Flávio Soibelmann Glock >
DateTime-Set >
Set::Infinite::_recurrence

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

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

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

- INFINITY
The

`Infinity`

value. - NEG_INFINITY
The

`-Infinity`

value.

Support is offered through the `datetime@perl.org`

mailing list.

Please report bugs using rt.cpan.org

Flavio Soibelmann Glock <fglock@gmail.com>

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

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.

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

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