RDFStore::Resource - An RDF Resource Node implementation

RDFStore documentation Contained in the RDFStore distribution.

Index

Code Index:

NAME

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RDFStore::Resource - An RDF Resource Node implementation

SYNOPSIS

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	use RDFStore::Resource;
	my $resource = new RDFStore::Resource("http://pen.jrc.it/index.html");
	my $resource1 = new RDFStore::Resource("http://pen.jrc.it/","index.html");

	print $resource->toString." is ";
        print "not"
        	unless $resource->equals($resource1);
        print " equal to ".$resource1->toString."\n";

	# or from URI object	
	use URI;
	$resource = new RDFStore::Resource("http://www.w3.org/1999/02/22-rdf-syntax-ns#","Description");
	$resource1 = new RDFStore::Resource( new URI("http://www.w3.org/1999/02/22-rdf-syntax-ns#Description") );

	print $resource->toString." is ";
        print "not"
        	unless $resource->equals($resource1);
        print " equal to ".$resource1->toString."\n";

	my $resource = new RDFStore::Resource([ a,{ d => 'value'}, [ 1,2,3] ]);

        print $resource->toString." is ";
        print "not"
                unless($resource->isbNode);
        print " anonymous\n";

DESCRIPTION

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An RDF Resource Node implementation which support the so called anonymous-resources or bNodes (blankNodes)

METHODS

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new ( LOCALNAME_NAMESPACE [, LOCALNAME ] )

This is a class method, the constructor for RDFStore::Resource. In case the method is called with a single perl scalar as parameter a new RDF Resource is created with the string passed as indentifier (LOCALNAME); a fully qualified RDF resource can be constructed by invoching the constructor with two paramters where the former is the NAMESPACE and the latter is the LOCALNAME. By RDF definition we assume that LOCALNAME can not be undefined. If LOCALNAME is a perl reference the new Resource is flagged as anonymous-resource or bNode :)

bNodes can be created either passing a perl reference to the constructor or by using the RDFStore::NodeFactory(3) createbNode() or createAnonymousResource() methods; the latter is actually setting the RDFStore::Resource internal bNode flag.

isAnonymous

Return true if the RDF Resource is anonymous or is a bNode

isbNode

Return true if the RDF Resource is anonymous or is a bNode

getURI

Return the URI identifing the RDF Resource; an undefined values i returned if the node is blank or anonymous.

getNamespace

Return the Namespace identifier of the Resource

getLocalName

Return the LocalName identifier of the Resource; if the Resource is anonymous (bNode) the Storable(3) representation of the label is returned instead. This will allow to distinguish bNodes between normal resources and give them a kind of unique identity. NOTE See RDFStore::Model(3) to see how actually bNodes are being stored and retrieved in RDFStore(3).

getLabel

Return the URI identifing the RDF Resource.

equals

Compare two RDF Resources either textual

getNodeID

Return the rdf:nodeID if the Resource is anonymous (bNode).

getbNode

Return the bNode conent.

SEE ALSO

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RDFStore::RDFNode(3)

ABOUT RDF

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 http://www.w3.org/TR/rdf-primer/

 http://www.w3.org/TR/rdf-mt

 http://www.w3.org/TR/rdf-syntax-grammar/

 http://www.w3.org/TR/rdf-schema/

 http://www.w3.org/TR/1999/REC-rdf-syntax-19990222 (obsolete)

AUTHOR

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	Alberto Reggiori <areggiori@webweaving.org>
RDFStore documentation Contained in the RDFStore distribution. 
# *
# *     Copyright (c) 2000-2006 Alberto Reggiori <areggiori@webweaving.org>
# *                        Dirk-Willem van Gulik <dirkx@webweaving.org>
# *
# * NOTICE
# *
# * This product is distributed under a BSD/ASF like license as described in the 'LICENSE'
# * file you should have received together with this source code. If you did not get a
# * a copy of such a license agreement you can pick up one at:
# *
# *     http://rdfstore.sourceforge.net/LICENSE
# *
# * Changes:
# *     version 0.1 - 2000/11/03 at 04:30 CEST
# *     version 0.2
# *             - modified new() getURI() getLabel() and added getNamespace() 
# *		  getLocalName()methods accordingly to rdf-api-2000-10-30
# *             - modified toString()
# *     version 0.3
# *             - fixed bugs when checking references/pointers (defined and ref() )
# *     version 0.4
# *		- added check on local name when create a new Resource
# *		- updated accordingly to rdf-api-2001-01-19
# *		- allow creation of resources from URI(3) objects or strings using XMLNS LocalPart
# *		- hashCode() and getDigest() return separated values for localName and namespace if requested
# * 	version 0.41
# *		- added anonymous resources support - see also RDFStore::NodeFactory(3) and RDFStore::Model(3)
# *		- added isAnonymous() and isbNode()
# *             - updated accordingly to new RDFStore API
# *             - removed BLOB support
# *

package RDFStore::Resource;
{
use vars qw ($VERSION);
use strict;
 
$VERSION = '0.41';

use Carp;
use RDFStore; # load the underlying C code in RDFStore.xs because it is all in one module file
use RDFStore::RDFNode;

sub isbNode {
	return $_[0]->isAnonymous;
};

sub getURI {
	return
		if($_[0]->isAnonymous); #bNodes do not have a URI

	return $_[0]->getLabel;
};

sub getNodeID {
        return
                unless($_[0]->isAnonymous);

        return $_[0]->getLabel;
	};

sub equals {
	return 0
                unless(defined $_[1]);

	return 0
                if ( ref($_[1]) =~ /^(SCALAR|ARRAY|HASH|CODE|REF|GLOB|LVALUE)/ ); #see perldoc perlfunc ref()

	return 0
		unless(	(defined $_[1]) &&
			(ref($_[1])) &&
			($_[1]->isa("RDFStore::Resource")) );

	return ( $_[0]->isAnonymous && $_[1]->isAnonymous ) ? ( $_[0]->getNodeID eq $_[1]->getNodeID ) : $_[0]->SUPER::equals($_[1])
        	if(	($_[0]->isAnonymous) ||
			($_[1]->isAnonymous) );

	# resources are equal if $_[0]->getURI() eq $_[1]->getURI() unless anonymous; then the digest is checked instead - see RDFStore::RDFNode(3)
	unless( $_[0]->getNamespace() ) {
        	unless($_[1]->getNamespace()) {
			return ( $_[0]->getLocalName() eq $_[1]->getLocalName() ) ? 1 : 0;
		} else { # maybe $_[1] did not detect names
			return ($_[0]->getLocalName() eq $_[1]->getURI()) ? 1 : 0;
			};
	} else {
        	if($_[1]->getNamespace()) {
			return (	( $_[0]->getLocalName() eq $_[1]->getLocalName() ) &&
					( $_[0]->getNamespace() eq $_[1]->getNamespace()) ) ? 1 : 0;
		} else { # maybe $_[1] did not detect names
			return ($_[0]->getURI() eq $_[1]->getURI()) ? 1 : 0;
			};
		};
        return $_[0]->SUPER::equals($_[1]);
};

1;
};

__END__