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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;