NAME

SYNOPSIS

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

DESCRIPTION

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

METHODS

• _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.

CONSTANTS

• INFINITY

  The "Infinity" value.

• NEG_INFINITY

  The "-Infinity" value.

SUPPORT

Please report bugs using rt.cpan.org

AUTHOR

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

COPYRIGHT

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

SEE ALSO

DateTime::Set

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