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

## no critic (RcsKeywords,PodSections,InterpolationOfMetachars,EmptyQuotes,ConstantPragma,InitializationForLocalVars,LocalVars,PunctuationVars)
package AI::Prolog::Engine::Primitives;
$REVISION = '$Id: Primitives.pm,v 1.1 2005/08/06 23:28:40 ovid Exp $';
$VERSION  = '0.3';
use strict;
use warnings;

use base 'AI::Prolog::Engine';
use Scalar::Util 'looks_like_number';

use aliased 'AI::Prolog::Term';
use aliased 'AI::Prolog::Term::Cut';
use aliased 'AI::Prolog::Term::Number';
use aliased 'AI::Prolog::TermList';
use aliased 'AI::Prolog::TermList::Step';
use aliased 'AI::Prolog::ChoicePoint';

my %DESCRIPTION_FOR;
my $LONGEST_PREDICATE = '';

sub _load_builtins {
    return if keys %DESCRIPTION_FOR;
    require Pod::Simple::Text;
    require Pod::Perldoc;
    my $perldoc     = Pod::Perldoc->new;
    my $builtin_pod = 'AI::Prolog::Builtins';

    my ($found) = $perldoc->grand_search_init( [$builtin_pod] )
        or die "Help failed.  Cannot find documentation for $builtin_pod: $!";
    open my $fh, '<', $found
        or die "Cannot open $found for reading: ($!)";
    my @lines = <$fh>;
    close $fh or die "Cannot close $found: ($!)";

    while (@lines) {
        my $line = shift @lines;
        my $predicate;
        if ( $line =~ /\A=item\s*(\S+)/mx ) {
            $predicate = $1;
            if ( $predicate =~ m{.*/\d+}mx ) {
                my @pod = "=head1 $predicate";
                if ( length $predicate > length $LONGEST_PREDICATE ) {
                    $LONGEST_PREDICATE = $predicate;
                }
                while ( $line = shift @lines ) {
                    if ( $line =~ /\A=(?:item|back)/mx ) {
                        unshift @lines => $line;
                        last;
                    }
                    push @pod => $line;
                }
                push @pod => '=cut';

                # XXX I hate instantiating this here, but there
                # appears to be a bug in parsing if I don't :(
                my $parser = Pod::Simple::Text->new;
                my $output;
                $parser->output_string( \$output );
                $parser->parse_lines( @pod, undef );
                $DESCRIPTION_FOR{$predicate} = $output;
                $output = '';
            }
        }
    }

    return;
}

sub _remove_choices {

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

};

$PRIMITIVES[5] = sub {    # assert/1
    my ( $self, $term, $c ) = @_;
    $self->{_db}->assert( $term->getarg(0) );
    return CONTINUE;
};

$PRIMITIVES[7] = sub {    # retract/1
    my ( $self, $term, $c ) = @_;
    if ( not $self->{_db}->retract( $term->getarg(0), $self->{_stack} ) ) {
        $self->backtrack;
        return FAIL;
    }
    $self->{_cp}->clause( $self->{_retract_clause} )
        ;                 # if $self->{_cp}; # doesn't work
    return CONTINUE;
};

$PRIMITIVES[8] = sub {    # listing/0
    my $self = shift;
    $self->{_db}->dump(0);
    return CONTINUE;
};

$PRIMITIVES[9] = sub {    # listing/1
    my ( $self, $term, $c ) = @_;
    my $predicate = $term->getarg(0)->getfunctor;
    $self->{_db}->list($predicate);
    return CONTINUE;
};

$PRIMITIVES[10] = sub {    # print/1
    my ( $self, $term, $c ) = @_;
    AI::Prolog::Engine::_print( $term->getarg(0)->to_string );
    return CONTINUE;
};

$PRIMITIVES[11] = sub {    # println/1
    my ( $self, $term, $c ) = @_;
    AI::Prolog::Engine::_print( $term->getarg(0)->to_string . "\n" );
    return CONTINUE;
};

$PRIMITIVES[12] = sub { AI::Prolog::Engine::_print("\n"); CONTINUE };    # nl

$PRIMITIVES[13] = sub {    # trace. notrace.
    my ( $self, $term ) = @_;
    $self->{_trace} = $term->getfunctor eq 'trace';
    AI::Prolog::Engine::_print(
        'Trace ' . ( $self->{_trace} ? 'ON' : 'OFF' ) );
    return CONTINUE;
};

$PRIMITIVES[15] = sub {    # is/2
    my ( $self, $term, $c ) = @_;
    my $rhs = $term->getarg(0)->deref;
    my $lhs = $term->getarg(1)->value;
    if ( $rhs->is_bound ) {
        my $value = $rhs->value;
        if ( not looks_like_number($value) ) {
            return FAIL;
        }
        return $value == $lhs;
    }
    $rhs->bind( Number->new($lhs) );
    push @{ $self->{_stack} } => $rhs;
    return CONTINUE;
};

$PRIMITIVES[16] = sub {    # gt/2
    my ( $self, $term ) = @_;
    return ( $term->getarg(0)->value > $term->getarg(1)->value )
        ? CONTINUE
        : FAIL;
};

$PRIMITIVES[17] = sub {    # lt/2
    my ( $self, $term ) = @_;
    return ( $term->getarg(0)->value < $term->getarg(1)->value )
        ? CONTINUE
        : FAIL;
};

$PRIMITIVES[19] = sub {    # ge/2
    my ( $self, $term ) = @_;
    return ( $term->getarg(0)->value >= $term->getarg(1)->value )
        ? CONTINUE
        : FAIL;
};

$PRIMITIVES[20] = sub {    # le/2
    my ( $self, $term ) = @_;
    return ( $term->getarg(0)->value <= $term->getarg(1)->value )
        ? CONTINUE
        : FAIL;
};

$PRIMITIVES[22] = sub {    # halt/0
    my ( $self, $term ) = @_;
    $self->halt(1);
    CONTINUE;
};

$PRIMITIVES[23] = sub {    # var/1
    my ( $self, $term, $c ) = @_;
    return $term->getarg(0)->bound() ? FAIL : CONTINUE;
};

# plus(X,Y)  := 25.
# minux(X,Y) := 26.
# mult(X,Y)  := 27.
# div(X,Y)   := 28.
# mod(X,Y)   := 29.

$PRIMITIVES[30] = sub {    # seq/1
    my ( $self, $term, $c ) = @_;
    $self->_splice_goal_list($term);
    CONTINUE;
};