| /* Copyright (c) 2001-2010, The HSQL Development Group |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are met: |
| * |
| * Redistributions of source code must retain the above copyright notice, this |
| * list of conditions and the following disclaimer. |
| * |
| * Redistributions in binary form must reproduce the above copyright notice, |
| * this list of conditions and the following disclaimer in the documentation |
| * and/or other materials provided with the distribution. |
| * |
| * Neither the name of the HSQL Development Group nor the names of its |
| * contributors may be used to endorse or promote products derived from this |
| * software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
| * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG, |
| * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
| * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
| * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| |
| package org.hsqldb.lib; |
| |
| import java.util.NoSuchElementException; |
| |
| /** |
| * An Iterator that returns the elements of a specified array, or other |
| * iterators etc. The collection of objects returned depends on the |
| * constructor used.<p> |
| * |
| * Based on similar Enumerator code by boucherb@users |
| * |
| * @author fred@users |
| * @version 1.9.0 |
| * @since HSQLDB 1.7.2 |
| */ |
| public class WrapperIterator implements Iterator { |
| |
| private static final Object[] emptyelements = new Object[0]; |
| private Object[] elements; |
| private int i; |
| |
| // chained iterators |
| private boolean chained; |
| private Iterator it1; |
| private Iterator it2; |
| |
| /** return only not null elements */ |
| private boolean notNull; |
| |
| /** |
| * Constructor for an empty iterator. <p> |
| */ |
| public WrapperIterator() { |
| this.elements = emptyelements; |
| } |
| |
| /** |
| * Constructor for all elements of the specified array. <p> |
| * |
| * @param elements the array of objects to enumerate |
| */ |
| public WrapperIterator(Object[] elements) { |
| this.elements = elements; |
| } |
| |
| /** |
| * Constructor for not-null elements of specified array. <p> |
| * |
| * @param elements the array of objects to iterate |
| */ |
| public WrapperIterator(Object[] elements, boolean notNull) { |
| this.elements = elements; |
| this.notNull = notNull; |
| } |
| |
| /** |
| * Constructor for a singleton object iterator |
| * |
| * @param element the single object to iterate |
| */ |
| public WrapperIterator(Object element) { |
| this.elements = new Object[]{ element }; |
| } |
| |
| /** |
| * Constructor for a chained iterator that returns the elements of the two |
| * specified iterators. |
| */ |
| public WrapperIterator(Iterator it1, Iterator it2) { |
| |
| this.it1 = it1; |
| this.it2 = it2; |
| chained = true; |
| } |
| |
| /** |
| * Tests if this iterator contains more elements. <p> |
| * |
| * @return <code>true</code> if this iterator contains more elements; |
| * <code>false</code> otherwise. |
| */ |
| public boolean hasNext() { |
| |
| // for chained iterators |
| if (chained) { |
| if (it1 == null) { |
| if (it2 == null) { |
| return false; |
| } |
| |
| if (it2.hasNext()) { |
| return true; |
| } |
| |
| it2 = null; |
| |
| return false; |
| } else { |
| if (it1.hasNext()) { |
| return true; |
| } |
| |
| it1 = null; |
| |
| return hasNext(); |
| } |
| } |
| |
| // for other interators |
| if (elements == null) { |
| return false; |
| } |
| |
| for (; notNull && i < elements.length && elements[i] == null; i++) {} |
| |
| if (i < elements.length) { |
| return true; |
| } else { |
| |
| // release elements for garbage collection |
| elements = null; |
| |
| return false; |
| } |
| } |
| |
| /** |
| * Returns the next element. |
| * |
| * @return the next element |
| * @throws NoSuchElementException if there is no next element |
| */ |
| public Object next() { |
| |
| // for chained iterators |
| if (chained) { |
| if (it1 == null) { |
| if (it2 == null) { |
| throw new NoSuchElementException(); |
| } |
| |
| if (it2.hasNext()) { |
| return it2.next(); |
| } |
| |
| it2 = null; |
| |
| next(); |
| } else { |
| if (it1.hasNext()) { |
| return it1.next(); |
| } |
| |
| it1 = null; |
| |
| next(); |
| } |
| } |
| |
| // for other itertors |
| if (hasNext()) { |
| return elements[i++]; |
| } |
| |
| throw new NoSuchElementException(); |
| } |
| |
| public int nextInt() { |
| throw new NoSuchElementException(); |
| } |
| |
| public long nextLong() { |
| throw new NoSuchElementException(); |
| } |
| |
| public void remove() { |
| throw new NoSuchElementException(); |
| } |
| |
| public void setValue(Object value) { |
| throw new NoSuchElementException(); |
| } |
| } |