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package Sort::Versions;
$Sort::Versions::VERSION = '1.62';
# Copyright (c) 1996, Kenneth J. Albanowski. All rights reserved.  This
# program is free software; you can redistribute it and/or modify it under
# the same terms as Perl itself.

use 5.006;
use strict;
use warnings;

require Exporter;
our @ISA        = qw(Exporter);
our @EXPORT     = qw(&versions &versioncmp);
our @EXPORT_OK  = qw();

sub versioncmp ($$) {
    my @A = ($_[0] =~ /([-.]|\d+|[^-.\d]+)/g);
    my @B = ($_[1] =~ /([-.]|\d+|[^-.\d]+)/g);

    my ($A, $B);
    while (@A and @B) {
	$A = shift @A;
	$B = shift @B;
	if ($A eq '-' and $B eq '-') {
	    next;
	} elsif ( $A eq '-' ) {
	    return -1;
	} elsif ( $B eq '-') {
	    return 1;
	} elsif ($A eq '.' and $B eq '.') {
	    next;
	} elsif ( $A eq '.' ) {
	    return -1;
	} elsif ( $B eq '.' ) {
	    return 1;
	} elsif ($A =~ /^\d+$/ and $B =~ /^\d+$/) {
	    if ($A =~ /^0/ || $B =~ /^0/) {
		return $A cmp $B if $A cmp $B;
	    } else {
		return $A <=> $B if $A <=> $B;
	    }
	} else {
	    $A = uc $A;
	    $B = uc $B;
	    return $A cmp $B if $A cmp $B;
	}	
    }
    @A <=> @B;
}

sub versions () {
    my $callerpkg = (caller)[0];
    my $caller_a = "${callerpkg}::a";
    my $caller_b = "${callerpkg}::b";
    no strict 'refs';
    return versioncmp($$caller_a, $$caller_b);
}

=encoding utf-8

=head1 NAME

Sort::Versions - a perl 5 module for sorting of revision-like numbers

=head1 SYNOPSIS

	use Sort::Versions;
	@l = sort { versioncmp($a, $b) } qw( 1.2 1.2.0 1.2a.0 1.2.a 1.a 02.a );

	...

	use Sort::Versions;
	print 'lower' if versioncmp('1.2', '1.2a') == -1;

	...

	use Sort::Versions;
	%h = (1 => 'd', 2 => 'c', 3 => 'b', 4 => 'a');
	@h = sort { versioncmp($h{$a}, $h{$b}) } keys %h;

=head1 DESCRIPTION	

Sort::Versions allows easy sorting of mixed non-numeric and numeric strings,
like the 'version numbers' that many shared library systems and revision
control packages use. This is quite useful if you are trying to deal with
shared libraries. It can also be applied to applications that intersperse
variable-width numeric fields within text. Other applications can
undoubtedly be found.

For an explanation of the algorithm, it's simplest to look at these examples:

  1.1   <  1.2
  1.1a  <  1.2
  1.1   <  1.1.1
  1.1   <  1.1a
  1.1.a <  1.1a
  1     <  a
  a     <  b
  1     <  2
  1.1-3 <  1.1-4
  1.1-5 <  1.1.6

More precisely (but less comprehensibly), the two strings are treated
as subunits delimited by periods or hyphens. Each subunit can contain
any number of groups of digits or non-digits. If digit groups are
being compared on both sides, a numeric comparison is used, otherwise
a ASCII ordering is used. A group or subgroup with more units will win
if all comparisons are equal.  A period binds digit groups together
more tightly than a hyphen.

Some packages use a different style of version numbering: a simple
real number written as a decimal. Sort::Versions has limited support