cz.cvut.kbss.ontodriver.sesame.SimpleListHandler Maven / Gradle / Ivy

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/**
 * 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.sesame.connector.Connector;
import cz.cvut.kbss.ontodriver.sesame.exceptions.SesameDriverException;
import cz.cvut.kbss.ontodriver.descriptor.SimpleListDescriptor;
import cz.cvut.kbss.ontodriver.descriptor.SimpleListValueDescriptor;
import cz.cvut.kbss.ontodriver.model.NamedResource;
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.*;

class SimpleListHandler extends ListHandler {

    SimpleListHandler(Connector connector, ValueFactory vf) {
        super(connector, vf);
    }

    @Override
    SesameIterator createIterator(SimpleListDescriptor listDescriptor) throws SesameDriverException {
        return new SimpleListIterator(listDescriptor, connector, vf);
    }

    @Override
    IRI createListHead(SimpleListValueDescriptor listValueDescriptor, Collection listStatements) {
        final IRI firstNode = sesameIri(listValueDescriptor.getValues().get(0).getIdentifier());
        listStatements.add(vf.createStatement(owner(listValueDescriptor), hasList(listValueDescriptor),
                firstNode, context(listValueDescriptor)));
        return firstNode;
    }

    @Override
    List createListRest(IRI head, SimpleListValueDescriptor listValueDescriptor) {
        final List statements = new ArrayList<>(listValueDescriptor.getValues().size());
        IRI previous = head;
        final IRI nextNodeProp = hasNext(listValueDescriptor);
        final IRI context = context(listValueDescriptor);
        final Iterator it = listValueDescriptor.getValues().iterator();
        it.next();
        while (it.hasNext()) {
            final IRI object = sesameIri(it.next().getIdentifier());
            statements.add(vf.createStatement(previous, nextNodeProp, object, context));
            previous = object;
        }
        return statements;
    }

    /**
     * We are using this code instead of iterator.remove for performance
     * reasons. The iterator has to reconnect the list for each removed node,
     * which takes a lot of time.
     */
    @Override
    void clearList(SimpleListValueDescriptor listValueDescriptor) throws SesameDriverException {
        final Set contexts = contexts(listValueDescriptor);
        final Collection toRemove = new ArrayList<>();
        IRI currentProperty = hasList(listValueDescriptor);
        final IRI hasNext = hasNext(listValueDescriptor);
        final boolean includeInferred = listValueDescriptor.getNextNode().isInferred();
        Collection stmts;
        Resource subject = owner(listValueDescriptor);
        do {
            stmts = connector.findStatements(subject, currentProperty, null, includeInferred, contexts);
            if (!stmts.isEmpty()) {
                subject = extractListNode(stmts, hasNext);
                toRemove.addAll(stmts);
            }
            currentProperty = hasNext;
        } while (!stmts.isEmpty());
        connector.removeStatements(toRemove);
    }

    @Override
    MergeResult mergeWithOriginalList(SimpleListValueDescriptor listDescriptor, SesameIterator it) throws
                                                                                                   SesameDriverException {
        int i = 0;
        Resource node = null;
        while (it.hasNext() && i < listDescriptor.getValues().size()) {
            node = it.nextNode();
            final NamedResource newNode = listDescriptor.getValues().get(i);
            if (!node.stringValue().equals(newNode.getIdentifier().toString())) {
                node = sesameIri(newNode.getIdentifier());
                it.replaceCurrentWith(newNode);
            }
            i++;
        }
        return new MergeResult(i, node);
    }

    @Override
    void appendNewNodes(SimpleListValueDescriptor listDescriptor, MergeResult mergeResult) throws
                                                                                           SesameDriverException {
        int i = mergeResult.i;
        final Collection toAdd = new ArrayList<>(listDescriptor.getValues().size() - i);
        Resource previous = mergeResult.previous;
        final IRI nextNode = sesameIri(listDescriptor.getNextNode().getIdentifier());
        final IRI context = context(listDescriptor);
        while (i < listDescriptor.getValues().size()) {
            final Resource newNode = sesameIri(listDescriptor.getValues().get(i).getIdentifier());
            final Statement stmt = vf.createStatement(previous, nextNode, newNode, context);
            toAdd.add(stmt);
            previous = newNode;
            i++;
        }
        connector.addStatements(toAdd);
    }

    @Override
    SesameIterator iterator(SimpleListValueDescriptor listDescriptor) throws SesameDriverException {
        return new SimpleListIterator(listDescriptor, connector, vf);
    }
}