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.evaluator;
21
22
23 import org.apache.directory.api.ldap.model.entry.Entry;
24 import org.apache.directory.api.ldap.model.exception.LdapException;
25 import org.apache.directory.api.ldap.model.filter.UndefinedNode;
26 import org.apache.directory.server.xdbm.IndexEntry;
27 import org.apache.directory.server.xdbm.Store;
28 import org.apache.directory.server.xdbm.search.Evaluator;
29
30
31 /**
32 * An Evaluator that always return false, for the case we have no entry to return
33 *
34 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
35 */
36 public class EmptyEvaluator implements Evaluator<UndefinedNode>
37 {
38 /** The backend */
39 private final Store db;
40
41
42 /**
43 * Create a new instance of the PassThroughEvaluator
44 * @throws Exception
45 */
46 public EmptyEvaluator( Store db )
47 {
48 this.db = db;
49 }
50
51
52 /**
53 * {@inheritDoc}
54 */
55 public boolean evaluate( IndexEntry<?, String> indexEntry ) throws LdapException
56 {
57 return false;
58 }
59
60
61 /**
62 * {@inheritDoc}
63 */
64 public boolean evaluate( Entry entry ) throws Exception
65 {
66 return false;
67 }
68
69
70 /**
71 * Gets the expression used by this expression Evaluator.
72 *
73 * @return the AST for the expression
74 */
75 public UndefinedNode getExpression()
76 {
77 return null;
78 }
79
80
81 /**
82 * @see Object#toString()
83 */
84 public String toString( String tabs )
85 {
86 StringBuilder sb = new StringBuilder();
87
88 sb.append( tabs ).append( "EmptyEvaluator\n" );
89
90 return sb.toString();
91 }
92
93
94 /**
95 * @see Object#toString()
96 */
97 public String toString()
98 {
99 return toString( "" );
100 }
101 }