lisp/gnus/flow-fill.el

   1 ;;; flow-fill.el --- interprete RFC2646 "flowed" text
   2
   3 ;; Copyright (C) 2000, 2002 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: encoding, 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
  50 ;;; Code:
  51
  52 (eval-when-compile (require 'cl))
  53
  54 (eval-and-compile
  55   (defalias 'fill-flowed-point-at-bol
  56         (if (fboundp 'point-at-bol)
  57             'point-at-bol
  58           'line-beginning-position))
  59
  60    (defalias 'fill-flowed-point-at-eol
  61         (if (fboundp 'point-at-eol)
  62             'point-at-eol
  63           'line-end-position)))
  64
  65 (defun fill-flowed (&optional buffer)
  66   (save-excursion
  67     (set-buffer (or (current-buffer) buffer))
  68     (goto-char (point-min))
  69     (while (re-search-forward " $" nil t)
  70       (when (save-excursion
  71               (beginning-of-line)
  72               (looking-at "^\\(>*\\)\\( ?\\)"))
  73         (let ((quote (match-string 1)) sig)
  74           (if (string= quote "")
  75               (setq quote nil))
  76           (when (and quote (string= (match-string 2) ""))
  77             (save-excursion
  78               ;; insert SP after quote for pleasant reading of quoted lines
  79               (beginning-of-line)
  80               (when (> (skip-chars-forward ">") 0)
  81                 (insert " "))))
  82           (while (and (save-excursion
  83                         (ignore-errors (backward-char 3))
  84                         (setq sig (looking-at "-- "))
  85                         (looking-at "[^-][^-] "))
  86                       (save-excursion
  87                         (unless (eobp)
  88                           (forward-char 1)
  89                           (looking-at (format "^\\(%s\\)\\([^>]\\)" (or quote " ?"))))))
  90             (save-excursion
  91               (replace-match (if (string= (match-string 2) " ")
  92                                  "" "\\2")))
  93             (backward-delete-char -1)
  94             (end-of-line))
  95           (unless sig
  96             (let ((fill-prefix (when quote (concat quote " "))))
  97               (fill-region (fill-flowed-point-at-bol)
  98                            (fill-flowed-point-at-eol)
  99                            'left 'nosqueeze))))))))
 100
 101 (provide 'flow-fill)
 102
 103 ;;; flow-fill.el ends here