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 */ 020 package org.apache.directory.server.xdbm.search.impl; 021 022 023 import org.apache.directory.server.i18n.I18n; 024 import org.apache.directory.server.xdbm.AbstractIndexCursor; 025 import org.apache.directory.server.xdbm.ForwardIndexEntry; 026 import org.apache.directory.server.xdbm.Index; 027 import org.apache.directory.server.xdbm.IndexCursor; 028 import org.apache.directory.server.xdbm.IndexEntry; 029 import org.apache.directory.server.xdbm.Store; 030 import org.apache.directory.shared.ldap.cursor.InvalidCursorPositionException; 031 import org.apache.directory.shared.ldap.entry.ServerEntry; 032 033 034 /** 035 * A Cursor traversing candidates matching a Substring assertion expression. 036 * 037 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> 038 * @version $Rev$ 039 */ 040 public class SubstringCursor<ID> extends AbstractIndexCursor<String, ServerEntry, ID> 041 { 042 private static final String UNSUPPORTED_MSG = I18n.err( I18n.ERR_725 ); 043 private final boolean hasIndex; 044 private final IndexCursor<String, ServerEntry, ID> wrapped; 045 private final SubstringEvaluator<ID> evaluator; 046 private final ForwardIndexEntry<String, ServerEntry, ID> indexEntry = new ForwardIndexEntry<String, ServerEntry, ID>(); 047 private boolean available = false; 048 049 050 @SuppressWarnings("unchecked") 051 public SubstringCursor( Store<ServerEntry, ID> db, final SubstringEvaluator<ID> substringEvaluator ) 052 throws Exception 053 { 054 evaluator = substringEvaluator; 055 hasIndex = db.hasIndexOn( evaluator.getExpression().getAttribute() ); 056 057 if ( hasIndex ) 058 { 059 wrapped = ( ( Index<String, ServerEntry, ID> ) db.getIndex( evaluator.getExpression().getAttribute() ) ) 060 .forwardCursor(); 061 } 062 else 063 { 064 /* 065 * There is no index on the attribute here. We have no choice but 066 * to perform a full table scan but need to leverage an index for the 067 * wrapped Cursor. We know that all entries are listed under 068 * the ndn index and so this will enumerate over all entries. The 069 * substringEvaluator is used in an assertion to constrain the 070 * result set to only those entries matching the pattern. The 071 * substringEvaluator handles all the details of normalization and 072 * knows to use it, when it itself detects the lack of an index on 073 * the node's attribute. 074 */ 075 wrapped = db.getNdnIndex().forwardCursor(); 076 } 077 } 078 079 080 public boolean available() 081 { 082 return available; 083 } 084 085 086 public void beforeValue( ID id, String value ) throws Exception 087 { 088 throw new UnsupportedOperationException( UNSUPPORTED_MSG ); 089 } 090 091 092 public void afterValue( ID id, String value ) throws Exception 093 { 094 throw new UnsupportedOperationException( UNSUPPORTED_MSG ); 095 } 096 097 098 public void before( IndexEntry<String, ServerEntry, ID> element ) throws Exception 099 { 100 throw new UnsupportedOperationException( UNSUPPORTED_MSG ); 101 } 102 103 104 public void after( IndexEntry<String, ServerEntry, ID> element ) throws Exception 105 { 106 throw new UnsupportedOperationException( UNSUPPORTED_MSG ); 107 } 108 109 110 public void beforeFirst() throws Exception 111 { 112 checkNotClosed( "beforeFirst()" ); 113 if ( evaluator.getExpression().getInitial() != null && hasIndex ) 114 { 115 ForwardIndexEntry<String, ServerEntry, ID> indexEntry = new ForwardIndexEntry<String, ServerEntry, ID>(); 116 indexEntry.setValue( evaluator.getExpression().getInitial() ); 117 wrapped.before( indexEntry ); 118 } 119 else 120 { 121 wrapped.beforeFirst(); 122 } 123 124 clear(); 125 } 126 127 128 private void clear() 129 { 130 available = false; 131 indexEntry.setObject( null ); 132 indexEntry.setId( null ); 133 indexEntry.setValue( null ); 134 } 135 136 137 public void afterLast() throws Exception 138 { 139 checkNotClosed( "afterLast()" ); 140 141 // to keep the cursor always *after* the last matched tuple 142 // This fixes an issue if the last matched tuple is also the last record present in the 143 // index. In this case the wrapped cursor is positioning on the last tuple instead of positioning after that 144 wrapped.afterLast(); 145 clear(); 146 } 147 148 149 public boolean first() throws Exception 150 { 151 beforeFirst(); 152 return next(); 153 } 154 155 156 private boolean evaluateCandidate( IndexEntry<String, ServerEntry, ID> indexEntry ) throws Exception 157 { 158 if ( hasIndex ) 159 { 160 return evaluator.getPattern().matcher( indexEntry.getValue() ).matches(); 161 } 162 else 163 { 164 return evaluator.evaluate( indexEntry ); 165 } 166 } 167 168 169 public boolean last() throws Exception 170 { 171 afterLast(); 172 return previous(); 173 } 174 175 176 public boolean previous() throws Exception 177 { 178 while ( wrapped.previous() ) 179 { 180 checkNotClosed( "previous()" ); 181 IndexEntry<String, ServerEntry, ID> entry = wrapped.get(); 182 if ( evaluateCandidate( entry ) ) 183 { 184 available = true; 185 this.indexEntry.setId( entry.getId() ); 186 this.indexEntry.setValue( entry.getValue() ); 187 this.indexEntry.setObject( entry.getObject() ); 188 return true; 189 } 190 } 191 192 clear(); 193 return false; 194 } 195 196 197 public boolean next() throws Exception 198 { 199 while ( wrapped.next() ) 200 { 201 checkNotClosed( "next()" ); 202 IndexEntry<String, ServerEntry, ID> entry = wrapped.get(); 203 if ( evaluateCandidate( entry ) ) 204 { 205 available = true; 206 this.indexEntry.setId( entry.getId() ); 207 this.indexEntry.setValue( entry.getValue() ); 208 this.indexEntry.setObject( entry.getObject() ); 209 return true; 210 } 211 } 212 213 clear(); 214 return false; 215 } 216 217 218 public IndexEntry<String, ServerEntry, ID> get() throws Exception 219 { 220 checkNotClosed( "get()" ); 221 if ( available ) 222 { 223 return indexEntry; 224 } 225 226 throw new InvalidCursorPositionException( I18n.err( I18n.ERR_708 ) ); 227 } 228 229 230 public boolean isElementReused() 231 { 232 return wrapped.isElementReused(); 233 } 234 235 236 public void close() throws Exception 237 { 238 super.close(); 239 wrapped.close(); 240 clear(); 241 } 242 }