Added initial VocabUtil code

Signed-off-by:Bart Hanssens <bart.hanssens@fedict.be>

Author: barthanssens

core/model/src/main/java/org/eclipse/rdf4j/model/util/VocabUtil.java

@@ -0,0 +1,44 @@
+/**
+ * Copyright (c) 2017 Eclipse RDF4J contributors, and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Distribution License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/org/documents/edl-v10.php.
+ */
+package org.eclipse.rdf4j.model.util;
+
+import java.lang.reflect.Field;
+import java.lang.reflect.Modifier;
+import java.util.HashSet;
+import java.util.Set;
+
+import org.eclipse.rdf4j.model.IRI;
+
+/**
+ * Utility functions for working with vocabularies.
+ * 
+ * @author Bart Hanssens
+ */
+public class VocabUtil {
+    
+    /**
+     * Get all the {@link IRI IRIs} of the classes and properties of a vocabulary.
+     *  
+     * @param vocabulary RDF vocabulary
+     * @return set of IRIs
+     */
+    public static Set<IRI> getVocabularyIRIs(Class vocabulary) {
+        Set<IRI> iris = new HashSet<>();
+        
+        for(Field f : vocabulary.getFields ()) {
+            if (f.getType().equals(IRI.class) && Modifier.isPublic(f.getModifiers())) {
+                try {
+                    iris.add((IRI) f.get(f));
+                } catch (IllegalArgumentException|IllegalAccessException ex) {
+                   // should not happen
+                }
+            }
+        }
+        return iris;
+    }
+}