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lib/AI/Prolog/Engine.pm  view on Meta::CPAN

        _stack          => [],
        _db             => KnowledgeBase->new,
        _goal           => TermList->new( $term, undef ),    # TermList
        _call           => $term,                            # Term
        _run_called     => undef,
        _cp             => undef,
        _retract_clause => undef,
        _trace       => 0,       # whether or not tracing is done
        _halt        => 0,       # will stop the aiprolog shell
        _perlpackage => undef,
        _step_flag   => undef,
    } => $class;
    lock_keys %$self;

    # to add a new primitive, use the binding operator (:=) to assign a unique
    # index to the primitive and add the corresponding definition to
    # @PRIMITIVES.
    eval {
        $self->_adding_builtins(1);
        $self->{_db} = Parser->consult( <<'        END_PROG', $prog );
            ne(X, Y) :- not(eq(X,Y)).

lib/AI/Prolog/Engine.pm  view on Meta::CPAN

    my $stackTop = 0;

    while (1) {
        $stackTop = @{ $self->{_stack} };

        if ( $self->{_goal} && $self->{_goal}->isa(Step) ) {
            $self->{_goal} = $self->{_goal}->next;
            if ( $self->{_goal} ) {
                $self->{_goal}->resolve( $self->{_db} );
            }
            $self->{_step_flag} = 1;
            $self->trace(1);
        }
        $self->dump_goal if $self->{_trace};
        $self->step      if $self->{_step_flag};

        unless ( $self->{_goal} ) {

            # we've succeeded.  return results
            if ( $self->formatted ) {
                return $self->_call->to_string;
            }
            else {
                my @results = $self->_call->to_data;
                return $self->raw_results