package Data::RingBuffer;

sub new {
    my ($class, $size) = @_;
    return bless({
        head => 0,
        tail => 0,
        buf  => [ (undef) x $size ],
    }, $class);
}

sub is_empty {
    my ($self) = @_;
    return $self->{tail} == $self->{head};
}

sub dequeue {
    my ($self) = @_;
    my $buf = $self->{buf};
    return () if $self->is_empty();
    my $val = $buf->[$self->{tail}];
    $self->{tail} = ( $self->{tail} + 1 ) % @$buf;
    return $val;
}

sub is_full {
    my ($self) = @_;
    my $buf = $self->{buf};
    return ($self->{head} + 1) % @$buf == $self->{tail};
}

sub enqueue {
    my ($self, $val) = @_;
    my $buf = $self->{buf};
    return 0 if $self->is_full();
    $buf->[$self->{head}] = $val;
    $self->{head} = ( $self->{head} + 1 ) % @$buf;
    return 1;
}