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 * https://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.api.ldap.model.filter;
21
22 /**
23 * An empty class used for Undefined Nodes.
24 *
25 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
26 * @version $Rev$, $Date$
27 */
28 public final class UndefinedNode extends AbstractExprNode
29 {
30 /** A static instance of this node */
31 public static final UndefinedNode UNDEFINED_NODE = new UndefinedNode( "" );
32
33 /** attribute on which this leaf is based */
34 protected String attribute;
35
36
37 /**
38 * Creates a new instance of UndefinedNode.
39 */
40 public UndefinedNode( String attribute )
41 {
42 super( AssertionType.UNDEFINED );
43
44 this.attribute = attribute;
45 }
46
47
48 /**
49 * {@inheritDoc}
50 *
51 * This implementation always returns false.
52 */
53 @Override
54 public boolean isLeaf()
55 {
56 return false;
57 }
58
59
60 /**
61 * {@inheritDoc}
62 *
63 * This implementation always returns null.
64 */
65 @Override
66 public Object accept( FilterVisitor visitor )
67 {
68 return null;
69 }
70
71
72 /**
73 * Tells if this Node is Schema aware.
74 *
75 * @return true if the Node is SchemaAware
76 */
77 @Override
78 public boolean isSchemaAware()
79 {
80 return false;
81 }
82
83
84 public void setAttribute( String attribute )
85 {
86 this.attribute = attribute;
87 }
88
89
90 /**
91 * {@inheritDoc}
92 */
93 @Override
94 public String toString()
95 {
96 return "(Undefined:" + attribute + ")";
97 }
98 }