File Coverage

blib/lib/Set/Similarity/BV.pm

Criterion	Covered	Total	%
statement	36	36	100.0
branch	10	10	100.0
condition	8	9	100.0
subroutine	13	13	100.0
pod	7	7	100.0
total	74	75	100.0

package Set::Similarity::BV;

use strict;
use warnings;

our $VERSION = '0.04';

use Carp 'croak';

sub new {
  my $class = shift;

  # uncoverable condition false
  bless @_ ? @_ > 1 ? {@_} : {%{$_[0]}} : {}, ref $class || $class;
}

sub similarity {
  my ($self, $hex1, $hex2) = @_;

  return 1 if (!($hex1 || $hex2));    # both zero
  return 0 unless ($hex1 && $hex2);   # one is zero

  #return 1 if (!(hex($hex1) || hex($hex2)));    # both zero
  #return 0 unless (hex($hex1) && hex($hex2) ); # one is zero

  no warnings 'portable'; # for 0xffffffffffffffff

  return $self->from_integers(
    hex($hex1),
    hex($hex2),
  );
}


sub from_integers { croak 'Method "from_integers" not implemented in subclass' }

sub intersection {
  my ($self,$v1,$v2) = @_;

  return $self->bits($v1 & $v2);
}

sub bits {
  my $v = $_[1];

  use integer;
  no warnings 'portable'; # for 0xffffffffffffffff

  $v = $v - (($v >> 1) & 0x5555555555555555);
  $v = ($v & 0x3333333333333333) + (($v >> 2) & 0x3333333333333333);
  # (bytesof($v) -1) * bitsofbyte = (8-1)*8 = 56 ----------------------vv
  $v = (($v + ($v >> 4) & 0x0f0f0f0f0f0f0f0f) * 0x0101010101010101) >> 56;

  return $v;
}

sub combined_length {
  my ($self,$v1,$v2) = @_;

  return $self->bits($v1) + $self->bits($v2);
}

sub min {
  ($_[1] < $_[2])
    ? $_[1] : $_[2];
}

1;

__END__