1 /***
2 * Copyright 2003-2010 Terracotta, Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package net.sf.ehcache.search;
18
19 import java.util.Collections;
20 import java.util.List;
21
22 /***
23 * An empty result instance
24 *
25 * @author teck
26 */
27 public class NullResults implements Results {
28
29 /***
30 * A global instance that can be freely shared with the world since this type has no state
31 */
32 public static final NullResults INSTANCE = new NullResults();
33
34 /***
35 * {@inheritDoc}
36 */
37 public void discard() {
38
39 }
40
41 /***
42 * {@inheritDoc}
43 */
44 public List<Result> all() throws SearchException {
45 return Collections.EMPTY_LIST;
46 }
47
48 /***
49 * {@inheritDoc}
50 */
51 public List<Result> range(int start, int count) throws SearchException, IndexOutOfBoundsException {
52 return Collections.EMPTY_LIST;
53 }
54
55 /***
56 * {@inheritDoc}
57 */
58 public int size() {
59 return 0;
60 }
61
62 /***
63 * {@inheritDoc}
64 */
65 public boolean hasKeys() {
66 return false;
67 }
68
69 /***
70 * {@inheritDoc}
71 */
72 public boolean hasValues() {
73 return false;
74 }
75
76 /***
77 * {@inheritDoc}
78 */
79 public boolean hasAttributes() {
80 return false;
81 }
82
83 /***
84 * {@inheritDoc}
85 */
86 public boolean hasAggregators() {
87 return false;
88 }
89
90 }