package Cache::LRU {
    use Hash::Ordered;
    use Mew;

    has _cache   => InstanceOf['Hash::Ordered'], (default => sub { Hash::Ordered->new });
    has max_size => PositiveOrZeroInt,           (default => 20);

    sub set ($self, $key, $value) {
        if ( $self->_cache->exists($value) ) {
            $self->_cache->delete($value);
        }
        elsif ( $self->_cache->keys > $self->max_size ) {
            $self->_cache->shift;
        }
        $self->_cache->set( $key, $value );
    }

    sub get ($self, $key) {
        return unless $self->_cache->exists($key);
        return $self->_cache->set( $key, $self->_cache->delete($key) );
    }
}