lisp/info-look.el

   1 ;;; info-look.el --- major-mode-sensitive Info index lookup facility -*- lexical-binding: t -*-
   2 ;; An older version of this was known as libc.el.
   3
   4 ;; Copyright (C) 1995-1999, 2001-2015 Free Software Foundation, Inc.
   5
   6 ;; Author: Ralph Schleicher <rs@nunatak.allgaeu.org>
   7 ;;         (did not show signs of life (Nov 2001)  -stef)
   8 ;; Keywords: help languages
   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 ;; Really cool code to lookup info indexes.
  28 ;; Try especially info-lookup-symbol (aka C-h S).
  29
  30 ;; Some additional sources of (Tex)info files for non-GNU packages:
  31 ;;
  32 ;; Scheme: <URL:http://groups.csail.mit.edu/mac/ftpdir/scm/r5rs.info.tar.gz>
  33 ;; LaTeX:
  34 ;;  <URL:ftp://ctan.tug.org/tex-archive/info/latex2e-help-texinfo/latex2e.texi>
  35 ;;  (or CTAN mirrors)
  36 ;; Perl: <URL:ftp://ftp.cpan.org/pub/CPAN/doc/manual/texinfo/> (or CPAN mirrors)
  37
  38 ;; Traditionally, makeinfo quoted `like this', but version 5 and later
  39 ;; quotes 'like this' or ‘like this’.  Doc specs with patterns
  40 ;; therefore match open and close quotes with ['`‘] and ['’],
  41 ;; respectively.
  42
  43 ;;; Code:
  44
  45 (require 'info)
  46
  47 (defgroup info-lookup nil
  48   "Major mode sensitive help agent."
  49   :group 'help :group 'languages)
  50
  51 (defvar info-lookup-mode nil
  52   "Symbol of the current buffer's help mode.
  53 Help is provided according to the buffer's major mode if value is nil.
  54 Automatically becomes buffer local when set in any fashion.")
  55 (make-variable-buffer-local 'info-lookup-mode)
  56
  57 (defcustom info-lookup-other-window-flag t
  58   "Non-nil means pop up the Info buffer in another window."
  59   :group 'info-lookup :type 'boolean)
  60
  61 (defcustom info-lookup-highlight-face 'match
  62   "Face for highlighting looked up help items.
  63 Setting this variable to nil disables highlighting."
  64   :group 'info-lookup :type 'face)
  65
  66 (defvar info-lookup-highlight-overlay nil
  67   "Overlay object used for highlighting.")
  68
  69 (defcustom info-lookup-file-name-alist
  70   '(("\\`ac\\(local\\|site\\|include\\)\\.m4\\'" . autoconf-mode))
  71   "Alist of file names handled specially.
  72 List elements are cons cells of the form
  73
  74     (REGEXP . MODE)
  75
  76 If a file name matches REGEXP, then use help mode MODE instead of the
  77 buffer's major mode."
  78   :group 'info-lookup :type '(repeat (cons (string :tag "Regexp")
  79                                            (symbol :tag "Mode"))))
  80
  81 (defvar info-lookup-history nil
  82   "History of previous input lines.")
  83
  84 (defvar info-lookup-alist nil
  85   "Alist of known help topics.
  86 Cons cells are of the form
  87
  88     (HELP-TOPIC . HELP-DATA)
  89
  90 HELP-TOPIC is the symbol of a help topic.
  91 HELP-DATA is a HELP-TOPIC's public data set.
  92  Value is an alist with elements of the form
  93
  94     (HELP-MODE REGEXP IGNORE-CASE DOC-SPEC PARSE-RULE OTHER-MODES)
  95
  96 HELP-MODE is a mode's symbol.
  97 REGEXP is a regular expression matching those help items whose
  98  documentation can be looked up via DOC-SPEC.
  99 IGNORE-CASE is non-nil if help items are case insensitive.
 100 DOC-SPEC is a list of documentation specifications of the form
 101
 102     (INFO-NODE TRANS-FUNC PREFIX SUFFIX)
 103
 104 INFO-NODE is the name (including file name part) of an Info index.
 105 TRANS-FUNC is a function translating index entries into help items;
 106  nil means add only those index entries matching REGEXP, a string
 107  means prepend string to the first word of all index entries.
 108 PREFIX and SUFFIX are parts of a regular expression.  If one of
 109  them is non-nil then search the help item's Info node for the
 110  first occurrence of the regular expression `PREFIX ITEM SUFFIX'.
 111  ITEM will be highlighted with `info-lookup-highlight-face' if this
 112  variable is not nil.
 113 PARSE-RULE is either the symbol name of a function or a regular
 114  expression for guessing the default help item at point.  Fuzzy
 115  regular expressions like \"[_a-zA-Z0-9]+\" do a better job if
 116  there are no clear delimiters; do not try to write too complex
 117  expressions.  PARSE-RULE defaults to REGEXP.
 118 OTHER-MODES is a list of cross references to other help modes.")
 119
 120 (defsubst info-lookup->topic-value (topic)
 121   (cdr (assoc topic info-lookup-alist)))
 122
 123 (defsubst info-lookup->mode-value (topic mode)
 124   (assoc mode (info-lookup->topic-value topic)))
 125
 126 (defsubst info-lookup->regexp (topic mode)
 127   (nth 1 (info-lookup->mode-value topic mode)))
 128
 129 (defsubst info-lookup->ignore-case (topic mode)
 130   (nth 2 (info-lookup->mode-value topic mode)))
 131
 132 (defsubst info-lookup->doc-spec (topic mode)
 133   (nth 3 (info-lookup->mode-value topic mode)))
 134
 135 (defsubst info-lookup->parse-rule (topic mode)
 136   (nth 4 (info-lookup->mode-value topic mode)))
 137
 138 (defsubst info-lookup->other-modes (topic mode)
 139   (nth 5 (info-lookup->mode-value topic mode)))
 140
 141 (defun info-lookup-add-help (&rest arg)
 142   "Add or update a help specification.
 143 Function arguments are specified as keyword/argument pairs:
 144
 145     \(KEYWORD . ARGUMENT)
 146
 147 KEYWORD is either `:topic', `:mode', `:regexp', `:ignore-case',
 148  `:doc-spec', `:parse-rule', or `:other-modes'.
 149 ARGUMENT has a value as explained in the documentation of the
 150  variable `info-lookup-alist'.
 151
 152 If no topic or mode option has been specified, then the help topic defaults
 153 to `symbol', and the help mode defaults to the current major mode."
 154   (apply 'info-lookup-add-help* nil arg))
 155
 156 (defun info-lookup-maybe-add-help (&rest arg)
 157   "Add a help specification if none is defined.
 158 See the documentation of the function `info-lookup-add-help'
 159 for more details."
 160   (apply 'info-lookup-add-help* t arg))
 161
 162 (defun info-lookup-add-help* (maybe &rest arg)
 163   (let (topic mode regexp ignore-case doc-spec
 164               parse-rule other-modes keyword value)
 165     (setq topic 'symbol
 166           mode major-mode
 167           regexp "\\w+")
 168     (while arg
 169       (setq keyword (car arg))
 170       (or (symbolp keyword)
 171           (error "Junk in argument list \"%S\"" arg))
 172       (setq arg (cdr arg))
 173       (and (null arg)
 174            (error "Keyword \"%S\" is missing an argument" keyword))
 175       (setq value (car arg)
 176             arg (cdr arg))
 177       (cond ((eq keyword :topic)
 178              (setq topic value))
 179             ((eq keyword :mode)
 180              (setq mode value))
 181             ((eq keyword :regexp)
 182              (setq regexp value))
 183             ((eq keyword :ignore-case)
 184              (setq ignore-case value))
 185             ((eq keyword :doc-spec)
 186              (setq doc-spec value))
 187             ((eq keyword :parse-rule)
 188              (setq parse-rule value))
 189             ((eq keyword :other-modes)
 190              (setq other-modes value))
 191             (t
 192              (error "Unknown keyword \"%S\"" keyword))))
 193     (or (and maybe (info-lookup->mode-value topic mode))
 194         (let* ((data (list regexp ignore-case doc-spec parse-rule other-modes))
 195                (topic-cell (or (assoc topic info-lookup-alist)
 196                                (car (setq info-lookup-alist
 197                                           (cons (cons topic nil)
 198                                                 info-lookup-alist)))))
 199                (mode-cell (assoc mode topic-cell)))
 200           (if (null mode-cell)
 201               (setcdr topic-cell (cons (cons mode data) (cdr topic-cell)))
 202             (setcdr mode-cell data))))
 203     nil))
 204
 205 (defvar info-lookup-cache nil
 206   "Cache storing data maintained automatically by the program.
 207 Value is an alist with cons cell of the form
 208
 209     (HELP-TOPIC . ((HELP-MODE INITIALIZED COMPLETIONS REFER-MODES) ...))
 210
 211 HELP-TOPIC is the symbol of a help topic.
 212 HELP-MODE is a mode's symbol.
 213 INITIALIZED is nil if HELP-MODE is uninitialized, t if
 214  HELP-MODE is initialized, and `0' means HELP-MODE is
 215  initialized but void.
 216 COMPLETIONS is an alist of documented help items.
 217 REFER-MODES is a list of other help modes to use.")
 218
 219 (defsubst info-lookup->cache (topic)
 220   (or (assoc topic info-lookup-cache)
 221       (car (setq info-lookup-cache
 222                  (cons (cons topic nil)
 223                        info-lookup-cache)))))
 224
 225 (defun info-lookup->topic-cache (topic)
 226   (cdr (info-lookup->cache topic)))
 227
 228 (defun info-lookup->mode-cache (topic mode)
 229   (assoc mode (info-lookup->topic-cache topic)))
 230
 231 (defun info-lookup->initialized (topic mode)
 232   (nth 1 (info-lookup->mode-cache topic mode)))
 233
 234 (defun info-lookup->completions (topic mode)
 235   (or (info-lookup->initialized topic mode)
 236       (info-lookup-setup-mode topic mode))
 237   (nth 2 (info-lookup->mode-cache topic mode)))
 238
 239 (defun info-lookup->refer-modes (topic mode)
 240   (or (info-lookup->initialized topic mode)
 241       (info-lookup-setup-mode topic mode))
 242   (nth 3 (info-lookup->mode-cache topic mode)))
 243
 244 (defun info-lookup->all-modes (topic mode)
 245   (cons mode (info-lookup->refer-modes topic mode)))
 246
 247 (defun info-lookup-quick-all-modes (topic mode)
 248   (cons mode (info-lookup->other-modes topic mode)))
 249
 250 ;;;###autoload
 251 (defun info-lookup-reset ()
 252   "Throw away all cached data.
 253 This command is useful if the user wants to start at the beginning without
 254 quitting Emacs, for example, after some Info documents were updated on the
 255 system."
 256   (interactive)
 257   (setq info-lookup-cache nil))
 258
 259 ;;;###autoload (put 'info-lookup-symbol 'info-file "emacs")
 260 ;;;###autoload
 261 (defun info-lookup-symbol (symbol &optional mode)
 262   "Display the definition of SYMBOL, as found in the relevant manual.
 263 When this command is called interactively, it reads SYMBOL from the
 264 minibuffer.  In the minibuffer, use M-n to yank the default argument
 265 value into the minibuffer so you can edit it.  The default symbol is the
 266 one found at point.
 267
 268 With prefix arg MODE a query for the symbol help mode is offered."
 269   (interactive
 270    (info-lookup-interactive-arguments 'symbol current-prefix-arg))
 271   (info-lookup 'symbol symbol mode))
 272
 273 ;;;###autoload (put 'info-lookup-file 'info-file "emacs")
 274 ;;;###autoload
 275 (defun info-lookup-file (file &optional mode)
 276   "Display the documentation of a file.
 277 When this command is called interactively, it reads FILE from the minibuffer.
 278 In the minibuffer, use M-n to yank the default file name
 279 into the minibuffer so you can edit it.
 280 The default file name is the one found at point.
 281
 282 With prefix arg MODE a query for the file help mode is offered."
 283   (interactive
 284    (info-lookup-interactive-arguments 'file current-prefix-arg))
 285   (info-lookup 'file file mode))
 286
 287 (defun info-lookup-interactive-arguments (topic &optional query)
 288   "Read and return argument value (and help mode) for help topic TOPIC.
 289 If optional argument QUERY is non-nil, query for the help mode."
 290   (let* ((mode (cond (query
 291                       (info-lookup-change-mode topic))
 292                      ((info-lookup->mode-value topic (info-lookup-select-mode))
 293                       info-lookup-mode)
 294                      ((info-lookup-change-mode topic))))
 295          (completions (info-lookup->completions topic mode))
 296          (default (info-lookup-guess-default topic mode))
 297          (completion-ignore-case (info-lookup->ignore-case topic mode))
 298          (enable-recursive-minibuffers t)
 299          (value (completing-read
 300                  (if default
 301                      (format "Describe %s (default %s): " topic default)
 302                    (format "Describe %s: " topic))
 303                  completions nil nil nil 'info-lookup-history default)))
 304     (list (if (equal value "") default value) mode)))
 305
 306 (defun info-lookup-select-mode ()
 307   (when (and (not info-lookup-mode) (buffer-file-name))
 308     (let ((file-name (file-name-nondirectory (buffer-file-name)))
 309           (file-name-alist info-lookup-file-name-alist))
 310       (while (and (not info-lookup-mode) file-name-alist)
 311         (when (string-match (caar file-name-alist) file-name)
 312           (setq info-lookup-mode (cdar file-name-alist)))
 313         (setq file-name-alist (cdr file-name-alist)))))
 314
 315   ;; If major-mode has no setups in info-lookup-alist, under any topic, then
 316   ;; search up through derived-mode-parent to find a parent mode which does
 317   ;; have some setups.  This means that a `define-derived-mode' with no
 318   ;; setups of its own will select its parent mode for lookups, if one of
 319   ;; its parents has some setups.  Good for example on `makefile-gmake-mode'
 320   ;; and similar derivatives of `makefile-mode'.
 321   ;;
 322   (let ((mode major-mode)) ;; Look for `mode' with some setups.
 323     (while (and mode (not info-lookup-mode))
 324       (dolist (topic-cell info-lookup-alist) ;; Usually only two topics here.
 325         (if (info-lookup->mode-value (car topic-cell) mode)
 326             (setq info-lookup-mode mode)))
 327       (setq mode (get mode 'derived-mode-parent))))
 328
 329   (or info-lookup-mode (setq info-lookup-mode major-mode)))
 330
 331 (defun info-lookup-change-mode (topic)
 332   (let* ((completions (mapcar (lambda (arg)
 333                                 (cons (symbol-name (car arg)) (car arg)))
 334                               (info-lookup->topic-value topic)))
 335          (mode (completing-read
 336                 (format "Use %s help mode: " topic)
 337                 completions nil t nil 'info-lookup-history)))
 338     (or (setq mode (cdr (assoc mode completions)))
 339         (error "No %s help available" topic))
 340     (or (info-lookup->mode-value topic mode)
 341         (error "No %s help available for `%s'" topic mode))
 342     (setq info-lookup-mode mode)))
 343
 344 (defun info-lookup (topic item mode)
 345   "Display the documentation of a help item."
 346   (or mode (setq mode (info-lookup-select-mode)))
 347   (or (info-lookup->mode-value topic mode)
 348       (error "No %s help available for `%s'" topic mode))
 349   (let* ((completions (info-lookup->completions topic mode))
 350          (ignore-case (info-lookup->ignore-case topic mode))
 351          (entry (or (assoc (if ignore-case (downcase item) item) completions)
 352                     (assoc-string item completions t)
 353                     (error "Not documented as a %s: %s" topic (or item ""))))
 354          (modes (info-lookup->all-modes topic mode))
 355          (window (selected-window))
 356          (new-Info-history
 357           ;; Avoid clobbering Info-history with nodes searched during
 358           ;; lookup.  If lookup succeeds set `Info-history' to
 359           ;; `new-Info-history'.
 360           (when (get-buffer "*info*")
 361             (with-current-buffer "*info*"
 362               (cons (list Info-current-file Info-current-node (point))
 363                     Info-history))))
 364          found doc-spec node prefix suffix doc-found)
 365     (unless (eq major-mode 'Info-mode)
 366       (if (not info-lookup-other-window-flag)
 367           (info)
 368         (save-window-excursion (info))
 369         (let* ((info-window (get-buffer-window "*info*" t))
 370                (info-frame (and info-window (window-frame info-window))))
 371           (if (and info-frame
 372                    (not (eq info-frame (selected-frame)))
 373                    (display-multi-frame-p)
 374                    (memq info-frame (frames-on-display-list)))
 375               ;; *info* is visible in another frame on same display.
 376               ;; Raise that frame and select the window.
 377               (progn
 378                 (select-window info-window)
 379                 (raise-frame info-frame))
 380             ;; In any other case, switch to *info* in another window.
 381             (switch-to-buffer-other-window "*info*")))))
 382     (while (and (not found) modes)
 383       (setq doc-spec (info-lookup->doc-spec topic (car modes)))
 384       (while (and (not found) doc-spec)
 385         (setq node (nth 0 (car doc-spec))
 386               prefix (nth 2 (car doc-spec))
 387               suffix (nth 3 (car doc-spec)))
 388         (when (condition-case nil
 389                   (progn
 390                     ;; Don't need Index menu fontifications here, and
 391                     ;; they slow down the lookup.
 392                     (let (Info-fontify-maximum-menu-size
 393                           Info-history-list)
 394                       (Info-goto-node node)
 395                       (setq doc-found t)))
 396                 (error
 397                  (message "Cannot access Info node %s" node)
 398                  (sit-for 1)
 399                  nil))
 400           (condition-case nil
 401               (progn
 402                 ;; Don't use Info-menu, it forces case-fold-search to t
 403                 (let ((case-fold-search nil))
 404                   (re-search-forward
 405                    (concat "^\\* " (regexp-quote (or (cdr entry) (car entry)))
 406                            ":")))
 407                 (Info-follow-nearest-node)
 408                 (setq found t)
 409                 (if (or prefix suffix)
 410                     (let ((case-fold-search
 411                            (info-lookup->ignore-case topic (car modes)))
 412                           (buffer-read-only nil))
 413                       (goto-char (point-min))
 414                       (re-search-forward
 415                        (concat prefix (regexp-quote (car entry)) suffix))
 416                       (goto-char (match-beginning 0))
 417                       (and (display-color-p) info-lookup-highlight-face
 418                            ;; Search again for ITEM so that the first
 419                            ;; occurrence of ITEM will be highlighted.
 420                            (re-search-forward (regexp-quote (car entry)))
 421                            (let ((start (match-beginning 0))
 422                                  (end (match-end 0)))
 423                              (if (overlayp info-lookup-highlight-overlay)
 424                                  (move-overlay info-lookup-highlight-overlay
 425                                                start end (current-buffer))
 426                                (setq info-lookup-highlight-overlay
 427                                      (make-overlay start end))))
 428                            (overlay-put info-lookup-highlight-overlay
 429                                         'face info-lookup-highlight-face)))))
 430             (error nil)))
 431         (setq doc-spec (cdr doc-spec)))
 432       (setq modes (cdr modes)))
 433     ;; Alert the user if case was munged, and do this after bringing up the
 434     ;; info buffer since that can print messages
 435     (unless (or ignore-case
 436                 (string-equal item (car entry)))
 437       (message "Found in different case: %s" (car entry)))
 438     (when found
 439       (setq Info-history new-Info-history))
 440     (or doc-found
 441         (error "Info documentation for lookup was not found"))
 442     ;; Don't leave the Info buffer if the help item couldn't be looked up.
 443     (if (and info-lookup-other-window-flag found)
 444         (select-window window))))
 445
 446 (defun info-lookup-setup-mode (topic mode)
 447   "Initialize the internal data structure."
 448   (or (info-lookup->initialized topic mode)
 449       (let ((initialized 0)
 450             cell data completions refer-modes Info-history-list)
 451         (if (not (info-lookup->mode-value topic mode))
 452             (message "No %s help available for `%s'" topic mode)
 453           ;; Recursively setup cross references.
 454           ;; But refer only to non-void modes.
 455           (dolist (arg (info-lookup->other-modes topic mode))
 456             (or (info-lookup->initialized topic arg)
 457                 (info-lookup-setup-mode topic arg))
 458             (and (eq (info-lookup->initialized topic arg) t)
 459                  (setq refer-modes (cons arg refer-modes))))
 460           (setq refer-modes (nreverse refer-modes))
 461           ;; Build the full completion alist.
 462           (setq completions
 463                 (nconc (condition-case nil
 464                            (info-lookup-make-completions topic mode)
 465                          (error nil))
 466                        (apply 'append
 467                               (mapcar (lambda (arg)
 468                                         (info-lookup->completions topic arg))
 469                                       refer-modes))))
 470           (setq initialized t))
 471         ;; Update `info-lookup-cache'.
 472         (setq cell (info-lookup->mode-cache topic mode)
 473               data (list initialized completions refer-modes))
 474         (if (not cell)
 475             (setcdr (info-lookup->cache topic)
 476                     (cons (cons mode data) (info-lookup->topic-cache topic)))
 477           (setcdr cell data))
 478         initialized)))
 479
 480 (defun info-lookup-make-completions (topic mode)
 481   "Create a unique alist from all index entries."
 482   (let ((doc-spec (info-lookup->doc-spec topic mode))
 483         (regexp (concat "^\\(" (info-lookup->regexp topic mode)
 484                         "\\)\\([ \t].*\\)?$"))
 485         Info-history-list Info-fontify-maximum-menu-size
 486         node trans entry item prefix result doc-found
 487         (buffer (get-buffer-create " temp-info-look")))
 488     (with-current-buffer buffer
 489       (Info-mode))
 490     (while doc-spec
 491       (setq node (nth 0 (car doc-spec))
 492             trans (cond ((eq (nth 1 (car doc-spec)) nil)
 493                          (lambda (arg)
 494                            (if (string-match regexp arg)
 495                                (match-string 1 arg))))
 496                         ((stringp (nth 1 (car doc-spec)))
 497                          (setq prefix (nth 1 (car doc-spec)))
 498                          (lambda (arg)
 499                            (if (string-match "^\\([^: \t\n]+\\)" arg)
 500                                (concat prefix (match-string 1 arg)))))
 501                         (t (nth 1 (car doc-spec)))))
 502       (with-current-buffer buffer
 503         (message "Processing Info node `%s'..." node)
 504         (when (condition-case nil
 505                   (progn
 506                     (Info-goto-node node)
 507                     (setq doc-found t))
 508                 (error
 509                  (message "Cannot access Info node `%s'" node)
 510                  (sit-for 1)
 511                  nil))
 512           (condition-case nil
 513               (progn
 514                 (goto-char (point-min))
 515                 (and (search-forward "\n* Menu:" nil t)
 516                      (while (re-search-forward "\n\\* \\(.*\\): " nil t)
 517                        (setq entry (match-string 1)
 518                              item (funcall trans entry))
 519                        ;; `trans' can return nil if the regexp doesn't match.
 520                        (when (and item
 521                                   ;; Sometimes there's more than one Menu:
 522                                   (not (string= entry "Menu")))
 523                          (and (info-lookup->ignore-case topic mode)
 524                               (setq item (downcase item)))
 525                          (and (string-equal entry item)
 526                               (setq entry nil))
 527                          (and (or (assoc item result)
 528                                   (setq result (cons (cons item entry)
 529                                                      result))))))))
 530             (error nil))))
 531       (message "Processing Info node `%s'...done" node)
 532       (setq doc-spec (cdr doc-spec)))
 533     (or doc-found
 534         (error "Info documentation for lookup was not found"))
 535     result))
 536
 537 (defun info-lookup-guess-default (topic mode)
 538   "Return a guess for a symbol to look up, based on text around point.
 539 Try all related modes applicable to TOPIC and MODE.
 540 Return nil if there is nothing appropriate in the buffer near point."
 541   (let ((modes (info-lookup->all-modes topic mode))
 542         guess)
 543     (while (and (not guess) modes)
 544       (setq guess (info-lookup-guess-default* topic (car modes))
 545             modes (cdr modes)))
 546     ;; Collapse whitespace characters.
 547     (when guess
 548       (let ((pos 0))
 549         (while (string-match "[ \t\n]+" guess pos)
 550           (setq pos (1+ (match-beginning 0)))
 551           (setq guess (replace-match " " t t guess)))))
 552     guess))
 553
 554 (defun info-lookup-guess-default* (topic mode)
 555   (let ((case-fold-search (info-lookup->ignore-case topic mode))
 556         (rule (or (info-lookup->parse-rule topic mode)
 557                   (info-lookup->regexp topic mode)))
 558         (start (point)) end regexp subexp result)
 559     (save-excursion
 560       (if (symbolp rule)
 561           (setq result (funcall rule))
 562         (if (consp rule)
 563             (setq regexp (car rule)
 564                   subexp (cdr rule))
 565           (setq regexp rule
 566                 subexp 0))
 567         ;; If at start of symbol, don't go back to end of previous one.
 568         (if (save-match-data
 569               (looking-at "[ \t\n]"))
 570             (skip-chars-backward " \t\n"))
 571         (setq end (point))
 572         (while (and (re-search-backward regexp nil t)
 573                     (looking-at regexp)
 574                     (>= (match-end 0) end))
 575           (setq result (match-string subexp)))
 576         (if (not result)
 577             (progn
 578               (goto-char start)
 579               (skip-chars-forward " \t\n")
 580               (and (looking-at regexp)
 581                    (setq result (match-string subexp)))))))
 582     result))
 583
 584 (defun info-lookup-guess-c-symbol ()
 585   "Get the C symbol at point."
 586   (condition-case nil
 587       (progn
 588         (skip-syntax-backward "w_")
 589         (let ((start (point)) prefix name)
 590           ;; Test for a leading `struct', `union', or `enum' keyword
 591           ;; but ignore names like `foo_struct'.
 592           (setq prefix (and (< (skip-chars-backward " \t\n") 0)
 593                             (< (skip-chars-backward "_a-zA-Z0-9") 0)
 594                             (looking-at "\\(struct\\|union\\|enum\\)\\s ")
 595                             (concat (match-string 1) " ")))
 596           (goto-char start)
 597           (and (looking-at "[_a-zA-Z][_a-zA-Z0-9]*")
 598                (setq name (match-string 0)))
 599           ;; Caveat!  Look forward if point is at `struct' etc.
 600           (and (not prefix)
 601                (or (string-equal name "struct")
 602                    (string-equal name "union")
 603                    (string-equal name "enum"))
 604                (looking-at "[a-z]+\\s +\\([_a-zA-Z][_a-zA-Z0-9]*\\)")
 605                (setq prefix (concat name " ")
 606                      name (match-string 1)))
 607           (and (or prefix name)
 608                (concat prefix name))))
 609     (error nil)))
 610
 611 (defun info-lookup-guess-custom-symbol ()
 612   "Get symbol at point in custom buffers."
 613   (condition-case nil
 614       (save-excursion
 615         (let ((case-fold-search t)
 616               (ignored-chars "][()`'‘’,:.\" \t\n")
 617               (significant-chars "^][()`'‘’,:.\" \t\n")
 618               beg end)
 619           (cond
 620            ((and (memq (get-char-property (point) 'face)
 621                          '(custom-variable-tag custom-variable-tag-face))
 622                    (setq beg (previous-single-char-property-change
 623                               (point) 'face nil (line-beginning-position)))
 624                    (setq end (next-single-char-property-change
 625                               (point) 'face nil (line-end-position)))
 626                    (> end beg))
 627             (subst-char-in-string
 628              ?\s ?\- (buffer-substring-no-properties beg end)))
 629            ((or (and (looking-at (concat "[" significant-chars "]"))
 630                      (save-excursion
 631                        (skip-chars-backward significant-chars)
 632                        (setq beg (point)))
 633                      (skip-chars-forward significant-chars)
 634                      (setq end (point))
 635                      (> end beg))
 636                 (and (looking-at "[ \t\n]")
 637                      (looking-back (concat "[" significant-chars "]")
 638                                    (1- (point)))
 639                      (setq end (point))
 640                      (skip-chars-backward significant-chars)
 641                      (setq beg (point))
 642                      (> end beg))
 643                 (and (skip-chars-forward ignored-chars)
 644                      (setq beg (point))
 645                      (skip-chars-forward significant-chars)
 646                      (setq end (point))
 647                      (> end beg)))
 648             (buffer-substring-no-properties beg end)))))
 649     (error nil)))
 650
 651 ;;;###autoload
 652 (defun info-complete-symbol (&optional mode)
 653   "Perform completion on symbol preceding point."
 654   (interactive)
 655   (info-complete 'symbol
 656                  (or mode
 657                      (if (info-lookup->mode-value
 658                           'symbol (info-lookup-select-mode))
 659                          info-lookup-mode
 660                        (info-lookup-change-mode 'symbol)))))
 661
 662 ;;;###autoload
 663 (defun info-complete-file (&optional mode)
 664   "Perform completion on file preceding point."
 665   (interactive)
 666   (info-complete 'file
 667                  (or mode
 668                      (if (info-lookup->mode-value
 669                           'file (info-lookup-select-mode))
 670                          info-lookup-mode
 671                        (info-lookup-change-mode 'file)))))
 672
 673 (defun info-lookup-completions-at-point (topic mode)
 674   "Try to complete a help item."
 675   (or mode (setq mode (info-lookup-select-mode)))
 676   (when (info-lookup->mode-value topic mode)
 677     (let ((modes (info-lookup-quick-all-modes topic mode))
 678           (start (point))
 679           try)
 680       (while (and (not try) modes)
 681         (setq mode (car modes)
 682               modes (cdr modes)
 683               try (info-lookup-guess-default* topic mode))
 684         (goto-char start))
 685       (when try
 686         (let ((completions (info-lookup->completions topic mode)))
 687           (when completions
 688             (when (info-lookup->ignore-case topic mode)
 689               (setq completions
 690                     (lambda (string pred action)
 691                       (let ((completion-ignore-case t))
 692                         (complete-with-action
 693                          action completions string pred)))))
 694             (save-excursion
 695               ;; Find the original symbol and zap it.
 696               (end-of-line)
 697               (while (and (search-backward try nil t)
 698                           (< start (point))))
 699               (list (match-beginning 0) (match-end 0) completions
 700                     :exclusive 'no))))))))
 701
 702 (defun info-complete (topic mode)
 703   "Try to complete a help item."
 704   (barf-if-buffer-read-only)
 705   (let ((data (info-lookup-completions-at-point topic mode)))
 706     (if (null data)
 707         (error "No %s completion available for `%s' at point" topic mode)
 708       (completion-in-region (nth 0 data) (nth 1 data) (nth 2 data)))))
 709
 710 \f
 711 ;;; Initialize some common modes.
 712
 713 (info-lookup-maybe-add-help
 714  :mode 'c-mode :topic 'symbol
 715  :regexp "\\(struct \\|union \\|enum \\)?[_a-zA-Z][_a-zA-Z0-9]*"
 716  :doc-spec '(("(libc)Function Index" nil
 717               "^[ \t]+-+ \\(Function\\|Macro\\): .*\\<" "\\>")
 718              ;; prefix/suffix has to match things like
 719              ;;   " -- Macro: int F_DUPFD"
 720              ;;   " -- Variable: char * tzname [2]"
 721              ;;   "`DBL_MAX'"    (texinfo @table)
 722              ;; suffix "\\>" is not used because that sends DBL_MAX to
 723              ;; DBL_MAX_EXP ("_" is a non-word char)
 724              ("(libc)Variable Index" nil
 725               "^\\([ \t]+-+ \\(Variable\\|Macro\\): .*\\<\\|['`‘]\\)"
 726               "\\( \\|['’]?$\\)")
 727              ("(libc)Type Index" nil
 728               "^[ \t]+-+ Data Type: \\<" "\\>")
 729              ("(termcap)Var Index" nil
 730               "^[ \t]*['`‘]" "['’]"))
 731  :parse-rule 'info-lookup-guess-c-symbol)
 732
 733 (info-lookup-maybe-add-help
 734  :mode 'c-mode :topic 'file
 735  :regexp "[_a-zA-Z0-9./+-]+"
 736  :doc-spec '(("(libc)File Index")))
 737
 738 (info-lookup-maybe-add-help
 739  :mode 'bison-mode
 740  :regexp "[:;|]\\|%\\([%{}]\\|[_a-z]+\\)\\|YY[_A-Z]+\\|yy[_a-z]+"
 741  :doc-spec '(("(bison)Index" nil
 742               "['`‘]" "['’]"))
 743  :parse-rule "[:;|]\\|%\\([%{}]\\|[_a-zA-Z][_a-zA-Z0-9]*\\)"
 744  :other-modes '(c-mode))
 745
 746 (info-lookup-maybe-add-help
 747  :mode 'makefile-mode
 748  :regexp "\\$[^({]\\|\\.[_A-Z]*\\|[_a-zA-Z][_a-zA-Z0-9-]*"
 749  :doc-spec '(("(make)Name Index" nil
 750               "^[ \t]*['`‘]" "['’]"))
 751  :parse-rule "\\$[^({]\\|\\.[_A-Z]*\\|[_a-zA-Z0-9-]+")
 752
 753 (info-lookup-maybe-add-help
 754  :topic      'symbol
 755  :mode       'makefile-automake-mode
 756  ;; similar regexp/parse-rule as makefile-mode, but also the following
 757  ;; (which have index entries),
 758  ;;   "##" special automake comment
 759  ;;   "+=" append operator, separate from the GNU make one
 760  :regexp     "\\$[^({]\\|\\.[_A-Z]*\\|[_a-zA-Z][_a-zA-Z0-9-]*\\|##\\|\\+="
 761  :parse-rule "\\$[^({]\\|\\.[_A-Z]*\\|[_a-zA-Z0-9-]+\\|##\\|\\+="
 762  :doc-spec   '(
 763                ;; "(automake)Macro Index" is autoconf macros used in
 764                ;; configure.ac, not Makefile.am, so don't have that here.
 765                ("(automake)Variable Index" nil "^[ \t]*['`‘]" "['’]")
 766                ;; In automake 1.4 macros and variables were a combined node.
 767                ("(automake)Macro and Variable Index" nil "^[ \t]*['`‘]"
 768                 "['’]")
 769                ;; Directives like "if" are in the "General Index".
 770                ;; Prefix "`" since the text for say `+=' isn't always an
 771                ;; @item etc and so not always at the start of a line.
 772                ("(automake)General Index" nil "['`‘]" "['’]")
 773                ;; In automake 1.3 there was just a single "Index" node.
 774                ("(automake)Index" nil "['`‘]" "['’]"))
 775  :other-modes '(makefile-mode))
 776
 777 (info-lookup-maybe-add-help
 778  :mode 'texinfo-mode
 779  :regexp "@\\([a-zA-Z]+\\|[^a-zA-Z]\\)"
 780  :doc-spec '(("(texinfo)Command and Variable Index"
 781               ;; Ignore Emacs commands and prepend a `@'.
 782               (lambda (item)
 783                 (if (string-match "^\\([a-zA-Z]+\\|[^a-zA-Z]\\)\\( .*\\)?$" item)
 784                     (concat "@" (match-string 1 item))))
 785               "['`‘]" "['’ ]")))
 786
 787 (info-lookup-maybe-add-help
 788  :mode 'm4-mode
 789  :regexp "[_a-zA-Z][_a-zA-Z0-9]*"
 790  :doc-spec '(("(m4)Macro index"))
 791  :parse-rule "[_a-zA-Z0-9]+")
 792
 793 (info-lookup-maybe-add-help
 794  :mode 'autoconf-mode
 795  :regexp "A[CM]_[_A-Z0-9]+"
 796  :doc-spec '(;; Autoconf Macro Index entries are without an "AC_" prefix,
 797              ;; but with "AH_" or "AU_" for those.  So add "AC_" if there
 798              ;; isn't already an "A._".
 799              ("(autoconf)Autoconf Macro Index"
 800               (lambda (item)
 801                 (if (string-match "^A._" item) item (concat "AC_" item)))
 802               "^[ \t]+-+ \\(Macro\\|Variable\\): .*\\<" "\\>")
 803              ;; M4 Macro Index entries are without "AS_" prefixes, and
 804              ;; mostly without "m4_" prefixes.  "dnl" is an exception, not
 805              ;; wanting any prefix.  So AS_ is added back to upper-case
 806              ;; names (if needed), m4_ to others which don't already an m4_.
 807              ("(autoconf)M4 Macro Index"
 808               (lambda (item)
 809                 (let ((case-fold-search nil))
 810                   (cond ((or (string-equal item "dnl")
 811                              (string-match "^m4_" item)
 812                              ;; Autoconf 2.62 index includes some macros
 813                              ;; (e.g., AS_HELP_STRING), so avoid prefixing.
 814                              (string-match "^AS_" item))
 815                          item)
 816                         ((string-match "^[A-Z0-9_]+$" item)
 817                          (concat "AS_" item))
 818                         (t
 819                          (concat "m4_" item)))))
 820               "^[ \t]+-+ Macro: .*\\<" "\\>")
 821              ;; Autotest Macro Index entries are without "AT_".
 822              ("(autoconf)Autotest Macro Index" "AT_"
 823               "^[ \t]+-+ Macro: .*\\<" "\\>")
 824              ;; This is for older versions (probably pre autoconf 2.5x):
 825              ("(autoconf)Macro Index" "AC_"
 826               "^[ \t]+-+ \\(Macro\\|Variable\\): .*\\<" "\\>")
 827              ;; Automake has index entries for its notes on various autoconf
 828              ;; macros (eg. AC_PROG_CC).  Ensure this is after the autoconf
 829              ;; index, so as to prefer the autoconf docs.
 830              ("(automake)Macro and Variable Index" nil
 831               "^[ \t]*['`‘]" "['’]"))
 832  ;; Autoconf symbols are M4 macros.  Thus use M4's parser.
 833  :parse-rule 'ignore
 834  :other-modes '(m4-mode))
 835
 836 (info-lookup-maybe-add-help
 837  :mode 'awk-mode
 838  :regexp "[_a-zA-Z]+"
 839  :doc-spec '(("(gawk)Index"
 840               (lambda (item)
 841                 (let ((case-fold-search nil))
 842                   (cond
 843                    ;; `BEGIN' and `END'.
 844                    ((string-match "^\\([A-Z]+\\) special pattern\\b" item)
 845                     (match-string 1 item))
 846                    ;; `if', `while', `do', ...
 847                    ((string-match "^\\([a-z]+\\) statement\\b" item)
 848                     (if (not (string-equal (match-string 1 item) "control"))
 849                         (match-string 1 item)))
 850                    ;; `NR', `NF', ...
 851                    ((string-match "^[A-Z]+$" item)
 852                     item)
 853                    ;; Built-in functions (matches to many entries).
 854                    ((string-match "^[a-z]+$" item)
 855                     item))))
 856               "['`‘]" "\\([ \t]*([^)]*)\\)?['’]")))
 857
 858 (info-lookup-maybe-add-help
 859  :mode 'perl-mode
 860  :regexp "[$@%][^a-zA-Z]\\|\\$\\^[A-Z]\\|[$@%]?[a-zA-Z][_a-zA-Z0-9]*"
 861  :doc-spec '(("(perl5)Function Index"
 862               (lambda (item)
 863                 (if (string-match "^\\([a-zA-Z0-9]+\\)" item)
 864                     (match-string 1 item)))
 865               "^" "\\b")
 866              ("(perl5)Variable Index"
 867               (lambda (item)
 868                 ;; Work around bad formatted array variables.
 869                 (let ((sym (cond ((or (string-match "^\\$\\(.\\|@@\\)$" item)
 870                                       (string-match "^\\$\\^[A-Z]$" item))
 871                                   item)
 872                                  ((string-match
 873                                    "^\\([$%@]\\|@@\\)?[_a-zA-Z0-9]+" item)
 874                                   (match-string 0 item))
 875                                  (t ""))))
 876                   (if (string-match "@@" sym)
 877                       (setq sym (concat (substring sym 0 (match-beginning 0))
 878                                         (substring sym (1- (match-end 0))))))
 879                   (if (string-equal sym "") nil sym)))
 880               "^" "\\b"))
 881  :parse-rule "[$@%]?\\([_a-zA-Z0-9]+\\|[^a-zA-Z]\\)")
 882
 883 (info-lookup-maybe-add-help
 884  :mode 'cperl-mode
 885  :regexp "[$@%][^a-zA-Z]\\|\\$\\^[A-Z]\\|[$@%]?[a-zA-Z][_a-zA-Z0-9]*"
 886  :other-modes '(perl-mode))
 887
 888 (info-lookup-maybe-add-help
 889  :mode 'latex-mode
 890  :regexp "\\\\\\([a-zA-Z]+\\|[^a-zA-Z]\\)"
 891  :doc-spec `((,(if (Info-find-file "latex2e" t)
 892                    ;; From http://home.gna.org/latexrefman
 893                    "(latex2e)Command Index"
 894                  "(latex)Command Index")
 895               ;; \frac{NUM}{DEN} etc can have more than one {xx} argument.
 896               ;; \sqrt[ROOT]{num} and others can have square brackets.
 897               nil "[`'‘]" "\\({[^}]*}|\\[[^]]*\\]\\)*['’]")))
 898
 899
 900 (info-lookup-maybe-add-help
 901  :mode 'emacs-lisp-mode
 902  :regexp "[^][()`'‘’,\" \t\n]+"
 903  :doc-spec '(;; Commands with key sequences appear in nodes as `foo' and
 904              ;; those without as `M-x foo'.
 905              ("(emacs)Command Index"  nil "['`‘]\\(M-x[ \t\n]+\\)?" "['’]")
 906              ;; Variables normally appear in nodes as just `foo'.
 907              ("(emacs)Variable Index" nil "['`‘]" "['’]")
 908              ;; Almost all functions, variables, etc appear in nodes as
 909              ;; " -- Function: foo" etc.  A small number of aliases and
 910              ;; symbols appear only as `foo', and will miss out on exact
 911              ;; positions.  Allowing `foo' would hit too many false matches
 912              ;; for things that should go to Function: etc, and those latter
 913              ;; are much more important.  Perhaps this could change if some
 914              ;; sort of fallback match scheme existed.
 915              ("(elisp)Index"          nil "^ -+ .*: " "\\( \\|$\\)")))
 916
 917 ;; docstrings talk about elisp, so have apropos-mode follow emacs-lisp-mode
 918 (info-lookup-maybe-add-help
 919  :mode 'apropos-mode
 920  :regexp "[^][()`'‘’,\" \t\n]+" ;; same as emacs-lisp-mode above
 921  :other-modes '(emacs-lisp-mode))
 922
 923 (info-lookup-maybe-add-help
 924  :mode 'lisp-interaction-mode
 925  :regexp "[^][()`'‘’,\" \t\n]+"
 926  :parse-rule 'ignore
 927  :other-modes '(emacs-lisp-mode))
 928
 929 (info-lookup-maybe-add-help
 930  :mode 'lisp-mode
 931  :regexp "[^()`'‘’,\" \t\n]+"
 932  :parse-rule 'ignore
 933  :other-modes '(emacs-lisp-mode))
 934
 935 (info-lookup-maybe-add-help
 936  :mode 'scheme-mode
 937  :regexp "[^()`'‘’,\" \t\n]+"
 938  :ignore-case t
 939  ;; Aubrey Jaffer's rendition from <URL:ftp://ftp-swiss.ai.mit.edu/pub/scm>
 940  :doc-spec '(("(r5rs)Index" nil
 941               "^[ \t]+-+ [^:]+:[ \t]*" "\\b")))
 942
 943 (info-lookup-maybe-add-help
 944  :mode 'octave-mode
 945  :regexp "[_a-zA-Z0-9]+\\|\\s.+\\|[-!=^|*/.\\,><~&+]\\{1,3\\}\\|[][();,\"']"
 946  :doc-spec '(("(octave)Function Index" nil
 947               "^ -+ [^:]+:[ ]+\\(\\[[^=]*=[ ]+\\)?" nil)
 948              ("(octave)Variable Index" nil "^ -+ [^:]+:[ ]+" nil)
 949              ("(octave)Operator Index" nil nil nil)
 950              ;; Catch lines of the form "xyz statement"
 951              ("(octave)Concept Index"
 952               (lambda (item)
 953                 (cond
 954                  ((string-match "^\\([A-Z]+\\) statement\\b" item)
 955                     (match-string 1 item))
 956                  (t nil)))
 957               nil; "^ -+ [^:]+:[ ]+" don't think this prefix is useful here.
 958               nil)))
 959
 960 (info-lookup-maybe-add-help
 961  :mode 'maxima-mode
 962  :ignore-case t
 963  :regexp "[a-zA-Z0-9_%]+"
 964  :doc-spec '( ("(maxima)Function and Variable Index" nil
 965                "^ -+ [^:]+:[ ]+\\(\\[[^=]*=[ ]+\\)?" nil)))
 966
 967 (info-lookup-maybe-add-help
 968  :mode 'inferior-maxima-mode
 969  :regexp "[a-zA-Z0-9_%]+"
 970  :other-modes '(maxima-mode))
 971
 972 ;; coreutils and bash builtins overlap in places, eg. printf, so there's a
 973 ;; question which should come first.  Some of the coreutils descriptions are
 974 ;; more detailed, but if bash is usually /bin/sh on a GNU system then the
 975 ;; builtins will be what's normally run.
 976 ;;
 977 ;; Maybe special variables like $? should be matched as $?, not just ?.
 978 ;; This would avoid a clash between variable $! and negation !, or variable
 979 ;; $# and comment # (though comment # is not currently indexed in bash).
 980 ;; Unfortunately if $? etc is the symbol, then we wouldn't be taken to the
 981 ;; exact spot in the relevant node, since the bash manual has just `?' etc
 982 ;; there.  Maybe an extension to the prefix/suffix scheme could help this.
 983
 984 (info-lookup-maybe-add-help
 985  :mode 'sh-mode :topic 'symbol
 986  ;; bash has "." and ":" in its index, but those chars will probably never
 987  ;; work in info, so don't bother matching them in the regexp.
 988  :regexp "\\([a-zA-Z0-9_-]+\\|[!{}@*#?$]\\|\\[\\[?\\|]]?\\)"
 989  :doc-spec '(("(bash)Builtin Index"       nil "^['`‘]" "[ .'’]")
 990              ("(bash)Reserved Word Index" nil "^['`‘]" "[ .'’]")
 991              ("(bash)Variable Index"      nil "^['`‘]" "[ .'’]")
 992
 993              ;; coreutils (version 4.5.10) doesn't have a separate program
 994              ;; index, so exclude extraneous stuff (most of it) by demanding
 995              ;; "[a-z]+" in the trans-func.
 996              ;; coreutils version 8.1 has node "Concept Index" and past
 997              ;; versions have node "Index", look for both, whichever is
 998              ;; absent is quietly ignored
 999              ("(coreutils)Index"
1000               (lambda (item) (if (string-match "\\`[a-z]+\\'" item) item)))
1001              ("(coreutils)Concept Index"
1002               (lambda (item) (if (string-match "\\`[a-z]+\\'" item) item)))
1003
1004              ;; diff (version 2.8.1) has only a few programs, index entries
1005              ;; are things like "foo invocation".
1006              ("(diff)Index"
1007               (lambda (item)
1008                 (if (string-match "\\`\\([a-z]+\\) invocation\\'" item)
1009                     (match-string 1 item))))
1010              ;; there's no plain "sed" index entry as such, mung another
1011              ;; hopefully unique one to get to the invocation section
1012              ("(sed)Concept Index"
1013               (lambda (item)
1014                 (if (string-equal item "Standard input, processing as input")
1015                     "sed")))
1016              ;; there's no plain "awk" or "gawk" index entries, mung other
1017              ;; hopefully unique ones to get to the command line options
1018              ("(gawk)Index"
1019               (lambda (item)
1020                 (cond ((string-equal item "gawk, extensions, disabling")
1021                        "awk")
1022                       ((string-equal item "gawk, versions of, information about, printing")
1023                        "gawk"))))))
1024
1025 ;; This misses some things which occur as node names but not in the
1026 ;; index.  Unfortunately it also picks up the wrong one of multiple
1027 ;; entries for the same term in some cases.  --fx
1028 (info-lookup-maybe-add-help
1029  :mode 'cfengine-mode
1030  :regexp "[[:alnum:]_]+\\(?:()\\)?"
1031  :doc-spec '(("(cfengine-Reference)Variable Index"
1032               (lambda (item)
1033                 ;; Index entries may be like `IsPlain()'
1034                 (if (string-match "\\([[:alnum:]_]+\\)()" item)
1035                     (match-string 1 item)
1036                   item))
1037               ;; This gets functions in evaluated classes.  Other
1038               ;; possible patterns don't seem to work too well.
1039               "['`‘]" "(")))
1040
1041 (info-lookup-maybe-add-help
1042  :mode 'Custom-mode
1043  :ignore-case t
1044  :regexp "[^][()`'‘’,:\" \t\n]+"
1045  :parse-rule 'info-lookup-guess-custom-symbol
1046  :other-modes '(emacs-lisp-mode))
1047
1048 (info-lookup-maybe-add-help
1049  :mode 'help-mode
1050  :regexp "[^][()`'‘’,:\" \t\n]+"
1051  :other-modes '(emacs-lisp-mode))
1052 \f
1053 (provide 'info-look)
1054
1055 ;;; info-look.el ends here