DatasetAssembler.java example

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/*
 * Licensed to the Apache Software Foundation (ASF) under one
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 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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,
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 * See the License for the specific language governing permissions and
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package org.apache.jena.sparql.core.assembler ;

import java.util.List ;

import org.apache.jena.assembler.Assembler ;
import org.apache.jena.assembler.Mode ;
import org.apache.jena.assembler.assemblers.AssemblerBase ;
import org.apache.jena.atlas.logging.Log ;
import org.apache.jena.query.Dataset ;
import org.apache.jena.query.DatasetFactory ;
import org.apache.jena.rdf.model.Model ;
import org.apache.jena.rdf.model.RDFNode ;
import org.apache.jena.rdf.model.Resource ;
import org.apache.jena.sparql.graph.GraphFactory ;
import org.apache.jena.sparql.util.FmtUtils ;
import org.apache.jena.sparql.util.graph.GraphUtils ;

public class DatasetAssembler extends AssemblerBase implements Assembler {
    public static Resource getType() {
        return DatasetAssemblerVocab.tDataset ;
    }

    @Override
    public Object open(Assembler a, Resource root, Mode mode) {
        Dataset ds = createDataset(a, root, mode) ;
        return ds ;
    }

    public Dataset createDataset(Assembler a, Resource root, Mode mode) {
        // -------- Default graph
        // Can use ja:graph or ja:defaultGraph
        Resource dftGraph = GraphUtils.getResourceValue(root, DatasetAssemblerVocab.pDefaultGraph) ;
        if ( dftGraph == null )
            dftGraph = GraphUtils.getResourceValue(root, DatasetAssemblerVocab.pGraph) ;

        Model dftModel = null ;
        if ( dftGraph != null )
            dftModel = a.openModel(dftGraph) ;
        else
            // Assembler description did not define one.
            dftModel = GraphFactory.makeDefaultModel() ;
        Dataset ds = DatasetFactory.create(dftModel) ;
        // -------- Named graphs
        List<RDFNode> nodes = GraphUtils.multiValue(root, DatasetAssemblerVocab.pNamedGraph) ;
        for ( RDFNode n : nodes ) {
            if ( !(n instanceof Resource) )
                throw new DatasetAssemblerException(root, "Not a resource: " + FmtUtils.stringForRDFNode(n));
            Resource r = (Resource)n;

            String gName = GraphUtils.getAsStringValue(r, DatasetAssemblerVocab.pGraphName);
            Resource g = GraphUtils.getResourceValue(r, DatasetAssemblerVocab.pGraph);
            if ( g == null ) {
                g = GraphUtils.getResourceValue(r, DatasetAssemblerVocab.pGraphAlt);
                if ( g != null ) {
                    Log.warn(this, "Use of old vocabulary: use :graph not :graphData");
                } else {
                    throw new DatasetAssemblerException(root, "no graph for: " + gName);
                }
            }

            Model m = a.openModel(g);
            ds.addNamedModel(gName, m);
        }
        AssemblerUtils.setContext(root, ds.getContext()) ;
        return ds ;
    }
}