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, 2001-2017 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 <https://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:http://ctan.tug.org/tex-archive/info/latex2e-help-texinfo/latex2e.texi>
  35 ;;  (or CTAN mirrors)
  36 ;; Perl: <URL:http://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 (eval-when-compile (require 'subr-x))
  47
  48 (defgroup info-lookup nil
  49   "Major mode sensitive help agent."
  50   :group 'help :group 'languages)
  51
  52 (defvar info-lookup-mode nil
  53   "Symbol of the current buffer's help mode.
  54 Help is provided according to the buffer's major mode if value is nil.
  55 Automatically becomes buffer local when set in any fashion.")
  56 (make-variable-buffer-local 'info-lookup-mode)
  57
  58 (defcustom info-lookup-other-window-flag t
  59   "Non-nil means pop up the Info buffer in another window."
  60   :group 'info-lookup :type 'boolean)
  61
  62 (defcustom info-lookup-highlight-face 'match
  63   "Face for highlighting looked up help items.
  64 Setting this variable to nil disables highlighting."
  65   :group 'info-lookup :type 'face)
  66
  67 (defvar info-lookup-highlight-overlay nil
  68   "Overlay object used for highlighting.")
  69
  70 (defcustom info-lookup-file-name-alist
  71   '(("\\`ac\\(local\\|site\\|include\\)\\.m4\\'" . autoconf-mode))
  72   "Alist of file names handled specially.
  73 List elements are cons cells of the form
  74
  75     (REGEXP . MODE)
  76
  77 If a file name matches REGEXP, then use help mode MODE instead of the
  78 buffer's major mode."
  79   :group 'info-lookup :type '(repeat (cons (string :tag "Regexp")
  80                                            (symbol :tag "Mode"))))
  81
  82 (defvar info-lookup-history nil
  83   "History of previous input lines.")
  84
  85 (defvar info-lookup-alist nil
  86   "Alist of known help topics.
  87 Cons cells are of the form
  88
  89     (HELP-TOPIC . HELP-DATA)
  90
  91 HELP-TOPIC is the symbol of a help topic.
  92 HELP-DATA is a HELP-TOPIC's public data set.
  93  Value is an alist with elements of the form
  94
  95     (HELP-MODE REGEXP IGNORE-CASE DOC-SPEC PARSE-RULE OTHER-MODES)
  96
  97 HELP-MODE is a mode's symbol.
  98 REGEXP is a regular expression matching those help items whose
  99  documentation can be looked up via DOC-SPEC.
 100 IGNORE-CASE is non-nil if help items are case insensitive.
 101 DOC-SPEC is a list of documentation specifications of the form
 102
 103     (INFO-NODE TRANS-FUNC PREFIX SUFFIX)
 104
 105 INFO-NODE is the name (including file name part) of an Info index.
 106 TRANS-FUNC is a function translating index entries into help items;
 107  nil means add only those index entries matching REGEXP, a string
 108  means prepend string to the first word of all index entries.
 109 PREFIX and SUFFIX are parts of a regular expression.  If one of
 110  them is non-nil then search the help item's Info node for the
 111  first occurrence of the regular expression `PREFIX ITEM SUFFIX'.
 112  ITEM will be highlighted with `info-lookup-highlight-face' if this
 113  variable is not nil.
 114 PARSE-RULE is either the symbol name of a function or a regular
 115  expression for guessing the default help item at point.  Fuzzy
 116  regular expressions like \"[_a-zA-Z0-9]+\" do a better job if
 117  there are no clear delimiters; do not try to write too complex
 118  expressions.  PARSE-RULE defaults to REGEXP.
 119 OTHER-MODES is a list of cross references to other help modes.")
 120
 121 (defsubst info-lookup->topic-value (topic)
 122   (cdr (assoc topic info-lookup-alist)))
 123
 124 (defsubst info-lookup->mode-value (topic mode)
 125   (assoc mode (info-lookup->topic-value topic)))
 126
 127 (defsubst info-lookup->regexp (topic mode)
 128   (nth 1 (info-lookup->mode-value topic mode)))
 129
 130 (defsubst info-lookup->ignore-case (topic mode)
 131   (nth 2 (info-lookup->mode-value topic mode)))
 132
 133 (defsubst info-lookup->doc-spec (topic mode)
 134   (nth 3 (info-lookup->mode-value topic mode)))
 135
 136 (defsubst info-lookup->parse-rule (topic mode)
 137   (nth 4 (info-lookup->mode-value topic mode)))
 138
 139 (defsubst info-lookup->other-modes (topic mode)
 140   (nth 5 (info-lookup->mode-value topic mode)))
 141
 142 (defun info-lookup-add-help (&rest arg)
 143   "Add or update a help specification.
 144 Function arguments are specified as keyword/argument pairs:
 145
 146     (KEYWORD . ARGUMENT)
 147
 148 KEYWORD is either `:topic', `:mode', `:regexp', `:ignore-case',
 149  `:doc-spec', `:parse-rule', or `:other-modes'.
 150 ARGUMENT has a value as explained in the documentation of the
 151  variable `info-lookup-alist'.
 152
 153 If no topic or mode option has been specified, then the help topic defaults
 154 to `symbol', and the help mode defaults to the current major mode."
 155   (apply 'info-lookup-add-help* nil arg))
 156
 157 (defun info-lookup-maybe-add-help (&rest arg)
 158   "Add a help specification if none is defined.
 159 See the documentation of the function `info-lookup-add-help'
 160 for more details."
 161   (apply 'info-lookup-add-help* t arg))
 162
 163 (defun info-lookup-add-help* (maybe &rest arg)
 164   (let (topic mode regexp ignore-case doc-spec
 165               parse-rule other-modes keyword value)
 166     (setq topic 'symbol
 167           mode major-mode
 168           regexp "\\w+")
 169     (while arg
 170       (setq keyword (car arg))
 171       (or (symbolp keyword)
 172           (error "Junk in argument list \"%S\"" arg))
 173       (setq arg (cdr arg))
 174       (and (null arg)
 175            (error "Keyword \"%S\" is missing an argument" keyword))
 176       (setq value (car arg)
 177             arg (cdr arg))
 178       (cond ((eq keyword :topic)
 179              (setq topic value))
 180             ((eq keyword :mode)
 181              (setq mode value))
 182             ((eq keyword :regexp)
 183              (setq regexp value))
 184             ((eq keyword :ignore-case)
 185              (setq ignore-case value))
 186             ((eq keyword :doc-spec)
 187              (setq doc-spec value))
 188             ((eq keyword :parse-rule)
 189              (setq parse-rule value))
 190             ((eq keyword :other-modes)
 191              (setq other-modes value))
 192             (t
 193              (error "Unknown keyword \"%S\"" keyword))))
 194     (or (and maybe (info-lookup->mode-value topic mode))
 195         (let* ((data (list regexp ignore-case doc-spec parse-rule other-modes))
 196                (topic-cell (or (assoc topic info-lookup-alist)
 197                                (car (setq info-lookup-alist
 198                                           (cons (cons topic nil)
 199                                                 info-lookup-alist)))))
 200                (mode-cell (assoc mode topic-cell)))
 201           (if (null mode-cell)
 202               (setcdr topic-cell (cons (cons mode data) (cdr topic-cell)))
 203             (setcdr mode-cell data))))
 204     nil))
 205
 206 (defvar info-lookup-cache nil
 207   "Cache storing data maintained automatically by the program.
 208 Value is an alist with cons cell of the form
 209
 210     (HELP-TOPIC . ((HELP-MODE INITIALIZED COMPLETIONS REFER-MODES) ...))
 211
 212 HELP-TOPIC is the symbol of a help topic.
 213 HELP-MODE is a mode's symbol.
 214 INITIALIZED is nil if HELP-MODE is uninitialized, t if
 215  HELP-MODE is initialized, and `0' means HELP-MODE is
 216  initialized but void.
 217 COMPLETIONS is an alist of documented help items.
 218 REFER-MODES is a list of other help modes to use.")
 219
 220 (defsubst info-lookup->cache (topic)
 221   (or (assoc topic info-lookup-cache)
 222       (car (setq info-lookup-cache
 223                  (cons (cons topic nil)
 224                        info-lookup-cache)))))
 225
 226 (defun info-lookup->topic-cache (topic)
 227   (cdr (info-lookup->cache topic)))
 228
 229 (defun info-lookup->mode-cache (topic mode)
 230   (assoc mode (info-lookup->topic-cache topic)))
 231
 232 (defun info-lookup->initialized (topic mode)
 233   (nth 1 (info-lookup->mode-cache topic mode)))
 234
 235 (defun info-lookup->completions (topic mode)
 236   (or (info-lookup->initialized topic mode)
 237       (info-lookup-setup-mode topic mode))
 238   (nth 2 (info-lookup->mode-cache topic mode)))
 239
 240 (defun info-lookup->refer-modes (topic mode)
 241   (or (info-lookup->initialized topic mode)
 242       (info-lookup-setup-mode topic mode))
 243   (nth 3 (info-lookup->mode-cache topic mode)))
 244
 245 (defun info-lookup->all-modes (topic mode)
 246   (cons mode (info-lookup->refer-modes topic mode)))
 247
 248 (defun info-lookup-quick-all-modes (topic mode)
 249   (cons mode (info-lookup->other-modes topic mode)))
 250
 251 ;;;###autoload
 252 (defun info-lookup-reset ()
 253   "Throw away all cached data.
 254 This command is useful if the user wants to start at the beginning without
 255 quitting Emacs, for example, after some Info documents were updated on the
 256 system."
 257   (interactive)
 258   (setq info-lookup-cache nil))
 259
 260 ;;;###autoload (put 'info-lookup-symbol 'info-file "emacs")
 261 ;;;###autoload
 262 (defun info-lookup-symbol (symbol &optional mode)
 263   "Display the definition of SYMBOL, as found in the relevant manual.
 264 When this command is called interactively, it reads SYMBOL from the
 265 minibuffer.  In the minibuffer, use M-n to yank the default argument
 266 value into the minibuffer so you can edit it.  The default symbol is the
 267 one found at point.
 268
 269 With prefix arg MODE a query for the symbol help mode is offered."
 270   (interactive
 271    (info-lookup-interactive-arguments 'symbol current-prefix-arg))
 272   (info-lookup 'symbol symbol mode))
 273
 274 ;;;###autoload (put 'info-lookup-file 'info-file "emacs")
 275 ;;;###autoload
 276 (defun info-lookup-file (file &optional mode)
 277   "Display the documentation of a file.
 278 When this command is called interactively, it reads FILE from the minibuffer.
 279 In the minibuffer, use M-n to yank the default file name
 280 into the minibuffer so you can edit it.
 281 The default file name is the one found at point.
 282
 283 With prefix arg MODE a query for the file help mode is offered."
 284   (interactive
 285    (info-lookup-interactive-arguments 'file current-prefix-arg))
 286   (info-lookup 'file file mode))
 287
 288 (defun info-lookup-interactive-arguments (topic &optional query)
 289   "Read and return argument value (and help mode) for help topic TOPIC.
 290 If optional argument QUERY is non-nil, query for the help mode."
 291   (let* ((mode (cond (query
 292                       (info-lookup-change-mode topic))
 293                      ((info-lookup->mode-value topic (info-lookup-select-mode))
 294                       info-lookup-mode)
 295                      ((info-lookup-change-mode topic))))
 296          (completions (info-lookup->completions topic mode))
 297          (default (info-lookup-guess-default topic mode))
 298          (completion-ignore-case (info-lookup->ignore-case topic mode))
 299          (enable-recursive-minibuffers t)
 300          (value (completing-read
 301                  (if default
 302                      (format "Describe %s (default %s): " topic default)
 303                    (format "Describe %s: " topic))
 304                  completions nil nil nil 'info-lookup-history default)))
 305     (list (if (equal value "") default value) mode)))
 306
 307 (defun info-lookup-select-mode ()
 308   (when (and (not info-lookup-mode) (buffer-file-name))
 309     (let ((file-name (file-name-nondirectory (buffer-file-name)))
 310           (file-name-alist info-lookup-file-name-alist))
 311       (while (and (not info-lookup-mode) file-name-alist)
 312         (when (string-match (caar file-name-alist) file-name)
 313           (setq info-lookup-mode (cdar file-name-alist)))
 314         (setq file-name-alist (cdr file-name-alist)))))
 315
 316   ;; If major-mode has no setups in info-lookup-alist, under any topic, then
 317   ;; search up through derived-mode-parent to find a parent mode which does
 318   ;; have some setups.  This means that a `define-derived-mode' with no
 319   ;; setups of its own will select its parent mode for lookups, if one of
 320   ;; its parents has some setups.  Good for example on `makefile-gmake-mode'
 321   ;; and similar derivatives of `makefile-mode'.
 322   ;;
 323   (let ((mode major-mode)) ;; Look for `mode' with some setups.
 324     (while (and mode (not info-lookup-mode))
 325       (dolist (topic-cell info-lookup-alist) ;; Usually only two topics here.
 326         (if (info-lookup->mode-value (car topic-cell) mode)
 327             (setq info-lookup-mode mode)))
 328       (setq mode (get mode 'derived-mode-parent))))
 329
 330   (or info-lookup-mode (setq info-lookup-mode major-mode)))
 331
 332 (defun info-lookup-change-mode (topic)
 333   (let* ((completions (mapcar (lambda (arg)
 334                                 (cons (symbol-name (car arg)) (car arg)))
 335                               (info-lookup->topic-value topic)))
 336          (mode (completing-read
 337                 (format "Use %s help mode: " topic)
 338                 completions nil t nil 'info-lookup-history)))
 339     (or (setq mode (cdr (assoc mode completions)))
 340         (error "No %s help available" topic))
 341     (or (info-lookup->mode-value topic mode)
 342         (error "No %s help available for `%s'" topic mode))
 343     (setq info-lookup-mode mode)))
 344
 345 (defun info-lookup (topic item mode)
 346   "Display the documentation of a help item."
 347   (or mode (setq mode (info-lookup-select-mode)))
 348   (or (info-lookup->mode-value topic mode)
 349       (error "No %s help available for `%s'" topic mode))
 350   (let* ((completions (info-lookup->completions topic mode))
 351          (ignore-case (info-lookup->ignore-case topic mode))
 352          (entry (or (assoc (if ignore-case (downcase item) item) completions)
 353                     (assoc-string item completions t)
 354                     (error "Not documented as a %s: %s" topic (or item ""))))
 355          (modes (info-lookup->all-modes topic mode))
 356          (window (selected-window))
 357          (new-Info-history
 358           ;; Avoid clobbering Info-history with nodes searched during
 359           ;; lookup.  If lookup succeeds set `Info-history' to
 360           ;; `new-Info-history'.
 361           (when (get-buffer "*info*")
 362             (with-current-buffer "*info*"
 363               (cons (list Info-current-file Info-current-node (point))
 364                     Info-history))))
 365          found doc-spec node prefix suffix doc-found)
 366     (unless (eq major-mode 'Info-mode)
 367       (if (not info-lookup-other-window-flag)
 368           (info)
 369         (save-window-excursion (info))
 370         (let* ((info-window (get-buffer-window "*info*" t))
 371                (info-frame (and info-window (window-frame info-window))))
 372           (if (and info-frame
 373                    (not (eq info-frame (selected-frame)))
 374                    (display-multi-frame-p)
 375                    (memq info-frame (frames-on-display-list)))
 376               ;; *info* is visible in another frame on same display.
 377               ;; Raise that frame and select the window.
 378               (progn
 379                 (select-window info-window)
 380                 (raise-frame info-frame))
 381             ;; In any other case, switch to *info* in another window.
 382             (switch-to-buffer-other-window "*info*")))))
 383     (while (and (not found) modes)
 384       (setq doc-spec (info-lookup->doc-spec topic (car modes)))
 385       (while (and (not found) doc-spec)
 386         (setq node (nth 0 (car doc-spec))
 387               prefix (nth 2 (car doc-spec))
 388               suffix (nth 3 (car doc-spec)))
 389         (when (condition-case nil
 390                   (progn
 391                     ;; Don't need Index menu fontifications here, and
 392                     ;; they slow down the lookup.
 393                     (let (Info-fontify-maximum-menu-size
 394                           Info-history-list)
 395                       (Info-goto-node node)
 396                       (setq doc-found t)))
 397                 (error
 398                  (message "Cannot access Info node %s" node)
 399                  (sit-for 1)
 400                  nil))
 401           (condition-case nil
 402               (progn
 403                 ;; Don't use Info-menu, it forces case-fold-search to t
 404                 (let ((case-fold-search nil))
 405                   (re-search-forward
 406                    (concat "^\\* " (regexp-quote (or (cdr entry) (car entry)))
 407                            ":")))
 408                 (Info-follow-nearest-node)
 409                 (setq found t)
 410                 (if (or prefix suffix)
 411                     (let ((case-fold-search
 412                            (info-lookup->ignore-case topic (car modes)))
 413                           (buffer-read-only nil))
 414                       (goto-char (point-min))
 415                       (re-search-forward
 416                        (concat prefix (regexp-quote (car entry)) suffix))
 417                       (goto-char (match-beginning 0))
 418                       (and (display-color-p) info-lookup-highlight-face
 419                            ;; Search again for ITEM so that the first
 420                            ;; occurrence of ITEM will be highlighted.
 421                            (re-search-forward (regexp-quote (car entry)))
 422                            (let ((start (match-beginning 0))
 423                                  (end (match-end 0)))
 424                              (if (overlayp info-lookup-highlight-overlay)
 425                                  (move-overlay info-lookup-highlight-overlay
 426                                                start end (current-buffer))
 427                                (setq info-lookup-highlight-overlay
 428                                      (make-overlay start end))))
 429                            (overlay-put info-lookup-highlight-overlay
 430                                         'face info-lookup-highlight-face)))))
 431             (error nil)))
 432         (setq doc-spec (cdr doc-spec)))
 433       (setq modes (cdr modes)))
 434     ;; Alert the user if case was munged, and do this after bringing up the
 435     ;; info buffer since that can print messages
 436     (unless (or ignore-case
 437                 (string-equal item (car entry)))
 438       (message "Found in different case: %s" (car entry)))
 439     (when found
 440       (setq Info-history new-Info-history))
 441     (or doc-found
 442         (error "Info documentation for lookup was not found"))
 443     ;; Don't leave the Info buffer if the help item couldn't be looked up.
 444     (if (and info-lookup-other-window-flag found)
 445         (select-window window))))
 446
 447 (defun info-lookup-setup-mode (topic mode)
 448   "Initialize the internal data structure."
 449   (or (info-lookup->initialized topic mode)
 450       (let ((initialized 0)
 451             cell data completions refer-modes Info-history-list)
 452         (if (not (info-lookup->mode-value topic mode))
 453             (message "No %s help available for `%s'" topic mode)
 454           ;; Recursively setup cross references.
 455           ;; But refer only to non-void modes.
 456           (dolist (arg (info-lookup->other-modes topic mode))
 457             (or (info-lookup->initialized topic arg)
 458                 (info-lookup-setup-mode topic arg))
 459             (and (eq (info-lookup->initialized topic arg) t)
 460                  (setq refer-modes (cons arg refer-modes))))
 461           (setq refer-modes (nreverse refer-modes))
 462           ;; Build the full completion alist.
 463           (setq completions
 464                 (nconc (condition-case nil
 465                            (info-lookup-make-completions topic mode)
 466                          (error nil))
 467                        (apply 'append
 468                               (mapcar (lambda (arg)
 469                                         (info-lookup->completions topic arg))
 470                                       refer-modes))))
 471           (setq initialized t))
 472         ;; Update `info-lookup-cache'.
 473         (setq cell (info-lookup->mode-cache topic mode)
 474               data (list initialized completions refer-modes))
 475         (if (not cell)
 476             (setcdr (info-lookup->cache topic)
 477                     (cons (cons mode data) (info-lookup->topic-cache topic)))
 478           (setcdr cell data))
 479         initialized)))
 480
 481 (defun info-lookup-make-completions (topic mode)
 482   "Create a unique alist from all index entries."
 483   (let ((doc-spec (info-lookup->doc-spec topic mode))
 484         (regexp (concat "^\\(" (info-lookup->regexp topic mode)
 485                         "\\)\\([ \t].*\\)?$"))
 486         Info-history-list Info-fontify-maximum-menu-size
 487         node trans entry item prefix result doc-found
 488         (buffer (get-buffer-create " temp-info-look")))
 489     (with-current-buffer buffer
 490       (Info-mode))
 491     (while doc-spec
 492       (setq node (nth 0 (car doc-spec))
 493             trans (cond ((eq (nth 1 (car doc-spec)) nil)
 494                          (lambda (arg)
 495                            (if (string-match regexp arg)
 496                                (match-string 1 arg))))
 497                         ((stringp (nth 1 (car doc-spec)))
 498                          (setq prefix (nth 1 (car doc-spec)))
 499                          (lambda (arg)
 500                            (if (string-match "^\\([^: \t\n]+\\)" arg)
 501                                (concat prefix (match-string 1 arg)))))
 502                         (t (nth 1 (car doc-spec)))))
 503       (with-current-buffer buffer
 504         (message "Processing Info node `%s'..." node)
 505         (when (condition-case nil
 506                   (progn
 507                     (Info-goto-node node)
 508                     (setq doc-found t))
 509                 (error
 510                  (message "Cannot access Info node `%s'" node)
 511                  (sit-for 1)
 512                  nil))
 513           (condition-case nil
 514               (progn
 515                 (goto-char (point-min))
 516                 (and (search-forward "\n* Menu:" nil t)
 517                      (while (re-search-forward "\n\\* \\(.*\\): " nil t)
 518                        (setq entry (match-string 1)
 519                              item (funcall trans entry))
 520                        ;; `trans' can return nil if the regexp doesn't match.
 521                        (when (and item
 522                                   ;; Sometimes there's more than one Menu:
 523                                   (not (string= entry "Menu")))
 524                          (and (info-lookup->ignore-case topic mode)
 525                               (setq item (downcase item)))
 526                          (and (string-equal entry item)
 527                               (setq entry nil))
 528                          (and (or (assoc item result)
 529                                   (setq result (cons (cons item entry)
 530                                                      result))))))))
 531             (error nil))))
 532       (message "Processing Info node `%s'...done" node)
 533       (setq doc-spec (cdr doc-spec)))
 534     (or doc-found
 535         (error "Info documentation for lookup was not found"))
 536     result))
 537
 538 (defun info-lookup-guess-default (topic mode)
 539   "Return a guess for a symbol to look up, based on text around point.
 540 Try all related modes applicable to TOPIC and MODE.
 541 Return nil if there is nothing appropriate in the buffer near point."
 542   (let ((modes (info-lookup->all-modes topic mode))
 543         guess)
 544     (while (and (not guess) modes)
 545       (setq guess (info-lookup-guess-default* topic (car modes))
 546             modes (cdr modes)))
 547     ;; Collapse whitespace characters.
 548     (when guess
 549       (let ((pos 0))
 550         (while (string-match "[ \t\n]+" guess pos)
 551           (setq pos (1+ (match-beginning 0)))
 552           (setq guess (replace-match " " t t guess)))))
 553     guess))
 554
 555 (defun info-lookup-guess-default* (topic mode)
 556   (let ((case-fold-search (info-lookup->ignore-case topic mode))
 557         (rule (or (info-lookup->parse-rule topic mode)
 558                   (info-lookup->regexp topic mode)))
 559         (start (point)) end regexp subexp result)
 560     (save-excursion
 561       (if (symbolp rule)
 562           (setq result (funcall rule))
 563         (if (consp rule)
 564             (setq regexp (car rule)
 565                   subexp (cdr rule))
 566           (setq regexp rule
 567                 subexp 0))
 568         ;; If at start of symbol, don't go back to end of previous one.
 569         (if (save-match-data
 570               (looking-at "[ \t\n]"))
 571             (skip-chars-backward " \t\n"))
 572         (setq end (point))
 573         (while (and (re-search-backward regexp nil t)
 574                     (looking-at regexp)
 575                     (>= (match-end 0) end))
 576           (setq result (match-string subexp)))
 577         (if (not result)
 578             (progn
 579               (goto-char start)
 580               (skip-chars-forward " \t\n")
 581               (and (looking-at regexp)
 582                    (setq result (match-string subexp)))))))
 583     result))
 584
 585 (defun info-lookup-guess-c-symbol ()
 586   "Get the C symbol at point."
 587   (condition-case nil
 588       (progn
 589         (skip-syntax-backward "w_")
 590         (let ((start (point)) prefix name)
 591           ;; Test for a leading `struct', `union', or `enum' keyword
 592           ;; but ignore names like `foo_struct'.
 593           (setq prefix (and (< (skip-chars-backward " \t\n") 0)
 594                             (< (skip-chars-backward "_a-zA-Z0-9") 0)
 595                             (looking-at "\\(struct\\|union\\|enum\\)\\s ")
 596                             (concat (match-string 1) " ")))
 597           (goto-char start)
 598           (and (looking-at "[_a-zA-Z][_a-zA-Z0-9]*")
 599                (setq name (match-string 0)))
 600           ;; Caveat!  Look forward if point is at `struct' etc.
 601           (and (not prefix)
 602                (or (string-equal name "struct")
 603                    (string-equal name "union")
 604                    (string-equal name "enum"))
 605                (looking-at "[a-z]+\\s +\\([_a-zA-Z][_a-zA-Z0-9]*\\)")
 606                (setq prefix (concat name " ")
 607                      name (match-string 1)))
 608           (and (or prefix name)
 609                (concat prefix name))))
 610     (error nil)))
 611
 612 (defun info-lookup-guess-custom-symbol ()
 613   "Get symbol at point in custom buffers."
 614   (condition-case nil
 615       (save-excursion
 616         (let ((case-fold-search t)
 617               (ignored-chars "][()`'‘’,:.\" \t\n")
 618               (significant-chars "^][()`'‘’,:.\" \t\n")
 619               beg end)
 620           (cond
 621            ((and (memq (get-char-property (point) 'face)
 622                          '(custom-variable-tag custom-variable-tag-face))
 623                    (setq beg (previous-single-char-property-change
 624                               (point) 'face nil (line-beginning-position)))
 625                    (setq end (next-single-char-property-change
 626                               (point) 'face nil (line-end-position)))
 627                    (> end beg))
 628             (subst-char-in-string
 629              ?\s ?\- (buffer-substring-no-properties beg end)))
 630            ((or (and (looking-at (concat "[" significant-chars "]"))
 631                      (save-excursion
 632                        (skip-chars-backward significant-chars)
 633                        (setq beg (point)))
 634                      (skip-chars-forward significant-chars)
 635                      (setq end (point))
 636                      (> end beg))
 637                 (and (looking-at "[ \t\n]")
 638                      (looking-back (concat "[" significant-chars "]")
 639                                    (1- (point)))
 640                      (setq end (point))
 641                      (skip-chars-backward significant-chars)
 642                      (setq beg (point))
 643                      (> end beg))
 644                 (and (skip-chars-forward ignored-chars)
 645                      (setq beg (point))
 646                      (skip-chars-forward significant-chars)
 647                      (setq end (point))
 648                      (> end beg)))
 649             (buffer-substring-no-properties beg end)))))
 650     (error nil)))
 651
 652 (defun info-lookup-guess-gdb-script-symbol ()
 653   "Get symbol at point in GDB script buffers."
 654   (condition-case nil
 655       (save-excursion
 656         (back-to-indentation)
 657         ;; Try to find the current line's full command in the index;
 658         ;; and default to the longest subset that is found.
 659         (when (looking-at "[-a-z]+\\(\\s-[-a-z]+\\)*")
 660           (let ((str-list (split-string (match-string-no-properties 0)
 661                                         "\\s-+" t))
 662                 (completions (info-lookup->completions 'symbol
 663                                                        'gdb-script-mode)))
 664             (catch 'result
 665               (while str-list
 666                 (let ((str (string-join str-list " ")))
 667                   (when (assoc str completions)
 668                     (throw 'result str))
 669                   (nbutlast str-list)))))))
 670     (error nil)))
 671
 672 ;;;###autoload
 673 (defun info-complete-symbol (&optional mode)
 674   "Perform completion on symbol preceding point."
 675   (interactive)
 676   (info-complete 'symbol
 677                  (or mode
 678                      (if (info-lookup->mode-value
 679                           'symbol (info-lookup-select-mode))
 680                          info-lookup-mode
 681                        (info-lookup-change-mode 'symbol)))))
 682
 683 ;;;###autoload
 684 (defun info-complete-file (&optional mode)
 685   "Perform completion on file preceding point."
 686   (interactive)
 687   (info-complete 'file
 688                  (or mode
 689                      (if (info-lookup->mode-value
 690                           'file (info-lookup-select-mode))
 691                          info-lookup-mode
 692                        (info-lookup-change-mode 'file)))))
 693
 694 (defun info-lookup-completions-at-point (topic mode)
 695   "Try to complete a help item."
 696   (or mode (setq mode (info-lookup-select-mode)))
 697   (when (info-lookup->mode-value topic mode)
 698     (let ((modes (info-lookup-quick-all-modes topic mode))
 699           (start (point))
 700           try)
 701       (while (and (not try) modes)
 702         (setq mode (car modes)
 703               modes (cdr modes)
 704               try (info-lookup-guess-default* topic mode))
 705         (goto-char start))
 706       (when try
 707         (let ((completions (info-lookup->completions topic mode)))
 708           (when completions
 709             (when (info-lookup->ignore-case topic mode)
 710               (setq completions
 711                     (lambda (string pred action)
 712                       (let ((completion-ignore-case t))
 713                         (complete-with-action
 714                          action completions string pred)))))
 715             (save-excursion
 716               ;; Find the original symbol and zap it.
 717               (end-of-line)
 718               (while (and (search-backward try nil t)
 719                           (< start (point))))
 720               (list (match-beginning 0) (match-end 0) completions
 721                     :exclusive 'no))))))))
 722
 723 (defun info-complete (topic mode)
 724   "Try to complete a help item."
 725   (barf-if-buffer-read-only)
 726   (let ((data (info-lookup-completions-at-point topic mode)))
 727     (if (null data)
 728         (error "No %s completion available for `%s' at point" topic mode)
 729       (completion-in-region (nth 0 data) (nth 1 data) (nth 2 data)))))
 730
 731 \f
 732 ;;; Initialize some common modes.
 733
 734 (info-lookup-maybe-add-help
 735  :mode 'c-mode :topic 'symbol
 736  :regexp "\\(struct \\|union \\|enum \\)?[_a-zA-Z][_a-zA-Z0-9]*"
 737  :doc-spec '(("(libc)Function Index" nil
 738               "^[ \t]+-+ \\(Function\\|Macro\\): .*\\<" "\\>")
 739              ;; prefix/suffix has to match things like
 740              ;;   " -- Macro: int F_DUPFD"
 741              ;;   " -- Variable: char * tzname [2]"
 742              ;;   "`DBL_MAX'"    (texinfo @table)
 743              ;; suffix "\\>" is not used because that sends DBL_MAX to
 744              ;; DBL_MAX_EXP ("_" is a non-word char)
 745              ("(libc)Variable Index" nil
 746               "^\\([ \t]+-+ \\(Variable\\|Macro\\): .*\\<\\|['`‘]\\)"
 747               "\\( \\|['’]?$\\)")
 748              ("(libc)Type Index" nil
 749               "^[ \t]+-+ Data Type: \\<" "\\>")
 750              ("(termcap)Var Index" nil
 751               "^[ \t]*['`‘]" "['’]"))
 752  :parse-rule 'info-lookup-guess-c-symbol)
 753
 754 (info-lookup-maybe-add-help
 755  :mode 'c-mode :topic 'file
 756  :regexp "[_a-zA-Z0-9./+-]+"
 757  :doc-spec '(("(libc)File Index")))
 758
 759 (info-lookup-maybe-add-help
 760  :mode 'bison-mode
 761  :regexp "[:;|]\\|%\\([%{}]\\|[_a-z]+\\)\\|YY[_A-Z]+\\|yy[_a-z]+"
 762  :doc-spec '(("(bison)Index" nil
 763               "['`‘]" "['’]"))
 764  :parse-rule "[:;|]\\|%\\([%{}]\\|[_a-zA-Z][_a-zA-Z0-9]*\\)"
 765  :other-modes '(c-mode))
 766
 767 (info-lookup-maybe-add-help
 768  :mode 'makefile-mode
 769  :regexp "\\$[^({]\\|\\.[_A-Z]*\\|[_a-zA-Z][_a-zA-Z0-9-]*"
 770  :doc-spec '(("(make)Name Index" nil
 771               "^[ \t]*['`‘]" "['’]"))
 772  :parse-rule "\\$[^({]\\|\\.[_A-Z]*\\|[_a-zA-Z0-9-]+")
 773
 774 (info-lookup-maybe-add-help
 775  :topic      'symbol
 776  :mode       'makefile-automake-mode
 777  ;; similar regexp/parse-rule as makefile-mode, but also the following
 778  ;; (which have index entries),
 779  ;;   "##" special automake comment
 780  ;;   "+=" append operator, separate from the GNU make one
 781  :regexp     "\\$[^({]\\|\\.[_A-Z]*\\|[_a-zA-Z][_a-zA-Z0-9-]*\\|##\\|\\+="
 782  :parse-rule "\\$[^({]\\|\\.[_A-Z]*\\|[_a-zA-Z0-9-]+\\|##\\|\\+="
 783  :doc-spec   '(
 784                ;; "(automake)Macro Index" is autoconf macros used in
 785                ;; configure.ac, not Makefile.am, so don't have that here.
 786                ("(automake)Variable Index" nil "^[ \t]*['`‘]" "['’]")
 787                ;; In automake 1.4 macros and variables were a combined node.
 788                ("(automake)Macro and Variable Index" nil "^[ \t]*['`‘]"
 789                 "['’]")
 790                ;; Directives like "if" are in the "General Index".
 791                ;; Prefix "`" since the text for say `+=' isn't always an
 792                ;; @item etc and so not always at the start of a line.
 793                ("(automake)General Index" nil "['`‘]" "['’]")
 794                ;; In automake 1.3 there was just a single "Index" node.
 795                ("(automake)Index" nil "['`‘]" "['’]"))
 796  :other-modes '(makefile-mode))
 797
 798 (info-lookup-maybe-add-help
 799  :mode 'texinfo-mode
 800  :regexp "@\\([a-zA-Z]+\\|[^a-zA-Z]\\)"
 801  :doc-spec '(("(texinfo)Command and Variable Index"
 802               ;; Ignore Emacs commands and prepend a `@'.
 803               (lambda (item)
 804                 (if (string-match "^\\([a-zA-Z]+\\|[^a-zA-Z]\\)\\( .*\\)?$" item)
 805                     (concat "@" (match-string 1 item))))
 806               "['`‘]" "['’ ]")))
 807
 808 (info-lookup-maybe-add-help
 809  :mode 'm4-mode
 810  :regexp "[_a-zA-Z][_a-zA-Z0-9]*"
 811  :doc-spec '(("(m4)Macro index"))
 812  :parse-rule "[_a-zA-Z0-9]+")
 813
 814 (info-lookup-maybe-add-help
 815  :mode 'autoconf-mode
 816  :regexp "A[CM]_[_A-Z0-9]+"
 817  :doc-spec '(;; Autoconf Macro Index entries are without an "AC_" prefix,
 818              ;; but with "AH_" or "AU_" for those.  So add "AC_" if there
 819              ;; isn't already an "A._".
 820              ("(autoconf)Autoconf Macro Index"
 821               (lambda (item)
 822                 (if (string-match "^A._" item) item (concat "AC_" item)))
 823               "^[ \t]+-+ \\(Macro\\|Variable\\): .*\\<" "\\>")
 824              ;; M4 Macro Index entries are without "AS_" prefixes, and
 825              ;; mostly without "m4_" prefixes.  "dnl" is an exception, not
 826              ;; wanting any prefix.  So AS_ is added back to upper-case
 827              ;; names (if needed), m4_ to others which don't already an m4_.
 828              ("(autoconf)M4 Macro Index"
 829               (lambda (item)
 830                 (let ((case-fold-search nil))
 831                   (cond ((or (string-equal item "dnl")
 832                              (string-match "^m4_" item)
 833                              ;; Autoconf 2.62 index includes some macros
 834                              ;; (e.g., AS_HELP_STRING), so avoid prefixing.
 835                              (string-match "^AS_" item))
 836                          item)
 837                         ((string-match "^[A-Z0-9_]+$" item)
 838                          (concat "AS_" item))
 839                         (t
 840                          (concat "m4_" item)))))
 841               "^[ \t]+-+ Macro: .*\\<" "\\>")
 842              ;; Autotest Macro Index entries are without "AT_".
 843              ("(autoconf)Autotest Macro Index" "AT_"
 844               "^[ \t]+-+ Macro: .*\\<" "\\>")
 845              ;; This is for older versions (probably pre autoconf 2.5x):
 846              ("(autoconf)Macro Index" "AC_"
 847               "^[ \t]+-+ \\(Macro\\|Variable\\): .*\\<" "\\>")
 848              ;; Automake has index entries for its notes on various autoconf
 849              ;; macros (eg. AC_PROG_CC).  Ensure this is after the autoconf
 850              ;; index, so as to prefer the autoconf docs.
 851              ("(automake)Macro and Variable Index" nil
 852               "^[ \t]*['`‘]" "['’]"))
 853  ;; Autoconf symbols are M4 macros.  Thus use M4's parser.
 854  :parse-rule 'ignore
 855  :other-modes '(m4-mode))
 856
 857 (info-lookup-maybe-add-help
 858  :mode 'awk-mode
 859  :regexp "[_a-zA-Z]+"
 860  :doc-spec '(("(gawk)Index"
 861               (lambda (item)
 862                 (let ((case-fold-search nil))
 863                   (cond
 864                    ;; `BEGIN' and `END'.
 865                    ((string-match "^\\([A-Z]+\\) special pattern\\b" item)
 866                     (match-string 1 item))
 867                    ;; `if', `while', `do', ...
 868                    ((string-match "^\\([a-z]+\\) statement\\b" item)
 869                     (if (not (string-equal (match-string 1 item) "control"))
 870                         (match-string 1 item)))
 871                    ;; `NR', `NF', ...
 872                    ((string-match "^[A-Z]+$" item)
 873                     item)
 874                    ;; Built-in functions (matches to many entries).
 875                    ((string-match "^[a-z]+$" item)
 876                     item))))
 877               "['`‘]" "\\([ \t]*([^)]*)\\)?['’]")))
 878
 879 (info-lookup-maybe-add-help
 880  :mode 'perl-mode
 881  :regexp "[$@%][^a-zA-Z]\\|\\$\\^[A-Z]\\|[$@%]?[a-zA-Z][_a-zA-Z0-9]*"
 882  :doc-spec '(("(perl5)Function Index"
 883               (lambda (item)
 884                 (if (string-match "^\\([a-zA-Z0-9]+\\)" item)
 885                     (match-string 1 item)))
 886               "^" "\\b")
 887              ("(perl5)Variable Index"
 888               (lambda (item)
 889                 ;; Work around bad formatted array variables.
 890                 (let ((sym (cond ((or (string-match "^\\$\\(.\\|@@\\)$" item)
 891                                       (string-match "^\\$\\^[A-Z]$" item))
 892                                   item)
 893                                  ((string-match
 894                                    "^\\([$%@]\\|@@\\)?[_a-zA-Z0-9]+" item)
 895                                   (match-string 0 item))
 896                                  (t ""))))
 897                   (if (string-match "@@" sym)
 898                       (setq sym (concat (substring sym 0 (match-beginning 0))
 899                                         (substring sym (1- (match-end 0))))))
 900                   (if (string-equal sym "") nil sym)))
 901               "^" "\\b"))
 902  :parse-rule "[$@%]?\\([_a-zA-Z0-9]+\\|[^a-zA-Z]\\)")
 903
 904 (info-lookup-maybe-add-help
 905  :mode 'cperl-mode
 906  :regexp "[$@%][^a-zA-Z]\\|\\$\\^[A-Z]\\|[$@%]?[a-zA-Z][_a-zA-Z0-9]*"
 907  :other-modes '(perl-mode))
 908
 909 (info-lookup-maybe-add-help
 910  :mode 'latex-mode
 911  :regexp "\\\\\\([a-zA-Z]+\\|[^a-zA-Z]\\)"
 912  :doc-spec `((,(if (Info-find-file "latex2e" t)
 913                    ;; From http://home.gna.org/latexrefman
 914                    "(latex2e)Command Index"
 915                  "(latex)Command Index")
 916               ;; \frac{NUM}{DEN} etc can have more than one {xx} argument.
 917               ;; \sqrt[ROOT]{num} and others can have square brackets.
 918               nil "[`'‘]" "\\({[^}]*}|\\[[^]]*\\]\\)*['’]")))
 919
 920
 921 (info-lookup-maybe-add-help
 922  :mode 'emacs-lisp-mode
 923  :regexp "[^][()`'‘’,\" \t\n]+"
 924  :doc-spec '(;; Commands with key sequences appear in nodes as `foo' and
 925              ;; those without as `M-x foo'.
 926              ("(emacs)Command Index"  nil "['`‘]\\(M-x[ \t\n]+\\)?" "['’]")
 927              ;; Variables normally appear in nodes as just `foo'.
 928              ("(emacs)Variable Index" nil "['`‘]" "['’]")
 929              ;; Almost all functions, variables, etc appear in nodes as
 930              ;; " -- Function: foo" etc.  A small number of aliases and
 931              ;; symbols appear only as `foo', and will miss out on exact
 932              ;; positions.  Allowing `foo' would hit too many false matches
 933              ;; for things that should go to Function: etc, and those latter
 934              ;; are much more important.  Perhaps this could change if some
 935              ;; sort of fallback match scheme existed.
 936              ("(elisp)Index"          nil "^ -+ .*: " "\\( \\|$\\)")
 937              ("(cl)Function Index"    nil "^ -+ .*: " "\\( \\|$\\)")
 938              ("(cl)Variable Index"    nil "^ -+ .*: " "\\( \\|$\\)")))
 939
 940 ;; docstrings talk about elisp, so have apropos-mode follow emacs-lisp-mode
 941 (info-lookup-maybe-add-help
 942  :mode 'apropos-mode
 943  :regexp "[^][()`'‘’,\" \t\n]+" ;; same as emacs-lisp-mode above
 944  :other-modes '(emacs-lisp-mode))
 945
 946 (info-lookup-maybe-add-help
 947  :mode 'lisp-interaction-mode
 948  :regexp "[^][()`'‘’,\" \t\n]+"
 949  :parse-rule 'ignore
 950  :other-modes '(emacs-lisp-mode))
 951
 952 (info-lookup-maybe-add-help
 953  :mode 'lisp-mode
 954  :regexp "[^()`'‘’,\" \t\n]+"
 955  :parse-rule 'ignore
 956  :other-modes '(emacs-lisp-mode))
 957
 958 (info-lookup-maybe-add-help
 959  :mode 'scheme-mode
 960  :regexp "[^()`'‘’,\" \t\n]+"
 961  :ignore-case t
 962  ;; Aubrey Jaffer's rendition from <https://people.csail.mit.edu/jaffer/SCM>
 963  :doc-spec '(("(r5rs)Index" nil
 964               "^[ \t]+-+ [^:]+:[ \t]*" "\\b")))
 965
 966 (info-lookup-maybe-add-help
 967  :mode 'octave-mode
 968  :regexp "[_a-zA-Z0-9]+\\|\\s.+\\|[-!=^|*/.\\,><~&+]\\{1,3\\}\\|[][();,\"']"
 969  :doc-spec '(("(octave)Function Index" nil
 970               "^ -+ [^:]+:[ ]+\\(\\[[^=]*=[ ]+\\)?" nil)
 971              ("(octave)Variable Index" nil "^ -+ [^:]+:[ ]+" nil)
 972              ("(octave)Operator Index" nil nil nil)
 973              ;; Catch lines of the form "xyz statement"
 974              ("(octave)Concept Index"
 975               (lambda (item)
 976                 (cond
 977                  ((string-match "^\\([A-Z]+\\) statement\\b" item)
 978                     (match-string 1 item))
 979                  (t nil)))
 980               nil; "^ -+ [^:]+:[ ]+" don't think this prefix is useful here.
 981               nil)))
 982
 983 (info-lookup-maybe-add-help
 984  :mode 'maxima-mode
 985  :ignore-case t
 986  :regexp "[a-zA-Z0-9_%]+"
 987  :doc-spec '( ("(maxima)Function and Variable Index" nil
 988                "^ -+ [^:]+:[ ]+\\(\\[[^=]*=[ ]+\\)?" nil)))
 989
 990 (info-lookup-maybe-add-help
 991  :mode 'inferior-maxima-mode
 992  :regexp "[a-zA-Z0-9_%]+"
 993  :other-modes '(maxima-mode))
 994
 995 ;; coreutils and bash builtins overlap in places, eg. printf, so there's a
 996 ;; question which should come first.  Some of the coreutils descriptions are
 997 ;; more detailed, but if bash is usually /bin/sh on a GNU system then the
 998 ;; builtins will be what's normally run.
 999 ;;
1000 ;; Maybe special variables like $? should be matched as $?, not just ?.
1001 ;; This would avoid a clash between variable $! and negation !, or variable
1002 ;; $# and comment # (though comment # is not currently indexed in bash).
1003 ;; Unfortunately if $? etc is the symbol, then we wouldn't be taken to the
1004 ;; exact spot in the relevant node, since the bash manual has just `?' etc
1005 ;; there.  Maybe an extension to the prefix/suffix scheme could help this.
1006
1007 (info-lookup-maybe-add-help
1008  :mode 'sh-mode :topic 'symbol
1009  ;; bash has "." and ":" in its index, but those chars will probably never
1010  ;; work in info, so don't bother matching them in the regexp.
1011  :regexp "\\([a-zA-Z0-9_-]+\\|[!{}@*#?$]\\|\\[\\[?\\|]]?\\)"
1012  :doc-spec '(("(bash)Builtin Index"       nil "^['`‘]" "[ .'’]")
1013              ("(bash)Reserved Word Index" nil "^['`‘]" "[ .'’]")
1014              ("(bash)Variable Index"      nil "^['`‘]" "[ .'’]")
1015
1016              ;; coreutils (version 4.5.10) doesn't have a separate program
1017              ;; index, so exclude extraneous stuff (most of it) by demanding
1018              ;; "[a-z]+" in the trans-func.
1019              ;; coreutils version 8.1 has node "Concept Index" and past
1020              ;; versions have node "Index", look for both, whichever is
1021              ;; absent is quietly ignored
1022              ("(coreutils)Index"
1023               (lambda (item) (if (string-match "\\`[a-z]+\\'" item) item)))
1024              ("(coreutils)Concept Index"
1025               (lambda (item) (if (string-match "\\`[a-z]+\\'" item) item)))
1026
1027              ;; diff (version 2.8.1) has only a few programs, index entries
1028              ;; are things like "foo invocation".
1029              ("(diff)Index"
1030               (lambda (item)
1031                 (if (string-match "\\`\\([a-z]+\\) invocation\\'" item)
1032                     (match-string 1 item))))
1033              ;; there's no plain "sed" index entry as such, mung another
1034              ;; hopefully unique one to get to the invocation section
1035              ("(sed)Concept Index"
1036               (lambda (item)
1037                 (if (string-equal item "Standard input, processing as input")
1038                     "sed")))
1039              ;; there's no plain "awk" or "gawk" index entries, mung other
1040              ;; hopefully unique ones to get to the command line options
1041              ("(gawk)Index"
1042               (lambda (item)
1043                 (cond ((string-equal item "gawk, extensions, disabling")
1044                        "awk")
1045                       ((string-equal item "gawk, versions of, information about, printing")
1046                        "gawk"))))))
1047
1048 ;; This misses some things which occur as node names but not in the
1049 ;; index.  Unfortunately it also picks up the wrong one of multiple
1050 ;; entries for the same term in some cases.  --fx
1051 (info-lookup-maybe-add-help
1052  :mode 'cfengine-mode
1053  :regexp "[[:alnum:]_]+\\(?:()\\)?"
1054  :doc-spec '(("(cfengine-Reference)Variable Index"
1055               (lambda (item)
1056                 ;; Index entries may be like `IsPlain()'
1057                 (if (string-match "\\([[:alnum:]_]+\\)()" item)
1058                     (match-string 1 item)
1059                   item))
1060               ;; This gets functions in evaluated classes.  Other
1061               ;; possible patterns don't seem to work too well.
1062               "['`‘]" "(")))
1063
1064 (info-lookup-maybe-add-help
1065  :mode 'Custom-mode
1066  :ignore-case t
1067  :regexp "[^][()`'‘’,:\" \t\n]+"
1068  :parse-rule 'info-lookup-guess-custom-symbol
1069  :other-modes '(emacs-lisp-mode))
1070
1071 (info-lookup-maybe-add-help
1072  :mode 'help-mode
1073  :regexp "[^][()`'‘’,:\" \t\n]+"
1074  :other-modes '(emacs-lisp-mode))
1075
1076 (info-lookup-maybe-add-help
1077  :mode 'gdb-script-mode
1078  :ignore-case nil
1079  :regexp "\\([-a-z]+\\(\\s-+[-a-z]+\\)*\\)"
1080  :doc-spec '(("(gdb)Command and Variable Index" nil
1081               nil nil))
1082  :parse-rule 'info-lookup-guess-gdb-script-symbol)
1083 \f
1084 (provide 'info-look)
1085
1086 ;;; info-look.el ends here