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Sesame implementation of the OntoDriver API
There is a newer version: 0.22.2
/**
 * Copyright (C) 2020 Czech Technical University in Prague
 * 
 * This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later
 * version.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
 * details. You should have received a copy of the GNU General Public License along with this program. If not, see
 * .
 */
package cz.cvut.kbss.ontodriver.sesame;

import cz.cvut.kbss.ontodriver.descriptor.SimpleListDescriptor;
import cz.cvut.kbss.ontodriver.model.Assertion;
import cz.cvut.kbss.ontodriver.model.Axiom;
import cz.cvut.kbss.ontodriver.model.NamedResource;
import cz.cvut.kbss.ontodriver.sesame.connector.Connector;
import cz.cvut.kbss.ontodriver.sesame.exceptions.SesameDriverException;
import org.eclipse.rdf4j.model.IRI;
import org.eclipse.rdf4j.model.Resource;
import org.eclipse.rdf4j.model.Statement;
import org.eclipse.rdf4j.model.ValueFactory;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

class SimpleListIterator extends AbstractSesameIterator {

    private final SimpleListDescriptor listDescriptor;

    private IRI currentProperty;

    private Statement current;
    private Collection next;

    public SimpleListIterator(SimpleListDescriptor listDescriptor, Connector connector, ValueFactory vf)
            throws SesameDriverException {
        super(listDescriptor, connector, vf);
        this.listDescriptor = listDescriptor;
        this.currentProperty = hasListProperty;
        init();
    }

    private void init() throws SesameDriverException {
        this.next = connector.findStatements(listOwner, hasListProperty, null, includeInferred, contexts());
    }

    @Override
    public boolean hasNext() {
        return !next.isEmpty();
    }

    @Override
    public Resource nextNode() throws SesameDriverException {
        nextInternal();
        assert current.getObject() instanceof Resource;

        return (Resource) current.getObject();
    }

    private void nextInternal() throws SesameDriverException {
        if (!hasNext()) {
            throw new IllegalStateException();
        }
        checkSuccessorMax(next, currentProperty);
        this.current = next.iterator().next();
        this.currentProperty = current.getPredicate();
        checkNodeIsResource(current);
        final Resource elem = (Resource) current.getObject();
        this.next = connector.findStatements(elem, hasNextProperty, null, includeInferred, contexts());
    }

    @Override
    public Resource currentContent() {
        assert current.getObject() instanceof Resource;

        return (Resource) current.getObject();
    }

    @Override
    public Axiom nextAxiom() throws SesameDriverException {
        nextInternal();
        assert current.getObject() instanceof Resource;

        final Assertion assertion = current.getPredicate() == hasListProperty ? listDescriptor
                .getListProperty() : listDescriptor.getNextNode();
        return createAxiom(current.getSubject(), assertion, (Resource) current.getObject());
    }

    @Override
    public void replaceCurrentWith(NamedResource newNode) throws SesameDriverException {
        assert current.getObject() instanceof Resource;
        final Resource newNodeSesame = vf.createIRI(newNode.getIdentifier().toString());
        final List toAdd = new ArrayList<>(2);
        final List toRemove = new ArrayList<>(2);
        toRemove.add(current);
        final Statement newCurrent = vf.createStatement(current.getSubject(), currentProperty,
                newNodeSesame, context);
        // From the current subject to the new node
        toAdd.add(newCurrent);
        if (hasNext()) {
            toRemove.addAll(next);
            final Statement stmt = next.iterator().next();
            checkNodeIsResource(stmt);
            final Resource nextNode = (Resource) stmt.getObject();
            if (!newNodeSesame.equals(nextNode)) {
                // From the new node to the next node
                final Statement newNext = vf.createStatement(newNodeSesame, hasNextProperty,
                        nextNode, context);
                toAdd.add(newNext);
                this.next = Collections.singletonList(newNext);
            } else {
                this.next = connector.findStatements(newNodeSesame, hasNextProperty, null,
                        includeInferred, contexts());
            }
        } else {
            this.next = Collections.emptyList();
        }
        this.current = null;
        connector.removeStatements(toRemove);
        connector.addStatements(toAdd);
    }

    @Override
    public void remove() throws SesameDriverException {
        assert current.getObject() instanceof Resource;
        final Collection toRemove = new ArrayList<>(next.size() + 1);
        toRemove.add(current);
        if (hasNext()) {
            toRemove.addAll(next);
            final Statement stmt = next.iterator().next();
            checkNodeIsResource(stmt);
            final Resource nextNode = (Resource) stmt.getObject();
            // Here we use the current property, so that it can also be the
            // hasList property
            final Statement toAdd = vf.createStatement(current.getSubject(), currentProperty,
                    nextNode, context);
            this.next = Collections.singletonList(toAdd);
            this.current = null;

            connector.addStatements(next);
        } else {
            this.next = Collections.emptyList();
        }
        connector.removeStatements(toRemove);
    }
}