Refactor the StaticValidator to reuse code in DependencyGraphs.

src/org/ggp/base/util/gdl/model/DependencyGraphs.java

@@ -19,40 +19,66 @@
 import com.google.common.collect.SetMultimap;
 import com.google.common.collect.Sets;
 
+/**
+ * When dealing with GDL, dependency graphs are often useful. DependencyGraphs
+ * offers a variety of functionality for dealing with dependency graphs expressed
+ * in the form of SetMultimaps.
+ *
+ * These multimaps are paired with sets of all nodes, to account for the
+ * possibility of nodes not included in the multimap representation.
+ *
+ * All methods assume that keys in multimaps depend on their associated values,
+ * or in other words are downstream of or are children of those values.
+ */
 public class DependencyGraphs {
 	private DependencyGraphs() {}
 
 	/**
 	 * Returns all elements of the dependency graph that match the
-	 * given predicate, and any elements downstream of those matching
+	 * given predicate, and any elements upstream of those matching
 	 * elements.
 	 *
 	 * The graph may contain cycles.
 	 *
 	 * Each key in the dependency graph depends on/is downstream of
 	 * its associated values.
 	 */
-	public static <T> ImmutableSet<T> getMatchingAndDownstream(
+	public static <T> ImmutableSet<T> getMatchingAndUpstream(
 			Set<T> allNodes,
 			SetMultimap<T, T> dependencyGraph,
 			Predicate<T> matcher) {
 		Set<T> results = Sets.newHashSet();
 
-		SetMultimap<T, T> reversedGraph = reverseGraph(dependencyGraph);
-
 		Deque<T> toTry = Queues.newArrayDeque();
 		toTry.addAll(Collections2.filter(allNodes, matcher));
 
 		while (!toTry.isEmpty()) {
 			T curElem = toTry.remove();
 			if (!results.contains(curElem)) {
 				results.add(curElem);
-				toTry.addAll(reversedGraph.get(curElem));
+				toTry.addAll(dependencyGraph.get(curElem));
 			}
 		}
 		return ImmutableSet.copyOf(results);
 	}
 
+	/**
+	 * Returns all elements of the dependency graph that match the
+	 * given predicate, and any elements downstream of those matching
+	 * elements.
+	 *
+	 * The graph may contain cycles.
+	 *
+	 * Each key in the dependency graph depends on/is downstream of
+	 * its associated values.
+	 */
+	public static <T> ImmutableSet<T> getMatchingAndDownstream(
+			Set<T> allNodes,
+			SetMultimap<T, T> dependencyGraph,
+			Predicate<T> matcher) {
+		return getMatchingAndUpstream(allNodes, reverseGraph(dependencyGraph), matcher);
+	}
+
 	public static <T> SetMultimap<T, T> reverseGraph(SetMultimap<T, T> graph) {
 		return Multimaps.invertFrom(graph, HashMultimap.<T, T>create());
 	}