1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.functor.core.collection;
18
19 import java.lang.reflect.Array;
20 import java.util.Collection;
21
22 import org.apache.commons.functor.Function;
23 import org.apache.commons.lang3.Validate;
24
25 /**
26 * Returns the size of the specified Collection, or the length
27 * of the specified array or String.
28 *
29 * @param <A> the function argument type.
30 * @version $Revision: 1537901 $ $Date: 2013-11-01 12:30:19 +0100 (Fr, 01 Nov 2013) $
31 */
32 public final class Size<A> implements Function<A, Integer> {
33
34 /**
35 * A static {@code Size} instance reference.
36 */
37 private static final Size<Object> INSTANCE = new Size<Object>();
38
39 // constructor
40 // ------------------------------------------------------------------------
41 /**
42 * Create a new Size.
43 */
44 public Size() { }
45
46 /**
47 * {@inheritDoc}
48 */
49 public Integer evaluate(Object obj) {
50 Validate.notNull(obj, "Argument must not be null");
51 if (obj instanceof Collection<?>) {
52 return evaluate((Collection<?>) obj);
53 }
54 if (obj instanceof String) {
55 return evaluate((String) obj);
56 }
57 if (obj.getClass().isArray()) {
58 return evaluateArray(obj);
59 }
60 throw new IllegalArgumentException("Expected Collection, String or Array, found " + obj);
61 }
62
63 /**
64 * {@inheritDoc}
65 */
66 @Override
67 public boolean equals(Object that) {
68 return that instanceof Size<?>;
69 }
70
71 /**
72 * {@inheritDoc}
73 */
74 @Override
75 public int hashCode() {
76 return "Size".hashCode();
77 }
78
79 /**
80 * {@inheritDoc}
81 */
82 @Override
83 public String toString() {
84 return "Size()";
85 }
86
87 /**
88 * Get a Size instance.
89 * @return Size
90 */
91 public static Size<Object> instance() {
92 return INSTANCE;
93 }
94
95 /**
96 * Evaluate a Collection.
97 * @param col to evaluate
98 * @return Integer
99 */
100 private Integer evaluate(Collection<?> col) {
101 return Integer.valueOf(col.size());
102 }
103
104 /**
105 * Evaluate a String.
106 * @param str to evaluate
107 * @return Integer
108 */
109 private Integer evaluate(String str) {
110 return Integer.valueOf(str.length());
111 }
112
113 /**
114 * Evaluate an array.
115 * @param array to evaluate
116 * @return Integer
117 */
118 private Integer evaluateArray(Object array) {
119 return Integer.valueOf(Array.getLength(array));
120 }
121
122 }