RDF::Query::Expression::Unary - Class for unary expressions

RDF-Query documentation Contained in the RDF-Query distribution.

Index

Code Index:

NAME

Top

RDF::Query::Expression::Unary - Class for unary expressions

VERSION

Top

This document describes RDF::Query::Expression::Unary version 2.907.

METHODS

Top

Beyond the methods documented below, this class inherits methods from the RDF::Query::Expression class.

sse

Returns the SSE string for this algebra expression.

as_sparql

Returns the SPARQL string for this algebra expression.

evaluate ( $query, \%bound )

Evaluates the expression using the supplied bound variables. Will return a RDF::Query::Node object.

AUTHOR

Top

 Gregory Todd Williams <gwilliams@cpan.org>
RDF-Query documentation Contained in the RDF-Query distribution. 
# RDF::Query::Expression::Unary
# -----------------------------------------------------------------------------


package RDF::Query::Expression::Unary;

use strict;
use warnings;
no warnings 'redefine';
use base qw(RDF::Query::Expression);

use Data::Dumper;
use Scalar::Util qw(blessed);
use Carp qw(carp croak confess);

######################################################################

our ($VERSION);
BEGIN {
	$VERSION	= '2.907';
}

######################################################################


sub sse {
	my $self	= shift;
	my $context	= shift;
	
	return sprintf(
		'(%s %s)',
		$self->op,
		map { $_->sse( $context ) } $self->operands,
	);
}


sub as_sparql {
	my $self	= shift;
	my $context	= shift;
	my $indent	= shift;
	my $op		= $self->op;
	return sprintf("($op %s)", map { $_->as_sparql( $context, $indent ) } $self->operands);
}


sub evaluate {
	my $self	= shift;
	my $query	= shift;
	my $bound	= shift;
	my $context	= shift;
	my $op		= $self->op;
	my ($data)	= $self->operands;
	if ($op eq '+' or $op eq '-') {
		my $l		= $data->isa('RDF::Query::Algebra')
					? $data->evaluate( $query, $bound, $context, @_ )
					: ($data->isa('RDF::Query::Node::Variable'))
						? $bound->{ $data->name }
						: $data;
		
		my $value;
		if ($op eq '+') {
			$value	= $l->numeric_value;
		} elsif ($op eq '-') {
			$value	= -1 * $l->numeric_value;
		}
		return RDF::Query::Node::Literal->new( $value, undef, $l->literal_datatype );
	} elsif ($op eq '!') {
		my $alg		= RDF::Query::Expression::Function->new( "sparql:ebv", $data );
		my $bool	= $alg->evaluate( $query, $bound, $context, @_ );
		if ($bool->literal_value eq 'true') {
			return RDF::Query::Node::Literal->new( 'false', undef, 'http://www.w3.org/2001/XMLSchema#boolean' );
		} else {
			return RDF::Query::Node::Literal->new( 'true', undef, 'http://www.w3.org/2001/XMLSchema#boolean' );
		}
	} else {
		warn "unknown unary op: $op";
		throw RDF::Query::Error::ExecutionError -text => "Unknown unary op '$op'";
	}
}


1;

__END__