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