AI-Prolog

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

    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';

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

    $self->_splice_goal_list($term);
    CONTINUE;
};

my $HELP_OUTPUT;
$PRIMITIVES[31] = sub {    # help/0
    _load_builtins();
    if ( not $HELP_OUTPUT ) {
        $HELP_OUTPUT = "Help is available for the following builtins:\n\n";
        my @predicates = sort keys %DESCRIPTION_FOR;
        my $length     = length $LONGEST_PREDICATE;
        my $columns    = 5;
        my $format     = join '    ' => ("%-${length}s") x $columns;
        while (@predicates) {
            my @row;
            for ( 1 .. $columns ) {
                push @row => @predicates
                    ? shift @predicates
                    : '';
            }
            $HELP_OUTPUT .= sprintf $format => @row;
            $HELP_OUTPUT .= "\n";
        }

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

# peek at the next character
sub peek {
    my $self = shift;
    return '#' if $self->empty;
    return substr( $self->{_str} => ( $self->{_posn} + 1 ), 1 ) || '#';
}

# is the parsestring empty?
sub empty {
    my $self = shift;
    return $self->{_posn} >= length $self->{_str};
}

my $LINENUM = 1;

sub linenum {
    my $self = shift;
    if (@_) {
        $LINENUM = shift;
        return $self;
    }

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

sub advance_linenum {
    my $self = shift;
    $LINENUM++;
}

# Move a character forward
sub advance {
    my $self = shift;

    # print $self->current; # XXX
    $self->{_posn}++ unless $self->{_posn} >= length $self->{_str};
    $self->advance_linenum if $self->current =~ /[\r\n]/;
}

# all three get methods must be called before advance
# recognize a name (sequence of alphanumerics)
# XXX the java methods do not directly translate, so
#     we need to revisit this if it breaks
# XXX Update:  There was a subtle bug.  I think
#     I've nailed it, though.  The string index was off by one
sub getname {
    my $self = shift;

    $self->{_start} = $self->{_posn};
    my $getname;
    if ( $self->current =~ /['"]/ ) {

     # Normally, Prolog distinguishes between single and double quoted strings
        my $string = substr $self->{_str} => $self->{_start};
        $getname = extract_delimited($string);
        $self->{_posn} += length $getname;
        return substr $getname => 1, length($getname) - 2;  # strip the quotes
    }
    else {
        my $string = substr $self->{_str} => $self->{_start};
        ($getname) = $string =~ /^($ATOM)/;
        $self->{_posn} += length $getname;
        return $getname;
    }
}

# recognize a number
# XXX same issues as getname
sub getnum {
    my $self = shift;

    $self->{_start} = $self->{_posn};
    my $string = substr $self->{_str} => $self->{_start};
    my ($getnum) = $string =~ /^($RE{num}{real})/;
    if ( '.' eq substr $getnum => -1, 1 ) {
        $getnum = substr $getnum => 0, length($getnum) - 1;
    }
    $self->{_posn} += length $getnum;
    return $getnum;
}

# get the term corresponding to a name.
# if the name is new, create a new variable
sub getvar {
    my $self   = shift;
    my $string = $self->getname;
    my $term   = $self->{_vardict}{$string};
    unless ($term) {