path: root/inc/MBVersion.pm

# Bootstrap pure-perl version
package MB::Version;
use strict;

use vars qw($VERSION);
$VERSION = 0.86;

eval "use version $VERSION";
if ($@) { # can't locate new enough version files, use our own
    # We might be here because version.pm was present but there was
    # an error, so make we want to be sure users see what's happening
    # We also need to clear %INC entries, as the "undef" for a broken
    # version.pm can't be directly overwritten later.
    if ( exists $INC{'version.pm'} && ! defined $INC{'version.pm'} ) {
        warn "Error loading version.pm: $@\n";
        warn "Using Module::Build::Version bundled version code instead.\n";
        delete $INC{'version.pm'};
        delete $INC{'version/vpp.pm'};
    }

    # Avoid redefined warnings if an old version.pm was available
    delete $version::{$_} foreach keys %version::;

    # first we get the stub version module
    my $version;
    while (<DATA>) {
	s/(\$VERSION)\s=\s\d+/\$VERSION = 0/;
	$version .= $_ if $_;
	last if /^1;$/;
    }

    # and now get the current version::vpp code
    my $vpp;
    while (<DATA>) {
	s/(\$VERSION)\s=\s\d+/\$VERSION = 0/;
	$vpp .= $_ if $_;
	last if /^1;$/;
    }

    # but we eval them in reverse order since version depends on
    # version::vpp to already exist
    eval $vpp; die $@ if $@;
    $INC{'version/vpp.pm'} = 'inside Module::Build::Version';
    eval $version; die $@ if $@;
    $INC{'version.pm'} = 'inside Module::Build::Version';
}

1;
__DATA__
# XXX replace everything from here to the next XXX with the
# contents of version.pm from CPAN and then edit to ensure
# the XS clause is not invoked and comment out the line about
# C<< eval "use version::vpp $VERSION"; >> since we provide
# our own copy

package version;

use 5.005_04;
use strict;

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

$VERSION = 0.87;

$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;

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

#eval "use version::vxs $VERSION"; XXX DONT TRY XS
if ( 1 ) { # XXX FORCE PURE PERL
#    eval "use version::vpp $VERSION"; # don't tempt fate
#    die "$@" if ( $@ );
    push @ISA, "version::vpp";
    local $^W;
    *version::qv = \&version::vpp::qv;
    *version::declare = \&version::vpp::declare;
    *version::_VERSION = \&version::vpp::_VERSION;
    if ($] >= 5.009000 && $] < 5.011004) {
	no strict 'refs';
	*version::stringify = \&version::vpp::stringify;
	*{'version::(""'} = \&version::vpp::stringify;
	*version::new = \&version::vpp::new;
	*version::parse = \&version::vpp::parse;
    }
}
else { # use XS module
# XXX NO XS FOR US -- WE DELETED IT
}

# 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{'UNIVERSAL::VERSION'})) {
	local $^W;
	*UNIVERSAL::VERSION 
		= \&version::_VERSION;
    }

    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;

# XXX replace everything from here to the end with the current version/vpp.pm

package charstar;
# a little helper class to emulate C char* semantics in Perl
# so that prescan_version can use the same code as in C

use overload (
    '""'	=> \&thischar,
    '0+'	=> \&thischar,
    '++'	=> \&increment,
    '--'	=> \&decrement,
    '+'		=> \&plus,
    '-'		=> \&minus,
    '*'		=> \&multiply,
    'cmp'	=> \&cmp,
    '<=>'	=> \&spaceship,
    'bool'	=> \&thischar,
    '='		=> \&clone,
);

sub new {
    my ($self, $string) = @_;
    my $class = ref($self) || $self;

    my $obj = {
	string  => [split(//,$string)],
	current => 0,
    };
    return bless $obj, $class;
}

sub thischar {
    my ($self) = @_;
    my $last = $#{$self->{string}};
    my $curr = $self->{current};
    if ($curr >= 0 && $curr <= $last) {
	return $self->{string}->[$curr];
    }
    else {
	return '';
    }
}

sub increment {
    my ($self) = @_;
    $self->{current}++;
}

sub decrement {
    my ($self) = @_;
    $self->{current}--;
}

sub plus {
    my ($self, $offset) = @_;
    my $rself = $self->clone;
    $rself->{current} += $offset;
    return $rself;
}

sub minus {
    my ($self, $offset) = @_;
    my $rself = $self->clone;
    $rself->{current} -= $offset;
    return $rself;
}

sub multiply {
    my ($left, $right, $swapped) = @_;
    my $char = $left->thischar();
    return $char * $right;
}

sub spaceship {
    my ($left, $right, $swapped) = @_;
    unless (ref($right)) { # not an object already
	$right = $left->new($right);
    }
    return $left->{current} <=> $right->{current};
}

sub cmp {
    my ($left, $right, $swapped) = @_;
    unless (ref($right)) { # not an object already
	if (length($right) == 1) { # comparing single character only
	    return $left->thischar cmp $right;
	}
	$right = $left->new($right);
    }
    return $left->currstr cmp $right->currstr;
}

sub bool {
    my ($self) = @_;
    my $char = $self->thischar;
    return ($char ne '');
}

sub clone {
    my ($left, $right, $swapped) = @_;
    $right = {
	string  => [@{$left->{string}}],
	current => $left->{current},
    };
    return bless $right, ref($left);
}

sub currstr {
    my ($self, $s) = @_;
    my $curr = $self->{current};
    my $last = $#{$self->{string}};
    if (defined($s) && $s->{current} < $last) {
	$last = $s->{current};
    }

    my $string = join('', @{$self->{string}}[$curr..$last]);
    return $string;
}

package version::vpp;
use strict;

use POSIX qw/locale_h/;
use locale;
use vars qw ($VERSION @ISA @REGEXS);
$VERSION = 0.87;

use overload (
    '""'       => \&stringify,
    '0+'       => \&numify,
    'cmp'      => \&vcmp,
    '<=>'      => \&vcmp,
    'bool'     => \&vbool,
    'nomethod' => \&vnoop,
);

eval "use warnings";
if ($@) {
    eval '
	package warnings;
	sub enabled {return $^W;}
	1;
    ';
}

my $VERSION_MAX = 0x7FFFFFFF;

# implement prescan_version as closely to the C version as possible
use constant TRUE  => 1;
use constant FALSE => 0;

sub isDIGIT {
    my ($char) = shift->thischar();
    return ($char =~ /\d/);
}

sub isALPHA {
    my ($char) = shift->thischar();
    return ($char =~ /[a-zA-Z]/);
}

sub isSPACE {
    my ($char) = shift->thischar();
    return ($char =~ /\s/);
}

sub BADVERSION {
    my ($s, $errstr, $error) = @_;
    if ($errstr) {
	$$errstr = $error;
    }
    return $s;
}

sub prescan_version {
    my ($s, $strict, $errstr, $sqv, $ssaw_decimal, $swidth, $salpha) = @_;
    my $qv          = defined $sqv          ? $$sqv          : FALSE;
    my $saw_decimal = defined $ssaw_decimal ? $$ssaw_decimal : 0;
    my $width       = defined $swidth       ? $$swidth       : 3;
    my $alpha       = defined $salpha       ? $$salpha       : FALSE;

    my $d = $s;

    if ($qv && isDIGIT($d)) {
	goto dotted_decimal_version;
    }

    if ($d eq 'v') { # explicit v-string
	$d++;
	if (isDIGIT($d)) {
	    $qv = TRUE;
	}
	else { # degenerate v-string
	    # requires v1.2.3
	    return BADVERSION($s,$errstr,"Invalid version format (dotted-decimal versions require at least three parts)");
	}

dotted_decimal_version:
	if ($strict && $d eq '0' && isDIGIT($d+1)) {
	    # no leading zeros allowed
	    return BADVERSION($s,$errstr,"Invalid version format (no leading zeros)");
	}

	while (isDIGIT($d)) { 	# integer part
	    $d++;
	}

	if ($d eq '.')
	{
	    $saw_decimal++;
	    $d++; 		# decimal point
	}
	else
	{
	    if ($strict) {
		# require v1.2.3
		return BADVERSION($s,$errstr,"Invalid version format (dotted-decimal versions require at least three parts)");
	    }
	    else {
		goto version_prescan_finish;
	    }
	}

	{
	    my $i = 0;
	    my $j = 0;
	    while (isDIGIT($d)) {	# just keep reading
		$i++;
		while (isDIGIT($d)) {
		    $d++; $j++;
		    # maximum 3 digits between decimal
		    if ($strict && $j > 3) {
			return BADVERSION($s,$errstr,"Invalid version format (maximum 3 digits between decimals)");
		    }
		}
		if ($d eq '_') {
		    if ($strict) {
			return BADVERSION($s,$errstr,"Invalid version format (no underscores)");
		    }
		    if ( $alpha ) {
			return BADVERSION($s,$errstr,"Invalid version format (multiple underscores)");
		    }
		    $d++;
		    $alpha = TRUE;
		}
		elsif ($d eq '.') {
		    if ($alpha) {
			return BADVERSION($s,$errstr,"Invalid version format (underscores before decimal)");
		    }
		    $saw_decimal++;
		    $d++;
		}
		elsif (!isDIGIT($d)) {
		    last;
		}
		$j = 0;
	    }
	
	    if ($strict && $i < 2) {
		# requires v1.2.3
		return BADVERSION($s,$errstr,"Invalid version format (dotted-decimal versions require at least three parts)");
	    }
	}
    } 					# end if dotted-decimal
    else
    {					# decimal versions
	# special $strict case for leading '.' or '0'
	if ($strict) {
	    if ($d eq '.') {
		return BADVERSION($s,$errstr,"Invalid version format (0 before decimal required)");
	    }
	    if ($d eq '0' && isDIGIT($d+1)) {
		return BADVERSION($s,$errstr,"Invalid version format (no leading zeros)");
	    }
	}

	# consume all of the integer part
	while (isDIGIT($d)) {
	    $d++;
	}

	# look for a fractional part
	if ($d eq '.') {
	    # we found it, so consume it
	    $saw_decimal++;
	    $d++;
	}
	elsif (!$d || $d eq ';' || isSPACE($d) || $d eq '}') {
	    if ( $d == $s ) {
		# found nothing
		return BADVERSION($s,$errstr,"Invalid version format (version required)");
	    }
	    # found just an integer
	    goto version_prescan_finish;
	}
	elsif ( $d == $s ) {
	    # didn't find either integer or period
	    return BADVERSION($s,$errstr,"Invalid version format (non-numeric data)");
	}
	elsif ($d eq '_') {
	    # underscore can't come after integer part
	    if ($strict) {
		return BADVERSION($s,$errstr,"Invalid version format (no underscores)");
	    }
	    elsif (isDIGIT($d+1)) {
		return BADVERSION($s,$errstr,"Invalid version format (alpha without decimal)");
	    }
	    else {
		return BADVERSION($s,$errstr,"Invalid version format (misplaced underscore)");
	    }
	}
	elsif ($d) {
	    # anything else after integer part is just invalid data
	    return BADVERSION($s,$errstr,"Invalid version format (non-numeric data)");
	}

	# scan the fractional part after the decimal point
	if ($d && !isDIGIT($d) && ($strict || ! ($d eq ';' || isSPACE($d) || $d eq '}') )) {
		# $strict or lax-but-not-the-end
		return BADVERSION($s,$errstr,"Invalid version format (fractional part required)");
	}

	while (isDIGIT($d)) {
	    $d++;
	    if ($d eq '.' && isDIGIT($d-1)) {
		if ($alpha) {
		    return BADVERSION($s,$errstr,"Invalid version format (underscores before decimal)");
		}
		if ($strict) {
		    return BADVERSION($s,$errstr,"Invalid version format (dotted-decimal versions must begin with 'v')");
		}
		$d = $s; # start all over again
		$qv = TRUE;
		goto dotted_decimal_version;
	    }
	    if ($d eq '_') {
		if ($strict) {
		    return BADVERSION($s,$errstr,"Invalid version format (no underscores)");
		}
		if ( $alpha ) {
		    return BADVERSION($s,$errstr,"Invalid version format (multiple underscores)");
		}
		if ( ! isDIGIT($d+1) ) {
		    return BADVERSION($s,$errstr,"Invalid version format (misplaced underscore)");
		}
		$d++;
		$alpha = TRUE;
	    }
	}
    }

version_prescan_finish:
    while (isSPACE($d)) {
	$d++;
    }

    if ($d && !isDIGIT($d) && (! ($d eq ';' || $d eq '}') )) {
	# trailing non-numeric data
	return BADVERSION($s,$errstr,"Invalid version format (non-numeric data)");
    }

    if (defined $sqv) {
	$$sqv = $qv;
    }
    if (defined $swidth) {
	$$swidth = $width;
    }
    if (defined $ssaw_decimal) {
	$$ssaw_decimal = $saw_decimal;
    }
    if (defined $salpha) {
	$$salpha = $alpha;
    }
    return $d;
}

sub scan_version {
    my ($s, $rv, $qv) = @_;
    my $start;
    my $pos;
    my $last;
    my $errstr;
    my $saw_decimal = 0;
    my $width = 3;
    my $alpha = FALSE;
    my $vinf = FALSE;
    my @av;

    $s = new charstar $s;

    while (isSPACE($s)) { # leading whitespace is OK
	$s++;
    }

    $last = prescan_version($s, FALSE, \$errstr, \$qv, \$saw_decimal,
	\$width, \$alpha);

    if ($errstr) {
	# 'undef' is a special case and not an error
	if ( $s ne 'undef') {
	    use Carp;
	    Carp::croak($errstr);
	}
    }

    $start = $s;
    if ($s eq 'v') {
	$s++;
    }
    $pos = $s;

    if ( $qv ) {
	$$rv->{qv} = $qv;
    }
    if ( $alpha ) {
	$$rv->{alpha} = $alpha;
    }
    if ( !$qv && $width < 3 ) {
	$$rv->{width} = $width;
    }
    
    while (isDIGIT($pos)) {
	$pos++;
    }
    if (!isALPHA($pos)) {
	my $rev;

	for (;;) {
	    $rev = 0;
	    {
  		# this is atoi() that delimits on underscores
  		my $end = $pos;
  		my $mult = 1;
		my $orev;

		#  the following if() will only be true after the decimal
		#  point of a version originally created with a bare
		#  floating point number, i.e. not quoted in any way
		#
 		if ( !$qv && $s > $start && $saw_decimal == 1 ) {
		    $mult *= 100;
 		    while ( $s < $end ) {
			$orev = $rev;
 			$rev += $s * $mult;
 			$mult /= 10;
			if (   (abs($orev) > abs($rev)) 
			    || (abs($rev) > $VERSION_MAX )) {
			    warn("Integer overflow in version %d",
					   $VERSION_MAX);
			    $s = $end - 1;
			    $rev = $VERSION_MAX;
			    $vinf = 1;
			}
 			$s++;
			if ( $s eq '_' ) {
			    $s++;
			}
 		    }
  		}
 		else {
 		    while (--$end >= $s) {
			$orev = $rev;
 			$rev += $end * $mult;
 			$mult *= 10;
			if (   (abs($orev) > abs($rev)) 
			    || (abs($rev) > $VERSION_MAX )) {
			    warn("Integer overflow in version");
			    $end = $s - 1;
			    $rev = $VERSION_MAX;
			    $vinf = 1;
			}
 		    }
 		} 
  	    }

  	    # Append revision
	    push @av, $rev;
	    if ( $vinf ) {
		$s = $last;
		last;
	    }
	    elsif ( $pos eq '.' ) {
		$s = ++$pos;
	    }
	    elsif ( $pos eq '_' && isDIGIT($pos+1) ) {
		$s = ++$pos;
	    }
	    elsif ( $pos eq ',' && isDIGIT($pos+1) ) {
		$s = ++$pos;
	    }
	    elsif ( isDIGIT($pos) ) {
		$s = $pos;
	    }
	    else {
		$s = $pos;
		last;
	    }
	    if ( $qv ) {
		while ( isDIGIT($pos) ) {
		    $pos++;
		}
	    }
	    else {
		my $digits = 0;
		while ( ( isDIGIT($pos) || $pos eq '_' ) && $digits < 3 ) {
		    if ( $pos ne '_' ) {
			$digits++;
		    }
		    $pos++;
		}
	    }
	}
    }
    if ( $qv ) { # quoted versions always get at least three terms
	my $len = $#av;
	#  This for loop appears to trigger a compiler bug on OS X, as it
	#  loops infinitely. Yes, len is negative. No, it makes no sense.
	#  Compiler in question is:
	#  gcc version 3.3 20030304 (Apple Computer, Inc. build 1640)
	#  for ( len = 2 - len; len > 0; len-- )
	#  av_push(MUTABLE_AV(sv), newSViv(0));
	# 
	$len = 2 - $len;
	while ($len-- > 0) {
	    push @av, 0;
	}
    }

    # need to save off the current version string for later
    if ( $vinf ) {
	$$rv->{original} = "v.Inf";
	$$rv->{vinf} = 1;
    }
    elsif ( $s > $start ) {
	$$rv->{original} = $start->currstr($s);
	if ( $qv && $saw_decimal == 1 && $start ne 'v' ) {
	    # need to insert a v to be consistent
	    $$rv->{original} = 'v' . $$rv->{original};
	}
    }
    else {
	$$rv->{original} = '0';
	push(@av, 0);
    }

    # And finally, store the AV in the hash
    $$rv->{version} = \@av;

    # fix RT#19517 - special case 'undef' as string
    if ($s eq 'undef') {
	$s += 5;
    }

    return $s;
}

sub new
{
	my ($class, $value) = @_;
	my $self = bless ({}, ref ($class) || $class);
	my $qv = FALSE;
	
	if ( ref($value) && eval('$value->isa("version")') ) {
	    # Can copy the elements directly
	    $self->{version} = [ @{$value->{version} } ];
	    $self->{qv} = 1 if $value->{qv};
	    $self->{alpha} = 1 if $value->{alpha};
	    $self->{original} = ''.$value->{original};
	    return $self;
	}

	my $currlocale = setlocale(LC_ALL);

	# if the current locale uses commas for decimal points, we
	# just replace commas with decimal places, rather than changing
	# locales
	if ( localeconv()->{decimal_point} eq ',' ) {
	    $value =~ tr/,/./;
	}

	if ( not defined $value or $value =~ /^undef$/ ) {
	    # RT #19517 - special case for undef comparison
	    # or someone forgot to pass a value
	    push @{$self->{version}}, 0;
	    $self->{original} = "0";
	    return ($self);
	}

	if ( $#_ == 2 ) { # must be CVS-style
	    $value = $_[2];
	    $qv = TRUE;
	}

	$value = _un_vstring($value);

	# exponential notation
	if ( $value =~ /\d+.?\d*e[-+]?\d+/ ) {
	    $value = sprintf("%.9f",$value);
	    $value =~ s/(0+)$//; # trim trailing zeros
	}
	
	my $s = scan_version($value, \$self, $qv);

	if ($s) { # must be something left over
	    warn("Version string '%s' contains invalid data; "
                       ."ignoring: '%s'", $value, $s);
	}

	return ($self);
}

*parse = \&new;

sub numify 
{
    my ($self) = @_;
    unless (_verify($self)) {
	require Carp;
	Carp::croak("Invalid version object");
    }
    my $width = $self->{width} || 3;
    my $alpha = $self->{alpha} || "";
    my $len = $#{$self->{version}};
    my $digit = $self->{version}[0];
    my $string = sprintf("%d.", $digit );

    for ( my $i = 1 ; $i < $len ; $i++ ) {
	$digit = $self->{version}[$i];
	if ( $width < 3 ) {
	    my $denom = 10**(3-$width);
	    my $quot = int($digit/$denom);
	    my $rem = $digit - ($quot * $denom);
	    $string .= sprintf("%0".$width."d_%d", $quot, $rem);
	}
	else {
	    $string .= sprintf("%03d", $digit);
	}
    }

    if ( $len > 0 ) {
	$digit = $self->{version}[$len];
	if ( $alpha && $width == 3 ) {
	    $string .= "_";
	}
	$string .= sprintf("%0".$width."d", $digit);
    }
    else # $len = 0
    {
	$string .= sprintf("000");
    }

    return $string;
}

sub normal 
{
    my ($self) = @_;
    unless (_verify($self)) {
	require Carp;
	Carp::croak("Invalid version object");
    }
    my $alpha = $self->{alpha} || "";
    my $len = $#{$self->{version}};
    my $digit = $self->{version}[0];
    my $string = sprintf("v%d", $digit );

    for ( my $i = 1 ; $i < $len ; $i++ ) {
	$digit = $self->{version}[$i];
	$string .= sprintf(".%d", $digit);
    }

    if ( $len > 0 ) {
	$digit = $self->{version}[$len];
	if ( $alpha ) {
	    $string .= sprintf("_%0d", $digit);
	}
	else {
	    $string .= sprintf(".%0d", $digit);
	}
    }

    if ( $len <= 2 ) {
	for ( $len = 2 - $len; $len != 0; $len-- ) {
	    $string .= sprintf(".%0d", 0);
	}
    }

    return $string;
}

sub stringify
{
    my ($self) = @_;
    unless (_verify($self)) {
	require Carp;
	Carp::croak("Invalid version object");
    }
    return exists $self->{original} 
    	? $self->{original} 
	: exists $self->{qv} 
	    ? $self->normal
	    : $self->numify;
}

sub vcmp
{
    my ($left,$right,$swap) = @_;
    my $class = ref($left);
    unless ( eval { $right->isa($class) } ) {
	$right = $class->new($right);
    }

    if ( $swap ) {
	($left, $right) = ($right, $left);
    }
    unless (_verify($left)) {
	require Carp;
	Carp::croak("Invalid version object");
    }
    unless (_verify($right)) {
	require Carp;
	Carp::croak("Invalid version object");
    }
    my $l = $#{$left->{version}};
    my $r = $#{$right->{version}};
    my $m = $l < $r ? $l : $r;
    my $lalpha = $left->is_alpha;
    my $ralpha = $right->is_alpha;
    my $retval = 0;
    my $i = 0;
    while ( $i <= $m && $retval == 0 ) {
	$retval = $left->{version}[$i] <=> $right->{version}[$i];
	$i++;
    }

    # tiebreaker for alpha with identical terms
    if ( $retval == 0 
	&& $l == $r 
	&& $left->{version}[$m] == $right->{version}[$m]
	&& ( $lalpha || $ralpha ) ) {

	if ( $lalpha && !$ralpha ) {
	    $retval = -1;
	}
	elsif ( $ralpha && !$lalpha) {
	    $retval = +1;
	}
    }

    # possible match except for trailing 0's
    if ( $retval == 0 && $l != $r ) {
	if ( $l < $r ) {
	    while ( $i <= $r && $retval == 0 ) {
		if ( $right->{version}[$i] != 0 ) {
		    $retval = -1; # not a match after all
		}
		$i++;
	    }
	}
	else {
	    while ( $i <= $l && $retval == 0 ) {
		if ( $left->{version}[$i] != 0 ) {
		    $retval = +1; # not a match after all
		}
		$i++;
	    }
	}
    }

    return $retval;  
}

sub vbool {
    my ($self) = @_;
    return vcmp($self,$self->new("0"),1);
}

sub vnoop { 
    require Carp; 
    Carp::croak("operation not supported with version object");
}

sub is_alpha {
    my ($self) = @_;
    return (exists $self->{alpha});
}

sub qv {
    my $value = shift;
    my $class = 'version';
    if (@_) {
	$class = ref($value) || $value;
	$value = shift;
    }

    $value = _un_vstring($value);
    $value = 'v'.$value unless $value =~ /(^v|\d+\.\d+\.\d)/;
    my $version = $class->new($value);
    return $version;
}

*declare = \&qv;

sub is_qv {
    my ($self) = @_;
    return (exists $self->{qv});
}


sub _verify {
    my ($self) = @_;
    if ( ref($self)
	&& eval { exists $self->{version} }
	&& ref($self->{version}) eq 'ARRAY'
	) {
	return 1;
    }
    else {
	return 0;
    }
}

sub _is_non_alphanumeric {
    my $s = shift;
    $s = new charstar $s;
    while ($s) {
	return 0 if isSPACE($s); # early out
	return 1 unless (isALPHA($s) || isDIGIT($s) || $s =~ /[.-]/);
	$s++;
    }
    return 0;
}

sub _un_vstring {
    my $value = shift;
    # may be a v-string
    if ( length($value) >= 3 && $value !~ /[._]/ 
	&& _is_non_alphanumeric($value)) {
	my $tvalue;
	if ( $] ge 5.008_001 ) {
	    $tvalue = _find_magic_vstring($value);
	    $value = $tvalue if length $tvalue;
	}
	elsif ( $] ge 5.006_000 ) {
	    $tvalue = sprintf("v%vd",$value);
	    if ( $tvalue =~ /^v\d+(\.\d+){2,}$/ ) {
		# must be a v-string
		$value = $tvalue;
	    }
	}
    }
    return $value;
}

sub _find_magic_vstring {
    my $value = shift;
    my $tvalue = '';
    require B;
    my $sv = B::svref_2object(\$value);
    my $magic = ref($sv) eq 'B::PVMG' ? $sv->MAGIC : undef;
    while ( $magic ) {
	if ( $magic->TYPE eq 'V' ) {
	    $tvalue = $magic->PTR;
	    $tvalue =~ s/^v?(.+)$/v$1/;
	    last;
	}
	else {
	    $magic = $magic->MOREMAGIC;
	}
    }
    return $tvalue;
}

sub _VERSION {
    my ($obj, $req) = @_;
    my $class = ref($obj) || $obj;

    no strict 'refs';
    if ( exists $INC{"$class.pm"} and not %{"$class\::"} and $] >= 5.008) {
	 # file but no package
	require Carp;
	Carp::croak( "$class defines neither package nor VERSION"
	    ."--version check failed");
    }

    my $version = eval "\$$class\::VERSION";
    if ( defined $version ) {
	local $^W if $] <= 5.008;
	$version = version::vpp->new($version);
    }

    if ( defined $req ) {
	unless ( defined $version ) {
	    require Carp;
	    my $msg =  $] < 5.006 
	    ? "$class version $req required--this is only version "
	    : "$class does not define \$$class\::VERSION"
	      ."--version check failed";

	    if ( $ENV{VERSION_DEBUG} ) {
		Carp::confess($msg);
	    }
	    else {
		Carp::croak($msg);
	    }
	}

	$req = version::vpp->new($req);

	if ( $req > $version ) {
	    require Carp;
	    if ( $req->is_qv ) {
		Carp::croak( 
		    sprintf ("%s version %s required--".
			"this is only version %s", $class,
			$req->normal, $version->normal)
		);
	    }
	    else {
		Carp::croak( 
		    sprintf ("%s version %s required--".
			"this is only version %s", $class,
			$req->stringify, $version->stringify)
		);
	    }
	}
    }

    return defined $version ? $version->stringify : undef;
}

1; #this line is important and will help the module return a true value