1 ;;; flow-fill.el --- interpret RFC2646 "flowed" text
3 ;; Copyright (C) 2000, 2001, 2002, 2003, 2004,
4 ;; 2005 Free Software Foundation, Inc.
6 ;; Author: Simon Josefsson <jas@pdc.kth.se>
9 ;; This file is part of GNU Emacs.
11 ;; GNU Emacs is free software; you can redistribute it and/or modify
12 ;; it under the terms of the GNU General Public License as published by
13 ;; the Free Software Foundation; either version 2, or (at your option)
16 ;; GNU Emacs is distributed in the hope that it will be useful,
17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 ;; GNU General Public License for more details.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with GNU Emacs; see the file COPYING. If not, write to the
23 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
24 ;; Boston, MA 02110-1301, USA.
28 ;; This implement decoding of RFC2646 formatted text, including the
29 ;; quoted-depth wins rules.
31 ;; Theory of operation: search for lines ending with SPC, save quote
32 ;; length of line, remove SPC and concatenate line with the following
33 ;; line if quote length of following line matches current line.
35 ;; When no further concatenations are possible, we've found a
36 ;; paragraph and we let `fill-region' fill the long line into several
37 ;; lines with the quote prefix as `fill-prefix'.
39 ;; Todo: implement basic `fill-region' (Emacs and XEmacs
40 ;; implementations differ..)
44 ;; 2000-02-17 posted on ding mailing list
45 ;; 2000-02-19 use `point-at-{b,e}ol' in XEmacs
46 ;; 2000-03-11 no compile warnings for point-at-bol stuff
47 ;; 2000-03-26 committed to gnus cvs
48 ;; 2000-10-23 don't flow "-- " lines, make "quote-depth wins" rule
49 ;; work when first line is at level 0.
50 ;; 2002-01-12 probably incomplete encoding support
51 ;; 2003-12-08 started working on test harness.
55 (eval-when-compile (require 'cl))
57 (defcustom fill-flowed-display-column 'fill-column
58 "Column beyond which format=flowed lines are wrapped, when displayed.
59 This can be a Lisp expression or an integer."
62 :type '(choice (const :tag "Standard `fill-column'" fill-column)
63 (const :tag "Fit Window" (- (window-width) 5))
67 (defcustom fill-flowed-encode-column 66
68 "Column beyond which format=flowed lines are wrapped, in outgoing messages.
69 This can be a Lisp expression or an integer.
70 RFC 2646 suggests 66 characters for readability."
73 :type '(choice (const :tag "Standard fill-column" fill-column)
74 (const :tag "RFC 2646 default (66)" 66)
79 (defun fill-flowed-encode (&optional buffer)
80 (with-current-buffer (or buffer (current-buffer))
81 ;; No point in doing this unless hard newlines is used.
82 (when use-hard-newlines
83 (let ((start (point-min)) end)
84 ;; Go through each paragraph, filling it and adding SPC
85 ;; as the last character on each line.
86 (while (setq end (text-property-any start (point-max) 'hard 't))
87 (let ((fill-column (eval fill-flowed-encode-column)))
88 (fill-region start end t 'nosqueeze 'to-eop))
90 ;; `fill-region' probably distorted end.
91 (setq end (text-property-any start (point-max) 'hard 't))
92 (while (and (< (point) end)
93 (re-search-forward "$" (1- end) t))
97 (goto-char (setq start (1+ end)))))
101 (defun fill-flowed (&optional buffer)
103 (set-buffer (or (current-buffer) buffer))
104 (goto-char (point-min))
105 ;; Remove space stuffing.
106 (while (re-search-forward "^ " nil t)
109 (goto-char (point-min))
110 (while (re-search-forward " $" nil t)
111 (when (save-excursion
113 (looking-at "^\\(>*\\)\\( ?\\)"))
114 (let ((quote (match-string 1))
116 (if (string= quote "")
118 (when (and quote (string= (match-string 2) ""))
120 ;; insert SP after quote for pleasant reading of quoted lines
122 (when (> (skip-chars-forward ">") 0)
124 ;; XXX slightly buggy handling of "-- "
125 (while (and (save-excursion
126 (ignore-errors (backward-char 3))
127 (setq sig (looking-at "-- "))
128 (looking-at "[^-][^-] "))
132 (looking-at (format "^\\(%s\\)\\([^>\n\r]\\)"
135 (replace-match (if (string= (match-string 2) " ")
137 (backward-delete-char -1)
141 (let ((fill-prefix (when quote (concat quote " ")))
142 (fill-column (eval fill-flowed-display-column))
144 (fill-region (point-at-bol)
145 (min (1+ (point-at-eol))
155 (defvar show-trailing-whitespace))
157 (defvar fill-flowed-encode-tests
159 ;; The syntax of each list element is:
160 ;; (INPUT . EXPECTED-OUTPUT)
162 "> Thou villainous ill-breeding spongy dizzy-eyed \n"
163 "> reeky elf-skinned pigeon-egg! \n"
164 ">> Thou artless swag-bellied milk-livered \n"
165 ">> dismal-dreaming idle-headed scut!\n"
166 ">>> Thou errant folly-fallen spleeny reeling-ripe \n"
167 ">>> unmuzzled ratsbane!\n"
168 ">>>> Henceforth, the coding style is to be strictly \n"
169 ">>>> enforced, including the use of only upper case.\n"
170 ">>>>> I've noticed a lack of adherence to the coding \n"
171 ">>>>> styles, of late.\n"
172 ">>>>>> Any complaints?")
175 "> Thou villainous ill-breeding spongy dizzy-eyed reeky elf-skinned\n"
177 ">> Thou artless swag-bellied milk-livered dismal-dreaming idle-headed\n"
179 ">>> Thou errant folly-fallen spleeny reeling-ripe unmuzzled ratsbane!\n"
180 ">>>> Henceforth, the coding style is to be strictly enforced,\n"
181 ">>>> including the use of only upper case.\n"
182 ">>>>> I've noticed a lack of adherence to the coding styles, of late.\n"
183 ">>>>>> Any complaints?\n"
197 (defun fill-flowed-test ()
199 (switch-to-buffer (get-buffer-create "*Format=Flowed test output*"))
201 (setq show-trailing-whitespace t)
202 (dolist (test fill-flowed-encode-tests)
204 (insert "***** BEGIN TEST INPUT *****\n")
206 (insert "***** END TEST INPUT *****\n\n")
207 (insert "***** BEGIN TEST OUTPUT *****\n")
211 (narrow-to-region start (point))
213 (setq output (buffer-substring start (point-max)))
214 (insert "***** END TEST OUTPUT *****\n")
215 (unless (string= output (cdr test))
216 (insert "\n***** BEGIN TEST EXPECTED OUTPUT *****\n")
218 (insert "***** END TEST EXPECTED OUTPUT *****\n"))
220 (goto-char (point-max)))
224 ;;; flow-fill.el ends here