package Digest::base;

use strict;

use vars qw($VERSION);

$VERSION = "1.16";

# subclass is supposed to implement at least these

sub new;

sub clone;

sub add;

sub digest;

sub reset {

    my $self = shift;

    $self->new(@_);  # ugly

}

sub addfile {

    my ($self, $handle) = @_;

    my $n;

    my $buf = "";

    while (($n = read($handle, $buf, 4*1024))) {

        $self->add($buf);

    }

    unless (defined $n) {

	require Carp;

	Carp::croak("Read failed: $!");

    }

    $self;

}

sub add_bits {

    my $self = shift;

    my $bits;

    my $nbits;

    if (@_ == 1) {

	my $arg = shift;

	$bits = pack("B*", $arg);

	$nbits = length($arg);

    }

    else {

	($bits, $nbits) = @_;

    }

    if (($nbits % 8) != 0) {

	require Carp;

	Carp::croak("Number of bits must be multiple of 8 for this algorithm");

    }

    return $self->add(substr($bits, 0, $nbits/8));

}

sub hexdigest {

    my $self = shift;

    return unpack("H*", $self->digest(@_));

}

sub b64digest {

    my $self = shift;

    require MIME::Base64;

    my $b64 = MIME::Base64::encode($self->digest(@_), "");

    $b64 =~ s/=+$//;

    return $b64;

}

1;

__END__

=head1 NAME

Digest::base - Digest base class

=head1 SYNOPSIS

  package Digest::Foo;

  use base 'Digest::base';

=head1 DESCRIPTION

The C<Digest::base> class provide implementations of the methods

C<addfile> and C<add_bits> in terms of C<add>, and of the methods

C<hexdigest> and C<b64digest> in terms of C<digest>.

Digest implementations might want to inherit from this class to get

this implementations of the alternative I<add> and I<digest> methods.

A minimal subclass needs to implement the following methods by itself:

    new

    clone

    add

    digest

The arguments and expected behaviour of these methods are described in

L<Digest>.

=head1 SEE ALSO

L<Digest>