| /** |
| * 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.commons.rdf.api; |
| |
| import java.util.Optional; |
| |
| /** |
| * A generalised "quad-like" interface, extended by {@link Quad}. |
| * <p> |
| * A QuadLike statement has at least a {@link #getSubject()}, |
| * {@link #getPredicate()}, {@link #getObject()} and {@link #getGraphName()}, |
| * but unlike a {@link Quad} does not have a formalised |
| * {@link Quad#equals(Object)} or {@link Quad#hashCode()} semantics and is not |
| * required to be <em>immutable</em> or <em>thread-safe</em>. This interface can |
| * also be used for <em>generalised quads</em> (e.g. a {@link BlankNode} as |
| * predicate). |
| * <p> |
| * Implementations should specialise which specific {@link RDFTerm} types they |
| * return by overriding {@link #getSubject()}, {@link #getPredicate()}, |
| * {@link #getObject()} and {@link #getGraphName()}. |
| * |
| * @since 0.3.0-incubating |
| * @see Quad |
| */ |
| public interface QuadLike<G extends RDFTerm> extends TripleLike { |
| |
| /** |
| * The graph name (graph label) of this statement, if present. |
| * <p> |
| * If {@link Optional#isPresent()}, then the {@link Optional#get()} indicate |
| * the graph name of this statement. If the graph name is not present,e.g. |
| * the value is {@link Optional#empty()}, it indicates that this Quad is in |
| * the default graph. |
| * |
| * @return If {@link Optional#isPresent()}, the graph name of this quad, |
| * otherwise {@link Optional#empty()}, indicating the default graph. |
| * The graph name is typically an {@link IRI} or {@link BlankNode}. |
| */ |
| Optional<G> getGraphName(); |
| |
| } |