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395 lines
15 KiB
EmacsLisp
395 lines
15 KiB
EmacsLisp
;;; longlines.el --- automatically wrap long lines
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;; Copyright (C) 2000, 2001, 2005 Free Software Foundation, Inc.
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;; Authors: Kai Grossjohann <Kai.Grossjohann@CS.Uni-Dortmund.DE>
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;; Alex Schroeder <alex@gnu.org>
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;; Chong Yidong <cyd@stupidchicken.com>
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;; Maintainer: Chong Yidong <cyd@stupidchicken.com>
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;; Keywords: convenience
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software; you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation; either version 2, or (at your option)
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;; any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs; see the file COPYING. If not, write to the
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;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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;; Boston, MA 02110-1301, USA.
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;;; Commentary:
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;; Some text editors save text files with long lines, and they
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;; automatically break these lines at whitespace, without actually
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;; inserting any newline characters. When doing `M-q' in Emacs, you
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;; are inserting newline characters. Longlines mode provides a file
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;; format which wraps the long lines when reading a file and unwraps
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;; the lines when saving the file. It can also wrap and unwrap
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;; automatically as editing takes place.
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;; Special thanks to Rod Smith for many useful bug reports.
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;;; Code:
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(defgroup longlines nil
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"Automatic wrapping of long lines when loading files."
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:group 'fill)
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(defcustom longlines-auto-wrap t
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"*Non-nil means long lines are automatically wrapped after each command.
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Otherwise, you can perform filling using `fill-paragraph' or
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`auto-fill-mode'. In any case, the soft newlines will be removed
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when the file is saved to disk."
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:group 'longlines
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:type 'boolean)
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(defcustom longlines-wrap-follows-window-size nil
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"*Non-nil means wrapping and filling happen at the edge of the window.
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Otherwise, `fill-column' is used, regardless of the window size. This
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does not work well when the buffer is displayed in multiple windows
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with differing widths."
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:group 'longlines
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:type 'boolean)
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(defcustom longlines-show-hard-newlines nil
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"*Non-nil means each hard newline is marked on the screen.
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\(The variable `longlines-show-effect' controls what they look like.)
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You can also enable the display temporarily, using the command
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`longlines-show-hard-newlines'"
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:group 'longlines
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:type 'boolean)
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(defcustom longlines-show-effect (propertize "|\n" 'face 'escape-glyph)
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"*A string to display when showing hard newlines.
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This is used when `longlines-show-hard-newlines' is on."
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:group 'longlines
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:type 'string)
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;; Internal variables
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(defvar longlines-wrap-beg nil)
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(defvar longlines-wrap-end nil)
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(defvar longlines-wrap-point nil)
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(defvar longlines-showing nil)
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(make-variable-buffer-local 'longlines-wrap-beg)
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(make-variable-buffer-local 'longlines-wrap-end)
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(make-variable-buffer-local 'longlines-wrap-point)
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(make-variable-buffer-local 'longlines-showing)
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;; Mode
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;;;###autoload
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(define-minor-mode longlines-mode
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"Toggle Long Lines mode.
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In Long Lines mode, long lines are wrapped if they extend beyond
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`fill-column'. The soft newlines used for line wrapping will not
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show up when the text is yanked or saved to disk.
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If the variable `longlines-auto-wrap' is non-nil, lines are automatically
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wrapped whenever the buffer is changed. You can always call
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`fill-paragraph' to fill individual paragraphs.
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If the variable `longlines-show-hard-newlines' is non-nil, hard newlines
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are indicated with a symbol."
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:group 'longlines :lighter " ll"
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(if longlines-mode
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;; Turn on longlines mode
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(progn
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(use-hard-newlines 1 'never)
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(set (make-local-variable 'require-final-newline) nil)
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(add-to-list 'buffer-file-format 'longlines)
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(add-hook 'change-major-mode-hook 'longlines-mode-off nil t)
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(make-local-variable 'buffer-substring-filters)
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(add-to-list 'buffer-substring-filters 'longlines-encode-string)
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(when longlines-wrap-follows-window-size
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(set (make-local-variable 'fill-column)
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(- (window-width) window-min-width))
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(add-hook 'window-configuration-change-hook
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'longlines-window-change-function nil t))
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(let ((buffer-undo-list t)
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(inhibit-read-only t)
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(mod (buffer-modified-p)))
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;; Turning off undo is OK since (spaces + newlines) is
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;; conserved, except for a corner case in
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;; longlines-wrap-lines that we'll never encounter from here
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(longlines-decode-region (point-min) (point-max))
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(longlines-wrap-region (point-min) (point-max))
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(set-buffer-modified-p mod))
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(when (and longlines-show-hard-newlines
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(not longlines-showing))
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(longlines-show-hard-newlines))
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(when longlines-auto-wrap
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(auto-fill-mode 0)
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(add-hook 'after-change-functions
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'longlines-after-change-function nil t)
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(add-hook 'post-command-hook
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'longlines-post-command-function nil t)))
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;; Turn off longlines mode
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(setq buffer-file-format (delete 'longlines buffer-file-format))
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(if longlines-showing
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(longlines-unshow-hard-newlines))
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(let ((buffer-undo-list t)
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(inhibit-read-only t))
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(longlines-encode-region (point-min) (point-max)))
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(remove-hook 'change-major-mode-hook 'longlines-mode-off t)
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(remove-hook 'before-kill-functions 'longlines-encode-region t)
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(remove-hook 'after-change-functions 'longlines-after-change-function t)
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(remove-hook 'post-command-hook 'longlines-post-command-function t)
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(remove-hook 'window-configuration-change-hook
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'longlines-window-change-function t)
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(when longlines-wrap-follows-window-size
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(kill-local-variable 'fill-column))
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(kill-local-variable 'require-final-newline)
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(kill-local-variable 'buffer-substring-filters)
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(kill-local-variable 'use-hard-newlines)))
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(defun longlines-mode-off ()
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"Turn off longlines mode.
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This function exists to be called by `change-major-mode-hook' when the
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major mode changes."
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(longlines-mode 0))
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;; Showing the effect of hard newlines in the buffer
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(defun longlines-show-hard-newlines (&optional arg)
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"Make hard newlines visible by adding a face.
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With optional argument ARG, make the hard newlines invisible again."
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(interactive "P")
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(let ((buffer-undo-list t)
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(mod (buffer-modified-p)))
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(if arg
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(longlines-unshow-hard-newlines)
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(setq longlines-showing t)
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(longlines-show-region (point-min) (point-max)))
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(set-buffer-modified-p mod)))
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(defun longlines-show-region (beg end)
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"Make hard newlines between BEG and END visible."
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(let* ((pmin (min beg end))
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(pmax (max beg end))
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(pos (text-property-not-all pmin pmax 'hard nil)))
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(while pos
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(put-text-property pos (1+ pos) 'display
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(copy-sequence longlines-show-effect))
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(setq pos (text-property-not-all (1+ pos) pmax 'hard nil)))))
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(defun longlines-unshow-hard-newlines ()
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"Make hard newlines invisible again."
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(interactive)
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(setq longlines-showing nil)
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(let ((pos (text-property-not-all (point-min) (point-max) 'hard nil)))
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(while pos
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(remove-text-properties pos (1+ pos) '(display))
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(setq pos (text-property-not-all (1+ pos) (point-max) 'hard nil)))))
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;; Wrapping the paragraphs.
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(defun longlines-wrap-region (beg end)
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"Wrap each successive line, starting with the line before BEG.
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Stop when we reach lines after END that don't need wrapping, or the
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end of the buffer."
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(setq longlines-wrap-point (point))
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(goto-char beg)
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(forward-line -1)
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;; Two successful longlines-wrap-line's in a row mean successive
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;; lines don't need wrapping.
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(while (null (and (longlines-wrap-line)
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(or (eobp)
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(and (>= (point) end)
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(longlines-wrap-line))))))
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(goto-char longlines-wrap-point))
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(defun longlines-wrap-line ()
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"If the current line needs to be wrapped, wrap it and return nil.
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If wrapping is performed, point remains on the line. If the line does
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not need to be wrapped, move point to the next line and return t."
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(if (longlines-set-breakpoint)
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(progn (backward-char 1)
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(delete-char 1)
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(insert-char ?\n 1)
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nil)
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(if (longlines-merge-lines-p)
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(progn (end-of-line)
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(delete-char 1)
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;; After certain commands (e.g. kill-line), there may be two
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;; successive soft newlines in the buffer. In this case, we
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;; replace these two newlines by a single space. Unfortunately,
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;; this breaks the conservation of (spaces + newlines), so we
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;; have to fiddle with longlines-wrap-point.
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(if (or (bolp) (eolp))
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(if (> longlines-wrap-point (point))
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(setq longlines-wrap-point
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(1- longlines-wrap-point)))
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(insert-char ? 1))
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nil)
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(forward-line 1)
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t)))
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(defun longlines-set-breakpoint ()
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"Place point where we should break the current line, and return t.
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If the line should not be broken, return nil; point remains on the
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line."
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(move-to-column fill-column)
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(if (and (re-search-forward "[^ ]" (line-end-position) 1)
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(> (current-column) fill-column))
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;; This line is too long. Can we break it?
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(or (longlines-find-break-backward)
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(progn (move-to-column fill-column)
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(longlines-find-break-forward)))))
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(defun longlines-find-break-backward ()
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"Move point backward to the first available breakpoint and return t.
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If no breakpoint is found, return nil."
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(and (search-backward " " (line-beginning-position) 1)
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(save-excursion
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(skip-chars-backward " " (line-beginning-position))
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(null (bolp)))
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(progn (forward-char 1)
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(if (and fill-nobreak-predicate
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(run-hook-with-args-until-success
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'fill-nobreak-predicate))
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(progn (skip-chars-backward " " (line-beginning-position))
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(longlines-find-break-backward))
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t))))
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(defun longlines-find-break-forward ()
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"Move point forward to the first available breakpoint and return t.
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If no break point is found, return nil."
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(and (search-forward " " (line-end-position) 1)
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(progn (skip-chars-forward " " (line-end-position))
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(null (eolp)))
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(if (and fill-nobreak-predicate
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(run-hook-with-args-until-success
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'fill-nobreak-predicate))
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(longlines-find-break-forward)
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t)))
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(defun longlines-merge-lines-p ()
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"Return t if part of the next line can fit onto the current line.
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Otherwise, return nil. Text cannot be moved across hard newlines."
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(save-excursion
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(end-of-line)
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(and (null (eobp))
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(null (get-text-property (point) 'hard))
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(let ((space (- fill-column (current-column))))
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(forward-line 1)
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(if (eq (char-after) ? )
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t ; We can always merge some spaces
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(<= (if (search-forward " " (line-end-position) 1)
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(current-column)
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(1+ (current-column)))
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space))))))
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(defun longlines-decode-region (beg end)
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"Turn all newlines between BEG and END into hard newlines."
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(save-excursion
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(goto-char (min beg end))
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(while (search-forward "\n" (max beg end) t)
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(set-hard-newline-properties
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(match-beginning 0) (match-end 0)))))
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(defun longlines-encode-region (beg end &optional buffer)
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"Replace each soft newline between BEG and END with exactly one space.
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Hard newlines are left intact. The optional argument BUFFER exists for
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compatibility with `format-alist', and is ignored."
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(save-excursion
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(let ((mod (buffer-modified-p)))
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(goto-char (min beg end))
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(while (search-forward "\n" (max (max beg end)) t)
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(unless (get-text-property (match-beginning 0) 'hard)
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(replace-match " ")))
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(set-buffer-modified-p mod)
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end)))
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(defun longlines-encode-string (string)
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"Return a copy of STRING with each soft newline replaced by a space.
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Hard newlines are left intact."
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(let* ((str (copy-sequence string))
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(pos (string-match "\n" str)))
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(while pos
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(if (null (get-text-property pos 'hard str))
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(aset str pos ? ))
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(setq pos (string-match "\n" str (1+ pos))))
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str))
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;; Auto wrap
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(defun longlines-auto-wrap (&optional arg)
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"Turn on automatic line wrapping, and wrap the entire buffer.
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With optional argument ARG, turn off line wrapping."
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(interactive "P")
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(remove-hook 'after-change-functions 'longlines-after-change-function t)
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(remove-hook 'post-command-hook 'longlines-post-command-function t)
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(if arg
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(progn (setq longlines-auto-wrap nil)
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(message "Auto wrap disabled."))
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(setq longlines-auto-wrap t)
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(add-hook 'after-change-functions
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'longlines-after-change-function nil t)
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(add-hook 'post-command-hook
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'longlines-post-command-function nil t)
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(let ((mod (buffer-modified-p)))
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(longlines-wrap-region (point-min) (point-max))
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(set-buffer-modified-p mod))
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(message "Auto wrap enabled.")))
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(defun longlines-after-change-function (beg end len)
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"Update `longlines-wrap-beg' and `longlines-wrap-end'.
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This is called by `after-change-functions' to keep track of the region
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that has changed."
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(unless undo-in-progress
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(setq longlines-wrap-beg
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(if longlines-wrap-beg (min longlines-wrap-beg beg) beg))
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(setq longlines-wrap-end
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(if longlines-wrap-end (max longlines-wrap-end end) end))))
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(defun longlines-post-command-function ()
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"Perform line wrapping on the parts of the buffer that have changed.
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This is called by `post-command-hook' after each command."
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(when longlines-wrap-beg
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(cond ((or (eq this-command 'yank)
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(eq this-command 'yank-pop))
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(longlines-decode-region (point) (mark t))
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(if longlines-showing
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(longlines-show-region (point) (mark t))))
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((and (eq this-command 'newline) longlines-showing)
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(save-excursion
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(if (search-backward "\n" nil t)
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(longlines-show-region
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(match-beginning 0) (match-end 0))))))
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(unless (or (eq this-command 'fill-paragraph)
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(eq this-command 'fill-region))
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(longlines-wrap-region longlines-wrap-beg longlines-wrap-end))
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(setq longlines-wrap-beg nil)
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(setq longlines-wrap-end nil)))
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(defun longlines-window-change-function ()
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"Re-wrap the buffer if the window width has changed.
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This is called by `window-size-change-functions'."
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(when (/= fill-column (- (window-width) window-min-width))
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(setq fill-column (- (window-width) window-min-width))
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(let ((mod (buffer-modified-p)))
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(longlines-wrap-region (point-min) (point-max))
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(set-buffer-modified-p mod))))
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;; Loading and saving
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(add-to-list
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'format-alist
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(list 'longlines "Automatically wrap long lines." nil
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'longlines-decode-region 'longlines-encode-region t nil))
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(provide 'longlines)
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;; arch-tag: 3489d225-5506-47b9-8659-d8807b77c624
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;;; longlines.el ends here
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