path: root/ext/Time/Piece/Piece.pm

package Time::Piece;

use strict;
use vars qw($VERSION @ISA @EXPORT %EXPORT_TAGS);

require Exporter;
require DynaLoader;
use Time::Seconds;
use Carp;
use UNIVERSAL;

@ISA = qw(Exporter DynaLoader);

@EXPORT = qw(
    localtime
    gmtime
);

%EXPORT_TAGS = ( 
        ':override' => 'internal',
        );

$VERSION = '0.13';

bootstrap Time::Piece $VERSION;

my $DATE_SEP = '-';
my $TIME_SEP = ':';
my @MON_LIST;
my @DAY_LIST;

use constant 'c_sec' => 0;
use constant 'c_min' => 1;
use constant 'c_hour' => 2;
use constant 'c_mday' => 3;
use constant 'c_mon' => 4;
use constant 'c_year' => 5;
use constant 'c_wday' => 6;
use constant 'c_yday' => 7;
use constant 'c_isdst' => 8;
use constant 'c_epoch' => 9;
use constant 'c_islocal' => 10;

sub localtime {
    my $time = shift;
    $time = time if (!defined $time);
    _mktime($time, 1);
}

sub gmtime {
    my $time = shift;
    $time = time if (!defined $time);
    _mktime($time, 0);
}

sub new {
    my $proto = shift;
    my $class = ref($proto) || $proto;
    my $time = shift;
    
    my $self;
    
    if (defined($time)) {
        $self = &localtime($time);
    }
    elsif (ref($proto) && $proto->isa('Time::Piece')) {
        $self = _mktime($proto->[c_epoch], $proto->[c_islocal]);
    }
    else {
        $self = &localtime();
    }
    
    return bless $self, $class;
}

sub _mktime {
    my ($time, $islocal) = @_;
    my @time = $islocal ? 
            CORE::localtime($time)
            :
            CORE::gmtime($time);
    wantarray ? @time : bless [@time, $time, $islocal], 'Time::Piece';
}

sub import {
    # replace CORE::GLOBAL localtime and gmtime if required
    my $class = shift;
    my %params;
    map($params{$_}++,@_,@EXPORT);
    if (delete $params{':override'}) {
        $class->export('CORE::GLOBAL', keys %params);
    }
    else {
        $class->export((caller)[0], keys %params);
    }
}

## Methods ##

sub sec {
    my $time = shift;
    $time->[c_sec];
}

*second = \&sec;

sub min {
    my $time = shift;
    $time->[c_min];
}

*minute = \&minute;

sub hour {
    my $time = shift;
    $time->[c_hour];
}

sub mday {
    my $time = shift;
    $time->[c_mday];
}

*day_of_month = \&mday;

sub mon {
    my $time = shift;
    $time->[c_mon] + 1;
}

sub _mon {
    my $time = shift;
    $time->[c_mon];
}

sub month {
    my $time = shift;
    if (@_) {
        return $_[$time->[c_mon]];
    }
    elsif (@MON_LIST) {
        return $MON_LIST[$time->[c_mon]];
    }
    else {
        return $time->strftime('%B');
    }
}

sub year {
    my $time = shift;
    $time->[c_year] + 1900;
}

sub _year {
    my $time = shift;
    $time->[c_year];
}

sub wday {
    my $time = shift;
    $time->[c_wday] + 1;
}

sub _wday {
    my $time = shift;
    $time->[c_wday];
}

*day_of_week = \&_wday;

sub wdayname {
    my $time = shift;
    if (@_) {
        return $_[$time->[c_wday]];
    }
    elsif (@DAY_LIST) {
        return $DAY_LIST[$time->[c_wday]];
    }
    else {
        return $time->strftime('%A');
    }
}

*day = \&wdayname;

sub yday {
    my $time = shift;
    $time->[c_yday];
}

*day_of_year = \&yday;

sub isdst {
    my $time = shift;
    $time->[c_isdst];
}

*daylight_savings = \&isdst;

# Thanks to Tony Olekshy <olekshy@cs.ualberta.ca> for this algorithm
sub tzoffset {
    my $time = shift;

    my $epoch = $time->[c_epoch];

    my $j = sub { # Tweaked Julian day number algorithm.

        my ($s,$n,$h,$d,$m,$y) = @_; $m += 1; $y += 1900;

        # Standard Julian day number algorithm without constant.
        #
        my $y1 = $m > 2 ? $y : $y - 1;

        my $m1 = $m > 2 ? $m + 1 : $m + 13;

        my $day = int(365.25 * $y1) + int(30.6001 * $m1) + $d;

        # Modify to include hours/mins/secs in floating portion.
        #
        return $day + ($h + ($n + $s / 60) / 60) / 24;
    };

    # Compute floating offset in hours.
    #
    my $delta = 24 * (&$j(CORE::localtime $epoch) - &$j(CORE::gmtime $epoch));

    # Return value in seconds rounded to nearest minute.
    return Time::Seconds->new( int($delta * 60 + ($delta >= 0 ? 0.5 : -0.5)) * 60);
}

sub epoch {
    my $time = shift;
    $time->[c_epoch];
}

sub hms {
    my $time = shift;
    my $sep = shift || $TIME_SEP;
    sprintf("%02d$sep%02d$sep%02d", $time->[c_hour], $time->[c_min], $time->[c_sec]);
}

*time = \&hms;

sub ymd {
    my $time = shift;
    my $sep = shift || $DATE_SEP;
    sprintf("%d$sep%02d$sep%02d", $time->year, $time->mon, $time->[c_mday]);
}

*date = \&ymd;

sub mdy {
    my $time = shift;
    my $sep = shift || $DATE_SEP;
    sprintf("%02d$sep%02d$sep%d", $time->mon, $time->[c_mday], $time->year);
}

sub dmy {
    my $time = shift;
    my $sep = shift || $DATE_SEP;
    sprintf("%02d$sep%02d$sep%d", $time->[c_mday], $time->mon, $time->year);
}

sub datetime {
    my $time = shift;
    my $dsep = shift || $DATE_SEP;
    my $tsep = shift || $TIME_SEP;
    return join('T', $time->date($dsep), $time->time($tsep));
}

# taken from Time::JulianDay
sub julian_day {
    my $time = shift;
    my ($year, $month, $day) = ($time->year, $time->mon, $time->mday);
    my ($tmp, $secs);

    $tmp = $day - 32075
      + 1461 * ( $year + 4800 - ( 14 - $month ) / 12 )/4
      + 367 * ( $month - 2 + ( ( 14 - $month ) / 12 ) * 12 ) / 12
      - 3 * ( ( $year + 4900 - ( 14 - $month ) / 12 ) / 100 ) / 4
      ;

    return $tmp;
}

# Hi Mark Jason!
sub mjd {
    # taken from the Calendar FAQ
    return shift->julian_day - 2_400_000.5;
}

sub strftime {
    my $time = shift;
    my $format = shift || "%a, %d %b %Y %H:%M:%S %Z";
    return _strftime($format, (@$time)[c_sec..c_isdst]);
}

sub day_list {
    shift if ref($_[0]) && $_[0]->isa(__PACKAGE__); # strip first if called as a method
    my @old = @DAY_LIST;
    if (@_) {
        @DAY_LIST = @_;
    }
    return @old;
}

sub mon_list {
    shift if ref($_[0]) && $_[0]->isa(__PACKAGE__); # strip first if called as a method
    my @old = @MON_LIST;
    if (@_) {
        @MON_LIST = @_;
    }
    return @old;
}

sub time_separator {
    shift if ref($_[0]) && $_[0]->isa(__PACKAGE__);
    my $old = $TIME_SEP;
    if (@_) {
        $TIME_SEP = $_[0];
    }
    return $old;
}

sub date_separator {
    shift if ref($_[0]) && $_[0]->isa(__PACKAGE__);
    my $old = $DATE_SEP;
    if (@_) {
        $DATE_SEP = $_[0];
    }
    return $old;
}

use overload '""' => \&cdate;

sub cdate {
    my $time = shift;
    if ($time->[c_islocal]) {
        return scalar(CORE::localtime($time->[c_epoch]));
    }
    else {
        return scalar(CORE::gmtime($time->[c_epoch]));
    }
}

use overload
        '-' => \&subtract,
        '+' => \&add;

sub subtract {
    my $time = shift;
    my $rhs = shift;
    die "Can't subtract a date from something!" if shift;
    
    if (ref($rhs) && $rhs->isa('Time::Piece')) {
        return Time::Seconds->new($time->[c_epoch] - $rhs->epoch);
    }
    else {
        # rhs is seconds.
        return _mktime(($time->[c_epoch] - $rhs), $time->[c_islocal]);
    }
}

sub add {
    warn "add\n";
    my $time = shift;
    my $rhs = shift;
    croak "Invalid rhs of addition: $rhs" if ref($rhs);
    
    return _mktime(($time->[c_epoch] + $rhs), $time->[c_islocal]);
}

use overload
        '<=>' => \&compare;

sub get_epochs {
    my ($time, $rhs, $reverse) = @_;
    $time = $time->epoch;
    if (UNIVERSAL::isa($rhs, 'Time::Piece')) {
        $rhs = $rhs->epoch;
    }
    if ($reverse) {
        return $rhs, $time;
    }
    return $time, $rhs;
}

sub compare {
    my ($lhs, $rhs) = get_epochs(@_);
    return $lhs <=> $rhs;
}

1;
__END__

=head1 NAME

Time::Piece - Object Oriented time objects

=head1 SYNOPSIS

    use Time::Piece;
    
    my $t = localtime;
    print "Time is $t\n";
    print "Year is ", $t->year, "\n";

=head1 DESCRIPTION

This module replaces the standard localtime and gmtime functions with
implementations that return objects. It does so in a backwards
compatible manner, so that using localtime/gmtime in the way documented
in perlfunc will still return what you expect.

The module actually implements most of an interface described by
Larry Wall on the perl5-porters mailing list here:
http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2000-01/msg00241.html

=head1 USAGE

After importing this module, when you use localtime or gmtime in a scalar
context, rather than getting an ordinary scalar string representing the
date and time, you get a Time::Piece object, whose stringification happens
to produce the same effect as the localtime and gmtime functions. There is 
also a new() constructor provided, which is the same as localtime(), except
when passed a Time::Piece object, in which case it's a copy constructor. The
following methods are available on the object:

    $t->sec               # also available as $t->second
    $t->min               # also available as $t->minute
    $t->hour
    $t->mday              # also available as $t->day_of_month
    $t->mon               # based at 1
    $t->_mon              # based at 0
    $t->monname           # February
    $t->month             # same as $t->monname
    $t->year              # based at 0 (year 0 AD is, of course 1 BC).
    $t->_year             # year minus 1900
    $t->wday              # based at 1 = Sunday
    $t->_wday             # based at 0 = Sunday
    $t->day_of_week       # based at 0 = Sunday
    $t->wdayname          # Tuesday
    $t->day               # same as wdayname
    $t->yday              # also available as $t->day_of_year
    $t->isdst             # also available as $t->daylight_savings
    $t->hms               # 01:23:45
    $t->time              # same as $t->hms
    $t->ymd               # 2000-02-29
    $t->date              # same as $t->ymd
    $t->mdy               # 02-29-2000
    $t->dmy               # 29-02-2000
    $t->cdate             # Tue Feb 29 01:23:45 2000
    "$t"                  # same as $t->cdate
    $t->epoch             # seconds since the epoch
    $t->tzoffset          # timezone offset in a Time::Seconds object
    $t->julian_day        # number of days since julian calendar began
    $t->mjd               # modified julian day
    $t->strftime(FORMAT)  # same as POSIX::strftime (without POSIX.pm)

=head2 Local Locales

Both wdayname (day) and monname (month) allow passing in a list to use to
index the name of the days against. This can be useful if you need to
implement some form of localisation without actually installing locales.

  my @days = qw( Dimanche Lundi Merdi Mercredi Jeudi Vendredi Samedi );
  
  my $french_day = localtime->day(@days);

These settings can be overriden globally too:

  Time::Piece::day_list(@days);

Or for months:

  Time::Piece::mon_list(@months);

And locally for months:

  print localtime->month(@months);

=head2 Date Calculations

It's possible to use simple addition and subtraction of objects:

    use Time::Seconds;
    
    my $seconds = $t1 - $t2;
    $t1 += ONE_DAY; # add 1 day (constant from Time::Seconds)

The following are valid ($t1 and $t2 are Time::Piece objects):

    $t1 - $t2; # returns Time::Seconds object
    $t1 - 42; # returns Time::Piece object
    $t1 + 533; # returns Time::Piece object

However adding a Time::Piece object to another Time::Piece object
will cause a runtime error.

Note that the first of the above returns a Time::Seconds object, so
while examining the object will print the number of seconds (because
of the overloading), you can also get the number of minutes, hours,
days, weeks and years in that delta, using the Time::Seconds API.

=head2 Date Comparisons

Date comparisons are also possible, using the full suite of "<", ">",
"<=", ">=", "<=>", "==" and "!=".

=head2 Global Overriding

Finally, it's possible to override localtime and gmtime everywhere, by
including the ':override' tag in the import list:

    use Time::Piece ':override';

=head1 AUTHOR

Matt Sergeant, matt@sergeant.org

This module is based on Time::Piece, with changes suggested by Jarkko
Hietaniemi before including in core perl.

=head2 License

This module is free software, you may distribute it under the same terms
as Perl.

=head2 Bugs

The test harness leaves much to be desired. Patches welcome.

=cut