lisp/help-fns.el

   1 ;;; help-fns.el --- Complex help functions -*- lexical-binding: t -*-
   2
   3 ;; Copyright (C) 1985-1986, 1993-1994, 1998-2014 Free Software
   4 ;; Foundation, Inc.
   5
   6 ;; Maintainer: emacs-devel@gnu.org
   7 ;; Keywords: help, internal
   8 ;; Package: emacs
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; GNU Emacs is free software: you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation, either version 3 of the License, or
  15 ;; (at your option) any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  24
  25 ;;; Commentary:
  26
  27 ;; This file contains those help commands which are complicated, and
  28 ;; which may not be used in every session.  For example
  29 ;; `describe-function' will probably be heavily used when doing elisp
  30 ;; programming, but not if just editing C files.  Simpler help commands
  31 ;; are in help.el
  32
  33 ;;; Code:
  34
  35 (defvar help-fns-describe-function-functions nil
  36   "List of functions to run in help buffer in `describe-function'.
  37 Those functions will be run after the header line and argument
  38 list was inserted, and before the documentation will be inserted.
  39 The functions will receive the function name as argument.")
  40
  41 ;; Functions
  42
  43 ;;;###autoload
  44 (defun describe-function (function)
  45   "Display the full documentation of FUNCTION (a symbol)."
  46   (interactive
  47    (let ((fn (function-called-at-point))
  48          (enable-recursive-minibuffers t)
  49          val)
  50      (setq val (completing-read (if fn
  51                                     (format "Describe function (default %s): " fn)
  52                                   "Describe function: ")
  53                                 obarray 'fboundp t nil nil
  54                                 (and fn (symbol-name fn))))
  55      (list (if (equal val "")
  56                fn (intern val)))))
  57   (if (null function)
  58       (message "You didn't specify a function")
  59     (help-setup-xref (list #'describe-function function)
  60                      (called-interactively-p 'interactive))
  61     (save-excursion
  62       (with-help-window (help-buffer)
  63         (prin1 function)
  64         ;; Use " is " instead of a colon so that
  65         ;; it is easier to get out the function name using forward-sexp.
  66         (princ " is ")
  67         (describe-function-1 function)
  68         (with-current-buffer standard-output
  69           ;; Return the text we displayed.
  70           (buffer-string))))))
  71
  72
  73 ;; Could be this, if we make symbol-file do the work below.
  74 ;; (defun help-C-file-name (subr-or-var kind)
  75 ;;   "Return the name of the C file where SUBR-OR-VAR is defined.
  76 ;; KIND should be `var' for a variable or `subr' for a subroutine."
  77 ;;   (symbol-file (if (symbolp subr-or-var) subr-or-var
  78 ;;               (subr-name subr-or-var))
  79 ;;             (if (eq kind 'var) 'defvar 'defun)))
  80 ;;;###autoload
  81 (defun help-C-file-name (subr-or-var kind)
  82   "Return the name of the C file where SUBR-OR-VAR is defined.
  83 KIND should be `var' for a variable or `subr' for a subroutine."
  84   (let ((docbuf (get-buffer-create " *DOC*"))
  85         (name (if (eq 'var kind)
  86                   (concat "V" (symbol-name subr-or-var))
  87                 (concat "F" (subr-name (advice--cd*r subr-or-var))))))
  88     (with-current-buffer docbuf
  89       (goto-char (point-min))
  90       (if (eobp)
  91           (insert-file-contents-literally
  92            (expand-file-name internal-doc-file-name doc-directory)))
  93       (let ((file (catch 'loop
  94                     (while t
  95                       (let ((pnt (search-forward (concat "\x1f" name "\n"))))
  96                         (re-search-backward "\x1fS\\(.*\\)")
  97                         (let ((file (match-string 1)))
  98                           (if (member file build-files)
  99                               (throw 'loop file)
 100                             (goto-char pnt))))))))
 101         (if (string-match "^ns.*\\(\\.o\\|obj\\)\\'" file)
 102             (setq file (replace-match ".m" t t file 1))
 103           (if (string-match "\\.\\(o\\|obj\\)\\'" file)
 104               (setq file (replace-match ".c" t t file))))
 105         (if (string-match "\\.\\(c\\|m\\)\\'" file)
 106             (concat "src/" file)
 107           file)))))
 108
 109 (defcustom help-downcase-arguments nil
 110   "If non-nil, argument names in *Help* buffers are downcased."
 111   :type 'boolean
 112   :group 'help
 113   :version "23.2")
 114
 115 (defun help-highlight-arg (arg)
 116   "Highlight ARG as an argument name for a *Help* buffer.
 117 Return ARG in face `help-argument-name'; ARG is also downcased
 118 if the variable `help-downcase-arguments' is non-nil."
 119   (propertize (if help-downcase-arguments (downcase arg) arg)
 120               'face 'help-argument-name))
 121
 122 (defun help-do-arg-highlight (doc args)
 123   (with-syntax-table (make-syntax-table emacs-lisp-mode-syntax-table)
 124     (modify-syntax-entry ?\- "w")
 125     (dolist (arg args)
 126       (setq doc (replace-regexp-in-string
 127                  ;; This is heuristic, but covers all common cases
 128                  ;; except ARG1-ARG2
 129                  (concat "\\<"                   ; beginning of word
 130                          "\\(?:[a-z-]*-\\)?"     ; for xxx-ARG
 131                          "\\("
 132                          (regexp-quote arg)
 133                          "\\)"
 134                          "\\(?:es\\|s\\|th\\)?"  ; for ARGth, ARGs
 135                          "\\(?:-[a-z0-9-]+\\)?"  ; for ARG-xxx, ARG-n
 136                          "\\(?:-[{([<`\"].*?\\)?"; for ARG-{x}, (x), <x>, [x], `x'
 137                          "\\>")                  ; end of word
 138                  (help-highlight-arg arg)
 139                  doc t t 1)))
 140     doc))
 141
 142 (defun help-highlight-arguments (usage doc &rest args)
 143   (when (and usage (string-match "^(" usage))
 144     (with-temp-buffer
 145       (insert usage)
 146       (goto-char (point-min))
 147       (let ((case-fold-search nil)
 148             (next (not (or args (looking-at "\\["))))
 149             (opt nil))
 150         ;; Make a list of all arguments
 151         (skip-chars-forward "^ ")
 152         (while next
 153           (or opt (not (looking-at " &")) (setq opt t))
 154           (if (not (re-search-forward " \\([\\[(]*\\)\\([^] &)\.]+\\)" nil t))
 155               (setq next nil)
 156             (setq args (cons (match-string 2) args))
 157             (when (and opt (string= (match-string 1) "("))
 158               ;; A pesky CL-style optional argument with default value,
 159               ;; so let's skip over it
 160               (search-backward "(")
 161               (goto-char (scan-sexps (point) 1)))))
 162         ;; Highlight arguments in the USAGE string
 163         (setq usage (help-do-arg-highlight (buffer-string) args))
 164         ;; Highlight arguments in the DOC string
 165         (setq doc (and doc (help-do-arg-highlight doc args))))))
 166   ;; Return value is like the one from help-split-fundoc, but highlighted
 167   (cons usage doc))
 168
 169 ;; The following function was compiled from the former functions
 170 ;; `describe-simplify-lib-file-name' and `find-source-lisp-file' with
 171 ;; some excerpts from `describe-function-1' and `describe-variable'.
 172 ;; The only additional twists provided are (1) locate the defining file
 173 ;; for autoloaded functions, and (2) give preference to files in the
 174 ;; "install directory" (directories found via `load-path') rather than
 175 ;; to files in the "compile directory" (directories found by searching
 176 ;; the loaddefs.el file).  We autoload it because it's also used by
 177 ;; `describe-face' (instead of `describe-simplify-lib-file-name').
 178
 179 ;;;###autoload
 180 (defun find-lisp-object-file-name (object type)
 181   "Guess the file that defined the Lisp object OBJECT, of type TYPE.
 182 OBJECT should be a symbol associated with a function, variable, or face;
 183   alternatively, it can be a function definition.
 184 If TYPE is `defvar', search for a variable definition.
 185 If TYPE is `defface', search for a face definition.
 186 If TYPE is the value returned by `symbol-function' for a function symbol,
 187  search for a function definition.
 188
 189 The return value is the absolute name of a readable file where OBJECT is
 190 defined.  If several such files exist, preference is given to a file
 191 found via `load-path'.  The return value can also be `C-source', which
 192 means that OBJECT is a function or variable defined in C.  If no
 193 suitable file is found, return nil."
 194   (let* ((autoloaded (autoloadp type))
 195          (file-name (or (and autoloaded (nth 1 type))
 196                         (symbol-file
 197                          object (if (memq type (list 'defvar 'defface))
 198                                     type
 199                                   'defun)))))
 200     (cond
 201      (autoloaded
 202       ;; An autoloaded function: Locate the file since `symbol-function'
 203       ;; has only returned a bare string here.
 204       (setq file-name
 205             (locate-file file-name load-path '(".el" ".elc") 'readable)))
 206      ((and (stringp file-name)
 207            (string-match "[.]*loaddefs.el\\'" file-name))
 208       ;; An autoloaded variable or face.  Visit loaddefs.el in a buffer
 209       ;; and try to extract the defining file.  The following form is
 210       ;; from `describe-function-1' and `describe-variable'.
 211       (let ((location
 212              (condition-case nil
 213                  (find-function-search-for-symbol object nil file-name)
 214                (error nil))))
 215         (when (cdr location)
 216           (with-current-buffer (car location)
 217             (goto-char (cdr location))
 218             (when (re-search-backward
 219                    "^;;; Generated autoloads from \\(.*\\)" nil t)
 220               (setq file-name
 221                     (locate-file
 222                      (file-name-sans-extension
 223                       (match-string-no-properties 1))
 224                      load-path '(".el" ".elc") 'readable))))))))
 225
 226     (cond
 227      ((and (not file-name) (subrp type))
 228       ;; A built-in function.  The form is from `describe-function-1'.
 229       (if (get-buffer " *DOC*")
 230           (help-C-file-name type 'subr)
 231         'C-source))
 232      ((and (not file-name) (symbolp object)
 233            (integerp (get object 'variable-documentation)))
 234       ;; A variable defined in C.  The form is from `describe-variable'.
 235       (if (get-buffer " *DOC*")
 236           (help-C-file-name object 'var)
 237         'C-source))
 238      ((not (stringp file-name))
 239       ;; If we don't have a file-name string by now, we lost.
 240       nil)
 241      ;; Now, `file-name' should have become an absolute file name.
 242      ;; For files loaded from ~/.foo.elc, try ~/.foo.
 243      ;; This applies to config files like ~/.emacs,
 244      ;; which people sometimes compile.
 245      ((let (fn)
 246         (and (string-match "\\`\\..*\\.elc\\'"
 247                            (file-name-nondirectory file-name))
 248              (string-equal (file-name-directory file-name)
 249                            (file-name-as-directory (expand-file-name "~")))
 250              (file-readable-p (setq fn (file-name-sans-extension file-name)))
 251              fn)))
 252      ;; When the Elisp source file can be found in the install
 253      ;; directory, return the name of that file.
 254      ((let ((lib-name
 255              (if (string-match "[.]elc\\'" file-name)
 256                  (substring-no-properties file-name 0 -1)
 257                file-name)))
 258         (or (and (file-readable-p lib-name) lib-name)
 259             ;; The library might be compressed.
 260             (and (file-readable-p (concat lib-name ".gz")) lib-name))))
 261      ((let* ((lib-name (file-name-nondirectory file-name))
 262              ;; The next form is from `describe-simplify-lib-file-name'.
 263              (file-name
 264               ;; Try converting the absolute file name to a library
 265               ;; name, convert that back to a file name and see if we
 266               ;; get the original one.  If so, they are equivalent.
 267               (if (equal file-name (locate-file lib-name load-path '("")))
 268                   (if (string-match "[.]elc\\'" lib-name)
 269                       (substring-no-properties lib-name 0 -1)
 270                     lib-name)
 271                 file-name))
 272              ;; The next three forms are from `find-source-lisp-file'.
 273              (elc-file (locate-file
 274                         (concat file-name
 275                                 (if (string-match "\\.el\\'" file-name)
 276                                     "c"
 277                                   ".elc"))
 278                         load-path nil 'readable))
 279              (str (when elc-file
 280                     (with-temp-buffer
 281                       (insert-file-contents-literally elc-file nil 0 256)
 282                       (buffer-string))))
 283              (src-file (and str
 284                             (string-match ";;; from file \\(.*\\.el\\)" str)
 285                             (match-string 1 str))))
 286         (and src-file (file-readable-p src-file) src-file))))))
 287
 288 (defun help-fns--key-bindings (function)
 289   (when (commandp function)
 290     (let ((pt2 (with-current-buffer standard-output (point)))
 291           (remapped (command-remapping function)))
 292       (unless (memq remapped '(ignore undefined))
 293         (let ((keys (where-is-internal
 294                      (or remapped function) overriding-local-map nil nil))
 295               non-modified-keys)
 296           (if (and (eq function 'self-insert-command)
 297                    (vectorp (car-safe keys))
 298                    (consp (aref (car keys) 0)))
 299               (princ "It is bound to many ordinary text characters.\n")
 300             ;; Which non-control non-meta keys run this command?
 301             (dolist (key keys)
 302               (if (member (event-modifiers (aref key 0)) '(nil (shift)))
 303                   (push key non-modified-keys)))
 304             (when remapped
 305               (princ "Its keys are remapped to ")
 306               (princ (if (symbolp remapped)
 307                          (concat "`" (symbol-name remapped) "'")
 308                        "an anonymous command"))
 309               (princ ".\n"))
 310
 311             (when keys
 312               (princ (if remapped
 313                          "Without this remapping, it would be bound to "
 314                        "It is bound to "))
 315               ;; If lots of ordinary text characters run this command,
 316               ;; don't mention them one by one.
 317               (if (< (length non-modified-keys) 10)
 318                   (princ (mapconcat 'key-description keys ", "))
 319                 (dolist (key non-modified-keys)
 320                   (setq keys (delq key keys)))
 321                 (if keys
 322                     (progn
 323                       (princ (mapconcat 'key-description keys ", "))
 324                       (princ ", and many ordinary text characters"))
 325                   (princ "many ordinary text characters"))))
 326             (when (or remapped keys non-modified-keys)
 327               (princ ".")
 328               (terpri)))))
 329
 330       (with-current-buffer standard-output
 331         (fill-region-as-paragraph pt2 (point))
 332         (unless (looking-back "\n\n")
 333           (terpri))))))
 334
 335 (defun help-fns--compiler-macro (function)
 336   (let ((handler (function-get function 'compiler-macro)))
 337     (when handler
 338       (insert "\nThis function has a compiler macro")
 339       (if (symbolp handler)
 340           (progn
 341             (insert (format " `%s'" handler))
 342             (save-excursion
 343               (re-search-backward "`\\([^`']+\\)'" nil t)
 344               (help-xref-button 1 'help-function handler)))
 345         ;; FIXME: Obsolete since 24.4.
 346         (let ((lib (get function 'compiler-macro-file)))
 347           (when (stringp lib)
 348             (insert (format " in `%s'" lib))
 349             (save-excursion
 350               (re-search-backward "`\\([^`']+\\)'" nil t)
 351               (help-xref-button 1 'help-function-cmacro function lib)))))
 352       (insert ".\n"))))
 353
 354 (defun help-fns--signature (function doc real-def real-function)
 355   (unless (keymapp function)    ; If definition is a keymap, skip arglist note.
 356     (let* ((advertised (gethash real-def advertised-signature-table t))
 357            (arglist (if (listp advertised)
 358                         advertised (help-function-arglist real-def)))
 359            (usage (help-split-fundoc doc function)))
 360       (if usage (setq doc (cdr usage)))
 361       (let* ((use (cond
 362                    ((and usage (not (listp advertised))) (car usage))
 363                    ((listp arglist)
 364                     (format "%S" (help-make-usage function arglist)))
 365                    ((stringp arglist) arglist)
 366                    ;; Maybe the arglist is in the docstring of a symbol
 367                    ;; this one is aliased to.
 368                    ((let ((fun real-function))
 369                       (while (and (symbolp fun)
 370                                   (setq fun (symbol-function fun))
 371                                   (not (setq usage (help-split-fundoc
 372                                                     (documentation fun)
 373                                                     function)))))
 374                       usage)
 375                     (car usage))
 376                    ((or (stringp real-def)
 377                         (vectorp real-def))
 378                     (format "\nMacro: %s" (format-kbd-macro real-def)))
 379                    (t "[Missing arglist.  Please make a bug report.]")))
 380              (high (help-highlight-arguments use doc)))
 381         (let ((fill-begin (point)))
 382           (insert (car high) "\n")
 383           (fill-region fill-begin (point)))
 384         (cdr high)))))
 385
 386 (defun help-fns--parent-mode (function)
 387   ;; If this is a derived mode, link to the parent.
 388   (let ((parent-mode (and (symbolp function)
 389                           (get function
 390                                'derived-mode-parent))))
 391     (when parent-mode
 392       (insert "\nParent mode: `")
 393       (let ((beg (point)))
 394         (insert (format "%s" parent-mode))
 395         (make-text-button beg (point)
 396                           'type 'help-function
 397                           'help-args (list parent-mode)))
 398       (insert "'.\n"))))
 399
 400 (defun help-fns--obsolete (function)
 401   ;; Ignore lambda constructs, keyboard macros, etc.
 402   (let* ((obsolete (and (symbolp function)
 403                         (get function 'byte-obsolete-info)))
 404          (use (car obsolete)))
 405     (when obsolete
 406       (insert "\nThis "
 407               (if (eq (car-safe (symbol-function function)) 'macro)
 408                   "macro"
 409                 "function")
 410               " is obsolete")
 411       (when (nth 2 obsolete)
 412         (insert (format " since %s" (nth 2 obsolete))))
 413       (insert (cond ((stringp use) (concat ";\n" use))
 414                     (use (format ";\nuse `%s' instead." use))
 415                     (t "."))
 416               "\n"))))
 417
 418 ;; We could use `symbol-file' but this is a wee bit more efficient.
 419 (defun help-fns--autoloaded-p (function file)
 420   "Return non-nil if FUNCTION has previously been autoloaded.
 421 FILE is the file where FUNCTION was probably defined."
 422   (let* ((file (file-name-sans-extension (file-truename file)))
 423          (load-hist load-history)
 424          (target (cons t function))
 425          found)
 426     (while (and load-hist (not found))
 427       (and (caar load-hist)
 428            (equal (file-name-sans-extension (caar load-hist)) file)
 429            (setq found (member target (cdar load-hist))))
 430       (setq load-hist (cdr load-hist)))
 431     found))
 432
 433 ;;;###autoload
 434 (defun describe-function-1 (function)
 435   (let* ((advised (and (symbolp function)
 436                        (featurep 'nadvice)
 437                        (advice--p (advice--symbol-function function))))
 438          ;; If the function is advised, use the symbol that has the
 439          ;; real definition, if that symbol is already set up.
 440          (real-function
 441           (or (and advised
 442                    (advice--cd*r (advice--symbol-function function)))
 443               function))
 444          ;; Get the real definition.
 445          (def (if (symbolp real-function)
 446                   (symbol-function real-function)
 447                 real-function))
 448          (aliased (or (symbolp def)
 449                       ;; Advised & aliased function.
 450                       (and advised (symbolp real-function))))
 451          (real-def (cond
 452                     (aliased (let ((f real-function))
 453                                (while (and (fboundp f)
 454                                            (symbolp (symbol-function f)))
 455                                  (setq f (symbol-function f)))
 456                                f))
 457                     ((subrp def) (intern (subr-name def)))
 458                     (t def)))
 459          (file-name (find-lisp-object-file-name function def))
 460          (pt1 (with-current-buffer (help-buffer) (point)))
 461          (beg (if (and (or (byte-code-function-p def)
 462                            (keymapp def)
 463                            (memq (car-safe def) '(macro lambda closure)))
 464                        file-name
 465                        (help-fns--autoloaded-p function file-name))
 466                   (if (commandp def)
 467                       "an interactive autoloaded "
 468                     "an autoloaded ")
 469                 (if (commandp def) "an interactive " "a "))))
 470
 471     ;; Print what kind of function-like object FUNCTION is.
 472     (princ (cond ((or (stringp def) (vectorp def))
 473                   "a keyboard macro")
 474                  ((subrp def)
 475                   (if (eq 'unevalled (cdr (subr-arity def)))
 476                       (concat beg "special form")
 477                     (concat beg "built-in function")))
 478                  ;; Aliases are Lisp functions, so we need to check
 479                  ;; aliases before functions.
 480                  (aliased
 481                   (format "an alias for `%s'" real-def))
 482                  ((or (eq (car-safe def) 'macro)
 483                       ;; For advised macros, def is a lambda
 484                       ;; expression or a byte-code-function-p, so we
 485                       ;; need to check macros before functions.
 486                       (macrop function))
 487                   (concat beg "Lisp macro"))
 488                  ((byte-code-function-p def)
 489                   (concat beg "compiled Lisp function"))
 490                  ((eq (car-safe def) 'lambda)
 491                   (concat beg "Lisp function"))
 492                  ((eq (car-safe def) 'closure)
 493                   (concat beg "Lisp closure"))
 494                  ((autoloadp def)
 495                   (format "%s autoloaded %s"
 496                           (if (commandp def) "an interactive" "an")
 497                           (if (eq (nth 4 def) 'keymap) "keymap"
 498                             (if (nth 4 def) "Lisp macro" "Lisp function"))))
 499                  ((keymapp def)
 500                   (let ((is-full nil)
 501                         (elts (cdr-safe def)))
 502                     (while elts
 503                       (if (char-table-p (car-safe elts))
 504                           (setq is-full t
 505                                 elts nil))
 506                       (setq elts (cdr-safe elts)))
 507                     (concat beg (if is-full "keymap" "sparse keymap"))))
 508                  (t "")))
 509
 510     (if (and aliased (not (fboundp real-def)))
 511         (princ ",\nwhich is not defined.  Please make a bug report.")
 512       (with-current-buffer standard-output
 513         (save-excursion
 514           (save-match-data
 515             (when (re-search-backward "alias for `\\([^`']+\\)'" nil t)
 516               (help-xref-button 1 'help-function real-def)))))
 517
 518       (when file-name
 519         (princ " in `")
 520         ;; We used to add .el to the file name,
 521         ;; but that's completely wrong when the user used load-file.
 522         (princ (if (eq file-name 'C-source)
 523                    "C source code"
 524                  (file-name-nondirectory file-name)))
 525         (princ "'")
 526         ;; Make a hyperlink to the library.
 527         (with-current-buffer standard-output
 528           (save-excursion
 529             (re-search-backward "`\\([^`']+\\)'" nil t)
 530             (help-xref-button 1 'help-function-def function file-name))))
 531       (princ ".")
 532       (with-current-buffer (help-buffer)
 533         (fill-region-as-paragraph (save-excursion (goto-char pt1) (forward-line 0) (point))
 534                                   (point)))
 535       (terpri)(terpri)
 536
 537       (let* ((doc-raw (documentation function t))
 538              ;; If the function is autoloaded, and its docstring has
 539              ;; key substitution constructs, load the library.
 540              (doc (progn
 541                     (and (autoloadp real-def) doc-raw
 542                          help-enable-auto-load
 543                          (string-match "\\([^\\]=\\|[^=]\\|\\`\\)\\\\[[{<]"
 544                                        doc-raw)
 545                          (load (cadr real-def) t))
 546                     (substitute-command-keys doc-raw))))
 547
 548         (help-fns--key-bindings function)
 549         (with-current-buffer standard-output
 550           (setq doc (help-fns--signature function doc real-def real-function))
 551           (run-hook-with-args 'help-fns-describe-function-functions function)
 552           (insert "\n"
 553                   (or doc "Not documented.")))))))
 554
 555 ;; Add defaults to `help-fns-describe-function-functions'.
 556 (add-hook 'help-fns-describe-function-functions #'help-fns--obsolete)
 557 (add-hook 'help-fns-describe-function-functions #'help-fns--parent-mode)
 558 (add-hook 'help-fns-describe-function-functions #'help-fns--compiler-macro)
 559
 560 \f
 561 ;; Variables
 562
 563 ;;;###autoload
 564 (defun variable-at-point (&optional any-symbol)
 565   "Return the bound variable symbol found at or before point.
 566 Return 0 if there is no such symbol.
 567 If ANY-SYMBOL is non-nil, don't insist the symbol be bound."
 568   (with-syntax-table emacs-lisp-mode-syntax-table
 569     (or (condition-case ()
 570             (save-excursion
 571               (skip-chars-forward "'")
 572               (or (not (zerop (skip-syntax-backward "_w")))
 573                   (eq (char-syntax (following-char)) ?w)
 574                   (eq (char-syntax (following-char)) ?_)
 575                   (forward-sexp -1))
 576               (skip-chars-forward "'")
 577               (let ((obj (read (current-buffer))))
 578                 (and (symbolp obj) (boundp obj) obj)))
 579           (error nil))
 580         (let* ((str (find-tag-default))
 581                (sym (if str (intern-soft str))))
 582           (if (and sym (or any-symbol (boundp sym)))
 583               sym
 584             (save-match-data
 585               (when (and str (string-match "\\`\\W*\\(.*?\\)\\W*\\'" str))
 586                 (setq sym (intern-soft (match-string 1 str)))
 587                 (and (or any-symbol (boundp sym)) sym)))))
 588         0)))
 589
 590 (defun describe-variable-custom-version-info (variable)
 591   (let ((custom-version (get variable 'custom-version))
 592         (cpv (get variable 'custom-package-version))
 593         (output nil))
 594     (if custom-version
 595         (setq output
 596               (format "This variable was introduced, or its default value was changed, in\nversion %s of Emacs.\n"
 597                       custom-version))
 598       (when cpv
 599         (let* ((package (car-safe cpv))
 600                (version (if (listp (cdr-safe cpv))
 601                             (car (cdr-safe cpv))
 602                           (cdr-safe cpv)))
 603                (pkg-versions (assq package customize-package-emacs-version-alist))
 604                (emacsv (cdr (assoc version pkg-versions))))
 605           (if (and package version)
 606               (setq output
 607                     (format (concat "This variable was introduced, or its default value was changed, in\nversion %s of the %s package"
 608                                     (if emacsv
 609                                         (format " that is part of Emacs %s" emacsv))
 610                                     ".\n")
 611                             version package))))))
 612     output))
 613
 614 ;;;###autoload
 615 (defun describe-variable (variable &optional buffer frame)
 616   "Display the full documentation of VARIABLE (a symbol).
 617 Returns the documentation as a string, also.
 618 If VARIABLE has a buffer-local value in BUFFER or FRAME
 619 \(default to the current buffer and current frame),
 620 it is displayed along with the global value."
 621   (interactive
 622    (let ((v (variable-at-point))
 623          (enable-recursive-minibuffers t)
 624          val)
 625      (setq val (completing-read (if (symbolp v)
 626                                     (format
 627                                      "Describe variable (default %s): " v)
 628                                   "Describe variable: ")
 629                                 obarray
 630                                 (lambda (vv)
 631                                   (or (get vv 'variable-documentation)
 632                                       (and (boundp vv) (not (keywordp vv)))))
 633                                 t nil nil
 634                                 (if (symbolp v) (symbol-name v))))
 635      (list (if (equal val "")
 636                v (intern val)))))
 637   (let (file-name)
 638     (unless (buffer-live-p buffer) (setq buffer (current-buffer)))
 639     (unless (frame-live-p frame) (setq frame (selected-frame)))
 640     (if (not (symbolp variable))
 641         (message "You did not specify a variable")
 642       (save-excursion
 643         (let ((valvoid (not (with-current-buffer buffer (boundp variable))))
 644               (permanent-local (get variable 'permanent-local))
 645               val val-start-pos locus)
 646           ;; Extract the value before setting up the output buffer,
 647           ;; in case `buffer' *is* the output buffer.
 648           (unless valvoid
 649             (with-selected-frame frame
 650               (with-current-buffer buffer
 651                 (setq val (symbol-value variable)
 652                       locus (variable-binding-locus variable)))))
 653           (help-setup-xref (list #'describe-variable variable buffer)
 654                            (called-interactively-p 'interactive))
 655           (with-help-window (help-buffer)
 656             (with-current-buffer buffer
 657               (prin1 variable)
 658               (setq file-name (find-lisp-object-file-name variable 'defvar))
 659
 660               (if file-name
 661                   (progn
 662                     (princ " is a variable defined in `")
 663                     (princ (if (eq file-name 'C-source)
 664                                "C source code"
 665                              (file-name-nondirectory file-name)))
 666                     (princ "'.\n")
 667                     (with-current-buffer standard-output
 668                       (save-excursion
 669                         (re-search-backward "`\\([^`']+\\)'" nil t)
 670                         (help-xref-button 1 'help-variable-def
 671                                           variable file-name)))
 672                     (if valvoid
 673                         (princ "It is void as a variable.")
 674                       (princ "Its ")))
 675                 (if valvoid
 676                     (princ " is void as a variable.")
 677                   (princ "'s "))))
 678             (unless valvoid
 679               (with-current-buffer standard-output
 680                 (setq val-start-pos (point))
 681                 (princ "value is ")
 682                 (let ((from (point))
 683                       (line-beg (line-beginning-position))
 684                       (print-rep
 685                        (let ((print-quoted t))
 686                          (prin1-to-string val))))
 687                   (if (< (+ (length print-rep) (point) (- line-beg)) 68)
 688                       (insert print-rep)
 689                     (terpri)
 690                     (pp val)
 691                     (if (< (point) (+ 68 (line-beginning-position 0)))
 692                         (delete-region from (1+ from))
 693                       (delete-region (1- from) from)))
 694                   (let* ((sv (get variable 'standard-value))
 695                          (origval (and (consp sv)
 696                                        (condition-case nil
 697                                            (eval (car sv))
 698                                          (error :help-eval-error)))))
 699                     (when (and (consp sv)
 700                                (not (equal origval val))
 701                                (not (equal origval :help-eval-error)))
 702                       (princ "\nOriginal value was \n")
 703                       (setq from (point))
 704                       (pp origval)
 705                       (if (< (point) (+ from 20))
 706                           (delete-region (1- from) from)))))))
 707             (terpri)
 708             (when locus
 709               (cond
 710                ((bufferp locus)
 711                 (princ (format "Local in buffer %s; "
 712                                (buffer-name buffer))))
 713                ((framep locus)
 714                 (princ (format "It is a frame-local variable; ")))
 715                ((terminal-live-p locus)
 716                 (princ (format "It is a terminal-local variable; ")))
 717                (t
 718                 (princ (format "It is local to %S" locus))))
 719               (if (not (default-boundp variable))
 720                   (princ "globally void")
 721                 (let ((global-val (default-value variable)))
 722                   (with-current-buffer standard-output
 723                     (princ "global value is ")
 724                     (if (eq val global-val)
 725                         (princ "the same.")
 726                       (terpri)
 727                       ;; Fixme: pp can take an age if you happen to
 728                       ;; ask for a very large expression.  We should
 729                       ;; probably print it raw once and check it's a
 730                       ;; sensible size before prettyprinting.  -- fx
 731                       (let ((from (point)))
 732                         (pp global-val)
 733                         ;; See previous comment for this function.
 734                         ;; (help-xref-on-pp from (point))
 735                         (if (< (point) (+ from 20))
 736                             (delete-region (1- from) from)))))))
 737               (terpri))
 738
 739             ;; If the value is large, move it to the end.
 740             (with-current-buffer standard-output
 741               (when (> (count-lines (point-min) (point-max)) 10)
 742                 ;; Note that setting the syntax table like below
 743                 ;; makes forward-sexp move over a `'s' at the end
 744                 ;; of a symbol.
 745                 (set-syntax-table emacs-lisp-mode-syntax-table)
 746                 (goto-char val-start-pos)
 747                 ;; The line below previously read as
 748                 ;; (delete-region (point) (progn (end-of-line) (point)))
 749                 ;; which suppressed display of the buffer local value for
 750                 ;; large values.
 751                 (when (looking-at "value is") (replace-match ""))
 752                 (save-excursion
 753                   (insert "\n\nValue:")
 754                   (set (make-local-variable 'help-button-cache)
 755                        (point-marker)))
 756                 (insert "value is shown ")
 757                 (insert-button "below"
 758                                'action help-button-cache
 759                                'follow-link t
 760                                'help-echo "mouse-2, RET: show value")
 761                 (insert ".\n")))
 762             (terpri)
 763
 764             (let* ((alias (condition-case nil
 765                               (indirect-variable variable)
 766                             (error variable)))
 767                    (obsolete (get variable 'byte-obsolete-variable))
 768                    (use (car obsolete))
 769                    (safe-var (get variable 'safe-local-variable))
 770                    (doc (or (documentation-property
 771                              variable 'variable-documentation)
 772                             (documentation-property
 773                              alias 'variable-documentation)))
 774                    (extra-line nil))
 775
 776               ;; Mention if it's a local variable.
 777               (cond
 778                ((and (local-variable-if-set-p variable)
 779                      (or (not (local-variable-p variable))
 780                          (with-temp-buffer
 781                            (local-variable-if-set-p variable))))
 782                 (setq extra-line t)
 783                 (princ "  Automatically becomes ")
 784                 (if permanent-local
 785                     (princ "permanently "))
 786                 (princ "buffer-local when set.\n"))
 787                ((not permanent-local))
 788                ((bufferp locus)
 789                 (setq extra-line t)
 790                 (princ "  This variable's buffer-local value is permanent.\n"))
 791                (t
 792                 (setq extra-line t)
 793                 (princ "  This variable's value is permanent \
 794 if it is given a local binding.\n")))
 795
 796               ;; Mention if it's an alias.
 797               (unless (eq alias variable)
 798                 (setq extra-line t)
 799                 (princ (format "  This variable is an alias for `%s'.\n" alias)))
 800
 801               (when obsolete
 802                 (setq extra-line t)
 803                 (princ "  This variable is obsolete")
 804                 (if (nth 2 obsolete)
 805                     (princ (format " since %s" (nth 2 obsolete))))
 806                 (princ (cond ((stringp use) (concat ";\n  " use))
 807                              (use (format ";\n  use `%s' instead." (car obsolete)))
 808                              (t ".")))
 809                 (terpri))
 810
 811               (when (member (cons variable val)
 812                             (with-current-buffer buffer
 813                               file-local-variables-alist))
 814                 (setq extra-line t)
 815                 (if (member (cons variable val)
 816                              (with-current-buffer buffer
 817                                dir-local-variables-alist))
 818                     (let ((file (and (buffer-file-name buffer)
 819                                       (not (file-remote-p
 820                                             (buffer-file-name buffer)))
 821                                       (dir-locals-find-file
 822                                        (buffer-file-name buffer))))
 823                           (dir-file t))
 824                       (princ "  This variable's value is directory-local")
 825                       (if (null file)
 826                           (princ ".\n")
 827                         (princ ", set ")
 828                         (if (consp file) ; result from cache
 829                             ;; If the cache element has an mtime, we
 830                             ;; assume it came from a file.
 831                             (if (nth 2 file)
 832                                 (setq file (expand-file-name
 833                                             dir-locals-file (car file)))
 834                               ;; Otherwise, assume it was set directly.
 835                               (setq file (car file)
 836                                     dir-file nil)))
 837                         (princ (if dir-file
 838                                    "by the file\n  `"
 839                                  "for the directory\n  `"))
 840                         (with-current-buffer standard-output
 841                           (insert-text-button
 842                            file 'type 'help-dir-local-var-def
 843                            'help-args (list variable file)))
 844                         (princ "'.\n")))
 845                   (princ "  This variable's value is file-local.\n")))
 846
 847               (when (memq variable ignored-local-variables)
 848                 (setq extra-line t)
 849                 (princ "  This variable is ignored as a file-local \
 850 variable.\n"))
 851
 852               ;; Can be both risky and safe, eg auto-fill-function.
 853               (when (risky-local-variable-p variable)
 854                 (setq extra-line t)
 855                 (princ "  This variable may be risky if used as a \
 856 file-local variable.\n")
 857                 (when (assq variable safe-local-variable-values)
 858                   (princ "  However, you have added it to \
 859 `safe-local-variable-values'.\n")))
 860
 861               (when safe-var
 862                 (setq extra-line t)
 863                 (princ "  This variable is safe as a file local variable ")
 864                 (princ "if its value\n  satisfies the predicate ")
 865                 (princ (if (byte-code-function-p safe-var)
 866                            "which is a byte-compiled expression.\n"
 867                          (format "`%s'.\n" safe-var))))
 868
 869               (if extra-line (terpri))
 870               (princ "Documentation:\n")
 871               (with-current-buffer standard-output
 872                 (insert (or doc "Not documented as a variable."))))
 873
 874             ;; Make a link to customize if this variable can be customized.
 875             (when (custom-variable-p variable)
 876               (let ((customize-label "customize"))
 877                 (terpri)
 878                 (terpri)
 879                 (princ (concat "You can " customize-label " this variable."))
 880                 (with-current-buffer standard-output
 881                   (save-excursion
 882                     (re-search-backward
 883                      (concat "\\(" customize-label "\\)") nil t)
 884                     (help-xref-button 1 'help-customize-variable variable))))
 885               ;; Note variable's version or package version
 886               (let ((output (describe-variable-custom-version-info variable)))
 887                 (when output
 888                   (terpri)
 889                   (terpri)
 890                   (princ output))))
 891
 892             (with-current-buffer standard-output
 893               ;; Return the text we displayed.
 894               (buffer-string))))))))
 895
 896
 897 ;;;###autoload
 898 (defun describe-syntax (&optional buffer)
 899   "Describe the syntax specifications in the syntax table of BUFFER.
 900 The descriptions are inserted in a help buffer, which is then displayed.
 901 BUFFER defaults to the current buffer."
 902   (interactive)
 903   (setq buffer (or buffer (current-buffer)))
 904   (help-setup-xref (list #'describe-syntax buffer)
 905                    (called-interactively-p 'interactive))
 906   (with-help-window (help-buffer)
 907     (let ((table (with-current-buffer buffer (syntax-table))))
 908       (with-current-buffer standard-output
 909         (describe-vector table 'internal-describe-syntax-value)
 910         (while (setq table (char-table-parent table))
 911           (insert "\nThe parent syntax table is:")
 912           (describe-vector table 'internal-describe-syntax-value))))))
 913
 914 (defun help-describe-category-set (value)
 915   (insert (cond
 916            ((null value) "default")
 917            ((char-table-p value) "deeper char-table ...")
 918            (t (condition-case nil
 919                   (category-set-mnemonics value)
 920                 (error "invalid"))))))
 921
 922 ;;;###autoload
 923 (defun describe-categories (&optional buffer)
 924   "Describe the category specifications in the current category table.
 925 The descriptions are inserted in a buffer, which is then displayed.
 926 If BUFFER is non-nil, then describe BUFFER's category table instead.
 927 BUFFER should be a buffer or a buffer name."
 928   (interactive)
 929   (setq buffer (or buffer (current-buffer)))
 930   (help-setup-xref (list #'describe-categories buffer)
 931                    (called-interactively-p 'interactive))
 932   (with-help-window (help-buffer)
 933     (let* ((table (with-current-buffer buffer (category-table)))
 934            (docs (char-table-extra-slot table 0)))
 935       (if (or (not (vectorp docs)) (/= (length docs) 95))
 936           (error "Invalid first extra slot in this category table\n"))
 937       (with-current-buffer standard-output
 938         (insert "Legend of category mnemonics (see the tail for the longer description)\n")
 939         (let ((pos (point)) (items 0) lines n)
 940           (dotimes (i 95)
 941             (if (aref docs i) (setq items (1+ items))))
 942           (setq lines (1+ (/ (1- items) 4)))
 943           (setq n 0)
 944           (dotimes (i 95)
 945             (let ((elt (aref docs i)))
 946               (when elt
 947                 (string-match ".*" elt)
 948                 (setq elt (match-string 0 elt))
 949                 (if (>= (length elt) 17)
 950                     (setq elt (concat (substring elt 0 14) "...")))
 951                 (if (< (point) (point-max))
 952                     (move-to-column (* 20 (/ n lines)) t))
 953                 (insert (+ i ?\s) ?: elt)
 954                 (if (< (point) (point-max))
 955                     (forward-line 1)
 956                   (insert "\n"))
 957                 (setq n (1+ n))
 958                 (if (= (% n lines) 0)
 959                     (goto-char pos))))))
 960         (goto-char (point-max))
 961         (insert "\n"
 962                 "character(s)\tcategory mnemonics\n"
 963                 "------------\t------------------")
 964         (describe-vector table 'help-describe-category-set)
 965         (insert "Legend of category mnemonics:\n")
 966         (dotimes (i 95)
 967           (let ((elt (aref docs i)))
 968             (when elt
 969               (if (string-match "\n" elt)
 970                   (setq elt (substring elt (match-end 0))))
 971               (insert (+ i ?\s) ": " elt "\n"))))
 972         (while (setq table (char-table-parent table))
 973           (insert "\nThe parent category table is:")
 974           (describe-vector table 'help-describe-category-set))))))
 975
 976 \f
 977 ;;; Replacements for old lib-src/ programs.  Don't seem especially useful.
 978
 979 ;; Replaces lib-src/digest-doc.c.
 980 ;;;###autoload
 981 (defun doc-file-to-man (file)
 982   "Produce an nroff buffer containing the doc-strings from the DOC file."
 983   (interactive (list (read-file-name "Name of DOC file: " doc-directory
 984                                      internal-doc-file-name t)))
 985   (or (file-readable-p file)
 986       (error "Cannot read file `%s'" file))
 987   (pop-to-buffer (generate-new-buffer "*man-doc*"))
 988   (setq buffer-undo-list t)
 989   (insert ".TH \"Command Summary for GNU Emacs\"\n"
 990           ".AU Richard M. Stallman\n")
 991   (insert-file-contents file)
 992   (let (notfirst)
 993     (while (search-forward "\x1f" nil 'move)
 994       (if (looking-at "S")
 995           (delete-region (1- (point)) (line-end-position))
 996         (delete-char -1)
 997         (if notfirst
 998             (insert "\n.DE\n")
 999           (setq notfirst t))
1000         (insert "\n.SH ")
1001         (insert (if (looking-at "F") "Function " "Variable "))
1002         (delete-char 1)
1003         (forward-line 1)
1004         (insert ".DS L\n"))))
1005   (insert "\n.DE\n")
1006   (setq buffer-undo-list nil)
1007   (nroff-mode))
1008
1009 ;; Replaces lib-src/sorted-doc.c.
1010 ;;;###autoload
1011 (defun doc-file-to-info (file)
1012   "Produce a texinfo buffer with sorted doc-strings from the DOC file."
1013   (interactive (list (read-file-name "Name of DOC file: " doc-directory
1014                                      internal-doc-file-name t)))
1015   (or (file-readable-p file)
1016       (error "Cannot read file `%s'" file))
1017   (let ((i 0) type name doc alist)
1018     (with-temp-buffer
1019       (insert-file-contents file)
1020       ;; The characters "@{}" need special treatment.
1021       (while (re-search-forward "[@{}]" nil t)
1022         (backward-char)
1023         (insert "@")
1024         (forward-char 1))
1025       (goto-char (point-min))
1026       (while (search-forward "\x1f" nil t)
1027         (unless (looking-at "S")
1028           (setq type (char-after)
1029                 name (buffer-substring (1+ (point)) (line-end-position))
1030                 doc (buffer-substring (line-beginning-position 2)
1031                                       (if (search-forward  "\x1f" nil 'move)
1032                                           (1- (point))
1033                                         (point)))
1034                 alist (cons (list name type doc) alist))
1035           (backward-char 1))))
1036     (pop-to-buffer (generate-new-buffer "*info-doc*"))
1037     (setq buffer-undo-list t)
1038     ;; Write the output header.
1039     (insert "\\input texinfo  @c -*-texinfo-*-\n"
1040             "@setfilename emacsdoc.info\n"
1041             "@settitle Command Summary for GNU Emacs\n"
1042             "@finalout\n"
1043             "\n@node Top\n"
1044             "@unnumbered Command Summary for GNU Emacs\n\n"
1045             "@table @asis\n\n"
1046             "@iftex\n"
1047             "@global@let@ITEM@item\n"
1048             "@def@item{@filbreak@vskip5pt@ITEM}\n"
1049             "@font@tensy cmsy10 scaled @magstephalf\n"
1050             "@font@teni cmmi10 scaled @magstephalf\n"
1051             "@def\\{{@tensy@char110}}\n" ; this backslash goes with cmr10
1052             "@def|{{@tensy@char106}}\n"
1053             "@def@{{{@tensy@char102}}\n"
1054             "@def@}{{@tensy@char103}}\n"
1055             "@def<{{@teni@char62}}\n"
1056             "@def>{{@teni@char60}}\n"
1057             "@chardef@@64\n"
1058             "@catcode43=12\n"
1059             "@tableindent-0.2in\n"
1060             "@end iftex\n")
1061     ;; Sort the array by name; within each name, by type (functions first).
1062     (setq alist (sort alist (lambda (e1 e2)
1063                               (if (string-equal (car e1) (car e2))
1064                                   (<= (cadr e1) (cadr e2))
1065                                 (string-lessp (car e1) (car e2))))))
1066     ;; Print each function.
1067     (dolist (e alist)
1068       (insert "\n@item "
1069               (if (char-equal (cadr e) ?\F) "Function" "Variable")
1070               " @code{" (car e) "}\n@display\n"
1071               (nth 2 e)
1072               "\n@end display\n")
1073       ;; Try to avoid a save size overflow in the TeX output routine.
1074       (if (zerop (setq i (% (1+ i) 100)))
1075           (insert "\n@end table\n@table @asis\n")))
1076     (insert "@end table\n"
1077             "@bye\n")
1078     (setq buffer-undo-list nil)
1079     (texinfo-mode)))
1080
1081 (provide 'help-fns)
1082
1083 ;;; help-fns.el ends here