lisp/help-fns.el

   1 ;;; help-fns.el --- Complex help functions -*- lexical-binding: t -*-
   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 &optional preserve-names)
 103   "Return a formal argument list for the function DEF.
 104 IF PRESERVE-NAMES is non-nil, return a formal arglist that uses
 105 the same names as used in the original source code, when possible."
 106   ;; Handle symbols aliased to other symbols.
 107   (if (and (symbolp def) (fboundp def)) (setq def (indirect-function def)))
 108   ;; If definition is a macro, find the function inside it.
 109   (if (eq (car-safe def) 'macro) (setq def (cdr def)))
 110   (cond
 111    ((and (byte-code-function-p def) (listp (aref def 0))) (aref def 0))
 112    ((eq (car-safe def) 'lambda) (nth 1 def))
 113    ((eq (car-safe def) 'closure) (nth 2 def))
 114    ((or (and (byte-code-function-p def) (integerp (aref def 0)))
 115         (subrp def))
 116     (or (when preserve-names
 117           (let* ((doc (condition-case nil (documentation def) (error nil)))
 118                  (docargs (if doc (car (help-split-fundoc doc nil))))
 119                  (arglist (if docargs
 120                               (cdar (read-from-string (downcase docargs)))))
 121                  (valid t))
 122             ;; Check validity.
 123             (dolist (arg arglist)
 124               (unless (and (symbolp arg)
 125                            (let ((name (symbol-name arg)))
 126                              (if (eq (aref name 0) ?&)
 127                                  (memq arg '(&rest &optional))
 128                                (not (string-match "\\." name)))))
 129                 (setq valid nil)))
 130             (when valid arglist)))
 131         (let* ((args-desc (if (not (subrp def))
 132                               (aref def 0)
 133                             (let ((a (subr-arity def)))
 134                               (logior (car a)
 135                                       (if (numberp (cdr a))
 136                                           (lsh (cdr a) 8)
 137                                         (lsh 1 7))))))
 138                (max (lsh args-desc -8))
 139                (min (logand args-desc 127))
 140                (rest (logand args-desc 128))
 141                (arglist ()))
 142           (dotimes (i min)
 143             (push (intern (concat "arg" (number-to-string (1+ i)))) arglist))
 144           (when (> max min)
 145             (push '&optional arglist)
 146             (dotimes (i (- max min))
 147               (push (intern (concat "arg" (number-to-string (+ 1 i min))))
 148                     arglist)))
 149           (unless (zerop rest) (push '&rest arglist) (push 'rest arglist))
 150           (nreverse arglist))))
 151    ((and (eq (car-safe def) 'autoload) (not (eq (nth 4 def) 'keymap)))
 152     "[Arg list not available until function definition is loaded.]")
 153    (t t)))
 154
 155 ;; FIXME: Move to subr.el?
 156 (defun help-make-usage (function arglist)
 157   (cons (if (symbolp function) function 'anonymous)
 158         (mapcar (lambda (arg)
 159                   (if (not (symbolp arg))
 160                       (if (and (consp arg) (symbolp (car arg)))
 161                           ;; CL style default values for optional args.
 162                           (cons (intern (upcase (symbol-name (car arg))))
 163                                 (cdr arg))
 164                         arg)
 165                     (let ((name (symbol-name arg)))
 166                       (cond
 167                        ((string-match "\\`&" name) arg)
 168                        ((string-match "\\`_" name)
 169                         (intern (upcase (substring name 1))))
 170                        (t (intern (upcase name)))))))
 171                 arglist)))
 172
 173 ;; Could be this, if we make symbol-file do the work below.
 174 ;; (defun help-C-file-name (subr-or-var kind)
 175 ;;   "Return the name of the C file where SUBR-OR-VAR is defined.
 176 ;; KIND should be `var' for a variable or `subr' for a subroutine."
 177 ;;   (symbol-file (if (symbolp subr-or-var) subr-or-var
 178 ;;               (subr-name subr-or-var))
 179 ;;             (if (eq kind 'var) 'defvar 'defun)))
 180 ;;;###autoload
 181 (defun help-C-file-name (subr-or-var kind)
 182   "Return the name of the C file where SUBR-OR-VAR is defined.
 183 KIND should be `var' for a variable or `subr' for a subroutine."
 184   (let ((docbuf (get-buffer-create " *DOC*"))
 185         (name (if (eq 'var kind)
 186                   (concat "V" (symbol-name subr-or-var))
 187                 (concat "F" (subr-name subr-or-var)))))
 188     (with-current-buffer docbuf
 189       (goto-char (point-min))
 190       (if (eobp)
 191           (insert-file-contents-literally
 192            (expand-file-name internal-doc-file-name doc-directory)))
 193       (let ((file (catch 'loop
 194                     (while t
 195                       (let ((pnt (search-forward (concat "\x1f" name "\n"))))
 196                         (re-search-backward "\x1fS\\(.*\\)")
 197                         (let ((file (match-string 1)))
 198                           (if (member file build-files)
 199                               (throw 'loop file)
 200                             (goto-char pnt))))))))
 201         (if (string-match "^ns.*\\(\\.o\\|obj\\)\\'" file)
 202             (setq file (replace-match ".m" t t file 1))
 203           (if (string-match "\\.\\(o\\|obj\\)\\'" file)
 204               (setq file (replace-match ".c" t t file))))
 205         (if (string-match "\\.\\(c\\|m\\)\\'" file)
 206             (concat "src/" file)
 207           file)))))
 208
 209 (defcustom help-downcase-arguments nil
 210   "If non-nil, argument names in *Help* buffers are downcased."
 211   :type 'boolean
 212   :group 'help
 213   :version "23.2")
 214
 215 (defun help-highlight-arg (arg)
 216   "Highlight ARG as an argument name for a *Help* buffer.
 217 Return ARG in face `help-argument-name'; ARG is also downcased
 218 if the variable `help-downcase-arguments' is non-nil."
 219   (propertize (if help-downcase-arguments (downcase arg) arg)
 220               'face 'help-argument-name))
 221
 222 (defun help-do-arg-highlight (doc args)
 223   (with-syntax-table (make-syntax-table emacs-lisp-mode-syntax-table)
 224     (modify-syntax-entry ?\- "w")
 225     (dolist (arg args)
 226       (setq doc (replace-regexp-in-string
 227                  ;; This is heuristic, but covers all common cases
 228                  ;; except ARG1-ARG2
 229                  (concat "\\<"                   ; beginning of word
 230                          "\\(?:[a-z-]*-\\)?"     ; for xxx-ARG
 231                          "\\("
 232                          (regexp-quote arg)
 233                          "\\)"
 234                          "\\(?:es\\|s\\|th\\)?"  ; for ARGth, ARGs
 235                          "\\(?:-[a-z0-9-]+\\)?"  ; for ARG-xxx, ARG-n
 236                          "\\(?:-[{([<`\"].*?\\)?"; for ARG-{x}, (x), <x>, [x], `x'
 237                          "\\>")                  ; end of word
 238                  (help-highlight-arg arg)
 239                  doc t t 1)))
 240     doc))
 241
 242 (defun help-highlight-arguments (usage doc &rest args)
 243   (when (and usage (string-match "^(" usage))
 244     (with-temp-buffer
 245       (insert usage)
 246       (goto-char (point-min))
 247       (let ((case-fold-search nil)
 248             (next (not (or args (looking-at "\\["))))
 249             (opt nil))
 250         ;; Make a list of all arguments
 251         (skip-chars-forward "^ ")
 252         (while next
 253           (or opt (not (looking-at " &")) (setq opt t))
 254           (if (not (re-search-forward " \\([\\[(]*\\)\\([^] &)\.]+\\)" nil t))
 255               (setq next nil)
 256             (setq args (cons (match-string 2) args))
 257             (when (and opt (string= (match-string 1) "("))
 258               ;; A pesky CL-style optional argument with default value,
 259               ;; so let's skip over it
 260               (search-backward "(")
 261               (goto-char (scan-sexps (point) 1)))))
 262         ;; Highlight aguments in the USAGE string
 263         (setq usage (help-do-arg-highlight (buffer-string) args))
 264         ;; Highlight arguments in the DOC string
 265         (setq doc (and doc (help-do-arg-highlight doc args))))))
 266   ;; Return value is like the one from help-split-fundoc, but highlighted
 267   (cons usage doc))
 268
 269 ;; The following function was compiled from the former functions
 270 ;; `describe-simplify-lib-file-name' and `find-source-lisp-file' with
 271 ;; some excerpts from `describe-function-1' and `describe-variable'.
 272 ;; The only additional twists provided are (1) locate the defining file
 273 ;; for autoloaded functions, and (2) give preference to files in the
 274 ;; "install directory" (directories found via `load-path') rather than
 275 ;; to files in the "compile directory" (directories found by searching
 276 ;; the loaddefs.el file).  We autoload it because it's also used by
 277 ;; `describe-face' (instead of `describe-simplify-lib-file-name').
 278
 279 ;;;###autoload
 280 (defun find-lisp-object-file-name (object type)
 281   "Guess the file that defined the Lisp object OBJECT, of type TYPE.
 282 OBJECT should be a symbol associated with a function, variable, or face;
 283   alternatively, it can be a function definition.
 284 If TYPE is `defvar', search for a variable definition.
 285 If TYPE is `defface', search for a face definition.
 286 If TYPE is the value returned by `symbol-function' for a function symbol,
 287  search for a function definition.
 288
 289 The return value is the absolute name of a readable file where OBJECT is
 290 defined.  If several such files exist, preference is given to a file
 291 found via `load-path'.  The return value can also be `C-source', which
 292 means that OBJECT is a function or variable defined in C.  If no
 293 suitable file is found, return nil."
 294   (let* ((autoloaded (eq (car-safe type) 'autoload))
 295          (file-name (or (and autoloaded (nth 1 type))
 296                         (symbol-file
 297                          object (if (memq type (list 'defvar 'defface))
 298                                     type
 299                                   'defun)))))
 300     (cond
 301      (autoloaded
 302       ;; An autoloaded function: Locate the file since `symbol-function'
 303       ;; has only returned a bare string here.
 304       (setq file-name
 305             (locate-file file-name load-path '(".el" ".elc") 'readable)))
 306      ((and (stringp file-name)
 307            (string-match "[.]*loaddefs.el\\'" file-name))
 308       ;; An autoloaded variable or face.  Visit loaddefs.el in a buffer
 309       ;; and try to extract the defining file.  The following form is
 310       ;; from `describe-function-1' and `describe-variable'.
 311       (let ((location
 312              (condition-case nil
 313                  (find-function-search-for-symbol object nil file-name)
 314                (error nil))))
 315         (when (cdr location)
 316           (with-current-buffer (car location)
 317             (goto-char (cdr location))
 318             (when (re-search-backward
 319                    "^;;; Generated autoloads from \\(.*\\)" nil t)
 320               (setq file-name
 321                     (locate-file
 322                      (file-name-sans-extension
 323                       (match-string-no-properties 1))
 324                      load-path '(".el" ".elc") 'readable))))))))
 325
 326     (cond
 327      ((and (not file-name) (subrp type))
 328       ;; A built-in function.  The form is from `describe-function-1'.
 329       (if (get-buffer " *DOC*")
 330           (help-C-file-name type 'subr)
 331         'C-source))
 332      ((and (not file-name) (symbolp object)
 333            (integerp (get object 'variable-documentation)))
 334       ;; A variable defined in C.  The form is from `describe-variable'.
 335       (if (get-buffer " *DOC*")
 336           (help-C-file-name object 'var)
 337         'C-source))
 338      ((not (stringp file-name))
 339       ;; If we don't have a file-name string by now, we lost.
 340       nil)
 341      ;; Now, `file-name' should have become an absolute file name.
 342      ;; For files loaded from ~/.emacs.elc, try ~/.emacs.
 343      ((let (fn)
 344         (and (string-equal file-name
 345                            (expand-file-name ".emacs.elc" "~"))
 346              (file-readable-p (setq fn (expand-file-name ".emacs" "~")))
 347              fn)))
 348      ;; When the Elisp source file can be found in the install
 349      ;; directory, return the name of that file.
 350      ((let ((lib-name
 351              (if (string-match "[.]elc\\'" file-name)
 352                  (substring-no-properties file-name 0 -1)
 353                file-name)))
 354         (or (and (file-readable-p lib-name) lib-name)
 355             ;; The library might be compressed.
 356             (and (file-readable-p (concat lib-name ".gz")) lib-name))))
 357      ((let* ((lib-name (file-name-nondirectory file-name))
 358              ;; The next form is from `describe-simplify-lib-file-name'.
 359              (file-name
 360               ;; Try converting the absolute file name to a library
 361               ;; name, convert that back to a file name and see if we
 362               ;; get the original one.  If so, they are equivalent.
 363               (if (equal file-name (locate-file lib-name load-path '("")))
 364                   (if (string-match "[.]elc\\'" lib-name)
 365                       (substring-no-properties lib-name 0 -1)
 366                     lib-name)
 367                 file-name))
 368              ;; The next three forms are from `find-source-lisp-file'.
 369              (elc-file (locate-file
 370                         (concat file-name
 371                                 (if (string-match "\\.el\\'" file-name)
 372                                     "c"
 373                                   ".elc"))
 374                         load-path nil 'readable))
 375              (str (when elc-file
 376                     (with-temp-buffer
 377                       (insert-file-contents-literally elc-file nil 0 256)
 378                       (buffer-string))))
 379              (src-file (and str
 380                             (string-match ";;; from file \\(.*\\.el\\)" str)
 381                             (match-string 1 str))))
 382         (and src-file (file-readable-p src-file) src-file))))))
 383
 384 (declare-function ad-get-advice-info "advice" (function))
 385
 386 ;;;###autoload
 387 (defun describe-function-1 (function)
 388   (let* ((advised (and (symbolp function) (featurep 'advice)
 389                        (ad-get-advice-info function)))
 390          ;; If the function is advised, use the symbol that has the
 391          ;; real definition, if that symbol is already set up.
 392          (real-function
 393           (or (and advised
 394                    (let ((origname (cdr (assq 'origname advised))))
 395                      (and (fboundp origname) origname)))
 396               function))
 397          ;; Get the real definition.
 398          (def (if (symbolp real-function)
 399                   (symbol-function real-function)
 400                 function))
 401          file-name string
 402          (beg (if (commandp def) "an interactive " "a "))
 403          (pt1 (with-current-buffer (help-buffer) (point)))
 404          errtype)
 405     (setq string
 406           (cond ((or (stringp def) (vectorp def))
 407                  "a keyboard macro")
 408                 ((subrp def)
 409                  (if (eq 'unevalled (cdr (subr-arity def)))
 410                      (concat beg "special form")
 411                    (concat beg "built-in function")))
 412                 ((byte-code-function-p def)
 413                  (concat beg "compiled Lisp function"))
 414                 ((symbolp def)
 415                  (while (and (fboundp def)
 416                              (symbolp (symbol-function def)))
 417                    (setq def (symbol-function def)))
 418                  ;; Handle (defalias 'foo 'bar), where bar is undefined.
 419                  (or (fboundp def) (setq errtype 'alias))
 420                  (format "an alias for `%s'" def))
 421                 ((eq (car-safe def) 'lambda)
 422                  (concat beg "Lisp function"))
 423                 ((eq (car-safe def) 'macro)
 424                  "a Lisp macro")
 425                 ((eq (car-safe def) 'closure)
 426                  (concat beg "Lisp closure"))
 427                 ((eq (car-safe def) 'autoload)
 428                  (format "%s autoloaded %s"
 429                          (if (commandp def) "an interactive" "an")
 430                          (if (eq (nth 4 def) 'keymap) "keymap"
 431                            (if (nth 4 def) "Lisp macro" "Lisp function"))))
 432                 ((keymapp def)
 433                  (let ((is-full nil)
 434                        (elts (cdr-safe def)))
 435                    (while elts
 436                      (if (char-table-p (car-safe elts))
 437                          (setq is-full t
 438                                elts nil))
 439                      (setq elts (cdr-safe elts)))
 440                    (if is-full
 441                        "a full keymap"
 442                      "a sparse keymap")))
 443                 (t "")))
 444     (princ string)
 445     (if (eq errtype 'alias)
 446         (princ ",\nwhich is not defined.  Please make a bug report.")
 447       (with-current-buffer standard-output
 448         (save-excursion
 449           (save-match-data
 450             (when (re-search-backward "alias for `\\([^`']+\\)'" nil t)
 451               (help-xref-button 1 'help-function def)))))
 452
 453       (setq file-name (find-lisp-object-file-name function def))
 454       (when file-name
 455         (princ " in `")
 456         ;; We used to add .el to the file name,
 457         ;; but that's completely wrong when the user used load-file.
 458         (princ (if (eq file-name 'C-source)
 459                    "C source code"
 460                  (file-name-nondirectory file-name)))
 461         (princ "'")
 462         ;; Make a hyperlink to the library.
 463         (with-current-buffer standard-output
 464           (save-excursion
 465             (re-search-backward "`\\([^`']+\\)'" nil t)
 466             (help-xref-button 1 'help-function-def function file-name))))
 467       (princ ".")
 468       (with-current-buffer (help-buffer)
 469         (fill-region-as-paragraph (save-excursion (goto-char pt1) (forward-line 0) (point))
 470                                   (point)))
 471       (terpri)(terpri)
 472       (when (commandp function)
 473         (let ((pt2 (with-current-buffer (help-buffer) (point)))
 474               (remapped (command-remapping function)))
 475           (unless (memq remapped '(ignore undefined))
 476             (let ((keys (where-is-internal
 477                          (or remapped function) overriding-local-map nil nil))
 478                   non-modified-keys)
 479               (if (and (eq function 'self-insert-command)
 480                        (vectorp (car-safe keys))
 481                        (consp (aref (car keys) 0)))
 482                   (princ "It is bound to many ordinary text characters.\n")
 483                 ;; Which non-control non-meta keys run this command?
 484                 (dolist (key keys)
 485                   (if (member (event-modifiers (aref key 0)) '(nil (shift)))
 486                       (push key non-modified-keys)))
 487                 (when remapped
 488                   (princ "It is remapped to `")
 489                   (princ (symbol-name remapped))
 490                   (princ "'"))
 491
 492                 (when keys
 493                   (princ (if remapped ", which is bound to " "It is bound to "))
 494                   ;; If lots of ordinary text characters run this command,
 495                   ;; don't mention them one by one.
 496                   (if (< (length non-modified-keys) 10)
 497                       (princ (mapconcat 'key-description keys ", "))
 498                     (dolist (key non-modified-keys)
 499                       (setq keys (delq key keys)))
 500                     (if keys
 501                         (progn
 502                           (princ (mapconcat 'key-description keys ", "))
 503                           (princ ", and many ordinary text characters"))
 504                       (princ "many ordinary text characters"))))
 505                 (when (or remapped keys non-modified-keys)
 506                   (princ ".")
 507                   (terpri)))))
 508
 509           (with-current-buffer (help-buffer)
 510             (fill-region-as-paragraph pt2 (point))
 511             (unless (looking-back "\n\n")
 512               (terpri)))))
 513       ;; Note that list* etc do not get this property until
 514       ;; cl-hack-byte-compiler runs, after bytecomp is loaded.
 515       (when (and (symbolp function)
 516                  (eq (get function 'byte-compile)
 517                      'cl-byte-compile-compiler-macro))
 518         (princ "This function has a compiler macro")
 519         (let ((lib (get function 'compiler-macro-file)))
 520           (when (stringp lib)
 521             (princ (format " in `%s'" lib))
 522             (with-current-buffer standard-output
 523               (save-excursion
 524                 (re-search-backward "`\\([^`']+\\)'" nil t)
 525                 (help-xref-button 1 'help-function-cmacro function lib)))))
 526         (princ ".\n\n"))
 527       (let* ((advertised (gethash def advertised-signature-table t))
 528              (arglist (if (listp advertised)
 529                           advertised (help-function-arglist def)))
 530              (doc (condition-case err (documentation function)
 531                     (error (format "No Doc! %S" err))))
 532              (usage (help-split-fundoc doc function)))
 533         (with-current-buffer standard-output
 534           ;; If definition is a keymap, skip arglist note.
 535           (unless (keymapp function)
 536             (if usage (setq doc (cdr usage)))
 537             (let* ((use (cond
 538                          ((and usage (not (listp advertised))) (car usage))
 539                          ((listp arglist)
 540                           (format "%S" (help-make-usage function arglist)))
 541                          ((stringp arglist) arglist)
 542                          ;; Maybe the arglist is in the docstring of a symbol
 543                          ;; this one is aliased to.
 544                          ((let ((fun real-function))
 545                             (while (and (symbolp fun)
 546                                         (setq fun (symbol-function fun))
 547                                         (not (setq usage (help-split-fundoc
 548                                                           (documentation fun)
 549                                                           function)))))
 550                             usage)
 551                           (car usage))
 552                          ((or (stringp def)
 553                               (vectorp def))
 554                           (format "\nMacro: %s" (format-kbd-macro def)))
 555                          (t "[Missing arglist.  Please make a bug report.]")))
 556                    (high (help-highlight-arguments use doc)))
 557               (let ((fill-begin (point)))
 558                 (insert (car high) "\n")
 559                 (fill-region fill-begin (point)))
 560               (setq doc (cdr high))))
 561
 562           ;; If this is a derived mode, link to the parent.
 563           (let ((parent-mode (and (symbolp real-function)
 564                                   (get real-function
 565                                        'derived-mode-parent))))
 566             (when parent-mode
 567               (with-current-buffer standard-output
 568                 (insert "\nParent mode: `")
 569                 (let ((beg (point)))
 570                   (insert (format "%s" parent-mode))
 571                   (make-text-button beg (point)
 572                                     'type 'help-function
 573                                     'help-args (list parent-mode))))
 574               (princ "'.\n")))
 575
 576           (let* ((obsolete (and
 577                             ;; function might be a lambda construct.
 578                             (symbolp function)
 579                             (get function 'byte-obsolete-info)))
 580                  (use (car obsolete)))
 581             (when obsolete
 582               (princ "\nThis function is obsolete")
 583               (when (nth 2 obsolete)
 584                 (insert (format " since %s" (nth 2 obsolete))))
 585               (insert (cond ((stringp use) (concat ";\n" use))
 586                             (use (format ";\nuse `%s' instead." use))
 587                             (t "."))
 588                       "\n"))
 589             (insert "\n"
 590                     (or doc "Not documented."))))))))
 591
 592 \f
 593 ;; Variables
 594
 595 ;;;###autoload
 596 (defun variable-at-point (&optional any-symbol)
 597   "Return the bound variable symbol found at or before point.
 598 Return 0 if there is no such symbol.
 599 If ANY-SYMBOL is non-nil, don't insist the symbol be bound."
 600   (with-syntax-table emacs-lisp-mode-syntax-table
 601     (or (condition-case ()
 602             (save-excursion
 603               (skip-chars-forward "'")
 604               (or (not (zerop (skip-syntax-backward "_w")))
 605                   (eq (char-syntax (following-char)) ?w)
 606                   (eq (char-syntax (following-char)) ?_)
 607                   (forward-sexp -1))
 608               (skip-chars-forward "'")
 609               (let ((obj (read (current-buffer))))
 610                 (and (symbolp obj) (boundp obj) obj)))
 611           (error nil))
 612         (let* ((str (find-tag-default))
 613                (sym (if str (intern-soft str))))
 614           (if (and sym (or any-symbol (boundp sym)))
 615               sym
 616             (save-match-data
 617               (when (and str (string-match "\\`\\W*\\(.*?\\)\\W*\\'" str))
 618                 (setq sym (intern-soft (match-string 1 str)))
 619                 (and (or any-symbol (boundp sym)) sym)))))
 620         0)))
 621
 622 (defun describe-variable-custom-version-info (variable)
 623   (let ((custom-version (get variable 'custom-version))
 624         (cpv (get variable 'custom-package-version))
 625         (output nil))
 626     (if custom-version
 627         (setq output
 628               (format "This variable was introduced, or its default value was changed, in\nversion %s of Emacs.\n"
 629                       custom-version))
 630       (when cpv
 631         (let* ((package (car-safe cpv))
 632                (version (if (listp (cdr-safe cpv))
 633                             (car (cdr-safe cpv))
 634                           (cdr-safe cpv)))
 635                (pkg-versions (assq package customize-package-emacs-version-alist))
 636                (emacsv (cdr (assoc version pkg-versions))))
 637           (if (and package version)
 638               (setq output
 639                     (format (concat "This variable was introduced, or its default value was changed, in\nversion %s of the %s package"
 640                                     (if emacsv
 641                                         (format " that is part of Emacs %s" emacsv))
 642                                     ".\n")
 643                             version package))))))
 644     output))
 645
 646 ;;;###autoload
 647 (defun describe-variable (variable &optional buffer frame)
 648   "Display the full documentation of VARIABLE (a symbol).
 649 Returns the documentation as a string, also.
 650 If VARIABLE has a buffer-local value in BUFFER or FRAME
 651 \(default to the current buffer and current frame),
 652 it is displayed along with the global value."
 653   (interactive
 654    (let ((v (variable-at-point))
 655          (enable-recursive-minibuffers t)
 656          val)
 657      (setq val (completing-read (if (symbolp v)
 658                                     (format
 659                                      "Describe variable (default %s): " v)
 660                                   "Describe variable: ")
 661                                 obarray
 662                                 (lambda (vv)
 663                                   (or (get vv 'variable-documentation)
 664                                       (and (boundp vv) (not (keywordp vv)))))
 665                                 t nil nil
 666                                 (if (symbolp v) (symbol-name v))))
 667      (list (if (equal val "")
 668                v (intern val)))))
 669   (let (file-name)
 670     (unless (buffer-live-p buffer) (setq buffer (current-buffer)))
 671     (unless (frame-live-p frame) (setq frame (selected-frame)))
 672     (if (not (symbolp variable))
 673         (message "You did not specify a variable")
 674       (save-excursion
 675         (let ((valvoid (not (with-current-buffer buffer (boundp variable))))
 676               val val-start-pos locus)
 677           ;; Extract the value before setting up the output buffer,
 678           ;; in case `buffer' *is* the output buffer.
 679           (unless valvoid
 680             (with-selected-frame frame
 681               (with-current-buffer buffer
 682                 (setq val (symbol-value variable)
 683                       locus (variable-binding-locus variable)))))
 684           (help-setup-xref (list #'describe-variable variable buffer)
 685                            (called-interactively-p 'interactive))
 686           (with-help-window (help-buffer)
 687             (with-current-buffer buffer
 688               (prin1 variable)
 689               (setq file-name (find-lisp-object-file-name variable 'defvar))
 690
 691               (if file-name
 692                   (progn
 693                     (princ " is a variable defined in `")
 694                     (princ (if (eq file-name 'C-source)
 695                                "C source code"
 696                              (file-name-nondirectory file-name)))
 697                     (princ "'.\n")
 698                     (with-current-buffer standard-output
 699                       (save-excursion
 700                         (re-search-backward "`\\([^`']+\\)'" nil t)
 701                         (help-xref-button 1 'help-variable-def
 702                                           variable file-name)))
 703                     (if valvoid
 704                         (princ "It is void as a variable.")
 705                       (princ "Its ")))
 706                 (if valvoid
 707                     (princ " is void as a variable.")
 708                   (princ "'s "))))
 709             (unless valvoid
 710               (with-current-buffer standard-output
 711                 (setq val-start-pos (point))
 712                 (princ "value is ")
 713                 (let ((from (point)))
 714                   (terpri)
 715                   (pp val)
 716                   (if (< (point) (+ 68 (line-beginning-position 0)))
 717                       (delete-region from (1+ from))
 718                     (delete-region (1- from) from))
 719                   (let* ((sv (get variable 'standard-value))
 720                          (origval (and (consp sv)
 721                                        (condition-case nil
 722                                            (eval (car sv))
 723                                          (error :help-eval-error)))))
 724                     (when (and (consp sv)
 725                                (not (equal origval val))
 726                                (not (equal origval :help-eval-error)))
 727                       (princ "\nOriginal value was \n")
 728                       (setq from (point))
 729                       (pp origval)
 730                       (if (< (point) (+ from 20))
 731                           (delete-region (1- from) from)))))))
 732             (terpri)
 733             (when locus
 734               (cond
 735                ((bufferp locus)
 736                 (princ (format "%socal in buffer %s; "
 737                                (if (get variable 'permanent-local)
 738                                    "Permanently l" "L")
 739                                (buffer-name))))
 740                ((framep locus)
 741                 (princ (format "It is a frame-local variable; ")))
 742                ((terminal-live-p locus)
 743                 (princ (format "It is a terminal-local variable; ")))
 744                (t
 745                 (princ (format "It is local to %S" locus))))
 746               (if (not (default-boundp variable))
 747                   (princ "globally void")
 748                 (let ((val (default-value variable)))
 749                   (with-current-buffer standard-output
 750                     (princ "global value is ")
 751                     (terpri)
 752                     ;; Fixme: pp can take an age if you happen to
 753                     ;; ask for a very large expression.  We should
 754                     ;; probably print it raw once and check it's a
 755                     ;; sensible size before prettyprinting.  -- fx
 756                     (let ((from (point)))
 757                       (pp val)
 758                       ;; See previous comment for this function.
 759                       ;; (help-xref-on-pp from (point))
 760                       (if (< (point) (+ from 20))
 761                           (delete-region (1- from) from))))))
 762               (terpri))
 763
 764             ;; If the value is large, move it to the end.
 765             (with-current-buffer standard-output
 766               (when (> (count-lines (point-min) (point-max)) 10)
 767                 ;; Note that setting the syntax table like below
 768                 ;; makes forward-sexp move over a `'s' at the end
 769                 ;; of a symbol.
 770                 (set-syntax-table emacs-lisp-mode-syntax-table)
 771                 (goto-char val-start-pos)
 772                 ;; The line below previously read as
 773                 ;; (delete-region (point) (progn (end-of-line) (point)))
 774                 ;; which suppressed display of the buffer local value for
 775                 ;; large values.
 776                 (when (looking-at "value is") (replace-match ""))
 777                 (save-excursion
 778                   (insert "\n\nValue:")
 779                   (set (make-local-variable 'help-button-cache)
 780                        (point-marker)))
 781                 (insert "value is shown ")
 782                 (insert-button "below"
 783                                'action help-button-cache
 784                                'follow-link t
 785                                'help-echo "mouse-2, RET: show value")
 786                 (insert ".\n")))
 787             (terpri)
 788
 789             (let* ((alias (condition-case nil
 790                               (indirect-variable variable)
 791                             (error variable)))
 792                    (obsolete (get variable 'byte-obsolete-variable))
 793                    (use (car obsolete))
 794                    (safe-var (get variable 'safe-local-variable))
 795                    (doc (or (documentation-property variable 'variable-documentation)
 796                             (documentation-property alias 'variable-documentation)))
 797                    (extra-line nil))
 798               ;; Add a note for variables that have been make-var-buffer-local.
 799               (when (and (local-variable-if-set-p variable)
 800                          (or (not (local-variable-p variable))
 801                              (with-temp-buffer
 802                                (local-variable-if-set-p variable))))
 803                 (setq extra-line t)
 804                 (princ "  Automatically becomes buffer-local when set in any fashion.\n"))
 805
 806               ;; Mention if it's an alias
 807               (unless (eq alias variable)
 808                 (setq extra-line t)
 809                 (princ (format "  This variable is an alias for `%s'.\n" alias)))
 810
 811               (when obsolete
 812                 (setq extra-line t)
 813                 (princ "  This variable is obsolete")
 814                 (if (nth 2 obsolete)
 815                     (princ (format " since %s" (nth 2 obsolete))))
 816                 (princ (cond ((stringp use) (concat ";\n  " use))
 817                              (use (format ";\n  use `%s' instead." (car obsolete)))
 818                              (t ".")))
 819                 (terpri))
 820
 821               (when (member (cons variable val) file-local-variables-alist)
 822                 (setq extra-line t)
 823                 (if (member (cons variable val) dir-local-variables-alist)
 824                     (let ((file (and (buffer-file-name)
 825                                       (not (file-remote-p (buffer-file-name)))
 826                                       (dir-locals-find-file
 827                                        (buffer-file-name))))
 828                           (type "file"))
 829                       (princ "  This variable is a directory local variable")
 830                       (when file
 831                         (if (consp file) ; result from cache
 832                             ;; If the cache element has an mtime, we
 833                             ;; assume it came from a file.
 834                             (if (nth 2 file)
 835                                 (setq file (expand-file-name
 836                                             dir-locals-file (car file)))
 837                               ;; Otherwise, assume it was set directly.
 838                               (setq type "directory")))
 839                         (princ (format "\n  from the %s \"%s\"" type file)))
 840                       (princ ".\n"))
 841                   (princ "  This variable is a file local variable.\n")))
 842
 843               (when (memq variable ignored-local-variables)
 844                 (setq extra-line t)
 845                 (princ "  This variable is ignored when used as a file local \
 846 variable.\n"))
 847
 848               ;; Can be both risky and safe, eg auto-fill-function.
 849               (when (risky-local-variable-p variable)
 850                 (setq extra-line t)
 851                 (princ "  This variable is potentially risky when used as a \
 852 file local variable.\n")
 853                 (when (assq variable safe-local-variable-values)
 854                   (princ "  However, you have added it to \
 855 `safe-local-variable-values'.\n")))
 856
 857               (when safe-var
 858                 (setq extra-line t)
 859                 (princ "  This variable is safe as a file local variable ")
 860                 (princ "if its value\n  satisfies the predicate ")
 861                 (princ (if (byte-code-function-p safe-var)
 862                            "which is byte-compiled expression.\n"
 863                          (format "`%s'.\n" safe-var))))
 864
 865               (if extra-line (terpri))
 866               (princ "Documentation:\n")
 867               (with-current-buffer standard-output
 868                 (insert (or doc "Not documented as a variable."))))
 869
 870             ;; Make a link to customize if this variable can be customized.
 871             (when (custom-variable-p variable)
 872               (let ((customize-label "customize"))
 873                 (terpri)
 874                 (terpri)
 875                 (princ (concat "You can " customize-label " this variable."))
 876                 (with-current-buffer standard-output
 877                   (save-excursion
 878                     (re-search-backward
 879                      (concat "\\(" customize-label "\\)") nil t)
 880                     (help-xref-button 1 'help-customize-variable variable))))
 881               ;; Note variable's version or package version
 882               (let ((output (describe-variable-custom-version-info variable)))
 883                 (when output
 884                   (terpri)
 885                   (terpri)
 886                   (princ output))))
 887
 888             (with-current-buffer standard-output
 889               ;; Return the text we displayed.
 890               (buffer-string))))))))
 891
 892
 893 ;;;###autoload
 894 (defun describe-syntax (&optional buffer)
 895   "Describe the syntax specifications in the syntax table of BUFFER.
 896 The descriptions are inserted in a help buffer, which is then displayed.
 897 BUFFER defaults to the current buffer."
 898   (interactive)
 899   (setq buffer (or buffer (current-buffer)))
 900   (help-setup-xref (list #'describe-syntax buffer)
 901                    (called-interactively-p 'interactive))
 902   (with-help-window (help-buffer)
 903     (let ((table (with-current-buffer buffer (syntax-table))))
 904       (with-current-buffer standard-output
 905         (describe-vector table 'internal-describe-syntax-value)
 906         (while (setq table (char-table-parent table))
 907           (insert "\nThe parent syntax table is:")
 908           (describe-vector table 'internal-describe-syntax-value))))))
 909
 910 (defun help-describe-category-set (value)
 911   (insert (cond
 912            ((null value) "default")
 913            ((char-table-p value) "deeper char-table ...")
 914            (t (condition-case nil
 915                   (category-set-mnemonics value)
 916                 (error "invalid"))))))
 917
 918 ;;;###autoload
 919 (defun describe-categories (&optional buffer)
 920   "Describe the category specifications in the current category table.
 921 The descriptions are inserted in a buffer, which is then displayed.
 922 If BUFFER is non-nil, then describe BUFFER's category table instead.
 923 BUFFER should be a buffer or a buffer name."
 924   (interactive)
 925   (setq buffer (or buffer (current-buffer)))
 926   (help-setup-xref (list #'describe-categories buffer)
 927                    (called-interactively-p 'interactive))
 928   (with-help-window (help-buffer)
 929     (let* ((table (with-current-buffer buffer (category-table)))
 930            (docs (char-table-extra-slot table 0)))
 931       (if (or (not (vectorp docs)) (/= (length docs) 95))
 932           (error "Invalid first extra slot in this category table\n"))
 933       (with-current-buffer standard-output
 934         (insert "Legend of category mnemonics (see the tail for the longer description)\n")
 935         (let ((pos (point)) (items 0) lines n)
 936           (dotimes (i 95)
 937             (if (aref docs i) (setq items (1+ items))))
 938           (setq lines (1+ (/ (1- items) 4)))
 939           (setq n 0)
 940           (dotimes (i 95)
 941             (let ((elt (aref docs i)))
 942               (when elt
 943                 (string-match ".*" elt)
 944                 (setq elt (match-string 0 elt))
 945                 (if (>= (length elt) 17)
 946                     (setq elt (concat (substring elt 0 14) "...")))
 947                 (if (< (point) (point-max))
 948                     (move-to-column (* 20 (/ n lines)) t))
 949                 (insert (+ i ?\s) ?: elt)
 950                 (if (< (point) (point-max))
 951                     (forward-line 1)
 952                   (insert "\n"))
 953                 (setq n (1+ n))
 954                 (if (= (% n lines) 0)
 955                     (goto-char pos))))))
 956         (goto-char (point-max))
 957         (insert "\n"
 958                 "character(s)\tcategory mnemonics\n"
 959                 "------------\t------------------")
 960         (describe-vector table 'help-describe-category-set)
 961         (insert "Legend of category mnemonics:\n")
 962         (dotimes (i 95)
 963           (let ((elt (aref docs i)))
 964             (when elt
 965               (if (string-match "\n" elt)
 966                   (setq elt (substring elt (match-end 0))))
 967               (insert (+ i ?\s) ": " elt "\n"))))
 968         (while (setq table (char-table-parent table))
 969           (insert "\nThe parent category table is:")
 970           (describe-vector table 'help-describe-category-set))))))
 971
 972 \f
 973 ;;; Replacements for old lib-src/ programs.  Don't seem especially useful.
 974
 975 ;; Replaces lib-src/digest-doc.c.
 976 ;;;###autoload
 977 (defun doc-file-to-man (file)
 978   "Produce an nroff buffer containing the doc-strings from the DOC file."
 979   (interactive (list (read-file-name "Name of DOC file: " doc-directory
 980                                      internal-doc-file-name t)))
 981   (or (file-readable-p file)
 982       (error "Cannot read file `%s'" file))
 983   (pop-to-buffer (generate-new-buffer "*man-doc*"))
 984   (setq buffer-undo-list t)
 985   (insert ".TH \"Command Summary for GNU Emacs\"\n"
 986           ".AU Richard M. Stallman\n")
 987   (insert-file-contents file)
 988   (let (notfirst)
 989     (while (search-forward "\x1f" nil 'move)
 990       (if (looking-at "S")
 991           (delete-region (1- (point)) (line-end-position))
 992         (delete-char -1)
 993         (if notfirst
 994             (insert "\n.DE\n")
 995           (setq notfirst t))
 996         (insert "\n.SH ")
 997         (insert (if (looking-at "F") "Function " "Variable "))
 998         (delete-char 1)
 999         (forward-line 1)
1000         (insert ".DS L\n"))))
1001   (insert "\n.DE\n")
1002   (setq buffer-undo-list nil)
1003   (nroff-mode))
1004
1005 ;; Replaces lib-src/sorted-doc.c.
1006 ;;;###autoload
1007 (defun doc-file-to-info (file)
1008   "Produce a texinfo buffer with sorted doc-strings from the DOC file."
1009   (interactive (list (read-file-name "Name of DOC file: " doc-directory
1010                                      internal-doc-file-name t)))
1011   (or (file-readable-p file)
1012       (error "Cannot read file `%s'" file))
1013   (let ((i 0) type name doc alist)
1014     (with-temp-buffer
1015       (insert-file-contents file)
1016       ;; The characters "@{}" need special treatment.
1017       (while (re-search-forward "[@{}]" nil t)
1018         (backward-char)
1019         (insert "@")
1020         (forward-char 1))
1021       (goto-char (point-min))
1022       (while (search-forward "\x1f" nil t)
1023         (unless (looking-at "S")
1024           (setq type (char-after)
1025                 name (buffer-substring (1+ (point)) (line-end-position))
1026                 doc (buffer-substring (line-beginning-position 2)
1027                                       (if (search-forward  "\x1f" nil 'move)
1028                                           (1- (point))
1029                                         (point)))
1030                 alist (cons (list name type doc) alist))
1031           (backward-char 1))))
1032     (pop-to-buffer (generate-new-buffer "*info-doc*"))
1033     (setq buffer-undo-list t)
1034     ;; Write the output header.
1035     (insert "\\input texinfo  @c -*-texinfo-*-\n"
1036             "@setfilename emacsdoc.info\n"
1037             "@settitle Command Summary for GNU Emacs\n"
1038             "@finalout\n"
1039             "\n@node Top\n"
1040             "@unnumbered Command Summary for GNU Emacs\n\n"
1041             "@table @asis\n\n"
1042             "@iftex\n"
1043             "@global@let@ITEM@item\n"
1044             "@def@item{@filbreak@vskip5pt@ITEM}\n"
1045             "@font@tensy cmsy10 scaled @magstephalf\n"
1046             "@font@teni cmmi10 scaled @magstephalf\n"
1047             "@def\\{{@tensy@char110}}\n" ; this backslash goes with cmr10
1048             "@def|{{@tensy@char106}}\n"
1049             "@def@{{{@tensy@char102}}\n"
1050             "@def@}{{@tensy@char103}}\n"
1051             "@def<{{@teni@char62}}\n"
1052             "@def>{{@teni@char60}}\n"
1053             "@chardef@@64\n"
1054             "@catcode43=12\n"
1055             "@tableindent-0.2in\n"
1056             "@end iftex\n")
1057     ;; Sort the array by name; within each name, by type (functions first).
1058     (setq alist (sort alist (lambda (e1 e2)
1059                               (if (string-equal (car e1) (car e2))
1060                                   (<= (cadr e1) (cadr e2))
1061                                 (string-lessp (car e1) (car e2))))))
1062     ;; Print each function.
1063     (dolist (e alist)
1064       (insert "\n@item "
1065               (if (char-equal (cadr e) ?\F) "Function" "Variable")
1066               " @code{" (car e) "}\n@display\n"
1067               (nth 2 e)
1068               "\n@end display\n")
1069       ;; Try to avoid a save size overflow in the TeX output routine.
1070       (if (zerop (setq i (% (1+ i) 100)))
1071           (insert "\n@end table\n@table @asis\n")))
1072     (insert "@end table\n"
1073             "@bye\n")
1074     (setq buffer-undo-list nil)
1075     (texinfo-mode)))
1076
1077 (provide 'help-fns)
1078
1079 ;;; help-fns.el ends here