Implemented retainAll().

git-svn-id: https://samskivert.googlecode.com/svn/trunk@742 6335cc39-0255-0410-8fd6-9bcaacd3b74c

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

@@ -1,5 +1,5 @@
 //
-// $Id: ArrayIntSet.java,v 1.4 2002/04/18 00:09:17 mdb Exp $
+// $Id: ArrayIntSet.java,v 1.5 2002/05/16 20:50:31 mdb Exp $
 //
 // samskivert library - useful routines for java programs
 // Copyright (C) 2001 Michael Bayne
@@ -236,7 +236,32 @@ public class ArrayIntSet extends AbstractSet
     // documentation inherited from interface
     public boolean retainAll (Collection c)
     {
-        throw new UnsupportedOperationException();
+        if (c instanceof ArrayIntSet) {
+            ArrayIntSet other = (ArrayIntSet)c;
+            // make a new array that will hold the union of our two arrays
+            // (this is preferable to the complicated process of repeated
+            // shrinking or swapping)
+            int[] combined = new int[Math.min(_values.length,
+                                              other._values.length)];
+            int nsize = 0;
+            for (int ii = 0; ii < _size; ii++) {
+                if (other.contains(_values[ii])) {
+                    combined[nsize++] = _values[ii];
+                }
+            }
+
+            // keep track of whether or not things changed
+            boolean changed = (_size != nsize);
+
+            // stuff the new values into the right place
+            _values = combined;
+            _size = nsize;
+
+            return changed;
+
+        } else {
+            throw new UnsupportedOperationException();
+        }
     }
 
     // documentation inherited from interface
@@ -252,7 +277,12 @@ public class ArrayIntSet extends AbstractSet
         if (o instanceof ArrayIntSet) {
             ArrayIntSet other = (ArrayIntSet)o;
             if (other._size == _size) {
-                return Arrays.equals(_values, other._values);
+                for (int ii = 0; ii < _size; ii++) {
+                    if (_values[ii] != other._values[ii]) {
+                        return false;
+                    }
+                }
+                return true;
             }
         }
 
@@ -269,6 +299,14 @@ public class ArrayIntSet extends AbstractSet
         return hashCode;
     }
 
+    /**
+     * Returns a string representation of this instance.
+     */
+    public String toString ()
+    {
+        return StringUtil.toString(iterator());
+    }
+
     /**
      * Performs a binary search on our values array, looking for the
      * specified value. Swiped from <code>java.util.Arrays</code> because

projects/samskivert/tests/src/java/com/samskivert/util/ArrayIntSetTest.java

@@ -1,5 +1,5 @@
 //
-// $Id: ArrayIntSetTest.java,v 1.2 2002/04/11 04:07:42 mdb Exp $
+// $Id: ArrayIntSetTest.java,v 1.3 2002/05/16 20:50:31 mdb Exp $
 //
 // samskivert library - useful routines for java programs
 // Copyright (C) 2001 Michael Bayne
@@ -49,6 +49,25 @@ public class ArrayIntSetTest extends TestCase
         int[] setvals = set.toIntArray();
 
         assertTrue("values equal", Arrays.equals(values, setvals));
+
+        ArrayIntSet set1 = new ArrayIntSet();
+        set1.add(new int[] { 1, 2, 3, 5, 7, 12, 19, 35 });
+        ArrayIntSet set2 = new ArrayIntSet();
+        set2.add(new int[] { 3, 4, 5, 11, 13, 17, 19, 25 });
+
+        ArrayIntSet set3 = new ArrayIntSet();
+        set3.add(new int[] { 3, 5, 19 });
+
+        // intersect sets 1 and 2; making sure that retainAll() returns
+        // true to indicate that set 1 was modified
+        assertTrue("retain modifies", set1.retainAll(set2));
+
+        // make sure the intersections were correct
+        assertTrue("intersection", set1.equals(set3));
+
+        // make sure that retainAll returns false if we do something that
+        // doesn't modify the set
+        assertTrue("retain didn't modify", !set1.retainAll(set3));
     }
 
     public static Test suite ()