imported patch JDDVars-merged.patch

prism/src/jdd/JDDVars.java

@@ -152,6 +152,20 @@ public class JDDVars implements Iterable<JDDNode>
 		sortByIndex();
 	}
 
+	/**
+	 * Create a merged JDDVars from the given variables.
+	 * Copies the variables provided as an argument.
+	 * @param ddv the variables
+	 */
+	public static JDDVars merged(JDDVars... ddv) {
+		JDDVars result = new JDDVars();
+		for (JDDVars v : ddv) {
+			result.copyVarsFrom(v);
+		}
+		result.sortByIndex();
+		return result;
+	}
+
 	/**
 	 * Remove variable v from container. Does not decrease the refcount.
 	 */