source: trunk/essentials/dev-lang/perl/lib/Digest.pm

package Digest;

use strict;
use vars qw($VERSION %MMAP $AUTOLOAD);

$VERSION = "1.14";

%MMAP = (
  "SHA-1"      => ["Digest::SHA1", ["Digest::SHA", 1], ["Digest::SHA2", 1]],
  "SHA-224"    => [["Digest::SHA", 224]],
  "SHA-256"    => [["Digest::SHA", 256], ["Digest::SHA2", 256]],
  "SHA-384"    => [["Digest::SHA", 384], ["Digest::SHA2", 384]],
  "SHA-512"    => [["Digest::SHA", 512], ["Digest::SHA2", 512]],
  "HMAC-MD5"   => "Digest::HMAC_MD5",
  "HMAC-SHA-1" => "Digest::HMAC_SHA1",
  "CRC-16"     => [["Digest::CRC", type => "crc16"]],
  "CRC-32"     => [["Digest::CRC", type => "crc32"]],
  "CRC-CCITT"  => [["Digest::CRC", type => "crcccitt"]],
);

sub new
{
    shift;  # class ignored
    my $algorithm = shift;
    my $impl = $MMAP{$algorithm} || do {
        $algorithm =~ s/\W+//;
        "Digest::$algorithm";
    };
    $impl = [$impl] unless ref($impl);
    my $err;
    for  (@$impl) {
        my $class = $_;
        my @args;
        ($class, @args) = @$class if ref($class);
        no strict 'refs';
        unless (exists ${"$class\::"}{"VERSION"}) {
            eval "require $class";
            if ($@) {
                $err ||= $@;
                next;
            }
        }
        return $class->new(@args, @_);
    }
    die $err;
}

sub AUTOLOAD
{
    my $class = shift;
    my $algorithm = substr($AUTOLOAD, rindex($AUTOLOAD, '::')+2);
    $class->new($algorithm, @_);
}

1;