changed the request processor classes to use the new generic TriplePatternElement interface

Olaf Hartig · Olaf Hartig · commit be6576859ec3 · 2015-12-25T17:39:19.000+01:00
diff --git a/src/org/linkeddatafragments/datasource/AbstractRequestProcessorForTriplePatterns.java b/src/org/linkeddatafragments/datasource/AbstractRequestProcessorForTriplePatterns.java
@@ -1,41 +1,52 @@
 package org.linkeddatafragments.datasource;
 
+import com.hp.hpl.jena.rdf.model.Model;
+
 import org.linkeddatafragments.fragments.LinkedDataFragment;
 import org.linkeddatafragments.fragments.LinkedDataFragmentRequest;
+import org.linkeddatafragments.fragments.tpf.TriplePatternElement;
 import org.linkeddatafragments.fragments.tpf.TriplePatternFragment;
 import org.linkeddatafragments.fragments.tpf.TriplePatternFragmentImpl;
 import org.linkeddatafragments.fragments.tpf.TriplePatternFragmentRequest;
 
-import com.hp.hpl.jena.rdf.model.Model;
-
 /**
  * Base class for implementations of {@link IFragmentRequestProcessor} that
  * process {@link TriplePatternFragmentRequest}s.
  *
+ * @param <TermType> type for representing RDF terms in triple patterns 
+ * @param <VarType> type for representing specific variables in triple patterns
+ *
  * @author <a href="http://olafhartig.de">Olaf Hartig</a>
  */
-public abstract class AbstractRequestProcessorForTriplePatterns
-    extends AbstractRequestProcessor
+public abstract class
+    AbstractRequestProcessorForTriplePatterns<TermType,VarType>
+        extends AbstractRequestProcessor
 {
     @Override
-    protected Worker getWorker( final LinkedDataFragmentRequest request )
+    protected final Worker<TermType,VarType> getWorker(
+            final LinkedDataFragmentRequest request )
                                                 throws IllegalArgumentException
     {
-        if ( request instanceof TriplePatternFragmentRequest )
-            return getWorker( (TriplePatternFragmentRequest) request );
+        if ( request instanceof TriplePatternFragmentRequest<?,?> ) {
+            @SuppressWarnings("unchecked")
+            final TriplePatternFragmentRequest<TermType,VarType> tpfRequest =
+                      (TriplePatternFragmentRequest<TermType,VarType>) request;
+            return getTPFSpecificWorker( tpfRequest );
+        }
         else
             throw new IllegalArgumentException( request.getClass().getName() );
     }
 
-    abstract protected Worker getWorker(
-            final TriplePatternFragmentRequest request )
+    abstract protected Worker<TermType,VarType> getTPFSpecificWorker(
+            final TriplePatternFragmentRequest<TermType,VarType> request )
                     throws IllegalArgumentException;
 
 
-    abstract static protected class Worker
+    abstract static protected class Worker<TermType,VarType>
         extends AbstractRequestProcessor.Worker
     {        
-        public Worker( final TriplePatternFragmentRequest request )
+        public Worker(
+                 final TriplePatternFragmentRequest<TermType,VarType> request )
         {
             super( request );
         }
@@ -51,20 +62,22 @@ public LinkedDataFragment createRequestedFragment()
             else
                 offset = 0L;
 
-            final TriplePatternFragmentRequest tpfRequest =
-                                        (TriplePatternFragmentRequest) request;
+            @SuppressWarnings("unchecked")
+            final TriplePatternFragmentRequest<TermType,VarType> tpfRequest =
+                      (TriplePatternFragmentRequest<TermType,VarType>) request;
 
             return createFragment( tpfRequest.getSubject(),
                                    tpfRequest.getPredicate(),
                                    tpfRequest.getObject(),
                                    offset, limit );
         }
 
-        abstract protected LinkedDataFragment createFragment( final String subj,
-                                                              final String pred,
-                                                              final String obj,
-                                                              final long offset,
-                                                              final long limit )
+        abstract protected LinkedDataFragment createFragment(
+                            final TriplePatternElement<TermType,VarType> subj,
+                            final TriplePatternElement<TermType,VarType> pred,
+                            final TriplePatternElement<TermType,VarType> obj,
+                            final long offset,
+                            final long limit )
                                                throws IllegalArgumentException;
 
         protected TriplePatternFragment createEmptyTriplePatternFragment()
@@ -78,17 +91,11 @@ protected TriplePatternFragment createTriplePatternFragment(
                                                      final long totalSize,
                                                      final boolean isLastPage )
         {
-            final long pageNumber;
-            if ( request.isPageRequest() )
-                pageNumber = request.getPageNumber();
-            else
-                pageNumber = 1L;
-
             return new TriplePatternFragmentImpl( triples,
                                                   totalSize,
                                                   request.getFragmentURL(),
                                                   request.getDatasetURL(),
-                                                  pageNumber,
+                                                  request.getPageNumber(),
                                                   isLastPage );
         }
 
diff --git a/src/org/linkeddatafragments/datasource/hdt/HdtBasedRequestProcessorForTPFs.java b/src/org/linkeddatafragments/datasource/hdt/HdtBasedRequestProcessorForTPFs.java
@@ -2,9 +2,10 @@
 
 import java.io.IOException;
 
-import org.linkeddatafragments.datasource.AbstractJenaBasedRequestProcessorForTriplePatterns;
+import org.linkeddatafragments.datasource.AbstractRequestProcessorForTriplePatterns;
 import org.linkeddatafragments.datasource.IFragmentRequestProcessor;
 import org.linkeddatafragments.fragments.LinkedDataFragment;
+import org.linkeddatafragments.fragments.tpf.TriplePatternElement;
 import org.linkeddatafragments.fragments.tpf.TriplePatternFragmentRequest;
 import org.rdfhdt.hdt.enums.TripleComponentRole;
 import org.rdfhdt.hdt.hdt.HDT;
@@ -16,9 +17,7 @@
 import com.hp.hpl.jena.graph.Triple;
 import com.hp.hpl.jena.rdf.model.Model;
 import com.hp.hpl.jena.rdf.model.ModelFactory;
-import com.hp.hpl.jena.rdf.model.Property;
 import com.hp.hpl.jena.rdf.model.RDFNode;
-import com.hp.hpl.jena.rdf.model.Resource;
 
 /**
  * Implementation of {@link IFragmentRequestProcessor} that processes
@@ -28,7 +27,7 @@
  * @author <a href="http://olafhartig.de">Olaf Hartig</a>
  */
 public class HdtBasedRequestProcessorForTPFs
-    extends AbstractJenaBasedRequestProcessorForTriplePatterns
+    extends AbstractRequestProcessorForTriplePatterns<RDFNode,String>
 {
     protected final HDT datasource;
     protected final NodeDictionary dictionary;
@@ -46,31 +45,38 @@ public HdtBasedRequestProcessorForTPFs( String hdtFile ) throws IOException
     }
 
     @Override
-    protected Worker getWorker( final TriplePatternFragmentRequest request )
+    protected Worker getTPFSpecificWorker(
+            final TriplePatternFragmentRequest<RDFNode,String> request )
                                                 throws IllegalArgumentException
     {
         return new Worker( request );
     }
 
 
     protected class Worker
-        extends AbstractJenaBasedRequestProcessorForTriplePatterns.Worker
+       extends AbstractRequestProcessorForTriplePatterns.Worker<RDFNode,String>
     {
-        public Worker( final TriplePatternFragmentRequest request ) {
-            super( request );
+        public Worker( final TriplePatternFragmentRequest<RDFNode,String> req )
+        {
+            super( req );
         }
 
         @Override
-        protected LinkedDataFragment createFragment( final Resource subject,
-                                                     final Property predicate,
-                                                     final RDFNode object,
-                                                     final long offset,
-                                                     final long limit )
+        protected LinkedDataFragment createFragment(
+                          final TriplePatternElement<RDFNode,String> subject,
+                          final TriplePatternElement<RDFNode,String> predicate,
+                          final TriplePatternElement<RDFNode,String> object,
+                          final long offset,
+                          final long limit )
         {
+            // FIXME: The following algorithm is incorrect for cases in which
+            //        the requested triple pattern contains a specific variable
+            //        multiple times (e.g., ?x foaf:knows ?x ).
+
             // look up the result from the HDT datasource)
-            int subjectId = subject == null ? 0 : dictionary.getIntID(subject.asNode(), TripleComponentRole.SUBJECT);
-            int predicateId = predicate == null ? 0 : dictionary.getIntID(predicate.asNode(), TripleComponentRole.PREDICATE);
-            int objectId = object == null ? 0 : dictionary.getIntID(object.asNode(), TripleComponentRole.OBJECT);
+            int subjectId = subject.isVariable() ? 0 : dictionary.getIntID(subject.asTerm().asNode(), TripleComponentRole.SUBJECT);
+            int predicateId = predicate.isVariable() ? 0 : dictionary.getIntID(predicate.asTerm().asNode(), TripleComponentRole.PREDICATE);
+            int objectId = object.isVariable() ? 0 : dictionary.getIntID(object.asTerm().asNode(), TripleComponentRole.OBJECT);
         
             if (subjectId < 0 || predicateId < 0 || objectId < 0) {
                 return createEmptyTriplePatternFragment();
diff --git a/src/org/linkeddatafragments/datasource/index/IndexRequestProcessorForTPFs.java b/src/org/linkeddatafragments/datasource/index/IndexRequestProcessorForTPFs.java
@@ -5,16 +5,18 @@
 import com.hp.hpl.jena.rdf.model.Property;
 import com.hp.hpl.jena.rdf.model.RDFNode;
 import com.hp.hpl.jena.rdf.model.Resource;
+import com.hp.hpl.jena.rdf.model.ResourceFactory;
 import com.hp.hpl.jena.rdf.model.StmtIterator;
 import com.hp.hpl.jena.rdf.model.impl.PropertyImpl;
 import com.hp.hpl.jena.rdf.model.impl.ResourceImpl;
 import java.util.HashMap;
 import java.util.Map;
 
-import org.linkeddatafragments.datasource.AbstractJenaBasedRequestProcessorForTriplePatterns;
+import org.linkeddatafragments.datasource.AbstractRequestProcessorForTriplePatterns;
 import org.linkeddatafragments.datasource.IDataSource;
 import org.linkeddatafragments.datasource.IFragmentRequestProcessor;
 import org.linkeddatafragments.fragments.LinkedDataFragment;
+import org.linkeddatafragments.fragments.tpf.TriplePatternElement;
 import org.linkeddatafragments.fragments.tpf.TriplePatternFragmentRequest;
 
 /**
@@ -26,7 +28,7 @@
  * @author <a href="http://olafhartig.de">Olaf Hartig</a>
  */
 public class IndexRequestProcessorForTPFs
-    extends AbstractJenaBasedRequestProcessorForTriplePatterns
+    extends AbstractRequestProcessorForTriplePatterns<RDFNode,String>
 {
     final static String RDF = "http://www.w3.org/1999/02/22-rdf-syntax-ns#";
     final static String RDFS = "http://www.w3.org/2000/01/rdf-schema#";
@@ -55,27 +57,41 @@ public IndexRequestProcessorForTPFs(
     }
 
     @Override
-    protected Worker getWorker( final TriplePatternFragmentRequest request )
+    protected Worker getTPFSpecificWorker(
+            final TriplePatternFragmentRequest<RDFNode,String> request )
                                                 throws IllegalArgumentException
     {
         return new Worker( request );
     }
 
 
     protected class Worker
-        extends AbstractJenaBasedRequestProcessorForTriplePatterns.Worker
+       extends AbstractRequestProcessorForTriplePatterns.Worker<RDFNode,String>
     {
-        public Worker( final TriplePatternFragmentRequest request ) {
-            super( request );
+        public Worker( final TriplePatternFragmentRequest<RDFNode,String> req )
+        {
+            super( req );
         }
 
         @Override
-        protected LinkedDataFragment createFragment( final Resource subject,
-                                                     final Property predicate,
-                                                     final RDFNode object,
-                                                     final long offset,
-                                                     final long limit )
+        protected LinkedDataFragment createFragment(
+                                  final TriplePatternElement<RDFNode,String> s,
+                                  final TriplePatternElement<RDFNode,String> p,
+                                  final TriplePatternElement<RDFNode,String> o,
+                                  final long offset,
+                                  final long limit )
         {
+            // FIXME: The following algorithm is incorrect for cases in which
+            //        the requested triple pattern contains a specific variable
+            //        multiple times (e.g., ?x foaf:knows ?x ).
+
+            final Resource subject   = s.isVariable() ? null
+                                                      : s.asTerm().asResource();
+            final Property predicate = p.isVariable() ? null
+                                                      : ResourceFactory.createProperty(p.asTerm().asResource().getURI());
+            final RDFNode object     = o.isVariable() ? null
+                                                      : o.asTerm();
+
             StmtIterator listStatements = model.listStatements(subject, predicate, object);
             Model result = ModelFactory.createDefaultModel();
 
diff --git a/src/org/linkeddatafragments/datasource/tdb/JenaTDBBasedRequestProcessorForTPFs.java b/src/org/linkeddatafragments/datasource/tdb/JenaTDBBasedRequestProcessorForTPFs.java
@@ -12,15 +12,14 @@
 import com.hp.hpl.jena.rdf.model.Literal;
 import com.hp.hpl.jena.rdf.model.Model;
 import com.hp.hpl.jena.rdf.model.ModelFactory;
-import com.hp.hpl.jena.rdf.model.Property;
 import com.hp.hpl.jena.rdf.model.RDFNode;
-import com.hp.hpl.jena.rdf.model.Resource;
 import com.hp.hpl.jena.tdb.TDBFactory;
 import java.io.File;
 
-import org.linkeddatafragments.datasource.AbstractJenaBasedRequestProcessorForTriplePatterns;
+import org.linkeddatafragments.datasource.AbstractRequestProcessorForTriplePatterns;
 import org.linkeddatafragments.datasource.IFragmentRequestProcessor;
 import org.linkeddatafragments.fragments.LinkedDataFragment;
+import org.linkeddatafragments.fragments.tpf.TriplePatternElement;
 import org.linkeddatafragments.fragments.tpf.TriplePatternFragmentRequest;
 
 /**
@@ -31,7 +30,7 @@
  * @author <a href="http://olafhartig.de">Olaf Hartig</a>
  */
 public class JenaTDBBasedRequestProcessorForTPFs
-    extends AbstractJenaBasedRequestProcessorForTriplePatterns
+    extends AbstractRequestProcessorForTriplePatterns<RDFNode,String>
 {
     private final Dataset tdb;
     private final String sparql = "CONSTRUCT WHERE { ?s ?p ?o } " +
@@ -43,37 +42,44 @@ public class JenaTDBBasedRequestProcessorForTPFs
     private final Query countQuery = QueryFactory.create(count, Syntax.syntaxSPARQL_11);
 
     @Override
-    protected Worker getWorker( final TriplePatternFragmentRequest request )
+    protected Worker getTPFSpecificWorker(
+            final TriplePatternFragmentRequest<RDFNode,String> request )
                                                 throws IllegalArgumentException
     {
         return new Worker( request );
     }
 
 
     protected class Worker
-        extends AbstractJenaBasedRequestProcessorForTriplePatterns.Worker
+       extends AbstractRequestProcessorForTriplePatterns.Worker<RDFNode,String>
     {
-        public Worker( final TriplePatternFragmentRequest request ) {
-            super( request );
+        public Worker( final TriplePatternFragmentRequest<RDFNode,String> req )
+        {
+            super( req );
         }
 
         @Override
-        protected LinkedDataFragment createFragment( final Resource subject,
-                                                     final Property predicate,
-                                                     final RDFNode object,
-                                                     final long offset,
-                                                     final long limit )
+        protected LinkedDataFragment createFragment(
+                          final TriplePatternElement<RDFNode,String> subject,
+                          final TriplePatternElement<RDFNode,String> predicate,
+                          final TriplePatternElement<RDFNode,String> object,
+                          final long offset,
+                          final long limit )
         {
+            // FIXME: The following algorithm is incorrect for cases in which
+            //        the requested triple pattern contains a specific variable
+            //        multiple times (e.g., ?x foaf:knows ?x ).
+
             Model model = tdb.getDefaultModel();
             QuerySolutionMap map = new QuerySolutionMap();
-            if (subject != null) {
-                map.add("s", subject);
+            if ( ! subject.isVariable() ) {
+                map.add("s", subject.asTerm());
             }
-            if (predicate != null) {
-                map.add("p", predicate);
+            if ( ! predicate.isVariable() ) {
+                map.add("p", predicate.asTerm());
             }
-            if (object != null) {
-                map.add("o", object);
+            if ( ! object.isVariable() ) {
+                map.add("o", object.asTerm());
             }
 
             query.setOffset(offset);
