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, 2001-2014 Free Software Foundation, Inc.
   5
   6 ;; Author: Ralph Schleicher <rs@nunatak.allgaeu.org>
   7 ;;         (did not show signs of life (Nov 2001)  -stef)
   8 ;; Keywords: help languages
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; GNU Emacs is free software: you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation, either version 3 of the License, or
  15 ;; (at your option) any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  24
  25 ;;; Commentary:
  26
  27 ;; Really cool code to lookup info indexes.
  28 ;; Try especially info-lookup-symbol (aka C-h S).
  29
  30 ;; Some additional sources of (Tex)info files for non-GNU packages:
  31 ;;
  32 ;; Scheme: <URL:http://groups.csail.mit.edu/mac/ftpdir/scm/r5rs.info.tar.gz>
  33 ;; LaTeX:
  34 ;;  <URL:ftp://ctan.tug.org/tex-archive/info/latex2e-help-texinfo/latex2e.texi>
  35 ;;  (or CTAN mirrors)
  36 ;; Perl: <URL:ftp://ftp.cpan.org/pub/CPAN/doc/manual/texinfo/> (or CPAN mirrors)
  37
  38 ;;; Code:
  39
  40 (require 'info)
  41
  42 (defgroup info-lookup nil
  43   "Major mode sensitive help agent."
  44   :group 'help :group 'languages)
  45
  46 (defvar info-lookup-mode nil
  47   "Symbol of the current buffer's help mode.
  48 Help is provided according to the buffer's major mode if value is nil.
  49 Automatically becomes buffer local when set in any fashion.")
  50 (make-variable-buffer-local 'info-lookup-mode)
  51
  52 (defcustom info-lookup-other-window-flag t
  53   "Non-nil means pop up the Info buffer in another window."
  54   :group 'info-lookup :type 'boolean)
  55
  56 (defcustom info-lookup-highlight-face 'match
  57   "Face for highlighting looked up help items.
  58 Setting this variable to nil disables highlighting."
  59   :group 'info-lookup :type 'face)
  60
  61 (defvar info-lookup-highlight-overlay nil
  62   "Overlay object used for highlighting.")
  63
  64 (defcustom info-lookup-file-name-alist
  65   '(("\\`ac\\(local\\|site\\|include\\)\\.m4\\'" . autoconf-mode))
  66   "Alist of file names handled specially.
  67 List elements are cons cells of the form
  68
  69     (REGEXP . MODE)
  70
  71 If a file name matches REGEXP, then use help mode MODE instead of the
  72 buffer's major mode."
  73   :group 'info-lookup :type '(repeat (cons (string :tag "Regexp")
  74                                            (symbol :tag "Mode"))))
  75
  76 (defvar info-lookup-history nil
  77   "History of previous input lines.")
  78
  79 (defvar info-lookup-alist nil
  80   "Alist of known help topics.
  81 Cons cells are of the form
  82
  83     (HELP-TOPIC . HELP-DATA)
  84
  85 HELP-TOPIC is the symbol of a help topic.
  86 HELP-DATA is a HELP-TOPIC's public data set.
  87  Value is an alist with elements of the form
  88
  89     (HELP-MODE REGEXP IGNORE-CASE DOC-SPEC PARSE-RULE OTHER-MODES)
  90
  91 HELP-MODE is a mode's symbol.
  92 REGEXP is a regular expression matching those help items whose
  93  documentation can be looked up via DOC-SPEC.
  94 IGNORE-CASE is non-nil if help items are case insensitive.
  95 DOC-SPEC is a list of documentation specifications of the form
  96
  97     (INFO-NODE TRANS-FUNC PREFIX SUFFIX)
  98
  99 INFO-NODE is the name (including file name part) of an Info index.
 100 TRANS-FUNC is a function translating index entries into help items;
 101  nil means add only those index entries matching REGEXP, a string
 102  means prepend string to the first word of all index entries.
 103 PREFIX and SUFFIX are parts of a regular expression.  If one of
 104  them is non-nil then search the help item's Info node for the
 105  first occurrence of the regular expression `PREFIX ITEM SUFFIX'.
 106  ITEM will be highlighted with `info-lookup-highlight-face' if this
 107  variable is not nil.
 108 PARSE-RULE is either the symbol name of a function or a regular
 109  expression for guessing the default help item at point.  Fuzzy
 110  regular expressions like \"[_a-zA-Z0-9]+\" do a better job if
 111  there are no clear delimiters; do not try to write too complex
 112  expressions.  PARSE-RULE defaults to REGEXP.
 113 OTHER-MODES is a list of cross references to other help modes.")
 114
 115 (defsubst info-lookup->topic-value (topic)
 116   (cdr (assoc topic info-lookup-alist)))
 117
 118 (defsubst info-lookup->mode-value (topic mode)
 119   (assoc mode (info-lookup->topic-value topic)))
 120
 121 (defsubst info-lookup->regexp (topic mode)
 122   (nth 1 (info-lookup->mode-value topic mode)))
 123
 124 (defsubst info-lookup->ignore-case (topic mode)
 125   (nth 2 (info-lookup->mode-value topic mode)))
 126
 127 (defsubst info-lookup->doc-spec (topic mode)
 128   (nth 3 (info-lookup->mode-value topic mode)))
 129
 130 (defsubst info-lookup->parse-rule (topic mode)
 131   (nth 4 (info-lookup->mode-value topic mode)))
 132
 133 (defsubst info-lookup->other-modes (topic mode)
 134   (nth 5 (info-lookup->mode-value topic mode)))
 135
 136 (defun info-lookup-add-help (&rest arg)
 137   "Add or update a help specification.
 138 Function arguments are specified as keyword/argument pairs:
 139
 140     \(KEYWORD . ARGUMENT)
 141
 142 KEYWORD is either `:topic', `:mode', `:regexp', `:ignore-case',
 143  `:doc-spec', `:parse-rule', or `:other-modes'.
 144 ARGUMENT has a value as explained in the documentation of the
 145  variable `info-lookup-alist'.
 146
 147 If no topic or mode option has been specified, then the help topic defaults
 148 to `symbol', and the help mode defaults to the current major mode."
 149   (apply 'info-lookup-add-help* nil arg))
 150
 151 (defun info-lookup-maybe-add-help (&rest arg)
 152   "Add a help specification if none is defined.
 153 See the documentation of the function `info-lookup-add-help'
 154 for more details."
 155   (apply 'info-lookup-add-help* t arg))
 156
 157 (defun info-lookup-add-help* (maybe &rest arg)
 158   (let (topic mode regexp ignore-case doc-spec
 159               parse-rule other-modes keyword value)
 160     (setq topic 'symbol
 161           mode major-mode
 162           regexp "\\w+")
 163     (while arg
 164       (setq keyword (car arg))
 165       (or (symbolp keyword)
 166           (error "Junk in argument list \"%S\"" arg))
 167       (setq arg (cdr arg))
 168       (and (null arg)
 169            (error "Keyword \"%S\" is missing an argument" keyword))
 170       (setq value (car arg)
 171             arg (cdr arg))
 172       (cond ((eq keyword :topic)
 173              (setq topic value))
 174             ((eq keyword :mode)
 175              (setq mode value))
 176             ((eq keyword :regexp)
 177              (setq regexp value))
 178             ((eq keyword :ignore-case)
 179              (setq ignore-case value))
 180             ((eq keyword :doc-spec)
 181              (setq doc-spec value))
 182             ((eq keyword :parse-rule)
 183              (setq parse-rule value))
 184             ((eq keyword :other-modes)
 185              (setq other-modes value))
 186             (t
 187              (error "Unknown keyword \"%S\"" keyword))))
 188     (or (and maybe (info-lookup->mode-value topic mode))
 189         (let* ((data (list regexp ignore-case doc-spec parse-rule other-modes))
 190                (topic-cell (or (assoc topic info-lookup-alist)
 191                                (car (setq info-lookup-alist
 192                                           (cons (cons topic nil)
 193                                                 info-lookup-alist)))))
 194                (mode-cell (assoc mode topic-cell)))
 195           (if (null mode-cell)
 196               (setcdr topic-cell (cons (cons mode data) (cdr topic-cell)))
 197             (setcdr mode-cell data))))
 198     nil))
 199
 200 (defvar info-lookup-cache nil
 201   "Cache storing data maintained automatically by the program.
 202 Value is an alist with cons cell of the form
 203
 204     (HELP-TOPIC . ((HELP-MODE INITIALIZED COMPLETIONS REFER-MODES) ...))
 205
 206 HELP-TOPIC is the symbol of a help topic.
 207 HELP-MODE is a mode's symbol.
 208 INITIALIZED is nil if HELP-MODE is uninitialized, t if
 209  HELP-MODE is initialized, and `0' means HELP-MODE is
 210  initialized but void.
 211 COMPLETIONS is an alist of documented help items.
 212 REFER-MODES is a list of other help modes to use.")
 213
 214 (defsubst info-lookup->cache (topic)
 215   (or (assoc topic info-lookup-cache)
 216       (car (setq info-lookup-cache
 217                  (cons (cons topic nil)
 218                        info-lookup-cache)))))
 219
 220 (defun info-lookup->topic-cache (topic)
 221   (cdr (info-lookup->cache topic)))
 222
 223 (defun info-lookup->mode-cache (topic mode)
 224   (assoc mode (info-lookup->topic-cache topic)))
 225
 226 (defun info-lookup->initialized (topic mode)
 227   (nth 1 (info-lookup->mode-cache topic mode)))
 228
 229 (defun info-lookup->completions (topic mode)
 230   (or (info-lookup->initialized topic mode)
 231       (info-lookup-setup-mode topic mode))
 232   (nth 2 (info-lookup->mode-cache topic mode)))
 233
 234 (defun info-lookup->refer-modes (topic mode)
 235   (or (info-lookup->initialized topic mode)
 236       (info-lookup-setup-mode topic mode))
 237   (nth 3 (info-lookup->mode-cache topic mode)))
 238
 239 (defun info-lookup->all-modes (topic mode)
 240   (cons mode (info-lookup->refer-modes topic mode)))
 241
 242 (defun info-lookup-quick-all-modes (topic mode)
 243   (cons mode (info-lookup->other-modes topic mode)))
 244
 245 ;;;###autoload
 246 (defun info-lookup-reset ()
 247   "Throw away all cached data.
 248 This command is useful if the user wants to start at the beginning without
 249 quitting Emacs, for example, after some Info documents were updated on the
 250 system."
 251   (interactive)
 252   (setq info-lookup-cache nil))
 253
 254 ;;;###autoload (put 'info-lookup-symbol 'info-file "emacs")
 255 ;;;###autoload
 256 (defun info-lookup-symbol (symbol &optional mode)
 257   "Display the definition of SYMBOL, as found in the relevant manual.
 258 When this command is called interactively, it reads SYMBOL from the
 259 minibuffer.  In the minibuffer, use M-n to yank the default argument
 260 value into the minibuffer so you can edit it.  The default symbol is the
 261 one found at point.
 262
 263 With prefix arg MODE a query for the symbol help mode is offered."
 264   (interactive
 265    (info-lookup-interactive-arguments 'symbol current-prefix-arg))
 266   (info-lookup 'symbol symbol mode))
 267
 268 ;;;###autoload (put 'info-lookup-file 'info-file "emacs")
 269 ;;;###autoload
 270 (defun info-lookup-file (file &optional mode)
 271   "Display the documentation of a file.
 272 When this command is called interactively, it reads FILE from the minibuffer.
 273 In the minibuffer, use M-n to yank the default file name
 274 into the minibuffer so you can edit it.
 275 The default file name is the one found at point.
 276
 277 With prefix arg MODE a query for the file help mode is offered."
 278   (interactive
 279    (info-lookup-interactive-arguments 'file current-prefix-arg))
 280   (info-lookup 'file file mode))
 281
 282 (defun info-lookup-interactive-arguments (topic &optional query)
 283   "Read and return argument value (and help mode) for help topic TOPIC.
 284 If optional argument QUERY is non-nil, query for the help mode."
 285   (let* ((mode (cond (query
 286                       (info-lookup-change-mode topic))
 287                      ((info-lookup->mode-value topic (info-lookup-select-mode))
 288                       info-lookup-mode)
 289                      ((info-lookup-change-mode topic))))
 290          (completions (info-lookup->completions topic mode))
 291          (default (info-lookup-guess-default topic mode))
 292          (completion-ignore-case (info-lookup->ignore-case topic mode))
 293          (enable-recursive-minibuffers t)
 294          (value (completing-read
 295                  (if default
 296                      (format "Describe %s (default %s): " topic default)
 297                    (format "Describe %s: " topic))
 298                  completions nil nil nil 'info-lookup-history default)))
 299     (list (if (equal value "") default value) mode)))
 300
 301 (defun info-lookup-select-mode ()
 302   (when (and (not info-lookup-mode) (buffer-file-name))
 303     (let ((file-name (file-name-nondirectory (buffer-file-name)))
 304           (file-name-alist info-lookup-file-name-alist))
 305       (while (and (not info-lookup-mode) file-name-alist)
 306         (when (string-match (caar file-name-alist) file-name)
 307           (setq info-lookup-mode (cdar file-name-alist)))
 308         (setq file-name-alist (cdr file-name-alist)))))
 309
 310   ;; If major-mode has no setups in info-lookup-alist, under any topic, then
 311   ;; search up through derived-mode-parent to find a parent mode which does
 312   ;; have some setups.  This means that a `define-derived-mode' with no
 313   ;; setups of its own will select its parent mode for lookups, if one of
 314   ;; its parents has some setups.  Good for example on `makefile-gmake-mode'
 315   ;; and similar derivatives of `makefile-mode'.
 316   ;;
 317   (let ((mode major-mode)) ;; Look for `mode' with some setups.
 318     (while (and mode (not info-lookup-mode))
 319       (dolist (topic-cell info-lookup-alist) ;; Usually only two topics here.
 320         (if (info-lookup->mode-value (car topic-cell) mode)
 321             (setq info-lookup-mode mode)))
 322       (setq mode (get mode 'derived-mode-parent))))
 323
 324   (or info-lookup-mode (setq info-lookup-mode major-mode)))
 325
 326 (defun info-lookup-change-mode (topic)
 327   (let* ((completions (mapcar (lambda (arg)
 328                                 (cons (symbol-name (car arg)) (car arg)))
 329                               (info-lookup->topic-value topic)))
 330          (mode (completing-read
 331                 (format "Use %s help mode: " topic)
 332                 completions nil t nil 'info-lookup-history)))
 333     (or (setq mode (cdr (assoc mode completions)))
 334         (error "No %s help available" topic))
 335     (or (info-lookup->mode-value topic mode)
 336         (error "No %s help available for `%s'" topic mode))
 337     (setq info-lookup-mode mode)))
 338
 339 (defun info-lookup (topic item mode)
 340   "Display the documentation of a help item."
 341   (or mode (setq mode (info-lookup-select-mode)))
 342   (or (info-lookup->mode-value topic mode)
 343       (error "No %s help available for `%s'" topic mode))
 344   (let* ((completions (info-lookup->completions topic mode))
 345          (ignore-case (info-lookup->ignore-case topic mode))
 346          (entry (or (assoc (if ignore-case (downcase item) item) completions)
 347                     (assoc-string item completions t)
 348                     (error "Not documented as a %s: %s" topic (or item ""))))
 349          (modes (info-lookup->all-modes topic mode))
 350          (window (selected-window))
 351          (new-Info-history
 352           ;; Avoid clobbering Info-history with nodes searched during
 353           ;; lookup.  If lookup succeeds set `Info-history' to
 354           ;; `new-Info-history'.
 355           (when (get-buffer "*info*")
 356             (with-current-buffer "*info*"
 357               (cons (list Info-current-file Info-current-node (point))
 358                     Info-history))))
 359          found doc-spec node prefix suffix doc-found)
 360     (unless (eq major-mode 'Info-mode)
 361       (if (not info-lookup-other-window-flag)
 362           (info)
 363         (save-window-excursion (info))
 364         (let* ((info-window (get-buffer-window "*info*" t))
 365                (info-frame (and info-window (window-frame info-window))))
 366           (if (and info-frame
 367                    (not (eq info-frame (selected-frame)))
 368                    (display-multi-frame-p)
 369                    (memq info-frame (frames-on-display-list)))
 370               ;; *info* is visible in another frame on same display.
 371               ;; Raise that frame and select the window.
 372               (progn
 373                 (select-window info-window)
 374                 (raise-frame info-frame))
 375             ;; In any other case, switch to *info* in another window.
 376             (switch-to-buffer-other-window "*info*")))))
 377     (while (and (not found) modes)
 378       (setq doc-spec (info-lookup->doc-spec topic (car modes)))
 379       (while (and (not found) doc-spec)
 380         (setq node (nth 0 (car doc-spec))
 381               prefix (nth 2 (car doc-spec))
 382               suffix (nth 3 (car doc-spec)))
 383         (when (condition-case nil
 384                   (progn
 385                     ;; Don't need Index menu fontifications here, and
 386                     ;; they slow down the lookup.
 387                     (let (Info-fontify-maximum-menu-size
 388                           Info-history-list)
 389                       (Info-goto-node node)
 390                       (setq doc-found t)))
 391                 (error
 392                  (message "Cannot access Info node %s" node)
 393                  (sit-for 1)
 394                  nil))
 395           (condition-case nil
 396               (progn
 397                 ;; Don't use Info-menu, it forces case-fold-search to t
 398                 (let ((case-fold-search nil))
 399                   (re-search-forward
 400                    (concat "^\\* " (regexp-quote (or (cdr entry) (car entry)))
 401                            ":")))
 402                 (Info-follow-nearest-node)
 403                 (setq found t)
 404                 (if (or prefix suffix)
 405                     (let ((case-fold-search
 406                            (info-lookup->ignore-case topic (car modes)))
 407                           (buffer-read-only nil))
 408                       (goto-char (point-min))
 409                       (re-search-forward
 410                        (concat prefix (regexp-quote (car entry)) suffix))
 411                       (goto-char (match-beginning 0))
 412                       (and (display-color-p) info-lookup-highlight-face
 413                            ;; Search again for ITEM so that the first
 414                            ;; occurrence of ITEM will be highlighted.
 415                            (re-search-forward (regexp-quote (car entry)))
 416                            (let ((start (match-beginning 0))
 417                                  (end (match-end 0)))
 418                              (if (overlayp info-lookup-highlight-overlay)
 419                                  (move-overlay info-lookup-highlight-overlay
 420                                                start end (current-buffer))
 421                                (setq info-lookup-highlight-overlay
 422                                      (make-overlay start end))))
 423                            (overlay-put info-lookup-highlight-overlay
 424                                         'face info-lookup-highlight-face)))))
 425             (error nil)))
 426         (setq doc-spec (cdr doc-spec)))
 427       (setq modes (cdr modes)))
 428     ;; Alert the user if case was munged, and do this after bringing up the
 429     ;; info buffer since that can print messages
 430     (unless (or ignore-case
 431                 (string-equal item (car entry)))
 432       (message "Found in different case: %s" (car entry)))
 433     (when found
 434       (setq Info-history new-Info-history))
 435     (or doc-found
 436         (error "Info documentation for lookup was not found"))
 437     ;; Don't leave the Info buffer if the help item couldn't be looked up.
 438     (if (and info-lookup-other-window-flag found)
 439         (select-window window))))
 440
 441 (defun info-lookup-setup-mode (topic mode)
 442   "Initialize the internal data structure."
 443   (or (info-lookup->initialized topic mode)
 444       (let ((initialized 0)
 445             cell data completions refer-modes Info-history-list)
 446         (if (not (info-lookup->mode-value topic mode))
 447             (message "No %s help available for `%s'" topic mode)
 448           ;; Recursively setup cross references.
 449           ;; But refer only to non-void modes.
 450           (dolist (arg (info-lookup->other-modes topic mode))
 451             (or (info-lookup->initialized topic arg)
 452                 (info-lookup-setup-mode topic arg))
 453             (and (eq (info-lookup->initialized topic arg) t)
 454                  (setq refer-modes (cons arg refer-modes))))
 455           (setq refer-modes (nreverse refer-modes))
 456           ;; Build the full completion alist.
 457           (setq completions
 458                 (nconc (condition-case nil
 459                            (info-lookup-make-completions topic mode)
 460                          (error nil))
 461                        (apply 'append
 462                               (mapcar (lambda (arg)
 463                                         (info-lookup->completions topic arg))
 464                                       refer-modes))))
 465           (setq initialized t))
 466         ;; Update `info-lookup-cache'.
 467         (setq cell (info-lookup->mode-cache topic mode)
 468               data (list initialized completions refer-modes))
 469         (if (not cell)
 470             (setcdr (info-lookup->cache topic)
 471                     (cons (cons mode data) (info-lookup->topic-cache topic)))
 472           (setcdr cell data))
 473         initialized)))
 474
 475 (defun info-lookup-make-completions (topic mode)
 476   "Create a unique alist from all index entries."
 477   (let ((doc-spec (info-lookup->doc-spec topic mode))
 478         (regexp (concat "^\\(" (info-lookup->regexp topic mode)
 479                         "\\)\\([ \t].*\\)?$"))
 480         Info-history-list Info-fontify-maximum-menu-size
 481         node trans entry item prefix result doc-found
 482         (buffer (get-buffer-create " temp-info-look")))
 483     (with-current-buffer buffer
 484       (Info-mode))
 485     (while doc-spec
 486       (setq node (nth 0 (car doc-spec))
 487             trans (cond ((eq (nth 1 (car doc-spec)) nil)
 488                          (lambda (arg)
 489                            (if (string-match regexp arg)
 490                                (match-string 1 arg))))
 491                         ((stringp (nth 1 (car doc-spec)))
 492                          (setq prefix (nth 1 (car doc-spec)))
 493                          (lambda (arg)
 494                            (if (string-match "^\\([^: \t\n]+\\)" arg)
 495                                (concat prefix (match-string 1 arg)))))
 496                         (t (nth 1 (car doc-spec)))))
 497       (with-current-buffer buffer
 498         (message "Processing Info node `%s'..." node)
 499         (when (condition-case nil
 500                   (progn
 501                     (Info-goto-node node)
 502                     (setq doc-found t))
 503                 (error
 504                  (message "Cannot access Info node `%s'" node)
 505                  (sit-for 1)
 506                  nil))
 507           (condition-case nil
 508               (progn
 509                 (goto-char (point-min))
 510                 (and (search-forward "\n* Menu:" nil t)
 511                      (while (re-search-forward "\n\\* \\(.*\\): " nil t)
 512                        (setq entry (match-string 1)
 513                              item (funcall trans entry))
 514                        ;; `trans' can return nil if the regexp doesn't match.
 515                        (when (and item
 516                                   ;; Sometimes there's more than one Menu:
 517                                   (not (string= entry "Menu")))
 518                          (and (info-lookup->ignore-case topic mode)
 519                               (setq item (downcase item)))
 520                          (and (string-equal entry item)
 521                               (setq entry nil))
 522                          (and (or (assoc item result)
 523                                   (setq result (cons (cons item entry)
 524                                                      result))))))))
 525             (error nil))))
 526       (message "Processing Info node `%s'...done" node)
 527       (setq doc-spec (cdr doc-spec)))
 528     (or doc-found
 529         (error "Info documentation for lookup was not found"))
 530     result))
 531
 532 (defun info-lookup-guess-default (topic mode)
 533   "Return a guess for a symbol to look up, based on text around point.
 534 Try all related modes applicable to TOPIC and MODE.
 535 Return nil if there is nothing appropriate in the buffer near point."
 536   (let ((modes (info-lookup->all-modes topic mode))
 537         guess)
 538     (while (and (not guess) modes)
 539       (setq guess (info-lookup-guess-default* topic (car modes))
 540             modes (cdr modes)))
 541     ;; Collapse whitespace characters.
 542     (when guess
 543       (let ((pos 0))
 544         (while (string-match "[ \t\n]+" guess pos)
 545           (setq pos (1+ (match-beginning 0)))
 546           (setq guess (replace-match " " t t guess)))))
 547     guess))
 548
 549 (defun info-lookup-guess-default* (topic mode)
 550   (let ((case-fold-search (info-lookup->ignore-case topic mode))
 551         (rule (or (info-lookup->parse-rule topic mode)
 552                   (info-lookup->regexp topic mode)))
 553         (start (point)) end regexp subexp result)
 554     (save-excursion
 555       (if (symbolp rule)
 556           (setq result (funcall rule))
 557         (if (consp rule)
 558             (setq regexp (car rule)
 559                   subexp (cdr rule))
 560           (setq regexp rule
 561                 subexp 0))
 562         ;; If at start of symbol, don't go back to end of previous one.
 563         (if (save-match-data
 564               (looking-at "[ \t\n]"))
 565             (skip-chars-backward " \t\n"))
 566         (setq end (point))
 567         (while (and (re-search-backward regexp nil t)
 568                     (looking-at regexp)
 569                     (>= (match-end 0) end))
 570           (setq result (match-string subexp)))
 571         (if (not result)
 572             (progn
 573               (goto-char start)
 574               (skip-chars-forward " \t\n")
 575               (and (looking-at regexp)
 576                    (setq result (match-string subexp)))))))
 577     result))
 578
 579 (defun info-lookup-guess-c-symbol ()
 580   "Get the C symbol at point."
 581   (condition-case nil
 582       (progn
 583         (skip-syntax-backward "w_")
 584         (let ((start (point)) prefix name)
 585           ;; Test for a leading `struct', `union', or `enum' keyword
 586           ;; but ignore names like `foo_struct'.
 587           (setq prefix (and (< (skip-chars-backward " \t\n") 0)
 588                             (< (skip-chars-backward "_a-zA-Z0-9") 0)
 589                             (looking-at "\\(struct\\|union\\|enum\\)\\s ")
 590                             (concat (match-string 1) " ")))
 591           (goto-char start)
 592           (and (looking-at "[_a-zA-Z][_a-zA-Z0-9]*")
 593                (setq name (match-string 0)))
 594           ;; Caveat!  Look forward if point is at `struct' etc.
 595           (and (not prefix)
 596                (or (string-equal name "struct")
 597                    (string-equal name "union")
 598                    (string-equal name "enum"))
 599                (looking-at "[a-z]+\\s +\\([_a-zA-Z][_a-zA-Z0-9]*\\)")
 600                (setq prefix (concat name " ")
 601                      name (match-string 1)))
 602           (and (or prefix name)
 603                (concat prefix name))))
 604     (error nil)))
 605
 606 (defun info-lookup-guess-custom-symbol ()
 607   "Get symbol at point in custom buffers."
 608   (condition-case nil
 609       (save-excursion
 610         (let ((case-fold-search t)
 611               (ignored-chars "][()`',:.\" \t\n")
 612               (significant-chars "^][()`',:.\" \t\n")
 613               beg end)
 614           (cond
 615            ((and (memq (get-char-property (point) 'face)
 616                          '(custom-variable-tag custom-variable-tag-face))
 617                    (setq beg (previous-single-char-property-change
 618                               (point) 'face nil (line-beginning-position)))
 619                    (setq end (next-single-char-property-change
 620                               (point) 'face nil (line-end-position)))
 621                    (> end beg))
 622             (subst-char-in-string
 623              ?\s ?\- (buffer-substring-no-properties beg end)))
 624            ((or (and (looking-at (concat "[" significant-chars "]"))
 625                      (save-excursion
 626                        (skip-chars-backward significant-chars)
 627                        (setq beg (point)))
 628                      (skip-chars-forward significant-chars)
 629                      (setq end (point))
 630                      (> end beg))
 631                 (and (looking-at "[ \t\n]")
 632                      (looking-back (concat "[" significant-chars "]"))
 633                      (setq end (point))
 634                      (skip-chars-backward significant-chars)
 635                      (setq beg (point))
 636                      (> end beg))
 637                 (and (skip-chars-forward ignored-chars)
 638                      (setq beg (point))
 639                      (skip-chars-forward significant-chars)
 640                      (setq end (point))
 641                      (> end beg)))
 642             (buffer-substring-no-properties beg end)))))
 643     (error nil)))
 644
 645 ;;;###autoload
 646 (defun info-complete-symbol (&optional mode)
 647   "Perform completion on symbol preceding point."
 648   (interactive)
 649   (info-complete 'symbol
 650                  (or mode
 651                      (if (info-lookup->mode-value
 652                           'symbol (info-lookup-select-mode))
 653                          info-lookup-mode
 654                        (info-lookup-change-mode 'symbol)))))
 655
 656 ;;;###autoload
 657 (defun info-complete-file (&optional mode)
 658   "Perform completion on file preceding point."
 659   (interactive)
 660   (info-complete 'file
 661                  (or mode
 662                      (if (info-lookup->mode-value
 663                           'file (info-lookup-select-mode))
 664                          info-lookup-mode
 665                        (info-lookup-change-mode 'file)))))
 666
 667 (defun info-lookup-completions-at-point (topic mode)
 668   "Try to complete a help item."
 669   (or mode (setq mode (info-lookup-select-mode)))
 670   (when (info-lookup->mode-value topic mode)
 671     (let ((modes (info-lookup-quick-all-modes topic mode))
 672           (start (point))
 673           try)
 674       (while (and (not try) modes)
 675         (setq mode (car modes)
 676               modes (cdr modes)
 677               try (info-lookup-guess-default* topic mode))
 678         (goto-char start))
 679       (when try
 680         (let ((completions (info-lookup->completions topic mode)))
 681           (when completions
 682             (when (info-lookup->ignore-case topic mode)
 683               (setq completions
 684                     (lambda (string pred action)
 685                       (let ((completion-ignore-case t))
 686                         (complete-with-action
 687                          action completions string pred)))))
 688             (save-excursion
 689               ;; Find the original symbol and zap it.
 690               (end-of-line)
 691               (while (and (search-backward try nil t)
 692                           (< start (point))))
 693               (list (match-beginning 0) (match-end 0) completions
 694                     :exclusive 'no))))))))
 695
 696 (defun info-complete (topic mode)
 697   "Try to complete a help item."
 698   (barf-if-buffer-read-only)
 699   (let ((data (info-lookup-completions-at-point topic mode)))
 700     (if (null data)
 701         (error "No %s completion available for `%s' at point" topic mode)
 702       (completion-in-region (nth 0 data) (nth 1 data) (nth 2 data)))))
 703
 704 \f
 705 ;;; Initialize some common modes.
 706
 707 (info-lookup-maybe-add-help
 708  :mode 'c-mode :topic 'symbol
 709  :regexp "\\(struct \\|union \\|enum \\)?[_a-zA-Z][_a-zA-Z0-9]*"
 710  :doc-spec '(("(libc)Function Index" nil
 711               "^[ \t]+-+ \\(Function\\|Macro\\): .*\\<" "\\>")
 712              ;; prefix/suffix has to match things like
 713              ;;   " -- Macro: int F_DUPFD"
 714              ;;   " -- Variable: char * tzname [2]"
 715              ;;   "`DBL_MAX'"    (texinfo @table)
 716              ;; suffix "\\>" is not used because that sends DBL_MAX to
 717              ;; DBL_MAX_EXP ("_" is a non-word char)
 718              ("(libc)Variable Index" nil
 719               "^\\([ \t]+-+ \\(Variable\\|Macro\\): .*\\<\\|`\\)"
 720               "\\( \\|'?$\\)")
 721              ("(libc)Type Index" nil
 722               "^[ \t]+-+ Data Type: \\<" "\\>")
 723              ("(termcap)Var Index" nil
 724               "^[ \t]*`" "'"))
 725  :parse-rule 'info-lookup-guess-c-symbol)
 726
 727 (info-lookup-maybe-add-help
 728  :mode 'c-mode :topic 'file
 729  :regexp "[_a-zA-Z0-9./+-]+"
 730  :doc-spec '(("(libc)File Index")))
 731
 732 (info-lookup-maybe-add-help
 733  :mode 'bison-mode
 734  :regexp "[:;|]\\|%\\([%{}]\\|[_a-z]+\\)\\|YY[_A-Z]+\\|yy[_a-z]+"
 735  :doc-spec '(("(bison)Index" nil
 736               "`" "'"))
 737  :parse-rule "[:;|]\\|%\\([%{}]\\|[_a-zA-Z][_a-zA-Z0-9]*\\)"
 738  :other-modes '(c-mode))
 739
 740 (info-lookup-maybe-add-help
 741  :mode 'makefile-mode
 742  :regexp "\\$[^({]\\|\\.[_A-Z]*\\|[_a-zA-Z][_a-zA-Z0-9-]*"
 743  :doc-spec '(("(make)Name Index" nil
 744               "^[ \t]*`" "'"))
 745  :parse-rule "\\$[^({]\\|\\.[_A-Z]*\\|[_a-zA-Z0-9-]+")
 746
 747 (info-lookup-maybe-add-help
 748  :topic      'symbol
 749  :mode       'makefile-automake-mode
 750  ;; similar regexp/parse-rule as makefile-mode, but also the following
 751  ;; (which have index entries),
 752  ;;   "##" special automake comment
 753  ;;   "+=" append operator, separate from the GNU make one
 754  :regexp     "\\$[^({]\\|\\.[_A-Z]*\\|[_a-zA-Z][_a-zA-Z0-9-]*\\|##\\|\\+="
 755  :parse-rule "\\$[^({]\\|\\.[_A-Z]*\\|[_a-zA-Z0-9-]+\\|##\\|\\+="
 756  :doc-spec   '(
 757                ;; "(automake)Macro Index" is autoconf macros used in
 758                ;; configure.ac, not Makefile.am, so don't have that here.
 759                ("(automake)Variable Index" nil "^[ \t]*`" "'")
 760                ;; In automake 1.4 macros and variables were a combined node.
 761                ("(automake)Macro and Variable Index" nil "^[ \t]*`" "'")
 762                ;; Directives like "if" are in the "General Index".
 763                ;; Prefix "`" since the text for say `+=' isn't always an
 764                ;; @item etc and so not always at the start of a line.
 765                ("(automake)General Index" nil "`" "'")
 766                ;; In automake 1.3 there was just a single "Index" node.
 767                ("(automake)Index" nil "`" "'"))
 768  :other-modes '(makefile-mode))
 769
 770 (info-lookup-maybe-add-help
 771  :mode 'texinfo-mode
 772  :regexp "@\\([a-zA-Z]+\\|[^a-zA-Z]\\)"
 773  :doc-spec '(("(texinfo)Command and Variable Index"
 774               ;; Ignore Emacs commands and prepend a `@'.
 775               (lambda (item)
 776                 (if (string-match "^\\([a-zA-Z]+\\|[^a-zA-Z]\\)\\( .*\\)?$" item)
 777                     (concat "@" (match-string 1 item))))
 778               "`" "[' ]")))
 779
 780 (info-lookup-maybe-add-help
 781  :mode 'm4-mode
 782  :regexp "[_a-zA-Z][_a-zA-Z0-9]*"
 783  :doc-spec '(("(m4)Macro index"))
 784  :parse-rule "[_a-zA-Z0-9]+")
 785
 786 (info-lookup-maybe-add-help
 787  :mode 'autoconf-mode
 788  :regexp "A[CM]_[_A-Z0-9]+"
 789  :doc-spec '(;; Autoconf Macro Index entries are without an "AC_" prefix,
 790              ;; but with "AH_" or "AU_" for those.  So add "AC_" if there
 791              ;; isn't already an "A._".
 792              ("(autoconf)Autoconf Macro Index"
 793               (lambda (item)
 794                 (if (string-match "^A._" item) item (concat "AC_" item)))
 795               "^[ \t]+-+ \\(Macro\\|Variable\\): .*\\<" "\\>")
 796              ;; M4 Macro Index entries are without "AS_" prefixes, and
 797              ;; mostly without "m4_" prefixes.  "dnl" is an exception, not
 798              ;; wanting any prefix.  So AS_ is added back to upper-case
 799              ;; names (if needed), m4_ to others which don't already an m4_.
 800              ("(autoconf)M4 Macro Index"
 801               (lambda (item)
 802                 (let ((case-fold-search nil))
 803                   (cond ((or (string-equal item "dnl")
 804                              (string-match "^m4_" item)
 805                              ;; Autoconf 2.62 index includes some macros
 806                              ;; (e.g., AS_HELP_STRING), so avoid prefixing.
 807                              (string-match "^AS_" item))
 808                          item)
 809                         ((string-match "^[A-Z0-9_]+$" item)
 810                          (concat "AS_" item))
 811                         (t
 812                          (concat "m4_" item)))))
 813               "^[ \t]+-+ Macro: .*\\<" "\\>")
 814              ;; Autotest Macro Index entries are without "AT_".
 815              ("(autoconf)Autotest Macro Index" "AT_"
 816               "^[ \t]+-+ Macro: .*\\<" "\\>")
 817              ;; This is for older versions (probably pre autoconf 2.5x):
 818              ("(autoconf)Macro Index" "AC_"
 819               "^[ \t]+-+ \\(Macro\\|Variable\\): .*\\<" "\\>")
 820              ;; Automake has index entries for its notes on various autoconf
 821              ;; macros (eg. AC_PROG_CC).  Ensure this is after the autoconf
 822              ;; index, so as to prefer the autoconf docs.
 823              ("(automake)Macro and Variable Index" nil
 824               "^[ \t]*`" "'"))
 825  ;; Autoconf symbols are M4 macros.  Thus use M4's parser.
 826  :parse-rule 'ignore
 827  :other-modes '(m4-mode))
 828
 829 (info-lookup-maybe-add-help
 830  :mode 'awk-mode
 831  :regexp "[_a-zA-Z]+"
 832  :doc-spec '(("(gawk)Index"
 833               (lambda (item)
 834                 (let ((case-fold-search nil))
 835                   (cond
 836                    ;; `BEGIN' and `END'.
 837                    ((string-match "^\\([A-Z]+\\) special pattern\\b" item)
 838                     (match-string 1 item))
 839                    ;; `if', `while', `do', ...
 840                    ((string-match "^\\([a-z]+\\) statement\\b" item)
 841                     (if (not (string-equal (match-string 1 item) "control"))
 842                         (match-string 1 item)))
 843                    ;; `NR', `NF', ...
 844                    ((string-match "^[A-Z]+$" item)
 845                     item)
 846                    ;; Built-in functions (matches to many entries).
 847                    ((string-match "^[a-z]+$" item)
 848                     item))))
 849               "`" "\\([ \t]*([^)]*)\\)?'")))
 850
 851 (info-lookup-maybe-add-help
 852  :mode 'perl-mode
 853  :regexp "[$@%][^a-zA-Z]\\|\\$\\^[A-Z]\\|[$@%]?[a-zA-Z][_a-zA-Z0-9]*"
 854  :doc-spec '(("(perl5)Function Index"
 855               (lambda (item)
 856                 (if (string-match "^\\([a-zA-Z0-9]+\\)" item)
 857                     (match-string 1 item)))
 858               "^" "\\b")
 859              ("(perl5)Variable Index"
 860               (lambda (item)
 861                 ;; Work around bad formatted array variables.
 862                 (let ((sym (cond ((or (string-match "^\\$\\(.\\|@@\\)$" item)
 863                                       (string-match "^\\$\\^[A-Z]$" item))
 864                                   item)
 865                                  ((string-match
 866                                    "^\\([$%@]\\|@@\\)?[_a-zA-Z0-9]+" item)
 867                                   (match-string 0 item))
 868                                  (t ""))))
 869                   (if (string-match "@@" sym)
 870                       (setq sym (concat (substring sym 0 (match-beginning 0))
 871                                         (substring sym (1- (match-end 0))))))
 872                   (if (string-equal sym "") nil sym)))
 873               "^" "\\b"))
 874  :parse-rule "[$@%]?\\([_a-zA-Z0-9]+\\|[^a-zA-Z]\\)")
 875
 876 (info-lookup-maybe-add-help
 877  :mode 'cperl-mode
 878  :regexp "[$@%][^a-zA-Z]\\|\\$\\^[A-Z]\\|[$@%]?[a-zA-Z][_a-zA-Z0-9]*"
 879  :other-modes '(perl-mode))
 880
 881 (info-lookup-maybe-add-help
 882  :mode 'latex-mode
 883  :regexp "\\\\\\([a-zA-Z]+\\|[^a-zA-Z]\\)"
 884  :doc-spec `((,(if (Info-find-file "latex2e" t)
 885                    ;; From http://home.gna.org/latexrefman
 886                    "(latex2e)Command Index"
 887                  "(latex)Command Index")
 888               nil "`" "\\({[^}]*}\\)?'")))
 889
 890 (info-lookup-maybe-add-help
 891  :mode 'emacs-lisp-mode
 892  :regexp "[^][()`',\" \t\n]+"
 893  :doc-spec '(;; Commands with key sequences appear in nodes as `foo' and
 894              ;; those without as `M-x foo'.
 895              ("(emacs)Command Index"  nil "`\\(M-x[ \t\n]+\\)?" "'")
 896              ;; Variables normally appear in nodes as just `foo'.
 897              ("(emacs)Variable Index" nil "`" "'")
 898              ;; Almost all functions, variables, etc appear in nodes as
 899              ;; " -- Function: foo" etc.  A small number of aliases and
 900              ;; symbols appear only as `foo', and will miss out on exact
 901              ;; positions.  Allowing `foo' would hit too many false matches
 902              ;; for things that should go to Function: etc, and those latter
 903              ;; are much more important.  Perhaps this could change if some
 904              ;; sort of fallback match scheme existed.
 905              ("(elisp)Index"          nil "^ -+ .*: " "\\( \\|$\\)")))
 906
 907 ;; docstrings talk about elisp, so have apropos-mode follow emacs-lisp-mode
 908 (info-lookup-maybe-add-help
 909  :mode 'apropos-mode
 910  :regexp "[^][()`',\" \t\n]+" ;; same as emacs-lisp-mode above
 911  :other-modes '(emacs-lisp-mode))
 912
 913 (info-lookup-maybe-add-help
 914  :mode 'lisp-interaction-mode
 915  :regexp "[^][()`',\" \t\n]+"
 916  :parse-rule 'ignore
 917  :other-modes '(emacs-lisp-mode))
 918
 919 (info-lookup-maybe-add-help
 920  :mode 'lisp-mode
 921  :regexp "[^()`',\" \t\n]+"
 922  :parse-rule 'ignore
 923  :other-modes '(emacs-lisp-mode))
 924
 925 (info-lookup-maybe-add-help
 926  :mode 'scheme-mode
 927  :regexp "[^()`',\" \t\n]+"
 928  :ignore-case t
 929  ;; Aubrey Jaffer's rendition from <URL:ftp://ftp-swiss.ai.mit.edu/pub/scm>
 930  :doc-spec '(("(r5rs)Index" nil
 931               "^[ \t]+-+ [^:]+:[ \t]*" "\\b")))
 932
 933 (info-lookup-maybe-add-help
 934  :mode 'octave-mode
 935  :regexp "[_a-zA-Z0-9]+\\|\\s.+\\|[-!=^|*/.\\,><~&+]\\{1,3\\}\\|[][();,\"']"
 936  :doc-spec '(("(octave)Function Index" nil
 937               "^ -+ [^:]+:[ ]+\\(\\[[^=]*=[ ]+\\)?" nil)
 938              ("(octave)Variable Index" nil "^ -+ [^:]+:[ ]+" nil)
 939              ("(octave)Operator Index" nil nil nil)
 940              ;; Catch lines of the form "xyz statement"
 941              ("(octave)Concept Index"
 942               (lambda (item)
 943                 (cond
 944                  ((string-match "^\\([A-Z]+\\) statement\\b" item)
 945                     (match-string 1 item))
 946                  (t nil)))
 947               nil; "^ -+ [^:]+:[ ]+" don't think this prefix is useful here.
 948               nil)))
 949
 950 (info-lookup-maybe-add-help
 951  :mode 'maxima-mode
 952  :ignore-case t
 953  :regexp "[a-zA-Z0-9_%]+"
 954  :doc-spec '( ("(maxima)Function and Variable Index" nil
 955                "^ -+ [^:]+:[ ]+\\(\\[[^=]*=[ ]+\\)?" nil)))
 956
 957 (info-lookup-maybe-add-help
 958  :mode 'inferior-maxima-mode
 959  :regexp "[a-zA-Z0-9_%]+"
 960  :other-modes '(maxima-mode))
 961
 962 ;; coreutils and bash builtins overlap in places, eg. printf, so there's a
 963 ;; question which should come first.  Some of the coreutils descriptions are
 964 ;; more detailed, but if bash is usually /bin/sh on a GNU system then the
 965 ;; builtins will be what's normally run.
 966 ;;
 967 ;; Maybe special variables like $? should be matched as $?, not just ?.
 968 ;; This would avoid a clash between variable $! and negation !, or variable
 969 ;; $# and comment # (though comment # is not currently indexed in bash).
 970 ;; Unfortunately if $? etc is the symbol, then we wouldn't be taken to the
 971 ;; exact spot in the relevant node, since the bash manual has just `?' etc
 972 ;; there.  Maybe an extension to the prefix/suffix scheme could help this.
 973
 974 (info-lookup-maybe-add-help
 975  :mode 'sh-mode :topic 'symbol
 976  ;; bash has "." and ":" in its index, but those chars will probably never
 977  ;; work in info, so don't bother matching them in the regexp.
 978  :regexp "\\([a-zA-Z0-9_-]+\\|[!{}@*#?$]\\|\\[\\[?\\|]]?\\)"
 979  :doc-spec '(("(bash)Builtin Index"       nil "^`" "[ .']")
 980              ("(bash)Reserved Word Index" nil "^`" "[ .']")
 981              ("(bash)Variable Index"      nil "^`" "[ .']")
 982
 983              ;; coreutils (version 4.5.10) doesn't have a separate program
 984              ;; index, so exclude extraneous stuff (most of it) by demanding
 985              ;; "[a-z]+" in the trans-func.
 986              ;; coreutils version 8.1 has node "Concept Index" and past
 987              ;; versions have node "Index", look for both, whichever is
 988              ;; absent is quietly ignored
 989              ("(coreutils)Index"
 990               (lambda (item) (if (string-match "\\`[a-z]+\\'" item) item)))
 991              ("(coreutils)Concept Index"
 992               (lambda (item) (if (string-match "\\`[a-z]+\\'" item) item)))
 993
 994              ;; diff (version 2.8.1) has only a few programs, index entries
 995              ;; are things like "foo invocation".
 996              ("(diff)Index"
 997               (lambda (item)
 998                 (if (string-match "\\`\\([a-z]+\\) invocation\\'" item)
 999                     (match-string 1 item))))
1000              ;; there's no plain "sed" index entry as such, mung another
1001              ;; hopefully unique one to get to the invocation section
1002              ("(sed)Concept Index"
1003               (lambda (item)
1004                 (if (string-equal item "Standard input, processing as input")
1005                     "sed")))
1006              ;; there's no plain "awk" or "gawk" index entries, mung other
1007              ;; hopefully unique ones to get to the command line options
1008              ("(gawk)Index"
1009               (lambda (item)
1010                 (cond ((string-equal item "gawk, extensions, disabling")
1011                        "awk")
1012                       ((string-equal item "gawk, versions of, information about, printing")
1013                        "gawk"))))))
1014
1015 ;; This misses some things which occur as node names but not in the
1016 ;; index.  Unfortunately it also picks up the wrong one of multiple
1017 ;; entries for the same term in some cases.  --fx
1018 (info-lookup-maybe-add-help
1019  :mode 'cfengine-mode
1020  :regexp "[[:alnum:]_]+\\(?:()\\)?"
1021  :doc-spec '(("(cfengine-Reference)Variable Index"
1022               (lambda (item)
1023                 ;; Index entries may be like `IsPlain()'
1024                 (if (string-match "\\([[:alnum:]_]+\\)()" item)
1025                     (match-string 1 item)
1026                   item))
1027               ;; This gets functions in evaluated classes.  Other
1028               ;; possible patterns don't seem to work too well.
1029               "`" "(")))
1030
1031 (info-lookup-maybe-add-help
1032  :mode 'Custom-mode
1033  :ignore-case t
1034  :regexp "[^][()`',:\" \t\n]+"
1035  :parse-rule 'info-lookup-guess-custom-symbol
1036  :other-modes '(emacs-lisp-mode))
1037
1038 (info-lookup-maybe-add-help
1039  :mode 'help-mode
1040  :regexp "[^][()`',:\" \t\n]+"
1041  :other-modes '(emacs-lisp-mode))
1042 \f
1043 (provide 'info-look)
1044
1045 ;;; info-look.el ends here