Set::Infinite::_recurrence - Extends Set::Infinite with recurrence functions

       Flavio Soibelmann Glock <fglock@gmail.com>

       The recurrence generation algorithm is based on an idea from Dave Rolsky.

       •   INFINITY

           The "Infinity" value.

       •   NEG_INFINITY

           The "-Infinity" value.

       Copyright  (c) 2003 Flavio Soibelmann Glock. All rights reserved.  This program is free software; you can
       distribute it and/or modify it under the same terms as Perl itself.

       The full text of the license can be found in the LICENSE file included with this module.

       This is an internal class used by the DateTime::Set module.  The API is subject to change.

       It provides all functionality provided by Set::Infinite, plus the ability to define recurrences with
       arbitrary objects, such as dates.

       •   _recurrence ( \&next, \&previous )

           Creates a recurrence set. The set is defined inside a 'base set'.

              $recurrence = $base_set->_recurrence ( \&next, \&previous );

           The recurrence functions take one argument, and return the 'next' or the 'previous' occurrence.

           Example: defines the set of all 'integer numbers':

               use strict;

               use Set::Infinite::_recurrence;
               use POSIX qw(floor);

               # define the recurrence span
               my $forever = Set::Infinite::_recurrence->new(
                   Set::Infinite::_recurrence::NEG_INFINITY,
                   Set::Infinite::_recurrence::INFINITY
               );

               my $recurrence = $forever->_recurrence(
                   sub {   # next
                           floor( $_[0] + 1 )
                       },
                   sub {   # previous
                           my $tmp = floor( $_[0] );
                           $tmp < $_[0] ? $tmp : $_[0] - 1
                       },
               );

               print "sample recurrence ",
                     $recurrence->intersection( -5, 5 ), "\n";
               # sample recurrence -5,-4,-3,-2,-1,0,1,2,3,4,5

               {
                   my $x = 234.567;
                   print "next occurrence after $x = ",
                         $recurrence->{param}[0]->( $x ), "\n";  # 235
                   print "previous occurrence before $x = ",
                         $recurrence->{param}[2]->( $x ), "\n";  # 234
               }

               {
                   my $x = 234;
                   print "next occurrence after $x = ",
                         $recurrence->{param}[0]->( $x ), "\n";  # 235
                   print "previous occurrence before $x = ",
                         $recurrence->{param}[2]->( $x ), "\n";  # 233
               }

       •   is_forever

           Returns true if the set is a single span, ranging from -Infinity to Infinity.

       •   _is_recurrence

           Returns true if the set is an unbounded recurrence, ranging from -Infinity to Infinity.

       Set::Infinite::_recurrence - Extends Set::Infinite with recurrence functions

       Set::Infinite

       DateTime::Set

       For details on the Perl DateTime Suite project please see <http://datetime.perl.org>.

perl v5.34.0                                       2022-06-13                    Set::Infinite::_recurrence(3pm)

       Support is offered through the "datetime@perl.org" mailing list.

       Please report bugs using rt.cpan.org

           $recurrence = $base_set->_recurrence ( \&next, \&previous );