cvs commit: jakarta-commons/collections/src/java/org/apache/commons/collections IteratorUtils.java

[sc...@apache.org]

scolebourne    2003/01/15 13:55:43

  Modified:    collections/src/java/org/apache/commons/collections
                        IteratorUtils.java
  Log:
  Make Empty Iterators implement Resetable
  Handle Unmodifiable/Resetable combination iterators
  Expose Resetable Iterators as return types from methods
  
  Revision  Changes    Path
  1.9       +97 -29    jakarta-commons/collections/src/java/org/apache/commons/collections/IteratorUtils.java
  
  Index: IteratorUtils.java
  ===================================================================
  RCS file: /home/cvs/jakarta-commons/collections/src/java/org/apache/commons/collections/IteratorUtils.java,v
  retrieving revision 1.8
  retrieving revision 1.9
  diff -u -r1.8 -r1.9
  --- IteratorUtils.java	10 Jan 2003 20:21:23 -0000	1.8
  +++ IteratorUtils.java	15 Jan 2003 21:55:43 -0000	1.9
  @@ -83,6 +83,8 @@
   import org.apache.commons.collections.iterators.LoopingIterator;
   import org.apache.commons.collections.iterators.ObjectArrayIterator;
   import org.apache.commons.collections.iterators.ObjectArrayListIterator;
  +import org.apache.commons.collections.iterators.ResetableIterator;
  +import org.apache.commons.collections.iterators.ResetableListIterator;
   import org.apache.commons.collections.iterators.SingletonIterator;
   import org.apache.commons.collections.iterators.SingletonListIterator;
   import org.apache.commons.collections.iterators.TransformIterator;
  @@ -91,9 +93,10 @@
    * instances. The implementations are provided in the 
    * {@link org.apache.commons.collections.iterators} subpackage.
    *
  - * @author <a href="mailto:scolebourne@joda.org">Stephen Colebourne</a>
  - * @version $Revision$ $Date$
    * @since Commons Collections 2.1
  + * @version $Revision$ $Date$
  + * 
  + * @author Stephen Colebourne
    */
   public class IteratorUtils {
       // validation is done in this class in certain cases because the
  @@ -125,8 +128,8 @@
        *
        * @return  an iterator over nothing
        */
  -    public static Iterator emptyIterator() {
  -        return EMPTY_ITERATOR;
  +    public static ResetableIterator emptyIterator() {
  +        return (ResetableIterator) EMPTY_ITERATOR;
       }
   
       /**
  @@ -137,8 +140,8 @@
        *
        * @return  a list iterator over nothing
        */
  -    public static ListIterator emptyListIterator() {
  -        return EMPTY_LIST_ITERATOR;
  +    public static ResetableListIterator emptyListIterator() {
  +        return (ResetableListIterator) EMPTY_LIST_ITERATOR;
       }
   
       /**
  @@ -150,7 +153,7 @@
        * @param object  the single object over which to iterate
        * @return  a singleton iterator over the object
        */
  -    public static Iterator singletonIterator(Object object) {
  +    public static ResetableIterator singletonIterator(Object object) {
           return new SingletonIterator(object);
       }
   
  @@ -163,7 +166,7 @@
        * @param object  the single object over which to iterate
        * @return  a singleton list iterator over the object
        */
  -    public static ListIterator singletonListIterator(Object object) {
  +    public static ResetableListIterator singletonListIterator(Object object) {
           return new SingletonListIterator(object);
       }
   
  @@ -177,7 +180,7 @@
        * @return  an iterator over the array
        * @throws NullPointerException if array is null
        */
  -    public static Iterator arrayIterator(Object[] array) {
  +    public static ResetableIterator arrayIterator(Object[] array) {
           return new ObjectArrayIterator(array);
       }
   
  @@ -192,7 +195,7 @@
        * @throws IllegalArgumentException if the array is not an array
        * @throws NullPointerException if array is null
        */
  -    public static Iterator arrayIterator(Object array) {
  +    public static ResetableIterator arrayIterator(Object array) {
           return new ArrayIterator(array);
       }
   
  @@ -205,7 +208,7 @@
        * @throws IndexOutOfBoundsException if start is less than zero
        * @throws NullPointerException if array is null
        */
  -    public static Iterator arrayIterator(Object[] array, int start) {
  +    public static ResetableIterator arrayIterator(Object[] array, int start) {
           return new ObjectArrayIterator(array, start);
       }
   
  @@ -222,7 +225,7 @@
        * @throws IndexOutOfBoundsException if start is less than zero
        * @throws NullPointerException if array is null
        */
  -    public static Iterator arrayIterator(Object array, int start) {
  +    public static ResetableIterator arrayIterator(Object array, int start) {
           return new ArrayIterator(array, start);
       }
   
  @@ -237,7 +240,7 @@
        * @throws IllegalArgumentException if end is before start
        * @throws NullPointerException if array is null
        */
  -    public static Iterator arrayIterator(Object[] array, int start, int end) {
  +    public static ResetableIterator arrayIterator(Object[] array, int start, int end) {
           return new ObjectArrayIterator(array, start, end);
       }
   
  @@ -256,7 +259,7 @@
        * @throws IllegalArgumentException if end is before start
        * @throws NullPointerException if array is null
        */
  -    public static Iterator arrayIterator(Object array, int start, int end) {
  +    public static ResetableIterator arrayIterator(Object array, int start, int end) {
           return new ArrayIterator(array, start, end);
       }
   
  @@ -267,7 +270,7 @@
        * @return  a list iterator over the array
        * @throws NullPointerException if array is null
        */
  -    public static ListIterator arrayListIterator(Object[] array) {
  +    public static ResetableListIterator arrayListIterator(Object[] array) {
           return new ObjectArrayListIterator(array);
       }
   
  @@ -282,7 +285,7 @@
        * @throws IllegalArgumentException if the array is not an array
        * @throws NullPointerException if array is null
        */
  -    public static ListIterator arrayListIterator(Object array) {
  +    public static ResetableListIterator arrayListIterator(Object array) {
           return new ArrayListIterator(array);
       }
   
  @@ -295,7 +298,7 @@
        * @throws IndexOutOfBoundsException if start is less than zero
        * @throws NullPointerException if array is null
        */
  -    public static ListIterator arrayListIterator(Object[] array, int start) {
  +    public static ResetableListIterator arrayListIterator(Object[] array, int start) {
           return new ObjectArrayListIterator(array, start);
       }
   
  @@ -312,7 +315,7 @@
        * @throws IndexOutOfBoundsException if start is less than zero
        * @throws NullPointerException if array is null
        */
  -    public static ListIterator arrayListIterator(Object array, int start) {
  +    public static ResetableListIterator arrayListIterator(Object array, int start) {
           return new ArrayListIterator(array, start);
       }
   
  @@ -327,7 +330,7 @@
        * @throws IllegalArgumentException if end is before start
        * @throws NullPointerException if array is null
        */
  -    public static ListIterator arrayListIterator(Object[] array, int start, int end) {
  +    public static ResetableListIterator arrayListIterator(Object[] array, int start, int end) {
           return new ObjectArrayListIterator(array, start, end);
       }
       
  @@ -346,7 +349,7 @@
        * @throws IllegalArgumentException if end is before start
        * @throws NullPointerException if array is null
        */
  -    public static ListIterator arrayListIterator(Object array, int start, int end) {
  +    public static ResetableListIterator arrayListIterator(Object array, int start, int end) {
           return new ArrayListIterator(array, start, end);
       }
       
  @@ -358,10 +361,13 @@
        * will always throw an {@link UnsupportedOperationException} for
        * the {@link Iterator#remove} method.
        *
  -     * @param iterator The iterator to make immutable.
  -     * @return An immutable version of the iterator.
  +     * @param iterator  the iterator to make immutable
  +     * @return an immutable version of the iterator
        */
       public static Iterator unmodifiableIterator(Iterator iterator) {
  +        if (iterator instanceof ResetableIterator) {
  +            return new ResetableUnmodifiableIterator((ResetableIterator) iterator);
  +        }
           return new UnmodifiableIterator(iterator);
       }
       
  @@ -371,10 +377,13 @@
        * the {@link Iterator#remove}, {@link ListIterator#add} and
        * {@link ListIterator#set} methods.
        *
  -     * @param listIterator The iterator to make immutable.
  -     * @return An immutable version of the iterator.
  +     * @param listIterator  the iterator to make immutable
  +     * @return an immutable version of the iterator
        */
       public static ListIterator unmodifiableListIterator(ListIterator listIterator) {
  +        if (listIterator instanceof ResetableListIterator) {
  +            return new ResetableUnmodifiableListIterator((ResetableListIterator) listIterator);
  +        }
           return new UnmodifiableListIterator(listIterator);
       }
   
  @@ -545,7 +554,7 @@
        * @param coll  the collection to iterate over, not null
        * @throws NullPointerException if the collection is null
        */
  -    public static Iterator loopingIterator(Collection coll) {
  +    public static ResetableIterator loopingIterator(Collection coll) {
           if (coll == null) {
               throw new NullPointerException("Collection must not be null");
           }
  @@ -751,7 +760,7 @@
       /**
        * EmptyIterator class
        */
  -    static class EmptyIterator implements Iterator {
  +    static class EmptyIterator implements ResetableIterator {
           
           /**
            * @see java.util.Iterator#hasNext()
  @@ -773,13 +782,20 @@
           public void remove() {
               throw new UnsupportedOperationException("remove() not supported for empty Iterator");
           }
  +        
  +        /**
  +         * Reset the iterator
  +         */
  +        public void reset() {
  +            // do nothing
  +        }
   
       }
       
       /**
        * EmptyListIterator class
        */
  -    static class EmptyListIterator extends EmptyIterator implements ListIterator {
  +    static class EmptyListIterator extends EmptyIterator implements ResetableListIterator {
           
           /**
            * @see java.util.ListIterator#hasPrevious()
  @@ -831,6 +847,7 @@
        * always throws an {@link java.lang.UnsupportedOperationException}.
        *
        * @author <a href="mailto:rich@rd.gen.nz">Rich Dougherty</a>
  +     * @author Stephen Colebourne
        */
       static class UnmodifiableIterator implements Iterator, Serializable {
   
  @@ -842,7 +859,7 @@
           /**
            * Create an UnmodifiableIterator.
            *
  -         * @param delegate The delegate to pass all calls to.
  +         * @param delegate  the delegate to pass all calls to
            */
           public UnmodifiableIterator(Iterator delegate) {
               this.delegate = delegate;
  @@ -863,6 +880,31 @@
       }
   
       /**
  +     * An unmodifiable resetable iterator.
  +     *
  +     * @author Stephen Colebourne
  +     */
  +    static class ResetableUnmodifiableIterator extends UnmodifiableIterator implements ResetableIterator {
  +        
  +        /**
  +         * Create a ResetableUnmodifiableIterator.
  +         *
  +         * @param delegate  the delegate to pass all calls to
  +         */
  +        public ResetableUnmodifiableIterator(ResetableIterator delegate) {
  +            super(delegate);
  +        }
  +
  +        /**
  +         * Reset the iterator
  +         */
  +        public void reset() {
  +            ((ResetableIterator) delegate).reset();
  +        }
  +
  +    }
  +    
  +    /**
        * A wrapper for an {@link java.util.ListIterator} which makes it immutable.
        * All calls are passed through to the delegate. The {@link #remove()},
        * {@link #add(Object)} and (@link #set(Object)} methods always throw an
  @@ -923,4 +965,30 @@
               throw new UnsupportedOperationException("This iterator is immutable");
           }
       }
  +    
  +    /**
  +     * An unmodifiable resetable list iterator.
  +     *
  +     * @author Stephen Colebourne
  +     */
  +    static class ResetableUnmodifiableListIterator extends UnmodifiableListIterator implements ResetableListIterator {
  +            
  +        /**
  +         * Create a ResetableUnmodifiableListIterator.
  +         *
  +         * @param delegate  the delegate to pass all calls to
  +         */
  +        public ResetableUnmodifiableListIterator(ResetableListIterator delegate) {
  +            super(delegate);
  +        }
  +    
  +        /**
  +         * Reset the iterator
  +         */
  +        public void reset() {
  +            ((ResetableListIterator) delegate).reset();
  +        }
  +    
  +    }
  +        
   }
  
  
  

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