package Fuzzy::Matcher::Xor2;
use strict;
use warnings;
use Fuzzy::Matcher;
use vars qw/$VERSION @ISA/;

@ISA=qw(Fuzzy::Matcher);
$VERSION=0.01;

# Original implementation by [BrowserUk]
# bugfixes and modified to fit Fuzzy::Matcher interface by [demerphq]
sub _init {
  my ($self)=@_;
  $self->{minZeros} = chr( 0 ) x int( $self->{strlen} / ( $self->{fuzz
+} + 1 ) );
  $self->{minZlen} = length $self->{minZeros};
}


sub fuzz_search {
  my ($self,$seq)=@_;
  use bytes;
  my $FUZZY    = $self->{fuzz};
  my $seqLen   = length $seq;
  my $keyLen   = $self->{strlen};
  my $minZeros = $self->{minZeros};
  my $minZlen  = $self->{minZlen};
  my ($masked,$pos);

  my @matches;

  for my $key ( @{$self->{str_array}} ) {
    
    my $mask     = $key x ( int( $seqLen / $keyLen ) + 1 );
    my $maskLen  = length $mask;
    
    for my $offset1 ( 0 .. $keyLen-1 ) {
        $masked =  $mask ^ substr( $seq, $offset1, $maskLen );

        $pos = 0;
        while(
            $pos = 1+index  $masked, $minZeros, $pos
        ) {
            $pos--;
            my $offset2 = $pos - ($pos % $keyLen );
            last if $offset1+$offset2+$keyLen>$seqLen;
            
            my $fuz = $keyLen -
              ( substr( $masked, $offset2, $keyLen ) =~ tr[\0][\0] );
            if( $fuz <= $FUZZY ) {
                push @matches,$offset1 + $offset2,$fuz,$key;
            }
            $pos = $offset2 + $keyLen;
        }

    }
  }
  return \@matches;
}

1;
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