lisp/help-fns.el

   1 ;;; help-fns.el --- Complex help functions
   2
   3 ;; Copyright (C) 1985-1986, 1993-1994, 1998-2011
   4 ;;   Free Software Foundation, Inc.
   5
   6 ;; Maintainer: FSF
   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 ;; Functions
  36
  37 ;;;###autoload
  38 (defun describe-function (function)
  39   "Display the full documentation of FUNCTION (a symbol)."
  40   (interactive
  41    (let ((fn (function-called-at-point))
  42          (enable-recursive-minibuffers t)
  43          val)
  44      (setq val (completing-read (if fn
  45                                     (format "Describe function (default %s): " fn)
  46                                   "Describe function: ")
  47                                 obarray 'fboundp t nil nil
  48                                 (and fn (symbol-name fn))))
  49      (list (if (equal val "")
  50                fn (intern val)))))
  51   (if (null function)
  52       (message "You didn't specify a function")
  53     (help-setup-xref (list #'describe-function function)
  54                      (called-interactively-p 'interactive))
  55     (save-excursion
  56       (with-help-window (help-buffer)
  57         (prin1 function)
  58         ;; Use " is " instead of a colon so that
  59         ;; it is easier to get out the function name using forward-sexp.
  60         (princ " is ")
  61         (describe-function-1 function)
  62         (with-current-buffer standard-output
  63           ;; Return the text we displayed.
  64           (buffer-string))))))
  65
  66 (defun help-split-fundoc (docstring def)
  67   "Split a function DOCSTRING into the actual doc and the usage info.
  68 Return (USAGE . DOC) or nil if there's no usage info.
  69 DEF is the function whose usage we're looking for in DOCSTRING."
  70   ;; Functions can get the calling sequence at the end of the doc string.
  71   ;; In cases where `function' has been fset to a subr we can't search for
  72   ;; function's name in the doc string so we use `fn' as the anonymous
  73   ;; function name instead.
  74   (when (and docstring (string-match "\n\n(fn\\(\\( .*\\)?)\\)\\'" docstring))
  75     (cons (format "(%s%s"
  76                   ;; Replace `fn' with the actual function name.
  77                   (if (consp def) "anonymous" def)
  78                   (match-string 1 docstring))
  79           (unless (zerop (match-beginning 0))
  80             (substring docstring 0 (match-beginning 0))))))
  81
  82 ;; FIXME: Move to subr.el?
  83 (defun help-add-fundoc-usage (docstring arglist)
  84   "Add the usage info to DOCSTRING.
  85 If DOCSTRING already has a usage info, then just return it unchanged.
  86 The usage info is built from ARGLIST.  DOCSTRING can be nil.
  87 ARGLIST can also be t or a string of the form \"(FUN ARG1 ARG2 ...)\"."
  88   (unless (stringp docstring) (setq docstring ""))
  89   (if (or (string-match "\n\n(fn\\(\\( .*\\)?)\\)\\'" docstring)
  90           (eq arglist t))
  91       docstring
  92     (concat docstring
  93             (if (string-match "\n?\n\\'" docstring)
  94                 (if (< (- (match-end 0) (match-beginning 0)) 2) "\n" "")
  95               "\n\n")
  96             (if (and (stringp arglist)
  97                      (string-match "\\`([^ ]+\\(.*\\))\\'" arglist))
  98                 (concat "(fn" (match-string 1 arglist) ")")
  99               (format "%S" (help-make-usage 'fn arglist))))))
 100
 101 ;; FIXME: Move to subr.el?
 102 (defun help-function-arglist (def)
 103   ;; Handle symbols aliased to other symbols.
 104   (if (and (symbolp def) (fboundp def)) (setq def (indirect-function def)))
 105   ;; If definition is a macro, find the function inside it.
 106   (if (eq (car-safe def) 'macro) (setq def (cdr def)))
 107   (cond
 108    ((and (byte-code-function-p def) (integerp (aref def 0)))
 109     (let* ((args-desc (aref def 0))
 110            (max (lsh args-desc -8))
 111            (min (logand args-desc 127))
 112            (rest (logand args-desc 128))
 113            (arglist ()))
 114       (dotimes (i min)
 115         (push (intern (concat "arg" (number-to-string (1+ i)))) arglist))
 116       (when (> max min)
 117         (push '&optional arglist)
 118         (dotimes (i (- max min))
 119           (push (intern (concat "arg" (number-to-string (+ 1 i min))))
 120                 arglist)))
 121       (unless (zerop rest) (push '&rest arglist) (push 'rest arglist))
 122       (nreverse arglist)))
 123    ((byte-code-function-p def) (aref def 0))
 124    ((eq (car-safe def) 'lambda) (nth 1 def))
 125    ((eq (car-safe def) 'closure) (nth 2 def))
 126    ((subrp def)
 127     (let ((arity (subr-arity def))
 128           (arglist ()))
 129       (dotimes (i (car arity))
 130         (push (intern (concat "arg" (number-to-string (1+ i)))) arglist))
 131       (cond
 132        ((not (numberp (cdr arglist)))
 133         (push '&rest arglist)
 134         (push 'rest arglist))
 135        ((< (car arity) (cdr arity))
 136         (push '&optional arglist)
 137         (dotimes (i (- (cdr arity) (car arity)))
 138           (push (intern (concat "arg" (number-to-string
 139                                        (+ 1 i (car arity)))))
 140                 arglist))))
 141       (nreverse arglist)))
 142    ((and (eq (car-safe def) 'autoload) (not (eq (nth 4 def) 'keymap)))
 143     "[Arg list not available until function definition is loaded.]")
 144    (t t)))
 145
 146 ;; FIXME: Move to subr.el?
 147 (defun help-make-usage (function arglist)
 148   (cons (if (symbolp function) function 'anonymous)
 149         (mapcar (lambda (arg)
 150                   (if (not (symbolp arg))
 151                       (if (and (consp arg) (symbolp (car arg)))
 152                           ;; CL style default values for optional args.
 153                           (cons (intern (upcase (symbol-name (car arg))))
 154                                 (cdr arg))
 155                         arg)
 156                     (let ((name (symbol-name arg)))
 157                       (cond
 158                        ((string-match "\\`&" name) arg)
 159                        ((string-match "\\`_" name)
 160                         (intern (upcase (substring name 1))))
 161                        (t (intern (upcase name)))))))
 162                 arglist)))
 163
 164 ;; Could be this, if we make symbol-file do the work below.
 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 ;;   (symbol-file (if (symbolp subr-or-var) subr-or-var
 169 ;;               (subr-name subr-or-var))
 170 ;;             (if (eq kind 'var) 'defvar 'defun)))
 171 ;;;###autoload
 172 (defun help-C-file-name (subr-or-var kind)
 173   "Return the name of the C file where SUBR-OR-VAR is defined.
 174 KIND should be `var' for a variable or `subr' for a subroutine."
 175   (let ((docbuf (get-buffer-create " *DOC*"))
 176         (name (if (eq 'var kind)
 177                   (concat "V" (symbol-name subr-or-var))
 178                 (concat "F" (subr-name subr-or-var)))))
 179     (with-current-buffer docbuf
 180       (goto-char (point-min))
 181       (if (eobp)
 182           (insert-file-contents-literally
 183            (expand-file-name internal-doc-file-name doc-directory)))
 184       (let ((file (catch 'loop
 185                     (while t
 186                       (let ((pnt (search-forward (concat "\1f" name "\n"))))
 187                         (re-search-backward "\1fS\\(.*\\)")
 188                         (let ((file (match-string 1)))
 189                           (if (member file build-files)
 190                               (throw 'loop file)
 191                             (goto-char pnt))))))))
 192         (if (string-match "^ns.*\\(\\.o\\|obj\\)\\'" file)
 193             (setq file (replace-match ".m" t t file 1))
 194           (if (string-match "\\.\\(o\\|obj\\)\\'" file)
 195               (setq file (replace-match ".c" t t file))))
 196         (if (string-match "\\.\\(c\\|m\\)\\'" file)
 197             (concat "src/" file)
 198           file)))))
 199
 200 (defcustom help-downcase-arguments nil
 201   "If non-nil, argument names in *Help* buffers are downcased."
 202   :type 'boolean
 203   :group 'help
 204   :version "23.2")
 205
 206 (defun help-highlight-arg (arg)
 207   "Highlight ARG as an argument name for a *Help* buffer.
 208 Return ARG in face `help-argument-name'; ARG is also downcased
 209 if the variable `help-downcase-arguments' is non-nil."
 210   (propertize (if help-downcase-arguments (downcase arg) arg)
 211               'face 'help-argument-name))
 212
 213 (defun help-do-arg-highlight (doc args)
 214   (with-syntax-table (make-syntax-table emacs-lisp-mode-syntax-table)
 215     (modify-syntax-entry ?\- "w")
 216     (dolist (arg args doc)
 217       (setq doc (replace-regexp-in-string
 218                  ;; This is heuristic, but covers all common cases
 219                  ;; except ARG1-ARG2
 220                  (concat "\\<"                   ; beginning of word
 221                          "\\(?:[a-z-]*-\\)?"     ; for xxx-ARG
 222                          "\\("
 223                          (regexp-quote arg)
 224                          "\\)"
 225                          "\\(?:es\\|s\\|th\\)?"  ; for ARGth, ARGs
 226                          "\\(?:-[a-z0-9-]+\\)?"  ; for ARG-xxx, ARG-n
 227                          "\\(?:-[{([<`\"].*?\\)?"; for ARG-{x}, (x), <x>, [x], `x'
 228                          "\\>")                  ; end of word
 229                  (help-highlight-arg arg)
 230                  doc t t 1)))))
 231
 232 (defun help-highlight-arguments (usage doc &rest args)
 233   (when (and usage (string-match "^(" usage))
 234     (with-temp-buffer
 235       (insert usage)
 236       (goto-char (point-min))
 237       (let ((case-fold-search nil)
 238             (next (not (or args (looking-at "\\["))))
 239             (opt nil))
 240         ;; Make a list of all arguments
 241         (skip-chars-forward "^ ")
 242         (while next
 243           (or opt (not (looking-at " &")) (setq opt t))
 244           (if (not (re-search-forward " \\([\\[(]*\\)\\([^] &)\.]+\\)" nil t))
 245               (setq next nil)
 246             (setq args (cons (match-string 2) args))
 247             (when (and opt (string= (match-string 1) "("))
 248               ;; A pesky CL-style optional argument with default value,
 249               ;; so let's skip over it
 250               (search-backward "(")
 251               (goto-char (scan-sexps (point) 1)))))
 252         ;; Highlight aguments in the USAGE string
 253         (setq usage (help-do-arg-highlight (buffer-string) args))
 254         ;; Highlight arguments in the DOC string
 255         (setq doc (and doc (help-do-arg-highlight doc args))))))
 256   ;; Return value is like the one from help-split-fundoc, but highlighted
 257   (cons usage doc))
 258
 259 ;; The following function was compiled from the former functions
 260 ;; `describe-simplify-lib-file-name' and `find-source-lisp-file' with
 261 ;; some excerpts from `describe-function-1' and `describe-variable'.
 262 ;; The only additional twists provided are (1) locate the defining file
 263 ;; for autoloaded functions, and (2) give preference to files in the
 264 ;; "install directory" (directories found via `load-path') rather than
 265 ;; to files in the "compile directory" (directories found by searching
 266 ;; the loaddefs.el file).  We autoload it because it's also used by
 267 ;; `describe-face' (instead of `describe-simplify-lib-file-name').
 268
 269 ;;;###autoload
 270 (defun find-lisp-object-file-name (object type)
 271   "Guess the file that defined the Lisp object OBJECT, of type TYPE.
 272 OBJECT should be a symbol associated with a function, variable, or face;
 273   alternatively, it can be a function definition.
 274 If TYPE is `defvar', search for a variable definition.
 275 If TYPE is `defface', search for a face definition.
 276 If TYPE is the value returned by `symbol-function' for a function symbol,
 277  search for a function definition.
 278
 279 The return value is the absolute name of a readable file where OBJECT is
 280 defined.  If several such files exist, preference is given to a file
 281 found via `load-path'.  The return value can also be `C-source', which
 282 means that OBJECT is a function or variable defined in C.  If no
 283 suitable file is found, return nil."
 284   (let* ((autoloaded (eq (car-safe type) 'autoload))
 285          (file-name (or (and autoloaded (nth 1 type))
 286                         (symbol-file
 287                          object (if (memq type (list 'defvar 'defface))
 288                                     type
 289                                   'defun)))))
 290     (cond
 291      (autoloaded
 292       ;; An autoloaded function: Locate the file since `symbol-function'
 293       ;; has only returned a bare string here.
 294       (setq file-name
 295             (locate-file file-name load-path '(".el" ".elc") 'readable)))
 296      ((and (stringp file-name)
 297            (string-match "[.]*loaddefs.el\\'" file-name))
 298       ;; An autoloaded variable or face.  Visit loaddefs.el in a buffer
 299       ;; and try to extract the defining file.  The following form is
 300       ;; from `describe-function-1' and `describe-variable'.
 301       (let ((location
 302              (condition-case nil
 303                  (find-function-search-for-symbol object nil file-name)
 304                (error nil))))
 305         (when (cdr location)
 306           (with-current-buffer (car location)
 307             (goto-char (cdr location))
 308             (when (re-search-backward
 309                    "^;;; Generated autoloads from \\(.*\\)" nil t)
 310               (setq file-name
 311                     (locate-file
 312                      (file-name-sans-extension
 313                       (match-string-no-properties 1))
 314                      load-path '(".el" ".elc") 'readable))))))))
 315
 316     (cond
 317      ((and (not file-name) (subrp type))
 318       ;; A built-in function.  The form is from `describe-function-1'.
 319       (if (get-buffer " *DOC*")
 320           (help-C-file-name type 'subr)
 321         'C-source))
 322      ((and (not file-name) (symbolp object)
 323            (integerp (get object 'variable-documentation)))
 324       ;; A variable defined in C.  The form is from `describe-variable'.
 325       (if (get-buffer " *DOC*")
 326           (help-C-file-name object 'var)
 327         'C-source))
 328      ((not (stringp file-name))
 329       ;; If we don't have a file-name string by now, we lost.
 330       nil)
 331      ;; Now, `file-name' should have become an absolute file name.
 332      ;; For files loaded from ~/.emacs.elc, try ~/.emacs.
 333      ((let (fn)
 334         (and (string-equal file-name
 335                            (expand-file-name ".emacs.elc" "~"))
 336              (file-readable-p (setq fn (expand-file-name ".emacs" "~")))
 337              fn)))
 338      ;; When the Elisp source file can be found in the install
 339      ;; directory, return the name of that file.
 340      ((let ((lib-name
 341              (if (string-match "[.]elc\\'" file-name)
 342                  (substring-no-properties file-name 0 -1)
 343                file-name)))
 344         (or (and (file-readable-p lib-name) lib-name)
 345             ;; The library might be compressed.
 346             (and (file-readable-p (concat lib-name ".gz")) lib-name))))
 347      ((let* ((lib-name (file-name-nondirectory file-name))
 348              ;; The next form is from `describe-simplify-lib-file-name'.
 349              (file-name
 350               ;; Try converting the absolute file name to a library
 351               ;; name, convert that back to a file name and see if we
 352               ;; get the original one.  If so, they are equivalent.
 353               (if (equal file-name (locate-file lib-name load-path '("")))
 354                   (if (string-match "[.]elc\\'" lib-name)
 355                       (substring-no-properties lib-name 0 -1)
 356                     lib-name)
 357                 file-name))
 358              ;; The next three forms are from `find-source-lisp-file'.
 359              (elc-file (locate-file
 360                         (concat file-name
 361                                 (if (string-match "\\.el\\'" file-name)
 362                                     "c"
 363                                   ".elc"))
 364                         load-path nil 'readable))
 365              (str (when elc-file
 366                     (with-temp-buffer
 367                       (insert-file-contents-literally elc-file nil 0 256)
 368                       (buffer-string))))
 369              (src-file (and str
 370                             (string-match ";;; from file \\(.*\\.el\\)" str)
 371                             (match-string 1 str))))
 372         (and src-file (file-readable-p src-file) src-file))))))
 373
 374 (declare-function ad-get-advice-info "advice" (function))
 375
 376 ;;;###autoload
 377 (defun describe-function-1 (function)
 378   (let* ((advised (and (symbolp function) (featurep 'advice)
 379                        (ad-get-advice-info function)))
 380          ;; If the function is advised, use the symbol that has the
 381          ;; real definition, if that symbol is already set up.
 382          (real-function
 383           (or (and advised
 384                    (let ((origname (cdr (assq 'origname advised))))
 385                      (and (fboundp origname) origname)))
 386               function))
 387          ;; Get the real definition.
 388          (def (if (symbolp real-function)
 389                   (symbol-function real-function)
 390                 function))
 391          file-name string
 392          (beg (if (commandp def) "an interactive " "a "))
 393          (pt1 (with-current-buffer (help-buffer) (point)))
 394          errtype)
 395     (setq string
 396           (cond ((or (stringp def) (vectorp def))
 397                  "a keyboard macro")
 398                 ((subrp def)
 399                  (if (eq 'unevalled (cdr (subr-arity def)))
 400                      (concat beg "special form")
 401                    (concat beg "built-in function")))
 402                 ((byte-code-function-p def)
 403                  (concat beg "compiled Lisp function"))
 404                 ((symbolp def)
 405                  (while (and (fboundp def)
 406                              (symbolp (symbol-function def)))
 407                    (setq def (symbol-function def)))
 408                  ;; Handle (defalias 'foo 'bar), where bar is undefined.
 409                  (or (fboundp def) (setq errtype 'alias))
 410                  (format "an alias for `%s'" def))
 411                 ((eq (car-safe def) 'lambda)
 412                  (concat beg "Lisp function"))
 413                 ((eq (car-safe def) 'macro)
 414                  "a Lisp macro")
 415                 ((eq (car-safe def) 'closure)
 416                  (concat beg "Lisp closure"))
 417                 ((eq (car-safe def) 'autoload)
 418                  (format "%s autoloaded %s"
 419                          (if (commandp def) "an interactive" "an")
 420                          (if (eq (nth 4 def) 'keymap) "keymap"
 421                            (if (nth 4 def) "Lisp macro" "Lisp function"))))
 422                 ((keymapp def)
 423                  (let ((is-full nil)
 424                        (elts (cdr-safe def)))
 425                    (while elts
 426                      (if (char-table-p (car-safe elts))
 427                          (setq is-full t
 428                                elts nil))
 429                      (setq elts (cdr-safe elts)))
 430                    (if is-full
 431                        "a full keymap"
 432                      "a sparse keymap")))
 433                 (t "")))
 434     (princ string)
 435     (if (eq errtype 'alias)
 436         (princ ",\nwhich is not defined.  Please make a bug report.")
 437       (with-current-buffer standard-output
 438         (save-excursion
 439           (save-match-data
 440             (when (re-search-backward "alias for `\\([^`']+\\)'" nil t)
 441               (help-xref-button 1 'help-function def)))))
 442
 443       (setq file-name (find-lisp-object-file-name function def))
 444       (when file-name
 445         (princ " in `")
 446         ;; We used to add .el to the file name,
 447         ;; but that's completely wrong when the user used load-file.
 448         (princ (if (eq file-name 'C-source)
 449                    "C source code"
 450                  (file-name-nondirectory file-name)))
 451         (princ "'")
 452         ;; Make a hyperlink to the library.
 453         (with-current-buffer standard-output
 454           (save-excursion
 455             (re-search-backward "`\\([^`']+\\)'" nil t)
 456             (help-xref-button 1 'help-function-def function file-name))))
 457       (princ ".")
 458       (with-current-buffer (help-buffer)
 459         (fill-region-as-paragraph (save-excursion (goto-char pt1) (forward-line 0) (point))
 460                                   (point)))
 461       (terpri)(terpri)
 462       (when (commandp function)
 463         (let ((pt2 (with-current-buffer (help-buffer) (point)))
 464               (remapped (command-remapping function)))
 465           (unless (memq remapped '(ignore undefined))
 466             (let ((keys (where-is-internal
 467                          (or remapped function) overriding-local-map nil nil))
 468                   non-modified-keys)
 469               (if (and (eq function 'self-insert-command)
 470                        (vectorp (car-safe keys))
 471                        (consp (aref (car keys) 0)))
 472                   (princ "It is bound to many ordinary text characters.\n")
 473                 ;; Which non-control non-meta keys run this command?
 474                 (dolist (key keys)
 475                   (if (member (event-modifiers (aref key 0)) '(nil (shift)))
 476                       (push key non-modified-keys)))
 477                 (when remapped
 478                   (princ "It is remapped to `")
 479                   (princ (symbol-name remapped))
 480                   (princ "'"))
 481
 482                 (when keys
 483                   (princ (if remapped ", which is bound to " "It is bound to "))
 484                   ;; If lots of ordinary text characters run this command,
 485                   ;; don't mention them one by one.
 486                   (if (< (length non-modified-keys) 10)
 487                       (princ (mapconcat 'key-description keys ", "))
 488                     (dolist (key non-modified-keys)
 489                       (setq keys (delq key keys)))
 490                     (if keys
 491                         (progn
 492                           (princ (mapconcat 'key-description keys ", "))
 493                           (princ ", and many ordinary text characters"))
 494                       (princ "many ordinary text characters"))))
 495                 (when (or remapped keys non-modified-keys)
 496                   (princ ".")
 497                   (terpri)))))
 498
 499           (with-current-buffer (help-buffer)
 500             (fill-region-as-paragraph pt2 (point))
 501             (unless (looking-back "\n\n")
 502               (terpri)))))
 503       ;; Note that list* etc do not get this property until
 504       ;; cl-hack-byte-compiler runs, after bytecomp is loaded.
 505       (when (and (symbolp function)
 506                  (eq (get function 'byte-compile)
 507                      'cl-byte-compile-compiler-macro))
 508         (princ "This function has a compiler macro")
 509         (let ((lib (get function 'compiler-macro-file)))
 510           (when (stringp lib)
 511             (princ (format " in `%s'" lib))
 512             (with-current-buffer standard-output
 513               (save-excursion
 514                 (re-search-backward "`\\([^`']+\\)'" nil t)
 515                 (help-xref-button 1 'help-function-cmacro function lib)))))
 516         (princ ".\n\n"))
 517       (let* ((advertised (gethash def advertised-signature-table t))
 518              (arglist (if (listp advertised)
 519                           advertised (help-function-arglist def)))
 520              (doc (condition-case err (documentation function)
 521                     (error (format "No Doc! %S" err))))
 522              (usage (help-split-fundoc doc function)))
 523         (with-current-buffer standard-output
 524           ;; If definition is a keymap, skip arglist note.
 525           (unless (keymapp function)
 526             (if usage (setq doc (cdr usage)))
 527             (let* ((use (cond
 528                          ((and usage (not (listp advertised))) (car usage))
 529                          ((listp arglist)
 530                           (format "%S" (help-make-usage function arglist)))
 531                          ((stringp arglist) arglist)
 532                          ;; Maybe the arglist is in the docstring of a symbol
 533                          ;; this one is aliased to.
 534                          ((let ((fun real-function))
 535                             (while (and (symbolp fun)
 536                                         (setq fun (symbol-function fun))
 537                                         (not (setq usage (help-split-fundoc
 538                                                           (documentation fun)
 539                                                           function)))))
 540                             usage)
 541                           (car usage))
 542                          ((or (stringp def)
 543                               (vectorp def))
 544                           (format "\nMacro: %s" (format-kbd-macro def)))
 545                          (t "[Missing arglist.  Please make a bug report.]")))
 546                    (high (help-highlight-arguments use doc)))
 547               (let ((fill-begin (point)))
 548                 (insert (car high) "\n")
 549                 (fill-region fill-begin (point)))
 550               (setq doc (cdr high))))
 551           (let* ((obsolete (and
 552                             ;; function might be a lambda construct.
 553                             (symbolp function)
 554                             (get function 'byte-obsolete-info)))
 555                  (use (car obsolete)))
 556             (when obsolete
 557               (princ "\nThis function is obsolete")
 558               (when (nth 2 obsolete)
 559                 (insert (format " since %s" (nth 2 obsolete))))
 560               (insert (cond ((stringp use) (concat ";\n" use))
 561                             (use (format ";\nuse `%s' instead." use))
 562                             (t "."))
 563                       "\n"))
 564             (insert "\n"
 565                     (or doc "Not documented."))))))))
 566
 567 \f
 568 ;; Variables
 569
 570 ;;;###autoload
 571 (defun variable-at-point (&optional any-symbol)
 572   "Return the bound variable symbol found at or before point.
 573 Return 0 if there is no such symbol.
 574 If ANY-SYMBOL is non-nil, don't insist the symbol be bound."
 575   (with-syntax-table emacs-lisp-mode-syntax-table
 576     (or (condition-case ()
 577             (save-excursion
 578               (skip-chars-forward "'")
 579               (or (not (zerop (skip-syntax-backward "_w")))
 580                   (eq (char-syntax (following-char)) ?w)
 581                   (eq (char-syntax (following-char)) ?_)
 582                   (forward-sexp -1))
 583               (skip-chars-forward "'")
 584               (let ((obj (read (current-buffer))))
 585                 (and (symbolp obj) (boundp obj) obj)))
 586           (error nil))
 587         (let* ((str (find-tag-default))
 588                (sym (if str (intern-soft str))))
 589           (if (and sym (or any-symbol (boundp sym)))
 590               sym
 591             (save-match-data
 592               (when (and str (string-match "\\`\\W*\\(.*?\\)\\W*\\'" str))
 593                 (setq sym (intern-soft (match-string 1 str)))
 594                 (and (or any-symbol (boundp sym)) sym)))))
 595         0)))
 596
 597 (defun describe-variable-custom-version-info (variable)
 598   (let ((custom-version (get variable 'custom-version))
 599         (cpv (get variable 'custom-package-version))
 600         (output nil))
 601     (if custom-version
 602         (setq output
 603               (format "This variable was introduced, or its default value was changed, in\nversion %s of Emacs.\n"
 604                       custom-version))
 605       (when cpv
 606         (let* ((package (car-safe cpv))
 607                (version (if (listp (cdr-safe cpv))
 608                             (car (cdr-safe cpv))
 609                           (cdr-safe cpv)))
 610                (pkg-versions (assq package customize-package-emacs-version-alist))
 611                (emacsv (cdr (assoc version pkg-versions))))
 612           (if (and package version)
 613               (setq output
 614                     (format (concat "This variable was introduced, or its default value was changed, in\nversion %s of the %s package"
 615                                     (if emacsv
 616                                         (format " that is part of Emacs %s" emacsv))
 617                                     ".\n")
 618                             version package))))))
 619     output))
 620
 621 ;;;###autoload
 622 (defun describe-variable (variable &optional buffer frame)
 623   "Display the full documentation of VARIABLE (a symbol).
 624 Returns the documentation as a string, also.
 625 If VARIABLE has a buffer-local value in BUFFER or FRAME
 626 \(default to the current buffer and current frame),
 627 it is displayed along with the global value."
 628   (interactive
 629    (let ((v (variable-at-point))
 630          (enable-recursive-minibuffers t)
 631          val)
 632      (setq val (completing-read (if (symbolp v)
 633                                     (format
 634                                      "Describe variable (default %s): " v)
 635                                   "Describe variable: ")
 636                                 obarray
 637                                 (lambda (vv)
 638                                   (or (special-variable-p vv)
 639                                       (get vv 'variable-documentation)))
 640                                 t nil nil
 641                                 (if (symbolp v) (symbol-name v))))
 642      (list (if (equal val "")
 643                v (intern val)))))
 644   (let (file-name)
 645     (unless (buffer-live-p buffer) (setq buffer (current-buffer)))
 646     (unless (frame-live-p frame) (setq frame (selected-frame)))
 647     (if (not (symbolp variable))
 648         (message "You did not specify a variable")
 649       (save-excursion
 650         (let ((valvoid (not (with-current-buffer buffer (boundp variable))))
 651               val val-start-pos locus)
 652           ;; Extract the value before setting up the output buffer,
 653           ;; in case `buffer' *is* the output buffer.
 654           (unless valvoid
 655             (with-selected-frame frame
 656               (with-current-buffer buffer
 657                 (setq val (symbol-value variable)
 658                       locus (variable-binding-locus variable)))))
 659           (help-setup-xref (list #'describe-variable variable buffer)
 660                            (called-interactively-p 'interactive))
 661           (with-help-window (help-buffer)
 662             (with-current-buffer buffer
 663               (prin1 variable)
 664               (setq file-name (find-lisp-object-file-name variable 'defvar))
 665
 666               (if file-name
 667                   (progn
 668                     (princ " is a variable defined in `")
 669                     (princ (if (eq file-name 'C-source)
 670                                "C source code"
 671                              (file-name-nondirectory file-name)))
 672                     (princ "'.\n")
 673                     (with-current-buffer standard-output
 674                       (save-excursion
 675                         (re-search-backward "`\\([^`']+\\)'" nil t)
 676                         (help-xref-button 1 'help-variable-def
 677                                           variable file-name)))
 678                     (if valvoid
 679                         (princ "It is void as a variable.")
 680                       (princ "Its ")))
 681                 (if valvoid
 682                     (princ " is void as a variable.")
 683                   (princ "'s "))))
 684             (unless valvoid
 685               (with-current-buffer standard-output
 686                 (setq val-start-pos (point))
 687                 (princ "value is ")
 688                 (let ((from (point)))
 689                   (terpri)
 690                   (pp val)
 691                   (if (< (point) (+ 68 (line-beginning-position 0)))
 692                       (delete-region from (1+ from))
 693                     (delete-region (1- from) from))
 694                   (let* ((sv (get variable 'standard-value))
 695                          (origval (and (consp sv)
 696                                        (condition-case nil
 697                                            (eval (car sv))
 698                                          (error :help-eval-error)))))
 699                     (when (and (consp sv)
 700                                (not (equal origval val))
 701                                (not (equal origval :help-eval-error)))
 702                       (princ "\nOriginal value was \n")
 703                       (setq from (point))
 704                       (pp origval)
 705                       (if (< (point) (+ from 20))
 706                           (delete-region (1- from) from)))))))
 707             (terpri)
 708             (when locus
 709               (if (bufferp locus)
 710                   (princ (format "%socal in buffer %s; "
 711                                  (if (get variable 'permanent-local)
 712                                      "Permanently l" "L")
 713                                  (buffer-name)))
 714                 (princ (format "It is a frame-local variable; ")))
 715               (if (not (default-boundp variable))
 716                   (princ "globally void")
 717                 (let ((val (default-value variable)))
 718                   (with-current-buffer standard-output
 719                     (princ "global value is ")
 720                     (terpri)
 721                     ;; Fixme: pp can take an age if you happen to
 722                     ;; ask for a very large expression.  We should
 723                     ;; probably print it raw once and check it's a
 724                     ;; sensible size before prettyprinting.  -- fx
 725                     (let ((from (point)))
 726                       (pp val)
 727                       ;; See previous comment for this function.
 728                       ;; (help-xref-on-pp from (point))
 729                       (if (< (point) (+ from 20))
 730                           (delete-region (1- from) from))))))
 731               (terpri))
 732
 733             ;; If the value is large, move it to the end.
 734             (with-current-buffer standard-output
 735               (when (> (count-lines (point-min) (point-max)) 10)
 736                 ;; Note that setting the syntax table like below
 737                 ;; makes forward-sexp move over a `'s' at the end
 738                 ;; of a symbol.
 739                 (set-syntax-table emacs-lisp-mode-syntax-table)
 740                 (goto-char val-start-pos)
 741                 ;; The line below previously read as
 742                 ;; (delete-region (point) (progn (end-of-line) (point)))
 743                 ;; which suppressed display of the buffer local value for
 744                 ;; large values.
 745                 (when (looking-at "value is") (replace-match ""))
 746                 (save-excursion
 747                   (insert "\n\nValue:")
 748                   (set (make-local-variable 'help-button-cache)
 749                        (point-marker)))
 750                 (insert "value is shown ")
 751                 (insert-button "below"
 752                                'action help-button-cache
 753                                'follow-link t
 754                                'help-echo "mouse-2, RET: show value")
 755                 (insert ".\n")))
 756             (terpri)
 757
 758             (let* ((alias (condition-case nil
 759                               (indirect-variable variable)
 760                             (error variable)))
 761                    (obsolete (get variable 'byte-obsolete-variable))
 762                    (use (car obsolete))
 763                    (safe-var (get variable 'safe-local-variable))
 764                    (doc (or (documentation-property variable 'variable-documentation)
 765                             (documentation-property alias 'variable-documentation)))
 766                    (extra-line nil))
 767               ;; Add a note for variables that have been make-var-buffer-local.
 768               (when (and (local-variable-if-set-p variable)
 769                          (or (not (local-variable-p variable))
 770                              (with-temp-buffer
 771                                (local-variable-if-set-p variable))))
 772                 (setq extra-line t)
 773                 (princ "  Automatically becomes buffer-local when set in any fashion.\n"))
 774
 775               ;; Mention if it's an alias
 776               (unless (eq alias variable)
 777                 (setq extra-line t)
 778                 (princ (format "  This variable is an alias for `%s'.\n" alias)))
 779
 780               (when obsolete
 781                 (setq extra-line t)
 782                 (princ "  This variable is obsolete")
 783                 (if (cdr obsolete) (princ (format " since %s" (cdr obsolete))))
 784                 (princ (cond ((stringp use) (concat ";\n  " use))
 785                              (use (format ";\n  use `%s' instead." (car obsolete)))
 786                              (t ".")))
 787                 (terpri))
 788
 789               (when (member (cons variable val) file-local-variables-alist)
 790                 (setq extra-line t)
 791                 (if (member (cons variable val) dir-local-variables-alist)
 792                     (let ((file (and (buffer-file-name)
 793                                       (not (file-remote-p (buffer-file-name)))
 794                                       (dir-locals-find-file
 795                                        (buffer-file-name))))
 796                           (type "file"))
 797                       (princ "  This variable is a directory local variable")
 798                       (when file
 799                         (if (consp file) ; result from cache
 800                             ;; If the cache element has an mtime, we
 801                             ;; assume it came from a file.
 802                             (if (nth 2 file)
 803                                 (setq file (expand-file-name
 804                                             dir-locals-file (car file)))
 805                               ;; Otherwise, assume it was set directly.
 806                               (setq type "directory")))
 807                         (princ (format "\n  from the %s \"%s\"" type file)))
 808                       (princ ".\n"))
 809                   (princ "  This variable is a file local variable.\n")))
 810
 811               (when (memq variable ignored-local-variables)
 812                 (setq extra-line t)
 813                 (princ "  This variable is ignored when used as a file local \
 814 variable.\n"))
 815
 816               ;; Can be both risky and safe, eg auto-fill-function.
 817               (when (risky-local-variable-p variable)
 818                 (setq extra-line t)
 819                 (princ "  This variable is potentially risky when used as a \
 820 file local variable.\n")
 821                 (when (assq variable safe-local-variable-values)
 822                   (princ "  However, you have added it to \
 823 `safe-local-variable-values'.\n")))
 824
 825               (when safe-var
 826                 (setq extra-line t)
 827                 (princ "  This variable is safe as a file local variable ")
 828                 (princ "if its value\n  satisfies the predicate ")
 829                 (princ (if (byte-code-function-p safe-var)
 830                            "which is byte-compiled expression.\n"
 831                          (format "`%s'.\n" safe-var))))
 832
 833               (if extra-line (terpri))
 834               (princ "Documentation:\n")
 835               (with-current-buffer standard-output
 836                 (insert (or doc "Not documented as a variable."))))
 837
 838             ;; Make a link to customize if this variable can be customized.
 839             (when (custom-variable-p variable)
 840               (let ((customize-label "customize"))
 841                 (terpri)
 842                 (terpri)
 843                 (princ (concat "You can " customize-label " this variable."))
 844                 (with-current-buffer standard-output
 845                   (save-excursion
 846                     (re-search-backward
 847                      (concat "\\(" customize-label "\\)") nil t)
 848                     (help-xref-button 1 'help-customize-variable variable))))
 849               ;; Note variable's version or package version
 850               (let ((output (describe-variable-custom-version-info variable)))
 851                 (when output
 852                   (terpri)
 853                   (terpri)
 854                   (princ output))))
 855
 856             (with-current-buffer standard-output
 857               ;; Return the text we displayed.
 858               (buffer-string))))))))
 859
 860
 861 ;;;###autoload
 862 (defun describe-syntax (&optional buffer)
 863   "Describe the syntax specifications in the syntax table of BUFFER.
 864 The descriptions are inserted in a help buffer, which is then displayed.
 865 BUFFER defaults to the current buffer."
 866   (interactive)
 867   (setq buffer (or buffer (current-buffer)))
 868   (help-setup-xref (list #'describe-syntax buffer)
 869                    (called-interactively-p 'interactive))
 870   (with-help-window (help-buffer)
 871     (let ((table (with-current-buffer buffer (syntax-table))))
 872       (with-current-buffer standard-output
 873         (describe-vector table 'internal-describe-syntax-value)
 874         (while (setq table (char-table-parent table))
 875           (insert "\nThe parent syntax table is:")
 876           (describe-vector table 'internal-describe-syntax-value))))))
 877
 878 (defun help-describe-category-set (value)
 879   (insert (cond
 880            ((null value) "default")
 881            ((char-table-p value) "deeper char-table ...")
 882            (t (condition-case err
 883                   (category-set-mnemonics value)
 884                 (error "invalid"))))))
 885
 886 ;;;###autoload
 887 (defun describe-categories (&optional buffer)
 888   "Describe the category specifications in the current category table.
 889 The descriptions are inserted in a buffer, which is then displayed.
 890 If BUFFER is non-nil, then describe BUFFER's category table instead.
 891 BUFFER should be a buffer or a buffer name."
 892   (interactive)
 893   (setq buffer (or buffer (current-buffer)))
 894   (help-setup-xref (list #'describe-categories buffer)
 895                    (called-interactively-p 'interactive))
 896   (with-help-window (help-buffer)
 897     (let* ((table (with-current-buffer buffer (category-table)))
 898            (docs (char-table-extra-slot table 0)))
 899       (if (or (not (vectorp docs)) (/= (length docs) 95))
 900           (error "Invalid first extra slot in this category table\n"))
 901       (with-current-buffer standard-output
 902         (insert "Legend of category mnemonics (see the tail for the longer description)\n")
 903         (let ((pos (point)) (items 0) lines n)
 904           (dotimes (i 95)
 905             (if (aref docs i) (setq items (1+ items))))
 906           (setq lines (1+ (/ (1- items) 4)))
 907           (setq n 0)
 908           (dotimes (i 95)
 909             (let ((elt (aref docs i)))
 910               (when elt
 911                 (string-match ".*" elt)
 912                 (setq elt (match-string 0 elt))
 913                 (if (>= (length elt) 17)
 914                     (setq elt (concat (substring elt 0 14) "...")))
 915                 (if (< (point) (point-max))
 916                     (move-to-column (* 20 (/ n lines)) t))
 917                 (insert (+ i ?\s) ?: elt)
 918                 (if (< (point) (point-max))
 919                     (forward-line 1)
 920                   (insert "\n"))
 921                 (setq n (1+ n))
 922                 (if (= (% n lines) 0)
 923                     (goto-char pos))))))
 924         (goto-char (point-max))
 925         (insert "\n"
 926                 "character(s)\tcategory mnemonics\n"
 927                 "------------\t------------------")
 928         (describe-vector table 'help-describe-category-set)
 929         (insert "Legend of category mnemonics:\n")
 930         (dotimes (i 95)
 931           (let ((elt (aref docs i)))
 932             (when elt
 933               (if (string-match "\n" elt)
 934                   (setq elt (substring elt (match-end 0))))
 935               (insert (+ i ?\s) ": " elt "\n"))))
 936         (while (setq table (char-table-parent table))
 937           (insert "\nThe parent category table is:")
 938           (describe-vector table 'help-describe-category-set))))))
 939
 940 \f
 941 ;;; Replacements for old lib-src/ programs.  Don't seem especially useful.
 942
 943 ;; Replaces lib-src/digest-doc.c.
 944 ;;;###autoload
 945 (defun doc-file-to-man (file)
 946   "Produce an nroff buffer containing the doc-strings from the DOC file."
 947   (interactive (list (read-file-name "Name of DOC file: " doc-directory
 948                                      internal-doc-file-name t)))
 949   (or (file-readable-p file)
 950       (error "Cannot read file `%s'" file))
 951   (pop-to-buffer (generate-new-buffer "*man-doc*"))
 952   (setq buffer-undo-list t)
 953   (insert ".TH \"Command Summary for GNU Emacs\"\n"
 954           ".AU Richard M. Stallman\n")
 955   (insert-file-contents file)
 956   (let (notfirst)
 957     (while (search-forward "\1f" nil 'move)
 958       (if (looking-at "S")
 959           (delete-region (1- (point)) (line-end-position))
 960         (delete-char -1)
 961         (if notfirst
 962             (insert "\n.DE\n")
 963           (setq notfirst t))
 964         (insert "\n.SH ")
 965         (insert (if (looking-at "F") "Function " "Variable "))
 966         (delete-char 1)
 967         (forward-line 1)
 968         (insert ".DS L\n"))))
 969   (insert "\n.DE\n")
 970   (setq buffer-undo-list nil)
 971   (nroff-mode))
 972
 973 ;; Replaces lib-src/sorted-doc.c.
 974 ;;;###autoload
 975 (defun doc-file-to-info (file)
 976   "Produce a texinfo buffer with sorted doc-strings from the DOC file."
 977   (interactive (list (read-file-name "Name of DOC file: " doc-directory
 978                                      internal-doc-file-name t)))
 979   (or (file-readable-p file)
 980       (error "Cannot read file `%s'" file))
 981   (let ((i 0) type name doc alist)
 982     (with-temp-buffer
 983       (insert-file-contents file)
 984       ;; The characters "@{}" need special treatment.
 985       (while (re-search-forward "[@{}]" nil t)
 986         (backward-char)
 987         (insert "@")
 988         (forward-char 1))
 989       (goto-char (point-min))
 990       (while (search-forward "\1f" nil t)
 991         (unless (looking-at "S")
 992           (setq type (char-after)
 993                 name (buffer-substring (1+ (point)) (line-end-position))
 994                 doc (buffer-substring (line-beginning-position 2)
 995                                       (if (search-forward  "\1f" nil 'move)
 996                                           (1- (point))
 997                                         (point)))
 998                 alist (cons (list name type doc) alist))
 999           (backward-char 1))))
1000     (pop-to-buffer (generate-new-buffer "*info-doc*"))
1001     (setq buffer-undo-list t)
1002     ;; Write the output header.
1003     (insert "\\input texinfo  @c -*-texinfo-*-\n"
1004             "@setfilename emacsdoc.info\n"
1005             "@settitle Command Summary for GNU Emacs\n"
1006             "@finalout\n"
1007             "\n@node Top\n"
1008             "@unnumbered Command Summary for GNU Emacs\n\n"
1009             "@table @asis\n\n"
1010             "@iftex\n"
1011             "@global@let@ITEM@item\n"
1012             "@def@item{@filbreak@vskip5pt@ITEM}\n"
1013             "@font@tensy cmsy10 scaled @magstephalf\n"
1014             "@font@teni cmmi10 scaled @magstephalf\n"
1015             "@def\\{{@tensy@char110}}\n" ; this backslash goes with cmr10
1016             "@def|{{@tensy@char106}}\n"
1017             "@def@{{{@tensy@char102}}\n"
1018             "@def@}{{@tensy@char103}}\n"
1019             "@def<{{@teni@char62}}\n"
1020             "@def>{{@teni@char60}}\n"
1021             "@chardef@@64\n"
1022             "@catcode43=12\n"
1023             "@tableindent-0.2in\n"
1024             "@end iftex\n")
1025     ;; Sort the array by name; within each name, by type (functions first).
1026     (setq alist (sort alist (lambda (e1 e2)
1027                               (if (string-equal (car e1) (car e2))
1028                                   (<= (cadr e1) (cadr e2))
1029                                 (string-lessp (car e1) (car e2))))))
1030     ;; Print each function.
1031     (dolist (e alist)
1032       (insert "\n@item "
1033               (if (char-equal (cadr e) ?\F) "Function" "Variable")
1034               " @code{" (car e) "}\n@display\n"
1035               (nth 2 e)
1036               "\n@end display\n")
1037       ;; Try to avoid a save size overflow in the TeX output routine.
1038       (if (zerop (setq i (% (1+ i) 100)))
1039           (insert "\n@end table\n@table @asis\n")))
1040     (insert "@end table\n"
1041             "@bye\n")
1042     (setq buffer-undo-list nil)
1043     (texinfo-mode)))
1044
1045 (provide 'help-fns)
1046
1047 ;;; help-fns.el ends here