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 Ralph Schleicher.
   5
   6 ;; Author: Ralph Schleicher <rs@purple.UL.BaWue.DE>
   7 ;; Keywords: help languages
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software; you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation; either version 2, or (at your option)
  14 ;; any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  23 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  24 ;; Boston, MA 02111-1307, USA.
  25
  26 ;;; Code:
  27
  28 (require 'info)
  29
  30 (defvar info-lookup-mode nil
  31   "*Symbol of the current buffer's help mode.
  32 Provide help according to the buffer's major mode if value is nil.
  33 Automatically becomes buffer local when set in any fashion.")
  34 (make-variable-buffer-local 'info-lookup-mode)
  35
  36 (defvar info-lookup-other-window-flag t
  37   "*Non-nil means pop up the Info buffer in another window.")
  38
  39 (defvar info-lookup-highlight-face 'highlight
  40   "*Face for highlighting looked up help items.
  41 Setting this variable to nil disables highlighting.")
  42
  43 (defvar info-lookup-highlight-overlay nil
  44   "Overlay object used for highlighting.")
  45
  46 (defvar info-lookup-history nil
  47   "History of previous input lines.")
  48
  49 (defvar info-lookup-alist '((symbol . info-lookup-symbol-alist)
  50                             (file . info-lookup-file-alist))
  51   "*Alist of known help topics.
  52 Cons cells are of the form
  53
  54     (HELP-TOPIC . VARIABLE)
  55
  56 HELP-TOPIC is the symbol of a help topic.
  57 VARIABLE is a variable storing HELP-TOPIC's public data.
  58  Value is an alist with elements of the form
  59
  60     (HELP-MODE REGEXP IGNORE-CASE DOC-SPEC PARSE-RULE OTHER-MODES)
  61
  62 HELP-MODE is a mode's symbol.
  63 REGEXP is a regular expression matching those help items whose
  64  documentation can be looked up via DOC-SPEC.
  65 IGNORE-CASE is non-nil if help items are case insensitive.
  66 DOC-SPEC is a list of documentation specifications of the form
  67
  68     (INFO-NODE TRANS-FUNC PREFIX SUFFIX)
  69
  70 INFO-NODE is the name (including file name part) of an Info index.
  71 TRANS-FUNC is a function translating index entries into help items;
  72  nil means add only those index entries matching REGEXP, a string
  73  means prepend string to the first word of all index entries.
  74 PREFIX and SUFFIX are parts of a regular expression.  If one of
  75  them is non-nil then search the help item's Info node for the
  76  first occurrence of the regular expression `PREFIX ITEM SUFFIX'.
  77  ITEM will be highlighted with `info-lookup-highlight-face' if this
  78  variable is not nil.
  79 PARSE-RULE is either the symbol name of a function or a regular
  80  expression for guessing the default help item at point.  Fuzzy
  81  regular expressions like \"[_a-zA-Z0-9]+\" do a better job if
  82  there are no clear delimiters; do not try to write too complex
  83  expressions.  PARSE-RULE defaults to REGEXP.
  84 OTHER-MODES is a list of cross references to other help modes.")
  85
  86 (defsubst info-lookup->topic-value (topic)
  87   (symbol-value (cdr (assoc topic info-lookup-alist))))
  88
  89 (defsubst info-lookup->mode-value (topic mode)
  90   (assoc mode (info-lookup->topic-value topic)))
  91
  92 (defsubst info-lookup->regexp (topic mode)
  93   (nth 1 (info-lookup->mode-value topic mode)))
  94
  95 (defsubst info-lookup->ignore-case (topic mode)
  96   (nth 2 (info-lookup->mode-value topic mode)))
  97
  98 (defsubst info-lookup->doc-spec (topic mode)
  99   (nth 3 (info-lookup->mode-value topic mode)))
 100
 101 (defsubst info-lookup->parse-rule (topic mode)
 102   (nth 4 (info-lookup->mode-value topic mode)))
 103
 104 (defsubst info-lookup->other-modes (topic mode)
 105   (nth 5 (info-lookup->mode-value topic mode)))
 106
 107 (defvar info-lookup-cache nil
 108   "Cache storing data maintained automatically by the program.
 109 Value is an alist with cons cell of the form
 110
 111     (HELP-TOPIC . ((HELP-MODE INITIALIZED COMPLETIONS REFER-MODES) ...))
 112
 113 HELP-TOPIC is the symbol of a help topic.
 114 HELP-MODE is a mode's symbol.
 115 INITIALIZED is nil if HELP-MODE is uninitialized, t if
 116  HELP-MODE is initialized, and `0' means HELP-MODE is
 117  initialized but void.
 118 COMPLETIONS is an alist of documented help items.
 119 REFER-MODES is a list of other help modes to use.")
 120
 121 (defsubst info-lookup->cache (topic)
 122   (or (assoc topic info-lookup-cache)
 123       (car (setq info-lookup-cache
 124                  (cons (cons topic nil)
 125                        info-lookup-cache)))))
 126
 127 (defsubst info-lookup->topic-cache (topic)
 128   (cdr (info-lookup->cache topic)))
 129
 130 (defsubst info-lookup->mode-cache (topic mode)
 131   (assoc mode (info-lookup->topic-cache topic)))
 132
 133 (defsubst info-lookup->initialized (topic mode)
 134   (nth 1 (info-lookup->mode-cache topic mode)))
 135
 136 (defsubst info-lookup->completions (topic mode)
 137   (or (info-lookup->initialized topic mode)
 138       (info-lookup-setup-mode topic mode))
 139   (nth 2 (info-lookup->mode-cache topic mode)))
 140
 141 (defsubst info-lookup->refer-modes (topic mode)
 142   (or (info-lookup->initialized topic mode)
 143       (info-lookup-setup-mode topic mode))
 144   (nth 3 (info-lookup->mode-cache topic mode)))
 145
 146 (defsubst info-lookup->all-modes (topic mode)
 147   (cons mode (info-lookup->refer-modes topic mode)))
 148
 149 (defvar info-lookup-symbol-alist
 150   '((autoconf-mode
 151      "A[CM]_[_A-Z0-9]+" nil
 152      (("(autoconf)Macro Index" "AC_"
 153        "^[ \t]+- \\(Macro\\|Variable\\): .*\\<" "\\>")
 154       ("(automake)Index" nil
 155        "^[ \t]*`" "'"))
 156      ;; Autoconf symbols are M4 macros.  Thus use M4's parser.
 157      ignore
 158      (m4-mode))
 159     (bison-mode
 160      "[:;|]\\|%\\([%{}]\\|[_a-z]+\\)\\|YY[_A-Z]+\\|yy[_a-z]+" nil
 161      (("(bison)Index" nil
 162        "`" "'"))
 163      "[:;|]\\|%\\([%{}]\\|[_a-zA-Z][_a-zA-Z0-9]*\\)"
 164      (c-mode))
 165     (c-mode
 166      "\\(struct \\|union \\|enum \\)?[_a-zA-Z][_a-zA-Z0-9]*" nil
 167      (("(libc)Function Index" nil
 168        "^[ \t]+- \\(Function\\|Macro\\): .*\\<" "\\>")
 169       ("(libc)Variable Index" nil
 170        "^[ \t]+- \\(Variable\\|Macro\\): .*\\<" "\\>")
 171       ("(libc)Type Index" nil
 172        "^[ \t]+- Data Type: \\<" "\\>")
 173       ("(termcap)Var Index" nil
 174        "^[ \t]*`" "'"))
 175      info-lookup-guess-c-symbol)
 176     (m4-mode
 177      "[_a-zA-Z][_a-zA-Z0-9]*" nil
 178      (("(m4)Macro index"))
 179      "[_a-zA-Z0-9]+")
 180     (makefile-mode
 181      "\\$[^({]\\|\\.[_A-Z]*\\|[_a-zA-Z][_a-zA-Z0-9-]*" nil
 182      (("(make)Name Index" nil
 183        "^[ \t]*`" "'"))
 184      "\\$[^({]\\|\\.[_A-Z]*\\|[_a-zA-Z0-9-]+")
 185     (texinfo-mode
 186      "@\\([a-zA-Z]+\\|[^a-zA-Z]\\)" nil
 187      (("(texinfo)Command and Variable Index"
 188        ;; Ignore Emacs commands and prepend a `@'.
 189        (lambda (item)
 190          (if (string-match "^\\([a-zA-Z]+\\|[^a-zA-Z]\\)\\( .*\\)?$" item)
 191              (concat "@" (match-string 1 item))))
 192        "`" "'"))))
 193   "*Alist of help specifications for symbol names.
 194 See the documentation of the variable `info-lookup-alist' for more details.")
 195
 196 (defvar info-lookup-file-alist
 197   '((c-mode
 198      "[_a-zA-Z0-9./+-]+" nil
 199      (("(libc)File Index"))))
 200   "*Alist of help specifications for file names.
 201 See the documentation of the variable `info-lookup-alist' for more details.")
 202
 203 ;;;###autoload
 204 (defun info-lookup-reset ()
 205   "Throw away all cached data.
 206 This command is useful if the user wants to start at the beginning without
 207 quitting Emacs, for example, after some Info documents were updated on the
 208 system."
 209   (interactive)
 210   (setq info-lookup-cache nil))
 211
 212 ;;;###autoload
 213 (defun info-lookup-symbol (symbol &optional mode)
 214   "Display the documentation of a symbol.
 215 If called interactively, SYMBOL will be read from the mini-buffer.
 216 Prefix argument means unconditionally insert the default symbol name
 217 into the mini-buffer so that it can be edited.
 218 The default symbol is the one found at point."
 219   (interactive
 220    (info-lookup-interactive-arguments 'symbol))
 221   (info-lookup 'symbol symbol mode))
 222
 223 ;;;###autoload
 224 (defun info-lookup-file (file &optional mode)
 225   "Display the documentation of a file.
 226 If called interactively, FILE will be read from the mini-buffer.
 227 Prefix argument means unconditionally insert the default file name
 228 into the mini-buffer so that it can be edited.
 229 The default file name is the one found at point."
 230   (interactive
 231    (info-lookup-interactive-arguments 'file))
 232   (info-lookup 'file file mode))
 233
 234 (defun info-lookup-interactive-arguments (topic)
 235   "Return default value and help mode for help topic TOPIC."
 236   (let* ((mode (if (info-lookup->mode-value
 237                     topic (or info-lookup-mode major-mode))
 238                    (or info-lookup-mode major-mode)
 239                  (info-lookup-change-mode topic)))
 240          (completions (info-lookup->completions topic mode))
 241          (default (info-lookup-guess-default topic mode))
 242          (input (if (or current-prefix-arg (not (assoc default completions)))
 243                     default))
 244          (completion-ignore-case (info-lookup->ignore-case topic mode))
 245          (enable-recursive-minibuffers t)
 246          (value (completing-read
 247                  (if (and default (not input))
 248                      (format "Describe %s (default %s): " topic default)
 249                    (format "Describe %s: " topic))
 250                  completions nil nil input 'info-lookup-history)))
 251     (list (if (equal value "") default value) mode)))
 252
 253 (defun info-lookup-change-mode (topic)
 254   (let* ((completions (mapcar (lambda (arg)
 255                                 (cons (symbol-name (car arg)) (car arg)))
 256                               (info-lookup->topic-value topic)))
 257          (mode (completing-read
 258                 (format "Use %s help mode: " topic)
 259                 completions nil t nil 'info-lookup-history)))
 260     (or (setq mode (cdr (assoc mode completions)))
 261         (error "No %s help available" topic))
 262     (or (info-lookup->mode-value topic mode)
 263         (error "No %s help available for `%s'" topic mode))
 264     (setq info-lookup-mode mode)))
 265
 266 (defun info-lookup (topic item mode)
 267   "Display the documentation of a help item."
 268   (if (not mode)
 269       (setq mode (or info-lookup-mode major-mode)))
 270   (or (info-lookup->mode-value topic mode)
 271       (error "No %s help available for `%s'" topic mode))
 272   (let ((entry (or (assoc (if (info-lookup->ignore-case topic mode)
 273                               (downcase item) item)
 274                           (info-lookup->completions topic mode))
 275                    (error "Not documented as a %s: %s" topic (or item ""))))
 276         (modes (info-lookup->all-modes topic mode))
 277         (window (selected-window))
 278         found doc-spec node prefix suffix)
 279     (if (not info-lookup-other-window-flag)
 280         (info)
 281       (save-window-excursion (info))
 282       (switch-to-buffer-other-window "*info*"))
 283     (while (and (not found) modes)
 284       (setq doc-spec (info-lookup->doc-spec topic (car modes)))
 285       (while (and (not found) doc-spec)
 286         (setq node (nth 0 (car doc-spec))
 287               prefix (nth 2 (car doc-spec))
 288               suffix (nth 3 (car doc-spec)))
 289         (condition-case nil
 290             (progn
 291               (Info-goto-node node)
 292               (Info-menu (or (cdr entry) item))
 293               (setq found t)
 294               (if (or prefix suffix)
 295                   (let ((case-fold-search
 296                          (info-lookup->ignore-case topic (car modes)))
 297                         (buffer-read-only nil))
 298                     (goto-char (point-min))
 299                     (re-search-forward
 300                      (concat prefix (regexp-quote item) suffix))
 301                     (goto-char (match-beginning 0))
 302                     (and window-system info-lookup-highlight-face
 303                          ;; Search again for ITEM so that the first
 304                          ;; occurence of ITEM will be highlighted.
 305                          (re-search-forward (regexp-quote item))
 306                          (let ((start (match-beginning 0))
 307                                (end (match-end 0)))
 308                            (if (overlayp info-lookup-highlight-overlay)
 309                                (move-overlay info-lookup-highlight-overlay
 310                                              start end (current-buffer))
 311                              (setq info-lookup-highlight-overlay
 312                                    (make-overlay start end))))
 313                          (overlay-put info-lookup-highlight-overlay
 314                                       'face info-lookup-highlight-face)))))
 315           (error nil))
 316         (setq doc-spec (cdr doc-spec)))
 317       (setq modes (cdr modes)))
 318     ;; Don't leave the Info buffer if the help item couldn't be looked up.
 319     (if (and info-lookup-other-window-flag found)
 320         (select-window window))))
 321
 322 (defun info-lookup-setup-mode (topic mode)
 323   "Initialize the internal data structure."
 324   (or (info-lookup->initialized topic mode)
 325       (let (cell data (initialized 0) completions refer-modes)
 326         (if (not (info-lookup->mode-value topic mode))
 327             (message "No %s help available for `%s'" topic mode)
 328           ;; Recursively setup cross references.
 329           ;; But refer only to non-void modes.
 330           (mapcar (lambda (arg)
 331                     (or (info-lookup->initialized topic arg)
 332                         (info-lookup-setup-mode topic arg))
 333                     (and (eq (info-lookup->initialized topic arg) t)
 334                          (setq refer-modes (cons arg refer-modes))))
 335                   (info-lookup->other-modes topic mode))
 336           (setq refer-modes (nreverse refer-modes))
 337           ;; Build the full completion alist.
 338           (setq completions
 339                 (nconc (info-lookup-make-completions topic mode)
 340                        (apply 'append
 341                               (mapcar (lambda (arg)
 342                                         (info-lookup->completions topic arg))
 343                                       refer-modes))))
 344           (setq initialized t))
 345         ;; Update `info-lookup-cache'.
 346         (setq cell (info-lookup->mode-cache topic mode)
 347               data (list initialized completions refer-modes))
 348         (if (not cell)
 349             (setcdr (info-lookup->cache topic)
 350                     (cons (cons mode data) (info-lookup->topic-cache topic)))
 351           (setcdr cell data))
 352         initialized)))
 353
 354 (defun info-lookup-make-completions (topic mode)
 355   "Create a unique alist from all index entries."
 356   (condition-case nil
 357       (let ((doc-spec (info-lookup->doc-spec topic mode))
 358             (regexp (concat "^\\(" (info-lookup->regexp topic mode)
 359                             "\\)\\([ \t].*\\)?$"))
 360             node trans entry item prefix result)
 361         (save-window-excursion
 362           (info)
 363           (while doc-spec
 364             (setq node (nth 0 (car doc-spec))
 365                   trans (cond ((eq (nth 1 (car doc-spec)) nil)
 366                                (lambda (arg)
 367                                  (if (string-match regexp arg)
 368                                      (match-string 1 arg))))
 369                               ((stringp (nth 1 (car doc-spec)))
 370                                (setq prefix (nth 1 (car doc-spec)))
 371                                (lambda (arg)
 372                                  (if (string-match "^\\([^: \t\n]+\\)" arg)
 373                                      (concat prefix (match-string 1 arg)))))
 374                               (t (nth 1 (car doc-spec)))))
 375             (message "Processing Info node \"%s\"..." node)
 376             (Info-goto-node node)
 377             (goto-char (point-min))
 378             (and (search-forward "\n* Menu:" nil t)
 379                  (while (re-search-forward "\n\\* \\([^:\t\n]*\\):" nil t)
 380                    (setq entry (match-string 1)
 381                          item (funcall trans entry))
 382                    (and (info-lookup->ignore-case topic mode)
 383                         (setq item (downcase item)))
 384                    (and (string-equal entry item)
 385                         (setq entry nil))
 386                    (or (assoc item result)
 387                        (setq result (cons (cons item entry) result)))))
 388             (message "Processing Info node \"%s\"... done" node)
 389             (setq doc-spec (cdr doc-spec)))
 390           (Info-directory))
 391         result)
 392     (error nil)))
 393
 394 (defun info-lookup-guess-default (topic mode)
 395   "Pick up default item at point (with favor to look back).
 396 Return nil if there is nothing appropriate."
 397   (let ((modes (info-lookup->all-modes topic mode))
 398         (start (point)) guess whitespace)
 399     (while (and (not guess) modes)
 400       (setq guess (info-lookup-guess-default* topic (car modes))
 401             modes (cdr modes))
 402       (goto-char start))
 403     ;; Collapse whitespace characters.
 404     (and guess (concat (delete nil (mapcar (lambda (ch)
 405                                              (if (or (char-equal ch ? )
 406                                                      (char-equal ch ?\t)
 407                                                      (char-equal ch ?\n))
 408                                                  (if (not whitespace)
 409                                                      (setq whitespace ? ))
 410                                                (setq whitespace nil) ch))
 411                                            guess))))))
 412
 413 (defun info-lookup-guess-default* (topic mode)
 414   (let ((case-fold-search (info-lookup->ignore-case topic mode))
 415         (rule (or (info-lookup->parse-rule topic mode)
 416                   (info-lookup->regexp topic mode)))
 417         (start (point)) end regexp subexp result)
 418     (if (symbolp rule)
 419         (setq result (funcall rule))
 420       (if (consp rule)
 421           (setq regexp (car rule)
 422                 subexp (cdr rule))
 423         (setq regexp rule
 424               subexp 0))
 425       (skip-chars-backward " \t\n") (setq end (point))
 426       (while (and (re-search-backward regexp nil t)
 427                   (looking-at regexp)
 428                   (>= (match-end 0) end))
 429         (setq result (match-string subexp)))
 430       (if (not result)
 431           (progn
 432             (goto-char start)
 433             (skip-chars-forward " \t\n")
 434             (and (looking-at regexp)
 435                  (setq result (match-string subexp))))))
 436     result))
 437
 438 (defun info-lookup-guess-c-symbol ()
 439   "Get the C symbol at point."
 440   (condition-case nil
 441       (progn
 442         (backward-sexp)
 443         (let ((start (point)) prefix name)
 444           ;; Test for a leading `struct', `union', or `enum' keyword
 445           ;; but ignore names like `foo_struct'.
 446           (setq prefix (and (< (skip-chars-backward " \t\n") 0)
 447                             (< (skip-chars-backward "_a-zA-Z0-9") 0)
 448                             (looking-at "\\(struct\\|union\\|enum\\)\\s ")
 449                             (concat (match-string 1) " ")))
 450           (goto-char start)
 451           (and (looking-at "[_a-zA-Z][_a-zA-Z0-9]*")
 452                (setq name (match-string 0)))
 453           ;; Caveat!  Look forward if point is at `struct' etc.
 454           (and (not prefix)
 455                (or (string-equal name "struct")
 456                    (string-equal name "union")
 457                    (string-equal name "enum"))
 458                (looking-at "[a-z]+\\s +\\([_a-zA-Z][_a-zA-Z0-9]*\\)")
 459                (setq prefix (concat name " ")
 460                      name (match-string 1)))
 461           (and (or prefix name)
 462                (concat prefix name))))
 463     (error nil)))
 464
 465 ;;;###autoload
 466 (defun info-complete-symbol (&optional mode)
 467   "Perform completion on symbol preceding point."
 468   (interactive)
 469   (info-complete 'symbol
 470                  (or mode
 471                      (if (info-lookup->mode-value
 472                           'symbol (or info-lookup-mode major-mode))
 473                          (or info-lookup-mode major-mode)
 474                        (info-lookup-change-mode 'symbol)))))
 475
 476 ;;;###autoload
 477 (defun info-complete-file (&optional mode)
 478   "Perform completion on file preceding point."
 479   (interactive
 480    (list (if (info-lookup->mode-value
 481               'file (or info-lookup-mode major-mode))
 482              (or info-lookup-mode major-mode)
 483            (info-lookup-change-mode 'file))))
 484   (info-complete 'file mode))
 485
 486 (defun info-complete (topic mode)
 487   "Try to complete a help item."
 488   (barf-if-buffer-read-only)
 489   (if (not mode)
 490       (setq mode (or info-lookup-mode major-mode)))
 491   (or (info-lookup->mode-value topic mode)
 492       (error "No %s completion available for `%s'" topic mode))
 493   (let ((modes (info-lookup->all-modes topic mode))
 494         (start (point)) try completion)
 495     (while (and (not try) modes)
 496       (setq mode (car modes)
 497             modes (cdr modes)
 498             try (info-lookup-guess-default* topic mode))
 499       (goto-char start))
 500     (and (not try)
 501          (error "Found no %s to complete" topic))
 502     (setq completion (try-completion
 503                       try (info-lookup->completions topic mode)))
 504     (cond ((not completion)
 505            (ding))
 506           ((stringp completion)
 507            (delete-region (- start (length try)) start)
 508            (insert completion)))))
 509
 510 (provide 'info-look)
 511
 512 ;;; info-look.el ends here