SPARQLQueryImpl.java

/*
   This file is part of the LarKC platform 
   http://www.larkc.eu/

   Copyright 2010 LarKC project consortium

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
 */
package eu.larkc.core.query;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Set;

import org.openrdf.model.BNode;
import org.openrdf.model.Statement;
import org.openrdf.model.URI;
import org.openrdf.model.ValueFactory;
import org.openrdf.model.impl.ContextStatementImpl;
import org.openrdf.model.impl.LiteralImpl;
import org.openrdf.model.impl.StatementImpl;
import org.openrdf.model.impl.URIImpl;
import org.openrdf.model.impl.ValueFactoryImpl;
import org.openrdf.model.vocabulary.RDF;
import org.openrdf.query.MalformedQueryException;
import org.openrdf.query.impl.DatasetImpl;
import org.openrdf.query.parser.ParsedBooleanQuery;
import org.openrdf.query.parser.ParsedGraphQuery;
import org.openrdf.query.parser.ParsedQuery;
import org.openrdf.query.parser.ParsedTupleQuery;
import org.openrdf.query.parser.sparql.SPARQLParser;

import eu.larkc.core.data.CloseableIterator;
import eu.larkc.core.data.DataFactory;
import eu.larkc.core.data.DataSet;
import eu.larkc.core.data.DataSetImpl;
import eu.larkc.core.data.RdfGraph;
import eu.larkc.core.data.SPARQLEndpoint;
import eu.larkc.core.data.SetOfStatements;
import eu.larkc.core.data.SetOfStatementsImpl;
import eu.larkc.core.util.RDFConstants;

/**
 * SPARQLQueryImpl is the default SPARQLQuery implementation.
 * 
 * @author vassil
 * 
 */
public class SPARQLQueryImpl implements SPARQLQuery {

	private ParsedQuery query;
	private static SPARQLParser parser = new SPARQLParser();
	private String originalQuery;
	private String originalNS;
	private URI label;
	private static final long serialVersionUID = 1L;

	/**
	 * Constructor of the class.
	 * 
	 * @param query
	 *            SPARQL query
	 * @param ns
	 *            default namespace to be applied
	 */
	public SPARQLQueryImpl(String query, String ns) {
		if (query == null || ns == null) {
			throw new IllegalArgumentException("null!");
		}
		try {
			this.query = parser.parseQuery(query, ns);
			this.originalQuery = query;
			this.originalNS = ns;
		} catch (MalformedQueryException mqe) {
			throw new IllegalArgumentException("Not a valid SPARQL query!", mqe);
		}
	}

	/**
	 * Constructor of the class.
	 * 
	 * @param query
	 *            SPARQL query
	 */
	public SPARQLQueryImpl(String query) {
		this(query, RDF.TYPE.stringValue());
	}

	public boolean isAsk() {
		return query instanceof ParsedBooleanQuery;
	}

	public boolean isDescribe() {
		if (getGraphQuery() < 0) {
			return true;
		}
		return false;
	}

	public boolean isConstruct() {
		if (getGraphQuery() > 0) {
			return true;
		}
		return false;
	}

	public boolean isSelect() {
		return query instanceof ParsedTupleQuery;
	}

	public DataSet getDataSet() {
		SPARQLEndpoint local = DataFactory.INSTANCE.createRdfStoreConnection();
		return new DataSetImpl(local, query.getDataset().getDefaultGraphs(),
				query.getDataset().getNamedGraphs());
	}

	public void setDataSet(DataSet ds) {
		if (LocalStoreSPARQLService.class.isInstance(ds.getSPARQLEndpoint()) == false) {
			throw new IllegalArgumentException(
					"Remote dataset could not be assigned"
							+ " to local queries!");
		}
		DatasetImpl d = new DatasetImpl();
		if (ds != null) {
			for (RdfGraph g : ds.getDefaultGraphs()) {
				d.addDefaultGraph(g.getName());
			}
			for (RdfGraph g : ds.getNamedGraphs()) {
				d.addNamedGraph(g.getName());
			}
		}
		query.setDataset(d);
	}

	public SetOfStatements toRDF() {
		Set<Statement> statements = new HashSet<Statement>();

		ValueFactory rdfval = new ValueFactoryImpl();

		BNode bnode = rdfval.createBNode();

		statements.add(new StatementImpl(bnode, RDFConstants.RDF_TYPE,
				RDFConstants.LARKC_SPARQLQUERY));
		statements.add(new StatementImpl(bnode,
				RDFConstants.LARKC_HASSERIALIZEDFORM, new LiteralImpl(
						this.originalQuery)));

		return new SetOfStatementsImpl(statements);
	}

	public URI getLabelledGroup() {
		return label;
	}

	public void setLabelledGroup(URI label) {
		this.label = label;
	}

	public ParsedQuery getParsedQuery() {
		return query;
	}

	public String toString() {
		return originalQuery;
	}

	/**
	 * Check the query type.
	 * 
	 * @return 1 >= construct, 0 = other, -1 <= describe
	 */
	private int getGraphQuery() {
		if (query instanceof ParsedGraphQuery == false) {
			return 0;
		}
		int c = originalQuery.toUpperCase().indexOf("CONSTRUCT");
		if (c == -1) {
			return -1;
		}
		int d = originalQuery.toUpperCase().indexOf("DESCRIBE");
		if (d == -1) {
			return 1;
		}
		return d - c;
	}

	// Custom serialization
	private void writeObject(ObjectOutputStream out) throws IOException {
		out.writeObject(originalQuery);
		out.writeObject(originalNS);
	}

	@SuppressWarnings("unchecked")
	private void readObject(ObjectInputStream in) throws IOException,
			ClassNotFoundException {
		originalQuery = (String) in.readObject();
		originalNS = (String) in.readObject();
		try {
			this.query = parser.parseQuery(originalQuery, originalNS);
		} catch (MalformedQueryException mqe) {
			throw new RuntimeException("Invalid internal validation!");
		}
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see eu.larkc.core.query.Query#toRDF(eu.larkc.core.data.SetOfStatements)
	 */
	@Override
	public SetOfStatements toRDF(SetOfStatements data) {
		ArrayList<Statement> list = new ArrayList<Statement>();
		list.add(new StatementImpl(
				ValueFactoryImpl.getInstance().createBNode(), new URIImpl(
						DataFactory.LARKC_NS + "sparql"), new LiteralImpl(
						originalQuery)));

		CloseableIterator<Statement> iter = data.getStatements();
		while (iter.hasNext()) {
			Statement s = iter.next();
			URI uri = (URI) s.getContext();
			if (s.getContext() == null) {
				uri = new URIImpl("http://larkc.eu/invocation/last_1");
			} else {
				uri = new URIImpl(s.getContext().stringValue() + "1");
			}
			list.add(new ContextStatementImpl(s.getSubject(), s.getPredicate(),
					s.getObject(), uri));
		}
		return new SetOfStatementsImpl(list);

	}
}