (or any-symbol (boundp sym)) sym)))))
 729         0)))
 730
 731 (defun describe-variable-custom-version-info (variable)
 732   (let ((custom-version (get variable 'custom-version))
 733         (cpv (get variable 'custom-package-version))
 734         (output nil))
 735     (if custom-version
 736         (setq output
 737               (format "This variable was introduced, or its default value was changed, in\nversion %s of Emacs.\n"
 738                       custom-version))
 739       (when cpv
 740         (let* ((package (car-safe cpv))
 741                (version (if (listp (cdr-safe cpv))
 742                             (car (cdr-safe cpv))
 743                           (cdr-safe cpv)))
 744                (pkg-versions (assq package customize-package-emacs-version-alist))
 745                (emacsv (cdr (assoc version pkg-versions))))
 746           (if (and package version)
 747               (setq output
 748                     (format (concat "This variable was introduced, or its default value was changed, in\nversion %s of the %s package"
 749                                     (if emacsv
 750                                         (format " that is part of Emacs %s" emacsv))
 751                                     ".\n")
 752                             version package))))))
 753     output))
 754
 755 ;;;###autoload
 756 (defun describe-variable (variable &optional buffer frame)
 757   "Display the full documentation of VARIABLE (a symbol).
 758 Returns the documentation as a string, also.
 759 If VARIABLE has a buffer-local value in BUFFER or FRAME
 760 \(default to the current buffer and current frame),
 761 it is displayed along with the global value."
 762   (interactive
 763    (let ((v (variable-at-point))
 764          (enable-recursive-minibuffers t)
 765          (orig-buffer (current-buffer))
 766          val)
 767      (setq val (completing-read
 768                 (if (symbolp v)
 769                     (format
 770                      "Describe variable (default %s): " v)
 771                   "Describe variable: ")
 772                 #'help--symbol-completion-table
 773                 (lambda (vv)
 774                   ;; In case the variable only exists in the buffer
 775                   ;; the command we switch back to that buffer before
 776                   ;; we examine the variable.
 777                   (with-current-buffer orig-buffer
 778                     (or (get vv 'variable-documentation)
 779                         (and (boundp vv) (not (keywordp vv))))))
 780                 t nil nil
 781                 (if (symbolp v) (symbol-name v))))
 782      (list (if (equal val "")
 783                v (intern val)))))
 784   (let (file-name)
 785     (unless (buffer-live-p buffer) (setq buffer (current-buffer)))
 786     (unless (frame-live-p frame) (setq frame (selected-frame)))
 787     (if (not (symbolp variable))
 788         (message "You did not specify a variable")
 789       (save-excursion
 790         (let ((valvoid (not (with-current-buffer buffer (boundp variable))))
 791               (permanent-local (get variable 'permanent-local))
 792               val val-start-pos locus)
 793           ;; Extract the value before setting up the output buffer,
 794           ;; in case `buffer' *is* the output buffer.
 795           (unless valvoid
 796             (with-selected-frame frame
 797               (with-current-buffer buffer
 798                 (setq val (symbol-value variable)
 799                       locus (variable-binding-locus variable)))))
 800           (help-setup-xref (list #'describe-variable variable buffer)
 801                            (called-interactively-p 'interactive))
 802           (with-help-window (help-buffer)
 803             (with-current-buffer buffer
 804               (prin1 variable)
 805               (setq file-name (find-lisp-object-file-name variable 'defvar))
 806
 807               (if file-name
 808                   (progn
 809                     (princ (format-message
 810                             " is a variable defined in `%s'.\n"
 811                             (if (eq file-name 'C-source)
 812                                 "C source code"
 813                               (file-name-nondirectory file-name))))
 814                     (with-current-buffer standard-output
 815                       (save-excursion
 816                         (re-search-backward (substitute-command-keys
 817                                              "`\\([^`']+\\)'")
 818                                             nil t)
 819                         (help-xref-button 1 'help-variable-def
 820                                           variable file-name)))
 821                     (if valvoid
 822                         (princ "It is void as a variable.")
 823                       (princ "Its ")))
 824                 (if valvoid
 825                     (princ " is void as a variable.")
 826                   (princ (substitute-command-keys "'s ")))))
 827             (unless valvoid
 828               (with-current-buffer standard-output
 829                 (setq val-start-pos (point))
 830                 (princ "value is")
 831                 (let ((line-beg (line-beginning-position))
 832                       (print-rep
 833                        (let ((rep
 834                               (let ((print-quoted t))
 835                                 (prin1-to-string val))))
 836                          (if (and (symbolp val) (not (booleanp val)))
 837                              (format-message "`%s'" rep)
 838                            rep))))
 839                   (if (< (+ (length print-rep) (point) (- line-beg)) 68)
 840                       (insert " " print-rep)
 841                     (terpri)
 842                     (pp val)
 843                     ;; Remove trailing newline.
 844                     (delete-char -1))
 845                   (let* ((sv (get variable 'standard-value))
 846                          (origval (and (consp sv)
 847                                        (condition-case nil
 848                                            (eval (car sv))
 849                                          (error :help-eval-error))))
 850                          from)
 851                     (when (and (consp sv)
 852                                (not (equal origval val))
 853                                (not (equal origval :help-eval-error)))
 854                       (princ "\nOriginal value was \n")
 855                       (setq from (point))
 856                       (pp origval)
 857                       (if (< (point) (+ from 20))
 858                           (delete-region (1- from) from)))))))
 859             (terpri)
 860             (when locus
 861               (cond
 862                ((bufferp locus)
 863                 (princ (format "Local in buffer %s; "
 864                                (buffer-name buffer))))
 865                ((framep locus)
 866                 (princ (format "It is a frame-local variable; ")))
 867                ((terminal-live-p locus)
 868                 (princ (format "It is a terminal-local variable; ")))
 869                (t
 870                 (princ (format "It is local to %S" locus))))
 871               (if (not (default-boundp variable))
 872                   (princ "globally void")
 873                 (let ((global-val (default-value variable)))
 874                   (with-current-buffer standard-output
 875                     (princ "global value is ")
 876                     (if (eq val global-val)
 877                         (princ "the same.")
 878                       (terpri)
 879                       ;; Fixme: pp can take an age if you happen to
 880                       ;; ask for a very large expression.  We should
 881                       ;; probably print it raw once and check it's a
 882                       ;; sensible size before prettyprinting.  -- fx
 883                       (let ((from (point)))
 884                         (pp global-val)
 885                         ;; See previous comment for this function.
 886                         ;; (help-xref-on-pp from (point))
 887                         (if (< (point) (+ from 20))
 888                             (delete-region (1- from) from)))))))
 889               (terpri))
 890
 891             ;; If the value is large, move it to the end.
 892             (with-current-buffer standard-output
 893               (when (> (count-lines (point-min) (point-max)) 10)
 894                 ;; Note that setting the syntax table like below
 895                 ;; makes forward-sexp move over a `'s' at the end
 896                 ;; of a symbol.
 897                 (set-syntax-table emacs-lisp-mode-syntax-table)
 898                 (goto-char val-start-pos)
 899                 ;; The line below previously read as
 900                 ;; (delete-region (point) (progn (end-of-line) (point)))
 901                 ;; which suppressed display of the buffer local value for
 902                 ;; large values.
 903                 (when (looking-at "value is") (replace-match ""))
 904                 (save-excursion
 905                   (insert "\n\nValue:")
 906                   (set (make-local-variable 'help-button-cache)
 907                        (point-marker)))
 908                 (insert "value is shown ")
 909                 (insert-button "below"
 910                                'action help-button-cache
 911                                'follow-link t
 912                                'help-echo "mouse-2, RET: show value")
 913                 (insert ".\n")))
 914             (terpri)
 915
 916             (let* ((alias (condition-case nil
 917                               (indirect-variable variable)
 918                             (error variable)))
 919                    (obsolete (get variable 'byte-obsolete-variable))
 920                    (use (car obsolete))
 921                    (safe-var (get variable 'safe-local-variable))
 922                    (doc (or (documentation-property
 923                              variable 'variable-documentation)
 924                             (documentation-property
 925                              alias 'variable-documentation)))
 926                    (extra-line nil))
 927
 928               ;; Mention if it's a local variable.
 929               (cond
 930                ((and (local-variable-if-set-p variable)
 931                      (or (not (local-variable-p variable))
 932                          (with-temp-buffer
 933                            (local-variable-if-set-p variable))))
 934                 (setq extra-line t)
 935                 (princ "  Automatically becomes ")
 936                 (if permanent-local
 937                     (princ "permanently "))
 938                 (princ "buffer-local when set.\n"))
 939                ((not permanent-local))
 940                ((bufferp locus)
 941                 (setq extra-line t)
 942                 (princ
 943                  (substitute-command-keys
 944                   "  This variable's buffer-local value is permanent.\n")))
 945                (t
 946                 (setq extra-line t)
 947                 (princ (substitute-command-keys
 948                         "  This variable's value is permanent \
 949 if it is given a local binding.\n"))))
 950
 951               ;; Mention if it's an alias.
 952               (unless (eq alias variable)
 953                 (setq extra-line t)
 954                 (princ (format-message
 955                         "  This variable is an alias for `%s'.\n"
 956                         alias)))
 957
 958               (when obsolete
 959                 (setq extra-line t)
 960                 (princ "  This variable is obsolete")
 961                 (if (nth 2 obsolete)
 962                     (princ (format " since %s" (nth 2 obsolete))))
 963                 (princ (cond ((stringp use) (concat ";\n  " use))
 964                              (use (format-message ";\n  use `%s' instead."
 965                                                   (car obsolete)))
 966                              (t ".")))
 967                 (terpri))
 968
 969               (when (member (cons variable val)
 970                             (with-current-buffer buffer
 971                               file-local-variables-alist))
 972                 (setq extra-line t)
 973                 (if (member (cons variable val)
 974                              (with-current-buffer buffer
 975                                dir-local-variables-alist))
 976                     (let ((file (and (buffer-file-name buffer)
 977                                       (not (file-remote-p
 978                                             (buffer-file-name buffer)))
 979                                       (dir-locals-find-file
 980                                        (buffer-file-name buffer))))
 981                           (is-directory nil))
 982                       (princ (substitute-command-keys
 983                               "  This variable's value is directory-local"))
 984                       (when (consp file) ; result from cache
 985                         ;; If the cache element has an mtime, we
 986                         ;; assume it came from a file.
 987                         (if (nth 2 file)
 988                             ;; (car file) is a directory.
 989                             (setq file (dir-locals--all-files (car file)))
 990                           ;; Otherwise, assume it was set directly.
 991                           (setq file (car file)
 992                                 is-directory t)))
 993                       (if (null file)
 994                           (princ ".\n")
 995                         (princ ", set ")
 996                         (princ (substitute-command-keys
 997                                 (cond
 998                                  (is-directory "for the directory\n  `")
 999                                  ;; Many files matched.
1000                                  ((and (consp file) (cdr file))
1001                                   (setq file (file-name-directory (car file)))
1002                                   (format "by one of the\n  %s files in the directory\n  `"
1003                                           dir-locals-file))
1004                                  (t (setq file (car file))
1005                                     "by the file\n  `"))))
1006                         (with-current-buffer standard-output
1007                           (insert-text-button
1008                            file 'type 'help-dir-local-var-def
1009                              'help-args (list variable file)))
1010                         (princ (substitute-command-keys "'.\n"))))
1011                   (princ (substitute-command-keys
1012                           "  This variable's value is file-local.\n"))))
1013
1014               (when (memq variable ignored-local-variables)
1015                 (setq extra-line t)
1016                 (princ "  This variable is ignored as a file-local \
1017 variable.\n"))
1018
1019               ;; Can be both risky and safe, eg auto-fill-function.
1020               (when (risky-local-variable-p variable)
1021                 (setq extra-line t)
1022                 (princ "  This variable may be risky if used as a \
1023 file-local variable.\n")
1024                 (when (assq variable safe-local-variable-values)
1025                   (princ (substitute-command-keys
1026                           "  However, you have added it to \
1027 `safe-local-variable-values'.\n"))))
1028
1029               (when safe-var
1030                 (setq extra-line t)
1031                 (princ "  This variable is safe as a file local variable ")
1032                 (princ "if its value\n  satisfies the predicate ")
1033                 (princ (if (byte-code-function-p safe-var)
1034                            "which is a byte-compiled expression.\n"
1035                          (format-message "`%s'.\n" safe-var))))
1036
1037               (if extra-line (terpri))
1038               (princ "Documentation:\n")
1039               (with-current-buffer standard-output
1040                 (insert (or doc "Not documented as a variable."))))
1041
1042             ;; Make a link to customize if this variable can be customized.
1043             (when (custom-variable-p variable)
1044               (let ((customize-label "customize"))
1045                 (terpri)
1046                 (terpri)
1047                 (princ (concat "You can " customize-label " this variable."))
1048                 (with-current-buffer standard-output
1049                   (save-excursion
1050                     (re-search-backward
1051                      (concat "\\(" customize-label "\\)") nil t)
1052                     (help-xref-button 1 'help-customize-variable variable))))
1053               ;; Note variable's version or package version.
1054               (let ((output (describe-variable-custom-version-info variable)))
1055                 (when output
1056                   (terpri)
1057                   (terpri)
1058                   (princ output))))
1059
1060             (with-current-buffer standard-output
1061               ;; Return the text we displayed.
1062               (buffer-string))))))))
1063
1064
1065 (defvar help-xref-stack-item)
1066
1067 ;;;###autoload
1068 (defun describe-symbol (symbol &optional buffer frame)
1069   "Display the full documentation of SYMBOL.
1070 Will show the info of SYMBOL as a function, variable, and/or face.
1071 Optional arguments BUFFER and FRAME specify for which buffer and
1072 frame to show the information about SYMBOL; they default to the
1073 current buffer and the selected frame, respectively."
1074   (interactive
1075    (let* ((v-or-f (symbol-at-point))
1076           (found (cl-some (lambda (x) (funcall (nth 1 x) v-or-f))
1077                           describe-symbol-backends))
1078           (v-or-f (if found v-or-f (function-called-at-point)))
1079           (found (or found v-or-f))
1080           (enable-recursive-minibuffers t)
1081           (val (completing-read (if found
1082                                     (format
1083                                      "Describe symbol (default %s): " v-or-f)
1084                                   "Describe symbol: ")
1085                                 obarray
1086                                 (lambda (vv)
1087                                   (cl-some (lambda (x) (funcall (nth 1 x) vv))
1088                                            describe-symbol-backends))
1089                                 t nil nil
1090                                 (if found (symbol-name v-or-f)))))
1091      (list (if (equal val "")
1092                v-or-f (intern val)))))
1093   (if (not (symbolp symbol))
1094       (user-error "You didn't specify a function or variable"))
1095   (unless (buffer-live-p buffer) (setq buffer (current-buffer)))
1096   (unless (frame-live-p frame) (setq frame (selected-frame)))
1097   (with-current-buffer (help-buffer)
1098     ;; Push the previous item on the stack before clobbering the output buffer.
1099     (help-setup-xref nil nil)
1100     (let* ((docs
1101             (nreverse
1102              (delq nil
1103                    (mapcar (pcase-lambda (`(,name ,testfn ,descfn))
1104                              (when (funcall testfn symbol)
1105                                ;; Don't record the current entry in the stack.
1106                                (setq help-xref-stack-item nil)
1107                                (cons name
1108                                      (funcall descfn symbol buffer frame))))
1109                            describe-symbol-backends))))
1110            (single (null (cdr docs))))
1111       (while (cdr docs)
1112         (goto-char (point-min))
1113         (let ((inhibit-read-only t)
1114               (name (caar docs))        ;Name of doc currently at BOB.
1115               (doc (cdr (cadr docs))))  ;Doc to add at BOB.
1116           (when doc
1117             (insert doc)
1118             (delete-region (point)
1119                            (progn (skip-chars-backward " \t\n") (point)))
1120             (insert "\n\n"
1121                     (eval-when-compile
1122                       (propertize "\n" 'face '(:height 0.1 :inverse-video t)))
1123                     "\n")
1124             (when name
1125               (insert (symbol-name symbol)
1126                       " is also a " name "." "\n\n"))))
1127         (setq docs (cdr docs)))
1128       (unless single
1129         ;; Don't record the `describe-variable' item in the stack.
1130         (setq help-xref-stack-item nil)
1131         (help-setup-xref (list #'describe-symbol symbol) nil))
1132       (goto-char (point-min)))))
1133
1134 ;;;###autoload
1135 (defun describe-syntax (&optional buffer)
1136   "Describe the syntax specifications in the syntax table of BUFFER.
1137 The descriptions are inserted in a help buffer, which is then displayed.
1138 BUFFER defaults to the current buffer."
1139   (interactive)
1140   (setq buffer (or buffer (current-buffer)))
1141   (help-setup-xref (list #'describe-syntax buffer)
1142                    (called-interactively-p 'interactive))
1143   (with-help-window (help-buffer)
1144     (let ((table (with-current-buffer buffer (syntax-table))))
1145       (with-current-buffer standard-output
1146         (describe-vector table 'internal-describe-syntax-value)
1147         (while (setq table (char-table-parent table))
1148           (insert "\nThe parent syntax table is:")
1149           (describe-vector table 'internal-describe-syntax-value))))))
1150
1151 (defun help-describe-category-set (value)
1152   (insert (cond
1153            ((null value) "default")
1154            ((char-table-p value) "deeper char-table ...")
1155            (t (condition-case nil
1156                   (category-set-mnemonics value)
1157                 (error "invalid"))))))
1158
1159 ;;;###autoload
1160 (defun describe-categories (&optional buffer)
1161   "Describe the category specifications in the current category table.
1162 The descriptions are inserted in a buffer, which is then displayed.
1163 If BUFFER is non-nil, then describe BUFFER's category table instead.
1164 BUFFER should be a buffer or a buffer name."
1165   (interactive)
1166   (setq buffer (or buffer (current-buffer)))
1167   (help-setup-xref (list #'describe-categories buffer)
1168                    (called-interactively-p 'interactive))
1169   (with-help-window (help-buffer)
1170     (let* ((table (with-current-buffer buffer (category-table)))
1171            (docs (char-table-extra-slot table 0)))
1172       (if (or (not (vectorp docs)) (/= (length docs) 95))
1173           (error "Invalid first extra slot in this category table\n"))
1174       (with-current-buffer standard-output
1175         (setq-default help-button-cache (make-marker))
1176         (insert "Legend of category mnemonics ")
1177         (insert-button "(longer descriptions at the bottom)"
1178                        'action help-button-cache
1179                        'follow-link t
1180                        'help-echo "mouse-2, RET: show full legend")
1181         (insert "\n")
1182         (let ((pos (point)) (items 0) lines n)
1183           (dotimes (i 95)
1184             (if (aref docs i) (setq items (1+ items))))
1185           (setq lines (1+ (/ (1- items) 4)))
1186           (setq n 0)
1187           (dotimes (i 95)
1188             (let ((elt (aref docs i)))
1189               (when elt
1190                 (string-match ".*" elt)
1191                 (setq elt (match-string 0 elt))
1192                 (if (>= (length elt) 17)
1193                     (setq elt (concat (substring elt 0 14) "...")))
1194                 (if (< (point) (point-max))
1195                     (move-to-column (* 20 (/ n lines)) t))
1196                 (insert (+ i ?\s) ?: elt)
1197                 (if (< (point) (point-max))
1198                     (forward-line 1)
1199                   (insert "\n"))
1200                 (setq n (1+ n))
1201                 (if (= (% n lines) 0)
1202                     (goto-char pos))))))
1203         (goto-char (point-max))
1204         (insert "\n"
1205                 "character(s)\tcategory mnemonics\n"
1206                 "------------\t------------------")
1207         (describe-vector table 'help-describe-category-set)
1208         (set-marker help-button-cache (point))
1209         (insert "Legend of category mnemonics:\n")
1210         (dotimes (i 95)
1211           (let ((elt (aref docs i)))
1212             (when elt
1213               (if (string-match "\n" elt)
1214                   (setq elt (substring elt (match-end 0))))
1215               (insert (+ i ?\s) ": " elt "\n"))))
1216         (while (setq table (char-table-parent table))
1217           (insert "\nThe parent category table is:")
1218           (describe-vector table 'help-describe-category-set))))))
1219
1220 \f
1221 ;;; Replacements for old lib-src/ programs.  Don't seem especially useful.
1222
1223 ;; Replaces lib-src/digest-doc.c.
1224 ;;;###autoload
1225 (defun doc-file-to-man (file)
1226   "Produce an nroff buffer containing the doc-strings from the DOC file."
1227   (interactive (list (read-file-name "Name of DOC file: " doc-directory
1228                                      internal-doc-file-name t)))
1229   (or (file-readable-p file)
1230       (error "Cannot read file `%s'" file))
1231   (pop-to-buffer (generate-new-buffer "*man-doc*"))
1232   (setq buffer-undo-list t)
1233   (insert ".TH \"Command Summary for GNU Emacs\"\n"
1234           ".AU Richard M. Stallman\n")
1235   (insert-file-contents file)
1236   (let (notfirst)
1237     (while (search-forward "\1f" nil 'move)
1238       (if (looking-at "S")
1239           (delete-region (1- (point)) (line-end-position))
1240         (delete-char -1)
1241         (if notfirst
1242             (insert "\n.DE\n")
1243           (setq notfirst t))
1244         (insert "\n.SH ")
1245         (insert (if (looking-at "F") "Function " "Variable "))
1246         (delete-char 1)
1247         (forward-line 1)
1248         (insert ".DS L\n"))))
1249   (insert "\n.DE\n")
1250   (setq buffer-undo-list nil)
1251   (nroff-mode))
1252
1253 ;; Replaces lib-src/sorted-doc.c.
1254 ;;;###autoload
1255 (defun doc-file-to-info (file)
1256   "Produce a texinfo buffer with sorted doc-strings from the DOC file."
1257   (interactive (list (read-file-name "Name of DOC file: " doc-directory
1258                                      internal-doc-file-name t)))
1259   (or (file-readable-p file)
1260       (error "Cannot read file `%s'" file))
1261   (let ((i 0) type name doc alist)
1262     (with-temp-buffer
1263       (insert-file-contents file)
1264       ;; The characters "@{}" need special treatment.
1265       (while (re-search-forward "[@{}]" nil t)
1266         (backward-char)
1267         (insert "@")
1268         (forward-char 1))
1269       (goto-char (point-min))
1270       (while (search-forward "\1f" nil t)
1271         (unless (looking-at "S")
1272           (setq type (char-after)
1273                 name (buffer-substring (1+ (point)) (line-end-position))
1274                 doc (buffer-substring (line-beginning-position 2)
1275                                       (if (search-forward  "\1f" nil 'move)
1276                                           (1- (point))
1277                                         (point)))
1278                 alist (cons (list name type doc) alist))
1279           (backward-char 1))))
1280     (pop-to-buffer (generate-new-buffer "*info-doc*"))
1281     (setq buffer-undo-list t)
1282     ;; Write the output header.
1283     (insert "\\input texinfo  @c -*-texinfo-*-\n"
1284             "@setfilename emacsdoc.info\n"
1285             "@settitle Command Summary for GNU Emacs\n"
1286             "@finalout\n"
1287             "\n@node Top\n"
1288             "@unnumbered Command Summary for GNU Emacs\n\n"
1289             "@table @asis\n\n"
1290             "@iftex\n"
1291             "@global@let@ITEM@item\n"
1292             "@def@item{@filbreak@vskip5pt@ITEM}\n"
1293             "@font@tensy cmsy10 scaled @magstephalf\n"
1294             "@font@teni cmmi10 scaled @magstephalf\n"
1295             "@def\\{{@tensy@char110}}\n" ; this backslash goes with cmr10
1296             "@def|{{@tensy@char106}}\n"
1297             "@def@{{{@tensy@char102}}\n"
1298             "@def@}{{@tensy@char103}}\n"
1299             "@def<{{@teni@char62}}\n"
1300             "@def>{{@teni@char60}}\n"
1301             "@chardef@@64\n"
1302             "@catcode43=12\n"
1303             "@tableindent-0.2in\n"
1304             "@end iftex\n")
1305     ;; Sort the array by name; within each name, by type (functions first).
1306     (setq alist (sort alist (lambda (e1 e2)
1307                               (if (string-equal (car e1) (car e2))
1308                                   (<= (cadr e1) (cadr e2))
1309                                 (string-lessp (car e1) (car e2))))))
1310     ;; Print each function.
1311     (dolist (e alist)
1312       (insert "\n@item "
1313               (if (char-equal (cadr e) ?\F) "Function" "Variable")
1314               " @code{" (car e) "}\n@display\n"
1315               (nth 2 e)
1316               "\n@end display\n")
1317       ;; Try to avoid a save size overflow in the TeX output routine.
1318       (if (zerop (setq i (% (1+ i) 100)))
1319           (insert "\n@end table\n@table @asis\n")))
1320     (insert "@end table\n"
1321             "@bye\n")
1322     (setq buffer-undo-list nil)
1323     (texinfo-mode)))
1324
1325 (provide 'help-fns)
1326
1327 ;;; help-fns.el ends here