Print default graph quads as triples if output is a triples syntax.

jena-arq/src/main/java/org/apache/jena/riot/out/NodeFmtLib.java

@@ -164,6 +164,12 @@ public static String displayStr(Triple t) {
         return displayStrNodes(t.getSubject(), t.getPredicate(), t.getObject());
     }
 
+    public static String displayStr(Quad q) {
+        if ( q == null )
+            return nullStr;
+        return displayStrNodes(q.getGraph(), q.getSubject(), q.getPredicate(), q.getObject());
+    }
+
     public static String displayStr(Node node) {
         if ( node == null )
             return nullStr;

jena-arq/src/main/java/org/apache/jena/riot/system/StreamRDFWrapper.java

@@ -28,9 +28,10 @@
 public class StreamRDFWrapper implements StreamRDF
 {
     protected final StreamRDF other ;
+    public final StreamRDF get() { return other; }
 
     public StreamRDFWrapper(StreamRDF other) { this.other = other ; }
-    
+
     @Override
     public void start()
     { other.start() ; }

jena-arq/src/main/java/org/apache/jena/riot/system/StreamRDFWriter.java

@@ -225,9 +225,19 @@ public static StreamRDF getWriterStream(OutputStream output, RDFFormat format, C
         if ( context == null )
             context = RIOT.getContext().copy();
         StreamRDF stream = x.create(output, format, context);
+        if ( ! RDFLanguages.isQuads(format.getLang()) )
+            stream = triplesOnly(stream);
         return stream ;
     }
 
+
+    /* What to do if a quad is seen when writing in a triples-only syntax. */
+    private static StreamRDF triplesOnly(StreamRDF stream) {
+        // StreamTriplesOnly converts default graph quads to triples.
+        // Otherwise, throw exception.
+        return StreamTriplesOnly.exceptionOnQuads(stream);
+    }
+
     public static boolean registered(Lang lang) {
         RDFFormat fmt = registry.defaultSerialization(lang) ;
         return registry.contains(fmt) ;

jena-arq/src/main/java/org/apache/jena/riot/system/StreamTriplesOnly.java

@@ -18,6 +18,10 @@
 
 package org.apache.jena.riot.system;
 
+import java.util.function.Function;
+
+import org.apache.jena.riot.RiotException;
+import org.apache.jena.riot.out.NodeFmtLib;
 import org.apache.jena.sparql.core.Quad;
 
 /**
@@ -27,27 +31,51 @@
  */
 public class StreamTriplesOnly extends StreamRDFWrapper {
 
-    public static StreamRDF actionIfQuads(StreamRDF stream, Runnable action) {
+    public static enum QuadPolicy { CALL, IGNORE }
+
+    /** Exception on non-delfault graph quad */
+    private static Function<Quad, QuadPolicy> actionException = (q) -> {
+        throw new RiotException("Quad in Triple output: "+NodeFmtLib.str(q));
+    };
+
+    /** Replace an existing wrapper with a new policy for quads */
+    public static StreamRDF setActionIfQuads(StreamRDF stream, Function<Quad, QuadPolicy> action) {
+        // Strip existing layers.
+        while ( stream instanceof StreamTriplesOnly stream2 ) {
+            stream = stream2.get();
+        }
+        return addActionIfQuads(stream, action);
+    }
+
+    /** Add a new policy layer for quads */
+    public static StreamRDF addActionIfQuads(StreamRDF stream, Function<Quad, QuadPolicy> action) {
         return new StreamTriplesOnly(stream, action);
     }
 
-    private boolean seenQuads = false;
-    private final Runnable action;
+    /** Throw a {@link RiotException} if a non-default graph quad is seen. */
+    public static StreamRDF exceptionOnQuads(StreamRDF stream) {
+        return new StreamTriplesOnly(stream, actionException);
+    }
+
+    private QuadPolicy quadAction = QuadPolicy.CALL;
+    // The policy when seeing a quad that isn't in the default graph.
+    // Return true for "continue calling"
+    // Return false for "don't call again, ignore from now on"
+    private final Function<Quad, QuadPolicy> action;
 
-    private StreamTriplesOnly(StreamRDF sink, Runnable action) {
+    private StreamTriplesOnly(StreamRDF sink, Function<Quad, QuadPolicy> action) {
         super(sink) ;
         this.action = action;
     }
 
     @Override
     public void quad(Quad quad) {
-        if ( quad.isTriple() || quad.isDefaultGraph() || quad.isUnionGraph() ) {
+        if ( quad.getGraph() == null || quad.isTriple() || quad.isDefaultGraph() ) {
             triple(quad.asTriple()) ;
             return;
         }
-        if ( ! seenQuads ) {
-            action.run();
-            seenQuads = true;
+        if ( quadAction == QuadPolicy.CALL ) {
+            quadAction = action.apply(quad);
         }
     }
 

jena-arq/src/main/java/org/apache/jena/riot/writer/WriterStreamRDFBase.java

@@ -47,7 +47,6 @@
  * <p>
  * For N-Quads and N-triples use {@link WriterStreamRDFPlain}.
  */
-
 public abstract class WriterStreamRDFBase implements StreamRDF
 {
     // What did we do last?

jena-cmds/src/main/java/riotcmd/CmdLangParse.java

@@ -23,6 +23,7 @@
 import java.io.OutputStream;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.function.Function;
 import java.util.zip.GZIPOutputStream;
 
 import arq.cmdline.ModContext;
@@ -82,12 +83,12 @@ protected String getSummary() {
     }
 
     protected List<ParseRecord> outcomes = new ArrayList<>();
-
     protected OutputStream outputWrite = System.out;
     protected StreamRDF parserOutputStream = null;
     protected String parserBaseIRI = null;
     protected boolean passRelativeURIs = false;
     protected String writerBaseIRI = null;
+
     @Override
     protected void processModulesAndArgs() {
         cmdStrictMode = super.contains(argStrict);
@@ -202,18 +203,18 @@ protected void exec() {
 
         if ( ! modLangParse.mergeQuads() && ! isQuadsOutput() ) {
             // Only pass through triples.
-            final StreamRDF dest = parserOutputStream;
             if ( isStreamingOutput() ) {
-                Runnable action = () -> {
+                Function<Quad, StreamTriplesOnly.QuadPolicy> action = (quad) -> {
                     // dest may be significantly buffered over the top of the output stream.
                     // The log message does not necessarily come out in the right place - it may be early.
+                    // "Best effort" attempt to align log message to output.
                     IO.flush(outputWrite);
                     Log.warn(SysRIOT.getLogger(), "Quads in triples output - quads ignored.");
+                    return StreamTriplesOnly.QuadPolicy.IGNORE;
                 };
-                parserOutputStream = StreamTriplesOnly.actionIfQuads(parserOutputStream, action);
-            } else {
-                // Not streaming - code can issue error before formatting.
+                parserOutputStream = StreamTriplesOnly.setActionIfQuads(parserOutputStream, action);
             }
+            // If not streaming, leave to the writer,
         }
 
         // If QuadsToTriples is added here, then counts will be "triples only"

jena-extras/jena-querybuilder/src/main/java/org/apache/jena/arq/querybuilder/AbstractQueryBuilder.java

@@ -85,7 +85,7 @@ public Node makeNode(Object o) {
 
     /**
      * Make a node or path from the object using the query prefix mapping.
-     * 
+     *
      * @param o the object to make the node or path from.
      * @return A node or path.
      * @see Converters#makeNodeOrPath(Object, PrefixMapping)
@@ -108,7 +108,7 @@ private Object makeNodeOrPath(Object o) {
      * <li>Will create a literal representation if the parseNode() fails or for any
      * other object type.</li>
      * </ul>
-     * 
+     *
      * @param o the object that should be interpreted as a path or a node.
      * @param pMapping the prefix mapping to resolve path or node with
      * @return the Path or Node
@@ -146,7 +146,7 @@ public ElementSubQuery asSubQuery() {
      * @param p the predicate object
      * @param o the object object.
      * @return a TriplePath
-     * @deprecated Use {@link makeTriplePaths(Object, Object, Object)}
+     * @deprecated Use {@link #makeTriplePaths(Object, Object, Object)}
      */
     @Deprecated(since="5.0.0")
     public TriplePath makeTriplePath(Object s, Object p, Object o) {
@@ -156,7 +156,7 @@ public TriplePath makeTriplePath(Object s, Object p, Object o) {
         }
         return new TriplePath(Triple.create(makeNode(s), (Node) po, makeNode(o)));
     }
-    
+
     /**
      * Make a collecton triple path from the objects.
      *
@@ -166,7 +166,7 @@ public TriplePath makeTriplePath(Object s, Object p, Object o) {
      * <li>Will return the enclosed Node from a FrontsNode</li>
      * <li>Will return the object if it is a Node.</li>
      * <li>For {@code subject} and {@code object} <em>only</em>, if the object is a collection, will convert each item
-     * in the collection into a node and create an RDF list. All RDF list nodes are included in the collection.</li> 
+     * in the collection into a node and create an RDF list. All RDF list nodes are included in the collection.</li>
      * <li>If the object is a String
      * <ul>
      * <li>For <code>predicate</code> <em>only</em>, will attempt to parse as a path</li>
@@ -201,7 +201,7 @@ public Expr makeExpr(String expression) throws QueryParseException {
 
     /**
      * A convenience method to quote a string.
-     * 
+     *
      * @param q the string to quote.
      *
      * Will use single quotes if there are no single quotes in the string or if the
@@ -219,7 +219,7 @@ public static String quote(String q) {
 
     /**
      * Verify that any Node_Variable nodes are returned as Var nodes.
-     * 
+     *
      * @param n the node to check
      * @return the node n or a new Var if n is an instance of Node_Variable
      * @deprecated use {@link Converters#checkVar(Node)}
@@ -240,7 +240,7 @@ public static Node checkVar(Node n) {
      * <li>Will create a literal representation if the parseNode() fails or for any
      * other object type.</li>
      * </ul>
-     * 
+     *
      * @param o The object to convert (may be null).
      * @param pMapping The prefix mapping to use for prefix resolution.
      * @return The Node value.
@@ -287,7 +287,7 @@ protected AbstractQueryBuilder() {
 
     /**
      * Get the HandlerBlock for this query builder.
-     * 
+     *
      * @return The associated handler block.
      */
     public abstract HandlerBlock getHandlerBlock();
@@ -304,7 +304,7 @@ public ValuesHandler getValuesHandler() {
 
     /**
      * Gets the where handler used by this QueryBuilder.
-     * 
+     *
      * @return the where handler used by this QueryBuilder.
      */
     public final WhereHandler getWhereHandler() {
@@ -313,7 +313,7 @@ public final WhereHandler getWhereHandler() {
 
     /**
      * Adds the contents of the whereClause to the where clause of this builder.
-     * 
+     *
      * @param whereClause the where clause to add.
      * @return this builder for chaining.
      */
@@ -410,7 +410,7 @@ public T setBase(Object base) {
 
     /**
      * Creates a collection of nodes from an iterator of Objects.
-     * 
+     *
      * @param iter the iterator of objects, may be null or empty.
      * @param prefixMapping the PrefixMapping to use when nodes are created.
      * @return a Collection of nodes or null if iter is null or empty.
@@ -424,7 +424,7 @@ public static Collection<Node> makeValueNodes(Iterator<?> iter, PrefixMapping pr
     /**
      * Creates a collection of nodes from an iterator of Objects. Uses the prefix
      * mapping from the PrologHandler.
-     * 
+     *
      * @param iter the iterator of objects, may be null or empty.
      * @return a Collection of nodes or null if iter is null or empty.
      */

jena-extras/jena-serviceenhancer/src/test/java/org/apache/jena/sparql/service/enhancer/impl/TestServiceEnhancerMisc.java

@@ -503,7 +503,7 @@ public void testBulkRequestsOverCachedEmptyResultSets() {
             "   SERVICE <loop:cache:bulk+5> { ?s rdfs:label ?l }",
             "}");
 
-        Dataset ds = RDFParser.fromString(dataStr).lang(Lang.TURTLE).toDataset();
+        Dataset ds = RDFParser.fromString(dataStr, Lang.TURTLE).toDataset();
         Query query = QueryFactory.create(queryStr);
 
         int rsSize;