Github user ansell commented on a diff in the pull request:
https://github.com/apache/incubator-commonsrdf/pull/24#discussion_r82311598
--- Diff:
rdf4j/src/main/java/org/apache/commons/rdf/rdf4j/experimental/RDF4JParser.java
---
@@ -0,0 +1,232 @@
+/**
+ * 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.experimental;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Optional;
+import java.util.function.Consumer;
+import java.util.stream.Stream;
+
+import org.apache.commons.rdf.api.IRI;
+import org.apache.commons.rdf.api.Quad;
+import org.apache.commons.rdf.api.RDFSyntax;
+import org.apache.commons.rdf.experimental.RDFParser;
+import org.apache.commons.rdf.rdf4j.RDF4JBlankNodeOrIRI;
+import org.apache.commons.rdf.rdf4j.RDF4JDataset;
+import org.apache.commons.rdf.rdf4j.RDF4JGraph;
+import org.apache.commons.rdf.rdf4j.RDF4JTermFactory;
+import org.apache.commons.rdf.simple.experimental.AbstractRDFParser;
+import org.eclipse.rdf4j.model.Model;
+import org.eclipse.rdf4j.model.Resource;
+import org.eclipse.rdf4j.repository.util.RDFInserter;
+import org.eclipse.rdf4j.repository.util.RDFLoader;
+import org.eclipse.rdf4j.rio.ParserConfig;
+import org.eclipse.rdf4j.rio.RDFFormat;
+import org.eclipse.rdf4j.rio.RDFHandler;
+import org.eclipse.rdf4j.rio.RDFHandlerException;
+import org.eclipse.rdf4j.rio.Rio;
+import org.eclipse.rdf4j.rio.helpers.AbstractRDFHandler;
+
+/**
+ * RDF4J-based parser.
+ * <p>
+ * This can handle the RDF syntaxes {@link RDFSyntax#JSONLD},
+ * {@link RDFSyntax#NQUADS}, {@link RDFSyntax#NTRIPLES},
+ * {@link RDFSyntax#RDFXML}, {@link RDFSyntax#TRIG} and {@link
RDFSyntax#TURTLE}
+ * - additional syntaxes can be supported by including the corresponding
+ * <em>rdf4j-rio-*</em> module on the classpath.
+ *
+ */
+public class RDF4JParser extends AbstractRDFParser<RDF4JParser> implements
RDFParser {
+
+ private final class AddToQuadConsumer extends AbstractRDFHandler {
+ private final Consumer<Quad> quadTarget;
+
+ private AddToQuadConsumer(Consumer<Quad> quadTarget) {
+ this.quadTarget = quadTarget;
+ }
+
+ public void handleStatement(org.eclipse.rdf4j.model.Statement
st)
+ throws
org.eclipse.rdf4j.rio.RDFHandlerException {
+ // TODO: if getRdfTermFactory() is a non-rdf4j factory,
should
+ // we use factory.createQuad() instead?
+ // Unsure what is the promise of setting
getRdfTermFactory() --
+ // does it go all the way down to creating BlankNode,
IRI and
+ // Literal?
+ quadTarget.accept(rdf4jTermFactory.asQuad(st));
+ // Performance note:
+ // Graph/Quad.add should pick up again our
+ // RDF4JGraphLike.asStatement()
+ // and avoid double conversion.
+ // Additionally the RDF4JQuad and RDF4JTriple
implementations
+ // are lazily converting subj/obj/pred/graph.s
+ }
+ }
+
+ private final static class AddToModel extends AbstractRDFHandler {
+ private final Model model;
+
+ public AddToModel(Model model) {
+ this.model = model;
+ }
+
+ public void handleStatement(org.eclipse.rdf4j.model.Statement
st)
+ throws
org.eclipse.rdf4j.rio.RDFHandlerException {
+ model.add(st);
+ }
+
+ @Override
+ public void handleNamespace(String prefix, String uri) throws
RDFHandlerException {
+ model.setNamespace(prefix, uri);
+ }
+ }
+
+ private RDF4JTermFactory rdf4jTermFactory;
+ private ParserConfig parserConfig = new ParserConfig();
+
+ @Override
+ protected RDF4JTermFactory createRDFTermFactory() {
+ return new RDF4JTermFactory();
+ }
+
+ @Override
+ protected RDF4JParser prepareForParsing() throws IOException,
IllegalStateException {
+ RDF4JParser c = prepareForParsing();
+ // Ensure we have an RDF4JTermFactory for conversion.
+ // We'll make a new one if user has provided a non-RDF4J factory
+ c.rdf4jTermFactory = (RDF4JTermFactory)
getRdfTermFactory().filter(RDF4JTermFactory.class::isInstance)
--- End diff --
It is unclear how this pattern would actually help users or have any effect
at all. Given that there are no constructors for this class, it isn't clear why
getRdfTermFactory would return anything relevant to this class at all, so it
must always in usual runtimes (without relying on brittle reflection based
methods) go through to the orElseGet and create a new factory here.
It also isn't clear why there is an instance variable here that may be
duplicating or interacting with another factory in a superclass or subclass
somewhere. That will create the ability for some really difficult bugs to pop
up that shouldn't be allowed in a strong design.
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