svn commit: r1127123 - in /commons/proper/collections/trunk/src: java/org/apache/commons/collections/CollectionUtils.java test/org/apache/commons/collections/TestCollectionUtils.java

[brentworden]

Author: brentworden
Date: Tue May 24 16:11:07 2011
New Revision: 1127123

URL: http://svn.apache.org/viewvc?rev=1127123&view=rev
Log:
COLLECTIONS-306.  Added predicated subtract method to CollectionUtils.

Modified:
    
commons/proper/collections/trunk/src/java/org/apache/commons/collections/CollectionUtils.java
    
commons/proper/collections/trunk/src/test/org/apache/commons/collections/TestCollectionUtils.java

Modified: 
commons/proper/collections/trunk/src/java/org/apache/commons/collections/CollectionUtils.java
URL: 
http://svn.apache.org/viewvc/commons/proper/collections/trunk/src/java/org/apache/commons/collections/CollectionUtils.java?rev=1127123&r1=1127122&r2=1127123&view=diff
==============================================================================
--- 
commons/proper/collections/trunk/src/java/org/apache/commons/collections/CollectionUtils.java
 (original)
+++ 
commons/proper/collections/trunk/src/java/org/apache/commons/collections/CollectionUtils.java
 Tue May 24 16:11:07 2011
@@ -33,6 +33,7 @@ import org.apache.commons.collections.co
 import org.apache.commons.collections.collection.TransformedCollection;
 import org.apache.commons.collections.collection.UnmodifiableBoundedCollection;
 import org.apache.commons.collections.collection.UnmodifiableCollection;
+import org.apache.commons.collections.functors.TruePredicate;
 
 /**
  * Provides utility methods and decorators for {@link Collection} instances.
@@ -235,10 +236,31 @@ public class CollectionUtils {
      * @see Collection#removeAll
      */
     public static <O> Collection<O> subtract(final Iterable<? extends O> a, 
final Iterable<? extends O> b) {
+        Predicate<O> p = TruePredicate.truePredicate();
+        return subtract(a, b, p);
+    }
+
+    /**
+     * Returns a new {@link Collection} containing <i>a</i> minus a subset of
+     * <i>b</i>.  Only the elements of <i>b</i> that satisfy the predicate
+     * condition, <i>p</i> are subtracted from <i>a</i>.
+     *
+     * @param a  the collection to subtract from, must not be null
+     * @param b  the collection to subtract, must not be null
+     * @param p  the condition used to determine which elements of <i>b</i> are
+     *        subtracted.
+     * @param <O> the generic type that is able to represent the types 
contained
+     *        in both input collections.
+     * @return a new collection with the results
+     * @see Collection#removeAll
+     */
+    public static <O> Collection<O> subtract(final Iterable<? extends O> a, 
final Iterable<? extends O> b, final Predicate<O> p) {
         ArrayList<O> list = new ArrayList<O>();
         addAll(list, a);
         for (O element : b) {
-            list.remove(element);
+            if (p.evaluate(element)) {
+                list.remove(element);
+            }
         }
         return list;
     }

Modified: 
commons/proper/collections/trunk/src/test/org/apache/commons/collections/TestCollectionUtils.java
URL: 
http://svn.apache.org/viewvc/commons/proper/collections/trunk/src/test/org/apache/commons/collections/TestCollectionUtils.java?rev=1127123&r1=1127122&r2=1127123&view=diff
==============================================================================
--- 
commons/proper/collections/trunk/src/test/org/apache/commons/collections/TestCollectionUtils.java
 (original)
+++ 
commons/proper/collections/trunk/src/test/org/apache/commons/collections/TestCollectionUtils.java
 Tue May 24 16:11:07 2011
@@ -362,6 +362,24 @@ public class TestCollectionUtils extends
     }
 
     @Test
+    public void testSubtractWithPredicate() {
+        // greater than 3
+        Predicate<Number> predicate = new Predicate<Number>() {
+            public boolean evaluate(Number n) {
+                return n.longValue() > 3L;
+            }
+        };
+        
+        Collection<Number> col = CollectionUtils.subtract(iterableA, 
collectionC, predicate);
+        Map<Number, Integer> freq2 = CollectionUtils.getCardinalityMap(col);
+        assertEquals(Integer.valueOf(1), freq2.get(1));
+        assertEquals(Integer.valueOf(2), freq2.get(2));
+        assertEquals(Integer.valueOf(3), freq2.get(3));
+        assertEquals(Integer.valueOf(2), freq2.get(4));
+        assertNull(freq2.get(5));
+    }
+
+    @Test
     public void testIsSubCollectionOfSelf() {
         assertTrue(CollectionUtils.isSubCollection(collectionA, collectionA));
         assertTrue(CollectionUtils.isSubCollection(collectionB, collectionB));