iso-2022 filter

[Takashi P.KATOH]

Hello,

  I think MHonArc does not handle iso-2022-jp headers (not
body) whether MIME encoded or not. Right?

So, I wrote the filter for iso-2022 like iso8859.pl.
I hope this benefits you.


By the way, I have one problem concerning this code:
Copyright Notice.

My name is written in preamble of this code, but almost all
part of this code is taken from m2h_text_plain'jp2022 (in
mhtxtplain.pl) by NIIBE Yutaka <[EMAIL PROTECTED]>.

Since I don't mind my name is written in this code or not
(that is, I don't mind disclaiming all copyright interest in
this code), please rewrite it if you need.

(Should it be ``Author: NIIBE Yutaka, [EMAIL PROTECTED]'' and
 ``Copyright (C) 19?? NIIBE Yutaka, [EMAIL PROTECTED]'' ?)


Best regards,

-- 
Takashi P.KATOH


##---------------------------------------------------------------------------##
##  File:
##      iso2022.pl 99/03/24
##  Author:
##      Takashi P.KATOH         <[EMAIL PROTECTED]>
##  Description:
##      Routines to process data encoded in iso2022 character sets.
##---------------------------------------------------------------------------##
##    Copyright (C) 1998,1999 Takashi P.KATOH, [EMAIL PROTECTED]
##
##    This program is free software; you can redistribute it and/or modify
##    it under the terms of the GNU General Public License as published by
##    the Free Software Foundation; either version 2 of the License, or
##    (at your option) any later version.
##
##    This program is distributed in the hope that it will be useful,
##    but WITHOUT ANY WARRANTY; without even the implied warranty of
##    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
##    GNU General Public License for more details.
##
##    You should have received a copy of the GNU General Public License
##    along with this program; if not, write to the Free Software
##    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
##    02111-1307, USA
##---------------------------------------------------------------------------##

package iso_2022;

###############################################################################
##      Routines
###############################################################################

##---------------------------------------------------------------------------##
##      str2sgml converts a string encoded by $charset to an sgml
##      string where special characters are converted to entity
##      references.
##
##      $return_data = iso_2022'str2sgml($data, $charset, $only8bit);
##
##      Notice:
##        $only8bit is not used.
##        (It is only for compatibility with iso_8859'str2sgml).
##
##        Almost all part of this code is taken from m2h_text_plain'jp2022
##        (in mhtxtplain.pl) by NIIBE Yutaka <[EMAIL PROTECTED]>.
##
sub str2sgml {
    local($data, $charset, $only8bit) = ($_[0], $_[1], $_[2]);
    local($ret, $ascii_text) = ('', '');

    local($_) = $data;

    # Process preceding ASCII text
    while(1) {
        if (s/^([^\033]+)//) {  # ASCII plain text
            $ascii_text = $1;

            # Replace meta characters in ASCII plain text
            $ascii_text =~ s%\&%\&amp;%g;
            $ascii_text =~ s%<%\&lt;%g;
            $ascii_text =~ s%>%\&gt;%g;
            ## Convert URLs to hyperlinks
            $ascii_text =~ s%($HUrlExp)%<A HREF="$1">$1</A>%gio
              unless $mhonarc::NOURL;

            $ret .= $ascii_text;
        } elsif (s/(\033\.[A-F])//) { # G2 Designate Sequence
            $ret .= $1;
        } elsif (s/(\033N[ -])//) { # Single Shift Sequence
            $ret .= $1;
        } else {
            last;
        }
    }

    # Process Each Segment
    while(1) {
        if (s/^(\033\([BJ])//) { # Single Byte Segment
            $ret .= $1;
            while(1) {
                if (s/^([^\033]+)//) {  # ASCII plain text
                    $ascii_text = $1;

                    # Replace meta characters in ASCII plain text
                    $ascii_text =~ s%\&%\&amp;%g;
                    $ascii_text =~ s%<%\&lt;%g;
                    $ascii_text =~ s%>%\&gt;%g;
                    ## Convert URLs to hyperlinks
                    $ascii_text =~ s%($HUrlExp)%<A HREF="$1">$1</A>%gio
                      unless $mhonarc::NOURL;

                    $ret .= $ascii_text;
                } elsif (s/(\033\.[A-F])//) { # G2 Designate Sequence
                    $ret .= $1;
                } elsif (s/(\033N[ -])//) { # Single Shift Sequence
                    $ret .= $1;
                } else {
                    last;
                }
            }
        } elsif (s/^(\033\$[\@AB]|\033\$\([CD])//) { # Double Byte Segment
            $ret .= $1;
            while (1) {
                if (s/^([!-~][!-~]+)//) { # Double Char plain text
                    $ret .= $1;
                } elsif (s/(\033\.[A-F])//) { # G2 Designate Sequence
                    $ret .= $1;
                } elsif (s/(\033N[ -])//) { # Single Shift Sequence
                    $ret .= $1;
                } else {
                    last;
                }
            }
        } else {
            # Something wrong in text
            $ret .= $_;
            last;
        }
    }
    $ret;
}

##---------------------------------------------------------------------------##
1;