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package Time::Zone;
=head1 NAME
Time::Zone -- miscellaneous timezone manipulations routines
=head1 SYNOPSIS
use Time::Zone;
print tz2zone();
print tz2zone($ENV{'TZ'});
print tz2zone($ENV{'TZ'}, time());
print tz2zone($ENV{'TZ'}, undef, $isdst);
$offset = tz_local_offset();
$offset = tz_offset($TZ);
=head1 DESCRIPTION
This is a collection of miscellaneous timezone manipulation routines.
C<tz2zone()> parses the TZ environment variable and returns a timezone
string suitable for inclusion in L<date(1)>-like output. It opionally takes
a timezone string, a time, and a is-dst flag.
C<tz_local_offset()> determins the offset from GMT time in seconds. It
only does the calculation once.
C<tz_offset()> determines the offset from GMT in seconds of a specified
timezone.
C<tz_name()> determines the name of the timezone based on its offset
=head1 AUTHORS
Graham Barr <gbarr@pobox.com>
David Muir Sharnoff <muir@idiom.com>
Paul Foley <paul@ascent.com>
=cut
require 5.002;
require Exporter;
use Carp;
use strict;
use vars qw(@ISA @EXPORT $VERSION @tz_local);
@ISA = qw(Exporter);
@EXPORT = qw(tz2zone tz_local_offset tz_offset tz_name);
$VERSION = "2.24";
# Parts stolen from code by Paul Foley <paul@ascent.com>
sub tz2zone (;$$$)
{
my($TZ, $time, $isdst) = @_;
use vars qw(%tzn_cache);
$TZ = defined($ENV{'TZ'}) ? ( $ENV{'TZ'} ? $ENV{'TZ'} : 'GMT' ) : ''
unless $TZ;
# Hack to deal with 'PST8PDT' format of TZ
# Note that this can't deal with all the esoteric forms, but it
# does recognize the most common: [:]STDoff[DST[off][,rule]]
if (! defined $isdst) {
my $j;
$time = time() unless $time;
($j, $j, $j, $j, $j, $j, $j, $j, $isdst) = localtime($time);
}
if (defined $tzn_cache{$TZ}->[$isdst]) {
return $tzn_cache{$TZ}->[$isdst];
}
if ($TZ =~ /^
( [^:\d+\-,] {3,} )
( [+-] ?
\d {1,2}
( : \d {1,2} ) {0,2}
)
( [^\d+\-,] {3,} )?
/x
) {
my $dsttz = defined($4) ? $4 : $1;
$TZ = $isdst ? $dsttz : $1;
$tzn_cache{$TZ} = [ $1, $dsttz ];
} else {
$tzn_cache{$TZ} = [ $TZ, $TZ ];
}
return $TZ;
}
sub tz_local_offset (;$)
{
my ($time) = @_;
$time = time() unless $time;
my (@l) = localtime($time);
my $isdst = $l[8];
if (defined($tz_local[$isdst])) {
return $tz_local[$isdst];
}
$tz_local[$isdst] = &calc_off($time);
return $tz_local[$isdst];
}
sub calc_off
{
my ($time) = @_;
my (@l) = localtime($time);
my (@g) = gmtime($time);
my $off;
$off = $l[0] - $g[0]
+ ($l[1] - $g[1]) * 60
+ ($l[2] - $g[2]) * 3600;
# subscript 7 is yday.
if ($l[7] == $g[7]) {
# done
} elsif ($l[7] == $g[7] + 1) {
$off += 86400;
} elsif ($l[7] == $g[7] - 1) {
$off -= 86400;
} elsif ($l[7] < $g[7]) {
# crossed over a year boundry!
# localtime is beginning of year, gmt is end
# therefore local is ahead
$off += 86400;
} else {
$off -= 86400;
}
return $off;
}
# constants
CONFIG: {
use vars qw(%dstZone %zoneOff %dstZoneOff %Zone);
my @dstZone = (
# "ndt" => -2*3600-1800, # Newfoundland Daylight
"brst" => -2*3600, # Brazil Summer Time (East Daylight)
"adt" => -3*3600, # Atlantic Daylight
"edt" => -4*3600, # Eastern Daylight
"cdt" => -5*3600, # Central Daylight
"mdt" => -6*3600, # Mountain Daylight
"pdt" => -7*3600, # Pacific Daylight
"akdt" => -8*3600, # Alaska Daylight
"ydt" => -8*3600, # Yukon Daylight
"hdt" => -9*3600, # Hawaii Daylight
"bst" => +1*3600, # British Summer
"mest" => +2*3600, # Middle European Summer
"metdst" => +2*3600, # Middle European DST
"sst" => +2*3600, # Swedish Summer
"fst" => +2*3600, # French Summer
"cest" => +2*3600, # Central European Daylight
"eest" => +3*3600, # Eastern European Summer
"msd" => +4*3600, # Moscow Daylight
"wadt" => +8*3600, # West Australian Daylight
"kdt" => +10*3600, # Korean Daylight
# "cadt" => +10*3600+1800, # Central Australian Daylight
"aedt" => +11*3600, # Eastern Australian Daylight
"eadt" => +11*3600, # Eastern Australian Daylight
"nzd" => +13*3600, # New Zealand Daylight
"nzdt" => +13*3600, # New Zealand Daylight
);
my @Zone = (
"gmt" => 0, # Greenwich Mean
"ut" => 0, # Universal (Coordinated)
"utc" => 0,
"wet" => 0, # Western European
"wat" => -1*3600, # West Africa
"at" => -2*3600, # Azores
"fnt" => -2*3600, # Brazil Time (Extreme East - Fernando Noronha)
"brt" => -3*3600, # Brazil Time (East Standard - Brasilia)
# For completeness. BST is also British Summer, and GST is also Guam Standard.
# "bst" => -3*3600, # Brazil Standard
# "gst" => -3*3600, # Greenland Standard
# "nft" => -3*3600-1800,# Newfoundland
# "nst" => -3*3600-1800,# Newfoundland Standard
"mnt" => -4*3600, # Brazil Time (West Standard - Manaus)
"ewt" => -4*3600, # U.S. Eastern War Time
"ast" => -4*3600, # Atlantic Standard
"est" => -5*3600, # Eastern Standard
"act" => -5*3600, # Brazil Time (Extreme West - Acre)
"cst" => -6*3600, # Central Standard
"mst" => -7*3600, # Mountain Standard
"pst" => -8*3600, # Pacific Standard
"akst" => -9*3600, # Alaska Standard
"yst" => -9*3600, # Yukon Standard
"hst" => -10*3600, # Hawaii Standard
"cat" => -10*3600, # Central Alaska
"ahst" => -10*3600, # Alaska-Hawaii Standard
"nt" => -11*3600, # Nome
"idlw" => -12*3600, # International Date Line West
"cet" => +1*3600, # Central European
"mez" => +1*3600, # Central European (German)
"ect" => +1*3600, # Central European (French)
"met" => +1*3600, # Middle European
"mewt" => +1*3600, # Middle European Winter
"swt" => +1*3600, # Swedish Winter
"set" => +1*3600, # Seychelles
"fwt" => +1*3600, # French Winter
"eet" => +2*3600, # Eastern Europe, USSR Zone 1
"ukr" => +2*3600, # Ukraine
"bt" => +3*3600, # Baghdad, USSR Zone 2
"msk" => +3*3600, # Moscow
# "it" => +3*3600+1800,# Iran
"zp4" => +4*3600, # USSR Zone 3
"zp5" => +5*3600, # USSR Zone 4
# "ist" => +5*3600+1800,# Indian Standard
"zp6" => +6*3600, # USSR Zone 5
# For completeness. NST is also Newfoundland Stanard, and SST is also Swedish Summer.
# "nst" => +6*3600+1800,# North Sumatra
# "sst" => +7*3600, # South Sumatra, USSR Zone 6
# "jt" => +7*3600+1800,# Java (3pm in Cronusland!)
"wst" => +8*3600, # West Australian Standard
"hkt" => +8*3600, # Hong Kong
"cct" => +8*3600, # China Coast, USSR Zone 7
"jst" => +9*3600, # Japan Standard, USSR Zone 8
"kst" => +9*3600, # Korean Standard
# "cast" => +9*3600+1800,# Central Australian Standard
"aest" => +10*3600, # Eastern Australian Standard
"east" => +10*3600, # Eastern Australian Standard
"gst" => +10*3600, # Guam Standard, USSR Zone 9
"nzt" => +12*3600, # New Zealand
"nzst" => +12*3600, # New Zealand Standard
"idle" => +12*3600, # International Date Line East
);
%Zone = @Zone;
%dstZone = @dstZone;
%zoneOff = reverse(@Zone);
%dstZoneOff = reverse(@dstZone);
}
sub tz_offset (;$$)
{
my ($zone, $time) = @_;
return &tz_local_offset($time) unless($zone);
$time = time() unless $time;
my(@l) = localtime($time);
my $dst = $l[8];
$zone = lc $zone;
if($zone =~ /^(([\-\+])\d\d?)(\d\d)$/) {
my $v = $2 . $3;
return $1 * 3600 + $v * 60;
} elsif (exists $dstZone{$zone} && ($dst || !exists $Zone{$zone})) {
return $dstZone{$zone};
} elsif(exists $Zone{$zone}) {
return $Zone{$zone};
}
undef;
}
sub tz_name (;$$)
{
my ($off, $dst) = @_;
$off = tz_offset()
unless(defined $off);
$dst = (localtime(time))[8]
unless(defined $dst);
if (exists $dstZoneOff{$off} && ($dst || !exists $zoneOff{$off})) {
return $dstZoneOff{$off};
} elsif (exists $zoneOff{$off}) {
return $zoneOff{$off};
}
sprintf("%+05d", int($off / 60) * 100 + $off % 60);
}
1;
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