lisp/view.el

   1 ;;; view.el --- peruse file or buffer without editing
   2
   3 ;; Copyright (C) 1985, 1989, 1994-1995, 1997, 2000-2015 Free Software
   4 ;; 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 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 ;; This package provides the `view' minor mode documented in the Emacs
  28 ;; user's manual.
  29 ;; View mode entry and exit is done through the functions view-mode-enter
  30 ;; and view-mode-exit.  Use these functions to enter or exit view-mode from
  31 ;; emacs lisp programs.
  32 ;; We use both view- and View- as prefix for symbols.  View- is used as
  33 ;; prefix for commands that have a key binding.  view- is used for commands
  34 ;; without key binding.  The purpose of this is to make it easier for a
  35 ;; user to use command name completion.
  36
  37 ;;; Suggested key bindings:
  38 ;;
  39 ;; (define-key ctl-x-4-map "v" 'view-file-other-window)  ; ^x4v
  40 ;; (define-key ctl-x-5-map "v" 'view-file-other-frame)  ; ^x5v
  41 ;;
  42 ;; You could also bind view-file, view-buffer, view-buffer-other-window and
  43 ;; view-buffer-other-frame to keys.
  44 \f
  45 ;;; Code:
  46
  47 (defgroup view nil
  48   "Peruse file or buffer without editing."
  49   :link '(function-link view-mode)
  50   :link '(custom-manual "(emacs)Misc File Ops")
  51   :group 'wp)
  52
  53 (defcustom view-highlight-face 'highlight
  54    "The face used for highlighting the match found by View mode search."
  55    :type 'face
  56    :group 'view)
  57
  58 (defcustom view-scroll-auto-exit nil
  59   "Non-nil means scrolling past the end of buffer exits View mode.
  60 A value of nil means attempting to scroll past the end of the buffer,
  61 only rings the bell and gives a message on how to leave."
  62   :type 'boolean
  63   :group 'view)
  64
  65 (defcustom view-try-extend-at-buffer-end nil
  66  "Non-nil means try to load more of file when reaching end of buffer.
  67 This variable is mainly intended to be temporarily set to non-nil by
  68 the F command in view-mode, but you can set it to t if you want the action
  69 for all scroll commands in view mode."
  70   :type 'boolean
  71   :group 'view)
  72
  73 ;;;###autoload
  74 (defcustom view-remove-frame-by-deleting t
  75   "Determine how View mode removes a frame no longer needed.
  76 If nil, make an icon of the frame.  If non-nil, delete the frame."
  77   :type 'boolean
  78   :group 'view
  79   :version "23.1")
  80
  81 (defcustom view-exits-all-viewing-windows nil
  82   "Non-nil means restore all windows used to view buffer.
  83 Commands that restore windows when finished viewing a buffer,
  84 apply to all windows that display the buffer and have restore
  85 information.  If `view-exits-all-viewing-windows' is nil, only
  86 the selected window is considered for restoring."
  87   :type 'boolean
  88   :group 'view)
  89
  90 (defcustom view-inhibit-help-message nil
  91   "Non-nil inhibits the help message shown upon entering View mode."
  92   :type 'boolean
  93   :group 'view
  94   :version "22.1")
  95
  96 ;;;###autoload
  97 (defvar view-mode nil
  98   "Non-nil if View mode is enabled.
  99 Don't change this variable directly, you must change it by one of the
 100 functions that enable or disable view mode.")
 101 ;;;###autoload
 102 (make-variable-buffer-local 'view-mode)
 103
 104 (defcustom view-mode-hook nil
 105   "Normal hook run when starting to view a buffer or file."
 106   :type 'hook
 107   :group 'view)
 108 \f
 109 (defvar view-old-buffer-read-only nil)
 110 (make-variable-buffer-local 'view-old-buffer-read-only)
 111
 112 (defvar view-old-Helper-return-blurb)
 113 (make-variable-buffer-local 'view-old-Helper-return-blurb)
 114
 115 (defvar view-page-size nil
 116   "Default number of lines to scroll by View page commands.
 117 If nil that means use the window size.")
 118 (make-variable-buffer-local 'view-page-size)
 119
 120 (defvar view-half-page-size nil
 121   "Default number of lines to scroll by View half page commands.
 122 If nil that means use half the window size.")
 123 (make-variable-buffer-local 'view-half-page-size)
 124
 125 (defvar view-last-regexp nil)
 126 (make-variable-buffer-local 'view-last-regexp) ; Global is better???
 127
 128 (defvar view-return-to-alist nil
 129   "What to do with used windows and where to go when finished viewing buffer.
 130 This is local in each buffer being viewed.
 131 It is added to by `view-mode-enter' when starting to view a buffer and
 132 subtracted from by `view-mode-exit' when finished viewing the buffer.
 133
 134 See RETURN-TO-ALIST argument of function `view-mode-exit' for the format of
 135 `view-return-to-alist'.")
 136 (make-obsolete-variable
 137  'view-return-to-alist "this variable is no more used." "24.1")
 138 (make-variable-buffer-local 'view-return-to-alist)
 139 (put 'view-return-to-alist 'permanent-local t)
 140
 141 (defvar view-exit-action nil
 142   "If non-nil, a function with one argument (a buffer) called when finished viewing.
 143 Commands like \\[view-file] and \\[view-file-other-window] may
 144 set this to bury or kill the viewed buffer.
 145 Observe that the buffer viewed might not appear in any window at
 146 the time this function is called.")
 147 (make-variable-buffer-local 'view-exit-action)
 148
 149 (defvar view-no-disable-on-exit nil
 150   "If non-nil, View mode \"exit\" commands don't actually disable View mode.
 151 Instead, these commands just switch buffers or windows.
 152 This is set in certain buffers by specialized features such as help commands
 153 that use View mode automatically.")
 154
 155 (defvar view-overlay nil
 156   "Overlay used to display where a search operation found its match.
 157 This is local in each buffer, once it is used.")
 158 (make-variable-buffer-local 'view-overlay)
 159 \f
 160 ;; Define keymap inside defvar to make it easier to load changes.
 161 ;; Some redundant "less"-like key bindings below have been commented out.
 162 (defvar view-mode-map
 163   (let ((map (make-sparse-keymap)))
 164     (define-key map "C" 'View-kill-and-leave)
 165     (define-key map "c" 'View-leave)
 166     (define-key map "Q" 'View-quit-all)
 167     (define-key map "E" 'View-exit-and-edit)
 168     ;; (define-key map "v" 'View-exit)
 169     (define-key map "e" 'View-exit)
 170     (define-key map "q" 'View-quit)
 171     ;; (define-key map "N" 'View-search-last-regexp-backward)
 172     (define-key map "p" 'View-search-last-regexp-backward)
 173     (define-key map "n" 'View-search-last-regexp-forward)
 174     ;; (define-key map "?" 'View-search-regexp-backward) ; Less does this.
 175     (define-key map "\\" 'View-search-regexp-backward)
 176     (define-key map "/" 'View-search-regexp-forward)
 177     (define-key map "r" 'isearch-backward)
 178     (define-key map "s" 'isearch-forward)
 179     (define-key map "m" 'point-to-register)
 180     (define-key map "'" 'register-to-point)
 181     (define-key map "x" 'exchange-point-and-mark)
 182     (define-key map "@" 'View-back-to-mark)
 183     (define-key map "." 'set-mark-command)
 184     (define-key map "%" 'View-goto-percent)
 185     ;; (define-key map "G" 'View-goto-line-last)
 186     (define-key map "g" 'View-goto-line)
 187     (define-key map "=" 'what-line)
 188     (define-key map "F" 'View-revert-buffer-scroll-page-forward)
 189     ;; (define-key map "k" 'View-scroll-line-backward)
 190     (define-key map "y" 'View-scroll-line-backward)
 191     ;; (define-key map "j" 'View-scroll-line-forward)
 192     (define-key map "\n" 'View-scroll-line-forward)
 193     (define-key map "\r" 'View-scroll-line-forward)
 194     (define-key map "u" 'View-scroll-half-page-backward)
 195     (define-key map "d" 'View-scroll-half-page-forward)
 196     (define-key map "z" 'View-scroll-page-forward-set-page-size)
 197     (define-key map "w" 'View-scroll-page-backward-set-page-size)
 198     ;; (define-key map "b" 'View-scroll-page-backward)
 199     (define-key map "\C-?" 'View-scroll-page-backward)
 200     ;; (define-key map "f" 'View-scroll-page-forward)
 201     (define-key map " " 'View-scroll-page-forward)
 202     (define-key map [?\S-\ ]  'View-scroll-page-backward)
 203     (define-key map "o" 'View-scroll-to-buffer-end)
 204     (define-key map ">" 'end-of-buffer)
 205     (define-key map "<" 'beginning-of-buffer)
 206     (define-key map "-" 'negative-argument)
 207     (define-key map "9" 'digit-argument)
 208     (define-key map "8" 'digit-argument)
 209     (define-key map "7" 'digit-argument)
 210     (define-key map "6" 'digit-argument)
 211     (define-key map "5" 'digit-argument)
 212     (define-key map "4" 'digit-argument)
 213     (define-key map "3" 'digit-argument)
 214     (define-key map "2" 'digit-argument)
 215     (define-key map "1" 'digit-argument)
 216     (define-key map "0" 'digit-argument)
 217     (define-key map "H" 'describe-mode)
 218     (define-key map "?" 'describe-mode) ; Maybe do as less instead? See above.
 219     (define-key map "h" 'describe-mode)
 220     map))
 221 \f
 222 ;;; Commands that enter or exit view mode.
 223
 224 ;; This is used when view mode is exited, to make sure we don't try to
 225 ;; kill a buffer modified by the user.  A buffer in view mode can
 226 ;; become modified if the user types C-x C-q, edits the buffer, then
 227 ;; types C-x C-q again to return to view mode.
 228 ;;;###autoload
 229 (defun kill-buffer-if-not-modified (buf)
 230   "Like `kill-buffer', but does nothing if the buffer is modified."
 231   (let ((buf (get-buffer buf)))
 232     (and buf (not (buffer-modified-p buf))
 233          (kill-buffer buf))))
 234
 235 ;;;###autoload
 236 (defun view-file (file)
 237   "View FILE in View mode, returning to previous buffer when done.
 238 Emacs commands editing the buffer contents are not available; instead, a
 239 special set of commands (mostly letters and punctuation) are defined for
 240 moving around in the buffer.
 241 Space scrolls forward, Delete scrolls backward.
 242 For a list of all View commands, type H or h while viewing.
 243
 244 This command runs the normal hook `view-mode-hook'."
 245   (interactive "fView file: ")
 246   (unless (file-exists-p file) (error "%s does not exist" file))
 247   (let ((had-a-buf (get-file-buffer file))
 248         (buffer (find-file-noselect file)))
 249     (view-buffer buffer (and (not had-a-buf) 'kill-buffer-if-not-modified))))
 250
 251 ;;;###autoload
 252 (defun view-file-other-window (file)
 253   "View FILE in View mode in another window.
 254 When done, return that window to its previous buffer, and kill the
 255 buffer visiting FILE if unmodified and if it wasn't visited before.
 256
 257 Emacs commands editing the buffer contents are not available; instead,
 258 a special set of commands (mostly letters and punctuation)
 259 are defined for moving around in the buffer.
 260 Space scrolls forward, Delete scrolls backward.
 261 For a list of all View commands, type H or h while viewing.
 262
 263 This command runs the normal hook `view-mode-hook'."
 264   (interactive "fIn other window view file: ")
 265   (unless (file-exists-p file) (error "%s does not exist" file))
 266   (let ((had-a-buf (get-file-buffer file))
 267         (buf-to-view (find-file-noselect file)))
 268     (view-buffer-other-window buf-to-view nil
 269                               (and (not had-a-buf)
 270                                    'kill-buffer-if-not-modified))))
 271
 272 ;;;###autoload
 273 (defun view-file-other-frame (file)
 274   "View FILE in View mode in another frame.
 275 When done, kill the buffer visiting FILE if unmodified and if it wasn't
 276 visited before; also, maybe delete other frame and/or return to previous
 277 buffer.
 278
 279 Emacs commands editing the buffer contents are not available; instead,
 280 a special set of commands (mostly letters and punctuation)
 281 are defined for moving around in the buffer.
 282 Space scrolls forward, Delete scrolls backward.
 283 For a list of all View commands, type H or h while viewing.
 284
 285 This command runs the normal hook `view-mode-hook'."
 286   (interactive "fIn other frame view file: ")
 287   (unless (file-exists-p file) (error "%s does not exist" file))
 288   (let ((had-a-buf (get-file-buffer file))
 289         (buf-to-view (find-file-noselect file)))
 290     (view-buffer-other-frame buf-to-view nil
 291                              (and (not had-a-buf)
 292                                   'kill-buffer-if-not-modified))))
 293
 294
 295 ;;;###autoload
 296 (defun view-buffer (buffer &optional exit-action)
 297   "View BUFFER in View mode, returning to previous buffer when done.
 298 Emacs commands editing the buffer contents are not available; instead, a
 299 special set of commands (mostly letters and punctuation) are defined for
 300 moving around in the buffer.
 301 Space scrolls forward, Delete scrolls backward.
 302 For a list of all View commands, type H or h while viewing.
 303
 304 This command runs the normal hook `view-mode-hook'.
 305
 306 Optional argument EXIT-ACTION is either nil or a function with buffer as
 307 argument.  This function is called when finished viewing buffer.  Use
 308 this argument instead of explicitly setting `view-exit-action'.
 309
 310 Do not set EXIT-ACTION to `kill-buffer' when BUFFER visits a
 311 file: Users may suspend viewing in order to modify the buffer.
 312 Exiting View mode will then discard the user's edits.  Setting
 313 EXIT-ACTION to `kill-buffer-if-not-modified' avoids this.
 314
 315 This function does not enable View mode if the buffer's major-mode
 316 has a `special' mode-class, because such modes usually have their
 317 own View-like bindings."
 318   (interactive "bView buffer: ")
 319   (switch-to-buffer buffer)
 320   (if (eq (get major-mode 'mode-class) 'special)
 321       (message "Not using View mode because the major mode is special")
 322     (view-mode-enter nil exit-action)))
 323
 324 ;;;###autoload
 325 (defun view-buffer-other-window (buffer &optional _not-return exit-action)
 326   "View BUFFER in View mode in another window.
 327 Emacs commands editing the buffer contents are not available;
 328 instead, a special set of commands (mostly letters and
 329 punctuation) are defined for moving around in the buffer.
 330 Space scrolls forward, Delete scrolls backward.
 331 For a list of all View commands, type H or h while viewing.
 332
 333 This command runs the normal hook `view-mode-hook'.
 334
 335 Optional argument NOT-RETURN is ignored.
 336
 337 Optional argument EXIT-ACTION is either nil or a function with buffer as
 338 argument.  This function is called when finished viewing buffer.  Use
 339 this argument instead of explicitly setting `view-exit-action'.
 340
 341 This function does not enable View mode if the buffer's major-mode
 342 has a `special' mode-class, because such modes usually have their
 343 own View-like bindings."
 344   (interactive "bIn other window view buffer:\nP")
 345   (let ((pop-up-windows t))
 346     (pop-to-buffer buffer t))
 347   (if (eq (get major-mode 'mode-class) 'special)
 348       (message "Not using View mode because the major mode is special")
 349     (view-mode-enter nil exit-action)))
 350
 351 ;;;###autoload
 352 (defun view-buffer-other-frame (buffer &optional _not-return exit-action)
 353   "View BUFFER in View mode in another frame.
 354 Emacs commands editing the buffer contents are not available;
 355 instead, a special set of commands (mostly letters and
 356 punctuation) are defined for moving around in the buffer.
 357 Space scrolls forward, Delete scrolls backward.
 358 For a 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 NOT-RETURN is ignored.
 363
 364 Optional argument EXIT-ACTION is either nil or a function with buffer as
 365 argument.  This function is called when finished viewing buffer.  Use
 366 this argument instead of explicitly setting `view-exit-action'.
 367
 368 This function does not enable View mode if the buffer's major-mode
 369 has a `special' mode-class, because such modes usually have their
 370 own View-like bindings."
 371   (interactive "bView buffer in other frame: \nP")
 372   (let ((pop-up-frames t))
 373     (pop-to-buffer buffer t))
 374   (if (eq (get major-mode 'mode-class) 'special)
 375       (message "Not using View mode because the major mode is special")
 376     (view-mode-enter nil exit-action)))
 377 \f
 378 ;;;###autoload
 379 (define-minor-mode view-mode
 380   ;; In the following documentation string we have to use some explicit key
 381   ;; bindings instead of using the \\[] construction.  The reason for this
 382   ;; is that most commands have more than one key binding.
 383   "Toggle View mode, a minor mode for viewing text but not editing it.
 384 With a prefix argument ARG, enable View mode if ARG is positive,
 385 and disable it otherwise.  If called from Lisp, enable View mode
 386 if ARG is omitted or nil.
 387
 388 When View mode is enabled, commands that do not change the buffer
 389 contents are available as usual.  Kill commands insert text in
 390 kill buffers but do not delete.  Most other commands beep and
 391 tell the user that the buffer is read-only.
 392
 393 \\<view-mode-map>
 394
 395 The following additional commands are provided.  Most commands
 396 take prefix arguments.  Page commands default to \"page size\"
 397 lines which is almost a whole window, or number of lines set by
 398 \\[View-scroll-page-forward-set-page-size] or \\[View-scroll-page-backward-set-page-size].
 399 Half page commands default to and set \"half page size\" lines
 400 which initially is half a window full.  Search commands default
 401 to a repeat count of one.
 402
 403 H, h, ?  This message.
 404 Digits  provide prefix arguments.
 405 \\[negative-argument]   negative prefix argument.
 406 \\[beginning-of-buffer] move to the beginning of buffer.
 407 >       move to the end of buffer.
 408 \\[View-scroll-to-buffer-end]   scroll so that buffer end is at last line of window.
 409 SPC     scroll forward \"page size\" lines.
 410           With prefix scroll forward prefix lines.
 411 DEL, S-SPC  scroll backward \"page size\" lines.
 412               With prefix scroll backward prefix lines.
 413 \\[View-scroll-page-forward-set-page-size]      like  \\[View-scroll-page-forward]  but with prefix sets \"page size\" to prefix.
 414 \\[View-scroll-page-backward-set-page-size]     like  \\[View-scroll-page-backward]  but with prefix sets \"page size\" to prefix.
 415 \\[View-scroll-half-page-forward]       scroll forward \"half page size\" lines.  With prefix, sets
 416           \"half page size\" to prefix lines and scrolls forward that much.
 417 \\[View-scroll-half-page-backward]      scroll backward \"half page size\" lines.  With prefix, sets
 418           \"half page size\" to prefix lines and scrolls backward that much.
 419 RET, LFD  scroll forward one line.  With prefix scroll forward prefix line(s).
 420 y       scroll backward one line.  With prefix scroll backward prefix line(s).
 421 \\[View-revert-buffer-scroll-page-forward]      revert-buffer if necessary and scroll forward.
 422           Use this to view a changing file.
 423 \\[what-line]   prints the current line number.
 424 \\[View-goto-percent]   goes prefix argument (default 100) percent into buffer.
 425 \\[View-goto-line]      goes to line given by prefix argument (default first line).
 426 .       set the mark.
 427 x       exchanges point and mark.
 428 \\[View-back-to-mark]   return to mark and pops mark ring.
 429           Mark ring is pushed at start of every successful search and when
 430           jump to line occurs.  The mark is set on jump to buffer start or end.
 431 \\[point-to-register]   save current position in character register.
 432 '       go to position saved in character register.
 433 s       do forward incremental search.
 434 r       do reverse incremental search.
 435 \\[View-search-regexp-forward]  searches forward for regular expression, starting after current page.
 436           ! and @ have a special meaning at the beginning of the regexp.
 437           ! means search for a line with no match for regexp.  @ means start
 438           search at beginning (end for backward search) of buffer.
 439 \\      searches backward for regular expression, starting before current page.
 440 \\[View-search-last-regexp-forward]     searches forward for last regular expression.
 441 p       searches backward for last regular expression.
 442 \\[View-quit]   quit View mode, restoring this window and buffer to previous state.
 443           \\[View-quit] is the normal way to leave view mode.
 444 \\[View-exit]   exit View mode but stay in current buffer.  Use this if you started
 445           viewing a buffer (file) and find out you want to edit it.
 446           This command restores the previous read-only status of the buffer.
 447 \\[View-exit-and-edit]  exit View mode, and make the current buffer editable
 448           even if it was not editable before entry to View mode.
 449 \\[View-quit-all]       quit View mode, restoring all windows to previous state.
 450 \\[View-leave]  quit View mode and maybe switch buffers, but don't kill this buffer.
 451 \\[View-kill-and-leave] quit View mode, kill current buffer and go back to other buffer.
 452
 453 The effect of \\[View-leave], \\[View-quit] and \\[View-kill-and-leave] depends on how view-mode was entered.  If it was
 454 entered by view-file, view-file-other-window, view-file-other-frame, or
 455 \\[dired-view-file] \(\\[view-file], \\[view-file-other-window],
 456 \\[view-file-other-frame], or the Dired mode v command),
 457 then \\[View-quit] will try to kill the current buffer.
 458 If view-mode was entered from another buffer, by \\[view-buffer],
 459 \\[view-buffer-other-window], \\[view-buffer-other frame], \\[view-file],
 460 \\[view-file-other-window], or \\[view-file-other-frame],
 461 then \\[View-leave], \\[View-quit] and \\[View-kill-and-leave] will return to that buffer.
 462
 463 Entry to view-mode runs the normal hook `view-mode-hook'."
 464   :lighter " View" :keymap view-mode-map
 465   (if view-mode (view--enable) (view--disable)))
 466 \f
 467 (defun view--enable ()
 468   ;; Always leave view mode before changing major mode.
 469   ;; This is to guarantee that the buffer-read-only variable is restored.
 470   (add-hook 'change-major-mode-hook 'view--disable nil t)
 471   (setq view-page-size nil
 472         view-half-page-size nil
 473         view-old-buffer-read-only buffer-read-only
 474         buffer-read-only t)
 475   (if (boundp 'Helper-return-blurb)
 476       (setq view-old-Helper-return-blurb (and (boundp 'Helper-return-blurb)
 477                                               Helper-return-blurb)
 478             Helper-return-blurb
 479             (format "continue viewing %s"
 480                     (if (buffer-file-name)
 481                         (file-name-nondirectory (buffer-file-name))
 482                       (buffer-name))))))
 483
 484
 485 (define-obsolete-function-alias 'view-mode-enable 'view-mode "24.4")
 486 (defun view-mode-disable ()
 487   "Turn off View mode."
 488   (declare (obsolete view-mode "24.4"))
 489   (view-mode -1))
 490
 491 (defun view--disable ()
 492   (remove-hook 'change-major-mode-hook 'view--disable t)
 493   (and view-overlay (delete-overlay view-overlay))
 494   ;; Calling read-only-mode while View mode is enabled
 495   ;; sets view-read-only to t as a buffer-local variable
 496   ;; after exiting View mode.  That arranges that the next read-only-mode
 497   ;; will reenable View mode.
 498   ;; Canceling View mode in any other way should cancel that, too,
 499   ;; so that View mode stays off if read-only-mode is called.
 500   (if (local-variable-p 'view-read-only)
 501       (kill-local-variable 'view-read-only))
 502   (if (boundp 'Helper-return-blurb)
 503       (setq Helper-return-blurb view-old-Helper-return-blurb))
 504   (if buffer-read-only
 505       (setq buffer-read-only view-old-buffer-read-only)))
 506
 507 ;;;###autoload
 508 (defun view-return-to-alist-update (buffer &optional item)
 509   "Update `view-return-to-alist' of buffer BUFFER.
 510 Remove from `view-return-to-alist' all entries referencing dead
 511 windows.  Optional argument ITEM non-nil means add ITEM to
 512 `view-return-to-alist' after purging.  For a description of items
 513 that can be added see the RETURN-TO-ALIST argument of the
 514 function `view-mode-exit'.  If `view-return-to-alist' contains an
 515 entry for the selected window, purge that entry from
 516 `view-return-to-alist' before adding ITEM."
 517   (declare (obsolete "this function has no effect." "24.1"))
 518   (with-current-buffer buffer
 519     (when view-return-to-alist
 520       (let* ((list view-return-to-alist)
 521              entry entry-window last)
 522         (while list
 523           (setq entry (car list))
 524           (setq entry-window (car entry))
 525           (if (and (windowp entry-window)
 526                    (or (and item (eq entry-window (selected-window)))
 527                        (not (window-live-p entry-window))))
 528               ;; Remove that entry.
 529               (if last
 530                   (setcdr last (cdr list))
 531                 (setq view-return-to-alist
 532                       (cdr view-return-to-alist)))
 533             ;; Leave entry alone.
 534             (setq last entry))
 535           (setq list (cdr list)))))
 536     ;; Add ITEM.
 537     (when item
 538       (setq view-return-to-alist
 539             (cons item view-return-to-alist)))))
 540
 541 ;;;###autoload
 542 (defun view-mode-enter (&optional quit-restore exit-action)
 543   "Enter View mode and set up exit from view mode depending on optional arguments.
 544 Optional argument QUIT-RESTORE if non-nil must specify a valid
 545 entry for quitting and restoring any window showing the current
 546 buffer.  This entry replaces any parameter installed by
 547 `display-buffer' and is used by `view-mode-exit'.
 548
 549 Optional argument EXIT-ACTION, if non-nil, must specify a
 550 function that takes a buffer as argument.  This function will be
 551 called by `view-mode-exit'.
 552
 553 For a list of all View commands, type H or h while viewing.
 554
 555 This function runs the normal hook `view-mode-hook'."
 556   (when quit-restore
 557     (dolist (window (get-buffer-window-list nil nil t))
 558       (set-window-parameter window 'quit-restore quit-restore)))
 559
 560   (when exit-action
 561     (setq view-exit-action exit-action))
 562
 563   (unless view-mode
 564     (view-mode 1)
 565     (unless view-inhibit-help-message
 566       (message "%s"
 567                (substitute-command-keys "\
 568 View mode: type \\[help-command] for help, \\[describe-mode] for commands, \\[View-quit] to quit.")))))
 569 \f
 570 ;; This is awful because it assumes that the selected window shows the
 571 ;; current buffer when this is called.
 572 (defun view-mode-exit (&optional exit-only exit-action all-windows)
 573   "Exit View mode in various ways.
 574 If all arguments are nil, remove the current buffer from the
 575 selected window using the `quit-restore' information associated
 576 with the selected window.  If optional argument ALL-WINDOWS or
 577 `view-exits-all-viewing-windows' are non-nil, remove the current
 578 buffer from all windows showing it.
 579
 580 Optional argument EXIT-ONLY non-nil means just exit `view-mode'
 581 \(unless `view-no-disable-on-exit' is non-nil) but do not change
 582 the associations of any windows with the current buffer.
 583
 584 EXIT-ACTION, if non-nil, must specify a function that is called
 585 with the current buffer as argument and is called after disabling
 586 `view-mode' and removing any associations of windows with the
 587 current buffer. "
 588   (when view-mode
 589     (let ((buffer (window-buffer)))
 590       (unless view-no-disable-on-exit
 591         (view-mode -1))
 592
 593       (unless exit-only
 594         (cond
 595          ((or all-windows view-exits-all-viewing-windows)
 596           (dolist (window (get-buffer-window-list))
 597             (quit-window nil window)))
 598          ((eq (window-buffer) (current-buffer))
 599           (quit-window)))
 600
 601         (when exit-action
 602           (funcall exit-action buffer))))))
 603 \f
 604 (defun View-exit ()
 605   "Exit View mode but stay in current buffer."
 606   (interactive)
 607   (view-mode-exit t))
 608
 609 ;;;###autoload
 610 (defun View-exit-and-edit ()
 611   "Exit View mode and make the current buffer editable."
 612   (interactive)
 613   (let ((view-old-buffer-read-only nil)
 614         (view-no-disable-on-exit nil))
 615     (view-mode-exit t)))
 616
 617 (defun View-leave ()
 618   "Quit View mode and maybe switch buffers, but don't kill this buffer."
 619   (interactive)
 620   (view-mode-exit))
 621
 622 (defun View-quit ()
 623   "Quit View mode, trying to restore window and buffer to previous state.
 624 Maybe kill this buffer.  Try to restore selected window to previous state
 625 and go to previous buffer or window."
 626   (interactive)
 627   (view-mode-exit nil view-exit-action))
 628
 629 (defun View-quit-all ()
 630   "Quit View mode, trying to restore windows and buffers to previous state.
 631 Maybe kill current buffer.  Try to restore all windows viewing buffer to
 632 previous state and go to previous buffer or window."
 633   (interactive)
 634   (view-mode-exit nil view-exit-action t))
 635
 636 (defun View-kill-and-leave ()
 637   "Quit View mode, kill current buffer and return to previous buffer."
 638   (interactive)
 639   (view-mode-exit nil (or view-exit-action 'kill-buffer) t))
 640 \f
 641
 642 ;;; Some help routines.
 643
 644 (defun view-window-size ()
 645   ;; Return the height of the current window, excluding the mode line.
 646   ;; Using `window-line-height' accounts for variable-height fonts.
 647   (let ((h (window-line-height -1)))
 648     (if h
 649         (1+ (nth 1 h))
 650       ;; This should not happen, but if `window-line-height' returns
 651       ;; nil, fall back on `window-height'.
 652       (1- (window-height)))))
 653
 654 ;; (defun view-last-command (&optional who what)
 655 ;;  (setq view-last-command-entry this-command)
 656 ;;  (setq view-last-command who)
 657 ;;  (setq view-last-command-argument what))
 658
 659 ;; (defun View-repeat-last-command ()
 660 ;;  "Repeat last command issued in View mode."
 661 ;;  (interactive)
 662 ;;  (if (and view-last-command
 663 ;;         (eq view-last-command-entry last-command))
 664 ;;      (funcall view-last-command view-last-command-argument))
 665 ;;  (setq this-command view-last-command-entry))
 666
 667 (defun view-recenter ()
 668   ;; Recenter point in window and redisplay normally.
 669   (recenter '(1)))
 670
 671 (defun view-page-size-default (lines)
 672   ;; If LINES is nil, 0, or larger than `view-window-size', return nil.
 673   ;; Otherwise, return LINES.
 674   (and lines
 675        (not (zerop (setq lines (prefix-numeric-value lines))))
 676        (<= (abs lines)
 677            (abs (- (view-window-size) next-screen-context-lines)))
 678        (abs lines)))
 679
 680 (defun view-set-half-page-size-default (lines)
 681   ;; Get and maybe set half page size.
 682   (if (not lines) (or view-half-page-size
 683                       (/ (view-window-size) 2))
 684     (setq view-half-page-size
 685           (if (zerop (setq lines (prefix-numeric-value lines)))
 686               (/ (view-window-size) 2)
 687             (view-page-size-default lines)))))
 688
 689
 690 ;;; Commands for moving around in the buffer.
 691
 692 (defun View-goto-percent (&optional percent)
 693   "Move to end (or prefix PERCENT) of buffer in View mode.
 694 Display is centered at point.
 695 Also set the mark at the position where point was."
 696   (interactive "P")
 697   (push-mark)
 698   (goto-char
 699    (if percent
 700        (+ (point-min)
 701           (floor (* (- (point-max) (point-min)) 0.01
 702                     (max 0 (min 100 (prefix-numeric-value percent))))))
 703      (point-max)))
 704   (view-recenter))
 705
 706 ;; (defun View-goto-line-last (&optional line)
 707 ;; "Move to last (or prefix LINE) line in View mode.
 708 ;; Display is centered at LINE.
 709 ;; Sets mark at starting position and pushes mark ring."
 710 ;;  (interactive "P")
 711 ;;  (push-mark)
 712 ;;  (if line (goto-line (prefix-numeric-value line))
 713 ;;    (goto-char (point-max))
 714 ;;    (beginning-of-line))
 715 ;;  (view-recenter))
 716
 717 (defun View-goto-line (&optional line)
 718   "Move to first (or prefix LINE) line in View mode.
 719 Display is centered at LINE.
 720 Also set the mark at the position where point was."
 721   (interactive "p")
 722   (push-mark)
 723   (goto-char (point-min))
 724   (forward-line (1- line))
 725   (view-recenter))
 726
 727 (defun View-back-to-mark (&optional _ignore)
 728   "Return to last mark set in View mode, else beginning of file.
 729 Display that line at the center of the window.
 730 This command pops the mark ring, so that successive
 731 invocations return to earlier marks."
 732   (interactive)
 733   (goto-char (or (mark t) (point-min)))
 734   (pop-mark)
 735   (view-recenter))
 736 \f
 737 (defun view-scroll-lines (lines backward default maxdefault)
 738   ;; This function does the job for all the scrolling commands.
 739   ;; Scroll forward LINES lines.  If BACKWARD is non-nil, scroll backwards.
 740   ;; If LINES is negative scroll in the other direction.
 741   ;; If LINES is 0 or nil, scroll DEFAULT lines (if DEFAULT is nil, scroll
 742   ;; by one page).  If MAXDEFAULT is non-nil, scroll no more than a window.
 743   (if (or (null lines) (zerop (setq lines (prefix-numeric-value lines))))
 744       (setq lines default))
 745   (when (and lines (< lines 0))
 746     (setq backward (not backward) lines (- lines)))
 747   (when (and maxdefault lines (> lines (view-window-size)))
 748     (setq lines nil))
 749   (cond (backward (scroll-down lines))
 750         ((view-really-at-end)
 751          (if view-scroll-auto-exit
 752              (View-quit)
 753            (ding)
 754            (view-end-message)))
 755         (t (scroll-up lines)
 756            (if (view-really-at-end) (view-end-message)))))
 757
 758 (defun view-really-at-end ()
 759   ;; Return true if buffer end visible.  Maybe revert buffer and test.
 760   (and (pos-visible-in-window-p (point-max))
 761        (let ((buf (current-buffer))
 762              (bufname (buffer-name))
 763              (file (buffer-file-name)))
 764          (or (not view-try-extend-at-buffer-end)
 765              (null file)
 766              (verify-visited-file-modtime buf)
 767              (not (file-exists-p file))
 768              (when (buffer-modified-p buf)
 769                (setq file (file-name-nondirectory file))
 770                (not (yes-or-no-p
 771                      (format
 772                       "File %s changed on disk.  Discard your edits%s? "
 773                       file
 774                       (if (string= bufname file) ""
 775                         (concat " in " bufname))))))
 776              (progn
 777                (revert-buffer t t t)
 778                (pos-visible-in-window-p (point-max)))))))
 779
 780 (defun view-end-message ()
 781   ;; Tell that we are at end of buffer.
 782   (goto-char (point-max))
 783   (if (window-parameter nil 'quit-restore)
 784       (message "End of buffer.  Type %s to quit viewing."
 785                (substitute-command-keys
 786                 (if view-scroll-auto-exit "\\[View-scroll-page-forward]"
 787                   "\\[View-quit]")))
 788     (message "End of buffer")))
 789 \f
 790 (defun View-scroll-to-buffer-end ()
 791   "Scroll backward or forward so that buffer end is at last line of window."
 792   (interactive)
 793   (let ((p (if (pos-visible-in-window-p (point-max)) (point))))
 794     (goto-char (point-max))
 795     (recenter -1)
 796     (and p (goto-char p))))
 797
 798 (defun View-scroll-page-forward (&optional lines)
 799   "Scroll \"page size\" or prefix LINES lines forward in View mode.
 800 Exit if end of text is visible and `view-scroll-auto-exit' is non-nil.
 801 \"page size\" is whole window full, or number of lines set by
 802 \\[View-scroll-page-forward-set-page-size] or
 803 \\[View-scroll-page-backward-set-page-size].
 804 If LINES is more than a window-full, only the last window-full is shown."
 805   (interactive "P")
 806   (view-scroll-lines lines nil (view-page-size-default view-page-size) nil))
 807
 808 (defun View-scroll-page-backward (&optional lines)
 809   "Scroll \"page size\" or prefix LINES lines backward in View mode.
 810 See also `View-scroll-page-forward'."
 811   (interactive "P")
 812   (view-scroll-lines lines t (view-page-size-default view-page-size) nil))
 813
 814 (defun View-scroll-page-forward-set-page-size (&optional lines)
 815   "Scroll forward LINES lines in View mode, setting the \"page size\".
 816 This is the number of lines which \\[View-scroll-page-forward] and
 817 \\[View-scroll-page-backward] scroll by default.
 818 If LINES is omitted or = 0, sets \"page size\" to window height and
 819 scrolls forward that much, otherwise scrolls forward LINES lines and sets
 820 \"page size\" to the minimum of window height and the absolute value of LINES.
 821 See also `View-scroll-page-forward'."
 822   (interactive "P")
 823   (view-scroll-lines lines nil
 824                      (setq view-page-size (view-page-size-default lines))
 825                      nil))
 826
 827 (defun View-scroll-page-backward-set-page-size (&optional lines)
 828   "Scroll backward prefix LINES lines in View mode, setting the \"page size\".
 829 See also `View-scroll-page-forward-set-page-size'."
 830   (interactive "P")
 831   (view-scroll-lines lines t
 832                      (setq view-page-size (view-page-size-default lines))
 833                      nil))
 834
 835 (defun View-scroll-line-forward (&optional lines)
 836   "Scroll forward one line (or prefix LINES lines) in View mode.
 837 See also `View-scroll-page-forward', but note that scrolling is limited
 838 to minimum of LINES and one window-full."
 839   (interactive "P")
 840   (view-scroll-lines lines nil 1 t))
 841
 842 (defun View-scroll-line-backward (&optional lines)
 843   "Scroll backward one line (or prefix LINES lines) in View mode.
 844 See also `View-scroll-line-forward'."
 845   (interactive "P")
 846   (view-scroll-lines lines t 1 t))
 847
 848 (defun View-scroll-half-page-forward (&optional lines)
 849   "Scroll forward a \"half page\" (or prefix LINES) lines in View mode.
 850 If LINES is not omitted, the \"half page size\" is set to the minimum of
 851 window height and the absolute value of LINES.
 852 LINES=0 resets \"half page size\" to half window height."
 853   (interactive "P")
 854   (view-scroll-lines lines nil (view-set-half-page-size-default lines) t))
 855
 856 (defun View-scroll-half-page-backward (&optional lines)
 857   "Scroll backward a \"half page\" (or prefix LINES) lines in View mode.
 858 See also `View-scroll-half-page-forward'."
 859   (interactive "P")
 860   (view-scroll-lines lines t (view-set-half-page-size-default lines) t))
 861
 862 (defun View-revert-buffer-scroll-page-forward (&optional lines)
 863   "Scroll forward, reverting buffer if needed, in View mode.
 864 If buffer has not been changed and the corresponding file is newer, first
 865 revert the buffer, then scroll.
 866 This command is useful if you are viewing a changing file.
 867
 868 The prefix argument LINES says how many lines to scroll.
 869 If you don't specify a prefix argument, it uses the number of lines set by
 870 \\[View-scroll-page-forward-set-page-size] or
 871 \\[View-scroll-page-backward-set-page-size].
 872 If LINES is more than a window-full, only the last window-full is shown."
 873   (interactive "P")
 874   (let ((view-scroll-auto-exit nil)
 875         (view-try-extend-at-buffer-end t))
 876     (view-scroll-lines lines nil (view-page-size-default view-page-size) nil)))
 877 \f
 878 (defun View-search-regexp-forward (n regexp)
 879   "Search forward for first (or prefix Nth) occurrence of REGEXP in View mode.
 880
 881 Displays line found at center of window.  Sets mark at starting position and
 882 pushes mark ring.
 883
 884 Characters @ and ! are special at the beginning of REGEXP.  They modify
 885 the search rather than become part of the pattern searched for.
 886 @ means search all the buffer i.e. start search at the beginning of buffer.
 887 ! means search for a line that contains no match for the pattern.
 888 If REGEXP is empty or only consist of these control characters, then
 889 an earlier remembered REGEXP is used, otherwise REGEXP is remembered
 890 for use by later search commands.
 891
 892 The variable `view-highlight-face' controls the face that is used
 893 for highlighting the match that is found."
 894   (interactive "p\nsSearch forward (regexp): ")
 895   (view-search n regexp))
 896
 897 (defun View-search-regexp-backward (n regexp)
 898   "Search backward for first (or prefix Nth) occurrence of REGEXP in View mode.
 899
 900 Displays line found at center of window.  Sets mark at starting position and
 901 pushes mark ring.
 902
 903 Characters @ and ! are special at the beginning of REGEXP.  They modify
 904 the search rather than become part of the pattern searched for.
 905 @ means search all the buffer i.e. start search at the end of buffer.
 906 ! means search for a line that contains no match for the pattern.
 907 If REGEXP is empty or only consist of these control characters, then
 908 an earlier remembered REGEXP is used, otherwise REGEXP is remembered
 909 for use by later search commands.
 910
 911 The variable `view-highlight-face' controls the face that is used
 912 for highlighting the match that is found."
 913   (interactive "p\nsSearch backward (regexp): ")
 914   (view-search (- n) regexp))
 915
 916 (defun View-search-last-regexp-forward (n) "\
 917 Search forward for first (or prefix Nth) instance of last regexp in View mode.
 918 Displays line found at center of window.  Sets mark at starting position and
 919 pushes mark ring.
 920
 921 The variable `view-highlight-face' controls the face that is used
 922 for highlighting the match that is found."
 923   (interactive "p")
 924   (view-search n nil))
 925
 926 (defun View-search-last-regexp-backward (n) "\
 927 Search backward for first (or prefix Nth) instance of last regexp in View mode.
 928 Displays line found at center of window.  Sets mark at starting position and
 929 pushes mark ring.
 930
 931 The variable `view-highlight-face' controls the face that is used
 932 for highlighting the match that is found."
 933   (interactive "p")
 934   (view-search (- n) nil))
 935
 936 (defun view-search (times regexp)
 937   ;; This function does the job for all the View-search- commands.
 938   ;; Search for the TIMESth match for REGEXP.  If TIMES is negative
 939   ;; search backwards.  If REGEXP is nil use `view-last-regexp'.
 940   ;; Characters "!" and "@" have a special meaning at the beginning of
 941   ;; REGEXP and are removed from REGEXP before the search "!" means
 942   ;; search for lines with no match for REGEXP.  "@" means search in
 943   ;; the whole buffer, don't start searching from the present point.
 944   (let (where no end ln)
 945     (cond
 946      ((and regexp (> (length regexp) 0)
 947            (or (not (memq (string-to-char regexp) '(?! ?@)))
 948                (progn
 949                  (if (member (substring regexp 0 2) '("!@" "@!"))
 950                      (setq end t no t ln 2)
 951                    (setq no (not (setq end (eq ?@ (string-to-char regexp))))
 952                          ln 1))
 953                  (> (length (setq regexp (substring regexp ln))) 0))))
 954       (setq view-last-regexp (if no (list regexp) regexp)))
 955      ((consp view-last-regexp)
 956       (setq regexp (car view-last-regexp))
 957       (unless (setq no (not no)) (setq view-last-regexp regexp)))
 958      (view-last-regexp (setq regexp view-last-regexp)
 959                        (if no (setq view-last-regexp (list regexp))))
 960      (t (error "No previous View-mode search")))
 961     (save-excursion
 962       (if end (goto-char (if (< times 0) (point-max) (point-min)))
 963         (move-to-window-line (if (< times 0) 0 -1)))
 964       (if (if no (view-search-no-match-lines times regexp)
 965             (re-search-forward regexp nil t times))
 966           (setq where (point))))
 967     (if where
 968         (progn
 969           (push-mark)
 970           (goto-char where)
 971           (if view-overlay
 972               (move-overlay view-overlay (match-beginning 0) (match-end 0))
 973             (setq view-overlay
 974                   (make-overlay (match-beginning 0) (match-end 0))))
 975           (overlay-put view-overlay 'face view-highlight-face)
 976           (beginning-of-line)
 977           (view-recenter))
 978       (message "Can't find occurrence %d of %s%s"
 979                times (if no "no " "") regexp)
 980       (sit-for 4))))
 981
 982 ;; This is the dumb approach, looking at each line.  The original
 983 ;; version of this function looked like it might have been trying to
 984 ;; do something clever, but not succeeding:
 985 ;; http://lists.gnu.org/archive/html/bug-gnu-emacs/2007-09/msg00073.html
 986 (defun view-search-no-match-lines (times regexp)
 987   "Search for the TIMESth occurrence of a line with no match for REGEXP.
 988 If such a line is found, return non-nil and set the match-data to that line.
 989 If TIMES is negative, search backwards."
 990   (let ((step (if (>= times 0) 1
 991                 (setq times (- times))
 992                 -1)))
 993     ;; Note that we do not check the current line.
 994     (while (and (> times 0)
 995                 (zerop (forward-line step)))
 996       ;; (forward-line 1) returns 0 on moving within the last line.
 997       (if (eobp)
 998           (setq times -1)
 999         (or (re-search-forward regexp (line-end-position) t)
1000             (setq times (1- times))))))
1001   (and (zerop times)
1002        (looking-at ".*")))
1003
1004 (provide 'view)
1005
1006 ;;; view.el ends here