lisp/info-look.el

   1 ;;; info-look.el --- major-mode-sensitive Info index lookup facility
   2 ;; An older version of this was known as libc.el.
   3
   4 ;; Copyright (C) 1995, 1996, 1997, 1998, 1999, 2001, 2002, 2003,
   5 ;;   2004, 2005, 2006 Free Software Foundation, Inc.
   6
   7 ;; Author: Ralph Schleicher <rs@nunatak.allgaeu.org>
   8 ;;         (did not show signs of life (Nov 2001)  -stef)
   9 ;; Keywords: help languages
  10
  11 ;; This file is part of GNU Emacs.
  12
  13 ;; GNU Emacs is free software; you can redistribute it and/or modify
  14 ;; it under the terms of the GNU General Public License as published by
  15 ;; the Free Software Foundation; either version 2, or (at your option)
  16 ;; any later version.
  17
  18 ;; GNU Emacs is distributed in the hope that it will be useful,
  19 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  20 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21 ;; GNU General Public License for more details.
  22
  23 ;; You should have received a copy of the GNU General Public License
  24 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  25 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  26 ;; Boston, MA 02110-1301, USA.
  27
  28 ;;; Commentary:
  29
  30 ;; Really cool code to lookup info indexes.
  31 ;; Try especially info-lookup-symbol (aka C-h S).
  32
  33 ;;; Code:
  34
  35 (require 'info)
  36
  37 (defgroup info-lookup nil
  38   "Major mode sensitive help agent."
  39   :group 'help :group 'languages)
  40
  41 (defvar info-lookup-mode nil
  42   "Symbol of the current buffer's help mode.
  43 Help is provided according to the buffer's major mode if value is nil.
  44 Automatically becomes buffer local when set in any fashion.")
  45 (make-variable-buffer-local 'info-lookup-mode)
  46
  47 (defcustom info-lookup-other-window-flag t
  48   "Non-nil means pop up the Info buffer in another window."
  49   :group 'info-lookup :type 'boolean)
  50
  51 (defcustom info-lookup-highlight-face 'match
  52   "Face for highlighting looked up help items.
  53 Setting this variable to nil disables highlighting."
  54   :group 'info-lookup :type 'face)
  55
  56 (defvar info-lookup-highlight-overlay nil
  57   "Overlay object used for highlighting.")
  58
  59 (defcustom info-lookup-file-name-alist
  60   '(("\\`ac\\(local\\|site\\|include\\)\\.m4\\'" . autoconf-mode))
  61   "Alist of file names handled specially.
  62 List elements are cons cells of the form
  63
  64     (REGEXP . MODE)
  65
  66 If a file name matches REGEXP, then use help mode MODE instead of the
  67 buffer's major mode."
  68   :group 'info-lookup :type '(repeat (cons (string :tag "Regexp")
  69                                            (symbol :tag "Mode"))))
  70
  71 (defvar info-lookup-history nil
  72   "History of previous input lines.")
  73
  74 (defvar info-lookup-alist nil
  75   "Alist of known help topics.
  76 Cons cells are of the form
  77
  78     (HELP-TOPIC . HELP-DATA)
  79
  80 HELP-TOPIC is the symbol of a help topic.
  81 HELP-DATA is a HELP-TOPIC's public data set.
  82  Value is an alist with elements of the form
  83
  84     (HELP-MODE REGEXP IGNORE-CASE DOC-SPEC PARSE-RULE OTHER-MODES)
  85
  86 HELP-MODE is a mode's symbol.
  87 REGEXP is a regular expression matching those help items whose
  88  documentation can be looked up via DOC-SPEC.
  89 IGNORE-CASE is non-nil if help items are case insensitive.
  90 DOC-SPEC is a list of documentation specifications of the form
  91
  92     (INFO-NODE TRANS-FUNC PREFIX SUFFIX)
  93
  94 INFO-NODE is the name (including file name part) of an Info index.
  95 TRANS-FUNC is a function translating index entries into help items;
  96  nil means add only those index entries matching REGEXP, a string
  97  means prepend string to the first word of all index entries.
  98 PREFIX and SUFFIX are parts of a regular expression.  If one of
  99  them is non-nil then search the help item's Info node for the
 100  first occurrence of the regular expression `PREFIX ITEM SUFFIX'.
 101  ITEM will be highlighted with `info-lookup-highlight-face' if this
 102  variable is not nil.
 103 PARSE-RULE is either the symbol name of a function or a regular
 104  expression for guessing the default help item at point.  Fuzzy
 105  regular expressions like \"[_a-zA-Z0-9]+\" do a better job if
 106  there are no clear delimiters; do not try to write too complex
 107  expressions.  PARSE-RULE defaults to REGEXP.
 108 OTHER-MODES is a list of cross references to other help modes.")
 109
 110 (defsubst info-lookup->topic-value (topic)
 111   (cdr (assoc topic info-lookup-alist)))
 112
 113 (defsubst info-lookup->mode-value (topic mode)
 114   (assoc mode (info-lookup->topic-value topic)))
 115
 116 (defsubst info-lookup->regexp (topic mode)
 117   (nth 1 (info-lookup->mode-value topic mode)))
 118
 119 (defsubst info-lookup->ignore-case (topic mode)
 120   (nth 2 (info-lookup->mode-value topic mode)))
 121
 122 (defsubst info-lookup->doc-spec (topic mode)
 123   (nth 3 (info-lookup->mode-value topic mode)))
 124
 125 (defsubst info-lookup->parse-rule (topic mode)
 126   (nth 4 (info-lookup->mode-value topic mode)))
 127
 128 (defsubst info-lookup->other-modes (topic mode)
 129   (nth 5 (info-lookup->mode-value topic mode)))
 130
 131 (defun info-lookup-add-help (&rest arg)
 132   "Add or update a help specification.
 133 Function arguments are one or more options of the form
 134
 135     KEYWORD ARGUMENT
 136
 137 KEYWORD is either `:topic', `:mode', `:regexp', `:ignore-case',
 138  `:doc-spec', `:parse-rule', or `:other-modes'.
 139 ARGUMENT has a value as explained in the documentation of the
 140  variable `info-lookup-alist'.
 141
 142 If no topic or mode option has been specified, then the help topic defaults
 143 to `symbol', and the help mode defaults to the current major mode."
 144   (apply 'info-lookup-add-help* nil arg))
 145
 146 (defun info-lookup-maybe-add-help (&rest arg)
 147   "Add a help specification iff none is defined.
 148 See the documentation of the function `info-lookup-add-help'
 149 for more details."
 150   (apply 'info-lookup-add-help* t arg))
 151
 152 (defun info-lookup-add-help* (maybe &rest arg)
 153   (let (topic mode regexp ignore-case doc-spec
 154               parse-rule other-modes keyword value)
 155     (setq topic 'symbol
 156           mode major-mode
 157           regexp "\\w+")
 158     (while arg
 159       (setq keyword (car arg))
 160       (or (symbolp keyword)
 161           (error "Junk in argument list \"%S\"" arg))
 162       (setq arg (cdr arg))
 163       (and (null arg)
 164            (error "Keyword \"%S\" is missing an argument" keyword))
 165       (setq value (car arg)
 166             arg (cdr arg))
 167       (cond ((eq keyword :topic)
 168              (setq topic value))
 169             ((eq keyword :mode)
 170              (setq mode value))
 171             ((eq keyword :regexp)
 172              (setq regexp value))
 173             ((eq keyword :ignore-case)
 174              (setq ignore-case value))
 175             ((eq keyword :doc-spec)
 176              (setq doc-spec value))
 177             ((eq keyword :parse-rule)
 178              (setq parse-rule value))
 179             ((eq keyword :other-modes)
 180              (setq other-modes value))
 181             (t
 182              (error "Unknown keyword \"%S\"" keyword))))
 183     (or (and maybe (info-lookup->mode-value topic mode))
 184         (let* ((data (list regexp ignore-case doc-spec parse-rule other-modes))
 185                (topic-cell (or (assoc topic info-lookup-alist)
 186                                (car (setq info-lookup-alist
 187                                           (cons (cons topic nil)
 188                                                 info-lookup-alist)))))
 189                (mode-cell (assoc mode topic-cell)))
 190           (if (null mode-cell)
 191               (setcdr topic-cell (cons (cons mode data) (cdr topic-cell)))
 192             (setcdr mode-cell data))))
 193     nil))
 194
 195 (defvar info-lookup-cache nil
 196   "Cache storing data maintained automatically by the program.
 197 Value is an alist with cons cell of the form
 198
 199     (HELP-TOPIC . ((HELP-MODE INITIALIZED COMPLETIONS REFER-MODES) ...))
 200
 201 HELP-TOPIC is the symbol of a help topic.
 202 HELP-MODE is a mode's symbol.
 203 INITIALIZED is nil if HELP-MODE is uninitialized, t if
 204  HELP-MODE is initialized, and `0' means HELP-MODE is
 205  initialized but void.
 206 COMPLETIONS is an alist of documented help items.
 207 REFER-MODES is a list of other help modes to use.")
 208
 209 (defsubst info-lookup->cache (topic)
 210   (or (assoc topic info-lookup-cache)
 211       (car (setq info-lookup-cache
 212                  (cons (cons topic nil)
 213                        info-lookup-cache)))))
 214
 215 (defun info-lookup->topic-cache (topic)
 216   (cdr (info-lookup->cache topic)))
 217
 218 (defun info-lookup->mode-cache (topic mode)
 219   (assoc mode (info-lookup->topic-cache topic)))
 220
 221 (defun info-lookup->initialized (topic mode)
 222   (nth 1 (info-lookup->mode-cache topic mode)))
 223
 224 (defun info-lookup->completions (topic mode)
 225   (or (info-lookup->initialized topic mode)
 226       (info-lookup-setup-mode topic mode))
 227   (nth 2 (info-lookup->mode-cache topic mode)))
 228
 229 (defun info-lookup->refer-modes (topic mode)
 230   (or (info-lookup->initialized topic mode)
 231       (info-lookup-setup-mode topic mode))
 232   (nth 3 (info-lookup->mode-cache topic mode)))
 233
 234 (defun info-lookup->all-modes (topic mode)
 235   (cons mode (info-lookup->refer-modes topic mode)))
 236
 237 (defun info-lookup-quick-all-modes (topic mode)
 238   (cons mode (info-lookup->other-modes topic mode)))
 239
 240 ;;;###autoload
 241 (defun info-lookup-reset ()
 242   "Throw away all cached data.
 243 This command is useful if the user wants to start at the beginning without
 244 quitting Emacs, for example, after some Info documents were updated on the
 245 system."
 246   (interactive)
 247   (setq info-lookup-cache nil))
 248
 249 ;;;###autoload (put 'info-lookup-symbol 'info-file "emacs")
 250 ;;;###autoload
 251 (defun info-lookup-symbol (symbol &optional mode)
 252   "Display the definition of SYMBOL, as found in the relevant manual.
 253 When this command is called interactively, it reads SYMBOL from the minibuffer.
 254 In the minibuffer, use M-n to yank the default argument value
 255 into the minibuffer so you can edit it.
 256 The default symbol is the one found at point.
 257
 258 With prefix arg a query for the symbol help mode is offered."
 259   (interactive
 260    (info-lookup-interactive-arguments 'symbol current-prefix-arg))
 261   (info-lookup 'symbol symbol mode))
 262
 263 ;;;###autoload (put 'info-lookup-file 'info-file "emacs")
 264 ;;;###autoload
 265 (defun info-lookup-file (file &optional mode)
 266   "Display the documentation of a file.
 267 When this command is called interactively, it reads FILE from the minibuffer.
 268 In the minibuffer, use M-n to yank the default file name
 269 into the minibuffer so you can edit it.
 270 The default file name is the one found at point.
 271
 272 With prefix arg a query for the file help mode is offered."
 273   (interactive
 274    (info-lookup-interactive-arguments 'file current-prefix-arg))
 275   (info-lookup 'file file mode))
 276
 277 (defun info-lookup-interactive-arguments (topic &optional query)
 278   "Read and return argument value (and help mode) for help topic TOPIC.
 279 If optional argument QUERY is non-nil, query for the help mode."
 280   (let* ((mode (cond (query
 281                       (info-lookup-change-mode topic))
 282                      ((info-lookup->mode-value topic (info-lookup-select-mode))
 283                       info-lookup-mode)
 284                      ((info-lookup-change-mode topic))))
 285          (completions (info-lookup->completions topic mode))
 286          (default (info-lookup-guess-default topic mode))
 287          (completion-ignore-case (info-lookup->ignore-case topic mode))
 288          (enable-recursive-minibuffers t)
 289          (value (completing-read
 290                  (if default
 291                      (format "Describe %s (default %s): " topic default)
 292                    (format "Describe %s: " topic))
 293                  completions nil nil nil 'info-lookup-history default)))
 294     (list (if (equal value "") default value) mode)))
 295
 296 (defun info-lookup-select-mode ()
 297   (when (and (not info-lookup-mode) (buffer-file-name))
 298     (let ((file-name (file-name-nondirectory (buffer-file-name)))
 299           (file-name-alist info-lookup-file-name-alist))
 300       (while (and (not info-lookup-mode) file-name-alist)
 301         (when (string-match (caar file-name-alist) file-name)
 302           (setq info-lookup-mode (cdar file-name-alist)))
 303         (setq file-name-alist (cdr file-name-alist)))))
 304   (or info-lookup-mode (setq info-lookup-mode major-mode)))
 305
 306 (defun info-lookup-change-mode (topic)
 307   (let* ((completions (mapcar (lambda (arg)
 308                                 (cons (symbol-name (car arg)) (car arg)))
 309                               (info-lookup->topic-value topic)))
 310          (mode (completing-read
 311                 (format "Use %s help mode: " topic)
 312                 completions nil t nil 'info-lookup-history)))
 313     (or (setq mode (cdr (assoc mode completions)))
 314         (error "No %s help available" topic))
 315     (or (info-lookup->mode-value topic mode)
 316         (error "No %s help available for `%s'" topic mode))
 317     (setq info-lookup-mode mode)))
 318
 319 (defun info-lookup (topic item mode)
 320   "Display the documentation of a help item."
 321   (or mode (setq mode (info-lookup-select-mode)))
 322   (or (info-lookup->mode-value topic mode)
 323       (error "No %s help available for `%s'" topic mode))
 324   (let* ((completions (info-lookup->completions topic mode))
 325          (ignore-case (info-lookup->ignore-case topic mode))
 326          (entry (or (assoc (if ignore-case (downcase item) item) completions)
 327                     (assoc-string item completions t)
 328                     (error "Not documented as a %s: %s" topic (or item ""))))
 329          (modes (info-lookup->all-modes topic mode))
 330          (window (selected-window))
 331          found doc-spec node prefix suffix doc-found)
 332     (if (not (eq major-mode 'Info-mode))
 333         (if (not info-lookup-other-window-flag)
 334             (info)
 335           (progn
 336             (save-window-excursion (info))
 337             ;; Determine whether or not the Info buffer is visible in
 338             ;; another frame on the same display.  If it is, simply raise
 339             ;; that frame.  Otherwise, display it in another window.
 340             (let* ((window (get-buffer-window "*info*" t))
 341                    (info-frame (and window (window-frame window))))
 342               (if (and info-frame
 343                        (display-multi-frame-p)
 344                        (memq info-frame (frames-on-display-list))
 345                        (not (eq info-frame (selected-frame))))
 346                   (select-frame info-frame)
 347                 (switch-to-buffer-other-window "*info*"))))))
 348     (while (and (not found) modes)
 349       (setq doc-spec (info-lookup->doc-spec topic (car modes)))
 350       (while (and (not found) doc-spec)
 351         (setq node (nth 0 (car doc-spec))
 352               prefix (nth 2 (car doc-spec))
 353               suffix (nth 3 (car doc-spec)))
 354         (when (condition-case error-data
 355                   (progn
 356                     (Info-goto-node node)
 357                     (setq doc-found t))
 358                 (error
 359                  (message "Cannot access Info node %s" node)
 360                  (sit-for 1)
 361                  nil))
 362           (condition-case nil
 363               (progn
 364                 ;; Don't use Info-menu, it forces case-fold-search to t
 365                 (let ((case-fold-search nil))
 366                   (re-search-forward
 367                    (concat "^\\* " (regexp-quote (or (cdr entry) (car entry)))
 368                            ":")))
 369                 (Info-follow-nearest-node)
 370                 (setq found t)
 371                 (if (or prefix suffix)
 372                     (let ((case-fold-search
 373                            (info-lookup->ignore-case topic (car modes)))
 374                           (buffer-read-only nil))
 375                       (goto-char (point-min))
 376                       (re-search-forward
 377                        (concat prefix (regexp-quote (car entry)) suffix))
 378                       (goto-char (match-beginning 0))
 379                       (and (display-color-p) info-lookup-highlight-face
 380                            ;; Search again for ITEM so that the first
 381                            ;; occurrence of ITEM will be highlighted.
 382                            (re-search-forward (regexp-quote (car entry)))
 383                            (let ((start (match-beginning 0))
 384                                  (end (match-end 0)))
 385                              (if (overlayp info-lookup-highlight-overlay)
 386                                  (move-overlay info-lookup-highlight-overlay
 387                                                start end (current-buffer))
 388                                (setq info-lookup-highlight-overlay
 389                                      (make-overlay start end))))
 390                            (overlay-put info-lookup-highlight-overlay
 391                                         'face info-lookup-highlight-face)))))
 392             (error nil)))
 393         (setq doc-spec (cdr doc-spec)))
 394       (setq modes (cdr modes)))
 395     ;; Alert the user if case was munged, and do this after bringing up the
 396     ;; info buffer since that can print messages
 397     (unless (or ignore-case
 398                 (string-equal item (car entry)))
 399       (message "Found in different case: %s" (car entry)))
 400     (or doc-found
 401         (error "Info documentation for lookup was not found"))
 402     ;; Don't leave the Info buffer if the help item couldn't be looked up.
 403     (if (and info-lookup-other-window-flag found)
 404         (select-window window))))
 405
 406 (defun info-lookup-setup-mode (topic mode)
 407   "Initialize the internal data structure."
 408   (or (info-lookup->initialized topic mode)
 409       (let (cell data (initialized 0) completions refer-modes)
 410         (if (not (info-lookup->mode-value topic mode))
 411             (message "No %s help available for `%s'" topic mode)
 412           ;; Recursively setup cross references.
 413           ;; But refer only to non-void modes.
 414           (dolist (arg (info-lookup->other-modes topic mode))
 415             (or (info-lookup->initialized topic arg)
 416                 (info-lookup-setup-mode topic arg))
 417             (and (eq (info-lookup->initialized topic arg) t)
 418                  (setq refer-modes (cons arg refer-modes))))
 419           (setq refer-modes (nreverse refer-modes))
 420           ;; Build the full completion alist.
 421           (setq completions
 422                 (nconc (condition-case nil
 423                            (info-lookup-make-completions topic mode)
 424                          (error nil))
 425                        (apply 'append
 426                               (mapcar (lambda (arg)
 427                                         (info-lookup->completions topic arg))
 428                                       refer-modes))))
 429           (setq initialized t))
 430         ;; Update `info-lookup-cache'.
 431         (setq cell (info-lookup->mode-cache topic mode)
 432               data (list initialized completions refer-modes))
 433         (if (not cell)
 434             (setcdr (info-lookup->cache topic)
 435                     (cons (cons mode data) (info-lookup->topic-cache topic)))
 436           (setcdr cell data))
 437         initialized)))
 438
 439 (defun info-lookup-make-completions (topic mode)
 440   "Create a unique alist from all index entries."
 441   (let ((doc-spec (info-lookup->doc-spec topic mode))
 442         (regexp (concat "^\\(" (info-lookup->regexp topic mode)
 443                         "\\)\\([ \t].*\\)?$"))
 444         node trans entry item prefix result doc-found
 445         (buffer (get-buffer-create " temp-info-look")))
 446     (with-current-buffer buffer
 447       (Info-mode))
 448     (while doc-spec
 449       (setq node (nth 0 (car doc-spec))
 450             trans (cond ((eq (nth 1 (car doc-spec)) nil)
 451                          (lambda (arg)
 452                            (if (string-match regexp arg)
 453                                (match-string 1 arg))))
 454                         ((stringp (nth 1 (car doc-spec)))
 455                          (setq prefix (nth 1 (car doc-spec)))
 456                          (lambda (arg)
 457                            (if (string-match "^\\([^: \t\n]+\\)" arg)
 458                                (concat prefix (match-string 1 arg)))))
 459                         (t (nth 1 (car doc-spec)))))
 460       (with-current-buffer buffer
 461         (message "Processing Info node `%s'..." node)
 462         (when (condition-case error-data
 463                   (progn
 464                     (Info-goto-node node)
 465                     (setq doc-found t))
 466                 (error
 467                  (message "Cannot access Info node `%s'" node)
 468                  (sit-for 1)
 469                  nil))
 470           (condition-case nil
 471               (progn
 472                 (goto-char (point-min))
 473                 (and (search-forward "\n* Menu:" nil t)
 474                      (while (re-search-forward "\n\\* \\(.*\\): " nil t)
 475                        (setq entry (match-string 1)
 476                              item (funcall trans entry))
 477                        ;; `trans' can return nil if the regexp doesn't match.
 478                        (when (and item
 479                                   ;; Sometimes there's more than one Menu:
 480                                   (not (string= entry "Menu")))
 481                          (and (info-lookup->ignore-case topic mode)
 482                               (setq item (downcase item)))
 483                          (and (string-equal entry item)
 484                               (setq entry nil))
 485                          (and (or (assoc item result)
 486                                   (setq result (cons (cons item entry)
 487                                                      result))))))))
 488             (error nil))))
 489       (message "Processing Info node `%s'...done" node)
 490       (setq doc-spec (cdr doc-spec)))
 491     (or doc-found
 492         (error "Info documentation for lookup was not found"))
 493     result))
 494
 495 (defun info-lookup-guess-default (topic mode)
 496   "Return a guess for a symbol to look up, based on text around point.
 497 Try all related modes applicable to TOPIC and MODE.
 498 Return nil if there is nothing appropriate in the buffer near point."
 499   (let ((modes (info-lookup->all-modes topic mode))
 500         guess)
 501     (while (and (not guess) modes)
 502       (setq guess (info-lookup-guess-default* topic (car modes))
 503             modes (cdr modes)))
 504     ;; Collapse whitespace characters.
 505     (when guess
 506       (let ((pos 0))
 507         (while (string-match "[ \t\n]+" guess pos)
 508           (setq pos (1+ (match-beginning 0)))
 509           (setq guess (replace-match " " t t guess)))))
 510     guess))
 511
 512 (defun info-lookup-guess-default* (topic mode)
 513   (let ((case-fold-search (info-lookup->ignore-case topic mode))
 514         (rule (or (info-lookup->parse-rule topic mode)
 515                   (info-lookup->regexp topic mode)))
 516         (start (point)) end regexp subexp result)
 517     (save-excursion
 518       (if (symbolp rule)
 519           (setq result (funcall rule))
 520         (if (consp rule)
 521             (setq regexp (car rule)
 522                   subexp (cdr rule))
 523           (setq regexp rule
 524                 subexp 0))
 525         ;; If at start of symbol, don't go back to end of previous one.
 526         (if (save-match-data
 527               (looking-at "[ \t\n]"))
 528             (skip-chars-backward " \t\n"))
 529         (setq end (point))
 530         (while (and (re-search-backward regexp nil t)
 531                     (looking-at regexp)
 532                     (>= (match-end 0) end))
 533           (setq result (match-string subexp)))
 534         (if (not result)
 535             (progn
 536               (goto-char start)
 537               (skip-chars-forward " \t\n")
 538               (and (looking-at regexp)
 539                    (setq result (match-string subexp)))))))
 540     result))
 541
 542 (defun info-lookup-guess-c-symbol ()
 543   "Get the C symbol at point."
 544   (condition-case nil
 545       (progn
 546         (skip-syntax-backward "w_")
 547         (let ((start (point)) prefix name)
 548           ;; Test for a leading `struct', `union', or `enum' keyword
 549           ;; but ignore names like `foo_struct'.
 550           (setq prefix (and (< (skip-chars-backward " \t\n") 0)
 551                             (< (skip-chars-backward "_a-zA-Z0-9") 0)
 552                             (looking-at "\\(struct\\|union\\|enum\\)\\s ")
 553                             (concat (match-string 1) " ")))
 554           (goto-char start)
 555           (and (looking-at "[_a-zA-Z][_a-zA-Z0-9]*")
 556                (setq name (match-string 0)))
 557           ;; Caveat!  Look forward if point is at `struct' etc.
 558           (and (not prefix)
 559                (or (string-equal name "struct")
 560                    (string-equal name "union")
 561                    (string-equal name "enum"))
 562                (looking-at "[a-z]+\\s +\\([_a-zA-Z][_a-zA-Z0-9]*\\)")
 563                (setq prefix (concat name " ")
 564                      name (match-string 1)))
 565           (and (or prefix name)
 566                (concat prefix name))))
 567     (error nil)))
 568
 569 ;;;###autoload
 570 (defun info-complete-symbol (&optional mode)
 571   "Perform completion on symbol preceding point."
 572   (interactive)
 573   (info-complete 'symbol
 574                  (or mode
 575                      (if (info-lookup->mode-value
 576                           'symbol (info-lookup-select-mode))
 577                          info-lookup-mode
 578                        (info-lookup-change-mode 'symbol)))))
 579
 580 ;;;###autoload
 581 (defun info-complete-file (&optional mode)
 582   "Perform completion on file preceding point."
 583   (interactive)
 584   (info-complete 'file
 585                  (or mode
 586                      (if (info-lookup->mode-value
 587                           'file (info-lookup-select-mode))
 588                          info-lookup-mode
 589                        (info-lookup-change-mode 'file)))))
 590
 591 (defun info-complete (topic mode)
 592   "Try to complete a help item."
 593   (barf-if-buffer-read-only)
 594   (or mode (setq mode (info-lookup-select-mode)))
 595   (or (info-lookup->mode-value topic mode)
 596       (error "No %s completion available for `%s'" topic mode))
 597   (let ((modes (info-lookup-quick-all-modes topic mode))
 598         (start (point))
 599         try)
 600     (while (and (not try) modes)
 601       (setq mode (car modes)
 602             modes (cdr modes)
 603             try (info-lookup-guess-default* topic mode))
 604       (goto-char start))
 605     (and (not try)
 606          (error "Found no %S to complete" topic))
 607     (let ((completions (info-lookup->completions topic mode))
 608           (completion-ignore-case (info-lookup->ignore-case topic mode))
 609           completion)
 610       (setq completion (try-completion try completions))
 611       (cond ((not completion)
 612              (ding)
 613              (message "No match"))
 614             ((stringp completion)
 615              (or (assoc completion completions)
 616                  (setq completion (completing-read
 617                                    (format "Complete %S: " topic)
 618                                    completions nil t completion
 619                                    info-lookup-history)))
 620              ;; Find the original symbol and zap it.
 621              (end-of-line)
 622              (while (and (search-backward try nil t)
 623                          (< start (point))))
 624              (replace-match "")
 625              (insert completion))
 626             (t
 627              (message "%s is complete"
 628                       (capitalize (prin1-to-string topic))))))))
 629
 630 \f
 631 ;;; Initialize some common modes.
 632
 633 (info-lookup-maybe-add-help
 634  :mode 'c-mode :topic 'symbol
 635  :regexp "\\(struct \\|union \\|enum \\)?[_a-zA-Z][_a-zA-Z0-9]*"
 636  :doc-spec '(("(libc)Function Index" nil
 637               "^[ \t]+-+ \\(Function\\|Macro\\): .*\\<" "\\>")
 638              ;; prefix/suffix has to match things like
 639              ;;   " -- Macro: int F_DUPFD"
 640              ;;   " -- Variable: char * tzname [2]"
 641              ;;   "`DBL_MAX'"    (texinfo @table)
 642              ;; suffix "\\>" is not used because that sends DBL_MAX to
 643              ;; DBL_MAX_EXP ("_" is a non-word char)
 644              ("(libc)Variable Index" nil
 645               "^\\([ \t]+-+ \\(Variable\\|Macro\\): .*\\<\\|`\\)"
 646               "\\( \\|'?$\\)")
 647              ("(libc)Type Index" nil
 648               "^[ \t]+-+ Data Type: \\<" "\\>")
 649              ("(termcap)Var Index" nil
 650               "^[ \t]*`" "'"))
 651  :parse-rule 'info-lookup-guess-c-symbol)
 652
 653 (info-lookup-maybe-add-help
 654  :mode 'c-mode :topic 'file
 655  :regexp "[_a-zA-Z0-9./+-]+"
 656  :doc-spec '(("(libc)File Index")))
 657
 658 (info-lookup-maybe-add-help
 659  :mode 'bison-mode
 660  :regexp "[:;|]\\|%\\([%{}]\\|[_a-z]+\\)\\|YY[_A-Z]+\\|yy[_a-z]+"
 661  :doc-spec '(("(bison)Index" nil
 662               "`" "'"))
 663  :parse-rule "[:;|]\\|%\\([%{}]\\|[_a-zA-Z][_a-zA-Z0-9]*\\)"
 664  :other-modes '(c-mode))
 665
 666 (info-lookup-maybe-add-help
 667  :mode 'makefile-mode
 668  :regexp "\\$[^({]\\|\\.[_A-Z]*\\|[_a-zA-Z][_a-zA-Z0-9-]*"
 669  :doc-spec '(("(make)Name Index" nil
 670               "^[ \t]*`" "'")
 671              ("(automake)Macro and Variable Index" nil
 672               "^[ \t]*`" "'"))
 673  :parse-rule "\\$[^({]\\|\\.[_A-Z]*\\|[_a-zA-Z0-9-]+"
 674  :other-modes '(automake-mode))
 675
 676 (info-lookup-maybe-add-help
 677  :mode 'texinfo-mode
 678  :regexp "@\\([a-zA-Z]+\\|[^a-zA-Z]\\)"
 679  :doc-spec '(("(texinfo)Command and Variable Index"
 680               ;; Ignore Emacs commands and prepend a `@'.
 681               (lambda (item)
 682                 (if (string-match "^\\([a-zA-Z]+\\|[^a-zA-Z]\\)\\( .*\\)?$" item)
 683                     (concat "@" (match-string 1 item))))
 684               "`" "[' ]")))
 685
 686 (info-lookup-maybe-add-help
 687  :mode 'm4-mode
 688  :regexp "[_a-zA-Z][_a-zA-Z0-9]*"
 689  :doc-spec '(("(m4)Macro index"))
 690  :parse-rule "[_a-zA-Z0-9]+")
 691
 692 (info-lookup-maybe-add-help
 693  :mode 'autoconf-mode
 694  :regexp "A[CM]_[_A-Z0-9]+"
 695  :doc-spec '(;; Autoconf Macro Index entries are without an "AC_" prefix,
 696              ;; but with "AH_" or "AU_" for those.  So add "AC_" if there
 697              ;; isn't already an "A._".
 698              ("(autoconf)Autoconf Macro Index"
 699               (lambda (item)
 700                 (if (string-match "^A._" item) item (concat "AC_" item)))
 701               "^[ \t]+-+ \\(Macro\\|Variable\\): .*\\<" "\\>")
 702              ;; M4 Macro Index entries are without "AS_" prefixes, and
 703              ;; mostly without "m4_" prefixes.  "dnl" is an exception, not
 704              ;; wanting any prefix.  So AS_ is added back to upper-case
 705              ;; names, m4_ to others which don't already an m4_.
 706              ("(autoconf)M4 Macro Index"
 707               (lambda (item)
 708                 (let ((case-fold-search nil))
 709                   (cond ((or (string-equal item "dnl")
 710                              (string-match "^m4_" item))
 711                          item)
 712                         ((string-match "^[A-Z0-9_]+$" item)
 713                          (concat "AS_" item))
 714                         (t
 715                          (concat "m4_" item)))))
 716               "^[ \t]+-+ Macro: .*\\<" "\\>")
 717              ;; Autotest Macro Index entries are without "AT_".
 718              ("(autoconf)Autotest Macro Index" "AT_"
 719               "^[ \t]+-+ Macro: .*\\<" "\\>")
 720              ;; This is for older versions (probably pre autoconf 2.5x):
 721              ("(autoconf)Macro Index" "AC_"
 722               "^[ \t]+-+ \\(Macro\\|Variable\\): .*\\<" "\\>")
 723              ;; Automake has index entries for its notes on various autoconf
 724              ;; macros (eg. AC_PROG_CC).  Ensure this is after the autoconf
 725              ;; index, so as to prefer the autoconf docs.
 726              ("(automake)Macro and Variable Index" nil
 727               "^[ \t]*`" "'"))
 728  ;; Autoconf symbols are M4 macros.  Thus use M4's parser.
 729  :parse-rule 'ignore
 730  :other-modes '(m4-mode))
 731
 732 (info-lookup-maybe-add-help
 733  :mode 'awk-mode
 734  :regexp "[_a-zA-Z]+"
 735  :doc-spec '(("(gawk)Index"
 736               (lambda (item)
 737                 (let ((case-fold-search nil))
 738                   (cond
 739                    ;; `BEGIN' and `END'.
 740                    ((string-match "^\\([A-Z]+\\) special pattern\\b" item)
 741                     (match-string 1 item))
 742                    ;; `if', `while', `do', ...
 743                    ((string-match "^\\([a-z]+\\) statement\\b" item)
 744                     (if (not (string-equal (match-string 1 item) "control"))
 745                         (match-string 1 item)))
 746                    ;; `NR', `NF', ...
 747                    ((string-match "^[A-Z]+$" item)
 748                     item)
 749                    ;; Built-in functions (matches to many entries).
 750                    ((string-match "^[a-z]+$" item)
 751                     item))))
 752               "`" "\\([ \t]*([^)]*)\\)?'")))
 753
 754 (info-lookup-maybe-add-help
 755  :mode 'perl-mode
 756  :regexp "[$@%][^a-zA-Z]\\|\\$\\^[A-Z]\\|[$@%]?[a-zA-Z][_a-zA-Z0-9]*"
 757  :doc-spec '(("(perl5)Function Index"
 758               (lambda (item)
 759                 (if (string-match "^\\([a-zA-Z0-9]+\\)" item)
 760                     (match-string 1 item)))
 761               "^" "\\b")
 762              ("(perl5)Variable Index"
 763               (lambda (item)
 764                 ;; Work around bad formatted array variables.
 765                 (let ((sym (cond ((or (string-match "^\\$\\(.\\|@@\\)$" item)
 766                                       (string-match "^\\$\\^[A-Z]$" item))
 767                                   item)
 768                                  ((string-match
 769                                    "^\\([$%@]\\|@@\\)?[_a-zA-Z0-9]+" item)
 770                                   (match-string 0 item))
 771                                  (t ""))))
 772                   (if (string-match "@@" sym)
 773                       (setq sym (concat (substring sym 0 (match-beginning 0))
 774                                         (substring sym (1- (match-end 0))))))
 775                   (if (string-equal sym "") nil sym)))
 776               "^" "\\b"))
 777  :parse-rule "[$@%]?\\([_a-zA-Z0-9]+\\|[^a-zA-Z]\\)")
 778
 779 (info-lookup-maybe-add-help
 780  :mode 'cperl-mode
 781  :regexp "[$@%][^a-zA-Z]\\|\\$\\^[A-Z]\\|[$@%]?[a-zA-Z][_a-zA-Z0-9]*"
 782  :other-modes '(perl-mode))
 783
 784 (info-lookup-maybe-add-help
 785  :mode 'latex-mode
 786  :regexp "\\\\\\([a-zA-Z]+\\|[^a-zA-Z]\\)"
 787  :doc-spec '(("(latex)Command Index" nil
 788               "`" "\\({[^}]*}\\)?'")))
 789
 790 (info-lookup-maybe-add-help
 791  :mode 'emacs-lisp-mode
 792  :regexp "[^][()'\" \t\n]+"
 793  :doc-spec '(;; Commands with key sequences appear in nodes as `foo' and
 794              ;; those without as `M-x foo'.
 795              ("(emacs)Command Index"  nil "`\\(M-x[ \t\n]+\\)?" "'")
 796              ;; Variables normally appear in nodes as just `foo'.
 797              ("(emacs)Variable Index" nil "`" "'")
 798              ;; Almost all functions, variables, etc appear in nodes as
 799              ;; " -- Function: foo" etc.  A small number of aliases and
 800              ;; symbols appear only as `foo', and will miss out on exact
 801              ;; positions.  Allowing `foo' would hit too many false matches
 802              ;; for things that should go to Function: etc, and those latter
 803              ;; are much more important.  Perhaps this could change if some
 804              ;; sort of fallback match scheme existed.
 805              ("(elisp)Index"          nil "^ -+ .*: " "\\( \\|$\\)")))
 806
 807 (info-lookup-maybe-add-help
 808  :mode 'lisp-interaction-mode
 809  :regexp "[^][()'\" \t\n]+"
 810  :parse-rule 'ignore
 811  :other-modes '(emacs-lisp-mode))
 812
 813 (info-lookup-maybe-add-help
 814  :mode 'lisp-mode
 815  :regexp "[^()'\" \t\n]+"
 816  :parse-rule 'ignore
 817  :other-modes '(emacs-lisp-mode))
 818
 819 (info-lookup-maybe-add-help
 820  :mode 'scheme-mode
 821  :regexp "[^()`',\" \t\n]+"
 822  :ignore-case t
 823  ;; Aubrey Jaffer's rendition from <URL:ftp://ftp-swiss.ai.mit.edu/pub/scm>
 824  :doc-spec '(("(r5rs)Index" nil
 825               "^[ \t]+-+ [^:]+:[ \t]*" "\\b")))
 826
 827 (info-lookup-maybe-add-help
 828  :mode 'octave-mode
 829  :regexp "[_a-zA-Z0-9]+"
 830  :doc-spec '(("(octave)Function Index" nil
 831               "^ -+ [^:]+:[ ]+\\(\\[[^=]*=[ ]+\\)?" nil)
 832              ("(octave)Variable Index" nil "^ -+ [^:]+:[ ]+" nil)
 833              ;; Catch lines of the form "xyz statement"
 834              ("(octave)Concept Index"
 835               (lambda (item)
 836                 (cond
 837                  ((string-match "^\\([A-Z]+\\) statement\\b" item)
 838                     (match-string 1 item))
 839                  (t nil)))
 840               nil; "^ -+ [^:]+:[ ]+" don't think this prefix is useful here.
 841               nil)))
 842
 843 (info-lookup-maybe-add-help
 844  :mode 'maxima-mode
 845  :ignore-case t
 846  :regexp "[a-zA-Z_%]+"
 847  :doc-spec '( ("(maxima)Function and Variable Index" nil
 848                "^ -+ [^:]+:[ ]+\\(\\[[^=]*=[ ]+\\)?" nil)))
 849
 850 (info-lookup-maybe-add-help
 851  :mode 'inferior-maxima-mode
 852  :other-modes '(maxima-mode))
 853
 854 ;; coreutils and bash builtins overlap in places, eg. printf, so there's a
 855 ;; question which should come first.  Some of the coreutils descriptions are
 856 ;; more detailed, but if bash is usually /bin/sh on a GNU system then the
 857 ;; builtins will be what's normally run.
 858 ;;
 859 ;; Maybe special variables like $? should be matched as $?, not just ?.
 860 ;; This would avoid a clash between variable $! and negation !, or variable
 861 ;; $# and comment # (though comment # is not currently indexed in bash).
 862 ;; Unfortunately if $? etc is the symbol, then we wouldn't be taken to the
 863 ;; exact spot in the relevant node, since the bash manual has just `?' etc
 864 ;; there.  Maybe an extension to the prefix/suffix scheme could help this.
 865
 866 (info-lookup-maybe-add-help
 867  :mode 'sh-mode :topic 'symbol
 868  ;; bash has "." and ":" in its index, but those chars will probably never
 869  ;; work in info, so don't bother matching them in the regexp.
 870  :regexp "\\([a-zA-Z0-9_-]+\\|[!{}@*#?$]\\|\\[\\[?\\|]]?\\)"
 871  :doc-spec '(("(bash)Builtin Index"       nil "^`" "[ .']")
 872              ("(bash)Reserved Word Index" nil "^`" "[ .']")
 873              ("(bash)Variable Index"      nil "^`" "[ .']")
 874              ;; coreutils (version 4.5.10) doesn't have a separate program
 875              ;; index, so exclude extraneous stuff (most of it) by demanding
 876              ;; "[a-z]+" in the trans-func.
 877              ("(coreutils)Index"
 878               (lambda (item) (if (string-match "\\`[a-z]+\\'" item) item)))
 879              ;; diff (version 2.8.1) has only a few programs, index entries
 880              ;; are things like "foo invocation".
 881              ("(diff)Index"
 882               (lambda (item)
 883                 (if (string-match "\\`\\([a-z]+\\) invocation\\'" item)
 884                     (match-string 1 item))))
 885              ;; there's no plain "sed" index entry as such, mung another
 886              ;; hopefully unique one to get to the invocation section
 887              ("(sed)Concept Index"
 888               (lambda (item)
 889                 (if (string-equal item "Standard input, processing as input")
 890                     "sed")))
 891              ;; there's no plain "awk" or "gawk" index entries, mung other
 892              ;; hopefully unique ones to get to the command line options
 893              ("(gawk)Index"
 894               (lambda (item)
 895                 (cond ((string-equal item "gawk, extensions, disabling")
 896                        "awk")
 897                       ((string-equal item "gawk, versions of, information about, printing")
 898                        "gawk"))))))
 899
 900 ;; This misses some things which occur as node names but not in the
 901 ;; index.  Unfortunately it also picks up the wrong one of multiple
 902 ;; entries for the same term in some cases.  --fx
 903 (info-lookup-maybe-add-help
 904  :mode 'cfengine-mode
 905  :regexp "[[:alnum:]_]+\\(?:()\\)?"
 906  :doc-spec '(("(cfengine-Reference)Variable Index"
 907               (lambda (item)
 908                 ;; Index entries may be like `IsPlain()'
 909                 (if (string-match "\\([[:alnum:]_]+\\)()" item)
 910                     (match-string 1 item)
 911                   item))
 912               ;; This gets functions in evaluated classes.  Other
 913               ;; possible patterns don't seem to work too well.
 914               "`" "(")))
 915 \f
 916 (provide 'info-look)
 917
 918 ;;; arch-tag: 0f1e3ea3-32a2-4461-bbab-3cff93539a74
 919 ;;; info-look.el ends here