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Edit File: LeapSecond.pm
package DateTime::LeapSecond; use strict; use warnings; use namespace::autoclean; our $VERSION = '1.59'; our ( @RD, @LEAP_SECONDS, %RD_LENGTH ); use DateTime; # Generates a Perl binary decision tree sub _make_utx { my ( $beg, $end, $tab, $op ) = @_; my $step = int( ( $end - $beg ) / 2 ); my $tmp; if ( $step <= 0 ) { $tmp = "${tab}return $LEAP_SECONDS[$beg + 1];\n"; return $tmp; } $tmp = "${tab}if (\$val < " . $RD[ $beg + $step ] . ") {\n"; $tmp .= _make_utx( $beg, $beg + $step, $tab . q{ }, $op ); $tmp .= "${tab}}\n"; $tmp .= "${tab}else {\n"; $tmp .= _make_utx( $beg + $step, $end, $tab . q{ }, $op ); $tmp .= "${tab}}\n"; return $tmp; } # Process BEGIN data and write binary tree decision table sub _init { my $value = -1; while (@_) { my ( $year, $mon, $mday, $leap_seconds ) = ( shift, shift, shift, shift ); # print "$year,$mon,$mday\n"; ## no critic (Subroutines::ProtectPrivateSubs) my $utc_epoch = DateTime->_ymd2rd( $year, ( $mon =~ /Jan/i ? 1 : 7 ), $mday ); $value++; push @LEAP_SECONDS, $value; push @RD, $utc_epoch; $RD_LENGTH{ $utc_epoch - 1 } = $leap_seconds; # warn "$year,$mon,$mday = $utc_epoch +$value"; } push @LEAP_SECONDS, ++$value; my $tmp; # write binary tree decision table $tmp = "sub leap_seconds {\n"; $tmp .= " my \$val = shift;\n"; $tmp .= _make_utx( -1, 1 + $#RD, q{ }, '+' ); $tmp .= "}; 1\n"; # NOTE: uncomment the line below to see the code: #warn $tmp; ## no critic (BuiltinFunctions::ProhibitStringyEval) eval $tmp or die $@; } sub extra_seconds { exists $RD_LENGTH{ $_[0] } ? $RD_LENGTH{ $_[0] } : 0; } sub day_length { exists $RD_LENGTH{ $_[0] } ? 86400 + $RD_LENGTH{ $_[0] } : 86400; } sub _initialize { # There are no leap seconds before 1972, because that's the # year this system was implemented. # # year month day number-of-leapseconds # _init( qw( 1972 Jul. 1 +1 1973 Jan. 1 +1 1974 Jan. 1 +1 1975 Jan. 1 +1 1976 Jan. 1 +1 1977 Jan. 1 +1 1978 Jan. 1 +1 1979 Jan. 1 +1 1980 Jan. 1 +1 1981 Jul. 1 +1 1982 Jul. 1 +1 1983 Jul. 1 +1 1985 Jul. 1 +1 1988 Jan. 1 +1 1990 Jan. 1 +1 1991 Jan. 1 +1 1992 Jul. 1 +1 1993 Jul. 1 +1 1994 Jul. 1 +1 1996 Jan. 1 +1 1997 Jul. 1 +1 1999 Jan. 1 +1 2006 Jan. 1 +1 2009 Jan. 1 +1 2012 Jul. 1 +1 2015 Jul. 1 +1 2017 Jan. 1 +1 ) ); } __PACKAGE__->_initialize(); 1; # ABSTRACT: leap seconds table and utilities __END__ =pod =encoding UTF-8 =head1 NAME DateTime::LeapSecond - leap seconds table and utilities =head1 VERSION version 1.59 =head1 SYNOPSIS use DateTime; use DateTime::LeapSecond; print "Leap seconds between years 1990 and 2000 are "; print DateTime::Leapsecond::leap_seconds($utc_rd_2000) - DateTime::Leapsecond::leap_seconds($utc_rd_1990); =head1 DESCRIPTION This module is used to calculate leap seconds for a given Rata Die day. It is used when L<DateTime> cannot compile the XS version of this code. This library is known to be accurate for dates until Jun 2020. There are no leap seconds before 1972, because that's the year this system was implemented. =over 4 =item * leap_seconds($rd) Returns the number of accumulated leap seconds for a given day. =item * extra_seconds($rd) Returns the number of leap seconds for a given day, in the range -2 .. 2. =item * day_length($rd) Returns the number of seconds for a given day, in the range 86398 .. 86402. =back =head1 SEE ALSO L<http://hpiers.obspm.fr/eop-pc/earthor/utc/leapsecond.html> =head1 SUPPORT Bugs may be submitted at L<https://github.com/houseabsolute/DateTime.pm/issues>. There is a mailing list available for users of this distribution, L<mailto:datetime@perl.org>. =head1 SOURCE The source code repository for DateTime can be found at L<https://github.com/houseabsolute/DateTime.pm>. =head1 AUTHOR Dave Rolsky <autarch@urth.org> =head1 COPYRIGHT AND LICENSE This software is Copyright (c) 2003 - 2022 by Dave Rolsky. This is free software, licensed under: The Artistic License 2.0 (GPL Compatible) The full text of the license can be found in the F<LICENSE> file included with this distribution. =cut