Set::Infinite::_recurrence(3pm)

1Set::Infinite::_recurreUnsceer(3C)ontributed Perl DocumeSnetta:t:iIonnfinite::_recurrence(3)
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NAME

6       Set::Infinite::_recurrence - Extends Set::Infinite with recurrence
7       functions
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SYNOPSIS

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

13       This is an internal class used by the DateTime::Set module.  The API is
14       subject to change.
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16       It provides all functionality provided by Set::Infinite, plus the abil‐
17       ity to define recurrences with arbitrary objects, such as dates.
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METHODS

20       * _recurrence ( \&next, \&previous )
21           Creates a recurrence set. The set is defined inside a 'base set'.
22
23              $recurrence = $base_set->_recurrence ( \&next, \&previous );
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25           The recurrence functions take one argument, and return the 'next'
26           or the 'previous' occurence.
27
28           Example: defines the set of all 'integer numbers':
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30               use strict;
31
32               use Set::Infinite::_recurrence;
33               use POSIX qw(floor);
34
35               # define the recurrence span
36               my $forever = Set::Infinite::_recurrence->new(
37                   Set::Infinite::_recurrence::NEG_INFINITY,
38                   Set::Infinite::_recurrence::INFINITY
39               );
40
41               my $recurrence = $forever->_recurrence(
42                   sub {   # next
43                           floor( $_[0] + 1 )
44                       },
45                   sub {   # previous
46                           my $tmp = floor( $_[0] );
47                           $tmp < $_[0] ? $tmp : $_[0] - 1
48                       },
49               );
50
51               print "sample recurrence ",
52                     $recurrence->intersection( -5, 5 ), "\n";
53               # sample recurrence -5,-4,-3,-2,-1,0,1,2,3,4,5
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55               {
56                   my $x = 234.567;
57                   print "next occurence after $x = ",
58                         $recurrence->{param}[0]->( $x ), "\n";  # 235
59                   print "previous occurence before $x = ",
60                         $recurrence->{param}[2]->( $x ), "\n";  # 234
61               }
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63               {
64                   my $x = 234;
65                   print "next occurence after $x = ",
66                         $recurrence->{param}[0]->( $x ), "\n";  # 235
67                   print "previous occurence before $x = ",
68                         $recurrence->{param}[2]->( $x ), "\n";  # 233
69               }
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71       * is_forever
72           Returns true if the set is a single span, ranging from -Infinity to
73           Infinity.
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75       * _is_recurrence
76           Returns true if the set is an unbounded recurrence, ranging from
77           -Infinity to Infinity.
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CONSTANTS

80       * INFINITY
81           The "Infinity" value.
82
83       * NEG_INFINITY
84           The "-Infinity" value.
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SUPPORT

87       Support is offered through the "datetime@perl.org" mailing list.
88
89       Please report bugs using rt.cpan.org
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AUTHOR

92       Flavio Soibelmann Glock <fglock@pucrs.br>
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94       The recurrence generation algorithm is based on an idea from Dave Rol‐
95       sky.
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COPYRIGHT

98       Copyright (c) 2003 Flavio Soibelmann Glock. All rights reserved.  This
99       program is free software; you can distribute it and/or modify it under
100       the same terms as Perl itself.
101
102       The full text of the license can be found in the LICENSE file included
103       with this module.
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