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https://issues.apache.org/jira/browse/COMMONSRDF-35?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15544127#comment-15544127
]
ASF GitHub Bot commented on COMMONSRDF-35:
------------------------------------------
Github user stain commented on a diff in the pull request:
https://github.com/apache/incubator-commonsrdf/pull/24#discussion_r81678453
--- Diff:
rdf4j/src/main/java/org/apache/commons/rdf/rdf4j/RDF4JTermFactory.java ---
@@ -0,0 +1,509 @@
+/**
+ * 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;
+
+import java.util.UUID;
+
+// To avoid confusion, avoid importing
+// classes that are in both
+// commons.rdf and openrdf.model (e.g. IRI)
+import org.apache.commons.rdf.api.BlankNode;
+import org.apache.commons.rdf.api.BlankNodeOrIRI;
+import org.apache.commons.rdf.api.Dataset;
+import org.apache.commons.rdf.api.Graph;
+import org.apache.commons.rdf.api.IRI;
+import org.apache.commons.rdf.api.Quad;
+import org.apache.commons.rdf.api.RDFTerm;
+import org.apache.commons.rdf.api.RDFTermFactory;
+import org.apache.commons.rdf.api.Triple;
+import org.apache.commons.rdf.api.TripleLike;
+import org.apache.commons.rdf.rdf4j.impl.BlankNodeImpl;
+import org.apache.commons.rdf.rdf4j.impl.IRIImpl;
+import org.apache.commons.rdf.rdf4j.impl.LiteralImpl;
+import org.apache.commons.rdf.rdf4j.impl.ModelGraphImpl;
+import org.apache.commons.rdf.rdf4j.impl.QuadImpl;
+import org.apache.commons.rdf.rdf4j.impl.RepositoryDatasetImpl;
+import org.apache.commons.rdf.rdf4j.impl.RepositoryGraphImpl;
+import org.apache.commons.rdf.rdf4j.impl.TripleImpl;
+import org.eclipse.rdf4j.model.BNode;
+import org.eclipse.rdf4j.model.Model;
+import org.eclipse.rdf4j.model.Statement;
+import org.eclipse.rdf4j.model.Value;
+import org.eclipse.rdf4j.model.ValueFactory;
+import org.eclipse.rdf4j.model.impl.LinkedHashModel;
+import org.eclipse.rdf4j.model.impl.SimpleValueFactory;
+import org.eclipse.rdf4j.repository.Repository;
+
+/**
+ * RDF4J implementation of RDFTermFactory
+ * <p>
+ * The {@link #RDF4JTermFactory()} constructor uses a {@link
SimpleValueFactory}
+ * to create corresponding RDF4J {@link Value} instances. Alternatively,
this
+ * factory can be constructed with a different {@link ValueFactory} using
+ * {@link #RDF4JTermFactory(ValueFactory)}.
+ * <p>
+ * {@link #asRDFTerm(Value)} can be used to convert any RDF4J {@link
Value} to
+ * an RDFTerm. Note that adapted {@link BNode}s are considered equal if
they are
+ * converted with the same {@link RDF4JTermFactory} instance and have the
same
+ * {@link BNode#getID()}.
+ * <p>
+ * {@link #createGraph()} creates a new Graph backed by {@link
LinkedHashModel}.
+ * To use other models, see {@link #asRDFTermGraph(Model)}.
+ * <p>
+ * To adapt a RDF4J {@link Repository} as a {@link Dataset} or {@link
Graph},
+ * use {@link #asRDFTermDataset(Repository)} or
+ * {@link #asRDFTermGraph(Repository)}.
+ * <p>
+ * {@link #asTriple(Statement)} can be used to convert a RDF4J {@link
Statement}
+ * to a Commons RDF {@link Triple}, and equivalent {@link
#asQuad(Statement)} to
+ * convert a {@link Quad}.
+ * <p>
+ * To convert any {@link Triple} or {@link Quad} to to RDF4J {@link
Statement},
+ * use {@link #asStatement(TripleLike)}. This recognises previously
converted
+ * {@link RDF4JTriple}s and {@link RDF4JQuad}s without re-converting their
+ * {@link RDF4JTripleLike#asStatement()}.
+ * <p>
+ * Likewise, {@link #asValue(RDFTerm)} can be used to convert any Commons
RDF
+ * {@link RDFTerm} to a corresponding RDF4J {@link Value}. This recognises
+ * previously converted {@link RDF4JTerm}s without re-converting their
+ * {@link RDF4JTerm#asValue()}.
+ * <p>
+ * For the purpose of {@link BlankNode} equivalence, this factory contains
an
+ * internal {@link UUID} salt that is used by adapter methods like
+ * {@link #asQuad(Statement)}, {@link #asTriple(Statement)},
+ * {@link #asRDFTerm(Value)} as well as {@link #createBlankNode(String)}.
As
+ * RDF4J {@link BNode} instances from multiple repositories or models may
have
+ * the same {@link BNode#getID()}, converting them with the above methods
might
+ * cause accidental {@link BlankNode} equivalence. Note that the {@link
Graph}
+ * and {@link Dataset} adapter methods like
+ * {@link #asRDFTermDataset(Repository)} and {@link #asRDFTermGraph(Model)}
+ * therefore uses a unique {@link RDF4JTermFactory} internally. An
alternative
+ * is to use the static methods {@link #asRDFTerm(Value, UUID)},
+ * {@link #asQuad(Statement, UUID)} or {@link #asTriple(Statement, UUID)}
with
+ * a provided {@link UUID} salt.
+ *
+ */
+public class RDF4JTermFactory implements RDFTermFactory {
+
+ /**
+ * Adapt a RDF4J {@link Value} as a Commons RDF {@link RDFTerm}.
+ * <p>
+ * The value will be of the same kind as the term, e.g. a
+ * {@link org.eclipse.rdf4j.model.BNode} is converted to a
+ * {@link org.apache.commons.rdf.api.BlankNode}, a
+ * {@link org.eclipse.rdf4j.model.IRI} is converted to a
+ * {@link org.apache.commons.rdf.api.IRI} and a
+ * {@link org.eclipse.rdf4j.model.Literal}. is converted to a
+ * {@link org.apache.commons.rdf.api.Literal}
+ *
+ * @param value
+ * The RDF4J {@link Value} to convert.
+ * @param salt
+ * A {@link UUID} salt to use for uniquely mapping any
+ * {@link BNode}s. The salt should typically be the same for
+ * multiple statements in the same {@link Repository} or
+ * {@link Model} to ensure {@link BlankNode#equals(Object)}
and
+ * {@link BlankNode#uniqueReference()} works as intended.
+ * @param <T>
+ * The subclass of {@link Value}, e.g. {@link BNode}
+ * @return A {@link RDFTerm} that corresponds to the RDF4J value
+ * @throws IllegalArgumentException
+ * if the value is not a BNode, Literal or IRI
+ */
+ @SuppressWarnings("unchecked")
+ public static <T extends Value> RDF4JTerm<T> asRDFTerm(final T value,
UUID salt) {
+ if (value instanceof BNode) {
+ return (RDF4JTerm<T>) new BlankNodeImpl((BNode) value,
salt);
+ }
+ if (value instanceof org.eclipse.rdf4j.model.Literal) {
+ return (RDF4JTerm<T>) new
LiteralImpl((org.eclipse.rdf4j.model.Literal) value);
+ }
+ if (value instanceof org.eclipse.rdf4j.model.IRI) {
+ return (RDF4JTerm<T>) new
IRIImpl((org.eclipse.rdf4j.model.IRI) value);
+ }
+ throw new IllegalArgumentException("Value is not a BNode,
Literal or IRI: " + value.getClass());
+ }
+
+ /**
+ * Adapt a RDF4J {@link Statement} as a Commons RDF {@link Triple}.
+ *
+ * @param statement
+ * The statement to convert
+ * @param salt
+ * A {@link UUID} salt to use for uniquely mapping any
+ * {@link BNode}s. The salt should typically be the same for
+ * multiple statements in the same {@link Repository} or
+ * {@link Model} to ensure {@link BlankNode#equals(Object)}
and
+ * {@link BlankNode#uniqueReference()} works as intended.
+ * @return A {@link Triple} that corresponds to the RDF4J statement
+ */
+ public static RDF4JTriple asTriple(final Statement statement, UUID
salt) {
+ return new TripleImpl(statement, salt);
+ }
+
+ private UUID salt = UUID.randomUUID();
+
+ private final ValueFactory valueFactory;
+
+ public RDF4JTermFactory() {
+ this.valueFactory = SimpleValueFactory.getInstance();
+ }
+
+ public RDF4JTermFactory(ValueFactory valueFactory) {
+ this.valueFactory = valueFactory;
+ }
+
+ /**
+ * Adapt a RDF4J {@link Statement} as a Commons RDF {@link Quad}.
+ * <p>
+ * For the purpose of {@link BlankNode} equivalence, this
+ * method will use an internal salt UUID that is unique per instance of
+ * {@link RDF4JTermFactory}.
+ * <p>
+ * <strong>NOTE:</strong> If combining RDF4J {@link Statement}s
+ * multiple repositories or models, then their {@link BNode}s
+ * may have the same {@link BNode#getID()}, which with this method
+ * would become equivalent according to {@link
BlankNode#equals(Object)} and
+ * {@link BlankNode#uniqueReference()},
+ * unless a separate {@link RDF4JTermFactory}
+ * instance is used per RDF4J repository/model.
+ *
+ * @see #asQuad(Statement, UUID)
+ * @param statement
+ * The statement to convert
+ * @return A {@link RDF4JQuad} that is equivalent to the statement
+ */
+ public RDF4JQuad asQuad(final Statement statement) {
+ return new QuadImpl(statement, salt);
--- End diff --
I've removed all except `asValue(Node, UUID)` in the factory. This is
needed from `Quad` and `Triple` as they (at least now) generate on demand their
RDFTerm instances of getSubject() etc.
Not sure why `java.util.UUID` is considered brittle, it's immutable. :-) I
think now with the constructors hidden it's minimized how to 'do the wrong
thing'. I added javadoc for the RDF4JTermFactory constructor
If `Triple` and `Quad` instead keep the `RDF4JTermFactory` it means they
also hold a reference to the `ValueFactory` (which they don't need) - remember
a Triple or Quad is what could make itself way into "other" code and so I
wanted them to have as little references as possible.
A `java.util.UUID` is quite a small object (final class, two longs) - and
if for some reason needed, the code could even be optimized to keep those longs
directly in the QuadImpl/TripleImpl. Or they could cache/pregenerate their
getSubject/getPredicate/getObject() and not need any of the references-- it's
hard to tell at this stage what is the best optimization.
> rdf4j integration
> -----------------
>
> Key: COMMONSRDF-35
> URL: https://issues.apache.org/jira/browse/COMMONSRDF-35
> Project: Apache Commons RDF
> Issue Type: New Feature
> Reporter: Stian Soiland-Reyes
> Assignee: Stian Soiland-Reyes
> Labels: integration, rdf4j, sesame
> Fix For: 0.3.0
>
>
> Add a new rdf4j module with implementation for Eclipse rdf4j
> See https://github.com/apache/incubator-commonsrdf/tree/rdf4j/rdf4j
> A legacy sesame branch could then be added by mainly copy/paste and change
> the import
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