| /* |
| * 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 org.apache.directory.server.i18n.I18n; |
| import org.apache.directory.shared.ldap.model.cursor.AbstractTupleCursor; |
| import org.apache.directory.shared.ldap.model.cursor.InvalidCursorPositionException; |
| import org.apache.directory.shared.ldap.model.cursor.Tuple; |
| |
| import java.util.Comparator; |
| |
| import jdbm.helper.TupleBrowser; |
| import jdbm.btree.BTree; |
| |
| |
| /** |
| * Cursor over a set of values for the same key which are store in another |
| * BTree. This Cursor is limited to the same key and it's tuples will always |
| * return the same key. |
| * |
| * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> |
| */ |
| public class KeyTupleBTreeCursor<K,V> extends AbstractTupleCursor<K,V> |
| { |
| private final Comparator<V> comparator; |
| private final BTree btree; |
| private final K key; |
| |
| private jdbm.helper.Tuple valueTuple = new jdbm.helper.Tuple(); |
| private Tuple<K,V> returnedTuple = new Tuple<K,V>(); |
| private TupleBrowser browser; |
| private boolean valueAvailable; |
| |
| |
| /** |
| * Creates a Cursor over the tuples of a JDBM BTree. |
| * |
| * @param btree the JDBM BTree to build a Cursor over |
| * @param key the constant key for which values are returned |
| * @param comparator the Comparator used to determine <b>key</b> ordering |
| * @throws Exception of there are problems accessing the BTree |
| */ |
| public KeyTupleBTreeCursor( BTree btree, K key, Comparator<V> comparator ) throws Exception |
| { |
| this.key = key; |
| this.btree = btree; |
| this.comparator = comparator; |
| this.browser = btree.browse(); |
| } |
| |
| |
| private void clearValue() |
| { |
| returnedTuple.setKey( key ); |
| returnedTuple.setValue( null ); |
| valueAvailable = false; |
| } |
| |
| |
| public boolean available() |
| { |
| return valueAvailable; |
| } |
| |
| |
| public void beforeKey( K key ) throws Exception |
| { |
| throw new UnsupportedOperationException( I18n.err( I18n.ERR_446 ) ); |
| } |
| |
| |
| public void afterKey( K key ) throws Exception |
| { |
| throw new UnsupportedOperationException( I18n.err( I18n.ERR_446 ) ); |
| } |
| |
| |
| public void beforeValue( K key, V value ) throws Exception |
| { |
| checkNotClosed( "beforeValue()" ); |
| if ( key != null && ! key.equals( this.key ) ) |
| { |
| throw new UnsupportedOperationException( I18n.err( I18n.ERR_446 ) ); |
| } |
| |
| browser = btree.browse( value ); |
| clearValue(); |
| } |
| |
| |
| @SuppressWarnings("unchecked") |
| public void afterValue( K key, V value ) throws Exception |
| { |
| if ( key != null && ! key.equals( this.key ) ) |
| { |
| throw new UnsupportedOperationException( I18n.err( I18n.ERR_446 ) ); |
| } |
| |
| browser = btree.browse( value ); |
| |
| /* |
| * While the next value is less than or equal to the element keep |
| * advancing forward to the next item. If we cannot advance any |
| * further then stop and return. If we find a value greater than |
| * the element then we stop, backup, and return so subsequent calls |
| * to getNext() will return a value greater than the element. |
| */ |
| while ( browser.getNext( valueTuple ) ) |
| { |
| checkNotClosed( "afterValue" ); |
| |
| V next = ( V ) valueTuple.getKey(); |
| |
| int nextCompared = comparator.compare( next, value ); |
| |
| if ( nextCompared <= 0 ) |
| { |
| // just continue |
| } |
| else if ( nextCompared > 0 ) |
| { |
| /* |
| * If we just have values greater than the element argument |
| * then we are before the first element and cannot backup, and |
| * the call below to getPrevious() will fail. In this special |
| * case we just reset the Cursor's browser and return. |
| */ |
| if ( browser.getPrevious( valueTuple ) ) |
| { |
| } |
| else |
| { |
| browser = btree.browse( this.key ); |
| } |
| |
| clearValue(); |
| return; |
| } |
| } |
| |
| clearValue(); |
| } |
| |
| |
| /** |
| * Positions this Cursor over the same keys before the value of the |
| * supplied valueTuple. The supplied element Tuple's key is not considered at |
| * all. |
| * |
| * @param element the valueTuple who's value is used to position this Cursor |
| * @throws Exception if there are failures to position the Cursor |
| */ |
| public void before( Tuple<K,V> element ) throws Exception |
| { |
| checkNotClosed( "before()" ); |
| browser = btree.browse( element.getValue() ); |
| clearValue(); |
| } |
| |
| |
| public void after( Tuple<K,V> element ) throws Exception |
| { |
| afterValue( key, element.getValue() ); |
| } |
| |
| |
| public void beforeFirst() throws Exception |
| { |
| checkNotClosed( "beforeFirst()" ); |
| browser = btree.browse(); |
| clearValue(); |
| } |
| |
| |
| public void afterLast() throws Exception |
| { |
| checkNotClosed( "afterLast()" ); |
| browser = btree.browse( null ); |
| } |
| |
| |
| public boolean first() throws Exception |
| { |
| beforeFirst(); |
| return next(); |
| } |
| |
| |
| public boolean last() throws Exception |
| { |
| afterLast(); |
| return previous(); |
| } |
| |
| |
| @SuppressWarnings("unchecked") |
| public boolean previous() throws Exception |
| { |
| checkNotClosed( "previous()" ); |
| if ( browser.getPrevious( valueTuple ) ) |
| { |
| // work around to fix direction change problem with jdbm browser |
| if ( returnedTuple.getValue() != null && |
| comparator.compare( ( V ) valueTuple.getKey(), returnedTuple.getValue() ) == 0 ) |
| { |
| browser.getPrevious( valueTuple ) ; |
| } |
| returnedTuple.setKey( key ); |
| returnedTuple.setValue( ( V ) valueTuple.getKey() ); |
| return valueAvailable = true; |
| } |
| else |
| { |
| clearValue(); |
| return false; |
| } |
| } |
| |
| |
| @SuppressWarnings("unchecked") |
| public boolean next() throws Exception |
| { |
| checkNotClosed( "next()" ); |
| if ( browser.getNext( valueTuple ) ) |
| { |
| // work around to fix direction change problem with jdbm browser |
| if ( returnedTuple.getValue() != null && |
| comparator.compare( ( V ) valueTuple.getKey(), returnedTuple.getValue() ) == 0 ) |
| { |
| browser.getNext( valueTuple ) ; |
| } |
| returnedTuple.setKey( key ); |
| returnedTuple.setValue( ( V ) valueTuple.getKey() ); |
| return valueAvailable = true; |
| } |
| else |
| { |
| clearValue(); |
| return false; |
| } |
| } |
| |
| |
| public Tuple<K,V> get() throws Exception |
| { |
| checkNotClosed( "get()" ); |
| if ( valueAvailable ) |
| { |
| return returnedTuple; |
| } |
| |
| throw new InvalidCursorPositionException(); |
| } |
| |
| |
| public boolean isElementReused() |
| { |
| return true; |
| } |
| } |