#!perl -w
package version;

use 5.005_04;
use strict;

use vars qw(@ISA $VERSION $CLASS $STRICT $LAX *declare *qv);

$VERSION = 0.9902;

$CLASS = 'version';

#--------------------------------------------------------------------------#
# Version regexp components
#--------------------------------------------------------------------------#

# Fraction part of a decimal version number. This is a common part of
# both strict and lax decimal versions

my $FRACTION_PART = qr/\.[0-9]+/;

# First part of either decimal or dotted-decimal strict version number.
# Unsigned integer with no leading zeroes (except for zero itself) to
# avoid confusion with octal.

my $STRICT_INTEGER_PART = qr/0|[1-9][0-9]*/;

# First part of either decimal or dotted-decimal lax version number.
# Unsigned integer, but allowing leading zeros. Always interpreted
# as decimal. However, some forms of the resulting syntax give odd
# results if used as ordinary Perl expressions, due to how perl treats
# octals. E.g.
# version->new("010" ) == 10
# version->new( 010 ) == 8
# version->new( 010.2) == 82 # "8" . "2"

my $LAX_INTEGER_PART = qr/[0-9]+/;

# Second and subsequent part of a strict dotted-decimal version number.
# Leading zeroes are permitted, and the number is always decimal.
# Limited to three digits to avoid overflow when converting to decimal
# form and also avoid problematic style with excessive leading zeroes.

my $STRICT_DOTTED_DECIMAL_PART = qr/\.[0-9]{1,3}/;

# Second and subsequent part of a lax dotted-decimal version number.
# Leading zeroes are permitted, and the number is always decimal. No
# limit on the numerical value or number of digits, so there is the
# possibility of overflow when converting to decimal form.

my $LAX_DOTTED_DECIMAL_PART = qr/\.[0-9]+/;

# Alpha suffix part of lax version number syntax. Acts like a
# dotted-decimal part.

my $LAX_ALPHA_PART = qr/_[0-9]+/;

#--------------------------------------------------------------------------#
# Strict version regexp definitions
#--------------------------------------------------------------------------#

# Strict decimal version number.

my $STRICT_DECIMAL_VERSION =
qr/ $STRICT_INTEGER_PART $FRACTION_PART? /x;

# Strict dotted-decimal version number. Must have both leading "v" and
# at least three parts, to avoid confusion with decimal syntax.

my $STRICT_DOTTED_DECIMAL_VERSION =
qr/ v $STRICT_INTEGER_PART $STRICT_DOTTED_DECIMAL_PART{2,} /x;

# Complete strict version number syntax -- should generally be used
# anchored: qr/ \A $STRICT \z /x

$STRICT =
qr/ $STRICT_DECIMAL_VERSION | $STRICT_DOTTED_DECIMAL_VERSION /x;

#--------------------------------------------------------------------------#
# Lax version regexp definitions
#--------------------------------------------------------------------------#

# Lax decimal version number. Just like the strict one except for
# allowing an alpha suffix or allowing a leading or trailing
# decimal-point

my $LAX_DECIMAL_VERSION =
qr/ $LAX_INTEGER_PART (?: \. | $FRACTION_PART $LAX_ALPHA_PART? )?
|
$FRACTION_PART $LAX_ALPHA_PART?
/x;

# Lax dotted-decimal version number. Distinguished by having either
# leading "v" or at least three non-alpha parts. Alpha part is only
# permitted if there are at least two non-alpha parts. Strangely
# enough, without the leading "v", Perl takes .1.2 to mean v0.1.2,
# so when there is no "v", the leading part is optional

my $LAX_DOTTED_DECIMAL_VERSION =
qr/
v $LAX_INTEGER_PART (?: $LAX_DOTTED_DECIMAL_PART+ $LAX_ALPHA_PART? )?
|
$LAX_INTEGER_PART? $LAX_DOTTED_DECIMAL_PART{2,} $LAX_ALPHA_PART?
/x;

# Complete lax version number syntax -- should generally be used
# anchored: qr/ \A $LAX \z /x
#
# The string 'undef' is a special case to make for easier handling
# of return values from ExtUtils::MM->parse_version

$LAX =
qr/ undef | $LAX_DECIMAL_VERSION | $LAX_DOTTED_DECIMAL_VERSION /x;

#--------------------------------------------------------------------------#

# Preloaded methods go here.
sub import {
no strict 'refs';
my ($class) = shift;

# Set up any derived class
unless ($class eq 'version') {
local $^W;
*{$class.'::declare'} = \&version::declare;
*{$class.'::qv'} = \&version::qv;
}

my %args;
if (@_) { # any remaining terms are arguments
map { $args{$_} = 1 } @_
}
else { # no parameters at all on use line
%args =
(
qv => 1,
'UNIVERSAL::VERSION' => 1,
);
}

my $callpkg = caller();

if (exists($args{declare})) {
*{$callpkg.'::declare'} =
sub {return $class->declare(shift) }
unless defined(&{$callpkg.'::declare'});
}

if (exists($args{qv})) {
*{$callpkg.'::qv'} =
sub {return $class->qv(shift) }
unless defined(&{$callpkg.'::qv'});
}

if (exists($args{'VERSION'})) {
*{$callpkg.'::VERSION'} = \&version::_VERSION;
}

if (exists($args{'is_strict'})) {
*{$callpkg.'::is_strict'} = \&version::is_strict
unless defined(&{$callpkg.'::is_strict'});
}

if (exists($args{'is_lax'})) {
*{$callpkg.'::is_lax'} = \&version::is_lax
unless defined(&{$callpkg.'::is_lax'});
}
}

sub is_strict { defined $_[0] && $_[0] =~ qr/ \A $STRICT \z /x }
sub is_lax { defined $_[0] && $_[0] =~ qr/ \A $LAX \z /x }

1;