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
17       ability to define recurrences with arbitrary objects, such as dates.
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METHODS

20       ·   _recurrence ( \&next, \&previous )
21
22           Creates a recurrence set. The set is defined inside a 'base set'.
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24              $recurrence = $base_set->_recurrence ( \&next, \&previous );
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26           The recurrence functions take one argument, and return the 'next'
27           or the 'previous' occurence.
28
29           Example: defines the set of all 'integer numbers':
30
31               use strict;
32
33               use Set::Infinite::_recurrence;
34               use POSIX qw(floor);
35
36               # define the recurrence span
37               my $forever = Set::Infinite::_recurrence->new(
38                   Set::Infinite::_recurrence::NEG_INFINITY,
39                   Set::Infinite::_recurrence::INFINITY
40               );
41
42               my $recurrence = $forever->_recurrence(
43                   sub {   # next
44                           floor( $_[0] + 1 )
45                       },
46                   sub {   # previous
47                           my $tmp = floor( $_[0] );
48                           $tmp < $_[0] ? $tmp : $_[0] - 1
49                       },
50               );
51
52               print "sample recurrence ",
53                     $recurrence->intersection( -5, 5 ), "\n";
54               # sample recurrence -5,-4,-3,-2,-1,0,1,2,3,4,5
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56               {
57                   my $x = 234.567;
58                   print "next occurence after $x = ",
59                         $recurrence->{param}[0]->( $x ), "\n";  # 235
60                   print "previous occurence before $x = ",
61                         $recurrence->{param}[2]->( $x ), "\n";  # 234
62               }
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64               {
65                   my $x = 234;
66                   print "next occurence after $x = ",
67                         $recurrence->{param}[0]->( $x ), "\n";  # 235
68                   print "previous occurence before $x = ",
69                         $recurrence->{param}[2]->( $x ), "\n";  # 233
70               }
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72       ·   is_forever
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74           Returns true if the set is a single span, ranging from -Infinity to
75           Infinity.
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77       ·   _is_recurrence
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79           Returns true if the set is an unbounded recurrence, ranging from
80           -Infinity to Infinity.
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CONSTANTS

83       ·   INFINITY
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85           The "Infinity" value.
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87       ·   NEG_INFINITY
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89           The "-Infinity" value.
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SUPPORT

92       Support is offered through the "datetime@perl.org" mailing list.
93
94       Please report bugs using rt.cpan.org
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AUTHOR

97       Flavio Soibelmann Glock <fglock@pucrs.br>
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99       The recurrence generation algorithm is based on an idea from Dave
100       Rolsky.
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COPYRIGHT

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