NAME

       Mail::DKIM::TextWrap - text wrapping module written for use with DKIM

VERSION

       version 1.20220520

DESCRIPTION

       This is a general-purpose text-wrapping module that I wrote because I had some specific
       needs with Mail::DKIM that none of the contemporary text-wrapping modules offered.

       Specifically, it offers the ability to change wrapping options in the middle of a
       paragraph. For instance, with a DKIM signature:

         DKIM-Signature: a=rsa; c=simple; h=first:second:third:fourth;
                 b=Xr2mo2wmb1LZBwmEJElIPezal7wQQkRQ8WZtxpofkNmXTjXf8y2f0

       the line-breaks can be inserted next to any of the colons of the h= tag, or any character
       of the b= tag. The way I implemented this was to serialize the signature one element at a
       time, changing the text-wrapping options at the start and end of each tag.

SYNOPSIS (FOR MAIL::DKIM USERS)

         use Mail::DKIM::TextWrap;

       Just add the above line to any program that uses Mail::DKIM::Signer and your signatures
       will automatically be wrapped to 72 characters.

SYNOPSIS (FOR OTHER USERS)

         my $output = "";
         my $tw = Mail::DKIM::TextWrap->new(
                         Margin => 10,
                         Output => \$output,
                     );
         $tw->add("Mary had a little lamb, whose fleece was white as snow.\n");
         $tw->finish;

         print $output;

TEXT WRAPPING OPTIONS

       Text wrapping options can be specified when calling new(), or by simply changing the
       property as needed. For example, to change the number of characters allowed per line:

         $tw->{Margin} = 20;

       Break
           a regular expression matching characters where a line break can be inserted. Line
           breaks are inserted AFTER a matching substring.  The default is "/\s/".

       BreakBefore
           a regular expression matching characters where a line break can be inserted. Line
           breaks are inserted BEFORE a matching substring.  Usually, you want to use Break,
           rather than BreakBefore.  The default is "undef".

       Margin
           specifies how many characters to allow per line.  The default is 72. If no place to
           line-break is found on a line, the line will extend beyond this margin.

       Separator
           the text to insert when a linebreak is needed.  The default is "\n". If you want to
           set a following-line indent (e.g. all lines but the first begin with four spaces), use
           something like "\n    ".

       Swallow
           a regular expression matching characters that can be omitted when a line break occurs.
           For example, if you insert a line break between two words, then you are replacing a
           "space" with the line break, so you are omitting the space. On the other hand, if you
           insert a line break between two parts of a hyphenated word, then you are breaking at
           the hyphen, but you still want to display the hyphen.  The default is "/\s/".

CONSTRUCTOR

   new() - create a new text-wrapping object
         my $tw = Mail::DKIM::TextWrap->new(
                             Output => \$output,
                             %wrapping_options,
                         );

       The text-wrapping object encapsulates the current options and the current state of the
       text stream. In addition to specifying text wrapping options as described in the section
       above, the following options are recognized:

       Output
           a scalar reference, or a glob reference, to specify where the "wrapped" text gets
           output to. If not specified, the default of STDOUT is used.

METHODS

   add() - process some text that can be wrapped
         $tw->add("Mary had a little lamb.\n");

       You can add() all the text at once, or add() the text in parts by calling add() multiple
       times.

   finish() - call when no more text is to be added
         $tw->finish;

       Call this when finished adding text, so that any remaining text in TextWrap's buffers will
       be output.

   flush() - output the current partial word, if any
         $tw->flush;

       Call this whenever changing TextWrap's parameters in the middle of a string of words. It
       explicitly allows a line-break at the current position in the string, regardless of
       whether it matches the current break pattern.

AUTHORS

       •   Jason Long <jason@long.name>

       •   Marc Bradshaw <marc@marcbradshaw.net>

       •   Bron Gondwana <brong@fastmailteam.com> (ARC)

THANKS

       Work on ensuring that this module passes the ARC test suite was generously sponsored by
       Valimail (https://www.valimail.com/)

COPYRIGHT AND LICENSE

       •   Copyright (C) 2013 by Messiah College

       •   Copyright (C) 2010 by Jason Long

       •   Copyright (C) 2017 by Standcore LLC

       •   Copyright (C) 2020 by FastMail Pty Ltd

       This library is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself, either Perl version 5.8.6 or, at your option, any later version of
       Perl 5 you may have available.