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 When called from lisp, FUNCTION may also be a function object."
 111   (interactive
 112    (let* ((fn (function-called-at-point))
 113           (enable-recursive-minibuffers t)
 114           (val (completing-read
 115                 (if fn
 116                     (format "Describe function (default %s): " fn)
 117                   "Describe function: ")
 118                 #'help--symbol-completion-table #'fboundp t nil nil
 119                 (and fn (symbol-name fn)))))
 120      (unless (equal val "")
 121        (setq fn (intern val)))
 122      (unless (and fn (symbolp fn))
 123        (user-error "You didn't specify a function symbol"))
 124      (unless (fboundp fn)
 125        (user-error "Symbol's function definition is void: %s" fn))
 126      (list fn)))
 127
 128   ;; We save describe-function-orig-buffer on the help xref stack, so
 129   ;; it is restored by the back/forward buttons.  'help-buffer'
 130   ;; expects (current-buffer) to be a help buffer when processing
 131   ;; those buttons, so we can't change the current buffer before
 132   ;; calling that.
 133   (let ((describe-function-orig-buffer
 134          (or describe-function-orig-buffer
 135              (current-buffer))))
 136
 137     (help-setup-xref
 138      (list (lambda (function buffer)
 139              (let ((describe-function-orig-buffer
 140                     (if (buffer-live-p buffer) buffer)))
 141                (describe-function function)))
 142            function describe-function-orig-buffer)
 143      (called-interactively-p 'interactive))
 144
 145     (save-excursion
 146       (with-help-window (help-buffer)
 147         (prin1 function)
 148         ;; Use " is " instead of a colon so that
 149         ;; it is easier to get out the function name using forward-sexp.
 150         (princ " is ")
 151         (describe-function-1 function)
 152         (with-current-buffer standard-output
 153           ;; Return the text we displayed.
 154           (buffer-string))))
 155     ))
 156
 157
 158 ;; Could be this, if we make symbol-file do the work below.
 159 ;; (defun help-C-file-name (subr-or-var kind)
 160 ;;   "Return the name of the C file where SUBR-OR-VAR is defined.
 161 ;; KIND should be `var' for a variable or `subr' for a subroutine."
 162 ;;   (symbol-file (if (symbolp subr-or-var) subr-or-var
 163 ;;               (subr-name subr-or-var))
 164 ;;             (if (eq kind 'var) 'defvar 'defun)))
 165 ;;;###autoload
 166 (defun help-C-file-name (subr-or-var kind)
 167   "Return the name of the C file where SUBR-OR-VAR is defined.
 168 KIND should be `var' for a variable or `subr' for a subroutine."
 169   (let ((docbuf (get-buffer-create " *DOC*"))
 170         (name (if (eq 'var kind)
 171                   (concat "V" (symbol-name subr-or-var))
 172                 (concat "F" (subr-name (advice--cd*r subr-or-var))))))
 173     (with-current-buffer docbuf
 174       (goto-char (point-min))
 175       (if (eobp)
 176           (insert-file-contents-literally
 177            (expand-file-name internal-doc-file-name doc-directory)))
 178       (let ((file (catch 'loop
 179                     (while t
 180                       (let ((pnt (search-forward (concat "\x1f" name "\n"))))
 181                         (re-search-backward "\x1fS\\(.*\\)")
 182                         (let ((file (match-string 1)))
 183                           (if (member file build-files)
 184                               (throw 'loop file)
 185                             (goto-char pnt))))))))
 186         (if (string-match "^ns.*\\(\\.o\\|obj\\)\\'" file)
 187             (setq file (replace-match ".m" t t file 1))
 188           (if (string-match "\\.\\(o\\|obj\\)\\'" file)
 189               (setq file (replace-match ".c" t t file))))
 190         (if (string-match "\\.\\(c\\|m\\)\\'" file)
 191             (concat "src/" file)
 192           file)))))
 193
 194 (defcustom help-downcase-arguments nil
 195   "If non-nil, argument names in *Help* buffers are downcased."
 196   :type 'boolean
 197   :group 'help
 198   :version "23.2")
 199
 200 (defun help-highlight-arg (arg)
 201   "Highlight ARG as an argument name for a *Help* buffer.
 202 Return ARG in face `help-argument-name'; ARG is also downcased
 203 if the variable `help-downcase-arguments' is non-nil."
 204   (propertize (if help-downcase-arguments (downcase arg) arg)
 205               'face 'help-argument-name))
 206
 207 (defun help-do-arg-highlight (doc args)
 208   (with-syntax-table (make-syntax-table emacs-lisp-mode-syntax-table)
 209     (modify-syntax-entry ?\- "w")
 210     (dolist (arg args)
 211       (setq doc (replace-regexp-in-string
 212                  ;; This is heuristic, but covers all common cases
 213                  ;; except ARG1-ARG2
 214                  (concat "\\<"                   ; beginning of word
 215                          "\\(?:[a-z-]*-\\)?"     ; for xxx-ARG
 216                          "\\("
 217                          (regexp-quote arg)
 218                          "\\)"
 219                          "\\(?:es\\|s\\|th\\)?"  ; for ARGth, ARGs
 220                          "\\(?:-[a-z0-9-]+\\)?"  ; for ARG-xxx, ARG-n
 221                          "\\(?:-[{([<`\"‘].*?\\)?"; for ARG-{x}, (x), <x>, [x], `x', ‘x’
 222                          "\\>")                  ; end of word
 223                  (help-highlight-arg arg)
 224                  doc t t 1)))
 225     doc))
 226
 227 (defun help-highlight-arguments (usage doc &rest args)
 228   (when (and usage (string-match "^(" usage))
 229     (with-temp-buffer
 230       (insert usage)
 231       (goto-char (point-min))
 232       (let ((case-fold-search nil)
 233             (next (not (or args (looking-at "\\["))))
 234             (opt nil))
 235         ;; Make a list of all arguments
 236         (skip-chars-forward "^ ")
 237         (while next
 238           (or opt (not (looking-at " &")) (setq opt t))
 239           (if (not (re-search-forward " \\([\\[(]*\\)\\([^] &).]+\\)" nil t))
 240               (setq next nil)
 241             (setq args (cons (match-string 2) args))
 242             (when (and opt (string= (match-string 1) "("))
 243               ;; A pesky CL-style optional argument with default value,
 244               ;; so let's skip over it
 245               (search-backward "(")
 246               (goto-char (scan-sexps (point) 1)))))
 247         ;; Highlight arguments in the USAGE string
 248         (setq usage (help-do-arg-highlight (buffer-string) args))
 249         ;; Highlight arguments in the DOC string
 250         (setq doc (and doc (help-do-arg-highlight doc args))))))
 251   ;; Return value is like the one from help-split-fundoc, but highlighted
 252   (cons usage doc))
 253
 254 ;; The following function was compiled from the former functions
 255 ;; `describe-simplify-lib-file-name' and `find-source-lisp-file' with
 256 ;; some excerpts from `describe-function-1' and `describe-variable'.
 257 ;; The only additional twists provided are (1) locate the defining file
 258 ;; for autoloaded functions, and (2) give preference to files in the
 259 ;; "install directory" (directories found via `load-path') rather than
 260 ;; to files in the "compile directory" (directories found by searching
 261 ;; the loaddefs.el file).  We autoload it because it's also used by
 262 ;; `describe-face' (instead of `describe-simplify-lib-file-name').
 263
 264 ;;;###autoload
 265 (defun find-lisp-object-file-name (object type)
 266   "Guess the file that defined the Lisp object OBJECT, of type TYPE.
 267 OBJECT should be a symbol associated with a function, variable, or face;
 268   alternatively, it can be a function definition.
 269 If TYPE is `defvar', search for a variable definition.
 270 If TYPE is `defface', search for a face definition.
 271 If TYPE is not a symbol, search for a function definition.
 272
 273 The return value is the absolute name of a readable file where OBJECT is
 274 defined.  If several such files exist, preference is given to a file
 275 found via `load-path'.  The return value can also be `C-source', which
 276 means that OBJECT is a function or variable defined in C.  If no
 277 suitable file is found, return nil."
 278   (let* ((autoloaded (autoloadp type))
 279          (file-name (or (and autoloaded (nth 1 type))
 280                         (symbol-file
 281                          ;; FIXME: Why do we have this weird "If TYPE is the
 282                          ;; value returned by `symbol-function' for a function
 283                          ;; symbol" exception?
 284                          object (or (if (symbolp type) type) 'defun)))))
 285     (cond
 286      (autoloaded
 287       ;; An autoloaded function: Locate the file since `symbol-function'
 288       ;; has only returned a bare string here.
 289       (setq file-name
 290             (locate-file file-name load-path '(".el" ".elc") 'readable)))
 291      ((and (stringp file-name)
 292            (string-match "[.]*loaddefs.el\\'" file-name))
 293       ;; An autoloaded variable or face.  Visit loaddefs.el in a buffer
 294       ;; and try to extract the defining file.  The following form is
 295       ;; from `describe-function-1' and `describe-variable'.
 296       (let ((location
 297              (condition-case nil
 298                  (find-function-search-for-symbol object nil file-name)
 299                (error nil))))
 300         (when (cdr location)
 301           (with-current-buffer (car location)
 302             (goto-char (cdr location))
 303             (when (re-search-backward
 304                    "^;;; Generated autoloads from \\(.*\\)" nil t)
 305               (setq file-name
 306                     (locate-file
 307                      (file-name-sans-extension
 308                       (match-string-no-properties 1))
 309                      load-path '(".el" ".elc") 'readable))))))))
 310
 311     (cond
 312      ((and (not file-name) (subrp type))
 313       ;; A built-in function.  The form is from `describe-function-1'.
 314       (if (get-buffer " *DOC*")
 315           (help-C-file-name type 'subr)
 316         'C-source))
 317      ((and (not file-name) (symbolp object)
 318            (integerp (get object 'variable-documentation)))
 319       ;; A variable defined in C.  The form is from `describe-variable'.
 320       (if (get-buffer " *DOC*")
 321           (help-C-file-name object 'var)
 322         'C-source))
 323      ((not (stringp file-name))
 324       ;; If we don't have a file-name string by now, we lost.
 325       nil)
 326      ;; Now, `file-name' should have become an absolute file name.
 327      ;; For files loaded from ~/.foo.elc, try ~/.foo.
 328      ;; This applies to config files like ~/.emacs,
 329      ;; which people sometimes compile.
 330      ((let (fn)
 331         (and (string-match "\\`\\..*\\.elc\\'"
 332                            (file-name-nondirectory file-name))
 333              (string-equal (file-name-directory file-name)
 334                            (file-name-as-directory (expand-file-name "~")))
 335              (file-readable-p (setq fn (file-name-sans-extension file-name)))
 336              fn)))
 337      ;; When the Elisp source file can be found in the install
 338      ;; directory, return the name of that file.
 339      ((let ((lib-name
 340              (if (string-match "[.]elc\\'" file-name)
 341                  (substring-no-properties file-name 0 -1)
 342                file-name)))
 343         (or (and (file-readable-p lib-name) lib-name)
 344             ;; The library might be compressed.
 345             (and (file-readable-p (concat lib-name ".gz")) lib-name))))
 346      ((let* ((lib-name (file-name-nondirectory file-name))
 347              ;; The next form is from `describe-simplify-lib-file-name'.
 348              (file-name
 349               ;; Try converting the absolute file name to a library
 350               ;; name, convert that back to a file name and see if we
 351               ;; get the original one.  If so, they are equivalent.
 352               (if (equal file-name (locate-file lib-name load-path '("")))
 353                   (if (string-match "[.]elc\\'" lib-name)
 354                       (substring-no-properties lib-name 0 -1)
 355                     lib-name)
 356                 file-name))
 357              (src-file (locate-library file-name t nil 'readable)))
 358         (and src-file (file-readable-p src-file) src-file))))))
 359
 360 (defun help-fns--key-bindings (function)
 361   (when (commandp function)
 362     (let ((pt2 (with-current-buffer standard-output (point)))
 363           (remapped (command-remapping function)))
 364       (unless (memq remapped '(ignore undefined))
 365         (let ((keys (where-is-internal
 366                      (or remapped function) overriding-local-map nil nil))
 367               non-modified-keys)
 368           (if (and (eq function 'self-insert-command)
 369                    (vectorp (car-safe keys))
 370                    (consp (aref (car keys) 0)))
 371               (princ "It is bound to many ordinary text characters.\n")
 372             ;; Which non-control non-meta keys run this command?
 373             (dolist (key keys)
 374               (if (member (event-modifiers (aref key 0)) '(nil (shift)))
 375                   (push key non-modified-keys)))
 376             (when remapped
 377               (princ "Its keys are remapped to ")
 378               (princ (if (symbolp remapped)
 379                          (format-message "`%s'" remapped)
 380                        "an anonymous command"))
 381               (princ ".\n"))
 382
 383             (when keys
 384               (princ (if remapped
 385                          "Without this remapping, it would be bound to "
 386                        "It is bound to "))
 387               ;; If lots of ordinary text characters run this command,
 388               ;; don't mention them one by one.
 389               (if (< (length non-modified-keys) 10)
 390                   (princ (mapconcat 'key-description keys ", "))
 391                 (dolist (key non-modified-keys)
 392                   (setq keys (delq key keys)))
 393                 (if keys
 394                     (progn
 395                       (princ (mapconcat 'key-description keys ", "))
 396                       (princ ", and many ordinary text characters"))
 397                   (princ "many ordinary text characters"))))
 398             (when (or remapped keys non-modified-keys)
 399               (princ ".")
 400               (terpri)))))
 401
 402       (with-current-buffer standard-output
 403         (fill-region-as-paragraph pt2 (point))
 404         (unless (looking-back "\n\n" (- (point) 2))
 405           (terpri))))))
 406
 407 (defun help-fns--compiler-macro (function)
 408   (let ((handler (function-get function 'compiler-macro)))
 409     (when handler
 410       (insert "\nThis function has a compiler macro")
 411       (if (symbolp handler)
 412           (progn
 413             (insert (format-message " `%s'" handler))
 414             (save-excursion
 415               (re-search-backward (substitute-command-keys "`\\([^`']+\\)'")
 416                                   nil t)
 417               (help-xref-button 1 'help-function handler)))
 418         ;; FIXME: Obsolete since 24.4.
 419         (let ((lib (get function 'compiler-macro-file)))
 420           (when (stringp lib)
 421             (insert (format-message " in `%s'" lib))
 422             (save-excursion
 423               (re-search-backward (substitute-command-keys "`\\([^`']+\\)'")
 424                                   nil t)
 425               (help-xref-button 1 'help-function-cmacro function lib)))))
 426       (insert ".\n"))))
 427
 428 (defun help-fns--signature (function doc real-def real-function buffer)
 429   "Insert usage at point and return docstring.  With highlighting."
 430   (if (keymapp function)
 431       doc                       ; If definition is a keymap, skip arglist note.
 432     (let* ((advertised (gethash real-def advertised-signature-table t))
 433            (arglist (if (listp advertised)
 434                         advertised (help-function-arglist real-def)))
 435            (usage (help-split-fundoc doc function)))
 436       (if usage (setq doc (cdr usage)))
 437       (let* ((use (cond
 438                    ((and usage (not (listp advertised))) (car usage))
 439                    ((listp arglist)
 440                     (help--make-usage-docstring function arglist))
 441                    ((stringp arglist) arglist)
 442                    ;; Maybe the arglist is in the docstring of a symbol
 443                    ;; this one is aliased to.
 444                    ((let ((fun real-function))
 445                       (while (and (symbolp fun)
 446                                   (setq fun (symbol-function fun))
 447                                   (not (setq usage (help-split-fundoc
 448                                                     (documentation fun)
 449                                                     function)))))
 450                       usage)
 451                     (car usage))
 452                    ((or (stringp real-def)
 453                         (vectorp real-def))
 454                     (format "\nMacro: %s"
 455                             (help--docstring-quote
 456                              (format-kbd-macro real-def))))
 457                    (t "[Missing arglist.  Please make a bug report.]")))
 458              ;; Insert "`X", not "(\` X)", when documenting `X.
 459              (use1 (replace-regexp-in-string
 460                     "\\`(\\\\=\\\\\\\\=` \\([^\n ]*\\))\\'"
 461                     "\\\\=`\\1" use t))
 462              (high (if buffer
 463                        (let (subst-use1 subst-doc)
 464                          (with-current-buffer buffer
 465                            (setq subst-use1 (substitute-command-keys use1))
 466                            (setq subst-doc (substitute-command-keys doc)))
 467                          (help-highlight-arguments subst-use1 subst-doc))
 468                      (cons use1 doc))))
 469         (let ((fill-begin (point))
 470               (high-usage (car high))
 471               (high-doc (cdr high)))
 472           (insert high-usage "\n")
 473           (fill-region fill-begin (point))
 474           high-doc)))))
 475
 476 (defun help-fns--parent-mode (function)
 477   ;; If this is a derived mode, link to the parent.
 478   (let ((parent-mode (and (symbolp function)
 479                           (get function
 480                                'derived-mode-parent))))
 481     (when parent-mode
 482       (insert (substitute-command-keys "\nParent mode: `"))
 483       (let ((beg (point)))
 484         (insert (format "%s" parent-mode))
 485         (make-text-button beg (point)
 486                           'type 'help-function
 487                           'help-args (list parent-mode)))
 488       (insert (substitute-command-keys "'.\n")))))
 489
 490 (defun help-fns--obsolete (function)
 491   ;; Ignore lambda constructs, keyboard macros, etc.
 492   (let* ((obsolete (and (symbolp function)
 493                         (get function 'byte-obsolete-info)))
 494          (use (car obsolete)))
 495     (when obsolete
 496       (insert "\nThis "
 497               (if (eq (car-safe (symbol-function function)) 'macro)
 498                   "macro"
 499                 "function")
 500               " is obsolete")
 501       (when (nth 2 obsolete)
 502         (insert (format " since %s" (nth 2 obsolete))))
 503       (insert (cond ((stringp use) (concat ";\n" use))
 504                     (use (format-message ";\nuse `%s' instead." use))
 505                     (t "."))
 506               "\n"))))
 507
 508 ;; We could use `symbol-file' but this is a wee bit more efficient.
 509 (defun help-fns--autoloaded-p (function file)
 510   "Return non-nil if FUNCTION has previously been autoloaded.
 511 FILE is the file where FUNCTION was probably defined."
 512   (let* ((file (file-name-sans-extension (file-truename file)))
 513          (load-hist load-history)
 514          (target (cons t function))
 515          found)
 516     (while (and load-hist (not found))
 517       (and (caar load-hist)
 518            (equal (file-name-sans-extension (caar load-hist)) file)
 519            (setq found (member target (cdar load-hist))))
 520       (setq load-hist (cdr load-hist)))
 521     found))
 522
 523 (defun help-fns--interactive-only (function)
 524   "Insert some help blurb if FUNCTION should only be used interactively."
 525   ;; Ignore lambda constructs, keyboard macros, etc.
 526   (and (symbolp function)
 527        (not (eq (car-safe (symbol-function function)) 'macro))
 528        (let* ((interactive-only
 529                (or (get function 'interactive-only)
 530                    (if (boundp 'byte-compile-interactive-only-functions)
 531                        (memq function
 532                              byte-compile-interactive-only-functions)))))
 533          (when interactive-only
 534            (insert "\nThis function is for interactive use only"
 535                    ;; Cf byte-compile-form.
 536                    (cond ((stringp interactive-only)
 537                           (format ";\nin Lisp code %s" interactive-only))
 538                          ((and (symbolp 'interactive-only)
 539                                (not (eq interactive-only t)))
 540                           (format-message ";\nin Lisp code use `%s' instead."
 541                                           interactive-only))
 542                          (t "."))
 543                    "\n")))))
 544
 545 (defun help-fns-short-filename (filename)
 546   (let* ((abbrev (abbreviate-file-name filename))
 547          (short abbrev))
 548     (dolist (dir load-path)
 549       (let ((rel (file-relative-name filename dir)))
 550         (if (< (length rel) (length short))
 551             (setq short rel)))
 552       (let ((rel (file-relative-name abbrev dir)))
 553         (if (< (length rel) (length short))
 554             (setq short rel))))
 555     short))
 556
 557 ;;;###autoload
 558 (defun describe-function-1 (function)
 559   (let* ((advised (and (symbolp function)
 560                        (featurep 'nadvice)
 561                        (advice--p (advice--symbol-function function))))
 562          ;; If the function is advised, use the symbol that has the
 563          ;; real definition, if that symbol is already set up.
 564          (real-function
 565           (or (and advised
 566                    (advice--cd*r (advice--symbol-function function)))
 567               function))
 568          ;; Get the real definition.
 569          (def (if (symbolp real-function)
 570                   (or (symbol-function real-function)
 571                       (signal 'void-function (list real-function)))
 572                 real-function))
 573          (aliased (or (symbolp def)
 574                       ;; Advised & aliased function.
 575                       (and advised (symbolp real-function)
 576                            (not (eq 'autoload (car-safe def))))
 577                       (and (subrp def)
 578                            (not (string= (subr-name def)
 579                                          (symbol-name function))))))
 580          (real-def (cond
 581                     ((and aliased (not (subrp def)))
 582                      (let ((f real-function))
 583                        (while (and (fboundp f)
 584                                    (symbolp (symbol-function f)))
 585                          (setq f (symbol-function f)))
 586                        f))
 587                     ((subrp def) (intern (subr-name def)))
 588                     (t def)))
 589          (sig-key (if (subrp def)
 590                       (indirect-function real-def)
 591                     real-def))
 592          (file-name (find-lisp-object-file-name function (if aliased 'defun
 593                                                            def)))
 594          (pt1 (with-current-buffer (help-buffer) (point)))
 595          (beg (if (and (or (byte-code-function-p def)
 596                            (keymapp def)
 597                            (memq (car-safe def) '(macro lambda closure)))
 598                        (stringp file-name)
 599                        (help-fns--autoloaded-p function file-name))
 600                   (if (commandp def)
 601                       "an interactive autoloaded "
 602                     "an autoloaded ")
 603                 (if (commandp def) "an interactive " "a "))))
 604
 605     ;; Print what kind of function-like object FUNCTION is.
 606     (princ (cond ((or (stringp def) (vectorp def))
 607                   "a keyboard macro")
 608                  ;; Aliases are Lisp functions, so we need to check
 609                  ;; aliases before functions.
 610                  (aliased
 611                   (format-message "an alias for `%s'" real-def))
 612                  ((subrp def)
 613                   (if (eq 'unevalled (cdr (subr-arity def)))
 614                       (concat beg "special form")
 615                     (concat beg "built-in function")))
 616                  ((autoloadp def)
 617                   (format "%s autoloaded %s"
 618                           (if (commandp def) "an interactive" "an")
 619                           (if (eq (nth 4 def) 'keymap) "keymap"
 620                             (if (nth 4 def) "Lisp macro" "Lisp function"))))
 621                  ((or (eq (car-safe def) 'macro)
 622                       ;; For advised macros, def is a lambda
 623                       ;; expression or a byte-code-function-p, so we
 624                       ;; need to check macros before functions.
 625                       (macrop function))
 626                   (concat beg "Lisp macro"))
 627                  ((byte-code-function-p def)
 628                   (concat beg "compiled Lisp function"))
 629                  ((eq (car-safe def) 'lambda)
 630                   (concat beg "Lisp function"))
 631                  ((eq (car-safe def) 'closure)
 632                   (concat beg "Lisp closure"))
 633                  ((keymapp def)
 634                   (let ((is-full nil)
 635                         (elts (cdr-safe def)))
 636                     (while elts
 637                       (if (char-table-p (car-safe elts))
 638                           (setq is-full t
 639                                 elts nil))
 640                       (setq elts (cdr-safe elts)))
 641                     (concat beg (if is-full "keymap" "sparse keymap"))))
 642                  (t "")))
 643
 644     (if (and aliased (not (fboundp real-def)))
 645         (princ ",\nwhich is not defined.  Please make a bug report.")
 646       (with-current-buffer standard-output
 647         (save-excursion
 648           (save-match-data
 649             (when (re-search-backward (substitute-command-keys
 650                                        "alias for `\\([^`']+\\)'")
 651                                       nil t)
 652               (help-xref-button 1 'help-function real-def)))))
 653
 654       (when file-name
 655         ;; We used to add .el to the file name,
 656         ;; but that's completely wrong when the user used load-file.
 657         (princ (format-message " in `%s'"
 658                                (if (eq file-name 'C-source)
 659                                    "C source code"
 660                                  (help-fns-short-filename file-name))))
 661         ;; Make a hyperlink to the library.
 662         (with-current-buffer standard-output
 663           (save-excursion
 664             (re-search-backward (substitute-command-keys "`\\([^`']+\\)'")
 665                                 nil t)
 666             (help-xref-button 1 'help-function-def function file-name))))
 667       (princ ".")
 668       (with-current-buffer (help-buffer)
 669         (fill-region-as-paragraph (save-excursion (goto-char pt1) (forward-line 0) (point))
 670                                   (point)))
 671       (terpri)(terpri)
 672
 673       (let ((doc-raw (documentation function t))
 674             (key-bindings-buffer (current-buffer)))
 675
 676         ;; If the function is autoloaded, and its docstring has
 677         ;; key substitution constructs, load the library.
 678         (and (autoloadp real-def) doc-raw
 679              help-enable-auto-load
 680              (string-match "\\([^\\]=\\|[^=]\\|\\`\\)\\\\[[{<]" doc-raw)
 681              (autoload-do-load real-def))
 682
 683         (help-fns--key-bindings function)
 684         (with-current-buffer standard-output
 685           (let ((doc (help-fns--signature function doc-raw sig-key
 686                                           real-function key-bindings-buffer)))
 687             (run-hook-with-args 'help-fns-describe-function-functions function)
 688             (insert "\n"
 689                     (or doc "Not documented."))
 690             ;; Avoid asking the user annoying questions if she decides
 691             ;; to save the help buffer, when her locale's codeset
 692             ;; isn't UTF-8.
 693             (unless (memq text-quoting-style '(straight grave))
 694               (set-buffer-file-coding-system 'utf-8))))))))
 695
 696 ;; Add defaults to `help-fns-describe-function-functions'.
 697 (add-hook 'help-fns-describe-function-functions #'help-fns--obsolete)
 698 (add-hook 'help-fns-describe-function-functions #'help-fns--interactive-only)
 699 (add-hook 'help-fns-describe-function-functions #'help-fns--parent-mode)
 700 (add-hook 'help-fns-describe-function-functions #'help-fns--compiler-macro)
 701
 702 \f
 703 ;; Variables
 704
 705 ;;;###autoload
 706 (defun variable-at-point (&optional any-symbol)
 707   "Return the bound variable symbol found at or before point.
 708 Return 0 if there is no such symbol.
 709 If ANY-SYMBOL is non-nil, don't insist the symbol be bound."
 710   (with-syntax-table emacs-lisp-mode-syntax-table
 711     (or (condition-case ()
 712             (save-excursion
 713               (skip-chars-forward "'")
 714               (or (not (zerop (skip-syntax-backward "_w")))
 715                   (eq (char-syntax (following-char)) ?w)
 716                   (eq (char-syntax (following-char)) ?_)
 717                   (forward-sexp -1))
 718               (skip-chars-forward "'")
 719               (let ((obj (read (current-buffer))))
 720                 (and (symbolp obj) (boundp obj) obj)))
 721           (error nil))
 722         (let* ((str (find-tag-default))
 723                (sym (if str (intern-soft str))))
 724           (if (and sym (or any-symbol (boundp sym)))
 725               sym
 726             (save-match-data
 727               (when (and str (string-match "\\`\\W*\\(.*?\\)\\W*\\'" str))
 728                 (setq sym (intern-soft (match-string 1 str)))
 729                 (and (or any-symbol (boundp sym)) sym)))))
 730         0)))
 731
 732 (defun describe-variable-custom-version-info (variable)
 733   (let ((custom-version (get variable 'custom-version))
 734         (cpv (get variable 'custom-package-version))
 735         (output nil))
 736     (if custom-version
 737         (setq output
 738               (format "This variable was introduced, or its default value was changed, in\nversion %s of Emacs.\n"
 739                       custom-version))
 740       (when cpv
 741         (let* ((package (car-safe cpv))
 742                (version (if (listp (cdr-safe cpv))
 743                             (car (cdr-safe cpv))
 744                           (cdr-safe cpv)))
 745                (pkg-versions (assq package customize-package-emacs-version-alist))
 746                (emacsv (cdr (assoc version pkg-versions))))
 747           (if (and package version)
 748               (setq output
 749                     (format (concat "This variable was introduced, or its default value was changed, in\nversion %s of the %s package"
 750                                     (if emacsv
 751                                         (format " that is part of Emacs %s" emacsv))
 752                                     ".\n")
 753                             version package))))))
 754     output))
 755
 756 ;;;###autoload
 757 (defun describe-variable (variable &optional buffer frame)
 758   "Display the full documentation of VARIABLE (a symbol).
 759 Returns the documentation as a string, also.
 760 If VARIABLE has a buffer-local value in BUFFER or FRAME
 761 \(default to the current buffer and current frame),
 762 it is displayed along with the global value."
 763   (interactive
 764    (let ((v (variable-at-point))
 765          (enable-recursive-minibuffers t)
 766          (orig-buffer (current-buffer))
 767          val)
 768      (setq val (completing-read
 769                 (if (symbolp v)
 770                     (format
 771                      "Describe variable (default %s): " v)
 772                   "Describe variable: ")
 773                 #'help--symbol-completion-table
 774                 (lambda (vv)
 775                   ;; In case the variable only exists in the buffer
 776                   ;; the command we switch back to that buffer before
 777                   ;; we examine the variable.
 778                   (with-current-buffer orig-buffer
 779                     (or (get vv 'variable-documentation)
 780                         (and (boundp vv) (not (keywordp vv))))))
 781                 t nil nil
 782                 (if (symbolp v) (symbol-name v))))
 783      (list (if (equal val "")
 784                v (intern val)))))
 785   (let (file-name)
 786     (unless (buffer-live-p buffer) (setq buffer (current-buffer)))
 787     (unless (frame-live-p frame) (setq frame (selected-frame)))
 788     (if (not (symbolp variable))
 789         (message "You did not specify a variable")
 790       (save-excursion
 791         (let ((valvoid (not (with-current-buffer buffer (boundp variable))))
 792               (permanent-local (get variable 'permanent-local))
 793               val val-start-pos locus)
 794           ;; Extract the value before setting up the output buffer,
 795           ;; in case `buffer' *is* the output buffer.
 796           (unless valvoid
 797             (with-selected-frame frame
 798               (with-current-buffer buffer
 799                 (setq val (symbol-value variable)
 800                       locus (variable-binding-locus variable)))))
 801           (help-setup-xref (list #'describe-variable variable buffer)
 802                            (called-interactively-p 'interactive))
 803           (with-help-window (help-buffer)
 804             (with-current-buffer buffer
 805               (prin1 variable)
 806               (setq file-name (find-lisp-object-file-name variable 'defvar))
 807
 808               (if file-name
 809                   (progn
 810                     (princ (format-message
 811                             " is a variable defined in `%s'.\n"
 812                             (if (eq file-name 'C-source)
 813                                 "C source code"
 814                               (file-name-nondirectory file-name))))
 815                     (with-current-buffer standard-output
 816                       (save-excursion
 817                         (re-search-backward (substitute-command-keys
 818                                              "`\\([^`']+\\)'")
 819                                             nil t)
 820                         (help-xref-button 1 'help-variable-def
 821                                           variable file-name)))
 822                     (if valvoid
 823                         (princ "It is void as a variable.")
 824                       (princ "Its ")))
 825                 (if valvoid
 826                     (princ " is void as a variable.")
 827                   (princ (substitute-command-keys "'s ")))))
 828             (unless valvoid
 829               (with-current-buffer standard-output
 830                 (setq val-start-pos (point))
 831                 (princ "value is")
 832                 (let ((line-beg (line-beginning-position))
 833                       (print-rep
 834                        (let ((rep
 835                               (let ((print-quoted t))
 836                                 (prin1-to-string val))))
 837                          (if (and (symbolp val) (not (booleanp val)))
 838                              (format-message "`%s'" rep)
 839                            rep))))
 840                   (if (< (+ (length print-rep) (point) (- line-beg)) 68)
 841                       (insert " " print-rep)
 842                     (terpri)
 843                     (pp val)
 844                     ;; Remove trailing newline.
 845                     (delete-char -1))
 846                   (let* ((sv (get variable 'standard-value))
 847                          (origval (and (consp sv)
 848                                        (condition-case nil
 849                                            (eval (car sv))
 850                                          (error :help-eval-error))))
 851                          from)
 852                     (when (and (consp sv)
 853                                (not (equal origval val))
 854                                (not (equal origval :help-eval-error)))
 855                       (princ "\nOriginal value was \n")
 856                       (setq from (point))
 857                       (pp origval)
 858                       (if (< (point) (+ from 20))
 859                           (delete-region (1- from) from)))))))
 860             (terpri)
 861             (when locus
 862               (cond
 863                ((bufferp locus)
 864                 (princ (format "Local in buffer %s; "
 865                                (buffer-name buffer))))
 866                ((framep locus)
 867                 (princ (format "It is a frame-local variable; ")))
 868                ((terminal-live-p locus)
 869                 (princ (format "It is a terminal-local variable; ")))
 870                (t
 871                 (princ (format "It is local to %S" locus))))
 872               (if (not (default-boundp variable))
 873                   (princ "globally void")
 874                 (let ((global-val (default-value variable)))
 875                   (with-current-buffer standard-output
 876                     (princ "global value is ")
 877                     (if (eq val global-val)
 878                         (princ "the same.")
 879                       (terpri)
 880                       ;; Fixme: pp can take an age if you happen to
 881                       ;; ask for a very large expression.  We should
 882                       ;; probably print it raw once and check it's a
 883                       ;; sensible size before prettyprinting.  -- fx
 884                       (let ((from (point)))
 885                         (pp global-val)
 886                         ;; See previous comment for this function.
 887                         ;; (help-xref-on-pp from (point))
 888                         (if (< (point) (+ from 20))
 889                             (delete-region (1- from) from)))))))
 890               (terpri))
 891
 892             ;; If the value is large, move it to the end.
 893             (with-current-buffer standard-output
 894               (when (> (count-lines (point-min) (point-max)) 10)
 895                 ;; Note that setting the syntax table like below
 896                 ;; makes forward-sexp move over a `'s' at the end
 897                 ;; of a symbol.
 898                 (set-syntax-table emacs-lisp-mode-syntax-table)
 899                 (goto-char val-start-pos)
 900                 ;; The line below previously read as
 901                 ;; (delete-region (point) (progn (end-of-line) (point)))
 902                 ;; which suppressed display of the buffer local value for
 903                 ;; large values.
 904                 (when (looking-at "value is") (replace-match ""))
 905                 (save-excursion
 906                   (insert "\n\nValue:")
 907                   (set (make-local-variable 'help-button-cache)
 908                        (point-marker)))
 909                 (insert "value is shown ")
 910                 (insert-button "below"
 911                                'action help-button-cache
 912                                'follow-link t
 913                                'help-echo "mouse-2, RET: show value")
 914                 (insert ".\n")))
 915             (terpri)
 916
 917             (let* ((alias (condition-case nil
 918                               (indirect-variable variable)
 919                             (error variable)))
 920                    (obsolete (get variable 'byte-obsolete-variable))
 921                    (watchpoints (get-variable-watchers variable))
 922                    (use (car obsolete))
 923                    (safe-var (get variable 'safe-local-variable))
 924                    (doc (or (documentation-property
 925                              variable 'variable-documentation)
 926                             (documentation-property
 927                              alias 'variable-documentation)))
 928                    (extra-line nil))
 929
 930               ;; Mention if it's a local variable.
 931               (cond
 932                ((and (local-variable-if-set-p variable)
 933                      (or (not (local-variable-p variable))
 934                          (with-temp-buffer
 935                            (local-variable-if-set-p variable))))
 936                 (setq extra-line t)
 937                 (princ "  Automatically becomes ")
 938                 (if permanent-local
 939                     (princ "permanently "))
 940                 (princ "buffer-local when set.\n"))
 941                ((not permanent-local))
 942                ((bufferp locus)
 943                 (setq extra-line t)
 944                 (princ
 945                  (substitute-command-keys
 946                   "  This variable's buffer-local value is permanent.\n")))
 947                (t
 948                 (setq extra-line t)
 949                 (princ (substitute-command-keys
 950                         "  This variable's value is permanent \
 951 if it is given a local binding.\n"))))
 952
 953               ;; Mention if it's an alias.
 954               (unless (eq alias variable)
 955                 (setq extra-line t)
 956                 (princ (format-message
 957                         "  This variable is an alias for `%s'.\n"
 958                         alias)))
 959
 960               (when obsolete
 961                 (setq extra-line t)
 962                 (princ "  This variable is obsolete")
 963                 (if (nth 2 obsolete)
 964                     (princ (format " since %s" (nth 2 obsolete))))
 965                 (princ (cond ((stringp use) (concat ";\n  " use))
 966                              (use (format-message ";\n  use `%s' instead."
 967                                                   (car obsolete)))
 968                              (t ".")))
 969                 (terpri))
 970
 971               (when watchpoints
 972                 (setq extra-line t)
 973                 (princ "  Calls these functions when changed: ")
 974                 (princ watchpoints)
 975                 (terpri))
 976
 977               (when (member (cons variable val)
 978                             (with-current-buffer buffer
 979                               file-local-variables-alist))
 980                 (setq extra-line t)
 981                 (if (member (cons variable val)
 982                              (with-current-buffer buffer
 983                                dir-local-variables-alist))
 984                     (let ((file (and (buffer-file-name buffer)
 985                                       (not (file-remote-p
 986                                             (buffer-file-name buffer)))
 987                                       (dir-locals-find-file
 988                                        (buffer-file-name buffer))))
 989                           (is-directory nil))
 990                       (princ (substitute-command-keys
 991                               "  This variable's value is directory-local"))
 992                       (when (consp file) ; result from cache
 993                         ;; If the cache element has an mtime, we
 994                         ;; assume it came from a file.
 995                         (if (nth 2 file)
 996                             ;; (car file) is a directory.
 997                             (setq file (dir-locals--all-files (car file)))
 998                           ;; Otherwise, assume it was set directly.
 999                           (setq file (car file)
1000                                 is-directory t)))
1001                       (if (null file)
1002                           (princ ".\n")
1003                         (princ ", set ")
1004                         (princ (substitute-command-keys
1005                                 (cond
1006                                  (is-directory "for the directory\n  `")
1007                                  ;; Many files matched.
1008                                  ((and (consp file) (cdr file))
1009                                   (setq file (file-name-directory (car file)))
1010                                   (format "by one of the\n  %s files in the directory\n  `"
1011                                           dir-locals-file))
1012                                  (t (setq file (car file))
1013                                     "by the file\n  `"))))
1014                         (with-current-buffer standard-output
1015                           (insert-text-button
1016                            file 'type 'help-dir-local-var-def
1017                              'help-args (list variable file)))
1018                         (princ (substitute-command-keys "'.\n"))))
1019                   (princ (substitute-command-keys
1020                           "  This variable's value is file-local.\n"))))
1021
1022               (when (memq variable ignored-local-variables)
1023                 (setq extra-line t)
1024                 (princ "  This variable is ignored as a file-local \
1025 variable.\n"))
1026
1027               ;; Can be both risky and safe, eg auto-fill-function.
1028               (when (risky-local-variable-p variable)
1029                 (setq extra-line t)
1030                 (princ "  This variable may be risky if used as a \
1031 file-local variable.\n")
1032                 (when (assq variable safe-local-variable-values)
1033                   (princ (substitute-command-keys
1034                           "  However, you have added it to \
1035 `safe-local-variable-values'.\n"))))
1036
1037               (when safe-var
1038                 (setq extra-line t)
1039                 (princ "  This variable is safe as a file local variable ")
1040                 (princ "if its value\n  satisfies the predicate ")
1041                 (princ (if (byte-code-function-p safe-var)
1042                            "which is a byte-compiled expression.\n"
1043                          (format-message "`%s'.\n" safe-var))))
1044
1045               (if extra-line (terpri))
1046               (princ "Documentation:\n")
1047               (with-current-buffer standard-output
1048                 (insert (or doc "Not documented as a variable."))))
1049
1050             ;; Make a link to customize if this variable can be customized.
1051             (when (custom-variable-p variable)
1052               (let ((customize-label "customize"))
1053                 (terpri)
1054                 (terpri)
1055                 (princ (concat "You can " customize-label " this variable."))
1056                 (with-current-buffer standard-output
1057                   (save-excursion
1058                     (re-search-backward
1059                      (concat "\\(" customize-label "\\)") nil t)
1060                     (help-xref-button 1 'help-customize-variable variable))))
1061               ;; Note variable's version or package version.
1062               (let ((output (describe-variable-custom-version-info variable)))
1063                 (when output
1064                   (terpri)
1065                   (terpri)
1066                   (princ output))))
1067
1068             (with-current-buffer standard-output
1069               ;; Return the text we displayed.
1070               (buffer-string))))))))
1071
1072
1073 (defvar help-xref-stack-item)
1074
1075 ;;;###autoload
1076 (defun describe-symbol (symbol &optional buffer frame)
1077   "Display the full documentation of SYMBOL.
1078 Will show the info of SYMBOL as a function, variable, and/or face.
1079 Optional arguments BUFFER and FRAME specify for which buffer and
1080 frame to show the information about SYMBOL; they default to the
1081 current buffer and the selected frame, respectively."
1082   (interactive
1083    (let* ((v-or-f (symbol-at-point))
1084           (found (cl-some (lambda (x) (funcall (nth 1 x) v-or-f))
1085                           describe-symbol-backends))
1086           (v-or-f (if found v-or-f (function-called-at-point)))
1087           (found (or found v-or-f))
1088           (enable-recursive-minibuffers t)
1089           (val (completing-read (if found
1090                                     (format
1091                                      "Describe symbol (default %s): " v-or-f)
1092                                   "Describe symbol: ")
1093                                 obarray
1094                                 (lambda (vv)
1095                                   (cl-some (lambda (x) (funcall (nth 1 x) vv))
1096                                            describe-symbol-backends))
1097                                 t nil nil
1098                                 (if found (symbol-name v-or-f)))))
1099      (list (if (equal val "")
1100                v-or-f (intern val)))))
1101   (if (not (symbolp symbol))
1102       (user-error "You didn't specify a function or variable"))
1103   (unless (buffer-live-p buffer) (setq buffer (current-buffer)))
1104   (unless (frame-live-p frame) (setq frame (selected-frame)))
1105   (with-current-buffer (help-buffer)
1106     ;; Push the previous item on the stack before clobbering the output buffer.
1107     (help-setup-xref nil nil)
1108     (let* ((docs
1109             (nreverse
1110              (delq nil
1111                    (mapcar (pcase-lambda (`(,name ,testfn ,descfn))
1112                              (when (funcall testfn symbol)
1113                                ;; Don't record the current entry in the stack.
1114                                (setq help-xref-stack-item nil)
1115                                (cons name
1116                                      (funcall descfn symbol buffer frame))))
1117                            describe-symbol-backends))))
1118            (single (null (cdr docs))))
1119       (while (cdr docs)
1120         (goto-char (point-min))
1121         (let ((inhibit-read-only t)
1122               (name (caar docs))        ;Name of doc currently at BOB.
1123               (doc (cdr (cadr docs))))  ;Doc to add at BOB.
1124           (when doc
1125             (insert doc)
1126             (delete-region (point)
1127                            (progn (skip-chars-backward " \t\n") (point)))
1128             (insert "\n\n"
1129                     (eval-when-compile
1130                       (propertize "\n" 'face '(:height 0.1 :inverse-video t)))
1131                     "\n")
1132             (when name
1133               (insert (symbol-name symbol)
1134                       " is also a " name "." "\n\n"))))
1135         (setq docs (cdr docs)))
1136       (unless single
1137         ;; Don't record the `describe-variable' item in the stack.
1138         (setq help-xref-stack-item nil)
1139         (help-setup-xref (list #'describe-symbol symbol) nil))
1140       (goto-char (point-min)))))
1141
1142 ;;;###autoload
1143 (defun describe-syntax (&optional buffer)
1144   "Describe the syntax specifications in the syntax table of BUFFER.
1145 The descriptions are inserted in a help buffer, which is then displayed.
1146 BUFFER defaults to the current buffer."
1147   (interactive)
1148   (setq buffer (or buffer (current-buffer)))
1149   (help-setup-xref (list #'describe-syntax buffer)
1150                    (called-interactively-p 'interactive))
1151   (with-help-window (help-buffer)
1152     (let ((table (with-current-buffer buffer (syntax-table))))
1153       (with-current-buffer standard-output
1154         (describe-vector table 'internal-describe-syntax-value)
1155         (while (setq table (char-table-parent table))
1156           (insert "\nThe parent syntax table is:")
1157           (describe-vector table 'internal-describe-syntax-value))))))
1158
1159 (defun help-describe-category-set (value)
1160   (insert (cond
1161            ((null value) "default")
1162            ((char-table-p value) "deeper char-table ...")
1163            (t (condition-case nil
1164                   (category-set-mnemonics value)
1165                 (error "invalid"))))))
1166
1167 ;;;###autoload
1168 (defun describe-categories (&optional buffer)
1169   "Describe the category specifications in the current category table.
1170 The descriptions are inserted in a buffer, which is then displayed.
1171 If BUFFER is non-nil, then describe BUFFER's category table instead.
1172 BUFFER should be a buffer or a buffer name."
1173   (interactive)
1174   (setq buffer (or buffer (current-buffer)))
1175   (help-setup-xref (list #'describe-categories buffer)
1176                    (called-interactively-p 'interactive))
1177   (with-help-window (help-buffer)
1178     (let* ((table (with-current-buffer buffer (category-table)))
1179            (docs (char-table-extra-slot table 0)))
1180       (if (or (not (vectorp docs)) (/= (length docs) 95))
1181           (error "Invalid first extra slot in this category table\n"))
1182       (with-current-buffer standard-output
1183         (setq-default help-button-cache (make-marker))
1184         (insert "Legend of category mnemonics ")
1185         (insert-button "(longer descriptions at the bottom)"
1186                        'action help-button-cache
1187                        'follow-link t
1188                        'help-echo "mouse-2, RET: show full legend")
1189         (insert "\n")
1190         (let ((pos (point)) (items 0) lines n)
1191           (dotimes (i 95)
1192             (if (aref docs i) (setq items (1+ items))))
1193           (setq lines (1+ (/ (1- items) 4)))
1194           (setq n 0)
1195           (dotimes (i 95)
1196             (let ((elt (aref docs i)))
1197               (when elt
1198                 (string-match ".*" elt)
1199                 (setq elt (match-string 0 elt))
1200                 (if (>= (length elt) 17)
1201                     (setq elt (concat (substring elt 0 14) "...")))
1202                 (if (< (point) (point-max))
1203                     (move-to-column (* 20 (/ n lines)) t))
1204                 (insert (+ i ?\s) ?: elt)
1205                 (if (< (point) (point-max))
1206                     (forward-line 1)
1207                   (insert "\n"))
1208                 (setq n (1+ n))
1209                 (if (= (% n lines) 0)
1210                     (goto-char pos))))))
1211         (goto-char (point-max))
1212         (insert "\n"
1213                 "character(s)\tcategory mnemonics\n"
1214                 "------------\t------------------")
1215         (describe-vector table 'help-describe-category-set)
1216         (set-marker help-button-cache (point))
1217         (insert "Legend of category mnemonics:\n")
1218         (dotimes (i 95)
1219           (let ((elt (aref docs i)))
1220             (when elt
1221               (if (string-match "\n" elt)
1222                   (setq elt (substring elt (match-end 0))))
1223               (insert (+ i ?\s) ": " elt "\n"))))
1224         (while (setq table (char-table-parent table))
1225           (insert "\nThe parent category table is:")
1226           (describe-vector table 'help-describe-category-set))))))
1227
1228 \f
1229 ;;; Replacements for old lib-src/ programs.  Don't seem especially useful.
1230
1231 ;; Replaces lib-src/digest-doc.c.
1232 ;;;###autoload
1233 (defun doc-file-to-man (file)
1234   "Produce an nroff buffer containing the doc-strings from the DOC file."
1235   (interactive (list (read-file-name "Name of DOC file: " doc-directory
1236                                      internal-doc-file-name t)))
1237   (or (file-readable-p file)
1238       (error "Cannot read file `%s'" file))
1239   (pop-to-buffer (generate-new-buffer "*man-doc*"))
1240   (setq buffer-undo-list t)
1241   (insert ".TH \"Command Summary for GNU Emacs\"\n"
1242           ".AU Richard M. Stallman\n")
1243   (insert-file-contents file)
1244   (let (notfirst)
1245     (while (search-forward "\x1f" nil 'move)
1246       (if (looking-at "S")
1247           (delete-region (1- (point)) (line-end-position))
1248         (delete-char -1)
1249         (if notfirst
1250             (insert "\n.DE\n")
1251           (setq notfirst t))
1252         (insert "\n.SH ")
1253         (insert (if (looking-at "F") "Function " "Variable "))
1254         (delete-char 1)
1255         (forward-line 1)
1256         (insert ".DS L\n"))))
1257   (insert "\n.DE\n")
1258   (setq buffer-undo-list nil)
1259   (nroff-mode))
1260
1261 ;; Replaces lib-src/sorted-doc.c.
1262 ;;;###autoload
1263 (defun doc-file-to-info (file)
1264   "Produce a texinfo buffer with sorted doc-strings from the DOC file."
1265   (interactive (list (read-file-name "Name of DOC file: " doc-directory
1266                                      internal-doc-file-name t)))
1267   (or (file-readable-p file)
1268       (error "Cannot read file `%s'" file))
1269   (let ((i 0) type name doc alist)
1270     (with-temp-buffer
1271       (insert-file-contents file)
1272       ;; The characters "@{}" need special treatment.
1273       (while (re-search-forward "[@{}]" nil t)
1274         (backward-char)
1275         (insert "@")
1276         (forward-char 1))
1277       (goto-char (point-min))
1278       (while (search-forward "\x1f" nil t)
1279         (unless (looking-at "S")
1280           (setq type (char-after)
1281                 name (buffer-substring (1+ (point)) (line-end-position))
1282                 doc (buffer-substring (line-beginning-position 2)
1283                                       (if (search-forward  "\x1f" nil 'move)
1284                                           (1- (point))
1285                                         (point)))
1286                 alist (cons (list name type doc) alist))
1287           (backward-char 1))))
1288     (pop-to-buffer (generate-new-buffer "*info-doc*"))
1289     (setq buffer-undo-list t)
1290     ;; Write the output header.
1291     (insert "\\input texinfo  @c -*-texinfo-*-\n"
1292             "@setfilename emacsdoc.info\n"
1293             "@settitle Command Summary for GNU Emacs\n"
1294             "@finalout\n"
1295             "\n@node Top\n"
1296             "@unnumbered Command Summary for GNU Emacs\n\n"
1297             "@table @asis\n\n"
1298             "@iftex\n"
1299             "@global@let@ITEM@item\n"
1300             "@def@item{@filbreak@vskip5pt@ITEM}\n"
1301             "@font@tensy cmsy10 scaled @magstephalf\n"
1302             "@font@teni cmmi10 scaled @magstephalf\n"
1303             "@def\\{{@tensy@char110}}\n" ; this backslash goes with cmr10
1304             "@def|{{@tensy@char106}}\n"
1305             "@def@{{{@tensy@char102}}\n"
1306             "@def@}{{@tensy@char103}}\n"
1307             "@def<{{@teni@char62}}\n"
1308             "@def>{{@teni@char60}}\n"
1309             "@chardef@@64\n"
1310             "@catcode43=12\n"
1311             "@tableindent-0.2in\n"
1312             "@end iftex\n")
1313     ;; Sort the array by name; within each name, by type (functions first).
1314     (setq alist (sort alist (lambda (e1 e2)
1315                               (if (string-equal (car e1) (car e2))
1316                                   (<= (cadr e1) (cadr e2))
1317                                 (string-lessp (car e1) (car e2))))))
1318     ;; Print each function.
1319     (dolist (e alist)
1320       (insert "\n@item "
1321               (if (char-equal (cadr e) ?\F) "Function" "Variable")
1322               " @code{" (car e) "}\n@display\n"
1323               (nth 2 e)
1324               "\n@end display\n")
1325       ;; Try to avoid a save size overflow in the TeX output routine.
1326       (if (zerop (setq i (% (1+ i) 100)))
1327           (insert "\n@end table\n@table @asis\n")))
1328     (insert "@end table\n"
1329             "@bye\n")
1330     (setq buffer-undo-list nil)
1331     (texinfo-mode)))
1332
1333 (provide 'help-fns)
1334
1335 ;;; help-fns.el ends here