Extracted an AbstractRegion class with some common functionality of all the region types.

src/main/java/com/sk89q/worldedit/regions/AbstractRegion.java

@@ -0,0 +1,34 @@
+package com.sk89q.worldedit.regions;
+
+import java.util.Iterator;
+
+import com.sk89q.worldedit.BlockVector;
+import com.sk89q.worldedit.LocalWorld;
+
+public abstract class AbstractRegion implements Region {
+    /**
+     * Stores the world.
+     */
+    protected LocalWorld world;
+
+    public AbstractRegion(LocalWorld world) {
+        this.world = world;
+    }
+
+    /**
+     * Get the iterator.
+     *
+     * @return iterator of points inside the region
+     */
+    public Iterator<BlockVector> iterator() {
+        return new RegionIterator(this);
+    }
+
+    public LocalWorld getWorld() {
+        return world;
+    }
+
+    public void setWorld(LocalWorld world) {
+        this.world = world;
+    }
+}

src/main/java/com/sk89q/worldedit/regions/CuboidRegion.java

@@ -32,7 +32,7 @@ import java.util.HashSet;
  *
  * @author sk89q
  */
-public class CuboidRegion implements Region {
+public class CuboidRegion extends AbstractRegion {
     /**
      * Store the first point.
      */
@@ -41,11 +41,6 @@ public class CuboidRegion implements Region {
      * Store the second point.
      */
     private Vector pos2;
-    /**
-     * Stores the world.
-     */
-    private LocalWorld world;
-
     /**
      * Construct a new instance of this cuboid region.
      *
@@ -64,8 +59,8 @@ public class CuboidRegion implements Region {
      * @param pos2
      */
     public CuboidRegion(LocalWorld world, Vector pos1, Vector pos2) {
+        super(world);
         this.pos1 = pos1;
-        this.world = world;
         this.pos2 = pos2;
     }
 
@@ -327,6 +322,7 @@ public class CuboidRegion implements Region {
      *
      * @return iterator of points inside the region
      */
+    @Override
     public Iterator<BlockVector> iterator() {
         return new Iterator<BlockVector>() {
             private Vector min = getMinimumPoint();
@@ -370,12 +366,4 @@ public class CuboidRegion implements Region {
     public String toString() {
         return getMinimumPoint() + " - " + getMaximumPoint();
     }
-
-    public LocalWorld getWorld() {
-        return world;
-    }
-
-    public void setWorld(LocalWorld world) {
-        this.world = world;
-    }
 }

src/main/java/com/sk89q/worldedit/regions/EllipsoidRegion.java

@@ -19,12 +19,10 @@
 
 package com.sk89q.worldedit.regions;
 
-import com.sk89q.worldedit.BlockVector;
 import com.sk89q.worldedit.LocalWorld;
 import com.sk89q.worldedit.Vector;
 import com.sk89q.worldedit.Vector2D;
 import com.sk89q.worldedit.data.ChunkStore;
-import java.util.Iterator;
 import java.util.Set;
 import java.util.HashSet;
 
@@ -32,7 +30,7 @@ import java.util.HashSet;
  *
  * @author TomyLobo
  */
-public class EllipsoidRegion implements Region {
+public class EllipsoidRegion extends AbstractRegion {
     /**
      * Stores the center.
      */
@@ -41,11 +39,6 @@ public class EllipsoidRegion implements Region {
      * Stores the radiuses plus 0.5 on each axis.
      */
     private Vector radius;
-    /**
-     * Stores the world.
-     */
-    private LocalWorld world;
-
     /**
      * Construct a new instance of this ellipsoid region.
      *
@@ -64,7 +57,7 @@ public class EllipsoidRegion implements Region {
      * @param radius
      */
     public EllipsoidRegion(LocalWorld world, Vector center, Vector radius) {
-        this.world = world;
+        super(world);
         this.center = center;
         this.radius = radius;
     }
@@ -211,15 +204,6 @@ public class EllipsoidRegion implements Region {
         return pt.subtract(center).divide(radius).lengthSq() <= 1;
     }
 
-    /**
-     * Get the iterator.
-     *
-     * @return iterator of points inside the region
-     */
-    public Iterator<BlockVector> iterator() {
-        return new RegionIterator(this);
-    }
-
     /**
      * Returns string representation in the format
      * "(centerX, centerY, centerZ) - (radiusX, radiusY, radiusZ)".
@@ -231,14 +215,6 @@ public class EllipsoidRegion implements Region {
         return center + " - " + getRadius();
     }
 
-    public LocalWorld getWorld() {
-        return world;
-    }
-
-    public void setWorld(LocalWorld world) {
-        this.world = world;
-    }
-
     public void extendRadius(Vector minRadius) {
         setRadius(Vector.getMaximum(minRadius, getRadius()));
     }

src/main/java/com/sk89q/worldedit/regions/Polygonal2DRegion.java

@@ -37,14 +37,13 @@ import com.sk89q.worldedit.data.ChunkStore;
  *
  * @author sk89q
  */
-public class Polygonal2DRegion implements Region {
+public class Polygonal2DRegion extends AbstractRegion {
     private List<BlockVector2D> points;
     private BlockVector min;
     private BlockVector max;
     private int minY;
     private int maxY;
     private boolean hasY = false;
-    private LocalWorld world;
 
     /**
      * Construct the region
@@ -72,11 +71,11 @@ public class Polygonal2DRegion implements Region {
      * @param maxY
      */
     public Polygonal2DRegion(LocalWorld world, List<BlockVector2D> points, int minY, int maxY) {
+        super(world);
         this.points = new ArrayList<BlockVector2D>(points);
         this.minY = minY;
         this.maxY = maxY;
         hasY = true;
-        this.world = world;
         recalculate();
     }
 
@@ -440,6 +439,7 @@ public class Polygonal2DRegion implements Region {
      * 
      * @return iterator of points inside the region
      */
+    @Override
     public Iterator<BlockVector> iterator() {
         return new Polygonal2DRegionIterator(this);
 
@@ -603,12 +603,4 @@ public class Polygonal2DRegion implements Region {
             throw new UnsupportedOperationException("Not supported");
         }
     }
-
-    public LocalWorld getWorld() {
-        return world;
-    }
-
-    public void setWorld(LocalWorld world) {
-        this.world = world;
-    }
 }