add type information to the interface

src/difflib/ChangeDelta.java

@@ -84,4 +84,9 @@ public class ChangeDelta extends Delta {
         return "[ChangeDelta, position: " + getOriginal().getPosition() + ", lines: "
                 + getOriginal().getLines() + " to " + getRevised().getLines() + "]";
     }
+
+    @Override
+    public TYPE getType() {
+        return Delta.TYPE.CHANGE;
+    }
 }

src/difflib/DeleteDelta.java

@@ -58,6 +58,11 @@ public class DeleteDelta extends Delta {
         }
     }
     
+    @Override
+    public TYPE getType() {
+        return Delta.TYPE.DELETE;
+    }
+    
     @Override
     public void verify(List<?> target) throws PatchFailedException {
         getOriginal().verify(target);

src/difflib/Delta.java

@@ -26,6 +26,10 @@ public abstract class Delta {
     private Chunk original;
     private Chunk revised;
     
+    public enum TYPE {
+        CHANGE, DELETE, INSERT
+    }
+    
     /**
      * Construct the delta for original and revised chunks
      * 
@@ -61,6 +65,12 @@ public abstract class Delta {
      */
     public abstract void restore(List<Object> target);
     
+    /**
+     * Returns the type of delta
+     * @return the type enum
+     */
+    public abstract TYPE getType();
+    
     /**
      * @return the Chunk describing the original text
      */

src/difflib/InsertDelta.java

@@ -66,6 +66,10 @@ public class InsertDelta extends Delta {
         
     }
     
+    public TYPE getType() {
+        return Delta.TYPE.INSERT;
+    }
+    
     @Override
     public String toString() {
         return "[InsertDelta, position: " + getOriginal().getPosition() + ", lines: "