view release on metacpan or  search on metacpan

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

package AI::Prolog::KnowledgeBase;
$REVISION = '$Id: KnowledgeBase.pm,v 1.5 2005/06/25 23:06:53 ovid Exp $';
$VERSION  = '0.02';
use strict;
use warnings;
use Carp qw( confess carp );

use Hash::Util 'lock_keys';

use aliased 'AI::Prolog::Engine';
use aliased 'AI::Prolog::Parser';
use aliased 'AI::Prolog::TermList::Clause';

sub new {
    my $self = bless {
        ht         => {},
        primitives => {},    # only uses keys
        oldIndex   => "",
    } => shift;
    lock_keys %$self;
    return $self;
}

sub ht { shift->{ht} }       # temp hack XXX

sub to_string {
    my $self = shift;
    return "{"
        . (
        join ', ' => map { join '=' => $_->[0], $_->[1] }
            sort { $a->[2] <=> $b->[2] }
            map { [ $_, $self->_sortable_term( $self->{_vardict}{$_} ) ] }
            keys %{ $self->{ht} }
        ) . "}";
}

sub _sortable_term {
    my ( $self, $term ) = @_;
    my $string = $term->to_string;
    my $number = substr $string => 1;
    return $string, $number;
}

sub put {
    my ( $self, $key, $termlist ) = @_;
    $self->{ht}{$key} = $termlist;
}

sub elements { [ values %{ shift->{ht} } ] }

sub reset {
    my $self = shift;
    $self->{ht}         = {};
    $self->{primitives} = {};
    $self->{oldIndex}   = '';
}

sub consult {
    my ( $self, $program ) = @_;
    $self->{oldIndex} = '';
    return Parser->consult( $program, $self );
}

sub add_primitive {
    my ( $self, $clause ) = @_;
    my $term      = $clause->term;
    my $predicate = $term->predicate;
    my $c         = $self->{ht}{$predicate};
    if ($c) {
        while ( $c->next_clause ) {
            $c = $c->next_clause;
        }
        $c->next_clause($clause);
    }
    else {