* 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.

*/

* <p>DatasetGraph framework : readonly dataset need only provide find(g,s,p,o), getGraph() and getDefaultGraph()

* although it may wish to override other operations and do better.</p>

*

* <p>Other implementations include:</p>

* <ul>

* <li>{@link DatasetGraphBase} that adds an implementation of find based on default / named graphs.</li>

* <li>{@link DatasetGraphCollection} that adds mutating quad operations mapped to a collection of graphs.</li>

* <li>{@link DatasetGraphQuad} that maps graph operations to a quad view.

* </ul>

*/

    private final Lock lock = new LockMRSW() ;

    private Context context = new Context() ;

   

    protected DatasetGraphBase() {}

   

    @Override

    public boolean containsGraph(Node graphNode)

    { return contains(graphNode, Node.ANY, Node.ANY, Node.ANY) ; }

   

    @Override

    public abstract Graph getDefaultGraph() ;

    @Override

    public abstract Graph getGraph(Node graphNode) ;

    @Override

    public void addGraph(Node graphName, Graph graph)

    { throw new UnsupportedOperationException("DatasetGraph.addGraph") ; }

    @Override

    public void removeGraph(Node graphName)

    { throw new UnsupportedOperationException("DatasetGraph.removeGraph") ; }

    @Override

    public void setDefaultGraph(Graph g)

    { throw new UnsupportedOperationException("DatasetGraph.setDefaultGraph") ; }

   

    @Override

    public void add(Quad quad) { throw new UnsupportedOperationException("DatasetGraph.add(Quad)") ; }

   

    @Override

    public void delete(Quad quad) { throw new UnsupportedOperationException("DatasetGraph.delete(Quad)") ; }

   

//  public void add(Node g, Node s, Node p, Node o) { throw new UnsupportedOperationException("DatasetGraph.add(Node, Node, Node, Node)") ; }

// 

//  @Override

//  public void delete(Node g, Node s, Node p, Node o) { throw new UnsupportedOperationException("DatasetGraph.delete(Node, Node, Node, Node)") ; }

    @Override

    public void add(Node g, Node s, Node p, Node o)     { add(new Quad(g,s,p,o)) ; } 

    @Override

    public void delete(Node g, Node s, Node p, Node o)  { delete(new Quad(g,s,p,o)) ; }

   

    @Override

    /** Simple implementation */

    public void deleteAny(Node g, Node s, Node p, Node o)

    {

        Iterator<Quad> iter = find(g, s, p, o) ;

        List<Quad> list = Iter.toList(iter) ;

        for ( Quad q : list )

            delete(q) ;

    }

   

    @Override

    public Iterator<Quad> find()

    { return find(Node.ANY, Node.ANY, Node.ANY, Node.ANY) ; }

   

    @Override

    public Iterator<Quad> find(Quad quad)

    {

        if ( quad == null )

            return find() ;

        return find(quad.getGraph(), quad.getSubject(), quad.getPredicate(), quad.getObject()) ; }

   

    @Override

    public boolean contains(Quad quad) { return contains(quad.getGraph(), quad.getSubject(), quad.getPredicate(), quad.getObject()) ; }

    @Override

    public boolean contains(Node g, Node s, Node p , Node o)

    {

        Iterator<Quad> iter = find(g, s, p, o) ;

        boolean b = iter.hasNext() ;

        Iter.close(iter) ;

        return b ;

    }

   

    protected static boolean isWildcard(Node g)

    {

        return g == null || g == Node.ANY ;

    }

   

    @Override

    public boolean isEmpty()

    {

        return ! contains(Node.ANY, Node.ANY, Node.ANY, Node.ANY) ;

    }

    @Override

    public long size() { return -1 ; }

   

    @Override

    public Lock getLock()

    {

        return lock ;

    }

   

    @Override

    public Context getContext()

    {

        return context ;

    }

   

    @Override

    public void close()

    { }

   

    @Override

    public String toString()

    {

        // Using the size of the graphs would be better.

        IndentedLineBuffer out = new IndentedLineBuffer() ;

        WriterGraph.output(out, this, null) ;

        return out.asString() ;

    }

    // Helpers

   

    protected static Iterator<Quad> triples2quadsDftGraph(Iterator<Triple> iter)

    {

        //return triples2quads(Quad.defaultGraphIRI, iter) ;

        return triples2quads(Quad.defaultGraphNodeGenerated, iter) ;

        //return triples2quads(Quad.tripleInQuad, iter) ;

    }

    protected static Iter<Quad> triples2quads(final Node graphNode, Iterator<Triple> iter)

    {

        Transform<Triple, Quad> transformNamedGraph = new Transform<Triple, Quad> () {

            @Override

            public Quad convert(Triple triple)

            {

                return new Quad(graphNode, triple) ;

            }

        } ;

        return Iter.iter(iter).map(transformNamedGraph) ;

    }

   

}