use Types::Standard qw(Maybe);
use DX::Step::Backtrack;
use DX::Step::InvokeNextPredicate;
+use DX::Step::MarkAsSolution;
use DX::Class;
has current_hypothesis => (is => 'ro', isa => Hypothesis, required => 1);
-has next_step => (is => 'ro', isa => Maybe[Step]);
+has next_step => (is => 'ro', isa => Maybe[Step], required => 1);
has propositions => (is => 'ro', isa => PropositionSequence, required => 1);
has is_solution_state => (is => 'ro', required => 1);
+has on_exhaustion_step => (is => 'ro', isa => Maybe[Step], required => 1);
+
+has on_solution_step => (is => 'ro', isa => Maybe[Step], required => 1);
+
sub next_proposition {
my ($self, $hyp) = @_;
$hyp ||= $self->current_hypothesis;
$class->new(
current_hypothesis => $hyp,
alternatives => [],
- next_step => DX::Step::InvokeNextPredicate->new(
- proposition => $props->members->[0],
- ),
propositions => $props,
- is_solution_state => 0,
+ (@{$props->members}
+ ? (
+ next_step => DX::Step::InvokeNextPredicate->new(
+ proposition => $props->members->[0],
+ ),
+ is_solution_state => 0,
+ )
+ : ( next_step => undef, is_solution_state => 1 )
+ ),
+ on_exhaustion_step => undef,
+ on_solution_step => DX::Step::MarkAsSolution->new,
);
}