Github user afs commented on a diff in the pull request:
https://github.com/apache/jena/pull/94#discussion_r44027943
--- Diff:
jena-arq/src/main/java/org/apache/jena/sparql/core/assembler/InMemDatasetAssembler.java
---
@@ -0,0 +1,67 @@
+package org.apache.jena.sparql.core.assembler;
+
+import static org.apache.jena.assembler.JA.MemoryDataset;
+import static org.apache.jena.assembler.JA.data;
+import static org.apache.jena.query.DatasetFactory.createTxnMem;
+import static org.apache.jena.riot.RDFDataMgr.loadModel;
+import static org.apache.jena.riot.RDFDataMgr.read;
+import static
org.apache.jena.sparql.core.assembler.AssemblerUtils.setContext;
+import static
org.apache.jena.sparql.core.assembler.DatasetAssemblerVocab.*;
+import static org.apache.jena.sparql.util.FmtUtils.stringForRDFNode;
+import static org.apache.jena.sparql.util.graph.GraphUtils.*;
+
+import java.util.function.Predicate;
+
+import org.apache.jena.assembler.Assembler;
+import org.apache.jena.assembler.Mode;
+import org.apache.jena.assembler.assemblers.AssemblerBase;
+import org.apache.jena.query.Dataset;
+import org.apache.jena.rdf.model.Model;
+import org.apache.jena.rdf.model.RDFNode;
+import org.apache.jena.rdf.model.Resource;
+
+/**
+ * An {@link Assembler} that creates in-memory {@link Dataset}s.
+ *
+ */
+public class InMemDatasetAssembler extends AssemblerBase {
+
+ @Override
+ public Dataset open(final Assembler assembler, final Resource root,
final Mode mode) {
+ checkType(root, MemoryDataset);
+ final Dataset dataset = createTxnMem();
+ setContext(root, dataset.getContext());
+ // Default graph can be defined with ja:graph or ja:defaultGraph
+ final Resource defaultGraphDef =
root.hasProperty(pDefaultGraph) ? getResourceValue(root,
+ pDefaultGraph) : root.hasProperty(pGraph) ?
getResourceValue(root, pGraph) : null;
--- End diff --
They are different. `ja:defaultGraph` leads to a full model description.
Assembling it builds the model in memory and then takes a copy.
`ja:graph` reads a file into a graph. Not general, not a copy. It's needed
too put a triples file into a named graph.
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