lisp/info.el

   1 ;;; info.el --- info package for Emacs.
   2
   3 ;; Copyright (C) 1985, 1986, 1992 Free Software Foundation, Inc.
   4
   5 ;; Maintainer: FSF
   6 ;; Keywords: help
   7
   8 ;; This file is part of GNU Emacs.
   9
  10 ;; GNU Emacs is free software; you can redistribute it and/or modify
  11 ;; it under the terms of the GNU General Public License as published by
  12 ;; the Free Software Foundation; either version 2, or (at your option)
  13 ;; any later version.
  14
  15 ;; GNU Emacs is distributed in the hope that it will be useful,
  16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ;; GNU General Public License for more details.
  19
  20 ;; You should have received a copy of the GNU General Public License
  21 ;; along with GNU Emacs; see the file COPYING.  If not, write to
  22 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  23
  24 ;;; Commentary:
  25
  26 ;;; Note that nowadays we expect info files to be made using makeinfo.
  27
  28 ;;; Code:
  29
  30 (defvar Info-history nil
  31   "List of info nodes user has visited.
  32 Each element of list is a list (FILENAME NODENAME BUFFERPOS).")
  33
  34 (defvar Info-enable-edit nil
  35   "*Non-nil means the \\<info-mode-map>\\[Info-edit] command in Info can edit the current node.
  36 This is convenient if you want to write info files by hand.
  37 However, we recommend that you not do this.
  38 It is better to write a Texinfo file and generate the Info file from that,
  39 because that gives you a printed manual as well.")
  40
  41 (defvar Info-enable-active-nodes t
  42   "Non-nil allows Info to execute Lisp code associated with nodes.
  43 The Lisp code is executed when the node is selected.")
  44
  45 (defvar Info-default-directory-list nil
  46   "List of default directories to search for Info documentation files.
  47 This value is used as the default for `Info-directory-list'.  It is set
  48 in paths.el.")
  49
  50 (defvar Info-directory-list nil
  51   "List of directories to search for Info documentation files.
  52 nil means not yet initialized.  In this case, Info uses the environment
  53 variable INFOPATH to initialize it, or `Info-default-directory-list'
  54 if there is no INFOPATH variable in the environment.")
  55
  56 (defvar Info-current-file nil
  57   "Info file that Info is now looking at, or nil.")
  58
  59 (defvar Info-current-subfile nil
  60   "Info subfile that is actually in the *info* buffer now,
  61 or nil if current info file is not split into subfiles.")
  62
  63 (defvar Info-current-node nil
  64   "Name of node that Info is now looking at, or nil.")
  65
  66 (defvar Info-tag-table-marker (make-marker)
  67   "Marker pointing at beginning of current Info file's tag table.
  68 Marker points nowhere if file has no tag table.")
  69
  70 (defvar Info-index-alternatives nil
  71   "List of possible matches for last Info-index command.")
  72
  73 (defvar Info-suffix-list '( (""        . nil)
  74                             (".info"   . nil)
  75                             (".Z"      . "uncompress")
  76                             (".Y"      . "unyabba")
  77                             (".z"      . "gunzip")
  78                             (".info.Z" . "uncompress")
  79                             (".info.Y" . "unyabba")
  80                             (".z"      . "gunzip"))
  81   "List of file name suffixes and associated decoding commands.
  82 Each entry should be (SUFFIX . STRING); the file is given to
  83 the command as standard input.  If STRING is nil, no decoding is done.")
  84
  85 (defun info-insert-file-contents (filename &optional visit)
  86   "Insert the contents of an info file in the current buffer.
  87 Do the right thing if the file has been compressed or zipped."
  88   (if (null (catch 'ok
  89               (mapcar
  90                (function
  91                 (lambda (x)
  92                   (let ((compressed (concat filename (car x))))
  93                     (if (file-exists-p compressed)
  94                         (progn
  95                           (insert-file-contents compressed visit)
  96                           (if (cdr x)
  97                               (let ((buffer-read-only nil))
  98                                 (shell-command-on-region
  99                                  (point-min) (point-max) (cdr x) t)))
 100                           (throw 'ok t))))))
 101                Info-suffix-list)
 102               nil))
 103       (error "Can't find %s or any compressed version of it!" filename)))
 104
 105 ;;;###autoload
 106 (defun info (&optional file)
 107   "Enter Info, the documentation browser.
 108 Optional argument FILE specifies the file to examine;
 109 the default is the top-level directory of Info.
 110
 111 In interactive use, a prefix argument directs this command
 112 to read a file name from the minibuffer."
 113   (interactive (if current-prefix-arg
 114                    (list (read-file-name "Info file name: " nil nil t))))
 115   (or Info-directory-list
 116       (setq Info-directory-list
 117             (let ((path (getenv "INFOPATH")))
 118               (if path
 119                   (let ((list nil)
 120                         idx)
 121                     (while (> (length path) 0)
 122                       (setq idx (or (string-match ":" path) (length path))
 123                             list (cons (substring path 0 idx) list)
 124                             path (substring path (min (1+ idx)
 125                                                       (length path)))))
 126                     (nreverse list))
 127                 Info-default-directory-list))))
 128   (if file
 129       (Info-goto-node (concat "(" file ")"))
 130     (if (get-buffer "*info*")
 131         (switch-to-buffer "*info*")
 132       (Info-directory))))
 133
 134 ;; Go to an info node specified as separate filename and nodename.
 135 ;; no-going-back is non-nil if recovering from an error in this function;
 136 ;; it says do not attempt further (recursive) error recovery.
 137 (defun Info-find-node (filename nodename &optional no-going-back)
 138   ;; Convert filename to lower case if not found as specified.
 139   ;; Expand it.
 140   (if filename
 141       (let (temp temp-downcase found)
 142         (setq filename (substitute-in-file-name filename))
 143         (if (string= (downcase (file-name-nondirectory filename)) "dir")
 144             (setq found t)
 145           (let ((dirs (if (string-match "^\\./" filename)
 146                           ;; If specified name starts with `./'
 147                           ;; then just try current directory.
 148                           '("./")
 149                         Info-directory-list)))
 150             ;; Search the directory list for file FILENAME.
 151             (while (and dirs (not found))
 152               (setq temp (expand-file-name filename (car dirs)))
 153               (setq temp-downcase
 154                     (expand-file-name (downcase filename) (car dirs)))
 155               ;; Try several variants of specified name.
 156               (catch 'foundit
 157                 (mapcar
 158                  (function
 159                   (lambda (x)
 160                     (if (file-exists-p (concat temp (car x)))
 161                         (progn
 162                           (setq found temp)
 163                           (throw 'foundit nil)))
 164                     (if (file-exists-p (concat temp-downcase (car x)))
 165                         (progn
 166                           (setq found temp-downcase)
 167                           (throw 'foundit nil)))))
 168                  Info-suffix-list))
 169               (setq dirs (cdr dirs)))))
 170         (if found
 171             (setq filename found)
 172           (error "Info file %s does not exist" filename))))
 173   ;; Record the node we are leaving.
 174   (if (and Info-current-file (not no-going-back))
 175       (setq Info-history
 176             (cons (list Info-current-file Info-current-node (point))
 177                   Info-history)))
 178   ;; Go into info buffer.
 179   (switch-to-buffer "*info*")
 180   (buffer-disable-undo (current-buffer))
 181   (or (eq major-mode 'Info-mode)
 182       (Info-mode))
 183   (widen)
 184   (setq Info-current-node nil)
 185   (unwind-protect
 186       (progn
 187         ;; Switch files if necessary
 188         (or (null filename)
 189             (equal Info-current-file filename)
 190             (let ((buffer-read-only nil))
 191               (setq Info-current-file nil
 192                     Info-current-subfile nil
 193                     Info-index-alternatives nil
 194                     buffer-file-name nil)
 195               (erase-buffer)
 196               (if (eq filename t)
 197                   (Info-insert-dir)
 198                 (info-insert-file-contents filename t)
 199                 (setq default-directory (file-name-directory filename)))
 200               (set-buffer-modified-p nil)
 201               ;; See whether file has a tag table.  Record the location if yes.
 202               (set-marker Info-tag-table-marker nil)
 203               (goto-char (point-max))
 204               (forward-line -8)
 205               (or (equal nodename "*")
 206                   (not (search-forward "\^_\nEnd tag table\n" nil t))
 207                   (let (pos)
 208                     ;; We have a tag table.  Find its beginning.
 209                     ;; Is this an indirect file?
 210                     (search-backward "\nTag table:\n")
 211                     (setq pos (point))
 212                     (if (save-excursion
 213                           (forward-line 2)
 214                           (looking-at "(Indirect)\n"))
 215                         ;; It is indirect.  Copy it to another buffer
 216                         ;; and record that the tag table is in that buffer.
 217                         (save-excursion
 218                           (let ((buf (current-buffer)))
 219                             (set-buffer (get-buffer-create " *info tag table*"))
 220                             (buffer-disable-undo (current-buffer))
 221                             (setq case-fold-search t)
 222                             (erase-buffer)
 223                             (insert-buffer-substring buf)
 224                             (set-marker Info-tag-table-marker
 225                                         (match-end 0))))
 226                       (set-marker Info-tag-table-marker pos))))
 227               (setq Info-current-file
 228                     (if (eq filename t) "dir"
 229                       (file-name-sans-versions buffer-file-name)))))
 230         (if (equal nodename "*")
 231             (progn (setq Info-current-node nodename)
 232                    (Info-set-mode-line))
 233           ;; Search file for a suitable node.
 234           (let ((guesspos (point-min))
 235                 (regexp (concat "Node: *" (regexp-quote nodename) " *[,\t\n\177]")))
 236             ;; First get advice from tag table if file has one.
 237             ;; Also, if this is an indirect info file,
 238             ;; read the proper subfile into this buffer.
 239             (if (marker-position Info-tag-table-marker)
 240                 (save-excursion
 241                   (set-buffer (marker-buffer Info-tag-table-marker))
 242                   (goto-char Info-tag-table-marker)
 243                   (if (re-search-forward regexp nil t)
 244                       (progn
 245                         (setq guesspos (read (current-buffer)))
 246                         ;; If this is an indirect file,
 247                         ;; determine which file really holds this node
 248                         ;; and read it in.
 249                         (if (not (eq (current-buffer) (get-buffer "*info*")))
 250                             (setq guesspos
 251                                   (Info-read-subfile guesspos))))
 252                     (error "No such node: \"%s\"" nodename))))
 253             (goto-char (max (point-min) (- guesspos 1000)))
 254             ;; Now search from our advised position (or from beg of buffer)
 255             ;; to find the actual node.
 256             (catch 'foo
 257               (while (search-forward "\n\^_" nil t)
 258                 (forward-line 1)
 259                 (let ((beg (point)))
 260                   (forward-line 1)
 261                   (if (re-search-backward regexp beg t)
 262                       (throw 'foo t))))
 263               (error "No such node: %s" nodename)))
 264           (Info-select-node)))
 265     ;; If we did not finish finding the specified node,
 266     ;; go back to the previous one.
 267     (or Info-current-node no-going-back
 268         (let ((hist (car Info-history)))
 269           (setq Info-history (cdr Info-history))
 270           (Info-find-node (nth 0 hist) (nth 1 hist) t)
 271           (goto-char (nth 2 hist)))))
 272   (goto-char (point-min)))
 273
 274 ;; Cache the contents of the (virtual) dir file, once we have merged
 275 ;; it for the first time, so we can save time subsequently.
 276 (defvar Info-dir-contents nil)
 277
 278 ;; Cache for the directory we decided to use for the default-directory
 279 ;; of the merged dir text.
 280 (defvar Info-dir-contents-directory nil)
 281
 282 ;; Construct the Info directory node by merging the files named `dir'
 283 ;; from various directories.  Set the *info* buffer's
 284 ;; default-directory to the first directory we actually get any text
 285 ;; from.
 286 (defun Info-insert-dir ()
 287   (if Info-dir-contents
 288       (insert Info-dir-contents)
 289     (let ((dirs Info-directory-list)
 290           buffers buffer others nodes)
 291
 292       ;; Search the directory list for the directory file.
 293       (while dirs
 294         ;; Try several variants of specified name.
 295         ;; Try upcasing, appending `.info', or both.
 296         (let* (temp
 297                (buffer
 298                 (cond
 299                  ((progn (setq temp (expand-file-name "DIR" (car dirs)))
 300                          (file-exists-p temp))
 301                   (find-file-noselect temp))
 302                  ((progn (setq temp (expand-file-name "dir" (car dirs)))
 303                          (file-exists-p temp))
 304                   (find-file-noselect temp))
 305                  ((progn (setq temp (expand-file-name "DIR.INFO" (car dirs)))
 306                          (file-exists-p temp))
 307                   (find-file-noselect temp))
 308                  ((progn (setq temp (expand-file-name "dir.info" (car dirs)))
 309                          (file-exists-p temp))
 310                   (find-file-noselect temp)))))
 311           (if buffer (setq buffers (cons buffer buffers)))
 312           (setq dirs (cdr dirs))))
 313
 314       ;; Distinguish the dir file that comes with Emacs from all the
 315       ;; others.  [This sounds like baloney - who knows what order
 316       ;; Info-directory-list is in, especially after checking the
 317       ;; INFOPATH variable, and why should Emacs's dir be special?  If
 318       ;; you understand what this comment should have said, please
 319       ;; change it.]
 320       (setq buffer (car buffers)
 321             others (cdr buffers))
 322
 323       ;; Insert the entire original dir file as a start; use its
 324       ;; default directory as the default directory for the whole
 325       ;; concatenation.
 326       (insert-buffer buffer)
 327       (setq Info-dir-contents-directory (save-excursion
 328                                           (set-buffer buffer)
 329                                           default-directory))
 330
 331       ;; Look at each of the other buffers one by one.
 332       (while others
 333         (let ((other (car others)))
 334           ;; In each, find all the menus.
 335           (save-excursion
 336             (set-buffer other)
 337             (goto-char (point-min))
 338             ;; Find each menu, and add an elt to NODES for it.
 339             (while (re-search-forward "^\\* Menu:" nil t)
 340               (let (beg nodename end)
 341                 (forward-line 1)
 342                 (setq beg (point))
 343                 (search-backward "\n\1f")
 344                 (search-forward "Node: ")
 345                 (setq nodename (Info-following-node-name))
 346                 (search-forward "\n\1f" nil 'move)
 347                 (beginning-of-line)
 348                 (setq end (point))
 349                 (setq nodes (cons (list nodename other beg end) nodes))))))
 350         (setq others (cdr others)))
 351       ;; Add to the main menu a menu item for each other node.
 352       (re-search-forward "^\\* Menu:")
 353       (forward-line 1)
 354       (let ((menu-items '("top"))
 355             (nodes nodes)
 356             (case-fold-search t)
 357             (end (save-excursion (search-forward "\1f" nil t) (point))))
 358         (while nodes
 359           (let ((nodename (car (car nodes))))
 360             (or (member (downcase nodename) menu-items)
 361                 (re-search-forward (concat "^\\* " (regexp-quote nodename) ":")
 362                                    end t)
 363                 (progn
 364                   (insert "* " nodename "\n")
 365                   (setq menu-items (cons nodename menu-items)))))
 366           (setq nodes (cdr nodes))))
 367       ;; Now take each node of each of the other buffers
 368       ;; and merge it into the main buffer.
 369       (while nodes
 370         (let ((nodename (car (car nodes))))
 371           (goto-char (point-min))
 372           ;; Find the like-named node in the main buffer.
 373           (if (re-search-forward (concat "\n\1f.*\n.*Node: "
 374                                          (regexp-quote nodename)
 375                                          "[,\n\t]")
 376                                  nil t)
 377               (progn
 378                 (search-forward "\n\1f" nil 'move)
 379                 (beginning-of-line))
 380             ;; If none exists, add one.
 381             (goto-char (point-max))
 382             (insert "\1f\nFile: dir\tnode: " nodename "\n\n* Menu:\n\n"))
 383           ;; Merge the text from the other buffer's menu
 384           ;; into the menu in the like-named node in the main buffer.
 385           (apply 'insert-buffer-substring (cdr (car nodes)))
 386           (insert "\n"))
 387         (setq nodes (cdr nodes)))
 388       ;; Kill all the buffers we just made.
 389       (while buffers
 390         (kill-buffer (car buffers))
 391         (setq buffers (cdr buffers))))
 392     (setq Info-dir-contents (buffer-string)))
 393   (setq default-directory Info-dir-contents-directory))
 394
 395 (defun Info-read-subfile (nodepos)
 396   (set-buffer (marker-buffer Info-tag-table-marker))
 397   (goto-char (point-min))
 398   (search-forward "\n\^_")
 399   (let (lastfilepos
 400         lastfilename)
 401     (forward-line 2)
 402     (catch 'foo
 403       (while (not (looking-at "\^_"))
 404         (if (not (eolp))
 405             (let ((beg (point))
 406                   thisfilepos thisfilename)
 407               (search-forward ": ")
 408               (setq thisfilename  (buffer-substring beg (- (point) 2)))
 409               (setq thisfilepos (read (current-buffer)))
 410               ;; read in version 19 stops at the end of number.
 411               ;; Advance to the next line.
 412               (forward-line 1)
 413               (if (> thisfilepos nodepos)
 414                   (throw 'foo t))
 415               (setq lastfilename thisfilename)
 416               (setq lastfilepos thisfilepos))
 417           (forward-line 1))))
 418     (set-buffer (get-buffer "*info*"))
 419     (or (equal Info-current-subfile lastfilename)
 420         (let ((buffer-read-only nil))
 421           (setq buffer-file-name nil)
 422           (widen)
 423           (erase-buffer)
 424           (info-insert-file-contents lastfilename)
 425           (set-buffer-modified-p nil)
 426           (setq Info-current-subfile lastfilename)))
 427     (goto-char (point-min))
 428     (search-forward "\n\^_")
 429     (+ (- nodepos lastfilepos) (point))))
 430
 431 ;; Select the info node that point is in.
 432 (defun Info-select-node ()
 433   (save-excursion
 434    ;; Find beginning of node.
 435    (search-backward "\n\^_")
 436    (forward-line 2)
 437    ;; Get nodename spelled as it is in the node.
 438    (re-search-forward "Node:[ \t]*")
 439    (setq Info-current-node
 440          (buffer-substring (point)
 441                            (progn
 442                             (skip-chars-forward "^,\t\n")
 443                             (point))))
 444    (Info-set-mode-line)
 445    ;; Find the end of it, and narrow.
 446    (beginning-of-line)
 447    (let (active-expression)
 448      (narrow-to-region (point)
 449                        (if (re-search-forward "\n[\^_\f]" nil t)
 450                            (prog1
 451                             (1- (point))
 452                             (if (looking-at "[\n\^_\f]*execute: ")
 453                                 (progn
 454                                   (goto-char (match-end 0))
 455                                   (setq active-expression
 456                                         (read (current-buffer))))))
 457                          (point-max)))
 458      (if Info-enable-active-nodes (eval active-expression)))))
 459
 460 (defun Info-set-mode-line ()
 461   (setq mode-line-buffer-identification
 462         (concat
 463          "Info:  ("
 464          (if Info-current-file
 465              (file-name-nondirectory Info-current-file)
 466            "")
 467          ")"
 468          (or Info-current-node ""))))
 469 \f
 470 ;; Go to an info node specified with a filename-and-nodename string
 471 ;; of the sort that is found in pointers in nodes.
 472
 473 (defun Info-goto-node (nodename)
 474   "Go to info node named NAME.  Give just NODENAME or (FILENAME)NODENAME."
 475   (interactive "sGoto node: ")
 476   (let (filename)
 477     (string-match "\\s *\\((\\s *\\([^\t)]*\\)\\s *)\\s *\\|\\)\\(.*\\)"
 478                   nodename)
 479     (setq filename (if (= (match-beginning 1) (match-end 1))
 480                        ""
 481                      (substring nodename (match-beginning 2) (match-end 2)))
 482           nodename (substring nodename (match-beginning 3) (match-end 3)))
 483     (let ((trim (string-match "\\s *\\'" filename)))
 484       (if trim (setq filename (substring filename 0 trim))))
 485     (let ((trim (string-match "\\s *\\'" nodename)))
 486       (if trim (setq nodename (substring nodename 0 trim))))
 487     (Info-find-node (if (equal filename "") nil filename)
 488                     (if (equal nodename "") "Top" nodename))))
 489 \f
 490 (defun Info-restore-point (hl)
 491   "If this node has been visited, restore the point value when we left."
 492   (if hl
 493       (if (and (equal (nth 0 (car hl)) Info-current-file)
 494                (equal (nth 1 (car hl)) Info-current-node))
 495           (goto-char (nth 2 (car hl)))
 496         (Info-restore-point (cdr hl)))))
 497 \f
 498 (defvar Info-last-search nil
 499   "Default regexp for \\<info-mode-map>\\[Info-search] command to search for.")
 500
 501 (defun Info-search (regexp)
 502   "Search for REGEXP, starting from point, and select node it's found in."
 503   (interactive "sSearch (regexp): ")
 504   (if (equal regexp "")
 505       (setq regexp Info-last-search)
 506     (setq Info-last-search regexp))
 507   (let ((found ()) current
 508         (onode Info-current-node)
 509         (ofile Info-current-file)
 510         (opoint (point))
 511         (osubfile Info-current-subfile))
 512     (save-excursion
 513       (save-restriction
 514         (widen)
 515         (if (null Info-current-subfile)
 516             (progn (re-search-forward regexp) (setq found (point)))
 517           (condition-case err
 518               (progn (re-search-forward regexp) (setq found (point)))
 519             (search-failed nil)))))
 520     (if (not found) ;can only happen in subfile case -- else would have erred
 521         (unwind-protect
 522             (let ((list ()))
 523               (set-buffer (marker-buffer Info-tag-table-marker))
 524               (goto-char (point-min))
 525               (search-forward "\n\^_\nIndirect:")
 526               (save-restriction
 527                 (narrow-to-region (point)
 528                                   (progn (search-forward "\n\^_")
 529                                          (1- (point))))
 530                 (goto-char (point-min))
 531                 (search-forward (concat "\n" osubfile ": "))
 532                 (beginning-of-line)
 533                 (while (not (eobp))
 534                   (re-search-forward "\\(^.*\\): [0-9]+$")
 535                   (goto-char (+ (match-end 1) 2))
 536                   (setq list (cons (cons (read (current-buffer))
 537                                          (buffer-substring (match-beginning 1)
 538                                                            (match-end 1)))
 539                                    list))
 540                   (goto-char (1+ (match-end 0))))
 541                 (setq list (nreverse list)
 542                       current (car (car list))
 543                       list (cdr list)))
 544               (while list
 545                 (message "Searching subfile %s..." (cdr (car list)))
 546                 (Info-read-subfile (car (car list)))
 547                 (setq list (cdr list))
 548                 (goto-char (point-min))
 549                 (if (re-search-forward regexp nil t)
 550                     (setq found (point) list ())))
 551               (if found
 552                   (message "")
 553                 (signal 'search-failed (list regexp))))
 554           (if (not found)
 555               (progn (Info-read-subfile opoint)
 556                      (goto-char opoint)
 557                      (Info-select-node)))))
 558     (widen)
 559     (goto-char found)
 560     (Info-select-node)
 561     (or (and (equal onode Info-current-node)
 562              (equal ofile Info-current-file))
 563         (setq Info-history (cons (list ofile onode opoint)
 564                                  Info-history)))))
 565 \f
 566 ;; Extract the value of the node-pointer named NAME.
 567 ;; If there is none, use ERRORNAME in the error message;
 568 ;; if ERRORNAME is nil, just return nil.
 569 (defun Info-extract-pointer (name &optional errorname)
 570   (save-excursion
 571    (goto-char (point-min))
 572    (forward-line 1)
 573    (if (re-search-backward (concat name ":") nil t)
 574        (progn
 575          (goto-char (match-end 0))
 576          (Info-following-node-name))
 577      (if (eq errorname t)
 578          nil
 579        (error (concat "Node has no " (capitalize (or errorname name))))))))
 580
 581 ;; Return the node name in the buffer following point.
 582 ;; ALLOWEDCHARS, if non-nil, goes within [...] to make a regexp
 583 ;; saying which chas may appear in the node name.
 584 (defun Info-following-node-name (&optional allowedchars)
 585   (skip-chars-forward " \t")
 586   (buffer-substring
 587    (point)
 588    (progn
 589      (while (looking-at (concat "[" (or allowedchars "^,\t\n") "]"))
 590        (skip-chars-forward (concat (or allowedchars "^,\t\n") "("))
 591        (if (looking-at "(")
 592            (skip-chars-forward "^)")))
 593      (skip-chars-backward " ")
 594      (point))))
 595
 596 (defun Info-next ()
 597   "Go to the next node of this node."
 598   (interactive)
 599   (Info-goto-node (Info-extract-pointer "next")))
 600
 601 (defun Info-prev ()
 602   "Go to the previous node of this node."
 603   (interactive)
 604   (Info-goto-node (Info-extract-pointer "prev[ious]*" "previous")))
 605
 606 (defun Info-up ()
 607   "Go to the superior node of this node."
 608   (interactive)
 609   (Info-goto-node (Info-extract-pointer "up"))
 610   (Info-restore-point Info-history))
 611
 612 (defun Info-last ()
 613   "Go back to the last node visited."
 614   (interactive)
 615   (or Info-history
 616       (error "This is the first Info node you looked at"))
 617   (let (filename nodename opoint)
 618     (setq filename (car (car Info-history)))
 619     (setq nodename (car (cdr (car Info-history))))
 620     (setq opoint (car (cdr (cdr (car Info-history)))))
 621     (setq Info-history (cdr Info-history))
 622     (Info-find-node filename nodename)
 623     (setq Info-history (cdr Info-history))
 624     (goto-char opoint)))
 625
 626 (defun Info-directory ()
 627   "Go to the Info directory node."
 628   (interactive)
 629   (Info-find-node "dir" "top"))
 630 \f
 631 (defun Info-follow-reference (footnotename)
 632   "Follow cross reference named NAME to the node it refers to.
 633 NAME may be an abbreviation of the reference name."
 634   (interactive
 635    (let ((completion-ignore-case t)
 636          completions default (start-point (point)) str i)
 637      (save-excursion
 638        (goto-char (point-min))
 639        (while (re-search-forward "\\*note[ \n\t]*\\([^:]*\\):" nil t)
 640          (setq str (buffer-substring
 641                     (match-beginning 1)
 642                     (1- (point))))
 643          ;; See if this one should be the default.
 644          (and (null default)
 645               (< (match-beginning 0) start-point)
 646               (<= start-point (point))
 647               (setq default t))
 648          (setq i 0)
 649          (while (setq i (string-match "[ \n\t]+" str i))
 650            (setq str (concat (substring str 0 i) " "
 651                              (substring str (match-end 0))))
 652            (setq i (1+ i)))
 653          ;; Record as a completion and perhaps as default.
 654          (if (eq default t) (setq default str))
 655          (setq completions
 656                (cons (cons str nil)
 657                      completions))))
 658      (if completions
 659          (list (completing-read (if default
 660                                     (concat "Follow reference named: ("
 661                                             default ") ")
 662                                   "Follow reference named: ")
 663                                 completions default t))
 664        (error "No cross-references in this node"))))
 665   (let (target beg i (str (concat "\\*note " footnotename)))
 666     (while (setq i (string-match " " str i))
 667       (setq str (concat (substring str 0 i) "[ \t\n]+" (substring str (1+ i))))
 668       (setq i (+ i 6)))
 669     (save-excursion
 670       (goto-char (point-min))
 671       (or (re-search-forward str nil t)
 672           (error "No cross-reference named %s" footnotename))
 673       (goto-char (+ (match-beginning 0) 5))
 674       (setq target
 675             (Info-extract-menu-node-name "Bad format cross reference" t)))
 676     (while (setq i (string-match "[ \t\n]+" target i))
 677       (setq target (concat (substring target 0 i) " "
 678                            (substring target (match-end 0))))
 679       (setq i (+ i 1)))
 680     (Info-goto-node target)))
 681
 682 (defun Info-extract-menu-node-name (&optional errmessage multi-line)
 683   (skip-chars-forward " \t\n")
 684   (let ((beg (point))
 685         str i)
 686     (skip-chars-forward "^:")
 687     (forward-char 1)
 688     (setq str
 689           (if (looking-at ":")
 690               (buffer-substring beg (1- (point)))
 691             (skip-chars-forward " \t\n")
 692             (Info-following-node-name (if multi-line "^.,\t" "^.,\t\n"))))
 693     (while (setq i (string-match "\n" str i))
 694       (aset str i ?\ ))
 695     str))
 696
 697 ;; No one calls this and Info-menu-item doesn't exist.
 698 ;;(defun Info-menu-item-sequence (list)
 699 ;;  (while list
 700 ;;    (Info-menu-item (car list))
 701 ;;    (setq list (cdr list))))
 702
 703 (defun Info-menu (menu-item)
 704   "Go to node for menu item named (or abbreviated) NAME.
 705 Completion is allowed, and the menu item point is on is the default."
 706   (interactive
 707    (let ((completions '())
 708          ;; If point is within a menu item, use that item as the default
 709          (default nil)
 710          (p (point))
 711          (last nil))
 712      (save-excursion
 713        (goto-char (point-min))
 714        (if (not (search-forward "\n* menu:" nil t))
 715            (error "No menu in this node"))
 716        (while (re-search-forward
 717                 "\n\\* \\([^:\t\n]*\\):" nil t)
 718          (if (and (null default)
 719                   (prog1 (if last (< last p) nil)
 720                     (setq last (match-beginning 0)))
 721                   (<= p last))
 722              (setq default (car (car completions))))
 723          (setq completions (cons (cons (buffer-substring
 724                                          (match-beginning 1)
 725                                          (match-end 1))
 726                                        (match-beginning 1))
 727                                  completions)))
 728        (if (and (null default) last
 729                 (< last p)
 730                 (<= p (progn (end-of-line) (point))))
 731            (setq default (car (car completions)))))
 732      (let ((item nil))
 733        (while (null item)
 734          (setq item (let ((completion-ignore-case t))
 735                       (completing-read (if default
 736                                            (format "Menu item (default %s): "
 737                                                    default)
 738                                            "Menu item: ")
 739                                        completions nil t)))
 740          ;; we rely on the fact that completing-read accepts an input
 741          ;; of "" even when the require-match argument is true and ""
 742          ;; is not a valid possibility
 743          (if (string= item "")
 744              (if default
 745                  (setq item default)
 746                  ;; ask again
 747                  (setq item nil))))
 748        (list item))))
 749   ;; there is a problem here in that if several menu items have the same
 750   ;; name you can only go to the node of the first with this command.
 751   (Info-goto-node (Info-extract-menu-item menu-item)))
 752
 753 (defun Info-extract-menu-item (menu-item)
 754   (setq menu-item (regexp-quote menu-item))
 755   (save-excursion
 756     (goto-char (point-min))
 757     (or (search-forward "\n* menu:" nil t)
 758         (error "No menu in this node"))
 759     (or (re-search-forward (concat "\n* " menu-item ":") nil t)
 760         (re-search-forward (concat "\n* " menu-item) nil t)
 761         (error "No such item in menu"))
 762     (beginning-of-line)
 763     (forward-char 2)
 764     (Info-extract-menu-node-name)))
 765
 766 ;; If COUNT is nil, use the last item in the menu.
 767 (defun Info-extract-menu-counting (count)
 768   (save-excursion
 769     (goto-char (point-min))
 770     (or (search-forward "\n* menu:" nil t)
 771         (error "No menu in this node"))
 772     (if count
 773         (or (search-forward "\n* " nil t count)
 774             (error "Too few items in menu"))
 775       (while (search-forward "\n* " nil t)
 776         nil))
 777     (Info-extract-menu-node-name)))
 778
 779 (defun Info-nth-menu-item ()
 780   "Go to the node of the Nth menu item.
 781 N is the digit argument used to invoke this command."
 782   (interactive)
 783   (Info-goto-node
 784    (Info-extract-menu-counting
 785     (- (aref (this-command-keys) (1- (length (this-command-keys)))) ?0))))
 786
 787 (defun Info-top-node ()
 788   "Go to the Top node of this file."
 789   (interactive)
 790   (Info-goto-node "Top"))
 791
 792 (defun Info-final-node ()
 793   "Go to the final node in this file."
 794   (interactive)
 795   (Info-goto-node "Top")
 796   (let (Info-history)
 797     ;; Go to the last node in the menu of Top.
 798     (Info-goto-node (Info-extract-menu-counting nil))
 799     ;; If the last node in the menu is not last in pointer structure,
 800     ;; move forward until we can't go any farther.
 801     (while (Info-forward-node t t) nil)
 802     ;; Then keep moving down to last subnode, unless we reach an index.
 803     (while (and (not (string-match "\\<index\\>" Info-current-node))
 804                 (save-excursion (search-forward "\n* Menu:" nil t)))
 805       (Info-goto-node (Info-extract-menu-counting nil)))))
 806
 807 (defun Info-forward-node (&optional not-down no-error)
 808   "Go forward one node, considering all nodes as forming one sequence."
 809   (interactive)
 810   (goto-char (point-min))
 811   (forward-line 1)
 812   ;; three possibilities, in order of priority:
 813   ;;     1. next node is in a menu in this node (but not in an index)
 814   ;;     2. next node is next at same level
 815   ;;     3. next node is up and next
 816   (cond ((and (not not-down)
 817               (save-excursion (search-forward "\n* menu:" nil t))
 818               (not (string-match "\\<index\\>" Info-current-node)))
 819          (Info-goto-node (Info-extract-menu-counting 1))
 820          t)
 821         ((save-excursion (search-backward "next:" nil t))
 822          (Info-next)
 823          t)
 824         ((and (save-excursion (search-backward "up:" nil t))
 825               (not (equal (downcase (Info-extract-pointer "up")) "top")))
 826          (let ((old-node Info-current-node))
 827            (Info-up)
 828            (let (Info-history success)
 829              (unwind-protect
 830                  (setq success (Info-forward-node t no-error))
 831                (or success (Info-goto-node old-node))))))
 832         (no-error nil)
 833         (t (error "No pointer forward from this node"))))
 834
 835 (defun Info-backward-node ()
 836   "Go backward one node, considering all nodes as forming one sequence."
 837   (interactive)
 838   (let ((prevnode (Info-extract-pointer "prev[ious]*" t))
 839         (upnode (Info-extract-pointer "up" t)))
 840     (cond ((and upnode (string-match "(" upnode))
 841            (error "First node in file"))
 842           ((and upnode (or (null prevnode)
 843                            (equal (downcase prevnode) (downcase upnode))))
 844            (Info-up))
 845           (prevnode
 846            ;; If we move back at the same level,
 847            ;; go down to find the last subnode*.
 848            (Info-prev)
 849            (let (Info-history)
 850              (while (and (not (string-match "\\<index\\>" Info-current-node))
 851                          (save-excursion (search-forward "\n* Menu:" nil t)))
 852                (Info-goto-node (Info-extract-menu-counting nil)))))
 853           (t
 854            (error "No pointer backward from this node")))))
 855
 856 (defun Info-exit ()
 857   "Exit Info by selecting some other buffer."
 858   (interactive)
 859   (switch-to-buffer (prog1 (other-buffer (current-buffer))
 860                            (bury-buffer (current-buffer)))))
 861
 862 (defun Info-next-menu-item ()
 863   (interactive)
 864   (save-excursion
 865     (forward-line -1)
 866     (search-forward "\n* menu:" nil t)
 867     (or (search-forward "\n* " nil t)
 868         (error "No more items in menu"))
 869     (Info-goto-node (Info-extract-menu-node-name))))
 870
 871 (defun Info-last-menu-item ()
 872   (interactive)
 873   (save-excursion
 874     (forward-line 1)
 875     (search-backward "\n* menu:" nil t)
 876     (or (search-backward "\n* " nil t)
 877         (error "No previous items in menu"))
 878     (Info-goto-node (Info-extract-menu-node-name))))
 879
 880 (defmacro no-error (&rest body)
 881   (list 'condition-case nil (cons 'progn (append body '(t))) '(error nil)))
 882
 883 (defun Info-next-preorder ()
 884   "Go to the next node, popping up a level if there is none."
 885   (interactive)
 886   (cond ((no-error (Info-next-menu-item))       )
 887         ((no-error (Info-up))                   (forward-line 1))
 888         (t                                      (error "No more nodes"))))
 889
 890 (defun Info-last-preorder ()
 891   "Go to the last node, popping up a level if there is none."
 892   (interactive)
 893   (cond ((no-error (Info-last-menu-item))       )
 894         ((no-error (Info-up))                   (forward-line -1))
 895         (t                                      (error "No previous nodes"))))
 896
 897 (defun Info-scroll-up ()
 898   "Read the next screen.  If end of buffer is visible, go to next entry."
 899   (interactive)
 900   (if (pos-visible-in-window-p (point-max))
 901       (Info-next-preorder)
 902       (scroll-up))
 903   )
 904
 905 (defun Info-scroll-down ()
 906   "Read the previous screen.  If start of buffer is visible, go to last entry."
 907   (interactive)
 908   (if (pos-visible-in-window-p (point-min))
 909       (Info-last-preorder)
 910       (scroll-down))
 911   )
 912
 913 (defun Info-index (topic)
 914   "Look up a string in the index for this file.
 915 The index is defined as the first node in the top-level menu whose
 916 name contains the word \"Index\", plus any immediately following
 917 nodes whose names also contain the word \"Index\".
 918 If there are no exact matches to the specified topic, this chooses
 919 the first match which is a case-insensitive substring of a topic.
 920 Use the `,' command to see the other matches.
 921 Give a blank topic name to go to the Index node itself."
 922   (interactive "sIndex topic: ")
 923   (let ((orignode Info-current-node)
 924         (rnode nil)
 925         (pattern (format "\n\\* \\([^\n:]*%s[^\n:]*\\):[ \t]*\\([^.\n]*\\)\\.[ t]*\\([0-9]*\\)"
 926                          (regexp-quote topic)))
 927         node)
 928     (Info-goto-node "Top")
 929     (or (search-forward "\n* menu:" nil t)
 930         (error "No index"))
 931     (or (re-search-forward "\n\\* \\(.*\\<Index\\>\\)" nil t)
 932         (error "No index"))
 933     (goto-char (match-beginning 1))
 934     (let ((Info-keeping-history nil))
 935       (Info-goto-node (Info-extract-menu-node-name)))
 936     (or (equal topic "")
 937         (let ((matches nil)
 938               (exact nil)
 939               (Info-keeping-history nil)
 940               found)
 941           (while
 942               (progn
 943                 (goto-char (point-min))
 944                 (while (re-search-forward pattern nil t)
 945                   (setq matches
 946                         (cons (list (buffer-substring (match-beginning 1)
 947                                                       (match-end 1))
 948                                     (buffer-substring (match-beginning 2)
 949                                                       (match-end 2))
 950                                     Info-current-node
 951                                     (string-to-int (concat "0"
 952                                                            (buffer-substring
 953                                                             (match-beginning 3)
 954                                                             (match-end 3)))))
 955                               matches)))
 956                 (and (setq node (Info-extract-pointer "next" t))
 957                      (string-match "\\<Index\\>" node)))
 958             (Info-goto-node node))
 959           (or matches
 960               (progn
 961                 (Info-last)
 962                 (error "No \"%s\" in index" topic)))
 963           ;; Here it is a feature that assoc is case-sensitive.
 964           (while (setq found (assoc topic matches))
 965             (setq exact (cons found exact)
 966                   matches (delq found matches)))
 967           (setq Info-index-alternatives (nconc exact (nreverse matches)))
 968           (Info-index-next 0)))))
 969
 970 (defun Info-index-next (num)
 971   "Go to the next matching index item from the last `i' command."
 972   (interactive "p")
 973   (or Info-index-alternatives
 974       (error "No previous `i' command in this file"))
 975   (while (< num 0)
 976     (setq num (+ num (length Info-index-alternatives))))
 977   (while (> num 0)
 978     (setq Info-index-alternatives
 979           (nconc (cdr Info-index-alternatives)
 980                  (list (car Info-index-alternatives)))
 981           num (1- num)))
 982   (Info-goto-node (nth 1 (car Info-index-alternatives)))
 983   (if (> (nth 3 (car Info-index-alternatives)) 0)
 984       (forward-line (nth 3 (car Info-index-alternatives)))
 985     (forward-line 3)  ; don't search in headers
 986     (let ((name (car (car Info-index-alternatives))))
 987       (if (or (re-search-forward (format
 988                                   "\\(Function\\|Command\\): %s\\( \\|$\\)"
 989                                   (regexp-quote name)) nil t)
 990               (search-forward (format "`%s'" name) nil t)
 991               (and (string-match "\\`.*\\( (.*)\\)\\'" name)
 992                    (search-forward
 993                     (format "`%s'" (substring name 0 (match-beginning 1)))
 994                     nil t))
 995               (search-forward name nil t))
 996           (beginning-of-line)
 997         (goto-char (point-min)))))
 998   (message "Found \"%s\" in %s.  %s"
 999            (car (car Info-index-alternatives))
1000            (nth 2 (car Info-index-alternatives))
1001            (if (cdr Info-index-alternatives)
1002                "(Press `,' for more)"
1003              "(Only match)")))
1004
1005 (defun Info-undefined ()
1006   "Make command be undefined in Info."
1007   (interactive)
1008   (ding))
1009
1010 (defun Info-help ()
1011   "Enter the Info tutorial."
1012   (interactive)
1013   (delete-other-windows)
1014   (Info-find-node "info"
1015                   (if (< (window-height) 23)
1016                       "Help-Small-Screen"
1017                     "Help")))
1018
1019 (defun Info-summary ()
1020   "Display a brief summary of all Info commands."
1021   (interactive)
1022   (save-window-excursion
1023     (switch-to-buffer "*Help*")
1024     (erase-buffer)
1025     (insert (documentation 'Info-mode))
1026     (goto-char (point-min))
1027     (let (ch flag)
1028       (while (progn (setq flag (not (pos-visible-in-window-p (point-max))))
1029                     (message (if flag "Type Space to see more"
1030                                "Type Space to return to Info"))
1031                     (if (not (eq ?\  (setq ch (read-event))))
1032                         (progn (setq unread-command-events (list ch)) nil)
1033                       flag))
1034         (scroll-up)))))
1035 \f
1036 (defun Info-get-token (pos start all &optional errorstring)
1037   "Return the token around POS,
1038 POS must be somewhere inside the token
1039 START is a regular expression which will match the
1040     beginning of the tokens delimited string
1041 ALL is a regular expression with a single
1042     parenthized subpattern which is the token to be
1043     returned. E.g. '{\(.*\)}' would return any string
1044     enclosed in braces around POS.
1045 SIG optional fourth argument, controls action on no match
1046     nil: return nil
1047     t: beep
1048     a string: signal an error, using that string."
1049   (save-excursion
1050     (goto-char pos)
1051     (re-search-backward start (max (point-min) (- pos 200)) 'yes)
1052     (while (and (re-search-forward all (min (point-max) (+ pos 200)) 'yes)
1053                 (not (and (<= (match-beginning 0) pos)
1054                           (> (match-end 0) pos)))))
1055     (if (and (<= (match-beginning 0) pos)
1056              (> (match-end 0) pos))
1057         (buffer-substring (match-beginning 1) (match-end 1))
1058       (cond ((null errorstring)
1059              nil)
1060             ((eq errorstring t)
1061              (beep)
1062              nil)
1063             (t
1064              (error "No %s around position %d" errorstring pos))))))
1065
1066 (defun Info-follow-nearest-node (click)
1067   "\\<Info-mode-map>Follow a node reference near point.
1068 Like \\[Info-menu], \\[Info-follow-reference], \\[Info-next], \\[Info-prev] or \\[Info-up] command, depending on where you click.
1069 At end of the node's text, moves to the next node."
1070   (interactive "e")
1071   (let* ((start (event-start click))
1072          (window (car start))
1073          (pos (car (cdr start))))
1074     (select-window window)
1075     (goto-char pos))
1076   (let (node)
1077     (cond
1078      ((setq node (Info-get-token (point) "\\*note[ \n]" "\\*note[ \n]\\([^:]*\\):" t))
1079       (Info-follow-reference node))
1080      ((setq node (Info-get-token (point) "\\* " "\\* \\([^:]*\\)::" t))
1081       (Info-goto-node node))
1082      ((setq node (Info-get-token (point) "\\* " "\\* \\([^:]*\\):" t))
1083       (Info-menu node))
1084      ((setq node (Info-get-token (point) "Up: " "Up: \\([^,\n\t]*\\)" t))
1085       (Info-goto-node node))
1086      ((setq node (Info-get-token (point) "Next: " "Next: \\([^,\n\t]*\\)" t))
1087       (Info-goto-node node))
1088      ((setq node (Info-get-token (point) "File: " "File: \\([^,\n\t]*\\)" t))
1089       (Info-goto-node "Top"))
1090      ((setq node (Info-get-token (point) "Prev: " "Prev: \\([^,\n\t]*\\)" t))
1091       (Info-goto-node node))
1092      ((save-excursion (forward-line 1) (eobp))
1093       (Info-next)))
1094     ))
1095 \f
1096 (defvar Info-mode-map nil
1097   "Keymap containing Info commands.")
1098 (if Info-mode-map
1099     nil
1100   (setq Info-mode-map (make-keymap))
1101   (suppress-keymap Info-mode-map)
1102   (define-key Info-mode-map "." 'beginning-of-buffer)
1103   (define-key Info-mode-map " " 'Info-scroll-up)
1104   (define-key Info-mode-map "\C-m" 'Info-next-preorder)
1105   (define-key Info-mode-map "1" 'Info-nth-menu-item)
1106   (define-key Info-mode-map "2" 'Info-nth-menu-item)
1107   (define-key Info-mode-map "3" 'Info-nth-menu-item)
1108   (define-key Info-mode-map "4" 'Info-nth-menu-item)
1109   (define-key Info-mode-map "5" 'Info-nth-menu-item)
1110   (define-key Info-mode-map "6" 'Info-nth-menu-item)
1111   (define-key Info-mode-map "7" 'Info-nth-menu-item)
1112   (define-key Info-mode-map "8" 'Info-nth-menu-item)
1113   (define-key Info-mode-map "9" 'Info-nth-menu-item)
1114   (define-key Info-mode-map "0" 'undefined)
1115   (define-key Info-mode-map "?" 'Info-summary)
1116   (define-key Info-mode-map "]" 'Info-forward-node)
1117   (define-key Info-mode-map "[" 'Info-backward-node)
1118   (define-key Info-mode-map "<" 'Info-top-node)
1119   (define-key Info-mode-map ">" 'Info-final-node)
1120   (define-key Info-mode-map "b" 'beginning-of-buffer)
1121   (define-key Info-mode-map "d" 'Info-directory)
1122   (define-key Info-mode-map "e" 'Info-edit)
1123   (define-key Info-mode-map "f" 'Info-follow-reference)
1124   (define-key Info-mode-map "g" 'Info-goto-node)
1125   (define-key Info-mode-map "h" 'Info-help)
1126   (define-key Info-mode-map "i" 'Info-index)
1127   (define-key Info-mode-map "l" 'Info-last)
1128   (define-key Info-mode-map "m" 'Info-menu)
1129   (define-key Info-mode-map "n" 'Info-next)
1130   (define-key Info-mode-map "p" 'Info-prev)
1131   (define-key Info-mode-map "q" 'Info-exit)
1132   (define-key Info-mode-map "s" 'Info-search)
1133   (define-key Info-mode-map "t" 'Info-top)
1134   (define-key Info-mode-map "u" 'Info-up)
1135   (define-key Info-mode-map "," 'Info-index-next)
1136   (define-key Info-mode-map "\177" 'Info-scroll-down)
1137   (define-key Info-mode-map [mouse-3] 'Info-follow-nearest-node)
1138   )
1139 \f
1140 ;; Info mode is suitable only for specially formatted data.
1141 (put 'info-mode 'mode-class 'special)
1142
1143 (defun Info-mode ()
1144   "\\<Info-mode-map>
1145 Info mode provides commands for browsing through the Info documentation tree.
1146 Documentation in Info is divided into \"nodes\", each of which discusses
1147 one topic and contains references to other nodes which discuss related
1148 topics.  Info has commands to follow the references and show you other nodes.
1149
1150 \\[Info-help]   Invoke the Info tutorial.
1151
1152 Selecting other nodes:
1153 \\[Info-next]   Move to the \"next\" node of this node.
1154 \\[Info-previous]       Move to the \"previous\" node of this node.
1155 \\[Info-up]     Move \"up\" from this node.
1156 \\[Info-menu]   Pick menu item specified by name (or abbreviation).
1157         Picking a menu item causes another node to be selected.
1158 \\[Info-directory]      Go to the Info directory node.
1159 \\[Info-follow-reference]       Follow a cross reference.  Reads name of reference.
1160 \\[Info-last]   Move to the last node you were at.
1161 \\[Info-index]  Look up a topic in this file's Index and move to that node.
1162 \\[Info-index-next]     (comma) Move to the next match from a previous `i' command.
1163
1164 Moving within a node:
1165 \\[scroll-up]   Normally, scroll forward a full screen.  If the end of the buffer is
1166 already visible, try to go to the next menu entry, or up if there is none.
1167 \\[scroll-down]  Normally, scroll backward.  If the beginning of the buffer is
1168 already visible, try to go to the previous menu entry, or up if there is none.
1169 \\[beginning-of-buffer] Go to beginning of node.
1170
1171 Advanced commands:
1172 \\[Info-exit]   Quit Info: reselect previously selected buffer.
1173 \\[Info-edit]   Edit contents of selected node.
1174 1       Pick first item in node's menu.
1175 2, 3, 4, 5   Pick second ... fifth item in node's menu.
1176 \\[Info-goto-node]      Move to node specified by name.
1177         You may include a filename as well, as (FILENAME)NODENAME.
1178 \\[Info-search] Search through this Info file for specified regexp,
1179         and select the node in which the next occurrence is found.
1180 \\[Info-next-preorder]  Next-preorder; that is, try to go to the next menu item,
1181         and if that fails try to move up, and if that fails, tell user
1182         he/she is done reading."
1183   (kill-all-local-variables)
1184   (setq major-mode 'Info-mode)
1185   (setq mode-name "Info")
1186   (use-local-map Info-mode-map)
1187   (set-syntax-table text-mode-syntax-table)
1188   (setq local-abbrev-table text-mode-abbrev-table)
1189   (setq case-fold-search t)
1190   (setq buffer-read-only t)
1191   (make-local-variable 'Info-current-file)
1192   (make-local-variable 'Info-current-subfile)
1193   (make-local-variable 'Info-current-node)
1194   (make-local-variable 'Info-tag-table-marker)
1195   (make-local-variable 'Info-history)
1196   (make-local-variable 'Info-index-alternatives)
1197   (Info-set-mode-line)
1198   (run-hooks 'Info-mode-hook))
1199
1200 (defvar Info-edit-map nil
1201   "Local keymap used within `e' command of Info.")
1202 (if Info-edit-map
1203     nil
1204   (setq Info-edit-map (nconc (make-sparse-keymap) text-mode-map))
1205   (define-key Info-edit-map "\C-c\C-c" 'Info-cease-edit))
1206
1207 ;; Info-edit mode is suitable only for specially formatted data.
1208 (put 'info-edit-mode 'mode-class 'special)
1209
1210 (defun Info-edit-mode ()
1211   "Major mode for editing the contents of an Info node.
1212 Like text mode with the addition of `Info-cease-edit'
1213 which returns to Info mode for browsing.
1214 \\{Info-edit-map}"
1215   )
1216
1217 (defun Info-edit ()
1218   "Edit the contents of this Info node.
1219 Allowed only if variable `Info-enable-edit' is non-nil."
1220   (interactive)
1221   (or Info-enable-edit
1222       (error "Editing info nodes is not enabled"))
1223   (use-local-map Info-edit-map)
1224   (setq major-mode 'Info-edit-mode)
1225   (setq mode-name "Info Edit")
1226   (kill-local-variable 'mode-line-buffer-identification)
1227   (setq buffer-read-only nil)
1228   ;; Make mode line update.
1229   (set-buffer-modified-p (buffer-modified-p))
1230   (message (substitute-command-keys
1231              "Editing: Type \\<info-mode-map>\\[Info-cease-edit] to return to info")))
1232
1233 (defun Info-cease-edit ()
1234   "Finish editing Info node; switch back to Info proper."
1235   (interactive)
1236   ;; Do this first, so nothing has changed if user C-g's at query.
1237   (and (buffer-modified-p)
1238        (y-or-n-p "Save the file? ")
1239        (save-buffer))
1240   (use-local-map Info-mode-map)
1241   (setq major-mode 'Info-mode)
1242   (setq mode-name "Info")
1243   (Info-set-mode-line)
1244   (setq buffer-read-only t)
1245   ;; Make mode line update.
1246   (set-buffer-modified-p (buffer-modified-p))
1247   (and (marker-position Info-tag-table-marker)
1248        (buffer-modified-p)
1249        (message "Tags may have changed.  Use Info-tagify if necessary")))
1250 \f
1251 (defun Info-find-emacs-command-nodes (command)
1252   "Return a list of locations documenting COMMAND in the Emacs Info manual.
1253 The locations are of the format used in Info-history, i.e.
1254 \(FILENAME NODENAME BUFFERPOS\)."
1255   (require 'info)
1256   (let ((where '())
1257         (cmd-desc (concat "^\\* " (regexp-quote (symbol-name command))
1258                           ":\\s *\\(.*\\)\\.$")))
1259     (save-excursion
1260       (Info-find-node "emacs" "Command Index")
1261       ;; Take the index node off the Info history.
1262       (setq Info-history (cdr Info-history))
1263       (goto-char (point-max))
1264       (while (re-search-backward cmd-desc nil t)
1265           (setq where (cons (list Info-current-file
1266                                   (buffer-substring
1267                                    (match-beginning 1)
1268                                    (match-end 1))
1269                                   0)
1270                             where)))
1271       where)))
1272
1273 ;;;###autoload
1274 (defun Info-goto-emacs-command-node (command)
1275   "Go to the Info node in the Emacs manual for command COMMAND."
1276   (interactive "CFind documentation for command: ")
1277   (or (commandp command)
1278       (signal 'wrong-type-argument (list 'commandp command)))
1279   (let ((where (Info-find-emacs-command-nodes command)))
1280     (if where
1281         (let ((num-matches (length where)))
1282           ;; Get Info running, and pop to it in another window.
1283           (save-window-excursion
1284             (info))
1285           (pop-to-buffer "*info*")
1286           (Info-find-node (car (car where))
1287                           (car (cdr (car where))))
1288           (if (> num-matches 1)
1289               (progn
1290                 ;; Info-find-node already pushed (car where) onto
1291                 ;; Info-history.  Put the other nodes that were found on
1292                 ;; the history.
1293                 (setq Info-history (nconc (cdr where) Info-history))
1294                 (message (substitute-command-keys
1295                           "Found %d other entr%.  Use \\[Info-last] to see %s."
1296                         (1- num-matches)
1297                         (if (> num-matches 2) "ies" "y")
1298                         (if (> num-matches 2) "them" "it"))))))
1299       (error "Couldn't find documentation for %s." command))))
1300
1301 ;;;###autoload
1302 (defun Info-goto-emacs-key-command-node (key)
1303   "Go to the Info node in the Emacs manual the command bound to KEY, a string.
1304 Interactively, if the binding is execute-extended-command, a command is read."
1305   (interactive "kFind documentation for key:")
1306   (let ((command (key-binding key)))
1307     (cond ((null command)
1308            (message "%s is undefined" (key-description key)))
1309           ((and (interactive-p)
1310                 (eq command 'execute-extended-command))
1311            (Info-goto-emacs-command-node
1312             (read-command "Find documentation for command: ")))
1313           (t
1314            (Info-goto-emacs-command-node command)))))
1315
1316 (provide 'info)
1317
1318 ;;; info.el ends here