package RememberingSet;

use Moo;
use Set;

my $Delegated = [qw/add has/];

has '_count' => (is => 'ro', default => sub { {  } });
has '_set'   => (is => 'ro', default => sub { Set->new }, handles => $Delegated);

around $Delegated => sub {
    my ($orig, $self, $e) = @_;

    $self->_count->{ $e }++;
    $self->$orig($e);
};

no Moo;

sub seen {
    my ($self, $e) = @_;

    exists $self->_count->{ $e }
      ? $self->_count->{ $e }
      : 0;
}

1;