POE::Filter::Line - serialize and parse terminated records (lines)

       Please see POE for more information about authors and contributors.

perl v5.34.0                                       2022-03-25                             POE::Filter::Line(3pm)

       The default input newline parser is a regexp that has an unfortunate race condition.  First the regular
       expression:

         /(\x0D\x0A?|\x0A\x0D?)/

       While it quickly recognizes most forms of newline, it can sometimes detect an extra blank line.  This
       happens when a two-byte newline character is broken between two reads.  Consider this situation:

         some stream dataCR
         LFother stream data

       The regular expression will see the first CR without its corresponding LF.  The filter will properly
       return "some stream data" as a line.  When the next packet arrives, the leading "LF" will be treated as
       the terminator for a 0-byte line.  The filter will faithfully return this empty line.

       Itisadvisedtospecifyliteralnewlinesorusetheautodetectfeatureinapplicationswhereblanklinesaresignificant.

       POE::Filter::Line parses stream data into terminated records.  The default parser interprets newlines as
       the record terminator, and the default serializer appends network newlines (CR/LF, or "\x0D\x0A") to
       outbound records.

       Record terminators are removed from the data POE::Filter::Line returns.

       POE::Filter::Line supports a number of other ways to parse lines.  Constructor parameters may specify
       literal newlines, regular expressions, or that the filter should detect newlines on its own.

       POE::Filter::Line - serialize and parse terminated records (lines)

       POE::Filter::Line has no additional public methods.

       Please see POE::Filter for documentation regarding the base interface.

       The SEE ALSO section in POE contains a table of contents covering the entire POE distribution.

       POE::Filter::Line exports the FIRST_UNUSED constant.  This points to the first unused element in the
       $self array reference.  Subclasses should store their own data beginning here, and they should export
       their own FIRST_UNUSED constants to help future subclassers.

         #!perl

         use POE qw(Wheel::FollowTail Filter::Line);

         POE::Session->create(
           inline_states => {
             _start => sub {
               $_[HEAP]{tailor} = POE::Wheel::FollowTail->new(
                 Filename => "/var/log/system.log",
                 InputEvent => "got_log_line",
                 Filter => POE::Filter::Line->new(),
               );
             },
             got_log_line => sub {
               print "Log: $_[ARG0]\n";
             }
           }
         );

         POE::Kernel->run();
         exit;