| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| * |
| */ |
| package org.apache.directory.server.core.partition.impl.btree.jdbm; |
| |
| |
| import java.io.IOException; |
| import java.util.Iterator; |
| import java.util.NoSuchElementException; |
| |
| import javax.naming.NamingException; |
| |
| import org.apache.directory.shared.ldap.exception.LdapNamingException; |
| import org.apache.directory.shared.ldap.message.ResultCodeEnum; |
| |
| import jdbm.btree.BTree; |
| import jdbm.helper.TupleBrowser; |
| |
| |
| /** |
| * A NamingEnumeration that returns keys in a BTree. This is used specifically |
| * for situations when tables support duplicate keys and a BTree is used for |
| * storing the values for that key. This enumeration thus advances a browser forwards |
| * returning keys from a BTree as values. |
| * |
| * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> |
| * @version $Rev$ |
| */ |
| public class BTreeIterator implements Iterator |
| { |
| private final jdbm.helper.Tuple jdbmTuple = new jdbm.helper.Tuple(); |
| private TupleBrowser browser; |
| private boolean success = false; |
| private boolean doAscending = true; |
| |
| |
| BTreeIterator( BTree tree, boolean doAscending ) throws NamingException |
| { |
| this.doAscending = doAscending; |
| |
| try |
| { |
| if ( doAscending ) |
| { |
| browser = tree.browse(); |
| } |
| else |
| { |
| browser = tree.browse( null ); |
| } |
| |
| prefetch(); |
| } |
| catch ( IOException e ) |
| { |
| LdapNamingException lne = new LdapNamingException( "Failure on btree: " + e.getMessage(), |
| ResultCodeEnum.OTHER ); |
| lne.setRootCause( e ); |
| throw lne; |
| } |
| } |
| |
| |
| private void prefetch() throws IOException |
| { |
| if ( doAscending ) |
| { |
| success = browser.getNext( jdbmTuple ); |
| } |
| else |
| { |
| success = browser.getPrevious( jdbmTuple ); |
| } |
| } |
| |
| |
| public boolean hasNext() |
| { |
| return success; |
| } |
| |
| |
| public Object next() |
| { |
| if ( ! success ) |
| { |
| throw new NoSuchElementException(); |
| } |
| |
| Object next = jdbmTuple.getKey(); |
| try |
| { |
| prefetch(); |
| } |
| catch ( IOException e ) |
| { |
| throw new NoSuchElementException( "Failure on btree: " + e.getMessage() ); |
| } |
| return next; |
| } |
| |
| |
| public void remove() |
| { |
| throw new UnsupportedOperationException(); |
| } |
| } |