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| Current File : //lib64/perl5/vendor_perl/DateTime/LeapSecond.pm |
package DateTime::LeapSecond;
{
$DateTime::LeapSecond::VERSION = '1.04';
}
use strict;
use warnings;
use vars qw( @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 . " ", $op );
$tmp .= "${tab}}\n";
$tmp .= "${tab}else {\n";
$tmp .= _make_utx( $beg + $step, $end, $tab . " ", $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";
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, " ", "+" );
$tmp .= "}\n";
# NOTE: uncomment the line below to see the code:
#warn $tmp;
eval $tmp;
}
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 Jun. 1 +1
2015 Jul. 1 +1
2017 Jan. 1 +1
)
);
}
__PACKAGE__->_initialize();
1;
# ABSTRACT: leap seconds table and utilities
__END__
=pod
=head1 NAME
DateTime::LeapSecond - leap seconds table and utilities
=head1 VERSION
version 1.04
=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 DateTime.pm cannot compile the XS version of
this code.
This library is known to be accurate for dates until December 2009.
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,
in the range 0 .. 22.
=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
E<lt>http://hpiers.obspm.fr/eop-pc/earthor/utc/leapsecond.htmlE<gt>
http://datetime.perl.org
=head1 AUTHOR
Dave Rolsky <autarch@urth.org>
=head1 COPYRIGHT AND LICENSE
This software is Copyright (c) 2013 by Dave Rolsky.
This is free software, licensed under:
The Artistic License 2.0 (GPL Compatible)
=cut