/*
 * 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
 *
 *   https://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.
 *
 *   SPDX-License-Identifier: Apache-2.0
 */

package org.apache.jena.rdf.model;

/**
 * The interface for visiting (ie type-dispatching) an RDF Node.
 */
public interface RDFVisitor {
    /**
     * Method to call when visiting a blank node r with identifier id.
     *
     * @param r the blank RDF node being visited
     * @param id the identifier of that node
     * @return value to be returned from the visit
     */
    Object visitBlank(Resource r, AnonId id);

    /**
     * Method to call when visiting a URI node r with the given uri.
     *
     * @param r the URI node being visited
     * @param uri the URI string of that node
     * @return value to be returned from the visit
     */
    Object visitURI(Resource r, String uri);

    /**
     * Method to call when visiting a literal RDF node l.
     *
     * @param l the RDF Literal node
     * @return a value to be returned from the visit
     */
    Object visitLiteral(Literal l);

    /**
     * Method to call when visiting a statement term.
     *
     * @param statementTerm the statement term being visited
     * @param statement the statement of that node
     * @return value to be returned from the visit
     */
    default Object visitStmt(StatementTerm statementTerm, Statement statement) { return statement; }
}
