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package Algorithm::Nhash;
BEGIN {
  $Algorithm::Nhash::DIST = 'Algorithm-Nhash';
}
BEGIN {
  $Algorithm::Nhash::VERSION = '0.002';
}
# ABSTRACT: Exim nhash algorithm
use warnings;
use strict;

use Carp;

use vars qw( @ISA @EXPORT_OK );
@ISA = qw( Exporter );
@EXPORT_OK = qw( nhash );


sub new {
    my($class, @div) = @_;
    return bless \@div, $class;
}


my @primes = qw( 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79
                 83 89 97 101 103 107 109 113);

sub nhash {
    my($string, @div) = @_;
    if (ref $string) {          # called as a method
        # $string is actually $self
        ($string, @div) = ($div[0], @$string);
    }

    #warn "'$string' @div";

    my($sum, $i);
    foreach my $val (split //, $string) {
        $i += 28; $i %= 29;
        $sum += $primes[$i] * ord($val);
    }

    return $sum unless @div;
    my @ret;
    while (my $div = pop @div) {
        unshift @ret, $sum % $div;
        $sum = int($sum / $div);
    }

    return wantarray ? @ret : join '/', @ret;
}


1;

__END__
=pod

=head1 NAME

Algorithm::Nhash - Exim nhash algorithm

=head1 VERSION

version 0.002

=head1 SYNOPSIS

Procedural usage:

 use Algorithm::Nhash qw( nhash );
 # prints 228769
 print nhash('supercalifragilisticexpialidocious');
 # prints 417 (which is 228769 % 512)
 print nhash('supercalifragilisticexpialidocious', 512);
 # prints '6/33' (6*64 + 3 == 417)
 print nhash('supercalifragilisticexpialidocious', 8, 64);
 # assigns (6, 33) to @nhash
 my @nhash = nhash('supercalifragilisticexpialidocious', 8, 64);

OO usage: