1 ;;; flow-fill.el --- interpret RFC2646 "flowed" text
3 ;; Copyright (C) 2000, 2001, 2002, 2003, 2004,
4 ;; 2005, 2006, 2007, 2008, 2009, 2010 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 3 of the License, or
14 ;; (at your option) any later version.
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. If not, see <http://www.gnu.org/licenses/>.
26 ;; This implement decoding of RFC2646 formatted text, including the
27 ;; quoted-depth wins rules.
29 ;; Theory of operation: search for lines ending with SPC, save quote
30 ;; length of line, remove SPC and concatenate line with the following
31 ;; line if quote length of following line matches current line.
33 ;; When no further concatenations are possible, we've found a
34 ;; paragraph and we let `fill-region' fill the long line into several
35 ;; lines with the quote prefix as `fill-prefix'.
37 ;; Todo: implement basic `fill-region' (Emacs and XEmacs
38 ;; implementations differ..)
42 ;; 2000-02-17 posted on ding mailing list
43 ;; 2000-02-19 use `point-at-{b,e}ol' in XEmacs
44 ;; 2000-03-11 no compile warnings for point-at-bol stuff
45 ;; 2000-03-26 committed to gnus cvs
46 ;; 2000-10-23 don't flow "-- " lines, make "quote-depth wins" rule
47 ;; work when first line is at level 0.
48 ;; 2002-01-12 probably incomplete encoding support
49 ;; 2003-12-08 started working on test harness.
53 (eval-when-compile (require 'cl))
55 (defcustom fill-flowed-display-column 'fill-column
56 "Column beyond which format=flowed lines are wrapped, when displayed.
57 This can be a Lisp expression or an integer."
60 :type '(choice (const :tag "Standard `fill-column'" fill-column)
61 (const :tag "Fit Window" (- (window-width) 5))
65 (defcustom fill-flowed-encode-column 66
66 "Column beyond which format=flowed lines are wrapped, in outgoing messages.
67 This can be a Lisp expression or an integer.
68 RFC 2646 suggests 66 characters for readability."
71 :type '(choice (const :tag "Standard fill-column" fill-column)
72 (const :tag "RFC 2646 default (66)" 66)
77 (defun fill-flowed-encode (&optional buffer)
78 (with-current-buffer (or buffer (current-buffer))
79 ;; No point in doing this unless hard newlines is used.
80 (when use-hard-newlines
81 (let ((start (point-min)) end)
82 ;; Go through each paragraph, filling it and adding SPC
83 ;; as the last character on each line.
84 (while (setq end (text-property-any start (point-max) 'hard 't))
85 (let ((fill-column (eval fill-flowed-encode-column)))
86 (fill-region start end t 'nosqueeze 'to-eop))
88 ;; `fill-region' probably distorted end.
89 (setq end (text-property-any start (point-max) 'hard 't))
90 (while (and (< (point) end)
91 (re-search-forward "$" (1- end) t))
95 (goto-char (setq start (1+ end)))))
99 (defun fill-flowed (&optional buffer delete-space)
101 (set-buffer (or (current-buffer) buffer))
102 (goto-char (point-min))
103 ;; Remove space stuffing.
104 (while (re-search-forward "^\\( \\|>+ $\\)" nil t)
107 (goto-char (point-min))
108 (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))
145 (fill-region (point-at-bol)
146 (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 ;; arch-tag: addc0040-bc53-4f17-b4bc-1eb44eed6f0b
225 ;;; flow-fill.el ends here