org.ontoware.rdf2go.model.node.impl.AbstractBlankNodeImpl Maven / Gradle / Ivy

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RDF2go is an implementation-independent Java API with the design goals: portability (hence the name), performance and ease of implementation. This project was started at FZI Forschungszentrum Informatik Karlsruhe, Germany - www.fzi.de

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/**
 * LICENSE INFORMATION
 * 
 * Copyright 2005-2008 by FZI (http://www.fzi.de). Licensed under a BSD license
 * (http://www.opensource.org/licenses/bsd-license.php)  = Max Völkel
 *  = FZI Forschungszentrum Informatik Karlsruhe, Karlsruhe,
 * Germany  = 2010
 * 
 * Further project information at http://semanticweb.org/wiki/RDF2Go
 */

package org.ontoware.rdf2go.model.node.impl;

import org.ontoware.rdf2go.model.node.BlankNode;
import org.ontoware.rdf2go.model.node.Node;
import org.ontoware.rdf2go.model.node.URI;


public abstract class AbstractBlankNodeImpl extends ResourceImpl implements BlankNode {
	
	private static final long serialVersionUID = -8075799672273675916L;
	
	private Object underlyingBlankNode;
	
	/** This method should only be called by RDF2Go implmentations */
	public AbstractBlankNodeImpl(Object underlyingBlankNode) {
		this.underlyingBlankNode = underlyingBlankNode;
	}
	
	/** This method should only be called by RDF2Go implmentations */
	public Object getUnderlyingBlankNode() {
		return this.underlyingBlankNode;
	}
	
	@Override
	public boolean equals(Object other) {
		return other instanceof AbstractBlankNodeImpl
		        && this.getUnderlyingBlankNode().equals(
		                ((AbstractBlankNodeImpl)other).getUnderlyingBlankNode());
	}
	
	@Override
	public String toString() {
		return this.underlyingBlankNode.toString();
	}
	
	@Override
    public URI asURI() throws ClassCastException {
		throw new ClassCastException("Cannot cast a BlankNode to a URI");
		
	}
	
	@Override
    public BlankNode asBlankNode() throws ClassCastException {
		return this;
	}
	
	@Override
	public int hashCode() {
		return this.underlyingBlankNode.hashCode();
	}
	
	@Override
    public int compareTo(Node other) {
		if(other instanceof BlankNode) {
			if(this.equals(other))
				return 0;
			// else somehow define a sorting order on blank nodes
			return this.hashCode() - other.hashCode();
			
		}
		// else sort by type
		return NodeUtils.compareByType(this, other);
	}
	
	@Override
    public String toSPARQL() throws UnsupportedOperationException {
		throw new UnsupportedOperationException(
		        "Variable (Singleton) cannot be used for SPARQL queries");
	}
	
	@Override
    public abstract String getInternalID();
}