(defgroup longlines nil
"Automatic wrapping of long lines when loading files."
:group 'fill)
(defcustom longlines-auto-wrap t
"Non-nil means long lines are automatically wrapped after each command.
Otherwise, you can perform filling using `fill-paragraph' or
`auto-fill-mode'. In any case, the soft newlines will be removed
when the file is saved to disk."
:group 'longlines
:type 'boolean)
(defcustom longlines-wrap-follows-window-size nil
"Non-nil means wrapping and filling happen at the edge of the window.
Otherwise, `fill-column' is used, regardless of the window size. This
does not work well when the buffer is displayed in multiple windows
with differing widths."
:group 'longlines
:type 'boolean)
(defcustom longlines-show-hard-newlines nil
"Non-nil means each hard newline is marked on the screen.
\(The variable `longlines-show-effect' controls what they look like.)
You can also enable the display temporarily, using the command
`longlines-show-hard-newlines'."
:group 'longlines
:type 'boolean)
(defcustom longlines-show-effect (propertize "|\n" 'face 'escape-glyph)
"A string to display when showing hard newlines.
This is used when `longlines-show-hard-newlines' is on."
:group 'longlines
:type 'string)
(defvar longlines-wrap-beg nil)
(defvar longlines-wrap-end nil)
(defvar longlines-wrap-point nil)
(defvar longlines-showing nil)
(make-variable-buffer-local 'longlines-wrap-beg)
(make-variable-buffer-local 'longlines-wrap-end)
(make-variable-buffer-local 'longlines-wrap-point)
(make-variable-buffer-local 'longlines-showing)
(define-minor-mode longlines-mode
"Toggle Long Lines mode.
In Long Lines mode, long lines are wrapped if they extend beyond
`fill-column'. The soft newlines used for line wrapping will not
show up when the text is yanked or saved to disk.
If the variable `longlines-auto-wrap' is non-nil, lines are automatically
wrapped whenever the buffer is changed. You can always call
`fill-paragraph' to fill individual paragraphs.
If the variable `longlines-show-hard-newlines' is non-nil, hard newlines
are indicated with a symbol."
:group 'longlines :lighter " ll"
(if longlines-mode
(progn
(use-hard-newlines 1 'never)
(set (make-local-variable 'require-final-newline) nil)
(add-to-list 'buffer-file-format 'longlines)
(add-hook 'change-major-mode-hook 'longlines-mode-off nil t)
(add-hook 'before-revert-hook 'longlines-before-revert-hook nil t)
(make-local-variable 'buffer-substring-filters)
(set (make-local-variable 'isearch-search-fun-function)
'longlines-search-function)
(add-to-list 'buffer-substring-filters 'longlines-encode-string)
(when longlines-wrap-follows-window-size
(set (make-local-variable 'fill-column)
(- (window-width) window-min-width))
(add-hook 'window-configuration-change-hook
'longlines-window-change-function nil t))
(let ((buffer-undo-list t)
(inhibit-read-only t)
(after-change-functions nil)
(mod (buffer-modified-p)))
(save-restriction
(widen)
(longlines-decode-buffer)
(longlines-wrap-region (point-min) (point-max)))
(set-buffer-modified-p mod))
(when (and longlines-show-hard-newlines
(not longlines-showing))
(longlines-show-hard-newlines))
(cond ((eq major-mode 'mail-mode)
(add-hook 'mail-setup-hook 'longlines-decode-buffer nil t)
(or mail-citation-hook
(add-hook 'mail-citation-hook 'mail-indent-citation nil t))
(add-hook 'mail-citation-hook 'longlines-decode-region nil t))
((eq major-mode 'message-mode)
(add-hook 'message-setup-hook 'longlines-decode-buffer nil t)
(make-local-variable 'message-indent-citation-function)
(if (not (listp message-indent-citation-function))
(setq message-indent-citation-function
(list message-indent-citation-function)))
(add-to-list 'message-indent-citation-function
'longlines-decode-region t)))
(when longlines-auto-wrap
(auto-fill-mode 0)
(add-hook 'after-change-functions
'longlines-after-change-function nil t)
(add-hook 'post-command-hook
'longlines-post-command-function nil t)))
(setq buffer-file-format (delete 'longlines buffer-file-format))
(if longlines-showing
(longlines-unshow-hard-newlines))
(let ((buffer-undo-list t)
(after-change-functions nil)
(inhibit-read-only t))
(save-restriction
(widen)
(longlines-encode-region (point-min) (point-max))))
(remove-hook 'change-major-mode-hook 'longlines-mode-off t)
(remove-hook 'after-change-functions 'longlines-after-change-function t)
(remove-hook 'post-command-hook 'longlines-post-command-function t)
(remove-hook 'before-revert-hook 'longlines-before-revert-hook t)
(remove-hook 'window-configuration-change-hook
'longlines-window-change-function t)
(when longlines-wrap-follows-window-size
(kill-local-variable 'fill-column))
(kill-local-variable 'isearch-search-fun-function)
(kill-local-variable 'require-final-newline)
(kill-local-variable 'buffer-substring-filters)
(kill-local-variable 'use-hard-newlines)))
(defun longlines-mode-off ()
"Turn off longlines mode.
This function exists to be called by `change-major-mode-hook' when the
major mode changes."
(longlines-mode 0))
(defun longlines-show-hard-newlines (&optional arg)
"Make hard newlines visible by adding a face.
With optional argument ARG, make the hard newlines invisible again."
(interactive "P")
(let ((buffer-undo-list t)
(mod (buffer-modified-p)))
(if arg
(longlines-unshow-hard-newlines)
(setq longlines-showing t)
(longlines-show-region (point-min) (point-max)))
(set-buffer-modified-p mod)))
(defun longlines-show-region (beg end)
"Make hard newlines between BEG and END visible."
(let* ((pmin (min beg end))
(pmax (max beg end))
(pos (text-property-not-all pmin pmax 'hard nil))
(inhibit-read-only t))
(while pos
(put-text-property pos (1+ pos) 'display
(copy-sequence longlines-show-effect))
(setq pos (text-property-not-all (1+ pos) pmax 'hard nil)))))
(defun longlines-unshow-hard-newlines ()
"Make hard newlines invisible again."
(interactive)
(setq longlines-showing nil)
(let ((pos (text-property-not-all (point-min) (point-max) 'hard nil)))
(while pos
(remove-text-properties pos (1+ pos) '(display))
(setq pos (text-property-not-all (1+ pos) (point-max) 'hard nil)))))
(defun longlines-wrap-region (beg end)
"Wrap each successive line, starting with the line before BEG.
Stop when we reach lines after END that don't need wrapping, or the
end of the buffer."
(setq longlines-wrap-point (point))
(goto-char beg)
(forward-line -1)
(while (null (and (longlines-wrap-line)
(or (eobp)
(and (>= (point) end)
(longlines-wrap-line))))))
(goto-char longlines-wrap-point))
(defun longlines-wrap-line ()
"If the current line needs to be wrapped, wrap it and return nil.
If wrapping is performed, point remains on the line. If the line does
not need to be wrapped, move point to the next line and return t."
(if (longlines-set-breakpoint)
(progn (insert-before-markers ?\n)
(backward-char 1)
(delete-char -1)
(forward-char 1)
nil)
(if (longlines-merge-lines-p)
(progn (end-of-line)
(if (or (prog1 (bolp) (forward-char 1)) (eolp))
(progn
(delete-char -1)
(if (> longlines-wrap-point (point))
(setq longlines-wrap-point
(1- longlines-wrap-point))))
(insert-before-markers-and-inherit ?\s)
(backward-char 1)
(delete-char -1)
(forward-char 1))
nil)
(forward-line 1)
t)))
(defun longlines-set-breakpoint ()
"Place point where we should break the current line, and return t.
If the line should not be broken, return nil; point remains on the
line."
(move-to-column fill-column)
(if (and (re-search-forward "[^ ]" (line-end-position) 1)
(> (current-column) fill-column))
(or (longlines-find-break-backward)
(progn (move-to-column fill-column)
(longlines-find-break-forward)))))
(defun longlines-find-break-backward ()
"Move point backward to the first available breakpoint and return t.
If no breakpoint is found, return nil."
(and (search-backward " " (line-beginning-position) 1)
(save-excursion
(skip-chars-backward " " (line-beginning-position))
(null (bolp)))
(progn (forward-char 1)
(if (and fill-nobreak-predicate
(run-hook-with-args-until-success
'fill-nobreak-predicate))
(progn (skip-chars-backward " " (line-beginning-position))
(longlines-find-break-backward))
t))))
(defun longlines-find-break-forward ()
"Move point forward to the first available breakpoint and return t.
If no break point is found, return nil."
(and (search-forward " " (line-end-position) 1)
(progn (skip-chars-forward " " (line-end-position))
(null (eolp)))
(if (and fill-nobreak-predicate
(run-hook-with-args-until-success
'fill-nobreak-predicate))
(longlines-find-break-forward)
t)))
(defun longlines-merge-lines-p ()
"Return t if part of the next line can fit onto the current line.
Otherwise, return nil. Text cannot be moved across hard newlines."
(save-excursion
(end-of-line)
(and (null (eobp))
(null (get-text-property (point) 'hard))
(let ((space (- fill-column (current-column))))
(forward-line 1)
(if (eq (char-after) ? )
t (<= (if (search-forward " " (line-end-position) 1)
(current-column)
(1+ (current-column)))
space))))))
(defun longlines-decode-region (&optional beg end)
"Turn all newlines between BEG and END into hard newlines.
If BEG and END are nil, the point and mark are used."
(if (null beg) (setq beg (point)))
(if (null end) (setq end (mark t)))
(save-excursion
(let ((reg-max (max beg end)))
(goto-char (min beg end))
(while (search-forward "\n" reg-max t)
(set-hard-newline-properties
(match-beginning 0) (match-end 0))))))
(defun longlines-decode-buffer ()
"Turn all newlines in the buffer into hard newlines."
(longlines-decode-region (point-min) (point-max)))
(defun longlines-encode-region (beg end &optional buffer)
"Replace each soft newline between BEG and END with exactly one space.
Hard newlines are left intact. The optional argument BUFFER exists for
compatibility with `format-alist', and is ignored."
(save-excursion
(let ((reg-max (max beg end))
(mod (buffer-modified-p)))
(goto-char (min beg end))
(while (search-forward "\n" reg-max t)
(unless (get-text-property (match-beginning 0) 'hard)
(replace-match " ")))
(set-buffer-modified-p mod)
end)))
(defun longlines-encode-string (string)
"Return a copy of STRING with each soft newline replaced by a space.
Hard newlines are left intact."
(let* ((str (copy-sequence string))
(pos (string-match "\n" str)))
(while pos
(if (null (get-text-property pos 'hard str))
(aset str pos ? ))
(setq pos (string-match "\n" str (1+ pos))))
str))
(defun longlines-auto-wrap (&optional arg)
"Turn on automatic line wrapping, and wrap the entire buffer.
With optional argument ARG, turn off line wrapping."
(interactive "P")
(remove-hook 'after-change-functions 'longlines-after-change-function t)
(remove-hook 'post-command-hook 'longlines-post-command-function t)
(if arg
(progn (setq longlines-auto-wrap nil)
(message "Auto wrap disabled."))
(setq longlines-auto-wrap t)
(add-hook 'after-change-functions
'longlines-after-change-function nil t)
(add-hook 'post-command-hook
'longlines-post-command-function nil t)
(let ((mod (buffer-modified-p)))
(longlines-wrap-region (point-min) (point-max))
(set-buffer-modified-p mod))
(message "Auto wrap enabled.")))
(defun longlines-after-change-function (beg end len)
"Update `longlines-wrap-beg' and `longlines-wrap-end'.
This is called by `after-change-functions' to keep track of the region
that has changed."
(unless undo-in-progress
(setq longlines-wrap-beg
(if longlines-wrap-beg (min longlines-wrap-beg beg) beg))
(setq longlines-wrap-end
(if longlines-wrap-end (max longlines-wrap-end end) end))))
(defun longlines-post-command-function ()
"Perform line wrapping on the parts of the buffer that have changed.
This is called by `post-command-hook' after each command."
(when longlines-wrap-beg
(if (or (eq this-command 'yank)
(eq this-command 'yank-pop))
(longlines-decode-region (point) (mark t)))
(if longlines-showing
(longlines-show-region longlines-wrap-beg longlines-wrap-end))
(unless (or (eq this-command 'fill-paragraph)
(eq this-command 'fill-region))
(longlines-wrap-region longlines-wrap-beg longlines-wrap-end))
(setq longlines-wrap-beg nil)
(setq longlines-wrap-end nil)))
(defun longlines-window-change-function ()
"Re-wrap the buffer if the window width has changed.
This is called by `window-configuration-change-hook'."
(when (/= fill-column (- (window-width) window-min-width))
(setq fill-column (- (window-width) window-min-width))
(let ((mod (buffer-modified-p)))
(longlines-wrap-region (point-min) (point-max))
(set-buffer-modified-p mod))))
(defun longlines-search-function ()
(cond
(isearch-word
(if isearch-forward 'word-search-forward 'word-search-backward))
(isearch-regexp
(if isearch-forward 're-search-forward 're-search-backward))
(t
(if isearch-forward
'longlines-search-forward
'longlines-search-backward))))
(defun longlines-search-forward (string &optional bound noerror count)
(let ((search-spaces-regexp "[ \n]+"))
(re-search-forward (regexp-quote string) bound noerror count)))
(defun longlines-search-backward (string &optional bound noerror count)
(let ((search-spaces-regexp "[ \n]+"))
(re-search-backward (regexp-quote string) bound noerror count)))
(defun longlines-before-revert-hook ()
(add-hook 'after-revert-hook 'longlines-after-revert-hook nil t)
(longlines-mode 0))
(defun longlines-after-revert-hook ()
(remove-hook 'after-revert-hook 'longlines-after-revert-hook t)
(longlines-mode 1))
(add-to-list
'format-alist
(list 'longlines "Automatically wrap long lines." nil nil
'longlines-encode-region t nil))
(provide 'longlines)