jena-arq/src/main/java/org/apache/jena/sparql/sse/builders/BuilderGraph.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * 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,
 * 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 org.apache.jena.sparql.sse.builders;

import org.apache.jena.graph.Graph ;
import org.apache.jena.graph.Node ;
import org.apache.jena.graph.Triple ;
import org.apache.jena.riot.RDFDataMgr;
import org.apache.jena.sparql.core.DatasetGraph ;
import org.apache.jena.sparql.core.DatasetGraphFactory ;
import org.apache.jena.sparql.core.Quad ;
import org.apache.jena.sparql.graph.GraphFactory ;
import org.apache.jena.sparql.sse.Item ;
import org.apache.jena.sparql.sse.ItemList ;
import org.apache.jena.sparql.sse.Tags ;
import org.apache.jena.sparql.util.NodeUtils ;

public class BuilderGraph
{
    public static Graph buildGraph(Item item) {
        Graph graph = GraphFactory.createDefaultGraph();
        buildGraph(graph, item);
        return graph;
    }
    
    public static Graph buildGraph(ItemList itemList) {
        Graph graph = GraphFactory.createDefaultGraph();
        buildGraph(graph, itemList);
        return graph;
    }
    
    public static void buildGraph(Graph graph, Item item) {
        if ( item.isNode() )
            BuilderLib.broken(item, "Attempt to build graph from a plain node");

        if ( item.isSymbol() )
            BuilderLib.broken(item, "Attempt to build graph from a bare symbol");

        if ( item.isTagged(Tags.tagGraph) ) {
            buildGraph(graph, item.getList());
            return;
        }

        if ( item.isTagged(Tags.tagLoad) ) {
            loadGraph(graph, item.getList());
            return;
        }

        BuilderLib.broken(item, "Wanted (" + Tags.tagGraph + "...) or (" + Tags.tagLoad + "...)");
    }
    
    public static Graph buildGraph(Graph graph, ItemList list) {
        if ( !list.isEmpty() && list.get(0).isSymbol() ) {
            if ( list.get(0).isSymbol(Tags.tagGraph) )
                list = list.cdr();
        }

        for ( Item item : list ) {
            BuilderLib.checkList(item);
            Triple triple = buildTriple(item.getList());
            graph.add(triple);
        }
        return graph;
    }
    
    /** Format:
     * (dataset
     *    (graph ...))
     *    (quad ...)
     *    (g s p o)
     *    (graph IRIa ...))
     *    (graph IRIb ...))
     *    )
     * (graph ...) is an abbreviation for a dataset with a default graph and no named graphs.
     */

    public static DatasetGraph buildDataset(Item item)
    {
        return buildDataset(DatasetGraphFactory.createTxnMem(), item) ; 
    }
    
    public static DatasetGraph buildDataset(ItemList list)
    {
        return buildDataset(DatasetGraphFactory.createTxnMem(), list) ; 
    }

    public static DatasetGraph buildDataset(DatasetGraph dsg, Item item)
    {
        if (item.isNode() )
            BuilderLib.broken(item, "Attempt to build dataset from a plain node") ;

        if (item.isSymbol() )
            BuilderLib.broken(item, "Attempt to build dataset from a bare symbol") ;

        if ( item.isTagged(Tags.tagGraph) ) {
            Graph g = BuilderGraph.buildGraph(item.getList());
            return DatasetGraphFactory.create(g);
        }

        if ( ! item.isTagged(Tags.tagDataset) )
            BuilderLib.broken(item, "Wanted ("+Tags.tagDataset+"...)" );
        return buildDataset(dsg, item.getList()) ;
    }
    
    public static DatasetGraph buildDataset(DatasetGraph dsg, ItemList list) {
        BuilderLib.checkTag(list, Tags.tagDataset);
        list = list.cdr();

        for ( Item item : list ) {
            if ( !item.isTagged(Tags.tagGraph) ) {
                // Not (graph ...) so it's (quad), short form quad or an error.
                Quad q = BuilderGraph.buildQuad(item.getList(), "Expected (graph ...) or a quad () as elements of a dataset");
                dsg.add(q);
                continue;
            }

            Node name = null;
            ItemList graphContent = item.getList().cdr();

            if ( !graphContent.isEmpty() && graphContent.car().isNode() ) {
                name = graphContent.car().getNode();
                graphContent = graphContent.cdr();
            }

            Graph g;
            if ( name == null ) {
                g = dsg.getDefaultGraph();
                if ( g == null ) {
                    g = GraphFactory.createDefaultGraph();
                    dsg.setDefaultGraph(g);
                }
            } else {
                g = dsg.getGraph(name);
                if ( g == null ) {
                    g = GraphFactory.createDefaultGraph();
                    dsg.addGraph(name, g);
                }
            }
            BuilderGraph.buildGraph(g, graphContent);
        }
        return dsg;
    }
    
    private static void loadGraph(Graph graph, ItemList list) {
        BuilderLib.checkLength(2, list, Tags.tagLoad);
        Item item = list.get(1);
        if ( !item.isNode() )
            BuilderLib.broken(item, "Expected: ("+Tags.tagLoad+" 'filename')");
        String s = NodeUtils.stringLiteral(item.getNode());
        if ( s == null )
            BuilderLib.broken(item, "Expected: ("+Tags.tagLoad+" 'filename')");
        RDFDataMgr.read(graph, s);
    }

    public static Triple buildTriple(ItemList list) {
        if ( list.size() != 3 && list.size() != 4 )
            BuilderLib.broken(list, "Not a triple", list);
        if ( list.size() == 4 ) {
            if ( !list.get(0).isSymbol(Tags.tagTriple) )
                BuilderLib.broken(list, "Not a triple");
            list = list.cdr();
        }
        return _buildNode3(list);
    }

    public static Triple buildNode3(ItemList list) {
        BuilderLib.checkLength(3, list, null);
        return _buildNode3(list);
    }

    private static Triple _buildNode3(ItemList list) {
        Node s = BuilderNode.buildNode(list.get(0));
        Node p = BuilderNode.buildNode(list.get(1));
        Node o = BuilderNode.buildNode(list.get(2));
        return new Triple(s, p, o);
    }

    public static Quad buildQuad(ItemList list) {
        return buildQuad(list, "Not a quad") ;
    }
    
    public static Quad buildQuad(ItemList list, String errMsg) {
        if ( list.size() != 4 && list.size() != 5 )
            BuilderLib.broken(list, errMsg);
        if ( list.size() == 5 ) {
            if ( !list.get(0).isSymbol(Tags.tagQuad) )
                BuilderLib.broken(list, errMsg);
            list = list.cdr();
        }
        return _buildNode4(list);
    }

    public static Quad buildNode4(ItemList list) {
        BuilderLib.checkLength(4, list, null);
        return _buildNode4(list);
    }

    private static Quad _buildNode4(ItemList list) {
        Node g = null;
        if ( list.get(0).equals(Item.defaultItem) )
            g = Quad.defaultGraphNodeGenerated;
        else
            g = BuilderNode.buildNode(list.get(0));
        Node s = BuilderNode.buildNode(list.get(1));
        Node p = BuilderNode.buildNode(list.get(2));
        Node o = BuilderNode.buildNode(list.get(3));
        return new Quad(g, s, p, o);
    }
}