GH-4921 Turtle writer does not respect namespaces in IRIs

- Fix RDFXML test by checking if a localname preference indicated by the IRI is valid in XML - if not, try to find an alternative representation

Author: reckart

core/model/src/main/java/org/eclipse/rdf4j/model/impl/SimpleIRI.java

@@ -79,7 +79,7 @@ protected void setIRIString(String namespace, String localname) {
 		Objects.requireNonNull(namespace, "namespace must not be null");
 		Objects.requireNonNull(localname, "localname must not be null");
 
-		String joinedIriString = namespace + localname;
+		var joinedIriString = namespace + localname;
 
 		if (joinedIriString.indexOf(':') < 0) {
 			throw new IllegalArgumentException("Not a valid (absolute) IRI: " + joinedIriString);

core/rio/rdfxml/src/main/java/org/eclipse/rdf4j/rio/rdfxml/RDFXMLWriter.java

@@ -106,6 +106,7 @@ public Writer getWriter() {
 		return writer;
 	}
 
+	@Override
 	public Collection<RioSetting<?>> getSupportedSettings() {
 		final Collection<RioSetting<?>> settings = new HashSet<>(super.getSupportedSettings());
 		settings.add(BasicWriterSettings.BASE_DIRECTIVE);

core/rio/rdfxml/src/main/java/org/eclipse/rdf4j/rio/rdfxml/util/RDFXMLPrettyWriter.java

@@ -18,8 +18,10 @@
 import java.util.Collection;
 import java.util.HashSet;
 import java.util.Stack;
+import java.util.regex.Pattern;
 
 import org.eclipse.rdf4j.common.net.ParsedIRI;
+import org.eclipse.rdf4j.common.xml.XMLUtil;
 import org.eclipse.rdf4j.model.BNode;
 import org.eclipse.rdf4j.model.IRI;
 import org.eclipse.rdf4j.model.Literal;
@@ -260,8 +262,9 @@ private void popStacks(Resource newSubject) throws IOException, RDFHandlerExcept
 					writeIndents(i * 2 - 1);
 
 					IRI predicate = predicateStack.get(i - 1);
+					var predicateQName = new QName(predicate);
 
-					writeStartTag(predicate.getNamespace(), predicate.getLocalName());
+					writeStartTag(predicateQName.getNamespace(), predicateQName.getLocalName());
 					writeNewLine();
 				}
 
@@ -281,6 +284,7 @@ private void popStacks(Resource newSubject) throws IOException, RDFHandlerExcept
 			writeNewLine();
 		} else {
 			IRI topPredicate = predicateStack.pop();
+			var topPredicateQName = new QName(topPredicate);
 
 			if (!topNode.hasType()) {
 				// we can use an abbreviated predicate
@@ -291,7 +295,7 @@ private void popStacks(Resource newSubject) throws IOException, RDFHandlerExcept
 				// written out as well
 
 				writeIndents(nodeStack.size() * 2 - 1);
-				writeStartTag(topPredicate.getNamespace(), topPredicate.getLocalName());
+				writeStartTag(topPredicateQName.getNamespace(), topPredicateQName.getLocalName());
 				writeNewLine();
 
 				// write out an empty subject
@@ -300,7 +304,7 @@ private void popStacks(Resource newSubject) throws IOException, RDFHandlerExcept
 				writeNewLine();
 
 				writeIndents(nodeStack.size() * 2 - 1);
-				writeEndTag(topPredicate.getNamespace(), topPredicate.getLocalName());
+				writeEndTag(topPredicateQName.getNamespace(), topPredicateQName.getLocalName());
 				writeNewLine();
 			}
 		}
@@ -322,10 +326,11 @@ private void popStacks(Resource newSubject) throws IOException, RDFHandlerExcept
 
 				if (predicateStack.size() > 0) {
 					IRI nextPredicate = predicateStack.pop();
+					var nextPredicateQName = new QName(nextPredicate);
 
 					writeIndents(predicateStack.size() + nodeStack.size());
 
-					writeEndTag(nextPredicate.getNamespace(), nextPredicate.getLocalName());
+					writeEndTag(nextPredicateQName.getNamespace(), nextPredicateQName.getLocalName());
 
 					writeNewLine();
 				}
@@ -392,7 +397,8 @@ private void writeNodeStartOfStartTag(Node node) throws IOException, RDFHandlerE
 
 		if (node.hasType()) {
 			// We can use abbreviated syntax
-			writeStartOfStartTag(node.getType().getNamespace(), node.getType().getLocalName());
+			var nodeTypeQName = new QName(node.getType());
+			writeStartOfStartTag(nodeTypeQName.getNamespace(), nodeTypeQName.getLocalName());
 		} else {
 			// We cannot use abbreviated syntax
 			writeStartOfStartTag(RDF.NAMESPACE, "Description");
@@ -423,7 +429,8 @@ private void writeNodeStartTag(Node node) throws IOException, RDFHandlerExceptio
 	 */
 	private void writeNodeEndTag(Node node) throws IOException {
 		if (node.getType() != null) {
-			writeEndTag(node.getType().getNamespace(), node.getType().getLocalName());
+			var nodeTypeQName = new QName(node.getType());
+			writeEndTag(nodeTypeQName.getNamespace(), nodeTypeQName.getLocalName());
 		} else {
 			writeEndTag(RDF.NAMESPACE, "Description");
 		}
@@ -442,7 +449,8 @@ private void writeNodeEmptyTag(Node node) throws IOException, RDFHandlerExceptio
 	 * Write out an empty property element.
 	 */
 	private void writeAbbreviatedPredicate(IRI pred, Value obj) throws IOException, RDFHandlerException {
-		writeStartOfStartTag(pred.getNamespace(), pred.getLocalName());
+		var predQName = new QName(pred);
+		writeStartOfStartTag(predQName.getNamespace(), predQName.getLocalName());
 
 		if (obj instanceof Resource) {
 			Resource objRes = (Resource) obj;
@@ -484,7 +492,7 @@ private void writeAbbreviatedPredicate(IRI pred, Value obj) throws IOException,
 				writeCharacterData(objLit.getLabel());
 			}
 
-			writeEndTag(pred.getNamespace(), pred.getLocalName());
+			writeEndTag(predQName.getNamespace(), predQName.getLocalName());
 		}
 
 		writeNewLine();
@@ -565,4 +573,31 @@ public boolean isWritten() {
 			return isWritten;
 		}
 	}
+
+	private static class QName {
+		private static final Pattern VALID_XML_ELEMENT_NAME = Pattern.compile("[a-zA-Z_][a-zA-Z0-9_\\-\\.]*");
+
+		private final String namespace;
+		private final String localName;
+
+		public QName(IRI resource) {
+			if (!VALID_XML_ELEMENT_NAME.matcher(resource.getLocalName()).matches()) {
+				var iriString = resource.getNamespace() + resource.getLocalName();
+				var sep = XMLUtil.findURISplitIndex(iriString);
+				namespace = iriString.substring(0, sep);
+				localName = iriString.substring(sep);
+			} else {
+				localName = resource.getLocalName();
+				namespace = resource.getNamespace();
+			}
+		}
+
+		public String getLocalName() {
+			return localName;
+		}
+
+		public String getNamespace() {
+			return namespace;
+		}
+	}
 }