Github user ansell commented on a diff in the pull request:
https://github.com/apache/incubator-commonsrdf/pull/24#discussion_r81665039
--- Diff:
rdf4j/src/main/java/org/apache/commons/rdf/rdf4j/impl/AbstractRepositoryGraphLike.java
---
@@ -0,0 +1,80 @@
+/**
+ * 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.rdf4j.impl;
+
+import java.util.Optional;
+
+import org.apache.commons.rdf.api.BlankNodeOrIRI;
+import org.apache.commons.rdf.api.IRI;
+import org.apache.commons.rdf.api.RDFTerm;
+import org.apache.commons.rdf.api.TripleLike;
+import org.apache.commons.rdf.rdf4j.RDF4JGraphLike;
+import org.apache.commons.rdf.rdf4j.RDF4JTermFactory;
+import org.eclipse.rdf4j.model.Model;
+import org.eclipse.rdf4j.model.Statement;
+import org.eclipse.rdf4j.repository.Repository;
+import org.eclipse.rdf4j.repository.RepositoryConnection;
+
+public abstract class AbstractRepositoryGraphLike<T extends
TripleLike<BlankNodeOrIRI, IRI, RDFTerm>>
+ implements RDF4JGraphLike<T> {
+
+ protected Repository repository;
+ protected boolean includeInferred;
+ protected boolean shouldWeShutdown = false;
+ protected RDF4JTermFactory rdf4jTermFactory;
+
+ public AbstractRepositoryGraphLike(Repository repository) {
+ this(repository, false);
+ }
+
+ public AbstractRepositoryGraphLike(Repository repository, boolean
includeInferred) {
+ this.repository = repository;
+ this.includeInferred = includeInferred;
+ if (!repository.isInitialized()) {
+ repository.initialize();
+ shouldWeShutdown = true;
+ }
+ rdf4jTermFactory = new
RDF4JTermFactory(repository.getValueFactory());
+ }
+
+ @Override
+ public void close() throws Exception {
+ if (shouldWeShutdown) {
+ repository.shutDown();
+ }
+ // else: repository was initialized outside, so we should not
shut it
+ // down
+ }
+
+
+ protected abstract T asTripleLike(Statement s);
+
+ protected RepositoryConnection getRepositoryConnection() {
+ return repository.getConnection();
+ }
+
+ public Optional<Repository> asRepository() {
+ return Optional.of(repository);
+ }
+
+ @Override
+ public Optional<Model> asModel() {
+ return Optional.empty();
--- End diff --
Returning an Optional does work to do what you want here, in the absence of
general implementations of ModelRepository and RepositoryModel to transparently
represent one as the other.
You could use a hasFeatureX/hasFeatureY pattern to avoid exceptions, but
Optional works well if the contract is clear about what Optional.empty() means.
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