001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, 013 * software distributed under the License is distributed on an 014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 * KIND, either express or implied. See the License for the 016 * specific language governing permissions and limitations 017 * under the License. 018 */ 019 package org.apache.directory.server.core.avltree; 020 021 022 import org.apache.directory.server.i18n.I18n; 023 import org.apache.directory.server.xdbm.AbstractTupleCursor; 024 import org.apache.directory.server.xdbm.Tuple; 025 import org.apache.directory.shared.ldap.cursor.InvalidCursorPositionException; 026 027 028 /** 029 * Cursor over a set of values for the same key which are store in an in 030 * memory AvlTree. This Cursor is limited to the same key and it's tuples 031 * will always return the same key. 032 * 033 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> 034 * @version $Rev$, $Date$ 035 */ 036 public class KeyTupleAvlCursor<K,V> extends AbstractTupleCursor<K,V> 037 { 038 private final AvlTreeCursor<V> wrapped; 039 private final K key; 040 041 private Tuple<K,V> returnedTuple = new Tuple<K,V>(); 042 private boolean valueAvailable; 043 044 045 /** 046 * Creates a Cursor over the tuples of an AvlTree. 047 * 048 * @param avlTree the AvlTree to build a Tuple returning Cursor over 049 * @param key the constant key for which values are returned 050 */ 051 public KeyTupleAvlCursor( AvlTree<V> avlTree, K key ) 052 { 053 this.key = key; 054 this.wrapped = new AvlTreeCursor<V>( avlTree ); 055 } 056 057 058 private void clearValue() 059 { 060 returnedTuple.setKey( key ); 061 returnedTuple.setValue( null ); 062 valueAvailable = false; 063 } 064 065 066 public boolean available() 067 { 068 return valueAvailable; 069 } 070 071 072 public void beforeKey( K key ) throws Exception 073 { 074 throw new UnsupportedOperationException( I18n.err( I18n.ERR_446 ) ); 075 } 076 077 078 public void afterKey( K key ) throws Exception 079 { 080 throw new UnsupportedOperationException( I18n.err( I18n.ERR_446 ) ); 081 } 082 083 084 public void beforeValue( K key, V value ) throws Exception 085 { 086 checkNotClosed( "beforeValue()" ); 087 if ( key != null && ! key.equals( this.key ) ) 088 { 089 throw new UnsupportedOperationException( I18n.err( I18n.ERR_446 ) ); 090 } 091 092 wrapped.before( value ); 093 clearValue(); 094 } 095 096 097 public void afterValue( K key, V value ) throws Exception 098 { 099 checkNotClosed( "afterValue()" ); 100 if ( key != null && ! key.equals( this.key ) ) 101 { 102 throw new UnsupportedOperationException( I18n.err( I18n.ERR_446 ) ); 103 } 104 105 wrapped.after( value ); 106 clearValue(); 107 } 108 109 110 /** 111 * Positions this Cursor over the same keys before the value of the 112 * supplied element Tuple. The supplied element Tuple's key is not 113 * considered at all. 114 * 115 * @param element the valueTuple who's value is used to position this Cursor 116 * @throws Exception if there are failures to position the Cursor 117 */ 118 public void before( Tuple<K,V> element ) throws Exception 119 { 120 checkNotClosed( "before()" ); 121 wrapped.before( element.getValue() ); 122 clearValue(); 123 } 124 125 126 public void after( Tuple<K,V> element ) throws Exception 127 { 128 checkNotClosed( "after()" ); 129 wrapped.after( element.getValue() ); 130 clearValue(); 131 } 132 133 134 public void beforeFirst() throws Exception 135 { 136 checkNotClosed( "beforeFirst()" ); 137 wrapped.beforeFirst(); 138 clearValue(); 139 } 140 141 142 public void afterLast() throws Exception 143 { 144 checkNotClosed( "afterLast()" ); 145 wrapped.afterLast(); 146 clearValue(); 147 } 148 149 150 public boolean first() throws Exception 151 { 152 beforeFirst(); 153 return next(); 154 } 155 156 157 public boolean last() throws Exception 158 { 159 afterLast(); 160 return previous(); 161 } 162 163 164 public boolean previous() throws Exception 165 { 166 checkNotClosed( "previous()" ); 167 if ( wrapped.previous() ) 168 { 169 returnedTuple.setKey( key ); 170 returnedTuple.setValue( wrapped.get() ); 171 return valueAvailable = true; 172 } 173 else 174 { 175 clearValue(); 176 return false; 177 } 178 } 179 180 181 public boolean next() throws Exception 182 { 183 checkNotClosed( "next()" ); 184 if ( wrapped.next() ) 185 { 186 returnedTuple.setKey( key ); 187 returnedTuple.setValue( wrapped.get() ); 188 return valueAvailable = true; 189 } 190 else 191 { 192 clearValue(); 193 return false; 194 } 195 } 196 197 198 public Tuple<K,V> get() throws Exception 199 { 200 checkNotClosed( "get()" ); 201 if ( valueAvailable ) 202 { 203 return returnedTuple; 204 } 205 206 throw new InvalidCursorPositionException(); 207 } 208 209 210 public boolean isElementReused() 211 { 212 return true; 213 } 214 }