perl 5.000perl-5.000

[editor's note: this commit combines approximate 4 months of furious
releases of Andy Dougherty and Larry Wall - see pod/perlhist.pod for
details.  Andy notes that;
 
Alas neither my "Irwin AccuTrack" nor my DC 600A quarter-inch cartridge 
backup tapes from that era seem to be readable anymore.  I guess 13 years 
exceeds the shelf life for that backup technology :-(.
]

1 files changed, 105 insertions, 0 deletions

diff --git a/lib/Time/Local.pm b/lib/Time/Local.pm
new file mode 100644
index 0000000000..64e62405f7
--- /dev/null
+++ b/lib/Time/Local.pm
@@ -0,0 +1,105 @@
+package Time::Local;
+require 5.000;
+require Exporter;
+use Carp;
+
+@ISA = qw(Exporter);
+@EXPORT = qw(timegm timelocal);
+
+# timelocal.pl
+#
+# Usage:
+#	$time = timelocal($sec,$min,$hours,$mday,$mon,$year);
+#	$time = timegm($sec,$min,$hours,$mday,$mon,$year);
+
+# These routines are quite efficient and yet are always guaranteed to agree
+# with localtime() and gmtime().  We manage this by caching the start times
+# of any months we've seen before.  If we know the start time of the month,
+# we can always calculate any time within the month.  The start times
+# themselves are guessed by successive approximation starting at the
+# current time, since most dates seen in practice are close to the
+# current date.  Unlike algorithms that do a binary search (calling gmtime
+# once for each bit of the time value, resulting in 32 calls), this algorithm
+# calls it at most 6 times, and usually only once or twice.  If you hit
+# the month cache, of course, it doesn't call it at all.
+
+# timelocal is implemented using the same cache.  We just assume that we're
+# translating a GMT time, and then fudge it when we're done for the timezone
+# and daylight savings arguments.  The timezone is determined by examining
+# the result of localtime(0) when the package is initialized.  The daylight
+# savings offset is currently assumed to be one hour.
+
+# Both routines return -1 if the integer limit is hit. I.e. for dates
+# after the 1st of January, 2038 on most machines.
+
+@epoch = localtime(0);
+$tzmin = $epoch[2] * 60 + $epoch[1];	# minutes east of GMT
+if ($tzmin > 0) {
+    $tzmin = 24 * 60 - $tzmin;		# minutes west of GMT
+    $tzmin -= 24 * 60 if $epoch[5] == 70;	# account for the date line
+}
+
+$SEC = 1;
+$MIN = 60 * $SEC;
+$HR = 60 * $MIN;
+$DAYS = 24 * $HR;
+$YearFix = ((gmtime(946684800))[5] == 100) ? 100 : 0;
+
+sub timegm {
+    $ym = pack(C2, @_[5,4]);
+    $cheat = $cheat{$ym} || &cheat;
+    return -1 if $cheat<0;
+    $cheat + $_[0] * $SEC + $_[1] * $MIN + $_[2] * $HR + ($_[3]-1) * $DAYS;
+}
+
+sub timelocal {
+    $time = &timegm + $tzmin*$MIN;
+    return -1 if $cheat<0;
+    @test = localtime($time);
+    $time -= $HR if $test[2] != $_[2];
+    $time;
+}
+
+sub cheat {
+    $year = $_[5];
+    $month = $_[4];
+    croak "Month out of range 0..11 in timelocal.pl" 
+	if $month > 11 || $month < 0;
+    croak "Day out of range 1..31 in timelocal.pl" 
+	if $_[3] > 31 || $_[3] < 1;
+    croak "Hour out of range 0..23 in timelocal.pl"
+	if $_[2] > 23 || $_[2] < 0;
+    croak "Minute out of range 0..59 in timelocal.pl"
+	if $_[1] > 59 || $_[1] < 0;
+    croak "Second out of range 0..59 in timelocal.pl"
+	if $_[0] > 59 || $_[0] < 0;
+    $guess = $^T;
+    @g = gmtime($guess);
+    $year += $YearFix if $year < $epoch[5];
+    $lastguess = "";
+    while ($diff = $year - $g[5]) {
+	$guess += $diff * (363 * $DAYS);
+	@g = gmtime($guess);
+	if (($thisguess = "@g") eq $lastguess){
+	    return -1; #date beyond this machine's integer limit
+	}
+	$lastguess = $thisguess;
+    }
+    while ($diff = $month - $g[4]) {
+	$guess += $diff * (27 * $DAYS);
+	@g = gmtime($guess);
+	if (($thisguess = "@g") eq $lastguess){
+	    return -1; #date beyond this machine's integer limit
+	}
+	$lastguess = $thisguess;
+    }
+    @gfake = gmtime($guess-1); #still being sceptic
+    if ("@gfake" eq $lastguess){
+	return -1; #date beyond this machine's integer limit
+    }
+    $g[3]--;
+    $guess -= $g[0] * $SEC + $g[1] * $MIN + $g[2] * $HR + $g[3] * $DAYS;
+    $cheat{$ym} = $guess;
+}
+
+1;