code.delx.au - gnu-emacs/blob - lisp/gnus/flow-fill.el

   1 ;;; flow-fill.el --- interpret RFC2646 "flowed" text
   2
   3 ;; Copyright (C) 2000, 2001, 2002, 2003, 2004,
   4 ;;   2005 Free Software Foundation, Inc.
   5
   6 ;; Author: Simon Josefsson <jas@pdc.kth.se>
   7 ;; Keywords: mail
   8
   9 ;; This file is part of GNU Emacs.
  10
  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)
  14 ;; any later version.
  15
  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.
  20
  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.
  25
  26 ;;; Commentary:
  27
  28 ;; This implement decoding of RFC2646 formatted text, including the
  29 ;; quoted-depth wins rules.
  30
  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.
  34
  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'.
  38
  39 ;; Todo: implement basic `fill-region' (Emacs and XEmacs
  40 ;;       implementations differ..)
  41
  42 ;;; History:
  43
  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.
  52
  53 ;;; Code:
  54
  55 (eval-when-compile (require 'cl))
  56
  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."
  60   :version "22.1"
  61   :group 'mime-display
  62   :type '(choice (const :tag "Standard `fill-column'" fill-column)
  63                  (const :tag "Fit Window" (- (window-width) 5))
  64                  (sexp)
  65                  (integer)))
  66
  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."
  71   :version "22.1"
  72   :group 'mime-display
  73   :type '(choice (const :tag "Standard fill-column" fill-column)
  74                  (const :tag "RFC 2646 default (66)" 66)
  75                  (sexp)
  76                  (integer)))
  77
  78 (eval-and-compile
  79   (defalias 'fill-flowed-point-at-bol
  80         (if (fboundp 'point-at-bol)
  81             'point-at-bol
  82           'line-beginning-position))
  83
  84    (defalias 'fill-flowed-point-at-eol
  85         (if (fboundp 'point-at-eol)
  86             'point-at-eol
  87           'line-end-position)))
  88
  89 ;;;###autoload
  90 (defun fill-flowed-encode (&optional buffer)
  91   (with-current-buffer (or buffer (current-buffer))
  92     ;; No point in doing this unless hard newlines is used.
  93     (when use-hard-newlines
  94       (let ((start (point-min)) end)
  95         ;; Go through each paragraph, filling it and adding SPC
  96         ;; as the last character on each line.
  97         (while (setq end (text-property-any start (point-max) 'hard 't))
  98           (let ((fill-column (eval fill-flowed-encode-column)))
  99             (fill-region start end t 'nosqueeze 'to-eop))
 100           (goto-char start)
 101           ;; `fill-region' probably distorted end.
 102           (setq end (text-property-any start (point-max) 'hard 't))
 103           (while (and (< (point) end)
 104                       (re-search-forward "$" (1- end) t))
 105             (insert " ")
 106             (setq end (1+ end))
 107             (forward-char))
 108           (goto-char (setq start (1+ end)))))
 109       t)))
 110
 111 ;;;###autoload
 112 (defun fill-flowed (&optional buffer)
 113   (save-excursion
 114     (set-buffer (or (current-buffer) buffer))
 115     (goto-char (point-min))
 116     (while (re-search-forward " $" nil t)
 117       (when (save-excursion
 118               (beginning-of-line)
 119               (looking-at "^\\(>*\\)\\( ?\\)"))
 120         (let ((quote (match-string 1))
 121               sig)
 122           (if (string= quote "")
 123               (setq quote nil))
 124           (when (and quote (string= (match-string 2) ""))
 125             (save-excursion
 126               ;; insert SP after quote for pleasant reading of quoted lines
 127               (beginning-of-line)
 128               (when (> (skip-chars-forward ">") 0)
 129                 (insert " "))))
 130           ;; XXX slightly buggy handling of "-- "
 131           (while (and (save-excursion
 132                         (ignore-errors (backward-char 3))
 133                         (setq sig (looking-at "-- "))
 134                         (looking-at "[^-][^-] "))
 135                       (save-excursion
 136                         (unless (eobp)
 137                           (forward-char 1)
 138                           (looking-at (format "^\\(%s\\)\\([^>\n\r]\\)"
 139                                               (or quote " ?"))))))
 140             (save-excursion
 141               (replace-match (if (string= (match-string 2) " ")
 142                                  "" "\\2")))
 143             (backward-delete-char -1)
 144             (end-of-line))
 145           (unless sig
 146             (condition-case nil
 147                 (let ((fill-prefix (when quote (concat quote " ")))
 148                       (fill-column (eval fill-flowed-display-column))
 149                       filladapt-mode)
 150                   (fill-region (fill-flowed-point-at-bol)
 151                                (min (1+ (fill-flowed-point-at-eol))
 152                                     (point-max))
 153                                'left 'nosqueeze))
 154               (error
 155                (forward-line 1)
 156                nil))))))))
 157
 158 ;; Test vectors.
 159
 160 (eval-when-compile
 161   (defvar show-trailing-whitespace))
 162
 163 (defvar fill-flowed-encode-tests
 164   '(
 165     ;; The syntax of each list element is:
 166     ;; (INPUT . EXPECTED-OUTPUT)
 167     ("> Thou villainous ill-breeding spongy dizzy-eyed
 168 > reeky elf-skinned pigeon-egg!
 169 >> Thou artless swag-bellied milk-livered
 170 >> dismal-dreaming idle-headed scut!
 171 >>> Thou errant folly-fallen spleeny reeling-ripe
 172 >>> unmuzzled ratsbane!
 173 >>>> Henceforth, the coding style is to be strictly
 174 >>>> enforced, including the use of only upper case.
 175 >>>>> I've noticed a lack of adherence to the coding
 176 >>>>> styles, of late.
 177 >>>>>> Any complaints?
 178 " . "> Thou villainous ill-breeding spongy dizzy-eyed reeky elf-skinned
 179 > pigeon-egg!
 180 >> Thou artless swag-bellied milk-livered dismal-dreaming idle-headed
 181 >> scut!
 182 >>> Thou errant folly-fallen spleeny reeling-ripe unmuzzled ratsbane!
 183 >>>> Henceforth, the coding style is to be strictly enforced,
 184 >>>> including the use of only upper case.
 185 >>>>> I've noticed a lack of adherence to the coding styles, of late.
 186 >>>>>> Any complaints?
 187 ")
 188 ;    ("
 189 ;> foo
 190 ;>
 191 ;>
 192 ;> bar
 193 ;" . "
 194 ;> foo bar
 195 ;")
 196     ))
 197
 198 (defun fill-flowed-test ()
 199   (interactive "")
 200   (switch-to-buffer (get-buffer-create "*Format=Flowed test output*"))
 201   (erase-buffer)
 202   (setq show-trailing-whitespace t)
 203   (dolist (test fill-flowed-encode-tests)
 204     (let (start output)
 205       (insert "***** BEGIN TEST INPUT *****\n")
 206       (insert (car test))
 207       (insert "***** END TEST INPUT *****\n\n")
 208       (insert "***** BEGIN TEST OUTPUT *****\n")
 209       (setq start (point))
 210       (insert (car test))
 211       (save-restriction
 212         (narrow-to-region start (point))
 213         (fill-flowed))
 214       (setq output (buffer-substring start (point-max)))
 215       (insert "***** END TEST OUTPUT *****\n")
 216       (unless (string= output (cdr test))
 217         (insert "\n***** BEGIN TEST EXPECTED OUTPUT *****\n")
 218         (insert (cdr test))
 219         (insert "***** END TEST EXPECTED OUTPUT *****\n"))
 220       (insert "\n\n")))
 221   (goto-char (point-max)))
 222
 223 (provide 'flow-fill)
 224
 225 ;;; arch-tag: addc0040-bc53-4f17-b4bc-1eb44eed6f0b
 226 ;;; flow-fill.el ends here