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.core.api.partition.PartitionTxn;
27 import org.apache.directory.server.xdbm.IndexEntry;
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 /**
39 * Create a new instance of the PassThroughEvaluator
40 */
41 public EmptyEvaluator()
42 {
43 }
44
45
46 /**
47 * {@inheritDoc}
48 */
49 public boolean evaluate( PartitionTxn partitionTxn, IndexEntry<?, String> indexEntry ) throws LdapException
50 {
51 return false;
52 }
53
54
55 /**
56 * {@inheritDoc}
57 */
58 public boolean evaluate( Entry entry ) throws LdapException
59 {
60 return false;
61 }
62
63
64 /**
65 * Gets the expression used by this expression Evaluator.
66 *
67 * @return the AST for the expression
68 */
69 public UndefinedNode getExpression()
70 {
71 return UndefinedNode.UNDEFINED_NODE;
72 }
73
74
75 /**
76 * @see Object#toString()
77 */
78 public String toString( String tabs )
79 {
80 StringBuilder sb = new StringBuilder();
81
82 sb.append( tabs ).append( "EmptyEvaluator\n" );
83
84 return sb.toString();
85 }
86
87
88 /**
89 * @see Object#toString()
90 */
91 public String toString()
92 {
93 return toString( "" );
94 }
95 }