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.shared.ldap.filter.ScopeNode;
024 import org.apache.directory.shared.ldap.filter.SearchScope;
025 import org.apache.directory.server.i18n.I18n;
026 import org.apache.directory.server.xdbm.IndexEntry;
027 import org.apache.directory.server.xdbm.Store;
028 import org.apache.directory.server.xdbm.search.Evaluator;
029
030
031 /**
032 * Evaluates one level scope assertions on candidates using an entry database.
033 *
034 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
035 * @version $Rev: 917312 $
036 */
037 public class OneLevelScopeEvaluator<E, ID> implements Evaluator<ScopeNode, E, ID>
038 {
039 /** The ScopeNode containing initial search scope constraints */
040 private final ScopeNode node;
041
042 /** The entry identifier of the scope base */
043 private final ID baseId;
044
045 /** True if the scope requires alias dereferencing while searching */
046 private final boolean dereferencing;
047
048 /** the entry db storing entries */
049 private final Store<E, ID> db;
050
051
052 /**
053 * Creates a one level scope node Evaluator for search expressions.
054 *
055 * @param node the scope node
056 * @param db the database used to evaluate scope node
057 * @throws Exception on db access failure
058 */
059 public OneLevelScopeEvaluator( Store<E, ID> db, ScopeNode node ) throws Exception
060 {
061 this.node = node;
062
063 if ( node.getScope() != SearchScope.ONELEVEL )
064 {
065 throw new IllegalStateException( I18n.err( I18n.ERR_720 ) );
066 }
067
068 this.db = db;
069 baseId = db.getEntryId( node.getBaseDn() );
070 dereferencing = node.getDerefAliases().isDerefInSearching() || node.getDerefAliases().isDerefAlways();
071 }
072
073
074 /**
075 * Asserts whether or not a candidate has one level scope while taking
076 * alias dereferencing into account.
077 *
078 * @param candidate the candidate to assert
079 * @return true if the candidate is within one level scope
080 * @throws Exception if db lookups fail
081 * @see org.apache.directory.server.xdbm.search.Evaluator#evaluate(IndexEntry)
082 */
083 public boolean evaluateId( ID candidate ) throws Exception
084 {
085 boolean isChild = db.getOneLevelIndex().forward( baseId, candidate );
086
087 /*
088 * The candidate id could be any entry in the db. If search
089 * dereferencing is not enabled then we return the results of the child
090 * test.
091 */
092 if ( !dereferencing )
093 {
094 return isChild;
095 }
096
097 /*
098 * From here down alias dereferencing is enabled. We determine if the
099 * candidate id is an alias, if so we reject it since aliases should
100 * not be returned.
101 */
102 if ( null != db.getAliasIndex().reverseLookup( candidate ) )
103 {
104 return false;
105 }
106
107 /*
108 * The candidate is NOT an alias at this point. So if it is a child we
109 * just return true since it is in normal one level scope.
110 */
111 if ( isChild )
112 {
113 return true;
114 }
115
116 /*
117 * At this point the candidate is not a child and it is not an alias.
118 * We need to check if the candidate is in extended one level scope by
119 * performing a lookup on the one level alias index. This index stores
120 * a tuple mapping the baseId to the id of objects brought into the
121 * one level scope of the base by an alias: ( baseId, aliasedObjId )
122 * If the candidate id is an object brought into one level scope then
123 * the lookup returns true accepting the candidate. Otherwise the
124 * candidate is rejected with a false return because it is not in scope.
125 */
126 return db.getOneAliasIndex().forward( baseId, candidate );
127 }
128
129
130 /**
131 * Asserts whether or not a candidate has one level scope while taking
132 * alias dereferencing into account.
133 *
134 * TODO - terribly inefficient - would benefit from exposing the id of an
135 * entry within the ServerEntry
136 *
137 * @see Evaluator#evaluate(Object)
138 */
139 public boolean evaluateEntry( E candidate ) throws Exception
140 {
141 throw new UnsupportedOperationException( I18n.err( I18n.ERR_721 ) );
142 }
143
144
145 /**
146 * Asserts whether or not a candidate has one level scope while taking
147 * alias dereferencing into account.
148 *
149 * @param candidate the candidate to assert
150 * @return true if the candidate is within one level scope
151 * @throws Exception if db lookups fail
152 * @see org.apache.directory.server.xdbm.search.Evaluator#evaluate(IndexEntry)
153 */
154 public boolean evaluate( IndexEntry<?, E, ID> candidate ) throws Exception
155 {
156 boolean isChild = db.getOneLevelIndex().forward( baseId, candidate.getId() );
157
158 /*
159 * The candidate id could be any entry in the db. If search
160 * dereferencing is not enabled then we return the results of the child
161 * test.
162 */
163 if ( !dereferencing )
164 {
165 return isChild;
166 }
167
168 /*
169 * From here down alias dereferencing is enabled. We determine if the
170 * candidate id is an alias, if so we reject it since aliases should
171 * not be returned.
172 */
173 if ( null != db.getAliasIndex().reverseLookup( candidate.getId() ) )
174 {
175 return false;
176 }
177
178 /*
179 * The candidate is NOT an alias at this point. So if it is a child we
180 * just return true since it is in normal one level scope.
181 */
182 if ( isChild )
183 {
184 return true;
185 }
186
187 /*
188 * At this point the candidate is not a child and it is not an alias.
189 * We need to check if the candidate is in extended one level scope by
190 * performing a lookup on the one level alias index. This index stores
191 * a tuple mapping the baseId to the id of objects brought into the
192 * one level scope of the base by an alias: ( baseId, aliasedObjId )
193 * If the candidate id is an object brought into one level scope then
194 * the lookup returns true accepting the candidate. Otherwise the
195 * candidate is rejected with a false return because it is not in scope.
196 */
197 return db.getOneAliasIndex().forward( baseId, candidate.getId() );
198 }
199
200
201 public ScopeNode getExpression()
202 {
203 return node;
204 }
205
206
207 /**
208 * Gets the id of the search base associated with the ScopeNode expression.
209 *
210 * @return identifier of the search base
211 */
212 public ID getBaseId()
213 {
214 return baseId;
215 }
216
217
218 /**
219 * Gets whether or not dereferencing is enabled for this evaluator.
220 *
221 * @return true if dereferencing is enabled, false otherwise
222 */
223 public boolean isDereferencing()
224 {
225 return dereferencing;
226 }
227 }