1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 *
19 */
20 package org.apache.directory.server.xdbm.search.impl;
21
22
23 import org.apache.directory.shared.ldap.filter.ScopeNode;
24 import org.apache.directory.shared.ldap.filter.SearchScope;
25 import org.apache.directory.server.xdbm.IndexEntry;
26 import org.apache.directory.server.xdbm.Store;
27 import org.apache.directory.server.xdbm.search.Evaluator;
28
29
30 /**
31 * Evaluates one level scope assertions on candidates using an entry database.
32 *
33 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
34 * @version $Rev: 659774 $
35 */
36 public class OneLevelScopeEvaluator<E> implements Evaluator<ScopeNode,E>
37 {
38 /** The ScopeNode containing initial search scope constraints */
39 private final ScopeNode node;
40
41 /** The entry identifier of the scope base */
42 private final Long baseId;
43
44 /** True if the scope requires alias dereferencing while searching */
45 private final boolean dereferencing;
46
47 /** the entry db storing entries */
48 private final Store<E> db;
49
50
51 /**
52 * Creates a one level scope node Evaluator for search expressions.
53 *
54 * @param node the scope node
55 * @param db the database used to evaluate scope node
56 * @throws Exception on db access failure
57 */
58 public OneLevelScopeEvaluator( Store<E> db, ScopeNode node ) throws Exception
59 {
60 this.node = node;
61
62 if ( node.getScope() != SearchScope.ONELEVEL )
63 {
64 throw new IllegalStateException( "ScopeNode is not of onelevel scope." );
65 }
66
67 this.db = db;
68 baseId = db.getEntryId( node.getBaseDn() );
69 dereferencing = node.getDerefAliases().isDerefInSearching() ||
70 node.getDerefAliases().isDerefAlways();
71 }
72
73
74 /**
75 * Asserts whether or not a candidate has one level scope while taking
76 * alias dereferencing into account.
77 *
78 * @param candidate the candidate to assert
79 * @return true if the candidate is within one level scope
80 * @throws Exception if db lookups fail
81 * @see org.apache.directory.server.xdbm.search.Evaluator#evaluate(IndexEntry)
82 */
83 public boolean evaluate( Long candidate ) throws Exception
84 {
85 boolean isChild = db.getOneLevelIndex().forward( baseId, candidate );
86
87 /*
88 * The candidate id could be any entry in the db. If search
89 * dereferencing is not enabled then we return the results of the child
90 * test.
91 */
92 if ( ! dereferencing )
93 {
94 return isChild;
95 }
96
97 /*
98 * From here down alias dereferencing is enabled. We determine if the
99 * 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 evaluate( E candidate ) throws Exception
140 {
141 throw new UnsupportedOperationException( "This is too inefficient without getId() on ServerEntry" );
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> 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 Long 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 }