lisp/view.el

   1 ;;; view.el --- peruse file or buffer without editing
   2
   3 ;; Copyright (C) 1985, 1989, 1994, 1995, 1997, 2000, 2001, 2002,
   4 ;;   2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
   5
   6 ;; Author: K. Shane Hartman
   7 ;; Maintainer: Inge Frick <inge@nada.kth.se>
   8 ;; Keywords: files
   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, or (at your option)
  15 ;; 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; see the file COPYING.  If not, write to the
  24 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  25 ;; Boston, MA 02110-1301, USA.
  26
  27 ;;; Commentary:
  28
  29 ;; This package provides the `view' minor mode documented in the Emacs
  30 ;; user's manual.
  31 ;; View mode entry and exit is done through the functions view-mode-enter
  32 ;; and view-mode-exit.  Use these functions to enter or exit view-mode from
  33 ;; emacs lisp programs.
  34 ;; We use both view- and View- as prefix for symbols.  View- is used as
  35 ;; prefix for commands that have a key binding.  view- is used for commands
  36 ;; without key binding.  The purpose of this is to make it easier for a
  37 ;; user to use command name completion.
  38
  39 ;;; Suggested key bindings:
  40 ;;
  41 ;; (define-key ctl-x-4-map "v" 'view-file-other-window)  ; ^x4v
  42 ;; (define-key ctl-x-5-map "v" 'view-file-other-frame)  ; ^x5v
  43 ;;
  44 ;; You could also bind view-file, view-buffer, view-buffer-other-window and
  45 ;; view-buffer-other-frame to keys.
  46 \f
  47 ;;; Code:
  48
  49 (defgroup view nil
  50   "Peruse file or buffer without editing."
  51   :link '(function-link view-mode)
  52   :link '(custom-manual "(emacs)Misc File Ops")
  53   :group 'wp
  54   :group 'editing)
  55
  56 (defcustom view-highlight-face 'highlight
  57    "*The face used for highlighting the match found by View mode search."
  58    :type 'face
  59    :group 'view)
  60
  61 ;; `view-mode-auto-exit' is replaced by the following option variable which
  62 ;; only says if scrolling past buffer end should leave view mode or not, it
  63 ;; doesn't say if leaving view mode should restore windows or not.  The latter
  64 ;; is now controlled by the presence of a value in `view-return-to-alist'.
  65 (defcustom view-scroll-auto-exit nil
  66   "*Non-nil means scrolling past the end of buffer exits View mode.
  67 A value of nil means attempting to scroll past the end of the buffer,
  68 only rings the bell and gives a message on how to leave."
  69   :type 'boolean
  70   :group 'view)
  71
  72 (defcustom view-try-extend-at-buffer-end nil
  73  "*Non-nil means try to load more of file when reaching end of buffer.
  74 This variable is mainly intended to be temporarily set to non-nil by
  75 the F command in view-mode, but you can set it to t if you want the action
  76 for all scroll commands in view mode."
  77   :type 'boolean
  78   :group 'view)
  79
  80 (defcustom view-remove-frame-by-deleting nil
  81   "*Determine how View mode removes a frame no longer needed.
  82 If nil, make an icon of the frame.  If non-nil, delete the frame."
  83   :type 'boolean
  84   :group 'view)
  85
  86 (defcustom view-exits-all-viewing-windows nil
  87   "*Non-nil means restore all windows used to view buffer.
  88 Commands that restore windows when finished viewing a buffer, apply to all
  89 windows that display the buffer and have restore information in
  90 `view-return-to-alist'.
  91 If `view-exits-all-viewing-windows' is nil, only the selected window is
  92 considered for restoring."
  93   :type 'boolean
  94   :group 'view)
  95
  96 (defcustom view-inhibit-help-message nil
  97   "*Non-nil inhibits the help message shown upon entering View mode."
  98   :type 'boolean
  99   :group 'view
 100   :version "22.1")
 101
 102 ;;;###autoload
 103 (defvar view-mode nil
 104   "Non-nil if View mode is enabled.
 105 Don't change this variable directly, you must change it by one of the
 106 functions that enable or disable view mode.")
 107 ;;;###autoload
 108 (make-variable-buffer-local 'view-mode)
 109
 110 (defcustom view-mode-hook nil
 111   "Normal hook run when starting to view a buffer or file."
 112   :type 'hook
 113   :group 'view)
 114 \f
 115 (defvar view-old-buffer-read-only nil)
 116 (make-variable-buffer-local 'view-old-buffer-read-only)
 117
 118 (defvar view-old-Helper-return-blurb)
 119 (make-variable-buffer-local 'view-old-Helper-return-blurb)
 120
 121 ;; Just to avoid warnings.
 122 (defvar Helper-return-blurb)
 123
 124 (defvar view-page-size nil
 125   "Default number of lines to scroll by View page commands.
 126 If nil that means use the window size.")
 127 (make-variable-buffer-local 'view-page-size)
 128
 129 (defvar view-half-page-size nil
 130   "Default number of lines to scroll by View half page commands.
 131 If nil that means use half the window size.")
 132 (make-variable-buffer-local 'view-half-page-size)
 133
 134 (defvar view-last-regexp nil)
 135 (make-variable-buffer-local 'view-last-regexp) ; Global is better???
 136
 137 (defvar view-return-to-alist nil
 138   "What to do with used windows and where to go when finished viewing buffer.
 139 This is local in each buffer being viewed.
 140 It is added to by `view-mode-enter' when starting to view a buffer and
 141 subtracted from by `view-mode-exit' when finished viewing the buffer.
 142
 143 See RETURN-TO-ALIST argument of function `view-mode-exit' for the format of
 144 `view-return-to-alist'.")
 145 (make-variable-buffer-local 'view-return-to-alist)
 146 (put 'view-return-to-alist 'permanent-local t)
 147
 148 (defvar view-exit-action nil
 149   "nil or a function with one argument (a buffer) called when finished viewing.
 150 This is local in each buffer being viewed.
 151 The \\[view-file] and \\[view-file-other-window] commands may set this to
 152 `kill-buffer'.")
 153 (make-variable-buffer-local 'view-exit-action)
 154
 155 (defvar view-no-disable-on-exit nil
 156   "If non-nil, View mode \"exit\" commands don't actually disable View mode.
 157 Instead, these commands just switch buffers or windows.
 158 This is set in certain buffers by specialized features such as help commands
 159 that use View mode automatically.")
 160
 161 (defvar view-overlay nil
 162   "Overlay used to display where a search operation found its match.
 163 This is local in each buffer, once it is used.")
 164 (make-variable-buffer-local 'view-overlay)
 165
 166 (unless (assq 'view-mode minor-mode-alist)
 167   (setq minor-mode-alist
 168         (cons (list 'view-mode
 169                     (propertize " View"
 170                                 'local-map mode-line-minor-mode-keymap
 171                                 'help-echo "mouse-3: minor mode menu"))
 172               minor-mode-alist)))
 173 \f
 174 ;; Define keymap inside defvar to make it easier to load changes.
 175 ;; Some redundant "less"-like key bindings below have been commented out.
 176 (defvar view-mode-map
 177   (let ((map (make-sparse-keymap)))
 178     (define-key map "C" 'View-kill-and-leave)
 179     (define-key map "c" 'View-leave)
 180     (define-key map "Q" 'View-quit-all)
 181     (define-key map "E" 'View-exit-and-edit)
 182 ;    (define-key map "v" 'View-exit)
 183     (define-key map "e" 'View-exit)
 184     (define-key map "q" 'View-quit)
 185 ;    (define-key map "N" 'View-search-last-regexp-backward)
 186     (define-key map "p" 'View-search-last-regexp-backward)
 187     (define-key map "n" 'View-search-last-regexp-forward)
 188 ;    (define-key map "?" 'View-search-regexp-backward) ; Less does this.
 189     (define-key map "\\" 'View-search-regexp-backward)
 190     (define-key map "/" 'View-search-regexp-forward)
 191     (define-key map "r" 'isearch-backward)
 192     (define-key map "s" 'isearch-forward)
 193     (define-key map "m" 'point-to-register)
 194     (define-key map "'" 'register-to-point)
 195     (define-key map "x" 'exchange-point-and-mark)
 196     (define-key map "@" 'View-back-to-mark)
 197     (define-key map "." 'set-mark-command)
 198     (define-key map "%" 'View-goto-percent)
 199 ;    (define-key map "G" 'View-goto-line-last)
 200     (define-key map "g" 'View-goto-line)
 201     (define-key map "=" 'what-line)
 202     (define-key map "F" 'View-revert-buffer-scroll-page-forward)
 203 ;    (define-key map "k" 'View-scroll-line-backward)
 204     (define-key map "y" 'View-scroll-line-backward)
 205 ;    (define-key map "j" 'View-scroll-line-forward)
 206     (define-key map "\n" 'View-scroll-line-forward)
 207     (define-key map "\r" 'View-scroll-line-forward)
 208     (define-key map "u" 'View-scroll-half-page-backward)
 209     (define-key map "d" 'View-scroll-half-page-forward)
 210     (define-key map "z" 'View-scroll-page-forward-set-page-size)
 211     (define-key map "w" 'View-scroll-page-backward-set-page-size)
 212 ;    (define-key map "b" 'View-scroll-page-backward)
 213     (define-key map "\C-?" 'View-scroll-page-backward)
 214 ;    (define-key map "f" 'View-scroll-page-forward)
 215     (define-key map " " 'View-scroll-page-forward)
 216     (define-key map "o" 'View-scroll-to-buffer-end)
 217     (define-key map ">" 'end-of-buffer)
 218     (define-key map "<" 'beginning-of-buffer)
 219     (define-key map "-" 'negative-argument)
 220     (define-key map "9" 'digit-argument)
 221     (define-key map "8" 'digit-argument)
 222     (define-key map "7" 'digit-argument)
 223     (define-key map "6" 'digit-argument)
 224     (define-key map "5" 'digit-argument)
 225     (define-key map "4" 'digit-argument)
 226     (define-key map "3" 'digit-argument)
 227     (define-key map "2" 'digit-argument)
 228     (define-key map "1" 'digit-argument)
 229     (define-key map "0" 'digit-argument)
 230     (define-key map "H" 'describe-mode)
 231     (define-key map "?" 'describe-mode) ; Maybe do as less instead? See above.
 232     (define-key map "h" 'describe-mode)
 233     map))
 234
 235 (or (assq 'view-mode minor-mode-map-alist)
 236     (setq minor-mode-map-alist
 237           (cons (cons 'view-mode view-mode-map) minor-mode-map-alist)))
 238 \f
 239 ;;; Commands that enter or exit view mode.
 240
 241 ;;;###autoload
 242 (defun view-file (file)
 243   "View FILE in View mode, returning to previous buffer when done.
 244 Emacs commands editing the buffer contents are not available; instead,
 245 a special set of commands (mostly letters and punctuation)
 246 are defined for moving around in the buffer.
 247 Space scrolls forward, Delete scrolls backward.
 248 For list of all View commands, type H or h while viewing.
 249
 250 This command runs the normal hook `view-mode-hook'."
 251   (interactive "fView file: ")
 252   (unless (file-exists-p file) (error "%s does not exist" file))
 253   (let ((had-a-buf (get-file-buffer file))
 254         (buffer (find-file-noselect file)))
 255     (if (eq (with-current-buffer buffer
 256               (get major-mode 'mode-class))
 257             'special)
 258         (progn
 259           (switch-to-buffer buffer)
 260           (message "Not using View mode because the major mode is special"))
 261       (view-buffer buffer (and (not had-a-buf) 'kill-buffer)))))
 262
 263 ;;;###autoload
 264 (defun view-file-other-window (file)
 265   "View FILE in View mode in another window.
 266 Return that window to its previous buffer when done.
 267 Emacs commands editing the buffer contents are not available; instead,
 268 a special set of commands (mostly letters and punctuation)
 269 are defined for moving around in the buffer.
 270 Space scrolls forward, Delete scrolls backward.
 271 For list of all View commands, type H or h while viewing.
 272
 273 This command runs the normal hook `view-mode-hook'."
 274   (interactive "fIn other window view file: ")
 275   (unless (file-exists-p file) (error "%s does not exist" file))
 276   (let ((had-a-buf (get-file-buffer file)))
 277     (view-buffer-other-window (find-file-noselect file) nil
 278                               (and (not had-a-buf) 'kill-buffer))))
 279
 280 ;;;###autoload
 281 (defun view-file-other-frame (file)
 282   "View FILE in View mode in another frame.
 283 Maybe delete other frame and/or return to previous buffer when done.
 284 Emacs commands editing the buffer contents are not available; instead,
 285 a special set of commands (mostly letters and punctuation)
 286 are defined for moving around in the buffer.
 287 Space scrolls forward, Delete scrolls backward.
 288 For list of all View commands, type H or h while viewing.
 289
 290 This command runs the normal hook `view-mode-hook'."
 291   (interactive "fIn other frame view file: ")
 292   (unless (file-exists-p file) (error "%s does not exist" file))
 293   (let ((had-a-buf (get-file-buffer file)))
 294     (view-buffer-other-frame (find-file-noselect file) nil
 295                              (and (not had-a-buf) 'kill-buffer))))
 296
 297
 298 ;;;###autoload
 299 (defun view-buffer (buffer &optional exit-action)
 300   "View BUFFER in View mode, returning to previous buffer when done.
 301 Emacs commands editing the buffer contents are not available; instead,
 302 a special set of commands (mostly letters and punctuation)
 303 are defined for moving around in the buffer.
 304 Space scrolls forward, Delete scrolls backward.
 305 For list of all View commands, type H or h while viewing.
 306
 307 This command runs the normal hook `view-mode-hook'.
 308
 309 Optional argument EXIT-ACTION is either nil or a function with buffer as
 310 argument.  This function is called when finished viewing buffer.
 311 Use this argument instead of explicitly setting `view-exit-action'."
 312
 313   (interactive "bView buffer: ")
 314   (let ((undo-window (list (window-buffer) (window-start) (window-point))))
 315     (switch-to-buffer buffer)
 316     (view-mode-enter (cons (selected-window) (cons nil undo-window))
 317                      exit-action)))
 318
 319 ;;;###autoload
 320 (defun view-buffer-other-window (buffer &optional not-return exit-action)
 321   "View BUFFER in View mode in another window.
 322 Return to previous buffer when done, unless optional NOT-RETURN is non-nil.
 323 Emacs commands editing the buffer contents are not available; instead,
 324 a special set of commands (mostly letters and punctuation)
 325 are defined for moving around in the buffer.
 326 Space scrolls forward, Delete scrolls backward.
 327 For list of all View commands, type H or h while viewing.
 328
 329 This command runs the normal hook `view-mode-hook'.
 330
 331 Optional argument EXIT-ACTION is either nil or a function with buffer as
 332 argument.  This function is called when finished viewing buffer.
 333 Use this argument instead of explicitly setting `view-exit-action'."
 334   (interactive "bIn other window view buffer:\nP")
 335   (let* ((win                           ; This window will be selected by
 336           (get-lru-window))             ; switch-to-buffer-other-window below.
 337          (return-to
 338           (and (not not-return)
 339                (cons (selected-window)
 340                      (if (eq win (selected-window))
 341                          t                      ; Has to make new window.
 342                        (list
 343                         (window-buffer win)     ; Other windows old buffer.
 344                         (window-start win)
 345                         (window-point win)))))))
 346     (switch-to-buffer-other-window buffer)
 347     (view-mode-enter (and return-to (cons (selected-window) return-to))
 348                      exit-action)))
 349
 350 ;;;###autoload
 351 (defun view-buffer-other-frame (buffer &optional not-return exit-action)
 352   "View BUFFER in View mode in another frame.
 353 Return to previous buffer when done, unless optional NOT-RETURN is non-nil.
 354 Emacs commands editing the buffer contents are not available; instead,
 355 a special set of commands (mostly letters and punctuation)
 356 are defined for moving around in the buffer.
 357 Space scrolls forward, Delete scrolls backward.
 358 For list of all View commands, type H or h while viewing.
 359
 360 This command runs the normal hook `view-mode-hook'.
 361
 362 Optional argument EXIT-ACTION is either nil or a function with buffer as
 363 argument.  This function is called when finished viewing buffer.
 364 Use this argument instead of explicitly setting `view-exit-action'."
 365   (interactive "bView buffer in other frame: \nP")
 366   (let ((return-to
 367          (and (not not-return) (cons (selected-window) t)))) ; Old window.
 368     (switch-to-buffer-other-frame buffer)
 369     (view-mode-enter (and return-to (cons (selected-window) return-to))
 370                      exit-action)))
 371 \f
 372 ;;;###autoload
 373 (defun view-mode (&optional arg)
 374   ;; In the following documentation string we have to use some explicit key
 375   ;; bindings instead of using the \\[] construction.  The reason for this
 376   ;; is that most commands have more than one key binding.
 377   "Toggle View mode, a minor mode for viewing text but not editing it.
 378 With prefix argument ARG, turn View mode on if ARG is positive, otherwise
 379 turn it off.
 380
 381 Emacs commands that do not change the buffer contents are available as usual.
 382 Kill commands insert text in kill buffers but do not delete.  Other commands
 383 \(among them most letters and punctuation) beep and tell that the buffer is
 384 read-only.
 385 \\<view-mode-map>
 386 The following additional commands are provided.  Most commands take prefix
 387 arguments.  Page commands default to \"page size\" lines which is almost a whole
 388 window full, or number of lines set by \\[View-scroll-page-forward-set-page-size] or \\[View-scroll-page-backward-set-page-size].  Half page commands default to
 389 and set \"half page size\" lines which initially is half a window full.  Search
 390 commands default to a repeat count of one.
 391
 392 H, h, ?  This message.
 393 Digits  provide prefix arguments.
 394 \\[negative-argument]   negative prefix argument.
 395 \\[beginning-of-buffer] move to the beginning of buffer.
 396 >       move to the end of buffer.
 397 \\[View-scroll-to-buffer-end]   scroll so that buffer end is at last line of window.
 398 SPC     scroll forward \"page size\" lines.
 399           With prefix scroll forward prefix lines.
 400 DEL     scroll backward \"page size\" lines.
 401           With prefix scroll backward prefix lines.
 402 \\[View-scroll-page-forward-set-page-size]      like  \\[View-scroll-page-forward]  but with prefix sets \"page size\" to prefix.
 403 \\[View-scroll-page-backward-set-page-size]     like  \\[View-scroll-page-backward]  but with prefix sets \"page size\" to prefix.
 404 \\[View-scroll-half-page-forward]       scroll forward \"half page size\" lines.  With prefix, sets
 405           \"half page size\" to prefix lines and scrolls forward that much.
 406 \\[View-scroll-half-page-backward]      scroll backward \"half page size\" lines.  With prefix, sets
 407           \"half page size\" to prefix lines and scrolls backward that much.
 408 RET, LFD  scroll forward one line.  With prefix scroll forward prefix line(s).
 409 y       scroll backward one line.  With prefix scroll backward prefix line(s).
 410 \\[View-revert-buffer-scroll-page-forward]      revert-buffer if necessary and scroll forward.
 411           Use this to view a changing file.
 412 \\[what-line]   prints the current line number.
 413 \\[View-goto-percent]   goes prefix argument (default 100) percent into buffer.
 414 \\[View-goto-line]      goes to line given by prefix argument (default first line).
 415 .       set the mark.
 416 x       exchanges point and mark.
 417 \\[View-back-to-mark]   return to mark and pops mark ring.
 418           Mark ring is pushed at start of every successful search and when
 419           jump to line occurs.  The mark is set on jump to buffer start or end.
 420 \\[point-to-register]   save current position in character register.
 421 '       go to position saved in character register.
 422 s       do forward incremental search.
 423 r       do reverse incremental search.
 424 \\[View-search-regexp-forward]  searches forward for regular expression, starting after current page.
 425           ! and @ have a special meaning at the beginning of the regexp.
 426           ! means search for a line with no match for regexp.  @ means start
 427           search at beginning (end for backward search) of buffer.
 428 \\      searches backward for regular expression, starting before current page.
 429 \\[View-search-last-regexp-forward]     searches forward for last regular expression.
 430 p       searches backward for last regular expression.
 431 \\[View-quit]   quit View mode, restoring this window and buffer to previous state.
 432           \\[View-quit] is the normal way to leave view mode.
 433 \\[View-exit]   exit View mode but stay in current buffer.  Use this if you started
 434           viewing a buffer (file) and find out you want to edit it.
 435           This command restores the previous read-only status of the buffer.
 436 \\[View-exit-and-edit]  exit View mode, and make the current buffer editable
 437           even if it was not editable before entry to View mode.
 438 \\[View-quit-all]       quit View mode, restoring all windows to previous state.
 439 \\[View-leave]  quit View mode and maybe switch buffers, but don't kill this buffer.
 440 \\[View-kill-and-leave] quit View mode, kill current buffer and go back to other buffer.
 441
 442 The effect of \\[View-leave], \\[View-quit] and \\[View-kill-and-leave] depends on how view-mode was entered.  If it was
 443 entered by view-file, view-file-other-window, view-file-other-frame, or
 444 \\[dired-view-file] \(\\[view-file], \\[view-file-other-window],
 445 \\[view-file-other-frame], or the Dired mode v command),
 446 then \\[View-quit] will try to kill the current buffer.
 447 If view-mode was entered from another buffer, by \\[view-buffer],
 448 \\[view-buffer-other-window], \\[view-buffer-other frame], \\[view-file],
 449 \\[view-file-other-window], or \\[view-file-other-frame],
 450 then \\[View-leave], \\[View-quit] and \\[View-kill-and-leave] will return to that buffer.
 451
 452 Entry to view-mode runs the normal hook `view-mode-hook'."
 453   (interactive "P")
 454   (unless (and arg                      ; Do nothing if already OK.
 455                (if (> (prefix-numeric-value arg) 0) view-mode (not view-mode)))
 456     (if view-mode (view-mode-disable)
 457       (view-mode-enable))))
 458 \f
 459 (defun view-mode-enable ()
 460   "Turn on View mode."
 461   ;; Always leave view mode before changing major mode.
 462   ;; This is to guarantee that the buffer-read-only variable is restored.
 463   (add-hook 'change-major-mode-hook 'view-mode-disable nil t)
 464   (setq view-mode t
 465         view-page-size nil
 466         view-half-page-size nil
 467         view-old-buffer-read-only buffer-read-only
 468         buffer-read-only t
 469         view-old-Helper-return-blurb (and (boundp 'Helper-return-blurb)
 470                                           Helper-return-blurb)
 471         Helper-return-blurb
 472         (format "continue viewing %s"
 473                 (if (buffer-file-name)
 474                     (file-name-nondirectory (buffer-file-name))
 475                   (buffer-name))))
 476   (force-mode-line-update)
 477   (run-hooks 'view-mode-hook))
 478
 479 (defun view-mode-disable ()
 480   "Turn off View mode."
 481   (remove-hook 'change-major-mode-hook 'view-mode-disable t)
 482   (and view-overlay (delete-overlay view-overlay))
 483   (force-mode-line-update)
 484   ;; Calling toggle-read-only while View mode is enabled
 485   ;; sets view-read-only to t as a buffer-local variable
 486   ;; after exiting View mode.  That arranges that the next toggle-read-only
 487   ;; will reenable View mode.
 488   ;; Cancelling View mode in any other way should cancel that, too,
 489   ;; so that View mode stays off if toggle-read-only is called.
 490   (if (local-variable-p 'view-read-only)
 491       (kill-local-variable 'view-read-only))
 492   (setq view-mode nil
 493         Helper-return-blurb view-old-Helper-return-blurb)
 494   (if buffer-read-only
 495       (setq buffer-read-only view-old-buffer-read-only)))
 496
 497 ;;;###autoload
 498 (defun view-mode-enter (&optional return-to exit-action) "\
 499 Enter View mode and set up exit from view mode depending on optional arguments.
 500 If RETURN-TO is non-nil it is added as an element to the buffer local alist
 501 `view-return-to-alist'.
 502 Save EXIT-ACTION in buffer local variable `view-exit-action'.
 503 It should be either nil or a function that takes a buffer as argument.
 504 This function will be called by `view-mode-exit'.
 505
 506 RETURN-TO is either nil, meaning do nothing when exiting view mode, or
 507 it has the format (WINDOW OLD-WINDOW . OLD-BUF-INFO).
 508 WINDOW is a window used for viewing.
 509 OLD-WINDOW is nil or the window to select after viewing.
 510 OLD-BUF-INFO tells what to do with WINDOW when exiting.  It is one of:
 511 1) nil       Do nothing.
 512 2) t         Delete WINDOW or, if it is the only window, its frame.
 513 3) (OLD-BUFF START POINT)  Display buffer OLD-BUFF with displayed text
 514                            starting at START and point at POINT in WINDOW.
 515 4) quit-window   Do `quit-window' in WINDOW.
 516
 517 For list of all View commands, type H or h while viewing.
 518
 519 This function runs the normal hook `view-mode-hook'."
 520   (if return-to
 521       (let ((entry (assq (car return-to) view-return-to-alist)))
 522         (if entry (setcdr entry (cdr return-to))
 523           (setq view-return-to-alist (cons return-to view-return-to-alist)))))
 524   (if exit-action (setq view-exit-action exit-action))
 525   (unless view-mode                     ; Do nothing if already in view mode.
 526     (view-mode-enable)
 527     (force-mode-line-update)
 528     (unless view-inhibit-help-message
 529       (message "%s"
 530                (substitute-command-keys "\
 531 View mode: type \\[help-command] for help, \\[describe-mode] for commands, \\[View-quit] to quit.")))))
 532 \f
 533 (defun view-mode-exit (&optional return-to-alist exit-action all-win)
 534   "Exit View mode in various ways, depending on optional arguments.
 535 RETURN-TO-ALIST, EXIT-ACTION and ALL-WIN determine what to do after exit.
 536 EXIT-ACTION is nil or a function that is called with current buffer as
 537 argument.
 538 RETURN-TO-ALIST is an alist that for some of the windows displaying the
 539 current buffer, associate information on what to do with those windows.
 540 If ALL-WIN or the variable `view-exits-all-viewing-windows' is non-nil,
 541 then all windows on RETURN-TO-ALIST are restored to their old state.
 542 Otherwise only the selected window is affected (if it is on RETURN-TO-ALIST).
 543
 544 Elements of RETURN-TO-ALIST have the format (WINDOW OLD-WINDOW . OLD-BUF-INFO).
 545 WINDOW is a window displaying the current buffer.
 546 OLD-WINDOW is nil or a window to select after viewing.
 547 OLD-BUF-INFO is information on what to do with WINDOW and is one of:
 548 1) nil       Do nothing.
 549 2) t         Delete WINDOW and, if it is the only window, its frame.
 550 3) (OLD-BUF START POINT)  Display buffer OLD-BUF with displayed text
 551                           starting at START and point at POINT in WINDOW.
 552 4) quit-window   Do `quit-window' in WINDOW.
 553
 554 If one of the WINDOW in RETURN-TO-ALIST is the selected window and the
 555 corresponding OLD-WINDOW is a live window, then select OLD-WINDOW."
 556   (setq all-win
 557         (and return-to-alist (or all-win view-exits-all-viewing-windows)))
 558   (if view-mode         ; Only do something if in view mode.
 559       (let* ((buffer (current-buffer))
 560              window notlost
 561              (sel-old (assq (selected-window) return-to-alist))
 562              (alist (cond
 563                      (all-win           ; Try to restore all windows.
 564                       (append return-to-alist nil)) ; Copy.
 565                      (sel-old           ; Only selected window.
 566                       (list sel-old))))
 567              (old-window (if sel-old (car (cdr sel-old)))))
 568         (if all-win                     ; Follow chains of old-windows.
 569             (let ((c (length alist)) a)
 570               (while (and (> c 0)       ; Safety if mutually refering windows.
 571                           (or (not (window-live-p old-window))
 572                               (eq buffer (window-buffer old-window)))
 573                           (setq a (assq old-window alist)))
 574                 (setq c (1- c))
 575                 (setq old-window (car (cdr a))))
 576               (if (or (zerop c) (not (window-live-p old-window)))
 577                   (setq old-window (selected-window)))))
 578         (or view-no-disable-on-exit
 579             (view-mode-disable))
 580         (while alist                    ; Restore windows with info.
 581           (setq notlost nil)
 582           (if (and (window-live-p (setq window (car (car alist))))
 583                    (eq buffer (window-buffer window)))
 584               (let ((frame (window-frame window))
 585                     (old-buf-info (cdr (cdr (car alist)))))
 586                 (if all-win (select-window window))
 587                 (cond
 588                  ((and (consp old-buf-info) ; Case 3.
 589                        (buffer-live-p (car old-buf-info)))
 590                   (set-window-buffer window (car old-buf-info)) ; old-buf
 591                   (set-window-start window (car (cdr old-buf-info)))
 592                   (set-window-point window (car (cdr (cdr old-buf-info)))))
 593                  ((eq old-buf-info 'quit-window)
 594                   (quit-window))        ; Case 4.
 595                  ((not (eq old-buf-info t)) nil) ; Not case 2, do nothing.
 596                  ((not (one-window-p t)) (delete-window))
 597                  ((not (eq frame (next-frame)))
 598                   ;; Not the only frame, so can safely be removed.
 599                   (if view-remove-frame-by-deleting
 600                       (delete-frame frame)
 601                     (setq notlost t)    ; Keep the window. See below.
 602                     (iconify-frame frame))))))
 603           ;; If a frame is removed by iconifying it, then the window is not
 604           ;; really lost.  In this case we keep the entry in
 605           ;; view-return-to-alist so that if the user deiconifies the frame
 606           ;; and then press q, then the frame is iconified again.
 607           (unless notlost
 608             (setq view-return-to-alist
 609                   (delete (car alist) view-return-to-alist)))
 610           (setq alist (cdr alist)))
 611         (if (window-live-p old-window)  ; still existing window
 612             (select-window old-window))
 613         (when exit-action
 614           (setq view-exit-action nil)
 615           (funcall exit-action buffer))
 616         (force-mode-line-update))))
 617 \f
 618 (defun View-exit ()
 619   "Exit View mode but stay in current buffer."
 620   (interactive)
 621   (view-mode-exit))
 622
 623 ;;;###autoload
 624 (defun View-exit-and-edit ()
 625   "Exit View mode and make the current buffer editable."
 626   (interactive)
 627   (let ((view-old-buffer-read-only nil)
 628         (view-no-disable-on-exit nil))
 629     (view-mode-exit)))
 630
 631 (defun View-leave ()
 632   "Quit View mode and maybe switch buffers, but don't kill this buffer."
 633   (interactive)
 634   (view-mode-exit view-return-to-alist))
 635
 636 (defun View-quit ()
 637   "Quit View mode, trying to restore window and buffer to previous state.
 638 Maybe kill this buffer.  Try to restore selected window to previous state
 639 and go to previous buffer or window."
 640   (interactive)
 641   (view-mode-exit view-return-to-alist view-exit-action))
 642
 643 (defun View-quit-all ()
 644   "Quit View mode, trying to restore windows and buffers to previous state.
 645 Maybe kill current buffer.  Try to restore all windows viewing buffer to
 646 previous state and go to previous buffer or window."
 647   (interactive)
 648   (view-mode-exit view-return-to-alist view-exit-action t))
 649
 650 (defun View-kill-and-leave ()
 651   "Quit View mode, kill current buffer and return to previous buffer."
 652   (interactive)
 653   (view-mode-exit view-return-to-alist (or view-exit-action 'kill-buffer) t))
 654 \f
 655
 656 ;;; Some help routines.
 657
 658 (defun view-window-size ()
 659   ;; Window height excluding mode line.
 660   (1- (window-height)))
 661
 662 ;(defun view-last-command (&optional who what)
 663 ;  (setq view-last-command-entry this-command)
 664 ;  (setq view-last-command who)
 665 ;  (setq view-last-command-argument what))
 666
 667 ;(defun View-repeat-last-command ()
 668 ;  "Repeat last command issued in View mode."
 669 ;  (interactive)
 670 ;  (if (and view-last-command
 671 ;          (eq view-last-command-entry last-command))
 672 ;      (funcall view-last-command view-last-command-argument))
 673 ;  (setq this-command view-last-command-entry))
 674
 675 (defun view-recenter ()
 676   ;; Center point in window.
 677   (recenter (/ (view-window-size) 2)))
 678
 679 (defun view-page-size-default (lines)
 680   ;; Get page size.
 681   (let ((default (- (view-window-size) next-screen-context-lines)))
 682     (if (or (null lines) (zerop (setq lines (prefix-numeric-value lines))))
 683         default
 684       (min (abs lines) default))))
 685
 686 (defun view-set-half-page-size-default (lines)
 687   ;; Get and maybe set half page size.
 688   (if (not lines) (or view-half-page-size
 689                       (/ (view-window-size) 2))
 690     (setq view-half-page-size
 691           (if (zerop (setq lines (prefix-numeric-value lines)))
 692               (/ (view-window-size) 2)
 693             (view-page-size-default lines)))))
 694
 695
 696 ;;; Commands for moving around in the buffer.
 697
 698 (defun View-goto-percent (&optional percent)
 699   "Move to end (or prefix PERCENT) of buffer in View mode.
 700 Display is centered at point.
 701 Also set the mark at the position where point was."
 702   (interactive "P")
 703   (push-mark)
 704   (goto-char
 705    (if percent
 706        (+ (point-min)
 707           (floor (* (- (point-max) (point-min)) 0.01
 708                     (max 0 (min 100 (prefix-numeric-value percent))))))
 709      (point-max)))
 710   (view-recenter))
 711
 712 ;(defun View-goto-line-last (&optional line)
 713 ;"Move to last (or prefix LINE) line in View mode.
 714 ;Display is centered at LINE.
 715 ;Sets mark at starting position and pushes mark ring."
 716 ;  (interactive "P")
 717 ;  (push-mark)
 718 ;  (if line (goto-line (prefix-numeric-value line))
 719 ;    (goto-char (point-max))
 720 ;    (beginning-of-line))
 721 ;  (view-recenter))
 722
 723 (defun View-goto-line (&optional line)
 724   "Move to first (or prefix LINE) line in View mode.
 725 Display is centered at LINE.
 726 Also set the mark at the position where point was."
 727   (interactive "p")
 728   (push-mark)
 729   (goto-line line)
 730   (view-recenter))
 731
 732 (defun View-back-to-mark (&optional ignore)
 733   "Return to last mark set in View mode, else beginning of file.
 734 Display that line at the center of the window.
 735 This command pops the mark ring, so that successive
 736 invocations return to earlier marks."
 737   (interactive)
 738   (goto-char (or (mark t) (point-min)))
 739   (pop-mark)
 740   (view-recenter))
 741 \f
 742 (defun view-scroll-lines (lines backward default maxdefault)
 743   ;; This function does the job for all the scrolling commands.
 744   ;; Scroll forward LINES lines.  If BACKWARD is true scroll backwards.
 745   ;; If LINES is negative scroll in the other direction.  If LINES is 0 or nil,
 746   ;; scroll DEFAULT lines.  If MAXDEFAULT is true then scroll no more than a
 747   ;; window full.
 748   (if (or (null lines) (zerop (setq lines (prefix-numeric-value lines))))
 749       (setq lines default))
 750   (when (< lines 0)
 751     (setq backward (not backward)) (setq lines (- lines)))
 752   (setq default (view-page-size-default nil)) ; Max scrolled at a time.
 753   (if maxdefault (setq lines (min lines default)))
 754   (cond
 755    (backward (scroll-down lines))
 756    ((view-really-at-end)
 757     (if view-scroll-auto-exit (View-quit)
 758       (ding)
 759       (view-end-message)))
 760    (t (while (> lines default)
 761         (scroll-up default)
 762         (setq lines (- lines default))
 763         (if (view-really-at-end) (setq lines 0)))
 764       (scroll-up lines)
 765       (if (view-really-at-end) (view-end-message))
 766       (move-to-window-line -1)
 767       (beginning-of-line))))
 768
 769 (defun view-really-at-end ()
 770   ;; Return true if buffer end visible.  Maybe revert buffer and test.
 771   (and (pos-visible-in-window-p (point-max))
 772        (let ((buf (current-buffer))
 773              (bufname (buffer-name))
 774              (file (buffer-file-name)))
 775          (or (not view-try-extend-at-buffer-end)
 776              (null file)
 777              (verify-visited-file-modtime buf)
 778              (not (file-exists-p file))
 779              (when (buffer-modified-p buf)
 780                (setq file (file-name-nondirectory file))
 781                (not (yes-or-no-p
 782                      (format
 783                       "File %s changed on disk.  Discard your edits%s? "
 784                       file
 785                       (if (string= bufname file) ""
 786                         (concat " in " bufname))))))
 787              (progn
 788                (revert-buffer t t t)
 789                (pos-visible-in-window-p (point-max)))))))
 790
 791 (defun view-end-message ()
 792   ;; Tell that we are at end of buffer.
 793   (goto-char (point-max))
 794   (if view-return-to-alist
 795       (message "End of buffer.  Type %s to quit viewing."
 796                (substitute-command-keys
 797                 (if view-scroll-auto-exit "\\[View-scroll-page-forward]"
 798                   "\\[View-quit]")))
 799     (message "End of buffer")))
 800 \f
 801 (defun View-scroll-to-buffer-end ()
 802   "Scroll backward or forward so that buffer end is at last line of window."
 803   (interactive)
 804   (let ((p (if (pos-visible-in-window-p (point-max)) (point))))
 805     (goto-char (point-max))
 806     (recenter -1)
 807     (and p (goto-char p))))
 808
 809 (defun View-scroll-page-forward (&optional lines)
 810   "Scroll \"page size\" or prefix LINES lines forward in View mode.
 811 Exit if end of text is visible and `view-scroll-auto-exit' is non-nil.
 812 \"page size\" is whole window full, or number of lines set by
 813 \\[View-scroll-page-forward-set-page-size] or
 814 \\[View-scroll-page-backward-set-page-size].
 815 If LINES is more than a window-full, only the last window-full is shown."
 816   (interactive "P")
 817   (view-scroll-lines lines nil (view-page-size-default view-page-size) nil))
 818
 819 (defun View-scroll-page-backward (&optional lines)
 820   "Scroll \"page size\" or prefix LINES lines backward in View mode.
 821 See also `View-scroll-page-forward'."
 822   (interactive "P")
 823   (view-scroll-lines lines t (view-page-size-default view-page-size) nil))
 824
 825 (defun View-scroll-page-forward-set-page-size (&optional lines)
 826   "Scroll forward LINES lines in View mode, setting the \"page size\".
 827 This is the number of lines which \\[View-scroll-page-forward] and
 828 \\[View-scroll-page-backward] scroll by default.
 829 If LINES is omitted or = 0, sets \"page size\" to window height and
 830 scrolls forward that much, otherwise scrolls forward LINES lines and sets
 831 \"page size\" to the minimum of window height and the absolute value of LINES.
 832 See also `View-scroll-page-forward'."
 833   (interactive "P")
 834   (view-scroll-lines lines nil
 835                      (setq view-page-size (view-page-size-default lines))
 836                      nil))
 837
 838 (defun View-scroll-page-backward-set-page-size (&optional lines)
 839   "Scroll backward prefix LINES lines in View mode, setting the \"page size\".
 840 See also `View-scroll-page-forward-set-page-size'."
 841   (interactive "P")
 842   (view-scroll-lines lines t
 843                      (setq view-page-size (view-page-size-default lines))
 844                      nil))
 845
 846 (defun View-scroll-line-forward (&optional lines)
 847   "Scroll forward one line (or prefix LINES lines) in View mode.
 848 See also `View-scroll-page-forward,' but note that scrolling is limited
 849 to minimum of LINES and one window-full."
 850   (interactive "P")
 851   (view-scroll-lines lines nil 1 t))
 852
 853 (defun View-scroll-line-backward (&optional lines)
 854   "Scroll backward one line (or prefix LINES lines) in View mode.
 855 See also `View-scroll-line-forward'."
 856   (interactive "P")
 857   (view-scroll-lines lines t 1 t))
 858
 859 (defun View-scroll-half-page-forward (&optional lines)
 860   "Scroll forward a \"half page\" (or prefix LINES) lines in View mode.
 861 If LINES is not omitted, the \"half page size\" is set to the minimum of
 862 window height and the absolute value of LINES.
 863 LINES=0 resets \"half page size\" to half window height."
 864   (interactive "P")
 865   (view-scroll-lines lines nil (view-set-half-page-size-default lines) t))
 866
 867 (defun View-scroll-half-page-backward (&optional lines)
 868   "Scroll backward a \"half page\" (or prefix LINES) lines in View mode.
 869 See also `View-scroll-half-page-forward'."
 870   (interactive "P")
 871   (view-scroll-lines lines t (view-set-half-page-size-default lines) t))
 872
 873 (defun View-revert-buffer-scroll-page-forward (&optional lines)
 874   "Scroll forward, reverting buffer if needed, in View mode.
 875 If buffer has not been changed and the corresponding file is newer, first
 876 revert the buffer, then scroll.
 877 This command is useful if you are viewing a changing file.
 878
 879 The prefix argument LINES says how many lines to scroll.
 880 If you don't specify a prefix argument, it uses the number of lines set by
 881 \\[View-scroll-page-forward-set-page-size] or
 882 \\[View-scroll-page-backward-set-page-size].
 883 If LINES is more than a window-full, only the last window-full is shown."
 884   (interactive "P")
 885   (let ((view-scroll-auto-exit nil)
 886         (view-try-extend-at-buffer-end t))
 887     (view-scroll-lines lines nil (view-page-size-default view-page-size) nil)))
 888 \f
 889 (defun View-search-regexp-forward (n regexp)
 890   "Search forward for first (or prefix Nth) occurrence of REGEXP in View mode.
 891
 892 Displays line found at center of window.  Sets mark at starting position and
 893 pushes mark ring.
 894
 895 Characters @ and ! are special at the beginning of REGEXP.  They modify
 896 the search rather than become part of the pattern searched for.
 897 @ means search all the buffer i.e. start search at the beginning of buffer.
 898 ! means search for a line that contains no match for the pattern.
 899 If REGEXP is empty or only consist of these control characters, then
 900 an earlier remembered REGEXP is used, otherwise REGEXP is remembered
 901 for use by later search commands.
 902
 903 The variable `view-highlight-face' controls the face that is used
 904 for highlighting the match that is found."
 905   (interactive "p\nsSearch forward (regexp): ")
 906   (view-search n regexp))
 907
 908 (defun View-search-regexp-backward (n regexp)
 909   "Search backward for first (or prefix Nth) occurrence of REGEXP in View mode.
 910
 911 Displays line found at center of window.  Sets mark at starting position and
 912 pushes mark ring.
 913
 914 Characters @ and ! are special at the beginning of REGEXP.  They modify
 915 the search rather than become part of the pattern searched for.
 916 @ means search all the buffer i.e. start search at the end of buffer.
 917 ! means search for a line that contains no match for the pattern.
 918 If REGEXP is empty or only consist of these control characters, then
 919 an earlier remembered REGEXP is used, otherwise REGEXP is remembered
 920 for use by later search commands.
 921
 922 The variable `view-highlight-face' controls the face that is used
 923 for highlighting the match that is found."
 924   (interactive "p\nsSearch backward (regexp): ")
 925   (view-search (- n) regexp))
 926
 927 (defun View-search-last-regexp-forward (n) "\
 928 Search forward for first (or prefix Nth) instance of last regexp in View mode.
 929 Displays line found at center of window.  Sets mark at starting position and
 930 pushes mark ring.
 931
 932 The variable `view-highlight-face' controls the face that is used
 933 for highlighting the match that is found."
 934   (interactive "p")
 935   (view-search n nil))
 936
 937 (defun View-search-last-regexp-backward (n) "\
 938 Search backward for first (or prefix Nth) instance of last regexp in View mode.
 939 Displays line found at center of window.  Sets mark at starting position and
 940 pushes mark ring.
 941
 942 The variable `view-highlight-face' controls the face that is used
 943 for highlighting the match that is found."
 944   (interactive "p")
 945   (view-search (- n) nil))
 946
 947 (defun view-search (times regexp)
 948   ;; This function does the job for all the View-search- commands.
 949   ;; Search for the TIMESt match for REGEXP. If TIMES is negative
 950   ;; search backwards. If REGEXP is nil use `view-last-regexp'.
 951   ;; Charcters "!" and "@" have a special meaning at the beginning of
 952   ;; REGEXP and are removed from REGEXP before the search "!" means
 953   ;; search for lines with no match for REGEXP.  "@" means search in
 954   ;; the whole buffer, don't start searching from the present point.
 955   (let (where no end ln)
 956     (cond
 957      ((and regexp (> (length regexp) 0)
 958            (or (not (memq (string-to-char regexp) '(?! ?@)))
 959                (progn
 960                  (if (member (substring regexp 0 2) '("!@" "@!"))
 961                      (setq end t no t ln 2)
 962                    (setq no (not (setq end (eq ?@ (string-to-char regexp))))
 963                          ln 1))
 964                  (> (length (setq regexp (substring regexp ln))) 0))))
 965       (setq view-last-regexp (if no (list regexp) regexp)))
 966      ((consp view-last-regexp)
 967       (setq regexp (car view-last-regexp))
 968       (unless (setq no (not no)) (setq view-last-regexp regexp)))
 969      (view-last-regexp (setq regexp view-last-regexp)
 970                        (if no (setq view-last-regexp (list regexp))))
 971      (t (error "No previous View-mode search")))
 972     (save-excursion
 973       (if end (goto-char (if (< times 0) (point-max) (point-min)))
 974         (move-to-window-line (if (< times 0) 0 -1)))
 975       (if (if no (view-search-no-match-lines times regexp)
 976             (re-search-forward regexp nil t times))
 977           (setq where (point))))
 978     (if where
 979         (progn
 980           (push-mark)
 981           (goto-char where)
 982           (if view-overlay
 983               (move-overlay view-overlay (match-beginning 0) (match-end 0))
 984             (setq view-overlay
 985                   (make-overlay (match-beginning 0) (match-end 0))))
 986           (overlay-put view-overlay 'face view-highlight-face)
 987           (beginning-of-line)
 988           (view-recenter))
 989       (message "Can't find occurrence %d of %s%s"
 990                times (if no "no " "") regexp)
 991       (sit-for 4))))
 992
 993 ;; This is the dumb approach, looking at each line.  The original
 994 ;; version of this function looked like it might have been trying to
 995 ;; do something clever, but not succeeding:
 996 ;; http://lists.gnu.org/archive/html/bug-gnu-emacs/2007-09/msg00073.html
 997 (defun view-search-no-match-lines (times regexp)
 998   "Search for the TIMESth occurrence of a line with no match for REGEXP.
 999 If such a line is found, return non-nil and set the match-data to that line.
1000 If TIMES is negative, search backwards."
1001   (let ((step (if (>= times 0) 1
1002                 (setq times (- times))
1003                 -1)))
1004     ;; Note that we do not check the current line.
1005     (while (and (> times 0)
1006                 (zerop (forward-line step)))
1007       ;; (forward-line 1) returns 0 on moving within the last line.
1008       (if (eobp)
1009           (setq times -1)
1010         (or (re-search-forward regexp (line-end-position) t)
1011             (setq times (1- times))))))
1012   (and (zerop times)
1013        (looking-at ".*")))
1014
1015 (provide 'view)
1016
1017 ;;; arch-tag: 6d0ace36-1d12-4de3-8de3-1fa3231636d7
1018 ;;; view.el ends here