AI-Prolog

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

    } => $class;
    lock_keys %$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)).
            if(X,Y,Z) :- once(wprologtest(X,R)) , wprologcase(R,Y,Z).
            wprologtest(X,yes) :- call(X). wprologtest(X,no). 
            wprologcase(yes,X,Y) :- call(X). 
            wprologcase(no,X,Y) :- call(Y).
            not(X)  :- if(X,fail,true). 
            or(X,Y) :- call(X).
            or(X,Y) :- call(Y).
            true. 
            % the following are handled internally.  Don't use the
            % := operator.  Eventually, I'll make this a fatal error.
            % See AI::Prolog::Engine::Builtins to see the code for these
            !          :=  1.

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

            # XXX This could be very dangerous if we accidentally try
            # to assign a term to itself!  See ChoicePoint->next_clause
            $self->{_goal}->next_clause( $o->{clause} );
            return 1;
        }
    }
    return;
}

sub _print {    # convenient testing hook
    print @_;
}

sub _warn {     # convenient testing hook
    warn @_;
}

use constant RETURN => 2;

sub do_primitive {    # returns false if fails
    my ( $self, $term, $c ) = @_;
    my $primitive = AI::Prolog::Engine::Primitives->find( $c->ID )
        or die sprintf "Cannot find primitive for %s (ID: %d)\n",
        $term->to_string, $c->ID;

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

If false, all calls to C<result> will return Perl data structures instead of
nicely formatted output.

If called with no arguments, this method returns the current C<formatted>
value.

 Engine->formatted(1); # turn on formatting
 Engine->formatted(0); # turn off formatting (default)
 
 if (Engine->formatted) {
     # test if formatting is enabled
 }

B<Note>: if you choose to use the L<AI::Prolog|AI::Prolog> interface instead of
interacting directly with this class, that interface will set C<formatted> to
false.  You will have to set it back in your code if you do not wish this
behavior:

 use AI::Prolog;
 my $logic = AI::Prolog->new($prog_text);
 $logic->query($query_text);

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

=head2 C<raw_results([$boolean])>

The default value of C<raw_results> is false.  Setting this property to a true
value automatically sets C<formatted> to false.  C<results> will return the raw
data structures generated by questions when this property is true.
 
 Engine->raw_results(1); # turn on raw results
 Engine->raw_results(0); # turn off raw results (default)
 
 if (Engine->raw_results) {
     # test if raw results is enabled
 }

=head2 C<trace($boolean)>

Set this to a true value to turn on tracing.  This will trace through the
engine's goal satisfaction process while it's running.  This is very slow.

 Engine->trace(1); # turn on tracing
 Engine->trace(0); # turn off tracing

lib/AI/Prolog/Parser/PreProcessor/Math.pm  view on Meta::CPAN

    my ( $tokens, $index ) = @_;
    for my $i ( $index + 1 .. $#$tokens ) {
        return $i if defined $tokens->[$i];
    }
}

sub _as_string { ref $_[0] ? $_[0][1] : $_[0] }

sub match { shift; shift =~ $expression }

# The following are testing hooks

sub _compare            { shift; shift =~ /^$compare$/ }
sub _op                 { shift; shift =~ /^$op$/ }
sub _simple_rhs         { shift; shift =~ /^$simple_rhs$/ }
sub _simple_group_term  { shift; shift =~ /^$simple_group_term$/ }
sub _simple_math_term   { shift; shift =~ /^$simple_math_term$/ }
sub _math_term          { shift; shift =~ /^$math_term$/ }
sub _complex_rhs        { shift; shift =~ /^$complex_rhs$/ }
sub _complex_group_term { shift; shift =~ /^$complex_group_term$/ }

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

                . ").  Cannot bind to nonvar!" );
    }
}

# unbinds a term -- i.e., resets it to a variable
sub unbind {
    my $self = shift;
    $self->{bound} = 0;
    $self->{ref}   = undef;

    # XXX Now possible for a bind to have had no effect so ignore safety test
    # XXX if (bound) bound = false;
    # XXX else IO.error("Term.unbind","Can't unbind var!");
}

# set specific arguments.  A primitive way of constructing terms is to
# create them with Term(s,f) and then build up the arguments.  Using the
# parser is much simpler
sub setarg {
    my ( $self, $pos, $val ) = @_;
    if ( $self->{bound} && !$self->{deref} ) {