NAME
    MIME::Expander - Expands archived, compressed or multi-parted file by
    MIME mechanism

SYNOPSIS
        use MIME::Expander;
        use IO::All;

        my $callback = sub {
                my $em = shift; # is an Email::MIME object
                $em->body_raw > io( $em->filename );
            };
    
        my $exp = MIME::Expander->new;    
        my $num_contents = $exp->walk( io($ARGV[0])->all, $callback );
    
        print "total $num_contents are expanded.\n";

DESCRIPTION
    MIME::Expander is an utility module that expands archived, compressed or
    multi-parted file by MIME mechanism.

CONSTRUCTOR AND ACCESSORS
    The constructor new() creates an instance, and accepts a reference of
    hash as configurations.

    Following key of hash are available, and there is an access method of a
    same name.

    expects
        A value is a list reference and the elements are string or regular
        expression.

        If this parameter is set, then the walk() will not expand contents
        of specified mime types.

    guesser
        A value is a reference of code or reference of array which contains
        name of the "guess classes". In the case of a code, it is only
        performed for determining the mime type. In array, it performs in
        order of the element, and what was determined first is adopted.

        Each routines have to determine the type of the data which will be
        inputted.

        The parameters passed to a routine are a reference of scalar to
        contents, and information as reference of hash.

        Although the information may have a "filename", however depending on
        implements of each expander module, it may not be expectable.

        The routine have to return mime type string, or undef. If value of
        return is false value, that means "application/octet-stream".

        For example, sets routine which determine text or jpeg.

            my $exp = MIME::Expander->new({
                guesser => sub {
                        my $ref_contents = shift;
                        my $info         = shift || {};
                        if( defined $info->{filename} ){
                            my ($suffix) = $info->{filename} =~ /\.(.+)$/;
                            if( defined $suffix ){
                                if( lc $suffix eq 'txt' ){
                                    return 'text/plain';
                                }elsif( $suffix =~ /^jpe?g$/i ){
                                    return 'image/jpeg';
                                }
                            }
                        }
                    },
                });

        When useing the "guess classes", like this is the default of
        guesser, package name is omissible:

            my $exp = MIME::Expander->new({
                guesser => [qw/MMagic FileName/],
                });

        Please look in under namespace of MIME::Expander::Guess about what
        kinds of routine are available.

    depth
        A value is a native number.

        Please see "walk".

CLASS METHODS
  regulate_type( $type )
    Simplify when the type which removed "x-" is registered.

        MIME::Expander->regulate_type("text/plain; charset=ISO-2022-JP");
        #=> "text/plain"

        MIME::Expander->regulate_type('application/x-tar');
        #=> "application/tar"

    Please see about "simplified" in the document of MIME::Type.

INSTANCE METHODS
  init
    Initialize instance. This is for overriding.

  expects( \@list )
    Accessor to field "expects".

  is_expected( $type )
    Is $type the contents set to field "expects" ?

  depth( $native_number )
    Accessor to field "depth".

  guesser( \&code | \@list )
    Accessor to field "guesser".

  guess_type_of( \$contents, [\%info] )
    Determine mime type from the $contents.

    Optional %info is as hint for determing mime type. It will be passed to
    "guesser" directly.

    A key "filename" can be included in %info.

  plugin_for( $type )
    Please see the PLUGIN section.

  walk( \$data, $callback )
    If the $data which can be expanded in the inputted data exists, it will
    be expanded and passed to callback.

    The expanded data are further checked and processed recursively.

    The recursive depth is to the level of the value of "depth" field.

    A media object which is a Email::MIME, is passed to the callback
    routine, They are the results of this module.

    As the work, it sometimes often saves. However the file name may not be
    obtained with the specification of expander module. But it may be used,
    since it is set to "filename" attribute when it exists.

        $me->walk( \$data, sub {
                my $email = shift;
                my $name  = $email->filename;
                open my $fh, ">$name" or die;
                $fh->print($email->body_raw);
                close $fh;
            });

    See also Email::MIME about $email object.

    Only this $email object has rules on this MIME::Expander utility class.
    The expanded data is set to "body" and the Content-Transfer-Encoding is
    "binary". Therefore, in order to take out the expanded contents, please
    use "body_raw" method.

PLUGIN
    Expanding module for expand contents can be added as plug-in.

    Please see MIME::Expander::Plugin for details.

CAVEATS
    This version only implements in-memory decompression.

AUTHOR
    WATANABE Hiroaki <hwat@cpan.org>

LICENSE
    This library is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.

SEE ALSO
    Email::MIME

