Rework pref. language logic to act as a filter

epsilonlabs · Dec 18, 2024 · c7ae549 · c7ae549
1 parent 1d512dd
commit c7ae549
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Showing 2 changed files with 68 additions and 26 deletions.
diff --git a/bundles/org.eclipse.epsilon.emc.rdf/src/org/eclipse/epsilon/emc/rdf/RDFResource.java b/bundles/org.eclipse.epsilon.emc.rdf/src/org/eclipse/epsilon/emc/rdf/RDFResource.java
@@ -16,6 +16,7 @@
 import java.util.Collection;
 import java.util.List;
 import java.util.Set;
+import java.util.stream.Collectors;
 
 import org.apache.jena.rdf.model.Literal;
 import org.apache.jena.rdf.model.Property;
@@ -28,12 +29,16 @@
 import org.apache.jena.vocabulary.RDF;
 import org.eclipse.epsilon.eol.execute.context.IEolContext;
 
+import com.google.common.collect.HashMultimap;
 import com.google.common.collect.ListMultimap;
+import com.google.common.collect.Multimap;
 import com.google.common.collect.MultimapBuilder;
 
 public class RDFResource extends RDFModelElement {
 	protected static final String LITERAL_SUFFIX = "_literal";
-	protected static List<String> preferredLanguageTagList;
+
+	// TODO should be moved to the model, and parsed only once when the model loads
+	protected List<String> preferredLanguageTagList;
 
 	enum LiteralMode {
 		RAW, VALUES_ONLY
@@ -51,45 +56,82 @@ public RDFResource(Resource resource, RDFModel rdfModel) {
 	public Resource getResource() {
 		return resource;
 	}
-
-
-	private Collection<Object> getPropertyPreferredLanguage(RDFQualifiedName pName, IEolContext context, LiteralMode literalMode) {
-		Collection<Object> value = null ;
-		for (String lTag : preferredLanguageTagList) {
-			RDFQualifiedName withLanguageTag = pName.withLanguageTag(lTag);
-			value = getProperty(withLanguageTag, context, literalMode);
-			if (!value.isEmpty()) {
-				break;
-			}
-		}
-		return value;
-	}
 
 	public Collection<Object> getProperty(String property, IEolContext context) {
 		final RDFQualifiedName pName = RDFQualifiedName.from(property, this.owningModel::getNamespaceURI);
-		Collection<Object> value = null ;
-
-		if ((pName.languageTag != null) && (pName.languageTag.equals(""))) { // Try preferred language tags
-			value = getPropertyPreferredLanguage(pName, context, LiteralMode.VALUES_ONLY);
-		} else { // A language tag was provided
-			value = getProperty(pName, context, LiteralMode.VALUES_ONLY);
+
+		Collection<Object> value = getProperty(pName, context, LiteralMode.RAW);
+		if (!value.isEmpty() && !value.stream().anyMatch(p -> p instanceof RDFResource)) {
+			value = filterByPreferredLanguage(value, LiteralMode.VALUES_ONLY);
+			if (!value.isEmpty()) {
+				return value;
+			}
 		}
 
 		if (value.isEmpty() && pName.localName.endsWith(LITERAL_SUFFIX)) {
 			final String localNameWithoutSuffix = pName.localName.substring(0,
 					pName.localName.length() - LITERAL_SUFFIX.length());
 			RDFQualifiedName withoutLiteral = pName.withLocalName(localNameWithoutSuffix);
 
-			if ((pName.languageTag != null) && (pName.languageTag.equals(""))) { // Try preferred language tags
-				return getPropertyPreferredLanguage(withoutLiteral, context, LiteralMode.RAW);
-			} else { // A tag was provided
-				return getProperty(withoutLiteral, context, LiteralMode.RAW);
+			value = getProperty(withoutLiteral, context, LiteralMode.RAW);
+			if (!value.isEmpty() && !value.stream().anyMatch(p -> p instanceof RDFResource)) {
+				value = filterByPreferredLanguage(value, LiteralMode.RAW);
 			}
 		}
 
 		return value;
+	}
 
+	private Collection<Object> filterByPreferredLanguage(Collection<Object> value, LiteralMode literalMode) {
+		// If no preferred languages are specified, don't do any filtering
+		if (preferredLanguageTagList.isEmpty()) {
+			switch (literalMode) {
+			case RAW:
+				return value;
+			case VALUES_ONLY:
+				return value.stream().map(e -> e instanceof RDFLiteral
+					? ((RDFLiteral) e).getValue() : e).collect(Collectors.toList());
+			default:
+				throw new IllegalArgumentException("Unknown literal mode " + literalMode);
+			}
+		}
+
+		// Otherwise, group literals by language tag
+		Multimap<String, RDFLiteral> literalsByTag = HashMultimap.create();
+		for (Object element : value) {
+			if (element instanceof RDFLiteral) {
+				RDFLiteral literal = (RDFLiteral) element;
+				literalsByTag.put(literal.getLanguage() == null ? "" : literal.getLanguage(), literal);
+			} else {
+				// TODO see if we run into this scenario, print some warning, return value as is as fallback
+				throw new IllegalArgumentException("Expected RDFLiteral while filtering based on preferred languages, but got " + element);
+			}
+		}
+
+		for (String tag : preferredLanguageTagList) {
+			if (literalsByTag.containsKey(tag)) {
+				switch (literalMode) {
+				case RAW:
+					return new ArrayList<>(literalsByTag.get(tag));
+				case VALUES_ONLY:
+					return literalsByTag.get(tag).stream().map(l -> 
+					l.getValue()).collect(Collectors.toList());
+				}
+			}
+		}
 
+		// If we don't find any matches in the preferred languages,
+		// fall back to the untagged literals (if any).
+		Collection<RDFLiteral> rawFromUntagged = literalsByTag.get("");
+		switch (literalMode) {
+		case RAW:
+			return new ArrayList<>(rawFromUntagged);
+		case VALUES_ONLY:
+			return rawFromUntagged.stream().map(l -> l.getValue())
+				.collect(Collectors.toList());
+		default:
+			throw new IllegalArgumentException("Unknown literal mode " + literalMode);
+		}
 	}
 
 	public Collection<Object> getProperty(RDFQualifiedName pName, IEolContext context, LiteralMode literalMode) {

diff --git a/examples/org.eclipse.epsilon.examples.emc.rdf.turtles/example.eol b/examples/org.eclipse.epsilon.examples.emc.rdf.turtles/example.eol
@@ -8,8 +8,8 @@ goblin.enemyOf.println('Enemies of Green Goblin (without prefix): ');
 //
 // Q. Do we want some setting of "preferred language" for the RDF driver, instead of showing values for all languages?
 
-goblin.enemyOf.name.flatten.println('All names of the enemies of the Green Goblin: ');
-goblin.enemyOf.`name@`.flatten.println('All names in the default language of the enemies of the Green Goblin: ');
+goblin.enemyOf.name.flatten.println('All names of the enemies of the Green Goblin (using language preferences, if any): ');
+goblin.enemyOf.`name@`.flatten.println('All names without a language tag of the enemies of the Green Goblin: ');
 goblin.enemyOf.`name@ru`.flatten.println('All Russian names of the enemies of the Green Goblin: ');
 goblin.enemyOf.name_literal.flatten.println('All name literals of the enemies of the Green Goblin: ');
 goblin.enemyOf.`name_literal@`.flatten.println('All name literals in the default language of the enemies of the Green Goblin: ');