AbstractCollection's isEmpty() calls size(). We can often do better:

- Provide an implementation in AbstractIntSet that checks the interator
  for at least one element.
- Override that in ArrayIntSet so that we're just checking our size again.
- Added optimized isEmpty()s for a few of the inner classes in IntSets.


git-svn-id: https://samskivert.googlecode.com/svn/trunk@2701 6335cc39-0255-0410-8fd6-9bcaacd3b74c

src/java/com/samskivert/util/AbstractIntSet.java

@@ -71,6 +71,18 @@ public abstract class AbstractIntSet extends AbstractSet<Integer>
         return size;
     }
 
+    /**
+     * {@inheritDoc}
+     *
+     * <p>This implementation simply checks to see if the interator has a first element.
+     */
+    @Override
+    public boolean isEmpty ()
+    {
+        // possibly dumb implementation. Override if you can do better.
+        return !interator().hasNext();
+    }
+
     // from IntSet
     public boolean add (int value)
     {

src/java/com/samskivert/util/ArrayIntSet.java

@@ -268,12 +268,18 @@ public class ArrayIntSet extends AbstractIntSet
         return values;
     }
 
-    @Override // from AbstractSet<Integer>
+    @Override // from AbstractCollection<Integer>
     public int size ()
     {
         return _size;
     }
 
+    @Override // from AbstractCollection<Integer>
+    public boolean isEmpty ()
+    {
+        return (_size == 0);
+    }
+
     @Override // from AbstractIntSet
     public boolean retainAll (Collection<?> c)
     {

src/java/com/samskivert/util/IntSets.java

@@ -210,6 +210,7 @@ public class IntSets
     {
         @Override public boolean contains (int value) { return false; }
         @Override public int size () { return 0; }
+        @Override public boolean isEmpty () { return true; }
 
         public Interator interator ()
         {
@@ -233,8 +234,9 @@ public class IntSets
             _s = s;
         }
 
-        @Override public int size () { return _s.size(); }
         @Override public boolean contains (int value) { return _s.contains(value); }
+        @Override public int size () { return _s.size(); }
+        @Override public boolean isEmpty () { return _s.isEmpty(); }
 
         public Interator interator ()
         {