Make ListIteratorWrapper resettable

rfe 39449, from Thomas Schapitz

git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/collections/trunk@400314 13f79535-47bb-0310-9956-ffa450edef68

RELEASE-NOTES.html

@@ -79,6 +79,7 @@ If this causes major headaches to anyone please contact commons-dev at jakarta.a
 <li>ListOrderedMap - additional list-like method, setValue(int,Object)</li>
 <li>ListOrderedMap - additional method, put(int,Object,Object)</li>
 <li>PriorityBuffer - now Serializable [36163]</li>
+<li>ListIteratorWrapper - now implements ResettableListIterator [39449]</li>
 <li>IfClosure - add single argument constructor [38495]</li>
 <li>All/Any/One/None Predicate - allow construction with zero or one predicates [37979]</li>
 </ul>

src/java/org/apache/commons/collections/iterators/ListIteratorWrapper.java

@@ -1,5 +1,5 @@
 /*
- *  Copyright 1999-2004 The Apache Software Foundation
+ *  Copyright 1999-2006 The Apache Software Foundation
  *
  *  Licensed under the Apache License, Version 2.0 (the "License");
  *  you may not use this file except in compliance with the License.
@@ -15,11 +15,13 @@
  */
 package org.apache.commons.collections.iterators;
 
+import java.util.ArrayList;
 import java.util.Iterator;
-import java.util.LinkedList;
-import java.util.ListIterator;
+import java.util.List;
 import java.util.NoSuchElementException;
 
+import org.apache.commons.collections.ResettableListIterator;
+
 /**
  * Converts an iterator into a list iterator by caching the returned entries.
  * <p>
@@ -37,7 +39,7 @@ import java.util.NoSuchElementException;
  * @author Morgan Delagrange
  * @author Stephen Colebourne
  */
-public class ListIteratorWrapper implements ListIterator {
+public class ListIteratorWrapper implements ResettableListIterator {
 
     /** Message used when remove, set or add are called. */
     private static final String UNSUPPORTED_OPERATION_MESSAGE =
@@ -46,7 +48,7 @@ public class ListIteratorWrapper implements ListIterator {
     /** The underlying iterator being decorated. */
     private final Iterator iterator;
     /** The list being used to cache the iterator. */
-    private final LinkedList list = new LinkedList();
+    private final List list = new ArrayList();
 
     /** The current index of this iterator. */
     private int currentIndex = 0;
@@ -176,4 +178,14 @@ public class ListIteratorWrapper implements ListIterator {
         throw new UnsupportedOperationException(UNSUPPORTED_OPERATION_MESSAGE);
     }
 
+    // ResettableIterator interface
+    //-------------------------------------------------------------------------
+    /**
+     * Resets this iterator back to the position at which the iterator
+     * was created.
+     */
+    public void reset()  {
+        currentIndex = 0;
+    }
+
 }

src/test/org/apache/commons/collections/iterators/TestListIteratorWrapper.java

@@ -1,5 +1,5 @@
 /*
- *  Copyright 2001-2004 The Apache Software Foundation
+ *  Copyright 2001-2006 The Apache Software Foundation
  *
  *  Licensed under the Apache License, Version 2.0 (the "License");
  *  you may not use this file except in compliance with the License.
@@ -23,6 +23,7 @@ import java.util.NoSuchElementException;
 
 import junit.framework.Test;
 import junit.framework.TestSuite;
+import org.apache.commons.collections.ResettableListIterator;
 
 /**
  * Tests the ListIteratorWrapper to insure that it simulates
@@ -81,7 +82,7 @@ public class TestListIteratorWrapper extends AbstractTestIterator {
         assertTrue("Iterator should now be empty", ! iter.hasNext() );
 
         try {
-            Object testValue = iter.next();
+            iter.next();
         } catch (Exception e) {
             assertTrue("NoSuchElementException must be thrown", 
                        e.getClass().equals((new NoSuchElementException()).getClass()));
@@ -96,7 +97,7 @@ public class TestListIteratorWrapper extends AbstractTestIterator {
         }
 
         try {
-            Object testValue = iter.previous();
+            iter.previous();
         } catch (Exception e) {
             assertTrue("NoSuchElementException must be thrown", 
                        e.getClass().equals((new NoSuchElementException()).getClass()));
@@ -124,5 +125,27 @@ public class TestListIteratorWrapper extends AbstractTestIterator {
 
     }
 
-}
+    public void testReset() {
+        ResettableListIterator iter = (ResettableListIterator) makeFullIterator();
+        Object first = iter.next();
+        Object second = iter.next();
+        
+        iter.reset();
+        
+        // after reset, there shouldn't be any previous elements
+        assertFalse("No previous elements after reset()", iter.hasPrevious());
 
+        // after reset, the results should be the same as before
+        assertEquals("First element should be the same", first, iter.next());
+        assertEquals("Second elment should be the same", second, iter.next());
+        
+        // after passing the point, where we resetted, continuation should work as expected
+        for (int i = 2; i < testArray.length; i++) {
+            Object testValue = testArray[i];
+            Object iterValue = iter.next();
+
+            assertEquals("Iteration value is correct", testValue, iterValue);
+        }
+    }
+
+}