org.deri.xquery.saxon.sparqlScopedDatasetExtFunction Maven / Gradle / Ivy

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/**
 *
 * Copyright (C) 2011, NUI Galway.
 * All rights reserved.
 *
 * The software in this package is published under the terms of the BSD style license a copy of which has been included
 * with this distribution in the bsb_license.txt file and/or available on NUI Galway Server at
 * http://xsparql.deri.ie/license/bsd_license.txt
 *
 * Created: 09 February 2011, Reasoning and Querying Unit (URQ), Digital Enterprise Research Institute (DERI) on behalf of
 * NUI Galway.
 */
package org.deri.xquery.saxon;

//import net.sf.saxon.functions.*;
import net.sf.saxon.lib.*;

import com.hp.hpl.jena.query.*;
import java.io.*;

import javax.xml.transform.stream.StreamSource;

import net.sf.saxon.tree.iter.*;
import net.sf.saxon.om.*;
import net.sf.saxon.value.SequenceType;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.trans.XPathException;

//import net.sf.saxon.value.StringValue;

/**
 * 
 * @author Nuno Lopes
 * @version 1.0
 */
public class sparqlScopedDatasetExtFunction extends ExtensionFunctionDefinition {

  /**
	 * 
	 */
  private static final long serialVersionUID = -2273348803776203631L;
  /**
   * Name of the function
   * 
   */
  private static StructuredQName funcname = new StructuredQName("_xsparql",
      "http://xsparql.deri.org/demo/xquery/xsparql.xquery",
      "sparqlScopedDataset");

  // new StructuredQName("_java", "java:org.deri.sparql.Sparql",
  // "sparqlScopedDataset");

  public sparqlScopedDatasetExtFunction() {
  }

  @Override
  public StructuredQName getFunctionQName() {
    return funcname;
  }

  @Override
  public int getMinimumNumberOfArguments() {
    return 4;
  }

  @Override
  public int getMaximumNumberOfArguments() {
    return 4;
  }

  @Override
  public SequenceType[] getArgumentTypes() {
    return new SequenceType[] { SequenceType.SINGLE_STRING,
        SequenceType.SINGLE_STRING, SequenceType.SINGLE_STRING,
        SequenceType.SINGLE_INTEGER };
  }

  @Override
  public SequenceType getResultType(SequenceType[] suppliedArgumentTypes) {
    return SequenceType.ANY_SEQUENCE;
  }

  @Override
  public ExtensionFunctionCall makeCallExpression() {

    return new ExtensionFunctionCall() {

      private static final long serialVersionUID = -4576064130906433346L;

      @Override
      public SequenceIterator call(SequenceIterator[] arguments,
          XPathContext context) throws XPathException {

        String q = arguments[0].next().getStringValue();
        String id = arguments[1].next().getStringValue();
        String joinVars = arguments[2].next().getStringValue();
        int pos = new Integer(arguments[3].next().getStringValue()).intValue();

        ResultSet resultSet = EvaluatorExternalFunctions.sparqlScopedDataset(q,
            id, joinVars, pos);

        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        ResultSetFormatter.outputAsXML(outputStream, resultSet);
        ByteArrayInputStream inputStream = new ByteArrayInputStream(
            outputStream.toByteArray());

        return SingletonIterator.makeIterator(context.getConfiguration()
            .buildDocument(new StreamSource(inputStream)));
      }

    };
  }

}