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

   1 ;;; flow-fill.el --- interprete RFC2646 "flowed" text
   2
   3 ;; Copyright (C) 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
   4
   5 ;; Author: Simon Josefsson <jas@pdc.kth.se>
   6 ;; Keywords: mail
   7
   8 ;; This file is part of GNU Emacs.
   9
  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)
  13 ;; any later version.
  14
  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.
  19
  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.
  24
  25 ;;; Commentary:
  26
  27 ;; This implement decoding of RFC2646 formatted text, including the
  28 ;; quoted-depth wins rules.
  29
  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.
  33
  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'.
  37
  38 ;; Todo: implement basic `fill-region' (Emacs and XEmacs
  39 ;;       implementations differ..)
  40
  41 ;;; History:
  42
  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.
  51
  52 ;;; Code:
  53
  54 (eval-when-compile (require 'cl))
  55
  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   :group 'mime-display
  60   :type '(choice (const :tag "Standard `fill-column'" fill-column)
  61                  (const :tag "Fit Window" (- (window-width) 5))
  62                  (sexp)
  63                  (integer)))
  64
  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."
  69   :group 'mime-display
  70   :type '(choice (const :tag "Standard fill-column" fill-column)
  71                  (const :tag "RFC 2646 default (66)" 66)
  72                  (sexp)
  73                  (integer)))
  74
  75 (eval-and-compile
  76   (defalias 'fill-flowed-point-at-bol
  77         (if (fboundp 'point-at-bol)
  78             'point-at-bol
  79           'line-beginning-position))
  80
  81    (defalias 'fill-flowed-point-at-eol
  82         (if (fboundp 'point-at-eol)
  83             'point-at-eol
  84           'line-end-position)))
  85
  86 ;;;###autoload
  87 (defun fill-flowed-encode (&optional buffer)
  88   (with-current-buffer (or buffer (current-buffer))
  89     ;; No point in doing this unless hard newlines is used.
  90     (when use-hard-newlines
  91       (let ((start (point-min)) end)
  92         ;; Go through each paragraph, filling it and adding SPC
  93         ;; as the last character on each line.
  94         (while (setq end (text-property-any start (point-max) 'hard 't))
  95           (let ((fill-column (eval fill-flowed-encode-column)))
  96             (fill-region start end t 'nosqueeze 'to-eop))
  97           (goto-char start)
  98           ;; `fill-region' probably distorted end.
  99           (setq end (text-property-any start (point-max) 'hard 't))
 100           (while (and (< (point) end)
 101                       (re-search-forward "$" (1- end) t))
 102             (insert " ")
 103             (setq end (1+ end))
 104             (forward-char))
 105           (goto-char (setq start (1+ end)))))
 106       t)))
 107
 108 ;;;###autoload
 109 (defun fill-flowed (&optional buffer)
 110   (save-excursion
 111     (set-buffer (or (current-buffer) buffer))
 112     (goto-char (point-min))
 113     (while (re-search-forward " $" nil t)
 114       (when (save-excursion
 115               (beginning-of-line)
 116               (looking-at "^\\(>*\\)\\( ?\\)"))
 117         (let ((quote (match-string 1))
 118               sig)
 119           (if (string= quote "")
 120               (setq quote nil))
 121           (when (and quote (string= (match-string 2) ""))
 122             (save-excursion
 123               ;; insert SP after quote for pleasant reading of quoted lines
 124               (beginning-of-line)
 125               (when (> (skip-chars-forward ">") 0)
 126                 (insert " "))))
 127           ;; XXX slightly buggy handling of "-- "
 128           (while (and (save-excursion
 129                         (ignore-errors (backward-char 3))
 130                         (setq sig (looking-at "-- "))
 131                         (looking-at "[^-][^-] "))
 132                       (save-excursion
 133                         (unless (eobp)
 134                           (forward-char 1)
 135                           (looking-at (format "^\\(%s\\)\\([^>\n\r]\\)"
 136                                               (or quote " ?"))))))
 137             (save-excursion
 138               (replace-match (if (string= (match-string 2) " ")
 139                                  "" "\\2")))
 140             (backward-delete-char -1)
 141             (end-of-line))
 142           (unless sig
 143             (condition-case nil
 144                 (let ((fill-prefix (when quote (concat quote " ")))
 145                       (fill-column (eval fill-flowed-display-column))
 146                       filladapt-mode)
 147                   (fill-region (fill-flowed-point-at-bol)
 148                                (min (1+ (fill-flowed-point-at-eol))
 149                                     (point-max))
 150                                'left 'nosqueeze))
 151               (error
 152                (forward-line 1)
 153                nil))))))))
 154
 155 ;; Test vectors.
 156
 157 (eval-when-compile
 158   (defvar show-trailing-whitespace))
 159
 160 (defvar fill-flowed-encode-tests
 161   '(
 162     ;; The syntax of each list element is:
 163     ;; (INPUT . EXPECTED-OUTPUT)
 164     ("> Thou villainous ill-breeding spongy dizzy-eyed
 165 > reeky elf-skinned pigeon-egg!
 166 >> Thou artless swag-bellied milk-livered
 167 >> dismal-dreaming idle-headed scut!
 168 >>> Thou errant folly-fallen spleeny reeling-ripe
 169 >>> unmuzzled ratsbane!
 170 >>>> Henceforth, the coding style is to be strictly
 171 >>>> enforced, including the use of only upper case.
 172 >>>>> I've noticed a lack of adherence to the coding
 173 >>>>> styles, of late.
 174 >>>>>> Any complaints?
 175 " . "> Thou villainous ill-breeding spongy dizzy-eyed reeky elf-skinned
 176 > pigeon-egg!
 177 >> Thou artless swag-bellied milk-livered dismal-dreaming idle-headed
 178 >> scut!
 179 >>> Thou errant folly-fallen spleeny reeling-ripe unmuzzled ratsbane!
 180 >>>> Henceforth, the coding style is to be strictly enforced,
 181 >>>> including the use of only upper case.
 182 >>>>> I've noticed a lack of adherence to the coding styles, of late.
 183 >>>>>> Any complaints?
 184 ")
 185 ;    ("
 186 ;> foo
 187 ;>
 188 ;>
 189 ;> bar
 190 ;" . "
 191 ;> foo bar
 192 ;")
 193     ))
 194
 195 (defun fill-flowed-test ()
 196   (interactive "")
 197   (switch-to-buffer (get-buffer-create "*Format=Flowed test output*"))
 198   (erase-buffer)
 199   (setq show-trailing-whitespace t)
 200   (dolist (test fill-flowed-encode-tests)
 201     (let (start output)
 202       (insert "***** BEGIN TEST INPUT *****\n")
 203       (insert (car test))
 204       (insert "***** END TEST INPUT *****\n\n")
 205       (insert "***** BEGIN TEST OUTPUT *****\n")
 206       (setq start (point))
 207       (insert (car test))
 208       (save-restriction
 209         (narrow-to-region start (point))
 210         (fill-flowed))
 211       (setq output (buffer-substring start (point-max)))
 212       (insert "***** END TEST OUTPUT *****\n")
 213       (unless (string= output (cdr test))
 214         (insert "\n***** BEGIN TEST EXPECTED OUTPUT *****\n")
 215         (insert (cdr test))
 216         (insert "***** END TEST EXPECTED OUTPUT *****\n"))
 217       (insert "\n\n")))
 218   (goto-char (point-max)))
 219
 220 (provide 'flow-fill)
 221
 222 ;;; arch-tag: addc0040-bc53-4f17-b4bc-1eb44eed6f0b
 223 ;;; flow-fill.el ends here