1 ;;; flow-fill.el --- interpret RFC2646 "flowed" text
3 ;; Copyright (C) 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
5 ;; Author: Simon Josefsson <jas@pdc.kth.se>
8 ;; This file is part of GNU Emacs.
10 ;; GNU Emacs is free software; you can redistribute it and/or modify
11 ;; it under the terms of the GNU General Public License as published by
12 ;; the Free Software Foundation; either version 2, or (at your option)
15 ;; GNU Emacs is distributed in the hope that it will be useful,
16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 ;; GNU General Public License for more details.
20 ;; You should have received a copy of the GNU General Public License
21 ;; along with GNU Emacs; see the file COPYING. If not, write to the
22 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
23 ;; Boston, MA 02111-1307, USA.
27 ;; This implement decoding of RFC2646 formatted text, including the
28 ;; quoted-depth wins rules.
30 ;; Theory of operation: search for lines ending with SPC, save quote
31 ;; length of line, remove SPC and concatenate line with the following
32 ;; line if quote length of following line matches current line.
34 ;; When no further concatenations are possible, we've found a
35 ;; paragraph and we let `fill-region' fill the long line into several
36 ;; lines with the quote prefix as `fill-prefix'.
38 ;; Todo: implement basic `fill-region' (Emacs and XEmacs
39 ;; implementations differ..)
43 ;; 2000-02-17 posted on ding mailing list
44 ;; 2000-02-19 use `point-at-{b,e}ol' in XEmacs
45 ;; 2000-03-11 no compile warnings for point-at-bol stuff
46 ;; 2000-03-26 committed to gnus cvs
47 ;; 2000-10-23 don't flow "-- " lines, make "quote-depth wins" rule
48 ;; work when first line is at level 0.
49 ;; 2002-01-12 probably incomplete encoding support
50 ;; 2003-12-08 started working on test harness.
54 (eval-when-compile (require 'cl))
56 (defcustom fill-flowed-display-column 'fill-column
57 "Column beyond which format=flowed lines are wrapped, when displayed.
58 This can be a Lisp expression or an integer."
59 :type '(choice (const :tag "Standard `fill-column'" fill-column)
60 (const :tag "Fit Window" (- (window-width) 5))
64 (defcustom fill-flowed-encode-column 66
65 "Column beyond which format=flowed lines are wrapped, in outgoing messages.
66 This can be a Lisp expression or an integer.
67 RFC 2646 suggests 66 characters for readability."
68 :type '(choice (const :tag "Standard fill-column" fill-column)
69 (const :tag "RFC 2646 default (66)" 66)
74 (defun fill-flowed-encode (&optional buffer)
75 (with-current-buffer (or buffer (current-buffer))
76 ;; No point in doing this unless hard newlines is used.
77 (when use-hard-newlines
78 (let ((start (point-min)) end)
79 ;; Go through each paragraph, filling it and adding SPC
80 ;; as the last character on each line.
81 (while (setq end (text-property-any start (point-max) 'hard 't))
82 (let ((fill-column (eval fill-flowed-encode-column)))
83 (fill-region start end t 'nosqueeze 'to-eop))
85 ;; `fill-region' probably distorted end.
86 (setq end (text-property-any start (point-max) 'hard 't))
87 (while (and (< (point) end)
88 (re-search-forward "$" (1- end) t))
92 (goto-char (setq start (1+ end)))))
96 (defun fill-flowed (&optional buffer)
98 (set-buffer (or (current-buffer) buffer))
99 (goto-char (point-min))
100 ;; Remove space stuffing.
101 (while (re-search-forward "^ " nil t)
104 (goto-char (point-min))
105 (while (re-search-forward " $" nil t)
106 (when (save-excursion
108 (looking-at "^\\(>+\\)\\( ?\\)"))
109 (let ((quote (match-string 1))
111 (if (string= quote "")
113 (when (and quote (string= (match-string 2) ""))
115 ;; insert SP after quote for pleasant reading of quoted lines
117 (when (> (skip-chars-forward ">") 0)
119 ;; XXX slightly buggy handling of "-- "
120 (while (and (save-excursion
121 (ignore-errors (backward-char 3))
122 (setq sig (looking-at "-- "))
123 (looking-at "[^-][^-] "))
127 (looking-at (format "^\\(%s\\)\\([^>\n\r]\\)"
130 (replace-match (if (string= (match-string 2) " ")
132 (backward-delete-char -1)
136 (let ((fill-prefix (when quote (concat quote " ")))
137 (fill-column (eval fill-flowed-display-column))
139 (fill-region (point-at-bol)
140 (min (1+ (point-at-eol))
150 (defvar show-trailing-whitespace))
152 (defvar fill-flowed-encode-tests
154 ;; The syntax of each list element is:
155 ;; (INPUT . EXPECTED-OUTPUT)
156 ("> Thou villainous ill-breeding spongy dizzy-eyed
157 > reeky elf-skinned pigeon-egg!
158 >> Thou artless swag-bellied milk-livered
159 >> dismal-dreaming idle-headed scut!
160 >>> Thou errant folly-fallen spleeny reeling-ripe
161 >>> unmuzzled ratsbane!
162 >>>> Henceforth, the coding style is to be strictly
163 >>>> enforced, including the use of only upper case.
164 >>>>> I've noticed a lack of adherence to the coding
165 >>>>> styles, of late.
166 >>>>>> Any complaints?
167 " . "> Thou villainous ill-breeding spongy dizzy-eyed reeky elf-skinned
169 >> Thou artless swag-bellied milk-livered dismal-dreaming idle-headed
171 >>> Thou errant folly-fallen spleeny reeling-ripe unmuzzled ratsbane!
172 >>>> Henceforth, the coding style is to be strictly enforced,
173 >>>> including the use of only upper case.
174 >>>>> I've noticed a lack of adherence to the coding styles, of late.
175 >>>>>> Any complaints?
187 (defun fill-flowed-test ()
189 (switch-to-buffer (get-buffer-create "*Format=Flowed test output*"))
191 (setq show-trailing-whitespace t)
192 (dolist (test fill-flowed-encode-tests)
194 (insert "***** BEGIN TEST INPUT *****\n")
196 (insert "***** END TEST INPUT *****\n\n")
197 (insert "***** BEGIN TEST OUTPUT *****\n")
201 (narrow-to-region start (point))
203 (setq output (buffer-substring start (point-max)))
204 (insert "***** END TEST OUTPUT *****\n")
205 (unless (string= output (cdr test))
206 (insert "\n***** BEGIN TEST EXPECTED OUTPUT *****\n")
208 (insert "***** END TEST EXPECTED OUTPUT *****\n"))
210 (goto-char (point-max)))
214 ;;; flow-fill.el ends here