#-*- perl -*-
#
#  Copyright (C) 2001 Ken'ichi Fukamachi
#   All rights reserved. This program is free software; you can
#   redistribute it and/or modify it under the same terms as Perl itself. 
#
# $Id$
# $FML$
#

package Dialect::Japanese::Utils;
use strict;
use vars qw(@ISA @EXPORT @EXPORT_OK $AUTOLOAD);
use Carp;

=head1 NAME

Dialect::Japanese::Utils - what is this

=head1 SYNOPSIS

   use Dialect::Japanese::Utils qw(is_iso2022jp_string);
   if ( is_iso2022jp_string($string) ) { do_something_if_Japanese;}

=head1 DESCRIPTION

Utilities for Japanse string

=head1 METHODS

=head2 <is_iso2022jp_string($string)>

check whether $string looks Japanese. 
return 1 if it looks so.

=cut

require Exporter;

@ISA       = qw(Exporter);
@EXPORT_OK = qw(is_iso2022jp_string);


sub is_iso2022jp_string
{
    my ($buf) = @_;
    return (not _look_not_iso2022jp_string($buf));
}


# based on fml-support: 07020, 07029
#   Koji Sudo <koji@cherry.or.jp>
#   Takahiro Kambe <taca@sky.yamashina.kyoto.jp>
# check the given buffer has unusual Japanese (not ISO-2022-JP)
sub _look_not_iso2022jp_string
{
    my ($buf) = @_;

    # check 8 bit on
    if ($buf =~ /[\x80-\xFF]/){
        return 1;
    }

    # check SI/SO
    if ($buf =~ /[\016\017]/) {
        return 1;
    }

    # HANKAKU KANA
    if ($buf =~ /\033\(I/) {
        return 1;
    }

    # MSB flag or other control sequences
    if ($buf =~ /[\001-\007\013\015\020-\032\034-\037\177-\377]/) {
        return 1;
    }

    0; # O.K.
}



=head1 AUTHOR

Ken'ichi Fukamachi

=head1 COPYRIGHT

Copyright (C) 2001 Ken'ichi Fukamachi

All rights reserved. This program is free software; you can
redistribute it and/or modify it under the same terms as Perl itself. 

=head1 HISTORY

Dialect::Japanese::Utils appeared in fml5 mailing list driver package.
See C<http://www.fml.org/> for more details.

=cut

1;