lisp/textmodes/two-column.el

   1 ;;; two-column.el --- minor mode for editing of two-column text
   2
   3 ;; Copyright (C) 1992, 1993, 1994, 1995, 2001, 2002, 2003, 2004,
   4 ;;   2005, 2006, 2007, 2008 Free Software Foundation, Inc.
   5
   6 ;; Author: Daniel Pfeiffer <occitan@esperanto.org>
   7 ;; Adapted-By: ESR, Daniel Pfeiffer
   8 ;; Keywords: wp
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; Esperanto:                            English:
  13
  14 ;; ^Ci dosiero estas ero de GNU Emacs.   This file is part of GNU Emacs.
  15
  16 ;; GNU  Emacs estas libera  programaro;  GNU Emacs is free software; you can
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  18 ;; ^gin sub  la  kondi^coj  de  la  GNU  under the terms of the GNU General
  19 ;; ^Generala  Publika Licenco kiel pub-  Public License as published by the
  20 ;; likigita far la Liberprogramara Fon-  Free Software Foundation; either
  21 ;; da^jo; a^u eldono 2a,  a^u (la^u via  version 3, or (at your option) any
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  30 ;; detaloj.                              for more details.
  31
  32 ;; Vi devus ricevinti kopion de la  GNU  You should have received a copy of
  33 ;; ^Generala  Publika  Licenco kune kun  the GNU General Public License along
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  35 ;; Alikaze skribu al la                  COPYING.  If not, write to the
  36
  37 ;; Free Software Foundation, 51 Franklin Street, Fifth Floor
  38 ;; Boston, MA 02110-1301, USA.
  39
  40 ;;; Commentary:
  41
  42 ;;; Komentario:                          Commentary:
  43
  44 ;; Tiu  programaro ebligas  vin redakti  This package gives you the ability
  45 ;; dukolumnan tekston.                   to edit text in a two-column format.
  46
  47
  48 ;; Vi  havas  tri eblecojn por eki tiun  You have three ways to start up this
  49 ;; mal^cefan modalon.  ^Ciu donas al vi  minor mode.  Each gives you a
  50 ;; horizontale disigatan fenestron, si-  horizontally split window similar to
  51 ;; milan al fina apareco de via teksto:  the final outcome of your text:
  52
  53
  54 ;; f2 2     asocias  novan  bufron  nomatan  associates a new  buffer called
  55 ;; C-x 6 2  same, sed kun 2C/ anta^u.        the   same,    but   with   2C/
  56 ;;                                           prepended.
  57
  58 ;; f2 b     asocias alian bufron.  Vi povas  associates    another   buffer.
  59 ;; C-x 6 b  anka^u asocii  dataron,   se vi  This can be used to associate a
  60 ;;          ^jus anta^ue faris C-x C-f.      file if you just did C-x C-f.
  61
  62 ;; f2 s     disigas  jam dukolumnan tekston  splits a  two-column  text into
  63 ;; C-x 6 s  en  du   bufroj  ekde  la  nuna  two  buffers from  the  current
  64 ;;          linio,  kaj je la nuna kolumno.  line and at the current column.
  65 ;;          La    anta^uaj   signoj   (ofte  The preceding characters (often
  66 ;;          tabeligilo  a^u  |)  estas   la  tab   or  |)  are   the  column
  67 ;;          kolumna disiganto.  Linioj kiuj  separator.   Lines  that  don't
  68 ;;          ne   enhavas   ilin   ne  estas  have them  won't  be separated.
  69 ;;          disigitaj.   Kiel  la kvara kaj  Like the  fourth and fifth line
  70 ;;          la   kvina  linio se vi disigas  if  you split this  file from
  71 ;;          ^ci dataron ekde la unua  angla  the first english word.
  72 ;;          vorto.
  73
  74 ;; Se  vi  volas  meti  longajn liniojn  If you include long lines, i.e which
  75 ;; (ekz. programerojn) en la  kunigotan  will span both columns  (eg.  source
  76 ;; tekston,   ili  devas  esti  en   la  code), they should  be  in what will
  77 ;; estonte unua kolumno.  La alia devas  be the    first column,    with  the
  78 ;; havi vakajn linion apud ili.          associated buffer having empty lines
  79 ;;                                       next to them.
  80
  81 ;; Averto: en Emacs kiam vi ^san^gas la  Attention:  in Emacs when you change
  82 ;; ^cefan modalon, la mal^cefaj modaloj  the major mode,  the minor modes are
  83 ;; estas  anka^u  elmemorigitaj.   Tiu-  also  purged  from  memory.  In that
  84 ;; okaze  vi devas religi la du bufrojn  case you   must  reassociate the two
  85 ;; per iu  C-x 6-ordono,  ekz. C-x 6 b.  buffers with any C-x 6-command, e.g.
  86 ;;                                       C-x 6 b.
  87
  88 ;; Kiam   vi   estos  kontenta   de  la  When you have edited both buffers to
  89 ;; rezulto, vi kunmetos la du kolumnojn  your  content,  you merge them  with
  90 ;; per  C-x 6 1.   Se  vi  poste  vidas  C-x 6 1.  If you then see a problem,
  91 ;; problemon, vi  neniigu   la kunmeton  you undo the  merge with  C-x u  and
  92 ;; per C-x u  kaj  plue  modifu  la  du  continue   to  edit the two buffers.
  93 ;; bufrojn.  Kiam vi ne plu volas tajpi  When you  no longer  want to edit in
  94 ;; dukolumne,  vi  eliru el la mal^cefa  two  columns, you turn off the minor
  95 ;; modalo per C-x 6 d.                   mode with C-x 6 d.
  96
  97
  98 ;; Aldone al dukolumna  redaktado,  ek-  In addition to two-column editing of
  99 ;; zemple por  skribi dulingvan tekston  text, for example for writing a
 100 ;; flank-al-flanke kiel ^ci tiu,  aliaj  bilingual text side-by-side as shown
 101 ;; interesaj uzoj trovitas por tiu mal-  here, other interesting uses have
 102 ;; ^cefa modalo:                         been found for this minor mode:
 103
 104 ;; Vi povas  disigi la  kolumnojn per {+} You can separate the columns with
 105 ;; ajna   pla^ca   ^ceno   starigante {+} any string that pleases you, by
 106 ;; `2C-separator'.   Ekzemple  "{+} " {+} setting `2C-separator'.  For example
 107 ;; por  amuzi^gi.  f2 s  a^u  C-x 6 s {+} "{+} " if you'd like to have fun.
 108 ;; traktas   tiujn    kun    prefiksa {+} f2 s or C-x 6 s handles these with a
 109 ;; argumento  kiu  signifas la longon {+} prefix argument that means the
 110 ;; de tia ^ceno.                      {+} desired length of such a string.
 111
 112
 113 ;; Programistoj eble ^satus la  eblecon  Programmers might like the ability
 114 ;; forspliti la komentarian kolumnon de  to split off the comment column of a
 115 ;; dosiero  kiel la sekvanta.  Vi povas  file that looks like the following.
 116 ;; rearan^gigi  la paragrafon.  La pro-  You can fill-paragraph the comment.
 117 ;; blemo  estas  ke  koda^jo tuj   lar-  The problem is, code quickly gets
 118 ;; ^gi^gas,  tiel  ke vi  bezonas   pli  rather wide, so you need to use a
 119 ;; mallar^gan   komentarian   kolumnon.  narrower comment column.  Code lines
 120 ;; Koda^jaj linioj tra `comment-column'  that reach beyond `comment-column'
 121 ;; ne problemas,  krom  ke vi ne  vidos  are no problem, except that you
 122 ;; iliajn finojn dum redaktado.          won't see their end during editing.
 123
 124
 125 ;; BEGIN                                -- This is just some meaningless
 126 ;;     FOR i IN 1..10 LOOP              -- code in Ada, that runs foobar
 127 ;;         foobar( i );                 -- once for each argument from one
 128 ;;     END LOOP;                        -- to ten, and then we're already
 129 ;; END;                                 -- through with it.
 130
 131 ;; Pli bone ankora^u, vi povas  pozici-  Better yet, you can put the point
 132 ;; i^gi anta^u "This",  tajpi  M-3 f2 s  before "This", type  M-3 f2 s
 133 ;; kiu  igas "-- " la separigilon inter  which makes "-- " the separator
 134 ;; senkomentaria  Ada  bufro  kaj  nur-  between a no-comments Ada buffer,
 135 ;; teksta  komentaria  bufro.   Kiam vi  and a plain text comment buffer.
 136 ;; denove  kuni^gos ilin,  ^ciu  nevaka  When you put them back together,
 137 ;; linio  de  l'  dua  kolumno   denove  every non-empty line of the 2nd
 138 ;; anta^uhavos "-- ".                    column will again be preceded by
 139 ;;                                       "-- ".
 140
 141
 142 ;;; Code:
 143 \f
 144
 145 ;; Lucid patch
 146 (or (fboundp 'frame-width)
 147     (fset 'frame-width 'screen-width))
 148
 149
 150 ;;;;; Set up keymap ;;;;;
 151
 152 (defvar 2C-mode-map
 153   (let ((map (make-sparse-keymap)))
 154     (define-key map "2" '2C-two-columns)
 155     (define-key map [f2] '2C-two-columns)
 156     (define-key map "b" '2C-associate-buffer)
 157     (define-key map "s" '2C-split)
 158     map)
 159   "Keymap for commands for setting up two-column mode.")
 160
 161
 162
 163 ;;;###autoload (autoload '2C-command "two-column" () t 'keymap)
 164 (fset '2C-command 2C-mode-map)
 165
 166 ;; This one is for historical reasons and simple keyboards, it is not
 167 ;; at all mnemonic.  All usual sequences containing 2 were used, and
 168 ;; f2 could not be set up in a standard way under Emacs 18.
 169 ;;;###autoload (global-set-key "\C-x6" '2C-command)
 170
 171 ;;;###autoload (global-set-key [f2] '2C-command)
 172
 173
 174 (defvar 2C-minor-mode-map
 175   (let ((map (make-sparse-keymap)))
 176     (define-key map "1" '2C-merge)
 177     (define-key map "d" '2C-dissociate)
 178     (define-key map "o" '2C-associated-buffer)
 179     (define-key map "\^m" '2C-newline)
 180     (define-key map "|" '2C-toggle-autoscroll)
 181     (define-key map "{" '2C-shrink-window-horizontally)
 182     (define-key map "}" '2C-enlarge-window-horizontally)
 183     map)
 184   "Keymap for commands for use in two-column mode.")
 185
 186
 187 (setq minor-mode-map-alist
 188       (cons (cons '2C-mode
 189                   (let ((map (make-sparse-keymap)))
 190                     (substitute-key-definition '2C-command 2C-minor-mode-map
 191                                                map (current-global-map))
 192                     (substitute-key-definition 'enlarge-window-horizontally
 193                                                '2C-enlarge-window-horizontally
 194                                                map (current-global-map))
 195                     (substitute-key-definition 'shrink-window-horizontally
 196                                                '2C-shrink-window-horizontally
 197                                                map (current-global-map))
 198                     map))
 199             minor-mode-map-alist))
 200 \f
 201 ;;;;; variable declarations ;;;;;
 202
 203 (defgroup two-column nil
 204   "Minor mode for editing of two-column text."
 205   :prefix "2C-"
 206   :group 'frames)
 207
 208
 209 ;; Markers seem to be the only buffer-id not affected by renaming a buffer.
 210 ;; This nevertheless loses when a buffer is killed.  The variable-name is
 211 ;; required by `describe-mode'.
 212 (defvar 2C-mode nil
 213   "Marker to the associated buffer, if non-nil.")
 214 (make-variable-buffer-local '2C-mode)
 215 (put '2C-mode 'permanent-local t)
 216
 217
 218
 219 (setq minor-mode-alist (cons '(2C-mode " 2C") minor-mode-alist))
 220
 221
 222
 223 ;; rearranged, so that the pertinent info will show in 40 columns
 224 (defcustom 2C-mode-line-format
 225         '("-%*- %15b --"  (-3 . "%p")  "--%[("  mode-name
 226           minor-mode-alist  "%n"  mode-line-process  ")%]%-")
 227   "*Value of `mode-line-format' for a buffer in two-column minor mode."
 228   :type 'sexp
 229   :group 'two-column)
 230
 231
 232 (defcustom 2C-other-buffer-hook 'text-mode
 233   "*Hook run in new buffer when it is associated with current one."
 234   :type 'function
 235   :group 'two-column)
 236
 237
 238 (defcustom 2C-separator ""
 239   "*A string inserted between the two columns when merging.
 240 This gets set locally by \\[2C-split]."
 241   :type 'string
 242   :group 'two-column)
 243 (put '2C-separator 'permanent-local t)
 244
 245
 246
 247 (defcustom 2C-window-width 40
 248   "*The width of the first column.  (Must be at least `window-min-width')
 249 This value is local for every buffer that sets it."
 250   :type 'integer
 251   :group 'two-column)
 252 (make-variable-buffer-local '2C-window-width)
 253 (put '2C-window-width 'permanent-local t)
 254
 255
 256
 257 (defcustom 2C-beyond-fill-column 4
 258   "*Base for calculating `fill-column' for a buffer in two-column minor mode.
 259 The value of `fill-column' becomes `2C-window-width' for this buffer
 260 minus this value."
 261   :type 'integer
 262   :group 'two-column)
 263
 264
 265
 266 (defcustom 2C-autoscroll t
 267   "If non-nil, Emacs attempts to keep the two column's buffers aligned."
 268   :type 'boolean
 269   :group 'two-column)
 270
 271
 272
 273 (defvar 2C-autoscroll-start nil)
 274 (make-variable-buffer-local '2C-autoscroll-start)
 275 \f
 276 ;;;;; base functions ;;;;;
 277
 278 ;; The access method for the other buffer.  This tries to remedy against
 279 ;; lost local variables and lost buffers.
 280 (defun 2C-other (&optional req)
 281   (or (if 2C-mode
 282           (or (prog1
 283                   (marker-buffer 2C-mode)
 284                 (setq mode-line-format 2C-mode-line-format))
 285               ;; The associated buffer somehow got killed.
 286               (progn
 287                 ;; The other variables may later be useful if the user
 288                 ;; reestablishes the association.
 289                 (kill-local-variable '2C-mode)
 290                 (kill-local-variable 'mode-line-format)
 291                 nil)))
 292       (if req (error "You must first set two-column minor mode"))))
 293
 294
 295
 296 ;; function for setting up two-column minor mode in a buffer associated
 297 ;; with the buffer pointed to by the marker other.
 298 (defun 2C-mode (other)
 299   "Minor mode for independently editing two columns.
 300 This is set up for two associated buffers by the three commands bound
 301 to  \\[2C-two-columns] ,  \\[2C-associate-buffer]  and  \\[2C-split].
 302 Turning on two-column mode calls the value of the variable `2C-mode-hook',
 303 if that value is non-nil.
 304
 305 These buffers can be edited separately, for example with `fill-paragraph'.
 306 If you want to disable parallel scrolling temporarily, use  \\[2C-toggle-autoscroll] .
 307
 308 If you include long lines, i.e which will span both columns (eg.
 309 source code), they should be in what will be the first column, with
 310 the associated buffer having empty lines next to them.
 311
 312 Potential uses are writing bilingual texts, or editing the comments of a
 313 source code.  See the file lisp/two-column.el for detailed examples.
 314
 315 You have the following commands at your disposal:
 316
 317 \\[2C-two-columns]   Rearrange screen with current buffer first
 318 \\[2C-associate-buffer]   Reassociate buffer after changing major mode
 319 \\[shrink-window-horizontally], \\[enlarge-window-horizontally]   Shrink, enlarge current column
 320 \\[2C-associated-buffer]   Switch to associated buffer at same point
 321 \\[2C-newline] Insert newline(s) in both buffers at same point
 322 \\[2C-merge]   Merge both buffers
 323 \\[2C-dissociate]   Dissociate the two buffers
 324
 325 These keybindings can be customized in your ~/.emacs by `2C-mode-map',
 326 `2C-minor-mode-map' and by binding `2C-command' to some prefix.
 327
 328 The appearance of the screen can be customized by the variables
 329 `2C-window-width', `2C-beyond-fill-column', `2C-mode-line-format' and
 330 `truncate-partial-width-windows'."
 331   (add-hook 'post-command-hook '2C-autoscroll nil t)
 332   (setq fill-column (- 2C-window-width
 333                        2C-beyond-fill-column)
 334         mode-line-format 2C-mode-line-format
 335         2C-mode other)
 336   (run-hooks '2C-mode-hook))
 337
 338
 339
 340 ;;;###autoload
 341 (defun 2C-two-columns (&optional buffer)
 342   "Split current window vertically for two-column editing.
 343 \\<global-map>When called the first time, associates a buffer with the current
 344 buffer in two-column minor mode (use \\[describe-mode] once in the mode,
 345 for details.).  It runs `2C-other-buffer-hook' in the new buffer.
 346 When called again, restores the screen layout with the current buffer
 347 first and the associated buffer to its right."
 348   (interactive "P")
 349   ;; first go to full width, so that we can certainly split into two windows
 350   (unless (window-full-width-p)
 351     (enlarge-window 99999 t))
 352   (split-window-horizontally
 353    (max window-min-width (min 2C-window-width
 354                               (- (frame-width) window-min-width))))
 355   (if (2C-other)
 356       (progn
 357         (other-window 1)
 358         (switch-to-buffer (2C-other))
 359         (other-window -1)
 360         (if 2C-autoscroll
 361             (2C-toggle-autoscroll t)))
 362
 363     (2C-mode (prog1 (point-marker)
 364                (other-window 1)
 365                (switch-to-buffer
 366                 (or buffer
 367                     (generate-new-buffer (concat "2C/" (buffer-name)))))
 368                (or buffer
 369                    (run-hooks '2C-other-buffer-hook))))
 370
 371     (2C-mode (prog1 (point-marker)
 372                (other-window -1)))))
 373
 374
 375
 376 ;;;###autoload
 377 (defun 2C-associate-buffer ()
 378   "Associate another buffer with this one in two-column minor mode.
 379 Can also be used to associate a just previously visited file, by
 380 accepting the proposed default buffer.
 381
 382 \(See  \\[describe-mode] .)"
 383   (interactive)
 384   (let ((b1 (current-buffer))
 385         (b2 (or (2C-other)
 386                 (read-buffer "Associate buffer: " (other-buffer)))))
 387     (save-excursion
 388       (setq 2C-mode nil)
 389       (set-buffer b2)
 390       (and (2C-other)
 391            (not (eq b1 (2C-other)))
 392            (error "Buffer already associated with buffer `%s'"
 393                   (buffer-name (2C-other))))
 394       (setq b1 (and (assq '2C-window-width (buffer-local-variables))
 395                     2C-window-width)))
 396     ; if other buffer has a local width, adjust here too
 397     (if b1 (setq 2C-window-width (- (frame-width) b1)))
 398     (2C-two-columns b2)))
 399
 400
 401
 402 ;;;###autoload
 403 (defun 2C-split (arg)
 404   "Split a two-column text at point, into two buffers in two-column minor mode.
 405 Point becomes the local value of `2C-window-width'.  Only lines that
 406 have the ARG same preceding characters at that column get split.  The
 407 ARG preceding characters without any leading whitespace become the local
 408 value for `2C-separator'.  This way lines that continue across both
 409 columns remain untouched in the first buffer.
 410
 411 This function can be used with a prototype line, to set up things.  You
 412 write the first line of each column and then split that line.  E.g.:
 413
 414 First column's text    sSs  Second column's text
 415                        \\___/\\
 416                         /    \\
 417    5 character Separator      You type  M-5 \\[2C-split]  with the point here.
 418
 419 \(See  \\[describe-mode] .)"
 420   (interactive "*p")
 421   (and (2C-other)
 422        (if (y-or-n-p (concat "Overwrite associated buffer `"
 423                              (buffer-name (2C-other))
 424                              "'? "))
 425            (save-excursion
 426              (set-buffer (2C-other))
 427              (erase-buffer))
 428          (signal 'quit nil)))
 429   (let ((point (point))
 430         ; make next-line always come back to same column
 431         (goal-column (current-column))
 432         ; a counter for empty lines in other buffer
 433         (n (1- (count-lines (point-min) (point))))
 434         chars other)
 435     (save-excursion
 436       (backward-char arg)
 437       (setq chars (buffer-substring (point) point))
 438       (skip-chars-forward " \t" point)
 439       (make-local-variable '2C-separator)
 440       (setq 2C-separator (buffer-substring (point) point)
 441             2C-window-width (current-column)))
 442     (2C-two-columns)
 443     (setq other (2C-other))
 444     ; now we're ready to actually split
 445     (save-excursion
 446       (while (not (eobp))
 447         (if (not (and (= (current-column) goal-column)
 448                       (string= chars
 449                                (buffer-substring (point)
 450                                                  (save-excursion
 451                                                    (backward-char arg)
 452                                                    (point))))))
 453             (setq n (1+ n))
 454           (setq point (point))
 455           (backward-char arg)
 456           (skip-chars-backward " \t")
 457           (delete-region point (point))
 458           (setq point (point))
 459           (insert-char ?\n n)
 460           (append-to-buffer other point (progn (end-of-line)
 461                                                (if (eobp)
 462                                                    (point)
 463                                                  (1+ (point)))))
 464           (delete-region point (point))
 465           (setq n 0))
 466         (forward-line 1)))))
 467
 468
 469
 470
 471 (defun 2C-dissociate ()
 472   "Turn off two-column minor mode in current and associated buffer.
 473 If the associated buffer is unmodified and empty, it is killed."
 474   (interactive)
 475   (let ((buffer (current-buffer)))
 476     (save-excursion
 477       (and (2C-other)
 478            (set-buffer (2C-other))
 479            (or (not (2C-other))
 480                (eq buffer (2C-other)))
 481            (if (and (not (buffer-modified-p))
 482                     (eobp) (bobp))
 483                (kill-buffer nil)
 484              (kill-local-variable '2C-mode)
 485              (kill-local-variable '2C-window-width)
 486              (kill-local-variable '2C-separator)
 487              (kill-local-variable 'mode-line-format)
 488              (kill-local-variable 'fill-column))))
 489     (kill-local-variable '2C-mode)
 490     (kill-local-variable '2C-window-width)
 491     (kill-local-variable '2C-separator)
 492     (kill-local-variable 'mode-line-format)
 493     (kill-local-variable 'fill-column)))
 494
 495
 496
 497 ;; this doesn't use yank-rectangle, so that the first column can
 498 ;; contain long lines
 499 (defun 2C-merge ()
 500   "Merges the associated buffer with the current buffer.
 501 They get merged at the column, which is the value of `2C-window-width',
 502 i.e. usually at the vertical window separator.  This separator gets
 503 replaced with white space.  Beyond that the value of `2C-separator' gets
 504 inserted on merged lines.  The two columns are thus pasted side by side,
 505 in a single text.  If the other buffer is not displayed to the left of
 506 this one, then this one becomes the left column.
 507
 508 If you want `2C-separator' on empty lines in the second column,
 509 you should put just one space in them.  In the final result, you can strip
 510 off trailing spaces with \\[delete-trailing-whitespace]."
 511   (interactive)
 512   (and (> (car (window-edges)) 0)       ; not touching left edge of screen
 513        (eq (window-buffer (previous-window))
 514            (2C-other t))
 515        (other-window -1))
 516   (save-excursion
 517     (let ((b1 (current-buffer))
 518           (b2 (2C-other t))
 519           string)
 520       (goto-char (point-min))
 521       (set-buffer b2)
 522       (goto-char (point-min))
 523       (while (not (eobp))
 524         (setq string (buffer-substring (point)
 525                                        (progn (end-of-line) (point))))
 526         (or (eobp)
 527             (forward-char))             ; next line
 528         (set-buffer b1)
 529         (if (string= string "")
 530             ()
 531           (end-of-line)
 532           (indent-to-column 2C-window-width)
 533           (insert 2C-separator string))
 534         (forward-line 1)                ; add one if necessary
 535         (set-buffer b2))))
 536   (unless (window-full-width-p)
 537     (enlarge-window 99999 t)))
 538 \f
 539 ;;;;; utility functions ;;;;;
 540
 541 (defun 2C-associated-buffer ()
 542   "Switch to associated buffer."
 543   (interactive)
 544   (let ((line (+ (count-lines (point-min) (point))
 545                  (if (bolp) 1 0)))
 546         (col (if (eolp) (if (bolp) 0) (current-column))))
 547     (if (get-buffer-window (2C-other t))
 548         (select-window (get-buffer-window (2C-other)))
 549       (switch-to-buffer (2C-other)))
 550     (newline (goto-line line))
 551     (if col
 552         (move-to-column col)
 553       (end-of-line 1))))
 554
 555 (defun 2C-newline (arg)
 556   "Insert ARG newlines in both buffers."
 557   (interactive "P")
 558   (save-window-excursion
 559     (2C-associated-buffer)
 560     (newline arg))
 561   (newline arg))
 562
 563 (defun 2C-toggle-autoscroll (arg)
 564   "Toggle autoscrolling.
 565 With prefix argument ARG, turn on autoscrolling if ARG is
 566 positive, otherwise turn it off.  When autoscrolling is turned
 567 on, this also realigns the two buffers."
 568   (interactive "P")
 569   ;(sit-for 0)
 570   (setq 2C-autoscroll-start (window-start))
 571   (if (setq 2C-autoscroll (if arg
 572                               (>= (prefix-numeric-value arg) 0)
 573                             (not 2C-autoscroll)))
 574       (select-window
 575        (prog1 (selected-window)
 576          (message "Autoscrolling is on.")
 577          (setq arg (count-lines (point-min) (window-start)))
 578          (if (get-buffer-window (2C-other t))
 579              (progn
 580                (select-window (get-buffer-window (2C-other)))
 581                (setq arg (- arg (count-lines (point-min) (window-start))))
 582                ;; make sure that other buffer has enough lines
 583                (save-excursion
 584                  (insert-char ?\n
 585                               (- arg (count-lines (window-start)
 586                                                   (goto-char (point-max)))
 587                                  -1)))
 588                (scroll-up arg)))))
 589     (message "Autoscrolling is off.")))
 590
 591
 592
 593 (defun 2C-autoscroll ()
 594   (if 2C-autoscroll
 595       ;; catch a mouse scroll on non-selected scrollbar
 596       (select-window
 597        (prog1 (selected-window)
 598          (and (consp last-command-char)
 599               (not (eq (selected-window)
 600                        (car (car (cdr last-command-char)))))
 601               (select-window (car (car (cdr last-command-char)))))
 602          ;; In some cases scrolling causes an error, but post-command-hook
 603          ;; shouldn't, and should always stay in the original window
 604          (condition-case ()
 605              (and (or 2C-autoscroll-start (2C-toggle-autoscroll t) nil)
 606                   (/= (window-start) 2C-autoscroll-start)
 607                   (2C-other)
 608                   (get-buffer-window (2C-other))
 609                   (let ((lines (count-lines (window-start)
 610                                             2C-autoscroll-start)))
 611                     (if (< (window-start) 2C-autoscroll-start)
 612                         (setq lines (- lines)))
 613                     (setq 2C-autoscroll-start (window-start))
 614                     (select-window (get-buffer-window (2C-other)))
 615                     ;; make sure that other buffer has enough lines
 616                     (save-excursion
 617                       (insert-char
 618                        ?\n (- lines (count-lines (window-start)
 619                                                  (goto-char (point-max)))
 620                               -1)))
 621                     (scroll-up lines)
 622                     (setq 2C-autoscroll-start (window-start))))
 623            (error))))))
 624
 625
 626
 627 (defun 2C-enlarge-window-horizontally (arg)
 628   "Make current window ARG columns wider."
 629   (interactive "p")
 630   (enlarge-window arg t)
 631   (and (2C-other)
 632        (setq 2C-window-width (+ 2C-window-width arg))
 633        (set-buffer (2C-other))
 634        (setq 2C-window-width (- 2C-window-width arg))))
 635
 636 (defun 2C-shrink-window-horizontally (arg)
 637   "Make current window ARG columns narrower."
 638   (interactive "p")
 639   (2C-enlarge-window-horizontally (- arg)))
 640
 641
 642
 643 (provide 'two-column)
 644
 645 ;; arch-tag: 2021b5ab-d3a4-4a8c-a21c-1936b0f9e6b1
 646 ;;; two-column.el ends here