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emacs/lisp/textmodes/fill.el
Richard M. Stallman 89cd98f3ef (fill-paragraph): Don't actually change point before
calling fill-region-as-paragraph.
(fill-region-as-paragraph): Save point on undo list at start.
1992-10-04 04:10:02 +00:00

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;;; fill.el --- fill commands for Emacs
;; Copyright (C) 1985, 1986, 1992 Free Software Foundation, Inc.
;; Keywords: wp
;; This file is part of GNU Emacs.
;; GNU Emacs is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2, or (at your option)
;; any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING. If not, write to
;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
;;; Code:
(defconst fill-individual-varying-indent nil
"*Controls criterion for a new paragraph in `fill-individual-paragraphs'.
Non-nil means changing indent doesn't end a paragraph.
That mode can handle paragraphs with extra indentation on the first line,
but it requires separator lines between paragraphs.
Nil means that any change in indentation starts a new paragraph.")
(defun set-fill-prefix ()
"Set the fill-prefix to the current line up to point.
Filling expects lines to start with the fill prefix and
reinserts the fill prefix in each resulting line."
(interactive)
(setq fill-prefix (buffer-substring
(save-excursion (beginning-of-line) (point))
(point)))
(if (equal fill-prefix "")
(setq fill-prefix nil))
(if fill-prefix
(message "fill-prefix: \"%s\"" fill-prefix)
(message "fill-prefix cancelled")))
(defconst adaptive-fill-mode t
"*Non-nil means determine a paragraph's fill prefix from its text.")
(defconst adaptive-fill-regexp "[ \t]*\\([>*] +\\)?"
"*Regexp to match text at start of line that constitutes indentation.
If Adaptive Fill mode is enabled, whatever text matches this pattern
on the second line of a paragraph is used as the standard indentation
for the paragraph.")
(defun fill-region-as-paragraph (from to &optional justify-flag)
"Fill region as one paragraph: break lines to fit fill-column.
Prefix arg means justify too.
From program, pass args FROM, TO and JUSTIFY-FLAG."
(interactive "r\nP")
;; Arrange for undoing the fill to restore point.
(if (and buffer-undo-list (not (eq buffer-undo-list t)))
(setq buffer-undo-list (cons (point) buffer-undo-list)))
;; Don't let Adaptive Fill mode alter the fill prefix permanently.
(let ((fill-prefix fill-prefix))
;; Figure out how this paragraph is indented, if desired.
(if (and adaptive-fill-mode
(or (null fill-prefix) (string= fill-prefix "")))
(save-excursion
(goto-char (min from to))
(if (eolp) (forward-line 1))
(forward-line 1)
(if (< (point) (max from to))
(let ((start (point)))
(re-search-forward adaptive-fill-regexp)
(setq fill-prefix (buffer-substring start (point))))
(goto-char (min from to))
(if (eolp) (forward-line 1))
;; If paragraph has only one line, don't assume
;; that additional lines would have the same starting
;; decoration. Assume no indentation.
;; (re-search-forward adaptive-fill-regexp)
;; (setq fill-prefix (make-string (current-column) ?\ ))
)))
(save-restriction
(narrow-to-region from to)
(goto-char (point-min))
(skip-chars-forward "\n")
(narrow-to-region (point) (point-max))
(setq from (point))
(goto-char (point-max))
(let ((fpre (and fill-prefix (not (equal fill-prefix ""))
(regexp-quote fill-prefix))))
;; Delete the fill prefix from every line except the first.
;; The first line may not even have a fill prefix.
(and fpre
(progn
(if (>= (length fill-prefix) fill-column)
(error "fill-prefix too long for specified width"))
(goto-char (point-min))
(forward-line 1)
(while (not (eobp))
(if (looking-at fpre)
(delete-region (point) (match-end 0)))
(forward-line 1))
(goto-char (point-min))
(and (looking-at fpre) (forward-char (length fill-prefix)))
(setq from (point)))))
;; from is now before the text to fill,
;; but after any fill prefix on the first line.
;; Make sure sentences ending at end of line get an extra space.
;; loses on split abbrevs ("Mr.\nSmith")
(goto-char from)
(while (re-search-forward "[.?!][])}\"']*$" nil t)
(insert ? ))
;; Then change all newlines to spaces.
(subst-char-in-region from (point-max) ?\n ?\ )
;; Flush excess spaces, except in the paragraph indentation.
(goto-char from)
(skip-chars-forward " \t")
;; nuke tabs while we're at it; they get screwed up in a fill
;; this is quick, but loses when a sole tab follows the end of a sentence.
;; actually, it is difficult to tell that from "Mr.\tSmith".
;; blame the typist.
(subst-char-in-region (point) (point-max) ?\t ?\ )
(while (re-search-forward " *" nil t)
(delete-region
(+ (match-beginning 0)
(if (save-excursion
(skip-chars-backward " ]})\"'")
(memq (preceding-char) '(?. ?? ?!)))
2 1))
(match-end 0)))
(goto-char (point-max))
(delete-horizontal-space)
(insert " ")
(goto-char (point-min))
;; This is the actual filling loop.
(let ((prefixcol 0) linebeg)
(while (not (eobp))
(setq linebeg (point))
(move-to-column (1+ fill-column))
(if (eobp)
nil
;; Move back to start of word.
(skip-chars-backward "^ \n" linebeg)
;; Don't break after a period followed by just one space.
;; Move back to the previous place to break.
;; The reason is that if a period ends up at the end of a line,
;; further fills will assume it ends a sentence.
;; If we now know it does not end a sentence,
;; avoid putting it at the end of the line.
(while (and (> (point) (+ linebeg 2))
(eq (preceding-char) ?\ )
(eq (char-after (- (point) 2)) ?\.))
(forward-char -2)
(skip-chars-backward "^ \n" linebeg))
(if (if (zerop prefixcol) (bolp) (>= prefixcol (current-column)))
;; Keep at least one word even if fill prefix exceeds margin.
;; This handles all but the first line of the paragraph.
(progn
(skip-chars-forward " ")
(skip-chars-forward "^ \n"))
;; Normally, move back over the single space between the words.
(forward-char -1)))
(if (and fill-prefix (zerop prefixcol)
(< (- (point) (point-min)) (length fill-prefix))
(string= (buffer-substring (point-min) (point))
(substring fill-prefix 0 (- (point) (point-min)))))
;; Keep at least one word even if fill prefix exceeds margin.
;; This handles the first line of the paragraph.
(progn
(skip-chars-forward " ")
(skip-chars-forward "^ \n")))
;; Replace all whitespace here with one newline.
;; Insert before deleting, so we don't forget which side of
;; the whitespace point or markers used to be on.
(skip-chars-backward " ")
(insert ?\n)
(delete-horizontal-space)
;; Insert the fill prefix at start of each line.
;; Set prefixcol so whitespace in the prefix won't get lost.
(and (not (eobp)) fill-prefix (not (equal fill-prefix ""))
(progn
(insert fill-prefix)
(setq prefixcol (current-column))))
;; Justify the line just ended, if desired.
(and justify-flag (not (eobp))
(progn
(forward-line -1)
(justify-current-line)
(forward-line 1))))))))
(defun fill-paragraph (arg)
"Fill paragraph at or after point. Prefix arg means justify as well."
(interactive "P")
(let ((before (point)))
(save-excursion
(forward-paragraph)
(or (bolp) (newline 1))
(let ((end (point))
(beg (progn (backward-paragraph) (point))))
(goto-char before)
(fill-region-as-paragraph beg end arg)))))
(defun fill-region (from to &optional justify-flag)
"Fill each of the paragraphs in the region.
Prefix arg (non-nil third arg, if called from program) means justify as well."
(interactive "r\nP")
(save-restriction
(narrow-to-region from to)
(goto-char (point-min))
(while (not (eobp))
(let ((initial (point))
(end (progn
(forward-paragraph 1) (point))))
(forward-paragraph -1)
(if (>= (point) initial)
(fill-region-as-paragraph (point) end justify-flag)
(goto-char end))))))
(defun justify-current-line ()
"Add spaces to line point is in, so it ends at `fill-column'."
(interactive)
(save-excursion
(save-restriction
(let (ncols beg indent)
(beginning-of-line)
(forward-char (length fill-prefix))
(skip-chars-forward " \t")
(setq indent (current-column))
(setq beg (point))
(end-of-line)
(narrow-to-region beg (point))
(goto-char beg)
(while (re-search-forward " *" nil t)
(delete-region
(+ (match-beginning 0)
(if (save-excursion
(skip-chars-backward " ])\"'")
(memq (preceding-char) '(?. ?? ?!)))
2 1))
(match-end 0)))
(goto-char beg)
(while (re-search-forward "[.?!][])\"']*\n" nil t)
(forward-char -1)
(insert ? ))
(goto-char (point-max))
;; Note that the buffer bounds start after the indentation,
;; so the columns counted by INDENT don't appear in (current-column).
(setq ncols (- fill-column (current-column) indent))
(if (search-backward " " nil t)
(while (> ncols 0)
(let ((nmove (+ 3 (random 3))))
(while (> nmove 0)
(or (search-backward " " nil t)
(progn
(goto-char (point-max))
(search-backward " ")))
(skip-chars-backward " ")
(setq nmove (1- nmove))))
(insert " ")
(skip-chars-backward " ")
(setq ncols (1- ncols))))))))
(defun fill-individual-paragraphs (min max &optional justifyp mailp)
"Fill each paragraph in region according to its individual fill prefix.
If `fill-individual-varying-indent' is non-nil,
then a mere change in indentation does not end a paragraph. In this mode,
the indentation for a paragraph is the minimum indentation of any line in it.
When calling from a program, pass range to fill as first two arguments.
Optional third and fourth arguments JUSTIFY-FLAG and MAIL-FLAG:
JUSTIFY-FLAG to justify paragraphs (prefix arg),
MAIL-FLAG for a mail message, i. e. don't fill header lines."
(interactive "r\nP")
(save-restriction
(save-excursion
(goto-char min)
(beginning-of-line)
(if mailp
(while (or (looking-at "[ \t]*[^ \t\n]*:") (looking-at "[ \t]*$"))
(forward-line 1)))
(narrow-to-region (point) max)
;; Loop over paragraphs.
(while (progn (skip-chars-forward " \t\n") (not (eobp)))
(beginning-of-line)
(let ((start (point))
fill-prefix fill-prefix-regexp)
;; Find end of paragraph, and compute the smallest fill-prefix
;; that fits all the lines in this paragraph.
(while (progn
;; Update the fill-prefix on the first line
;; and whenever the prefix good so far is too long.
(if (not (and fill-prefix
(looking-at fill-prefix-regexp)))
(setq fill-prefix
(buffer-substring (point)
(save-excursion (skip-chars-forward " \t") (point)))
fill-prefix-regexp
(regexp-quote fill-prefix)))
(forward-line 1)
;; Now stop the loop if end of paragraph.
(and (not (eobp))
(if fill-individual-varying-indent
;; If this line is a separator line, with or
;; without prefix, end the paragraph.
(and
(not (looking-at paragraph-separate))
(save-excursion
(not (and (looking-at fill-prefix-regexp)
(progn (forward-char (length fill-prefix))
(looking-at paragraph-separate))))))
;; If this line has more or less indent
;; than the fill prefix wants, end the paragraph.
(and (looking-at fill-prefix-regexp)
(save-excursion
(not (progn (forward-char (length fill-prefix))
(or (looking-at paragraph-separate)
(looking-at paragraph-start))))))))))
;; Fill this paragraph, but don't add a newline at the end.
(let ((had-newline (bolp)))
(fill-region-as-paragraph start (point) justifyp)
(or had-newline (delete-char -1))))))))
;;; fill.el ends here