[Enhancement #206] Refactor RDF4J list handling to support data prope…

…rty values in referenced lists. Signed-off-by: Martin Ledvinka <[email protected]>
kbss-cvut · Nov 26, 2023 · a1f10ba · a1f10ba
1 parent 6591917
commit a1f10ba
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Showing 15 changed files with 272 additions and 269 deletions.
diff --git a/ontodriver-rdf4j/src/main/java/cz/cvut/kbss/ontodriver/rdf4j/ListHandler.java b/ontodriver-rdf4j/src/main/java/cz/cvut/kbss/ontodriver/rdf4j/ListHandler.java
@@ -17,118 +17,44 @@
  */
 package cz.cvut.kbss.ontodriver.rdf4j;
 
-import cz.cvut.kbss.ontodriver.descriptor.*;
+import cz.cvut.kbss.ontodriver.descriptor.ListDescriptor;
 import cz.cvut.kbss.ontodriver.exception.IntegrityConstraintViolatedException;
-import cz.cvut.kbss.ontodriver.model.Axiom;
-import cz.cvut.kbss.ontodriver.model.NamedResource;
 import cz.cvut.kbss.ontodriver.rdf4j.connector.Connector;
 import cz.cvut.kbss.ontodriver.rdf4j.exception.Rdf4jDriverException;
 import cz.cvut.kbss.ontodriver.rdf4j.util.Rdf4jUtils;
-import org.eclipse.rdf4j.model.*;
+import org.eclipse.rdf4j.model.IRI;
+import org.eclipse.rdf4j.model.Resource;
+import org.eclipse.rdf4j.model.Statement;
+import org.eclipse.rdf4j.model.Value;
+import org.eclipse.rdf4j.model.ValueFactory;
 
-import java.util.*;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Set;
 
 /**
  * Base class for list handlers.
  * <p>
  * List handlers are responsible for loading and persisting lists.
- *
- * @param <T> List descriptor type
- * @param <V> List value descriptor type
  */
-abstract class ListHandler<T extends ListDescriptor, V extends ListValueDescriptor<?>> {
+abstract class ListHandler {
 
-    protected final Connector connector;
-    protected final ValueFactory vf;
+    final Connector connector;
+    final ValueFactory vf;
 
     ListHandler(Connector connector, ValueFactory vf) {
         this.connector = connector;
         this.vf = vf;
     }
 
-    /**
-     * Loads axioms representing list described by the specified list descriptor.
-     *
-     * @return Collection of axioms representing sequence values
-     * @throws Rdf4jDriverException When storage access error occurs
-     */
-    List<Axiom<NamedResource>> loadList(T listDescriptor) throws Rdf4jDriverException {
-        final List<Axiom<NamedResource>> axioms = new ArrayList<>();
-        final ListIterator<?> it = createIterator(listDescriptor);
-        while (it.hasNext()) {
-            axioms.add(it.nextAxiom());
-        }
-        return axioms;
-    }
-
-    abstract ListIterator<?> createIterator(T listDescriptor) throws Rdf4jDriverException;
-
-    /**
-     * Persists list values specified by the descriptor.
-     * <p>
-     * The values are saved in the order in which they appear in the descriptor.
-     *
-     * @param listValueDescriptor Describes values to persist
-     * @throws Rdf4jDriverException When storage access error occurs
-     */
-    void persistList(V listValueDescriptor) throws Rdf4jDriverException {
-        if (listValueDescriptor.getValues().isEmpty()) {
-            return;
-        }
-        final Collection<Statement> statements = new ArrayList<>(listValueDescriptor.getValues().size());
-        final IRI head = createListHead(listValueDescriptor, statements);
-        statements.addAll(createListRest(head, listValueDescriptor));
-        connector.addStatements(statements);
-    }
-
-    abstract IRI createListHead(V valueDescriptor, Collection<Statement> listStatements) throws Rdf4jDriverException;
-
-    abstract List<Statement> createListRest(IRI head, V valueDescriptor) throws Rdf4jDriverException;
-
-    /**
-     * Updates list with values specified by the descriptor.
-     *
-     * @param listValueDescriptor Describes the updated values
-     * @throws Rdf4jDriverException When storage access error occurs
-     */
-    void updateList(V listValueDescriptor) throws Rdf4jDriverException {
-        if (listValueDescriptor.getValues().isEmpty()) {
-            clearList(listValueDescriptor);
-        } else if (isOldListEmpty(owner(listValueDescriptor), hasList(listValueDescriptor),
-                listValueDescriptor.getListProperty().isInferred(), contexts(listValueDescriptor))) {
-            persistList(listValueDescriptor);
-        } else {
-            mergeList(listValueDescriptor);
-        }
-    }
-
-    private boolean isOldListEmpty(Resource owner, IRI hasListProperty, boolean includeInferred,
+    boolean isOldListEmpty(Resource owner, IRI hasListProperty, boolean includeInferred,
                                    Set<IRI> contexts) throws Rdf4jDriverException {
         final Collection<Statement> stmts = connector.findStatements(owner, hasListProperty, null,
                 includeInferred, contexts);
         return stmts.isEmpty();
     }
 
-    abstract void clearList(V listDescriptor) throws Rdf4jDriverException;
-
-    private void mergeList(V listDescriptor) throws Rdf4jDriverException {
-        final ListIterator<?> it = iterator(listDescriptor);
-        final MergeResult mergeResult = mergeWithOriginalList(listDescriptor, it);
-        removeObsoletes(it);
-        assert mergeResult.i > 0;
-        assert mergeResult.previous != null;
-        if (mergeResult.i < listDescriptor.getValues().size()) {
-            appendNewNodes(listDescriptor, mergeResult);
-        }
-    }
-
-    abstract ListIterator<?> iterator(V listDescriptor) throws Rdf4jDriverException;
-
-    abstract MergeResult mergeWithOriginalList(V listDescriptor, ListIterator<?> it) throws Rdf4jDriverException;
-
-    abstract void appendNewNodes(V listDescriptor, MergeResult mergeResult) throws Rdf4jDriverException;
-
-    private void removeObsoletes(ListIterator<?> it) throws Rdf4jDriverException {
+    void removeObsoletes(ListIterator<?> it) throws Rdf4jDriverException {
         while (it.hasNext()) {
             it.nextNode();
             it.remove();
@@ -174,35 +100,6 @@ IRI toRdf4jIri(java.net.URI uri) {
         return Rdf4jUtils.toRdf4jIri(uri, vf);
     }
 
-    /**
-     * Creates handler for simple lists.
-     *
-     * @param connector Storage connector
-     * @param vf        RDF4J value factory
-     * @return List handler
-     */
-    static ListHandler<SimpleListDescriptor, SimpleListValueDescriptor> createForSimpleList(
-            Connector connector, ValueFactory vf) {
-        assert connector != null;
-        assert vf != null;
-
-        return new SimpleListHandler(connector, vf);
-    }
-
-    /**
-     * Creates handler for referenced lists.
-     *
-     * @param connector Storage connector
-     * @param vf        RDF4J value factory
-     * @return List handler
-     */
-    static ListHandler<ReferencedListDescriptor, ReferencedListValueDescriptor<?>> createForReferencedList(
-            Connector connector, ValueFactory vf) {
-        assert connector != null;
-        assert vf != null;
-
-        return new ReferencedListHandler(connector, vf);
-    }
 
     static final class MergeResult {
         final int i;

diff --git a/ontodriver-rdf4j/src/main/java/cz/cvut/kbss/ontodriver/rdf4j/Rdf4jAdapter.java b/ontodriver-rdf4j/src/main/java/cz/cvut/kbss/ontodriver/rdf4j/Rdf4jAdapter.java
@@ -19,11 +19,11 @@
 
 import cz.cvut.kbss.ontodriver.Closeable;
 import cz.cvut.kbss.ontodriver.Wrapper;
-import cz.cvut.kbss.ontodriver.descriptor.*;
+import cz.cvut.kbss.ontodriver.descriptor.AxiomDescriptor;
+import cz.cvut.kbss.ontodriver.descriptor.AxiomValueDescriptor;
 import cz.cvut.kbss.ontodriver.exception.IdentifierGenerationException;
 import cz.cvut.kbss.ontodriver.exception.OntoDriverException;
 import cz.cvut.kbss.ontodriver.model.Axiom;
-import cz.cvut.kbss.ontodriver.model.NamedResource;
 import cz.cvut.kbss.ontodriver.rdf4j.config.Constants;
 import cz.cvut.kbss.ontodriver.rdf4j.config.RuntimeConfiguration;
 import cz.cvut.kbss.ontodriver.rdf4j.connector.Connector;
@@ -39,7 +39,11 @@
 import org.eclipse.rdf4j.model.vocabulary.RDF;
 
 import java.net.URI;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
 import java.util.stream.Collectors;
 
 class Rdf4jAdapter implements Closeable, Wrapper {
@@ -210,15 +214,15 @@ StatementExecutor getQueryExecutor() {
         return connector;
     }
 
-    ListHandler<SimpleListDescriptor, SimpleListValueDescriptor, NamedResource> getSimpleListHandler() throws Rdf4jDriverException {
+    SimpleListHandler getSimpleListHandler() throws Rdf4jDriverException {
         startTransactionIfNotActive();
-        return ListHandler.createForSimpleList(connector, valueFactory);
+        return new SimpleListHandler(connector, valueFactory);
     }
 
-    ListHandler<ReferencedListDescriptor, ReferencedListValueDescriptor<?>, ?> getReferencedListHandler() throws
+    ReferencedListHandler getReferencedListHandler() throws
             Rdf4jDriverException {
         startTransactionIfNotActive();
-        return ListHandler.createForReferencedList(connector, valueFactory);
+        return new ReferencedListHandler(connector, valueFactory);
     }
 
     TypesHandler getTypesHandler() throws Rdf4jDriverException {

diff --git a/ontodriver-rdf4j/src/main/java/cz/cvut/kbss/ontodriver/rdf4j/Rdf4jLists.java b/ontodriver-rdf4j/src/main/java/cz/cvut/kbss/ontodriver/rdf4j/Rdf4jLists.java
@@ -84,7 +84,7 @@ public <T> void persistReferencedList(ReferencedListValueDescriptor<T> descripto
     }
 
     @Override
-    public void updateReferencedList(ReferencedListValueDescriptor descriptor)
+    public <T> void updateReferencedList(ReferencedListValueDescriptor<T> descriptor)
             throws OntoDriverException {
         verifyArgs(descriptor);
         adapter.getReferencedListHandler().updateList(descriptor);