Small extra stuffs. PS.getDistinctChunks and reverseIndex of map.

src/main/java/com/massivecraft/massivecore/ps/PS.java

@@ -1,6 +1,9 @@
 package com.massivecraft.massivecore.ps;
 
 import java.io.Serializable;
+import java.util.Collection;
+import java.util.LinkedHashSet;
+import java.util.Set;
 import java.util.Map.Entry;
 
 import org.bukkit.Bukkit;
@@ -839,6 +842,20 @@ public final class PS implements Cloneable, Serializable, Comparable<PS>
 		return inSameUniverse(one, two, aspect.getMultiverse());
 	}
 	
+	// -------------------------------------------- //
+	// GET SETS
+	// -------------------------------------------- //
+	
+	public static Set<PS> getDistinctChunks(Collection<PS> pss)
+	{
+		Set<PS> ret = new LinkedHashSet<PS>();
+		for (PS ps : pss)
+		{
+			ret.add(ps.getChunk(true));
+		}
+		return ret;
+	}
+	
 	// -------------------------------------------- //
 	// HASHCODE (CACHED)
 	// -------------------------------------------- //

src/main/java/com/massivecraft/massivecore/util/MUtil.java

@@ -653,6 +653,27 @@ public class MUtil
 		return ret;
 	}
 	
+	public static <K, V> Map<V, Set<K>> reverseIndex(Map<K, V> map)
+	{
+		Map<V, Set<K>> ret = new LinkedHashMap<V, Set<K>>();
+		
+		for (Entry<K, V> entry : map.entrySet())
+		{
+			K key = entry.getKey();
+			V value = entry.getValue();
+			
+			Set<K> set = ret.get(value);
+			if (set == null)
+			{
+				set = new HashSet<K>();
+				ret.put(value, set);
+			}
+			set.add(key);
+		}
+		
+		return ret;
+	}
+	
 	// -------------------------------------------- //
 	// COLLECTION MANIPULATION
 	// -------------------------------------------- //